Search PubMed⌕ Search

Biomedical subjects

S Saitoh

Publications and source records attributed to S Saitoh.

At least 73 records · Page 4Linked to original sources
PubMed2000

Compressive force promotes chondrogenic differentiation and hypertrophy in midpalatal suture cartilage in growing rats.

Midpalatal suture cartilage (MSC) is secondary cartilage located between the bilateral maxillary bones and has been utilized in the analysis of the biomechanical characteristics of secondary cartilage. The present study was designed to investigate the effects of compressive force on the differentiation of cartilage in midpalatal suture cartilage in rats. Forces of various magnitudes were applied to the midpalatal suture cartilage in 4-week-old male Wistar rats for 1, 2, 4, 7, or 14 days, mediated through the bilateral 1st molars using orthodontic wires. The differentiation pathways in the MSC cells were examined by immunohistochemistry for the differentiation markers type I, type II and type X collagen, and glycosaminoglycans (GAGs), chondroitin-4-sulfate, chondroitin-6-sulfate and keratan sulfate. Histologically and immunohistochemically, the midpalatal suture cartilage in control rats had the characteristic appearance of secondary cartilage. In the experimental groups, the center of the midpalatal suture cartilage that contained osteo-chondro progenitor cells seemed to become mature cartilage and its immuno-reaction to type II and X collagen and GAGs increased as the experiment progressed. This differentiation was dependent upon the magnitude and duration of the force applied to the midpalatal suture cartilage; i.e., cartilaginous differentiation progressed more rapidly as the applied force increased. The present results suggest that the differentiation of osteo-chondro progenitor cells into mature and hypertrophic chondrocytes in the precartilaginous cell layer is promoted by compressive force.

Animals↗
PubMed2000

Application of the chromatin immunoprecipitation method to identify in vivo protein-DNA associations in fission yeast.

The chromatin immunoprecipitation (ChIP) method provides an ideal tool for detecting direct or indirect interactions between proteins of interest and DNAs with known sequences. Here, we introduce the ChIP protocol used in our laboratory to identify in vivo protein-DNA association in the fission yeast Schizosaccharomyces pombe. The cytological and genetic merits of the fission yeast for studying control of the eukaryotic cell cycle and chromosome dynamics are reinforced by application of this ChIP method.

Antibodies↗
PubMed2000

Molecular genetic study of japanese patients with X-linked alpha-thalassemia/mental retardation syndrome (ATR-X).

X-linked alpha-thalassemia/mental retardation syndrome (ATR-X) is one of the many known X-linked mental retardation syndromes. Mutations in the ATR-X gene (ATRX) that encodes a putative global transcription factor have been identified in patients with ATR-X as well as those with other forms of X-linked mental retardation syndrome. To better understand the genetic basis of ATR-X, we investigated nine patients with the ATR-X phenotype from eight independent Japanese families for mutations in ATRX. We identified seven missense mutations, including six novel mutations, all of which were located either in the N-terminal region corresponding to the putative zinc finger domain (N179S, P190L, V194I, and R246C) or in the C-terminal region corresponding to the helicase domain (V1552F, L1645S, and Y1847C). R246C was found in two independent patients. Furthermore, we investigated the origin of the mutations in seven mothers. Five mothers were found to be carriers, and two were not, indicating de novo origin of the mutations. When we compared clinical manifestations with respective mutations, we could not find apparent phenotype-genotype correlation. Therefore, the putative zinc finger domain and the helicase domains may have similar functional significance for the function of ATRX.

Adult↗
PubMed2000

Serine 6 of Lck tyrosine kinase: a critical site for Lck myristoylation, membrane localization, and function in T lymphocytes.

