RESUMO
The influence, on arsenic (As) urinary metabolic profile, of the level of As exposure was evaluated on chronic-exposed inhabitants of several locations of the Chaco-Pampean Plains in Argentina. Urinary As (UAs) was quantified as a measure of the level of exposure. The metabolic profile of UAs (inorganic As, monomethylarsonic acid, and dimethylarsinic acid) was also evaluated. The presence of T860C polymorphism on the arsenite methyltransferase encoding gene was investigated by desquamation of buccal cells. UAs showed a wide range of levels (from 18 µg/g to 4103 µg/g) of creatinine. A clear influence of age, gender, level of As exposure, and the presence of T860C polymorphism was observed on As metabolic profile. The influence of the level of exposure showed to be different between individuals carrying the wild type (WT) and the heterozygous (H) genotypes. Metabolic profile of individuals carrying the WT genotype seemed to be influenced by the level of exposure, while individuals with the H genotype did not. It is concluded that the level of As exposure seemed to have a significant influence on urinary metabolic profile of individuals carrying the WT genotype. In contrast, individuals carrying the H genotype seemed not to be affected the same way by increasing the As exposure level.
Assuntos
Arsênio/urina , Metiltransferases/genética , Poluentes Químicos da Água/urina , Adolescente , Adulto , Argentina , Arsênio/análise , Arsenicais/urina , Ácido Cacodílico/urina , Criança , Água Potável/análise , Monitoramento Ambiental , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo Genético , Poluentes Químicos da Água/análise , Adulto JovemRESUMO
UNLABELLED: Serial position effects are observed when a person memorises a series of words exceeding his or her attention span. Cognitively normal individuals recall words at the beginning and end of the list more frequently than those in the middle, which reflects the way that short- and long-term episodic memory works. OBJECTIVE: To study the serial position effect in patients with mild cognitive impairment (MCI) compared to subjects with Alzheimer-type dementia (AD) or normal ageing (NA). METHODS: 30 AD, 25 MCI and 20 NA subjects underwent neurological and neuropsychological assessment. The Rey Auditory Verbal Learning Test (RAVLT) was used to study primacy, middle, and recency effects and delayed recall for each group. RESULTS: The general memory pattern of MCI subjects was very similar to that of AD subjects, and was characterised by reduced learning capacity, rapid forgetfulness and clear recency effect in learning. With regard to delayed recall, however, there were differences in performance; MCI subjects' ability to recall words at the beginning and middle of the list was similar to that of normal subjects, while their memory of words at the end of the list was poor, as in AD subjects. CONCLUSIONS: RAVLT is a tool permitting us to distinguish between MCI and NA subjects. The recency index for the delayed recall task is a valid indicator for distinguishing between MCI patients and patients with normal ageing.
Assuntos
Envelhecimento/psicologia , Doença de Alzheimer/diagnóstico , Disfunção Cognitiva/diagnóstico , Testes Neuropsicológicos , Idoso , Atenção/fisiologia , Disfunção Cognitiva/psicologia , Diagnóstico Diferencial , Feminino , Humanos , Curva de Aprendizado , Masculino , Memória , Rememoração Mental , Reprodutibilidade dos TestesRESUMO
Lactic acid bacteria are the most adequate microorganisms for natural preservation of food. In the present work, the strain of Enterococcus faecalis CECT7121 was employed in the manufacture of craft dry-fermented sausages and its performance as a biopreservative was analysed. This strain is devoid of the genes for haemolysin and gelatinase and does not produce biogenic amines. It is sensitive to almost all the antibiotics tested and opsonophagocytic assays showed that it is devoid of a capsule. This strain had a high LD50 (10(11)CFU ml(-1)) in mice. No statistical differences were found between control and sausages inoculated with E. faecalis CECT7121 regarding the production of lactic acid, pH variation over time, reaching a minimum pH value of 5.1, and sensory analysis in both series. Sausages inoculated with E. faecalis CECT7121 had lower viable counts of Enterobacteriaceae, Staphylococcus aureus and other Gram-positive cocci at the end of fermentation and 7 days and no viable enterobacteria and S. aureus were recovered at the end of drying. E. faecalis CECT7121 did not affect the growth of Lactobacillus spp. but it displaced the autochthonous populations of enterococci. E. faecalis CECT7121 was recovered in each time point as assessed by its inhibitory activity on Listeria monocytogenes and S. aureus. These results would indicate that the addition of E. faecalis CECT7121 during the manufacture of craft dry-fermented sausages offers an interesting alternative for biopreservation.
