Search PubMed⌕ Search

Biomedical subjects

A Okuyama

Publications and source records attributed to A Okuyama.

At least 19 recordsLinked to original sources
PubMed2005

Expression of inhibin alpha, glial cell line-derived neurotrophic factor and stem cell factor in Sertoli cell-only syndrome: relation to successful sperm retrieval by microdissection testicular sperm extraction.

BACKGROUND: Microdissection testicular sperm extraction (TESE) has provided new hope for successful sperm retrieval to patients with Sertoli cell-only syndrome (SCO). We determined expression of the inhibin alpha subunit, glial cell line-derived neurotrophic factor (GDNF) and stem cell factor (SCF) in Sertoli cells obtained from patients with SCO immunohistochemically and compared expression rates with rates of microdissection TESE sperm retrieval. METHODS: Testicular biopsy specimens were obtained from 52 men with non-obstructive azoospermia who underwent microdissection TESE and were diagnosed with SCO by histological analysis. RESULTS: All specimens showed intense staining for the inhibin alpha subunit. Moderate or intense staining for GDNF was observed in 65.8% of specimens. All but one showed moderate or intense staining for SCF. Among specimens negative for GDNF, the sperm retrieval rate was significantly higher (100%) for specimens with intense staining for SCF than for specimens with no or moderate staining (30.7%) (P<0.05) for SCF. CONCLUSION: GDNF expression differs among patients with SCO. The sperm retrieval rate was high in cases of no staining for GDNF and intense staining for SCF.

Adult↗
PubMed2005

Increased expression of renin in chronic allograft nephropathy.

BACKGROUND: Chronic allograft nephropathy (CAN) is the main cause of renal transplant failure in the first decade posttransplant. The precise pathogenetic mechanism for CAN is not completely understood. A possible role of renin-angiotensin system for CAN has been suggested through clinical observations that angiotensin-converting enzyme inhibition and angiotensin II receptor blockers prevent CAN. METHODS: Distribution of renin-positive cells in allograft biopsy specimens was examined immunohistochemically in 23 renal transplant recipients diagnosed with CAN Biopsy specimens obtained from seven recipients with stable renal function were examined as controls. Histologic evaluation was performed based on the Banff 97 classification. RESULTS: Renin-positive cells were found in the juxtaglomerular apparatus (JGA) adjoining the afferent arterioles in both groups. When the number of renin-positive cells in JGA was defined as a renin index, it was significantly higher in the CAN than the control group (P = .007). There was no significant difference in age, interval between transplantation and biopsy, and blood pressure between groups. Only a significantly higher serum creatinine was found in the CAN group. CONCLUSIONS: The increased renin-positive cells in JGA suggest a significant role of the intrarenal renin-angiotensin system activation in the development of CAN.

Adult↗
PubMed2005

Electroporation-mediated HGF gene transfection protected the kidney against graft injury.

The annual rate of kidney graft loss caused by chronic allograft nephropathy (CAN) has not improved over the past decade. Recent reports suggest that acute renal ischemia results in development of CAN. The goal of the present study was to assess the renoprotective potential and safety of hepatocyte growth factor (HGF) gene transfer using a porcine kidney transplant warm ischemia injury model. Following left porcine kidney removal, 10 min of warm ischemic injury was intentionally induced. Next, the HGF expression vector or vehicle was infused into the renal artery with the renal vein clamped ex vivo, and electric pulses were discharged using bathtub-type electrodes. Kidney grafts were then transplanted after removing the right kidney. Histopathological examination of vehicle-transfected kidney transplant revealed initial tubular injury followed by tubulointerstitial fibrosis. In contrast, HGF-transfected kidneys showed no initial tubular damage and no interstitial fibrosis at 6 months post-transplant. We conclude that electroporation-mediated ex vivo HGF gene transfection protects the kidney against graft injury in a porcine model.

Animals↗
PubMed2004

Investigation of the pharmacokinetics of cyclosporine in patients following long-term administration after a kidney transplant: comparison of Neoral and Sandimmune.

