Search PubMed⌕ Search

Biomedical subjects

M Shimada

Publications and source records attributed to M Shimada.

At least 163 records · Page 9Linked to original sources
PubMed2000

Isolation and characterization of a serine protease from the sprouts of Pleioblastus hindsii Nakai.

An endopeptidase has been purified from sprouts of bamboo (Pleioblastus hindsii Nakai) to electrophoretic homogeneity by four purification steps. Its Mr was estimated to be 82 kDa by SDS-PAGE. Enzyme activity was inhibited strongly by diisopropyl fluorophosphate, and weakly by p-chloromercuriphenylsulfonic acid, but not at all by EDTA or pepstatin, indicating that it was a serine protease. The preferential cleavage sites for this protease were found to be large hydrophobic and amide residues at the P1 position. The specificity of the bamboo serine protease differed from that of cucumisin [EC 3.4.21.25], which cleaved the charged amino acid residues at the P1 position.

Amino Acid Sequence↗
PubMed2000

Cleavage specificity of cucumisin, a serine protease, with synthetic substrates.

The substrate specificity of a plant serine protease, cucumisin (EC 3.4.21.25), was studied by the use of synthetic oligopeptides and peptidyl-pNA substrates. Since P1'-Ser, Ala, and Gly substrates were hydrolyzed rapidly, cucumisin appears to prefer a small side chain at the P1' position of the oligopeptide substrate. The k(cat)/Km for the hydrolysis of P1-Leu, Ala, Phe, and Glu substrates demonstrated that they were preferentially cleaved over P1-Lys, diaminopropionic acid (Dap), Gly, Val, and Pro substrates. From the digestion of peptidyl-pNAs, the specificity of the protease was determined to be broad, but the preferential cleavage sites were hydrophobic amino acid residues at the P1 position.

Cucurbitaceae↗
PubMed2000

Cucumisin-like protease from the latex of Euphorbia supina.

A protease has been purified from the latex of Euphorbia supina Rafin by two steps of chromatography. The Mr was estimated by SDS-PAGE to be 80 kDa. Its activity was inhibited strongly by diisopropyl fluorophosphate, but not by EDTA, pepstatin, or cysteine protease inhibitors, indicating that the enzyme is a serine protease. The specificity of the protease is broad, but the preferential cleavage sites were C-terminal sites of hydrophobic amino acid residues. The N-terminal sequence of the first fifteen residues was determined and six of the residues match those in cucumisin [EC 3.4.21.25], a protease from the sarcocarp of melon fruit (Cucumis melo L. var. Prince). The results indicate that the E. supina protease is a cucumisin-like serine protease.

Amino Acid Sequence↗
PubMed2000

Effects of wortmannin on the kinetics of GVBD and the activities of the maturation-promoting factor and mitogen-activated protein kinase during bovine oocyte maturation in vitro.

The present study was conducted with the objective of examining the effect of wortmanin, a specific PI 3-kinase inhibitor, on the kinetic of GVBD, and on the activities of the maturation-promoting factor (MPF) and mitogen-activated protein (MAP) kinase during bovine oocyte maturation. The time sequence for GVBD was not different between oocytes cultured with or without wortmannin. Most of the cultured oocytes were at the filamentous bivalents stage after 4 h of culture. Six hours after the start of culture, most of the oocytes possessed germinal vesicles with condensed bivalent, and by 10 h of culture nearly all of the cultured oocytes underwent GVBD. A gradual increase in MPF activity until 12 h of culture was observed in the presence and absence of wortmannin. A sharp decrease in MPF activity in oocytes cultured without wortmannin treatment was recorded at 14 h of culture. Thereafter, MPF regained activity, reaching a maximum level at 20 to 24 h of culture. For oocytes cultured with wortmannin, no decline in the activity of MPF was observed during the interval from 12 to 24 h of culture. For these oocytes the MPF activity remained nearly stable during this transition until the end of incubation. The presence of wortmannin in the maturation medium did not alter MAP kinase activity. Taken together, these observations indicate that inhibition of PI 3-kinase does not modulate the time sequence of GVBD or the pattern of MAP kinase activity in bovine oocytes. However, PI 3-kinase might be one of the molecules that regulate the sharp reduction in the activity of MPF during the MI/MII transition.

Androstadienes↗
PubMed2000

Zonisamide treatment of early infantile epileptic encephalopathy.

