Biomedical subjects

K Hirata

Publications and source records attributed to K Hirata.

At least 127 records · Page 7Linked to original sources

PubMed2001

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market.

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GC-MS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1 mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl anti BFDGE.HCl.H2O at a level of 1.5 mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.

Benzhydryl Compounds↗

PubMed2001

Age-associated increase of 8-hydroxydeoxyguanosine in human colorectal tissue DNA.

To clarify the role of oxidative stress in aging of colorectal tissue, we analyzed the 8-hydroxydeoxyguanosine (8-OH-dG) levels in colorectal biopsy samples from normal tissue of patients with either colorectal cancer (n = 15) or benign colorectal polyps (n = 40). An age-associated increase of 8-OH-dG was observed (p =.002), although the 8-OH-dG levels were not significantly different between the patients with cancer and those with polyps. These results suggest an increased level of 8-OH-dG formation in human colorectal tissue with age.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2001

The relationship between plasma concentration of mature adrenomedullin and jugular venous oxygen saturation during and after cardiopulmonary bypass.

UNLABELLED: Adrenomedullin (AM), a vasodilatory peptide, increases during cardiac surgery. However, the physiological role of AM during cardiac surgery remains unclear. AM dilates cerebral arterioles and increases cerebral blood flow in rats. Therefore, we investigated whether AM is related to cerebral oxygen balance during cardiac surgery. In nine patients undergoing coronary artery bypass grafts, plasma concentrations of mature AM from the radial artery (mAMa) and jugular bulb (mAMj) were measured, and jugular venous oxygen saturation was obtained before surgery (baseline), before aortic cross-clamp (preclamp), after aortic declamp (postclamp), and 20 min after weaning from the cardiopulmonary bypass (post-CPB). Plasma concentrations of mAMa and mAMj were significantly increased at postclamp (P < 0.01 for both) and post-CPB (P < 0.01 for both) compared with baseline values. SjO(2) correlated with plasma mAMj concentrations at preclamp (r = 0.79, P < 0.01), postclamp (r = 0.71, P < 0.05), and post-CPB (r = 0.72, P < 0.05), as well as with mAMa concentrations at preclamp (r = 0.79, P < 0.01) and postclamp (r = 0.72, P < 0.05). This suggests a relationship between AM and cerebral oxygen balance during cardiac surgery. IMPLICATIONS: Plasma concentrations of mature-form adrenomedullin, a vasodilatory peptide, was correlated with jugular venous oxygen saturation during cardiac surgery. This suggests a relationship between adrenomedullin and cerebral oxygen balance during cardiac surgery.

Adrenomedullin↗

PubMed2001

A calcium channel blocker, benidipine, inhibits intimal thickening in the carotid artery of mice by increasing nitric oxide production.

OBJECTIVE: Recent studies suggest that several calcium channel blockers exert their protective effects against vascular disorders by increasing nitric oxide (NO) production from the endothelium. The purpose of this study was to clarify the effects of a long-lasting calcium channel blocker, benidipine, on vascular remodeling. METHODS: The left common carotid arteries of mice were completely ligated just proximal to the carotid bifurcation. Treatment with benidipine (3 mg/kg per day) or vehicle was started 1 week before the carotid ligation, and continued throughout the experiments. Four weeks after the carotid ligation, these mice were killed and vascular remodeling was analyzed. Moreover, NO production and endothelial NO synthase (eNOS) expression were assessed. RESULTS: At 4 weeks after ligation, the neointimal area in the vehicle-treated mice was 39,400 +/- 4,900 microm2 (n = 8), whereas that in the drug-treated mice was reduced to 18,300 +/- 3,800 microm2 (n = 10). Consequently, the luminal area was 35% larger in the drug-treated mice. Benidipine increased the basal as well as agonist-induced NO production from the endothelium, detected by Griess method or NOx analyzer. Endothelial NOS expression in vessels of the drug-treated mice was increased compared with that of the vehicle-treated mice. CONCLUSION: Our data provide evidence that benidipine increases NO production via increment of eNOS protein in vessels and prevents intimal thickening in mice. These results show the possibility of benidipine as a protective tool against vascular remodeling independent of its effect on blood pressure.

Animals↗

PubMed2001

Congenital arteriovenous malformation of the pancreas: its diagnostic features on images.

