Buffalo Rats Research Articles

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.

Herpes Simplex Virus (HSV)-Mediated ICAM-1 Gene Transfer Abrogates Tumorigenicity and Induces Anti-Tumor Immunity

Costimulatory and cellular adhesion molecules are thought to be essential components of antigen presentation in the immune response to cancer. The current studies examine gene transfer utilizing herpes viral amplicon vectors (HSV) to direct surface expression of adhesion molecules, and specifically evaluate the potential of a tumor-expressing intercellular adhesion molecule-1 (ICAM-1) to elicit an anti-tumor response. The human ICAM-1 (hICAM1) gene was inserted into an HSV amplicon vector and tested in a transplantable rat hepatocellular carcinoma and in a human colorectal cancer cell line. Cell surface ICAM-1 expression was assessed by flow cytometry. Lymphocyte binding to HSV-hICAM1-transduced cells was compared with that to cells transduced with HSV not carrying the ICAM gene. Tumorigenicity of HSV-hICAM1-transduced tumor cells were tested in syngeneic Buffalo rats. Additionally, immunization with irradiated (10,000 rads) HSV-hICAM1-transduced tumor cells was performed to determine its effect on tumor growth. A 20-min exposure of tumor cells at a multiplicity of infection (MOI) of 1 resulted in high-level cell surface expression of human ICAM in approximately 25% of tumor cells. Transduced rat or human tumor cells exhibited significantly enhanced binding of lymphocytes (p < 0.05). HSV-hICAM1-transduced cells elicited an increase in infiltration by CD4(+) lymphocytes in vivo and exhibited decreased tumorigenicity. Immunization with irradiated HSV-hICAM1-transduced cells protected against growth of subsequent injected parental tumor cells. HSV amplicon-mediated gene transfer is an efficient method for modifying the cell surface expression of adhesion molecules. Increased tumor expression of ICAM-1 represents a promising immune anti-cancer strategy.

Oncolytic viral therapy for human colorectal cancer and liver metastases using a multi-mutated herpes simplex virus type-1 (G207).

G207 is a multi-mutated, replication-competent type-1 herpes simplex virus designed to target, infect, and lyse neurological tumors. This study examines the feasibility of using G207 in the treatment of human colorectal cancer and defines the biological determinants of its antitumor efficacy. This virus was tested on five human colorectal cancer cell lines in vitro to determine efficacy of infection and tumor cell kill. These results were correlated to measures of tumor cell proliferation. In vivo testing was performed through direct injections of G207 into xenografts of human colorectal cancer tumors grown in flanks of athymic rats. To evaluate an alternate method of administration, hepatic portal vein infusion of G207 was performed in a syngeneic model of liver metastases in Buffalo rats. Among the five cell lines tested, infection rates ranged between 10% and 90%, which correlated directly with S-phase fraction (8.6%-36.6%) and was proportional to response to G207 therapy in vitro (1%-93%). Direct injection of G207 into nude rat flank tumors suppressed tumor growth significantly vs. control (0.58 +/- 0.60 cm(3) vs. 9.16 +/- 3.70 cm(3), P<0. 0001). In vivo tumor suppression correlated with in vitro effect. In the syngeneic liver tumor model, portal infusion resulted in significant reduction in number of liver nodules (13 +/- 10 nodules in G207-treated livers vs. 80 +/- 30 nodules in control livers, P<0.05). G207 infects and kills human colorectal cancer cells efficiently. In vitro cytotoxicity assay and tumor S-phase fraction can be used to predict response to treatment in vivo. This antineoplastic agent can be delivered effectively by both direct tumor injection and regional vascular infusion. G207 should be investigated further as therapy for colorectal cancer and liver metastases.

FK506 accelerates functional recovery following nerve grafting in a rat model.

The sometimes dramatic and permanent functional deficits that result from severe peripheral nerve injuries provide compelling incentives to identify exogenous agents that may expedite axonal regrowth and avoid prolonged denervation of end organs. The purpose of this study was to identify, whether the regular systemic administration of tacrolimus (FK506) or cyclosporin A (CsA) would influence the speed and efficiency of nerve regeneration through short nerve grafts. A total of 35 Buffalo rats each received a 2-cm posterior tibial nerve graft and were randomized to one of three experimental groups. Group I animals were left untreated, group II received daily CsA (5 mg/kg intraperitoneally), and group III received daily FK506 (1 mg/kg intraperitoneally). Walking tracks were obtained starting 3 weeks after graft placement and continuing biweekly for the next 7 weeks. FK506-treated animals fully recovered hindlimb function 7 days earlier than CsA-treated animals or untreated control animals. Regenerated nerves from one-half of each treatment group were harvested for histomorphometric analysis at 7 weeks, shortly after recovery was complete in the FK506-treatment group but not in the other two groups, and once again at 10.5 weeks when recovery of function had stabilized in all groups. At 7 weeks, FK506-treated animals had significantly greater fiber density and percentage of neural tissue per nerve and a significantly larger population of mature, myelinated fibers in comparison with either CsA-treated or untreated animals. The authors concluded that the daily, systemic administration of low-dose FK506 facilitates peripheral nerve recovery and regeneration after nerve grafting.

