Search PubMed⌕ Search

Biomedical subjects

Y Hara

Publications and source records attributed to Y Hara.

At least 271 records · Page 15Linked to original sources
PubMed1997

Effect of tea flavonoid supplementation on the susceptibility of low-density lipoprotein to oxidative modification.

Dietary flavonoid intake has been reported to be inversely associated with the incidence of coronary artery disease. To clarify the possible role of tea flavonoids in the prevention of atherosclerosis, we investigated the effects of tea flavonoids on the susceptibility of low-density lipoprotein (LDL) to oxidative modification. In an in vitro study, catechins or theaflavins (25-400 mumol/L) were added to plasma and incubated for 3 h at 37 degrees C. Then, the LDL fraction was separated by ultracentrifugation. The oxidizability of LDL was estimated by measuring conjugated diene, thiobarbituric acid-reactive substances (TBARS), and lipid peroxides after cupric sulfate was added. TBARS and lipid peroxides in the supernates were also measured after incubation with macrophages. Catechins significantly (P < 0.01 by ANOVA) and dose-dependently prolonged the lag time before initiation of oxidation. Among the catechins, epigallocatechin gallate exerted the most marked effect, prolonging the oxidation lag time more than vitamin E at the same molar concentration. Theaflavins exerted stronger inhibitory effects than catechins. Macrophage-mediated LDL oxidation was also inhibited by adding these tea flavonoids to the plasma samples. In an in vivo study, 14 healthy volunteers consumed 750 mL black tea/d for 4 wk. After the subjects had consumed tea for 4 wk, the lag time before LDL oxidation was significantly (P < 0.01) prolonged from 54 to 62 min. This minor prolongation occurred despite much lower plasma flavonoids than were used in vitro. No significant change was observed in eight control volunteers. LDL exposed to tea flavonoids in vitro or in vivo reduced oxidizability. We speculate that tea flavonoids may have a role in ameliorating atherosclerosis.

Adult↗
PubMed1997

Generalized CNS disease and massive GM1-ganglioside accumulation in mice defective in lysosomal acid beta-galactosidase.

Human GM1-gangliosidosis is caused by a genetic deficiency of lysosomal acid beta-galactosidase (beta-gal). The disease manifests itself either as an infantile, juvenile or adult form and is primarily a neurological disorder with progressive brain dysfunction. A mouse model lacking a functional beta-gal gene has been generated by homologous recombination and embryonic stem cell technology. Tissues from affected mice are devoid of beta-gal mRNA and totally deficient in GM1-ganglioside-hydrolyzing capacity. Storage material was already conspicuous in the brain at 3 weeks. By 5 weeks, extensive storage of periodic acid Schiff-positive material was observed in neurons throughout the brain and spinal cord. Consistent with the neuropathology, abnormal accumulation of GM1-ganglioside in the brain progressed from twice to almost five times the normal amount during the period from 3 weeks to 3.5 months. Despite the accumulation of brain GM1-ganglioside at the level equal to or exceeding that seen in gravely ill human patients, these mice show no overt clinical phenotype up to 4-5 months. However, tremor, ataxia and abnormal gait become apparent in older mice. Thus, the beta-gal-deficient mice appear to mimic closely the pathological, biochemical and clinical abnormalities of the human disease.

Animals↗
PubMed1997

Use of a split bone graft to correct the cosmetic deformity associated with the transpetrosal-transtentorial surgical approach: technical report.

OBJECTIVE: Split bone graft reconstruction was performed after a standard transpetrosal-transtentorial approach to correct the cosmetic deformity in 18 patients. TECHNIQUE: The split bone graft was made by dividing the inner table of the temporosuboccipital bone graft and covered the bone effect created by petrosectomy and mastoidectomy. The split bone graft was created and shaped during closure of the dura, so that the operation was not prolonged. RESULTS: This technique produced excellent cosmetic results immediately after surgery; the results were maintained during the follow-up period of between 20 and 46 months. No complication associated with this technique was recognized. CONCLUSION: Split bone graft reconstruction is a simple and safe technique for preventing the cosmetic deformity associated with a transpetrosal-transtentorial approach.

