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Biomedical subjects

K Shiraki

Publications and source records attributed to K Shiraki.

At least 217 records · Page 12Linked to original sources
PubMed1993

Iron-saturated lactoferrin as a co-mitogenic substance for neonatal rat hepatocytes in primary culture.

We studied the effect of lactoferrin on DNA synthesis in neonatal rat hepatocytes in primary culture to determine if this agent acts as a mitogen in human milk. Thymidine incorporation into the DNA of cultured hepatocytes stimulated by lactoferrin in the presence of insulin and human epidermal growth factor was examined. Iron-saturated lactoferrin increased DNA synthesis of neonatal hepatocytes by 1.5 times and this potency was the same as that of insulin. It significantly enhanced the stimulatory effect of human epidermal growth factor plus insulin; DNA synthesis under these conditions was seven times that of control. Iron-free lactoferrin did not affect DNA synthesis, nor did the exogenous addition of ferric ions. The enhancement of DNA synthesis by iron-saturated lactoferrin was significant for neonatal hepatocytes, but not for adult hepatocytes. These results suggest that iron-saturated lactoferrin, which itself had low mitogenic activity, is a co-mitogenic substance for neonatal hepatocytes in vitro.

Animals↗
PubMed1993

Cardiac-renal-neural reflex plays a major role in natriuresis induced by left atrial distension.

The role of cardiac-renal-neural reflex in the natriuresis induced by left atrial balloon inflation was investigated in conscious dogs. Female mongrel dogs were assigned randomly to 1) sham-operated (n = 8), 2) cardiac-denervated (n = 6), and 3) renal-denervated (n = 8) groups. The dogs were chronically instrumented with a bipolar stainless steel wire electrode for measurement of renal sympathetic nerve activity (RSNA). Balloon inflation induced a step increase in left atrial pressure (Pla) by 7.7 +/- 1.7 mmHg, a step decrease in RSNA (-66.6 +/- 5.5%), and concomitant increases in urine flow (441 +/- 142%), osmolal excretion (60 +/- 12%), and sodium excretion (300 +/- 69%) in sham-operated dogs. Renal denervation abolished the diuresis and natriuresis during balloon inflation. Chronic cardiac denervation abolished also the diuresis and natriuresis in the face of a similar increase in Pla. RSNA did not change significantly throughout the experimental period in cardiac-denervated dogs. It is concluded that a sustained reduction of RSNA originating from left atrial mechanoreceptors plays a major role in the natriuresis during left atrial distension in conscious dogs.

Animals↗
PubMed1993

Efficacy of bromocriptine administration for selective pituitary resistance to thyroid hormone.

The relation between thyroid-stimulating hormone (TSH) and triiodothyronine (T3) was evaluated in a girl with the selective pituitary type of thyroid hormone resistance for more than 7 years to clarify whether bromocriptine was an effective treatment or not. Levels of T3 (before: 2.44 +/- 0.64 nmol/l, mean +/- SD) and TSH (4.81 +/- 2.52 mU/l) were significantly decreased during therapy (T3: 2.15 +/- 0.44 nmol/l; TSH: 1.59 +/- 0.78 mU/l). T3 x TSH, calculated as one of the indices of pituitary resistance, on bromocriptine therapy (3.229 +/- 1.255 mU/l x nmol/l) was significantly (p < 0.005) smaller than the product before the administration (11.298 +/- 5.891 mU/l x nmol/l). The results suggest that bromocriptine should be one of the agents initially considered for the treatment of pituitary resistance to thyroid hormone.

Bromocriptine↗
PubMed1993

Elevated venous concentrations of vasoactive intestinal polypeptide in cord blood of infants with fetal distress.

