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Biomedical subjects

D Roberts

Publications and source records attributed to D Roberts.

At least 163 records · Page 9Linked to original sources
PubMed1996

Paracetamol self-poisoning. Characteristics, prevention and harm reduction.

BACKGROUND: Paracetamol is now the most common drug used for self-poisoning in the UK and is associated with potentially fatal liver damage. Patients admitted to hospital because of paracetamol overdoses were studied in order to determine their characteristics and factors which might have deterred them from taking paracetamol or reduced the dangers of the overdose. METHOD: Eighty patients were studied in hospital using a structured interview schedule, measures of depression and suicidal intent, information collected through the Oxford Monitoring System for Attempted Suicide, and the results of liver function tests. RESULTS: Acute liver dysfunction (25 patients) was associated with consumption of more than 25 tablets (odds ration 4.46, 95% CI 1.31 to 17.41, P = 0.014). The proportionate use of tablets from blister packs (60%) and loose preparations (46%; 5 patients using both types) reflected their general availability. More of those who took tablets from a loose preparation consumed 25 or more tablets (69%) than those who used a blister-pack preparation (40%; odds ratio = 3.0, 95% CI 1.12 to 9.95, P = 0.028). Only 20 patients thought that any type of warning label would have deterred them from taking a paracetamol overdose. CONCLUSIONS: Establishing a maximum number of tablets (e.g. 25) that can be available in individual preparations is likely to reduce the dangers of paracetamol self-poisoning. The potential effects of other measures are uncertain.

Acetaminophen↗
PubMed1996

The antidiabetic drug metformin elevates receptor tyrosine kinase activity and inositol 1,4,5-trisphosphate mass in Xenopus oocytes.

Although metformin is an important antidiabetic, its mechanism of action is still unknown. To study its mechanism, we examined metformin stimulation of insulin action on the Xenopus oocyte. Similar to therapeutic concentrations, maximal stimulation of insulin-induced meiotic cell division was achieved at about 1-10 microg/ml (or 7.7-77 /microM) metformin. An equivalent concentration of metformin was required to elevate receptor tyrosine kinase activity (in whole cells or a membrane-cortex preparation) and, through this tyrosine kinase activation, inositol 1,4,5-trisphosphate (IP3) production. With whole cells, the preincubation time for metformin stimulation of insulin action (approximately 1 h) was equivalent to the time required for metformin to maximize tyrosine phosphorylation and raise IP3, levels. With the membrane-cortex preparation, metformin was active within minutes; thus, metformin may act at an intracellular site. Since metformin can increase IP3, mass, we prevented elevation of calcium by prior microinjection of a calcium chelator or heparin (a drug that inhibits IP3 binding to the IP3 receptor). Both the chelator and heparin blocked metformin stimulation of insulin action on whole cells. Since microinjection of IP3, also stimulates insulin action, metformin may stimulate insulin action by elevation of intracellular calcium in addition to activation of the receptor tyrosine kinase.

Animals↗
PubMed1996

A leap in the dark.

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Financing, Construction↗
PubMed1996

Surgical treatment of coronary artery fistulae associated with other cardiovascular anomalies.

OBJECTIVE: To evaluate retrospectively our surgical experience, techniques and long-term results in 11 patients with coronary artery fistulae associated with other cardiovascular anomalies. METHODS: From January 1980 to April 1995, 11 patients with coronary artery fistulae associated with other cardiovascular anomalies were found among 20,000 open-heart procedures and treated surgically. Besides closure of the fistulae, coronary artery bypass grafting was performed in 5 patients with atherosclerotic coronary artery disease, and aneurysm angioplasty was done in 4 patients with coronary artery aneurysm. Ventricular septal defect and patent ductus arteriosus were closed in one patient and mitral valve replacement was performed in another patient. RESULTS: There were no surgical deaths, but one late death due to acute myocardial infarction occurred 6 months after surgery. The mean follow-up time was 75.7 months and all patients' functional status improved by an average 1.4 judged by the New York Heart Association functional classification. CONCLUSIONS: Coronary artery fistula associated with other cardiovascular anomalies will aggravate symptoms and cause deterioration of heart function. Therefore, evaluation and surgical intervention should be done as soon as possible to restore coronary blood flow and correct concomitant cardiovascular anomalies. The surgical results are excellent with a low operative risk and good long-term results.

