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Biomedical subjects

Y Okuda

Publications and source records attributed to Y Okuda.

At least 487 records · Page 27Linked to original sources
PubMedDate not supplied

Addition of clonidine increases duration and magnitude of vasodilative effect induced by sympathetic block with mepivacaine in dogs.

BACKGROUND AND OBJECTIVES: The aim of this study is to examine the duration and magnitude of vasodilative effect induced by sympathetic block with the addition of clonidine to mepivacaine. METHODS: We measured mean arterial pressure (MAP), heart rate (HR), and right and left brachial artery blood flow (BABF) before and after stellate ganglion block (SGB) in dogs. The experimental protocol was designed as follows: (1) left SGB using 1.0 mL 0.5% mepivacaine (n = 6) and (2) left SGB using the addition of clonidine 0.5 microg to 1.0 mL 0.5% mepivacaine (n = 6). RESULTS: MAP and HR did not change significantly throughout the study in either group. Left SGB with mepivacaine increased left BABF significantly from 10 minutes through 50 minutes after SGB (baseline, 100%; peak at 10 minutes after SGB, 176% +/- 28%; P <.01). Left SGB with the addition of clonidine to mepivacaine induced a significant increase of left BABF from 10 minutes through 70 minutes after SGB (baseline, 100%; peak at 10 minutes after SGB, 223% +/- 42%; P <.01). The values of left BABF after SGB with the addition of clonidine to mepivacaine were significantly higher than those of SGB with mepivacaine alone from 10 minutes through 80 minutes after SGB (P <.05). Right BABF decreased significantly after SGB throughout the study in both groups. CONCLUSIONS: The addition of clonidine increases both duration and magnitude of the vasodilative effect induced by sympathetic block over that caused by mepivacaine alone.

Adrenergic alpha-Agonists↗
PubMedDate not supplied

Assessment of QT interval and QT dispersion following stellate ganglion block using computerized measurements.

BACKGROUND AND OBJECTIVES: Prolongation of QT interval and QT dispersion (QTD) may be associated with an increased risk of arrhythmias. This study was designed to investigate the effects of right or left stellate ganglion block (SGB) on RR interval, QT interval, the rate-corrected QT (QTc) interval, QTD and the rate-corrected QTD (QTcD) using computerized measurements. METHODS: Ten healthy volunteers underwent both right and left SGBs using 7 mL 1% mepivacaine with a 7-day interval between the 2 blocks. The measurement from the 12-lead electrocardiogram was performed for 60 minutes after SGB. RESULTS: Right SGB induced a significant decrease of RR interval immediately after the block, and significant increases of QT interval, QTc interval, QTD, and QTcD from immediately through 50 minutes after the block (P <.01). Left SGB induced a significant decrease of RR interval, and significant increases of QTc interval and QTD immediately after the block (P <.01). Left SGB also produced a significant decrease of QT interval from 20 through 50 minutes after the block, and a significant decrease of QTc interval from 30 through 50 minutes after the block (P <.05). CONCLUSIONS: Right SGB induces increases of the QT interval, QTc interval, QTD, and QTcD, and left SGB induces decreases of the QT interval and QTc interval.

Adult↗
PubMedDate not supplied

Inhibition of steroidogenesis in Leydig cells by exogenous nitric oxide occurs independently of steroidogenic acute regulatory protein (star) mRNA.

Nitric oxide (NO) plays multiple roles in the reproductive system. The authors studied the effect of NO on LH-stimulated steroidogenesis in primary cultures of rat Leydig cells, particularly seeking a link between inhibition of steroidogenesis and changes in expression of steroidogenic acute regulatory protein (StAR). Sodium nitroprusside (SNP), an NO generator, did not alter basal testosterone, but dose-dependently reduced testosterone production in the Leydig cells stimulated by LH (100 ng/mL) at 3 h after addition of SNP. Induction of StAR mRNA transcripts could be detected as early as 1 h after the addition of LH, but no effect was detected of SNP on LH induction of StAR mRNA. StAR, then, is not affected in the inhibition by NO of LH-stimulated steroidogenesis in Leydig cells.

Animals↗
PubMedDate not supplied

Sertoli cells inhibited apoptosis of pachytene spermatocytes and round spermatids.

