Intensely positively charged perineuronal nets in the adult rat brain as detected by staining with anionic iron colloid

Ferric chloride, when boiled with ammonium thiocyanate, ammonia and cacodylic acid, is converted into a fine anionic iron colloid which consists of 1.0-1.5 nm electron dense granules and gives a distinct Prussian blue reaction (OHTSUKA and MURAKAMI, 1986). Light microscopy of tissue sections stained with this fine anionic iron colloid at pH values of 6.0, 7.0 and 8.0 showed that the healthy adult rat brain contains a considerable number of neurons which possess an intensely positively charged perineuronal net. This net was most clearly demonstrable by staining with the anionic iron colloid at a pH value of 8.0, at which ionizations of almost all cationic sites of the tissue elements were obliterated. Transmission electron microscopy of ultrathin sections stained at a pH value of 8.0 showed that the anionic iron colloid was preferentially deposited in the perineuronal tissue spaces. These findings indicate that the intensely positively charged perineuronal net contains some strongly basic substances such as guanidino compounds, and occupies the perineuronal (perisynaptic) tissue space.     

Copper and iron-induced oxidative damage in non-tumor bearing LEC rats

The copper and Iron status in the liver of non-tumor bearing Long-Evans Cinnamon (LEC) rats (average age 17 months) was investigated. A direct quantitation of loosely-bound copper and iron was also investigated by using a chelating agent, nitrilotriacetic acid (NTA-chelatable free copper and iron). Besides the total copper and iron contents, the level of NTA-chelatable free copper was also higher in LEC rats than In LEA rats (P<0.05). But for the free iron level there was no signiflcant difference between the two rat groups (P>0.05). The formation of thiobarbituric acid-reactive substances was higher In LEC rats than In LEA rats (P<0.01). The 4–hydroxy-2–nonenal (HNE)-modified proteins were also clearly demonstrated in LEC rat liver. The copper and iron which produced the most important effect In the process of oxidative damage in LEC rats could not be distinguished. Even though free copper, which could induce free radical injuries, was increased in LEC rats, neither tumor-induction nor preneo-plastic lesions in the experimental LEC rats were observed. Therefore it is speculated that the elevation of a free iron is another important factor. Copper and iron, both important translation metals In the body, may participate In the Induction of DNA damage and oncogenesls     

T-cell-specific expression of kinase-defective Eph-family receptor protein, EphB6 in normal as well as transformed hematopoietic cells

Although most kinase-defective growth factor receptor proteins are associated with pathogenic conditions, a kinase-defective Eph-family receptor protein, EphB6, is expressed in normal human tissues. We generated monoclonal antibodies specific for human EphB6 to characterize its expression on human hematopoietic cells. A very small population of normal human peripheral white blood cells (0.57 +/- 0.07%, n = 12) expressed EphB6. The EphB6-positive cells were CD2+, CD7+, CD3+ and CD4+ or CD8+ lymphocytes, but they did not express CD19 or CD11b. In human bone marrow, only 1.5 +/- 0.19% of lymphocytes expressed EphB6. Compared with the expression in peripheral lymphocytes, prominent expression of EphB6 protein was demonstrated in CD4+CD8+ double-positive mouse thymocytes. The T-cell lineage-specific expression was strictly conserved in human leukemia/lymphoma cells. Among T-cell-derived leukemia cells, the expression level of EphB6 seemed to decrease with maturation of the cells. These results suggest that EphB6 expression is regulated in T-cell development.     

Altered EphA5 mRNA expression in rat brain with a single methamphetamine treatment

