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1.
Sci Total Environ ; 895: 164908, 2023 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-37385497

RESUMO

Deltas are the locus of river-borne sediment accumulation, however, their role in sequestering plastic pollutants is still overlooked. By combining geomorphological, sedimentological, and geochemical analyses, which include time-lapse multibeam bathymetry, sediment provenance, and µFT-IR analyses, we investigate the fate of plastic particles after a river flood event providing an unprecedented documentation of the spatial distribution of sediment as well as of microplastics (MPs), including particles fibers, and phthalates (PAEs) abundances in the subaqueous delta. Overall sediments are characterized by an average of 139.7 ± 80 MPs/kg d.w., but display spatial heterogeneity of sediment and MPs accumulation: MPs are absent within the active sandy delta lobe, reflecting dilution by clastic sediment (ca. 1.3 Mm3) and sediment bypass. The highest MP concentration (625 MPs/kg d.w.) occurs in the distal reaches of the active lobe where flow energy dissipates. In addition to MPs, cellulosic fibers are relevant (of up to 3800 fibers/kg d.w.) in all the analyzed sediment samples, and dominate (94 %) with respect to synthetic polymers. Statistically significant differences in the relative concentration of fiber fragments ≤0.5 mm in size were highlighted between the active delta lobe and the migrating bedforms in the prodelta. Fibers were found to slightly follow a power law size distribution coherent with a one-dimensional fragmentation model and thus indicating the absence of a size dependent selection mechanism during burial. Multivariate statistical analysis suggests traveling distance and bottom-transport regime as the most relevant factors controlling particle distribution. Our findings suggest that subaqueous prodelta should be considered hot spots for the accumulation of MPs and associated pollutants, albeit the strong lateral heterogeneity in their abundances reflects changes in the relative influence of fluvial and marine processes.

2.
Rev Med Suisse ; 4(160): 1383-6, 2008 Jun 04.
Artigo em Francês | MEDLINE | ID: mdl-18630060

RESUMO

Cardiovascular disease is the main cause of mortality in diabetic patients. The risk of cardiovascular disease occurs at a lower glycemic level compared to microvascular complications. Post-prandial hyperglycemia seems to play a major role in the development of atherosclerotic lesions. In this article we review the evidence regarding the prognostic value of post-challenge hyperglycaemia relative to the risk of cardiovascular disease, explore the physio-pathologic mechanisms responsible for the negative effects of post-prandial hyperglycaemia and detail the benefits of treatment aimed at controlling post-prandial glycaemia.


Assuntos
Doenças Cardiovasculares/fisiopatologia , Diabetes Mellitus Tipo 2/fisiopatologia , Hiperglicemia/fisiopatologia , Diabetes Mellitus Tipo 2/tratamento farmacológico , Humanos , Período Pós-Prandial , Prognóstico
3.
Rev Med Suisse ; 3(114): 1437-8, 1440-1, 2007 Jun 06.
Artigo em Francês | MEDLINE | ID: mdl-17639664

RESUMO

Most studies, which are retrospective, show contradictory results regarding the incidence of road traffic accident among diabetic patients. The most frequent cause of accident is hypoglycemia. One should also consider impaired vision (retinopathy, maculopathy), neuropathy (feet insensitivity) and sleep apnoea in overweight patients. Hypoglycemia not only leads to impaired judgement during driving, but also to a reduction in performances, frequent hypoglycemias impair symptom recognition and increase the risk of loss of consciousness. Patients should benefit from teaching about hypoglycemia, i.e. how to recognize and correct it in order to avoid accidents. Generally they should not drive if their glycemia is under 5 mmol/l without correcting it with an adequate amount of carbohydrates.


