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Biomedical subjects

A Taylor

Publications and source records attributed to A Taylor.

At least 451 records · Page 25Linked to original sources
PubMed1993

Cataract: relationship between nutrition and oxidation.

Opacification of the lens, or cataract, is causally related to the precipitation of proteins or other constituents upon aging. Proteins in the lens are unusually long lived and are subject to extensive damage, including (photo)oxidation. Accumulation of damaged proteins also appears to be due in part to attenuated activity of some proteolytic pathways, which in younger tissue may serve to identify and remove such moieties. The damaged proteins accumulate, aggregate, and precipitate. Compared with other health problems, surgery to remove cataract and related visits to physicians consume the largest proportion of the Medicare budget, i.e., $3.2 billion annually in the United States. The situation is exacerbated in many parts of the world where there is a dearth of ophthalmologists to perform the required number of procedures. Historically efforts to delay cataract assumed a low profile in ophthalmologic research. Recent data, however, indicate that consuming elevated levels of antioxidants such as ascorbate, carotenoids, and tocopherol is associated with delayed development of various forms of cataract. The same beneficial relationship to vision pertains to plasma antioxidant status and to fruit and vegetable intake. Thus, it seems that assuring optimal antioxidant intake can extend lens function. It has been estimated that in the United States over half of the cataract extractions and associated costs would be obviated if cataract could be delayed by 10 years. The data reviewed indicate that optimizing nutrition will help achieve that objective.

Aged↗
PubMed1993

HIV prevalence and HIV risk behaviour among injecting drug users in London and Glasgow.

This paper reports on the British findings from a cross-national study of HIV prevalence and HIV risk behaviour among 1,037 injecting drug users (IDUs) recruited from a variety of treatment- and community-based settings during 1990. Confirmed HIV saliva test results show 12.8% (63) of London respondents and 1.8% (8) of Glasgow respondents to be HIV antibody positive. Among London respondents, a higher rate of prevalence was found in those with no experience of drug treatment. A greater proportion of Glasgow respondents (68%) than London respondents (47%) reported sharing used injecting equipment in the 6 months prior to interview. The majority (88% in both cities) attempted cleaning borrowed equipment, although less than a third (31% in London and 30% in Glasgow) usually used bleach. The majority of respondents (71% in London and 82% in Glasgow) were sexually active with partners of the opposite sex in the last 6 months, and respondents had a mean number of 2.4 non-commercial sexual partners in London and 2.1 in Glasgow. Levels of reported condom use were comparable with reports in the heterosexual population as a whole, with 70% of London respondents and 75% of Glasgow respondents never using condoms with primary partners, and 34% of London and 52% of Glasgow respondents never using condoms with casual partners. Half (48%) of London respondents and 42% of Glasgow respondents reported sexual intercourse with non-injecting private sexual partners, while 14% of female respondents in London and 22% in Glasgow had engaged in prostitution. Levels of risk-taking in each of the two cities indicate the potential for further transmission of HIV among drug injectors, and their sexual and sharing partners.

Adult↗
PubMed1993

Female streetworker--prostitutes in Glasgow: a descriptive study of their lifestyle.

The objective of this study is to describe the lifestyle of a group of female prostitutes. The collection of information was achieved by: (i) using a self administered questionnaire; and (ii) conducting conversational type interviews. Of 85 women attending a health care drop-in centre for female street prostitutes in Glasgow, 63 completed the questionnaire and 72 participated in conversational interviews. For 63 women the mean age of commencement of prostitution was 21 years. Fifty-one (81%) were injecting drug users, their most commonly used drugs being heroin and temazepam. They worked a mean of 5.5 evenings per week and provided sexual services to a mean of 6.4 clients per working day. Less than half of these services were estimated to be vaginal intercourse. While 59/60 women indicated that they always used condoms during vaginal intercourse, this only applied to commercial sex; only 8/47 (17%) always used condoms with their regular sexual partners. Unconventional sexual services, e.g. voyeurism and physical abuse, were commonly provided and clients were often violent. A typical female streetworking-prostitute in Glasgow was aged 25, unemployed, an injecting drug user and had commenced prostitution 4 years before. Her knowledge of HIV/AIDS was good and for vaginal intercourse she almost always used condoms with clients, though probably not with her regular partner. Her main concern was likely to be violence from clients.

Adolescent↗
PubMed1993

The fine structure of the human endometrial glandular epithelium in cases of unexplained infertility: a morphometric study.