Methamphetamine is a potent and indirect dopaminergic agonist which can cause chronic brain dysfunctions including drug abuse, drug dependence and drug-induced psychosis. Methamphetamine is known to trigger molecular mechanisms involved in associative learning and memory, and thereby alter patterns of synaptic connectivity. The persistent risk of relapse in methamphetamine abuse, dependence and psychosis may be caused by such alterations in synaptic connectivity. EphA5 receptors constitute large families of tyrosine kinase receptor and are expressed almost exclusively in the nervous system, especially in the limbic structures. Recent studies suggest EphA5 to be important in the topographic projection, development, and plasticity of limbic structures, and to be involved in dopaminergic neurotransmission. We used in situ hybridization to examine whether methamphetamine alters EphA5 mRNA expression in the brains of adult male Wister rats. EphA5 mRNA was widely distributed in the medial frontal cortex, cingulate cortex, piriform cortex, hippocampus, habenular nucleus and amygdala. Compared to baseline expression at 0 h, EphA5 mRNA was significantly decreased (by 20%) in the medial frontal cortex at 24 h, significantly increased (by 30%) in the amygdala at 9 and 24 h, significantly but transiently decreased (by 30%) in the habenular nucleus at 1 h after a single injection of methamphetamine. Methamphetamine did not change EphA5 mRNA expression in the cingulate cortex, piriform cortex or hippocampus. Our results that methamphetamine altered EphA5 mRNA expression in rat brain suggest methamphetamine could affect patterns of synaptic connectivity, which might be responsible for methamphetamine-induced chronic brain dysfunctions.     

Novel immunosuppressive effect of FK506 by augmentation of T cell apoptosis

We have recently reported the accumulation of oligoclonal activated T cells in the spontaneously developed autoimmune pancreatitis in aly/aly mouse. In this study, we examined the effects of FK506 in this mouse model in preventing autoimmune pancreatitis and investigated its action on calcium signalling apoptosis of alymphoplasia (aly) lymphocytes in vitro. Mice were treated with FK506 from 8 to 25 weeks of age. At the age of 15 weeks, minimal mononuclear cell infiltration was observed in the pancreas in both the FK506 treated group and the control group. Furthermore, a marked cell infiltration associated with destruction of acini and partial fatty changes were observed in 25-week-old control mice. In contrast, FK506 treated mice showed almost no tissue destruction or mononuclear cell infiltration at the age of 25 weeks. Furthermore, at 15 weeks of age, most mononuclear cells in FK506-treated mice were TUNEL positive, whereas only a few were positive in control mice. This augmentation of T cell apoptosis by FK506 was confirmed using naive splenocytes activated by PMA and ionomycin in vitro. Finally, a suppressive effect of FK506 on Bcl-2 production but not on Bax production was confirmed by Western blotting. This unique effect of FK506 on the augmentation of T cell apoptosis is probably one of the mechanisms explaining its beneficial effect on aly autoimmune pancreatitis.     

Heat and water vapour transfer of protective clothing systems in a cold environment,measured with a newly developed sweating thermal manikin

A moveable sweating thermal manikin has recently been developed. Thermal and water-vapour resistances of three kinds of cold-protective clothing ensembles, laminated with polytetrafluoroethylene, polyurethane and without a laminate were measured, with the aid of the manikin in a cold environment of 5°C with a relative humidity of 70% and an air velocity of around 1.5 m s^–1. Two sweating rates of 65 and 130 g m^–2 h^–1 were employed. Supplied heat fluxes in both of the sweat rates ranged from 350 W m^–2 to 400 W m^–2. To maintain a comfortable condition, the skin wettedness (w) (mean weighted value) had to be kept at 0.6. The measurements obtained from the manikin when testing the three ensembles were w=0.3 (approximately) for the low sweat rate and w0.6 for the high sweat rate, irrespective of the property differences among the ensembles. In addition, the condensation in the ensembles in comparison with those calculated from an analytical equation is discussed. Condensation mass fluxes in the ensembles obtained byexperiment and those from the calculation agreed sufficiently well. Thus, distribution of the condensation in the ensembles was estimated using the equation.     

Analgesic action of loperamide,an opioid agonist,and its blocking action on voltage-dependent Ca2+ channels

We investigated the relationship between the antinociceptive effect of the opiate agonist loperamide at the spinal level and its inhibitory effect on calcium influx. Intrathecal administration of loperamide showed a significant antinociceptive effect in the formalin test, which was not prevented by naloxone. On the other hand, no significant effects were observed by nicardipine, an L-type specific blocker, or by BAY K8644, an L-type specific agonist, suggesting no significant role of L-type calcium channels in nociceptive signal transduction. Loperamide suppressed the calcium influx in dorsal root ganglion neurons. As the antinociceptive effect of loperamide was not affected by naloxone or other calcium channel blocking toxins, and loperamide showed a direct inhibitory effect on calcium-influx, the analgesic effect of intrathecally injected loperamide might be due to its blockade of the voltage-dependent calcium channels at the terminals of the primary afferent fibers.