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Biomedical subjects

H Yoshida

Publications and source records attributed to H Yoshida.

At least 361 records · Page 20Linked to original sources
PubMed2000

IR Spectra of CH(4) Physisorbed on an Active Carbon at Low Temperature.

The IR absorption band of methane adsorbed on an active carbon was obtained at 153 K. The IR nu(1) band of methane (inherently IR inactive in the gaseous phase) adsorbed on the active carbon was induced by the electric field of surface groups, even though the adsorbent was known to be macroscopically hydrophobic. The source of the electric field was suggested to be a hydrogen-bonding surface carboxyl or phenolic OH group. The strength of the electric field was estimated to be 1.13 x 10(5) esu, although the number of sites bearing an electric field was very small. A strong electric field (1.75 x 10(5) esu) was created on the carbon surface by oxidation, and its origin was suggested to be carbonyl groups. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Histologic improvement of fibrosis in patients with hepatitis C who have sustained response to interferon therapy.

BACKGROUND: Short-term histologic improvement in hepatitis C-related hepatic fibrosis has been noted in studies with more than 2 years of follow-up, but the long-term effects of interferon therapy on hepatic fibrosis remain unclear. OBJECTIVE: To assess changes in hepatic fibrosis after interferon therapy in patients with chronic hepatitis C. DESIGN: Retrospective cohort study. SETTING: 7 university hospitals and 1 national hospital in Japan. PATIENTS: 593 patients with chronic hepatitis C who underwent a paired liver biopsy from 1987 to 1997. Of these, 487 patients received interferon therapy and 106 patients were untreated. INTERVENTION: Patients in the treatment group received a 2- to 6-month course of interferon within 6 months after the initial biopsy. MEASUREMENTS: Fibrosis and inflammatory activity in paired biopsy samples obtained a median of 3.7 years apart (range, 1 to 10 years) were graded by using the criteria of Desmet and colleagues (F0 to F4) and those of the French METAVIR Cooperative Study Group (A0 to A3), respectively. Changes in fibrosis staging and activity scores and yearly rates of fibrosis progression and regression were calculated. RESULTS: 183 of the 487 interferon-treated patients showed a sustained virologic response. Activity grade was unchanged in most of the untreated patients and improved in 89% (CI, 83% to 93%) of patients with a sustained virologic response. A sustained response to interferon was associated with a mean (+/-SE) reduction in fibrosis score of -0.60+/-0.07 at less than 3 years of follow-up and -0.88+/-0.08 at 3 years or more of follow-up. The rate of fibrosis progression was -0.28+/-0.03 unit/y (regression) in patients with sustained response, 0.02+/-0.02 unit/y in patients with nonsustained response (P< 0.001), and 0.10+/-0.02 unit/y in untreated patients. CONCLUSION: Although the time between biopsies partly affected the patient's clinical course, the differences observed here suggest that in patients with chronic hepatitis C, regression of fibrosis is associated with sustained virologic response to interferon therapy.

Adult↗
PubMed2000

Unique clinical characteristics of patients with hepatocellular carcinoma who present with high plasma des-gamma-carboxy prothrombin and low serum alpha-fetoprotein.

BACKGROUND: Although the importance of alpha-fetoprotein (AFP) and des-gamma-carboxy prothrombin (DCP) in the clinical treatment of hepatocellular carcinoma (HCC) has been studied extensively, the authors examined the clinical picture of HCC with regard to the state of these two tumor markers. METHODS: The authors categorized 237 HCC cases into 4 groups according to levels of AFP and DCP: high levels of AFP with low DCP levels, high DCP levels with low AFP levels, high levels of both tumor markers, and low levels of both tumor markers. Comparisons of survival rates were made among these groups using the Kaplan-Meier product limit method, and for other comparisons of clinical parameters the Fisher PSLD test was used. Prognostic significance was tested with the Cox proportional hazards model. RESULTS: The cutoff values were set at 100 ng/mL for AFP and 0.0625 AU/mL for DCP. Forty-eight patients (20.7%) had high levels of AFP and low levels of DCP, 22 (9.3%) had high DCP levels and low levels of AFP, 12 (4.6%) had high levels of both AFP and DCP, and 155 (65.4%) had low levels of both DCP and AFP. Patients with high levels of DCP but low levels of AFP were predominantly male and had large lesions but few nodules. Patients with high levels of both tumor markers had the most discouraging outcome observed in this study (death within 3 years). CONCLUSIONS: Patients with high levels of DCP and low levels of AFP exhibited the unique clinical characteristic of large HCC nodules that were few in number. In addition, it was observed that measurement of both AFP and DCP can predict the survival of patients.

