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Biomedical subjects

Y Koyama

Publications and source records attributed to Y Koyama.

At least 127 records · Page 7Linked to original sources
PubMed1999

Efficacy of transradial primary stenting in patients with acute myocardial infarction.

We conducted a prospective observational study to assess the effectiveness of "transradial primary stenting" in 33 patients with acute myocardial infarction, along with acute risk stratification and accelerated patient care. With use of adequate inclusion and exclusion criteria, the radial artery can be used as an access site for catheterization, and transradial primary stenting can be performed rapidly and successfully by trained coronary interventionalists.

Aged↗
PubMed1999

Poly(ADP-ribose) polymerase interacts with novel Drosophila ribosomal proteins, L22 and l23a, with unique histone-like amino-terminal extensions.

Poly(ADP-ribose) polymerase (PARP) is a nuclear enzyme that recognizes and binds to the nicks and ends of DNA, and catalyses successive ADP-ribosylation reactions. To clarify the function of PARP at the molecular level, we searched proteins which interact with PARP. In the auto-modification domain of PARP in Drosophila, there is a putative leucine-zipper motif which can interact with other protein molecules. To find interacting proteins we examined the auto-modification domain of Drosophila PARP, using the Far-Western screening method. From six independent cDNA clones isolated, we characterized two clones, PBP-3 and PBP-12. The predicted amino acid sequences from 109 to 269 of PBP-3 and from 184 to 312 of PBP-12 had more than 62% identities to mammalian L23a (rpl23a) and L22 (rpl22), the ribosomal proteins of the large subunit. This indicated that PBP-3 and PBP-12 are Drosophila homologues of L23a and L22, respectively. These Drosophila ribosomal protein L22 and L23a have additional Ala-, Lys- and Pro-rich sequences at the amino terminus, which have a resemblance to the carboxy-terminal portion of histone H1. Thus, Drosophila L22 and L23a might have two functions, namely the role of DNA-binding similar to histone H1 and the role of organizing the ribosome.

Amino Acid Sequence↗
PubMed1999

Cell culture test of TCP/CPLA composite.

Thermoplastic polymers filled with a ceramic powder (here described as a "composite") of beta-tricalcium phosphate (TCP) and copoly-L-lactide (CPLA) was prepared by a heat-kneading method. The TCP/CPLA composite obtained had a three-point bending strength of 51.26 +/- 634 MPa, a Young's modulus of 5.18 +/- 1.11 GPa, and a fracture strength of 52.64 +/- 2.975 MPa, which is sufficient for usage as an artificial bone implant material. According to cell culture tests using MC3T3-E1 cells, the TCP/CPLA composite showed no cytotoxicity and the cells were in close contact with the surfaces of the composite without any observable morphological change. These results suggest that a composite consisting of osteoconductive TCP and biodegradable CPLA is suitable as a bioactive artificial bone material.

Absorbable Implants↗
PubMed1999

BQ788, an endothelin ET(B) receptor antagonist, attenuates stab wound injury-induced reactive astrocytes in rat brain.

Endothelins (ETs) are suggested to be involved in pathological or pathophysiological responses on brain injuries. In the present study, an involvement of ETs on activation of astrocytes in vivo was examined by using selective endothelin receptor antagonists. A stab wound injury on rat cerebral cortex increased immunoreactive ET-1 at the injured site. GFAP-positive [GFAP(+)] and vimentin-positive [Vim(+)] cells appeared at the injured site in 1 day to 2 weeks after the injury. A continuous infusion of BQ788, a selective ETB receptor antagonist, into cerebral ventricle (23 nmole/day) attenuated increase in the numbers of GFAP(+) and Vim(+) cells after the injury. FR139317, a selective ETA antagonist (23 nmole/day), slightly decreased the number of Vim(+) cells but not that of GFAP(+) cells. Increase in the number of microglia/macrophages by a stab wound injury, which was determined by Griffonia simplicifolia isolectin B4 staining, was not affected by BQ788 and FR139317. These results suggest that activation of glial ETB receptors is one of the signal cascades leading to reactive astrocytes on brain injuries.

Animals↗
PubMed1999

The structure of an aggregate form of bacteriochlorophyll c showing the Qy absorption at 705 nm as determined by the ring-current effects on 1H and 13C nuclei and by 1H-1H intermolecular NOE correlations.

