Various parameters of humoral and cellular immunity in children with iron deficiency

Serum IgA, IgM and IgG as well as percentage of lymphocytes T and B in peripheral blood were determined in 50 children aged between 6 months and 3 years with iron deficiency anaemia. A significant decrease in lymphocyte T number in these children was found in comparison with control group of healthy children. Lymphocyte T count positively correlated with serum iron concentration. Moreover, a decrease in serum IgA and IgG was found in children with iron deficit.     

Production of enterotoxin A by supposedly nonenterotoxigenic Staphylococcus aureus strains

The production of staphylococcal enterotoxins A (SEA) and B (SEB) was studied by inoculating six well-defined staphylococcal collection strains into cow's, goat's, or sheep's milk (individually or as a 50% mixture of cow's + goat's or cow's + sheep's), into brain heart infusion, and into a medium generally used to enhance the synthesis of enterotoxins (3+3 medium). Four of the strains used are considered to be SEB producers, another is considered an SEA producer, and the remaining strain is nonenterotoxigenic but produces large quantities of staphylococcal protein A. Staphylococcal protein A masked the results in most cases. Only one strain secreted exclusively SEB, while the other three SEB producers synthesized SEA in different amounts. We conclude that enterotoxin production depends on the natural substrate and may differ from the results obtained when the strain is grown on cellophane over agar to determine its toxigenicity.     

Posttranslational regulation of keratins: degradation of mouse and human keratins 18 and 8.

Human keratin 18 (K18) and keratin 8 (K8) and their mouse homologs, Endo B and Endo A, respectively, are expressed in adult mice primarily in a variety of simple epithelial cell types in which they are normally found in equal amounts within the intermediate filament cytoskeleton. Expression of K18 alone in mouse L cells or NIH 3T3 fibroblasts from either the gene or a cDNA expression vector results in K18 protein which is degraded relatively rapidly without the formation of filaments. A K8 cDNA containing all coding sequences was isolated and expressed in mouse fibroblasts either singly or in combination with K18. Immunoprecipitation of stably transfected L cells revealed that when K8 was expressed alone, it was degraded in a fashion similar to that seen previously for K18. However, expression of K8 in fibroblasts that also expressed K18 resulted in stabilization of both K18 and K8. Immunofluorescent staining revealed typical keratin filament organization in such cells. Thus, expression of a type I and a type II keratin was found to be both necessary and sufficient for formation of keratin filaments within fibroblasts. To determine whether a similar proteolytic system responsible for the degradation of K18 in fibroblasts also exists in simple epithelial cells which normally express a type I and a type II keratin, a mutant, truncated K18 protein missing the carboxy-terminal tail domain and a conserved region of the central, alpha-helical rod domain was expressed in mouse parietal endodermal cells. This resulted in destabilization of endogenous Endo A and Endo B and inhibition of the formation of typical keratin filament structures. Therefore, cells that normally express keratins contain a proteolytic system similar to that found in experimentally manipulated fibroblasts which degrades keratin proteins not found in their normal polymerized state.     

Incorporation of ionic channels from yeast plasma membranes into black lipid membranes.

Recently, patch-clamping of yeast protoplasts has revealed the presence of plasma membrane K+ channels (Gustin, M. C., B. Martinac, Y. Saimi, M. R. Culberston, and C. Kung. 1986. Science (Wash. DC). 233:1195-1197). In this work we show that fusion of purified plasma membranes into planar bilayers allows the study of the yeast channels. The main cationic conductances detected were of 64 and 116 pS, however, larger and smaller conductances have been observed. The two main conductances were sensitive to the K+ channels blockers tetraethylammonium (TEA+) and Ba2+. Bionic experiments indicated that both conductances were K+ selective.     

