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1.
Mymensingh Med J ; 29(1): 222-227, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31915362

RESUMO

Insulinoma is a rare variety of endocrine neoplasm and is usually benign, solitary, and small in size. The hallmark of this disorder is high endogenous insulin secretion resulting in development of symptoms of hypoglycemia. Insulinomas account for 60% of islet cell tumors (ICT) of the pancreas. Ninety percent (90%) of the insulinomas measure less than 2cm. Early localization of the disease is essential to prevent lethal hypoglycemia. Here we report a case of insulinoma in a 28 year old female who subsequently underwent distal pancreatectomy with splenectomy on February 2017 in Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh.


Assuntos
Hipoglicemia , Insulinoma/cirurgia , Neoplasias Pancreáticas/cirurgia , Adulto , Bangladesh , Diabetes Mellitus Tipo 2/etiologia , Feminino , Humanos , Hiperinsulinismo/etiologia , Hipoglicemia/etiologia , Insulinoma/patologia , Pancreatectomia , Neoplasias Pancreáticas/patologia , Resultado do Tratamento
2.
J Bioenerg Biomembr ; 51(3): 203-218, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31030390

RESUMO

Direct and indirect evidences show that elevated glucose concentrations in airway surface liquid (ASL) promote lung infection by pathogens, playing a role in the progression of the Cystic Fibrosis (CF) disease. The joint action of transporter/s for glucose and of the cellular enzymes is essential in order to try to lower ASL glucose level. Inside the cell, the glycolysis and the pentose phosphate pathway (PPP) compete for the utilization of glucose-6-phosphate (G6P), the product in which glucose, after entry within the cell and phosphorylation, is trapped. The study aims to clarify whether, modulating the activity of enzymatic proteins and/or the level of metabolites/cofactors, involved in intracellular glucose utilization, a lowering of the extracellular glucose level in CF occurs. Biochemical approaches have enabled us to understand i) how G6P is shunted between glycolysis and PPP and ii) that mitochondria, more than enzymes/cofactors participating to the two cell glucose utilization pathways, are protagonists of the scene in counteracting the high ASL glucose level as well as oxidative stress in CF.


Assuntos
Fibrose Cística/metabolismo , Glucose-6-Fosfato/metabolismo , Glucose/metabolismo , Mitocôndrias/metabolismo , Estresse Oxidativo , Via de Pentose Fosfato , Linhagem Celular Tumoral , Fibrose Cística/patologia , Humanos , Mitocôndrias/patologia
3.
J Bioenerg Biomembr ; 50(2): 117-129, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29524019

RESUMO

Cystic fibrosis (CF) is associated to impaired Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel also causing decreased glutathione (GSH) secretion, defective airway bacterial clearance and inflammation. Here we checked the main ROS-producing and ROS-scavenging enzymes as potential additional factors involved in CF pathogenesis. We found that CFBE41o-cells, expressing F508del CFTR, have increased NADPH oxidase (NOX) activity and expression level, mainly responsible of the increased ROS production, and decreased glutathione reductase (GR) activity, not dependent on GR protein level decrease. Furthermore, defective CFTR proved to cause both extracellular and intracellular GSH level decrease, probably by reducing the amount of extracellular GSH-derived cysteine required for cytosolic GSH synthesis. Importantly, we provide evidence that defective CFTR and NOX/GR activity imbalance both contribute to NADPH and GSH level decrease and ROS overproduction in CF cells.


Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística/genética , Fibrose Cística/fisiopatologia , Glutationa Redutase/metabolismo , NADPH Oxidases/metabolismo , Estresse Oxidativo , Linhagem Celular , Fibrose Cística/enzimologia , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Glutationa/metabolismo , Humanos , NADP/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sistema Respiratório/fisiopatologia
4.
Dalton Trans ; 46(20): 6514-6517, 2017 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-28426054

RESUMO

Chiral clusters with MnIIMnNaI and the new MnIIMnNa cores have been synthesised employing enantiomerically pure Schiff bases and halide ligands. The new compounds have been characterized by electronic circular dichroism (ECD) and magnetic susceptibility.

