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Biomedical subjects

S Sandhu

Publications and source records attributed to S Sandhu.

At least 37 records · Page 2Linked to original sources
PubMed1997

Hypoglycaemia-induced inhibition of pulsatile luteinizing hormone secretion in female rats: role of oestradiol, endogenous opioids and the adrenal medulla.

Oestradiol (E2) has been shown to exacerbate the inhibitory effect of hypoglycaemic stress on gonadotrophin-releasing hormone pulse generator (GnRH) activity in primates. The mechanism by which this is mediated is not yet known. We therefore aimed to establish whether there is a sensitizing influence of E2 on the suppression of LH pulsatility in response to hypoglycaemia in the female rat, thus providing a more amenable model in which to study this phenomenon. In ovariectomized Wistar rats with E2 replacement, insulin-induced hypoglycaemia (0.5 U/kg i.v.) resulted in an interruption of pulsatile LH secretion. Induction of the same degree of hypoglycaemia in ovariectomized rats without E2 replacement was without effect on LH pulsatility. Naloxone administration prevented the hypoglycaemia-induced inhibition of LH pulses. Because hypoglycaemia is a potent activator of the sympathetic nervous system, we also tested the hypothesis that the adrenal medulla is involved in this suppression of LH pulses in the rat. Adrenomedullectomy completely prevented this inhibitory response to hypoglycaemic stress. These data are consistent with the hypothesis that E2 sensitizes the GnRH pulse generator to the inhibitory influences of hypoglycaemic stress in the rat. Furthermore, a clear role for both endogenous opioid peptides and the adrenal medulla in the stress-induced suppression of LH pulsatility is identified.

Adrenal Medulla↗
PubMed1996

A double-blind placebo-controlled study to assess the efficacy of a compound analgesic to prevent postoperative pain following oral surgery.

It has been suggested that small doses of opioid drugs given prior to surgery can reduce postoperative pain. This study was designed to compare the effectiveness of a paracetamol/codeine combination and paracetamol alone in preventing the pain following surgical removal of impacted third molar teeth under general anaesthesia. Analysis of the results showed no statistical differences between treatment groups when compared with placebo. We suggest that the opioids may not be the best drugs available to prevent the moderate to severe pain present following some oral surgery procedures.

Acetaminophen↗
PubMed1996

Injury prevention counseling opportunities in pediatric otolaryngology.

OBJECTIVE: To determine the prevalence of injury prevention counseling opportunities in children referred to a pediatric otolaryngologist. DESIGN: A caregiver questionnaire was administered during office registration. SETTING: Hospital-based pediatric otolaryngology practice in a metropolitan area. PATIENTS: Random sample of 300 caregiver questionnaires stratified by the age of the child. MAIN OUTCOME MEASURES: Prevention counseling opportunities, defined as ignorance of hottest water temperature, child exposure to passive smoke, missing smoke detectors on one or more floors in the home, or failure to use a seat belt or bicycle helmet. RESULTS: The hottest water temperature was unknown by 72% of the caregivers, smokers were present in 25% of the households, bicycle helmets were not used by 22% of the children, car seats or seat belts were not used by 11% of the children, and 10% of the homes did not have a working smoke alarm on each floor. Older children were significantly less likely to use a seat belt than were younger children. Although 98% of the caregivers had a regular pediatrician, 91% of the families still offered one or more counseling opportunities (95% confidence interval, 87% to 94%). CONCLUSIONS: Substantial opportunities exist for injury prevention counseling in pediatric otolaryngology. At least one opportunity for counseling is present for about 90% of the families, most often concerning the maximum safe hot water temperature.

Bicycling↗
PubMed1994

Stress management for clinical medical students.

This study evaluates a new stress management course for medical students offered through the Occupational Health Unit, Royal Free Hospital, London. It was offered to students in their first clinical year, which has been shown to be a highly stressful time. The course took place over 3 weeks, with one 2-hour session each week. Students completed questionnaires about mood, attitudes and causes of stress at the beginning of the year, and again one year later. The uptake of this optional course was 17%. Attendees, compared with non-attendees, were more anxious, less satisfied with themselves and their life, and perceived both work and outside functioning to be poorer. Over this first clinical year, non-attendees became significantly more dissatisfied at work and increasingly perceived their functioning at work and outside to be poorer whilst attendees showed no such deterioration over the year. Attendees completed the questionnaires before and after the course, and at two time points prior to starting the course when on the waiting list. Improvements in reported work functioning were found after the course, and this change was significant compared with the waiting list controls. These results are consistent with the attendees' own reports that they found the course helpful. These results show that stress management provides long-term protective effects as well as short-term benefits.

