Biomedical subjects

M Kobari

Publications and source records attributed to M Kobari.

At least 37 records · Page 2Linked to original sources

PubMed1999

Genomic analysis of the thymine-DNA glycosylase (TDG) gene on 12q22-q24.1 in human pancreatic ductal adenocarcinoma.

CONCLUSION: Abnormality of the thymine-DNA glycosylase (TDG) gene on 12q22-q24.1 appears to play a limited role in pancreatic ductal carcinogenesis. BACKGROUND: Recently, a human G/T-specific TDG gene was identified. This protein acts in a system correcting G/T mispairs to G/C pairs. TDG was mapped to chromosome bands 12q22-q24.1, one of the regions frequently lost in pancreatic cancer. Therefore, there is the possibility that the TDG gene on 12q is one of the genes responsible for pancreatic ductal carcinogenesis. METHODS: Nucleotide sequences of the entire coding region of the TDG gene were analyzed in 21 human pancreatic cancer cell lines. mRNA expression of the TDG gene was also analyzed by Northern hybridization in several human tissues and 21 human pancreatic cancer cell lines. RESULTS: Decreased levels of mRNA expression were detected in the pancreatic cancer cell lines, but no somatic mutations were observed.

Adenocarcinoma↗

PubMed1999

Preventing effect of anti-ICAM-1 and anti-LFA-1 monoclonal antibodies on murine islet allograft rejection.

Immunosuppressive potentials of the blockade of intercellular adhesion molecule-1 (ICAM)-1/leukocyte function-associated antigen 1 (LFA-1) were examined in a murine islet allotransplantation model by using blocking monoclonal antibodies (MAbs) against these molecules. Isolated islets from ICR mice were transplanted into the renal subcapsular space of streptozotocin-induced diabetic C57BL/6 mice. Antibodies were administered immediately after transplantation at a dose of 100 micrograms/mouse/d for 3 or 7 d. In non-treated mice, islet grafts were rejected within 16 d, but the treatment with an anti-ICAM-1 MAb (KAT-1) alone, with anti-LFA-1 MAb (KBA) alone, or with both MAbs significantly prolonged the graft survival. In particular, the combination of KAT-1 and KBA in a 7-d course produced a marked prolongation and induced indefinite graft survivals over 100 d in 88% of recipients. Expression of cytokine transcripts within the islet allografts was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR). In the mice treated with KAT-1 and KBA, the transcripts for Th1 cytokines (interleukin 2 [IL-2] and interferon gamma [IFN-gamma]) were not detected, but the expression of Th2 cytokines (IL-4 and IL-10) was enhanced and persisted over 140 d. In contrast, Th1 cytokines were dominantly expressed in the grafts from untreated mice. These results indicate that administration of anti-ICAM-1 and/or anti-LFA-1 MAbs prolongs murine islet allograft survival potentially by indicating a Th2 deviation.

Animals↗

PubMed1999

Adjuvant immunotherapy using fibroblasts genetically engineered to secrete interleukin 12 prevents recurrence after surgical resection of established tumors in a murine adenocarcinoma model.

BACKGROUND: To explore effective therapeutic strategy against cancer of the gastrointestinal tract, tumor vaccination using fibroblasts secreting interleukin-12 (IL-12) was developed as an adjuvant therapy against murine tumor after surgical resection. METHODS: Initially, IL-12 was genetically engineered into fibroblasts (IL-12/3T3 cells), and then we evaluated in vivo and in vitro antitumor effects. In the vaccination model, irradiated C-26 tumor mass was reinoculated intradermally with IL-12/3T3 cells in mice as a tumor vaccine to examine how much it suppresses tumor recurrence. RESULTS: IL-12/3T3 cells producing 7.2 ng/10(6) cells/24 h murine IL-12 in vitro exerted dose-dependent potent tumor suppression when coinoculated with C-26 cells in vivo. Specific immunity was also acquired in 63% of mice in vivo. In the vaccination model, protective immunity was developed in 70% of mice that were inoculated with irradiated tumor mass and IL-12/3T3 cells. In addition, local recurrence was not observed in vaccinated mice, although 44% of control mice had recurrence. CONCLUSIONS: Coinoculation of genetically engineered fibroblasts secreting IL-12 with irradiated tumor mass was proved to be an effective tumor vaccine. This system of vaccination is easily applicable to clinical situations, particularly to human gastrointestinal tract cancers.

