Dietary citrulline does not modify rat colon tumor response to chemotherapy, but failed to improve nutritional status.

During cancer therapy many patients experience significant malnutrition, leading to decreased tolerance to chemotherapy and decreased survival. Dietary citrulline supplementation improves nutritional status in situations such as short bowel syndrome and aging, and is of potential interest in oncology. However, a mandatory prerequisite is to test this amino acid for interaction with tumor growth and chemotherapy response. Dietary citrulline (Cit; 2%), or an isonitrogenous mix of non-essential amino acids (control), was given to Ward colon tumor-bearing rats the day before chemotherapy initiation. Chemotherapy included 2 cycles, one week apart, each consisting of one injection of CPT-11 (50 mg/kg) and of 5-fluorouracil (50 mg/kg) the day after. Body weight, food intake and tumor volume were measured daily. The day after the last injection, rats were killed, muscles (EDL, gastrocnemius), intestinal mucosa, tumor, spleen and liver were weighed. Muscle and intestinal mucosa protein content were measured. Phosphorylated 4E-BP1 was measured in muscle and tumor as a surrogate for biosynthetic activation. FRAPS (Ferric Reducing Ability of Plasma) and thiols in plasma, muscle and tumor were evaluated and plasma amino acids and haptoglobin were measured. Numerous parameters did not differ by diet overall: a) response of tumor mass to treatment, b) tumor antioxidants and phosphorylated 4E-BP1 levels, c) relative body weight and relative food intake, d) weight of EDL, gastrocnemius, intestinal mucosa, spleen and liver and e) plasma haptoglobin concentrations. Moreover, plasma citrulline concentration was not correlated to relative body weight, only cumulated food intake and plasma haptoglobin concentrations were correlated to relative body weight. Citrulline does not alter the tumor response to CPT-11/5FU based therapy but, has no effect on nutritional status, which could be due to the anorexia and the low amount of citrulline and protein ingested.

Systematic review and meta-analysis of the evidence for oral nutritional intervention on nutritional and clinical outcomes during chemo(radio)therapy: current evidence and guidance for design of future trials.

Background: Driven by reduced nutritional intakes and metabolic alterations, malnutrition in cancer patients adversely affects quality of life, treatment tolerance and survival. We examined evidence for oral nutritional interventions during chemo(radio)therapy. Design: We carried out a systematic review of randomized controlled trials (RCT) with either dietary counseling (DC), high-energy oral nutritional supplements (ONS) aiming at improving intakes or ONS enriched with protein and n-3 polyunsaturated fatty acids (PUFA) additionally aiming for modulation of cancer-related metabolic alterations. Meta-analyses were carried out on body weight (BW) response to nutritional interventions, with subgroup analyses for DC and/or high-energy ONS or high-protein n-3 PUFA-enriched ONS. Results: Eleven studies were identified. Meta-analysis showed overall benefit of interventions on BW during chemo(radio)therapy (+1.31 kg, 95% CI 0.24-2.38, P = 0.02, heterogeneity Q = 21.1, P = 0.007). Subgroup analysis showed no effect of DC and/or high-energy ONS (+0.80 kg, 95% CI -1.14 to 2.74, P = 0.32; Q = 10.5, P = 0.03), possibly due to limited compliance and intakes falling short of intake goals. A significant effect was observed for high-protein n-3 PUFA-enriched intervention compared with isocaloric controls (+1.89 kg, 95% CI 0.51-3.27, P = 0.02; Q = 3.1 P = 0.37). High-protein, n-3 PUFA-enriched ONS studies showed attenuation of lean body mass loss (N = 2 studies) and improvement of some quality of life domains (N = 3 studies). Overall, studies were limited in number, heterogeneous, and inadequately powered to show effects on treatment toxicity or survival. Conclusion: This systematic review suggests an overall positive effect of nutritional interventions during chemo(radio)therapy on BW. Subgroup analyses showed effects were driven by high-protein n-3 PUFA-enriched ONS, suggesting the benefit of targeting metabolic alterations. DC and/or high-energy ONS were less effective, likely due to cumulative caloric deficits despite interventions. We highlight the need and provide recommendations for well-designed RCT to determine the effect of nutritional interventions on clinical outcomes, with specific focus on reaching nutritional goals and providing the right nutrients, as part of an integral supportive care approach.

Prophylactic ciprofloxacin treatment prevented high mortality, and modified systemic and intestinal immune function in tumour-bearing rats receiving dose-intensive CPT-11 chemotherapy.

