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Biomedical subjects

K Takenaka

Publications and source records attributed to K Takenaka.

At least 19 recordsLinked to original sources
PubMed1998

Activation of the protein kinase p38 in the spindle assembly checkpoint and mitotic arrest.

The mitogen-activated protein kinase (MAPK) superfamily comprises classical MAPK (also called ERK), c-Jun amino-terminal or stress-activated protein kinase (JNK or SAPK), and p38. Although MAPK is essential for meiotic processes in Xenopus oocytes and the spindle assembly checkpoint in Xenopus egg extracts, the role of members of the MAPK superfamily in M phase or the spindle assembly checkpoint during somatic cell cycles has not been elucidated. The kinase p38, but not MAPK or JNK, was activated in mammalian cultured cells when the cells were arrested in M phase by disruption of the spindle with nocodazole. Addition of activated recombinant p38 to Xenopus cell-free extracts caused arrest of the extracts in M phase, and injection of activated p38 into cleaving embryos induced mitotic arrest. Treatment of NIH 3T3 cells with a specific inhibitor of p38 suppressed activation of the checkpoint by nocodazole. Thus, p38 functions as a component of the spindle assembly checkpoint in somatic cell cycles.

3T3 Cells↗
PubMed1998

Ceramide formation leads to caspase-3 activation during hypoxic PC12 cell death. Inhibitory effects of Bcl-2 on ceramide formation and caspase-3 activation.

PC12 cells undergo apoptosis as well as necrosis following exposure to hypoxia. Following a 6-h hypoxic treatment, a time-dependent increase in intracellular ceramide level was observed with a concurrent decrease in sphingomyelin. It was also shown that the hypoxia-induced ceramide accumulation resulted from activation of neutral magnesium-dependent sphingomyelinase. Comparative kinetic analyses of the neutral sphingomyelinase in the cells under normoxia and hypoxia showed that hypoxia increased Vmax but did not affect Km of the enzyme. In PC12 cells overexpressing Bcl-2 which show strong resistance to hypoxia, sphingomyelin hydrolysis was decreased and activation of neutral sphingomyelinase was reduced. Addition of exogenous C2-ceramide induced cell death and activated caspase-3 as markedly as the hypoxia treatment. On the other hand, in PC12 cells overexpressing Bcl-2, significant decreases in cell death and inhibition of caspase-3 activation were observed after exogenous addition of C2-ceramide. The inhibitors of caspase-3 prevented cell death by either hypoxia or C2-ceramide. These results suggest that ceramide generated by activation of neutral magnesium-dependent sphingomyelinase mediates hypoxic cell death and that Bcl-2 has inhibitory effects on ceramide formation and caspase activation.

Animals↗
PubMed1998

A thoracoabdominal hepatectomy and a transdiaphragmatic hepatectomy for patients with cirrhosis and hepatocellular carcinoma.

OBJECTIVE: To evaluate the results of a thoracoabdominal hepatectomy and a transdiaphragmatic hepatectomy for hepatocellular carcinoma in patients with impaired liver function. DESIGN: Retrospective study. SETTING: A university hospital in Japan. PATIENTS: Twenty-seven patients who from 1991 to 1996 underwent a thoracoabdominal hepatectomy for hepatocellular carcinoma located mainly in the superior portion of the liver and 20 patients who underwent a transdiaphragmatic hepatectomy for hepatocellular carcinoma located near the diaphragm. MAIN OUTCOME MEASURES: Morbidity, survival, and disease-free survival after each operation. Comparisons were then made with 183 patients who had undergone an ordinary transabdominal hepatectomy during the same period. RESULTS: In the thoracoabdominal hepatectomy group, 17 patients underwent a partial resection, 4 patients underwent a subsegmentectomy, and another 6 patients underwent either a segmentectomy or a procedure that was greater in size than a segmentectomy, whereas all of the patients in the transdiaphragmatic group underwent a partial resection. The morbidities in the thoracoabdominal group included pleural effusion in 6 patients (22%); intra-abdominal infection in 5 patients (19%); and hepatic failure in 3 patients (11%), of whom 1 died (mortality rate, 4%). In the transdiaphragmatic group, only 2 patients (10%) had non-life-threatening complications. The cumulative survival rates and the disease-free survival rates of the patients at 3 years were 51% and 24% in the thoracoabdominal hepatectomy group and 62% and 30% in the transdiaphragmatic hepatectomy group; no significant differences were observed when these findings were compared with those of patients who had undergone a transabdominal hepatectomy. CONCLUSION: The outcomes of the patients undergoing thoracoabdominal hepatectomy and those undergoing a transdiaphragmatic hepatectomy were generally satisfactory in spite of the fact that these procedures were performed on patients with cirrhosis and impaired liver function.

