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Biomedical subjects

S Wada

Publications and source records attributed to S Wada.

At least 127 records · Page 7Linked to original sources
PubMed1999

Preoperative assessment of extrahepatic bile duct carcinoma using three-dimensional intraductal US.

BACKGROUND: We investigated the utility of a new imaging modality, three-dimensional intraductal ultrasonography (US), for staging bile duct cancer. METHODS: In eight patients with extrahepatic bile duct carcinoma, two- and three-dimensional intraductal US was used to assess tumor invasion of the right hepatic artery, portal vein, and pancreatic parenchyma before resection. The findings were correlated with histologic information from the resected specimen. RESULTS: Three-dimensional intraductal US enabled accurate assessment of tumor invasion of the right hepatic artery in 88% of cases, the portal vein in 100%, and pancreatic parenchyma in 100%. Two-dimensional intraductal US enabled accurate assessment of invasion of these structures in 88%, 88%, and 88% of cases. CONCLUSIONS: Three-dimensional intraductal US is useful in assessing tumor stage in bile duct carcinoma.

Aged↗
PubMed1999

Bile duct wall thickness measured by intraductal US in patients who have not undergone previous biliary drainage.

BACKGROUND: We investigated the bile duct wall thickness measured on intraductal US in patients who had not undergone biliary drainage, with special attention to the influence of cancer at the distal bile duct, bile duct stones, obstructive jaundice, longitudinal cancer extension, and primary sclerosing cholangitis on wall thickness. METHODS: The study included 183 patients. Patients who had undergone previous biliary drainage were excluded. Intraductal US was performed by the transpapillary route with use of a thin-caliber ultrasonic probe (2.0 mm diameter, 20 MHz frequency). The bile duct wall thickness (width of the inside hypoechoic layer) was retrospectively measured on US images. RESULTS: Bile duct wall thicknesses of the common hepatic duct for the control group (n = 95), cancer at the distal bile duct group (n = 9), bile duct stone group (n = 56), and obstructive jaundice group (n = 17) were 0.6 +/- 0.3 mm (mean +/- SD), 0.8 +/- 0.5 mm, 0.8 +/- 0.6 mm, and 0.8 +/- 0. 5 mm, respectively. No significant differences (p > 0.05) were found between them. However, wall thickness for the cancer extension to the common hepatic duct group (n = 4, 2.0 +/- 0.4 mm) and sclerosing cholangitis group (n = 2, 2.5 +/- 0.4 mm) were significantly greater than in the other groups (p < 0.005). CONCLUSIONS: In patients who have not undergone previous biliary drainage, the bile duct wall thickness was not thicker in patients with obstructive jaundice. However, the duct wall was significantly thicker in patients with either longitudinal cancer extension or primary sclerosing cholangitis compared with that of other groups.

Adult↗
PubMed1999

How many biopsies should be performed during percutaneous transhepatic cholangioscopy to diagnose biliary tract cancer?

BACKGROUND: The sensitivity of biopsy in the diagnosis of cholangiocarcinoma using percutaneous transhepatic cholangioscopy is not well defined. METHODS: Patients with a biliary tract malignancy (n = 52) underwent directed biopsy during percutaneous transhepatic cholangioscopy using a 1.8 mm diameter forceps. Histologic findings were correlated with endoscopic appearance. RESULTS: A diagnosis of carcinoma was made in all four patients with a tumor of the major duodenal papilla and in all 15 patients with a polypoid bile duct tumor with two biopsies from the mass. In 19 patients with stenotic bile duct cancer, a positive diagnosis was made in 95% of cases when three biopsies were taken from the margin of the stenotic area. When cholangioscopy showed a tortuous, dilated vessel (n = 10), the diagnosis of cancer was made with two biopsies taken from the margin of the stenosis. In 14 patients with metastatic bile duct cancer, the diagnosis was made in only 43% of cases when three biopsies were taken from the margin of the stenosis. When combined with results from the three biopsies taken from within the area of stenosis, the sensitivity for diagnosing pancreatic cancer improved from 20% to 60%. CONCLUSIONS: Directed cholangioscopic biopsies are highly sensitive for the diagnosis of cholangiocarcinoma but less sensitive for cancer metastatic to the bile duct. The numbers and locations of the biopsies required to make a diagnosis of carcinoma depend on the origin and cholangioscopic appearance of the tumor.

