Biomedical subjects

A Allan

Publications and source records attributed to A Allan.

77 records · Page 5Linked to original sources

PubMedDate not supplied

Macrophage-like cell line (HS-P) from a rat histiocytic sarcoma.

With future exploration of macrophage properties in mind, we established a novel cell line (HS-P) from a transplantable histiocytic sarcoma, derived originally from a tumour in an aged F344 rat. HS-P was subjected to 70 serial passages, in which the mean doubling time was 15.7 h. The cells, which were round, oval or polygonal in shape, were arranged in a compact sheet. They reacted to varying degrees for lysosomal enzymes (acid phosphatase and non-specific esterase) and with the following antibodies: ED1/ED2 (rat macrophage/histiocyte-specific), OX6 (rat MHC class II-specific), lysozyme antibody and alpha1-antichymotrypsin antibody. Electron microscopically, HS-P cells showed lysosomes and prominent cell projections. These findings indicated that the cultured cells were macrophage-like. Syngeneic rats inoculated subcutaneously or intraperitoneally with HS-P cells invariably developed sarcomatous tumours consisting of monomorphic mononuclear cells, which exhibited cytochemical properties similar to those of cultured HS-P cells. Bioassay and reverse transcription-polymerase chain reaction methods revealed that tumour necrosis factor-alpha increased on addition of lipopolysaccharide (LPS), indicating that HS-P cells remained LPS-responsive. HS-P cells may prove to be a useful tool for in-vitro studies of macrophage function.

Acid Phosphatase↗

PubMedDate not supplied

Differential effects of transforming growth factor-beta1, a fibrogenic factor, on macrophage-like cells (HS-P) and myofibroblastic cells (MT-9) in vitro.

Transforming growth factor-beta1 (TGF-beta1) produced by infiltrating macrophages plays a role in fibrotic disorders through the induction of myofibroblasts. To explore possible mechanisms by which TGF-beta1 may act in this context, we investigated effects of TGF-beta1 on macrophage-like (HS-P) and myofibroblastic (MT-9) cells, two novel cell lines developed by us. Immunocytochemically, the addition of TGF-beta1 (0, 0.1, 0.5, and 1.0 ng/ml) dose-dependently suppressed the expressions of antigens recognized by macrophage/histiocyte-specific antibodies (ED1 and ED2) in HS-P cells, whereas the addition concomitantly increased the number of anti-alpha-smooth muscle actin antibody-positive myofibroblastic cells, suggesting a possible phenotypical modulation of macrophages into myofibroblasts in the fibrotic lesions. By contrast, MT-9 cells did not show such immunophenotypical changes following TGF-beta1 addition. DNA synthesis, measured by tritiated thymidine-incorporation, was inhibited in a dose-dependent manner in MT-9 cells by TGF-beta1 addition (0, 0.1, 0.2, 0.5, 1.0, 5, and 10 ng/ml), but that in HS-P cells was unchanged. Northern blot analysis revealed that expressions of cell cycle-related early genes, c-jun and c-myc, were increased in HS-P cells after TGF-beta1 (1 ng/ml) addition, with c-jun showing peak expression prior to c-myc. By contrast, the peak expressions of c-jun and c-myc were delayed in TGF-beta1 (1 ng/ml)-added MT-9 cells, and their levels were less in MT-9 cells than in HS-P cells. Furthermore, TGF-beta1 (1 and 10 ng/ml) induced DNA laddering in MT-9 cells, but did not in HS-P cells. Based on these findings, it was speculated that TGF-beta1 could have induced G1 arrest in cell cycle and apoptosis in MT-9 cells. The present study showed that there were significant differences in the effects of TGF-beta1 between macrophage-like HS-P cells and myofibroblastic MT-9 cells, presumably depending on divergent susceptibilities to TGF-beta1 between both cell types. Because such cell types are key cells in the fibrogenesis, HS-P and MT-9 might be useful models for investigating the pathogenesis of fibrosis in vitro.

Animals↗

PubMedDate not supplied

Truth and reconciliation: a psycholegal perspective.

The South African Truth and Reconciliation Commission ('TRC') represents one model of dealing with human rights abuses at a national level. Such abuses, and the subsequent attempts to come to terms with them, can cause mental disorders and psychological pain. Consequently, mental health and mental health practitioners ('practitioners') will play an important role in the process of bodies such as the TRC. The aim of this article is to examine the TRC process from a psycholegal perspective and to recommend which aspects thereof can be improved in the future. For example, the use of terminology such as 'victim' and 'perpetrator' during the process may have influenced how participants were perceived and treated. Likewise, the emphasis on collective, rather than individual interests, restricted the role of survivors and amnesty seekers in the TRC process. This reduced the effectiveness of the TRC in bringing about reconciliation at an individual and a national level, and limited the TRC's potential as a therapeutic agent. Nevertheless, there were claims that the TRC process healed people. It is argued that the process in itself usually did not lead to healing. Instead, the TRC process highlighted great mental health needs, which were not adequately met. The article discusses the factors that make it difficult to meet mental health needs in countries where human rights abuses have taken place. The article then considers strategies to meet these needs and emphasizes how important it is that those who render mental health services are competent and seen to be credible by the consumers of such services. Finally, the article addresses the need for research in this field to be co-ordinated and professionally responsible.

Ethnicity↗

PubMedDate not supplied

In vitro evaluation of an implantable left ventricular assist device.

The development of implantable left ventricular assist devices (LVADs) has almost reached the stage of providing permanent circulatory support in patients who are unsuitable for, or denied, the transplant option. As part of our ongoing haemodynamic evaluation of the Thermo Cardiosystems Inc. (Boston, USA) Mark 14 pneumatic LVAD, pressure-volume loops have been produced from in vitro studies using a modified National Heart Lung and Blood Institute (NHLBI, USA) mock circulatory loop. These studies have demonstrated that during certain phases of the pump cycle non-physiologically high and low pressures are generated within the LVAD. Such abnormal pressures may damage either the bioprosthetic valves in the LVAD or the native heart, and may have adverse effects on cardiovascular control mechanisms.

Evaluation Studies as Topic↗

PubMedDate not supplied

Development of a polyurethane percutaneous access device for long-term vascular access.

The percutaneous placement of intravascular devices creates a portal for microbial invasion that can result in local infections or septicemia. In nature, resistance to "exist site" infection in percutaneous organs, such as teeth, is prevented by a dense collagen/epithelial barrier. A new percutaneous access device has been developed that incorporates a porous polyurethane "button" at the subdermal level. This device promotes the development of a collagen/epithelial interface, thus inhibiting sinus formation. Twelve percutaneous access devices (PCADS) were implanted in calves; eight devices were utilized for venting of, and hard wire passage to, an implantable left ventricular assist device (LVAD) and served as controls. Four devices were utilized for long-term vascular access. The PCADS remained in situ for 2-127 days (mean 70). Excellent healing was apparent in all cases, and no exit site or catheter related infections occurred. Histologic examination demonstrated fibroblastic in-growth and collagen deposition within the porous polyurethane, which provides a barrier to epithelial migration and firmly anchors the device. These PCADS appear to reduce exit site infections and may improve upon currently available long-term vascular access catheters.

Animals↗