Induction of endothelial nitric-oxide synthase in rat brain astrocytes by systemic lipopolysaccharide treatment

In the brain, three isoforms of nitric oxide (NO) synthase (NOS), namely neuronal NOS (nNOS, NOS1), inducible NOS (iNOS, NOS2), and endothelial NOS (eNOS, NOS3), have been implicated in biological roles such as neurotransmission, neurotoxicity, immune function, and blood vessel regulation, each isoform exhibiting in part overlapping roles. Previous studies showed that iNOS is induced in the brain by systemic treatment with lipopolysaccharide (LPS), a Gram-negative bacteria-derived stimulant of the innate immune system. Here we found that eNOS mRNA is induced in the rat brain by intraperitoneal injection of LPS of a smaller amount than that required for induction of iNOS mRNA. The induction of eNOS mRNA was followed by an increase in eNOS protein. Immunohistochemical analysis revealed that eNOS is located in astrocytes of both gray and white matters as well as in blood vessels. Induction of eNOS in response to a low dose of LPS, together with its localization in major components of the blood-brain barrier, suggests that brain eNOS is involved in early pathophysiologic response against systemic infection before iNOS is induced with progression of the infection.     

Head-down bed rest alters sympathetic and cardiovascular responses to mental stress

Astronauts usually work under much mental stress. However, it is unclear how and whether or not an exposure to microgravity affects physiological response to mental stress in humans. To examine effects of microgravity on vasomotor sympathetic and peripheral vasodilator responses to mental stress, we performed 10 min of mental arithmetic (MA) before and after 14 days of 6 degrees head-down bed rest (HDBR), a ground-based simulation of spaceflight. Total muscle sympathetic nerve activity (MSNA, measured by microneurography) slightly increased during MA before HDBR, and this increase was augmented after HDBR. Calf blood flow (measured by venous occlusion plethysmography) increased and calf vascular resistance (calculated by dividing mean blood pressure by calf blood flow) decreased during MA before HDBR, but these responses were abolished after HDBR. Increases in heart rate and mean blood pressure during MA were not different between before and after HDBR. These findings suggest that HDBR augmented vasomotor sympathoexcitation but attenuated vasodilatation in the calf muscle in response to mental stress.     

Analysis of the microheterogeneity of the IgA1 hinge glycopeptide having multiple O-linked oligosaccharides by capillary electrophoresis

It was found that the self-aggregation of IgA1 was closely connected with the glycoform of a mucin-type sugar chain on its hinge portion. In this report, normal human serum IgA1 was separated into two subfractions by a jacalin column. The elution condition, 25 mM galactose, used here was similar to that reported for the glycoprotein with a single mucin-type sugar chain per molecule. The IgA1 eluted under this condition was substantially the monomeric form. In contrast, the remaining IgA1 eluted from the column with 0. 8 M galactose was substantially the aggregated form. An analytical method for the microheterogeneity of the IgA1 hinge glycopeptide (HGP33) was developed to determine the difference between these IgA1 fractions by capillary electrophoresis (CE). Native HGP33 from both IgA1 fractions was separated into peaks 1-11, depending on their glycoforms. Because the sialic acid-rich component migrated slowly on CE, the 25 mM fraction was abundant in the sialic acid-rich components (peaks 7-11), but the 0.8 M fraction was abundant in the sialic acid-poor components (peaks 1-4). Comparison of the number of sugar chains per hinge peptide indicated that the 25 mM fraction was relatively well glycosylated. Thus, application of CE analysis to the HGP33 indicated that the monomeric IgA1 was composed of a relatively complete molecule with respect to the glycoform rather than the aggregated IgA1.     

Characterization of a secretase activity for placental leucine aminopeptidase

Placental leucine aminopeptidase (P-LAP) is believed to play an important role in the inactivation of small regulatory peptides. P-LAP exists in both membrane-bound and soluble forms and cDNA cloning has demonstrated that P-LAP is a type II membrane protein, which means that its soluble form is released by a specific proteolytic cleavage. In this report, we studied this process in COS7 cells. Inhibitors of serine or aspartic proteases did not affect the secretion of P-LAP, while EDTA and 1,10-phenanthroline inhibited it. In addition, we transfected P-LAP expression vectors that have point mutations of the cleavage site or deletion of the juxtamembrane stalk. Point mutations of the cleavage site resulted in significantly lower secretion of P-LAP. On the contrary, the distance to cleavage site showed no relation to P-LAP secretion. These results suggest that P-LAP secretase has a metalloprotease activity which depends on the amino acid sequence of the cleavage site.     

