Intrarectal administration of 5-aminosalicylic acid to rabbits and dogs

Intrarectal administration of 5-aminosalicylic acid (5-ASA) to rabbits and dogs was performed to obtain safety data. Groups of rabbits and dogs received twice daily intrarectal doses of 250, 500 or 1000 mg 5-ASA for 14 consecutive days. Treatment had no adverse effect on the behaviour or performance of the animals and microscopic examination revealed no evidence of systemic or local toxicity.

Anti-Gal antibodies in humans and 1, 3alpha-galactosyltransferase knock-out mice

BACKGROUND

Due to the absence of alphaGAL epitopes, humans and galactosyltransferase knock-out (GALT/ KO) mice express high levels of anti-Gal antibodies. We describe the properties of mouse anti-GAL antibodies.

METHODS

Anti-GAL IgG antibodies were quantified by affinity purification. Antibody affinities and avidities were determined in direct binding and competition assays. Antibody-mediated rejection was investigated using hyperimmunized GALT/KO mice as recipients of GAL+ heart allografts.

RESULTS

In young GALT/KO mice the levels of anti-GAL antibodies were low. Immunization of GALT/KO mice resulted in increased anti-GAL antibody expression. In mouse serum 0.6% of IgG was specific for alphaGAL compared to 0.5% in human serum. The avidity of purified mouse and human anti-GAL IgG was 30 and 6 nM, the affinity 15 and 50 microM, respectively. The isotype distribution in mouse and human anti-GAL IgG appeared to be similar to the isotype distribution in normal sera. The affinity of mouse and human anti-GAL IgM was 150 and 750 microM, respectively. Immunized GALT/KO recipients of GAL+ heart transplants rejected their grafts within 2 hr although nonimmunized GALT/KO mice retained their grafts for up to 6 days. Immunohistological examination of the rejected GAL+ hearts revealed massive deposition of IgM and IgG on endothelial cells of the graft with a concomitant deposition of complement.

CONCLUSIONS

Our studies demonstrate that anti-GAL antibodies from immunized GALT/KO mice bind alphaGAL with an avidity/affinity similar to human anti-GAL antibodies and are able to induce hyperacute rejection of GAL+ heart allografts.

Protection against lethal Escherichia coli bacteremia in baboons (Papio anubis) by pretreatment with a 55-kDa TNF receptor (CD120a)-Ig fusion protein, Ro 45-2081

Fusion proteins of the human 55-kDa TNF receptor extracellular domain with hinge and C2/C3 constant domains of human IgG1 or IgG3 heavy chains were tested in a primate sepsis model. Twenty-four baboons received 4.6, or 0.2 mg/kg of TNFR5-G1,3, or placebo, before the administration of a lethal dose of live Escherichia coli. Treatment with TNFR5-G1,3 decreased 5-day mortality from 88% in the placebo group to 12% in the TNFR5-G1,3-treated animals (p < 0.01 by Fisher's exact test). Treatments with TNR5-G1 and TNFR5-G3 in doses from 0.2 to 4.6 mg/kg were efficacious. Free plasma TNF was neutralized by all treatments, but inactive TNF/TNFR5-G1,3 complexes remained in circulation for prolonged periods. TNFR5-1,3 treatments attenuated the hemodynamic disturbances, reduced fluid requirements, and decreased the systemic IL-1 beta, IL-6, and IL-8 responses. In addition, TNFR5-G1,3 treatment shortened the granulocytopenia and reduced the loss of cellular TNF receptors from granulocytes. The decrease in fibrinogen concentrations and increase in prothrombin and partial thromboplastin times were significantly attenuated by TNFR5-G1,3 treatment. TNFR5-G1,3 treatment markedly attenuated the rise in plasma lactate concentration. Histologic studies of TNFR5-G1,3 revealed dose-dependent protection against tissue injury by Escherichia coli administration.

Protection against lethal Escherichia coli bacteremia in baboons (Papio anubis) by pretreatment with a 55-kDa TNF receptor (CD120a)-Ig fusion protein, Ro 45-2081