Assuntos
Condução de Veículo , Complicações do Diabetes/psicologia , Hipoglicemia/psicologia , Condução de Veículo/legislação & jurisprudência , Humanos , Hipoglicemia/diagnóstico , Julgamento
4.
Clin Nutr ; 25(2): 311-8, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16697084

RESUMO

These guidelines are intended to give evidence-based recommendations for the use of enteral nutrition (EN) in patients with chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD). They were developed by an interdisciplinary expert group in accordance with officially accepted standards and are based on all relevant publications since 1985. They have been discussed and accepted in a consensus conference. EN by means of oral nutritional supplements (ONS) or tube feeding (TF) enables nutritional intake to be maintained or increased when normal oral intake is inadequate. No data are yet available concerning the effects of EN on cachexia in CHF patients. However, EN is recommended to stop or reverse weight loss on the basis of physiological plausibility. In COPD patients, EN in combination with exercise and anabolic pharmacotherapy has the potential to improve nutritional status and function. Frequent small amounts of ONS are preferred in order to avoid postprandial dyspnoea and satiety as well as to improve compliance.


Assuntos
Cardiologia/normas , Nutrição Enteral/normas , Padrões de Prática Médica , Pneumologia/normas , Europa (Continente) , Insuficiência Cardíaca/terapia , Humanos , Doença Pulmonar Obstrutiva Crônica/terapia
5.
Nutrition ; 20(6): 528-35, 2004 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15165615

RESUMO

OBJECTIVE: Important changes in administering total parenteral nutrition (PN) admixtures have occurred over the past decade. This study describes hospital pharmacists' practices in France (F), Switzerland (CH), and Belgium (B). METHODS: From the responses received using a standardized questionnaire, (n = 378) we determined the origin, types of container used, and choice of PN formula (standard versus tailor-made) and the type of quality control and the existence of nutrition support teams. RESULTS: The mean response rates were 55.6% (CH), 30.5% (F), and 24.5% (B). Standard formulas were used mainly for adult patients (CH, 86%; F, 79%; B, 86%), whereas approximately 50% of tailor-made PN bags were used for children. Single-compartment or multicompartment bags or glass bottles contained standard formulas. Most standard formulas were provided by industry, apart from (B), where 50% of PN solutions were compounded by hospital pharmacies. Single-compartment bags contained generally tailor-made formulas produced exclusively by hospital pharmacies in (CH) and (B), whereas 33% were provided by industry in (F). Quality controls were mostly visual and occurred in 75% to 95% of hospitals. Nutrition support teams were present in 32% to 45% of hospitals. CONCLUSION: The choice, origin, and type of container used for PN formulas were highly variable among countries. However, the use of standard formulas in bags was predominant in (CH) and (B). The function of nutrition support teams was similar in (F), (CH), and (B).


Assuntos
Nutrição Parenteral/métodos , Nutrição Parenteral/estatística & dados numéricos , Serviço de Farmácia Hospitalar/estatística & dados numéricos , Padrões de Prática Médica/estatística & dados numéricos , Bélgica , Estudos Transversais , Embalagem de Medicamentos/estatística & dados numéricos , França , Humanos , Serviço de Farmácia Hospitalar/normas , Controle de Qualidade , Inquéritos e Questionários , Suíça
6.
Transplant Proc ; 36(2): 316-8, 2004 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15050144

RESUMO

Two 13-year-old monozygotic twins were used for living related small bowel transplantation (SBTx). The recipient presented with short gut syndrome secondary to complicated abdominal surgery. The indication for SBTx was based on a failure to thrive and a poor tolerance of TPN. The donor was an identical twin, as demonstrated by skin graft acceptance, which allowed performance of SBTx without immunosuppression. Growth charts were used to follow intestinal absorption functions and body composition. The donor was used as a control for the recipient. The recipient, who was transplanted with 160 cm of donor ileum, was discharged on postoperative day 62 on a regular diet. Before SBTx the recipient was 10 kg lighter in body weight than the donor, a gap that was progressively reduced over the follow-up period. A height deficit of 3 cm reversed within 1 year after SBTx. A 10-kg deficit in fat-free body mass was completely extinguished within 18 months. By 18 months posttransplant, recipient serum albumin and prealbumin were normal and comparable to donor values. d-Xylose absorption in the recipient remained lower than that in the donor. Within 6 months fecal fat excretion normalized in the recipient. d-Xylose absorption and fecal fat excretion were always within a normal range in the donor.


