Biomedical subjects

Akihide Nakao

Publications and source records attributed to Akihide Nakao.

11 recordsLinked to original sources

PubMed2006

Functional polymorphisms in the vascular endothelial growth factor gene are associated with development of end-stage renal disease in males.

This study elucidates the genetic role of vascular endothelial growth factor (VEGF) as a predisposing factor for progression of chronic kidney disease. Single-nucleotide polymorphisms were genotyped and haplotype structures were determined in the 3' untranslated region (UTR) of VEGF gene, and the distribution of each haplotype in male patients with ESRD (n=101) and healthy male control subjects (n=189) was examined. The 936C/T and 1451C/T polymorphisms in the 3' UTR were in nearly absolute linkage disequilibrium, and haplotype analysis demonstrated that they were the primary responsible single-nucleotide polymorphisms. The distribution of the 936CC-1451CC genotype was significantly more frequent among patients with ESRD than among the age-matched healthy control subjects. In addition to case-control association study, the 936CC-1451CC genotype was also associated with significantly higher plasma VEGF levels in healthy individuals, but a significant association was found only in males, not in females. We also examined the effect of the 936C-1451C haplotype on mRNA stability. Consistent with the results of plasma VEGF levels, mRNA carrying 936C-1451C haplotype showed higher stability. The 936CC-1451CC genotype in the 3' UTR showed not only susceptibility for ESRD but also higher plasma VEGF levels and mRNA stability, indicating the contribution of VEGF to chronic kidney disease progression, especially in males.

Adult↗

PubMed2006

Successful treatment by double filtrate plasmapheresis in a pregnant woman with the rare P blood group and a history of multiple early miscarriages.

Individuals of P type, a rare blood group, have anti-PP(1)P(k) antibody in their serum, which causes spontaneous abortion in the early stages. We report a patient of p type suffering from multiple spontaneous abortions. We also review previously reported cases from published work. A 36-year-old woman (gravida 2, para 0) was referred to our hospital because of habitual abortion. At the third pregnancy, we started double filtration plasmapheresis (DFPP) from 7 weeks 3 days to remove the antibody. We attained rapid decline in the titer and normal fetal growth. Gradual tapering of the DFPP frequency caused neither a rebound of the titer nor growth retardation. During the course, she experienced only one episode of catheter infection as an adverse effect. At 37 weeks 3 days, after 57 DFPP repetitions, a 2496 g girl was delivered by cesarean section. The infant suffered neither from anemia nor from severe jaundice. A review of previous reports indicates that the titer of the pathogenic antibody should be kept as low as possible from the early gestational stage in P-incompatible habitual abortion cases, otherwise the case typically comes to an unfavorable outcome. Plasma exchanges with fresh plasma potentially induce contamination by either known or unknown pathogens. Such risks are reduced using DFPP because the volume of albumin solution that replaces fresh plasma is less than that by plasma exchange. The present case, along with previous reports, shows that DFPP is an effective therapy for treating P-incompatible pregnancy.

Abortion, Habitual↗

PubMed2006

Attenuation of folic acid-induced renal inflammatory injury in platelet-activating factor receptor-deficient mice.

Platelet-activating factor (PAF), a potent lipid mediator with various biological activities, plays an important role in inflammation by recruiting leukocytes. In this study we used platelet-activating factor receptor (PAFR)-deficient mice to elucidate the role of PAF in inflammatory renal injury induced by folic acid administration. PAFR-deficient mice showed significant amelioration of renal dysfunction and pathological findings such as acute tubular damage with neutrophil infiltration, lipid peroxidation observed with antibody to 4-hydroxy-2-hexenal (day 2), and interstitial fibrosis with macrophage infiltration associated with expression of monocyte chemoattractant protein-1 and tumor necrosis factor-alpha in the kidney (day 14). Acute tubular damage was attenuated by neutrophil depletion using a monoclonal antibody (RB6-8C5), demonstrating the contribution of neutrophils to acute phase injury. Macrophage infiltration was also decreased when treatment with a PAF antagonist (WEB2086) was started after acute phase. In vitro chemotaxis assay using a Boyden chamber demonstrated that PAF exhibits a strong chemotactic activity for macrophages. These results indicate that PAF is involved in pathogenesis of folic acid-induced renal injury by activating neutrophils in acute phase and macrophages in chronic interstitial fibrosis. Inhibiting the PAF pathway might be therapeutic to kidney injury from inflammatory cells.

