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Biomedical subjects

T Sakurai

Publications and source records attributed to T Sakurai.

At least 73 records · Page 4Linked to original sources
PubMed2001

Prevalence of Helicobacter pylori infection and correlation between severity of upper gastrointestinal lesions and H. pylori infection in Japanese patients with Crohn's disease.

BACKGROUND: The prevalence of Helicobacter pylori infection in Crohn's disease (CD) patients was investigated to determine whether the presence and severity of gastroduodenal lesions were related to H. pylori infection. METHODS: Infection rates were compared between CD group (n = 90) and the control group (n = 525). Correlations between endoscopically detected lesions and H. pylori positive rates were investigated. The relationship between drug therapy and the prevalence of H. pylori infection was also analyzed. RESULTS: H. pylori-positive rate of the 90 CD patients attending our clinic was 16.7%, significantly lower than the rate in healthy controls (40.2%) (P = 0.0001). The involvement of H. pylori infection in the gastroduodenal lesions of CD patients was also examined. The prevalence of gastroduodenal lesions in all CD patients was high, 92.2%. The lesions observed included ulcers, erosion, and "bamboo joint-like lesions" of the stomach, and ulcers, erosion, stenosis, and elevated lesions of the duodenum. None of these lesions were found to be related to H. pylori infection. However, H. pylori infection was found to exacerbate gastric ulcers (P = 0.036). The analysis of a possible relationship between a history of drug therapy and the low prevalence of H. pylori infection in CD patients showed that the prevalence of H. pylori infection was significantly lower in patients who had received antibiotics for 2 weeks or more (P = 0.002). CONCLUSIONS: The results suggest that H. pylori infection is essentially unrelated to the gastroduodenal lesions observed in CD. It seems likely, however, that H. pylori infection may exacerbate gastric ulcers and that H. pylori can be eradicated by prolonged use of antibiotics.

Adolescent↗
PubMed2001

Structuring of parameters for assessing vertebral bone strength by star volume analysis using a morphological filter.

Based on the relationship between bone strength, trabecular skeletal structure, and bone mineral density (BMD), structure parameters for assessing vertebral bone strength were studied using 18 cancellous bone blocks from the third lumbar vertebra of elderly persons. The trabecular bone pattern of each bone block was binarized into a trabecular skeletal pattern by computed radiography (CR) using a morphological filter. The binarized trabecular skeletal pattern was quantified into a trabecular skeletal pixel percentage (SKP; volume parameter of the trabecular skeletal signal component) and trabecular skeletal star volume (Vt; connection parameter of the trabecular skeletal structure) by star volume analysis. Then, the BMD and elasticity of each bone block were measured by dual X-ray absorptiometry and mechanical tests to determine the correlation between SKP and Vt. In the present study, no significant correlations were observed between BMD and elasticity. Elasticity differed greatly between some bone blocks even though BMD was essentially the same. Grid-like skeletal patterns consisting of vertical and horizontal continuous lines showed higher elasticity. SKP showed higher correlations with elasticity than BMD in subset (n = 2-7) and sumset images, although the fluctuation range was narrow. Meanwhile, Vt showed higher correlations with elasticity than SKP in subset (n = 1-6) and sumset images. Vt showed stronger correlations with elasticity than SKP. This fact indicates that strong relationships exist between the connectivity of trabecular skeletal structure and bone strength. Because the SKP-BMD and Vt-BMD correlations are weak, the influences exerted by SKP and Vt seem to be independent of the influence of BMD on the bone strength of vertebra obtained from persons with advanced age. These results indicate that SKP and Vt obtained by star volume analysis using a morphological filter are effective as structure parameters for analyzing the bone quality of lumbar vertebra.

Aged↗
PubMed2001

Biallelic inactivation of retinoic acid receptor beta2 gene by epigenetic change in breast cancer.

A growing body of evidence supports the hypotheses that retinoic acid receptor beta2 (RAR beta2) is a tumor suppressor gene. Although the loss of RAR beta2 expression has been reported in many malignant tumors, including breast cancer, the molecular mechanism is still poorly understood. We hypothesized that loss of RAR beta2 activity could result from multiple factors, including epigenetic modification and loss of heterozygosity (LOH). Using methylation-specific polymerase chain reaction and LOH analysis, we found that biallelic inactivation via epigenetic changes of both maternal and paternal alleles, or epigenetic modification of one allele combined with genetic loss of the remaining allele, could completely suppress RAR beta2 expression in breast cancer. Thus, it is possible that substantial numbers of human cancers arise through suppressor gene silencing via epigenetic mechanisms that inactivate both alleles. Because of this, chromatin-remodeling drugs may provide a novel strategy for cancer prevention and treatment.

