Aim: To evaluate the prevalence of orofacial injuries during practice of sports and the use of mo... more Aim: To evaluate the prevalence of orofacial injuries during practice of sports and the use of mouthguards by university students in the southern region of Brazil. Methods: In this crosssectional study, 700 undergraduates from the University of West Santa Catarina, Brazil, filled out a questionnaire with multiple-choice questions addressing social and economic status, education level of parents, orofacial injuries from sport practice, knowledge, importance and use of mouthguards. The collected data were entered into the EpiData 3.2 program, and were analyzed by descriptive statistics and the chi-square test using STATA 8.0 statistical software package with a significance level set at 5%. Results: Out of the total number of students surveyed, 37.02% claimed to have already sustained some kind of orofacial injury. Out of these, only 9.90% sought dental assistance after trauma. The most common injuries were: bleeding 54.55%, swelling 23.72%, and dental fractures 16.21%. Among the inter...
El Plan de Gestión Ambiental Empresarial (PGA-E), es una herramienta que permite mejorar, de form... more El Plan de Gestión Ambiental Empresarial (PGA-E), es una herramienta que permite mejorar, de forma organizada, el desempeño ambiental de la CNFL; ya que orienta y prioriza la atención de todos los aspectos ambientales significativos, que se han identificado en las diferentes actividades y procesos productivos de la empresa. El PGAE se encuentra alineado con el objetivo estratégico de la CNFL: “Consolidar la sostenibilidad ambiental de la empresa con perspectiva de excelencia en los servicios y responsabilidad social”. El PGAE se encuentra alineado con la Política Ambiental de la CNFL y permite cumplir con las disposiciones del Decreto No36499S-MINAET “Reglamento para la elaboración de programas de gestión ambiental institucional en el sector público de Costa Rica”. El PGAE está compuesto por los programas ambientales que se describen a continuación:
BACKGROUND & AIMS-Most cholestatic disorders are caused by defects in cholangiocytes. The type 3 ... more BACKGROUND & AIMS-Most cholestatic disorders are caused by defects in cholangiocytes. The type 3 isoform of the inositol 1,4,5-trisphosphate receptor (ITPR3) is the intracellular calcium release channel detected most frequently in cholangiocytes. ITPR3 is required for bicarbonate secretion by bile ducts, and its expression is reduced in intrahepatic bile ducts of patients with cholestatic disorders. We investigated whether the nuclear factor, erythroid 2-like 2 (NFE2L2 or NRF2), which is sensitive to oxidative stress, regulates expression of ITPR3. METHODS-The activity of the ITPR3 promoter was measured in normal human cholangiocyte (NHC) cells and primary mouse cholangiocytes. Levels of ITPR3 protein and mRNA were examined by immunoblot and PCR analyses, respectively. ITPR3 activity was determined by measuring calcium signaling in normal human cholangiocyte cells and secretion in isolated bile duct units. Levels of NRF2 were measured in liver tissues from rats with cholestasis (induced by administration of alpha-napthylisothiocyanate) and from patients with biliary diseases.
Anales de pediatría (Barcelona, Spain : 2003), 2005
In the past two decades, type 2 diabetes mellitus has increased in children and adolescents, espe... more In the past two decades, type 2 diabetes mellitus has increased in children and adolescents, especially within certain ethnic groups. This increase has been parallel to the rising prevalence of obesity. Because of the overlap between some clinical characteristics, the differential diagnosis between type 1 and 2 diabetes is difficult. Of 300 diabetic patients in our diabetes section, only three (1 %) had type 2 diabetes. Two patients were obese adolescents with a positive family history of type 2 diabetes mellitus; the third patient was a prepubertal, overweight girl with no family history of this disorder. The diagnosis was incidental in two patients and one patient presented with ketoacidosis. The differences between the three patients reveal the great clinical variability of this disorder and suggest that various underlying factors are involved in the pathophysiology of type 2 diabetes.
The Birkhoff transformation for the restricted circular planar three body problem is introduced u... more The Birkhoff transformation for the restricted circular planar three body problem is introduced using a Hamiltonian formalism. A generalization of the Birkhoff transformation (hereafter the B 3 transformation) is derived in order to regularize the circular spatial three body problem by means of a geometrical approach. These transformations have the important property to provide a simoultaneous regularization of two singularities.
