Virtual Reality-Induced Modification of Vestibulo-Ocular Reflex Gain in Posturography Tests.

Background: The aim of the study was to demonstrate the influence of virtual reality (VR) exposure on postural stability and determine the mechanism of this influence. Methods: Twenty-six male participants aged 21-23 years were included, who underwent postural stability assessment twice before and after a few minute of single VR exposure. The VR projection was a computer-generated simulation of the surrounding scenery. Postural stability was assessed using the Sensory Organization Test (SOT), using Computerized Dynamic Posturography (CDP). Results: The findings indicated that VR exposure affects the visual and vestibular systems. Significant differences (p < 0.05) in results before and after VR exposure were observed in tests on an unstable surface. It was confirmed that VR exposure has a positive influence on postural stability, attributed to an increase in the sensory weight of the vestibular system. Partial evidence suggested that the reduction in vestibulo-ocular reflex (VOR) reinforcement may result in an adaptive shift to the optokinetic reflex (OKR). Conclusions: By modifying the process of environmental perception through artificial sensory simulation, the influence of VR on postural stability has been demonstrated. The validity of this type of research is determined by the effectiveness of VR techniques in the field of vestibular rehabilitation.

Investigations Concerning the Influence of Sleep Disorders on Postural Stability in Young Men.

Lack of sleep is a factor that disrupts the receptors' reception of information from the environment and contributes to the emergence of problems with maintaining balance. The main aim of the study was to determine whether sleep disorders affect postural stability in young men. The study participants were 76 male students who were divided into groups with good and poor sleep quality. The division was made based on the results obtained from the questionnaire of the Pittsburgh Sleep Quality Index (PSQI). In each group, postural stability had been tested using three main tests: Sensory Organization Test (SOT); Motor Control Test (MCT); and Adaptation Test (ADT). The results of the analysis show that the obtained results differ in the examined groups under the SOT test. Different values of the tested parameters were noted among people with poor sleep quality and compared with the values of those who sleep well, which translates into a difference in the ability to maintain balance. The greatest impact is observed when using visual and a vestibular system to maintain a stable posture. It was confirmed that the lack of sleep significantly disturbs postural stability.

The influence of caffeine administered at 10°C on bone tissue development.

INTRODUCTION AND OBJECTIVE: Caffeine is a natural methylxanthine widespread throughout the food industry. Many research studies have shown that caffeine readily crosses the placenta causing teratogenic and embryotoxic effects. The objective of this study was to assess the influence of caffeine, administered at 10°C, on the development of a rat's bone tissue, with particular reference to elemental bone composition using an X-ray microprobe. MATERIALS AND METHODS: The research was conducted on white rats of the Wistar strain. The fertilized females were divided into two groups: an Experimental Group (Group E) and a Control Group (Group C). The females in Group E were given caffeine orally (at 10°C) in 30 mg/day doses from the 8(th) - 21(st) day of pregnancy. The females in Group C were given water at the same temperature. The foetuses were used to assess the growth and mineralization of the skeleton. Qualitative analysis of the morphology and mineralization of bones was conducted using the alcian-alizarin method. For calcium and potassium analysis, an X-ray microprobe was used. RESULTS: By staining the skeleton using the alcian-alizarin method, changes in 47 Group E foetuses were observed. The frequency of the development variants in the Group E rats was statistically higher, compared with Group C. CONCLUSIONS: On the basis of these results, it can be concluded that caffeine in high doses disturbs the development of bone tissue. An additional factor which enhances the adverse effects of this substance on bone tissue is the temperature of the administered solution (10(o)C). In the Experimental Group, a significant decrease in the calcium level, as well as an increase in the potassium level, was observed. The X-ray microprobe can be a perfect complement to the methods which enable determination of the mineralization of osseous tissue.

The effects of caffeine administered at different temperatures on foetal development.