Adult↗
PubMed2000

Increasing the thermal stability of the water-soluble pyrroloquinoline quinone glucose dehydrogenase by single amino acid replacement.

Based on the characterization of a PCR mutation of water-soluble glucose dehydrogenase possessing pyrroloquinoline quinone (PQQ), PQQGDH-B, Ser231Cys, we have constructed a series of Ser231 variants. The replacement of Ser231 to Cys, Met, Leu, Asp, Asn, His, or Lys resulted in an increase in thermal stability. Among these variants, Ser231Lys showed the highest level of thermal stability and also showed high catalytic activity. Considering that Ser231Lys showed more than an 8-fold increase in its half-life during the thermal inactivation at 55 degrees C compared with the wild-type enzyme, and also retained catalytic activity similar to a wild-type enzyme, the application of this mutant enzyme as a glucose sensor constituent may develop into a stable glucose sensor construction.

Journal Article↗
PubMed2000

Assessment of gastric carcinoma risk associated with Helicobacter pylori may vary depending on the antigen used: CagA specific enzyme-linked immunoadsorbent assay (ELISA) versus commercially available H. pylori ELISAs.

BACKGROUND: Previous epidemiologic studies produced inconsistent results when examining the relation between Helicobacter pylori infection and the risk of gastric carcinoma by measuring various anti-H. pylori antibodies. This study investigated the increased risk of cancer by examining different antibodies, including the specific anti-CagA antibody and antibodies from two commercially available kits. METHODS: An ELISA for the detection of serum anti-CagA was established using a recombinant CagA protein that the authors previously reported. Serum anti-CagA titer was determined for 80 patients with gastric carcinoma and 80 gender- and age-matched controls. Two anti-H. pylori antibodies from the commercially available kits HEL-p (Amrad, Kew Vic, Australia) and HM-CAP (Enteric Product Inc., Westbury, NY) were also evaluated. RESULTS: Anti-CagA seropositivity differed significantly between gastric carcinoma patients and controls (92.5% vs. 55.0%; P = 0. 0001), showing an odds ratio of 10.4 (95% confidence interval [CI]: 4.23-29.74). The difference was less prominent for the seropositivity of HEL-p (77.5% vs. 58.8%; P = 0.0139; odds ratio: 2. 38; 95% CI: 1.20-4.82) and insignificant for that of HM-CAP (65.0% vs. 57.5%; P = 0.4325; odds ratio: 1.30; 95% CI: 0.68-2.49). CONCLUSIONS: The current study revealed that the antibody assay system used could be one important factor in the assessment of gastric carcinoma risk for patients with H. pylori.

Adult↗
PubMed2000

DNA damage-induced activation of p53 by the checkpoint kinase Chk2.

Chk2 is a protein kinase that is activated in response to DNA damage and may regulate cell cycle arrest. We generated Chk2-deficient mouse cells by gene targeting. Chk2-/- embryonic stem cells failed to maintain gamma-irradiation-induced arrest in the G2 phase of the cell cycle. Chk2-/- thymocytes were resistant to DNA damage-induced apoptosis. Chk2-/- cells were defective for p53 stabilization and for induction of p53-dependent transcripts such as p21 in response to gamma irradiation. Reintroduction of the Chk2 gene restored p53-dependent transcription in response to gamma irradiation. Chk2 directly phosphorylated p53 on serine 20, which is known to interfere with Mdm2 binding. This provides a mechanism for increased stability of p53 by prevention of ubiquitination in response to DNA damage.

