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Biomedical subjects

K Thompson

Publications and source records attributed to K Thompson.

At least 91 records · Page 5Linked to original sources
PubMed1995

Effects of short-term cortisol infusion on growth hormone-releasing hormone stimulation of growth hormone release in sheep.

Excess production or long-term administration of glucocorticoids is detrimental to longitudinal growth in people and rats. A portion of this effect is attributed to cortisol inhibition of growth hormone (GH). Glucocorticoid effects are usually studied in subjects under long-term treatment with synthetic, more potent glucocorticoids, and, to the authors' knowledge, have not been examined in domestic animals. We sought to examine the effects of cortisol infusion on GH release in sheep. Cortisol infusion into castrated, male Suffolk sheep (1 to 1.5 years old) caused a significant (P < 0.0001) increase in cortisol concentration. Basal GH release was not affected over the 4-hour period of infusion. Growth hormone-releasing hormone administration stimulated GH release in both groups (P < 0.001); however, the control group had a greater response to growth hormone-releasing hormone than did the cortisol infused group (P < 0.0001). These results were duplicated in cultured sheep pituitary cells. Cortisol inhibition of GH release may be mediated via enhanced somatostatin release, owing to a direct inhibition of somatotrope function, or a combination of both mechanisms. Because of effects of stress and disease in increasing cortisol concentration, additional study of the mechanisms for cortisol inhibition of GH release in sheep needs to be performed.

Analysis of Variance↗
PubMed1995

Effectiveness of a dot-blot immunoassay of anti-Rickettsia tsutsugamushi antibodies for serologic analysis of scrub typhus.

We compared a commercially available dot-blot immunoassay system with the indirect immunofluorescence assay (IFA) in tests of known negative and known positive sera from scrub typhus cases. Using a panel of 100 sera from patients with various rickettsial and nonrickettsial infections, we observed that the IFA was 99% specific and the dipstick assay was 98% specific. In tests of 91 sera (30 negative and 61 positive for scrub typhus antibodies) from a study of febrile patients in Malaysia, using the standard of an IFA titer < 1:64 as negative, an IFA titer > 1:128 as positive, and an IFA titer = 1:64 as either positive or negative (supported by clinical records), dipsticks were 83% specific and 90% sensitive. The quantitative correlation of the dipsticks to IFA titers was confirmed by significant differences in geometric means of inverse IFA titers corresponding to the number of positive dipstick spots (no dots = 8.5, one dot = 43.3, two dots = 206.7, and three dots = 676.9). The assay would enable physicians and public health workers who deal with patients to quickly diagnose and appropriately treat most cases of the disease, especially in areas of high prevalence where the proportion of false-positive results to true-positive results would be low.

Antibodies, Bacterial↗
PubMed1994

Production, purification, and characterization of human matrilysin (PUMP) from recombinant Chinese hamster ovary cells.

A process for semicontinuous production of matrilysin zymogen secreted from recombinant Chinese hamster ovary (CHO) cells was developed. The zymogen was purified to apparent homogeneity by sequential ion-exchange and metal chelation chromatography. These processes were scaled-up to purify gram quantities of the zymogen. The N-terminus of the secreted zymogen from the recombinant cells was the same as the observed sequence of the zymogen from natural sources. Furthermore, activation and autocatalysis of the recombinant zymogen resulted in a form with an N-terminus identical to that of the corresponding native enzyme. The three C-terminal amino acids of both the recombinant zymogen and the corresponding smaller activated form were missing. Activated matrilysin was shown to have activity against a synthetic peptide substrate. The large quantities of matrilysin that can be produced and purified from the recombinant CHO cells will be useful in determination of the structure of matrilysin.

Amino Acid Sequence↗
PubMed1994

Plasmid labeling confirms bacterial translocation in pancreatitis.

To examine whether the gut is a source of infection in acute pancreatitis, bacterial translocation and alterations of intestinal microecology and morphology were studied in 16 dogs. Dogs were colonized with a strain of Escherichia coli (E. coli 6938K) bearing the plasmid pUC4K, which confers kanamycin resistance. In eight dogs (group I), pancreatitis was induced by sodium taurocholate/trypsin injection. Eight other dogs (group II) underwent laparotomy only. The pancreas, mesenteric lymph nodes, peritoneal fluid, liver, and spleen were harvested 7 days later for culturing and histologic analysis. Identification of E. coli 6938K was accomplished by plasmid DNA analysis. Group I dogs had severe pancreatitis and ischemic changes in small bowel mucosa. Group II dogs had no changes. Translocation to the pancreas occurred in five dogs and to mesenteric lymph nodes in six dogs with pancreatitis. No translocation occurred in group II dogs (p < 0.05). In addition to E. coli 6938K, other gram-negative kanamycin-resistant species were isolated, including E. coli (other than 6938K) and Enterobacter cloacae. Enteric origin of these strains was confirmed by antibiography and plasmid DNA analysis. No overgrowth of cecal gram-negative bacteria was found. This study suggests that the gut is a primary source of infection in pancreatitis and that ischemic damage of intestinal mucosa may promote bacterial translocation.