In the present study attempts have been made to express in quantitative terms the fine structure of the endometrial glandular epithelium in well-timed biopsies from fertile women during the early luteal phase. Biopsies from women with unexplained infertility have also been examined. Certain abnormalities of glandular maturation were found in these women. The nuclear channel system was not present at day luteinizing hormone (LH) + 4 in the infertile group while at LH + 6 there were more cells containing this feature than seen in the fertile group. There also seem to be abnormalities associated with intracellular deposits of glycogen-rich material and mitochondrial elaboration in the infertile women. Changes in the secretory apparatus and rough endoplasmic reticulum were observed. The evidence from the present study suggests that the endometria in the examined group of infertile women is responsive to steroidal stimulation. This response however, may be delayed or inadequate.

Cell Nucleus↗
PubMed1993

A pitfall in calculating differential renal function in patients with renal failure.

Measurement of relative renal function in azotemic patients can be misleading due to elevated background activity and delayed renal concentration of radiotracer. When there is delayed excretion of the tracer and obvious splenic or hepatic activity superimposed over one of the kidneys, it often is advantageous to delay the differential uptake measurement to allow renal activity to increase and background activity to decrease rather than use the standard 1- to 2- or 2- to 3-minute interval after radiopharmaceutical injection. The accompanying case illustrates the use of delayed images to obtain a more accurate assessment of relative renal function. The measurement must be made before the excretion of tracer into the ureter or bladder.

Acute Kidney Injury↗
PubMed1993

Animal research.

Explore the source record for details and available documents.

Animals↗
PubMed1993

HIV risk behaviours among female prostitute drug injectors in Glasgow.

This paper focuses upon HIV-related risk behaviours of 51 female drug injecting prostitutes, interviewed as part of a serial cross-sectional study of injecting drug users in Glasgow. Forty-five per cent injected with used needles and syringes in the 6 months prior to interview. Condom use in private sexual relations was low with only 9% of those with primary partners and 22% of those with casual partners reporting consistent use of condoms with these partners. In contrast, use of condoms for all commercial sexual encounters was almost universal. Prevalence of HIV was 2.2%. Despite this low prevalence, we conclude that the level of injecting-related and private sexual risk behaviours reported here requires the continuing monitoring of drug injecting prostitutes in Glasgow.

Adolescent↗
PubMed1993

Alterations in erythrocyte chloride content accompanying the changes in erythrocyte hydration and potassium content in normal human pregnancy: a comparison with pregnancy induced hypertension.

OBJECTIVES: To determine whether the change in erythrocyte potassium content in normal human pregnancy is accompanied by a similar change in erythrocyte chloride content. To assess erythrocyte hydration and potassium and chloride content in pregnancies complicated by proteinuric pregnancy induced hypertension. DESIGN: A serial study during and after normal pregnancy. A comparative study during and after pregnancies complicated by proteinuric pregnancy induced hypertension (PIH). Erythrocyte hydration, total osmoles, potassium and chloride and plasma osmolality were determined. SETTING: University teaching hospital, UK. SUBJECTS: Twenty-eight women studied at 14, 28 and 36 weeks of normal pregnancy and ten women with PIH studied during the third trimester of pregnancy. All women were reinvestigated 20 weeks after delivery. RESULTS: The fall of erythrocyte potassium early in normal pregnancy (277.4 vs 265.2 mmol/kg; P < 0.02) and its rise between 28 and 36 weeks (272.3 vs 288.0 mmol/kg; P < 0.005) were accompanied by similar changes in erythrocyte chloride content (151.9 vs 131.1 mmol/kg; P < 0.001 and 129.4 vs 141.3 mmol/kg; P < 0.001, respectively). Plasma osmolality in PIH was raised above that normal in pregnancy (287.2 vs 283.0 mosm/kg; P < 0.005). In PIH, compared to normal pregnancy, erythrocyte hydration (2.00 vs 1.89 l/kg dry weight cells), total osmoles (573.0 vs 534.2 mosm/kg), potassium (303.0 vs 288.0 mmol/kg) and chloride (154.9 vs 141.3 mmol/kg) were greater. CONCLUSIONS: These findings further support the hypothesis that changes in plasma osmolality in pregnancy are secondary to alterations in cell osmoles and serve to limit changes in cell hydration. Erythrocyte composition and plasma osmolality are altered in PIH.

Chlorides↗
PubMed1993

The use of midbrain stimulation to identify the discharges of static and dynamic fusimotor neurones during reflex jaw movements in the anaesthetized cat.

