Long-Term Results Following Antibiotic Treatment of Acute Appendicitis in Adults.

BACKGROUND: Antibiotic treatment of acute appendicitis has gained interest and inquiries. Reports have demonstrated both safety and high resolution of symptoms and inflammation following antibiotic treatment of appendicitis, but information on long-term results is required. Our present aim was therefore to evaluate long-term recurrence rate of initial antibiotics-alone treatment for suspected acute appendicitis. METHODS: Patients with favourable response to antibiotics in earlier randomized (RCT, n = 97) and population-based (PBT, n = 342) studies as well as subsequently treated non-randomized (Non-R, n = 271) patients are evaluated for long-term risk to relapse demanding surgical appendectomy; altogether 710 patients. RESULTS: Clinical characteristics among randomized and non-randomized patients were similar without any statistical difference according to abdominal symptoms and degree of systemic inflammation (CRP, WCC) when antibiotic treatment started. Females and males showed the same results. The median follow-up time was 2162 days (5.92 years), and the range across highest and lowest follow-up was 3495 days (range 2-3497) for the entire group, without significant differences among subgroups (RCT, PBT, Non-R). The cumulative probability for relapse of appendicitis demanding appendectomy was: 0.09, 0.12, 0.12 and 0.13 at 1-, 2-, 3- and 5-year follow-up, with a probability of 0.86 ± 0.013 without appendectomy after 8 years. This may imply an overall benefit of 60-70% by antibiotics during expected 10-year follow-up accounting for initial treatment failures at 10-23% in our published reports. CONCLUSION: Antibiotic treatment is safe and effective as a first-line therapy in unselected adults with acute appendicitis with a risk around 15% for long-term relapse following favourable initial treatment response.

Randomized clinical trial of antibiotic therapy versus appendicectomy as primary treatment of acute appendicitis in unselected patients.

BACKGROUND: A trial in selected men suggested that antibiotic therapy could be an alternative to appendicectomy in appendicitis. This study aimed to evaluate antibiotic therapy in unselected men and women with acute appendicitis. METHODS: Consecutive patients were allocated to study (antibiotics) or control (surgery) groups according to date of birth. Study patients received intravenous antibiotics for 24 h and continued at home with oral antibiotics for 10 days. Control patients had a standard appendicectomy. Follow-up at 1 and 12 months was carried out according to intention and per protocol. RESULTS: Study and control patients were comparable at inclusion; 106 (52.5 per cent) of 202 patients allocated to antibiotics completed the treatment and 154 (92.2 per cent) of 167 patients allocated to appendicectomy had surgery. Treatment efficacy was 90.8 per cent for antibiotic therapy and 89.2 per cent for surgery. Recurrent appendicitis occurred in 15 patients (13.9 per cent) after a median of 1 year. A third of recurrences appeared within 10 days and two-thirds between 3 and 16 months after hospital discharge. Minor complications were similar between the groups. Major complications were threefold higher in patients who had an appendicectomy (P < 0.050). CONCLUSION: Antibiotic treatment appears to be a safe first-line therapy in unselected patients with acute appendicitis. REGISTRATION NUMBER: NCT00469430 (http://www.clinicaltrials.gov).

Transport kinetics of amino acids across the resting human leg.