Apoptosis in the testis represents an important physiological mechanism that regulates the number of germ cells in the seminiferous epithelium. This apoptosis is believed to be regulated by many factors, including growth factors and cytokines, which appear to suppress apoptosis of the germ cells. In this study, we examined the roles of Sertoli cells on the regulation of pachytene spermatocyte (PS) and round spermatid (RSd) apoptosis with either a co-culture trans-well system or a direct contact system. Apoptosis was detected by low molecular weight DNA fragmentation assay, in situ end labeling, and an LDH assay. In addition, the level of Bcl-2, Bax, and ICE mRNAs in PS and RSd by Northern blot analysis. When PS and RSd were cultured with Sertoli cells in either a trans-well system or direct contact system, the extent of apoptotic DNA fragmentation and LDH level were both significantly lower than those control values. TUNEL staining also revealed the inhibition of apoptosis of PS and RSd when they were cultured with Sertoli cells compared with controls (p <0.05). Moreover, the extent of apoptotic DNA fragmentation and LDH level were significantly lower in the direct contact system than in the trans-well system. TUNEL staining also demonstrated a more decrease in apoptosis of PS and RSd in the direct contact system compared with the trans-well system (p < 0.05). PS and RSd cultured with Sertoli cells exhibited an increase in Bcl-2 mRNA, whereas those cultured with serum-free medium did not show any change. The levels of Bax and ICE mRNAs decreased in PS and RSd cultured with Sertoli cells in comparison with control values. These results suggest that Sertoli cells can prevent apoptosis of germ cells, and that the effect of Sertoli cells on germ cells is mediated by cell to cell interaction or, remote effects of inhibitory factors on apoptosis.

Animals↗
PubMedDate not supplied

CT demonstration of portal vein remnant within metastatic liver tumor.

We describe a patient with a metastatic liver tumor that showed a cordlike shadow traversing the tumor on CT. Histopathologically, this cordlike shadow within the metastatic liver tumor was proved to be an infiltrated portal vein without blood flow surrounded by fibrous tissue. Vascular structures traversing a focal lesion may be seen not only in focal fatty infiltration or lymphoma but also in metastatic liver tumor.

Adenocarcinoma↗
PubMedDate not supplied

MR assessment of normal brain development in neonates and infants: comparative study of T1- and diffusion-weighted images.

PURPOSE: This study was designed to compare the sensitivity of T1- and diffusion-weighted images for the assessment of brain maturation in human brains. METHODS: T1- and diffusion-weighted images were obtained in 32 children without neurological abnormalities or growth retardation. The ages at which signal intensity changes of white matter on T1-weighted images and diffusional anisotropy appeared were compared. RESULTS: In the optic radiation, diffusional anisotropy was observed in neonates < 1 month old, whereas signal intensity became high after 1 month old. In the frontal lobe, diffusional anisotropy began to appear after 1 month of age, but signal intensity became high after 6 months of age. These visual findings were confirmed statistically by quantitative analysis using signal intensity ratios and anisotropic ratios. Similar findings were observed in the external capsule and the genu of the corpus callosum. CONCLUSION: In conclusion, diffusional anisotropy is a sensitive indicator of brain maturation in neonates and infants and precedes signal intensity change on T1-weighted images.

Brain↗
PubMedDate not supplied

Effect of hepatocyte volume on energy status in the cirrhotic rat liver.

To evaluate the effect of reduced hepatocyte volume on liver energy status, the relationship between the morphologically quantified hepatocyte volume and biochemical parameters, and the difference in nuclear density between the parenchyma and stroma were assessed in rat livers with thioacetamide-induced cirrhosis. The ratio of hepatocytes to whole liver tissue, defined as the 'hepatocyte area ratio', and the nuclear densities of the parenchyma and stroma were calculated microscopically with an image analysing system. Adenine nucleotide, protein and DNA contents, and the ornithine carbamoyltransferase activity in the liver were assayed. In the cirrhotic group, adenine nucleotide content, protein content and ornithine carbamoyltransferase activity were positively correlated with the hepatocyte area ratio, whereas DNA content was negatively correlated with this ratio. The adenylate energy charge of the cirrhotic liver was maintained at a constant level regardless of the ratio. Adenine nucleotide content, protein content and ornithine carbamoyltransferase activity per fractional 'hepatocyte area ratio' in cirrhotic livers were significantly lower than in control livers. The nuclear density of the stroma was significantly greater than that of the parenchyma. These results suggest that the lowered energy status in the cirrhotic liver is not caused by reduced hepatocyte volume but rather by impaired hepatocyte metabolism. In addition, the morphological measurement with an image analysing system was found to be useful for evaluating the effects of decreased hepatocyte volume on biochemical derangements in cirrhotic tissue.