An easy access to products containing caffeine makes it widely consumed to excess by the general population, including pregnant women. Beverages containing caffeine are consumed at different temperatures (iced, hot, room temperature). Caffeine easily passes through biological membranes, including the blood-brain barrier, the placental barrier, and can also enter the amniotic fluid, breast milk and semen. The aim of this study was to evaluate the relationship between caffeine's developmental toxicity, and the solution's temperature (both low and high) administered to pregnant female rats. Fertilized females were randomly divided into two main groups: an experimental (E) and a control group (C). The experimental groups received caffeine (30mg/day) in 10 (E1), 25 (E2) and 45(o)C (E3). The females in the control group were given water at the same temperature (C1, C2 and C3). On the day 21 of pregnancy, the pregnant females were killed by decapitation, using a specially prepared laboratory guillotine, after which the mothers' internal organs were weighed. Additionally, the offspring were examined using standard teratological methods. The study found that caffeine administered to pregnant females at a dose of 30mg/day and at the temperatures of 10°C, 25°C or 45°C did not produce any teratogenic effects. The only sign of its adverse effect was the appearance of developmental abnormalities in the form of haematomas and saturated bleeding in the internal organs. These changes most frequently occurred in foetuses of females which received caffeine at 10°C or 45°C.

The human balance system and gender.

The human body balance system is a complex system of organs and mechanisms, which generate postural reactions to counter the displacement from the equilibrium position of the body centre of gravity, and which control eye movement in order to maintain a stable image of the environment. Computerised Dynamic Posturography (CDP) allows for a quantitative and objective assessment of the sen- sory and motor components of the body balance control system as well as of the integration and adaptive mechanisms in the central nervous system. The aim of this study was to determine the differences, when maintaining body balance, based on the gender of young, healthy people using CDP. The study was carried out on a group of 43 healthy subjects by comparing the effectiveness of the balance system in 22 women and 21 men aged between 20 and 26 years, between 171 and 177 cm in height, and without any clinical symptoms of balance disorders. The men and women were selected such that they did not differ significantly in height and BMI. Using the Equitest posturograph manufactured by NeuroCom International Inc. the following tests were performed: Sensory Organisation Test (SOT), Motor Control Test (MCT) and the Adaptation Test (ADT). The gender of young healthy individuals without any clinical symptoms of balance disorders also does not affect the effectiveness of the sensory system and the use of this signal in maintaining body balance.

Influence of caffeine administered at 45 °C on bone tissue development.

INTRODUCTION AND OBJECTIVE: Caffeine is one of the world's most commonly ingested alkaloids which easily permeates the placenta. The teratogenic and embryotoxic influence of large doses of caffeine has been established in many experimental studies on animals. The objective of this work was to assess the influence of caffeine, administered at 45 °C, on the development of the bone tissue of rats, with particular reference to elemental bone composition using an X-ray microprobe. MATERIALS AND METHODS: The research was conducted on white rats of the Wistar strain. The fertilized females were divided into two groups: an Experimental Group (Group E) and a Control Group (Group C). The females in Group E were given caffeine orally (at 45 °C) in 30 mg/day doses from the 8th to the 21st day of pregnancy. The females in Group C were given water at the same temperature. The fetuses were used to assess the growth and mineralization of the skeleton. A qualitative analysis of the morphology and mineralization of bones was conducted using the alcian-alizarin method. For calcium and potassium analysis, an X-ray microprobe was used. RESULTS: By staining the skeleton using the alcian-alizarin method, changes in 52 of Group E fetuses were observed. The frequency of the development variants in the Group E rats was statistically higher, compared with Group C. CONCLUSIONS: Receiving caffeine at a higher temperature may result in different pharmacodynamics and significantly change tolerance to it. In Group E, a significant decrease in the calcium level, as well as an increase in the potassium level, was observed. The X-ray microprobe can be a perfect complement to the methods which enable determination of the mineralization of osseous tissue.

The influence of lead on the biomechanical properties of bone tissue in rats.

