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Biomedical subjects

B Morgan

Publications and source records attributed to B Morgan.

At least 37 records · Page 2Linked to original sources
PubMed1988

Blood lipid concentrations and other cardiovascular risk factors: distribution, prevalence, and detection in Britain.

To establish the distribution of blood lipid concentrations and the prevalences of other risk factors for cardiovascular disease in Britain 12,092 men and women aged 25-59 in Glasgow, Leicester, London, and Oxford were studied. Subjects were selected by opportunistic case finding, in which patients consulting their general practitioner for any reason were offered a health check by appointment, or random selection from age-sex registers, in which an invitation for a health check was posted. The overall rate of response was 73%, being 91-94% by opportunistic case finding and 36-63% by random selection. At the health check subjects answered a brief questionnaire about risk factors for cardiovascular disease, and their height, weight, and blood pressure were recorded; a blood sample was taken for measuring plasma concentrations of cholesterol, triglyceride, high density lipoprotein cholesterol, and glucose. The mean cholesterol concentrations were 5.9 (SD 1.2) and 5.8 (1.2) mmol/l in men and women, respectively. In London the mean value was 5.5 (1.2) mmol/l for both men and women and was significantly lower than mean values in the three other centres, among which there were no significant differences. In men and women aged 25-29 concentrations were similar but they increased in men until the age of 45-49, after which they showed no further increase; in women concentrations did not increase until the age of 40-44 and by the age of 50-59 values were higher than in men. Mean triglyceride concentrations were significantly higher in men than in women (1.8 (1.4) v 1.3 (0.9) mmol/l, respectively), and trends with age were similar to those for cholesterol concentrations, except that at no age were values higher in women than in men. Mean triglyceride values overall were higher in Glasgow and London than in Oxford and Leicester. Body mass index was higher in Glasgow and London than in the other two centres and correlated with systolic and diastolic blood pressures and triglyceride concentration. In addition, subjects in Glasgow smoked significantly more than those in the other centres. These observations could contribute to the higher rate of coronary heart disease in Glasgow. Plasma lipid concentrations and the prevalences of other risk factors for cardiovascular disease were similar in subjects selected by opportunistic case finding and by random selection. In Britain cholesterol values have changed little during the past 12 years despite dietary recommendations and health education.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1988

Nerve growth factor binding in aged rat central nervous system: effect of acetyl-L-carnitine.

The nerve growth factor protein (NGF) has been demonstrated to affect neuronal development and maintenance of the differentiated state in certain neurons of the peripheral and central nervous system (CNS) of mammals. In the CNS, NGF has sparing effects on cholinergic neurons of the rodent basal forebrain (BF) following lesions where it selectively induces choline acetyltransferase (ChAT). NGF also induces ChAT in the areas to which BF provides afferents. In aged rats, there is a reduction in the NGF-binding capacity of sympathetic ganglia. Here, we wish to report that there is a decrease in the NGF-binding capacity of the hippocampus and basal forebrain of aged (26-month-old) rats as compared to 4-month-old controls but no change in NGF binding in cerebellum. In all instances, equilibrium binding dissociation constants did not differ significantly. Treatment of rats with acetyl-L-carnitine, reported to improve cognitive performance of aged rats, ameliorates these age-related deficits.

Acetylcarnitine↗
PubMed1988

Deep tectal cells in pigeons respond to kinematograms.

Deep tectal neurons in pigeons respond selectively to moving visual stimuli, and are inhibited by large background patterns moved in-phase with these stimuli. In this investigation we demonstrate that these same deep tectal neurons respond equally well to kinematograms as they do to traditional luminance contrast stimuli typically employed in visual experiments. Computer generated kinematograms, the motion domain equivalents of random dot stereograms, were used as stimuli in these experiments. These kinematograms, where a small centrally located set of random dots is moved coherently in one direction while the remaining dots are moved in a different direction, thus constitute a pure motion stimulus where the stimulus form is only visible in the dynamic pattern, but does not exist on any single frame. Both 'object' configured and 'hole' configured kinematograms were employed; the former appearing as regions of texture moving over, or in front of, the background texture, while the latter appear as windows through which a more distant textured surface is revealed. Extracellular recordings from isolated deep tectal cells showed that all units responded in a very similar manner whether the stimulus was an 'object' configured kinematogram or the more traditional luminance contrast variety. This similarity included directional selectivity, the in-phase inhibition anti-phase facilitation effect, and sensitivity to opposed motion independent of direction. However, when the kinematograms were configured as 'holes' none of the units tested responded to these stimuli. The significance of these observations for tectal functioning, image segmentation through motion and animal camouflage is discussed.

Animals↗
PubMed1988

Delta-9-tetrahydrocannabinol during pregnancy in the rat: effects on development of RNA, DNA, and protein in offspring brain.

