Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 56
Filtrar
1.
J Biosoc Sci ; 56(2): 314-337, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37577970

RESUMO

Adolescence is a unique transitional stage of physical and psychological development. As preferences and behavioural choices adopted in adolescence influence lifelong physical activity habits and health outcomes in adulthood, rural transformation in low- and middle-income countries has the potential to significantly change traditional roles and shape the next generation. By using a mixed-method approach that integrates energy expenditure estimates from accelerometer devices with 24-hour recall time-use data from adolescent boys and girls and qualitative interviews with adolescents and their caregivers, this study sheds light on the patterns of quantity and quality of physical activity of 395 adolescents in Khammam and Mahbubnagar districts of rural Telangana, India. The study shows that energy expenditure and time use are highest for educational-related activities followed by leisure in both adolescent boys and girls. However, notwithstanding the process of rural transformation and the educational infrastructure and economic opportunities provided to adolescent boys and girls, social and cultural norms allow boys, especially in late adolescence to spend more time and energy in activities outside the home such as pursuing economic work, sports and socialising, while girls spend more time and energy at home doing domestic work. The quantitative and qualitative exploration of physical activity and time use among adolescents, as expounded in this study cutting across age groups and gender, highlights the need for changes in gendered norms and renewed government strategies and investments in that direction.


Assuntos
Identidade de Gênero , Esportes , Masculino , Feminino , Humanos , Adolescente , Escolaridade , População Rural , Exercício Físico
2.
Plant Cell Rep ; 30(4): 655-64, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21212958

RESUMO

Transgenic plants of tobacco (Nicotiana tabacum L) and European plum (Prunus domestica L) were produced by transforming with the apple class 1 KNOX genes (MdKN1 and MdKN2) or corn KNOX1 gene. Transgenic tobacco plants were regenerated in vitro from transformed leaf discs cultured in a medium lacking cytokinin. Ectopic expression of KNOX genes retarded shoot growth by suppressing elongation of internodes in transgenic tobacco plants. Expression of each of the three KNOX1 genes induced malformation and extensive lobbing in tobacco leaves. In situ regeneration of adventitious shoots was observed from leaves and roots of transgenic tobacco plants expressing each of the three KNOX genes. In vitro culture of leaf explants and internode sections excised from in vitro grown MdKN1 expressing tobacco shoots regenerated adventitious shoots on MS (Murashige and Skoog 1962) basal medium in the absence of exogenous cytokinin. Transgenic plum plants that expressed the MdKN2 or corn KNOX1 gene grew normally but MdKN1 caused a significant reduction in plant height, leaf shape and size and produced malformed curly leaves. A high frequency of adventitious shoot regeneration (96%) was observed in cultures of leaf explants excised from corn KNOX1-expressing transgenic plum shoots. In contrast to KNOX1-expressing tobacco, leaf and internode explants of corn KNOX1-expressing plum required synthetic cytokinin (thidiazuron) in the culture medium to induce adventitious shoot regeneration. The induction of high-frequency regeneration of adventitious shoots in vitro from leaves and stem internodal sections of plum through the ectopic expression of a KNOX1 gene is the first such report for a woody perennial fruit trees.


Assuntos
Nicotiana/crescimento & desenvolvimento , Brotos de Planta/crescimento & desenvolvimento , Prunus/crescimento & desenvolvimento , Proteínas de Homeodomínio/genética , Proteínas de Plantas/genética , Brotos de Planta/genética , Reação em Cadeia da Polimerase , Prunus/genética , Nicotiana/genética
3.
J Proteome Res ; 9(4): 1746-53, 2010 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-20131867