A case of early infantile epileptic encephalopathy with suppression-bursts (EIEE or Ohtahara syndrome) with an excellent response to zonisamide is reported. Tonic spasms began immediately after birth and increased in number, such that they formed a series of several dozen spasms lasting for 5 to 15 minutes. When the patient was 1 month old, a partial clonic seizure emerged predominantly on the right side of her face and extremities. It was often followed by tonic spasms and later continued after the beginning of the spasm series. Interictal electroencephalography demonstrated an atypical suppression-burst pattern and focal paroxysmal discharges. Detailed hematologic tests, magnetic resonance imaging, single-photon emission computed tomography, and auditory brainstem response did not reveal any metabolic or structural abnormalities. Oral administration of zonisamide first controlled the partial seizures and, subsequently, the tonic spasms in a dose-dependent fashion. The mode of response to zonisamide and the findings on electroencephalography indicate that EIEE may be caused by multiple independent brain lesions and that EIEE is a heterogeneous disorder. It is suggested that zonisamide may be useful in the treatment of EIEE.

Anticonvulsants↗
PubMed2000

Changes in diffusion-weighted MRI after status epilepticus.

A 3-year-old male developed hemiplegia and aphasia after convulsive status epilepticus. Diffusion-weighted magnetic resonance images demonstrated cytotoxic edema in the white matter 6 days after the seizure episode and subsequently in the gray matter after an additional 7 days. Diffusion-weighted magnetic resonance images demonstrated a subacute evolution of the pathologic process after the status epilepticus.

Brain Edema↗
PubMed2000

Mechanism of the combination effect of wild-type TP53 gene transfection and cisplatin treatment for ovarian cancer xenografts.

To clarify the effect of a combination treatment consisting of a recombinant adenovirus carrying a wild-type TP53 gene (AxCATP53) and cisplatin (CDDP), we examined p53-dependent apoptosis in ovarian cancer xenografts with and without the wild-type TP53 gene. Severe combined immunodeficiency (SCID) mice were implanted with ovarian cancer cell lines consisting of SK-OV-3 cells without the TP53 gene and KF cells with the TP53 gene. In SK-OV-3 and KF tumours, the inhibitory effect of the combination treatment on tumour growth was significant, compared with a single treatment with CDDP alone or AxCATP53 alone. The apoptotic index increased significantly after combination treatment in the SK-OV-3 tumours. The expression of Bax protein in SK-OV-3 tumours was weak, but strengthened after TP53 gene transfection. In contrast, AxCATP53 transfection did not affect CDDP-induced apoptosis in the KF tumours. Therefore, combination treatment of AxCATP53 and CDDP may be a new strategy for treating ovarian cancer with or without the TP53 gene.

Animals↗
PubMed2000

Sensitivity to paclitaxel is not related to p53-dependent apoptosis in ovarian cancer cells.

We conducted this study to determine whether the sensitivity of ovarian cancer cells to paclitaxel (PTX) relates to cells undergoing p53-dependent apoptosis. Human ovarian adenocarcinoma cell lines (SK-OV-3, KF and KP cells) were used in this study. In SK-OV-3 and KP cells, which have a homozygous deletion of the TP53 gene, wild-type TP53 gene-transduction markedly enhanced the sensitivity to cisplatin (CDDP), but did not enhance the sensitivity to PTX. In all cells, the apoptotic index was increased by CDDP or PTX. After exposure to CDDP, p53 and Bax protein expression increased and Bcl-xL expression decreased in the KF cells and TP53 gene-transducted SK-OV-3 cells. However, these proteins did not change in KP cells. Therefore, the role of p53 in CDDP-induced apoptosis depends upon the cell type. In contrast, TP53 gene status did not correlate with PTX-induced cytotoxicity in any of the cell lines with differing apoptotic pathways. In conclusion, the sensitivity to PTX may not be related to p53-dependent apoptosis in ovarian cancer cells.

Antineoplastic Agents↗
PubMed2000

The importance of hepatic resection for hepatocellular carcinoma originating from nonfibrotic liver.

BACKGROUND: Our study aimed to clarify the characteristics of hepatocellular carcinoma (HCC) in patients with a nonfibrotic liver and the role of surgical resection for HCC in nonfibrotic liver compared with patients with HCC in fibrotic or cirrhotic livers. STUDY DESIGN: A total of 516 patients who underwent hepatectomy between April 1985 and June 1999 were classified into two groups: a nonfibrotic liver group (n=65) and a fibrotic liver group (n=451), which included fibrotic or cirrhotic livers. Clinicopathologic variables were then compared between the groups, including disease-free survival rate and patient survival rate. RESULTS: Only 8 of 65 patients (12.3%) with a nonfibrotic liver showed a histologically completely normal liver. The numbers of men and patients with alcohol abuse in the nonfibrotic liver group were higher than in the fibrotic liver group. The numbers of patients with positive hepatitis B antigen and positive hepatitis C antibody in the nonfibrotic liver group were lower than in the fibrotic liver group. Results of liver function tests in the nonfibrotic liver group were better than those in the fibrotic liver group. The rates of both portal vein and hepatic vein invasion of cancer cells in the nonfibrotic liver group were higher than in the fibrotic liver group. The tumor size in the nonfibrotic liver group was larger than in the fibrotic liver group. The patient survival and disease-free survival rates in the nonfibrotic liver group were better than in the fibrotic liver group. CONCLUSIONS: Hepatic resection can be beneficial for patients with HCC originating from a nonfibrotic liver when compared with fibrotic or cirrhotic patients with HCC.

