Bilateral rapidly destructive coxopathy in rheumatoid arthritis.

Rapidly destructive coxopathy (RDC) is a rare type of coxarthritis marked by swift deterioration of the hip joint. Although its cause remains unclear, several pathophysiological mechanisms are proposed. To comprehensively analyze this poorly understood condition, a literature search was conducted focusing on associations of bilateral RDC and rheumatoid arthritis (RA). The problem of long-standing RA, bilateral RDC with a febrile episode that preceded a rapid decline in mobility and severe hip pain, with radiological assessment confirmed bilateral hip destruction, was presented. Rapidly destructive coxopathy, especially when linked to RA, poses diagnostic and therapeutic challenges. Our review confirmed by the clinical picture emphasizes the need for vigilance in RA patients with hip involvement and calls for further research to understand RDC's mechanisms and enhance clinical care.

Three-Dimensional Structural Stability and Local Electrostatic Potential at Point Mutations in Spike Protein of SARS-CoV-2 Coronavirus.

The contagiousness of SARS-CoV-2 ß-coronavirus is determined by the virus-receptor electrostatic association of its positively charged spike (S) protein with the negatively charged angiotensin converting enzyme-2 (ACE2 receptor) of the epithelial cells. If some mutations occur, the electrostatic potential on the surface of the receptor-binding domain (RBD) could be altered, and the S-ACE2 association could become stronger or weaker. The aim of the current research is to investigate whether point mutations can noticeably alter the electrostatic potential on the RBD and the 3D stability of the S1-subunit of the S-protein. For this purpose, 15 mutants with different hydrophilicity and electric charge (positive, negative, or uncharged) of the substituted and substituting amino acid residues, located on the RBD at the S1-ACE2 interface, are selected, and the 3D structure of the S1-subunit is reconstructed on the base of the crystallographic structure of the S-protein of the wild-type strain and the amino acid sequence of the unfolded polypeptide chain of the mutants. Then, the Gibbs free energy of folding, isoelectric point, and pH-dependent surface electrostatic potential of the S1-subunit are computed using programs for protein electrostatics. The results show alterations in the local electrostatic potential in the vicinity of the mutant amino acid residue, which can influence the S-ACE2 association. This approach allows prediction of the relative infectivity, transmissibility, and contagiousness (at equal social immune status) of new SARS-CoV-2 mutants by reconstruction of the 3D structure of the S1-subunit and calculation of the surface electrostatic potential.

Omicron Coronavirus: pH-Dependent Electrostatic Potential and Energy of Association of Spike Protein to ACE2 Receptor.

The association of the S-protein of the SARS-CoV-2 beta coronavirus to ACE2 receptors of the human epithelial cells determines its contagiousness and pathogenicity. We computed the pH-dependent electric potential on the surface of the interacting globular proteins and pH-dependent Gibbs free energy at the association of the wild-type strain and the omicron variant. The calculated isoelectric points of the ACE2 receptor (pI 5.4) and the S-protein in trimeric form (pI 7.3, wild type), (pI 7.8, omicron variant), experimentally verified by isoelectric focusing, show that at pH 6-7, the S1-ACE2 association is conditioned by electrostatic attraction of the oppositely charged receptor and viral protein. The comparison of the local electrostatic potentials of the omicron variant and the wild-type strain shows that the point mutations alter the electrostatic potential in a relatively small area on the surface of the receptor-binding domain (RBD) of the S1 subunit. The appearance of seven charge-changing point mutations in RBD (equivalent to three additional positive charges) leads to a stronger S1-ACE2 association at pH 5.5 (typical for the respiratory tract) and a weaker one at pH 7.4 (characteristic of the blood plasma); this reveals the reason for the higher contagiousness but lower pathogenicity of the omicron variant in comparison to the wild-type strain.

Composite Hydrogels with Included Solid-State Nanoparticles Bearing Anticancer Chemotherapeutics.

Hydrogels have many useful physicochemical properties which, in combination with their biocompatibility, suggest their application as a drug delivery system for the local and prorogated release of drugs. However, their drug-absorption capacity is limited because of the gel net's poor adsorption of hydrophilic molecules and in particular, hydrophobic molecules. The absorption capacity of hydrogels can be increased with the incorporation of nanoparticles due to their huge surface area. In this review, composite hydrogels (physical, covalent and injectable) with included hydrophobic and hydrophilic nanoparticles are considered as suitable for use as carriers of anticancer chemotherapeutics. The main focus is given to the surface properties of the nanoparticles (hydrophilicity/hydrophobicity and surface electric charge) formed from metal and dielectric substances: metals (gold, silver), metal-oxides (iron, aluminum, titanium, zirconium), silicates (quartz) and carbon (graphene). The physicochemical properties of the nanoparticles are emphasized in order to assist researchers in choosing appropriate nanoparticles for the adsorption of drugs with hydrophilic and hydrophobic organic molecules.

