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S Arita

Publications and source records attributed to S Arita.

At least 19 recordsLinked to original sources
PubMed2001

Involvement of platelet-derived growth factor and histocompatibility of DRB 1 in chronic renal allograft nephropathy.

BACKGROUND: The role of activated T cells in graft arteriosclerosis, which is observed in chronic renal allograft nephropathy, and the involvement of major histocompatibility complex (MHC) incompatibility remain to be determined. We examined the effect of T lymphocytes that were obtained from renal transplant patients undergoing chronic rejection treated with cyclosporine (CsA) on platelet-derived growth factor (PDGF)-induced proliferation of cultured human vascular smooth muscle cells (SMC) and compared the proliferation activity of T lymphocytes with MHC incompatibility, especially DRB 1 mismatch. METHODS: Renal transplant patients with continued allograft function, who survived more than 1 year after transplantation, were recruited. Chronic rejection was documented by graft-biopsy findings together with increasing serum creatinine levels (10-20% per year). After the incubation of supernatant (conditioning medium) of cultured T cells from CsA-treated renal transplant patients with chronic rejection (n=18) and with normal renal function (n=14) as control, normal subjects (n=11) and chronic hemodialysis (HD) patients (n=5) with cultured SMC in the presence or absence of PDGF, DNA synthesis (3H-thymidine uptake) of SMC was examined. The in vitro effects of CsA on DNA synthesis of cultured SMC were also evaluated. RESULTS: The supernatant of cultured T cells from renal transplant patients with chronic rejection stimulated PDGF-induced DNA synthesis of SMC in a dose-dependent manner, showing significant enhancement as compared with control transplant patients, normal subjects, and chronic HD patients. The supernatant itself did not significantly stimulate DNA synthesis of SMC. No significant in vitro stimulation of CsA on DNA synthesis was observed. The supernatant of T cells obtained from recipients undergoing chronic rejection with two DRB 1 mismatches showed significantly higher enhanced activity of PDGF-induced DNA synthesis than the supernatant from those recipients without mismatch of DRB 1. On the other hand, no significant correlation of the enhanced activity by T cell supernatant to HLA A and B mismatch numbers was observed. CONCLUSIONS: Growth factor-promoting factors(s) derived from activated T cells associated with MHC class II DR expression, which promotes PDGF-induced proliferation of SMC, exists in renal transplant patients with chronic renal allograft nephropathy, and is probably involved in arteriosclerosis of the graft kidney.

Adult↗
PubMed2001

A simple titration method for determining Chlamydia infectivity using an image analyzing system.

In the biological study of Chlamydia, it is very important to determine the infectivity titer of the organism. For many years researchers used the serial dilution method to determine this titer. This method consists of diluting the material to be examined, inoculating suitable dilutions into susceptible cell cultures and cultivating them. The number of inclusions formed in host cells can be calculated with the naked eye under a microscope. The precision and accuracy of this method, however, depend on the number of inclusions per field and the number of fields counted. In this report, we present a simple and rapid method for counting a large number of inclusions using an image analysis system and an appropriate number of samples, and propose a sampling method based on a statistical analysis of the data obtained with 84 microscopic fields.

Animals↗
PubMed2001

Medical versus surgical androgen suppression therapy for prostate cancer: a 10-year longitudinal cost study.

