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Biomedical subjects

M A Bach

Publications and source records attributed to M A Bach.

At least 19 recordsLinked to original sources
PubMed1992

Anti-peripheral nerve antibodies in leprosy patients recognize an epitope shared by the M. leprae 65 kDa heat shock protein.

Binding of leprosy sera to peripheral nerve from different species (mouse, guinea pig and rabbit) was evaluated by ELISA. A majority of sera, whatever the clinical form of leprosy, bind to these antigens. Absorption with Mycobacterium bovis BCG demonstrated that these antibodies recognize cross-reactive epitopes between peripheral nerve and mycobacteria. In immunoblot analysis, both leprosy patient sera and a monoclonal antibody directed at the 65 kDa heat shock protein of M. leprae were shown to react with a heat-shock 67-68 kDa sciatic nerve protein. Binding of the monoclonal antibody to this sciatic nerve antigen was prevented by incubation with lepromatous patient sera, showing that some peripheral nerve epitopes recognized by patient antibodies are shared by the 65 kDa heat shock protein of M. leprae.

Animals↗
PubMed1992

Myalgia and elevated creatine kinase activity associated with subcutaneous injections of diluent.

A 16-year-old boy with short stature and mild primary hypothyroidism received subcutaneous injections of either recombinant human growth hormone or placebo in diluent that contained glycerol and m-cresol as a preservative. While he was receiving the study drug, myalgia developed and serum creatine kinase values were elevated. Both resolved when injections were stopped and recurred when injections of diluent alone were given. The myalgia and elevated creatine kinase activity were apparently caused by a component of the diluent.

Adolescent↗
PubMed1992

T-cell receptor identification of an oligodendrocyte-specific autoreactive cytotoxic T-cell clone without self restriction.

In addition to myelin basic protein (MBP) and proteolipid protein (PLP), oligodendrocyte (Od) membrane autoantigens, such as the glycoprotein M2/MOG, could participate in the pathogenesis of autoimmune demyelinating diseases of the central nervous system (CNS), such as experimental allergic encephalomyelitis (EAE) or multiple sclerosis (MS). We have described an Od-specific autoreactive and cytotoxic T-cell clone, named C2, which recognized M2/MOG without conventional MHC restriction. In order to analyse the Od/C2 interaction, we determined the alpha/beta T-cell receptor (TCR) variable region usages and structures of C2. Monoclonal antibody stainings of C2 and nucleotide sequences show that the alpha chain is composed of a V alpha 5 and a J alpha identical to J alpha 18BBM142 gene segments, and that the TCR beta chain is composed of V beta 17a, D beta 2.1 and J beta 2.2 gene segments indicating that C2 used a conventional alpha/beta TCR for M2/MOG recognition.

Amino Acid Sequence↗
PubMed1992

Anatomy of the pituitary insulin-like growth factor system.

In situ hybridization was used to map patterns of gene expression for components of the insulin-like growth factor (IGF) system, including IGF-I and -II, IGF-binding proteins 1-5 (IGFBP1-5), the IGF-I receptor, and GH in the rat pituitary. IGF-I mRNA was concentrated in isolated cells scattered throughout the gland with features typical of nonendocrine folliculo-stellate cells. IGF-II mRNA was abundant in neural (NL) and intermediate lobe (IL) capillaries, and low levels were present in endocrine cells of anterior lobe (AL) and IL. IGFBP1 mRNA was not detected in the pituitary. IGFBP2 mRNA was concentrated in epithelial cells lining AL follicles and in astroglial-like cells (pituicytes) of the NL. IGFBP3 mRNA was localized in isolated cells scattered throughout the AL and NL. IGFBP4 mRNA was relatively abundant in NL pituicytes and was diffusely expressed in the AL. IGFBP5 mRNA was equally abundant in NL and AL, and was localized in folliculo-stellate and epithelial cells of the AL and pituicytes and capillaries of the NL. Neither IGF-I nor IGFBP1-5 were detected in the IL. IGF-I receptor mRNA was abundant and homogeneously distributed throughout the AL and IL, compatible with expression by endocrine cells. There was overlap, but no particular correlation, between IGF system gene expression and GH-producing cells, which were clustered in the dorsal-lateral wings of the AL. In summary, IGF system gene expression is bountiful in the rat pituitary, but does not correlate with sites of GH synthesis. IGF-I receptor mRNA, which might have been expected to localize to somatotrophs, appears to be equally abundant in all of the endocrine cells of both AL and IL; the other constituents of the IGF system are localized in connective tissue and support elements that demonstrate no special anatomical relationship to somatotrophs. Finally, there is remarkably abundant gene expression for IGFBP2, -4, and -5 in the NL.

