Two-dimensional dilute Baxter-Wu model: Transition order and universality.

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.

Growth and survival of the native oyster Crassostrea gasar cultured under different stocking densities in two grow-out systems in tropical climate / [Crescimento e sobrevivência da ostra nativa Crassostrea gasar cultivada em diferentes densidades em dois sistemas em clima tropical]

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)

Prepubertal goat oocytes from large follicles result in similar blastocyst production and embryo ploidy than those from adult goats.

Developmental competence of oocytes from prepubertal females is lower than those from adult females. Oocyte development competence is positively related to follicular diameter. Most of the follicles of prepubertal goat ovaries are smaller than 3 mm. The aim of this study was to compare oocytes of two follicle sizes (< 3 mm and ≥ 3 mm) from prepubertal goats with oocytes from adult goats in relation to their in vitro production and quality of blastocysts. Oocytes from prepubertal goats were obtained from slaughterhouse ovaries and selected according to the follicle diameter whereas oocytes from adult goats were recovered in vivo by LOPU technique without prior selection of follicle size. COCs were IVM for 27 h, IVF at the conventional conditions with fresh semen and presumptive zygotes were cultured in SOF medium for 8 days. Blastocysts obtained were vitrified and after warming their blastocoele re-expansion and the ploidy by FISH technique were assessed. We found significant differences between blastocysts yield of oocytes recovered from follicles smaller than 3 mm of prepubertal goats compared to those from adult goats (5.45% vs 20. 83%, respectively) however, these differences disappear if oocytes were recovered form large follicles (18.07%). A total of 28 blastocysts were analysed and 96.43% showed mixoploidy. Age did not affect the number of embryos with abnormal ploidy or blastocyst re-expansion after warming. Furthermore, the percentage of diploid blastomeres per embryo was similar in the 3 groups studied, adult, prepubertal from follicles ≥ 3 mm and < 3 mm (68.6%, 80.8% and 73.6%, respectively). In conclusion, IVP of blastocysts coming from follicles larger than 3 mm of goats 45 days old were not different to the blastocysts produced from adult goats, both in terms of quantity and quality.

Oocyte secreted factors improve embryo developmental competence of COCs from small follicles in prepubertal goats.

Oocytes secrete soluble paracrine factors called Oocyte Secreted Factors (OSFs) which regulate the cumulus cell phenotype. Follicle populations in ovaries from prepubertal females have smaller diameters than their adult counterparts. Oocytes from small follicles are less competent than those from large follicles. The aim of this study was to investigate, in prepubertal goats, the effect of OSFs secreted by denuded oocytes (DOs) from small (<3 mm) or large (>or=3 mm) follicles during IVM on embryo development and the blastocyst quality of cumulus-oocyte complexes (COCs) from small follicles and to determine if GDF9 participates in this process. Treatment groups were: (A) COCs non selected by their follicle size (control group); (B) cumulus oocytes complexes from small follicles (SFCOCs), (C) cumulus oocytes complexes from small follicles co-cultured with denuded oocytes from small follicles (SFCOCs + SFDOs), and (D) cumulus oocytes complexes from small follicles co-cultured with denuded oocytes from large follicles (SFCOCs + LFDOs). The effect of the addition of kinase inhibitor SB-431542, which antagonizes GDF9, was tested in A, C, and D treatment groups. Co-cultured SFCOCs with SFDOs or LFDOs significantly augmented the blastocyst rate in comparison to SFCOCs alone (15.77%, 17.39% vs. 10.31%, respectively). Blastocysts from SFCOCs + LFDOs group showed higher rates of tetraploid nuclei than blastocysts from SFCOCs and the control group (14.43% vs. 5.45% and 5.24%, respectively; P < 0.05). However, we did not observe differences in the hatching rate, mean cell number or embryo cryotolerance (P > 0.05) between the four treatment groups. The addition of SB-431542 during IVM did not have any effect on blastocyst rate (P > 0.05). In conclusion, in prepubertal goats, COCs with a low embryo developmental competence as a consequence of follicle size can be improved by coculturing them with denuded oocytes from both small and large follicles. GDF9 does not seem play a role in this improvement.

Effect of follicle diameter on oocyte apoptosis, embryo development and chromosomal ploidy in prepubertal goats.

The aim of this study was to assess the following parameters in prepubertal goat oocytes of different follicle diameter (> or =3 mm, <3 mm, control): oocyte diameter, early (Annexin-V) and late (TUNEL) apoptosis, embryo development and chromosomal ploidy of these blastocysts using Fluorescence In Situ Hybridization (FISH). Before in vitro maturation, oocytes were measured and stained with Annexin-V or TUNEL. The rest of the oocytes were matured, fertilized, and cultured in vitro for 8 days. Oocytes from follicles of > or =3 mm showed greater mean oocyte diameter (128.27 +/- 7.20 microm vs. 125.35 +/- 7.59 microm), higher percentages of TUNEL positive (42.86 vs. 24.23%), higher cleavage (47.85 +/- 3.98 vs. 23.07 +/- 2.44 %) and blastocyst rates (19.77 +/- 3.04 vs. 4.11 +/- 1.10 %) than oocytes from follicles of <3 mm.. Blastocyst mean cell numbers did not show differences between follicular groups (123.83 +/- 49.62 vs. 104.29 +/- 36.09 for follicles of > or =3 mm and <3 mm, respectively). A total of 54 blastocysts with 7084 nuclei were hybridized with specific probes to chromosomes X and Y. Ninety-eight percent (98%) of the embryos presented at least one cell carrying an abnormal number of chromosomes, but 78% of them presented less than 25% of chromosomal abnormal cells. No differences in the percentage of blastocysts with abnormal ploidy were found in embryos produced from oocytes of different follicle diameter.

