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101.
With respect to ventral interbody fusion, rates of pseudarthrosis of up to 30% are reported. With the aim of reducing this figure, the use of dorsal fixation systems to stabilise the fused spinal units is recommended by a number of authors. The aim of these osteosynthetic procedures is to elevate the interfragmentary compression between the ventral bone block and the adjacent vertebrae. In order to measure the pressure achievable, and its local distribution, an experimental investigation involving the use of a capacitive measuring mat has been designed. The system of capacitive measurement and its application to the spine is described. The simple mode of measurement and mechanical stability, combined with high accuracy, are the specific advantages of capacitive systems of measurement. Especially in the documentation of interfragmentary pressure and pressure distribution, capacitive measuring mats are superior to comparable systems. 相似文献
102.
Carramolino L Ruiz-Gomez M Guerrero Mdel C Campuzano S Modolell J 《The EMBO journal》1982,1(10):1185-1191
The achaete-scute gene complex (AS-C) of Drosophila melanogaster is involved in the differentiation of innervated elements in the adult (chaetes) and in the embryo (central nervous system). Genetically, the AS-C is subdivided into four regions: achaete, scute α, lethal of scute, and scute β. Using a previously cloned fragment of scute DNA, we have now cloned 62 kb of wild-type DNA from the scute region. No repetitive sequences have been detected in this stretch of DNA. Of 16 scute mutants with chromosomal rearrangements studied (inversions, deletions, and translocations), nine, included genetically in scute β, have breakpoints in the cloned region. The remaining rearrangements, which genetically correspond to scute α, map outside and to the left of the cloned region. Of nine scute `point mutants' studied, eight have large DNA alterations within the cloned region. These alterations include insertions (five) and deletions (three). The DNA alterations found in both `point mutants' and rearrangements are interspersed and scattered over 40 kb. The relationship between the sites of the DNA alterations and the mutant phenotypes are discussed. 相似文献
103.
Two plasmids containing rat thyroglobulin cDNA sequences have been constructed and characterized. A plasmid with a 500-bp insert (pRT6) was isolated and identified as thyroglobulin-specific on the basis of the tissue specificity of the inserted sequence and of its ability to retain thyroglobulin mRNA on a nitrocellulose filter. The cDNA insert in pRT6 was subsequently used to screen a rat thyroid cDNA library constructed with large cDNA. A plasmid was found containing a 1700-bp insert. The polarity and the fidelity of the insert is demonstrated by S1 mapping. 相似文献
104.
Molybdenum cofactor requirement for biotin sulfoxide reduction in Escherichia coli. 总被引:18,自引:14,他引:4
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The bisC gene of Escherichia coli is tentatively identified as the structural gene for biotin sulfoxide reductase by the isolation of bisC(Ts) mutants that make thermolabile enzyme. The products of four other E. coli genes (chlA, chlB, chlE and chlG) are also needed for enzymatic activity. Mutations previously assigned to the bisA, bisB, and bisD genes belong to genes chlA, chlE, and chlG, respectively. The biotin sulfoxide reductase deficiency of a chlG, mutant is partially reversed by the addition of 10 mM molybdate to the growth medium. Mutational inactivation of the chlD gene reduces the specific activity of biotin sulfoxide reductase about twofold. This effect is reversed by the addition of 1 mM molybdate to the growth medium. The specific activity of biotin sulfoxide reductase is decreased about 30-fold by the presence of tungstate in the growth medium, an effect that has been observed previously with nitrate reductase and other molybdoenzymes. The specific activity of biotin sulfoxide reductase is not elevated in a lysate prepared by derepressing a lambda cI857 chlG prophage. Whereas biotin sulfoxide reductase prepared by sonic extraction of growing cells is almost completely dependent on the presence of a small heat-stable protein resembling thioredoxin, much of the enzyme obtained from lysates of thermoinduced lambda cI857 lysogens does not require this factor. 相似文献
105.
106.
Rhodospirillum rubrum strain F24.1 is a spontaneous revertant of nonphototrophic mutant F24 derived from wild-type strain S1. Strain F24 shows no detectable photochemical activity and contains, at most, traces of the photoreaction center polypeptides. Strain F24.1 has a phototrophic growth rate close to that of the wild-type strain (Picorel, R., del Valle-Tascón, S. and Ramírez, J.M. (1977) Arch. Biophys. Biochem. 181, 665–670) but shows little photochemical activity. Light-induced absorbance changes in the near-infrared, photoinduced EPR signals and ferricyanide-elicited absorbance changes indicate that strain F24.1 has a photoreaction center content of 7–8% as compared to strain S1. Polyacrylamide gel electrophoresis of isolated F24.1 chromatophores shows the photoreaction center polypeptides to be present in amounts compatible with this value. Photoreaction center was prepared from strain F24.1 and showed no detectable difference with that of strain S1. It is concluded that strain F24.1 photosynthesis is due entirely to its residual 7–8% of typical photoreaction center. 相似文献
107.
E del Castillo R Fuenzalida A L Rapoport J Uranga 《Acta physiologica latino americana》1978,28(4-5):179-184
Glucagon (21.5 +/- 0.23 ng/min/kg) was infused through the portal vein of normal or pancreatectomized dogs. It was observed that a dose of glucagon that produces no significant change in the glycemia of normal dogs has a very small activity in the production of glomerulopressin and does not alter glomerular filtration rate (GRF). In pancreatectomized dogs this same dose of glucagon also does not alter glycemia but it induces a large increase in the production of glomerulopressin and GFR. Our results suggest that in pancreatectomized dogs glomerulopressin production is more sensitive to glucagon infusion than in normal dogs. 相似文献
108.
109.
The selective growth of malignant cells on non-adhesive Teflon substrates is reported. Neoplastically transformed cell lines of human and murine origin proliferated on Teflon whereas similarly seeded normal non-tumorigenic cells were unable to undergo cell division and subsequent growth. This substrate should be especially useful in establishing primary cultures from human tumor material. 相似文献
110.