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Biomedical subjects

E Wada

Publications and source records attributed to E Wada.

At least 109 records · Page 6Linked to original sources
PubMed1988

Primary structure and expression of beta 2: a novel subunit of neuronal nicotinic acetylcholine receptors.

A new subunit, beta 2, of the neuronal nicotinic receptor family has been identified. This subunit has the structural features of a non-agonist-binding subunit. We provide evidence that beta 2 can substitute for the muscle beta 1 subunit to form a functional nicotinic receptor in Xenopus oocytes. Expression studies performed in oocytes have demonstrated that three different neuronal nicotinic acetylcholine receptors can be formed by the pairwise injection of beta 2 mRNA and each of the neuronal alpha subunit mRNAs. The beta 2 gene is expressed in PC12 cells and in areas of the central nervous system where the alpha 2, alpha 3, and alpha 4 genes are expressed. These results lead us to propose that the nervous system expresses diverse forms of neuronal nicotinic acetylcholine receptors by combining beta 2 subunits with different agonist-binding alpha subunits.

Acetylcholine↗
PubMed1986

r-Galactonolactone in experimental galactosemic animals.

An accumulation of galactose-1,4-lactone, an oxidation product of galactose, was observed in various tissues of galactosemic guinea pigs fed a 40% galactose diet for 6 weeks. In addition, an accumulation of the two galactose metabolites varied among organs. The highest content of the lactone was observed in the liver and the content of the lactone exceeded that of the reduced counterpart. The lens gave the highest galactitol content. In the serum the level of the lactone was very low. A trace amount of the lactone was detected in the kidney while it was mostly excreted into urine within 54 h upon withdrawal of the diet. On the other hand, in the animals kept on a high galactose diet for only 2 days, urinary lactone rapidly decreased. These observations indicated that a high galactose level in the circulation was associated with the production of the lactone in various tissues and that the accumulated lactone was released into the circulation very slowly and then excreted into the urine. Suppression of galactitol production by administration of an aldose reductase inhibitor resulted in the accumulation of the lactone in the lens, the testis, and the muscle, as well as in the circulation. The lactone thus produced was excreted exclusively into the urine. This observation indicates a close relationship between the oxidative and reductive metabolisms of galactose at a toxic level.

Aldehyde Reductase↗
PubMed1985

Combustion of organic samples by infrared furnace for carbon isotope analysis.

An apparatus for converting organic samples to carbon dioxide is described. It is especially designed to determine stable carbon isotope ratio of field samples. Unlike previous apparatus of similar configuration, a "Craig-line," it is free from the deposition of charred carbon on the line that results from an incomplete conversion. It includes an infrared furnace that heats both a CuO column and a sample tube. A removable, stainless-steel tube is present around the heated area, and this particular configuration makes it possible to begin every combustion procedure from room temperature, and consequently, to achieve a complete evacuation of air from the line even for heat-labile samples. The apparatus also includes a column that eliminates contaminating oxides such as nitrous oxide. The time necessary to process a sample is less than 30 min, and the precision of the carbon isotope measurement is comparable with that of "Craig-line." The coefficient of variation of carbon content determinations was no more than a few percents for most samples examined. An incidental finding was made that an isotopic fractionation of uric acid occurred during its preparation from penguin excreta by a high-performance liquid chromatography.

Antipyrine↗
PubMed1984

Finding of a galactose-oxidation-product in lens of galactose-fed guinea pig.

From studies on polyols in lens of galactose-fed guinea pigs, r-galactono-1,4-lactone was found, which proves the presence of galactonic acid as a product of galactose oxidation, by gas liquid chromatography and mass spectrometry. The content of this component was one tenth of that of galactitol. In vitro culture of rat lens in 30 mM galactose-loaded media demonstrated the formation of the lactone. The significance of the lactone was discussed with respect to the galactose metabolism in lens.

Animals↗
PubMed1984

Ageing and compositional changes of rat lens.

In order to elucidate chemical changes in the lenses of aged animals, carbohydrate and fatty acid compositions were studied in 36 healthy male and female Fischer 344 rats from 3 weeks to 32 months of age. Senile cataract was observed on six lenses of 12 rats aged 28-32 months. The carbohydrate content increased rapidly within 7 months of age and remained constant until 29 months. But the myoinositol content showed a maximum at 7 months of age and afterwards a decreasing trend was observed. In cataractous lenses, the myoinositol content decreased rapidly; sorbitol and fructose showed similar changes although the rates were much lower than that of myoinositol. Lens fatty acids increased steadily during the life span and the ratio of unsaturated to saturated fatty acids was maintained in a narrow range (1.20-1.30). However, the value was significantly altered in cataractous lenses. An age-dependent change was found with nervonic acid, which increased markedly from 1.8% of fatty acids at 3 weeks of age to 6.8% at 29 months. In cataractous lenses, the predominant changes noticed were a rapid decrease of arachidonic acid and a high content of nervonic acid.

Aging↗
PubMed1984

Nondisulfide polymerization of gamma- and beta-crystallins in the human lens.