Animals↗
PubMed1992

Structural and functional analysis of the insulin-like growth factor I receptor gene promoter.

The insulin-like growth factor I receptor (IGF-I-R) gene is expressed in most body tissues. The levels of IGF-I-R mRNA, however, are regulated by a number of physiological conditions (development, differentiation, and hormonal milieu) as well as in certain pathological states (diabetes and tumors). To understand the molecular mechanisms which control the transcription of the IGF-I-R gene, we have cloned the promoter of the rat receptor gene and have characterized its activity by transient expression assays. Different fragments of the 5'-flanking region (subcloned upstream of a luciferase reporter gene) were transfected into buffalo rat liver 3A cells (a cell line with a low number of IGF-I binding sites) and Chinese hamster ovary cells (a cell line with a higher number of cell-surface receptors). In both cell lines, most of the promoter activity was located in the proximal 416 base pairs of 5'-flanking region. However, further dissection of this proximal fragment revealed a cell type-specific pattern of promoter activity. Thus, in buffalo rat liver 3A cells, subfragments of this region each contributed to total activity, suggesting that contiguous cis-elements can act together to activate transcription. In Chinese hamster ovary cells, on the other hand, subfragments of the proximal promoter region partially substituted for the proximal 416 base pairs of 5'-flanking region. Coexpression studies using an IGF-I-R promoter reporter construct together with an Sp1 expression vector (under the control of an ADH promoter) were performed in SL2 cells, a Drosophila cell line which lacks endogenous Sp1. The results obtained showed that Sp1 can trans-activate the IGF-I-R promoter in vivo. Transient transfection assays were complemented with gel-retardation assays and DNase I footprinting experiments, which showed that transcription factor Sp1 is potentially an important regulator of IGF-I-R gene expression.

Animals↗
PubMed1991

Restricted T-cell receptor V beta gene usage by myelin basic protein-specific T-cell clones in multiple sclerosis: predominant genes vary in individuals.

Recent studies in experimental autoimmune encephalomyelitis as a model for multiple sclerosis (MS) have demonstrated limited heterogeneity in T-cell antigen receptors (TCR) specific for myelin basic protein (MBP). To investigate restricted beta-chain variable-region (V beta) gene usage in humans, we analyzed TCR gene rearrangements in two lines and 34 MBP-specific T-cell clones that were isolated from five MS patients and two healthy subjects. The T cells were characterized for their specificity to MBP epitopes and HLA-restricting molecules. We demonstrate here that MBP-specific T-cell clones from these different MS patients and healthy individuals, in contrast to T cells from rodents, display a more diverse V beta gene usage as evidenced by their TCR V beta gene rearrangements. However, the different MBP-specific T-cell clones isolated from each individual MS patient showed a common V beta gene usage, suggesting individual-specific TCR restriction. Out of 16 MBP-specific clones derived from a single MS patient, 12 clones (75%) utilized the V beta 15 gene for their TCR gene rearrangement. MBP-specific clones isolated from four other MS patients also showed a consistent tendency for a predominant, but different, TCR V beta gene rearrangement. These results suggest a TCR heterogeneity among MBP-specific T-cell clones from different individuals but a limited TCR V beta gene usage among MBP-specific T-cell clones of the same individual. The predominant V beta gene used by the MBP-specific T-cell clones studied here was not found to correlate with the epitope specificity of T cells or with their restricting HLA molecule. These findings may support the possibility of intervention with monoclonal antibodies to specific V beta gene products as an approach to immune therapy of MS but also imply the necessity for an individual-specific immunotherapeutic approach.