Animals↗
PubMed2000

GATA-1 blocks IL-6-induced macrophage differentiation and apoptosis through the sustained expression of cyclin D1 and bcl-2 in a murine myeloid cell line M1.

Cytokines exert pleiotropic effects on target cells in a manner dependent on the cell type or stage of differentiation. To determine how instinctive cell properties affect biological effects of cytokine, we introduced an erythroid/megakaryocyte lineage-specific transcription factor, GATA-1, into a murine myeloid cell line M1, which is known to undergo macrophage differentiation in response to interleukin 6 (IL-6). Overexpression of GATA-1 changed the phenotype of M1 cells from myeloid to megakaryocytic lineage. Furthermore, GATA-1 blocked both IL-6-induced macrophage differentiation and apoptosis of M1 cells. Although STAT3 is essential for IL-6-induced macrophage differentiation of M1 cells, GATA-1 had little or no effect on tyrosine phosphorylation, DNA binding, and transcriptional activities of STAT3 in Western blot analysis, electropholic mobility shift assay (EMSA), and luciferase assays. During IL-6-induced macrophage differentiation of M1 cells, IL-6 down-regulated cyclin D1 expression and induced p19(INK4D) expression, leading to reduction in cdk4 activities. In contrast, sustained expression of cyclin D1 and a significantly lesser amount of p19(INK4D) induction were observed in IL-6-treated M1 cells overexpressing GATA-1. Furthermore, although bcl-2 expression was severely reduced by IL-6 in M1 cells, it was sustained in GATA-1-introduced M1 cells during the culture with IL-6. Both IL-6-induced macrophage differentiation and apoptosis were significantly abrogated by coexpression of cyclin D1 and bcl-2, whereas overexpressions of cyclin D1 or bcl-2 inhibited only differentiation or apoptosis, respectively. These results suggested that GATA-1 may not only reprogram the lineage phenotype of M1 cells but also disrupt the biologic effects of IL-6 through the sustained expression of cyclin D1 and bcl-2. (Blood. 2000;95:1264-1273)

Animals↗
PubMed2000

The interspinous ligament of the lumbar spine. Magnetic resonance images and their clinical significance.

STUDY DESIGN: A preliminary study of magnetic resonance features of the interspinous ligament in degenerative lumbar spine. OBJECTIVES: To classify the magnetic resonance imaging features of the interspinous ligaments in relation to the patient's age, disc degeneration, and radiographic instability. Magnetic resonance imaging also was correlated with the histologic findings of the interspinous ligaments. SUMMARY OF BACKGROUND DATA: As reported, rupture of the interspinous ligament frequently is found in the degenerative lumbar spine. However, little information is available in the literature on imaging assessment of the interspinous ligament in degenerative lumbar disorders. METHODS: In this study, 24 interspinous ligaments at L1-L2 or L2-L3 from 15 patients with nondegenerated discs were selected to represent normal magnetic resonance features of the interspinous ligament, and 38 patients with the mean age of 49 years underwent functional radiography and magnetic resonance imaging. The magnetic resonance features of the interspinous ligament were classified into five categories according to their signal intensities: Type 1A (low intensity on T1- and T2-weighted images without hypertrophy of the spinal process); Type 1B (same signal pattern as in Type 1A with hypertrophy of spinal process); Type 2 (low intensity on T1- and high intensity on T2-weighted images); Type 3 (high intensity on T1-weighted images); and Type 4 (others). Seven patients with variable patterns of the interspinous ligament were selected to undergo histologic examinations. RESULTS: Of the interspinous ligaments considered normal, 80% were classified as Type 1A. There were 14 Type 1A, 30 Type 1B, 19 Type 2, 16 Type 3, and 20 Type 4 ligaments. The mean age and disc degeneration grade of the patients with the Type 1B ligaments was significantly higher. Instability was found to be associated with Type 2 interspinous ligaments (7 of 19), whereas instability rarely was noted in Types 1A (1 of 14) and 1B (1 of 30) ligaments. The histologic examination revealed that chondrometaplasia and necrotization of fiber bundle predominated in Type 1B, proliferation of cells and vascular invasion in Type 2, fatty degeneration in Type 3 ligaments. CONCLUSIONS: The magnetic resonance imaging characteristics may be helpful in assessing normal or pathologic changes in the interspinous ligaments.

