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Biomedical subjects

K Shiraki

Publications and source records attributed to K Shiraki.

At least 145 records · Page 8Linked to original sources
PubMed1997

Hypofluorescent spots in indocyanine green angiography of peau d'orange and fundus.

PURPOSE: Hypofluorescent spots were seen in indocyanine green (ICG) angiography of peau d'orange fundus in eyes with angioid streaks. Origin of the hypofluorescent spots were examined with attention to their correlation with a peau d'orange appearance of the central fundus using a computer-assisted image comparison system. METHODS: ICG angiography was performed in 5 patients having peau d'orange appearance of fundus using a scanning laser ophthalmoscope (SLO) and a digital video-fundus camera. The same central fundus areas corresponding to hypofluorescent spots in an ICG angiogram were then digitally identified in a fluorescein angiogram and in a red-free picture in all 10 eyes of the 5 patients. Monochromatic light observation was also performed with a dark field observation using an SLO to see subretinal or intrachoroidal pigment clumping. RESULTS: In no patient, the areas identified with hypofluorescent spots did show relevant changes in fluorescein angiogram or red-free picture. SLO examination revealed no perfusion defect at the same areas. The dark field observation showed no pigment clumping at the peripapillary and papillomacular bundle regions where hypofluorescent spots were seen. CONCLUSIONS: Hypofluorescent spots seen in ICG angiograms did not show exact consistency with peau d'orange changes in their location and shape. Perfusion defects or blocking by pigments were not a cause of hypofluorescent spots. The scattered hypofluorescent spots were considered to be relevant with irregular affinity of the fundus to ICG dye.

Adult↗
PubMed1997

Captopril suppresses interstitial fibrin deposition in coxsackievirus B3 myocarditis.

The effects of captopril on murine coxsackievirus B3 (CB3) myocarditis were investigated, with focus on interstitial fibrin deposition and changes in the connective tissue matrix. Captopril was administered intraperitoneally at a dose of 0.1 mg/g to CB3-infected mice daily on days 10-30 in experiment I (inflammatory phase) and on days 30-60 in experiment II (fibrotic phase). In experiment I, mouse survival was higher in the captopril-treated group than in the untreated group. Histological improvement, including prevention of extravasated fibrin deposition, maintenance of connective tissue architecture, suppression of myocyte hypertrophy, and prevention of myosin isoform shift from alpha to beta, was observed in captopril-treated mice in experiment I, but not in experiment II; in experiment II, captopril administration suppressed thickening of the interstitial reticulin fibers. Captopril inhibited inflammatory fibrin deposition, postmyocarditic myocyte hypertrophy, and ventricular remodeling during the inflammatory phase, but not during the fibrotic phase, of CB3 myocarditis in mice.

Animals↗
PubMed1997

Mechanism for changes in vasopressin during acute exposure at 3 atm abs air.

Plasma arginine vasopressin (AVP) concentration is reduced in human subjects during prolonged saturation dive exposures of 4 atmospheres absolute (atm abs) and greater. The objectives of the present study were to determine if AVP would be reduced in eight male subjects during a 1-h exposure of 3 atm abs air and, if so, to determine the mechanisms responsible for the AVP response. Assessments of transmural central venous pressure (central venous pressure-esophageal pressure) and cardiac volume measurements were made to evaluate the possible role of cardiopulmonary receptors on the AVP response. Also, plasma osmolality (P(osmol)), venous blood gases, and mean corpuscular volume (MCV) were determined to evaluate potential effects of osmoreceptor and other fluid shifts on AVP release. AVP decreased (P < 0.05) by 0.5 microU/ml at 3 atm abs, whereas the transmural central venous pressure and cardiac volume remained unchanged throughout the experimental periods. A significant reduction (P < 0.05) in P(osmol) (by approximately 3 mosmol/kgH2O) was detected at 3 atm abs. Therefore, we conclude that the reduction in P(osmol) may cause the reduction in AVP during exposure to 3 atm abs pressure. The reduction in P(osmol) without water intake requires the postulation of an internal source of water. We propose that the threefold increase (P < 0.01) in venous PO2 and concomitant decrease (P < 0.05) in venous MCV suggest that the red blood cell may contribute to hypotonicity at 3 atm abs.