5.
Front Psychol ; 6: 2050, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26793158

RESUMO

Humans and other social animals interact regularly with conspecifics as part of affiliative groups. Many of these interactions are cooperative, but many others involve competition for resources. Competitive exchanges are often resolved on the basis of dominance relationships, with higher-ranking individuals receiving priority access to desired goods. Although no single cue can establish permanent dominance relationships, there are some cues that predict dominance fairly reliably across context. In the present study, we focused on two such cues relevant to competing groups: (i) the physical sizes of individual members, and (ii) their relative number. Using a social competition task, we examined whether, and how, preschool-aged children and adults used differences in physical size and numerical alliances to judge which of two groups should prevail in a competitive exchange for a desired object. These judgments were made when either physical size or number differed between groups (Experiment 1), and when both were available but pitted against each other (Experiments 1 and 2). Our findings revealed that by 3 years of age, humans use multiple perceptible cues in third-party judgments of dominance. Our findings also revealed that 3-year-olds, like adults, weighted these cues flexibly according to the additional factor of overall group size, with the physical sizes of individuals determining dominance in smaller groups (e.g., 2 vs. 4 characters) and the relative number of individuals determining dominance in larger groups (e.g., 15 vs. 30 characters). Taken together, our findings suggest that a basic formula for determining dominance in competitive exchanges, which weights physical size of individuals and numerical alliances as a function of overall group size, is available to young children and appears fairly stable through to adulthood.

6.
Am J Clin Oncol ; 34(5): 529-36, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20838323

RESUMO

During breast cancer radiotherapy, nearly all patients will experience radiodermatitis. Study objectives were as follows: (1) systematically review the literature on radiodermatitis and breast cancer; (2) summarize and describe patient-rated radiodermatitis measures; (3) determine whether consensus exists regarding subjective radiodermatitis measurement; and (4) provide recommendations for future research. PubMed and CINAHL were searched from their inception through August 2009. Study inclusion and exclusion criteria were: full abstract available, manuscript in English, focused on radiodermatitis resulting from breast cancer radiotherapy, and described a patient-rated empirical assessment of radiodermatitis. Three reviewers examined abstracts, and decisions about inclusion were reached by consensus. Twenty-two of 237 mutually identified studies met selection criteria. Using a standardized abstraction form, 3 authors independently extracted relevant information. Results indicated that (1) only 9% of the studies reviewed included a patient-rated measure; (2) generally, extant scales are very brief and focus almost exclusively on physical reactions, and (3) there is no "gold standard" measure of patient-rated radiodermatitis at this time. We conclude that significantly more research is needed to determine the best (most valid, reliable, sensitive, comprehensive) measure(s) to evaluate the experience of radiodermatitis from the patient's perspective, and that further scale development efforts are needed.


Assuntos
Braquiterapia/efeitos adversos , Neoplasias da Mama/complicações , Neoplasias da Mama/radioterapia , Radiodermite/etiologia , Feminino , Humanos
7.
J Pharm Biomed Anal ; 52(4): 479-83, 2010 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-20185265

RESUMO

Kavalactones represent the active constituents of kava-kava (Piper methysticum G. Forster), endowed with sedative and anaesthetic properties. Kavalactones are polar constituents, but poorly soluble in water with a low bioavailability. In this study, the formation of inclusion complexes of one of the most representative kavalactone isolated from kava-kava extract, (S)-7,8-dihydrokavain (DHK), with beta-cyclodextrin (beta-CyD) was investigated mainly by spectroscopic methods. NMR experiments were extensively used for the complete characterization of the complex and included (1)H NMR complexation shifts analysis, (1)H NMR diffusion measurements (DOSY), and ROESY experiments. In particular DOSY experiments demonstrated that in the presence of beta-CyD the translational diffusion of kavalactone is sizably slowed down (2.5x10(-10)m(2)/s) with respect to the free drug (4.4x10(-10)m(2)/s) according to the inclusion of DHK in the cavity of (beta-CyD). ROESY experiments confirmed the inclusion of DHK in the hydrophobic pocket of beta-CyD through the primary hydroxyl rim, being the most relevant interactions between the H3' of beta-CyD and the ortho protons on the phenyl ring of the DHK, and between H5' of beta-CyD and the meta/para protons of DHK phenyl ring. The inclusion of the phenyl ring of DHK, leaving the lactone moiety outside of CyD was also confirmed by the induced CD effects. The binary solution DHK/beta-CyD shows a 50% intensity increase of the negative band of the pi-pi* transitions of the phenyl ring with respect to the absorption observed with DHK alone. Molecular dynamics simulations results corroborated and further clarify observed spectroscopic data. It was found that the phenylethyl substituent at C6 has a preferential equatorial position in the free state, and an axial one in the complex, justifying the large downfield shift experienced by H6 of DHK upon binding. Finally the influence of beta-CyD on water solubility of DHK was investigated by phase-solubility studies. In the range 2-4mM of host, solubility of DHK was increased only two-fold, but being beta-CyD also a penetration enhancer, in vivo studies will be performed to clarify a possible role of the complex on the bioavailability of DHK.


