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Biomedical subjects

S Yamada

Publications and source records attributed to S Yamada.

At least 595 records · Page 33Linked to original sources
PubMed1997

Osteoclastic resorption of calcium phosphate ceramics with different hydroxyapatite/beta-tricalcium phosphate ratios.

To study the influence of calcium phosphate ceramic solubility on osteoclastic resorption, neonatal rabbit bone cells were cultured for 2 days on hydroxyapatite (HA), beta-tricalcium phosphate (beta-TCP) and two types of biphasic calcium phosphate (BCP) with HA/beta-TCP ratios of 25/75 and 75/25. Solubility was regulated by varying the ratio of less-soluble HA and more-soluble beta-TCP. After removal of stromal cells by pronase E treatment, ceramic surfaces were observed by scanning electron microscopy. Osteoclasts resorbed BCP most extensively, with an HA/beta-TCP ratio of 25/75, producing typical lobulated, zig-zag track-like resorption lacunae. On pure beta-TCP, which had the highest solubility in acid, osteoclasts formed smaller discontinuous island-like lacunae. The resorption pattern may have been modified by the large number of calcium ions released into the acidic microenvironment at the osteoclast-ceramic interface. No resorption lacunae were found on the other specimens. The extent of osteoclastic resorption of calcium phosphate ceramics might, to a certain degree, be proportional to solubility, although this was not the case when solubility was very high. It would appear that ceramic solubility influences osteoclast resorption activity.

Animals↗
PubMed1997

Optical recording of neural signals evoked by greater superficial petrosal nerve stimulation in rat.

Electrical responses to greater superficial petrosal (GSP) nerve stimulation in a rat geniculate ganglion (GG) preparation were assessed by simultaneous multi-site-optical recording. The GG/GSP nerve preparations were dissected out and were stained with a voltage-sensitive dye (RH155). Application of depolarizing square pulses to the GSP nerve fibers using a suction electrode evoked optical (absorbance) signals that were recorded simultaneously from many contiguous regions using a 24 x 24 photodiode matrix array with 448 active elements. Those optical signals were observed along the left half area of the GSP nerve. As the distance from the site of stimulation increased, the optical signals appeared to conduct with increasing time-delay. From the relationship between the peak latency and distance, the conduction velocity was estimated to be about 0.4 m/s. Tetraethylammonium affected the duration of the optical signals, and the signals disappeared in solutions containing tetrodotoxin (TTX) or in Na(+)-deficient solutions. The optical signals evoked by the GSP nerve stimulation are considered to be due to the action potentials propagating along the GSP of unmyelinated axons.

Afferent Pathways↗
PubMed1997

Measles virus-specific immunoglobulin G subclass response in serum and cerebrospinal fluid.

BACKGROUND: While many previous studies have focused on the impairment in the cellular immunity during measles virus infection, to date, a limited amount of data is available concerning the virus-specific IgG subclass response during measles virus infection. OBJECTIVE: The purpose of this study is to analyze the measles virus infection on the basis of virus-specific IgG subclass (G 1 and G 3). STUDY DESIGN: Frozen-stored, serum and/or cerebospinal fluid samples from three groups of patients were tested retrospectively; Group 1 comprised 14 patients with measles primary infection, group 2, ten patients with reinfection/vaccine failure, and group 3, seven patients with subacute sclerosing panencephalitis. The method used was a modified ELISA method utilizing the Enzygnost IgG detection kit with mouse-monoclonal antibodies (clone HP6091 for IgG 1 and clone HP6050 for IgG 3). Avidity testing for each subclass IgG was also performed for selected samples by means of an 8 M urea-denaturation method. RESULTS: In group 1, the IgG 3 could be detected in serum within 7 days from the onset of rash more frequently than IgG 1. In the cases of group 2, both subclasses were detected in very acute phase serum samples. In these cases, the IgG 1-specific avidity was always higher than that of IgG 3. In group 3, the subclass IgGs detected in the cerebrospinal fluid had a lower avidity than those in the serum. CONCLUSIONS: Our results suggested that in measles virus infection, like other viral infections, the IgG 3 response normally occurs before the IgG 1 response, and plays a major role in the acute phase immunity during the primary infection, while the IgG 1 plays a major role in the maintenance of immunity. Continuously produced IgG 1 and IgG 3 in the central nervous system in cases of subacute sclerosing panencephalitis may be derived from cell populations different from those in the blood.