Adult↗
PubMed1999

Structure and UV absorption of QCCs: carbonaceous dust analogues.

"Quenched Carbonaceous Composites (QCCs)" are carbonaceous interstellar dust analogues synthesized in the laboratory from a hydrocarbon plasma. We produced new types of carbonaceous condensates from the ejecta of plasma with mixtures of methane and hydrogen as source gases. We find that QCC with an absorbance peak at 220 nm is composed of onion-like spherules, and QCCs with an absorbance peak at 230-240 nm are composed of polyhedral particles. The onion-like QCC contains aromatic hydrogen bonds, and it shows the 3.3 and 11.4 micrometers absorption bands. The QCC with an absorbance peak at 230-240 nm is composed of ribbons with bent graphitic layers. This suggests that the carrier of the interstellar 220 nm extinction band might also be an emitter of the interstellar diffuse emission bands.

Astronomical Phenomena↗
PubMed1999

Structure and NIR feature of QCC: a laboratory analog of carbon dust.

We have produced thin films of quenched carbonaceous composite (QCC) by hydrocarbon plasma deposition. The effect of thermal annealing on QCC has been investigated to understand how QCC, as a laboratory analog of carbon dust, is transformed in the warm environment around evolved stars. Spectroscopic measurements have indicated that, by heating, the proportion of aromatic sp2 CH bonds increases relative to sp3 CH bonds. Carbon onion-like spherules of approximately 10 nm in diameter are found with electron microscopic images after "graphitization" of thermal annealing.

Astronomical Phenomena↗
PubMed1999

Vegetal cell fate specification and anterior neuroectoderm formation by Hroth, the ascidian homologue of orthodenticle/otx.

To obtain insights into the mechanisms of gastrulation and neural tube formation, we studied the function and regulation of expression of Hroth, the ascidian homologue of orthodenticle/otx, during embryogenesis. Microinjection of synthetic Hroth mRNA into fertilized eggs led to embryos with an expanded trunk and a reduced tail. In these embryos, development of notochord and muscle was effected. Also, Hroth overexpression caused ectopic formation of anterior neuroectoderm, along with suppression of epidermis development, even in the absence of cell-cell interaction. Furthermore, we demonstrated that ectodermal expression of Hroth requires an inductive influence from the vegetal hemisphere cells. These data suggest roles of Hroth in both specification of mesoendodermal cells and anterior neuroectoderm formation.

Animals↗
PubMed1999

Cloning and embryonic expression of Hrsna, a snail family gene of the ascidian Halocynthia roretzi: implication in the origins of mechanisms for mesoderm specification and body axis formation in chordates.

snail family genes encode a transcription factor with specific zinc finger motifs. In vertebrates, they are expressed in the entire mesoderm in early embryogenesis and later in the paraxial mesoderm and the tail-bud, suggesting roles in specification and morphogenesis of the paraxial mesoderm. In the present study, a snail family gene Hrsna from a member of the chordates, an ascidian (Halocynthia roretzi), was cloned to obtain an insight into the origin of the mechanisms of mesoderm specification and body axis formation as observed in vertebrates. Expression of Hrsna during ascidian embryogenesis was found to be quite similar to that of vertebrate snail genes. First, before gastrulation, Hrsna was initially expressed in most precursors of mesodermal tissues including the notochord where As-T, the ascidian homolog of brachyury, was expressed. Hrsna expression persisted in the paraxial mesoderm, the mesenchyme and muscle, but not in the notochord precursors. Also, just as vertebrate snail family genes are expressed in the border of the neural plate that develops into dorsal neural tube and neural crest cells, so Hrsna expression was detected in the precursors of lateral and dorsal regions of the neural tube. However, Hrsna expression was not detected in the tip of the tail, unlike in vertebrate counterparts. In the light of the present findings, similarity and dissimilarity of mechanisms governing mesoderm specification and body axis formation between ascidians and vertebrates are discussed.