Alleles↗
PubMed2001

Heat shock protein (HSP) 47 and collagen are upregulated during neointimal formation in the balloon-injured rat carotid artery.

Heat shock protein (HSP) 47, a collagen-specific molecular chaperone, is thought to be essential for the proper processing and secretion of procollagen molecules. We investigated the time course and localization of HSP47 and collagen expression after balloon catheter angioplasty in the rat carotid artery, based on the premise that accumulation of extracellular matrix components is a main feature of intimal hyperplasia in humans and in laboratory animals. Low levels of HSP47 expression were evident in uninjured carotid arteries. Northern blot analysis revealed that HSP47 mRNA expression was markedly stimulated 1--3 days after the induced injury and a high level was maintained for 7 days, followed by a gradual decline for up to 21 days after the injury. These changes in HSP47 expression paralleled changes in alpha 1(I) collagen expression. Immunohistochemical staining revealed colocalization of HSP47 and collagen in smooth muscle cells (SMCs) of the media and intima. In situ hybridization analysis showed that activated SMCs, which proliferated and migrated into the intima, expressed high levels of HSP47. In cultured human aortic SMCs, similar upregulation of HSP47 and alpha1(I) collagen by TGF-beta was noted. These results show that SMCs activated after balloon injury express high levels of HSP47 and collagen during cell proliferation and migration, hence an overproduction of collagen and development of intimal thickening. Thus, HSP47 plays a role in the formation and progression of neointima after angioplasty.

Animals↗
PubMed2001

Formation of PCDF, PCDD, PCB, and PCN in de novo synthesis from PAH: mechanistic aspects and correlation to fluidized bed incinerators.

The difference of polychlorinated dibenzofurans (PCDF) isomer patterns between stoker type incinerators and some fluidized bed incinerators (FBI) is a key to understand the formation mechanisms in both types of incinerators. The total yield and the isomer patterns of PCDF, polychlorinated biphenyls (PCB), polychlorinated naphthalenes (PCN), and polychlorinated benzenes (PCBz) formed via de novo synthesis from polycyclic aromatic hydrocarbons (PAH) indicate that chlorinated aromatics in the FBI are formed as a result of PAH breakdown. The detailed analysis of the isomer patterns of PCDF, PCB and PCN gives a first insight into the transformation mechanism of the PAHs and the sequence of degradation, chlorination and oxygen insertion. The major chlorination takes part at the position of the C-C cleavage during degradation of the PAHs. Further chlorination of the hydrogen position of the former PAH takes part preferably in ortho-position to this chlorination or is directed by incorporated oxygen. A perylene structure in soot is proposed as basis for the observed PCDF pattern in the FBI. Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated phenols (PxCP) were formed in lower concentrations from the de novo experiments indicating an additional formation pathway for these compounds in the FBI.

Benzofurans↗
PubMed2001

Formation characteristics of PCDD and PCDF during pyrolysis processes.

In recent years, pyrolysis processes have become technologies developed to industrial scale and discussed as alternatives to the existing waste combustion technology. However, little information is published regarding PCDD/F formation characteristics during pyrolysis processes. Two common shredder fractions--industrial light shredder (ILS) and refrigerators (REF)--both with high chlorine and copper content were pyrolysed for this pyrolysis study using a pilot plant with a capacity of 100 kg/h. At oxygen concentrations below 2% and temperatures between 430 degrees C and 470 degrees C, considerable amounts of PCDD/F were formed during the pyrolysis. More than 90% of total TEQ was found in the oil fraction (gas phase). The PCDD/PCDF ratio and the homologue pattern differed significantly from those formed during waste incineration. Considering mono- to octachlorinated congeners, up to 400 times more PCDF were formed compared to PCDD. For the investigated pyrolysis conditions, the formation of low chlorinated congeners was highly favoured. The distribution of TEQ within the individual congeners were very similar in all investigated runs. More than 80% of total TEQ stem from 2,3,7,8-substituted T4CDF and P5CDF. The isomer pattern, however, did not show significant differences compared to the common waste incineration pattern suggesting that the basic formation routes are similar.

