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We investigate the critical behavior of the two-dimensional spin-1 Baxter-Wu model in the presence of a crystal-field coupling Δ with the goal of determining the universality class of transitions along the second-order part of the transition line as one approaches the putative location of the multicritical point. We employ extensive Monte Carlo simulations using two different methodologies: (i) a study of the zeros of the energy probability distribution, closely related to the Fisher zeros of the partition function, and (ii) the well-established multicanonical approach employed to study the probability distribution of the crystal-field energy. A detailed finite-size scaling analysis in the regime of second-order phase transitions in the (Δ,T) phase diagram supports previous claims that the transition belongs to the universality class of the four-state Potts model. For positive values of Δ, we observe the presence of strong finite-size effects, indicative of crossover effects due to the proximity of the first-order part of the transition line. Finally, we demonstrate how a combination of cluster and heat-bath updates allows one to equilibrate larger systems, and we demonstrate the potential of this approach for resolving the ambiguities observed in the regime of Δ≳0.

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Survival and growth of the native oyster Crassostrea gasar along the juvenile and adult phases were evaluated in three different stocking densities [low (D), medium (2D) and high (3D)] and in two grow-out systems (fixed and floating system). The fixed system consisted of a rack made with PVC, fixed from the bottom with wood sticks. The floating system consisted of floating bags suspended by a rack made with PVC and maintained submerged from the seawater surface by eight floats. Survival and shell height of oysters cultured after 30, 60 and 90 days were registered in each phase and in each grow-out system. Results showed that the grow-out system did not affect survival and growth of C. gasar in the juvenile and adult phases. The tested densities affected the survival of oysters cultured over time in both phases but did not affect oyster growth. At times analyzed, it was observed positive growth in juvenile oysters grow after 90 days of culture. However, in the adult phase, no growth was observed after 90 days of culture. Oyster yield was higher in the density 3D, in both juvenile and adult phases. These findings contributed to the development of the oyster C. gasar culture.(AU)

A sobrevivência e o crescimento da ostra nativa Crassostrea gasar nas fases juvenil e adulta foram avaliados sob três diferentes densidades de estocagem [baixa (D), média (2D) e alta (3D)] e dois sistemas de engorda (fixo e flutuante). O sistema fixo consistiu em uma mesa de PVC, fixada na parte inferior com varas de madeira. O sistema flutuante consistiu em travesseiros flutuantes suspensos por uma mesa de PVC e mantidas submersas da superfície da água do mar por oito flutuadores. Registraram-se sobrevivência e altura da concha de ostras cultivadas após 30, 60 e 90 dias, em cada fase (juvenil e adulta) e em cada sistema (fixo e flutuante). Os resultados mostraram que o sistema de engorda não afetou a sobrevivência e o crescimento de C. gasar nas fases juvenil e adulta. As densidades testadas afetaram a sobrevivência das ostras ao longo do tempo, em ambas as fases, mas não afetaram o crescimento em altura. Nos tempos analisados, ostras juvenis apresentaram crescimento após 90 dias de cultivo. Porém, na fase adulta, não foi observado crescimento após 90 dias de cultivo. A produção de ostras, foi maior na densidade 3D, nas fases juvenil e adulta. Os presentes achados contribuíram para o desenvolvimento do cultivo da ostra C. gasar.(AU)

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Two different methods for isolation of islet of Langerhans on control of metabolic abnormalities of alloxan-induced diabetic rat were tested. Sixty rats were randomly assigned to four experimental groups: GI included 10 non-diabetic control rats, GII included 10 diabetic control rats, without treatment, GIII included 20 diabetic rats (10 inbred and 10 outbred rats) that received islet of Langerhans transplantation (ILT) using islet cells prepared by collagenase, and GIV included 20 diabetic rats (10 inbred and 10 outbred rats) submitted to ILT using islet cells prepared by nonenzymatic method. Clinical and laboratory parameters at beginning and 4, 7, 14, 21 and 30 days of follow-up were recorded. Outbred rats were immunosuppressed with cyclosporin A, diabetes was induced by e.v. alloxan administration, and islet cells were isolated from normal donor Lewis rats and injected into the portal vein. ILT corrected the body weight gain, polyuria, polydipsia, polyphagia, and the high levels of blood and urine glucose in 73.7% of rats treated by enzymatic method and in 64.7% of those ones treated by nonenzymatic method. However, there was no significantly difference between the two methods (P > 0.50). We did not also observe significantly difference between the two methods when ILT was performed either in inbred or outbred rats. We concluded that ILT performed by nonenzymatic method may be an alternative treatment for diabetes due to be less expensive and to have possible advantages in the isolation process.

