RESUMO
In this research work, a material system formed of cadmium sulfide combined with chromium atoms was developed to evaluate the influence of chromium concentration on the optical, electrical, structural, and morphological properties of a precursor layer of CdS. It is possible to observe that the transmission spectra increased for all chromium concentrations analyzed. From X-ray diffractograms, we conclude more accurately that CdS presents a mixture of phases, including orthorhombic, hexagonal, and cubic. Furthermore, the impact of adding chromium results in variations in the intensity of two major peaks in the diffractograms and an anomalous shift in the CdS pattern. The calculated resistivities show an invariable behavior of 4.5 × 106 Ω cm. In addition, the bandgap values remain practically constant, with values of approximately 2.43-2.44 eV. The addition of chromium at different concentrations leads to surface morphology changes, as observed in SEM images.
RESUMO
This communication describes the first general biochemical, molecular and functional characterization of the venom from the Cuban blue scorpion Rhopalurus junceus, which is often used as a natural product for anti-cancer therapy in Cuba. The soluble venom of this arachnid is not toxic to mice, injected intraperitoneally at doses up to 200 µg/20 g body weight, but it is deadly to insects at doses of 10 µg per animal. The venom causes typical alpha and beta-effects on Na+ channels, when assayed using patch-clamp techniques in neuroblastoma cells in vitro. It also affects K+ currents conducted by ERG (ether-a-go-go related gene) channels. The soluble venom was shown to display phospholipase, hyaluronidase and anti-microbial activities. High performance liquid chromatography of the soluble venom can separate at least 50 components, among which are peptides lethal to crickets. Four such peptides were isolated to homogeneity and their molecular masses and N-terminal amino acid sequence were determined. The major component (RjAa12f) was fully sequenced by Edman degradation. It contains 64 amino acid residues and four disulfide bridges, similar to other known scorpion toxins. A cDNA library prepared from the venomous glands of one scorpion allowed cloning 18 genes that code for peptides of the venom, including RjA12f and eleven other closely related genes. Sequence analyses and phylogenetic reconstruction of the amino acid sequences deduced from the cloned genes showed that this scorpion contains sodium channel like toxin sequences clearly segregated into two monophyletic clusters. Considering the complex set of effects on Na+ currents verified here, this venom certainly warrant further investigation.
Assuntos
Venenos de Escorpião/química , Escorpiões/química , Animais , Linhagem Celular Tumoral , Fracionamento Químico , Cromatografia Líquida de Alta Pressão , Clonagem Molecular , Biblioteca Gênica , Gryllidae/efeitos dos fármacos , Camundongos , Dados de Sequência Molecular , Peptídeos/química , Peptídeos/genética , Peptídeos/isolamento & purificação , Filogenia , Ratos , Venenos de Escorpião/toxicidade , Escorpiões/genética , Alinhamento de Sequência , Análise de Sequência de DNA , Análise de Sequência de ProteínaRESUMO
1. Oxidative stress (OS) is a biological entity indicated as being responsible for several pathologies, including diabetes. Diabetes can also be associated with human cirrhosis. Portal hypertension (PH), a major syndrome in cirrhosis, produces hyperdynamic splanchnic circulation and hyperaemia. The present study was designed to investigate the occurrence of OS in prehepatic PH rat livers following the induction of diabetes. 2. Five groups of rats were used: control, sham operated, chronic diabetes (induced with a single dose of streptozotocin at 60 mg/kg, i.p.), prehepatic PH and chronic diabetic plus prehepatic PH. The occurrence of OS was determined in liver homogenates by measuring hydroperoxide-initiated chemiluminescence and the activity of anti-oxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase). 3. Prehepatic PH produced a significant increase in hydroperoxide-initiated chemiluminescence in the liver compared with control and sham-operated rats, whereas the liver in chronic diabetic rats showed no difference. However, chemiluminescence values decreased almost by 50% in the chronic diabetic plus prehepatic PH group. Concomitantly, the activities of the anti-oxidant enzymes in chronic diabetes, prehepatic PH and chronic diabetic plus prehepatic PH groups were decreased (P < 0.05 vs control and sham-operated groups). 4. Livers from the chronic diabetic group did not show any evidence of the occurrence of OS, whereas the prehepatic PH group showed the occurrence of OS. The association of PH and chronic diabetes resulted in a significant decrease in the occurrence of OS, which could be explained by an anti-oxidant response to an OS.