No effects of acclimation to heat on immune and hormonal responses to passive heating in healthy volunteers

Heat acclimation results in whole body-adaptations that increase heat tolerance, and might also result in changed immune responses. We hypothesized that, after heat acclimation, tumor necrosis factor alpha, interleukin 6 and the lymphocyte count would be altered. Heat acclimation was induced in 6 healthy men by 100 min of heat exposure for 9 days. Heat exposure consisted of (1) 10 min of immersion up to chest-level in water at 42°C and (2) 90 min of passive heating by a warm blanket to maintain tympanic temperature at 37.5°C. The climatic chamber was maintained at 40°C and a relative humidity of 50%. Blood samples were analyzed before and after heat acclimation for natural killer (NK) cell activity, counts of lymphocytes B and T, before and after heat acclimation for peripheral blood morphology, interleukin 6, tumor necrosis factor alpha, and cortisol. A Japanese version of the profile of mood states questionnaire was also administered before and after acclimation. The concentrations of white blood cells, lymphocytes B and T, cortisol, interleukin 6, tumor necrosis factor alpha and NK cell activity showed no significant differences between pre- and post-acclimation, but there was a significantly lower platelet count after acclimation and, with the profile of mood states questionnaire, there was a significant rise in anger after acclimation. It is concluded that heat acclimation by passive heating does not induce alterations in immune or endocrine responses.     

Gender disparities in the association between epicardial adipose tissue volume and coronary atherosclerosis: A 3-dimensional cardiac computed tomography imaging study in Japanese subjects

ABSTRACT: BACKGROUND: Growing evidence suggests that epicardial adipose tissue (EAT) may contribute to the development of coronary artery disease (CAD). In this study, we explored gender disparities in EAT volume (EATV) and its impact on coronary atherosclerosis. METHODS: The study population consisted of 90 consecutive subjects (age: 63 +/- 12 years; men: 47, women: 43) who underwent 256-slice multi-detector computed tomography (MDCT) coronary angiography. EATV was measured as the sum of cross-sectional epicardial fat area on CT images, from the lower surface of the left pulmonary artery origin to the apex. Subjects were segregated into the CAD group (coronary luminal narrowing > 50%) and non-CAD group. RESULTS: EATV/body surface area (BSA) was higher among men in the CAD group than in the non-CAD group (62 +/- 13 vs. 33 +/- 10 cm3/m2, p < 0.0001), but did not differ significantly among women in the 2 groups (49 +/- 18 vs. 42 +/- 9 cm3/m2, not significant). Multivariate logistic analysis showed that EATV/BSA was the single predictor for >50% coronary luminal narrowing in men (p < 0.0001). Predictors excluded were age, body mass index, hypertension, diabetes mellitus, and hyperlipidemia. CONCLUSIONS: Increased EATV is strongly associated with coronary atherosclerosis in men.     

Phosphodiesterase inhibitors. Part 4: Design, synthesis and structure-activity relationships of dual PDE3/4-inhibitory fused bicyclic heteroaromatic-4,4-dimethylpyrazolones

(-)-6-(7-Methoxy-2-trifluoromethylpyrazolo[1,5-a]pyridin-4-yl)-5-methyl-4,5-dihydro-3-(2H)-pyridazinone (KCA-1490) is a dual PDE3/4 inhibitor that exhibits potent combined bronchodilatory and anti-inflammatory activity. Here we show that a 4,4-dimethylpyrazolone subunit serves as an effective surrogate for the 5-methyl-4,5-dihydropyridazin-3(2H)-one ring of KCA-1490 whilst lacking a stereogenic centre. The 2- and 7-substituents in the pyrazolo[1,5-a]pyridine subunit markedly influence the PDE-inhibitory profile and can be adjusted to afford either potent PDE4-selective inhibitors or dual PDE3/4 inhibitors. A survey of bicyclic heteroaromatic replacements for the pyrazolo[1,5-a]pyridine allowed further refinement of the inhibitory profile and identified 3-(8-methoxy-2-(trifluoromethyl)imidazo[1,2-a]pyridin-5-yl)-4,4-dimethyl-1H-pyrazol-5(4H)-one as an orally active, achiral KCA-1490 analog with well-balanced dual PDE3/4-inhibitory activity.     

