Search

Individuals with end-stage renal disease (ESRD) are 10- to 25-fold more likely than immunocompetent people to develop active tuberculosis (TB) and are candidates for being treated for latent TB infection (LTBI). However, diagnosis using the tuberculin skin test (TST) is doubly difficult due to cutaneous anergy and cross-reactions with Bacille–Calmette–Guérin (BCG) vaccination. This was a prospective, doublematched, cohort study in which 32 ESRD patients and 32 age-matched, healthy controls were enrolled. The TST and two new interferon-γ blood tests, QuantiFERON-TB Gold (QFT-G) and T-SPOT.TB (ELISPOT), were performed. The subjects were followed up 2 years for active TB disease. ELISPOT was done in ESRD patients only. Compared to the healthy controls, a high prevalence of LTBI was found in the ESRD patients by TST (62.5%, 95% confidence interval [CI] 43.7–78.9), QFT-G (40.0%, 95% CI 22.7–59.4), and ELISPOT (46.9%, 95% CI 29.1–65.3). Agreement was moderate (kappa [κ] = 0.53) for QFT-G and ELISPOT but only slight between TST and QFT-G (κ = 0.25) and fair between TST and ELISPOT (κ = 0.32). ESRD (p = 0.03) and diabetes mellitus (p = 0.04) were significant risk factors for QFT-G positivity on the multivariable analysis. The overall rate of active TB was 1.66 cases per 100 person-years (pys), with the rate higher in patients with ESRD (3.53 per 100 pys) and those with positive (3.40 per 100 pys) and indeterminate QFT results (30.16 per 100 pys), although the difference was not statistically significant. Sensitivity, specificity, and positive and negative predictive values of QFT-G for active TB was 100%, 62.1%, 8.3% and 100%. This pilot study is the first to compare QFT-G, ELISPOT, and TST in ESRD patients on hemodialysis and demonstrates a high prevalence of LTBI in this population. In our study, the QFT-G was the more accurate method for identifying those truly infected with Mycobacterium tuberculosis, even in BCG-vaccinated individuals. [ABSTRACT FROM AUTHOR]

Abstract Background and Aims: The expression of hepatitis B viral (HBV) antigens in liver tissue reflects the replicative status of chronic HBV infection. We have previously recognized a novel marginal pattern of hepatitis B surface antigen (HBsAg) in hepatocytes, which usually clusters in groups and emerges at the late non-replicative phase. This study was designed to investigate whether the marginal-type HBsAg represented the gene product of a specific HBV-surface mutant. Methods: Microdissection of cirrhotic nodules homogeneously expressing marginal HBsAg was performed on two of 12 resected livers from HBsAg-seropositive patients with hepatocellular carcinoma. The gene presumably encoding marginal HBsAg was polymerase chain reaction (PCR)-cloned, sequenced and analysed. In vitro transfection and expression of the cloned surface mutant plasmids were performed on the Huh7 cell line to illustrate intrahepatic HBsAg expression. Results: Immunohistochemical staining revealed that the marginal HBsAg was positive for pre-S1 and thus contained large surface proteins. The PCR cloning and sequencing of the genes presumably encoding marginal-type HBsAg in both cases revealed the same deletion at the 5′ terminus (nt 2–55) of pre-S2. A point mutation on the small-surface (S) antigen was also found in one case. The pre-S2 deletion sequence and the mutation sites of the S gene coincide with human lymphocyte antigen-restricted T- and/or B-cell epitopes. In vitro transfection of the mutant plasmid revealed a blot-like retention or accumulation of HBsAg in the cytoplasm or at the periphery of hepatocytes, accompanied by a decreased secretion of HBsAg in the culture supernatant, mimicking intrahepatic expression. Conclusion: A natural pre-S2 deletion mutant was identified in hepatocytes expressing a novel marginal pattern of HBsAg, which probably contains mutant, large, surface proteins. The biological significance of the pre-S2 deletion mutant should be interesting in view of the clustering proliferation of hepatocytes expressing marginal HBsAg. [ABSTRACT FROM AUTHOR]

We aimed to develop an H. pylori-infected mouse model using clinically stored strains in Taiwan and to test whether development of H. pylori infection in an in vivo animal model is related to the status of the cagA gene. A total of 100 male BALB/c mice, 6-8 weeks old, including 80 in the experimental group and 20 in the control group, were used. Two clinically stored H. pylori isolates, a cagA-positive and a cagA-negative strain, were selected to induce the H. pylori infection in half (N = 40) of the mice in the experimental group. Bacterial isolates of 0.8 x 10(9) CFU/ml were orally inoculated in each mouse of the experimental group for three consecutive days. Ten mice in the control group were sacrificed to confirm the initial absence of H. pylori. Eight weeks after inoculation of the experimental group and no inoculation of the remaining 10 mice of the control group, each mouse was killed. Gastrectomy was then performed for rapid urease test (CLOtest) and histology. In the control group, none of 20 mice had positive results from the CLOtest or histology. In contrast, excluding eight of 80 mice that died before the eighth week, 90.3% (65/72) of the mice challenged with H. pylori showed persistent presence of H. pylori by histology. The severity of gastritis at the eighth week was more evident in H. pylori-infected mice than in control and noninfected mice (P < 0.05). Although gastritis was more severe in mice inoculated with the cagA-positive strain than with the cagA-negative strain, the rates of H. pylori infection in mice were not different between cagA-positive and -negative strains (91.4% vs 89.2%, P > 0.05). In summary, stored strains of H. pylori can be applied to induce an infection model in BALB/c mice. The less virulent cagA-negative strain can induce H. pylori infection in mice as effectively as the cagA-positive strain. The high prevalence of cagA-positive strains in Taiwanese patients may be related to factors other than only the cagA gene of the bacteria. [ABSTRACT FROM AUTHOR]

The class I tyrosine kinase growth-factor receptors include epidermal growth factor receptor (EGFR), ErbB2 (c-erbB-2, HER-2/neu), ErbB3 and ErbB4. To elucidate their role in the regulation of homeostasis and carcinogenesis, we examined the expression of the receptors in normal urothelium and in urothelial carcinoma by immunohistochemistry. EGFR was expressed in the basal cells of normal urothelium, while ErbB2, ErbB3 and ErbB4 were present mainly in the superficial layer. A distinct reciprocal distribution was observed between the EGFR and the remaining members of the subclass (P = 0.0001). Both BCL-2 protein and Ki-67 antigen (MIB-1) showed a strong positive association with EGFR (P = 0.002) and an inverse correlation with ErbB2, ErbB3 or ErbB4 (P = 0.0004, 0.0000, and 0.001, respectively). With regard to carcinoma, there was no important relationship between receptor overexpression and tumour grading (P > 0.1), while only EGFR overexpression was correlated with muscular invasion (P = 0.02). Coexpression of EGFR-ErbB3 and ErbB3-ErbB4 was more often detected in high-grade tumours and correlated with the extent of tumour invasion. Our data indicate that class I receptors are differentially expressed in normal urothelium in vivo, but an orchestrated expression pattern does not exist during tumorigenesis. [ABSTRACT FROM AUTHOR]