Cytochalasin-B-induced immunosuppression of murine allogeneic anti-tumor response and the effect of recombinant human interleukin-2

Summary Cytochalasin B (CB), administered i.p. to C57B1/6 mice in a single dose as a suspension in carboxymethylcellulose 2%/Tween 20 1%, inhibits in a dose-dependent and time-dependent manner the ability of spleen cells to respond to allogeneic P815 mastocytoma tumor cells in vitro. Spleen cells from CB-treated animals sensitized to X-irradiated P815 cells in 4-day cultures at a 50 : 1 responder: stimulator ratio and tested for specific cytotoxicity against⁵¹Cr-labelled P815 target cells showed strong inhibition 3 h after CB treatment at a dose of 50 mg/kg. A dose of 25 mg/kg showed measureable but not statistically significant inhibition at 3 h, whereas 10 mg/kg produced only slight inhibition, and 5 mg/kg and 2 mg/kg were non-inhibitory. None of the doses produced significant suppression 19 h or 72 h after CB treatment. Addition to the sensitization cultures of human recombinant interleukin-2 (rhIL-2) at 350 BRMP units/ml completely restored tumor lytic capacity. C57B1/1 mice treated with CB 50 mg/kg, i.p. and challenged i.p. with 3 × 10⁷ allogeneic P815 mastocytoma cells showed a brief, time-dependent, statistically significant abrogation of allogeneic responsiveness consistent with transient reversible immunosuppression within 3–12 h following CB treatment. No such inhibition of host allogeneic responsiveness in vivo was observed when CB was administered 24 h prior to, simultaneously with, or 1, 2, or 4 days after tumor challenge. Thus CB at the highest tolerated i. p. dose in vivo causes only a transient inhibition of anti-allo-responsiveness measured in culture, and rhIL-2 used in vitro restores lytic capacity. The anti-allo effect of CB is also seen to be transient directly in vivo since allogeneic tumor outgrowth is permitted for only a brief period following administration of CB. These results indicate that the use of CB in vivo in anti-tumor chemotherapy protocols will not be complicated by profound or prolonged immunosuppressive effects.Supported by the Stella Hardeman Memorial Grant for Cancer Research to the American Cancer Society and by the Liposome Company, Princeton, New Jersey, USA     

Effects of 6-keto-prostaglandin E1 on ascitic hepatoma-130 in vivo comparison with chemotherapeutic agents

The inhibitory effect of 6-keto-prostaglandin E1 (pGE1) on the growth and survival of ascitic hepatoma (AH-130) cells in vivo was compared with currently used chemotherapeutic agents. Three days after receiving an intraperitoneal injection of 3 X 10(6) AH-130 tumor cells, Donrhyu rats were injected intravenously or intraperitoneally with one of the following: Thromboxane B2 (TXB2) (0.5 mg/kg), 6-keto-pGE1 (0.5 mg/kg), Mitomycin C (MMC) (1.5 mg/kg), or MMC + 6-keto-pGE1 (1.5 mg/kg + 0.5 mg/kg). The mean survival time, median survival time, and increase of life survival percent (ILS%) during a 60 day period revealed that both 6-keto-pGE1 and 6-keto-pGE1 + MMC significantly inhibited AH-130 tumor cell growth, while TXB2 promoted tumor cell growth. We conclude that 6-keto-pGE1 like anti-tumor agents such as MMC, Diketocoriolin B, Carbazilquinon, Endoxan, and 5-Fluorouracil, can significantly inhibit growth of AH-130 tumor cells in vivo, particularly when administered in combination with the anti-tumor agent MMC.     