To analyze diagnostic features on images of congenital arteriovenous malformation (AVM) of the pancreas, we analyzed the diagnostic findings in six patients with the disease, using gray-scale ultrasonography (US), color Doppler US, computed tomography, and angiography and analyzed previously reported cases. AVM characteristic findings on images were multiple, small hypoechoic nodules on US, mosaic appearance of the lesion and pulsatile wave form in the portal vein on color Doppler US, conglomerated small nodular enhancement of the lesion and early appearance of the portal vein on CT, and a racemose network and early appearance of the portal vein on angiography. Five of the six patients underwent surgery, and all resected specimens were histologically found to be AVMs of the pancreas; however, one with developed portal hypertension at surgery died of repeated bleeding from esophageal varices. From analysis of total of 35 cases including our six cases, a mosaic appearance of the lesion was found in 100% and a pulsatile wave form in the portal vein in 77.8% on color Doppler US. Color Doppler US is noninvasive and useful for detecting congenital AVM of the pancreas at an early stage, preventing the portal hypertension causing esophageal varices and their rupture.

Adult↗

PubMed2001

A new peritoneal dissemination model established from the human pancreatic cancer cell line.

We established a new cell line, HPC-3P4a, with high peritoneal disseminated potential in nude mice. HPC-3P4a was derived from a human pancreatic carcinoma cell line (HPC-3) that had low capacity for peritoneal dissemination. HPC-3P4a developed peritoneal dissemination in 10 of 11 (90.9%) cases, whereas parental HPC-3 developed peritoneal dissemination in one of six (16.7%) cases. The metastatic foci in the peritoneum showed essentially the same histologic appearance of parental involvement. The tumorigenicity, motility, and adhesive activity of HPC-3P4a to the extracellular matrix were stronger than were those of the HPC-3. In FACS analysis, HPC-3P4a significantly increased the expression of alpha6 and alpha(v)beta5 integrins, while it decreased alpha2 integrin, hCD44H, and hCD44v 10, as compared with HPC-3. The VEGF production of HPC-3P4a was significantly lower than that of HPC-3. Analysis of gene macroarrays showed a variety of cytokines, interleukin, and other immunomodulatory, and their receptors were up-regulated and down-regulated on an mRNA level in HPC-3P4a cells, compared with HPC-3 cells. Intrasplenic injection of HPC-3P4a produced no liver metastasis. We named our original highly liver metastatic cell line HPC-3H4 (previously reported). This HPC-3H4 cell was established by repeated intrasplenic injection from parental cell HPC-3; thus, it developed high liver metastasis. Moreover, HPC-3H4 developed peritoneal dissemination by intra-abdominal injection. In contrast, HPC-3P4a did not develop liver metastasis by intrasplenic injection. These findings are very interesting and might suggest that the process of hematogenous metastasis differed from that of peritoneal dissemination. Thus, this cell line may be useful for investigating the mechanism of peritoneal dissemination in human pancreatic cancer.

Adenocarcinoma↗

PubMed2001

A novel experimental mouse model of peritoneal dissemination of human gastric cancer cells: analysis of the mechanism of peritoneal dissemination using cDNA macroarrays.

We established a new cell line, NUGC-3P4T, with high peritoneal metastatic disseminating potential in nude mice. NUGC-3P4T cells were derived from the human gastric carcinoma line NUGC-3, which has low capacity for peritoneal dissemination. NUGC-3P4T cells developed peritoneal dissemination in 10 / 10 (100%) mice, whereas the parental NUGC-3 cells developed dissemination in 1 / 5 (20.0%) mice. The metastatic foci in the peritoneum showed essentially the same histological appearance as those induced by parental cells. The tumorigenicity, the motile activity and the adhesive activity to the laminin of NUGC-3P4T cells were stronger than those of NUGC-3 cells. Production of IL-8 was significantly higher in NUGC-3P4T than in NUGC-3. cDNA macroarrays analysis showed that a variety of cytokines, interleukins, and other immunomodulators and their receptors were up- or down-regulated at the mRNA level in NUGC-3P4T cells, compared with NUGC-3 cells. Thus, this unique cell line and in vivo model might be useful to study the biology of peritoneal dissemination of human gastric cancer.

Animals↗

PubMed2001

Anti-GQ1b IgG antibody syndrome: clinical and immunological range.

OBJECTIVES: To clarify the nosological relation among Miller Fisher syndrome (MFS), Guillain-Barré syndrome (GBS) with ophthalmoplegia, Bickerstaff's brain stem encephalitis (BBE), and acute ophthalmoparesis without ataxia. Serum samples from patients with each condition often have anti-GQ1b IgG antibody. METHODS: Information on antecedent illness, initial symptoms, neurological signs during the illness, and CSF findings were reviewed in 194 patients with anti-GQ1b IgG. It was determined whether overlapping MFS and GBS (MFS/GBS), as well as overlapping BBE and GBS (BBE/GBS), is explained by the combined action of anti-GQ1b IgG and anti-GM1 or anti-GD1a IgG, serological markers of GBS. RESULTS: Based on the diagnostic criteria, all the patients with acute ophthalmoparesis, MFS, MFS/GBS, BBE/GBS, and BBE had external ophthalmoplegia; all the patients with MFS, MFS/GBS, or GBS had hyporeflexia or areflexia; and all those with MFS and BBE showed ataxia. Tendon reflexes were decreased or absent in 91% of those with BBE/GBS, 67% of those with BBE, and 53% of those with acute ophthalmoparesis. Ataxia was present in 68% of the patients with MFS/GBS and 45% of those with BBE/GBS. Antecedent illness caused by upper respiratory tract infection had occurred in 60% to 80% of these patients, and CSF albuminocytological dissociation in 25% to 75%. Anti-GM1 or anti-GD1a IgG was present in 50% of those with GBS, 35% of those with MFS/GBS, 27% of those with BBE/GBS, 16% of those with MFS, and 8% of those with BBE. CONCLUSIONS: These findings together with the common autoantibody (anti-GQ1b IgG) suggest that a common autoimmune mechanism functions in the pathogenesis of these illnesses. In a larger study, it was confirmed clinically that MFS, GBS, BBE, and acute ophthalmoparesis are closely related, forming a continuous range. This is supported by the immunological findings. The term "anti-GQ1b IgG antibody syndrome" is not intended to be used as a clinical diagnosis, but recognition of this syndrome is useful for understanding the aetiological relation among the various illnesses and for introducing the established treatments of GBS for use with other conditions.

Adolescent↗

PubMed2001

Comparative study of preceding Campylobacter jejuni infection in Guillain-Barré syndrome in Japan and The Netherlands.

A comparative study was made in Japan and The Netherlands of the presence of preceding Campylobacter jejuni infections in Guillain-Barré syndrome (GBS). It was conducted in two laboratories using different serological criteria. The Japanese results showed no significant difference in the frequency of C jejuni infection between the Japanese (17/88, 19%) and Dutch (21/132, 16%) patients with GBS. The Dutch investigation showed a higher frequency in Dutch patients (45/132; 34%) than in Japanese patients(20/88; 23%), but the difference did not reach significance. Although the frequencies of preceding C jejuni infection have been reported to be higher in Asian countries than in western countries, the findings of this collaborative study show that the incidence of antecedent C jejuni infection in GBS in Japan is not higher than in The Netherlands and that serological assays vary considerably between laboratories.

Campylobacter Infections↗

PubMed2001

Range of cross reactivity of anti-GM1 IgG antibody in Guillain-Barré syndrome.

The cross reactivity of anti-GM1 IgG antibody with various gangliosides and asialo-GM1 in serum samples from 27 patients with Guillain-Barré syndrome was investigated. An enzyme linked immunosorbent assay (ELISA) absorption study showed that anti-GM1 IgG antibody cross reacted with asialo-GM1 in 52% of the patients, GM1b in 41%, GD1b in 22%, and GalNAc-GD1a in 19%, and that it did not cross react with GM2, GT1b, or GQ1b. The antibody that cross reacted with GD1b was associated with a high frequency of cranial nerve involvement and negative Campylobacter jejuni serology. Anti-GM1 IgG antibody has a broad range of cross reactivity which may contribute to various clinical variations of Guillain-Barré syndrome.

Adult↗

PubMed2001

Regulation of tyrosine phosphorylation of PYK2 in vascular endothelial cells by lysophosphatidylcholine.

Lysophosphatidylcholine (LPC), a component of oxidized low-density lipoprotein, exerts various biological effects on vascular endothelial cells. However, the intracellular signaling of LPC is poorly understood. In this study, we investigated the involvement of proline-rich tyrosine kinase (PYK2) in LPC signaling in cultured bovine aortic endothelial cells by immunoprecipitation and Western blotting assays. Treatment of cells with LPC promoted a rapid increase in tyrosine phosphorylation of PYK2. LPC-stimulated PYK2 phosphorylation was inhibited by calcium chelators, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester, EGTA, protein kinase C (PKC) inhibitor, GF-109203X, or PKC depletion by phorbol esters. PYK2 phosphorylation was inhibited by treatment with cytochalasin D but with neither botulinum C3 transferase nor overexpression of a dominant negative mutant of Rho A. LPC stimulated the association of Shc with PYK2, Shc tyrosine phosphorylation, and Grb2 binding to Shc and induced Ras activation. These results provide evidence that 1) LPC tyrosine phosphorylates PYK2 by calcium- and PKC-dependent mechanisms, 2) the intact cytoskeleton is required for LPC-stimulated PYK2 phosphorylation, and 3) LPC-activated Ras via the PYK2/Shc/Grb2 signaling.

ADP Ribose Transferases↗

PubMed2001

Endothelial NO synthase overexpression inhibits lesion formation in mouse model of vascular remodeling.

NO produced by endothelial NO synthase (eNOS) plays important roles in the regulation of vascular tone and structure. The purpose of this study was to clarify the role of eNOS-derived NO on vascular remodeling by use of eNOS-transgenic (eNOS-Tg) mice. The common carotid artery was ligated just proximal to the carotid bifurcation. Four weeks later, the proximal carotid artery of the ligation site was histologically examined. In this vascular remodeling model, the endothelium remains uninjured, but neointimal and medial thickening occurs in combination with a reduction in vascular diameter at the proximal portion of the ligation. At 4 weeks after ligation, the respective neointimal and medial areas in wild-type mice were 17 200+/-1100 and 24 300+/-1500 microm(2), whereas both were reduced to 8000+/-1900 (P:<0.01) and 18 400+/-700 microm(2) (P:<0.01) in eNOS-Tg mice (n=8). Total vascular area was not different between the 2 genotypes. N:(G)-Nitro-L-arginine methyl ester treatment increased neointimal and medial areas to the same extent in both genotypes. Leukocyte infiltration was observed in the luminal side of the vessel, but the number of infiltrating cells was significantly attenuated in eNOS-Tg mice compared with wild-type mice. This reduction of leukocyte infiltration in eNOS-Tg mice was associated with reduced expressions of intracellular adhesion molecule-1 and vascular cellular adhesion molecule-1 on the endothelium. In conclusion, chronic eNOS overexpression in the endothelium reduced leukocyte infiltration and inhibited neointimal formation and medial thickening. Our data provide the evidence for the regulatory role of NO from the endothelium on vascular structure integrity.

Animals↗

PubMed2001

Side chain-dependent binding of antitumor indoloquinoxaline derivatives to DNA: comparative spectroscopic and viscometric measurements.

NCA0424 (1) and its side chain positional isomer, NCA0465 (2), are indoloquinoxaline derivatives with potent antitumor activity. To investigate the effect of side chain position for binding with DNA, the interactions of 2 with various B-form DNAs were studied by spectroscopic (circular dichroism (CD), fluorescence and UV) and viscosity measurements and were compared with those of 1. The binding preference for the base sequence was different in each case. The CD spectra showed that 2 formed an asymmetric binding of indoloquinoxaline ring with adenine in DNA, whereas such a base selectivity was not found with 1. The binding features are discussed based on association constants and thermodynamic parameters, indicating the importance of the side chain position for binding specificity for DNA.

DNA↗

PubMed2001

Relationship between doppler-derived left ventricular diastolic function and exercise capacity in patients with myocardial infarction.

Doppler echocardiographic indices of left ventricular (LV) diastolic function are widely used to evaluate the cardiac function of patients with cardiac disease. However, there have been few reports about the relationship between Doppler indices and exercise capacity and so 44 patients with myocardial infarction were investigated by cardiopulmonary exercise testing and 2-D and Doppler echocardiography. Diastolic performance was assessed using Doppler transmitral flow velocity and pulmonary venous flow velocity. The ratio of peak E wave velocity and peak A wave velocity (E/A) correlated with peak oxygen consumption (peak Vo2) (R=0.72), and there was a negative correlation between the deceleration time of E velocity (Dct) and peak Vo2 or anaerobic threshold (AT) (R=-0.65, -0.62, respectively). The ratio of peak S wave velocity and peak D wave velocity (S/D) negatively correlated with peak Vo2 (R=-0.58). Left ventricular ejection fraction did not correlate to exercise capacity. These results suggest that the Doppler echocardiographic indices of LV diastolic function correlate with exercise capacity in patients with mild cardiac dysfunction.

