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Biomedical subjects

T Yamada

Publications and source records attributed to T Yamada.

At least 109 records · Page 6Linked to original sources
PubMed2002

Endocrine-disrupting effects of styrene oligomers that migrated from polystyrene containers into food.

The endocrine-disrupting effects of styrene dimers (SD: NSD-01, -08 and -09) and styrene trimers (ST: NST -01, -03 and -12), which migrated from polystyrene (PS) containers into instant food, were investigated together with styrene monomer (SM) using in vitro and in vivo assays. In the estrogen (ER) and androgen receptor (AR) binding assay, SM, SD and ST showed no binding activity at concentration of 10(-10)-10(-5) mol/l. In order to evaluate the estrogenic activity in vivo, the uterotrophic assay was conducted. When prepubertal and ovariectomized adult rats were dosed with SM, SD and ST for 3 days by subcutaneous injection, these compounds did not induce significant increase in uterine weight. Additionally, to evaluate anti-androgen activity in vivo, the Hershberger assay for anti-androgenic activity in the presence of testosterone treatment was conducted. When castrated, testosterone-treated immature male rats were dosed SM, SD and ST for 7 days by oral gavage, these compounds did not induce a decrease in the seminal vesicle, ventral prostate and levator ani plus bulbocavernosus muscle weights. To evaluate the effects on hormones other than sex hormones, the thyroid hormone receptor (TR) binding assay and rat serum prolactin (PRL) was conducted. In the TR binding assay, SM, SD and ST showed no binding activity at a concentration of 10(-5) mol/l. When ovariectomized rats were dosed with SM, SD and ST for 3 days by sc injection, the results showed there was no change in rat serum PRL. From the above these results, we concluded that SM, SD and ST exhibit no apparent estrogenic, androgenic, anti-androgenic and thyroid activity.

Animals↗
PubMed2002

Effect of asymmetric modification on the conformation of ascidiacyclamide analogs.

Ascidiacyclamide (ASC), cyclo(-Ile1-Oxz2-d-Val3-Thz4-)2 (Oxz=oxazoline and Thz=thiazole) has a C2-symmetric sequence, and the relationships between its conformation and symmetry have been studied. In a previous study, we performed asymmetric modifications in which an Ile residue was replaced by Gly, Leu or Phe to disturb the symmetry [Doi et al. (1999) Biopolymers49, 459-469]. In this study, the modifications were extended. The Ile1 residue was replaced by Gly, Ala, aminoisobutyric acid (Aib), Val, Leu, Phe or d-Ile, and the d-Val3 residue was replaced by Val. The structures of these analogs were analyzed by X-ray diffraction, 1H NMR and CD techniques. X-Ray diffraction analyses revealed that the [Ala1], [Aib1] and [Phe1]ASC analogs are folded, whereas [Val1]ASC has a square form. These structures are the first examples of folded structures for ASC analogs in the crystal state and are similar to the previously reported structures of [Gly1] and [Phe1]ASC in solution. The resonances of amide NH and Thz CH protons linearly shift with temperature changes; in particular, those of [Aib1], [d-Ile1] and [Val3]ASCs exhibited a large temperature dependence. DMSO titration caused nonlinear shifts of proton resonances for all analogs and largely affected [d-Ile1] and [Val3]ASCs. A similar tendency was observed upon the addition of acetone to peptide solutions. Regarding peptide concentration changes, amide NH and Thz CH protons of [Gly1]ASC showed a relatively large dependence. CD spectra of these analogs indicated approximately two patterns in MeCN solution, which were related to the crystal structures. However, all spectra showed a similar positive Cotton effect in TFE solution, except that of [Val3]ASC. In the cytotoxicity test using P388 cells, [Val1]ASC exhibited the strongest activity, whereas the epimers of ASC ([d-Ile1] and [Val3]ASCs), showed fairly moderate activities.

Amino Acid Substitution↗
PubMed2002

Hepatocyte growth factor in cerebrospinal fluid in neurologic disease.

OBJECTIVE: To investigate hepatocyte growth factor (HGF) concentration in cerebrospinal fluid (CSF) in neurologic disease. MATERIALS AND METHODS: We determined CSF concentration of HGF with human-HGF-specific enzyme-linked immunosorbent assays (ELISA) in 121 patients: Alzheimer's disease (AD) (33), amyotrophic lateral sclerosis (ALS) (10), Parkinson's disease (PD) (5), progressive supranuclear palsy (PSP) (3), spinocerebellar degeneration (7), acute disseminating encephalomyelitis (ADEM) (6), human T-lymphotropic virus-1 (HTLV-1)-associated myelopathy (HAM) (6), multiple sclerosis (MS) (7), aseptic meningitis (AM) (12), and peripheral neuropathy and myopathy as control diseases (32). RESULTS: HGF concentrations in CSF were significantly higher with diseases of the central nervous system (CNS) than control diseases and were slightly higher with AD than other neurodegenerative diseases. Values were highest with ADEM but decreased during corticosteroid treatment. We found no relationship between HGF in CSF and CSF cells or protein, immunoglobulin index, or Q albumin. CONCLUSION: It is suggested that high concentrations of HGF in CSF may be partially related to CNS pathology, especially to demyelinating disease.

