Thomas J. Erichsen

Gilbert's Syndrome and Irinotecan Toxicity: Combination with UDP-Glucuronosyltransferase 1A7 Variants Increases Risk

Background: Gilberts syndrome is characterized by a functional promoter single nucleotide polymorphism (SNP) of the UDP-glucuronosyltransferase (UGT) 1A1 gene and represents a pharmacogenetic risk factor for irinotecan toxicity, but study data remain controversial. The active CPT-11 metabolite 7-ethyl-10-hydroxycamptothecin is detoxified by several UGT1A proteins, which include UGT1A7 with a high specific activity that may contribute to the risk of irinotecan toxicity in Gilberts syndrome patients. Methods: Genotyping of the UGT1A1*28, UGT1A7 N129K/R131K, and UGT1A7-57T/G variants was done in 105 irinotecan-treated patients with metastatic colorectal cancer; adverse events were documented during all 297 treatment cycles and analyzed by Cochran-Mantel-Haenszel, Mann-Whitney, and χ2 tests. Results: The presence of UGT1A7 but not UGT1A1 variants was associated with at least one adverse event. In patients combining all three variants, thrombocytopenia and leukopenia were significantly more frequent. The overall incidence of adverse events was significantly higher (P = 0.0035) in carriers of the UGT1A risk alleles, who also had significantly higher rate of dose reductions. Conclusions: Irinotecan toxicity is more likely in patients with Gilberts syndrome carrying the UGT1A1*28 allele combined with reduced function UGT1A7 N129K/R131K and UGT1A7-57T/G SNP. Based on the ability of UGT1A7 to metabolize and eliminate the active irinotecan metabolite 7-ethyl-10-hydroxycamptothecin, the UGT1A1/UGT1A7 SNP combination haplotype appears to be a superior risk predictor than Gilberts syndrome alone. (Cancer Epidemiol Biomarkers Prev 2008;17(3):695–701)

Inactivation and Survival of Hepatitis C Virus on Inanimate Surfaces

BACKGROUND Hepatitis C virus (HCV) cross-contamination from inanimate surfaces or objects has been implicated in transmission of HCV in health-care settings and among injection drug users. We established HCV-based carrier and drug transmission assays that simulate practical conditions to study inactivation and survival of HCV on inanimate surfaces. METHODS Studies were performed with authentic cell culture derived viruses. HCV was dried on steel discs and biocides were tested for their virucidal efficacy against HCV. Infectivity was determined by a limiting dilution assay. HCV stability was analyzed in a carrier assay for several days or in a drug transmission assay using a spoon as cooker. RESULTS HCV can be dried and recovered efficiently in the carrier assay. The most effective alcohol to inactivate the virus was 1-propanol, and commercially available disinfectants reduced infectivity of HCV to undetectable levels. Viral infectivity on inanimate surfaces was detectable in the presence of serum for up to 5 days, and temperatures of about 65-70°C were required to eliminate infectivity in the drug transmission assay. CONCLUSIONS These findings are important for assessment of HCV transmission risks and should facilitate the definition of stringent public health interventions to prevent HCV infections.

Genetic variability of aryl hydrocarbon receptor (AhR)-mediated regulation of the human UDP glucuronosyltransferase (UGT) 1A4 gene

UDP glucuronosyltransferases (UGTs) play an important role for drug detoxification and toxicity. UGT function is genetically modulated by single nucleotide polymorphisms (SNPs) which lead to the expression of functionally altered protein, or altered expression levels. UGT1A4 activity includes anticonvulsants, antidepressants and environmental mutagens. In this study the induction of the human UGT1A4 gene and a potential influence of genetic variation in its promoter region were analyzed. SNPs at bp -219 and -163 occurred in 9% among 109 blood donors reducing UGT1A4 transcription by 40%. UGT1A4 transcription was dioxin inducible. Reporter gene experiments identified 2 xenobiotic response elements (XRE), which were functionally confirmed by mutagenesis analyses, and binding was demonstrated by electromobility shift assays. Constitutive human UGT1A4 gene expression and induction was aryl hydrocarbon receptor (AhR)-dependent, and reduced in the presence of SNPs at bp -219 and -163. AhR-mediated regulation of the human UGT1A4 gene by two XRE and a modulation by naturally occurring genetic variability by SNPs is demonstrated, which indicates gene-environment interaction with potential relevance for drug metabolism.