Extended synaptotagmins (E-Syts) are a recently identified family of proteins that tether the end... more Extended synaptotagmins (E-Syts) are a recently identified family of proteins that tether the endoplasmic reticulum (ER) to the plasma membrane (PM) in part by conferring regulation of cytosolic calcium (Ca2+) at these contact sites (Cell, 2013). However, the mechanism by which E-Syts link this tethering to Ca2+ signaling is unknown. Ca2+ waves in polarized epithelia are initiated by inositol 1,4,5-trisphosphate receptors (InsP3Rs), and these waves begin in the apical region because InsP3Rs are targeted to the ER adjacent to the apical membrane. In this study we investigated whether E-Syts are responsible for this targeting. Primary rat hepatocytes were used as a model system, because a single InsP3R isoform (InsP3R-II) is tethered to the peri-apical ER in these cells. Additionally, it has been established in hepatocytes that the apical localization of InsP3Rs is responsible for Ca2+ waves and secretion and is disrupted in disease states in which secretion is impaired. We found that...
Este artigo apresenta resultados de uma investigação que buscou compreender a relação com o saber... more Este artigo apresenta resultados de uma investigação que buscou compreender a relação com o saber de estudantes universitários, utilizando como referencial a teoria da relação com o saber de Bernard Charlot. O campo de pesquisa foi uma universidade comunitária localizada em um município de porte médio do estado de Minas Gerais, sendo que os sujeitos da pesquisa foram 400 estudantes de 24 cursos de graduação. A coleta de dados foi realizada por meio dos balanços de saber, instrumento proposto por Bernard Charlot, que consiste na demanda da produção de um texto a respeito das aprendizagens do sujeito. Após a apresentação dos aspectos quantitativos da classificação das aprendizagens evocadas pelos estudantes, o artigo discute a preponderância das aprendizagens ligadas ao desenvolvimento pessoal e utiliza as categorias mobilização e sentido para aprofundar a compreensão dos relatos produzidos pelos estudantes nos balanços de saber. Conclui que a relação com o saber dos sujeitos da pesqu...
Intracellular free Ca 2+ ([Ca 2+ ]i) is a highly versatile second messenger that regulates a wide... more Intracellular free Ca 2+ ([Ca 2+ ]i) is a highly versatile second messenger that regulates a wide range of functions in every type of cell and tissue. To achieve this versatility, the Ca 2+ signaling system operates in a variety of ways to regulate cellular processes that function over a wide dynamic range. This is particularly well exemplified for Ca 2+ signals in the liver, which modulate diverse and specialized functions such as bile secretion, glucose metabolism, cell proliferation, and apoptosis. These Ca 2+ signals are organized to control distinct cellular processes through tight spatial and temporal coordination of [Ca 2+ ]i signals, both within and between cells. This article will review the machinery responsible for the formation of Ca 2+ signals in the liver, the types of subcellular, cellular, and intercellular signals that occur, the physiological role of Ca 2+ signaling in the liver, and the role of Ca 2+ signaling in liver disease.
Trypanosoma brucei is the cause of the diseases known as sleeping sickness in humans (T. brucei s... more Trypanosoma brucei is the cause of the diseases known as sleeping sickness in humans (T. brucei ssp. gambiense and ssp. rhodesiense) and ngana in domestic animals (T. brucei brucei) in Africa. Procyclic trypomastigotes, the tsetse vector stage, express a surface-bound trans-sialidase that transfers sialic acid to the glycosylphosphatidylinositol anchor of procyclin, a surface glycoprotein covering the parasite surface. Trans-sialidase is a unique enzyme expressed by a few trypanosomatids that allows them to scavenge sialic acid from sialylated compounds present in the infected host. The only enzyme extensively characterized is that of the American trypanosome T. cruzi (TcTS). In this work we identified and characterized the gene encoding the trans-sialidase from T. brucei brucei (TbTS). TbTS genes are present at a small copy number, at variance with American trypanosomes where a large gene family is present. The recombinant TbTS protein has both sialidase and trans-sialidase activity, but it is about 10 times more efficient in transferring than in hydrolysing sialic acid. Its N-terminus contains a region of 372 amino acids that is 45% identical to the catalytic domain of TcTS and contains the relevant residues required for catalysis. The enzymatic activity of mutants at key positions involved in the transfer reaction revealed that the catalytic sites of TcTS and TbTS are likely to be similar, but are not identical. As in the case of TcTS and TrSA, the substitution of a conserved tryptophanyl residue changed the substrate specificity rendering a mutant protein capable of hydrolysing both alpha-(2,3) and alpha-(2,6)-linked sialoconjugates.
