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Biomedical subjects

K Morgan

Publications and source records attributed to K Morgan.

At least 289 records · Page 16Linked to original sources
PubMed1987

Interviewing the elderly about their health: validity and effects on family doctor contacts.

Health-related questions in a large interview schedule (designed to examine relationships between customary physical activity, physical and psychological well-being among the elderly) were found to be repeatable (overall agreement was 93%) when used by two independent interviewers. The sensitivity and specificity of the interview in discriminating between people with and without health problems were 80% and 92%, respectively, when compared with a physician's independent assessments. Family doctor case notes under-recorded many of the common health problems of elderly people and could not be used to validate the interviewees' responses. Comparisons between 41 interviewees and 75 age-, sex- and practice-matched controls demonstrated that interviewees were only slightly more likely to consult or request a repeat prescription in the week following the interview (19%) than controls (11%). The 95% confidence intervals of this 8% difference were wide (-6% to 22%) and it might well have occurred by chance. Practices intending to use screening or research interviews with elderly people should be reassured such activities are not associated with large increases in demand for their services.

Aged↗
PubMed1987

Detection of renin messenger RNA in rat tissues: increased sensitivity using an RNAse protection technique.

Total cellular RNA and poly A+ RNA isolated from various tissues of Wistar-Kyoto (WKY) rats were screened for renin-specific messenger RNA by Northern blotting and RNAse protection. Northern blot analysis, carried out with a copy DNA (cDNA) probe of mouse submandibular gland renin, demonstrated a single RNA species of 1.8 kb in the kidneys of WKY rats. Other tissues screened by this technique were negative. With the more sensitive RNAse protection technique, our initial results indicate more widespread expression of renin, messenger RNA (mRNA) being detected in aorta, adrenal, heart, lung and spleen.

Adrenal Glands↗
PubMed1987

Paradoxic vocal cord syndrome with surgical cure.

Paradoxic vocal cord motion (PVCM) can cause wheezing, stridor, weak or absent voice, and ineffective cough. We have described a patient who had a posterior fossa arachnoid cyst, which was thought to be causing PVCM by compressing the brain stem. The PVCM and all symptoms resolved after surgical treatment of the arachnoid cyst.

Brain Diseases↗
PubMed1987

Incidence of antibodies to native and denatured cartilage collagens (types II, IX, and XI) and to type I collagen in rheumatoid arthritis.

The frequencies of antibodies to the cartilage type IX and XI collagens and to type I collagen were determined in 188 patients with rheumatoid arthritis, of whom 76 were positive for antibodies to native type II collagen. A higher proportion of patients with antibodies to native type II collagen had antibodies to these other collagens, but about one third of patients without antibodies to native type II collagen had antibodies to one or more denatured collagens. The patterns of antibodies present in individual sera suggested that there was a selective response to the collagens in an individual patient. The incidence of patients having antibodies to these native and denatured collagens in a random group of patients with rheumatoid arthritis was calculated.

Antibodies↗
PubMed1987

Problems and pitfalls in the isolation of an endogenous Na+, K+-ATPase inhibitor.

Plasma from volume-expanded and salt-loaded hypertensive animals and from patients with essential hypertension has been reported to inhibit Na+, K+-adenosine triphosphatase (ATPase). Inhibition of the sodium pump in vascular smooth muscle caused by such a circulating factor could increase vascular tone and sensitivity to vasoactive agents, and thereby result in arterial hypertension. Numerous efforts in the past failed to isolate the putative factor from urine and plasma. Recent studies have suggested that the hypothalamus is an important source of an endogenous Na+, K+-ATPase inhibitor, but its isolation from the tissue extracts has been rendered difficult by the presence of other cellular constituents that cause artifactual interference with the assays and purification procedures. Using an alternative approach of isolating the inhibitor from culture medium, we found that dispersed fetal rat hypothalamic neurons in a capillary culture system release a heat-stable, peptidic, low-molecular-weight, active sodium transport inhibitor that causes a reversible increase in vascular tone, sensitizes vascular smooth muscle to the vasoactive effect of norepinephrine, and possesses several characteristics of the putative endogenous digitalislike factor. This inhibitor may be a chemical mediator linking kidney, brain, and cardiovascular system in the genesis of experimental volume-expanded and salt-loaded hypertension and human essential hypertension.

Animals↗
PubMed1987

Mental health and psychological well-being among the old and the very old living at home.

Using four brief assessment scales, profiles of mental health and psychological well-being were obtained from 507 old (aged 65-74 years) and 535 very old (aged 75+) individuals randomly sampled from the community. Assessments of dementia and depression were subsequently validated against diagnostic ratings made by experienced psychogeriatricians. Levels of agreement between psychometric and clinical ratings of dementia (kappa = 0.83) and depression (kappa = 0.66) were satisfactory. The old and very old groups reported similar levels of anxiety and personal disturbance, and showed a similar prevalence of depression. However, those aged 75+ showed higher levels of dementia and significantly lower levels of social involvement and morale.

Aged↗
PubMed1987

Autosomal recessive juvenile cataract in Hutterites.