Either 15 or 50 mg/kg of delta-9-tetrahydrocannabinol (THC) was administered from Day 2 through Day 22 of gestation. Pair-fed and nontreated groups served as controls and all treated and control litters were fostered at birth to untreated dams. To determine the effects of THC on offspring brain development, DNA, RNA and protein values were determined at 7, 14, and 21 days of postnatal age. DNA and RNA levels appeared unaffected by THC but brain protein levels of the 50 mg/kg offspring were significantly lower than in the other groups at Day 7 and 14. This suggests that the high THC dose inhibited protein synthesis for at least the first 14 days of life. Subsequently, protein levels of the 50 mg/kg offspring increased rapidly so that there were no differences between any of the groups at 21 days of age. These findings for developing CNS parallel the delayed rate of somatic growth previously reported from our laboratory and suggest a transitory rather than a permanent effect of THC on both somatic and brain growth. We also found that THC produces a significant dose-related increase in the sex-ratio of live male-to-female offspring, a finding we have reported previously.

Animals↗
PubMed1988

H2 antagonists and bupivacaine clearance.

The effect of the H2 receptor antagonists cimetidine and ranitidine on bupivacaine clearance was assessed in women scheduled to undergo elective Caesarean section under epidural anaesthesia. Thirty-six women were randomly allocated to receive either no medication, cimetidine 400 mg or ranitidine 150 mg on the night prior to and on the morning of surgery. No significant difference was found between the peak bupivacaine levels: the mean (SD) values were 0.74 (0.17) microgram/ml, 0.81 (0.38) microgram/ml and 0.70 (0.24) microgram/ml in the control, cimetidine and ranitidine groups, respectively. Similarly, the H2 receptor antagonists did not alter the plasma bupivacaine against time curves, half-life or bupivacaine clearance in the three groups studied.

Adult↗
PubMed1987

Production and characterisation of a human monoclonal antibody to cytomegalovirus and its use in an early nuclear fluorescence assay.

A human monoclonal antibody to cytomegalovirus (CMV) was produced by transforming peripheral blood mononuclear cells of a patient with recent CMV infection. It is directed against a late antigen located in the nucleus of CMV infected fibroblasts at 24-72 hours postinfection and immuneprecipitates 65K and 48K proteins from 35S-labelled CMV infected cells. Results of its use in an early nuclear fluorescence assay for rapid diagnosis are presented.

Adult↗
PubMed1987

Effects of pre-weaning undernutrition on 21 day-old male rat skull form as described by the finite element method.

Conventional Roentgenographic Cephalometric Methods (RCM) have certain conceptual and geometric constraints that ensure that their descriptions of cephalic growth and comparisons of cephalic form are reference-frame-dependent; and it is impossible to determine which, if any, RCM reference frame provides a biologically more correct description or comparison. The use of the concepts of continuum mechanics and of the numerical techniques of the Finite Element Method (FEM) overcomes these constraints and provides reference-frame-independent (invariant) growth descriptions and form comparisons. In the FEM, the structure of the head is subdivided (discretized) into a number of smaller, finite, elements. The FEM then describes the growth behavior, or compares the form, of the entire continuum of points enclosed with each element independently; in RCM only the behaviors, or comparisons, of the landmark points are described. The FEM is described and its use illustrated by a comparison of the cephalic forms of 4 groups of weanling (21 d old) rats. The 1st (control) group is derived from normally nourished dams, while the other 3 groups are derived from dams who were malnourished throughout the weaning period in 3 group specific manners. The FEM permitted reference-frame-independent comparisons of the 4 different, and group specific, head forms. These differences were reflected in the forms of each of the finite elements. The differences in element forms between the 4 groups were shown to be related primarily to nutritionally produced alterations of either neurocranial or splanchocranial viscera. These differences were expressed in the alterations of the forms of the continua enclosed within the boundaries of the several finite elements, and secondarily in the form of the cranial skeleton.

Animals↗
PubMed1987

Colectomy and ileostomy in the management of ulcerative colitis.

For 30 years, colectomy with ileostomy has been the mainstay of the surgical treatment for ulcerative colitis. Between 1963 and 1985, 535 patients with inflammatory bowel disease were admitted to the Royal Prince Alfred Hospital in Sydney, Australia; 471 had ulcerative colitis and 64 Crohn's colitis. One hundred and eight-six of these patients underwent colonic resection. The proportion of patients who underwent surgery was the same for both disorders. There have been no deaths resulting from the surgical management of inflammatory bowel disease at our hospital since 1965. These patients should be treated safely by standard means before the more elaborate sphincter-saving procedures, currently recommended, are tried.

Colectomy↗
PubMed1986

Effect of sustained exercise on concentrations of plasma aromatic and branched-chain amino acids and brain amines.

In both trained and untrained rats, exercise increased the plasma concentration ratio of aromatic amino acids to branched-chain amino acids which might favour entry of the aromatic amino acids into the brain. Exercise in trained rats did not change the brain concentration of 5-hydroxytryptamine but increased that of 5-hydroxyindole acetic acid. Exercise in the untrained rat increased the concentration of brain tryptophan and that of 5-hydroxytryptamine but that of 5-hydroxyindole acetic acid was unchanged. The increased concentration of 5-hydroxytryptamine in untrained rats might be involved in central fatigue.