Aged↗

PubMed2001

Local implantation of autologous bone marrow cells for therapeutic angiogenesis in patients with ischemic heart disease: clinical trial and preliminary results.

A new therapy for severe ischemic heart disease has been developed; therapeutic angiogenesis induced by the local implantation of autologous bone marrow cells (BMC). After confirming that no detrimental changes were induced by this treatment in a canine heart model, a clinical trial was commenced in 1999. Thus far, 5 patients have been given this new treatment concomitant with coronary artery bypass grafting and all have been followed up for at least 1 year. Autologous BMC were implanted into the ungraftable area and postoperative cardiac scintigraphy showed specific improvement in coronary perfusion in 3 of the 5 patients. Postoperative chest radiography, electrocardiography, echocardiography and blood tests did not reveal any detrimental changes. In conclusion, this new therapy appears to be safe and could provide a treatment option for patients with otherwise untreatable ischemic heart disease.

Aged↗

PubMed2001

Large vessel arteritis in relapsing polychondritis.

A healthy 58-year-old woman presented with recurrent swelling and pain of the nose and both auricules. Bruits were heard over both carotid arteries. Magnetic resonance angiography revealed stenosis of both internal carotid arteries. Relapsing polychondritis was diagnosed. These symptoms improved after treatment with prednisolone and azathioprine. Although relapsing polychondritis is sometimes associated with systemic vasculitis, large vessel arteritis is rare and can negatively affect prognosis. We conclude that the detection of systemic vascular lesions, including those involving the central nervous system, can play an important role in the diagnosis of relapsing polychondritis and that early treatment is essential for a good outcome.

Arteritis↗

PubMed2001

H2 production from algal biomass by a mixed culture of Rhodobium marinum A-501 and Lactobacillus amylovorus.

To produce hydrogen from starch accumulated in an algal biomass, we used a mixed culture of the lactic acid bacterium, Lactobacillus amylovorus, and the photosynthetic bacterium, Rhodobium marinum A-501. In this system L. amylovorus, which possesses amylase activity, utilized algal starch for lactic acid production, and R. marinum A-501 produced hydrogen in the presence of light using lactic acid as an electron donor. Algal starch accumulated in the marine green alga Dunaliella tertiolecta, and the freshwater green alga Chlamydomonas reinhardtii, was more suitable for lactic acid fermentation by L. amylovorus than an authentic starch sample. Consequently, the yields of hydrogen obtained from starch contained in D. tertiolecta and C. reinhardtii were 61% and 52%, respectively, in the mixed culture of L. amylovorus and R. marinum A-501. These values were markedly superior to those obtained using a mixed culture of Vibrio fluvialis T-522 and R. marinum A-501 described previously. The yield and production rate of hydrogen by R. marinum A-501 from the lactic acid fermentates were higher than from authentic lactic acid, suggesting that the fermentates contain a factor(s) which promotes H2 production by this bacterium.

Journal Article↗

PubMed2001

Strong induction of phytochelatin synthesis by zinc in marine green alga, Dunaliella tertiolecta.

Synthesis of phytochelatins (PCs), heavy-metal-sequestering peptides, in the marine green alga, Dunaliella tertiolecta, was evaluated under various conditions of exposure to heavy metals. To investigate the effect of heavy metals on both PC synthesis and their upstream biosynthetic reactions, an ion-pair-HPLC system was developed in this study, by which PCs and their biosynthetic intermediates, cysteine (Cys), gamma-glutamylcysteine (gammaEC) and glutathione (GSH), could be determined simultaneously with high sensitivity. When the cells were exposed to Zn2+, the level of PCs was maximal at 200 microM and significantly higher than that obtained after exposure to 400 microM Cd2+, which is the strongest inducer of PC synthesis in higher plants in vivo and in vitro as well as in microalgae. The predominant PC subtype was PC4, followed by PC3 and PC5, whereas PC2, which is generally abundant in higher plants, has the lowest level among PC2 to PC5. These results suggest that the characteristics of PC synthase in D. tertiolecta including the requirement of heavy metals for its catalysis and substrate specificity towards GSH and PC(n) are considerably different from those in higher plants and other algae. While PC synthesis proceeded in the heavy-metal-treated cells, the level of GSH did not appreciably change. To maintain the same size of the GSH pool, GSH must be newly synthesized to balance the amount consumed for PC synthesis.

Journal Article↗