Metabolic and clinical effects of the supplementation of a functional mixture of amino acids in cerebral hemorrhage

Next-generation, personalised, model-based critical care medicine: a state-of-the art review of in silico virtual patient models, methods, and cohorts, and how to validation them

Critical care, like many healthcare areas, is under a dual assault from significantly increasing demographic and economic pressures. Intensive care unit (ICU) patients are highly variable in response to treatment, and increasingly aging populations mean ICUs are under increasing demand and their cohorts are increasingly ill. Equally, patient expectations are growing, while the economic ability to deliver care to all is declining. Better, more productive care is thus the big challenge. One means to that end is personalised care designed to manage the significant inter- and intra-patient variability that makes the ICU patient difficult. Thus, moving from current "one size fits all" protocolised care to adaptive, model-based "one method fits all" personalised care could deliver the required step change in the quality, and simultaneously the productivity and cost, of care. Computer models of human physiology are a unique tool to personalise care, as they can couple clinical data with mathematical methods to create subject-specific models and virtual patients to design new, personalised and more optimal protocols, as well as to guide care in real-time. They rely on identifying time varying patient-specific parameters in the model that capture inter- and intra-patient variability, the difference between patients and the evolution of patient condition. Properly validated, virtual patients represent the real patients, and can be used in silico to test different protocols or interventions, or in real-time to guide care. Hence, the underlying models and methods create the foundation for next generation care, as well as a tool for safely and rapidly developing personalised treatment protocols over large virtual cohorts using virtual trials. This review examines the models and methods used to create virtual patients. Specifically, it presents the models types and structures used and the data required. It then covers how to validate the resulting virtual patients and trials, and how these virtual trials can help design and optimise clinical trial. Links between these models and higher order, more complex physiome models are also discussed. In each section, it explores the progress reported up to date, especially on core ICU therapies in glycemic, circulatory and mechanical ventilation management, where high cost and frequency of occurrence provide a significant opportunity for model-based methods to have measurable clinical and economic impact. The outcomes are readily generalised to other areas of medical care.

Morbid obesity in a young woman affected by advanced chronic kidney disease: an exceptional case report. Does a high dose of essential amino acids play a key role in therapeutic success?

A 38-year-old woman, obese (219 kg), diabetic, hypertensive, chronic kidney disease (CKD) stage 4, with low plasma albumin level (2.9 g dl⁻¹) and marked proteinuria (22 g per day) was studied. Given the advanced-stage CKD with nephrotic proteinuria, we supplemented low-protein diet with high doses of a tailored essential amino acid mixture (AAs: 44 g per day) to improve weight reduction in the patient. After 20 months of conservative therapy, the patient lost 43 kg; despite two episodes of infection, albumin plasma levels increased up to 3.7 g per day. After a further 20 months of dialysis, the patient maintained a diet of 1800 kcal supplemented with 32 g of AAs and lost 47 kg, whereas both albumin (3.89±0.12 g dl⁻¹) and C reactive protein returned to normal. During the follow-up period, anemia improved, erythropoietin was thus discontinued and insulin requirement decreased to 105 IU. This therapeutic option may be beneficial in advanced CKD patients with obesity and diabetes resulting from malnutrition.

Supplementation of essential amino acids may reduce the occurrence of infections in rehabilitation patients with brain injury

BACKGROUND

To investigate whether supplementation with oral essential amino acids (EAAs) may reduce the occurrence of nosocomial infection among patients with brain injury (BI: stroke, trauma, anoxic coma).

METHODS

Patients (n = 125; 77 men, 48 women; mean age 63 ± 15 years) with stroke (68.8%), subarachnoid hemorrhage (17.6%), traumatic BI (7.2%), and anoxic BI (6.4%) 88 ± 15 days after the index event. Patients were randomly assigned to 2 months of oral EAAs (n = 63; 8 g/d) or placebo (n = 62).

RESULTS

Over the first month of rehabilitation, there were 60 infections in the whole population of 125 patients (48%); however, the rate was 23.2% lower in the EAA group (23 episodes/63 patients; 36.5%) than in the placebo group (37 episodes/62 patients; 59.7%) (P < .01). The types of infection were similarly distributed between the 2 groups. Serum levels of prealbumin <20 mg/dL and C-reactive protein (CRP) >0.3 mg/dL were the best predictors of future infection (prealbumin: odds ratio [OR] = 4.17, confidence interval [CI] 1.84-9.45, P < .001; CRP: OR = 3.8, CI 1.71-8.44, P < .001).

CONCLUSION

Supplementary EAAs may reduce the occurrence of nosocomial infections in rehabilitation patients with BI. Prealbumin and CRP are the best predictors of future infections.

Clinical use of amino acids as dietary supplement: pros and cons

Nitrogen supply is pivotal for the maintenance of life. Amino acids can be utilized to synthesize both glucose and lipids. The opposite, i.e., production of amino acids from either one of them, is not possible in the absence of other amino acids as donors of nitrogen. The quality of amino acid content in protein has been re-evaluated recently, and the relevance of essential amino acids has been repeatedly underlined. Essential amino acid requirements in different mammals are not identical, and ratios among them should be taken into account when projecting an efficient formulation. Recent research has demonstrated that genes respond to different qualities and quantities of nutritional supply, and increased provision of essential amino acids increases lifespan in animal experiments through mitochondriogenesis and maintenance of elevated rates of synthesis of anti-oxidant molecules. Moreover, genetic expression of key controllers of synthesis, like mTOR, may be particularly important for understanding skeletal muscle maintenance. Losses of muscle mass and impaired immune function are related to reduced protein supply, and there is increasing evidence that regular essential amino acid intake as part of an oral diet is effective in reversing muscle catabolism, promoting muscle anabolism, and restoring immunological function. Therefore, the use of amino acids as supplements to diet would be expanding in the near future. Is this safe? Few data are available on amino acid toxicity, and only one essential amino acid may be considered to have clinically relevant toxicity: methionine, because it is transformed into a toxic intermediate, homocysteine, when cysteine synthesis is required by metabolic needs. Matching of stoichiometric ratios between methionine and cysteine may solve the problem of supplying sufficient amounts of sulfur to the body. Arginine and glutamine are two non-essential amino acids than can become "conditionally essential" because of elevated needs during pathological conditions, and metabolism may not be able to maintain their concentrations at sufficient levels to match metabolic requirements. Chronic exogenous arginine supplementation has not proven to exert positive clinical effects in different trials, and sequential articulation of the knowledge of introduction of arginine-driven transcriptional, translational, and epigenetic adaptations may give us a key for interpreting those puzzling results.