Honors & Awards
Best Basic/Translational Oral Presentation, Holman Research Day, Stanford University Department of Surgery (2018)
Excellence in Research Award, Surgical Oncology, American College of Surgeons (ACS) Clinical Congress (2018)
Advanced Residency Training at Stanford (ARTS) Program, Stanford University School of Medicine (2017 - present)
NIH Loan Repayment Program (LRP), National Institutes of Health (2017 - present)
Resident Research Award, American College of Surgeons (ACS) (2017 - 2019)
Fall Courses Travel Award, Association of Academic Surgery (AAS) (2017)
The Donald R. Cooper, M.D. Award for Excellence in Surgery, Drexel University College of Medicine (2015)
Women’s Health Scholar, Drexel University College of Medicine (2015)
Fulbright Research Scholarship, U.S. Department of State (2010)
Current Clinical Interests
- Surgical Oncology
Michael Longaker, Longaker Laboratory (7/1/2017)
Doxycycline Reduces Scar Thickness and Improves Collagen Architecture.
Annals of surgery
OBJECTIVE: To investigate the effects of local doxycycline administration on skin scarring.BACKGROUND: Skin scarring represents a major source of morbidity for surgical patients. Doxycycline, a tetracycline antibiotic with off-target effects on the extracellular matrix, has demonstrated antifibrotic effects in multiple organs. However, doxycycline's potential effects on skin scarring have not been explored in vivo.METHODS: Female C57BL/6J mice underwent dorsal wounding following an established splinted excisional skin wounding model. Doxycycline was administered by local injection into the wound base following injury. Wounds were harvested upon complete wound closure (postoperative day 15) for histological examination and biomechanical testing of scar tissue.RESULTS: A one-time dose of 3.90 mM doxycycline (2 mg/mL) within 12 hours of injury was found to significantly reduce scar thickness by 24.8% (P < 0.0001) without compromising tensile strength. The same effect could not be achieved by oral dosing. In doxycycline-treated scar matrices, collagen I content was significantly reduced (P = 0.0317) and fibers were favorably arranged with significantly increased fiber randomness (P = 0.0115). Common culprits of altered wound healing mechanics, including angiogenesis and inflammation, were not impacted by doxycycline treatment. However, engrailed1 profibrotic fibroblasts, responsible for scar extracellular matrix deposition, were significantly reduced with doxycycline treatment (P = 0.0005).CONCLUSIONS: Due to the substantial improvement in skin scarring and well-established clinical safety profile, locally administered doxycycline represents a promising vulnerary agent. As such, we favor rapid translation to human patients as an antiscarring therapy.
View details for DOI 10.1097/SLA.0000000000003172
View details for PubMedID 30585822
Author Correction: Genetic dissection of clonal lineage relationships with hydroxytamoxifen liposomes.
2018; 9 (1): 4411
In the original version of this Article, the authors inadvertently omitted Elizabeth A. Brett, who contributed to the generation of the histology figures, from the author list.This has now been corrected in both the PDF and HTML versions of the Article.
View details for DOI 10.1038/s41467-018-06927-2
View details for PubMedID 30341306
- Acta2, Tnc, and Col24a1 Expression Are Associated with Abdominal Adhesion Formation ELSEVIER SCIENCE INC. 2018: E128
- Nerve-Dependent Mandibular Regeneration by Skeletal Stem Cells in Fracture Repair ELSEVIER SCIENCE INC. 2018: S197
- Reduced Scar Thickness Achieved by Topical Doxycycline Is Mediated by Specific Skin Fibroblast Populations and Not Immune Cell Infiltrate ELSEVIER SCIENCE INC. 2018: S210–S211
- Clonal Analysis of Local Fibroblasts in Wound Healing and Tumor Stroma ELSEVIER SCIENCE INC. 2018: S236
Gastrinomas: Medical or Surgical Treatment.