RESUMO

The human cannabinoid 1 receptor (hCB1), a ubiquitous G protein-coupled receptor (GPCR), transmits cannabinergic signals that participate in diverse (patho)physiological processes. Pharmacotherapeutic hCB1 targeting is considered a tractable approach for treating such prevalent diseases as obesity, mood disorders, and drug addiction. The hydrophobic nature of the transmembrane helices of hCB1 presents a formidable difficulty to its direct structural analysis. Comprehensive experimental characterization of functional hCB1 by mass spectrometry (MS) is essential to the targeting of affinity probes that can be used to define directly hCB1 binding domains using a ligand-assisted experimental approach. Such information would greatly facilitate the rational design of hCB1-selective agonists/antagonists with therapeutic potential. We report the first high-coverage MS analysis of the primary sequence of the functional hCB1 receptor, one of the few such comprehensive MS-based analyses of any GPCR. Recombinant C-terminal hexa-histidine-tagged hCB1 (His6-hCB1) was expressed in cultured insect (Spodoptera frugiperda) cells, solubilized by a procedure devised to enhance receptor purity following metal-affinity chromatography, desalted by buffer exchange, and digested in solution with (chymo)trypsin. "Bottom-up" nanoLC-MS/MS of the (chymo)tryptic digests afforded a degree of overall hCB1 coverage (>94%) thus far reported for only two other GPCRs. This MS-compatible procedure devised for His6-hCB1 sample preparation, incorporating in-solution (chymo)trypsin digestion in the presence of a low concentration of CYMAL-5 detergent, may be applicable to the MS-based proteomic characterization of other GPCRs. This work should help enable future ligand-assisted structural characterization of hCB1 binding motifs at the amino-acid level using rationally designed and targeted covalent cannabinergic probes.


Assuntos
Fragmentos de Peptídeos/metabolismo , Proteômica/métodos , Receptor CB1 de Canabinoide/química , Proteínas Recombinantes de Fusão/metabolismo , Espectrometria de Massas em Tandem/métodos , Sequência de Aminoácidos , Western Blotting , Desenho de Fármacos , Histidina/genética , Humanos , Interações Hidrofóbicas e Hidrofílicas , Dados de Sequência Molecular , Oligopeptídeos/genética , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Receptor CB1 de Canabinoide/genética , Receptor CB1 de Canabinoide/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Transdução de Sinais
4.
Sci Data ; 7(1): 71, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-32127539

RESUMO

With more than 820 million undernourished people living in rural areas of low- and middle-income countries (LMICs), ending hunger and ensuring access to food by all is a global priority. In the past few decades, the adoption of technological innovations in the agricultural sector and related crop yield improvements have not led to expected improvements in the nutritional status of rural households in many LMICs. The increased energy expenditure associated with the adoption of productivity-enhancing innovations may provide an important explanation of the disconnect between agricultural productivity enhancements and improved nutritional outcomes. We develop a methodology for generating reliable livelihood energy/calorie expenditure profiles for rural agricultural households using research-grade accelerometer devices. We integrate the data on physical activity and energy expenditure in rural households with data on time-use and food intakes to generate a data set that provides a unique window into rural livelihoods. This can be a valuable resource to analyse agriculture-nutrition impact pathways and improve the welfare of rural and agricultural households.


Assuntos
Agricultura , Ingestão de Alimentos , Exercício Físico , População Rural , Acelerometria , Eficiência , Metabolismo Energético , Características da Família , Gana , Humanos , Índia , Nepal , Estado Nutricional
5.
Econ Hum Biol ; 37: 100846, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31927034

RESUMO

Low and middle-income countries in Asia and Africa have been witnessing a process of rural transformation, characterised by rising agricultural productivity, commercialisation of agriculture, improved infrastructure and access to services, over several decades. However, there is little empirical evidence on how this transformation process has affected the patterns and intensity of physical activity and time use in rural livelihoods. The lack of empirical evidence can be attributed to the constraints in accurate measurement of physical activity and energy expenditure in the context of free-living populations. Using wearable accelerometry devices, we develop robust energy expenditure profiles for men and women in rural households for two case studies in India and Ghana. An innovative feature of this study is the integration of data on energy expenditure (derived from accelerometers) with data on time-use, which has hitherto not been feasible in observational studies of rural populations. Using the data on physical activity, energy expenditure and time use from the case studies, we examine the impact of drudgery reduction- the substitution of less intense for more intense activities - on energy requirements for men and women in rural households. Our results show that drudgery reduction can have large effects on human energy (calorie) requirements, with an hour of drudgery reduction reducing energy requirements by 11-22 % for men and 13-17 % for women in Ghana and India. There are significant gender differences in energy expenditure patterns and drudgery reduction effects vary by socio-demographic characteristics and endowments of households. Our results suggest that drudgery reduction can offer rural households an important route to improved nutritional status. At the same time, drudgery reduction can lead to increased incidence of overweight and obesity for some segments of the population. The design of development interventions needs to explicitly consider the effects on nutrition and well-being through the energy expenditure dimension.


