Correlation between ventilation and brain blood flow during hypoxic sleep

Ventilation and brain blood flow (BBF) were simultaneously measured during carbon monoxide (CO) inhalation in awake and sleeping goats up to HbCO levels of 40%. Unilateral BBF, which was continuously measured with an electromagnetic flow probe placed around the internal maxillary artery, progressively increased with CO inhalation in the awake and both sleep stages. The increase in BBF with CO inhalation during rapid-eye-movement (REM) sleep (delta BBF/delta arterial O2 saturation = 1.34 +/- 0.27 ml X min-1 X %-1) was significantly greater than that manifested during wakefulness (0.87 +/- 0.14) or slow-wave sleep (0.92 +/- 0.13). Ventilation was depressed by CO inhalation during both sleep stages but was unchanged from base-line values in awake goats. In contrast to slow-wave (non-REM) sleep, the ventilatory depression of REM sleep was primarily due to a reduction in tidal volume. Since tidal volume is more closely linked to central chemoreceptor function, we believe that these data suggest a possible role of the increased cerebral perfusion during hypoxic REM sleep. Induction of relative tissue alkalosis at the vicinity of the medullary chemoreceptor may contribute to the ventilatory depression exhibited during this sleep period.     

Correlation between the dopamine-beta-hydroxylase activity and the level of plasma catecholamines during muscular exercise]

The plasma dopamine-beta-hydroxylase activity was measured in 10 healthy untrained volunteers during a graded physical exercise on a bicycle ergometer. The authors have shown a good correlation between the DbetaH activity and the noradrenaline content in plasma. It can therefore be concluded that the DbetaH activity could be a true measure of the sympathetic activity.     

Correlation between serum alkaline phosphatase activity and blood glucose levels

Fasting blood glucose levels and serum alkaline phosphatase activity of age-matched Libyan diabetic men (168) and women (168) were determined. The mean levels of blood glucose of men and women were 227 +/- 6 and 237 +/- 5 mg/dl, respectively. The respective values of serum alkaline phosphatase were 179 +/- 5 and 199 +/- 6 IU/l. The mean serum phosphatase activity of women was significantly higher (p less than 0.001) than that of their male counterparts. A statistically significant positive correlation was found between serum alkaline phosphatase and blood glucose levels of these diabetic patients (r = 0.35; p less than 0.001).     

Effect of scopolamine on formation and fixation of temporary connections in rats with altered brain serotonin levels

The influence of scopolamine on elaboration and maintenance of conditioned reflexes of two-way avoidance was studied in rats under conditions of excess and deficit of serotonin in the brain. Administration of scopolamine to intact rats accelerated conditioning and did not prevent fixation of the reflex. Administration of scopolamine to animals with a lowered level of serotonin in the brain (by means of para-chlorophenylalanine) impaired conditioning and induced amnesia. In animals with ablated raphe nuclei, the same dose of scopolamine did not prevent elaboration and maintenance of conditioned reflexes. Accumulation of scopolamine in the brain by means of 5-oxytryptophan abolished acceleration of conditioning, which is specific for scopolamine, and affected the preservation of the reflexes. Against the background of the action of iprozid, scopolamine impaired the conditioning and tended to deteriorate the maintenance of conditioned reflexes. It is assumed that the serotoninergic system exerts a modulating influence on the activity of the brain cholinergic and cholinoreactive mechanisms.     

Correlation between cyclic AMP levels and calcium efflux in isolated renal cortical tubules.

Isolated renal cortical tubules from male hamsters were utilized to examine the possible relationship between cyclic AMP (cAMP) and efflux of calcium. Both parathyroid hormone (PTH) and prostaglandin E1 (PGE1) produced dose-related increases in cAMP levels and calcium efflux from isolated tubules. Maximal concentrations of both hormones resulted in changes in cAMP which were 6 fold greater and changes in calcium efflux which were 2 fold greater with PGE1 than with PTH. Effects of sub-maximal amounts of either hormone on both cAMP and calcium efflux were potentiated to tubule incubations resulted in increases in tissue-associated cAMP over the same degree by inclusion of methyl-isobutylxanthine (MIX). Addition of either exogenous cAMP or dibutyryl cAMP (db-cAMP) produced dose-related increases in calcium efflux which occurred more rapidly with db-cAMP than with cAMP. Increasing amounts of cAMP added to the same concentration range resulting in increases in calcium efflux. Addition of 2', 3' cyclic AMP, 5'AMP or db-cyclic GMP had no significant effect on calcium efflux while 3', 5' cyclic CMP significantly reduced this response. The results indicate that cAMP increases efflux of calcium from renal tubules and may play a central role in hormone-dependent transport of this ion.     