Adenocarcinoma↗

PubMed1999

Identification of three commonly deleted regions on chromosome arm 6q in human pancreatic cancer.

Pancreatic cancer has one of the poorest prognoses among malignant diseases. To understand its molecular mechanisms, we studied allelic losses on the long arm of chromosome 6. Using 55 paired DNAs of tumors and their corresponding normal tissues and 30 microsatellite markers that spanned the entire 6q chromosome arm, we found three distinct regions of common allelic loss: region A, a less than 500-kb region bordered by D6S449 and D6S283 on 6q21 with a loss of heterozygosity (LOH) frequency of 69% (38/55); region B, a 7-cM region bordered by D6S292 and D6S308 on 6q23-q24 with a LOH frequency of 60% (33/55); and region C, a 13-cM region bordered by D6S305 and D6S264 with a LOH frequency of 51% (28/55). We further focused on region A and constructed a physical map using yeast artificial chromosome (YAC) clones, their derived cosmid clones, and bacterial artificial chromosome (BAC) clones. Region A was completely covered by three overlapping BAC clones. Our results in the present study should shed light on the cloning and characterization of tumor suppressor genes in pancreatic carcinogenesis.

Adult↗

PubMed1999

[Therapeutic strategy for the recurrence of pancreatic cancer following pancreatectomy].

It is well-known that the patients with pancreatic cancer are vulnerable for recurrence such as local relapse and liver metastasis after surgical resection. We revealed that a patient with local relapse without liver metastasis showed better prognosis as compared with a patient having liver metastasis. We usually adapt further therapeutic intervention for local recurrence using external radiation therapy accompanied with 5FU infusion as a radiosensitizer, if the patient is not revealed with liver metastasis. On the other hand, there is no effective intervention for liver metastasis accompanying pancreatic cancer, as small lesions of multiple liver metastases progress rapidly. We insert the tip of catheter in proper hepatic artery in order to infuse MMC once a week at outpatient clinic. However, we were not yet able to evaluate the effect of arterial infusion therapy.

Infusions, Intra-Arterial↗

PubMed1999

Total number and size distribution of hepatic metastases of carcinoma.

OBJECTIVE: To quantify the susceptibility of carcinoma to hepatic metastases by studying autopsy livers with carcinoma metastases, the primary sites of which were mostly the digestive organs. STUDY DESIGN: We developed a stereologic method of estimating the total number, N, and the size distribution of metastatic tumors in the liver based on a geometric model of spherical nodules with varying radii, r. This method proved to be sufficiently reliable by disector analysis simultaneously performed in some cases; it gave an approximate result. This method was applied to the 31 autopsy cases. Correlation and regression analyses were performed among N, the mean radius of nodules, rmean, and conventional pathologic features of the primary tumor. RESULTS: The estimates of N ranged from 10 to 3.2 x 10(5). A close negative correlation was confirmed between N and rmean. Neither significant correlation nor regression was observed among N and the other pathologic factors of the primary tumors. CONCLUSION: N turned out to serve as a useful index for evaluating the metastatic potential of a carcinoma. However, investigation has yet to be made to determine biologic factors in the primary tumor closely associated with N.

Carcinoma↗

PubMed1998

Loss of chromosome 18q is an early event in pancreatic ductal tumorigenesis.

Cytogenetic and molecular studies demonstrated that pancreatic cancer frequently shows specific chromosomal abnormalities, such as losses of 9p, 17p, and 18q, and gains of 8q and 20q. We have analyzed alterations in the copy number of specific chromosomal regions in cells from the pancreatic juices of 32 patients with various pancreatic disorders by fluorescence in situ hybridization (FISH) technique to pursue the possible clinical use of early diagnosis of pancreatic cancer. None of the chromosomal abnormalities were found in 13 specimens from individuals who had no neoplastic lesions. On the other hand, 12 specimens (63%) derived from the remaining 19 patients who had neoplastic lesions showed at least one chromosomal abnormality. Ten of these specimens were from pancreatic cancer patients; 7 cases (70%) showed chromosomal abnormalities. All but one of the 12 tumors with chromosomal abnormalities had loss of 18q. Furthermore, we detected a tumor in one patient in whom the routine cytological method and endoscopic retrograde chorangiopancreatography found nothing. Based on the results by FISH, we performed endoscopic ultrasonography and found a small serous cystadenoma in this patient. These results indicate that: (a) FISH analysis of cells from pancreatic juices obtained during endoscopic retrograde chorangiopancreatography is quite useful for detecting pancreatic ductal tumors; and (b) loss of chromosome 18q is one of the early genetic changes that provide very useful information in diagnosing pancreatic neoplasias.