Bone Transplantation↗
PubMed1997

Two unusual cases of multiple dural arteriovenous fistulas.

OBJECTIVE AND IMPORTANCE: Two patients with dural arteriovenous fistulas involving the transverse sinus and superior sagittal sinus are described, with a focus on the unique type of venous drainage of the fistula. CLINICAL PRESENTATION: Both patients presented with papilledema and progressive visual disturbance. Angiography and magnetic resonance imaging showed that the fistulas involving the superior sagittal sinus had a dilated venous channel, separate from the sinus lumen, located within the wall of the sinus. INTERVENTION: Transvenous embolization of the venous channel of the fistula, proximal to its drainage into the superior sagittal sinus, resulted in closure of the fistula and restoration of the superior sagittal sinus function. The clinical symptoms were reversed; the symptoms are believed to have reflected venous hypertension in the superior sagittal sinus, resulting from the shunted flow and interfering with normal venous drainage. CONCLUSION: This unique type of dural arteriovenous fistula may be a variant, occurring in the developmental process of the fistula. It is significant clinically because transvenous embolization can be used to close the fistula and restore sinus function.

Aged↗
PubMed1997

Effect of green tea catechins on the amount of 8-hydroxydeoxyguanosine (8-OHdG) in pancreatic and hepatic DNA after a single administration of N-nitrosobis(2-oxopropyl)amine (BOP).

Effects of green tea catechins on N-nitrosobis(2-oxopropyl)amine (BOP)-induced oxidative stress in pancreas and liver were examined. Hamsters were divided into two groups: one group was given free access to a 0.1% solution of green tea catechins as drinking water (c-ham) and the other to plain tap water (w-ham) for 1 week before subcutaneous injection of BOP 20 mg/kg body weight. Zero, 1, 2, 6, 12, 24, and 48 h after BOP injection, the pancreas and liver were excised and the tissue concentration of lipid peroxides (TBA values) and the amount of 8-hydroxydeoxyguanosine (8-OHdG) in nuclear DNA were measured. The concentration of lipid peroxides and the amount of 8-OHdG in the pancreas showed similar patterns of change between c- and w-ham. Soon after BOP injection, the concentration of lipid peroxides and the amount of 8-OHdG increased with a peak at 1 and 6 h, respectively. Their peak values of c-ham were significantly depressed compared with those of w-ham. Both levels returned to steady-state levels by 24 h. In the liver, the concentration of lipid peroxides and the amount of 8-OHdG were not affected by BOP administration. These results suggest that BOP induces oxidative damages in the target organ and oral intake of green tea catechins has a protective effect on the oxidative stress.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1997

Histochemical study of the influence of transplanted teeth with periodontal ligament of the binding of peanut agglutinin in rat dorsal skin.

Our previous study showed that the expression of carbohydrate residues in junctional epithelium (JE) after resection is closely related to attachment and stratification along the dental root surface. However, the influence of the periodontal ligament on carbohydrate expression has still not been clarified. In this study we examined the relationship between the presence of periodontal ligament and the expression of carbohydrate residues on epithelium regenerating along root surfaces. We transplanted extracted rat molars with or without periodontal ligament tissue, repeatedly frozen and thawed teeth with ligament and demineralized teeth without ligament into the dorsal skin of rats. After 2, 3, 5, 7, 10, 14 or 21 d, dorsal cutaneous tissues containing transplanted teeth were resected, fixed, decalcified and embedded in paraffin. Serial sections were stained histochemically with the HRP-conjugated lectin, peanut agglutinin (PNA) to observe the expression of carbohydrate residues in regenerating epithelium. Histochemical observation revealed that lectin binding reactions were changed from the characteristics of skin to those of JE when the regenerating epithelium was attached and stratified along the tooth with unfrozen or frozen tissue. These results suggested that the structural formation and expression of PNA in regenerating epithelium around the root surface were influenced by not only the tooth but also by the periodontal ligament.

Animals↗
PubMed1997

Immunohistochemical study of cathepsin G and medullasin in inflamed gingival tissues from periodontal patients.

