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‣ Nitrogen Metabolism in leaves of a tank epiphytic bromeliad: Characterization of a spatial and functional division

TAKAHASHI, Cassia Ayumi; MERCIER, Helenice
Fonte: ELSEVIER GMBH, URBAN & FISCHER VERLAG Publicador: ELSEVIER GMBH, URBAN & FISCHER VERLAG
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.237236%
The leaf is considered the most important vegetative organ of tank epiphytic bromeliads due to its ability to absorb and assimilate nutrients. However, little is known about the physiological characteristics of nutrient uptake and assimilation. In order to better understand the mechanisms utilized by some tank epiphytic bromeliads to optimize the nitrogen acquisition and assimilation, a study was proposed to verify the existence of a differential capacity to assimilate nitrogen in different leaf portions. The experiments were conducted using young plants of Vriesea gigantea. A nutrient solution containing NO(3)(-)/NH(4)(+) or urea as the sole nitrogen source was supplied to the tank of these plants and the activities of urease, nitrate reductase (NR), glutamine synthetase (GS) and glutamate dehydrogenase (NADH-GDH) were quantified in apical and basal leaf portions after 1, 3, 6, 9, 12, 24 and 48 h. The endogenous ammonium and urea contents were also analyzed. Independent of the nitrogen sources utilized, NR and urease activities were higher in the basal portions of leaves in all the period analyzed. On the contrary. GS and GDH activities were higher in apical part. It was also observed that the endogenous ammonium and urea had the highest contents detected in the basal region. These results suggest that the basal portion was preferentially involved in nitrate reduction and urea hydrolysis...

‣ Ractopamina, cromo-metionina e suas combinações como aditivos modificadores do metabolismo de suínos em crescimento e terminação; Ractopamine, chromium-methionine and their combinations as metabolism modifier feed additives of growing and finishing pigs

Almeida, Vivian Vezzoni de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 16/01/2009 Português
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37.341729%
O objetivo deste trabalho foi avaliar o efeito da ractopamina, cromo-metionina e suas combinações nas dietas de suínos em crescimento e terminação sobre o desempenho, as características de carcaça e a qualidade da carne. Sessenta e quatro suínos da linhagem Topigs, com peso médio inicial de 26,56 ± 3,11 kg, foram distribuídos em um delineamento experimental de blocos casualizados em esquema fatorial 2 x 2, sendo dois níveis de ractopamina (0 e 5 ppm) e dois níveis de cromo-metionina (0 e 400 ppb), perfazendo quatro tratamentos. Os tratamentos foram: C controle: dieta basal constituída por milho e farelo de soja; Rac ractopamina: dieta basal com a inclusão de 5 ppm de ractopamina dos 70,32 aos 114,80 kg de PV; Cr-Met cromometionina: dieta basal com a inclusão de 400 ppb de cromo-metionina dos 26,56 aos 114,80 kg de PV; Rac + Cr-Met ractopamina + cromo-metionina: dieta basal com a inclusão de 400 ppb de cromo-metionina dos 26,56 aos 114,80 kg de PV e 5 ppm de ractopamina dos 70,32 aos 114,80 kg de PV. Foram utilizados oito repetições (blocos) por tratamento e dois animais por unidade experimental (um macho castrado e uma fêmea). O período experimental foi dividido em três fases, de acordo com o peso dos animais: crescimento I: 26...

‣ Sinalização da indução do metabolismo ácido das crassuláceas (CAM) por ácido abscísico e óxido nítrico em Guzmania monostachia (Bromeliaceae); Abscisic acid and nitric oxide signaling on the induction of crassulacean acid metabolism in Guzmania monostachia (Bromeliaceae)

