Terminal complement complexes in acute poststreptococcal glomerulonephritis

Activation of the complement cascade occurs in most cases of acute poststreptococcal glomerulonephritis (APSGN) and results in the formation of the terminal complement complexes (TCC). To examine the possible role of TCC in the pathogenesis of glomerular injury in APSGN, we studied 30 patients with the clinical diagnosis of APSGN. All patients had an elevated plasma SC5b-9 concentration at the onset of clinical nephritis. Serial plasma concentrations showed an inverse linear relationship with time after onset of clinical disease (r=–0.59,P=0.0008), while plasma C3 concentrations showed a positive linear relationship (r=0.78,P=0.0001). Renal biopsies of 5 patients demonstrated co-localization of C5b-9, S-protein, and C3 deposition in a glomerular capillary loop and mesangial distribution. Urinary excretion of TCC in the acute phase of APSGN was not elevated and was not a useful marker of disease activity. These data suggest that in APSGN with terminal complement pathway activation the local generation of TCC may contribute to the pathogenesis of the disease.     

Inhibition of the amorphous calcium phosphate phase transformation reaction by polyphosphates and metal ions

Summary The induction time for amorphous calcium phosphate (ACP) phase transformation was monitored at pH 7.4 and T=25°C with [Ca²⁺]₀=[PO₄]₀=4.0×10⁻³ M, as a function of added crystal growth inhibitors Mg²⁺, Sr²⁺, Zn²⁺, pyrophosphate (PP), and tripolyphosphate (TPP). Metal ions increase the induction time for the initiation of the phase change reaction in the order Zn²⁺<Sr²⁺<Mg²⁺. For polyphosphates it was observed that both PP and TPP are potent inhibitors with TPP more effective than PP as expected. The combination of Mg²⁺ or Sr²⁺ and PP or TPP leads to a synergistic delay in the onset of the phase conversion. The greatest inhibition was observed for Mg²⁺ and TPP. Reaction solutions containing 2.0×10⁻⁴ M Mg²⁺ and 4.0×10⁻⁵ M TPP resulted in a 90% increase in the induction time over what would be anticipated from an additive effect from these species.     

Structural modification of receptor-binding technetium-99m complexes in order to improve brain uptake

Low brain uptake is a generally accepted problem in developing technetium-99m brain receptor imaging agents. For a class of potential 5-HT_2A receptorbinding agents we tried to improve the original low brain uptake of 0.4% injected dose (ID) in rats 5 min p.i. by modifying the lipophilic properties of the molecules. Because of the presence of a protonable nitrogen, which according to the pK _a value leads to ionization of the molecule at blood pH, the pK _a value was considered to be the parameter most suitable for adjustment of lipophilicity. Insertion of ether-oxygen in the molecule of five candidates lowers the apparent pK _a value from 10.0 to 8.3 and dramatically increases the brain uptake to 1.3% ID at 5 min. The direct relationship between brain uptake and apparent pK _a cannot be simply explained by the increase in the pK _a-governed proportion of the neutral species.     

EFFECT OF CIGARETTE SMOKING ON THE FREQUENCY OF VENTRICULAR PREMATURE COMPLEXES IN NORMAL SUBJECTS

1. Ambulatory ECG monitoring was undertaken in healthy cigarette smokers (33) and non-smokers (20) of similar age (21-66 years). 2. The frequency of ventricular premature complexes (VPC) was less in habitual smokers (P less than 0.05; Mann-Whitney rank test) and an average of more than 1 VPC per hour occurred in a higher proportion of non-smokers than smokers: eight of 20 (40%) vs two of 33 (6%) (P less than 0.01; Chi-square test).     

99mTc-labelling of leucocytes with 99mTc-DPO: a complex developed for myocardial imaging

The lipophilic ^99mTc-DPO complex, developed as a myocardial imaging radiopharmaceutical, was used to label leucocytes. After an incubation of 0.1 ml ^99mTc-DPO (8 g DMPE*2HCl) with mixed leucocytes in plasma, the labelling efficiency was over 70%. During incubation in 5 ml plasma, a loss of activity was found between 20% (1 h) and 35% (3 h) caused by elution. Disturbances of cell viability could not be found with the help of the chemiluminescence test. The in vivo recovery was determined in three dogs and was 45%–50% (0.5 h), 30%–36% (1 h), and 18%–24% (3 h). Autologous ^99mTc-DPO-leucocytes were used on seven patients with suspected osteomyelitis, there were four true negative and three true positive results. The target/nontarget ratio determined by ROI in the positive cases was 1.8 to 2.5 at 3 h after injection.     

