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Biomedical subjects

K Thomas

Publications and source records attributed to K Thomas.

At least 163 records · Page 9Linked to original sources
PubMed1995

Angiotensin-II stimulates estradiol secretion from human placental explants through AT1 receptor activation.

A complete renin-angiotensin system has been shown to be present in human placenta, but its physiological role is poorly known. To investigate the implication of this system in the regulation of steroid hormone secretion, we studied the effect of angiotensin-II on the release of estradiol and progesterone from human placental explants. Our experiments showed that angiotensin-II stimulated estradiol secretion from term placental explants in a dose- and time-dependent fashion, although progesterone release was unaffected. Estradiol release induced by angiotensin-II (0.2 mumol/L) was blocked by angiotensin AT1 receptor antagonist losartan in a dose-dependent manner, suggesting the involvement of the AT1 receptor subtype in the process. On the contrary, the angiotensin AT2 receptor antagonist PD123319 (1 mumol/L) or the angiotensin AT2 receptor agonist CGP42112A (1 mumol/L) had no effect. Analysis of the amount of steroid hormones in the placental tissues incubated for 12 h showed that angiotensin-II increased estradiol production by 34% compared with the unstimulated explants, whereas the total levels of the estrogen precursor androstenedione and testosterone were decreased by 30-45% in the presence of the peptide, suggesting a stimulatory effect on the aromatization step. This hypothesis was reinforced by the absence of effect of angiotensin-II on both estradiol and testosterone concentrations in the placental explants pretreated with the aromatase inhibitor 4-hydroxyandrostenedione (25 mumol/L). Progesterone synthesis was not affected by angiotensin-II. The present study indicates that angiotensin-II induces the secretion of estradiol from human placenta through the angiotensin AT1 receptor subtype activation, and this effect seems to be linked to the stimulation of local androgen aromatization.

Angiotensin II↗
PubMed1995

Assessing the outcome of making it easier for patients to change general practitioner: practice characteristics associated with patient movements.

BACKGROUND: The government white paper, Promoting better health, suggested that primary health care services should be made more responsive to patient needs and that competition, brought about by the freer movement of patients between practices, could act as a mechanism for improving the quality of the services provided. Policy changes reflecting these aims were introduced with the 1990 contract for general practitioners. AIM: A study was carried out to estimate the volume of patient movement between practices not attributable to a patient's change of address or to a major change in the practice they had left, and to investigate which practice characteristics patients moved towards and which they moved away from when changing general practitioner. METHOD: Data on 2617 patient movements during June 1991 were collected from five family health services authorities. These patient movements were analysed in relation to data on practice characteristics obtained from family health services authority records. RESULTS: The estimated volume of movement of patients between practices was small (1.6% of the registered population per year). The majority of movements were between group practices; a quarter of the movements recorded were to single-handed general practitioners. However, the ratio of the number of movements from group practices to single-handed general practitioners compared with those from single-handed general practitioners to group practices was 1.37 (95% confidence interval 1.19 to 1.57). In choosing single-handed general practitioners these patients were willing to forgo access to a woman general practitioner, extended services and greater hours of general practitioner availability. Among the subset of movements between group practices, patients were more likely to gain access to a practice nurse, longer surgery hours and a woman general practitioner as a consequence of their move. CONCLUSION: The scale of patient movement observed did not indicate any substantial mechanism by which the new policy of encouraging consumerist behaviour on the part of primary care users could effect desired changes in primary care practice. Among the patient movements observed, the evidence suggests that when choosing a practice potential patients were not deterred by the fact that a practice was single-handed. The public's perception of the factors contributing to a high quality of service may conflict with the official characterization of good practice and high quality services in primary health care.

Adolescent↗
PubMed1995

[Consumption coagulopathy during pregnancy: a case of afibrinogenemia during the second trimester].

We report a case of a membrane disruption at 19 weeks 3 days of gestation complicated by a consumption coagulopathy with clotting tests suggesting primary fibrinogenolysis rather than a disseminated intravascular coagulation usually seen in such cases. A review of the literature revealed 5 cases of coagulopathy during the second trimester of pregnancy among which only two were suspected to be associated with primary fibrinogenolysis. Management of this coagulopathy is discussed.

