Regulation of L-carnitine metabolism in Escherichia coli

The metabolization of L-carnitine was studied using whole cells of Escherichia coli 044 K74. It showed features of an epigenetical control. L-carnitine and crotonobetaine were able to induce the carnitine-reducing system. Oxygen and nitrate as electron acceptors, gamma-butyrobetaine as final product of carnitine transformation in E. coli as well as glucose repress the carnitine metabolization. Other betaines and structurally related compounds did not show any effect neither as inductors nor as repressors.     

Comparison between electrophysiologic and morphologic changes in lead induced peripheral neuropathy in rats

Compound nerve action potential (CNAP) of the mixed peripheral nerve is composed of A alpha beta, A delta, and C potentials. All components of CNAPs in the sciatic nerve were recorded by stimulating the tibial nerve of both control and lead-poisoned rats. Marked decrease of nerve conduction velocity and prolonged duration were found in A alpha beta and A delta fibers especially in large myelinated A alpha beta fibers. The amplitude decreased in A alpha beta potential, but the area did not change. In C potential produced by activation of unmyelinated fibers, nerve conduction velocity slightly decreased, but the amplitude and area did not significantly change. Pathologic correlates revealed prominent segmental demyelination with significant decrease of large myelinated fiber densities. Minimal axonal degeneration of unmyelinated fibers was present. We can conclude that electrophysiologic changes in the lead-poisoned rats correlate with pathologic changes in them.     

Localization of the cell activator lipopeptide in bone marrow-derived macrophages by electron energy loss spectroscopy (EELS)

Synthetic lipopeptide analogues of bacterial lipoprotein constitute potent polyclonal activators for monocytes/macrophages and B lymphocytes. However, the fate of the lipopeptides after their interaction with target cells is as yet unknown. In order to follow the routes and to determine the distribution of the lipopeptide within macrophages after stimulation, we investigated lipopeptide-stimulated bone marrow-derived macrophages using the novel method of electron energy loss spectroscopy (EELS). Our results show that the lipopeptide was present in different compartments of the cell. The major amount of the activator was located within the cytoplasm and the plasma membrane, and minor quantities were detected within the nuclear membrane and the nucleus. The distribution of the lipopeptides varied depending on the duration of stimulation. Our results should help to elucidate the molecular mechanisms of macrophage stimulation by lipopeptides or other cell activators.     

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.     

First serologic evidence of human spotted fever group rickettsiosis in Korea

To investigate the prevalence of spotted fever group rickettsioses in Korea, a serosurvey of Japanese spotted fever rickettsiosis in patients with acute febrile illness was conducted with an indirect immunofluorescence assay. Overall, 19.88% of the patients were found to have polyvalent antibody against Rickettsia japonica. This study is the first documentation of spotted fever group rickettsiosis in Korea.     

Administration of agonistic anti-4-1BB monoclonal antibody leads to the amelioration of inflammatory bowel disease

4-1BB (CDw 137), a member of the tumor necrosis factor receptor (TNFR) superfamily, is a costimulatory receptor primarily expressed on activated T cells. It has been shown that the administration of agonistic anti-4-1BB monoclonal antibody (mAb) enhances tumor immunity and allogenic immune responses. Paradoxically, we found that the administration of anti-4-1BB mAb reduced the incidence and severity of inflammatory bowel disease. In this study, we investigated the effects of anti-4-1BB mAb in a murine intestinal inflammation model, which induced by the hapten reagent, 2,4,6-trinitrobenzene sulfonic acid (TNBS) and mimics immunologic characteristics of human Crohn's disease (CD). Colitis was induced by rectal administration of 2mg of TNBS in 35% ethanol using a vinyl catheter positioned 4cm from the anus. All mice were sacrificed 3 and 10 days after the TNBS administration. The disease activity index (DAI), histological changes of the colon and production of cytokines (IL-2, IL-4, IL-10 and IFN-gamma) were evaluated. The surface molecules of T cells in peripheral blood, spleen and mesenteric lymph nodes were analyzed by flow cytometry. When mice were treated with anti-4-1BB mAb, improvement in both wasting and histopathologic signs of colonic inflammation was observed. The increase a number of splenic CD4(+)CD25(+) T cells and decreased synthesis of the Th1 cytokine IL-2 also occurred. Interestingly, increased production of Th1 cytokine IFN-gamma and proportion of CD8(+) T cells were observed in mice treated with anti-4-1BB mAb in comparison to the colitic mice. These studies show, for the first time, that agonistic anti-4-1BB mAb can improve experimental colitis by reduction of IL-2 and augmentation of CD4(+)CD25(+) regulatory T cells. TNBS colitis is Th1-mediated and has similar histologic features and distribution of inflammation to CD. This study suggests that anti-4-1BB mAb therapy could be effective in the treatment of patients with CD.     

