Biomedical subjects

K Arai

Publications and source records attributed to K Arai.

At least 145 records · Page 8Linked to original sources

PubMed2000

In vitro analysis of STAT5 activation by granulocyte-macrophage colony-stimulating factor.

BACKGROUND: The granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor activates multiple and complex signalling pathways in response to GM-CSF stimulation. Biochemical studies suggested that signalling pathways are transmitted through protein/protein interactions, but how these biochemical cascades are initiated and transmitted in response to cytokine stimulation is largely unknown. RESULTS: To investigate these events biochemically, we established an in vitro system leading to the GM-CSF-dependent activation of Janus kinase (JAK) 2/signal transducer and activator of transcription (STAT) 5 in cell homogenates prepared from BA/F3 cells expressing the GM-CSF receptor. Activation of STAT5 DNA binding ability requires both membrane and cytoplasmic fractions while phosphorylation of JAK2 requires only the membrane fraction. Since the addition of anti-betac or phosphotyrosine antibodies inhibited GM-CSF induced STAT5 DNA binding activity, we examined the role of tyrosine residues of betac for in vitro activation of STAT5. Addition of synthetic tyrosine-phosphorylated peptides derived from betac cytoplasmic tyrosines prior to GM-CSF stimulation inhibited the in vitro activation of STAT5. The association between these tyrosine-phosphorylated peptides and STAT5 was observed by using peptide-coupling beads and BA/F3 lysates. CONCLUSIONS: We established a GM-CSF-dependent in vitro system. In cases of STAT5 activation, each phosphorylated tyrosine residue of betac can act as a docking site and enhance STAT5 activation.

Animals↗

PubMed2000

Adrenal rest tumor of the liver: a case report with immunohistochemical investigation of steroidogenesis.

A case of adrenal rest tumor arising in the liver of a 62-year-old male with chronic hepatitis type C is reported. The tumor was clinically non-functioning and required distinction from hepatocellular carcinoma. The yellowish-brown tumor measured 25 x 18 x 15 mm and was located in the subcapsular portion of the right hepatic lobe. Histologically, the tumor presented features similar to those of the adrenal cortex and was predominantly composed of pale cells. Electron micrograph revealed lipid droplets and mitochondria with tubulo-vesicular cristae, consistent with the characteristics of steroid-producing cells. Immunohistochemically, the tumor expressed the adrenal 4 binding protein and a number of enzymes involved in the synthesis of adrenocortical steroids. At surgery, the right adrenal gland was present independently from the liver. This hepatic tumor was considered to be an adrenal rest tumor with steroidogenic capability.

Adrenal Rest Tumor↗

PubMed2000

Low serum lipids suggest severe bone marrow failure in children with aplastic anemia.

BACKGROUND: Significantly low serum lipid levels are occasionally seen at the time of diagnosis in children with aplastic anemia (AA). The aim of the present study was to clarify the pathologic and clinical significance of pretreatment serum lipid levels in AA. METHODS: A questionnaire seeking precise data about AA in pediatric patients, including the initial laboratory data at the time of onset of AA and the clinical course of these patients, was sent to 18 institutes in Japan; 13 institutes responded to the questionnaire. In this retrospective study, data concerning hematologic examination and serum lipids were available for analysis in 127 children with AA. Serum lipoprotein patterns were analyzed using conventional agarose electrophoresis in eight patients. In order to elucidate the cause of hypolipidemia in AA, we assayed serum macrophage colony stimulating factor (M-CSF), which is well known to have apparent cholesterol-lowering activity, by using an enzyme-linked immunosorbent assay in seven patients with hypocholesterolemia and compared the results with those obtained in patients with iron-deficiency anemia (IDA). RESULTS: We found that pretreatment total cholesterol (TC) and triglyceride levels in the serum correlated well with counts of both nucleated cells and hemopoietic cells in the bone marrow (BM) and were inversely correlated with the lymphocyte ratio in both the BM and peripheral blood. Patients with serum TC lower than 150 mg/dL showed a poor response to any form of therapy except BM transplantation. There was no difference in the serum lipoprotein patterns between the controls and patients examined. The serum M-CSF level was significantly higher in patients with TC levels lower than 150 mg/dL compared with controls. CONCLUSIONS: These results indicate that the pretreatment serum lipid level may reflect hematopoietic activity within the BM and can help to predict the therapeutic response of each case of AA to treatment with immunosuppressive drugs, corticosteroids and anabolic steroids. These results also indicate that M-CSF may be one of the contributing causes of the hypocholesterolemia that occurs in both AA and IDA.

