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Biomedical subjects

A Kent

Publications and source records attributed to A Kent.

At least 55 records · Page 3Linked to original sources
PubMed1995

Evidence for signalling by big endothelin-1 via conversion to endothelin-1 in pulmonary artery smooth muscle cells.

In this study, signalling by big endothelin-1 (big ET-1) and a role for the phosphoramidon-sensitive endothelin converting enzyme in this signalling was investigated in smooth muscle cells cultured from bovine pulmonary artery. In whole cells, both ET-1 and big ET-1 stimulated inositol phosphate accumulation in a time- and concentration-dependent manner. The endothelin ET-A receptor antagonist (BQ 123, 1 microM) significantly inhibited stimulation by ET-1 (10 nM) or big ET-1 (100 nM). When cells were pretreated with 100 microM phosphoramidon, the stimulation by big ET-1, but not ET-1 was abolished. In separate experiments, when cells were incubated with exogenous big ET-1, a time-dependent phosphoramidon-sensitive conversion to ET-1 was detected by radioimmunoassay. These results are consistent with the presence of a phosphoramidon-sensitive endothelin converting enzyme on the surface of bovine pulmonary artery smooth muscle cells, which may play a role in regulating signalling by circulating big ET-1.

Analysis of Variance↗
PubMed1995

Ovarian morphology and insulin sensitivity in women with bulimia nervosa.

OBJECTIVE: Hyperinsulinaemia has a role in the development of hyperandrogenism and polycystic ovary syndrome in women of normal weight. Polycystic ovaries are common in women with bulimia nervosa and this study aimed to determine whether women with bulimia nervosa are insulin resistant and to examine the relation between insulin sensitivity and ovarian morphology. DESIGN: A short intravenous insulin tolerance test was used as a direct measure of insulin sensitivity in a group of women with bulimia nervosa and a control group. PATIENTS: A series of 12 women with bulimia nervosa and normal weight was compared with a control group of 9 healthy women who had no clinical signs of eating disorder or hyperandrogenism and did not have polycystic ovaries. MEASUREMENTS: Bulimic behaviour was assessed using the BITE (Bulimia Investigation Test, Edinburgh) questionnaire and clinical interviews. Ovarian morphology was assessed using transabdominal ultrasonography. Insulin sensitivity and serum insulin, fasting glucose, LH, FSH, prolactin, testosterone, androstenedione and sex hormone binding globulin (SHBG) were measured and compared between the two groups. RESULTS: Ten of the 12 women with bulimia nervosa underwent ovarian ultrasound examination and they all had polycystic ovaries. There was no difference in serum LH, FSH, testosterone, androstenedione of SHBG concentrations between the women with bulimia nervosa and the non-bulimic control group. Fasting blood glucose concentrations were normal in all the women studied and did not differ between the women with bulimia nervosa and the control women. There was also no difference in fasting serum insulin or insulin sensitivity between the women with bulimia nervosa and the nonbulimic women. CONCLUSIONS: Bulimia nervosa is not associated with insulin resistance and chronic hyperinsulinaemia.

Adult↗
PubMed1994

The Schwann cell precursor and its fate: a study of cell death and differentiation during gliogenesis in rat embryonic nerves.

We have characterized a cell, the Schwann cell precursor, that represents a distinct intermediate differentiation stage in the process by which Schwann cells are generated from neural crest cells. The Schwann cell precursor shows radical differences from Schwann cells which include death regulation, antigenic phenotype, pattern of cell-cell interaction, migratory behavior, and morphology. In the nerves of the rat hind limb, Schwann cells are irreversibly generated from these during a brief period, essentially embryonic days 15-17. We also provide evidence that the survival of Schwann cell precursors is regulated by neurons and identify basic fibroblast growth factor as a potential key regulator of apoptosis in Schwann cell precursors and of precursor to Schwann cell conversion. These findings have implications for our understanding of gliogenesis in the peripheral nervous system.

Animals↗
PubMed1994

Assessing humanitarian needs--Afghanistan.

During 5 weeks of 1993, 10,000 people were wounded and over 800 killed in Kabul, capital city of Afghanistan. 50,000 refugees have fled Kabul for the countryside, or the safety of Pakistan. In the Bosnian conflict 55,000 people have been injured over the past 2 years. At the present rate, Kabul will reach this total within 6 months. My brief in Kabul was to visit as many hospitals and polyclinics as possible, talk to the staff, and find out whether there is a need for MERLIN (Medical Emergency Relief International) to intervene in this area. This intervention would be in the form of a short mission of 3-4 months duration, deploying a trauma team, immunisation programme or supplies facility. It was essential to assess the trauma facilities and document what supplies and staff were needed.

