Biomedical subjects

T Ichikawa

Publications and source records attributed to T Ichikawa.

At least 145 records · Page 8Linked to original sources

PubMed1999

Activation of extracellular signal-regulated kinase in lung tissues of mice treated with carcinogen.

The activation of extracellular signal-regulated kinase (ERK) in lung tissues of mice, as determined by the appearance of phosphorylated form, was observed on day 30 after urethane injection, and the activation also occurred in urethane-induced lung tumors. Immunohistochemical analysis using anti-phosphorylated ERK antibody indicated that the active form of ERK localized in alveolar epithelial cells. Furthermore, we confirmed by immunoprecipitation and immunoblot analysis that other essential components of the ERK cascade, that is, Ras, Raf and MEK (known as ERK kinase) were activated. These results indicate that the activation of the ERK signal in alveolar epithelial cells at the early stage of urethane-induced lung carcinogenesis is an important factor to develop lung tumors.

Animals↗

PubMed1999

Stimulant effect of nitric oxide generator and roxatidine on mucin biosynthesis of rat gastric oxyntic mucosa.

Although the involvement of nitric oxide (NO) in an increasing gastric mucus metabolism has been reported, information on whether or not its activation is limited to the specific mucus-producing cells is lacking. In this paper, we report the effect of the exogenous NO-donor, isosorbide dinitrate (ISDN), and second-generation histamine H2 receptor antagonist roxatidine (2-acetoxy-N-(3-[m-(1-piperidinylmethyl)phenoxy]propyl)acetamide hydrochloride) which is demonstrated to accelerate the mucin metabolism mediated by endogenous NO, on the mucin biosynthesis in distinct sites and layers of the rat gastric mucosa using an organ culture technique. Radiolabeled mucin was obtained from the tissue of full-thickness and the deep corpus layer, and the antrum of the rat stomach incubated for 5 hr with [3H]glucosamine(GlcN) in vitro. With the addition of ISDN to the culture medium, 3H-labeled mucin in the full-thickness corpus mucosa increased to 124-145% of the control (p<0.05), but not in the antrum. This stimulation of the mucin synthesis disappeared by the removal treatment of the surface mucous cell layer which has immunoreactivity of neuronal NO synthase. Similarly, roxatidine stimulated the mucin biosynthesis in the full-thickness corpus mucosa, but not in the gland mucous cell layer. These results suggest that the stimulation of the mucin biosynthesis mediated by NO is restricted to the surface mucous cells of the rat gastric oxyntic mucosa.

Animals↗

PubMed1999

Unique behavioural phenotypes of recombinant-inbred CXBK mice: partial deficiency of sensitivity to mu- and kappa-agonists.

Recombinant-inbred CXBK mice have been used for various studies as putative mu-opioid-receptor deficient mice. However, CXBK mice have never been compared with gene-targeting mice lacking the mu-opioid receptor (muKO) and the K-opioid receptor (kappaKO). Here we report that CXBK mice show distinct behavioural phenotype in opioid-induced analgesia and sedation. Intraperitoneal (i.p.) administration of morphine (3 and 10 mg kg(-1)) induced significantly lower levels of analgesia in CXBK mice than in the control C57BL/6 mice, while higher doses of morphine (30 and 100 mg kg(-1)) induced marked analgesia in CXBK mice. CXBK mice also showed lower analgesia and sedation levels than did C57 mice after i.p. administration of U-50488 (10 and 30 mg kg(-1)). The partial deficiency of sensitivity to morphine and U-50488 of CXBK mice is in sharp contrast to the complete lack of sensitivity to morphine and U-50488 in muKO and kappaKO mice, respectively. Furthermore, CXBK mice showed a lower threshold for nociceptive stimuli when they were not given an opioid, suggesting that CXBK mice could have alterations in the genes related to the nociceptive threshold. These unique behavioural phenotypes of CXBK mice suggest unique genetic alterations in CXBK mice.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed1999

Fast magnetic resonance imaging of liver.