Food-restricted animals present metabolic adaptations that facilitate food-seeking behavior and d... more Food-restricted animals present metabolic adaptations that facilitate food-seeking behavior and decelerate energy utilization by reducing the hypothalamus-pituitary-thyroid (HPT) axis function. Stress by dehydration induces an anorexic behavior in rats, loss of weight and reduced food intake when compared to ad libitum fed animals, however these alterations are accompanied by HPT axis changes such as increased serum thyrotropin levels and enhanced expression of thyrotropin-releasing hormone (TRH) in the paraventricular nucleus of the hypothalamus, which is considered as anorexigenic peptide. In contrast, a pair-fed group conformed by forced-food-restricted animals (FFR) (eating the exact same amount of food as dehydration-induced anorexic rats-DIA rats) present decreased TRH mRNA levels. NPY synthesis in the arcuate nucleus and orexin-expressing neurons from the lateral hypothalamic area (LHA) are activated during food restriction. These brain structures project into PVN, suggesting that NPY and orexins are possible factors involved in TRHergic neuron activation in DIA rats. Leptin signaling is another likely factor to be involved in TRH differential expression. Therefore, to gain more insight into the regulation of the feeding behavior in the experimental models, we analyzed Y1, Y5, Ox1-R and Ob-R b mRNA levels in PVN and preproorexin in LHA, since their signaling to the PVN might be altering TRH synthesis and feeding in DIA animals. Prepro-orexinergic cells were activated in FFR animals; Ox1-R and Y1 expression was reduced in FFR vs. controls or DIA group. Compensatory changes in PVN receptor expression of some feeding-related peptides in anorexic rats may alter TRHergic neural response to energy demands.
Wistar rats subjected to dehydration-induced anorexia (DIA), with 2.5% NaCl solution as drinking ... more Wistar rats subjected to dehydration-induced anorexia (DIA), with 2.5% NaCl solution as drinking water for 7 days, decrease by 80% their food intake and present some changes common to pair-fed food restricted rats (FFR) such as: weight loss, decreased serum leptin and expression of orexigenic arcuate peptides, increasing the anorexigenic ones and serum corticosterone levels. In contrast, the response of the HPT axis differs: DIA animals have increased TRH expression in PVN and present primary as opposed to the tertiary hypothyroidism of the FFR. Exclusive to DIA is the activation of CRHergic neurons in the lateral hypothalamus (LH) that project to PVN. Since TRH neurons of the PVN contain CRH receptors, we hypothesized that the differences in the response of the HPT axis to DIA could be due to CRH regulating TRHergic neurons. CRH effect was first evaluated on TRH expression of cultured hypothalamic cells where TRH mRNA levels increased after 1h with 0.1nM of CRH. We then measured the mRNA levels of CRH receptors in the PVN of male and female rats subjected to DIA; only those of CRH-R2 were modulated (down-regulated). The CRH-R2 antagonist antisauvagine-30 was therefore injected into the PVN of male rats, during the 7 days of DIA. Antisauvagine-30 induced a higher food intake than controls, and impeded the changes produced by DIA on the HPT axis: PVN TRH mRNA, and serum TH and TSH levels were decreased to similar values of FFR animals. Results corroborate the anorexigenic effect of CRH and show its role, acting through CRH-R2 receptors, in the activation of TRHergic PVN neurons caused by DIA. These new data further supports clinical trials with CRH-R2 antagonists in anorexia nervosa patients.
