Modulating the electronic structure of amino acids: interaction of model lewis acids with anthranilic acid

On the basis of theoretical B3LYP calculations, Yáñez and co-workers (J. Chem. Theory Comput. 2012, 8, 2293) illustrated that beryllium ions are capable of significantly modulating (changing) the electronic structures of imidazole. In this computational organic chemistry study, the interaction of this β-amino acid and five model Lewis acids (BeF1+, Be2+, AlF2(1+), AlF2+, and Al3+) were investigated. Several aspects were addressed: natural bond orbitals, including second order perturbation analysis of intra-molecular charge delocalization and the natural population analysis atomic charges; molecular geometries; selected infrared stretching frequencies (C-N, C-O, and N-H), and selected ¹H-NMR chemical shifts. The data illustrate that this interaction can weaken the H-O bond and goes beyond strengthening the intra-molecular hydrogen bond (N...H-O) to cause a spontaneous transfer of the proton to the nitrogen atom in five cases generating zwitterion structures. Many new features are observed. Most importantly, the zwitterion structures include a stabilizing hydrogen bond (N-H...O) that varies in relative strength according to the Lewis acid. These findings explain the experimental observations of α-amino acids (for example: J. Am. Chem. Soc. 2001, 123, 3577) and are the first reported fundamental electronic structure characterization of β-amino acids in zwitterion form.

Germinação de sementes e crescimento inicial de plânturas de Pseudopiptadenia psilostachya (DC.) G.P.Lewis & M.P.Lima (Leguminosae) em diferentes anbientes de luz

A expansão da atividade madeireira e a elevada taxa de desmatamento na Amazônia têm intensificado a necessidade de estudos sobre as técnicas mais adequadas para a produção de mudas que possam ser usadas em atividades de reflorestamento e de plantio em florestas. Este estudo teve como objetivo avaliar: a) se a taxa de germinação de sementes de Pseudopiptadenia psilostachya difere entre sementes colhidas na copa e coletadas no chão da floresta; e b) qual o efeito do grau de sombreamento no viveiro sobre a germinação de sementes e o desenvolvimento inicial de plântulas dessa espécie. Seis repetições de 10 sementes colhidas na copa e coletadas no chão foram colocadas em germinador. A taxa de germinação não diferiu entre os dois métodos de obtenção de sementes, sendo recomendada a coleta de frutos no chão. No viveiro, quatro repetições de 25 sementes foram colocadas para germinar a pleno sol e em 30, 50 e 70% de sombra. Em cada tratamento de luz, 40 plântulas foram sorteadas, e sua "performance" foi avaliada quatro meses após a semeadura. Tanto a germinação das sementes quanto o crescimento em diâmetro e acúmulo de biomassa das plântulas foram superiores em 30 e 50% de sombreamento, em comparação com pleno sol. Os resultados indicaram que o crescimento de plântulas de P. psilostachya é favorecido em condições relativamente altas de iluminação, embora algum sombreamento seja necessário, e que a produção de mudas dessa espécie é de fácil execução, ao menos nos estágios iniciais de desenvolvimento das plântulas.

Aplicação do modelo de pulsos retangulares de Bartlett-Lewis modificado para estimativa de eventos extremos de precipitação

Este trabalho teve como objetivo avaliar a modelagem matemática da precipitação pluviométrica horária por meio do modelo de Bartlett-Lewis modificado com seis parâmetros e sua aplicação para estimativa de eventos extremos. Foi utilizada a série de dados pluviográficos do período de outubro de 1980 a dezembro de 2007, da estação meteorológica de Urussanga - SC (latitude 28,31º S, longitude 48,19º W). Foram ajustados os parâmetros mensais do modelo para a precipitação em intervalos de 1 hora, 30 min, 15 min, 10 min e 5 min. Para cada duração estudada, foram simuladas séries com 100 anos de dados. Pode-se concluir que o ajuste dos parâmetros do modelo de Bartlett-Lewis modificado possibilita a simulação de chuvas preservando as propriedades estatísticas da precipitação em vários níveis de agregação temporal. Para as séries de precipitação simulada com duração de 1 hora, observou-se que a série de máximas anuais da série simulada manteve as características da série observada. Também a série de máximas anuais de precipitação diária obtida da agregação da precipitação horária apresentou estatísticas similares às observadas na série histórica. Para durações inferiores, as séries simuladas apresentaram subestimativas superiores a 23%, inviabilizando sua aplicação na estimativa de eventos extremos.

