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Biomedical subjects

H Yamada

Publications and source records attributed to H Yamada.

At least 379 records · Page 21Linked to original sources
PubMed2000

Emergence of the precore mutant late in chronic hepatitis B infection correlates with the severity of liver injury and mutations in the core region.

OBJECTIVE: The reason that precore negative mutants (e-minus DNA) gradually become predominant in some patients during chronic hepatitis B virus infection is not clear. Theoretically, as long as both e-plus and e-minus DNA share the same epitopes in the core region, HBcAg-specific cytotoxic T lymphocytes (CTLs) cannot distinguish between the target peptides expressed by e-plus and e-minus DNA. Therefore, e-minus DNA may be accompanied by additional mutations in the core region, which may affect cytotoxic T lymphocyte recognition. To examine this possibility, the sequences of the precore and the entire core region of the hepatitis B virus genome were analyzed from paired serum samples in CH-B patients who experienced HBeAg to anti-HBe seroconversion (SC). METHODS: Patients were divided into two groups. Group A patients (n = 17) genome-converted to e-minus DNA in the precore region, which abolished HBeAg secretion within 3-4 yr after SC. Group B patients (n = 16) retained precore wild-type DNA for more than 3-4 yr after SC. To investigate the impact of the emergence of precore mutant type DNA on liver injury, alanine aminotransferase (ALT) levels were also examined. RESULTS: ALT flares were more severe among patients in group A than in group B. The average mean ALT level during the HBeAg negative phase of chronic infection was 54 +/- 38 in group A and 28 +/- 24 in group B. The average maximal ALT level during the HBeAg negative phase was 235 +/- 249 in group A and 83 +/- 106 in group B. Furthermore, all 17 patients in group A developed new core mutants during genome conversion. The average number of mutations in the core gene was 0.9 +/- 1.2 before genome conversion (e-plus DNA dominant phase) and increased to 2.8 +/- 1.3 for the 3-4 yr during genome conversion (e-minus DNA dominant phase). In contrast, only 56% (nine of 16) of patients in group B developed new core mutations after the loss of HBeAg. The average number of mutations in the core gene was 1.8 +/- 1.3 before SC (HBeAg-positive and e-plus DNA dominant phase), and decreased to 1.1 +/- 1.1 for 3-4 yr after seroconversion (anti-HBe-positive and e-plus DNA dominant phase). CONCLUSIONS: These data indicate that the emergence of a predominant precore negative genotype late in chronic hepatitis B virus infection is associated with the selection of additional mutations in the core gene, as well as with liver injury.

Adolescent↗
PubMed2000

Phosphorylation of nucleosides by the mutated acid phosphatase from Morganella morganii.

A novel nucleoside phosphorylation process using the food additive pyrophosphate as the phosphate source was investigated. The Morganella morganii gene encoding a selective nucleoside pyrophosphate phosphotransferase was cloned. It was identical to the M. morganii PhoC acid phosphatase gene. Sequential in vitro random mutagenesis was performed on the gene by error-prone PCR to construct a mutant library. The mutant library was introduced into Escherichia coli, and the transformants were screened for the production of 5'-IMP. One mutated acid phosphatase with an increased phosphotransferase reaction yield was obtained. With E. coli overproducing the mutated acid phosphatase, 101 g of 5'-IMP per liter (192 mM) was synthesized from inosine in an 88% molar yield. This improvement was achieved with two mutations, Gly to Asp at position 92 and Ile to Thr at position 171. A decreased K(m) value for inosine was responsible for the increased productivity.

Acid Phosphatase↗
PubMed2000

Procollagen IIC-peptide as a marker for assessing mechanical risk factors of knee osteoarthritis: effect of obesity and varus alignment.