Anxiety↗
PubMed1994

Left ventricular outflow tract obstruction defined by active three-dimensional echocardiography using rotational transthoracic acquisition.

A rotational data acquisition system was used to create three-dimensional images from thoracic and subxiphoid echocardiographic windows in children with various types of subaortic stenosis. Thirteen patients, ranging in age from 2 days to 17 years, were examined. Subaortic obstruction was caused by a discrete fibrous ridge in six patients, hypertrophic cardiomyopathy in two patients, subaortic tunnel in two patients, and septal malalignment, restrictive VSD, and abnormal suture placement each in one patient. Unique views could be obtained equivalent to surgical or autopsy dissections, and allowed more complete understanding of morphology than conventional imaging techniques.

Adolescent↗
PubMed1992

Cardiotoxic effects of astemizole overdose in children.

Astemizole, a nonsedating antihistamine, caused a prolonged corrected QT interval, ventricular dysrhythmias, and atrioventricular heart block after overdose in five children. Cardiotoxic effects lasted an average of 2 1/2 days. Children poisoned with astemizole need emergent medical evaluation, a 12-lead electrocardiogram with calculation of the corrected QT interval, and continuous cardiac monitoring for 24 hours.

Arrhythmias, Cardiac↗
PubMed1992

A double-blind placebo controlled trial of medroxyprogesterone acetate and cyproterone acetate with seven pedophiles.

Seven of ten pedophiles in hospital completed a double-blind, placebo-controlled two-dose comparison of medroxyprogesterone acetate and cyproterone acetate. Sequential measures during the 28 week study were: patient self-reports, nurses' observations, phallometry, hormone levels and side-effects. The drugs, which performed equivalently, reduced sexual thoughts and fantasies, the frequency of early morning erections on awakening, the frequency and pleasure of masturbation, and level of sexual frustration. Penile responses were also reduced but to a lesser degree and were more variable. Serum testosterone FSH and LH all declined during drug administration, but by the end of the final placebo phase had essentially returned to (or exceeded) pre-drug values. Our experience suggests that only a minority of pedophiles are likely to accept libido-reducing drugs.

Adult↗
PubMed1990

The effect of complete and incomplete revascularization on exercise variables in patients undergoing coronary angioplasty.

To investigate the effects of complete and incomplete revascularization on the response to exercise, 25 patients underwent symptom-limited exercise testing with continuous assessment of gas exchange a mean of 5 +/- 4 days prior to and 18 +/- 12 days following percutaneous transluminal coronary angioplasty. All antianginal medications were discontinued for testing. Revascularization was considered complete if all stenoses were reduced to less than 50% diameter (13 patients), and incomplete if one or more stenoses remained (12 patients). Consistent improvements in ST-segment depression were observed after angioplasty at matched submaximal exercise levels (mean range 0.5-0.8 mm; p less than 0.05), and were accompanied by a reduction in angina. Significant increases in heart rate and systolic blood pressure were observed at peak exercise following angioplasty in both groups. Gas exchange variables were significantly improved at maximal exercise, with a similar increase in oxygen uptake observed in both groups following angioplasty (mean increase 3.3-3.7 ml/kg/min; p less than 0.01). Thus, incomplete revascularization following coronary angioplasty resulted in hemodynamic, electrocardiographic, symptomatic, and gas exchange responses to exercise that were comparable to complete revascularization.

Adult↗
PubMed1990

Group anxiety management: effectiveness, perceived helpfulness and follow-up.

An evaluation was conducted on out-patient cognitive-behavioural anxiety management groups. Twenty-nine clients assessed before and after the group and at three-month follow-up showed significant improvement on self-report measures. A further follow-up on 21 clients, conducted by an independent assessor at an average of 11 months, showed greater improvement with time. Clients also rated how helpful they had found non-specific therapeutic factors, and specific anxiety management techniques. 'Universality' was the most helpful non-specific factor, and 'the explanation of anxiety' was the most helpful technique.

Adult↗
PubMed1990

Effect of fructose 1,6-diphosphate infusion on the hormonal response to exercise.

Exogenous fructose 1,6-diphosphate (FDP), a glycolytic intermediate, has recently been demonstrated to accelerate ATP production, prevent glycogen breakdown, stimulate glycogen synthesis, and synthesize free fatty acids in animals and humans. To assess the effects of FDP on the hormonal and metabolic response to exercise, ten trained males (34 +/- 7 yr) underwent 1 h of continuous exercise at 70% VO2max followed by 20 W.min-1 increments to exhaustion. Two hundred fifty mg.kg-1 body weight FDP or placebo was infused in randomized, double-blind, crossover fashion. No differences were observed in heart rate, blood pressure, gas exchange data, perceived effort, or glucose, insulin, free fatty acid, lactate, beta-hydroxybutyrate, glycerol, and glucagon concentration at rest, during exercise, or upon exhaustion. In contrast to the previously reported bioenergetic effects of FDP under conditions in which glycolysis is impeded (acidosis, hypoxia, and ischemia), FDP did not affect the gas exchange, hormonal, or substrate response to moderately high intensity exercise in healthy normals.

