Nitric oxide synthase immunoreactivity of interstitial cells of Cajal in experimental colitis

OBJECTIVE: There is functional and morphological evidence that interstitial cells of Cajal (ICC) may play a role in nitric oxide (NO) dependent signal transduction. However, little is known about the nitric oxide synthase (NOS) containing ICC during inflammation. MATERIALS AND METHODS: Immunocytochemical methods were used for the ultrastructural localization of NOS1-containing ICC in the wall of the colon of rats in experimental colitis. RESULTS: Large numbers of NOS immunoreactive (IR) nerve terminals were found in very close vicinity to smooth muscle cells as well as to blood vessels. IR nerves were found in close relationship with the ICC. The gap between the NOS IR nerve fibers and the membrane of smooth muscle cells and of ICC was 20-250 nm. In experimental colitis the number of NOS IR nerve fibers slightly decreased, however, large numbers (24%) of the ICC became IR for NOS. In the noninflamed area and in the controls, all these cells were immunonegative for NOS. CONCLUSIONS: Our light- and ultrastructural study suggests that some of the ICC can also synthesize NO, at least during inflammation. Therefore the change in the number and structure of ICC could play an important role in the pathogenesis of a variety of motility disorders.     

Risk correlates of prevalent HIV,hepatitis B virus,and hepatitis C virus infections among noninjecting heroin users

OBJECTIVE: To examine lifetime correlates of HIV and hepatitis B and C (HBV and HCV) infections among noninjecting heroin users (NIUs). METHODS: Between March 1996 and March 2001, 483 eligible NIUs were tested for HIV, HBV, and HCV antibodies and administered structured interviews. Multivariate logistic regression analyses were stratified by injecting history. RESULTS: Among never-injectors (69.8%), significant (p <.05) correlates were unprotected sex with men who have sex with men (HIV and HBV), unprotected sex with NIUs (HIV), self-reported syphilis infection (HBV), longer duration of heroin use (HBV and HCV), shorter duration of cocaine use (HIV), blood transfusion before 1986 (HIV), and having been tattooed (HCV). Among former injectors (30.2%), significant correlates were receptive syringe sharing (HIV and HBV), frequent lifetime injection (HCV), longer duration of sexual activity (HBV), and having been tattooed (HCV). CONCLUSION: Never-injectors infected with HIV and HBV appear to have become infected mainly through sexual transmission, whereas former injectors appear to have become infected with HIV and HCV mainly though injecting risk and with HBV through both injecting and sexual risk. Interventions targeted at NIUs should prevent unsafe sex as well as the initiation or resumption of injecting. In addition, unhygienic tattooing, which may lead to HCV exposure, should be a focus of prevention efforts.     

Computational fluid dynamics modeling of impeller designs for the HeartQuest left ventricular assist device

To finalize the design of the next generation of the HeartQuest left ventricular assist device, a suitable impeller had to be designed and tested. The new prototype was based on calculations and test results of previous designs, but required several changes to decrease the size. For most pump designs, this is a simple matter of altering impeller geometry and rotational speed to achieve the desired pressure rise and flow rate. However, this particular pump was limited by housing geometry and the magnetic bearings that support the impeller. Without much freedom in the overall impeller size, the only parameters open to the designers were the blade profiles and the rotating speed. Rather than build several candidates and test them in a rig at enormous cost, computational models of several designs were tested and analyzed. This not only saved money, but also sped up the development time for the project. The computer models were developed in TASCflow, a computational fluid dynamics software package from AEA Technologies. This paper analyzes the data from several of the selected models, paying close attention to pumping performance and general trends from specific design changes.     

Phenotypic characterization of regulatory CD4+CD25+ T cells in rats

CD25 has become widely used as a marker for a subset of regulatory CD4(+) T cells present in the thymus and periphery of mice, rats and humans. However, CD25 is also expressed on conventionally activated T cells that are not regulatory and not all peripheral regulatory T cells express CD25. The identification of a stable and unique marker for regulatory T cells would therefore be valuable. This study provides a detailed account of the phenotype of CD4(+)CD25(+) regulatory T cells in rats. In the thymus, CD4(+)CD8(-)CD25(+) cells were found to have a more mature phenotype than the corresponding CD4(+)CD8(-)CD25(-) cells with respect to expression of Thy1 (CD90), CD53 and CD44, suggesting that CD25 expression, and perhaps commitment to regulatory function, might be a late event in thymocyte development. CD4(+)CD25(+) cells in both the thymus and periphery were found to have enriched and heterogeneous expression of activation markers such as OX40 (CD134) and OX48 (an antibody determined in this study to be specific for CD86). CD4(+)CD25(+) T cells were also found to have enriched expression of CD80, at both the mRNA and protein level. However, functional studies in vitro and in vivo showed that neither OX40 or CD86 were useful markers for the further subdivision of regulatory T cells. Our studies indicate that, at present, CD25 remains the most useful marker to enrich for regulatory CD4(+) T cells in rats and no further subdivision of the regulatory component of CD4(+)CD25(-)CD45RC(low) T cells has yet been achieved.     

Thymocyte-thymocyte interaction for efficient positive selection and maturation of CD4 T cells

Despite numerous reports on MHC class II expression by T cells from a wide spectrum of mammalian species including humans, the biological relevance of this phenomenon has never been tested with appropriately designed animal models. To address this issue, we developed mouse models in which immature thymocytes are the only positively selecting antigen-presenting cells in the thymus. In these mice, CD4+ T cells were generated with the appropriate maturation phenotype and showed a diverse repertoire of TCR Vbetas. The CD4+ T cells were functionally competent, mediating effective allogeneic responses that involved polyclonal TCR Vbetas. These results suggest that the thymocyte-thymocyte (T-T) interaction operates as an independent pathway for CD4+ T cell selection in the thymi of species with MHC II-positive thymocytes. This T-T interaction appears to be the basis for the generation of donor MHC-restricted CD4+ T cells in xenogeneic hosts.     

Predominant type 1 CMV-specific memory T-helper response in humans: evidence for gender differences in cytokine secretion

Cell-mediated memory immune responses to viral antigens are important for protection against viruses causing persistent or acute infections. This study compared the cytokine profile of memory T-helper cells specific for cytomegalovirus (CMV) in healthy CMV-seropositive men and women. The cytokine response reflected T(H)1 bias, with dominant secretion of interferon (IFN)-gamma along with moderate levels of tumor necrosis factor-alpha, interleukin (IL)-10, and IL-2. Analyzed by gender, women had higher and significant spontaneous release of IFN-gamma and CMV-specific IL-2 secretion. Similar analysis with herpes simplex virus-1 showed a trend toward higher cytokine responsiveness in women, but the differences were not statistically significant. In contrast, men had statistically significant higher influenza virus-specific tumor necrosis factor-alpha secretion. IL-4 and IL-5, both T(H)2 cytokines, were low for all three viruses. The results show a predominant T(H)1 antiviral cytokine T-help memory response with significant differences linked to gender. Such differences may have an impact in the design of immunization strategies against CMV.