Development of plasma cortisol in calves from birth to 14 days of age]

Plasma cortisol was recorded in 15 calves from birth to 14 days of age by a radio-immunoassay technique. At birth mean cortisol value is 67.3 ng/ml; 6 hrs. later it decreases by 58.4% then it gradually diminishes and about 14 days after, it reaches adult levels (5.1 ng/ml).     

Influence of age on the renal renin response to a high salt intake in the rat

Saline drinking combined with DOCA-treatment was found to decrease renal renin in weanlings at a higher rate than in adult rats, with a comparable saline consumption level. The decrease was not potentiated by uninephrectomy.     

Influence of age on the renal renin response to a high salt intake in the rat

Summary Saline drinking combined with DOCA-treatment was found to decrease renal renin in weanlings at a higher rate than in adult rats, with a comparable saline consumption level. The decrease was not potentiated by uninephrectomy.     

The response of costal cartilage to changes in hormonal environment

Résumé 1^o L'hypophysectomie diminue l'incorporation de S³⁵ dans le cartilage costal de jeunes rats. L'hydrocortisone renforce l'action de l'hypophysectomie. Au contraire, le propionate de testostérone stimule la fixation de S³⁵ dans le cartilage costal. Un traitement à l'hormone de croissance donne und réponse qualitativement identique à celle obtenue avec le propionate de testostérone. 2^o Le propionate de testostérone, l'hydrocortisone et l'hormone de croissance n'influencent pas l'incorporation de radiosulfate chez le rat normal.     

Sexual differences in the development of plasma thyroxine levels in the embryo and young chick]

Plasma thyroxine (T4) levels were separately ascertained in male and female embryo and young chicken from the 12th day of incubation till the 4th day after hatching by the thyroxine binding globulin technique. In both sexes, plasma T4 reach a peak the 20th day of incubation, but values are significantly higher in females. A sharp decrease occurred thereafter, plasma T4 tending toward adult values the 4th day after hatching.     

Influence of the age of the mouse on the effectiveness of stimulation of its defenses by electromagnetic radiation]

Biological effects of microwaves on experimental trypanosomiase in the Mouse depends on the state of development of the animal. In fact such stimulation needs a mature immune system. Nevertheless, the increasing of the molecular immune response is only one of the aspects of protection mechanisms stimulated by such microwaves.     

Age-related adrenocortical response to short-term starvation in young rats

Summary In a study of the response to short-term starvation in 4-week-old and 7-week-old male rats, it was found that in the younger rats corticosterone levels rose earlier and reached higher levels; they fell after refeeding to a greater extent. Body weight loss followed the same pattern. Younger rats seem to adapt better to fasting and refeeding.     

Influence of previous temperature on stomatal response to osmotica

Zusammenfassung Die Spaltöffnungsweiten in der Epidermis von Blattscheiben ausNicotiana tabacum werden durch osmotisch wirksame Substanzen unterschiedlich beeinflusst, wenn die Pflanzen vorgängig bei verschiedenen Temperaturen aufwachsen. Bei 28°C sind die Spaltöffnungen der Blattstücke in osmotisch wirksamen Lösungen weniger geöffnet als in reinem Wasser, während sich bei einer Temperatur von 18°C die Spaltöffnungsweiten entgegengesetzt verhalten.

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Supported through the Center for the Biology of Natural Systems by National Institutes of Health Grant No. 5 P10 ES00139 and by Health Science Advancement Award No. 5 S04 FR06115 to Washington University from the National Institutes of Health.

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The technical assistance ofKathleen Dutson is gratefully acknowledged.     

Effects of testosterone propionate on LH and testosterone concentrations before and after the injection of gonadoliberin in young bulls pre-treated with dexamethasone]

This preliminary study has been performed on four young twin bulls, one pair aged 6 months and the other one aged 12 months. Plasma LH and testosterone were assayed from frequent blood sampling. Testosterone propionate (TP) following dexamethasone treatment did not significantly influence the LH response to gonadoliberin compared to the twin controls, although testosterone concentrations were high in those TP treated animals.     

Biosynthesis of macromolecules of the intercellular matrix in aorta organ culture. Influence of the age of the animal]

Rabbit aorta organ cultures were used as a model for the study of the modifications of the rate of biosynthesis of intercellular matrix macromolecules with age. Aortas of new born (100 g), young (400 g) and adult (2 kg) rabbits were maintained in culture for several weeks. 14C-lysine is incorporated in all the macromolecular fractions of the aortas, even in polymeric elastin. The change with age of the distribution of proteins of the aorta-explants in successive extracts obtained by a "chemical dissection" procedure and the decrease of their specific radioactivity wtih age enabled us to characterise biochemically the "aging program" of the arterial wall.     

Influence of age on calcification in homologous transplants in rats

Résumé Chez le rat, des homogreffes de peau ou d'aorte implantées dans le tissu souscutané ne se calcifient que si les receveurs sont jeunes (28 jours), quel que soit l'âge du donneur. Les dépôts calcaires sont localisés dans l'épithélium et les follicules pileux de la peau ainsi que dans les lamelles élastiques de l'aorte.     

Changes in the T4/T3 molar ratio following thyrotropin releasing hormone injection in cattle.

The injection of thyrotropin releasing hormone into cattle resulted in a rapid decrease in the T4/T3 molar ratio. 2 breeds of cattle, Shorthorn and Africander Cross were studied. The decrease in the T4/T3 molar ratio was significantly greater in the Shorthorn breed. It is concluded that acute stimulation of the thyroid gland with TRH results in enhanced release of both T3 and T4 and that T3 is discharged more rapidly than T4.     

Response to an antiestrogen as a criterion for hormonal sensitivity of endometrial cancer]

A test is described for the evaluation of hormone sensitivity of endometrial cancer in vivo. The concentrations of progesterone and estradiol receptors, and the activities of ornithine-decarboxylase and 17 beta-hydroxysteroid oxido-reductase enzymes have been measured in the tumor, before and after administration of the anti-estrogen tamoxifen. The responses observed, in particular the increase of progesterone receptor, could allow a more rational approach to hormonal therapy of endometrial cancer.     

Effect of amygdaloid lesions on plasma corticosterone response of the albino rat to emotional stress

Zusammenfassung Im Vergleich zu Kontrolltieren mit zweiseitigen Rindenläsionen führt beidseitige Zerstörung des Nucleus centralis im Mandelkernkomplex der Ratte zu erhöhter Plasma-Corticosteron-Produktion nach kurzfristigem Stress durch entsprechende Immobilisierung.

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This study was made possible by a special research fellowship to one of us,E. W. Bovard, from the United States Public Health Service, sponsored by the National Institute of Mental Health. The writers would like to acknowledge with thanks the interest and friendly cooperation of Dr.H. Jasper, Dr.Hanna Pappius, Dr.Marion K. Birmingham, and the medical and technical staff of Montreal Neurological Institute in this work. This paper was originally presented at a meeting of the Montreal Physiological Society, March 8, 1961.