KINETIC ANALYSIS OF DONOR-SPECIFIC TOLERANCE BY NONDEPLETING ANTI-CD4 MONOCLONAL ANTIBODY (RIB 5/2) PLUS DONOR ALLOANTIGEN

62 Background: A single dose of RIB 5/2 plus donor splenocytes (SC) results in donor specific unresponsiveness to heart and kidney allografts. This study analyzes the kinetics of the development and persistence of this tolerance. Methods: A single intraperitoneal (IP) dose of 20 mg/kg RIB 5/2 + IV Lewis (RT11) SC (25×106) were injected into Buffalo rats (RT1b) and a MHC mismatched donor specific LEW or 3rd party Brown Norway (RT1n) kidney was transplanted at day 0, 21, or 40. In some animals transplanted at day 40, a second dose of LEW SC was given at day 21 (Gp 4). A second LEW or BN heart tested specificity. Mixed lymphocyte cultures (MLC) and cytotoxicity (CTL) were performed before transplantation on day 0, 21 and 40 after pretreatment. Results: Donor specific LEW (Gp 2a), but not 3rd party BN kidneys (Gp 2b), transplanted at day 21 were accepted indefinitely. However, both BN (Gp 1c and 1d) and LEW (Gp 1a and 1b) kidneys were accepted at day 0 (Gp 1), while LEW kidneys transplanted on day 40 were acutely rejected (Gp 3). In contrast, additional LEW SC given on day 21 prevented rejection of day 40 LEW transplants (Gp 4). Unresponsiveness to a 40-day, 2nd heart transplant in Gp 1 was specific to the 1st transplant but not to alloantigen given on day 0 (Gp 1a-1d). (Table 1)TableIn vitro assays also showed no donor specific suppression of MLC and CTL at day 0, but specific suppression at day 21 and full recovery of response by day 40. (Table 2)TableConclusion: The period of donor specific unresponsiveness and allograft acceptance induced by RIB 5/2 MoAb + donor alloantigen spontaneously reverses, unless donor specific allograft is present, or splenocyte antigen is re-presented.

Effect of amaranth and oat bran on blood serum and liver lipids in rats depending on the kind of dietary fats.

The effect of amaranth and oat bran on the lipids of blood and liver in rats depending on the kind of fats in diet was the subject of our study. Sixty male Buffalo rats were fed for 28 days one of six diet containing 15% of fat (lard or sunflower oil), 20% of protein and 0.5% of cholesterol. Amaranth and oat bran added to diet provided 4-4.5% of dietary fiber, water soluble fraction of which amounted to 30%. Amaranth significantly decreased the level of total cholesterol in rats blood serum (by 10.7% in the case of diet with lard and by 14% with sunflower oil) and in liver (by 20% in the case of diet with lard and by 23% with sunflower oil). Similarly oat bran decreased the level of total cholesterol in the blood serum: by 19% in the case of diet with lard and by 22% with sunflower oil; and in liver by 22 and 27%, respectively. Amaranth and oat bran did not influence HDL-cholesterol in the blood of rats. The influence of amaranth and oat bran on the concentration of triglycerides in the blood serum depended on the kind of fats in a diet. The diets containing amaranth or oat bran with lard did not decrease the concentration of this lipids, however, the same diets but with sunflower oil decreased this concentration significantly (by 22%). In liver significant hypotriglyceridemic effect of amaranth and oat bran was observed for both of the diets: based on lard and sunflower. The decrease of triglycerides concentration under the influence of amaranth amounted to 10% (diet with lard) and 15% (diet with sunflower oil). Oat bran decreased the concentration of triglycerides in liver by 15% (diet with lard) and 20% (diet with sunflower oil). Sunflower oil added to the diets augmented the hypolipemic effect of amaranth and oat bran.

