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Biomedical subjects

M Evans

Publications and source records attributed to M Evans.

At least 343 records · Page 19Linked to original sources
PubMed1985

Does mass closure of midline laparotomies stand the test of time? A random control clinical trial.

We compared the incidence of wound failure (burst abdomen and incisional herniation up to 4 years after operation) in a consecutive series of 282 major laparotomies closed with continuous monofilament nylon, and randomly allocated to mass (all layers except skin) or layered (anterior and posterior aponeuroses separately sutured) techniques. Surgeons were free to choose the site and direction of incision which resulted in a preponderance of midline incisions in the mass, and of paramedian incisions in the layered, group. One patient in the former, and two in the latter, burst their abdomens during early convalescence, and 17 incisional hernias were discovered within four years in the mass group compared with four in the layered group (log rank X2 7.16, P less than 0.01). Seven hernias in the former, and one in the latter, group were not detected within eight months of operation. We conclude that layered closure of a paramedian incision results in a lower incidence of incisional hernias than mass closure of a midline incision and that many hernias are not discovered until years after operation.

Abdomen↗
PubMed1985

Acid/alkaline ash diets: time for assessment and change.

The purpose of this article is to review critically the assumptions made to predict the effects of different diets on the pH of urine by calculations from food tables and lists of acid or alkaline ash in foods. Acid/alkaline ash calculations were completed for 7 days' worth of omnivore, lacto-ovo, and vegan diets. The vegetarian diets were significantly more alkaline than the omnivore diets, and the vegan diets were more alkaline than lacto-ovo vegetarian diets. The article discusses the history of the acid/alkaline ash concept, assumptions underlying it, mechanisms by which urine is acidified, how the acid/alkaline ash content of diets is calculated from food tables, difficulties arising in acid/ash calculations, and their validity in predicting urine pH. The authors conclude that while diet does influence the pH of urine, present calculation methods are time consuming, imprecise, and do not permit quantitative prediction of urine pH. Better methods for calculating the effects of diet on acid-base balance are needed.

Acid-Base Equilibrium↗
PubMed1984

Trials on trial. A review of trials of antibiotic prophylaxis.

The ability of a small-scale random-control clinical trial comprising less than 500 patients to disclose clinically important differences between treatment groups depends on the event rate in the control group. The high rate of wound infection after abdominal operations has attracted many trials of methods of antibiotic prophylaxis. We reviewed all of the pertinent English literature recorded in Index Medicus in 1980 and 1981. We examined 45 articles for defects in design, analysis, and presentation. Of the 45 articles, 25 reported statistically significant differences between treatment groups and 20, no significant differences. Unsatisfactory methods of randomization were used in four trials, ethics were questionable in 22, statistical methods were incorrect in 31, and presentation was inadequate in 40. We concluded that there is room for improvement in the conduct of clinical trials.

Anti-Bacterial Agents↗
PubMed1984

Sites of recurrent tumour after 'curative' colorectal surgery: implications for adjuvant therapy.

The pattern of recurrent tumour following 'curative' colorectal surgery was examined in a necropsy series and a prospective clinical series. In the necropsy series the commonest pattern of recurrence was disseminated disease (73 per cent) and recurrence in a single site was much less common (27 per cent). In the clinical series recurrence in a single site was commoner (55 per cent). The difference between the two series is statistically significant (P = 0.02, chi 2), and is probably due to under-diagnosis of disseminated recurrence in the clinical series. In both series local recurrence and hepatic metastases occurred almost equally but usually as part of disseminated disease. We conclude that after 'curative' surgery for colorectal cancer, recurrence is usually disseminated (73 per cent) and therefore therapy adjuvant to surgery should be active systemically. Adjuvant therapy directed at a single site (e.g. radiotherapy or intrahepatic chemotherapy) should be combined with a systemic therapy.

Adult↗
PubMed1984

Comparison of the prophylactic use of magnesium trisilicate mixture B.P.C., sodium citrate mixture or cimetidine in obstetrics.