Adult↗
PubMed1995

Shock-excited OH maser emission outlining the galactic center supernova remnant G359.1-0.05.

A search using the Very Large Array was performed for 1720-megahertz OH maser line emission from a number of nonthermal radio continuum sources in the galactic center region. The 1720-megahertz transition has recently been noted for its potential as a tracer of shock activity. The most striking result was the detection of extended 1720-megahertz OH maser emission, as well as a number of compact OH maser features, along the interface between a large-scale continuum shell (G359.1-0.5) and its surrounding ring of high-velocity molecular gas. The morphological correlation among the neutral gas, the nonthermal shell, and the maser features provides strong support for the hypothesis that the 1720-megahertz maser line of OH arises from gas shocked by the impact of the expanding supernova remnant into the molecular material. However, the radial velocities of the molecular cloud surrounding G359.1-0.5 are more negative than that of the OH maser spots by more than 50 kilometers per second. Here it is suggested that only the low-radial-velocity component of the carbon monoxide material at the limb of the remnant satisfies the physical conditions required for collisional pumping of the OH 1720-megahertz line behind the expanding shock front.

Astronomical Phenomena↗
PubMed1995

Search for B-->

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Journal Article↗
PubMed1995

Results of the international study of the implantable pacemaker cardioverter-defibrillator. A comparison of epicardial and endocardial lead systems. The Pacemaker-Cardioverter-Defibrillator Investigators.

BACKGROUND: The purpose of the present report was to document clinical experience derived from the implantation of 2834 epicardial and endocardial cardioverter-defibrillators (ICDs) in 2807 patients who were followed for almost 1 year and to compare the results obtained with the two systems. METHODS AND RESULTS: Patients in the two groups had similar clinical characteristics. More than half of the patients had a total of almost 50,000 spontaneous ventricular tachyarrhythmias that were terminated with equal success (approximately 98%) by epicardial and endocardial ICDs. Lead dislodgement and pocket infection occurred more often with the endocardial than with the epicardial ICD, whereas perioperative mortality was higher with the epicardial ICD than with the endocardial ICD. Mortality from sudden cardiac death was 1.4% in the epicardial ICD group and 0.6% in the endocardial ICD group at 1 year (P = .069). Overall mortality at 1 year was 12.2% and 6.9% for the epicardial and endocardial groups, respectively (P < .001), reflecting the higher surgical mortality for the epicardial system. CONCLUSIONS: The endocardial ICD is as effective as the epicardial ICD but incurs lower perioperative mortality.

Adult↗
PubMed1995

Half-dose aprotinin preserves hemostatic function in patients undergoing bypass operations.

High-dose aprotinin reduces bleeding in cardiac operations but with potential side-effects and increased cost. It is therefore mandatory that the effectiveness of a low dose be investigated. Half of the Hammersmith regimen was studied in cardiac surgical patients to find out how it could reduce bleeding. Blood fibrinolysis parameters were studied in 40 elective patients undergoing coronary artery bypass grafting in a double-blind, placebo-controlled study design. The plasma activities of tissue plasminogen activator, plasminogen activator inhibitor, alpha 2-antiplasmin, plasminogen, fibrinogen, and D-dimer as well as platelet number, bleeding times, activated clotting time, and aprotinin plasma concentrations were assessed before, during, and after the operation. Fibrinolysis was inhibited by aprotinin as evidenced by decreased D-dimer (p = 0.0001) and tissue plasminogen activator (p = 0.0432) levels and increased plasminogen activator inhibitor (p = 0.0105) and alpha 2-antiplasmin (p = 0.0002) levels during the operation. A postoperative abnormal bleeding time occurred 38% more frequently in the placebo group (p < 0.05). Aprotinin plasma concentrations reached adequate levels to inhibit plasmin and plasma kallikrein. This study showed that half-dose aprotinin significantly inhibits fibrinolysis and prevents postoperative abnormal bleeding time in cardiac surgical patients.

Aged↗
PubMed1995

Application of a modified INCSTAR Epo-trac 125/RIA for measurement of serum erythropoietin concentration in elite athletes.

