Research Spotlight

Gottlieb, R. L., T. Sam, S. Y. Wada, J. F. Trotter, S. K. Asrani, B. Lima, S. M. Joseph, G. Gonzalez-Stawinski and S. A. Hall (2017). “Rational heart transplant from hepatitis c donor: New antiviral weapons conquer the trojan.” J Card Fail: 2017 Aug [Epub ahead of print].

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BACKGROUND: Donors with hepatitis C (HCV) viremia are rarely utilized for orthotopic heart transplantation (OHTx) due to post-transplant risks. New, highly effective HCV antivirals may alter the landscape. METHODS: An adult patient unsuitable for bridging mechanical support therapy accepted a heart transplant offer from a donor with HCV viremia. Upon daily logarithmic rise in HCV viral load and adequate titers to ensure successful genotyping, once daily sofosbuvir 400 mg / velpatasvir 100 mg (Epclusa) was initiated empirically pending HCV genotype (genotype 3a confirmed after initiation of therapy). RESULTS: We report the kinetics of acute Hepatitis C viremia and therapeutic response to treatment with a new pangenotypic antiviral agent after donor-derived acute HCV infection transmitted incidental to successful cardiac transplant into a HCV negative OHTx recipient. Prompt resolution of viremia was noted by the first week of a 12 week course of antiviral therapy. Sustained virologic remission continues beyond 12 weeks after completion of HCV therapy (SVR-12). CONCLUSIONS: The availability of effective pangenotypic therapy for HCV may expand donor availability. The feasibility of early versus late treatment of HCV remains to be determined through formalized protocols. We hypothesize pharmacoeconomics to be the greatest limitation to widespread availability of this promising tool.

Graham, J. P., P. Authie, A. Karolina Palucka and G. Zurawski (2017). “Targeting interferon-alpha to dendritic cells enhances a cd8+ t cell response to a human cd40-targeted cancer vaccine.” Vaccine 35(35 Pt B): 4532-4539.

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Targeting antigens to antigen presenting cells (APC) enhances the potency of recombinant protein CD8+ T cell vaccines. Recent comparisons of recombinant protein-based dendritic cell (DC) targeting vaccines revealed differences in cross-presentation and identified CD40 as a potent human DC receptor target for antigen cross-presentation. Contrary to in vitro-derived monocyte (mo)DC, we found that interferon-alpha (IFNalpha) stimulation of human blood-derived DC was necessary for an antigen-specific IFNgamma CD8+ T cell response to a CD40 targeted cancer vaccine. Importantly, targeting an adjuvant in the form of IFNalpha to DC increased their potency to elicit antigen-specific production of IFNgamma by CD8+ T cells. Thus, we introduce the concept of DC adjuvant targeting to enhance the potency of vaccination.

Gupta, S., J. J. Gao, M. Emmett and A. Z. Fenves (2017). “Topiramate and metabolic acidosis: An evolving story.” Hosp Pract (1995): 1-4.

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Topiramate is an anticonvulsant that is being increasingly used for a number of different off-label indications. Its inhibition of carbonic anhydrase isoenzymes can lead to metabolic acidosis, elevated urine pH, reduced urine citrate, and hypercalciuria, thereby creating a milieu that is ripe for calcium phosphate stone formation. In this review, we describe a case of topiramate-induced metabolic acidosis. We review the frequency of metabolic acidosis among children and adults, as well as the mechanism of hyperchloremic metabolic acidosis and renal tubular acidosis in topiramate users. Finally, we describe the long-term effects of topiramate-induced metabolic acidosis, including nephrolithiasis, nephrocalcinosis, and bone degradation. Patients who are prescribed topiramate should be carefully monitored for metabolic derangements, and they may benefit from alkali supplementation, or in extreme cases, discontinuation of the drug altogether.