Assuntos
Agricultura/estatística & dados numéricos , Metabolismo Energético/fisiologia , Exercício Físico/fisiologia , Fazendeiros , População Rural , Adulto , Países em Desenvolvimento , Ingestão de Energia , Feminino , Gana , Humanos , Índia , Masculino , Estado Nutricional , Fatores Sexuais , Fatores Socioeconômicos
6.
Chem Biol ; 15(8): 854-62, 2008 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-18721756

RESUMO

The active site of recombinant hexa-histidine-tagged human monoacylglycerol lipase (hMGL) is characterized by mass spectrometry using the inhibitors 5-((biphenyl-4-yl)methyl)-N,N-dimethyl-2H-tetrazole-2-carboxamide (AM6701), and N-arachidonylmaleimide (NAM) as probes. Carbamylation of Ser(129) by AM6701 in the putative hMGL catalytic triad demonstrates this residue's essential role in catalysis. Partial NAM alkylation of hMGL cysteine residues 215 and/or 249 was sufficient to achieve approximately 80% enzyme inhibition. Although Cys(215) and/or Cys(249) mutations to alanine(s) did not affect hMGL hydrolytic activity as compared with nonmutated hMGL, the C215A displayed heightened NAM sensitivity, whereas the C249A evidenced reduced NAM sensitivity. These data conclusively demonstrate a sulfhydryl-based mechanism for NAM inhibition of hMGL in which Cys(249) is of paramount importance. Identification of amino acids critical to the catalytic activity and pharmacological modulation of hMGL informs the design of selective MGL inhibitors as potential drugs.


Assuntos
Domínio Catalítico , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Monoacilglicerol Lipases/antagonistas & inibidores , Monoacilglicerol Lipases/química , Mutação , Amidas/química , Amidas/farmacologia , Sequência de Aminoácidos , Desenho de Fármacos , Humanos , Isomerismo , Ligantes , Maleimidas/química , Maleimidas/farmacologia , Espectrometria de Massas , Dados de Sequência Molecular , Monoacilglicerol Lipases/genética , Monoacilglicerol Lipases/metabolismo , Mutagênese Sítio-Dirigida
8.
Saudi J Anaesth ; 10(3): 359-61, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27375400

RESUMO

The main goals of neuroanesthesia are the maintenance of adequate cerebral perfusion pressure, avoidance of hypercarbia, hypoxemia, and to provide better brain relaxation. Providing anesthesia for a patient with bronchiectasis needing lung isolation for craniotomy can be challenging. A 56-year-old male patient, case of right lung bronchiectasis with a right cerebello pontine angle tumor underwent excision in the left lateral position. Since he had severe bronchiectasis of the right lung, we had isolated the right lung using right-sided double lumen tube to avoid spillage. Intraoperative split lung test was performed to assess the right lung contribution on carbon dioxide (CO2) elimination and found that there was a significant contribution from the right lung. Hence, both lungs were ventilated to control CO2. The importance of lung isolation to prevent spillage and avoidance of one lung ventilation to control the arterial CO2 are highlighted in this case report. By providing a balanced anesthetic keeping both, the neurosurgical and thoracic concerns are important for better postoperative outcome.

9.
PLoS One ; 11(9): e0162668, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27649080

RESUMO

In many developing countries, high levels of child undernutrition persist alongside rapid economic growth. There is considerable interest in the study of countries that have made rapid progress in child nutrition to uncover the driving forces behind these improvements. Cambodia is often cited as a success case having reduced the incidence of child stunting from 51% to 34% over the period 2000 to 2014. To what extent is this success driven by improvements in the underlying determinants of nutrition, such as wealth and education, ("covariate effects") and to what extent by changes in the strengths of association between these determinants and nutrition outcomes ("coefficient effects")? Using determinants derived from the widely-applied UNICEF framework for the analysis of child nutrition and data from four Demographic and Health Surveys datasets, we apply quantile regression based decomposition methods to quantify the covariate and coefficient effect contributions to this improvement in child nutrition. The method used in the study allows the covariate and coefficient effects to vary across the entire distribution of child nutrition outcomes. There are important differences in the drivers of improvements in child nutrition between severely stunted and moderately stunted children and between rural and urban areas. The translation of improvements in household endowments, characteristics and practices into improvements in child nutrition (the coefficient effects) may be influenced by macroeconomic shocks or other events such as natural calamities or civil disturbance and may vary substantially over different time periods. Our analysis also highlights the need to explicitly examine the contribution of targeted child health and nutrition interventions to improvements in child nutrition in developing countries.


