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Biomedical subjects

J Stevenson

Publications and source records attributed to J Stevenson.

At least 19 recordsLinked to original sources
PubMed1996

Exogenous glutamate concentration regulates the metabolic fate of glutamate in astrocytes.

The metabolic fate of glutamate in astrocytes has been controversial since several studies reported > 80% of glutamate was metabolized to glutamine; however, other studies have shown that half of the glutamate was metabolized via the tricarboxylic acid (TCA) cycle and half converted to glutamine. Studies were initiated to determine the metabolic fate of increasing concentrations of [U-13C] glutamate in primary cultures of cerebral cortical astrocytes from rat brain. When astrocytes from rat brain were incubated with 0.1 mM [U-13C] glutamate 85% of the 13C metabolized was converted to glutamine. The formation of [1,2,3-13C3] glutamate demonstrated metabolism of the labeled glutamate via the TCA cycle. When astrocytes were incubated with 0.2-0.5 mM glutamate, 13C from glutamate was also incorporated into intracellular aspartate and into lactate that was released into the media. The amount of [13C] lactate was essentially unchanged within the range of 0.2-0.5 mM glutamate, whereas the amount of [13C] aspartate continued to increase in parallel with the increase in glutamate concentration. The amount of glutamate metabolized via the TCA cycle progressively increased from 15.3 to 42.7% as the extracellular glutamate concentration increased from 0.1 to 0.5 mM, suggesting that the concentration of glutamate is a major factor determining the metabolic fate of glutamate in astrocytes. Previous studies using glutamate concentrations from 0.01 to 0.5 mM and astrocytes from both rat and mouse brain are consistent with these findings.

Alanine↗
PubMed1995

HeLa plasma membranes bind the antitumor sulfonylurea LY181984 with high affinity.

Homogenates, total particulate and plasma membranes of cultured HeLa S cells bound the tritiated antitumor sulfonylurea [3H]LY181984 with high affinity (Kd of 20 to 50 nM). Highest affinity binding (Kd of 25 nM) was to purified plasma membrane. The number of binding sites, estimated to represent 30 to 35 pmol/mg protein, would represent a low abundance constituent representing about 1/1000 of the total plasma membrane proteins. When corrected for mitochondrial uptake, binding recoveries of about 80% were achieved. Of the recovered specific radioactivity bound, approximately 90% was associated with the total particulate fraction. Of this, nuclei- and plasma membrane-free total membranes bound little or no [3H]LY181984 with high affinity. The high-affinity binding was restricted primarily to the plasma membranes. All fractions exhibited varying degrees of lower affinity binding indicative of a heterogeneous array of components capable of binding [3H]LY181984 at high concentrations of LY181984. Enrichment of 5-fold over total homogenates of high-affinity binding compared favorably to a 6.7-fold enrichment of the plasma membrane marker enzyme 5'-nucleotidase determined in parallel. We conclude that plasma membranes of HeLa cells contain high-affinity binding sites of low abundance for the antitumor sulfonylurea LY181984 and that the high-affinity sites are associated predominantly with the plasma membrane.

Antineoplastic Agents↗
PubMed1995

Schedule for oral-motor assessment (SOMA): methods of validation.

The Schedule for Oral Motor Assessment (SOMA) was developed for the purpose of objectively rating the oral-motor skills of preverbal children, with a view to identifying areas of deficient abilities that could have clinical significance. The instrument can be administered without special equipment, by a trained observer. Oral-motor function is assessed across a range of food textures and fluids. Ratings of oral-motor skills are largely made post hoc by analysis of a videorecording of the test administration. The test-retest and interrater reliability of the instrument have been shown to be excellent. Criterion validity was investigated by means of a novel 'seeded cluster analysis' procedure in which 127 young children were assessed, most of whom were between 8 and 24 months of age. Ten percent of the sample had known abnormal oral-motor function in association with cerebral palsy (ages between 12 and 42 months). Not only was criterion validity satisfactorily established by the analysis but an abbreviated version of the SOMA--suitable for screening purposes--was developed. This has been shown to have a positive predictive validity greater than 90% and sensitivity greater than 85% for the detection of infants with clinically significant oral-motor dysfunction.

