Hsp70 promotes epithelial sodium channel functional expression by increasing its association with coat complex II and its exit from endoplasmic reticulum

The epithelial sodium channel (ENaC) plays an important role in the homeostasis of blood pressure and of the airway surface liquid, and inappropriate regulation of ENaC results in refractory hypertension (in Liddle syndrome) and impaired mucociliary clearance (in cystic fibrosis). The regulation of ENaC by molecular chaperones, such as the 70-kDa heat shock protein Hsp70, is not completely understood. Building on the previous suggestion by our group that Hsp70 promotes ENaC functional and surface expression in Xenopus oocytes, we investigated the mechanism by which Hsp70 acts upon ENaC in epithelial cells. In Madin-Darby canine kidney cells stably expressing epitope-tagged αβγ-ENaC and with tetracycline-inducible overexpression of Hsp70, treatment with 1 or 2 μg/ml doxycycline increased total Hsp70 expression ~2-fold and ENaC functional expression ~1.4-fold. This increase in ENaC functional expression corresponded to an increase in ENaC expression at the apical surface of the cells and was not present when an ATPase-deficient Hsp70 was similarly overexpressed. The increase in functional expression was not due to a change in the rate at which ENaC was retrieved from the apical membrane. Instead, Hsp70 overexpression increased the association of ENaC with the Sec24D cargo recognition component of coat complex II, which carries protein cargo from the endoplasmic reticulum to the Golgi. These data support the hypothesis that Hsp70 promotes ENaC biogenesis and trafficking to the apical surface of epithelial cells.     

Effectiveness of CSE to counterstain particles and dead bacterial cells with permeabilised membranes: application to viability assessment in waters

The CSE dye (Chemunex, Maisons-Alfort, France) was combined with an activity marker to improve bacterial activity assessment in natural waters. Its effectiveness to counterstain dead cells with permeabilised membranes was investigated on live and dead cells of a variety of strains from collections or isolated from the natural environment. Cells were killed by heat treatment. For all strains tested, the fluorescent dye showed an intense staining of killed cells having permeabilised membranes while no significant signal was detected when applied to live cells. Furthermore, the CSE dye had no toxicity on viable cells. Then, CSE was combined with the ChemChrome V6 dye (Chemunex) to assess the activity of bacterial cells in different waters. Both fluorescences were analysed simultaneously by solid-phase cytometry. The active cell counts were sometimes lower when both dyes were combined suggesting that CSE was able to counterstain cells having a residual esterase activity and compromised membranes. These cells were subtracted from the active cell counts determined with ChemChrome V6. In most samples, active cell counts were congruent with those determined by the direct viable count method.     

Is p53 intronic variant G13964C associated with predisposition to cancer?

Germline mutations of the p53 gene confer a high risk of diverse malignancies. The highest frequency of inherited p53 defects was noted in Li-Fraumeni syndrome (LFS), but almost half of the mutations were found in families with incomplete Li-Fraumeni-like syndrome (LFL), including familial breast cancer cases. Recently, a germline intronic G13964C base change of the p53 was reported as a high-risk mutation associated with familial breast cancer (LEHMAN et al. 2000). We genotyped Polish cancer patients and healthy control individuals for the G13964C variant. Patients were chosen from cancer families with phenotypes typical for germline mutations of p53 (LFS, LFL), BRCA1 [hereditary breast (ovarian) cancer, HB(O)C] or a complex consistent with both LFL and HB(O)C. Children with leukemia were included in the study as another high risk group (FELIX et al. 1992). The G13964C variant was detected in six of 87 (6.9%) cancer patients (including two ALL children), but also in eight of 96 (8.3%) control individuals (p > 0.4). Thus we found no evidence of the variant's association with a high risk of cancer.     

The role of the spectral domain ocular coherence tomography in detection of age-related macular degeneration

Age-related macular degeneration (ARMD) is one of the most common causes of the vision loss and blindness in developed countries. Among other harmful effects, exposure to the UV radiation is the most prominent factor for the development of the disorder. Using the method of SD OCT (Spectral Domain Ocular Coherence Tomography) we performed measurement of the neurosensory retinal thickness of 19 eyes of low vision patients from the population of Primorsko-Goranska County of Republic of Croatia, with dry form of the terminal macular degeneration. These results we compared with control measurements performed on 28 eyes of healthy, normal vision subjects from same County. We determined following parameters: central foveal thickness (CFT), macular volume (MV) and mean foveal thickness (MFT) in the both groups. Results showed statistically significant reduction of CFT in the group of normal vision female patients when compared to males, while any significant difference of CFT between total groups of normal vision individuals and low vision patients was not detected. Furthermore, we noticed statistically significant (p < 0.000001) decrease of the MV in the group of the low vision patients in comparison to healthy subjects and statistically significant (p < 0.000001) reduction of the MFT of the low vision patients when compared to normal vision individuals. In our study we detected the absence of any significant difference of the CFT between healthy and low vision population, what looks like controversial finding, because neurosensory retina in the ARMD is thin and atrophic, but on the other side it is known that fixation point in low vision patients is translocated from the damaged fovea to extrafoveal region, usually above the fovea, where neurosensory retina is of the normal thickness, but with the less sensitivity. Furthermore, our results suggest possible connection of higher incidence of ARMD with lower CFT in females. Owing to the thicker neurosensory retina in males and better protection, damaging effect of the UV irradiation, which is the proven factor of ARMD development, is smaller. From the evolutionary point of view it is possible that males in all vertebrates have more resistant macula because during the evolutionary process they have spent much more time outside in the sunlight than females.     

West syndrome with periventricular leukomalacia: ten-year clinical study

The aim of the study was to evaluate magnetic resonance imaging (MRI) findings in infants with periventricular leukomalacia (PVL) and West syndrome (WS) and determine the neurodevelopmental outcome in children with West syndrome and PVL. Ultrasound and brain MRI were performed in 37 infants with recognized PVL. PVL was categorized according to De Vries, whereas West syndrome was categorized according to International League Against Epilepsy 1989. West syndrome in our patients developed during the first 2 years of life. The most common interictal abnormality was hypsarrhythmia. All, except two patients had delayed development and various degrees of mental retardation. The most characteristic neuroimaging findings were major reduction in cerebral cortical gray matter volume, reduction in the volume of brain myelin, and delayed myelination. These findings may explain the anatomical association between the West syndrome onset and PVL and intellectual and cognitive deficit in premature infants with PVL.