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Biomedical subjects

N Kuroda

Publications and source records attributed to N Kuroda.

At least 73 records · Page 4Linked to original sources
PubMed2001

Paxillin: application of immunohistochemistry to the diagnosis of chromophobe renal cell carcinoma and oncocytoma.

Paxillin is a cytoskeletal protein that was recently identified as a component of focal adhesions and links between F-actin and integrin. In this study, 91 renal tumors--65 conventional renal cell carcinomas (RCCs), 14 papillary RCCs, 6 chromophobe RCCs, 4 collecting duct carcinomas, 2 oncocytomas--were investigated for the immunohistochemical expression of paxillin. In a normal kidney, paxillin was predominantly expressed in the cytoplasm of distal tubules, loops of Henle, collecting ducts, and vascular smooth muscle cells. In all of the chromophobe RCCs and oncocytomas, strong expression of paxillin was observed in the tumor cytoplasm. In contrast to these tumors, conventional RCCs, papillary RCCs, and collecting duct carcinomas showed negative reactions for paxillin except for one case in each subgroup with weak reactivity. An immunoblot analysis confirmed the presence of paxillin in healthy kidney, chromophobe RCC, and oncocytoma. These data suggest that paxillin possibly plays a role in signal transductions as a focal adhesion intervening between tumor cells and the extracellular matrix in renal tumors with collecting duct phenotypes such as chromophobe RCCs and oncocytomas, but not in conventional RCCs. In addition, paxillin may be an available marker in distinguishing chromophobe RCCs from conventional or papillary RCCs.

Adenoma, Oxyphilic↗
PubMed2001

CD34 positive stromal cells in gastric adenocarcinomas.

AIMS: To investigate the role of CD34 positive stromal cells, namely dendritic interstitial cells, in gastric carcinomas, the distribution of CD34 positive stromal cells in gastric adenocarcinomas (GCs), with special reference to two histological types (diffuse (D-type) and intestinal (I-type)), was examined. METHODS: In total, 55 surgically resected GCs (15 D-type and 40 I-type) and their normal tissues were examined. To distinguish CD34 positive stromal cells from vascular endothelial cells and to recognise the tumour border, immunostaining for CD34, CD31, and low molecular weight cytokeratins was performed. RESULTS: In the 15 D-type GCs, eight of the nine D-type GCs invading the muscularis propria and subserosa had a large number of CD34 positive stromal cells in the tumour stroma, whereas all six D-type GCs confined to the submucosa had no CD34 positive stromal cells in the tumour stroma. All of the 40 I-type GCs had no CD34 positive stromal cells, regardless of tumour depth. CONCLUSIONS: These results suggest that CD34 expression in stromal cells is associated with progression of D-type GCs, and that absence of expression is also seen in I-type GCs that are progressing.

Adenocarcinoma↗
PubMed2001

Solution-phase automated synthesis of tripeptide derivatives.

An improved general method for automated synthesis of tripeptides was developed, in which methanesulfonic acid (MSA) was used in place of trifluoroacetic acid (TFA), thus making it possible to avoid, 1) corrosion of the apparatus by strong acid vapor, 2) formation of emulsions, and 3) use of the restricted solvent, dichloromethane. As an application of the automated synthesis apparatus, 216 fragment tripeptide derivatives were synthesized systematically using the MSA method, in excellent yield and with increased efficiency.

Automation↗
PubMed2001

Application of an automated synthesis suite to parallel solution-phase peptide synthesis.

An in-house developed automated synthesis suite was used to prepare a library of 72 tetrapeptide derivatives, the starting materials for pharmaceutically attractive pentapeptides, employing a convergent strategy. An initial set of 18 dipeptides were synthesized on a large-scale (100-1000 g) using automated synthesis workstations, and then 72 tetrapeptides were synthesized on a medium scale (5-10 g) using an automated system. Each di- or tetrapeptide was prepared in a single operating cycle using a modified methanesulfonic acid method, then a sub-library of 56 pentapeptides were synthesized in parallel, on a small-scale (100 mg-1 g) using a robotic workstation.

