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Biomedical subjects

D Heymann

Publications and source records attributed to D Heymann.

84 records · Page 5Linked to original sources
PubMed1994

Microwave balloon angioplasty effectively seals arterial dissections in an atherosclerotic rabbit model.

OBJECTIVES: The purpose of this study was to determine the effectiveness of microwave balloon angioplasty in sealing arterial dissections and to characterize the histologic features associated with this intervention. BACKGROUND: Coronary dissection accompanying balloon dilation is frequently associated with abrupt closure and acute ischemic complications. Effective management of this complication remains an active area of investigation. Because thermal energy is effective in welding separated atherosclerotic plaques, a microwave-based catheter system that provides controlled local heating was utilized in vessels with angioplasty-induced dissections. METHODS: Iliac artery dissections were induced in ahypercholesterolemic rabbit model. Vessels were randomly assigned to treatment with standard balloon angioplasty (control vessels) or microwave balloon angioplasty using an average temperature of 80 degrees C. The response of the artery was assessed angiographically and histologically. RESULTS: Angiographic success, defined as a reduction of dissection length by > 50% or the resolution of lumen haziness, was achieved in 63% of microwave-treated vessels and in 16% of control vessels (p < 0.005). Dissection length (mean +/- SD) was reduced 8.0 +/- 4.8 mm in microwave-treated vessels compared with 0.1 +/- 7.9 mm in vessels receiving standard balloon inflations (p < 0.005). Cellular necrosis was more commonly observed in microwave-treated vessels than in control vessels (73% vs. 17%, p < 0.05), but less intraluminal thrombus was seen in vessels exposed to microwave energy (p < 0.05). CONCLUSIONS: Microwave balloon angioplasty is more effective than routine balloon inflations in sealing arterial dissections in this model and appears to be less thrombogenic in these markedly disrupted vessels.

Angiography↗
PubMed1993

Cell blotting and isoelectric focusing of neuroblastoma-derived heparin-binding neurotrophic activities: detection of basic fibroblast growth factor protein and mRNA.

Neuroblastoma cells have been shown to contain growth factors, which may be involved in the regulation of cell proliferation and/or differentiation. We have examined whether human IMR-32 neuroblastoma cells store factors with a capacity to promote neuron survival and differentiation. Heparin affinity chromatography, cell blotting, and isoelectric focusing of IMR-32 cell extracts revealed multiple neurotrophic activities at molecular weights of 16.8, 24.1, 39.0, 45.3, 52.3 and isoelectric points of 4.0, 5.0, 8.3, 9.0. Immunocytochemistry, immunoblotting, and radio-immunoassay with specific antibodies suggests that one neurotrophic activity is immunologically identical with basic fibroblast growth factor (bFGF). This assumption is supported by Northern blot analysis, which shows a 6.0 kb bFGF transcript.

Animals↗
PubMed1993

Reducing the cost of HIV antibody testing.

Available tests to detect antibody to human immunodeficiency virus (HIV) have a range of applications, and injudicious selection and inappropriate use can add a significant financial burden to budgets for AIDS programmes in developing countries. There are several ways by which the cost of HIV antibody testing can be reduced; they include use of tests appropriate for existing laboratory capabilities; adoption of cost-effective testing strategies; pooling of serum samples before testing; and ensuring best possible purchase prices. Each approach can significantly reduce the cost of HIV antibody testing alone or in combination, which increases the potential sustainability of antibody testing programmes, even in settings of limited resources.

AIDS Serodiagnosis↗
PubMed1992

High and low affinity receptors for human interleukin for DA cells/leukemia inhibitory factor on human cells. Molecular characterization and cellular distribution.

Radioiodinated recombinant human interleukin DA (HILDA)/leukemia inhibitory factor (LIF) purified from conditioned medium of Chinese hamster ovary transfected cells enabled the identification of specific receptor sites on a variety of human cell types. Using low concentrations (up to 500 pM) of the ligand iodinated at a high specific radioactivity, high affinity receptors (equilibrium dissociation constant Kd in the range of 30-100 pM) were first demonstrated. They were expressed at low levels by human peripheral blood monocytes but not by lymphocytes, NK cells, granulocytes, and platelets. The myelomonocytic cell line THP1 as well as the T lymphoma cell line HSB2 and the lymphoblastoid B cell line DAB were also receptor-negative. In contrast, most of the non-lymphoid tumoral cell lines tested, including melanomas, neuroblastomas, and carcinomas, expressed high affinity HILDA/LIF receptors at variable levels (Bmax from 20 to 600 sites/cell). The kinetics of HILDA/LIF high affinity binding to the choriocarcinoma JAR cell line were characterized at 4 degrees C with association and dissociation rate constants of k1 = 2.2 10(9) M-1 min-1 and k-1 = 0.0084 min-1, respectively, corresponding to a steady-state dissociation constant k1/k-1 = 3.8 pM. The subsequent use of higher concentrations of HILDA/LIF labeled at a lower specific radioactivity enabled the identification of a low affinity component on several cell lines (Kd in the range of 1-4 nM; Bmax from 1,000 to 5,000 sites/cell). On JAR cells, this low affinity component was characterized by association and dissociation rate constants at 4 degrees C of k1 = 7.3 10(7) M-1 min-1 and k-1 = 0.19 min-1, respectively (k-1/k1 = 2.6 nM). Affinity cross-linking of HILDA/LIF to JAR cells showed two cross-linked species under both reducing and nonreducing conditions corresponding to receptor species of 120 and 250 kDa, respectively. Whereas both bands had similar intensities under high affinity conditions, the higher band predominated under low affinity conditions. Our data suggest that the 250-kDa chain could constitute the low affinity binding component whereas the association of both 250- and 120-Da subunits would form the high affinity structure.

