Low copy numbers of complement C4 and C4A deficiency are risk factors for myositis, its subgroups and autoantibodies

BACKGROUND

Idiopathic inflammatory myopathies (IIM) are a group of autoimmune diseases characterised by myositis-related autoantibodies plus infiltration of leucocytes into muscles and/or the skin, leading to the destruction of blood vessels and muscle fibres, chronic weakness and fatigue. While complement-mediated destruction of capillary endothelia is implicated in paediatric and adult dermatomyositis, the complex diversity of complement C4 in IIM pathology was unknown.

METHODS

We elucidated the gene copy number (GCN) variations of total C4, C4A and C4B, long and short genes in 1644 Caucasian patients with IIM, plus 3526 matched healthy controls using real-time PCR or Southern blot analyses. Plasma complement levels were determined by single radial immunodiffusion.

RESULTS

The large study populations helped establish the distribution patterns of various C4 GCN groups. Low GCNs of C4T (C4T=2+3) and C4A deficiency (C4A=0+1) were strongly correlated with increased risk of IIM with OR equalled to 2.58 (2.28-2.91), p=5.0×10^-53 for C4T, and 2.82 (2.48-3.21), p=7.0×10^-57 for C4A deficiency. Contingency and regression analyses showed that among patients with C4A deficiency, the presence of HLA-DR3 became insignificant as a risk factor in IIM except for inclusion body myositis (IBM), by which 98.2% had HLA-DR3 with an OR of 11.02 (1.44-84.4). Intragroup analyses of patients with IIM for C4 protein levels and IIM-related autoantibodies showed that those with anti-Jo-1 or with anti-PM/Scl had significantly lower C4 plasma concentrations than those without these autoantibodies.

CONCLUSIONS

C4A deficiency is relevant in dermatomyositis, HLA-DRB1*03 is important in IBM and both C4A deficiency and HLA-DRB1*03 contribute interactively to risk of polymyositis.

Health teaching for people with disabilities

The authors inform nurses about their responsibility under the Americans with Disabilities Act to ensure equal access to health services and health education. This article is divided into two parts: (1) The Americans with Disabilities Act (ADA) is presented particularly in relation to health teaching. (2) Selected disabilities and helpful tips for positive interaction are discussed.

Biological and environmental risk for poor developmental outcome of young children

A cross-sectional retrospective study was conducted to develop and field test a state-wide screening method for identifying children at risk for developmental problems. Families of 2.5- to 3-year-old children were sampled from the Ohio birth certificate register. Standardized telephone interviews were conducted with 1,601 parents concerning home environment and demographic characteristics. Developmental delay, the outcome variable, was defined by low scores on an abbreviated Developmental Profile II, which was also administered over the telephone. Obstetric history and health status of the newborns was obtained from birth certificates. By means of logistic regression analysis, we found six independent variables representing environmental and biological determinants.

Risk Factors for Developmental Delay Among Infants and Toddlers

Definitions of risk, types of risk factors used in longitudinal studies of the development of infants and toddlers (0-3 years), and the predictive power of risk models in assessing developmental delays are reviewed. Biologic factors in combination with environmental risk factors give the best prediction of long-term outcome. When biological or environmental risk factors are examined independently, they are not powerful predictors. Recommendations are made for repeated screening for developmental risk factors during the first 3 years, and a model for provision of services is presented that assumes a differential risk algorithm.

Effect of three proteinaceous foreign materials on infected and subinfected wound models

A model was devised to determine the effects of several foreign bodies (microcrystalline collagen hemostat (MCCH), blood clot, catgut suture) on S. aureus wound contamination and wound infection. In a subinfected wound model, MCCH, when compared with the other foreign bodies, showed an increase in the number of wounds classified as "contaminated," but 84 percent of these wounds yielded bacterial counts below the level accepted for biologically significant wound infection (10 to the 5th power bacteria per gram tissue). The number of "infected" wounds was not significantly greater than the number found in the uninoculated control group. In the infected wound model, all groups of inoculated animals showed significant infections. The severity of the wound infection was unaffected by the presence of catgut suture, clotted blood, or MCCH. Higher levels were not seen for the MCCH animals than for the inoculated control animals. We did not see in these experimental wound studies with MCCH a significant aggravation of wound contamination or wound infection during the 48 hour period following inoculation with varying dose levels of S. aureus. Further studies would be necessary to determine the possible bacteriological response after 48 hours.