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Biomedical subjects

J Kato

Publications and source records attributed to J Kato.

At least 595 records · Page 33Linked to original sources
PubMed1981

Stimulation of protein synthesis in round spermatids from rat testes by lactate. II. Role of adenosine triphosphate (ATP).

The stimulatory effects of glucose and lactate on protein synthesis by round spermatids (steps 1-8) were further studied. When the cells were incubated with lactate, the response of protein synthesis in round spermatids was closely related to the intracellular level of ATP. The ATP level in spermatids increased to 3.13 +/- 0.20 nmol/10(6) cells from 0.37 +/- 0.02 nmol/10(6) cells after incubation of the cells at 34 degrees C for 60 min in the presence of lactate (20 mM). However, the ATP level fell rapidly to an undetectable level (less than 0.02 nmol/10(6) cells) during incubation for 30 min at 34 degrees C without lactate. The ATP level and the rate of protein synthesis in spermatids increased rapidly when lactate (20 mM) was added to the control cells during incubation. It was also found that incorporation of 32P into ATP was increased by treatment with lactate (20 mM), but glucose (10 mM) had no effect on 32P incorporation into ATP. When the rates of utilization of glucose and lactate by spermatids were examined, using 14C-labeled glucose and lactate, the rate of utilization of lactate was faster than that of glucose. These results suggest that the ATP is probably a major factor in the stimulation of protein synthesis in round spermatids.

Adenosine Triphosphate↗
PubMed1981

Progesterone receptors in the cerebral cortex of neonatal female rats.

Progestin-binding components were detected in cerebral cortical cytosols from female rats at 7 days of age. These components labeled in vitro with a tritiated synthetic progestin. R5020, sediment in the 7S region in sucrose density gradients containing 10% glycerol. The dissociation constants and the number of binding sites of the components were 3.9 X 10(-10)M and 47.5 fmol/mg cytosol protein, respectively, indicating high affinity and low capacity binding. The 7S-binding components were specific for progestational compounds. Estradiol competed weakly. Incubation with pronase abolished the 7S progestin binding. Heat experiments suggested a thermolabile nature of the components. These results suggest that the cytosols from the cerebral cortex of 7-day-old female rats contain progesterone receptors.

Animals↗
PubMed1981

Stimulation of protein synthesis in round spermatids from rat testes by lactate.

Lactate markedly increased the rate of [3H]leucine incorporation into the protein of isolated round spermatids (steps 1-8) from rat testes. Four kinds of hexoses, glucose, fructose, galactose, and monnose, also stimulated [3H]leucine incorporation, but to much lesser extents than lactate. Ribose had no effect. The glucose-induced stimulation of protein synthesis was entirely suppressed by iodoacetate and NaF, whereas iodoacetate and NaF were without effect on the lactate-induced increase in protein synthesis. Lactate stimulated both protein synthesis and ATP production in the spermatids. However, both of these stimulatory effects of lactate were completely blocked by DNP and rotenone. Rotenone entirely blocked oxygen consumption, as expected, whilst DNP enhanced it additively with lactate. Moreover, lactate was without influence on either transport of alpha-[3H]AIB into spermatids or incorporation of [3H]leucine into protein of a cell-free system of spermatids. These findings suggest that lactate may increase the protein synthesis of spermatids in the same fashion as glucose, and that the effect of lactate in increasing the level of ATP during incubation in vitro may be a major factor in the mechanism of stimulation of protein synthesis in the spermatids.

Adenosine Triphosphate↗
PubMed1980

The presence of progesterone receptors in the sexual skin of the monkey.

R5020(17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione)-binding components with sedimentation coefficient of 8S were detected in sexual skin cytosols from estrogen-primed ovariectomized Japanese monkey (Macaca fuscata fuscata). In contrast, little 8S binding was found in similar preparations from the abdominal skin. The dissociation constants and the number of binding sites of the components were 1.6 x 10(-10)M and 36 fmoles/mg cytosol protein, respectively. The 8S binding components were specific for progestational compounds. Incubation with pronase abolished the 8S binding. Thermal experiments revealed the thermolabile nature of the components. Moreover, the concentration of the R5020-binding components was markedly increased by estradiol-17 beta 3-benzoate injections. We conclude from these results that the cytosols from the sexual skin of estrogen-primed female monkeys contain progesterone receptors.

Animals↗
PubMed1980

Excretion of glutathione by methylglyoxal-resistant Escherichia coli.

