Languages: English (fluent), Spanish (fluent)
- Clinical Trials
- Molecular/PET Imaging
- Tumor Treating Fields (TTFields)
Honors & Awards
Dee S. and Patricia Osborne Endowed Scholarship in the Neurosciences, University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences
Diversity Recognition Award, Johns Hopkins University Diversity Leadership Council
Future Clinical Researchers in Neurology and Neuroscience Scholarship, American Academy of Neurology
Honors Scholar in Medical Education, Stanford University School of Medicine Teaching and Mentoring Academy
Martin Luther King, Jr. Award for Community Service, Johns Hopkins University
Neurologist-In-Training Clinical Ethics Elective, American Academy of Neurology
Palatucci Advocacy Leadership Forum, American Academy of Neurology
Student Travel Stipend Award, World Molecular Imaging Congress
Young Investigator Palatucci Research Award, California Neurology Society
Boards, Advisory Committees, Professional Organizations
Associate Member Council (AMC) Member, American Association for Cancer Research (2018 - Present)
Member, American Association for Cancer Research (2016 - Present)
Member, Society for Neuro-Oncology (2014 - Present)
Member, American Physician Scientists Association (2005 - Present)
Member, American Academy of Neurology (2005 - Present)
Member, Sigma Xi (2005 - Present)
Clinical Fellowship, Stanford University School of Medicine Department of Neurology, Neuro-oncology
Postdoctoral Fellowship, Stanford University School of Medicine Department of Radiology, Multimodal Molecular Imaging
Residency, University of California at Los Angeles David Geffen School of Medicine Department of Neurology, Adult Neurology
Internship, East Tennessee State University James H. Quillen College of Medicine Department of Internal Medicine, Internal Medicine
MD, University of Texas at Houston John P. and Kathrine G. McGovern Medical School
PhD, University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences
MSE, Johns Hopkins University, Biomedical Engineering
BS, Johns Hopkins University, Biomedical Engineering
Sanjiv Gambhir, Postdoctoral Faculty Sponsor
Community and International Work
Arbor Free Clinic Specialty Service (Neurology), Menlo Park VA Hospital
VA Palo Alto Health Care System, Menlo Park Division
Opportunities for Student Involvement
Clinical Neurology Clerkship Bedside Teaching, Stanford Hospital
Stanford University School of Medicine Department of Neurology and Neurological Sciences
Opportunities for Student Involvement
Stanford Science Penpals
Stanford Office of Science Outreach
High school students
Opportunities for Student Involvement
Graduate and Fellowship Programs
Oncology (Fellowship Program)
Evaluation of Glycolytic Response to Multiple Classes of Anti-glioblastoma Drugs by Noninvasive Measurement of Pyruvate Kinase M2 Using [18F]DASA-23.
Molecular imaging and biology : MIB : the official publication of the Academy of Molecular Imaging
PURPOSE: Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, the key process of tumor metabolism. PKM2 is found in high levels in glioblastoma (GBM) cells with marginal expression within healthy brain tissue, rendering it a key biomarker of GBM metabolic re-programming. Our group has reported the development of a novel radiotracer, 1-((2-fluoro- 6-[18F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA- 23), to non-invasively detect PKM2 levels with positron emission tomography (PET).PROCEDURE: U87 human GBM cells were treated with the IC50 concentration of various agents used in the treatment of GBM, including alkylating agents (temozolomide, carmustine, lomustine, procarbazine), inhibitor of topoisomerase I (irinotecan), vascular endothelial and epidermal growth factor receptor inhibitors (cediranib and erlotinib, respectively) anti-metabolite (5-fluorouracil), microtubule inhibitor (vincristine), and metabolic agents (dichloroacetate and IDH1 inhibitor ivosidenib). Following drug exposure for three or 6days (n=6 replicates per condition), the radiotracer uptake of [18F]DASA-23 and 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) was assessed. Changes in PKM2 protein levels were determined via Western blot and correlated to radiotracer uptake.RESULTS: Significant interactions were found between the treatment agent (n=12 conditions total comprised 11 drugs and vehicle) and the duration of treatment (3- or 6-day exposure to each drug) on the cellular uptake of [18F]DASA-23 (p=0.0001). The greatest change in the cellular uptake of [18F]DASA-23 was found after exposure to alkylating agents (p<0. 0001) followed by irinotecan (p=0. 0012), erlotinib (p=0. 02), and 5-fluorouracil (p=0. 005). Correlation of PKM2 protein levels and [18F]DASA-23 cellular uptake revealed a moderate correlation (r=0.44, p=0.15).CONCLUSIONS: These proof of principle studies emphasize the superiority of [18F]DASA-23 to [18F]FDG in detecting the glycolytic response of GBM to multiple classes of anti-neoplastic drugs in cell culture. A clinical trial evaluating the diagnostic utility of [18F]DASA-23 PET in GBM patients (NCT03539731) is ongoing.
View details for PubMedID 30989436
Nanomedicine for Spontaneous Brain Tumors: A Companion Clinical Trial.
Nanoparticles' enhanced permeation and retention (EPR) variations due to tumor heterogeneity in naturally occurring brain tumors are commonly neglected in preclinical nanomedicine studies. Recent pathological studies have shown striking similarities between brain tumors in humans and dogs, indicating that canine brain tumors may be a valuable model to evaluate nanoparticles' EPR in this context. We recruited canine clinical cases with spontaneous brain tumors to investigate nanoparticles' EPR in different brain tumor pathologies using surface-enhanced Raman spectroscopy (SERS). We used gold nanoparticles due to their surface plasmon effect that enables their sensitive and microscopic resolution detection using the SERS technique. Raman microscopy of the resected tumors showed heterogeneous EPR of nanoparticles into oligodendrogliomas and meningiomas of different grades, without any detectable traces in necrotic parts of the tumors or normal brain. Raman observations were confirmed by scanning electron microscopy (SEM) and X-ray elemental analyses, which enabled localization of individual nanoparticles embedded in tumor tissues. Our results demonstrate nanoparticles' EPR and its variations in clinically relevant, spontaneous brain tumors. Such heterogeneities should be considered alongside routine preoperative imaging and histopathological analyses in order to accelerate clinical management of brain tumors using nanomedicine approaches.
View details for PubMedID 30714717
Positron emission tomography reporter gene strategy for use in the central nervous system
View details for DOI 10.1073/pnas.1901645116
Engineered immune cells as highly sensitive cancer diagnostics.
Endogenous biomarkers remain at the forefront of early disease detection efforts, but many lack the sensitivities and specificities necessary to influence disease management. Here, we describe a cell-based in vivo sensor for highly sensitive early cancer detection. We engineer macrophages to produce a synthetic reporter on adopting an M2 tumor-associated metabolic profile by coupling luciferase expression to activation of the arginase-1 promoter. After adoptive transfer in colorectal and breast mouse tumor models, the engineered macrophages migrated to the tumors and activated arginase-1 so that they could be detected by bioluminescence imaging and luciferase measured in the blood. The macrophage sensor detected tumors as small as 25-50 mm3 by blood luciferase measurements, even in the presence of concomitant inflammation, and was more sensitive than clinically used protein and nucleic acid cancer biomarkers. Macrophage sensors also effectively tracked the immunological response in muscle and lung models of inflammation, suggesting the potential utility of this approach in disease states other than cancer.
View details for PubMedID 30886438
A novel metabolic PET tracer strategy to determine early effects of Tumor Treating Fields (TTFields)
Society for Neuro-Oncology (SNO) 23rd Annual Meeting
View details for DOI 10.1093/neuonc/noy148.122
- Molecular imaging of pyruvate kinase M2 (PKM2) with [18F]DASA-23 detects temozolomide- and tumor treating fields (TTFields)-induced changes in glycolysis in preclinical models of glioblastoma World Molecular Imaging Congress
Dosimetry Prediction for Clinical Translation of 64Cu-Pembrolizumab ImmunoPET Targeting Human PD-1 Expression.