Amino Acids, Branched-Chain↗
PubMed1986

Typing and subtyping of herpes simplex isolates by monoclonal fluorescence.

The type specificity of 16 herpes simplex monoclonal antibodies was tested on 50 isolates previously typed by endonuclease restriction. A panel of antibodies was selected and used to type isolates from 50 primary and 50 recurrent genital infections. Sixty-four isolates from 18 patients followed up for six months were subtyped by using a larger panel of monoclonal antibodies and predominant HSV1 and HSV2 subtypes were demonstrated. In addition to confirming recurrences, four possible reinfections were identified. Type-specific differences in the location of viral antigens in infected cells were noted and a possible association of this finding with the type-specific differences in rates of recurrence of genital infections discussed.

Antibodies, Monoclonal↗
PubMed1986

Spontaneous loss of HBeAg and the prevalence of HTLV-III/LAV infection in a cohort of homosexual hepatitis B virus carriers and the implications for antiviral therapy.

The future design of controlled trials of antiviral therapy which might include homosexual hepatitis B virus (HBV) carriers requires base-line data on the spontaneous rate of loss of HBeAg and the prevalence of human T-lymphotropic virus III (HTLV-III/LAV) infection. Fifty-one untreated HBsAg and HBeAg-positive homosexual HBV carriers were followed for a median HBeAg-positive time of 23.5 months (range 6-85.5). Ten lost HBeAg, giving an annual rate of spontaneous loss of HBeAg of 10%. This rate is considerably higher than the apparent rate in a previous report and has considerable implications for the interpretation of previous, and the design of future, controlled trials in this population. A rapid rise in the prevalence of anti-HTLV-III/LAV amongst HBV carriers was demonstrated from 1981 such that by 1984 over 60% of HBV carriers were anti-HTLV-III-positive. HBV-DNA polymerase levels were not significantly different in asymptomatic anti-HTLV-III/LAV-positive compared to anti-HTLV-III/LAV-negative HBV carriers. Nevertheless, since chronic HTLV-III/LAV infection in its later stages may potentiate HBV replication, it is a factor that will need to be considered together with many others in any trial stratification procedure.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Recombinant retroviruses that transduce individual polyoma tumor antigens: effects on growth and differentiation.

We have constructed infectious retroviral vectors, derived from Moloney murine leukemia virus, that efficiently transduce the polyoma virus tumor (T) antigens individually. The parental vector we have chosen [pZIP-NeoSV(X)1] expresses a dominant selectable marker for neomycin resistance and is a shuttle vector capable of propagation in both eukaryotic and prokaryotic cells, thus facilitating its use in structure-function studies. To address the relationship between polyoma T-antigen tumorigenesis and the effects of individual T antigens on growth control and differentiation, we used these vectors to introduce and stably express large, middle-sized, or small T antigens into mouse fibroblasts and preadipocytes. All cDNAs introduced into the vector are expressed stably even in the absence of selective pressure. The stable expression of small T antigen is noted particularly because cell lines expressing small T antigen have not been readily available prior to the use of retroviral vectors. Small T antigen-induced increase in saturation density of NIH 3T3 cells can be scored on the basis of the morphology of drug-resistant colonies. Middle-sized T antigen eliminates the growth requirement of NIH 3T3 cells for epidermal growth factor in a defined medium and permits growth in platelet-poor plasma, indicating elimination of the platelet-derived growth factor requirement as well. Large T antigen suppresses mouse preadipocyte (3T3-F442A) differentiation. These vectors and these functional assays of T-antigen activity permit genetic analysis of the relationship between tumorigenesis by T antigens and the alteration of cellular growth and differentiation.

Adipose Tissue↗
PubMed1986

Comparison of buffering capacity in patients on hemodialysis and continuous ambulatory peritoneal dialysis.

A standard acid loading test was used to assess the buffering capacity in 9 hemodialysis (HD) and 25 continuous ambulatory peritoneal dialysis (CAPD) patients. There was a significant increase in H+ concentration and a decrease in plasma bicarbonate levels after the acid loading in all patients; however, PaCO2 did not change significantly. CAPD patients tolerated the acid load better, at least in the first 2 h, than HD patients. The brief duration of experiments did not allow us to observe differences, if any, in the recovery rates between HD and CAPD patients. CAPD patients tolerated the acid load equally, whether studied with or without fresh dialysate in the peritoneal cavity. Their tolerance to the acid load did not change with an increasing duration of the CAPD therapy. Baseline values and acid tolerance curves were similar in CAPD patients on regular Dianeal (lactate 35 mEq/l) and Dianeal PD2 (lactate 40 mEq/l). It is concluded that the buffering capacity is marginally higher in CAPD than in HD patients, although the baseline acid-base parameters were essentially identical.

Acid-Base Imbalance↗