Enhanced cellular immunity to hepatitis C virus nonstructural proteins by codelivery of granulocyte macrophage-colony stimulating factor gene in intramuscular DNA immunization

Hepatitis C virus (HCV) nonstructural (NS) proteins appeared to be important targets for HCV vaccine development, since NS-specific T-helper-cell responses are associated with clearance from acute HCV infection. In this report, we have constructed a plasmid, pTV–NS345, that encodes the HCV NS3, NS4 and NS5 proteins (NS345) and a bicistronic plasmid, PTV–NS345/GMCSF, in which the HCV NS345 polyprotein and GMCSF are translated independently. Intramuscular inoculation with pTV–NS345 plasmid DNA into the Buffalo rats generated both antibody and T-cell proliferative responses to each NS protein. The expression of GMCSF, together with HCV NS345 proteins, appeared to significantly increase T-cell proliferative responses. In particular, the inoculation of a bicistronic plasmid generated higher T-cell proliferative responses to each NS protein than did the coinjection of two separate plasmids, pTV–NS345 and pTV-GMCSF. These results demonstrate that the codelivery of GMCSF augmented HCV NS345-specific cellular immunity and that the intensity of the immunity was differed depending on how GMCSF gene is codelivered.

Wax D of Mycobacterium tuberculosis induced osteomyelitis accompanied by reactive bone formation in Buffalo rats

A suspension of heat-killed Mycobacterium tuberculosis in liquid paraffin has been reported to induce foot swelling accompanied by new bone formation in Buffalo (BUF) rats, which are low responders to the induction of adjuvant arthritis. In the present study, we found that wax D, a mycobacterial cell wall peptidoglycan fragment-arabinogalactan-mycolic acid complex, was an effective component of this bacterium for the induction of osteomyelitis accompanied by reactive bone formation in BUF rats. Chronic inflammation was produced in BUF rats by a single subcutaneous injection of wax D suspended in liquid paraffin. Other Mycobacterium species and Gordona bronchialis were also capable of inducing this reaction. Other bacterial cells including the acid-fast bacteria Nocardia and Rhodococcus, purified cell walls and peptidoglycans from Lactobacillus plantarum, wax C, cord factor, arabinogalactan and mycolic acid prepared from M. tuberculosis were inactive in this respect. In addition, when wax D was administered as a water-in-oil emulsion (Freund's type adjuvant), bone formation scarcely occurred in BUF rats. In Fisher (F344) and Wistar rats, both of which are responder strains to adjuvant arthritis, wax D in liquid paraffin did not induce bone formation.

Wax D of Mycobacterium tuberculosis induced osteomyelitis accompanied by reactive bone formation in Buffalo rats.

A suspension of heat-killed Mycobacterium tuberculosis in liquid paraffin has been reported to induce foot swelling accompanied by new bone formation in Buffalo (BUF) rats, which are low responders to the induction of adjuvant arthritis. In the present study, we found that wax D, a mycobacterial cell wall peptidoglycan fragment-arabinogalactan-mycolic acid complex, was an effective component of this bacterium for the induction of osteomyelitis accompanied by reactive bone formation in BUF rats. Chronic inflammation was produced in BUF rats by a single subcutaneous injection of wax D suspended in liquid paraffin. Other Mycobacterium species and Gordona bronchialis were also capable of inducing this reaction. Other bacterial cells including the acid-fast bacteria Nocardia and Rhodococcus, purified cell walls and peptidoglycans from Lactobacillus plantarum, wax C, cord factor, arabinogalactan and mycolic acid prepared from M. tuberculosis were inactive in this respect. In addition, when wax D was administered as a water-in-oil emulsion (Freund's type adjuvant), bone formation scarcely occurred in BUF rats. In Fisher (F344) and Wistar rats, both of which are responder strains to adjuvant arthritis, wax D in liquid paraffin did not induce bone formation.

Optimal induction of hepatitis C virus envelope-specific immunity by bicistronic plasmid DNA inoculation with the granulocyte-macrophage colony-stimulating factor gene.

In this study, we have constructed various DNA vaccine vectors that carried hepatitis C virus (HCV) envelope genes without and with the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene in several different ways. In Buffalo rats that received plasmids carrying the HCV envelope genes, which encode envelope proteins E1 and E2, both antibody and lymphoproliferative responses against these proteins were induced. These responses were greatly enhanced by the codelivery of the GM-CSF gene. In particular, inoculation with a bicistronic plasmid that independently expressed the GM-CSF gene and the envelope genes in the same construct generated the highest antibody titers and significantly increased lymphoproliferative responses against these proteins. Moreover, strong antibody responses to homologous and heterologous hypervariable region 1 peptides were elicited in the immunized rats.

