The role of taurine in neuronal protection following transient global forebrain ischemia.

Osmoregulation and post ischemic glutamate surge suppression (PIGSS) are important mechanisms in the neuroprotective properties of taurine. We studied the role of taurine in PIGSS following transient global forebrain ischemia (TGFI). A group of gerbils received a high dose of continuous intracerebral taurine during the peri-ischemic period. Beta-alanine was given similarly to a negative control group. The control group consisted of animals undergoing only TGFI. On the fourth day following commencement of drug administration, TGFI was induced. Concurrently, half the animals from each group receiving an agent had intracerebral microdialysis. All animals underwent histological assessment at day 7. The microdialysis and histological data was analyzed. Our results showed that taurine treatment did not cause PIGSS. The histological difference between the three groups was statistically insignificant. We conclude that intracerebral taurine in the dosage administered during peri-ischemic period, does not result in PIGSS or histologically evident neuroprotection.

Simultaneous identification of static and dynamic vagosympathetic interactions in regulating heart rate.

We earlier reported that stimulation of either one of the sympathetic and vagal nerves augments the dynamic heart rate (HR) response to concurrent stimulation of its counterpart. We explained this phenomenon by assuming a sigmoidal static relationship between nerve activity and HR. To confirm this assumption, we stimulated the sympathetic and/or vagal nerve in anesthetized rabbits using large-amplitude Gaussian white noise and determined the static and dynamic characteristics of HR regulation by a neural network analysis. The static characteristics approximated a sigmoidal relationship between the linearly predicted and the measured HRs (response range: 212.4 +/- 46.3 beats/min, minimum HR: 96.0 +/- 28.4 beats/min, midpoint of operation: 196.7 +/- 31.3 beats/min, maximum slope: 1.65 +/- 0.51). The maximum step responses determined from the dynamic characteristics were 7.9 +/- 2.9 and -14.0 +/- 4.9 beats. min-1. Hz-1 for the sympathetic and the vagal system, respectively. Because of these characteristics, changes in sympathetic or vagal tone alone can alter the dynamic HR response to stimulation of the other nerve.

Cholinesterase affects dynamic transduction properties from vagal stimulation to heart rate.

Recent investigations in our laboratory using a Gaussian white noise technique showed that the transfer function representing the dynamic properties of transduction from vagus nerve activity to heart rate had characteristics of a first-order low-pass filter. However, the physiological determinants of those characteristics remain to be elucidated. In this study, we stimulated the vagus nerve according to a Gaussian white noise pattern to estimate the transfer function from vagal stimulation to the heart rate response in anesthetized rabbits and examined how changes in acetylcholine kinetics affected the transfer function. We found that although increases in the mean frequency of vagal stimulation from 5 to 10 Hz did not change the characteristics of the transfer function, administration of neostigmine (30 microg . kg-1 . h-1 iv), a cholinesterase inhibitor, increased the dynamic gain from 8.19 +/- 3.66 to 11.7 +/- 4.88 beats . min-1 . Hz-1 (P < 0.05), decreased the corner frequency from 0.12 +/- 0.05 to 0.04 +/- 0.01 Hz (P < 0.01), and increased the lag time from 0.17 +/- 0.12 to 0.27 +/- 0.08 s (P < 0.05). These results suggest that the rate of acetylcholine degradation at the neuroeffector junction, rather than the amount of available acetylcholine, plays a key role in determining the dynamic properties of transduction from vagus nerve activity to heart rate.

Attenuated glutamate release during ischemia in ethanol-administered gerbils.

Previous studies have found an association between prior ethanol consumption and aggravated stroke outcome. Gerbils were intermittently given ethanol injections (s.c.) for 21 days at doses of 1 and 4 g/kg. After cessation of injections and appropriate weight gain, subjects underwent bilateral carotid occlusion while amino acid neurotransmitter levels in the hippocampus were monitored. Both the low and high dose ethanol groups demonstrated significantly decreased glutamate release compared with saline-treated controls during ischemia (p < 0.05). These results are consistent with a long-lasting ethanol-induced decrease in synaptic density in the hippocampus. That no intergroup differences on histological or neurobehavioral measures was found may suggest a functional dissociation of glutaminergic involvement in the pathogenesis of aggravated stroke outcome with alcoholism.

