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Biomedical subjects

S W Turner

Publications and source records attributed to S W Turner.

At least 37 records · Page 2Linked to original sources
PubMed1999

Haemodynamic mechanisms of corticotropin (ACTH)-induced hypertension in the rat.

OBJECTIVES: To investigate the roles of cardiac output and systemic and regional resistances in corticotropin (ACTH)-induced hypertension in the rat METHODS: This study consisted of three series of experiments with eight groups of male Sprague-Dawley rats (n = 132). Series 1 comprised groups 1-4, where group 1 = sham (0.9% NaCl, subcutaneous (s.c.) injection); group 2 = ACTH (0.5 mg/kg per day, s.c.); group 3 = atenolol + sham; group 4 = atenolol + ACTH treatments. Series 2 comprised groups 5 and 6, where group 5 = minoxidil + sham and group 6 = minoxidil + ACTH treatments. Series 3 comprised groups 7 and 8, where group 7 = ramipril + sham and group 8 = ramipril + ACTH treatments. Systolic blood pressure, water and food intakes, urine volume, and body weight were measured every second day. After 10 days of treatment, mean arterial blood pressure was measured by intra-arterial cannulation, and cardiac output (CO), and renal, mesenteric and hindquarter blood flows (RBF, MBF and HBF) determined using transonic small animal flowmeters. RESULTS: ACTH treatment increased blood pressure (P < 0.001) with a rise in CO (P < 0.01) and renal vascular resistance (RVR, P < 0.05), but did not affect total peripheral resistance (TPR). Atenolol blocked the rise in CO without affecting the rise in blood pressure produced by ACTH treatment Minoxidil lowered TPR, but did not prevent the rise in blood pressure or renal vascular resistance. Ramipril blunted the rise in RVR and blood pressure without significantly affecting TPR. CONCLUSION: Neither preventing rise in CO nor lowering TPR altered the ACTH-induced rise in blood pressure in the rat However, both the hypertension and rise in RVR were prevented by ramipril. These data suggest that increase in RVR may play a role in the pathogenesis of ACTH-induced hypertension in the rat.

Adrenocorticotropic Hormone↗
PubMed1999

The natural history of ventricular septal defects.

AIMS: To correlate the size and position of isolated ventricular septal defects with closure rate in a cohort of children with mean follow up of more than six years. DESIGN: A birth cohort was identified using the northern region cardiac database. The following were noted from case notes: defect size, position, means of closure, and age at closure. RESULTS: 68 children were identified. 49 defects were small, 14 were moderate, and 5 were large. 13 cases required surgical closure, including 12 perimembranous defects. 35 defects closed spontaneously. Nine of the small muscular defects remained open and five of the small perimembranous defects remained open. The spontaneous closure rate for muscular defects was significantly greater than for perimembranous defects. Mean age of follow up for patients who still have defects is 76 months. CONCLUSIONS: The position of a ventricular septal defect is extremely relevant to its natural history. Perimembranous defects accounted for most of the moderate and large defects that required surgical intervention. After more than six years almost a third of all perimembranous and just over two thirds of all muscular defects closed spontaneously.

Child, Preschool↗
PubMed1999

The role of the parathyroid glands in adrenocorticotrophin-induced hypertension in the rat.

The aim of this study was to determine whether parathyroidectomy (PTx) would modify hypertension secondary to adrenocorticotrophin (ACTH) administration. Male Sprague Dawley (SD) rats were randomly assigned to one of five groups; (i) sham (saline) treatment (NaCl 0.9% s/c 0.5 ml/kg/day), (ii) ACTH treatment (Synacthen Depot 0.5 mg/kg/day), (iii) saline/PTx/1% CaCl2 in water, (iv) ACTH/PTx/1% CaCl2 in water and (v) ACTH/1% CaCl2 in water. Tail cuff systolic blood pressure (SBP) and metabolic parameters were measured on alternate days for 4 control (C) and 11 treatment days (T0-T10). There was no change in SBP in the sham and saline/PTx/CaCl2 groups over T0-10. SBP increased in the ACTH treated groups. PTx did not modify ACTH-induced increases in SBP or metabolic effects. These results do not support a role for the parathyroids in the genesis of ACTH-induced hypertension in the rat.