A crossover administration of Neoral and Sandimmune was performed in 43 renal allograft recipients who had been on cyclosporine maintenance therapy for 2 to 19 years posttransplant to investigate the pharmacokinetics of cyclosporine. Although there was no difference in C0 values (trough values) when Neoral and Sandimmune were administered at the same doses, AUC(0-4) and AUC(0-12) values of Neoral were 1.57- and 1.36-fold greater than those of Sandimmune, respectively. For both Neoral and Sandimmune, there was a high correlation between the C2 value and AUC(0-4). The Pearson's product-moment coefficient for the correlation between the C2 value and AUC(0-4) was R=0.91642. On the other hand, the correlation with the C0 value (trough value) was low (R=0.53181). During the period of the study, there was no acute rejection episode, onset of adverse drug reaction symptoms, or marked change in laboratory test values.

Adult↗
PubMed2004

Risk factors for graft loss in patients with recurrent IGA nephropathy after renal transplantation.

BACKGROUND: The recurrence rate of IgA nephropathy (IgAN) in transplanted kidneys has been reported to be >50%. Although recurrent IgAN has a benign clinical course, recent data suggest that it leads to graft loss in a substantial number of patients. METHODS: We performed a retrospective single-center analysis of 34 renal transplant recipients, with biopsy-proven IgAN as the cause of end-stage renal failure. RESULTS: Renal allograft biopsies were performed in 30 patients, of whom 24 did and 6 did not have biopsy-confirmed recurrent transplant IgAN. Recurrent transplant IgAN was more often detected in men and at later timepoints after post-transplantation. Four patients with recurrent transplant IgAN progressed to graft failure. Progression to graft failure was associated with worsened renal function, higher systolic blood pressure, and the lack of presenation of angiotensin-converting enzyme inhibitors (ACEs) at the time of allograft biopsy. Immunologic factors such as frequency of acute rejection, HLA typing, and immunosuppression did not show a relation to recurrence or graft loss. CONCLUSIONS: Recurrent transplant IgAN increased with long-term graft survival and risk factors for graft loss due to recurrent IgAN were similar to those among IgAN in native kidneys.

Adult↗
PubMed2004

Comparison of histopathological characteristics of allograft biopsy between responder and non-responder to antiproteinuric effect of angiotensin-converting enzyme inhibitor (ACEI).

Angiotensin-converting enzyme inhibitor (ACEI) has become recognized as agents that have renoprotective effects in the treatment of progressive renal diseases including post-transplant kidneys. Previously we demonstrated the safety and effectiveness of ACEI treatment on the hypertensive proteinuric post-transplant patients (N = 10) who had been followed up for 12 months. However, not all patients show good response in urinary protein reduction. We aimed to analyse the histopathological factor(s) affecting the responsiveness of proteinuria to ACEI treatment. Fourteen post-transplant patients with proteinuria who were treated with ACEI and underwent allograft biopsy were analysed. Eight patients showed 50% or more reduction in proteinuria (responder). The other 6 patients showed less (< 50%) reduction in proteinuria (non-responder). There was no difference in clinical characteristics (BP, renal function, donor age, recipient body mass index), dietary sodium or protein intake, and diuretic use between the two groups. As a histopathological characteristic, glomerular size in responder group was significantly larger than that in non-responder group. This suggests that the large glomerular size at least partly contributes to the responsiveness in urinary protein reduction to ACEI treatment in kidney allograft recipients with proteinuria.

Adult↗
PubMed2002

Susceptibility locus for non-obstructive azoospermia is localized within the HLA-DR/DQ subregion: primary role of DQB1*0604.

