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Biomedical subjects

S Mikami

Publications and source records attributed to S Mikami.

At least 19 recordsLinked to original sources
PubMed2001

Ischemic preconditioning attenuates cardiac sympathetic nerve injury via ATP-sensitive potassium channels during myocardial ischemia.

BACKGROUND: During myocardial ischemia, massive norepinephrine (NE) is released from the cardiac sympathetic nerve terminals, reflecting the sympathetic nerve injury. A brief preceding ischemia can reduce infarct size; this is known as ischemic preconditioning (PC). The effect of PC on sympathetic nerves, however, including its underlying mechanisms in dog hearts, has remained unclear. Thus, this study was designed to elucidate whether the activation of ATP-sensitive potassium (K(ATP)) channels is involved in the mechanism of cardiac sympathetic nerve protection conferred by PC. METHODS AND RESULTS: Interstitial NE concentration was measured by the in situ cardiac microdialysis method in 45 anesthetized dogs. Five minutes of ischemia followed by 5 minutes of reperfusion was performed as PC. In the controls, the dialysate NE concentration (dNE) increased 15-fold after the 40-minute ischemia. PC decreased dNE at 40-minute ischemia by 59% (P<0.01), which was reversed by glibenclamide. A K(ATP) channel opener, nicorandil (25 microg. kg(-1). min(-1) IV), decreased dNE at 40 minutes of ischemia by 76% (P<0.01), which was also reversed by glibenclamide. During the PC procedure, no significant increase in dNE was detected, even with the uptake-1 inhibitor desipramine. CONCLUSIONS: Cardiac sympathetic nerve injury during myocardial ischemia was attenuated by PC via the activation of K(ATP) channels, but the trigger of the PC effect is unlikely to be NE release in dog hearts.

Adenosine Triphosphate↗
PubMed2001

Triethylborane-induced radical reactions with gallium hydride reagent HGaCl2.

[see reaction]. A gallium hydride reagent, HGaCl2, was found to act as a radical mediator, like tributyltin hydride. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium trichloride combined with stoichiometric aluminum hydride as a hydride source.

Journal Article↗
PubMed2001

Comparisons of intraosseous graft healing between the doubled flexor tendon graft and the bone-patellar tendon-bone graft in anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to compare intraosseous graft healing between the doubled flexor tendon (FT) graft and the bone-patellar tendon-bone (BPTB) graft in anterior cruciate ligament (ACL) reconstruction. TYPE OF STUDY: Randomized trial. METHODS: A biomechanical and histologic study was conducted with 24 adult beagle dogs. Bilateral ACL reconstructions were performed in each animal. Autogenous doubled FT and BPTB grafts were used for the left and right knees, respectively. Each end of the 2 grafts was tethered with a polyester suture to a screw post with a washer. The animals were then allowed unrestricted activities in their cages. Eight animals were killed at 3, 6, and 12 weeks, respectively. RESULTS: Histologically, the FT graft was anchored to the tunnel wall with newly formed collagen fibers resembling Sharpey's fibers by 12 weeks. These fibers were more abundant in the anterior (ventral) gap than in the posterior (dorsal) gap. In the BPTB graft, the bone plug was anchored with newly formed bone at 3 weeks, although osteocytes in the plug trabeculae were necrotic for 12 weeks. Degeneration of the tendon-bone junction in the plug progressed at 6 weeks. Tensile testing showed that the weakest site was different not only between the 2 grafts but also between the observation periods. In the FT graft, the weakest site was the graft-wall interface at 3 weeks and the intraosseously grafted tendon at 6 weeks. In the BPTB graft, the weakest site was the graft-wall interface at 3 weeks and the proximal site in the bone plug at 6 weeks. The ultimate failure load of the FT graft was significantly inferior (45.8%) to that of the BPTB graft at 3 weeks (P =.021). At 6 weeks, the load of the FT graft was 85% that of the BPTB graft without a significant difference (P =.395). CONCLUSIONS: As to the clinical relevance, the fixation device chosen for soft-tissue fixation appears to be more important than comparing it to the BPTB graft, although this has yet to be conclusively proven.

Animals↗
PubMed2001

Loss of syndecan-1 and increased expression of heparanase in invasive esophageal carcinomas.