Amino Acid Sequence↗
PubMed1999

Why the flexible cystoscope has not yet been widely introduced?: A questionnaire to Japanese urologists.

BACKGROUND: The flexible cystoscope has not been as widely accepted in the field of urology as in other fields. The results of this investigation provided implications for determining the reasons for the under-use of flexible cystoscopy as well as for the drawbacks of the flexible cystoscope. METHODS: We performed an investigation by sending a questionnaire to urologists asking them to compare the flexible cystoscope with the rigid cystoscope in order to determine why use of the former lags behind that of the latter. RESULTS: We received answers from 420 urologists. We classified the urologist into four groups according to their years of experience. We also classified patients, for whom flexible cystoscopy was carried out, into four groups. The majority of the urologists in all groups thought that the flexible cystoscope provided a small field of vision and rough images. Urologists thought that the flexible cystoscope was inferior to the rigid cystoscope in terms of manipulability in biopsy. However, doctors who examined many patients using flexible cystoscopy believed that it was advantageous in terms of decreasing the patients' pain and they have experienced no problem in clinical practice. CONCLUSIONS: Lack of experience in using the flexible cystoscope appears to be the main reason for the negative impression it generates. The flexible cystoscope can be routinely used in place of the rigid counterpart for urological investigations and it is recommended that it be used more widely for the benefit of the patients.

Cystoscopes↗
PubMed1999

Influence of bile duct diameter on the therapeutic quality of endoscopic balloon sphincteroplasty.

BACKGROUND AND STUDY AIMS: Endoscopic balloon sphincteroplasty (EBS) has been reported to be a safe alternative to sphincterotomy for the treatment of bile duct stones. We evaluated the factors which influence the therapeutic efficacy of EBS. PATIENTS AND METHODS: A total of 118 consecutive patients with bile duct stones were treated by EBS. After conventional endoscopic retrograde cholangiography (ERC), EBS was done using a biliary dilation catheter (balloon diameter, 8mm). The duct was then cleared using Dormia baskets or retrievel balloon catheters. When the stones were greater than 8 mm in diameter, mechanical lithotripsy was performed before extraction. Complete stone clearance was assessed by balloon-ERC and intraductal ultrasonography. Therapeutic efficacy was assessed using univariate and multivariate analysis. Patients were classified into three groups according to the bile duct diameter: nondilated (bile duct < or = 10 mm), mildly dilated (10 mm < bile duct < or = 15 mm), and severely dilated group (bile duct > 15 mm). RESULTS: In 113 of 118 (96%) patients, the stones were completely cleared with one to six endoscopic sessions (mean 1.6 sessions). In the nondilated group, 24 of 28 (85%) patients were cleared of stones in one session (mean 1.2 sessions), without the use of mechanical lithotripsy in 23 of 28 (82 %) patients. In the mildly dilated group, 23 of 38 (61 %) patients were cleared of stones in one session (mean 1.5 sessions). In contrast, in the severely dilated group, only 16 of 52 (31 %) patients were cleared of stones in one session (mean 2.0 sessions). Stone size, number of stones, and use of mechanical lithotripsy were independent variables which influenced the success of stone clearance in one session after EBS. CONCLUSION: When EBS is done in patients with bile duct stones, bile duct diameter may be a good indicator of therapeutic efficacy. In patients with severely dilated bile ducts (> 15 mm), EBS is of limited effectiveness.

Aged↗
PubMed1999

Reduced expression of the CDK inhibitor p27(KIP1) in rat two-stage bladder carcinogenesis and its association with expression profiles of p21(WAF1/Cip1) and p53.

