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Biomedical subjects

K Shiraki

Publications and source records attributed to K Shiraki.

At least 181 records · Page 10Linked to original sources
PubMed1995

Cardiovascular deconditioning occurs during a 7-day saturation dive at 31 ATA.

Cardiovascular deconditioning (CD) has been reported to occur within 24-48 h of exposure to 4, 11, or 31 ATA environment and following decompression to sea level pressure. The CD was indicated by orthostatic intolerance, exaggerated cardiovascular responses to a passive tilt, an elevated resting heart rate and a reduced stroke volume postdive. In this dive, one of the New Seatopia series, we used a non-syncope criterion, the cardiovascular index of deconditioning (CID; Bungo MW, Johnson PJ Jr. Aviat Space Environ Med 1983; 54:1001), to evaluate CD in 3 male subjects. The CID sums the changes in heart rate and blood pressure in response to orthostatic stress. An elevated CID indicates CD. We used a passive 70 degrees head up tilt as the orthostatic stress. The CID was measured before and after a bout of underwater exercise at predive, during the early, mid, and late exposure of the 7-d 31 ATA, and after the dive. The CID and circulatory responses to tilt were similar before and after the exercise. The CID increased (p < 0.05) from the predive value of 20 +/- 1.6 to 25 +/- 0.9 on the 2nd day, to 25 +/- 0.8 on the 4th day at 31 ATA, indicating the presence of CD at the early and mid periods of hyperbaric exposure. However, CID was indifferent (18 +/- 0.6) from the predive on the 7th day at 31 ATA. The increased CID corresponded to decreases in plasma volume during the early and mid periods of 31 ATA exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Acute pancreatitis associated with acute intermittent porphyria].

Pancreatic involvement associated with acute intermittent porphyria is rare. There were only nine cases reported until now which have pancreatic disease and AIP, one case with chronic pancreatitis, one with cystadenocarcinoma and chronic pancreatitis, one with transient macroamylasemia and the others with acute pancreatitis. The cause of these complications in these patients is uncertain. However, in our case, it is possible that AIP might have caused the acute pancreatitis, since this patient developed acute pancreatitis following the attack of AIP. It seems to be necessary to pay attention to the combination of these diseases.

Acute Disease↗
PubMed1995

Diving patterns of ama divers of Hegura Island, Japan.

Daily diving patterns, especially depth-time profiles, were continuously recorded during the entire work shift in four cachido and four funado divers of Hegura Island, Japan. All Hegura divers (cachido and funado alike) were female and habitually wore wet suits. Cachidos dive free and unassisted from a boat or float, whereas funado divers are assisted by weighted descent and during the ascent by being pulled by a partner into a boat on the water surface. Both funado and cachido divers spent 250-280 min/day on the sea at their diving locations; the actual diving time was 100-120 min. The divers made 90-120 dives/day to a depth of 13-22 m, each dive lasting approximately 60 s, considerably longer and deeper than those observed and recorded previously in ama divers in the Chiba and Miura regions. These dive profiles are similar to those reported by Paulev in which he observed apparent signs of decompression sickness when the subject dived to a depth of 15-20 m 100 times in 5 h. The average bottom time for each dive of Hegura funados was 23.6 s which is approximately 10 s longer than that of Korean female ama. The rate of ascent in the funado divers was 1.5 m/s, which is nearly twice that of the cachido divers (0.8 m/s). The dive frequency of Hegura funados (109 dives/day) was greater than the Chiba male funados (23 dives/day). Accordingly, cumulative bottom time of Hegura funado was 48 min/day, whereas that of Chiba funado was 17 min/day.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Diurnal renal responses in man to water loading at sea level and 31 atm abs.

The hyperbaric environment causes a sustained diuresis accompanied by normal water intake and a decrease in insensible water loss. The maintained water intake may be necessary for the maintenance of water balance because of a reduced ability of the kidney to retain water, or may be causal in the diuresis. This problem was studied in four male subjects. Each ingested 1 liter of water (15 degrees C) at 0800 and 2000 h on different days, at 1 atm abs during a predive control, at 31 atm abs, and at 1 atm abs during the postdive control period. Urine was collected 30 min before and 3 h after the drink. Plasma vasopressin (VP) showed a circadian rhythm only at 1 atm abs, higher during the daytime. Because of this, and slightly lower VP levels at hyperbaria, a decrease in VP in response to the water load was significantly detectable only at 1 atm abs during the daytime. At 60 min after all water loads, there were no differences in plasma VP or plasma or urinary osmolality. Variability in the length of time of similarly reduced urine osmolality and increased free water excretion accounted for the increased urine flow during day compared to night (P < 0.05) at 120 and 150 min after the water load. The ability to excrete a water load both day (free water clear-ance, P < 0.05 at 60 min post-drink) and night (free water clearance, P < 0.05 at 60, 90, and 120 min post-drink) at 31 atm abs was enhanced. It is concluded that maintained water intake at hyperbaria is necessary to maintain water balance because there is a reduced ability of the body through renal mechanisms to retain a water load.