Recent magnetic resonance (MR) units with a stronger gradient system have allowed various fast MR imaging techniques to develop. These fast scan techniques have easily realized breath-holding acquisition in the liver and the image quality has been greatly improved without sacrificing spatial resolution. The majority of the fast imaging techniques have been devoted to T2-weighted imaging to obtain useful T2-weighted images in the shortest possible time. Among the fast sequences, fast spin-echo (FSE) sequence is the most promising technique and allows high-quality T2-weighted images with reduced motion artifacts. However, FSE sequences using multiple refocused pulses may essentially realize only poor soft-tissue contrast due to magnetization transfer and T2-filtering effects, and therefore, echo-planar (EP) imaging is expected to provide high image contrast. In addition, single-shot EP imaging allows even diffusion-weighted (DW) and perfusion-weighted (PW) imaging in the liver due to its short scanning time. Recent development of fast gadolinium-enhanced 3D MR angiography has also impacted liver imaging. Combined with such gadolinium-enhanced 3D-MRA sequences and zerofilling image interpolation technique, biphasic gadolinium-enhanced 3D-MRA (whole-liver dynamic MR imaging in the arterial phase and MR portography in the portal phase) can be obtained.

Contrast Media↗

PubMed1999

Polymorphisms of the CYP1A1 and GSTM1 gene involved in oral squamous cell carcinoma in association with a cigarette dose.

The genetic polymorphisms of CYP1A1 and GSTM1 genes among 100 Japanese patients with oral squamous cell carcinomas (SCC) were investigated to evaluate the role of genetic susceptibility in carcinogenesis of the oral cavity. The presence of the rare homozygote of CYP1A1, m2/m2, was significantly more frequent in the patient group (15.0%) than the control group (8.0%) (Odds ratio (ORs) = 3.6 95% Confidential Interval (CI): 1.4-9.5). The heterozygotic variant, m1/m2, was also frequently seen in oral SCC patients. This meant that the m2 allele was observed in more than half of the patients. The null genotype of GSTM1 was found in 43.0% of the patient group. This was not significantly different from the controls (40.0%). When the life time cigarette consumption dose of the patients was considered with respect to genotypes of CYP1A1, the mean smoking index (SI) of oral SCC patients with m2/m2 was found to be less than half of the mean SI among the patients with m1/m1 genotype (P < 0.02). The ORs of the m2/m2 genotype was found to be significantly high in a comparison of various subsites of the oral cavity, except for the floor of the mouth. Our results indicate that the rare homozygote of CYP1A1, m2/m2, is associated with increased risk of oral SCC, in particular, at low cigarette dose levels. The results also suggested that the involvement of such susceptibility in oral carcinogenesis might be different between the subsites of the oral cavity.

Adult↗

PubMed1999

Three-dimensional bone structure around hydroxyapatite and titanium implants in rabbits.

Long-term support of dental implants requires adequate bone thickness in the area surrounding the implant. A three-dimensional examination, including calculations of percent bone-implant contact and percent bone volume, was conducted to clarify the bone structure around pure titanium (Ti) and dense hydroxyapatite (HA) implants. The implants were installed in the tibiae of rabbits, and the bone structure was examined after 2, 4, 6 and 8 weeks. The bone formation following implantation differed in the cortical bone and cancellous bone areas. In the cortical bone area, the percent bone-implant contact and percent bone volume were comparatively consistent for both Ti and HA implants during the observation period. In the cancellous bone area, both findings were influenced by the implantation period, and the chronological bone structure in the cancellous bone area also differed between Ti and HA implants. The percent bone-implant contact and percent bone volume in the Ti implant increased over 8 weeks, whereas the dense HA implant increased for the first 4 weeks and then decreased. The implant materials, Ti and HA, affected the bone remodeling in the cancellous bone area.

Analysis of Variance↗

PubMed1999

Oncolytic virus therapy of multiple tumors in the brain requires suppression of innate and elicited antiviral responses.