Assuntos
Intestino Delgado/transplante , Adolescente , Composição Corporal , Insuficiência de Crescimento/cirurgia , Crescimento , Humanos , Recém-Nascido , Absorção Intestinal , Doadores Vivos , Masculino , Transplante de Pele , Fatores de Tempo , Resultado do Tratamento , Gêmeos Monozigóticos
7.
Acta Diabetol ; 40 Suppl 1: S165-7, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14618462

RESUMO

Malnutrition occurs frequently prior to lung transplantation (LTR), but patients gain weight after LTR. The study aimed to determine the ratio changes of fat-free mass (deltaFFM): changes of body weight (deltaBW) during refeeding. A total of 37 LTR patients were measured for weight and FFM and body fat by bioimpedance analysis at 1 month post-LTR, then annually for 3 years. Linear regressions determined the ratio deltaFFM:deltaBW during refeeding. DeltaFFM was: year- 1=1.822+0.389* deltaBW, r(2)=0.397; yr-2=0.611+0.246* deltaBW, r(2)=0.441; yr-3=-0.17+0.208 * deltaBW, r(2)=0.319. Refeeding during year-1 in thin subjects resulted in a ratio deltaFFM:deltaBW of 0.389, whereas the change in ratio deltaFFM:deltaBW during year- 2 and 3 was 0.246 and 0.208, respectively. Refeeding resulted in a larger ratio deltaFFM:deltaBW in thin subjects versus normal and overweight subjects. Thus, refeeding in underweight LTR patients is geared to normalizing depleted FFM, whereas later FFM gains were similar to FFM gains in normal and overweight subjects.


Assuntos
Tecido Adiposo/anatomia & histologia , Índice de Massa Corporal , Peso Corporal/fisiologia , Transplante de Pulmão/fisiologia , Fenômenos Fisiológicos da Nutrição , Aumento de Peso/fisiologia , Humanos , Análise de Regressão , Fatores de Tempo
8.
Acta Diabetol ; 40 Suppl 1: S258-60, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14618487

RESUMO

The aim of this study was to determine the prevalence of low fat-free mass index (FFMI) and high and very high body fat mass index (BFMI) after lung transplantation (LTR). A total of 37 LTR patients were assessed prior to and at 1 month, 1 year and 2 years for FFM and compared to 37 matched volunteers (VOL). FFM was calculated by the Geneva equation and normalized for height (kg/m(2)). Subjects were classified as FFMI "low", 8.2 kg/m(2) in men and >11.8 kg/m(2) in women. In 23 M/14 F, body mass index (BMI) was 22.3+/-4.4 and 20.1+/-4.9 kg/m(2), respectively. The prevalence of low FFMI was 80% at 1 month and 33% at 2 years after LTR. Prevalence of very high BFMI increased and was higher in patients than VOL after LTR. The prevalence of low FFMI was high prior to and remained important 2 years after LTR, whereas BFMI was lower prior to and higher 2 years after LTR.


Assuntos
Tecido Adiposo/anatomia & histologia , Índice de Massa Corporal , Transplante de Pulmão/fisiologia , Composição Corporal , Feminino , Seguimentos , Humanos , Masculino , Avaliação Nutricional , Período Pós-Operatório , Prevalência , Valores de Referência , Fatores de Tempo
9.
Clin Nutr ; 22(2): 115-23, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12706127

RESUMO

BACKGROUND & AIMS: This study aimed to assess the ability of the hospital meal service to meet patients' nutritional needs. METHODS: All hospitalised patients who received 3 meals/day without artificial nutritional support were included. The nutritional values of food served, consumed and wasted during a 24 h period were compared to patients' needs estimated as energy: 110% Harris-Benedict formula; protein: 1.2 or 1.0 g/kg bodyweight/day for patients < or = or > 65 years old, respectively. A structured interview recorded patients' evaluation of the meal quality, their reasons for non-consumption of food and the relationship between food intake and disease. RESULTS: Out of 1707 patients included, 1416 were fully assessable (59% women; 68+/-21 years; body mass index: 24.3+/-5.1 kg/m(2)). Daily meals provided 2007+/-479 kcal and 78+/-21 g of protein and exceeded patients' needs by 41% and 15%, respectively. However, 975 patients did not eat enough. Plate waste was 471+/-372 kcal and 21+/-17 g of protein/day/patient. Moreover, the food intake of 572 (59%) of these underfed patients was not predominantly affected by disease. Logistic regression analyses identified as other risk factors: elevated BMI, male gender, modified diet prescription, length of stay <8 or > or = 90 days and inadequate supper. CONCLUSION: Despite sufficient food provision, most of the hospitalised patients did not cover their estimated needs. Since insufficient food intake was often attributed to causes other than disease, there should be potential to improve the hospital meal service.


