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Biomedical subjects

S G Parker

Publications and source records attributed to S G Parker.

At least 19 recordsLinked to original sources
PubMed1998

Nutritional status of hospitalized acute stroke patients.

The nutritional status of 201 hospitalized stroke patients was assessed from anthropometric, haematological and biochemical data in an observational prospective study. On admission, sixty-two (31%) stroke patients had BMI < 20, ninety-nine (49%) had a triceps skinfolds thickness below the 25th centile, twenty-five (12%) had a mid-arm circumference below the 25th centile and thirty-eight (19%) had a serum albumin concentration below 35 g/l. Baseline nutritional status was worse among those who later died or remained in hospital compared with those discharged and most patients who remained in hospital showed marked and significant deterioration in all measures of nutritional status within 4 weeks of hospitalization. After adjusting for age, stroke severity and co-morbidity, low serum albumin concentrations of these patients in hospital were a strong and independent predictor of death following acute stroke (odds ratio 1.13 (95% CI 1.01-1.27) for 1 g/l lower serum albumin concentration).

Aged↗
PubMed1998

Measuring health status in older patients. The SF-36 in practice.

OBJECTIVE: To examine the use of the Medical Outcomes Study short form 36-item (SF-36) health status measure in older patients receiving health care; to explore the influence of age and physical and cognitive status on response to and completion of the SF-36 questionnaire. DESIGN: Prospective observational study. SETTINGS: Hospital and ambulatory patients aged 65 years and over in the medical and surgical wards and outpatient department of a teaching hospital and a local general practitioner's surgery. SUBJECTS: 1014 hospital inpatients, 80 hospital outpatients and 40 patients attending their general practitioner's surgery. MAIN OUTCOME MEASURES: Response rates, overall rates of completion (sufficient to calculate a valid SF-36 score) and completion of individual questions. RESULTS: 37 out of 40 ambulatory patients in general practice (93%) and 71 out of 80 outpatients (89%) returned a self-completed questionnaire. In hospital inpatients the overall response rate was only 46% (369 of 802). This was improved by interview administration to 77.4% (164 of 212). Logistic regression analysis revealed that self-completion, cognitive dysfunction, disability and age were all independently associated with poor overall response rates. Among those patients who returned a completed questionnaire, completion of individual questions sufficient to calculate a valid score was variable. Only 62.5% of inpatients who self-completed a questionnaire gave sufficient response to calculate a score on the mental health subscale, compared with 93.7% of general practice patients. CONCLUSION: The self-administered questionnaire is unacceptable for older hospital inpatients. Use of an interviewer improves response, but factors which influence health status, such as physical and cognitive dysfunction, have a significant effect on response rates. Therefore the utility of the SF-36 in its present form as a routine health status measure for use in older hospital inpatients is questioned.

Aged↗
PubMed1998

Influence of nutritional status on clinical outcome after acute stroke.

A cause-and-effect relation between protein-energy malnutrition and poor outcome in acute stroke patients has not been definitively established. To measure the effect of the nutritional status of hospitalized stroke patients on clinical outcome, a prospective, observational study was performed. Acute stroke patients admitted to Leicester General Hospital from June 1994 to October 1995 had their nutritional status assessed with anthropometric, hematologic, and biochemical methods within 48 h of admission and after 2 and 4 wk. Outcome measures including disability, handicap, length of stay, morbidity (infective complications), discharge destination, and mortality were recorded during the hospital stay and at 3 mo. Nutritional status deteriorated significantly during the study period, but only serum albumin concentrations showed a significant association with various outcome measures. Stroke patients with hypoalbuminemia had a greater risk of infective complications (P<0.0001) and poor functional outcome during hospitalization than those with normal or higher serum albumin concentrations. Serum albumin concentrations were good predictors of the degree of disability and handicap during the hospital stay. After prognostic indicators of poor outcome were adjusted for, serum albumin concentration in the hospital was a strong and independent predictor of mortality at 3 mo after acute stroke [hazard ratio 0.91 (95% CI: 0.84, 0.99) for a 1-g/L higher serum albumin concentration]. Whether nutritional supplementation removes or mitigates the hazard of poor outcome associated with undernutrition after acute stroke needs to be determined.

