Clinical Assistant Professor, Anesthesiology, Perioperative and Pain Medicine
Board Certification: American Board of Anesthesiology, Anesthesia (2021)
Fellowship: Stanford University Anesthesiology Fellowships (2020) CA
Residency: Stanford University Anesthesiology Residency (2019) CA
Internship: Alameda County Highland Hospital Internal Medicine Residency (2016) CA
Medical Education: Tufts University School of Medicine (2015) MA
M.D., Tufts University School of Medicine, Medicine (2015)
Ph.D, University of Cambridge, Immunology (2014)
MPH, Tufts University School of Medicine, Public Health (2015)
The effects of sildenafil on ciliary beat frequency in patients with pulmonary non-tuberculous mycobacteria disease: phase I/II trial.
BMJ open respiratory research
2020; 7 (1)
RATIONALE: Pulmonary non-tuberculous mycobacterial (PNTM) disease has increased over the past several decades, especially in older women. Abnormal mucociliary clearance and abnormal nasal nitric oxide (nNO) have been associated with PNTM disease in other patient cohorts. Mucociliary clearance can be affected by NO-cyclic guanosine monophosphate signalling and, therefore, modulation of the pathway may be possible with phosphodiesterase inhibitors such as sildenafil as a novel therapeutic approach.OBJECTIVE: To define ex vivo characteristics of PNTM disease affected by sildenafil.METHODS: Subjects with PNTM infections were recruited into an open-label dose-escalation trial of sildenafil. Laboratory measurements and mucociliary measurements-ciliary beat frequency, nNO and 24-hour sputum production-were collected throughout the study period. Patients received sildenafil daily during the study period, with escalation from 20 to 40 mg three times per day.MEASUREMENTS AND MAIN RESULTS: Increased ciliary beat frequency occurred after a single dose of 40mg sildenafil and after extended dosing of 40mg sildenafil. The increase ciliary beat frequency was not seen with 20mg sildenafil dosing. There were no changes in sputum production, nNO production, Quality of Life-Bronchiectasis-NTM module (QOL-B-NTM) questionnaire or the St George's Respiratory Questionnaire during the study period.CONCLUSION: Sildenafil, 40mg, increased ciliary beat frequency acutely as well as with extended administration.
View details for DOI 10.1136/bmjresp-2020-000574
View details for PubMedID 32169832
Feasibility study of a smartphone pupillometer and evaluation of its accuracy.
Journal of clinical monitoring and computing
Measurement of pupillary characteristics, such as pupillary unrest in ambient light, and reflex dilation have been shown to be useful in a variety of clinical situations. Dedicated pupillometers typically capture images in the near-infrared to allow imaging in both light and darkness. However, because a subset of pupillary measurements can be acquired with levels of visible light suitable for conventional cameras, it is theoretically possible to capture data using general purpose cameras and computing devices such as those found on smartphones. Here we describe the development of a smartphone-based pupillometer and compare its performance with a commercial pupillometer. Smartphone pupillometry software was developed and then compared with a commercial pupillometer by performing simultaneous scans in both eyes, using the smartphone pupillometer and a commercial pupillometer. The raw scans were compared, as well as a selected pupillary index: pupillary unrest in ambient light. In 77% of the scans the software was able to successfully identify the pupil and iris. The raw data as well as calculated values of pupillary unrest in ambient light were in clinically acceptable levels of agreement; Bland-Altman analysis of raw pupil measurements yielded a 95% confidence interval of 0.26 mm. In certain situations a smartphone pupillometer may be an appropriate alternative to a commercial pupillometer.
View details for DOI 10.1007/s10877-020-00592-x
View details for PubMedID 32951188
- Performance of Litholyme compared with Sodasorb carbon dioxide absorbents in a standard clinical setting. British journal of anaesthesia 2019; 122 (1): e11–e12
TNF overproduction impairs epithelial staphylococcal response in hyper IgE syndrome.