Chemoprotective effects of recombinant human IL-1 alpha in cyclophosphamide-treated normal and tumor-bearing mice. Protection from acute toxicity, hematologic effects, development of late mortality, and enhanced therapeutic efficacy

In this study, recombinant human IL-1 alpha (rhIL-1 alpha) was used to protect normal and tumor-bearing BALB/c mice from the acute toxicity caused by lethal doses of cyclophosphamide (Cy) and 5-fluorouracil. Pretreatment of mice for 7 days with 10,000 U/day of rhIL-1 alpha protected 70 to 100% of mice from the acute death induced by lethal doses of both Cy (380 mg/kg) and 5-fluorouracil (250 mg/kg). In contrast, post-treatment of mice with single or multiple doses of rhIL-1 alpha was not chemoprotective. Pretreatment of mice with rhIL-1 alpha increased the acute LD90 of Cy from 380 mg/kg to greater than 500 mg/kg in normal mice, an LD90 dose-modifying effect of at least 1.25, was accompanied by a more rapid recovery from neutropenia and a less severe reduction in the number of bone marrow single lineage monocyte, myeloid, or myelomonocytic colonies. Some of the mice (10 to 50%) that were successfully protected by pretreatment with rhIL-1 alpha died after day 50. These mice consistently presented with extensive pulmonary inflammation and fibrosis at death. Mice bearing murine renal cancer (Renca) were also protected from the acute toxic effects of Cy (450 mg/kg) by pretreatment with rhIL-1 alpha. Renca-bearing mice pretreated with rhIL-1 alpha and either sublethal (300 mg/kg) or lethal (450 mg/kg) doses of Cy exhibited enhanced survival times over those of untreated Renca-bearing mice. Interestingly, the cause of death in Renca-bearing mice that ultimately failed treatment with rhIL-1 alpha plus 300 mg/kg Cy was recurrent tumor, whereas most mice treated with rhIL-1 alpha plus 450 mg/kg Cy had no detectable tumor, although several died from late pulmonary inflammation and fibrosis. Thus, the dose escalation of Cy in rhIL-1 alpha-pretreated mice results in greater antitumor effects of Cy. However, the dose escalation of some cytotoxic agents allowed by the use of myelostimulatory agents can result in late fatal complications not detected in acute toxicity testing.     

Doxorubicin plus tumor necrosis factor α combination treatments in EL4-lymphoma-bearing C57BL/6 mice

 The therapeutic efficacy of a total of 42 single-agent or combination protocols involving doxorubicin (Adriamycin, ADM) and tumor necrosis factor α (TNFα) were evaluated in the syngeneic murine lymphoma model, C57BL/6-EL4. Combination treatments were the most effective and the therapeutic effects were schedule-dependent; e.g. it was generally advantageous for ADM to precede TNFα administration. Two protocols selected for further study were 4 mg/kg ADM i.v. on days 1 and 8 plus TNFα, i.v., at either 16 000 U (7 μg)/injection, on days 1 and 8 or 4000 U (1.7 μg)/injection, on days 11–15. Survival of mice bearing one of four EL4 sublines having different in vitro drug sensitivities was assessed. These sublines were E10 (ADM-sensitive/TNFα-resistant), E16 (sensitive/sensitive), ER2 (ADM-resistant/TNFα-sensitive) and ER13 (resistant/resistant). Between 80% and 100% long-term survivors (i.e. tumor free on day 60) were obtained with the two treatments in mice bearing ADM-sensitive sublines, even though one of these sublines, E10, was resistant to TNFα in vitro. Induction of long-term survival appeared, therefore, to correlate with in vitro defined sensitivity/resistance to ADM, but not to TNFα. Treatment-induced modulations of tumoricidal immune effector functions were also examined. Taken together, the results indicated that induction of long-term survival involved complex interactions of: (1) ADM-induced tumor modifications, including, but not limited to, tumor debulking, (2) combination-treatment-induced modifications of splenic cytolytic T cell and macrophage activities, and (3) the restoration of thymus cellularity. Finally, when long-term survivors resulting from treatment of E10- or E16-bearing mice were implanted with ER2 on day 120, the majority survived, indicating that long-term immune memory, capable of recognizing drug resistant variants, had been established. Received: 14 August 1997 / Accepted: 2 October 1997     

Immunotherapy of established murine B cell lymphoma. Combination of idiotype immunization and cyclophosphamide

A murine B cell lymphoma (38C13) was used to study the efficacy of idiotype immunotherapy against established tumors. Immunization of mice with 38C13 tumor-derived Ig, administered after a lethal tumor inoculation, significantly prolonged survival of animals compared to control groups. The efficacy of active immunotherapy was dramatically enhanced when combined with chemotherapy. Cyclophosphamide (100 mg/kg), administered in combination with idiotype immunization to mice bearing 10-day-old, 1 to 2 cm diameter s.c. tumors, resulted in a significant prolongation of survival as compared with either cyclophosphamide or immunization alone and yielded approximately 50% cures. Additional studies combining active immunotherapy with surgical excision of the primary s.c. tumor nodule were less effective than combination chemoimmunotherapy, indicating that reduction of tumor burden was necessary, but not sufficient for effective treatment of established 38C13 lymphoma.     