Aged↗
PubMed1998

Ultrastructural study of development of hepatic necrosis induced by TNF-alpha and D-galactosamine.

Recent studies have suggested an association between tumor necrosis factor-alpha (TNF-alpha) and the development and progression of acute liver failure. To investigate the role of TNF-alpha in the mechanism of massive hepatic necrosis, we studied a mouse model of TNF-alpha and D-galactosamine (GalN) -induced hepatic necrosis by ultrastructural analysis. Administration of GalN caused edema of hepatocellular microvilli and widening of sinusoidal endothelial fenestrae (SEF); administration of TNF-alpha caused only a widening of the SEF. Massive hepatic necrosis with hemorrhage was seen 6 hr after concomitant administration of TNF-alpha and GalN. In the ultrastructural analysis, edema of the hepatocellular microvilli, widening of the SEF, and transmigration of red blood cells (RBC) and platelets to the space of Disse without exfoliation and necrosis of the sinusoidal endothelial cells were observed. Fibrin deposits were seen in areas adjacent to injured hepatocytes. The diameter of the SEF was significantly greater than in the nontreated group and the groups treated with TNF-alpha or GalN alone. These results suggest that as a consequence of the increase in diameter of the SEF, transmigration of RBCs and platelets to the space of Disse may have resulted in massive hepatic necrosis due to occlusion of the microcirculation.

Animals↗
PubMed1998

Early viral complications following CD34-selected autologous peripheral blood stem cell transplantation for non-Hodgkin's lymphoma.

A patient with non-Hodgkin's lymphoma who received a CD34-selected autologous peripheral blood stem cell transplant (PBSCT) developed cytomegalovirus retinitis, adenovirus-associated haemorrhagic cystitis (HC) and fatal herpes simplex virus pneumonia. Depletion of mature T cells from the graft and a persistent decrease in CD4+ lymphocytes following PBSCT may have predisposed this patient to such viral infections. Infusion of cryopreserved autologous PBSC (containing mature T cells) was effective for adenovirus-associated HC. Immunosuppression and resultant viral infections may affect patients receiving CD34-selected autologous transplantation.

Adenoviridae Infections↗
PubMed1998

Risk factors linked to postoperative morbidity in patients with hepatocellular carcinoma.

BACKGROUND: The aim of this study was to clarify the risk factors for morbidity as well as to establish an optimum surgical strategy for hepatocellular carcinoma (HCC). METHODS: The risk factors linked to postoperative complications were analysed in 388 patients over a 10-year period, according to the kind of operative procedure. RESULTS: Stepwise regression analysis revealed that the most important factors related to postoperative morbidity were: age, creatinine level and the histological grade of fibrosis for the bisegmentectomy; the presence of diabetes mellitus, blood urea nitrogen level, the indocyanine green dye retention rate at 15 min and blood loss for the segmentectomy; the presence of diabetes mellitus and blood loss for subsegmentectomy; the presence of diabetes mellitus, the aspartate aminotransferase level, and the total operating time for resection less than subsegmentectomy. CONCLUSION: The most important risk factors were not always related to liver function tests, but instead to other coexisting conditions such as diabetes mellitus and operation stress including operating time and blood loss. Therefore, any future treatment strategy of hepatic resection for HCC should make every effort both to evaluate coexisting conditions carefully and to reduce operative stress as far as possible.