Cerebral Palsy↗
PubMed1995

Sucking wounds of the limbs.

Subcutaneous emphysema affecting a limb in isolation is rare. Three cases of subcutaneous emphysema caused by a sucking wound of the limb are presented. Differentiation from infection with a gas-forming organism is imperative. This distinction can be made if a number of factors are taken into consideration. These include, concise knowledge of the history and mechanism of injury, and in particular, full appreciation of the amount of energy transfer causing the wound, the macroscopic appearance of the wound, the presence or absence of systemic symptoms, the time from injury to the development of subcutaneous emphysema, and the radiographic appearance of the soft tissues.

Adult↗
PubMed1995

Development of factor-score-based models to explain and predict maximal box-lifting performance.

The objectives of the study were threefold: (1) to develop factor-score-based models to predict maximum mass on a box-lifting task using multiple regressions; (2) to compare predictive and explanatory powers of factor-score-based models to models derived from data-level variables; and (3) to apply these findings to ergonomic research and practical problem-solving situations. Forty-eight volunteers (25 women and 23 men) completed a maximal box-lifting task and a maximal isoinertial lifting test on an Incremental Lifting Machine (ILM). Dynamic data collected during isoinertial testing were summarized into 32 lift parameters, and then subjected to principal components analyses using the 'FACTOR PROCEDURE' from the Statistical Analysis System (SAS). Factor scores were calculated for each participant on each of the four factors comprising the final solution, and multiple regression equations for men, women and combined data were generated using the 'GENERAL LINEAR MODELS' procedure from SAS. Results revealed that prediction of box-lifting performance was optimized when regression equations were developed using numerous data-level variables as predictors, i.e., all 32 lift parameters and ILM mass. In comparison, explanation was enhanced but predictive capabilities were reduced when linear models were formed using ILM mass and the factor scores derived from analyses of isoinertial lifting. The use of variables loading on the factors gave slightly increased predictive power than did the factor-score-based models. Similar trends in predictive and explanatory powers appeared when the data were analysed according to gender. Ergonomic applications of factor-score-based models were discussed with regard to ongoing research as well as to practical problem-solving situations. It was concluded that the advantages and usefulness of factor-score-based models warranted their inclusion in future investigations of lifting performance.

Adult↗
PubMed1995

The impact of child IQ, parent IQ and sibling IQ on child behavioural deviance scores.

In an epidemiological sample of 411 13-year-old twins of normal intelligence, both parents and teachers reported more behavioural problems among children with lower IQs. This was not attributable to the effects of parental IQ or social class and was not entirely mediated by lower scholastic attainments. Different causal models are discussed: "rater bias" and "IQ is a consequence" explanations seem less plausible than "IQ is a cause" and "IQ is a marker" explanations. Higher parental IQ was associated with more emotional symptoms in the child, both by parental and school report. There was no evidence that being brighter or less bright than a (twin) sibling influenced behavioural deviance, casting doubt on the importance of contrast effects.

Adolescent↗
PubMed1995

Establishing baseline data in cancer registration in northern England: implications for Health of the Nation targets.