Developmental processes of achlorophyllous orchid, <Emphasis Type="Italic">Epipogium roseum</Emphasis>: from seed germination to flowering under symbiotic cultivation with mycorrhizal fungus

We have achieved the symbiotic cultivation of an apparently achlorophyllous orchid, Epipogium roseum Lindl., with a mycorrhizal fungus isolated from an underground organ of this orchid. Although the seed germination rate was extremely low, subsequent growth from protocorm to flowering was induced in a medium containing volcanic soils and sawdust. Stolons elongated from each protocorm, and rhizomes were formed at certain intervals on the stolons. Some of the rhizomes developed into a coralloid form, and tubers were formed from the coralloid rhizomes. The coralloid rhizomes degenerated concurrently with maturation of the tubers. Six months after seed sowing, around 80 tubers were produced from a single protocorm. An inflorescence appeared from each of the large tubers, and the process to flowering was observed in one of these. Consequently, the developmental processes from seed to flowering in E. roseum was clearly revealed in this study.     

Hypoxic ventilatory response during light and dark periods and the involvement of histamine H1 receptor in mice

Ventilation oscillates throughout a day in parallel with oscillations in metabolic rate. Histamine affects ventilation and the balance of the energy metabolism via H1 receptors in the brain. We tested the hypothesis that the ventilatory response to hypoxia varies between light and dark periods and that histamine H1 receptors are required for the circadian variation, using wild-type (WT) and histamine H1 receptor knockout (H1RKO) mice. Mice were exposed to hypoxic gas (7% O(2) + 3% CO(2) in N(2)) during light and dark periods. Ventilation initially increased and then declined. In WT mice, minute ventilation (.Ve) during hypoxia was higher in the dark period than in the light period, which was an upward shift along with the baseline ventilation. Hypoxia decreased the metabolic rate, whereas O2 consumption (.VO(2)) and CO(2) excretion were higher in the dark period than in the light period. However, in H1RKO mice, changes in Ve during hypoxia between light and dark periods were minimal, because .Ve was increased relative to .VO(2), particularly in the light period. In H1RKO mice, the HCO(3)(-) concentration and base excess values were increased in arterial blood, and the level of ketone bodies was increased in the serum, indicating that metabolic acidosis occurred. Respiratory compensation takes part in the .Ve increase relative to .VO(2) during hypoxia. These results suggested that changes in .Ve during hypoxia vary between light and dark periods and that H1 receptors play a role in circadian variation in .Ve through control of the acid-base status and metabolism in mice.     

Effects of immersion in water containing high concentrations of CO2 (CO2-water) at thermoneutral on thermoregulation and heart rate variability in humans

Immersion in high concentrations of CO₂ dissolved in freshwater (CO₂-water) might induce peripheral vasodilatation in humans. In this study, we investigated whether such immersion could affect the autonomic nervous system in humans using spectral analysis of heart rate variability. Ten healthy men participated in this study. Tympanic temperature, cutaneous blood flow and electrocardiogram (ECG) were measured continuously during 20 min of immersion in CO₂-water. The ECG was analyzed by spectral analysis of R–R intervals using the maximal entropy method. The decrease in tympanic temperature was significantly greater in CO₂-water immersion than in freshwater immersion. Cutaneous blood flow at the immersed site was significantly increased with CO₂-water immersion compared to freshwater. The high frequency component (HF: 0.15–0.40 Hz) was significantly higher in CO₂-water immersion than in freshwater immersion, but the low frequency (LF: 0.04–0.15 Hz) /high frequency ratio (LF/HF ratio) was significantly lower in CO₂-water immersion than in freshwater immersion. The present study contributes evidence supporting the hypothesis that CO₂-water immersion activates parasympathetic nerve activity in humans.