Age Factors↗
PubMed1998

Prognostic factors after repeat hepatectomy for recurrent hepatocellular carcinoma.

OBJECTIVE: The aims of this study were to identify prognostic factors in patients who developed recurrent hepatocellular carcinoma (HCC) after repeat hepatectomy and to elucidate the role of multicentric occurrence in the second tumor after a first hepatectomy. SUMMARY BACKGROUND DATA: A repeat hepatectomy for recurrent HCC has been established as the most effective treatment modality, whenever it is possible. However, the prognostic factors for recurrent HCC after repeat hepatectomy have yet to be clarified. METHODS: Forty-one patients who underwent a curative repeat hepatectomy were retrospectively studied. Patient survival and disease-free survival after recurrence were univariately and multivariately analyzed using 38 clinicopathologic variables. The histologic grade of HCC at repeat hepatectomy was also compared with that at first hepatectomy. RESULTS: Patient survival after repeat hepatectomy did not differ substantially from that in 312 patients undergoing primary hepatectomy. However, the disease-free survival after repeat hepatectomy was significantly lower than that in patients with only a primary hepatectomy (p < 0.05). Multivariate analysis revealed only portal vein invasion in the first hepatectomy to be an independent and significantly poor prognostic factor. Regarding multicentric occurrence at repeat hepatectomy, only 6 of 40 patients (15%) whose specimens could be evaluated histologically were determined to be Edmondson and Steiner's Grade 1. CONCLUSIONS: The only prognostic factor identified in patients with recurrent HCC after repeat hepatectomy was portal vein invasion in the first hepatectomy. Most second tumors after the first hepatectomy are considered to be caused by metastatic recurrence, not by multicentric occurrence.

Algorithms↗
PubMed1997

Adenosquamous carcinoma of the liver: clinicopathologic characteristics and cytokeratin profile.

BACKGROUND: The clinicopathologic characteristics, biologic behavior, and histogenesis of primary adenosquamous carcinoma (ASC) of the liver have yet to be fully clarified. METHODS: Eight cases of ASC of the liver were analyzed both clinicopathologically and immunohistochemically using antibodies of cytokeratin (CK) 7, CK 8, CK 18, CK 19, and CK 903 (CK 5, CK 10, CK 11, and CK 14). The survival curve of the 6 patients with surgically resected ASC was compared with that of the 32 patients with common cholangiocarcinoma (CC). RESULTS: Most ASCs had invasive pathologic features, including venous invasion, lymphatic permeation, and intrahepatic metastases. There were lymph node metastases from 7 tumors (88%), and most of the metastases were adenocarcinoma. All adenocarcinoma (AC) components were positive for both CK 7 and CK 19. The squamous cell carcinoma (SCC) components were positive for CK 7 in all cases but were positive for CK 19 in only 5 cases (62.5%). The ACs were positive for CK 903 in only 3 cases (37.5%), whereas all SCCs were positive for CK 903. Almost all ACs were positive for both CK 8 and CK 18, whereas the SCCs were positive for CK 8 in only 3 cases (37.5%) and for CK 18 in no cases. All 6 patients with surgically resected ASC died of the disease within 1 year postoperatively. Their survival curve was significantly worse than that of the 32 patients with common CC (P < 0.001). The two patients on whom autopsy was performed also died within 1 year after diagnosis. CONCLUSIONS: ASC tended to have more aggressive biologic behavior and a poorer prognosis than common CC. The authors' immunohistochemical analysis of CK expression indicated that most of the ASCs of the liver that were studied developed from a squamous transformation of the preexisting CC.

Aged↗
PubMed1997

MAP kinase is required for the spindle assembly checkpoint but is dispensable for the normal M phase entry and exit in Xenopus egg cell cycle extracts.