Fusion proteins of the human 55-kDa TNF receptor extracellular domain with hinge and C2/C3 constant domains of human IgG1 or IgG3 heavy chains were tested in a primate sepsis model. Twenty-four baboons received 4.6, or 0.2 mg/kg of TNFR5-G1,3, or placebo, before the administration of a lethal dose of live Escherichia coli. Treatment with TNFR5-G1,3 decreased 5-day mortality from 88% in the placebo group to 12% in the TNFR5-G1,3-treated animals (p < 0.01 by Fisher's exact test). Treatments with TNR5-G1 and TNFR5-G3 in doses from 0.2 to 4.6 mg/kg were efficacious. Free plasma TNF was neutralized by all treatments, but inactive TNF/TNFR5-G1,3 complexes remained in circulation for prolonged periods. TNFR5-1,3 treatments attenuated the hemodynamic disturbances, reduced fluid requirements, and decreased the systemic IL-1 beta, IL-6, and IL-8 responses. In addition, TNFR5-G1,3 treatment shortened the granulocytopenia and reduced the loss of cellular TNF receptors from granulocytes. The decrease in fibrinogen concentrations and increase in prothrombin and partial thromboplastin times were significantly attenuated by TNFR5-G1,3 treatment. TNFR5-G1,3 treatment markedly attenuated the rise in plasma lactate concentration. Histologic studies of TNFR5-G1,3 revealed dose-dependent protection against tissue injury by Escherichia coli administration.

Comparison of the nitric oxide synthase inhibitors methylarginine and aminoguanidine as prophylactic and therapeutic agents in rat adjuvant arthritis

OBJECTIVE

To compare the nitric oxide synthase (NOS) inhibitors NG-methyl-L-arginine (L-NMA) and aminoguanidine (AG) as prophylactic and therapeutic agents in rat adjuvant induced arthritis (AIA).

METHODS

Arthritis was induced in male Lewis rats by the injection of adjuvant into the base of the tail. L-NMA or AG was administered twice daily by gastric intubation starting at the time of adjuvant injection, just before the onset of clinical symptoms, or after the onset of clinical symptoms. Paw swelling, plasma fibrinogen levels and urinary NO2-/NO3- excretion were measured to assess the effect of the inhibitors on the arthritis response and whole body NO biosynthesis. Selected joints were also evaluated histopathologically. The abilities of L-NMA, AG and another NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), to inhibit NO production by chondrocytes and synoviocytes were also compared.

RESULTS

Treatment with L-NMA (400 mg/kg/day) or AG (500 mg/kg/day) reduced the urinary excretion of NO2-/NO3- to the control level. L-NMA suppressed the development of AIA when administered prophylactically; however, its antiarthritic properties declined with increasing delay of application. It was only weakly effective against established AIA. AG had neither a prophylactic nor a therapeutic antiarthritic effect. AG and L-NAME were much weaker inhibitors of NO production by chondrocytes and synoviocytes than L-NMA.

CONCLUSION

Although L-NMA completely suppresses the development of AIA when administered prophylactically, it is much less effective when administered therapeutically. Furthermore, not all inhibitors of NOS show equal prophylactic activity against AIA. In addition, NOS inhibitors may be only weakly therapeutic, or even detrimental, in established disease. These findings should be considered when evaluating NOS inhibitors as potential therapeutic agents for the treatment of established human arthritis.

Measurements of blood flow and xanthine oxidase activity during postischemic reperfusion of the large colon of ponies

To assess right colic artery blood flow and relevance of xanthine dehydrogenase/xanthine oxidase after experimentally induced strangulation obstruction and reperfusion of the colon, 5 ponies were subjected to 2.5 hours of complete ischemia of the left dorsal and ventral colons, allowed to recover from surgery, and monitored during a 48-hour reperfusion period. Five ponies were subjected to sham surgery and served as controls. All ponies had a Doppler ultrasound blood flow monitor implanted on the right colic artery near the pelvic flexure 10 to 14 days prior to the ischemic period. Colic artery blood flow was monitored prior to, during, and for 4 hours after surgery. Blood samples from the right colic artery and vein distal to the obstruction site were collected during surgery (prior to ischemia, after 1 and 2 hours of ischemia, and after 10 and 60 minutes of reperfusion) for determination of arterial and venous blood gas tensions and electrolytes. Prior to surgery, blood selenium and plasma vitamin E (alpha-tocopherol) concentrations and blood glutathione peroxidase (GPX) activity were determined to assess the status of endogenous antioxidants. Combined xanthine dehydrogenase (XDH) plus xanthine oxidase (XO) activity, and XO activity alone (nanomoles per minute per gram of tissue) were determined, using a dual-spectrophotometric technique. Xanthine dehydrogenase and oxidase activities were determined prior to ischemia, after 1 and 2 hours of ischemia, and at 1 and 48 hours after reperfusion. Median blood flow in the experimental and control groups (156 ml/min and 110 ml/min, respectively) was not statistically different before surgery, and was significantly (P < 0.02) lower in the experimental (4 ml/min) vs the control group (72.5 ml/min) during the ischemic period. Experimental ponies had significantly (P < 0.03) lower right colic artery blood flow during the 4 hours immediately after recovery from anesthesia. Significant difference was not observed in right colonic venous bicarbonate concentration between groups at any time. Median right colonic venous PCO2, pH, and standard base excess were different (P < 0.001) between groups during the ischemic period only. Median venous oxygen saturation and median venous PO2 were significantly (P < 0.001) lower in the experimental ponies at the end of 2 hours of ischemia, but were significantly (P < 0.05) increased during the reperfusion phase. Median venous potassium concentration was significantly (P < 0.01) higher in experimental ponies during the ischemic and reperfusion phases. Vitamin E and GPX values were within normal limits for all ponies.(ABSTRACT TRUNCATED AT 400 WORDS)

