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Biomedical subjects

I D Johnston

Publications and source records attributed to I D Johnston.

At least 19 recordsLinked to original sources
PubMed1979

Severe hypertension in primary aldosteronism and good response to surgery.

11 patients with primary aldosteronism have been encountered over 11 years and submitted to surgery in a provincial teaching hospital serving a population of 3 million. Contrary to classical teaching, the hypertension has usually been very severe. Precise identification of the site of the lesion preoperatively has been possible by the measurement of adrenal-vein aldosterone levels, and results of surgery have been excellent. The iodocholesterol adrenal scan also correctly identified the site of the adenoma in 5 out of 7 patients in which it was used. Adrenal venography was of little value except in siting catheters.

Adenoma↗
PubMed1979

Total and free thyroid hormone concentrations after elective surgery.

Changes in thyroid hormone concentration and distribution and plasma cortisol levels have been followed in 11 patients undergoing elective cholocystectomy. A significant rise in total and free thyroxine (T4) and fall in total and free triiodothyronine (T3) were noted after surgery. Reverse T3 concentrations rose substantially, suggesting that peripheral conversion of T4 to T3 is diminished and that there is preferential formation of reverse T3. Serum thyroid stimulating hormone concentrations did not change. There was no direct correlation between the change in cortisol and the change in thyroid hormone or reverse T3 concentrations.

Adult↗
PubMed1979

Parenteral nutrition in the cancer patient.

The nutritional state of patients with malignant disease must be assessed at the beginning of treatment. Nutritional supplements, given either orally or intravenously, enable patients to tolerate larger doses of chemotherapy and radiotherapy and the clinical response may be enhanced by nutritional support. Crystalline L aminoacids and glucose are the main nutrients used intravenously and fat emulsions are required in prolonged parenteral nutrition. Hypophosphataemia related to glucose administration and infection related to access to the circulation are the main complications, both of which are preventable. Total parenteral nutrition alone will not improve the results of cancer treatment significantly but its careful use in association with surgery, radiation therapy and chemotherapy can be most valuable.

Amino Acids↗
PubMed1978

Training for surgery.

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Education, Medical, Graduate↗
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↗
PubMed1977

Intravenous glucose, aminoacids, and fat in the postoperative period. A controlled evaluation of each substrate.

The metabolic effects of hypocaloric (2-51 MJ), equicalorific quantities of intravenous glucose, crystalline aminoacids, and soyabean emulsion were comapred with those of fasting in 4 groups of male patients (closely matched for age, weight, and fat-free mass) on the day of vagotomy and pylorplasty and on the fast 3 postoperative day. Patients given glucose alone excreted less nitrogen than the fasting patients but nitrogen sparing was greatest in the group given aminoacids alone. There was no evidence of any nitrogen sparing when intravenous fat was the source of energy. There was no difference in blood glucose, free fatty acids, and insulin concentrations among the groups. Ketone-body concentrations rose in the fasting and fat-fed groups but remained low in the groups who received glucose or aminoacids. This study indicates that, in the short term, the increased preservation of protein achieved by the infusion of aminoacids compared with that produced by the traditional infusion of glucose does not warrant the extra cost involved.

Adult↗
PubMed1977

Carbohydrate tolerance with portal and systemic venous drainage of the pancreas.

Carbohydrate tolerance was studied in 8 dogs with pancreatic venous drainage to the hepatic portal vein and 6 dogs with pancreatic venous drainage to the systemic veins. While systemic venous drainage of the pancreas was associated with higher fasting plasma insulin and lower fasting plasma glucose levels, no significant differences in either glucose clearance or insulin response to glucose were detectable. Therefore, in the maintenance of plasma glucose homeostatis, administration of insulin into the portal vein offers no significant advantages over the easier systemic route.

Amylases↗
PubMed1977

Hypothyroidism following partial thyroidectomy for thyrotoxicosis and its relationship to thyroid remnant size.

One hundred and twenty-two patients were reviewed 1-7 years after partial thyroidectomy for thyrotoxicosis by two surgeons who had left thyroid remnants of different size. There was no significant difference in the prevalence of hypothyroidism or in the serum levels of thyroxine, tri-iodothyronine or thyroid-stimulating hormone between the two groups of patients. The overall prevalence of hypothyroidism was 16 per cent.

Adult↗
PubMed1977

Isolation of viable human pancreatic islets.

This article reports a method for the isolation of viable pancreatic islets from the human pancreas. Isolated islets were obtained from human pancreata of cadavers, patients undergoing surgical operations, and fetuses, using a freehand microdissection procedure. Viability was assessed by light microscopy of sections stained with aldehyde fuchsin and by measuring the insulin output of islets in response to a glucose stimulus in vitro using a perifusion system. Ten pieces of cadaver pancreas were studied. Islets were isolated from 6 specimens and in 5 of these were shown to respond to a glucose stimulus in vitro. Histologically the islets showed minimal damage with slight degranulation of the beta cells. Five pieces of pancreas removed at operation were studied as well. Islets were isolated in all cases, but only 2 showed a response to a glucose stimulus. Pancreata from a 26-week and 34-week human fetus were also studied. It was not possible to microdissect islets from either case, but small pieces of pancreas from the 26-week fetus were shown to respond to a glucose stimulus by producing a significant increase in insulin output.

Cadaver↗
PubMed1977

The effect of surgical operation on venous plasma free amino acids.

The effects of abdominal operation on the antecubital vein plasma amino acid concentration were examined. With four groups, each containing ten patients, factors such as severity of surgical operation, anesthesia, and postoperative nutrition were examined. Immediately after operation there is a fall in the plasma concentrations of most amino acids; the nonessential amino acids (glutamate, proline, glycine, alanine, histidine, and arginine) continue to fall during the 2 postoperative days, whereas the essential amino acids (isoleucine, leucine, phenylalanine, and lysine, with tyrosine) are at higher concentration at 48 hours than immediately after operation. Comparison of a group of patients undergoing an operation of moderate severity (vagotomy and pyloroplasty or cholecystectomy) with those having the more severe procedure of resection of aortic aneurysm with Dacron graft replacement suggests that these general changes in amino acid concentrations do not appear to be due to the severity of the operation, although cystine levels were lower, and phenylalanine levels were higher, in the graft-replacement group. The changes did not appear to be the result of anesthesia. Increasing the postoperative glucose intake was associated with higher plasma alanine and lower methionine levels. It is suggested that, in surgical patients, cystine and tyrosine may become essential amino acids and rises in phenylalanine and methionine indicate transient liver dysfunction. The data give support to the view that a high calorie intake after operation has a beneficial effect.

Abdomen↗
PubMed1976

Use of an elemental diet for long-term nutritional support in Crohn's disease.

An elemental diet was used for long-term (up to 360 days) nutritional support in eight patients with Crohn's diesease. They had lost 30% (range 18-37%) of their weight in health. A whole-body monitor was used to measure total body potassium as an index of the lean tissue mass. Three preoperative patients who has been unable to maintain their weight on a normal diet were able to restore 10% per month of their lost lean tissue once they were established on an elemental diet. In five patients who had had a successful resection of their bowel lesion the postoperative rate of restoration of the lean tissue mass while taking an elemental diet was 18.5% per month, while in two control postoperative patients on a normal diet it was 19% per month.

Adult↗