Mioto, Paulo Tamaso
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 02/03/2012 Português
Relevância na Pesquisa
37.44426%
Guzmania monostachia é uma bromélia tanque epífita C3-CAM facultativa, constituindo-se em um modelo muito interessante para estudar a sinalização que ocorre na transição da fotossíntese C3 para CAM. Baseado em resultados obtidos pelo Laboratório de Fisiologia Vegetal do IBUSP, constatou-se que a mudança em questão se dá de forma diferente ao longo do comprimento das folhas dessa espécie, sendo muito mais pronunciada na região apical do que na basal. Outra pesquisa, desenvolvida anteriormente no mesmo laboratório, sugere fortemente que na indução ao CAM, em plantas jovens de abacaxizeiro C3, o óxido nítrico (NO) e o ácido abscísico (ABA) atuam como mediadores dessa resposta. Levando em conta esses fatos, o presente trabalho visou caracterizar a participação do NO e do ABA como sinalizadores do CAM em uma bromélia que é reconhecidamente C3-CAM facultativa na natureza. Além disso, suas folhas apresentam diferentes níveis de expressão do CAM ao longo do comprimento, podendo, assim, constituir-se em um ótimo modelo para estudos de sinalização. Também se buscou, nesta pesquisa,saber se seria possível reduzir o modelo de estudo para folhas destacadas, não necessitando empregar a planta inteira nos experimentais. Após a comparação da fotossíntese entre folhas pertencentes a plantas inteiras e folhas destacadas...

‣ Efeito de uma sobrecarga lipídica sobre o metabolismo energético e hormônios reguladores da fome e saciedade de mulheres pós-menopausadas estratificadas de acordo com o valor do estradiol plasmático; Effect of a lipid overload on energy metabolism and hunger and satiety hormones of postmenopausal women with different plasma estradiol values.

Santos, Roberta de Souza
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 09/10/2012 Português
Relevância na Pesquisa
37.315393%
Climatério é a fase da vida da mulher em que ocorrem alterações hormonais que culminam em alterações metabólicas peculiares desse período, como por exemplo, diminuição do gasto energético e ganho ponderal. Com isso, os objetivos do presente trabalho foram mensurar o gasto energético e calcular a oxidação de carboidratos e lipídios, nos momentos basal e após uma sobrecarga lipídica, de mulheres pós-menopausadas com excesso de peso, estratificadas de acordo com o nível do estradiol plasmático (E2), bem como analisar peptídeos reguladores da fome e da saciedade nos mesmos momentos. Os grupos de mulheres foram: grupo 1- E2 39 pg/mL, 2- 40 E2 59 pg/mL, e 3- E2 60 pg/mL. As voluntárias receberam uma única refeição de 1100 kcal e 72% de lipídios, a qual caracterizou a sobrecarga lipídica. O gasto energético foi medido por calorimetria indireta por um período de cinco horas, sendo que as mensurações foram realizadas nos momentos 30, 60, 90, 150, 210 e 270 minutos. Os peptídeos reguladores da fome e da saciedade foram analisados no momento basal, após 30 e 270 minutos da sobrecarga lipídica. Os grupos foram comparados pelo teste não paramétrico Kruskal-Wallis, e para a comparação entre os momentos no mesmo grupo...

‣ Atividade funcional de polimorfonucleares do sangue de cabritos neonatos, induzida por Escherichia coli e Staphylococcus aureus "in vitro": influência etária e do manejo colostral; Functional activity of polymorphonuclear cells from the blood of goats neonates induced by Escherichia coli and Staphylococcus aureus "in vitro": influence of age and colostrum management.

Cyrillo, Fernanda Cavallini
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 15/03/2011 Português
Relevância na Pesquisa
37.341729%
O objetivo do presente estudo foi avaliar a atividade funcional dos polimorfonucleares (PMNs) do sangue de cabritos neonatos "in vitro" - metabolismo oxidativo e a fagocitose induzidos por S.aureus e E.coli, por meio da citometria de fluxo. Foram utilizados 32 cabritos da raça Saanen, acompanhados quanto ao estado de saúde do nascimento até os 15 dias de idade, distribuídos em quatro grupos: G1- colostro de cabra "in natura"; G2- colostro de cabra aquecido a 56ºC por 60 minutos; G3- colostro de vaca "in natura" e G4 - leite de cabra; sendo avaliados nos seguintes tempos: t0 (antes da ingestão do colostro); t1 (24-48h p.n.); t2 (72-96h p.n); t3 (168-192h p.n) e t4 (336-360h p.n). A avaliação estatística foi realizada pela análise de variância (ANOVA) para a comparação entre os grupos e intragrupos para amostras de pequeno tamanho, de acordo com as variáveis do estudo, com nível de significância de 5%. O metabolismo oxidativo basal não diferiu nos grupos e com a idade. O metabolismo oxidativo aumentou com o estímulo por S. aureus após a ingestão de colostro tratado pelo calor (G2), não apresentando diferenças nos demais grupos. O estímulo com E. coli o aumentou após a ingestão de colostro tratado (G2) e após a ingestão de leite de cabra (G4) a partir de t3...