Cathepsin G and medullasin are 2 major serine proteinases associated with the granular fraction of polymorphonuclear leukocytes (PMNs). To know their possible involvement in the pathophysiological gingival connective tissue turnover, we have determined the distribution and localization of these 2 enzymes in inflamed gingival tissues from periodontal patients by immunohistochemistry with discriminating antibodies specific for each enzyme. The gingival connective tissues were obtained from periodontitis patients with various inflammatory conditions and control healthy subjects without any clinical signs of periodontal inflammation. In all gingival specimens examined, cathepsin G and medullasin were found mainly in neutrophil-like cells and partly in macrophage-like cells. No positive staining for both enzymes was obtained in endothelial cells and fibroblasts in every part of the gingival tissues. Immunoreactivity for each enzyme in the gingival tissues from the periodontitis group was stronger and greater in the intensity and frequency than that from the control group and appeared to be increased with the severity of the disease In both groups, the number of immunoreactive cells for each enzyme was greater in the vicinity of pocket epithelium (zone I) than in the area of central connective tissue (zone II) or the area subjacent to the oral epithelium (zone III). While both enzymes in zones II and III were exclusively found in coarse granules, their stainings in zone I were not only coarse but also diffuse. These results strongly suggest that both enzymes may have some association with inflamed gingival tissue degradation.

Adult↗
PubMed1997

Secretion of IL-1 beta, TNF-alpha, IL-8 and IL-1ra by human polymorphonuclear leukocytes in response to lipopolysaccharides from periodontopathic bacteria.

Polymorphonuclear leukocytes (PMN) are the first cells that migrate into periodontal tissues and gingival crevices in response to invading pathogens. It was recently demonstrated that PMN have the ability to synthesize and release cytokines following appropriate stimulation, while it is not clear whether these capacities are directly related to periodontal destructive processes. We therefore investigated the amounts of the cytokines interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), IL-8 and IL-1 receptor antagonist (IL-1ra) secreted by PMN from healthy donors following stimulation with lipopolysaccharide (LPS) from 4 periodontopathic bacteria, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Capnocytophaga ochracea and Fusobacterium nucleatum, and the non-oral bacterium Escherichia coli. A actinomycetemcomitans, F. nucleatum and E. coli LPS stimulated the release of significantly greater amounts of IL-1 beta, TNF-alpha and IL-8 than the control unstimulated PMN (p < 0.01). The levels of IL-1 beta, TNF-alpha and IL-8 released from cells stimulated with P. gingivalis or C. ochracea LPS were significantly lower than those of cells stimulated with A. actinomycetemcomitans or E. coli LPS (p < 0.05). On the other hand, substantially greater amounts of IL-1ra were released from PMN stimulated with each LPS and from control unstimulated PMN during the first 6 h, and then significantly greater amounts of IL-1ra were secreted by PMN stimulated with A. actinomycetemcomitans and E.coli LPS during the following 12 h (p < 0.01). The inhibitory effects of IL-1ra on the biological activity of IL-1 in the supernatants of PMN were examined by the thymocyte comitogen proliferation assay. The supernatants of PMN stimulated with each LPS showed less biological IL-1 activity as compared with the same doses of recombinant human IL-1 beta detected by enzyme-linked immunosorbent assay. Furthermore, no activity was detected in the supernatants of PMN stimulated with P. gingivalis or C. ochracea LPS. These findings demonstrated that LPS from periodontopathic bacteria were capable of stimulating PMN to release not only pro-inflammatory cytokines but also their inhibitors such as IL-1ra. Different secretion levels of these cytokines and their biological activities induced by the various LPS might be important in the onset and progression of periodontal diseases.

Adult↗
PubMed1997

[Prophylactic effect of black tea extract as gargle against influenza].