Adrenocorticotropic Hormone↗
PubMed1998

Adrenocorticotrophin dose-response relationships in the rat: haemodynamic, metabolic and hormonal effects.

OBJECTIVE: To determine adrenocorticotrophin dose-response relationships for increase of blood pressure and metabolic parameters of the Sprague-Dawley rat. METHODS: We injected 120 male Sprague-Dawley rats twice daily subcutaneously for 10 days with 0.5, 1, 5, 50, 100, 200 or 500 microg/kg synthetic adrenocorticotrophin per day (all n = 10) or subjected them to sham injection (0.9% NaCl; n = 50). Systolic blood pressure, 24 h food intake, water intake, urine volume and body weight were measured. Data from a further 45 rats treated with 500 microg/kg per day adrenocorticotrophin in previous studies were included in the blood pressure analyses. After we had killed these rats, their organ weights (kidney, heart, adrenal) and plasma electrolyte, adrenocorticotrophin and serum corticosterone concentrations were measured. RESULTS: On the final day of treatment systolic blood pressure of sham-injection control rats was 123 +/- 1 mmHg (n = 50). Compared with sham treatment, a low dose of adrenocorticotrophin (1 microg/kg per day) increased systolic blood pressure from 122 +/- 1 to 130 +/- 2 mmHg (P < 0.001) without any metabolic effects, whereas a high dose of adrenocorticotrophin (500 microg/kg per day) increased systolic blood pressure from 121 +/- 1 to 150 +/- 2 mmHg (P < 0.001, n = 55) with increases in intake of water and urine volume (P < 0.001, n = 10) and a decrease in body weight (P < 0.001, n = 10). Plasma adrenocorticotrophin and serum corticosterone concentrations for the sham-injection control group were 162 +/- 12 pg/ml (36 +/- 3 pmol/l) and 376 +/- 18 ng/ml (1038 +/- 50 nmol/l), respectively. Plasma adrenocorticotrophin concentration was elevated by injections of 100 (P < 0.05), 200 (P < 0.01) and 500 microg/kg adrenocorticotrophin per day (P = 0.001). Serum corticosterone concentration was not significantly different from that of sham-injection rats with 0.5-5 microg/kg adrenocorticotrophin per day but was increased by injection of 50-500 microg/kg adrenocorticotrophin per day (P < 0.001). CONCLUSIONS: These results define 1 microg/kg adrenocorticotrophin per day, administered subcutaneously, as the threshold dose for causing a rise in blood pressure in the rat Thus administration of adrenocorticotrophin increases systolic blood pressure at doses that induce minimal adrenocorticotrophin metabolic effects. Administration of a low dose of adrenocorticotrophin to the rat is a suitable model for stress-induced hypertension.

Administration, Cutaneous↗
PubMed1997

Preferential glial cell attachment to microcontact printed surfaces.

Microcontact printing is introduced as a method for fabricating test surfaces for attachment of cells to chemically patterned silicon surfaces. Tests with astroglial cells indicate that cells attach to microcontact printed surfaces similarly to surfaces produced by traditional photolithographic methods. Astroglial cells attach selectively to 50 microns wide bars of N1[3-(Trimethoxysilyl)propyl]diethylenetriamine (DETA) self-assembled monolayers (SAMs) on surfaces prepared using variable width spaces generated from microcontact printing with octadecyltrichlorosilane (OTS) as the ink. Our results demonstrate that microcontact printing provides an effective and rapid method for routine production of patterned self-assembled monolayers that can be used for directing cell attachment and studying cell morphology.

Amines↗
PubMed1996

Angiotensin converting enzyme inhibition and protein restriction in progression of experimental chronic renal failure.

This study examined whether the effects of protein restriction and angiotensin converting enzyme (ACE) inhibition on the progression of renal failure are common or additive. Male Sprague Dawley rats (12 wks of age) underwent 5/6 nephrectomy and were randomized to 20% protein diet (PD) (n = 9), 20% PD+enalapril (5 mg/kg/day) (n = 10), 20% PD+felodipine (30 mg/kg/day) (n = 9), 6% PD (n = 9), 6% PD+enalapril (n = 9) or 6% PD+felodipine (n = 10). Protein restriction, enalapril or felodipine treatment all retarded progression of renal failure and development of glomerular lesions. Protein restriction and enalapril appeared to have additive effects in preventing glomerular sclerosis.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

L-arginine prevents corticotropin-induced increases in blood pressure in the rat.