The effects of magnesium trisilicate mixture B.P.C., sodium citrate mixture or cimetidine on gastric pH and aspirated gastric volumes were compared in 78 obstetric patients during elective (a), or emergency (b) surgery. Magnesium trisilicate mixture B.P.C. was associated with the most alkaline values of gastric pH (mean (a) 7.9, (b) 7.3; range 2.9-9.1). Sodium citrate 0.3 mol litre-1 mixture resulted in the narrowest range of pH values of gastric contents (mean (a) 5.4, (b) 5.9; range 3.9-7.7). The ranges of aspirated gastric volumes were wide with both antacid regimens (magnesium trisilicate 12-172 ml, sodium citrate 9-290 ml). Cimetidine increased gastric pH to greater than 2.5 in 82% of patients (mean (a) 6.2, (b) 5.0; range 1.6-7.3), and was associated with significantly smaller volumes of aspirated gastric contents (range 0.5-44 ml). When gastric pH and volume were considered together, the groups of patients who received cimetidine were found to be closest to the defined "safe limits", of pH greater than 2.5 and volume less than 25 ml.

Anesthesia, Obstetrical↗
PubMed1984

Blood pressure, electrocardiogram and echocardiogram measurements in the growing pony foal.

Twelve newborn pony foals underwent cardiovascular examinations (auscultation, arterial blood pressure measurements, electrocardiograms and M-mode echocardiograms) on their first day of life and then on Days 7, 14, 21, 30, 60 and 90. An age dependent, statistically significant, rapid increase of the arterial blood pressure in the first month was documented together with a slower decrease of the resting heart rate after two and three months of life. Innocent soft systolic murmurs were audible over the left heart base in a large number of the foals. The electrocardiograms showed age dependent increases of the PR-, QRS- and QT- intervals and a trend of the mean electrical axis in the frontal plane to rotate towards the left side. The ventricular dimensions, measured by M-mode echocardiography, increased with the growth of the pony foals. Linear regression equations were calculated for the right and left ventricular internal dimensions in relation to body weight (bwt). The other echocardiographic parameter had low correlations with bwt.

Animals↗
PubMed1984

Variations in circulating catecholamines fail to alter human platelet alpha-2-adrenergic receptor number or affinity for [3H]yohimbine or [3H]dihydroergocryptine.

A series of studies were performed to determine the relationship between physiologic levels of circulating plasma norepinephrine and epinephrine and human platelet alpha-2 binding site number and the affinity (KD) of these sites for antagonist radioligands. In one study, alpha-2-adrenergic binding site number and affinity were compared using both [3H]yohimbine and [3H]dihydroergocryptine as radioligands. There was good absolute and relative comparison for binding site number, but only a relative relationship for KD. In 46 normal subjects, there was no significant relationship between site number or KD and age, plasma epinephrine, or plasma norepinephrine concentration. Even after plasma epinephrine was raised nearly 20-fold by means of an intravenous infusion for 4 h in seven normal subjects, neither sites (608 +/- 68 vs. 567 +/- 120 sites/platelet) nor KD (2.01 +/- 0.94 vs. 2.14 +/- 1.15 nM) were significantly changed. Similarly, neither sites (445 +/- 55 vs. 421 +/- 53 sites/platelet) nor KD (1.44 +/- 0.29 vs. 2.10 +/- 0.75 nM) were significantly changed in six normal subjects when plasma norepinephrine levels increased during oral administration of prazosin for 1 wk. Thus, in a cross-sectional analysis and after a change in plasma catecholamine concentrations, there was no relationship in normal subjects between platelet alpha-2 binding site number or affinity of these sites for antagonist radioligands and the circulating catecholamine levels to which the platelets were exposed. In a group (n = 7) of patients who lack epinephrine-induced platelet aggregation due to abnormal thrombopoiesis, binding site number was decreased (304 +/- 36 vs. 572 +/- 29 sites/platelet, P less than 0.001) and KD tended to be greater (8.69 +/- 2.44 vs. 5.40 +/- 0.31 nM, P = NS) than in normal subjects (n = 46), despite having similar plasma catecholamine levels. There was no difference in binding site number (491 +/- 116 sites/platelet) and KD (5.61 +/- 0.84 nM) in patients (n = 5) with autonomic insufficiency and low levels of upright plasma norepinephrine when compared with the normal subjects. Two patients were examined before and after the removal of a pheochromocytoma. Their binding site number and KD were normal before the operation and essentially unchanged after the tumor removal and fall of plasma catecholamines. Thus, this study demonstrates that within the physiologic and pathophysiologic range of plasma catecholamines (in men), there is no relationship between the circulating catecholamine concentration and either platelet alpha-2 adrenergic binding site number or the affinity of these sites for antagonist radioligands.

