Oxytetracycline age validation of an adult shortfin mako shark Isurus oxyrinchus after 6 years at liberty.

This study presents findings on an oxytetracycline injected adult male shortfin mako Isurus oxyrinchus recaptured in waters off of southern California after 6 years at liberty. During the period at liberty, the vertebral band-pair deposition rate was validated at one per year. This result indicates that from a time at or near sexual maturity, male I. oxyrinchus in the north-east Pacific Ocean exhibit a band-pair deposition rate of one band pair per year, while deposition rates for juveniles in the area have been validated at two band pairs per year.

Stable isotopes and elasmobranchs: tissue types, methods, applications and assumptions.

Stable-isotope analysis (SIA) can act as a powerful ecological tracer with which to examine diet, trophic position and movement, as well as more complex questions pertaining to community dynamics and feeding strategies or behaviour among aquatic organisms. With major advances in the understanding of the methodological approaches and assumptions of SIA through dedicated experimental work in the broader literature coupled with the inherent difficulty of studying typically large, highly mobile marine predators, SIA is increasingly being used to investigate the ecology of elasmobranchs (sharks, skates and rays). Here, the current state of SIA in elasmobranchs is reviewed, focusing on available tissues for analysis, methodological issues relating to the effects of lipid extraction and urea, the experimental dynamics of isotopic incorporation, diet-tissue discrimination factors, estimating trophic position, diet and mixing models and individual specialization and niche-width analyses. These areas are discussed in terms of assumptions made when applying SIA to the study of elasmobranch ecology and the requirement that investigators standardize analytical approaches. Recommendations are made for future SIA experimental work that would improve understanding of stable-isotope dynamics and advance their application in the study of sharks, skates and rays.

Hemoperfusion for chronic schizophrenia: preliminary psychiatric results.

Six patients with chronic schizophrenia unresponsive to accepted therapy were assigned randomly to receive as adjunctive therapy either (A) weekly coated-charcoal hemoperfusion (CCHP) or (B) sham hemoperfusion (Sham HP) in a double-blind study using two independent psychiatric raters. Four weeks of treatment suggested that (1) CCHP was associated with significant improvement in some psychiatric measures, (2) improvement was early in the treatment course, and (3) neither CCHP nor Sham-HP was associated with deterioration in any of the psychiatric measures. When one patient from each group was "crossed-over" to receive the opposite treatment these conclusions were supported. Further studies appear to be warranted.

Further experience with peritoneo-venous shunt for ascites.

A specially devised pressure-sensitive valve forms the basis for a new peritoneo-venous shunt operation which delivers ascitic fluid continuously into the venous system. It is effective in ascites attributed to different causes. The procedure is simple and brings a long lasting relief with recovery in strength and nutrition and improved kidney function. Hepatorenal syndrome in ascites is reversed.

Renal effects of continuous negative pressure breathing.

Continuous negative pressure breathing (CNPB) was utilized to simulate the thoracic vascular distension of zero G or Space, in 11 anesthetized rats. The animals underwent renal clearance and micropuncture renal nephron studies before, during, and after CNPB. Four rats were pretreated with a high salt diet and I-M desoxycorticosterone (DOCA) in excess. None of these rats diuresed with CNPB. In contrast, five of the seven remaining rats increased the fraction of the filtered sodium excreted (CNa/GFR, p less than 0.05) and their urinary flow rate (V, p less than 0.05). Potassium excretion increased (UK V, p less than 0.05). End proximal tubular fluid specimen's TF/P inulin ratios were unchanged. Whole kidney and single nephron glomerular filtration rates fell 10%. CNPB, a mechanism for atrial distension, appears to cause in the rat a decrease in distal tubular sodium and water reabsorption. Exogenous mineral-corticoid prevents the diuresis, saluresis, and kaluresis. In a separate group of five rats, the CNPB was prolonged or excessive (CNPB greater than 3.5 cm H2O negative pressure); in these, the diuresis ceased and/or antidiuresis occurred. This confirmed the adequacy of other nonatrial volume control mechanisms in regulating renal salt and water conservation in opposition to the studied atrial-renal (Henry-Gauer) reflex of thoracic vascular distension. It encourages us to suggest that the atrial distension reflex diuresis that occurs with shifts of blood to the thorax in assuming a weightless condition, if comparable to the thoracic vascular distension of this model, will not progressively impair the circulation or the mammal but will be minor and short-lived.