Adolescent↗
PubMed1997

Incidence and clinical symptoms of Aeromonas-associated travellers' diarrhoea in Tokyo.

In a survey examining the causes of travellers' diarrhoea treated in Tokyo between July 1986 and December 1995, Aeromonas species were isolated from 1265 (5.5%) of 23,215 travellers returning from developing countries. Aeromonas species were the fourth most frequent enteropathogen isolated, following enterotoxigenic E. coli (8.5%), Salmonella spp. (7.6%) and Plesiomonas shigelloides (5.6%). Aeromonas species were found in 1191 (5.6%) of 21,257 patients with diarrhoea and in 74 (3.8%) of 1958 healthy individuals without diarrhoea. Mixed infection was observed in 512 (40.5%) cases. No significant difference in the prevalence of Aeromonas by year, season, age distributions, or sex was observed, but a slight difference was noted depending on the country where the travellers visited. Of the 1265 Aeromonas isolates, 893 strains (70.6%) were A. veronii biovar sobria, 330 (26.1%) were A. hydrophila, and 42 (3.3%) were A. caviae. The clinical symptoms of patients from whom Aeromonas species was isolated as the only potential enteric pathogen were almost similar, which were watery diarrhoea (about 60%), abdominal cramps (43%), fever (around 15%), and nausea or vomiting (13%). Although the severity of illness was milder than that of enterotoxigenic E. coli alone, these data suggest that Aeromonas species are important enteric pathogens in travellers' diarrhoea.

Aeromonas↗
PubMed1997

Enhanced expression of cytokine-induced neutrophil chemoattractant (CINC) by bronchoalveolar macrophages in cerulein-induced pancreatitis rats.

The role of bronchoalveolar macrophages (BAMs) in the aggravation of cerulein-induced pancreatitis was studied by measuring expression of cytokine-induced neutrophil chemoattractant (CINC) in vitro. Pancreatitis was induced by four intramuscular injections of cerulein (50 microg/kg at 1-hr intervals). Pancreatitis rats were injected intraperitoneally with 30 mg/kg lipopolysaccharide (LPS) 6 hr following the first cerulein injection as a septic challenge. Rats were divided into four groups: group I, nonpancreatitis without LPS; group II, pancreatitis without LPS; group III, nonpancreatitis with LPS; and group IV, pancreatitis with LPS. Hyperactivity of BAMs in response to LPS was assessed as a function of in vitro CINC production. CINC concentrations of the serum and bronchoalveolar lavage fluid in group IV were significantly higher than those in groups I, II, and III. BAMs in group II harvested 6 hr following the first cerulein injection had significantly greater CINC production than those in group I. Northern blot analysis revealed abundant CINC mRNA transcripts in BAMs from groups III and IV. Additionally, myeloperoxidase activity in the lung of group IV rats 8 and 12 hr following the first cerulein injection was significantly higher than that in group I, II, and III rats. Significant differences in static lung compliance in group IV were found compared with groups I, II, and III. These results indicate that BAMs from rats with cerulein-induced pancreatitis were primed and had enhanced release of CINC following LPS exposure. Enhanced expression of CINC may modulate the pathogenesis of pancreatitis-associated lung injury complicated with sepsis.

Acute Disease↗
PubMed1997

Recombinant human hepatocyte growth factor facilitates biliary transport after hepatocyte transplantation in Eisai hyperbilirubinemic rats.

