PLGA-5-氟尿嘧啶缓释微球治疗结直肠癌裸鼠的探讨

目的研究PLGA-5-氟尿嘧啶缓释微球瘤周给药对结直肠癌移植瘤的治疗效果。方法将60只结直肠癌荷瘤鼠随机分为6组,每组10只。A、B组瘤周注射PLGA-5-氟尿嘧啶缓释微球,5-氟尿嘧啶剂量分别为200mg/kg和100 mg/kg;C、D组瘤周注射5-氟尿嘧啶注射液,5-氟尿嘧啶剂量分别为200 mg/kg和100 mg/kg;E组瘤周注射PLGA微球,800 mg/kg;F组不给予任何治疗。于0、3、6、9、12、15d观察裸鼠生存状况、称体重、测量肿瘤大小。15d时处死动物,称瘤重,计算抑瘤率,绘制肿瘤生长曲线;取血行白细胞计数、肝肾功能检查。结果A、B组肿瘤生长曲线平缓,15 d时A、B组肿瘤体积与C、D、E、F组比较,结果差异有显著性,C、D组肿瘤体积与E、F组比较差异无显著性;A、B组抑瘤率分别为75%和62%,与C、D组比较,结果差异有显著性;A、B、C、D、E组体重在0 d及15 d与F组比较,差异无显著性,15 d时各组白细胞计数及肝肾功能检查值均在正常范围。结论PLGA-5-氟尿嘧啶缓释微球瘤周给药能有效抑制结直肠癌移植瘤的生长,且无明显的毒副作用。     

Enhancement of biliary excretion of aflatoxin B(1) and suppression of hepatic ornithine decarboxylase activity by 2-(allylthio)pyrazine in rats.

2-(Allylthio)pyrazine (2-AP), a synthetic pyrazine derivative with an allylsulfur moiety, has protective effects against chemically-induced hepatic toxicity. Previous studies have shown that 2-AP significantly reduces the formation of preneoplastic foci in rats exposed to aflatoxin B(1) (AFB(1)). The present study was designed to determine whether 2-AP could increase the biliary excretion of metabolites of AFB(1) in rats treated with this carcinogen and whether the agent could alter the activity of ornithine decarboxylase (ODC), which is considered to be associated with tumor promotion. Rats were pretreated with 2-AP (p.o.) at a daily dose of 50 mg/kg for 5 consecutive days. AFB(1) (5 mg/kg) was administered intraperitoneally 2 h after the last dose of 2-AP. Amounts of principal AFB(1) metabolites, AFB(1)-glutathione and a glucuronide conjugate secreted in bile juice was increased by 56 and 50%, respectively, after the 2-AP treatment. Levels of radiolabelled AFB(1) covalently bound to calf thymus DNA catalyzed by microsomes obtained from 2-AP-treated rats (10 and 50 mg/kg, for 5 days) were reduced by 47 to 66%. ODC activity in AFB(1)-treated rats was determined by the three-step medium-term hepatocarcinogenesis assay. Rats were treated with 2-AP at the daily doses of 10, 25 and 50 mg/kg for 16 consecutive days. During this period, four repeated doses of AFB(1) (1.0 mg/kg) were given to the animals. Rats were then subjected to two-third partial hepatectomy, followed by administration of phenobarbital. 2-AP inhibited AFB(1)-induced ODC activity by 40 to 66%, as determined at the 44th day. Inhibition of AFB(1)-induced ODC activity by 2-AP in conjunction with acceleration of AFB(1) elimination through metabolic conjugation may contribute to its chemopreventive effects against this carcinogen.     

In vivo growth inhibitory effect of Withania somnifera (Ashwagandha) on a transplantable mouse tumor, Sarcoma 180.