Assuntos
Transtornos da Nutrição Infantil/prevenção & controle , Fenômenos Fisiológicos da Nutrição Infantil , Transtornos do Crescimento/prevenção & controle , Inquéritos Epidemiológicos/métodos , Análise de Variância , Camboja/epidemiologia , Criança , Transtornos da Nutrição Infantil/epidemiologia , Pré-Escolar , Comorbidade , Desenvolvimento Econômico/estatística & dados numéricos , Feminino , Transtornos do Crescimento/epidemiologia , Inquéritos Epidemiológicos/estatística & dados numéricos , Inquéritos Epidemiológicos/tendências , Humanos , Incidência , Lactente , Masculino , Estado Nutricional , Saúde da População Rural/estatística & dados numéricos , Fatores Socioeconômicos , Saúde da População Urbana/estatística & dados numéricos
10.
Curr Opin Chem Biol ; 2(2): 216-21, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9667925

RESUMO

Metal-responsive transcription factors exist in yeast to modulate expression of genes that encode proteins involved in cellular uptake of copper, iron and zinc ions. These signal transduction pathways function in the cellular regulation of the intracellular concentration of free metal ions. A second component of metal homeostasis is the regulation of metal-ion binding through protein-mediated metallation. Copper-specific chaperones exist in yeast that route copper ions to the site of biosynthesis of copper-metalloenzymes.


Assuntos
Regulação Fúngica da Expressão Gênica/genética , Metais/metabolismo , Saccharomyces cerevisiae/fisiologia , Cobre/metabolismo , Proteínas de Ligação a DNA/química , Ferro/metabolismo , Metaloproteínas/metabolismo , Fatores de Transcrição/genética , Zinco/metabolismo
11.
Biochem Pharmacol ; 61(2): 245-52, 2001 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-11163339

RESUMO

The cysteine (Cys) precursor 2(R,S)-n-propylthiazolidine-4(R)-carboxylic acid (PTCA) was shown previously to maintain near normal levels of hepatic GSH and GSSG at 24 hr and to protect against hepatic necrosis and mortality at 48 hr after toxic doses of acetaminophen (APAP) in mice. Studies were performed in C57BL/6 mice to determine: (a) the time course of APAP-induced hepatic sulfhydryl depletion, and (b) the effectiveness of PTCA in preventing APAP-induced decreases in sulfhydryl concentrations at the time of maximal depletion. APAP (400-800 mg/kg in 50% propylene glycol; 2.65-5.29 mmol/kg) and PTCA (1-5 mmol/kg 30 min after APAP) were administered i.p. Hepatic GSH, GSSG, and Cys concentrations were determined by HPLC. Hepatocellular damage was assessed by elevations in serum glutamate-pyruvate transaminase (SGPT) activity and histopathologic examination. APAP and PTCA produced dose-dependent effects. At 4 hr after the highest dose of APAP, hepatic GSH and Cys concentrations were reduced to 5 and 14%, respectively, of values in vehicle-treated controls, and the GSSG concentration was below the sensitivity of the analytical method. At 24 hr, recovery of hepatic sulfhydryls was incomplete, and there was hepatic necrosis with an approximately 100-fold increase in SGPT activity. At the highest dose of PTCA, the concentrations of GSH, Cys, and GSSG at 4 hr after APAP (800 mg/kg) were 66, 116, and 111%, respectively, of vehicle controls. PTCA in doses of 1.75 to 5 mmol/kg attenuated the APAP-induced increases in SGPT activity. It was concluded that the protective effect of PTCA is most likely related to prevention of hepatic sulfhydryl depletion.