Adolescent↗

PubMed2000

Prognostic significance of p27Kip1 and Ki-67 expression in carcinoma of the renal pelvis and ureter.

OBJECTIVE: To determine the significance of p27(Kip1) (p27) for tumour behaviour and prognosis of patients with transitional cell carcinoma (TCC) of the renal pelvis and ureter. PATIENTS AND METHODS: Using immunohistochemical staining, the relationship was evaluated between p27 protein level (low < 50%, high > 50%) and the Ki-67 labelling index (low < 30%, high > 30%) and clinicopathological features of 37 consecutive Japanese patients with TCC of the renal pelvis and ureter. RESULTS: Low levels of p27 correlated with higher tumour stage (P < 0.05) and positive lymph node metastases (P < 0.05). There was no significant association between p27 staining and the grade and tumour proliferation as assessed by the Ki-67 index. A high Ki-67 index correlated with higher grade and stage (P < 0.05). Kaplan-Meier plots of survival rate in patients with low or high p27 staining showed that low levels correlated with a shorter disease-free and overall survival (P < 0.001 and P < 0.01, respectively). Similarly, patients with a high Ki-67 index had lower disease-free and overall survival than those with a low Ki-67 index (P < 0.01 and P < 0.05, respectively). The Cox proportional hazards model showed that a low level of p27 was an independent predictor of a shorter disease-free (P < 0.01) and overall survival (P < 0.05) on univariate analysis, but not of overall survival on multivariate analysis. A high Ki-67 index was an independent prognostic marker for shorter disease-free survival on univariate and multivariate analysis (P < 0.01) and for overall survival on multivariate analysis (P < 0.05). In those with a high Ki-67 index, increased p27 staining was associated with a better prognosis than decreased staining for disease-free and overall survival (log-rank test, P < 0. 01 and P < 0.05, respectively). CONCLUSIONS: The finding that a low level of p27 is associated with tumour invasion and unfavourable prognosis indicates that p27 may be a useful prognostic marker for survival in upper urinary tract cancer.

Aged↗

PubMed2000

Regulation of nuclear factor of activated T-cell family transcription factors during T-cell development in the thymus.

BACKGROUND: T lymphocytes undergo a series of developmental events in the thymus, and signaling through the T-cell antigen receptor is crucial in this differential program. The nuclear factor of activated T cells (NFATs) may be involved in transcriptional induction of cytokine genes and other immunoregulatory genes in T cells. OBJECTIVES: We have examined the distribution of 3 NFAT family members (NFAT1, NFATc, and NFATx) in human fetal thymocytes, by using semiquantitative RT-PCR and electrophoretic mobility shift assay. RESULTS: The messenger RNA of NFATx was expressed in all T-lymphocyte subsets tested, and expression was highest in CD4(+)CD8(+) thymocytes. Conversely, mRNA of NFAT1 was preferentially expressed in mature CD4(+) single-positive cells. NFATc mRNA was present at low levels in all subsets but was strongly induced by treatment with phorbol ester plus calcium ionophore. Using electrophoretic mobility shift assay, we observed stimulation-dependent NFAT-DNA binding in CD4(+)CD8(+) thymocytes, which was largely dependent on NFATx protein. This DNA-binding activity was inhibited by cyclosporin A, which indicated that NFATx nuclear translocation in CD4(+)CD8(+) thymocytes was regulated by calcineurin phosphatase. In contrast, NFAT1 and NFATc (and to some extent NFATx) were responsible for NFAT DNA binding in the CD4(+) cells. CONCLUSIONS: Expression of NFAT family members is differentially regulated during T-cell development, and NFATx may be involved in T-cell antigen receptor/calcineurin-dependent signaling in CD4(+)CD8(+) thymocytes.

Antibodies↗

PubMed2000

Analysis of antiapoptosis activity of human GM-CSF receptor.

