High K+ content explains the abolition of the action potential in amphibian sciatic nerve in vitro byLathyrus sativus seed extract

Summary The action potential in amphibian sciatic nerve in vitro has been reported to be abolished by the topical application ofLathyrus sativus seed extract. We have confirmed this effect, but find that it is probably caused by the high K⁺ content of such seed extracts and that organic neurotoxins are not implicated.Acknowledgments. We thank the Wellcome Trust for financial support, Professor M.W. Bradbury for help with the ion determinations and Miss M.B. Burbridge of the Tropical Products Institute, London, for obtaining seed from Bombay, India.     

Influence of the thymus hormone on radioleucosis in mice]

A partially purified thymic extract has determined the development of leucosis in 10 thymectomized irradiated CC57Bl mice out of 25. The pure hormone isolated from the same extract prevented the development of leucosis in intact irradiated Mice. This seems to indicate the presence of a second active substance in the extract (enhancing the development of the leucosis).     

Human growth hormone in urine: development of an ultrasensitive radiometric assay

An immunoradiometric assay for human growth hormone (HGH) has been developed which has a detection limit of 1 ng/l and can measure HGH in unextracted urine from normal children and adults. The assay is based on a two-step procedure, using a solid-phase goat-anti-HGH immunosorbent for immunoextraction and [125I]-labeled monoclonal HGH-antibody for detection and quantification. The assay is not affected by urea, NaCl or changes of pH from 5-8. The mean urine HGH concentration in normal children is 6.78 +/- 7.6 (SD) pg/ml, in patients with HGH-deficiency 1.3 +/- 0.9 pg/ml which increases to 11.7 +/- 13.4 pg/ml on the day of growth hormone injection.     

Retroviruses released from a human tumor xenograft in nude mice induce colony-stimulating factor (CSF) activity in human fibroblastic cells

Summary A human colony-stimulating factor (CSF)-producing tumor transplanted into athymic nude mice released retroviruses in vitro. The viruses induced CSF activity in human fibroblastic cell lines.     

Homology of L-gulonolactone oxidase of species belonging to Mammalia,Aves, and Amphibia

Summary Immunological cross-reactivity of L-gulonolactone oxidase of different species (rat, chicken, and bullfrog) was tested by the Ouchterlony technique. Antiserum directed against the enzyme from chicken kidney reacted with rat liver enzyme as well as with bullfrog kidney enzyme. This finding suggests that there is, at least partly, sequence homology among the enzymes from species belonging to the three classes, Mammalia, Aves, and Amphibia.     

The activity of sorbitol dehydrogenase in some mammalian erythrocytes

Summary The activity of sorbitol dehydrogenase was found to be high in the red blood cells of man, dog, guinea-pig and mouse and comparatively lower in those of goat, sheep, rabbit, cat and rat.     

Renal effects of the inhibitor of thromboxane A2-synthetase OKY-046

Acute renal failure (ARF) was associated with increased urinary thromboxane (TXA2) excretion and lessened excretion of sodium (UNaV) and fractional excretion of sodium (FENa%). The inhibitor of thromboxane A2-synthetase OKY-046 enhanced sodium excretion and fractional excretion of sodium in normal and saline loaded animals whereas it partially prevented the reduction in sodium excretion and creatinine clearance and significantly increased fractional excretion of sodium in glycerol treated rats suggesting a partial protection against the development of acute renal failure.     

Survival of rabbit embryos after rapid freezing and thawing

Summary Frozen storage of rabbit embryos at the 16-cell stage in 2.0 M dimethylsulfoxide (DMSO) in phosphate-buffered saline (PBS) was achieved by a 2-step procedure. After storage for 10 days at–196°C they were revived by rapidly thawing at 500°C/min. On transfer of these embryos to pseudopregnant foster mothers, 50% survived to term. The difference in in vivo survival between frozen-thawed and frozen-thawed-cultured embryos was not significant.Acknowledgment. The authors thank the Director for the facilities. VHR is supported by Council of Scientific and Industrial Research (India).     

Penicillopepsin from Penicillium janthinellum crystal structure at 2.8 A and sequence homology with porcine pepsin.

The polypeptide chain of the acid protease penicillo pepsin folds via an 18-stranded mixed beta-sheet into two distinct lobes separated by a 30-A long groove which is the extended substrate binding site. The catalytic residues Asp-32 and Asp-215 are located in this groove and their carboxyl groups are in intimate contact. Alignment of the amino acid sequence with that of pepsin shows regions of high homology.