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Biomedical subjects

K Yamagata

Publications and source records attributed to K Yamagata.

At least 37 records · Page 2Linked to original sources
PubMed2002

Characterization of Ca(2+) signaling pathways in human mesenchymal stem cells.

Human mesenchymal stem cells (HMSC) have the potential to differentiate into many cell types. The physiological properties of HMSCs including their Ca(2+) signaling pathways, however, are not well understood. We investigated Ca(2+) influx and release functions in HMSCs. In Ca(2+) imaging experiments, spontaneous Ca(2+) oscillations were observed in 36 of 50 HMSCs. The Ca(2+) oscillations were completely blocked by the application of 10 micro M cyclopiazonic acid (CPA) or 1 micro M thapsigargin (TG). A brief application of 1 micro M acetylcholine (ACh) induced a transient increase of [Ca(2+)](i) but the application of caffeine (10 mM) did not induce any Ca(2+) transient. When the stores were depleted with Ca(2+)-ATPase blockers (CPA or TG) or muscarinic agonists (ACh), store-operated Ca(2+) (SOC) entry was observed. Using the patch-clamp technique, store-operated Ca(2+) currents (I(SOC)) could be recorded in cells treated with ACh or CPA, but voltage-operated Ca(2+) currents (VOCCs) were not elicited in most of the cells (17/20), but in 15% of cells examined, small dihydropyridine (DHP)-sensitive Ca(2+) currents were recorded. Using RT-PCR, mRNAs were detected for inositol 1,4,5-trisphosphate receptor (InsP(3)R) type I, II, and III and DHP receptors alpha1A and alpha1H were detected, but mRNA was not detected for ryanodine receptor (RyR) or N-type Ca(2+) channels. These results suggest that in undifferentiated HMSCs, Ca(2+) release is mediated by InsP(3)Rs and Ca(2+) entry through plasma membrane is mainly mediated by the SOCs channels with a little contribution of VOCCs.

Calcium↗
PubMed2001

Coexpression of microsomal-type prostaglandin E synthase with cyclooxygenase-2 in brain endothelial cells of rats during endotoxin-induced fever.

Fever is triggered by an elevation of prostaglandin E(2) (PGE(2)) in the brain. However, the mechanism of its elevation remains unanswered. We herein cloned the rat glutathione-dependent microsomal prostaglandin E synthase (mPGES), the terminal enzyme for PGE(2) biosynthesis, and examined its induction in the rat brain after intraperitoneal injection of pyrogen lipopolysaccharide (LPS). In Northern blot analysis, mPGES mRNA was weakly expressed in the brain under the normal conditions but was markedly induced between 2 and 4 hr after the LPS injection. In situ hybridization study revealed that LPS-induced mPGES mRNA signals were mainly associated with brain blood vessels, especially vein or venular-type ones, in the whole brain area. Immunohistochemical study demonstrated that mPGES-like immunoreactivity was expressed in the perinuclear region of brain endothelial cells, which were identified as von Willebrand factor-positive cells. Furthermore, in the perinuclear region of the endothelial cells, mPGES was colocalized with cyclooxygenase-2 (COX-2), which is the enzyme essential for the production of the mPGES substrate PGH(2). Inhibition of cyclooxygenase-2 activity resulted in suppression of both PGE(2) level in the CSF and fever (Cao et al., 1997), suggesting that the two enzymes were functionally linked and that this link is essential for fever. These results demonstrate that brain endothelial cells play an essential role in the PGE(2) production during fever by expressing COX-2 and mPGES.

Animals↗
PubMed2001

Virol A, a toxic trans-polyacetylenic alcohol of Cicuta virosa, selectively inhibits the GABA-induced Cl(-) current in acutely dissociated rat hippocampal CA1 neurons.

