Saccharomyces cerevisiae

Intricate, dynamic, and absolutely unavoidable ageing affects cells and organisms through their entire lifetime. Driven by diverse mechanisms all leading to compromised cellular functions and finally to death, this process is a challenge for researchers. The molecular mechanisms, the general rules that it follows, and the complex interplay at a molecular and cellular level are yet little understood. Here, we present our results showing a connection between the linker histones, the higher-order chromatin structures, and the process of chronological lifespan of yeast cells. By deleting the gene for the linker histone in Saccharomyces cerevisiae we have created a model for studying the role of chromatin structures mainly at its most elusive and so far barely understood higher-order levels of compaction in the processes of yeast chronological lifespan. The mutant cells demonstrated controversial features showing slower growth than the wild type combined with better survival during the whole process. The analysis of the global chromatin organization during different time points demonstrated certain loss of the upper levels of chromatin compaction in the cells without linker histone. The results underlay the importance of this histone for the maintenance of the chromatin loop structures during ageing

Antioxidative defence mechanism contributes to desiccation tolerance in Haberlea rhodopensis population naturally exposed to high irradiation

Drought induced stress is one of the most important among the environmental challenges. Haberlea rhodopensis, a chlorophyll-retaining resurrection plant, can survive desiccation to air-dry stage in its usual low irradiance habitat (“shade” plants). Nevertheless, in the past years, some populations living under high irradiance (“sun” plants) have been also discovered with the same ability to survive dehydration. In order to clarify the adaptation mechanisms to a high irradiation habitat, superoxide dismutase (SOD) activity determined by activity staining on polyacrylamide gels and malondialdehyde (MDA) content of sun and shade plants collected from high and low irradiance environment, respectively, were studied. Desiccation induced a significantly higher induction in SOD activity and thus a smaller increase in the MDA content in sun compared to shade plants. The MDA content and SOD activity was restored in both sun and shade plants after six-day rehydration. Nevertheless, the SOD activity remained higher in rehydrated sun leaves compared to the well-hydrated initial stage. The early enhancement of SOD activity in dehydrating sun plants contributes to the higher stress tolerance of these populations

Pulmonary perfusion scintigraphy in lung carcinoma and lobectomy

PURPOSE: Most successful treatment of the lung cancer patients is the surgical resection. Lung perfusion scintigraphy is established method in the complex pre-operative diagnostics of lung carcinoma. It is used for selection of candidates for surgical treatment and in determination of operability and in decision on the operation volume.MATERIALS AND METHODS: We analyzed retrospectively the value of lung perfusion scintigraphy in 27 cases with primary lung carcinoma who had a lobectomy. Survival probability was calculated by Kaplan- Meier method. The log rank test was used to compare survival rates between groups.RESULTS: All patients with lobectomy were staged pre-operatively by noninvasive procedures at stages I-IIIA. The lung perfusion scintigraphy demonstrated an enlarged mediastinum at 1 of the patients. Impaired perfusion in homolateral hilum and in the contralateral hilum was found in some of the patients. Changes in affected lung perfusion varied from impaired in different rate to perfusion defect. Perfusion indices at affected lung have mean=48,59%. The survival of patients with Perfusion index less than 49% was mean = 56,333 months, and median = 35 months (3 years). The survival of patients with Perfusion index more than 49% was mean = 99,214 months, and median = 64 months (5.3 years). For I and II stage mean survival time was 120,727 months, and median survival time was 112 months (9.3 years). For IIIA and IIIB stage mean survival time was 48,667 months, and median survival time was 29 months (2,4 years).CONCLUSION: Lung perfusion scintigraphy is a valuable method in pre-operative diagnosis of lung carcinoma in determination of the extent of perfusion impairment in the affected lung and for determination of functional operability. Lobectomy is possible when perfusion in affected lung is over 41%, but the lower perfusion is not surely a contraindication for lobectomy. The extent of perfusion impairment is proportional to survival rate. Patients with lower perfusion impairments have more than 5 years median survival. In postoperative period perfusion scintigraphy shows re-distribution of perfusion in the healthy lung and in the rest of the operated lung. The survival of patients with lobectomy is corresponding to the clinical stage statistically significant

Value of lung perfusion scintigraphy in predicting unresectability of patients with lung cancer and explorative thoracotomy

Purpose: To determine the value of lung perfusion on predicting unresectability of lung carcinoma in patients with exploratory thoracotomy.Materials and methods: We analyzed retrospectively the value of lung perfusion scintigraphy in 25 cases with primary lung carcinoma who had an exploratory thoracotomy (18 right and 7 left thoracotomy), regarding preoperative suggestion of unresectability. In most of these patients other noninvasive diagnostic methods (X-ray and CT) did not indicate inoperability.Results: Only the perfusion lung scintigraphy demonstrated defects near the ipsilateral hilum and/or an enlargement of the mediastinum, displacement of mediastinum, displacement (pulling) of the hilum of the affected lung or a part of it to the mediastinum. At thoracotomy we found an involvement of hilar vessels and the mediastinum by the tumor or by `bulky` nodal metastases. Common peripheral concentric decrease of affected lung perfusion image dimensions, lacking or negligible perfusion of the affected lung also suggest inoperability. Perfusion indices at localization of the tumor in the right lung (15 of the patients) were mean=40,8%, SD=11,02%, SE=2,7%, and at localization in the left lung (6 of the patients) mean=36,27%, SD=10,60%, SE=4,01%.Conclusion: These findings show that in some patients with bronchial carcinoma the perfusion scintigraphy image can suggest a potential unresectability and requires a more extensive staging like mediastinoscopy or thoracoscopy