In this study we examined whether L-arginine treatment could prevent corticotropin (ACTH)-induced increases in blood pressure in the Sprague-Dawley rat. Sixty rats were randomly divided into six groups (n = 10): sham injection, ACTH injection (0.5 mg/kg per day in divided doses), L-arginine (0.6%) in food plus sham injection, L-arginine plus ACTH treatment, D-arginine (0.6%) in food plus sham injection, and D-arginine plus ACTH. Systolic pressure, water intake, urine volume, body weight, plasma and urinary electrolytes, and serum corticosterone concentrations were measured. ACTH increased systolic pressure (from 127 +/- 2 to 165 +/- 6 mm Hg, P < .001), water intake, and urine volume and decreased body weight body weight. L-Arginine reduced ACTH-induced blood pressure rises (130 +/- 3 mm Hg, P < .001) but had no effect on blood pressure in sham-treated rats. D-Arginine did not affect blood pressure in sham-treated rats, and systolic pressure in D-arginine+ACTH-treated rats was similar to that of ACTH-treated rats. L-Arginine decreased serum corticosterone concentrations in sham-treated rats (424 +/- 42 versus 238 +/- 25 ng/mL, P < .01), but D-arginine had no effect. However, both drugs decreased serum corticosterone concentrations in ACTH-treated rats (1071 +/- 117 versus 739 +/- 95 and 695 +/- 72 ng/mL for L- and D-arginine, respectively; both P < .05). As L-arginine but not D-arginine prevented ACTH-induced increases in blood pressure in Sprague-Dawley rats and both L- and D-arginine reduced serum corticosterone concentrations in ACTH-treated rats, the effects of L-arginine in preventing ACTH-induced hypertension were not simply a consequence of decreased corticosterone secretion.

Adrenal Glands↗
PubMed1995

The Kings Cross fire: psychological reactions.

The psychological reactions of 50 survivors of the King's Cross fire, which hit London's underground railway system on the 18th day of November 1987, are described. Results are presented for the Impact of Event scale, the General Health Questionnaire (28-item version), the Eysenck Personality Questionnaire and a King's Cross Event Schedule. These are investigated in relation to (a) validity measures, (b) relationships between exposure and personality, and (c) spontaneous de-briefing. Two thirds of the sample had significant levels of psychological distress (meeting the "caseness" criterion on the GHQ). Both personality (neuroticism and L-scale) and degree of trauma exposure were related to subsequent reaction. Spontaneous debriefing was associated with subjective benefit. Transportation disasters present particular problems in relation to research and service delivery.

Adaptation, Psychological↗
PubMed1995

Long-term ouabain administration does not alter blood pressure in conscious Sprague-Dawley rats.

1. We tested the ability of ouabain to cause chronic hypertension by continuously infusing ouabain for 28 days (miniosmotic pump implantation; i.p.). The blood pressure and metabolic effects of sham (150 mmol/L NaCl; n = 12) or ouabain infusion (10 micrograms/kg per day; n = 14; 100 micrograms/kg per day; n = 14) were examined in conscious Sprague-Dawley rats. 2. Plasma ouabain concentrations measured after 28 days of ouabain infusion were as follows: sham, not detectable (n = 11); ouabain 10 micrograms/kg per day, 0.60 +/- 0.07 nmol/L (n = 14); and ouabain 100 micrograms/kg per day, 7.17 +/- 0.57 nmol/L (n = 14; P < 0.001). 3. Sham or ouabain infusion did not alter food intake, bodyweight, water intake or urine output in conscious rats. 4. Blood pressure was not altered by sham treatment. Ouabain at 10 micrograms/kg per day or 100 micrograms/kg per day did not produce consistent rises in blood pressure. Ouabain at 10 micrograms/kg per day increased blood pressure on treatment day 12 only (+6 mmHg; P < 0.05), while at 100 micrograms/kg per day blood pressure increased on treatment days 16 (+9 mmHg; P < 0.05) and day 18 (+8 mmHg; P < 0.05) only. There was no significant difference in blood pressure between sham and ouabain groups. 5. Renal blood flow was decreased in rats infused with ouabain at 10 micrograms/kg per day (2.0 +/- 0.3 mL/min per 100 g bodyweight; n = 5; P < 0.01) and 100 micrograms/kg per day (2.2 +/- 0.4 mL/min per 100 g bodyweight; n = 7; P < 0.05) compared with sham treatment (3.5 +/- 0.2 mL/min per 100 g bodyweight; n = 6). Renal vascular resistance was increased in rats treated with ouabain at 10 micrograms/kg per day (65.5 +/- 12.6 mmHg/mL per min per 100 g bodyweight; n = 5; P < 0.01) and 100 micrograms/kg per day (66.0 +/- 15.6 mmHg/mL per min per 100 g bodyweight; n = 7; P < 0.05) compared with sham treatment (32.6 +/- 2.5 mmHg/mL per min per 100 g bodyweight; n = 6). 6. High plasma concentrations of ouabain do not cause consistent increases in blood pressure in conscious Sprague-Dawley rats.

