Effects of daily administration of methamphetamine on multiple active/passive avoidance performance in rats

The effects of daily methamphetamine (M-Amp) treatment with (2 mg/kg/day, i.p.) were examined on multiple active/passive avoidance performance (MAP) in rats. After avoidance training, the animals were given M-Amp every day; on the days of learning sessions, which were on alternate days, the drug was administered at 15 min before the session. Daily administration of M-Amp produced enhancement of the number of respondings (running) as an excitatory dimension of behavior, disruption of immobilities as an inhibitory dimension, and impairment of successes as a discriminatory dimension, when compared with saline-treated rats. Following M-Amp withdrawal, recovery from these damages of learned behavior was observed, except the deterioration in the discriminative dimension. In conclusion, the MAP paradigm is good for assessing the behavioral effects of M-Amp treatment, making it easy to distinct the behavioral effects of M-Amp into excitatory-inhibitory and discriminative dimensions. It is important to distinguish the behavioral components induced by M-Amp, since the damage of learned avoidance performance consists of different dimensions in the M-Amp-treated rats. Impairment of discriminative behavior appears to demonstrate an attentional deficit, which may explain the behavioral disorderliness in M-Amp abusers who display no disturbance of apparent consciousness. These results are discussed with association of brain monoamine alterations.     

Structural design for nonmetallic optical fiber cables made of high-modulus and low linear-expansion coefficient polymer tubes

This paper describes a design method for a simple structure nonmetallic optical fiber cable, consisting of stranded loose tubes which are made from a high Young's modulus and low linear-expansion coefficient new polymer. First, the Young's modulus and stranding pitch of the tube unit to effectively bear all laying tension have become obvious from mechanical investigation. The allowable region between the pitch and optical fiber excess length also became obvious. In the allowable region, no additional loss due to tube characteristics was observed in the wide range ofpm 60degC. Moreover, it is shown that good performance of the cable using the new polymers is not attained using conventional cable materials.     

Preparation of lead magnesium niobate by a coprecipitation method

The ferroelectric complex perovskite lead magnesium niobate, Pb(Mg_1/3Nb_2/3)O₃ (PMN), was prepared by a coprecipitation method. As the niobium component, niobium oxalate was used. Among the various precipitants, tetramethylammonium hydroxide was effective for the formation of single-phase PMN without pyrochlore phase. The dielectric constant and the dissipation factor of PMN changed either the sintering temperature or the grain size. The maximum dielectric constant at the Curie point was obtained by sintering at 1220 °C in air for 2 h.     

Activation of protein-tyrosine kinase p72syk with concanavalin A in polymorphonuclear neutrophils

We studied the abundance, subcellular distribution of a non-receptor protein-tyrosine kinase p72syk (Taniguchi, T., Kobayashi, T., Kondo, J., Takahashi, K., Nakamura, H., Suzuki, J., Nagai, K., Yamada, T., Nakamura, S., and Yamamura, H. (1991) J. Biol. Chem. 266, 15790-15796) in porcine polymorphonuclear neutrophils and the activation upon the stimulation with concanavalin A. The abundance was about 0.1% of total proteins and mainly distributed in the particulate fraction. Upon concanavalin A stimulation, the activity of p72syk increased within 30 s, attained to the maximum level at 1 min, and then returned to the basal level within 6 min. This activation was observed in a dose-dependent manner and abrogated by simultaneous addition of methyl alpha-mannopyranoside. When both extra- and intracellular Ca2+ were depleted, the activation of p72syk was still persistent; in contrast, the deactivation process was completely abrogated even at 6 min after stimulation. The replenishment of Ca2+ in the presence of A23187 resulted in a similar deactivation pattern as seen in the Ca(2+)-rich condition. In addition, genistein and herbimycin A, potent protein-tyrosine-kinase inhibitors, were capable of reducing concanavalin A-evoked p72syk activation and Ca2+ mobilization as well as the aggregation and lysozyme release. Furthermore, A23187-induced Ca2+ accumulation in inhibitor-treated cells resulted in the restoration of those cellular responses. These lines of evidence suggest that p72syk is activated with concanavalin A in a Ca(2+)-independent manner, participating in a mechanism of Ca2+ recruitment, and negatively regulated by a feedback mechanism through Ca2+ in neutrophils.     

