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41.
Restriction endonucleases   总被引:5,自引:0,他引:5  
  相似文献   
42.
Mutant strains of Rhizobium japonicum that were unable to allow the Corsoy cultivar of soybean to reduce acetylene or fix N2 were isolated. These strains grow as well as the wild type in a variety of media. Mutant strains SM1 and SM2 did not form nodules on the host plant; however, they reduced acetylene in the nonsymbiotic assay. Strains SM3 and SM4 produced nodules that did not have the characteristic pink pigment caused by leghemoglobin. The nodules formed by these strains also were small. One mutant strain, SM5, produced large pink nodules. The lesion in this strain seems to be in the gene that specifies nitrogenase component II.  相似文献   
43.
This study provides a map of variations of families and some of the core relationships between types of family and the mental health of children. Family types in a poor, black urban community were defined in terms of the adults present at home. The resulting taxonomy is based on two populations: half of the community's 1964 first-grade children and families and the entire 1966 first-grade children and families. Eighty-six family types were found, falling into ten major classes. Family type was found to be strongly related over time to the child's social adaptational status (SAS) and his or her psychological well-being. The results suggest that (1) mother alone families entail the highest risk in terms of social maladaptation and psychological well-being of the child; (2) the presence of certain second adults has important ameliorative functions--mother/grandmother families being nearly as effective as mother/father families, with mother/stepfather families similar to mother alone in regard to risk; and (3) the absence of the father was less important than the aloneness of the mother in relation to risk.  相似文献   
44.
Simultaneous measurement of cardiac output distribution with 86Rubidium and 57Cobalt-tagged microspheres in rats implanted with liver tumors by intraportal injection of sarcoma cells enables quantitation of arterial and portal tumor circulation. The portal circulation was found to be increased in small tumors as compared to the liver, but as the tumor grew there was a decrease in the portal tumor circulation. When the tumor growth became massive even the total liver circulation was reduced, as measured with 133Xenon wash-out. All the tumors had increased arterial circulation. This arterial hyperperfusion was changed into ischemia when the liver artery was occluded through embolization with degradable microspheres.  相似文献   
45.
Pentobarbital pellet implantation increased more than 200% the ED50 dose of pentobarbital required to induce loss of the righting reflex within 2 min of i.p. injection and increased the onset of barbital-induced sleep. Both tests of functional barbiturate tolerance were blocked by the intraventricular injection of cycloheximide. The effects of acute (45 mg/kg i.p.) and chronic (pellet implantation) pentobarbital treatment on the incorporation of 3/-lysine into the protein of various subcellular fractions of the cortex and subcortex were studied. In the subcortex, chronic pentobarbital treatment significantly stimulated protein synthesis 40-50% in the microsomal, soluble and mitochondrial fractions. Both acute and chronic pentobarbital treatments significantly increased (3H-lys)-protein accumulation in a fraction of synaptic plasma membranes derived from a population of nerve ending particles (NEP) enriched in gamma-aminobutyric acid (GABA). The possible significance of these data to pentobarbital tolerance and dependence development is discussed.  相似文献   
46.
We have reported our experience with splenectomy in fifty patients less than fourteen years old. The indications, results, and complications were enumerated. These data were then correlated with the recent literature regarding pediatric splenctomy. Of special note is the problem of immunologic incompetency associated with splenectomy in the patients less than five years old.  相似文献   
47.
Whole ovaries from 16-day fetal mice were cultured for 6 to 20 days and then transplanted to the kidneys of ovariectomized adult mice where they remained for one to four weeks. After three weeks in the host's kidneys, many follicles developed within the transplants and became vesiculated. Many of the oocytes within these follicles had formed the first metaphase spindle of meiosis and several had completed the first polar body. Host mice bearing transplants that contained vesiculated follicles showed uterine stimulation and keratinization of their vaginae. However, ovaries that had been in culture for more than ten days before transplantation showed a limited response to the gonadotropins and never matured sufficiently to stimulate the host's reproductive tract. No ovulations occurred in any of the transplants.  相似文献   
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In order to establish criteria for elective use of the intra-aortic balloon pump (IABP) in patients having cardiac surgery, we conducted a retrospective study of 43 patients who required counterpulsation, because of inability to be weaned from cardiopulmonary bypass, between May, 1972, and June, 1974. Patients in cardiogenic shock preoperatively were excluded. The 43 patients included 23 (Group A) who had severe preoperative left ventricular dysfunction with a mean cardiac index less than 1.8 L. per minute per square meter, ejection fraction less than 30 per cent, and end-diastolic pressure greater than 22 mm. Hg; 20 patients (Group B) had a combination of moderate cardiac dysfunction (cardiac index less than 2.2, ejection fraction less than 40, end-diastolic pressure less than 18) in the presence of acute infarction or severe aortic stenosis (gradient greater than 80 mm. Hg) with or without coronary disease. An inverse relationship was noted between survival and delay from completion of operation to the use of 1ABP. Thirty-two of 43 patients were weaned off bypass and were balloon assisted for 12 to 96 hours postoperatively; 25 patients were discharged (58 per cent). In Subgroup A, 14 of 23 (60 per cent) and, in Subgroup B, 9 of 20 (45 per cent) were long-term survivors. Based on these findings, 45 patients were operated upon between June, 1974, and December, 1975, with elective use of 1ABP and were assessed by serial hemodynamic studies. Sixteen had severe preoperative left ventricular dysfunction similar to Subgroup A and 29 had moderate dysfunction in combination with pathology similar to Subgroup B. Fifteen of these patients were hemodynamically unstable at time of arrival in the operating room; 1ABP was inserted under local anesthesia. Thirty-nine patients (87 per cent) were weaned off bypass and were hospital survivors. In Subgroup A, 13 of 16 (81 per cent) and, in Group B, 21 of 29 (72 per cent) were long-term survivors. Criteria for elective use of 1ABP in cardiac surgery should include severe preoperative left ventricular dysfunction or a combination of moderate dysfunction with coronary or valvular pathology. Elective 1ABP improves the survival with trivial iatrogenic morbidity.  相似文献   
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