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Biomedical subjects

L Vincent

Publications and source records attributed to L Vincent.

50 records · Page 3Linked to original sources
PubMed1980

Accumulation and overflow of 3H following incubation of the guinea-pig gall bladder with [3H]-noradrenaline.

1 Strips of guinea-pig gall bladder readily accumulate (3)H following incubation in the presence of 5 x 10(-8) M (-)-[(3)H]-noradrenaline. This accumulation was reduced by lowering the incubation temperature (from 37 degrees to 23 degrees C), by cocaine (10(-6) M), by nortriptyline (10(-8), 10(-6) and 10(-4) M) and following incubation of the tissues with 6-hydroxydopamine (10(-3) M for 3 h). At 10(-6) M, (-)-noradrenaline and (-)-adrenaline, but not (-)-isoprenaline, inhibited the accumulation of (3)H.2 Following preloading of strips of guinea-pig gall bladder with 3.6 x 10(-7) M (-)-[(3)H]-noradrenaline for 1 h, the spontaneous overflow of (3)H was observed. Cocaine (10(-4) M), nortriptyline (10(-6) M), (-)-isoprenaline (10(-5) M), acetylcholine (10(-5) M) and adenosine 5'-triphosphate (ATP, 10(-4) M) had no effect on the spontaneous overflow of (3)H. KCl (10(-1) M), (-)-noradrenaline (10(-5) M), (-)-adrenaline (10(-5) M), and tyramine (10(-5) M) increased the overflow of (3)H. These results illustrate similar characteristics of the guinea-pig gall bladder to other noradrenergically-innervated tissues in accumulating and releasing (3)H following incubation in the presence of [(3)H]-noradrenaline.3 Following incubation in the presence of 3.6 x 10(-7) M (-)-[(3)H]-noradrenaline, field stimulation, at 5 Hz, of strips of gall bladder, in the absence or presence of 10(-6) M atropine, increased the overflow of (3)H and, simultaneously, induced contractions. The contractile responses to 5 Hz were smaller in the presence than in the absence of 10(-4) M lignocaine. Lignocaine (10(-4) M) reduced the overflow of (3)H evoked by field stimulation at 5 Hz. It is suggested that the contractile responses to 5 Hz are due to nerve stimulation and that the increased overflow of (3)H is due to the stimulation of noradrenergic nerves.4 The overflow of (3)H evoked by field stimulation at 5 Hz was unaltered and increased by propranolol (10(-6) M) and phentolamine (10(-6) M), respectively. Clonidine (5 x 10(-5) M) had no effect in the absence but reduced the amount of (3)H which overflowed in response to field stimulation at 5 Hz in the presence of 10(-6) M atropine. The contractile responses to field stimulation at 5 Hz were reduced by phentolamine (10(-6) M) or clonidine (5 x 10(-6), 10(-5) and 5 x 10(-5) M) whether or not atropine (10(-6) M) was present. These results illustrate the presence of postsynaptic alpha-adrenoceptors and suggest the presence of presynaptic alpha-adrenoceptors in the gall bladder of the guinea-pig.

Animals↗
PubMed1980

The presence of two neuraminidases in an influenza virus.

The wild type influenza strain A/Aichi/2/68 (H3N2), when disrupted with SDS and electrophoresed on cellulose acetate paper, yielded two separate neuraminidases, NA(H+) and NA(H-). These enzymes after extraction were biologically active and possessed different specific activities. Enzyme NA(H+) possessed neuraminidase as well as hemagglutinin activities whereas enzyme NA(H-) demonstrated only neuraminidase activity. Similar results were obtained when the Aichi strain was treated with Tween-ether and the two enzymes were separated by affinity chromatography. Techniques used failed to separate the hemagglutinin activity from neuraminidase NA(H+). These results suggest that the dual activity present in enzyme NA(H+) may be characteristic of this protein. Both enzymes are antigenically different and are apparently present as distinct entities in the Aichi strain. Experiments showed that only enzyme NA(H-) of the Aichi strain was incorporated into the hybrid X-32 virus during genetic recombination.

Chromatography, Affinity↗
PubMed1980

The isolation and properties of a ribonuclease associated with influenza virus.

A ribonuclease activity associated with influenza virus has been purified to homogeneity. This preparation is free of DNAase, phosphodiesterase, and phosphatase activities. The purified enzyme has a pH optima of 7.0 at 37 degrees C, and moves as a single band on sodium dodecyl sulfate - polyacrylamide gel with an estimated molecular weight of 84 000.

Electrophoresis, Polyacrylamide Gel↗
PubMed1979

Influence of cold working on fatigue behavior of stainless steels used for prothesis: application to the study of wires with small sections.

