Erythrocytic diagnostic agents for determining antibodies to Proteus O antigens

Highly sensitive and specific erythrocyte diagnostic agents (ED) for the determination of antibodies to Proteus O-antigens have been obtained by the sensitization of formolated sheep red blood cells (SPBC) with activated lipopolysaccharides (LPS) without the use of mediators. The tannin treatment of formolated SRBC and/or the increase of temperature from 45 degrees C to 100 degrees C in the process of the preparation of ED have been found to produce no increase in effectiveness. Antibody ED permitting the detection of Proteus O- and H-antigens has been obtained by the sensitization of formolated chick red blood cells with immunoglobulin preparations to Proteus hydroxylamine antigens, carried out with the use of amidol. The experiments have shown the possibility of using this antibody ED for the determination of O-antibodies in the antigen neutralization test with nonactivated LPS used as an agglutinating agent. The passive hemagglutination test with antibody ED has proved to be a more sensitive method for the detection of O-antibodies than the antigen neutralization test with antigenic ED. The determination of Proteus etiology in the passive hemagglutination test with the use of antigenic ED has been shown to be highly effective in the examination of patients with chronic osteomyelitis at the stage of exacerbation.     

Substrate specificity of mammalian folylpoly-gamma-glutamate synthetase for 5,8-dideazafolates and 5,8-dideaza analogues of aminopterin

The substrate specificity of pig liver folylpolyglutamate synthetase (tetrahydrofolate:L-glutamate gamma-ligase (ADP-forming), EC 6.3.2.17) for classical 5,8-dideaza analogues of folic acid, isofolic acid aminopterin and isoaminopterin has been investigated. 5,8-Dideazafolate and 5,8-dideazaaminopterin are very effective substrates with activities approaching those of the best reduced folate substrates. The analogous isofolate analogues are less effective substrates, but still better than folic acid. The 5-chloro substituent is the only modification that consistently increases the on rate, with 5-chloro-5,8-dideazaaminopterin being the most effective substrate found, thus far, for the enzyme. Methylation at positions 9 or 10 generally decreases binding, while 5-methylation increases the binding of 4-oxoquinazolines, but decreases the binding of their 4-amino counterparts. The presence of a formyl group at N9 or N10 has the opposite effect, decreasing the binding of 4-oxo analogues while increasing the rate for 4-amino derivatives. Increases in on rate with methyl, formyl or 4-amino substitutions are only significant when the parent compound is a poor substrate, suggesting that these groups do not interact directly with the enzyme but cause conformational changes in the structure of the substrate that influence binding to the enzyme.     

Thyroxine and palatal development in rat embryos

The placental transport and palatal localization of l-thyroxine-¹²⁵I was studied in Sprague-Dawley rat embryos ages 13 and 14 days in vivo and 14–16 days in vitro. Amniotic fluid, placenta and (by late day 14) embryonic/palatal and liver areas were assayed by scintillation counting and protein analysis. Radioactivity was found in amniotic fluid as early as 13 days in vivo. A small but consistent amount of radioactivity above control levels was found in the embryonic palatal and liver areas. Autoradiographs of thin-layer chromatographs showed that most of the radioactive label was at the thyroxine area in both 13- and 14-day in vivo and 15-day in vitro amniotic fluid pools. A small amount of radioactivity was present in the diiodothyronine area in both. Some activity was also present in the triiodothyronine area in the 13- and 14-day samples. No labelled inorganic iodide was detectable. The thyroid gland in rat does not begin to function until 17 days in utero. Accordingly, the labelled thyroxine was exogenous. The presence of labelling in the embryonic palate suggests a possible involvement of this hormone in palatal embryogenesis.     

Glycosyl conjugates of biotinylated diaminopyridine applied for study of carbohydrate-to-carbohydrate interaction

Previous studies by us and others established that cell-cell adhesion is mediated by specific carbohydrate-to-carbohydrate interaction (CCI). Those previous studies were based on various biochemical and biophysical approaches, including the use of labeled glycosyl epitopes with fluorescent tag. However, these methods ideally require that the glycosyl epitope must be fixed to a solid phase molecule, preferably with multivalency. The purpose of the present study is to establish a CCI process using specific glycosyl residues conjugated to biotinylated diaminopyridine (BAP), and to observe: (i) clear occurrence of homotypic CCI between “Os Fr.B” having 5–6 GlcNAc termini, vs. absence of such homotypic CCI between “Os Fr.1” having 2 GlcNAc termini; (ii) occurrence of heterotypic CCI between GM3 ganglioside and Os Fr.B, vs. absence of such heterotypic CCI between GM3 and Os Fr.1. Interaction between Os Fr.B-BAP conjugate and Os Fr.B-ceramide mimetic (Os Fr.B-mCer) was demonstrated based on two experiments: (i) dose-dependent binding of Os Fr.B-BAP conjugate to polystyrene plates coated with Os Fr.B-mCer was observed in the presence of bivalent cation, a prerequisite for all CCI processes, and such binding was abolished by EDTA; (ii) binding between equal nanomolar Os Fr.B-BAP and Os Fr.B-mCer was inhibited by mM concentration Os Fr.B without conjugate, in dose-dependent manner. Thus, cell adhesion processes based on homotypic CCI between N-linked glycans having multiple GlcNAc termini, and heterotypic CCI between GM3 and such glycans, were clearly observed using BAP conjugates of glycosyl epitopes.     

Absence of functional and structural homology of natural and recombinant human leukocyte interferon (IFN-α) with human α-ACTH and β-endorphin

A comparison of the amino acid sequence of one human recombinant IFN-α (IFLrA) with either human β-endorphin or ACTH reveals only a minimal and insignificant degree of homology. Also, synthetic ACTH, β-endorphin and β-endorphin-(1–15) have no antiviral protective effects on human fibroblasts and cannot inhibit the neutralization of the antiviral effects of natural IFN-α by an antiserum directed against the interferon. Anti ACTH and Anti β-endorphin do not neutralize the antiviral effects of IFLrA, and radioimmunoassays of partially purified natural IFN-α and pure IFLrA do not reveal any evidence of α-MSH or β-endorphin-like material in the interferons. These results demonstrate an absence of functional and structural homology of natural and recombinant IFN-α with ACTH and β-endorphin.     

Class II genes of the human major histocompatibility complex. The DO beta gene is a divergent member of the class II beta gene family

A novel class II beta chain gene is described. This gene, tentatively called DO beta, displays considerably less polymorphism than beta genes of the DP, DQ, and DR loci. The nucleotide sequence of the DO beta gene is strikingly similar to that of the previously identified murine A beta 2 gene. The DO beta gene displays the same exon/intron organization as other beta genes although the fifth exon and the translated portion of the sixth exon are longer than in other genes. A striking feature of the amino acid sequence deduced from the DO beta gene sequence is the pronounced hydrophobicity of the NH2-terminal region. This feature distinguishes the putative DO beta chain from other class II beta chains and raises the possibility that DO beta chains may interact with an alpha chain that is structurally different from those of the DP, DQ, and DR loci. It further suggests that the putative DO molecule may have a function different from those of other class II antigens.