OBJECTIVE: To ascertain by cross sectional examination whether the concentration of procollagen IIC-peptide in joint fluid significantly correlates with mechanical risk factors of knee osteoarthritis (OA), such as obesity (body mass index) and varus alignment (lateral femorotibial angle). METHODS: The concentrations of procollagen IIC-propeptide in synovial fluid were measured by a sandwich enzyme immunoassay of 65 patients with the same radiological stage of primary knee OA-that is, Ahlbäk stage I. The relations between procollagen IIC-peptide and body mass index and lateral femorotibial angle were examined using simple regression analysis and multiple regression analysis. RESULTS: Significant positive correlations were found between procollagen IIC-propeptide concentrations and body mass index (r=0.479, p<0.0001), and between procollagen IIC-propeptide concentrations and lateral femorotibial angle (r=0.375, p=0.0021). Significant correlations were also found by multiple regression analysis. The multiple correlation coefficient of body mass index and femorotibial lateral angle to the procollagen IIC-propeptide concentrations was 0.547 (p<0.0001). CONCLUSIONS: The findings suggest that synthesis of type II collagen by chondrocytes is enhanced by abnormal mechanical stress, in this case obesity and varus alignment. It is concluded that procollagen IIC-propeptide concentrations in joint fluid are a useful marker of early OA.

Biomarkers↗
PubMed2000

Matrix metalloproteinases and tissue inhibitors of metalloproteinases in synovial fluids from patients with rheumatoid arthritis or osteoarthritis.

OBJECTIVE: Matrix metalloproteinases (MMPs) are expressed in joint tissues of patients with rheumatoid arthritis (RA) and osteoarthritis (OA). The objective of this study was to define the steady state levels of seven different MMPs and two tissue inhibitors of metalloproteinases (TIMPs) as well as the potential metalloproteinase activity in the synovial fluid (SF) to provide more insight into the role of MMPs in cartilage destruction in RA and OA. METHODS: Levels of MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-13, TIMP-1, and TIMP-2 in SF aspirated from knee joints of 97 patients with RA and 103 patients with OA were measured by the corresponding one step sandwich enzyme immunoassays. Proteolytic activity of MMPs in these SFs was examined in an assay using [(3)H]carboxymethylated transferrin substrate in the presence of inhibitors of serine and cysteine proteinases after activation with p-aminophenylmercuric acetate (APMA). Destruction of RA knee joints was radiographically evaluated. RESULTS: Levels of MMP-1, MMP-2, MMP-3, MMP-8, and MMP-9 were significantly higher in RA SF than in OA SF. MMP-7 and MMP-13 were detectable in more than 45% of RA SFs and in less than 20% of OA SFs, respectively. Among the MMPs examined, MMP-3 levels were extremely high compared with those of other MMPs. Direct correlations were seen between the levels of MMP-1 and MMP-3 and between those of MMP-8 and MMP-9 in RA SF. Although the levels of MMP-1 and MMP-3 increased even in the early stage of RA, those of MMP-8 and MMP-9 were low in the early stage and increased with the progression of RA. Molar ratios of the total amounts of the MMPs to those of the TIMPs were 5.2-fold higher in patients with RA than in OA, which was significant. APMA-activated metalloproteinase activity in SF showed a similar result, and a direct correlation was seen between the molar ratios and the activity in RA SF. CONCLUSIONS: Our results show that high levels of MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, and TIMP-1 are present in RA SF and suggest that once these MMPs are fully activated, they have an imbalance against TIMPs, which may contribute to the cartilage destruction in RA.

Adult↗
PubMed2000

Vascular permeability: quantitative measurement with double-echo dynamic MR imaging--theory and clinical application.

Double-echo dynamic magnetic resonance (MR) imaging was used to evaluate both vascularity and permeability of tissues simultaneously. Vascularity was evaluated on the basis of the T2*-shortening effect due to the intravascular fraction of the contrast agent and permeability on the basis of the T1-shortening effect due to the extravascular fraction. Meningioma was characterized on the basis of higher vascularity and neurinoma on the basis of higher permeability. The proposed method enables better tissue characterization.

Adult↗
PubMed2000

Factor XII deficiency in women with recurrent miscarriage.