Alcohol drinking and tobacco smoking are assumed to have significant independent and joint effect... more Alcohol drinking and tobacco smoking are assumed to have significant independent and joint effects on oral cancer (OC) development. This assumption is based on consistent reports from observational studies, which, however, overestimated the independent effects of smoking and drinking, because they did not account for the interaction effect in multivariable analyses. This case-control study sought to investigate the independent and the joint effects of smoking and drinking on OC in a homogeneous sample of adults. Case patients (N = 1,144) were affected by invasive oral/oropharyngeal squamous cell carcinoma confirmed histologically, diagnosed between 1998 and 2008 in four hospitals of São Paulo (Brazil). Control patients (N = 1,661) were not affected by drinking-, smoking-associated diseases, cancers, upper aero-digestive tract diseases. Cumulative tobacco and alcohol consumptions were assessed anamnestically. Patients were categorized into never/ever users and never/level-1/level-2 users, according to the median consumption level in controls. The effects of smoking and drinking on OC adjusted for age, gender, schooling level were assessed using logistic regression analysis; Model-1 did not account for the smoking-drinking interaction; Model-2 accounted for this interaction and included the resultant interaction terms. The models were compared using the likelihood ratio test. According to Model-1, the adjusted odds ratios (ORs) for smoking, drinking, smoking-drinking were 3.50 (95% confidence interval-95CI, 2.76-4.44), 3.60 (95CI, 2.86-4.53), 12.60 (95CI, 7.89-20.13), respectively. According to Model-2 these figures were 1.41 (95CI, 1.02-1.96), 0.78 (95CI, 0.48-1.27), 8.16 (95CI, 2.09-31.78). Analogous results were obtained using three levels of exposure to smoking and drinking. Model-2 showed statistically significant better goodness-of-fit statistics than Model-1. Drinking was not independently associated with OC, while the independent effect of smoking was lower than expected, suggesting that observational studies should be revised adequately accounting for the smoking-drinking interaction. OC control policies should focus on addictive behaviours rather than on single lifestyle risk factors.
The MBT repeat has been recently identified as a key domain capable of methyl-lysine histone reco... more The MBT repeat has been recently identified as a key domain capable of methyl-lysine histone recognition. Functional work has pointed to a role for MBT domain-containing proteins in transcriptional repression of developmental control genes such as Hox genes. In this study, L3MBTL2, a human homolog of Drosophila Sfmbt critical for Hox gene silencing, is demonstrated to preferentially recognize lower methylation states of several histone-derived peptides through its fourth MBT repeat. High-resolution crystallographic analysis of the four MBT repeats of this protein reveals its unique asymmetric rhomboid architecture, as well as binding mechanism, which preclude the interaction of the first three MBT repeats with methylated peptides. Structural elucidation of an L3MBTL2-H4K20me1 complex and comparison with other MBT-histone peptide complexes also suggests that an absence of distinct surface contours surrounding the methyl-lysine-binding pocket may underlie the lack of sequence specificity observed for members of this protein family.
Background: The insular cortex (IC) receives somatosensory afferent input and has been related to... more Background: The insular cortex (IC) receives somatosensory afferent input and has been related to nociceptive input. It has dopaminergic terminals and D1 (D1R) -excitatory- and D2 (D2R) -inhibitory- receptors. D2R activation with a selective agonist, as well as D1R blockade with antagonists in the IC, diminish neuropathic nociception in a nerve transection model. An intraplantar injection of carrageenan and acute thermonociception (plantar test) were performed to measure the response to inflammation (paw withdrawal latency, PWL). Simultaneously, a freely moving microdyalisis technique and HPLC were used to measure the release of dopamine and its metabolites in the IC. Plantar test was applied prior, one and three hours after inflammation. Also, mRNA levels of D1 and D2R's were measured in the IC after three hours of inflammation. Results: The results showed a gradual decrease in the release of dopamine, Dopac and HVA after inflammation. The decrease correlates with a decrease in...
Modified sialic acid substrates have been used to label Trypanosoma cruzi trans-sialidase, demons... more Modified sialic acid substrates have been used to label Trypanosoma cruzi trans-sialidase, demonstrating that the enzyme catalyses the transfer of sialic acid through a covalent glycosyl-enzyme intermediate, a mechanism common to most retaining glycosidases. Peptic digestion of labeled protein, followed by LC-MS/MS analysis of the digest, identified Tyr342 as the catalytic nucleophile. This is the first such example of a retaining glycosidase utilizing an aryl glycoside intermediate. It is suggested that this alternative choice of nucleophile is a consequence of the chemical nature of sialic acid. A Tyr/Glu couple is invoked to relay charge from a remote glutamic acid, thereby avoiding electrostatic repulsion with the sialic acid carboxylate group.