Withania somnifera is a medicinal plant used in the treatment of a variety of ailments in the Ayurvedic system. Alcoholic extract of the root of the plant was injected(ip) at daily doses of 200 to 1000 mg/kg body wt for 15 days starting from 24 hr after intradermal inoculation of 5 x 10(5) cells of S-180 in BALB/c mice. Solid tumor growth was monitored for 100 days. Doses of 400 mg/kg and above produced complete regression of tumor after an initial growth, the percentage of complete response (CR) increasing with increasing drug dose. A 55% CR was obtained at 1000 mg/kg drug administration, but this dose also produced some mortality among the animals. A significant increase in the volume doubling time and growth delay was seen when the drug dose was increased from 500 to 750 mg/kg body wt, but further increase in drug dose to 1000 mg/kg did not produce any significant increase in these responses. Cumulative doses of 7.5 to 10 g at daily doses of 500 or 750 mg/kg seems to produce a good response in this tumor.     

Piracetam modifies morphine and related drug-induced elevation of serum corticosterone concentration in rats

Piracetam (2-oxo-l-pyrrolidine acetamide, UCB 6215) or physiological saline solution was injected intravenously to female rats; after 60 min the animals were decapitated and blood was collected. Piracetam in doses of 100, 300 and 600 mg/kg resulted in a progressive suppression of serum corticosterone concentration (Cpd B) as compared to the controls. Morphine (5 and 10 mg/kg), nalorphine (5 and 10 mg/kg) and naloxone (0.5 mg/kg) induced a significant rise of Cpd B 30 min after subcutaneous injection, however, this could be prevented by 300 mg/kg piracetam given intraperitoneally 60 min prior to decapitation. Piracetam was ineffective in reducing the effects of high doses of morphine (20 mg/kg) and nalorphine (20 mg/kg). The drug had no effect on either ether stress or electric footshocks induced activation of the pituitary-adrenocortical system. In vitro the drug had no effect on pituitary ACTH release following exposure to crude hypothalamic extract. It is concluded that the effect of piracetam on the pituitary-adrenocortical axis is mediated through hypothalamic or extrahypothalamic brain structures and influences one of the effects of morphine and related drugs.     

Induction of rat hepatic drug metabolizing enzymes by dimethylcyclosiloxanes

Low molecular weight dimethylcyclosiloxanes (DMCS) are important precursors in the synthesis of polydimethysiloxane polymers widely used in industry, and in medical and personal care products. The objective of this study was to characterize the ability of two DMCS, octamethylcyclosiloxane (D4) and decamethylcyclopentasiloxane (D5) to induce drug metabolizing enzymes in rats. Male and female Sprague-Dawley rats were administered 1, 5, 20, or 100 mg/kg D4 or D5 in corn oil daily by gavage for 4 days. Changes in the levels of activity and/or immunoreactivity of CYP1A1/2, CYP2B1/2, CYP3A1/2 and NADPH cytochrome P450 reductase in liver microsomes were examined. Significant increases were observed in the liver to body weight ratio in female rats administered either D4 or D5 at doses > or = 20 mg/kg. Increases in the liver to body weight ratio were observed in male rats treated with > or = 100 mg/kg D5 but not with D4. Relatively large increases in CYP2B1/2 enzymatic activity and immunoreactive protein were observed with increasing concentrations of both D4 and D5. Significant increases in 7-pentoxyresorufin O-depentylase (PROD) activity were also detected in male and female rats given D4 at doses > or = 5 mg/kg. D5 increased PROD activity in male rats at doses > or = 20 mg/kg and in female rats at doses > or = 5 mg/kg. 7-Ethoxyresorufin O-deethylase (EROD) activity was increased in both male and female rats receiving > or = 20 mg/kg D4 or > or = 5 mg/kg D5; however, no changes were detected in CYP1A1/2 immunoreactive protein in rats of either sex. D4 and D5 caused significant increases in CYP3A1/2 immunoreactive protein in only male rats treated with 100 mg/kg of either compound. However, significant increases were detected in CYP3A1/2 immunoreactive protein in female rats at D4 doses > or = 20 mg/kg and D5 doses > or = 5 mg/kg. Induction of NADPH cytochrome P-450 reductase immunoreactive protein was observed with D4 in female rats and in both male and female rats with D5. Induction of CYP2B/1/2, CYP3A1/2 and NADPH cytochrome P450 reductase was observed in rats treated with 50 mg/kg phenobarbital by intraperitoneal injection. Maximal CYP2B induction detected with D4 was approximately 50% of the increase observed with phenobarbital. In summary, D4 and D5 induced CYP2B1/2 in adult rat liver in a manner similar to that observed with phenobarbital; however, differences were observed between D4 and D5 in their ability to induce CYP3A1/2 and NADPH cytochrome P450 reductase. Female rats were more sensitive to the inductive properties of low doses of both DMCS than male rats whereas male rats were more responsive to phenobarbital induction.     

