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Biomedical subjects

C Kato

Publications and source records attributed to C Kato.

At least 145 records · Page 8Linked to original sources
PubMed1987

Mechanical properties and ATPase activity in glycerinated cardiac muscle of hyperthyroid rabbit.

Isometric tension, tension transients in response to rapid step stretches in length and ATPase activity were measured at constant levels of various Ca2+ activations in glycerinated right ventricular papillary muscle of L-thyroxine-treated (14 daily injections of 0.2 mg/kg) and control rabbits. The isometric tension increased sigmoidally as Ca2+ was varied from slightly below pCa 7 to about pCa 6 both in thyroxine-treated and control preparations. The maximum isometric tension in thyroxine-treated preparations, however, was only about 66% of that in control. The tension transients were characterized by clear three distinct phases; the first phase of an immediate tension increase coincident with the stretch, the second phase of a rapid quasi-exponential tension decrease and the third phase of a delayed quasi-exponential tension rise. In thyroxine-treated preparations, relative to controls, the time for 63% tension reduction in the second phase decreased from 39.3 +/- 2.8 ms (mean +/- SD, n = 5) to 20.2 +/- 2.0 ms (p less than 0.001) and the time for 63% tension rise in the third phase decreased from 483.9 +/- 14.3 ms to 298 +/- 15.9 ms (p less than 0.001). The ATPase activity increased in a sigmoid fashion with increasing Ca2+ from slightly above pCa 7 to slightly below pCa 6 both in thyroxine-treated and control preparations. However, the tension cost (ATPase activity/tension) was about two times greater in the thyroxine-treated preparations than in controls.

Adenosine Triphosphatases↗
PubMed1987

ATPase activity and tension development in mechanically-skinned feline jaw muscle.

At a muscle length L0 (just taut), isometric tension and ATPase activity were measured at constant levels of various Ca2+ activations in muscle fibres (2-3 mm long and 34-66 microns in diameter) isolated from temporal, masseter and digastric (anterior belly) muscles. The isometric tension increased in a sigmoid fashion with increasing Ca2+ concentration from about pCa 6.60 to pCa 5.00 in the temporalis and from about pCa 6.37 to pCa 5.00 in both the masseter and digastric. The maximum isometric tension from four preparations of each muscle averaged 44.4 +/- 6.6 g/mm2 in the temporalis, 31.9 +/- 4.0 g/mm2 in the masseter, and 23.9 +/- 5.5 g/mm2 in the digastric. The ATPase activity also increased sigmoidally with increasing Ca2+ concentration from slightly below pCa 7.0 to pCa 5.0 in the temporalis, and from slightly above pCa 6.0 to pCa 5.0 in both the masseter and digastric. The maximum ATPase activity obtained from four preparations of each muscle averaged 0.35 +/- 0.06 mumol/mg protein per min in the temporalis, 0.29 +/- 0.06 mumol/mg protein per min in the masseter, and 0.18 +/- 0.04 mumol/mg protein per min in the digastric. The tension cost (ATPase activity/tension) estimated from these results was lower in the digastric than in the temporalis or masseter, indicating more economical ATP consumption in the digastric.

Adenosine Triphosphatases↗
PubMed1987

Construction of an excretion vector and extracellular production of human growth hormone from Escherichia coli.

A new excretion vector, pEAP8, was constructed to develop an excretion system for Escherichia coli. This plasmid, derived from pEAP37, carried the weakly activated kil gene of plasmid pMB9 [Kobayashi et al., J. Bacteriol. 166 (1986) 728-732] and the penicillinase promoter and signal region of an alkalophilic Bacillus sp. to excrete foreign gene products. A gene for human growth hormone (hGH) was joined to this signal sequence through the HindIII site. The recombinant plasmid p8hGH1 thus constructed, was introduced into E. coli. The hybrid protein which was produced in E. coli carrying p8hGH1 was processed during transport through the inner membrane, with the mature hGH being excreted into the medium through the outer membrane which was made permeable by the action of the kil gene. The N-terminal amino acid sequence and the biological activity of the extracellular hGH were consistent with those of the authentic hGH.

Animals↗
PubMed1987

Improvements in self-concept after treatment of nocturnal enuresis: randomized controlled trial.

