Search PubMed⌕ Search

Biomedical subjects

S Yamada

Publications and source records attributed to S Yamada.

At least 559 records · Page 31Linked to original sources

Prevention strategy for vibration hazards by portable power tools, national forest model of comprehensive prevention system in Japan.

In the 1950s, the introduction of portable power tools into the production process of many industries began on a large scale around the world and resulted in many cases of occupational vibration syndrome after the 1960s. There was an urgent world wide need to undertake preventive steps, medical assessment and therapy. At the end of 1964, our investigation began in Japanese national forests, and then in mines and stone quarries. The Japanese Association of Industrial Hygiene established a "Committee for Local Vibration Hazards" (1965), and many researchers in the medical and technological fields joined this Committee. After 10 years, a comprehensive system for the prevention of vibration syndrome was established in the national forestry. It consists of 1) improvements in vibrating tools, 2) hygienic regulation of operation time with an alternative working system, 3) health care system involving early medical checks, early therapy and age limitations in operation of vibrating tools, 4) protection against cold in the workplace and while commuting, and 5) education and training for health and safety. The prevention strategy for vibration syndrome in our national forests is to establish a comprehensive prevention system in cooperation among researchers in the medical and technological fields, workers and administration. The Ministry of Labor presented that strategy as good model of prevention for other industries (1976). New designs for this model were developed and adapted according to the special conditions of each industry. Thus comprehensive system for prevention of vibration syndrome developed successfully from the late 1970s to 1980s in Japan.

Forestry↗

[Degenerative dementia of the oldest old].

We investigated seven brains from patients 99-105 years of age with a clinical diagnosis of Alzheimer-type dementia (ATD). The pathological findings were as follows. 1) These cases could be divided into two groups: cases with localized cortical atrophy in the medial part of the temporal lobe, and a case with diffuse atrophy in the cerebral cortex. Atrophied cortex in both groups showed laminar degeneration consisting of neuronal loss, neuropil loosening and astrocytosis resulting in fibrillary gliosis, which was particularly marked in the 2nd and 3rd layers of the cerebral cortex. In contrast, the structure of the six cortical layers was preserved when there was no laminar degeneration. Laminar degeneration correlated with cortical atrophy. 2) Cases with localized atrophy were further divided into two groups: group 1 (4 cases) showed small numbers of senile plaques (SPs) and large numbers of neurofibrillary tangles (NFTs' in CA1 of the hippocamupus, subiculum, and parahippohcampul gyrus, while group 2 (2 cases) showed widespread and numerous SPs and NFTs in the cerebral cortex. The distribution of SPs and NFTs in group 2 was similar to that of the case (group 3) with diffuse cortical atrophy. It was considered that group 2 was limbic type ATD and that group 3 was neocortical type ATD, because both groups met our pathological diagnostic criteria ATD. In contrast, group 1 could not be regarded as ATD because the numbers of SPs and NFTs were below those found in ATD, even though this group showed laminar degeneration the same as that of groups 2 and 3. It therefore is likely that group 1 is a unique type of degenerative dementia, pathogenetically different from ATD.

Aged↗

Evaluation of antifungal activity of an antifungal drug by in vitro simulation of in vivo pharmacokinetics of the drug against fungal hyphal growth.

An automatic drug concentration simulator (DCS) has been developed and its applicability has been demonstrated by in vitro simulation of the human plasma concentration-time curve of fluconazole (FLCZ) against hyphal growth of Candida albicans and Aspergillus fumigatus. The response of hyphal growth to FLCZ was continually monitored and analyzed using an automatic hyphal growth analyzing system (Bio-Cell Tracer). The simulated concentration of FLCZ by DCS was confirmed by HPLC. The DCS assay was reproducible with a mean coefficient of variation (C.V., n=3) of 5.38 %. When the growth of C. albicans hyphae was tested, there was a lag of onset of FLCZ effect between the time when FLCZ concentration became maximal (C MAX, 7.95 microg/ml ) and the point at which hyphal growth ceased. In contrast, FLCZ was found inactive against A. fumigatus. The newly devised technique could provide clinicians with important information in determining optimal dosing regimens for antifungal drugs.

Antifungal Agents↗

Expression of the mismatch repair gene hMSH2 in sporadic colorectal cancer.

