Anoxic disturbance of the isolated respiratory network of neonatal rats

Tissue oxygen (PO₂), K⁺ (aK_e), pH (pH_e) and Ca²⁺ ([Ca²⁺]_e) were measured in the region of the ventral respiratory group (VRG) in the in vitro brainstem-spinal cord preparation of neonatal rats. During tissue anoxia, elicited by superfusion of N₂-gassed solutions, an initial increase in the frequency of respiratory activity, lasting between 2 and 12 min, turned into a frequency depression. During anoxia periods of up to 60 min, respiratory activity persisted in solutions containing CO₂/bicarbonate, whereas a complete blockade was observed after 15–25 min in N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid- (Hepes)-buffered salines. After such anoxic apnea, respiratory rhythmicity could be reactivated by superfusion of hypoxic, CO₂/bicarbonate-buffered solutions. In both types of hypoxic solutions, aK_e increased by maximally 1.5mM, whereas an initial increase of pH_e by up to 0.05 pH units turned, after 2–4 min, into an acidification which could exceed 0.5 pH units. In contrast, [Ca²⁺]_e remained unaffected by anoxia. Addition of 2–5 mM cyanide (CN^-) to oxygenated Hepes-buffered saline evoked an increase in PO₂ in the VRG from 100 to more than 300 mmHg. The effects of CN^- on respiratory activity, aK_e and pH_e were almost identical to those during anoxia. In oxygenated, CO₂/bicarbonatefree solutions of different pH, however, an increase in pH_e in the VRG led to a decrease in respiratory frequency, whereas a fall of pH_e produced a frequency acceleration. A rise of aK_e in the VRG by more than 2 mM as induced by superfusion of a 7 mM K⁺ solution led to a sustained increase of respiratory frequency. The results indicate that blockade of aerobic metabolism does not severely perturb K⁺ and Ca²⁺ homeostasis and that the biphasic response to anoxia is not directly related to the observed changes in PO₂, aK_e, pH_e, or [Ca²⁺]_e. In the respiratory network of neonatal mammals, CO₂ might provide a stimulus for long-term maintenance of respiratory activity under oxygen depletion.     

Reorganisation of respiratory network activity after loss of glycinergic inhibition

gamma-Aminobutyric acid (GABA)-ergic and glycinergic inhibition is believed to play a major role in the respiratory network. In the present study we tested whether specific blockade of glycinergic inhibition resulted in changes in respiratory network interaction and function. Using the working heart-brainstem preparation from adult mice, we recorded phrenic nerve activity and the activity of different types of respiratory neurones located in the ventrolateral medulla. Strychnine (0.03-0.3 microM) was given systemically to block glycine receptors (Gly-R). During exposure to strychnine, post-inspiratory (PI) neurones shifted their onset of discharge into the inspiratory phase. As a consequence, the post-inspiratory phase failed and the rhythm changed from a three-phase cycle (inspiration, post-inspiration, expiration, with a frequency of about. 0.24 Hz) to a faster, two-phased cycle (inspiration expiration, frequency about 0.41 Hz). Inspiratory and expiratory neurones altered their augmenting membrane potential pattern to a rapidly peaking pattern. Smaller voltage oscillations at approximately 10 Hz and consisting of excitatory and inhibitory postsynaptic potential sequences occurred during the expiratory interval. Due to their high frequency and low amplitude, such oscillations would be inadequate for lung ventilation. We conclude that, under physiological conditions, glycinergic inhibition does indeed play a major role in the generation of a normal respiratory rhythm in adult mice. After failure of glycinergic inhibition a faster respiratory rhythm seems to operate through reciprocal GABAergic inhibition between inspiratory and expiratory neurones, while phase switching is organised by activation of intrinsic membrane properties.     

Microembolic Renal Disease in Rats Induced with Sephadex: Hypertension, Lesions and Serum Urea Nitrogen

Sephadex particles (20-80 μ in size) were injected into the abdominal aorta of 134 male Sprague-Dawley rats near the renal arteries. In 31 rats, the right kidney was then removed. The Sephadex particles lodged in glomerular capillaries, afferent glomerular arterioles and interlobular arteries, creating renal infarcts, some of which were grossly visible. Shortly after injection, arterial blood pressure rose significantly in most animals. The hypertension in uninephrectomized rats was not demonstrably different from that in rats with two Kidneys. Severity and duration of hypertension (up to 8 months) were positively correlated with the number of Sephadex particles in renal vessels, and there was also a positive correlation between the degree of hypertension and serum urea nitrogen levels, and between degree of hypertension and degree of cardiac hypertrophy. The vascular permeability in acutely hypertensive rats was abnormal, as judged from penetration of iron-dextran into vessel walls. This experimental model resembles atheromatous microembolic renovascular disease, which may play a significant role in the pathogenesis of unexplained hypertension in patients with advanced aortic atherosclerosis.     