Animals↗

PubMed2005

Haplotype analysis of NAD(P)H oxidase p22 phox polymorphisms in end-stage renal disease.

NAD(P)H oxidase is one of the most important sources of reactive oxygen species and has been demonstrated to be upregulated by angiotensin II in the kidney. Given the effect of angiotensin-converting enzyme inhibitors on the progression of both diabetic and non-diabetic renal disease, we hypothesized that the polymorphisms of NAD(P)H oxidase are associated with development of end-stage renal disease (ESRD). We examined five polymorphisms in the CYBA gene encoding the p22 phox component of NAD(P)H oxidase, including 242C/T and 640A/G polymorphisms in 467 ESRD patients and 490 healthy individuals. The T allele of the 242C/T polymorphism showed a protective effect against ESRD only in the nondiabetic (non-DM) group (P = 0.0095), and haplotype estimation revealed that the frequency of 242C-640A was higher in the non-DM group (46.7%) than in the control group (39.7%). The CC-AA genotype was still significantly associated with ESRD without diabetes after adjusting for confounding factors (P = 0.035). In contrast, there was no difference between the DM group and the control group. In conclusion, we identified a risk haplotype for nondiabetic ESRD in the CYBA gene using haplotype analysis. Haplotype analysis proved useful for elucidating the genetic contribution of NAD(P)H oxidase p22 phox to ESRD.

Adult↗

PubMed2005

Pulse total-hemoglobinometer provides accurate noninvasive monitoring.

OBJECTIVE: Rapid noninvasive measurement of total hemoglobin would be extremely useful for various clinical situations. This study determined the clinical accuracy and utility for a pulse total-hemoglobinometer using four wavelengths: 660 nm (reduced hemoglobin), 805 nm (isosbestic point), 940 nm (oxygenated hemoglobin), and 1300 nm (water density). DESIGN: Clinical trial. SETTING: University school of medicine. PATIENTS: Patients were 122 individuals (age, 18-82 yrs; 49.4 +/- 16.0 yrs [mean +/- SD]), including 71 healthy volunteers, 24 patients undergoing surgery, and 27 patients undergoing hemodialysis. INTERVENTIONS: The hemoglobinometer probe, which simultaneously indicated peripheral oxygen saturation, pulse rate, and hemoglobin, was placed on the fingertip similarly to a regular pulse oximeter. The hemoglobin values were compared with those obtained by the co-oximeter or the sodium lauryl sulfate-methemoglobin method. Those hemoglobin values were assigned to either the training set or the validation set for statistical evaluation. MEASUREMENTS AND MAIN RESULTS: Multiple regression analysis including the ratio of the pulsatile optical density (phi(ij)) derived from the four wavelengths and other factors demonstrated that the mean value of the normalized pulse wave obtained from the photodiode at 805 nm (DC805) and the ratios of DC940 and DC1300 (DC940/DC1300) were the pivotal factors in the hemoglobinometer's increased accuracy in the clinically useful range. The coefficient of determination between both methods was r2 = .81 (p < .0001) in the training set and r2 = .75 (p < .0001) in the validation set. When the cutoff value of anemia was set at 10 g/dL, and anemia was defined as <10 g/dL, the respective sensitivity and specificity of hemoglobinometer values to detect anemia in intraoperative patients were 84.3% and 84.6% (n = 20). CONCLUSIONS: The data demonstrated the necessity for consideration of light scattering in red blood cells for pulse-spectrophotometric hemoglobin measurement. This was accomplished with additional factors, such as DC805 and DC940/DC1300. With these improvements, the pulse hemoglobinometer provided noninvasive, clinically acceptable measurement of hemoglobin. The pulse hemoglobinometer is a versatile tool that might be useful for routine health checkups of neonates and young children, intraoperative monitoring of bleeding, and emergency care.

Adult↗

PubMed2004

Effects of probucol on renal function and urinary protein excretion in spontaneously hypercholesterolemic rats fed a normal or high cholesterol diet.

BACKGROUND/AIM: Spontaneously hypercholesterolemic (SHC) rats develop hypercholesterolemia and focal glomerular sclerosis, and have been thought to be a model of lipid-induced glomerular injury. However, recent studies suggest that the hypercholesterolemia might be due to secondary mechanisms by massive proteinuria. The purpose of the present study was to determine in SHC rats the effects of a high cholesterol diet on serum lipid profiles and renal function/histology, and to examine whether or not the model of lipid-induced renal injury could be developed in a short period of the time. The effects of probucol were also studied. METHODS: SHC rats were fed a high cholesterol diet for 6 weeks (H) or with probucol (HP), while control SHC rats were fed normal rat chow (N) or with probucol (P). Lipid profile and renal function/histology were examined. RESULTS: H and HP showed increased levels of urinary protein excretion and serum creatinine, as well as extremely high serum cholesterol levels, compared with N and P. HP tended to show reduced urinary protein excretion compared with H, but the difference was not statistically significant. H and HP presented histologically characteristic changes with numerous foam cells accumulated in the glomerular mesangial area, and showed glomerular sclerosis. CONCLUSION: The data demonstrate that SHC rats have an intrinsically abnormal lipid metabolism, and that probucol does not exert obviously beneficial effects on renal function or lipid-lowering action. A lipid-induced renal injury model of rats was produced in 6 weeks.

Animals↗

PubMed2004

High-throughput single nucleotide polymorphism typing by fluorescent single-strand conformation polymorphism analysis with capillary electrophoresis.

In this study, we performed high-throughput and precise single nucleotide polymorphism (SNP) typing by fluorescent capillary electrophoresis single-strand conformation polymorphism (CE-SSCP) analysis. A system composed of a multicapillary DNA analyzer, a newly developed sieving matrix, four different colors of fluorescent labels, and a multiplex polymerase chain reaction (PCR) enabled low-cost and highly reliable SNP typing. Moreover, this system enabled the estimation of SNP allele frequencies using pooled DNA samples, which should be beneficial for large-scale association studies. Thus, fluorescent CE-SSCP analysis is a useful method for large-scale SNP typing.

DNA Fingerprinting↗

PubMed2004

Radical scavenger edaravone developed for clinical use ameliorates ischemia/reperfusion injury in rat kidney.

BACKGROUND: Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) is a potent scavenger of free radicals and has the antioxidant ability to inhibit lipid peroxidation. Its protective effect on brain ischemia has been shown. This study aimed to elucidate its possible therapeutic effects on renal oxidative stress in a rat ischemia/reperfusion model. METHODS: Ischemic acute renal failure was induced by 45-minute clamp of the left renal artery followed by administration of edaravone. Renal function and pathologic findings were examined. The generation of free radicals was observed by the fluorogenic probe, dichlorodihydrofluorescein (CM-H(2)DCFDA), and lipid peroxidation was observed by immunochemical staining and Western analysis of 4-hydroxy-2-hexenal (HHE). The ability of edaravone to reduce in vitro oxidative stress was investigated using cultured human renal tubular cells (HKC-8) and the cell viability assay with Alamar blue. RESULTS: Edaravone attenuated renal function and pathologic findings significantly. The protective effect of edaravone showed the dose-response was at the same level as that of dimethylthiourea. In addition, edaravone significantly reduced the generation of free radicals in the tubular cells indicated by CM-H(2)DCFDA. Immunochemical staining and Western analysis of HHE showed significant suppression of lipid peroxidation in edaravone-treated kidney. In HKC-8 cells loaded with CM-H(2)DCFDA, a marked elevation of fluorescence was observed after exposure to hydrogen peroxide (0.5 mmol/L, for 1 hour), which was reduced by edaravone. The cell viability assay with Alamar blue also showed the protective effect of edaravone. CONCLUSION: Edaravone ameliorates renal ischemia/reperfusion injury by scavenging free radicals produced in renal tubular cells and inhibiting lipid peroxidation.

Animals↗

PubMed2002

Serum protein acrolein adducts: utility in detecting oxidant stress in hemodialysis patients and reversal using a vitamin E-bonded hemodialyzer.