Assuntos
Ingestão de Alimentos , Serviço Hospitalar de Nutrição/normas , Distúrbios Nutricionais , Necessidades Nutricionais , Idoso , Inquéritos sobre Dietas , Feminino , Análise de Alimentos , Preferências Alimentares , Hospitalização , Humanos , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Distúrbios Nutricionais/epidemiologia , Distúrbios Nutricionais/etiologia , Distúrbios Nutricionais/prevenção & controle , Estudos Prospectivos , Fatores de Risco , Fatores Sexuais , Gerenciamento de Resíduos
10.
Gut ; 52(5): 659-62, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12692049

RESUMO

While small bowel transplantation (SBTX) may allow parenteral nutrition independence in the case of short bowel syndrome, its effects on body composition and growth are unclear. For the first time, a paediatric living related SBTX was performed between monozygotic twins. This case report describes their four year nutritional follow up. The 13 year old recipient and his healthy brother underwent measurements of body composition by 50 kHz bioimpedance analysis and bone mineral density of the femoral neck and total femur by dual energy x ray absorptiometry. Xylose tests and measurements of faecal fat evaluated gut absorption. All tests were performed before and after SBTX. Body weight increased from 34.7 to 51.9 kg in the recipient and from 45.0 to 53.2 kg in the donor within four years. The recipient caught up with the height and fat free mass of his brother within two years. Fat mass, and total femur and femoral neck densities are still lower in the recipient than in the donor four years after SBTX (-1.2 kg, -0.087 g/cm(2), -0.035 g/cm(2)). The xylose test of the recipient was still abnormally low after four years (1.37 mmol/l) and faecal fat was high until two years after SBTX (March 2001: 12 g/24 h). The donor always showed normal xylose tests and faecal fat, except for one episode of high faecal fatty acids about 10 months after SBTX. SBTX improved the nutritional state and growth of the graft recipient although body composition, femoral bone mineral densities, and intestinal absorption had not completely normalised after four years.


Assuntos
Intestino Delgado/transplante , Estado Nutricional/fisiologia , Gêmeos Monozigóticos , Adolescente , Composição Corporal/fisiologia , Estatura/fisiologia , Densidade Óssea/fisiologia , Calorimetria , Metabolismo Energético/fisiologia , Seguimentos , Humanos , Absorção Intestinal/fisiologia , Masculino , Minerais/sangue , Nutrição Parenteral/métodos , Vitaminas/sangue , Aumento de Peso/fisiologia
11.
Clin Nutr ; 21(6): 487-90, 2002 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12468368

RESUMO

BACKGROUND AND AIMS: Radiation injury to the gut induces nutrient losses that compromise the body ability to adequately fight infection, heal wounds and recover from illness. Recombinant growth hormone (rhGH), is known to enhance anabolism, therefore, we tested the hypothesis that rhGH preserves whole body growth and trophism of the jejunum and ileum of irradiated rats. METHODS: After acclimatization period, the rats were divided in three groups: (1). control rats (C), (2). rats irradiated with a single dose of 10 Gy (group A); (3). rats irradiated with a single dose of 5 Gy (Group B); after irradiation, rats were given subcutaneously (sc) saline or 0.25 or 0.50 mg rhGH/kg BW/d for the following 6 days. Body weight changes were recorded during this time. On day 6 post-radiation, rats were killed and small intestine mucosa dry and wet weights were measured, as well as mucosa protein content. RESULTS: Group A rats lost body weight during the 6-day post-radiation period, regardless of rhGH treatment and dosage. rhGH was effective in preventing weight loss and normalizing growth in group B rats (saline 23.1+/-11.1, vs. controls P<0.05; rhGH: 35.0+/-10.0 g BW/d, vs. controls P = ns). Trophic effect of rhGH was observed on mucosa weight and mucosa protein content in rats irradiated with 5 Gy, but not in those receiving 10 Gy. CONCLUSION: rhGH seems to normalize growth and mucosa protein content in irradiated rats. However, rhGH beneficial effects were observed only in rats receiving the lower dose of radiation.


