Simulation of thymus hypo- and hyperplasia by thymalin in guinea pigs

Potentialities of the modulation of thymus function with thymalin and the hormonal-immunological status in simulated hypo- and hyperplasia of the thymus. The advisability of the use of the drug was shown.     

Functional state of the hypothalamo-hypophyseal-thyroid system in euthyroid hyperplasia of the thyroid gland

Function of the hypothalamo-hypophyseal-thyroid system was investigated in 51 patients with euthyroid hyperplasia. Basal and TRH-stimulated levels of TSH and STH were investigated. Hyperergic ejection of STH and two pathological types of STH reaction (suggesting dysfunction of the hypothalamohypophyseal-thyroid system in euthyroid hyperplasia) were revealed. A group of patients with a low level of STH in response to TRH-stimulation demonstrated more pronounced changes of the hypothalamo-hypophyseal-thyroid system, characterized by a rise of a TSH level in response to stimulation up to 27.59 +/- 3.7 microU and a slightly reduced level of thyroid hormones. Changes in the level of STH indicated certain interest of growth hormone in the genesis of thyroid hyperplasia and could also serve an additional sign in the evaluation of a severity of disorders of the hypothalamo-hypophyseal-thyroid system.     

Differences in the amino acid sequences of the P66 surface-exposed loop regions in various isolates of Borrelia afzelii

The intraspecific differences between the amino acid sequences of the P66 protein surface-exposed loop region (89 amino acids) in 45 isolates of 7 different allelic variants of B. afzelii were studied. It was established that this group includes 6 phenotypically different variants, two of which have different amino acid substitutions in the surface-exposed loop region, as well as different mutations in the putative monoclonal antibody H1337 binding site. The level of similarity between these phenotypic variants was 96.66–98.88%. It has been shown that, in a natural locus, up to three different amino acid variants of the studied P66 protein surface-exposed loop region can circulate simultaneously.     

Chemical sensing in mammalian host–bacterial commensal associations

The mammalian gastrointestinal (GI) tract is colonized by a complex consortium of bacterial species. Bacteria engage in chemical signaling to coordinate population-wide behavior. However, it is unclear if chemical sensing plays a role in establishing mammalian host–bacterial commensal relationships. Enterohemorrhagic Escherichia coli (EHEC) is a deadly human pathogen but is a member of the GI flora in cattle, its main reservoir. EHEC harbors SdiA, a regulator that senses acyl-homoserine lactones (AHLs) produced by other bacteria. Here, we show that SdiA is necessary for EHEC colonization of cattle and that AHLs are prominent within the bovine rumen but absent in other areas of the GI tract. We also assessed the rumen metagenome of heifers, and we show that it is dominated by Clostridia and/or Bacilli but also harbors Bacteroidetes. Of note, some members of the Bacteroidetes phyla have been previously reported to produce AHLs. SdiA-AHL chemical signaling aids EHEC in gauging these GI environments, and promotes adaptation to a commensal lifestyle. We show that chemical sensing in the mammalian GI tract determines the niche specificity for colonization by a commensal bacterium of its natural animal reservoir. Chemical sensing may be a general mechanism used by commensal bacteria to sense and adapt to their mammalian hosts. Additionally, because EHEC is largely prevalent in cattle herds, interference with SdiA-mediated cattle colonization is an exciting alternative to diminish contamination of meat products and cross-contamination of produce crops because of cattle shedding of this human pathogen.     

Nonstructural glycosylated polyproteins coded for by the gag gene of retrovirus type D expressed on the plasma membrane

Studies of virus-specific proteins of type D retroviruses by radioimmunoprecipitation (RIP) using various radioactive precursors demonstrated in HEp-2 cells producing these retroviruses the presence of two glycosylated gag-coded polyproteins with molecular weights of 78 K and 90 K. The same polyproteins were found by lactoperoxidase iodination and RIP on the plasma membrane of the cells. Comparative studies of these glycoproteins by the limited proteolysis method showed the sites for trypsin action in them to be located in similar places of protein bases which indicated their structural relationship. It is suggested that glycosylated gag-coded polyproteins of retroviruses (including type D retroviruses) play the role of receptors for certain mitogens the seizure of which stimulates cell proliferation.