Acute Disease↗
PubMed1994

An evaluation of the adequacy of health visitor education for neonatal hip screening.

Congenital dislocation of the hip (CDH) affects two children per 1000, with potentially serious consequences. Student health visitors in Northern Ireland learn screening techniques for CDH at a half-day workshop at a regional hospital. In order to evaluate the adequacy of this preparation, 71 qualified health visitors were surveyed to assess their knowledge relating to CDH, their views on the adequacy of the training, and their opinions about referral of positive cases. Knowledge in some areas was poor and preparation was considered too short. Direct referrals of positive cases to orthopaedic clinics, without a general practitioner acting as an intermediary, was a frequently cited desire. Recommendations include extending the training for those involved in CDH screening while ensuring that experienced health visitors, from whom novices learn, are themselves using correct procedures.

Attitude of Health Personnel↗
PubMed1994

Analysis of circulating phagocyte activity measured by whole blood luminescence: correlations with clinical status.

The present study was undertaken to determine if measurement and analysis of phagocyte function are useful for diagnosis and staging of infection. Circulating phagocyte activity was measured in healthy volunteers and sequentially in patients with acute infections of different types and severity, including those with diabetes mellitus or human immunodeficiency virus (HIV) infection. Using an automated luminescence system, these phagocyte functions were measured in whole blood: basal and phorbol 12-myristate 13-acetate (PMA)-stimulated oxidase activity, basal and PMA-stimulated simple dioxygenation (e.g., oxidase-driven haloperoxidase activity), and circulating and primed opsonin receptor-dependent dioxygenation. Multiple discriminant analysis of these data showed significant differences between healthy controls, diabetic patients, HIV-positive subjects, and patients with pneumonia or sepsis syndromes. Longitudinally, circulating phagocyte function correlated with clinical condition, severity of infection, and outcome. This methodology provides rapid, objective, and sensitive diagnostic and monitoring information for patients with infections.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Student midwives' learning experience on the wards.

This paper is based on an investigation into the learning experiences of student midwives in the clinical setting in one maternity unit in the Republic of Ireland. A questionnaire approach was adopted for the data collection and 42 student midwives participated in the study. A number of factors were identified which appear to influence students' experiences of 'learning on the job'. The quality of their clinical teaching and their observations of the way in which trained staff practise midwifery may influence their decision to continue practising midwifery following registration. These findings clearly point to the importance for midwives to reassert their true role as 'independent practitioners' of normal maternity care.

Adult↗
PubMed1993

Mapping studies reveal unique epitopes on IgG recognized by rheumatoid arthritis-derived monoclonal rheumatoid factors.

We have used chimeric IgG antibodies and their genetically engineered variants prepared by a combination of site-directed mutagenesis and exon exchange to define the structure(s) on IgG recognized by monoclonal rheumatoid factor (RF) autoantibodies from rheumatoid arthritis (RA) patients. Nineteen RF produced by EBV-transformed cell lines from the synovium or blood of RA patients were analyzed. Their binding patterns differ significantly from those seen with RF obtained from patients with Waldenstrom's macroglobulinemia (WMac). Half of the RA-derived RF bound IgG1, 2, and 4, but not 3 (Ga specificity), the common pattern in WMac. However, heterogeneity in fine specificity within the Ga reactivity pattern was observed. Moreover, seven others bound all four IgG subclasses, a pattern observed for only one WMac-derived RF from a patient who also had RA. Three RF had subclass specificities unlike any observed with WMac-derived RF. Most RA-derived RF bound IgG at a discontinuous epitope comprised of residues from both the CH2 and CH3 H chain constant regions. However, unlike any WMac-derived RF, one RA-derived RF bound IgG in CH2, another in CH3, and a third at an undetermined site outside of the CH2-CH3 interface. Some RA-derived RF bound aglycosylated IgG4 less well than glycosylated IgG4, suggesting that the carbohydrate moiety was important in establishing their binding epitope in CH2. These studies demonstrate that the repertoire of RF expressed by RA patients contains some unique binding specificities for IgG epitopes not found among our panel of WMac-derived RF. Our results therefore call into question whether WMac-derived RF with their limited diversity are appropriate models for disease-related RF. In addition, RF with their multiple specificities can serve as probes of antibody structure.