Adolescent↗
PubMed2000

Double trans-chromosomic mice: maintenance of two individual human chromosome fragments containing Ig heavy and kappa loci and expression of fully human antibodies.

The use of a human chromosome or its fragment as a vector for animal transgenesis may facilitate functional studies of large human genomic regions. We describe here the generation and analysis of double trans-chromosomic (Tc) mice harboring two individual human chromosome fragments (hCFs). Two transmittable hCFs, one containing the Ig heavy chain locus (IgH, approximately 1.5 Mb) and the other the kappa light chain locus (Igkappa, approximately 2 Mb), were introduced into a mouse strain whose endogenous IgH and Igkappa loci were inactivated. In the resultant double-Tc/double-knockout mice, substantial proportion of the somatic cells retained both hCFs, and the rescue in the defect of Ig production was shown by high level expression of human Ig heavy and kappa chains in the absence of mouse heavy and kappa chains. In addition, serum expression profiles of four human Ig gamma subclasses resembled those seen in humans. They mounted an antigen-specific human antibody response upon immunization with human serum albumin, and human serum albumin-specific human monoclonal antibodies with various isotypes were obtained from them. These results represent a generation of mice with "humanized" loci by using the transmittable hCFs, which suggest that the Tc technology may allow for the humanization of over megabase-sized, complex loci in mice or other animals. Such animals may be useful not only for studying in vivo functions of the human genome but also for obtaining various therapeutic products.

Animals↗
PubMed2000

Cell cycle arrest enhances the in vitro cellular toxicity of the truncated Machado-Joseph disease gene product with an expanded polyglutamine stretch.

Machado-Joseph disease (MJD) is an inherited neurodegenerative disorder caused by the expansion of the polyglutamine stretch in the MJD gene-encoded protein, ataxin-3. Using a series of deletion constructs expressing ataxin-3 fragments with expanded polyglutamine stretches, we observed aggregate formation and cell death in cultured BHK-21 cells. The cytotoxic effect of N-terminal-truncated ataxin-3 with the expanded polyglutamine tract was enhanced under serum starvation culture, in which cells were arrested in the G(0)/G(1)phase. Coexpression of p21 (waf1/cip1/sdi1), a cyclin-Cdk inhibitor that induced cell cycle arrest in the G(1)phase, also increased the cell death susceptibility produced by the mutant ataxin-3 fragment in BHK-21 cells. The elevated susceptibility to cell death in the G(0)/G(1)phase was confirmed in nerve growth factor-treated, postmitotic neuronal PC12 cells compared with undifferentiated proliferating PC12 cells. These results strongly suggest that the cellular toxicity of truncated ataxin-3 with an expanded polyglutamine stretch is enhanced by cell cycle arrest in the G(0)/G(1)phase. Mutant ataxin-3 may confer a higher susceptibility to cell death on cells in the G(0)/G(1)phase.

Animals↗
PubMed2000

A novel tau mutation (N296N) in familial dementia with swollen achromatic neurons and corticobasal inclusion bodies.

