Biomedical subjects

Hiroaki Okabe

Publications and source records attributed to Hiroaki Okabe.

At least 19 recordsLinked to original sources

PubMed2005

Role of extracellular superoxide dismutase in patients under maintenance hemodialysis.

BACKGROUND: It has been well documented that free radical injury is involved in the progression of chronic renal failure. Extracellular superoxide dismutase (EC-SOD), localized on the endothelial cell surface, plays an important role in reducing oxidative stress especially in the vessels by binding to the endothelial cell surface via the heparin-binding domain. Although EC-SOD Arg213Gly, which cannot bind on endothelial cells, has been considered a polymorphism, the effect of EC-SOD on hemodialysis patients has not been well examined. METHODS: In 178 hemodialysis patients, the following examinations were performed. EC-SOD Arg213Gly was examined by polymerase chain reaction (PCR)-induced mutation restriction analysis (PCR-IMRA). As indexes of atherosclerosis, the annual progression in intima-media thickness (DeltaIMT), plaque score, pulse wave velocity (PWV) and plasma-oxidized low-density lipoprotein (OxLDL) values were examined. RESULTS: PCR-IMRA revealed that 20 of 178 patients possessed the mutation (11.2%), and the incidence was about twice as high as that in a previously reported Japanese population. Although there were no statistical differences in plaque score and PWV with and without EC-SOD Arg213Gly, DeltaIMT and plasma OxLDL values in patients with EC-SOD Arg213Gly were significantly higher than those in patients without the mutation. CONCLUSION: EC-SOD Arg213Gly is an accelerating factor for the progression of renal failure and atherosclerosis.

Adult↗

PubMed2005

Measurement of total and differential white blood cell counts in synovial fluid by means of an automated hematology analyzer.

We developed a rapid and accurate method for quantifying total and differential white blood cell (WBC) counts by pretreating synovial fluid with hyaluronidase and using an automated hematology analyzer. Forty-seven samples of synovial fluid that had been placed in blood-collection tubes containing ethylenediamine- N,N,N',N' -tetraacetic acid as an anticoagulant were treated with hyaluronidase at 37 degrees C for 10 minutes, and then the total and differential WBC counts were determined by means of the automated hematology analyzer. Results were compared with those achieved by traditional manual counting methods. For the automated method, the coefficient of variation values for within-run precision of the WBC count were 5.27%, 3.56%, and 3.01% at 0.54, 1.12, and 2.05 x 10(9) /L, respectively; the run-to-run coefficient of variation values was less than 10.0%. The total and differential WBC counts obtained by this automated method showed good correlation with those obtained by the hemocytometer method ( r = .998; P < .0001; regression formula, y = 0.986 x - 0.072). Bland-Altman plots indicated no significant discrepancy between the methods. Our evaluation supports the use of this automated hematology analyzer method to measure total and differential WBC counts, which should aid clinical diagnosis.

Arthritis, Infectious↗

PubMed2005

Inhibition of lipopolysaccharide-induced tissue factor expression in monocytes by urinary trypsin inhibitor in vitro and in vivo.

Tissue factor (TF) plays a critical role in the pathogenesis of disseminated intravascular coagulation (DIC) observed in patients with septic shock. Urinary trypsin inhibitor (UTI), a multivalent protease inhibitor, is currently used for treatment of patients with septic shock. This study was undertaken to determine whether UTI reduces LPS-induced coagulation abnormalities by inhibiting lipopolysaccharide (LPS)-induced expression of TF by monocytes. UTI inhibited LPS-induced increases in both TF activities and TF mRNA expression in monocytes without affecting the viability. Although activation of nuclear factor-kappaB (NF-kappaB), activator protein-1 (AP-1) and extracellular signal-regulated kinase (ERK)1/2 were shown to be critically involved in LPS-induced increases in TF activities in isolated monocytes, UTI inhibited phosphorylation of ERK1/2 and decreased expression of early growth response factor-1 (Egr-1) induced by LPS without affecting the activation of NF-kappaB and AP-1. UTI inhibited both the expression of TF mRNA in whole blood, increases in TF activities in mononuclear cells, and increases in serum levels of fibrin and fibrinogen degradation products (E) in rats given LPS without affecting the number of monocytes in the peripheral blood. Taken together these results strongly suggested that UTI might reduce LPS-induced coagulation abnormalities in rats by inhibiting TF expression in monocytes through inhibition of Egr-1 expression.

Animals↗

PubMed2005

[Pitfalls in homogeneous assays for HDL-c and LDL-c in serum].