The occurrence of multiple tumors in an organ heralds a rapidly fatal course. Although intravascular administration may deliver oncolytic viruses/vectors to each of these tumors, its efficiency is impeded by an antiviral activity present in complement-depleted plasma of rodents and humans. Here, this activity was shown to interact with complement in a calcium-dependent fashion, and antibody neutralization studies indicated preimmune IgM has a contributing role. Short-term exposure to cyclophosphamide (CPA) partially suppressed this activity in rodents and humans. At longer time points, cyclophosphamide also abrogated neutralizing antibody responses. Cyclophosphamide treatment of rats with large single or multiple intracerebral tumors substantially increased viral survival and propagation, leading to neoplastic regression.

Animals↗

PubMed1999

Reactive oxygen species influence the acrosome reaction but not acrosin activity in human spermatozoa.

It is now widely accepted that the higher levels of reactive oxygen species (ROS) produced by damaged or deficient spermatozoa are associated with a loss of motility and a decreased capacity for sperm-oocyte fusion. Furthermore, earlier studies show, under physiological conditions, that some ROS may be involved in capacitation and hyperactivation of human spermatozoa. We measured ROS levels, acrosome reaction (AR) and acrosin activity (AA) in semen samples from suspected subfertile men to reveal the influence of ROS on AR and AA of human spermatozoa. Semen samples were obtained from 60 patients. Samples with > or = 1 x 10(6) leukocytes/mL were excluded from the study. ROS production was determined using a chemiluminescence technique. AR was determined using a triple stain technique. The percentage of acrosome-reacted spermatozoa after low temperature induction of the AR (test value), and the inducibility of AR (= the difference between the test value and the control), were calculated. The AA was analysed by determining the proteolytic potential of spermatozoa on gelatin plates. The mean halo diameter and percentage of halo formation in each sample were measured as AA parameters. Scatter plots of ROS levels and AR parameters showed that the percentage of acrosome reacted spermatozoa and AR inducibility were better in samples with low rather than high ROS levels. On the other hand, there were no apparent similarities between ROS and the AA parameters. Therefore, the percentage of acrosome-reacted spermatozoa and AR inducibility were significantly higher in the low than in the high ROS group (p = 0.028, p = 0.0001, respectively). In addition, there was no significant difference in AA parameters between groups. These findings suggest that lower ROS in semen may have a role in AR but excessive ROS may exert a negative influence on AR, while ROS in semen has no relationship to AA.

Acrosin↗

PubMed1999

Influence of lining design of three processed soft denture liners on cushioning effect.

The purpose of this study was to evaluate the influence of the lining design of a soft denture liner on its cushioning effect, using a free drop test and an accelerometer. The peak instantaneous acceleration value was computed. The materials tested were SuperSoft(R) (SS), Kurepeet-Dough(R) (KD), and Molloplast-B(R) (MB). Soft denture liners 2 mm in thickness were placed in test denture bases using three different configurations. Specimens were tested at 24 h and at 180 days after storage in distilled water at 37 degrees C. A three-way ANOVA was used to analyse the data (P=0.05) and Tukey intervals were computed. It was found that all three materials were effective in reducing the impact force. The lining design that had the soft denture liner extended to the periphery of the denture base demonstrated the greatest shock absorbability of all the tested designs. A silicone denture liner using lining design 1 was the most effective in reducing the shock transmitted to the denture bases.

Acceleration↗

PubMed1999

Evaluation of twice-daily administration of interferon-beta for chronic hepatitis C.

