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Biomedical subjects

M Shimizu

Publications and source records attributed to M Shimizu.

At least 793 records · Page 44Linked to original sources
PubMed1994

Left ventricular dysfunction during exercise in patients with angina pectoris and angiographically normal coronary arteries (syndrome X)

Left ventricular function during exercise and recovery was investigated in patients with angina pectoris, ST segment depression during exercise and angiographically normal coronary arteries (syndrome X) using a continuous left ventricular function monitor with cadmium telluride detector (CdTe-VEST). Fourteen patients with syndrome X and 14 patients with atypical chest pain without ST segment depression during exercise and normal coronary arteries (control group) performed supine ergometric exercise after administration of 740-925 MBq of technetium-99m labelled red blood cells, and left ventricular function was monitored every 20 s using CdTe-VEST. Left ventricular ejection fraction (EF) response was impaired (< or = 5% increase from rest to peak exercise) in 11 or 14 patients with syndrome X but in none of the control patients. Resting EF was similar in the two groups (62.1% +/- 6.7% in patients with syndrome X, 61.9% +/- 6.2% in controls); however, EF increase from rest to peak exercise was lower in syndrome X (-3.1 +/- 9.5% vs 14.7% +/- 7.4%, P < 0.001). After cessation of exercise, all patients showed rapid EF increase over baseline and this EF overshoot was lower (19.3% +/- 8.3% vs 26.4% +/- 7.3%, P < 0.001) with the time to EF overshoot longer (114 +/- 43 s vs 74 +/- 43 s, P < 0.05) in patients with syndrome X. Thus, in patients with syndrome X, left ventricular dysfunction was frequently observed during exercise in spite of normal epicardial coronary arteries.

Adult↗
PubMed1994

A human gene that restores the DNA-repair defect in SCID mice is located on 8p11.1-->q11.1.

In order to map the gene that is responsible for the DNA-repair defect in severe combined immune deficient (SCID) mice, a mixture of microcells independently isolated from mouse A9 cells containing pSV2neo-tagged human chromosomes 5, 7, 8, 9, 11, 15, 18 or 20 were fused with SCID fibroblast cell lines SCVA2 and SCVA4, which were originally established from lung tissue of the C.B.17-scid/scid mouse by SV40 virus transfection. After irradiation with 60Co gamma-rays and selection with antibiotic G418, 12 independent clones were obtained, of which 4 contained an intact chromosome 8, 3 clones contained a deleted chromosome 8 [del(8)q22-->qter or del(8)q23--> qter] and remaining 5 had no detectable or specific human chromosome. We further independently transferred a single human chromosome 8 or 11 into the SCVA cells via microcell fusion, and examined the radiation sensitivity of the microcell hybrids. Complementation of the radiation sensitivity was correlated with the presence of human chromosome 8 in microcell hybrids, whereas no correlation was observed in clones following the transfer of human chromosome 11. Thus, the results indicate that human chromosome 8 restored high sensitivity to ionizing radiation. A number of subclones that were radiation resistant or sensitive were isolated from the microcell hybrids. The concordance of the radiation sensitivity with the presence or absence of specific DNA fragments on chromosome 8 indicates that the human gene is located on the centromeric region of chromosome 8, i.e., 8p11.1--> q11.1.

Animals↗
PubMed1994

Porcine amelogenins.

Amelogenins were extracted from the thin outer layer of porcine secretory enamel and purified by gel filtration and reverse-phase HPLC. The results of amino acid sequencing of the purified porcine amelogenins indicated the presence of at least four prototype amelogenins translated from alternatively spliced transcripts. The results of mass spectroscopy of the CNBr-cleaved peptides derived from the 25 kDa amelogenin indicated that porcine 25 kDa amelogenin is neither phosphorylated nor glycosylated.

Amelogenin↗
PubMed1994

Fuzzy and conventional control of high-frequency ventilation.

A high-frequency ventilator was developed, consisting of a single-phase induction motor, an unbalanced mass and a mechanical vibration system. Intermittent positive pressure respiration was combined with high-frequency ventilation to measure end-tidal pCO2. Hysteresis was observed between the rotational frequency of the high-frequency ventilator and end-tidal pCO2. A fuzzy proportional plus integral control system, designed on the basis of the static characteristics of the controlled system and a knowledge of respiratory physiology, successfully regulated end-tidal pCO2. The characteristics of gas exchange under high-frequency ventilation was approximated by a first-order linear model. A conventional PI control system, designed on the basis of the approximated model, regulated end-tidal pCO2 with a performance similar to that of the fuzzy PI control system. The design of the fuzzy control system required less knowledge about the controlled system than that of the conventional control system.

Animals↗
PubMed1994

Degradation of enamelins by proteinases found in porcine secretory enamel in vitro.

The action of proteinases obtained from porcine secretory enamel on the porcine 89-kDa enamelin was examined in vitro. The results of sodium dodecyl sulphate-acrylamide gel electrophoresis of the reaction products indicated the following. (1) The 76- and 78-kDa proteinases localized in the outermost layer of the secretory enamel not only convert the 25-kDa amelogenin to the 20-kDa amelogenin, but also split the 89-kDa enamelin, which is the major enamelin component in the enamel in the very early secretory stage, into large fragments such as 25-, 41- and 56-kDa enamelins. (2) The serine proteinases localized in the inner layer of secretory enamel further degrade not only amelogenins but also enamelins.

Amelogenesis↗
PubMed1994

Paeoniflorin attenuates learning impairment of aged rats in operant brightness discrimination task.

The effects of paeoniflorin isolated from peony were examined on an aging-induced learning deficit in an operant brightness discrimination task in Fischer 344 rats. Learning in aged (25 months) rats was significantly impaired compared with young (5 months) rats. Daily administration of paeoniflorin (0.01 mg/kg, PO) significantly attenuated the learning impairment in aged rats, whereas it did not affect the learning in young rats. Although tacrine (0.3 and 1 mg/kg, IP), a cholinesterase inhibitor, also did not affect the learning in young rats, it slightly augmented the aging-induced learning deficit in the present task. These data indicate the therapeutic potential of paeoniflorin in the treatment of senile dementia and aging-induced cognitive dysfunction.

Aging↗
PubMed1994

Cerebral pial arterial innervation with special reference to GABAergic innervation.

Glutamic acid decarboxylase (GAD)-immunoreactive (I) nerve fibers were observed to run parallel to other autonomic nerve fibers, especially vasoactive intestinal polypeptide (VIP)- and calcitonin gene-related peptide (CGRP)-I nerve fibers at the light microscopic level. At the ultrastructural level, GAD-immunoreactivities co-localized with CGRP immunoreactivities in nerve terminals, but not with choline acetyltransferase, VIP, tyrosine hydroxylase and neuropeptide Y immunoreactivities. GAD immunoreactivities were observed in the trigeminal ganglion, some of which were co-localized with CGRP-immunoreactivities. In the proximal portion of the internal carotid artery, GAD-I adventitial ganglion cells were observed and some were also immunoreactive for CGRP. These results strongly suggest that the origin of GABAergic innervation of the major cerebral pial arteries of the cat is mainly in the trigeminal ganglion, and partly in the adventitial ganglia of the internal carotid artery.

Animals↗
PubMed1994

Monoclonal antibodies recognising differentiation antigens on porcine B cells.

Nineteen monoclonal antibodies (mAbs) submitted to the porcine CD Workshop were analysed on porcine B cells from different lymphoid tissues by flow cytometry and immunohistochemistry. Six mAbs only bound to pig B cells and three of these were assigned cluster numbers, 76-7-4 (No. 001):CD1, K231-3B2 (No. 027):CD25 and CC51 (No. 100):CD21. Of the three remaining B cell positive mAbs, one was assigned to a swine cluster, CC55 (No. 101):SWC7, a second, LIG4 (No. 123), recognised cell surface IgM and the third, MUC106A (No. 072), remained unassigned.

Animals↗
PubMed1994

The role of insulin in coronary atherosclerosis.

In 197 patients with coronary artery disease (CAD) who underwent coronary angiography, 75 g oral glucose tolerance test (OGTT) was performed, measuring plasma glucose(PG) and plasma insulin (IRI) at 4 time points (0, 30, 60 and 120 min). Subjects were separated into two groups by their insulinogenic index (I.I. = delta IRI/delta PG from 0 up to 30 min), 99 cases with good insulin response (I.I. > or = 0.4) and 98 cases with poor insulin response (I.I. < 0.4). Only two subjects were diabetic in good insulin response, while 37 were diabetic in poor insulin response. The severity of coronary atherosclerosis was expressed as a coronary index (CI), calculated according to Balcon's method. Fasting PG and the sum of PG were significantly higher in the latter group, while the sum of IRI was significantly lower. CI was not significantly different, however. In the group with good insulin response, the severity of CAD was significantly correlated to fasting IRI (n = 99, r = -0.387, P < 0.02), but, there was no such relationship in the other group. We conclude that hyperinsulinemia might be a risk factor for ischemic heart disease, but in diabetics it is difficult to link the relationship between fasting IRI and CI.

Adult↗
PubMed1994

Ischemic heart disease in patients with diabetes mellitus in Japan.

The risk of death by ischemic heart disease (IHD) in patients with diabetes mellitus is higher than in non-diabetics, and the average life span of the diabetics is shorter than in non-diabetics in Japan. There is no direct correlation between the occurrence of IHD and severity or glycemic control of diabetes. However, the mortality by IHD increases in diabetic patients with severe retinopathy and/or massive proteinuria. Regarding the management of IHD, diabetes is not considered a contraindication to thrombolytic therapy. The indication and results of percutaneous transluminal coronary angioplasty and coronary bypass surgery are the same as in non-diabetics.

Adolescent↗
PubMed1994

Current status of pregnancy in diabetic women. A comparison of pregnancy in IDDM and NIDDM mothers.

Pregnancy in diabetic patients was uncommon before 1960 in Japan. It has increased recently and there has been a 3-fold increase since 1971. Only 26% of the cases of diabetic pregnancy had IDDM; the rest of cases had NIDDM. The perinatal mortality of infants decreased from 10.8% in 1971-1975 to 1.1% in 1986-1990, but the incidence of congenital malformations remained at 5.7-8.2% during this period. From 1988 to 1992, we experienced 207 deliveries at the Diabetes Center, Tokyo Women's Medical College. The ratio of IDDM to NIDDM of the mothers was 33:67. The onset of diabetes of pregnant women occurred earlier and the duration of diabetes was longer in IDDM than in NIDDM (mean onset, 17.8 vs. 26.0 years; mean duration, 11.5 vs. 5.6 years). The prevalence of maternal complications was similar between the IDDM and NIDDM mothers. Proliferative retinopathy in NIDDM was often detected for the first time during pregnancy. Major congenital malformations were found in none of the infants of IDDM mothers but in 5.8% of the infants of NIDDM mothers. This is probably related to the poor management of diabetes in NIDDM before pregnancy.

Adult↗
PubMed1994

Imipramine stimulates phospholipase C activity in rat brain.

We previously demonstrated that antidepressant drugs (ADs) cause Ca2+ release from inositol 1,4,5-trisphosphate-sensitive Ca2+ stores in cultured neurons of rat frontal cortex. The present study examines the mechanism by which tricyclic ADs activate phospholipase C (PLC) in rat frontal cortex. Using an exogenous substrate to measure PLC activity, we demonstrated that a tricyclic AD, imipramine, stimulated PLC activity of the frontal cortex membrane in a concentration-dependent manner. Two tricyclic ADs, desipramine and amitriptyline, also stimulated PLC activity, while Li+ or pargyline had no effect on PLC activity. Although imipramine did not activate PLC in the membrane in the absence of Ca2+, imipramine synergistically activated PLC in the presence of Ca2+. This result indicates that the mechanism of PLC activation by imipramine is different from its activation by Ca2+. Imipramine stimulated PLC activity in the cytosol of rat frontal cortex as well as in the membrane. Preincubation of the cytosol with anti-PLC-beta 1 antibody prevented the imipramine-mediated activation of PLC. However, preincubation with anti-PLC-gamma 1 or anti-PLC-delta 1 did not prevent activation of PLC. These results suggest that imipramine activates PLC-beta 1 directly without receptor or guanine nucleotide binding protein mediation.

Animals↗
PubMed1994

Effects of TRI-n-butyl phosphate on pregnancy in rats.

A teratological study was carried out on the plasticizer tri-n-butyl phosphate (TBP). Pregnant Wistar rats were treated orally on days 7-17 of gestation with TBP at 0, 100, 200, 400 or 800 mg/kg/day in the dose-finding study and 0, 62.5, 125, 250 or 500 mg/kg/day in the subsequent teratological study. Caesarean sections were performed on day 20 of gestation. In the dose-finding study, all of the pregnant rats were killed by the treatment with TBP at 800 mg/kg/day. In the teratological study, salivation and depression of body weight gain, adjusted body weight gain and food consumption were observed at the higher doses of TBP. There were no significant differences between the groups in the incidence of dead or resorbed foetuses, the number of living foetuses and the body weights of living foetuses of both sexes. The incidence of rudimentary lumbar rib increased significantly at 500 mg/kg/day. There were two cases of malformation: a foetus with deformity of fore- and hind-limbs at 400 mg/kg/day in the dose-finding study and conjoined twins exhibiting three fore-limbs and four hind-limbs at 125 mg/kg/day in the teratological study. These malformations were rare in the background data of teratology, and the incidence of foetuses with malformations was not increased significantly. Therefore, TBP was considered not to be teratogenic in this study.