Familial dementia with swollen achromatic neurons and corticobasal inclusion bodies is a neurodegenerative disease that resembles corticobasal degeneration. It is characterized by the presence of abundant neuronal and glial tau protein deposits. Here we describe a novel silent mutation in exon 10 of tau (N296N) in this familial dementia. By exon trapping, the mutation produced an increase in the splicing in of exon 10, indicating that it probably causes disease through an overproduction of four-repeat tau.

Base Sequence↗
PubMed2000

Cytoprotective mechanism of heat shock protein 70 against hypoxia/reoxygenation injury.

The role of heat shock protein 70 (HSP70) in the cytoprotection against hypoxia/reoxygenation injury was examined. Adult rat cardiomyocytes were isolated, subjected to hyperthermia at 42 degrees C for 15 min (heat shock treatment), and then incubated at 37 degrees C for 3 to 24 h (HSP production process). Heat shock treatment increased HSP70 production (80-260% increase); the peak increase was seen after 9 h of HSP production process. Thereafter, the cells were subjected to 120-min hypoxia and 15-min reoxygenation. Heat shock treatment increased the survival of the cells subjected to hypoxia/reoxygenation (1.5-2.5-fold); the maximal cytoprotection was observed after 12 h of HSP production process. Heat shock treatment increased HSP70 content in the nucleus when cells were subjected to 12 h of HSP production process. To examine the role of HSP70 accumulation in the nuclear fraction, the activity of poly(ADP-ribose) synthetase (PARS), which functions in the nucleus and consumes high-energy phosphates excessively in the reoxygenated state, were measured in the cells with heat shock and 12 h of HSP production process. Heat shock treatment attenuated the hypoxia/reoxygenation-induced increase in the PARS activity (50% decrease). Treatment of the cells with 3-aminobenzamide, an inhibitor of PARS, exerted the effects similar to those of heat shock treatment. These results suggest that attenuation of the PARS activity in the nucleus may play an important role in the cytoprotective effect of HSP70 on hypoxia/reoxygenation injury.

Animals↗
PubMed2000

The effect of verbal feedback on motor learning--a PET study. Positron emission tomography.

The purpose of this study was to investigate brain mechanisms underlying feedback effects on motor learning. We measured human brain activity using positron emission tomography (PET) during length-of-line drawing tasks in the presence or absence of verbal feedback, i.e., information on the precision of motor performance. The average error in responses was significantly lower and the percentage of correct responses was significantly higher in the case of tasks with feedback than those in the absence of feedback. The contralateral sensorimotor, premotor, supplementary motor, the right prefrontal, bilateral parietal and temporal, and anterior cingulate cortices, and the left basal ganglia were activated during all the line-drawing tasks. The right lateral prefrontal and occipital cortices and the left basal ganglia exhibited marked increase in activity after learning. The right inferior parietal and the anterior cingulate cortices were activated in the presence of feedback which provided information on how the subjects should correct their performances. The results indicate that these brain areas may play an important role in representing knowledge of results during motor learning and that appropriate feedback may facilitate motor learning.

Adult↗
PubMed2000

A case of primary squamous cell carcinoma of the breast with rapid progression.

Primary squamous cell carcinoma of the breast is a rare disease for which no definite treatment or prognosis has been established. This report describes our experience with one case of primary squamous cell carcinoma of the breast that ended in death after rapid progression. The patient was a 58 year old woman who visited our hospital complaining of a growing tumor and pain in the right breast. Ultrasonographically the tumor consisted of solid tumor and a large cyst. Squamous cell carcinoma was diagnosed by fine-needle aspiration cytology. Neoadjuvant CEF was given, but the tumor continued to grow, so CEF was discontinued after one course and modified radical mastectomy was performed subsequently. There was no evidence of metastasis to lymph nodes. About 5 months post operatively CT of the head and chest X-ray demonstrated metastatic lesions in the brain and lungs. Resection of the cerebral tumor was performed. About 1 month after the operation, however, a new metastatic brain tumor was found and the patient later died.

