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Biomedical subjects

A Watanabe

Publications and source records attributed to A Watanabe.

At least 1,081 records · Page 60Linked to original sources
PubMed1977

Increased alpha-fetoprotein biosynthesis in rats following DL-ethionine and carbon tetrachloride injuries.

The incorporation of 14C-leucine into alpha-fetoprotein (AFP) in serum and liver extracts from DL-ethionine and carbon tetrachloride (CCl4)-injured rats was measured directly by using an immunochemical technique. The maximum value with nearly 10-fold increases of serum AFP was obtained in 3 days of both treatments. However, no significant increase in the immunoprecipitable AFP in liver extracts was detected under these conditions.

Animals↗
PubMed1977

Catabolism of alpha-fetoprotein in carbon tetrachloride-injured rats.

The rate of alpha-fetoprotein (AFP) catabolism in carbon tetrachloride (CCl4)-treated rats was estimated to be essentially the same as that found in control adult and young rats. The blockade of the reticuloendothelial system by carbon particle resulted in slightly shorter t1/2 values of AFP. The amount of AFP synthesized pet day in CCl4-treated rats was theoretically calculated to be nearly 10-fold increase over that in control rats. Thus, the elevation of serum AFP concentrations in CCl4-treated rats is derived from the increased synthesis of AFP by injured liver.

Animals↗
PubMed1976

Gas-liquid chromatographic determination of sulphonamides.

Simultaneous qualitative analysis of fourteen sulpha drugs and their individual quantitative determinations have been performed by gas-liquid chromatography on solutions of dimethylformamide dialkylacetal derivatives of the drugs in acetone. Linear calibration curves were obtained for each sulpha drug under appropriate conditions. The structures of the above derivatives are assumed to be N1-methyl, N4-acetal sulphonamides, which can be detected with an electron capture detector with highly sensitive response. Columns used were 10% OV-101, 5% XE-60 and 5% OV-225.

Acetals↗
PubMed1976

Alteration of birefringence signals from squid giant axons by intracellular perfusion with protease solution.

The optical signal, arising from a transient birefringence change associated with excitation, was recorded from a squid giant axon together with the membrane potential change, and the effect of removal of the axoplasm on the optical signal was examined. In an unperfused axon, repetitive stimulation at a frequency of about 100 Hz produced two kinds of optical response. The initial response had a brief, spike-like time course and was elicited by each stimulating pulse. The delayed response had a slow time course and the sign of decreased light intensity, and summated with repetitive stimulation. Most of the axoplasm was removed from interior of the axon by intracellular perfusion with solutions containing pronase at a concentration of 0.1 mg/ml. The delayed response could selectively be eliminated by perfusion with a pronase-containing solution for 2-8 min. The result was interpreted as showing that the delayed birefringence signal originates from axoplasm when its gel structure was transiently disturbed by an increased Ca2+ influx associated with excitation. When perfusion was further continued the duration of the action potential started increasing and often a prominent after-depolarization appeared. At this stage the initial optical response was again followed by a large slow signal with the sign of increased light intensity. This reversed delayed response was tentatively assumed to originate from the membrane with some remaining axoplasm, but its cause is still not understood.

Animals↗
PubMed1976

Prompt elevation of rat serum alpha-fetoprotein by acute liver injury following a single injection of ethionine.

The mechanism of increased alpha-fetoprotein (AFP) production following a single injection of ethionine was investigated by using rats aged 5 weeks at the time of killing. Marked elevations of serum AFP concentrations occurred within 4 days in both male and female rats after administration of DL-ethionine or L-ethionine, although the increased levels of serum AFP and liver triglyceride in the adults were less marked in the male than in the female. No apparent necrosis of liver cells was observed in ethionine-treated rats. Frequent administrations of adenosine triphosphate after a single dose of ethionine prevented the increases in liver triglyceride and serum AFP levels. The increased concentrations of serum AFP, reaching a maximum level within 4 days, occurred before a slight increase in incorporation of 3H-thymidine into liver DNA. The serum AFP from ethionine-treated rats was immunologically and electrophoretically indistinguishable from that of fetal, carbontetrachloride-treated or hepatoma-bearing rats. These observations suggest that the increased production of AFP in ethionine-treated rats is closely associated with hepatic injury and is not the consequence of liver cell regeneration.

Adenosine Triphosphate↗
PubMed1976

A long-lasting birefringence change recorded from a tetanically stimulated squid giant axon.

A long-lasting birefringence change (the delayed response) was found to be produced in a tetanically stimulated squid giant axon. The change was independent of the concurrent membrane potential change, summated on repetitive stimulation, and always had a sign representing a decrease in resting birefringence. The axons was placed between a polarizer and an analyzer with their polarizing axes crossed, making an angle of 45 degrees with the longitudinal direction of the axon. The light beam that passed through the axon and the other optical elements was received by a photodiode. The change in light intensity evoked by repetitive stimulation was composed of brief initial responses, which took place in response to individual stimuli, and a delayed response, which developed gradually and lasted for several hundred msec. It was necessary to differentiate the effect of birefringence change from that of turbidity change. Formulas were derived on the assumption that the optical properties of the axon could be represented by a model of a uniaxial crystal that was not only birefringent but also dichroic, its extinction coefficients and the angle of retardation being changed independently on excitation. Calculations with them yielded the resting retardation, which agreed well with those obtained by the Senarmont's method, and the change in birefringence, which agreed well with the other calculated value derived from experiments using a quarter-wave plate. The results of the calculation confirmed the existence of the long-lasting birefringence change in the tetanically stimulated axon.