PURPOSE: We provide a relative cost comparison of medical versus surgical androgen suppressive therapy for prostate cancer. MATERIALS AND METHODS: Comparison is based on a cohort of 96 patients who began androgen suppressive therapy for prostate cancer between 1988 and 1990. Patients were followed until death or the end point of study in June 2000 at which time 15% were alive. Current Medicare orchiectomy reimbursements were compared to 1999 wholesale drug costs. RESULTS: For an individual patient the cost of luteinizing hormone releasing hormone (LH-RH) agonist treatment surpassed the cost of surgery at less than 4.2 to 5.3 months, and for combined androgen blockade (LH-RH agonists and nonsteroidal antiandrogens) at less than 2.7 to 3.4 months. For 5 (5.2%) patients on combined androgen blockade and 6 (6.3%) on LH-RH agonists alone, medical therapy would have had a cost advantage over bilateral orchiectomy. For the androgen suppression cohort the cost of LH-RH agonist treatment was 10.7 to 13.5 times and combined androgen blockade was 17.3 to 20.9 times the cost of bilateral orchiectomy. Urology resource use comparisons are provided. These findings significantly underestimate the cost advantage of surgery. A seventh of the patients were alive at study end point, and prostate specific antigen induced stage shifting and changes in practice patterns resulted in earlier and more frequent androgen suppressive treatment. CONCLUSIONS: Except for patients with short anticipated survivals current medical androgen suppressive treatment options are more costly than bilateral orchiectomy. There is a need for a cost comparable medical option to orchiectomy.

Androgen Antagonists↗
PubMed2001

Increased islet viability by addition of beraprost sodium to collagenase solution.

The digestion of pancreatic tissue with collagenase is an essential part of the islet isolation procedure. However, the process exposes islets to various types of harmful factors, including collagenase contaminants, enzymes released from the acinar cells, warm ischemia, and mechanical agitation. Nitrogen oxide production and cytokine release may also contribute to islet cell damage. Protection of islets from such damage would improve the islet yield, survival, and function. Beraprost sodium (BPS) is a prostaglandin I2 analogue, is stable in aqueous solution, and has a cytoprotective effect on various types of cells. BPS has been shown to improve the yield and function of cryopreserved and/or cultured islets. These findings prompted us to examine its cytoprotective effect on islets during the islet isolation process. Canine islets were isolated by means of a two-step digestion method and purified on Euro-Ficoll density gradient solutions (the procedure used for human islets). BPS at a concentration of 100 nM was added to the collagenase solution. After purification, the islet yield was 434,561 +/- 35.691 islet number expressed as 150 microm equivalent size (IEQ)/pancreas or 8,799 +/- 345 IEQ/g of pancreas in the BPS group and 349,987 +/- 52,887 IEQ/pancreas or 7,998 +/-1610 IEQ/g of pancreas in the control group (n = 8, each). The percent viability was 88.5 +/- 0.7% in the BPS group and 82.0 +/-0.9% in the control group (P < 0.01). Therefore, the recovery of viable islets (calculated by islet number x % viability) was 384,586 +/- 46,804 IEQ/pancreas (7,743 IEQ/g) in the BPS group and 286,989 +/- 43,367 IEQ/pancreas (6,558 IEQ/g) in the control group (P < 0.02). After culture, significantly higher numbers of islets were also recovered in the BPS group than in the control group. The islet insulin content was significantly higher in the BPS group than controls (237.8 +/- 38.5 versus 92.3 +/- 25.6 microU/IEQ; P < 0.02), although islets of both groups responded with high stimulation indices (>6). These results indicate that the addition of BPS to the collagenase solution increases the recovery of viable islets, and improves beta cell function.

Animals↗
PubMed2001

Prolongation of islet allograft survival in mice by combined treatment with pravastatin and low-dose cyclosporine.

Pravastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, is known to have suppressive effects on immune and inflammatory cells. We have previously shown in mice and dogs that this agent prevents primary nonfunction of islet iso- and autografts by reducing inflammation at the graft site. The present study was designed to further investigate whether pravastatin has a synergistic effect with cyclosporine (Cs) to prolong islet allograft survival in mice. Unpurified 3000 BALB/c newborn islets were transplanted under the renal capsule of a streptozotocin-diabetic C57BL/6 mouse. Pravastatin and Cs were administered for 10 days starting on the day of grafting (day 0). Five groups were set up based on the treatment protocol: group 1, treatment with 40 mg/kg pravastatin; group 2, 30 mg/kg Cs; group 3, 50 mg/kg Cs; group 4, 40 mg/kg pravastatin and 30 mg/kg Cs; group 5, vehicle alone. Graft survival was indicated by blood glucose levels sustained at <200 mg/dl, and graft rejection by >250 mg/dl for 2 consecutive days. Hyperglycemia persisted in six of the eight (75%) mice and grafts were rejected in 3.6 +/- 0.5 days (mean +/- SD) in group 5. In group 1, grafts were also rejected in 3.8 +/- 0.8 days, but blood glucose was transiently <200 mg/dl in three of the five mice. Despite Cs, grafts were rejected between 7 and 15 days (10.3 +/- 2.4 days) in group 2. Among six mice in group 3, one maintained euglycemia for >60 days, the other rejected the graft on day 15, and the remaining four died with functioning grafts between 9 and 13 days due to Cs toxicity. A combination of a low dose of Cs and pravastatin (group 4) prolonged graft survival for >19 days in five of the eight mice, and for 7-13 days in the remaining three mice. Histological examination of the grafts in this group showed significantly reduced local inflammation. Results indicate a synergistic effect of pravastatin and Cs on prevention of islet allograft rejection.

Animals↗
PubMed2000

Validity of cadmium concentration in rice as the "dose" of the dose-response relationship between cadmium intake and renal dysfunction.

It is well known that cadmium (Cd) causes renal dysfunction such as increase of beta(2)-microglobulin excretion into urine. Although Cd in rice seems to be one of the largest sources of total Cd intake in Japan, there are very few studies that have epidemiologically clarified the relationship between Cd concentration in rice (Cd-R) and renal dysfunction, because such studies are basically ecological studies, in which confounding factors are difficult to take into consideration. To derive safety levels for foodstuff from Cd-R, it is essential to evaluate the effect of confounding factors. Thus, we investigated the dose-response relationship between renal dysfunction and not only Cd-R but also confounding factors, and we tried to determine whether Cd-R is an adequate indicator of "dose" in the dose-response relationship between Cd intake and renal dysfunction. In 1971, Cd-R data were obtained from rice samples collected by the Environment Agency, Government of Japan in the Fuchu area of Toyama Prefecture, which is known as a place where many itai-itai disease patients were found, and medical data were collected during 1979-1984 by Toyama Prefecture. First, the dose-response relationship between Cd-R and renal dysfunction was analyzed using the data from the Fuchu area. Second, to investigate the effect of confounding factors, analysis using the data from both the Fuchu area and an unpolluted area with environmental factors different from those of the Fuchu area was performed. The results showed that the cause of renal dysfunction could not be explained by Cd-R alone, and confounding factors were not negligible. Although it is difficult to clarify precisely the confounding factors from the available data, it is concluded that deriving a safety level for foodstuffs using only the Cd-R level as a reference is not appropriate.

Aged↗
PubMed2000

Loss of heterozygosity on chromosome 6p21.2 as a potential marker for recurrence after radiotherapy of human cervical cancer.

