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Biomedical subjects

J Cooper

Publications and source records attributed to J Cooper.

At least 343 records · Page 19Linked to original sources
PubMed1991

Ethnic differences in fasting plasma C-peptide and insulin in relation to glucose tolerance and blood pressure.

The frequency of non-insulin-dependent diabetes mellitus (NIDDM) and of high blood pressure (or hypertension) is higher in some ethnic groups than in others for reasons that remain unclear. To investigate the mechanisms leading to these ethnic differences, plasma C-peptide and insulin concentrations were measured after overnight fast and during an oral glucose tolerance test in subjects aged 45-74 years sampled from the practice lists of two north west London health centres. Ethnic group was defined by grandparental origin as Afro-Caribbean in 106, Gujerati Indian in 107, and white European in 101. The total age-adjusted prevalence of NIDDM was 29% in the Afro-Caribbean, 30% in the Gujerati, and 3% in the white groups, respectively. Fasting C-peptide and insulin concentrations increased from the subgroup with normal glucose tolerance, through impaired glucose tolerance, to new NIDDM, and were lower again in subjects with known NIDDM. The odds ratio for new NIDDM was 1.87 (95% confidence interval 1.26-2.77) per 1 SD increase in fasting C-peptide, which was the most powerful independent indicator of new NIDDM (p = 0.0005) and accounted for the effect of ethnic group. Fasting insulin had a similarly strong effect. There was no relation between any index of insulin secretion and blood pressure or hypertension. There were differences among the ethnic groups in the C-peptide response relative to the insulin response. These results suggest that factors determining insulin secretion and its hepatic clearance, possibly including dietary fat, are the main causes of ethnic variation in rates of new NIDDM.

Aged↗
PubMed1991

Antithrombin III and arterial disease.

Cross-sectional studies suggest that both low and high antithrombin III levels are associated with the risk of arterial disease, principally ischaemic heart disease (IHD). The prospective relation between antithrombin III and subsequent death from arterial disease has been investigated in 893 men in the Northwick Park Heart Study. Antithrombin III levels were directly correlated with high rather than low levels of factor VII activity and of plasma fibrinogen. There were more deaths from arterial disease in the low and high thirds of the antithrombin III distribution than in the middle third.

Adult↗
PubMed1991

A prospective study of intraoperative pulse oximetry failure.

Since pulse oximetry is now an ASA standard for intraoperative monitoring, we sought to determine the intraoperative failure rate for this device. We prospectively evaluated the intraoperative failure rate of our pulse oximeters at the four University of Washington Hospitals (University of Washington Medical Center, Veterans Affairs Medical Center [VAMC], Children's Hospital and Medical Center, and Harborview Medical Center [HMC]) recorded from April 1989 to August 1989. We defined failure as the inability to obtain any oximetry reading for a cumulative period of more than 30 minutes during any anesthetic procedure after all equipment malfunctions had been eliminated. Our puse oximeters failed in 124 of 11,046 cases studied; this is a failure rate of 1.12%, which ranged from 0.56% at HMC to 4.24% at VAMC. The failure rate at VAMC (4.24%) was significantly higher than the other hospitals (p less than 0.001). Those cases associated with the pulse oximeter failure had the following characteristics: (1) an ASA status of 3 or higher, (2) lengthy operations, and (3) elderly patients. When the device did fail in a patient, it did not function for 32% of the mean anesthesia time. We conclude that the intraoperative use of the pulse oximetry can provide information about blood oxygen saturation in most patients. However, in approximately 1% of the patients we studied in the operating room, mechanically functioning pulse oximeters failed to provide readings of blood oxygen saturations during routine operative use.

Equipment Failure↗
PubMed1991

Elapsed treatment days--a critical item for radiotherapy quality control review in head and neck trials: RTOG report.

For all randomized trials since 1978, the Radiation Therapy Oncology Group has required the study chairman for radiation therapy to review the treatment given to each patient. The chairman scores the compliance of the treatment borders, total dose, fraction, and total elapsed time relative to the protocol prescription at the primary site, regional nodes, and any critical structure. The individual parameters are then considered together to derive an "overall" treatment score. For two RTOG head and neck studies in patients with moderately and very advanced carcinomas, the "overall" treatment was classified as unacceptable if the treatment at primary was scored unacceptable with respect to dose, fractionation, and field borders. However, prolonged elapsed treatment was not included. Analysis of these studies with 426 evaluable patients was performed to assess the relationship of unacceptable "overall" treatment compliance with outcome. Patients with prolonged treatment elapsed days (14 days beyond the protocol prescription) exhibited significantly poorer loco-regional control (13% vs. 27% at 3 years with p = .007) and absolute survival (13% vs. 26% at 3 years with p = .01). As a result, the criteria for unacceptable "overall" treatment were revised to include prolonged elapsed treatment days. Further multivariate analyses showed the revised criteria identified patients with significantly poorer loco-regional control and absolute survival even after adjusting for other prognostic factors.

Carcinoma, Squamous Cell↗
PubMed1991

A cross-sectional study of platelet cyclic AMP in healthy and hypertensive pregnant women.