Endocrinology and metabolism clinics of North America
2018; 47 (3): 577–601
This article reviews the role of surgical and medical management in patients with Zollinger-Ellison syndrome (ZES) due to a gastrin-secreting neuroendocrine tumor (gastrinoma). It concentrates on the status at present but also briefly reviews the changes over time in treatment approaches. Generally, surgical and medical therapy are complementary today; however, in some cases, such as patients with ZES and multiple endocrine neoplasia type 1, the treatment approach remains controversial.
View details for DOI 10.1016/j.ecl.2018.04.009
View details for PubMedID 30098717
- Management of Liver Neuroendocrine Tumors in 2018. JAMA oncology 2018
- Fibroblasts and wound healing: an update. Regenerative medicine 2018
Genetic dissection of clonal lineage relationships with hydroxytamoxifen liposomes.
2018; 9 (1): 2971
Targeted genetic dissection of tissues to identify precise cell populations has vast biological and therapeutic applications. Here we develop an approach, through thepackaging and delivery of 4-hydroxytamoxifen liposomes (LiTMX), that enables localized induction of CreERT2 recombinase in mice. Our method permits precise, in vivo, tissue-specific clonal analysis with both spatial and temporal control. This technology is effective using mice with both specific and ubiquitous Cre drivers in a variety of tissue types, under conditions of homeostasis and post-injury repair, and is highly efficient for lineage tracing and genetic analysis. This methodology is directly and immediately applicable to the developmental biology, stem cell biology and regenerative medicine, and cancer biology fields.
View details for DOI 10.1038/s41467-018-05436-6
View details for PubMedID 30061668
- Incidence and Prognosis of Primary Gastrinomas in the Hepatobiliary Tract JAMA SURGERY 2018; 153 (3): e175083
Axillary reverse mapping with indocyanine green or isosulfan blue demonstrate similar crossover rates to radiotracer identified sentinel nodes
JOURNAL OF SURGICAL ONCOLOGY
2018; 117 (3): 336–40
Sentinel lymph node (SLN) resection is imperative for breast cancer staging. Axillary reverse mapping (ARM) can preserve arm draining nodes and lymphatics during surgery. ARM is generally performed with isosulfan blue (ISB), restricting its use for concurrent SLN biopsy. Indocyanine green (ICG) could serve as an alternative to ISB for ARM procedures.SLN mapping and biopsy was performed via periareolar injection of 99 technetium-sulfur colloid (99m TcSc, TSC). ISB and ICG were injected in the upper arm. Blue-stained lymphatics or nodes were visualized in the axilla; ICG was identified using the SPY Elite® system.Twenty-three patients underwent SLN biopsy with or without axillary node dissection and ARM procedures. Twenty of these patients had at least one hot node; 12 patients had SLNs that were only hot, 6 hot/blue/fluorescent, and 2 hot/fluorescent. Overall, crossover of ARM agents with SLNs occurred in 8 cases. Inspection of the axillary cavity after SLN biopsy revealed fluorescent lymphatics and nodes remaining in 14 and 7 patients, respectively. Blue lymphatics and blue nodes were detected in fewer cases.Nearly one-third of patients showed crossover between breast and arm draining nodes, which provides insight as to why some patients develop lymphedema symptoms after SLN biopsy. ICG and ISB identify similar numbers of SLNs. As such ICG could substitute for ISB in ARM procedures.
View details for DOI 10.1002/jso.24859
View details for Web of Science ID 000427584100001
View details for PubMedID 29228459
Management of Chronic Wounds—2018
View details for DOI 10.1001/jama.2018.12426
Endoscopic Excision of Benign Facial Masses in Children: A Review of Outcomes.