Aryl hydrocarbon receptor-mediated regulation of the human estrogen and bile acid UDP-glucuronosyltransferase 1A3 gene

UDP-glucuronosyltransferases contribute to the detoxification of drugs by forming water soluble β-d-glucopyranosiduronic acids. The human UGT1A3 protein catalyzes the glucuronidation of estrogens, bile acids and xenobiotics including non-steroidal anti-inflammatory drugs and lipid lowering drugs. Regulation of UGT1A3 by xenobiotic response elements is likely, but the responsible elements are yet uncharacterized. In addition, genetic promoter variants may affect UGT1A3 regulation and potential induction by xenobiotics. The UGT1A3 promoter was analyzed by mutagenesis, reporter gene, and mobility shift analyses. Three hundred and eighty-nine blood donors were genotyped for promoter single nucleotide polymorphisms (SNPs) showing an allelic frequency of 42% of variants at −66 (T to C) and −204 (A to G). A xenobiotic response element regulating aryl hydrocarbon receptor (AhR)-mediated UGT1A3 transcription was identified and characterized. UGT1A3 transcription was reduced in the presence of promoter SNPs. These data demonstrate xenobiotic induced regulation of the UGT1A3 gene by the AhR, which shows genetic variability.

Successful treatment of cervical esophageal leakage by endoscopic-vacuum assisted closure therapy

AIM To evaluate the efficacy and safety of endoscopic-vacuum assisted closure (E-VAC) therapy in the treatment of cervical esophageal leakage. METHODS Between May and November 2012, three male patients who developed post-operative cervical esophageal leakage were treated with E-VAC therapy. One patient had undergone surgical excision of a pharyngo-cervical liposarcoma with partial esophageal resection, and the other two patients had received surgical treatment for symptomatic Zenkers diverticulum. Following endoscopic verification of the leakage, a trimmed polyurethane sponge was fixed to the distal end of a nasogastric silicone tube and endoscopically positioned into the wound cavity, and with decreasing cavity size the sponge was positioned intraluminally to cover the leak. Continuous suction was applied, and the vacuum drainage system was changed twice a week. RESULTS The initial E-VAC placement was technically successful for all three patients, and complete closure of the esophageal leak was achieved without any procedure-related complications. In all three patients, the insufficiencies were located either above or slightly below the upper esophageal sphincter. The median duration of the E-VAC drainage was 29 d (range: 19-49 d), with a median of seven sponge exchanges (range: 5-12 sponge exchanges). In addition, the E-VAC therapy reduced inflammatory markers to within normal range for all three patients. Two of the patients were immediately fitted with a percutaneous enteral gastric feeding tube with jejunal extension, and the third patient received parenteral feeding. All three patients showed normal swallow function and no evidence of stricture after completion of the E-VAC therapy. CONCLUSION E-VAC therapy for cervical esophageal leakage was well tolerated by patients. This safe and effective procedure may significantly reduce morbidity and mortality following cervical esophageal leakage.

Microbiological Analysis of Fluids in Postsurgical Gastroesophageal Intrathoracic Leaks Obtained by Endoscopy: A New Way to Optimize Antibiotic Therapy

Background/Aims: Postsurgical gastroesophageal intrathoracic leakage is a potentially life-threatening condition that is frequently accompanied by mediastinitis and subsequent sepsis. Aspiration of fluids from intrathoracic leaks during endoscopy for microbiological analysis is rarely performed in clinical routine. The aim was to evaluate the role of routine microbiological analysis of intrathoracic leaks via endoscopy and its impact on antibiotic therapy. Methods: This is a prospective, observational single-center study. Seventeen consecutive patients who presented for endoscopic treatment of intrathoracic leaks were included. Concomitantly, fluids from intrathoracic leaks during endoscopic intervention and blood cultures were obtained and a microbiological analysis was performed. Results: Bacteria and/or fungi were detected by culture of fluid aspirated from intrathoracic leaks in 88% cases, but in none of the blood cultures. In 15 patients, microbial colonization of the leakage was detected despite previous empiric antibiotic therapy; treatment had to be adjusted in all patients according to the observed antibiotic susceptibility profile. Conclusions: The microbiological colonization of postsurgical gastroesophageal intrathoracic leaks in patients is frequent. Only the direct microbiological analysis of fluids from intrathoracic leaks, but not of blood cultures, is effective for optimizing an antibiotic therapy in such patients.