Congenital thrombophilia is known to cause significant maternal complications, and possibly has an adverse effect on normal fetal development. The aim of this study was to assess the prevalence of factor XII (FXII) deficiency in women with a history of recurrent miscarriage. Two hundred and forty-one consecutive Japanese women with a history of two or more recurrent miscarriages were prospectively assessed for their etiology by conventional screening methods. Seven women were found to have reduced FXII activity (19. 2-46.1%) and prolonged activated partial thromboplastin time (33. 3-51.3 s). Of these 7 women, 6 had experienced early pregnancy losses, while 1 woman had experienced repeated mid-trimester fetal losses with coincidental gestational thrombocytopenia. In 241 women with a history of recurrent miscarriage, the prevalence of FXII deficiency was 2.9%.

Abortion, Spontaneous↗
PubMed2000

Effects of inflammatory cytokines on prostaglandin E(2) production from human amnion cells cultured in serum-free condition.

The effects of five inflammatory cytokines, i.e. interleukin(IL)-1alpha, IL-1beta, IL-6, IL-8 and tumor necrosis factor-alpha (TNF-alpha) on prostaglandin E(2) (PGE(2)) production from amnion cells cultured in a serum-free condition was evaluated. After human amnion cells obtained from term placenta were incubated with the inflammatory cytokines at various concentrations, PGE(2) production in the culture supernatant was determined using an enzyme immunoassay method. Under a serum-free culture condition, an increase in PGE(2) production by IL-1alpha and IL-1beta was observed at concentrations of 10 and 100 ng/ml compared to control cultures. However, the increases in PGE(2) production by IL-6 and IL-8 were found at relatively high concentrations, i.e. at 100 and 200 ng/ml. TNF-alpha induced a significant increase in PGE(2) production at 50 and 100 ng/ml, but not at 200 ng/ml. These data suggest that these inflammatory cytokines directly stimulate PGE(2) production from amnion cells and may initiate premature labor if amniotic inflammatory cytokines are elevated, e.g. following intrauterine infection.

Adult↗
PubMed2000

Reversal of intra-amniotic Chlamydia trachomatis antigen status.

Chlamydia trachomatis (CT) infection in pregnant women is related to unfavorable obstetric outcomes such as prematurity, intrauterine growth retardation, and stillbirth. A 22-year-old woman underwent transabdominal amniocentesis at 16 weeks of gestation (GW). A CT antigen test using polymerase chain reaction in the amniotic fluid was found to be positive, though the patient had no symptom of infection. Beginning at 20 GW, clarithromycin was orally administered at a dose of 400 mg/day for 2 weeks. The CT antigen test in amniotic fluid at 28 GW turned to a negative result. A female baby was vaginally born at 38 GW by spontaneous labor. The CT antigen test of her gastric contents showed a negative result and anti-CT IgM in umbilical cord blood was negative. Neither respiratory distress, pneumonia, nor conjunctivitis was detected. To the best of our knowledge, this case is the first report showing the reversal of the intra-amniotic CT antigen status by antibiotic treatment.

Adult↗
PubMed2000

Protective role of extracellular superoxide dismutase in hemodialysis patients.

BACKGROUND: The superoxide anion and other oxygen radicals have been implicated in the progression of chronic renal failure, and are removed by extracellular superoxide dismutase (EC-SOD) in the extracellular space on the surface of the endothelium. A single-base substitution of the EC-SOD gene which reduces the binding capability to endothelial cells resulting in an increased serum concentration, has been identified in healthy persons and hemodialysis patients. RESULTS: The proportion of patients with this mutation among hemodialysis patients in each 20 months' duration after the initiation of hemodialysis was retrospectively studied. The percentage of substitution-positive patients declined 80 months after the start of hemodialysis in non-DM patients. In contrast, in DM patients, the rapid decrease was obvious as early as 40 months after the initiation of hemodialysis. By prospective study for 5 years, there were significant differences in the survival rate between patients with and without R213G in DM, but not in non-DM patients. Among those who died, the incidence of ischemic heart disease and cerebrovascular disease in cases with R213G was significantly higher than in cases without R213G. CONCLUSION: These results suggest that the presence of a substitution in the EC-SOD gene at the heparin-binding domain could be a prognostic marker of dialysis patients.

Cause of Death↗
PubMed2000

A rapid and simple photometric assay for quantification of eosinophil chemotaxis.