N-monomethyl arginine, an inhibitor of nitric oxide synthase, suppresses the development of adjuvant arthritis in rats

OBJECTIVE

To test the hypothesis that nitric oxide (NO) is involved in the pathophysiology of arthritis.

METHODS

Arthritis was induced in male Lewis rats by the injection of adjuvant into the base of the tail. The NO synthase (NOS) inhibitor, NG-monomethyl-L-arginine (L-NMA), was administered daily by the oral route for 19 days. Paw swelling, plasma fibrinogen levels, and urinary NO2/NO3 levels were measured to assess the effect of L-NMA on the arthritic response and whole-body NO production, respectively. On day 20, the ankle joints were processed for histopathologic evaluation.

RESULTS

The onset of clinical symptoms was preceded by elevated biosynthesis of NO. In a dose-dependent manner, L-NMA inhibited both NO biosynthesis and paw swelling; histopathologic changes in the ankle joints were also prevented. D-NMA had no effect on the development of arthritis, while L-arginine reversed the effects of L-NMA. Fibrinogen levels in rats with arthritis were unaffected by L-NMA.

CONCLUSION

NO is critical to the development of both the inflammatory and erosive components of adjuvant arthritis in rats. There may be a future clinical role for suitable inhibitors of NO production or activity.

Interactions between 4-HPR and diet in NMU-induced mammary tumorigenesis

The present study was designed to determine whether the chemopreventive effect of the synthetic retinoid N(4-hydroxyphenyl)retinamide (4-HPR) on mammary tumorigenesis was influenced by diet. Three diets were used: the closed-formula grain-based Wayne Lab Blox, the open-formula grain-based NIH-07, and the casein-based semipurified AIN-76A. Groups of 25 virgin female F-344 rats were fed the experimental diets beginning one week before a single injection of N-methyl-N-nitrosourea (NMU, 45 mg/kg body wt i.v.) at 50 days of age. The experimental design was as follows: Group 1, unsupplemented AIN-76A; Group 2, AIN-76A supplemented with 4-HPR starting seven days before NMU until termination (-7); Group 3, AIN-76A supplemented with 4-HPR seven days after NMU until termination (+7); Group 4, Wayne (no 4-HPR); Group 5, Wayne (4-HPR, -7); Group 6, Wayne (4-HPR, +7); Group 7, NIH-07; Group 8, NIH-07 (4-HPR, -7). 4-HPR [782 mg/kg diet (2 mM)] was given to all supplemented groups. Termination was 25 weeks post-NMU. Analysis of tumor incidence, multiplicity, and latency indicated that 1) control rats fed the AIN-76A diet exhibited significantly higher mammary tumor yields than rats fed unsupplemented natural-ingredient diets (Wayne and NIH-07) and 2) 4-HPR inhibited mammary tumor development in the two grain-based diets but enhanced tumor development in the AIN-76A diet. Animals fed the AIN-76A diet gained weight to a greater extent than those fed the Wayne or NIH-07 diets and exhibited lower levels of circulating 4-HPR.

