The morphology and mechanical properties of endomysium in series-fibred muscles: variations with muscle length

Summary In the series-fibred muscle architecture commonly found in large muscles of mammals and birds, the intrafasciculary-terminating muscle fibres have no direct tendinous attachments. Contractile force produced in these fibres must be transmitted between adjacent muscle fibres via the endomysial connective tissue which separates them. The endomysium is thus an essential mechanical component in such muscles. Studies of motor end-plate banding patterns and the frequent occurrence of tapering ends of fibres within the fascicles of the bovine sternomandibularis muscle show it to be a series-fibred muscle. Sodium hydroxide digestion of fixed samples of this muscle to remove the myofibrillar apparatus revealed the endomysium to be a disordered planar network of mainly curvilinear collagen fibrils.The orientation distribution of the collagen fibrils in the endomysial network was measured by image analysis of scanning electron micrographs. Analysis of endomysial preparations from muscle fixed at sarcomere lengths between 1–4 m showed that the orientation distribution of collagen fibrils is quantitatively related to muscle length. At rest sarcomere length the collagen fibril network is not completely random, but has a slight circumferential bias. The orientation distribution shows a progressive shift towards the circumferential direction at short sarcomere lengths and towards the longitudinal direction at long sarcomere lengths. The relationship between the number-weighted mean collagen orientation and sarcomere length was compared to two geometric models of network behaviour, the isoareal and constant shape models. both fitted the data reasonably, although the constant shape model described the rate of change of mean orientation more closely.From fibrous composites theory, the reinforcement efficiency factor, was calculated from the measured collagen fibril orientation distributions. These calculations predict a non-linearly increasing longitudinal tensile modulus for the endomysium with increasing sarcomere length, in agreement with its known non-linear properties, but confirm that the tensile properties of the endomysium are unsuitable for transmission of tensile force from muscle fibres contracting near rest length. This reinforces a previous interpretation that contractile force is transmitted between neighbouring muscle fibres by trans-laminar shear through the endomysium rather than by in-plane tension.     

Characterization of a monoclonal anti-Bw4 antibody (Tü109): Evidence for similar epitopes on the Bw4 and Bw6 antigens

The production and serologic, as well as immunochemical properties of a cytotoxic murine IgG monoclonal antibody (Tü109) that precipitates HLA-class I molecules, are described. In the microcytotoxicity assay Tü109 supernatant was demonstrated on a panel of 424 HLA-ABC, -DR, -DQ, -MT typed normal Caucasian blood donors to define an epitope on HLA-B locus molecules in great association with the supertypic specificity Bw4. Reactivity of supernatant showed MHC linked inheritance of the Tü109 determinant and discriminated the HLA-Bw4/Bw6 associated HLA-B locus split antigens. Weak or lack of binding on lymphocytes from some HLA-Bw4 heterozygous individuals, particularly typing for HLA-Bw44, appeared to be due to qualitative and/or quantitative variations of HLA-B locus molecules on the cell surface. With Tü109 ascites fluid, however, extra-reactivity on all HLA-Bw6⁺ cells was demonstrated. Preferential binding of supernatant to HLA-Bw4, but reactivity of ascites fluid with HLA-Bw6⁺ molecules in addition, was furthermore confirmed by IEF analysis of antigens immunoprecipitated with Tü109 from cell lysates. Thus the antibody may help to analyze the evolutionary relationship of the diallelic specificities Bw4 and Bw6.     

Association of tuberculin-boosted antibody responses with pathology and cell-mediated immunity in cattle vaccinated with Mycobacterium bovis BCG and infected with M. bovis

Vaccine development and our understanding of the pathology of bovine tuberculosis in cattle would be greatly facilitated by definition of the immunological correlates of protection and/or pathology. In this study we analyzed humoral immune responses in Mycobacterium bovis BCG-vaccinated and control cattle (in particular, the relationship between the intradermal comparative tuberculin skin test and serum immunoglobulin G [IgG] responses) against a range of mycobacterial antigens (MPB59, MPB64, MPB70, MPB83, ESAT-6, CFP-10, Acr1, and PstS-1) by multiantigen print immunoassay and conventional enzyme-linked immunosorbent assay. Following M. bovis infection, the comparative tuberculin skin test strongly boosted IgG, IgG1, and IgG2 antibody responses, particularly against MPB83 and MPB70, in unvaccinated cattle but failed to boost these responses, or did so only weakly, in BCG-vaccinated calves. In addition, the skin test-induced increases in MPB83-specific IgG responses correlated positively with bacterial loads and ESAT-6-induced in vitro gamma interferon responses. In conclusion, both the negative correlation of skin test-enhanced MPB83-specific antibody responses with BCG-induced protection and their positive correlation with bacterial loads can serve as useful markers for vaccine efficacy after challenge.     