Cervical carcinomas develop as a result of multiple genetic alterations, and specific alterations lead to specific clinical behavior. However, the effect of such alterations on the recurrence of cervical cancer after radiotherapy remains unknown. Chromosome arm 6p is one of those most frequently involved in a loss of heterozygosity (LOH) in patients with cervical carcinoma. The aim of this study was to identify the correlation between the LOH on chromosome 6p21.2 and the recurrence of cervical cancer after radiotherapy. A total of 62 patients with cervical cancer (stage I, 4 patients; stage II, 9 patients; stage III, 37 patients; and stage IV, 12 patients) were included in this study. All patients were treated with definitive radiotherapy. We analyzed specimens from the tumors and venous blood of all patients. Tumors and normal DNA were analyzed by PCR for genetic losses at three polymorphic microsatellite loci (D6S276, D6S1624, and D6S1583). Chromosome 6p21.2 is involved in the LOH in 46.8% (29 of 62) of the informative carcinomas. Ten patients had a local recurrence, 4 had distant metastases, and 13 had both local recurrence and distant metastases after radiotherapy. To evaluate the relationship between the recurrence after radiotherapy and LOH on chromosome 6p21.2, we divided the patients into those with cancer recurrence (n = 27) and those without recurrence (n = 35). LOH on chromosome 6p21.2 was correlated with recurrence after radiotherapy (P = 0.006). The tumors in patients with recurrence were significantly larger than those in patients without recurrence (P = 0.003). However, there was no correlation between the sizes and stages of tumors and the LOH on chromosome 6p21.2. In addition, both overall survival and relapse-free survival were significantly worse for the patients with LOH as compared with those without LOH (P = 0.02 and P = 0.002, respectively). The results of this study suggest that LOH on 6p21.2 is correlated with recurrence of cervical carcinoma after radiotherapy.

Adult↗
PubMed1999

Improved human islet isolation by a tube method for collagenase infusion.

BACKGROUND: Collagenase infusion into the pancreatic duct is an essential step in human islet isolation. We developed a new method for ductal canulation and collagenese infusion. METHODS: A total of 53 pancreata were divided into two groups: group 1 (n=23), the new tube method, and group 2 (n=30), the standard angiocatheter method. In group 1, a polyethylene tube was inserted into the duct and pushed to the tail. The tail was first expanded, followed by expansion of the body and then the head, by pulling out the tube. RESULTS: Total islet number and number/g pancreas (mean+/-SE) were significantly higher in group 1 (481,123+/-43,218 and 8,010+/-722) (mean+/-SE) than in group 2 (300,974+/-35,122 and 5,090+/-515, P<0.01). Total islet equivalent number and islet equivalent number per gram pancreas were also significantly higher in group 1 (319,176+/-39,354 and 5,455+/-652) than in group 2 (202,022+/-23,331 and 3,722+/-468, P<0.04). Islet purity and fragmentation showed no differences between the groups. CONCLUSIONS: The tube method improved islet yields. We recommended this method for human islet isolation.

Catheterization↗
PubMed1999

Improved recovery of cryopreserved canine islets by use of beraprost sodium.

Cryopreservation of pancreatic islets provides many advantages for clinical transplantation. Unfortunately, the freezing and thawing processes lead to a significant loss of islets. In this study, an attempt was made to increase the yield and viability of islets after cryopreservation and thawing. By using canine islets, we evaluated whether beraprost sodium (BPS), a stable prostacyclin analog, protects islets during the freeze-thaw processes and improves the recovery of frozen-thawed islets. Canine islets were frozen and thawed by the procedures used routinely for storage of human islets. In this study, we deliberately used islets of lower purity (60+/-3.6%), which is undesirable for cryopreservation. The recovery of viable islets after thawing is poorer with islets of lower purity than with highly purified islets. BPS was added to both the cryopreservation solutions containing dimethyl sulfoxide (DMSO) and the thawing solution containing sucrose. After thawing, the islet recovery (islet number after thawing divided by islet number before freezing) was 71.1+/-12.7% with 1 nM BPS, 77.8+/-5.6% with 10 nM BPS, 79.3+/-6.7% with 100 nM BPS, and 69.2+/-7.2% in control preparations without BPS. Islet viability assessed by supravital staining was 57.5+/-5.6%, 64.7+/-7.0%, 67.5+/-6.5%, and 57.7+/-4.9% with 1 nM, 10 nM, and 100 nM BPS and controls, respectively. Both islet recovery and viability were significantly better with 10 nM and 100 nM BPS than with the controls (p<0.03). After 3 days in culture, islet numbers in the 10 nM and 100 nM BPS groups were significantly higher and showed better insulin-release responses than those from the 1 nM BPS and control groups. Histologically, islet structure was well preserved in the 10 nM and 100 nM BPS groups, whereas many islets of the control group were smaller and fragmented. Electron microscopic examination revealed that 10 nM and 100 nM BPS preserved the microstructure of islet cells, and signs of apoptosis or necrosis were rare. It was concluded that BPS improved the recovery and viability of canine islets after cryopreservation and thawing. BPS would be a useful agent for improving the recovery of cryopreserved human islets for clinical transplantation.