Infectious complications are a major cause of morbidity and mortality from dose-intensive cancer chemotherapy. In spite of the importance of intestinal bacteria translocation in these infections, information about the effect of high-dose chemotherapy on gut mucosal immunity is minimal. We studied prophylactic ciprofloxacin (Cipro) treatment on irinotecan (CPT-11) toxicity and host immunity in rats bearing Ward colon tumour. Cipro abolished chemotherapy-related mortality, which was 45% in animals that were not treated with Cipro. Although Cipro reduced body weight loss and muscle wasting, it was unable to prevent severe late-onset diarrhoea. Seven days after CPT-11, splenocytes were unable to proliferate (stimulation index=0.10+/-0.02) and produce proliferative and inflammatory cytokines (i.e., Interleukin (IL)-2, interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) IL-1beta, IL-6) on mitogen stimulation in vitro (P<0.05 vs controls), whereas mesenteric lymph node (MLN) cells showed a hyper-proliferative response and a hyper-production of pro-inflammatory cytokines on mitogen stimulation. This suggests compartmentalised effects by CPT-11 chemotherapy on systemic and intestinal immunity. Cipro normalised the hyper-responsiveness of MLN cells, and in the spleen, it partially restored the proliferative response and normalised depressed production of IL-1beta and IL-6. Taken together, Cipro prevented infectious challenges associated with immune hypo-responsiveness in systemic immune compartments, and it may also alleviate excessive pro-inflammatory responses mediating local gut injury.

Plasma and neutrophil fatty acid composition in advanced cancer patients and response to fish oil supplementation.

Metabolic demand and altered supply of essential nutrients is poorly characterised in patients with advanced cancer. A possible imbalance or deficiency of essential fatty acids is suggested by reported beneficial effects of fish oil supplementation. To assess fatty acid status (composition of plasma and neutrophil phospholipids) in advanced cancer patients before and after 14 days of supplementation (12+/-1 g day(-1)) with fish (eicosapentaenoic acid, and docosahexaenoic acid) or placebo (olive) oil. Blood was drawn from cancer patients experiencing weight loss of >5% body weight (n=23). Fatty acid composition of plasma phospholipids and the major phospholipid classes of isolated neutrophils were determined using gas liquid chromatography. At baseline, patients with advanced cancer exhibited low levels (<30% of normal values) of plasma phospholipids and constituent fatty acids and elevated 20 : 4 n-6 content in neutrophil phospholipids. High n-6/n-3 fatty acid ratios in neutrophil and plasma phospholipids were inversely related to body mass index. Fish oil supplementation raised eicosapentaenoic acid and docosahexaenoic acid content in plasma but not neutrophil phospholipids. 20 : 4 n-6 content was reduced in neutrophil PI following supplementation with fish oil. Change in body weight during the supplementation period related directly to increases in eicosapentaenoic acid in plasma. Advanced cancer patients have alterations in lipid metabolism potentially due to nutritional status and/or chemotherapy. Potential obstacles in fatty acid utilisation must be addressed in future trials aiming to improve outcomes using nutritional intervention with fish oils.

Amino acid nutrition and immune function in tumour-bearing rats: a comparison of glutamine-, arginine- and ornithine 2-oxoglutarate-supplemented diets.

Dietary supplementation with glutamine (Gln), arginine (Arg) or ornithine 2-oxoglutarate (alpha-ketoglutarate; OKG) has attracted recent attention for the potential to improve anti-cancer immune function. However, since these compounds have not been compared systematically in an internally controlled study, their relative efficacy is difficult to estimate. Buffalo rats were fed on nutritionally complete semi-purified diets supplemented with Gln, Arg or OKG for 14 days after implantation of the Morris hepatoma 7777 (n>/=7 per diet). The control diet was made isonitrogenous and isoenergetic by addition of a mixture of non-essential amino acids. After 14 days, peritoneal macrophages and splenocytes were isolated to determine cell phenotypes, macrophage cytostatic activity and natural killer (NK) cell cytotoxicity, as well as nitric oxide (NO) and cytokine production. Diet had no effect on tumour weight (1.6+/-0.2 g; n=59). However, rats fed OKG had increased macrophage cytostatic activity and NK cell cytotoxicity (P<0.05). Although enhanced killing ability by NK cells was associated with higher splenocyte NO production (P<0.04), increased cytotoxicity was not inhibited by a specific inhibitor of inducible NO synthase. The proportion of interleukin-2-receptor-positive T cells after stimulation increased in rats fed OKG (P<0.05); however, cytokine production was not affected by diet. None of OKG, Gln or Arg altered tumour growth compared with a control mixture of non-essential amino acids. These results suggest no net advantage for anti-cancer immunity, but do not preclude benefits in immune responses to disease recurrence or metastasis, therapy or secondary infection.