Bartlett-Lewis of rectangular pulse modified model: estimate of parameters for simulation of precipitation in sub-hourly duration

The Bartlett-Lewis Rectangular Pulse Modified (BLPRM) model simulates the precipitous slide in the hourly and sub-hourly and has six parameters for each of the twelve months of the year. This study aimed to evaluate the behavior of precipitation series in the duration of 15 min, obtained by simulation using the model BLPRM in situations: (a) where the parameters are estimated from a combination of statistics, creating five different sets; (b) suitability of the model to generate rain. To adjust the parameters were used rain gauge records of Pelotas/RS/Brazil, which statistics were estimated - mean, variance, covariance, autocorrelation coefficient of lag 1, the proportion of dry days in the period considered. The results showed that the parameters related to the time of onset of precipitation (λ) and intensities (μx) were the most stable and the most unstable were ν parameter, related to rain duration. The BLPRM model adequately represented the mean, variance, and proportion of the dry period of the series of precipitation lasting 15 min and, the time dependence of the heights of rain, represented autocorrelation coefficient of the first retardation was statistically less simulated series suitability for the duration of 15 min.

Efeito do dextran sobre a intensidade das aderências peritoneais intra-abdominais pós-operatórias: estudo experimental em ratos: experimental study in rats

Os autores pesquisam o efeito do Dextran 40 sobre a formação de aderências pós-operatórias em um modelo experimental em ratos. Vinte ratos Wistar foram divididos de forma aleatória em dois grupos. Ambos os grupos foram submetidos a laparotomia mediana e realizada escarificação serosa do peritônio visceral do intestino grosso e peritônio parietal adjacente. O grupo I (controle), formado por dez animais que não receberam tratamento complementar, e o grupo 2, formado por dez animais nos quais administrou-se Dextran 40 na cavidade peritoneal. No vigésimo dia de pós-operatório, os animais foram mortos e submetidos a nova laparotomia mediana e retirada dos segmentos intestinais previamente escarificados. A análise histológica das peças operatórias demonstrou menor formação de fibrose no grupo de animais nos quais foi utilizado Dextran 40 (grupo 2), quando comparados ao grupo controle (p<0,05). Os autores concluem que o Dextran 40 interfere no processo de fibrinogênese reduzindo as aderências intra-abdominais pós-operatórias.

Liver regeneration with l-glutamine supplemented diet: experimental study in rats

OBJECTIVE: To assess liver regeneration in rats after 60% hepatectomy with and without supplementation of L-glutamine through liver weight changes, laboratory parameters and histological study.METHODS: 36 male rats were divided into two groups: glutamine group and control group. Each group was subdivided into three subgroups, with death in 24h, 72h and seven days. The glutamine group received water and standard diet supplemented with L-glutamine, and the control recieved 0.9% saline. In all subgroups analysis of liver regeneration was made by the Kwon formula, study of liver function (AST, ALT, GGT, total bilirubin, indirect and indirect bilirubin and albumin) and analysis of cell mitosis by hematoxylin-eosin.RESULTS: In both groups there was liver regeneration by weight gain. Gamma-GT increased significantly in the control group (p < 0.05); albumin increased in the glutamine group. The other indicators of liver function showed no significant differences. Histological analysis at 72h showed a higher number of mitoses in the glutamine group, with no differences in other subgroups.CONCLUSION: Diet supplementation with L glutamine is beneficial for liver regeneration.

