ISSN:1363-1950    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1363-1950    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Purpose of reviewTo understand the principles of systematic reviewing and meta-analysis, using recent examples from the medical literature to highlight some of these points.Recent findingsThe word ‘meta-analysis’ is an intimidating one, and its associated jargon makes it seem incomprehensible. Actually, it is only a mathematical maneuver to add up data in a systematic review; it might be better called ‘meta-addition’. The systematic review is a process of using the best available evidence to answer a particular clinical question. Data combination (usually done with meta-analysis) increases the power to see small differences and makes a more precise estimate of a treatment effect. Its major drawback is heterogeneity (the proverbial problem of adding apples and oranges). Systematic reviews have been used by medical societies to create position statements. Such statements have suggested that parenteral nutrition is far less efficacious than previously believed. Systematic reviews in some areas of nutritional support have clarified type II errors. Problems exist, however, in a number of the published meta-analyses of aspects of this therapy.SummaryEspecially in an era of resource restraint, we need to become more skilled at interpreting evidence from clinical research.

ISSN:1363-1950    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Purpose of reviewThis review discusses diverse methods that have been used in several recent papers for the qualitative and quantitative analysis of lipids, studies of lipid oxidation, lipoprotein fractionation, and studies of lipid metabolism and metabolic kinetics using tracers. Papers for this review were selected on the basis of their timeliness, novelty, and/or their potential impact on diverse fields of lipid metabolism.Recent findingsMany methods used for studies of lipid metabolism employ advanced chromatographic and mass spectrometric techniques to characterize lipids. In particular, the use of stable isotopically labeled tracers has become increasingly important to study metabolic kinetics.SummarySuch developments in methodology will continue to advance studies of lipid metabolism in many areas of clinical interest, including heart disease, obesity, and diabetes.

ISSN:1363-1950    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Purpose of reviewIn this review methods to measure the content and distribution of body fat or adipose tissue in humans are examined. The review particularly emphasizes methods to characterize regional fat distribution and ectopic fat (fat contained within other tissues) including specific applications and implications of region-specific or tissue-specific fat content.Recent findingsRecent novel applications of body composition methods, including in-vivo imaging modalities, magnetic resonance spectroscopy techniques, and direct measurement of extracted tissue have advanced our understanding of many health related issues including obesity, type 2 diabetes mellitus, progressive muscle weakness in aging and lipodystrophy. In particular, the accumulation of lipid within muscle and liver has received increased attention because of its association with metabolic dysregulation or impaired muscle function.SummaryMethods to quantify total body fat content in humans have provided considerable insight into obesity and related disorders, the aging process and its associated changes in function, and response to intervention. However, these methods have typically not been able to identify fat contained within specific regions of the body or within specific tissue. Direct quantification of fat distribution and fat within tissue in humans have been accomplished through in-vivo imaging techniques as well as invasive histological and biochemical approaches, and have advanced our understanding of many structure-function relationships. Further queries about human health and disease will undoubtedly lead to refinement of these methods and innovation of new body composition methodologies.

ISSN:1363-1950    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Purpose of reviewThis is a review of recent studies on the analysis of misreporting of food intake and on the consequences of misreporting for the interpretation of dietary surveys. Bias in the assessment of dietary intake was analysed from studies comparing reported intake with doubly labelled water assessed energy expenditure.Recent findingsThere is not yet a method for the accurate determination of dietary intake. Physical and psychological characteristics of study participants play an important role in the observed reporting bias. The degree of misreporting might increase with repeated dietary assessment in the same subjects, confounding the results of intervention studies.SummaryCampaigns aimed at changing food intake might not be as successful as concluded from the results of national food consumption measurements. Subjects might be reporting according to expected instead of real intake. In a clinical setting, the increased awareness of the nursing staff has been observed to result in overreporting of intake.