Flux rates of amino acids were measured across the leg after an overnight fast in resting human volunteers. A balanced amino acid solution was, after a primed infusion, continuously infused for 2 h at each of three step-wise and increasing rates corresponding to 8.3, 16.7, 33.2 mg N/kg per h that were equivalent to 0.2, 0.4, 0.8 g N/kg per d. Flux of amino acids across the leg was compared with the flux of glucose, glycerol, lactate, free fatty acids, and oxygen. The size of the muscular tissue pool of amino acids was measured. Whole body amino acid oxidation was estimated by means of the continuous infusion of a 14C-labeled mixture of amino acids. Arterial steady state levels were obtained for most amino acids within 30 to 45 min after the primed constant infusion. Leg flux of amino acids switched from a net efflux after an overnight fast to a balanced flux between infusion rates corresponding to 0.2-0.4 g N/kg per d. At 0.8 g N/kg per d essentially all amino acids showed uptake. The infusion of amino acids stimulated leg uptake of glucose and lactate production and decreased FFA release. Oxygen uptake and leg blood flow increased significantly with increased infusion of amino acids. There was significant variability in transport rate among individual amino acids. Branched chain amino acids showed rapid transport and methionine slow transport rate. Only small changes in the muscle tissue concentration of certain amino acids were registered after 6 h of amino acid infusion despite uptake for several hours. When amino acids were infused at a rate corresponding to 0.8 g N/kg per d, the leg uptake of amino acids was 6% and the simultaneous whole body oxidation of infused amino acids was approximately 10%. Net uptake of leucine across the leg per hour was 62% of the muscle pool of free leucine when amino acids were infused at a rate corresponding to 0.4 g N/kg per d. Multiple regression analysis showed that the arterial concentration of an amino acid was the most important factor for uptake, more so than insulin concentration and blood flow. It is concluded that leg exchange of amino acids is large enough to rapidly change the pool size of the amino acids in skeletal muscle, if not counter-regulated by changes in rates of protein synthesis and degradation. Estimates of the capacity for protein synthesis and transfer RNA acceptor sites in muscles agree in order of magnitude with the net uptake of amino acids at high infusion rates of amino acids. Therefore, measurements of the balance of tyrosine, phenylalanine, and particularly methionine at steady state may reflect net balance of proteins across skeletal muscles even in short-time experiments.

Enteral (oral or tube administration) nutritional support and eicosapentaenoic acid in patients with cancer: a systematic review.

The aim of this systematic review was to determine the efficacy and potential benefits of enteral nutritional support [oral nutritional supplements (ONS) or enteral tube feeding (ETF)], and eicosapentaenoic acid (EPA, free acid, ethyl esters or fish oil; provided as capsules or enriched ONS or ETF) in patients with cancer. Clinical studies were identified using electronic databases, and studies were selected according to predetermined criteria. For each treatment modality (chemo/radiotherapy, surgery, and palliative care), the comparisons of interest were nutritional support vs. routine care (no nutritional support), EPA supplement (capsule or enriched ONS or ETF) vs. routine care (no supplement or standard supplement), ETF vs. parenteral nutrition (PN). The reviewed outcomes were dietary intake, anthropometry, clinical (mortality, length of hospital stay, complications, and quality of life) and haematological/biochemical (white blood cell count, serum transferrin and albumin, CD3-positive lymphocytes, and inflammatory markers). Meta-analyses were performed where possible. In patients undergoing radiotherapy, meta-analysis showed that ONS significantly increase dietary intake (381 kcal/day, 95% CI 193 to 569 in 3 RCTs) compared to routine care. In patients undergoing surgery, meta-analyses showed that ETF results in a significantly shorter length of hospital stay (1.72 fewer days, 95% CI 0.90 to 2.54 in 8 RCTs), lower incidence of any complications (OR 0.62, 95% CI 0.50 to 0.77 in 4 RCTs) and infectious complications (OR 0.67, 95% CI 0.55 to 0.82 in 11 RCTs) and lower sepsis scores (2.21 points, 95% CI 1.49 to 2.92 in 2 RCTs), but no difference in mortality (OR 0.72, 95% CI 0.40 to 1.29 in 7 RCTs) compared to PN. There was also no difference in mortality between ONS or ETF vs. routine care in patients undergoing chemotherapy/radiotherapy (OR 1.00, 95% CI 0.62-1.61 in 4 RCTs) or surgery (OR 2.44, 95% CI 0.75 to 7.95 in 4 RCTs). Individual studies of EPA supplementation as capsules showed improvements in survival, complications and inflammatory markers in patients undergoing bone marrow transplant (BMT). In palliative care patients receiving EPA-enriched ONS or capsules, there were inconsistent positive effects on survival and quality of life. In those undergoing surgery, EPA-enriched ETF had no effect. Further research is required to elucidate the clinical efficacy of enteral nutrition support, including the potential benefits of EPA supplementation, in patients with cancer.

Role of insulin in development of cancer cachexia in nongrowing sarcoma-bearing mice: special reference to muscle wasting.