Hepatocyte transplantation may offer an attractive treatment for inborn errors of liver metabolism. However, factor(s) are required as stimuli to induce proliferation of the limited number of hepatocytes transplanted. The Eisai hyperbilirubinemic rat (EHBR) is a Sprague-Dawley (SD) mutant rat with conjugated hyperbilirubinemia. EHBRs have impaired canalicular excretory transport of organic anions, bile acid glucuronide, and sulfate. Recombinant human hepatocyte growth factor (rhHGF) (100 microg/kg) was injected intravenously at 2-hr intervals for 10 hr, immediately and 35 days following the intraportal injection of 1 x 10(7) wild-type SD rat hepatocytes. Serum bilirubin concentrations decreased significantly within 35 days and were maintained at significantly reduced levels for 120 days following transplantation. Biliary excretion was demonstrated by the biliary transport of indocyanine green and sulfobromophthalein sodium into the bile. These results indicate that hepatic transport of bile acid conjugates in EHBRs can be restored by hepatocyte transplantation combined with repeated administration of exogenous rhHGF, in conjunction with functioning of the recipient's excretory biliary system.

Animals↗
PubMed1997

The application of three-dimensional quantitative computed tomography to the maxillofacial skeleton.

OBJECTIVES: To develop a method for three-dimensional quantitative computed tomography (QCT) of the maxillofacial skeleton. METHODS: The linearity of reference phantom consisting of five hydroxyapatite (HA) rods was tested under various conditions, including the size of field of view, the position of object, and reconstruction algorithm, on three different scanners. The calibrated HA concentration value and the absolute Ca content of the mandible removed from fresh cadaver was compared in order to evaluate the calibration error. RESULTS: There was a high correlation between average CT number and HA concentration in the phantom rods. There was a 4-5% difference in results from the three scanners. High density areas, corresponding to more than 75% HA, were extracted from the original image. Data were reconstructed three-dimensionally and combined using a 32-bit computer system. A three-dimensional distribution of bone density superimposed on the maxillofacial skeleton was produced. CONCLUSION: Three-dimensional QCT of the maxillofacial skeleton has potential as a means of analysing bone density. Difference in performance of different CT scanners should be considered when comparing results.

Adolescent↗
PubMed1997

Neutrophil elastase inhibitor reduces neutrophil chemoattractant production after ischemia-reperfusion in rat liver.

BACKGROUND & AIMS: Neutrophils are important in the development of tissue injury induced by ischemia-reperfusion. The ability of an inhibitor of neutrophil elastase (ONO-5046) to protect against ischemia-reperfusion injury in rat liver was investigated by measuring serum concentrations of cytokine-induced neutrophil chemoattractant. METHODS: Liver ischemia was induced in rats by occluding the portal vein for 30 minutes, and ONO-5046 or anticoagulants were injected intravenously 5 minutes before vascular clamping. RESULTS: Serum concentration of cytokine-induced neutrophil chemoattractant increased after reperfusion, reached a maximum at 6 hours, and then gradually decreased. However, pretreatment of animals with heparin (50 U/kg), antithrombin III (250 U/kg), or ONO-5046 (10 mg/kg) resulted in significantly smaller increases in the serum concentration of cytokine-induced neutrophil chemoattractant after reperfusion. Pretreatment with both ONO-5046 and heparin, or both ONO-5046 and antithrombin III, produced additive effects. Pretreatment of rats with both ONO-5046 and heparin or both ONO-5046 and antithrombin III also inhibited the increase in cytokine-induced neutrophil chemoattractant mRNA in liver. These combined treatments significantly reduced the increases in both the number of neutrophils accumulated in the liver and the hepatic activity of myeloperoxidase. CONCLUSIONS: Cytokine-induced neutrophil chemoattractant production after ischemia-reperfusion in the liver is mediated by neutrophil elastase and activation of coagulation within the hepatic microcirculation.

