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Biomedical subjects

M Shimada

Publications and source records attributed to M Shimada.

At least 271 records · Page 15Linked to original sources
PubMed1999

Stretch-activated ion channel blocker gadolinium attenuates ischemic ST-segment elevation in canine myocardium.

Regional transmural ischemia causes both ST-segment elevation and systolic elongation (bulging) of the myocardium. Mechanical stretch might alter the transmembrane potential via stretch-activated ion channels (SAC); however, the role of SAC on ischemic ST-segment elevation has not yet fully studied. The present study investigated the role of SAC in the genesis of ischemic ST-segment elevation in the in-vivo canine heart. In 6 anesthetized dogs, an extracorporeal conduit connected to the left anterior descending coronary artery was occluded for 5 min before and after the intracoronary infusion of gadolinium (Gd, 500 micromol/min). To eliminate the effect of ischemic preconditioning, the bypass was occluded for 5 min before the experiment. Percent systolic shortening (%SS) and percent systolic elongation (%bulging) were measured using a pair of ultrasonic dimension crystals. A unipolar epicardial ECG was monitored at the center of the ischemic area for the measurement of the ST-segment level. At the end of coronary occlusion, there was no difference in the reduction of %SS or the increase of %bulging between before and after infusion of Gd. ST-segment elevation, however, was significantly attenuated by the infusion of Gd. These data demonstrated that the activation of SAC is one cause of ischemic ST-segment elevation.

Animals↗
PubMed1999

Overexpressed lipoprotein lipase protects against atherosclerosis in apolipoprotein E knockout mice.

Lipoprotein lipase (LPL) is known to play a crucial role in lipoprotein metabolism by hydrolyzing triglycerides; however its role in atherogenesis has yet to be determined. We have previously shown that low density lipoprotein receptor knockout mice overexpressing LPL are resistant to diet-induced atherosclerosis due to the suppression of remnant lipoproteins. Plasma lipoproteins and atherosclerosis of apolipoprotein (apo) E knockout mice which overexpress the human LPL transgene (LPL/APOEKO) were compared with those of control apoE knockout mice (APOEKO). On a normal chow diet, LPL/APOEKO mice showed marked suppression of the plasma triglyceride levels compared with APOEKO mice (54 vs. 182 mg/dl), but no significant changes in plasma cholesterol and apoB levels. Non-high density lipoproteins (HDL) from LPL/APOEKO mice had lower triglyceride content, a smaller size, and a more positive charge compared with those from APOEKO mice. Cholesterol, apoA-I, and apoA-IV were increased in HDL. Although both groups developed hypercholesterolemia to a comparable degree in response to an atherogenic diet, the LPL/APOEKO mice developed 2-fold smaller fatty streak lesions in the aortic sinus compared to the APOEKO mice. In conclusion, overproduction of LPL is protective against atherosclerosis even in the absence of apoE.

Animals↗
PubMed1999

Expression of matrix metalloproteinase-9 in surgically resected intrahepatic cholangiocarcinoma.

BACKGROUND: Matrix metalloproteinase-9 (MMP-9) has recently been reported to be related to cancer cell invasion. This study was performed to clarify the expression of MMP-9 in surgically resected intrahepatic cholangiocarcinoma (IHCC). METHODS: In 37 patients with IHCC who underwent a surgical resection, the expression of MMP-9 and the clinicopathologic characteristics of MMP-9-positive IHCC were investigated. The expression of MMP-9 was immunohistochemically detected in 16 (43%) of 37 IHCC. The patients were divided into MMP-9 (-) IHCC (n = 21), MMP-9 (+) IHCC (n = 12), and MMP-9 (++) IHCC (n = 4). RESULTS: The survival rate after surgical resection in patients with MMP-9 (-), (+), and (++) IHCC, was 66%, 39%, and 0% at one year, 50%, 32% and 0% at 3 years, respectively (P = .001). The incidence rate of lymph node metastasis was 6 (28%) of 21 in MMP-9 (-) patients, 7 (58%) of 12 in MMP-9 (+) patients and 4 (100%) of 4 in MMP-9 (++) patients. The incidence rate of lymph node metastasis increased in proportion to an increase in the expression of MMP-9 in IHCC (P = .02). Recurrence in the lymph node was more common in patients with MMP-9 (+) and (++) cancers than in those with MMP-9 (-) cancers. CONCLUSIONS: The expression of MMP-9 in IHCC was a prognostic factor related to lymph node metastasis.