Aim: To evaluate the prevalence of orofacial injuries during practice of sports and the use of mo... more Aim: To evaluate the prevalence of orofacial injuries during practice of sports and the use of mouthguards by university students in the southern region of Brazil. Methods: In this crosssectional study, 700 undergraduates from the University of West Santa Catarina, Brazil, filled out a questionnaire with multiple-choice questions addressing social and economic status, education level of parents, orofacial injuries from sport practice, knowledge, importance and use of mouthguards. The collected data were entered into the EpiData 3.2 program, and were analyzed by descriptive statistics and the chi-square test using STATA 8.0 statistical software package with a significance level set at 5%. Results: Out of the total number of students surveyed, 37.02% claimed to have already sustained some kind of orofacial injury. Out of these, only 9.90% sought dental assistance after trauma. The most common injuries were: bleeding 54.55%, swelling 23.72%, and dental fractures 16.21%. Among the inter...
El Plan de Gestión Ambiental Empresarial (PGA-E), es una herramienta que permite mejorar, de form... more El Plan de Gestión Ambiental Empresarial (PGA-E), es una herramienta que permite mejorar, de forma organizada, el desempeño ambiental de la CNFL; ya que orienta y prioriza la atención de todos los aspectos ambientales significativos, que se han identificado en las diferentes actividades y procesos productivos de la empresa. El PGAE se encuentra alineado con el objetivo estratégico de la CNFL: “Consolidar la sostenibilidad ambiental de la empresa con perspectiva de excelencia en los servicios y responsabilidad social”. El PGAE se encuentra alineado con la Política Ambiental de la CNFL y permite cumplir con las disposiciones del Decreto No36499S-MINAET “Reglamento para la elaboración de programas de gestión ambiental institucional en el sector público de Costa Rica”. El PGAE está compuesto por los programas ambientales que se describen a continuación:
BACKGROUND & AIMS-Most cholestatic disorders are caused by defects in cholangiocytes. The type 3 ... more BACKGROUND & AIMS-Most cholestatic disorders are caused by defects in cholangiocytes. The type 3 isoform of the inositol 1,4,5-trisphosphate receptor (ITPR3) is the intracellular calcium release channel detected most frequently in cholangiocytes. ITPR3 is required for bicarbonate secretion by bile ducts, and its expression is reduced in intrahepatic bile ducts of patients with cholestatic disorders. We investigated whether the nuclear factor, erythroid 2-like 2 (NFE2L2 or NRF2), which is sensitive to oxidative stress, regulates expression of ITPR3. METHODS-The activity of the ITPR3 promoter was measured in normal human cholangiocyte (NHC) cells and primary mouse cholangiocytes. Levels of ITPR3 protein and mRNA were examined by immunoblot and PCR analyses, respectively. ITPR3 activity was determined by measuring calcium signaling in normal human cholangiocyte cells and secretion in isolated bile duct units. Levels of NRF2 were measured in liver tissues from rats with cholestasis (induced by administration of alpha-napthylisothiocyanate) and from patients with biliary diseases.
Anales de pediatría (Barcelona, Spain : 2003), 2005
In the past two decades, type 2 diabetes mellitus has increased in children and adolescents, espe... more In the past two decades, type 2 diabetes mellitus has increased in children and adolescents, especially within certain ethnic groups. This increase has been parallel to the rising prevalence of obesity. Because of the overlap between some clinical characteristics, the differential diagnosis between type 1 and 2 diabetes is difficult. Of 300 diabetic patients in our diabetes section, only three (1 %) had type 2 diabetes. Two patients were obese adolescents with a positive family history of type 2 diabetes mellitus; the third patient was a prepubertal, overweight girl with no family history of this disorder. The diagnosis was incidental in two patients and one patient presented with ketoacidosis. The differences between the three patients reveal the great clinical variability of this disorder and suggest that various underlying factors are involved in the pathophysiology of type 2 diabetes.
The Birkhoff transformation for the restricted circular planar three body problem is introduced u... more The Birkhoff transformation for the restricted circular planar three body problem is introduced using a Hamiltonian formalism. A generalization of the Birkhoff transformation (hereafter the B 3 transformation) is derived in order to regularize the circular spatial three body problem by means of a geometrical approach. These transformations have the important property to provide a simoultaneous regularization of two singularities.