Carcinoma, Hepatocellular↗
PubMed2000

Clinicopathologic features and postoperative prognosis of multicentric small hepatocellular carcinoma.

BACKGROUND: Assessment of clinicopathologic characteristics and postoperative prognoses for patients with multicentric hepatocellular carcinoma (HCC) is important to determine not only a need to operate, but also an appropriate treatment after hepatic resection. STUDY DESIGN: Between May 1990 and April 1998, among 116 patients with an initial hepatectomy for HCC measuring 3 cm or less in maximum diameter, 34 patients had multicentric HCC (MC group), and 82 patients had single nodular HCC (SN group). To clarify the clinicopathologic features of patients in the MC group versus the SN group, we compared both the clinicopathologic parameters and the postoperative prognosis after curative hepatectomy between the two groups. RESULTS: The percentages of patients positive for hepatitis B surface antigen and hepatitis C virus antibody were not significantly different between the two groups. No differences were noted in pathologic characteristics of the main tumor or tumor markers. On the other hand, in the MC group, the percentage of patients evaluated in a Child's classification as either B or C was significantly higher (p < 0.05) than that of patients in the SN group, indicating that patients with multicentric HCC have a poor hepatic functional reserve. Both survival and disease-free survival of patients in the MC group who underwent a curative hepatectomy did not differ statistically from those in the SN group. CONCLUSIONS: Our results indicate that hepatic resection is useful, even for patients with multicentric HCC, if a curative hepatectomy can be performed and liver function can be saved, despite their poor hepatic functional reserve.

Aged↗
PubMed2000

Human serum induces apoptosis of xenogenic cardiomyocytes in vivo and in vitro.

Discordant xenotransplantation is complicated by delayed xenograft rejection (DXR). Previous studies have demonstrated that anti-apoptotic genes are protective against DXR. This study examines the hypothesis that apoptosis plays a role in human anti-xenograft responses. C57BL/6 mice and NOD SCID mice were given a single intravenous injection of either a lethal dose (LD, survival < 30 min) or a sublethal dose (SLD) of human serum, and isolated pig and mouse rod-shaped cardiomyocytes were exposed to human serum in vitro. In situ detection of apoptotic cells in mouse hearts was assessed using a terminal deoxynucleotidyl transferase-mediated dUTP nicked-end labeling assay. Mice transfused with human serum had approximately a 10-fold increased percentage of apoptotic cells after SLD 18 h post-injection compared with animals given saline, and a fourfold increase over LD. Administration of cobra venom factor (CVF) decomplemented SLD 18 h did not significantly (P > 0.05) alter the percentage apoptosis. The addition of 20 mM Gal-alpha-1,3-Gal to SLD 18 h significantly (P < 0.05) reduced percentage apoptosis to levels comparable to saline treated control animals. In vitro using mouse and pig cardiomyocytes demonstrated parallel results as in vivo experiments. Human serum induces apoptosis of cardiomyocytes in immunocompetent and immunoincompetent mice in vivo, as well as mouse and pig cardiomyocytes in vitro. Further, this apoptotic response can be inhibited by the addition of Gal-alpha-1,3-Gal without affecting the capacity of the serum to cause HAR. These results demonstrate that a putative human serum factor induces a delayed apoptotic injury of xenograft tissues, and supports the hypothesis that apoptosis may be an important mediator of DXR.

Animals↗
PubMed2000

Expressional patterns of cytokines in a murine model of acute myocarditis: early expression of cardiotrophin-1.