Acute Disease↗
PubMed1997

Comparison of the cardiovascular effects of the novel 5-HT(1B/1D) receptor agonist, SB 209509 (VML251), and sumatriptan in dogs.

The systemic cardiovascular effects of a novel 5-hydroxtryptamine (5-HT)(1B/1D)-receptor agonist were investigated in the anaesthetised dog. SB 209509 (VML 251) was more potent than sumatriptan in producing increases in carotid vascular resistance after intravenous administration and was similar in potency to sumatriptan after sequential intraduodenal administration at 30-min intervals. In open-chest dogs, sequential intravenous administration of SB 209509 or sumatriptan produced marked increases in carotid vascular resistance without changing coronary vascular resistance. In contrast to sumatriptan, after administration of high doses of SB 209509 (>790 nmol/kg), a reduction in coronary vascular resistance was observed. After a single bolus intraduodenal dose of SB 209509 (260, 520, or 790 nmol/kg), increases in carotid vascular resistance could be detected over a 5-h period. Sumatriptan (i.d.), 2.4 micromol/kg but not 700 nmol/kg, produced a sustained effect similar to the effects of SB 209509 (790 nmol/kg). In all experiments, SB 209509 and sumatriptan had minimal effects on arterial blood pressure or heart rate but produced marked changes in carotid vascular resistance over the same concentration range. SB 209509 was rapidly absorbed after intraduodenal administration in conscious dogs and had good bioavailability. These data indicate that SB 209509 is a potent 5-HT(1B/1D)-receptor agonist that is rapidly absorbed from the duodenum. The effects of SB 209509 are long lasting and selective for the carotid vascular bed.

Animals↗
PubMed1996

Effect of treatment with calcium antagonists in vitro and in vivo on the contractile response of isolated rat and human detrusor muscle.

1. The effect of calcium antagonists on the contractile response of human and rat isolated detrusor muscle in vitro was investigated. The effect of treatment with nimodipine on rat detrusor muscle in vivo was also examined. 2. Nimodipine 0.1 mumol/l, nifedipine 0.1 mumol/l, nifedipine 0.25 mumol/l and verapamil 1.5 mumol/l reduced the maximum contractile response of isolated human detrusor muscle to carbachol by 42%, 35%, 41% and 28% respectively (P < 0.01). Verapamil 0.1 mumol/l had no significant effect on contractile response. 3. Nimodipine 0.1 mumol/l reduced the maximum contractile response of isolated rat detrusor muscle in vitro to electrical field stimulation and carbachol by 53% and 84% respectively (P < 0.01). 4. Rats were pretreated with nimodipine for 8 days (5 mg day-1 kg-1) or with a single dose. Serum nimodipine concentrations were higher in rats treated for 8 days. In rats treated with nimodipine for 8 days there was no significant difference in detrusor contractile response compared with controls. However, after one dose of nimodipine the maximum contractile response was significantly reduced compared with controls (P < 0.05). 5. At the concentrations studied, nimodipine had a greater inhibitory effect on the contractile response of isolated human detrusor muscle. Nimodipine significantly reduced the contractile response of rat detrusor muscle in vitro and after a single dose in vivo, but had no significant effect after 8 days' treatment in vivo. It is possible that chronic oral treatment with nimodipine caused an up-regulation of 1,4-dihydropyridine-sensitive calcium channels, which may explain the lack of clinical effect of chronic treatment with calcium antagonists in patients with detrusor instability.

Animals↗
PubMed1996

The knowledge of hospital patients about vascular diseases and their risk factors.

The knowledge of 28 stroke patients on the nature, consequences, treatment and risk factors of stroke and ischaemic heart disease was examined using a questionnaire and compared with that of 26 patients with ischaemic heart disease and 41 controls without evidence of vascular disease. Information was also collected on the patients' willingness to change their life-style, the information and advice they had received and their desire for more information. It was found that about half of the elderly stroke and heart disease patients had a reasonable knowledge of the condition and its related risk factors. Only eight (14%) patients remembered receiving information and advice in relation to their condition during their hospital stay compared with one (2%) control. There was a significant difference between the number of stroke and heart disease patients who wanted to know more about their condition compared with the control group (32 vs 14; p = 0.03). A quarter of the patients and half of the controls knew that fruit and vegetables were good for you and excessive fat and alcohol were less inducive to good health. Most patients with a risk factor were willing to exercise more, stop smoking, cut down on their drinking, or lose weight. These results suggest that elderly hospital patients have a reasonable basic knowledge about vascular diseases, but that a significant number want to know more and would be willing to change their life-style.