Assuntos
Enterococcus faecalis/genética , Aditivos Alimentares , Conservantes de Alimentos , Produtos da Carne/microbiologia , Bacteriocinas/farmacologia , Aminas Biogênicas/análise , Contagem de Colônia Microbiana , Qualidade de Produtos para o Consumidor , Farmacorresistência Bacteriana/efeitos dos fármacos , Enterococcus faecalis/isolamento & purificação , Gelatinases/genética , Cocos Gram-Positivos/isolamento & purificação , Proteínas Hemolisinas/genética , Concentração de Íons de Hidrogênio , Ácido Láctico/metabolismo , Lactobacillus/isolamento & purificação , Lipase/metabolismo , Probióticos/farmacologia , Controle de Qualidade , Técnica de Amplificação ao Acaso de DNA Polimórfico , Staphylococcus aureus/isolamento & purificação , beta-Lactamases/metabolismoRESUMO
With the advent of fast imaging hardware and specialized software, additional non-invasive magnetic resonance characterization of tumors has become available through proton magnetic resonance spectroscopy (MRS), hemodynamic imaging and diffusion-weighted imaging (DWI). Thus, patterns could be discerned to discriminate different types of tumors and even to infer their possible evolution in time. The purpose of this study was to investigate the correlation between MRS, DWI, histopathology and Ki-67 labeling index in a large number of brain tumors. Localized proton spectra were obtained in 47 patients with brain tumors who subsequently underwent surgery (biopsy or tumor removal). We performed MRS with short echo-time (30 ms) and metabolic values in spectra were measured using an external software with 25 peaks. In all patients who had DWI, we measured apparent diffusion coefficients (ADC) in the same region of interest (ROI) where the voxel in MRS was located. In most tumors the histological diagnosis and Ki-67 labeling index had been determined on our original surgical specimen. Cho/Cr, (Lip+Mm)/Cr, NAA/(Cho+Cr) and Glx/Cr indexes in MRS allowed discriminating between low- and high-grade gliomas and metastases (MTs). Likewise, absolute ADC values differentiated low- from high-grade gliomas expressed by Ki-67 labeling index. A novel finding was that high Glx/Cr in vivo MRS index (similar to other known indexes) was a good predictor of tumor grading.
Assuntos
Ácido Aspártico/análogos & derivados , Neoplasias Encefálicas/diagnóstico , Antígeno Ki-67 , Adulto , Idoso , Ácido Aspártico/metabolismo , Neoplasias Encefálicas/química , Neoplasias Encefálicas/patologia , Proliferação de Células , Colina/metabolismo , Creatinina/metabolismo , Imagem de Difusão por Ressonância Magnética , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Metabolismo dos Lipídeos , Espectroscopia de Ressonância Magnética , Masculino , Pessoa de Meia-IdadeRESUMO
To evaluate whether pregnancy has a synergetic effect on the host's immune response against Trichinella spiralis infection, immunological and parasitological parameters relating to the infection were assessed in pregnant rats and compared to those observed in virgin infected rats. The muscle parasite load was lower in pregnant infected rats but no differences were found in the intestinal worm burdens or the fecundity of female worms. The ability of sera to mediate death in newborn larvae (NBL) in an antibody-dependent cell cytotoxicity assay was higher for pregnant rats, even in the absence of specific anti-NBL antibodies. High levels of total and anti-NBL IgE were found in both groups, however, these levels were higher in the group of pregnant infected animals. No differences were found in anti-NBL IgGAM titers, nevertheless in some pregnant infected rats these antibodies were found earlier. No differences were found in peritoneal or blood eosinophil counts. Offspring born to infected dams were found to be infected. The results obtained in this model demonstrate that during pregnancy there is an enhanced helminthotoxic effect towards the NBL. Despite this immunoactivation, vertical transmission of the parasite is possible.