Animals↗
PubMed1997

Enhanced expression of cytokine-induced neutrophil chemoattractant in rat hepatic allografts during acute rejection.

The kinetics of messenger RNA (mRNA) and protein levels of cytokine-induced neutrophil chemoattractant (CINC) in rat hepatic allografts during acute rejection were investigated. Infiltrating cells were identified by double immunostaining with anti-CINC and anti-macrophage monoclonal antibodies, ED1 and ED2. The serum CINC concentration in untreated hepatic allograft recipients increased significantly at a constant rate over time after transplantation. No significant increases in serum CINC concentrations were observed in hepatic isografts or allografts treated with the immunosuppressant FK506. The number of neutrophils in untreated hepatic allografts increased significantly at a constant rate. Conversely, neutrophil accumulation in isografts or allografts treated with FK506 was much less than in untreated hepaticallografts. Immunostaining revealed that in the portal areas, mononuclear cells infiltrating untreated allograft liver were mainly positive for CINC and that CINC+ cells represented a subpopulation (approximately 25%) of the ED1+ cells. On the other hand, in the sinusoidal areas CINC+ cells were scattered and mainly positive for ED2. Levels of CINC mRNA in liver tissues taken from untreated hepatic allografts increased after transplantation, peaked on day 5, and decreased thereafter. Hepatic allografts treated with FK506 or isografts showed much lower levels of CINC mRNA than untreated allografts. Allogeneic mixed lymphocyte reactions induced CINC production. The cellular source of CINC was mononuclear cells. CINC production in mixed lymphocyte reactions was inhibited in the presence of anti-tumor necrosis factor alpha (TNF-alpha) antibody. These results suggest that enhanced expression of CINC mRNA and prominent accumulation of neutrophils in the liver grafts are characteristic features of the immune response during acute rejection.

Animals↗
PubMed1997

Effect of VA-045, a novel apovincaminic acid derivative, on closed head injury-induced neurological dysfunction in aged rats.

Effects of VA-045, a novel apovincaminic acid derivative, on behavioral outcome following closed head injury (CHI) were examined in aged (21-28 months) rats. CHI was induced by dropping a 400 g weight through a tube from 150 cm above a steel helmet placed on the vertex. Beam balancing latency, neurological deficits and body weight were recorded before CHI and for up to 14 days after CHI. When compared with the sham group, all measurements of parameters of behavioral outcome in the CHI group were significantly worsened after CHI. Intraperitoneal administration of VA-045 (1 and 3 mg kg-1) or thyrotropin-releasing hormone (TRH, 10 mg kg-1) and vehicle was started 24 h after CHI, and continued once daily for 13 days. VA-045 but not TRH significantly overcame the CHI-induced neurological deficits, shortened the latency of beam balancing and decreased body weight loss. VA-045 may prove useful for treating aged patients with disturbances of consciousness or motor deficits after CHI.

Age Factors↗
PubMed1997

Supratentorial primary intra-axial tumors in children. MR and CT evaluation.

PURPOSE: To evaluate the MR and CT features of pediatric supratentorial intra-axial tumors with respect to differential diagnosis and the role of each investigation modality. MATERIAL AND METHODS: MR and CT findings in 40 children with 12 types of pathologically proven histological tumors were reviewed. RESULTS: The location of tumors might be one clue to differential diagnosis. In our material, cysts (60%), calcifications (45%), and intratumoral hemorrhages (27%) were found in the tumors. Characteristic features noted in some lesions included: peritumoral hemosiderin deposition in cavernous angiomas; intratumoral flow void in a choroid plexus carcinoma and in glioblastomas; and hemicerebral atrophy in germinomas. A comparison between malignant and benign tumors showed perifocal edema and a mass effect to be significantly more common in malignant lesions. Homogeneous enhancement suggested a benign tumor and an inhomogeneous pattern represented malignancy, while the lack of obvious enhancement did not always suggest benignity. Intratumoral calcium deposition was a not uncommon finding in malignant tumors. CONCLUSION: In most cases, the exact diagnosis should be made by histological examination but it is important for treatment planning that the appropriate depiction of tumor extension and tissue characterization be made by MR and CT.