‣ As equações de predição da taxa metabólica basal são apropriadas para adolescentes com sobrepeso e obesidade?; ¿Las ecuaciones de prediccion de la tasa metabolica basal son apropiadas para adolescentes con sobrepeso y obesidad?; Are basal metabolic rate prediction equations appropriate for overweight and obese adolescents?

Schneider, Patricia; Meyer, Flavia
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
Relevância na Pesquisa
47.09571%
As equações de predição conhecidas podem apresentar valores de taxa metabólica basal (TMB) diferentes daqueles medidos por calorimetria indireta. Os objetivos deste estudo foram descrever a TMB, por meio de calorimetria indireta, em meninos com sobrepeso e obesidade, de 12 a 17 anos de idade, residentes em Porto Alegre, Brasil, e comparar o valor medido com os valores de TMB estimados por equações de predição. A TMB foi medida por calorimetria indireta, pela manhã, em 35 voluntários, sob condições padronizadas de jejum, repouso e ambiente. A média (± desvio-padrão) da TMB medida foi de 1.900,5 ± 248,8kcal em 24 horas. A estimativa da TMB por equações foi significativamente maior, em três das quatro equações (6,5 a 9,5%), do que a TMB medida (p < 0,05). Os dados evidenciaram que as equações de predição não são adequadas para estimar a TMB nos meninos com sobrepeso e obesidade avaliados. O emprego dessas equações, na maioria dos casos, pode superestimar os requerimentos energéticos para meninos com características semelhantes.; Las ecuaciones de predicción conocidas pueden presentar valores de tasa metabólica basal (TMB) diferentes de aquellos medidos por calorimetria indirecta. Los objetivos de este estudio fueron describir la TMB...

‣ Metabolic, ventilatory, and hygric physiology of the gracile mouse opossum (Gracilinanus agilis)

Cooper, C. E.; Withers, P. C.; Cruz-Neto, A. P.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 153-162
Português
Relevância na Pesquisa
37.346538%
We present the first complete study of basic laboratory-measured physiological variables (metabolism, thermoregulation, evaporative water loss, and ventilation) for a South American marsupial, the gracile mouse opossum (Gracilinanus agilis). Body temperature (Tb) was thermolabile below thermoneutrality (Tb = 33.5°C), but a substantial gradient between Tb and ambient temperature (Ta) was sustained even at Ta = 12°C (Tb = 30.6°C). Basal metabolic rate of 1.00 mL O2 g-1 h-1 at Ta = 30°C conformed to the general allometric relationship for marsupials, as did wet thermal conductance (5.7 mL O2 g-1 h-1 °C-1). Respiratory rate, tidal volume, and minute volume at thermoneutrality matched metabolic demand such that O2 extraction was 12.4%, and ventilation increased in proportion to metabolic rate at low T a. Ventilatory accommodation of increased metabolic rate at low Ta was by an increase in respiratory rate rather than by tidal volume or O2 extraction. Evaporative water loss at the lower limit of thermoneutrality conformed to that of other marsupials. Relative water economy was negative at thermoneutrality but positive below Ta = 12°C. Interestingly, the Neotropical gracile mouse opossums have a more positive water economy at low Ta than an Australian arid-zone marsupial...

‣ Energy intake underreporting of adults in a household survey: the impact of using a population specific basal metabolic rate equation

Souza,Danielle Ribeiro de; Anjos,Luiz Antonio; Wahrlich,Vivian; Vasconcellos,Mauricio Teixeira Leite de
Fonte: Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz Publicador: Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2015 Português
Relevância na Pesquisa
46.83863%
The purpose of the present study was to identify energy intake (EI) underreporting and to estimate the impact of using a population specific equation for the basal metabolic rate (BMR) in a probability sample of adults from Niterói, Rio de Janeiro State, Brazil. A sample of 1,726 subjects participated in the study. EI was assessed by a 24-hour dietary recall and EI/BMR was computed with BMR estimated using internationally recommended equations as well as specific equations developed for the adult population of Niterói. Mean EI was 1,570.9 and 2,188.8kcal.day-1 for women and men, respectively. EI decreased with increasing age in both men and women. BMR estimated by the Brazilian equation was significantly lower than the values estimated by the international equation for all age, sex and nutritional status groups. In general, EI underreporting was found in at least 50% of the population, higher in women, and increased with increasing age and body mass index (BMI). The results of the present study confirm that EI is underreported, even when BMR is estimated using population-specific equations.

