Formation of classical C3 convertase during the alternative pathway of human complement activation

The fluid phase C3 convertase of the alternative pathway of human complement activation has been constructed from the isolated C3 component and from purified factors B and D. The enzyme was able to activate the isolated components C4 and C2 in the presence of C4 but had no effect on C2 in the absence of C4. The C4 and C2 activation was monitored by the loss of their hemolytic activity during the incubation with the alternative fluid phase C3 convertase. The activation of C4 and C2 components by the membrane-bound alternative C3 convertase formed on red cells (EC3bBb) was followed by the formation of C3 convertase of the classic pathway--EC4b2a. This resulted in the enhancement of hemolysis.     

Lipoxygenase inhibitors suppress intracellular calcium rise induced by ionomycin in rat thymocytes

The lipoxygenase (LO) inhibitors nordihydroguaiaretic acid (NDGA) and 15S-hydroxy-5,8,11,13-(Z,Z,Z,E)-eicosatetraenoic acid (15-HETE) have been found to suppress the rise in free cytoplasmic Ca2+ concentration [( Ca2+]i) induced by the Ca2+ ionophores ionomycin and A23187 in rat thymocytes. Bromophenacyl bromide (BPB), a phospholipase A2 (PLA2) inhibitor, produced a much weaker inhibitory effect, and indomethacin, a cyclo-oxygenase inhibitor, practically did not influence the [Ca2+]i response to ionomycin. These findings implicate the involvement of LO product(s) in the [Ca2+]i rise triggered by the Ca2+ ionophores. The contribution of the NDGA-sensitive component to the ionomycin-induced [Ca2+]i rise was significant in the ionomycin concentration range of 0.1 nM to 0.1 microM whereas at higher doses of the ionophore it gradually diminished. By contrast, the [Ca2+]i rise induced by exogenous arachidonic acid (AA) or melittin, a PLA2 activator, was not suppressed but potentiated by NDGA. Ionomycin and exogenous AA also elicited opposite changes in thymocyte cytoplasmic pH (pHi): the former elevated the pHi while the latter induced a pronounced acidification of the cytoplasm. This difference in the pHi responses may account for the different sensitivity of ionomycin- and AA-elicited [Ca2+]i signal to LO inhibitors.     

Diversity and Prevalence of Hereditary Diseases among Nogais of the Karachay-Cherkess Republic

The diversity and prevalence of hereditary diseases (HDs) among Nogais of the Karachay-Cherkess Republic (KChR) are described. The size of the surveyed KChR population was 387231 individuals, including 3.81% Nogais (14741 individuals). We revealed 36 nosological forms of HDs (110 patients from 81 families): 22 with autosomal dominant (AD) inheritance, 10 with autosomal recessive (AR) inheritance, and 4 with X-linked inheritance. The prevalence of HDs in Nogais was 1: 134. The features of HD diversity in Nogais were determined in comparison with the previously surveyed populations of Russia. The accumulation of Ehlers–Danlos syndrome (1: 388), AD amelogenesis imperfecta (1: 3685), AD ichthyosis (1: 4914), AR nonsyndromic mental retardation (1: 1340), AR Gilbert syndrome (1: 4914), and X-linked inherited deficit of glucose-6-dehydrogenase (1: 1774 males) was established. The analysis of heterozygous carriage of mutations “major” for Russia in the genes of the four following AR diseases in 118 unrelated clinically healthy Nogais (236 analyzed chromosomes) was performed: cystic fibrosis (13 mutations in the CFTR gene: CFTRdele2,3 (21 kb), F508del, I507del, 1677delTA, 2184insA, 2143delT, 2183AA>G, 2184delA, 394delTT, 3821delT, L138ins, E92K, W1282X); phenylketonuria (six frequent mutations in the PAH gene: R261X, R408W, R413P, F331S, P211T, P211L); nonsyndromic sensorineural hearing loss (35delG mutation in the GJB2 gene); and Gilbert syndrome (an increase in the number of TA repeats in the UGT1A1 gene). Allelic specificity for all studied genes in the Nogai people was revealed.     

Interaction of Cholera Toxin B Subunit with Rat Intestinal Epithelial Cells

We prepared ¹²⁵I-labeled cholera toxin B subunit (¹²⁵I-labeled CT-B, specific activity 98 Ci/mmol) and found that its binding to rat IEC-6 intestinal epithelial cells was high-affinity (K_d 1.9 nM). The binding of labeled protein was completely inhibited by unlabeled thymosin-α₁ (TM-α₁), interferon-α₂ (IFN-α₂), and synthetic peptide LKEKK, which corresponds to residues 16–20 in TM-α₁ and 131–135 in IFN-α₂ (K_i 1.2, 0.9, and 1.6 nM, respectively), but was not inhibited by synthetic peptide KKEKL with inverted amino acid sequence (K_i > 10 μM). Thus, TM-α₁, IFN-α₂, and the LKEKK peptide bind with high affinity and specificity to CT-B receptor on rIEC-6 cells. It was found that CT-B and the LKEKK peptide at concentrations of 10–1000 nM increased nitric oxide production and soluble guanylate cyclase activity in the cells in a dose-dependent manner.     