Assuntos
Acetaminofen/antagonistas & inibidores , Hepatopatias/prevenção & controle , Tiazóis/farmacologia , Acetaminofen/toxicidade , Aldeídos/farmacologia , Analgésicos não Narcóticos/antagonistas & inibidores , Analgésicos não Narcóticos/toxicidade , Animais , Doença Hepática Induzida por Substâncias e Drogas , Cisteína/metabolismo , Relação Dose-Resposta a Droga , Interações Medicamentosas , Glutationa/metabolismo , Dissulfeto de Glutationa/metabolismo , Fígado/efeitos dos fármacos , Hepatopatias/metabolismo , Hepatopatias/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pró-Fármacos/uso terapêutico , Substâncias Protetoras/farmacologia
12.
Biochem Pharmacol ; 61(7): 925-31, 2001 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-11274980

RESUMO

The cysteine (Cys) precursor 2(RS)-n-propylthiazolidine-4(R)-carboxylic acid (PTCA) has been shown to protect against acetaminophen (APAP)-induced hepatic GSH, GSSG, and Cys depletion and hepatic necrosis. The aim of this study was to determine the effects of PTCA on the concentrations of sulfhydryl compounds in extrahepatic tissues, including renal cortex, whole blood, and brain, in C57BL/6 mice treated with hepatotoxic doses of APAP. PTCA (1-5 mmol/kg, i.p.) was administered 30 min after the administration of APAP at a dose (800 mg/kg; 5.29 mmol/kg, i.p.) that depleted hepatic GSH and Cys at 4 hr by 95 and 86%, respectively. Tissue concentrations of GSH and Cys were determined by HPLC. At 4 hr following APAP administration, renal cortical GSH and Cys concentrations were decreased to 64 and 39%, respectively, of vehicle-treated control values, and blood concentrations were decreased to 87 and 30%, respectively, of vehicle controls. Brain GSH and Cys were not depleted by APAP. PTCA at 5 mmol/kg (i) attenuated the APAP-induced depletion of GSH and Cys at 4 hr in renal cortex (78 and 65%, respectively, of vehicle controls), (ii) prevented APAP-induced Cys depletion in blood (670% of vehicle controls) with no effect on GSH concentration (94% of vehicle controls), and (iii) increased GSH and Cys concentrations in brain (119 and 411%, respectively, of vehicle controls). The results demonstrate a high degree of tissue selectivity in the APAP-induced depletion of GSH and Cys, and in the effectiveness of PTCA in maintaining and even elevating sulfhydryl levels in extrahepatic tissues of APAP-treated mice.


Assuntos
Acetaminofen/farmacologia , Córtex Renal/efeitos dos fármacos , Pró-Fármacos/farmacologia , Compostos de Sulfidrila/metabolismo , Tiazóis/farmacologia , Analgésicos não Narcóticos/farmacologia , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Cisteína/metabolismo , Interações Medicamentosas , Glutationa/deficiência , Glutationa/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Técnicas In Vitro , Córtex Renal/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Compostos de Sulfidrila/sangue , Distribuição Tecidual
13.
J Magn Reson ; 140(1): 206-17, 1999 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10479564

RESUMO

Evidence for competition between Li(+) and Na(+) for binding sites of human unsealed and cytoskeleton-depleted human red blood cell (csdRBC) membranes was obtained from the effect of added Li(+) upon the (23)Na double quantum filtered (DQF) and triple quantum filtered (TQF) NMR signals of Na(+)-containing red blood cell (RBC) membrane suspensions. We found that, at low ionic strength, the observed quenching effect of Li(+) on the (23)Na TQF and DQF signal intensity probed Li(+)/Na(+) competition for isotropic binding sites only. Membrane cytoskeleton depletion significantly decreased the isotropic signal intensity, strongly affecting the binding of Na(+) to isotropic membrane sites, but had no effect on Li(+)/Na(+) competition for those sites. Through the observed (23)Na DQF NMR spectra, which allow probing of both isotropic and anisotropic Na(+) motion, we found anisotropic membrane binding sites for Na(+) when the total ionic strength was higher than 40 mM. This is a consequence of ionic strength effects on the conformation of the cytoskeleton, in particular on the dimer-tetramer equilibrium of spectrin. The determinant involvement of the cytoskeleton in the anisotropy of Na(+) motion at the membrane surface was demonstrated by the isotropy of the DQF spectra of csdRBC membranes even at high ionic strength. Li(+) addition initially quenched the isotropic signal the most, indicating preferential Li(+)/Na(+) competition for the isotropic membrane sites. High ionic strength also increased the intensity of the anisotropic signal, due to its effect on the restructuring of the membrane cytoskeleton. Further Li(+) addition competed with Na(+) for those sites, quenching the anisotropic signal. (7)Li T(1) relaxation data for Li(+)-containing suspensions of unsealed and csdRBC membranes, in the absence and presence of Na(+) at low ionic strength, showed that cytoskeleton depletion does not affect the affinity of Na(+) for the RBC membrane, but increases the affinity of Li(+) by 50%. This clearly indicates that cytoskeleton depletion favors Li(+) relative to Na(+) binding, and thus Li(+)/Na(+) competition for its isotropic sites. Thus, this relaxation technique proves to be very sensitive to alkali metal binding to the membrane, detecting a more pronounced steric hindrance effect of the cytoskeleton network to binding of the larger hydrated Li(+) ion to the membrane phosphate groups.