‣ Effects of hormonal and electrical stimulation of sodium transport on metabolism of toad urinary bladder.

McLaughlin, C W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1984 Português
Relevância na Pesquisa
37.198716%
The carbon dioxide produced by toad urinary bladders bathed on their mucosal surfaces by sodium Ringer solution and on their serosal surfaces by modified Leibovitz tissue culture medium was analysed by multiple regression on both sodium transport and time. The fractions contributed by metabolism related to transport and by basal metabolism were assessed, and the extent to which these might vary with time was determined. This analytical method, which improves the accuracy with which suprabasal metabolism is estimated, was used to examine the effects on metabolism of vasopressin, aldosterone, and mucosa-positive voltage-clamping. Vasopressin (0.05 u./ml), which on average increased sodium transport 2.9 times and concurrently increased the rate of carbon dioxide production in these transporting tissues, also altered the carbon dioxide production of non-transporting, amiloride-treated control hemibladders. For each hemibladder the ratio of sodium transported to suprabasal carbon dioxide produced after vasopressin was compared with that observed before vasopressin. Differences between the ratios were much reduced when the carbon dioxide productions of the paired transporting hemibladders were corrected for the effects of vasopressin on basal carbon dioxide production. With such analysis...

‣ The effect of myoglobin-facilitated oxygen transport on the basal metabolism of papillary muscle.

Loiselle, D S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1987 Português
Relevância na Pesquisa
46.936826%
A mathematical model of oxygen diffusion into cylindrical papillary muscles is presented. The model partitions total oxygen flux into its simple and myoglobin-facilitated components. The model includes variable sigmoidal, exponential, or hyperbolic functions relating oxygen partial pressure to both fractional myoglobin saturation and rate of oxygen consumption. The behavior of the model was explored for a variety of saturation- and consumption-concentration relations. Facilitation of oxygen transport by myoglobin was considerable as indexed both by the elevation of oxygen partial pressure on the longitudinal axis of the muscle and by the fraction of total oxygen flux at the muscle center contributed by oxymyoglobin. Despite its facilitation of oxygen flux at the muscle center, myoglobin made only a negligible contribution to the total oxygen consumption averaged over the muscle cross-section. Hence the presence of myoglobin fails to explain either the experimentally determined basal metabolism-muscle radius relation or the stretch effect observed in isolated papillary muscle.

‣ AN APPARATUS FOR THE STUDY OF RESPIRATORY QUOTIENT AND BASAL METABOLISM OF MICE

Ebeling, Albert H.; Corey, Robert B.
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/01/1930 Português
Relevância na Pesquisa
46.936826%
A simple apparatus has been developed for the study of the respiratory quotient and basal metabolism of mice. Data are given which indicate that the values for the respiratory quotient obtained are accurate to within 0.02. The apparatus is especially designed for rapid, routine manipulation.

‣ Basal Cerebral Metabolism May Modulate the Cognitive Effects of Aβ in Mild Cognitive Impairment: An Example of Brain Reserve

Cohen, Ann D.; Price, Julie C.; Weissfeld, Lisa A.; James, Jeffrey; Rosario, Bedda L.; Bi, Wenzhu; Nebes, Robert D.; Saxton, Judith A.; Snitz, Beth E.; Aizenstein, Howard A.; Wolk, David A.; DeKosky, Steven T.; Mathis, Chester A.; Klunk, William E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 25/11/2009 Português
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37.323428%
Inverse correlations between amyloid-β (Aβ) load measured by Pittsburgh Compound-B (PiB) positron emission tomography (PET) and cerebral metabolism using [18F]fluoro-2-deoxy-D-glucose (FDG) in Alzheimer’s disease (AD) patients, suggest local Aβ-induced metabolic insults. However, this relationship has not been well studied in mild cognitive impairment (MCI) or amyloid-positive controls. Here, we explored associations of Aβ deposition with metabolism via both region-of-interest-based and voxel-based analyses in amyloid-positive control subjects and patients with MCI or AD. Metabolism in parietal and precuneus cortices of AD patients was negatively correlated with PiB retention locally, and more distantly with PiB retention in frontal cortex. In amyloid-positive controls, no clear patterns in correlations were observed. In MCI patients, there were essentially no significant, negative correlations, but there were frequent significant positive correlations between metabolism and PiB retention. Metabolism in anterior cingulate showed positive correlations with PiB in most brain areas in MCI, and metabolism and PiB retention were positively correlated locally in precuneus/parietal cortex. However, there was no significant increase in metabolism in MCI compared to age-matched controls...

