Sub-nanometre elemental analysis of Cu cluster in Fe-Cu-Ni alloy using aberration corrected STEM-EDS.

In order to understand the mechanism of Cu clustering and Ni effects on Cu clusters, a sub-nano scale structural and elemental analysis of Cu-bearing steels was carried out through an aberration corrected scanning transmission electron microscope. Based on systematic observation condition adjustment by changing the electron scattered angle, we adopted an inner scattered semi angle of between 50 and 70 mrad for the scanning transmission electron microscope energy dispersive X-ray spectroscopy analysis. Under this condition, Cu precipitates such as 9R are clearly recognized through atomic scale scanning transmission electron microscope annular dark field images. Cu clusters, before transforming to 9R, are detected on the dislocation and have a periodical strain field. Ni enrichment is also observed in the vicinity of Cu clusters. Considering these enrichment phenomena of Cu and Ni, it is found that Cu diffuses rapidly through dislocation, while at the same time, Ni enrichment occurs by ejection from Cu clusters and forms a shell structure.

Recrystallization phenomena in an IF steel observed by in situ EBSD experiments.

In situ electron backscatter diffraction microstructural analysis of recrystallizing interstitial free steels deformed to strains of 0.75 and 1.6 has been carried out in a FEG-SEM. The experimental procedures are discussed, and it is shown that there is no degradation of the electron backscatter diffraction patterns at temperatures up to 800 degrees C. Analysis of the surface and interior microstructures of annealed samples shows only minor difference, which suggests that in situ annealing experiments are of value. In addition, it is shown that in situ measurements allow a detailed comparison between the same areas before and after annealing, thereby providing information about the recrystallization mechanisms. Sequential recrystallization phenomena, such as initiation and growth of new grains, are observed at temperatures over 740 degrees C, and depending on the deformation histories, different recrystallization behaviour is observed. It is found that {111} <123> recrystallized grains are preferentially formed in the highly deformed material, whereas no strong recrystallization texture is formed in the lower strained material.

Fasudil (HA1077), an intracellular calcium antagonist, improves neurological deficits and tissue potassium loss in focal cerebral ischemia in gerbils.

The effects of an intracellular calcium antagonist fasudil (HA 1077) on protein synthesis, ion derangement, brain edema, and the neurological signs associated with focal cerebral ischemia, were investigated via a nine-hour occlusion of the left common carotid artery (CCA) in Mongolian gerbils. Protein synthesis was evaluated by the amount of incorporation of [14C]methionine into the tissue. Intravenous infusion of fasudil hydrochloride (1 mg kg-1) just after CCA ligation was effective in reducing neurological deficits six and nine hours after CCA ligation, as well as loss of tissue potassium. However, fasudil did not ameliorate the brain edema or the accumulation of sodium in the tissue. On the other hand, fasudil improved the uptake of [14C]methionine, but not its incorporation into the tissue. The improved uptake of tracer into the tissue may indicate the facilitation of collateral blood flow by fasudil. These results suggest that fasudil may mitigate ischemic damage in the penumbral zone, possibly by ameliorating collateral blood flow and preventing calcium-related cell damage.

Does the anabolic metabolism of L-[2-18F]fluorophenylalanine and L-[2,6-3H]phenylalanine differ in the cerebrum and the cerebellum?

The anabolism of isotopically labeled amino acids was compared between the cerebrum and the cerebellum in conscious rat at three feeding conditions. After L-[2-18F]fluorophenylalanine and L-[2,6-3H]phenylalanine injections, the incorporation rate of both radioactivity into protein fraction showed no difference between the cerebrum and the cerebellum at normal condition, but the lipid fraction in the cerebellum was higher than that in the cerebrum in any conditions. These results show the usefulness of L-[2-18F]fluorophenylalanine as a positron emission tomography tracer and different anabolic rate of the amino acids to lipid between the cerebrum and cerebellum.

Quantitative distribution of rat brain monoamine oxidase A by [14C]clorgyline autoradiography.