The water-soluble 43,000-dalton fraction (WS43) of the human lens has been shown to be heterogeneous. It appears to contain, in addition to actin, components related to the crystallins. Immunoblot reactions indicate that this polypeptide fraction is composed of dimers containing beta- and gamma-crystallin components. It has been estimated that 10-30% of this fraction arises by dimerization of gamma-crystallin. A possible route for the formation of the 43,000-dalton fraction is suggested by the observation that photolysis of gamma-crystallin with light greater than 295 nm leads to polymer formation, including the 43,000-dalton fraction. The polymerization products react with anti-WS43. The results suggest that photochemical reactions may lead to the accumulation of polymers of some of the crystallins with aging of the human lens. Similar covalently linked polypeptides have previously been shown to be present in the high molecular weight aggregates associated with cataract formation.

Aging↗
PubMed1984

Effect of parathyroid hormone, cyclic AMP and Ca2+ on the phosphorylation of brush border membranes in rabbit kidney.

Renal cortical slices were incubated with parathyroid hormone or dibutyryl cAMP and the effects on phosphate uptake and phosphorylation of proteins in brush border membranes isolated from the treated slices were determined. Na+ gradient-dependent phosphate uptake was inhibited. Phosphorylation of proteins of Mr=170 K, 135 K, 105 K, 88 K, and 68 K was increased after incubation with the hormone or the cyclic nucleotide. Phosphorylation of membrane proteins was also examined in isolated relatively intact brush border membrane vesicles and in membrane vesicles disrupted with Triton X-100. With intact membrane vesicles, total phosphorylation of the membrane was not significantly altered by cAMP. However, phosphorylation of proteins of Mr=85 K and 48 K increased whereas phosphorylation of proteins of Mr=170 K, 78 K, and 56 K decreased, relative to that found with slices. With detergent-treated membranes, which presumably were made permeable to [gamma-32P]-ATP, a cAMP-induced increase in total phosphorylation was demonstrated. Phosphorylation of proteins of Mr=135 K, 78 K, 65 K, and 56 K was markedly enhanced. These findings suggest that proteins of Mr=135 K, 78 K, 65 K, and 56 K are localized on the cytosolic side of the membrane whereas proteins of Mr=85 K and 48 K are present on the luminal surface of the membrane. Incubation of the isolated brush border membrane vesicles with Ca2+, or Ca2+ plus cAMP, also affected the phosphorylation of membrane proteins. The phosphorylation of proteins of Mr=105 K, 68 K, and 20 K was increased by Ca2+. The Mr=20 K protein may be myosin light chain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Material cycling and organic evolution.

Intertwined cycles of matters are proposed to be one of the essential characteristics of life. The increase in the amount of recycled matters within biological groups and the complication of the cycling network are considered to be the early development of life soon after its appearance on the Earth. From this point of view, the origin of a cell alone can not sufficiently be regarded as the origin of life. The origin of a cell must be followed by a formation of material cycling among cells, if the cells are to stay on the Earth long enough so that they could be called life. This biogeochemical viewpoint leads to a quantitative analysis of life activity. A formula is presented to exemplify the potential utility of the viewpoint. It is applied to analyses of possible early developments of life and of an impact of present human activity on the global carbon cycle. Further application of the viewpoint to a variety of biogeochemical, sociogeochemical, ecological, and environmental problems should eventually show whether there is some utility in this view.

Animals↗
PubMed1982

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Computers↗
PubMed1981

Studies on lens proteins of mice with hereditary cataract. I. Comparative studies on the chemical and immunochemical properties of the soluble proteins of cataractous and normal mouse lenses.

Total soluble and insoluble proteins of the lens were similar in normal and hereditary cataractous mice up to 1 week of age. Thereafter, the normal mouse lens showed a continued increase in weight and protein content until 500 days of age. In cataractous mice, while the total protein content increased up to 60 days and reached a plateau, the soluble protein content declined dramatically from day 22 to day 60, and then the rate of decrease remained constant up to 500 days. At different ages, the soluble proteins were separated by gel filtration into the high molecular weight proteins, alpha-, beta- and gamma-crystallin fractions. All of these showed an age-related increase in the normal lens, and the relative values of alpha- and beta-crystallins increased for a 410-day period. On the other hand, in the cataractous process, the high molecular weight protein increased, and alpha-, beta- and gamma-crystallins decreased: the degree was especially marked in gamma-crystallin. Immunochemical studies indicated that the aggregation of beta-crystallin occurred much earlier in the cataractous lens than in the normal. Analysis of the amino acid composition and ultraviolet absorption spectra revealed no significant chemical differences between the crystallins of the normal and the cataractous lens.

Aging↗
PubMed1979

A defect of the myo-inositol maintenance mechanism in the lens of hereditary cataract mice.

The myo-inositol uptake system was studied in lenses of normal and hereditary cataract mouse. The normal mouse was able to accumulate myo-inositol continuously from medium and keep it in a high concentration. The specific myo-inositol uptake was dependent on temperature and it decreased in Ca(2+)-free medium. In contrast, specific uptake of myo-inositol reached a plateau after 15 min in the cataract mouse lens although initial incorporation was more rapid than that in normal mouse lens. This uptake system was not affected by temperature or Ca(2+) in the medium. The rate of myo-inositol efflux into the medium was more rapid in the cataract lens than that of the normal lens. It was shown that the low level of myo-inositol in the lens of hereditary cataract mouse was due to the defect of myo-inositol transport system and the enhanced efflux rate. These results suggest a dysfunction of the lens membrane.

Animals↗