Modulation of hematologic and immunologic effects of high dose chemotherapy by interleukin-2 in a murine tumor model.

To determine if intensive chemotherapy consisting of cyclophosphamide (C), etoposide (E), and cisplatin (P) (CEP) may be usefully combined with recombinant human interleukin-2 (rhIL-2), we examined a murine tumor model designed to approximate a common clinical situation: macroscopic, drug-resistant cancer. Using C57BL/6 mice with extensive tumor burden 10 days after intravenous B16 melanoma cell injection, we observed (1) C, E, and P synergize to enhance survival but do not cure mice at the highest tolerable dose (C = 200 mg/kg, E = 60 mg/kg, and P = 3 mg/kg); (2) rhIL-2 at 3 x 10(5) U (subcutaneously) daily for 4 days administered 10-18 days after B16 injection significantly improves survival; (3) CEP plus rhIL-2 is more effective than CEP alone only when rhIL-2 is administered before CEP; (4) CEP suppresses IL-2-induced lymphokine-activated killer cell activity in the spleen; and (5) rhIL-2 protects mice incompletely from the immunologic and hematologic suppression of CEP. Our results suggest that intensive chemotherapy combined with rhIL-2 may be beneficial. The success of any such combination may be schedule dependent.     

Thermoregulatory, motor, behavioural, and nociceptive responses of rats to 3 long-acting neuroleptics

We investigated physiological effects of intramuscular injections of the following 3 long-acting neuroleptics commonly used in wildlife management: haloperidol (0.05, 0.1, and 0.5 mg/kg body mass), zuclopenthixol acetate (0.5, 1, and 5 mg/kg), and perphenazine enanthate (1, 3, and 10 mg/kg), in a rat model. Body temperature and cage activity were measured by intra-abdominal telemeters. Nociceptive responses were assessed by challenges to noxious heat and pressure. Haloperidol (0.5 mg/kg) produced a significant nocturnal hypothermia (p < 0.05) and decreased nighttime cage activity and food intake. Zuclopenthixol (5 mg/kg) significantly decreased nighttime body temperature and cage activity and, at 1 mg/kg and 5 mg/kg, significantly decreased food intake 5-17 h after injection (p < 0.05). Perphenazine (10 mg/kg) significantly decreased nighttime body temperature and cage activity and, at all doses, significantly decreased food intake 5-17 h after injection (p < 0.05). Significant analgesic activity was evident in rats given 5 mg/kg zuclopenthixol up to 40 h after injection, and 10 mg/kg perphenazine from 48 to 96 h after injection (p < 0.0001). Zuclopenthixol (5 mg/kg) and perphenazine (10 mg/kg) had significant antihyperalgesic activities at 16 h postinjection and 24-48 h postinjection, respectively (p < 0.0001). Haloperidol had no significant antinociceptive activity at doses tested. Motor function was impaired in rats given 0.5 mg/kg haloperidol, 5 mg/kg zuclopenthixol and 10 mg/kg perphenazine. Effects of long-acting neuroleptics on body temperature, feeding, and activity were short-lasted and should not preclude their use in wildlife. Antinociceptive actions were longer-lasting, but were nonspecific, and we recommend additional analgesics for painful procedures during wildlife management.     

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.     

