The metabolic response to yellow fever immunization: protein-sparing modified fast

Ketogenic diets as treatment of obesity and type 2 diabetes mellitus

During the last decades, several interventions for the management of overweight and obesity have been proposed. Among diets, the first studies focused on the effect of water only and total fasting diets with or without proteins. Unfortunately, they were found to be associated with adverse events which lead to the abandon of these strategies. Interestingly, despite the radical approach, total fasting was effective and generally well tolerated. A strict connection between protein-calorie malnutrition and increased in morbidity and mortality in hospitalized patients was found at that time. Then, the seminal works of Blackburn and his collaborators lead to the introduction of the protein-sparing modified fast. Encouraged by the early results using this intervention, diets evolved to the current very-low-calorie ketogenic diets (VLCKD). In the present review, results of studies on the VLCKDs are presented and discussed, with a particular reference to the protocolled VLCKD. Also, a recent proposal on the nomenclature on the ketogenic diets is reported. Available evidence suggests VLCKDs to be effective in achieving a rapid and significant weight loss by means of an easily reversible intervention which could be repeated, if needed. Muscle mass and strength are preserved, resting metabolic rate is not impaired, hunger, appetite and mood are not worsened. Symptoms and abnormal laboratory findings can be there, but they have generally been reported as of mild intensity and transient. Preliminary studies suggest VLCKDs to be a potential game-changer in the management of type 2 diabetes too. Therefore, VLCKDs should be considered as an excellent initial step in properly selected and motivated patients with obesity or type 2 diabetes, to be delivered as a part of a multicomponent strategy and under strict medical supervision.

Metabolic and Inflammatory Effects of an ω-3 Fatty Acid-Based Eucaloric Ketogenic Diet in Mice With Endotoxemia

BACKGROUND

Dietary strategies can aid in the management of critically ill patients. Very-low-carbohydrate diets have been shown to improve glucose control and the inflammatory response. We aimed to determine the effects of a eucaloric ketogenic diet (EKD) enriched with ω-3 fatty acids (O3KD) on glucose levels and inflammation in mice with endotoxemia.

METHODS

Adult mice were fed 1 of 3 diets (control diet [CD], EKD, or O3KD). After 4 weeks, each group received saline or Escherichia coli lipopolysaccharide (LPS) (5 mg/kg) intraperitoneally during the postprandial (PPP) or postabsorptive (PAP) periods. Blood glucose was measured at 0, 15, 30, 60, 90, 120, 180, and 240 minutes. Serum tumor necrosis factor (TNF)-α and interleukin (IL) 6 were measured by enzyme-linked immunosorbent assay. Distribution of serum fatty acids was determined by gas liquid chromatography. Hepatic expression of genes involved in inflammation, as well as glucose and lipid metabolism, were determined by quantitative polymerase chain reaction.

RESULTS

During the PPP, glucose curves were comparable among the experimental groups. During the PAP, EKD showed a more pronounced increase in glucose levels at the first hour after LPS challenge compared with the CD-LPS group. During the PAP, IL6 was lower in O3KD-LPS compared with CD-LPS and EKD-LPS groups. These differences disappeared in the PPP. Similarly, TNF-α was lower in the O3KD-LPS group compared with the EKD-LPS group. The O3KD significantly increased the serum levels of the ω-3 eicosapentaenoic and docosahexaenoic acids and decreased the ω-6 arachidonic acid.

CONCLUSION

An O3KD leads to reduced inflammation and maintains glucose homeostasis in mice with endotoxemia.

Some Musings About Differential Energy Metabolism With Ketogenic Diets

Ketogenic states are of 3 major types: total starvation and those resulting from the consumption of semistarvation, ketogenic diets, and eucaloric ketogenic diets. All are characterized by little or no dietary carbohydrate, resulting in a fat-based metabolism with sustained ketonemia of varying degrees in each state. The latter 2 diets are clinically useful with important impacts on both aspects of the energy balance equation with increased satiety and less hunger on the intake side and probably increased energy expenditure on the output side; both may have important implications for the successful long-term management of obesity. Consideration of older research regarding the hormonal response to carbohydrate-free dieting and recent findings on hepatic glycogen status that occurs with sustained ketonemia support the likelihood that there are profound differences in 24-hour gluconeogenesis rates between ketogenic diets and balanced diets containing substantial carbohydrate. This metabolic distinction could have a meaningful impact to increase the thermic effect of feeding and daily energy expenditure amounting to 100 kcal/d or more with each of the ketogenic diets.

Protein sparing therapies in acute illness and obesity: a review of George Blackburn's contributions to nutrition science

Protein sparing therapies were developed to mitigate the harms associated with protein-calorie malnutrition and nitrogen losses induced by either acute illness or hypocaloric diets in patients with obesity. We review the development of protein sparing therapies in illness and obesity with a focus on the pioneering contributions of George Blackburn, MD, PhD. He recognized that protein-calorie malnutrition is a common and serious clinical condition and developed new approaches to its treatment in hospitalized patients. His work with stable isotopes and with animal models provided answers about the physiological nutritional requirements and metabolic changes across a spectrum of conditions with varying degrees of stress and catabolism. This led to improvements in enteral and parenteral nutrition for patients with acute illness. Blackburn also demonstrated that lean body mass can be preserved during weight loss with carefully designed very low calorie treatments which became known as the protein sparing modified fast (PSMF). We review the role of the PSMF as part of the comprehensive management of obesity.

Pathogenesis and Pathophysiology of Yellow Fever

It will be apparent to the reader that there is much to learn about the pathogenesis of YF. The role of specific genes and molecular determinants of neurotropism and viscerotropism has been defined only partially. The availability of infectious clones and a small animal (hamster) model should allow dissection of virulence factors, which can then be tested in the more difficult monkey model. The marked differences between wild-type YF strains should be evaluated by evaluating the relationships between virulence and genome sequence. The role of cytokine dysregulation and endothelial injury in YF will be elucidated as access to patients and of patients to more sophisticated medical care improves. The number of cases of YF in unvaccinated travelers hospitalized after return from the tropics has unfortunately increased, but such cases afford unique opportunities to study the pathogenesis of renal failure, coagulopathy, vascular instability, and shock, as well as new treatment modalities. At the cellular level, there are also important opportunities for research on YF virus-cell receptor interactions, the control of apoptotic cell death, and the predilection for cells of the midzone of the liver lobule. The role of dendritic cells in the early stage of YF infection is deserving of study. Finally, the role of the immune response to infection, particularly cellular immunity, is poorly characterized, and the suggestion that immune clearance may aggravate the condition of the host during the period of intoxication should be evaluated in appropriate animal models.