This study evaluated whether altered insulin metabolism is a key factor behind weight loss during sarcoma growth in nongrowing mice (C57BL/6J). Fasted sarcoma-bearing mice had decreased blood glucose concentrations but unchanged levels of insulin, compared with those in pair-weighed and freely fed controls. During refeeding, insulin levels were inappropriately low for the degree of glycemia in sarcoma-bearing mice compared with those of pair-weighed and freely fed controls. Injections ip of glucose to tumor-bearing animals resulted in insulin levels comparable to postabsorptive values in healthy control animals, indicating that hypoinsulinemia in freely eating tumor-bearing animals was due to a reduced glycemic sensitivity for pancreatic insulin release. Insulin supplementation at doses [4 IU/100 g (body wt)] that increase body fat in normal animals could not protect the tumor-bearing host from progressive loss of body fat or lean tissues. Exogenous insulin in excess of endogenous insulin production did not stimulate tumor growth. Nitrogen and RNA-DNA content were significantly decreased in the quadriceps muscle of tumor-bearing mice. This reduction was independent of altered insulin levels and could not be prevented by exogenous insulin. The depressed capacity of protein synthesis in extensor digitorum longus (EDL) muscle could be entirely attributed to the state of malnutrition in tumor-bearing animals. The sensitivity and responsiveness of protein synthesis in EDL muscles to insulin were normal in tumor-bearing mice, regardless of whether exogenous insulin exerted its effect in vivo or in vitro. This study confirms insulin resistance for glucose metabolism in an experimental sarcoma animal model. Such changes are concluded to be secondary to anorexia and necessary to counteract hypoglycemia. In non-growing sarcoma-bearing mice, malnutrition and anorexia account entirely for depressed muscle protein synthesis, which is not explained by insulin resistance at the translational level. Insulin metabolism is not a key factor behind progression of wasting in sarcoma-bearing mice, but anorexia is.

Tumor-host wasting not explained by adrenal hyperfunction in tumor-bearing animals.

This study addressed the question of whether hypercorticism in tumor-bearing animals contributes to the wasting of body fat and lean body mass, particularly that of skeletal muscles. For this purpose, hydrocortisone-substituted nongrowing sarcoma-bearing and control C57BL/6J mice were used that were either adrenalectomized or sham-operated prior to experimentation. Adrenalectomy in itself did not alter food intake or body composition in normal animals. Tumor-bearing mice and pair-weighted control animals had elevated urinary excretion of corticosteroids compared with the urinary excretion in freely fed controls. The malignant tumor induced the well-recognized wasting in tumor-bearing animals, irrespective of the presence of the adrenal glands. Therefore, an elevated corticosteroid production did not account for the wasting of body fat, lean body mass, skeletal muscle proteins, or decreased RNA activity in quadriceps muscles from tumor-bearing animals, although such muscles were sensitive to physiologic doses of injected hydrocortisone (20 micrograms/day). Tyrosine aminotransferase (TAT) activity in liver tissue from tumor-bearing animals was higher than that induced by pharmacologic doses of hydrocortisone in normal animals. Physiologic doses of hydrocortisone induced hepatic TAT activity, but pair-weighed control animals with the same degree of hypercorticism as was found in tumor-bearing animals had normal TAT activity in liver tissue. Although hypercorticism is present in tumor-bearing animals, the results demonstrate that cancer cachexia can start and proceed independently of the adrenal glands. Therefore, adrenal hyperfunction is not the proximate cause for the development of experimental cancer cachexia induced by anorexia.

Growth hormone and experimental cancer cachexia.

Plasma levels of growth hormone (GH) and the effect of GH treatment have been evaluated in adult nongrowing sarcoma-bearing mice (C57BL/6J). Prepubertal tumor-bearing mice, tumor-bearing hypophysectomized Sprague-Dawley rats, and malnourished non-tumor-bearing animals served as additional groups of study and control animals. Adult sarcoma-bearing mice showed an increase in plasma levels of GH early following tumor implantation. GH levels increased further with tumor progression. The anorexia and the state of malnutrition in sarcoma-bearing mice were the major factors behind increased GH levels. Muscle wasting and body composition in the tumor-bearing host were not improved by GH treatment at doses that increased growth rate in normal growing mice with intact pituitaries or partially normalized growth rate in hypophysectomized rats. Exogenous GH supported tumor growth and host body growth to the same extent in hypophysectomized rats. Exogenous GH in excess of endogenous GH did not stimulate tumor growth further. It is suggested that increased GH production in a tumor-bearing host acts in concert with other hormones to stimulate endogenous substrate mobilization and in tumor-bearing animals to prevent substrate deficiency and hypoglycemia. On the basis of this conclusion, it is unlikely that GH supplementation to a freely eating tumor-bearing host will support replenishment of host tissues.