Immunoglobulin determinants on the surface of lymphoid cells of carps.

Immunoglobulin determinants were detected by indirect immunofluorescence on the surface of numerous lymphocytes of perpheral blood, spleen, and pronephros of craps. The most interesting finding was the high proportion (65–68 %) of Ig⁺ lymphocytes in the thymus of early adult carps, possibly related to thymus function.     

Cells involved in the immune response. XXX. An evaluation of the different assays to demonstrate rabbit spleen plaque-forming cells. Enhancement of the assay by anti-target cell antibodies

Four different procedures for the detection of rabbit spleen plaque-forming cells (PFC) directed toward the sheep erythrocyte (SRBC) antigen were evaluated in terms of their sensitivity. These included the conventional localized hemolysis in gel (LHG) assay, the thin-layer LHG assay, the LH assay using a monolayer of the target SRBC erythrocytes and the localized hemolysis in liquid phase (Cunningham) assay. The latter assay consistently proved to be the most sensitive assay. The sensitivity of this latter assay was further improved by incorporating preformed IgG or IgM antibodies directed toward the target erythrocytes, in subhemolytic concentrations, into the assay. This antibody-enhanced plaque assay in liquid medium is 20-50 times more sensitive than the conventional LHG assay.     

Ca2+–calmodulin-dependent protein kinase expression and signalling in skeletal muscle during exercise

Ca²⁺ signalling is proposed to play an important role in skeletal muscle function during exercise. Here, we examined the expression of multifunctional Ca²⁺–calmodulin-dependent protein kinases (CaMK) in human skeletal muscle and show that CaMKII and CaMKK, but not CaMKI or CaMKIV, are expressed. Furthermore, the effect of exercise duration and intensity on skeletal muscle CaMKII activity and phosphorylation of downstream targets was examined. Eight healthy men exercised at ∼67% of peak pulmonary O₂ uptake     with muscle samples taken at rest and after 1, 10, 30, 60 and 90 min of exercise. Ten other men exercised for three consecutive 10 min bouts at 35%, 60% and 85%     with muscle samples taken at rest, at the end of each interval and 30 min post-exercise. There was a rapid and transient increase in autonomous CaMKII activity and CaMKII phosphorylation at Thr²⁸⁷ in skeletal muscle during exercise. Furthermore, the phosphorylation of phospholamban (PLN) at Thr¹⁷, which was identified as a CaMKII substrate in skeletal muscle, was rapidly (< 1 min) increased by exercise, and remained phosphorylated 5-fold above basal level during 90 min of exercise. The phosphorylation of serum response factor at Ser¹⁰³, a putative CaMKII substrate, was higher after 30 min of exercise. PLN phosphorylation at Thr¹⁷ was higher with increasing exercise intensities. These data indicate that CaMKII is the major multifunctional CaMK in skeletal muscle and its activation occurs rapidly and is sustained during continuous exercise, with the activation being greater during intense exercise.     

Significance of laboratory diagnostic study parameters of the hepatobiliary system in the evaluation of cardiovascular diseases--results of cross sectional and longitudinal studies in patients with suspicious cardiovascular findings in an epidemiologic follow-up study

With the help of an approx. 280 000 inhabitants check of x-ray-morphological suspects of a heart disease the laboratory parameters thymol turbidity test, zinc-sulphate turbidity test, total protein, serum protein electrophoresis and the enzymes "ASAT" and "ALAT" in longitudinal section and cross-section were examined in an intervention study during 5 years. All these parameters show standard values on the average, but compared to a healthy reference they showed significant differences, which relations to heart and vessel diseases could be deduced from. This referred especially to age-inverse behaviour of the transaminases only concerning male test persons. The examination of the longitudinal section confirmed exactly the results of the cross-section analysis. On the one hand it underlines the results got from the cross-section and in the second place it contributes to the efficient diagnostics by learning undone a repetition of these laboratory examinations during the period of 5 years with such a defined population. The relations of the particularities mentioned obviously refer to subclinical fields. Effects of therapy do not reflect in the laboratory findings.