Anoxia-induced changes in purine nucleoside metabolism of in vitro aged human fibroblasts.

Inosine deriving from the metabolism of adenosine or inosine monophosphate (IMP) in the fibroblast provides the substrate for xanthine oxidase and is, therefore, an important source of toxic oxygen free radicals. With well-oxygenated medium, adenosine release appears to be greater for aged than young fibroblasts. In that the adenosine release by young cells is enhanced by reduced oxygenation, the effect anoxic stress on the release of the purine nucleosides adenosine and inosine by low-passage (PDL 23-26; young) vs.

[Pathophysiology and clinical aspects of myxedema].

The pathophysiology and clinical presentation of myxedema is reviewed in this article. Myxedema represents the leading symptom in hypothyroidism but also occurs in a localized form in autoimmune hyperthyroidism. Even in subclinical cases of thyroid diseases may myxedema represent a valuable symptom in establishing the correct diagnosis.

Adsorption and helical coiling of amphipathic peptides on lipid vesicles leads to negligible protection from cathepsin B or cathepsin D.

The processing of antigenic peptides for presentation by MHC molecules to T cells, may depend upon the function of a second, consensus sequence in or near the T cell-presented epitope. One such processing-regulating sequence appears to be composed of amino acids Leu, Ile, Val, Phe, and Met recurring in a fashion to form a longitudinal, hydrophobic strip when the excised peptide is coiled as an alpha-helix. Such a hydrophobic strip-of-helix may: (a) scavenge peptides from lumens onto lipid membranes of digestion vesicles, (b) stabilize peptides there as protease-resistant helices, (c) specify recognition by the antigenic peptide-binding sites of chaperonin proteins, transmembranal transporters, or MHC molecules.

Identification of p70 and p80 associations with class II MHC molecules and Ii.

Two proteins, p70 and p80, were found in chemically crosslinked complexes with class II MHC molecules and Ii after 3-12 hr labelings with [35S]methionine. Two-dimensional, nonreduced/reduced SDS gel electrophoresis of immunoprecipitated complexes revealed 1) endogenous disulfide linkages between Ii-Ii and Ii-p70 and 2) chemically crosslinked, nearest neighbors of alpha-beta, alpha-Ii, Ii-p70, and alpha-p80. Although such nearest neighbors within multimeric complexes were identified as dimers in nonreduced/reduced 2D gels, stoichiometries could not be determined in the high molecular weight complex(es), which included alpha, beta, Ii, p70, and p80, and were not separated in the first dimension.

Synthetic peptides to identify antigenic determinants on Epstein-Barr virus gp350/220.

We synthesized three peptides, MA1 - Thr19-Val28(+Tyr) -, MA2 - Ser807-Ala816-, and MA3-Ser718-Glu729(+Tyr) from the sequence of Epstein-Barr virus gp350/220 and immunized rabbits with these peptides. Rabbit antisera to the peptides had antipeptide radioimmunoassay titers of 1:400 for anti-MA1, 1:200 for anti-MA2, and 1:1600 for anti-MA3. The anti-MA1 serum recognized gp350/220 in Western blotting to SDS-electrophoresed proteins from 12-O-tetradecanoylphorbol-13-acetate- and n-butyrate-treated B95-8 cells, but anti-MA2 and MA3 sera did not.

Testing for cell surface forms of class II major histocompatibility complex antigens and Ii by radioiodination, biotinylation, and membrane immunofluorescence.

Antibodies to either Ii or class II major histocompatibility complex (MHC) antigens did not recognize cell surface forms of Ii in immunoprecipitates of cells that had been radioiodinated by the lactoperoxidase method, whereas they bound [35S]methionine metabolically labeled molecules. N-hydroxysuccinimidobiotin (NHS-B) and biotin hydrazide (B-H) were used to react more generally with cell surface proteins via amino groups and nitrene coupling, respectively. Each of these latter compounds labeled alpha and beta chains of class II MHC antigens as seen in Western-blotted, electrophoresed immunoprecipitates probed with 125I-labeled streptavidin but not Ii or its associated forms.

[Hepatitis non-A, non-B-associated substance in stool from patients with posttransfusion and sporadic hepatitis].

A hepatitis non-A,non-B-associated substance (HNANB-AS) excreted in feces has been detected by means of a sandwich radioimmunoassay using reconvalescent serum and IgG from patients with posttransfusion HNANB. 4380 stool filtrates from 1599 patients were screened with this assay. In patients with posttransfusion or sporadic acute and chronic HNANB the substance was detected with a mean frequency of 34%, in acute posttransfusion HNANB, where samples were screened at the beginning of the clinical symptoms, 71.

