The limitation of mitral echocardiography in combined mitral lesions

In combined mitral stenosis and incompetence, the mitral echocardiogram is able to estimate the degree of mitral stenosis (i. e. mitral valve area) without being able to detect or quantify mitral incompetence. A diastolic closure rate of 20 mm/sec or less does not exclude significant mitral incompetence as claimed by others. Cardiac catheterization is still necessary in mitral stenosis, where concominant mitral incompetence is suspected clinically, to confirm its presence and quantify its degree.     

Clinico-radiological and functional aspects of respiratory syndromes caused by collagen diseases

The clinical and radiological features in 100 patients with collagen diseases (rheumatoid arthritis, lupus, sclerodermia, dermatomyositis, and panarteritis nodosa) were compared with respiratory performance. 56 patients were drawn from the series of Pende et Al. and 44 from a personal series. The results are set out in tables and graphs. It was found that lung lesions due to collagen disease have no special clinical and radiological features. Respiratory performance is that of a restrictive syndrome that gradually progresses from A.R. to E.S., S. and P.M., accompanied by obstruction of the large airways, as shown by hyperinsufflation in sclerodermia and reduced specific conductance in rheumatoid arthritis.     

Recurrent hypernatremia; a proposed mechanism in a patient with absence of thirst and abnormal excretion of water

A 7-year-old girl twice developed severe hypernatremia (serum sodium values up to 194 mEq/l) without obvious cause. The ability of her kidneys to conserve water was normal, and increasing her plasma osmolality stimulated an appropriate ADH response. Unable to excrete a water load, her kidneys continued to conserve water even with a serum sodium concentration of 133 mEq/l. She was never thirsty and did not ingest sufficient fluid by choice. Although there was no demonstrable anatomic lesion, we postulate a localized defect of her thirst center. This may have modified release of ADH and resulted in an inability to dilute the urine by interrupting a pathway that could exist from the thirst center to the supraoptic nuclei. A therapeutic regimen based on these studies has prevented further hypernatremia.     

A method for stabilising technetium-99m exametazime prepared from a commercial kit

Technetium-99m exametazime (99mTc-d,l-HMPAO), prepared by the reconstitution of the Ceretec kit, is widely used in the investigation of regional cerebral blood flow. The radiochemical purity specification of not less than 80% lipophilic complex requires that the kit is used within 30 min of reconstitution. In certain circumstances this imposes restrictions on its clinical availability. A number of approaches to extending the 30-min shelf life have been proposed and these are discussed. A method of stabilising the kit by the addition of 200 micrograms cobalt chloride hexahydrate (CoCl2 x 6H2O) in 2 ml of water is described. The addition of this solution can extend the shelf life of the reconstituted kit to at least 5 h post reconstitution.     

Co-chairman's remarks: genetic recombination in the molecular era

The present status of some general questions about DNA recombination is assessed. Topics include the mechanisms of synapsis and strand exchange, and the functions of recombination in nature.