The cyclin-dependent kinase (CDK) inhibitor p27(KIP1) exerts its growth suppressive effects by targeting the cyclin-CDK complexes. Reduced protein levels of p27(KIP1) have been reported in numerous human cancers and this has been attributed to increased degradation. However, few reports have addressed the significance of p27(KIP1) expression in chemical carcinogenesis of rodents. In a rat two-stage urinary bladder carcinogenesis model, with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) initiation followed by promotion with sodium L-ascorbate (Na-AsA), we evaluated the expression of p27(KIP1) protein using immunohistochemistry during various stages of urinary bladder carcinogenesis. In addition, we evaluated the mRNA expression profiles for p27(KIP1), p21(WAF1/Cip1) and p53 in tumors. Fisher 344 rats were initiated with 0.05% BBN in the drinking water for 4 weeks and then administered 5% Na-AsA in the diet. Immunohistochemical examination revealed p27(KIP1) protein to be constitutively expressed in normal urothelium, simple hyperplasia and in most papillary and nodular (PN) hyperplasias and small papillomas, but diminished or absent in large papillomas and in transitional cell carcinomas. An inverse correlation between expression of p27(KIP1) and cell proliferation was generally observed. Quantitation of mRNA by multiplex reverse transcription-PCR showed a significant downregulaton of p27(KIP1), p21(WAF1/Cip1) and p53 mRNA in tumors. More than 50% reduction in p27(KIP1) mRNA expression was observed in 42 and 47% of tumors at weeks 18 and 24, respectively; similar reduction in p21(WAF1/Cip1) mRNA expression was observed in 58 and 73% of tumors at weeks 18 and 24, and in p53 mRNA expression in 50 and 73% of tumors at weeks 18 and 24, respectively. None of the 25 tumors we examined by PCR-single-strand conformational polymorphism analysis had p53 mutations. These data imply that abnormal down-regulation of p27(KIP1), p21(WAF1/Cip1) and/or p53 in tumor cells may contribute to the malignant progression of tumors during rat two-stage bladder carcinogenesis.

Animals↗
PubMed1999

Induction of macrophage migration inhibitory factor in human ovary by human chorionic gonadotrophin.

The role of macrophage migration inhibitory factor (MIF) in human ovarian function remains obscure. The aim of this study was to investigate how MIF was related to ovulation by quantitative analysis of serum, follicular fluid and culture medium of granulosa cells obtained from in-vitro fertilization (IVF) and embryo transfer patients. Serum MIF concentrations in ovarian stimulation cycles for IVF-embryo transfer were higher at day 1 (median 92.6 ng/ml), which took place 35 h after human chorionic gonadotrophin (HCG) administration and just before the retrieval of oocytes, than those before day -6 (12.1 ng/ml), at day -5 to about day 0 (17.5 ng/ml) or at day 2 to about day 14 (8.2 ng/ml). MIF concentrations in the follicular fluid (113.4 ng/ml) obtained in ovarian stimulation cycles for IVF-embryo transfer were significantly higher than in serum (72.0 ng/ml) collected at the same time. MIF concentrations in the follicular fluid in natural cycles were higher in the ovulatory phase (51.6 ng/ml) than in the late follicular phase (13.8 ng/ml). MIF concentrations in the culture media of granulosa cells increased from 3.2 ng/ml to 7.2 ng/ml with HCG stimulation, and decreased from 2.4 ng/ml to 1.2 ng/ml when stimulation was withheld. These results indicate that HCG can induce the elevation of serum and follicular fluid MIF concentrations through the stimulation of ovarian cells, and that MIF is probably involved in the mechanism of ovulation.

Adult↗
PubMed1999

Teas and other beverages suppress D-galactosamine-induced liver injury in rats.