1. Platelet activation in vivo occurs in healthy pregnant women and is more marked in women with preeclampsia. During pregnancy platelets have also been shown in vitro to be less susceptible to the inhibitory effects of prostacyclin. The cyclic nucleotide cyclic AMP has a key role as an inhibitory second messenger in platelets and mediates the inhibitory effects of prostacyclin. 2. We have studied cyclic AMP in relation to platelet behaviour in healthy pregnant women in the third trimester and in women with pregnancy-induced hypertension and pre-eclampsia. Non-pregnant young women were used as controls. 3. Pharmacological agents which increase levels of cyclic AMP were significantly less effective as inhibitors of platelet activation during pregnancy, but there was no difference between the healthy and hypertensive pregnant subjects. 4. Basal platelet cyclic AMP levels were the same in all three groups. However, the production of cyclic AMP in response to a range of adenylate cyclase stimulators was reduced during pregnancy, but again there was no difference between healthy and hypertensive pregnant subjects. 5. The reduction in platelet cyclic AMP levels in pregnancy occurred not only with those adenylate cyclase stimulators which operate via surface receptors, but also on direct stimulation of the enzyme with forskolin. 6. The most likely explanation of these observations is a reduction in the ability of the platelet adenylate cyclase enzyme to respond to stimulation of the third trimester of pregnancy. The consequent reduction in formation of the inhibitory second messenger cyclic AMP may in part be responsible for platelet activation in vivo during pregnancy. There does not appear to be a further difference in platelet cyclic AMP production in hypertensive pregnant women.

Adenylyl Cyclases↗
PubMed1991

Prognostic indicators for the development of AIDS in HIV antibody positive haemophiliac patients: results of a three-year longitudinal study.

In February 1986, 40 out of 75 adult patients with haemophilia A attending St. James's University Hospital were human immunodeficiency virus (HIV) antibody positive. Over a three-year period these patients were prospectively studied with regard to possible prognostic indicators for the development of the acquired immune deficiency syndrome (AIDS). Using the Centres for Disease Control (CDC) classification of HIV infection, 17 patients (42.5%) developed group 4 disease during this time, giving an actuarial three-year progression rate of 44%, and 5 patients (12.5%) died. The following parameters measured at recruitment were found independently to predict progression to AIDS: a serum beta 2-m level of greater than 3.5 mg/l, (chi 2 = 15.95, P less than 0.001), a serum IgA level of greater than 4.5 milligram(s) (chi 2 = 6.08, P less than 0.02) and p24 antigenaemia (chi 2 = 5.7, P less than 0.05). The actuarial three-year progression rate in those patients abnormal by two or more of these parameters was 100% (n = 7), compared to only 7% in patients who were normal by all three values (n = 15). CD4+ lymphocyte counts and CD4+:CD8+ ratios were significantly lower in HIV positive compared with HIV negative patients (P less than 0.01), but did not predict the development of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Normal length of fetal kidneys: sonographic study in 397 obstetric patients.

This study was done to measure normal lengths of fetal kidneys sonographically during pregnancy. Knowledge of these measurements may allow earlier diagnosis of a variety of abnormalities. The greatest length of each of 498 kidneys in 397 consecutive fetuses between 18 and 41 weeks gestation was measured on sonograms. Gestational ages were determined by last menstrual period and biometry; significant discrepancies led to case exclusion. Abnormal fetuses, twins, offspring of diabetic mothers, and fetuses with renal pelvic dilatation of 4 mm or greater were excluded to avoid any questionable measurements. The results show that mean lengths are greater and confidence intervals are wider than previously reported. Renal lengths are similar to those reported in premature and full-term neonates. Strong correlation exists between renal length and gestational age, determined by biparietal diameter, femoral length, and abdominal circumference, and an average of the three. No significant difference was found between right and left renal lengths in fetuses in whom both kidneys were imaged. Average renal lengths are significantly different when compared across the range of gestational ages (p less than .001). No correlation is seen (r = .00) between parental height or weight and fetal renal length. Our results show that fetal renal lengths are longer than previously reported.

Female↗
PubMed1991

Sedation for day-case urology: an assessment of patient recovery profiles after midazolam and flumazenil.

The specific antagonist flumazenil has been shown to reverse the central actions of benzodiazepines. Its use, in day-case procedures performed under benzodiazepine sedation, offers the potential for enhanced patient recovery. However, concern has been expressed over the possibility of resedation given the short elimination half-life of flumazenil. A randomised, double-blind, placebo controlled trial was therefore designed to assess patient recovery profiles after flumazenil. A total of 44 adults were entered into the trial. Recovery was assessed by means of a battery of psychomotor tests performed pre- and postoperatively. Psychomotor function in patients receiving flumazenil returned to, or near to, baseline levels within 15 min of administration--an improvement maintained throughout the 6 h test period. Patients receiving placebo did not recover fully until the 2 h test point--significant differences between the two groups existing at 15 min and 1 h. In this study, flumazenil effectively reversed midazolam-induced sedation without evidence of resedation. The implications for day-case surgery are discussed.

Adult↗
PubMed1991

The effect of potassium channel opening drugs on pulmonary nerves.

In the present study, the effects of cromakalim were studied in the in vitro innervated tracheal tube preparation. Cromakalim did not affect response of the trachea to exogenous acetylcholine but inhibited contractions of the tracheal preparation to stimulation of cholinergic pulmonary nerves via both transmural and preganglionic vagal stimulation. Glibenclamide significantly reduced the inhibitory effect of cromakalim on both preganglionic and field stimulated preparations. When tracheal tone was raised by a spasmogen, cromakalim had no effect on noradrenergic relaxations but facilitated nonadrenergic-noncholinergic relaxations to transmural stimulation.

Acetylcholine↗