Lck is a member of the Src family kinases expressed predominantly in T cells, and plays a pivotal role in TCR-mediated signal transduction. Myristoylation of glysine 2 in the N-terminal Src homology 4 (SH4) domain of Lck is essential for membrane localization and function. In this study, we examined a site within the SH4 domain of Lck regulating myristoylation, membrane localization, and function of Lck. A Lck mutant in which serine 6 (Ser6) was substituted by an alanine was almost completely cytosolic in COS-7 cells, and this change of localization was associated with a drastic inhibition of myristoylation in this mutant. To assess the role of Ser6 of Lck in T cell function, we established stable transfectants expressing various Lck mutants using Lck-negative JCaM1 cells. The Lck mutant of Ser6 to alanine, most of which did not target to the plasma membrane, was not able to reconstitute TCR-mediated signaling events in JCaM1 cells, as analyzed by tyrosine phosphorylation of intracellular proteins and CD69 expression. These results demonstrate that Ser6 is a critical factor for Lck myristoylation, membrane localization, and function in T cells, presumably because the residue is important for N-myristoyl transferase recognition.

Alanine↗
PubMed2000

Incidence of primary cholangiocellular carcinoma of the liver in japanese patients with hepatitis C virus-related cirrhosis.

BACKGROUND: Hepatitis C virus (HCV) infection is a major risk factor for the development of hepatocellular carcinoma. However, the risk factors for primary cholangiocellular carcinoma of the liver (PCC-L) have not been fully investigated. The authors determined the incidence of PCC-L in patients with HCV-related cirrhosis. METHODS: Between 1980 and 1997, the authors prospectively studied 600 consecutive patients for the appearance of PCC-L; these patients were positive for HCV and later developed cirrhosis. The follow-up period ranged from 0 to 18.5 years (median, 7.2 years). RESULTS: During the observation period, PCC-L developed in 14 patients (2.3%). Among these, 11 (1.8%) had cholangiocellular carcinomas and the other 3 (0.5%) had a combined type of hepatocellular and cholangiocellular carcinoma. Within the same period, hepatocellular carcinoma (HCC) developed in 206 patients (34.3%). The cumulative rates of newly diagnosed PCC-L were 1.6% at 5 years and 3.5% at 10 years, which was about 1000 times higher than the estimated incidence of PCC-L in the general population of Japan. PCC-L was treated by surgical resection in 3 patients who survived for > 3 years. However, the other 11 patients received palliative therapy or chemotherapy. The survival rates among PCC-L patients were 39.3%, 23. 6%, and 16.5% at the end of 1, 3, and 5 years, respectively, and were significantly lower than those of HCC (P = 0.0001). CONCLUSIONS: The results of this study show a relatively high incidence of PCC-L in patients with HCV-related cirrhosis, and also show that this type of liver cancer is associated with a relatively poor prognosis. These results indicate that HCV-related cirrhosis is a major risk factor for PCC-L in Japanese patients.

Adult↗
PubMed2000

Parent-of-origin specific histone acetylation and reactivation of a key imprinted gene locus in Prader-Willi syndrome.

To examine the chromatin basis of imprinting in chromosome 15q11-q13, we have investigated the status of histone acetylation of the SNURF-SNRPN locus, which is a key imprinted gene locus in Prader-Willi syndrome (PWS). Chromatin immunoprecipitation (ChIP) studies revealed that the unmethylated CpG island of the active, paternally derived allele of SNURF-SNRPN was associated with acetylated histones, whereas the methylated maternally derived, inactive allele was specifically hypoacetylated. The body of the SNURF-SNRPN gene was associated with acetylated histones on both alleles. Furthermore, treatment of PWS cells with the DNA methyltransferase inhibitor 5-azadeoxycytidine (5-aza-dC) induced demethylation of the SNURF-SNRPN CpG island and restoration of gene expression on the maternal allele. The reactivation was associated with increased H4 acetylation but not with H3 acetylation at the SNURF-SNRPN CpG island. These findings indicate that (1) a significant role for histone deacetylation in gene silencing is associated with imprinting in 15q11-q13 and (2) silenced genes in PWS can be reactivated by drug treatment.

Acetylation↗
PubMed2000

Multiple telescoping anastomosis on an artery.

