Biomedical subjects

H Shibata

Publications and source records attributed to H Shibata.

At least 595 records · Page 33Linked to original sources

PubMed1987

Analysis of promoters of adenovirus type 12 E1A gene in a cell-free transcription system.

Transcription from the E1A gene of adenovirus type 12 initiates at two sites in vivo. In this paper we analyzed the E1A promoter(s) in a cell-free transcription system. Primer extension assay revealed that transcriptions were accurately initiated at two sites apart by 140 bp. The efficiency of transcriptions from two sites was almost equal in the standard reaction. However, when transcription reaction was done following pre-incubation of a nuclear extract and template DNA in the absence of ribonucleotides, transcription from the site proximal to E1A gene significantly decreased with little effect on that from distal site. This suggests the existence of a mechanism which controls the efficiency of transcriptions from two start sites of E1A gene.

Adenoviridae↗

PubMed1987

Erythroid differentiation factor stimulates hydrolysis of polyphosphoinositide in Friend erythroleukemia cells.

We examined an early action of erythroid differentiation factor (EDF), a polypeptide which induces differentiation of Friend murine erythroleukemia (MEL) cells. (Eto et al., Biochem. Biophys. Res. Commun. 142: 1095-1103, 1987). In MEL cells, EDF caused a rapid and transient increase in cytoplasmic concentration of free calcium, [Ca2+]c. EDF increased [Ca2+]c even in the absence of extracellular calcium. When [3H]inositol-labeled MEL cells were incubated with EDF, EDF rapidly increased radioactivity in inositol trisphosphate, bisphosphate and monophosphate. EDF also increased [3H] diacylglycerol in [3H]arachidonate-labeled MEL cells. These results indicate that EDF increases [Ca2+]c by stimulating hydrolysis of polyphosphoinositide.

Activins↗

PubMed1987

Time-dependent restoration of the trigger pool of calcium after termination of angiotensin II action in adrenal glomerulosa cells.

In adrenal glomerulosa cells, angiotensin II causes an immediate release of calcium from an intracellular trigger pool (Kojima, I., Kojima, K., and Rasmussen, H. (1985) Am. J. Physiol. 247, E36-E43). The present study was conducted to determine how the trigger pool of calcium is restored after cessation of the agonist action. Upon termination of angiotensin II action, calcium influx rate decreased immediately while total cell calcium increased rapidly. The increase in total cell calcium is not affected by 1 microM nitrendipine, which blocks angiotensin II-stimulated calcium influx without inhibiting basal influx of calcium. In contrast, total cell calcium did not increase in medium containing 1 microM calcium, in which basal calcium influx is negligible. A rapid increase in total cell calcium after an addition of the antagonist was not accompanied by changes in cytoplasmic free calcium concentration. A second stimulation of cells with either angiotensin II or carbachol did not cause calcium release when the interval of two stimulations was shorter than 20 min. The longer the interval, the greater the magnitude of calcium release in response to the second stimulator. The maximum response was obtained when the interval was 40 min or more. When exogenous arachidonic acid, which mobilized calcium by acting directly on the inositol trisphosphate-sensitive pool, was employed as a second stimulator, the magnitude of the decrease in total cell calcium was also dependent on the interval. These results suggest that, upon termination of angiotensin II action, calcium is rapidly accumulated first in an intracellular pool which is insensitive to either inositol 1,4,5-trisphosphate or arachidonic acid and that the trigger pool is restored gradually thereafter.

Adrenal Glands↗

PubMed1987

Peroxidative injury of the mitochondrial respiratory chain during reperfusion of hypothermic rat liver.

Mitochondrial dysfunction in ischemic liver has been demonstrated to be due to decrease in the intramitochondrial level of ATP and the subsequent disruption of the proton barrier of the inner membrane (Watanabe, F., Hashimoto, T. and Tagawa, K. (1985) J. Biochem. 97, 1229-1234). In this study, another injury process, impairment of the electron-transfer system, which occurred during reoxygenation of ischemic liver, was studied during reperfusion of cold preserved liver and during cold incubation of isolated rat-liver mitochondria. The sites of the respiratory chain that were sensitive to peroxidative damage were ubiquinone-cytochrome c oxidoreductase and NADH-ubiquinone oxidoreductase. These enzymic activities decreased with increase in lipid peroxidation. Incubation of submitochondrial particles with t-butyl hydroperoxide or with an NADPH-dependent peroxidation system decreased the enzymic activities of the electron-transport system. These data strongly suggested that lipid peroxidation during reoxygenation of ischemic liver impaired the electron-transfer system. Thus, mitochondria of ischemic liver suffer from two different types of injury: increase in proton permeability during anoxia, and decrease in enzymic activities of the electron-transport system during reoxygenation.