Effect of dose schedule of vitamin E and hydroxethylruticide on intestinal toxicity induced by adriamycin

CDF1 mice receiving Adriamycin, 12 mg/kg IP develop a toxic GI mucositis. The mean survival in CDF1 mice after Adriamycin injection was found to be 6.5 +/- 2.0 weeks and could be increased by alcohol or acetate Vitamin E pretreatment (with 2 g/kg qDx7d) to 22.06 +/- 12.3 weeks or by treatment with Venoruton after Adriamycin (qDx7 with 1.5 g/kg) to 23.7 +/- 12.7 weeks. Other schedules were ineffective or harmful. The ability of Venoruton to enhance survival when given after Adriamycin encouraged us to proceed to tumor bearing mice. The maximum survival with CDF1 mice bearing 5 X 10(6) L1210 cells was 1 +/- 0.2 week which could be increased to 2.17 +/- 0.8 weeks with optimal dose Adriamycin (10 mg/kg). Optimum survival with Venoruton and a single dose of Adriamycin was 2.45 +/- 0.91 weeks with Venoruton, 1.5 g, qd X 14, and 12 mg/kg Adriamycin. Treatment of L1210 bearing mice with Adriamycin, 10 mg/kg on days 1 and 8, yielded a survival of 2.23 +/- 0.7 weeks. An equitoxic regimen of Adriamycin, 11 mg/kg on days 1 and 9, plus Venoruton, 1.5 g, qd X 14, increased survival 30% to 3.08 +/- 2.9 weeks. Venoruton is a promising agent to increase the therapeutic index of Adriamycin.     

The addition of interleukin-2 to cyclophosphamide therapy can facilitate tumor growth of B16 melanoma

The role of interleukin-2 (IL-2) on tumor growth of B16F10 melanoma cells was assessed in two sets of mice with different immune status: normal (immunocompetent) mice and immunodeficient mice. The two sets of animals were treated with cyclophosphamide (CY) or IL-2 alone or with a combined therapy of CY+IL-2. On days 6 and 10 after tumor cell injection, we evaluated the incidence of hepatic B16 melanoma metastases and the percentage of hepatic volume occupied by metastatic tissue. We observed that the CY alone (300 mg/kg, days 3 and 8 post-tumoral inoculation) significantly reduced tumor growth in all treated mice; however, CY proved more effective in normal recipients than in immunodeficient hosts. On the other hand, whereas administration of IL-2 alone (10⁵ IU daily, from day 3 to day 7) in immunocompetent mice significantly reduced tumor growth on days 6 and 10, in immunodeficient mice, no significant differences were observed in tumor growth either on the 6th or on the 10th day, in comparison to control groups. Finally, when the combined CY+IL-2 therapy was administered, an antisynergistic effect between these therapeutic agents was achieved both in normal and in immunodeficient mice. Thus, the addition of low-dose IL-2 (25×10³ IU daily, from day 4 to day 7) to high-dose CY (300 mg/kg, days 3 and 8) significantly increased tumor growth in both the early and later periods, compared to the effect of CY alone. It is concluded that exogenous IL-2 can facilitate tumor growth of B16 melanoma cells in vivo.     