Inhibition of rat mammary tumorigenesis by voluntary exercise

In this study, the anti-promoting effect of voluntary (wheel) exercise on 7, 12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumorigenesis was investigated. All rats were fed high fat diets (23% of calories as fat) to mimice the typical western diet. Two doses of DMBA were used to determine if the antipromoting effects of exercise were dependent on the strength of the initiating agent. In addition, tumor estrogen receptors were assayed to determined whether exercise, through an estrogen-suppressing mechanism, selects for estrogen receptor-negative tumors. Female Sprague-Dawley rats were fed a semi-purified 23% fat (corn oil) diet (AIN-76A) and, on day 50 of age administered DMBA by gavage at 5 or 10 mg/rat. Rats were then randomized into 4 groups (n = 30) as follows: 1) low DMBA/sedentary; 2) low DMBA/exercise; 3) high DMBA/-sedentary; and 4) high DMBA/exercise. Active rats were placed in wheel-cage units, which allowed voluntary access to an activity wheel for 133 (low DMBA) and 77 (high DMBA) days, respectively, Sedentary rats were placed in conventional cages. Both active groups exhibited significantly lower total tumor numbers than their sedentary controls: 75 vs 102 (low DMBA) (p < 0.05) and 90 vs 160 (high DMBA) (p < 0.001). Compared to sedentary controls, latency was significantly lengthened in the low but not the high DMBA active groups; multiplicity, in contrast, was significantly decreased in the high, but not the low DMBA exercised group. Exercise had no effect on overall tumor incidence. When segregated into exercise tertiles, total tumor active compared to the least active tertile, particularly in the high DMBA group.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of 7,12-dimethylbenz(a)anthracene-induced tumors and DNA adduct formation in the mammary glands of female Sprague-Dawley rats by the synthetic organoselenium compound, 1,4-phenylenebis(methylene)selenocyanate

We synthesized a novel organoselenium compound, 1,4-phenylenebis(methylene)selenocyanate (XSC), possessing low toxicity by comparison with inorganic Na2SeO3, and several other synthetic organoselenium compounds (K. El-Bayoumy, Cancer Res., 45: 3631-3636, 1985). We tested the effect of XSC treatment during the initiation phase on 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma formation. A semipurified high-fat diet containing 80 ppm of XSC (40 ppm as selenium) was fed to 6-wk-old virgin female Sprague-Dawley rats for 2 wk, starting 1 wk before and ending 1 wk after carcinogen treatment. At 7 wk of age, rats were given a single dose of DMBA (5 mg) in 0.2 ml of olive oil by gastric intubation; the experiment was terminated 16 wk later. The development of mammary tumors in those rats that received XSC-supplemented diets was significantly inhibited when compared with the control group (fed the same diet without XSC supplements). This was evident from tumor incidence (percentage of tumor-bearing rats, 88 versus 20) and multiplicity of tumors (mean number of tumors/rats, 3.96 versus 0.28). The finding that XSC acts as a chemopreventive agent in the DMBA mammary tumor model prompted us to examine the effect of dietary XSC on DMBA-DNA binding in both the liver and mammary tissue under conditions identical to those described above for the bioassay. Rats (four/group) were killed 6, 24, 48, and 168 h after [3H]DMBA (5 mg/rat; specific activity, 51.2 mCi/mM) administration. Liver and mammary tissue were obtained and DNA was isolated. Dietary XSC was found to inhibit total DMBA-DNA binding in the mammary tissue, but not in the liver. The most profound effect was observed at early time points, i.e., 24 to 48 h after [3H]DMBA administration. The inhibition in total binding was attributed to a reduction in the formation of the three major adducts derived from bay-region diol-epoxides of DMBA; these were identified as anti-diol-epoxide:deoxyguanosine, syn-diol-epoxide:deoxyadenosine, and anti-diol-epoxide:deoxyadenosine adducts on the basis of their chromatographic characteristics on high-pressure liquid chromatography and on a boronate affinity column. The inhibition of the DMBA-DNA binding in the target tissue provides a plausible explanation for the chemopreventive effect of XSC during the initiation stage of carcinogenesis.

Modulation of N-nitrosomethylurea-induced mammary tumor promotion by dietary fiber and fat

A test of the anticancer effects of dietary fiber was conducted using the N-nitrosomethylurea (NMU)-induced rat mammary tumor model. Starting 3 days after NMU treatment, four different groups of F344 rats (30 rats in each group) were fed as follows: Group 1 received a high-fat diet; group 2, a high-fat plus fiber diet (soft white wheat bran, 10% wt/wt); group 3, a low-fat diet; and group 4, a low-fat plus fiber diet. The rats remained on these diets for 15 weeks. Tumor incidence in group 1 was 90% compared with 66% in group 2 (P less than .001). Tumor incidence in group 3 was 63% compared with 47% in group 4 (P greater than .4). These results show that supplemental dietary fiber exerts an inhibitory effect on the promotional phase of NMU-induced mammary carcinogenesis in rats when fed a high-fat but not a low-fat diet. To test whether fiber may exert its antipromoting effect by reducing circulating estrogens, serum 17 beta-estradiol was assayed. No changes were observed in serum 17 beta-estradiol levels among the four groups, suggesting that the protective effect of fiber in this animal model is not mediated by a fiber-induced reduction of circulating 17 beta-estradiol.

Blastomycosis in a cat in lower New York State

Blastomycosis was diagnosed in a cat from lower New York State by cytologic examination of aspirates from lymph nodes. This represents a novel geographic distribution of this disease.