To determine the role of cytokines in acute myocarditis, we examined expressional patterns of cardiotrophin-1 (CT-1), TNF-alpha, and IL-1alpha in a murine model of acute myocarditis. Ten-day-old Institute of Cancer Research mice were injected with Coxsackievirus B3 and killed on Days 1, 2, 3, 4, 5, 7, 10, 14, and 28 of injection. TNF-alpha and IL-1alpha expressions were investigated on histological sections from each heart, and mRNA expression of TNF-alpha, IL-1alpha, and CT-1 in the heart was examined by reverse transcription-polymerase chain reaction and RNase protection assay. To determine myocardial regeneration, cardiomyocytic DNA synthesis was investigated using bromodeoxyuridine on Days 3, 5, 7, and 10, and the labeling index was calculated in each heart. Age-matched uninfected mice were used as controls. TNFalpha and IL-1alpha expression was first detected in the cardiomyocytes on Day 3 and reached the maximum level on Day 7, when inflammatory changes were most prominent. Although an increased expression of TNFalpha and IL-1alpha mRNA was also detected on Day 3, CT-1 mRNA expression was distinctly augmented on Day 2. The labeling indices in the hearts with myocarditis were significantly higher than in those of the controls in all of the time points examined. CT-1 expression preceded TNF-alpha and IL-1alpha expressions and active DNA synthesis in a murine model of acute myocarditis. All CVB3-infected mice with anti-glycoprotein-130 antibody treatment died within 6 days. CT-1 may exert a protective role by modulating cytokine production and by inducing cardiomyocytic proliferation in CVB3-infected murine hearts.

Acute Disease↗
PubMed2000

Comparison between in vivo and in vitro chemokine production in Helicobacter pylori infection.

BACKGROUND: Enhanced gastric mucosal chemokine activity has been demonstrated in patients with Helicobacter pylori infection. However, little is known about the mechanisms involved in this phenomenon. AIM: To examine whether in vivo chemokine activity is similar to in vitro response of gastric epithelial cells infected by H. pylori. PATIENTS AND METHODS: Antral biopsy specimens were obtained from patients with H. pylori infection for organ culture, isolation of H. pylori and histological examination. RESULTS: In organ cultures of mucosal tissues, the levels of interleukin-8 and growth-related gene product a were elevated in patients with peptic ulcer disease compared with those with erosive gastritis or endoscopically normal mucosa. However, there were no significant differences in in vitro cultures of MKN45 or KATO III cells that were infected with H. pylori isolated from these same patients. These in vivo and in vitro alpha-chemokine levels showed no significant association with the presence of cagA gene and CagA protein, ureB genotype, or binding capacity to MKN45 or KATO III cells in individual H. pylori isolates. In contrast, in vivo mucosal alpha-chemokine activity correlated with H. pylori colonization density. CONCLUSION: Mucosal chemokine profiles and inflammatory responses in H. pylori infection may be associated more closely with host factors, including those determining bacterial adhesiveness, than with differences in H. pylori strains.

Antigens, Bacterial↗
PubMed2000

Clinical-pathological comparison of clinical prostate cancer between Japanese Americans in Hawaii and Japanese living in Japan.

In an attempt to determine the role of environmental factors in the etiology of prostate cancer, we compared the clinical-pathological findings of prostate cancer among Japanese Americans in Hawaii and Japanese living in Japan. Our study showed that prostate cancer in Japanese living in Japan is more advanced than in Japanese Americans. The findings indicate that screening for prostate cancer in Japan is far behind that in the USA. The difference in level of cancer screening also precluded our attempt to analyse environmental factors contributing to prostate cancer progression in the two groups. The variation in method of clinical detection of prostate cancer between the USA and Japan is also likely to contribute to the apparent difference in the incidence of the disease.

Aged↗
PubMed2000

Prospective evaluation of preoperative chemotherapy in resectable squamous cell carcinoma of the thoracic esophagus.

A prospective study was performed to clarify the surgical outcome of patients with esophageal carcinoma who would benefit from induction chemotherapy followed by surgery. Of 55 eligible patients, 42 (76.3%) agreed to randomization with either chemotherapy followed by surgery (n = 21) or surgery alone (n = 21). The other 13 refused. The chemotherapy consisted of cisplatin, 5-fluorouracil and leucovorin. All 55 patients underwent esophagectomy with two- or three-field resection, including two (3.6%) hospital mortalities. Of the 21 patients receiving chemotherapy, the response rate was 33.3% after the first course and 60% after the second course. A complete response was not obtained. Responders to the first course showed a prolonged survival, however time to treatment failure did not differ between patients treated with chemotherapy followed by surgery or surgery alone. This chemotherapy offered a worse surgical outcome for patients with pretreatment diagnosis of T3. Multivariate analysis identified a partial response to the first course of chemotherapy to be a favorable prognostic indicator. Preoperative chemotherapy does not give a survival benefit over surgery alone for patients with advanced tumor (T3). Initial response to the first dose of chemotherapy is deemed to be a prognostic factor for patients with less advanced tumor (T1/T2).

Aged↗