The selective effect of N-feruloylserotonins isolated from Leuzea carthamoides on nociception and anxiety in rats.

The effects of N-feruloylserotonins, substances isolated from the seeds of Leuzea carthamoides (WILLD.) DC., on nociception and anxiety were studied in Wistar rats. Nociceptive responses were measured using the plantar and tail-flick tests which were administered before and after swimming stress (3 min, water temperature 32 degrees C). Anxiety was evaluated using an elevated plus maze. In Experiment I, neither basal nociception nor stress-induced analgesia was influenced significantly. Separating the animals into groups based on their basal nociceptive sensitivity, either high- or low-pain threshold revealed that N-feruloylserotonins have selective effects, especially on rats with high-pain thresholds. In these animals, N-feruloylserotonins reduced the stress-induced analgesia that followed swimming stress. In Experiment II, basal nociceptive sensitivity correlated with indicators of anxiety; high-pain threshold rats were more anxious in the elevated plus maze, with less frequent visits to open arms. The opposite effect was seen in low-pain threshold rats. N-feruloylserotonins did not influence anxiety in low-pain threshold rats, although it reduced anxiety in the high-pain threshold rats as indicated by the increased ratio of open arm visit frequency compared to closed arm visit frequency in the elevated plus maze. From these results we concluded that N-feruloylserotonins have selective stress-reducing effects in stress-sensitive animals.

Resistance of gram-negative bacteria to antibiotics in large calf agglomerations.

The antibiotic resistance of E. coli, Citrobacter, Enterobacter-Klebsiella and Pseudomonas aeruginosa strains isolated from calves was tested. A high proportion of multiresistance was found even in E. coli strains isolated from newborn calves. Gram-negative bacteria isolated from animals in three large calfhouses were almost 100% resistant to ampicillin, tetracyclines and sulphonamides. Multiresistance was general and varied from 5 to 12 antibiotics among different strains. Initial high sensitivity to antibiotics which had never been used before was observed. Antibiotic resistance rapidly increased after use started. The usefulness of antibiotics in E. coli induced diarrhea is questioned and oral rehydration is appraised.

The effects of peptidoglycan, a pyrogenic constituent of gram-positive microorganisms, on the pharmacokinetics of rifampicin.

Pharmacokinetics of rifampicin (20 mg/kg orally or i.v.) was determined in calves and rabbits. Seven days later a model pyrogen was administered i.v. to the same animals and 1 hr later the rifampicin administration was repeated. The pharmacokinetic analysis of oral rifampicin was performed using a one-compartment open model with absorption. Intravenously administered rifampicin was analysed by a two-compartment intravascular model. Injection of peptidoglycan in pyrogenic doses led to a significant increase of orally applied rifampicin serum levels in both animal species. The i.v. administration of rifampicin had the same parameters in the control and peptidoglycan experiments. Daily pretreatment of rabbits with small doses of peptidoglycan induced tolerance to the pyrogenic effect. In tolerant animals we did not observe any changes of rifampicin serum levels. Elevated temperature alone was not responsible for observed pharmacokinetic changes leading to the increase of bioavailability of oral rifampicin since another pyrogenic substance (endotoxin) had an opposite effect on pharmacokinetics of previously tested drugs.

Coccidiosis in preruminating calves the effect of management and short-term treatment on the spread of infection and reinfection.

In farms with large numbers of individually-housed calves, the spread of coccidia is slow. In group pens, however, all the calves became infected within 3-4 weeks of being housed together. At the beginning of group housing no oocysts were found in the faeces of any of the calves. Sulphadimidine (SDM) was administered for 3 or 12 days at different doses and different times. Administration of the drug on Days 3-5 of group housing had no effect. Given between Days 11 and 13 or 17-19, the drug lowered (for a short period) the number of animals found to be excreting oocysts. SDM given between Days 6 and 17 kept the animals oocyst-free during that period. Within 2-3 weeks after the treatment all animals were excreting oocysts.