Base Sequence↗
PubMed1991

T cell response to myelin basic protein epitopes in multiple sclerosis patients and healthy subjects.

T cell lines and clones specific for human myelin basic protein (BP) were selected from three multiple sclerosis (MS) patients and two healthy subjects and tested for their proliferative responses to a battery of synthetic peptides, 9 to 21 amino acid residues long. The combined amino acid sequence of the peptides spanned the complete sequence of the human BP. The results suggest the development of T cells sensitized to at least four independent regions of the human BP, indicating some diversity of the human T cell repertoire to BP. However, an immunodominant T cell epitope was located in the C-terminal region, defined by residues 149-162. This epitope was recognized by T cells from three subjects out of five (one MS patient and both healthy controls) in the context of different DR specificities. Another epitope (located in the 57-75 region) which triggered one MS patient's T cell response was also recognized by a mycobacteria-specific T cell clone cross-reacting with BP.

Epitopes↗
PubMed1991

Strain differences in mouse cellular responses to Mycobacterium lepraemurium and BCG subcutaneous infections. II. Production of interleukins 2, 4, and 6 and of interferon-gamma by draining lymph node cells.

C57BL/6, BALB/c, and CBA mice were infected either by Mycobacterium bovis BCG or by M. lepraemurium (MLM). Interleukins (IL) 2, 4 and 6 and interferon-gamma (IFN-gamma) were measured in the supernatants of draining lymph node cells (DLN) or control lymph node cells from uninfected mice, restimulated in vitro by the heat-killed infecting Mycobacterium. Uninfected lymph node cells did not develop any IL4, IL2, and IFN-gamma response to BCG and MLM. A significant IL6 response to BCG was observed, with CBA being the best producer and C57BL/6 the weakest. BCG-infected mice, which controlled the BCG infection, displayed variable patterns of lymphokine response to BCG according to the strain. C57BL/6 DLN cells produced more IL6 and IFN-gamma than IL2, whereas BALB/c mice produced more IL2. CBA secreted lymphokines with a similar pattern to that of BALB/c but in lower amounts. IL4 was not detected in any supernatant. MLM-infected mice displayed variable susceptibilities to MLM infection: C57BL/6 was resistant, BALB/c was susceptible after an initial efficient control, and CBA was fully susceptible. In each strain the lymphokine response to MLM was much lower than that triggered by BCG, but the pattern was similar. Thus, C57BL/6 DLN cells still produced significants amounts of IL2, IL6, and IFN-gamma, whereas BALB/c secreted IL2 alone and CBA did not produce any detectable lymphokine. IL4 was again not detected in any supernatant. The failure of BALB/c and CBA strains to develop IFN-gamma and IL6 responses to MLM might contribute to their low resistance to this infection.

Animals↗
PubMed1991

Insulin-like growth factor I mRNA levels are developmentally regulated in specific regions of the rat brain.

The expression of mRNAs encoding insulin-like growth factor I (IGF-I) and the IGF-I receptor in the developing rat brain from embryonic day 16 to postnatal day 82 was analyzed using solution hybridization-RNase protection assays. Four distinct developmental patterns in the steady-state levels of IGF-I mRNA were seen. Specifically, the olfactory bulb showed a high perinatal level of IGF-I mRNA which declined dramatically by postnatal day 8. In contrast, cerebral cortex displayed maximal levels of IGF-I mRNA at postnatal day 8 and 13, which subsequently declined to adult levels (P82). A third developmental pattern was seen in the hypothalamus, where IGF-I mRNA increased from E16 up to postnatal day 3 and remained elevated thereafter. Finally, IGF-I mRNA levels in brainstem and cerebellum remained unchanged throughout the time period studied. We conclude that there are specific regional patterns of IGF-I gene expression in the developing rat brain. In contrast, IGF-I receptor gene expression did not exhibit any region-specific developmental changes. The developmental patterns of IGF-I gene expression seen in this study further substantiate the potential role of IGF-I in normal brain development.