衰老性记忆障碍与脑突触体内游离[Ca^2＋]i的相关性

采用行为观察和生化检测相结合的方法,在过去工作的基础上,研究了１２月龄和１８月龄小鼠学习记忆能力的变化和１８月龄小鼠四个脑区（海马、大脑皮层、四叠体和小脑）交触体内「Ｃａ＾２＋」ｉ的水平,同时还比较了老年记忆保持良好组与记忆障碍组小鼠的脑钙水平。结果表明,随着年龄的增长,小鼠的学习记忆能力显著下降,上述脑区（除大脑皮层外）突触内「Ｃａ＾２＋」ｉ均明显升高,其中老年记忆障碍小鼠脑钙水平升高最为显著。     

Effect of gonadectomy on brain catecholamines during the postnatal period

The effect produced by gonadectomy on dopamine (DA) and noradrenaline (NA) levels in the diencephalon and the rest of the brain of male and female rats during postnatal development has been studied. DA and NA metabolism or biosynthesis seems to be regulated by the ovarian hormones, directly or by means of hypophysary hormones, since both catecholamine levels rise acutely during postnatal development when ovariectomy is performed. In contrast with controls, the NA level is not stable at 45 days, but continues rising to day 60. Orchidectomy also acutely increases the level of diencephalic DA, but in contrast with females, its concentration progressively decreases, being at day 60 the same as in the controls. The reasons that cause this normalization, in the absence of testicular androgens, are unknown. In the same way, the extirpation of the testicles increases the diencephalic concentration of NA, the concentration change is similar to the control one: however, the level is higher. There is also a clear difference from the gonadectomized females, in which the diencephalic NA rises during 45-60 days. Gonadectomy does not significantly alter the level of DA or NA in the rest of the brain.     

Correlation between release of free arachidonic acid and prostaglandin formation in brain cortex and cerebellum

Levels of free arachidonic acid and of prostaglandin F_2α and E₂ have been measured in both brain cortex and cerebellum of rats killed by focussed microwave irradiation, and after decapitation followed by ischemia. The same parameters were studied during incubation assays. It was found that: a) after ischemia levels of both free arachidonic acid and of prostaglandins in cerebellum are lower than in brain cortex, b) formation of prostaglandins from endogenous precursor in incubated cortex is higher than in cerebellum, c) release of free arachidonic acid occurs mainly during the time interval between the sacrifice of the animals and the beginning of the incubation, whereas prostaglandins are formed mainly during the incubation assay. The correlation between release of free arachidonic acid and prostaglandin formation is discussed.     

Influence of thyroidectomy on brain catecholamines during the postnatal period

The influence of early thyroidectomy (Tx) on changes in dopamine (DA) and noradrenaline (NA) during the postnatal period (30, 45 and 60 days old) was studied in the diencephalon and the rest of the brain of male and female rats. Thyroidectomy interfered with the normal growth of the animals, decreased brain weight and markedly influenced the developmental pattern of both DA and NA in the diencephalon. When compared with control values, the DA concentration, in 45- and 60-day-old Tx male rats, was 29 and 43% lower, respectively, and 21 and 43% lower, respectively, in Tx females. Diencephalic NA levels in Tx rats were also lower than those observed in controls, 15% inferior in 45- and 60-day-old males; 27 and 22% lower, respectively, in females. Thyroidectomy does not significantly alter the level of either amine in the rest of the brain.     