Effects of splenic allograft in lipid profile of non-splenectomized rats: the immune and metabolic role of the "double spleen"

OBJECTIVE: To elucidate the role of the spleen and splenic allograft in lipid control and evaluate its effect on the lipid profile of rats.METHOD: 32 male Wistar rats were randomly assigned into four groups: control group (1), total splenectomy group (2), splenectomy and implantation of allograft group (3) and double spleen group (4). Each group was subdivided into two subgroups: A and B, based on the death of the animals after 30 or 120 days of monitoring. The procedures in groups 2, 3 and 4 were made simultaneously, and splenectomized animals, groups 2 and 3 were donors, respectively, for the animals of groups 3 and 4. In group 4 the spleen was preserved and the animals received implants from the spleens of rats from group 3. The regeneration of splenic tissue was evaluated by macroscopic and microscopic analyzes of the grafts and own spleens, as well as with measurements of VLDL, HDL, LDL, total cholesterol and triglycerides.RESULTS: after 120 days, Group 4 showed levels of total cholesterol and LDL lower than the other groups. Group 1 had higher levels of lipids.CONCLUSION: The technique of double spleen was effective in the control of lipid metabolism, corroborating the function of the spleen as a reserve of lipids.

Standardization of pulmonary ventilation technique using volume-controlled ventilators in rats with congenital diaphragmatic hernia

OBJECTIVE: To standardize a technique for ventilating rat fetuses with Congenital Diaphragmatic Hernia (CDH) using a volume-controlled ventilator.METHODS: Pregnant rats were divided into the following groups: a) control (C); b) exposed to nitrofen with CDH (CDH); and c) exposed to nitrofen without CDH (N-). Fetuses of the three groups were randomly divided into the subgroups ventilated (V) and non-ventilated (N-V). Fetuses were collected on day 21.5 of gestation, weighed and ventilated for 30 minutes using a volume-controlled ventilator. Then the lungs were collected for histological study. We evaluated: body weight (BW), total lung weight (TLW), left lung weight (LLW), ratios TLW / BW and LLW / BW, morphological histology of the airways and causes of failures of ventilation.RESULTS: BW, TLW, LLW, TLW / BW and LLW / BW were higher in C compared with N- (p <0.05) and CDH (p <0.05), but no differences were found between the subgroups V and N-V (p> 0.05). The morphology of the pulmonary airways showed hypoplasia in groups N- and CDH, with no difference between V and N-V (p <0.05). The C and N- groups could be successfully ventilated using a tidal volume of 75 ìl, but the failure of ventilation in the CDH group decreased only when ventilated with 50 ìl.CONCLUSION: Volume ventilation is possible in rats with CDH for a short period and does not alter fetal or lung morphology.

Effect of the celexoxib in microscopic changes of the esophageal mucosal of rats induced by esofagojejunostomy

OBJECTIVE: To evaluate the protective effect of celecoxib in the esophageal mucosa in rats undergoing esofagojejunostomy.METHODS: Sixty male Wistar rats from the vivarium of the University of Health Sciences of Alagoas were used for the experiment. The animals were divided into four groups: Group I, 15 rats undergoing esofagojejunostomy with the use of celecoxib postoperatively; Group II, 15 rats undergoing esofagojejunostomy without the use of celecoxib; Group III, 15 rats undergoing celiotomy with bowel manipulation; and Group IV, 15 rats without surgery and using celecoxib. The observation period was 90 days. After the death of the animals, the distal segment of the esophagus was resected and sent for microscopic analysis.RESULTS: esofagojejunostomy caused macroscopic and microscopic esophagitis. Esophagitis was equal in both groups I and II. In groups III and IV esophageal lesions were not developed.CONCLUSIONS: celecoxib had neither protective nor inducing effect on esophagitis, but had a protective effect on dysplasia of the animals of group I.

