Research Spotlight

Posted June 15th 2016

Urine colorimetry to detect Low rifampin exposure during tuberculosis therapy: a proof-of-concept study.

Tawanda Gumbo M.D.

Tawanda Gumbo M.D.

Zentner, I., H. P. Schlecht, L. Khensouvann, N. Tamuhla, M. Kutzler, V. Ivaturi, J. G. Pasipanodya, T. Gumbo, C. A. Peloquin, G. P. Bisson and C. Vinnard (2016). “Urine colorimetry to detect low rifampin exposure during tuberculosis therapy: A proof-of-concept study.” BMC Infect Dis 16(1): 242.

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BACKGROUND: The cost and complexity of current approaches to therapeutic drug monitoring during tuberculosis (TB) therapy limits widespread use in areas of greatest need. We sought to determine whether urine colorimetry could have a novel application as a form of therapeutic drug monitoring during anti-TB therapy. METHODS: Among healthy volunteers, we evaluated 3 dose sizes of rifampin (150 mg, 300 mg, and 600 mg), performed intensive pharmacokinetic sampling, and collected a timed urine void at 4 h post-dosing. The absorbance peak at 475 nm was measured after rifamycin extraction. The optimal cutoff was evaluated in a study of 39 HIV/TB patients undergoing TB treatment in Botswana. RESULTS: In the derivation study, a urine colorimetric assay value of 4.0 x 10(-2) Abs, using a timed void 4 h after dosing, demonstrated a sensitivity of 92 % and specificity of 60 % to detect a peak rifampin concentration (Cmax) under 8 mg/L, with an area under the ROC curve of 0.92. In the validation study, this cutoff was specific (100 %) but insensitive (28 %). We observed similar test characteristics for a target Cmax target of 6.6 mg/L, and a target area under the drug concentration-versus-time curve (AUC0-8) target of 24.1 mg*hour/L. CONCLUSIONS: The urine colorimetric assay was specific but insensitive to detect low rifampin serum concentrations among HIV/TB patients. In future work we will attempt to optimize sampling times and assay performance, with the goal of delivering a method that can translate into a point-of-care assessment of rifampin exposure during anti-TB therapy.


Posted June 15th 2016

Functional specialty of cd40 and dendritic cell surface lectins for exogenous antigen presentation to cd8(+) and cd4(+) t cells.

SangKon Oh Ph.D.

SangKon Oh Ph.D.

Yin, W., L. Gorvel, S. Zurawski, D. Li, L. Ni, D. Duluc, K. Upchurch, J. Kim, C. Gu, R. Ouedraogo, Z. Wang, Y. Xue, H. Joo, J. P. Gorvel, G. Zurawski and S. Oh (2016). “Functional specialty of cd40 and dendritic cell surface lectins for exogenous antigen presentation to cd8(+) and cd4(+) t cells.” EBioMedicine 5: 46-58.

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Dendritic cells (DCs) are major antigen-presenting cells that can efficiently prime and cross-prime antigen-specific T cells. Delivering antigen to DCs via surface receptors is thus an appealing strategy to evoke cellular immunity. Nonetheless, which DC surface receptor to target to yield the optimal CD8(+) and CD4(+) T cell responses remains elusive. Herein, we report the superiority of CD40 over 9 different lectins and scavenger receptors at evoking antigen-specific CD8(+) T cell responses. However, lectins (e.g., LOX-1 and Dectin-1) were more efficient than CD40 at eliciting CD4(+) T cell responses. Common and distinct patterns of subcellular and intracellular localization of receptor-bound alphaCD40, alphaLOX-1 and alphaDectin-1 further support their functional specialization at enhancing antigen presentation to either CD8(+) or CD4(+) T cells. Lastly, we demonstrate that antigen targeting to CD40 can evoke potent antigen-specific CD8(+) T cell responses in human CD40 transgenic mice. This study provides fundamental information for the rational design of vaccines against cancers and viral infections.


Posted June 15th 2016

Whole exome sequencing in patients with white matter abnormalities.

Raphael Schiffmann M.D.

Raphael Schiffmann M.D.

Vanderver, A., C. Simons, G. Helman, J. Crawford, N. I. Wolf, G. Bernard, A. Pizzino, J. L. Schmidt, A. Takanohashi, D. Miller, A. Khouzam, V. Rajan, E. Ramos, S. Chowdhury, T. Hambuch, K. Ru, G. J. Baillie, S. M. Grimmond, L. Caldovic, J. Devaney, M. Bloom, S. H. Evans, J. L. Murphy, N. McNeill, B. L. Fogel, R. Schiffmann, M. S. van der Knaap and R. J. Taft (2016). “Whole exome sequencing in patients with white matter abnormalities.” Ann Neurol 79(6): 1031-1037.