Adult↗
PubMed1983

Two methods of skin closure in abdominal operations: a controlled clinical trial.

Operative bacterial contamination of surgical wounds is common. The ability of the host to eradicate these bacteria and prevent subsequent wound infection is affected by a number of factors; one of these has been shown experimentally to be the presence of suture material in the subcutaneous tissues. In a prospective randomized controlled clinical trial in 341 abdominal operations we compared the primary infection rates after two methods of skin closure: either vertical mattress monofilament nylon sutures (182 patients) or steel clips which penetrated only the dermis (159 patients). All patients received a single dose of a cephalosporin intravenously at induction of anaesthesia and neither sutures nor drains were placed in the subcutaneous plane. The overall wound infection rate in the sutured wounds was 17.0 per cent, compared with 6.3 per cent in those closed by clips (X2 = 9.26, P less than 0.01). We conclude that skin closure with clips reduces the incidence of wound infection in patients in whom operative parietal contamination has occurred.

Abdomen↗
PubMed1983

Does naloxone always act as an opiate antagonist?

Evidence for the ability of the opiate antagonist naloxone to block a variety of metabolic effects exerted by morphine and non-opiate drugs is reviewed. Naloxone prevents or reverses the following effects in the rat: (a) the chronic morphine-induced increase in liver [NADPH]; (b) the consequent chronic morphine-induced inhibition of liver tryptophan pyrrolase activity; (c) the resultant chronic morphine-induced enhancement of brain 5-hydroxytryptamine synthesis; (d) the similar effects on liver and brain tryptophan metabolism exerted chronically by other drugs of dependence (ethanol, nicotine and phenobarbitone); (e) the acute ethanol-induced increase in the hepatic [NADH]/[NAD] ratio. Naloxone also (f) inhibits basal and stimulated lipolysis in fed and 24hr-starved rats. This leads to prevention of (g) the consequent increase in the availability of circulating free tryptophan, and (h) the resultant tryptophan-mediated decrease in liver 5-aminolaevulinate synthase activity. The question of how many of these effects involve changes in endogenous opiates or at opiate receptors is not clearly understood at present and thus merits investigation. However, because most of the above effects are explained on biochemical grounds, and in view of evidence from behavioural and pharmacological studies [see (1)], the possibility must be considered that many of the actions of naloxone may be unrelated to its opiate-receptor-antagonistic properties.

Animals↗
PubMed1983

Role of tyrosine in the acute effects of ethanol on rat brain catecholamine synthesis.

Acute ethanol administration exerts multiple effects on rat brain catecholamine synthesis, associated with corresponding changes in cerebral tyrosine concentration. Catecholamine synthesis is enhanced at 1 hr by an increased availability of circulating tyrosine to the brain after inhibition of liver tyrosine aminotransferase activity. Tyrosine hydroxylation in vivo and tyrosine hydroxylase activity measured in vitro are also enhanced at 1 hr. Catecholamine synthesis is inhibited at 2-4 hr when tyrosine availability to the brain is decreased because of an enhancement of liver tyrosine aminotransferase activity. Serum neutral amino acid concentrations are decreased at 5 hr. This is followed 1 hr later by normalization of cerebral catecholamine synthesis. By 8 hr after ethanol administration, the latter becomes enhanced because of increased cerebral uptake of tyrosine. Catecholamine synthesis is inhibited at 12 hr because of enhanced transamination of brain tyrosine. Tyrosine metabolism finally returns to normal at 16 hr after ethanol administration. These results are discussed in relation to previous work with ethanol, and to central and peripheral mechanisms of regulation of brain catecholamine synthesis.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1983

Latamoxef for the prophylaxis of abdominal surgical wound infection: a controlled clinical trial.

In a series of 236 abdominal operations, patients were allocated at random to receive a single intravenous dose of either 1 g cephaloridine or 1 g latamoxef (at induction of anesthesia) for the prophylaxis of postoperative wound infection. Of the 116 patients given latamoxef, one developed major and seven minor wound infections, whereas five major and 21 minor infections occurred in the cephaloridine group (P less than 0.01). Latamoxef has now replaced cephaloridine as our prophylactic antibiotic of choice in potentially contaminated abdominal operations.

Abdomen↗