To determine whether changes in attitude and behavior occur after treatment of nocturnal enuresis, we randomly assigned 121 children aged 8 to 14 years to receive conditioning therapy (n = 66) or a 3-month waiting period (n = 55). All children completed the Piers-Harris Self-Concept Scale (P-H), the State-Trait Anxiety Scale (STAIC), and the Nowicki-Strickland Locus of Control test (NSLC) at entry and after treatment or delay. Parents completed the Achenbach Child Behavior Checklist (CBCL). There were no significant group differences in background demographic variables. Significant improvements in the P-H Scale (P = 0.04) and three of its subscales occurred in children in the treatment group compared with those in whom treatment was delayed. The changes were greatest for those who had the largest decreases in wetting frequency. Changes in CBCL, STAIC, and NSLC scores were not statistically significant. We conclude that there may be mental health benefits in children helped to master the symptom of enuresis, which in this age group is probably a chronic stressor.

Adolescent↗
PubMed1986

Length-tension relation of cat heart muscle studied by a segment-control method.

We studied the effects of the damaged ends on the length-tension relationship of the cat right ventricular papillary muscle during twitch contraction (30/min) using a newly developed segment-control system. The segment length (SL), defined as the distance between two thin black films attached to the central surface of the muscle with silicone grease, was measured by a Hamamatsu Photonics Width Analyzer (C1170) and Camera (C1000) and controlled with a servoactuator. The marker distance was determined to be either the central 24%-30% (short marker distance) or 47%-56% (long marker distance) of the muscle length (ML) at which the maximum developed twitch tension was observed (MLmax). The muscle was lengthened and shortened in a triangular fashion under both ML and SL isometric twitch modes over a period of 250s. The relationship between ML or SL and developed tension (DT, total minus resting tension) was obtained from the twitch tension data during the lengthening. The DT in the SL isometric twitch was always greater than that in the ML isometric twitch over the range of lengths studied. The slope of the SL-DT relation curve was much less steep than that of the ascending limb of the ML-DT relation curve. The gradient of the SL-DT relationship curve was greater for the long marker than for the short marker distance. The percentage shortening of SL in the ML isometric twitch increased with decreasing ML; it was greater for the short marker than for the long marker distance, particularly at shorter MLs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Excretion of the penicillinase of an alkalophilic Bacillus sp. through the Escherichia coli outer membrane is caused by insertional activation of the kil gene in plasmid pMB9.

Most of the cloned penicillinase from alkalophilic Bacillus sp. strain 170 and alkaline phosphatase were released into the culture medium by Escherichia coli strains bearing plasmid pEAP1 or pEAP2 (T. Kudo, C. Kato, and K. Horikoshi, J. Bacteriol. 156:949-951, 1983). We analyzed the basis for excretion of periplasmic enzymes in the cells bearing these plasmids. Several experiments such as subcloning, insertion of a chloramphenicol acetyltransferase cartridge, and DNA sequencing were done. A dormant kil gene in plasmid pMB9 was expressed by a promoter of the inserted DNA fragment of alkalophilic Bacillus sp. strain 170, and as a result, the outer membrane of E. coli became permeable, allowing the proteins to be excreted without cell lysis.

Amino Acid Sequence↗
PubMed1985

Ca2+ sensitivities and transient tension responses to step-length stretches in feline mechanically-stripped single-fibre jaw-muscle preparations.

At a muscle length, Lo (just taut), isometric tension at constant levels of various Ca2+ activations and transient tension responses to rapid length stretches (less than 1 per cent of Lo within 2 ms) at maximal Ca2+ activation level were measured in temporal, masseter and digastric (anterior belly) muscles (2-3 mm long and 24-48 micron in diameter). Steady isometric tension increased in a sigmoid fashion with increasing Ca2+ concentration from about pCa 7.28 to 4.49 in temporalis, from about pCa 6.18 to 4.40 in masseter and from about pCa 5.82 to 4.40 in digastric. The maximum tension was 75.5 +/- 10.2 g/mm2 in temporalis, 44.7 +/- 14.1 g/mm2 in masseter, and 46.1 +/- 20.1 g/mm2 in digastric. In the resting state, the sarcomere length at Lo was 2.34 +/- 0.06 micron in temporalis, 2.20 +/- 0.08 micron in masseter, and 2.20 +/- 0.00 micron in digastric. When the sarcomere length was stretched from 2.20 to 2.34 micron (the sarcomere length of temporalis at Lo) in the masseter and digastric, the Ca2+ sensitivity increased without significant change of the maximum tension in either muscle. The transient tension responses in all three muscles showed two distinct phases; an immediate tension increase coincident with the length stretch followed by an exponential tension decrease. The mean value of the time constant in the second phase was 58.5 +/- 19.7 ms in temporalis, 58.5 +/- 12.6 ms in masseter, and 362.6 +/- 16.8 ms in digastric. Thus temporalis showed a higher Ca2+ sensitivity at Lo and a greater maximum tension-producing capability than the other muscles and the cross-bridge turnover rate appears to be slower in digastric than in the others.