2018; 8 (1): 633
The immune checkpoint programmed death 1 receptor (PD-1) expressed on some tumor-infiltrating lymphocytes, and its ligand (PD-L1) expressed on tumor cells, enable cancers to evade the immune system. Blocking PD-1 with the monoclonal antibody pembrolizumab is a promising immunotherapy strategy. Thus, noninvasively quantifying the presence of PD-1 expression in the tumor microenvironment prior to initiation of immune checkpoint blockade may identify the patients likely to respond to therapy. We have developed a 64Cu-pembrolizumab radiotracer and evaluated human dosimetry. The tracer was utilized to image hPD-1 levels in two subcutaneous mouse models: (a) 293 T/hPD-1 cells xenografted into NOD-scid IL-2Rγnull mice (NSG/293 T/hPD-1) and (b) human peripheral blood mononuclear cells engrafted into NSG bearing A375 human melanoma tumors (hNSG/A375). In each mouse model two cohorts were evaluated (hPD-1 blockade with pembrolizumab [blk] and non-blocked [nblk]), for a total of four groups (n = 3-5/group). The xenograft-to-muscle ratio in the NSG/293 T/hPD-1 model at 24 h was significantly increased in the nblk group (7.0 ± 0.5) compared to the blk group (3.4 ± 0.9), p = 0.01. The radiotracer dosimetry evaluation (PET/CT ROI-based and ex vivo) in the hNSG/A375 model revealed the highest radiation burden to the liver. In summary, we validated the 64Cu-pembrolizumab tracer's specific hPD-1 receptor targeting and predicted human dosimetry.
View details for PubMedID 29330552
18F-FDOPA PET and MRI characteristics correlate with degree of malignancy and predict survival in treatment-naïve gliomas: a cross-sectional study.
Journal of neuro-oncology
To report the potential value of pre-operative 18F-FDOPA PET and anatomic MRI in diagnosis and prognosis of glioma patients.Forty-five patients with a pathological diagnosis of glioma with pre-operative 18F-FDOPA PET and anatomic MRI were retrospectively examined. The volume of contrast enhancement and T2 hyperintensity on MRI images along with the ratio of maximum 18F-FDOPA SUV in tumor to normal tissue (T/N SUVmax) were measured and used to predict tumor grade, molecular status, and overall survival (OS).A significant correlation was observed between WHO grade and: the volume of contrast enhancement (r = 0.67), volume of T2 hyperintensity (r = 0.42), and 18F-FDOPA uptake (r = 0.60) (P < 0.01 for each correlation). The volume of contrast enhancement and 18F-FDOPA T/N SUVmax were significantly higher in glioblastoma (WHO IV) compared with lower grade gliomas (WHO I-III), as well as for high-grade gliomas (WHO III-IV) compared with low-grade gliomas (WHO I-II). Receiver-operator characteristic (ROC) analyses confirmed the volume of contrast enhancement and 18F-FDOPA T/N SUVmax could each differentiate patient groups. No significant differences in 18F-FDOPA uptake were observed by IDH or MGMT status. Multivariable Cox regression suggested age (HR 1.16, P = 0.0001) and continuous measures of 18F-FDOPA PET T/N SUVmax (HR 4.43, P = 0.016) were significant prognostic factors for OS in WHO I-IV gliomas.Current findings suggest a potential role for the use of pre-operative 18F-FDOPA PET in suspected glioma. Increased 18F-FDOPA uptake may not only predict higher glioma grade, but also worse OS.
View details for DOI 10.1007/s11060-018-2877-6
View details for PubMedID 29679199
A Novel Engineered Small Protein for Positron Emission Tomography Imaging of Human Programmed Death Ligand-1 : Validation in Mouse Models and Human Cancer Tissues
Clinical Cancer Res
View details for DOI 10.1158/1078-0432.CCR-18-1871
Tumor Treating Fields Increases Membrane Permeability in Glioblastoma Cells
Cell Death Discovery
View details for DOI 10.1038/s41420-018-0130-x
Conditional Probability of Survival as a Proposed Endpoint for Future Single-Arm Clinical Trials in Glioblastoma
142nd Annual Meeting of the American Neurological Association
View details for DOI 10.1002/ana.25024
Evaluation of glycolytic response to seven classes of anti-glioblastoma drugs by non-invasive measurement of pyruvate kinase M2
Society for Neuro-Oncology (SNO) 23rd Annual Meeting
View details for DOI 10.1093/neuonc/noy148.126
- Brain Tumor Imaging Using Surface-Enhanced Raman Spectroscopy (SERS): A Companion Clinical Trial World Molecular Imaging Congress
Comparison of three metabolic PET radiotracers in glioblastoma: cell culture and animal studies
Society for Neuro-Oncology (SNO) 23rd Annual Meeting
View details for DOI 10.1093/neuonc/noy148.127
Surface-enhanced Raman Spectroscopy (SERS) for Intraoperative Brain Tumor Imaging and Photothermal Therapy
22nd Annual Scientific Meeting and Education Day of the Society for Neuro-Oncology
View details for DOI 10.1093/neuonc/nox168.648
The Utility of [18F]DASA-23 for Molecular Imaging of Prostate Cancer with Positron Emission Tomography.
Molecular imaging and biology : MIB : the official publication of the Academy of Molecular Imaging
There is a strong, unmet need for superior positron emission tomography (PET) imaging agents that are able to measure biochemical processes specific to prostate cancer. Pyruvate kinase M2 (PKM2) catalyzes the concluding step in glycolysis and is a key regulator of tumor growth and metabolism. Elevation of PKM2 expression was detected in Gleason 8-10 tumors compared to Gleason 6-7 carcinomas, indicating that PKM2 may potentially be a marker of aggressive prostate cancer. We have recently reported the development of a PKM2-specific radiopharmaceutical [18F]DASA-23 and herein describe its evaluation in cell culture and preclinical models of prostate cancer.The cellular uptake of [18F]DASA-23 was evaluated in a panel of prostate cancer cell lines and compared to that of [18F]FDG. The specificity of [18F]DASA-23 to measure PKM2 levels in cell culture was additionally confirmed through the use of PKM2-specific siRNA. PET imaging studies were then completed utilizing subcutaneous prostate cancer xenografts using either PC3 or DU145 cells in mice.[18F]DASA-23 uptake values over 60-min incubation period in PC3, LnCAP, and DU145 respectively were 23.4 ± 4.5, 18.0 ± 2.1, and 53.1 ± 4.6 % tracer/mg protein. Transient reduction in PKM2 protein expression with siRNA resulted in a 50.1 % reduction in radiotracer uptake in DU145 cells. Small animal PET imaging revealed 0.86 ± 0.13 and 1.6 ± 0.2 % ID/g at 30 min post injection of radioactivity in DU145 and PC3 subcutaneous tumor bearing mice respectively.Herein, we evaluated a F-18-labeled PKM2-specific radiotracer, [18F]DASA-23, for the molecular imaging of prostate cancer with PET. [18F]DASA-23 revealed rapid and extensive uptake levels in cellular uptake studies of prostate cancer cells; however, there was only modest tumor uptake when evaluated in mouse subcutaneous tumor models.
View details for PubMedID 29736561
- From Subsistence to Sustenance in Physician-Scientist Training. Academic medicine : journal of the Association of American Medical Colleges 2018
- Needs Assessment of Neuro-Oncology Education in the Stanford School of Medicine’s Undergraduate Medical and Neurology Residency Curricula Second Stanford Innovations in Medical Education Conference
Angiopoietin-1 Reduces Blood-Spinal Cord Barrier Permeability and Lesion Volume in the Acute Phase of Spinal Cord Injury: MRI and Histological Studies
Second Joint Symposium of The International & National Neurotrauma Societies
View details for DOI 10.1089/neu.2009.9953
3D Probability Distribution of Treatment Targets: A New Way to Define 3D Organ Motion for Prostate Cancer Radiotherapy
American Society for Radiation Oncology
View details for DOI 10.1016/j.ijrobp.2005.07.884
- Developing a Novel Therapeutic Game for Children with Autism Spectrum Disorder First AMA-IEEE Conference on Medical Technology
Residual entropy reveals effects of deep brain stimulation on neural activity in PTZ-induced epilepsy
25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society
View details for DOI 10.1109/IEMBS.2003.1280370
Impact of preoperative radiation dose escalation on pathologic outcomes and radiation toxicity in locally advanced rectal cancer (LARC): A matched-pair analysis
American Society of Clinical Oncology
View details for DOI 10.1200/jco.2011.29.15_suppl.e14036
Unbiased frequency estimation of narrowband signals using Procrustes type subspace rotation
IEEE International Conference on Acoustics, Speech, and Signal Processing
View details for DOI 10.1109/ICASSP.2002.5744946
- The Impact of a Brief Intervention on Medical Students' Readiness to Screen for DV - Changes in Decisional Balance and Self-Efficacy UTHealth Advances in Teaching and Learning Day
- MRI Ventral Nerve Root Enhancement In 3 Patients Presenting With Lower Extremity Weakness Secondary To West Nile Virus American Academy of Neurology : P2.311
- A Student-Initiated Elective in Medical Ethics: Innovations in Design and Institutionalization UTHealth Advances in Teaching and Learning Day
Neurological Manifestations of West Nile Virus at Olive View Ucla Medical Center 2012-2013
American Neurological Association
View details for DOI 10.1002/ana.24247
Synergistic inhibition of glioma cell proliferation by Withaferin A and tumor treating fields.