Thyroid hormones and experimental cancer cachexia.

The relationship between circulating thyroid hormones and nutritional status was studied in sarcoma-bearing inbred C57BL/6J mice and control mice. Supplementation with exogenous thyroxine (T4) was also evaluated. Tumor-bearing animals had depressed levels of circulating thyroid hormones. This was also found in food-restricted (pair-fed and pair-weighed) controls. Plasma levels of thyroid hormones decreased with increased tumor burden. Thyrotropin-releasing hormone caused an increased response of thyroid-stimulating hormone in tumor-bearing animals. Low levels of thyroid hormones in sarcoma-bearing mice were due to depressed hormone production by the thyroid gland rather than to increased clearance rate of hormones. Plasma levels of triiodothyronine (T3) correlated to the amount of whole-body nitrogen among sarcoma-bearing mice and food-restricted controls. Exogenous T4 increased food intake by 20% in sarcoma-bearing mice. The benefit of this was probably counteracted by an increased metabolic rate, since reversal of plasma levels of T3 and free T4 had no net effect on body composition of freely eating sarcoma-bearing mice, although it had a negative effect on body and muscle composition in food-restricted controls. Exogenous T4 did not stimulate tumor growth. The results indicate that low circulating levels of thyroid hormones in experimental cancer cachexia are probably caused by the reduced food intake (anorexia), which is in agreement with findings in clinical cancer. Depression of thyroid hormones is probably a physiological means to reduce energy expenditure and to preserve substrates in progressive cancer disease.

Lack of evidence for elevated breakdown rate of skeletal muscles in weight-losing, tumor-bearing mice.

Protein degradation was measured as tyrosine release rate from proteins of extensor digitorum longus (EDL) muscles and as urinary excretion of 3-methylhistidine in freely fed adult nongrowing C57BL/6J mice with sarcomas, to study protein degradation in cancer-induced wasting of skeletal muscles. Whole muscle protein breakdown rate was unchanged, whereas protein synthesis was depressed, leading to an increased net degradation of skeletal muscles with loss of soluble, myofibrillar, and collagen proteins. Starvation for 24 hours elevated whole muscle protein breakdown in mice with and without sarcomas. Subsequent refeeding for 24 hours normalized the degradation. Adaptation to anorexia in pair-fed controls was achieved by a decrease in muscle protein turnover evaluated by urinary excretion of 3-methylhistidine over 5 days. The measurement of "catabolic decrease" of muscle protein breakdown protected the muscle mass in mice without tumors, but it was ineffective in tumor-bearing animals. The unchanged rate of breakdown of proteins in whole EDL muscles from tumor-bearing mice was accompanied by increased maximum cathepsin D activity and by elevated autolytic activity at acid pH in some muscles. Therefore, cathepsin D activity and net protease activities did not reflect whole muscle protein degradation in tumor-induced malnutrition. The results demonstrate that wasting of skeletal muscles in experimental cancer was not dependent on increased degradation but was dependent on depressed protein synthesis.

Effects of indomethacin, cytokines, and cyclosporin A on tumor growth and the subsequent development of cancer cachexia.

