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Biomedical subjects

M Sakon

Publications and source records attributed to M Sakon.

At least 73 records · Page 4Linked to original sources
PubMed1999

Expression and prognostic roles of the G1-S modulators in hepatocellular carcinoma: p27 independently predicts the recurrence.

Expression of cell-cycle modulators at the G1-S boundary, retinoblastoma gene product (pRb), p21, p16, p27, p53, cyclin D1, and cyclin E was investigated with 104 hepatocellular carcinomas (HCC), as well as 90 of their adjacent noncancerous lesions and 9 normal liver control specimens. The labeling indices (LI) of pRb, p21, p16, and p27 were higher in HCC lesions than in the adjacent noncancerous lesions and normal controls. Especially, p27 LI in noncancerous lesions was significantly higher than that in normal livers (P =.011). Aberrant p53 expression and cyclin D1 and E overexpression were observed exclusively in HCC lesions. pRb was positive in 85.6% of the HCC cases and was not related to any clinicopathological parameters. The p21 LI was generally low (average, 5.5 +/- 9.8). Although a negative regulator, p21 LI was higher in cases with intrahepatic metastasis (P =.0359). The p16 LI was significantly decreased (P =.0121) in cases with advanced stage. p27 LI was significantly decreased in cases with portal invasion (P =.0409), poor differentiation (P <.0001), larger size (P =.0421), and intrahepatic metastasis (P =.0878, borderline significance). On the other hand, aberrant p53 expression showed positive relationships with poor differentiation (P =.0004) and Ki-67 LI (P =. 0047). Cyclin D1 overexpression was found in 32.6% of the cases and occurred more frequently in those with high Ki-67 LI (P =.0032), pRb expression (P =.0202), poor differentiation (P =.0612, borderline significance), and intrahepatic metastasis (P =.0675, borderline significance). Cyclin E was overexpressed in 35.5% and had positive relationships with Ki-67 LI (P =.0269) and stage (P =.0125). In univariate analysis, cases with p27 LI < 50 (P =.0004), cyclin D1 overexpression (P =.0041), and cyclin E overexpression (P =.0572, borderline significance) showed poorer outcomes for disease-free survival (DFS). In multivariate analysis, p27 expression could be recognized as an independent prognostic marker for DFS. These findings suggest that in HCC: 1) p27 is active against HCC progression in early phases and, possibly, hepatocarcinogenesis as a negative regulator and can be a novel prognostic marker for DFS; and 2) cyclin D1 predominantly works for cell-cycle progression at the G1-S boundary.

Adult↗
PubMed1999

Measurement of hepatocyte growth factor in serum and plasma.

To investigate whether serum or plasma should be used for the measurement of blood hepatocyte growth factor, the levels were compared in 28 normal subjects and 30 patients who had undergone surgery. The serum level was significantly higher than the plasma level. The serum and plasma hepatocyte growth factor levels differed markedly depending on the subjects, although overall there was a significant correlation between levels (r=0.862, P=0.0001). In serum obtained by the clotting of platelet- or leukocyte-containing plasma with thrombin, hepatocyte growth factor increased in proportion to the number of leukocytes. The difference between serum and plasma hepatocyte growth factor levels also correlated with the number of leukocytes in the patients (r=0.642, P=0.0004). Such a correlation was not observed for platelets. These findings suggest that the serum hepatocyte growth factor level does not strictly reflect the in vivo blood level, due to the release from leukocytes during sample preparation (i.e., blood clotting ) and that plasma is more suitable for assay of blood hepatocyte growth factor.

Blood Cell Count↗
PubMed1999

Gradients in cytoplasmic calcium concentration ([Ca2+]i) in migrating human umbilical vein endothelial cells (HUVECs) stimulated by shear-stress.