Comparison between electrocautery and fibrin selant after hepatectomy in rats

OBJECTIVE: To compare between electrocautery and fibrin sealant hemostasis in rats after partial hepatectomy.METHODS: we used 24 Wistar rats, which were submitted to 30% hepatic resection, divided into two groups of 12 animals each: Group Electrocautery and Group Tachosil(r). These animals were evaluated after three and 14 days. We assessed the presence of complications, laboratory tests and histological exam of the recovered liver.RESULTS: the presence of abscess was more prevalent in the electrocautery group. The observed adhesions were more pronounced in the electrocautery group, both in frequency and in intensity, after three and 14 days. There were no deaths in either group. As for laboratory analysis, after three days the hematocrit was lower in the TachoSil(r) Group. The elevation of AST and ALT were more pronounced in the electrocautery group (p = 0.002 and p = 0.004) in three days. Histological analysis of specimens collected on the third day after surgery showed similar results in both groups for the presence of polymorphonuclear cells, whereas mononuclear was more evident in the TachoSil(r) group. We also observed that angiogenesis, although present in both groups, was more pronounced in the TachoSil(r) group (p = 0.030). However, on the 14th day angiogenesis was more pronounced in the electrocautery group, but without statistical significance.CONCLUSION: hemostasis achieved by the groups was similar; however, the use of electrocautery was associated with infections, adhesions at higher grades and elevated liver enzymes.

Sirolimus influence on hepatectomy-induced liver regeneration in rats

OBJECTIVE: To evaluate the influence of sirolimus on liver regeneration triggered by resection of 70% of the liver of adult rats.METHODS: we used 40 Wistar rats randomly divided into two groups (study and control), each group was divided into two equal subgroups according to the day of death (24 hours and seven days). Sirolimus was administered at a dose of 1mg/kg in the study group and the control group was given 1 ml of saline. The solutions were administered daily since three days before hepatectomy till the rats death to removal of the regenerated liver, conducted in 24 hours or 7 days after hepatectomy. Liver regeneration was measured by the KWON formula, by thenumber of mitotic figures (hematoxylin-eosin staining) and by the immunohistochemical markers PCNA and Ki-67.RESULTS: there was a statistically significant difference between the 24h and the 7d groups. When comparing the study and control groups in the same period, there was a statistically significant variation only for Ki-67, in which there were increased numbers of hepatocytes in cell multiplication in the 7d study group compared with the 7d control group (p = 0.04).CONCLUSION: there was no negative influence of sirolimus in liver regeneration and there was a positive partial effect at immunohistochemistry with Ki-67.

Natural history of extensive diaphragmatic injury on the right side: experimental study in rats

OBJECTIVE: To evaluate the natural healing of the rat diaphragm that suffered an extensive right penetrating injury.METHODS: Animals were submitted to an extensive penetrating injury in right diaphragm. The sample consisted of 40 animals. The variables studied were initial weight, weight 21 days after surgery; healing of the diaphragm, non-healing of the diaphragm, and herniated abdominal contents into the chest.RESULTS: Ten animals were used as controls for weight and 30 animals were operated. Two animals died during the experiment, so 28 animals formed the operated group; healing of the diaphragm occurred in 15 animals (54%), 11 other animals showed diaphragmatic hernia (39%) and in two we observed only diaphragmatic injury without hernia (7%). Among the herniated organs, the liver was found in 100% of animals, followed by the omentum in 77%, small bowel in 62%, colon in 46%, stomach in 31% and spleen in 15%. The control group and the diaphragmatic healing subgroup showed increased weight since the beginning of the study and the 21 days after surgery (p <0.001). The unhealed group showed no change in weight (p = 0.228).CONCLUSION: there is a predominance of spontaneous healing in the right diaphragm; animals in which there was no healing of the diaphragm did not gain weight, and the liver was the organ present in 100% the diaphragmatic surface in all rats with healed diaphragm or not.

