Spatial interactions and stimulus-response relations of unit responses evoked by somato-sensory stimuli in the feline caudal medullary reticular formation.

Responses of neurons in the bulbar reticular area to separate and simultaneous stimulation of the forelimbs were recorded extracellularly in chloralose-anaesthetized cats. On increasing the stimulus intensity the number of spikes per response increased while the initial latency and interspike intervals decreased in accordance with the functional property of the neuron. Responses evoked by simultaneous stimulation displayed more spikes and a shorter latency than those evoked by separate stimuli of corresponding intensities. The differences in the responses evoked simultaneously and the sums of responses evoked separately showed characteristic distributions as a function of the latter. Three types of distribution were distinguished. The results indicate that stimulus-response relations play a determining role in the mechanism of spatial integration.

The role of "the law of initial value" and the levels of the central nervous system in the spatial interactions of blood pressure reflexes.

In experiments carried out on cats it has been found that various anaesthesia (chloralose, pentobarbital or urethan, given in doses of 50 mg/kg, 45 mg/kg and 800 mg/kg, respectively) did not influence the parameters of regression lines describing the spatial interactions of depressor reflexes of somatic and visceral origin. The individual differences showed a correlation with the "mean basal blood pressure" only. There was a linear relationship between the "mean basal blood pressure" and the X-axis intercepts of the regression lines. The size of the latters determined the extent of the facilitatory zone. No differences could be demonstrated between spatial interactions of depressor reflexes evoked by stimulation of somatic or visceral afferents. It seems that the depressor reflex-mechanism operates identically, independently of the input level. The interactions of pressor reflexes were shown to be of the additive type in the case of chloralose or pentobarbital anaesthesia, while of the facilitatory type under urethan anaesthesia. The distribution of spatial interactions of pressor reflexes observed in spinal cats was similar to that observed in animals anaesthetized with chloralose or pentobarbital. The role or various levels of the central nervous system in the organization of spatial interactions of blood pressure reflexes is discussed.

Diabetes insipidus and polycythaemia.

The case of a fourteen year-old boy suffering from diabetes insipidus and polycythaemia is reported. The possible mechanisms resulting in the association of the two rare disorders are discussed in detail.

Spatial interactions of blood pressure reflexes.

Spatial interactions of depressor and pressor reflexes evoked by unilateral and bilateral stimulation of various and somatic afferents were analysed in chloralase-pentobarbital or pentobarbital anaesthetized cats. It has beed found that the dynamics of the spatial interactions can be described by regression equations as a function of the size of the responses evoked by separate stimulation. The angle of inclination and the position of the regression line in the coordinate systems is influenced by the type of reflex, the anaesthetic used and the functional state of the animal. At standard conditions the relations are reproducible. Sagittal splitting of the medulla and the pons did not essentially alter the character of the interaction. The forms of the interactions were unaffected by previous stimulations.

Spatial interactions of opposite vasomotor reflexes.

The simultaneous interactions of pressor and depressor reflexes evoked by stimulation of the central ends of the vagal, tibial and median nerves were studied in urethan and chloralose-urethan anaesthetized cats. The responses obtained to simultaneous activations of opposite reflexes differed from the algebraic sum of the separately evoked ones. The direction and the extent of the differences were determined by the type of the prevailing neural process and by the size of the individual reflex responses. The relations between the responses evoked simultaneously and separately may be characterized by multiple linear regression.

Host-versus-graft disease in mice after the induction of neonatal transplantation tolerance by two different methods.

Newborn A mice were injected either with a single i.v. dose (Group A) or with repeated doses of (B10 x A)F1 semiallogeneic spleen cells (SSC) (Group B). A similar degree of partial transplantation tolerance (TT) to B10 skin allografts was revealed in both groups. No signs of acute, rapidly fatal host-versus-graft disease (HVGD) (anemia, leukocytosis, severe thrombocytopenia, hepatic infarcts, gastrointestinal bleedings) were found, rather a chronic HVGD developed [moderate thrombocytopenia, autoimmune antithymocyte antibodies (ATA)] in both groups. The mortality due to lymphoproliferative disorders (LPD) was significantly higher in Group A. Thus, repeated perinatal injections of (B10 x A)F1 SSC into A mice did not increase the tolerogenic and the LPD-inducing effect either, and they did not elicit acute HVGD in contrast to observations in other F1 donor-recipient combinations [1]. Consequently, the development of acute HVGD depends on immunogenetic factors and not on the repeated administration of SSC.