Extended synaptotagmins (E-Syts) are a recently identified family of proteins that tether the end... more Extended synaptotagmins (E-Syts) are a recently identified family of proteins that tether the endoplasmic reticulum (ER) to the plasma membrane (PM) in part by conferring regulation of cytosolic calcium (Ca2+) at these contact sites (Cell, 2013). However, the mechanism by which E-Syts link this tethering to Ca2+ signaling is unknown. Ca2+ waves in polarized epithelia are initiated by inositol 1,4,5-trisphosphate receptors (InsP3Rs), and these waves begin in the apical region because InsP3Rs are targeted to the ER adjacent to the apical membrane. In this study we investigated whether E-Syts are responsible for this targeting. Primary rat hepatocytes were used as a model system, because a single InsP3R isoform (InsP3R-II) is tethered to the peri-apical ER in these cells. Additionally, it has been established in hepatocytes that the apical localization of InsP3Rs is responsible for Ca2+ waves and secretion and is disrupted in disease states in which secretion is impaired. We found that...
Este artigo apresenta resultados de uma investigação que buscou compreender a relação com o saber... more Este artigo apresenta resultados de uma investigação que buscou compreender a relação com o saber de estudantes universitários, utilizando como referencial a teoria da relação com o saber de Bernard Charlot. O campo de pesquisa foi uma universidade comunitária localizada em um município de porte médio do estado de Minas Gerais, sendo que os sujeitos da pesquisa foram 400 estudantes de 24 cursos de graduação. A coleta de dados foi realizada por meio dos balanços de saber, instrumento proposto por Bernard Charlot, que consiste na demanda da produção de um texto a respeito das aprendizagens do sujeito. Após a apresentação dos aspectos quantitativos da classificação das aprendizagens evocadas pelos estudantes, o artigo discute a preponderância das aprendizagens ligadas ao desenvolvimento pessoal e utiliza as categorias mobilização e sentido para aprofundar a compreensão dos relatos produzidos pelos estudantes nos balanços de saber. Conclui que a relação com o saber dos sujeitos da pesqu...
Intracellular free Ca 2+ ([Ca 2+ ]i) is a highly versatile second messenger that regulates a wide... more Intracellular free Ca 2+ ([Ca 2+ ]i) is a highly versatile second messenger that regulates a wide range of functions in every type of cell and tissue. To achieve this versatility, the Ca 2+ signaling system operates in a variety of ways to regulate cellular processes that function over a wide dynamic range. This is particularly well exemplified for Ca 2+ signals in the liver, which modulate diverse and specialized functions such as bile secretion, glucose metabolism, cell proliferation, and apoptosis. These Ca 2+ signals are organized to control distinct cellular processes through tight spatial and temporal coordination of [Ca 2+ ]i signals, both within and between cells. This article will review the machinery responsible for the formation of Ca 2+ signals in the liver, the types of subcellular, cellular, and intercellular signals that occur, the physiological role of Ca 2+ signaling in the liver, and the role of Ca 2+ signaling in liver disease.
Trypanosoma brucei is the cause of the diseases known as sleeping sickness in humans (T. brucei s... more Trypanosoma brucei is the cause of the diseases known as sleeping sickness in humans (T. brucei ssp. gambiense and ssp. rhodesiense) and ngana in domestic animals (T. brucei brucei) in Africa. Procyclic trypomastigotes, the tsetse vector stage, express a surface-bound trans-sialidase that transfers sialic acid to the glycosylphosphatidylinositol anchor of procyclin, a surface glycoprotein covering the parasite surface. Trans-sialidase is a unique enzyme expressed by a few trypanosomatids that allows them to scavenge sialic acid from sialylated compounds present in the infected host. The only enzyme extensively characterized is that of the American trypanosome T. cruzi (TcTS). In this work we identified and characterized the gene encoding the trans-sialidase from T. brucei brucei (TbTS). TbTS genes are present at a small copy number, at variance with American trypanosomes where a large gene family is present. The recombinant TbTS protein has both sialidase and trans-sialidase activity, but it is about 10 times more efficient in transferring than in hydrolysing sialic acid. Its N-terminus contains a region of 372 amino acids that is 45% identical to the catalytic domain of TcTS and contains the relevant residues required for catalysis. The enzymatic activity of mutants at key positions involved in the transfer reaction revealed that the catalytic sites of TcTS and TbTS are likely to be similar, but are not identical. As in the case of TcTS and TrSA, the substitution of a conserved tryptophanyl residue changed the substrate specificity rendering a mutant protein capable of hydrolysing both alpha-(2,3) and alpha-(2,6)-linked sialoconjugates.