We compared the effects of various types of beverages (teas, coffee, and cocoa) on D-galactosamine-induced liver injury by measuring plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in 7-wk-old male Wistar rats. The effects of five fractions extracted with different organic solvents from green tea, different types of dietary fibers, and some short chain fatty acids were also investigated. All of the beverages tested significantly suppressed D-galactosamine-induced enhancement of plasma enzyme activities when powdered beverages were added to the diet (30 g/kg) and fed to rats for 2 wk. Plasma ALT activities were 1155 +/- 82 [micromol/(min.L), control], 289 +/- 61 (green tea), 626 +/- 60 (roasted green tea), 471 +/- 84 (puerh tea), 676 +/- 69 (oolon tea), 423 +/- 76 (black tea), 829 +/- 53 (coffee), and 885 +/- 89 (cocoa). The profile of AST activities was similar. The caffeine-containing fraction from green tea had no significant effect, whereas the other four fractions, including the soluble fiber fraction, significantly suppressed liver injury. In addition to tea fibers, many other types of dietary fiber (hemicellulose, chitin, chitosan, alginate, pectin, guar gum, glucomannan, and inulin, but not cellulose) had liver injury-preventive effects when added to the diet (30 g/kg), suggesting that liver injury-prevention may be one of the general effects of dietary fibers. Of three short-chain fatty acids tested (acetate, propionate, and butyrate), only acetate prevented liver injury when added to the diet (15 g/kg), supporting the possibility that the liver injury-preventive effect of dietary fibers may be mediated at least in part by certain organic acids. These results suggest that several beverages possess preventive effects on certain types of liver injury, such as that induced by D-galactosamine, and that different constituents of high and low molecular weights contribute to the liver injury-preventive effects of green tea.

Alanine Transaminase↗
PubMed1999

Up-regulation of the alpha2,6-sialyltransferase messenger ribonucleic acid increases glycoconjugates containing alpha2, 6-linked sialic acid residues in granulosa cells during follicular atresia of porcine ovaries.

The sugar chains in cellular glycoconjugates have many biological functions. Extensive morphological development and remodeling occur in the ovary of female animals. This caused us to study glycobiological characteristics of ovarian cells, particularly granulosa cells that undergo apoptosis during follicular atresia. The lectin Sambucus sieboldiana agglutinin (SSA) specific for Siaalpha2,6Gal/GalNAc showed positive staining for granulosa cells only in atretic follicles of porcine ovaries by lectin histochemistry. Lectin blot analysis for SSA demonstrated specific glycoproteins only in atretic follicles. Furthermore, we performed analysis of backbone structures of SSA-positive glycans carried by granulosa cell glycoproteins increased during atresia by glycosidase treatment. Most of these structures were Siaalpha2,6Galbeta1,4GlcNAc on complex-type N-glycans, suggesting that only ST6Gal I of four distinct alpha2,6-sialyltransferases catalyzes alpha2,6-sialic acid transfer in most of the increased glycoproteins of granulosa cells during follicular atresia. Reverse transcription-polymerase chain reaction analysis demonstrated that the expression of ST6Gal I mRNA was up-regulated in granulosa cells during atresia. These results suggested that the alteration of glycoconjugates by ST6Gal I in granulosa cells during atresia is involved in some processes of ovarian follicular atresia and granulosa cell apoptosis.

Animals↗
PubMed1999

Induction of apoptosis signal regulating kinase 1 (ASK1) after spinal cord injury in rats: possible involvement of ASK1-JNK and -p38 pathways in neuronal apoptosis.

The aims of this study were to clarify the mechanism of cell death by apoptosis in the spinal cord after traumatic injury, and to examine the role of the mitogen-activated protein kinase (MAPK) pathways in the transmission of apoptosis signals. The rat spinal cord, experimentally injured by extradural static weight-compression, was studied by hematoxylin and eosin staining, Nissl-staining, terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick-end labeling (TUNEL) staining, and immunostaining using polyclonal antibodies against Apoptosis Signal-regulating Kinase 1 (ASK1), c-Jun N-terminal kinase (JNK), and p38 MAPK. TUNEL-positive cells were present at all stages studied until 7 days after injury, and percentage positivity for these cells was maximal at 3 days after injury. Electron microscopic analysis revealed the occurrence of apoptosis in both neuronal cells and glial cells. TUNEL-positive glial cells were stained by oligodendrocyte-specific maker. Expression of ASK1 was maximal at 24 h after injury in the gray matter and at 3 days after injury in the white matter. Following the expression of ASK1, activated forms of JNK and p38 were observed in apoptotic cells detected by the TUNEL method. Colocalization of ASK1 and activated JNK or activated p38 was observed in the same cell. These findings suggest the involvement of the stress-activated MAPK pathways including ASK1 in the transmission of apoptosis signals after spinal cord injury.