Dietary calcium and blood lead levels in women

Nutritional factors are known to influence metabolism and toxicity of several metals in animal experiments, but relevant human data are scarce and inconclusive. In this work, we tested the hypothesis that dietary calcium influences lead metabolism in humans. Blood lead concentrations were used as indicators of lead exposure and metabolism. Two groups of peasant women living in similar conditions in two different regions in Yugoslavia (100 in each) were chosen as subjects for this purpose. In region A, the dietary calcium intake was about 940 mg, and in region B about two times lower, i.e., 450 mg/day. The average blood lead concentration was significantly lower in women from region A (69 micrograms/L) than from region B (83 micrograms/L). Our results support the assumption that adequate calcium intake might be one of the preventive measures for decreasing lead absorption. This new evidence, sought for some time by nutritionists and toxicologists, needs further international confirmation.     

Relationship between levels of brain natriuretic peptide in blood and immune response in subjects

Elevated concentrations of Nt-pro-BNP were revealed in 11% of apparently healthy subjects aged 19–24 years and 22% of middle-aged (34–55 years) subjects. An increase in Nt-pro-BNP blood concentration was detected in 90% of patients with metabolic syndrome. Elevated levels of Nt-pro-BNP in peripheral blood occur with age. Higher concentrations of the peptide were revealed in women. Inhibition of lymphocytes proliferation and differentiation accompanied by increasing concentration of Nt-pro-BNP in blood is associated with a deficiency of the IL-2 level due to increased IL-10 concentration. Immunosuppressive effect of IL-10 declares itself at the level of innate immune reactions as a decrease in blood counts of naive CD45RA+ T lymphocytes, natural killer cells, T cells with adhesion receptor (CD56+) and adhesion receptor ligand (CD62L+). To prevent a loss of the intercellular pool, the effect of Nt-pro-BNP is activated. No statistically significant correlations between the increased Nt-pro-BNP concentration in blood and the content of serum IgM, IgG, IgA, IgE, IL-6, TNF-α, IFN-γ, CEC C1q, or С3d, as well as glucose, hemoglobin, transferrin, iron, or free fatty acids were revealed in apparently healthy subjects.     

Correlation between the steady state and turnover of gamma-aminobutyric acid during brain maturation in mice

In 2 inbred strains of mice (C57Bl/6J, DBA/2J) in 15 areas, the in vivo GABA turnover rates are significantly correlated with the GABA steady-state levels in 21 day-old mice. In 3 month-old mice the correlation stands only in some areas, the same ones in the 2 strains: olfactory bulbs, frontal cortex, septum, amygdala, hypothalamus, hippocampus, cerebellum. Moreover, the turnover rates decrease sharply with age.     

The brain catecholamines during domestication of the silver fox Vulpes fulvus

Studies have been made on the content of catecholamines (noradrenaline and dopamine) as well as metabolites of dopamine (3,4-dihydroxyphenylacetic and homovanillic acids) in the brain structures of silver foxes which differ in their handling reactions. The level of noradrenaline was found to be significantly higher in the anterior hypothalamus of domesticated animals; no differences in noradrenaline content were found in the frontal cortex, hippocamp, posterior hypothalamus and midbrain in animals from aggressive and domesticated groups. Dopamine content was higher in the tuberculum olfactorium of domesticated animals, being lower in the striatum and n. accumbens. Metabolite level remained unaffected which is presumably due to changes in dopamine synthesis in the investigated structures. It was concluded that domestication of animals favours the specimens with an altered state of catecholaminergic system of the brain.     

Correlation between the rhythms of blood insulin levels and the stimulation of spleen lymphocytes by concanavalin-A in mice

An ultradian rhythm of DNA synthesis and an in-vitro response to Concanavalin-A (Con-A) stimulation has been found in splenocytes of DBA/2 male mice, living under conditions standardized for light-synchronized periodicity. It was characterized by two peaks during the nycthemeral cycle. One of them was very sharp. In spite of a constant mode of synchronization of the animals, there were seasonal variations of the rhythm. Such variations did not, however, affect the position of the sharp peak, which occurred always at the same hour. The rhythm of incorporation of [3H]-thymidine by splenocytes, whether or not stimulated by Con-A, seemed correlated with that of blood insulin levels in mice. The possible effect of the physiological increase in blood insulin during the circadian cycle has been confirmed experimentally. Thus it seems probable that insulin would be one of the internal synchronizers .