Effect of tetracyclines and 4-epiderivatives on the ureter

1. The effect of tetracyclines on the isolated dog ureter is dependent on: (a) the tetracyclines used-mepicycline and doxycycline antagonizing, and tetracycline and rolitetracycline increasing the contractor action of barium chloride; (b) the percentage of 4-epiderivatives in the tetracyclines used-the higher the epiderivative concentration, the smaller the effect of mepicycline or doxycycline, and the greater the action of tetracycline or rolitetracycline.2. In vivo the addition of the antibiotics into the renal pelvis shows no significant differences between the various tetracyclines or different 4-epiderivative concentrations on the intra-ureteral flow of the dog or guinea-pig.3. Intravenous injection of mepicycline or doxycycline does not induce a significant change in the intra-ureteral flow, while intravenous administration of tetracycline or rolitetracycline produces a triphasic response: (a) a marked decrease of the intra-ureteral flow for a few minutes; (b) a return to the control condition for 30-60 min; and (c) a lesser but persistent decrease in flow for 60-120 minutes. In the first phase the ureteral smooth muscle is directly affected by the antibiotics circulating in the blood, while in the third phase the tetracyclines act via the intra-ureteral mucosa.4. Neurogenic effects on the ureter-bladder junction in vivo are not affected by the tetracyclines tested.

The effect of an oestrogenic steroid on the primary antibody response under different hormonal environments

The effect of mestranol at 2 dose levels was studied on the antibody response of intact mice as well as on ovariectomized mice, adrenalectomized mice, and adrenalectomized and ovariectomized mice. Tetanus toxoid was used as the immunogen of choice. The results revealed that mestranol produced a dose related enhancement in the circulating levels of antitetanus antibodies in intact animals and to a lesser extent in ovariectomized animals. Adrenalectomy enhanced antibody production only marginally, and the results were not statistically significant. In animals from which both the ovaries and adrenals had been removed, the antibody levels showed a definite increase. Thus mestranol which is less oestrogenic than substituted 17β-oestradiol is capable of enhancing the immunological response in mice.

Chromogenesis variations in strains of Pseudomonas aeruginosa growing in presence of chloramphenicol and oxytetracycline

The effects of subinhibitory doses of chloramphenicol and oxytetracycline on chromogen formation by normal and antibiotic-resistant Pseudomonas aeruginosa strains were studied. Partial or total inhibitions of the phenazine compounds were observed while the oxyphenoxazone synthesis appeared increased. In addition, several molecular modifications, presumably as a physiological response against the damaging drugs, were detected.

The effect of medicated feed on the nasal microflora and weight gain of pigs

Antimicrobial agents were added to the feed of swine for three weeks to determine the interrelationships of potentially pathogenic agents in the nasal tract, turbinate atrophy and weight gains. Bordetella bronchiseptica was not isolated from the groups fed the combination of chlortetracycline, penicillin and sulfamethazine. B. bronchiseptica was found in some pigs after the feeding trail, but this organism was not significantly associated with turbinate atrophy at the time of slaughter.Mycoplasma hyorhinis was not found in the nasal passages of the pigs that received feed containing high concentration chlortetracycline but was found in pigs that received other diets. Hemophilus suis was not significantly reduced by any of the treatments used. The organisms studied in the pigs were not isolated from the personnel handling the pigs.

Influence of antibiotics or certain intestinal bacteria on orally administered Candida albicans in germ-free and conventional mice

Candida albicans, administered by gastric intubation, persisted in the gastrointestinal tract of gnotobiotic mice for long periods but was eliminated within a relatively short period of time in pathogen-free mice. Oxytetracycline administered by mouth had no reproducible effect on the persistence of C. albicans in the gastrointestinal tract of either germ-free or pathogen-free mice. Prolonged administration of streptomycin extended the time that C. albicans could be recovered from feces of pathogen-free mice when compared to mice not receiving the antibiotic or those receiving a single large dose. There was a brief interval of time during which C. albicans could not be recovered from the feces of gnotobiotic mice contaminated with certain intestinal bacteria, but eventually all mice began to shed the fungus again. C. albicans administered by mouth was not pathogenic for germ-free or pathogen-free mice. It can be concluded from these findings that mice do not possess an innate resistance to C. albicans but that pathogen-free mice do possess some ecological mechanism which prevents establishment of the fungus in their gastrointestinal tract. The reason for the difference in colonization of C. albicans in germ-free or gnotobiotic mice and pathogen-free mice was not determined.