The effects of virol A (VA), a toxic component of Cicuta virosa (water hemlock), on the GABA-induced Cl(-) current (I(GABA)) in acutely dissociated rat hippocampal CA1 neurons were investigated using whole-cell patch-clamp techniques. VA reversibly reduced I(GABA) and the muscimol (Mus)-induced current (I(Mus)) in a concentration-dependent manner. The IC(50) values for VA against I(GABA) and I(Mus) were 9.6x10(-7) and 9.8x10(-7) M, respectively. VA shifted the EC(50) value of I(GABA) from 6.5x10(-6) to 2.1x10(-5) M, whereas it had no effect on the maximum response, thereby suggesting that VA inhibited I(GABA) in a competitive manner. VA had no apparent effect on current-voltage relationships for I(GABA), thus indicating the lack of voltage-dependency. On the other hand, application of VA (10(-6) M) did not additionally reduce the I(GABA) suppressed by >10(-5) M picrotoxin. VA but not bicuculline accelerated the decay phase of I(GABA), as was seen with picrotoxin. Moreover, pre-application of 10(-5) M VA reduced I(GABA). VA did not inhibit that induced by glycine (10(-4) M). These results indicate that VA inhibits I(GABA) by acting both on the GABA agonist site and on the Cl(-) channel of the GABA(A) receptor-channel complex. VA is a structurally novel type of compound that selectively inhibits the GABA(A) receptor-Cl(-) channel complexes in mammalian central nervous system neurons.

Animals↗
PubMed2001

Diagnostic significance of tau protein in cerebrospinal fluid from patients with corticobasal degeneration or progressive supranuclear palsy.

Distinguishing corticobasal degeneration (CBD) from progressive supranuclear palsy (PSP) is clinically and pathologically difficult, and a useful biological marker to discriminative these two diseases has been a subject of clinical interest. In the present study, we assessed tau protein levels in cerebrospinal fluids by sandwich ELISA to distinguish CBD from PSP. The subjects consisted of 27 cases of CBD, 30 cases of PSP, and 36 healthy controls (CTL). The tau values in CBD were significantly higher than those in PSP (P<0.001) and those in CTL (P<0.001). The assay of CSF tau provided diagnostic sensitivity of 81.5% and specificity of 80.0% between CBD and PSP according to receiver-operating characteristic (ROC) curve analysis. When values were compared separately with respect to stage of the disease, differences in the values for moderate CBD vs. moderate PSP had the greatest significance (P<0.001 sensitivity 92.3%, specificity 100.0%), followed by cases of mild CBD and PSP (P<0.005, sensitivity 100.0%, specificity 87.5%). The values in severe CBD and PSP were not significantly different (P=0.07, sensitivity 100%, specificity 75.0%). Using data obtained from a larger number of disease cases, we confirmed our previous findings that tau protein levels in cerebrospinal fluids in patients with CBD are significantly higher than those in patients with PSP. Because tau protein levels in cerebrospinal fluids are significantly higher in early CBD cases than in early PSP cases, measurement of tau protein levels in cerberospinal fluids may be useful for the differential diagnosis of early CBD from early PSP.

Aged↗
PubMed2001

Mutations in the small heterodimer partner gene are associated with mild obesity in Japanese subjects.

Mutations in several genes encoding transcription factors of the hepatocyte nuclear factor (HNF) cascade are associated with maturity-onset diabetes of the young (MODY), a monogenic form of early-onset diabetes mellitus. The ability of the orphan nuclear receptor small heterodimer partner (SHP, NR0B2) to modulate the transcriptional activity of MODY1 protein, the nuclear receptor HNF-4alpha, suggested SHP as a candidate MODY gene. We screened 173 unrelated Japanese subjects with early-onset diabetes for mutations in this gene and found five different mutations (H53fsdel10, L98fsdel9insAC, R34X, A195S, and R213C) in 6 subjects as well as one apparent polymorphism (R216H), all present in the heterozygous state. Interestingly, all of the subjects with the mutations were mildly or moderately obese at onset of diabetes, and analysis of the lineages of these individuals indicated that the SHP mutations were associated with obesity rather than with diabetes. Therefore, an additional group of 101 unrelated nondiabetic subjects with early-onset obesity was screened for mutations in the SHP gene. Two of the previously observed mutations (R34X and A195S) and two additional mutations (R57W and G189E) were identified in 6 subjects, whereas no mutations were identified in 116 young nondiabetic lean controls (P = 0.0094). Functional studies of the mutant proteins show that the mutations result in the loss of SHP activity. These results suggest that genetic variation in the SHP gene contributes to increased body weight and reveal a pathway leading to this common metabolic disorder in Japanese.