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Here we report whole exome sequencing (WES) on a cohort of 71 patients with persistently unresolved white matter abnormalities with a suspected diagnosis of leukodystrophy or genetic leukoencephalopathy. WES analyses were performed on trio, or greater, family groups. Diagnostic pathogenic variants were identified in 35% (25 of 71) of patients. Potentially pathogenic variants were identified in clinically relevant genes in a further 7% (5 of 71) of cases, giving a total yield of clinical diagnoses in 42% of individuals. These findings provide evidence that WES can substantially decrease the number of unresolved white matter cases.


Posted June 15th 2016

A long-term co-perfused disseminated tuberculosis-3d liver hollow fiber model for both drug efficacy and hepatotoxicity in babies.

Tawanda Gumbo M.D.

Tawanda Gumbo M.D.

Srivastava, S., J. G. Pasipanodya, G. Ramachandran, D. Deshpande, S. Shuford, H. E. Crosswell, K. N. Cirrincione, C. M. Sherman, S. Swaminathan and T. Gumbo (2016). “A long-term co-perfused disseminated tuberculosis-3d liver hollow fiber model for both drug efficacy and hepatotoxicity in babies.” EBioMedicine 6: 126-138.

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Treatment of disseminated tuberculosis in children/=6years has not been optimized. The pyrazinamide-containing combination regimen used to treat disseminated tuberculosis in babies and toddlers was extrapolated from adult pulmonary tuberculosis. Due to hepatotoxicity worries, there are no dose-response studies in children. We designed a hollow fiber system model of disseminated intracellular tuberculosis with co-perfused three-dimensional organotypic liver modules to simultaneously test for efficacy and toxicity. We utilized pediatric pharmacokinetics of pyrazinamide and acetaminophen to determine dose-dependent pyrazinamide efficacy and hepatotoxicity. Acetaminophen concentrations that cause hepatotoxicity in children led to elevated liver function tests, while 100mg/kg pyrazinamide did not. Surprisingly, pyrazinamide did not kill intracellular Mycobacterium tuberculosis up to fourfold the standard dose as monotherapy or as combination therapy, despite achieving high intracellular concentrations. Host-pathogen RNA-sequencing revealed lack of a pyrazinamide exposure transcript signature in intracellular bacteria or of phagolysosome acidification on pH imaging. Artificial intelligence algorithms confirmed that pyrazinamide was not predictive of good clinical outcomes in children


Posted June 15th 2016

The use of endoluminal vacuum (e-vac) therapy in the management of upper gastrointestinal leaks and perforations.

James W. Fleshman M.D.

James W. Fleshman M.D.

Smallwood, N. R., J. W. Fleshman, S. G. Leeds and J. S. Burdick (2016). “The use of endoluminal vacuum (e-vac) therapy in the management of upper gastrointestinal leaks and perforations.” Surg Endosc 30(6): 2473-2480.

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INTRODUCTION: Upper intestinal leaks and perforations are associated with high morbidity and mortality rates. Despite the growing experience using endoscopically placed stents, the treatment of these leaks and perforations remain a challenge. Endoluminal vacuum (E-Vac) therapy is a novel treatment that has been successfully used in Germany to treat upper gastrointestinal leaks and perforations. There currently are no reports on its use in the USA. METHODS: E-Vac therapy was used to treat 11 patients with upper gastrointestinal leaks and perforations from September 2013 to September 2014. Five patients with leaks following sleeve gastrectomy were excluded from this study. A total of six patients were treated with E-Vac therapy; these included: (n = 2) iatrogenic esophageal perforations, (n = 1) iatrogenic esophageal and gastric perforations, (n = 1) iatrogenic gastric perforation, (n = 1) gastric staple line leak following a surgical repair of a traumatic gastric perforation, and (n = 1) esophageal perforation due to an invasive fungal infection. Four patients had failed an initial surgical repair prior to starting E-Vac therapy. RESULTS: All six patients (100 %) had complete closure of their perforation or leak after an average of 35.8 days of E-Vac therapy requiring 7.2 different E-Vac changes. No deaths occurred in the 30 days following E-Vac therapy. One patient died following complete closure of his perforation and transfer to an acute care facility due to an unrelated complication. There were no complications directly related to the use of E-Vac therapy. Only one patient had any symptoms of dysphagia. This patient had severe dysphagia from an esophagogastric anastomotic stricture prior to her iatrogenic perforations. Following E-Vac therapy, her dysphagia had actually improved and she could now tolerate a soft diet. CONCLUSIONS: E-Vac therapy is a promising new method in the treatment of upper gastrointestinal leaks and perforations. Current successes need to be validated through future prospective controlled studies.