Assuntos
Membrana Eritrocítica/metabolismo , Lítio/sangue , Espectroscopia de Ressonância Magnética , Sódio/sangue , Algoritmos , Ligação Competitiva , Distribuição de Qui-Quadrado , Análise de Fourier , Humanos , Análise dos Mínimos Quadrados
14.
J Magn Reson ; 157(2): 223-34, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12323141

RESUMO

The effect of an offset term in the cross-polarization (CP) Hamiltonian of a heteronuclear spin-12 pair due to off-resonant radio frequency (rf) irradiation and/or chemical shift anisotropy on one of the rf channels is investigated. Analytical solutions, simulations, and experimental results are presented. Formulating the CP spin dynamics in terms of an explicit unitary evolution operator enables the CP period to be inserted as a module in a given pulse scheme regardless of the initial density matrix present. The outcome of post-CP manipulation via pulses can be calculated on the resulting density matrix as the phases and amplitudes of all coherence modes are available. Using these tools it is shown that the offset can be used to reduce the rf power on that channel and the performance is further improved by a post-CP pulse whose flip angle matches and compensates the tilt of the effective field on the offset channel. Experimental investigations on single crystalline and polycrystalline samples of peptides confirm the oscillatory nature of CP dynamics and prove the slowing down of the dynamics under offset and/or mismatch conditions.

15.
J Org Chem ; 65(11): 3334-40, 2000 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-10843614

RESUMO

The selective oxidation of organic sulfides to sulfoxides by oxo(salen)chromium(V) complexes in acetonitrile is overall second-order, first-order each in the oxidant and the substrate. The rate constant, k(2), values of several para-substituted phenyl methyl sulfides correlate linearly with Hammett sigma constants and the rho values are in the range of -1.3 to -2.7 with different substituted oxo(salen)chromium(V) complexes. The reactivity of different alkyl sulfides is in accordance with Taft's steric substituent constant, E(S). A mechanism involving direct oxygen atom transfer from the oxidant to the substrate rather than electron transfer is envisaged. Correlation analyses show the presence of an inverse relationship between reactivity and selectivity in the reaction of various sulfides with a given oxo(salen)chromium(V) complex and vice versa. Mathematical treatment of the results shows that this redox system falls under strong reactivity-selectivity principle (RSP).

16.
Lipids ; 34(11): 1211-21, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10606045

RESUMO

The mode of action of the lithium ion (Li+) in the treatment of manic depression or bipolar illness is still under investigation, although this inorganic drug has been in clinical use for 50 yr. Several research reports have provided evidence for Li+/Mg2+ competition in biomolecules. We carried out this study to characterize the interactions of Li+ and Mg2+ with red blood cell (RBC) membrane components to see whether Li+/Mg2+ competition occurs. 31P nuclear magnetic resonance chemical shift measurements of the phospholipids extracted from the RBC membranes indicated that the anionic phospholipids, phosphatidylserine and phosphatidylinositol, bind Li+ and Mg2+ most strongly. From 6Li relaxation measurements, the Li+ binding constant to the phospholipid extract was found to be 45 +/- 5 M(-1). Thus, these studies showed that the phospholipids play a major role in metal ion binding. 7Li spin-lattice relaxation measurements conducted on unsealed and cytoskeleton-depleted RBC membrane in the presence of magnesium indicated that the removal of the cytoskeleton increases lithium binding to the more exposed anionic phospholipids (357 +/- 24 M(-1)) when compared to lithium binding in the unsealed RBC membrane (221 +/- 21 M(-1)). Therefore, it can be seen that the cytoskeleton does not play a major role in Li+ binding or in Li+/Mg2+ competition.


