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Biomedical subjects

S J Evans

Publications and source records attributed to S J Evans.

At least 19 recordsLinked to original sources
PubMed1992

High dose oral amiodarone loading: electrophysiologic effects and clinical tolerance.

Although amiodarone is an effective drug for the treatment of life-threatening ventricular arrhythmias, no standard oral loading dose protocol has been defined, and patients often undergo prolonged hospitalization for amiodarone loading. High dose (greater than 1,800 mg/day) oral loading has usually been reserved for unstable patients with incessant ventricular tachyarrhythmias. The current study was designed to 1) examine the clinical and electrophysiologic effects of a high dose oral amiodarone loading regimen in more stable patients; and 2) ascertain its safety and tolerance, possibly allowing shortened amiodarone loading periods and potentially decreased length of hospital stay. The study group included 16 patients with a history of recurrent ventricular arrhythmias and decreased left ventricular function, who were refractory to prior antiarrhythmic drug therapy. The oral loading protocol was 50 mg/kg per day of amiodarone for 3 days, then 30 mg/kg per day for 2 days, followed by maintenance therapy of 300 to 400 mg twice daily. Electrophysiologic testing was performed at baseline, on days 1 and 5 and during week 6. Amiodarone and desethylamiodarone levels were measured and symptoms monitored. Clinically, the high dose loading protocol was well tolerated in 15 of the 16 patients. Arrhythmias were rendered noninducible by day 1 in three patients and remained noninducible throughout the study period in two of the three. The remaining patients continued to have inducible ventricular tachycardia. Ventricular tachycardia cycle length and right ventricular effective refractory period both progressively increased significantly over baseline, starting on day 1. The 15 patients who remained in the study had no significant side effects during the loading period.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

Impaired acquisition of the Morris water maze following global ischemic damage in the gerbil.

Five minutes of global ischemia in the Mongolian gerbil impaired acquisition of a Morris water maze task when testing began 72 h after surgery. In spite of extensive damage to CA1 pyramidal cells, ischemic animals eventually learned to locate a submerged platform and performed normally on a subsequent retention test. Animals that were allowed a more protracted recovery period (21 days) acquired the task as readily as control gerbils. These results suggest that undamaged structures within and external to the hippocampal formation allow spatial learning to proceed at a somewhat reduced rate.

Animals↗
PubMed1992

The contrasting effects of parental birthweight and gestational age on the birthweight of offspring.

Investigations on intergenerational effects on birthweight have been carried out using the data of the 1958 British National Birthday Trust Fund cohort and its follow-up to 23 years, the National Child Development Study (NCDS-4), which included information on all births to cohort members by that age. This report is directed particularly at ascertaining the independent effect of parental gestational age on babies' birthweight. The two main findings are a direct association between parental and offspring birthweight (significant for both mothers and fathers after allowing for confounding factors), but an inverse association with parental gestational age (significant only for the mothers). It is postulated that at least part of this effect is mediated through the association between maternal fetal growth rate and their babies' birthweight; the faster the rate the shorter the gestational age for a given birthweight. It was not possible to ascertain what part genetic factors played in this relationship. Larger and more informative intergenerational studies are needed to further knowledge on this question.

Adult↗
PubMed1992

Intergenerational studies of human birthweight from the 1958 birth cohort. 1. Evidence for a multigenerational effect.

OBJECTIVE: To investigate possible multigenerational influences on birthweight. DESIGN: Data from the longitudinal study of one week's births in 1958 up to the age of 23 years, the British National Child Development Study, were utilized. These provide socio-biological information on the parents of the cohort, on the cohort members from birth onwards, and on the pregnancies and the birthweight of any babies born to the cohort members. MAIN OUTCOME MEASURE: The main outcome was the birthweight of babies born to the cohort members, for whom complete intergenerational data were available for 1638 firstborn. Multiple regression modelling was used to investigate any associations between their birthweight and characteristics of their parents and grandparents. RESULTS: Significant positive associations were found between babies' birthweight and parental birthweight but not gestational age. For the babies born to female cohort members additional findings included associations between their birthweight and the height of the maternal grandmother and the social class of the maternal grandfather, even after adjustment for such strong predictors of birthweight as maternal weight, smoking habit in pregnancy and baby's sex and birth order. CONCLUSION: These results thus offer support for a multigenerational influence on birthweight passed through the maternal line.

Birth Weight↗
PubMed1992

Intergenerational studies of human birthweight from the 1958 birth cohort. II. Do parents who were twins have babies as heavy as those born to singletons?

OBJECTIVE: To ascertain whether maternal twinning influences the previously described association between the birthweight of singleton mothers and their infants. DESIGN AND SUBJECTS: The association between the birthweight of singleton parents and their offspring and that between twin parents and their offspring was compared using data from the 23-year-old sample of the 1958 British national birth cohort. The numbers available for full comparison were 1027 female and 611 male singleton cohort members, and 26 female and 17 male twin cohort members and their first singleton livebirths. RESULTS: Of the mothers who had been twins, half had been of low birthweight, and overall their mean weight was 700 g less than that of their singleton counterparts. Nevertheless, the mean birthweight of babies of twin mothers was 133 g, and of twin fathers 94 g, greater than of babies of corresponding singletons. For female, but not male, parents this difference persisted after adjustment for confounding variables. CONCLUSIONS: We suggest two possible reasons for the difference between the weight of babies of twin and singleton mothers. Firstly, the growth of twins becomes retarded late in pregnancy, possibly after a period critical in determining long-term reproductive effects. Secondly, the twin survivors were of higher birthweight than the original twin cohort, whilst the singleton survivors were more representative of all singleton births, thus introducing a possible bias.

Birth Weight↗
PubMed1992

'Pulse' oral calcitriol in uraemic patients: rapid modification of parathyroid response to calcium.

We performed dynamic parathyroid function tests, with generation of parathyroid hormone/ionized calcium (PTH/iCa) response curves, obtained during sequential hypercalcaemic and hypocalcaemic dialysis, on six haemodialysis patients before and after 4-weekly 'pulse' doses of oral calcitriol. There were no significant changes in the pretreatment, 2-week and 4-week values of blood ionized calcium, serum total calcium, phosphate, and alkaline phosphatase. PTH decreased significantly after 4 weeks of treatment with calcitriol (P less than 0.03), and the post-treatment PTH/iCa curves were all displaced leftwards and downwards, indicating a marked inhibitory effect of calcitriol on parathyroid responsiveness across and beyond the physiological range of calcaemia. The mean shift of the PTH/iCa relationship was equivalent to a reduction of iCa of 0.2 mM for any given concentration of PTH, and conversely to a 70% reduction of PTH for any given blood iCa. The results suggest that wide spacing of oral 'pulse' doses of calcitriol can achieve favourable modification of the PTH/iCa relationship, and that dosing interval and dose size, rather than route of administration, may be the major determinants of the previously reported superiority of intravenous over daily oral calcitriol regimens.

Administration, Oral↗
PubMed1991

Good surveys guide.

Explore the source record for details and available documents.

Epidemiologic Methods↗
PubMed1990

Statistics for medical students in the 1990's: how should we approach the future?

Medical statistics teaching in the U.K. has moved over the past twenty years from needing justification to acceptability. In the future teachers need to involve statistical and medical colleagues to improve the content and presentation of their material. While some techniques must continue to be taught, the conceptual aspects of scientific evaluation and assessment will need to increase.

Curriculum↗
PubMed1990

Sperm motility, velocity and migration.

Four different methods for evaluating sperm motility were analysed for experimental error: subjective assessment of a wet film preparation, sperm velocity measured by time-lapse photography, sperm velocity measured by computer analysis and sperm migration across a nucleopore membrane. Subjective assessment of motility was found to be inaccurate, within single observer and between 2 observers. Both methods of measuring mean sperm velocity were accurate, particularly that using the computer analysis system; a high technical failure rate was found using time-lapse photography. Sperm migration across a nucleopore membrane was found to be highly inaccurate. Two groups were then analysed for the predictive value of these tests (excluding sperm migration): 104 proven fertile men and 53 infertile men. Although subjective motility was able to predict from which group the sample came at optimum cut-off with 78% accuracy, computer analysed sperm velocity could predict with overall 91% accuracy at optimum cut-off. Computer analysis of sperm velocity offers a rapid, objective and predictive assessment of sperm function.

Humans↗
PubMed1990

Sperm morphological analysis: comparison of two methods in human semen.

Sperm morphological analysis was performed by 2 methods: light microscopy on Papanicolaou stained material and scanning electron microscopy. Both methods were found to have acceptably low levels of observer error and a positive correlation existed between them. Sperm morphology was analysed by both methods in 2 groups: (1) 104 proven "fertile" men, husbands of women who had just given birth and whose paternity had been proven by HLA studies with greater than 95.5% certainty; (2) 53 infertile men from primary infertile marriages in whom no female cause could be found and excluding those with azoospermia. There was no statistically significant difference in medians between the 2 groups when sperm morphology was analysed by light microscopy, but analysis by scanning electron microscopy did show a significant difference.

Humans↗
PubMed1990

Cerebral palsy: why we must plan for survival.