Animals↗
PubMed1999

The effect of immunosuppressive agents (FK-506, rapamycin) on renal P450 systems in rat models.

It is well known that cyclosporin, rapamycin and FK-506 (tacrolimus) are metabolized by the liver microsomal cytochrome P450 enzyme system. Although there have been reports of interaction between these drugs and the renal P450 enzyme system, differences among these immunosuppressants has not been comprehensively demonstrated. We have studied the individual capacities of these immunosuppressants to induce renal microsomal P450 enzymes similar to CYP2B4 and CYP4A2 by examining renal function in treated rats, and have correlated the results by means of biochemical, immunological and immunohistochemical assays of renal P450 enzymes. Cyclosporin caused impairment of renal function with an increase in renal-specific P450 content, but FK-506 and rapamycin did not. Laurate omega- and (omega-1)-hydroxylase activity increased in rats treated with rapamycin but decreased in those treated with FK-506. Prostaglandin A1 (PGA1) omega-hydroxylase activity increased in rats treated with FK-506 but was reduced by treatment with cyclosporin. Aminopyrine N-demethylase activity increased in rats treated with cyclosporin or FK-506, but not in those treated with rapamycin. Western-blot analysis revealed significant induction of P450, (similar to CYP2B4 of the rabbit P450 isozyme) in kidneys from rats treated with cyclosporin but not in those from rats receiving FK-506 or rapamycin. Histochemical studies clearly demonstrated a form of P450 such as CYP4A2 in the proximal tubules of rats treated with cyclosporin, but not in those of rats treated with FK-506 or rapamycin. These results show that although cyclosporin has a strong effect on renal P450 systems and induces such a system in kidney cortex (microsomal P450), FK-506 and rapamycin have no substantial effect on the induction of renal P450. These findings might clarify the nephrotoxicity induced by these immunosuppressive drugs.

Aminopyrine N-Demethylase↗
PubMed1999

Anteroposterior patterning of the epidermis by inductive influences from the vegetal hemisphere cells in the ascidian embryo.

Patterning along the anteroposterior axis is a critical step during animal embryogenesis. Although mechanisms of anteroposterior patterning in the neural tube have been studied in various chordates, little is known about those of the epidermis. To approach this issue, we investigated patterning mechanisms of the epidermis in the ascidian embryo. First we examined expression of homeobox genes (Hrdll-1, Hroth, HrHox-1 and Hrcad) in the epidermis. Hrdll-1 is expressed in the anterior tip of the epidermis that later forms the adhesive papillae, while Hroth is expressed in the anterior part of the trunk epidermis. HrHox-1 and Hrcad are expressed in middle and posterior parts of the epidermis, respectively. These data suggested that the epidermis of the ascidian embryo is patterned anteroposteriorly. In ascidian embryogenesis, the epidermis is exclusively derived from animal hemisphere cells. To investigate regulation of expression of the four homeobox genes in the epidermis by vegetal hemisphere cells, we next performed hemisphere isolation and cell ablation experiments. We showed that removal of the vegetal cells before the late 16-cell stage results in loss of expression of these homeobox genes in the animal hemisphere cells. Expression of Hrdll-1 and Hroth depends on contact with the anterior-vegetal (the A-line) cells, while expression of HrHox-1 and Hrcad requires contact with the posterior-vegetal (the B-line) cells. We also demonstrated that contact with the vegetal cells until the late 32-cell stage is sufficient for animal cells to express Hrdll-1, Hroth and Hrcad, while longer contact is necessary for HrHox-1 expression. Contact with the A-line cells until the late 32-cell stage is also sufficient for formation of the adhesive papillae. Our data indicate that the epidermis of the ascidian embryo is patterned along the anteroposterior axis by multiple inductive influences from the vegetal hemisphere cells and provide the first insight into mechanisms of epidermis patterning in the chordate embryos.

Animals↗