Amino Acid Sequence↗
PubMed1991

M. leprae- and BCG-induced chemiluminescence response of monocytes from leprosy patients and healthy subjects: effects of gamma-interferon and GM-CSF.

Mycobacterium leprae, in contrast to BCG, failed to trigger any chemiluminescence (CL) response in mononuclear cells from either leprosy patients or healthy subjects, a deficit not reversed by either interferon-gamma or GM-CSF. Chemiluminescence responses induced without mycobacteria or with BCG were found to be lower in leprosy patients than in controls. M. leprae were also less well phagocytosed than BCG. However, there was a significant difference in phagocytosis between healthy and tuberculoid leprosy subjects. Phagocytosis was not altered by the addition of either lymphokine, and no major differences between healthy subjects and patients were observed. Preincubating mononuclear cells with anti-mycobacteria antibodies (lepromatous patients' sera) did not increase the CL response nor the phagocytosis of M. leprae or BCG.

Antibodies, Bacterial↗
PubMed1990

Cloning and characterization of the proximal promoter region of the rat insulin-like growth factor I (IGF-I) receptor gene.

We have isolated genomic clones that contain the promoter region of the rat IGF-I receptor gene. A unique transcriptional start site was suggested by the results of primer extension and RNase protection assays, which also defined a 940-base 5'-untranslated region. Despite the single start site, the proximal 415 base pairs of 5'-flanking region were devoid of TATA or CCAAT elements. The region surrounding the start site was, however, similar to a recently described "initiator" sequence that can direct specific transcription initiation in the absence of a TATA element. The 5'-flanking region was GC-rich and contained several possible SP1 sites, but also included potential ETF and AP-2 binding sites. The rat IGF-I receptor gene promoter region appears to have some sequences similar to both "housekeeping" and highly regulated promoters and may be an example of an intermediary class of regulatory region.

Animals↗
PubMed1990

Alternative splicing produces messenger RNAs encoding insulin-like growth factor-I prohormones that are differentially glycosylated in vitro.

Rat insulin-like growth factor-I (IGF-I) cDNA sequences predict two prohormones that differ in the carboxy-terminal extension peptide (E-peptide) as a result of the inclusion or exclusion of the 52-basepair exon 4 sequence. In the absence of exon 4, the sequence codes for the IGF-Ia prohormone, whose E region contains two potential N-glycosylation sites. With differential splicing and the inclusion of exon 4, the resultant mRNA codes for IGF-Ib, with a longer E-region sequence. In addition, as a consequence of a frame shift, both potential glycosylation sites are lost in the IGF-Ib peptide. We used an in vitro translation system supplemented with canine pancreatic microsomal membranes to analyze cotranslational processing of the IGF-I propeptides. We have demonstrated that IGF-Ia prohormone, which contains two potential N-glycosylation sites in the E region, can be N-glycosylated in vitro, and that both glycosylation sites are probably used. As expected, the IGF-Ib preprohormone is processed by microsomes, but is not glycosylated.

Animals↗
PubMed1990

Strain differences in mouse cellular responses to Mycobacterium lepraemurium and BCG subcutaneous infections. I. Analysis of cell surface phenotype in local granulomas.