Adult↗
PubMed2002

Altered sarcoplasmic reticulum function in rat diaphragm after high-intensity exercise.

The present study examined the effects of acute high-intensity exercise on Ca(2+) uptake and release rates and Ca(2+)-adenosine triphosphatase (ATPase) activity of the sarcoplasmic reticulum (SR) from the costal diaphragm. The rats were run on a treadmill at an estimated requirement of 100% of maximal O2 consumption until fatigued (average time to exhaustion: 4.79 min). Muscle lactate and inorganic phosphate after exercise were increased by 65% (P < 0.05) and 35% (P < 0.05), respectively. With exercise, Ca(2+) uptake and release, which were detected in homogenates using the Ca(2+) fluorescent dye indo-1, were decreased by 24% (P < 0.05) and 22% (P < 0.05), respectively. The reduction in Ca(2+) uptake was paralleled by decreased activity of SR Ca(2+)-ATPase in both the absence and presence of Ca(2+) ionophore. These findings demonstrate that, in the diaphragm as well as in the locomotor muscles that have been explored in previous studies, the attenuations of the SR function is brought about by acute high-intensity exercise. These changes in the SR of the diaphragm may contribute, at least in part, to deteriorations in exercise tolerance and work productivity resulting from repetitive physical activities.

Animals↗
PubMed2002

Prostaglandin E2 down-regulates viable Bacille Calmette-Guérin-induced macrophage cytotoxicity against murine bladder cancer cell MBT-2 in vitro.

The regulatory effect of prostaglandin (PG) E2 and a cyclooxygenase (COX) inhibitor on Bacille Calmette-Guérin (BCG)-induced macrophage cytotoxicity in a bladder cancer cell, MBT-2, was studied in vitro. BCG stimulated thioglycollate-elicited murine peritoneal exudate cells (PEC) to induce cytotoxic activity and to produce cytokines such as interferon (IFN)-gamma, tumour necrosis factor (TNF)-alpha and PGE2. NS398, a specific COX-2 inhibitor, and indomethacin (IM), a COX-1 and COX-2 inhibitor, enhanced viable BCG-induced cytotoxic activity and IFN-gamma and TNF-alpha production of PEC. However, NS398 and IM did not enhance these activities induced by killed BCG. Enhanced cytotoxicity was mediated by increased amounts of IFN-gamma and TNF-alpha. Exogenous PGE2 reduced cytotoxic activity and IFN-gamma and TNF-alpha production of PEC. These results suggest that PGE2 produced by BCG-activated macrophages has a negative regulatory effect on the cytotoxic activity of macrophages. Accordingly, a PG synthesis inhibitor may be a useful agent to enhance BCG-induced antitumour activity of macrophages.

Animals↗
PubMed2002

Immunohistochemical detection of 8-hydroxydeoxyguanosine, a marker of oxidative DNA damage, in human chronic cholecystitis.

AIMS: Recent studies suggest that oxidative DNA damage induced during chronic inflammation may play a role in carcinogenesis in some organs. Although gallbladder carcinomas are frequently observed with a background of chronic cholecystitis, little is known about oxidative DNA damage in chronic cholecystitis. The aims of this study were to investigate the expression of 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage, in normal and chronically inflamed human gallbladder mucosa and compare its expression with clinicopathological findings. METHODS AND RESULTS: 8-OHdG expression was immunohistochemically examined using a monoclonal antibody against 8-OHdG in human gallbladder specimens. In normal gallbladder (n=5), no 8-OHdG expression was observed. In contrast, nuclear expression of 8-OHdG was detected in 28 of 31cases (90.3%) in gallbladder epithelial cells with chronic cholecystitis. The positive cells were predominantly observed in the areas of active inflammation with prominent cell infiltration. Quantitative analysis revealed that the number of 8-OHdG+ cells (labelling index) significantly (rs=0.671, P < 0.05) correlated with the degree of the activity of mucosal inflammation, while gender, age, and the presence of gallstones did not influence the index. CONCLUSIONS: Oxidative DNA damage is common in chronic cholecystitis, suggesting a possible link between chronic inflammation and gallbladder carcinogenesis.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2002

Inflammatory change in the upper joint space in temporomandibular joint with internal derangement on gadolinium-enhanced MR imaging.