Adult↗
PubMed1995

Effects of naloxone, an opiate receptor antagonist, on coxsackievirus B3 myocarditis in the mouse.

OBJECTIVE: The aim was to test the therapeutic efficacy of naloxone, an opiate receptor antagonist, upon murine coxsackievirus B3 myocarditis with the analysis of neurohumoral kinetics. METHODS: Two week old C3H/He mice were inoculated with 10(3) plaque forming units of coxsackie B3 virus. Naloxone, 1 mg.kg-1.d-1, was given intraperitoneally daily on days 0-14 in experiment I, and on days 14-28 in experiment II. The treated groups were compared to infected controls in each experiment. For the analysis of the endogenous opiate and neurohumoral system, plasma beta endorphin and catecholamines were measured. RESULTS: In experiment I, survival rate did not differ significantly between naloxone treated and untreated groups (11/15 v 8/15, p = NS). Pathological scores (infiltration and necrosis), myocardial virus titres, and plasma beta endorphin and catecholamine concentrations did not differ significantly between the two groups. In experiment II, survival rate (13/16 v 6/14, P < 0.05) was higher and cardiac pathology was less severe, with a lower incidence of congestive heart failure, in naloxone than in controls groups. In addition, beta endorphin and noradrenaline were significantly increased in the naloxone group compared to the control. CONCLUSIONS: The endogenous opiate system is activated in congestive heart failure caused by severe myocardial damage in murine coxsackie B3 myocarditis, where an associated limitation of the sympathetic system may be present. Naloxone is beneficial in congestive heart failure caused by coxsackie B3 myocarditis because of its neurohumoral modulating effect.

Animals↗
PubMed1994

Functional roles of terminal glycomoieties in varicella-zoster virus infection.

Terminal glycomoieties of varicella-zoster virus glycoproteins were characterized by their reactivity with lectins and glycosidases, and the functional roles of terminal sugars were analyzed by cell-free virus infectivity. Terminal glycan structures of gpl possessed sialic acid linked alpha (2-3) to galactose of O-linked glycan and galactose-beta (1-4)-N-acetylglucosamine of N-linked glycan. Those of the putative gpIV possessed galactose-beta (1-4)-N-acetylglucosamine of N-linked glycan. Both glycoproteins had mannose alpha (1-3, 6, or 2) linked to mannose in their glycans. Their biological functions on cell-free virus infectivity were assessed by using lectins and exoglycosidases. Sialic acid of glycans on both the viral envelope and the cell surface had a negative effect on infectivity, and the latter had a larger effect on infectivity than the former. Maackia amurensis agglutinin, which recognizes sialic acid, enhanced infectivity more than expected from the simple neutralization of the negative effects of sialic acids between cells and virus. alpha-Mannosidase and alpha-glucosidase treatments of virus significantly reduced infectivity but those of cells did not. Therefore, alpha-mannose and alpha-glucose residues on the viral envelope had functional roles in cell-free virus infection. Inactivation of virus infectivity by concanavalin A was mainly due to the blocking of functional roles of terminal alpha-mannose and alpha-glucose residues of viral glycoproteins.

Acetylglucosamine↗
PubMed1994

Safety and efficacy of a recombinant yeast-derived pre-S2 + S-containing hepatitis B vaccine (TGP-943): phase 1, 2 and 3 clinical testing.

A recombinant yeast-derived pre-S2 + S-containing hepatitis B vaccine (TGP-943) was clinically evaluated through three phases of testing in a total of 2137 volunteers. We observed the immunogenic purity of TGP-943 (phase 1), the inter-lot reproducibility of both safety and immunogenicity (phase 2), no significant side-effects, a high capability of inducing both anti-HBs and anti-pre-S2 antibodies (phases 1, 2 and 3), and an ability to induce seroconversion in the majority of vaccines who had been non-responsive to conventional hepatitis B vaccines (phases 2 and 3). In conclusion, TGP-943 is a safe and tolerable vaccine, with special merits: the ability to induce an early anti-pre-S2 response that circumvents the problem of delayed appearance of anti-HBs, and efficacy in non-responders to previous vaccination.

Adolescent↗
PubMed1994

Effects of glycyrrhizin on hepatitis B surface antigen: a biochemical and morphological study.

Glycyrrhizin, a major component of a herb (licorice), has been widely used to treat chronic hepatitis B in Japan. This substance improves liver function with occasional complete recovery from hepatitis; its effects on the secretion of hepatitis B surface antigen (HBsAg) were examined in vitro. Glycyrrhizin suppressed the secretion of HBsAg and accumulated it dose-dependently in PLC/PRF/5 cells. Its action was further analyzed and determined in the HBsAg-expression system using the varicella-zoster virus. Glycyrrhizin suppressed the secretion of HBsAg, resulting in its accumulation in the cytoplasmic vacuoles in the Golgi apparatus area. HBsAg labeled with 35S-methionine and cysteine accumulated in the cells and its secretion was suppressed dose-dependently in glycyrrhizin-treated culture. The secreted HBsAg was modified by N-linked and O-linked glycans but its sialylation was inhibited dose-dependently by glycyrrhizin. Thus glycyrrhizin suppressed the intracellular transport of HBsAg at the trans-Golgi area after O-linked glycosylation and before its sialylation. HBsAg particles were mainly observed on the cell surface in the glycyrrhizin-treated culture but not in the untreated culture. This suggests that asialylation of HBsAg particles resulted in the novel surface nature of glycyrrhizin-treated HBsAg particles. We elucidated the unique mechanism of action of glycyrrhizin on HBsAg processing, intracellular transport, and secretion.

