Search results for "c1q"

Molecular basis of a new type of C1q-deficiency associated with a non-functional low molecular weight (LMW) C1q: parallels and differences to other k…

1998

Analysis of an abnormal C1q molecule of individuals of a Moroccan family by ultracentrifugation in sucrose gradients revealed a low molecular weight C1q (LMW-C1q). We investigated the molecular basis of this defect by sequencing all six exons of the three C1q genes. One point mutation in the codon for Gly at position 15 (GGT) of the B chain was found resulting in an amino acid substitution to Asp (GAT). The exchange not only leads to an interruption of the collagen-like motif Gly-X-Y, but also introduces one negatively charged residue per B chain which results in two additional charges per structural subunit (A-B, C-C, A-B). The mutation which has been identified by DNA-sequencing in the C1…

Are laboratory tests useful for monitoring the activity of lupus nephritis? A 6-year prospective study in a cohort of 228 patients with lupus nephrit…

2008

Objectives:To evaluate the role of immunological tests for monitoring lupus nephritis (LN) activity.Methods:C3, C4, anti-dsDNA and anti-C1q antibodies were prospectively performed over 6 years in 228 patients with LN.Results:In membranous LN only anti-C1q antibodies differentiated proteinuric flares from quiescent disease (p = 0.02). However, in this group 46% of flares occurred with a normal value of anti-C1q antibodies versus 20% in proliferative LN (p = 0.02). In patients with antiphospholipid antibodies (APL), 33% of flares occurred with normal levels of anti-C1q antibodies versus 14.5% in patients that were APL-negative (p = 0.02). In proliferative LN, anti-C1q antibodies showed a slig…

Complete functional C1q deficiency associated with systemic lupus erythematosus (SLE).

1993

SUMMARY A complete functional deficiency of Clq is described in a patient suffering from SLE. From reduced plasma C1 activity of the parents a hereditary trait was assumed. The defective C1q molecule was haemolytically inactive, did not bind to immune complexes, and was not recognized by the monocyte C1q receptor. C1 activity in the patient's serum could be restored by the addition of purified C1q. Analysis by gelfiltration and ultracentrifugation experiments revealed an immunoreactive molecule of about 150 kD mol. wt, corresponding to one structural subunit of the C1q macromolccule, containing two A chain-B chain dimers and a C-C chain dimer. Applying Southern blot analysis with cDNA clone…

Anti-C1q Autoantibodies in Lupus Nephritis: Prevalence and Clinical Significance

2005

Recently, anti-C1q autoantibodies have been proposed as a useful marker in systemic lupus erythematosus (SLE) since their occurrence correlates with renal involvement and, possibly, with nephritic activity. We aimed to evaluate the prevalence of anti-C1q antibodies in patients with SLE, with and without renal involvement, and to correlate these markers' presence and levels with the activity of the disease and nephropathy. We studied 61 patients with SLE, 40 of whom had biopsy-proven lupus nephritis; 35 patients with other connective tissue diseases; and 54 healthy controls. In addition, 18 lupus nephritis patients were followed up during the disease time course. Anti-C1q antibodies were mea…

C1q induces in vivo angiogenesis and promotes wound healing

2011

Pyridinedicarboxylates, the first mechanism-derived inhibitors for prolyl 4-hydroxylase, selectively suppress cellular hydroxyprolyl biosynthesis. De…

1987

Two pyridinedicarboxylates, predicted [Hanauske-Abel (1983) M.D.-Ph.D. Thesis, Philipps Universität Marburg] and later found to be potent reversible inhibitors of purified prolyl 4-hydroxylase [Majaama, Hanauske-Abel, Günzler & Kivirikko (1984) Eur. J. Biochem. 138, 239-245] were investigated with respect to their effect on hydroxyprolyl biosynthesis in the fibroblast/collagen and the macrophage/Clq systems, and the effect was compared with that of the iron chelator 2,2′-dipyridyl, the compound usually employed to inhibit cellular hydroxyprolyl formation. Only the enzyme-mechanism-derived pyridinedicarboxylates were highly selective inhibitors, and only they lacked overt cytotoxicity. M…

Subcellular targeting of multiligand-binding protein gC1qR.

1999

Abstract gC1q receptor, a protein originally described as the cell surface receptor for the globular heads of complement factor C1q, has been found to bind human H-kininogen with high affinity and specificity. Therefore, gC1qR has been considered candidate kininogen docking site on the surfaces of platelets, neutrophils and endothelial cells. Recent work demonstrating that gC1qR is an intracellular protein that is tightly associated with mitochondria rather than targeted to the cell surface has challenged this view. To further probe cellular trafficking routes of gC1qR, we overexpressed human gC1qR in a mammalian cell and monitored cell surface exposure of recombinant gC1qR by virtue of its…

Effect of EDTA and citrate on the functional activity of the first component of complement, C1, and the C1q subcomponent.

1985

The first component of complement, C1, is a calcium-dependent complex of the three distinct subcomponents, C1q, C1r, and C1s. Earlier observations revealed that treatment of C1 with EDTA led to a loss of hemolytic C1 activity even after recalcification. Therefore, it was of interest to study whether EDTA has an additional effect on C1 and its subcomponents, beside its chelating capacity. The chelating effect of EDTA was compared to that of citrate. It was found that treatment of C1 or C1 with EDTA followed by addition of Ca++ led to a loss of hemolytic activity up to 90%, depending on EDTA concentration. Even pretreatment of EDTA with varying amounts of Ca++ did not prevent the inactivation…

Binding and activation of human and mouse complement by Cryptosporidium parvum (Apicomplexa) and susceptibility of C1q- and MBL-deficient mice to inf…

2008

Cryptosporidium parvum is a protozoan parasite (Apicomplexa) that causes gastrointestinal disease in animals and humans. Whereas immunocompetent hosts can limit the infection within 1 or 2 weeks, immunocompromised individuals develop a chronic, life-threatening disease. The importance of the adaptive cellular immune response, with CD4+ T-lymphocytes being the major players, has been clearly demonstrated. Several non-adaptive immune mechanisms have been suggested to contribute to the host defence, such as interferon-gamma (IFN-gamma) from NK cells, certain chemokines, beta-defensins and pro-inflammatory cytokines, but the influence of the complement systems has been less well studied. We ana…

The Role of the Classical Pathway for the Bactericidal Effect of Normal Sera Against Gram-Negative Bacteria

1985

Many gram-negative bacteria are killed after treatment with normal serum. This phenomenon was already described in 1889 by Buchner. The serum-bactericidal effect is abolished when serum has been incubated for 30 min at 56° C. Gram-positive bacteria are less sensitive than gram-negative bacteria to direct killing, although gram-positive cocci are opsonized by the action of serum mediated by antibodies and complement (Inoue et al. 1968; Johnston et al. 1969). Normal sera exhibit bactericidal and bacteriolytic properties against some gramnegative strains; whereas, other gram-negative strains are serum resistant. It has been shown that serum from C4-deficient guinea pigs is able to kill some gr…