Biomedical subjects

Michael Torbenson

Publications and source records attributed to Michael Torbenson.

42 records · Page 3Linked to original sources

PubMed2002

Severity and correlates of liver disease in hepatitis C virus-infected injection drug users.

Between May 1996 and June 1998, 210 members of a cohort of 1,667 hepatitis C virus (HCV)-infected injection drug users (IDUs) were selected for liver biopsy procedure after stratification based on 2 consecutive serum alanine transaminase (ALT) levels. Liver histology, which could be fully evaluated for 207 subjects, was classified by using the modified Ishak scores. At the time of biopsy, the median age of subjects was 41.3 years and the median estimated duration of HCV infection was 20.7 years; 94% were African American; 78% men; 31% were human immunodeficiency virus (HIV) seropositive; and 76% had HCV genotype 1a or 1b. Total modified histologic activity index (MHAI) scores ranged from 0 to 9, and 26.6% had a total MHAI score of 5 or greater. Persons with a total MHAI score of 5 or greater were more likely to be HIV infected (P =.04). Higher fibrosis, indicated by Ishak modified fibrosis scores of 3 to 6, was present in 10.1% of subjects and was found more often in those older than 46 years of age (the highest quartile) (P <.01). Both fibrosis scores of 3 or greater and total scores of 5 or greater were associated with elevated ALT, aspartate transaminase (AST), and gamma-glutamyl transpeptidase (GGT) levels (P <.01). When serial values were considered, the results of liver enzyme testing could reduce the probability of an IDU having a fibrosis score of 3 or greater from 10% to 3%. In conclusion, these data indicate that severe liver disease is uncommon in this urban, HCV-infected IDU cohort, especially in younger persons and those with repeatedly normal liver enzymes.

Adult↗

PubMed2002

Sporadic fundic gland polyposis: a clinical, histological, and molecular analysis.

Sporadic fundic gland polyposis (SFGP) is defined as multiple fundic gland polyps in patients without familial adenomatous polyposis syndrome (FAP). Although little is known about the genetic changes in SFGP, mutations in the Wnt signaling pathway have been recently linked to fundic gland polyps in other settings: sporadic polyps are linked to activating beta-catenin mutations, whereas FAP-associated fundic gland polyps are caused by second somatic hits in the adenomatous polyposis coli gene. The relationship between SFGP, single sporadic fundic gland polyps, and FAP-associated polyps remains unclear, and SFGP remain poorly characterized at the clinical, histological, and molecular levels. A retrospective study was undertaken of eight patients with SFGP who had >/=10 polyps with at least five endoscopic biopsy specimens available for study. One additional patient with attenuated FAP who underwent partial gastrectomy was included as a control. The medical records and biopsy specimens were reviewed. Mutations of the beta-catenin gene were evaluated in each fundic gland as well as in control nonpolypoid tissue by direct sequencing of a mutational hot spot in exon 3 of the beta-catenin gene, which encodes the GSK-3beta phosphorylation sites, and a HinfI endonuclease digestion assay. The four men and four women in the study were an average of 57 years of age at biopsy. All patients were on acid-suppression therapy, 5/8 with proton-pump inhibitors (PPI) and 3/8 with Zantac. Sixty-two polyps were studied, and all were <10 mm, with most between 2 and 7 mm. The polyps were histologically identical to single sporadic fundic gland polyps. No dysplasia was seen. Forty-seven of 62 polyps (76%) had detectable beta-catenin mutations. Mutations were found in all eight of the patients. All were point mutations in codons 32, 33, 34, and 37 and are either phosphorylation sites or immediately adjacent to phosphorylation sites, findings identical to that seen in single sporadic fundic gland polyps. Each polyp had a single mutation, and each patient had more than one unique mutation (median = 4), indicating a multifocal origin for the polyps. No mutations were found in nonpolypoid control tissue and in polyps from the attenuated FAP patient. The patients with SFGP in this series were all between 40 and 70 years of age and had histories of acid-suppressive therapy. The fundic gland polyps were histologically and genetically identical to single sporadic fundic gland polyps and demonstrated frequent somatic activating mutations in exon 3 of the beta-catenin gene.

Adenomatous Polyposis Coli↗

PubMed2002

Hepatocellular carcinomas show abnormal expression of fibronectin protein.

Fibronectin plays an important role in cell-to-cell adhesion, cell migration, and cell signaling. In the liver, fibronectin expression has been studied primarily as a component of the extracellular matrix, but little information is available on the expression of fibronectin protein in the neoplastic cells of hepatocellular carcinomas (HCCs). Twenty-four surgically resected HCCs were immunostained with fibronectin. Tumor and normal liver tissues were concurrently analyzed in all cases, and expression in the tumor was evaluated in comparison to the nonneoplastic liver. The average age at resection was 54 +/- 18 years for the 18 men and 6 women. Twenty-one of the cases were classic HCCs including 6 cases that were well differentiated, 12 cases moderately differentiated, and 3 cases poorly differentiated. The remaining 3 cases were moderately differentiated fibrolamellar carcinomas. In the normal liver, fibronectin labeled the sinusoids and weakly to moderately stained the cytoplasm of hepatocytes. In HCCs, 15/24 showed overexpression of fibronectin in the cytoplasm, 8/24 showed no change from the nonneoplastic liver, and one case showed decreased cytoplasmic staining. In addition, an abnormal membranous staining pattern was noted in 16/24 HCCs. In contrast to the HCCs, none of the three fibrolamellar carcinomas showed increased cytoplasmic or membranous staining. Excluding fibrolamellar carcinoma, increased cytoplasmic staining and/or an abnormal membranous staining was noted in 19/21 (90%) of HCCs. Fibronectin shows abnormal cytoplasmic and/or membranous staining in the majority of HCCs. The implications of fibronectin overexpression are uncertain but may reflect a critical step in tumor genesis.

