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Biomedical subjects

H Kuroda

Publications and source records attributed to H Kuroda.

At least 289 records · Page 16Linked to original sources
PubMed1987

Effect of photoperiod, injection of pentobarbitone sodium or lesion of the suprachiasmatic nucleus on pre-partum decrease of blood progesterone concentrations or time of birth in the rat.

In Sprague-Dawley rats kept under 14L:10D (lights on 05:00-19:00 h), parturition occurred during the light phase on Day 23, and the pre-partum decrease in progesterone concentrations was observed between 07:00 and 15:00 h during the light period on Day 22. When the rats were transferred to reversed light-dark regimen (lights on 17:00-07:00 h) on Day 7, the progesterone decrease and parturition still occurred during the light period on Day 21 and 22-23, respectively. However, when rats were kept in constant darkness from Day 7, parturition occurred independently of the time of day between Day 22 and 24. A gradual decline of progesterone concentrations was randomly observed in individual rats. In Wistar rats kept under the usual light-dark regimen, parturitions were biphasic, occurring during the light periods on Day 22 and 23. The progesterone decrease occurred at the usual time even when the lighting regimen was changed only on the day of the expected progesterone decrease. However, treatment with pentobarbitone sodium at 15:00, 19:00 or 21:00 h, but not at 12:00 or 23:00 h, on Day 21 resulted in a delay of progesterone decrease and of parturition. Complete lesion of the suprachiasmatic nucleus on Day 13 or 14 led to advancement and random distribution of the time of birth. These results suggest that the time of parturition and of pre-partum progesterone decrease may be closely associated with an endogenous circadian system, and a luteolytic factor involving the nervous system may be present during a limited period before parturition.

Animals↗
PubMed1987

Synthesis and antitumor activity of spergualin analogues. II. Chemical modification of the spermidine moiety.

Chemical modifications of the spermidine moiety of an antitumor antibiotic, spergualin (Ia), and the structure-activity relationship are described. Replacement of spermidine with other polyamines decreased the antitumor activity against mouse leukemia L1210. Analogues containing an oxidized spermidine moiety that probably formed during oxidation with amine oxidase were inactive. Spermidine is indispensable for the antitumor activity. A facile method for the synthesis of glyoxyloyl polyamine, a key intermediate of spergualin-related compounds, is also reported.

Animals↗
PubMed1987

Synthesis and antitumor activity of spergualin analogues. III. Novel method for synthesis of optically active 15-deoxyspergualin and 15-deoxy-11-O-methylspergualin.

Optically active 15-deoxyspergualin (II) and 15-deoxy-11-O-methylspergualin (IIa) were synthesized, and their antitumor activities were examined. The (-)-enantiomers of both II and IIa were active against mouse leukemia L1210, while the (+)-enantiomers were almost inactive. The optical resolution of the key intermediate, (+/-)-N-(7-guanidinoheptanoyl)-alpha-alkoxyglycine (VI) was achieved by use of an exopeptidase, serine (acid) carboxypeptidase [EC 3.4.16.1] and (+/-)-N-(7-guanidinoheptanoyl)-alpha-alkoxyglycyl-L-amino acid (VIII) as the substrate. Considering the enzymatic susceptibility of the substrate (VIII), we deduced that the absolute configuration of the carbon at 11 (C-11) of the bioactive (-)-enantiomer, and so that of natural spergualin (I), is S. This is, to our knowledge, the first report of the use of carboxypeptidase for the resolution of N-acyl amino acid.

Animals↗
PubMed1987

OF4949, new inhibitors of aminopeptidase B. V. Effect on the murine immune system.

OF4949-I inhibited the growth of the solid form of IMC carcinoma and protected against pulmonary metastases of Lewis lung carcinoma. It also augmented the cytostatic activity of mouse peritoneal macrophages, the natural killer activity, and the antibody-dependent cell-mediated cytotoxicity of mouse spleen cells. This substance was not cytotoxic to cultured tumor or normal cells even at high concentrations. These results suggest that a cell-mediated immune response stimulated by this compound might account for its antitumor activity.

Aminopeptidases↗
PubMed1986

Effects of dynorphin1-13 on opiate binding and dopamine and GABA uptake in stroked cat brain.

We previously reported that the opioid peptide dynorphin1-13 improves survival chances in stroked cats. Some evidence also suggests that changes in dopamine and gamma-aminobutyric acid (GABA) uptake may be associated with stroke. In the present study, therefore, we determined binding of the opiate [3H]ethylketocyclazocine (EKC), as well as dopamine and GABA uptake in various brain regions of control, stroked and dynorphin1-13-treated stroked cats. Cats were stroked by middle cerebral artery occlusion. In the EKC binding study, the Kd of the high-affinity site of the occluded cortex was significantly increased, relative to that of both the unoccluded side and control cortex. Dynorphin1-13 treatment reversed this effect, lowering the Kd to control level. In the dopamine uptake study, the Km was decreased and Vmax was increased significantly in unoccluded cortex, compared with that in the occluded cortex or in control cortex. Again, dynorphin1-13 reversed these effects, raising the Km and lowering the Vmax. However, the Km of occluded cortex was also increased so that it became significantly higher than that of control cortex. The Km of unoccluded subcortex in stroked cats treated with dynorphin1-13 was significantly reduced compared with control. In the GABA uptake study, there was no significant change in any parameter. The change in opioid binding observed here and its reversal by dynorphin1-13 are consistent with the notion that the peptide's beneficial effect on stroke is mediated through opiate receptors. Since opioid systems in the brain are known to have association with dopaminergic ones, the change in dopamine uptake could also be the result of an opioid effect.