‣ The Absence of the Calcium-buffering Protein Calbindin is Associated with Faster Age-related Decline in Hippocampus Metabolism

Moreno, Herman; Burghardt, Nesha S.; Vela-Duarte, Daniel; Masciotti, James; Hua, Fan; Fenton, André A.; Schwaller, Beat; Small, Scott A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.198716%
Although reductions in the expression of the calcium-buffering proteins calbindin D-28K (CB) and parvalbumin (PV) have been observed in the aging brain, it is unknown whether these changes contribute to age-related hippocampal dysfunction. To address this issue, we measured basal hippocampal metabolism and hippocampal structure across the lifespan of C57BL/6J, calbindin D-28k knockout (CBKO) and parvalbumin knockout (PVKO) mice. Basal metabolism was estimated using steady state relative cerebral blood volume (rCBV), which is a variant of fMRI that provides the highest spatial resolution, optimal for the analysis of individual subregions of the hippocampal formation. We found that like primates, normal aging in C57BL/6J mice is characterized by an age-dependent decline in rCBV-estimated dentate gyrus metabolism. Although abnormal hippocampal fMRI signals were observed in CBKO and PVKO mice, only CBKO mice showed accelerated age-dependent decline of rCBV-estimated metabolism in the dentate gyrus. We also found age-independent structural changes in CBKO mice, which included an enlarged hippocampus and neocortex as well as global brain hypertrophy. These metabolic and structural changes in CBKO mice correlated with a deficit in hippocampus-dependent learning in the active place avoidance task. Our results suggest that the decrease in CB that occurs during normal aging is involved in age-related hippocampal metabolic decline. Our findings also illustrate the value of using multiple MRI techniques in transgenic mice to investigate mechanisms involved in the functional and structural changes that occur during aging.

‣ (+)-Z-Bisdehydrodoisynolic Acid Enhances Basal Metabolism and Fatty Acid Oxidation in Female Obese Zucker Rats

Banz, William J.; Strader, April D.; Ajuwon, Kolapo M.; Hou, Yuqing; Meyers, Cal Y.; Davis, Jeremy E.
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.936826%
We have previously reported that the synthetic estrogen, (+)-Z-bisdehydrodoisynolic Acid [(+)-Z-BDDA], attenuated weight gain and cardiovascular risk in obese rodents. To determine if these antiobesity effects were attributed to changes in basal metabolism, we assessed indirect calorimetry and metabolic profile in female obese Zucker (OZR) rats provided (+)-Z-BDDA (0.0002% food admixture) for 11 weeks. Similar to our previous findings, (+)-Z-BDDA reduced weight gain and improved lipid and glucose homeostasis in OZR rats. Furthermore, resting energy expenditure was increased by (+)-Z-BDDA, as evident by heat production and oxygen consumption. We also observed a marked reduction in respiratory quotient (RQ) along with a corresponding induction of hepatic AMPK in rodents provided (+)-Z-BDDA. Collectively, these findings indicate that (+)-Z-BDDA partially attenuated obesity and associated pathologies through increased resting energy expenditure and fatty acid utilization. Further investigation is required to fully elucidate the mechanisms involved as well as to determine the potential therapeutic implications for (+)-Z-BDDA on obesity and its related pathologies.