C57BL/6J mice bearing a low or undifferentiated rapidly growing tumor were treated daily with either i.p. injections of the recombinant cytokines interleukin(IL)-1 alpha, IL-1 beta (21 ng/g), and tumor necrosis factor alpha (21 ng/g) or s.c. injections of cyclosporin A (60 micrograms/g) or indomethacin (1 micrograms/g). In some experiments, indomethacin was administered in the drinking water corresponding to the amount of s.c. injections. Survival and the time course of tumor growth and food and water intake were measured. The nutritional state (body composition) of the animals was registered at spontaneous death in the course of tumor disease. Indomethacin prolonged survival from 14 +/- 1 to 22 +/- 1 days in tumor-bearing mice when administered either in the drinking water or as s.c. injections. This effect, which was due to tumor growth inhibition, was equally effective irrespective of whether indomethacin was instituted on Day 1, 5, 7, or 9 following tumor implantation. Indomethacin did not inhibit tumor cell growth in vitro. Indomethacin-treated tumor-bearing mice were also less anorectic than untreated tumor-bearing mice, and their nutritional state, particularly lean body mass, was significantly improved by indomethacin at doses (1 micrograms/g) that did not influence the food intake or body composition in non-tumor-bearing mice. At spontaneous death, indomethacin-treated tumor-bearing mice had a significantly larger tumor burden when accounting for their degree of malnutrition as compared with untreated tumor bearers. Indomethacin did not decrease the elevation in hepatic concentrations of RNA seen in response to tumor progression. Adherent peritoneal macrophages from tumor-bearing mice had a lower prostaglandin E2 synthesis compared with macrophages from non-tumor-bearing controls in the basal state (1100 +/- 150 pg/10(6) cells versus 3700 +/- 922 pg/10(6) cells). Lipopolysaccharide stimulated macrophages from tumor-bearing mice to produce significantly more prostaglandin E2 in vitro compared with control macrophages (39,500 +/- 4208 pg/10(6) cells versus 12,500 +/- 4330 pg/10(6) cells).(ABSTRACT TRUNCATED AT 400 WORDS)

Role of whole-body lipids and nitrogen as limiting factors for survival in tumor-bearing mice with anorexia and cachexia.

This study was designed to ascertain whether the overall availability of whole-body lipids and nitrogen is a limiting factor for survival in tumor-bearing mice suffering from anorexia and cachexia. Three-month-old nongrowing mice (C57BL/6J) were given s.c. transplants of a methylcholanthrene-induced sarcoma. Freely fed, starved, and pair-fed animals were used. Body and lipid composition, tumor growth, and survival time were measured. Freely fed sarcoma-bearing mice died with profoundly altered body composition. This was not explained by the anorexia assessed in pair-feeding experiments. Starvation had caused a more severe depletion in body composition in both tumor-bearing and nontumor-bearing animals than the tumor alone did in freely fed tumor-bearing mice. Freely fed tumor-bearing animals had normal proportions of whole-body triglycerides, cholesterol, and polar lipids, but they lost palmitic acid quantitatively more than any other fatty acid. It is unlikely that any single fatty acid became limiting during tumor growth. The results show that the overall availability of lipids, nitrogen, and glucose precursors is not a limiting factor for survival in experimental tumor cachexia. Other factors considered to be more likely as determining factors for the death of tumor-bearing animals are discussed.

Cytokine and cyclooxygenase-2 protein in brain areas of tumor-bearing mice with prostanoid-related anorexia.

Evidence suggests that cytokines in the central nervous system are mediators behind anorexia in tumor-bearing hosts. We have therefore evaluated, by immunohistochemical image analyses, time course changes of interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF) alpha, IL-6 receptor (gp130), IL-1 receptor I, and cyclooxygenase (Cox)-2 protein in brain cortex, hippocampus and the ventromedial hypothalamic nucleus (VMH) in tumor-bearing mice with prostanoid-related anorexia. Pair-fed non-tumor-bearing mice were used as controls. Prostaglandin E(2) was provided systemically to freely fed, non-tumor-bearing mice to confirm a role for prostanoids in modulation of brain cytokines and food intake. Time course changes of IL-1beta were significantly different between tumor-bearing mice and pair-fed controls in the hippocampus but not in the VMH. TNF-alpha in the hippocampus and VMH did not show any significant difference between tumor-bearing mice and pair-fed controls, whereas TNF-alpha showed a small increase over time in brain VMH. IL-6 content did not show any significant alterations among tumor-bearing and pair-fed mice but increased significantly over time in both the study and control group. Cox-2 in brain hippocampus and VMH showed a statistically significant rise in both tumor-bearing and pair-fed controls, with no difference between animal groups. Systemic provision of exogenous PGE(2) to non-tumor-bearing mice altered brain cytokines significantly in the hippocampus and VMH with associated changes in food intake. Our results demonstrate that some differences (IL-1beta) occurred in brain cytokines comparing tumor-bearing and pair-fed, non-tumor-bearing mice but within unexpected decreased levels in brain tissue from tumor-bearing mice. Surprisingly, many time course changes in brain cytokines were similarly altered in tumor-bearing and pair-fed mice. Our observations do not support that up-regulation of brain cytokines explains or promotes anorexia in cancer disease. Rather, cytokine and Cox-dependent alterations in brain tissue seemed to be secondary to a decline in food intake and related to subsequent stress hormone activities.

