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Biomedical subjects

P D Wright

Publications and source records attributed to P D Wright.

At least 19 recordsLinked to original sources
PubMed1990

Laser recanalization versus endoscopic intubation in the palliation of malignant dysphagia.

Forty patients with widely disseminated or locally advanced malignant obstruction of the middle or lower third of the oesophagus underwent endoscopic treatment by either NdYAG laser recanalization or intubation. Groups were matched on the basis of tumour location and swallowing was graded clinically before and after treatment. Technical success was achieved in 17 of 20 laser treated and 18 of 20 intubated patients. Pretreatment swallowing ability, histology, tumour location and overall length were unrelated to functional outcome in both groups. However, circumferential tumour length identified endoscopically strongly influenced the quality of swallowing after laser recanalization. Patients with excellent swallowing quality (n = 7) had significantly shorter circumferential tumour lengths, 3.1(1.0) cm, than those with poorer quality swallowing (n = 10), 6.3(1.6)cm, (P less than 0.001). Both methods of treatment had low complication rates and there was one death in the series in the laser-treated group. Laser recanalization provides a better functional result than intubation for short (less than 4 cm) circumferential tumour. Intubation at a single session seems more appropriate than repeated laser therapy when tumour length exceeds 4 cm.

Aged↗
PubMed1989

In vitro study of human skeletal muscle strips: effect of nonesterified fatty acid supply on glucose storage.

To examine the effect of increased nonesterified fatty acid concentration on glucose storage in human muscle, an in vitro method for study of glycogen synthesis in this tissue has been established. Muscle strips obtained from rectus abdominus during elective abdominal surgery were clamped at resting length, and adenosine triphosphate/total adenosine nucleotide ratios remained constant for 3 hours ex vivo. Leakage of enzyme markers of muscle damage was minimal, and electron microscopy showed preserved myofibril ultrastructure. Insulin stimulation brought about a dose-dependent increase in rates of glycogen synthesis with a half-maximal effect at 9 x 10(-10) mol/L insulin. In 15 consecutive studies, basal rates of glycogen synthesis were 4.1 +/- 0.5, 3.2 +/- 0.7, and 3.0 +/- 0.3 nmol glucose/25 mg/h in the absence of palmitate, with 1.4 mmol/L and 2.8 mmol/L palmitate, respectively. Insulin-stimulated rates of glycogen synthesis were 8.6 +/- 1.2, 6.0 +/- 1.8, and 5.8 +/- 0.8 nmol glucose/25 mg/h. Thus, increasing fatty acid concentrations decreased rates of glycogen synthesis both basally and with insulin stimulation. The insulin signal itself was not affected as the percentage stimulation over basal rates remained approximately constant in the presence or absence of fatty acid (2.1-, 1.9- and 1.9-fold, respectively). Insulin sensitivity in vivo is usually expressed as absolute rates of glucose uptake during euglycemic hyperinsulinemia, and if plasma fatty acid elevation were to be studied in vivo an erroneous conclusion may be reached of resistance to hormone action per se.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Carnitine acyltransferases and acyl-CoA hydrolases in human and rat liver.

The activities of carnitine acyltransferases and acyl-CoA hydrolases were determined in human and rat liver to establish the validity of extrapolating from studies on rats to human metabolism. In human liver, carnitine acetyltransferase activity was 10-14 times higher and carnitine octanoyltransferase 1.7-2.4 times higher than in rat liver, while carnitine palmitoyltransferase activity was similar in human and rat. Acetyl-CoA hydrolase and octanoyl-CoA hydrolase activities were lower in human (42-57%) than in rat liver, but palmitoyl-CoA hydrolase activity was similar in both species. The activity of citrate synthase was lower (44%) in human than in rat liver. The low citrate synthase activity and the high carnitine acetyltransferase in human liver suggest that in man acetylcarnitine might be more important as a vehicle for export of acetyl units from mitochondria than citrate. The high activity of carnitine acetyltransferase in human liver is consistent with the observation that acetylcarnitine is the predominant acylcarnitine excreted in diabetic ketosis in man. It is concluded that the rat may not be a valid model for carnitine metabolism in man, and that in human liver carnitine may have an important role in transfer of acetyl groups out of mitochondria and possibly also to extra-hepatic tissues.

