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排序方式: 共有239条查询结果,搜索用时 15 毫秒
1.
Preservation of All Chordae Tendineae and Papillary Muscle During Mitral Valve Replacement with a Tilting Disc Valve 总被引:1,自引:0,他引:1
HAROLD L. FEIKES M.D. JAMES B. DAUGHARTHY M.D. JESSE E. PERRY M.D. JOHN H. BELL M.D. ROBERT E. HIEB M.D. GILBERT H. JOHNSON P.A.-C. 《Journal of cardiac surgery》1990,5(2):81-85
Mitral valve replacement was performed in 21 patients using a surgical technique that preserves the entire papillary muscle and chordal apparatus. With this technique, the anterior mitral leaflet is split from the center of the free edge toward the annulus. Bilateral incisions are made from the proximal end of this split to the two mitral commissures, detaching the anterior leaflet from the annulus. These two halves of the leaflet, with all chordae intact (corresponding to the anterolateral and posteromedial papillary muscles), are judiciously trimmed to remove areas of leaflet untethered by chordae tendineae and (when necessary) fibrous thickening; then swung posteriorly and sutured to the posterior mitral annulus using mattress sutures with pledgets. This surgical technique is expected to favor the preservation of left ventricular function and avoid occurrence of irreversible left ventricular dilation/dysfunction, and has been used successfully for calcific and degenerative etiologies, using both tilting disc valves and porcine bioprostheses. It is especially useful in the implantation of tilting disc and bileaflet mechanical prostheses because anterior subvalvular chordae tissue may interfere with the disc excursion and relocated to the posterior leaflet annulus. 相似文献
2.
HAROLD D. HOLDER ROBERT F. SALTZ JOEL W. GRUBE ROBERT B. VOAS PAUL J. GRUENEWALD ANDREW J. TRENO 《Addiction (Abingdon, England)》1997,92(Z2):S155-S171
The 5-year “Preventing Alcohol Trauma: A Community Trial” project in the United States was designed to reduce alcohol-involved injuries and death in three experimental communities. The project consisted of five mutually reinforcing components: (1) Community Mobilization Component to develop community organization and support, (2) Responsible Beverage Service Component to establish standards for servers and owner/managers of on-premise alcohol outlets to reduce their risk of having intoxicated and/or underage customers in bars and restaurants, (3) Drinking and Driving Component to increase local DWI enforcement efficiency and to increase the actual and perceived risk that drinking drivers would be detected, (4) Underage Drinking Component to reduce retail availability of alcohol to minors, and (5) Alcohol Access Component to use local zoning powers and other municipal controls of outlet number and density to reduce the availability of alcohol. This paper gives an overview of the rationale and causal model, the research design and outline of each intervention component for the entire prevention trial. 相似文献
3.
Comparison of computer-assisted learning with tutorial teaching in a group of first-year dental students 总被引:1,自引:0,他引:1
Two identical groups of first-year dental students were instructed in the pathology of dental caries and periodontitis using computer-assisted learning (CAL) or tutorial teaching (TT). A cross-over arrangement, in which the first group was taught about dental caries by CAL and periodontitis by TT and the second group in the reverse order, allowed comparison of the two methods. The comparison included a knowledge test and completion of a questionnaire. CAL and TT were equally effective as far as acquisition of knowledge was concerned. Students felt pressurized with CAL and had problems with note-taking. They liked a teacher to be present. Nevertheless, CAL was an acceptable method of instruction and was more economical, in terms of staff involvement, than TT. 相似文献
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5.
Oral bropirimine (an immunomodulator shown to induce interferon)was administered to timed-pregnant Sprague-Dawley rats in fiveexperiments utilizing several different dosing schedules. Concentrationsof 100, 200, and 400 mg/kg of bropirimine were used. Interferonlevels were determined in maternal serum, spleen, and wholeembryo extracts and uterine contents were evaluated for survivalof the embryos. Maternal toxicity occurred in all experimentsas evidenced by dose-related decreases in body weight duringthe first 24 hr postdosing. Hematoxicology analyses of maternalserum revealed significant decreases in urea nitrogen, potassium,and albumin, along with increases in aspartate transaminase,alanine transaminase, and total bilirubin, in bropirimine-treateddams as compared to the vehicle controls. In addition, the meansfor maternal thymus weight decreased while the means for spleenweight increased with increasing concentration of bropirimine.As compared to the vehicle controls, interferon titers werehigh in maternal serum, maternal spleen, and, to a lesser extent,whole embryos, 2 hr postdosing, but had decreased or were belowdetectable levels 24 hr postdosing. Embryolethality was pronounced(increases in pre- and postimplantational loss) after a singledose (Gestation Day 3, 4, 5, 8, 9, or 10) of bropirimine, aswell as after 7 or 8 consecutive days (Gestation Days 612or 613) of treatment. Although embryotoxicity never occurredin these experiments in the absence of pronounced maternal toxicity,the pregnant dams never died as the result of bropirimine treatment,whereas the embryos frequently failed to survive. 相似文献
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7.
abstract — More than 80 specimens of enamel from 20 ground sections of eight teeth showing severe dental fluorosis have been examined in the transmission electron microscope. The study has shown that the prisms have normal size and form, but are surrounded by large periprismatic gaps. The individual crystals commonly appear in cross sections as regular, flattened hexagons with an average width of 91 nm and average thickness of 45 nm. Particularly in the tail regions and at prism peripheries, extensive intercrystalline spaces were found. The crystal lattice demonstrated a spacing of 0.82 nm. Demineralization of thin sections with PTA showed a preferential dissolution of the crystal centers. Based on the ultra-structural observations it is proposed that the hypomineralized regions of fluorosed enamel are produced by an arrest of enamel maturation, possibly due to toxic damage to the ameloblasts in the absorptive or maturative phase of their life cycle. 相似文献
8.
BENIGN ORGASMIC CEPHALGIA 总被引:3,自引:0,他引:3
GEORGE W. PAULSON M.D. Neurologist HAROLD L. KLAWANS JR. M.D. Associate Professor 《Headache》1974,13(4):181-187
9.
YVONNE PATERSON EVELYN R. STIMSON DAVID J. EVANS SYDNEY J. LEACH HAROLD A. SCHERAGA 《Chemical biology & drug design》1982,20(5):468-480
The N-acetyl(Aib)nN' -methylamides (with n= 1, 2 and 3) and the N-acetyl-(Aib)3 methyl ester have been synthesized using an oxazolone procedure. An experimental conformational analysis of this series of oligomers has been carried out in water, DMSO-d6 and CDCI3 using n.m.r. techniques, and in chloroform using i.r. spectroscopy. Deuterium exchange rates of amide protons in DMSO-d6 and the rates of change of these proton chemical shifts with temperature in water, DMSO-d6 and CDCI3 indicate that the oligomeric N'-methylamides adopt conformations that have no hydrogen bonds when n = 1, one hydrogen bond when n = 2, and two hydrogen bonds when n = 3, and that Ac(Aib)3OMe has a conformation with one hydrogen bond. An analysis of the N-H stretching region of the i.r. spectra of these compounds in CHCI3 also suggests the existence of these conformational states. These data imply that the peptides adopt the 310-helical and not the α-helical conformation in solution. This conclusion supports the hypothesis that the Aib residue has asymmetric geometry at the Cα atom in solution, similar to that reported in the literature for the crystalline state. 相似文献
10.