Animals↗
PubMed1985

Nucleotide sequence of the beta-lactamase gene of alkalophilic Bacillus sp. strain 170.

A gene for the beta-lactamase from alkalophilic Bacillus sp. strain 170 was cloned in a functional state on a 1.0 kb DNA fragment and its nucleotide sequence was determined. The coding sequence showed an open reading frame of 257 amino acids, which represents the beta-lactamase precursor protein. It is considered that the signal peptide consisted of 30 amino acids including 12 hydrophobic amino acids.

Amino Acid Sequence↗
PubMed1985

Cloning of a developmentally regulated element from alkalophilic Bacillus subtilis DNA.

An alkalophilic Bacillus DNA bank cloned in an expression probe plasmid, pGR71, was screened for the presence of developmentally regulated genetic elements. A 508-base pair HindIII fragment isolated from this bank in plasmid pGR71-5 expressed plasmid-encoded chloramphenicol resistance only during the sporulation phase of a Bacillus subtilis host grown on Schaeffer medium. This developmentally regulated expression was altered in spo0E and spo0H mutants which had very low levels of chloramphenicol acetyltransferase activity relative to the wild type or other spo0 mutants. We determined the nucleotide sequence of the entire 508-base pair fragment and located the site of regulated transcription initiation by high-resolution S1 nuclease mapping of the in vivo transcript. The deduced promoter sequences upstream from this start site were 5'C-G-A-A-T-C-A-T-G-A3' at -10 and 5' A-G-G-A-A-T-C3' at -35. This transcript was not detected in spo0E or spo0H mutants, indicating that the products of these genes control developmentally regulated chloramphenicol acetyltransferase expression at the level of transcription.

Acetyltransferases↗
PubMed1984

Effects of Ba2+ on the mechanical properties of glycerinated heart muscle.

At a muscle length, L0 (just taut), isometric tension and tension transients in response to rapid step stretches in length (mostly less than 1.2% of L0 within 2 ms) were measured at constant levels of Ba2+ activation of varying magnitude in glycerinated cat right-ventricular papillary muscles (2-3 mm long, 130-200 micron in diameter). The majority of the experiments were carried out at room temperature (26-27 degrees C) and at a pH of 6.8. The steady isometric tension increased as Ba2+ was varied from slightly below pBa 6 to about pBa 4. The concentration range of Ba2+-activated muscle was roughly 10 times higher than that of Ca2+-activated muscle. Maximum Ba2+-activated isometric tension was 79.0 +/- 4.2% (mean +/- SD, n = 8) of that activated with Ca2+. The tension transients in Ba2+-activated muscle were characterized by at least three distinct phases; an immediate tension increase coincident with the stretch, a rapid exponential tension decrease (time constant, tau 1 = 7.3 +/- 1.0 ms, n = 5) and a delayed exponential tension rise (tau 2 = 104 +/- 5.7 ms, n = 5). The profile of tension response was quite similar to that of Ca2+-activated muscle. These results suggest that in Ba2+-activated glycerinated heart muscle the cross-bridge turnover is taking place as in the Ca2+-activated muscle, but the number of active cross-bridges at maximally activated state is smaller than that of Ca2+-activated muscle.

Animals↗
PubMed1984

Mechanical properties of glycerinated guinea-pig temporal and masseter muscles.

At a muscle length, L0 (just taut), isometric tension and tension transients in response to rapid step stretches in length (less than 1 per cent of L0 within 2 ms) were measured at constant levels of Ca2+ activation of various magnitudes in glycerinated temporal and masseter muscles (1.7-2.5 mm long, 48-96 micron in diameter) from guinea pigs. The experiments were at 20 and 30 degrees C, and pH 6.8. Steady isometric tension increased in a sigmoid fashion as Ca2+ varied from about pCa 6.6 to 4.4 in both muscles. However, the maximum tension of temporal muscle was about 4.4 times greater than that of masseter muscle at 20 degrees C. The tension transients showed an immediate tension increase coincident with the stretch (the first phase) and an exponential-like tension decrease (the second phase). The time constant of the second phase was about 87.5 ms in temporalis and 3.7 ms in masseter at 30 degrees C. Decreasing temperature from 30 to 20 degrees C markedly increased the time constant of the tension response in the second phase (Q10 of about 3.4 in temporalis and 2.2 in masseter). Although there was a difference in the sarcomere length between the two muscles at L0 (2.14 micron in temporalis and 1.84 micron in masseter), the mechanical characteristics were almost independent of the muscle length. Thus the cross-bridges in temporalis appear to cycle more slowly and produce more isometric tension than those in masseter muscle.