Aged↗
PubMed1995

Blockade of human and porcine myocardial 5-HT4 receptors by SB 203186.

We investigated the blockade of the positive inotropic effects of 5-hydroxytryptamine (5-HT) by SB 203 186 (piperidinoethyl-indole-3-carboxylate hydrochloride) and its affinity for 5-HT4 receptors of human right atrium and piglet left atrium. We also compared the blocking effects of SB 203 186 against 5-HT-evoked tachycardia in anaesthetised adult Yucatan minipigs as well as new-born Camborough piglets. SB 203 186 caused competitive antagonism of the positive inotropic effects of 5-HT in electrically paced atrial preparations of man (pKB = 8.9) and piglet (pKB = 8.5) at concentrations (up to 0.3 micromol/l) which were devoid of depressant or stimulant effects. The affinity of SB 203 186 for atrial 5-HT4 receptors was 30-160 times higher than that of tropisetron. 5-HT caused tachycardia with similar potency and efficacy in Yucatan minipigs and new-born Camborough piglets. SB 203 186 (0.1-3 mg/kg, i.v.) surmountably antagonised 5-HT-evoked tachycardia in anaesthetised Yucatan minipigs or new-born Camborough piglets with similar potency. The blocking potency of SB 203 186 in Yucatan minipigs was 17 times higher than that of tropisetron. Intraduodenally administered SB 203 186 (0.3-3 mg/kg) to new-born Camborough piglets produced blockade of 5-HT-evoked tachycardia which was maximal after 20 min and lasted for more than 3 h with 0.3 mg/kg. The antagonism produced by the SB 203 186 administration in new-born Camborough piglets was dose-related and threefold greater through the intravenous route than through the intraduodenal route. We conclude that SB 203 186 is an antagonist with nanomolar affinity for both human and porcine atrial 5-HT4 receptor. The in vivo results demonstrate that the sinoatrial 5-HT4 receptors function is similar in new-born Camborough piglets and adult Yucatan minipigs. Both porcine breeds are valid models for human atrial 5-HT4 receptors as demonstrated with the antagonist SB 203 186.

Adult↗
PubMed1995

Production of eicosanoids and cytokines by Kupffer cells from young and old rats stimulated by endotoxin.

1. The clinicopathological features of endotoxaemia have been ascribed to cytotoxic mediators such as tumour necrosis factor, interleukins and eicosanoids. Macrophages, particularly Kupffer cells, are an important source of these mediators. Mortality from endotoxaemia is highly age related. 2. These studies focus on the role of hepatic Kupffer cells in the increased sensitivity of old rats to bacterial endotoxins. Possible age-related changes in the production of eicosanoids and induction of gene expression and secretion of interleukin 1, tumour necrosis factor and interleukin 6 were investigated in Kupffer cells derived from both young and old animals. 3. Basal production of biological response modifiers was low in cells of both young and old rats. Lipopolysaccharide stimulated production of the same types of monokines as described for other types of macrophages, although the pattern was specific for Kupffer cells. 4. Eicosanoids, predominantly prostaglandin D2 and prostaglandin F2 alpha, were produced mainly during the first hour after exposure to lipopolysaccharide. Endotoxin stimulated synthesis of mRNAs of interleukin 1, interleukin 6 and tumour necrosis factor alpha resulting in increased secretion of these cytokines into the medium. 5. Kupffer cells from both young and aged animals appear to be exquisitely sensitive to endotoxin in respect of expression of mRNA for both interleukin 1 alpha and interleukin 1 beta and less sensitive with respect to interleukin 6 and tumour necrosis factor alpha gene expression. At relatively high lipopolysaccharide concentrations interleukin 6 was secreted in particularly large amounts. 6. The effects of ageing on any of these responses of Kupffer cells were minimal.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1994

Tolerance to peripheral, but not central, effects of ropinirole, a selective dopamine D2-like receptor agonist.