Adolescent↗
PubMed2001

Analysis of a non-functional HNF-1alpha (TCF1) mutation in Japanese subjects with familial type 1 diabetes.

Mutations in the transcription factor hepatocyte nuclear factor-1alpha (HNF-1alpha; gene symbol TCF1) cause maturity-onset diabetes of the young type 3 (MODY3), a form of diabetes mellitus characterized by autosomal dominant inheritance, early onset, and pancreatic beta-cell dysfunction. Recent genetic studies, however, also found mutations in patients diagnosed with idiopathic (non-autoimmune based) type 1 diabetes. We identified a novel frameshift mutation (142delG) in the TCF1 gene in a family with a strong family history of type 1 diabetes and examined the functional properties of the mutant HNF 1alpha. The expression of the mutant protein was not detected in COS-7 cells by Western blot analysis after transfection of the mutant cDNA. This is the first case of an unstable mutant HNF-1alpha protein. Reporter gene analysis indicated that the mutant HNF-1alpha had no transactivation activity in HeLa and MIN6 cells. Haploinsufficiency for HNF-1alpha may lead to severe forms of diabetes like type 1 diabetes.

Adolescent↗
PubMed2001

Liver metastasis in gastric cancer with particular reference to lymphatic advancement.

BACKGROUND: We have previously reported that, in models of mesenteric lymph vessel obstruction in rats, we observed lymphaticovenous communication. This suggested that cancer cells metastasized to the liver by a lymphatic route. In the present study, we investigated the relationship between liver metastasis and lymphatic involvement in gastric carcinoma by examining resected specimens. METHODS: Twenty gastric cancer patients who had synchronous liver metastasis and 17 who developed metachronous liver metastasis after gastrectomy, performed between 1985 and 1997, were included in this study. They were compared with 44 advanced gastric cancer patients who had neither synchronous nor subsequent liver metastasis, and who survived with a disease-free course for more than 5 years. We compared the patients' clinicopathological features; in particular, we investigated extranodal invasion in the resected lymph nodes. This invasion was classified according to the pattern of extranodal cancer invasion, with or without rupture of the lymph node capsule. RESULTS: Liver metastasis was more frequent in patients with extranodal invasion than in those without extranodal invasion (P < 0.002). Multivariate analysis revealed that the correlation between extranodal invasion and liver metastasis was significant (P < 0.024); the odds ratio was 4.412. Metastasis to the lymph nodes was the next most significant risk for liver metastasis. CONCLUSION: We consider that the lymphatic system is closely related to the establishment of liver metastasis; in particular, extranodal invasion is a significant risk factor for liver metastasis in patients with gastric cancer.

Aged↗
PubMed2001

Mutation screening of the hepatocyte nuclear factor (HNF)-6 gene in Japanese subjects with diabetes mellitus.

Heterozygous mutations in the genes encoding transcription factors (HNF-1alpha, HNF-1beta and HNF-4alpha) in the hepatocyte nuclear factor (HNF) network are associated with maturity-onset diabetes of the young (MODY). We screened HNF-6 gene for mutations in 34 Japanese subjects with MODY/early-onset diabetes mellitus and 56 subjects with late-onset diabetes mellitus. One single nucleotide polymorphism (SNP) at codon 287 (GGG to GGT) was found in the gene and the frequency was similar among MODY/early-onset diabetes, late-onset diabetes and control subjects. Genetic variations in the HNF-6 gene are not likely to contribute to the susceptibility to diabetes mellitus in Japanese.

Adolescent↗
PubMed2001

Specific T-cell receptor usage with cytokinemia in Henoch-Schönlein purpura nephritis associated with Staphylococcus aureus infection.

OBJECTIVES: We sought to evaluate the mechanism of Henoch-Schönlein purpura nephritis (HSPN) associated with Staphylococcus aureus (S. aureus) infection. DESIGN: We evaluated six male patients with HSPN associated with S. aureus infection. Routine laboratory examinations, bacteriological examination, histological examination, and analysis of serum cytokine levels were performed in all cases. In addition, peripheral blood mononuclear cells (PBMC) obtained from the six patients and 45 normal individuals were stained with labelled-monoclonal antibodies against six variable parts of the beta-chain (Vbeta) of the T-cell receptor (TCR), and stained cells were analysed by flow cytometry. RESULTS: Patients with HSPN associated with S. aureus infection showed features of the nephrotic syndrome with rapidly progressive glomerulonephritis, as well as varying degrees of mesangial proliferative glomerulonephritis with crescent formation. Serological examination showed elevated levels of serum IgA and IgG as well as immune complexes after the onset of infection. The percentage of Vbeta-(5.2 + 5.3) and Vbeta 8-positive cells in patients with HSPN were significantly higher than in normal individuals; moreover, specific TCR-Vbeta usage was not observed in patients with HSPN whose S. aureus infection had improved. Serum levels of IL-1beta, IL-2, IL-6, IL-8 and TNF-alpha in patients with HSPN were significantly higher than in normal individuals, and normalized at the healing stage of S. aureus infection. CONCLUSION: Conventional antigens and/or staphylococcal enterotoxins originated from S. aureus might have been involved in the pathogenesis of HSPN in the present cohort. Therefore, steroid or other immunosuppressive therapies could not be utilized despite the high activity of glomerulonephritis, and as a result the prognoses of these cases of HSPN were serious.

Adult↗
PubMed2001

Colonic intra-epithelial carcinoma occurring in a hyperplastic polyp via a serrated adenoma.

We present a case of intra-epithelial carcinoma occurring in a serrated adenoma of the colon. The pedunculated polyp, which measured 12 x 10 x 6 mm, was endoscopically removed from the ascending colon of a 78-year-old woman. Histologically, the polyp mainly consisted of serrated adenomatous glands, and had foci of intra-epithelial carcinoma at the top. Hyperplastic (metaplastic) areas were also present in both borders between the serrated adenomatous area and the surrounding normal mucosa. A sequential increase in the degree of dysplasia, and in the number of nuclei positively reactive for Ki-67 and p53 was evident from the hyperplastic areas toward the foci of carcinoma. The polyp described here may represent a carcinogenic potential of hyperplastic polyp via serrated adenoma.

Adenocarcinoma↗
PubMed2001

A vibratory stimulation-based inhibition system for nocturnal bruxism: a clinical report.

For the single subject tested to date, the bruxism-contingent vibratory-feedback system for occlusal appliances effectively inhibited bruxism without inducing substantial sleep disturbance. Whether the reduction in bruxism would continue if the device no longer provided feedback and whether the force levels applied are optimal to induce suppression remain to be determined.

Adult↗
PubMed2001

Retroperitoneoscopic unroofing of a renal cyst under epidural anesthesia.

Laparoscopic surgery has routinely been performed under general anesthesia. Our first case of a large renal cyst treated successfully with retroperitoneoscopic unroofing under epidural anesthesia is presented here. Epidural anesthesia can be used for retroperitoneoscopic surgery if necessary.

Anesthesia, Epidural↗
PubMed2001

Th2 predominance at the single-cell level in patients with IgA nephropathy.