Assuntos
Hormônio do Crescimento/administração & dosagem , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/efeitos da radiação , Lesões Experimentais por Radiação/prevenção & controle , Animais , Peso Corporal/efeitos dos fármacos , Peso Corporal/efeitos da radiação , Modelos Animais de Doenças , Relação Dose-Resposta à Radiação , Hormônio do Crescimento/uso terapêutico , Mucosa Intestinal/patologia , Intestino Delgado/efeitos dos fármacos , Intestino Delgado/patologia , Intestino Delgado/efeitos da radiação , Masculino , Tamanho do Órgão/efeitos dos fármacos , Tamanho do Órgão/efeitos da radiação , Ratos , Ratos Wistar
12.
Rev Med Suisse Romande ; 121(9): 635-40, 2001 Sep.
Artigo em Francês | MEDLINE | ID: mdl-11723703

RESUMO

The HIV infection leads to many nutritional problems. For a long time, the Wasting Syndrome was one of the most frequent inaugural features of AIDS and still concerns many patients. The weight loss worsens the prognosis of the disease. The reduced dietary intakes, the increased digestive losses and energetic expenditure result in severe malnutrition. Therefore, the nutritional support and its association with orexigenes, anabolic agents and physical activity has to be carefully selected. The adverse events of new antiretroviral drugs influence the nutritional state and the patient's compliance towards their treatments. For lipodystrophy, whose etiology is still unknown, no treatment has yet been found. Metabolic disorders (dyslipidemia, glucose intolerance, diabetes, etc.) in this presently chronic disease require particular attention since they increase cardiovascular risks. In general they are sensitive to a dietary approach.


Assuntos
Infecções por HIV/complicações , Distúrbios Nutricionais/etiologia , Humanos , Distúrbios Nutricionais/terapia
13.
Curr Opin Clin Nutr Metab Care ; 4(4): 313-20, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11458027

RESUMO

In the effort to improve the long-term outcome in critically ill patients, the utilization of anabolic agents, such as human recombinant growth hormone, has been proposed in order to reduce catabolism and improve nutritional status. A recent multicentre study regarding the use of human recombinant growth hormone in intensive care unit patients showed an unexpected increase in the mortality rate in human recombinant growth hormone-treated patients. This finding is in contrast with previous literature data reporting either no differences or an even lower mortality rate with the administration of human recombinant growth hormone. This review evaluates the possible reasons for this dramatic difference in outcomes between the multicentre study and the existing literature. Articles dealing with human recombinant growth hormone administration either in intensive care unit patients (n=26) or in postoperative patients (n=16) have been reviewed. Our analysis suggests that the low caloric intake given to patients enrolled in the multicentre study might have been inadequate to compensate for the hypermetabolism of these patients, and could not support the prolonged and delayed administration of high doses of human recombinant growth hormone. Whether the beneficial metabolic effects of human recombinant growth hormone translate into better clinical outcomes deserves further investigation. In addition, the careful selection of patients to be treated, and close monitoring of both the adequacy of caloric support and modality of human recombinant growth hormone administration would favour the safety of human recombinant growth hormone utilization in critical care settings.