Glycine modulates N-methyl-D-aspartic acid induced learning facilitation in rats

Summary Pretraining i.p. administration of N-methyl-D-aspartic acid (NMDA) at doses of 10 and 20mg/kg dose-dependently facilitated performance in a water T-maze learning task in rats. The effect of NMDA was inhibited by the competitive NMDA receptor antagonist CGP37849 [(DL)-E(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid] (CGP) at a dose of 6mg/kg, and by the NMDA receptor complex glycine site antagonist 1-hydroxy-3-amino-2-pyrrolidone (HA-966) at a dose of 10mg/kg. The NMDA site antagonist, when given alone, did not impair learning. The glycine precursor milacemide (2-N-pentylaminoacetamide HCl), at doses of 5 and 10mg/kg accelearted learning acquisition and its effect was antagonized by HA-966. The learning rate was impaired following the administration of NMDA 10mg/kg together with milacemide 5mg/kg when compared with the effect of 10mg/kg NMDA alone.The administration of 5mg/kg NMDA was associated with an elevated tissue concentration of aspartate in the hippocampus, an effect which was antagonized by 6mg/kg of CGP. NMDA at doses of 10 and 20mg/kg elevated the concentration of glycine but decreased the concentration of aspartate, glutamate and glutamine in the cortex and aspartate in the hippocampus. The cortical effects of NMDA 10mg/kg were antagonized by 6mg/kg of CGP. Milacemide at the dose of 10mg/kg elevated glycine, aspartate, glutamate and taurine concentrations. The coadministration of 5 mg/kg NMDA with 5mg/kg milacemide elevated the concentrations of glycine, glutamate and glutamine in the cortex and taurine in the hippocampus. These amino acid levels were higher than after administration of 5mg/kg either agent alone. The results demonstrate a dose-dependent facilitation effect on learning performance by NMDA and glycine receptor agonists. Antagonists at the NMDA and glycine sites counteracted the learning improvement of NMDA, and the glycine site antagonist the effect of milacemide.     

Melatonin reverses neurochemical alterations induced by 6-OHDA in rat striatum

The present work showed that the intrastriatal injection of 6-OHDA significantly decreases DA, DOPAC and HVA levels in that rat brain structure. Although there is also a decrease in 5-HT levels no changes were observed in 5-HIAA levels as compared to controls. On the other hand, melatonin (2, 5, 10 and 25 mg/kg. i.p., daily for 7 days) treatment starting 1 h after 6-OHDA lesions, partially reverses the decreases caused by 6-OHDA lesions on these neurotransmitter levels, and contents were brought to approximately 50% of that observed in the contralateral sides of controls or of melatonin treated group. Melatonin was more efficient at the doses of 5 and 10 mg/kg, i.p., and effects were similar between the lowest and highest doses characteristic of a bell-shaped type of response. The apomorphine-induced rotational behavior (3 mg/kg, i.p.) was blocked by 60, 89, 78 and 47% after the doses of 2, 5, 10 and 25 mg/kg, i.p., respectively. Similarly, in this case the doses of 5 and 10 mg/kg were also more efficient. Melatonin (5 mg/kg) produced an upregulation of D1 receptors associated with a decrease in Kd value. While no change was observed in maximum density of D2 receptors, the Kd value was also decreased.     

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.     

Acrylonitrile: in vivo cytogenetic studies in mice and rats

Acrylonitrile (VCN), a suspect human carcinogen, does not produce significant increases in cytogenetic aberrations in the mouse-bone marrow when given orally for 4, 15 or 30 days at doses equal to 7, 14 and 21 mg/kg/day resp. or by i.p. for the same time periods at doses of 10, 15 and 20 mg/kg/day. Rats treated orally with 16 daily doses of VCN (40 mg/kg/day) or potassium cyanide (KCN) (5 mg/kg/day) showed no increase of aberrant metaphases in the bone marrow over controls.     