Assuntos
Portadores de Fármacos/análise , Kava , Lactonas/análise , Pironas/análise , Água/análise , beta-Ciclodextrinas/análise , Cromatografia Líquida de Alta Pressão/métodos , Ciclodextrinas/análise , Ciclodextrinas/química , Portadores de Fármacos/química , Lactonas/química , Espectrometria de Massas/métodos , Pironas/química , Água/química , beta-Ciclodextrinas/química
8.
Biochim Biophys Acta ; 1777(10): 1289-300, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18725189

RESUMO

Having confirmed that adenovirus-mediated overexpression of NH(2)-tau fragment lacking the first 25 aminoacids evokes a potent neurotoxic effect, sustained by protracted stimulation of NMDA receptors, in primary neuronal cultures we investigated whether and how chemically synthesized NH(2)-derived tau peptides, i.e. NH(2)-26-44 and NH(2)-1-25 fragments, affect mitochondrial function. We tested both fragments on each step of the processes leading to ATP synthesis via oxidative phosphorylation: i) electron flow via the respiratory chain from physiological substrates to oxygen with the activity of each individual complex of the respiratory chain investigated in some detail, ii) membrane potential generation arising from externally added succinate and iii) the activity of both the adenine nucleotide translocator and iv) ATP synthase. Oxidative phosphorylation is not affected by NH(2)-1-25 tau fragment, but dramatically impaired by NH(2)-26-44 tau fragment. Both cytochrome c oxidase and the adenine nucleotide translocator are targets of NH(2)-26-44 tau fragment, but adenine nucleotide translocator is the unique mitochondrial target responsible for impairment of oxidative phosphorylation by the NH(2)-26-44 tau fragment, which then exerts deleterious effects on cellular availability of ATP synthesized into mitochondria.


Assuntos
Mitocôndrias/metabolismo , Translocases Mitocondriais de ADP e ATP/metabolismo , Fosforilação Oxidativa , Fragmentos de Peptídeos/metabolismo , Proteínas tau/metabolismo , Difosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Potencial da Membrana Mitocondrial/fisiologia , Mitocôndrias/química , Translocases Mitocondriais de ADP e ATP/genética , ATPases Mitocondriais Próton-Translocadoras/metabolismo , Consumo de Oxigênio , Fragmentos de Peptídeos/genética , Ratos , Ratos Wistar , Proteínas tau/genética
9.
Behav Res Ther ; 46(1): 48-61, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17988651

RESUMO

Although significant empirical support exists for both cognitive and neurobiological models of obsessive-compulsive disorder (OCD), there have been few efforts to integrate findings. In this investigation, we attempted to link models by examining relationships between performance on information processing tasks posited to be markers of OCD-related neuropathology and a self-report measure of excessive thought-focused attention (cognitive self-consciousness; CSC). Congruent with predictions and prior research, OCD patients' performance was impaired in comparison to an anxious control group on the Serial Reaction Time (SRT) Task, a measure of implicit procedural learning. Following completion of the SRT, participants' awareness of the embedded stimulus pattern was assessed. As predicted, participants with OCD demonstrated superior performance on this task. Scoring on a measure of CSC correlated with performance on both tasks, although the amount of variance accounted for was modest. Evaluation of OCD symptom subgroups revealed greater procedural learning impairment in a hoarding subgroup. Implications for theory and treatment are discussed.


Assuntos
Transtornos de Ansiedade/psicologia , Transtorno Obsessivo-Compulsivo/psicologia , Adulto , Transtornos de Ansiedade/terapia , Cognição/fisiologia , Feminino , Humanos , Masculino , Processos Mentais/fisiologia , Modelos Neurológicos , Testes Neuropsicológicos/normas , Transtorno Obsessivo-Compulsivo/terapia , Tempo de Reação/fisiologia , Autoavaliação (Psicologia) , Resultado do Tratamento
10.
Chirality ; 13(9): 548-55, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11579448

RESUMO

The conformation in solution of two atropisomeric meso-tetrabinaphthyl porphyrins, used as catalytic precursors in asymmetric synthesis, was studied by means of experimental ((1)H-NMR ROESY, UV-Vis, and circular dichroism) and computational (semiempirical structure optimization, DeVoe's coupled oscillators calculations) methods. UV-Vis and CD spectra are calculated for several molecular models, with a systematic sampling of the conformational space, and compared to the experimental ones, leading to a structural hypothesis which is confirmed by NMR and PM3.