Adenine Nucleotides↗
PubMedDate not supplied

The influence of node-fibril morphology on healing of high-porosity expanded polytetrafluoroethylene grafts.

PURPOSE: To manufacture high-porosity expanded polytetrafluoroethylene (ePTFE) vascular grafts with the same internodal distance but different node-fibril morphology, and to evaluate their biologic behaviors in a canine carotid artery implantation model. MATERIALS AND METHODS: Several types of high-porosity ePTFE vascular grafts with the same inside diameter (4 mm) and wall thickness (650 microm) were manufactured under different heating, stretching conditions. The luminal surface and cross section of the grafts were photographed by scanning electron microscopy and the node-fibril structure was examined. Two typical types of high-porosity ePTFE vascular grafts were then selected and proceeded to an animal study. The test grafts were explanted after an interval of 12 weeks and subjected to histomorphometric analyses. RESULTS: The following two types of high-porosity ePTFE vascular grafts were selected; one had a through-pore structure extending from the outer to the inner surface and the other had a random-node architecture with tortuous path channels extending from the outer to the inner surface. The histomorphometric analyses of thrombus-free surface, thickness of pseudointima, cellular ingrowth, capillary ingrowth, and cellular proliferation revealed no significant differences between the grafts. CONCLUSION: In high-porosity ePTFE vascular grafts, graft healing enhanced by transmural tissue ingrowth may be not largely dependent on node-fibril morphology. This knowledge will be helpful to design a new type of high-porosity ePTFE vascular grafts available for clinical use.

Animals↗
PubMedDate not supplied

Factors affecting A-aDo2 after open-heart surgery.

Intrapulmonary shunt, cardiac output, and O2 consumption as factors contributing to alveolar-arterial O2 tension difference (A-aDo2) were tested in 11 patients after open-heart surgery. A-aDo2 was well correlated with intrapulmonary shunt, as expected, but no correlation was found between cardiac index (CI) and intrapulmonary shunt. When total shunt (venous admixture) was above 11%, there was an inverse correlation between A-aDo2 and CI, and it was observed that CI falling below 2.5 L/min/sq m contributed significantly to the enlargement of A-aDo2. Low Pao2 (less than 65 torr, breathing air) was characterized by larger arterial-mixed venous O2 content difference than high Pao2 (is greater than 65 torr, on room air), indicating that A-aDo2 was influenced by cardiac output relative to metabolic demand. Intrapulmonary shunt played a main role in increasing A-aDo2 after open-heart surgery, and systemic factors, including changes in cardiac output and O2 consumption, also contributed to development of hypoxia.

Adolescent↗
PubMedDate not supplied

Experimental infection of specific-pathogen-free chickens with serotype-1 fowl adenovirus isolated from a broiler chicken with gizzard erosions.

Gizzard lesions were formed in specific-pathogen-free (SPF) white leghorn chickens inoculated with fowl adenovirus (FAV). The virus, serotype 1 FAV 99ZH strain (FAV-99ZH), was originally isolated from the gizzard mucosa of commercial broiler chickens exhibiting gizzard erosion with intranuclear inclusion bodies. Five-day-old and 53-day-old SPF white leghorn chickens were inoculated with FAV-99ZH by both oral and ocular routes and then examined at necropsy on days 3, 5, 7, 10, 14, and 21 postinoculation (PI). There were no clinical signs in any of the chickens after the inoculation. Focal gizzard lesions occurred macroscopically, however, in inoculated chickens at several experimental periods. FAV was recovered from tissue samples of the proventriculus, gizzard, pancreas, and rectum by day 10 or 7 PI but was not recovered from liver samples of any of the chickens. These results indicate that FAV isolated from gizzard erosion is able to reproduce gizzard lesions as necrosis and erosion in SPF white leghorn chickens and that it may have a greater degree of tissue tropism in gizzards and other digestive organs than in the liver.