13C-enriched bacteriochlorophyll c (R[E, E] BChl cF) was suspended in chloroform to form an aggregate showing the Qy absorption at 705 nm. (1) The aggregate exhibited several largely split 13C-NMR signals suggesting the presence of non-equivalent BChl c molecules in the form of the piggyback dimer. (2) Changes in the 13C chemical shifts were traced when methanol was titrated to dissolve the aggregate, and the aggregation shifts (in reference to the monomeric state) were determined as a function of the amount of methanol titrated, and they were analyzed empirically. (3) The ring-current effects were calculated based on the loop-current approximation, and the results were compared with the observed aggregation shifts for 13C and 1H nuclei (the 1H aggregation shifts were determined by extrapolation of the data taken from Mizoguchi, T.; Limantara, L.; Matsuura, K.; Shimada, K.; Koyama, Y. J Mol Structure 1996, 379, 249-265). The results showed that the assembly of two straight columns consisting of the piggyback dimer stacked in the antiparallel orientation is the best choice as a model for the B705 aggregate. (4) Three-dimensional F1 13C-edited F3 13C-filtered heteronuclear single-quantum nuclear-Overhauser-effect spectroscopy was applied to the aggregate consisting of a 1:1 mixture of 13C-labeled and unlabeled BChl c in order to selectively detect the intermolecular 1H-1H NOE correlations. The NOE correlations were explained in terms of a straight column, supporting the above model.

Bacterial Proteins↗
PubMed1999

Functional CD40 ligand is expressed on epidermal Langerhans cells.

Epidermal Langerhans cells (LC) are bone-marrow-derived major histocompatibility complex (MHC) class II antigen-expressing antigen-presenting cells (APC) that comprise 1-3% of total epidermal cells (EC). LC express high levels of MHC class II antigen and augment costimulatory molecules such as B7-1, B7-2 during culture. In a previous report, using purified murine LC, we showed that freshly prepared LC (fLC) do not express CD40, whereas cLC express CD40. Tumor necrosis factor alpha (TNF-alpha) enhanced CD40 expression on LC during culture. We examined the expression of CD40L on LC and found that both fLC and cLC expressed mRNA for CD40L. FACS analysis revealed that cLC cultured for 36 h expressed CD40L but fLC did not. When we examined the cytoplasmic CD40L, however, both fLC and cLC expressed cytoplasmic CD40L. TNF-alpha, which up-regulated CD40 expression on LC during culture, did not modulate CD40L. Co-culture of purified LC ith anti-CD40L markedly inhibited the up-regulation of B7-1 expression on LC and caused partial inhibition of B7-2 expression during culture. These results indicate that CD40L is expressed on cLC, and that CD40L on LC modulates the expression of costimulatory molecules such as B7-1 and B7-2 on LC.

Animals↗
PubMed1999

Formation of GFAP cytoplasmic inclusions in astrocytes and their disaggregation by alphaB-crystallin.

In several neuropathological conditions, alphaB-crystallin and glial fibrillary acidic protein (GFAP) accumulate and form cytoplasmic inclusions in astrocytes. To explore the pathogenesis of the inclusions and the possible functions of the accumulated alphaB-crystallin, GFAP and alphaB-crystallin were overexpressed in cultured astrocytes by transient transfection. Human GFAP formed filamentous, cytoplasmic inclusions in mouse astrocytes, NIH3T3 cells, rat C6 glioma cells, and human U251 glioma cells. These human GFAP inclusions did not contain the endogenous vimentin or beta-tubulin, and the intermediate filament and microtubular networks of the transfected cells appeared normal. alphaB-crystallin and hsp25 were associated with the GFAP inclusions. Increasing intracellular alphaB-crystallin levels using recombinant adenoviruses, either before or after GFAP inclusions were formed, decreased the number of inclusion-bearing astrocytes and converted the human GFAP from an inclusion to a spread, filamentous form. These results suggest that alphaB-crystallin reorganizes abnormal intermediate filament aggregates into the normal filamentous network.

3T3 Cells↗
PubMed1999

Unassociated responses to two related task demands: a negative factor for improvement of unilateral spatial neglect.