Journal of neuro-oncology
Glioblastoma (GBM) is the most aggressive and lethal form of brain cancer. Standard therapies are non-specific and often of limited effectiveness; thus, efforts are underway to uncover novel, unorthodox therapies against GBM. In previous studies, we investigated Withaferin A, a steroidal lactone from Ayurvedic medicine that inhibits proliferation in cancers including GBM. Another novel approach, tumor treating fields (TTFields), is thought to disrupt mitotic spindle formation and stymie proliferation of actively dividing cells. We hypothesized that combining TTFields with Withaferin A would synergistically inhibit proliferation in glioblastoma. Human glioblastoma cells (GBM2, GBM39, U87-MG) and human breast adenocarcinoma cells (MDA-MB-231) were isolated from primary tumors. The glioma cell lines were genetically engineered to express firefly luciferase. Proliferative potential was assessed either by bioluminescence imaging or cell counting via hemocytometer. TTFields (4 V/cm) significantly inhibited growth of the four cancer cell lines tested (n = 3 experiments per time point, four measurements per sample, p < 0.02 at least; 2-way ANOVA, control vs. treatment). The combination of Withaferin A (10-100 nM) with TTFields significantly inhibited the growth of the glioma cells to a degree beyond that of Withaferin A or TTFields alone. The interaction of the Withaferin A and TTFields on glioma cells was found to be synergistic in nature (p < 0.01, n = 3 experiments). These findings were validated by both bioluminescence and hemocytometric measurements. The combination of Withaferin A with TTFields represents a novel approach to treat GBM in a manner that is likely better than either treatment alone and that is synergistic.
View details for PubMedID 28681243
Southern California neuroinvasive West Nile virus case series.
View details for DOI 10.1007/s10072-017-3164-6
- Movements Here Today, Gone Tomorrow: Images in Clinical Neurology Case of Hyperglycemic Hemichorea. The Neurohospitalist 2017; 7 (3): 150
- A single demyelinating attack is enough to limit brain growth in children. Neurology 2017
Natural Language Processing-Enabled and Conventional Data Capture Methods for Input to Electronic Health Records: A Comparative Usability Study.
JMIR medical informatics
2016; 4 (4)
The process of documentation in electronic health records (EHRs) is known to be time consuming, inefficient, and cumbersome. The use of dictation coupled with manual transcription has become an increasingly common practice. In recent years, natural language processing (NLP)-enabled data capture has become a viable alternative for data entry. It enables the clinician to maintain control of the process and potentially reduce the documentation burden. The question remains how this NLP-enabled workflow will impact EHR usability and whether it can meet the structured data and other EHR requirements while enhancing the user's experience.The objective of this study is evaluate the comparative effectiveness of an NLP-enabled data capture method using dictation and data extraction from transcribed documents (NLP Entry) in terms of documentation time, documentation quality, and usability versus standard EHR keyboard-and-mouse data entry.This formative study investigated the results of using 4 combinations of NLP Entry and Standard Entry methods ("protocols") of EHR data capture. We compared a novel dictation-based protocol using MediSapien NLP (NLP-NLP) for structured data capture against a standard structured data capture protocol (Standard-Standard) as well as 2 novel hybrid protocols (NLP-Standard and Standard-NLP). The 31 participants included neurologists, cardiologists, and nephrologists. Participants generated 4 consultation or admission notes using 4 documentation protocols. We recorded the time on task, documentation quality (using the Physician Documentation Quality Instrument, PDQI-9), and usability of the documentation processes.A total of 118 notes were documented across the 3 subject areas. The NLP-NLP protocol required a median of 5.2 minutes per cardiology note, 7.3 minutes per nephrology note, and 8.5 minutes per neurology note compared with 16.9, 20.7, and 21.2 minutes, respectively, using the Standard-Standard protocol and 13.8, 21.3, and 18.7 minutes using the Standard-NLP protocol (1 of 2 hybrid methods). Using 8 out of 9 characteristics measured by the PDQI-9 instrument, the NLP-NLP protocol received a median quality score sum of 24.5; the Standard-Standard protocol received a median sum of 29; and the Standard-NLP protocol received a median sum of 29.5. The mean total score of the usability measure was 36.7 when the participants used the NLP-NLP protocol compared with 30.3 when they used the Standard-Standard protocol.In this study, the feasibility of an approach to EHR data capture involving the application of NLP to transcribed dictation was demonstrated. This novel dictation-based approach has the potential to reduce the time required for documentation and improve usability while maintaining documentation quality. Future research will evaluate the NLP-based EHR data capture approach in a clinical setting. It is reasonable to assert that EHRs will increasingly use NLP-enabled data entry tools such as MediSapien NLP because they hold promise for enhancing the documentation process and end-user experience.
View details for PubMedID 27793791
- MRI Ventral Nerve Root Enhancement in Five Patients Presenting With Extremity Weakness Secondary to Neuroinvasive West Nile Virus. Journal of clinical neuromuscular disease 2016; 18 (1): 41-43
Multiple calcifying pseudoneoplasms of the neuraxis (MCAPNON): Distinct entity, CAPNON variant, or old neurocysticercosis?
Neuropathology : official journal of the Japanese Society of Neuropathology
We report a case of multiple calcifying pseudoneoplasms of the neuraxis (MCAPNON) with associated multifocal perivascular microcalcifications and vascular calcinosis. Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a very rare condition that may arise in extra-axial and occasionally, in intra-axial locations. Moreover, it is nearly always a solitary mass with only one case with two lesions reported. While the etiology and pathogenesis of CAPNON remains unclear, the histopathology findings of this entity have been well described. We report a case of a 62-year-old woman with 18 calcifying radiologic lesions involving bilateral cerebral hemispheres. Histologically, these lesions have features similar to that reported for CAPNON, including nodular calcification with fibro-osseous components and peripheral histiocytic reaction. The patient had a poorly documented diagnosis of neurocyticercosis 32 years prior, although without tissue confirmation. The lack of detectable cysticercus serum antibody titers, and absence of residual larval or cyst wall tissue render multifocal calcific involution of that parasite unprovable although still plausible. We also raise the possibility of a blood-brain barrier derangement and/or a metabolic disorder as an alternative etiology. Whether this case of MCAPNON shares the same pathogenesis as the usual solitary CAPNON is unclear.
View details for DOI 10.1111/neup.12349
View details for PubMedID 27862397
- The effects of anesthesia on the morphoproteomic expression of head and neck squamous cell carcinoma: a pilot study TRANSLATIONAL RESEARCH 2015; 166 (6): 674-682
Challenges and opportunities for reinvigorating the physician-scientist pipeline
JOURNAL OF CLINICAL INVESTIGATION
2015; 125 (3): 883-887
Physician-scientists, with in-depth training in both medicine and research, are uniquely poised to address pressing challenges at the forefront of biomedicine. In recent years, a number of organizations have outlined obstacles to maintaining the pipeline of physician-scientists, classifying them as an endangered species. As in-training and early-career physician-scientists across the spectrum of the pipeline, we share here our perspective on the current challenges and available opportunities that might aid our generation in becoming independent physician-scientists. These challenges revolve around the difficulties in recruitment and retention of trainees, the length of training and lack of support at key training transition points, and the rapidly and independently changing worlds of medical and scientific training. In an era of health care reform and an environment of increasingly sparse NIH funding, these challenges are likely to become more pronounced and complex. As stakeholders, we need to coalesce behind core strategic points and regularly assess the impact and progress of our efforts with appropriate metrics. Here, we expand on the challenges that we foresee and offer potential opportunities to ensure a more sustainable physician-scientist workforce.