Assuntos
Anti-Helmínticos/toxicidade , Complicações Parasitárias na Gravidez/imunologia , Trichinella spiralis/crescimento & desenvolvimento , Animais , Anticorpos Anti-Helmínticos/sangue , Modelos Animais de Doenças , Eosinófilos , Feminino , Imunoglobulina E/sangue , Larva/efeitos dos fármacos , Contagem de Leucócitos , Gravidez , Complicações Parasitárias na Gravidez/sangue , Ratos , Ratos Wistar , Reprodução , Fatores de Tempo , Trichinella spiralis/efeitos dos fármacos , Trichinella spiralis/patogenicidade , Triquinelose/sangue , Triquinelose/imunologiaRESUMO
Methanolic extracts from Achyrocline satureioides (Dc.) Lam, Aristolochia macroura Gomez, Lithraea molleoides (Vell.) Engl., Schinus molle L., unlike those from Celtis spinosa Spreng, Chenopodium ambrosioides L., Petiveria alliacea L., and Plantago major L. showed cytotoxic activity against a human hepatocellular carcinoma cell line, Hep G2. Schinus molle L. was the most active (IC50=50+/-7 microg/ml). These results call for further studies of these extracts.
Assuntos
Antineoplásicos/toxicidade , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/patologia , Inibidores do Crescimento/toxicidade , Plantas Medicinais/toxicidade , Anacardiaceae/toxicidade , Argentina , Aristolochia/toxicidade , Chenopodium/toxicidade , Relação Dose-Resposta a Droga , Humanos , Extratos Vegetais/toxicidade , Estruturas Vegetais , Plantago/toxicidade , Células Tumorais Cultivadas/efeitos dos fármacosRESUMO
Glucosamine-6P-deaminase (EC 3.5.99.6, formerly glucosamine-6-phosphate isomerase, EC 5.3.1.10) from Escherichia coli is an attractive experimental model for the study of allosteric transitions because it is both kinetically and structurally well-known, and follows rapid equilibrium random kinetics, so that the kinetic K(m) values are true thermodynamic equilibrium constants. The enzyme is a typical allosteric K-system activated by N-acetylglucosamine 6-P and displays an allosteric behavior that can be well described by the Monod-Wyman-Changeux model. This thermodynamic study based on the temperature dependence of allosteric parameters derived from this model shows that substrate binding and allosteric transition are both entropy-driven processes in E. coli GlcN6P deaminase. The analysis of this result in the light of the crystallographic structure of the enzyme implicates the active-site lid as the structural motif that could contribute significantly to this entropic component of the allosteric transition because of the remarkable change in its crystallographic B factors.
