Evaluation of pure-tone audiometric protocols in vestibular schwannoma screening

The objective was to evaluate the pure-tone audiogram-based screening protocols in VS diagnostics. We retrospectively analyzed presenting symptoms, pure tone audiometry and MRI finding from 246 VS patients and 442 controls were collected to test screening protocols (AAO-HNS, AMCLASS-A/B, Charing Cross, Cueva, DOH, Nashville, Oxford, Rule3000, Schlauch, Seattle, Sunderland) for sensitivity and specificity. Results were pooled with data from five other studies, and analysis of sensitivity, specificity and positive likelihood ratio (LR+) for each protocol was performed. Our results show that protocols with significantly higher sensitivity (AMCLASS-A/B, Nashville) show also significantly lowest specificity, and tend to have low association (positive likelihood ratio, LR+) to the VS. The highest LR+ was found for protocols AAO-HNS, Rule3000 and Seattle. In conclusions, knowing their properties, screening protocols are simple decision-making tools in VS diagnostic. To use the advantage of the highest sensitivity, protocols AMCLASS-A + B or Nashville can be of choice. For more reasonable approach, applying the protocols with high LR+ (AAO-HNS, Rule3000, Seattle) may reduce the overall number of MRI scans at expense of only few primarily undiagnosed VS.     

Clinical determinants of primary and secondary fatigue in patients with Parkinson’s disease

Clinical and psychosocial factors associated separately with primary and secondary fatigue in Parkinson’s disease (PD) patients have not been thoroughly studied before. The aim of our study was to assess factors associated with different fatigue domains in groups with primary and secondary fatigue in PD separately. We divided 165 non-demented PD patients according to the absence/presence of depression, anxiety and excessive somnolence into groups with primary fatigue (N = 63) and with secondary fatigue (N = 102). Fatigue domains examined using the multidimensional fatigue inventory were associated through multiple linear regression analyses for each group separately with sociodemographic data, disease duration, functional status as assessed by the Unified Parkinson’s Disease Rating Scale, treatment, depression, anxiety, excessive somnolence and sleep quality. Out of the assessed non-motor symptoms, fatigue was the most frequent (77.6 %). The prevalence of fatigue in the secondary fatigue group was significantly higher than in the primary fatigue group. Both fatigue groups differed significantly in factors associated with different fatigue domains. Functional status or other disease-related factors were not associated with primary fatigue. In the secondary fatigue group, we found associations between some fatigue domains and functional status, older age, male gender and higher anxiety scores. To our knowledge, this is the first study to separately describe clinical determinants and psychosocial factors associated with different fatigue domains in primary and secondary fatigue in PD, underlining the importance of distinguishing primary and secondary fatigue in future PD studies and clinical practice.     

Effect of calcium ions on the gelling and drug release characteristics of xanthan matrix tablets

Xanthan is a well-known biopolymer. It is an anionic polysaccharide, whose primary structure depends on the bacterial strain and fermentation conditions. Xanthan was extensively studied in combination with galactomannans, and over 90 patents cover the technology of this preparation. Our aim was to investigate the relation between the physical properties of a xanthan matrix in the absence or presence of calcium ions and its influence on the release of pentoxifylline. The release of pentoxifylline from xanthan tablets in purified water was shown to be very slow and governed by the process of polymer relaxation. The presence of calcium ions significantly increased the drug release, changing the release mechanism into a more diffusion controlled one. Xanthan matrices showed substantially faster and more extensive swelling in water than in the presence of Ca2+ ions. Surprisingly, negative correlation between drug release and degree of swelling was obtained for xanthan: the higher the swelling, the slower the drug release. Higher ionic strength led to lower erosion of xanthan tablets, and the gel layers formed were more rigid and of firmer texture, as shown by rheological experiments and textural profiling. The results indicate that the presence of Ca2+ ions in the solution or in matrices does not cause crosslinking of xanthan polymers, but causes charge screening of ionized groups on the trisaccharide side chains of xanthan, leading to lower inter-molecular repulsion and changing water arrangement. The understanding of the parameters influencing drug release leads to the conclusion that xanthan is suitable for controlled release formulations, especially with the incorporation of certain small counterions.     

A rabbit used as a model for testing hematopoietic tissue transplants.

Allogenic transplantations of bone marrow or spleen cells were carried out on rabbits treated with cyclophosphamide. About 50% of the recipients developed chimerism of peripheral blood cells. Chimerism was a passing phenomenon prevailing from 14 to 180 days after grafting. A phenomenon indicating that not all cell lines develop after transplantation from the donor stem cells, was observed. This phenomenon has been called "restricted chimerism". The GvH reaction was of a chronic type. Relative spleen weights were significantly increased in animals receiving the spleen cell grafts, but not in animals receiving bone marrow grafts. A direct positive erythrocyte Coombs test was found in almost all graft recipients. In addition cytotoxic autoantibodies against lymphocytes were present in sera of about 20% of the recipients.     

Hypothesis of regulation of hip joint cartilage activity by mechanical loading

Hypothesis of regulation of proteosynthetic activity of chondrocytes is suggested. A deformation of the cartilage caused by contact hip joint stress and consequent deformation of the chondrocytes are considered as main factors that could influence the metabolism of the cartilage.     

Distribution and prognostic significance of cell cycle proteins in squamous carcinoma of the larynx,hypopharynx and adjacent epithelial hyperplastic lesions

Alterations of cell cycle proteins contribute to the development and biological behaviour of malignant tumours. We evaluated the distribution and prognostic significance of immunohistochemically detected proteins p53, p21, Rb, and cyclin D1 in 101 laryngeal and hypopharyngeal squamous cell carcinomas (SCC) and adjacent epithelial hyperplastic lesions (EHL). Protein expression was correlated with tumour grade and stage. Varying patterns of protein expression were found in SCC. A significant correlation (p<0.05) was found between Rb expression and tumour grade. Different grades of EHL exhibited randomly distributed p53 and cyclin D1 positive cell clusters with no association to the pattern of their expression in SCC. Our study demonstrated derailment of cell cycle regulation in almost all cases of SCC of the larynx and hypopharynx. However, only cyclin D1 expression had an independent prognostic value for cancer-specific survival. The results also suggest that Rb gene inactivation, although rare, might be more important in the development of SCC than previously thought.