View details for DOI 10.1172/JCI80933
View details for Web of Science ID 000350616500001
View details for PubMedID 25689260
Critical appraisal of learning curve for single incision laparoscopic right colectomy
SURGICAL ENDOSCOPY AND OTHER INTERVENTIONAL TECHNIQUES
2013; 27 (12): 4499-4503
Single-incision laparoscopic colectomy (SILC) has emerged as a viable minimally invasive surgical approach with benefits and limitations yet to be fully elucidated. Although shown to be safe and feasible, characterization of the learning curve has not been addressed. Our aim was to identify a learning curve for SILC right hemicolectomy and to determine the incidence of operative failure and complication rates during this phase.Over a 2-year period, data from 54 consecutive SILC cases performed by the same surgeon were tabulated in an institutional review board-approved database. A learning curve was generated utilizing cumulative sum (CUSUM) methodology to assess changes in total operative time (OT) across the case sequence. A separate learning curve was generated utilizing risk-adjusted CUSUM analysis, taking into account patient risk factors (i.e., age, American Society of Anesthesiologists score, body mass index, prior abdominal surgeries, and tumor size for malignant cases) and operative failure (i.e., prolonged OT, conversion to open surgery, intraoperative and 30-day postoperative complications, prolonged length of stay, reoperation, readmission, and mortality).Patients had a mean age of 63.6 ± 11.5 years, mean body mass index of 27.3 ± 3.9 kg/m(2), and median American Society of Anesthesiologists score of 2. Mean OT and length of stay were 123.5 ± 28.9 min and 3.9 ± 2.4 days, respectively. There were no conversions or oncologic failures. Six patients developed 30-day postoperative complications. CUSUM analysis of OT identified achievement of the learning phase after 30 cases. When taking into account both analyses, the rate of operative failure was not statistically different between the initial 30 and the final 24 cases.In our experience, the learning curve is achieved between 30 to 36 cases. Offering this minimally invasive surgical approach does not result in increased complications or harmful results even in the early phases of the learning curve.
View details for DOI 10.1007/s00464-013-3096-z
View details for Web of Science ID 000327144800012
View details for PubMedID 23877765
Optical rhinometry in nonallergic irritant rhinitis: a capsaicin challenge study
INTERNATIONAL FORUM OF ALLERGY & RHINOLOGY
2013; 3 (10): 795-800
Patients with nonallergic irritant rhinitis (NAIR) have symptoms of nasal congestion, nasal irritation, rhinorrhea, and sneezing in response to nasal irritants. We currently have no reliable objective means to quantify these patients' subjective symptoms. In this study, we used the transient receptor potential vanilloid receptor (TRPV1) receptor agonist, capsaicin, as an intranasal challenge while comparing the changes in blood flow with optical rhinometry between subjects with NAIR and healthy controls (HCs).Six HCs and 6 NAIR subjects were challenged intranasally with saline solution followed by increasing concentrations of capsaicin (0.005 mM, 0.05 mM, and 0.5 mM) at 15-minute intervals. We recorded maximum optical density (OD) and numeric analog scores (NAS) for nasal congestion, nasal irritation, rhinorrhea, and sneezing for each subject after each challenge. Correlations between NAS and maximum OD were calculated.Maximum OD increased with increasing concentrations of intranasal capsaicin in NAIR subjects. There were significant differences in maximum OD obtained for 0.05 mM and 0.5 mM capsaicin between NAIR subjects and HCs. Significant differences were found in the NAS for nasal irritation at 0.005 mM, 0.05 mM, and 0.5 mM, and nasal congestion at 0.5 mM. Correlation between maximum OD and mean NAS was most significant for 0.05 mM capsaicin.Optical rhinometry with intranasal capsaicin challenge could prove a viable option in the diagnosis of NAIR. Further studies will investigate its use to monitor a patient's response to pharmacologic therapy and provide further information about the underlying mechanisms of NAIR.
View details for DOI 10.1002/alr.21184
View details for Web of Science ID 000328223500004
View details for PubMedID 23733747
- Predictive Analytics: The Fifth Clinical Element SOUTHERN MEDICAL JOURNAL 2013; 106 (4): 290-291
Diffuse large B-cell lymphoma: A metabolic disorder?
The American journal of case reports
2013; 14: 518-525
Patient Male, 81 FINAL DIAGNOSIS: Non-Hodgkin lymphoma Symptoms: General weakness • hypoglycemia • metabolic acidosis- Clinical Procedure: - Specialty: Hematology.Challenging differential diagnosis.B cell lymphoma constitutes 80-85% of cases of Non Hodgkin's lymphoma in the Untied States. Metabolic complications may arise from the disease itself or through its end organ involvement.We describe a case of a diffuse large B cell lymphoma diagnosed by abdominal computed tomography after it initially presented as hypoglycemia not correctable by dextrose infusion that instead resulted in increased anion gap metabolic acidosis with elevated lactate levels.The case illustrates how lymphomas can present unusually with hypoglycemia and lactic acidosis, the latter being an ominous sign that can occur without liver involvement. In this regard, the case demonstrates the metabolic sequelae of lymphoma that should raise suspicion for an underlying process. This has implications for diagnosis, treatment, and patient survival. Attention should be paid especially in the primary care setting in order to minimize delays in diagnosis.
View details for PubMedID 24349605
Efficacy of 3% saline vs. conivaptan in achieving hyponatremia treatment goals.
Methodist DeBakey cardiovascular journal
2013; 9 (1): 49-53
Hyponatremia is the most common electrolyte abnormality encountered in clinical practice, but its optimal management is still evolving. While guidelines for infusion rates of hypertonic saline (HS) have been introduced, there is a risk of underestimating the response in serum sodium concentration after therapy. Guidelines also have evaluated the use of vasopressin receptor antagonists as alternatives or supplements to standard therapies. This single-center retrospective study from The Methodist Hospital (TMH) compared the effect of HS and conivaptan intervention in the management of 49 patients with hyponatremia from January 2009 through November 2010. Demographics, volume status, medical history, medication data, and serum sodium concentration correction over 48 hours were analyzed. No significant difference was noted with regard to age, ethnicity, gender, volume status, use of medications known to cause hyponatremia, or comorbidities. Baseline serum sodium concentration was not significantly different between HS (120.5 ± 3.8 mEq/L) and conivaptan (118.3 ± 6.7 mEq/L) groups. Regardless of whether the patient was euvolemic or hypervolemic, no significant difference was noted in serum sodium concentration at 4, 12, 24, or 48 hours after initiation of treatment or in frequency of over-correction between groups. This study compares the effect of HS to conivaptan intervention in the management of hyponatremia. No significant differences were identified in adherence to treatment guidelines. Further, based on this small retrospective study, neither agent poses a significant risk of over-correction at 4, 24, or 48 hours of therapy.
View details for PubMedID 23519387
Pilot Study Comparing Total Intravenous Anesthesia to Inhalational Anesthesia in Endoscopic Sinus Surgery: Novel Approach of Blood Flow Quantification
ANNALS OF OTOLOGY RHINOLOGY AND LARYNGOLOGY
2012; 121 (11): 725-732
We compared anesthesia with sevoflurane-remifentanil hydrochloride (SR) to total intravenous anesthesia with propofol-remifentanil hydrochloride (PR) in patients undergoing endoscopic sinus surgery for chronic rhinosinusitis in terms of sinonasal mucosal blood flow, the surgical field visualization score, and blood loss.We performed a double-blinded prospective study at a tertiary care center in 23 adults scheduled to undergo endoscopic sinus surgery for chronic rhinosinusitis. The patients were randomized to receive SR or PR. The sinonasal mucosal blood flow was measured by optical rhinometry. The surgical field visualization score was based on the Boezaart scale.The groups had similar clinical characteristics. During the 60- to 90-minute and 90- to 120-minute operative time windows, the blood flow was significantly greater in the PR group than in the SR group (p = 0.04 and p = 0.03, respectively). The amounts of blood loss in the PR and SR groups were 152.9 +/- 161.3 mL and 355.9 +/- 393.4 mL, respectively (p = 0.12). The median ratios of the surgical field visualization score to the number of sinuses operated on in the PR and SR groups were 2.1 and 1.8, respectively (p = 0.52).The intraoperative blood flow, as determined by optical rhinometry, was significantly greater with anesthesia with PR than with anesthesia with SR, 1 hour into the procedure; however, this difference did not translate into differences in the amounts of operative blood loss or in the surgical field visualization scores.
View details for Web of Science ID 000311468000005
View details for PubMedID 23193905
- Clinical evaluation of the C-MAC D-Blade videolaryngoscope in severely obese patients: a pilot study BRITISH JOURNAL OF ANAESTHESIA 2012; 109 (4): 647-648
Prevalence of Bipolar Disorder and Schizophrenia in Houston Outreach Medicine, Education, and Social Services (HOMES) Clinic Patients: Implications for Student-Managed Clinics for Underserved Populations
2012; 87 (5): 656-661
Psychiatric conditions require aggressive management that is challenging to provide in free clinics. The purpose of this study was to determine the prevalence of certain mental illnesses and comorbid conditions among the patients of a student-managed free clinic for the homeless.The authors conducted a retrospective analysis of the records of patients who visited the student-run Houston Outreach Medicine, Education, and Social Services (HOMES) Clinic from May 2007 through May 2008. They assessed the prevalence of bipolar disorder and schizophrenia among patients. They compared demographics, health insurance status, comorbid medical conditions, and social habit data of patients with these mental illnesses with those of other clinic patients.Of 286 patients (74.5% male, mean age 45.8 years), 25 (8.7%) had a diagnosis of schizophrenia and 45 (15.7%) had bipolar disorder. Compared with other clinic patients, patients with bipolar disorder or schizophrenia were less likely to be male (P < .0001) and were more likely to have publicly funded insurance (P = .024). They were also more likely to have certain comorbid conditions, including asthma (P = .0004), seizures (P = .0007), kidney disease (P = .01), and heart disease (P = .02).The high prevalence of these mental illnesses combined with the increased burden of medical comorbidity among HOMES Clinic patients has implications for student-managed free clinics, which often operate on limited budgets. Strategies for providing care for these patients in this setting include integrated care, street medicine, and case management.