We examined whether gargling with black tea prevents influenza infection. Tests were carried out during a five month period (October 1992 to March 1993). The control group that followed their normal daily routine, whereas the test group that gargled with 0.5 w/v% black tea extract twice daily (at 8 a.m. and 5 p.m.). Influenza viruses were isolated from influenza patients and an antigen analysis was carried out. As a result, two strains of influenza A viruses (H3N2) and ten strains of B virus were detected. An HI test was done using paired sera of the control group and the test group. The HI titers raised a four fold or greater in 48.8% (61/125) in the control group and 35.1% (35/134) in the test group. There was a significant difference (p < 0.05) between the control and test groups. These results indicate that black tea extract is effective as a prophylactic agent against influenza infection.

Humans↗
PubMed1997

Insulin resistance as an independent risk factor for carotid artery wall intima media thickening in vasospastic angina.

Studies have shown the presence of insulin resistance together with compensatory hyperinsulinemia in vasospastic angina as well as obstructive coronary artery disease. There is growing evidence that the development of coronary atherosclerosis may be closely related to systemic atherosclerosis as well as coronary spasm. However, no information is available about the possible relationship between insulin resistance and the existence of carotid atherosclerosis in vasospastic angina without segmental stenosis or luminal irregularities in coronary angiograms. To evaluate the independent effect of insulin resistance on carotid intima media thickening, we performed insulin sensitivity tests (steady-state plasma glucose method) on 40 patients with vasospastic angina and 24 control subjects with angiographically intact coronary arteries. Both oral glucose tolerance tests and lipid analyses were performed. Using B-mode ultrasonography, we assessed intima media thickness and plaque formation of common carotid arteries in these subjects. The steady-state plasma glucose level in the vasospastic angina group was about twofold higher than that of the control group, confirming the presence of insulin resistance in patients with vasospastic angina. The patients with vasospastic angina showed a significant increase in the average intima media thickness of the carotid wall and frequency of plaque formation, although they were comparable to the control subjects in risk factors other than insulin resistance. The intima media thickness was correlated with age (r = .62, P < .001), 2-hour insulin area (r = .45, P < .01), and steady-state plasma glucose level (r = .68, P < .0001) in patients with vasospastic angina. Similar correlations were observed in the control subjects. Multiple regression analyses of data indicated that 67% of the variation in the intima media thickness could be accounted for by age, steady-state plasma glucose level, and cigarette-years in vasospastic angina. In addition, differences in IMT were independently related to vasospastic angina. These results suggest that insulin resistance in association with compensatory hyperinsulinemia may be an important pathogenic factor for the development of coronary artery spasms and systemic early atherosclerosis.

Adult↗
PubMed1997

Left ventricular hypertrophy precedes other target-organ damage in primary aldosteronism.

To elucidate whether there is a difference in the progression of target-organ damage between primary aldosteronism and essential hypertension, we compared left ventricular hypertrophy and extracardiac target-organ damage in 23 patients with primary aldosteronism and 116 patients with essential hypertension. The severity of hypertensive retinopathy and the renal involvement in primary aldosteronism were subclinical and similar to those in essential hypertension without left ventricular hypertrophy but significantly milder than those in essential hypertension with left ventricular hypertrophy. There was a strongly significant correlation between the degree of left ventricular mass index and the severity of hypertensive retinopathy and renal involvement independent of office blood pressure in essential hypertension. In contrast, left ventricular hypertrophy markedly progressed despite the mild extracardiac target-organ damage in primary aldosteronism. Left ventricular end-diastolic dimension index in primary aldosteronism (3.16+/-0.50 cm/m2) was significantly larger than in essential hypertension without (2.87+/-0.23) and with (2.88+/-0.22) left ventricular hypertrophy. On the other hand, there was no difference in extracardiac target-organ damage between 13 primary aldosteronism patients with eccentric left ventricular hypertrophy and the 26 essential hypertensive patients with eccentric left ventricular hypertrophy. The results suggest that predominantly volume load, be it due to aldosteronism or other mechanisms, resulting in eccentric left ventricular hypertrophy is less likely to cause extracardiac target-organ damage than hemodynamic or nonhemodynamic mechanisms resulting in concentric left ventricular hypertrophy.

Adult↗
PubMed1997

A simple quantitative measurement of mRNA of human beta-actin by reverse transcription competitive PCR with a compact digital camera.

