Peroxiredoxins in plants and cyanobacteria

Peroxiredoxins (Prx) are central elements of the antioxidant defense system and the dithiol-disulfide redox regulatory network of the plant and cyanobacterial cell. They employ a thiol-based catalytic mechanism to reduce H2O2, alkylhydroperoxide, and peroxinitrite. In plants and cyanobacteria, there exist 2-CysPrx, 1-CysPrx, PrxQ, and type II Prx. Higher plants typically contain at least one plastid 2-CysPrx, one nucleo-cytoplasmic 1-CysPrx, one chloroplast PrxQ, and one each of cytosolic, mitochondrial, and plastidic type II Prx. Cyanobacteria express variable sets of three or more Prxs. The catalytic cycle consists of three steps: (i) peroxidative reduction, (ii) resolving step, and (iii) regeneration using diverse electron donors such as thioredoxins, glutaredoxins, cyclophilins, glutathione, and ascorbic acid. Prx proteins undergo major conformational changes in dependence of their redox state. Thus, they not only modulate cellular reactive oxygen species- and reactive nitrogen species-dependent signaling, but depending on the Prx type they sense the redox state, transmit redox information to binding partners, and function as chaperone. They serve in context of photosynthesis and respiration, but also in metabolism and development of all tissues, for example, in nodules as well as during seed and fruit development. The article surveys the current literature and attempts a mostly comprehensive coverage of present day knowledge and concepts on Prx mechanism, regulation, and function and thus on the whole Prx systems in plants.     

Quality of life,compliance, sleep and nasopharyngeal side effects during CPAP therapy with and without controlled heated humidification

Purpose  

To determine the effect of a controlled heated breathing tube humidifier (cHH) on the quality of life (QOL), compliance and nasopharyngeal side effects during continuous positive airway pressure (CPAP) therapy in patients with obstructive sleep apnea syndrome (OSAS) in comparison with conventional CPAP.     

Regional impairment of 18F-FDG uptake in the cervical spinal cord in patients with monosegmental chronic cervical myelopathy

Objective  

The aim of this preliminary report was to assess glucose metabolism in the cervical spine of patients with chronic compressive myelopathy by using FDG PET.     

O-(2-[18F]fluoroethyl)-L-tyrosine: uptake mechanisms and clinical applications

O-(2-[18F]fluoroethyl)-L-tyrosine (FET) is a promising tracer for PET that has demonstrated convincing results especially in the diagnostics of brain tumors. In contrast to other radiolabeled amino acids, it can be produced with high efficiency and distributed in a satellite concept like the widely used 2-[18F]fluoro-2-deoxy-D-glucose. Although FET is not incorporated into proteins, it shows high uptake in cerebral gliomas and in extracranial squamous cell carcinomas owing to increased transport. The tracer exhibits high in vivo stability, low uptake in inflammatory tissue and suitable uptake kinetics for clinical imaging, which indicates that it may become a new standard tracer for PET. In this article, the present knowledge on the uptake mechanisms and the clinical applications of FET are reviewed and the clinical perspectives are discussed.     

Die wirkung der salicylsäure auf die proliferationskinetik psoriatischer epidermiszellen

Zusammenfassung Salicylsäure in therapeutischer Dosierung von 0,5 bis 10% ist offenbar ohne Einfluß auf die Proliferationskinetik psoriatischer Epidermiszellen.Mit Hilfe autoradiographischerin vitro-Verfahren, bei 6 Patienten H3-Thymidin-Markierung, bei 12 Patienten Doppelmarkierung mit C14- und H3-Thymidin, wurden teils der H3-Thymidin-Markierungsindex (H3-I), teils H3-I, DNS-Synthesezeit (ts) und Generationszeit (tc) bestimmt. Dabei fanden sich bei einwöchiger äußerlicher Anwendung von Salicylsäure in weißer Vaseline in Konzentrationen von 0,5, 2 und 10% keine signifikanten Veränderungen.

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The effect of salicylic acid on epidermal cell proliferation kinetics in psoriasis

Summary Salicylic acid in the therapeutic concentrations from 0.5 to 10% does not affect the rate of proliferation of psoriatic epidermal cells.In 18 patients suffering from psoriasis the H 3-I (H3-thymidine labelling index) was determined using autoradiographicin vitro labelling techniques.In 12 of these patients double-labelling with C14- and H3-thymidine was used to determine the H3-I, the DNA-synthesis time (ts) and the duration of the cell-cycle (tc). No significant changes were observed following external application of salicyclic acid in white Vaseline in concentrations of 0.5, 2 and 10% for one week.

     

Comparison of F-FET and F-FDG PET in brain tumors

The purpose of this study was to compare the diagnostic value of positron emission tomography (PET) using [¹⁸F]-fluorodeoxyglucose (¹⁸F-FDG) and O-(2-[¹⁸F]fluoroethyl)-l-tyrosine (¹⁸F-FET) in patients with brain lesions suspicious of cerebral gliomas.

Methods

Fifty-two patients with suspicion of cerebral glioma were included in this study. From 30 to 50 min after injection of 180 MBq ¹⁸F-FET, a first PET scan (¹⁸F-FET scan) was performed. Thereafter, 240 MBq ¹⁸F-FDG was injected and a second PET scan was acquired from 30 to 60 min after the second injection (¹⁸F-FET/¹⁸F-FDG scan). The cerebral accumulation of ¹⁸F-FDG was calculated by decay corrected subtraction of the ¹⁸F-FET scan from the ¹⁸F-FET/¹⁸F-FDG scan. Tracer uptake was evaluated by visual scoring and by lesion-to-background (L/B) ratios. The imaging results were compared with the histological results and prognosis.

Results

Histology revealed 24 low-grade gliomas (LGG) of World Health Organization (WHO) Grade II and 19 high-grade gliomas (HGG) of WHO Grade III or IV, as well as nine others, mainly benign histologies. The gliomas showed increased ¹⁸F-FET uptake (>normal brain) in 86% and increased ¹⁸F-FDG uptake (>white matter) in 35%. ¹⁸F-FET PET provided diagnostically useful delineation of tumor extent while this was impractical with ¹⁸F-FDG due to high tracer uptake in the gray matter. A local maximum in the tumor area for biopsy guidance could be identified with ¹⁸F-FET in 76% and with ¹⁸F-FDG in 28%. The L/B ratios showed significant differences between LGG and HGG for both tracers but considerable overlap so that reliable preoperative grading was not possible. A significant correlation of tracer uptake with overall survival was found with ¹⁸F-FDG only. In some benign lesions like abscesses, increased uptake was observed for both tracers indicating a limited specificity of both techniques.

Conclusions

¹⁸F-FET PET is superior to ¹⁸F-FDG for biopsy guidance and treatment planning of cerebral gliomas. The uptake of ¹⁸F-FDG is associated with prognosis, but the predictive value is limited and a histological evaluation of tumor tissue remains necessary. Therefore, amino acids like ¹⁸F-FET are the preferred PET tracers for the clinical management of cerebral gliomas.