Journal of laparoendoscopic & advanced surgical techniques. Part A
Benign masses of the eyebrow and forehead are common in pediatric patients and can result in facial asymmetry, discomfort, or super-infection. Excision is classically conducted via an incision directly over the mass, which can produce sub-optimal cosmesis. Recently, an endoscopic approach using pediatric brow-lift equipment has been adopted. We reviewed our center's experience with endoscopic removal of benign facial lesions and compared these cases with an equivalent series of open cases.A retrospective chart review was conducted to identify pediatric cases of endoscopic and open removal of benign eyebrow or forehead lesions at our institution from 2009 to 2016. Clinical and cosmetic outcomes were reviewed.A total of 40 endoscopic and 25 open cases of excision of benign facial lesions in children were identified. For the patients who underwent endoscopic excision, the majority (85%) presented with a cyst located at the eyebrow. Histologic examination revealed 36 dermoid cysts (90%), 2 epidermal cysts, and 2 pilomatrixomas. Of the 36 cases with post-operative follow-up, 32 patients (89%) had an uncomplicated recovery with good cosmesis. Two patients had an eyebrow droop that resolved without intervention. One patient had localized numbness overlying the site, but no motor deficits. One patient presented with a recurrent dermoid cyst that required open resection. For the patients who underwent open excision, the majority (52%) had dermoid cysts located at the eyebrow. Of the 22 cases with follow-up, 20 of the patients had an uncomplicated recovery (90%). Comparing the rate of complications, there was no statistically significant difference between the two groups (P = 1.0).Endoscopic excision of benign forehead and eyebrow lesions in pediatric patients is feasible and yields excellent cosmetic results. When compared with open excision, complication rates are similar between both approaches and a facial scar can be avoided with an endoscopic approach.
View details for DOI 10.1089/lap.2017.0168
View details for PubMedID 29446701
Surgical Site Infections after Inguinal Hernia Repairs Performed in Low and Middle Human Development Index Countries: A Systematic Review.
Inguinal hernias are a common disorder in low- and middle-human development index countries (LMHDICs). Poor access to surgical care and lack of patient awareness often lead to delayed presentations of incarcerated or strangulated hernias and their associated morbidities. There is a scarcity of data on the baseline incidence of surgical site infections (SSIs) after hernia repair procedures in LMHDICs.We performed a systematic review of the literature describing the incidence and management of SSIs after inguinal hernia repair in LMHDICs. We conducted qualitative and quantitative analyses of manuscripts describing patients undergoing hernia repair to establish a baseline SSI rate for this procedure in these settings.Three hundred twenty-three abstracts were identified after applying search criteria, and 31 were suitable for the quantitative analysis. The overall pooled SSI rate was 4.1 infections/100 open hernia repairs (95% confidence interval [CI] 3.0-5.3 infections/100 open repairs), which is consistent with infection rates from high-human development index countries. A separate subgroup analysis of laparoscopic hernia repairs found a weighted pooled SSI rate of 0.4 infections/100 laparoscopic repairs (95% CI 0-2.4 infections/100 laparoscopic repairs).As surgical access continues to expand in LMHDIC settings, it is imperative to monitor surgical outcomes and ensure that care is provided safely. Establishing a baseline SSI rate for inguinal hernia repairs offers a useful benchmark for future studies and surgical programs in these countries.
View details for DOI 10.1089/sur.2017.154
View details for PubMedID 29048997
Surgical Site Infections after Appendectomy Performed in Low and Middle Human Development-Index Countries: A Systematic Review.
Acute appendicitis is a common surgical emergency worldwide. Early intervention is associated with better outcomes. In low and middle Human Development-Index Countries (LMHDICs), late presentation and poor access to healthcare facilities can contribute to greater illness severity and higher complication rates, such as post-operative surgical site infections (SSIs). The current rate of SSIs post-appendectomy in low- and middle-index settings has yet to be described.We performed a systemic review of the literature describing the incidence and management of SSIs after appendectomy in LMHDICs. We conducted qualitative and quantitative analysis of the data in manuscripts describing patients undergoing appendectomy to establish a baseline SSI rate for this procedure in these settings.Four hundred twenty-three abstracts were initially identified. Of these, 35 studies met the criteria for qualitative and quantitative analysis. The overall weighted, pooled SSI rated were 17.9 infections/100 open appendectomies (95% confidence interval [CI] 10.4-25.3 infections/100 open appendectomies) and 8.8 infections/100 laparoscopic appendectomies (95% CI 4.5-13.2 infections/100 laparoscopic appendectomies). The SSI rates were higher in complicated appendicitis and when pre-operative antibiotic use was not specified.Observed SSI rates after appendectomy in LMHDICs are dramatically higher than rates in high Human Development-Index Countries. This is particularly true in cases of open appendectomy, which remains the most common surgical approach in LMHDICs. These findings highlight the need for SSI prevention in LMHDICs, including prompt access to medical and surgical care, routine pre-operative antibiotic use, and implementation of bundled care packages and checklists.