Animals↗
PubMed1984

Cloning of leucine genes of alkalophilic Bacillus No. 221 in E. coli and B. subtilis.

The leucine genes of alkalophilic Bacillus No. 221 were cloned into the HindIII sites of pBR322 and pGR71, and recombinant plasmids pHK101 and pHK111 were constructed. The cloned 7.2 kb DNA consisting of HindIII fragments of 4.0 kb and 3.2 kb could substitute for leucine genes (alpha-isopropylmalate (alpha-IPM) synthetase gene, beta-IPM dehydrogenase gene, and alpha-IPM isomerase gene) of E. coli and B. subtilis, but not ilvB gene of B. subtilis. The 4.0 kb HindIII fragment could substitute for alpha-IPM synthetase gene of E. coli, and the 3.2 kb HindIII fragment could substitute for alpha-IPM isomerase gene of E. coli. Both 4.0 kb and 3.2 kb fragments are necessary to substitute for beta-IPM dehydrogenase gene. The expression of beta-IPM dehydrogenase gene of alkalophilic Bacillus No. 221 was repressed by the addition of leucine in the culture medium of B. subtilis carrying the plasmid pHK111. These results indicated that the 7.2 kb fragment contains the leucine gene cluster and its regulatory region.

3-Isopropylmalate Dehydrogenase↗
PubMed1984

Radical production during tyrosinase reaction, dopa-melanin formation, and photoirradiation of dopa-melanin.

It has been suggested that superoxide anion (O2-) may be produced during eumelanin formation and during the photoirradiation of eumelanin , but no direct evidence for this has yet been reported (although O2- production during photoirradiation of pheomelanin has been shown). In this report, the production of O2- was investigated during the formation and photoirradiation of dopa-melanin, a synthetic eumelanin . It was found that cytochrome c was reduced during the tyrosinase reaction and dopa-melanin formation in vitro; this reduction could not be inhibited by superoxide dismutase (SOD). When dopa-melanin was irradiated by UV radiation or by visible light, high nitroblue tetrazolium (NBT) reduction was observed; this reduction was proportional to the light energy and the amount of dopa-melanin. NBT reduction by visible light could be slightly inhibited by SOD, but a 12% decrease of NBT reduction by UV radiation could be shown with the addition of SOD. These observations indicate that some radicals were produced during the tyrosinase reaction and dopa-melanin formation. Further, when dopa-melanin was irradiated, radicals were also produced, some of which were thought to consist of O2-, but others were unknown.

Catechol Oxidase↗
PubMed1983

Transfer of tyrosinase to melanosomes in Harding-Passey mouse melanoma.

The transfer of tyrosinase from microsomes into melanosomes, without passing through the cytosol in the Harding-Passey mouse melanoma cell, was confirmed by experiments carried out using a combination of radioisotope tracer techniques and immunoprecipitation. 3H-Labeled amino acid incorporation into tyrosinase present in the microsome, melanosome, and soluble fractions confirmed the precursor-product relationship of the enzyme in the microsome fraction and in the melanosome fraction. However, two forms of the enzyme, Ts1- and Ts2-tyrosinase, separated from the soluble fraction by polyacrylamide gel electrophoresis, were shown to play no role in the transfer since little or no incorporation of radioactivity into tyrosinase in this fraction was found. It is suggested that most tyrosinase observed in the soluble fraction does not leak from the melanosomes or the microsomes during homogenization, but comes from necrotic tumor cells. It appears that melanosomal and microsomal tyrosinase might be released from the membrane of necrotic cells modified by various degradation enzymes, considering the data on the recovery of tyrosinase from the soluble fraction, where one-third of total enzyme activity in the postnuclear fraction could not be increased, even when the postnuclear fraction of the tumor was further homogenized radically.

Animals↗