Benzofurans↗
PubMed2001

Perturbations at the high spin heme b center in the membrane-bound nitric oxide reductase.

The effects of lowering pH from 7 to 5 on the absorption, circular dichroism (MCD) and EPR spectra were studied for Paracoccus halodenitrificans nitric oxide reductase (NOR). Intensities of the characteristic bands for the high spin heme b, that at 592 nm in the absorption spectrum and those at 591 (+) and 606 (-) in the MCD spectrum decreased considerably. Concomitant cryogenic EPR spectrum indicated a drastic increase in the signal intensity due to the high spin heme b at g approximately 6, of which less than 5% had been EPR detectable at pH 7. Cyanide (x40) bound to the high spin heme b center in the reduced NOR irrespective of pH, while a much larger amount of azide (x1000) was necessary to bind to the reduced NOR at an acidic pH, ca. 5. Based on these results the structure and function of the high spin heme b center as the active site of NOR was discussed.

Absorption↗
PubMed2001

Effect of lactate on the synaptic potential, energy metabolism, calcium homeostasis and extracellular glutamate concentration in the dentate gyrus of the hippocampus from guinea-pig.

Towards understanding the role of glycolysis on synaptic function, we examined the effect of lactate on synaptic potential, energy metabolism, Ca(2+) homeostasis and extracellular glutamate in the dentate gyrus of guinea-pig hippocampus. Postsynaptic population spikes were recorded from the granule cell layer of the dentate gyrus in guinea-pig hippocampal slices after replacing glucose with lactate in the perfusion medium. Population spikes were not maintained and spontaneously recovered around 35min after the replacement of glucose with lactate. However, ATP levels of the dentate gyrus remained unchanged while those during the glucose-free condition decreased to 73% of the initial levels at 60min. Intracellular Ca(2+) was measured with the calcium indicator dye fura-2 AM, and the population spike was recorded simultaneously. Ca(2+) levels increased concomitantly with the early decay of synaptic potentials, and recovered partially with the spontaneous recovery of synaptic potentials. The time course of decay of population spikes and the increase of Ca(2+) levels during lactate replacement were similar to those during glucose deprivation. Increase in Ca(2+) levels during lactate replacement was completely blocked by the ryanodine receptor/calcium release channel antagonist dantrolene. Glutamate was released more significantly in the medium during lactate replacement than with normal Ringer solution, and less than that during glucose deprivation. Addition of the N-methyl-D-aspartate blocker, D-(-)-2-amino-5-phosphonovaleric acid, and the L-type calcium channel blocker, nimodipine, but not dantrolene blocked spontaneous recovery of population spikes. The results indicate that lactate can maintain energy levels in hippocampal slices, but cannot maintain ion homeostasis in granule cells of the dentate gyrus. Glycolysis plays an important role in maintaining ion homeostasis, and activation of N-methyl-D-aspartate and L-type calcium channels is necessary for support of synaptic function by lactate utilization.

2-Amino-5-phosphonovalerate↗
PubMed2001

Genetic ablation of orexin neurons in mice results in narcolepsy, hypophagia, and obesity.

Orexins (hypocretins) are a pair of neuropeptides implicated in energy homeostasis and arousal. Recent reports suggest that loss of orexin-containing neurons occurs in human patients with narcolepsy. We generated transgenic mice in which orexin-containing neurons are ablated by orexinergic-specific expression of a truncated Machado-Joseph disease gene product (ataxin-3) with an expanded polyglutamine stretch. These mice showed a phenotype strikingly similar to human narcolepsy, including behavioral arrests, premature entry into rapid eye movement (REM) sleep, poorly consolidated sleep patterns, and a late-onset obesity, despite eating less than nontransgenic littermates. These results provide evidence that orexin-containing neurons play important roles in regulating vigilance states and energy homeostasis. Orexin/ataxin-3 mice provide a valuable model for studying the pathophysiology and treatment of narcolepsy.

Animals↗
PubMed2001

Identification, determination, and biological evaluation of a novel styrene trimer contained in polystyrene food containers. 2.

