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Biomedical subjects

R J Pickering

Publications and source records attributed to R J Pickering.

At least 55 records · Page 3Linked to original sources
PubMed1970

Deficiency of C1r in human serum. Effects on the structure and function of macromolecular C1.

THE EXPERIMENTS PRESENTED HERE UTILIZE A HUMAN SERUM MARKEDLY DEFICIENT IN HEMOLYTIC COMPLEMENT ACTIVITY TO SHOW THAT: (a) The hemolytic deficiency is the result of a selective deficiency in hemolytic C1. (b) The relative absence of hemolytic C1 is due to a profound deficit in C1r function associated with less than normal C1s protein and hemolytic function and normal C1q protein concentration and function. This deficit in C1r in the face of normal C1q suggests that different cell types are responsible for the synthesis of each of these components. (c) Whatever the basis for the deficiency of C1r function, this defect results in an inadequate association of the remaining C1 subcomponents, C1q and C1s, even in the presence of calcium ions, thus suggesting that C1r has an important role in the assembly and/or maintenance of macromolecular C1.

Adolescent↗
PubMed1970

Interactions of the complement system with endotoxic lipopolysaccharides in immunoglobulin-deficient sera.

Bacterial lipopolysaccharides (LPS) derived from a variety of organisms effectively induced C consumption in humans, bovines, and porcines with developmental agammaglobulinemia; birds with experimental agammaglobulinemia; and humans with agammaglobulinemia syndromes. This interaction proceeded even in precolostral piglet sera which contained less than 2.5 x 10(-6) mg/ml gamma globulin, and led to generation of neutrophil chemotactic factor and anaphylatoxin in these sera. Hence, the LPS-C interaction can proceed in sera markedly deficient in immunoglobulin. The question of whether immunoglobulins can be bypassed in the LPS-C interaction, or whether they are regularly utilized in a way so efficient that their participation is masked, was considered.

Agammaglobulinemia↗
PubMed1970

Complement in endotoxin shock: effect of complement depletion on the early hypotensive phase.

The complement (C) inhibition caused by bacterial endotoxin is well known, but the relationship of this reaction to endotoxin shock is unclear. Anesthetized dogs were therefore given Escherichia coli endotoxin intravenously with or without prior C depletion by a purified cobra venom factor (CVF). Mean aortic blood pressures (MAP) and C levels were measured. Intravenous CVF usually caused an early transient drop of MAP and a profound, long-lasting drop in C. Bacterial lipopolysaccharide (LPS) alone always caused a sudden (within 2 min) drop in MAP which was followed by partial recovery and then more long-lasting depression. Moderate drops in C usually occurred. In animals pretreated with CVF so that C levels were markedly depressed (<25% of control), LPS did not elicit the immediate MAP drops; however, a later (after 5 to 20 min) MAP drop always occurred. CVF pretreatment did not modify LPS-induced mortality. CVF effects were not caused by LPS contamination. These data show that the early hemodynamic responses of the dog to LPS may be mediated through the complement system.

Journal Article↗
PubMed1969

Passive hemolysis by serum and cobra venom factor: a new mechanism inducing membrane damage by complement.

The studies presented here indicate that activation of the complement (C') system by a foreign protein will cause membrane injury and passive lysis of unsensitized erythrocytes present at the time of the reaction. These observations suggest that in addition to the classical antibody-C'-induced cytolysis, there are alternative pathways or mechanisms for activation and participation of the terminal C' components in the production of cell membrane injury. We have shown that a substance derived from cobra venom and eluted from a single protein band on polyacrylamide can promote lysis of unsensitized autologous or heterologous erythrocytes in the presence of fresh guinea pig serum and that this lysis-inducing activity and C'-inhibiting activity appear to reside in the same fractions. The lytic activity is prevented by several agents known to impair classical C'3 activity, but is unaffected by certain procedures which interfere with the function of C' components C'1 and C'2, a suggestion that this reaction involves chiefly C'3-C'9. Further, the cobra venom (CV) factor depletes C' activity in cobra serum, and the CV factor (with its 5S serum cofactor) converts purified C'3 to its inactive form,(1) indicating that the reaction of this complex with the complement system occurs without participation of antibody. Therefore, since the lysis-inducing and C'-inhibiting activity of the CV factor appear to result from similar interactions with the complement system, these observations suggest that cell membrane damage and cell lysis can be accomplished through activation of the complement system by a mechanism involving little or no participation of classical antibody or C' components C'1, 4, or 2.

Animals↗