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Biomedical subjects

S Arita

Publications and source records attributed to S Arita.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1998

Aneurysm of a persistent sciatic artery.

We report a case of an aneurysm of a persistent sciatic artery which caused buttock pain. Preoperative diagnosis is very difficult. However, awareness of the presence of this rare embryonic abnormality is important, especially in elderly persons with atherosclerotic changes. Sagittal magnetic resonance imaging (MRI) was very useful in reaching this diagnosis.

Aged↗
PubMed1997

A two-step digestion process and LAP-I cold preservation solution for human islet isolation.

Pancreatic islet transplantation has a high potential for treating diabetes mellitus, but long-lasting insulin independence has not been achieved in type I diabetic patients. In order to obtain better results, improvement is needed in many areas. The first area is the islet isolation process. The requirements for an islet isolation method are: 1) to produce a maximum number of healthy islets without demanding a high quality of donor pancreas; 2) to be able to perform the procedure with fewer numbers of personnel who may be without extensive skills and expertise; and 3) to lower isolation costs. In order to achieve these objectives, we have made two important modifications to the isolation process. One is the development of a new preservation solution, LAP-I and the other is the use of a two-step process for pancreas digestion, involving a short warm collagenase digestion, followed by cold mechanical digestion without collagenase. We also use a clear plastic digestion chamber in order to visualize the process. The chamber cover is designed to facilitate frequent removal of digested tissue fragments. The overall procedure is simple and straightforward, requires less manpower and is cost effective. Our procedure is described in detail, and its advantages are discussed.

Adenosine↗
PubMed1996

Immunohistochemical detection of estrogen and progesterone receptors performed with an antigen-retrieval technique on methacarn-fixed paraffin-embedded breast cancer tissues.

Immunohistochemical detection of estrogen and progesterone receptors (ER and PgR, respectively) was performed in 67 cases of Japanese female invasive breast carcinoma on methacarn-fixed paraffin-embedded sections using monoclonal antibodies against ER (1D5) and PgR (10A9) with an antigen-retrieval technique based on microwave exposure in citrate buffer solution. Staining localized in nuclei and specimens containing > or = 20% specifically stained tumor cell nuclei were considered ER- or PgR-positive; the positive rate was 37% (25/67) for ER and 45% (30/67) for PgR. The immunohistochemical (IHC) results were compared with cytosolic receptors obtained from tissue homogenates as measured by dextran-coated charcoal (DCC) assay, in which tumors were considered ER- and/or PgR-positive when receptor concentration was greater than 3 or 5 fmol/mg cytosolic protein, respectively, and agreement between the two methods was 71.6% for ER and 80.6% for PgR. The sensitivity and specificity were 53.5 and 91.7% for ER-IHC, and 77.4 and 83.3% for PgR-IHC, respectively. In relation to age of the patient and stage of the cancer, ER immunoreactivity correlated with patient's age (> or = 55 vs 55, P = 0.032), and proportionally increased with aging (P = 0.0084) using the Kruskal-Wallis statistics. PgR-immunoreactivity correlated with nodal involvement (P = 0.031) by the TNM system. However, no correlations were found between the results of the DCC assay and any of the clinical parameters examined. Thus, immunohistochemical assay may provide valuable information in predicting prognosis and response to endocrine therapy.

Acetates↗
PubMed1996

Modulating autoimmune responses to GAD inhibits disease progression and prolongs islet graft survival in diabetes-prone mice.

In nonobese diabetic (NOD) mice, beta-cell reactive T-helper type 1 (Th1) responses develop spontaneously and gradually spread, creating a cascade of responses that ultimately destroys the beta-cells. The diversity of the autoreactive T-cell repertoire creates a major obstacle to the development of therapeutics. We show that even in the presence of established Th1 responses, it is possible to induce autoantigen-specific anti-inflammatory Th2 responses. Immune deviation of T-cell responses to the beta-cell autoantigen glutamate decarboxylase (GAD65), induced an active form of self-tolerance that was associated with an inhibition of disease progression in prediabetic mice and prolonged survival of syngeneic islet grafts in diabetic NOD mice. Thus, modulation of autoantigen-specific Th1/Th2 balances may provide a minimally invasive means of downregulating established pathogenic autoimmune responses.

Adoptive Transfer↗