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61.
The glutamatergic (NMDA) and cholinergic neurotransmitter systems have been extensively implicated as neurochemical mediators of learning processes. These two systems may differentially affect learning; for example, although both the cholinergic antagonist scopolamine and the NMDA antagonist MK-801 reduced overall accuracy of rats in a 3-member repeated acquisition paradigm, the nature of the underlying error patterns produced by the two drugs differed significantly: rats administered scopolamine produced a pattern of skipping errors, while administration of MK-801 predominantly increased perseverative errors (Cohn et al., 1992). The present experiment extended that study to examine whether a more complex task, i.e. a 4-member repeated acquisition paradigm, would alter the nature of the error patterns resulting from administration of each drug, and whether NMDA itself would increase accuracy on the repeated acquisition paradigm. MK-801 (0.05-0.3mg/kg i.p.) significantly decreased overall accuracy in a dose-dependent manner, and the rats produced a pattern of errors similar, although not identical to, that noted in the 3-member paradigm, including perseverative errors early in the sequence, but additional skipping errors at later points in the sequence. MK-801 dramatically decreased correct initiation of a sequence following an error at any point in the sequence. NMDA (10.0-30.0mg/kg) itself did not facilitate sequence acquisition, i.e. it did not affect overall accuracy. However, it was the only drug to increase the frequency of correctly reinitiating a sequence following an incorrect first or an incorrect second sequence member. Like MK-801, scopolamine (0.5-3.0mg/kg i.p.) also produced a decline in overall accuracy which was again achieved primarily through increased skipping errors. Scopolamine did not, however, interfere with correctly reinitiating a sequence either after successful completion of a sequence, or after an error. These findings suggest that cholinergic and glutamatergic compounds exert their effects on learning through different behavioral mechanisms. 相似文献
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D J Schnell D L Higgins R M Wilson G Goldbaum D L Cohn R J Wolitski 《American journal of public health》1992,82(12):1675-1676
We evaluated disclosure of human immunodeficiency virus (HIV) antibody status to a main sex partner and the impact on the relationship in men who have sex with men and who are enrolled in the Acquired Immunodeficiency Syndrome (AIDS) Community Demonstration Projects cohorts. Eighty-nine percent of both seronegative and seropositive men disclosed the results to their main sex partner. Seventy percent of the seronegative men and 82% of the seropositive men who did so reported that the relationship remained "as strong as ever" after 6 months. Most men who did not disclose their test results to their main partner reported being "single" after 6 months. 相似文献
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L H Cohn 《The Annals of thoracic surgery》1991,51(4):683-4; discussion 684-5
The Hancock porcine xenograft valve was the first commercially prepared, quality-controlled tissue valve. The National Institutes of Health group began implantation of this valve in 1970 and reported on the first 5 years of their results, which was one of the longest follow-ups of that valve at that particular time. Since then there have been a number of centers that have had long-term experience with thousands of these valves. In retrospect, it is now clear that some of the conclusions made by the National Institutes of Health group have not come to pass, such as this valve being the "valve of choice" for all patients. "Valve of choice" is a relative term and may be one valve for one patient and another valve for another patient. This report was important in bringing together some of the first medium-term data and pointing out that, even in this valve, there was some small degree of thromboembolism. The paper also provided a historical look at the methods of data analysis that were in use in the early 1970s compared with those now used in 1991. Actuarial curves were not yet commonly used, nor were percent/patient-year linearized results. Valve types were mixed as well. Hemodynamic data, always a strong point of National Institutes of Health data analysis, were excellent. The use of this valve became a fairly standard device and has been retrospectively analyzed by a number of centers, suggesting that now it is better used in the older patient or in patients who cannot take warfarin sodium.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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David E. Cohn MD William A. Peters III MD Howard G. Muntz MD Rae Wu MD Benjamin E. Greer MD Hisham K. Tamimi MD Charles W. Drescher MD Michael R. Smith MD Joseph L. Yon MD Rodney Schmidt MD PhD Barbara A. Goff MD 《American journal of obstetrics and gynecology》1998,178(6):1131-1137
OBJECTIVE: We set out to evaluate the prognostic factors in cervical adenocarcinoma metastatic to lymph nodes. STUDY DESIGN: We performed a retrospective review of 40 patients with cervical adenocarcinoma and lymph node metastasis from 1976 to 1996. RESULTS: Thirty-four patients had adenocarcinoma, and six had adenosquamous carcinoma. Median survival was 50 months. The median survival for patients with stage I disease was 69 months. Stage at diagnosis, treatment with radical hysterectomy, and receiving adjuvant therapy were associated with prolonged survival. A trend toward improved survival was noted with the use of concurrent radiation and chemotherapy as an adjuvant therapy. CONCLUSIONS: Adenocarcinoma metastatic to the lymph nodes does not have a uniformly poor prognosis, especially with early-stage disease. Improved survival was observed with the use of adjuvant therapy, specifically the use of combined chemotherapy and radiation after radical hysterectomy. The optimal therapy in this setting is yet to be determined. (Am J Obstet Gynecol 1998;178:1131-7.) 相似文献
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