Dietary L-glutamine does not improve lymphocyte metabolism or function in exercise-trained rats.

Decreased glutamine availability is proposed as a mechanism for changes in immune function with intense exhaustive exercise. Less is known about the immunomodulatory effects of regular nonexhaustive exercise. To determine the effects of low intensity regular exercise and dietary glutamine supplementation on plasma glutamine concentrations, lymphocyte metabolism, and immune function, male (278 +/- 5 g) and female (182 +/- 1 g) Sprague-Dawley Buffalo rats were fed nutritionally complete casein-based semi-purified diets +/- 2% w/w glutamine. Rats were trained (21 d), as confirmed by higher (P < 0.05) succinate dehydrogenase activity in soleus muscle, to swim 2 or 4 h.d-1 or remained sedentary. Exercise lowered plasma concentrations of tryptophan, glutamate, methionine, alanine, threonine, aspartate, asparagine, and ornithine and increased the lysine concentration (P < 0.05). Neither diet nor exercise altered plasma glutamine concentrations, lymphocyte phenotypes in spleen, or the in vitro rates of splenocyte energy metabolism (production of glucose and glutamine metabolites or ATP concentrations in the incubation media). Compared with nonsupplemented rats, splenic cytolytic activity (lysis of 51Cr labeled YAC-1 cells) was reduced (P < 0.05) in the glutamine-supplemented exercising group. Under these conditions, glutamine supplementation does not appear to provide any added benefit to the exercise-trained animal.

Dietary L-glutamine supplementation reduces the growth of the Morris Hepatoma 7777 in exercise-trained and sedentary rats.

Dietary glutamine supplementation and exercise have been reported independently to enhance immune function and reduce tumor growth. We study the effect of both of these interventions on the growth of the Morris Hepatoma 7777, implanted in 59 female Sprague-Dawley Buffalo rats. Rats were fed a nutritionally complete, purified diet with or without L-glutamine 20 g/kg diet and randomized to swim 3 h/d or to remain sedentary. After 14 d, the mean tumor weight of glutamine-supplemented rats was lower (P < 0.0001) than that of unsupplemented rats (5.8 +/- 0.4 vs. 8.7 +/- 0.5 g, respectively). Exercise did not alter tumor growth. Glutamine supplementation increased [3H] thymidine incorporation by splenocytes incubated with Concanavalin A and the proportion of natural killer cells in spleen, but not cytotoxic activity against YAC-1 cells. Glutamine supplementation did not alter glutamine concentrations in plasma (691 +/- 12 mumol/L) or soleus muscle (5328 +/- 102 pmol/mg) but resulted in higher (P < 0.004) plasma concentrations of leucine, isoleucine and valine, precursors of glutamine. Splenocytes from exercised rats had a higher (P < 0.001) mitogen response than those from sedentary rats. Isolated tumor cells demonstrated high rates of non-oxidative glucose and glutamine metabolism and consumption of glutamine, tryptophan and methionine. However, neither diet nor exercise significantly affected glucose or glutamine metabolism by tumor cells. The precise mechanism of tumor growth suppression by oral glutamine supplementation is not clear but may be related to changes in substrate availability, improved tumor-directed natural killer cytotoxic activity or a faster response to an immune challenge.

Supplemental nutrition with ornithine alpha-ketoglutarate in rats with cancer-associated cachexia: surgical treatment of the tumor improves efficacy of nutritional support.

We investigated the use of ornithine alpha-ketoglutarate in treatment of rats bearing Morris hepatoma 7777. Rats received diets containing either ornithine alpha-ketoglutarate, which has been used in other catabolic states (i.e. injury, sepsis), or an isonitrogenous, isocaloric diet containing glycine. Untreated tumors grew to a mass of 11 g/100 g body weight over the 3-wk period after implantation and induced progressive anorexia, negative nitrogen balance, and body and tissue wasting. Compared with glycine, ornithine alpha-ketoglutarate had no effect on tumor growth, but also did not alter the catabolic effects of the tumor on its host. We hypothesized that capture of amino acids by the tumor limited the efficacy of supplemental nutrition here and in published reports in which tumor burden comprised 4-30% of body weight. This is supported by our observation that a 3-wk of implantation the rate of protein deposition plus amino acid oxidation by the tumor was equivalent to approximately 70% of the host's daily protein intake. To parallel the clinical situation in which tumor burden is small at diagnosis and initiation of treatment, the same diets were tested in rats treated by excision of the tumor at a limited stage of the disease. Rats received 3 d preoperative nutrition with ornithine alpha-ketoglutarate or glycine, and continued on the same diets for 3 or 6 d postoperatively. Compared with glycine-fed rats, ornithine alpha-ketoglutarate-fed rats showed a more positive nitrogen balance, higher concentrations of glutamine and branched-chain amino acids in muscle, and accelerated protein deposition in small intestine (P < 0.05). Our results explain the lack of success of nutritional support in untreated cancer and underline the need for clinically relevant animal models for further studies.