Interference of anti-tumor and immunosuppressive effects of cyclophosphamide in tumor-bearing rats

Summary Adult rats were given 10⁵ or 10⁶ Yoshida ascites sarcoma (YAS) cells IP and were treated with cyclophosphamide (CY) given IP in single doses of 20 mg/kg or 100 mg/kg, 2 or 5 days after YAS inoculation. Both the curative effect of CY and subsequent resistance to tumor challenge in rats that survived depended on the dose of injected tumor cells and on the dose and time of administration of CY. These three factors determined whether the host's immune response to tumor antigens would develop and contribute to the overall anti-tumor effects of the chemotherapy. The curative effects of CY were significantly less pronounced in T-cell-deficient than in normal rats. Anti-tumor and immunosuppressive activities of CY exerted opposite influences on the ultimate result of the chemotherapy. Adverse immunosuppressive effects prevailed when the drug was administered early (2 days) after YAS inoculation. In this case the chemotherapy was less efficient and the surviving rats were susceptible to a subsequent tumor challenge. Further analysis showed that the injection of CY 2 days after inoculation of YAS antigens induced strong and specific immunologic tolerance to the tumor. In contrast, when a sufficient amount of tumor antigens (higher dose of tumor cells injected and CY injection delayed) elicited an anti-YAS immune response that was not suppressed by early injection of CY (CY administered 5 days after the tumor) effective eradication of tumor cells and anti-YAS resistance in cured animals were observed.Abbreviations YAS Yoshida ascites sarcoma - CY cyclophosphamide - MRBC mouse red blood cells     

Radiosensitization by gemcitabine fixed-dose-rate infusion versus bolus injection in a pancreatic cancer model

It has recently been shown that fixed-dose-rate (gemcitabine) infusion may be superior to bolus gemcitabine in the treatment of metastatic pancreas cancer. We wished to compare the radiosensitizing effects of fixed-dose-rate gemcitabine infusion to standard bolus injection. We measured weight loss and mouse intestinal crypt survival to determine equally toxic concentrations of gemcitabine administered through a 3-hour fixed-dose-rate infusion versus bolus injection in combination with fractionated radiation. To measure the effect of fixed-dose-rate gemcitabine infusion or bolus injection on radiosensitization, we treated mice bearing Panc-1 xenografts with equally toxic concentrations of gemcitabine (100 mg/kg fixed-dose-rate infusion or 500 mg/kg bolus injection) and fractionated radiation and monitored tumor growth. We found that 100 mg/kg gemcitabine through fixed-dose-rate infusion produced the same weight loss and intestinal crypt toxicity as the 500 mg/kg bolus injection. In nude mice bearing Panc-1 xenografts, fixed-dose-rate gemcitabine infusion produced greater radiosensitization than bolus injection with tumor doubling times of 44 +/- 5 versus 29 +/- 3 days, respectively (*P < .05). Fixed-dose-rate gemcitabine infusion produced enhanced radiosensitization without additional normal tissue toxicity compared to bolus gemcitabine injection. These data support an ongoing clinical trial using fixed-dose-rate gemcitabine infusion combined with conformal radiation in the treatment of locally advanced pancreatic cancer.     

In vivo effects of recombinant human interleukin 6, alone or in combination with local irradiation, on tumor growth in Lewis lung carcinoma-bearing mice

Lewis lung carcinoma (LLC)-bearing mice were used as a mouse model to evaluate effects of recombinant human (rh) interleukin (IL) 6 and local X-irradiation (LR) on the growth of primary tumors and lung metastases. Mice were inoculated s.c. with LLC tumor cells and then treated with rhIL-6 (100 ng/dose) s.c. twice a day (b.i.d.) for 5 days, beginning 6 days after tumor inoculation. LR (800 cGy) was administered to the site of the primary tumor 6 days after tumor inoculation and again 1 wk later. Mice were then observed for survival or sacrificed at day 21 after tumor inoculation to determine size of primary tumor, numbers and size of lung metastases, and other hematological parameters including numbers of granulocyte-macrophage progenitor cells (CFU-gm). The size of the primary tumor and numbers of lung metastases were reduced by rhIL-6. LR enhanced the antitumor effect of rhIL-6 significantly, while LR alone had only a slight antitumor effect. Tumor-associated increases in peripheral blood, femoral marrow, splenic-nucleated cellularity, and marrow and splenic CFU-gm were reduced in mice treated with rhIL-6 plus LR. Prolonged survival time was observed only in tumor-bearing mice treated with rhIL-6 in combination with LR. The antitumor effects in vivo of rhIL-6 appear to be mediated indirectly as rhIL-6 had no effect on proliferation of LLC cells in vitro as assessed by colony and 3H-thymidine incorporation assays. These studies suggest that rhIL-6 may have therapeutic value in the treatment of certain malignancies, especially if used in combination with LR.     