Using a parallel-plate flow-chamber and confocal laser scanning microscopy (CLSM), we studied the distribution and temporal changes in intracellular Ca2+ concentration ([Ca2+]i) in migrating HUVECs stimulated by shear-stress. In the presence or absence of ATP, shear-stress (10 dyne/cm2) caused morphological change and migration of individual HUVECs in the random direction. After 120 minute exposure to shear-stress, 70% of the cells migrated in the direction of flow, whereas, as many as 30% of the cells migrated to the upstream against flow. A nonspecific plasma membrane Ca2+ channel blocker, Ni2+, abolished such responses markedly, suggesting that Ca2+ influx may be essential for shear-stress dependent morphological change and migration of HUVECs. Analysis of [Ca2+]i distribution revealed the appearance of localized [Ca2+]i elevation inside lamellipodium formed in the direction of cell migration. The localized rise in [Ca2+]i might be closely related with morphological change to regulate the direction of cell migration induced by shear-stress.

Adenosine Triphosphate↗
PubMed1999

Evaluation of preoperative and intraoperative arterial stimulation and venous sampling for diagnosis and surgical resection of insulinoma.

BACKGROUND: The precise intraoperative localization of insulinoma is essential for successful surgical treatment. In addition to various imaging modalities developed recently, arterial stimulation and venous sampling (ASVS) has also been used for tumor localization. METHODS: Preoperative and intraoperative ASVS procedures were performed in 6 patients with insulinoma. Intraoperative ASVS was performed before and after tumor resection. Immunoreactive insulin (IRI) concentrations and the IRI ratio (IRI concentration at each time interval after calcium injection/baseline IRI concentration) were determined by the conventional or a quick IRI method. RESULTS: The site of the tumor was identified preoperatively in all patients. The peak of the IRI ratio varied widely, but setting the cutoff value at 3.0 clearly differentiated peak IRA ratios in feeding arteries from those of nonfeeding arteries. Intraoperative ASVS showed a similar elevation of IRI levels, but the elevation disappeared after tumor resection in all but 1 patient. In 2 patients, resection of the tumor was confirmed during surgery by measuring IRI levels by the quick IRI method. CONCLUSIONS: A combination of ASVS and conventional imaging modalities is useful for precise localization of insulinoma. Resection of the tumor can be confirmed intraoperatively by comparing IRI levels associated with preoperative and postresective ASVS.

Adult↗
PubMed1999

Evaluation of regional liver function by gadolinium-EOB-DTPA-enhanced MR imaging.

We evaluated the role of magnetic resonance (MR) imaging with gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA), in estimating regional liver function in a rat ischemia-reperfusion model. Ischemic liver damage was induced in the right lobe by vascular clamping for 0 (sham), 30 (I-30), 60 (I-60), and 90 min (I-90 group). The ischemic lobes in the I-60 and I-90 groups was clearly visualized as a high intensity area in the T1 images at late phase of Gd-EOB-DTPA enhancement, Moreover, the T1/2 of signal intensity in ischemic lobes significantly correlated with the duration of vascular clamping. We also observed significant correlation between T1/2 and ATP concentration in the liver tissue (r = -0.719, P = 0.04). Our results indicate that MR imaging with Gd-EOB-DTPA is useful for evaluation of regional liver function in rats.

Animals↗
PubMed1999

Both cell proliferation and apoptosis significantly predict shortened disease-free survival in hepatocellular carcinoma.

In this study, we investigated the proliferating cell index by the percentage of Ki-67 expressing cells (Ki-67 LI) and the apoptotic index (AI) by the number of morphologically apoptotic cells per 1000 carcinoma cells in haematoxylin and eosin sections of 76 hepatocellular carcinomas (HCC). Both indices showed excellent correlation with each other (P < 0.0001) and were significantly higher in cases of poor differentiation, of advanced stages, with portal invasion and with intrahepatic metastasis. Furthermore, cases with higher Ki-67 LI or higher AI displayed poor outcomes for disease-free survival (P = 0.0001 and P = 0.0005) by univariate analysis. By multivariate analysis, both indices could be regarded as independent prognostic factors. These results strongly suggest that Ki-67 LI and AI have very similar clinical significance, reflecting the existence of biologically aggressive phenotypes and poor disease-free survival rate in HCC.