Assuntos
Estado Terminal/terapia , Metabolismo Energético , Hormônio do Crescimento/uso terapêutico , Estresse Fisiológico/metabolismo , Estado Terminal/mortalidade , Humanos , Necessidades Nutricionais , Estado Nutricional , Estresse Fisiológico/prevenção & controle , Resultado do Tratamento
14.
J Nutr ; 130(4): 761-6, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10736327

RESUMO

The quantitative relationships between nitrogen (N) intake, urea production, excretion and amino acid oxidation are currently a matter of debate. Some investigators have proposed that urea production is essentially constant over a wide range of N intakes and that urea hydrolysis is regulated according to the N needs of the organism. We have assessed this proposal by compiling results from four separate experiments in healthy young adults (n = 34) carried out in our laboratories and all at the end of the respective diet periods using an identical 24-h continuous intravenous infusion of [(15)N, (15)N]urea and L-[1-(13)C]leucine. The N intakes were: expt. 1; protein-free diet for 5 d; expt. 2; N at 44 mg N. kg(-1). d(-1) from a balanced L-amino acid mixture for 13 d; expt. 3; N at 161 mg. kg(-1). d(-1) from egg protein for 6 d; expt. 4 -one group received 157 mg. kg(-1). d(-1) and the other 392 mg. kg(-1). d(-1) from milk-protein-based diets for 6 d. Urea production and excretion were linearly correlated with N intake (r = 0.98 and 0.94, respectively; P < 0.01). Urea hydrolysis increased linearly with N intake (r = 0.7; P < 0.05), with considerable variation in the rate among individuals, especially at the N intake of approximately 160 mg N. kg(-1)d(-1). These findings are consistent with the generally accepted view that a control of body N balance is via a regulation of urea production. They do not support the concept that urea hydrolysis is the more important site in the control of body N loss.


Assuntos
Proteínas Alimentares/administração & dosagem , Leucina/metabolismo , Ureia/metabolismo , Adulto , Dieta , Proteínas Alimentares/farmacologia , Relação Dose-Resposta a Droga , Feminino , Humanos , Hidrólise , Masculino , Nitrogênio/administração & dosagem , Oxirredução , Valores de Referência
15.
Metabolism ; 49(1): 122-8, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10647075

RESUMO

To determine whether trained individuals rely more on fat than untrained persons during high-intensity exercise, six endurance-trained men and six untrained men were studied during 30 minutes of exercise at 75% to 80% maximal oxygen consumption (VO2max). The rates of appearance (Ra) and disappearance (Rd) of glycerol and free fatty acids (FFAs) were determined using [1,1,2,3,3-2H]glycerol and [1-13C]palmitate, respectively, whereas the overall rate of fatty acid oxidation was determined using indirect calorimetry. During exercise, the whole-body rate of lipolysis (ie, glycerol Ra) was higher in the trained group (7.1 +/- 1.2 v 4.5 +/- 0.7 micromol x min(-1) x kg(-1), P < .05), as was the Ra (approximately Rd) of FFA (9.0 +/- 0.9 v 5.0 +/- 1.0 micromol x min(-1) x kg(-1), P < .001). FFA utilization was higher in trained subjects even when expressed as a percentage of total energy expenditure (10% +/- 1% v 7% +/- 1%, P < .05). However, this difference in plasma FFA flux could not account for all of the difference in fatty acid oxidation between trained and untrained subjects (20.8 +/- 3.3 v 7.9 +/- 1.6 micromol x min(-1) x kg(-1), or 23% +/- 3% v 13% +/- 2% of total energy expenditure, both P < .05). Thus, the oxidation of fatty acids derived from some other source also must have been greater in the trained men. We conclude that trained athletes use more fat than untrained individuals even during intense exercise performed at the same percentage of VO2max. The additional fatty acids appear to be derived from both adipose tissue and, presumably, intramuscular triglyceride stores.