Administration, Oral↗
PubMed1994

A comparison of the antihepatotoxic activity between glycyrrhizin and glycyrrhetinic acid.

A comparison of antihepatotoxic activities between glycyrrhizin (18 beta-GL) and its genuine aglycone, glycyrrhetinic acid (18 beta-GA), was carried out using in vivo and in vitro assay methods. The oral administration of 18 beta-GA at 1, 24, and 48 h before D-galactosamine (GalN) treatment significantly reduced the increase of serum transaminase activities 24 h after GalN treatment, whereas 18 beta-GL did not inhibit the increase of serum transaminase activities. The intraperitoneal administration of 18 beta-GA 1 h before GalN treatment restored the increase of serum transaminase activities with lower doses than 18 beta-GL. In CCl4-induced cytotoxicity of primary cultured rat hepatocytes, 18 beta-GA protected the CCl4-induced leakage of transaminase at doses of 5 to 50 micrograms/ml, whereas 18 beta-GL inhibited slightly the leakage at a dose of 1000 micrograms/ml. In the same way, 18 alpha-GA, the alpha-isomer of 18 beta-GA, reduced the CCl4-induced cytotoxicity more strongly than 18 alpha-GL. Furthermore, the adsorbability of 18 alpha, beta-GA on primary cultured rat hepatocytes was higher than that of 18 alpha, beta-GL. These results suggest that 18 alpha, beta-GA is a more potent antihepatotoxic agent than 18 alpha, beta-GL, and that the potency of the antihepatotoxic compounds parallels their adsorbability in hepatocytes.

Animals↗
PubMed1994

Bellidifolin: a potent hypoglycemic agent in streptozotocin (STZ)-induced diabetic rats from Swertia japonica.

Hypoglycemic activity-guided fractionation led to the isolation of five known xanthones and two triterpenoids from the ethyl acetate soluble fraction of Swertia japonica and their identification was based on spectroscopic methods. One of the triterpenes, thysanolactone, was first isolated from this plant. Among the xanthones, bellidifolin showed a potent and dose-dependent hypoglycemic activity in STZ-induced diabetic rats both in i.p. and p.o. administration. A comparative hypoglycemic activity of the other three xanthones together with bellidifolin was also studied.

Animals↗
PubMed1994

Intramyocardial angiomyolipoma.

We report a case of cardiac angiomyolipoma in a 48-year-old woman who went to the hospital because of shortness of breath. Cardiac ultrasonography showed a right atrial mass, which was surgically removed. Pathologic examination revealed a 6-cm-diameter, dome-shaped mass composed of a mixture of blood vessels, smooth muscle, and fat. Because of its distinctive morphology and location, we diagnosed it as an intramyocardial angiomyolipoma. There was no evidence of tuberous sclerosis. Since excision of the mass, the patient has remained well without recurrence for 20 months. Angiomyolipomas usually develop in the kidney; extrarenal occurrence is rare. To date, no case of a cardiac angiomyolipoma has been reported in the English literature. The histogenesis of angiomyolipoma is uncertain, but it is most likely hamartomatous in nature.

Angiomyolipoma↗
PubMed1994

Diffuse increased renal uptake on bone scintigraphy in acute tubular necrosis.

Acute renal failure after exercise with frank pain and patchy renal vasoconstriction is a clinical syndrome that occurs in young, previously healthy persons. The authors describe a 24-year-old man who had this syndrome. CT scan showed wedge-shaped contrast enhancement of both kidneys, which suggested patchy renal vasoconstriction. Tc-99m MDP imaging revealed diffuse increased uptake of both kidneys. After renal function was improved, Tc-99m MDP imaging showed normal uptake of both kidneys. Acute renal failure due to acute tubular necrosis was confirmed by renal biopsy. The authors conclude that Tc-99m MDP may be useful in evaluation of acute renal failure after exercise with flank pain and patchy renal vasoconstriction due to acute tubular necrosis.

Adult↗