Assuntos
Diabetes Mellitus Experimental/metabolismo , Hipertensão Portal/metabolismo , Estresse Oxidativo/fisiologia , Animais , Catalase/metabolismo , Diabetes Mellitus Experimental/complicações , Modelos Animais de Doenças , Glutationa Peroxidase/metabolismo , Hipertensão Portal/complicações , Técnicas In Vitro , Fígado/enzimologia , Medições Luminescentes , Masculino , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismoRESUMO
A functional skeletal criterion, as an extension of the van der Klaauw's cranial theory, was adopted in the present study. The null hypothesis tested was: "The major skeletal components of the platyrrhine body grow linearly, regardless of their functional dependence to different demands." The acceptance of the hypothesis will imply that all Saimiri skeletal growth may be satisfactorily explained by independent variables in a single equation. The rejection will suggest that such skeletal growth patterns have to be explained by variables in several different equations, and perhaps these equations may vary with the effect of sex and undernutrition. Control and undernourished squirrel monkeys were radiographed monthly for 2 years; they were also measured; and their volumetric and morphometric neurocranial, facial, and pelvic indices were calculated. The curves that best described each of the 24-point sequences were obtained. Three main growth patterns were observed: 1) Simple linear (femur length for all groups, and pelvic index for control and undernourished females), for which the simple regression equation explained more than 95% of the variation; 2) Complex linear (pelvic index for control and undernourished males, and neurocranial and facial indices for all of the groups), for which more than 95% of the variation was explained by one of the four four-function type equations; and 3) Noncorrelated with age (neurofacial index for undernourished males, and pelviofemoral index for control females and undernourished males and females), which showed nonsignificant correlations with respect to age. The food intake and the oscillations of the environmental temperature might help to explain the undulating growth trajectory observed in the complex linear components.
Assuntos
Desenvolvimento Ósseo , Distúrbios Nutricionais/veterinária , Saimiri/crescimento & desenvolvimento , Animais , Feminino , Fêmur/crescimento & desenvolvimento , Estudos Longitudinais , Masculino , Modelos Teóricos , Pelve/crescimento & desenvolvimento , Saimiri/anatomia & histologia , Fatores SexuaisRESUMO
It has been demonstrated that, in the diabetic rat, pregnancy and lactation are severely altered: in this study, we have measured the size of Langerhans islets of rat pups, the offspring of experimental diabetic mothers and nondiabetic controls. Diabetes was induced through streptozotocin administration (dose, 60 mg/kg body wt.). This drug was injected in every animal; their blood sugar was measured 1 week later (Haemo-Glukotest, Boehringer Mannheim), and they were then separated into three groups according to their fasting blood sugar levels: (a) severe diabetics (above 16.5 mM/l); (b) mild diabetics (6.5-16.5 mM/l); and (c) nondiabetic normals. They received insulin therapy (2-4 I.U./day) as the mild diabetics exhibited a slightly higher than normal fasting blood sugar, and the diabetic ones, above 15 mM/l. The areas of Langerhans islets of pups were measured 1 and 5 days after parturition; pancreas sections were dyed (haematoxylin-eosin) and morphometry was then performed using a digitalized magnetic tabloid connected to a Zeiss Morphomat 30 (Kontron). On the first day after parturition, the pancreas section areas in pups from mildly and severely diabetic mothers were smaller than those in neonates from nondiabetic controls (P < 0.001). The areas in neonates from severely diabetic mothers showed a more intense decrease than those from mildly diabetic animals (P < 0.01). On day 5 after delivery, the areas of Langerhans islets in offspring from normal mothers decreased and those in pups from diabetic mothers tended to normalize (P < 0.01), particularly those from the severely sick group (P < 0.01). We conclude that after parturition the offspring is no longer exposed to the high blood sugar levels found in both diabetic groups of mothers, thereby no hyperinsulinemia is needed; as time elapses, then, the area of their Langerhans islets tends to normalization.
Assuntos
Envelhecimento/fisiologia , Animais Recém-Nascidos/anatomia & histologia , Diabetes Mellitus Experimental/fisiopatologia , Ilhotas Pancreáticas/anatomia & histologia , Gravidez em Diabéticas/fisiopatologia , Prenhez/fisiologia , Animais , Feminino , Masculino , Gravidez , Ratos , Ratos Wistar , Valores de ReferênciaRESUMO
The environmental effect on growth and sexual dimorphism is mediated by endocrinological dysfunctions. It was shown that malnutrition acts on the hypotalamus-pituitary-glandular axis. An experiment was made in Wistar rats to determine the effect of some gonadic hormones on the functional components of the skull to which sex dimorphism was alterated by a postnatal undernutrition. The effects of these hormones in restoring sexual cranial dimorphism was tested. Four treatments were applied: control, with food intake ad-libitum; undernutrition (50% of the control food intake); undernutrition plus periodic injections of testosterone and estradiol to males and females, respectively and sham-operated animals, which were injected with oil vehicle only. A radiological longitudinal study was performed between 20 and 80 days of postnatal age. The length width and height of the neural and facial components were measured on each radiograph. Data were processed by ANOVA and Mann-Whitney statistical tests were performed by means of the SYSTAT 7.0 statistical package. Results showed that gonadic hormones restored the sexual cranial dimorphism by stimulating (testosterone) or suppressing (estradiol) the growth of the cranial components.