Experimental cancer cachexia: the role of host-derived cytokines interleukin (IL)-6, IL-12, interferon-gamma, and tumor necrosis factor alpha evaluated in gene knockout, tumor-bearing mice on C57 Bl background and eicosanoid-dependent cachexia.

MCG 101 tumors were implanted sc. on wild-type C57 Bl and gene knockout mice to evaluate the role of host-produced cytokines [interleukin (IL)-6, IL-12, IFNgamma, tumor necrosis factor (TNF) receptor 1, and TNF receptor 2] to explain local tumor growth, anorexia, and carcass weight loss in a well-defined model with experimental cachexia. Indomethacin was provided in the drinking water to explore interactions between host and tumor-derived prostaglandins and proinflammatory cytokines for tumor growth. Wild-type tumor-bearing mice developed cachexia because of rapid tumor growth, which were both attenuated in IL-6 gene knockouts. Similar findings were observed after provision of anti-IL-6 to wild-type tumor-bearing mice. Alterations in food intake were not directly related to systemic IL-6 but rather secondarily to IL-6-dependent tumor growth. The absence of host-derived IL-12, IFN-gamma, or the TNF receptor 1 or receptor 2 gene did not attenuate tumor growth or improve subsequent cachexia. Thus, carcass weight loss was not improved by the omission of host cytokine (TNF-alpha, IL-12, or IFN-gamma) except for IL-6. Systemic indomethacin provision decreased plasma prostaglandin E2 in five of six groups of gene knockout tumor-bearing mice, which was associated with improved carcass weight in these groups. Indomethacin seemed to improve food intake to a similar extent in both wild-type and gene knockouts, which agree with the speculation that eicosanoids are more important to explain anorexia than host cytokines. Our results demonstrate that host- and tumor-derived cytokines and prostaglandins interact with tumor growth and promote cachexia in a more complex fashion than usually presented based on previous information in studies on either anti-cytokine experiments in vivo or on gene knockouts with respect to a "single cytokine model." Overall, host cytokines were quantitatively less important than tumor-derived cytokines to explain net tumor growth, which indirectly explains subsequent cachexia and anorexia.

Plasma protein synthesis in experimental cancer compared to paraneoplastic conditions, including monokine administration.

During tumor growth, there are characteristic alterations in the concentration and synthesis of various plasma proteins. The purpose of this study was to evaluate whether these changes are unique to a tumor-bearing state, or rather, they represent a generalized response to a paraneoplastic state mediated by the release of monokines or protein-calorie malnutrition. Plasma protein synthesis and concentrations in mice bearing a transplantable fibrosarcoma were compared to animals receiving either a terpentine abscess, Corynebacterium parvum administration, calorie-protein depletion, or administration of the recombinant-derived monokines, murine interleukin 1 alpha or human tumor necrosis factor-alpha. Tumor-bearing animals showed a significant increase in total plasma protein synthesis that was similar in magnitude to the increase seen following a terpentine abscess or after administration of interleukin 1 or tumor necrosis factor-alpha. Similarly, the pattern of protein synthesis and concentration, as determined by isoelectric focusing or sodium dodecyl sulphate-polyacrylamide gel electrophoresis, were similar, albeit not identical, among tumor-bearing animals and those receiving either a terpentine abscess, C. parvum and monokine administration. Serum amyloid P concentrations were markedly elevated in tumor-bearing animals, as they were in animals after a sterile abscess and following interleukin 1 administration, as well as to a lesser extent tumor necrosis factor-alpha administration. We can therefore conclude that the majority of changes in plasma protein concentration and synthesis seen in this tumor-bearing model are similar to those seen during an acute inflammation and can be reproduced to a large extent by the administration of the monokines, interleukin 1 alpha or tumor necrosis factor-alpha.

Energy metabolism in nongrowing mice with sarcoma.