View details for DOI 10.1089/sur.2017.188
View details for PubMedID 29058569
Regression of experimental NIS-expressing breast cancer brain metastases in response to radioiodide/gemcitabine dual therapy
2016; 7 (34): 54811-54824
Treating breast cancer brain metastases (BCBMs) is challenging. Na+/I- symporter (NIS) expression in BCBMs would permit their selective targeting with radioiodide (131I-). We show impressive enhancement of tumor response by combining131I- with gemcitabine (GEM), a cytotoxic radiosensitizer. Nude mice mammary fat-pad (MFP) tumors and BCBMs were generated with braintropic MDA-MB-231Br cells transduced with bicistronically-linked NIS and firefly luciferase cDNAs. Response was monitored in vivo via bioluminescent imaging and NIS tumor expression.131I-/GEM therapy inhibited MFP tumor growth more effectively than either agent alone. BCBMs were treated with: high or low-dose GEM (58 or 14.5 mg/Kg×4); 131I- (1mCi or 2×0.5 mCi 7 days apart); and 131I-/GEM therapy. By post-injection day (PID) 25, 82-86% of controls and 78-83% of 131I--treated BCBM grew, whereas 17% low-dose and 36% high-dose GEM regressed. The latter tumors were smaller than the controls with comparable NIS expression (~20% of cells). High and low-dose 131I-/ GEM combinations caused 89% and 57% tumor regression, respectively. High-dose GEM/131I- delayed tumor growth: tumors increased 5-fold in size by PID45 (controls by PID18). Although fewer than 25% of cells expressed NIS, GEM/131I- caused dramatic tumor regression in NIS-transduced BCBMs. This effect was synergistic, and supports the hypothesis that GEM radiosensitizes cells to 131I-.
View details for DOI 10.18632/oncotarget.10238
View details for Web of Science ID 000385435000059
Palliative Surgery for Advanced Cancer: Identifying Evidence-Based Criteria for Patient Selection: Case Report and Review of Literature
JOURNAL OF PALLIATIVE MEDICINE
2016; 19 (1): 22-29
Criteria for selecting patients with advanced cancer for palliative surgery (PS) remains poorly defined. Decision making for PS requires realistic treatment goals with well-defined criteria. Here we discuss a 71-year-old Jehovah's Witness with advanced stage renal cell carcinoma (RCC) who presented with profound anemia due to intractable bleeding from gastric metastasis. After repeated attempts with endoscopic and angiographic management, she underwent surgical palliation. Through this case, we developed 10-item evidence-based criteria for selecting patients for PS.The study objective was to provide a review of pertinent literature for PS and identify evidence-based criteria for patient selection. These criteria were relevant for selecting this patient with metastatic RCC and may prove beneficial for selecting advanced cancer patients for PS.A MEDLINE search revealed 175 publications relevant to PS. Among these, 17 articles defining patient selection criteria (PSC) were reviewed. A frequency-based analysis of each criterion was performed. Another search returned 30 cases of RCC gastric metastases from 25 published reports. Outcome analysis was determined by the Kaplan-Meier actuarial method.Ten criteria were identified: symptom control, prognosis, preoperative performance status, quality of life (QoL), tumor burden amenable to palliation, procedure-related morbidity and mortality, feasibility of nonsurgical therapies, anticipated hospitalization, requirement for additional palliation, and cost. This patient met all inclusion criteria and underwent a successful gastrectomy. Median survival for patients with RCC gastric metastasis was 20 months.This report illustrates an example of implementation of evidence-based criteria for selecting advanced cancer patients for PS. Validation of these criteria is warranted.