LPS-induced serum TNF production and lethality in mice: effect of L-carnitine and some acyl-derivatives

The effect of L-carnitine and some of its acyl derivatives on serum TNF production and lethality in a murine experimental endotoxin shock model was investigated. In some instances, serum IL-6 production was also evaluated. In this experimental model, C57BL/6 mice received 30 mg/kg LPS (E. cell 055:B5) injected intraperitoneally, while L-carnitine and its derivatives were administered according to different schedules. Serum levels of TNF and IL-6 were evaluated 1 h following LPS injection. The treated animals were also monitored daily for differences in body temperature, feeding, and survival for 10 days after LPS injection. Although some derivatives were able to significantly affect TNF production, the marked decrease in serum TNF levels of LPS-treated mice was not paralleled by a substantial increase in survival.     

Chemo-immunotherapy of murine tumors using interleukin-2 (IL-2) and cyclophosphamide

Summary The antitumor effect of interleukin-2 (IL-2), alone and in combination with cyclophosphamide was assessed in mice with established sarcoma (MCA 105, H-2^b), carcinoma (M109, H-2^d) and T lymphoma (PIR-2, H-2^b). Whereas administration of IL-2 alone (5×10⁴–10×10⁴ U, i.p. twice daily, for 4–8 consecutive days) prolonged the survival of mice with the solid neoplasms, it enhanced tumor growth and decreased survival of mice with the lymphoma. In the PIR-2 lymphoma, no IL-2 receptor (TAC) could be detected, nor could we demonstrate IL-2 tumor growth stimulation in vitro. A synergistic therapeutic effect was achieved in mice with the solid tumors, but not in mice with the lymphoma, only when IL-2 was given 1–4 days after cyclophosphamide (100–200 mg/kg). Conversely, administration of IL-2 1–4 days prior to cyclophosphamide resulted, in all three tumor systems, in enhanced tumor growth and in decreased survival as compared with mice receiving cyclophosphamide alone. Similarly, treatment with IL-2 both before and after cyclophosphamide was less efficacious than a single course of IL-2 given after-wards. It is concluded that for maximal therapeutic efficacy, IL-2 should be administered following chemotherapy, and that certain tumors may respond adversely to IL-2 treatment.     

Effect of intratumoral injection of carboplatin combined with pluronic P85 or L61 on experimental colorectal carcinoma in rats

Pluronic, a poly(ethylene oxide)-poly(propylene oxide)-poly (ethylene oxide) block copolymer, has been shown to enhance the cytotoxic activity of anticancer drugs in various cell lines. In the current study the effect of Pluronic P85 (P85) and Pluronic L61 (L61) on the intratumoral chemotherapy of an experimental adenocarcinoma in rats was examined. A total of 120 subcutaneous tumors (4 per rat) were inoculated in 30 BDIX rats and were treated weekly for 4 weeks with intratumoral injection of carboplatin (CPt) alone or with either P85 or L61. Tumors were monitored weekly and were excised at the endpoint for histologic evaluation. The effect of Pluronic on levels of intracellular ATP was explored as a possible mechanism of sensitization. Results showed that tumors treated with low-dose CPt (2.8 mg/kg) and P85 or L61 exhibited significant reductions in tumor volume after 28 days relative to Day 0 (112.7% +/- 34.4%, n = 15; 131.3% +/- 55.6%, n = 8) compared with tumors treated with free drug (339.4% +/- 75.0%, n = 16). Control tumors treated with either P85 or L61 alone or with saline showed volume increases of 1079.4% +/- 143.6% (n = 16), 729.4% +/- 202.2% (n = 7), and 1119.2% +/- 6.1% (n = 16), respectively. Treatment with high-dose CPt (20.7 mg/kg) led to a 79.3% +/- 4.2% reduction in tumor volume, and no differences were noted with addition of P85 or L61. In vitro ATP measurements showed that 28.0 mg/kg of P85 significantly reduced levels of intracellular ATP to 44.7% +/- 1.5% of controls, whereas L61 at this concentration depleted ATP levels completely. Results confirm that Pluronic P85 and L61 act as potent sensitizers to carboplatin chemotherapy of the experimental colorectal carcinoma, leading to a significant reduction of tumor growth compared to carboplatin alone. ATP depletion is a possible mechanism for these observed differences.     

