PubMed Health⌕ Search

Biomedical subjects

A H McArdle

Publications and source records attributed to A H McArdle.

At least 19 recordsLinked to original sources
PubMed1994

Protection from radiation injury by elemental diet: does added glutamine change the effect?

The feeding of a protein hydrolysate based 'elemental' diet supplemented with added glutamine did not provide superior protection to the small intestine of dogs subjected to therapeutic pelvic irradiation. Comparison of diets with and without the added glutamine showed significant protection of the intestine from radiation injury. Both histological examination and electron microscopy showed lack of tissue injury with both diets. The activity of the free radical generating enzymes, scavengers, and antioxidants were similar in the intestinal mucosa of dogs fed either diet. After radiation, however, the activity of xanthine oxidase, superoxide dismutase, and glutathione peroxidase were significantly (p < 0.002) higher in the intestine of dogs fed elemental diet without the added glutamine. If the activities of these enzymes are important in the protection of the intestine from radiation injury, then the addition of extra glutamine may provide no benefit.

Animals↗
PubMed1992

Early enteral feeding, compared with parenteral, reduces postoperative septic complications. The results of a meta-analysis.

This two-part meta-analysis combined data from eight prospective randomized trials designed to compare the nutritional efficacy of early enteral (TEN) and parenteral (TPN) nutrition in high-risk surgical patients. The combined data gave sufficient patient numbers (TEN, n = 118; TPN, n = 112) to adequately address whether route of substrate delivery affected septic complication incidence. Phase I (dropouts excluded) meta-analysis confirmed data homogeneity across study sites, that TEN and TPN groups were comparable, and that significantly fewer TEN patients experienced septic complications (TEN, 18%; TPN, 35%; p = 0.01). Phase II meta-analysis, an intent-to-treat analysis (dropouts included), confirmed that fewer TEN patients developed septic complications. Further breakdown by patient type showed that all trauma and blunt trauma subgroups had the most significant reduction in septic complications when fed enterally. In conclusion, this meta-analysis attests to the feasibility of early postoperative TEN in high-risk surgical patients and that these patients have reduced septic morbidity rates compared with those administered TPN.

Adult↗
PubMed1991

Reducing parenteral energy and protein intake improves metabolic homeostasis after bone marrow transplantation.

The purpose of this prospective study was to compare the metabolic effects of reducing parenteral energy and protein intake in bone-marrow-transplant (BMT) patients from 150% (hi-TPN group) to 100% (lo-TPN group) basal energy expenditure. Cytotoxic therapy was given on days 1-5, BMT on day 6, and TPN beginning on days 6 or 7. The lo-TPN group exhibited higher serum albumin (38 +/- 0.4 vs 32 +/- 0.4 g/L, P less than 0.01) but similar nitrogen balance (-83 +/- 8 vs -86 +/- 8 mg.kg-1.d-1, P greater than 0.05). Serum Na+ remained greater than 134 +/- 1 mmol/L in the lo-TPN group but fell to 127 +/- 1 mmol/L in the hi-TPN group (P less than 0.001) despite similar Na+ intakes and balances. Serum K+ remained less than 4.4 +/- 0.2 mmol/L in the lo-TPN group but rose to 5.1 +/- 0.1 mmol/L in the hi-TPN group (P less than 0.01) despite similar K+ intakes and balances. Delivering TPN at lower-than-normal rates after BMT appears to minimize Na+ and K+ disturbances and improve serum albumin concentrations without having any adverse effect on nitrogen balance.

Analysis of Variance↗
PubMed1990

Marathon runners: the intestinal handicap.

Intestinal complications following strenuous, protracted physical activity have been increasingly recognized. Diarrhea, sometimes associated with blood loss, described in marathon runners does not appear to be a common diarrhea but rather the clinical expression of ischemic enteropathy. On the basis of experimental evidence and some clinical data, it is suggested that prefeeding an elemental semi-hydrolyzed diet might reduce the incidence and severity of this intestinal handicap in marathon runners. Perhaps, more importantly, the potentially adverse effects of acute ischemic enteropathy on the cardiovascular system might be accordingly reduced.

Cardiovascular System↗
PubMed1989

The effectiveness of protein supplementation on the nutritional management of patients on CAPD.

Repeated episodes of peritonitis cause malnutrition in CAPD patients because of increased protein loss into the dialysate, a high protein catabolic rate (PCR), and/or a decrease in appetite. The purpose of this study was to investigate whether protein supplements could improve the nutritional status of CAPD patients and secondarily reduce their incidence of peritonitis. Eight patients on CAPD were studied for 2 months as a baseline, then given protein supplementation for 4 months. There was significant (p less than .05) increase in dietary intake and nitrogen balance, with supplementation. The PCR decreased significantly (p less than .05). There was a concomitant decrease in the incidence of new episodes of peritonitis. In conclusion, protein supplementation can improve the catabolic state of CAPD patients.

