The role of fibronectin in the streptococcal adhesion process

The work shows that fibronectin obtained from human plasma is capable of binding with streptococci of different groups with almost equal effectiveness. Fibronectin bound to bacterial cells inhibits the adhesion of group A streptococci onto vaginal cells, but it produces no effect on the adhesion of group B streptococci. The binding constant of fibronectin 125I is equal to 10(6) -M-1, which indicates that the level of the specificity of interaction is not sufficiently high.     

Effects of death of a single neuron on the functional organization of the neuronal ensemble in the leech

The reaction of leech nervous system after elimination of individual mechanosensory neuron by intracellular Pronase injection were studied. In the motor neurons connected with killed cells at 14-90th days after the operation there were the changes of the resting membrane potential and amplitude of postsynaptic potentials developed by the stimulation of mechanosensory neuron. It is suggested that the leech nervous system serves as the dynamic formation depending on changes of neuronal ensemble structure.     

The possibility of using equine serum albumin in place of bovine serum albumin and ovalbumin in radioimmunological and immunoenzyme analyses and in virological practice

Horse serum albumin has been shown to meet the requirements to protein preparations for microanalysis and thus to be suitable for use in kits of reagents for the radioimmunological determination of insulin and myoglobin, for the determination of tick-borne encephalitis virus antigen by the method of the enzyme immunoassay and for the stabilization of proteins in the hemagglutination test and the hemagglutination inhibition test.     

Restoration of voltage-dependent antibrain antibody-inhibited calcium current by cyclic adenosine monophosphate

A dual-microelectrode voltage clamp technique was used for recording voltage-dependent calcium current (I_ca) in unidentified neurons isolated fromHelix pomatia. Neither intracellular injection of cyclic adenosine monophosphate (cAMP; 10 nA, 5 min) nor intracellular application of dibutyril-cAMP (dcAMP; 1 mM, 10–20 min) induced a change in normal I_ca or produce a reversible 10–20% reduction in amplitude. Adding S-100 protein fraction antibodies to the external medium led to the onset of calcium-dependent inactivation of I_ca, bringing amplitude of I_ca down to 15±12% of its initial level. Either cAMP or dcAMP then restored inhibited I_ca to 50±11% of its original level. It was found that the effects of cAMP on I_ca of intact neurons depend on level of cytoplasmic Ca²⁺.Institute for Brain Research, All-Union Center for Mental Health Research, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 21, No. 2, pp. 247–252, March–April, 1989.     

Quantitative structure activity relationship studies on 3-triazines using van der Waal volume and molecular connectivity index

QSAR studies have been performed on the homologues of 3-triazines, using molecular connectivity index and van der Waal volume as structural parameters. The regression analysis has shown good correlation between antitumour activity and the two structural parameters.     

The use of a mixture model in the analysis of count data

A mixture model is presented for the analysis of data on premature ventricular contractions. The analysis is shown to be straightforward and the conclusions relatively simple.     

Hemoglobin binding to deglycosylated haptoglobin

The carbohydrate portion of polymeric haptoglobin was gradually removed by exoglycosidases in order to investigate its role in complex formation between haptoglobin and hemoglobin. Total removal of sialic acid diminished the haptoglobin-hemoglobin complex formation 15%. Removal of about 25% of the galactose residues from asialohaptoglobin, i.e., about 40% of the total weight of the carbohydrate moiety, totally inhibited the ability of haptoglobin to form complex with hemoglobin and react with haptoglobin-specific antibodies. Liberation of further galactose residues resulted in slow precipitation of the protein. Removal of a similar part of the carbohydrate moiety from haptoglobin-hemoglobin complex did not liberate hemoglobin from it, and the complex reacted with haptoglobin antibodies. The combined data indicate that the carbohydrate portion is essential for the functionally active form of polymeric haptoglobin to complex with hemoglobin, but it hardly has any direct role in the binding event, and other factors are responsible for the stability of the complex.     

Computer analysis of regulatory signals in complete bacterial genomes. Translation initiation of ribosomal protein operons]

Signals of translation initiation of operons of Haemophilus influenzae ribosomal proteins were predicted. This process is regulated by the formation of secondary RNA structures to which one of the proteins encoded in a particular operon binds. In some cases, these structures imitate the region of protein binding to rRNA. Predictions are made by comparing with homologous operons of Escherichia coli and analogous regions of rRNA and by estimating the energy of secondary structure formation. It is shown that this regulatory mechanism occurs: in operons L11, S10, S15, spc, and alpha of H.influenzae and, probably, in operon S15 of Helicobacter pylori, Bacillus subtilis, and Mycoplasma genitalium.