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Biomedical subjects

T Tsuchiya

Publications and source records attributed to T Tsuchiya.

At least 811 records · Page 45Linked to original sources
PubMed1979

Extrusion of sodium ions energized by respiration and glycolysis in Escherichia coli.

Extrusion of sodium ion from cells of Escherichia coli was measured using an Na+ electrode. When oxygen was supplied to an anaerobic cell suspension, extrusion of Na+ was observed. The addition of glucose under anaerobic conditions also caused Na+ efflux. The extrusion of Na+ energized by respiration and glycolysis was completely inhibited by a proton conductor, carbonyl cyanide m-chlorophenylhydrazone. These observations are consistent with the view that Na+ transport occurs secondarily to H+ circulation. Interestgly, induction of the melibiose transport system, which is coupled to Na+, greatly enhanced Na+ transport activity.

Anaerobiosis↗
PubMed1979

The change in the load-sustaining ability and in the series elasticity in Mytilus smooth muscle during isotonic shortening.

1. The change in the ability to sustain a load and the change in the series elasticity in the anterior byssal retractor muscle (a.b.r.m.) of Mytilus edulis during isotonic shortening was studied by recording the length changes following step changes in load. 2. When a load of 0.7--0.9 P0 WAs applied after a period of isotonic shortening under a small load (0.05--0.1 P0), the muscle fibres showed continuous isotonic lengthening, indicating a reduction in the ability to sustain a load during isotonic shortening. 3. Following the application of a load of 0.3--0.6 P0 during isotonic shortening under a small load, the fibres exhibited a transient isotonic lengthening before starting to shorten isotonically, indicating some degree of restoration in the load-sustaining ability after the step increase in load. 4. No appreciable reduction in the load-sustaining ability was observed during isotonic shortening under a large load (more than 0.7 P0). 5. The load--extension curves of the series elasticity determined during isotonic shortening were found to be scaled down roughly in proportion to the isotonic load. 6. The stiffness of the muscle fibres during the isotonic shortening approached a certain finite value, when the isotonic load tended to zero. If the stiffness was measured during the development of isometric tension, the stiffness--isometric tension curve extrapolated towards the origin. 7. High-speed cinematography during the step change in load indicated a fairly uniform distribution of the series elasticity along the length of the preparation. 8. These results are discussed in relation to the sliding filament model of muscle contraction.

Animals↗
PubMed1978

Effect of lithium ion on melibiose transport in Escherichia coli.

Both Li+ and Na+ stimulated the uptake of thiomethylgalactoside by the melibiose transport system of Escherichia coli. On the other hand, Li+ inhibited the growht of cells on melibiose as a sole source of carbon. This inhibition was specific for melibiose, and Li+ had no effect on growth of cells on glucose, galactose, lactose, or glycerol. The effect of the cation on melibiose transport was investigated in a mutant which cannot utilize glucose. After entry into this cell, melibiose is cleaved into glucose and galactose by alpha-galactosidase, and the resulting glucose is excreted. Since the entry step was found to be rate-limiting, glucose production could be taken as a measure of melibose transport. Li+ inhibited the transport of melibiose, but not the induction of the melibiose operon nor the activity of alpha-galactosidase. Li+ was found to inhibit the entry of p-nitrophenyl-alpha-D-galactoside, but not p-nitrophenyl-beta-D-galactoside entry. Thus, the cation specificity for the melibiose membrane carrier varies different transport substrates.

Biological Transport, Active↗
PubMed1978

Effects of benzodiazepines and pentobarbitone on the gaba-ergic recurrent inhibition of hippocampal neurons.

The actions of benzodiazepines and pentobarbitone on GABA-mediated recurrent inhibition of hippocampal pyramidal neurons were investigated in the immobilized unanaesthetized cat. Extracellular action potentials of single neurons were recorded in regions CA1 or CA2 with 4 M NaCl-containing glass micropipettes. Bicuculline (0.1 mg/kg i.v.) reduced the period of inhibition induced by stimulation of the fimbria and the septum, but fludiazepam and diazepam (0.3--1.0 mg/kg i.v.) and pentobarbitone (15--30 mg/kg i.v.) prolonged the inhibition. The prolongation produced by these compounds was antagonized by the administration of bicuculline (0.3 mg/kg i.v.). The results suggest that these two classes of compounds potentiate GABA-mediated recurrent inhibition in hippocampal neurons in a similar way.

Action Potentials↗
PubMed1978

Calcium sensitivity of mantle muscle of squid.

Ca2+-sensitivity of squid muscle proteins was studied by competition tests between squid actin and carp myosin on squid myosin B and by cross combination tests between squid myosin and actin and between carp myosin and squid thin filament fraction. The results suggest that the regulatory system of the squid mantle muscle is actin-linked as in skeletal muscle rather than myosin-linked. This view is supported by the presence of troponin-like components on SDS-disc electrophoresis of squid thin filament fraction.