Patterns of jaw reflexes induced by incisal and molar pressure stimulation in relation to background levels of jaw-clenching force in humans

Patterns of jaw reflexes induced by periodontal stimulation were examined in ten adults. Surface electromyograms (EMGs) from the masseter and anterior temporal muscles were recorded when pressure stimulation was applied to either an incisor or a molar. Reflex responses to periodontal pressure stimulation varied, depending on the background levels of jaw-clenching force that preceded stimulation (background clenching force, BCF). At low BCF, excitatory reflexes were elicited from the jaw-closing muscles and jaw-clenching force. However, the magnitude of excitatory reflexes varied with the location of the stimulated tooth along the dentition. While excitatory reflexes were induced equally in the masseter and temporal muscles during incisal stimulation, stronger excitatory reflexes were induced in the temporal muscle than in the masseter muscle during molar stimulation. At high BCF, inhibitory reflexes in the jaw-closing muscles and jaw-clenching force were elicited in eight subjects (group A) during periodontal stimulation. However, excitatory reflexes in the muscles and force were elicited in the remaining two subjects (group B). In the subjects of group A, stronger inhibitory reflexes were elicited in the temporal muscle than in the masseter muscle, and jaw-clenching force also decreased during both incisal and molar stimulation. In the subjects of group B, the magnitude of excitatory reflexes decreased with increases in BCF.     

The relationship between stapling doughnuts: characteristics and functional results after total gastrectomy

BACKGROUND/AIMS: The objective of this study was to determine whether the thickness of the esophageal doughnut is related to postoperative results in total gastrectomy. METHODOLOGY: Thirty-eight total gastrectomy patients were studied, including 18 who underwent jejunal pouch reconstruction and 20 who did not have pouch reconstruction. We used the Proximate-ILS circular stapler, with purse-string suturing at the cut end of the esophagus performing only the mucosal layer manually in all cases. We divided the esophageal doughnuts after stapling into two groups: Group A: doughnut involving muscle tissue of 0-25% of the esophageal circumference; Group B: doughnut involved muscle tissue of 25-100% of the esophageal circumference. Reflux scores and the scintigraphic reflux index were determined. RESULTS: No significant difference was found between the two groups in reflux score or scintigraphic reflux index. CONCLUSIONS: These findings indicate that the degree of postoperative reflux esophagitis was not affected by the amount of the muscular layer included in the esophageal doughnut. Continuity, and not variability of the degree of involved muscle in the esophageal doughnut, is an important factor at the time of stapling.     

Production mechanism of polytitanocarbosilane and its conversion of the polymer into inorganic materials

The reaction of polycarbosilane with tetra-alkyltitanate proceeded at 300° C in nitrogen atmosphere by the condensation of Si-H bonds in polycarbosilane and the substituent groups of the tetra-alkyltitanate accompanied by evolution of alkan gas, and then the formation of Si-O-Ti bonds occurred. In this condensation reaction using tetra-isopropyl titanate, tetra-n-butyl titanate and tetra-2-ethylhexyl titanate, activation energies of the initial rate of the increase in molecular weight were 17.04, 20.07 and 31.07 kcal mol^–1 respectively, and thus the more bulky the substituent group of tetra-alkyltitanate, the lower the reactivity became. Of these alkyltitanates, tetra-2-ethylhexyl titanate was found to be the most advantageous reactant for obtaining polytitanocarbosilane with a narrow molecular weight distribution, low gel fraction and high titanium concentration. Polytitanocarbosilane with high titanium concentration was converted into the densified amorphous inorganic material with high Si-C bonding energy in high yield. Titanium contained in the pyrolysed polytitanocarbosilane was furthermore found to have the effect of inhibiting crystalline grain growth of -type SiC up to high temperature.     

Allelopathy of oats. I. Assessment of allelopathic potential of extract of oat shoots and identification of an allelochemical

The allelopathic potential of oat (Avena sativa L.) extracts was investigated under laboratory conditions. The ethyl ether-, acetone-, and water-soluble fractions obtained from the extract of oat shoots inhibited the germination and growth of roots and hypocotyls of lettuce (Lactuca sativa L.). The inhibitory activity of the water-soluble fraction was maximum, followed by that of ethyl ether-soluble and acetone-soluble fraction. An active principle of the water-soluble fraction was isolated and its structure was determined by spectral data asl-tryptophan.l-Tryptophan inhibited the growth of hypocotyls and roots of lettuce seedlings at concentrations greater than 0.03 and 0.1 mM, respectively. These results suggested thatl-tryptophan may be an allelochemical which affects the growth or germination of different plant species.     

Influence of Oxygen Ion Conduction on Nitric Oxide Decomposition

Ba₂In₂O₅, Ba₂Y₄O₉, and BaLa₂O₄ having brownmillerite-related structures were synthesized. Ionic conductivity and catalytic activity following the reduction of NO to N₂ were also investigated, both of which increased at the order-disorder transition temperature for oxygen vacancies of these compounds. It was made clear that the catalytic activity of NO decomposition reaction increased with a decrease in the order–disorder transition temperature. Moreover, it was found that ionic conductivity contributed to the catalytic activity of NO reduction to N₂.