Orthodontists mainly use stainless austenitic wires with a wide range of ultimate tensile strength. To characterize the dynamical behavior of these wires, the authors have perfected machines to test materials with their original surface roughness without any prior machining of surfaces. Fatigue limits are discussed through mechanical and structural properties of the austenitic steels, with special attention given to cold working. Typical features of fracture, and particularly of the first cracks, are shown by means of scanning electron microscopy.

Alloys↗
PubMedDate not supplied

Mineralocorticoid hormones exert dramatic effects on pluripotent human stem cell progeny.

The authors studied mineralocorticoid receptor (MCR)-mediated effects of steroids on CD34(+) progenitor cells. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed the presence of mRNA for both the MCR and the alpha subunit of the epithelial sodium channel, a member of the amiloride-sensitive sodium channel (ASSC) superfamily, in human CD41(+) megacaryoblastic cells derived from cultured bone marrow CD34(+) isolates, as well as in the human erythromegakaryoblastic leukemia (HEL) cell line. Immunofluorescence also revealed the presence of both the MCR and ASSC in circulating CD34(+) and medullar CD41(+) megacaryoblastic cells, the former as a nucleocytoplasmic protein and the latter as a membrane-bound protein, as expected from earlier studies using MCR-specific targets. In a selective medium, the formation of erythrocyte burst-forming units, and of the granulocyte-macrophage colony-forming units, by circulating CD34(+) cells was influenced by the agonists deoxycorticosterone and aldosterone, as well as by the antagonists RU 26752 and ZK 91587, targeted for the MCR. The multiplication of the leukemic HEL progeny, derived from CD41(+) cells, was similarly altered by these steroids targeted for the MCR. In contrast, in the optimal growth medium, the multiplication, and colony formation by bone marrow CD34(+) progenitor cells were not altered by either aldosterone or ZK 91587. These and other studies reveal that the receptor-mediated action of mineralocorticoids may influence the functional maturation of the hematopoietic progenitor lineage, contrary to the classical notion where the mineralotropic effect would be a unique feature of the epithelial cell.

Antigens, CD34↗
PubMedDate not supplied

Organizational support of the clinical nurse specialist role: a nursing research and professional development directorate.

Administrative support is essential for optimal utilization of the Clinical Nurse Specialist (CNS) resource. It has been linked to successful role implementation, role efficacy and job satisfaction. The article addresses how a Nursing Research and Professional Development Directorate (NRPD) provides administrative support of the CNS role. The impact of the directorate on the role functions of practitioner, consultant, educator and researcher is delineated. Specific challenges to the CNS role and organizational benefits are described. A model of organizational support of the CNS, based on the concepts of collaboration and peer mentorship, is proposed. The model emphasizes mutual goal setting to achieve both organizational and professional objectives.

Humans↗
PubMedDate not supplied

Primary drug resistance to Mycobacterium tuberculosis in renal transplant recipients.

BACKGROUND: After renal transplantation, patients have an up to 5% chance of being infected with Mycobacterium tuberculosis and there are reports from western countries of a 24% mortality if the infection is drug resistant. We investigated primary drug resistance in renal transplant recipients in Vellore, Tamil Nadu. METHODS: Between January 1987 and December 1993 we studied 695 patients (who had received 717 renal allografts) for evidence of tuberculosis, and performed drug sensitivity tests. RESULTS: Forty-three patients had culture-proven infection with Mycobacterium tuberculosis of whom 40 had drug sensitivity tests done. Initial drug resistance was seen from 1991. Rifampicin resistance was seen in 2, 1 and 4 patients and isoniazid resistance in 1, 2 and 2 patients in 1991, 1992 and 1993, respectively of the 23 isolates tested for drug susceptibility. Multi-drug resistance was seen in 1 and 2 patients in 1992 and 1993. CONCLUSIONS: This is probably the first report in India of primary drug resistance of Mycobacterium tuberculosis in renal allograft recipients. It is a cause for concern as it may indicate a large reservoir of drug-resistant patients in the community.

Antibiotics, Antitubercular↗
PubMedDate not supplied

A model for professional nursing in organizations: the Rainbow.

This paper presents a model of professional nursing in organizations that provides cohesive direction to the development of patterns that shape how nursing is structured in an organization. Such cohesive direction can foster integration between the practice and the discipline components of nursing. The model can influence the structure of nursing on a macro level within the organization and on a micro level by influencing patterns of nursing care delivery. A set of values, assumptions, dimensions, constructs, principles and propositions have been identified and brought together in this model. As a framework, it can be used to shape the structures and processes that contribute to professional nursing excellence in practice settings.

Health Knowledge, Attitudes, Practice↗