Assuntos
Acetilglucosamina/análogos & derivados , Aldose-Cetose Isomerases/química , Entropia , Escherichia coli/enzimologia , Acetilglucosamina/metabolismo , Aldose-Cetose Isomerases/metabolismo , Regulação Alostérica/fisiologia , Sítios de Ligação/fisiologia , Modelos Químicos , Ligação Proteica/fisiologia , Conformação Proteica , Relação Estrutura-Atividade , Especificidade por Substrato/fisiologia , Temperatura , TermodinâmicaRESUMO
Glucosamine-6-phosphate deaminase (EC 3.5.99.6) from Escherichia coli is an allosteric enzyme of the K-type, activated by N-acetylglucosamine 6-phosphate. It is a homohexamer and has six allosteric sites located in clefts between the subunits. The amino acid side-chains in the allosteric site involved in phosphate binding are Arg158, Lys160 and Ser151 from one subunit and the N-terminal amino group from the facing polypeptide chain. To study the functional role of the terminal amino group, we utilized a specific non-enzymic transamination reaction, and we further reduced the product with borohydride, to obtain the corresponding enzyme with a terminal hydroxy group. Several experimental controls were performed to assess the procedure, including reconditioning of the enzyme samples by refolding chromatography. Allosteric activation by N-acetylglucosamine 6-phosphate became of the K-V mixed type in the transaminated protein. Its kinetic study suggests that the allosteric equilibrium for this modified enzyme is displaced to the R state, with the consequent loss of co-operativity. The deaminase with a terminal hydroxy acid, obtained by reducing the transaminated enzyme, showed significant recovery of the catalytic activity and its allosteric activation pattern became similar to that found for the unmodified enzyme. It had lost, however, the pH-dependence of homotropic co-operativity shown by the unmodified deaminase in the pH range 6-8. These results show that the terminal amino group plays a part in the co-operativity of the enzyme and, more importantly, indicate that the loss of this co- operativity at low pH is due to the hydronation of this amino group.
Assuntos
Acetilglucosamina/análogos & derivados , Aldose-Cetose Isomerases/química , Aldose-Cetose Isomerases/metabolismo , Escherichia coli/enzimologia , Acetilglucosamina/metabolismo , Acetilglucosamina/farmacologia , Regulação Alostérica , Sítio Alostérico , Aminação , Boroidretos/metabolismo , Catálise/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Cinética , Metionina/metabolismo , Modelos Moleculares , Ligação Proteica , Dobramento de Proteína , Estrutura Quaternária de Proteína , Substâncias Redutoras/metabolismo , Relação Estrutura-Atividade , TermodinâmicaRESUMO
Previous reports indicate that malnutrition reduces reproductive functions. We have demonstrated that protein deprivation in the diet also causes reproductive dysfunction by reducing hypothalamic GnRH secretion. Noradrenaline and nitric oxide are modulators of GnRH secretion. Noradrenaline stimulates GnRH secretion and nitric oxide inhibits catecholamine release. This work studies the hypothalamic catecholaminergic and nitrergic neuron activity in Wistar adult male rats fed on an aproteic diet (AP) during 21 days; this treatment was started when rats were 70 days old. Our first experiment studied catecholamine turnover rate after inhibition of tyrosine hydroxylase activity by injecting (i.p.) 400 mg/kg alpha-methyl-p-tyrosine. Our second experiment studied in vitro hypothalamic nitric oxide synthase (NOS) activity in animals under the same diet. AP diet significantly decreased both noradrenaline (P<0.05) and dopamine (P<0.05) hypothalamic turnover rate. Noradrenaline turnover in cerebral cortex was not altered by the aproteic diet. However, hypothalamic NOS activity was not affected in animals fed on an AP diet. These results indicate that the lack of protein in the diet reduces catecholaminergic neuron activity in adult male rats by a NO-independent mechanism, thus suggesting that a decrease in noradrenergic activity may be involved in the reduction of GnRH secretion induced by an AP diet.
Assuntos
Córtex Cerebral/metabolismo , Dopamina/metabolismo , Hipotálamo/metabolismo , Norepinefrina/metabolismo , Desnutrição Proteico-Calórica/metabolismo , Animais , Masculino , Óxido Nítrico Sintase/metabolismo , Ratos , Ratos Wistar , Valores de Referência , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
N-Acetylglucosamine 6-phosphate deacetylase (E.C. 3.5.1.25), an enzyme from Escherichia coli involved in aminosugar catabolism, has been crystallized by the vapour-diffusion technique using phosphate as precipitant. X-ray diffraction experiments show the crystals to belong to the orthorhombic crystal system, with space group P2(1)2(1)2. The unit-cell parameters are a = 82.09 (2), b = 114.50 (1), c = 80.17 (1) A. The crystals diffract to a maximum resolution of 1.8 A and an initial data set was collected to 2.0 A.