Autosomal recessive inheritance of juvenile cataract is described amongst several related sibships of Lehrerleut Hutterites. The main features of the cataract include onset between three and seven years of age; rapid progression to maturity within one to three months; normal intelligence; no systemic associations, and no urinary reducing substances and normal erythrocyte galactokinase activity. Genetic analysis demonstrates the close relationship between parents of affected sibships with a coefficient of inbreeding of affected sibships of 0.0512. Estimates of heterozygote frequency within Lehrerleut Hutterites at 0.128 indicate that if current inbreeding practice continues additional cases can be expected.

Alberta↗
PubMed1986

Serum stimulation of sodium transport in human fibroblasts containing low and high levels of intracellular sodium.

The relationships between intracellular sodium content, sodium transport and serum effects were investigated in human fibroblasts. In the cells with low intracellular sodium (Na+iL; 0.04 mumol sodium/mg protein), serum stimulated the sodium-potassium pump as measured by ouabain-sensitive sodium efflux and rubidium influx and also exerted a transstimulation of ouabain-insensitive sodium transport resulting in net influx. In cells with high intracellular sodium (Na+iH; 0.42 mumol sodium/mg protein) all aspects of sodium transport were increased compared to Na+iL cells. In these cells serum caused no change in sodium-potassium pump activity but significantly increased the ouabain-insensitive sodium fluxes resulting in net efflux. In Na+iL cells, serum promoted net sodium influx through an amiloride-sensitive pathway that was undetectable in the basal state. In Na+iH cells the serum-stimulated net efflux was amiloride sensitive but this pathway also contributed to a major portion of sodium transport in the basal state. This study demonstrated that sodium-potassium pump activity is directed by the supply of internal sodium and that serum can increase this supply by promoting net influx, and that serum-induced sodium transport can be modified by intracellular sodium content.

Animals↗
PubMed1986

Epilepsy and handicap from birth to age 36.

Fifty-five subjects with epilepsy were identified in the first 36 years of the 1946 birth cohort study. In 37 cases there was neither evident cause for the epilepsy nor associated brain-damage and these are referred to as 'uncomplicated', the rest as 'complicated'. Subjects with epilepsy came from poorer social backgrounds than the rest of the cohort. Mortality for both the complicated and uncomplicated groups was high. The educational and occupational achievements, marriage and parenthood, self-esteem and psychiatric morbidity of those surviving to adult life were compared with individually matched controls drawn from the same population. For the uncomplicated group there was no evidence of handicap at age 26, but 10 years later handicap was evident in this group in the economic sphere and in self-esteem.

Adult↗
PubMed1986

Inhibitin: a specific inhibitor of sodium/sodium exchange in erythrocytes.

An inhibitor of ouabain-insensitive sodium/sodium exchange in erythrocytes has been isolated from leukemic promyelocytes. To explore the specific effects of this inhibitor, named inhibitin, sodium transport experiments were carried out in human erythrocytes. Inhibitin reduced ouabain-insensitive bidirectional sodium transport. It did not change net sodium fluxes, had no significant effect on rubidium influx, and did not inhibit sodium-potassium-ATPase activity. The inhibitory effect of inhibitin was studied on sodium/sodium exchange and on sodium/lithium countertransport in 140 mM sodium and in sodium-free media. In the presence of sodium, inhibitin reduced sodium and lithium efflux to that observed in sodium-free medium. Inhibitin showed no reduction in sodium or lithium efflux when sodium was replaced by choline chloride or Mg2+. When inhibitin was combined with one or more of the other transport inhibitors (i.e., ouabain, furosemide, or bumetanide and amiloride), its inhibitable component remained distinct and it did not overlap with that of the other inhibitors. These studies show that inhibitin is a specific inhibitor of carrier-mediated sodium/sodium exchange and sodium/lithium countertransport processes in human erythrocytes.

Cell Line↗
PubMed1986

Segregation of HLA A,B haplotypes and the distribution of antigen mismatches between mother and offspring in Hutterite families.

Segregation of HLA haplotypes and offspring genotype distributions were analyzed in families from an inbred Caucasoid population, the Dariusleut Hutterite Brethren. Both parents and from one to 12 offspring were typed for HLA-A and -B antigens in 108 families. Segregation of paternal haplotypes was analyzed conditional on sibship size in 95 sibships (a total of 547 offspring), and segregation of maternal haplotypes, in 90 sibships (a total of 515 offspring). The distribution of the number of different genotypes among the offspring was analyzed conditional on sibship size in 90 families (515 offspring) where four equiprobable genotypes were expected. The distribution of the number of antigenic differences or mismatches for broad specificities between mother and offspring was analyzed in pooled family data consisting of a total of 377 offspring comprising 68 families. Compared with the multinomial distribution of segregation classes of haplotypes, there was no significant departure (probability .05 or less) from the expected segregation ratio for either paternal or maternal haplotypes. Compared with the multinomial distribution of the number of genotypes among the offspring, only two of the 11 sibship sizes had configurations that exceeded the 5% level of significance. Given the number of statistical tests performed, it is likely that these results could be explained by chance variation. Finally, there was no relative deficiency of offspring who were less mismatched with their mother for HLA-A and -B broad specificities. Therefore, if HLA-A,B region variation does have a major effect on the differential survival of fetuses in some families, it is an uncommon factor among fertile couples from this inbred population.

