Lactate and the GPR81 receptor in metabolic regulation: implications for adipose tissue function and fatty acid utilisation by muscle during exercise

Lactate is increasingly recognised to be more than a simple end product of anaerobic glycolysis. Skeletal muscle and white adipose tissue are considered to be the main sites of lactate production and release. Recent studies have demonstrated that there is a specific G-protein coupled receptor for lactate, GPR81, which is expressed primarily in adipose tissue, and also in muscle. Lactate inhibits lipolysis in adipose tissue by mediating, through GPR81, the anti-lipolytic action of insulin. A high proportion (50% or more) of the glucose utilised by white adipose tissue is converted to lactate and lactate production by the tissue increases markedly in obesity; this is likely to reflect a switch towards anaerobic metabolism with the development of hypoxia in the tissue. During exercise, there is a shift in fuel utilisation by muscle from lipid to carbohydrate, but this does not appear to be a result of the inhibition of lipolysis in the main adipose tissue depots by muscle-derived lactate. It is suggested instead that a putative autocrine lactate loop in myocytes may regulate fuel utilisation by muscle during exercise, operating via a muscle GPR81 receptor. In addition to being an important substrate, lactate is a key signal in metabolic regulation

Changes in walking speed following resistance training in people with multiple sclerosis: a systematic review and meta-analysis

BackgroundReduced walking ability, especially decreased gait speed, is one of the most common and disabling impairments reported by people with multiple sclerosis (MS). Considering the impact of muscle strength on walking ability, resistance training may have the potential to improve walking speed in MS. Therefore, this systematic review and meta-analysis aims to evaluate the effect of lower limb resistance training on walking speed in people with MS.MethodsSeven databases (CINAHL, MEDLINE, The Allied and Complimentary Medicine Database, Web of Science, Physiotherapy Evidence Database [PEDro], PsycINFO, and Sports Medicine and Education Index) were searched in March 2024 for studies that met the following eligibility criteria: randomized controlled trials investigating the effects of resistance training interventions on objective measures of walking speed in people with MS. Risk of bias was assessed using the PEDro scale. Meta-analysis was performed to quantify intervention effect using a random effects model.ResultsTwelve randomized controlled trials were included, reporting data on 425 individuals with MS. Participants had mostly relapsing–remitting MS (85%) and a mild–moderate level of disability (Expanded Disability Status Score 1.0–6.0). Results of the meta-analysis (based on 7 of the included studies) indicated a significant yet variable improvement in walking speed in favor of the intervention (0.10 m/s, 95% confidence interval 0.01–0.19, p < .05). Sensitivity analysis indicates that larger improvements in walking speed were found over tests covering shorter distances.ConclusionsResistance training was found to significantly improve walking speed in people with MS. However, variability in results were noted across studies; accordingly, future research should determine how variables—particularly related to resistance training prescription—influence the intervention effect

A Methodological Comparison of Giving Surveys: Indiana as a Test Case

Every 4 years, the Center on Philanthropy at Indiana University conducts a telephone survey (called Indiana Gives) of the giving and volunteering behaviors of Indiana citizens. In preparing to conduct Indiana Gives for 2000, a larger methodological question was asked: How much does survey methodology matter in generating accurate measures of giving and volunteering? In this most recent wave of the Indiana survey, conducted in October and November 2000, eight groups of approximately 100 randomly selected Indiana residents were asked to complete one of eight surveys related to giving and volunteering. It was found that the longer the module and the more detailed its prompts, the more likely a household was to recall making any charitable contribution and the higher the average level of its giving. These differences persisted even after controlling for differences in age, educational attainment, income, household status, race, and gender.ARNOV

Inversion and Representation Theorems for the Laplace Transformation

A study is made of the Laplace transformation on Banach-valued functions of a real variable, with particular reference to inversion and representation theories. First a new type of integral for Banach-valued functions of a real variable, the "Improper Bochner" integral is defined. The relations between the Bochner, Improper Bochner, Riemann-Graves, and Riemann-Stieltjes integrals are studied. Next, inversion theorems are proved for a new "real" inversion operator when the integral in the Laplace transformation is each of the above mentioned types. Lastly, representation of Banach-valued functions by Laplace integrals of functions in Bp([0,∞);¥), 1 ≤ p < ∞, is studied, and theorems are very like those proved, for numerically-valued functions, by D. V. Widder in his book "The Laplace Transform" (Princeton, 1941) page 312. The classes Hp(α ; ¥), 1 ≤ p < ∞, are also studied in this section as is the representation of numerically-valued functions by Laplace-Stieltjes integrals

Recent Decisions

Comments on recent Decisions by Paul J. Driscoll, William E. Kelly, George W. Vander Vennet, Paul K. Rooney, Richard C. Wilbur, Harold E. McKee, and Theodore E. Fitzgerald