Assuntos
Membrana Eritrocítica/metabolismo , Lítio/sangue , Magnésio/sangue , Espectroscopia de Ressonância Magnética , Fosfolipídeos/sangue , Ânions , Ligação Competitiva , Citoesqueleto/fisiologia , Membrana Eritrocítica/ultraestrutura , Humanos , Cloreto de Lítio/administração & dosagem , Cloreto de Magnésio/administração & dosagem , Fosfatidilinositóis/sangue , Fosfatidilserinas/sangue
18.
Artigo em Inglês | MEDLINE | ID: mdl-18252305

RESUMO

An algorithm for computing three-dimensional (3-D) velocity field and motion parameters from a range image sequence is presented. It is based on a new integral 3-D rigid motion invariant feature-the trace of a 3x3 "feature matrix" related to the moment of inertia tensor. This trace can be computed at every point of a moving surface and provides a quantitative measure of the local shape of the surface. Based on the feature's conservation along the trajectory of every moving point, a 3-D Flow Constraint Equation is formulated and solved for the velocity field. The robustness of the feature in presence of noise and discontinuity is analyzed.

19.
Artigo em Inglês | MEDLINE | ID: mdl-15319128

RESUMO

To protect against malleolar fractures in frontal crashes it is important to understand the mechanisms of injury. We have investigated the accuracy of Orthopaedic Specialists in deducing the injury mechanisms of experimentally generated malleolar fractures from radiographs; and the applicability of classic descriptors of injury mechanisms, such as the Lauge-Hansen classification system, in analysing impact induced trauma. Orthopaedic Specialists did not consistently deduce the mechanism of ankle injuries suggesting there may not be a unique fracture pattern for every injury mechanism and that the Lauge-Hansen classification system does not reliably describe ankle fractures created in the impact environment.


Assuntos
Acidentes de Trânsito , Traumatismos do Tornozelo/fisiopatologia , Fraturas Ósseas/fisiopatologia , Traumatismos do Tornozelo/classificação , Traumatismos do Tornozelo/diagnóstico por imagem , Fenômenos Biomecânicos , Ligamentos Colaterais/diagnóstico por imagem , Ligamentos Colaterais/lesões , Fraturas Ósseas/classificação , Fraturas Ósseas/diagnóstico por imagem , Humanos , Movimento , Pronação , Radiografia , Estudos Retrospectivos , Supinação
20.
Econ Hum Biol ; 11(4): 574-91, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23665354

RESUMO

The facilitation of healthier dietary choices by consumers is a key element of government strategies to combat the rising incidence of obesity in developed and developing countries. Public health campaigns to promote healthier eating often target compliance with recommended dietary guidelines for consumption of individual nutrients such as fats and added sugars. This paper examines the association between improved compliance with dietary guidelines for individual nutrients and excess calorie intake, the most proximate determinant of obesity risk. We apply quantile regressions and counterfactual decompositions to cross-sectional data from the National Diet and Nutrition Survey (2000-01) to assess how excess calorie consumption patterns in the UK are likely to change with improved compliance with dietary guidelines. We find that the effects of compliance vary significantly across different quantiles of calorie consumption. Our results show that compliance with dietary guidelines for individual nutrients, even if successfully achieved, is likely to be associated with only modest shifts in excess calorie consumption patterns. Consequently, public health campaigns that target compliance with dietary guidelines for specific nutrients in isolation are unlikely to have a significant effect on the obesity risk faced by the population.


Assuntos
Dieta , Ingestão de Energia , Fidelidade a Diretrizes , Obesidade/prevenção & controle , Adulto , Estudos Transversais , Feminino , Humanos , Estilo de Vida , Masculino , Obesidade/epidemiologia , Reino Unido/epidemiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA