ISSN:1040-8711    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:1040-8711    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Metabolic myopathies are disorders of muscle energy production that result in skeletal muscle dysfunction. Cardiac and systemic metabolic dysfunction may coexist. Symptoms are often intermittent and provoked by exercise or changes in supply of lipid and carbohydrate fuels. Specific disorders of lipid and carbohydrate metabolism in muscle are reviewed. Evaluation often requires provocative exercise testing. These tests may include ischemic forearm exercise, aerobic cycle exercise, and31P magnetic resonance spectroscopy with exercise.

ISSN:1040-8711    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Major new advances in the genetic and biochemical characterization of mitochondrial myopathies are discussed, within a general presentation of this important new area of human pathology. Mitochondrial disorders can be due to mutations in either nuclear or mitochondrial genes involved in the synthesis of individual respiratory chain subunits or in their posttranslational control. Although no mutations of nuclear-encoded oxidative phosphorylation subunits have been reported so far in humans, numerous biochemically defined disorders are attributed to nuclear gene defects. In contrast, molecular lesions of mitochondrial DNA are recognized as an increasingly frequent cause of defective oxidative phosphorylation. Numerous new mutations recently have been identified, including both maternally inherited point mutations and sporadic large-scale rearrangements. In addition, the identification of new or overlap syndromes has substantially broadened the clinical spectrum of mitochondrial disorders. To gain insight into the pathogenesis of these disorders, the relationship between specific clinical presentations and the mitochondrial genotype has been intensively investigated. In most cases, the phenotypic expression of the mitochondrial DNA mutations depends on the interplay among the relative amount of mutated vs wild-type genomes,ie, the degree of mitochondrial heteroplasmy and its tissue and cell distribution, the reliance of the affected tissues on aerobic energy supply, the age and gender of the individual, and other still poorly understood factors including individual “nuclear genetic background” and environmental factors.

ISSN:1040-8711    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Polymyositis, dermatomyositis, and inclusion-body myositis are characterized by muscle cell infiltration and specific alterations on or within muscle fibers. Infiltrating immune cells (ie, T or B lymphocytes, macrophages, and natural killer cells) have distinctive distributions in these conditions: increased presence of CD8+/MHC I-restricted T lymphocytes at endomysial sites in polymyositis and more B than T lymphocytes perivascularly in muscles of dermatomyositis patients. Muscle-infiltrating T lymphocytes mainly express αβ T cell receptors (TCRs) in polymyositis; they also express TCRs characterized by oligoclonal Vβ repertoire, with a consensus motif indicating a conventional antigen as target of the immune attack. In inclusion-body myositis, TCRs with oligoclonal Vβ also are found, but no consensus motif has been identified, suggesting possible superantigen involvement in lymphocyte recruitment. Sequence analysis of TCRs in these lymphocytes has provided insight into the probable nature of the antigenic stimulus and into recruitment of these cells to the inflammation sites. T cell- or natural killer cell-mediated cytotoxic agents have been characterized by messenger RNA or protein expression in these inflammatory myopathies, and the roles of other cytokines in the inflammation processes have been determined.In vivoandin vitrostudies on muscle cells have assessed their functions as target cells or antigen-presenting cells. Combined molecular and cellular immunology studies on effector and target cells are expected to clarify the pathogenetic mechanisms underlying these inflammatory myopathies in the near future.

ISSN:1040-8711    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

The idiopathic inflammatory myopathies (IIMs) of childhood are a heterogenous group of rare diseases characterized by chronic skeletal muscle inflammation. Although juvenile dermatomyositis is the most common of these disorders, children may develop any of the other types of myositis that have been better studied in adults. These include not only the IIMs delineated by clinicopathologic features but also the serologic groups of myositis, recently defined by myositis-specific and myositis-associated autoantibodies. Differences in the frequencies of MM groups between children and adults suggest differences in exposures to myositis-inducing environmental agents or differences in the frequencies of susceptibility genes between these two populations. Further investigation of the heterogeneity of the childhood IIMs and of the newly described clinicopathologic and autoantibody groups should improve our understanding and treatment of these disorders.

ISSN:1040-8711    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Dermatologists have long recognized that patients occasionally exhibit the pathognomic skin changes of dermatomyositis without clinical evidence of myositis for much longer than is typical for the classic form of this disease. The termdermatomyositis siné myositishas been used to refer to this condition in the past, although there is virtually no written record of this entity in the English-language medical literature. During the past 5 years, the disease course in such patients has been formally described in several case reports and small retrospective series, often under the designationamyopathic dermatomyositis. In this review, we discuss clinical issues relating to this poorly understood illness, including the possibilities of the existence of subclinical myositis, risk of occlt malignancy, and risk of systemic disease manifestations normally associated with the classic form of dermatomyositis, such as interstitial lung disease. In addition, we address other issues of recent interest pertaining to the cutaneous manifestations of the inflammatory myopathies, such as unusual types of skin lesions, exacerbation of disease activity by ultraviolet light exposure, relative risk of intradermal bovine collagen injections, and management of corticosteroid-resistant skin lesions.

ISSN:1040-8711    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Dermatomyositis appears to be associated with a greater frequency of malignancy than expected in the general population. For polymyositis, there does not appear to be a greatly increased risk of malignancy. Ovarian cancer may be overrepresented in women with dermatomyositis and difficult to detect. A paraneoplastic course, in which the activity of the myositis parallels that of the malignancy, occurs in some patients but is unusual. Although the frequency of malignancy rises with increasing age, young patients may harbor malignancy. The search for malignancy should be directed by symptoms, findings on physical examination, or laboratory testing, and it should be age appropriate.

ISSN:1040-8711    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Among the main concerns regarding the current therapy for the inflammatory myopathies are a lack of adequate controlled trials, a lack of objective means to reliably measure muscle strength, lack of natural history data, consideration of polymyositis, dermatomyositis, and inclusion-body myositis as a homogeneous group of inflammatory myopathies, and reliance on nonspecific markers for determining prognosis and assessing response to therapies. Prednisone remains the drug of choice in treating these disorders, although a controlled trial has never been undertaken to study its efficacy. Among the steroid-sparing agents, azathioprine, methotrexate, cyclosporine, and chlorambucil are used with invariably low to moderate success. There are no results of controlled trials to indicate whether one of these drugs is superior to another. Intravenous immunoglobulin, which is very expensive, was shown in a controlled trial to be effective in steroid-resistant dermatomyositis not only in dramatically improving muscle strength and skin rash but also in resolving the underlying immunopathology. Controlled trials of intravenous immunoglobulin in patients with polymyositis and inclusion-body myositis are under way. Inclusion-body myositis has emerged as a common inflammatory myopathy that is predictably disabling and resistant to most therapies.

ISSN:1040-8711    

出版商:OVID    

年代:1994

数据来源: OVID

ISSN:1040-8711    

出版商:OVID    

年代:1994

数据来源: OVID