The telescoping anastomotic technique was carried out four times on the rat femoral artery in order to examine whether the technique could safely be used three to four times for repair of an artery that was injured at two different sites. In addition, the technique was repeated five and six times to determine the maximum number of anastomosis that could be performed on an artery and to clarify problems of the telescoping anastomosis. In the rats in which the anastomosis was carried out four and five times, 100% patency was obtained, while the first occlusion occurred in a graft on which the anastomosis was repeated six times. The telescoping technique appeared to safely be used three or four times for repair of an artery that had been divided at two sites if tension of the repaired vessel was kept low by the grafting, and torsion of the graft and deformities of the inserted vessel were minimal.

Animals↗
PubMed2000

Ectopic calcification following tibial fracture: property analysis.

We present a patient whose ectopic calcification following deep posterior compartment syndrome was studied by electron microscopy, chemical analyses, and X-ray diffraction. The patient complained of a toe flexion deformity following a tibial fracture which he sustained 18 years earlier. Damage to the peroneal artery was demonstrated by magnetic resonance angiography, suggesting that the patient had had deep posterior compartment syndrome in the past. A large radiopaque mass, identified in the flexor hallucis longus muscle by radiographs and computed tomography, was resected, resulting in a dramatic improvement of the toe deformity. The resected material was analyzed in detail. It included no osseous tissue, and was not birefringent under a polarizing microscope, being compatible with ectopic calcification rather than ossification. On electron microscopy the material was found to be an assembly of tiny rods. Chemical and X-ray diffraction analyses suggested a carbonate-containing apatite as the most probable substance.

Adult↗
PubMed2000

Total energy expenditure of elite synchronized swimmers measured by the doubly labeled water method.

To determine the daily energy requirement of elite synchronized swimmers during moderate-intensity training, the average daily energy expenditure measured by the doubly labeled water method, was calculated for nine female Japanese national team synchronized swimmers [four senior; mean (SD) 22.5 (1.0) years old, 52.2 (3.6) kg, and five junior; 17.6 (1.1) years old, 52.8 (2.3) kg]. Their total energy expenditure (TEE) was 11.5 (2.8) MJ x day(-1) [2738 (672) kcal day(-1)]. When compared with estimated energy requirements derived from "Recommended Dietary Allowances for the Japanese", 12.1 (0.6) MJ day(-1) [2897 (139) kcal day(-1)], there was no difference between mean actual and estimated energy requirements. However, there were considerable differences observed on an individual basis. Their energy intake, estimated from 7- day self-reported dietary records, was 8.9 (1.7) MJ day(-1) [2128 (395) kcal x day(-1)], which was significantly lower than their TEE (P<0.05). Resting energy expenditure (REE), as determined by indirect calorimetry, was 5.2 (0.3) MJ x day(-1) [1247 (75) kcal x day(-1)]. Their physical activity level (TEE/REE) was 2.18 (0.43). These results demonstrate that the TEE values of elite female synchronized swimmers are not dissimilar to those reported for athletes participating in other sports, especially competitive swimmers during moderate-intensity training.

Adolescent↗
PubMed2000

A comparison of resistance and aerobic training for mass, strength and turnover of bone in growing rats.

To determine the effects of resistance versus aerobic exercise on the mass, strength and turnover of bone. thirty Sprague Dawley rats (4 weeks of age) were assigned to one of three experimental groups: sedentary, running or jumping. In the jumping group, the trunk was kept upright during electrically stimulated jumping exercise for 1 h every other day. The running rats ran at speeds of 24 m/min for 1 h every other day. After 4 weeks, the jumping rats exhibited increases in the mass and strength of the lumbar vertebrae and of the mid-diaphysis of the femur (mid-femur), and increases in the cross-sectional morphology of these bones: the trabecular bone volume per bone surface, the trabecular thickness, the trabecular bone formation rate per bone surface (BFR/BS). In addition, they exhibited reduced trabecular separation and the area of osteoclast surface per bone surface. The running and sedentary rats showed no such changes. With regard to the mid-femur, in both the jumping and running rats the periosteal BFR/BS was increased. However, only the jumping rats showed a reduction in the BFR/BS at the endocortical surface. These results suggest that resistance exercise accelerates cortical drift and increases the bone mass and strength by stimulating bone formation more efficiently than does aerobic exercise.