‣ Oligo-carrageenan kappa increases NADPH, ascorbate and glutathione syntheses and TRR/TRX activities enhancing photosynthesis, basal metabolism, and growth in Eucalyptus trees

González, Alberto; Moenne, Fabiola; Gómez, Melissa; Sáez, Claudio A.; Contreras, Rodrigo A.; Moenne, Alejandra
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 13/10/2014 Português
Relevância na Pesquisa
47.383784%
In order to analyze the effect of OC kappa in redox status, photosynthesis, basal metabolism and growth in Eucalyptus globulus, trees were treated with water (control), with OC kappa at 1 mg mL−1, or treated with inhibitors of NAD(P)H, ascorbate (ASC), and glutathione (GSH) syntheses and thioredoxin reductase (TRR) activity, CHS-828, lycorine, buthionine sulfoximine (BSO), and auranofin, respectively, and with OC kappa, and cultivated for 4 months. Treatment with OC kappa induced an increase in NADPH, ASC, and GSH syntheses, TRR and thioredoxin (TRX) activities, photosynthesis, growth and activities of basal metabolism enzymes such as rubisco, glutamine synthetase (GlnS), adenosine 5′-phosphosulfate reductase (APR), involved in C, N, and S assimilation, respectively, Krebs cycle and purine/pyrimidine synthesis enzymes. Treatment with inhibitors and OC kappa showed that increases in ASC, GSH, and TRR/TRX enhanced NADPH synthesis, increases in NADPH and TRR/TRX enhanced ASC and GSH syntheses, and only the increase in NADPH enhanced TRR/TRX activities. In addition, the increase in NADPH, ASC, GSH, and TRR/TRX enhanced photosynthesis and growth. Moreover, the increase in NADPH, ASC and TRR/TRX enhanced activities of rubisco, Krebs cycle...

‣ Can the basal metabolic rate of endotherms be explained by biophysical modeling? Response to "A new model for the body size-metabolism relationship"

Seymour, R.; White, C.
Fonte: Univ Chicago Press Publicador: Univ Chicago Press
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
47.08465%
The physiological mechanisms that determine basal metabolic rate (BMR) of endotherms have long been debated. This journal has recently presented a new model, based on biophysical principles of heat flux through the tissues of mammals, that attempts to explain the allometric relationship between BMR and body size. We offer a critique of the model and conclude that although the model may describe the physics of heat transfer through the body, it cannot explain mechanistically the level of BMR. BMR determines some of the key variables of the model, but no combination of the variables determines BMR. The model arrives at an equation relating BMR to body mass that is similar to descriptive empirical equations, but this coincidence results from the geometry of the model and the empirical values put into it.; Roger S. Seymour and Craig R. White

‣ Allometric scaling of mammalian metabolism

White, C.; Seymour, R.
Fonte: Company of Biologists Ltd Publicador: Company of Biologists Ltd
Tipo: Artigo de Revista Científica
Publicado em //2005 Português
Relevância na Pesquisa
47.175615%
The importance of size as a determinant of metabolic rate (MR) was first suggested by Sarrus and Rameaux over 160 years ago. Max Rubner's finding of a proportionality between MR and body surface area in dogs (in 1883) was consistent with Sarrus and Rameaux's formulation and suggested a proportionality between MR and body mass (Mb) raised to the power of 2/3. However, interspecific analyses compiled during the first half of the 20th century concluded that mammalian basal MR (BMR, ml O2 h-1) was proportional to Mb3/4, a viewpoint that persisted for seven decades, even leading to its common application to non-mammalian groups. Beginning in 1997, the field was re-invigorated by three new theoretical explanations for 3/4-power BMR scaling. However, the debate over which theory accurately explains 3/4-power scaling may be premature, because some authors maintain that there is insufficient evidence to adopt an exponent of 3/4 over 2/3. If progress toward understanding the non-isometric scaling of BMR is ever to be made, it is first essential to know what the relationship actually is. We re-examine previous investigations of BMR scaling by standardising units and recalculating regression statistics. The proportion of large herbivores in a data set is positively correlated both with the scaling exponent (b...

‣ Lactate metabolism in the isolated perfused rat kidney: relations to renal function and gluconeogenesis.