Isolation, structural determination and expression of a novel reg gene, human regI beta.

We have isolated a novel human gene and cDNA encoding a member of the regI proteins, regI beta. The gene encodes a 166-amino acid protein which has 22 amino acid substitutions in comparison with the previously isolated human reg protein, regI alpha. RegI beta was expressed only in pancreas, whereas regI alpha was expressed in kidney and stomach as well as in pancreas.

Origin and disposal of 1,5-anhydroglucitol, a major polyol in the human body.

The origin and disposal of 1,5-anhydro-D-glucitol (AG), one of the main polyols found in the human body, was studied in normal subjects and diabetic patients. AG was detected in various kinds of foods. The mean AG supplement through foods was estimated to be approximately 4.38 mg/day, which was compatible with that calculated in a food analysis (average 0.22 mg AG/100 kcal in Japanese foods) on eight healthy subjects. The mean AG excretion in urine was approximately 4.76 mg/day in these subjects. Excretion into stools was negligible. From observations on the patients without oral supplement of AG, 0.4 mg of daily de novo synthesis of AG was strongly suggested. It was also implied that urinary AG excretion occurred soon after food ingestion and that its amount was closely correlated with daily supplement through foods. Thus the fundamental kinetics of AG were recognized as follows: 1) AG in the body originates mainly from foods and is well absorbed in the intestine, 2) AG is little degraded and metabolized in the body, and 3) an equilibrium exists between oral supplement plus a small but steady amount of de novo synthesis and excretion in urine.

Antibiotic production by the marine photosynthetic bacterium Chromatium purpuratum NKPB 031704: localization of activity to the chromatophores.

Over 200 strains of marine purple photosynthetic bacteria were isolated. Two strains showed antibiotic activity towards Saccharomyces cerevisiae and were tentatively identified as Chromatium purpuratum. Crude antibiotic, prepared by solvent extraction, showed a broad antimicrobial spectrum. The highest activity was found in the chromatophore fraction. Chromatographic separation of purified light harvesting complex from one strain, NKPB 031704, showed the presence of two separate pigmented compounds which were responsible for antimicrobial activity. Our findings reveal the unexpected ability of photosynthetic bacteria to produce broad spectrum antibiotics. In addition, this is the first example of intracellular localization of antibiotic activity in a marine bacterium.

Cross reactive identification of types 1 and 2C fibers in human skeletal muscles with monoclonal anti-neurofilament (200 kd) antibody.

Types 1 and 2C fibers in human skeletal muscle were cross-reactively identified with monoclonal anti-bovine neurofilament (200 kd) antibody. Thirty seven biopsy samples including sixteen vastus lateralis muscles, twelve lumbar paravertebral muscles, six gluteus medius muscles, two flexor carpi ulnaris muscles, and one flexor pollicis longus muscle, were examined. Serial transverse sections were stained histochemically with myofibrillar ATPase (pH 10.4, 4.6, 4.3) and DPNH-tetrazolium reductase reactions, and immunochemically using the avidin-biotin-peroxidase complex with the primary antibodies of monoclonal anti-bovine neurofilament (200 kd, 160 kd, 70 kd) antibodies and anti-bovine glial filament acidic protein antibody. The immunochemical reaction with anti-NF (200 kd) antibody could distinguish two kinds of fibers; positive and negative in all of the specimens. No fiber was recognized with other antibodies. Myosin ATPase reactions in serial sections proved that the positively stained fibers with anti-NF (200 kd) antibody were types 1 and 2C fibers and negative fibers types 2A and 2B fibers. At present, it is not known what substance is responsible for the cross-reaction with the monoclonal anti-NF (200 kd) antibody in types 1 and 2C fibers, but this unique antibody would be valuable in two aspects: one concerns the problem of the evolution of fiber types, and the other the utility as another supplemental method to conventional myosin ATPase scheme.