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Biomedical subjects

G Shepherd

Publications and source records attributed to G Shepherd.

At least 19 recordsLinked to original sources

1-3 connectivity composite material made from lithium niobate and cement for ultrasonic condition monitoring at elevated temperatures.

We have designed, manufactured and tested a piezoelectric composite material to operate at temperatures above 400 degrees C. The material is a 1-3 connectivity composite with pillars of Z-cut lithium niobate in a matrix of alumina cement. The composite material produced shorter pulses than a monolithic plate of lithium niobate and remained intact upon cooling. Results are presented from room temperature and high temperature testing. This material could be bonded permanently to a test object, making it possible to carry out condition monitoring over an extended period. A new excitation method was also developed to enable remote switching between array elements.

Journal Article↗

Efficacy of the cation exchange resin, sodium polystyrene sulfonate, to decrease iron absorption.

BACKGROUND: Iron is not bound by charcoal; therefore, a method of binding iron in the gastrointestinal tract to prevent absorption in iron overdose is needed. This study investigated the efficacy and safety of sodium polystyrene sulfonate to prevent absorption of iron in human volunteers. METHODS: Six adult volunteers completed this prospective crossover trial. Following an oral dose of elemental iron 10 mg/kg, each subject received sodium polystyrene sulfonate 30 g or water as control. Baseline and serial serum iron samples were drawn to determine pharmacokinetic parameters. RESULTS: A trend toward increased time to peak following sodium polystyrene sulfonate compared to the control arm (5.7 vs 3.6 hours) was observed but was not statistically significant (p = 0.517). A trend toward smaller area-under-the-curve for the sodium polystyrene sulfonate was evident but was not statistically significant (p = 0.77). Iron concentration increased on average 298 mcg/dL and 370 mcg/dL above baseline in the treatment and control arms (p = 0.44). Sodium polystyrene sulfonate is not an effective method of decontamination for iron overdose.

Administration, Oral↗

Absence of cardiac valve dysfunction in obese patients treated with sibutramine.

OBJECTIVE: Serotonin-releasing agents prescribed as weight-loss medications have been implicated as a cause of acquired aortic and mitral valve abnormalities. Sibutramine hydrochloride (MERIDIA) is a serotonin and norepinephrine reuptake inhibitor with proven efficacy of weight reduction. The purpose of this study was to determine the incidence of cardiac valve disease in sibutraminetreated patients. RESEARCH METHODS AND PROCEDURES: Obese patients with type 2 diabetes mellitus enrolled in an ongoing double-blind, placebo-controlled, parallel-arm, 12-month study of sibutramine (followed by a 12-month open label extension) underwent transthoracic echocardiographic imaging and color Doppler interrogation for assessment of cardiac valve anatomy and function. RESULTS: A total of 210 patients were evaluated. Of these, 133 were receiving sibutramine (72 in the double-blind period), and 77 were receiving placebo. The mean+/-Standard Deviation age was 54+/-9 years, and the mean duration of treatment was 229+/-117 days (approximately 7.6 months). The prevalence of left-sided cardiac valve dysfunction was low and similar for the two treatment groups (sibutramine 3/133, or 2.3%; placebo 2/77, or 2.6%). All five cases were cases of aortic insufficiency; four were mild, one was severe (in a placebo patient). All three sibutramine cases were patients over age 50; two had a history of systemic hypertension. CONCLUSION: The prevalence of left-sided cardiac valve dysfunction was not higher than background in obese patients treated with sibutramine for an average of 7.6 months.

Adult↗

Neuronal database integration: the Senselab EAV data model.

We discuss an approach towards integrating heterogeneous nervous system data using an augmented Entity-Attribute-Value (EAV) schema design. This approach, widely used in implementing electronic patient record systems (EPRSs), allows the physical schema of the database to be relatively immune to changes in domain knowledge. This is because new kinds of facts are added as data (or as metadata) rather than hard-coded as the names of newly created tables or columns. Because the domain knowledge is stored as metadata, a framework developed in one scientific domain can be ported to another with only modest revision. We describe our progress in creating a code framework that handles browsing and hyperlinking of the different kinds of data.

Databases, Factual↗

Accidental and suicidal adolescent poisoning deaths in the United States, 1979-1994.

OBJECTIVE: To describe the epidemiological features of poisoning deaths in adolescents in the United States. DESIGN: Descriptive analysis of poisoning deaths in persons aged 10 to 19 years in the United States from January 1, 1979, to December 31, 1994, based on national mortality data. STUDY POPULATION: Adolescents whose cause of death was identified as poisoning using International Classification of Diseases, Ninth Revision codes. MAIN OUTCOME MEASURE: Nature of injury (accident vs suicide). RESULTS: There were 4129 suicides and 3807 accidental deaths due to poisoning. Victims were most frequently male and white. However, poisoning was more often the method of suicide in adolescent girls than in boys (28.0% vs 8.7%). The number of deaths (7138 vs 798) and death rate (2.36 vs 0.28 per 100,000 population) were higher in 15- to 19-year-olds vs 10- to 14-year-olds. The distribution of substances involved was different for 10- to 14-year-olds compared with 15- to 19-year-olds and for suicides compared with accidents. Among 10- to 14-year-olds, drugs other than alcohol accounted for 232 (85.3%) of 272 suicides but only 118 (22.4%) of 526 accidental deaths. Gases and vapors played an important role in accidental deaths and suicides in 15- to 19-year-olds and in accidents in 10- to 14-year-olds. CONCLUSIONS: The rates of suicides and accidental poisoning deaths were lower in 10- to 14-year-olds compared with 15- to 19-year-olds. Areas where injury-prevention efforts might have an influence on adolescent fatalities include management of depression, substance abuse education, and use of carbon monoxide detectors or shutoff switches.