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Acarbose is a competitive inhibitor of the intestinal alpha-glycosidases, that can delay absorption of intestinal carbohydrates causing their malabsorption. In the present paper we studied the effects of insulin, acarbose and their association on glomerular basement membrane thickening in alloxan-diabetic rats. Twenty-five male and female Wistar rats, approximately 3 months old at the beginning of the experiment, were assigned randomly to each of five experimental groups: normal control rats, alloxan-diabetic control rats, alloxan-diabetic rats treated with acarbose, alloxan-diabetic rats treated with insulin, and alloxan-diabetic rats treated with insulin plus acarbose. Alloxan was administered in a single i.v. dose of 442 mg/kg body weight. Insulin was given subcutaneously at doses of 18 to 30 IU/kg corrected daily on the basis of glycosuria and ketonuria. Acarbose was given mixed with rat chow in a dose of 50 mg/100 g chow. Body weight, water and food intake and diuresis, as well as blood and urine glucose were determined after 1, 3, 6, 9, and 12 months of treatment. Glomerular basement membrane (GBM) thickening was determined by electron microscopy at the same times. Clear clinical and laboratory signs of severe diabetes, with blood glucose levels above 200 mg/dl and urine glucose above 3000 mg/dl, were observed in all alloxan-diabetic control rats, in all periods of follow-up, whereas administration of insulin or acarbose reduced the blood glucose levels of treated groups. The most satisfactory control of blood and urine glucose was observed in animals treated with both insulin and acarbose. However, diarrhea was observed in diabetic rats treated with acarbose associated or not with insulin. GBM thickening was correlated with age in all groups. Beginning at six months after diabetes induction, the GBM of untreated diabetic rats was significantly thicker (mean +/- SEM, 4.446 +/- 0.45 mm) than that of normal rats (2.977 +/- 0.63mm). Both insulin and acarbose prevented GBM thickening and their combination induced thickening similar to the age dependent thickening observed for normal rats of the same age. We conclude that acarbose when combined with insulin may be a good option in the control of diabetes and its renal complications.

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Acarbose is a competitive inhibitor of the intestinal alpha-glycosidases, that can delay absorption of intestinal carbohydrates causing their malabsorption. In the present paper we studied the effects of insulin, acarbose and their association on glomerular basement membrane thickening in alloxan-diabetic rats. Twenty-five male and female Wistar rats, approximately 3 months old at the beginning of the experiment, were assigned randomly to each of five experimental groups: normal control rats, alloxan-diabetic control rats, alloxan-diabetic rats treated with acarbose, alloxan-diabetic rats treated with insulin, and aloxan-diabetic rats treated with insulin plus acarbose. Alloxan was administered in a single iv dose of 42 mg/kg body weight. Insulin was given subcutaneously at doses of 18 to 30 IU/kg corrected daily on the basis of glycosuria and ketonuria. Acarbose was given mixed with rat chow in a dose of 50 mg/100 g chow. Body weight, water and food intake and diuresis, as well as blood and urine glucose were determined after 1, 3, 6, 9, and 12 months of treatment. Glomerular basement membrane (GBM) thickening was determined by electron microscopy at the same times. Clear clinical and laboratory signs of severe diabetes, with blood glucose levels above 200 mg/dl and urine glucose above 3000 mg/dl, were observed in all alloxan-diabetic control rats, in all periods of follow-up, whereas administration of insulin or acarbose reduced the blood glucose levels of treated groups. The most satisfactory control of blood and urine glucose was observed in animals treated with both insulin and acarbose. However, diarrhea was observed in diabetic rats treated with acarbose associated or not with insulin, GBM thickening was correlated with age in all groups. Beginning at six months after diabetes induction, the GBM of untreated diabetic rats was significantly thicker (mean + 4.446 + 0.45 mm) than that of normal rats (2.977 + 0.63 mm). Both insulin and acarbose prevented GBM thickening and their combination induced thickening similar to the age-dependent thickening observed for normal rats of the same age. We conclude that acarbose when combined with insulin may be a good option in the control of diabetes and its renal complications.