Abruptio Placentae↗
PubMed1995

Incidence of intermediate syndrome in organophosphorous poisoning.

Seventy two patients admitted to the Intensive Care Unit following ingestion of organophosphorus compounds were studied prospectively with two different doses of pralidoxime (PAM). One group received 1 gm immediately after admission and no further PAM and the other group received infusion of PAM, 1 gm 8 hourly for four days (total 12 gms). The incidence of type II paralysis or intermediate syndrome was 47%. We observed a higher incidence in the 4 days of infusion of PAM group (61%) (20 patients) as compared to the single Bolus dose group (39%) (13 patients). Relative risk 1.48 (confidence interval = 0.9-2.4).

Adult↗
PubMed1994

Down regulation of the angiotensin II receptor subtype AT2 in human myometrium during pregnancy.

Samples of human myometrium have been collected during pregnancy and from non-pregnant women. Binding studies revealed the presence of a 50-fold higher density of angiotensin II AT2 receptor in the non-pregnant state than during gestation. Low levels of the AT1 receptor subtype (approx. 20 fmol/mg protein) were detected in both pregnant and non-pregnant myometrium. Outside pregnancy, the AT2 receptor accounted for greater than 95% of all angiotensin receptors, whereas during pregnancy the value dropped to about 40%. The down regulation of the human myometrial AT2 receptor during pregnancy may be related to the high hormonal content of the environment induced by gestation. The mechanism by which the AT2 receptor is regulated appears to be different to that of the AT1 receptor.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1994

Angiotensin II induces human placental lactogen and pregnancy-specific beta 1-glycoprotein secretion via an angiotensin AT1 receptor.

The purpose of this work was to determine which subtype of angiotensin II receptors was involved in angiotensin II-induced human placental lactogen (hPL) and pregnancy-specific beta 1-glycoprotein (SP1) secretion from human placenta. The experiments were performed using placental explants and isolated trophoblast cells. They were pretreated with Dup753 (antagonist of angiotensin AT1 receptor), PD123319 (antagonist of AT2 subtype) or with CGP42112A (agonist of angiotensin AT2 receptor) before the addition of angiotensin II. The octapeptide angiotensin II significantly increased the hPL and SP1 release from both placental explants and isolated trophoblast cells. The angiotensin AT1 receptor antagonist Dup753 inhibited the angiotensin II-stimulated hPL and SP1 secretion in a dose-dependent manner but the AT2 specific ligands PD123319 and CGP42112A had no effect. This study indicates that the angiotensin AT1 receptor is the main mediator of angiotensin II in the stimulation of hPL and SP1 secretion from human placenta.

Angiotensin II↗
PubMed1994

60 Hertz magnetic field exposure assessment for an investigation of leukemia in telephone lineworkers.

The purpose of this paper is to present the assessment of magnetic field exposure conducted as a part of a nested case-control investigation of leukemia mortality in telephone lineworkers. For the purposes of exposure classification, telephone company jobs were initially divided into two classes: those with potential for working in an electric environment, referred to as linework jobs, and those not working in an electric environment, referred to as nonlinework jobs. Linework jobs were further divided into the following four categories: outside plant technicians (OPT), installation/maintenance/repair (IMR) technicians, central office technicians (COT), and cable splicing technicians (CST). These job groupings were based on similarity of work tasks and exposure environments. Emdex data-logging dosimeters were used to measure personal exposures to ELF magnetic fields for 204 telephone company workers. Three general classes of exposure indices were calculated for each exposure record: measures of central tendency, measures of peak or maximum exposure, and measures of exposure variability. CSTs had the highest full-shift mean and median exposure, 4.3 and 3.2 mG, respectively. CSTs also ranked the highest, with average peak, average 95th percentile, and average time above background equal to 99.2 mG, 11.1 mG, and 156 min, respectively. In addition, the results suggest the OPT and IMR technicians have exposures similar to nonlineworkers. Exposure classifications, therefore, which misclassify all lineworkers into one "telephone lineworker" job grouping are not appropriate and future studies should concentrate on cable splicing technicians.