View details for DOI 10.1097/ACM.0b013e31824d4540
View details for Web of Science ID 000303384700029
View details for PubMedID 22450177
- Toward a Better Understanding of the Retention of Physician-Scientists in the Career Pipeline ACADEMIC MEDICINE 2012; 87 (4): 390-391
2012; 108 (4)
The prevalence rate of childhood obesity in Houston exceeds the national figures. Nutrition Mission, a 14-week health promotion and education intervention, was conducted to determine its feasibility and whether it would increase the nutrition and exercise (NE) knowledge of students in an elementary school. This novel student-initiated program used 44 medical students as volunteer instructors in 3 fifth-grade classrooms in a Houston, Texas, elementary school, in which most of the 35 students were socioeconomically disadvantaged and members of ethnic minorities. Research subjects completed pretests and posttests containing demographic, lifestyle, and knowledge-based multiple-choice questions regarding NE content. The Nutrition Mission intervention consisted of weekly programs between September 2007 and December 2007. Outcomes were measured by responses to NE lifestyle and knowledge questions. We found a significant increase in NE knowledge as a result of the intervention (68.1% compared with 78.1%, P<0.001). Subjects' gender and ethnicity affected responses to 2 lifestyle and 3 knowledge questions. The Nutrition Mission showed that a 14-week health promotion and education intervention conceptualized and implemented by medical students is feasible and can improve elementary school students' knowledge of NE. Future studies will include student volunteers from other health care professions and assess whether improved knowledge contributes to improved measurable health outcomes.
View details for PubMedID 22714889
Intraoperative conversion to open technique: is informed consent implied?
journal of clinical ethics
2012; 23 (1): 60-67
This case raises issues regarding the anesthesia and surgical components of preoperative informed consent and the differing views of anesthesiologists and surgeons with regards to informed consent, in the context of conversion to open surgery from a minimally invasive approach.
View details for PubMedID 22462385
- Modified criteria for determining cardiometabolic syndrome in Asian Indians living in the USA: Report from the diabetes among Indian Americans national study INTERNATIONAL JOURNAL OF CARDIOLOGY 2012; 155 (2): 343-345
Single-incision versus conventional laparoscopic sigmoid colectomy: a case-matched series
SURGICAL ENDOSCOPY AND OTHER INTERVENTIONAL TECHNIQUES
2012; 26 (1): 96-102
Single-incision laparoscopic surgery is an emerging modality that has proven to be safe and feasible for colon resection in multiple case reports and series. Nonetheless, comparative analyses with established techniques are limited in the published literature. We evaluated the efficacy of single-incision laparoscopic colectomy (SILC) for the treatment of sigmoid disease through a matched-case comparison with conventional laparoscopic colectomy (CLC).Twenty patients who underwent single-incision laparoscopic sigmoid resection for benign or malignant disease between July 2009 and September 2010 were matched to patients who underwent conventional laparoscopic sigmoid colectomy. Demographic, intraoperative, and postoperative data were assessed.Twenty SILC and CLC cases each were paired based on gender (p < 1.0), age (p < 0.47), pathology (p < 1.0), and surgical procedure (p < 1.0). Ten patients (50%) in the SILC group and eight patients (40%) in the CLC group had a history of prior abdominal surgery (p < 0.53). There were no conversions to open surgery; however, one SILC procedure (5%) required conversion to CLC (p < 0.31). There was no significant difference in mean operating time between groups (p < 0.80). Mean estimated blood loss was significantly lower for SILC compared to CLC (p < 0.007). Mean lymph node extraction was comparable between groups in the subset of patients with malignant disease (p < 0.68). Two postoperative complications were encountered in each group. The mean length of hospital stay for SILC and CLC was 3.2 ± 1.0 and 3.8 ± 2.1 days, respectively (p < 0.25). There were no readmissions or reoperative interventions in either group.Compared with conventional laparoscopic technique, single-incision laparoscopic surgery results in similar intraoperative and postoperative outcomes. The technique avoids use of multiple trocar sites and may safely be performed in patients with a history of previous abdominal surgery while maintaining a short length of hospital stay and low complication rate.
View details for DOI 10.1007/s00464-011-1833-8
View details for Web of Science ID 000298301300014
View details for PubMedID 21792717
Robotic-assisted laparoscopic surgery for restorative proctocolectomy with ileal J pouch-anal anastomosis
MINIMALLY INVASIVE THERAPY & ALLIED TECHNOLOGIES
2011; 20 (4): 234-239
Restorative proctocolectomy (RP) with ileal pouch-anal anastomosis (IPAA) is the surgical procedure of choice for chronic ulcerative colitis (CUC). Robotic-assisted laparoscopic surgery (RALS) has been shown to have its greatest merits in colorectal procedures involving the pelvis. The aim of this study was to evaluate the safety and feasibility of RP with IPAA using an innovative robotic technique. A total of five consecutive patients underwent RALS RP with IPAA between August 2008 and February 2010. Patient demographics, intraoperative parameters, and postoperative outcomes were tabulated and assessed. Surgery was indicated for medically intractable CUC in three patients (60%), CUC-related dysplasia in one patient (20%) and CUC-related adenocarcinoma in one patient (20%). An ileal pouch-anal anastomosis was successful in all five cases. The mean operative time was 330 min and estimated blood loss was 200 cc. There were no intraoperative complications or conversions. The mean length of hospital stay was 5.6 days and no patients developed major postoperative complications. RALS is an innovative technique offering technical and visual advantages to the colorectal surgeon and can be offered for those who are seeking restorative proctolectomy for chronic ulcerative colitis.
View details for DOI 10.3109/13645706.2010.536355
View details for Web of Science ID 000293245900006
View details for PubMedID 21417830
Xenon exposure in the neonatal rat brain: effects on genes that regulate apoptosis
2011; 77 (6): 571-578
In the developing rodent brain, exposure to volatile anesthetics causes widespread neuronal apoptosis in several regions of the brain. Increasing evidence points to a possible neuroprotective role for the anesthetic gas xenon, following neuronal injury. To address this gap in understanding, we explored the transcriptional consequences of xenon in the brains of postnatal day 7 (P7) rats exposed to xenon compared to those of air-breathing animals, with particular emphasis on the mRNA transcript levels of Akt and c-Jun N-terminal kinase kinase 1 (JNKK1), which are important for cell survival and the activation of extrinsic neuroapoptotic pathways, respectively.P7 Sprague/Dawley rats were exposed to air (75% nitrogen, 25% oxygen) or xenon (75% xenon, 25% oxygen) for 120 min (N=6/group). Forebrains were harvested for reverse transcription polymerase chain reaction, which enabled quantification of Akt and JNKK1 mRNA transcripts. Suppression subtractive hybridization was used to explore the "genetic signature" of xenon exposure.Compared to control air-breathing animals, xenon-breathing rats exhibited a 0.7-fold decrease in Akt mRNA expression (P<0.01) and a 1.6-fold increase in JNKK1 mRNA levels (P<0.05).The concomitant decrease in the Akt mRNA expression level and increase in the JNKK1 mRNA transcript level provide evidence that xenon has a neuroapoptotic effect in the developing rodent forebrain. Given these results, further study into the paradoxical neuroprotective and neuroapoptotic effects of xenon is warranted.