Aged↗
PubMed1999

Overexpression of cyclooxygenase-2 in carcinoma of the pancreas.

The level of cyclooxygenase (COX)-2 has been investigated recently in various human carcinomas. In the present study, we examined the distribution and extent of COX-2 protein in human pancreatic tumors using immunohistochemistry. A strong expression of COX-2 protein was present in 23 of 52 (44%) pancreatic carcinomas, a moderate expression was present in 24 of 52 (46%) pancreatic carcinomas, and a weak expression was present in 5 of 52 (10%) pancreatic carcinomas. In contrast, benign tumors showed weak expression or no expression of COX-2, and only islet cells displayed COX-2 expression in normal pancreatic tissues. Overexpression of COX-2 in carcinoma tissues was also confirmed by Western blot analysis. Furthermore, consistent with the results at protein levels, reverse transcription-PCR analyses indicated that COX-2 mRNA was overexpressed in 7 of 13 (54%) carcinomas, but in none of 3 benign tumors. Our findings suggest that COX-2 inhibitors might be potentially effective against pancreatic carcinomas and that COX-2 may be involved in certain biological processes in pancreatic islets.

Adenocarcinoma↗
PubMed1999

[A case report of hepatocellular carcinoma with hepatic and portal venous tumor thrombus and multiple intrahepatic metastasis who survived over 1 year after the operation with combined locoregional chemotherapy].

Hepatocellular carcinoma (HCC) with vascular invasion and/or intrahepatic metastasis (IM) has a poor prognosis, so advanced HCC may be considered as a contraindication for hepatectomy. We experienced a case of HCC with hepatic venous and portal venous tumor thrombus and multiple IM who survived over 1 year after the operation with combined locoregional chemotherapy. (Case): A 67-year-old male patient was diagnosed with HCC with extracapsular invasion after transarterial embolization (TAE). CT scan revealed the HCC had a right portal venous tumor thrombus and multiple IM. Posterior lobectomy and thrombectomy of hepatic venous and portal venous tumor thrombus and placement of portal venous catheter ware performed. From the first day after operation the patient received continuous intravenous and intraportal 5-FU for 3 weeks. At the first month after operation, TAE and PEIT were given against residual IM. After discharge the patient received hepatic arterial infusion chemotherapy (MTX/CDDP/5-FU/Leucovorin). Fourteen months after operation, the patient is surviving in good physical condition.

Aged↗
PubMed1999

Molecular mechanism involved in increased expression of sialyl Lewis antigens in ductal carcinoma of the pancreas.

Increased expression of sialyl Lewis antigens, sLe(a) and sLe(x), is frequent during malignant transformation and tumor progression of gastrointestinal cancers and it is assumed to be correlated with the increased metastatic potential of tumor cells and, consequently, with poor patient survival. To determine the influence of the increased expression of these antigens in disease progression of ductal carcinoma of the pancreas, immunohistochemical expressions of sLe(x) and sLe(a) in 51 ductal carcinomas of the pancreas were examined. We also examined the expression of glycosyltransferase genes, which are involved in the synthetic pathways of these antigens to understand the molecular mechanism involved in the increased expression of these antigens. Of the 51 primary ductal carcinomas of the pancreas, 40 (78.4%) were sLe(a)-positive and 11 (21.6%) were sLe(a)-negative; 16 (31.4%) were sLe(x)-positive and 35 (68.6%) were sLe(x)-negative. Although there were no significant differences in any examined clinicopathological factors such as age, sex, histological type, tumor size, presence of lymph node metastasis, or presence of vessel invasion between the positive and negative groups with both the sLe(a) and sLe(x) antigens, patient survival tended to be worse in the antigens-positive group than in the antigens-negative group. Increased expression, however, was not dependent on the increased expression of a single glycosyltransferase gene examined among five such genes, which are postulated to be responsible for the synthesis of the sLe(a) and sLe(x) epitopes in the glycosylation pathway. Furthermore, the increased expression of these antigens was not closely associated with mutations status of the K-ras or p53 genes. These findings suggested that increased expression of sialyl Lewis antigens are involved in pancreatic tumorigenesis and that the accumulation of genetic alterations or epigenetic changes is responsible for the molecular mechanisms of increased expression of the sLe(a) and sLe(x) antigens in ductal carcinomas of pancreas.

