Blockade of clearance of immune complexes by an anti-F(cγ) receptor monoclonal antibody

Clearance of immune complexes by the mononuclear phagocyte system is important for maintaining normal host defenses against bacterial and viral assault (1), but also contributes to the pathogenesis of a variety of immune- mediated diseases . For example, removal from the circulation of IgG-coated erythrocytes and platelets by the MPS is the sine qua non of immune-mediated cytopenias (2, 3). On the other hand, abnormally decreased removal by the MPS of smaller, soluble immune complexes may play a role in the pathogenesis of immune complex-mediated tissue damage found in such autoimmune diseases as SLE (4). Although the physicochemical nature and the size of immune complexes can influence rates of clearance and sites of deposition (reviewed in 5), interactions between immune complexes and the MPS in vivo are poorly understood. The inability to directly measure binding or internalization of immune complexes by cells in the liver and spleen has made the analysis of the molecular basis of immune complex clearance very difficult . Receptors for the Fc portion of IgG (FcγR) and for complement (CR) undoubtedly play a role in the removal of immune complexes, but the relative importance of these receptors is not known.     

SIDS, illness, and acute medical care. New Zealand Cot Death Study Group

One component of the Back to Sleep campaign to reduce the risk of sudden infant death syndrome (SIDS) is the recommendation that parents seek medical attention if their infant is unwell. The aim of this study was to investigate of SIDS could in part be explained by sick infants not getting appropriate medical care. Data on symptoms of illness and on acute medical contacts made for infants dying from SIDS (n = 390) within two weeks of their death were compared with those from a randomly selected group of control infants (n = 1592). SIDS cases had more severe illness than controls (odds ratio (OR) = 3.43; 95% confidence interval (CI) = 1.69 to 5.38), and were more likely to have seen a general practitioner (OR = 1.37; 95% CI = 1.09 to 1.73) or attended hospital (OR = 3.43, 95% CI = 1.09 to 1.73). Only 1.3% of all SIDS cases had symptoms suggesting severe illness and had not seen a general practitioner. A lack of medical contacts in the two weeks before death does not contribute to the risk of SIDS.     

Small unilateral jaw gap variations: equilibrium changes, co-contractions and joint forces

Summary  After complex prosthetic reconstructions, small differences in vertical distances between the left and right side of the jaw may occur during jaw closing, nevertheless providing bilateral tooth contacts in intercuspation by small deformations of the mandible. Their effects on the co-contraction of the masticatory muscles, the temporomandibular joint reaction forces, and the point of application of the resultant bite force vector in the maxillary occlusion plane – the so-called reduction point – have not been investigated, thus far simultaneously in one sample. The main goal of this study was to investigate variations of these measures in an experimental intercuspation simulated by one anterior and two posterior force transmission points.     

Extremely high avidity association of Fe(III) with the sickle red cell membrane

Red blood cells (RBCs) from patients with sickle cell anemia and thalassemia carry abnormal accumulations of molecular Fe(III) at the cytosol/membrane interface. The avidity of the red cell membrane for this iron has not been defined. Using open ghost membranes prepared from sickle RBC, we examined the ability of membrane-associated Fe(III) to resist removal by 15 chelators representing a 40-log range of affinities for Fe(III). Efficacy of chelators was compared with literature values for their idealized affinity for iron as represented by the cummulative stability constant (beta n), their effective stability constant reflecting affinity under biologic conditions (Keff), and an indicator of their ability to chelate Fe(III) in the presence of an insoluble phase of iron (Ksol). Deferoxamine, a very high affinity chelator having log beta n = 30.6, was found to be the lowest affinity chelator able to remove RBC membrane Fe(III). Regardless of chelator beta n, only those agents able to preserve log Keff > or = 12 were able to do so, indicating that the membrane's effective avidity for Fe(III) is on the order of 10(12). Additional confirmation that membrane avidity for Fe(III) is extremely high is found in the observation that only chelators having log Ksol > 0 were effective. Potential physiologic iron chelators in cytoplasm of pathologic red cells are unable to prevent or reverse iron accumulation on the membrane because they do not have sufficiently high affinity for iron. These data argue that RBC membrane Fe(III) is truly pathologic.