Adult↗

PubMed2002

Colchicine effect in a colonic hyperplastic polyp. A lesion mimicking serrated adenoma.

Colchicine effect has been described recently in gastrointestinal biopsies, where it can result in accumulation of metaphase mitoses and epithelial disorganization. We describe the case of a colonic hyperplastic polyp with colchicine effect from a 52-year-old woman who was receiving colchicine for primary biliary cirrhosis. Biopsy of the polyp revealed prominent metaphase mitoses and focal loss of nuclear polarity in the surface epithelium, features that mimicked a serrated adenoma. Distinguishing between hyperplastic polyp and serrated adenoma is important because of the different management implications and the increased potential for neoplastic progression in the latter.

Adenoma↗

PubMedDate not supplied

Race and comorbid factors predict nonalcoholic fatty liver disease histopathology in severely obese patients.

PURPOSE: Nonalcoholic fatty liver disease (NAFLD) is a common and potentially serious form of chronic liver disease. Although NAFLD is known to be associated with obesity and some comorbid conditions, less is known about the severity of NAFLD among different racial groups. METHODS: We prospectively studied 237 consecutive morbidly obese patients presenting for bariatric surgery. All patients underwent intraoperative liver biopsy and chart review. After excluding subjects who reported alcohol use (n = 37) or who had missing biopsy data (n = 11), 189 patients were available for analysis. Clinical and laboratory associations with each of the histological components of NAFLD were assessed using multiple logistic regression analysis. RESULTS: The mean age was 43.1 years, 84% were female, and 13% were African American. It was found that 88% had steatosis, including 35% with moderate to severe steatosis (> 33% of hepatocytes involved). Of these patients, 67% had inflammation, 46% had fibrosis, and 45% met Brunt's criteria for NASH. Compared with Caucasians and after adjustment, African Americans had significantly lower odds of severe hepatic pathology, with adjusted odds ratios of 0.1 (P = .02) for the presence of moderate or severe steatosis, 0.2 for inflammation (P = .006), 0.3 for fibrosis (P = .05), and 0.2 for NASH (P = .02). In addition, participants with one or more features of the metabolic syndrome (ie, diabetes, hypertension, or dyslipidemia) or elevated aminotransferase levels had significantly higher odds of severe hepatic histopathology. CONCLUSION: Among obese patients presenting for bariatric surgery, NAFLD is more common in Caucasians, patients with features of the metabolic syndrome, and those with elevated aminotransferase levels.

Adult↗

PubMedDate not supplied

Expression of inducible nitric oxide synthase in paired neoplastic and non-neoplastic primary prostate cell cultures and prostatectomy specimen.

Nitric oxide (NO) is an important signaling molecule for ischemia, inflammation, angiogenesis, immune response, and cell growth and differentiation. It has recently been shown that increased production of NO within various human cancers may contribute to tumor angiogenesis, tumor growth and metastasis, and tumor-related immune suppression. NO can be produced by several NO synthases (NOS), including inducible synthase (iNOS), which is expressed during cell activation and produces NO in larger quantity and for a longer period of time than non-inducible NOSs. In this study, we examined the expression levels of iNOS mRNA and protein in prostate adenocarcinoma using a paired nonneoplastic and neoplastic primary prostate cell culture system and related prostatectomy specimens. Six pairs of neoplastic and nonneoplastic primary prostate cell cultures were established from radical prostatectomy specimens based on homogeneity of the originating tumor and the nonneoplastic tissue. Radioactive reverse transcriptase polymerase chain reaction and subsequent quantitative analysis of iNOS mRNA were performed on the cultures using beta-actin as an internal control. Immunohistochemical studies with an anti-iNOS monoclonal antibody were performed on the corresponding formalin-fixed paraffin-embedded prostatectomy tissue sections. We observed marked patient-to-patient variation in "normal" levels of iNOS mRNA. However, all six neoplastic cultures showed moderately to markedly higher mRNA levels than did their paired nonneoplastic cultures. In addition, iNOS protein levels were significantly higher in paraffin-embedded prostate cancer tissue sections than in adjacent nonneoplastic tissue. Overexpression of iNOS mRNA and protein levels is present in moderately differentiated prostate adenocarcinoma and may contribute to prostate cancer angiogenesis, tumor growth, and tumor-related immunosuppression.

Adenocarcinoma↗