Heparan sulfate proteoglycans play important biological roles in cell-cell and cell-matrix adhesion, and are closely associated with growth factor actions. Loss of syndecan-1, a cell surface-bound heparan sulfate proteoglycan, has been reported for advanced head and neck carcinomas, and expression of endoglycosidic heparanase, which cleaves heparan sulfate glycosaminoglycans (HS-GAGs), is associated with invasion and metastatic potential of malignant tumors. Paraffin sections of 103 primary esophageal squamous cell carcinomas were immunohistochemically examined for the expression of syndecan-1 core protein, HS-GAGs and heparanase protein, and the results were compared with various clinicopathological parameters, such as invasion depth. For 16 cases, fresh tumor samples were quantitatively analyzed for heparanase and syndecan-1 mRNA expression by real-time RT-PCR in addition to the immunohistochemical studies. Syndecan-1 core protein and HS-GAGs expression was significantly decreased in pT2 and pT3 cases compared with their pTis and pT1 counterparts. Decreased expression of core protein and HS-GAGs was correlated with the incidence of lymphatic invasion, and venous involvement. Furthermore, decreased expression of HS-GAGs was correlated positively with the incidence of nodal metastasis and distant organ metastasis, and negatively with the grade of tumor cell differentiation. The percentage of cytoplasmic heparanase protein-positive cases increased significantly in pT2 and pT3 cases compared to that in pTis and pT1 cases, and this was associated with lymphatic invasion, and venous and lymph nodal involvement. The level of heparanase mRNA was inversely correlated with the degree of HS-GAGs expression rather than core protein. In conclusion, loss of syndecan-1 and heparanase overexpression in esophageal squamous cell carcinomas are closely associated with malignant potential. Regarding the mechanism of loss of HS-GAGs, heparanase upregulation appears to play an important role.

Adult↗
PubMed2001

Relationship of the microvascular type to the tumor size, arterialization and dedifferentiation of human hepatocellular carcinoma.

Unlike normal liver with the sinusoids, hepatocellular carcinomas (HCCs) possess capillaries. Whether these capillaries derive from the sinusoids remains unclear in human HCCs. This study aimed to examine sinusoidal capillarization in human HCCs and its relationship to the tumor size, arterialization and dedifferentiation. Thirty-eight HCCs with a diameter of 10 - 140 mm were pathologically and angiographically examined. By electron microscopy, the microvasculature of tumors was classified into sinusoidal, intermediate and capillary types, which were all negative, partially positive and all positive, respectively, for four parameters, i.e., endothelial defenestration, continuous basement membrane, lack of Kupffer cells, and lack of lipid-containing hepatic stellate cells. Well-, moderately and poorly differentiated HCCs displayed sinusoidal / intermediate / capillary types, intermediate / capillary types and only capillary type, respectively, suggesting the transition from the sinusoids to capillaries in well-differentiated (and probably moderately differentiated) HCCs. Furthermore, well-differentiated HCCs with a diameter of less than 30 mm often received preferential portal venous blood, while moderately and poorly differentiated ones were all supplied with arterial blood, indicating a relationship between dedifferentiation and arterialization. In contrast, the microvascular type displayed no significant relationship with tumor size or arterialization in well-differentiated HCCs. The present study has demonstrated that sinusoidal capillarization occurs in human well-differentiated HCCs and seems to be related to dedifferentiation of parenchymal tumor cells, but not to tumor size or arterialization.

Adult↗
PubMed2001

New compound heterozygous mutation in the CYP17 gene in a 46,XY girl with 17 alpha-hydroxylase/17,20-lyase deficiency.

BACKGROUND: 17alpha-Hydroxylase/17,20-lyase deficiency is caused by a defect of P450c17 which catalyzes both 17alpha-hydroxylase and 17,20-lyase reactions in adrenal glands and gonads. RESULTS: In the present study, we analyzed the CYP17 gene in a Japanese patient with 17alpha-hydroxylase/17,20-lyase deficiency. The patient was a phenotypic girl and referred to us for right-sided inguinal hernia at the age of 4 years. Biopsy of the herniated gonad showed testicular tissue. The karyotype was 46,XY. At 6 years of age, hypertension was clearly recognized and the patient was diagnosed as having 17alpha-hydroxylase/17,20-lyase deficiency based on the clinical and laboratory findings. Analysis of the CYP17 gene revealed a compound heterozygous mutation. One mutation was an undescribed single nucleotide deletion at codon 247 in exon 4 (CTT to CT: 247delT) and the other was a missense mutation resulting in a substitution of His to Leu at codon 373 in exon 6 (CAC to CTC: H373L), which has been previously shown to abolish both 17alpha-hydroxylase and 17,20-lyase activities. The functional expression study of the 247delT mutant showed that this 247delT mutation completely eliminates both 17alpha-hydroxylase and 17,20-lyase activities. CONCLUSIONS: Together, these results indicate that the patient is a compound heterozygote for the mutation of the CYP17 gene (247delT and H373L) and that these mutations inactivate both 17alpha-hydroxylase and 17,20-lyase activities and give rise to clinically manifest 17alpha-hydroxylase/17,20-lyase deficiency.