At least four genes involved in DNA mismatch repair (MMR), hMSH2, hMLH1, hPMS1 and hPMS2, have been cloned and characterized. These genes have been demonstrated to be altered in the germline of patients with hereditary non-polyposis colorectal cancer (HNPCC). HNPCC is an autosomal dominant disease characterized by a preponderance of proximal colon, young age of onset, increased multiplicity, and improved stage-specific survival. In this study, we examined the expression of hMSH2 protein in sporadic colorectal cancer (CRC). As a result, the frequency of right-sided CRC and multiple CRCs were significantly higher in the patients with hMSH2-negative CRC than in those with hMSH2-positive CRC. The rate of p53 positivity was significantly lower in the hMSH2-negative tumours than that in the hMSH2-positive tumours. The disease-free survival rate tended to be higher in the patients with hMSH2-negative CRC than in the patients with hMSH2-positive CRC. Our findings suggest that both the clinicopathological and biological features of hMSH2-negative sporadic CRC seemed to be similar to those of HNPCC. To clarify the mechanism of carcinogenesis in HNPCC and sporadic CRC, further investigations of genetic alterations caused by MMR genes will be needed.

Adult↗

Functional MR imaging of cortical activation of the cerebral hemispheres during motor tasks.

PURPOSE: We used functional MR imaging to evaluate cortical activation in the precentral, central, and postcentral regions of the contralateral and ipsilateral cerebral hemispheres during left- and right-handed motor tasks. METHODS: Ten healthy right-handed volunteers were studied with echo-planner MR imaging (1.5 T) while performing alternating finger apposition tasks with both hands. During the hand tasks, the areas of activated pixels were compared between subregions (precentral, central, and postcentral) of the contralateral and ipsilateral sensorimotor cortex. RESULTS: The activated area of the contralateral sensorimotor cortex was significantly larger than that of the ipsilateral cortex during tasks with either hand, whereas the ipsilateral activated area was significantly larger during the left-handed task than during the right-handed task. Ipsilateral activation was greatest in the precentral region, less in the central region, and least prominent in the postcentral region. CONCLUSIONS: Our results confirmed those of previous investigators that ipsilateral activation is more pronounced during left-sided movements than during right-sided movements. The variation in activation of the precentral, central, and postcentral subregions suggests different roles of the ipsilateral and contralateral hemispheres during motor tasks.

Adult↗

[New methods for measuring atlanto-axial vertical subluxation in rheumatoid arthritis by MR imaging].

We proposed two new methods of measuring atlanto-axial vertical dislocation in rheumatoid arthritis by MR imaging. One is the distance from the subdental synchondrosis of the axis to the diameter of the ring of the atlas. The other is the distance from the midpoint of the anteroposterior ends of the inferior margin of the axis to the diameter of the ring of the atlas. Values were also determined by the Ranawat method and the Redlund-Johnell method. There was good correlation between values determined by the new methods and those determined by the Ranawat method and Redlund-Johnell method.

Adolescent↗

Lesion-to-background ratio in nonattenuation-corrected whole-body FDG PET images.

UNLABELLED: The purpose of this study was to compare the diagnostic efficacy of attenuation-corrected and nonattenuation-corrected whole-body 18F-fluorodeoxyglucose (FDG) PET images to determine an adequate method that can semiquantitatively evaluate nonattenuation-corrected images. METHODS: Whole-body PET studies were performed in 24 fasting patients with various tumors (lung cancers, n = 18; mediastinal tumors, n = 4; breast cancers, n = 2) 30-40 min after a bolus injection of 18F-FDG. Transmission scans followed emission data acquisition. Reconstructed attenuation-corrected and uncorrected images were displayed simultaneously and the relative FDG uptake in lesions and corresponding background areas was evaluated by the region of interest method. Both types of images were also compared with X-CT scans and conventional nuclear medicine scans for diagnostic efficacy. RESULTS: Attenuation-corrected and uncorrected images were found to be equally sensitive for detecting lesions. There was a strong linear correlation between lesion-to-background (L/B) ratios calculated on attenuation-corrected and uncorrected images (r = 0.98; p < 0.001). Significant differences in L/B ratios between attenuation-corrected and uncorrected images were present in only 6 of 55 lesions (11%). Standardized uptake ratios (SURs) in attenuation-uncorrected images did not correlate with SURs in attenuation-corrected images nor with L/B ratios in uncorrected images. CONCLUSION: The efficacy of attenuation-uncorrected FDG PET images in evaluating tumors is similar to that using attenuation-corrected images. Uncorrected images provide not only clinically useful but also quantitative information equivalent to that provided by attenuation-corrected images. However the L/B ratio is the only available index that can be used for quantification of uncorrected images.

Breast Neoplasms↗

[Comparison of the vascular effects of propofol and those of thiopental in patients under cardiopulmonary bypass].

