Dynamic Interactions of Post Cleaved NS2B Cofactor and NS3 Protease Identified by Integrative Structural Approaches

Diseases caused by flaviviruses such as dengue virus (DENV) and West Nile Virus (WNV), are a serious threat to public health. The flavivirus single-stranded RNA genome is translated into a polyprotein which is cleaved into three structural proteins and seven non-structural proteins by the viral and cellular proteases. Non-structural (NS) protein 3 is a multifunctional protein that has N-terminal protease and C-terminal helicase domains. The NS3 protease requires co-factor NS2B for enzymatic activity and folding. Due to its essential role in viral replication, NS2B-NS3 protease is an attractive target for antiviral drugs. Despite the availability of crystal structures, dynamic interactions of the N- and C-termini of NS2B co-factor have been elusive due to their flexible fold. In this study, we employ integrative structural approaches combined with biochemical assays to elucidate the dynamic interactions of the flexible DENV4 NS2B and NS3 N- and C-termini. We captured the crystal structure of self-cleaved DENV4 NS2B₄₇NS3 protease in post cleavage state. The intermediate conformation adopted in the reported structure can be targeted by allosteric inhibitors. Comparison of our new findings from DENV4 against previously studied ZIKV NS2B-NS3 proteins reveals differences in NS2B-NS3 function between the two viruses. No inhibition of protease activity was observed for unlinked DENV NS2B-NS3 in presence of the cleavage site while ZIKV NS2B-NS3 cleavage inhibits protease activity. Another difference is that binding of the NS2B C-terminus to DENV4 eNS2B₄₇NS3Pro active site is mediated via interactions with P4-P6 residues while for ZIKV, the binding of NS2B C-terminus to active site is mediated by P1-P3 residues. The mapping of NS2B N- and C-termini with NS3 indicates that these intermolecular interactions occur mainly on the beta-barrel 2 of the NS3 protease domain. Our integrative approach enables a comprehensive understanding of the folding and dynamic interactions of DENV NS3 protease and its cofactor NS2B.     

Loneliness before and during the COVID-19 pandemic—are unpartnered and childless older adults at higher risk?

COVID-19 mitigation efforts had the potential to exacerbate loneliness among older adults, particularly for the unpartnered or childless, yet specific studies on loneliness among these groups during the COVID-19 pandemic are lacking. Using data from the Survey of Health, Ageing and Retirement in Europe (SHARE) collected before (October 2019–March 2020) and during the pandemic (June–August 2020), we examine two loneliness outcomes: (1) “have you felt lonely recently?” (both datasets) and (2) “have you felt lonelier than before the pandemic?” (2020), and examine differences by partnership and parenthood status. Before COVID-19, those who lacked one tie but had the other (unpartnered parents or partnered childless) were at highest loneliness risk. During COVID-19, unpartnered and childless—especially unpartnered—remain at higher risk for loneliness, entering loneliness, and not “exiting” loneliness. We discuss these findings in light of family norms and needs in pandemic and non-pandemic times and provide recommendations for future research.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10433-022-00718-x.     

Anti-osteopenic effect of alpha-ketoglutarate sodium salt in ovariectomized rats

The purpose of the study was to determine the effect of alpha-ketoglutarate sodium salt (AKG) treatment on the mineralization of the tibia in female rats during the development of osteopenia (Experiment-1) and in the condition of established osteopenia (Experiment-2). Thirty-two female rats were ovariectomized (OVX) to induce osteopenia and osteoporosis and another 32 female rats were sham-operated (SHO) and then randomly divided between the two experiments. In Experiment-1, the treatment with AKG started after a 7-day period of convalescence, whereas in Experiment-2 the rats were subjected to a 60-day period of osteopenia fixation, after which the actual experimental protocol commenced. AKG was administered in the experimental solution for drinking at a concentration of 1.0?mol/l and a placebo (PLC) was used as a control solution. After 60?days of experimental treatment the rats in both experiements were sacrificed, the body weight recorded, and blood serum and isolated tibia were stored for further analysis. The bones were analyzed using tomography and densitometry, and for estimation of mechanical properties the 3-point bending test was used. Serum concentrations of osteocalcin and collagen type I crosslinked C-telopeptide were measured. The anabolic effects of AKG on bone during osteopenia development in Experiment-1 not only stopped the degradation of bone tissue, but also stimulated its mineralization. The usage of AKG in animals with established osteopenia (Experiment-2) was not able to prevent bone atrophy, but markedly reduced its intensity. The stimulation of tibia mineralization after AKG treatment has been also argued in healthy SHO animals. The results obtained prove the effectiveness of AKG usage in the prophylaxis and therapy of osteopenia and osteoporosis, induced by bilateral gonadectomy. Additionally, the results clearly prove that treatment with AKG improves the mineralization of bone tissue in healthy animals.     

