Conversion of glutamate into aspartate in guinea-pig cerebral-cortex slices

1. When guinea-pig cerebral-cortex slices were incubated with [U-(14)C]glutamate as substrate, the specific radioactivities of the citric acid-cycle intermediates were lower than that of the aspartate isolated from the same vessels. 2. Aspartate was significantly labelled when [5-(14)C]glutamate was used as substrate and the aspartate contained almost no label when [1-(14)C]glutamate was present as substrate. 3. When specifically labelled glutamate was used as substrate, the label was found in the isolated aspartate in the position that would be predicted by citric acid-cycle mechanisms. 4. The results are consistent with the theory of ;compartmentation' of amino acid metabolism.

Mitral valve replacement: long-term results, with particular reference to changes in pulmonary vascular resistance

The first 16 patients to have mitral valve replacement with the Starr-Edwards prosthesis at St. Bartholomew's Hospital, London, were reviewed from one to three years after operation. These patients had presented with serious mitral valve disease and there was a high incidence of severe dyspnoea and persistent congestive failure before operation. There were four operative deaths, and two survivors had poor results due to regurgitation alongside the prosthesis. The remaining 10 patients showed considerable improvement. Although no diuretics were given after operation there was little dyspnoea and congestive failure resolved. Anticoagulant therapy is given after operation, and there have been few embolic incidents. The pulmonary vascular resistance was raised to between 6 and 11 units before operation in six patients. There was no undue mortality in this group, and post-operative cardiac catheterization showed a considerable fall in resistance and an increase in cardiac output, suggesting resolution of the pulmonary vascular obstruction. Tricuspid incompetence in these patients disappeared post-operatively. We conclude that mitral valve replacement can restore a patient severely disabled by mitral valve disease to a nearly normal life. We do not regard pulmonary hypertension as a contraindication to operation.

Hypertrophic pulmonary osteoarthropathy in association with pulmonary metastases from extrathoracic tumours

Three cases of pulmonary osteoarthropathy secondary to pulmonary metastases from extrathoracic tumours are described. Analysis of the reported cases shows that most of them were secondary to osteosarcoma, nasopharyngeal tumour, fibrosarcoma, and uterine tumour. Fibrous tumours and tumours with a predominantly fibrous stroma tend to be associated with osteoarthropathy more than others. This suggests that the fibrous stroma may be a factor in the stimulation of the reflex mechanism responsible for osteoarthropathy.

Mechanism of conversion of aspartate into glutamate in cerebral-cortex slices

1. When slices of guinea-pig cerebral-cortex slices are incubated with [U-(14)C]-aspartate and non-radioactive glucose as substrates, the specific radioactivities of the citric acid-cycle intermediates are lower than that of the glutamate isolated from the same vessels. 2. Glutamate was significantly labelled when [1-(14)C]-aspartate and glucose were present in the incubation medium. These results would not be expected on the basis of simple conversion of aspartate into glutamate through the citric acid cycle, since the C-1 position of oxaloacetate is decarboxylated in the conversion of isocitrate into alpha-oxoglutarate. 3. It appears that aspartate is converted into glutamate by citric acid-cycle mechanisms; however, the carbon ;skeleton' is not immediately condensed with acetyl-CoA to form citrate but first follows the cycle in a reverse direction to fumarate or succinate and then proceeds in the forward direction. 4. The conversion of aspartate into glutamate appears to be compartmentalized.

Radiology in epidemiological studies and some therapeutic trials

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Some observations on the lower urinary tract in infants with spina bifida cystica

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Assessment of radiological changes in the hands and feet in rheumatoid arthritis. Their correlation with prognosis

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The cause and significance of some long line shadows in the chest radiograph

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The angiogram in chronic nonspecific respiratory insufficiency

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