Antiviral Agents↗
PubMed1994

Effects of human neonatal serum on DNA synthesis in suckling and adult rat hepatocytes in primary culture.

The effect of human neonatal serum on DNA synthesis in suckling and adult rat hepatocytes in primary culture was investigated to characterize growth regulating factors of the liver in neonates and to confirm whether the stimulatory factor is human hepatocyte growth factor (hHGF). Neonatal serum stimulated DNA synthesis of both adult and suckling rat hepatocytes. The stimulatory effect was dose-dependent up to 20% in volume. The molecular weight of the stimulatory substance in neonatal serum was between 12,500 and 25,000, as estimated by gel filtration. Its activity was stable after heating at 56 degrees C for 20 min, but was lost after heating at 90 degrees C for 30 s, and easily passed through S- or heparin-Sepharose columns. The concentration of hHGF quantified by ELISA was too low to stimulate DNA synthesis in vitro. Biological and biochemical properties of the growth stimulatory activity in neonatal serum differed from that of hHGF. The presence of other growth factors in human neonatal serum for suckling and adult hepatocytes was suggested.

Animals↗
PubMed1994

Changes in muscle sympathetic nerve activity and renal function during positive-pressure breathing in humans.

The possibility that the decreased urinary flow during continuous positive-pressure breathing (CPPB) may be a consequence of a reflex mediated via the cardiopulmonary baroreceptors to increase neurohumoral secretion or to change the sympathetic outflow was assessed. Muscle sympathetic nerve activity (MSNA) on the right peroneal nerve, vasoactive hormones, and renal and cardiovascular responses were measured during CPPB (+12 mmHg) in 10 male subjects (22.0 +/- 0.6 yr, 66.8 +/- 1.5 kg body wt). The experiments consisted of a 1-h control, 1 h with CPPB (experimental) or without CPPB (a time control), and a 1-h recovery period. Two blood samples were taken during each period for measurements of arginine vasopressin (AVP), plasma aldosterone (PAldo), plasma renin activity (PRA), norepinephrine, and atrial natriuretic peptide (ANP), and urine was collected hourly for the measurement of urine volume and electrolytes and clearances. MSNA rapidly increased (P < 0.05) at the onset of CPPB, continued to increase during exposure, and rapidly returned to the normal level at recovery. The MSNA changes coincided with increased plasma NE and were concurrent with a reduced (P < 0.05) urine output associated with a reduction of both free water and osmolal clearances, Na+ and osmolal excretions, and creatinine clearance (glomerular filtration rate). AVP and PRA increased (P < 0.05), whereas PAldo and ANP were unchanged. The results are consistent with the concept that increased sympathetic outflow may play a role in the reduction of urinary output and Na+ excretion during unloading of the cardiopulmonary receptors.

Adult↗
PubMed1994

An infant with pseudohypoaldosteronism accompanied by cholelithiasis.

A case of an infant with very rare concurrence of pseudohypoaldosteronism and cholelithiasis is described. Aldosterone concentration was extremely high (64.6 nmol/l; normal 0.03-4.4 nmol/l) and fludrocortisone did not have favorable effects on hyperkalemia (7.4 mEq/l) and hyponatremia (124 mEq/l). A gallstone was found using ultrasonography at age 6 months, and it was extirpated surgically. The combination has not been reported previously. The study supports the previous hypothesis that cholelithiasis is found more often in infants with dehydration or electrolyte derangement.

Aldosterone↗
PubMed1994

Excessive food aversion, compulsive exercise and decreased height gain due to fear of obesity in a prepubertal girl.

A case of a 7-year-old girl with a remarkable food aversion and excessive weight reduction caused by fear of obesity, which has been demonstrated in pubertal girls with symptoms partly similar to anorexia nervosa, is reported. Although the patient's weight was reduced to the upper limits of the normal range with diet and exercise, she reduced her food intake more strictly and did not at all eat food consisting of carbohydrates. Exercise was performed longer than before. Her weight continued to decrease and height velocity lowered from 6.0 to 4.1 cm/year (mean +/- SD of the age-matched normal girls: 5.5 +/- 0.74 cm/year). Her eating behavior was normalized without specific psychotherapy for anorexia nervosa. It is suggested that food aversion with weight loss and decrease in height gain due to fear of obesity may occur in prepubertal children as well as in adolescent girls.

Anorexia Nervosa↗