Adolescent↗
PubMed1997

A wide spectrum of collagen vascular and autoimmune diseases in transgenic rats carrying the env-pX gene of human T lymphocyte virus type I.

To investigate the pathogenesis of human T lymphocyte virus type I (HTLV-I)- related diseases, the env-pX gene of HTLV-I was introduced into the germline of inbred Wistar-King-Aptekman-Hokudai rats. A wide spectrum of collagen vascular diseases was evident in the transgenic rats, including chronic destructive arthritis similar to rheumatoid arthritis, necrotizing arteritis mimicking polyarteritis nodosa, polymyositis, myocarditis, dermatitis, and chronic sialoadenitis and dacryoadenitis resembling Sjögren's syndrome in humans. Thymic atrophy with the depletion of CD4 and CD8 double-positive thymocytes was also observed. In these animals, a number of autoantibodies, including high titers of rheumatoid factor, were present in the serum. We propose that the HTLV-I env-pX gene region may play a pathogenetic role in the development of collagen vascular and autoimmune diseases associated with autoimmune phenomenon.

Animals↗
PubMed1997

Integrin alpha5 is expressed on human luteinizing granulosa cells during corpus luteum formation, and its expression is enhanced by human chorionic gonadotrophin in vitro.

We previously reported that human granulosa cells (GC) express integrin alpha6beta1, in large follicles and early corpus luteum (CL). In this study, we examined the expression of integrin alpha5 and fibronectin (FN) by immunohistochemistry. Integrin alpha5 was undetectable on human GC in preovulatory follicles, but it was intensely expressed on luteinizing GC of CL in the early luteal phase, and it was weakly expressed on large luteal cells (LL) in the midluteal phase. FN was similarly expressed between GC/LL. Thus, integrin alpha5 and FN were stage-specifically expressed on/between luteinizing GC in the early luteal phase. Next we examined the effect of human chorionic gonadotrophin (HCG) on expression of integrin alpha5 on luteinizing GC in vitro. GC obtained from preovulatory follicles were cultured for 3 days without (control) or with HCG (1 IU/ml), and expression of integrin alpha5 was examined by flow cytometry. Although the positivity rate did not differ, the mean relative fluorescence intensity was 3.4-fold higher in the HCG-treated group (n = 8, P < 0.01). These findings indicate that integrin alpha5 is rapidly expressed on GC during luteinization, probably under LH stimulation, and suggest that integrin alpha5 is involved in CL formation via interaction with its ligand FN.

Antigens, CD↗
PubMed1997

Immunohistochemical localization of the LH/HCG receptor in human ovary: HCG enhances cell surface expression of LH/HCG receptor on luteinizing granulosa cells in vitro.

We examined the immunohistochemical localization of luteinizing hormone (LH)/human chorionic gonadotrophin (HCG) receptor (LH-R) in the human ovary using the anti-human LH-R monoclonal antibody, 3B5. In the antral follicles, LH-R was detected on theca interna cells. In pre-ovulatory follicles, granulosa cells also expressed LH-R. During corpus luteum formation, granulosa cells seemed to increase the expression of LH-R, and in corpus luteum of mid-luteal phase, large luteal cells expressed LH-R more intensely than small luteal cells. In the regressing corpus luteum, LH-R was almost undetectable on both luteal cells, whereas in the corpus luteum of early pregnancy, LH-R continued to be expressed on large luteal cells. The granulosa cells obtained from the patients undergoing in-vitro fertilization therapy were cultured for 3 days in serum-free medium, without or with HCG (10 IU/ml) and tumour necrosis factor (TNF)alpha (10 ng/ml). Flow cytometry showed that the expression of LH-R on the cell surface of luteinizing granulosa cells was enhanced by HCG, but was unaffected by TNFalpha. These results suggest that the main target cells for LH/HCG change from theca interna cells/small luteal cells to granulosa cells/large luteal cells during ovulation, corpus luteum formation, and differentiation into the corpus luteum of pregnancy, probably under the influence of LH/HCG.