Scintigraphic study of the splenic circulation in rats

Objective: To evaluate the splenic parenchymal blood distribution through scintigraphic study.Methods: Thirty Wistar rats were randomly divided into six groups (n = 5). Group 1 (spleen - 30 minutes) and Group 2 (spleen - 90 minutes) underwent laparotomy with direction of blood flow to the spleen by ligature of the aorta near the iliac bifurcation and splanchnic vessels, keeping blood flow only in the splenic artery; Group 3 (spleen and stomach - 30 minutes) and Group 4 (spleen and stomach - 90 minutes) underwent laparotomy with direction of blood flow to the spleen and stomach by ligature of the aorta near the iliac bifurcation and splanchnic vessels, maintaining the flow through the splenic, gastric and splenogastric vessels; Group 5 (control - 30 minutes) and Group 6 (control - 90 minutes) underwent laparotomy and ligation of the aorta near the iliac bifurcation, keeping the flow to the abdominal organs. After arterial ligation, the animals received an injection of 0.2 ml of sodium pertechnetate in the aorta. Scintigraphic images were taken and the animals had their spleens removed for radioactivity counting with an automatic counter device.Results: There was no difference in the amounts of radiation from the spleen between groups, indicating retention of the radioisotope by the spleen, even after the period of 90 minutes.Conclusion: The blood flow through the spleen is not continuous. The blood diffuses through the splenic parenchyma and its venous drainage is slow, not following a predictable sequence.

The effects of supraphysiological supplementation of b-carotene in spontaneously hypertensive rats (SHR and SHR-sp)

Objective: to investigate the effect of administration of supraphysiological âcaroteno on biological parameters (ectoscopy and blood pressure), laboratory (malondialdehyde) and histological (liver and carotid arteries) of spontaneously hypertensive rats prone to stroke (SHR-sp).Methods: we used 36 male rats were divided into three groups, each containing 12 rats Wistar, SHR and SHR-sp, subdivided into six control animals and six animals treated with supraphysiological doses of âcaroteno for two periods of ten weeks interspersed with one week interruption. In the experiment were assessed daily physical examination and blood pressure (plethysmography). At sacrifice, blood was collected for measurement of serum malondialdehyde, liver and carotid arteries for histological examination.Results: temporary change in color of the fur, decreased significantly (p<0.0001) blood pressure (20mg supplementation âcaroteno) and serum levels of malondialdehyde (p<0.05) and increased amount of elastic fibers in the carotid wall of SHR and SHR-sp.Conclusion: supplementation of supraphysiological âcaroteno caused no toxic effects, showed positive response in the modulation of blood pressure and lower serum malondialdehyde. No significant morphological changes were found in both groups, except an increase in the number of elastic fibers in the muscle layer carotid suggesting elastosis in SHR and SHR-sp.

Use of the amniotic membrane to cover the peritoneal cavity in the reconstruction of the abdominal wall with polypropylene mesh in rats

OBJECTIVE: to evaluate the efficacy of the amniotic membrane used with polypropylene mesh against the formation of adhesions and its influence on healing. METHODS: twenty five female Wistar rats were anesthetized for creating a parietal defect in the anterior abdominal wall. Its correction was made with polypropylene mesh alone and associated with amniotic membrane. In the control group (n=11), the screen was inserted alone. In group A (n=7) we interposed the amniotic membrane between the screen and the abdominal wall. In group B, the amniotic membrane was placed on the mesh, covering it. After seven days, the animals were euthanized for macroscopic and microscopic evaluation of healing. RESULTS: adhesions were observed in all animals except one in the control group. Severe inflammation was observed in all animals in groups A and B and in three of the control group, with significant difference between them (A and B with p=0.01). Pronounced angiogenic activity was noted in one animal in the control group, six in group A and four in group B, with a significant difference between the control group and group A (p=0.002) and group B (p=0.05). The scar collagen was predominantly mature, except in five animals of the control group, with significant difference between the control group and group A (p=0.05) and group B (p=0.05). CONCLUSION: The amniotic membrane did not alter the formation of adhesions in the first postoperative week. There were also pronounced inflammation, high angiogenic activity and predominance of mature collagen fibers, regardless of the anatomical plane that it was inserted in.