Acid-Base Equilibrium↗
PubMed1997

Carotid baroreflex control of heart rate during acute exposure to simulated altitudes of 3,800 m and 4,300 m.

To examine the baroreflex response in humans during acute high-altitude exposure, the carotid baroreflex cardiac responsiveness was studied using a neck chamber in seven unacclimatized male subjects. Measurements were made in a high-altitude chamber on separate days at sea level and during 1-h exposure at two different altitudes of 3,800 m [partial pressure of oxygen in inspired air (PI(O2)) = 90 mmHg] and 4,300 m (PI(O2) = 82 mmHg). R-R intervals were plotted against neck chamber pressures, and the baroreceptor response was analyzed by applying a four-parameter sigmoidal logistic function. The baroreceptor response curve shifted downward in either altitude, reflecting a tachycardic response at high altitude, and the magnitude of the shift was greater at 4,300 m than at 3,800 m. There was no change in the sigmoidal parameters at 3,800 m compared with sea level except for a reduction (P < 0.05) of the minimum R-R interval. At 4,300 m the maximal R-R range, slope coefficient, minimum R-R interval, and maximal gain of the curve decreased significantly (P < 0.05) compared with sea level values, whereas the centering point of the curve remained unchanged. These results suggest that hypoxia (PI(O2) = 82 mmHg) reduces the sensitivity of carotid baroreflex cardiac response.

Adult↗
PubMed1997

Japanese Biliary Atresia Registry, 1989 to 1994.

The Japanese Biliary Atresia Society founded in 1980 for the aim of investigations of all aspects of biliary atresia (BA), started a nationwide registry of BA patients in 1989. A total of 626 cases were registered from 1989 to 1994. The male to female ratio was 0.58. Corrective surgery was performed in 603 patients. Regarding the type of obstruction, 63 cases were Type I, atresia of the common bile duct, 9 were Type II, atresia of the hepatic ducts, and 543 were Type III, atresia of the porta hepatis. As initial corrective procedures, original Roux-en Y, Suruga II and Roux-en Y with intestinal valve were mainly employed. Jaundice cleared in 346 patients (57%) and decreased in 131, while it persisted in 120. The 5-year-follow-up showed that 34 patients, 49% of the patients who were followed up, were alive without jaundice, while 28 (41%) are dead. Thirty five, 33% of the patients who were entered to the Registry, were lost to follow-up.

Biliary Atresia↗
PubMed1997

Effects of cholestatic agents on the structure and function of bile canaliculi in neonatal rat hepatocytes in primary culture.

The effects of cytochalasin B and colchicine on the structure and function of bile canaliculi were studied in neonatal rat hepatocytes in primary culture. Cellular contacts of neonatal hepatocytes were not as tight as those of adult hepatocytes. There was no remarkable difference in the ultrastructure of bile canaliculi between neonatal and adult hepatocytes. Neonatal hepatocytes treated with cytochalasin B were round in shape and aggregated in groups of several cells. Actin filaments stained by rhodamine-phalloidin were disrupted and condensed at the cell periphery or around dilated bile canaliculi. Markedly-dilated bile canaliculi with less microvilli were observed by transmission electron microscopy while the secretory function of horseradish peroxidase, which was used as a marker for uptake, transport and secretion into bile canaliculi, were maintained. The lumen of dilated bile canaliculi was found close to the undersurfaces of hepatocytes by scanning electron microscopy after turning over the cultured cells. By colchicine treatment, the filamentous structure of microtubules in neonatal hepatocytes disappeared. The ultrastructure of the bile canaliculi was not affected by the treatment, but transport and secretion of horseradish peroxidase into bile canaliculi were inhibited. The development of strict cellular polarity in neonatal hepatocytes may be suppressed in neonatal hepatocytes; however, cholestatic agents which rearrange the cytoskeleton caused the same morphological or functional changes of bile canaliculi as in adult hepatocytes.

Animals↗
PubMed1997

Augmentation of natural killer cell activity induced by cytomegalovirus infection in mice treated with FK506.

