Biomedical subjects

A Yoshida

Publications and source records attributed to A Yoshida.

At least 217 records · Page 12Linked to original sources

PubMed1999

Quantitative analysis of the dendritic architectures of cat hypoglossal motoneurons stained intracellularly with horseradish peroxidase.

Little is known about the dendritic architecture of cat hypoglossal motoneurons. Thus, the present study was done to provide quantitative descriptions of hypoglossal motoneurons and to determine correlations between dendritic size parameters by using the intracellular horseradish peroxidase (HRP) injection technique in the cat. Twelve hypoglossal motoneurons stained with HRP were antidromically activated by stimulation applied to the medial branch of hypoglossal nerve. Eight (type I) and four (type II) of the 12 motoneurons were located in the ventral and dorsal parts of the ventromedial subnucleus of hypoglossal nucleus, respectively. The somatodendritic morphology of the two types of neurons was remarkably different, especially in the dendritic arborization pattern. The type I neurons established an egg-shaped dendritic tree that was distributed through the nucleus to the reticular formation; the type II dendritic tree was confined within the nucleus and presented a rostrocaudally oriented, mirror-image, fan-shape appearance. The total dendritic area and length and the number of terminations and branch points were significantly larger for type I than for type II neurons. For the two types of neuron, there was a positive correlation between stem dendritic diameter and several dendritic size parameters. Although the slopes of the regression lines were slightly different between the two, these were not statistically significant. The present study provides evidence that hypoglossal motoneurons located in the ventromedial subnucleus could be divided into two types according to the dendritic arborization pattern and quantitative analysis of the dendritic tree and according to neuronal location and suggests that the two types of hypoglossal motoneurons can be viewed as intrinsically distinct cell types: type I and type II, which innervate extrinsic and intrinsic muscles, respectively. In addition, the morphometric analysis made it possible to estimate the size of the dendritic tree by measuring the stem dendritic diameter.

Animals↗

PubMed1999

A novel dnaK operon from Porphyromonas gingivalis.

The nucleotide sequence of the dnaK operon cloned from Porphyromonas gingivalis revealed that the operon does not contain homologues of either dnaJ or grpE. However, there were two genes which encode small heat shock proteins immediately downstream from the dnaK and they were transcribed together with dnaK as one unit. The ATPase activity of the P. gingivalis DnaK was synergistically stimulated up to 40-fold in the simultaneous presence of Escherichia coli DnaJ and GrpE. These results suggest that the DnaK homologue of P. gingivalis, with its unique genetic structure and evolutionary features, works as a member of the DnaK chaperone system.

Adenosine Triphosphatases↗

PubMed1999

Relationship between autofluorescence and advanced glycation end products in diabetic lenses.

Autofluorescence and advanced glycation end product (AGE) levels were measured in the lenses of 9 diabetic Chinese hamsters and 6 age-matched controls. Lens autofluorescence also was measured in 37 diabetic patients and 14 age-matched controls. Lens autofluorescence values were measured noninvasively with a lens measurement system using color filters with peak transmission at 365- and 434-nm wavelengths (excitation and emission, respectively) that are characteristic of AGE fluorescence. The peak lens autofluorescence level was used as the lens autofluorescence value, and the mean lens autofluorescence values from both eyes of each subject were used for statistical analysis. The AGE levels in one lens from each hamster were measured by noncompetitive enzyme-linked immunosorbent assay with a polyclonal anti-AGE antibody. We found a 2.2 times increase of the mean lens autofluorescence value of diabetic hamsters in comparison with that of controls (P<0.01). We also found a 1.5 times increase of the mean AGE level from the lenses of diabetic hamsters in comparison with that of controls (P<0.01). Moreover, a statistically significant positive correlation between the AGE level and autofluorescence value in the same lenses was observed in all hamsters (rho=0.58, P<0.05). In human subjects, we found a 1.4 times increase of the mean lens autofluorescence value of diabetic patients in comparison with that of age-matched controls (P<0.01). Our results suggest that non invasive measurement of lens autofluorescence may be a guide to AGE levels in lenses.

Aged↗

PubMed1999

Cyclosporin A increases tear fluid secretion via release of sensory neurotransmitters and muscarinic pathway in mice.