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In this study we present the technical details, adaptations and modifications of the original procedure of pancreaticoduodenal transplantation in rats described by Lee et al. in 1972. We also present the results and technical failures observed in a follow-up of 12 years. From March, 1982 to December, 1994, we performed in the Laboratory of Surgical Technique and Experimental Surgery of Faculty of Medicine, Botucatu-UNESP, Brazil, 665 duodenopancreatectomies in donor rats and 592 surgeries for revascularization of the pancreatic graft in recipient animals. The observed percentage of technical failures in donor rats was 11% due to bleeding and/or vascular complications, irregular flushing of the graft with saline and respiratory insufficiency. In recipients of grafts, we observed a percentage of technical failures of 22.5% due to porto-caval thrombosis, vascular bleeding, pancreatitis and graft ischemia. In both surgeries, the successful results are directly related to the technical performance of the surgeon and the cares in the postoperative period.

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Sixty outbred Wistar rats were randomly assigned to five experimental groups: GI-10 non-diabetic control rats; GII-10 untreated diabetic control rats; GIII-10 diabetic rats treated with retard porcine insulin; GIV-20 diabetic rats that received pancreaticoduodenal transplantation (PDT) from normal donor rats; GV-10 diabetic rats submitted to islet of Langerhans transplantation (ILT) into the portal vein. The animals were housed in metabolic cages for six periods of 24 hours during 30 days and body weight, water and food intake, urine output, blood and urinary glucose were recorded. Diabetes was induced by I.V. administration of Alloxan (42 mg/kg of body weight); PDT was performed by microsurgical techniques and islets were prepared without enzymes. To prevent rejection. Cyclosporin A (10 mg/kg of body weight) was utilized in transplanted rats. PDT consistently and significantly (p < 0.05) improved the metabolic abnormalities of the diabetic rats, by restoring the body weight gain, and immediate relief of polydipsia, polyphagia, polyuria, hyperglycemia and glucosuria observed in pre-treatment period. PDT was more effective than ILT and this over insulin therapy on control of the diabetic state. However, the observed complications in GIV and GV, due to surgery and immunosuppression, should be analysed for the real benefits of the alternative therapy can be superior to eventual fails to the conventional therapy with insulin.

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1. Forty-five outbred Wistar rats were randomly assigned to three experimental groups: GI, 10 non-diabetic control rats; GII, 10 alloxan-diabetic control rats; GIII, 25 alloxan-diabetic rats which received pancreaticoduodenal transplantation (PDT) from normal Wistar donor rats and were immunosuppressed with cyclosporin A (Cy-A), 10 mg kg body weight-1 day-1, administered intraperitoneally for 30 days. 2. In parallel, 15 alloxan-diabetic inbred Wistar rats received isogeneic PDT from normal Wistar donor rats. 3. Cy-A prevented graft rejection in the 15 surviving animals in group III. These observations were confirmed by clinical and biochemical parameters (body weight, urine output, water and food intake, blood and urinary glucose and plasma insulin) and by histology and immunohistochemistry of the pancreas. 4. However, Cy-A was associated with 60% of the infectious complications in transplanted rats leading to 40% mortality. Pulmonary infections were the main cause of death. There were no side effects of immunosuppression on the pancreas. Infections were not significant in inbred rats submitted to PDT.