Adult↗
PubMed1989

International application of a new probability algorithm for the diagnosis of coronary artery disease.

A new discriminant function model for estimating probabilities of angiographic coronary disease was tested for reliability and clinical utility in 3 patient test groups. This model, derived from the clinical and noninvasive test results of 303 patients undergoing angiography at the Cleveland Clinic in Cleveland, Ohio, was applied to a group of 425 patients undergoing angiography at the Hungarian Institute of Cardiology in Budapest, Hungary (disease prevalence 38%); 200 patients undergoing angiography at the Veterans Administration Medical Center in Long Beach, California (disease prevalence 75%); and 143 such patients from the University Hospitals in Zurich and Basel, Switzerland (disease prevalence 84%). The probabilities that resulted from the application of the Cleveland algorithm were compared with those derived by applying a Bayesian algorithm derived from published medical studies called CADENZA to the same 3 patient test groups. Both algorithms overpredicted the probability of disease at the Hungarian and American centers. Overprediction was more pronounced with the use of CADENZA (average overestimation 16 vs 10% and 11 vs 5%, p less than 0.001). In the Swiss group, the discriminant function underestimated (by 7%) and CADENZA slightly overestimated (by 2%) disease probability. Clinical utility, assessed as the percentage of patients correctly classified, was modestly superior for the new discriminant function as compared with CADENZA in the Hungarian group and similar in the American and Swiss groups. It was concluded that coronary disease probabilities derived from discriminant functions are reliable and clinically useful when applied to patients with chest pain syndromes and intermediate disease prevalence.

Algorithms↗
PubMed1989

Optimal sampling interval to estimate heart rate at rest and during exercise in atrial fibrillation.

To investigate the ideal sampling interval for the estimation of heart rate (HR) at rest and during exercise in atrial fibrillation (AF), maximal exercise testing with continuous electrocardiographic acquisition was performed in 10 patients with chronic AF (mean age 66 +/- 4 years) and 10 subjects in normal sinus rhythm (mean age 31 +/- 6 years). Measurements of HR were obtained at 9 different sampling intervals (1, 2, 3, 6, 10, 15, 20, 30 and 60 seconds) at rest and 7 different sampling intervals (1, 2, 3, 6, 10, 15 and 20 seconds) during the last 30 seconds of each minute during exercise. The HR obtained from each interval was compared with true HR (determined by a 4-minute sample at rest and by the last 30 seconds of each minute during exercise). Among patients with AF, large differences were observed between the HR obtained and true HR, both at rest and during exercise, using small sampling intervals. The mean of these differences ranged between 16 +/- 11 beats/min (range 14 to 22) using 1-second sampling intervals and 2.2 +/- 2.0 beats/min (range 1.6 to 4.4) using 20-second sampling intervals during progressive exercise. Variability of the HR obtained from a given random sample was also high when short sampling intervals were used among patients with AF. These observations were contrasted by subjects in normal sinus rhythm, among whom neither variability nor measurement error were influenced remarkably by changing the sampling interval or increasing HR.

Adult↗
PubMed1989

The effect of cardioversion on maximal exercise capacity in patients with chronic atrial fibrillation.

To evaluate the effect of cardioversion on exercise capacity, 11 male patients (59 +/- 8 years) with chronic atrial fibrillation underwent maximal exercise testing using gas exchange techniques before and after successful cardioversion to normal sinus rhythm. Testing was conducted 1 day prior to and a mean of 39 (range 10 to 95) days following cardioversion. Heart rate, blood pressure, and respiratory gas exchange responses were evaluated at rest, at a standard submaximal workload (3.0 mph/0% grade), at the gas exchange anaerobic threshold, and at maximal exertion. Cardioversion resulted in a mean decrease in resting heart rate of 37 beats/min (113 +/- 16 versus 76 +/- 10 beats/min, p less than 0.001). While mean heart rate was approximately 50 beats/min lower following cardioversion at both submaximal stages of exercise p less than 0.001), oxygen uptake was not different. At maximal exercise, heart rate was markedly reduced (192 +/- 24 to 144 +/- 21 beats/min, p less than 0.001) and maximal oxygen uptake was higher (1.86 +/- 0.5 to 2.06 +/- 0.5 L/min, p less than 0.05) after cardioversion. In addition, an improved efficiency of ventilation was observed at exercise levels exceeding 60% of maximal oxygen uptake.