The effects of propofol (1 mg.kg-1) and thiopental (2.5 mg.kg-1) on the vascular smooth muscle were investigated in 10 cardiac patients on cardiopulmonary total bypass using a constant perfusion flow. Radial mean arterial blood pressure (mAP) decreased to 85 +/- 5% (P < 0.01, vs preinjection) in the post-injection late phase (2-3 min) after propofol, and to 90 +/- 6% (P < 0.01) after thiopental. MAP after thiopental showed a transient initial increase to 115 +/- 8% (P < 0.01) in the post-injection early phase (-1 min). Skin blood flow (SBF) in the middle finger-tip increased to a peak of 450 +/- 120% (P < 0.01) in the post-injection late phase after propofol, and to 240 +/- 60% (P < 0.05) after thiopental. The increase in SBF after propofol was greater than that after thiopental (P < 0.05). The decrease in mAP and the increase in SBF under the constant perfusion flow are considered mainly due to a direct drug action of dilating peripheral vessels. In conclusion, this in vivo human study suggests that propofol (1 mg.kg-1) causes more potent vasodilatation in the peripheral vessels than thiopental (2.5 mg.kg-1).

Aged↗

[Long-term results and quality of life of hemi-Kock orthotopic ileal neobladder after radical cystectomy].

We analyzed the long-term results and the quality of life in patients who received orthotopic lower urinary tract reconstruction using the Kock ileal neobladder. Between July 1990 and October 1993, 37 consecutive patients including 2 females received orthotopic hemi-Kock neobladder after radical cystectomy. In these patients, we analyzed the urinary continence, complications and urethral recurrence, and performed a questionnaire survey by mail. Good continence all day had been achieved in 71% of the patients 4 years after surgery. The rate of the pouch-related complications requiring reoperation was 27%. There was no urethral recurrence. Compared with preoperative conditions, 42% were not satisfied with urination. In these dissatisfied patients, the need to use pads in the daytime, sensation of residual urine and weak urine stream were significantly more frequent than in satisfied patients. In summary, the rate of complications was higher than that of other methods. However, the Kock orthotopic ileal neobladder is a stable procedure providing good function over the long-term.

Adult↗

Hepatocyte growth factor is a potent trigger of neutrophil adhesion through rapid activation of lymphocyte function-associated antigen-1.

Recruitment of neutrophils into tissue occurs in several pathologic processes such as inflammation, atherosclerosis, thrombosis, and ischemia. In inflammation, the adherence of neutrophils to the endothelium depends on neutrophil integrins. Integrin-mediated adhesion is tightly regulated, ie, integrins do not function if neutrophils are not triggered by certain activation stimuli. We investigated the role of hepatocyte growth factor (HGF) in the adhesion of neutrophils to endothelial cells in inflammation. Our results showed that (a) HGF induced not only lymphocyte function-associated antigen-1 (LFA-1)-mediated adhesion of neutrophils to endothelial cells but also transmigration of neutrophils in a concentration-dependent manner; (b) HGF functionally transformed neutrophil integrin LFA-1 to active form and reduced surface L-selectin expression level; (c) HGF induced F-actin polymerization and cytoskeletal rearrangement within seconds; (d) genistein, a tyrosine kinase inhibitor, as well as wortmannin, a phosphoinositide 3 (PI 3)-kinase inhibitor, inhibited both F-actin polymerization and LFA-1-mediated adhesion of neutrophils to endothelial cells; and (e) neutrophils in cutaneous inflamed tissue highly expressed HGF and serum levels of HGF were elevated in patients with Behçet's disease, which is associated with neutrophilic vasculitis and marked neutrophil accumulation. Our results indicate that HGF plays a pivotal role in integrin-mediated adhesion and transmigration of neutrophils to sites of acute inflammation through cytoskeletal rearrangement activated by tyrosine kinase and PI 3-kinase signaling.

Actins↗

[Hepatic clearance of 99mTc-GSA in cases of postoperative biliary atresia--a retrospective comparison with hepatic clearance of 99mTc-PMT].

There are a few reports about usefulness of 99mTc-GSA liver scintigraphy (GSA imaging) for the evaluation of postoperative state of biliary atresia. However, comparison of significance for the disease between GSA imaging and 99mTc-PMT hepatobiliary imaging have not been reported. Fifty-six GSA imagings for 41 postoperative biliary atresia patients were reviewed and their scintigraphic findings and the functional parameters were compared with those obtained from 99mTc-PMT hepatobiliary imaging. In quantitative analysis, although the hepatic clearance of both tracers calculated by graphical analysis (Patlak plot) were well correlated in most cases, a discrepancy was observed in several cases with jaundice. The authors conclude that the hepatic clearance of 99mTc-GSA is a more accurate index of the hepatic reserve than that of 99mTc-PMT which can be influenced by hyperbilirubinemia and that the combination of both examinations is helpful to evaluate development of liver injury in postoperative biliary atresia patients.

