Abstracts of the twenty-seventh annual meeting of the Japanese society of biometeorology

Prepared by T. Nakayama, President of Japanese Society of Biometeorology, Osaka University Medical School, Kita-ku, Osaka 530, Japan     

Prostaglandin D2 diminishes transmucosal potential difference in rat colonic mucosa in vitro in contrast to the increasing effect of prostaglandin E1

The effect of Prostaglandin D2 (PGD2) on ion transport was investigated in the rat colon in vitro. Ion transport across the intestinal mucosa was estimated by transmucosal potential difference (PD) and short circuit current (Isc) in the Ussing chamber. PGD2 added to the serosal reservoir induced a sustained reduction in PD and Isc at the concentration of higher than 10(-7)M, producing the maximal decrease at 10(-5)M. PGD2 at 10(-5)M completely blocked the increase in PD elicited by prostaglandin E1 (PGE1), theophylline, dibutyryl cAMP or serotonin. Adenylate cyclase activity was determined in the colonic mucosal homogenates after addition of PGD2 and PGE1. Treatment with PGD2 or PGE1 caused a significant increase in the enzyme activity. Combined treatment with both prostaglandins induced no more increase than that elicited by PGE1 alone. These results suggest that PGD2 has an anti-secretory effect on the rat colon and it may regulate the ion transport process through other mechanism than the modification of cyclic AMP concentration in mucosal cells.     

Seasonal variations in the responses of glycolytic intermediates of human erythrocytes to acute cold exposure

Seven male students were studied to observe the effects of acute cold exposure (at 10°C for 60 min) on erythrocyte concentrations of glycolytic intermediates in summer and in winter. The subjects shivered slightly but frankly in both experiments. Significant decreases were observed in the concentrations of pyruvate and lactate during body cooling in summer, but not in winter. The lactate concentration remained significantly reduced 15 min after cold exposure. After 60 min of cold exposure in summer, a negative crossover point appeared to exist between phosphoenolpyruvate and pyruvate and erythrocyte pyruvate kinase activity showed a significant decrease. No seasonal difference was observed in the initial control values of the intermediates measured. From these results and the fact that glucose, pyruvate and lactate are evenly distributed between erythrocytes and plasma, it is likely that erythrocytes and skeletal muscles need less fuel substrate, glucose during cold exposure in winter than in summer, suggesting that an increased economy of energy for homeostasis is achieved.     

Effect of food restriction on cold adaptability of rats

To determine the role of the nutritional state in nonshivering thermogenesis during cold adaptation, cold adaptability was compared between cold-adapted (5 degrees C for 4-5 weeks) rats fed ad libitum and cold-adapted rats pair fed with warm controls having the same food intake. Cold-adapted pair-fed rats suffered a significant loss in body weight during cold exposure. However, brown adipose tissue (BAT) in both cold-adapted ad libitum fed and cold-adapted pair-fed rats was enlarged to the same extent as compared with that in control rats. Fat-free dry matter in BAT also increased in cold-adapted ad libitum fed and cold-adapted pair-fed rats to the same extent. Cold tolerance as assessed by the change in the colonic temperature at -5 degrees C was improved relative to control rats and was the same for cold-adapted ad libitum fed and cold-adapted pair-fed rats. Nonshivering thermogenesis as estimated by the noradrenaline-induced increase in oxygen consumption was significantly greater in the cold-exposed rats and there was no significant difference between cold-adapted ad libitum fed and cold-adapted pair-fed rats. These results suggest that an improved cold tolerance by means of nonshivering thermogenesis in brown adipose tissue is closely related to the low temperature itself but not the increased food intake which occurred in the cold.     

The role of β- and α-adrenoreceptors on blood flow and temperature of brown adipose tissue and involvement of nitric oxide in their effects

1. o

2. 1. Isoproterenol increased interscapular brown adipose tissue (BAT) blood flow and temperature.

3. 2. Phenylephrine increased BAT temperature, but did not affect blood flow. The effect was completely suppressed by N^ω-nitro- -arginine methyl ester ( -NAME), an inhibitor of endogenous NO synthesis.