Various methods have been devised to assay eosinophil chemotaxis. In this review, we introduced a rapid and sensitive eosinophil chemotactic assay system based on eosinophil peroxidase (EPO) determination. Eosinophils were semipurified by dextran sedimentation followed by Percoll gradient centrifugation. Eosinophil migration was measured by the Boyden blind-well chamber technique using a 96-well multiwell chamber and polycarbonate membrane filter. The number of migrated eosinophils was assessed by determination of the EPO activity of drop-off cells, and photometric measurement was performed with a microtiter plate reader. The contribution of neutrophil peroxidase to the assay is negligible, and the assay is sensitive enough to detect 200 eosinophils. The method is both less tedious and less laborious than conventional manual methods, and it allows a large number of samples to be analyzed within 4 h. When eosinophils were exposed to 15 chemokines and their migration was assayed using this method, we found that only CC chemokine receptor 3 ligands, such as eotaxin, induced significant eosinophil migration.

Chemotaxis, Leukocyte↗
PubMed2000

Acid instillation enhances the inflammatory response to subsequent lipopolysaccharide challenge in rats.

Aspiration of gastric contents is one of leading causes of the acute respiratory distress syndrome (ARDS). The pathogenesis of acid aspiration-induced acute lung injury is well understood. Less clear is why patients who have suffered acid aspiration are susceptible to ARDS. We studied the effects of acid instillation on the inflammatory response to subsequent lipopolysaccharide (LPS) challenge in rats. Instillation of acid into the right lung worsened the pathology induced by LPS that was administered 24 h after acid instillation. This included worsened oxygenation, increased pulmonary edema, increased production of tumor necrosis factor-alpha (TNF-alpha) and cytokine-induced neutrophil chemoattractant, neutrophil accumulation and mobilization to the alveolar spaces, and nitric oxide (NO) production. Of interest, neutrophil mobilization, NO production, and protein permeability were also magnified in the left lung. These effects were attenuated by administration of the protein tyrosine kinase (PTK) inhibitors genistein and tyrphostin AG556. These data suggest that acid instillation primes the rat to enhance the inflammatory response to subsequent endotoxin challenge and that at least part of the augmented inflammatory response depends on PTK.

Animals↗
PubMed2000

High glucose suppresses cathepsin activity in periodontal-ligament-derived fibroblastic cells.

The accumulation of extracellular matrices and integrins by high glucose has been reported in relation to diabetic complications. We previously reported that PDL cells expressed a higher amount of VLA-5 when cultured in high-glucose (4500 mg/L) medium than those cultured in low-glucose (1100 mg/L) medium. In this study, we aimed to address (1) whether this effect was mediated by the transcriptional level of the gene or the degradative level of the protein, and (2) whether this effect was mediated by TGF-beta. The results indicated that the level of mRNA encoding alpha5 integrin did not change in PDL cells regardless of the concentration of glucose. Alternatively, high glucose suppressed cathepsin B+L activity. Additionally, the level of mRNA encoding TGF-beta was not affected by high glucose, nor did an anti-TGF-beta neutralizing antibody have an effect on the expression of beta5 gene or cathepsin activity. Therefore, the effects of high glucose appeared to be mediated by impaired protein degradation, but not by autocrine TGF-beta.

Autocrine Communication↗
PubMed2000

Cocaine-amphetamine-regulated transcript (CART) acts in the central nervous system to inhibit gastric acid secretion via brain corticotropin-releasing factor system.

Recent study has indicated that cocaine-amphetamine-regulated transcript (CART) is an anorectic chemical in the brain. In the present study, we examined the hypothesis that CART may act in the central nervous system to alter gastric function. Food consumption, gastric acid secretion, and gastric emptying were measured after injection of CART into the cerebrospinal fluid in 24-h fasted Sprague Dawley rats. Central injection of CART inhibited food intake, gastric acid secretion, and gastric emptying. In contrast, ip injection of CART failed to inhibit gastric acid secretion and gastric emptying, suggesting that CART acts in the brain to suppress gastric acid secretion and gastric emptying. In the vagotomized animals, centrally administered CART did inhibit pentagastrin-stimulated gastric acid secretion. The CART-induced acid inhibition was also observed in rats treated with indomethacin, a cyclooxygenase inhibitor. In contrast, pretreatment with central administration of a CRF receptor antagonist, alpha-helical CRF9-41, completely blocked the central CART-induced inhibition of gastric acid secretion. All these results suggest that CART acts in the brain to inhibit gastric function via brain CRF system. The vagal pathway and the prostaglandin system are not involved in the acid inhibition.