Concentrations of vasoactive intestinal polypeptide (VIP) in cord plasma were determined in 70 neonates (birth weight, mean +/- SD, 3,213.5 +/- 50.9 g, gestation 39.5 +/- 0.2 weeks), 22 of whom had fetal distress. Arterial VIP levels in cord blood were not significantly different between infants with and without fetal distress. The mean venous VIP in cord blood of distressed infants (28.1 +/- 8.4 pg/ml, mean +/- SE) was significantly (p < 0.05) higher than that of normal neonates (12.6 +/- 3.4 pg/ml). The mean placental content of VIP was 5.1 +/- 0.3 ng/g wet tissue, although a correlation with the venous concentration in the cord was not demonstrated. Venous VIP levels were elevated 24 h after birth (34.6 +/- 13.7 pg/ml) and decreased on the 5th day of life to 12.9 +/- 3.8 pg/ml, which was not significantly different from the mean VIP level in childhood (14.7 +/- 3.1 pg/ml). These results demonstrate that, in the perinatal period, plasma VIP levels are elevated on two occasions: at delivery associated with fetal distress (cord vein), and at 24 h of age. VIP in the former seems to be of placental and/or maternal origin.

Arteries↗
PubMed1993

Eating attitudes test in boys and girls aged 6-18 years: decrease in concerns with eating in boys and the increase in girls with their ages.

Concerns with eating were studied in 130 Japanese boys and 125 girls aged 6-18 years using the Simplified Eating Attitudes Test (s-EAT). The s-EAT scores in girls slightly increased with age. The mean scores in girls at age 10 years or older were significantly higher than in boys of the same age, suggesting that pubertal girls have more concerns with eating. On the other hand, s-EAT scores in boys that were not overweight decreased as they grew older, contributing, at least partly, to the sexual difference in eating behavior. The mean scores in overweight boys were higher than in boys that were not overweight. The score in boys correlated significantly with weight though there was no significant correlation in girls. These results suggest that, in addition to increased concerns with eating in girls, decreased concerns with age in boys is one of the causes of the sexual difference in eating behavior, especially during puberty. Eating behaviors in girls seem to be less influenced by changes in body weight than in boys.

Adolescent↗
PubMed1993

Isolation and structure of woodorien, a new glucoside having antiviral activity, from Woodwardia orientalis.

Hot aqueous and methanol extracts of the rhizomes of Woodwardia orientalis were tested for their in vitro antiviral activity against herpes simplex virus type 1 (HSV-1), poliovirus type 1, and measles virus by plaque reduction assay. The aqueous extract of W. orientalis reduced the plaque forming ability of HSV-1 and poliovirus more strongly than did the methanol extract. By bioassay-directed fractionation of the aqueous extract, a new glucoside, woodorien (1), along with five known compounds were isolated from an EtOAc-soluble fraction that had antiviral activity. The structures of these compounds were determined by the use of two dimensional (2D) NMR techniques (1H-1H correlation spectroscopy (COSY), 1H-13C COSY and heteronuclear multiple-bond multiple-quantum coherence (HMBC)). Woodorien (1) was the most potent inhibitor against HSV-1 among the isolated compounds.

Animals↗
PubMed1993

Hepatitis in an adult with rubella.

Rubella was accompanied by hepatic dysfunction in a 28-year-old male. Serum aminotransferase levels were moderately elevated and LDH markedly increased, especially LDH isoenzyme 5, whereas total bilirubin and ALP remained almost normal. GOT, GPT and LDH levels were completely normalized by the 21st hospital day. Paired antibody titers of viruses which may cause hepatitis, other than rubella, were of no significance. Laparoscopy showed enlarged, red liver. Histologic and electron microscopic findings of the liver were consistent with acute hepatitis. Hepatic damage with rubella is rare, and it is possible that the hepatic dysfunction seen in adult rubella may be mediated by an immunopathologic mechanism.

Acute Disease↗
PubMed1993

[Recombinant Oka varicella vaccine as a live hepatitis B virus vaccine].

Recombinant Oka varicella-hepatitis B virus (HBV) vaccine was constructed by inserting the HBV surface antigen (HBsAg) gene coding partial PreS2 and whole S regions into the viral thymidine kinase gene. HBsAg was expressed in the cytoplasm of infected cells. Intracellular HBsAg (26K and 30K) was N- and O-glycosylated, sialylated, and secreted into the supernatant as 30K and 35K HBsAg particles. Recombinant virus induced antibody response to both varicella-zoster virus and HBsAg in guinea pigs and the level of antibody titers to HBsAg was comparable in guinea pigs immunized with a live varicella-HBV vaccine or commercial HBs subunit vaccine. Altogether, this recombinant virus may be a good candidate for the live varicella-HBV vaccine.

