ISSN:1040-8711    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Recent advances in mitochondrial cytopathies are reviewed. Particular emphasis is given to diseases related to mitochondrial DNA mutations, a field now encompassing myopathic and encephalopathic syndromes, some more common degenerative disorders, and certain aspects of the aging process. Diseases caused by defective oxidative energy generation now have an important place in human pathology.

ISSN:1040-8711    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Advances in the understanding of the genetic basis for Duchenne muscular dystrophy over the past 4 years has led to the quick application of molecular diagnostics. More recently, attention has turned towards acquiring a better understanding of dystrophin biochemistry and the pathophysiologic consequences of dystrophin deficiency.

ISSN:1040-8711    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

A major recent advance in the field of muscle fiber types has been the discovery that myogenic factors regulate fiber phenotypic properties. Myogenic influences occur in limb and trunk (somitic) muscle, but are particularly strong in jaw-closing muscles and extraocular muscles that express some unique myofibrillar proteins. In somitic muscles, a variant of fast fiber has been discovered, making four types of fibers: I, IIA, IIX, and IIB. These fibers express different isoforms of myofibrillar and other proteins. The speed and power of the four types of fibers are distinct and are controlled principally by their myosin heavy chains, which modulate the two regulatory steps in the crossbridge cycle, one controlling the rate of development of force, the other controlling the maximal velocity of shortening. Fast fibers have a higher threshold for Ca2+-activated force and a steeper force-pCa relation than do slow fibers. This difference is largely attributable to the cooperativity in the attachment of crossbridges and to the difference in Ca2+binding capacity of their troponin C. Ca2+initiates force development in muscle by increasing the rate of attachment of crossbridges. The phosphorylation of myosin light chain enhances this action. This effect of phosphorylation underlies the phenomenon of posttetanic potentiation of the isometric twitch in fast fibers.

ISSN:1040-8711    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Myositis describes a heterogeneous group of disorders whose main pathologic feature is chronic inflammation of the affected muscles. The association of myositis with other autoimmune diseases, the response to corticosteroid and immunosuppressive therapy, the frequent occurrence of autoantibodies, and the presence of chronic inflammatory cells in the affected muscles of patients with myositis indicate that the myositis syndromes are autoimmune diseases. This review summarizes recent observations on the role of humoral and cellular mechanisms in myositis. During the past year, the most notable contributions included studies on the relationship among autoantibodies and various clinical and epidemiologic features of patients with myositis; further evidence for T-cell involvement in the pathogenesis of myositis; demonstration of amyloid proteins in muscle fibers of patients with inclusion body myositis; and a controlled trial of plasma exchange and leukapheresis in myositis.

ISSN:1040-8711    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Total creatine kinase measurement in serum has remained the best overall marker for detection and monitoring of skeletal muscle diseases, despite that different human tissues exhibit varying distributions of cytoplasmic and mitochondrial isoenzymes of creatine kinase. Acute myocardial infarction aside, increases in total serum creatine kinase, as reflected by the MM isoenzyme, are most commonly caused by injury or diseases to striated muscle. Enzyme markers of skeletal muscle injury that have been previously used (eg, aldolase, enolase, aspartate aminotransferase, and lactate dehydrogenase isoenzyme 5) are not as specific as creatine kinase and have limited clinical utility. However, new enzyme and protein markers are currently being investigated, eg, troponin and carbonic anhydrase III, which are more specific than creatine kinase toward particular tissues. Moreover, measurement of creatine kinase isoforms may provide information about whether muscle turnover is acute or chronic.

ISSN:1040-8711    

出版商:OVID    

年代:1992

数据来源: OVID

ISSN:1040-8711    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Raynaud's phenomenon occurs in about 5% of the adult population, and most individuals do not seek medical attention for the condition. In symptomatic patients with Raynaud's phenomenon, it is useful to categorize the condition as primary or secondary. In addition to providing a framework for epidemiologic and therapeutic protocols, such classification may reflect basic pathophysiologic differences. Occupation-related Raynaud's phenomenon has been recognized recently as a major cause of lost wages and productivity. Neurogenic and “local fault” hypotheses to explain primary Raynaud's phenomenon are still being studied. In secondary Raynaud's phenomenon, obliterative arteriopathy and the role of endothelial-derived products have been the focus of intense research interest. Under some circumstances, the combination of nailfold capillary microscopy and autoantibody analysis can identify patients with primary Raynaud's phenomenon that is likely to evolve into a secondary form of Raynaud's phenomenon. Although information from this type of analysis may be overinterpreted, the prognostic yield is highest for patients destined to develop systemic sclerosis-related disorders. Newer vasodilating agents and antithrombotic drugs may offer benefit for patients with both primary and secondary Raynaud's phenomenon.

ISSN:1040-8711    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Many patients presenting with symptoms suggestive of a connective tissue disease do not fulfill criteria for a specific connective tissue disease at initial presentation. Some of these patients with undifferentiated connective tissue disease eventually develop a specific connective tissue disease. Recently, a large cohort of 213 patients from different centers with undifferentiated connective tissue disease of early onset were enrolled in a prospective protocoled study. Baseline characteristics, including antinuclear antibody profiles, were reported. The aim of this study was to define predictors for the development of specific organ-system involvement and connective tissue diseases in early undifferentiated connective tissue disease. Many patients show overlapping features of two or more connective tissue diseases. The presence of autoantibodies to U1-ribonucleoproteins has been associated with a particular overlap syndrome, mixed connective tissue disease. Most anti-U1-ribonucleoprotein-positive patients with undifferentiated connective tissue disease at presentation appear to develop mixed connective tissue disease over the course of disease. Although levels of anti-U1 -ribonu-cleoprotein do not seem to be related to disease activity, this association suggests a pathogenetic relationship between anti-U1-ribonucleoprotein and mixed connective tissue disease. Genetic studies have shown that patients with antibodies against the 70-kD component of U1-ribonucleoprotein share a common epitope within the groove of their DR molecules at antigen-binding region, pointing to a particular antigen involved in the induction of these antibodies that may be relevant in the etiopathogenesis of associated disease.

ISSN:1040-8711    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

Now that renal disease is no longer the leading cause of death in patients with systemic sclerosis, attention has shifted to cardiopulmonary involvement. Several reports addressed the issue of whether the pulmonary vasculature in patients with systemic sclerosis is vasoactive or fixed, and one report addressed the use of high-resolution computed tomographic lung scan to diagnose active alveolitis. The issue of whether the clinical syndrome of thrombotic thrombocytopenic purpura in systemic sclerosis is part of, or is distinct from, scleroderma renal crisis has again been raised. Worsening of cutaneous and visceral systemic sclerosis following radiotherapy was noted in several reports.

ISSN:1040-8711    

出版商:OVID    

年代:1992

数据来源: OVID