The distribution of functionally active monoamine oxidase type A (MAO-A) was investigated by in vivo quantitative autoradiography using [14C]clorgyline in normal, conscious rat brain. [14C]clorgyline was synthesized by the methylation reaction of N-desmethylclorgyline using [14C]methyliodide. Sixty minutes after [14C]clorgyline administration (1.58 MBq/animal i.v.), the brains were removed and prepared for autoradiography by washing the brain sections with 5% trichloroacetic acid solution to remove the nonbinding free tracer. The amount of MAO-A was calculated from the regional acid-insoluble tissue radioactivity and the specific activity of the tracer. The highest amount of MAO-A (5.84 nmol/g tissue) was found in the locus coeruleus. The interpeduncular nucleus, habenular nucleus, fasciculus retroflexus, and solitary tract nucleus possessed over 1.6 nmol/g tissue of MAO-A. Among 23 regions of interest, the lowest amount of MAO-A (0.37 nmol/g tissue) was found in the globus pallidus. The findings of this study suggest that the pattern of MAO-A parallels both in neuroanatomical distribution and in density that of norepinephrine and serotonin innervation. The MAO-A concentration was, however, relatively low in the dopamine-related areas. This corresponded to the previous results obtained by histochemical analysis. In addition, among the white matter structures, a high amount of MAO-A was found specifically in the fasciculus retroflexus.

L-[2-18F]fluorophenylalanine and L-[U-14C]phenylalanine: a comparative study of their transport to rat brain.

The transport rates of L-[2-18F]fluorophenylalanine ([18F]Phe) and L-[U-14C]phenylalanine ([14C]Phe) across the blood-brain barrier were compared in saline, large neutral amino acids (NAA) and large basic amino acids (BAA) loaded rats. The fraction of transported tracer (FTT) was expressed as the ratio of brain radioactivity to integrated plasma radioactivity at 5 min after injection of the tracers. Cerebral FTTs of [18F]Phe and [14C]Phe in the control group were 0.042 and 0.045, respectively, and decreased to 0.016 and 0.019 in the NAA loaded group. The ratios of FTT of [18F]Phe and that of [14C]Phe were approx. 0.90, and did not differ among the three groups. These results indicate that the transport of [18F]Phe from the blood to the brain can be considered to be mediated by the NAA transport system and that its transport rate is almost the same as that of [14C]Phe.

A convenient method for regional monoamine oxidase-A determination by [14C]clorgyline autoradiography.

The availability of clorgyline for regional monoamine oxidase-A (MAO-A) determination was examined using [14C]clorgyline in rat. [14C]Clorgyline was synthesized by the methylation reaction of N-desmethyl-clorgyline and [14C]methyliodide in dimethylformamide with high radiochemical yield. The MAO-A distribution map by autoradiography correlated with that by histochemical technique and its quantity was consistent with the calculated MAO-A amount based on previous reports. The combination of labeled clorgyline and autoradiographic technique will promise the quantitative measurement of regional MAO-A distribution.

Effects of HA1077, an intracellular calcium antagonist, on neurotransmitter metabolism in rat brain in vivo.

The effect of HA1077, an intracellular calcium antagonist, on neurotransmitter metabolism in rat brain was investigated in vivo. After administration of HA1077, at doses of 0.1, 0.3, and 3 mg/kg, 5-hydroxyindoleacetic acid (5-HIAA) levels increased in most regions except midbrain. In the striatum, parallel increases of both serotonin (5-HT) and 5-HIAA levels were observed at 0.3 mg/kg, but only the 5-HT level increased at 0.1 mg/kg. These results suggest that HA1077 may activate the turnover or synthesis of 5-HT. After administration of HA1077 at 0.3, 1, and 3 mg/kg, the dopamine (DA) level was increased in the striatum, but 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid levels were unchanged. After HA1077 administration at 1 mg/kg, both DA and DOPAC levels increased in the hypothalamus and only DA level increased in the cerebral cortex. By contrast, DOPAC level decreased in the midbrain after HA1077 treatment at 0.1 and 0.3 mg/kg, and in the brainstem at 0.1 and 10 mg/kg. The ratio of [3H]-N-methylspiperone accumulation relative to that in the cerebellum did not change after HA1077 treatment at any of the doses employed. Thus, the effects of HA1077 on neurotransmitter metabolism are complex and vary depending on the dosage and sites of the brain. Although the dose-dependent effects of HA1077 on neurotransmitter metabolism are similar to those of calcium entry blockers, HA1077 can facilitate DA synthesis in the hypothalamus and striatum, unlike the calcium entry blockers.