In Xenopus laevis egg cell cycle extracts that mimic early embryonic cell cycles, activation of MAP kinase and MAP kinase kinase occurs in M phase, slightly behind that of maturation promoting factor. To examine the possible role of MAP kinase in the in vitro cell cycle, we depleted the extracts of MAP kinase by using anti-Xenopus MAP kinase antibody. Like in the mock-treated extracts, the periodic activation and deactivation of MPF occurred normally in the MAP kinase-depleted extracts, suggesting that MAP kinase is dispensable for the normal M phase entry and exit in vitro. It has recently been reported that microtubule depolymerization by nocodazole treatment can block exit from mitosis in the extracts if enough sperm nuclei are present, and that the addition of MAP kinase-specific phosphatase MKP-1 overcomes this spindle assembly checkpoint, suggesting the involvement of MAP kinase in the checkpoint signal transduction. We show here that the spindle assembly checkpoint mechanism cannot operate in the MAP kinase-depleted extracts. But, adding recombinant Xenopus MAP kinase to the MAP kinase-depleted extracts restored the spindle assembly checkpoint. These results indicate unambiguously that classical MAP kinase is required for the spindle assembly checkpoint in the cell cycle extracts. In addition, we show that strong activation of MAP kinase by the addition of a constitutively active MAP kinase kinase kinase in the absence of sperm nuclei and nocodazole, induced mitotic arrest in the extracts. Therefore, activation of MAP kinase alone is sufficient for inducing the mitotic arrest in vitro.

Animals↗
PubMed1997

Indications for palliative reduction surgery in advanced hepatocellular carcinoma. The use of a remnant tumor index.

OBJECTIVES: To clarify the indications for and the significance of palliative reduction surgery in the multidisciplinary treatment of advanced hepatocellular carcinoma (HCC) and to propose the use of a remnant tumor index (RTI) as a simplified criterion for palliative reduction surgery in cases of advanced HCC. DESIGN: A comparison of survival based on the RTI. SETTING: A large university hospital in Japan. PATIENTS: Twenty-five patients with advanced HCC who underwent palliative reduction surgery were divided into 3 groups as follows: group 1 (n = 9), the remnant tumor after operation existed only in the liver and the RTI was less than 5.0; group 2 (n = 11), the remnant tumor after operation existed only in the liver and the RTI was greater than 5.0; and group 3 (n = 5), extrahepatic metastatic tumor existed after operation. MAIN OUTCOME MEASURES: Pathological findings and survival rate after surgery. RESULTS: There was no significant difference in the degree of macroscopic intrahepatic metastases among the 3 groups; however, both the portal vein invasion and the histological grade tended to be more severe in groups 2 and 3. The respective 1-year and 3-year survival rates for group 1 were 67% and 33%, and those for group 2 were 21% and 0%. There were no survivors in group 3 at 1 year after surgery. Significant differences were found in the survival rates between groups 1 and 2 (P < .05), and between groups 1 and 3 (P < .05). CONCLUSION: Palliative reduction surgery for advanced HCC is only considered effective for patients with both an RTI of less than 5.0 and no extrahepatic metastasis.

Aged↗
PubMed1997

Significance of alpha-fetoprotein levels for detection of early recurrence of hepatocellular carcinoma after hepatic resection.

BACKGROUND: The recurrence of hepatocellular carcinoma (HCC) after surgery is common. The present study was conducted in order to clarify the significance of alpha-fetoprotein (AFP) in the detection of the early recurrence of HCC after surgery. METHODS: Fifty-eight patients who underwent a curative hepatic resection for HCC and whose preoperative AFP levels were >100 ng/ml, were selected for this study. RESULTS: In 26 cases, the postoperative AFP levels within 3 months after surgery did not decrease to <20 ng/ml (high AFP group). In the other 32 cases, the postoperative AFP levels within 3 months after surgery decreased to <20 ng/ml (low AFP group). No significant difference was observed in clinical or pathological backgrounds. The postoperative disease free rate in the low and high AFP groups was 84.2% and 18.4%, at 1 year, 61.2 and 4.6% at 3 years, respectively. The difference was statistically significant (P < 0.01). At the time of recurrence, the AFP levels increased in 25 (96.2%) of the patients who had early recurrence within 1 year after surgery as well as in 11 of 14 (78.5%) who had recurrence >1 year after surgery. The interval from surgery to recurrence significantly correlated with the doubling time of AFP at the time of recurrence in patients with early recurrence (within 1 year after hepatectomy) (r = 0.60, P < 0.01). In cases in which the preoperative AFP level was >100 ng/ml and the postoperative AFP level did not decrease to <20 ng/ml, early recurrence within 1 year after surgery would thus be strongly suspected. CONCLUSION: The measurement of the AFP levels after surgery is therefore considered to be important in the follow-up of hepatectomized patients, especially regarding the detection of early recurrence.