Comparable rates of patient and graft survival after FK506 and cyclosporine treatments have been reported in the prevention of liver allograft rejection. On this basis, we examined the effect of FK506 on pathogenesis of cytomegalovirus (CMV) infection in mice. FK506 induced apparent immunosuppression in mice which could be monitored by the level of antibody production. The effective dose of trinitrophenyl-keyhole limpet hemocyanin (TNP-KLH) for 50% reduction in antibody production was 0.9 mg/kg. Even in such an immunosuppressed status at this or higher dose of FK506, CMV infection was relatively alleviated, which was observed by the frequency of virus isolation and the mean virus titer of the lungs of mice treated with 0.1-1 mg/kg FK506 in comparison to untreated mice. The dose of FK506 attaining 50% frequency of lung infection was 1.5 mg/kg. The activity of natural killer (NK) cells was enhanced in infected mice. This enhancement was stronger in infected mice treated with FK506 at 0.32 mg/kg and 10 mg/kg than in untreated infected mice on day 3 post infection (p.i.). Thus, an immunosuppressant FK506 augmented inducible NK cell activity and alleviated MCMV infection even under immunosuppression.

Animals↗
PubMed1996

Nitric oxide and murine coxsackievirus B3 myocarditis: aggravation of myocarditis by inhibition of nitric oxide synthase.

OBJECTIVES: This study sought to investigate the effects of nitric oxide inhibition in a murine model of coxsackievirus B3 myocarditis. BACKGROUND: Little is known about the contribution of nitric oxide to the pathophysiology of myocarditis. METHODS: Antiviral activity was tested in vitro using nitric oxide inhibition by treatment with activated macrophages of NG-nitro-L-arginine methyl ester. In the in vivo experiments, NG-nitro-L-arginine methyl ester and NG-nitro-D-arginine methyl ester (both at 100 micrograms/ml) were administered to C3H/He mice early (days 0 to 14) and late (days 14 to 35) after infection with coxsackievirus B3. RESULTS: In the in vitro experiments with interferon-gamma- and lipopolysaccharide-induced activated murine macrophages, treatment with the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester, but not its inactive enantiomer NG-nitro-D-arginine methyl ester, restored coxsackievirus B3 titers. In the in vivo experiments in the early treatment group, myocardial virus titers were higher in NG-nitro-L-arginine methyl ester-treated than infected untreated animals, and both inflammatory cell infiltration and necrosis were more severe. In the late treatment group, more severe necrosis and more dense myocardial and perivascular fibrosis were observed in NG-nitro-L-arginine methyl ester-treated than in infected untreated animals. NG-Nitro-D-arginine methyl ester administration was ineffective. CONCLUSIONS: Nitric oxide inhibition increases myocardial virus titers, resulting in the aggravation of cardiac pathology in the early stage of coxsackievirus B3 myocarditis. In the late stage, it induces more severe cardiomyopathic lesions. Nitric oxide plays a defensive role in the pathogenesis of coxsackievirus B3 myocarditis.

Animals↗
PubMed1996

Cascade of fever production in mice infected with influenza virus.

The cascade of fever production in influenza was studied. To analyse fever production in a murine model, we selected DBA/2 mice that have the highest susceptibility in fibrile responses among seven mouse strains. Intranasal influenza infection- and interferon (IFN)-induced fever production was studied in this mouse model. Fever was induced prominently on day 2 after influenza infection and IFN activity was also increased in serum. Only the level of interleukin (IL)-1 alpha, an endogenous pyrogen, rose markedly in serum among cytokines (IL-1 alpha, IL-2, IFN-gamma, and tumor necrosis factor-alpha) examined. Fever was induced 14 hr after intraperitoneal IFN-alpha treatment and IL-1 alpha level rose significantly in the serum of the IFN-alpha-treated mice as compared with that of untreated mice. Fever production was significantly suppressed by treatment with anti-IFN-alpha/beta or anti-IL-1 alpha antibody in infected mice and the former significantly suppressed responsive IL-1 alpha production, indicating that elevated IFN activity induced IL-1 alpha production and subsequently fever production in infected mice. The activity of cyclooxygenase (COX) that produces prostaglandin (PG)E2 was significantly augmented in the brain of infected mice on day 2 after infection. Fever production was suppressed by the inhibition of COX activity with aspirin, although IL-1 alpha level was maintained at the elevated level. Therefore, influenza infection in mice turned on the following cascade for fever induction: IFN production, IL-1 alpha production, elevated COX activity, and PGE2 production. We elucidated the relationship among IFN activity, IL-1 alpha production and COX activity and demonstrated the cascade of fever production in influenza infection.