The time course of energy metabolism has been studied in weight-stable and nongrowing mice with a transplantable methylcholanthrene-induced sarcoma. Daily oxygen consumption and carbon dioxide production were measured in relation to the tumor growth from the time of tumor implantation. The time course of energy dynamics was related to the end-state changes in body composition. Freely fed sarcoma-bearing mice decreased their whole-body energy expenditure in proportion to the tumor growth. This was due to the accompanying anorexia. The alteration in oxygen consumption and carbon dioxide production was continuously evident 24 hr/day in sarcoma-bearing mice. The tumor-bearing mice lost body fat and had decreased respiratory quotient, while pair-fed controls maintained their body composition, and their respiratory quotients agreed with the food respiratory quotient. Loss of body lipids in freely fed sarcoma-bearing mice reflected a negative energy balance, accompanied with increased fat oxidation, while maintenance of body composition in pair-fed controls reflected a decreased metabolic rate. Sarcoma-bearing mice showed a significantly higher energy expenditure in relation to their food intake compared to that of pair-fed controls. Estimates of partition of oxygen uptake in sarcoma-bearing mice support that both the host and the tumor account for the elevated energy expenditure. This study has confirmed a small but significantly increased energy expenditure in sarcoma-bearing mice, which was continuously present 24 hr/day in spite of unlimited availability of food. This illustrates the fatal outcome of experimental cancer.

Effect of cyclooxygenase and nitric oxide synthase inhibitors on tumor growth in mouse tumor models with and without cancer cachexia related to prostanoids.

The potential interaction between cyclooxygenase (Cox) and NO metabolic pathways in the control of local tumor growth was evaluated. Mice bearing either a sarcoma-derived tumor (C57B1; MCG 101) or a malignant melanoma (C3H/HeN; K1735-M2) were used. These models were principally different because they demonstrate, in tumor hosts, conditions with and without cancer cachexia, seemingly related to high and low production of prostanoids, respectively. Cox inhibitors (Cox-1 and Cox-2) decreased tumor growth by 35-40% in MCG 101-bearing mice but had no such effect on melanoma-bearing mice, despite the expression of the Cox-2 protein in melanoma cells. Indomethacin reduced prostanoid production in both tumor (MCG 101) and host tissues and reduced tumor cell proliferation, mainly in vivo. Nitric oxide synthase (NOS) inhibitors (N(omega)-nitro-L-arginine methyl ester and N(omega)-nitro-L-arginine) reduced tumor growth in vivo by approximately 50% in both tumor models. Tumor growth reduction, related to NOS inhibition, was unrelated to prostanoid production and was an in vivo phenomenon in both tumor models. Specific inhibitors of inducible NOS activity, unexpectedly, had no effect in any tumor model, although inducible NOS protein was present in tumor tissues in large amounts. A combination of Cox and NOS inhibitors had no additive effect on tumor growth (MCG 101). Cox inhibition increased tumor tissue (MCG 101) expression of cNOS mRNA but had no significant effect on tumor tissue expression of the transferrin receptor, vascular endothelial growth factor, or basic fibroblast growth factor. NOS inhibition increased tumor tissue content of cNOS mRNA but showed as well a trend to increase mRNA content of the transferrin receptor and vascular endothelial growth factor. Our results suggest that NOS inhibitors can decrease the local growth of tumors that are either responsive or unresponsive to Cox inhibition. This effect may reflect cross-talk between Cox and NOS pathways within or among tumor cells, or it may represent unrelated effects on tumor and host cells. Whether NO inhibition may be used therapeutically in clinical tumors that are unresponsive to eicosanoid intervention remains to be evaluated.

Protein synthesis in liver tissue under the influence of a methylcholanthrene-induced sarcoma in mice.

Amino acids are incorporated at increased rates into hepatic proteins in tumor-bearing humans and animals. In this study, we hoped to elucidate whether this is an expression of increased hepatic protein synthesis or altered isotope dilution in the precursor pool(s). Liver tissue from sarcoma-bearing mice (MCG 101) showed increased specific activities of arginine and leucine in hepatic proteins after i.p. injection of these precursors. The specific radioactivity of leucine in the free amino acid incorporation rate into proteins was also found in incubated liver slices and in a cell-free system of incubated free and membrane-attached polysomes. The increased amino acid incorporation was the net result of increased as well as decreased relative turnover of various hepatic proteins. The hepatic content of RNA was increased, but hepatic DNA and protein content was unchanged in tumor-influenced livers. Increased amino acid incorporation into hepatic proteins in tumor-bearing animals and also probably in cancer patients is due to a net increased hepatic protein synthesis, probably not confined to acute-phase reactants only.