Biliary Atresia↗

Osteoclastic resorption of biphasic calcium phosphate ceramic in vitro.

Neonatal rabbit bone cells were cultured for 1 and 4 days on biphasic calcium phosphate ceramic specimens to study the osteoclastic resorption of the ceramic. Scanning electron microscopic studies after removal of stromal cells with pronase E and EDTA revealed many osteoclast-associated lacunae on the ceramic surface. The degraded crystals inside the lacunae appeared to have been dissolved by acids. Cellular degradation of the ceramic was clearly due to the extracellular process characteristic of osteoclastic resorption.

Animals↗

Implication of Video Assisted Thoracoscopic Surgery in the Diagnosis of Pulmonary Metastasis of Breast Cancer.

PURPOSE: To determine pulmonary metastasis, video assisted thoracoscopic surgery (VATS) was performed on the patients who had undergone breast cancer aurgery. PATIENTS AND METHODS: Nineteen patients with a history of breast cancer underwentVATS, because of subsequent abnormal pulmonary shadows on chest computed tomograms (CT). All patients were suspected to have pulmonary metastasis from breast cancer. RESULTS: The VATS procedure showed 10(52%) patiens to have pulmonary metastasis, but, 9(48%) had primary lung cancers or benign lesions. In the patients of pulmonary metastasis, 7 had nodular lesions (5 had a single nodule and 2 had two nodules with a median diameter of 8.5 mm), and 3 patients had pleural dissemination. The follow-up period of the patients with pulmonary metastasis ranged from 3 to 28 months. Three patients died of brain metastasis and respiratory failure, 3 suffered recurrence and 4 were free from disease after VATS. CONCLUSION: VATS was useful for distinguishing small metastatic lesions from other diseases and a minimally invasive surgical approach in the follow-up of breast cancer patients suspected of pulmonary metastasis.

Journal Article↗

Novel tetrasaccharides isolated from squid cartilage chondroitin sulfate E contain unusual sulfated disaccharide units GlcA(3-O-sulfate)beta1-3GalNAc(6-O-sulfate) or GlcA(3-O-sulfate)beta1-3GalNAc.

We previously isolated novel tetrasaccharides containing 3-O-sulfated glucuronic acid from king crab cartilage chondroitin sulfate K and demonstrated that the disaccharide units containing 3-O-sulfated glucuronic acid were decomposed by chondroitinase ABC digestion (Sugahara, K., Tanaka, Y., Yamada, S., Seno, N., Kitagawa, H., Haslam, S. M., Morris, H. R., and Dell, A. (1996) J. Biol. Chem. 271, 26745-26754). The findings indicated the necessity to re-evaluate the disaccharide compositions of chondroitin sulfate preparations purified from other biological sources and analyzed using the above enzyme. In this study, to evaluate squid cartilage chondroitin sulfate E a series of even-numbered oligosaccharides were isolated after exhaustive digestion with sheep testicular hyaluronidase and subsequent fractionation by gel chromatography. The tetrasaccharide fraction was subfractionated by high performance liquid chromatography on an amine-bound silica column. Systematic structural analysis of five major fractions, h, l, m, n, and q, by fast atom bombardment mass spectrometry, enzymatic digestions in conjunction with capillary electrophoresis, and 500-MHz 1H NMR spectroscopy revealed one disulfated, three trisulfated, and one tetrasulfated tetrasaccharide structure: fraction h, GlcAbeta1-3GalNAc(4S)beta1-4GlcAbeta1-3GalNAc(4S); fraction l, GlcA(3S)beta1-3GalNAc(6S)beta1-4GlcAbeta1-3GalNAc(4S); fraction m, GlcA(3S)beta1-3GalNAc(4S)beta1-4GlcAbeta1-3GalNAc(4S); fraction n, GlcAbeta1-3GalNAc(4S,6S)beta1-4GlcAbeta1-3GalNAc(4S); and fraction q, GlcA(3S)beta1-3GalNAc(4S,6S)beta1-4GlcAbeta1-3GalNAc(4S), where 3S, 4S, and 6S represent 3-O-, 4-O- and 6-O-sulfate, respectively. The structures found in fractions h and m as well as the unsaturated counterpart of that found in fraction n have been reported, whereas those in fractions l and q are novel in that they contained unusual disulfated and trisulfated disaccharide units where GlcA(3S) is directly linked to GalNAc(6S) and GalNAc(4S,6S), respectively. These novel tetrasaccharide sequences are distinct from those found in other chondroitin sulfate isoforms and may play key roles in the biological functions and activities of chondroitin sulfate E not only from squid cartilage but also from mammalian cells and tissues.