Animals↗
PubMed2000

Fluctuation patterns of HCV-RNA serum level in patients with chronic hepatitis C.

The serum level of hepatitis C virus (HCV)-RNA is clinically important as a predictor of the response to interferon (IFN) therapy in patients with chronic hepatitis C. If serum HCV-RNA levels fluctuate during follow-up, and IFN therapy is begun at the time of a low HCV-RNA level, the IFN therapy may be more effective. We evaluated the fluctuation of HCV-RNA serum levels for 2 years in 212 patients with chronic hepatitis C, untreated with IFN who had HCV genotype 1b and an HCV-RNA level of 10 Meq/ml or more at first consultation. The HCV-RNA level was measured monthly for 2 years with an HCV branched DNA probe assay (b DNA probe assay). We classified HCV-RNA patterns into three types by the ratio of maximum HCV-RNA level (a) to minimum HCV-RNA level (b). In pattern 1 (constant type, 151 patients; 71.2%) the a/ b ratio was 1-5. In pattern 2 (slight fluctuation type, 46 patients; 21.7%) the a/b ratio was 5-10. In pattern 3 (severe fluctuation type, 15 patients; 7.1%), the a/b ratio was 10 or more. Next, we evaluated the factors associated with the three patterns. Acute exacerbation of chronic hepatitis was regarded as an increase in serum alanine aminotransferase (ALT) level to more than 250 IU/l. The incidence of acute exacerbation for a 2-year follow-up was 13.9% (21/151) in pattern 1, 19.6% (9/46) in pattern 2, and 53.3% (8/15) in pattern 3. Multivariate analysis showed that acute exacerbation was the most important factor in the manifestation pattern 3. In conclusion, we found that: (1) about 70% of patients had a constant HCV-RNA levels for 2 years. (2) A few patients had severe fluctuation of serum HCV-RNA level after acute exacerbation of chronic hepatitis.

Adult↗
PubMed2000

Hepatic vascular side effects of styrene maleic acid neocarzinostatin in the treatment of hepatocellular carcinoma.

Styrene-maleic acid neocarzinostatin (SMANCS) sometimes causes hepatic vascular side effects, including arterial stricture, obstruction, and arterio-portal shunt. A total of 128 intra-arterial SMANCS injection treatments, performed for 89 patients with hepatocellular carcinoma, were analyzed to determine the relationship between angiographic findings and subsequent hepatic vascular injuries. After SMANCS therapy, hepatic arterial stricture or obstruction occurred in 5 patients (5/128; 3.9%), arterio-portal shunting in 12 (12/128; 9.4%), liver shrinkage in 4 (4/128; 3.1%), and cholangitis or biloma in 2 (2/128; 1.6%). Among 23 patients whose plain abdominal X-ray films just after SMANCS injection showed Lipiodol retention in the hepatic artery, 5 patients developed arterial obstruction, 10 developed arterio-portal shunt, and 2, cholangitis or biloma. Among 26 patients with Lipiodol retention in the portal vein, 4 developed hepatic lobe atrophy with aggravation of liver function. Among 3 patients with Lipiodol retention in both the hepatic artery and the portal vein, 1 developed arterio-portal shunt. In 76 treatments without excessive Lipiodol retention, only 1 of the patients developed arterio-portal shunt. Excessive retention of Lipiodol in hepatic vascular beds just after SMANCS therapy was significantly associated with future vascular side effects (22/52 vs 1/76; P < 0.0001). Lipiodol retention in arteries just after SMANCS injection was closely associated with subsequent arterial obstruction or arterio-portal shunt, and Lipiodol retention in the portal vein was related to subsequent hepatic lobe atrophy.