Accumulating evidence indicates that protein modification by acrolein is one of the major hallmarks of atherosclerosis. The purpose of the present study was to evaluate the serum acrolein-modified protein adduct (Acr) level in end-stage renal disease (ESRD), and to elucidate the efficacy of vitamin E-bonded hemodialyzer in reducing Acr in a crossover trial. A significant increase in Acr was found in ESRD patients compared with healthy controls (p <.001). In ESRD, the Acr level of those patients with type 2 diabetes mellitus (DM) was significantly higher compared with the non-DM group (p <.05). Forty-one ESRD patients who exhibited Acr levels higher than the mean value in ESRD were treated by vitamin E-bonded hemodialyzer for 6 months. After 6 months of treatment, Acr levels were decreased to those found in healthy individuals (p <.001). When hemodialyzers were switched back from vitamin E bonded to the original regular ones, Acr levels increased to nearly their initial levels after 3 months (p <.001), compared with the 6 month time point. These results suggest the potential of Acr as an oxidative stress marker in ESRD, and that vitamin E-bonded hemodialyzer treatment is a reasonable approach to reduce oxidative stress in ESRD.

Acrolein↗

PubMed2002

Quantifying porphobilinogen deaminase mRNA in microdissected nephron segments by a modified RT-PCR.

BACKGROUND: Quantifying mRNA levels by reverse transcription-polymerase chain reaction (RT-PCR), although widely exercised, is still difficult. METHODS: A modified quantitative RT-PCR in which genomic DNA was used as standard was developed. The quantity of mRNA was expressed as the ratio of the PCR product from cDNA and that from genomic DNA (CG ratio). Nephron distribution of porphobilinogen deaminase (PBGD) mRNA was examined in microdissected nephron segments using the method. The enzyme activity and mRNA quantity of PBGD also were measured in tissue homogenates. RESULTS: Tubular segments expressed substantially more PBGD mRNA than glomeruli (expressed as CG ratios, 1.04 +/- 0.10 in glomeruli, 4.53 +/- 0.32 in PCT, 5.71 +/- 0.25 in PST, 5.13 +/- 0.52 in mTAL, 5.29 +/- 0.20 in cTAL, 4.05 +/- 0.35 in DCT, 2.88 +/- 0.25 in CCD, and 4.90 +/- 0.24 in OMCD). PBGD mRNA level in liver homogenate (3.17 +/- 0.36) was much higher than glomeruli but lower than most of the tubular segments. The enzyme activity in tissue homogenates correlated well with mRNA levels. CONCLUSION: The method reported here is simple and reliable, and especially suitable for quantitating specific mRNA amounts in minute tissue samples such as microdissected nephron segments.

Actins↗

PubMed2002

Association of eNOS Glu298Asp polymorphism with end-stage renal disease.

Nitric oxide (NO) derived from endothelial cells is profoundly related to the maintenance of physiological vascular tone. Impairment of endothelial NO generation brought about by gene polymorphism is considered the major deterioration factor for progressive renal disease, including diabetic nephropathy. The present study aimed to elucidate the Glu298Asp polymorphism of endothelial NO synthase (eNOS) in patients with end-stage renal disease (ESRD) and its role as a predisposing factor for cardiovascular complications. Glu298Asp in exon 7 of the eNOS gene was determined by polymerase chain reaction, followed by restriction fragment length polymorphism analysis, in ESRD patients (n=185) and compared with that of unrelated healthy individuals (n=304). The occurrence of 298Asp was significantly higher in the ESRD group (P=0.0020; odds ratio [OR] 1.65; 95% confidential interval [CI]: 1.21 to 2.25). In this group, 72 patients had type 2 diabetes mellitus (DM). Although 298Asp did not reach a significant level in the non-DM ESRD subgroup, the occurrence of 298Asp was significantly higher in DM-derived ESRD patients (P=0.0010; OR 2.02; 95% CI: 1.37 to 3.07). The functional effect of the Glu298Asp was examined using Chinese hamster ovary (CHO) cells stably overexpressing either 1917G or 1917T. NO-selective electrode measurements and fluorometric nitrite assay revealed a statistically significant difference in NO production or nitrite accumulation between CHO 1917G and 1917T (P<0.01). These data indicated that Glu298Asp is the predisposing factor in ESRD, especially DM-derived ESRD. The functional difference in NO generation depending on eNOS with either glutamate or aspartate at position 298 was also confirmed in vitro.

Animals↗