Cyclosporin A, an immunosuppressant, has the potential to increase tear fluid secretion through mechanisms which are not yet well understood. To gain insight into this question, we investigated the effect of cyclosporin A containing eyedrops on lacrimation in normal mice. Topical application of 0.1% cyclosporin A eyedrops for 3 days significantly increased lacrimation. This response was completely blocked by pre-exposure to 1% capsaicin. Immunohistochemical analysis revealed that capsaicin treatment depleted substance P from the lacrimal gland. Furthermore, following 1% atropine treatment, which completely blocks pilocarpine-stimulated (500 micrograms kg-1, i.p.) lacrimation, application of 0.1% cyclosporin A eyedrops significantly increased lacrimation. However, this increase was less than the response seen with 0.1% cyclosporin A in the absence of atropine. Interestingly, substance P-induced tear secretion was also partially inhibited in atropine treated mice. These results suggest that cyclosporin A accelerates tear secretion by releasing neurotransmitters from sensory nerve endings which interacts with the parasympathetic nerves.

Administration, Topical↗

PubMed1999

Apoptosis and proliferative activity in thyroid tumors.

To clarify the growth mechanisms of thyroid tumors, we examined apoptotic cells in 61 thyroid tumors, consisting of 14 adenomas, 35 papillary carcinomas, 4 follicular carcinomas, and 8 undifferentiated carcinomas, using terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate digoxigenin-nick end labeling (TUNEL). The proliferative activity was also evaluated immunohistochemically using the monoclonal antibody to Ki-67 antigen (MIB-1) in the same tumors. The apoptotic index (AI) was expressed as a percentage of the TUNEL-positive cells in the tumor cells, and a proliferation index (PI), being the percentage of Ki-67 positive cells, was calculated for each tumor. The overall level of AI was very low in all histotypes of the thyroid tumors analyzed, the mean AI being 0.5 +/- 0.4 in adenoma, 0.4 +/- 0.3 in differentiated carcinoma, and 1.8 +/- 1.5 in undifferentiated carcinoma. The PI in the thyroid tumor subtypes was significantly lower in adenoma and differentiated carcinoma, at 0.5 +/- 0.7 and 1.1 +/- 0.7, respectively, than that in undifferentiated carcinoma at 14.5 +/- 3.7 (P < 0.05). There was no correlation between clinicopathological factors and AI or PI in differentiated thyroid carcinoma. Our findings suggest that apoptosis occurs infrequently in thyroid tumors, and that proliferative activity markedly differs according to the thyroid tumor subtypes. Moreover, the ratio between proliferating cells and apoptotic cells may reflect thyroid tumor progression.

Adenocarcinoma, Follicular↗

PubMed1999

Cholesterol synthesis and degradation in normal rats fed a cholesterol-free diet with excess cystine.

Feeding a diet with excess cystine to rats resulted in hypercholesterolemia. To understand the mechanism of the hypercholesterolemia, cholesterol synthesis and degradation, bile acid content of bile, and fecal steroids were determined. The in vivo incorporation of tritiated water into hepatic cholesterol, and activity of hepatic 3-hydroxy-3-methylglutaryl-CoA reductase in rats fed a high-cystine diet were significantly higher than those in rats fed a control diet. The activity of hepatic cholesterol 7 alpha-hydroxylase was similar between two groups. Little effect of cystine supplementation was found on fecal sterol excretion although there were some changes in biliary excretion of cholic acid derivatives. These results indicate that hypercholesterolemia caused by feeding of a high-cystine diet may be due to the stimulation of hepatic cholesterol synthesis.

Animals↗

PubMed1999

Retinal detachment associated with a macular hole in severely myopic eyes.

PURPOSE: To investigate factors associated with extensive retinal detachment in severely myopic eyes with a macular hole. METHOD: Fifty-two consecutive eyes with a macular hole and severe myopia were retrospectively studied. RESULTS: An extensive retinal detachment, defined as extending beyond the cuff of subretinal fluid, was observed in 37 eyes (71%). Extensive retinal detachment developed in 36 (95%) of 38 eyes with a posterior staphyloma and in one (7%) of 14 eyes without a posterior staphyloma (P<.0001). Extensive retinal detachment also developed in 32 (89%) of 36 eyes with complete posterior vitreous detachment and in five (31%) of 16 eyes without posterior vitreous detachment (P<.0001). CONCLUSION: Posterior staphyloma rather than anteroposterior vitreomacular traction may contribute to the development of retinal detachment associated with a macular hole in severely myopic eyes.

Adult↗

PubMed1999

Phenethyl alcohol glycosides and isopentenol glycoside from fruit of Bupleurum falcatum.