Patients with relatively mild unilateral spatial neglect underwent the line bisection task with self-estimation, where they were asked two different questions about the relationship of their subjective midpoint to the line. For the first trial, all patients responded by "yes" when asked whether their subjective midpoint was placed at the center of the line, but by "left" or "right" when asked to indicate the longer segment of the bisected line. In the subsequent trials, they repeatedly reported that their subjective midpoints were placed at the true center, even after they had recognized their bisection errors when indicating the longer segment. Of the 32 patients, 28 kept on showing this pattern of responses in almost all the 30 trials. Moreover, the patients who could estimate the longer segment showed no improvement of line bisection throughout the trials. Their performances strongly depended upon the task demand regarding the subjective midpoint. These results demonstrate that the patients treated the two related tasks as independent. Accordingly, they could not improve their performances on one task with the feedback from their performances on the other. The lack of association between the responses to two related task demands may be one of the factors that prevent patients with unilateral spatial neglect from improving the deficit.

Aged↗
PubMed1999

Temporal changes in disaccharide composition of dermatan sulfate in the skin after epicutaneous application of hapten.

Glycosaminoglycans change their amount, structure and distribution with age, differentiation and pathologic conditions. In order to investigate temporal changes in dermatan sulfate in the skin during inflammation and subsequent healing, 2,4-dinitrofluorobenzene (DNFB) was applied once to the dorsal skin of female BALB/cA mice, and the disaccharide composition of dermatan sulfate was examined. Application of DNFB induced a transient increase in the thickness of the dermis, which reached a maximum on day 15 and decreased to the control level on day 35. The total amount of unsaturated disaccharides from dermatan sulfate per cm2 in the DNFB-treated skin showed a temporal pattern similar to that of the thickness of the dermis. Mol% of 4,5-unsaturated 2-sulfo-hexuronic acid-4-sulfated N-acetylgalactosamine (deltaDi-diSB), the second most abundant unsaturated disaccharide from dermatan sulfate, decreased rapidly on day 3 in the DNFB-treated skin, remained less than the control on days 7 and 15, and returned to the control level on day 35. These results suggest that a single application of DNFB induces temporal changes not only in the amount but also in the structure of dermatan sulfate.

Administration, Cutaneous↗
PubMed1999

Poorly differentiated sarcoma of the prostate causing obstructive acute renal failure: a case report.

A 12-year-old boy presented to the Naha Municipal Hospital complaining of back pain. After intravenous pyelography, computed tomography, magnetic resonance imaging, ultrasonography and biopsy, he was suspected to have sarcoma of the prostate and was referred to the University of the Ryukyus Hospital. Acute renal failure of the post renal type was evident, accompanied by minimal hydronephrosis. Emergency hemodialysis and right ureterostomy were performed, as was a transurethral prostate biopsy. The specimen showed a poorly differentiated sarcoma not otherwise classifiable. After recovery from surgery, chemotherapy was attempted over 2 months, but the patient died of tumor 250 days after admission.

Acute Kidney Injury↗
PubMed1999

Endothelins stimulate expression of cyclooxygenase 2 in rat cultured astrocytes.

Endothelin (ET) is one of the active endogenous substances regulating the functions of astrocytes. In the present study, we examined effects of ET on cyclooxygenase (COX) expression in cultured astrocytes. ET-3 (100 nM) caused transient increases in the expression of both COX2 mRNA and protein, but not those of COX1, in cultured astrocytes. ET-induced COX2 mRNA expression was suppressed by 5 microg/ml actinomycin D, 30 microM BAPTA/AM, inhibitors of protein kinase C (1-100 nM staurosporin and 100 microM H-7), 2 microM dexamethasone, and prolonged treatment with 100 nM phorbol 12-myristate 13-acetate. ET-3 stimulated production of prostaglandin (PG) E2 in cultured astrocytes. The effect of ET-3 on the PGE2 production was diminished by actinomycin D. Indomethacin and NS398, a selective COX2 inhibitor, comparably decreased both the basal and the ET-stimulated PGE2 production. Proliferation of cultured astrocytes was stimulated by 100 nM ET-3, and the increased proliferation was reduced by co-addition of 1 microM PGE2. Treatment with 1 microM PGE2 caused astrocytic morphological changes accompanied by disappearance of stress fibers, a prominent structure of organized cytoskeletal actin in cultured astrocytes. In the presence of 10 nM ET-3, PGE2 did not show an effect on astrocytic actin organization. The present study shows that ET is an inducer of astrocytic COX2 and suggests that ET-induced PGE2 production through COX2 may be involved in the regulation of astrocytic functions.