In anaesthetized cats, it was possible to enhance the dynamic sensitivity to stretch of jaw muscle spindle primary afferents by electrical stimulation in the midbrain. This effect was taken to be due to excitation of dynamic fusimotor neurones and was used to identify fusimotor fibres as static or dynamic in recordings from the masseter nerve. During reflex movements, some fusimotor fibres fired tonically, while others were markedly modulated with increases in firing corresponding approximately to muscle shortening. The modulated group had a significantly higher mean resting firing frequency than the tonic group. Midbrain stimulation at points shown to produce dynamic effects on muscle spindle primary afferents increased the discharge frequency of the tonic fusimotor units, but did not significantly affect the modulated fusimotor units. We conclude that the fusimotor fibres in the masseter nerve which fire tonically during reflex jaw movements are probably of the dynamic type, while those which show strongly modulated increases in firing are probably static.

Afferent Pathways↗
PubMed1993

Projection of cat jaw muscle spindle afferents related to intrafusal fibre influence.

1. A method of classification of muscle spindle afferents using succinylcholine (SCh) and ramp stretches has recently been described, which appears to estimate separately the strength of influence of bag1 (b1) and of bag2 (b2) intrafusal fibres. Increase in dynamic difference (delta DD) indicates b1 influence whilst increase in initial frequency (delta IF) indicates b2 influence. The significance of this classification has now been examined by correlation with the strength of synaptic projection of jaw muscle spindle afferents to the fifth motor nucleus (MotV) and the supratrigeminal region (STR) in anaesthetized cats. 2. Projection strength was estimated by computing the extracellular focal synaptic potential (FSP) from spike-triggered averages of 1024 sweeps at 100 microns intervals along tracks through STR and MotV. Trigger pulses were derived from spindle afferent cell bodies of the jaw-closer muscles recorded in the mesencephalic trigeminal nucleus, and characterized by the effect of SCh on their responses to ramp-and-hold stretches. 3. The maximum size of FSPs in tracks traversing STR and MotV ranged from 2.08 to 36.99 microV with a mean of 7.55 microV. The amplitudes were bimodally distributed into roughly equal-sized groups with high and low amplitude FSPs. 4. Mean values of delta IF were significantly greater for the group with large FSPs than for those with small FSPs. There were no significant differences in delta DD. FSP amplitude was significantly positively correlated with delta IF, but not with delta DD. 5. Spindle afferents with high values of FSP amplitude in MotV had a wide range of values of delta DD (b1b2c and b2c groups), while units with large FSPs in STR were all in the b2c category. Some evidence is presented to indicate that this reflects a preferential projection of secondary afferents to the STR. 6. For those units with projection to both STR and to MotV, there was a significant positive correlation between FSP amplitude in the two nuclei. 7. These results indicate that the extent of the b2 influence on spindle afferents predicts the central projection strength better than does the b1 influence. This finding is discussed from the viewpoint of possible developmental and functional issues.

Animals↗
PubMed1993

Mutations in or near the fusion peptide of the influenza virus hemagglutinin affect an antigenic site in the globular region.

We previously described a monoclonal antibody (Y8-10C2) that binds influenza virus hemagglutinin (HA) monomers but not native trimers. In this study, we demonstrated that Y8-10C2 binds to the globular domain of HA and found evidence that its epitope is located at the interface of adjacent subunits. We further showed that at elevated temperatures, the Y8-10C2 epitope is transiently exposed in trimers for antibody binding. Introduction of intrasubunit chemical cross-links into HA reversibly inhibited both Y8-10C2 binding to trimers at elevated temperatures and viral fusion activity, indicating that exposure of the epitope requires the normal conformational flexibility of the molecule. Prolonged incubation of Y8-10C2 with virus at an elevated temperature resulted in neutralization of viral infectivity, allowing selection of neutralization-resistant virus mutants. Mutants were divided into two classes based on a radioimmunoassay in which the virus is attached to polyvinyl: those with reduced affinity for Y8-10C2 or other monoclonal antibodies specific for the globular domain and those with no alteration in their interaction with Y8-10C2 or other antibodies. DNA sequencing of HA genes revealed that the first type of mutants possessed single amino acid substitutions in the Y8-10C2 epitope itself, while remarkably, the second type of mutants possessed single amino acid substitutions in or near the fusion peptide of the HA, which is located in the stem of the HA at a considerable distance from the Y8-10C2 epitope. These findings indicate that the conformational flexibility of the HA affects its antigenicity and that single amino acid substitutions in or near the fusion peptide influence the flexibility of the globular domains.

Antibodies, Monoclonal↗
PubMed1993

Temporal summation--the key to motor evoked potential spinal cord monitoring in humans.

Spinal motor evoked potentials (SMEP) were recorded from tibialis anterior muscle after epidural stimulation of the spinal cord at the low cervical or high thoracic level during scoliosis surgery. By using a double stimulus pulse to produce temporal summation within the spinal cord a maximal CMAP response was readily achieved despite good surgical anaesthesia.

Anesthesia, Epidural↗
PubMed1993

Relationships between acetone, cataracts, and ascorbate in hairless guinea pigs.