Adolescent↗

PubMed1998

Identification of two common regions of allelic loss in chromosome arm 12q in human pancreatic cancer.

Using the method of microsatellite analysis, we studied 40 tissues with pancreatic ductal adenocarcinoma and identified two commonly deleted regions on the long arm of chromosome 12. One (region A) was found between D12S81 and D12S1719 at 12q21 at a frequency of 67.5%, and the other (region B) was located between D12S360 and D12S78 at 12q22-q23.1 at a frequency of 60%; the latter was reported previously (M. Kimura, et al. Genes Chromosomes Cancer, 17: 88-93, 1996). The results of microsatellite analyses were verified by fluorescence in situ hybridization. We further analyzed 19 pancreatic cancer cell lines by fluorescence in situ hybridization and found that 10 of them showed allelic loss at D12S81 and 6 showed allelic loss at D12S360. Yeast artificial chromosome contigs were constructed to cover the deleted regions. Region B was completely covered by a 650-kb yeast artificial chromosome clone. The frequently deleted regions in chromosome 12q in pancreatic cancer that were identified here may provide new avenues for isolating novel tumor suppressor genes.

Adult↗

PubMed1998

Hydrogen peroxide enhances phagocytic activity of ameboid microglia.

Microglia are considered to serve as a guardian of the brain. In achieving this task, they have been observed to transform into a reactive form and then an ameboid form. Several substances are implicated in the control of such behavior. We examined the effect of hydrogen peroxide on cultured microglia of ameboid form obtained from the fetal rat brain employing video-enhanced contrast-differential interference contrast microscopy. Microglia harvested from the culture bottle were observed to float in a spherical shape with abundant filopodia on the surface. However, on coming into contact with the glass surface of a cover slip, they immediately transformed into an ameboid form. The microglia spread themselves out, surrounded by thin transparent lammellipodia, which would not be clearly observable by either light microscopy or electron microscopy. In a concentration-dependent fashion, 10(-3)-10(-1) M hydrogen peroxide solution enhanced the ruffling process of the lamellipodia and formation of vesicles (phagosomes), which displayed a typical phagocytotic form. It is concluded that an increase in free radicals in ischemic tissue tends to facilitate the phagocytosis of ameboid microglia as macrophages.

Animals↗

PubMed1998

The inhibitory effect of an EGF receptor-specific tyrosine kinase inhibitor on pancreatic cancer cell lines was more potent than inhibitory antibodies against the receptors for EGF and IGF I.

CONCLUSION: Epidermal growth factor (EGF) increased the cell number of the two pancreatic cancer cell lines, MiaPaCa-2 and LN-36, in vitro. A blockade of the EGF-R tyrosine kinase with tyrphostin was more efficient in reducing the cell number than inhibiting receptor antibodies. IGF-1 increased the cell number, and blockade of the IGF-1-R initially decreased the cell number that later was followed by an increase in LN-36. BACKGROUND/AIM: The receptors and ligands of EGF and insulin-like growth factor-1 (IGF-1) are overexpressed in pancreatic cancer tissue. The aim of the present experiments was to study the effects of EGF and IGF-1 on the cell number in two pancreatic cancer cell lines. MATERIAL AND METHODS: MiaPaCa-2 cells were grown in 0.2% fetal calf serum (FCS) and the newly established LN-36 cells in serum-free medium (SFM). The cell number was measured with the XTT method. The effects of EGF and IGF-1 were studied in combination with inhibiting receptor antibodies and an EGF-R-specific tyrosine kinase inhibitor, tyrphostin B56. RESULTS: MiaPaCa-2 responded with increased cell number to stimulation with EGF, and at 10(-8) M or higher concentrations a dose-response pattern was seen. Administration of B56 to MiaPaCa-2 decreased the cell number by 87%. The inhibiting EGF-R-Ab only inhibited EGF-induced increase in cell number. IGF-1 doubled the cell number of MiaPaCa-2 and increased the cell growth induced by EGF. The inhibiting IGF-1-R-Ab reduced the cell number by 10%. The LN-36 cell line responded to EGF with an increased cell number with a maximum at 5 x 10(-9) M after 96 h. B56 reduced the cell number by 90% at 10(-5) M, with less effect during stimulation with EGF. In contrast to B56, the inhibiting EGF-R-Ab in the same experiment did not reduce the cell number. LN-36 responded to IGF-1 with an increased cell number, but EGF-stimulated growth was not influenced. The inhibiting IGF-1-R-Ab reduced the cell number and suppressed the IGF-1 stimulated increase after 24 h and later it induced an increased cell number.