Oxidations of 17beta-estradiol and estrone and their interconversions catalyzed by liver, mammary gland and mammary tumor after acute and chronic treatment of rats with indole-3-carbinol or beta-naphthoflavone.

Altered cytochrome P450-catalyzed metabolism of 17beta-estradiol (E2) and estrone (E1) in the liver and (or) extrahepatic tissues may affect estrogen-sensitive tumorigenesis. We examined the effects of oral treatments of (i) indole-3-carbinol (13C) at 250 or 500 mg/kg or beta-naphthoflavone (beta-NF) at 40 mg/kg of body weight (bw)/day from 51 to 54 days of age (acute regimen), and (ii) 13C at 250 mg/kg or beta-NF at 20 mg/kg bw given 3x/week from 10 to 22 weeks of age (chronic regimen) in female Sprague-Dawley rats. We determined the effects of these treatments on the P450 content and P450 (CYP)-specific activities in the liver, P450-dependent metabolism of E2 and E1 by the liver and mammary gland, and interconversion of E1 and E2 catalyzed by 17beta-hydroxysteroid dehydrogenase (17beta-HSD) in these tissues and malignant mammary tumors. 13C at the two levels of acute regimen elicited similar responses. Acute and chronic treatments with 13C, but not beta-NF, increased P450 content approximately 2-fold. 13C, and to a lesser extent beta-NF, increased CYP1A1 and CYP1A2 probe activities in liver up to 117- and 27- fold, respectively, and after acute regimens, that of CYP3A by approximately 1.8-fold. 13C also increased activity of CYP2B up to 100-fold. Overall hepatic metabolism of E2 and E1, which was approximately 2-fold greater at 55 than 155 days of age, was increased (approximately 2.8-fold) by 13C with 2-, 4-, 16alpha-, 6alpha-, 6beta-, and 15alpha-hydroxy (OH) comprising > or = 54, 3, 2, approximately 2, approximately 5, 7, and 2%, respectively, of E1 and E2 metabolites. Acute regimens of beta-NF increased 2- and 15alpha-OH-E2 (62 and 5% of total) from E2 and 2-, 4-, and 6alpha-OH-E1 + 6beta-OH-E1 (32, 13, and 4% of total) from E1. Mammary gland metabolized E2 to E1 and small amounts of 15alpha-, 4-, 16alpha-, 6beta-, and 6alpha-OH-E2. After the acute IC3 regimen, E2 was also converted to 2-OH-E2. 17Beta-HSD-catalyzed oxidation of E2 was favored in the liver and reduction of E1 was favored in mammary gland and tumor (= 1% of hepatic activity). An increased (approximately 2-fold) ratio of reductive to oxidative activities in malignant mammary tumors by chronic 13C regimen may stimulate tumor growth. This is the first report showing that after chronic oral regimens, the 13C-, but not beta-NF-, induced changes in CYP complement led to elevated E2 and E1 metabolism. The persistent effects of increased putative carcinogenic and estrogenic 4- and 16alpha-OH as well as 6alpha- and 6beta-OH-E2 and 6beta-OH-E1 might counteract those of the less estrogenic 2-OH metabolites, thus accounting for the lack of suppression of mammary tumorigenesis by 13C in our previous study.     

Effects of moderate exercise and oat beta-glucan on lung tumor metastases and macrophage antitumor cytotoxicity.