Kay, J., D. de Sa, L. Morrison, E. Fejtek, N. Simunovic, H. D. Martin and O. R. Ayeni (2017). “Surgical management of deep gluteal syndrome causing sciatic nerve entrapment: A systematic review.” Arthroscopy: 2017 Aug [Epub ahead of print].

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PURPOSE: To assess the causes, surgical indications, patient-reported clinical outcomes, and complications in patients with deep gluteal syndrome causing sciatic nerve entrapment. METHODS: Three databases (PubMed, Ovid [MEDLINE], and Embase) were searched by 2 reviewers independently from database inception until September 7, 2016. The inclusion criteria were studies reporting on both arthroscopic and open surgery and those with Level I to IV evidence. Systematic reviews, conference abstracts, book chapters, and technical reports with no outcome data were excluded. The methodologic quality of the studies was assessed with the MINORS (Methodological Index for Non-randomized Studies) tool. RESULTS: The search identified 1,539 studies, of which 28 (481 patients; mean age, 48 years) were included for assessment. Of the studies, 24 were graded as Level IV, 3 as Level III, and 1 as Level II. The most commonly identified causes were iatrogenic (30%), piriformis syndrome (26%), trauma (15%), and non-piriformis (hamstring, obturator internus) muscle pathology (14%). The decision to pursue surgical management was made based on clinical findings and diagnostic investigations alone in 50% of studies, whereas surgical release was attempted only after failed conservative management in the other 50%. Outcomes were positive, with an improvement in pain at final follow-up (mean, 23 months) reported in all 28 studies. The incidence of complications from these procedures was low: Fewer than 1% and 8% of open surgical procedures and 0% and fewer than 1% of endoscopic procedures resulted in major (deep wound infection) and minor complications, respectively. CONCLUSIONS: Although most of the studies identified were case series and reports, the results consistently showed improvement in pain and a low incidence of complications, particularly for endoscopic procedures. These findings lend credence to surgical management as a viable option for buttock pain caused by deep gluteal syndrome and warrant further investigation.

Lee, L., J. Kelly, G. J. Nassif, D. Keller, T. C. Debeche-Adams, P. A. Mancuso, J. R. Monson, M. R. Albert and S. B. Atallah (2017). “Establishing the learning curve of transanal minimally invasive surgery for local excision of rectal neoplasms.” Surg Endosc: 2017 Aug [Epub ahead of print].

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INTRODUCTION: Transanal minimally invasive surgery (TAMIS) is an endoscopic operating platform for local excision of rectal neoplasms. However, it may be technically demanding, and its learning curve has yet to be adequately defined. The objective of this study was to determine the number of TAMIS procedures for the local excision of rectal neoplasm required to reach proficiency. METHODS AND PROCEDURES: All TAMIS cases performed from 07/2009 to 12/2016 at a single high-volume tertiary care institution for local excision of benign and malignant rectal neoplasia were identified from a prospective database. A cumulative summation (CUSUM) analysis was performed to determine the number of cases required to reach proficiency. The main proficiency outcome was rate of margin positivity (R1 resection). The acceptable and unacceptable R1 rates were defined as the R1 rate of transanal endoscopic microsurgery (TEM-10%) and traditional transanal excision (TAE-26%), which was obtained from previously published meta-analyses. Comparisons of patient, tumor, and operative characteristics before and after TAMIS proficiency were performed. RESULTS: A total of 254 TAMIS procedures were included in this study. The overall R1 resection rate was 7%. The indication for TAMIS was malignancy in 57%. CUSUM analysis reported that TAMIS reached an acceptable R1 rate between 14 and 24 cases. Moving average plots also showed that the mean operative times stabilized by proficiency gain. The mean lesion size was larger after proficiency gain (3.0 cm (SD 1.5) vs. 2.3 cm (SD 1.3), p = 0.008). All other patient, tumor, and operative characteristics were similar before and after proficiency gain. CONCLUSIONS: TAMIS for local excision of rectal neoplasms is a complex procedure that requires a minimum of 14-24 cases to reach an acceptable R1 resection rate and lower operative duration.