Alberta↗
PubMed1986

Release of a sodium transport inhibitor (inhibitin) from cultured human cancer cells.

In this study we investigated whether the sodium transport inhibitor, inhibitin, originally isolated from leukemic promyelocytes, was also elaborated by some other neoplastic cells in culture. Like culture medium from the leukemic promyelocytes (HL60), the media from two other leukemic cell lines (erythroblasts K562 and monoblasts U937) also showed significant inhibitory activity on ouabain-insensitive sodium efflux rate constant in normal erythrocytes. Similarly, culture media from three neoplastic cell lines (H.Ep2, MRC5, and HX99) also showed significant inhibitin-like inhibitory activity. Using high-performance liquid chromatography to isolate inhibitin, culture media from HL60 and H.Ep2 cells were identically treated, and inhibitin isolated from H.Ep2 cells had the same retention time as that shown by promyelocyte inhibitin. H.Ep2 inhibitin reduced ouabain- and bumetanide-insensitive sodium efflux rate constant from 0.1510 +/- 0.0275 (SD) to 0.0988 +/- 0.0110 (P less than 0.005). Like promyelocyte inhibitin, H.Ep2 inhibitin reduced sodium efflux and influx by equivalent amounts suggesting thereby that it is a sodium/sodium exchange inhibitor. These studies show that a factor exhibiting inhibitory activity on sodium/sodium exchange is secreted by a variety of leukemic and neoplastic cells in culture.

Biological Transport, Active↗
PubMed1985

A reproducible procedure for measuring sodium transport in cultured human fibroblasts from normal and obese donors.

Studies on erythrocyte sodium pump activity in obesity have yielded conflicting results probably because the erythrocyte is an atypical cell, and it may not reflect ATPase activity of other cells in the body. This study was undertaken to establish a reproducible procedure to measure sodium transport in human diploid fibroblasts, and apply this method to explore any differences in the cells from obese and nonobese humans. Cell cultures were established from 12 nonobese (body mass index (BMI) = wt in kg/height in m2 (Khosla and Lowe, Br J Prev Soc Med 1967; 21: 122-128); less than 27 kg/m2) and 10 obese (BMI) greater than 35 kg/m2) subjects. Triplicate measurements of sodium efflux rate constant were made with and without ouabain (1 mmol/l) to determine the total, active (ouabain-sensitive) and passive (ouabain-insensitive) components. Reproducible results were obtained as suggested by a coefficient of variation (CV) of less 10% on successive experiments on the same cell-line, and 11 and 15% of the active sodium efflux rate constant measured in fibroblasts from nonobese and obese subjects, respectively. The active sodium efflux rate constant in fibroblasts from nonobese (0.202 +/- 0.023 (SD)) was not significantly different from that obtained in the cells from obese subjects (0.21 +/- 0.030; p greater than 0.10). These results suggest that there is no intrinsic differences in basal sodium pump activity in fibroblasts related to obesity.

Biological Transport↗
PubMed1985

Characterization and partial purification of the sodium-potassium-ATPase inhibitor released from cultured rat hypothalamic cells.

An inhibitor of sodium-potassium-ATPase has been partially purified from the culture medium obtained from hypothalamic cells maintained in a capillary membrane perfusion system, and some of the properties of this inhibitory factor have been investigated. Gel filtration (Sephadex G-25 Superfine) of heat-treated medium (80 degrees C for 10 min) resulted in elution of inhibitory activity in the post-salt fraction. These fractions inhibited active (i.e. sodium-potassium-ATPase-mediated) sodium transport in intact human erythrocytes, displaced [3H]ouabain from its binding site, and directly inhibited canine kidney sodium-potassium-ATPase as measured by NADH oxidation. High-performance liquid chromatography (on Hypersil ODS) of these fractions after desalting yielded one region which showed inhibitory activity on all three assays. Inhibition of sodium-potassium-ATPase was dose-related and filtered through an Amicon UM10 membrane. Incubation of this material with dispase, carboxypeptidase A, chymotrypsin, and prolidase destroyed inhibitory activity, whereas trypsin and leucine aminopeptidase were ineffective. These studies show that hypothalamic neurones release a low molecular weight heat-stable peptide which inhibits active sodium transport, ouabain binding, and sodium-potassium-ATPase.

Animals↗
PubMed1985

Morquio syndrome (MPS IVA) and hypophosphatasia in a Hutterite kindred.

A patient is described who has Morquio syndrome (MPS IVA). He is a member of the Hutterite Brethren and genealogic analysis discloses a high inbreeding coefficient for the proband. The proband's sibship is segregating two autosomal recessive disorders, ie, MPS IVA and infantile hypophosphatasia. Two other families each have one or the other of these diseases but not both. The three families are distantly related.

Cartilage↗