PubMed · 10028577
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
W Lewis. 1999-01-02. Declining risk from beef on the bone.. https://pubmed.ncbi.nlm.nih.gov/10028577/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Cataract prevalence increases with age. As the world's population ages, cataract-induced visual dysfunction and blindness is on the increase. This is a significant global problem. The challenges are to prevent or delay cataract formation, and treat that which does occur. Genetic and environmental factors contribute to cataract formation. However, reducing ocular exposure to UV-B radiation and stopping smoking are the only interventions that can reduce factors that affect the risk of cataract. The cure for cataract is surgery, but this is not equally available to all, and the surgery which is available does not produce equal outcomes. Readily available surgical services capable of delivering good vision rehabilitation must be acceptable and accessible to all in need, no matter what their circumstances. To establish and sustain these services requires comprehensive strategies that go beyond a narrow focus on surgical technique. There must be changes in government priorities, population education, and an integrated approach to surgical and management training. This approach must include supply of start-up capital equipment, establishment of surgical audit, resupply of consumables, and cost-recovery mechanisms. Considerable innovation is required. Nowhere is this more evident than in the pursuit of secure funding for ongoing services.
This study investigated the effects of the NMDA receptor antagonist MK-801 on the development of morphine dependence in 7-, 14-, and 21-day-old rat pups. For 6.5 days, starting at 1, 8, or 15 days of age, rats were pretreated with MK-801 (0.03 or 0.1 mg/kg, bid) or saline; 15 min later, morphine sulfate (10 mg/kg) or saline was injected to induce opiate dependence. On the afternoon of the seventh day, pups were injected with MK-801 (0.1 mg/kg) or saline and 15 min later with naltrexone (1 mg/kg) to precipitate withdrawal. Pups were then placed in a warm chamber with the litter and their behavior scan-sampled every 15 sec for a total of 15 min. MK-801 failed to inhibit morphine withdrawal in the 7-day-old rat, but did attenuate the development of morphine dependence in both the 14- and 21-day-old rats. These results suggest that the NMDA receptor is not functionally active in opiate withdrawal until around the second to third week of postnatal life in the rat and that there exists a transition period for the NMDA receptor to play a role in the development of opiate dependence and withdrawal.
Significant sex differences exist among cases of bladder cancer in humans as well as in experimental animals such as rats. Aromatic amines such as benzidine and 2-naphthylamine are known to induce bladder cancer. These carcinogenic amines are activated to genotoxic substances by cytochrome P 450 CYP4B1, which is present in bladder mucosa. In this study, regulation of CYP4B1 was investigated to elucidate sex difference in bladder carcinogenesis. Competitive reverse transcription-polymerase chain reaction was used to investigate the expression of rat CYP4B1 mRNA occurring in small amounts of tissue such as bladder tissue. Expression of CYP4B1 in the bladder of male rats increased with development but not in that of female rats. Moreover, mature male rats exhibited higher expression of CYP4B1 in the bladder than did mature female rats. Castration of male rats decreased CYP4B1 levels and treatment with testosterone led to a partial recovery of CYP4B1 levels. These results indicate that CYP4B1 levels in the rat bladder are partly regulated by androgens. Furthermore, the present findings suggest that the sex difference observed in bladder carcinogenesis was due to sex-different expression of CYP4B1 in bladder tissue.