Studies were conducted to determine possible development, and underlying mechanisms, of tolerance to the hypotensive effects of ropinirole (4-[2-(dipropylamino)ethyl]-1-3-dihydro-2H-indol-2-one HCl), a selective dopamine receptor agonist, following twice daily oral administration to cynomolgus monkeys and spontaneously hypertensive rats (SHR). Tolerance to the hypotensive effects of the compound developed in both species within one week of repeated dosing. Tolerance which developed in rats was dose-related and could not be attributed to altered plasma/drug concentrations or be overcome by increasing the i.v. challenge dose of ropinirole. Cross-tolerance was shown to the dopamine receptor agonist bromocriptine. Similar hypotensive responses to bethanidine were seen in rats treated with ropinirole or vehicle. Tolerance to hypolocomotor effects of the compound were not apparent in the same time frame. The dopamine D2 receptor antagonist, domperidone, caused hypertension in ropinirole-but not vehicle-treated rats. Results reported in this paper are not consistent with a down-regulation of peripheral dopamine D2-like receptors but suggest a compensatory increase in basal sympathetic tone.

Administration, Oral↗
PubMed1993

Effects of 6-hydroxydopamine on pre- and post-junctional 5-HT1-like receptor-mediated responses in dog saphenous vein.

To investigate whether 5-HT1-like receptor-mediated inhibition of adenosine 3':5'-cyclic monophosphate (cyclic AMP) accumulation occurs in nerves or smooth muscle of saphenous vein, infusions of 6-hydroxydopamine (6-OHDA) were administered to dogs with the aim of inducing sympathetic nerve damage. The effects of 6-OHDA on other 5-HT1-like receptor-mediated responses at the pre- and post-junctional level were investigated for comparison by studying 5-hydroxytryptamine (5-HT)-induced inhibition of 3H-noradrenaline release and contraction of smooth muscle respectively. Disruption of nerve function by 6-OHDA was revealed by the lack of catecholaminergic fluorescence and neurogenic contractile responses in saphenous veins from dogs treated with 6-OHDA. In addition, severe impairment of neuronal uptake mechanisms were apparent since basal efflux of 3H-noradrenaline, electrically-evoked release of 3H-noradrenaline and remaining 3H-noradrenaline content were considerably reduced. Some 3H-noradrenaline was taken up and released in 6-OHDA-treated tissues which is consistent with the existence of nerve varicosities resistant to the present dosing regime of 6-OHDA, an observation substantiated by electron microscopy studies showing inconsistent lesions of nerve terminals. 6-OHDA pre-treatment potentiated the smooth muscle contractile responses mediated by 5-HT1-like receptors as well as potentiating 5-HT-evoked inhibition of prostaglandin E2-stimulated cyclic AMP accumulation. It did not, however, affect 5-HT-induced inhibition of 3H-noradrenaline release. The present results suggest that inhibition of cyclic AMP accumulation by 5-HT occurs predominantly in smooth muscle.

Animals↗
PubMed1991

Transient hyperphosphatasaemia in association with acute infection in adults.

The causes of raised serum alkaline phosphatase were determined prospectively in a consecutive series of 2884 acute medical admissions. Diagnoses were established by pre-defined clinico-pathological criteria. Two hundred and four patients had hyperphosphatasaemia. Liver and bone disease accounted for only 98 (48%) of the established diagnoses. The diagnosis was not established in 31 (15%). Transient hyperphosphatasaemia occurred in 66 (32.4%) cases. In 25 of these patients (12% of the total) an acute infection was the sole illness identified. In this infected group, the isoenzyme type was predominantly hepatic, although jaundice occurred in only 3 patients. Discriminant analysis revealed that this group was characterized by haematological and biochemical features of an acute phase response. Transient hyperphosphatasaemia is commonly found in acutely ill medical inpatients and is frequently associated with acute extrahepatic infection.

Acute Disease↗