Assuntos
Estradiol/análogos & derivados , Distúrbios Nutricionais/complicações , Caracteres Sexuais , Testosterona/análogos & derivados , Análise de Variância , Animais , Estradiol/farmacologia , Feminino , Masculino , Radiografia , Ratos , Crânio/anatomia & histologia , Crânio/diagnóstico por imagem , Crânio/efeitos dos fármacos , Estatísticas não Paramétricas , Testosterona/farmacologia , Fatores de TempoRESUMO
In the present work, the effect "in vivo' of increasing doses of RU 38486 upon the hepatic mitochondrial function of diabetic rats has been studied. At the same time, the action of adrenalectomy and corticosterone restitution on this function were comparatively demonstrated. The parameters measured were oxygen consumption with the substrates: 3-hydroxybutyrate (HB), succinate (Suc) and malate-glutamate (Mal-glut) in intact liver mitochondria and the activities of 3-hydroxybutyrate dehydrogenase (HBD) and cytochrome c oxidase (Cyt.c oxid.) enzymes in broken liver mitochondria. The groups of animals studied were normal controls (N) and the following groups of diabetic rats: rats without any treatment (D), adrenalectomized rats (D+ADX), rats that were adrenalectomized and treated with corticosterone (D+ADX+C) and four groups treated with increasing oral doses of RU (in mg/kg body wt.), that is, 12.5 (D+RU1), 25.0 (D+RU2), 37.5 (D+RU3) and 50.0 (D+RU4). The results showed a tendency of increasing values of mitochondrial oxygen consumption in diabetic animals treated with RU. The favourable effect of increasing doses of RU on O2 consumption of diabetic rat liver mitochondria with each of the substrates showed a significant association as indicated by the values obtained for the correlation coefficients r (0.95, 0.97 and 0.99 according to the substrate HB, Succ or Mal-glut, respectively). Likewise, the correlation between the treatment with increasing doses of RU and the recovery of enzyme activities showed a significant dose-effect association with r 0.94 for HBD and r = 0.95 for Cyt.c oxid. Adrenalectomy showed a similar effect to treatment with the maximum dose of RU while corticosterone restitution gave measured values similar to those of the D group. In conclusion, the favourable, significant variation of the hepatic mitochondrial function of diabetic rats was demonstrated by the dose-dependent treatment with RU as seen by the correlation statistical study performed. At the same time, the pernicious effect that glucocorticoids exert upon such function in experimental diabetes was confirmed.
Assuntos
Diabetes Mellitus Experimental/metabolismo , Antagonistas de Hormônios/farmacologia , Mifepristona/farmacologia , Mitocôndrias Hepáticas/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Ácido 3-Hidroxibutírico , Adrenalectomia , Animais , Anti-Inflamatórios/farmacologia , Corticosterona/farmacologia , Diabetes Mellitus Experimental/enzimologia , Relação Dose-Resposta a Droga , Complexo IV da Cadeia de Transporte de Elétrons/efeitos dos fármacos , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Feminino , Hidroxibutirato Desidrogenase/efeitos dos fármacos , Hidroxibutirato Desidrogenase/metabolismo , Hidroxibutiratos/metabolismo , Malatos/metabolismo , Mitocôndrias Hepáticas/enzimologia , Mitocôndrias Hepáticas/metabolismo , Consumo de Oxigênio/fisiologia , Ratos , Succinatos/metabolismo , Ácido SuccínicoRESUMO
Plasma glucose concentrations were measured in: 1) conscious and anesthetized rats during an iv glucose tolerance test (IVGTT) and 2) conscious and anaesthetized phentolamine/propranolol blocked rats during an IVGTT. Anesthesia was induced with ketamine (120 mg.kg-1) or pentobarbitone (60 mg.kg-1) ip at -30 min of the beginning of the IVGTT, which was followed by 2 injections of the anesthetic agents at intervals of 30 min. Propranolol (2 mg.kg-1) was given ip at -25 and -5 min. An iv infusion of phentolamine (0.015 mg.min-1) was started at -20 min and continued up to the end of the experiment. During the IVGTT, the anesthetized rats showed a moderate hyperglycemic response to glucose load compared to conscious animals (ketamine: p < 0.01 at 5 min; and p < 0.05 at 10-20 min; pentobarbitone: p < 0.05 at 5-20 min). The hyperglycemic response to glucose administration in the conscious rats was not affected by adrenergic blockade (p > 0.05). While in ketamine anesthetized rats the increased glucose response was abolished by adrenergic blockade (p < 0.05 at 5-10 min), this effect was not seen in pentobarbitone anesthetized animals. These results suggest the existence of an inhibitory tone on insulin secretion and a glycogenolytic response in ketamine anesthetized rats, probably mediated by adrenergic inervation of the pancreas and liver and by circulating catecholamines secreted from the adrenal medulla.
