RESUMEN
Treatment with noncardioselective beta-adrenoceptor antagonists (e.g., 0.5% timolol or 0.5% levobunolol) is standard practice for lowering elevated intraocular pressure (IOP). However, because there are risks and side effects associated with the use of these agents, a lower, yet still effective, dose may be preferred. We gave 0.5% timolol twice daily for 30 days to 143 patients. In a double-masked, randomized fashion, we then assigned patients to continue to receive 0.5% timolol twice daily or 0.25% levobunolol twice daily for 8 weeks. The mean unmedicated baseline IOP for both groups was approximately 25 mm Hg. After 30 days of timolol pretreatment, the mean IOP in both groups decreased to approximately 19 mm Hg (p = 0.210). After the 30-day timolol pretreatment period, and subsequent randomization to either 0.5% timolol or 0.25% levobunolol treatment, there was little change in overall mean IOP (0.03 mm Hg decrease for levobunolol, 0.06 mm Hg increase for timolol; p = 0.811) from the timolol pretreatment baseline. One patient assigned to the timolol treatment group was terminated from the study due to inadequate control of IOP. We conclude that the mean IOP lowering effect of 0.25% levobunolol is equivalent to 0.5% timolol, and switching patients from twice-daily 0.5% timolol to twice-daily 0.25% levobunolol poses no significant risk of decreased ocular hypotensive efficacy.
RESUMEN
We examined the activities of Clostridium difficile toxin preparations given intragastrically to hamsters, mice, and rats. The culture filtrate from a highly toxigenic strain of C. difficile caused hemorrhage and accumulation of fluid in the small intestine and cecum, diarrhea, and death in hamsters and mice. In rats, the culture filtrate caused only a small amount of fluid accumulation and slight hemorrhage along the small intestine. When toxin A was removed from the culture filtrate, the filtrate lost its activity. Preparations of homogeneous toxin A caused a response similar to that observed after the administration of culture filtrate. Hamsters were more sensitive to toxin A than mice or rats were. When hamsters were given multiple low doses of toxin A 1 week apart at a concentration which singly caused no response, they became ill and died, indicating that the toxin may have long-term effects. High amounts of toxin B did not cause any significant response when given intragastrically, unless initially mixed with low amounts of toxin A or given to hamsters with bruised ceca. These results suggest that toxins A and B act synergistically and that the action of toxin B may occur via the tissue damage caused by toxin A.
Asunto(s)
Proteínas Bacterianas , Toxinas Bacterianas/toxicidad , Clostridium , Colitis/inducido químicamente , Enterotoxinas , Administración Oral , Animales , Toxinas Bacterianas/administración & dosificación , Enfermedades del Ciego/inducido químicamente , Cricetinae , Hemorragia Gastrointestinal/inducido químicamente , Masculino , Mesocricetus , Ratones , Ratones Endogámicos BALB C , Ratas , Ratas Endogámicas , Especificidad de la EspecieRESUMEN
Forty species of anaerobes were screened for the ability to produce an ether-extractable mutagen which is present in the feces of 15 to 20% of individuals in populations at high risk for colon cancer. This mutagen can be produced in vitro by incubating the feces of these individuals anaerobically or by supplementing anaerobic broths with methanol extracts of the feces and incubating them with a dilute fecal inoculum. Of the anaerobes screened, strains of five species of Bacteroides (B. thetaiotaomicron, B. fragilis, B. ovatus, B. uniformis, and Bacteroides group 3452A) were capable of producing five- to eightfold increases in the concentration of mutagen. For in vitro production in broth, all producers required bile and the methanol extract for feces from a person who excretes the mutagen. Mutagen production appeared to be constitutive and occurred during the stationary phase of growth. Cell-free extracts were active and produced mutagen considerably faster than did whole cells. Our observations indicate that the excretion of this mutagen by certain people is dependent on the presence of some precursor of unknown origin. The mutagen-producing species of bacteria are among the most common of the intestinal microflora and were present in mutagen excreters and nonexcreters as well.