Soy and Rapeseed Protein Hydrolysis by the Enzyme Preparation Protosubtilin

A comparative study of soybean and rapeseed protein hydrolysis by protosubtilin, an original Russian enzyme preparation widely used in animal feed production, has been performed. SDS-PAG electrophoresis, HPLC, and mass spectrometry have been employed to analyze the obtained products. The soybean protein isolate used for hydrolysate production was obtained from a commercial supplier, and rapeseed proteins were prepared from the meal by alkali extraction. Low molecular weight impurities were removed by ultrafiltration. The degree of protein hydrolysis has been shown to depend on the substrate-to-enzyme preparation ratio, hydrolysis time, and protein concentration. Rapeseed protein hydrolysis by protosubtilin at an enzyme/protein ratio of 1: 20 and hydrolysis time of 20 h resulted in complete cleavage of the proteins present in the raw material and the accumulation of oligopeptides (molecular weight less than 14 kDa) and free amino acids, which accounted for 53 and 8% of the initial protein weight, respectively. In contrast to rapeseed proteins, soybean proteins showed considerable gelling at the initial stages of hydrolysis, and the formation of insoluble hydrolysis-resistant fragments was observed. The soluble part of the hydrolysate contained short oligopeptides and free amino acids, which accounted for 13% of the initial protein weight only.     

Bioconversion of Phenolic Monomers of Lignin and Lignin-Containing Substrates by the Basidiomycete <Emphasis Type="Italic">Lentinus tigrinus</Emphasis>

The bioconversion of phenolic monomers of lignin (veratrol, vanillin, and vanillyl alcohol), hydrolyzed lignin, and sodium lignosulfonate (a product of the chemical modification of native lignin) by the basidiomycete Lentinus tigrinus was studied. It was found that the growth of the fungi on lignin monomer compounds is suppressed. A noticeable growth of the fungal biomass was observed only on the technical substrate sodium lignosulfonate. A comprehensive physicochemical study of the products of microbial transformation of sodium lignosulfonate was performed. It was established that the main direction of lignin bioconversion is oxidative condensation to form humic substances. In this case, depolymerization of the phenolic skeleton of lignin to monomeric phenol derivatives did not occur. The aromatic carbon atoms of the phenolic skeleton, unlike the carbon atoms of polysaccharides, were not involved in the fungal biomass growth. The observed growth of the fungus on the technical substrate sodium lignosulfonate can be explained by the presence of admixtures of oligomeric polysaccharides hemicellulose and cellulose, which can be used by the fungus as a carbon source.     

Repercussions of the COVID-19 pandemic on athletes: a cross-sectional study

The COVID-19 pandemic has presented significant challenges and implications for the sports community. Thus, this study aimed to describe the prevalence of COVID-19 in Brazilian athletes and identify the epidemiological, clinical, athletic, life and health factors associated with the disease in these individuals. A cross-sectional study was performed involving 414 athletes from 22 different sports using an online questionnaire from August to November 2020. The association between the athletes’ characteristics and COVID-19 was evaluated using a logistic regression model. The prevalence of COVID-19 was 8.5%, although only 40% of athletes reported having been tested. Being under 27 years of age (3-fold), having children (~5-fold), having a teammate test positive for COVID-19 (2.5-fold), and smoking (14-fold) were associated with a possible higher risk of disease. Almost 20% of athletes self-reported musculoskeletal injuries during the period of the pandemic that was studied. Athletes with a university education (P = 0.02), a profession other than sports (P < 0.001), those from a low-income family (P = 0.01), and public health system users (P = 0.04) were significantly less frequently tested for COVID-19, whereas international competitors, athletes who received a wage, and athletes who had a teammate who tested positive for COVID-19 were 2-, 3-, and 15-fold more likely to be tested for COVID-19, respectively. Approximately 26% of the athletes who tested negative or were untested reported more than three characteristic COVID-19 symptoms, and 11% of athletes who tested positive for COVID-19 were asymptomatic. The identification of modifiable (have children, smoking, and teammates positively tested) and non-modifiable (age under 27 years) factors related to COVID-19 in athletes can contribute to implementing surveillance programmes to decrease the incidence of COVID-19 in athletes and its negative impacts in sports.     

Conformational behavior of giant DNA through binding with Ag+ and metallization

The conformational behavior of a long single-chain double-stranded DNA in solutions of free silver ions and silver nanoparticles generated via the reduction of AgNO3 by NaBH4 was monitored by fluorescence and electron microscopies and UV spectroscopy. The interaction of monovalent silver ions with DNA induces shrinking of a DNA-coiled polymer chain as a result of a decrease in the DNA persistence length through the complexation of Ag+ with DNA bases. In contrast, the reduction of silver ions by NaBH4 in DNA solutions triggers DNA compaction: a DNA transition from elongated coil state into a compact state. This transition is continuous, unlike the all-or-none discrete DNA compaction that is commonly seen with multications. It is suggested that the collapse of DNA is accompanied by growth aggregation of silver nanoparticles generated on the DNA template.