Protein-Mineral Composite Particles with Logarithmic Dependence of Anticancer Cytotoxicity on Concentration of Montmorillonite Nanoplates with Adsorbed Cytochrome c.

Montmorillonite (MM) colloid nanoplates have high adsorption capacity due to their large size/thickness ratio, which allows them to be used as carriers for drug delivery. Upon adsorption of the mitochondrial protein cytochrome c (cytC) onto MM plates, the composite cytC-MM particles acquire anticancer properties because of the ability of cancer cells to phagocytize submicron particles (in contrast to the normal cells). In this way, exogenous cytC can be introduced into tumor cells, thereby triggering apoptosis-an irreversible cascade of biochemical reactions leading to cell death. In the present study, we investigated the physicochemical properties of cytC-MM particles as a function of the cytC concentration in the suspension, namely, the electrophoretic mobility, the mass increment of MM monoplates upon cytC adsorption, the ratio of the adsorbed to the free cytC in the bulk, the protein density on the MM's surface, the number of cytC globules adsorbed on an MM monoplate, the concentration of cytC-MM composite particles in the suspension, and the dependence of cytotoxicity on the cytC-MM particle concentration. For this purpose, we used microelectrophoresis, static and electric light scattering, and a colon cancer cell culture to test the cytotoxic effects of the cytC-MM suspensions. The results show that the cytotoxicity depends linearly on the logarithm of the particle concentration in the cytC-MM suspension reaching 97%.

Spontaneous and Electrically Induced Anisotropy of Composite Agarose Gels.

Agarose gels containing and not bacteriorhodopsin purple membranes (incorporated before gelling) manifest spontaneous optical anisotropy. The dependencies of the anisotropy on the agarose concentration and time have been studied. The rise in the anisotropy is explained by the predominant orientation of the agarose fibers during the gelling and subsequent deformation of the gel net. In the electric field, additional optical anisotropy rises, which is caused by the orientation of the membranes. A procedure has been developed to separate electrically induced and spontaneous anisotropy in composite gels. The isoelectric points and surface electric potential of bacteriorhodopsin trimer and purple membranes are calculated by the method of protein electrostatics to explain their electric asymmetry, which leads to perpendicular orientation in the direct electric field and longitudinal in the kilohertz sinusoidal field. The results allow for an increase in the separation capability of composite gels of electrophoresis for macromolecules with different sizes by applying an appropriate electric field to modulate the effective pore size.

Electrooptical determination of the isoelectric point of globular proteins: Cytochrome c adsorbed on montmorillonite nanoplates.

The purpose is to study the capability of the electric light scattering to determine the point of zero charge of native protein macromolecules adsorbed on colloid particles at low ionic strength and without using buffers. The chosen protein and particles are cytochrome c (cytC, globular haemoproteid) and montmorillonite (MM, negatively charged plate-like crystal). The pH-dependence of the electric polarizability γ(pH) in the range pH 6-11 shows minimum which coincides with the isoelectric point determined by measuring the electrophoretic mobility µ(pH) of the cytC-MM particles.

Isoelectric point of free and adsorbed cytochrome c determined by various methods.

The purpose is to determine the isoelectric point (IEP) pIµ of cytochrome c (cytC, a globular haemoproteid) adsorbed on montmorillonite (MM, plate-like colloid particles) by microelectrophoresis and to compare the pIµ value with pIf9.44 measured by isoelectric focusing in gel with covalently linked ampholytes, and with pInz10.0-10.6 of free cytC globule calculated by three programs for pH-dependent net charge nz using the crystallographic structure of cytC. The pH-dependence of the electrophoretic mobility µ(pH) in the range pH 6-11 shows out that IEP of cytC-MM particles appears at pH 9.35. The near courses of µ(pH) and nz(pH) reveal that the pH-independent negative charge of the MM substrate is hydrodynamically shielded by the adsorbed protein globules. The nearness of IEP and pIf allows attributing IEP value of cytC-MM particles to the isoelectric point pIµ of cytC. A short survey for pI of cytC reported in the literature since 1941 shows out that pI is dispersed in the range pH 9.0-10.65 although cytC is used now as pIf marker with well known IEP; the reason for that and the imperfections of the employed methods are discussed.

Adsorption of cytochrome c on montmorillonite nanoplates: protein concentration dependence.