Animals↗
PubMed1999

Differential effects of cytokines and immunosuppressive drugs on CD40, B7-1, and B7-2 expression on purified epidermal Langerhans cells1.

Langerhans cells are MHC class II antigen-positive antigen-presenting cells in the epidermis. Recent studies have revealed that Langerhans cells express costimulatory molecules like B7-1 and B7-2 and the accessory molecule CD40. Although these molecules are important for the antigen-presenting function of Langerhans cells, little is known about the precise regulation of their expression on purified Langerhans cells. Using a panning technique, we purified epidermal Langerhans cells to around 95% purity. Freshly prepared Langerhans cells (fLC) expressed the mRNA for receptors for M-CSF (cfms), GM-CSF (GM-CSFR), and TNF-alpha (TNFRII). TNF-alpha markedly upregulated CD40 and B7-1 expression on Langerhans cells, but not B7-2 expression. GM-CSF moderately upregulated B7-1 and B7-2 expression, and slightly upregulated CD40 expression. M-CSF moderately upregulated B7-1 expression, but did not modulate CD40 or B7-2 expression. Dexamethasone (DEX) markedly inhibited CD40, B7-1, and B7-2 expression on Langerhans cells. Cyclosporin A (CsA) and FK506 slightly inhibited CD40 and B7-1 expression on Langerhans cells, but not B7-2. Furthermore, TNF-alpha restored the DEX-induced inhibition of CD40 expression on Langerhans cells, but not the inhibition of B7-1 or B7-2 expression. GM-CSF restored DEX-induced inhibition of CD40, B7-1, and B7-2 expression. M-CSF did not affect the DEX-induced inhibition of these molecule expressions. These data provide a better understanding of the role of selective cytokines and immunosupressive drugs in the modulation of the antigen-presenting capacity of Langerhans cells.

Animals↗
PubMed1999

Spatiotemporal changes of fibronectin, tenascin-C, fibulin-1, and fibulin-2 in the skin during the development of chronic contact dermatitis.

In order to elucidate how chronic inflammation affects the organization of the extracellular matrix in the skin, a prolonged allergic contact dermatitis was induced in a mouse by repeated application to the ear of 2,4-dinitrofluorobenzene every 3 d for 66 d. Subsequently, the spatiotemporal changes of fibronectin, tenascin-C, fibulin-1, and fibulin-2 in the skin were examined. In the acute phase of inflammation (day 3-day 12), the amount of fibronectin and tenascin-C increased markedly and were degraded, whereas the amount of fibulin-2 changed slightly. Abundant deposition of tenascin-C was observed in the connective tissue. Fibulin-1 and fibulin-2 distributed as fine fibrils. In contrast, the amounts of fibronectin and tenascin-C decreased and their degradation was suppressed in the chronic phase (day 15-day 66), but the amount of fibulin-2 increased. Tenascin-C was observed mainly at and underneath the epidermal basement membrane. In the subepidermal region, many fibulin-2-positive microfibrils were distributed. The amount and distribution of fibulin-1 did not change markedly in either phase. MMP-like enzymes of 62 kDa, probably activated MMP-2, were upregulated in the chronic phase, whereas components of 92, 85, or 67 kDa were highly induced in the acute phase. These results suggest that chronic inflammation in allergic contact dermatitis is associated with temporal changes in the expression, deposition, and degradation of inducible extracellular matrix components.

Animals↗
PubMed1999

Hepatocyte-specific distribution of catalase and its inhibitory effect on hepatic ischemia/reperfusion injury in mice.

To explore the possibility of using catalase for the treatment of reactive oxygen species (ROS)-mediated injuries, the pharmacokinetics of bovine liver catalase (CAT) labeled with 111In was investigated in mice. At a dose of 0.1 mg/kg, more than 70% of 111In-CAT was recovered in the liver within 10 min after intravenous injection. In addition, 111In-CAT was predominantly recovered from the parenchymal cells (PC) in the liver. Increasing the dose retarded the hepatic uptake of 111In-CAT, suggesting saturation of the uptake process. This cell-specific uptake could not be inhibited by coadministration of various compounds which are known to be taken up by liver PC, indicating that the uptake mechanism of CAT by PC is very specific to this compound. The preventive effect of CAT on a hepatic ischemia/reperfusion injury was examined in mice by measuring the GOT and GPT levels in plasma. A bolus injection of CAT at 5 min prior to the reperfusion attenuated the increase in the levels of these indicators in a dose-dependent manner. These results suggest that catalase can be used for various hepatic injuries caused by ROS.