Non-obstructive azoospermia is a male infertility characterized by no or little sperm in semen as a result of a congenital dysfunction in spermatogenesis. Previous studies have reported a higher prevalence of particular human leukocyte antigen (HLA) antigens in non-obstructive azoospermia. As the expression of the RING3 gene located in the HLA class II region was predominant in the testis, mainly around spermatids and pachytene spermatocytes, it is tempting to speculate that RING3 is one of the strong candidate genes responsible for the pathogenesis of the disease. In this study, the genetic polymorphism in the RING3 gene was investigated by the direct sequencing technique. As a result, a total of 14 single nucleotide polymorphisms were identified. Among them, six were localized in the coding region but none of them was accompanied by an amino-acid substitution. No significant difference in the allelic distribution at these 14 polymorphic sites was observed between the patients and healthy controls, suggesting that the susceptible gene for non-obstructive azoospermia is not the RING3 gene. Then, in order to map the susceptibility locus for non-obstructive azoospermia precisely within the HLA region, 11 polymorphic microsatellite markers distributed from the SACM2L gene just outside the HLA class II region (187 kb telomeric of the DPB1 gene) to the OTF3 gene in the HLA class I region were subjected to association analysis in the patients. Statistical analysis of distribution in the allelic frequency at each microsatellite locus demonstrated that the pathogenic gene for non-obstructive azoospermia is located within the HLA-DR/DQ subregion. In fact, DRB1*1302 and DQB1*0604 were found to be strongly associated with non-obstructive azoospermia by polymerase chain reaction-based DNA typing. Further, haplotype analysis suggested that the DQB1*0604 allele may play a decisive role in the pathogenesis of non-obstructive azoospermia.

Alleles↗
PubMed2002

Inhibition of CN (protein phosphatase-2B) suppresses Ca2+-mediated acid secretion in rats.

BACKGROUND AND AIM: It has been suggested that CN (calcineurin, protein phosphatase-2B) regulates signal transduction, particularly in various secretory cells. In this study, we examined whether CN plays a role in stimulus-secretion coupling of gastric parietal cells. MATERIALS AND METHODS: Localization of CN in gastric epithelial cells was examined immunohistochemically. The role of CN in the acid secretion pathway of gastric parietal cells was assessed by evaluating the effect of FK506, a specific inhibitor of CN, on gastric acid secretion in pylorus-ligated rats. In addition, the effect of FK506 on secretagogue (carbachol, tetragastrin and histamine)-stimulated acid secretion was investigated in lumen-perfused rats. RESULTS: CN was specifically expressed in gastric parietal cells and chief cells of the gastric mucosal epithelium immunohistochemically. FK506 dose-dependently inhibited gastric acid secretion in pylorus-ligated rats. In lumen-perfused rats, FK506 completely inhibited acid secretion prestimulated by carbachol and tetragastrin, agonists known to increase cytosolic Ca2+, but did not affect acid secretion prestimulated by histamine. CONCLUSIONS: Our findings demonstrate that FK506 has a potent antisecretory effect in parietal cells through inhibition of only Ca2+-mediated acid secretion pathways. As FK506 is known to specifically inhibit CN, which plays an important role in signal transduction in various secretory cells, protein dephosphorylation signalling might also be crucial for gastrin and M3 muscarine receptor-mediated stimulation of proton pump.

Animals↗
PubMed2002

Conventional multiple or microdissection testicular sperm extraction: a comparative study.

BACKGROUND: Testicular sperm extraction (TESE) with ICSI is becoming the first-line treatment for non-obstructive azoospermia (NOA). Recently, the sperm retrieval rate (SRR) by microdissection TESE was reported to be higher than by conventional TESE. However, a comprehensive comparison between multiple and microdissection TESE patients including histological findings has not been reported. METHODS: Patients with NOA who underwent microdissection TESE (n = 56) or multiple TESE (n = 37) were compared. Pre-operative characteristics were similar between groups. In addition, microscopic findings during microdissection TESE also were investigated. RESULTS: Operative time was significantly longer for microdissection TESE than for multiple TESE. Histological examination suggested that spermatogenesis was relatively more impaired in the microdissection TESE group than in the multiple TESE group. Despite this, SRR by microdissection TESE (42.9%) appeared higher than by conventional TESE (35.1%) although this observation failed to reach statistical significance. Seventeen of 26 patients (65.4%) with heterogeneous tubule were successful for sperm retrieval. No severe operative complications occurred in any patient in either group, and no patient required post-operative hormone replacement to treat hypogonadism. CONCLUSIONS: Microsurgical technique is safe and may improve SRR for TESE in a variety of patients with NOA, especially patients with heterogeneous testicular tubules.

Adult↗
PubMed2001

Characterization of low-intensity lesions in the peripheral zone of prostate on pre-biopsy endorectal coil MR imaging.