Effect of <Emphasis Type="Italic">Streptomyces</Emphasis> 23-2B metabolites on hepatic lipid peroxidation and some antioxidant parameters in Wister rats

Streptomyces 23-2B is one of actinomycetes associated with marine clam Donax trunculus and has potential source of bioactive metabolites, which possesses a broad spectrum antibiotic and anticancer activities. This study aims to evaluate the effect of Streptomyces 23-2B metabolites on hepatic lipid peroxidation (LPO), reduced glutathione (GSH) levels, as well as serum uric acid, total cholesterol (TC), triglyceride (TG), nitric oxide (NO) and tumor necrosis factor-alpha (TNF-α) levels of rat. Animals were divided into four groups: the control group, which received 0.1 ml of 10% Tween-80 by intraperitoneally injection, and the other three experimental groups, which received 10% Tween 80 solution of Streptomyces 23-2B metabolites in doses of 0.5, 5 and 50 mg/kg body weight at an interval 2 days for 2 weeks. LPO levels showed significant decrease with the lowest doses. The effect at a dose of 50 mg/kg of Streptomyces 23-2B metabolites on TG was more pronounced than the other two doses (0.5 and 5 mg/kg body weight). Hypocholesterolemia was recorded in the treated rats with 0.5 and 5 mg/kg of Streptomyces 23-2B. However, the highest dose enhanced the elevation of serum TNF-α and NO levels. Thus, the present study reveals that Streptomyces 23-2B metabolite is a newly discovered biomaterial from microorganisms. The novel substance showed inhibitory activity against LPO in rat liver homogenate and improving the immune response by releasing TNF-α and NO in serum.     

Antitumor effects of the molecule-downsized immunoconjugate composed of lidamycin and Fab′fragment of monoclonal antibody directed against type IV collagenase

Type IV collagenase plays an important role in tumor invasion and metastasis through cleaving type IV collagen in the basement membrane and extracellular matrix. In this study a molecule-downsized immunoconjugate (Fab'-LDM) was constructed by linking lidamycin (LDM), a highly potent antitumor antibiotic, to the Fab' fragment of a monoclonal antibody directed against type IV collagenase and its antitumor effect was investigated. As assayed in 10% SDS-PAGE gel, the molecular weight of Fab'-LDM conjugate was 65 kD with a 1 : 1 molecular ratio of Fab' and LDM. The Fab'-LDM conjugate maintained most part of the immunoreactivity of Fab' fragment to both type IV collagense and mouse hepatoma 22 cells by ELISA. By MTT assay, Fab'-LDM conjugate showed more potent cytotoxicity to hepatoma 22 cells than that of LDM. Administered intravenously, Fab'-LDM conjugate proved to be more effective against the growth of subcutaneously transplanted hepatoma 22 in mice than free LDM in two experiment settings. In Experiment     

The role of putative 5-HT1A and 5-HT1B receptors in the control of feeding in rats

8-hydroxy-2(di-n-propylamino)tetraline (8-OH-DPAT) and 5-methoxy-3(1,2,3,6-tetrahydro-4-pyridinyl)1H indole succinate (RU 24969), two agonists on the putative serotonin 1A and serotonin 1B receptors, were used for exploring the role of these sites in the inhibitory effect of serotonin (5-HT) on feeding. In free-feeding rats, 2.5-5 mg/kg RU 24969 significantly reduced food intake while doses of 8-OH-DPAT ranging from 0.125 to 0.5 mg/kg increased eating. The effects of the highest doses were associated with hyperlocomotion and hyperreactivity for RU 24969 and a typical motor syndrome (flat body posture and forepaw treading) for 8-OH-DPAT. The motor syndrome caused by 0.5 mg/kg 8-OH-DPAT was much more obvious in food-deprived rats in which food intake was also markedly reduced. RU 24969 1.25 and 5 mg/kg reduced food intake by food-deprived rats and caused hyperlocomotion not different from that in free-feeding animals. Pretreatment with metergoline (2 mg/kg i.p.) prevented the effect of 5 mg/kg RU 24969 on food intake by food-deprived rats but had no effect on the reduction of eating caused by 0.5 mg/kg 8-OH-DPAT. The motor syndrome caused by 8-OH-DPAT was not changed by metergoline but the hyperlocomotion caused by RU 24969 was potentiated. Haloperidol (0.1 mg/kg i.p.) completely blocked the hyperlocomotion but did not change the reduction of food intake caused by RU 24969 in food-deprived rats. It is suggested that the putative serotonin 1B receptors specifically mediate the inhibitory effect of 5-HT on feeding whereas serotonin 1A sites act by enhancing eating only in free-feeding animals.     