Animals↗

In vivo metabolism of 24R,25-dihydroxyvitamin D3: structure of its major bile metabolite.

In vivo metabolism of 24R,25-dihydroxyvitamin D3 (24,25-(OH)2D3) in female dogs has been studied thoroughly, and its major bile metabolite identified. After single oral administration of 24,25-(OH)2 [6,19,19-3H]D3 the plasma concentrations of radioactive metabolites were monitored for 504 h, and the metabolites in the bile collected and analyzed. The concentration of 24,25-(OH)2D3 in plasma reached a maximum after 6 h and decayed in two distinct phases; a fast-phase with a half-life of 17 h, followed by a slow-phase with a 17-day half-life. The area under the concentration/time curve (AUC) was 78-84% (0-504 h). The only detectable metabolite in the plasma was 25-hydroxy-24-oxovitamin D3 whose AUC was less than 5%. At 504 h, about 50% of administered radioactivity has been excreted, of which about 90% was found in the feces, indicating most of the administered 24,25-(OH)2D3 to be excreted in bile. A major metabolite, which constituted 23% of the total bile radioactivity at 504 h, was found in the bile. This metabolite was efficiently deconjugated by beta-glucuronidase to afford an aglycone which was identified as 23S,25-dihydroxy-24-oxovitamin D3 (23S,25-(OH)2-24-oxo-D3), by co-chromatography on HPLC with synthetic standards. The glucuronide was isolated from the bile of dogs given large doses of 24,25-(OH)2D3, and the structure determined being 23-(beta-glucuronide) of 23S,25-(OH)2-24-oxo-D3, by analyzing its negative ion mass spectrum and the positive ion mass spectrum of its derivatives. Thus it was concluded that, in dogs, 24,25-(OH)2D3 is a long lasting vitamin D metabolite, is mainly excreted in bile when metabolized to 23S,25-(OH)2-24-oxo-D3 and is conjugated at 23-OH as glucuronide.

24,25-Dihydroxyvitamin D 3↗

1alpha,25-dihydroxyvitamin D3-24-hydroxylase (CYP24) hydroxylates the carbon at the end of the side chain (C-26) of the C-24-fluorinated analog of 1alpha,25-dihydroxyvitamin D3.

The sequential oxidation and cleavage of the side chain of 1alpha, 25-dihydroxyvitamin D3 (1alpha,25(OH)2D3) initiated by the hydroxylation at C-24 is considered to be the major pathway of this hormone in the target cell metabolism. In this study, we examined renal metabolism of a synthetic analog of 1alpha,25(OH)2D3, 24, 24-difluoro-1alpha,25-dihydroxyvitamin D3 (F2-1alpha,25(OH)2D3), C-24 of which was designed to resist metabolic hydroxylation. When kidney homogenates prepared from 1alpha,25(OH)2D3-supplemented rats were incubated with F2-1alpha,25(OH)2D3, it was mainly converted to a more polar metabolite. We isolated and unequivocally identified the metabolite as 24,24-difluoro-1alpha,25,26-trihydroxyvitamin D3 (F2-1alpha,25,26(OH)3D3) by ultraviolet absorption spectrometry, frit-fast atom bombardment liquid chromatography/mass spectroscopy analysis, and direct comparison with chemically synthesized F2-1alpha,25,26(OH)3D3. Metabolism of F2-1alpha,25(OH)2D3 into F2-1alpha,25,26(OH)3D3 by kidney homogenates was induced by the prior administration of 1alpha,25(OH)2D3 into rats. The C-24 oxidation of 1alpha,25(OH)2D3 in renal homogenates was inhibited by F2-1alpha,25(OH)2D3 in a concentration-dependent manner. Moreover, F2-1alpha,25,26(OH)3D3 was formed in ROS17/2.8 cells transfected with a plasmid expressing 1alpha,25(OH)2D3-24-hydroxylase (CYP24) but not in the cells transfected with that expressing vitamin D3-25-hydroxylase (CYP27) or containing inverted CYP27 cDNA. These results show that CYP24 catalyzes not only hydroxylation at C-24 and C-23 of 1alpha,25(OH)2D3 but also at C-26 of F2-1alpha,25(OH)2D3, indicating that this enzyme has a broader substrate specificity of the hydroxylation sites than previously considered.

Animals↗