A methylglyoxal-resistant mutant of Escherichia coli B excreted glutathione into the growth medium, especially during growth on medium containing methylglyoxal. In the presence of methylglyoxal, the total amount of glutathione excreted was increased about 50-fold over that of the wild-type strain. The resistant mutant had high activities of two enzyme systems: a glutathione-forming enzyme system (consisting of gamma-glutamylcysteine synthetase and glutathione synthetase) and a glyoxalase system (consisting of glyoxalase I and glyoxalase II). Methylglyoxal resistance appeared to be due to the simultaneous increase in the activities of these two enzyme systems.

Drug Resistance, Microbial↗
PubMed1980

Isolation and Identification of a Senescence-promoting Substance from Wormwood (Artemisia absinthium L.).

The senescence-promoting substance of wormwood (Artemisia absinthium L.) as detected by the oat (Avena sativa L. cv "Victory") leaf assay has been identified as (-)-methyl jasmonate, methyl (1S, 2R)-3-oxo-2-(2'-cis-pentenyl)-cyclopentane-1-acetate, by gas-liquid chromatography-mass spectrometry and optical rotatory dispersion. Its senescence-promoting effect was much stronger than that of abscisic acid, and even at such a low concentration as 1 to 2.5 micrograms per milliliter, it could completely eliminate the anti-senescence action of 2 micrograms per milliliter kinetin. Comparing the biological activity of the (-)- with the (+/-)-forms of methyl jasmonate, it seemed that only the (-)-form was biologically active.

Journal Article↗
PubMed1980

Dynamics of the estrogen receptor in the uteri of mice treated neonatally with estrogen.

Experiments were performed to examine the uterine response to estrogen and the dynamics of uterine estrogen neonatally. Uterine tissue of neonatally estrogenized mice showed a markedly reduced response to estrogen in the adult. The concentration of cytoplasmic estrogen receptor in the uteri of such mice was markedly lower than that of neonatally vehicle-injected control mice. Nuclear and cytoplasmic estrogen receptors of uteri in both groups were determined by the exchange assay at various intervals after injection of estradiol. Nuclear translocation of estrogen receptor complexes in neonatally estrogenized mice was similar to that in control mice. The concentration of cytoplasmic receptor decreased to low levels by 1 h and began a gradual increase from 1-16 h after injection in both groups. Between 16-24 h after injection, however, the level of cytoplasmic receptor continued to increase in control mice but almost ceased to increase in neonatally estrogenized mice. Ten daily injections of estradiol continued to increase the concentration of cytoplasmic estrogen receptor in control mice. On the other hand, in neonatally estrogenized mice treated daily with estradiol, the receptor level reached a plateau on day 5. These data suggest that the induction of new uterine estrogen receptor under the influence of estrogen may be altered by neonatal estrogen treatment.

Aging↗
PubMed1980

Hetero-transplantation of human endometrial carcinoma into nude mouse. Effects of sex steroid hormones on morphological aspects of undifferentiated adenocarcinoma cells.

Seven cases of human endometrial carcinoma were transplanted into nude mice. Two of these cases, histologically classed as undifferentiated adenocarcinoma, were succeeded in the initial transplantation, but only 1, designated JEA-1, was established as serially transplanted tumor line in nude mice, which contained no estrogen and progesterone receptors assayed by sucrose density gradient centrifugation. JEA-1 tumor cells transplanted serially maintained the morphological and the functional characteristics of the original human tumor. Consequently, the JEA-1 tumor line will be useful for the experimental model of cancer treatments and the analysis of sensitivity for sex steroid hormones. Effects of sex steroid hormones on JEA-1 tumor cells had been examined and the electron microscopic observation and in receptor level, alteration of the tumor tissue were found. Ultrastructurally, the tumor cells which had been administrated estradiol and progesterone revealed various morphological changes resembling that of normal endometrial epithelium in the proliferative and the secretory phase, respectively. In addition, in the tumor tissue which had been administrated estradiol, the low, but positive, estrogen receptor sites were detectable. These findings may suggest that means of estradiol exposure will be able to induce the estrogen and progesterone receptors in endometrial carcinoma initially without these hormone receptors.

Adenocarcinoma↗
PubMed1979

Continuous production of NADP by immobilized Brevibacterium ammoniagenes cells.

Whole cells of Brevibacterium ammoniagenes IAM 1645 having the polyphosphate NAD-kinase were successfully immobilized in a polyacrylamide gel lattice. The immobilized cells were activated by treatment with organic solvents or detergents. The pH optimum of the immobilized cells for the production of NADP was 7.0, and divalent metal ions were required to maintain the elevated activity of polyphosphate NAD-kinase. Highly pure NADP was continuously produced in high yield by the immobilized cell column. The half-life of this column was about eight days.

Brevibacterium↗