Investigation on the constituents of the fruit of Bupleurum falcatum L. resulted in the isolation of the three new glycosides, phenethyl alcohol 8-O-beta-D-glucopyranosyl-(1-->2)-O-beta-D-apiofuranosyl-(1-->6)-b eta-D- glucopyranoside, phenethyl alcohol 8-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside and isopentenol 1-O-beta-D-apiofuranosyl-(1-->6)-beta-D-glucopyranoside along with five known glycosides, icariside D1, icariside F2, saikosaponin a, saikosaponin c and saikosaponin d. The structures of these compounds were elucidated on the basis of interpretation of chemical and spectral data.

Carbohydrate Conformation↗

PubMed1999

Oral fluorescein angiography with the confocal scanning laser ophthalmoscope.

OBJECTIVE: To evaluate the efficacy of oral fluorescein angiography with a confocal scanning laser ophthalmoscope (SLO) system. DESIGN: Comparative case series. PARTICIPANTS: The authors used a confocal SLO (Heidelberg Retina Angiograph [HRA]) to perform oral fluorescein angiography in 47 patients, 13 of whom were without any retinal disease and 34 with a variety of retinal diseases including macular holes and pucker, inflammatory diseases, retinal vascular diseases, and age-related macular degeneration. The images were also compared to images taken with a fundus camera after intravenous fluorescein injections in patients on whom both studies were done. INTERVENTION: Color fundus photographs were taken of each eye (30 degrees fundus camera) before drinking 4 ml of 25% sodium fluorescein mixed with 60 ml of orange juice. After oral fluorescein ingestion, images of each eye were taken with a fundus camera (TriX film) and the HRA (using 512- x 512-pixel resolution). The images were repeated at 0-, 2.5-, 5-, 7.5-, 10-, 12.5-, 15-, 20-, 25-, and 30-minute intervals. Twenty of the 47 patients underwent intravenous fluorescein angiography performed with the fundus camera. MAIN OUTCOME MEASURE: Images were analyzed by a masked reader, and foveal avascular zone visualization, branch retinal vessel identification, and image quality were scored. Statistical analysis was performed with a t test for paired data with a two-tailed test of significance (alpha = 0.05). RESULTS: Foveal avascular zone was 100% as seen in 16 eyes (47%) in the HRA machine versus 1 eye (2%) in the conventional fundus camera (P < 0.0001). The third-order branch retinal vessels were identified in 59% of eyes in the HRA versus 26% in the fundus camera group (P < 0.0001), and the image quality was considered comparable to an intravenous angiogram in 47% with the HRA versus 9% with the conventional fundus camera (P < 0.0001). CONCLUSIONS: Oral fluorescein angiography using the HRA produces sufficiently detailed images to diagnose, treat, and follow many types of retinal pathology.

Administration, Oral↗

PubMed1999

Mechanism of inhibition of the Na current by tocainide in guinea-pig isolated ventricular cells.

Tocainide blocked the Na current (I(Na)) in ventricular myocytes in either a tonic or a phasic block manner, having a higher affinity for the inactivated state (K(di) = 18 microM) than for the rested state (Kd(rest) = 606 microM). The degree of phasic block was enhanced and the onset of phasic block was faster with an increase in pulse duration as well as at less-negative holding potential (HP). The recovery-time constant from the phasic block of I(Na) induced by tocainide was independent of either the HP or the removal of fast inactivation. After removal of fast inactivation, tocainide showed the pulse-duration dependency of phasic block but not the voltage dependency. These results suggest that tocainide could bind to the inactivated-state receptor through the hydrophilic pathway and leave the receptor through the hydrophobic pathway, producing the tonic and phasic block of I(Na).

Animals↗

PubMed1999

Glucocorticoid-dependent induction of HMG-CoA reductase and malic enzyme gene expression by polychlorinated biphenyls in rat hepatocytes.

Administration of xenobiotics to rats results in hypercholesterolemia and in the induction of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and malic enzyme. To investigate the mechanism of the induction of the enzymes by xenobiotics, the effects of xenobiotics on gene expressions for HMG-CoA reductase, malic enzyme, and cytochrome P-450 in rat liver and in cultured hepatocyte were investigated. The treatment of rats with polychlorinated biphenyls (PCB) as a xenobiotic induced mRNAs for HMG-CoA reductase and malic enzyme as well as CYP2B1/2 (cytochrome P-450b/e). Other xenobiotics, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), and chloretone, also increased HMG-CoA reductase mRNA. In an investigation of diurnal rhythm of mRNA for HMG-CoA reductase, the induction by PCB was observed in a dark period. Induced expressions of HMG-CoA reductase gene and malic enzyme gene by PCB were observed in primary cultured rat hepatocytes and showed that the action of PCB on the gene expression relating to lipid metabolism was directed on hepatocytes. The induction was observed only in hepatocytes cultured on Engelbreth-Holm-Swarm sarcoma basement membrane gel (EHS-gel), not on type I collagen, which is usually used for monolayer culture of hepatocytes. The induction of CYP2B1/2 gene expression also was observed only in the cells cultured on EHS-gel. The induction of HMG-CoA reductase and malic enzyme by PCB required dexamethasone. However, the addition of dexamethasone per se to medium containing insulin did not show an inductive effect on levels of mRNA for HMG-CoA reductase and malic enzyme. From the data of diurnal variation and hepatocyte culture experiment, HMG-CoA reductase and malic enzyme are considered to be induced by PCB through the so-called "permissive effect" of glucocorticoid.