OBJECTIVE: To assess the completeness and accuracy of cancer surveillance data relevant to Health of the Nation targets. DESIGN: A comparison of locally ascertained data on cancer with recorded cancer registry sources in selected diagnoses. SETTING: The district of South West Durham within the Northern Regional Health Authority. PATIENTS: All patients with lung, skin, and malignant cervical cancer who were resident and diagnosed in the district or identified in the Northern Region Cancer Registry during the calendar period 1989-91. MAIN RESULTS: Of 544 cases of cancer identified from all available sources, 448 (95.8%) were registered, ranging from 93.9% for malignant cervical cancer to 96.7% for skin cancer. In 448 cases which were both identified locally and registered, 53 (11.8%) showed disagreements between local sources and register data, involving classification of site and timing of registration. Twenty three cases were identified locally but were not registered, 22 registered but not identified locally, and 51 registered with the casenotes missing locally. CONCLUSIONS: Any real achievement of Health of the Nation targets may be masked by changes over time in the accuracy and completeness of information systems. In assessing the achievement or otherwise of targets, it is important to be aware of any differences in the completeness and accuracy of the baseline data compared to future measurements.

England↗
PubMed1995

Multiple personality disorder in an intellectually disabled man: a case report.

The case of a young man with the dual diagnoses of severe intellectual handicap (IQ 30 and mental age 4 years) and Multiple Personality Disorder is presented. The intellectual handicap is probably due to hypoxia in infancy and the Multiple Personality Disorder follows prolonged physical and sexual abuse. The patient frequently switches between any of nine discrete but incompletely formed identities. Although some personalities seem more capable than others, all have similar levels of disability on testing. The diagnosis of psychiatric disorders coexistent with the intellectual handicap is hindered by the difficulty in separating psychiatric phenomena from the behavioural disturbances associated with the disability. Differential diagnosis and management are discussed.

Adult↗
PubMed1994

Low vaccination levels of US preschool and school-age children. Retrospective assessments of vaccination coverage, 1991-1992.

OBJECTIVE: To obtain estimates on (1) the percentage of children who were up-to-date on the recommended childhood vaccination series, (2) the percentage of children who were age-appropriately immunized, and (3) coverage levels by individual vaccines. DESIGN: Vaccination levels were estimated by conducting retrospective immunization coverage surveys of the school health records of children entering kindergarten or first grade in the 1990-1991 or 1991-1992 school year. A multistage cluster survey design was used. SETTING: Survey sites were selected from among the 60 largest urban areas in the United States. One small city and one rural area were selected for comparison. RESULTS: By their second birthday, 11% to 58% (median, 44%) of the children were fully vaccinated. Stricter measurement criteria lowered coverage levels further. Completed series levels at school entry were 71% to 96% (median, 87%). CONCLUSIONS: Vaccination levels at the second birthday were far below the goal for the year 2000. All health providers need to administer vaccines according to the recommended schedule.

Child↗
PubMed1994

Potential impact on vaccination coverage levels by administering vaccines simultaneously and reducing dropout rates.

BACKGROUND: Retrospective immunization coverage surveys conducted during 1991 and 1992 demonstrated that coverage levels for the routine childhood vaccines by 24 months of age in selected urban areas of the United States ranged from 10% to 52%, far below the US Public Health Service goal of 90%. Therefore, appropriate programmatic changes must be identified and incorporated. METHODS: We analyzed coverage survey data collected from 21 sites to measure the potential impact on coverage levels of implementing selected changes in vaccination practices. In a multistaged cluster survey design, school health records of kindergarten or first-grade students were randomly selected and dates of vaccination assessed. We evaluated changes in the vaccination practices, such as eliminating missed opportunities for simultaneous administration of vaccines and ensuring that children initiated the vaccination series on time (ie, by 3 months of age). We then calculated potential increases in coverage levels for a best-case scenario. RESULTS: From 77% to 96% of all children in the 21 sites had received at least one vaccination by their first birthday. Children were 2.3 to 17 times more likely to be up to date on their vaccinations by 24 months of age if they were up to date at 3 months of age. Each child had many opportunities for the simultaneous administration of diphtheria and tetanus toxoids and pertussis (DTP) vaccine, oral polio vaccine (OPV), and measles-mumps-rubella (MMR) vaccine that, if used appropriately, could have potentially raised coverage levels by 12% to 22% (median, 17%). The highest coverage levels could have been attained if all children had started the series on time and if advantage had been taken of all opportunities for simultaneous vaccination. Coverage levels for four doses of DTP vaccine, three doses of OPV, and one dose of MMR vaccine would have increased from a baseline of 10% to 52% to levels of 54% to 83%. CONCLUSIONS: Although the majority of children received a vaccination by their first birthday, the coverage level at 24 months of age was low. Tracking systems are needed to ensure that children do not drop out of the system once they have begun the vaccination series. In addition, all children who are late in beginning their vaccination series are at increased risk of not completing the recommended vaccination series on time, and these children need intensive follow-up and recall efforts. Also, providers need to administer all needed vaccines simultaneously.