Induction of donor-specific tolerance to rat nerve allografts with portal venous donor alloantigen and anti-ICAM-1/LFA-1 monoclonal antibodies

Background: Expendable autologous nerve available for repair of nerve injuries is limited. Cadaveric allografts could provide adequate nerve for grafting but are susceptible to rejection and currently require chronic systemic immunosuppression. Methods: Age-matched Buffalo (RT1 b) rats randomly assigned to 7 experimental groups received either a Lewis (RT1 l) rat posterior tibial-sciatic nerve allograft or a Buffalo (RT1 b) syngeneic isograft. Recipients were treated with anti-intercellular adhesion molecule-1 (anti-ICAM-1) and anti-leukocyte function-associated antigen-1 (anti-LFA-1) monoclonal antibodies (mAbs), intraportally administered ultraviolet B (UVB)-irradiated donor splenocytes, a combination of mAbs and UVB-irradiated donor splenocytes, or no immunosuppression. Results: Histologic, electrophysiologic, and functional evaluation of nerve allografts 8 weeks after transplantation revealed a synergistic improvement in nerve allograft regeneration when monoclonal antibodies were combined with UVB-irradiated donor splenocytes. In vitro immunologic assessment correlated with the in vivo allograft function by demonstrating a donor-specific suppression of the recipient's response in mixed lymphocyte culture (MLC), cytotoxic T lymphocyte assay (CTL), and reduced T cell interleukin-2 production in both the group receiving UVB-irradiated alloantigen alone and the group receiving a combination of UVB antigen and mAbs. Conclusions: The combined use of mAbs directed against ICAM-1 and LFA-1 adhesion molecules with intraportally administered UVB modified donor antigen prevents nerve allograft rejection and synergistically improves nerve regeneration. (Surgery 1998;124:448-56.)

Genetic determinant and environmental carcinogens

2-Amino-1-methyl-6-phenylimidazo[4,5- b]pyridine (PhIP) is the most abundant mutagenic heterocyclic amine (HCA) present in cooked foods. PhIP induces colon cancer in male Fischer 344 (F344) rats, and its role in human colon carcinogenesis has been suspected. To study the ecogenetics in PhIP colon carcinogenesis, rat system using aberrant crypt focus (ACF) formation as a phenotypic marker was applied. Among Buffalo (BUF), Brown Norway (BN), F344 and ACI/N (ACI) strains of rats, F344 rats produced a lower level of PhIP-DNA adducts than other three strains, and the number of ACFs/rat was highest in BUF, intermediate in BN and F344 and lowest in ACI. Thus there was no correlation between adduct levels and number of ACF induced by PhIP. F1 progenies of BUF and ACI developed ACF at a similar level to that of F344, and F1 progenies of F344 and ACI developed ACF at a similar level to that of F344. Thus it was indicated that susceptibility of F344 to the ACF induction was autosomally dominant over ACI rats. The results also suggest that BUF rats have at least two genes, one is autosomally recessive against ACI rats and one is autosomally dominant similar to that F344 has. A total of 170 progeny of ACI backcross of F344/ACI F 1 were examined for number of ACFs and 65 progeny were phenotyped as F344 and 60 were ACI. Using these 125 rats, chromosomal mapping is being performed using markers of simple sequence length polymorphism (SSLP) and representational difference analysis (RDA). By mapping the gene, we will be able to identify humans who might belong to high risk group in general population, and cancer can be prevented more efficiently by attaining early diagnosis.