The use of functional analysis of the ribosome as a tool to determine archaebacterial phylogeny

Forty different antibiotics with diverse kingdom and functional specificities were used to measure the functional characteristics of the archaebacterial translation apparatus. The resulting inhibitory curves, which are characteristic of the cell-free system analyzed, were transformed into quantitative values that were used to cluster the different archaebacteria analyzed. This cluster resembles the phylogenetic tree generated by 16S rRNA sequence comparisons. These results strongly suggest that functional analysis of an appropriate evolutionary clock, such as the ribosome, is of intrinsic phylogenetic value. More importantly, they indicate that the study of the nexus between genotypic and phenotypic (functional) information may shed considerable light on the evolution of the protein synthetic machinery.     

Utilization of alanine for glucose formation in isolated rabbit kidney-cortex tubules

In kidney cortex tubules isolated from fed rabbits L-alanine is not utilized as glucose precursor, when added as a sole substrate. However, this amino acid decreases gluconeogenesis from low (up to 1 mM) 2-oxoglutarate concentrations and stimulates this process at higher (2.5-10 mM) ketoacid contents in the suspension medium. Aminooxyacetate, an inhibitor of aminotransferases, abolishes both inhibitory and stimulatory effects of L-alanine on glucose formation. The addition of 2-oxoglutarate increases the incorporation of L-[U-14C]alanine to glucose from 8- to 123-fold, depending upon the ketoacid and alanine concentrations used. In contrast, nonlabelled L-alanine decreases the incorporation of low [U-14C)2-oxoglutarate concentrations into glucose, while it does not affect contribution of 5 mM ketoacid to gluconeogenesis. The data indicate that (i) in the presence of 2-oxoglutarate L-alanine is utilized as glucose precursor in rabbit renal tubules and (ii) this amino acid may decrease the contribution of low extracellular concentrations of the ketoacid to gluconeogenesis.     

Production of enterotoxin A by supposedly nonenterotoxigenic Staphylococcus aureus strains.

The production of staphylococcal enterotoxins A (SEA) and B (SEB) was studied by inoculating six well-defined staphylococcal collection strains into cow's, goat's, or sheep's milk (individually or as a 50% mixture of cow's + goat's or cow's + sheep's), into brain heart infusion, and into a medium generally used to enhance the synthesis of enterotoxins (3+3 medium). Four of the strains used are considered to be SEB producers, another is considered an SEA producer, and the remaining strain is nonenterotoxigenic but produces large quantities of staphylococcal protein A. Staphylococcal protein A masked the results in most cases. Only one strain secreted exclusively SEB, while the other three SEB producers synthesized SEA in different amounts. We conclude that enterotoxin production depends on the natural substrate and may differ from the results obtained when the strain is grown on cellophane over agar to determine its toxigenicity.     

In vitro transport of ornithine carbamoyltransferase precursor into rat liver mitochondria using a more homologous medium

The precursor of ornithine carbamoyltransferase can be transported in vitro into rat liver mitochondria using the postmitochondrial supernatant from rat liver, a more homologous medium than the commonly used rabbit reticulocyte lysate. The transport of the precursor in the case of reticulocyte lysate requires a standard translation mixture. In the presence of the postmitochondrial supernatant the same is true. However, when the components of the translation mixture were added individually to the postmitochondrial supernatant, it was found that spermidine or spermine, at physiological concentrations, sufficed for the transport of the precursor of ornithine carbamoyltransferase. The activity of the postmitochondrial supernatant was inactivated by trypsin and slightly decreased by RNase treatment; it was not lost by dialysis or by heating at 100 degrees C.     

Investigation of dye/protein interaction and its application to enzyme purification

In this review the results of the interaction of the active dyes used in the USSR textile industry with microbial enzymes and blood serum proteins are discussed. The complexity of dye/protein interaction and the dependence of this interaction on different factors is demonstrated. Some practical aspects of the use of dye containing sorbents are presented and discussed. Their suitability for RNA ligase and DNA ligase, acetate kinase, alcohol dehydrogenase, lactate dehydrogenase and glucose-6-phosphate dehydrogenase purification and blood serum protein fractionation is demonstrated.