Release of prolactin and luteinizing hormone by histamine agonists in ovariectomized,steroid-treated rats under ether anesthesia

Responses to histamine agonists administered intraventricularly under ether anesthesia were analyzed to evaluate receptor mediation in histamine stimulation of prolactin and LH release in ovariectomized, estradiol-progesterone-treated rats (OVX-E2P-treated rats). Prolactin release was markedly increased by the H2-histamine agonists, 4-methyl histamine and Dimaprit. These effects were antagonized by metiamide, an H2-blocking agent. The H1-histamine agonist, 2-(2-pyridyl)ethylamine (PEA) in high doses released prolactin and its effect was partially prevented by metiamide. Mepyramine, and H1-antagonist, did not exert any effect on the release of prolactin enhanced by the histamine agonists. LH release was significantly increased after 4-methyl histamine administration. Its effect was weak and was blocked by metiamide. Neither Dimaprit nor PEA exhibited action on plasma LH levels. The results obtained with histamine agonists suggest that histamine evokes prolactin release in OVX,E2P-treated rats through H2-receptors. At present, conclusions on H2-receptor mediation in LH release induced by histamine cannot be drawn from these results. The above-mentioned data, however, conclusively discard a significant participation of H1-receptors.     

CO2 dissociation curves of oxygenated whole blood obtained at rest and in exercise

Summary In vitro CO₂ dissociation curves for oxygenated whole blood were determined in 19 healthy male subjects at rest and during submaximal and maximal bicycle work. Hemoglobin concentration and blood lactate increased with increasing work load and accordingly buffer value of the whole blood increased while bicarbonate and Base Excess (BE) decreased, resulting in a downward shift of the CO₂ dissociation curve during exercise. Despite the marked increase in buffer values of the blood, the slopes of the CO₂ dissociation curves during exercise were found to be about the same as those obtained at rest. It was inferred that the increasing effect of increased buffer value, on the dissociation slope, was essentially compensated by the decreasing effect of diminished bicarbonate content. The advantages of this relatively constant CO₂ dissociation slope for the indirect measurement of cardiac output by the Fick principle are discussed.     

Patterns of spontaneous unitary discharge in thalamic ventro-basal complex during wakefulness and sleep

Summary Influences of the wake-sleep states on spontaneous activity of thalamic ventro-basal neurons have been studied in the chronic cat using the following analyses for cell discharges: mean firing rate, interspike histogram and joint interval histogram (J.I.H.). While slow wave sleep is accompagnied by a characteristic firing pattern it is more difficult to compare spontaneous unit activity during wakefulness (W) and desynchronised sleep (D).A detailed analysis (especially of the J.I.H.) of the same neuron during the three states indicates marked differences between W and D; on the contrary, the intraburst pattern shows definite similarities between D and S. The greatest stability in the firing pattern of a given neuron is found during S on long recording. During D the variability in the firing pattern is mainly due to phasic activity but may also be related to tonic changes.     

Induktion von endogenem Pyrogen und Interferon durch Newcastle Disease-Virus in vivo

Zusammenfassung Die Ausbildung von endogenem Pyrogen und Interferon wurde nach der Injektion von NDV im Kaninchen untersucht. Das Auftreten und das Verschwinden beider Substanzen stimmte nicht nur zeitlich, sondern auch quantitativ überein. Zudem verliefen die Bildungskurven von endogenem Pyrogen und Interferon sowohl im Blut als auch in den Organen weitgehend gleichsinnig. Eine Abweichung von diesem Verhalten wurde lediglich in der Milz beobachtet, indem hier das endogene Pyrogen bereits nach 1 Stunde, das Interferon jedoch erst nach 3 Stunden den höchsten Gipfel erreichte. Dieser Befund deutet daraufhin, daß das endogene Pyrogen und das Interferon zwei verschiedene Substanzen sind.Die Exstirpation der Milz hatte ein gleichzeitiges Absinken des endogenen Pyrogens und des Interferons im Blut, jedoch nicht in der Leber, der Lunge und der Niere zur Folge. Hinsichtlich der Entstehung der partiellen bzw. kompletten Toleranz gegenüber dem NDV bzw. Influenza Virus A (PR8) dürften die beiden Substanzen demselben Mechanismus unterliegen.

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Induction of endogenous pyrogen and interferon by newcastle disease virus in vivo

Summary Endogenous pyrogen and interferon induced by injection of rabbits with NDV were investigated. The appearance and disappearance of both substances were in parallel in time as well as in quantity. The curves of endogenous pyrogen and interferon in the blood and in various organs tested usually were also parallel. Only in spleen highest titers of endogenous pyrogen were found already 1 hour after inoculation, whereas interferon activity reached its peak only after 3 hours. This finding indicated that endogenous pyrogen and interferon may be different substances.In splenectomized animals the blood levels of endogenous pyrogen and interferon were lower than those found in intact animals, while the titers in liver, lung and kidneys were identical. In respect to the formation of partial or complete tolerance to NDV and influenza virus A (PR8), respectively, both substances appear to be subjected to the same mechanism.

     

Receptive fields of single cells in the cat's superior colliculus

Summary Receptive field analysis of single units in the superior colliculus of the mid-pontine, pretrigeminal cat has confirmed previous reports of directionally selective units in the tectum. The directional property was based principally upon a unilateral inhibitory mechanism, although some directional responses to small moving objects depended equally upon summation of excitation. Receptive field size varied greatly, with field diameters not uncommonly exceeding 30 degrees. Fields near the area centralis and along the horizontal meridian tended to be smaller than those elsewhere. An inhibitory influence from the field periphery was demonstrated.Post-doctoral fellow of the National Science Foundation. Present address: Department of Experimental Psychology, Walter Reed Army Institute of Research, Washington, D. C. 20012 (USA).     

Chemotherapieinduzierte Veränderungen bei hochmalignen zentralen Osteosarkomen

High-grade central osteosarcomas are the most frequent malignant bone neoplasms in childhood and adolescence. Their prognosis has been substantially improved using neoadjuvant chemotherapy. The morphological examination of surgical specimens reveals important information regarding the success of treatment. The histological determined degree of regression represents one of the most reliable therapy-related prognostical factor. Thus pathological analysis of the surgical specimens is of great importance notwithstanding the improved clinical and radiological diagnostic of osteosarcoma.