The Journal of clinical investigation
2018; 128 (8): 3595-3604
Autosomal dominant hyper IgE syndrome (AD-HIES), or Job's syndrome, is a primary immune deficiency caused by dominant-negative mutations in STAT3. Recurrent Staphylococcus aureus skin abscesses are a defining feature of this syndrome. A widely held hypothesis that defects in peripheral Th17 differentiation confer this susceptibility has never been directly evaluated. To assess the cutaneous immune response in AD-HIES, we induced suction blisters in healthy volunteers (HVs) and patients with AD-HIES and then challenged the wound with lethally irradiated bacteria. We show that cutaneous production of IL-17A and IL-17F was normal in patients with AD-HIES. Overproduction of TNF-α differentiated the responses in AD-HIES from HVs. This was associated with reduced IL-10 family signaling in blister-infiltrating cells and defective epithelial cell function. Mouse models of AD-HIES recapitulated these aberrant epithelial responses to S. aureus and involved defective epithelial-to-mesenchymal transition (EMT) rather than a failure of bacterial killing. Defective responses in mouse models of AD-HIES and primary keratinocyte cultures from patients with AD-HIES could be reversed by TNF-α blockade and by drugs with reported modulatory effects on EMT. Our results identify these as potential therapeutic approaches in patients with AD-HIES suffering S. aureus infections.
View details for DOI 10.1172/JCI121486
View details for PubMedID 30035749
View details for PubMedCentralID PMC6063472
Assessing the Collective Dynamics of Motile Cilia in Cultures of Human Airway Cells by Multiscale DDM
2017; 113 (1): 109–19
The technique of differential dynamic microscopy is extended here, showing that it can provide a powerful and objective method of video analysis for optical microscopy videos of in vitro samples of live human bronchial epithelial ciliated cells. These cells are multiciliated, with motile cilia that play key physiological roles. It is shown that the ciliary beat frequency can be recovered to match conventional analysis, but in a fully automated fashion. Furthermore, it is shown that the properties of spatial and temporal coherence of cilia beat can be recovered and distinguished, and that if a collective traveling wave (the metachronal wave) is present, this has a distinct signature and its wavelength and direction can be measured.
View details for DOI 10.1016/j.bpj.2017.05.028
View details for Web of Science ID 000405646900014
View details for PubMedID 28700909
View details for PubMedCentralID PMC5510766
Closed-Loop Anesthesia: Wave of the Future or No Future?
You’re Wrong, I’m Right.
Springer International Publishing Switzerland. 2017; 1: 19–20
View details for DOI 10.1007/978-3-319-43169-7_5
Pulmonary Nontuberculous Mycobacterial Infection A Multisystem, Multigenic Disease
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
2015; 192 (5): 618–28
The clinical features of patients infected with pulmonary nontuberculous mycobacteria (PNTM) are well described, but the genetic components of infection susceptibility are not.To examine genetic variants in patients with PNTM, their unaffected family members, and a control group.Whole-exome sequencing was done on 69 white patients with PNTM and 18 of their white unaffected family members. We performed a candidate gene analysis using immune, cystic fibrosis transmembrance conductance regulator (CFTR), cilia, and connective tissue gene sets. The numbers of patients, family members, and control subjects with variants in each category were compared, as was the average number of variants per person.A significantly higher number of patients with PNTM than the other subjects had low-frequency, protein-affecting variants in immune, CFTR, cilia, and connective tissue categories (35, 26, 90, and 90%, respectively). Patients with PNTM also had significantly more cilia and connective tissue variants per person than did control subjects (2.47 and 2.55 compared with 1.38 and 1.40, respectively; P = 1.4 × 10(-6) and P = 2.7 × 10(-8), respectively). Patients with PNTM had an average of 5.26 variants across all categories (1.98 in control subjects; P = 2.8 × 10(-17)), and they were more likely than control subjects to have variants in multiple categories. We observed similar results for family members without PNTM infection, with the exception of the immune category.Patients with PNTM have more low-frequency, protein-affecting variants in immune, CFTR, cilia, and connective tissue genes than their unaffected family members and control subjects. We propose that PNTM infection is a multigenic disease in which combinations of variants across gene categories, plus environmental exposures, increase susceptibility to the infection.