Effect of thyrotropin-releasing hormone on cerebral blood flow in conscious rat.

The effect of thyrotropin-releasing hormone (TRH) was studied on local CBF (LCBF) in normal conscious rats. LCBF was measured by the autoradiographic [14C]iodoantipyrine method 5 min after TRH (5 mg/kg, i.v.) administration. TRH significantly increased LCBF in 22 of 33 brain regions. This increase of LCBF exceeded 100% of the control values in the cerebral cortices, whereas there was no significant increase in white matter or in some gray matter structures. The increase of CBF following TRH administration was abolished by pretreatment with indomethacin (5 mg/kg, i.v.). The mechanisms underlying the increase of CBF following TRH administration are discussed in relation to prostaglandin metabolism.

Effect of methotrexate on local cerebral blood flow in conscious rats.

The effect of methotrexate (MTX) on local cerebral blood flow (I-CBF) was studied with autoradiographic [14C]-iodoantipyrine methods in normal conscious rats. I-CBF was reduced by 30-57% in the rats given MTX (100 mg or 200 mg/body) as compared to that in the saline injected control group, but no dose-dependent effect was observed. The mechanism of I-CBF reduction by MTX was discussed.

[Effects of guanfacine on the levels of cyclic nucleotides in anesthetized rat brain regions].

Effects of an antihypertensive drug, guanfacine, on brain regional cyclic AMP and cyclic GMP levels were studied in anesthetized rats. Cyclic nucleotides were analyzed in seven brain regions. Guanfacine decreased blood pressure and heart rate 20 min after administration. Yohimbine inhibited these hemodynamic effects of guanfacine. Guanfacine reduced cyclic AMP levels in the hypothalamus. The reducing effect of guanfacine on cyclic AMP was antagonized by yohimbine in the hypothalamus. Guanfacine lowered cyclic GMP in the cerebellum, medulla oblongata and hypothalamus. Yohimbine inhibited the effect of guanfacine on cyclic GMP in the cerebellum, medulla oblongata and hypothalamus. Prazosin showed no effect on guanfacine induced change of cyclic nucleotides in any brain region. From these results, it is concluded that guanfacine decreased cyclic AMP and cyclic GMP in the hypothalamus. In addition, it is suggested that alpha-2 adrenoceptors mainly modulate these changes of cyclic nucleotides.

[Effects of clonidine on the levels of cyclic nucleotides in rat brain regions: the change in cyclic nucleotides after clonidine alone or in combination with alpha-antagonists].

The following 4 Wistar rat groups were sacrificed by microwave irradiation after measuring blood pressure and heart rate: 1) saline control (1 ml/kg, i.v.), 2) clonidine alone (50 micrograms/kg, i.v.). 3) prazosin pretreated (0.1 mg/kg, i.v.), 4) yohimbine pretreated (1 mg/kg, i.v.). Cyclic nucleotides were analyzed in seven brain regions. Clonidine decreased blood pressure and heart rate 20 min after administration. These effects of clonidine were inhibited by yohimbine. Clonidine increased the levels of cyclic AMP in the medulla oblongata (including pons) and hypothalamus. Prazosin attenuated the cyclic AMP-increasing action of clonidine in the cerebellum. Yohimbine inhibited this action of clonidine in the cerebellum, striatum and hippocampus. Clonidine reduced cyclic GMP levels in the hypothalamus and striatum. Prazosin potentiated the cyclic GMP-reducing action of clonidine in the medulla oblongata. Yohimbine attenuated this action of clonidine in the medulla oblongata and hypothalamus. From these results, it is concluded that clonidine changes the levels of cyclic nucleotides in brain regions, especially in the part of the autonomic nervous center. In addition, it is indicated that alpha 1- or alpha 2-adrenoceptor plays a different role in the regulation of brain cyclic nucleotides, region by region.

Evaluation of N-isopropyl-[125I]p-iodoamphetamine affinity sites in rat brain by autoradiography.

Affinity sites of N-isopropyl-[125I]p-iodoamphetamine (IMP) were studied in rat brain employing in vitro technique of receptor autoradiography. High degrees of IMP accumulation were observed in almost regions of white matter and some of gray matter. Phenethylamine, glutamic acid and serotonin suppressed IMP accumulation in all brain regions, in cerebral cortex and in hypothalamus, respectively. These results indicated that IMP was accumulated mainly due to its physicochemical property of lipophilicity and might have some interactions with neurotransmitter receptors.

