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Biomedical subjects

M J Knight

Publications and source records attributed to M J Knight.

34 records · Page 2Linked to original sources
PubMed1981

Exercise testing in children before and after surgical treatment of aortic stenosis.

Twenty-three children with valvar or discrete subvalvar aortic stenosis underwent a controlled, progressive bicycle exercise test within 6 months before and 3-30 months after surgery for left ventricular outflow tract obstruction. The patients were divided into three groups according to the preoperative resting gradient of left ventricular to aortic peak systolic pressure: 30-69 mm Hg (group A), 70-99 mm Hg (group B), and greater than or equal to 100 mm Hg (group C). Preoperatively, 19 of 23 patients (83%) developed significant ST depression (greater than or equal to 1.0 mm) during exercise, whereas only seven (30%) had abnormal ST depression at rest. Postoperatively, mean exercise-induced ST depression regressed to less than 1 mm in all three groups. In the total population the frequency of ST depression greater than 1 mm was significantly reduced after surgical treatment and mean total work and peak exercise systolic blood pressure were significantly increased within 12 months after surgery. Total work increased significantly in group B within 12 months and in group C within 13-24 months after surgery, but remained unchanged on group A. Peak exercise heart rates were similar before and after surgery in each group. Peak exercise systolic pressures increased after surgery in all three groups, but the mean differences were statistically significant only in group C patients tested 13-24 months after surgery. The results of this study show that exercise testing is useful for quantifying the severity of aortic stenosis and documenting the clinical improvement (or lack thereof) after surgical treatment, and that properly supervised exercise testing can be performed at minimal risk to children with significant aortic stenosis.

Adolescent↗
PubMed1980

Responses of normal children and young adults to controlled bicycle exercise.

Exercise responses were obtained from 149 children and young adults (average age 14.5 years) and divided by sex and body surface area (BSA): children with BSA less than 1 m2; children with BSA 1--1.19 m2; males with BSA greater than or equal to 1.2 m2; and females with BSA greater than or equal to 1.2 m2. Total work, mean and maximal power outputs were more affected by body size (height) than age in children with BSA less than 1 m2 and in males and females with BSA greater than or equal to 1.2 m2. Mean systolic pressure increased up to 64% above the preexercise supine value at peak effort, with the level of mean maximal systolic pressure having a positive relationship with body size (height), power output and preexercise sitting systolic pressure in all subgroups except children with BSA 1--1.19 m2. Mean diastolic pressure increased up to 24% above the preexercise supine value at peak effort. ST-segment depression of 1--2 mm was recorded in 12.1% (18 of 149) of the population at peak exercise. These changes occurred in 8.9% of all males and in 16.9% of all females (p greater than 0.1). The data from this study reveal the importance of sex and body size in the clinical interpretation of exercise responses in growing subjects, provide a reference for objective evaluation of subjects with or without cardiac abnormalities and provide a guide for careful monitoring of subjects during an exercise study.

Adolescent↗
PubMed1975

The aetiology of hypocalcaemia in acute pancreatitis.

Plasma calcitonin, glucagon and parathyroid hormone were measured in patients with acute pancreatitis. Plasma calcitonin was not detectable in 6 specimens obtained from the hypocalcaemic patients. Plasma glucagon values were similar in patients with acute pancreatitis and control subjects and were unrelated to hypocalcaemia, which was not even induced by glucagon infusion. High or rising parathyroid hormone levels were noted in association with hypo-and normocalcaemia, suggesting that parathyroid hormone rises and maintains plasma calcium within normal limits. Plasma parathyroid hormone was, however, undetectable in 8 patients with prolonged hypocalcaemia. Deficiency of parathyroid hormone due to its destruction by proteolytic enzymes or because of parathyroid gland exhaustion is suggested as the major factor inducing persistent hypocalcaemia in acute pancreatitis. Administration of parathyroid hormone should, therefore, be considered in patients with acute pancreatitis when hypocalcaemia does not respond to intravenous calcium therapy.

Acute Disease↗
PubMed1971

Possible use of glucagon in the treatment of pancreatitis.

Four patients with pancreatic disease received glucagon intravenously. In two a definite decrease in the volume of pancreatic exocrine secretion was shown, and in one of these pancreatic juice protein and bicarbonate levels also fell. Two patients with acute pancreatitis had pronounced relief of epigastric pain associated with falls in plasma amylase after intravenous glucagon.Several mechanisms could account for the possible beneficial effect of glucagon in pancreatitis, and further studies of its use in this disease are justified.

Abdomen↗