Aged↗
PubMed1997

The relationship between moyamoya disease and bacterial infection.

To examine the relationship between Moyamoya disease and bacterial infections, authors studied the serum of 85 cases of Moyamoya disease and the influence of Propionibacterium acnes (P. acnes) infection on intracranial arteries in rats. The serum levels of P. acnes antibody, IgM, transferrin (Tf), alpha 2-macroglobulin (alpha 2M) were significantly higher in Moyamoya disease than in normal volunteers. Moyamoya-like changes of the intracranial internal carotid arteries were histopathologically demonstrated in P. acnes infectious rats. These findings suggest that P. acnes and immunological factors might play a role in the pathogenesis of Moyamoya disease.

Adolescent↗
PubMed1997

Renal depressor mechanisms of physical training in patients with essential hypertension.

To clarify characteristics of the patients in whom exercise training lowers blood pressure and to elucidate the mechanisms by which exercise training lowers blood pressure, we evaluated 24-h blood pressure, glomerular filtration rate (GFR), renal blood flow (RBF), filtration fraction (FF), plasma renin activity (PRA), plasma aldosterone concentration (PAC), plasma norepinephrine concentration (PNE), and incremental area of insulin/glucose (sigmaI/sigmaG) during 75 g oral glucose tolerance test, and assessed arterial baroreceptor function (BSI) before and after a 3-week exercise training program (four 6-min sessions daily at 75% VO2 max). Patients were classified as responders (n = 15) if they showed statistically significant reduction in the multiple comparison of 24-h mean arterial pressure (MAP), or as nonresponders (n = 15) if they did not. Although there were no significant differences between responders and nonresponders in age, weight, MAP, GFR, RBF, RPF, FF, PNE, sigmaI/sigmaG, or BSI before exercise, renal vascular resistance (RVR; P < .05), PRA (P < .05), and PAC (P < .05) were significantly higher in responders than in nonresponders. The fractional excretion of sodium (FENa) (P < .05) were significantly lower in responders than in nonresponders. After exercise training, FF (P < .01), RVR (P < .05), PNE (P < .05) PRA (P < .01), and sigmaI/sigmaG (P < .05) decreased significantly only in responders. The decrease in MAP significantly correlated with the reductions in FF (r = 0.46, P < .05), PNE (r = 0.52, P < .01) and RVR (r = 0.40, P < .05). Thus, in patients who have higher RVR and PRA, exercise training lowered blood pressure in parallel to a reduction in RVR associated with decreases in sympathetic tone and improvement of insulin resistance. Our results suggest that exercise-induced changes in renal hemodynamics may contribute to the reduction in blood pressure in these patients.

Adult↗
PubMed1997

Increased incidence of cytomegalovirus (CMV) infection and CMV-associated disease after allogeneic bone marrow transplantation from unrelated donors. The Fukuoka Bone Marrow Transplantation Group.

Cytomegalovirus (CMV) infection and CMV-associated disease were monitored using the CMV antigenemia assay in 72 patients who received allogeneic bone marrow transplantation (BMT), and their incidences were compared between related and unrelated donor transplant patients. The incidence of CMV infection after BMT was significantly higher in patients who received transplants from HLA-matched unrelated donors than from HLA-matched sibling donors (87% vs 53%, P < 0.05). CMV-associated disease developed in 73% of unrelated and in 14% of sibling donor transplant patients (P < 0.01). The peak levels of CMV antigenemia were significantly higher in unrelated donors than in sibling donor transplant patients (16 vs 1 CMV antigen-positive cells per 50000 WBCs, P < 0.01). The median number of CMV antigen-positive cells on first detection was also significantly higher in unrelated donor transplant patients (15 vs 1, P < 0.01). The detection of CMV antigen-positive cells preceded the development of CMV-associated disease in 18% of unrelated donor transplant patients, suggesting a lower predictive value of CMV antigenemia for subsequent CMV-associated disease in unrelated donor BMT. Careful monitoring and further studies are needed for the early diagnosis and prevention of CMV-associated disease in unrelated donor BMT.