Afghanistan↗
PubMed1994

Characterization of membrane proteins exported from Plasmodium falciparum into the host erythrocyte.

Plasmodium falciparum is an intracellular parasite of the red blood cell. During development it exports proteins which are transported to specific locations within the host erythrocyte. We have begun to identify and characterize exported membrane proteins of P. falciparum in order to obtain specific marker molecules for the study of the mechanisms involved in the distribution of parasite-derived proteins within the host cell. In this report we describe the characterization of a 35 kDa protein which is recognized by a monoclonal antibody. The protein is tightly associated with membranes isolated from infected erythrocytes; it is resistant to extraction with alkali and soluble after treatment with detergents. It is located at the membrane of the parasitophorous vacuole and in membrane-bound compartments which appear in the cytoplasm of the infected erythrocyte. The protein co-localizes with the previously described exported protein-1 (exp-1). Considering its localization and physical similarities to exp-1, we name the 35 kDa protein the exported protein-2 (exp-2).

Animals↗
PubMed1993

Cellular morphology and extracellular space at rhombomere boundaries in the chick embryo hindbrain.

The chick embryo hindbrain is a segmented region of the CNS characterised by repeated blocks of neuroepithelial cells, known as rhombomeres. Individual rhombomeres are polyclonal compartments, defined both by cell lineage restriction and by the restricted expression of development control genes, that later acquire specific patterns of neuronal differentiation and axon outgrowth. The interfaces between adjacent rhombomeres are defined by boundaries across which cells do not move; the boundaries contain specialised cells and are preferentially colonised at early stages of development by extending axons. In this study, routine electron microscopy and high-pressure cryopreservation, a technique that avoids artifacts of chemical fixation, have been used to examine the morphology of rhombomere boundaries through a staged series of chick embryos. We find that the boundary regions contain enlarged extracellular spaces and that these form conduits for axons subsequently extending in the circumferential plane of the hindbrain. Labeling the ventricular surface of the neuroepithelium with DiI crystals in aqueous suspension revealed the morphology of individual cells in the intact neural tube, and demonstrated unusual fan-shaped arrays of cells at the boundaries. These findings contribute further to the evidence that cells at rhombomere boundaries differ from those in rhombomere centres, and leads to hypotheses about both the mechanism of development of the boundaries, and the role they may play in hindbrain patterning.

Animals↗
PubMed1993

Rehabilitation and staffing levels in a 'new look' hospital-hostel.

The present study examined the utility of a new hospital-hostel with low staffing levels. Results showed that the hostel was able to maintain 9 of the 10 initially transferred patients and has been able to provide some improvements in their quality of life. However, unlike highly staffed hospital-hostels, it was not able to decrease patients' disabilities. Implications of this are discussed in relation to staffing levels and practices.

Activities of Daily Living↗
PubMed1992

Pre-menarchal bulimia nervosa.

Although pre-pubertal anorexia nervosa has been well described, pre-pubertal bulimic behaviour in the context of this disorder appears to be uncommon. There have been no published reports of pre-pubertal bulimia nervosa occurring independently. Of 323 patients with bulimia nervosa attending an eating disorders research clinic between 1980 and 1989, the authors identified six patients who described pre-menarchal binge eating in the absence of a concurrent history of anorexia nervosa or massive obesity. Three (0.93%) of these patients described a pre-menarchal onset of bulimia nervosa, but there was no evidence that they were pre-pubertal. The implications of these findings are discussed.

Adolescent↗
PubMed1992

The ANF-C receptor is not linked to adenylyl cyclase inhibition in bovine pulmonary artery endothelial cells.

The possible inhibition of adenylyl cyclase activity by atrial peptides selective for the ANF-C receptor was investigated in bovine pulmonary artery endothelial cells. In these cells isoprenaline, guanine nucleotide and forskolin dose-dependently increased activity over basal levels. In the presence of rANF(99-126), these dose-dependent increases were not reduced, nor were they affected by the ANF-C receptor selective analogue C-ANF(102-121). Furthermore, the selective analogues rANF(103-123) and des[Cys105,Cys121]rANF104-126 had no effect on basal or stimulated adenylyl cyclase activity. It can be concluded that ANF-C receptors are not linked to inhibition of adenylyl cyclase in these cells.

Adenylyl Cyclase Inhibitors↗