The survival of children in the South East Thames region, born between 1970 and 1979 and diagnosed as having some form of cerebral palsy was investigated. Of the 732 children studied, 651 (90%) are still alive, and hence cerebral palsy must be regarded as a condition with which people live rather than a condition of which they die. Survival varies considerably among the different diagnostic groups: those suffering from spasic quadriplegia, dyskinetic and 'mixed' cerebral palsy are most severely affected. Our evidence suggests that, though immobility and severe mental subnormality are the strongest predictors of mortality in children with cerebral palsy, the majority of even the most severely affected patients survive to adulthood. It is therefore appropriate to plan for their survival by funding and evaluating programmes to maximise health, independence, and quality of life.

Adolescent↗
PubMed1990

A study of serum zinc, albumin, alpha-2-macroglobulin and transferrin levels in acute and long stay elderly hospital patients.

Serum zinc levels measured by atomic absorption spectrophotometry were found to be low (less than 10.5 mumols/l) in 38% of acute geriatric admissions, 69% of long stay geriatric patients and 19% of a control group of elderly hospital patients with a normal serum albumin. There was a significant positive correlation between serum zinc and serum albumin in all groups. In acutely ill geriatric patients only, there was a weak but statistically significant positive correlation between serum zinc and alpha-2-macroglobulin (A2M) (r = 0.20), P less than 0.05). Serum transferrin was low in 46% of acute geriatric patients and 22% of long stay geriatric patients but there was no correlation between serum zinc and serum transferrin levels in any patient group. There were significant differences in serum zinc, A2M and transferrin levels between the acute and long stay geriatric patients. The differences in serum zinc levels between these patients groups could not be explained by changes in serum A2M, transferrin or albumin. Changes mediated by an acute phase response may have influenced results in the acute geriatric group of patients.

Acute Disease↗
PubMed1990

An inverse relationship between serum zinc and C-reactive protein levels in acutely ill elderly hospital patients.

Serum zinc and C-reactive protein (CRP) levels were measured in two groups of acutely ill geriatric hospital in-patients. Serum CRP levels were greater than 10 mg/l in 62% of the first group and 47% of the second. There was a significant negative correlation between zinc and CRP in both groups (r = -0.33, P less than 0.001, n = 103) and (r = -0.29, P less than 0.001, n = 135 respectively). The serum CRP was raised in 30% of long stay patients (n = 50) and 23% of a control group of elderly hospital patients with a normal serum albumin (n = 71), but there was no correlation between zinc and CRP in these patient groups. The results indicate that an acute phase response influences serum zinc levels in acutely ill geriatric patients. There is reason to believe that a distinction should be made between true zinc deficiency and a low serum zinc secondary to acute zinc redistribution during an inflammatory response. Measurement of CRP may help to distinguish between these two situations. We advise that if the serum zinc is low and CRP is significantly raised, zinc supplements should be avoided and a source of infection should be sought. Following recovery from severe infection low serum zinc levels return to normal while elevated CRP levels fall.

Acute Disease↗
PubMed1989

Automatic speech recognition--can it improve the man-machine interface in medical expert systems?

Computer-aided medical diagnosis has existed for two decades, but has not yet attained widespread acceptance among physicians. It is proposed that automatic speech recognition may be a significant factor in the eventual acceptance of the technology by the medical profession. The current state-of-the-art of automatic speech recognition is briefly surveyed, and problems with the technology are discussed. A potential natural language interface with DIAG, an expert system for aiding in dermatologic diagnosis, is described. A system that has been developed for accepting input of body parts in freestyle format is presented as a prototype for a natural language interface with an automatic speech recognition device.

Diagnosis, Computer-Assisted↗
PubMed1989

Sperm density measurement: should this be abandoned?

Sperm density measurement by means of the Makler chamber was performed on a single semen specimen from 2 groups: 104 proven fertile men and 53 infertile men; 11.5% of the fertile population had a sperm density less than 20 million/ml (median 84, mean 91.3, SD 60.5) and 33% of the infertile population had a sperm density greater than 20 million/ml (median 10, mean 26.9, SD 34.8). There was a statistically significant difference in median between the 2 groups, but when a discriminant analysis was applied, sperm density could predict fertile status with only 68% accuracy at optimum cut-off. Sperm density is valueless in distinguishing fertile from infertile men and is neither useful in diagnosis nor in monitoring the progress of treatment for male infertility. It should be abandoned as a quotable measurement of male fertility.

Adult↗
PubMed1989

The measurement of migration of the acetabular component of hip prostheses.

Individual components of a total hip replacement are difficult to evaluate and quantify. We have studied the assessment of the acetabular component, and conclude that the measurement of migration allows the comparison of implants, although there is no established link between migration and significant loosening. A method of measurement based on clinical radiographs has been developed, and its limitations estimated. The accuracy of the technique was calculated to be +/- 3 mm.

Acetabulum↗