Sublethal effects of methylmercury on fecal metabolites of testosterone, estradiol, and corticosterone in captive juvenile white ibises (Eudocimus albus).

Methylmercury (MeHg) is a globally distributed neurotoxin, endocrine disruptor, and teratogen, and its effects on birds are poorly understood, especially within an environmentally relevant exposure range. In an effort to understand the potential causal relationship between MeHg exposure and endocrine development, we established four dietary exposure groups (0 [control], 0.05, 0.1, and 0.3 mg/kg wet wt/d of MeHg) of postfledging white ibises (Eudocimus albus) in a divided, free-flight aviary that spanned the estimated range of environmental exposure for this species. Fecal samples were collected from individually identified ibises over six months in 2005 and processed for hormone evaluation. Significant sex-related differences in fecal estradiol concentrations, though unpredicted in direction, suggest that this steroid could be related to juvenile development in this species. Using repeated-measures general linear models, we tested a set of candidate models to explain variation in endocrine expression. We found that MeHg exposure led to significant differences in fecal estradiol concentrations between the control and medium-dose groups, whereas differences in fecal corticosterone concentrations were observed between the control and both the low- and high-dose groups. These results suggest highly nonlinear dose-response patterns for MeHg. Many endocrine-disrupting contaminants are theorized to affect multiple endpoints in a nonlinear manner, making results difficult to interpret using a traditional toxicological approach. The evidence presented here suggests that endocrine effects of MeHg exposure could behave similarly.

Prognostic significance of the hepatitis B virus-DNA concentration in patients after orthotopic liver transplantation.

Hepatitis B virus-DNA was detected by polymerase chain reaction in 9 out of 10 patients after orthotopic liver transplantation. Three of these patients were at the same time positive for hepatitis B virus-DNA by dot-blot hybridization (hepatitis B virus-DNA > 1.5 pg/ml). In these three patients HBs-antigen (HBsAg) reappeared within a mean time of 12 weeks after orthotopic liver transplantation (range 7-18 weeks). Only two of the six polymerase chain reaction-positive and dot-blot-negative patients (hepatitis B virus-DNA between 0.4 fg/ml and 1.5 pg/ml) had recurrence of HBsAg within a mean time of 54 weeks (range 52-56 weeks). Passive immunoprophylaxis with anti-HBs antibodies (serum titers > 100 IU/l) did not prevent infection of the graft in the five reinfected patients. We conclude that a low concentration of serum hepatitis B virus-DNA after orthotopic liver transplantation, which is detectable only by polymerase chain reaction, indicates a delayed infection of the graft.

Isolation of Chlamydia trachomatis from the lower digestive tract.

Chlamydia trachomatis was isolated from ten of 188 biopsies (5.3%) obtained from different parts of the lower digestive tract. Patients (mean age 37.0 years) presented with ulcerative proctitis, Crohn's disease, mild colitis or ulcerative colitis. Seven rectal biopsies, two biopsies from the sigmoid flexure and one caecal biopsy were positive for chlamydial isolation whereas all biopsies taken from the colon ascendens, transversum or descendens and from the terminal ileum were negative. We conclude that isolation of C. trachomatis is most effective from rectal and sigmoidal biopsies and is a rare event from other sites of the lower digestive tract.

Close correlation between hepatitis C virus serology and polymerase chain reaction in chronically infected patients.

To determine whether the persistent presence of antibodies to recombinant antigens of the hepatitis C virus (HCV) corresponds to the presence of hepatitis C virus RNA in the same serum, 85 anti-HCV positive patients were studied by the polymerase chain reaction (PCR). The focus of the research was on patients with chronic hepatitis. Eighty- three patients were found to be positive by PCR; only two were negative. In addition, liver biopsies taken from seven patients positive for anti-HCV were shown to contain HCV-specific RNA. Sera collected from three patients suspected to have NANB hepatitis on the basis of clinical symptoms were negative both for HCV antibodies and HCV RNA. The correlation between HCV antibody positivity and detection of HCV RNA was 97.6%.