Aged↗
PubMed1988

Reliability of Bayesian probability analysis for predicting coronary artery disease in a veterans hospital.

To assess the accuracy of Bayesian probability analysis for the prediction of coronary artery disease, post-test probabilities were generated by the application of three Bayesian algorithms to the clinical and noninvasive test results of 199 patients undergoing angiography in a veterans' hospital. All assumed conditional independence but each used different pre-test and conditional probabilities. Two statistical approaches were employed: (1) Sorting of patients in ascending deciles of probability and comparing expected and observed probabilities in each decile. (2) Calculation of normally distributed reliability statistics which do not depend on probability subsets and the comparison of resulting probability distributions using these statistics. Both statistical approaches revealed that the Bayesian algorithms overestimated disease probability when it was high and underestimated it when low. Though all three algorithms were frequently incorrect, they differed significantly in their accuracies, suggesting that errors in Bayesian analysis are caused by factors other than the assumption of independence. The errors may be due to differences in sensitivity and specificity of tests applied in different institutions.

Adult↗
PubMed1986

Rat cerebral cortical estrogen receptors: male-female, right-left.

We determined the concentration of cytosol estrogen receptors in the postnatal, developing right and left cerebral cortices of Long-Evans male or female rats 2 to 3, 7 to 8, 14 to 15, and 25 to 26 days of age. Under anesthesia, the rats were gonadectomized and 24 h later they were killed by decapitation, and the dorsal right and left cerebral cortices were separated from the underlying white matter and placed on ice. Sephadex LH-20 gel filtration chromatography was used to dissociate the majority of alpha-fetoprotein-bound [3H]estradiol while leaving the receptor [3H]estradiol complex intact. The correction for the residual nonreceptor binding, including alpha-fetoprotein, was made using parallel incubation containing unlabeled diethylstilbesterol. The amount of residual nonreceptor binding was subtracted from [3H]estradiol-bound protein to calculate high-affinity estradiol binding receptors. The results showed that in both sexes, estrogen receptor concentration was highest at postnatal days 2 to 3 in both the right and the left cerebral cortex and then decreased until 25 days of age. In the female, the right cerebral cortex, at postnatal day 2 to 3, had a higher estrogen receptor concentration than the left cortex (P less than 0.02). In the male, the left cortex had a higher cytoplasmic estrogen receptor concentration (P less than 0.02) than the right. Considering the reported growth-inhibiting effects of estrogen on the cerebral cortex, the results indicated that one determinant of cerebral dominance in both sexes may be the differential exposure to estrogen, in the case of the male testosterone converted to estrogen, during a critical period of development.

Animals↗
PubMed1984

Enhanced growth and immune development in dwarf chickens treated with mammalian growth hormone and thyroxine.

The effects of growth hormone and/or thyroxine treatments on antibody production, primary lymphoid organ development, and general body growth were examined in two dwarf strains (sex-linked dwarf--SLD, and autosomal dwarf--ADW) and in a normal-growing strain (K) of White Leghorn chickens. One-day-old male chicks were assigned to experimental groups and were treated either with thyroxine (T4) feed supplements or daily mammalian growth hormone (GH) injections or a combination of these treatments (T4/GH). Within the SLD strain, GH treatments resulted in a significant enhancement (P less than 0.005) of humoral immune responsiveness and bursal growth while T4 treatments significantly (P less than 0.05) stimulated thymic growth. Overall growth in the SLD was also stimulated by T4 treatments. GH and/or T4 treatments had no specific effects on primary lymphoid organ growth in the ADW strain but either treatment separately resulted in a significant (P less than 0.05) increase in overall body size. None of the treatments significantly (P greater than 0.05) affected any of these parameters in the K-strain controls. Supplementation with T4 significantly elevated serum T4 levels within all strains. There were, however, no significant differences in the serum levels of T4 between strains within any of the treatment groups. Serum triiodothyronine (T3) levels were significantly lower in all treatment groups of the SLD as compared to the K-strain control. ADW serum T3 levels were significantly lower than the K-strain only in the T4-treated group. No differences (P greater than 0.05) were found between the dwarf and control strains in endogeneous GH levels, although mammalian GH treatments did produce significant changes in serum T3 and T4 levels within the K-strain. These results provide evidence that hormonal manipulations can significantly affect body growth, primary lymphoid organ development, and immune function in the dwarf strains studied and suggest these strains may be useful models for future studies on hormonal interactions and immune function.

Animals↗