Learning characteristics and long-term memory in rhesus macaques

The use of entropy of choices distribution in studying the processes of learning and long-term memory in rhesus monkeys during differentiation of periodic and non-periodic visual stimuli, showed that the transition from the unlearned state to the learned one proceeds not gradually but in two stages; the first stage--the accumulation of information and externally random behaviour, the second stage--rapid transition to the learned behaviour. For "filters" selective to spatial frequency, the change of stimuli orientation leads to an increase of the behaviour entropy. For "filters" selective to the bar width, the entropy practically does not change. During prolonged storage of acquired information, in the long-term memory, its partial loss takes place leading to an increase of the behaviour entropy. The difference between the entropy determined directly after the learning and that determined again after a prolonged storage of the memorized habit characterizes the quantity of information lost during the storage period.     

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/     

Delivery of CRISPR/Cas Components into Higher Plant Cells for Genome Editing

Russian Journal of Plant Physiology - CRISPR/Cas genome editing of plants is realized in three basic variants, including knockout mutations as indels, insertion of alien DNA fragments, and base...     

Effect of initial (spontaneous) arterial pressure on systemic hemodynamic orthostatic responses

In anesthetized rats, a reverse linear correlation of arterial pressure (AP) shifts was found within the range of initial AP over 95 mm Hg under the head-up tilts at 30 and 45 degrees. Within the range beneath 95 mm Hg this correlation was transformed into the direct one. Under 60 degrees tilt such correlation only occurred within the range beneath 95 mm Hg. The direction and degree of the arterial system responsiveness seems to depend on the tilt value as well as on the range of the initial AP.     

Effects of medium viscosity on kinetics of the enzymatic reaction catalyzed by bacterial RNase

Effects of medium viscosity on kinetic parameters of poly(U) hydrolysis catalyzed by RNase from Bac. intermedius 7P (binase) were studied in solutions of sucrose (4-50 wt. %) and glycerol (35-62 wt. %) in Tris--sodium acetate buffer (pH 7.5) at 25 degreesC. The rate constant of reaction kcat was practically unchanged over a wide range of viscosities (1-15 cP for sucrose and 2.5-3 cP for glycerol). In glycerol solutions, kcat slightly increased with viscosity increase from 4 to 10 cP. Addition of NaCl to the buffer medium resulted in an inhibitory effect of Na+ on kcat, prevented by 50% sucrose or 60% glycerol. It is concluded that binase-catalyzed poly(U) cleavage occurs through a "tense"-substrate mechanism, similarly to reactions catalyzed by alpha-chymotrypsin, trypsin, and laccase.     

A web server to locate periodicities in a sequence

Summary : FT is a tool written in C++, which implements the Fourier analysis method to locate periodicities in aminoacid or DNA sequences. It is provided for free public use on a WWW server with a Java interface. Availability : The server address is http://o2.db. uoa.gr/FT Contact : shamodr@atlas.uoa.gr      

Sex-dependent differences in parameters of a long-term pain caused by inflammatory focus in prenatally stressed newborn rats

In experiments on the 7-day-old female and male Long-Evans rat pups, for the first time, there was studied effect of prenatal (immobilization) stress on dynamics of nociceptive behavioral response caused by an inflammatory focus. The nociceptive sensitivity was evaluated for 1 h by the number of 7-day-old organized at the spinal level in response to injection of formalin (10%, 10 microl) to the posterior leg sole. Control rat pups were not submitted to any prenatal stress; in these animals the response in the formalin test was found to be represented by one phase. It the prenatally stressed rat pups the studied patterns were organized into two phases characteristic of the definitive type of response. At the period between them (during interphase), the nociceptive behavior was absent. At the second, tonic phase the number of flexes+shakes in the prenatally stressed males was statistically significantly higher than in the prenatally stressed females, which indicates a sensitization of the neurons involved in the tonic pain chains in male individuals. Thus, the data obtained on prenatally stressed animals confirm the previous data about immaturity of the mechanisms mediating the second phase of response in the formalin test in the 7-day-old rat pups. An important fact is revealed which indicates that in the prenatally stressed rat pups of the same age the second phase of response is already obvious. Mechanisms underlying the behavioral response caused by the inflammatory focus in the formalin test in the number flexes + shakes old stressed rat pups are characterized by sexual dimorphism: the pain sensitivity in males at the second phase of response is statistically significantly higher than in females.     

Barnase and binase: twins with distinct fates

RNases are enzymes that cleave RNAs, resulting in remarkably diverse biological consequences. Many RNases are cytotoxic. In some cases, they attack selectively malignant cells triggering an apoptotic response. A number of eukaryotic and bacterial RNase-based strategies are being developed for use in anticancer and antiviral therapy. However, the physiological functions of these RNases are often poorly understood. This review focuses on the properties of the extracellular RNases from Bacillus amyloliquefaciens (barnase) and Bacillus intermedius (binase), the characteristics of their biosynthesis regulation and their physiological role, with an emphasis on the similarities and differences. Barnase and binase can be regarded as molecular twins according to their highly similar structure, physical-chemical and catalytic properties. Nevertheless, the 'life paths' of these enzymes are not the same, as their expression in bacteria is controlled by diverse signals. Binase is predominantly synthesized under phosphate starvation, whereas barnase production is strictly dependent on the multifunctional Spo0A regulator controlling sporulation, biofilm formation and cannibalism. Barnase and binase also have some distinctions in practical applications. Barnase was initially suggested to be useful in research and biotechnology as a tool for studying protein-protein interactions, for RNA elimination from biological samples, for affinity purification of RNase fusion proteins, for the development of cloning vectors and for sterility acquisition by transgenic plants. Binase, as later barnase, was tested for antiviral, antitumour and immunogenic effects. Both RNases have found their own niche in cancer research as a result of success in targeted delivery and selectivity towards tumour cells.