11.
J Nat Prod ; 64(7): 892-5, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11473417

RESUMO

A new cyclohexenone (1) and a new caffeoyl ester derivative (2), together with the known compounds (-)-isolariciresinol 3-alpha-O-beta-D-glucopyranoside (3), (+)-1-hydroxypinoresinol 1-O-beta-D-glucopyranoside (4), isoacteoside (5), luteolin 4'-O-beta-D-glucopyranoside (6), and indole-3-carboxylic acid (7), were isolated from the leaves of Bauhinia tarapotensis. The structures of these new compounds were determined by spectroscopic data analysis. The antioxidant activities of 1-7 were determined by measuring their free radical scavenging effects, using the 1,1-diphenyl-2-dipicrylhydrazyl free radical (DPPH) and Trolox equivalent antioxidant activity (TEAC) methods, and the coupled oxidation of beta-carotene and linoleic acid. Compounds 3-5 showed good activities in the DPPH and TEAC tests, while compounds 1 and 2 were active in the coupled oxidation of beta-carotene and linoleic acid bioassay.


Assuntos
Antioxidantes/isolamento & purificação , Bepridil/análogos & derivados , Ácidos Cafeicos/isolamento & purificação , Cicloexanonas/isolamento & purificação , Fabaceae/química , Sequestradores de Radicais Livres/isolamento & purificação , Glucosídeos/isolamento & purificação , Luteolina , Fenóis , Picratos , Plantas Medicinais/química , Antioxidantes/química , Antioxidantes/farmacologia , Benzotiazóis , Bepridil/farmacologia , Compostos de Bifenilo , Ácidos Cafeicos/química , Ácidos Cafeicos/farmacologia , Cromanos/farmacologia , Cromatografia Líquida de Alta Pressão , Cicloexanonas/química , Cicloexanonas/farmacologia , Equador , Flavonoides/química , Flavonoides/isolamento & purificação , Flavonoides/farmacologia , Sequestradores de Radicais Livres/química , Sequestradores de Radicais Livres/farmacologia , Glucosídeos/química , Glucosídeos/farmacologia , Indóis/química , Indóis/isolamento & purificação , Indóis/farmacologia , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Folhas de Planta/química , Ácidos Sulfônicos/química
12.
J Org Chem ; 66(14): 4819-25, 2001 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-11442411

RESUMO

The method employing dimolybdenum tetraacetate for the assignment of the absolute configuration of optically active 1,2-diols is thoroughly revisited and applied to several compounds, some of which were synthesized by asymmetric cis-dihydroxylation. No exceptions were found to the empirical rule relating the sign of the induced CD spectrum and the configuration of the substrate, whatever its structure and sterical requirements. To broaden the scope of the method, its applicability to critical situations commonly encountered with synthetic products is tested. It is demonstrated that the method can be applied on samples with low chemical and optical purity, and that it may lend itself as a means to estimate the ee. The roles of the water content of the sample and of the diol-to-dimolybdenum ratio are investigated.


Assuntos
Glicóis/química , Dicroísmo Circular , Molibdênio , Compostos Organometálicos , Estereoisomerismo
13.
Blood Coagul Fibrinolysis ; 11(2): 175-82, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10759011