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Outbred Wistar rats were randomly assigned to three experimental groups: GI, 10 nondiabetic control rats; GII, 10 alloxan-diabetic control rats; GIII, 25 alloxan-diabetic rats that received pancreaticoduodenal transplantation (PDT) from normal donor Wistar rats and were immunosuppressed with cyclosporin A. For 7 prior and 4, 7, 14, 21, and 30 days posttransplantation (during which the animals were housed in metabolic cages for periods of 24 hours) body weight, water and food intake, urine output, blood and urinary glucose, plasma insulin, and glucagon were recorded. These parameters were also concurrently recorded for diabetic and nondiabetic control rats. Animals were sacrificed after 30 days and histological and immunohistochemical studies of the pancreas were performed. Pancreatic transplants consistently and significantly improved the metabolic abnormalities of the diabetic rat (P less than 0.01) by restoring body weight gain, and by immediate relief of hyperglycemia, glucosuria, polyuria, polydipsia, and also the low levels of plasma insulin. The plasma glucagon, elevated in diabetic control rats, did not change after transplant.

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1. Forty-five outbred Wistar rats were randomly assigned to three experimental groups: GI, 10 non-diabetic control rats; GII, 10 alloxan-diabetic control rats; GIII, 25 alloxan-diabetic rats which received pancreaticoduodenal transplantation (PDT) from normal Wistar donor rats and were immunosuppressed with cyclosporin A (Cy-A), 10 mg kg body weight-1 day-1, administered intraperitoneally for 30 days. 2. In parallel, 15 alloxan-diabetic inbred Wistar rats received isogeneic PDT from normal Wistar donor rats. 3. Cy-A prevented graft rejection in the 15 surviving animals in group III. These observations were confirmed by clinical and biochemical parameters (body weight, urine output, water and food intake, blood and urinary glucose and plasma insulin) and by histology and immunohistochemistry of the pancreas. 4. However, Cy-A was associated with 60% of the infectious complications in transplanted rats leading to 40% mortality. Pulmonary infections were the main cause of death. There were no side effects of immunosuppression on the pancreas. Infections were not significant in inbred rats submitted to PDT

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The aim of this study was to test the application and value of electrocorticography (ECG) in the early diagnosis and characterization of electrocorticograms changes on experimental fulminant hepatic failure (FHF). Our material was composed of two groups of guinea pigs: a) ethanolamine group--42 animals with FHF induced by intrabiliary injection of 2.5 ml of monoethanolamine oleate; b) control group--10 animals submitted to intrabiliary injection of 2.5 ml of saline. Electrocorticograms recordings were taken in both groups with the electrodes implanted on the parieto-occipital regions of the skull. The hepatic failure was characterized by clinical manifestations, serum biochemical tests and histopathological findings. In the early hepatic coma the electrocorticograms could not be unequivocally distinguished from normal pattern, and alpha rhythm was recognizable in most animals. With further deterioration of the clinical condition the tracing showed progressive slowness of the normal rhythm, increased voltage and triphasic waves followed by suppression of electrical activity preceding the animal death. The electrocorticography was not suitable for the early diagnosis of hepatic coma, since the ECG alterations became evident only in overt coma. However the method could be useful for the characterization of cerebral disorders and the study of the pathogenesis of fulminant hepatic failure.

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Com o objetivo de estudar a necrose isquemica da pequena curvatura gastrica, apos vagotomia gastrica proximal (VGP), foram operados 36 caes distribuidos por sorteio em dois grupos experimentais: Grupo 1 VGP e Grupo 2 - VGP e traumatismo da parede gastrica. Este tipo de traumatismo foi realizado atraves de uma ligadura, englobando a parede gastrica, com fio de algodao no. 10. Pelos resultados obtidos verificamos que a desvascularizacao determinada pelas ligaduras dos pediculos vasculonervosos, na tecnica de VGP, conserva a irrigacao necessaria a nutricao e manutencao dos tecidos da pequena curvatura gastrica. As ligaduras englobando a parede gastrica podem determinar desde necrose parcial ou total, com perfuracao e peritonite, ate lesoes semelhantes a ulcera cronica. Nos casos de necrose parcial da parede gastrica podem ocorrer tambem lesoes da mucosa gastrica tais como: exulceracao, sufusao hemorragica e convergencia de pregas da mucosa para o local de traumatismo