Breast Neoplasms↗
PubMed2000

Scintigraphic assessment of regional cardiac sympathetic nervous system in patients with single-vessel coronary artery disease.

In coronary artery disease, the cardiac sympathetic nervous system is closely associated with myocardial ischemia. I-123 metaiodobenzylguanidine (MIBG) imaging allows us to assess the cardiac sympathetic nervous system regionally. One-hundred and eleven patients with single-vessel disease underwent regional quantitative analysis of MIBG imaging before successful percutaneous transluminal coronary angioplasty (PTCA), and repeat angiography 6 months after PTCA. Based on the results of the follow-up left ventriculogram, patients were divided into 3 groups: 39 angina pectoris (AP), 48 prior myocardial infarction without asynergy (MI without asynergy) and 24 prior myocardial infarction with asynergy (MI with asynergy). AP and MI without asynergy had significant correlations between uptake parameters and regional washout in the territory of diseased vessels, among which the severity score in AP was the most closely correlated with regional washout (r = 0.79, p < 0.0001). These correlations disappeared in MI with asynergy. To compare regional MIBG parameters in the territory of the diseased vessel as well as in the territories of the other major coronary arteries among the 3 groups, we examined MIBG parameters in 57 patients with left anterior descending artery (LAD) disease selected from among the study patients. Regional washout in the territory of the LAD was significantly higher in the MI without asynergy group than in the other two groups. The left circumflex artery (LCX) region showed significantly reduced MIBG uptake and an increased extent score in the MI with asynergy group compared with the AP group, although only a difference in the extent score existed between the MI with asynergy group and the AP group in the right coronary artery (RCA) region. In addition, the global ejection fraction before PTCA showed a significant negative correlation with each regional washout rate. In this way, regional quantitative analysis of MIBG imaging can detect the regional differences in the cardiac sympathetic nervous system in coronary artery disease, which may be associated with the degree of regional left ventricular dysfunction due to myocardial ischemia.

3-Iodobenzylguanidine↗
PubMed2000

Axillocoronary bypass in a patient with a severely atherosclerotic aorta.

We report an axillocoronary bypass in a 70-year-old man with a severely atherosclerotic, calcified aorta. The patient had insulin-dependent diabetes mellitus and had 2-vessel coronary artery disease with a lesion in the left main coronary artery. He underwent an axillary artery-circumflex artery bypass with a saphenous vein graft combined with a bypass of the left internal thoracic artery to the left anterior descending artery without aortic cross-clamping. An easy, safe procedure, axillocoronary bypass is a viable option in coronary artery bypass grafting for patients with severely atherosclerotic, calcified aortas.

Aged↗
PubMed2000

Association of bone mineral density with polymorphism of the human calcium-sensing receptor locus.

A strong correlation between bone mass and genetic factors has been shown in twins and family studies. Some of the genes involved would regulate bone metabolism, bone formation, and resorption, all processes that determine bone mass. One candidate genes, calcium-sensing receptor (CASR) in the parathyroid gland, regulates calcium homeostasis by sensing decreases in extracellular calcium level and effecting an increase in secretion of parathyroid hormone (PTH) and calcium (Ca) reabsorption in the kidney. We have investigated a possible association between the CA-repeat polymorphism at the human CASR gene locus and the bone mineral density (BMD) of radial bone in 472 postmenopausal Japanese women. Genotypes were classified into nine groups according to the number of CA repeats present, from 20 to 12. BMD was expressed as the adjusted BMD, which was the body mass index (BMI), and age-adjusted average BMD. The 247 women who had an A3 allele (228 bp, containing 18 repeats of CA) had significantly lower adjusted BMD (mean +/- SD: 0.303 +/- 0.059 versus 0.316 +/- 0.063 g/cm(2); P = 0.0308) than the participants (n = 201) who did not carry an allele of that size. This result suggests that genetic variation at the CASR gene locus is associated with some determinants for BMD in postmenopausal women.

Aged↗