The aim of this study was to determine which morphological features of low-intensity lesions in the peripheral zone of the prostate are predictable of prostate cancer on pre-biopsy T2-weighted integrated endorectal phased-array MR images. The MR examinations were performed in 69 consecutive patients with elevated level of prostate-specific antigen (>4 ng/ml) and/or a positive digital rectal examination before transperineal 12-site biopsy. Two radiologists evaluated presence of lesions, their morphological features, and possibility of malignancy in divided into four sections of the peripheral zone. Imaging analysis findings were compared with biopsy results. Discriminative features were selected by stepwise logistic regression. Descriptive statistics and receiver operating characteristics (ROC) curves were also calculated. Sixty-eight benign lesions and 23 malignant lesions were found. Wedge shape and diffuse extensions without mass effect were significantly associated with benignity ( P=0.0105 and 0.002, respectively). Lesion size was significantly associated with malignancy ( P=0.0001). For evaluating probability of malignancy for lesions, regression model showed a comparable accuracy with the total impression for the readers in ROC analysis (Az 0.9095 vs 0.9266, respectively). Wedge shape, diffuse extension without mass effect, and size are the morphological features of low-intensity lesions in the peripheral zone on pre-biopsy T2-weighted MR images that give the best prediction of malignancy.

Aged↗
PubMed2001

Rational design, discovery, and synthesis of a novel series of potent growth hormone secretagogues.

In the joint experimental and computational efforts reported here to obtain novel chemical entities as growth hormone secretagogues (GHSs), a small database of peptides and non-peptides known to have GHS activity was used to generate and assess a 3D pharmacophore for this activity. This pharmacophore was obtained using a systematic and efficient procedure, "DistComp", developed in our laboratory. The 3D pharmacophore identified was then used to search 3D databases to explore chemical structures that could be novel GHSs. A number of these were chosen for synthesis and assessment of their ability to release growth hormone (GH) from rat pituitary cells. Among the compounds tested, those with a benzothiazepin scaffold were discovered with micromolar activity. To facilitate lead optimization, a second program, a site-dependent fragment QSAR procedure was developed. This program calculates a library of chemical and physical properties of "fragments" or chemical components in a known pharmacophore and determines which, if any, of these properties are important for the observed activity. The combined use of the 3D pharmacophore and the results of the site-dependent fragment QSAR analysis led to the discovery and synthesis of a novel series of potent GHSs, a number of which had nanomolar in vitro activity.

Animals↗
PubMed2001

Potential mechanism for the effects of dexamethasone on growth of androgen-independent prostate cancer.

BACKGROUND: Dexamethasone, a synthetic glucocorticoid, has clinical benefit in patients with hormone-refractory prostate cancer (HRPC), but the mechanisms responsible for its effects are unknown. The nuclear factor-kappaB (NF-kappaB)-dependent cytokine interleukin (IL) 6 (IL-6) is thought to stimulate growth of HRPC. Because dexamethasone interferes with NF-kappaB activation, we determined whether dexamethasone inhibits prostate cancer growth by working through the glucocorticoid receptor (GR) to interfere with NF-kappaB-IL-6 pathway. METHODS: Three human prostate cancer cell lines (DU145, PC-3, and LNCaP) were assessed for GR expression and responsiveness to dexamethasone. Levels of GR, NF-kappaB, and the cytoplasmic NF-kappB inhibitor IkappaBalpha were determined by western blotting and of IL-6 by enzyme immunoassay. The subcellular localization of NF-kappaB was analyzed by immunofluorescence. The effects of dexamethasone (thrice weekly injections of 1 microg/mouse) on DU145 xenografts in nude and severe combined immunodeficient (SCID) mice were evaluated. GR expression in human prostate cancers was assessed by immunohistochemistry. All statistical tests were two-sided. RESULTS: Dexamethasone dose dependently decreased GR levels and inhibited the growth of DU145 and PC-3 but not LNCaP cells (DU145 cells, P< .001; PC-3 cells, P = .009). Dexamethasone increased IkappaBalpha protein levels and the cytosolic accumulation of NF-kappaB in DU145 cells and decreased secreted IL-6 levels to 37 pg/mL (95% confidence interval [CI] = 33 pg/mL to 41 pg/mL), compared with 164 pg/mL (95% CI = 162 pg/mL to 166 pg/mL) secreted by ethanol-treated control cells. Dexamethasone inhibited the growth of DU145 xenografts in nude (P = .006) and SCID (P = .026) mice without affecting GR levels. Eight of 16 human prostate cancers expressed GR at high levels (>or=30% GR-positive cells). CONCLUSION: Dexamethasone inhibited the growth of GR-positive cancers, possibly through the disruption of the NF-kappaB-IL-6 pathway.