Immunogenicity and Safety of Two Different Haemophilus influenzae Type b Conjugate Vaccines in Korean Infants

The incidence of invasive diseases, including meningitis caused by Haemophilus influenzae type b (Hib) was markedly decreased after routine immunization of Hib vaccine through diverse schedules in many countries. The purpose of this study was to evaluate the immunogenicity and safety of Hib conjugate vaccines in Korean children before the implementation of a national immunization program against Hib in Korea. A multicenter controlled trial was performed on two different Hib vaccines in Korean children. A total of 319 infants were enrolled: 199 infants were immunized with the Hib polysaccharide conjugated to the tetanus toxoid (PRP-T) and 120 infants with the Hib polysaccharide conjugated to the outer-membrane protein of Neisseria meningitides (PRP-OMP). Immunogenicity was evaluated by enzyme-linked immunosorbent assay (ELISA) and serum bactericidal assay. Both vaccines showed good immunologic responses after primary immunization. After 2 doses of PRP-T or PRP-OMP, 78.9% and 91.7% of infants achieved an antibody level of ≥1.0 µg/mL, respectively. Both vaccines were safe and well-tolerated. No serious adverse events were observed. Thus, Hib conjugate vaccines appear to be safe and show good immunogenicity in Korean infants. These results will be important reference data for the implementation of Hib vaccine in the national immunization program of Korea.     

Expression of cell cycle regulators during smooth muscle cell proliferation after balloon catheter injury of rat artery

Intimal hyperplasia is defined as the abnormal migration and proliferation of vascular smooth muscle cells (VSMCs) with deposition of extracellular matrix. However, the cell cycle regulatory mechanisms of injury-induced VSMC proliferation are largely unknown. To examine the expression kinetics of cell cycle regulatory factors which is known to be worked positively or negatively, we used rat balloon injury model. Marked induction of proliferating cell nuclear antigen (PCNA), G1/S cyclin-dependent kinase (cdk2), and its regulatory subunit (cyclin E) occurred between 1 and 3 days after balloon arterial injury, and this was sustained for up to 7 days and then declined. However, the induction of the negative regulators, p21 and p27, occurred between 3 and 5 days of injury, peaked after 7 and 14 days and was then sustained. VSMC proliferation after balloon catheter injury of the rat iliac artery is associated with coordinated expression of positive (cdk2, cyclin E and PCNA) and negative (p21, p27) regulators. Cell cycle regulators such as cdk2, cyclin E, p21, p27 may be suitable targets for the control of intimal hyperplasia.     

Isolation and partial characterization of circulating immune complexes in sera of children with HBV-mediated glomerulonephritis.

Circulating immune complexes (CIC) containing HBsAg and HBeAg were identified in sera of 5 out of 6 children with hepatitis B mediated membranous glomerulonephritis. CIC were precipitated from sera by 3.5% PEG, washed and subsequently analysed after acid dissociation and trypsin digestion. HBsAg, anti-HBs and albumin; HBeAg, anti-HBe and anti-HBc were recovered from the isolated complexes and these findings are discussed. Analysis of 3.5% PEG mediated precipitate of human serum proteins showed the relatively high content of IgG classical pathway complement components: C1q, C4 and C3.