Adult↗
PubMed2000

Progressive and sufficient decrease of hepatitis B core antibody can predict the disappearance of hepatitis B virus DNA in Japanese patients with hepatitis B surface antigen clearance.

The aim of this study was to elucidate the relationships among serum levels of hepatitis B virus (HBV) DNA, periods after hepatitis B surface (HBs) antigen clearance, and the titer of hepatitis B core (HBc) antibody in 200-fold diluted serum. Twelve patients who had clearance of HBs antigen from serum were studied. Five patients had not received any treatment (group A), and seven had received prednisolone withdrawal therapy. The patients in groups A and B were followed up for 86 months and 108 months (median), respectively. Serum HBV was measured by the nested polymerase chain reaction method. In both groups, serum HBV tended to become gradually undetectable after HBs antigen clearance. The positive rate of HBV in the sera 5 years or more after HBs antigen clearance was significantly lower than that in the sera at less than 5 years, both in group A (P = 0.004) and group B (P = 0.010). In both groups, the titer of HBs tended to decline every year after HBs antigen clearance. HBV was still detectable in the sera of some patients for a long period of time after they showed seroconversion to HBs antibody. The results suggest that detection of HBV was difficult in sera with an HBc titer of 30% or lower and at more than 5 years after HBs antigen clearance in both groups. It is important to note that HBV DNA rarely exists in the serum, even when HBs antigen and HBc are both negative.

Adolescent↗
PubMed2000

Increased response rate to interferon therapy after a second course in hepatitis C patients who show relapse after the initial course.

Some patients with chronic hepatitis C become HCV-RNA seronegative during interferon (IFN) therapy. However, about one-half of these patients show a relapse, evident by high serum alanine aminotransferase (ALT) level. In some patients with biochemical relapse, the serum HCV-RNA level becomes low immediately after the ALT relapse. Here, we assessed the changes in serum HCV-RNA level in patients with ALT relapse after IFN therapy, and evaluated the efficacy of a second course of IFN, started at the recovery stage after ALT relapse. Two hundred and seventy-seven patients who showed HCV-RNA seronegativity by reverse transcription nested-polymerase chain reaction (RT nested-PCR) and normalization of ALT during the initial IFN therapy, and had positive HCV-RNA with ALT relapse (> 100 IU/l) within 3 months after completion of the initial IFN course were enrolled in this retrospective study. Two hundred and sixty patients were followed-up without further IFN retreatment after the ALT relapse (group 1), and 17 patients received another 6-month course of IFN after the ALT relapse (group 2). The median level of serum HCV-RNA, determined with a branched DNA probe assay (version 1; Chiron-Dai-ichi Kagaku Tokyo, Japan), in group 1 was 3.1 Meq/ml before IFN therapy, 1.3 Meq/ml at the time point of the ALT peak after the completion of IFN therapy, and 0.7 and 2.6 Meq/ml at 2-4 and 6-8 weeks after the ALT peak, respectively. The serum HCV-RNA level at 2-4 weeks after the ALT peak was lower than that before IFN therapy. The eradication rate of HCV-RNA (complete response; CR) in group 2 (47.1%; 8/17) was significantly higher than that in group 1 (1.5%; 4/260; P < 0.001). In conclusion, our data suggested that: (1) patients who showed biochemical relapse after initial IFN therapy had a significantly lower serum HCV-RNA level at recovery after ALT relapse compared with that before initial IFN therapy. (2) A high response rate was noted after a second course of IFN administered at the recovery stage of the ALT relapse, compared with patients without IFN retreatment.

Adult↗
PubMed2000

LAT is essential for Fc(epsilon)RI-mediated mast cell activation.