Animals↗
PubMed1993

Wavelengths effective in induction of malignant melanoma.

It is generally agreed that sunlight exposure is one of the etiologic agents in malignant melanoma of fair-skinned individuals. However, the wavelengths responsible for tumorigenesis are not known, although DNA is assumed to be the target because individuals defective in the repair of UV damage to DNA are several thousandfold more prone to the disease than the average population. Heavily pigmented backcross hybrids of the genus Xiphophorus (platyfish and swordtails) are very sensitive to melanoma induction by single exposures to UV. We irradiated groups of five 6-day-old fish with narrow wavelength bands at 302, 313, 365, 405, and 436 nm and scored the irradiated animals for melanomas 4 months later. We used several exposures at each wavelength to obtain estimates of the sensitivity for melanoma induction as a function of exposure and wavelength. The action spectrum (sensitivity per incident photon as a function of wavelength) for melanoma induction shows appreciable sensitivity at 365, 405, and probably 436 nm, suggesting that wavelengths not absorbed directly in DNA are effective in induction. We interpret the results as indicating that light energy absorbed in melanin is effective in inducing melanomas in this animal model and that, in natural sunlight, 90-95% of melanoma induction may be attributed to wavelengths > 320 nm--the UV-A and visible spectral regions.

Animals↗
PubMed1993

Self-governed health.

As primary caregivers in remote Indian communities in northern Canada, nurses often witness considerable health status inequities between these people and the rest of Canada's population. In Saskatchewan, for example, tuberculosis incidence rates are 15 times higher for northerners in general than for people in the south. Infant mortality rates are twice as high, suicides are three times higher, motor vehicle related deaths are four to six times higher and deaths from diabetes in Indians aged 45 to 65 years are six times higher than in the general population. Some people suggest that these discrepancies are due simply to the inadequate funding of health care programs. Others refer to the remoteness of the communities and hence the inability to access advanced medical technology. A final hypothesis is that the increased exposure to white communities, practices and morals and the neglect of spiritual values have led to social disintegration and have hindered good health care practices.

Acculturation↗
PubMed1993

Gender differences in AIDS-relevant condom attitudes and condom use.

Two studies, conducted approximately one year apart, examined gender differences in AIDS-relevant condom attitudes, condom use behaviors, and relationships among attitudes and condom use behaviors. Subjects (N = 248, N = 528) were undergraduates, primarily heterosexual. Females reported more favorable attitudes, with the exception of greater inhibition about buying and possessing condoms. Men engaged in preliminary condom use behaviors (carrying and keeping condoms at home) substantially more often than did women. Preliminary condom use behaviors predicted past and intended condom use more consistently for men than for women. Relationships between condom attitudes and condom use behaviors were generally similar for both sexes, with poorer self-control explaining the most variance in past and intended condom use. These results, interpreted from the perspective of Eagly's (1987) gender role theory, suggest that although females may indirectly influence condom use decisions, providing condoms is the expected role of males, infusing them with greater control over the interpersonal process.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Heparin releasable and nonreleasable forms of heparan sulfate proteoglycan are found on the surfaces of cultured porcine aortic endothelial cells.

Evidence suggests that endothelial cell layer heparan sulfate proteoglycans include a variety of different sized molecules which most likely contain different protein cores. In the present report, approximately half of endothelial cell surface associated heparan sulfate proteoglycan is shown to be releasable with soluble heparin. The remaining cell surface heparan sulfate proteoglycan, as well as extracellular matrix heparan sulfate proteoglycan, cannot be removed from the cells with heparin. The heparin nonreleasable cell surface proteoglycan can be released by membrane disrupting agents and is able to intercalate into liposomes. When the heparin releasable and nonreleasable cell surface heparan sulfate proteoglycans are compared, differences in proteoglycan size are also evident. Furthermore, the intact heparin releasable heparan sulfate proteoglycan is closer in size to proteoglycans isolated from the extracellular matrix and from growth medium than to that which is heparin nonreleasable. These data indicate that cultured porcine aortic endothelial cells contain at least two distinct types of cell surface heparan sulfate proteoglycans, one of which appears to be associated with the cells through its glycosaminoglycan chains. The other (which is more tightly associated) is probably linked via a membrane intercalated protein core.

Animals↗
PubMed1992

Selective effects of triazolam on memory.

The effects of benzodiazepine (triazolam 0.25 and 0.50 mg) on different aspects of cognitive function were assessed. Triazolam impaired free recall and recognition of information presented after drug administration. In contrast to these impairments in explicit memory, a memory function that did not require conscious awareness was not altered by triazolam. Similarly, triazolam did not affect subjects' abilities to access semantic memory.

Adult↗