Food-restricted animals present metabolic adaptations that facilitate food-seeking behavior and d... more Food-restricted animals present metabolic adaptations that facilitate food-seeking behavior and decelerate energy utilization by reducing the hypothalamus-pituitary-thyroid (HPT) axis function. Stress by dehydration induces an anorexic behavior in rats, loss of weight and reduced food intake when compared to ad libitum fed animals, however these alterations are accompanied by HPT axis changes such as increased serum thyrotropin levels and enhanced expression of thyrotropin-releasing hormone (TRH) in the paraventricular nucleus of the hypothalamus, which is considered as anorexigenic peptide. In contrast, a pair-fed group conformed by forced-food-restricted animals (FFR) (eating the exact same amount of food as dehydration-induced anorexic rats-DIA rats) present decreased TRH mRNA levels. NPY synthesis in the arcuate nucleus and orexin-expressing neurons from the lateral hypothalamic area (LHA) are activated during food restriction. These brain structures project into PVN, suggesting that NPY and orexins are possible factors involved in TRHergic neuron activation in DIA rats. Leptin signaling is another likely factor to be involved in TRH differential expression. Therefore, to gain more insight into the regulation of the feeding behavior in the experimental models, we analyzed Y1, Y5, Ox1-R and Ob-R b mRNA levels in PVN and preproorexin in LHA, since their signaling to the PVN might be altering TRH synthesis and feeding in DIA animals. Prepro-orexinergic cells were activated in FFR animals; Ox1-R and Y1 expression was reduced in FFR vs. controls or DIA group. Compensatory changes in PVN receptor expression of some feeding-related peptides in anorexic rats may alter TRHergic neural response to energy demands.
Wistar rats subjected to dehydration-induced anorexia (DIA), with 2.5% NaCl solution as drinking ... more Wistar rats subjected to dehydration-induced anorexia (DIA), with 2.5% NaCl solution as drinking water for 7 days, decrease by 80% their food intake and present some changes common to pair-fed food restricted rats (FFR) such as: weight loss, decreased serum leptin and expression of orexigenic arcuate peptides, increasing the anorexigenic ones and serum corticosterone levels. In contrast, the response of the HPT axis differs: DIA animals have increased TRH expression in PVN and present primary as opposed to the tertiary hypothyroidism of the FFR. Exclusive to DIA is the activation of CRHergic neurons in the lateral hypothalamus (LH) that project to PVN. Since TRH neurons of the PVN contain CRH receptors, we hypothesized that the differences in the response of the HPT axis to DIA could be due to CRH regulating TRHergic neurons. CRH effect was first evaluated on TRH expression of cultured hypothalamic cells where TRH mRNA levels increased after 1h with 0.1nM of CRH. We then measured the mRNA levels of CRH receptors in the PVN of male and female rats subjected to DIA; only those of CRH-R2 were modulated (down-regulated). The CRH-R2 antagonist antisauvagine-30 was therefore injected into the PVN of male rats, during the 7 days of DIA. Antisauvagine-30 induced a higher food intake than controls, and impeded the changes produced by DIA on the HPT axis: PVN TRH mRNA, and serum TH and TSH levels were decreased to similar values of FFR animals. Results corroborate the anorexigenic effect of CRH and show its role, acting through CRH-R2 receptors, in the activation of TRHergic PVN neurons caused by DIA. These new data further supports clinical trials with CRH-R2 antagonists in anorexia nervosa patients.