4. 3. Isoproterenol plus phenylephrine increased BAT blood flow and temperature earlier than isoproterenol alone.

5. 4. CL316,243 increased BAT blood flow and temperature. These effects were also inhibited by -NAME.

6. 5. These data suggest that BAT blood flow as well as thermogenesis is regulated mainly by β-adrenoreceptors and partly by α₁-adrenoreceptors, and NO may be a common mediator for their regulations.

     

Postnatal changes in fatty acids composition of brown adipose tissue

It has been demonstrated that thermogenic activity of brown adipose tissue (BAT) is higher during the early postnatal period, decreasing towards a low adult level. The present study examined postnatal changes in the lipid composition of BAT. BAT from pre-weaning rats at 4 and 14 days old showed the following differences in lipid composition compared to that from adults of 12 weeks old. (i) Relative weight of interscapular BAT to body weight was markedly greater. (ii) BAT-triglyceride (TG) level was lower, while BAT-phospholipid (PL)level was higher. (iii) In TG fatty acids (FA) polyunsaturated fatty acids (PU; mol %), arachidonate index (AI), unsaturation index (UI) and PU/saturated FA (SA) were higher; rare FA such as eicosadienoate, bishomo--linolenic acid and lignoceric acid in mol % were also higher. (iv) In PL-FA monounsaturated FA (MU) in mol % was lower; PU mol %, AI and UI were higher. These features in BAT of pre-weaning rats resembled those in the cold-acclimated adults, suggesting a close relationship of the PL-FA profile to high activity of BAT.     

Expression of cys-cys chemokine ligand 21 on human gingival lymphatic vessels

The cys-cys (C-C) chemokine ligand 21 is a member of the C-C chemokines that constitute a group of heparin-binding cytokines with a pattern of four or six conserved cysteines. The CCL21 is known to be expressed in secondary lymphoid tissues, however it has rarely been reported for the expression on peripheral lymphatic vessels in somatic tissue. Here we investigated the expression of CCL21 on lymphatic vessels identified by anti-desmoplakin in uninflamed and inflamed human gingiva. In uninflamed tissue the expression of CCL21 was detected on lymphatic vessels in gingiva. In uninflamed gingiva the expression of CCL21 was detected on all lymphatic capillaries of the mucosal connective tissue papillae. There were two types of collecting lymphatic vessels in the lamina propria mucosae expressing CCL21 strongly or very weakly. In inflamed gingiva no expression of CCL21 was detected on lymphatic vessels. In all tissue sections no blood vessels expressing CCL21 were observed. These results may suggest that the expression of CCL21 is predominantly induced in the peripheral lymphatic endothelium of the uninflamed mucosal microcirculation, and that under inflamed conditions a reduction of CCL21 occurs in lymphatic endothelium.     

“Vision for Action” in Young Children Aligning Multi-Featured Objects: Development and Comparison with Nonhuman Primates

Effective vision for action and effective management of concurrent spatial relations underlie skillful manipulation of objects, including hand tools, in humans. Children’s performance in object insertion tasks (fitting tasks) provides one index of the striking changes in the development of vision for action in early life. Fitting tasks also tap children’s ability to work with more than one feature of an object concurrently. We examine young children’s performance on fitting tasks in two and three dimensions and compare their performance with the previously reported performance of adult individuals of two species of nonhuman primates on similar tasks. Two, three, and four year-old children routinely aligned a bar-shaped stick and a cross-shaped stick but had difficulty aligning a tomahawk-shaped stick to a matching cut-out. Two year-olds were especially challenged by the tomahawk. Three and four year-olds occasionally held the stick several inches above the surface, comparing the stick to the surface visually, while trying to align it. The findings suggest asynchronous development in the ability to use vision to achieve alignment and to work with two and three spatial features concurrently. Using vision to align objects precisely to other objects and managing more than one spatial relation between an object and a surface are already more elaborated in two year-old humans than in other primates. The human advantage in using hand tools derives in part from this fundamental difference in the relation between vision and action between humans and other primates.