Animals↗
PubMed1993

Cardiovascular responses to upright tilt at a simulated altitude of 3,700 m in men.

To examine the effects of high altitude on cardiovascular responses to orthostasis, 11 healthy males were tested at a 10-min passive 70 degrees head-up tilt at sea level and at a simulated high altitude of 3,700 m. During the control period in the supine position, heart rate and forearm blood flow were higher at high altitude (p < 0.05). Mean arterial pressure remained unchanged during head-up tilt at sea level, but it reduced from 82 mm Hg to 72 mm Hg (p < 0.05) during head-up tilt at high altitude. There were no altitude-related changes in the magnitude of the increase in forearm vascular resistance and the reduction in cardiac output and laser-Doppler skin blood flow in response to head-up tilt. The total peripheral resistance increased from 14.4 to 20.5 mm Hg.L-1 x min-1 (p < 0.05) during head-up tilt at sea level, but the change was not significant at high altitude. The lack of altitude-related changes in forearm vascular resistance and laser-Doppler skin blood flow during head-up tilt in the presence of attenuated total peripheral resistance response at high altitude may suggest that the orthostatic hypotension at high altitude is associated with a lower magnitude of vasoconstrictor response in the regions other than the limbs and the skin.

Adult↗
PubMed1992

Fat distribution in overweight patients with Ullrich-Turner syndrome.

Overweight patients with Ullrich-Turner syndrome (UTS) and control children with similar weight/height and indices of overweight were studied to clarify the unique fat distribution in the syndrome. Triceps and ulnar skin-fold thickness (SFT) in UTS patients was significantly less than that of obese children without the syndrome. The means of SFT at the subscapular and paraumbilical regions were also less in the patients than control girls, though significance was not documented. Thus, increased body weight in UTS children seems mainly to be due to excess of adipose tissue, not in the limbs but on the trunk, and/or due to the increment of lean body mass.

Adipose Tissue↗
PubMed1992

Toxicity test of biodegradable polymers by implantation in rabbit cornea.

To evaluate whether or not the corneal micropocket implantation is effective for determining the toxicity of polymeric materials, currently used biodegradable polymers such as poly(lactic acid) (PLA), poly(glycolic acid) (PGA), LA-GA copolymers, and three kinds of poly(2-cyano-acrylate)s (PCA) were implanted in a rabbit corneal pouch and the tissue responses were observed macroscopically and microscopically. It was found that PLA induced no vascularization, whereas a residual solvent and ethylene oxide gas remaining in the PLA matrix invoked vascularization. Vascularization clearly took place when PGA was implanted in the cornea, which became opaque, probably because of cellular infiltration. In the case of PCA implantation, severe inflammation as well as vascular invasion occurred in the initial stage. It is likely that these tissue reactions were caused by the leachables from the implanted materials, the extent being dependent on the leaching rate and the toxicity. It was concluded that the corneal micropocket assay is a good means to detect trace amounts of leachables from implanted materials without sacrificing the animals with the implanted materials.

Animals↗
PubMed1992

Infection enhancement of influenza A NWS virus in primary murine macrophages by anti-hemagglutinin monoclonal antibody.

Antibody-dependent enhancement (ADE) of influenza A NWS virus infection was investigated in primary murine macrophages (M phi) using anti-hemagglutinin(HA) monoclonal antibody (mAB). Contrary to previous reports of abortive influenza virus infection in primary M phi, this study demonstrated that the NWS virus replicated productively in both resident peritoneal M phi and thioglycolate-elicited peritoneal M phi providing cleavage of the HA was achieved by trypsin; 5 micrograms/ml of trypsin was the optimum concentration for the induction of infectivity. Under multiple-cycle growth conditions in the presence of mAB at various concentrations in trypsin-containing media, ADE was demonstrated in both M phi in the presence of subneutralizing concentrations of mAB. Flow cytometric analysis showed that the mechanism of virus entry into M phi could be through HA to specific virus receptors, or HA plus antibody to Fc receptors. These results indicate that ADE of the NWS virus infection actually occurs on Fc receptor-bearing primary murine M phi depending on the concentration of antibody in the presence of the appropriate protease for cleavage of viral HA.