Animals↗
PubMed1995

An open trial of exposure therapy based on deconditioning for post-traumatic stress disorder.

Twenty-three patients who had experienced a major stressful event were given a debriefing session followed by eight weekly sessions of imaginal exposure and in vivo exposure. Patients recounted their traumatic experiences aloud, using the first person and the present tense, and included as much detail as possible. This account was audiotaped and patients were asked to listen to the tape between treatment sessions. There were reductions of 42 percent in the Impact of Events Scale (IES), of 61 percent in the General Health Questionnaire (GHQ), of 38 percent in the Symptom Checklist-90 (SCL-90) questionnaire, and of 35 percent in the Clinician Administered Post-Traumatic Stress scale (CAPS), all of which were statistically significant. The number of patients who satisfied the diagnostic criteria for post-traumatic stress disorder was halved.

Adult↗
PubMed1995

Assessment and treatment approaches for survivors of torture.

BACKGROUND: Torture, with its personal, cultural, political and psychosocial effects, is presented as a complex trauma. The efficacy of different treatment modalities for those survivors who need assistance is examined critically. METHOD: International literature searches using MEDLINE and Psych-Info, books and relevant book chapters were examined. RESULTS: One hundred and twenty-five articles were selected for analysis; 30 of the most relevant are discussed. CONCLUSIONS: Discrete approaches to treatment have been developed, but many have yet to be evaluated critically. Common therapeutic elements are outlined. It is recommended that an integrated, flexible, client-centred approach utilising several techniques is most likely to achieve best results. Wider socio-political aspects should be taken into account, and treatment must be consistent with cultural expectations. Future directions for research are outlined and the role of primary prevention is stressed.

Combined Modality Therapy↗
PubMed1994

Estimating numbers of homeless and homeless mentally ill people in north east Westminster by using capture-recapture analysis.

OBJECTIVES: To use routinely collected data to provide a reliable estimate of the size and psychiatric morbidity of the homeless population of a given geographical area by using capture-recapture analysis. DESIGN: A multiple sample, log-linear capture-recapture method was applied to a defined area of central London during 6 months. The method calculates the total homeless population from the sum of the population actually observed and an estimate of the unobserved population. Data were collected from local agencies used by homeless people. SUBJECTS: Homeless people in north east Westminster residing in bed and breakfast accommodation and hotels or sleeping rough who had contacted statutory or voluntary agencies in the area. RESULTS: 2150 contacts by 1640 homeless people were recorded. The estimated unobserved population was 3293, giving a total homeless population for the period of around 5000 (SD 1250). Mental health problems were significantly less prominent in the unobserved compared with the observed population (23% (754) v 40% (627), P < 0.0001). For both groups the prevalence varied greatly with age and sex. CONCLUSIONS: Capture-recapture techniques can overcome problems of ascertainment in estimating populations of homeless and homeless mentally ill people. Prevalences of mental illness derived from surveys that do not correct for ascertainment are likely to be falsely inflated while at the same time underestimating the total size of the homeless mentally ill population. Population estimates derived from capture-recapture techniques may usefully provide a good basis for including homeless populations in capitation calculations for allocating funds within health services.