Aged↗
PubMed1986

Prophylaxis against radiation injury. The use of elemental diet prior to and during radiotherapy for invasive bladder cancer and in early postoperative feeding following radical cystectomy and ileal conduit.

Previous studies done in animals have shown that significant prophylaxis against radiation injury could be afforded by feeding an elemental diet (ED) for three days before and during radiation. In the present study 20 patients were fed an ED for three days before and for the four days during radiotherapy (five fractions of 400 rad [4 Gy] each) prior to radical cystectomy and ileal conduit for invasive bladder cancer; ED feeding was recommenced 24 hours postoperatively via a feeding jejunostomy. The ED-fed patients exhibited positive nitrogen balance preoperatively and had an early return to positive nitrogen balance postoperatively (3.60 +/- 0.32 days). There was also prompt return of bowel sounds (3.00 +/- 0.32 days). Histologically and ultrastructurally, biopsy specimens of the ileal mucosa showed normal morphologic findings, with maintenance of normal levels of enzyme activity in the brush border. Severe or bloody diarrhea was absent in these patients. These data suggest that ED feeding provides prophylaxis against the acute phase of radiation injury in patients undergoing high-dose, short-course radiotherapy for invasive bladder cancer and that it is a safe and feasible means of postoperative nutritional support, even in the presence of a fresh bowel anastomosis.

Aged↗
PubMed1986

Effects of dietary intake on myocardial glycogen in rats.

Hearts with higher myocardial glycogen levels (MG) have improved tolerance to ischemia. The nutritional status of patients may influence MG levels and so its manipulation may be one way to delay myocardial damage during regional or global ischemia. In this study, the effects of a variety of dietary intakes were examined and correlated with MG levels in rats, grouped and fed in the following manner; Control; rat chow fed ad libitum, fasting of varying periods: 12 hr, 36 hr, 3 days, 5 days, and 7 days, diet manipulation; 4 groups pair-fed equicalorically with rat chow, chow and safflower oil, chow and safflower oil and dextrose, chow and dextrose. Daily weight change was recorded. At sacrifice, MG, myocardial DNA content, liver glycogen (LG), serum free fatty acid (FFA) were measured. It was found that fasting causes rapid elevation of MG within 12 hr, and during fasting the FFA level changes parallel with those of MG. Overall, weight gain had a positive correlation to LG and negative correlation to MG. With diet manipulation, certain substrates (dextrose), although equicaloric, resulted in greater weight gains and higher MG levels. Development of an optimum diet to augment MG and maintain good nutritional condition and to buy more time should be a useful clinical adjunct in patients suffering from unstable angina with high risk of imminent myocardial infarction and for preparing poor risk patients for cardiac surgery.

Animals↗
PubMed1985

Elemental diet as prophylaxis against radiation injury. Histological and ultrastructural studies.

We investigated whether elemental diet feeding would protect the intestine from radiation injury. Five dogs were fed an elemental diet for three days before receiving pelvic irradiation (500 rad/day for four days) and were maintained on the diet during the days of irradiation. These dogs were compared with five dogs that were fed normal kennel ration, but were treated similarly otherwise. One day and five days following completion of the radiation treatment, the dogs were anesthetized and a biopsy specimen of terminal ileum was taken for histologic and electron microscopic studies. In the dogs fed the elemental diet, there was no significant damage to the intestine seen on histological examination, and electron microscopy disclosed elongated microvilli and no organelle damage. However, both histological and electron microscopic examination of the intestine from dogs maintained on normal kennel ration showed that severe damage had occurred from the irradiation procedure. It seems, therefore, that the feeding of an elemental diet to dogs as a prophylaxis can afford protection to the intestine from the acute phase of radiation injury.

Animals↗
PubMed1984

Early enteral feeding of patients with major burns: prevention of catabolism.

The immediate onset of hypermetabolism after a major burn dictates that nitrogen and calories be supplied as early as possible to such patients to prevent the well-documented catabolic state. However, intravenous hyperalimentation is not always possible, and enteral feeding is not usually attempted in the early resuscitative period. Twelve patients with major burns (40% to 70%) were fed nasoduodenally in the early postburn period with a new solution (3.5% Aminosyn, 25% Polycose, and appropriate additions of electrolytes and vitamins). All patients reached positive nitrogen balance in 9.8 +/- 2.3 days, tolerated the feeding extremely well, and had no distention or diarrhea. Metabolic assessment showed remarkable stability. The characteristic signs of hypermetabolism, such as hyperglycemia and hypoinsulinemia or hyperinsulinemia, were absent. Furthermore, there was no persistent neutrophilia or leukocytosis and there was a significant (p less than .01) decrease in the percentage of juvenile neutrophils and a significant (p less than 0.001) increase in absolute lymphocytes between days 0 and 14 of the study. These data indicate that early enteral feeding of Polycose-Aminosyn is safe and well tolerated, and that the small intestine absorbs nutrients readily in the early postburn period, leading to positive nitrogen balance, preventing loss of serum protein, assisting in the maintenance of normal carbohydrate metabolism, and restoring granulocytes and lymphocytes to normal ratios.

