Heart Rate Variability and Accelerometry as Classification Tools for Monitoring Perceived Stress Levels-A Pilot Study on Firefighters.

Chronic stress is the main cause of health problems in high-risk jobs. Wearable sensors can become an ecologically valid method of stress level assessment in real-life applications. We sought to determine a non-invasive technique for objective stress monitoring. Data were collected from firefighters during 24-h shifts using sensor belts equipped with a dry-lead electrocardiograph (ECG) and a three-axial accelerometer. Levels of stress experienced during fire incidents were evaluated via a brief self-assessment questionnaire. Types of physical activity were distinguished basing on accelerometer readings, and heart rate variability (HRV) time series were segmented accordingly into corresponding fragments. Those segments were classified as stress/no-stress conditions. Receiver Operating Characteristic (ROC) analysis showed true positive classification as stress condition for 15% of incidents (while maintaining almost zero False Positive Rate), which parallels the amount of truly stressful incidents reported in the questionnaires. These results show a firm correspondence between the perceived stress level and physiological data. Psychophysiological measurements are reliable indicators of stress even in ecological settings and appear promising for chronic stress monitoring in high-risk jobs, such as firefighting.

The Role of Interhemispheric Interactions in Cortical Plasticity.

Despite the fact that there is a growing awareness to the callosal connections between hemispheres the two hemispheres of the brain are commonly treated as independent structures when peripheral or cortical manipulations are applied to one of them. The contralateral hemisphere is often used as a within-animal control of plastic changes induced onto the other side of the brain. This ensures uniform conditions for producing experimental and control data, but it may overlook possible interhemispheric interactions. In this paper we provide, for the first time, direct proof that cortical, experience-dependent plasticity is not a unilateral, independent process. We mapped metabolic brain activity in rats with 2-[14C] deoxyglucose (2DG) following experience-dependent plasticity induction after a month of unilateral (left), partial whiskers deprivation (only row B was left). This resulted in ∼45% widening of the cortical sensory representation of the spared whiskers in the right, contralateral barrel field (BF). We show that the width of 2DG visualized representation is less than 20% when only contralateral stimulation of the spared row of whiskers is applied in immobilized animals. This means that cortical map remodeling, which is induced by experience-dependent plasticity mechanisms, depends partially on the contralateral hemisphere. The response, which is observed by 2DG brain mapping in the partially deprived BF after standard synchronous bilateral whiskers stimulation, is therefore the outcome of at least two separately activated plasticity mechanisms. A focus on the integrated nature of cortical plasticity, which is the outcome of the emergent interactions between deprived and non-deprived areas in both hemispheres may have important implications for learning and rehabilitation. There is also a clear implication that there is nothing like "control hemisphere" since any plastic changes in one hemisphere have to have influence on functioning of the opposite one.

Spreading Depressions and Periinfarct Spreading Depolarizations in the Context of Cortical Plasticity.

Studies of cortical function-recovery require a comparison between normal and post-stroke conditions that lead to changes in cortical metaplasticity. Focal cortical stroke impairs experience-dependent plasticity in the neighboring somatosensory cortex and usually evokes periinfarct depolarizations (PiDs) - spreading depression-like waves. Experimentally induced spreading depressions (SDs) affect gene expression and some of these changes persist for at least 30 days. In this study we compare the effects of non-stroke depolarizations that impair cortical experience-dependent plasticity to the effects of stroke, by inducing experience-dependent plasticity in rats with SDs or PiDs by a month of contralateral partial whiskers deprivation. We found that whiskers' deprivation after SDs resulted in normal cortical representation enlargement suggesting that SDs and PiDs depolarization have no influence on experience-dependent plasticity cortical map reorganization. PiDs and the MMP-9, -3, -2 or COX-2 proteins, which are assumed to influence metaplasticity in rats after stroke were compared between SDs induced by high osmolarity KCl solution and the PiDs that followed cortical photothrombotic stroke (PtS). We found that none of these factors directly caused cortical post-stroke metaplasticity changes. The only significant difference between stoke and induced SD was a greater imbalance in interhemispheric activity equilibrium after stroke. The interhemispheric interactions that were modified by stroke may therefore be promising targets for future studies of post-stroke experience-dependent plasticity and of recuperation studies.

[Risk factors of retinopathy of prematurity in newborns treated in neonatal intensive care unit of University Children's Hospital Collegium Medicum Jagiellonian University]. / Czynniki ryzyka rozwoju retinopatii wczesniaków u pacjentów Oddzialu Patologii i Intensywnej Terapii Noworodka Uniwersyteckiego Szpitala Dzieciecego Collegium Medium Uniwersytetu Jagiellonskiego.

BACKGROUND: A persistent progress in perinatal care and a large increase in infants' survival rate have been observed recently. As a result, the number of neonates requiring ophthalmologic examinations due to retinopathy of prematurity (ROP) increased as well. METHOD: A retrospective survey including 206 neonates with mean birth weight 1342 g and mean gestational age 30 weeks. MATERIAL: Three groups: 1) without ROP--165 infants (80.1%); 2) with ROP not requiring treatment--13 infants (6.3%); 3) with prethreshold and threshold ROP requiring cryotherapy--28 infants (13.6%) were analysed. RESULTS: Threshold ROP was not observed in infants with gestational age > 32 weeks and/or birth weight > 1500 g. Cryotherapy was applied between the 6th and 18th weeks of life (Mo: 12). The procedure was applied at postmenstrual age between the 34th and 45th weeks of life (Mo: 38). The correlation of ROP with the following factors was observed: length of mechanical ventilation (Me in the studied groups: 6; 22; 33 days respectively; p < 0.01), length of oxygen therapy (Me: 27; 58; 70 days; p < 0.01), number of blood transfusions in first month of life (Me: 2; 4; 4; p < 0.01), minimum pO2 (average: 37.2; 30.2; 29.2 mmHg p < 0.01), pO2 oscillation (measured as SD) (Me: 10.25; 13.2; 15.4 mmHg p < 0.016) and maximal pCO2 (average: 52.5; 56.8; 66.5 p < 0.01) between the 2nd and 4th weeks of life. CONCLUSION: Monitoring of pO2 and pCO2 in infants in the 1st month of life reduce the risk of ROP development. Infants born before the 32nd week of gestational age belong to high risk group and require very systematic ophthalmologic examination. The current prophylactic examination schedule for ROP for more mature infants may be changed.

Preparation and characterization of genipin cross-linked porous chitosan-collagen-gelatin scaffolds using chitosan-CO2 solution.

Novel porous scaffolds composed of chitosan, collagen and gelatin were prepared by the multistep procedure involving final freeze-drying and characterized. To eliminate the need for residual acid removal from the material after drying, carbon dioxide saturation process was used for chitosan blend formulation. The use of CO2 for chitosan dissolution made the scaffold preparation process more reproducible and economically sustainable. Genipin was applied to stabilize the structure of the scaffolds and those crosslinked at a level of 7.3% exhibited a homogenous porous structure (33.1%), high swelling capacity (27.6g/g for wound exudate like medium; 62.5 g/g for water), and were stable under cyclic compression. The values of other investigated parameters: dissolution degree (30%), lysozyme-induced degradation (5% after 168 h), good antioxidant properties (DPPH, ABTS, Fe(2+) assays) and especially very low in vitro cytotoxicity against fibroblasts (103%, MTT assay), were highly advantageous for possible biomedical applications of the novel materials.