Journal Article↗

PubMed1999

Immune response against protozoal and nematodal infection in mice with underlying Schistosoma mansoni infection.

Schistosoma mansoni infection induces T helper (Th) 2-dominant immune response in mice not only to S. mansoni itself but also to other coexisting antigens. In the present study, we challenged S. mansoni-infected mice with the intestinal nematode, Strongyloides venezuelensis, and the intracellular protozoa, Leishmania major to see whether such Th2-dominant immune responses alter susceptibility of the host to other concomitant parasitic infections. The recovery of S. venezuelensis adult worms from the small intestine was significantly decreased by S. mansoni infection, and the protection to S. venezuelensis appeared to act on migrating larvae. Antibodies elicited by S. mansoni infection showed cross-binding to third-stage larvae antigen of S. venezuelensis. On the other hand, S. mansoni infection did not affect the outcome of L. major infection in both susceptible BALB/c and resistant C57BL/6 mice. Popliteal lymph node cells of BALB/c mice expressed mRNA for interleukin (IL)-10 rather than IL-4, regardless of S. mansoni infection, and those of C57BL/6 mice expressed IFN-gamma mRNA upon L. major antigen stimulation, even in S. mansoni-infected mice. Our findings suggest that Th2-dominant immune response induced by S. mansoni protects mice from intestinal helminthic infections, whereas they do not always modulate protozoal infections.

Animals↗

PubMed1999

A new metal ion interaction in the Tetrahymena ribozyme reaction revealed by double sulfur substitution.

The Tetrahymena ribozyme is a metalloenzyme that catalyzes cleavage of oligonucleotide substrates by phosphoryl transfer. Thiophilic metal ions such as Mn2+, Zn2+ or Cd2+ rescue the >10(3)-fold inhibitory effect of sulfur substitution of the 3'-oxygen leaving group but do not effectively rescue the effect of sulfur substitution of the nonbridging pro-Sp phosphoryl oxygen. We now show that the latter effect can be fully rescued by Zn2+ or Cd2+ using a phosphorodithioate substrate, in which both the 3'-oxygen and the pro-Sp oxygen are simultaneously substituted with sulfur. These results provide the first functional evidence that metallophosphotransferases can mediate catalysis via metal ion coordination to both the leaving group and a nonbridging oxygen of the scissile phosphate.

Animals↗

PubMed1999

Messenger RNA level and protein localization of transforming growth factor-beta1 in experimental tooth movement in rats.

Transforming growth factor-beta1 (TGF-beta1) is known to be associated with local bone remodeling. We hypothesize that TGF-beta1 is induced in bone and regulates adaptive alveolar bone modeling during tooth movement. To test this hypothesis, we examined the steady-state mRNA level of TGF-beta1 and the protein localization of TGF-beta1 and its type II receptor (TbetaR-II) during experimental tooth movement. Maxillary right molars, M1, M2 and M3, of rats were moved palatally for 1, 3 and 7 d by a finger coil spring anchored to the upper incisors. The contralateral side was used as a control. After 3 d of tooth movement, intense immunostaining for TGF-beta1 and TbetaR-II was observed in cuboidally shaped osteoblasts in the tension zone, and in bone-resorbing osteoclasts in the compression zone. On the control side, few active osteoblasts and osteoclasts were observed. Reverse transcriptase-competitive polymerase chain reaction revealed significant increases in TGF-beta1 mRNA in alveolar bone cells on the tooth movement side on day 3 and day 7. Taken together, our data indicate that TGF-beta1 is induced during tooth movement and we propose that this may regulate adaptive alveolar bone modeling.

Alveolar Process↗

PubMed1999

Obesity affects expression of progesterone receptors and node metastasis of mammary carcinomas in postmenopausal women without a family history.