C57BL/6, BALB/c and CBA mice were subcutaneously infected with either Mycobacterium lepraemurium (MLM) or BCG, and studied for bacillary growth, granuloma size of infected footpads and draining lymph nodes (DLN), and DLN cell surface phenotype. Whereas, BCG-infected mice controlled the infection and developed early and large granulomas, MLM-infected mice exhibited major strain variations in their resistance to the infection, as well as in the granuloma size and kinetics. C57BL/6 mice, highly resistant, displayed early and regressive granulomas; BALB/c mice showed lower resistance and early granulomas that grew continuously; CBA mice, highly susceptible, developed late, soft, phagocyte-rich granulomas. Important strain differences in lymph node lymphocyte subset distribution could be observed prior to any infection: C57BL/6 mice displayed higher B cell percentages than both of the other strains and BALB/c mice showed the highest CD4/CD8 ratios, followed by CBA and C57BL/6 mice. BCG and MLM infections both induced similar changes of these parameters in all three strains: that is a decrease of the B cell percentage and a decrease of the CD4/CD8 ratio, and the strain differences observed in uninfected mice persisted. On the other hand, DLN cells stimulated by the infecting bacillus and interleukin 2 also displayed an increase of the CD8 T cell percentage as compared with normal lymph node cells, but this phenomenon was much less pronounced in BALB/c mice, whether infected by MLM or BCG, and in MLM-infected CBA mice, than in BCG- or MLM-infected C57BL/6 (B6) mice. Thus the ability of C57BL/6 mice to generate an early and persistent CD8 T cell response to mycobacteria may contribute to their resistance to MLM.

Animals↗
PubMed1989

Human phagocyte oxidative burst activation by BCG, M. leprae, and atypical mycobacteria: defective activation by M. leprae is not reversed by interferon gamma.

The activation of the phagocyte oxidative respiratory burst by various mycobacteria was evaluated in an in vitro assay, by measuring the chemiluminescence, associated to the release of oxidizing species, generated by normal human whole blood phagocytes. All mycobacterium species, except Mycobacterium leprae, induced a significant chemiluminescence response. The strongest stimulus was provided by BCG, followed by M. triviale, M. chelonei, and M. fortuitum. M. kansasii, M. intracellulare, and M. lepraemurium elicited a weak response, although higher than that triggered by M. leprae. Both polymorphonuclear and mononuclear cells contributed to the whole blood cell chemiluminescence stimulated by mycobacteria, mononuclear cells being more efficient on a per cell basis. Phagocyte activation by recombinant interferon gamma did not improve M. leprae ability to trigger a significant chemiluminescence response. The failure of M. leprae and of some atypical mycobacteria to stimulate a strong phagocyte oxidative respiratory burst may have some relevance to their pathogenicity.

Adult↗
PubMed1989

Lymphocyte proliferative response to glial cells in SJL/J mice immunized with rat whole spinal cord and rat myelin basic protein.

Lymph node cells (LNC) from SJL/J mice immunized with either rat whole spinal cord (WSC) homogenate or rat myelin basic protein (MBP) in the presence of complete Freund's adjuvant were assayed for their in vitro proliferative response to MBP and whole or sonicated purified oligodendrocytes (OD), and astrocytes. WSC-immunized mice displayed a strong and persistent response to both syngeneic and rat OD, that disappeared after sonication (suggesting a preferential recognition of surface OD antigen(s], and a much weaker response to rat MBP. LNC from MBP-immunized mice showed a small response to MBP, but no response to OD, indicating that OD are not able to present their endogenous MBP to lymphocytes. Conversely, rat astrocytes (whole or sonicated), isolated from cultures initially comprising OD, could trigger the proliferative response of MBP-sensitized LNC, suggesting that astrocytes may act as antigen-presenting cells for OD products.

Animals↗
PubMed1989

Influence of thymic hormone on cell-mediated and humoral immune responses in Marek's disease.

A reduction in the secretion of thymic hormones, and in particular thymulin, can be demonstrated in chickens following the thymic atrophy induced by Marek's disease virus (MDV) infection. In very sensitive histocompatible (B13/B13) chickens inoculated with the HPRS-16 strain of MDV at 10 days of age, treatment with synthetic thymulin by daily subcutaneous injection failed to modify the time course of Marek's disease (MD) and did not prevent the development of macroscopic tumors. No effect was noted on the levels of neutralizing anti-viral antibodies. Nevertheless, thymulin treatment resulted in significant suppression of the cellular immune response 4-6 weeks post-inoculation, monitored by splenic cytotoxicity against MD-specific and natural killer-sensitive lymphoblastoid cell lines.

Animals↗