View details for DOI 10.1164/rccm.201502-0387OC
View details for Web of Science ID 000361344500015
View details for PubMedID 26038974
View details for PubMedCentralID PMC4595692
- A Familial Syndrome of Pulmonary Nontuberculous Mycobacteria Infections AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE 2013; 188 (11): 1373–76
Abnormal Nasal Nitric Oxide Production, Ciliary Beat Frequency, and Toll-like Receptor Response in Pulmonary Nontuberculous Mycobacterial Disease Epithelium
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
2013; 187 (12): 1374–81
Pulmonary nontuberculous mycobacterial (PNTM) disease has increased over the past several decades, especially in older women. Despite extensive investigation, no consistent immunological abnormalities have been found. Using evidence from diseases such as cystic fibrosis and primary ciliary dyskinesia, in which mucociliary dysfunction predisposes subjects to high rates of nontuberculous mycobacterial disease that increase with age, we investigated correlates of mucociliary function in subjects with PNTM infections and healthy control subjects.To define ex vivo characteristics of PNTM disease.From 2009 to 2012, 58 subjects with PNTM infections and 40 control subjects were recruited. Nasal nitric oxide (nNO) was determined at the time of respiratory epithelial collection. Ciliary beat frequency at rest and in response to Toll-like receptor (TLR) and other agonists was determined using high-speed video microscopy.We found decreased nNO production, abnormally low resting ciliary beat frequency, and abnormal responses to agonists of TLR2, -3, -5, -7/8, and -9 in subjects with PNTM compared with healthy control subjects. The low ciliary beat frequency in subjects with PNTM was normalized ex vivo by augmentation of the NO-cyclic guanosine monophosphate pathway without normalization of their TLR agonist responses.Impaired nNO, ciliary beat frequency, and TLR responses in PNTM disease epithelium identify possible underlying susceptibility mechanisms as well as possible avenues for directed investigation and therapy.
View details for DOI 10.1164/rccm.201212-2197OC
View details for Web of Science ID 000320362600017
View details for PubMedID 23593951
View details for PubMedCentralID PMC3734613
Clinical experience with a simple algorithm for plerixafor utilization in autologous stem cell mobilization
BONE MARROW TRANSPLANTATION
2012; 47 (12): 1526–29
Plerixafor augments PBSC collection, but the optimal approach for incorporating it into mobilization is uncertain. Forty-nine consecutive patients mobilized with G-CSF alone were analyzed, and a day 4 peripheral blood CD34(+) cell count of 0.015/ml was found to predict for a day 5 apheresis yield of 2 × 10(6) CD34(+) progenitors/kg, our institutional minimum necessary for a single autologous transplant. On the basis of this relationship, a clinical guideline was developed which recommended pre-emptive use of plerixafor if the day 4 peripheral blood CD34(+) cell count was between 0.005 and 0.015/ml. A total of 166 consecutive subjects with lymphoma or plasma cell dyscrasias underwent G-CSF mobilization after adoption of this care pathway, and the mobilization failure rate was only 7% in patients managed per guideline. The median PBSC yield was 6.3 × 10(6) CD34(+) progenitors/kg with G-CSF (day 4 peripheral blood CD34(+) cell > 0.015/ml) and 4.9 × 10(6) CD34(+) progenitors/kg with G-CSF+plerixafor (day 4 peripheral blood CD34(+) cell 0.005-0.015/ml). The median number of days of apheresis was 2 in both groups. This clinical guideline is an effective mobilization algorithm that minimizes mobilization failures, reduces poor apheresis yields, does not require risk factor identification and is simple to implement.
View details for DOI 10.1038/bmt.2012.74
View details for Web of Science ID 000312082600006
View details for PubMedID 22562080
Preserving immunogenicity of lethally irradiated viral and bacterial vaccine epitopes using a radio- protective Mn2+-Peptide complex from Deinococcus.