Animals↗
PubMed1986

Effect of genetically defined oocyte depletion on production of androgens and oestrogens by ovaries of suckling mice.

Steroid production and histological features of ovaries were compared either among normal +/+ mice of 3-12 days of age or among 12-day old mutant mice with various degrees of oocyte depletion. Whole ovaries were cultured in the medium containing [3H]progesterone and hCG or 4-androstene-3,17-dione and FSH; amounts of [3H]androgens or oestrogens released from the ovaries were assayed. FSH-responsive aromatase activity was detectable in ovaries of +/+ mice on day 3 after birth (2.6 +/- 0.4 pmol/2 ovaries/48 h), but the activity producing androgens from progesterone, under stimulation of hCG, was not detectable even on day 6 after birth (less than 0.1 pmol/2 ovaries/48 h). The androgen-producing activity appeared on day 9 after birth (1.16 +/- 0.25 pmol/2 ovaries/48 h), when follicles with more than two layers of granulosa cells developed. The ovaries of 12-day old Sl/Slt mice contained a considerable number of follicles with a single layer of granulosa cells, but did not contain any follicles with more than two layers of granulosa cells. The ovaries of Sl/Slt mice possessed aromatase activity (3.3 +/- 0.4 pmol/2 ovaries/48 h) but, not androgen-producing activity (less than 0.1 pmol/2 ovaries/48 h). The present results suggest that development of follicles with more than two layers of granulosa cells may induce the activity producing androgens from progesterone under stimulation of LH in suckling mouse ovaries, though the FSH-responsive aromatase activity is present even in follicles with a single layer of granulosa cells.

Androgens↗
PubMed1986

Survival effect of coenzyme Q10 and naloxone on experimental stroke gerbils.

Coenzyme Q10 (CoQ10) and the opiate antagonist naloxone were compared as to their effect on the survival of mongolian gerbils with unilateral carotid ligation-induced stroke. Without medication all of the stroke gerbils died within 28 hours, but with a subcutaneous implantation of a 10 mg pellet of naloxone, 20% of the gerbils lived for 4 weeks. When a 250 mg pellet of CoQ10 was implanted subcutaneously, a definite effect on survival was observed, with 45% of the stroke gerbils living for 4 weeks. Considering that the action mechanisms of CoQ10 and naloxone are different, the combined use of these drugs in the treatment of stroke needs to be investigated.

Animals↗
PubMed1986

Optimal calcium concentration in the initial reperfusate for post-ischemic myocardial performance (calcium concentration during reperfusion).

The dose-response curves of calcium concentration in the initial reperfusate to mechanical recovery of ischemic myocardium was investigated with an isolated working rat heart preparation. After 20 mins of normothermic ischemic arrest, the recovery of aortic flow by reperfusion with Krebs-Henseleit buffer was 54.0 +/- 2.4% (mean +/- S.E.M.). Reduction of calcium concentration during 10 mins of initial reperfusion after 20 mins of normothermic ischemic arrest increased or decreased the recovery of aortic flow with a bell-shaped dose-response curves obtained. The maximal percent recovery of aortic flow was 75.2 +/- 1.7 at 0.5 mM calcium with normal potassium-normal magnesium solution, 74.9 +/- 3.1 at 0.1 mM with high potassium (20 mM)-normal magnesium solution, 65.4 +/- 1.5 at 1.2 mM with high potassium-high magnesium (20 mM K, 16 mM Mg) solution, and 73.4 +/- 2.7 at 1.3 mM with normal potassium-high magnesium (16 mM) solution. All of them were significantly better than that of the control group (P less than 0.01). A high concentration of potassium and magnesium affected the dose-response of calcium in the initial reperfusate. These results suggest that the control of calcium concentration in the reperfusate is important during the early stages of reperfusion, and reperfusion injury may be considerably reduced.

Animals↗
PubMed1986

A case of nontraumatic clostridial gas gangrene occurring in a patient with colon adenocarcinoma, liver cirrhosis, and diabetes mellitus.

An autopsy case of clostridial gas gangrene occurring in a 54-year-old man with colon adenocarcinoma, liver cirrhosis, and diabetes mellitus is reported. The patient died 4 days after the onset of symptoms with episodes of vomiting and abdominal pain. Gangrene of both hips and perineum, hemolysis, renal failure, and disseminated intravascular coagulation were the dominant clinical features. Clostridium septicum was isolated from the subcutaneous tissue fluid. Adenocarcinoma of the ascending colon with ulceration found at autopsy was supposed to be an entry of the organism. Histologically, lesions of subcutaneous tissue and muscles were characterized by the absence of inflammatory infiltrates in spite of extensive necrosis. A summary of 35 cases of gas gangrene hospitalized to the Osaka University Hospital for the past 16 years indicates that clostridial gas gangrene patients with underlying diseases such as malignant neoplasm, diabetes, liver cirrhosis or immunodeficiency have a relatively poor prognosis.

Adenocarcinoma↗
PubMed1986

OF4949, new inhibitors of aminopeptidase B. I. Taxonomy, fermentation, isolation and characterization.

New aminopeptidase B inhibitors that we named OF4949-I, II, III and IV were isolated from the culture broth of a fungus, Penicillium rugulosum OF4949. The molecular formula of I was C23H26N4O8 and that of II, C22H24O8, judging from elemental analysis and secondary ion mass spectrometry. The concentrations of I, II, III and IV required for 50% inhibition of aminopeptidase, using Ehrlich ascites carcinoma cells as the source of the enzyme, were 0.0054, 0.0048, 3.4 and 1.7 micrograms/ml, respectively. Components I and II augmented delayed-type hypersensitivity in mice to sheep red blood cells.

Aminopeptidases↗