DONOR-SPECIFIC TOLERANCE BY PERIOPERATIVE INTRATHYMIC INJECTION OF BONE MARROW CELLS IN THE RAT CARDIAC ALLOGRAFT MODEL

Many strategies of tolerance induction by intrathymic (IT) injection of donor alloantigens have been reported to date; however, the timing of IT injection is usually 1-3 weeks before transplantation. To apply IT injection to cadaveric organ transplantation, 1 x 10(8) fully allogeneic bone marrow cells (BMC) of Buffalo (BUF; RT1b) rats were intrathymically injected into Wistar Furth (WF; RT1u) rats at the time of BUF cardiac allografting with short-course therapy of antilymphocyte serum (ALS) and FK506 in our experimental model. Allogeneic IT injection of BUF BMC with ALS and FK506 indefinitely prolonged graft survival (mean survival time > 210 days) in all WF rats. On day 130 after grafting, tolerant WF rats accepted donor BUF skin grafts (> 120 days) but not third-party Lewis skin grafts. In control groups, syngeneic IT injection of WF BMC or intravenous injection of donor BUF BMC in combination with ALS/FK506 therapy failed to induce tolerance. In vivo testing was performed during induction (1 month) or during maintenance (6 months of tolerance. In the mixed lymphocyte reaction (MLR), spleen T cells of tolerant rats at 1 month after grafting displayed hyporesponsiveness after stimulation with donor cells. The addition of interleukin (IL)-2 to MLR culture did not restore T-cell responsiveness. Tolerant rats had a significantly decreased frequency of T cytotoxic cell precursors (fTcp) of 1:4,926, and frequency of IL-2-producing T helper cell precursors (fThp) of 1:23,925, compared with naive rats (1: 2,158 and 1:4,266, respectively). By 6 months after grafting, however, the anti-donor MLR proliferative responses of tolerant rats had been restored to the levels of naive splenic T cells. These tolerant rats displayed restoration of the (fTcp) of 1:2,842 and of the (fThp) of 1:5,630, which were comparable frequencies of naive rats. Suppressor T cells did not contribute in this model. In cardiac grafts of tolerant rats induced by IT injection, expression of both Th1 (interferon-gamma and IL-2) and Th2 (IL-4 and IL-10) cytokines was detected in the early phase; thereafter, expression was completely inhibited, except for interferon-gamma in the chronic phase. Perfect donor-specific tolerance was obtained by IT injection of donor BMC at the time of transplantation, while alloimmune responses were maintained at levels similar to those of naive rats.

Dietary Linoleic Acid Intake Controls the Arterial Blood Plasma Concentration and the Rates of Growth and Linoleic Acid Uptake and Metabolism in Hepatoma 7288CTC in Buffalo Rats ,

In this study, we tested the hypothesis that dietary linoleic acid intake controls the arterial blood plasma linoleic acid concentration and the rates of tumor growth and linoleic acid metabolism in vivo. Seven groups of young male Buffalo rats (11–21 rats/group) were given free access to semipurified diets containing different amounts of corn and/or olive oils. Four other groups (7–11 rats/group) were 30% energy-restricted. Each experiment included periods for rat growth and plasma lipid stabilization (6 wk), measurement of mean daily arterial blood plasma fatty acid concentrations (3 wk), surgical implantation of a subcutaneous tissue-isolated hepatoma 7288CTC, tumor growth and harvest (2–4 wk). Linoleic + arachidonic acid (P = 0.007) and oleic acid (P = 0.002) concentrations in arterial blood plasma were increased as dietary intake of linoleic and oleic acids was increased, respectively. In rats given free access to food, tumor growth was directly dependent on the plasma concentrations of linoleic (P < 0.001) and arachidonic acids (P = 0.04). Tumor growth in energy-restricted rats was dependent only on the linoleic acid concentration (P = 0.008). Energy restriction itself caused a growth inhibition independent of plasma linoleic acid. The linoleic acid and total fatty acid concentrations of tumor triacylglycerols were directly dependent on the plasma linoleic acid concentration in rats given free access to food (P = 0.009). Hepatoma 7288CTC (both in vivo and during perfusion in situ) supported a dose-dependent conversion (P < 0.001) of plasma linoleic acid to the mitogen, 13-hydroxy-9,11-octadecadienoic acid. We conclude that increased arterial blood plasma linoleic acid concentrations, caused by increased dietary intakes, specifically stimulate growth, lipid storage and linoleic acid metabolism in hepatoma 7288CTC in vivo.

Strain differences in the induction of intestinal metaplasia by X-irradiation in rats.

Strain differences in the susceptibility of rats to induction of intestinal metaplasia by X-irradiation were examined. The gastric regions of 5-week-old males of five inbred strains of rats (F344/NSlc, Copenhagen, Buffalo/NacJcl, and ACI/NHos) and three strains of randomly bred rats (HOS:Donryu, Slc:Wistar, Slc:SD) were irradiated with a total dose of 20 Gy X-ray given in two equal fractions at 3-day interrals. When examined after the rats were killed, 6 months after the last irradiation, the number of intestinal metaplastic crypts positive for alkaline phosphatase (ALP) was highest in the Donryu and lowest in the Copenhagen rats. Morphologically, the number of crypts with intestinal metaplasia in the glandular stomachs of Donryu, Wistar, SD, and Buffalo rats was higher than the number in ACI, F344, and Copenhagen rats. Intestinal metaplasia was more frequently observed in the pyloric than in the fundic glands. These results demonstrate that the induction of intestinal metaplasia by X-irradiation in rats is greatly influenced by the rat strain.