Beta-adrenoceptor mediated inhibition of behavioral action of desipramine and of central noradrenergic activity in forced swimming rats.

The immobility-reducing action of desipramine (DMI) in forced swimming rats was attenuated by intracerebroventricular (i.c.v.) injection of isoproterenol (ISO) and potentiated by i.c.v. atenolol (ATE), a beta 1-adrenoceptor antagonist. The effect of ISO was blocked by ATE. When administered i.c.v. in normal rats, ISO reduced the contents of 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4), a major metabolite of noradrenaline, in the septal area, thalamus and hypothalamus while ATE had no effect in most of the brain regions. However, in forced swimming rats treated with DMI, ISO reduced MHPG-SO4 in 6 out of 8 brain regions tested and conversely, ATE increased the levels in the amygdala, septal area and hypothalamus. Similar to the behavioral effect, the effect of ISO was antagonized by ATE. These results support the hypothesis that central beta 1-adrenergic mechanisms inhibit the immobility-reducing action of DMI by reducing the activity of noradrenergic neurons in the brain.

Involvement of alpha- and beta 1-adrenergic mechanisms in the immobility-reducing action of desipramine in the forced swimming test.

The influences of various monoaminergic agents on the immobility-reducing action of desipramine (DMI) in the forced swimming test were examined. 5-Methoxy-N,N-dimethyltryptamine and methysergide, a serotonin agonist and antagonist, respectively, did not affect the duration of immobility. Pimozide, a dopamine antagonist, prolonged the duration of immobility at a dose of 0.5 mg/kg. However, at the doses tested, these drugs had no effect on the action of desipramine. Phenoxybenzamine, an alpha-adrenergic antagonist, prolonged the duration of immobility only with the largest dose (20 mg/kg), but the action of desipramine was completely blocked by this drugs at all doses. Intracerebroventricular injection of a beta-adrenergic agonist, isoproterenol (ISO), and two selective beta 1-adrenergic antagonists, atenolol (ATE) and practolol, dose-dependently diminished and potentiated, respectively, the action of desipramine although these drugs had no effect on the duration of immobility when given alone. A beta 2-adrenergic antagonist derived from oximino-9-fluorene, (IPS 339) did not influence the duration of immobility or affect the action of desipramine. The effect of isoproterenol was almost completely blocked by the pretreatment with atenolol and practolol but not by IPS 339. Subcutaneously-injected isoproterenol did not affect the action of desipramine. Isoproterenol and atenolol had no effect on the concentration of desipramine in brain regions. Phenylephrine, a postsynaptic alpha-adrenergic agonist, reduced the duration of immobility as did desipramine, but this action was not affected by isoproterenol and atenolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of nucleotides and nucleosides on the activity of cyclic AMP phosphodiesterase from rat brain.

Cyclic nucleotides phosphodiesterase (PDE) was prepared from cerebrum of male rats and its kinetic properties were studied. The phosphodiesterase preparation exhibited two Michaelis constants, 8.7 microM and 83.3 microM. Adenine derivatives such as adenosine, 5'-AMP and 2'(3')-AMP inhibited the PDE activity at concentrations exceeding 7 X 10(-3)M, and 2'-deoxyadenosine inhibited the activity at lower concentrations (Ki = 1.8 X 10(-3)M); its inhibiting efficacy was almost the same as that of theophylline (Ki = 1.9 X 10(-3)M). Guanine derivatives, on the other hand, showed several different effects. Guanosine and 3',5'-cyclic GMP activated the PDE at 10(-5) M and inhibited at concentrations higher than 10(-4)M. 2'(3')-GMP showed no effect, but 5'-GMP activated markedly at concentrations of 10(-3) to 10(-2)M. Thymidine showed slight inhibitory effect, but cytidine or 2'-deoxycytidine had no effect. Uracil derivatives such as uridine, 5'-UMP, 3',5'-cyclic UMP and 2'(3')-UMP activated the PDE at concentrations exceeding 3 X 10(-3) M. These results indicate that individual nucleosides and nucleotides exhibit structure-activity relationship with PDE.