Adrenal Hyperplasia, Congenital↗
PubMed2001

[Evaluation of endoscopic papillary balloon dilation (EPBD) using one-step catheter for removal of common bile duct stones].

We compared the results of EPBD in 18 patients using one-step catheter (one-step group) with those in 46 patients using usual two-step catheter (two-step group). The frequency of endoscopy and bile duct clearance were the equal in both groups. Pancreatitis occurred in only one patient of two-step group. Elevations of the amylase values were the equal in both groups. Amylase values after EPBD tended to decrease in 11 patients whose amylase values were above 500 IU/l before EPBD. Using one-step catheter in EPBD was useful for removing common bile duct stones easily and safety.

Aged↗
PubMed2000

Erythrocytosis caused by an erythropoietin-producing hepatocellular carcinoma.

A case of erythrocytosis caused by a hepatocellular carcinoma (HCC) that produced erythropoietin (Epo) is described. A 64-year-old man, with a huge HCC tumor in the right lobe of the liver, showed a high concentration of hemoglobin and increased levels of serum Epo, alpha-fetoprotein (AFP), and protein induced by vitamin K absence II (PIVKA-II). Right lobectomy of the liver was performed. Histological findings of the specimen showed a moderately differentiated HCC. The existence of Epo was confirmed immunohistochemically only in the tumor tissue and not in the normal liver tissue. Erythrocytosis disappeared and the serum levels of Epo, AFP, and PIVKA-II returned to the normal range after the operation. Within 2 months after the operation, recurrent tumors appeared in the remnant liver, and the patient died 13 months after the operation.

Biomarkers↗
PubMed2000

Course before and after percutaneous transhepatic portal vein embolization of a patient with cholangiocarcinoma monitored by scintigraphy with Tc-99m galactosyl human serum albumin.

Percutaneous transhepatic portal vein embolization (PTPE) causes atrophy of the embolized lobe and compensatory hypertrophy of the nonembolized lobe, and improves the safety of hepatectomy. We report a patient with cholangiocarcinoma who underwent embolization of both anterior and posterior branches of the right portal vein before hepatectomy. Scintigraphy with Tc-99m galactosyl human serum albumin was performed before and 4 weeks after PTPE. After PTPE, the right lobe of the liver was atrophied and the left lobe of the liver was enlarged, compared with before PTPE. The receptor index of the entire liver was almost unchanged before and after PTPE, but the right lobe receptor index after PTPE was 23% less than the pre-PTPE value, whereas the left lobe receptor index had increased 37%. Scintigraphy with Tc-99m galactosyl human serum albumin is useful for evaluating segmental functional reserve before and after PTPE.

Aged↗
PubMed2000

Additional hepatocellular carcinomas undetectable before surgery.

The presence of small additional hepatocellular carcinomas (HCCs) undetectable before hepatic resection is a crucial topic for hepatic surgeons. We assessed the incidence of pathologically diagnosed multiple HCCs in 267 patients who underwent hepatic resection for HCC. Ninety-five additional HCC nodules were detected in 72 of the patients (27%). The survival rate of these 72 patients was significant worse than for the 195 with single nodular HCC (p = 0.0013). Twenty-one (22%) were detected before surgery, 29 (31%) during surgery, and 45 (47%) on pathologic examination after surgery. The mean nodule diameters for each group were 2.1, 1.0, and 0.9 cm, respectively (p < 0.0001). None of the 21 nodules detected before surgery was well differentiated, whereas 30 of the 74 nodules in the other two groups were well-differentiated. Although the mean nodule diameter of the well-differentiated HCC group was the smallest, there was no significant difference among the three groups assigned according to tumor differentiation (p = 0.2355). Altogether, 9 of 16 patients with additional nodules detected before surgery (56%) and 49 of 59 with additional nodules detected during or after surgery (88%) had cirrhosis of the liver. The odds ratio for detecting a new HCC nodule during or after surgery in the presence of cirrhosis was 5.444 (p = 0.0087). Improvement in the detection of small additional HCC nodules before and during surgery and meticulous follow-up after surgery are necessary for patients with cirrhosis. For patients without cirrhosis, surgical treatment may be performed according to the results of preoperative imaging studies.

Analysis of Variance↗
PubMed2000

Computed tomography during arteriography and arterial portography in small hepatocellular carcinoma and dysplastic nodule: a prospective study.