Carboxylic Acids↗
PubMed2001

Separation of sympathomimetic amines of abuse and related compounds by micellar electrokinetic chromatography.

Separation of twelve sympathomimetic amines and related compounds by micellar electrokinetic chromatography (MEKC) with UV absorbance detection is described. These amines were well separated within 25 min using 50 mM sodium tetraborate solution containing 15 mM sodium dodecylsulfate (SDS) of pH 9.3 as a running solution and detected at 210 nm. MEKC was performed with an applied voltage of 13 kV at 25 degrees C using a fused-silica capillary (50 cm x 75 mm i.d.) with effective length of 37.5 cm. The detection limits of these compounds were in the range from 4 to 97 fmol/injection at a signal-to-noise ratio (S/N) of 3. The reproducibility of the method expressed as relative standard deviation (RSD) for within-day (n=6) and between-day (n=5) assays was less than 4.8 and 8.8%, respectively. The proposed method could be applied to the determination of an anorectic drug, phentermine, in Chinese tea with a detection limit of 99 microg/g (105 fmol/injection, S/N=3).

Calibration↗
PubMed2001

Relationship between the QT indices and the microvolt-level T wave alternans in cardiomyopathy.

The relationship between the QT indices and microvolt-level T wave alternans (TWA) is unknown in cardiomyopathy, so the present study examined 86 patients with cardiomyopathy who experienced TWA during exercise testing (EXT). The QT interval (QT), duration from the Q wave to the peak of the T wave (QTp), duration from the peak to the end of the T wave and the dispersion of these parameters were measured by 12-lead electrocardiogram at rest and during EXT. In dilated cardiomyopathy (DCM), TWA was positive (TWA+) in 19 patients and negative (TWA-) in 17. No significant difference was observed between the TWA+ and TWA- groups in any parameter. In hypertrophic cardiomyopathy (HCM), TWA was positive in 24 patients and negative in 12. Max QTc, max QTpc and mean QTpc during EXT in the TWA+ group were significantly longer than those in the TWA- group. The sensitivity of TWA for ventricular tachycardia (VT) was high in DCM and HCM, and that of max QTc >500 ms during EXT for VT was high in HCM (93%). TWA is a useful predictor for VT in DCM and HCM, and prolonged max QTc during exercise has a prognostic value in HCM. Repolarization abnormality during exercise plays an important role in the genesis of VT in cardiomyopathy.

Adult↗
PubMed2001

Bioassay for neutron-dose estimations of three patients in the JCO criticality accident in Tokai-mura by measuring beta-ray emitters.

The measurement of beta-emitters in biological samples (hair, urine and bone) from three patients in the JCO criticality accident was performed to assess the neutron dose to individuals. The result of the measurements of 32P in hair and urine collected immediately after the accident showed that sufficient 32P activities had been induced in the hair by fast neutrons and in the urine by thermal neutrons to know the severity of the exposure to the individuals and to the position. From the measurement of 32P and 45Ca in bone from various anatomical parts of two patients who died 82 and 210 days after the accident, it was suggested that the distribution of the induced beta-emitters activities could prove the position and posture of the patients at the moment of exposure.

Beta Particles↗
PubMed2001

Simultaneous determination of phenolic xenoestrogens by solid-phase extraction and high-performance liquid chromatography with fluorescence detection.

A highly sensitive and selective method for simultaneous determination of some hydroxyl group-containing endocrine disruptors, including bisphenol A (BPA), bisphenol B (BPB), bisphenol E (BPE), bisphenol F (BPF) and 4-nonylphenol (4-NP), was developed. The method consists of precolumn derivatization of the analytes, solid-phase extraction (SPE) and subsequent chromatographic analysis by high-performance liquid chromatography (HPLC) with fluorescence detection. 4,4'-Cyclohexylidenebisphenol (BPZ) was used as an internal standard. Derivatization was carried out using 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) as a label. Parameters of the derivatization reaction (temperature, time, concentration of reagent, stability, etc.) and of the solid-phase extraction (recovery, solvent, etc.) were studied in detail. Detection limits of compounds studied in standard solutions ranged from 0.08-1.3 ppb (ng/ml). The proposed method was successfully applied to plastic samples; BPA was found in both polycarbonate and polyvinyl chloride plastics, while 4-NP was found in plastics made of polyvinyl chloride and another polymer.

Benzhydryl Compounds↗
PubMed2001

[Introduction and clinical evaluation of a new non-invasive cardiac output monitor (NICO) based on Fick partial CO2 rebreathing method].

A newly developed non-invasive monitor, NICO (Novametrix Medical Systems Inc.), measures cardiac output based on changes in respiratory CO2 concentration caused by a brief period of rebreathing. By applying modified form of the CO2 Fick principle, cardiac output is calculated. We determined the accuracy and precision of this technique (RBCO) by comparing it with continuous thermodilution technique (TDCCO) and pulse dye densitometry technique (PDD). The overall difference between RBCO and TDCCO(n = 46) was -0.21 +/- 1.43 (bias +/- 2 SD)l.min-1. On the other hand, the overall difference between RBCO and PDD (n = 53) was -0.1 +/- 2.04 (bias +/- 2 SD)l.min-1. The degree of accuracy of RBCO was thought to be the same as those of TDCCO and PDD. We expect that NICO will be a useful cardiac output monitor in any method of general anesthesia in which PA catheterization is difficult or not indicated.

Anesthesia, General↗
PubMed2000

High-performance liquid chromatography with peroxyoxalate chemiluminescence detection of bisphenol A migrated from polycarbonate baby bottles using 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride as a label.

A highly sensitive and selective high-performance liquid chromatographic method with peroxyoxalate chemiluminescence detection for the determination of bisphenol A at sub-ppb levels is described. Bisphenol A was derivatized with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride and the excess unreacted reagent was removed by a simple solid-phase extraction procedure with recoveries of approximately 60%. The separation was carried out isocratically on an ODS column and the derivatized bisphenol A was detected by peroxyoxalate chemiluminescence. A mixture of bis[2-(3,6,9-trioxadecanyloxycarbonyl)-4-nitrophenyl]oxalate (0.6 mM) and hydrogen peroxide (25.0 mM) dissolved in acetonitrile was used as a chemiluminescence reagent solution with a mixture of imidazole-HNO3 buffer (40.0 mM, pH 7.0): acetonitrile (17:83, v/v) as a mobile phase. The linear standard curve was obtained over the range from 0.57 (2.5) to 22.8 (100) ppb (nM) (r=0.996) with a detection limit of 0.38 ppb (2.8 fmol on column) at a signal-to-noise ratio of 3. The method was successfully applied to the determination of bisphenol A in hot water in contact with commercially available baby bottle samples.

Benzhydryl Compounds↗
PubMed2000

Quantification of methamphetamine, amphetamine and enantiomers by semi-micro column HPLC with fluorescence detection; applications on abusers' single hair analyses.

Achiral and chiral semi-micro column high-performance liquid chromatographic methods with fluorescence detection to determine methamphetamine and amphetamine in human hair are described. These compounds were extracted into 5% trifluoroacetic acid (TFA) in methanol, derivatized with 4-(4,5-diphenyl-1H-imidazol-2-yl)-benzoyl chloride and separated either on a 250 x 1.5 mm i.d. octadecyl-silane (ODS) or a 150 x 2 mm i.d. OD-RH column. Linear calibration curves extending over a wide range of concentration that covers the practical samples were obtained for amphetamine, methamphetamine and their enantiomers (r = 0.999). Resolution values for amphetamine and methamphetamine enantiomers were 3.4 and 1.1, respectively. Intra- and inter-day variations of both the methods were not larger than 8.9% expressed as relative standard deviations (n >/= 5). The limits of detection at a signal-to-noise ratio of 3 obtained by both the methods were in the range of 1.0-4.7 fmol/5 microL injection with the achiral method being more sensitive. Abusers' hair samples were analyzed by the two methods and only the S(+)-enantiomers were found in eight Japanese abusers' hair samples. The achiral method was used to study the concentrations of these compounds in single black and white hair strands of abusers.

Amphetamine↗
PubMed2000

Molecular cloning and linkage analysis of complement C3 and C4 genes of the Japanese medaka fish.

The thioester-containing complement components, C3 and C4, are believed to have arisen by gene duplication from a common ancestor, and the mammalian C4 gene resides in the vicinity of the C2 and B genes within the major histocompatibility complex (MHC) class III region. To analyze the evolution of both the complement system and the MHC, we determined the complete primary structures of two C3 genes, termed Orla C3-1 and Orla C3-2, and one C4 gene, termed Orla C4, of a teleost, Japanese medaka fish (Oryzias latipes), by analyzing cDNA clones isolated from a liver library constructed using the inbred AA2 strain. The deduced basic structures of Orla C3-1, C3-2, and C4, such as the subunit chain structure, the thioester site, and the proteolytic activation site, are similar to their mammalian counterparts. However, the catalytic His residue which greatly increases the rate of thioester reaction, is replaced by Ala in Orla C3-2, implying functional differentiation between two C3 molecules. Mapping analysis revealed a close linkage between the C3-1 and C3-2 genes, indicating that they arose by a local duplication rather than by a genome-wide tetraploidization. The C4 gene belongs to a different linkage group, and no linkage was observed among the C3, C4, Bf/C2, MHC class I, and MHC class II loci. These results suggest that the MHC class III complement region was established in the tetrapod lineage, or lost in the teleost lineage.

Amino Acid Sequence↗
PubMed2000

Evolution of and obstacles in surgical treatment for hepatocellular carcinoma over the last 25 years: differences over four treatment eras.

This study was designed to clarify what differences the last 25 years have made in surgical results for patients with hepatocellular carcinoma (HCC). We examined results for 716 hepatectomized patients in four treatment eras: first era (1973-1980; n = 58), second era (1981-1985; n = 155), third era (1986-1990; n = 243), and fourth era (1991-1997; n = 260). Patient background, tumor characteristics, type of hepatectomy, treatment for intrahepatic recurrences, and surgical results in the four eras were compared by univariate analysis to clarify the factors that have contributed to or impeded progress in the surgical treatment of HCC. Although there were no significant chronological differences in liver pathology and surgical resectability, operative mortality was reduced to 2% in the fourth era, from 29% in the first era. With an increasing proportion of early-stage HCCs (TNM, stages I and II), the cumulative survival rate at 5 years improved in the course of the eras in our overall population of patients (12%, 31%, 38%, and 51%, respectively, for the first, second, third, and fourth eras) and in a subset of the population divided according to tumor stage. Also, we found a chronological improvement in the survival rate at 3 years after intrahepatic recurrence (10%, 28%, 36%, and 44%, respectively in the first second, third, and fourth eras). This improvement was associated with the establishment of an early detection program for intrahepatic recurrences. However, the recurrence rate was similar in any subset of the population through the four eras. Although this univariate study could not determine independent factors that contributed to the chronological progress in results for HCC surgery in the four eras, it is conceivable that the establishment of indication criteria for hepatectomy, an early detection program for primary and recurrent lesions, and the introduction of multimodal treatment for recurrence were contributory factors in this improvement. A strategy for alleviating the frequent recurrences originating from posthepatectomy metachronous carcinogenesis remains to be established.

Analysis of Variance↗
PubMed2000

Does topical cooling alleviate ischemia/reperfusion injury during inflow occlusion in hepatectomy? Results of an experimental and clinical study.

This study was undertaken to evaluate whether topical cooling can alleviate ischemia/reperfusion injury, after continuous inflow occlusion during hepatectomy. Using a canine model of 70% partial liver ischemia (60 min), alteration in the subcellular (cytoplasm, mitochondria, nucleus) elements calcium, sodium, potassium, and chloride, and liver functions following reperfusion were compared between control livers and livers subjected to topical cooling down to 23 degrees +/- 4.9 degrees C by seeding ice slush over the ischemic lobe. The elements were determined by X-ray microanalysis using liver biopsy specimens. A similar clinical study was undertaken examining ten patients with hepatocellular carcinoma and chronic liver disease who underwent right-sided segmentectomy under continuous right inflow occlusion, five of whom were given topical cooling and five of whom were not. In the experimental study, postreperfusion worsening of liver function tests was significantly suppressed in the cooling group, which was associated with the suppression of subcellular Ca, Na, and Cl increases and K decreases after reperfusion. In the clinical study, the occlusion time was significantly longer in the hypothermic patients than in the normothermic patients, but no significant differences in postoperative liver function or postischemic increases in Ca, Na, or Cl and decreases in K were observed. These experimental and clinical findings suggest that topical cooling alleviates ischemic insult and enhances safe prolonged inflow occlusion.