Adult↗
PubMed1999

Mediastinitis due to Gordona sputi after CABG.

Genus Gordona is included in mycolic acid containing bacteria. This genus infection is very rare and occurs classically in immuno-compromised patients. We report a patient who developed mediastinitis due to Gordona sputi after coronary artery bypass grafting (CABG) using left internal mammary artery. Immunocompromised factors were not noticed in this case but postoperative bleeding, the most important risk factor of mediastinitis, was found in his course. The treatment was antibiotic therapy, surgical soft tissue debridement and open irrigation with dilute povidone-iodine solution. However, infectious reaction continued and Gordona sputi repeated cultured from wound. Next procedure, debridement of sternal bone and omental transfer, was performed and skin was closed primarily. Inflammatory reaction was attenuated and the wound was healed Broad debridement and omental transfer were very effective for mediastinitis due to Gordona sputi after CABG.

Actinomycetales Infections↗
PubMed1998

Mice lacking melanin-concentrating hormone are hypophagic and lean.

Feeding is influenced by hypothalamic neuropeptides that promote (orexigenic peptides) or inhibit feeding. Of these, neuropeptide Y (NPY) in the arcuate nucleus and melanin-concentrating hormone (MCH) and orexins/hypocretins in the lateral hypothalamus have received attention because their expression is increased during fasting and because they promote feeding when administered centrally. Surprisingly, absence of the orexigenic neuropeptide NPY fails to alter feeding or body weight in normal mice. As deficiency of a single component of the pathway that limits food intake (such as leptin or receptors for melanocortin-4) causes obesity, it has been suggested that orexigenic signals are more redundant than those limiting food intake. To define further the physiological role of MCH and to test the redundancy of orexigenic signals, we generated mice carrying a targeted deletion of the MCH gene. MCH-deficient mice have reduced body weight and leanness due to hypophagia (reduced feeding) and an inappropriately increased metabolic rate, despite their reduced amounts of both leptin and arcuate nucleus pro-opiomelanocortin messenger RNA. Our results show that MCH is a critical regulator of feeding and energy balance which acts downstream of leptin and the melanocortin system, and that deletion of a gene encoding a single orexigenic peptide can result in leanness.

Animals↗
PubMed1998

Clinicopathologic features of patients with hepatocellular carcinoma surviving >10 years after hepatic resection.

BACKGROUND: This study was performed to clarify the clinicopathologic features of hepatocellular carcinoma (HCC) patients surviving >10 years after hepatic resection. METHODS: Between January 1971 and April 1987, 142 patients underwent hepatic resection. Thirty-nine patients who died of surgical morbidity (surgical mortality rate: 27.5%) were excluded from this study. Among the 103 patients who survived and were observed for >10 years after surgery, 12 patients (11.7%) survived >10 years after hepatectomy. The surviving patients were divided into 2 groups: 10-year survivors (n = 12) and nonsurvivors (n = 91). A comparative study between the two groups was made. RESULTS: Preoperative liver function tests such as the indocyanine green retention test at 15 minutes and albumin levels showed that 10-year survivors had better liver function than nonsurvivors. With regard to virus markers, 5 of 12 patients (41.7%) were positive for hepatitis B surface antigen (HBs-Ag) and the incidence of hepatitis B virus-related HCC was significantly higher than in nonsurvivors (P = 0.020). The results also showed that 4 of 12 long term survivors had hepatitis C virus (HCV) antibody and 1 patient did not have any HCV antibody or HBs-Ag. In two other patients, the HCV antibody was not measured and HBs-Ag was negative. Among four patients with the HCV antibody, the serum HCV RNA concentration, measured by branched DNA probe assay, was <0.5 in 3 patients and 1.72 in 1 patient. Therefore, the HCV RNA concentration tended to be lower in 10-year survivors. Tumor recurrence occurred in 8 of the 10-year survivors. Solitary recurrence was observed in five patients whereas multiple recurrence was observed in three patients. All five patients with solitary recurrence underwent a second resection. CONCLUSIONS: Based on the results of the current study, good liver function, HBs-Ag positivity, and a low concentration of serum HCV RNA in HCV-related HCC should be considered potentially good predictors of a long term survival.