Androgens↗
PubMed2001

Processing of beta-dystroglycan by matrix metalloproteinase disrupts the link between the extracellular matrix and cell membrane via the dystroglycan complex.

The dystroglycan complex is a membrane-spanning complex composed of two subunits, alpha- and beta-dystroglycan. alpha-dystroglycan is a cell surface peripheral membrane protein which binds to the extracellular matrix (ECM), whereas beta-dystroglycan is an integral membrane protein which anchors alpha-dystroglycan to the cell membrane. The dystroglycan complex provides a tight link between the ECM and cell membrane. Dysfunction of the dystroglycan complex has commonly been implicated in the molecular pathogenesis of severe forms of hereditary neuromuscular diseases, including Duchenne muscular dystrophy, Fukuyama-type congenital muscular dystrophy and sarcoglycanopathy (LGMD2C, -D, -E and -F). To begin to clarify the pathway by which the dysfunction of the dystroglycan complex could lead to muscle cell degeneration, we investigated the proteolytic processing of the dystroglycan complex in this study. We demonstrate that (i) a 30 kDa fragment of beta-dystroglycan is expressed in peripheral nerve, kidney, lung and smooth muscle, but not skeletal muscle, cardiac muscle or brain, and (ii) this fragment is the product of proteolytic processing of the extracellular domain of beta-dystroglycan by the membrane-associated matrix metalloproteinase (MMP) activity. Importantly, furthermore, we demonstrate that this processing disintegrates the dystroglycan complex. Our results indicate that the processing of beta-dystroglycan by MMP causes the disruption of the link between the ECM and cell membrane via the dystroglycan complex, which could have profound effects on cell viability. Based on these and previously reported findings, we propose a hypothesis that this processing may play a crucial role in the molecular pathogenesis of sarcoglycanopathy.

Animals↗
PubMed2001

Rapid and simultaneous determination of mycophenolic acid and its glucuronide conjugate in human plasma by ion-pair reversed-phase high-performance liquid chromatography using isocratic elution.

A high-performance liquid chromatographic method has been developed for the simultaneous determination of mycophenolic acid (MPA) and its glucuronide conjugate (MPAG) in human plasma. The method involves protein precipitation with acetonitrile, followed by ion-pair reversed-phase chromatography on C18 column, with a 40 mM tetrabutyl ammonium bromide (TBA)-acetonitrile (65:35, v/v) mobile phase. A 20-microl volume of clear supernatant was injected after centrifugation, and the eluent was monitored at 304 nm. No interference was found either with endogenous substances or with many concurrently used drugs, indicating a good selectivity for the procedure. Calibration curves were linear over a concentration range of 0.5-20.0 microg/ml for MPA and 5-200 microg/ml for MPAG. The accuracy of the method is good, that is, the relative error is below 5%. The intra- and inter-day reproducibility of the analytical method is adequate with relative statistical deviations of 6% or below. The limits of quantification for MPA and MPAG were lower than 0.5 and 5.0 microg/ml, respectively, using 50 microl of plasma. The method was used to determine the pharmacokinetic parameters of MPA and MPAG following oral administration in a patient with renal transplantation.

Calibration↗
PubMed2001

Safety evaluation of hemagglutinating virus of Japan--artificial viral envelope liposomes in nonhuman primates.

