Oscillations in the rate of disappearance of labeled triiodothyronine from human plasma and the minimum sampling rate for their observation

Conclusions Oscillations in the rate of disappearance of labeled-T3 have been observed in this experiment. A 4-h sampling period is insufficient to demonstrate this behavior; and sampling every 2 h appears to be an approximate upper limit on the sampling period. A more detailed knowledge of the character of these oscillations may be obtained by sampling more often than every 2 h during time intervals when the variations are largest. Curve A in Figure 2 suggests that sampling every hour during the mid-day would be desirable.The results about T3 reported here are not necessarily incompatible with reports that thyroxine (T4) concentration may not be diurnal, as discussed in the introduction. Although T3 and T4 are almost the same species, to within a single atom, their dynamics of distribution, binding and metabolism are sufficiently different 6 for one to be observedly diurnal and the other not. Another possibility is that diurnal variations may exist in T4 disappearance which arc too small to measure by currently available techniques.

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Résumé Des oscillations dans la réduction du taux de triiodothyronine (marquée¹²⁵I) ont été observées dans le plasma humain. On a trouvé qu'une période d'échantillonage de 4 h était insuffisante pour révéler ces oscillations. Une période de 2 h constituerait une limite supérieure adéquate.

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Reparto Medicina Nucleare, 11° Clinica Medica, Università di Roma (Italia).     

The effect of sleep deprivation upon variations in heart rate and respiration rate

Summary Variations in heart rate and respiration rate were found to be responsive to total sleep deprivation, particularly under experimental conditions more realistic to everyday life.     

Transmural pressure as a determinant of basic intrinsic heart rate

Summary It was observed the heart rate was minimum at zero transmural pressure. The mean heart rate at zero transmural pressure was 23±5/min. This mean heart rate increased from 23±5/min to a peak value of 40±6/min (74% acceleratin) when the transmural pressure was raised from 0 to +4 mm Hg and to a similar peak value of 36±8/min (56% acceleration) when the transmural pressure was lowered from 0 to –4 mm Hg. The peak values attained at ±4 mm Hg were higly significant (p<0.001). It is concluded that the heart rate at zero transmural pressure represents the basic intrinsic pacemaker frequency independent of neural, humoral, thermal and haemodynamically induced mechanical influences.     

The effect of some neurohormones on the heart rate of spiders

Résumé Les auteurs ont étudié l'effet de l'adrénaline et de l'acétylocholine sur le rythme du cur chez l'araignéeTegenaria atrica C. L. Koch. L'enregistrement s'est fait au moyen de l'électroencephalographe. L'injection de l'adrénaline provoquait l'accélération du rythme du cur, l'acétylocholine — son ralentissement.     

Changes in heart rate levels during avoidance conditioning in the rabbit

Summary During avoidance conditioning heart rate levels tend to increase or to decrease according to their initial values and these changes are not related to learning or performance of the task.     

Histone-induced macrophage disappearance reaction in normal guinea-pigs

Zusammenfassung Histon aus Kalbsthymus bewirkt nach i.p. oder s.c. Injektion bei nichtimmunisierten Meerschweinchen in gleicher Weise eine ausgeprägte Abnahme von Makrophagen in einem mit Glykogen induzierten Peritonealexsudat wie eine Injektion von Antigen bei spätallergischen Tieren. Eine Histonbehandlung während einer Immunisierung mit BCG unterdrückt die sonst mit Tuberkulin auslösbare sogenannte «macrophage disappearance reaction».     

Thrombin-induced ‘macrophage disappearance reaction’ in mice

Zusammenfassung Intraperitoneale Gabe von Thrombin verursachte ein praktisch völliges Verschwinden der Makrophagen aus der Peritonealflüssigkeit, beeinflusste aber kaum die Zahl der Lymphozyten.

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The authors thank Mr.A. Zsigmondy for his expert technical assistance.     

A sensorory input inhibiting heart rate in an insect,Rhodnius prolixus

The dorsal vessel of the blood feeding insect,Rhodnius prolixus, was found to increase or decrease its rate of contraction in response to a number of different stimuli. Handling increased contraction rates whereas tactile stimulation of the ventral abdominal cuticle inhibited contraction. Injection of very low concentrations of serotonin or of high concentrations of octopamine enhanced the inhibitory effect, apparently by acting via the nervous system. Higher concentrations of serotonin increased heart rate by acting directly on the myocardium. The inhibitory response is suggested to be one facet of a generalised thigmotactic response.     

Beta-adrenoceptor blocking drugs, heart rate and genetic hypertension development in rats.

In spontaneously hypertensive rats (SHRs) chronically treated during their growth with beta-adrenoceptor blocking drugs, no correlation was found between the reduction in heart rate and the prevention of genetic hypertension development.     

Effects of DL-propranolol on exercise heart rate and maximal rates of oxygen consumption inScaphiopus intermontanus

Summary Lymphatic injection of propranolol (0.2–10 g) into toads decreased exercise heart rate in a dose-dependent manner. There was a significant linear corrleation between exercise heart rate and maximal oxygen consumption rates . These data are consistent with the hypothesis that blood oxygen transport is the limiting process for max in anuran amphibians.This work was supported by a grant from the National Science Foundation (PCM-8021808). I am grateful to Dr P.C. Withers for logistical support and Dr S. Yokota for the initial idea.     

In vitro induced disappearance of nucleoli in cells treated with LSD-25

Zusammenfassung Nachweis, dass LSD Konzentration von 100 g/ml in der Gewebekultur zur Verminderung der optischen Dichte oder zum Verschwinden der Nucleoli führen kann.