Renal metabolism of amino acids: its role in interorgan amino acid exchange

The kidneys play a role in the synthesis and interorgan exchange of several amino acids. The quantitative importance of renal amino acid metabolism in the body is not, however, clear. We review here the role of the kidney in the interorgan exchange of amino acids, with emphasis on quantitative aspects. We reviewed relevant literature by using a computerized literature search (PubMed) and checking relevant references from the identified articles. Our own data are discussed in the context of the literature. The kidney takes up glutamine and metabolizes it to ammonia. This process is sensitive to pH and serves to maintain acid-base homeostasis and to excrete nitrogen. In this way, the metabolism of renal glutamine and ammonia is complementary to hepatic urea synthesis. Citrulline, derived from intestinal glutamine breakdown, is converted to arginine by the kidney. Renal phenylalanine uptake is followed by stoichiometric tyrosine release, and glycine uptake is accompanied by serine release. Certain administered oligopeptides (eg, glutamine dipeptides) are converted by the kidneys to their constituent components before they can be used in metabolic processes. The kidneys play an important role in the interorgan exchange of amino acids. Quantitatively, for several important amino acids, the kidneys are as important as the gut in intermediary metabolism. The kidneys may be crucial "mediators" of the beneficial effects of specialized, disease-specific feeding solutions such as those enriched in glutamine dipeptides.     

Reduced total energy expenditure and physical activity in cachectic patients with pancreatic cancer can be modulated by an energy and protein dense oral supplement enriched with n-3 fatty acids

The aim of the study was to assess the total energy expenditure (TEE), resting energy expenditure (REE) and physical activity level (PAL) in home-living cachectic patients with advanced pancreatic cancer. The influence of an energy and protein dense oral supplement either enriched with or without the n-3 fatty acid eicosapentaenoic acid (EPA) and administered over an 8-week period was also determined. In total, 24 patients were studied at baseline. The total energy expenditure was measured using doubly labelled water and REE determined by indirect calorimetry. Patients were studied at baseline and then randomised to either oral nutritional supplement. Measurements were repeated at 8 weeks. At baseline, REE was increased compared with predicted values for healthy individuals (1387(42) vs 1268(32) kcal day(-1), P=0.001), but TEE (1732(82) vs 1903(48) kcal day(-1), P=0.023) and PAL (1.24(0.04) vs 1.50) were reduced. After 8 weeks, the REE, TEE and PAL of patients who received the control supplement did not change significantly. In contrast, although REE did not change, TEE and PAL increased significantly in those who received the n-3 (EPA) enriched supplement. In summary, patients with advanced pancreatic cancer were hypermetabolic. However, TEE was reduced and this was secondary to a reduction in physical activity. The control energy and protein dense oral supplement did not influence the physical activity component of TEE. In contrast, administration of the supplement enriched with EPA was associated with an increase in physical activity, which may reflect improved quality of life.     

The response of leptin, interleukin-6 and fat oxidation to feeding in weight-losing patients with pancreatic cancer

At baseline, weight-losing pancreatic cancer patients (n=7) had lower leptin (P<0.05) but higher cortisol, interleukin-6, resting energy expenditure and fat oxidation than healthy subjects (n=6, P<0.05). Over a 4 h feeding period, the areas under the curve for glucose, cortisol and interleukin-6 were greater (P<0.05), but less for leptin in the cancer group (P<0.05). Therefore, it would appear that low leptin concentrations, increased fat oxidation and insulin resistance are associated with increased concentrations of cortisol and interleukin-6 in weight-losing patients with pancreatic cancer.     

Acupuncture for postchemotherapy fatigue: a phase II study.

PURPOSE: To determine whether improvement in postchemotherapy fatigue following acupuncture treatment is substantial enough to warrant a controlled trial. PATIENTS AND METHODS: We accrued patients at Memorial Sloan-Kettering Cancer Center who had completed cytotoxic chemotherapy but experienced persisting fatigue. Patients with severe anemia, clinical depression, or Karnofsky performance status score less than 70 were excluded. Thirty-seven patients were registered in two cohorts; 31 provided follow-up data. Patients received acupuncture either twice per week for 4 weeks (25 patients) or once per week for 6 weeks (12 patients). The primary end point was change in score on the Brief Fatigue Inventory between baseline and 2 weeks after the final treatment. A baseline Brief Fatigue Inventory score of four or greater was an eligibility requirement for the trial. RESULTS: Patients had completed cytotoxic chemotherapy an average of more than 2 years previously. Baseline fatigue scores were high, with approximately half of the sample scoring in the "severe" range. Mean improvement following acupuncture was 31.1% (95% CI, 20.6% to 41.5%), meeting our prespecified criterion for declaring acupuncture worthy of further study. Increasing age was associated with poorer response and failure to complete the study. There was no important difference in improvement following once-weekly and twice-weekly treatments. CONCLUSION: Acupuncture is worthy of further study in the treatment of postchemotherapy fatigue.     

Towards a cognitive model and measure of dissociation

Dissociation comprises a range of psychological processes, which have largely been the subject of psychodynamic discussion. Dissociative phenomena are for the most part unaddressed by cognitive theorists. Current measures are atheoretical and our understanding of dissociation has been hampered by the absence of clear psychological models. This paper describes a new cognitive model of dissociation and the development and validation of a theoretically based measure-the Wessex Dissociation Scale (WDS). The WDS has adequate internal consistency, shows convergent validity with the Dissociative Experiences Scale (DES-II), and is equivalent to the DES-II in its associations with severe psychopathology. However, the WDS has some advantages over the DES-II, in that it is sensitive to milder manifestations of dissociation, demonstrating links to less severe pathologies. The findings described here provide preliminary support for the usefulness of the cognitive model, and the varied consequences of dissociative processes. The clinical and research utility of the model and the scale are discussed.