Animals↗
PubMed1990

Food-borne outbreak of Giardia lamblia.

An outbreak of giardiasis occurred following a family party for 25 persons. Nine who had eaten fruit salad became ill, compared with one who had not eaten the salad (Relative Risk = 7.4, 95% CI = 1.4, 169.3). The fruit salad preparer had a diapered child and a pet rabbit at home who were both positive for Giardia lamblia. This outbreak emphasizes the importance of good hygienic practices in food preparation and the possibility of domestic-animal-to-person transmission in Giardia outbreaks.

Animals↗
PubMed1989

Plasmodium falciparum associated placental pathology: a light and electron microscopic and immunohistologic study.

Pathological changes were studied by light and electron microscopy on term placentas collected in Malawi from 20 P. falciparum infected women (11 primiparas and 9 multiparas). One placenta from an uninfected term primipara and 4 from multiparas were studied as controls. Changes included the presence of parasitized erythrocytes and malarial pigment particles in the intervillous space, excessive syncytial knotting, chronic basal villitis, malarial pigment deposits in the trophoblasts, trophoblastic damage with focal necrosis, partial loss of microvilli, and thickening of the trophoblastic basement membrane. Infected erythrocytes were not seen in the fetal circulation. Severity appeared to correlate with the level of maternal and placental parasitemias, regardless of infant birth weight or placental weight. Differences in the severity of pathological changes between primiparas and multiparas could not be demonstrated. Immunohistochemistry revealed that 45% of the placentas stained strongly for IgG and 15% stained for C3 and for P. falciparum antigens in the trophoblastic cytoplasm and basement membrane.

Animals↗
PubMed1988

Immunogenicity and safety of measles vaccine in ill African children.

A concurrent prospective study was conducted in Rwanda to compare the immunogenicity and safety of live, attenuated measles vaccine in ill and well children. Five hundred and eighteen children aged 8 to 19 months were selected from children attending the acute care and immunization services of two clinics. Two hundred and sixty-seven ill children and 251 well children were enrolled and examined. Serological tests were performed on blood samples obtained before and 40 days after measles immunization. Among the 208 ill children and 215 well children who were seronegative at baseline and had unequivocal follow-up serological results, seroconversion rates were 81% and 80%, respectively. Side effects were modest and were equally frequent in the two study groups (15.4% among ill children versus 15.1% among well children). These results support a change in measles immunization policy in developing countries with respect to immunization of children with acute illnesses. Such a change would make a great contribution to decreasing the enormous burden of measles in the developing world through increased immunization coverage.

Antibodies, Viral↗
PubMed1984

Subcellular localization of 5'-nucleotidase in rat brain.

The subcellular distribution of the ectoenzyme, 5'-nucleotidase, in cerebral cortex and cerebellum of the rat was studied both biochemically and cytochemically. The fractions were characterized biochemically by marker enzymes. The localization of 5'-nucleotidase activity was also investigated cytochemically in the myelin, synaptosomal, mitochondrial, and microsomal fractions. Biochemically 5'-nucleotidase was found to be enriched in the membrane-containing fractions, i.e., myelin, synaptosomal, and microsomal fractions. Cytochemistry showed the reaction product in the myelin fraction to be associated with myelin profiles. In the synaptosomal fraction reaction product could occasionally be seen at synaptosomal membranes, although it could not be attributed unequivocally to the synaptosome itself, since in positions with reaction product unidentifiable membrane structures could always be seen attached. Mitochondria were virtually without any reaction product. In the microsomal fraction 5'-nucleotidase activity was associated with unidentifiable membrane structures. It is concluded that 5'-nucleotidase is associated with myelin profiles and that the high activity found in the synaptosomal fraction is probably not associated with nerve ending plasma membranes.

5'-Nucleotidase↗
PubMed1982

Identifying the reasons for low immunization coverage. A case study of Yaounde (United Republic of Cameroon).

Among the problems encountered today in Expanded Programmes on Immunization (EPI) is the failure to reach an acceptable level of immunization coverage in rapidly growing urban areas. This paper describes a checklist to identify the reasons for such low coverage. The checklist was first used in Yaounde, United Republic of Cameroon. There the low coverage is found to be associated with certain neighborhoods, one ethnic group, low socio-economic status, and newly-arrived families. Publicity about immunizations is not reaching Yaounde residents in those categories. Furthermore, health lessons (given only in French) seem to be confusing the parents rather than educating them. Finally, previous ineffective immunization programmes have made Yaounde residents mistrustful of the current programme. The authors recommend solutions to each of these Yaounde problems. The checklist, and the methods used for answering it in Yaounde, should prove useful to other immunization programmes.

Attitude to Health↗