Adolescent↗
PubMed1997

Expression of plasma membrane water channel genes under water stress in Nicotiana excelsior.

Deduced amino acid sequences encoded by the cDNAs related to the MIP gene family from Nicotiana excelsior were characterized. Phylogenetic characterization of the products of corresponding genes named NeMip1, NeMip2, and NeMip3 strongly suggested that they are water channel proteins localized in the plasma membrane. Organ specificity of the gene expression was examined in leaves, roots, and reproductive organs. NeMip1 was expressed in roots and reproductive organs; however, it was hardly detectable in leaves. Two other genes, NeMip2 and NeMip3, were expressed in all of organs examined. mRNA accumulation from the genes was investigated in leaves under salt- and drought-stresses. The results demonstrated that mRNA accumulation from all three genes increased under salt- and drought-stresses within one day. However, they showed different accumulation patterns. In addition to their up-regulation under salt- and drought-stresses, daily changes in NeMip2 and NeMip3 mRNA accumulation was observed under unstressed conditions in leaves.

Amino Acid Sequence↗
PubMed1997

The expression of an aquaporin promoter from Mesembryanthemum crystallinum in tobacco.

The promoter region of the MipB gene encoding an aquaporin from Mesembryanthemum crystallinum was isolated and used in a transcriptional fusion to control uidA expression in tobacco. The sequence of the promoter was determined for 2 kb upstream of the translation initiation site. Three start sites were utilized with approximately equal frequency, located 176, 170, and 161 bases, respectively, upstream of the translation initiation site. As judged by analysis of GUS expression, promoter MipB retains its specificity in transgenic tobacco. In germinating seedlings, all cells showed GUS expression of different intensities with the strongest signals in root meristems. In older seedlings, GUS staining was observed in rapidly expanding cells--root and apical meristem, and lateral root primordia. In mature plants, strong GUS activity was located to glandular trichomes, subepidermal cells of the stem and petioles, to cells surrounding vascular tissues as well as in xylem parenchyma cells. In immature floral organs, GUS expression was strong in sepals, petals, stamen, and pistil. The intensity declined as they matured. In general, this promoter was active in rapidly expanding cells and cells with high water flux capacity, especially in the xylem parenchyma.

Aquaporins↗
PubMed1997

Does plasma free-3-methoxy-4-hydroxyphenyl(ethylene)glycol increase in the delirious state? A comparison of the effects of mianserin and haloperidol on delirium.

Sixty-six patients (47 men, 19 women, mean age 65 years) with delirium were treated with mianserin (10-60 mg/day) or haloperidol (2-6 mg/day) at Kurume University Hospital. The clinical effects of these drugs were compared before and after treatment using the Delirium Rating Scale. At the same time, blood was sampled to analyse plasma mianserin, free-3-methoxy-4-hydroxyphenyl(ethylene)glycol (MHPG) and homovanillic acid concentrations. Marked improvement after 1 week was observed in 69.4% of patients undergoing mianserin treatment, and in 70.6% of those receiving haloperidol. A statistically significant difference in the clinical effects of these drugs was not observed. Although improvement in the delirious state and a decrease in the plasma free-MHPG concentration were observed after drug administration, the plasma free-homovanillic acid concentration showed no significant change. The higher plasma free-MHPG concentration in the delirious state suggests the existence of a preparatory state whereby noradrenaline metabolism is involved in the appearance of the abnormal behaviour associated with delirium. These data suggest that free-MHPG concentrations could potentially be used as a predictor of delirium.

Aged↗