An unidentified styrene trimer (ST) isolated from the acetonitrile extract of polystyrene (PS) food containers was characterized as (1S*,6R*,7S*,8S*,11R*)-6,11-diphenyltricyclo[6,2,2,0(2,7)]dodeca-2,9-diene. The content and migration of this compound in PS food containers were determined by GC-MS (SIM). Furthermore, an endocrine-disrupting effect was tested using in vitro and in vivo assays of the compound. In conclusion, it seems that the compound does not present the effect.

Animals↗
PubMed2001

Metaplastic carcinoma of the breast: p53 analysis identified the same point mutation in the three histologic components.

A rare case of metaplastic carcinoma of the breast with both squamous metaplasia and cartilaginous metaplasia was reported. Histologically, the neoplasm revealed complex features, which were consisting of invasive ductal carcinoma, squamous carcinomatous component and chondrosarcomatoid component. Gradual transition of each component was recognized microscopically. p53 mutation analysis disclosed the same point mutation in three histologically different components, but not in the normal epithelium. Based on the morphologic findings, immunohistochemical findings and the p53 mutation analysis, we concluded that these three components in the tumor originated from the same duct progenitor cells.

Base Sequence↗
PubMed2001

Modulation of cell adhesion and viability of cultured murine bone marrow cells by arsenobetaine, a major organic arsenic compound in marine animals.

1. In this study, we investigated the biological effects of trimethyl (carboxymethyl) arsonium zwitterion, namely arsenobetaine (AsBe), which is a major organic arsenic compound in marine animals using murine bone marrow (BM) cells and compared them with those of an inorganic arsenical, sodium arsenite, in vitro. 2. Sodium arsenite showed strong cytotoxicity in BM cells, and its IC(50) was 6 microM. In contrast, AsBe significantly enhanced the viability of BM cells in a dose-dependent manner during a 72-h incubation; about a twofold increase in the viability of cells compared with that of control cells cultured with the medium alone was observed with a microM level of AsBe. 3. In morphological investigations, AsBe enhanced the numbers of large mature adherent cells, especially granulocytes, during a 72-h BM culture. When BM cells were cultured together with AsBe and a low dose (1 u ml(-1)) of recombinant murine granulocyte/macrophage colony-stimulating factor (rMu GM-CSF), significant additive-like increasing effects were observed on the numbers of both granulocytes and macrophages originated from BM cells. However, AsBe did not cause proliferation of BM cells at all as determined by colony-forming assay using a gelatinous medium. 4. These findings demonstrate the unique and potent biological effects in mammalian cells of AsBe, a major organic arsenic compound in various marine animals which are ingested daily as seafood in many countries.

Animals↗
PubMed2001

Sez4 gene encoding an elongation subunit of DNA polymerase zeta is required for normal embryogenesis.

BACKGROUND: Sez4 identified as a seizure-activated gene shows a similarity to the yeast REV3 that encodes a catalytic subunit of the nonessential DNA polymerase zeta which is involved in error-prone translesion synthesis. Although yeast REV3 homologues in mouse and human have recently been identified and characterized, their precise roles remain elusive. RESULTS: Here we investigated the role of mouse pol zeta by targeted inactivation of the Sez4 gene. The homozygous Sez4 mutants died around embryonic day (E) 10.5. This lethal effect was the result of developmental defects and apoptotic cell death within the embryo proper at the gastrulation stage, and it was partially rescued at E12.5 by the expression of a Sez4-transgene. In wild-type embryos, Sez4 transcripts were up-regulated within the embryo proper from E7.5, correlating well with the lethal stage of Sez4-inactivation. CONCLUSION: Our findings indicate that Sez4 is essential for epiblast lineage-specific development and suggests a requirement of mammalian DNA polymerase zeta in the survival of certain subcellular populations which are indispensable to normal embryogenesis.

Animals↗
PubMed2001

Evidence that orexin-containing neurones provide direct input to gonadotropin-releasing hormone neurones in the ovine hypothalamus.

Orexins A and B (ORX) have been added recently to the growing list of neuropeptides implicated in feeding and drinking behaviour as well as neuroendocrine function. In the present study, we have used single and dual labelling immunohistochemistry and a rabbit polyclonal anti-orexin-A antibody, which recognizes both ORX A and B, to examine ORX pathways in the sheep hypothalamus. ORX immunoreactive cells were distributed in the dorsomedial hypothalamic nucleus, lateral hypothalamic area, zona incerta and perifornical area; a few cells were also observed in the anterior hypothalamic area. In contrast to distribution in the rat brain, most of the ORX immunoreactive cells are localized to the dorsomedial hypothalamic nucleus and perifornical area; scattered cells are found in lateral hypothalamic area. ORX immunoreactive fibres were widely distributed throughout the hypothalamus and preoptic area with dense innervation of the medial preoptic area and bed nucleus of stria terminalis. Dual labelling demonstrated widespread expression of the long form of the leptin receptor within all ORX cells that were examined. Thirty percent of the gonadotropin releasing hormone (GnRH) cells that were examined had ORX immunoreactive terminals in close contact with no regional or sex differences. FluoroGold injections into the preoptic area retrogradely labelled a subpopulation of ORX cells in the lateral hypothalamic/perifornical area, showing ORX cells of this region project to the preoptic and could potentially provide input to GnRH cells. These findings suggest an integral role for ORX in the regulation of GnRH cells in the sheep and thus provide evidence of a novel mechanism whereby leptin can influence reproductive neuroendocrine function.

Afferent Pathways↗
PubMed2001

Immunotactoid glomerulopathy characterized by steroid-responsive massive subendothelial deposition.

We report a case of immunotactoid glomerulopathy with unique histologic findings in serial biopsies. A 73-year-old man complained of developing general edema. Laboratory data on admission presented moderate renal dysfunction with nephrotic syndrome. There was no evidence of systemic disease that might cause secondary glomerulopathy. Light microscopy of the renal specimen revealed lobulation of glomerular tufts and massive endothelial deposition of hyaline-like periodic acid-Schiff-positive substance with neutrophilic infiltration. The deposits were positive for immunoglobulin by immunohistochemical stains but negative for Congo red stain. Electron microscopy disclosed the deposition of microtubular structure (60 nm in diameter) predominantly in the subendothelial area and to some extent in the subepithelial and mesangial areas. Some of the tubules were extremely large (100 to 130 nm in diameter) and displayed a unique scroll structure in cross-section. The patient was treated with two sessions of plasma exchange and subsequent oral prednisolone (30 mg/d). Proteinuria and renal dysfunction improved significantly in the following 2 months. Second and third renal biopsies revealed disappearance of the deposit along with the improvement of proteinuria and renal dysfunction. Because similar microtubular structures were found in neutrophils in the glomerulus as well as in the urinary sediment, phagocytosis was suggested as a possible mechanism for removal of the deposit.

Aged↗
PubMed2001

Sequelae after limb-sparing surgery with major vascular resection for tumor of the lower extremity.

PURPOSE: Limb-sparing procedures have recently replaced amputations as the treatment for tumors invading major vessels of the lower extremity. Major arteries must be reconstructed for limb salvage. The veins are not usually reconstructed. This study was undertaken to investigate the sequelae such as chronic venous disease after venous resection for tumors. METHODS: Ten patients who underwent limb-sparing surgery for a tumor of the lower extremity or retroperitoneum that required major vascular resection were studied. The median follow-up period was 48 months. After combined resection of a major artery and vein, arterial reconstruction was performed. The veins were not reconstructed. The resected veins included the inferior vena cava (n = 2), the external iliac and common femoral veins (n = 3), the superficial femoral vein (n = 3), and the popliteal vein (n = 2). The main outcome measures were clinical classification of chronic venous disease in 10 patients and air plethysmography in seven patients. RESULTS: Clinical classification was C(0A) in 6 patients, C(3A) in 1 patient, C(3S) in 2 patients, and C(4S) in 1 patient. Venous claudication with uncontrollable edema was observed in two patients with C(3S) disease. Pain and itching with inflammatory skin changes were observed in one patient with C(4S) disease. These three patients had undergone resection of the femoral vein, including the deep femoral vein along with proximal adductor muscles. Air plethysmography revealed that the ejection fraction was significantly lower and the residual volume fraction was significantly higher in the three patients with symptoms than in symptom-free patients. CONCLUSIONS: Significant chronic venous disease was observed in the patients who underwent combined resection of the femoral vein, the deep femoral vein, and the adductor muscles for a tumor.

Adult↗
PubMed2001

Liver abscess caused by Clostridium difficile.

We report the first case of an infected cyst and liver abscess caused by Clostridium difficile. It recurred 11 months later, despite therapy with vancomycin and percutaneous drainage. Administration of metronidazole following percutaneous drainage achieved a favorable outcome.

Aged↗