View details for DOI 10.1089/jpm.2015.0146
View details for Web of Science ID 000367057700007
View details for PubMedID 26565437
Pancreatic mucinous cystic neoplasm in a transgender patient
WORLD JOURNAL OF SURGICAL ONCOLOGY
Cystic pancreatic lesions are increasingly more frequent detected clinical entities. Mucinous cystic neoplasm (MCN) is a hormone-related pancreatic tumor (HRTP) with a strong predominance in young and middle-aged females.Here, we present the case of a 31-year-old surgically transgendered female-to-male patient with a history of alcoholic pancreatitis, on chronic testosterone therapy. He was found to have a pancreatic MCN and underwent distal pancreatectomy and splenectomy.To our knowledge, this is the first reported case of a transgender patient with a history of hormone replacement therapy (HRT) and pancreatic MCN. We consider possible mechanisms for the pathogenesis to explain this patient's neoplasm.
View details for DOI 10.1186/s12957-015-0620-8
View details for Web of Science ID 000357085900001
View details for PubMedID 26104783
View details for PubMedCentralID PMC4486435
Richter-type Spigelian hernia: A case report and review of the literature.
International journal of surgery case reports
2015; 6C: 160-162
Abdominal wall hernias through the arcuate line termed Spigelian hernias are uncommon. These hernias presenting as a Richter-type, with strangulation of part of the circumference of the bowel wall is very rare.We report a 27-year-old male patient who presented with a Richter-type Spigelian hernia.A MEDLINE literature search of this rare entity yielded six publications presenting Richter-type Spigelian hernias. All of these articles and accompanying references were thoroughly reviewed. There was no gender or anatomical side predominance among the patients. All except our patient presented here were elderly. Pain was the most common symptom and was present in all patients. All patients underwent surgical repair and none reported recurrence of their hernia afterwards.Richter-type Spigelian hernia is rare and has been reported infrequently in the existing literature. Clinical diagnosis is challenging and CT scan is the diagnostic study of choice. Surgical repair is the definitive treatment and involves primary or mesh repair of the defect as appropriate. Necrotic bowel should be resected and we recommend biologic mesh repair in these cases if the defect is large.
View details for DOI 10.1016/j.ijscr.2014.10.088
View details for PubMedID 25544481
View details for PubMedCentralID PMC4334998
Evaluation of three rapid diagnostic tests for the detection of human infections with Plasmodium knowlesi
Plasmodium knowlesi, a malaria parasite of Southeast Asian macaques, infects humans and can cause fatal malaria. It is difficult to diagnose by microscopy because of morphological similarity to Plasmodium malariae. Nested PCR assay is the most accurate method to distinguish P. knowlesi from other Plasmodium species but is not cost effective in resource-poor settings. Rapid diagnostic tests (RDTs) are recommended for settings where malaria is prevalent. In this study, the effectiveness of three RDTs in detecting P. knowlesi from fresh and frozen patient blood samples was evaluated.Forty malaria patients (28 P. knowlesi, ten P. vivax and two P. falciparum) diagnosed by microscopy were recruited in Sarawak, Malaysian Borneo during a 16-month period. Patient blood samples were used to determine parasitaemia by microscopy, confirm the Plasmodium species present by PCR and evaluate three RDTs: OptiMAL-IT, BinaxNOW® Malaria and Paramax-3. The RDTs were also evaluated using frozen blood samples from 41 knowlesi malaria patients.OptiMAL-IT was the most sensitive RDT, with a sensitivity of 71% (20/28; 95% CI = 54-88%) for fresh and 73% (30/41; 95% CI = 59-87%) for frozen knowlesi samples. However, it yielded predominantly falciparum-positive results due to cross-reactivity of the P. falciparum test reagent with P. knowlesi. BinaxNOW® Malaria correctly detected non-P. falciparum malaria in P. knowlesi samples but was the least sensitive, detecting only 29% (8/28; 95% CI = 12-46%) of fresh and 24% (10/41; 95% CI = 11-37%) of frozen samples. The Paramax-3 RDT tested positive for P. vivax with PCR-confirmed P. knowlesi samples with sensitivities of 40% (10/25; 95% CI = 21-59%) with fresh and 32% (13/41; 95% CI = 17-46%) with frozen samples. All RDTs correctly identified P. falciparum- and P. vivax-positive controls with parasitaemias above 2,000 parasites/μl blood.The RDTs detected Plasmodium in P. knowlesi-infected blood samples with poor sensitivity and specificity. Patients with P. knowlesi could be misdiagnosed as P. falciparum with OptiMAL-IT, P. vivax with Paramax-3 and more correctly as non-P. vivax/non-P. falciparum with BinaxNOW® Malaria. There is a need for a sensitive and specific RDT for malaria diagnosis in settings where P. knowlesi infections predominate.