Blood Cell Count↗
PubMed1982

Protection of ischemic myocardium: the roles of nutrition and myocardial glycogen.

The ischemic myocardium utilizes glycogen as metabolic substrate. The effects of oral nutrition on the levels of glycogen in the myocardium and of myocardial glycogen content on myocardial tolerance to ischemia were studied. Rats were divided into groups and fed (a) rat chow, (b) rat chow plus 5% dextrose, and elemental diets (c) Flexical (Mead Johnson) or (d) Vital (Ross Laboratories). Another group was starved. All fed groups gained weight normally while the starved rats lost 23% of their body weight. Compared with the effect on rat chow, myocardial glycogen levels were elevated in the Flexical and starvation groups, while Vital depressed the level (P less than 0.01). Thus, both caloric intake and diet affected myocardial glycogen content. Elevation of myocardial glycogen content after starvation contrasted with glycogen disappearance from the liver. The level of myocardial glycogen and left ventricular function after global ischemia were correlated in dogs under cardiopulmonary bypass conditions. During 30 minutes of normothermic aortic cross-clamping, hearts with a preischemic myocardial glycogen content greater than 0.4 g% had less asystole or ventricular fibrillation. Their left ventricular function (stroke work index, myocardial contractility) upon reperfusion was substantially better than those with a myocardial glycogen level of less than 0.4 g%. Dietary manipulation and the nutritional status can thus affect the myocardial glycogen content and may be useful in protecting the myocardium from ischemia.

Animals↗
PubMed1977

The enhancement of adenyl cyclase by steroid therapy in shock.

Hepatic and intestinal adenyl cyclase activity were measured after a single pulse injection of epinephrine or glucagon into normal dogs and into dogs subjected to hemorrhagic shock. The results indicated that hemorrhagic shock abolishes the increase in adenyl cyclase activity seen in normal animals following epinephrine and significantly reduces that induced by glucagon. These changes are reflected in the glucose production from the liver induced by these hormones. The response of adenyl cyclase to the in vitro addition of epinephrine or glucagon, as well as the nonspecific stimulator of adenyl cyclase, sodium fluoride, showed that it is the receptor site of the enzyme which is affected primarily by shock. The treatment of dogs with 30 mg/kg of methylprednisolone following the reinfusion of shed blood significantly improved the response of adneyl cyclase to epinephrine in both liver and intestine, and this improvement was reflected in the glucose production by the liver in response to the hormone.

Adenylyl Cyclases↗
PubMed1976

Transalveolar metabolic protection to the lung.

Radioactive glucose was administered as an aerosol to isolated rabbit lungs in an artificial thorax in order to investigate the capacity of the lung tissue to metabolize substrate supplied via the airway rather than via the circulation. Comparisons were made with radioactive glucose to which insulin had been added, with aerosolized distilled water, and with lungs that were neither ventilated nor perfused. The lung tissue utilized the aerosolized glucose as substrate (linear production of 14CO2 incorporation into lipid, and maintenance of high-energy phosphate content). Addition of insulin to the glucose did not alter the values. Ventilation with aerosolized water instead of glucose significantly reduced high-energy phosphate content, and these values decreased significantly further when the lungs were not ventilated. These studies confirm the fact that substrate can be utilized from the airway side of the lung, and encourage the speculation that it might prove therapeutically useful in pulmonary failure.

Adenosine Triphosphate↗
PubMed1975

Cyclic AMP response to epinephrine and shock.

Hormonal regulation is fundamental to homeostasis, and the response in tissues is mediated by adenosine 3':5' equals cyclic phosphate (cyclic AMP). Since circulating levels of catecholamines are elevated during hemorrhagic shock, experiments were carried out to study the effects of epinephrine and of shock on cyclic AMP levels of plasma and of the intestine, a particularly vulnerable organ in canine hemorrhagic shock. Epinephrine was given to normotensive dogs as a constant infusion (group 1) or as a single pulse (group 2). Sequential blood samples showed a marked increase in circulating cyclic AMP, especially in portal and hepatic venous blood. Little change was noted in the tissues. Hemorrhagic shock (group 3) induced a marked increase in plasma cyclic AMP, with a depletion of mucosal cyclic AMP and adenosine triphosphate (ATP). Pretreatment before shock with alpha-blockade (group 4) abolished the decrease in mucosal cyclic AMP and ATP, and reduced the increase in plasma cyclic AMP.

Acepromazine↗