Rough-and-Tumble Play Behavior in Fischer-344 and Buffalo Rats: Effects of Social Isolation

Siviy, S. M., C. N. Baliko and K. S. Bowers. Rough-and-tumble play behavior in Fischer-344 and Buffalo rats: Effects of social isolation. Physiol Behav 61(4) 597–602, 1997.—Play behavior was assessed in two inbred strains of rats. Rats of the Fischer-344 strain (F344) were found to be less playful than Buffalo rats after social isolation, as evident from fewer pins and fewer playful attacks to the nape. When tested in same-strain pairings, overall defense of the nape did not differ between strains, although there were strain differences in the specific pattern of defense. When tested in cross-strain pairings, F344 rats were less likely to direct nape attacks toward a Buffalo play partner, and were also less likely to defend their nape when attacked by Buffalo rats. Although different levels of pinning and nape attacks in the two strains were dependent on the amount of isolation prior to the play period, differences in nape defense were not dependent on prior isolation. This pattern of results suggests that the neural mechanisms for playful attack differ from those underlying playful defense. These data also suggest that the F344 strain could be useful in better understanding the neural and genetic bases of mammalian playfulness.

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 μmol/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.

Assessment of the biodistribution and metabolism of 5-fluorouracil as monitored by 18F PET and 19F MRI: A comparative animal study

The effective clinical use of the anticancer drug 5-fluorouracil (5-FU) requires the noninvasive assessment of its transport and metabolism, particularly in the tumor and the liver, where the drug is catabolized to α-fluoro-β-alanine (FBAL). In this study, the potentials and limitations of dynamic 18F PET and metabolic 19F MRI examinations for noninvasive 5-FU monitoring were investigated in ACI and Buffalo rats with transplanted MH3924A and TC5123 Morris hepatomas, respectively. Selective 5-[ 19F]FU and [ 19F]FBAL MR images were acquired 5 and 70 min after 5-FU injection using a CHESS MRI sequence. After administration of 5-[ 18F]FU, the kinetics of the regional 5-[ 18F]FU uptake were measured by dynamic PET scanning over 120 min. To allow a comparison between PET and MRI data, standardized uptake values (SUV) were computed at the same points in time. The TC5123 hepatoma showed a significantly ( p < 0.002) higher mean SUV at 5 and 70 min post-5-FU injection than the MH3924A cell lines, whereas there were no significant differences between the mean SUV measured in the liver of both animal populations. In contrast to the PET data, no significant differences in the mean 5-[ 19F]FU and [ 19F]FBAL MR signal values in the tumor of both models were observed. The MR images, however, yielded the additional information that 5-FU is converted to FBAL only in the liver and not in the hepatomas.

Interferon gamma protects against hepatic tumor growth in rats by increasing Kupffer cell tumoricidal activity.

An increasing number of hepatic resections are being performed as potentially curative surgery for malignant liver neoplasms. Hepatectomy and subsequent liver regeneration produce a local environment that enhances growth of microscopic residual tumor. To determine if pretreatment with murine interferon gamma (IFN-gamma) can protect against such enhanced tumor growth, Buffalo rats were randomized to receive a 3-day treatment of IFN-gamma (50,000 U/qD intraperitoneally) or saline. Groups then underwent intrasplenic injection of 10(6) Morris hepatoma cells, followed 1 hour later by sham (control) or partial hepatectomy (PH) of 70%. PH significantly enhanced tumor growth within the liver (control, 8 +/- 3 nodules per liver; PH, 73 +/- 12 nodules per liver; P < .001). This enhancement was attenuated by prior administration of IFN-gamma IFN-gamma/PH, 16 +/- 3; P < .001 vs. PH). Growth factor release and liver regeneration were not affected significantly by pretreatment with IFN-gamma. The effect of IFN-gamma on tumor growth is associated with a significant enhancement of Kupffer cell (KC)-mediated tumoricidal activity (percentage of specific lysis, 55 +/- 10% control, 78 +/- 11% IFN-gamma, P < .01) but not lymphocyte-mediated tumoricidal activity. Because microscopic residual disease may be present after hepatectomies for cancer, IFN-gamma may be useful agent in retarding growth of residual tumors.