title: Nicotinamide adenine dinucleotide tetrazolium reductase identifies microvasculature activation in muscle from adult patients with dermatomyositis.
abstract: OBJECTIVE
  Previous work has suggested involvement of the muscle microvasculature in the pathogenesis of dermatomyositis (DM). Our study evaluates whether standard histochemical reactions can identify microvascular changes in muscle biopsies from patients with DM compared to myopathic and nonmyopathic controls.
  
  
  METHODS
  Muscle biopsies were obtained from 111 patients, including 45 patients with DM. Microvascular quantitation was performed on transversely oriented 1-μm toluidine blue-stained plastic sections. Histoenzymatic procedures included alkaline phosphatase (AP), nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR), succinate dehydrogenase (SDH), cytochrome C oxidase (COX), and myosin ATPase reactions.
  
  
  RESULTS
  Capillary density was significantly lower in DM muscle biopsies compared to biopsies from patients with noninflammatory myopathies (NIM; n = 26) and healthy control muscle (n = 27; mean ± SD: 252 ± 114 vs 402 ± 56 and 325 ± 109 capillaries/mm(2), respectively; p values < 0.05). In contrast, a marked increase in the number of capillaries staining with NADH-TR was noted in DM compared to other idiopathic inflammatory myopathies (IIM; n = 13), NIM, and controls (49.8 ± 50.7 vs 8.0 ± 7.1, 6.7 ± 7.2, and 3.6 ± 2.8 capillaries/mm(2); p < 0.05 compared to DM). DM capillaries also demonstrated mildly increased staining with AP compared to controls; however, no increased SDH or COX reactivity was observed.
  
  
  CONCLUSIONS
  DM muscle capillaries are highly reactive with NADH-TR compared to myopathic and nonmyopathic controls. The lack of staining of DM capillaries with mitochondrial SDH and COX reactions suggests that NADH-TR reactivity may be secondary to activation of the microvascular endoplasmic reticulum, rather than mitochondrial hyperplasia.
authors.affiliation: David Geffen School of Medicine at UCLA, 1000 Veteran Avenue, Room 32-59, Los Angeles, CA 90095-1670, USA. ccharles@mednet.ucla.edu
authors.forename: Christina
authors.initials: C
authors.lastname: Charles-Schoeman
authors.forename: M Anthony
authors.initials: MA
authors.lastname: Verity
mesh_terms: D000328:Adult; D001706:Biopsy; D003882:Dermatomyositis / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D055806:Microvessels / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D009243:NAD / Q000378:metabolism; D009246:NADH Tetrazolium Reductase / Q000378:metabolism*
chemical_list: D009243:NAD; D009246:NADH Tetrazolium Reductase