Antibodies↗

PubMed1998

Pancreatic microcirculation in acute pancreatitis.

We present a review of the microvascular morphology of the pancreas and microstructure of the pancreatic lobule, and report our experimental results of the investigation of pancreatic microcirculation following acute pancreatitis. Impairment of pancreatic microcirculation in the early phase of acute pancreatitis may play a key role in the progression of this disease. Possible contributory mechanisms include increased vascular permeability, reduced blood flow, leukocyte-endothelial cell interaction and intravascular thrombus formation. Using an in-vivo microscope system and off-line computer analysis, we achieved direct visualization and quantification of changes in microvascular permeability and leukocyte behavior in pancreas with acute pancreatitis. Bradykinin and oxygen radicals have been demonstrated to be involved in the increase of vascular permeability in the early stage of caerulein pancreatitis. Leukocyte adherence to the vessels in the pancreatic microcirculation is a secondary event following permeability changes in acute pancreatitis. Leukocyte infiltration during exacerbation of acute pancreatitis is mediated by leukocyte-endothelial cell interaction via leukocyte integrin CD11b/18.

Acute Disease↗

PubMed1998

Staging systems for pancreatic cancer: differences between the Japanese and UICC systems.

Differences between the clinical staging system of the Japan Pancreas Society (JPS) and the Union Internationale Contre le Cancer (UICC) stage classification may account for reported differences in the prognosis of pancreatic carcinoma between Japan and the West. In the review, we compared the characteristics of the JPS and UICC staging in 1689 patients, registered with the JPS from 1981 to 1990, who underwent resection for carcinoma of the pancreatic head. The survival rates correlated well with the JPS stage classification. The UICC staging did not reflect differences in prognoses among the stages. The current JPS staging system, introduced in 1993, still differs from that of the UICC. To compare the results of treatment for patients with pancreatic cancer it is important to establish a more practical and universal staging system for carcinoma of the pancreas.

Humans↗

PubMed1998

Intraoperative radiotherapy for pancreatic adenocarcinoma.

Intraoperative radiotherapy (IORT) is an innovative treatment approach for cancer of the pancreas. The common causes of treatment failure in pancreatic cancer are regional recurrence and distant metastasis. While at present the benefit of IORT in unresectable pancreatic cancer is still controversial and awaits further prospective trials for its clarification, the experience gathered over a period of 30 years with IORT for pancreatic cancer does suggest that IORT should be part of the adjuvant therapy of surgical resection. A combination with pre- or postoperative external beam radiotherapy and chemotherapy may be beneficial for both resectable and unresectable patients. IORT was shown to be a relatively safe intervention and it notably improved the quality of life of patients with locally advanced pancreatic carcinomas by alleviating their pain. Here, we summarize and discuss the experience reported to date and present our historical analysis of IORT for pancreatic cancer.

Adenocarcinoma↗

PubMed1998

Comparative phenotypic studies of duct epithelial cell lines derived from normal human pancreas and pancreatic carcinoma.

We have investigated the mRNA/protein expression of several tyrosine kinase receptors, growth factors, and p16INK4A cyclin inhibitor in cell lines derived from normal human pancreatic duct epithelium (HPDE) and compared them with those of five pancreatic ductal carcinoma cell lines. Cultured HPDE cells express low levels of epidermal growth factor receptor (EGFR), erbB2, transforming growth factor (TGF)-alpha, Met/hepatocyte growth factor receptor (HGFR), vascular endothelial growth factor (VEGF), and keratinocyte growth factor (KGF). They also expressed high levels of amphiregulin but did not express EGF and cripto. The expression levels were similar in primary normal HPDE cells and those expressing transfected E6E7 genes of human papilloma virus-16, but their immortalization appeared to enhance the expression of EGFR and Met/HGFR. In comparison, pancreatic carcinoma cell lines commonly demonstrated overexpression of EGFR, erbB2, TGF-alpha, Met/HGFR, VEGF, and KGF, but they consistently showed marked down-regulation of amphiregulin mRNA expression. In contrast to all carcinoma cell lines that showed deletions of the p16 gene, HPDE cells consistently demonstrated normal p16 genotype and its mRNA expression. This is the first report that compares the phenotypic expression of cultured pancreatic ductal carcinoma cells with epithelial cell lines derived from normal human pancreatic ducts. The findings confirm that malignant transformation of human pancreatic duct cells commonly results in a deregulation of expression of various growth factors and receptors.