Adenocarcinoma↗
PubMed1999

Increased expression of COX-2 in nontumor liver tissue is associated with shorter disease-free survival in patients with hepatocellular carcinoma.

Recent studies have shown increased levels of cyclooxygenase-2 (COX-2) in a variety of human malignancies including hepatocellular carcinoma (HCC), but little is known about the prognostic value of COX-2 in HCC or its associated nontumor liver tissue. We examined the expression of COX-2 protein by immunohistochemistry in 53 patients with HCCs whose corresponding nontumor tissues were hepatitis C virus-related chronic hepatitis (n = 21) and cirrhosis (n = 32). Samples of nine histologically normal livers and eight precancerous dysplasias were also analyzed. The level of COX-2 increased from normal liver to chronic hepatitis to cirrhosis. The majority of cirrhotic livers (81%) displayed marked COX-2 expression. In dysplasias, COX-2 expression was mainly moderate or strong (88%). In HCC, 17% of samples displayed a high COX-2 expression, and 37% of samples expressed COX-2 at a moderate level. Concordant results were obtained with reverse transcription-PCR and Western blot analyses. Clinicopathological survey indicated a significant correlation between COX-2 expression and differentiated carcinoma (P = 0.019). Although there was no correlation between COX-2 expression in HCC and prognosis, a striking difference was found between COX-2 expression in nontumor tissue and shorter disease-free survival (P = 0.0132). Moreover, high COX-2 expression in nontumor tissue was significantly correlated with the presence of active inflammation (P < 0.0001). The present findings suggest that COX-2 expression in nontumor tissue may play a positive role in relapse of HCC after surgery.

Blotting, Western↗
PubMed1998

Shear stress down-regulates gene transcription and production of adrenomedullin in human aortic endothelial cells.

Vascular endothelial cells are potent modulators of vascular tone in response to shear stress. Levels of vasoactive peptides such as adrenomedullin (AM), endothelin-1 (ET-1), C-type natriuretic peptide (CNP), and nitric oxide (NO) are affected by fluid shear stress. AM, a potent vasodilator and suppressor of smooth muscle cell proliferation, contains the shear stress responsive element (SSRE) "GAGACC" in its promoter region. To examine the role of AM in the shear stress response, cultured human aortic endothelial cells (HAoECs) were exposed to fluid shear stresses of 12 and 24 dynes/cm2 in a cone-plate shear stress loading apparatus for various time periods, and the levels of AM gene expression and peptide secretion from HAoECs were measured by Northern blotting analysis and radioimmunoassay (RIA), respectively. Both AM gene transcription and AM peptide levels were down-regulated by fluid shear stress in a time- and magnitude-dependent manner. Our results demonstrate that the normal level of arterial shear stress down-regulates AM expression in HAoECs, suggesting that AM participates in the modulation of vascular tone by fluid shear stress.

Adrenomedullin↗
PubMed1998

Plasma heparin-binding EGF-like growth factor levels in patients after partial hepatectomy as determined with an enzyme-linked immunosorbent assay.

We recently showed that heparin-binding EGF-like growth factor (HB-EGF) has hepatotrophic effects. In this study, we developed an ELISA system with high specificity and sensitivity for human plasma HB-EGF. In 14 patients who underwent partial hepatectomy, plasma HB-EGF levels were measured serially after surgery. In patients who underwent gross hepatectomy (lobectomy and segmentectomy), plasma HB-EGF levels increased, reaching maximal levels approximately 5 to 7 days after surgery. In patients who underwent minor hepatectomy (subsegmentectomy), plasma HB-EGF levels did not increase. Maximal plasma HB-EGF levels were significantly higher in patients who had a percent increased volume of the remaining liver (%ILV) above 20% than those who had a %ILV below 20% (32.4 +/- 19.6 pg/ml vs 7.4 +/- 2.7, P < 0.05). The plasma HB-EGF values did not correlate with WBC counts, C-reactive protein, or alanine aminotransferase. Plasma HB-EGF may be a marker for liver regeneration after hepatectomy in humans.

