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Biomedical subjects

K Hara

Publications and source records attributed to K Hara.

At least 397 records · Page 22Linked to original sources
PubMed1995

Detection of amphetamines in urine using head space-solid phase microextraction and chemical ionization selected ion monitoring.

An accurate, simple and rapid method for qualitative and quantitative analysis of amphetamine and methamphetamine in urine was developed using head space-solid phase microextraction and gas chromatography-mass spectrometry/chemical ionization selected iron monitoring. A vial containing a urine sample potassium carbonate and pentadeuterated methamphetamine which was used as an internal standard was heated at 80 degrees C for 20 min. The needle of a solid phase microextraction device was passed through the septum, and the extraction fiber in the needle was exposed for 5 min in the head space of the vial. The needle was removed from the vial and inserted into the injection port of gas chromatograph or gas chromatograph/mass spectrometer. The compounds adsorbed on the fiber were detached by exposing the fiber in the injection port, and analyzed. The proposed method was more than 20 times more sensitive than the conventional head space method.

Amphetamine↗
PubMed1995

Isolation and characterization of novel heterogeneous branched cyclomalto-oligosaccharides (cyclodextrins) produced by transgalactosylation with alpha-galactosidase from coffee bean.

Transgalactosylated derivatives of cyclomalto-hexaose (alpha CD), -heptaose (beta CD), and -octaose (gamma CD) were synthesized by alpha-galactosidase from coffee bean using melibiose as a donor and alpha CD, beta CD or gamma CD as an acceptor. Mono- and di-O-alpha-D- galactosylated CDs were isolated and purified by HPLC. Their structures were elucidated by fast-atom bombardment mass spectrometry (FABMS) and 13C NMR spectroscopy. For structural determination of positional isomers of 6(1),6n-di-O-alpha-D-galactosyl-CDs, digestion products with cyclodextrin glucanotransferase were analyzed by HPLC and FABMS.

Carbohydrate Conformation↗
PubMed1995

Interleukin-3-associated expression of gangliosides in mouse myelogenous leukemia NFS60 cells introduced with interleukin-3 gene: expression of ganglioside GD1a and key involvement of CMP-NeuAc:lactosylceramide alpha 2-->3-sialyltransferase in GD1a expression.

Murine interleukin-3 (IL-3)-associated expression of gangliosides has been investigated using a gene transfection technique. A murine IL-3 cDNA was introduced into the parental NFS60-17 cells that was exclusively dependent on IL-3. We analyzed the glycosphingolipids from the parental cells and the transfected cells by fast atom bombardment mass spectrometry analyses and/or immunostaining techniques using specific antibodies. Two major gangliosides, IV3NeuAc-GgOse4Cer (GM1b) and IV3-NeuAc,III6NeuAc-GgOse4Cer (GD1 alpha), were expressed, in the parental cells. By contrast, in the IL-3 gene-transfected cells, a ganglioside IV3NeuAc,II3NeuAc-GgOse4Cer (GD1a) was strikingly expressed, in addition to GM1b and GD1 alpha that were already present in the parental cells. In spite of various IL-3-secreting capabilities, all transfectants investigated have exhibited the same ganglioside patterns and expressed GD1a. Furthermore, the appearance of GD1a was a consequence of the up-regulation of a single glycosyltransferase, CMP-NeuAc:lactosylceramide alpha 2-->3-sialytransferase (GM3 synthase). Activities of the other downstream glycosyltransferases that were involved in GD1a synthesis were not significantly different between the parental and the transfected cells. According to these data, the progression of tumor stage by the acquisition of autonomous cell growth ability after IL-3 gene transfection resulted in dramatic changes in cell surface gangliosides and their biosynthetic pathways. GD1a could be considered as an IL-3-associated ganglioside and was expressed in a tight connection with a single glycosyltransferase (GM3 synthase) up-regulation and with IL-3 expression in murine myelogenous leukemia cells.

Animals↗
PubMed1995

Luminal loss and site of restenosis after Palmaz-Schatz coronary stent implantation.