To improve the efficacy of interferon (IFN) in the treatment of chronic hepatitis C, administration of IFN-beta twice per day was evaluated. Thirty-eight patients with chronic hepatitis C (26 males and 12 females, aged 25-67 years) were included. Patients were treated with a new protocol that included twice-daily treatment with IFN-beta. Three million units (MU) of IFN-beta was administered twice daily every day for 4 weeks followed by 10 MU of IFN-alpha2b, every day for 2 weeks and then three times a week for 18 weeks (total IFN-beta, 148 MU; IFN-alpha2b, 680 MU). Complete responders (CR) were defined by alanine aminotransferase levels that normalized within 6 months after completion of IFN therapy and remained normal for more than 6 months, and by serum hepatitis C virus (HCV) RNA levels that became negative as determined using the Amplicor assay. Twenty-one of 38 (55.3%) patients were CR. Nine of 21 (42.9%) patients with HCV serotype 1 were responders compared with nine of 12 (75.0%) patients with HCV serotype 2. In patients with an HCV titre greater than 1 million equivalents ml-1 (1 MEq ml-1), nine of 24 (37.5%) responded, and in patients with HCV titres less than 1 MEq ml-1, 12 of 14 (85.7%) responded. In patients with HCV serotype 1 and greater than 1 MEq ml-1 HCV RNA, four of 15 (26.7%) responded to IFN. Two-thirds (66.7%) of the patients who became negative for HCV RNA after 2 weeks of therapy responded, while 72.7% of those with positive HCV RNA after 2 weeks of therapy were non-responders. Proteinuria was frequently observed as an adverse effect of twice-daily administration of IFN-beta. The combination of twice-daily administration of IFN-beta for 4 weeks followed by IFN-alpha showed a high response rate in patients with chronic hepatitis C, but in patients with both serotype 1 and a high titre of HCV RNA, response rates were still low. Thus, the HCV RNA titre 2 weeks after starting therapy with IFN was useful for predicting the eventual response to IFN.

Adult↗

PubMed1999

External beam radiation monotherapy for prostate cancer.

BACKGROUND: To clarify the implications and limitations of external beam radiation monotherapy for localized prostate cancer, the long-term outcomes and prognostic factors were investigated. METHODS: Between 1976 and 1994, 91 patients with untreated prostate cancer were treated with external beam radiation therapy alone. Thirty-two were classified as T1b, eight were T2a, four were T2b and 47 were T3. Pelvic lymphadenectomy was carried out in 69 cases; 57 were staged as pN0, eight were pN1, four were pN2 and 22 were pNX. Linac X-rays were used in 55 cases, fast neutron in 15 and a combination of the two in 21. No other therapy was given until relapse and when relapse was evident endocrine therapy was started. RESULTS: The observation period ranged from 3 to 206 months with a median of 78 months. Local control rate and disease-free, cause-specific and overall survivals at 10 years were 74.0, 49.6, 74.2 and 39.2%, respectively. By univariate analysis, T category, pN category and histologic grade were significant prognostic indicators for disease-free survival. Multivariate analysis revealed that T category was an independent prognostic factor. In T2b and T3 diseases, pN0/1 patients demonstrated significantly better disease-free survival than pNX. CONCLUSIONS: A favorable long-term outcome was achieved by external beam radiation monotherapy in patients with minimally extended prostate cancer (T1b and T2a). For locally advanced disease (T2b and T3), staging pelvic lymphadenectomy would be useful for the selection of patients.

Adenocarcinoma↗

PubMed1999

Radiotherapy for local progression in patients with hormone-refractory prostate cancer.

PURPOSE: The aim of the present study was to investigate the effect of radiotherapy on the local progression of hormone-refractory prostate cancer. METHODS: From 1986 to 1995, 38 patients were diagnosed with local progression without distant progression after hormonal therapy at Chiba University Hospital. Eleven cases were treated with irradiation for local progression. External beam irradiation was delivered to the prostate at a dose of 50-66.6 Gy. RESULTS: In patients treated with radiotherapy, the duration from initial treatment to local recurrence was 6-80 months (mean +/- SD: 33.9 +/- 22.9 months). The follow-up period after irradiation was 7-64 months (mean +/- SD; 25.4 +/- 18.8 months). Three and 5 year cause-specific survival rates from radiotherapy were 46.2 and 23.1%, respectively. Radiotherapy had a marked effect on symptoms associated with local progression and no patients suffered from the symptoms after the radiotherapy. Complications of radiotherapy were limited. CONCLUSIONS: In patients with hormone refractory local progression without distant progression, low morbidity, low mortality radiotherapy offers a variable therapy to other palliative treatments because radiotherapy is able to control local symptoms for a long period of time.