Actins↗
PubMed1978

Energy transduction in Escherichia coli: physiological and biochemical effects of mutation in the uncB locus.

The transduction of energy through biological membranes was investigated in Escherichia coli strains defective in the ATP synthetase complex. Everted vesicles prepared from strains containing an uncA or uncB mutation were compared with those of the parental strain for their ability to couple energy derived from the oxidation of substrates by the electron transport chain or from the hydrolysis of ATP by the Mg2+-adenosine triphosphatase, as measured by the energy-dependent quenching of quinacrine fluorescence or the active transport of 45Ca2+. Removal of the Mg2+-adenosine triphosphatase from membranes derived from the parental or an uncA strain caused a loss of energy-linked functions and a concomitant increase in the permeability of the membrane for protons. Proton impermeability was restored by treatment with N,N'-dicyclohexylcarbodiimide. When membranes of the uncB strain were treated in a similar manner, there was no loss of respiratory-driven functions, nor was there a change in proton permeability. These observations suggest that the uncB mutation specifically results in alteration of an intrinsic membrane protein channel necessary for the generation of utilzation of the electrochemical gradient of protons by that complex. Loss of the function of the proton channel is believed to prevent the transduction of energy through the ATP synthetase complex.

Adenosine Triphosphatases↗
PubMed1978

Role of Na+ and Li+ in thiomethylgalactoside transport by the melibiose transport system of Escherichia coli.

Thiomethyl-beta-galactoside (TMG) accumulation via the melibiose transport system was studied in lactose transport-negative strains of Escherichia coli. TMG uptake by either intact cells or membrane vesicles was markedly stimulated by Na+ or Li+ between pH 5.5 and 8. The Km for uptake of TMG was approximately 0.2 mM at an external Na+ concentration of 5 mM (pH 7). The alpha-galactosides, melibiose, methyl-alpha-galactoside, and o-nitrophenyl-alpha-galactoside had a high affinity for this system whereas lactose, maltose and glucose had none. Evidence is presented for Li+-TMG or Na+-TMG cotransport.

Biological Transport, Active↗
PubMed1978

Dipyridamole therapy in the nephrotic syndrome.

Dipyridamole was used in 30 cases of nephrotic syndrome, mostly of intractable type. The results indicate that the drug therapy proved to be effective in decreasing urinary protein and controlling nephrotic condition in 40% of the cases after an initial period of treatment. Long-term results of the drug on urinary protein and on nephrotic condition were rated as good in 36.7 and 53.3%, respectively, of the cases treated. The exact mechanism of action of dipyridamole in the nephrotic syndrome is still obscure in many respects. However, the fact that the drug shares its anti-platelet action with the non-steroid anti-inflammatory drugs, e.g. aspirin and indomethacin, and the rapidity with which it produces its urinary protein-decreasing effect, strongly suggests that it inhibits the release of vasoactive amines and other chemical mediators from blood platelets. As far as the present study is concerned, adverse side effects of dipyridamole were few or minimal, even when the drug used in large doses over a prolonged period of time. From these results it is considered that dipyridamole provides a new remedy which is worthy of trying in nephrotic syndrome as a means of reducing the requirement of steroids and immunosuppressive drugs.

Adolescent↗
PubMed1978

Cation-sugar cotransport in the melibiose transport system of Escherichia coli.

The entry of Na+ or H+ into cells of Escherichia coli via the melibiose transport system was stimulated by the addition of certain galactosides. The principal cell used in these studies (W3133) was a lactose transport negative strain of E. coli possessing an inducible melibiose transport system. Such cells were grown in the presence of melibiose, washed, and incubated in the presence of 25 microM Na+. The addition of thiomethylgalactoside (TMG) resulted in a fall in Na+ concentration in the incubation medium. No TMG-stimulated Na+ movement was observed in uninduced cells. In an alpha-galactosidase negative derivative of W3133 (RA11) a sugar-stimulated Na+ uptake was observed in melibiose-induced cells on the addition of melibiose, thiodigalactoside, methyl-alpha-galactoside, methyl-beta-galactoside, and galactose, but not lactose. It was inferred from these studies that the substrates of the melibiose system enter the cell on the melibiose carrier associated with the simultaneous entry of Na+ when this cation is present in the incubation medium. Extracellular pH was measured in unbuffered suspensions of induced cells in order to study proton movement across the membrane of cells exposed to different galactosides. In the absence of external Na+ or Li+ the addition of melibiose or methyl-alpha-galactoside resulted in marked alkalinization of the external medium (consistent with H+-sugar cotransport). On the other hand TMG, thiodigalactoside, and methyl-beta-galactoside gave no proton movement under these conditions. When Na+ was present, the addition of TMG or melibiose resulted in acidification of the medium. This observation is consistent with the view that the entry of Na+ with TMG or melibiose carries into the cell a positive charge (Na+) which provides the driving force for the diffusion of protons out of the cell. It is concluded that the melibiose carrier recognition of cations differs with different substrates.

Biological Transport↗