The object of this study was to clarify the relationship between gadopentetate dimeglumine (Gd-DTPA) contrast enhancement of the upper joint space and the severity of internal derangement of the temporomandibular joint (TMJ). Fifty patients with 63 painful TMJs underwent 1.5T MR imaging with T1-weighted images before and after an intravenous injection of Gd-DTPA with or without fat suppression. The relationship was investigated between the contrast enhancement at the upper joint space and disc position, disc morphology or bone morphology. Of the 63 joints, a significant contrast enhancement in the upper joint space was detected in 32 joints. There was a significant high incidence of anterior disc displacement without reduction in the contrast-enhancement positive group compared to the negative group (P = 0.021), but there was no significant difference for disc morphology (P = 0.094) and bone morphology (P = 0.384). Gd-DTPA enhanced MR imaging may potentially have diagnostic value for internal derangements of TMJs.

Adolescent↗
PubMed2002

Gastric mucosal density of Helicobacter pylori estimated by real-time PCR compared with results of urea breath test and histological grading.

The accuracy of the urea breath test (UBT) and histological grading for estimation of the density of Helicobacter pylori in gastric mucosa is not known. Real-time (TaqMan) PCR was used to estimate the total number of H. pylori genomes in biopsy samples. These values were compared with those obtained by the UBT and the histological grade obtained by the Sydney system. The UBT and endoscopy with antral and corporal biopsies were performed in 88 consecutive untreated patients with dyspepsia. Bacterial culture and the rapid urease test were done with fresh biopsy materials. TaqMan PCR and histological examination were done on serial paraffin sections of the biopsy samples. Of the five methods tested, TaqMan PCR had the highest sensitivity and specificity (both 100%) in the diagnosis of H. pylori infection. The mean density of H. pylori genomes for pairs of biopsy samples from individual patients was compared with the individual values obtained by the UBT; correlation between the results was significant. The density of H. pylori genomes was higher in histological grades 1, 2 and 3 than in grade 0, without significant differences between adjacent grades from 1 to 3. These results suggest that the severity of H. pylori infection of the stomach can be estimated by the UBT and that histopathologists might state whether the organism is present or absent, rather than making a quantitative statement as recommended in the Sydney system.

Biopsy↗
PubMed2002

Bonding of self-etch and total-etch adhesives to carious dentin.

Carious dentin is partially demineralized and contains mineral crystals in the tubules. This may permit the deeper etching of intertubular dentin but prevent resin tag formation during bonding. We hypothesize that resin adhesives will produce lower bond strengths to caries-infected and caries-affected dentin compared with normal dentin. We tested this by measuring the microtensile bond strength of a total-etch adhesive and an experimental self-etching adhesive (ABF) to caries-infected, caries-affected, and sound dentin and by correlating those results with ultrastructural observations. The bond strengths of both adhesives to sound dentin were significantly (p < 0.05) higher than those to caries-affected dentin, which, in turn were significantly (p < 0.05) higher than those to caries-infected dentin. For both adhesives, hybrid layers in caries-affected dentin were thicker but more porous than those in sound dentin. The lower bond strengths may be due to the lower tensile strength of caries-affected dentin. Clinically, this may not be a problem, since such lesions are normally surrounded by normal dentin or enamel.

Acid Etching, Dental↗
PubMed2002

Glucose-6-phosphate dehydrogenase in rat lung alveolar epithelial cells. An ultrastructural enzyme-cytochemical study.

Glucose-6-phosphate dehydrogenase (G6PD) is the key enzyme of the pentose phosphate pathway in carbohydrate metabolism, and it plays an important role in cell proliferation and antioxidant regulation within cells in various organs. Although marked cell proliferation and oxidant/antioxidant metabolism occur in lung alveolar epithelial cells, definite data has been lacking as to whether cytochemically detectable G6PD is present in alveolar epithelial cells. The distribution pattern of G6PD within these cells, if it is present, is also unknown. The purpose of the present study was to investigate the subcellular localization of G6PD in alveolar cells in the rat lung using a newly-developed enzyme-cytochemistry (copper-ferrocyanide) method. Type I cells and stromal endothelia and fibroblasts showed no activities. Electron-dense precipitates indicating G6PD activity were clearly visible in the cytoplasm and on the cytosolic side of the endoplasmic reticulum of type II alveolar epithelial cells. The cytochemical controls ensured specific detection of enzyme activity. This enzyme may play a role in airway defense by delivering substances for cell proliferation and antioxidant forces, thus maintaining the airway architecture.

Animals↗