Accidents↗

Streptozotocin-induced diabetes enhances cardiac heparin-releasable lipoprotein lipase activity in spontaneously hypertensive rats.

Vascular endothelial-bound lipoprotein lipase (LPL), also known as heparin-releasable LPL, catalyzes the breakdown of the triglyceride component of lipoproteins and is rate-limiting for free fatty acid transport to tissues. We previously demonstrated that heparin-releasable LPL activity increases in diabetic Wistar rat hearts, whereas with the development of hypertension in spontaneously hypertensive rats (SHR), there is a concomitant and progressive reduction in LPL activity. The objective of the present study was to examine the regulation of cardiac LPL activity in SHR-diabetic rats. Heparin perfusion of the isolated Langendorff heart induced the release of LPL activity. SHR hearts demonstrated a reduction in peak heparin-releasable LPL activity, relative to Wistar controls. However, induction of streptozotocin-induced diabetes in SHR, as in Wistar rats, increased peak heparin-releasable LPL activity in perfused hearts. The elevated heparin-releasable LPL peak could not be accounted for by enhanced LPL synthesis in that both cellular and surface-bound LPL activities in myocytes from SHR-diabetic rats were low relative to control. Chronic (12-day) insulin treatment of SHR-diabetic rats reduced the augmented heparin-releasable LPL activity and increased cell-associated LPL activity. Moreover, acute (90-minute) treatment of SHR-diabetic rats with rapid-acting insulin also reduced the heparin-releasable LPL activity to normal, although it had no effect on the low cellular LPL activity. These results demonstrate that the diabetes-induced augmentation of cardiac LPL counteracts the reduction in enzyme activity associated with hypertension. This may serve to increase the delivery of free fatty acid to the heart, and the resultant metabolic changes may lead to the severe cardiomyopathy observed in the hypertensive-diabetic rat heart.

Animals↗

Prolonged formation of methemoglobin following nitroethane ingestion.

BACKGROUND: Artificial nail removers containing nitroethane pose a serious risk of toxicity when ingested. CASE REPORTS: We report 3 cases of children under 3 years of age who developed prolonged methemoglobinemia following ingestions of small quantities of these nitroethane-containing products. Methylene blue therapy reduced the methemoglobin level in all 3 children; however, in 2 of these children methemoglobin levels increased again several hours later and required additional methylene blue. Accurate substance identification is essential for appropriate management of ingestions of fingernail products. The availability of nitroethane products for home use should be questioned.

Antidotes↗

Relation between bed use, social deprivation, and overall bed availability in acute adult psychiatric units, and alternative residential options: a cross sectional survey, one day census data, and staff interviews.

OBJECTIVES: To examine the relation between bed use, social deprivation, and overall bed availability in acute adult psychiatric units and to explore the range of alternative residential options. DESIGN: Cross sectional survey, combined with one day census data; ratings by and interviews with staff; examination of routine data sources. SETTINGS: Nationally representative sample of acute psychiatric units. SUBJECTS: 2236 patients who were inpatients on census day. MAIN OUTCOME MEASURES: Bed occupancy levels, judged need for continuing inpatient care, reasons preventing discharge, scores on the Health of the Nation outcome scales. RESULTS: Bed occupancy was related to social deprivation and total availability of acute beds (r = 0.66, 95% confidence interval 0.19 to 0.88, F = 8.72, df = 2.23; P = 0.002). However, 27% (603/2215) of current inpatients (61% (90/148) of those with stays of > 6 months) were judged not to need continuing admission. The major reasons preventing discharge were lack of suitable accommodation (37% (176/482) of patients in hospital < 6 months v 36% (31/86) of those in hospital > 6 months); inadequate domiciliary based community support (23% (113) v 9% (8)); and lack of long term rehabilitation places (21% (100) v 47% (40)). Scores on the Health of the Nation outcome scale were generally consistent with these staff judgments. CONCLUSIONS: The shortage of beds in acute psychiatric units is related to both social deprivation and the overall availability of acute beds. Patients currently inappropriately placed on acute admission wards should be relocated into more suitable accommodation, either in hospital or in the community. A range of provisions is required; simply providing more acute beds is not the answer.

Acute Disease↗

Differential effects of streptozotocin-induced diabetes on cardiac lipoprotein lipase activity.

