Equilibrium fluctuations in myoglobin and lysozyme

The angular dependencies of inelastic intensities of Rayleigh scattering of Moessbauer radiation were measured for myoglobin and lysozyme (in the hydration range h = 0.05-0.7). The data were fitted within the framework of model, when two types of intraglobular motions were taken into account: individual motions of small side-chain groups and cooperative motions of segments. The best agreement with the experiment at h > 0.05 was obtained when individual motions of small groups together with the cooperative motions of alpha-helices and beta-sheets for lysozyme, and alpha-helices for myoglobin were considered. At further hydration (h = 0.45), mean-square displacements (x2) of both types of motions strongly increase with the increase in hydration degree, while the motions with a large correlation radius (not less than macromolecule radius) remain nearly the same as for h = 0.05. The results of the study of the radial distribution function deduced by Fourier-transform from the diffuse x-ray measurements together with RSMR data allow one to conclude that the water during protein hydration competes with the intramolecular hydrogen bonds, loosens the protein and increases the internal dynamics. Concurrently, water arranges the ordering of macromolecule, which takes the native structure at h = 0.4-0.7. The analysis of auto and cross-correlation functions of bending fluctuations of alpha-helices in the large domain of lysozyme performed by molecular dynamics allows one to come to the final conclusion that it is the difference in the structural organization of myoglobin and lysozyme and not the presence of SS-bonds in lysozyme macromolecule that is responsible for different structural fluctuations in these proteins.     

Laser spectroscopy for measuring the parameters of a plasma containing helium and argon

Laser spectroscopy diagnostics used in experiments on the PNX-U facility are described. The working gas was argon with an additive of helium. The 2³ P → 3³ D transition was excited by means of optical pumping, and helium fluorescence at wavelengths of 388 and 706.5 nm was observed. The Doppler temperature of helium atoms was determined by scanning the profile of the absorption line with the help of a tunable laser. The sum of the signals so obtained provides information on the local density of helium atoms. It was proposed to determine the local value of the electron density N _e (R) from the ratio between the fluorescence intensities at wavelengths of 388 and 706.5 nm. The ratio of these intensities as a function of N _e for He I was calculated in the collisional-radiative model, and relevant measurements of N _e in the PNX-U facility were performed. When diagnosing the argon component, the main attention was paid to measurements of the ion temperature T _i (R, t). In the course these measurements, anomalous heating of Ar II ions was revealed. The concentration of singly charged argon ions was estimated.     

Emission spectroscopy diagnostics of rare gases in the PNX-U facility

Results are presented from measurements of the electron temperature and neutral atom density in a low-temperature microwave plasma by the method of emission spectroscopy. The measurements were conducted in the PNX-U facility—a magnetic confinement system with a “magnetic wall.” Multichord measurements of plasma radiation at a wavelength of 750.37 nm were performed with the help of an absolutely calibrated monochromator. The neutral atom density was calculated using the collisional-radiative model. The degree of plasma ionization near the axis of the facility was found to be close to unity. The electron temperature of the argon plasma was measured from the relative intensities of the spectral lines of neutral helium injected in small amounts into the plasma (the so-called helium thermometer method). At a low microwave heating power, the results of these measurements agree well with the results of probe measurements.     

Immunologic autoagression in patients with diabetic retinopathy under type I diabetes mellitus

Presence of IgG autoantibodies to broad spectrum of tissues' antigens in patients with diabetic retinopathy under type I diabetes mellitus was studied. Increased levels of antibodies to different antigens were observed in 56% of patients. Increased levels of antibodies to hypophysis, denaturated DNA, and myelin basic protein were detected most frequently. Correlation in presence of autoantibodies of different specificity with diabetes length as well as with frequency of respiratory infections was established. There was relation between level of antibodies to DNA and increased permeability of microvascular network of retina as well as between presence of autoantibodies to myelin basic protein and encephalopathy in patients with type I diabetes mellitus.     

A study of protein structure changes during hydration by diffuse X-ray scattering. I. The intensity and the shape of "10-angstrom" maximum

The angle dependencies of diffuse x-ray scattering intensities were studied in a wide range of angles from 3 to 80 degrees for water-soluble and membrane proteins with a different structural organization: alpha-helical protein myoglobin, alpha-helical protein serum albumen, alpha + beta protein lysozyme, and transmembrane proteins of photosynthetic reaction centers (RC) from purple bacteria Rhodobacter sphaeroides, and Blastochlorii (Rhodopseudomonas) viridis containing cytocrome c, situated out side the membrane, and for H and L+M subunits of membrane protein of reaction center from Rb. sphaeroides for various hydration degrees. The hydration/dehydration process was studied for water-soluble proteins (within hydration range from h = 0.05 to h = 1). The hydration/dehydration process appears to be reversible. All water-soluble proteins show a 10 angstroms peak, and proteins of reaction center do not show this peak. A quantitative comparable study of the behaviour for of the 10 angstroms peak different proteins the degree of lysozyme hydration increases from h = 0.05 to h = 0.45, the protein structure slightly changes (most probably the motifoffolding), the structure of myoglobin in solution is slightly different from the structure in crystal. By taking into account the changes in the shape and intensity of the 10 angstroms peak only, it is impossible to make the conclusion about structural changes in other proteins studied. A correlation between the structural changes observed and dynamic and functional properties of proteins is discussed.     

Intercellular adhesion molecule-1 expression in human endometrium: implications for long term progestin only contraception

Background  

Neutrophils infiltrate the endometrium pre-menstrually and after long-term progestin only-contraceptive (LTPOC) treatment. Trafficking of neutrophils involves endothelial cell-expressed intercellular adhesion molecule (ICAM-1). Previous studies observed that ICAM-1 was immunolocalized to the endothelium of endometrial specimens across the menstrual cycle, but disagreed as to whether extra-endothelial cell types express ICAM-1 and whether ICAM-1 expression varies across the menstrual cycle.     

Innate immune defences in the human endometrium

The human endometrium is an important site of innate immune defence, giving protection against uterine infection. Such protection is critical to successful implantation and pregnancy. Infection is a major cause of preterm birth and can also cause infertility and ectopic pregnancy. Natural anti-microbial peptides are key mediators of the innate immune system. These peptides, between them, have anti-bacterial, anti-fungal and anti-viral activity and are expressed at epithelial surfaces throughout the female genital tract. Two families of natural anti-microbials, the defensins and the whey acidic protein (WAP) motif proteins, appear to be prominent in endometrium. The human endometrial epithelium expresses beta-defensins 1–4 and the WAP motif protein, secretory leukocyte protease inhibitor. Each beta-defensin has a different expression profile in relation to the stage of the menstrual cycle, providing potential protection throughout the cycle. Secretory leukocyte protease inhibitor is expressed during the secretory phase of the cycle and has a range of possible roles including anti-protease and anti-microbial activity as well as having effects on epithelial cell growth. The leukocyte populations in the endometrium are also a source of anti-microbial production. Neutrophils are a particularly rich source of alpha-defensins, lactoferrin, lysozyme and the WAP motif protein, elafin. The presence of neutrophils during menstruation will enhance anti-microbial protection at a time when the epithelial barrier is disrupted. Several other anti-microbials including the natural killer cell product, granulysin, are likely to have a role in endometrium. The sequential production of natural anti-microbial peptides by the endometrium throughout the menstrual cycle and at other sites in the female genital tract will offer protection from many pathogens, including those that are sexually transmitted.