Flux of amino acids across the leg in weight-losing cancer patients.

Flux of amino acids across the leg was measured in malnourished cancer patients and three control groups: (a) malnourished patients without cancer; (b) well-nourished but acutely ill patients; and (c) well-nourished controls hospitalized for minor elective surgery. All patients were examined after an overnight fast, and some patients were reexamined 2 weeks later during enteral nutrition by gastric infusion of a formula diet. The efflux of amino acids did not differ qualitatively or quantitatively between malnourished cancer patients and malnourished patients without cancer. Well-nourished patients with acute illness had the greatest release of amino acids after an overnight fast. The leg efflux of amino acids did not correlate with plasma insulin levels in any of the patient groups, either in the fasting or in the fed state. Enteral nutrition decreased the efflux of amino acids from the leg in malnourished patients without cancer, but not in the malnourished cancer group. Enteral nutrition resulted in an increased peripheral uptake of energy precursors as glucose, free fatty acids, and the branched-chain amino acids. This was concomitant with increase in plasma level of triiodothyronine in malnourished patients without cancer. This study demonstrates that malnourished cancer patients do not differ from malnourished patients without cancer or from well-nourished patients after an overnight fast with respect to amino acid efflux from peripheral tissues, and thus shows normal adaptation for protein conservation. The results also suggest that conventional nasogastric tube-feeding was not sufficient alone to support normal replenishment of peripheral tissue in malnourished patients with and without cancer.

Glucose flux in relation to energy expenditure in malnourished patients with and without cancer during periods of fasting and feeding.

Glucose dynamics, energy metabolism, and nitrogen balance were studied in eight malnourished cancer patients and seven malnourished patients without cancer. Glucose flux was measured by single injection of [6-3H]glucose and [U-14C]glucose. Energy expenditure was measured by indirect calorimetry. Each patient was studied after an overnight fast and during constant gastric infusion of a formula diet. Cancer patients had elevated glucose flux when fasting, corresponding to 42% of their spontaneous daily intake of glucose. At least one-half of the elevated flux in cancer patients compared with controls was due to increased recycling of glucose carbon after an overnight fast. Feeding doubled the total glucose flux in both cancer and control patients. The recycling was unchanged in the cancer group and disappeared in the controls during feeding. The increased glucose flux in cancer patients was concomitant with normal resting energy expenditure during periods of both fasting and feeding. Glucose flux in relation to energy expenditure was doubled in cancer patients compared to controls, and the glucose flux in fed cancer patients was similar to the rate of glucose infusion, which shows that the endogenous production of glucose was not inhibited. Cancer and control patients reached a comparable positive energy and nitrogen balance, allowing for their overall caloric intake. Our results show that cancer patients seem to have a characteristically increased glucose demand, which contributes to their weight loss when fasting. The energy drain by this elevated glucose flux can explain, as a maximum estimate, a loss of about 0.9 kg of body fat per 30-day period.

Reutilization of amino acid carbons in relation to albumin turnover in nongrowing mice with sarcoma.

Reutilization of amino acid carbons was evaluated in relation to increased turnover of albumin in tumor-bearing mice. A methylcholanthrene-induced sarcoma (MCG 101) was used in nongrowing mice (C57BL/6J). Sarcoma-bearing mice developed hypoalbuminemia, but pair-fed controls did not. The hypoalbuminemia was caused by increased albumin degradation rate, measured by injection of Na214CO3, and by exponentially increased deposition of albumin into the tumor compartment. The fractional synthesis rate of albumin was doubled in tumor-bearing mice compared with controls. The translational capacity of albumin synthesis evaluated in vitro was maintained in tumor host livers. The recycling of [14C]leucine carbons was almost extinguished in plasma albumin of sarcoma-bearing mice, while that of control mice contributed to 30 to 40% of the total leucine carbon flux in turned over albumin. The recycling of arginine carbons was also different when measured after simultaneous injection of [guanido-14C]arginine and [2,3-3H]arginine. The hepatic pool of free leucine was increased by 22% in tumor-bearing mice. It is concluded that increased albumin degradation in cancer may be a disordered event and is earlier and of initially greater quantitative importance than is altered synthesis of albumin for the development of hypoalbuminemia in experimental cancer.