Evaluation of the professional qualities of operators working with computer displays

The influence of spatio-temporal factors (spatial heterogeneity of distribution of the numbers sought for in the matrix of data, processes of learning and development of fatigue, periodic attention oscillations) of the character of solving the task of searching the numbers in a matrix of 176 three-figure numbers (16 lines, 11 columns) was studied in 39 operators. The possibility was shown to use the characteristics obtained for evaluation of professionally important abilities of an operator working at the display.     

Nucleomeric organization of chromatin

Chromatin in the nuclei fixed in tissue and in the nuclei isolated by low ionic strength solutions in the presence of Mg2+ is represented by globular (nucleomeric) fibrils, 20-25 nm in diameter. The staphylococcal or endogenous nuclear nuclease splits the chromatin fibrils resulting in fragments corresponding to nucleomers and their multimers. Upon removal of firmly bound Mg2+ the nucleomers unfold to form chains consisting of 4-6-8 nucleosomes. Mild hydrolysis of nuclear chromatin by staphylococcal nuclease results in a split-off of mono-, di- and trimers of nucleomers sedimenting in a sucrose density gradient in the presence of EDTA as particles with the sedimentation coefficients of 37, 47 and 55S, respectively. The sedimentation coefficient for the mononucleomer in a sucrose density gradient with MgCl2 is 45S. Determination of the length of DNA fragments of chromatin split-off by staphylococcal nuclease showed that the nucleomer consists of 8 nucleosomes, while the dimer and trimer of the nucleomer consists of 14-16 and 21-24 nucleosomes, respectively. The nucleomeric monomer undergoes structural transition from the compact (45S) to the "loose" state (37S) after removal of Mg2+. This transition is completely reversible, when the nucleomer contains histone H1. The removal of the latter or dialysis of the nucleomer against EDTA in low ionic strength solutions results in a complete unfolding of the nucleomer into a nucleosomal chain fragment. A model for the nucleomer fibril structure in which the helical organization of the nucleosomal chain in the nucleomer (2 turns with 4 nucleosomes in each) is alternated with the impaired helical bonds between the nucleomers is discussed. The functional significance of the nucleomeric organization of chromatin may be an additional restriction of the site-specific recognition of DNA in chromatin with the possibility of local (at the level of one nucleomer) changes in chromatin conformation excluding this restriction.     

Severe Painful Vaso-Occlusive Crises and Mortality in a Contemporary Adult Sickle Cell Anemia Cohort Study

Background

Frequent painful vaso-occlusive crises (VOCs) were associated with mortality in the Cooperative Study of Sickle Cell Disease (CSSCD) over twenty years ago. Modern therapies for sickle cell anemia (SCA) like hydroxyurea are believed to have improved overall patient survival. The current study sought to determine the relevance of the association between more frequent VOCs and death and its relative impact upon overall mortality compared to other known risk factors in a contemporary adult SCA cohort.

Methods

Two hundred sixty four SCA adults were assigned into two groups based on patient reported outcomes for emergency department (ED) visits or hospitalizations for painful VOC treatment during the 12 months prior to evaluation.

Results

Higher baseline hematocrit (p = 0.0008), ferritin (p = 0.005), and HDL cholesterol (p = 0.01) were independently associated with 1 or more painful VOCs requiring an ED visit or hospitalization for acute pain. During a median follow-up of 5 years, mortality was higher in the ED visit/hospitalization group (relative risk [RR] 2.68, 95% CI 1.1-6.5, p = 0.03). Higher tricuspid regurgitatant jet velocity (TRV) (RR 2.41, 95% CI 1.5-3.9, p < 0.0001), elevated ferritin (RR 4.00, 95% CI 1.8-9.0, p = 0.001) and lower glomerular filtration rate (RR=2.73, 95% CI 1.6-4.6, p < 0.0001) were also independent risk factors for mortality.

Conclusions

Severe painful VOCs remain a marker for SCA disease severity and premature mortality in a modern cohort along with other known risk factors for death including high TRV, high ferritin and lower renal function. The number of patient reported pain crises requiring healthcare utilization is an easily obtained outcome that could help to identify high risk patients for disease modifying therapies.

Trial Registration

ClinicalTrials.gov NCT00011648 http://clinicaltrials.gov/     

Anomalous change in the specific conductivity in lipoproteins at around physiologic temperatures

Studying the temperature dependence of conductivity sigma of rat and human lipoproteins and apoprotein A-I fractions revealed an anomalous region in the range of temperatures (35-38) +/- 0.5 degree C. The activation energy delta H and temperature coefficient sigma (delta sigma/delta T) on both sides of Tc and the heat of transition (delta H of transition) were calculated. In high-density human lipoproteins and apoA-I, the delta H value was found to be very low. Some mechanisms of interaction of hydrocortizone with high-density lipoproteins and apoA-I were studied by using IR-spectroscopy and conductometry were studied. It was found that the hormone considerably increases the portion of alpha-helices and beta-structures in these proteins (coil<-->alpha-helix and coil<-->beta-structure transitions). In this case, delta H value of the transition increases 13-fold; in addition, the abnormal region in apoA-I shifts 1-2 degrees C downwards. The anomalous changes in conductivity in the range of physiological temperatures in all lipoprotein fractions including apoA-I are probably related to structural phase transitions both in proteins and in phospholipids. Since the delta H value of the transition in human high-density lipoproteins is small, it is assumed that, in phospholipids of these particles, an orientation transition of the A<-->C smectic type takes place, which is assigned to the second-order phase transition. The structural transition in apoA-I can probably also be assigned to the second-order phase transition since the enthalpia of the transition is very small; presumably, this transition is related to changes in symmetry due to changes in the secondary structure (coil<-->beta-tructure transition).