A comparison between skin-photosensitizing (334 nm) activities of 8-methoxypsoralen and angelicin

Summary 8-Methoxypsoralen and angelicin, locally applied to the skin of the rabbit, photosensitized erythema under UV irradiation to an approximately equal extent. Incident UV irradiation was restricted mainly to 334 nm. This indicates that furocoumarin-DNA cross-links are not important in erythema induction.Acknowledgment. We are grateful to Professor G. Rodighiero for his kindness in supplying furocoumarins.     

Freeze tolerance in the frog,Rana sylvatica

Summary Wood frogs survive extracellular freezing at moderate subzero temperatures (–4°C) for at least 11 days. Freezing survival is aided by the accumulation of high concentrations of glucose as a cryoprotectant in blood and tissues. Glucose production was accompanied by a rapid decline in liver, but not muscle, glycogen levels suggesting that liver is the organ controlling cryoprotectant synthesis.Acknowledgments. This study was supported by grants to L.M.G. from the Kroc Foundation (Santa Ynez, California) and from the National Institute of Dental Research (Grant No. DE-03987). The authors wish to thank K. Yorko, M. Shakin, J. Finan and Mrs N. Manivannan for their technical and secretarial assistance.Acknowledgments. I thank Dr J. Ballantyne, Dr F. Schueler and I. McMurray for help with frog collections and Dr. W. Schmid, Dr J. Bogart and Dr F. Cook for helpful discussions. Supported by an N.S.E.R.C. operating grant and by a grant from the Atkinson Charitable Foundation.     

Evaluation of monoaminergic receptors in the genetically epilepsy prone rat

Summary The intensity of sound-induced convulsions in the genetically epilepsy-prone rat (GEPR) was reduced in a dose related fashion by intracerebroventricular administration of dobutamine, (₁ agonist), terbutaline (₂ agonist) or phenylephrine (₁ agonist). BHT-920 (₂ agonist) did not cause a dose-related decrease in sound-induced convulsion intensity. Binding studies showed that whole brain and receptor densities (B_max) were normal while the K_d was increased for the ligand in GEPR brain.Acknowledgment. We are most grateful to Boehringer Ingelheim for generously supplying BHT 920. We are also indebted to Ciba-Geigy Corporation for the gift of terbutaline hydrochloride and phentolamine hydrochloride. The work was supported in part by NIH grant NS 16829.     

Donor origin of the in vitro hematopoietic microenvironment after marrow transplantation in mice

Summary Bone marrow stroma from radiochimeric mice was established in culture. The polymorphic enzyme glucose phosphate isomerase (GPI) was used to determine the proportions of donor and recipient present in the original bone marrow and in cultured stroma. Bone marrow initially containing 95% donor GPI, when cultured and subsequently passaged for up to 8 weeks remained about 70% donor GPI. We conclude that many cultured stromal cells are donor derived in our radiochimeras and these are probably of hematopoietic origin.     

Identification of rooting depth and measurements of plant root activity in situ and in toto under field conditions using a gamma probe technique

Summary A technique for measuring root activity of agricultural crops in totality in situ under field conditions has been developed for the first time. The method essentially consists of measuring the activity emanating from roots after plant injection of a gamma radiating isotope using a probe. This also helps continuous monitoring of root growth changes over time.     

Cytosolic free Ca2+ in insulin secreting cells and its regulation by isolated organelles

Summary The role of Ca²⁺ in secretagogue-induced insulin release is documented not only by the measurements of⁴⁵Ca fluxes in pancreatic islets, but also, by direct monitoring of cytosolic free Ca²⁺, [Ca²⁺]_i. As demonstrated, using the fluorescent indicator quin 2, glyceraldehyde, carbamylcholine and alanine raise [Ca²⁺]_i in the insulin secreting cell line RINm5F, whereas glucose has a similar effect in pancreatic islet cells. The regulation of cellular Ca²⁺ homeostasis by organelles from a rat insulinoma, was investigated with a Ca²⁺ selective electrode. The results suggest that both the endoplasmic reticulum and the mitochondria participate in this regulation, albeit at different Ca²⁺ concentrations. By contrast, the secretory granules do not appear to be involved in the short-term regulation of [Ca²⁺]_i. Evidence is presented that inositol 1,4,5-trisphosphate, which is shown to mobilize Ca²⁺ from the endoplasmic reticulum, is acting as an intracellular mediator in the stimulation of insulin release.     

Partial purification and some characteristics of hamster molar alkaline phosphatase

Summary A rapid 3-step method is given to purify partially hamster molar alkaline phosphatase. Molecular weight was 50,200 and isoelectric point 3.7. The alkaline phosphatases in the mesenchymal and ectodermal parts of the tooth are probably identical.     

A quantitative morphological study of the optic nerve of pre-weanling rats

Summary A quantitative histological estimation of the optic nerve of pre-weanling rats has revealed that the total fiber number decreases rapidly between 7 and 25 days of age.Acknowledgment. We wish to thank Professor Clegg for advice and encouragement concerning this work.     

Systemic oxygen transport and erythropoiesis in the mouse

Summary Removal of 15% of blood volume in the mouse increases erythropoiesis by a factor of 2.2 when measured 12 h after bleeding. Exposure of normal mice to 40% reduced barometric pressure for the same period of time increases erythropoiesis only by a factor of 1.6. The response to hypoxia takes place in the presence of a 40% reduction of oxygen consumption and tissue-venous P_{o 2}, changes which are concomitant with a 5-fold increase in plasma erythropoietin activity. The larger response in anemic animals on the other hand occurs without any detectable change in these parameters. These results cast serious doubts about the interpretation of the quantitative homeostatic control of erythropoiesis based solely on the action of erythropoietin.Acknowledgments. This work was supported by a grant from the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina. We thank Isabel Zingariello for excellent technical assistance.     

Composition and novel pattern of emission of defensive scent oils in the larva of the contton seed bugOxycarenus hyalinipennis (Costa) (Heteroptera: Lygaeidae)

Summary differences in composition and pattern of eiission in the scent oils from the two abdominal scent glands in the larva ofOxycarenus hyalinipennis are reported. The scent oils contain hex-2-enal, oct-2-enal, dec-2-enal and 4-oxo-oct-2-enal.We thank D. E. Games for access to mass spectral facilities, M. Rossiter for recording the mass spectra, the Bayero University Higher Degrees Committee for providing funds to T. O. Olagbemiro and PPF International for supply of sample materials.