Reverse transcription (RT) competitive polymerase chain reaction (PCR) is a sensitive and useful technique for the absolute quantitation of mRNA level. We developed a competitive PCR method with a compact digital camera DC 40 (Eastman Kodak Company, NY, U.S.A.) for the measurement of human beta-actin cDNA (mRNA), a reference gene in an analysis for target gene expression. The devised method, compared with currently used methods, was easy, safe, sensitive, and highly reproducible to assay an infinitesimal level of cDNA (mRNA).

Actins↗
PubMed1997

Affinity for [3H]iloprost binding sites and cAMP synthesis activity of a 3-oxa-methano prostaglandin I1 analog, SM-10906, in human platelets and endothelial cells.

SM-10902 ((+)-methyl [2-[(2R,3aS,4R,5R,6aS)-octahydro-5-hydroxy-4-[(E)-(3S,5S)-3- hydroxy-5-methyl-1-nonenyl]-2-pentalenyl]ethoxy]acetate) and its free acid, SM-10906 are new stable 3-oxa-methano prostaglandin (PG) I1 analogs. Their affinities for [3H]iloprost and [3H]PGE2 binding sites in human platelets and human umbilical vascular endothelial cells were compared with those of the PGI2 analog iloprost, PGE1 and PGE2 by the radioligand binding assay method. The cyclic AMP (cAMP) synthesis activity of these drugs were also determined in human umbilical vascular endothelial cells. We found that SM-10906 apparently displaced [3H]iloprost binding to the membrane fractions in those cells since the pKi values were 6.30 in platelets, 7.52 in vein endothelial cells and 6.31 in the arterial endothelial cells. The pKi values of SM-10906 for [3H]PGE2 binding sites were significantly lower than those obtained for [3H]iloprost binding. SM-10902, which is a prodrug of SM-10906, showed low affinity for [3H]iloprost binding sites in those cells. SM-10906 also dose-dependently enhanced the cAMP level in the vascular endothelial cells. Thus, these findings indicate that SM-10906 binds to [3H]iloprost binding sites and exhibits pharmacological functions such as an anti-platelet action and a cytoprotective action in endothelial cells through the elevation of intracellular cAMP contents.

Adult↗
PubMed1997

Inhibition of collagenases from mouse lung carcinoma cells by green tea catechins and black tea theaflavins.

Theaflavin and theaflavin digallate, which are components of black tea were examined by in vitro invasion assay with mouse Lewis lung carcinoma LL2-Lu3 cells, which are highly metastatic. The compounds inhibited invasion by the tumor cells. Gelatin zymography showed that the cells secreted matrix metalloproteinases (MMPs), probably including MMP-2 and MMP-9, which may be involved in tumor cell invasion and metastasis. Theaflavin and theaflavin digallate also inhibited MMPs from the culture medium of these tumor cells, as did (-)-epigallocatechin gallate. These results suggest that theaflavin, theaflavin digallate, and (-)-epigallocatechin gallate inhibit tumor cell invasion by inhibiting type IV collagenases of the LL2-Lu3 cells.

Animals↗
PubMed1997

Effects of central nervous stimulants on spino-bulbo-spinal reflex potentials in cats.

Effects of central nervous stimulants on the spino-bulbo-spinal reflex potential were evaluated in anesthetized intact cats, and compared with those on segmental spinal reflex potentials in anesthetized spinal cats. In spinal cats, strychnine augmented polysynaptic reflex potential, picrotoxin inhibited dorsal root reflex potential, aminopyrine potentiated mono- and poly-synaptic reflex potentials but inhibited dorsal root reflex potential, and 4-aminopyridine potentiated all the three types of segmental reflex potentials. A combination of fenbufen, a non-steroidal antiinflammatory agent, and enoxacin, a new quinolone antimicrobial, inhibited all the three types of segmental reflex potentials. In contrast, all these drugs consistently produced an augmentation of the spino-bulbo-spinal reflex potential in anesthetized intact cats. From these findings, we suggest that the spino-bulbo-spinal reflex potential may be used as an electrophysiological parameter for the evaluation of central nervous stimulants.

Action Potentials↗