Between 1994 and 2004, homogenous assays for HDL-C and LDL-C based on different determination principles were developed to replace complicated conventional precipitation methods. Nowadays, most laboratories employ homogenous assays. However, due to differences in principles and reactivity, measurements made by different assays do not necessarily match in some cases. HDL-C determinations may vary depending on duration and conditions of serum storage for the CDC-DCM and the homogenous assay methods, due to their different principles of determination. In patients with cholestasis, apoE-rich HDL, Lp-X and Lp-Y are occasionally observed. In these cases, the reactivity of homogenous assays for HDL-C varies markedly among the manufacturers. Furthermore, because the specific gravities of Lp-X and Lp-Y are comparable to that of LDL, these lipoproteins are grouped as LDL by ultracentrifugation, and this is a source of confusion in clinical settings. The American CDC assesses the accuracy of cholesterol assays by the BQ method, which measures the total of IDL, the narrowly-defined LDL, and Lp(a). However, of the various homogenous assays for LDL-C, reactivities to IDL and Lp (a) differ, and as a result, it is possible that type III hyperlipidemia characterized by increased IDL may be misdiagnosed.

Arteriosclerosis↗

PubMed2005

[My Kumamoto life of 19 years].

In this paper titled "My Kumamoto Life of 19 Years; The Travel for Times", the memorial lecture on my retirement from Kumamoto National University Corporation Integrated Medical and Pharmaceutical Sciences, Department of Biomedical Informatics (Chairman) is summarized. As they say "Time flies", time extends from seconds to years. The lecture includes a summary of my short term research and long term studies, such as age-dependant and gene-related changes in ageing over 5 or more years in the healthy elderly. Short-term study mostly involved of newly evaluated assay methods for important substances such as the second level in the cell life span in the variation of lipid metabolite of cardiovascular diseases based on atherosclerosis, Alzheimer disease, and their evaluation by homogeneous assay of HDL-C, LDL-C, enzymatic assay for choline relating metabolites, and lipoperoxide as the results of free radical reactions. The intermediate-term studies were mainly on the development of total laboratory automation (TLA) for the management of the laboratory of the university hospital. The hospital has various degrees of sophistication in its laboratory services. Technicians were allowed to transport specimens immediately by using an air-shooter system after drawing blood, from the emergency room to the central laboratory. Routine specimens could be measured within 30 min and the results could be automatically sent to the physician's office. It greatly minimized reporting errors, decreased the exposure to biohazards, reduced labor expense, improved operation efficiency, and shortened turnaround time. Moreover, for the outpatients and emergency laboratories, we constructed a robotic measuring system which was assembled into a sequential method for the analysis of chemistry, hematology and urinalysis specimens by using a polyarticular robot. The robot arm extends to a bar-coded tube, picking up and placing test tubes on a turn table of autoanalyzers for analysis without manpower. This is the first known effective unmanned procedure for assay in the world of laboratory medicine. Also, our research on pathological informatics was begun. Our laboratory had 7 themes; the study of the reference intervals in the elderly as one of strategy of standardization on laboratory data (Drs. Uji Y, Sugiuchi H), the study of the activation mechanism of ribosomal proteins by the functions of blood cells (Drs. Shibuya Y, Senba U), the evaluation of diagnostic methods in latent ailments by gene analysis (Dr. Ando Y), the evaluation of a highly sensitive method for disseminated intravascular coagulopathy (Okajima K), the study of the neogenesis of blood vessels by physical invasion (Uchiba M), the study of the deposition mechanism of amyloid proteins and evaluation of the diagnostic methods in the autonomic system(Drs. Ando Y, Nakamura M), and the study of the function of blood stem cells in blood transfusion services (Drs. Yamaguchi K, Yonemura M, Tsunemi M). Finally, my long term work also included research into the early diagnosis and prediction of latent ailments and the variation of serum proteins levels in the healthy aged. The conclusion was that the reference value of healthy populations and individuals (intra-personal) who had no combined ailments, in follow-up for 5 years, categorized by age, sex, and social conditions, gave a narrower range of variation than did large mixed populations (inter-personal), in laboratory tests and activity of daily living (ADL). Concerning the early diagnosis and prediction studies for the latent ailments in the aged, variations of serum protein levels in the healthy aged were classified into 3 types: serum proteins levels increased with advancing age (alphaAT, mainly acute phase reactant proteins), those that decreased with advancing age (albumin mainly transporting proteins) and proteins with no significant variation. The higher increase of the alpha1AT/beta2 III ratio in the healthy aged over 60 years old is suspected to create symptoms in the near future. The papers presented concerning ageing studies were presented at the APCCC Symposium (India, 2002) and the IFCC Symposium (Kyoto, 2002), and the TLA study was also presented at the Symposium of XX World Congress of Pathology and Laboratory Medicine (San Paulo Brazil 1999).

Clinical Laboratory Information Systems↗

PubMed2004

Urinary trypsin inhibitor reduces LPS-induced hypotension by suppressing tumor necrosis factor-alpha production through inhibition of Egr-1 expression.

Although urinary trypsin inhibitor (UTI) has been shown to inhibit tumor necrosis factor (TNF)-alpha- production, the detailed mechanism(s) remains unclear. This study was undertaken to elucidate the molecular mechanism(s) underlying this inhibitory effect in monocytes in vitro and in rats given lipopolysaccharide (LPS). TNF-alpha production by monocytes stimulated with LPS (100 ng/ml) was inhibited by UTI at concentrations higher than 100 U/ml. Expression of early growth response factor-1 (Egr-1) and phosphorylation of extracellular signal-regulated protein kinases 1/2 in monocytes stimulated with LPS were inhibited by UTI. UTI (50,000 U/kg i.v.) inhibited LPS (5 mg/kg i.v.)-induced increases in lung tissue levels of Egr-1, TNF-alpha mRNA, and TNF-alpha in rats. UTI inhibited LPS-induced hypotension by inhibiting pulmonary induction of inducible nitric oxide synthase (iNOS). We previously demonstrated that anti-TNF-alpha antibody and aminoguanidine, a selective inhibitor of iNOS, reduced LPS-induced hypotension in this animal model. Furthermore, we also reported that reduction of LPS-induced coagulation abnormalities in rats did not affect inflammatory responses and hypotension in this animal model. Taken together, these observations strongly suggested that UTI inhibited LPS-induced production of TNF-alpha by inhibiting activation of the extracellular signal-regulated protein kinases 1/2-Egr-1 pathway in monocytes, which might at least partly contribute to reduction of hypotension through inhibition of iNOS induction in rats given LPS.

Animals↗

PubMed2004

A different amyloid formation mechanism: de novo oculoleptomeningeal amyloid deposits after liver transplantation.

BACKGROUND: Liver transplantation has served as a treatment for patients with familial amyloidotic polyneuropathy (FAP) because variant transthyretin (TTR), the pathogenic protein of FAP, is predominantly produced by the liver. However, the effect on amyloid formation of TTR that is synthesised by the retina and the choroid plexus remains to be elucidated in FAP patients with liver transplants. OBJECTIVE: To investigate changes in ocular tissues and the central nervous system (CNS) of FAP patients after liver transplantation. DESIGN: Clinical study. SETTING: Graduate School of Medical Sciences, Kumamoto University, Japan. INTERVENTION: Transplantation of livers from cadaveric or living donors. MEASUREMENTS: Preoperative measures and postoperative (16-108 months) follow-up of clinical data, including routine ophthalmologic, neurologic, and laboratory evaluations. RESULTS: In 22 patients with FAP related to the amyloidogenic TTR (ATTR) Val30Met and 3 patients with FAP ATTR Tyr114Cys, after liver transplantation, 3 patients began to show evidence of de novo glaucoma, and 1 had vitreous opacity that was caused by the variant TTR. Another three patients showed new amyloid deposits in the pupillary margin, which could lead to glaucoma and vitreous opacity. As for changes in the CNS and levels of total protein and TTR in cerebrospinal fluid (CSF), after liver transplantation, two FAP ATTR Tyr114Cys patients exhibited de novo amyloid deposition in the leptomeninges, and total protein and TTR levels in CSF were significantly increased. CONCLUSIONS: Oculoleptomeningeal involvement in FAP was not prevented by liver transplantation because variant TTR produced by the retina and the choroid plexus forms amyloid fibrils in situ.

Adult↗

PubMed2004

Primary structures of guinea pig high- and low-molecular-weight kininogens.

Guinea pig high-molecular-weight and low-molecular-weight (HMW and LMW) kininogen cDNA were amplified from liver mRNA by RT-PCR. Their nucleotide sequences were analyzed and deduced to amino acid sequences. The HMW kininogen, composed of 607 amino acid residues with a 18-residue signal sequence, possessed the cysteine protease inhibitor domains I and II, the bradykinin domain, the histidine-rich region, and the prekallikrein-binding region. The amino acid sequence preceding the bradykinin domain was found not to be -Leu-Met-Lys- but -Leu-Thr-Arg-. Therefore, kallidin (Lys-bradykinin) and Met-kallidin are not liberated from the guinea pig kininogens. We purified the HMW kininogen protein from plasma and prepared the kinin-free form using guinea pig plasma kallikrein. Although the amino-terminal of the HMW kininogen was modified, the 25 amino-terminal residues of the light chain of the kinin-free kininogen corresponded to the deduced sequence just after the bradykinin moiety of the HMW kininogen. With regard to the LMW kininogen, the nucleotide sequence down to T(1200) as well as the amino acid sequence till Thr(382) was identical to that of the HMW kininogen. We also examined the localization of the guinea pig kininogen gene on the prometaphase lymphocyte chromosomes by fluorescence in situ hybridization method. Two pair signals were observed on a pair of homologous chromosomes, each of which is composed of two chromatids. Based on these findings, we concluded that HMW and LMW kininogens are produced from the single kininogen gene in guinea pig as in the cases of the other mammalian species reported so far.

Amino Acid Sequence↗

PubMed2004