We tested, in cynomolgus monkeys, the safety and effectiveness of a hybrid liposome vector, hemagglutinating virus of Japan (HVJ)--artificial viral envelope (AVE) liposomes, for human therapeutic gene transfer in a series of experiments. In a repetitive intramuscular administration study, vehicle control macaques (n = 2), which were treated with HVJ--AVE liposome suspension, received repetitive intramuscular injections of 2 ml of test substance. Human hepatocyte growth factor (HGF) cDNA-inserted expression vector (pUC-SR alpha/HGF) injection animals (n = 2), which were treated with HVJ--AVE liposome suspension containing pUC-SR alpha/HGF, received repetitive intramuscular injection of 2 ml of test substance. General body condition, hematology, blood chemistry, and serum HGF were determined sequentially before treatment and 7, 21, 28, and 29 days after treatment. Elevations in HGF were detected in monkeys injected with pUC-SR alpha/HGF. After this observation period, macaques were killed for autopsy and histological examination. pUC-SR alpha/HGF was detected by polymerase chain reaction (PCR) analysis in the liver, spleen, and at the injection site. In single intravenous administration study, control macaques (n = 4) received a single intravenous injection of 10 ml of physiological saline. Vehicle control animals (n = 5) received a single intravenous injection of 10 ml of HVJ--AVE liposome suspension. DNA-treated animals (n = 7) received a single intravenous injection of 10 ml of HVJ--AVE liposome suspension containing plasmid DNA [pcDNA 3.1(+)]. General body condition, body weight, hematology, blood chemistry, and urine composition were determined sequentially before treatment and 1, 14, 21, and 28 days after treatment. After this observation period, macaques were killed for autopsy and histological examination. pcDNA 3.1(+) was detected by PCR analysis on day 1 in lung, liver, and spleen of all monkeys, in kidney of one of two monkeys, and in heart of one of two monkeys. However, no DNA was detected in any of the tissues examined on days 14, 21, and 28. No virus genomic RNA was detected by reverse transcription (RT)-PCR analysis with HVJ-specific primers. In this series of safety evaluations, the animals tolerated the safety study with no change in body weight or general condition. No hematological changes or alterations in blood chemistry or urine composition was detected. Moreover, no histological changes were observed. This safety evaluation study demonstrates the safety, feasibility, and therapeutic potential of the novel transfection vehicle, HVJ--AVE liposomes, in humans.

Animals↗
PubMed2001

Changes in lipid metabolism and effect of simvastatin in renal transplant recipients induced by cyclosporine or tacrolimus.

Hyperlipidemia is frequently developed following renal transplantation and results in worsening of the patient's prognosis. In study 1, the effects of immunosuppressants, cyclosporine (CsA) and tacrolimus on serum lipids were compared in-patients undergoing renal transplantation. The study included 32 cases of renal transplantation recipients who randomized to the CsA treatment group (15 patients) and the tacrolimus group (17 patients). Before and 1 month after the transplantation, we assessed the serum lipid levels, apolipoprotein levels, the concentrations of cholesterol in the respective lipoprotein fractions and the enzyme activities related to lipid-metabolism. The serum lipid levels in both groups were significantly increased at 1 month after renal transplantation. In the CsA group, there were significant increases in cholesterol contents in very-low-density lipoprotein (VLDL), LDL2 and HDL2 fractions, whereas, in the tacrolimus group, cholesterol content was increased in VLDL and HDL2 fractions. In study 2, 1 month after renal transplantation, 19 patients with hypercholesterolemia (total cholesterol (TC) >200 mg/dl) and hypertriglyceridemia (triglyceride (TG) >150 mg/dl) were treated with simvastatin 5-10 mg/day for 6 months. Simvastatin treatment significantly decreased serum TC (240+/-29-200+/-22 mg/dl, P<0.001), low-density lipoprotein cholesterol (LDL-C; 114+/-20-99+/-17 mg/dl, P<0.05) and TG levels (217+/-103-130+/-38 mg/dl, P<0.01). In addition, there were significant decreases in very-low-density lipoprotein cholesterol (VLDL-C; 53+/-20-34+/-15 mg/dl, P<0.001). The Cmax and AUC of simvastatin were increased about eight-fold, when simvastatin was given in combination with CsA. In contrast, no significant changes in simvastatin levels were observed when combination with tacrolimus. Although simvastatin levels were increased with CsA, there were no abnormal changes in renal and liver functions, creatinine phosphokinase (CPK) levels or in incidence of adverse effects.

Adult↗