Action Potentials↗
PubMed1976

Induction of deoxyribonucleic Acid synthesis in potato tuber slices: role of protein synthesis.

Timing of protein synthesis which is a prerequisite to DNA synthesis induced in potato tuber tissue (Solanum tuberosum L.) by cut injury has been studied using cycloheximide. The induction of DNA synthesis which was measured by incorporation of (3)H-thymidine was completely inhibited when the inhibitor was applied to the tuber discs immediately after slicing. When the application of cycloheximide was delayed for 6 hours or more after slicing, DNA synthesis was observed but its rate was reduced to 20% of control. The inhibitory effect of cycloheximide, however, rapidly decreased when the inhibitor was applied at 6 or less hours immediately prior to determination of DNA synthesis. The effect of cycloheximide on the incorporation of (14)C-leucine suggests that the change in the effect of cycloheximide on the induction of DNA synthesis is not due to incomplete inhibition of protein synthesis. Cycloheximide did not have significant effects on either uptake or phosphorylation of (3)H-thymidine in the discs. Inhibition of both protein and DNA synthesis by cycloheximide was reversed by washing and further incubation of the discs. Almost no qualitative difference was detected by buoyant density analysis between DNA formed under inhibition of protein synthesis of the later stage and DNA synthesized under normal conditions. These results suggest that DNA synthesis induced in potato tuber tissue by cut injury requires continuous synthesis of new protein molecules in a characteristically programmed sequence.

Journal Article↗
PubMed1976

Chemical and genetic characterization of a monoclonal IgA(lambda) protein with both cryo- and pyro-precipitability.

Studies of a monoclonal IgA (lambda) protein with both cryo- and pyro-precipitability show that it belongs to the IgA2 subclass and is positive for the A2m(2) allotypic marker. Like other cryoglobulins, this protein also has an unblocked light chain, and its heavy chain belongs to the VHI subgroup. The first 22 N-terminal amino acids of the lambda chain of this protein showed less than 65% homology with those of other human lambda chains but showed 86% identity with that of an amyloid fibril protein reported by others. The alpha chain of this protein appears to have more glutamic acid or glutamine, or both, and less isoleucine residues than other human alpha chains.

Amino Acid Sequence↗
PubMed1976

Undifferentiated patterns of key carbohydrate-metabolizing enzymes in injured livers. I. Acute carbon-tetrachloride intoxication of rat.

In acute CCL4 intoxication of rats significantly increased activities of hepatic low-Km hexokinases, glucose-6-phosphate dehydrogenase, phosphofructokinase, aldolase A and pyruvate kinase M2 with concurrently decreased activities of glucokinase, glucose-6-phosphatase, fructose-1,6-diphosphatase, aldolase B and pyruvate kinase L were observed. The resulting enzyme pattern was apparently different from that in dietary induction. Principal component analysis revealed that the degree of enzyme deviation in the injured liver was much greater than that in the regenerating liver after partial hepatectomy and was closer to that in fetal liver or hepatoma tissue.

Adenosine Monophosphate↗
PubMed1976

Differential effects of glucagon on induction of rat liver glucose-6-phosphate dehydrogenase by liver injury and dietary change.

Glucagon effectively prevented the increase in glucose-6-phosphate dehodrogenase activity of rat liver following the administration of a glucose-casein mixture without altering the amount of the diet consumed. However, the increase of the enzyme level in carbon tetrachloride-injured rat liver was virtually insensitive to glucagon. The results obtained gave further evidence for the difference between these two induction mechanisms of glucose-6-phosphate dehydrogenase.

Animals↗
PubMed1976

Prevention of dietary induction of rat liver glucose-6-phosphate dehydrogenase by cyclic adenosine 3'.5'-monophosphate and its elimination by glucose prefeeding.

Glucagon, epinephrine and cyclic adenosine 3',5'-monophosphate (cyclic AMP) prevented the induction of liver glucose-6-phosphate dehydrogenase (G6PD) by refeeding a glucose-casein mixture to starved rats. The prevention by these agents occurred without any change in the amount of diet consumed. When the injection of cyclic AMP and the refeeding of glucose-casein diet were initiated simultaneously, there was an inhibiton of G6PD induction depending upon the dose and frequency of cyclic AMP administration during the period of refeeding, while when cyclic AMP was given later than 12 h of the refeeding, the lag period for induction of this enzyme, there was no preventive effect. A glucose prefeeding was also found to counteract the inhibitory effect of cyclic AMP on G6PD induction by the subsequent glucose-casein refeeding. The present data together with the elimination of actinomycin D effect by the glucose prefeeding suggest that the inhibitory effect of cyclic AMP on the induction of G6PD dehydrogenase is exerted at the level of transcription.

Animals↗