Acyltransferases↗
PubMed1987

Somatostatin, anaesthesia, and the carcinoid syndrome. Peri-operative administration of a somatostatin analogue to suppress carcinoid tumour activity.

A patient with carcinoid syndrome on long-term antiserotonin therapy with parachlorophenylalanine, experienced a flushing attack with hypotension during the prophylactic administration of aprotonin prior to the induction of anaesthesia. When she was subsequently prepared with a long-acting somatostatin analogue, octreotide (Sandostatin, Sandoz SMS 201-995), plasma levels of tumour-released hormones were reduced and anaesthesia for resection of hepatic metastases was uneventful. The advantages of an anaesthetic approach based on inhibition of carcinoid tumour activity, rather than antagonism of released hormones, are discussed.

Anesthesia, General↗
PubMed1986

Effect of branched chain amino acid infusions on body protein metabolism in cirrhosis of liver.

Thirty seven patients with established cirrhosis of the liver were subjected to measurement of body protein metabolism using L-(1-14C) labelled leucine as a tracer. The effects of disease severity and those of solutions containing 0%, 16%, 35%, 53%, and 100% branched chain amino acids were evaluated. Significant increases in protein synthesis were noted with solutions containing 35%, 53%, and 100% branched chain amino acids, but in patients receiving 100% branched chain amino acids without additional essential amino acid supplement the increase in synthesis was matched by a significant increase in protein breakdown. Protein balance was thus improved only in patients receiving 35% and 53% branched chain amino acids. It was concluded that the high increase in protein breakdown in patients receiving 100% branched chain amino acids was undesirable, and such a solution should not be recommended for clinical use.

Amino Acids, Branched-Chain↗
PubMed1986

Two-year experience of management of bleeding esophageal varices with a coordinated treatment program based on injection sclerotherapy.

The results of 61 consecutive patients treated for bleeding esophageal varices with a coordinated multidisciplinary protocol are described. The primary form of treatment after vigorous resuscitation was fiberoptic endoscopic injection sclerotherapy under general anesthetic. Thirteen patients failed to be controlled by injection, and eight were able to be treated by percutaneous transhepatic embolization. Those patients who were unable to undergo embolization or whose bleeding did not stop after embolization were controlled by surgery. The overall mortality rate with the 2-year limit was 29 patients (47%); however, only 18 deaths (29%) were related to the hospital admission for bleeding. Only one patient died of continued variceal bleeding. All of the other deaths were from later liver failure or unrelated disease. The results of the study confirmed the high mortality rate in patients with severe liver disease (Child's grade C) undergoing surgical control of bleeding, and it was shown that when control was obtained with injection sclerotherapy and embolization, the 1-year survival rate of a similar group of patients may be as high as 32%.

Anesthesia, General↗
PubMed1986

The management of severe brittle diabetes with "Infusaid" implantable pumps.

Two severely brittle diabetic patients were treated with "Infusaid" implantable insulin infusion pumps. Both were young females with recurrent ketoacidosis, prolonged or repeated hospital admissions, and subcutaneous insulin resistance. They also had psychological problems, and had seriously interfered with their treatment to induce glycaemic instability. Delivery of insulin from the pumps was intravenous (i.v.) in one patient, and intraperitoneal (i.p.) in the other. Following implantation, there was a marked improvement in glycosylated haemoglobin level (HbA1), fasting blood glucose (BG), daily insulin dose and hospitalizations. The beneficial effect has continued to date (9 months, and 12 months follow-up) with no major problems.

Adult↗
PubMed1985

The metabolism of 7-ethoxycoumarin in human liver microsomes and the effect of primary biliary cirrhosis: implications for studies of drug metabolism in liver disease.