We studied the relationship between the findings of computed tomography during arteriography (CTA) and computed tomography during arterial portography (CTAP), and pathologic findings of 81 small nodular lesions (3 cm or less in diameter) in resected liver specimens. The 81 lesions consisted of 8 dysplastic nodule (DN) lesions, 23 well-differentiated hepatocellular carcinomas (early HCCs) and 50 moderately or poorly differentiated HCCs (advanced HCCs). We also performed standard computed tomography (CT), digital subtraction angiography (DSA), magnetic resonance imaging (MRI), and ultrasonography, and compared sensitivities with CTA, CTAP, or combination of CTA and CTAP with other imaging methods. Forty-four of the 50 advanced HCCs, 12 of the 23 early HCCs, and none of 8 DNs hyperattenuated with CTA and hypoattenuated with CTAP. The sensitivity for the early HCCs was significantly higher for CTA and CTAP in combination as compared with DSA or standard CT. The sensitivity for the advanced HCCs was significantly higher for CTA and CTAP in combination than with DSA. The sequential changes of the blood supply from the portal vein to the hepatic artery during the development of the HCCs were observed. Although CTA and CTAP in combination were useful for the distinction of advanced HCC from early HCC or DN, CTA and CTAP used in combination were not superior to CTA alone in the detection of such lesions.

Adult↗
PubMed2000

Analysis of the FGFR3 gene in Japanese patients with achondroplasia and hypochondroplasia.

It has been reported that mutations in the FGFR3 gene cause autosomal dominant forms of dwarfism, achondroplasia (ACH) and hypochondroplasia (HCH). In the present study, we analyzed the FGFR3 gene in 26 Japanese patients with ACH and 14 with HCH. Genomic DNAs of the patients were isolated from whole blood. For the ACH patients, a 164-bp fragment of the FGFR3 gene that spans the entire transmembrane domain was amplified by polymerase chain reaction (PCR), and the PCR products were analyzed by direct sequencing of the PCR products and by digestion of the PCR products with restriction enzymes. For the HCH patients, a 206-bp fragment of the FGFR3 gene which encodes a part of the TK1 domain was amplified, and the PCR products were directly sequenced. The heterozygous G380R mutations were identified in all of the 26 ACH patients, whereas the heterozygous N540K mutations were identified in 8 out of 14 HCH patients. These results were consistent with previous reports from abroad.

Achondroplasia↗
PubMed2000

[Total hip and knee arthroplasty for arthropathy in a hemophiliac].

We evaluated the medium-term follow-up results, effectiveness, and suitability of arthroplasty for hemophilic arthropathy. We performed 26 total knee and 9 total hip arthroplasty operations on hemophilic patients between 1988 and 1998 under general anesthesia and appropriate hemostatic management. Postoperative treatment for hemophilic arthropathy is the same as that for osteoarthritis and rheumatoid arthritis. After their operations, patients experienced relief from pain and intra-articular bleeding in affected joints but only marginal improvement in the range of motion. In general, total joint arthroplasty is not indicated for young patients. However, arthropathy can have a severe impact on the active life of patients during their youth. For severe hemophilic arthritis, total knee and hip arthroplasty can lead to a pain-free and improved quality of life. We believe total knee and hip arthroplasty is a good solutions for hemophiliac arthropathy before severe deformity occurs. Although treated relatively young hemophilic patients, age was not considered to be a contraindication.

Adult↗
PubMed1999

Impact of a single exercise bout on energy expenditure and spontaneous physical activity of obese boys.

The main objective of the present study was to determine whether a structured, laboratory-based exercise task would modify the energy expenditure (EE) and the pattern of spontaneous physical activity (PA) of obese boys on the day of an exercise laboratory visit and on the following day. Fourteen 10- to 15-y-old moderately obese (36.6+/-3.3% fat) boys volunteered. They each had three laboratory visits, I wk apart. In one visit, they performed a strenuous 50-min cycling task; in another, a 30-min medium-intensity cycling task; and in another (which served as placebo), they did not exercise. PA was monitored the day before (d 1), during (d 2), and after (d 3) each laboratory visit by use of a heart rate monitor and a 12-h recall interview. EE was calculated from minute-by-minute heart rate and each child's predetermined relationship between oxygen uptake and heart rate. EE and PA were analyzed from 1300 to 1900 h each day using 15-min intervals. EE tended to decrease (p < 0.087) in the afternoon of all d 2 compared with d 1, and it increased on d 3 after the medium-intensity exercise (p < 0.0005). EE during d 2 and 3 combined, compared with d 1, decreased after the high-intensity exercise (534.2 versus 564.3 kJ/h, p < 0.05). It increased after the medium-intensity exercise (561.8 versus 526.7 kJ/h, p = 0.052) and was not affected after the placebo visit (589.4 versus 574.3 kJ/h). Time spent outdoors was consistently reduced on the day of laboratory visit compared with the day before and after the visit, regardless of the contents of intervention. In conclusion, a single laboratory visit is followed by a reduction in EE and PA on the day of intervention. However, its effect on EE the following day may be dose dependent: medium-intensity exercise induces an increase in EE, but high-intensity exercise causes a decrease in EE. One implication is that intervention by physical training should employ medium-intensity exercise to enhance the EE of obese boys.