Alcohol drinking and tobacco smoking are assumed to have significant independent and joint effect... more Alcohol drinking and tobacco smoking are assumed to have significant independent and joint effects on oral cancer (OC) development. This assumption is based on consistent reports from observational studies, which, however, overestimated the independent effects of smoking and drinking, because they did not account for the interaction effect in multivariable analyses. This case-control study sought to investigate the independent and the joint effects of smoking and drinking on OC in a homogeneous sample of adults. Case patients (N = 1,144) were affected by invasive oral/oropharyngeal squamous cell carcinoma confirmed histologically, diagnosed between 1998 and 2008 in four hospitals of São Paulo (Brazil). Control patients (N = 1,661) were not affected by drinking-, smoking-associated diseases, cancers, upper aero-digestive tract diseases. Cumulative tobacco and alcohol consumptions were assessed anamnestically. Patients were categorized into never/ever users and never/level-1/level-2 users, according to the median consumption level in controls. The effects of smoking and drinking on OC adjusted for age, gender, schooling level were assessed using logistic regression analysis; Model-1 did not account for the smoking-drinking interaction; Model-2 accounted for this interaction and included the resultant interaction terms. The models were compared using the likelihood ratio test. According to Model-1, the adjusted odds ratios (ORs) for smoking, drinking, smoking-drinking were 3.50 (95% confidence interval-95CI, 2.76-4.44), 3.60 (95CI, 2.86-4.53), 12.60 (95CI, 7.89-20.13), respectively. According to Model-2 these figures were 1.41 (95CI, 1.02-1.96), 0.78 (95CI, 0.48-1.27), 8.16 (95CI, 2.09-31.78). Analogous results were obtained using three levels of exposure to smoking and drinking. Model-2 showed statistically significant better goodness-of-fit statistics than Model-1. Drinking was not independently associated with OC, while the independent effect of smoking was lower than expected, suggesting that observational studies should be revised adequately accounting for the smoking-drinking interaction. OC control policies should focus on addictive behaviours rather than on single lifestyle risk factors.
The MBT repeat has been recently identified as a key domain capable of methyl-lysine histone reco... more The MBT repeat has been recently identified as a key domain capable of methyl-lysine histone recognition. Functional work has pointed to a role for MBT domain-containing proteins in transcriptional repression of developmental control genes such as Hox genes. In this study, L3MBTL2, a human homolog of Drosophila Sfmbt critical for Hox gene silencing, is demonstrated to preferentially recognize lower methylation states of several histone-derived peptides through its fourth MBT repeat. High-resolution crystallographic analysis of the four MBT repeats of this protein reveals its unique asymmetric rhomboid architecture, as well as binding mechanism, which preclude the interaction of the first three MBT repeats with methylated peptides. Structural elucidation of an L3MBTL2-H4K20me1 complex and comparison with other MBT-histone peptide complexes also suggests that an absence of distinct surface contours surrounding the methyl-lysine-binding pocket may underlie the lack of sequence specificity observed for members of this protein family.
Background: The insular cortex (IC) receives somatosensory afferent input and has been related to... more Background: The insular cortex (IC) receives somatosensory afferent input and has been related to nociceptive input. It has dopaminergic terminals and D1 (D1R) -excitatory- and D2 (D2R) -inhibitory- receptors. D2R activation with a selective agonist, as well as D1R blockade with antagonists in the IC, diminish neuropathic nociception in a nerve transection model. An intraplantar injection of carrageenan and acute thermonociception (plantar test) were performed to measure the response to inflammation (paw withdrawal latency, PWL). Simultaneously, a freely moving microdyalisis technique and HPLC were used to measure the release of dopamine and its metabolites in the IC. Plantar test was applied prior, one and three hours after inflammation. Also, mRNA levels of D1 and D2R's were measured in the IC after three hours of inflammation. Results: The results showed a gradual decrease in the release of dopamine, Dopac and HVA after inflammation. The decrease correlates with a decrease in...
Modified sialic acid substrates have been used to label Trypanosoma cruzi trans-sialidase, demons... more Modified sialic acid substrates have been used to label Trypanosoma cruzi trans-sialidase, demonstrating that the enzyme catalyses the transfer of sialic acid through a covalent glycosyl-enzyme intermediate, a mechanism common to most retaining glycosidases. Peptic digestion of labeled protein, followed by LC-MS/MS analysis of the digest, identified Tyr342 as the catalytic nucleophile. This is the first such example of a retaining glycosidase utilizing an aryl glycoside intermediate. It is suggested that this alternative choice of nucleophile is a consequence of the chemical nature of sialic acid. A Tyr/Glu couple is invoked to relay charge from a remote glutamic acid, thereby avoiding electrostatic repulsion with the sialic acid carboxylate group.
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