OBJECTIVES: To evaluate the analytical performance of a radioimmunoassay for measurement of erythropoietin. DESIGN AND METHODS: The INCSTAR Epo-trac 125I radioimmunoassay was examined for applications requiring sensitivity and precision within the normal range. RESULTS: Sensitivity was improved by increasing sample volume to 300 microL. Minimal detectable concentration was determined at 5.3 U/L, %CV ranged from 4.8-5.8 and 13.3-6.4 for intra- and inter-assay imprecision, respectively. Accuracy was maximized by controlling for lipemic and hemolyzed samples and ensuring serum was separated from the clot within 1 h of collection. Values demonstrated good correlation to the Diagnostic Systems Laboratory RIA-kit. CONCLUSIONS: With sample volume increased to 300 microL and control of sample preparation, the INCSTAR Epo-trac 125/RIA showed improved precision. Assay sensitivity at lower values allows resolution of changes in erythropoietin within the normal reference range. Age was not found to influence erythropoietin concentration. Within 10 days sojourn at moderate altitude an increase in circulating erythropoietin and reticulocytosis was observed in swimmers.

Adolescent↗
PubMed1995

Fetoplacental histology as a predictor of karyotype: a controlled study of spontaneous first trimester abortions.

It has been suggested that inferences about fetal karyotype can be made from examination of placental and decidual histology in early, spontaneous abortions (SABs). We assessed the reproducibility and predictive value of histologic features in 75 karyotyped, first trimester SABs; 32% (24 of 75) had normal male karyotypes (46,XY) and 68% (51 of 75) were cytogenetically abnormal (29 trisomy, 12 triploidy, eight monosomy X, and two tetraploidy). Three pathologists independently assessed 17 fetal, placental, and decidual histological findings and made predictions about the karyotype (normal, abnormal, or uncertain). Good to excellent interobserver and intraobserver reproducibility (kappa > 0.58) was achieved for the identification of five histological features: villous cavitation, anucleate fetal erythrocytes, amnion, umbilical cord, and fetal tissue. When histology and karyotype were compared using Fisher's exact test, no histological feature was associated with "any abnormal karyotype," two features (anucleate, fetal erythrocytes and umbilical cord) were associated with a normal karyotype, two features (villous dysmorphism and cisterns) were associated with triploidy, and four features (villous hydrops, no umbilical cord, no fetal tissue, and no anucleate erythrocytes) were associated with trisomy. Despite these significant histological-cytogenetic associations, the positive predictive values of each of these histological features with their corresponding karyotypes were low, ranging from 0.41 to 0.73 (mean, 0.53). Our data suggest that certain histological features in first trimester SABs are associated with the SAB's karyotype and are reproducible; however, such histological features did not perform as well as diagnostic tests for predicting the likelihood of normal versus abnormal karyotype.

Abortion, Spontaneous↗
PubMed1995

Effects of an antiperspirant with emollients on foot-sweat accumulation and blister formation while walking in the heat.

BACKGROUND: Friction blisters are a common injury in sports activities and military operations. Blisters can compromise performance, so it is important to devise preventive strategies to reduce these injuries. OBJECTIVE: This study investigated the influence of an antiperspirant with emollient additives on frequency and severity of friction blisters, hot spots, and irritant dermatitis. METHODS: Twenty-three healthy men walked on a treadmill (1.39 m/sec, 1% grade) in a warm environment (28 degrees C, 25% relative humidity) carrying a total mass of 21 +/- 1 kg. For 4 consecutive days before the walk, the subjects' feet were treated with either (1) an antiperspirant (20% aluminum zirconium tetrachlorohydrex glycine concentration plus water) with emollient additives, (2) emollient additives alone (placebo control), or (3) nothing (nontreated). In two separate trials (1 month apart) each participant received the antiperspirant treatment and both control treatments (emollient [placebo] and no treatment). RESULTS: No differences were seen among treatment conditions for sweat accumulation (p = 0.86), blister incidence (p = 0.36), hot spot incidence (p = 0.83), or blister severity (p = 0.31). Irritant dermatitis was not reported in any of the treatment conditions. CONCLUSION: The use of an antiperspirant with emollients reduces irritant dermatitis but does not reduce total foot-sweat accumulation, blister or hot spot incidence, or blister severity.

Adult↗