Both moderate exercise and the soluble fiber beta-glucan can have beneficial effects on the initiation and growth of tumors, but the data are limited, and there is no information on their combined effects. This study tested the independent and combined effects of short-term moderate-exercise training and the soluble oat fiber beta-glucan (ObetaG) on the metatastic spread of injected tumor cells and macrophage antitumor cytotoxicity. Male C57BL/6 mice were assigned to one of four groups: exercise (Ex)-H2O, Ex-ObetaG, control (Con)-H2O, or Con-ObetaG. ObetaG was fed in the drinking water for 10 days before tumor administration and death. Exercise consisted of treadmill running (1 h/day) for 6 days. After rest or exercise on the last day of training, syngeneic B16 melanoma cells (2 x 10(5)) were administered via intravenous injection (n = 8-11 per group). Lungs were removed 14 days later, and tumor foci were counted. Additional mice (n = 8 per group) were killed, and peritoneal macrophages were assayed for cytotoxicity against the same mouse tumor cell line at various effector-to-target ratios. Both moderate exercise and ObetaG decreased lung tumor foci and increased macrophage cytotoxicity. However, there were no differences in lung tumor foci and macrophage cytotoxicity between Ex-ObetaG and either Ex-H2O or Con-ObetaG. These data suggest that, although not additive in their effects, both short-term moderate-exercise training and consumption of the soluble ObetaG can decrease the metatastic spread of injected B16 melanoma cells, and these effects may be mediated in part by an increase in macrophage cytotoxicity to B16 melanoma.     

The effect of different doses of cisplatin on the pharmacokinetic parameters of cefepime in mice

The simulation of human serum levels is essential in animal models to extrapolate the experimental results to clinical practice. Administration of a nephrotoxic drug such as cisplatin can be used to cause renal dysfunction as an approach to mimic human serum levels of renally excreted drugs. We aimed to determine the dose of cisplatin that did not affect the survival rate of mice and to achieve human-like serum concentrations of cefepime. Different doses of cisplatin (0, 10, 14, 18, 22 and 26 mg/kg) were given by intraperitoneal (i.p.) injection to mice three days prior to the i.p. administration of 80 mg/kg cefepime. With cisplatin doses of 18 and 22 mg/kg, the half-life of cefepime was significantly prolonged (P < 0.001) and all mice survived. The pretreatment with 26 mg/kg cisplatin significantly decreased survival (P = 0.001), but the half-life of cefepime was not significantly longer than of 18 mg/kg cisplatin. Serum levels of cefepime after the pretreatment with 18 mg/kg cisplatin were comparable to published human data. The administration of cisplatin appears to be a suitable method in mice for simulating human serum concentrations of renally excreted drugs.     

Protective effect of various antioxidants on the toxicity of sulphur mustard administered to mice by inhalation or percutaneous routes

Protective effect of various antioxidants, trolox (water soluble analogue of vitamin E), quercetin (bioflavonoid) and glutathione reduced (GSH), was studied following sulphur mustard (SM) intoxication. SM, a blistering agent was administered to Swiss albino female mice through inhalation (1 LC50=42.3 mg/m3 for 1 h duration; 14 days observation for mortality) and percutaneous (1 LD50=154.7 mg/kg; 7 days observation for mortality) routes. The antioxidants were administered three times at the dose of trolox, 500 microg/kg; quercetin, 5 mg/kg and GSH, 400 mg/kg body weight by intraperitoneal injection, one immediately following SM exposure, then once each day for 2 days after SM treatment. The effect of antioxidants on survival, markers of oxidative damage and purine metabolites was investigated. Survival study animals were observed for 14 days. Oxidative markers (in blood, liver and lung) and purine metabolites (in blood and urine) were investigated 72 h after SM treatment. Survival time increased significantly following trolox and quercetin treatments through the inhalation route. Significant decrease in GSH and increase in the level of malondialdehyde (MDA) indicated oxidative damage to liver and lung tissues following SM inhalation and percutaneous exposure. Blood and urinary uric acid, end product of purine metabolism showed an increased following both routes of exposures. The antioxidants, trolox and quercetin protected the liver and lung tissues from oxidative damage caused by SM exposure through inhalation and percutaneous routes. This study showed that antioxidants could enhance survival time, protect liver and lung from oxidative damage and reduce accumulation of purine metabolites in blood following SM intoxication.     