Cohen, J J; Little, J R
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1976 Português
Relevância na Pesquisa
37.346538%
In the intact dog, decreases in both glomerular filtration rate and net renal Na+ reabsorption due to raised ureteral pressure were not associated with a decrease in renal lactate oxidation rate, although total renal CO2 production decreased in proportion to the changes in net renal reabsorption of Na+ and glomerular filtration rate. 2. In order to determine whether, in the absence of other added substrates, the metabolism of lactate supports only the 'basal' renal metabolism or can enhance renal function as well, the rate of lactate utilization and decarboxylation by the isolated perfused rat kidney have been quantified in relation to renal function and one measure of renal basal metabolism, glucose production. 3. The perfusate was Krebs-Ringer bicarbonate (pH 7-35-7-48) with Fraction V bovine serum albumin, 6g/100 ml. L-(+)-lactate was added to raise the lactate concentration from endogenous levels to 2-5, 5-0 or 10 mM. 4. We determined: net lactate utilization rate, lactate decarboxylation rate (14CO2 produced from L-(+)-[U-14C]lactate), net glucose production rate, and net re-absorptive rate of Na+. 5. The apparent Km and Vmax for lactate oxidation were 2-1 mM and 1-29 mumole.g-1.min-1 respectively. There was no apparent maximum for total lactate utilization rate due to continuing increases in glucose production rate as lactate concentration was raised. At ca. 10 mM lactate...

‣ Validation of predictive equations for basal metabolic rate in eutrophic and obese subjects; Validação de equações de predição da taxa metabólica basal em sujeitos eutróficos e obesos

Krüger, Renata Lopes; Universidade Federal do Rio Grande do Sul; Lopes, André Luiz; Universidade Federal do Rio Grande do Sul. Centro Universitário Univates.; Gross, Júlia da Silveira; Universidade Federal do Rio Grande do Sul.; Macedo, Rodrigo Caudur
Fonte: Universidade Federal de Santa Catarina. Florianópolis, SC. Brasil Publicador: Universidade Federal de Santa Catarina. Florianópolis, SC. Brasil
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; "Avaliado por Pares",; Original paper; Avaliado por Pares; Quase Experimental. Formato: application/pdf
Publicado em 29/12/2014 Português
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DOI: http://dx.doi.org/10.5007/1980-0037.2015v17n1p73 Prediction equations for basal metabolic rate (BMR) continue to be the most common clinical tool for diet prescription; however, the values estimated may differ from those measured by indirect calorimetry (IC), especially in obese subjects. The objective of this study was to determine the BMR of obese and eutrophic subjects by IC, and to compare the results obtained with those estimated by prediction equations in order to identify whether differences exist between predicted values and those measured by IC. Forty men aged 18 to 30 years were evaluated; of these, 20 were grade 1 obese and 20 were eutrophic. The agreement between the prediction equations and IC was evaluated using Bland-Altman (1986) plots. The results showed a variation between the prediction equations and IC of -19.6% to -91% in obese subjects and of 4.2% to 4.4% in eutrophic subjects. In both groups, the Mifflin-St. Jeor equation (1990) was the most accurate, with a difference of -9.1% compared to IC in obese subjects and of 0.9% in eutrophic subjects. This study indicates the Mifflin-St. Jeor equation to be the most adequate to estimate BMR. However, it is important to measure the BMR of obese subjects more accurately and safely in order to establish the best intervention based on physical exercise and healthy eating.; DOI: http://dx.doi.org/10.5007/1980-0037.2015v17n1p73 Equações de predição para taxa metabólica basal (TMB) são amplamente utilizadas para prescrição dietética...

‣ Energy intake underreporting of adults in a household survey: the impact of using a population specific basal metabolic rate equation

Souza,Danielle Ribeiro de; Anjos,Luiz Antonio; Wahrlich,Vivian; Vasconcellos,Mauricio Teixeira Leite de
Fonte: Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz Publicador: Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2015 Português
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The purpose of the present study was to identify energy intake (EI) underreporting and to estimate the impact of using a population specific equation for the basal metabolic rate (BMR) in a probability sample of adults from Niterói, Rio de Janeiro State, Brazil. A sample of 1,726 subjects participated in the study. EI was assessed by a 24-hour dietary recall and EI/BMR was computed with BMR estimated using internationally recommended equations as well as specific equations developed for the adult population of Niterói. Mean EI was 1,570.9 and 2,188.8kcal.day-1 for women and men, respectively. EI decreased with increasing age in both men and women. BMR estimated by the Brazilian equation was significantly lower than the values estimated by the international equation for all age, sex and nutritional status groups. In general, EI underreporting was found in at least 50% of the population, higher in women, and increased with increasing age and body mass index (BMI). The results of the present study confirm that EI is underreported, even when BMR is estimated using population-specific equations.