Restenosis has frequently been observed at the articulation of the Palmaz-Schatz stent. However, the precise mechanism for this remains poorly understood. We measured the luminal diameter in 5 segments within the stent in 67 lesions of 63 patients with successful stenting. Luminal diameter at all 5 sites was significantly reduced 6 months after stent implantation (3.2 +/- 0.5 vs 2.4 +/- 0.7 mm, p < 0.05). Angiographic restenosis rate was 18%. Restenosis involving the articulation was found in 75% of the lesions, and that involving the articulation or edges in 83%. The diameter at the articulation was significantly smaller both immediately (3.0 +/- 0.5 mm vs 3.3 +/- 0.5 mm, p < 0.05) and 6 months after (2.1 +/- 0.8 mm vs 2.5 +/- 0.7 mm, p < 0.05) stenting than the diameter of other stent segments. The loss index was significantly greater at the proximal and distal edges than at the bodies of the stent (0.98 vs 0.60, p < 0.05). The edges of the Palmaz-Schatz stent tend to dilate more than the body of the stent during normal inflation. Although this anchoring system protects against dislodgment or migration of the stent, it may cause more injury. The articulation has 2 anchoring edges within only a 1 mm diameter. Thus, restenosis at the articulation may be ascribed to residual stenosis, increased intimal proliferation due to more severe injury, and delayed late vessel remodeling from lack of mechanical support. These characteristics may be attributed to stent design, and design improvement of the articulation may lead to more favorable results after stent implantation.

Aged↗
PubMed1995

Comparison of intestinal absorption of vitamin K2 (menaquinone) homologues and their effects on blood coagulation in rats with hypoprothrombinaemia.

To examine the physiological activities of vitamin K2 (menaquinone, MK) homologues with different numbers of isoprene units, MK with 1-14 isoprene units and menadione (MK-0) were administered to rats with hypoprothrombinaemia, and the absorption, concentration in liver and ameliorating effect of these MK on hypoprothrombinaemia were compared. Hypoprothrombinaemia was induced by giving a vitamin K-deficient diet and warfarin (0.06 mg/kg body weight) for 8 days. Before MK treatment, the MK were undetectable in plasma and liver. At 6 hr after oral MK administration (0.1 mg/kg): MK was not detected in the plasma in rats treated with MK with 1, 2, 3 or more than 12 isoprene units; the MK level in the liver was increased but blood coagulation activity was not improved in rats treated with MK with 0, 9, 10 or 11 isoprene units; the MK level in the liver was increased and hypoprothrombinaemia was slightly improved in rats treated with MK with 7 or 8 isoprene units; and the MK level in the liver was increased and hypoprothrombinaemia was markedly improved in rats treated with MK with 4, 5 or 6 isoprene units. Almost identical results were observed 3 hr after intravenous injection of MK with 4, 5 or 6 isoprene units (10 nmol/kg). These findings suggest that the number of isoprene units of MK is an important factor in its absorption and incorporation into the liver and that the ameliorating effect of MK on hypoprothrombinaemia does not parallel their concentrations in the liver.

Administration, Oral↗
PubMed1995

Highly sensitive and rapid determination of theophylline, theobromine and caffeine in human plasma and urine by gradient capillary high-performance liquid chromatography-frit-fast atom bombardment mass spectrometry.

A sensitive and reliable analytical procedure has been established for the detection of theophylline (TH), theobromine (TB) and caffeine (CA) in human plasma and urine by gradient capillary high-performance liquid chromatography (HPLC)-frit-fast atom bombardment mass spectrometry (FAB-MS) (LC-frit-FAB-MS). Two capillary columns and a column-switching valve were used in this LC system to allow all of the sample injected to be introduced into the MS system. 7-Ethyltheophylline was used as the internal standard (I.S.). The xanthines in the specimen were extracted with an Extrelut column. The lowest detected amount was ca. 5 ng/ml using this method.

Caffeine↗
PubMed1995

Ras-independent and wortmannin-sensitive activation of glycogen synthase by insulin in Chinese hamster ovary cells.