INTRODUCTION AND OBJECTIVE: Environmental lead (Pb) is a serious public health problem. At high levels, Pb is devastating to almost all organs. On the other hand, it is difficult to determine a safe level of exposure to Pb. More than 90% of the Pb in the adult human body and 70% in a child's body is stored in the bones. In the presented study, the effects of lead exposure on bones were studied for rats treated orally with Pb acetate in drinking water for 14 days. The hypothesis was tested that lead exposure negatively affects bone structure. MATERIALS AND METHODS: Femur strength was measured in a three-point bending test, whereas infrared spectroscopy (FTIR) was used to measure molecular structural changes. RESULTS: Lead significantly decreased the ratio of area of two types of vibrational transitions, which are highly specific to mineral to matrix ratio. The results of the biomechanical study show that femurs of rats treated by Pb-acetate appeared to be weaker than bones of the control group, and may produce a condition for the development of higher risk of fractures. Additionally, a great difference in body mass was observed between control and the Pb acetate-treated groups. CONCLUSIONS: The lower bone mineral content and the weaker mechanical properties of bones from Pb-treated rats are associated with the pathologic state dependent of the exposure of lead.

Fatty foci within the heart diagnosed with ECG-gated multi-slice computed tomography: frequency and morphology.

BACKGROUND: The purpose of our study was to analyze the frequency of focal fatty replacement (FR) of the heart, as well as the distribution and detailed morphology of FR in a large group of patients referred to multi-slice computed tomography with ECG-gating examinations (ECG-MSCT) for various clinical reasons. MATERIAL AND METHODS: The ECG-MSCT examinations of 1830 consecutive patients were analyzed. The examinations were performed using 8-row (1015 patients) and 64-row (815 patients) MSCT, in pre- and post-contrast scanning. We analyzed the morphology of FR, the dimensions and densities of changes, as well as the morphology and localization of FR with regard to clinical diagnosis. RESULTS: 204 subjects (11.1%) had FR within the heart (113 men; 91 women; mean age 57.8 years); 66% of fatty foci were seen only in the native scanning. The distribution of the fat was: right ventricle (RV) 31.9%, left ventricle (LV) 21.5%, biventricular 39.7%, interventricular or atrial septum 5.9%, and atria 1%. In the RV, fat was localized mainly in the papillary muscles, while in the LV fat was mainly subendocardial (p<0.001). The morphology of the fat was: linear 61.6%, oval 14.8%, punctuate 10.6%, irregular 10.2%, and bilobular 2.8%. Fat was primarily located subendocardially in the LV in patients after myocardial infarction. In patients with suspected coronary artery disease, it was mainly observed subpericardially in the RV and in papillary muscles (p<0.001). CONCLUSIONS: The incidental frequency of FR within the heart in patients diagnosed with the ECG-MSCT examinations is about 11%. Pre-contrast scanning is the most valuable for FR assessment.

Biomechanical parameters of the BP-enriched bone cement.

Bisphosphonates (BPs) are well-known substances with very efficient antiresorptive properties. Their beneficial actions are useful not only in achieving better bone mineral density but also in improving bone microarchitecture, strength and, consequently, its quality. Surgical cement, being a polymer composite, is required to be highly biocompatible and biotolerant. The goal of the presented study was to assess whether the enrichment of cement with pamidronate has changed its biomechanical properties. We compared the biomechanical parameters of clean bone cement and BP-enriched bone cement, which were both used formerly in our rat models. Biomechanical properties of BP-enriched bone cement are defined by two basic terms: stress and strain, which are caused by the influence of external force. In the investigatory process of the bone's biomechanical parameters, the compressive test and the three-point flexural tests were used. During the three-point flexural investigation, the sample was supported at both ends and loaded in the middle, resulting in a flexure. After a specific range of flexure, the sample was fractured. In obtained results, there were no significant differences in the values of the stress determined at the point of maximal load and the energy stored in the samples for proportional stress-strain limit (elastic region). There were also no significant differences in the density of the samples. The study shows that the enrichment of bisphosphonates causes yielding of the bone cement material. In the presented data, we conclude that use of pamidronate implanted in bone cement did not have a detrimental effect on its biomechanical properties. Therefore, the obtained results encouraged us to perform further in vivo experiments which assess the biomechanical properties of bones implanted with BP-enriched bone cement.

The effect of height and BMI on computer dynamic posturography parameters in women.