Hyperexpressed hairy leukemic cell Ii might bind to the antigen-presenting site of class II MHC molecules.

The p35 protein which is hyperexpressed on hairy leukemic cells was determined to be Ii, the electrophoretically invariant glycoprotein that is associated with class II major histocompatibility complex (Ia) antigens from the time of their synthesis. The principal function of class II MHC antigens is to present to T cell receptors those digested foreign antigenic peptides that probably fold as amphipathic alpha-helices and adsorb to a hydrophobic surface (desetope) on Ia. By a novel strip-of-helix hydrophobicity algorithm we found that the sequence Leu-142 to His-170 in Ii formed a five-cycle, amphipathic, alpha-helix, the highest scoring one among a series of proteins commonly used as experimental antigens.

Functional association of class II antigens with cell surface binding of Epstein-Barr virus.

A functional role of class II antigen in the binding of Epstein-Barr virus (EBV) was deduced from the study of membrane proteins on Jijoye, an EBV receptor (EBVR)-positive B cell line, and its mutant, EBVR-negative daughter cell line, P3HR-1. From gel electrophoresis of radiolabeled microsomal membrane proteins and immunoprecipitates, we identified class II antigen on Jijoye but not on P3HR-1 cells and the presence of Ii on both cell lines. The role of these molecules in EBVR function was tested by antibody blocking of virus adsorption.

Inhibition of Epstein-Barr virus (EBV) release from the P3HR-1 Burkitt's lymphoma cell line by a monoclonal antibody against a 200,000 dalton EBV membrane antigen.

In raising murine hybridoma antibodies against Epstein-Barr virus (EBV)-induced membrane antigens (MA), we found one antibody that blocked the release of infectious EBV from cultured P3HR-1 cells. This monoclonal antibody (mAb) recognized a 200 kD, phosphonoacetic acid-sensitive (late) MA, and did not directly neutralize virus without complement. When this mAb was added to 33 degrees C-cultured, spontaneously EBV-producing P3HR-1 cells, the intracellular expression of viral capsid antigen and infectious virus was not inhibited, but the appearance of infectious virus in the culture medium was significantly reduced.

Analysis of transformation with Epstein-Barr virus and phenotypic characteristics of lymphoblastoid cell lines established from patients with hairy cell leukemia.

In order to assess the role of Epstein-Barr virus (EBV) in patients with hairy cell leukemia (HCL), we have sought to characterize 1) the ability of EBV to infect and transform hairy leukemic cells in vitro and 2) the phenotypes of cell lines putatively derived from those leukemic cells. Analysis of EBV-induced transformation and the kinetics of Epstein-Barr nuclear antigen (EBNA) induction in leukemic preparations indicated that most leukemic cells were not susceptible to EBV infection but that at least a small subpopulation of leukemic cells could be infected with EBV. Lymphoblastoid cells lines were established after exposure of peripheral blood or splenic cells from HCL patients to B95-8 or QIMR-WIL EBV.

Restrictions upon Epstein-Barr virus infection of the leukemic cell are demonstrated in patients with hairy cell leukemia.

We tested the hypothesis that Epstein-Barr virus (EBV) might actually infect leukemic hairy cells in vivo by examining those cells for the EBV-receptor, EBV nuclear antigen (EBNA) and membrane antigen (MA), for spontaneous transformation and rescue of infectious virus and for presence of EBV genome. EBV-receptors were found on subpopulations of leukemic cells from each of 7 patients with hairy cell leukemia (HCL) tested. MA was present on low numbers (1-5 per cent) of fresh leukemic cells of 7 patients and in some instances occurred with a greater frequency after 3 to 5 days in culture, with or without 12-O-tetradecanoylphorbol-13-acetate.

In vitro characterization of response to stimulus (wounding) with regard to ageing in human skin fibroblasts.

Confluent cultured normal human skin fibroblasts from neonatal, adult and aged donors have been stimulated to respond to wounding of the cell sheet. The latent period prior to initial migration of cells from the leading edge of the monolayer is correlated with in vitro population doubling level and in vivo donor age. Time-lapse photography of areas along the edge of the cell sheet reveals a specific pattern of migration by which the cells reestablish a confluent monolayer.