Search

In vitro induced oxidative damage to normal human RBCs has previously been shown to result in increased membrane rigidity as a consequence of the generation of a protein complex between hemoglobin and spectrin. In order to determine if in vivo generated hemoglobin-spectrin complexes may play a role in increased membrane rigidity of certain pathologic red cells, we measured both these parameters in membranes prepared from hereditary xerocytosis (Hx), sickle cell disease (Sc), and red cells from thalassemia minor (beta thal). Membranes were prepared from density-fractionated red cells, and membrane deformability was measured using an ektacytometer. Hemoglobin-spectrin complex was determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel analysis, as well as by Western blot analysis using a monoclonal antibody against the beta- subunit of hemoglobin. For these three types of pathologic red cells, progressive cellular dehydration was associated with increased membrane rigidity and increased content of hemoglobin-spectrin complex. Moreover, the increase in membrane rigidity appeared to be directly related to the quantity of hemoglobin-spectrin complex associated with the membrane. Our findings imply that hemoglobin-spectrin complex is generated in vivo, and this in turn results in increased membrane rigidity of certain pathologic red cells. The data further suggest that oxidative crosslinking may play an important role in the pathophysiology of certain red cell disorders.

An internal molecular deletion occurring in a human lambda type immunoglobulin light (L)-chain (Sm lambda) has been defined by sequence analysis. The Sm protein was isolated from the urine of a patient with a plasma cell dyscrasia involving the synthesis of an IgG molecule with both deleted gamma and lambda subunits. The Sm lambda polypeptide chain has an approximate molecular weight of 15,000 and contains 135 amino-acid residues. The constant (C) region is fully intact, comprising 105 residues, whereas the variable region (V) has only 30 residues. The V-region segment represents residues 1 through 30 of normal lambda chains and possesses considerable homology (87%) to lambda chains of subgroup II. Since lambdaII proteins normally contain 216 amino-acid residues, the defect represents an intramolecular deletion of 81 residues, which is entirely confined to the carboxyterminal three-quarters segment of the V-region, with a resumption of normal synthesis at a glutaminyl residue at position 110, the initiation point of the C-region. Carbohydrate is attached to an Asx residue at position 25, in the first hypervariable region, associated with the sequence triplet Asx-Ser-Ser, which is postulated to be a common recognition site for glycosylation of immunoglobulins. The carbohydrate moiety is a complex oligosaccharide with a branched chain structure containing sialic acid, fucose, mannose, N-acetylglucosamine, and galactose. These structural studies and other findings suggest that restricted areas in the DNA of immunoglobulin genes, such as the hinge regions of heavy (H) and light (L) chains and the hypervariable regions, are particularly susceptible to breakage and reunion. We postulate that the genetic defect of protein Sm could have originated from a somatic mutational event in the plasmacyte precursor during or after the integration of the V and C genes. These studies provide additional support for the hypothesis and two distinct structural genes encode a single immunoglobulin polypeptide chain.

We developed a monoclonal antibody against HPLC purified rat lens γL crystallins. This antibody was specific to both the polypeptides (19,000 and 21,000 daltons) which constituted the HPLC γ1 peak. Least reactivity was shown against γH (24,000b daltons). This antibody was used as a probe to detect the presence of and quantitate γ1 crystallins in lens soluble, insoluble and urea-insoluble fractions during diabetes. Utilizing a direct binding immunoassay (ELISA) we calculated the absolute quantities of γl crystallins present in these fractions. Our results show, in normal animals there was a minimal change in total quantities of γL crystallins in soluble fraction from 1 month to 5 months of age, but a slow accumulation of these crystallins in insoluble and urea-insoluble fractions was seen during the same period. Diabetes resulted in a depletion of γL crystallins from the soluble fraction, both in terms of relative proportion and absolute quantities. In insoluble and urea-insoluble fractions the relative proportions of these crystallins were increased dramatically up until 60 days followed by a decrease during 90-120 days of diabetes, whereas, the absolute quantities remained more or less steady after reaching the maximum on 60 days.Although the relative proportions of γL crystallins in the insoluble fraction seem to be less when compared to urea-insoluble fraction, the total quantity of these crystallins was much higher due to abundance of this fraction. These results demonstrate that the early diabetic cataract events (up to 60 days) were associated with selective insolubilization and association with membranes of γLcrystallins while the later stages of cataract seem to involve other crystallins.

Escherichia coli strain chi 1776 carrying recombinant DNA plasmids containing cDNA copies of human beta or gamma globin mRNAs has been shown by radioimmunoassay to synthesize polypeptides antigenically related to the beta and gamma chains of human hemoglobin. The gamma and beta polypeptides have been enriched from lysates on immunoabsorbent columns containing hemoglobin antibodies and shown to specifically inhibit the antigen-antibody binding between 125I-labeled hemoglobin and the homologous antibody but not other hemoglobin-antihemoglobin reactions. Clone JW151, which is known to contain a complete copy of the coding portion of the gamma globin mRNA, has been shown to produce a protein that reacts specifically with antibody to the chain of fetal hemoglobin, hemoglobin Kenya, and hemoglobin Bart's.

Presents several letters to the editor. Effect of free trade on democratic peace; Analysis of patent medicine; Discussion about ancient and modern History.