Acetone is one of the most commonly used industrial solvents. Recent literature indicated that in guinea pigs, but not rabbits, acetone is cataractogenic and that elevated acetone exposure is also associated with depressed aqueous ascorbate levels. Other work indicated that aqueous and lens levels of ascorbate are closely linked and that depressed ascorbate status is related to cataract. Taken together, these papers suggested that acetone exposure, depressed ascorbate levels, and cataract are related, possibly causally. While the possibility that acetone is cataractogenic presented a major health concern, it also presented an opportunity to develop a new model of cataract in which hypotheses regarding anticataractogenic effects of ascorbate could be tested. Albino hairless guinea pigs are immunocompetent animals derived from albino Hartley guinea pigs. Animals were fed diets containing low (4.9 mg/day) and high (55 mg/day) levels of ascorbate. This resulted in distinct groups of animals, one with high tissue ascorbate levels and the other with low, but nonscorbutic ascorbate levels. The tissue levels of ascorbate and the relationship between tissue ascorbate levels and dietary intake indicate that with respect to ascorbate uptake, transport, and concentration, these animals are identical to the standard albino Hartley animals. Daily exposure to acetone was extended for 6 months, with a total applied dose of 65 ml. Absorption of the solvent was maximized by the use of hairless animals. Despite exposure of the animals to higher levels of acetone, in no case (n = 20) were cataracts observed over a 2-year period. This is consistent with results using rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetone↗
PubMed1993

Ischemia-reperfusion injury in the isolated rat lung. Role of flow and endogenous leukocytes.

Microvascular lung injury caused by ischemia-reperfusion (IR) may occur via leukocyte-dependent and leukocyte-independent pathways. Leukocyte-endothelial adhesion may be a rate-limiting step in IR lung injury. Leukocyte adhesion to microvascular endothelium occurs when the attractant forces between leukocyte and endothelium are greater than the kinetic energy of the leukocyte and the vascular wall shear rate. We hypothesized (1) that isolated, buffer-perfused rat lungs are not free of endogenous leukocytes, (2) that endogenous leukocytes contribute to IR-induced microvascular injury as measured by the capillary filtration coefficient (Kfc), and (3) that a reduction of perfusate flow rate would potentiate leukocyte-dependent IR injury. Sixty lungs were divided into four groups: (1) low-flow controls, (2) high-flow controls, (3) low-flow IR, and (4) high-flow IR. Microvascular injury was linearly related to baseline perfusate leukocyte concentrations at both low (r = 0.78) and high (r = 0.82) flow rates. Kfc in the high-flow IR group (0.58 +/- 0.03 ml/min/cm H2O/100 g) was less (p < 0.05) than Kfc in the low-flow IR group (0.82 +/- 0.07), and in both groups Kfc values were significantly greater than low-flow (0.34 +/- 0.03) and high-flow (0.31 +/- 0.01) control Kfc values after 75 min. Retention of leukocytes in the lung, evaluated by a tissue myeloperoxidase assay, was greatest in the low-flow IR group. We conclude (1) that isolated, buffer-perfused rat lungs contain significant quantities of leukocytes and that these leukocytes contribute to IR lung injury, and (2) that IR-induced microvascular injury is potentiated by low flow.

Analysis of Variance↗
PubMed1993

Identification of sources of lead exposure among children in Arar, Saudi Arabia.

The concentrations of lead and the isotopic ratios of lead, 206Pb:207Pb, were measured by inductively coupled plasma-mass spectrometry in environmental specimens, cosmetics and traditional remedies. The ratios were compared with those found in blood samples of Saudi children who had increased concentrations of total blood lead. The isotopic ratios in the blood specimens (1.144 +/- 0.027) were not significantly different from those determined in cosmetics and remedies (1.152 +/- 0.031) and indicated that these were the likely sources of exposure rather than the lead contained in petrol which had an isotopic ratio of 1.207.

Child↗
PubMed1993

Movement sequencing disorders in Parkinson's disease.

Ten PD patients and ten age-matched normal controls learned a sequence of 3 or 4 different hand movements to a criterion of 5 consecutive correct trials. They also performed a control sequence of 3 or 4 movements which involved the repetition of the same hand posture. Trials to reach criterion, errors, total response time and its components, response time for each movement and inter-response time were examined. There were no group differences in trials to criterion or errors. Total movement time as well as response and inter-response times were significantly longer for the PD patients, however, but only for sequences involving different hand movements not for the repetitive sequences. The relative timing of the responses was also different with the PD patients spending proportionately more time on each response and the controls spending more time between responses. The implications of these findings for understanding the movement sequencing impairments in PD are discussed.

Aged↗