Alanine Transaminase↗
PubMed1999

Risk factors for breast cancer in Japan, with special attention to anthropometric measurements and reproductive history.

BACKGROUND: Breast cancer incidence has increased rapidly in Japan recently, but there have been only a few studies on the risk factors for breast cancer in Japan. A case-control study was conducted to evaluate the roles of anthropometric and reproductive factors in the etiology of breast cancer in Osaka. METHODS: Based on information from a self-administered questionnaire at Osaka Medical Center for Cancer and Cardiovascular Diseases, body mass index, body weight and height were compared between 376 cases and 430 controls, together with other factors such as age at menarche, age at first delivery and family history of breast cancer by menopausal status. Logistic regression analysis was employed for adjusting confounding factors and estimating odds ratios with their 95% confidence interval for breast cancer. RESULTS: A body mass index of >25 was significantly associated with the risk among post-menopausal women (age-adjusted odds ratio: 1.90, 95% confidence interval: 1.10-3.24) as compared with the risk for a body mass index of < or = 20. A weight of > or =58 kg showed significantly increased risk compared with a weight of < or = 47 kg among post-menopausal women (1.83, 1.10-3.01), while height of > or = 159 cm showed a significantly elevated risk than height of < or = 149 cm among pre-menopausal women (2.51, 1.17-5.39). Age at menarche of < or = 13 years resulted in a higher risk of breast cancer among post-menopausal women, while age at first delivery of > or = 28 years was associated with the risk among pre-menopausal women. Family history of breast cancer was associated with the risk for breast cancer. CONCLUSIONS: These results were all very consistent with findings observed in western countries.

Adult↗
PubMed1999

Directed evolution of thermostable kanamycin-resistance gene: a convenient selection marker for Thermus thermophilus.

The whole-genome sequencing of an extreme thermophile, Thermus thermophilus, is now in progress. Like other genome projects, major concern is shifting from the sequence itself to post-sequencing research such as functional or structural genomics. Under such circumstances, the demand for convenient genetic-engineering tools is increasing. In this study we have increased the thermostability of a kanamycin-resistance gene product using strategies based on directed evolution in T. thermophilus to the upper limit of its growth temperature. The most thermostable mutant has 19 amino-acid substitutions, whereby the thermostability is increased by 20 degrees C, but the enzymatic activity is not significantly changed. Most of the mutated residues are located on the surface of the protein molecule, and, interestingly, five of the 19 substitutions are those to proline residues. The evolved kanamycin-resistance gene products could be used as selection markers at the optimum growth temperature of T. thermophilus. The development of such a convenient genetic-engineering tool would facilitate post-sequencing research on T. thermophilus.

Amino Acid Substitution↗
PubMed1999

Effects of posture on left ventricular diastolic filling during exercise.

BACKGROUND: Measuring the transmitral flow velocity with Doppler echocardiography is a useful method for evaluating left ventricular diastolic function. However, there are few data regarding the effect of posture during exercise on transmitral flow velocity. METHODS: The transmitral flow velocity with pulsed-wave Doppler echocardiography was measured during supine and upright bicycle ergometer exercise in 10 normal young men without cardiac disease (26.7 +/- 5.5 yr). RESULTS: The ratio of the early rapid filling wave to the atrial filling wave (E/A) was gradually decreased with increasing exercise intensity. At rest and during recovery, the E/A ratio was significantly higher (P < 0.01) in the supine position than in the upright position. This difference was caused mainly by the higher E wave in the supine position. However, E wave and E/A ratio did not differ between the upright and supine position during exercise. CONCLUSION: Although measurement of left ventricular filling is completely noninvasive and clinically useful for evaluating diastolic function, it was found that the E/A ratio was profoundly influenced by posture and exercise intensity. These results suggest that the potential influences of posture and exercise intensity on the filling velocities should be taken into account when interpreting diastolic function by Doppler echocardiography.

Adolescent↗