Animals↗
PubMed1992

Yucca leaf protein (YLP) stops the protein synthesis in HSV-infected cells and inhibits virus replication.

Yucca leaf protein (YLP), an inhibitor of tobacco mosaic virus isolated from the leaves of Yucca recurvifolia Salisb., exhibited potent activity against herpes simplex virus type 1 (HSV-1) with no cytotoxicity below 300 micrograms/ml. The inhibitory dose was varied with the time of addition; 50% effective concentrations (ED50) of YLP were 3, 19 and 95 micrograms/ml when YLP exposure was begun 3 h before virus infection, 0 h and 3 h after infection, respectively. This protein also inhibited the multiplication of herpes simplex virus type 2 and human cytomegalovirus. YLP has been shown to have a weak virucidal activity at higher concentrations. Analysis of early events following infection showed that YLP affected viral penetration in HeLa cells but did not interfere with adsorption to the cells. YLP was found to exert strong inhibition of protein synthesis in virus-infected cells but not in uninfected cells. This selective effect can be considered to attribute mainly to the antiviral activity of YLP.

Animals↗
PubMed1992

Comparison of antiviral assay methods using cell-free and cell-associated varicella-zoster virus.

Assay methods for varicella-zoster virus (VZV) susceptibility to acyclovir (ACV) of VZV were compared by using cell-free (CF) and cell-associated (CA) virus of 6 x plaque-purified VZV. The 50% effective doses (ED50) of ACV, as required to reduce virus plaque formation by 50%, were about 8 times higher for CA virus than for CF virus. Also, the ED50 of 1-beta-D-arabinofuranosyl-(E)-5-(2-bromovinyl)uracil (BVaraU) for CA-VZV was higher than for CF-VZV, and fresh clinical isolates of VZV gave higher ACV ED50 values than CF virus. CA virus prepared at various times after CF virus infection showed a gradual increase of the ACV ED50 with time, ranging from the ED50 for CF virus to that for CA virus.

Acyclovir↗
PubMed1992

Mother-to-infant transmission of hepatitis C virus.

Prospective studies of an infant of a mother infected with hepatitis C virus indicated that an HCV infection developed in the infant in early life. Perinatal transmission appeared to be the most likely explanation.

Female↗
PubMed1992

Refractoriness at peripheral and pituitary receptors in general and pituitary types of thyroid hormone resistance.

Patients with the general type (patient #1 and #2) and the selective pituitary type (#3) of thyroid hormone refractoriness (TR) were studied to clarify defects at peripheral and pituitary receptors. Products of T3 and TSH (n = 63) were calculated when T3 was above the normal limit (T3 > 1.8 ng/ml, 2.8 nmol/l) as one of the indices of pituitary resistance. Means of T3 (ng/ml) x TSH (mU/l) of patient #1 (mean; 40.8), #2 (15.0) and #3 (8.6) were significantly greater than patients with Graves' disease (2.1), suggesting pituitary refractoriness in the 3 patients. The products of patient #1 and #2 were also significantly larger than patient #3, demonstrating that the pituitary insensitivity in the latter (#3) was less than the former patients. Means of serum cholesterol in patients #1 and #2 were higher than patient #3 and patients with Graves' disease. Products of T3 (ng/ml) and cholesterol (mg/ml) (n = 28) in the patient #1 (541.9) and #2 (461.0) were significantly greater than the patient #3 (292.8) and the patients with Graves' disease (275.3). The results demonstrate generalized refractoriness in the patient #1 and #2 and selective pituitary resistance in the patient #3. It is suggested that our patient with the pituitary type (#3) had less severely affected receptors at the pituitary than our two patients with the general type. These results are consistent with the previous hypothesis that the pituitary type of TR is a partial form of this disease.

Child↗