ISSN:1363-1950    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Purpose of reviewMathematical models in the study of glucose metabolism, insulin secretion and the insulin-glucose interactions have a longstanding tradition. The recent advances in this area are reviewed, with particular emphasis on the methods for the assessment of insulin sensitivity and insulin secretion. The available models are illustrated, and their common aspects and differences discussed.Recent findingsFor the assessment of insulin sensitivity and β-cell function, several modeling methods have recently been developed. Models for insulin sensitivity provide insulin-sensitivity indices from simple clinical tests, or a rich multiple-parameter characterization of insulin sensitivity from more elaborate experiments. Models for β-cell function yield indices that quantify the ability of the β-cells to respond to glucose stimuli. Furthermore, models of the insulin-glucose interactions propose interesting explanations of some experimental observations such as insulin-glucose oscillations and the progression to type 2 diabetes.SummaryMathematical models in this area continue to evolve toward more accurate and clinically applicable approaches, and should be considered as a useful resource for clinical investigators. Models also have a potentially important role for understanding the mechanisms governing the insulin-glucose regulation system.

ISSN:1363-1950    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

During pregnancy there is an increased demand for energy and protein to enable the fetus and placenta to grow. Current recommendations suggest an allowance for pregnancy of 6-10 g protein per day, however there is little consistent evidence that this is needed. Furthermore, there does not appear to be a simple relationship between the dietary protein intake of the mother and the size of the baby. If protein needs to be conserved, pregnant women must adapt metabolically. Methods for measuring protein metabolism have varied between studies. Some isotopic approaches are relatively invasive, but noninvasive methods are also available which can be used in larger numbers of women in free-living conditions. Taken together, isotopic studies during pregnancy indicate that there is a shift in the partitioning of amino acids towards net tissue deposition, reflected in an increased rate of protein synthesis, and away from oxidation, reflected in measures of urea synthesis. An understanding of the influences on fetal growth is needed to enable us to deal with the major problems in public health of our time. There is substantial evidence that impaired growth and developmentin uterois associated with a higher risk of cardiovascular and metabolic disease in adult life. In order to establish what dietary recommendations should be made, we need to explore further how women cope metabolically with the demands of pregnancy, particularly when faced with unusual demands over and above pregnancy, such as infection.

ISSN:1363-1950    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Purpose of reviewThe importance of sulfur amino acid metabolism has become increasingly apparent in recent years. Methionine and cysteine are precursors of glutathione, which plays an important role in intracellular antioxidant/free radical defenses. Homocysteine is a non-protein-bound sulfur amino acid strongly implicated in the pathogenesis of several diseases. Both glutathione and homocysteine are affected by abnormalities in sulfur amino acid metabolism that occur in the clinical setting.Recent findingsThe Storch-Young model, which determines methionine turnover and homocysteine remethylation by means of a tracer methionine infusion, has been improved by using plasma homocysteine (rather than methionine) enrichment in the model. A complex new tracer method involving the use of tracer serine, methionine, and leucine has been described to determine the effects of folate or pyridoxine deficiency on sulfur amino acid-methyl transfer reactions in humans. The etiology of hyperhomocysteinemia in chronic renal failure is controversial; new concepts in this area are described. There is new interest in the subspecies of homocysteine in the circulation. A new method is described for measuring the extremely low plasma concentrations of reduced homocysteine, using gas chromatography-mass spectrometry. PlasmaS-adenosylhomocysteine, measured by fluorescence high-performance liquid chromatography, has been suggested as being superior to homocysteine as a predictor of the risk of vascular disease.SummaryThis review highlights and critiques the above recent developments, and points out some of the complexities and pitfalls in designing and interpreting human metabolic studies involving the sulfur amino acids.

ISSN:1363-1950    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

PurposeUnderstanding the importance of euhydration in humans in order to ensure good health in various situations, the purpose of this review is to examine the available techniques in assessing hydration status.Recent findingsDuring the past 20 years, many indices have been developed to assess hydration levels accurately in humans. Changes in body weight, haematological and urine parameters, bioelectrical impedance, skinfold thickness, heart rate and blood pressure changes are among these indices. Plasma osmolality, urine osmolality and urine specific gravity are the most widely used markers of hydration. However, urine colour has also been used with reasonable accuracy when laboratory analysis is not available or when a quick estimate of hydration is necessary. Some data indicate that urine colour is as good indicator of hydration as plasma or urine osmolality or urine specific gravity.SummaryAlthough there is no ‘gold standard’ for assessment of hydration status, it appears that changes in body weight, along with urine osmolality, specific gravity, conductivity and colour are among the most widely used indices. Furthermore, they provide reasonable results, especially when the analysis is based on the first morning urine sample.

ISSN:1363-1950    

出版商:OVID    

年代:2002

数据来源: OVID