Animals↗

PubMed1987

Depression and body image following mastectomy and lumpectomy.

A twenty year debate about the appropriate surgery for breast cancer has resulted in two clinical trials comparing radical vs more conservative operations. Despite the favorable results of these trials, the majority of breast cancer patients in North America still undergo mastectomy. We investigated the psychological and social adjustment following total and partial mastectomy in a group of patients randomly assigned to one or the other operation (National Surgical Adjuvant Breast Protocol--B-06). Total mastectomy patients showed higher levels of depression and less satisfaction with body image. Partial mastectomy patients did not display any measurable increase in fear of recurrence. Patients undergoing radiation therapy showed surprising increase in depressive symptoms. Radiation therapy could well be more frightening to breast surgery patients than had been anticipated. These patients may benefit from some anticipatory counselling.

Body Image↗

PubMed1987

Serum total and HDL cholesterols according to reproductive status in Japanese females.

In order to observe variations according to reproductive status, serum total cholesterol (TC) and HDL cholesterol (HDL-C) were investigated in 153 pregnant, in 153 age-adjusted non-pregnant females, in 787 females aged 45-54 years living in a northern suburb of Tokyo, and in 150 12-year-old girls from a private junior high school in a southern suburb of Tokyo. Non-menstruating (non-menarcheal, postmenopausal) females had significantly higher TC and significantly lower HDL-C/TC than menstruating (menarcheal, premenopausal) females did in both the age groups of 12 and 45-54 years, although no significant difference of HDL-C was found between them. The menstruating females tended to be more overweight in Quetelet's index and had thicker skinfolds. Pregnant females at the eighth month of gestation revealed a significantly high value of both TC and HDL-C vs age-adjusted non-pregnant females, while at the fourth month of gestation only HDL-C was high.

Adolescent↗

PubMed1987

The effect of forced running on heat production in brown adipose tissue in rats.

The effect of running on heat production in brown adipose tissue (BAT) was compared between trained and untrained rats. Rats were forced to run a treadmill while temperatures of colon (T col) and interscapular BAT (T bat) were measured. The daily running for 5 weeks neither changed the size of interscapular BAT nor the norepinephrine-induced thermogenesis (8 micrograms/kg X min). During running, both T bat and T col increased. In rats trained for 2 weeks, the increases in T bat were similar to those in T col. In untrained rats, however, the increases in T bat were larger than those in T col. It is suggested that exercise increases heat production in BAT in untrained rats, but such heat production in BAT is abolished by daily exercise. Exercise suppresses cold-induced heat production in BAT of trained rats.

Adipose Tissue, Brown↗

PubMed1987

On the molecular mechanism of DNA translocation during in vitro packaging of bacteriophage T3 DNA.

The process of packaging of bacteriophage T3 DNA in a defined in vitro system can be separated into two stages: formation of a precursor complex (50 S complex) in the presence of adenosine-5'-O-(3'-thiotriphosphate) (ATP-gamma-S) and subsequent translocation of DNA into the head by the addition of ATP. Packaged DNA exits when DNA translocation is interrupted by the addition of ATP-gamma-S (M. Shibata, H. Fujisawa, and T. Minagawa, 1987, Virology, in press; M. Shibata, H. Fujisawa, and T. Minagawa, 1987, J. Mol. Biol., in press). The in vitro system packaged nicked and cross-linked DNAs but did not package single-stranded DNA. DNA packaging was inhibited by intercalating reagents such as ethidium bromide, acridine orange, and 4',6-diamino-2-phenylindole dihydrochloride. The inhibitory effect was proportional to the ability of intercalating agents to unwind DNA. Ethidium bromide did not inhibit the formation of 50 S complex but blocked translocation of DNA into and out of the capsid. DNA packaging was inhibited by actinomycin D and distamycin A which bind to the minor groove of the DNA helix. From these results, we conclude that DNA packaging mechanism utilizes the exterior structure of duplex DNA for translocating the DNA into the capsid.

Capsid↗

PubMed1987

Early events in DNA packaging in a defined in vitro system of bacteriophage T3.