BACKGROUND: Abnormalities of lymphocyte function have been reported to be involved in the pathogenesis of IgA nephropathy (IgA-N). The aim of this study was to investigate helper T (Th) predominance at the single-cell level, one of the abnormalities of lymphocyte function in IgA-N. METHODS: Using flowcytometry, we assessed the levels of circulating Th cells in IgA-N patients (n=30), and in normal individuals (n=30) based on the expression of intracellular Th1 cytokines for interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), and of intracellular Th2 cytokines for IL-4, IL-10, and IL-13. Because the production of each cytokine had a specific time course, we examined cytokine synthesis at 3, 6, 9, and 12 h after stimulation. RESULTS: The percentages of IL-2-positive Th cells from IgA-N patients were significantly lower than in normal individuals at 6, 9, and 12 h, with the difference becoming greater with time. The number of IFN-gamma-positive Th cells in IgA-N patients was significantly lower than in normal individuals at 9 h, and the number of IFN-gamma-positive Th cells increased more at 12 h than at 3 h in both groups. IL-4 and IL-13 expression was increased in patients with IgA-N at 6 h compared with normal individuals. In IgA-N patients, the percentage of IL-10-positive Th cells was significantly higher than that in normal individuals at each time-point. CONCLUSION: A polarization toward Th2 response at the stimulated lymphocyte level may lead to immune abnormalities in IgA-N.

Adult↗
PubMed2001

Factors affecting renal function in 119 985 adults over three years.

Blood pressure, proteinuria and serum creatinine (SCr) were examined in 119 985 adults, aged 40 years and older, who attended annual health examinations both in 1993 and 3 years later. Renal function was assessed from SCr; changes in individuals' renal function were estimated using the slope of the regression line for the reciprocal of the SCr level vs. time (slope of rSCr) over the 3-year period. Age-dependent SCr concentration increments were observed; however, there was no significant age-dependent change in the slope of rSCr. SCr in hypertensives on anti-hypertensive medication was significantly higher than that in untreated hypertensives, borderline hypertensives and normotensives. The slopes of rSCr in hypertensives (treated, untreated and borderline) were steeper than normotensives in males, and that in untreated hypertensives was steeper than other groups in females. In hypertensives with proteinuria, SCr was higher and renal function deteriorated more rapidly, compared with hypertensives without proteinuria. Hypertension with proteinuria appears to be an important indicator for progressive decline in renal function, this trend being more obvious in males. Renal function decreases with age; however, the rate of decline is constant. The influences of proteinuria and blood pressure on renal function are different in males and females.

Adult↗
PubMed2001

Existence of variant gamma delta T cells in Crohn's disease.

BACKGROUND AND OBJECTIVES: gamma delta T cell populations are well-known for their unique distribution (e.g. intra-epithelial lymphocytes). Though their ligands play a major role in the immune response they have remained largely obscure. To shed light on this issue, we have analyzed in this study the complementarity determining region (CDR) 3 of the T cell receptor (TCR) V delta 2 chains. This provides an insight into the antigenic immune response in the intestinal mucosa in sickness and health. METHODOLOGY: Total RNA was extracted from surgically resected intestinal mucosa of patients with Crohn's disease (CD) and controls. TCR V delta 2 cDNA was PCR-amplified using V delta 2 sense primer and C delta antisense primer. The PCR products were then subcloned in pUC18 plasmid. From each sample, 20 subclones were randomly selected and subjected to nucleotide sequence analysis. RESULTS: Sequence analysis revealed that the CDR3 sequences of the TCR V delta 2 chains were unique to each individual. The evidence also showed a significant restriction of the junctional diversity of the TCR V delta 2 chains while no such restriction was found for CD. CONCLUSIONS: The marked complexity of the TCR V delta 2 junctional sequences and the oligoclonality of the TCR V delta 2 genes in the control subjects are indicative of a positive selection and expansion of specific T cells in the normal, healthy condition. In CD patients, however, the expression of distinct, non-overlapping TCR V delta 2 clonotypes can be found, suggesting polyclonal activation of gamma delta T cells in the diseased colon of CD patients. These findings have led us to conclude that accumulation of multiple gamma delta T cell clonotypes may be involved in the pathogenesis of CD.

Crohn Disease↗