Aged↗
PubMed1998

Direct antigen presentation through binding of donor intercellular adhesion molecule-1 to recipient lymphocyte function-associated antigen-1 molecules in xenograft rejection.

Cellular interactions that lead to graft rejection were examined in a rat-to-mouse xenogeneic combination using species-specific monoclonal antibodies (mAbs) against donor and recipient intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1) molecules, respectively. Although both mAbs displayed moderate blocking activity in an in vitro mixed lymphocyte response assay, strong suppression was observed when anti-donor (rat) ICAM-1 mAb was combined with anti-recipient (mouse) LFA-1 mAb. Likewise, significant prolongation of islet xenograft survival was observed with these mAbs. Thus, 0.05 mg of anti-mouse LFA-1 mAb and anti-rat ICAM-1 mAb given on days 0 and 1 produced significant prolongation of graft survival over the control (51+/-20 days vs. 10+/-3 days, P<0.0001), but not when anti-mouse ICAM-1 mAb was combined with anti-mouse LFA-1 mAb (13+/-3 days). In this species combination, mouse T cells were able to proliferate in the presence of rat antigen-presenting cells (APCs) in a cell number-dependent manner, but not in the presence of mouse APCs. The binding assay showed that LFA-1 molecules on mouse T cells can bind immobilized rat ICAM-1 molecules. These results suggest that rat ICAM-1 molecules on APCs can interact with mouse LFA-1 molecules on T cells across a species barrier and that this binding generates the consequent immune responses leading to rejection. mAb treatment against these adhesion molecules of recipient as well as donor is crucial for preventing rejection in a xenogeneic transplantation model.

Animals↗
PubMed1998

Three novel missense mutations in unrelated Japanese patients with type I and type II protein S deficiency and venous thrombosis.

A molecular analysis of protein S deficiency in three unrelated Japanese patients was performed. An approximately 50% reduction in both functional and immunologic levels of protein S was detected in the plasmas from two unrelated patients, designated protein S Osaka 1 and protein S Osaka 2. An approximately 50% reduction in the functional level, but a normal immunologic level of protein S, was detected in plasma from a third patient, designated protein S Osaka 3. All of the exons and exon/intron junctions of the protein S gene were studied using a strategy combining polymerase chain reaction amplification and rapid non-radioactive single-strand conformational polymorphism analysis. We identified a G-to-A change in exon X of the protein S gene in protein S Osaka 1. This mutation resulted in the substitution of Gly for Ser at position 295 in the sex hormone-binding globulin-like region. In protein S Osaka 2, a G-to-C change at the position of the 3' end of exon III was identified, leading to the amino acid substitution of Val46 by Leu in the aromatic stack region. In protein S Osaka 3, an A-to-G change in exon II was identified, leading to the substitution of Lys9 by Glu in the Gla domain. It was concluded that the Gly295-to-Ser mutation and Val46-to-Leu mutation cause type I protein S deficiency and that the Lys9-to-Glu mutation causes type II deficiency.

Adult↗
PubMed1998

Determination of a safe vascular clamping method for liver surgery: evaluation by measuring activation of calpain mu.