RESUMO

Many hemostatic and fibrinolytic parameters have been evaluated following hormone replacement therapy (HRT) but little is known about its influence on the anticoagulant response to activated protein C (APC-sensitivity). For this purpose, we studied the effect of transdermal 17-beta-estradiol (50 microg/24 h) by a continuous regimen on the APC-sensitivity, in 28 postmenopausal hysterectomized women (mean age, 47 years; range, 44-65 years). We also measured the plasma proteins directly involved in the protein C anticoagulant pathway, such as activities of factor VIII (VIII:C), factor V and free protein S. Von Willebrand factor (vWF) antigen, the carrier protein of factor VIII, was also determined. Blood sampling was done at baseline and after 16-week therapy. A significant increase in the normalized APC-sensitivity ratio (n-APC-SR) values (mean +/- SD: pre-trial, 0.88 +/- 0.14; post-trial, 1.01 +/- 0.12; P < 0.001) and a significant decrease of factor VIII:C plasma levels (pre-trial, 1.13 +/- 0.29 IU/ml; post-trial, 0.98 +/- 0.20 IU/ ml; P = 0.001) were found. No difference was observed in factor V, protein S and vWF plasma levels. Correlation studies demonstrated only a significant negative correlation between the percent change in n-APC-SR and the percent change in factor VIII:C (r = -0.574; P = 0.001). Our findings clearly show that HRT with transdermal estradiol improves the anticoagulant response to APC, probably as a result of a decreased factor VIII:C. We also suggest that a similar but opposite mechanism may occur for perorally administered estrogens used in the HRT. These results may have some clinical implications about the reported increase of the risk for venous thromboembolism following HRT.


Assuntos
Resistência à Proteína C Ativada/sangue , Estradiol/farmacologia , Terapia de Reposição Hormonal , Pós-Menopausa/sangue , Administração Cutânea , Adulto , Idoso , Análise de Variância , Antígenos/sangue , Estradiol/uso terapêutico , Estudos de Avaliação como Assunto , Fator V/metabolismo , Fator VIII/metabolismo , Feminino , Humanos , Histerectomia , Pessoa de Meia-Idade , Proteína S/metabolismo , Fator de von Willebrand/imunologia
15.
Blood Coagul Fibrinolysis ; 10(1): 33-8, 1999 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10070833

RESUMO

Recent studies have shown that treatment with a continuous infusion of recombinant activated factor VII (rFVIIa) is far more convenient than administration by bolus intermittent injections and may allow a substantial reduction in the dose. We present the case of a 26-year-old patient with hemophilia A, who had a high-titer inhibitor to both human and porcine factor VIII, and who had recently been admitted to hospital because of a bilateral severe ilio-psoas hematoma. Two subsequent courses of treatment with rFVIIa by bolus intermittent injection showed only a partial efficacy. A further administration of rFVIIa was therefore carried out using a continuous infusion regimen that proved to be fully efficacious. During the continuous infusion course levels of factor VII coagulant activity were in the range 18.2-5.2 U/ml, while the prothrombin time, expressed as an International Normalized Ratio, remained within the range 0.57-0.71. The continuous infusion, compared with the administration of the bolus intermittent infusion, reduced the amount of rFVIIa required by approximately 40-50%. Statistical analysis demonstrated that there was a strong positive correlation between the rate of infusion of rFVIIa and levels of factor VII coagulant activity (r = +0.941; P < 0.001), and a very significant negative correlation between levels of factor VII coagulant activity and prothrombin time values (r = -0.897; P < 0.001). In accordance with previous findings, our experience confirms that, when prolonged therapy is required, treatment with rFVIIa by continuous infusion is more convenient than administration of bolus intermittent injections, and may allow the saving of a large amount of drug. Moreover, we suggest potential additional advantages of the continuous infusion regimen over bolus intermittent injections, such as a better efficacy and a stronger correlation between prothrombin time and factor VII coagulant activity levels.


Assuntos
Fator VIIa/administração & dosagem , Hemofilia A/tratamento farmacológico , Adulto , Anticorpos/sangue , Fator VIIa/imunologia , Hemofilia A/sangue , Hemofilia A/imunologia , Humanos , Infusões Intravenosas , Injeções Intravenosas , Masculino , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/imunologia
16.
Blood Coagul Fibrinolysis ; 10(7): 409-16, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10695766