Cytochrome c [cytC] is a mitochondrial hemoprotein functioning as electron carrier in the respiratory chain of the biological cells. Being adsorbed on colloid particles cytC can be introduced in the cells by phagocytoses. In the present work we study the adsorption of cytC on montmorillonite (MM) particles combining the electro-optic and electrophoretic techniques. MM particles were chosen as nanoplates having negative pH-independent charge and high ratio surface/mass. The measurements were done at pH 6.5 where cytC globule is positively charged. The main employed method is the electric light scattering based on orientation of colloid particles in sinusoidal electric field. Interfacial electric polarizability was obtained from the degree of orientation at steady-state and the particle size - from the relaxation time after the field switching off. Microelectrophoresis was used to monitor the alteration of the surface charge at protein adsorption. The cytC-concentration dependence of the polarizability and the mobility shows out that the total (net) charge of cytC-MM complex turns its sign from negative to positive, the isoelectric point appears at 5:3 mg/mg (0.135 mol/kg) cytC/MM and saturated protein adsorption is reached at additional twofold increasing of cytC/MM ratio. The suspension is stable at low and high protein concentrations, at intermediate ones aggregation arises.

Prevalence of JC polyomavirus genomic sequences from the large T-antigen and non-coding control regions among Bulgarian patients with primary brain tumors.

A total of 111 fresh brain biopsies from patients with primary brain tumors were examined for JC polyomavirus sequences from the Large T antigen encoding region (LT) and the viral non-coding control region (NCCR). SYBR Green and TaqMan real-time polymerase chain reaction assays were used. In the glioblastoma group of 39 patients 48.7% were positive for LT sequences. Among the astrocytoma group (19 patients) and the oligodendroglioma group (12 patients) 31.6% and 33.3% were also positive. The prevalence of LT genomic sequences among the other groups was as follows: in 2 out of 3 oligoastrocytomas; in 3 out 5 gangliogliomas; in 2 out of 5 meduloblastomas; in 1 out 3 pineocytomas; and in none of the tested 5 ependimomas. All positive samples had a late threshold cycle that varied from 36 to 49, indicative of very low starting viral number. Only 21 of all the 111 samples were positive for NCCR. Low copy number in range of 10-1,000 was present. Notably, only 8 of all NCCR positive specimens were also LT positive. It might be suggested that the disproportion between the results for LT and NCCR is either due to clonally integrated LT fragments, with loss of genetic material, or changes in the NCCR. The latter would alter the productive course of the infection and may establish a premise for continuous interaction of viral regulatory proteins with cell molecules that are responsible for the control of the cell cycle. This may lead subsequently to malignant transformation.

Simultaneous bilateral breast carcinomas: a category with frequent coexpression of HER-2 and ER-alpha, high Ki-67 and bcl-2, and low p53.

The aim of this study was to evaluate clinicopathological characteristics and immunophenotypes of simultaneous bilateral adenocarcinomas of the breast and their axillary metastases. Immunohistochemical analysis and in situ hybridization were performed using formalin-fixed/paraffin-embedded tissues. In total, 15 primary and 9 metastatic tumors from 8 patients were evaluated. The expression of estrogen receptor-alpha (ER-alpha), progesterone receptor (PR), Ki 67, p53, bcl-2, and bax were evaluated by immunohistochemistry. Her2 gene amplification was evaluated by chromogenic in situ hybridization (CISH). Four patients were younger that 40 years of age (mean 47 years). Six patients had pleomorphic lobular carcinoma in 1 breast. Four of these had invasive ductal carcinoma in the contralateral breast. One patient had atypical medullary carcinoma in both breasts and 1 patient had atypical medullary carcinoma in 1 breast and pleomorphic lobular carcinoma in the other. The phenotype of the primary tumors and corresponding metastatic tumors was similar for the expression of ER-alpha (p=0.001), PR (p=0.03), and HER-2 (p=0.018). While strong coexpression of HER-2 and ER-alpha is exceptional in hereditary breast carcinoma and sporadic breast carcinoma, 6/8 (75%) patients in this study had tumors with strong coexpression of HER-2 and ER-alpha. P53 protein expression was found in only 2/15 (13%) primary tumors, which is in contrast to BRCA1-related hereditary bilateral breast carcinomas, which often express p53 protein. Most of the patients presented with axillary metastases and had very aggressive course. Characteristically, the tumors showed high levels of expression of ER-alpha and Her2 amplification, were bcl-2 positive, and had high Ki-67 fraction. However, in patients with atypical medullary carcinoma there was no expression of ER-alpha or amplification of Her-2.