Possible relationships between risk factors, such as obesity and a family history of breast cancer, and prognostic factors of mammary carcinomas were investigated by examining the body mass index of patients and the expression of estrogen (ER) and progesterone receptors (PgR), c-erbB-2 and p53, grade of histology, size of tumors and nodal status of mammary carcinomas. There was no significant difference in the body mass index of premenopausal patients either with or without a family history. For postmenopausal patients, the body mass index was significantly low in patients with a family history compared with patients without a family history. In premenopausal patients with or without a family history and in postmenopausal patients with a family history, there was no significant difference in the body mass index regardless of the mammary carcinoma prognostic factor, such as expression of ER, PgR, c-erbB-2 and p53, grade of histology, size of tumors and nodal status. However, in postmenopausal patients without a family history, body mass index was significantly high for patients with mammary carcinomas that had PgR expression and node metastasis. These results suggest that obesity may affect the PgR status and nodal status of mammary carcinomas in postmenopausal patients without a family history.

Body Mass Index↗

PubMed1999

Biased T cell receptor Vbeta gene expression in bronchoalveolar lavage fluid from Japanese patients with sarcoidosis.

OBJECTIVE: Sarcoidosis is believed to be one of the T cell-mediated granulomatous diseases with unknown aetiology. We attempt to search for the causative T cell clones of sarcoidosis. METHODS: We study T cell receptor beta-chain variable region (Vbeta) repertoire in peripheral blood (PB) and bronchoalveolar lavage fluid (BALF) from patients with sarcoidosis, using semi-quantitative reverse transcriptase-polymerase chain reaction method. The expression of 22 kinds of Vbeta genes is examined in 17 patients with sarcoidosis and nine normal subjects. RESULTS: Compared with control subjects, the group with sarcoidosis exhibits significantly high expressions of the Vbeta2 (P < 0.005, Wilcoxon's test) and Vbeta6 (P = 0.005) genes in BALF. In each BALF sample, the Vbeta2 (P < 0.01, chi2 test) and Vbeta6 (P < 0.01) genes were overexpressed (> 2 SD above the mean value for each Vbeta observed in control subjects) in 11 and 10 of 17 patients with sarcoidosis, respectively. Furthermore, the amino acid sequences of Vbeta6+ complementarity determining region 3 were conserved in one of three patients. There is, however, no disposition of Vbeta gene usage in PB from patients with sarcoidosis compared with control subjects. CONCLUSIONS: The T lymphocytes with Vbeta2 and/or Vbeta6 are associated with the pathogenesis of sarcoidosis. The possibility exists that these T lymphocytes might be capable of recognizing the restricted antigens, thereby inducing oligoclonal expansion.

Adult↗

PubMed1999

Metabolic characteristics of the elderly with recurrent calcium oxalate stones.

OBJECTIVE: To determine the metabolic characteristics of elderly patients with recurrent calcium oxalate stones. PATIENTS AND METHODS: Metabolic abnormalities were investigated in 88 patients with recurrent calcium oxalate stones, including 70 aged <60 years and 18 aged >/=60 years. The frequency of each metabolic abnormality and the value of each urinary constituent were compared among subgroups of age and gender. RESULTS: Hyperoxaluria was the most common abnormality, present in 56% and 67% of patients aged <60 and >/=60 years, respectively. Hyperuricosuria was significantly more common in older than in younger patients. There were no significant differences in the frequencies of hypercalciuria and hypocitraturia between the age groups. The urinary excretion of oxalate and the ratio of oxalate to creatinine were significantly greater in older than in younger men. The frequency of low urine volume was lower in older than in younger patients and the mean urinary volume was also greater in the older group. CONCLUSIONS: Hyperuricosuria and hyperoxaluria seem to be essential risk factors for calcium oxalate stone formation in elderly patients. Urinary oxalate excretion is significantly greater in older than in younger stone formers and is more prominent in men.

Adult↗

PubMed1999

Effects of amlodipine on native cardiac Na+ channels and cloned alpha-subunits of cardiac Na+ channels.

The inhibitory effects of amlodipine besilate (CAS 11470-99-6) on the native Na+ current (INa) and cloned human cardiac Na+ channel alpha subunit (hH1) were studied by whole cell patch clamp techniques. Amlodipine produced tonic block of INa in a concentration- and holding potential (HP)-dependent manner with hyperpolarization of H infinity. Amlodipine produced phasic blockade of INa, which was dependent on HP and pulse duration. Amlodipine produced tonic blockade of hH1 in a concentration-dependent manner with 1 : 1 stoichiometry, and phasic blockade of hH1 which was dependent on the pulse duration. Amlodipine blocked INa in a voltage- and frequency-dependent manner via affinity to the resting as well as inactivated conformations of the alpha subunit.

Algorithms↗