Ornithine alpha-ketoglutarate limits muscle protein breakdown without stimulating tumor growth in rats bearing Yoshida ascites hepatoma.

The growth of the Yoshida ascites hepatoma AH130 (YAH) is associated with early wasting, depletion of intracellular amino acid pools, and a pronounced activation of protein degradation in skeletal muscle of the host animal. Ornithine alpha-ketoglutarate (OKG) is used in the treatment of hypercatabolic states, and it has been suggested that it may improve nitrogen balance through repletion of free amino acid pools and suppression of protein catabolism. In cancer, OKG might similarly improve host nutritional status or stimulate tumor growth if its metabolites are limiting for tumor growth. Enteral supplementation with OKG was investigated in Sprague-Dawley rats bearing YAH. Tumor-bearing rats were compared with ad libitum- and pair-fed controls. Rats received OKG (3.4 to 4.0 g/kg body weight/d) or an equal amount of nitrogen as glycine (n = 8 in each group) for 5 days. Tumor implantation decreased cumulative food intake (-40%), host weight (-6%), skeletal muscle weight, and free amino acid levels in muscle and plasma. Muscle protein balance was estimated in vitro; decreased protein synthesis (-30%) and increased proteolysis (+113%) were observed in epitrochlearis muscles (EPI) of YAH-bearing rats compared with control groups. OKG had no effect on the wet weight (10 +/- 1 g) and nitrogen content of the tumor, or on free amino acid levels in the tumor. In tumor-bearing rats, OKG improved muscle protein balance by reducing breakdown by 33% and overall amino acid release of incubated EPI by 46%.

Dietary lipids influence insulin action.

Insulin binding and insulin responsiveness are altered by dietary fat-induced changes in the fatty acid composition of the adipocyte plasma membrane. Feeding a high P/S diet increased polyunsaturated fatty acid content of major membrane phospholipids of adipocyte plasma membrane in normal and diabetic animals, increased membrane linoleic acid content, and prevented a decrease in arachidonic acid level in diabetic animals. The high P/S diet increased insulin binding in control animals. Animals fed the high P/S diet had significantly higher rates of insulin-stimulated glucose transport and lipogenesis than did animals fed the low P/S diet. Feeding a high P/S diet significantly increased the amount of glucose transported when expressed as a function of the specific amount of insulin bound. To determine if dietary fat-induced alterations in the fatty acid composition of skeletal muscle lipid alter insulin-dependent and basal muscle metabolism, contralateral epitrochlearis and extensor digitorum longus muscles were isolated and incubated in vitro. High levels of dietary omega-3 fatty acids reduced PGE2 and PGF2 alpha synthesis in extensor digitorum longus and epitrochlearis muscle. Insulin increased glucose and amino acid transport; the increase in glucose transport by insulin was significantly greater after consumption of the high omega-3 fatty acid diet. Rats fed high levels of omega-3 fatty acids showed reduced net protein degradation in the presence and absence of insulin due to decreased rates of protein degradation and synthesis. These experiments indicate that high levels of dietary omega-3 fatty acids alter muscle membrane composition, glucose transport, and metabolism of muscle protein. To determine if dietary fatty acids alter the onset of diabetes and insulin binding to liver nuclei in spontaneously diabetic rats, weanling rats were fed chow or semipurified diets containing 20% (w/w) fat of either high or low P/S ratio. Feeding a high P/S diet increased insulin binding to liver nuclei of control and diabetic animals. Although diet did not alter the onset of diabetes, insulin binding to liver nuclei is higher in animals at the onset of diabetes than in highly diabetic animals. Eight-week-old female C57 B 6J lean and ob/ob mice were fed semipurified diets containing 20% (w/w) fat of either high or low P/S ratio to investigate the effect of diet on specific binding of insulin to liver nuclei. Insulin binding was highest in nuclei from lean mice fed a high P/S diet. Specific binding of insulin to nuclei from obese mice was also increased by the high P/S diet, but to a lesser extent.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary omega 3 fatty acid alters prostaglandin synthesis, glucose transport and protein turnover in skeletal muscle of healthy and diabetic rats.