Adult↗
PubMed1998

Estimation of age from the femur of Japanese cadavers.

The purpose of this study is to estimate the age of cadavers by histomorphometry of the femur. Seventy-two Japanese males ranged from 43 days to 92 years old and 26 females ranged from 2 to 88 years old were used. The thickness of sections was adjusted at 50 to 70 microns by grinding with sand paper. The sections were not decalcificated. They were stained with Villanueva's bone staining powder and with thionin dye. Microradiographs of the sections were obtained by the soft X-ray apparatus. The area, maximum and minimum diameter, and perimeter of the perfect osteon and Haversian canal were measured. In addition, the type II osteon number, osteon fragment number, and area of triangle were also determined. All these parameters were examined by an image analyzer. The parameters of the osteon showed high correlation coefficient with age (magnitude of r > 0.77), while those of the Haversian canal were low (magnitude of r < 0.11). All parameters were subjected to multiple regression analysis for producing a multiple regression equation of age estimation. For the stepwise selecting method, the perimeter of osteon, maximum length of the Haversian canal and osteon fragment number were selected for the equation. Their multiple r2 and standard error of estimation were 0.8874 and 6.39, respectively. For the forward selection method, in addition to the above items, three parameters, the maximum length of Haversian canal, triangle area, osteon fragment number were selected. Their multiple r2 and standard error of estimation were 0.9484 and 4.884, respectively. Bone staining was useful to clarify the demarcation between osteon and fragment, leading to an increase in the accuracy of age estimation. However, the entire range from birth to 90 years was difficult to cover for precise age estimation.

Adolescent↗
PubMed1998

Purification and characteristics of a novel cytochrome c dependent glyoxylate dehydrogenase from a wood-destroying fungus Tyromyces palustris.

A new glyoxylate dehydrogenase which catalyzes dehydrogenation of glyoxylate to oxalate in the presence of cytochrome c has been purified as an electrophoretically homogeneous protein from the cell-free extracts of a wood-destroying basidiomycete Tyromyces palustris. The enzymatic reduction of cytochrome c was dependent on glyoxylate which was found to be the best substrate among the compounds tested. The Km value for glyoxylate was determined to be 2.7 mM at the optimal pH (8.0). The UV-visible spectra of the enzyme in oxidized and reduced forms indicate that the enzyme belongs to a family of flavohemoproteins. The flavin nucleotide isolated from the native enzyme by heat denaturation was identified as FMN. The enzyme (Mr 331000) consists of six identical homopolymers (Mr of subunit 59000), which were found to constitute a symmetric octahedral shape by electron-microscopic observation with a negative staining method.

Aldehyde Oxidoreductases↗
PubMed1998

Natural killer cell activity in patients with hepatocellular carcinoma: a new prognostic indicator after hepatectomy.

BACKGROUND: Natural cytotoxicity mediated by natural killer (NK) cells is believed to play an important role in host anticancer defense mechanisms. The aim of this study was to examine the prognostic significance of NK cell activity after hepatectomy in patients with hepatocellular carcinoma. METHODS: The NK cell activity in 210 patients with hepatocellular carcinoma was measured and evaluated in relation to clinicopathologic variables using univariate and multivariate analyses. RESULTS: The NK cell activity was decreased significantly in hepatocellular carcinoma patients compared with the control groups (P < 0.001). No correlation was observed between NK cell activity and the clinicopathologic variables. Multivariate analyses indicated that NK cell activity as well as intrahepatic metastases, platelet count, and serum albumin level were independent prognostic factors. CONCLUSIONS: This study suggests that the preoperative NK cell activity will help predict recurrence and prognosis after hepatectomy in patients with hepatocellular carcinoma.

Adult↗
PubMed1998

Enhanced expression of full-length TrkB receptors in young rat brain with hypoxic/ischemic injury.