Assuntos
Metabolismo dos Lipídeos , Resistência Física/fisiologia , Adulto , Calorimetria , Epinefrina/sangue , Ergometria , Ácidos Graxos não Esterificados/sangue , Glicerol/sangue , Humanos , Insulina/sangue , Ácido Láctico/sangue , Lipólise , Masculino , Norepinefrina/sangue , Respiração
16.
Am J Clin Nutr ; 71(2): 491-9, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10648263

RESUMO

BACKGROUND: We previously studied methionine kinetics and oxidation with the tracer L-[1-(13)C, methyl-(2)H(3)]methionine. OBJECTIVES: We sought to explore methionine-cysteine interrelations in adults by using L-[1-(13)C]cysteine under different dietary conditions. DESIGN: In experiment 1, 12 adults consumed a protein-free diet for 6 d. On day 7, methionine (n = 6) or cysteine (n = 6) oxidation rates were measured during an 8-h continuous infusion of L-[1-(13)C, methyl-(2)H(3)]methionine or L-[1-(13)C]cysteine, respectively. In experiment 2, 6 young men consumed 3 diets for 6 d each before a tracer study on day 7 with L-[1-(13)C]cysteine. The amounts (in mg*kg(-)(1)*d(-)(1)) of methionine and cysteine, respectively, were: high-methionine (HM) diet, 13 and 0; low-methionine (LM) diet, 6.5 and 0; and methionine-plus-cystine (MC) diet, 6.5 and 5.6. Cysteine flux and oxidation rates were determined and sulfur amino acid (SAA, methionine plus cysteine) balances were estimated. RESULTS: In experiment 1, rates of methionine and cysteine oxidation were similar to losses predicted from obligatory nitrogen losses. In experiment 2, SAA balance was less negative when subjects consumed the HM diet than the LM and MC diets (interaction, P = 0.034), largely because of a difference in fed-state balance (HM compared with LM, P < 0.01; HM compared with MC, P < 0.05). There was no evidence of a sparing effect of dietary cystine on the methionine requirement. CONCLUSION: These studies support use of [1-(13)C]cysteine for studying whole-body SAA oxidation and conclusions that maintenance of SAA balance is best achieved by supplying methionine at approximately the FAO/WHO/UNU recommendations for total SAA intake (13 mg*kg(-)(1)*d(-)(1)).


Assuntos
Cisteína/metabolismo , Cistina/farmacocinética , Metionina/farmacocinética , Adulto , Testes Respiratórios , Dióxido de Carbono/análise , Radioisótopos de Carbono , Cisteína/sangue , Cistina/administração & dosagem , Dieta com Restrição de Proteínas , Jejum , Feminino , Humanos , Infusões Intravenosas , Masculino , Metionina/administração & dosagem , Metionina/sangue , Necessidades Nutricionais , Oxirredução , Trítio
17.
Curr Opin Gastroenterol ; 16(2): 160-5, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17024035

RESUMO

The discovery of leptin in 1990 was the culmination of earlier work which recognized that communication between the adipocyte and the hypothalamus was important in maintaining body weight. Leptin, which is a 16 kilodalton protein-encoded by the OB gene, is involved in the regulation of food intake, body composition, and energy expenditure through a central feedback mechanism. Initially thought to be adipocyte-specific, the OB gene, as well as the leptin receptor, have been found in a variety of other tissues. Relevant to this review, the leptin gene and its receptor have been identified in the stomach, intestine, liver, and pancreas. Recent data also suggest that leptin may act locally within the gastrointestinal tract to influence intestinal function. This review emphasizes the concept that leptin may be a new gastrointestinal hormone and the need to expand the focus of leptin research to include all phases of weight maintenance, such as nutrient absorption and utilization, in addition to food intake.