Animals↗
PubMed2000

Synaptic-like microvesicles, synaptic vesicle counterparts in endocrine cells, are involved in a novel regulatory mechanism for the synthesis and secretion of hormones.

Microvesicles in endocrine cells are the morphological and functional equivalent of neuronal synaptic vesicles. Microvesicles accumulate various neurotransmitters through a transmitter-specific vesicular transporter energized by vacuolar H(+)-ATPase. We found that mammalian pinealocytes, endocrine cells that synthesize and secrete melatonin, accumulate l-glutamate in their microvesicles and secrete it through exocytosis. Pinealocytes use l-glutamate as either a paracrine- or autocrine-like chemical transmitter in a receptor-mediated manner, resulting in inhibition of melatonin synthesis. In this article, we briefly describe the overall features of the microvesicle-mediated signal-transduction mechanism in the pineal gland and discuss the important role of acidic organelles in a novel regulatory mechanism for hormonal synthesis and secretion.

Glutamic Acid↗
PubMed2000

Direct identification of a novel disulfide bond linkage system of new isolated isomer (isomer V) in recombinantly produced h-IGF-I.

Insulin-like growth factor I (IGF-I or somatomedin C) is a serum polypeptide with three intramolecular disulfide bonds. In the course of synthesis by the recombinant DNA method, three disulfide bond isomers, all of which have Cys18-Cys61 with three combinations of two disulfide bonds formed by Cys6, Cys47, Cys48 and Cys52, were identified. Natural type, isomer II, was proved to have a Cys6-Cys48, Cys18-Cys61, Cys47-Cys52 disulfide bond system. Now, the fourth isomer, isomer V which doesn't have Cys18-Cys61 disulfide, has been isolated, and its novel disulfide bond linkage system was identified by a chemical synthetic method. The supposed conformation constrained in 3D structure for isomer V would be discussed for its biological activity.

3T3 Cells↗
PubMed2000

Left cervical aortic arch with aortic coarctation and saccular aneurysm.

Cervical aortic arch is a very rare malformation and is occasionally accompanied by other cardiovascular anomalies. A 48-year-old male patient had a left cervical aortic arch with aortic coarctation and saccular aneurysm distal to the coarcted segment. The major clinical manifestations were upper body hypertension with a 50-mmHg discrepancy between the upper and lower limbs and a loud continuous murmur in the upper chest and back. Magnetic resonance angiography successfully depicted the anomalous aorta, and the aortic coarctation and aneurysm were surgically resected and the thoracic aorta was reconstructed. The discrepancy in blood pressure diminished after the operation, but antihypertensive medication was continued to satisfactorily control the hypertension.

Aorta, Thoracic↗
PubMed2000

Identification and characterization of a novel gene, hos3+, the function of which is necessary for growth under high osmotic stress in fission yeast.

hos3 mutants of the fission yeast Schizosaccharomyces pombe showed the phenotype of high osmolarity sensitivity for growth. An S. pombe strain carrying the hos3-M26 allele cannot form colonies on agar plates containing 2 M glucose, but the parental strain can do so very well, as demonstrated previously. The hos3+ gene was cloned and identified as one that encodes a small protein of 94 amino acids, which shows no sequence similarity to any other proteins in the current databases. A hos3delta strain, which we then constructed, had the phenotype of high osmolarity sensitivity, as in the case of the original hos3-M26 mutant. More interestingly, when these hos- cells were grown in the non-permissive growth condition in the presence of 2 M glucose, we found that unusually many septated cells were accumulated after a prolonged incubation. A multicopy suppressor gene for hos- mutations was also isolated and identified as the dsk1+ gene encoding a protein kinase, which was previously suggested to be implicated in a process of the mitotic regulation of S. pombe. The function of the hos3+ gene is discussed from these results.

Cloning, Molecular↗