Aged↗
PubMed2000

Appearance of denuded hepatic stellate cells and their subsequent myofibroblast-like transformation during the early stage of biliary fibrosis in the rat.

To investigate the early in vivo response of hepatic stellate cells in biliary fibrosis, we examined rat livers during the first 7 days after bile duct ligation using light microscopy, immunohistochemistry, electron microscopy, and immunoelectron microscopy. At day 1 after bile duct ligation, alpha-smooth muscle actin-positive fibroblasts appeared and then increased in number around the proliferating bile ductules. With time, the destruction of the external limiting plate became accentuated because of the invasion of the proliferating bile ductules and periductural fibrosis. At day 7, stromal cells containing fat droplets appeared in the fibrous tissue adjacent to the periportal parenchyma; these are termed denuded hepatic stellate cells. In the fibrous tissue disconnected from the liver parenchyma, the denuded hepatic stellate cells were replaced by myofibroblast-like cells. Meanwhile, the expression of transforming growth factor-beta1 on biliary epithelial cells increased. These results indicate the dual origin of myofibroblasts in experimental biliary fibrosis, the periductural and periductal fibroblasts in the initial stage, and the denuded hepatic stellate cells in the subsequent stage. These two types of stromal cells may undergo myofibroblastic transformation by the transforming growth factor-beta1 secreted by the proliferating biliary epithelial cells.

Actins↗
PubMed2000

Adenoid basal carcinoma of the uterine cervix: a case report with ultrastructural findings.

Adenoid basal carcinoma of the uterine cervix is a rare tumor with a favorable prognosis. A case of adenoid basal carcinoma (ABC) of the uterine cervix was studied using light and electron microscopy. The patient was a 74-year-old Japanese woman who had undergone hysterectomy due to cervical intraepithelial neoplasia 3. Incidentally, ABC was found in the resected uterus. The tumor cells made small nests and infiltrated the cervical portion of the uterus. In the nests, glands, cribriform patterns with glandlike structures, and squamous differentiation were seen. Immunohistochemically, the glandlike structures were positive for laminin and type IV collagen. Ultrastructurally, the tumor cells had irregular nuclei, scanty cytoplasm, and cribriform patterns in which glandlike structures were covered with basal lamina. No myoepithelial differentiation of the tumor cells was seen. These findings suggest a similarity between adenoid basal carcinomas and adenoid cystic carcinomas. Furthermore, both tumors are considered to originate in the reserve cells of the uterine cervix. Because their outcomes are different, they should be distinguished from each other.

Aged↗
PubMed2000

Mesangial myofibroblastic transformation in steroid-dependent minimal change nephrotic syndrome.

Patients with minimal change nephrotic syndrome (MCNS) occasionally show frequent relapses with proteinuria after cessation of steroid treatment, even though no significant pathological abnormalities are found in the glomeruli, compared with those in nonrelapsed and good-prognosis cases of MCNS. To resolve this contradiction, we immunohistochemically and ultrastructurally examined a biopsied renal tissue of a patient who showed glomerular features of MCNS and frequent clinical relapses. Immunohistochemistry demonstrated the overexpression of alpha-smooth muscle actin (ASMA) and vimentin in glomerular mesangial cells despite no mesangial cell proliferation, compared with nine nonrelapsed cases of MCNS. These facts may be an important clue to the investigation of the pathogenesis of steroid-dependent MCNS with frequent relapses. Furthermore, the immunohistochemical examination of ASMA and vimentin may be useful to detect mesangial myofibroblastic transformation that is not demonstrated in conventional light microscopy and immunofluorescence study.

Actins↗