Animals↗
PubMed1996

Prophylactic treatment of cytomegalovirus infection with traditional herbs.

Hot water extracts of four traditional herbs, Geum japonicum, Syzygium aromaticum, Terminalia chebula and Rhus javanica, which have been shown to have anti-herpes simplex virus (HSV) activity in vivo, were examined for anti-cytomegalovirus (CMV) activity in vitro and in vivo in this study. They inhibited replication of human CMV and murine CMV (MCMV) in vitro. These anti-CMV activities in vivo were examined in an MCMV infection model using immunosuppressed mice. Mice were subcutaneously treated with various doses of cyclosporine, and immunosuppression and MCMV infection were monitored by suppression of antibody production and virus yield in the lung, respectively. Each herbal extract was orally administered to mice treated with 50 mg/kg of cyclosporine from a day before intraperitoneal infection, and the efficacy of herbs was evaluated by the reduction in the virus yield in the lung. Among them Geum japonicum, Syzygium aromaticum, and Terminalia chebula significantly suppressed MCMV yields in lungs of treated mice compared with water treatment. Efficacy of oral treatment with 750 mg/kg per day of Geum japonicum extract was similar to that of the intraperitoneal administration of 2 mg/kg per day of ganciclovir in increasing the body weight of infected mice and reducing the virus yield in the lungs. These herbs may be beneficial for the prophylaxis of CMV diseases in immunocompromised patients.

Animals↗
PubMed1996

Therapeutic basis of glycyrrhizin on chronic hepatitis B.

Glycyrrhizin, a major component of a herb (licorice), has been intravenously used for the treatment of chronic hepatitis B in Japan and improves liver function with occasional complete recovery from hepatitis. This substance modifies the intracellular transport and suppresses sialylation of hepatitis B virus (HBV) surface antigen (HBsAg) in vitro. This study was designed to clarify the pharmacological basis for its effectiveness. The structure-bioactivity relationship of glycyrrhizin, glycyrrhetic acid 3-O-monoglucuronide and glycyrrhetic acid was determined, and glycyrrhetic acid was found to be the most active of them. The amounts of three substances bound to the liver were evaluated in guinea pigs after intravenous administration of glycyrrhizin. Glycyrrhizin and glycyrrhetic acid 3-O-monoglucuronide were detected at concentrations of 31.8-1.3 micrograms/g of liver, but glycyrrhetic acid was not detected. When glycyrrhizin attained these concentrations in the cellular fraction of the PLC/PRF/5 cell culture, it suppressed the secretion of HBsAg as reported previously. These results indicated that glycyrrhizin administered intravenously might bind to hepatocytes at the concentration at which glycyrrhizin could modify the expression of HBV-related antigens on the hepatocytes and suppress sialylation of HBsAg.

Animals↗
PubMed1996

Topical treatment of cutaneous herpes simplex virus-1 infection in mice with a specially formulated caffeine gel (Cafon).

Caffeine, although not a nucleoside analog, is known to inhibit the replication of herpes simplex virus-1 (HSV-1) and has been shown to significantly limit the spread of HSV infection in vitro. The therapeutic efficacy of caffeine was examined in a murine cutaneous infection model. The midflanks of 6-week-old BALB/c mice were infected with HSV cutaneously after application of 10% caffeine (Cafon) gel, and was reapplied to the midflank 5 times daily thereafter. Treatment with Cafon gel significantly retarded the development of skin lesions. Both midflanks were cutaneously infected, and a placebo and active gel were applied to the right and left midflanks respectively. Cafon gel significantly retarded the appearance of vesiculation and reduced the number of vesicles compared with the placebo gel. Cafon gel was as effective as 5% acyclovir ointment, and no significant difference was observed in the development of local lesions between these two topical preparations. The efficacy of Cafon gel also corresponded to that of oral treatment with 5 mg/kg or more of acyclovir in our cutaneous infection system. These results suggest that Cafon gel can be useful for the topical treatment of cutaneous HSV infection.

