ISSN:0148-7299    

DOI:10.1002/ajmg.1320250402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0148-7299    

DOI:10.1002/ajmg.1320250403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0148-7299    

DOI:10.1002/ajmg.1320250404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe initial formation of skeletal muscle fibers is accompanied by the expression of muscle‐type actin and myosin genes. During subsequent maturation of muscle fibers in vivo, developmental changes in the fetal/adult isoforms of these proteins occur. Skeletal muscle‐specific transcripts coding for different myosin heavy chains accumulate sequentially both in vivo and in vitro. A genetic analysis demonstrates that these genes are clustered, implicating cis‐acting regulatory factors. In contrast, actin and myosin light chain genes are dispersed in the mouse genome. These gene families show a different developmental “strategy”: Genes expressed in adult cardiac tissue are coexpressed with the corresponding skeletal muscle sequence during fetal development. This phenomenon also occurs in adult tissue. Under conditions of cardiac overload, adult rat hearts accumulate skeletal actin mRNA and cardiac actin transcripts. In some mouse lines, a mutant cardiac actin gene locus is present. The presence of a second active upstream promoter at this locus depresses transcription of the bona fide gene, resulting in low levels of mature cardiac actin mRNA. In this situation skeletal actin gene transcripts accumulate. Genes expressed in the same fetal or adult muscle phenotype are not linked, suggesting that their coexpression is regulated by transacting factors. The promoter regions of such genes in the mouse have no common characteristics of primary structure with the exception of an ElA‐type enhancer core sequence, which has a conserved 5′ flanking element, seen for actin and myosin light chain genes. Reintroduction of these promoter regions into muscle cells provides a functional test for such potential regulat

ISSN:0148-7299    

DOI:10.1002/ajmg.1320250405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractSix glycogen storage diseases (resulting from deficiencies of acid maltase, phosphorylase, phosphofructokinase, phosphoglycerate kinase, phosphoglycerate mutase, and lactate dehydrogenase) and one mitochondrial myopathy (cytochrome c oxidase deficiency) are reviewed to illustrate: 1) clinical heterogeneity, 2) biochemical heterogeneity, 3) evidence for tissue‐specific and developmentally controlled isozymes, and 4) molecular genetic studie

ISSN:0148-7299    

DOI:10.1002/ajmg.1320250406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractIn Duchenne dystrophy and in the genetic dystrophies of CHF‐147 hamsters and MDX mice, the fundamental deleterious consequence of dystrophic gene expression issegmental necrosis of skeletal muscle fibers. The nature of the gene defects and the pathogenesis of muscle fiber damage are not known. However, clinical and experimental evidence indicates that muscle fibers whose girth is below a certain level (estimated at approximately 20–25 μm in diameter in dystrophic hamsters and MDX mice) arenotsusceptible to necrosis. This apparent “immunity” has been observed in muscle fibers that are naturally of small girth (such as those in extraocular muscles), and in fibers that were prevented from growing normally by experimental procedures (hamsters and mice) or by pathological processes (Duchenne patients). The cellular or molecular basis by which small‐caliber muscle fibers are resistant to the necrotizing effect of the dystrophic gene expression remains unknown. In small‐caliber muscle fibers, the normal contraction‐related mechanical strains per unit surface area are relatively less than in larger fibers; this could explain their relative resistance to necrosis in so

ISSN:0148-7299    

DOI:10.1002/ajmg.1320250407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractPhosphorus magnetic resonance spectroscopy (P MRS) affords and innovative approach to the study of the oxidative enzyme content of normal and diseased muscles. Examples of the evaluation of the enzyme content of normal muscles by an exercise protoocol are provided. The protocol affords a hyperbolic work/cost profile, the Vmaxof which is calculated by the reciprocal plots giving the enzyme content and the “effective Michaelis constant” with an evaluation of the resting metabolism. This steady state protocol clearly illustrates enzyme adaptation, on the one hand, and tissue atrophy particularly in the case of tissue injury, Duchenne's dystrophy, and genetic deletion of specific enzymes, on the other hand. The method is rapid, safe, and affords a quantitative evaluation of the disease process and possibilities for following appropriate therapies. So far, approx 1000 examinations or normal and diseased human limbs have been carried out in our laboratory in over the past four ye

ISSN:0148-7299    

DOI:10.1002/ajmg.1320250408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0148-7299    

DOI:10.1002/ajmg.1320250409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

ISSN:0148-7299    

DOI:10.1002/ajmg.1320250410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractNew molecular developments in our understanding of Duchenne and Becker muscular dystrophies are affecting the practical approach to genetic counseling, carrier detection, and prenatal prediction for these disorders. A plan of an investigation combining DNA and conventional techniques is outlined that is suitable for centers not actively engaged in molecular genetics research, based on the detection of molecular deletions, the most efficient use of multiple DNA polymorphisms, and the integration of this data with creatine kinase and pedigree information. Such an approach now allows accurate carrier detection for most women at risk as well as an acceptable degree of accuracy in prenatal detection for a proportion of carrier women.

ISSN:0148-7299    

DOI:10.1002/ajmg.1320250411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY