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Biomedical subjects

Hideki Hirakata

Publications and source records attributed to Hideki Hirakata.

At least 37 records · Page 2Linked to original sources
PubMed2004

2004 Japanese Society for Dialysis Therapy guidelines for renal anemia in chronic hemodialysis patients.

The guideline committee of Japanese Society for Dialysis Therapy (JSDT), chaired by Professor F. Gejyo of Niigata University, now publishes an original Japanese guideline entitled 'Guidelines for Renal Anemia in Chronic Hemodialysis Patients'. It includes the re-evaluation of the usage of recombinant human erythropoietin (rHuEPO) with the medical and economical arguments regarding the prognosis and the quality of life of Japanese hemodialysis patients. This guideline consists of 7 sections. The first section comprises the general definition and the differential diagnosis of anemia. The hemoglobin (Hb) level of the Japanese population seemed to be low when compared with that of the European and American populations. The second section describes the target Hb level in hemodialysis patients. Multivariate analysis of the data that were collected from dialysis institutions throughout the country showed that an Hb level of 10-11 g/dL (Ht level 30-33%) at the first dialysis session in a week is the ideal range for chronic hemodialysis patients in terms of the 3-5 year survival rate. The supine position at blood sampling and the sampling timing at the first dialysis session in a week might affect the lower setting of target Hb hematocrit (Ht), compared to that of European and American guidelines. However, we particularly recommended that an Hb level of 11-12 g/dL (Ht level from 33 to 36%) at the first dialysis session in a week is desirable in relatively young patients. In the third section, the markers of iron deficiency are discussed. The Transferin saturation test (TSAT) and serum ferritin were emphasized as the standard markers. The routes of administration of rHuEPO and its dosages are written in the fourth section. The subcutaneous route was associated with the occurrence of secondary red cell aplasia due to anti-rHuEPO antibodies; however, secondary red cell aplasia was seldom observed in the venous injection. From this fact we recommend venous injection for chronic hemodialysis patients. We advocate an initial dosage of 1500 U three times per week. The fifth section deals with the factors refractory to treatment with rHuEPO. If the patient shows an inadequate response to the usage of 9000 U per week, this condition defines the inadequate response to rHuEPO in Japan. Blood transfusion must be avoided where possible. The reasons for this and the adverse effects are interpreted in section six. In the final section, the adverse effects of rHuEPO are listed. Among them, hypertension, thrombotic events and secondary red cell aplasia were emphasized as the major complications.

Anemia↗
PubMed2004

Dialysis-related hypotension as a cause of progressive frontal lobe atrophy in chronic hemodialysis patients: a 3-year prospective study.

BACKGROUND/AIM: Brain atrophy is known to develop more rapidly in hemodialysis (HD) patients than other individuals. The present study was designed to examine the role of HD-related hypotension in brain atrophy in patients on chronic HD. METHODS: By using magnetic resonance imaging, whole brain atrophy was assessed by the ventricular-brain ratio (VBR; ventricular area/whole brain area). Frontal brain atrophy was assessed by the frontal atrophy index (FAI; frontal brain area/intracranial frontal space). The number of lacunae was also counted. We studied 32 HD patients without symptomatic neurological abnormalities or diabetes mellitus: male/female ratio 19/13; mean age +/- SD 53 +/- 10 (range 28-77) years; mean HD duration +/- SD 11 +/- 6 (range 1-22) years. Magnetic resonance imagings were taken in 1995 and 1998. All dialysis-related hypotension episodes during the same period were identified from the medical records and counted. RESULTS: The VBR ranged from 8.8 to 18.7% in 1995 (12.8 +/- 2.2%) and was not different in 1998 (13.1 +/- 2.7%). However, the VBR increased by more than 5% in 14 patients, and their HD duration of 13 +/- 6 years was significantly longer than that of 18 patients with stable VBR (p < 0.05). The FAI in 1995 was 62.2 +/- 4.2% (range 55.8-71.3%) and decreased significantly to 59.7 +/- 4.7% (range 50.2-70.9%) in 1998 (p < 0.05). The change in FAI correlated significantly with both the total number of dialysis-related hypotension episodes (r = 0.45, p < 0.05) and the increase in number of lacunae (r = 0.42, p < 0.05). CONCLUSION: Our results suggest that dialysis-related hypotension plays a role in progressive frontal lobe atrophy in HD patients.

Adult↗
PubMed2004

Hyperhomocysteinemia and the development of chronic kidney disease in a general population: the Hisayama study.

BACKGROUND: Hyperhomocysteinemia has been linked with various atherosclerotic diseases, but has not been evaluated sufficiently as a risk factor for the development of chronic kidney disease (CKD) in the general population. METHODS: To clarify this issue, we followed up 1,477 community-dwelling individuals without CKD, aged 40 years or older, for 5 years and examined the effects of baseline serum total homocysteine (tHcy) levels on the development of CKD. RESULTS: During follow-up, 88 subjects experienced CKD. Baseline tHcy levels were greater in men than women (1.35 versus 1.04 mg/L [10.0 versus 7.7 micromol/L]; P < 0.01). Age-adjusted 5-year incidences were 2.2% in the low tertile, 5.4% in the middle tertile, and 8.6% in the high tertile of tHcy levels for men and 3.3%, 6.0%, and 6.9% for women, respectively. The difference between the low and high tertiles was statistically significant for both sexes ( P < 0.05). In multivariate analysis, these relationships remained substantially unchanged, even after adjustment for other confounding factors, such as systolic blood pressure, antihypertensive medication, hemoglobin A 1c level, total cholesterol level, high-density lipoprotein cholesterol level, habitual smoker status, regular alcohol intake, proteinuria, and baseline kidney function (odds ratio [OR] in the high tertile of tHcy levels, 2.09; 95% confidence interval [CI], 0.66 to 6.61 for men; OR, 2.86; 95% CI, 1.10 to 7.43 for women). Furthermore, baseline tHcy level showed a significantly inverse association with rate of change in kidney function during the 5 years after being adjusted for confounding factors, including baseline kidney function. CONCLUSION: Our findings suggest that elevated serum tHcy levels are a significant risk factor for the development of CKD in the general population.

Aged↗
PubMed2003

Antioxidant ameliorates cisplatin-induced renal tubular cell death through inhibition of death receptor-mediated pathways.

We have recently demonstrated the direct involvement of the death receptor-mediated apoptotic pathways in cisplatin-induced renal tubular cell (RTC) death. Reactive oxygen species are thought to be a major cause of cellular damage in such injury. The aim of this study was to examine the mechanism through which antioxidants ameliorate cisplatin-induced RTC death, with special emphasis on death receptor-mediated apoptotic pathways. Cisplatin was added to cultures of normal rat kidney (NRK52E) cells or injected in rats. NRK52E cells and rats were also treated with dimethylthiourea (DMTU), a hydroxyl radical scavenger. We then examined the mRNA levels of death ligands and receptors, caspase-8 activity, cell viability, cell death, renal function, and histological alterations. RT-PCR indicated cisplatin-induced upregulation of Fas, Fas ligand, and TNF-alpha mRNAs and complete inhibition by DMTU in vitro and in vivo. Cisplatin increased caspase-8 activity of NRK52E cells, and DMTU prevented such activation. Exposure to cisplatin reduced viability of NRK52E cells, examined by WST-1 assay, and increased apoptosis and necrosis of the cells, examined by terminal deoxynucleotidyl transferase dUTP nick-end labeling assay and fluorescence-activated cell sorter analysis. DMTU abrogated cisplatin-induced changes in cell viability and apoptosis and/or necrosis. Cisplatin-induced renal dysfunction and histological damage were also prevented by DMTU. DMTU did not hinder cisplatin incorporation into RTCs. Our results suggest that antioxidants can ameliorate cisplatin-induced acute renal failure through inactivation of the death receptor-mediated apoptotic pathways.

Animals↗
PubMed2003

Accumulation of 8-oxoguanine in the cellular DNA and the alteration of the OGG1 expression during ischemia-reperfusion injury in the rat kidney.

During ischemia-reperfusion (I/R) injury in the rat kidney, apoptosis was observed in the distal tubules of the cortico-medullary region and outer medulla (OM) while severe necrosis was seen in the proximal straight tubules of the OM. The majority of these changes disappeared within 2 weeks. We examined the contents of 8-oxo-2'-deoxyguanosine (8-oxo-dG), which is a major type of oxidative damage in DNA, in the rat kidney during I/R injury, and also investigated the expression level of the OGG1 gene encoding the 8-oxoguanine DNA glycosylase. High-performance liquid chromatography with an MS/MS analysis of the nuclear DNA revealed an immediate accumulation of 8-oxo-dG in the nuclear DNA prepared from the cortex and OM of the kidney 1h after I/R, and an immunohistochemical analysis demonstrated the immediate accumulation of 8-oxo-dG in the nuclei of renal tubular cells both in the cortex and OM. A delayed increase of cytoplasmic staining with anti-8-oxo-dG was observed only in the cortico-medulla and OM, where the cytoplasmic staining in the proximal tubular cells is higher than in the distal tubular cells. The level of cytoplasmic staining representing 8-oxo-dG in mitochondrial DNA, peaked at 6h after I/R and preceded the necrosis of proximal tubular cells in the OM. An RNase protection assay showed a high level of OGG1 mRNA in the normal kidney, and the level decreased within 3h only in the OM, and increased thereafter 1-7 days of I/R both in the cortex and OM. In situ hybridization showed higher levels of OGG1 mRNA expression in the renal tubules in the OM than in the cortex of the normal kidney, which decreased rapidly within 3h of I/R. Thus, the accumulation of 8-oxo-dG in the mitochondrial DNA rather than in nuclear DNA is likely to be involved in the pathogenic responses such as necrosis of renal tubular cells during I/R injury of the kidney, together with an altered level of OGG1 expression.

Animals↗
PubMed2003

Infusion of radiocontrast agents induces exaggerated release of urinary endothelin in patients with impaired renal function.

BACKGROUND: The aim of the study was to examine the role of endothelin in radiocontrast-induced nephropathy (RCN) in patients with chronic renal failure. METHODS: We measured plasma endothelin-1 (ET) and the urinary excretion of endothelin-like immunoreactivity before and after infusion of radio contrast medium (CM) in patients with normal renal function (group N; n = 6; mean serum creatinine concentration, 0.8 +/- 0.1 (SEM) mg/dl), and in another group, with renal dysfunction (group R; n = 6; 2.7 +/- 0.5 mg/dl). Half-normal saline (0.45% NaCl solution) was continuously infused in all patients for 25 h, at a rate of 100 ml/h; starting from 5 h before the infusion of CM. RESULTS: Plasma ET in group R (5.2 +/- 1.4 pg/ml) was significantly higher than in group N (0.9 +/- 0.3; P << 0.01). Urinary endothelin excretion corrected by creatinine concentration (uET/Cr) in group R (7.9 +/- 2.4 mg/g Cr) was significantly higher than in group N (1.5 +/- 0.4 mg/g Cr; P << 0.05). Urinary excretion levels of N-acetyl-Beta- d-glucosaminidase (NAG) and Beta2-microglobulin (Beta2M) were also significantly higher in group R (0.8 +/- 0.2 mU/g Cr and 670 +/- 400 mg/g Cr, respectively) than in group N (0.3 +/- 0.1 and 7.5 +/- 2.2, respectively). After CM infusion, uET/Cr in group R significantly increased, to 10.7 +/- 2.6 mg/g Cr on the next day and returned to baseline level on the third day. NAG and Beta2M showed a similar pattern, but a significant change in NAG was observed on the second day in group R. In group N, uET/Cr, NAG, and Beta2M did not change after CM infusion. Plasma ET remained unchanged throughout the observation period of 4 days in both groups. No patient developed pulmonary edema or a significant rise in serum creatinine (more than 0.5 mg/dl), caused by infusion of the amount of half-normal saline used. CONCLUSIONS: In the present study, uET/Cr increased after the administration of CM only in the patients with renal impairment. This difference in endothelin reaction may be a causal one, in that patients with renal insufficiency readily develop RCN. The infusion of half-normal saline starting before CM infusion causes no side effects and is safe for the prevention of CM-induced acute renal failure. The aim of the study was to examine the role of endothelin in radiocontrast-induced nephropathy (RCN) in patients with chronic renal failure.

Acetylglucosaminidase↗
PubMed2003

Direct involvement of the receptor-mediated apoptotic pathways in cisplatin-induced renal tubular cell death.

BACKGROUND: Tumor necrosis factor (TNF) receptor family members, such as Fas and TNF receptor 1 (TNFR1), are thought to induce apoptosis in a variety of cells and organs. Although a number of potential scenarios have been postulated for the involvement of these receptors in the pathogenesis of acute renal failure (ARF), direct evidence for their involvement in death of renal tubular cells (RTCs) and renal dysfunction is preliminary. METHODS: This study examined the roles of these receptors in RTC death in two systems: (1). in vivo murine and rat models of cisplatin-induced ARF, and (2). murine proximal tubular cells (PTCs), which were isolated from C57BL/6 (B6) mice, Fas-mutant B6-lpr/lpr mice and TNFR1-deficient mice, and normal rat kidney (NRK52E) cells in vitro. RESULTS: Reverse transcription-polymerase chain reaction indicated cisplatin-induced up-regulation of Fas, Fas ligand and TNF-alpha mRNAs in the kidney in vivo and in RTCs in vitro, both in mice and rats. In contrast, the level of TNFR1 mRNA was substantial but did not change in response to cisplatin. TNF-alpha production in cell culture medium determined by enzyme-linked immunosorbent assay (ELISA) and Fas expression determined by fluorescence-activated cell sorter (FACS) analysis increased following incubation with cisplatin in B6 PTCs. In order to examine whether Fas and TNFR1 are directly involved in RTC death and renal dysfunction, we compared cell resistance to cisplatin using a cell viability assay and FACS analysis with fluorescein isothiocyanate-conjugated annexin V and propidium iodide staining. The ratios of cell viability loss and cell death, both from apoptosis and necrosis, were higher in B6 PTCs than in other cells, while the ratios were comparable between Fas-mutant PTCs and TNFR1-deficient PTCs. Caspase-8 activity was increased in B6 PTCs, but not in Fas-mutant PTCs and TNFR1-deficient PTCs. Furthermore, the renal dysfunction and RTC death, both apoptosis and necrosis, induced by cisplatin were more severe in B6 mice in vivo. CONCLUSION: Based on these data, we conclude that the Fas- and TNFR1-mediated apoptotic pathways are directly involved in the pathogenesis of cisplatin-induced RTC death process.

Acute Kidney Injury↗
PubMed2003

Risk factors for renal glomerular and vascular changes in an autopsy-based population survey: the Hisayama study.