OBJECTIVE: To determine the safest method of hepatic vascular clamping associated with the least ischemia-reperfusion injury of the liver during liver surgery. SETTING: University laboratories. SUBJECTS: Sixty-five adult male Wistar rats. METHODS: The hilar area of the left lateral and median lobes of rat liver was clamped for 10 minutes (group 1), 15 minutes (group 2), or 20 minutes (group 3) followed by 5 minutes of reperfusion. The procedure was repeated for a total period of ischemia of 60 minutes in each group. Control rats underwent laparotomy without vascular clamping. In addition to histological examination, we determined calpain mu activity, a marker of liver injury, by Western blotting using specific antibodies against the intermediate (activated) and proactivated forms of calpain mu. Measurements were performed at the end of ischemia and after 2 hours of reperfusion. We also determined the degradation of talin, an intracellular substrate of calpain mu, by Western blotting. RESULTS: The level of adenosine triphosphate and energy charge at 2 hours after reperfusion did not change after ischemia-reperfusion irrespective of the duration of ischemic cycle. After 60 minutes of intermittent ischemia followed by 2 hours of reperfusion, cell membrane bleb formation, calpain mu activation, and talin degradation were detected in groups 2 and 3 but not in group 1. CONCLUSION: The safest method of hepatic vascular clamping that produces a minimum or no ischemia-reperfusion injury is 60 minutes of 6 cycles of 10-minute vascular clamping interrupted by 5 minutes of reperfusion.

Animals↗
PubMed1998

Protection of islet allografts transplanted together with Fas ligand expressing testicular allografts.

Fas ligand (FasL) is highly expressed in testicular tissues and thought to be responsible for protection from allograft rejection by inducing apoptosis of anti-graft activated T cells. FasL-expressing islets have been shown to induce a granulocyte-mediated inflammatory reaction. We investigated whether a graft can be protected from alloimmune responses by manipulating the Fas/FasL-system. We transplanted allogeneic islets under the kidney capsule of streptozotocin-induced diabetic mice together with testicular tissue. Significant prolongation of survival of C3H islet allograft was observed in C57BL/6 (B6) recipients transplanted with C3H testicular tissue, but not in those transplanted with C3H-gld testicular tissue expressing non-functional FasL. No significant prolongation was observed in B6-lpr recipients expressing non-functional Fas. Immunohistochemical staining of C3H testicular tissue in the composite graft showed a high expression of FasL, but not that of the C3H-gld testicular tissue. In situ terminal deoxynucleotidyl transferase-mediated dUDP-biotin catalysed DNA nick-end labelling (TUNEL) staining of a composite graft of C3H islet and testicular tissue in B6 recipients demonstrated extensive apoptosis of infiltrating mononuclear cells around the graft. The protective effect of C3H testicular tissue was abrogated when anti-FasL monoclonal antibody was administered i.p. postoperatively. Our results suggest that FasL-positive testicular allografts protect composite islet allografts and indicate that manipulation of Fas/FasL mediated apoptosis is a suitable strategy for controlling rejection of islet allografts.

Animals↗
PubMed1998

A role for local calcium gradients upon hypoxic injury in human umbilical vein endothelial cells (HUVEC).

Upon hypoxic injury, bleb formation is an early event of cell damage observed in a variety of cell types. Although a rise in cytosolic free Ca2+ ([Ca2+]i) has been considered to be involved in this process, the exact relationship between these phenomena remains ill-defined. In order to examine the relationship between bleb formation, and [Ca2+]i or nuclear free Ca2+ ([Ca2+]n), we analyzed [Ca2+]i and [Ca2+]n in HUVEC during hypoxic injury using confocal laser scanning microscopy. [Ca2+]i and [Ca2+]n were measured using Fluo-3, and cell viability and mitochondrial membrane potential were assessed by the exclusion of propidium iodide (PI) and rhodamine 123, respectively. After the initiation of hypoxia, [Ca2+]i and [Ca2+]n rose gradually up to 15 min reaching peak values of 447 +/- 62 and 516 +/- 105 nM, respectively, which was accompanied by a decrease in rhodamine 123 fluorescence and an increase in PI-stained cells. Bleb formation was observed after [Ca2+]i and [Ca2+]n had reached their peak values and the number of blebs increased thereafter. Confocal z-sectioning images revealed a localized increase in [Ca2+]i at the bleb forming site and this localized elevation in [Ca2+]i was observed before bleb formation in the corresponding area. In conclusion, bleb formation induced by hypoxic stress appears to involve Ca(2+)-dependent reactions that are linked to a regional elevation of [Ca2+]i.

Analog-Digital Conversion↗