View details for DOI 10.1186/1475-2875-13-60
View details for Web of Science ID 000332774300003
View details for PubMedID 24548805
View details for PubMedCentralID PMC3931291
Ex vivo Evans blue assessment of the blood brain barrier in three breast cancer brain metastasis models.
Breast cancer research and treatment
2014; 144 (1): 93-101
The limited entry of anticancer drugs into the central nervous system represents a special therapeutic challenge for patients with brain metastases and is primarily due to the blood brain barrier (BBB). Albumin-bound Evans blue (EB) dye is too large to cross the BBB but can grossly stain tissue blue when the BBB is disrupted. The course of tumor development and the integrity of the BBB were studied in three preclinical breast cancer brain metastasis (BCBM) models. A luciferase-transduced braintropic clone of MDA-231 cell line was used. Nude mice were subjected to stereotactic intracerebral inoculation, mammary fat pad-derived tumor fragment implantation, or carotid artery injections. EB was injected 30 min prior to euthanasia at various timepoints for each of the BCBM model animals. Serial bioluminescent imaging demonstrated exponential tumor growth in all models. Carotid BCBM appeared as diffuse multifocal cell clusters. EB aided the localization of metastases ex vivo. Tumor implants stained blue at 7 days whereas gross staining was not evident until day 14 in the stereotactic model and day 28 for the carotid model. EB assessment of the integrity of the BBB provides useful information relevant to drug testing in preclinical BCBM models.
View details for DOI 10.1007/s10549-014-2854-5
View details for PubMedID 24510011
View details for PubMedCentralID PMC4363122
Two treatments, one disease: childhood malaria management in Tanga, Tanzania
In the Tanga District of coastal Tanzania, malaria is one of the primary causes of mortality for children under the age of five. While some children are treated with malaria medications in biomedical facilities, as the World Health Organization recommends, others receive home-care or treatment from traditional healers. Recognition of malaria is difficult because symptoms can range from fever with uncomplicated malaria to convulsions with severe malaria. This study explores why caregivers in the Tanga District of Tanzania pursue particular courses of action to deal with malaria in their children.Qualitative data were collected through interviews with three samples: female caregivers of children under five (N = 61), medical practitioners (N = 28), and traditional healers (N = 18) in urban, peri-urban, and rural areas. The female caregiver sample is intentionally stratified to reflect the greater population of the Tanga District in level of education, marital status, gender of household head, religion, and tribal group affiliation. Qualitative data were counted, coded and analysed using NVivo7 software.Results indicate that a variety of factors influence treatment choice, including socio-cultural beliefs about malaria symptoms, associations with spiritual affliction requiring traditional healing, knowledge of malaria, and fear of certain anti-malaria treatment procedures. Most notably, some caregivers identified convulsions as a spiritual condition, unrelated to malaria. While nearly all caregivers reported attending biomedical facilities to treat children with fever (N = 60/61), many caregivers stated that convulsions are best treated by traditional healers (N = 26/61). Qualitative interviews with medical practitioners and traditional healers confirmed this belief.Results offer insight into current trends in malaria management and have implications in healthcare policy, educational campaigns, and the importance of integrating traditional and biomedical approaches.
View details for DOI 10.1186/1475-2875-8-240
View details for Web of Science ID 000272254600001
View details for PubMedID 19860900
View details for PubMedCentralID PMC2779815