RESUMO

High factor VIII plasma levels have been shown to represent a common increased risk for venous thromboembolism (VTE) and may cause an activated protein C (APC) resistance in the absence of the factor V Leiden mutation, but there are no studies specifically aimed to establish if high factor VIII and von Willebrand factor (vWF) concentrations may influence the APC sensitivity ratio (APC-SR) and increase the risk for VTE in the presence of the factor V Leiden mutation. For this purpose, we performed a retrospective case-control study to investigate the influence of the procoagulant factor VIII (VIII:C) and the antigen of vWF (vWF:Ag) on the normalized APC-SR (n-APC-SR) and on the risk for VTE, in two selected groups of 30 symptomatic (Group I) and 32 asymptomatic (Group II) related heterozygotes for the factor V Leiden mutation. Differences between the two groups (Group I versus Group II) were: n-APC-SR, 0.57+/-0.06 versus 0.63+/-0.08, P = 0.001; factor VIII:C, 1.49+/-0.42 versus 1.13+/-0.28 IU/ml, P<0.001; vWF:Ag, 1.46+/-0.53 versus 1.26+/-0.32 IU/ml, NS. As a whole (Group I + Group II), Pearson correlation coefficients were: n-APC-SR versus factor VIII:C, r = -0.410, P = 0.001; n-APC-SR versus vWF:Ag, r = -0.309, P = 0.01; factor VIII:C versus vWF:Ag, r = +0.640, P<0.0001. The relative risk for VTE in individuals with the factor VIII:C concentration > 1.5 IU/ml was 2.5 (95% confidence interval 1.6-3.9). We concluded that high factor VIII:C levels, probably in the effect of vWF, play a determinant role in worsening the APC-resistance phenotype and represent a common additional risk factor for VTE in heterozygous carriers of the factor V Leiden mutation.


Assuntos
Fator VIII/metabolismo , Fator V/genética , Proteína C/metabolismo , Trombose Venosa , Fator de von Willebrand/metabolismo , Adulto , Feminino , Heterozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Risco , Fatores de Risco , Trombose Venosa/sangue , Trombose Venosa/etiologia , Trombose Venosa/genética
17.
Enantiomer ; 3(4-5): 371-81, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9861703

RESUMO

The spectroscopic characterization of protein secondary structure is often partially unreliable when samples are not extremely pure and abundant. This problem may be overcome by the combination of circular dichroism (CD) and Fourier transform infrared spectroscopy (FT-IR). We used these methods to characterize the secondary structure of two proteins of neurobiological interest, calexcitin (CE) and the cellular isoform of prion protein (PrPC). Both proteins were purified with multiple chromatographic steps and were obtained in buffer with high purity (> 95%) and in low amount (approximately 2 micrograms). The samples were analyzed by circular dichroism (down to 184 or 182 nm), recovered, and deposited on films for infrared analysis. The spectral deconvolution from the two methods yielded secondary structures in good agreement with each other as well as with theoretical predictions based on amino acid sequence. The conformation of CE was found to be dependent on its concentration and on calcium binding. The secondary structure of cellular native PrP varied dramatically with the detergent used. In conclusion, the combination of CD and FT-IR analysis is suitable for the characterization of the conformational changes induced by ligand binding and/or by different solvent conditions when the protein of interest is only scarcely available. The methods used here provide valuable insights into the putative correlation between protein structure and activity.


Assuntos
Proteínas de Ligação ao Cálcio/química , GTP Fosfo-Hidrolases/química , Proteínas de Ligação ao GTP/química , Príons/química , Estrutura Secundária de Proteína , Algoritmos , Sequência de Aminoácidos , Animais , Proteínas de Caenorhabditis elegans , Cálcio/química , Cromatografia Líquida de Alta Pressão , Dicroísmo Circular , Cricetinae , Decapodiformes , Detergentes/química , Eletroforese em Gel de Poliacrilamida , Cromatografia Gasosa-Espectrometria de Massas , Glucosídeos/química , Dados de Sequência Molecular , Espectroscopia de Infravermelho com Transformada de Fourier
18.
Int J Obes Relat Metab Disord ; 21(7): 527-535, 1997 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-9226481