Activation of glycogen synthase is one of the major metabolic events triggered by exposure of cells to insulin. The molecular mechanism by which insulin activates glycogen synthase was investigated. The possible role of Ras and mitogen-activated protein kinase cascade was investigated with a stable cell line, CHO-IR-C/S 46, that overexpresses insulin receptors and a catalytically inactive SH-PTP 2 protein phosphatase and in which insulin does not induce the formation of the Ras-GTP complex or the subsequently activation of the mitogen-activated protein kinase cascade. Insulin activated glycogen synthase in this cell line to a similar extent as in parental CHO-IR cells. The importance of heteromeric phosphoinositide (PI) 3-kinase in insulin activation of glycogen synthase was examined in a stable cell line, CHO-IR/delta p85, that overexpresses insulin receptors and a dominant negative mutant (delta p85) of the 85-kDa subunit of PI 3-kinase that lacks the binding site for the catalytic 110-kDa subunit. Insulin-dependent activation of PI-3 kinase and glucose transport, but not the formation of the Ras-GTP complex, are markedly attenuated in this cell line. In CHO-IR/delta p85 cells, insulin activated glycogen synthase to a similar extent as in parental CHO-IR cells. The failure of overproduction of the mutant (delta p85) protein to inhibit insulin activation of glycogen synthase was also confirmed by transient expression in Rat 1 cells with the use of a recombinant vaccinia virus. However, wortmannin abolished insulin activation of glycogen synthase in all cell lines. These data suggest that existence of a Ras-independent and wortmannin-sensitive pathway for activation of glycogen synthase by insulin.

Androstadienes↗
PubMed1995

Requirement for phosphoinositide 3-kinase in insulin-stimulated GLUT4 translocation in 3T3-L1 adipocytes.

Insulin stimulates glucose transport in muscle and fat cells by inducing the redistribution of a specific glucose transporter, GLUT4, from intracellular vesicles to the cell surface. Phosphoinositide (PI) 3-kinase has been implicated as a key intermediate in insulin-stimulated glucose transport by studies that have examined the effects of wortmannin and LY294002, which are thought to be specific inhibitors of this enzyme. However, the specificity of these compounds for PI 3-kinase has recently been questioned. Epidermal growth factor, which activates mitogen-activated protein kinase in mouse 3T3-L1 adipocytes, has now been shown to have no effect on PI 3-kinase activity or GLUT4 translocation in these cells. Furthermore, microinjection of a dominant negative mutant of the 85-kDa subunit of PI 3-kinase, which lacks a binding site for the catalytic 110-kDa subunit, inhibited GLUT4 translocation induced by insulin in 3T3-L1 adipocytes; microinjection of the wild-type protein had no effect. These observations indicate that PI 3-kinase is necessary for insulin-induced GLUT4 translocation and glucose transport in adipocytes.

3T3 Cells↗
PubMed1995

Phosphoinositide 3-kinase as an upstream regulator of the small GTP-binding protein Rac in the insulin signaling of membrane ruffling.

Membrane ruffling and the closely linked response of fluid-phase pinocytosis were investigated in Chinese hamster ovary cells that stably overexpress the human insulin receptor and a mutant 85-kDa subunit of phosphoinositide (PI) 3-kinase (delta p85) that lacks a binding site for the catalytic 110-kDa subunit of this enzyme. Both membrane ruffling and pinocytosis induced by insulin were markedly impaired in these cells. Microinjection of Rac, a Ras-related small GTP-binding protein, induced membrane ruffling in human epidermoid carcinoma KB cells, and this effect of Rac was not blocked by coinjection of delta p85 or by exposure of cells to wortmannin, a specific PI 3-kinase inhibitor. These results suggest that PI 3-kinase is essential not only for insulin-stimulated membrane ruffling but also for pinocytosis, and that PI 3-kinase possibly functions upstream of Rac in the signal transduction pathway.

Animals↗
PubMed1995

Normal activation of p70 S6 kinase by insulin in cells overexpressing dominant negative 85kD subunit of phosphoinositide 3-kinase.

The role of heteromeric phosphoinositide (PI) 3-kinase activity in insulin signal transduction was studied by investigating the effects of (i) overexpression of a dominant negative mutant p85 (delta p85) that lacks the binding site for p110 (delta p85-overexpressing cells) and (ii) inhibition of PI 3-kinase activity by wortmannin (wortmannin-treated cells). The insulin-induced association of PI 3-kinase activity with insulin receptor sustrate-1 (IRS-1) was inhibited in both wortmannin-treated cells and delta p85-overexpressing cells. However, whereas insulin-induced activation of p70 S6 kinase was completely abolished in wortmannin-treated cells, it appeared normal in delta p85-overexpressing cells. These results raise the possibility that a wortmannin-sensitive pathway independent of heteromeric PI 3-kinase is involved in the activation of p70 S6 kinase by insulin.

Amino Acid Sequence↗
PubMed1995

Effect of continuous positive airway pressure on intrathoracic and left ventricular transmural pressures in patients with congestive heart failure.

BACKGROUND: Continuous positive airway pressure (CPAP) can improve cardiac function in patients with congestive heart failure (CHF). We hypothesized that this effect might be related to CPAP-induced increases in intrathoracic pressure, which would reduce left ventricular transmural pressure (LVPtm) during systole, thereby decreasing left ventricular afterload. METHODS AND RESULTS: The effect of graduated CPAP from 0 to 10 cm H2O on the above variables was examined over a 75-minute period and compared with a 75-minute time control period without CPAP in two groups of subjects: 15 patients with CHF and 9 healthy subjects. Intrathoracic pressure was estimated from esophageal pressure (Pes), and systolic LVPtm, a determinant of left ventricular afterload, was assessed by subtracting Pes during systole from systolic blood pressure. Cardiac index (CI) was assessed by Doppler echocardiography. At baseline, inspiratory Pes amplitude, which reflects inspiratory muscle force generation, was greater in the patients with CHF than in the healthy group (9.9 +/- 0.8 versus 5.5 +/- 0.4 mm Hg, P < .001). In addition, systolic Pes, which represents the relative contribution of intrathoracic pressure to LVPtm, was more negative in the patients with CHF than in the healthy group (-4.1 +/- 0.3 versus -2.2 +/- 0.1 mm Hg, P < .001). While on CPAP of 10 cm H2O, inspiratory Pes amplitude decreased and systolic Pes increased significantly in the group with CHF (from 11.1 +/- 1.1 to 7.5 +/- 1.1 mm Hg, P < .025 and from -4.7 +/- 0.6 to 0.6 +/- 0.6 mm Hg, P < .001, respectively), but CPAP had no effect on these variables in the healthy subjects. Compared with the equivalent time control period, Pes amplitude x respiratory rate decreased significantly while on CPAP in both the group with CHF (from 188 +/- 22 to 112 +/- 17 mm Hg x breaths per minute, P < .005) and the healthy group (from 82 +/- 8 to 60 +/- 6 mm Hg x breaths per minute, P < .05). Compared with time control, systolic LVPtm decreased significantly while on CPAP, from 116.0 +/- 5.3 to 110.3 +/- 4.5 mm Hg (P < .025) in the group with CHF, but did not change in the healthy group. Moreover, systolic LVPtm x heart rate decreased significantly in the group with CHF (from 80.55 +/- 5.27 to 71.83 +/- 4.73 mm Hg x beats per minute/100, P < .005) but not in the healthy group. CI decreased significantly while on CPAP in the healthy group (P < .025) but did not change in the group with CHF. CONCLUSIONS: In patients with CHF, the inspiratory muscles generate greater force per breath and systolic Pes contributes more to LVPtm than in healthy subjects. By increasing intrathoracic pressure in patients with CHF, CPAP unloaded inspiratory muscles and reduced left ventricular afterload without compromising CI.

Adult↗
PubMed1995

Intracoronary stenting of a coronary occlusion resulting from an aortic dissection.