跑台干预对多柔比星抗肿瘤效果和心毒性的影响

本研究旨在探讨利用多柔比星进行抗肿瘤治疗前先行跑台干预,对多柔比星抗肿瘤效果及其诱发的心毒性可能造成的影响。本研究采用50只12周龄的C57BL/6小鼠为实验对象,随机分为C组(对照组,n=10)、SNTD组(不运动+无肿瘤+多柔比星组, n=10)、STS组(不运动+肿瘤+安慰剂, n=10)、STD组(不运动+肿瘤+多柔比星组, n=10)、ETD组(运动+肿瘤+多柔比星组, n=10),进行2周的不同方案干预后,在STS组、STD组、ETD组大鼠注射黑色素肿瘤细胞,C组、ETD组注射等量的生理盐水。注射后3周,在SNTD组、STD组、ETD组小鼠的腹腔注射12 mg/kg的多柔比星,C组和STS组注射等量生理盐水。注射结束10 d后,进行心脏形态功能和肿瘤体积检查,利用SPSS进行统计分析。本研究认为多柔比星能够抑制肿瘤流体生长速度,但跑台运动不会对多柔比星抗肿瘤的效果产生影响。注射多柔比星会导致心壁变薄、心输出量、射血量等心脏功能衰退,但跑台运动能够缓解多柔比星的心毒性。     

Effects of steroid administration on pituitary luteinizing hormone and follicle-stimulating hormone in ovariectomized pony mares in the early spring: pituitary responsiveness to gonadotropin-releasing hormone and pituitary gonadotropin content

These experiments tested the hypothesis that administration of steroid hormones to ovariectomized (OVX) mares during the vernal transition to the breeding season would influence LH and FSH secretion. Circulating gonadotropin concentrations, response to exogenous GnRH, and pituitary gonadotropin content were monitored. Experiments 1 and 2 were conducted, beginning 10 March, and 3 February, respectively, utilizing a total of 30 long-term OVX pony mares. In experiment 1, mares were administered vehicle (n = 5) or estradiol-17 beta (E2, n = 5, 5 mg/3 ml sesame oil), twice daily for 16 days. Blood samples were collected daily for assessment of circulating LH and FSH concentrations. On Day 10 of treatment, 400 micrograms GnRH were administered to all mares. LH increased significantly over days of treatment in the estradiol-treated group, but pituitary response to GnRH tended to be less than in control mares. Circulating FSH tended to decline over days of treatment in estradiol-treated mares, and the pituitary response to GnRH was significantly reduced. Pituitary LH, but not FSH, was increased on Day 16 of treatment with estradiol. In experiment 2, 20 OVX mares received, twice daily, vehicle (n = 5), E2, n = 5; 5 mg), progesterone (P4, n = 5; 100 mg), or progesterone plus estradiol (P4/E2, n = 5; 100 + 5 mg). Treatment continued for 14 days. GnRH (100 micrograms) challenges were administered on Days 6 and 13 of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Modulation of murine macrophage function by N-acetylcysteine in a model of endotoxic shock

In previous studies we have observed changes in several functions of peritoneal macrophages from BALB/c mice with irreversible endotoxic shock caused by intraperitoneal injection of E. coli lipopolysaccharide (LPS) (100 mg/kg), which were associated with a high production of superoxide anion. Since antioxidants, such as N-acetylcysteine (NAC), are free radical scavengers that improve the immune response, in the present work we have studied different functions of peritoneal macrophages from BALB/c mice suffering the endotoxic shock above indicated and administered N-acetylcysteine (150 mg/kg i.p.) at 30 minutes after LPS injection. In the peritoneal macrophages obtained at 2, 4, 12 and 24 h after LPS injection, the following functions were studied: adherence to substrate, mobility, ingestion of particles, and production of superoxide anion and tumour necrosis factor (TNF alpha). The increase in adherence, ingestion and superoxide anion and TNF alpha production shown by macrophages from animals with endotoxic shock was counteracted by NAC injection. Moreover, the survival time of mice with endotoxic shock was increased in the presence of NAC. These data suggest that NAC, administered intraperitoneally, may be useful for the treatment of irreversible endotoxic shock by modulation of the function of macrophages with decreased superoxide anion and TNF alpha production and concomitant increase of survival time.