Depletion of peripheral blood T lymphocytes and NK cells during the course of ebola hemorrhagic Fever in cynomolgus macaques

During the course of an experimentally induced Ebola virus (EBOVA) infection of cynomolgus macaques, peripheral blood mononuclear cells were isolated and characterized by multi-color flow cytometry. Both CD4+ and CD8+ lymphocyte counts decreased 60-70% during the first 4 days after infection. Among CD8+ lymphocytes, this decline was greatest among the CD8(lo) population, which was composed mostly of CD3- CD16+ NK cells. In contrast, the number of CD20+ B lymphocytes in the blood did not significantly change during the course of the infection. Phenotypic analysis of T lymphocyte subsets by flow cytometry failed to show evidence of a robust immune response to the infection. Apoptosis could be detected as early as day 2 postinfection among the CD8+ and CD16+ subsets of lymphocytes. Increased expression of CD95 (Fas) suggests that apoptosis may be induced via signaling through the Fas/Fas-L cascade. In contrast, the number of HLA-DR+ cells increased tenfold in the blood during the course of infection. These data suggest that EBOV may block dendritic cell maturation after infection, thereby inhibiting activation of lymphocytes and eliminating those subsets that are most likely to be capable of mounting an effective response to the virus.     

The feasibility,demand, and effect of integrating primary care services with HIV voluntary counseling and testing: evaluation of a 15-year experience in Haiti, 1985-2000

BACKGROUND: HIV voluntary counseling and testing (VCT) may be an effective strategy to prevent transmission of HIV in developing countries. Hypothesizing that primary care services and HIV VCT have synergistic benefits, we examine the feasibility, the demand, and the effect of integrating on-site primary care services into VCT at a stand-alone VCT center in Port au Prince, Haiti. METHODS: Through a retrospective review of patient records, we describe the integration of primary care services at the Groupe Haitien d'Etude du Sarcome de Kaposi et des Infections Opportunistes (GHESKIO) VCT center between1985 and 2000. RESULTS: Between 1985 and 1999, services for HIV care, tuberculosis care, treatment of sexually transmitted diseases, and reproductive health were sequentially integrated into HIV VCT at GHESKIO. The number of new people seeking voluntary counseling and testing at GHESKIO increased from 142 in 1985 to 8175 in 1999, with an increasing percentage of women, adolescents, symptom-free clients, and self-referred clients. Of new adults seeking VCT in 1999, the center was able to provide AIDS care to 17%, tuberculosis treatment to 6%, sexually transmitted infection management to 18%, and family planning to 19%. HIV transmission between discordant couples was 0 infections/100 follow-up years (95% CI, 0-3.2); vertical transmission from mother to child was 11 infections/100 live births (95% CI, 4.6-21.9); These rates are significantly lower than expected rates of transmission in Haiti. CONCLUSIONS: This report demonstrates the feasibility, demand, and effective synergy of integrating on-site primary care services into HIV VCT in Haiti. VCT is a good entry point for people in need of services for communicable diseases and reproductive health, and, reciprocally, services attract more people to VCT, including populations that are at high risk for HIV infection. This program is being duplicated elsewhere in Haiti and can serve as a model for other countries.     

A mouse model of spinal and bulbar muscular atrophy

Spinal and bulbar muscular atrophy (SBMA) is an adult-onset motor neuron disease, caused by the expansion of a trinucleotide repeat (TNR) in exon 1 of the androgen receptor (AR) gene. This disorder is characterized by degeneration of motor and sensory neurons, proximal muscular atrophy, and endocrine abnormalities, such as gynecomastia and reduced fertility. We describe the development of a transgenic model of SBMA expressing a full-length human AR (hAR) cDNA carrying 65 (AR(65)) or 120 CAG repeats (AR(120)), with widespread expression driven by the cytomegalovirus promoter. Mice carrying the AR(120) transgene displayed behavioral and motor dysfunction, while mice carrying 65 CAG repeats showed a mild phenotype. Progressive muscle weakness and atrophy was observed in AR(120) mice and was associated with the loss of alpha-motor neurons in the spinal cord. There was no evidence of neurodegeneration in other brain structures. Motor dysfunction was observed in both male and female animals, showing that in SBMA the polyglutamine repeat expansion causes a dominant gain-of-function mutation in the AR. The male mice displayed a progressive reduction in sperm production consistent with testis defects reported in human patients. These mice represent the first model to reproduce the key features of SBMA, making them a useful resource for characterizing disease progression, and for testing therapeutic strategies for both polyglutamine and motor neuron diseases.     

Comparative genomic hybridization pattern distinguishes T-cell/histiocyte-rich B-cell lymphoma from nodular lymphocyte predominance Hodgkin's lymphoma

Several lines of evidences suggest that T cell/histiocyte-rich B-cell lymphoma (T/HRBCL) represents an aggressive variant of the clinically indolent entity nodular lymphocyte predominance Hodgkin's lymphoma (LPHL). Still, this view has not yet been supported by firm genetic evidence. In this study, we analyzed 17 T/HRBCL cases using comparative genomic hybridization (CGH) combined with microdissection of single CD20+ neoplastic cells and DNA amplification by degenerate oligonucleotide primed-polymerase chain reaction, an approach we previously used in LPHL. Genomic imbalances were detected in all cases (in total, 80 changes). The most common imbalances included gain of Xq, 4q13q28, Xp21p11, and 18q21, and loss of 17p. Of note, a partial gain of 4q, a rare change in lymphoma, is also among the genomic imbalances most frequently encountered in LPHL. On the other hand, the CGH profiles of T/HRBCL and LPHL showed several distinct features, in particular with respect to the number of genomic imbalances (average of 4.7 in T/HRBCL versus 10.8 in LPHL) and their distribution (usually 1 to 5 in T/HRBCL versus 6 to 22 in LPHL). Altogether, our CGH findings of shared as well as distinctive cytogenetic features in both diseases suggest that T/HRBCL constitutes a separate lymphoma entity, possibly originating from the same precursor cell as LPHL.