Acute myocardial infarction secondary to aortic dissection may occur due to compression of the coronary arteries by a hematoma or extension of the dissection into the coronary arterial wall. We report a patient with this condition who was successfully treated by Palmaz-Schatz stenting, providing an alternative to thrombolysis or angioplasty.

Aortic Dissection↗
PubMed1995

Detection of (1-3)-beta-D-glucan in a rat model of aspergillosis.

The G test containing factor G, fractioned from the Limulus lysate, was used to detect (1-3)-beta-D-glucan in a rat model of aspergillosis. Aspergillus fumigatus strain MF-13, 1 x 10(4) conidia, were inoculated transtracheally into rats treated with cortisone acetate (100 mg/kg) and fed a low-protein (8%) diet. Increased serum (1-3)-beta-D-glucan was found on the sixth day after inoculation in concentrations of 370 +/- 178 pg/ml (mean +/- SD) in untreated controls, and 154 +/- 43 pg/ml in rats treated with 0.5 mg/kg of amphotericin B. On day 11 (1-3)-beta-D-glucan concentrations were 2,590 +/- 2,940 pg/ml and 448 +/- 442 pg/ml, respectively. The elevation in levels of (1-3)-beta-D-glucan increased in correlation with the elevation of galactomannan antigen titers; (1-3)-beta-D-glucan is thus measurable during experimental aspergillosis in rats.

Amphotericin B↗
PubMed1995

(1-->3)-beta-D-glucan in culture fluid of fungi activates factor G, a limulus coagulation factor.

Two well-known polysaccharides, (1-->3)-beta-D-glucan and mannan, are major structural components of the fungus cell wall. The G test is a direct method to measure (1-->3)-beta-D-glucan using a (1-->3)-beta-D-glucan-sensitive component, factor G, fractionated from the limulus lysate. The concentration of (1-->3)-beta-D-glucan in culture supernatants of Candida albicans increased to 1,390.0 pg/ml at 24 hours. The concentration of mannan also increased parallel with fungal growth. However, after digestion of supernatants with endo-(1-->3)-beta-D-glucanase, the reactivity to factor G disappeared, although titers of antimannan monoclonal antibody-based latex agglutination were unchanged. Our study demonstrated that cell suspensions of both C. albicans and Cryptoccocus neoformans activated the limulus factor G, and that not only the conidia form but also the filamentous form of Aspergillus fumigatus reacted with factor G. Various Candida spp. (C. paraspilosis, C. glabrata, C. tropicalis, C. krusei), Saccharomyces cerevisiae, Rhodotorula rubra, Trichosporon beigelii, and A. fumigatus released soluble (1-->3)-beta-D-glucan into their culture supernatants, but C. neoformans and Cunninghamella bertholletiae showed only a small reaction to the G test during their culture. Our results indicate that the G test is a good method for serodiagnosis of deep mycosis and also as a screening tool for contamination of medical devices, drugs, and experimental materials with (1 --> 3)-beta-D-glucan.

Agglutination↗
PubMed1995

DNA aneuploidy in a case of rectosigmoid adenocarcinoma complicated by ulcerative colitis.

A case of Borrmann type IV colorectal adenocarcinoma detected as a complication of long-standing ulcerative colitis is reported. Barium enema and colonoscopy disclosed a stenotic area associated with a tumoral mass and a flat elevated lesion in the rectosigmoid region and a submucosal tumor-like lesion in the rectum. Total colectomy was performed and histological studies demonstrated a moderately differentiated adenocarcinoma accompanied by high- and low-grade dysplasia. DNA ploidy pattern analysis showed aneuploidy in the adenocarcinoma and high-grade dysplasia, but diploidy in the normal and atrophic mucosa and in low-grade dysplasia. DNA aneuploid content was associated with the presence of colorectal carcinoma complicating ulcerative colitis, indicating that DNA content studies should be included in screening programs to detect early colorectal carcinoma following this disease, as a complementary study to histological assessment.

Adenocarcinoma↗