Circadian variation of the streptozotocin-diabetogenic effect in mice

Summary Streptozotocin was injected in normal mice every 4h, during the day. Greatest number of diabetic animals were obtained at 16.00 h (95%) and lowest at 08.00 h (50%). Magnitude of hyperglycemia also showed similar distribution. This effect might be considered when planning its use for both experimental and clinical purposes.This work was done with funds provided by Conicet, Secyt and Cediquifa.Thanks are due to Dr W. E. Dulin for kindly provision of SZ and Mrs E. E. Gagliardino for technical assistance.     

Time-dependence of estradiol effects on protein synthesis in the rat neurohypophysis.

The incorporation of 3H-leucine into neurohypophyseal proteins was measured in vitro, 24 h after the administration of a single dose of estradiol (0.3 mug) to castrated female rats. Estradiol treatment caused a significant increase of 3H-leucine incorporation into proteins of the posterior lobe. The effects of estradiol depended largely upon time injection. Rats injected at 06.00 h, i.e., at the end of the dark period exhibited a 74% increase in protein synthesis, whereas rat injected at 14.00 h, i.e., at the middle of the light period only showed a 30% of increase.     

Postischemic ATP levels predict hepatic function 24 hours following ischemia in the rat

Hepatic function was assessed by the aminopyrine breath test (ABT) in male Sprague Dawley rats 24 h after partial hepatic ischemia. ABT decreased progressively to 26.3 (p less than 0.05) and 19.7% of dose (p less than 0.05) after 90 and 120 min of ischemia, respectively. ABT at 24 h after injury was correlated to the concentration of ATP in the ischemic lobes 1 h after the onset of reperfusion (r2 = 0.971) but not to ALT activity in plasma at 1 h (r2 = 0.391). We conclude that postischemic ATP levels are a better index of subsequent hepatic function than ALT.     

Kinetics of division in PHA-stimulated pig lymphocytes

Our results indicate that pig lymphocytes in culture complete their 1st division at 24 h. At 36 h there are 9% of cells in 2nd division. 3rd mitosis appears at 48 h; and at 72 h there are cells engaged in the 4th division.     

Postischemic ATP levels predict hepatic function 24 hours following ischemia in the rat

Summary Hepatic function was assessed by the aminopyrine breath test (ABT) in male Sprague Dawley rats 24 h after partial hepatic ischemia. ABT decreased progressively to 26.3 (p<0.05) and 19.7% of dose (p<0.05) after 90 and 120 min of ischemia, respectively. ABT at 24 h after injury was correlated to the concentration of ATP in the ischemic lobes 1 h after the onset of reperfusion (r²=0.971) but not to ALT activity in plasma at 1 h (r²=0.391). We conclude that postischemic ATP levels are a better index of subsequent hepatic function than ALT.     

Effect of relative humidity on the free-living stages of Strongyloides papillosus (Rhabdiasoidea: Nematoda)

The eggs and larvae are affected by the changes in the humidity level around them. The eggs do not develop below 87% relative humidity at 30 degrees C and 25 degrees C. At sub-developmental rel. hum. they remain viable for 30 h at 81%, but at 73% rel. hum. level they do not survive beyond 18 h. Survival of larvae in 100% rel. hum. is longer at 30 degrees C than at 25 degrees C and 35 degrees C, and also they exhibit a poor resistance to desiccation.     

Effects of retinoic acid on embryonic development of mice in culture

The effects of all-trans-retinoic acid (RA) (tretinoin) on the craniofacial development of mouse embryos were examined using whole embryo culture. In day 8 embryos cultured for 48 h, embryonic growth was inhibited concentration-dependently by all-trans-RA treatment. Most of the treated embryos exhibited hypoplasia of the primary palatal processes and a reduction in the development of the first visceral arches. In day 10 embryos cultured for 48 h, although embryonic growth was not inhibited at any concentrations of all-trans-RA, median cleft lip (93%), hypoplasia of the primary palatal processes (37%) and limb reduction deformities (48%) occurred commonly. Furthermore, RA treatment greatly reduced the size of the secondary palatal processes. The incorporation of 3H-thymidine in the treated maxillary processes was decreased to 65% of the control value at 1.0 x 10(-7) M all-trans-RA. These findings indicate that all-trans-RA is teratogenic in mouse whole embryo culture.     

Changes in gastro-intestinal serotonin content associated with fasting and satiation

Summary Rats fasted for 24 h were fed for 3 h, after whith time food was removed. Food intake decreased serotonin levels in the stomach and duodenum by 30 and 40%, respectively. These changes persisted for about 3 h. Food intake did not change tryptophan content in the stomach, while, in the duodenum, tryptophan level rose by 100% at the end of the feeding period and remained elevated for about 9 h.     

Role of extracellular matrix molecules in the development of the sodium current in quail mesencephalic neural crest cells

The occurrence of the voltage-dependent sodium current has been studied in developing neurons from quail mesencephalic neural crest on different substrates, using the whole-cell patch clamp technique. Explants from 9–12 somite embryos were cultured on dishes coated with type I collagen, fibronectin, laminin or on plastic dishes in a chemically defined medium. After 18 h of culture the sodium current was observed in 70% of the neurons tested, and at 24 h some of these neurons were able to generate an action potential. After 18–25 h cells grown on fibronectinor collagen I-coated dishes showed a significantly higher occurrence of the sodium current (83% and 84% respectively) as compared to cells grown on uncoated plastic dishes (51%). Moreover, in the presence of fibronectin, the current density of the sodium current was more than doubled in comparison with cells grown on other substrates.     