Lipoprotein lipase (LPL) is an endothelial-bound enzyme that is rate determining for the clearance of triacylglycerol-rich lipoproteins. Previous studies using rats with streptozotocin (STZ)-induced diabetes have reported inconsistent effects on cardiac LPL activity or immunoreactive protein. To examine the contribution of the severity and duration of diabetes on cellular and heparin-releasable cardiac LPL activity, Wistar rats were administered a high (100 mg/kg; D100) or moderate (55 mg/kg; D55) dose of STZ, and LPL activity was examined at various times after diabetes induction. Heparin perfusion of the isolated Langendorff control heart induced the release of LPL activity as an initial fast phase followed by a slow phase of release. With increasing age, the second phase of LPL release became more pronounced. Severe STZ-induced diabetes reduced heparin-releasable LPL activity by 1 week in the D100 rats. However, in D55 rat hearts, peak heparin-releasable LPL activity was higher than that in control animals at 2 and 12 weeks after STZ injection, with a complete absence of the delayed phase at 12 weeks. The elevated heparin-releasable LPL peak could not be explained by an enhanced LPL synthesis because both cellular and surface-bound LPL activities in myocytes from D55 rats were low, relative to control. Chronic (12-day) insulin treatment of D55 rats prevented the rise in heparin-releasable LDL and the reduction in cell-associated LPL activity. Moreover, acute (90-min) treatment of D55 rats with rapid-acting insulin also reduced the heparin-releasable LPL activity to normal levels, although it had no effect on the low cellular LPL activity. When the heparin-releasable LPL pool was allowed to recover for 1 h after removal of the enzyme, D55 rat hearts continued to demonstrate a higher peak LPL activity after a second heparin perfusion. These studies demonstrate that in moderate but not severe diabetes, there is an augmented peak heparin-releasable LPL activity. Whether or not this enhanced heparin-releasable LPL activity has a pathological role in the diabetic heart has yet to be determined.

Animals↗

Effects of mental health services reform on clinical practice in the United Kingdom.

In the last few years, the British National Health Service, local government social services departments, the welfare benefits system, and the organization of primary health care in the United Kingdom have undergone major reforms that have had significant effects on mental health services. Local social service departments were given the lead role in purchasing and coordinating community supports for persons with mental illness, but were not given enough funds to arrange adequate services. In the National Health Service, an internal-market approach, in which local health authorities could contract with any provider or group of providers, was introduced. This purchaser-provider split has created a climate of competition in a traditionally collaborative environment and has reduced staff morale. Similar but separate case management models were introduced in both the health service and the social service departments, which has led to inefficiency in planning care for individual patients. Opportunities were created for general practitioners to use capitated funds to purchase specialty care directly from providers. This arrangement resulted in an initial emphasis on care for less severely mentally ill patients, although some general practitioners are beginning to explore new approaches for supporting severely ill patients in the community. On the positive side, the reforms have led to greater involvement of patients and their families in planning service delivery. However, the authors suggest that policy makers in the U.K. seem to be repeating many of the mistakes made by American mental health systems in the 1960s and 1970s.

Cost-Benefit Analysis↗

Residential care in hospital and in the community--quality of care and quality of life.

BACKGROUND: The reduction of beds in long-stay hospitals has led to concerns over the quality of care offered to the remaining residents as well as that provided in the community. This study seeks to compare the quality of care and quality of life (reported satisfaction) from residents in both types of setting. METHOD: A cross-sectional comparison was made of community residential homes and hospital wards drawn randomly from lists provided by local authorities in the outer London area. Samples were drawn from all the main provider types (local authority, housing association, private and joint NHS/voluntary sector). Measures were taken of the quality of the physical environment, staff and resident characteristics, external management arrangements and internal management regimes, resident satisfaction and staff stress. Direct observations were also made of the amount and quality of staff-resident interactions. RESULTS: In general, the most disabled residents were found to be still living in hospital in the Worst conditions and receiving the poorest quality of care. Although there were some problems with missing data, hospital residents also seemed most dissatisfied with their living situation. There were few differences between community providers regarding either the quality of care provided or the levels of reported satisfaction. Quality of care in the community homes seemed to be much more determined by the personality and orientation of project leaders. CONCLUSIONS: Purchasers and providers still need to give attention to the problems of selectively discharging the most able residents to the community, leaving the most disabled being looked after in progressively deteriorating conditions. All residential providers need to review their internal management practices and try to ensure that residents are offered, as far as possible, the opportunity to make basic choices about where and how they will live. Staff training and quality assurance practices need to be reviewed in order to improve the direct quality of care offered to the most disabled individuals.

Activities of Daily Living↗

The 'ward-in-a-house': residential care for the severely disabled.

This paper is concerned with the care of the most difficult and severely disabled new patients presenting to mental health services in the U.K. Questions of definition will be examined and the clinical and social characteristics of the population discussed. Since the defining characteristics (and prevalence) of this group are strongly affected by the overall service context, the range of community provisions within one health district (Cambridge) will be described. Examples of a new kind of institutional solution-the 'ward-in-a-house'-will then be presented, together with the underlying principles of management and care. The benefits and limitations of the model will be discussed.

Activities of Daily Living↗