Assuntos
Glicemia/efeitos dos fármacos , Ketamina/farmacologia , Pentobarbital/farmacologia , Antagonistas Adrenérgicos alfa , Antagonistas Adrenérgicos beta , Análise de Variância , Animais , Glucose/administração & dosagem , Teste de Tolerância a Glucose , Hematócrito , Hiperglicemia/induzido quimicamente , Masculino , Ratos , Ratos WistarRESUMO
Plasma glucose concentrations were measured in: 1) conscious and anesthetized rats during an iv glucose tolerance test (IVGTT) and 2) conscious and anaesthetized phentolamine/propranolol blocked rats during an IVGTT. Anesthesia was induced with ketamine (120 mg.kg-1) or pentobarbitone (60 mg.kg-1) ip at -30 min of the beginning of the IVGTT, which was followed by 2 injections of the anesthetic agents at intervals of 30 min. Propranolol (2 mg.kg-1) was given ip at -25 and -5 min. An iv infusion of phentolamine (0.015 mg.min-1) was started at -20 min and continued up to the end of the experiment. During the IVGTT, the anesthetized rats showed a moderate hyperglycemic response to glucose load compared to conscious animals (ketamine: p < 0.01 at 5 min; and p < 0.05 at 10-20 min; pentobarbitone: p < 0.05 at 5-20 min). The hyperglycemic response to glucose administration in the conscious rats was not affected by adrenergic blockade (p > 0.05). While in ketamine anesthetized rats the increased glucose response was abolished by adrenergic blockade (p < 0.05 at 5-10 min), this effect was not seen in pentobarbitone anesthetized animals. These results suggest the existence of an inhibitory tone on insulin secretion and a glycogenolytic response in ketamine anesthetized rats, probably mediated by adrenergic inervation of the pancreas and liver and by circulating catecholamines secreted from the adrenal medulla.
RESUMO
"In vitro" isometric developed tension (IDT) and frequency of contractions (FC), glucose (Glu), glycogen (GLY) and triglyceride (TG) metabolism, as well as prostaglandin PGE2 and PGE1 production, were studied in uterine strips and in embryos isolated from controls and diabetic rats at day 10 of pregnancy. The IDT and the FC, at 0 time or after a 60 min incubation, were not different in controls and in preparations from diabetic animals when the uterine strips were incubated in glucose or in glucose-free medium (p > 0.05). The production of 14CO2 and 14C-lactate from 14C-glucose were lower in the diabetic group than in controls (p < or = 0.05). Indomethacin (10(-6) M), an inhibitor of prostaglandin synthesis, failed to modify these results. Labelled Glu metabolism by isolated embryos was similar (p > 0.05) in controls and in embryos obtained from diabetic mothers. On the other hand, the initial TG and GLY levels were higher (p < or = 0.05) in diabetic uterine tissues than in controls. However, the values of TG and GLY in embryos obtained from both experimental groups were similar (p > 0.05). TG levels in uterine strips suspended in Glu or in Glu-free medium did not differ (p > 0.05) at 0 time (postisolation) and at 60 min, either in controls or in diabetic rats. However, Gly levels in uterine strips from diabetic animals, decreased significantly at 60 min in tissues incubated in Glu or in Glu-free medium (p < or = 0.05). In controls, uterine Gly content decreased (p < or = 0.05) only at 60 min time when the strips were incubated in Glu-free medium. Finally, uterine tissue from controls as well as from diabetic pregnant rats release more PGE2 than PGE1 into the incubation medium (p < or = 0.001). Nevertheless, secretion of PGE2 and PGE1 was similar in both experimental groups and was not modified by the presence or absence of glucose. In summary, we found differences in uterine metabolism of glucose, glycogen and triglycerides in controls and in diabetic rats, but metabolic differences have not been detected between embryos obtained from controls and from diabetic mothers.