Changes of pharmacokinetics of trimethoprim after pretreatment with streptococcal peptidoglycan.

Trimethoprim (TMP) 10 mg.kg-1 was given orally to calves and rabbits. Two to three weeks later the animals were pretreated by i.v. Peptidoglycan (Pt) 20 micrograms.kg-1. One hour later TMP was administered as above. To other animals under otherwise identical conditions TMP was injected intravenously. The pretreatment with Peptidoglycan induced in both species a significant increase of TMP serum levels positively correlated with temperature elevation. Peptidoglycan pretreatment increased the bioavailability of TMP.

Surprises and omissions in toxicology.

The paper describes expected and unexpected results gained from studies performed decades ago, and so to say - forgotten. 1. Different bacterial toxins can induce considerable changes in pharmacokinetics and pharmacodynamics of applied drugs. To admit clinical trials, only results from healthy human volunteers are required, however. 2. Antagonists to the toxicity of bacterial toxins in general have to be administered prior to the toxin. However, adenosine triphosphate (ATP) is effective also when applied after toxins. ATP is "in" again in contemporary research. 3. A controlled clinical trial revealed substantial differences between the D- and D,L-form of cycloserin. 4. The antimetabolite 6-azauracil riboside and eventually its triacetate derivative was claimed to possess antitumor properties. However, a controlled clinical trial did not confirm its potency in this aspect. On the other hand, the tolerance was excellent. This finding encouraged clinical trials in psoriasis, a disease of autoimmune etiology. Moreover, beneficial effects and tolerance of the compound was described in herpes zoster and even in smallpox. On the basis of these results a controlled clinical trial in rheumatoid arthritis, also judged to be an autoimmune disease, was started. Because of early high toxicity, the study was discontinued. 5. High doses of the compound induce ocular lesions in animals. The above examples justify the titel of this paper.

[Vaccination of cattle against trichophytosis in the prevention and control of dermatophytic zoonoses]. / Zkusenosti s vakcinací skotu proti trichofytóze pri prevenci a tlumení dermatofytických zoonóz.

The results of a four-year study of the occurrence of trichophytosis in some cattle stocks in the Pardubice district are presented. The monoetiological nature of this mycosis is documented; this mycosis can be successfully controlled by vaccination. Experiments demonstrated a good activity of antigens which were included in commercial vaccines. The evaluation of the antibody reaction in test rabbits and in vaccinated and spontaneously infected cattle was subjected to critical analysis. However, the main point of the whole study is a general evaluation of the possibilities and limitations of cattle vaccination against trichophytosis as ensues from literary data and from the authors' experience. The results indicate that in permanent application of all the hitherto used preventive and repressive methods a technically correct active immunization of cattle means the best contribution to the control of trichophytosis. The discussion deals with the theoretical problems of the nature and duration of immunity to these diseases and with the choice of the best vaccines and vaccination procedures.

[Effect of tylosin in pigs]. / Ucinek tylosinu u prasat

The effect of tylosine and sulphadimidine, chlortetracycline, and bacitracin in feed was studied in 1275 piglets from 120 litters; the values obtained were compared with the control group given no antibiotics. Three Tylan injections were applied to a half of the animals on the 2nd, 5th, and 28th day after birth. The Tylan program did not lead to any significant reduction of piglet mortality before the 50th day of life. In neither of the groups did Tylan injections reduce mortality at the level of statistical significance. From the age of 56 days, the Tylan-application program provides statistically significant weight gains, as compared with other groups. The group with Czechoslovak antibiotics had the same weight as the group fed without antibiotics. The occurrence of pathological and anatomic findings on lungs showed no statistically significant differences in the two groups. The presence of tylosine in blood could not be ascertained after the oral application of even much higher doses than those used in the Tylan-application program. Small incidence of rhinitis does not allow for drawing any conclusions concerning the effects of Tylan.