The count of blood platelets and sex in humans

Summary It has been shown that there is a higher count of blood platelets and thrombopoietic activity of plasma in women than men.     

Experimental immunity against trypanosomiasis

Summary 9 groups of 6 female rats were used in an experiment using fraction 3 ofTrypanosoma rhodesiense. 500 g gave 100% immunoprotection and 1000 and 1500 g gave 66% immunoprotection when challenged with 5×10² T. brucei. 2 groups of 10 female rats were tested for a short period inoculation immune response. In this, 750 g of fraction 3 ofT. rhodesiense gave 70% immunoprotection when challenged withT. brucei.I thank the University of Zambia for support; Dr M. A. Q. Awan, Mazabuka, Zambia, forT. rhodesiense andT. brucei; Prof. J. W. Kibukamusoke, Dr O. Okong'o and Dr W. W. Anokbonggo for advice; Mr L. Nyaliti for technical help.     

Reciprocal changes in serum free thyroxine fraction and thyrotropin level after administration of thiocyanate to rats

Summary The administration of thiocyanate to rats caused a significant increase of serum free thyroxine fraction, which coincided with the significant decrease of TSH level. The other components (AFT₄, T₄, T₃) in serum at this time were decreased or unchanged. The finding suggests the role of free thyroxine fraction in feed-back regulation of TSH secretion.Acknowledgment. We thank Dr A. Parlow and the NIAMDD, Rat Pituitary Hormone Distribution Program, for material for rat TSH immunoassay; Dr J. Nauman (Inst. Postgrad. Med., Warsaw, Poland) for T₃ antibody, and to Ing. J. Sadlo, Mrs M. t'astná and Miss R Fajkoová for technical assistance.     

Action of glutamic acid and of some glutamate analogues on the molluscan central neurones

Summary The effects of L-glutamic acid and of some glutamate analogues have been studied on the central nervous system of the snailHeobania vermiculata, using conventional electrophysiological techniques. The glutamate H-response had the mean equilibrium value of-(57±4) mV and was associated with a Cl^– conductance change. The D-response to glutamate application showed an involvement of sodium ions. Aspartate was agonist of glutamate action and displayed similar equilibrium value of the H-response, whereas quisqualate H-response was non-invertible.The authors wish to express their thanks to Prof. A. Curatolo for his continual interest and advice, and to Dr J. Stinnakre for the criticism of the text.     

Migration of lymphoid cells to the bone marrow of rat following eradication of cells in DNA synthesis and in mitosis

Summary Eradication of replicating bone marrow cells of rat by means of combined administration of single doses of hydroxyurea and vinblastin is followed within 9–10 h by an inflow of lymphoid cells of extramedullary origin in the range of 13,200,000/femur. The rat bone marrow with a high content of lymphoid cells was previously shown to be concentrated in stem cells. The factor(s) which convey the information of decrease of replicating marrow cells to extramedullary sites is at present unknown.Acknowledgment. This study was supported by a grant from the Chief Scientist Office, Ministry of Health, Israel.Hydroxyurea for this investigation was given as a gift by the Squibb Institute of Medical Research, Princeton, N.J. USA, to which the authors are indebted.     

The timing of cyclophosphamide therapy in tumor-bearing rats affects the resistance to tumor challenge in survivors

Summary Cyclophosphamide given to rats 2 or 5 days after an injection of Yoshida ascites sarcoma cured approximately the same proportion of animals, but the resistance to a subsequent tumor challenge was found only in rats treated with the drug 5 days after tumor injection.     

The effect ofγ-irradiation on soil enzyme stability

Summary Arylsulphatase, -1,3 glucanase, phosphatase and urease responded differently to -irradiation (5–50 Mrad) in air-dried and moist soils. In all instances phosphatase was the most stable. The variability between enzymes may be due to inherent biochemical and stuctural characteristics or to their location within the soil microenvironment.Supported by a grant from the NERC.     

Age-dependent response of lactate dehydrogenase of pituitary of rat to testosterone

Summary The effects of time and various doses of testosterone on the responsiveness of lactate dehydrogenase of pituitary of 7-, 38- and 78-week-old rats were studied. The activity of the enzyme increases in 78-week-old rats. Castration decreases the enzyme activity at all ages. Maximum increase in the enzyme activity is seen with 50 and 100 g of testosterone 4 h after administration of hormone to castrated rats. No further time and dose-dependent effect is observed. The magnitude of increase for the enzyme is higher at the age of 38 weeks and decreases in 78-week-old rats.To whom all correspondence should be addressed. The authors are grateful to Professor M.S. Kanungo, Biochemistry Laboratory, Department of Zoology, Banaras Hindu University for the suggestions and encouragement. K.V.G. thanks the PL-480 for a research fellowship.     

Hypnotic effect of serotonin administered in the vago-aortic afferent pathway

A minute amount of serotonin injected in the nodose ganglion circulation area develops abrupt myosis and general electrocortical synchronization activity in "encéphale isolé" Cat preparation. This hypnogenic effect of serotonin can still be reproduced after transection of vago-aortic nerves caudally to the nodose ganglia. The same injections become ineffective after rostral transection of the same pathway. These results suggest that serotonin may trigger some signs of sleep through peripheric nervous elements in which are probably localized in the nodose ganglia.     

Conversion of mammalian cyclic GMP-dependent protein kinase into modulator-dependent protein kinase (type II) in vitro

The spontaneous conversion of mammalian cyclic GMP-dependent protein kinase (G-PK) into modulator-dependent protein kinase (type II) (M-PKII) in the absence of cGMP or histone was observed in vitro. The findings, together with similarity in substrate protein specificity, suggest that M-PKII is the catalytic subunit of mammalian G-PK.