Aged↗

PubMed1999

Prognosis of patients with T4 prostate carcinoma.

BACKGROUND: The clinical course of patients with T4 prostate carcinoma was examined in order to consider whether there are alternative treatment options besides androgen ablation therapy. METHODS: From 1986 to 1995 at Chiba University Hospital, there were 22 cases of T4 prostate carcinoma. Sixteen cases had no bone metastasis at initial diagnosis. Tumor grade and response of prostate-specific antigen (PSA) to endocrine treatment were evaluated in these 16 cases. RESULTS: Four patients had moderately differentiated and 12 had poorly differentiated adenocarcinoma. For initial treatment, all patients received endocrine therapy. Anti-androgen therapy was effective in 15 cases and the 5 year cause-specific and progression-free survival rates were 72.1 and 38.1%, respectively. Patients with moderately differentiated tumors tended to have a longer disease-free period than those with poorly differentiated tumors (P = 0.047). CONCLUSIONS: Endocrine therapy was effective in patients with T4 tumors. It was suggested that aggressive local treatment (i.e. radiotherapy) in combination with endocrine therapy may be considered if the patients had no distant metastases and had a long life expectancy.

Adenocarcinoma↗

PubMed1999

Increased synthesis of hyaluronate enhances motility of human melanoma cells.

Hyaluronate plays a unique role in the cancer cell microenvironment. In particular, melanoma is the tumor type in which hyaluronate and hyaluronate recognition have been most closely linked to malignancy. In this study we show that a human melanoma cell line stably transfected with hyaluronate synthase cDNA displays enhanced motility. We used a fixed erythrocyte exclusion assay to isolate subsets of the WM793 human melanoma cell line that expressed either high or low amounts of hyaluronate. A cell line with a high level of hyaluronate on its surface (WM793H) displayed significantly higher cell motility on colloidal-gold-coated coverslips than did a line with a low level (WM793L). Next, in order to directly investigate the effects of hyaluronate on melanoma cell migration, we transfected cDNA encoding mouse hyaluronate synthase HAS1 or HAS2 into the re-cloned human melanoma cell line that produced a low amount of hyaluronate (WM793L) by the lipofection method. Several clonal transfectants differentially producing hyaluronate were obtained. There was a positive correlation between total hyaluronate synthesis and formation of the pericellular hyaluronate-rich matrix. We observed an increase in the migration ability of hyaluronate cDNA (HAS1 or HAS2)-transfected cells compared with control cells on glass plates covered with colloidal gold particles. A migration-inhibition assay with anti-CD44 monoclonal antibody showed blocking of the cell motility. It is speculated that the tumor cells might migrate through a hyaluronate-rich extracellular environment when they invade nearby host tissues and that hyaluronate production by the tumor cells could increase this migration. These results suggest that hyaluronate may play a role in the aggressiveness of human melanoma cells.

Animals↗

PubMed1999

Complete dislocation of the trapezium. Case report.

A 24-year-old woman presented with complete, closed dislocation of the trapezium after a skiing accident. Treatment by closed reduction and fixation with a Kirschner wire gave an excellent clinical result with early return to full function. There were no radiological signs of arthrosis or avascular necrosis at 2 years follow-up.

Adult↗

PubMed1999

Rare-type mutations of MMAC1 tumor suppressor gene in human glioma cell lines and their tumors of origin.