The present study was designed to determine if dietary-fat-induced alterations in the fatty acid composition of skeletal-muscle lipid alters insulin-dependent and basal muscle metabolism, including glucose and amino acid transport, prostaglandin (PG) synthesis and protein turnover. Rats were fed on high-fat semi-purified diets providing 19% or 1% omega 3 fatty acids in the form of fish oil, for 6 weeks. After 3 weeks, half of the rats were made diabetic by a single injection of streptozotocin (50 mg/kg body wt.). After a further 3 weeks, contralateral epitrochlearis and extensor digitorum longus (EDL) muscles from each rat were incubated in vitro. High levels of dietary omega 3 fatty acids decreased PGE2 and PGF2 alpha synthesis in EDL and epitrochlearis muscle (P less than 0.0001). Diabetes and insulin had no effect on PG synthesis. Diet did not alter basal glucose or amino acid transport in EDL muscle from healthy or diabetic rats. Insulin increased glucose and amino acid transport (P less than 0.0001); the increase in glucose transport by insulin was significantly greater in muscles of rats fed on high levels of omega 3 fatty acids (P less than 0.05). Epitrochlearis from rats fed on high levels of omega 3 fatty acids showed decreased net protein degradation in the presence and absence of insulin, owing to decreased rates of protein degradation and synthesis. The data suggest that high levels of dietary omega 3 fatty acids that alter muscle membrane composition also result in alterations in glucose transport and the metabolism of muscle protein.

Prostaglandin synthesis and fatty acid composition of phospholipids and triglycerides in skeletal muscle of chicks fed combinations of flaxseed oil and animal tallow.

Chicks were fed isocaloric and isonitrogenous diets containing 6% (w/w) added fat consisting of various proportions of animal tallow and flaxseed oil (FSO). No differences among treatments were seen in growth rate, muscular deposition of protein and lipids nor in the muscle phospholipid (PL) and triglyceride (TG) contents. Prostaglandin (PG)E2 synthesis in isolated skeletal muscle was depressed significantly by feeding FSO or by treatment with naproxen (6-methoxy-alpha-methyl-2-napthaleneacetic acid), an inhibitor of PG synthesis. The changes associated with diet may be related to differences in the fatty acid composition of muscle lipids. Levels of saturated fatty acids in muscle PL and TG were relatively insensitive to dietary treatments. Monounsaturated fatty acid levels were significantly lower in the FSO-fed groups. FSO diets caused significant depression in muscle PL 20:4 omega 6 and almost completely inhibited 22:5 omega 6 incorporation. FSO diets decreased ratios of omega 6/omega 3 fatty acids and increased the unsaturation index of muscle PL. Muscles of chicks fed FSO showed increased levels of 18:3 omega 3, and of its derivatives 20:4 omega 3 and 22:5 omega 3. These results suggest that FSO inhibits PG synthesis and modifies the fatty acids of PL and TG of chick muscle. These changes may have implications for PG-dependent and/or membrane-dependent processes in muscle metabolism.

Influence of dietary flaxseed oil on the performance, muscle protein deposition, and fatty acid composition of broiler chicks.

Experiments were conducted to assess the effect of feeding flaxseed oil on the performance, muscle protein deposition, and fatty acid composition of broiler chicks. Four levels of dietary flaxseed oil were fed in combination with animal tallow to give a total of 6% added fat in the diets. The diets were isonitrogenous and isocaloric. Mortality, weight gain, feed consumption, and feed efficiency were not significantly different among treatments. Dietary treatments had no significant effects on the relative weights of the Extensor digitorum communis and Sartorius muscles nor on their protein or lipid contents. Feeding flaxseed oil resulted in increased accumulation of omega 3 fatty acids in skeletal muscle lipids. Increased amounts of desaturation and elongation products (C20:3, C20:5, C22:5, and C22:6) of alpha-linolenate (C18:3 omega 3) were observed in the Sartorius muscle lipids of chicks fed flaxseed oil. Amounts of these omega 3 fatty acids increased with duration of feeding. The amounts of omega 6 fatty acids (C20:2, C20:3, C20:4) were significantly depressed in muscle lipids after 21 days of feeding flaxseed oil. The effects of flaxseed oil on tissue amounts of individual saturated fatty acids were minimal, but amounts of monounsaturated fatty acids, especially C18:1, were depressed.