Adolescent↗
PubMed1997

Autologous peripheral blood stem cell transplantation for acute myelogenous leukemia.

The safety and efficacy of myeloablative therapy followed by autologous peripheral blood stem cell transplantation (ABSCT) for acute myelogenous leukemia (AML) were evaluated in 60 patients. Peripheral blood stem cells (PBSC) were collected during recovery after consolidation chemotherapy. High-dose chemotherapy consisting of busulfan (16 mg/kg), etoposide (40 mg/kg), and cytosine arabinoside (3 g/m2 x 4) (BEA regimen) was used for pretransplant conditioning in 13 patients. For the remaining 47 patients, granulocyte colony-stimulating factor (G-CSF) was administered concurrently with the BEA regimen during conditioning. Unpurged, cryopreserved PBSC containing a median number of 5.4 x 10(8) MNC/kg or 12 x 10(4) CFU-GM/kg were reinfused at transplantation. The median number of days to granulocytes exceeding 500/microl and last platelet transfusion were 15 (8-44) and 24 (0->180), respectively. The 3-year probabilities of disease-free survival (DFS) and relapse were 78.6 and 21.4% for patients transplanted in first remission, 29.6 and 64.4% for those in second or third remission, and 11.1 and 77.8% for those in relapse, respectively. There were no transplant-related deaths within 100 days of transplantation. Age, disease status at transplantation, and number of induction chemotherapies to first complete remission were risk factors affecting the outcome of ABSCT. These results of ABSCT for AML in first remission warrant a prospective study of ABSCT as post-remission therapy.

Acute Disease↗
PubMed1997

Long-term outcome of endoscopic balloon dilation in obstructive gastroduodenal Crohn's disease.

BACKGROUND AND STUDY AIMS: Although balloon dilation is widely used in nonmalignant pyloric stenosis, little information is available on either the short-term or long-term results of this type of therapy in patients with obstructive gastroduodenal Crohn's disease. PATIENTS AND METHODS: Five patients with Crohn's disease who had obstructive gastroduodenal lesions were treated using endoscopic balloon dilation. RESULTS: All the initial dilations successfully provided symptomatic relief. However, three of the five patients developed recurrent obstructive symptoms during a mean follow-up period of 4.2 years. Due to symptomatic recurrence, three patients required successive or regularly scheduled repeat balloon dilations, which were successful without any complications, and all of the patients were able to avoid surgical intervention. CONCLUSIONS: These results suggest that over a prolonged period of time, patients who have undergone balloon dilation for obstructive gastroduodenal Crohn's disease have a high rate of recurrence of symptomatic gastric obstruction. However, repeat dilations are successful in continuing to prevent the need for surgery.

Adult↗
PubMed1997

Purification of a factor from CSF in patient after SAH which induces the cytosolic free calcium elevation in vascular smooth muscle cells.

Cerebrospinal fluid from patients with aneurysmal subarachnoid hemorrhage induces the elevation of cytosolic free calcium [Ca2+]i in cultured vascular smooth muscle cells. We have purified a [Ca2+]i elevating factor from cerebrospinal fluid of a patient with subarachnoid hemorrhage due to aneurysm rupture. The calcium-elevating protein factor was purified to homogeneity by ammonium sulfate precipitation and a combination of Mono Q, Superose 12, and Mono S columns using liquid chromatography. Fifteen microgram of the purified protein was obtained from 340 mg of cerebrospinal fluid proteins and the molecular mass of the protein was estimated to be 81 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. It was also shown that the purified protein was cross-reactive with anti-human transferrin antibody. These results suggested that transferrin may be involved with the cerebral vasospasm after subarachnoid hemorrhage.

Animals↗