Cell host & microbe
2012; 12 (1): 117-124
Although pathogen inactivation by γ-radiation is an attractive approach for whole-organism vaccine development, radiation doses required to ensure sterility also destroy immunogenic protein epitopes needed to mount protective immune responses. We demonstrate the use of a reconstituted manganous peptide complex from the radiation-resistant bacterium Deinococcus radiodurans to protect protein epitopes from radiation-induced damage and uncouple it from genome damage and organism killing. The Mn(2+) complex preserved antigenic structures in aqueous preparations of bacteriophage lambda, Venezuelan equine encephalitis virus, and Staphylococcus aureus during supralethal irradiation (25-40 kGy). An irradiated vaccine elicited both antibody and Th17 responses, and induced B and T cell-dependent protection against methicillin-resistant S. aureus (MRSA) in mice. Structural integrity of viruses and bacteria are shown to be preserved at radiation doses far above those which abolish infectivity. This approach could expedite vaccine production for emerging and established pathogens for which no protective vaccines exist.
View details for DOI 10.1016/j.chom.2012.05.011
View details for PubMedID 22817993
View details for PubMedCentralID PMC4073300
Gene Therapy of Canine Leukocyte Adhesion Deficiency Using Lentiviral Vectors With Human CD11b and CD18 Promoters Driving Canine CD18 Expression
2011; 19 (1): 113–21
To identify cellular promoters in a self-inactivating (SIN) lentiviral vector that might be beneficial in treating children with leukocyte adhesion deficiency type 1 (LAD-1), we tested lentiviral vectors with human CD11 and CD18 leukocyte integrin proximal promoter elements directing expression of canine CD18 in animals with canine LAD (CLAD). Lentiviral vectors with either the human CD11b (637 bp) proximal promoter or the human CD18 (1,060 bp) proximal promoter resulted in the highest percentages of CD18(+) CLAD CD34(+) cells in vitro. Subsequently, two CLAD dogs were infused with autologous CD34(+) cells transduced with the hCD11b (637 bp)-cCD18 vector, and two CLAD dogs were infused with autologous CD34(+) cells transduced with the hCD18 (1,060 bp)-cCD18 vector. Each dog received a nonmyeloablative dose of 200 cGy total body irradiation (TBI) before the infusion of transduced cells. The two CLAD dogs treated with the hCD18 (1,060 bp)-cCD18 vector, and one of the two dogs treated with the hCD11b (637 bp)-cCD18 vector, had reversal of the CLAD phenotype. These studies using endogenous leukocyte integrin proximal promoters represent an important step in the development of gene therapy for children with LAD-1.
View details for DOI 10.1038/mt.2010.203
View details for Web of Science ID 000285869200015
View details for PubMedID 20859258
View details for PubMedCentralID PMC3017439
Life-threatening adenovirus infections in the setting of the immunocompromised allogeneic stem cell transplant patients.
Advances in hematology
2010; 2010: 601548
A single institution case series of adenovirus infections after allogeneic hematopoietic stem cell transplantation is presented to highlight the consideration for adenovirus infections as an etiology in patients with rapid hepatic or other sudden organ deterioration in the setting of apparent GVHD stabilization. The series also highlights that survival is limited with these infections often due in part to concomitant opportunistic infections. In addition, the pathophysiological events, such as GVHD and hepatic dysfunction, may complicate the clinical picture and delay therapy of an opportunistic infection. This is particularly true for adenoviral infections as they also have a distinct clinical picture in immunocompromised patients when compared to immune competent patients. Adenovirus infections also have the additional challenge that its treatment, cidofovir, has associated toxicities that can delay its administration. Recent developments has yielded an assay that can be used in the early detection and for serial determinations of adenovirus in patients with advanced GVHD, as well as a new therapeutic agent currently undergoing clinical trials.
View details for DOI 10.1155/2010/601548
View details for PubMedID 20672048
View details for PubMedCentralID PMC2904444
Clinical use of plerixafor in combination with granulocyte-colony stimulating factor in hematopoietic stem cell transplantation
TRANSPLANT RESEARCH AND RISK MANAGEMENT
2010; 2: 47–58
View details for Web of Science ID 000219098600007
Rescue from failed growth factor and/or chemotherapy HSC mobilization with G-CSF and plerixafor (AMD3100): an institutional experience
BONE MARROW TRANSPLANTATION
2009; 43 (12): 909–17
Auto-SCT has been shown to be a potentially curative treatment for a variety of hematological malignancies. Auto-SCT is dependent on the successful mobilization and collection of hematopoietic stem cells to ensure engraftment. The inability to mobilize sufficient number of hematopoietic stem cells using standard cytokine-assisted mobilization strategies excludes eligible patients from potentially curative auto-SCT. Plerixafor (AMD3100; Mozobil), a novel bicyclam antagonist of the SDF-1alpha/CXCR4 complex, has been reported previously to augment PBSC mobilization in patients undergoing their first planned stem cell mobilization and collection attempt. In our experience, 17 of 20 patients otherwise eligible for auto-SCT who failed previous mobilization attempts had successful mobilization of CD34(+) hematopoietic stem cells with one apheresis procedure, and an additional patient required two aphereses procedures, when treated with the combination of plerixafor and G-CSF on a compassionate use protocol available at our institution.