Effect of the apoptosis rate observed in oocytes and cumulus cells on embryo development in prepubertal goats.

Oocyte quality is the main factor that determines blastocyst yield; any factor that could affect it, such as apoptosis, could impair subsequent embryonic development. Our aim was to investigate the incidence of apoptosis in prepubertal goat oocytes and cumulus cells, assessed by Annexin-V staining and TUNEL assay, and their effect on embryo development. Oocyte-cumulus complexes (COCs) from slaughtered females were collected and classified depending on COC morphology as: Healthy (H) and Early Atretic (EA). Each one of these groups was classified depending on oocyte diameter: A: 110-125microm, B: 125-135microm and C: >135microm. The COCs were IVM for 27h, IVF with fresh semen and IVC for 8 days after insemination. Apoptosis analyses were performed before and after maturation. Annexin-positive oocytes decreased with diameter in the EA class (immature oocytes: A: 42.6%; B: 30.3%; C: 21%; IVM-oocytes: A: 17.5%; B: 4.8%; C: 0%), while TUNEL assay showed a decrease of apoptosis in the largest oocytes before and after IVM only in Healthy oocytes (immature oocytes: A: 51.5%; B: 43.3%; C: 12.1%; IVM-oocytes: A: 31.7%; B: 12%; C: 0%). Blastocyst rate increased with increasing oocyte diameter, and it was higher in H than in EA oocytes (Healthy; A: 0%; B: 5.3%; C: 14.4%; Early atretic: A: 0.3%; B: 4.1%; C: 5.1%). Oocyte diameter and COC morphology had no effect on the percentage of apoptosis in blastocyst cells. In conclusion, oocyte developmental competence in prepubertal goats is influenced by oocyte diameter and COC morphology.

Prognostic value of sperm fluorescence in situ hybridization analysis over PGD.

BACKGROUND: Sperm aneuploidy screening is now widely used as a counseling tool before performing a PGD cycle in infertile patients. The goal of this study was to determine whether sperm aneuploidy has a direct influence on embryo chromosomal abnormalities. METHODS: Two groups were set up: (i) study group consisting of 13 oocyte-donation PGD cycles from males with normal karyotype and a previous altered sperm fluorescence in situ hybridization (FISH) result and (ii) control group including nine cycles of PGD for X-linked disease with no fertility problems and maternal age <36 years. Sperm samples and Day 3 embryos were evaluated using FISH for chromosomes X, Y, 13, 18 and 21. RESULTS: A total of 179 embryos were analyzed: 91 embryos for the control group versus 88 for the study group. The study group presented more abnormal embryos than the control group (51.14% versus 35.16%; P = 0.0353). Patients from the study group were then classified according to sperm count. Oligozoospermic patients showed a much higher proportion of abnormal embryos compared with the control group (64.87% versus 35.16%; P = 0.0030). CONCLUSIONS: Sperm aneuploidy and diploidy screening seems to be an effective prognostic tool that would be useful in the reproductive genetic counseling of infertile couples, especially in oligozoospermic patients.

Effect of ICSI and embryo biopsy on embryo development and apoptosis according to oocyte diameter in prepubertal goats.

ICSI and embryo biopsy are routine methods used for assisted reproduction. However, their impact on embryo quality is still poor studied. Moreover, oocyte size is also a crucial factor for blastocyst production. In this study effect of oocyte size, ICSI and embryo biopsy was assessed in terms of incidence of apoptosis and blastocyst development. IVM-oocytes from prepubertal goats were fertilized by ICSI or IVF. Embryos obtained were divided depending on oocyte size, biopsied at day-4 post-insemination/injection and cultured for additional 4-5 days. Apoptotic cell number was assessed by TUNEL staining in day-4 embryos and blastocysts obtained. In each diameter group, ICSI did not affect embryo development, blastocyst cell number and embryo apoptotic grade in comparison to IVF. Embryo biopsy did not affect blastocyst rate and apoptotic cell number, but decreased blastocyst cell number (P=0.0018). Moreover, there was a negative relationship between blastocyst cell number and apoptotic grade (P<0.05). In conclusion, ICSI and embryo biopsy do not have negative effect on embryo quality and development. However, oocyte size has a positive relationship on blastocyst yield and quality.

[Islet of Langerhans transplantation. A comparative study of two different methods for isolating islet cells from rat pancreas]. / Transplante de ilhotas de Langerhans. Estudo comparativo entre dois métodos diferentes de isolamento de ilhotas do pâncreas do rato.

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.

Effect of long-term treatment with insulin and/or acarbose on glomerular basement membrane thickening in alloxan-diabetic rats.

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.

Effect of long-term treatment with insulin and/or acarbose on glomerular basement membrane thickening in alloxan-diabetic rats

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.

[Microsurgical pancreatoduodenal transplantation in rats. Technique and results following 12 years of investigation]. / Transplante pancreatoduodenal em ratos com microcirurgia. A técnica e os resultados após 12 anos de experimentação.

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.

[A comparative study of pancreatic-duodenal transplantation, islets of Langerhans transplantation, and insulin treatment, in the control of experimental diabetes in the rat]. / Estudo comparativo entre o transplante pancreato-duodenal, transplante de ilhotas de Langerhans e o tratamento com insulina, no controle do diabetes experimental no rato.

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.

Effects of cyclosporin A immunosuppression on pancreaticoduodenal transplantation in alloxan-diabetic rats.

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.

Metabolic effect of pancreaticoduodenal transplantation in diabetic rats.

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.

Effects of cyclosporin A immunosuppression on pancreaticoduodenal transplantation in alloxan-diabetic rats

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

[Electrocorticographic changes in acute experimental hepatic insufficiency]. / Estudo das alterações eletrocorticográficas na insuficiência hepática aguda experimental.

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.