Solid phase C1q microassay for the rapid detection of circulating immune complexes

A C1q solid phase microassay was designed for the rapid detection of circulating immune complexes. Its level of sensitivity is comparable to that of the Raji cell and greater than the C1q binding assay; furthermore, it is faster and low in cost. These conditions make it more practical and applicable in the clinical setting.     

Etiology of IgA nephropathy syndrome

Since Berger's original paper on mesangial IgA-IgG deposition with hematuria, there have been a number of clinical and pathological studies regarding IgA immune complexes, the mechanisms of glomerular IgA deposition leading to glomerular injury and animal models of IgA nephropathy. During the last quarter of this century, glomerular changes such as IgA nephropathy have also been observed in cases associated with other diseases, such as systemic lupus erythematosus, Schoenlein-Henoch purpura, liver cirrhosis and chronic inflammatory diseases of the lung. This evidence supports the idea of an IgA nephropathy syndrome. On the other hand, IgA is thought to be an important humoral factor at the mucosal immune system and appears to have an antibody function against various etiologic candidates of extrinsic or intrinsic substances at the mucosal and systemic immune system. Glomerular IgA deposition in IgA nephropathy syndrome is thought to result from elevated levels of circulating immune complexes or aggregated IgA due to an overproduction of polymeric IgA as antibodies in the serum and due to the clearance impairment of IgA immune complexes in the hepatic and splenic phagocytic system. The glomerular IgA subclass is not one-sided, but should be evaluated in comparison with the age of patients at renal biopsy; this indicates the approximate age of onset. Cirrhotic IgA glomerulonephritis is not related to Hepatitis B or C virus infection, but to the pathophysiologic condition of liver cirrhosis. Various etiologic candidates such as viral, microbial, dietary antigens or auto-antigens have been listed and experimental models of IgA nephropathy syndrome have provided some clues in understanding the etiology of primary IgA nephropathy. However much still remains to be clarified and some specific epitopes common among these etiologic candidates will have to be identified.     

Dissociation of hepatitis A virus antigen-anti-HAV antibody complexes by 2-mercaptoethanol and dithiothreitol

Intravenous inoculation of two marmosets and one chimpanzee with hepatitis A virus (HAV) resulted in the replication of virus in liver, excretion of HAV particles in stool, and the appearance of circulating antibodies specific for hepatitis A. The development of an early antibody response in the chimpanzee and in one of the two infected marmosets was shown to interfere with the serologic detection of HAV antigen (HAV Ag) in homogenates of acute phase liver tissue obtained from these animals. Treatment of HAV Ag-positive and IgM anti-HAV-positive liver homogenates with thiol reducing compounds was shown to release HAV Ag from in vitro formed immune complexes. The increased RIA response for HAV Ag in homogenates treated with 2-mercaptoethanol (2-ME) or dithiothreitol (DTT) was further shown not to be due to activation of HAV Ag itself or to a nonspecific effect on the RIA coating antibody, radiolabeled probe, or homogenized liver tissue. IgG and IgM double-antibody sandwich RIAs for HAV Ag were also compared for their ability to detect HAV Ag under reducing and nonreducing conditions. Application of the 2-ME or DTT treatment procedure to the serologic detection of other viral antigens or viruses whose presence in blood, stool, tissue macerate, or other milieu may be masked by specific antibody appears to be feasible.     

Characterization of Thymic Nurse-Cell Lymphocytes,Using an Improved Procedure for Nurse-Cell Isolation

Thymic nurse cells (TNC), multicellular complexes consisting of lymphoid cells enclosed within cortical epithelial cells, were isolated from mouse thymus by a modified procedure allowing immunofluorescent labeling and flow cytometric analysis of their lymphoid contents (TNC-L). Collagenase was the only protease used for tissue digestion, to ensure that surface antigen markers remained intact. Zonal unit-gravity elutriation was used to enrich the TNC on the basis of their high sedimentation rate, followed by immunomagnetic bead depletion to remove residual mononuclear cell contaminants and a density separation to remove debris. The TNC-L were then released from inside TNC by a short period of culture. The measured contamination of TNC-L with exogenous thymocytes was around 0.5%. Three-color immunofluorescent labeling revealed that TNC-L included, as well as a maiority of immature CD4⁺8⁺3^low thymocytes, about 12% of apparently mature CD4⁺8^-3^high and CD4^-8⁺3^high thymocytes. TNC are located in the cortex, where mature cells are rare; the occurrence of mature phenotype cells within these structures suggests that they represent a microenvironment for the selection and generation of mature T cells.