View details for Web of Science ID 000292058300004
View details for PubMedID 21617619
Single-incision laparoscopic colectomy: outcomes of an emerging minimally invasive technique
INTERNATIONAL JOURNAL OF COLORECTAL DISEASE
2011; 26 (6): 761-767
Single-incision laparoscopic colectomy (SILC) is an emerging procedure in the field of minimally invasive colon and rectal surgery. The purpose of this study was to evaluate the safety and feasibility of this procedure.Between July 2009 and April 2010, SILC was performed for 35 patients presenting with pathology of the colon. Surgical procedures included right hemicolectomy, sigmoid resection, and total colectomy. Demographic data, intraoperative parameters, and short-term postoperative outcomes were assessed.Thirty two of the 35 patients (91.4%) underwent successful completion of SILC while 3 patients required laparoscopic modifications. The mean incision length was 3.4 cm with a range of 2-6 cm. The mean total operative time (OT) for right, left, and total colectomies was 158.8 ± 31.8 min, 127.0 ± 37.1 min, and 216.3 ± 72.6 min, respectively. Overall, the OT was not significantly different between patients with a body mass index (BMI) ≥ 25 kg/m(2) (147.9 ± 47.9 min) compared to those with a BMI <25 kg/m(2) (123.1 ± 40.9 min). In the subset of patients with malignant disease, the mean lymph node extraction was 23.5 ± 12.0 and all margins were negative. There were no intraoperative complications, and the overall mean length of hospital stay was 2.9 ± 1.0 days (range 2-6 days). The postoperative morbidity rate was 11.4%.Single-incision laparoscopic colectomy is a safe and feasible procedure for benign and malignant diseases of the colon. This modality can be successfully applied for various colorectal procedures without conversion to open surgery, resulting in a short length of hospital stay and a minimal short-term complication rate.
View details for DOI 10.1007/s00384-011-1185-9
View details for Web of Science ID 000290808900011
View details for PubMedID 21445554
Learning curve for robotic-assisted laparoscopic colorectal surgery
SURGICAL ENDOSCOPY AND OTHER INTERVENTIONAL TECHNIQUES
2011; 25 (3): 855-860
Robotic-assisted laparoscopic surgery (RALS) is evolving as an important surgical approach in the field of colorectal surgery. We aimed to evaluate the learning curve for RALS procedures involving resections of the rectum and rectosigmoid.A series of 50 consecutive RALS procedures were performed between August 2008 and September 2009. Data were entered into a retrospective database and later abstracted for analysis. The surgical procedures included abdominoperineal resection (APR), anterior rectosigmoidectomy (AR), low anterior resection (LAR), and rectopexy (RP). Demographic data and intraoperative parameters including docking time (DT), surgeon console time (SCT), and total operative time (OT) were analyzed. The learning curve was evaluated using the cumulative sum (CUSUM) method.The procedures performed for 50 patients (54% male) included 25 AR (50%), 15 LAR (30%), 6 APR (12%), and 4 RP (8%). The mean age of the patients was 54.4 years, the mean BMI was 27.8 kg/m(2), and the median American Society of Anesthesiologists (ASA) classification was 2. The series had a mean DT of 14 min, a mean SCT of 115.1 min, and a mean OT of 246.1 min. The DT and SCT accounted for 6.3% and 46.8% of the OT, respectively. The SCT learning curve was analyzed. The CUSUM(SCT) learning curve was best modeled as a parabola, with equation CUSUM(SCT) in minutes equal to 0.73 × case number(2) - 31.54 × case number - 107.72 (R = 0.93). The learning curve consisted of three unique phases: phase 1 (the initial 15 cases), phase 2 (the middle 10 cases), and phase 3 (the subsequent cases). Phase 1 represented the initial learning curve, which spanned 15 cases. The phase 2 plateau represented increased competence with the robotic technology. Phase 3 was achieved after 25 cases and represented the mastery phase in which more challenging cases were managed.The three phases identified with CUSUM analysis of surgeon console time represented characteristic stages of the learning curve for robotic colorectal procedures. The data suggest that the learning phase was achieved after 15 to 25 cases.
View details for DOI 10.1007/s00464-010-1281-x
View details for Web of Science ID 000287749900027
View details for PubMedID 20734081
View details for PubMedCentralID PMC3044842
A Three-Arm (Laparoscopic, Hand-Assisted, and Robotic) Matched-Case Analysis of Intraoperative and Postoperative Outcomes in Minimally Invasive Colorectal Surgery
DISEASES OF THE COLON & RECTUM
2011; 54 (2): 144-150
Robotic-assisted laparoscopic surgery is an emerging modality in the field of minimally invasive colorectal surgery. However, there is a dearth of data comparing outcomes with other minimally invasive techniques. We present a 3-arm (conventional, hand-assisted, and robotic) matched-case analysis of intraoperative and short-term outcomes in patients undergoing minimally invasive colorectal procedures.Between August 2008 and October 2009, 70 robotic cases of the rectum and rectosigmoid were performed. Thirty of these were organized into triplets with conventional and hand-assisted cases based on the following 6 matching criteria: 1) surgeon; 2) sex; 3) body mass index; 4) operative procedure; 5) pathology; and 6) history of neoadjuvant therapy in malignant cases. Demographics, intraoperative parameters, and postoperative outcomes were assessed. Pathological outcomes were analyzed in malignant cases. Data were stratified by postoperative diagnosis and operative procedure.There was no significant difference in intraoperative complications, estimated blood loss (126.1 ± 98.5 mL overall), or postoperative morbidity and mortality among the groups. Robotic technique required longer operative time compared with conventional laparoscopic (P < .01) and hand-assisted (P < .001) techniques; however, this difference was not maintained in cases with low pelvic anastomoses. The overall mean length of stay was 3.3 ± 1.8 days with no significant difference between the groups. Pathological analysis of malignant cases revealed a median lymph node extraction of 17 with no significant difference among the 3 modalities.In this 3-arm case-matched series, the robotic approach results in short-term outcomes comparable to conventional and hand-assisted laparoscopic approaches for benign and malignant diseases of the rectum and rectosigmoid. With 3-dimensional visualization, additional freedom of motion, and improved ergonomics, this enabling technology may play an important role when performing colorectal procedures involving the pelvic anatomy.
View details for DOI 10.1007/DCR.0b013e3181fec377
View details for Web of Science ID 000286180000004
View details for PubMedID 21228660
Diagnostic nuclear medicine in the ED
AMERICAN JOURNAL OF EMERGENCY MEDICINE
2011; 29 (1): 91-101
Although the decision to use nuclear medicine (NM) modalities in the acute care setting is limited by several factors, there are instances in which the use of NM techniques can provide elegant and efficient solutions to otherwise expensive and resource consuming situations. Herein, we describe the indications and NM techniques used for the evaluation of low-risk patients with chest pain, suspected pulmonary embolus, acute cholecystitis, gastrointestinal bleeding, acute scrotum, and the radiographically occult fracture.
View details for DOI 10.1016/j.ajem.2009.03.008
View details for Web of Science ID 000285400500016
View details for PubMedID 20825918
Robotic-assisted laparoscopic surgery for recurrent diverticulitis: experience in consecutive cases and a review of the literature
SURGICAL ENDOSCOPY AND OTHER INTERVENTIONAL TECHNIQUES
2011; 25 (1): 199-206
Robotic-assisted laparoscopic surgery has recently gained enthusiasm for application in colorectal surgery. We present the safety and feasibility of using the da Vinci® robotic system for the surgical treatment of sigmoid diverticulitis.Between August 2008 and November 2009, robotic-assisted laparoscopic anterior rectosigmoid resection (RALS-AR) for diverticulitis was performed in 24 consecutive patients. Demographic data, intraoperative parameters, and postoperative outcomes were assessed.RALS-AR was performed in 14 male (58.3%) and 10 female (41.7%) patients with a diagnosis of recurrent diverticulitis. The mean patient age and BMI were 49.8 ± 9.3 years (range = 30-62 years) and 29.9 ± 6.3 kg/m(2) (range = 15.9-46.9 kg/m(2)), respectively. Disease stratification identified 15 cases of uncomplicated (62.5%) and 9 cases of complicated (37.5%) disease. The procedures required 14.1 ± 6.7 min (range = 6-30 min) for robotic docking, 100.5 ± 31.0 min (range = 50-180 min) for surgeon console time, and 224.2 ± 47.1 min (range = 150-330 min) for the total operative time. Robotic docking and surgeon console time represented 51.9% of the total operative time. A primary colorectal anastomosis was fashioned with avoidance of colostomy in all patients. There were no significant intraoperative complications, and none of the procedures required conversion to open, hand-assisted, or conventional laparoscopic technique. The length of hospital stay was 3.4 ± 2.6 days (range = 2-14 days), and the postoperative complication rate was 12.5% (n = 3). There were no anastomotic leaks, secondary surgical interventions, or hospital readmissions.Robotic-assisted laparoscopic technique is a safe and feasible option for the surgical treatment of diverticulitis. The approach may be offered to patients with uncomplicated or complicated disease, and it results in a short hospital stay and low complication rate.
View details for DOI 10.1007/s00464-010-1159-y
View details for Web of Science ID 000285754000030
View details for PubMedID 20567850
Patient Satisfaction and Symptomatic Outcomes Following Stapled Transanal Rectal Resection for Obstructed Defecation Syndrome
JOURNAL OF SURGICAL RESEARCH
2011; 165 (1): E15-E21
Obstructed defecation syndrome (ODS) is recognized as a functional (e.g., anismus) and anatomic (e.g., rectocele and rectal intussusception) defecatory disorder of the pelvic floor. This study was designed to evaluate outcomes and patient satisfaction following stapled transanal rectal resection (STARR) for the surgical treatment of ODS.Between May 2006 and July 2009, 37 patients underwent STARR for correction of ODS secondary to rectocele and internal intussusception. Demographic data and postoperative outcomes were tabulated. Symptomatic outcomes were assessed by comparing pre- and postoperative subsets of the Wexner constipation scoring system, and quality outcomes were evaluated with patient satisfaction surveys.Thirty-seven female patients with a mean age of 52.9 ± 11.2 y underwent STARR. All patients had clinically significant rectocele as evidenced on defecography and 81.1% had concomitant internal rectal intussusception. Postoperative complications occurred in 13 patients (35.1%). Two of these patients required re-intervention: dilation of stricture and transanal excision of staple granuloma. Mean quality of life follow-up occurred at 20.3 ± 6.5 mo (median: 20 mo, range: 9-36 mo). Mean preoperative and postoperative constipation subset scores were 11.1 ± 3.6 and 4.6 ± 3.9, respectively (P < 0.00001). Overall outcome was reported as "excellent" or "good" in 71.9% of patients, "adequate" in 15.6%, and "poor" in 12.5%. When asked if they would undergo the procedure again, 81.3% responded affirmatively.The STARR procedure results in improved symptomatic outcomes, high patient satisfaction, and an acceptable complication rate. In selected patients, this minimally invasive approach was an acceptable procedure for the surgical correction of ODS secondary to rectocele and intussusception.
View details for DOI 10.1016/j.jss.2010.07.045
View details for Web of Science ID 000285136000002
View details for PubMedID 21067778
Single-Incision Versus Hand-Assisted Laparoscopic Colectomy: A Case-Matched Series
JOURNAL OF GASTROINTESTINAL SURGERY
2010; 14 (12): 1875-1880
Single-incision laparoscopic colorectal surgery is an emerging modality. We incorporated this technique as an alternative to hand-assisted laparoscopic surgery. We investigated intraoperative and short-term outcomes following single-incision laparoscopic colectomy compared with hand-assisted laparoscopic colectomy.Between July and November 2009, single-incision colorectal procedures were performed and matched to hand-assisted procedures based on five criteria: gender, age, body mass index, pathology, and type of procedure. Demographic, intraoperative, and postoperative data were assessed.Twenty-four pairs of patients with a mean age of 55.1 years and mean body mass index of 28.5 kg/m(2) were matched. The majority of cases (79.2%) were right hemicolectomies. The ranges of incision length were 2-6 cm (single incision) and 5-11 cm (hand-assisted). Mean operating time was significantly longer for single-incision procedures (143.2 min) compared with hand-assisted procedures (112.8 min), p < 0.0004. There was no significant difference in the groups regarding conversions or intraoperative complications (p < 0.083 and p < 1.0, respectively). Mean length of stay for the single-incision approach (2.7 days) was significantly shorter compared with the hand-assisted approach (3.3 days), p < 0.02.Single-incision laparoscopic colectomy is a safe and feasible alternative to hand-assisted laparoscopic surgery. Although the technique required longer operative time, it resulted in smaller incision size and significantly shorter length of hospitalization.
View details for DOI 10.1007/s11605-010-1355-z
View details for Web of Science ID 000285070300003
View details for PubMedID 20922576
Robotic-assisted laparoscopic abdominoperineal resection for anal cancer: feasibility and technical considerations
INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY
2010; 6 (4): 399-404
Robotic-assisted laparoscopic surgery is an emerging technology that may prove advantageous for complex colorectal procedures involving the irradiated pelvis, such as abdominoperineal resection for recurrent anal cancer. The authors' initial experience is presented, with assessment of feasibility, safety, and oncologic principles.Over a 6 month period, five abdominoperineal resections were performed using the da Vinci® robot for recurrent anal cancer in patients initially treated with definitive chemoradiation therapy. Demographics, intraoperative parameters, pathology, and outcomes were assessed.Five patients underwent surgery with a mean age of 58.8 years and body mass index of 24.9 kg m(-2) . The interval between chemoradiation and salvage APR was 14.2 ± 10.0 months. Operative time was 204 ± 39.1 min with robotic docking time 12.2 ± 2.8 min and console time 93.0 ± 24.9 min. The mean estimated blood loss was 150 cc and there were no intraoperative complications. The mean hospital length of stay was 5.4 days. Pathology analysis revealed that all surgical margins were adequate. There was one postoperative complication consisting of a seroma.Robotic-assisted laparoscopic surgery for anal cancer was found to be a safe and feasible procedure. It facilitated enhanced visualization and dissection through deep irradiated pelvic structures.
View details for DOI 10.1002/rcs.348
View details for Web of Science ID 000285223000005
View details for PubMedID 20827795
Single-incision laparoscopic right hemicolectomy: safety and feasibility in a series of consecutive cases
SURGICAL ENDOSCOPY AND OTHER INTERVENTIONAL TECHNIQUES
2010; 24 (10): 2613-2616
Single-incision laparoscopic colectomy (SILC) is rapidly emerging in the field of minimally invasive colon and rectal surgery. This report presents the safety and feasibility of performing SILC right hemicolectomy with the SILS™ Port Multiple Instrument Access Port.Between July 2009 and October 2009, SILC right hemicolectomy was performed for 13 consecutive, unselected patients presenting with benign or malignant pathology. Demographic data, intraoperative parameters, and postoperative outcomes were assessed.For 11 of the 13 patients (84.6%), the SILC procedure was performed with a mean incision length of 3.1 ± 1.1 cm (range, 2.5-6.0 cm) and a mean operative time of 131.5 ± 36.2 min (range, 79-180 min). Two cases required conversion to hand-assisted technique. Overall, the operative time was found to be significantly longer for the patients with a body mass index (BMI) greater than 25 kg/m(2) (152.1 ± 26.6 min) compared with the patients with a BMI less than 25 kg/m(2) (93.3 ± 11.6 min) (p < 0.002). For the subset of patients with malignant disease (five adenocarcinomas and one carcinoid), the mean number of lymph nodes extracted was 26.7 ± 14.5. There were no intraoperative complications, and the overall mean hospital stay was 2.5 ± 0.7 days (range, 2-4 days). One postoperative complication occurred (7.7%).The SILC procedure is a safe and feasible method for benign and malignant diseases requiring a right hemicolectomy. This method results in a low complication rate and a short postoperative hospital stay.
View details for DOI 10.1007/s00464-010-1017-y
View details for Web of Science ID 000282181500038
View details for PubMedID 20364353
Single Incision Laparoscopic-Assisted Right Hemicolectomy: Technique and Application (With Video)
SURGICAL LAPAROSCOPY ENDOSCOPY & PERCUTANEOUS TECHNIQUES
2010; 20 (5): E146-E149
Most commonly employed for surgery of the gallbladder and appendix, single-incision laparoscopic surgery (SILS) is rapidly evolving in the field of minimally invasive surgery. The purpose of this report is to describe the feasibility and technique for SILS right hemicolectomy, which has not been widely reported.We describe a laparoscopic right hemicolectomy with a modified single-incision technique for the management of a precancerous polyp of the ascending colon.The procedure was successfully performed in 105 minutes using 3 transumbilical trocars placed through a single port, and readily available nonarticulating laparoscopic instruments. In addition, we review the literature of SILS procedures involving the colon and discuss differences between our approach and those reported elsewhere.SILS is a feasible modality applicable to minimally invasive surgery of the colon and can offer benefits to the patient.
View details for DOI 10.1097/SLE.0b013e3181ee039f
View details for Web of Science ID 000283486000001
View details for PubMedID 20975489
Robotic-Assisted Laparoscopic "Salvage" Rectopexy for Recurrent Ileoanal J-Pouch Prolapse
GASTROENTEROLOGY RESEARCH AND PRACTICE
Total restorative proctocolectomy with ileal pouch-anal anastomosis (RP/IPAA) has become the standard of care for the surgical treatment of ulcerative colitis. Despite its correlation with an excellent quality of life and favorable long-term outcomes, RP/IPAA has been associated with several complications. Prolapse of the ileoanal pouch is a rare and debilitating complication that should be considered in the differential diagnosis of pouch failure. Limited data exist regarding the prevalence and treatment of pouch prolapse. We present the case of a recurrent J-pouch prolapse treated with a novel minimally invasive "salvage" approach involving a robotic-assisted laparoscopic rectopexy with mesh.