BACKGROUND: Information of the effect of cardiovascular risk factors on renal glomerular and vascular changes is scarce in the general population. METHOD: Between 1962 and 1994, 1394 autopsies were performed in Hisayama, for a total autopsy rate of 80%. Of these, 839 individuals who preserved adequate renal tissues and had recent health examinations data before death were eligible for the present study. We examined the degree of glomerular sclerosis, renal arteriolar hyalinosis, and arteriosclerosis, and evaluated their risk factors by means of a logistic regression model. RESULTS: The development of glomerular sclerosis, arteriolar hyalinosis, and arteriosclerosis were 16%, 16%, and 18% in men, respectively, and 27%, 15%, and 24% in women, respectively. All these frequencies increased linearly with advancing age. In the multivariate analysis, both age and systolic blood pressure were significant independent risk factors for almost all these glomerular and vascular changes. In addition, glucose intolerance and proteinuria for men were found to be significant risk factors for glomerular sclerosis. Elevated total cholesterol levels significantly increased the risk of arteriolar hyalinosis in men. Electrocardiogram (ECG) abnormalities were an independent risk factor for arteriosclerosis in both men and women, and proteinuria was an additional risk factor in women. Alcohol intake tended to have a protective effect on glomerular sclerosis and arteriosclerosis in women. CONCLUSION: Our data confirmed that age and systolic blood pressure are common risk factors for all glomerular and renal vascular changes in the general population. In addition, glucose intolerance, total cholesterol, ECG abnormalities, and proteinuria affect either glomerular or vascular changes.

Age Distribution↗
PubMed2003

Impact of interferon-gamma and interleukin-4 gene polymorphisms on development and progression of IgA nephropathy in Japanese patients.

BACKGROUND: Cytokines have an important role in the pathogenesis and disease progression of immunoglobulin A (IgA) nephropathy. The aim of this study is to investigate the impact of gene polymorphisms of T helper cell subtype 1 (T(H)1)/T(H)2 cytokines, interferon-gamma (IFN-gamma), and interleukin-4 (IL-4) on IgA nephropathy in Japanese patients. METHODS: We investigated IFN-gamma gene (IFNG) and IL-4 gene (IL4) polymorphisms in 96 patients with biopsy-confirmed IgA nephropathy who were followed-up for more than 3 years in our outpatient clinic and 61 healthy controls by polymerase chain reaction and direct sequencing methods. IFNG polymorphism was characterized as a microsatellite of intron 1. Four alleles were identified and designated IFNG 112, 114, 116, and 118, corresponding to 12, 13, 14, and 15 repeats, respectively. A variable number of tandem repeat (VNTR) polymorphisms of IL4 also were studied, and alleles were designated IL4 B1 and B2, corresponding to 2 and 3 repeats, respectively. RESULTS: In patients with IgA nephropathy, IFNG 114 allele and IFNG 114(+/+) genotype frequencies were significantly greater than in the healthy control group (60% versus 45%; P < 0.01 and 43% versus 23%; P < 0.05, respectively), but there was no difference between the IgA nephropathy and healthy control groups in frequencies of both IL4 VNTR allele and genotype. However, frequencies of IL4 B1 allele and B1/B1 genotype in patients with progressive IgA nephropathy (end-stage renal disease or doubling of serum creatinine level; n = 34) were significantly greater than corresponding values in the nonprogression group (n = 62; 79% versus 61%; P < 0.01 and 59% versus 34%; P < 0.05, respectively). We could not confirm an association between IgA nephropathy and polymorphisms of genes involved in the renin-angiotensin system. CONCLUSION: Our results suggest that IFN-gamma and IL-4 gene polymorphisms could influence disease susceptibility and disease progression in IgA nephropathy in Japanese patients. Am J Kidney Dis 41:371-379.

Adolescent↗
PubMed2003

Parathyroid cell growth in patients with advanced secondary hyperparathyroidism: vitamin D receptor and cyclin-dependent kinase inhibitors, p21 and p27.

Uraemic patients with advanced secondary hyperparathyroidism (2HPT) have nodular hyperplastic glands with a decreased vitamin D receptor (VDR) density. Previous studies have shown that nodular hyperplasia expressed a significantly lower VDR density as compared with diffuse hyperplasia, and the VDR density negatively correlated with both the glandular weight and the marker of cell proliferation. However, the mechanism by which the decreased VDR density leads to parathyroid cell proliferation remains unclear. In the myelomonocytic cell line, active vitamin D(3) is known to activate the transcription of both p21 and p27, cyclin-dependent kinase inhibitors (CDKIs), regulating the transition from the G(1) to the S phase of the cell cycle, in a VDR-dependent manner. Moreover, the overexpression of p21 and p27 inhibits cell proliferation. In order to elucidate the mechanism of parathyroid cell proliferation, the expression of CDKIs, p21 and p27, and the VDR was analysed immunohistochemically, and compared among nodular and diffuse hyperplastic parathyroid glands, and histologically normal parathyroid glands. The VDR expression in nodular hyperplasias was significantly decreased compared with either diffuse hyperplasias or normal parathyroid glands. The expression of both p21 and p27 was also significantly lower in nodular hyperplasias than in diffuse hyperplasias or normal parathyroid glands. Sections of parathyroid glands with a high expression of nuclear VDR highly expressed both p21 and p27. In nodular hyperplasias, the expression of both p21 and p27 correlated either positively with the nuclear VDR expression or inversely with the glandular weight. Therefore, the reduced expression of p21 and p27, being VDR dependent, is a major pathogenic factor for nodular parathyroid gland growth in advanced 2HPT.

Animals↗
PubMed2002

Protection by a radical scavenger edaravone against cisplatin-induced nephrotoxicity in rats.

Acute renal failure is a dose-limiting factor of cisplatin chemotherapy. Here, we show the protective effect of edaravone, a recently developed radical scavenger for clinical use, against cisplatin-induced renal dysfunction in rats. A marked increase in blood urea nitrogen and creatinine in serum, and histological changes including vacuolation, necrosis and protein casts were observed in proximal renal tubules at the fourth day after cisplatin injection (5-10 mg/kg). Repeated injection of edaravone (1-10 mg/kg, i.v. twice a day for 3 days) reversed the cisplatin-induced elevation of blood urea nitrogen and creatinine, and morphological changes in a dose-dependent manner. In particular, the protective effect of edaravone was almost complete at 10 mg/kg. Moreover, the compound was still fully effective, when it was administered only at the second day after cisplatin injection. On the other hand, the glutathione content in renal tissues lowered at the fourth day after cisplatin injection, which was reversed by the late treatment with edaravone. These findings suggest that the clinically available radical scavenger edaravone is potentially useful for the prevention of cisplatin-induced renal toxicity.

Animals↗
PubMed2002

Cerebral blood flow and vasodilatory capacity in anemia secondary to chronic renal failure.

BACKGROUND: Our previous study reported that cerebral oxygen extraction fraction (OEF) increased in hemodialysis patients with anemia. The increased OEF suggests that the cerebral vasodilatory capacity might be impaired in these patients. To clarify this issue, we measured the CO2 response in patients with anemia secondary to chronic renal failure (CRF) using positron emission tomography (PET). METHODS: Ten anemic patients with CRF (6 females and 4 males) and 6 age-matched normal controls were studied. The underlying diseases of CRF were glomerulonephritis in 8 patients, systemic lupus erythematosus (SLE) in one patient, and hypertension in one patient; in this cohort, 5 patients were on hemodialysis treatment and the remaining 5 patients were in a pre-hemodialysis state. The cerebral blood flow (CBF) was measured by the O-15 H2O bolus injection method with each patient in a resting state and during 5% CO2 inhalation. The CO2 response was estimated as the percentage change of CBF per 1 mm Hg change of PaCO2. RESULTS: The CO2 response was significantly attenuated in anemic patients with CRF in comparison to the normal controls, and it inversely correlated with the severity of anemia. There was no significant difference in the CO2 response between the hemodialysis and pre-hemodialysis patients. The CO2 response significantly correlated with CBF and the cerebral metabolic rate for oxygen (CMRO2) at rest, however, it did not correlate with OEF and cerebral blood volume (CBV). CONCLUSIONS: The present study revealed the existence of a reduced cerebral vasodilatory capacity in anemic patients with CRF, suggesting that chronic hypoxic brain damage might play a role in the impaired cerebrovascular response to CO2.

Adult↗