A total of 10 glioma cell lines were examined to evaluate the status of the MMAC1 gene, a candidate tumor suppressor gene. Six cell lines showed mutations with presumed loss of heterozygosity and 1 cell line showed no mRNA expression. The 6 mutations consisted of 3 3-bp deletions (codons 17, 101 or 199), 1 missense mutation (codon 252) and 2 truncation mutations (1 nonsense mutation at codon 233 and 12-bp insertion at codon 241). Among them, the 3-bp deletions, which are a rare type of mutation in MMAC1 gene, were located in the N-terminal half (codons 1-212) of the coding region, which is considered important in MMAC1 function. The missense mutation was located unusually in the C-terminal half (codons 212-403), but it was in a small region in which some other reported missense mutations are clustered. Thus, these 4 mutations were suggested to have functional effects on the MMAC1 activity, like the other 2 mutations with predicted protein truncations. By sequence analysis of cDNA clones, we confirmed that all the mutations including these 4 rare ones were in the MMAC1 gene, not in the PTH2 pseudogene. In 2 cases, we also examined the primary glioma tissues from which the cell lines had been derived and found the same mutations as in the cell lines in both cases. This suggested that the mutations in these cell lines were derived from the primary glioma tissues, but not from artifacts arising during long-term in vitro cultivation.

Adult↗

PubMed1999

Fibrolamellar hepatocellular carcinoma: imaging and pathologic findings in 31 recent cases.

PURPOSE: To review characteristic findings of fibrolamellar hepatocellular carcinoma (HCC) at computed tomography (CT) and magnetic resonance (MR) imaging. MATERIALS AND METHODS: The authors retrospectively reviewed the clinical, pathologic, and preoperative imaging findings in 31 patients with histologically proved fibrolamellar HCC. Dynamic contrast material-enhanced CT of the liver was performed in 31 patients, helical multiphase CT in 21, and MR imaging in 11. Complete resection was performed in 17 patients, and imaging-pathologic correlation was performed. RESULTS: Large tumors (mean diameter, 13 cm) were depicted at CT and MR in all cases. At CT, the margins of the tumors were well defined in 24 (77%) of 31 cases calcifications were depicted in 21 (68%), a central scar in 22 (71%), and abdominal lymphadenopathy in 20 (65%). In 20 (80%) of 25 cases with hepatic arterial phase CT images, all tumors were heterogeneous and depicted areas of hypervascularity. At MR imaging, tumors were hypointense to liver on T1-weighted images (n = 11) and hyperintense to liver on T2-weighted images (n = 10). Calcification was not depicted on MR images, but a central scar was depicted as hypointense to surrounding tumor in nine cases. CONCLUSION: CT and MR images demonstrate characteristic features that may allow confident diagnosis of fibrolamellar HCC.

Adolescent↗

PubMed1999

Prevalence of hepatitis G virus in liver disease.

The prevalence of hepatitis G virus (HGV) in liver disease of non-A, -B, -C viral hepatitis, hepatitis B and hepatitis C was determined. Two of 44 patients (4.5%) with liver injury without any hepatitis A, B or C marker were positive for HGV. One of five cases of hepatocellular carcinoma was positive for HGV. One of three cases with fulminant hepatitis was positive for HGV. This case was negative at the onset of fulminant hepatitis and became positive after plasmapheresis. No patient with acute (n=8) or chronic (n=5) hepatitis or liver cirrhosis (n=8) was positive for HGV in non-A, -B, -C liver disease. One of 30 patients with various HBV-positive liver diseases and nine (17.3) of 52 patients with type C liver disease were positive for HGV. In patients with hepatitis C, four (28.6%) of 14 HGV-co-infected patients were complicated with diabetes mellitus compared with four (10.5%) of 38 single hepatitis C virus (HCV)-infected patients (not significant). In 12 HGV-positive patients, eight of 10 (80%) had a history of blood transfusion. In HCV-positive patients, co-infection with HGV was not a risk factor in patients with diabetes mellitus as a complication. HGV appeared to cause non-A, -B, -C hepatitis rarely, and its main route of infection was blood transfusion.

Adolescent↗