Effects of retinoic acid on embryonic development of mice in culture

Summary The effects of all-trans-retinoic acid (RA) (tretinoin) on the craniofacial development of mouse embryos were examined using whole embryo culture. In day 8 embryos cultured for 48 h, embryonic growth was inhibited concentration-dependently by all-trans-RA treatment. Most of the treated embryos exhibited hypoplasia of the primary palatal processes and a reduction in the development of the first viscreral arches. In day 10 embryos cultured for 48 h, although embryonic growth was not inhibited at any concentrations of all-trans-RA, median cleft lip (93%), hypoplasia of the primary palatal processes (37%) and limb reduction deformities (48%) occurred commonly. Furthermore, RA treatment greatly reduced the size of the secondary palatal processes. The incorporation of³H-thymidine in the treated maxillary processes was decreased to 65% of the control value at 1.0×10^–7 M alltrans-RA. These findings indicate that all-trans-RA is teratogenic in mouse whole embryo culture.     

Liver regeneration: Cultural characteristics of remnant liver cells following a second partial hepatectomy

Summary When a 38% hepatic resection (rat) is followed in 24–72 h by a 30% hepatic resection (in the same animal), in vitro cell survival is observed in liver remnant tissue removed at any interval following the second resection.     

Effect of amniotic fluid and fetal bovine serum on the morphogenesis of mouse duodenal villi in organ culture

Summary When duodenal explants of 15-day mouse foetuses are cultured in Trowell T8 medium during 72 h, villi do not develop. If mouse amniotic fluid (25%) is added to the same medium, short villi appear after 12 h of culture and medium size villi are seen at 48 h. Bovine amniotic fluid and fetal bovine serum promote cell growth but morphogenesis of intestinal villi is far less stimulated.Supported by grand MA-6069 from the Medical Research Council of Canada.     

Kinetics of division in PHA-stimulated pig lymphocytes

Summary Our results indicate that pig lymphocytes in culture complete their 1st division at 24 h. At 36 h there are 9% of cells in 2nd division. 3rd mitosis appears at 48 h; and at 72 h there are cells engaged in the 4th division.This work was supported by grants from the International Atomic Energy Agency, the Organization of American States and the Consejo Nacional de Investigaciones Científicas y Técnicas.We wish to thank for the technical assistance of Mr J. Serraïno.     

Effect of relative humidity on the free-living stages ofStrongyloides papillosus (Rhabdiasoidea: Nematoda)

Summary The eggs and larvae are affected by the changes in the humidity level around them. The eggs do not develop below 87% relative humidity at 30 °C and 25 °C. At sub-developmental rel. hum. they remain viable for 30 h at 81%, but at 73% rel. hum. level they do not survive beyond 18 h. Survival of larvae in 100% rel. hum. is longer at 30 °C than at 25 °C and 35 °C, and also they exhibit a poor resistance to desiccation.Acknowledgment. The author is grateful to Dr. Devendra Prasad of Patna University for his supervision and constant help in the work. The assistance of State University Grants Commission through a research scholarship is gratefully acknowledged.     

Evaluation of participation of glucose in elevation of glycemia of scorpion (Heterometrus fulvipes) caused by the hyperglycemic principle of the scorpion and crab

Summary A single injection of the hyperglycemic principle obtained from scorpion cephalothoracic ganglionic mass causes an elevation of glycemia in the scorpionH. fulvipes in which little glucose is involved (10.8%). With the crustacean hyperglycemic principle, the elevation of glycemia is initially almost exclusively contributed by glucose (glucose is 92% of total carbohydrate at 2 h post injection); 6 h after treatment, non-glucose carbohydrates appear to participate in the elevation of glycemia.Acknowledgments. We wish to express our gratitude to CSIR, New Delhi for providing financial support to P.S.R., Reprint requests should be addressed to Prof. R. Ramamurthi.     

Solubilisation de la monoamineoxydase des mitochondries de foie de rat

Summary The monoamineoxidase of the mitochondria of rat liver may be dissolved up to 50% of the initial activity by treatment with a tensioactive agent followed by ultracentrifugation. The best experimental conditions are obtained with 0.2% of sodium laurylsulphate (pH 7) during 1 h at + 2°C.     

Hemolymph regulation to hyposaline and hypersaline conditions inGammarus oceanicus (Crustacea: Amphipoda)

Summary Specimens ofGammarus oceanicus were exposed to sea water at salinities of 3%. and 55%. for various periods of time up to 24 h.G. oceanicus can regulate in hyposaline sea water and reached a new steady state after 4 h exposure to 3%. sea water. Its ability to regulated in hypersaline conditions is limited and no animals survived longer than 6–8 h in 55%. sea water. These results are discussed with respect to salinity conditions in the intertidal zone.Acknowledgments. Financial assistance from the University of New Brunswick Research Fund to K.H. is gratefully acknowledged.     

Résistance de la souris et du souriceau à l'hypothermie prolongée à 20° C. Observations portant sur près de 500 animaux

Summary We have found that mice can be made to live for more than 20 h when they are kept in hypothermia at 20 or 23° C without using any pharmacodynamic agents (more than 40 % over the whole of our experiments); a small number of animals succeed in living from 48 to 50 h under such conditions; injections with serum containing glucose allow this limit to be easily surpassed, since a mouse thus lived for 70 h. We have noted no difference in the resistance to prolonged hypothermia between males and females, or between the young mice and the adult ones.     

The metabolic fate of [35S]-diallyl disulphide in mice

Summary Diallyl disulphide (DADS) is a major constituent of garlic oil. Uptake of [³⁵S]-labelled diallyl disulphide by mouse liver is highest at 90 min after treatment. 2h after treatment with [³⁵S]-DADS, 70% of the radioactivity is present in the liver cytosol of which 80% is metabolized to sulphate.