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Helen M. Blau Cecelia Webster Choy-Pik Chiu Susan Guttman Frances Chandler 《Experimental cell research》1983,144(2):495-503
The interpretation of the majority of studies of Duchenne muscular dystrophy (DMD) has been complicated by the heterogeneous composition of the cultures used. In addition to muscle cells, muscle tissue contains adipocytes and fibroblasts and the proportion of these cell types varies, especially in disease states. To overcome this problem we developed culture conditions which permitted isolation and characterization of pure populations of clonally derived human muscle cells [1, 2]. Here we report the successful application of these methods to muscle cells from biopsies of individuals with diagnosed DMD. The normal and mutant human muscle cells were used in experiments of muscle differentiation in the same manner as cell lines. Frozen-stored cells were thawed, plated in a series of replicate plates, and allowed to differentiate under similar culture conditions. Yet, in contrast with cell lines, the cells were karyotypically normal, not altered by adaptation to long-term culture, and had a finite lifespan. We have systematically analysed specific properties of the normal and DMD muscle cells which differentiated in culture. The kinetics and extent of myoblast fusion, myotube morphology, and the accumulation and distribution of membrane acetylcholine receptors were monitored. In addition, the isozyme composition of creatine kinase and its intracellular and extracellular distribution were determined. Our results indicate that DMD muscle cells are fully capable of initiating myogenesis in culture and do not differ from normal muscle in several important parameters of differentiation. 相似文献
6.
An in vitro perfusion system at 37 degrees C for the assessment of rabbit kidney function is described. The purpose of this assay system is to evaluate the effects of cryobiological manipulation on kidney function. The effect of the colloids dextran (MW = 70,000, 80,000, and 180,000) in the perfusate at 110 mm Hg were compared to a reduced perfusion pressure, colloid-free perfusate. Better function was obtained at lower perfusion pressure with the colloid-free perfusate. Less damage was noted histologically on light and electron microscopy. Investigation of energy substrates on rabbit kidney function demonstrated that butyrate, or lactate, in addition to glucose resulted in increased sodium and glucose reabsorption over glucose alone. Substrate-free perfused kidneys exhibited depressed Na transport. Lactate, and to some extent butyrate, decreased net glucose utilization. An alpha-adrenergic blocking agent, isoxsuprine, in the initial flush solution did not appear to be beneficial. An increase of perfusion pressure from 50 to 75 mm Hg resulted in an increase in GFR. Tubular function was enhanced by inclusion of small amounts of BSA in the perfusate. 相似文献
7.
Summary
Drosophila melanogaster males heterozygous for the second chromosome locus Segregation Distorter preferentially transmit this chromosome to their progeny due to a dysfunctioning of SD
+-bearing sperm. SD males with a normal sex chromosome constitution produce more females than males among SD
+ progeny. This report shows that this unequal recovery of sexes is enhanced from XY/Y; SD/SD
+ males and enhanced still further from XY/O; SD/SD
+ males. It is argued that the probability that a SD
+-bearing sperm will dysfunction is related to its sex chromsome complement, with the relative probabilities of dysfunction ranked O>
Y>
X>
XY. It is shown that a modified probit analysis accounts for the relationship between sex ratio and second chromosome segregation frequency for all paternal genotypes. Finally, SD/SD
+ males show no increase in sex chromosome nondisjunction with respect to a control.R. E. Denell was supported by U.S.P.H.S. Training Grant No. GM00337 and by a U.S.P.H.S. Postdoctoral Fellowship; George L. Gabor Miklos was supported by A.E.C. Contract No. AT (04-3)-34 PA150. 相似文献
8.
A population of Bufo americanus from southwestern Ohio exhibited an extreme degree of transferrin and albumin polymorphism. One hundred and eighty-five individuals were collected from this population, and their transferrin and albumin phenotypes were determined by vertical acrylamide gel electrophoresis. Thirteen transferrin alleles were present in 36 phenotypes, and 11 albumin alleles were present in 29 phenotypes. A deficiency of heterozygotes occurred at both protein loci. The possible mechanisms responsible for the polymorphism and deficiency of heterozygotes are discussed.This work was supported by grants from the following agencies to the Senior author: NSF GB23601, Society of the Sigma Xi, and the American Philosophical Society. Miami University contributed the computer and audiovisual services. 相似文献
9.
Effect of Temperature on the Potential and Current Thresholds of Axon Membrane 总被引:1,自引:1,他引:0 下载免费PDF全文
Rita Guttman with the technical assistance of Ben Sandler 《The Journal of general physiology》1962,46(2):257-266
The effect of temperature on the potential and current thresholds of the squid giant axon membrane was measured with gross external electrodes. A central segment of the axon, 0.8 mm long and in sea water, was isolated by flowing low conductance, isoosmotic sucrose solution on each side; both ends were depolarized in isoosmotic KCl. Measured biphasic square wave currents at five cycles per second were applied between one end of the nerve and the membrane of the central segment. The membrane potential was recorded between the central sea water and the other depolarized end. The recorded potentials are developed only across the membrane impedance. Threshold current values ranged from 3.2 µa at 267deg;C to 1 µa at 7.5°C. Threshold potential values ranged from 50 mv at 26°C to 6 mv at 7.5°C. The mean Q10 of threshold current was 2.3 (SD = 0.2), while the Q10 for threshold potentials was 2.0 (SD = 0.1). 相似文献
10.
Selection at linked sites has important consequences for the properties of neutral variation and for tests of the predictions
of the neutral theory of molecular evolution. We review the theory of the effect of adaptive gene substitutions on neutral
variability at linked sites (hitchhiking or selective sweeps) and discuss theoretical results on the effect of selection against
deleterious alleles on variation at linked sites (background selection). InDrosophila melanogaster there is a clear relation between the frequency of recombination in a given region of the chromosome and the amount of natural
variability in that region. Attempts to predict this relation have given rise to models of selective sweeps and background
selection. We describe possible methods of discriminating between these models, and also discuss the probable strong influence
of selective sweeps on variation in largely nonrecombining genomes, with particular reference toEscherichia coll. Finally we present some unresolved questions and possible directions for future research. 相似文献