Adult↗
PubMed1994

Effects of dietary magnesium on blood pressure and vascular lesions in hypertensive rats.

The present study examines the effects of dietary magnesium on the development of hypertension and hypertensive vascular lesions in deoxycorticosterone acetate and salt induced (DOCA-salt) and 2 kidney one clip (2K1C) hypertensive as well as normotensive control rats. Animals received a regular (0.12% Mg), high (0.4% Mg) or low (0.03% Mg) magnesium diet for 6 wks. Dietary magnesium did not alter the growth or blood pressure in control, DOCA-salt and 2K1C rats even though the plasma magnesium concentration was significantly altered by the diets (ANOVA, p < 0.05 in control, DOCA-salt and 2K1C, respectively). Dietary magnesium did not alter the urinary potassium excretion, plasma sodium, potassium, total calcium concentration and plasma renin activity in any group, while the high magnesium diet significantly increased the urinary sodium excretion in DOCA-salt (p < 0.05) but not in control and 2K1C rats when compared with the regular magnesium diet. In histological studies, dietary magnesium did not alter the percentage media area of intramyocardial arteries, or glomerular and renal arterial and arteriolar lesions in DOCA-salt and 2K1C rats. This study suggests that moderate alterations of dietary magnesium do not modify blood pressure in normotensive control, DOCA-salt and 2K1C hypertensive rats, nor do they modify vascular disease in these 2 hypertensive models.

Animals↗
PubMed1994

Cyclosporin hypertension in the Wistar rat: role of uninephrectomy.

1. The effects of cyclosporin A (CyA) solution (1-50 mg/kg per day), CyA powder (5-20 mg/kg per day) and vehicle, and the effects of renal mass reduction on CyA induced hypertension, were examined in conscious Wistar rats. 2. CyA solution consistently increased blood pressure at 5-20 mg/kg per day and the powder at 10-20 mg/kg per day. The vehicle had no consistent effect. 3. Both CyA solution and powder inhibited gain in bodyweight. There was no consistent effect on food intake, water intake or urine volume. Plasma sodium (Na+), and Na+ and potassium (K+) excretion were reduced by CyA 20 mg/kg per day. 4. Renal function was impaired by CyA powder at 20 mg/kg per day and plasma renin activity (PRA) was increased by all doses of CyA powder. 5. Thus, uninephrectomy did not potentiate CyA solution (5 mg/kg per day) induced increases in blood pressure and the effects of CyA do not appear to be a consequence of nephrotoxicity in Wistar rats.

Animals↗
PubMed1991

Detention of British citizens as hostages in the Gulf--health, psychological, and family consequences.

OBJECTIVE: To describe the physical, psychological, and family consequences of the detention of British subjects as hostages in Kuwait or Iraq, or both, after the invasion of Kuwait on 2 August 1990 and to investigate the relation between types of trauma experienced and these reactions. DESIGN: Postal questionnaire. SUBJECTS: 381 respondents. RESULTS: Many health, social, and psychological sequelae were identified. Problems with present finance, accommodation, and work are important causes of distress. Many hostages coped well and gained self esteem. CONCLUSIONS: A minority of respondents require further support and treatment. Expatriates in risk areas should retain assets in their home country.

Adult↗
PubMed1991

High-performance liquid chromatographic (HPLC) determination of lobenzarit in plasma and its application to a bioavailability study in beagle dogs.

A method for the quantitative determination of lobenzarit (2-[(2-carboxyphenyl)amino]-4-chlorobenzoic acid) in dog plasma by high-performance liquid chromatography with UV detection (308 nm) is described. Plasma samples (200 microliters) were treated with acetonitrile and centrifuged, and the clear supernatant injected onto a reversed-phase phenyl column. The method achieved a limit of quantitation of 0.5 micrograms/ml in plasma, and the response was linear to 100 micrograms/ml. Comparing a solution and a tablet formulation given to beagle dogs, the assay demonstrated that the solution formulation was slightly more bioavailable and yielded a more variable absorption rate. The elimination of lobenzarit from plasma followed a biexponential time course, with an apparent terminal disposition half-life of between 5.8 and 10.7 hr.

Animals↗