Inhibition of cancer growth by resveratrol is related to its low bioavailability

The relationship between resveratrol (RES) bioavalability and its effect on tumor growth was investigated. Tissue levels of RES were studied after i.v. and oral administration of trans-resveratrol (t-RES) to rabbits, rats, and mice. Half-life of RES in plasma, after i.v. administration of 20 mg t-RES/kg b.wt., was very short (e.g., 14.4 min in rabbits). The highest concentration of RES in plasma, either after i.v. or oral administration (e.g., 2.6 +/- 1.0 microM in mice 2.5 min after receiving 20 mg t-RES/kg orally), was reached within the first 5 min in all animals studied. Extravascular levels (brain, lung, liver, and kidney) of RES, which paralleled those in plasma, were always < 1 nmol/g fresh tissue. RES measured in plasma or tissues was in the trans form (at least 99%). Hepatocytes metabolized t-RES in a dose-dependent fashion (e.g., 43 nmol of t-RES/g x min in the presence of 20 microM tRES), which means that the liver can remove circulating RES very rapidly. In vitro B16 melanoma (B16M) cell proliferation and generation of reactive oxygen species (ROS) was inhibited by t-RES in a concentration-dependent fashion (100% inhibition of tumor growth was found in the presence of 5 microM t-RES). Addition of 10 microM H(2)O(2) to B16M cells, cultured in the presence of 5 microM t-RES, reactivated cell growth. Oral administration of t-RES (20 mg/kg twice per day; or included in the drinking water at 23 mg/l) did not inhibit growth of B16M inoculated into the footpad of mice (solid growth). However, oral administration of t-RES (as above) decreased hepatic metastatic invasion of B16M cells inoculated intrasplenically. The antimetastatic mechanism involves a t-RES (1 microM)-induced inhibition of vascular adhesion molecule 1 (VCAM-1) expression in the hepatic sinusoidal endothelium (HSE), which consequently decreased in vitro B16M cell adhesion to the endothelium via very late activation antigen 4 (VLA-4).     

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.     

Mutagenicity studies with nitrofurans. I. Mutagenicity of nitrofurylacrylic acid for mammals

Cytogenetic analysis of mouse bone-marrow cells, the dominant lethal test in mice and the cytogenetic analysis of human peripheral lymphocytes in vitro were used to study the mutagenicity of 3-(5-nitro-2-furyl)acrylic acid (5-NFA) for mammals. The bone-marrow cytogenetic analysis was performed in female mice exposed to 5-NFA administered intraperitoneally in single doses of 15--120 mg/kg and in 5 repeated doses of 15 and 30 mg/kg, intragastrically in single doses of 30--240 mg/kg and 5 repeated doses of 30 and 60 mg/kg, and perorally for 12 weeks to 5-NFA concentration of 10, 100 and 1000 mg 5-FNA/1 in drinking water. The bone-marrow analysis was performed in this case after 12 days, 3, 4, 6, 8, 10 and 12 weeks exposure. No increase in chromosome damage attributable to dosing with 5-NFA occurred in any of these experiments. Experiments in which mice were exposed to 5-NFA in drinking water for 12 weeks and then treated with a single i.p. dose of 2 mg of the mutagen TEPA [trix-(1-aziridinyl)phosphine oxide] per kg revealed that, at a concentration of 1000 mg 5-NFA/1, the clastogenic activity of TEPA was reduced to that in untreated animals. The dominant lethal test was performed in male mice exposed to 5-NFA applied intraperitoneally in single doses of 40--120 mg/kg and in 5 repeated doses of 10--30 mg/kg, intragastrically in 5 repeated doses of 20--60 mg/kg, and perorally for 4 weeks in drinking water containing 5-NFA at concentrations of 10, 100, 316 and 1000 mg/l. No significant differences were detected between the exposed and control groups of animals. Experiments in which male mice were exposed to 5-NFA in drinking water and treated after the 4-week exposure to 5-NFA with 1 mg TEPA/kg revealed that a concentration of 1000 mg 5-NFA/1 reduced TEPA-induced dominant lethality to within control values. A reduction in male fertility was observed after the single or repeated 5-NFA doses, but no changes when 5-NFA was applied in drinking water. The cytogenetic analysis of human peripheral lymphocytes exposed in vitro for the last 24 h of culture to concentrations of 1--100 micrograms 5-NFA/Ml did not show any compound-related chromosomal changes. The results of dominant-lethal and bone-marrow cytogenetic studies in mice after consumption of drinking water containing 1000 mg of 5-NFA/1 for 12 weeks and dosed subsequently with TEPA suggests that 5-NFA has some antimutagenic activity. Because none of the studies reported revealed any compound-related genetic activity, the results suggest that 5-NFA is not a chromosome-breaking agent in mammals.     