Adenocarcinoma↗

PubMed1998

Criteria for diagnosis of acute pancreatitis in Japan and clinical implications.

The Japanese grading system for severity of acute pancreatitis has evolved from results of a national survey on 2,553 patients managed in 523 major medical centers in Japan between 1982 and 1986. It was devised to embrace the predictive factors that would offer high sensitivity and specificity in rendering an accurate diagnosis. In this system, computed tomographic (CT) examination is used for estimating the severity of acute pancreatitis. Combining criteria from laboratory data, clinical signs, and CT findings, the system appears cumbersome. However, it is actually more flexible in that only few criteria, from the wide range of findings actually covered, are needed to predict severity. Its rationale stems from a national effort to improve the outcome of this life-threatening disease. Further prospective studies are needed to determine its accuracy and superiority.

Acute Disease↗

PubMed1998

Surgical aspects and management of acute necrotizing pancreatitis: recent results of a cooperative national survey in Japan.

A cooperative national survey between 1991 and 1994 recently clarified the status of acute necrotizing pancreatitis in Japan. The overall mortality rate was 20.8%; however, the mortality rate in patients with infection was 33.3%, and the mortality rate in patients who underwent surgery was 27.4%. With regard to surgical procedures, drainage procedures (mobilization of the pancreatic bed and retroperitoneal drainage) were performed most frequently, and one third of the patients who underwent drainage procedures needed reoperation. Although debridement of the necrotic tissue (necrosectomy or resection of the pancreas) was performed in 33.3%, the mortality rate was 35.3%. There was no difference in the mortality rate between early and delayed operation. Recently two new modalities have been advocated for the management of severe acute pancreatitis in Japan. One is continuous regional arterial infusion of protease inhibitor and antibiotics, and the other is continuous hemodiafiltration. Further work is needed to establish the most effective procedures for the management of acute necrotizing pancreatitis and debridement of pancreatic infection.

Adolescent↗

PubMed1998

Genomic analysis of DUSP6, a dual specificity MAP kinase phosphatase, in pancreatic cancer.

DUSP6 (alias PYST1), one of the dual-specificity tyrosine phosphatases, is localized on 12q21, one of the regions of frequent allelic loss in pancreatic cancer. This gene is composed of three exons, and two forms of alternatively spliced transcripts are ubiquitously expressed. Although no mutations were observed in 26 pancreatic cancer cell lines, reduced expressions of the full-length transcripts were observed in some cell lines, which may suggest some role for DUSP6 in pancreatic carcinogenesis.

Blotting, Southern↗

PubMed1997

Frequent gain of copy number on the long arm of chromosome 20 in human pancreatic adenocarcinoma.

We have used comparative genomic hybridization (CGH) to survey genomic regions with aberrant copy numbers of DNA sequences in pancreatic adenocarcinoma. In 12 cell lines and 6 primary tumors from 18 patients with pancreatic adenocarcinomas, highly frequent losses (> 60%) were observed on chromosome arms 6q, 9p, and 18q and the Y chromosome. Moderately frequent losses (40-60%) were observed on chromosome arms 3p, 4q, 8p, and 21q. Interestingly, these samples showed extremely high frequencies of increases in copy numbers of DNA sequences on the long arm of chromosome 20 (15/18, 83%). We further analyzed five cell lines by fluorescence in situ hybridization (FISH) with probes on chromosome 20 to define the increase in copy number more accurately, and we found that 20q was increased to between 5 and 8 copies per cell. These results suggest the existence of an oncogene or oncogenes in 20q that play a role in the development and/or the progression of pancreatic carcinogenesis.

Adenocarcinoma↗