Acyclovir↗
PubMed1996

Efficacy of Cafon gel on cutaneous infection with herpes simplex virus (HSV)-2 and acyclovir-resistant HSV in mice.

Caffeine is known to inhibit replication of herpes simplex virus (HSV)-1 and the therapeutic efficacy of caffeine (Cafon) gel has been shown in a mouse model cutaneously infected with HSV-1. In this study we examined the inhibitory effect of caffeine on infection with HSV-2 and acyclovir-resistant HSV-1 strains, thymidine kinase (TK)-deficient and phosphonoacetic acid (PAA)-resistant HSV-1 in vitro and in vivo. Caffeine inhibited plaque formation of HSV-2 and acyclovir-resistant HSV-1 strains and their EC50 values ranged from 0.42 to 1.11 mg/ml. Topical treatment with Cafon gel was significantly effective in retarding the development of skin lesions caused by cutaneous infection with HSV-2 and PAA-resistant HSV-1 and in reducing the virus yield of the skin infected with TK-deficient HSV-1. The results suggested that Cafon gel would be useful for the topical treatment of cutaneous infection with HSV-2 and acyclovir-resistant HSV strains.

Acyclovir↗
PubMed1996

Three brothers with progressive hepatic dysfunction and severe hepatic steatosis due to a patent ductus venosus.

Three Japanese brothers with progressive deterioration of hepatic function and fatty degeneration of the liver eventually leading to hepatic encephalopathy were recently encountered. Each of them had a congenital intrahepatic portosystemic venous shunt due to a patent ductus venosus. Liver dysfunction and hepatic steatosis reverted to normal with surgical correction of the ductus venosus. Our observations suggest that impairment of liver function occurs first in the presence of malnutrition related to a reduction of blood in the portal vein. Hepatic steatosis is a consequence of a depleted metabolism of hepatocytes. Congenital portosystemic venous shunt due to a patent ductus venosus in this family has a genetic background.

Angiography↗
PubMed1996

Partial monosomy 10q and partial trisomy 9q with anal atresia due to maternal translocation: t(9;10)(q32;q26).

We report a case of a boy with a partial deletion of the long arm of chromosome 10 and partial duplication of the long arm of chromosome 9 due to maternal balanced translocation. The karyotype was 46,XY,-10, +der(10)t(9;10)(q32;q26)mat. Our patient had imperforate anus and as this finding is usually not observed in association with trisomy 9q, it suggests that partial monosomy of the long arm of chromosome 10 might be associated with anogenital anomalies.

Abnormalities, Multiple↗
PubMed1996

Maternal perception of children's weight in relation to eating disorders.

Abnormal perception of body weight in girls has been reported previously (1), and distorted perception of body shape is cited as one of the pathogenetic factors in eating disorders such as anorexia and bulimia nervosa (2,3). Parent-child relationships should also be considered as one of the factors possibly contributing to the onset of the eating disorders (3,4). In the present paper we shall examine whether mothers perceive the weight of their sons and daughters correctly or not, and we shall also compare the results with the perceptions of the children themselves, which we have reported previously in this journal (1). Five outline drawings (-20% to 20% overweight), used in the previous study (1), were shown to the mothers, who were asked to select the drawings which they considered to represent the body weight of their sons (n = 130) and daughters (n = 125), who were aged 6 to 18 years. The mean body weights of the boys and girls in the study sample were 6.0% and 6.6% overweight, respectively. The mothers perceived the weight of their sons to be significantly (P < 0.01) less than the actual weight of these boys. The mean difference between the perceived weight and the actual weight was 10.4%. The mothers' perception of their daughters' weight was also 7.9% less than the actual weight (P < 0.05) (Fig. 1).

Adolescent↗
PubMed1996

Assay for antiviral activity of herbal extracts using their absorbed sera.

We evaluated an antiviral assay procedure using serum obtained from guinea pigs administered 32 herbal extracts. In this assay, 21 of the 32 showed anti-herpes simplex virus type 1 (HSV-1) activity in serum. Ten of the 21 exhibited therapeutic anti-HSV-1 activity, and this was consistent with our previous results that 12 of the 32 were effective in murine infection models. Therefore, the serum pharmacological assay procedure was suitable for the selection of possible herbal extracts with biological activity in vivo as a pre-screening method before animal experiments.

Animals↗