Adolescent↗
PubMed1998

Hepatocellular carcinoma with chondrosarcomatous variation: case report with immunohistochemical findings, and review of the literature.

Hepatocellular carcinoma with chondrosarcomatous variation is very rare. We report a case with the results of pathology examination, and review the literature. The patient, a 72-year-old may had a very large tumor in the liver revealed during follow-up for diabetes mellitus. The liver mass, which was 14 cm in diameter, was diagnosed as hepatocellular carcinoma by abdominal ultrasonography. Anterior segmentectomy and partial liver resection were performed. Histopathology examination revealed that the tumor consisted of two different components: the major one was hepatocellular carcinoma (HCC), which occupied most of the tumor; and a sarcomatous component, which occupied a smaller area, and included spindle-shaped cells with chondroscarcomatous variation. Intrahepatic metastases and tumor thrombi of HCC were also found in portal and hepatic veins. Investigations of the immunohistochemical localization of keratin (KRT), vimentin (VMT), and S-100 protein (S 100) were performed by the avidin-biotin complex method. Some of the spindle cells were immunohistochemically positive for both KRT and VMT, and the chondrosarcomatous cells were positive for S 100. These results strongly suggested that the sarcomatous lesion resulted from a sarcomatous change of HCC.

Aged↗
PubMed1998

Immunohistochemical analysis of TrkA neurotrophin receptor expression in human non-neuronal carcinomas.

The Trk family of tyrosine protein kinase receptors plays a significant role in the development and maintenance of neural tissues. It has been recently shown that Trk receptors are also expressed by a wide range of normal non-neuronal tissues in humans in a cell type-specific manner. In the present study, the expression patterns of TrkA in 337 non-neuronal invasive carcinomas of 15 different human tissues were investigated immunohistochemically. Overall, 133 (39%), 101 (30%) and 103 (31%) tumors exhibited strong, moderate and no TrkA immunoreactivity, respectively. Esophageal and thyroid carcinomas expressed high levels of TrkA, whereas the levels in gastric and colon cancers were low. TrkA expression was detected not only in carcinomas originating from TrkA-positive normal counterpart tissues, including the esophagus, breast, lung and uterus, but also in those from TrkA-negative tissues/cells of the thyroid, liver and ovary. Immunostaining for nerve growth factor-beta, the specific ligand for TrkA, in esophageal and breast carcinomas demonstrated its immunoreactivity in stromal fibroblasts and some TrkA-expressing tumor cells. These results suggest that paracrine/autocrine regulation via stromal/tumoral NGF-tumoral TrkA interaction may be involved in the growth of certain non-neuronal carcinomas.

Breast Neoplasms↗
PubMed1998

G370C mutation in the FGFR3 gene in a Japanese patient with thanatophoric dysplasia.

Thanatophoric dysplasia (TD) is a sporadic lethal skeletal dysplasia with micromelic shortening of the limbs, relative macrocephaly, platyspondyly and reduced thoracic cavity. It has recently been reported that TD is caused by mutations in the FGFR3 gene. In the present study, we report a missense mutation in the FGFR3 gene in a Japanese patient with TD. The patient was noticed to have typical features of TD type 1 (TD1) at birth. The genomic DNAs of the patient and his parents were isolated from whole blood. DNA fragments of the FGFR3 gene were amplified by polymerase chain reaction, and directly sequenced. The patient was revealed to be heterozygous for a missense mutation G370C, changing codon 370 (GGC) encoding Gly to TGC encoding Cys, but his parents did not have the G370C mutation. The G370C mutation introduces an unpaired cysteine residue in the extracellular domain of FGFR3, which may result in formation of an intermolecular disulfide bond between two mutant FGFR3 monomers and their constitutive activation. In conclusion, we have identified the G370C mutation in the FGFR3 gene in a Japanese TD1 patient.

Alleles↗