Case-Control Studies↗
PubMed1994

Isolation of cosmid and cDNA clones in the region surrounding the BTK gene at Xq21.3-q22.

A regional physical and transcription map involving yeast artificial chromosomes (YACs), cosmids, and cDNAs has been constructed for Xq21.3-q22 around the gene BTK (formerly atk or BPK) defective in X-linked agammaglobulinemia (XLA). With a positional cloning strategy employing direct cDNA selection, novel cDNAs were found to cluster in the region of approximately 100 kb flanking the XLA and alpha-galactosidase A loci. While these widely expressed transcripts are in the area known to contain CpG islands, a less evolutionarily conserved gene, located more than 130 kb distal of DXS178, maps to cosmid clones that could not be digested with rare-cutting restriction enzymes. The presence of transcribed sequences flanking the BTK allowed us to investigate their involvement in complex XLA phenotypes. Southern blot analysis using cDNA clones isolated from this region permitted us to exclude a contiguous deletion syndrome as an underlying defect in three patients with XLA and associated growth hormone deficiency. A single XLA patient with torsion dystonia and cosegregating X-linked deafness has been found with a deletion in the 3' part of BTK extending centromerically into the flanking expressed sequence DXS1274E. This suggests a possible involvement of the DXS1274E in this phenotype. The GenBank accession numbers for novel cDNA sequences are as follows: DXS1269E (L20773), DXS1271E (UO1923), DXS1273E (UO1925), and DXS1274E (UO1922).

Agammaglobulinaemia Tyrosine Kinase↗
PubMed1994

Utilization of a time-limited holiday hotline by older adults.

Lonely older adults are frequently hesitant to reach out for help because they fear forced institutionalization or other loss of control over their lives. The utilization of a time-limited holiday hotline for outreach to lonely older persons is examined. There were 306 calls from aged persons. Grief and bereavement were the primary themes of these calls. Trained professionals and supervised students staffed the telephone bank and provided such services as responsive listening and community referrals.

Aged↗
PubMed1994

Intestinal mucosal immunoglobulins during human immunodeficiency virus type 1 infection.

In intestinal fluid samples from 39 human immunodeficiency virus type 1 (HIV-1)-infected patients, IgA and IgG levels were equivalent, whereas in 10 controls, IgA levels were significantly higher than those of IgG (P < .05). Intestinal IgA in patients contained predominantly monomeric IgA1, whereas IgA1 and IgA2 subclass levels in controls were nearly equivalent and primarily polymeric. The predominance of IgG and monomeric IgA1 in mucosal fluid samples from HIV-1-infected patients suggests exudation of serum immunoglobulins into the intestine. The decreased proportion of mucosal plasma cells producing IgA and IgA2 in the HIV-1-infected patients (P < .01) may also contribute to the abnormal intestinal immunoglobulin levels. Intestinal IgG reacted with most HIV-1 antigens, whereas specific IgA was present in only 10 of 17 patients and reacted with only envelope (gp120 and gp160) and, less often, core (p17 and p24) antigens. Aberrant mucosal antibody responses and decreased integrity of the mucosal barrier may contribute to the intestinal dysfunction and infections that characterize HIV-1 infection.

Diarrhea↗
PubMed1994

The probability of a successful treatment of infertility by in-vitro fertilization.

The objective of this study was to define several estimates of the success rate of in-vitro fertilization and embryo transfer treatment in relation to treatment outcome. The data were collected in a retrospective study of 591 patients treated during 3 years in one Belgian university hospital. Several models used for evaluating the treatment of infertility were fitted to the data (logistic model, binomial model, double binomial model, exponential model, the Speirs model. The number of oocytes retrieved and the proportion of fertilized oocytes at the first attempt can be used as prognostic factors. According to these factors, the success rate after five attempts varies from 28 to 88%.

Belgium↗