Expression of TrkB receptors were studied in the cerebral cortex of normal rats and young rats with hypoxic/ischemic injury. TrkB expressing cells were present in the piriform cortex at birth and increased in number with age, and were finally present in the entire cerebral cortex. Density of TrkB cells reached adult levels at P30. They were morphologically regarded as pyramidal neurons and interneurons. Hypoxic/ischemic injury induced a tentative increase of full-length TrkB receptors. A novel appearance of TrkB expressing neurons and enhanced immunostaining on both cell soma and dendrites were observed in the peri-infarct areas and increased number of TrkB expressing neurons were detected in the contralateral cortex after carotid artery ligation. This increase was no longer evident after 48 h of hypoxia. Double immunostaining using antiserum against GFA or OX-42 revealed no co-localization of TrkB receptors and these molecules, while there were only slight co-localization of TrkB and calbindin-D28k molecules. The altered levels in responses to injury indicate that TrkB may play a crucial role in the early protective mechanism of the neurons with hypoxic/ischemic injury through ligands BDNF and/or NT-4/5.

Age Factors↗
PubMed1998

Design and testing of a new cisplatin form using a base material by combining poly-D,L-lactic acid and polyethylene glycol acid against peritoneal metastasis.

Microspheres containing cisplatin (CDDP) embedded in poly-d,l-lactic acid (PLA) and polyethylene glycol acid (CDDP-PPMS) were developed to improve treatment of malignant effusions. In vitro studies demonstrated that CDDP was released continuously for more than 4 weeks from CDDP-PPMS without initial burst. CDDP-PPMS was compared with CDDP aqueous solution (CDDP-SOL) by i.p. administration in rats for 1) tissue distribution, 2) toxicity and 3) therapeutic effects against Yoshida sarcoma. We found that the CDDP concentration in the omentum was maintained at a higher level than in the CDDP-SOL group, while the particles of CDDP-PPMS were observed in the stomata of the omentum by electron microscopy. Concentrations of CDDP in the lung, liver, kidney and blood were lower in the CDDP-PPMS group than in the CDDP-SOL group. All rats given CDDP-PPMS containing < or = 28 mg/kg were alive, whereas in the CDDP-SOL group, all rats given > or = 16 mg/kg died from side effects. The LD50 of CDDP-PPMS and CDDP-SOL were 32.8 and 14.8 mg/kg, respectively. The survival of rats with peritoneal metastasis was better in the CDDP-PPMS group than in the CDDP-SOL group.

Animals↗
PubMed1998

Soft X-ray multilayer beam splitters.

A semitransparent Mo/Si multilayer beam splitter with a completely self-standing active area (10 x 10 mm) and a flatness of 1.1 nm (r.m.s.) was fabricated. The influence of the roughness of the membrane substrate on the reflectivity of a beam splitter was investigated for different materials and deposition schemes. Precise control of multilayer stress to give a slightly tensile state not only enables the fabrication of a large and flat reflection surface, but also makes it possible to etch away the supporting membrane and obtain a completely self-standing structure. The performance evaluation using synchrotron radiation revealed that the fabricated beam splitter works as a one-to-one beam splitter whose reflectivity and transmittance are both 27% (s-polarization, 45 degrees, lambda = 13.4 nm).

Journal Article↗
PubMed1998

Hypertension, hypertriglyceridemia, and impaired endothelium-dependent vascular relaxation in mice lacking insulin receptor substrate-1.

Insulin resistance is often associated with atherosclerotic diseases in subjects with obesity and impaired glucose tolerance. This study examined the effects of insulin resistance on coronary risk factors in IRS-1 deficient mice, a nonobese animal model of insulin resistance. Blood pressure and plasma triglyceride levels were significantly higher in IRS-1 deficient mice than in normal mice. Impaired endothelium-dependent vascular relaxation was also observed in IRS-1 deficient mice. Furthermore, lipoprotein lipase activity was lower than in normal mice, suggesting impaired lipolysis to be involved in the increase in plasma triglyceride levels under insulin-resistant conditions. Thus, insulin resistance plays an important role in the clustering of coronary risk factors which may accelerate the progression of atherosclerosis in subjects with insulin resistance.