Renal Mechanisms of Association between Fibroblast Growth Factor 1 and Blood Pressure

The fibroblast growth factor 1 (FGF1) gene is expressed primarily in the kidney and may contribute to hypertension. However, the biologic mechanisms underlying the association between FGF1 and BP regulation remain unknown. We report that the major allele of FGF1 single nucleotide polymorphism rs152524 was associated in a dose-dependent manner with systolic BP (P=9.65×10⁻⁵) and diastolic BP (P=7.61×10⁻³) in a meta-analysis of 14,364 individuals and with renal expression of FGF1 mRNA in 126 human kidneys (P=9.0×10⁻³). Next-generation RNA sequencing revealed that upregulated renal expression of FGF1 or of each of the three FGF1 mRNA isoforms individually was associated with higher BP. FGF1-stratified coexpression analysis in two separate collections of human kidneys identified 126 FGF1 partner mRNAs, of which 71 and 63 showed at least nominal association with systolic and diastolic BP, respectively. Of those mRNAs, seven mRNAs in five genes (MME, PTPRO, REN, SLC12A3, and WNK1) had strong prior annotation to BP or hypertension. MME, which encodes an enzyme that degrades circulating natriuretic peptides, showed the strongest differential coexpression with FGF1 between hypertensive and normotensive kidneys. Furthermore, higher level of renal FGF1 expression was associated with lower circulating levels of atrial and brain natriuretic peptides. These findings indicate that FGF1 expression in the kidney is at least under partial genetic control and that renal expression of several FGF1 partner genes involved in the natriuretic peptide catabolism pathway, renin-angiotensin cascade, and sodium handling network may explain the association between FGF1 and BP.     

The Formation of Cr-Al Spinel under a Reductive Atmosphere

In the present work, for the first time, the possibility of formation of CrAl₂O₄ was shown from the equimolar mixture of co-precipitated Al₂O₃ and Cr₂O₃ oxides under a reductive environment. The crystallographic properties of the formed compound were calculated using the DICVOL procedure. It was determined that it has a cubic crystal structure with space group Fd-3m and a unit cell parameter equal to 8.22(3) Å. The formed CrAl₂O₄ is not stable under ambient conditions and easily undergoes oxidation to α-Al₂O₃ and α-Cr₂O₃. The overall sequence of the phase transformations of co-precipitated oxides leading to the formation of spinel structure is proposed.     

Changes in spatial QRS-T angle and QTc interval in patients with traumatic brain injury with or without intra-abdominal hypertension

Introduction

Traumatic brain injury (TBI) affects cardiac electrical function, and several extra-cerebral factors, including intra-abdominal pressure (IAP), might further modulate this brain-heart interaction. The purpose of this study was to investigate the impact of TBI, and of increased IAP during TBI, on cardiac electrical function as measured by vectorcardiographic (VCG) variables.

Common Carotid Artery Remodeling Studied by Sonomorphological Criteria

BACKGROUND AND PURPOSE: Only a few attempts have been made to establish the impact of critical intima-media thickness (IMT) on narrowing of the lumen of the common carotid artery (CCA). In the present study, sonomorphological criteria have been used to assess how intima-media thickening in the CCA may influence the artery geometry. METHODS: High-resolution ultrasonography was employed in 233 patients (466 arteries) to quantify the selected parameters of CCA biometry: IMT, arterial lumen diameter (LD), interadventitial diameter (IAD), and outer artery diameter (OAD). RESULTS: With an increase of CCA IMT up to the critical point of 1.2 mm, the LD showed parallel compensatory increases. Above the inflection point of 1.3 mm, the lumen became progressively narrower proportionally to the increasing IMT. CONCLUSION: There are limits to the compensatory enlargement of the CCA lumen. Above the inflection point of CCA IMT of 1.3 mm, the artery lumen becomes progressively narrower with increasing IMT.     

The characteristics of fractures in Polish adolescents aged 16–20 years

The aim of the study was to identify associations between fractures in childhood and family, anthropometric and lifestyle factors. Among 1,246 subjects aged 16.3–20.6 years (539 boys, 707 girls), based on a questionnaire, 869 were fracture-free while 377 (30.26%) had fractures. Of those reporting fractures, 146 reported multiple fractures (12% of studied population, 39% of all fractures). More boys had fractures than girls (35.6% vs 24.9%, p < 0.001). Fracture sites included: forearm (37%), fingers (23%) wrist (16%), ankle (14%), humerus (10%), tibia (8%) clavicle (7%) and femoral shaft / neck (3%). Among adolescents with multiple fractures, 52% also reported fractures in at least one family member, compared with 29% of those without a fracture history. Fractures in siblings and mothers (but not fathers) accounted for 44% of the liability in adolescents fractures. Subjects with multiple fractures reported more time at the computer than those without fractures and reported more time participating in team sports, and 18.6% avoided milk, whereas 12.4% of those without fractures reported milk-free diets. Using a logistic regression model, none of the lifestyle factors, except for computer use, were independently associated with fractures. Fractures, particularly multiple fractures, are common in childhood and adolescence. Familial clustering of fractures suggests shared genetic and environmental factors are responsible.