Human GM-CSF (hGM-CSF) induces proliferation and sustains the viability of a mouse IL-3-dependent lymphoid cell line BA/F3 that expresses the functional hGM-CSF receptor (hGMR). To reveal an antiapoptotic mechanism of hGM-CSF, we analyzed various apoptotic markers of BA/F3 cells in various conditions. Within 24 hours of factor depletion, caspase 3-like, but not caspase 1-like, enzyme activity and DNA fragmentation were augmented. Analysis with the tyrosine kinase inhibitor (genistein) and an MEK1 inhibitor (PD98059) on antiapoptosis activity indicates that the activation of either the genistein-sensitive signaling pathway or the PD98059-sensitive signaling pathway of the betac subunit may be sufficient to suppress apoptosis through hGMR. Because hGMR mutants (which activate JAK2 but neither STAT5 nor the MAPK cascade) have antiapoptotic activity in BA/F3 cells, the involvement of JAK2, excluding the molecules mentioned earlier, for antiapoptosis activity seems likely. Because the JAK2 inhibitor AG-490 suppressed the antiapoptotic activity of hGM-CSF, the essential role for JAK2 activation to maintain the viability is considered. Interestingly, hGMR mutants, which lack MAPK cascade activation, require a higher dose of hGM-CSF than that for wild-type hGMR. Because the expression level and affinity to hGM-CSF among wild-type hGMR and mutant hGMR are the same, we speculated that biologic response is determined by a combination of strength of various signaling events.

Apoptosis↗

PubMed2000

Effect of Helicobacter pylori eradication on malignant transformation of gastric adenoma.

BACKGROUND: A nonrandomized trial of Helicobacter pylori eradication was conducted in patients with endoscopically diagnosed gastric adenoma to determine the long-term effect of antimicrobial treatment on progression of the adenoma. METHODS: Of 64 patients with an endoscopically diagnosed gastric adenoma and H pylori infection, 32 were treated with omeprazole and antibiotics to eradicate the infection, and 32 were not. RESULTS: During 2 years of follow-up, 4 (12.5%) of the 32 patients in the untreated group developed an early stage, intestinal-type gastric cancer, whereas no gastric cancer was found in the 32 patients in the treated group. CONCLUSION: H Pylori eradication may inhibit progression of gastric adenoma to carcinoma.

Adenoma↗

PubMed2000

Regulation of DNA replication during the cell cycle: roles of Cdc7 kinase and coupling of replication, recombination, and repair in response to replication fork arrest.

DNA replication is central to cell growth, development, and generation of tissues and organs. Recent advances in understanding replication machinery have revealed striking conservation of components involved in the processes of DNA replication, from yeasts to human. The conservation extends even to bacteria for some basic components of replication apparatus. Eukaryotic DNA replication is regulated at various stages to ensure strict regulation during cell cycle. We have identified a novel mammalian kinase, Cdc7-ASK (Activator of S phase Kinase), that plays a key role at the entry into S phase as a molecular switch for DNA replication. This kinase is specifically activated during S phase and triggers the firing of DNA replication by phosphorylating an essential DNA helicase component of the replication complex. Environmental stresses such as DNA damages or depletion of essential nutrients for DNA synthesis lead to unscheduled arrest of DNA replication forks. In bacteria, this leads to induction of altered modes of DNA replication, which may repair DNA damages, facilitate reassembly of replication machinery at the stalled replication fork, or do both. In eukaryotes, blocking replication forks usually induces both checkpoint responses, which prevent premature progression of cell cycle events before precise completion of the preceding cell cycle stage, and the recombinational repair system for the lesions. Possible common bases in recognition of stalled replication forks in bacteria and eukaryotes will be discussed. Furthermore, we will discuss the potential of replication and checkpoint proteins as targets of anticancer agents as well as possible novel technology for stem cell amplification through manipulation of DNA replication.

Animals↗

PubMed2000

Chromatin remodeling and T helper subset differentiation.

The T helper subsets Th1 and Th2 regulate specific types of immune responses by producing distinct sets of cytokines. Differentiation of the T helper subsets from their common precursors, naive CD4+ T cells, is induced by antigen stimulation and controlled by various other conditions. Of these conditions, the contributions of the cytokine environment have been the best characterized. The presence of interleukin-4 (IL-4) directs the differentiation towards Th2 cells, whereas IL-12 induces Thl differentiation. The Th2 signature cytokine genes encoding IL-4, IL-13, and IL-5 are clustered, and noncoding regions such as the intergenic region of the IL-4 and IL-13 genes are highly conserved from mice to humans. Alteration of the chromatin structure of this Th2 cytokine cluster region is detected as nuclease-accessible regions specific to Th2 cells. Activation of STAT6 promotes Th2 differentiation by inducing Th2-specific transcription factors, including GATA3. Expression of GATA3 induces Th2 differentiation and enhances the Th2 cell-specific chromatin accessibility, indicating that GATA3 is a key protein that regulates differentiation through chromatin remodeling. T helper subset differentiation provides a good system to study gene expression regulation at the chromatin level.

Alleles↗

PubMed2000

Humoral immunity against the proline-rich peptide epitope of the IgA1 hinge region in IgA nephropathy.

BACKGROUND: The human IgA1 hinge region is a unique mucin-like O-linked proline-rich glycopeptide, and its core peptide was found to be exposed aberrantly by the underglycosylation in IgA nephropathy (IgAN). We describe here the presence of humoral immunity against the IgA1 hinge peptide epitope in IgAN and evaluate the relationship between the underglycosylation of the IgA1 hinge region and humoral immunity. METHOD: The serum anti-IgA1 hinge peptide antibody (anti-alpha1HP ab) titre was measured and compared between the IgAN (n=37) and control groups (n=34) by enzyme-linked immunosorbent assay (ELISA) using a synthetic peptide corresponding to the human IgA1 hinge region, PVPSTPPTPSPSTPPTPSPS, as an antigen. Next, to evaluate the relationship between the underglycosylation of the IgA1 hinge region and the humoral immunity, the reactivity of the serum IgG from the patients with IgAN against monoclonal IgA1 which had been digested enzymatically to remove the carbohydrates from the IgA1 hinge region was measured by ELISA. RESULTS: The anti-alpha1HP ab titre was significantly higher in the IgAN group than in the control group (OD value: IgG class, 0.564+/-0.344 vs 0. 331+/-0.154, P=0.0014; IgM class, 0.272+/-0.148 vs 0.141+/-0.072, P<0.0001) and it was positive in approximately 40% of the patients with IgAN. In addition, the reactivity of the serum IgG from the IgAN patients against the monoclonal IgA1 was found to be increased as the carbohydrates were enzymatically removed from the IgA1 hinge region (when native=100; asialo, 122+/-9.5; agalacto, 167+/-11.5; naked, 188+/-3.9). CONCLUSION: These results suggested that the peptide epitope of the IgA1 hinge region which was aberrantly exposed by underglycosylation could induce the humoral immune response in IgAN.

Adolescent↗

PubMed2000

Aminoguanidine induces haematuria of non-glomerular origin in spontaneously hypertensive rats.

BACKGROUND: Administration of N(G)-nitro-L-arginine methyl ester (L-NAME), a non-selective inhibitor of nitric oxide synthase (NOS), induces glomerulosclerosis in spontaneously hypertensive rats (SHR). We investigated the effects of administering aminoguanidine (AG), a selective inhibitor of inducible NOS (iNOS), on glomerular histology, serum creatinine concentration, albuminuria and haematuria in SHR. METHODS: SHR and Wistar Kyoto rats (WKR) (age, 7 weeks) were given a daily water supply with or without 0.1% AG. Every 4 weeks, 24 h urine samples were collected and checked for haematuria by a dipstick method, and systolic blood pressure was measured. After 16 weeks, serum creatinine, albuminuria and glomerulosclerosis indices (GSI) were evaluated, and the size of urinary erythrocytes in AG-treated SHR was measured by flow cytometry. Glomeruli were observed by transmission and scanning electron microscopy. Some AG-treated SHR received a furosemide injection and then urinary erythrocyte size was determined. RESULTS: Systolic blood pressure, serum creatinine, albuminuria and GSI were similar between the untreated and AG-treated groups in both strains. However, AG treatment induced significant haematuria in SHR, but not in WKR. Electron microscopy did not provide any evidence for glomerular bleeding sites in AG-treated SHR. In urine with osmolalities exceeding 750 mOsm/kg, haematuria of AG-treated SHR consisted of erythrocytes smaller in size than venous erythrocytes. After furosemide injection leading to near isotonic urine, the size of urinary erythrocytes was similar to that of venous erythrocytes. CONCLUSIONS: The absence of morphological evidence for glomerular bleeding sites and similar intrinsic size between urinary and venous erythrocytes suggest that AG induces a non-glomerular type of haematuria in SHR.

Albuminuria↗

PubMed2000

Making of a facial perforator map by thermography.

It has been confirmed that thermography is an effective method by which to locate perforators to be used for local flaps. One disadvantage of thermography is its complicated procedure. If it was possible to identify perforators quickly and easily, many operations would be dramatically simplified. The authors' objective was to develop a method of mapping surface perforators using thermography. They pressed a vinyl bag filled with ice water against a test area for 25 seconds and began photographing the area directly after icing. Almost all of the enhanced hot spots appeared for 65 seconds after icing. The number and locations of enhanced perforating vessels varied widely, which they anticipated as a result of differences among individuals, and fluctuations in the measuring environment and the performance of measuring instruments. However, the presence of many perforators is common, and these images are considered to be reliable. Based on their findings, the authors consider the facial perforator map to be accurate and useful. Application of the facial perforator map may simplify many operations and may contribute to making surgery safer and more effective.

Adult↗

PubMed2000

Negative p53/positive p21 immunostaining is a predictor of favorable response to chemotherapy in patients with locally advanced bladder cancer.

The relationship between clinical response to DNA-damaging drugs and p53 and p21 status in patients with locally advanced transitional cell carcinoma (TCC) of the bladder was assessed. The response to intraarterial chemotherapy (IAC) comprising 100 mg / m(2) of cisplatin (CDDP) and 40 mg / m(2) of pirarubicin (THP) and the prognosis were assessed in 23 patients (the mean follow-up period was 19 months). The p53 gene status of tumors was analyzed at exons 5 - 8 using polymerase chain reaction-single strand conformation polymorphism analysis in 19 patients, and paraffin-embedded tumor sections were immunostained for p53 and p21 in 23 patients. The overall objective response rate (incidence of good responders) was 70%. The negative p53 group (n = 17) showed a significantly higher objective response rate than the positive p53 group (n = 6) (82% vs. 33%; P = 0.045). The p53 gene status or p21 staining status was not significantly associated with responsiveness. When the p53 and p21 immunostaining results were combined, good responders were more accurately predicted than by p53 staining status alone; the negative p53 / positive p21 group (n = 12) showed an objective response rate of 92%, which was significantly higher than that of the positive p53 and / or negative p21 group (45%, n = 11) (P = 0.027). Cause-specific survival of the negative p53 group was significantly superior to that of the positive p53 group (P = 0.015). Negative p53 / positive p21 immunostaining is a possible predictor of favorable chemotherapeutic response in patients with TCC of the bladder.

Adult↗

PubMed2000

Differential involvement of opioid receptors in stress-induced antinociception caused by repeated exposure to forced walking stress in mice.

We examined the effects of repeated exposure to forced walking stress for 6 h once a day for 0, 6 and 9 consecutive days on formalin-induced paw licking in mice. In each observation period, stress-induced antinociception (SIA) was observed only in the late phase (from 10 to 30 min), but not in the early phase (from 0 to 10 min) of formalin-induced paw licking in mice. Moreover, it was hard to develop tolerance even by daily exposure to stress for 6 days, although SIA for 9 days decreased compared with those for 0 and 6 days. Naloxone (10 mg/kg), an opioid-receptor antagonist, was effective in reducing the SIA induced by forced walking stress for 6 days and/or 9 days, but not for 0 days. Furthermore, the experiments with selective opioid-receptor antagonists, beta-funaltrexamine (mu) naltrindol (delta), or nor-binaltorphimine (kappa) demonstrated that SIA induced by forced walking stress for 9 successive days may be mediated through opioid delta- and kappa-receptors. Finally, although SIA seemed to be a unitary phenomenon, the present results strengthened the idea that SIA is induced by exposure to forced walking stress with characteristics dependent on the duration of exposure.

Animals↗

PubMed2000

QT dispersion is increased in diabetic patients with foot ulcer.

QT dispersion, a measure of inhomogenous ventricular repolarization, was measured in diabetic patients with foot ulcer. We recruited 75 patients with non insulin-dependent diabetes mellitus: patients with neuropathic ulcer (n=15, NU group), with ischemic ulcer (n=20, IU group), with previous myocardial infarction (n=20, MI group) and without any diabetic microangiopathies (n=20, DC group). We also studied normal control subjects (n=15, NC group). The interlead variability of rate corrected QT interval (QTc dispersion) was calculated. QTc interval in the MI group was significantly higher than that in the NC or DC but showed no difference in the NU and IU groups. QTc dispersion in the IU (54+/-15 msec) as well as MI (60+/-21 msec) group were significantly higher than the NC (36+/-18 msec) or DC group (39+/-14 msec). This may be due to complicated coronary artery disease in the IU group. Furthermore, QTc dispersion was also increased (49+/-14 msec) in the NU group in which cardiac autonomic nervous dysfunction was suggested. Patients with both types of diabetic ulcer demonstrated increased QT dispersion due to atherosclerosis or neurological disorder.

Aged↗

PubMed2000

[Combined effect of S-1 and CDDP as a modulator for colon 26 liver metastasis].

S-1 is a novel oral anticancer drug, composed of tegafur (FT), gimestat (CDHP) and otastat potassium (Oxo) in a molar ratio of 1:0.4:1, based on the biochemical modulation of 5-fluorouracil (5-FU). In this study the combined effect of S-1 and low-dose CDDP as a modulator for colon 26 liver metastasis in mice was evaluated. In an experiment with S-1 (5 mg/kg/day: po) and CDDP (0.25 mg/kg/day: i.p.) for 14 days, the combined effects for both liver metastasis and tumor of spleen were not superior to those with S-1 or CDDP alone group. Body weight loss was not greater in the S-1 + CDDP group than in the control group. In an experiment with S-1 (5 mg x 2/kg/day: po) and CDDP (0.25 mg/kg/day: i.p.) for 7 days, the inhibitory effects of S-1 + CDDP of liver metastasis and tumor of the spleen were remarkable compared with the S-1 alone group. However a greater loss of body weight was seen in the S-1 + CDDP group than in other groups. This study suggests that low-dose CDDP might be a modulator of S-1 for colon 26 liver metastasis. Further study is needed to determine the optimum dose and duration of treatment.

Animals↗

PubMed2000

Fatal Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis with clonal karyotype abnormality.

We report a case of Epstein-Barr virus (EBV)-associated hemophagocytic lymphohistiocytosis (HLH) with clonal karyotype abnormality. A 5-year-old boy was admitted to our hospital with persistent high-grade fever, hepatomegaly, and pancytopenia. Laboratory data disclosed a coagulation abnormality and severe liver damage. Clonal proliferation of EBV-infected cells was detected in the bone marrow by Southern hybridization, and bone marrow cells exhibited clonal chromosomal abnormality. Although the patient was treated with immunochemotherapy according to the HLH94 protocol, the disease recurred during the induction therapy, and the patient died of disseminated intravascular coagulopathy. Considering this aggressive and fatal clinical course, it is important to take intensive therapeutic measures if karyotype abnormality is noted in the treatment of EBV-HLH patients.

Bone Marrow Cells↗

PubMed2000

[The latest surgical treatment for gastric carcinoma, aiming both at cure and postoperative quality of life].

Based on the progress in both medical techniques and tools, in addition to the evaluation of accumulated cases, some new surgical treatments for gastric carcinoma have been attempted which aim both at cure and postoperative quality of life. Sentinel node navigation surgery, autonerve-preserving gastrectomy, laparoscopic surgery and extended surgery combined with neo-adjuvant chemotherapy are reviewed as the treatments promising further development. While it is true that many problems remain to be settled in each treatment, the advantages of these new treatments are greater than those of the standard one. A prudent attitude toward the indications and detailed study of the outcome, therefore, will be required for these treatments to become standard in the future.

Endoscopy↗