View details for DOI 10.1155/2010/790462
View details for Web of Science ID 000284930100001
View details for PubMedID 20414343
View details for PubMedCentralID PMC2855981
Management of extensive squamous cell carcinoma on the site of radiation-induced dermatitis with severe fibrosis: a case report
J Radiother Pract
2010; 9 (2): 125-8
View details for DOI 10.1017/S1460396909990318
- Consider using diffusion tensor imaging in Geron phase I trial. AJNR. American journal of neuroradiology 2009; 30 (7): E97-?
- Letter by Patel Regarding Article, "A Primer in Longitudinal Data Analysis" CIRCULATION 2009; 120 (4): E25-E25
Effect of VEGF Treatment on the Blood-Spinal Cord Barrier Permeability in Experimental Spinal Cord Injury: Dynamic Contrast-Enhanced Magnetic Resonance Imaging
JOURNAL OF NEUROTRAUMA
2009; 26 (7): 1005-1016
Compromised blood-spinal cord barrier (BSCB) is a factor in the outcome following traumatic spinal cord injury (SCI). Vascular endothelial growth factor (VEGF) is a potent stimulator of angiogenesis and vascular permeability. The role of VEGF in SCI is controversial. Relatively little is known about the spatial and temporal changes in the BSCB permeability following administration of VEGF in experimental SCI. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) studies were performed to noninvasively follow spatial and temporal changes in the BSCB permeability following acute administration of VEGF in experimental SCI over a post-injury period of 56 days. The DCE-MRI data was analyzed using a two-compartment pharmacokinetic model. Animals were assessed for open field locomotion using the Basso-Beattie-Bresnahan score. These studies demonstrate that the BSCB permeability was greater at all time points in the VEGF-treated animals compared to saline controls, most significantly in the epicenter region of injury. Although a significant temporal reduction in the BSCB permeability was observed in the VEGF-treated animals, BSCB permeability remained elevated even during the chronic phase. VEGF treatment resulted in earlier improvement in locomotor ability during the chronic phase of SCI. This study suggests a beneficial role of acutely administered VEGF in hastening neurobehavioral recovery after SCI.
View details for DOI 10.1089/neu.2008.0860
View details for Web of Science ID 000267965500006
View details for PubMedID 19226205
Blood-spinal cord barrier permeability in experimental spinal cord injury: dynamic contrast-enhanced MRI
NMR IN BIOMEDICINE
2009; 22 (3): 332-341
After a primary traumatic injury, spinal cord tissue undergoes a series of pathobiological changes, including compromised blood-spinal cord barrier (BSCB) integrity. These vascular changes occur over both time and space. In an experimental model of spinal cord injury (SCI), longitudinal dynamic contrast-enhanced MRI (DCE-MRI) studies were performed up to 56 days after SCI to quantify spatial and temporal changes in the BSCB permeability in tissue that did not show any visible enhancement on the post-contrast MRI (non-enhancing tissue). DCE-MRI data were analyzed using a two-compartment pharmacokinetic model. These studies demonstrate gradual restoration of BSCB with post-SCI time. However, on the basis of DCE-MRI, and confirmed by immunohistochemistry, the BSCB remained compromised even at 56 days after SCI. In addition, open-field locomotion was evaluated using the 21-point Basso-Beattie-Bresnahan scale. A significant correlation between decreased BSCB permeability and improved locomotor recovery was observed.
View details for DOI 10.1002/nbm.1343
View details for Web of Science ID 000264578200012
View details for PubMedID 19023867
- Averting the proliferation of acronymophilia. in dermatology: Effectively avoiding ADCOMSUBORDCOMPHIBSPAC JOURNAL OF THE AMERICAN ACADEMY OF DERMATOLOGY 2009; 60 (2): 340-344
The effect of dental artifacts, contrast media, and experience on interobserver contouring variations in head and neck anatomy
Am J Clin Oncol
2007; 30 (2): 191-8
View details for DOI 10.1097/01.coc.0000256704.58956.45
Cultural humility in medicine: beyond the K-20 pipeline.
2006; 102 (4): 7-?
View details for PubMedID 17128753
Sinusoidal modeling of ictal activity along a thalamus-to-cortex seizure pathway I: New coherence approaches
ANNALS OF BIOMEDICAL ENGINEERING
2004; 32 (9): 1252-1264
Understanding associations in neuronal circuitry is critical for tracing epilepsy pathways. Two new methods of measuring coherence between field potentials and EEG channels are proposed for modeling the level of linear association between channels during epileptic seizures. These methods rely upon modeling the repetitive clonic seizure activity as a sum of sinusoids with varying degrees of phase locking. Estimating the amplitude of sinusoids from correlation and cross-correlation time domain data, we can find the coherences from a ratio of these amplitudes. One method utilizes amplitude finding from the multiple signal classification (MUSIC) technique. The other method uses alterations in amplitude of individual sinusoids and their ratios in a matrix pencil equation formed from cross- and auto-correlation matrices. The corresponding generalized eigenvalues of these equations form the coherence ratios. This utilizes the estimation of signal parameters using rotational invariance techniques (ESPRIT) algorithm to arrive at coherence amplitude ratios. Simulations illustrate that the MUSIC method provides better noise immunity as it out-performs the conventional Fourier transform-based method for coherence estimation. Both coherence estimators reflect presence of sinusoidal components that are propagated or not propagated along a particular transmission pathway. We illustrate the value of both methods by examining the strength of correlation between seizure EEG from specific thalamic nuclei and cortex in a rodent model of generalized epilepsy. The pentylenetetrazol (PTZ) chemoconvulsant model in rats reflects selective activation of the anterior thalamic nucleus. Using both methods, this neuronal element has much larger coherence with cortex than another thalamic region, the posterior thalamus (p < 0.05). These methods isolate the unique contribution of anterior thalamus in the formation of an ictal network and corroborate earlier conventional or periodogram techniques.
View details for Web of Science ID 000223549700008
View details for PubMedID 15493512
Prediction of PTZ-induced seizures using wavelet-based residual entropy of cortical and subcortical field potentials
IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING
2003; 50 (5): 640-648
Our proposed algorithm for seizure prediction is based on the principle that seizure build-up is always preceded by constantly changing bursting levels. We use a novel measure of residual subband wavelet entropy (RSWE) to directly estimate the entropy of bursts, which is otherwise obscured by the ongoing background activity. Our results are obtained using a slow infusion anesthetized pentylenetetrazol (PTZ) rat model in which we record field potentials (FPs) from frontal cortex and two thalamic areas (anterior and posterior nuclei). In each frequency band, except for the theta-delta frequency bands, we observed a significant build-up of RSWE from the preictal period to the first ictal event (p < or = 0.05) in cortex. Significant differences were observed between cortical and thalamic RSWE (p < or = 0.05) subsequent to seizure development. A key observation is the twofold increase in mean cortical RSWE from the preictal to interictal period. Exploiting this increase, we develop a slope change detector to discern early acceleration of entropy and predict the approaching seizure. We use multiple observations through sequential detection of slope changes to enhance the sensitivity of our prediction. Using the proposed method applied to a cohort of four rats subjected to PTZ infusion, we were able to predict the first seizure episode 28 min prior to its occurrence.
View details for DOI 10.1109/TBME.2003.810683
View details for Web of Science ID 000182870900012
View details for PubMedID 12769440
Wilms' tumor suppressor gene (WT1) is expressed in primary breast tumors despite tumor-specific promoter methylation
2001; 61 (3): 921-925
We analyzed Wilms' tumor suppressor 1 (WT1) expression and its regulation by promoter methylation in a panel of normal breast epithelial samples and primary carcinomas. Contrary to previous reports, WT1 protein was strongly expressed in primary carcinomas (27 of 31 tumors) but not in normal breast epithelium (1 of 20 samples). Additionally, the WT1 promoter was methylated in 6 of 19 (32%) primary tumors, which nevertheless expressed WT1. The promoter is not methylated in normal epithelium. Thus, although tumor-specific methylation of WT1 is established in primary breast cancer at a low frequency, other transcriptional regulatory mechanisms appear to supercede its effects in these tumors. Our results demonstrate expression of WT1 in mammary neoplasia, and that WT1 may not have a tumor suppressor role in breast cancer.
View details for Web of Science ID 000167020100027
View details for PubMedID 11221883