18.
Metabolism ; 48(11): 1378-86, 1999 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-10582545

RESUMO

In a recent study, we observed that the 24-hour leucine oxidation measured when three equal meals providing a generous intake of leucine (approximately 90 mg x kg(-1) x d(-1)) are eaten during the day is 16% lower (P < .01) than that for the same diet given as 10 hourly, equal meals. We hypothesized that the pattern of meal intake at a lower level of dietary leucine would affect the 24-hour rate of leucine oxidation and possibly improve the retention of dietary leucine. A total of 11 healthy adults participated in this investigation. The daily leucine intake was 182 micromol x kg(-1) x d(-1) (38 mg x kg(-1) x d(-1)) given with an L-amino acid diet. All subjects received three discrete meals daily for 6 days prior to a 24-hour intravenous (IV) tracer infusion of L-[1-13C]-leucine on day 7 (study 1). Four of these subjects participated in two additional studies of similar design. Study 2 involved giving [1-13C]-leucine as a constant IV infusion together with tracer added to the amino acid mixture at each meal time. In study 3, subjects received the three meals with added [1-13C]-leucine tracer while [2H3]-leucine was given as a constant IV infusion. Total leucine oxidation in studies 1 and 2 was 238+/-66 and 231+/-85 micromol x kg(-1) x d(-1), respectively. Leucine balance was positive, amounting to 18% of the total (diet + tracer) intake. The estimated mean nitrogen balance was +8 mg x kg(-1) x d(-1). Leucine oxidation was higher (P < .01) for breakfast than for the lunch meal. This difference was associated with lower insulin and higher plasma leucine concentrations at breakfast versus lunch periods. The results from study 3 suggest that the higher rate of leucine oxidation observed at breakfast as compared with lunch is not due to a difference in the immediate splanchnic fate of absorbed leucine from each meal. In comparison to our previous small frequent-meal studies, the pattern of meal feeding influences overall leucine utilization at both generous and limiting leucine intakes. Hence, it is possible that the pattern of meal feeding may affect estimations of amino acid requirements using the tracer-balance approach. Longer-term dietary studies will be needed to establish whether and the extent to which this is so.


Assuntos
Ingestão de Alimentos , Leucina/farmacocinética , Adulto , Aminoácidos/farmacocinética , Isótopos de Carbono , Ingestão de Energia , Humanos , Leucina/administração & dosagem , Leucina/metabolismo , Oxirredução , Valores de Referência , Fatores de Tempo
19.
Am J Clin Nutr ; 70(4): 474-83, 1999 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-10500015

RESUMO

BACKGROUND: Estimation of the minimum requirement for indispensable amino acids (IAAs) has been attempted by assuming that obligatory oxidative losses (OOLs) of IAAs can be approximated from nitrogen losses and that the efficiency of utilization of IAAs at requirement intakes is approximately 70%. OBJECTIVE: We wished to determine the rates of OOLs in healthy adults, using L-[1-(13)C]leucine and L-[1-(13)C, methyl-(2)H(3)]methio-nine as tracers, after adjustment to a protein-free diet and how these rates compare with those when either sulfur amino acids (SAAs: methionine and cyst(e)ine) or leucine were removed from an otherwise adequate diet. DESIGN: Eleven subjects were randomly assigned to a 5-d protein-free diet or a 5-d diet providing adequate nitrogen and amino acids except for the SAAs or leucine. A 24-h constant intravenous infusion of [(15)N, (15)N]urea and L-[1-(13)C]leucine (Leu group; n = 5) or L-[1-(13)C, methyl-(2)H(3)]methionine (Met group; n = 6 ) began at 1800 on day 5 and rates of amino acid oxidation were determined. RESULTS: Mean (+/-SD) oxidation rates (mg kg(-)(1) d(-)(1)) of methionine and leucine were 6.4 +/- 1.4 and 24.7 +/- 3.6, respectively, with the protein-free diet; rates were significantly lower (3.9 +/- 2.2 and 7. 2 +/- 3.4, respectively) after the SAA- and leucine-free diets. Urea production was significantly lower (P < 0.01) with the protein-free than with the SAA- or leucine-free diet. CONCLUSIONS: Isotopically determined OOLs for methionine and leucine are consistent with losses predicted from nitrogen excretion, and consistent with our previous measurements of cysteine oxidation as an index of total SAA losses. The data further support our earlier conclusions regarding methionine sparing by cysteine and tentative recommended SAA requirements in adults.


Assuntos
Aminoácidos Essenciais/metabolismo , Leucina/metabolismo , Metionina/metabolismo , Adulto , Dióxido de Carbono/análise , Dióxido de Carbono/sangue , Isótopos de Carbono , Deutério , Dieta com Restrição de Proteínas , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Cetoácidos/sangue , Leucina/sangue , Metionina/sangue , Isótopos de Nitrogênio , Oxirredução , Ureia/sangue , Ureia/urina
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