The linker molecule LAT is a substrate of the tyrosine kinases activated following TCR engagement of T cells. LAT is also expressed in platelets, NK, and mast cells. Although LAT-deficient mice contain normal numbers of mast cells, we found that LAT-deficient mice were resistant to IgE-mediated passive systemic anaphylaxis. LAT-deficient bone marrow-derived mast cells (BMMC) showed normal growth and development. Whereas tyrosine phosphorylation of Fc(epsilon)RI, Syk, and Vav was intact in LAT-deficient BMMCs following Fc(epsilon)RI engagement, tyrosine phosphorylation of SLP-76, PLC-gamma1, and PLC-gamma2 and calcium mobilization were dramatically reduced. LAT-deficient BMMCs also exhibited profound defects in activation of MAPK, degranulation, and cytokine production after Fc(epsilon)RI cross-linking. These results show that LAT plays a critical role in Fc(epsilon)RI-mediated signaling in mast cells.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Distinction between chronic hepatitis and liver cirrhosis in patients with hepatitis C virus infection. Practical discriminant function using common laboratory data.

In order to distinguish patients with cirrhosis from those with chronic hepatitis, multivariate discriminant analysis was performed using common laboratory data. A total of 205 consecutive patients were diagnosed by peritoneoscopy and biopsy as having chronic liver disease caused by hepatitis C virus (HCV), 168 with chronic hepatitis and 37 with cirrhosis. Twenty variables and their natural logarithmic transformation were employed in the multivariate analysis. After stepwise variable selection, the following function was finally obtained to discriminate the disease severity, z=0.120xgamma-globulin (%)+0.423xln (hyaluronate) (µg l(-1))-0.059xplatelet (x10(4) counts per mm(3))-0.364xsex (male, 1; female, 2)-3.953. Since the function contained an expression of logarithm and was slightly troublesome to apply, we prepared another discriminant function composed of usual figures without logarithmic transformation, z=0.124x(gamma-globulin (%))+0.001x(hyaluronate) (µg l(-1))-0.075x(platelet (x10(4) counts per mm(3)))-0.413xgender (male, 1; female, 2)-2.005. When a positive result is calculated in the latter equation, the diagnosis of the liver disease indicates cirrhosis, and negative result chronic hepatitis. Accuracy of the two discriminant functions was 90.3 and 91.2%, respectively. A concise linear discriminant function could successfully differentiate liver cirrhosis from chronic hepatitis with an accuracy of 91.2%.

Journal Article↗
PubMed2000

Association of amino acid sequence in the PKR-eIF2 phosphorylation homology domain and response to interferon therapy.

Hepatitis C virus (HCV) genotype 1b and high pretreatment virus load are well known predictive factors of poor response to interferon (IFN) therapy. In addition, a sparsity of amino acid substitutions in the interferon sensitivity determining region (ISDR) is also predictive of a poor response to IFN in patients with genotype 1b, although this issue is still controversial. Recently, a 12 amino acid domain in the E2 protein of HCV (PKR-eIF2 alpha phosphorylation homology domain [PePHD]) has been reported to bind with and block the virus replication inhibition ability of PKR, suggesting that the interaction of E2 and PKR may be one mechanism by which HCV circumvents the antiviral effect of IFN. To clarify the significance of amino-acid sequences in this domain in predicting the effect of IFN therapy, we analyzed 82 patients with genotype 1b. Eleven patients (13.4%) responded to treatment whereas the remaining 71 patients (86.6%) were nonresponders. Multivariate analysis showed that only HCV load and amino-acid substitutions in the ISDR were predictive of sustained response to IFN. Amino-acid substitutions in the PePHD were detected in only eight of 82 patients (9.8%), and did not correlate with the therapeutic effect of IFN. However, amino-acid-sequence analyses of quasispecies before and after 1 week of IFN therapy showed elimination of clones with substitutions in this domain. Our results suggest that amino-acid sequences of the PePHD domain may be related to viral resistance to IFN but do not predict the outcome of IFN therapy as amino-acid substitutions in this domain are rare.

Adult↗