View details for DOI 10.1038/bmt.2008.409
View details for Web of Science ID 000267363000002
View details for PubMedID 19182831
Functional role of lipid raft microdomains in cyclic nucleotide-gated channel activation
2004; 65 (3): 503–11
Cyclic nucleotide-gated (CNG) channels are the primary targets of light- and odorant-induced signaling in photoreceptors and olfactory sensory neurons. Compartmentalized cyclic nucleotide signaling is necessary to ensure rapid and efficient activation of these nonselective cation channels. However, relatively little is known about the subcellular localization of CNG channels or the mechanisms of their membrane partitioning. Lipid raft domains are specialized membrane microdomains rich in cholesterol and sphingolipids that have been implicated in the organization of many membrane-associated signaling pathways. Herein, we report that the alpha subunit of the olfactory CNG channel, CNGA2, associates with lipid rafts in heterologous expression systems and in rat olfactory epithelium. However, CNGA2 does not directly bind caveolin, and its membrane localization overlaps only slightly with that of caveolin at the surface of human embryonic kidney (HEK) 293 cells. To test for a possible functional role of lipid raft association, we treated HEK 293 cells with the cholesterol-depleting agent, methyl-beta-cyclodextrin. Cholesterol depletion abolished prostaglandin E1-stimulated CNGA2 channel activity in intact cells. Recordings from membrane patches excised from CNGA2-expressing HEK 293 cells revealed that cholesterol depletion dramatically reduced the apparent affinity of homomeric CNGA2 channels for cAMP but only slightly reduced the maximal current. Our results show that olfactory CNG channels target to lipid rafts and that disruption of lipid raft microdomains dramatically alters the function of CNGA2 channels.
View details for DOI 10.1124/mol.65.3.503
View details for Web of Science ID 000189077700005
View details for PubMedID 14978228
Endoplasmic reticulum stress is a determinant of retrovirus-induced spongiform neurodegeneration
JOURNAL OF VIROLOGY
2003; 77 (23): 12617–29
FrCas(E) is a mouse retrovirus that causes a fatal noninflammatory spongiform neurodegenerative disease with pathological features strikingly similar to those induced by transmissible spongiform encephalopathy (TSE) agents. Neurovirulence is determined by the sequence of the viral envelope protein, though the specific role of this protein in disease pathogenesis is not known. In the present study, we compared host gene expression in the brain stems of mice infected with either FrCas(E) or the avirulent virus F43, differing from FrCas(E) in the sequence of the envelope gene. Four of the 12 disease-specific transcripts up-regulated during the preclinical period represent responses linked to the accumulation of unfolded proteins in the endoplasmic reticulum (ER). Among these genes was CHOP/GADD153, which is induced in response to conditions that perturb endoplasmic reticulum function. In vitro studies with NIH 3T3 cells revealed up-regulation of CHOP as well as BiP, calreticulin, and Grp58/ERp57 in cells infected with FrCas(E) but not with F43. Immunoblot analysis of infected NIH 3T3 cells demonstrated the accumulation of uncleaved envelope precursor protein in FrCas(E)- but not F43-infected cells, consistent with ER retention. These results suggest that retrovirus-induced spongiform neurodegeneration represents a protein-folding disease and thus may provide a useful tool for exploring the causal link between protein misfolding and the cytopathology that it causes.
View details for DOI 10.1128/JVI.77.23.12617-12629.2003
View details for Web of Science ID 000186612700023
View details for PubMedID 14610184
View details for PubMedCentralID PMC262586