Animals↗
PubMed1998

Comparison between in vivo mutagenicity and carcinogenicity in multiple organs by benzo[a]pyrene in the lacZ transgenic mouse (Muta Mouse).

To evaluate whether the in vivo mutagenicity test system using the lacZ transgenic mice (Muta Mouse) may be applied to carcinogenesis studies, both the in vivo mutagenicity and carcinogenicity of benzo[a]pyrene (BP) was tested in mice under the same administration conditions. The eleven organs of the mice on the 14th day after the final oral administration of BP at a dose of 125 mg kg(-1) day(-1) or corn oil for 5 consecutive days were tested for in vivo mutation by the positive-selection method. The data show that the colon had the highest lacZ mutant frequency (37-fold increase over the spontaneous frequency), followed by the ileum > forestomach > bone marrow, spleen > glandular stomach > liver, lung > kidney and heart. No significant mutations were found in the brain. These results may suggest that, in general, the organs with rapidly proliferative tissues have a marked increase in vivo mutant frequencies under the conditions of this experimental design. The forestomach and lymphatic organs including the spleen (malignant lymphoma) were the main target organs for BP carcinogenesis by 5 daily oral doses of 75 and 125 mg kg(-1) day(-1). These results suggest that the mutation results from the transgenic assay with BP reflect the carcinogenicity of BP in the mouse. They also indicate, however, that the magnitude of the in vivo lacZ mutant frequencies induced by BP in different organs did not fully correlate with the target organs for carcinogenicity.

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

Treatment strategy for patients with cystic lesions mimicking a liver tumor: a recent 10-year surgical experience in Japan.

OBJECTIVE: To clarify some of the difficulties in determining the appropriate surgical indications for cystic lesions mimicking a neoplasm in the liver. DESIGN: A retrospective review of hepatic resections for cystic lesions mimicking a neoplasm in the liver between August 1, 1986, and July 31, 1996. SETTING: A university hospital with a long history of hepatic resection for cystic lesions mimicking a neoplasm in the liver. PATIENTS: Ten patients with such cystic lesions in the liver, who underwent a hepatectomy during a recent 10-year period, were included in this study. MAIN OUTCOME MEASURES: Detailed clinicopathologic data were analyzed, and comparisons were made between the preoperative and postoperative diagnoses. RESULTS: The postoperative diagnoses consisted of cysts, including cysts complicated by an infection or hemorrhage in 7 patients, localized cystic dilation of the bile duct due to hepatolithiasis in 1, cystadenoma in 1, and mucin-producing cholangiocarcinoma in 1. In only one case was postoperative diagnosis identical to the preoperative diagnosis. In one case, an intraoperative pathological examination showed the tumor to be a mucin-producing cholangiocarcinoma instead of a cystadenocarcinoma. A tumor-marker analysis of the fluid in the cystic lesions also did not contribute to a definite diagnosis. Furthermore, cytological examination of the fluid could not completely exclude malignancy. Neither mortality nor morbidity occurred in any of the patients, and their mean length of hospitalization after hepatectomy was only 13.7 days. CONCLUSIONS: The accurate diagnosis of cystic lesions mimicking a tumor remains problematic; however, the results of hepatectomy for such cases are normally satisfactory. Such cystic lesions of the liver should be indicated for hepatectomy whenever the possibility of a cancerous neoplasm cannot be completely ruled out.

Adult↗
PubMed1998

Prognosis of hepatocellular carcinoma with diabetes mellitus after hepatic resection.

We evaluated the effect of diabetes mellitus on the prognosis of hepatocellular carcinoma after an elective hepatic resection. Of the 342 patients who underwent a hepatic resection between April 1985 and March 1995, 87 (25.4%) were diabetic. Postoperative morbidity was more common among diabetics than among nondiabetics (36.0% vs. 22.5%, P = .0239). The postoperative survival rate and the cancer-free survival rate were also better in patients without diabetes than in those with diabetes (P = .0333, P = .0149). The results of a multivariate analysis show diabetes mellitus to be an independent and prognostic indicator after a hepatic resection with hepatocellular carcinoma. According to the above findings, diabetes mellitus is thus considered to be a risk factor for prognosis after hepatic resection in patients with hepatocellular carcinoma.

Adult↗