The human body's posture control is a complex system of organs and mechanisms which controls the body's centre of gravity (COG) over its base of support (BOS). Computerised Dynamic Posturography (CDP) allows for the quantitative and objective assessment of the sensory and motor components of the body's posture control system as well as of the integration and adaptation mechanisms in the central nervous system. The aim of this study was to assess the relationships between the body's height and BMI on CDP results in a group of young healthy women without any clinical symptoms of balance disorders. It was found that the MS depended significantly on the height and BMI of the subjects as well as on the SOT conditions. As the height and BMI increased the MS value decreased. The postural response latency (LC) in the MCT statistically significantly depended only on height and showed a positive correlation. The postural response latency increased with height. The postural response amplitude for both right and left lower limbs significantly depended on height and BMI, but only for the backward movement of the platform. The response amplitude for all platform translations under all MCT conditions increased with height and BMI. The body's resultant imbalance caused by the platform perturbations in the ADT was greater in shorter people and those with a lower BMI.

Modeling gender effects on electrical activity of single ventricular myocytes.

In this study we investigate the mechanisms underlying gender differences in the generation of arrhythmias in the long QT and Brugada syndromes. Simulations were conducted at the single myocyte level using a detailed mathematical model of human ventricular myocytes. Given the scarce human data on the gender-related differences in single cardiac cells, we assumed gender-related differences in five ionic-current systems: fast sodium current (INa), slowly inactivating late sodium current (INal), transient outward potassium current (Ito), slow delayed rectifier potassium current (IKs), and calcium current through the L-type channel (ICa(L)), based on experimental results obtained in canine myocytes. Our modeling results suggest that in left ventricular myocytes, enhanced INal under conditions of reduced repolarization reserve results in sex-dependent development of early afterdepolarizations (EADs) in the post-pause action potentials (APs). Moreover, this modeling study demonstrates increased propensity for the development of the loss of the AP dome in male epicardial myocytes of the right ventricle compared with other types of myocytes from the left and right ventricles. Finally, we also found a slight effect of INal on gender-dependent loss of AP dome in epicardial right ventricular myocytes. In conclusion, at the cellular level, gender differences in the development of EADs and the propensity to develop the loss of the AP dome can be attributed to male/female related differences in INa, INal, Ito, IKs, and ICa(L).

Use of X-ray microprobe to diagnose bone tissue demineralization after caffeine administration.

Caffeine is a methylxanthine which permeates the placenta. In studies on animals, it has been shown to produce teratogenic and embryotoxic effects in large doses. The objective of this study was to assess the influence of caffeine on the development of bone tissue, with particular reference to elemental bone composition using an X-ray microprobe. The research was conducted on rats. The fertilized females were randomly divided into an experimental and a control group. The experimental group was given caffeine orally in 30 mg/day doses from the 8th to the 21st day of pregnancy, while the control group was given water. The fetuses were used to assess the growth and mineralization of the skeleton. On the basis of double dyeing, a qualitative analysis of the bone morphology and mineralization was conducted. For calcium and potassium analysis, an X-ray microprobe was used. In 67 fetuses from the experimental group, changes in skeleton staining with the alcian-alizarin method were noticed. The frequency of the development of variants in the experimental group was statistically higher. In the experimental group,a significant decrease in the calcium level, as well as an increase in the potassium level, was observed. The X-ray microprobe's undoubted advantage is that is offers a quick qualitative and quantitative analysis of the elemental composition of the examined samples. Employing this new technique may furnish us with new capabilities when investigating the essence of the pathology process.

Lipomatous hypertrophy of the interatrial septum in ECG-gated multislice computed tomography of the heart.

BACKGROUND: Lipomatous hypertrophy of the interatrial septum (LHIS) is a benign disorder characterized by fat accumulation in the interatrial septum (IAS). The purpose of the study was to analyze the incidental detection of LHIS in patients with various clinical conditions, referred to ECG-gated multislice computed tomography (ECG-MSCT) examinations of the heart. MATERIAL/METHODS: The ECG-MSCT examinations of 5786 patients (2839 women; 2947 men), were analyzed. The examinations were performed using 8-row (1015 patients) and 64-row (4771 patients) MSCT, in pre- and postcontrast scanning. We analyzed the shape of the IAS, density and maximal thickness of IAS, the thickness of the epicardial adipose tissue, and the degree of contact of IAS with the ascending aorta and superior vena cava. We also determined body mass index (BMI) in patients with LHIS. RESULTS: LHIS was detected in 56 (0.96%) patients, with an average age of 61.5±9.8 years. The mean BMI in the analyzed group was 30.1±4.86. During the end-diastolic phase the thickness of IAS was significantly higher (p<0.0001), and on average equaled 18.3 mm. The mean optical density of the IAS was conspicuously higher (p<0.0001) in post-contrast phase than in pre-contrast phase. The thickness of the epicardial adipose tissue in the region of the left atrioventricular groove was on average 15 mm. In all cases the dumbbell shape of IAS was observed. CONCLUSIONS: The incidental frequency of LHIS occurrence in patients diagnosed with the ECG-MSCT examinations is about 1%. In most subjects it is linked with a higher BMI and increased thickness of the epicardial adipose tissue.