Child, Preschool↗
PubMed1994

Autogenic-feedback training: a potential treatment for orthostatic intolerance in aerospace crews.

Postflight orthostatic intolerance has been identified as a serious biomedical problem associated with long-duration exposure to microgravity in space. High priority has been given to the development of countermeasures for this disorder that are both effective and practical. A considerable body of clinical research has demonstrated that people can be taught to increase their own blood pressure voluntarily, and that this is an effective treatment for chronic orthostatic intolerance in paralyzed patients. The current pilot study was designed to examine the feasibility of adding training in control of blood pressure to an existing preflight training program designed to facilitate astronaut adaptation to microgravity. Using an operant conditioning procedure, autogenic-feedback training (AFT), three men and two women participated in four to nine training (15-30-minute) sessions. At the end of training, the average increase in systolic and diastolic pressure, as well as mean arterial pressures, that the subjects made ranged between 20 and 50 mm Hg under both supine and 45 degrees head-up tilt conditions. These findings indicate that AFT may be a useful alternative treatment or supplement to existing approaches for preventing postflight orthostatic intolerance. Furthermore, the use of operant conditioning methods for training cardiovascular responses may contribute to the general understanding of the mechanisms of orthostatic intolerance.

Adult↗
PubMed1994

Behaviour problems and pre-school intellectual attainment: the associations of hyperactivity and conduct problems.

The relationship between behaviour problems and intelligence was examined in a sample of 106 three-year-old boys and girls selected for the presence of either conduct problems or hyperactivity. Parents' reports of hyperactivity, but not conduct problems, were negatively related to IQ scores for both boys and girls. There was a significant sex difference in the association between conduct problems and IQ. For girls IQ was positively correlated with conduct problems. The implications of the results for existing models of the relationship between behavioural deviance and cognitive functioning in childhood is discussed.

Aggression↗
PubMed1994

PROM management.

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Anti-Bacterial Agents↗
PubMed1994

The 'one-shot' intravenous pyelogram: is it indicated in unstable trauma patients before celiotomy?

UNLABELLED: Although contrast studies are valuable in assessing renal function and identifying injury in trauma victims, we questioned the use of "one-shot" intravenous pyelograms (IVPs) in unstable patients. Retrospective review of 926 IVPs performed over 4.5 years identified 239 preoperative "one-shot" IVPs in patients for whom evaluation in the radiology suite was felt to be unsafe. Of these IVPs, 53 had abnormal findings and 183 had normal findings. Three patients' records were lost. In the 53 patients with abnormal IVP results, injuries were confirmed at surgery in 39. In three cases, an abnormal appearing IVP provided the only indication for renal exploration leading to nephrectomy or revascularization. In the remaining 14 patients with abnormal IVPs, the kidneys were found to be normal at surgery. In the 183 patients with normal IVPs, 14 had injuries that required nephrectomy, renal vein ligation, renorrhaphy, or perinephric drainage. The IVP assessment of contralateral renal function played no role in the decision to perform nephrectomy. CONCLUSIONS: Eight percent of patients with normal IVP findings had renal injuries not detected by "one-shot" IVP, and 26% of patients with abnormal IVP findings had no intraoperative evidence of renal injury. Delaying definitive therapy to obtain a preoperative "one-shot" IVP in an unstable patient is not warranted.

Abdominal Injuries↗