M&B 28,767: a potent anti-secretory and anti-ulcer PG analogue. A comparative study with 16, 16' dimethyl PGE2 methylester

M&B 28,767 [(+/-)11-deoxy-16-phenoxy-omega-tetranor PGE1] and 16, 16'-dimethyl PGE2 methylester (DMPG) were compared for their effects on gastric acid secretion (GAS) and gastric ulceration (GU), employing various laboratory models. In anaesthetised rats, GAS was stimulated by a continuous i.v. infusion of pentagastrin (30 micrograms/kg/h), and PG analogues were perfused through the stomach for 1 h. M&B 28,767 (3-15 micrograms/kg/h) and DMPG (3-60 micrograms/kg/h) reduced GAS in a dose-related manner, the ED50 values being 4 and 15 micrograms/kg/h respectively. In conscious rats possessing indwelling gastric cannulae, oral doses of M&B 28,767 (0.025-0.1 microgram/kg) and DMPG (0.50-1.0 microgram/kg) caused a prolonged inhibition of pentagastrin-stimulated GAS. M&B 28,767 was 17 times more potent than DMPG; the respective ED50 values were 0.036 and 0.6 microgram/kg. Indomethacin-induced ulceration in rats, was reduced by both M&B 28,767 and DMPG; the respective ED50 values being 3.0 and 0.8 micrograms/kg. Both compounds given orally increased gastrointestinal motility in mice; M&B 28,767 (1-3 mg/kg) and DMPG (0.1-0.3 mg/kg) caused diarrhoea, the former being about 0.1 times as potent as the latter. In another test, M&B 28,767 (0.5-5.0 mg/kg) and DMPG (10-40 micrograms/kg) overcame morphine-induced constipation in a dose-related manner, the respective ED50s being 0.9-1.4 mg/kg and 20-40 micrograms/kg. Thus, M&B 28,767 had a better profile of activity than DMPG as an antisecretory and antiulcer agent.     

Acute Toxicity of Ochratoxins A and B in Chicks

Ochratoxins A and B were given to 1-day-old Babcock B-300 cockerels to evaluate acute toxic effects. Two trials with ochratoxin A gave 7-day oral median lethal dose estimates of 116 mug (3.3 mg/kg) and 135 mug (3.9 mg/kg) per chick. Chicks given daily oral doses of 100 mug of ochratoxin A died on the second day. Single subcutaneous doses of 400 mug of ochratoxin A were also lethal. The 7-day oral median lethal dose of B was estimated at 1,890 mug (54 mg/kg) per chick. Chicks given oral doses of 100 mug of ochratoxin B daily for 10 days survived. Sublethal doses of both ochratoxins A and B resulted in growth suppression which was proportional to the amount of ochratoxin given. Visceral gout was the principal gross finding. Microscopic examinations revealed acute nephrosis, hepatic degeneration or focal necrosis, and enteritis. Suppression of hematopoiesis in the bone marrow and depletion of lymphoid elements from the spleen and bursa of Fabricius were frequently seen. Both ochratoxins appeared to have similar pathological effects. This is the first report on the toxicity of ochratoxin B.