RESUMO

OBJECTIVES: To examine the relationship of obesity, body fat distribution, and fasting plasma insulin concentrations with the plasma levels of both pro-thrombotic and anti-thrombotic factors in premenopausal women. SUBJECTS: 32 obese women with BMI > 28 and 33 age-matched non-obese = women with BMI < 25. MEASUREMENTS: (i) plasma concentrations of plasminogen activator inhibitor-1 antigen (PAI-1 Ag), plasminogen activator inhibitor-1 activity (PAI-1 activity), fibrinogen, von Willebrand factor antigen (vWF Ag), von Willebrand factor activity (vWF activity), and factor VII activity as pro-thrombotic factors; (ii) plasma concentrations of tissue plasminogen activator antigen (t-PA Ag), protein C, and antithrombin III as anti-thrombotic factors; (iii) fasting plasma insulin and glucose concentrations, and the lipid pattern (triglycerides, total and HDL-cholesterol) as metabolic parameters. The body fat distribution was evaluated by measuring the waist circumference and the waist-to-hip ratio (WHR). RESULTS: Obese subjects had higher plasma concentrations of all pro-thrombotic factors as compared to non-obese controls (PAI-1 Ag, P < 0.001; PAI-1 activity, P < 0.05; fibrinogen, P < 0.001; vWF Ag, P < 0.001; vWF activity, P < 0.05; factor VII, P < 0.05). The plasma concentrations of PAI-1 Ag and vWF Ag were directly correlated with the waist circumference independently of other metabolic and non-metabolic variables (P < 0.05). Obese women were also characterized by higher plasma concentrations of anti-thrombotic factors such as t-PA Ag and protein C as compared to non-obese controls (P < 0.001 and P < 0.001, respectively), although these factors were not independently correlated with the waist circumference or the WHR. CONCLUSION: Plasma concentrations of the pro-thrombotic factors are increased in obese women as compared to non-obese controls, and plasma levels of PAI-1 Ag and vWF Ag correlate with central fat accumulation specifically. Plasma concentrations of anti-thrombotic factors (namely protein C and t-PA Ag) are also raised in obese women, but they are not correlated with parameters of body fat distribution. The increase in protein C levels may represent a protective response partly counteracting the increase in pro-thrombotic factors in these individuals.


Assuntos
Tecido Adiposo , Antitrombinas/análise , Fatores de Coagulação Sanguínea/análise , Obesidade/sangue , Pré-Menopausa/sangue , Adolescente , Adulto , Glicemia/análise , Constituição Corporal , Estudos de Casos e Controles , Feminino , Humanos , Insulina/sangue , Lipídeos/sangue , Pessoa de Meia-Idade , Inibidor 1 de Ativador de Plasminogênio/sangue , Fator de von Willebrand/análise
19.
IEEE Trans Biomed Eng ; 43(11): 1062-72, 1996 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9214824

RESUMO

The paper describes the general characteristics of a newly developed nonconstant-flow generator for automatic ventilation of the lungs. It is known that the application of very high pressure to high internal resistance leads to a very stable flow, in that the flow itself is unaffected by external load (patient) variations. The stability of the flow means that the inspiratory process can be controlled by means of the ventilated volume, thus extending DIGIT utilization to high resistance patients. The modulation of the flow is implemented via a digital electromechanical system, which allows the ventilator functions to be accurately programmed. The desired flow waveform is obtained by means of a series of pneumatic valves, the apertures of which are digitally controlled. The design is innovative in that it allows the flow waveform in each of the ten digitalized time steps into which each inspiratory phase is divided to be both programmed and controlled. Other ventilators commercially available and currently in use do not have this functional capability, as they are all designed to model the integral flow of the inspiratory waveform without being able to modify the subunit time steps of a single inspiratory phase. The paper also discusses the results of fundamental tests concerning the performance characteristics of the ventilator.


Assuntos
Ventilação Pulmonar/fisiologia , Respiração Artificial/instrumentação , Respiração/fisiologia , Resistência das Vias Respiratórias , Dióxido de Carbono/sangue , Eletrônica , Desenho de Equipamento , Humanos , Unidades de Terapia Intensiva , Oxigênio/sangue , Pressão , Insuficiência Respiratória/terapia
20.
J Pharm Biomed Anal ; 13(9): 1087-93, 1995 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-8573632

RESUMO

5-Fluorouracil (FU) is an important and widely used antineoplastic drug that is carried in the serum by plasma proteins. Protein binding studies of this drug to human serum albumin (HSA) have been carried out by several spectroscopic techniques. Difference circular dichroism and UV studies provided information on the class of binding sites involved in the interaction. In particular, displacement experiments showed that FU has at least one secondary binding site in the coumarin binding area, but does not interact with the benzodiazepine binding area. Binding was also investigated by difference 1H NMR and by measuring the increase in the 19F NMR signal of FU when bound to HSA. Finally, evidence was obtained that chemical acetylation of Lys199 results in a decreased apparent binding affinity constant (nK) for FU. Such a modification is induced under physiological conditions by aspirin.


Assuntos
Antimetabólitos Antineoplásicos/metabolismo , Fluoruracila/metabolismo , Albumina Sérica/metabolismo , Acetilação , Dicroísmo Circular , Flúor/química , Humanos , Hidrogênio/química , Lisina/química , Espectroscopia de Ressonância Magnética , Ligação Proteica/efeitos dos fármacos , Espectrofotometria Ultravioleta
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