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An appropriate animal model of acute fulminant hepatic failure was developed in the guinea pig by he intrabiliary administration of monoethanolamine oleate. The animals were assigned in two experimental groups: 1) ethanolamine group - 42 guinea pigs that received intrabiliary 2,5 ml injection of monoethanolamine oleate; 2) control group - 18 guinea pigs subjected to intrabiliary 2,5 ml administration of saline. The intrabiliary administration of the ethanolamine oleate resulted in massive liver injury with 85,9% of hepatic coma during the first 96 hr. The liver damage was characterized by clinical manifestations (anorexia, increasing stupor, muscle wasting and deep coma), serum biochemical tests (elevations of serum transaminases, bilirubins , alkaline phosphatase), studies of blood coagulation (prothrombin and partial thromboplastin times were markedly prolonged and the concentration of fibrinogen decreased) and histopathological findings (massive hepatic necrosis). This animal model appears promising for future studies of the pathogenesis and treatment of acute hepatic failure.

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Com o objetivo de produzir um modelo experimental de insuficiencia hepatica aguda (IHA) no cobaio, foram empregados 60 cobaios distribuidos nos seguintes grupos experimentais: a) Grupo Etanolamina - 42 animais submetidos a injecao de 2,5 ml de oleato de monoetanolamina no ducto biliar comun; b) Grupo Controle - 18 animais, nos quais foram injetados 2,5 ml de solucao de NaCI a 0,9% no ducto biliar comum. Foram utilizados para a caracterizacao da IHA os seguintes parametros: quadro clinico, exames laboratoriais (bioquimicos, hematologicos e teste de coagulacao sanguinea) e exame anatomopatologico. A injecao de etanolamina produziu um modelo de insuficiencia hepatica aguda, com a ocorrencia de coma hepatico bem definido em 85,5% dos cobaios nas primeiras 96 horas de evolucao A IHA foi caracterizada pelo quadro clinico tipico de falencia hepatica, alteracoes dos exames bioquimicos (elevacao das bilirrubinas, transaminases e fosfatase alcalina), pelos disturbios da coagulacao sanguinea (alongamento dos tempos de protrombina e tromboplastina parcial ativada e queda do fibrinogenio plasmatico) e pela necrose hepatica macica constatada no exame anatomopatolofico.O modelo experimental desenvolvido pode ser util para o estudo da fisiopatologia da insuficiencia hepatica e para a pesquisa de novos metodos terapeuticos do coma hepatico

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E apresentado um novo modelo de insuficiencia hepatica aguda no cobaio, produzido pela injecao intrabiliar de solucao esclerosante. Foram empregados 100 cobaios distribuidos em dois grupos experimentais: 1) Grupo Solucao Esclerosante - 70 animais submetidos a injecao no ducto biliar comum de uma solucao constituida por fenol, acido acetico glacial, glicerina e agua bidestilada na dose de 1 ml. 2) Grupo Controle - 30 animais, noa quais foram injetados 1 ml de solucao de NaCl a 0,9%.A injecao da solucao esclerosante no ducto biliar produziu em 52,9% dos cobaios insuficiencia hepatica aguda caracterizada por: a) quadro clinico bem definido, com evolucao para o coma hepatico de instalacao lenta e longa duracao: b) alteracao dos exames bioquimicos e dos testes de coagulacao sanguinea; c) alteracoes anatomo-patologicas. O modelo experimental desenvolvido pode ser util para o estudo dos mecanismos fisiopatologicos envolvidos na insuficiencia hepatocelular e para a avaliacao de novos metodos para o tratamento do coma hepatico

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