Using 7-ethoxycoumarin as a probe substrate, microsomal monoxygenase activity has been measured in liver tissue from patients with primary biliary cirrhosis (PBC) of varying histological severity, and in histologically normal control tissue. Interindividual variation in enzyme activity was considerable, and in no histological category was the activity significantly different to control. We conclude that: (a) in PBC, hepatic microsomal monoxygenase activity is determined primarily by factors other than the histological severity of the liver disease, and (b) studies of xenobiotic metabolism in patients with liver disease should specify the nature of the underlying disease process.

Coumarins↗
PubMed1979

Glucose homoeostasis following injury.

Metabolic changes following injury have been observed for many years, and John Hunter discussed such changes in 1794. Changes in carbohydrate metabolism have been observed for a similar length of time, and glycosuria and hyperglycaemia have been reported by a number of observers. This paper records and quantitates the extent of hyperglycaemia in patients undergoing surgery of different degrees of severity and relates them to changes in blood insulin, growth hormone, cortisol, and catecholamine concentrations. Further animal studies were performed which suggested that a fall in intracellular glucose utilisation may be a contributory factor. The use of isotope labelling of glucose in man has enabled further studies to be done to clarify changes in exchangeable glucose mass, replacement rate, and space both in the normal situation and in the presence of infusions of glucagon, noradrenaline, glucose, and amino-acids. The hyperglycaemia is clearly the result of a complex interaction of changes in the availability and activity of hormones which control glucose metabolism both within and outside the cell.

Glucagon↗
PubMed1978

The plasma clearance of fructose and glucose during and after surgical operation.

Fasting blood glucose is elevated and the rate of disappearance of a glucose load is reduced after major surgery. Resistance to insulin is considered to play a part in post-traumatic glucose intolerance. Fructose metabolism is partly independent of insulin. Glucose and fructose clearance were compared in two groups of 6 matched male patients with normal glucose tolerance who were studied before and after major vascular surgical operations of the same severity. Fructose or glucose (25 g) was given intravenously over a 2-min period before, during and at intervals for 8 days after surgery. The rate of clearance of fructose increased significantly during operation (P less than 0.01), but returned to the preoperative level by the first postoperative day. Glucose clearance, in contrast, was reduced during and throughout the 8 days of the study. The fructose load produced a brisk insulin response before operation which was diminished and delayed during surgery. These findings suggest that administered fructose may be removed more rapidly than glucose during and immediately after surgical operation.

Aged↗
PubMed1975

The effect of surgical operation on growth hormone levels in plasma.

This study was designed to clarify the details of any changes in serum growth hormone levels occurring in surgical patients. Intravenous glucose tolerance tests were performed upon three groups of six patients each, Group I, minor surgery (inguinal herniorrhaphy), Group II, moderate surgery (vagotomy and pyloroplasty), and Group III, major surgery (aortofemoral bypass). Plasma glucose and serum growth hormone levels were measured. Depression of glucose utilization occurred together with elevations of fasting growth hormone levels and increased growth hormone responses to intravenous glucose. It is suggested that the increased serum growth hormone levels are a response to the glucose intolerance caused by operation, modifying the pituitary growth hormone release.

Adult↗
PubMed1975

Cellular glucose utilization during hemorrhagic shock in the pig.

To clarify the changes in glucose homeostasis which occur following injury, pigs were subjected to hemorrhagic shock. During shock increased levels of free glucose occurred in red blood cells and muscle tissue, suggesting that inhibition of glucose phosphorylation was occurring. Simultaneously systemic plasma glucose levels were noted to be higher than portal plasma glucose levels while levels of free glucose within the liver fell, indicating that the liver was mobilizing glucose. Plasma insulin and phosphate levels were observed to rise throughout the experiment. From this study it was concluded that the hyperglycemia of injury in these animals was caused by a combination of decreased cellular glucose utilization due to diminished phosphorylation and increased mobilization of glucose by the liver.

Animals↗