We have developed a defined in vitro system for packaging phage T3 DNA which is composed of purified proheads and the noncapsid proteins gp18 and gp19, products of genes 18 and 19. The reaction requires Mg2+, ATP, and polyethylene glycol and is inhibited by a nonhydrolyzable ATP analog, adenosine-5'-O-(3'-thiotriphosphate) (ATP-gamma-S) (K. Hamada, H. Fujisawa, and T. Minagawa, 1986, Virology 151, 119-123). About 30% of added mature T3 DNA was packaged into heads in the defined system. A complex with a sedimentation coefficient of about 50 S (50 S complex) accumulated in the reaction mixture containing ATP-gamma-S. The 50 S complex was DNase sensitive and was converted to filled heads by a second reaction in the presence of ATP without addition of DNA, proheads, gp18, and gp19. These results indicate that during early stages of DNA packaging, formation of precursor complexes proceeds by an allosteric mechanism with ATP acting as effector. The movement of DNA into the head is driven by the energy released by hydrolysis of ATP. gp18 formed a complex with DNA without addition of ATP-gamma-S and gp19. gp18-DNA complex was DNase sensitive and did not bind gp19; it was converted to filled heads by way of a second reaction after addition of ATP, gp19, and proheads. gp19 formed a functional complex with prohead in the presence of ATP-gamma-S or ATP. The complex did not bind gp18 but was converted to filled heads by incubation with ATP, gp18, and DNA. In the absence of ATP-gamma-S, gp19 formed complexes with prohead that were abortive in DNA packaging. Formation of the 50 S complex occurred in a reaction mixture containing gp18-DNA and gp19-prohead complexes in the presence of ATP-gamma-S. From these results, we propose details of the molecular mechanism of DNA packaging in the defined in vitro system.

Adenosine Triphosphate↗

PubMed1987

Differentiation-associated carbohydrate chain on human hematopoietic cells recognized by Clerodendron trichotomum lectin.

In the screening of hematopoietic cell line cell aggregations, the extract of Clerodendron trichotomum seed was found to aggregate K-562 and KG-1 specifically. In the flow cytometric analysis using FITC-conjugated purified CTL, it was confirmed that CTL recognizes the specific carbohydrate(s) which seem to appear only in the early stages of differentiation of myeloid (KG-1) and erythroid (K-562) cell line cells and erythrocytes. The CTL binding to K-562 cells was decreased by TPA treatment which is known to induce retrodifferentiation of K-562. It is also found that this carbohydrate(s) were shaded with NANA on the differentiated cells. In the erythrocyte, CTL receptor was partially shaded by NANA.

Carbohydrate Metabolism↗

PubMed1987

The role of insulin in nonshivering thermogenesis.

The regulation of nonshivering thermogenesis by insulin was studied in cold-acclimated rats (2 weeks at 5 degrees C) made diabetic after injection with streptozotocin (75 mg/kg, i.p.) and maintained in the warm (25 degrees C) for 2-7 days. To investigate whether thermogenesis was activated in brown adipose tissue (BAT) of diabetic rats under physiological conditions, conscious rats were briefly exposed to cold (2 h at 5 degrees C) and the temperature of interscapular BAT (Tbat) was compared with the colonic temperature (Tcol). It was found that Tbat, Tcol, and Tbat-Tcol (an index of thermogenesis activation in BAT) were significantly reduced in 7-day diabetic rats (P less than 0.01) but not in 2-day diabetic animals, suggesting that diabetes progressively decreases BAT thermogenic capacity. To further assess whether the maximal capacity of BAT for nonshivering thermogenesis was affected by the lack of insulin, the calorigenic response to noradrenaline (0.4 mg/kg, i.m.) was determined at 25 degrees C in anesthetized animals using an open circuit respirometer. The results showed that the calorigenic response to noradrenaline was inhibited by 50 and 70% in 2- and 7-day diabetic rats, respectively. Significantly, tissue weight, protein content, and cytochrome oxidase activity of interscapular BAT were also decreased by 30-40% and 50-70% in the same animals. Insulin treatment of 3-day diabetic rats for 4 days (6.5 U/day per rat) restored their calorigenic response to noradrenaline to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue, Brown↗

PubMed1987

Regulatory alterations of daily energy expenditure induced by fasting or overfeeding in unrestrained rats.

The consequences of fasting or overfeeding during 2 days on energy expenditure were investigated by continuously monitoring O2 consumption in unrestrained, unanesthetized rats. O2 consumption decreased by 15% on the 1st day of fasting and then by an additional 15% on the 2nd day. On the 3rd day, when rats were fed again, energy intake increased by 30% above control (prefasting) values, whereas energy expenditure rapidly increased but no more than control values. On the other hand, when ad libitum fed animals were offered a sucrose solution (32%) for 2 days, energy intake increased by 30% and energy expenditure by 9-12%. On the 3rd day, when the rats were fed with their normal diet, energy intake significantly decreased under control (preoverfeeding) values during one day, but energy expenditure rapidly returned to normal values. The results show that fasting decreases, whereas hyperphagia increases 24-h energy expenditure during the treatments. When the treatments are terminated, energy expenditure rapidly returns to normal values, but fasting induces a postfasting increase of energy intake (during 2 days), whereas hyperphagia, on the contrary, results in a transient decrease of appetite. This indicates that alterations of food intake induce compensatory changes of energy expenditure during the treatments, but that after the treatments, energy balance is normalized via regulatory adjustments in the ratio of energy expenditure over energy intake.

Animals↗

PubMed1987