The mechanical and histological estimation of calcaneal tendon callus in rats after PRP injection.

BACKGROUND: The study investigated the potential impact of platelet-rich plasma on tendon healing. MATERIAL/METHODS: The study was conducted in 88 young, sexually mature rats, Wistar strain. The animals were randomly divided into two groups. The animals from the examined group (n=44) with an operated calcaneal tendon were given subcutaneously allogeneic PRP. The animals from the control group (n=44) were given 0.9% NaCl solution within the area of calcaneal tendon damage. After 7, 14, 21, and 42 days, the tendons were tested mechanically using the universal testing machines (UTM, Lloyd LRX), and were subjected to histological evaluation. RESULTS: The study evaluated the maximum breaking force (Fmax), the force at the end of the proportional range (Fs) and stiffness of the tendons (H). After 7 days of the experiment, there were significant differences in H (P=0.021), between the examined and control groups. There were no significant differences in Fmax (P=0.53) and Fs (P=0.48) after 7 days. Mean values of Fmax, Fs and H after 14, 21, and 42 days in the study group were significantly higher compared to the control group (P<0.05). In the histological evaluation, the tendons of the examined groups were characterized by higher cellular and vascular density and a more orderly arrangement of collagen fibers compared to the control groups. CONCLUSIONS: Growth factors in allogeneic PRP increased the mechanical strength of regenerating calcaneal tendons after 14, 21, and 42 days from injury. PRP resulted in the increased histological maturity of the tendon callus in examined groups, at each stage of the experiment.

The influence of caffeine on the biomechanical properties of bone tissue during pregnancy in a population of rats.

The influence of pregnancy on bone tissue metabolism is not completely understood. Caffeine also has a potentially negative influence on bones. The aim of this study was the evaluation of changes in the bones of pregnant rats under the influence of caffeine. The experiment was carried out on Wistar rats. The evaluation of rats' bone tissue quality was performed based on bone density measurements and resistance examinations. It analyzed the impact of caffeine on the degree of bone tissue mineralization and the composition of the bones. The mean value of pelvises 'wet' and 'dry' densities in a group of pregnant rats with caffeine intake was lower compared to the control group. The deformation in maximal load point of the femur shaft in the experimental group was significantly higher than in the control group. In the experimental group, the percentage of water in the bones was significantly higher, while the content of inorganic phase was significantly lower compared to the control group. The changes of biomechanical parameters in the group of pregnant rats with caffeine intake indicate its negative influence on the bone. Our results show higher plasticization of the bone shafts of the animals under the influence of caffeine. Higher deformation of bone shafts may have an effect on the statics of the skeleton. The administration of caffeine significantly affected the quantitative composition of the bone.

The evaluation of mechanical properties of animal tendons after corticosteroid therapy.

The purpose of the study was to examine the effect of systemic glucocorticosteroids administration on mechanical properties of animal tendons. Twenty female Wistar rats were divided into two groups and those that formed experimental group were subjected activity of hydrocortisone given to the peritoneum. Mechanical tests were performed. Hydrocortisone administration caused reduction of force value and the increase of strain, also the value of elasticity module was significantly smaller comparing to the control group. The results of biomechanical tests suggested that glucocorticoids produce less stiffness tendon, which fails in maximum point of load. This study revealed that systemic hydrocortisone administration changes significantly mechanical properties of tendons, which may cause frequent failure of the tendon.