Adenoviridae Infections↗
PubMedDate not supplied

Epizootic outbreaks of gizzard erosion associated with adenovirus infection in chickens.

Two outbreaks of gizzard erosion in slaughtered broiler chickens in Japan were examined pathologically and microbiologically. The prevalences of such lesions were 9%-11% and 4%-50% in the affected flocks. Affected chickens had no clinical signs. Group I fowl adenovirus (FAV) serotype 1 was isolated from gizzard lesions. Histologically, gizzard mucosa were necrotic. Intranuclear inclusion bodies were seen in the enlarged nuclei of degenerating epithelial cells of the gizzard. The keratinoid layer in the erosion was edematous and desquamated and contained degenerative cells. Moderate to marked inflammatory cell infiltration was observed in the lamina propria and perivascular connective tissue in the submucosa and muscle layer. Immunohistochemical staining showed evidence of FAV antigens in the intranuclear inclusion bodies within degenerating epithelial cells. Ultrastructurally, numerous viral particles were demonstrated in the inclusions.

Adenoviridae Infections↗
PubMedDate not supplied

Pathogenicity of serotype 1 fowl adenovirus in commercial broiler chickens.

The pathogenicity of a serotype 1 fowl adenovirus (FAV-99ZH), isolated from broiler chickens exhibiting gizzard erosion, was investigated in commercial broiler chickens. Five-, 3-, and 1-wk-old commercial broiler chickens were inoculated with FAV-99ZH by both oral and ocular routes. In the 5-wk-old chickens (trial 1), none of which had the maternal antibody to FAV-99ZH, severe gizzard erosions were observed on days 5, 7, and 10 postinoculation (PI). Among the 3-wk-old chickens (trial 2), which were separated into a control group and three treatment groups according to their maternal antibody titer levels, some chickens showed clinical signs such as depression and anorexia. Compared with the control group, all the treatment groups showed decreased weight gain. One treatment group, moreover, showed significantly decreased (P < 0.05) weight gain on day 10 PI. Severe gizzard lesions, such as erosion or ulcers, were observed from day 4 PI in all treatment groups regardless of their maternal antibody levels. The 1-wk-old chickens (trial 3) were separated into a control group and two treatment groups according to their titer levels of the inoculated virus. In spite of high maternal antibody levels, severe gizzard lesions were observed in both treatment groups, which also showed decreased weight gain. One treatment group, inoculated with the higher dose, showed significantly decreased (P < 0.05) weight gain on days 10 and 14 PI compared with the control group. Fowl adenovirus was recovered mainly from gizzard and rectal (including feces) samples from inoculated chickens but was not recovered from liver samples in any of the trials or in any of the control chickens. Although the reproduced disease was similar to that described in a previous report of experimental infection of specific-pathogen-free (SPF) white leghorn chickens with fowl adenovirus, the pathogenicity of FAV-99ZH in commercial broiler chickens was more severe than that in the SPF white leghorn chickens. The results of the present study indicate that FAV-99ZH isolated from gizzard erosion had pathogenicity and produced severe lesions in the gizzards of broiler chickens and that FAV-99ZH could infect and produce illness in broiler chickens with maternal antibodies against this virus.

Adenoviridae Infections↗
PubMedDate not supplied

Outbreaks of adenoviral gizzard erosion in slaughtered broiler chickens in Japan.

Gizzard erosion in broiler chickens was investigated at 18 slaughterhouses in Japan. The condition was observed in 13 of them, and adenoviral gizzard erosion (AGE) was diagnosed histologically, immunohistochemically and virologically in the eroded gizzards from nine of these 13. The antigen-positive intranuclear inclusion body of group 1 fowl adenovirus was observed in the epithelial cells of the affected gizzards, and fowl adenoviruses were isolated from the lesions. In two of the slaughterhouses the total weights of the gizzards disposed of in three years were 3590 kg (0.40 per cent of the gizzards inspected) and 2880 kg (0.19 per cent). Sixteen of the 19 outbreaks of gizzard erosion on 15 farms that were confirmed in three of the slaughterhouses, including the previous two slaughterhouses, were diagnosed as AGE, and the condition was suspected in the other three outbreaks. Most of the adenoviruses isolated were identified as serotype-1 by PCR-restriction fragment length polymorphism. No apparent clinical signs were observed in any of the affected flocks.

Abattoirs↗