Animals↗
PubMed1999

Effect of water, saliva and blood contamination on bonding of metal brackets with a 4-META/MMA/TBB resin to etched enamel.

PURPOSE: To investigate the influence of contamination by water, human saliva, and blood on the bonding of metal brackets with a 4-META/MMA/TBB resin to etched enamel. MATERIALS & METHODS: For compressive shear bond strength measurements, the surfaces of bovine enamel were prepared either by etching with 37% phosphoric acid solution for 10, 30, or 60 s and then dried with oil-free compressed air for 10 s, or by contaminating with water, human saliva, and blood. Brackets were applied with Super Bond under loads of 200, 400, or 600 g. The bonded samples were immersed in water for 1 d or thermo-cycled for 500 cycles, and the mean shear bond strengths were compared using two-way ANOVA and Scheffé's multiple comparisons test at P = 0.05. RESULTS: The bond strengths to enamel etched for 60 s were independent of the variable load, regardless of the type of contamination. A short etching duration provided higher bond strengths than extended etching of samples contaminated with saliva and blood. The bond strengths to enamel etched for 10 s after thermal stress and immersion in water were from 11.4 to 30.4 MPa. The samples contaminated by saliva showed the lowest bond strength, and thermal stress did not reduce the bond strengths.

Acrylic Resins↗
PubMed1998

Prevention of primary islet isograft nonfunction in mice with pravastatin.

BACKGROUND: Nonspecific inflammatory damage in the early stages of transplantation is the major cause of primary islet graft nonfunction. Using murine isografts, we attempted to prevent this islet graft damage by treating recipients with pravastatin (Pravacol), a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor. Nicotinamide was also tested to determine the synergistic effect of both agents. METHODS: Unpurified newborn BALB/c islets, ranging in number from 1800 to 2500, were transplanted into the left renal subcapsular space of a syngeneic adult mouse made diabetic with streptozotocin. Recipient mice were divided into the following four groups, based on treatment protocols: treatment with 40 mg/kg pravastatin (group 1), 500 mg/kg nicotinamide (group 2), 40 mg/kg pravastatin and 500 mg/kg nicotinamide (group 3), and vehicle alone (group 4). Pravastatin and nicotinamide were administered orally every day for 14 days, starting on the day of transplantation (day 0). Nonfasting blood glucose levels, urine glucose levels, and the intravenous glucose tolerance test were used to monitor the diabetic state. The reversal of diabetes was defined by normoglycemia and negative urine glucose maintained for more than 7 days. RESULTS: After islet transplantation, levels of blood and urine glucose were significantly lower in groups 1 and 3, compared with those in group 4. K-values of an intravenous glucose tolerance test performed on day 14 were significantly higher in groups 1 and 3 than those of group 4. Reversal of diabetes had occurred in 63% of mice in group 1 and 67% in group 3, levels that were higher than those in group 2 (17%) and group 4 (0%) (P<0.02, groups 1 and 3 vs. group 4). Histological examination of grafts, biopsied on day 21, revealed well preserved islets with little sign of inflammation in groups 1 and 3, whereas grafts in groups 2 and 4 contained broken, smaller islets surrounded by severe fibrosis and mononuclear cell infiltration. CONCLUSION: Our results in mice have shown the effectiveness of pravastatin for protecting islets from nonspecific inflammatory damage. Nicotinamide did not show a synergistic effect with pravastatin at the dosage used in this study. These results indicate that pravastatin may be a useful agent for clinical islet transplantation.

Animals↗