Effects of clary sage oil and its main components, linalool and linalyl acetate, on the plasma membrane of Candida albicans: an in vivo EPR study.

The effects of clary sage (Salvia sclarea L.) oil (CS-oil), and its two main components, linalool (Lol) and linalyl acetate (LA), on cells of the eukaryotic human pathogen yeast Candida albicans were studied. Dynamic and thermodynamic properties of the plasma membrane were investigated by electron paramagnetic resonance (EPR) spectroscopy, with 5-doxylstearic acid (5-SASL) and 16-SASL as spin labels. The monitoring of the head group regions with 5-SASL revealed break-point frequency decrease in a temperature dependent manner of the plasma membrane between 9.55 and 13.15 °C in untreated, in CS-oil-, Lol- and LA-treated membranes. The results suggest a significant increase in fluidity of the treated plasma membranes close to the head groups. Comparison of the results observed with the two spin labels demonstrated that CS-oil and LA induced an increased level of fluidization at both depths of the plasma membrane. Whereas Lol treatment induced a less (1 %) ordered bilayer organization in the superficial regions and an increased (10 %) order of the membrane leaflet in deeper layers. Acute toxicity tests and EPR results indicated that both the apoptotic and the effects exerted on the plasma membrane fluidity depended on the composition and chemical structure of the examined materials. In comparison with the control, treatment with CS-oil, Lol or LA induced 13.0, 12.3 and 26.4 % loss respectively, of the metabolites absorbing at 260 nm, as a biological consequence of the plasma membrane fluidizing effects. Our results confirmed that clary sage oil causes plasma membrane perturbations which leads to cell apoptosis process.

Analysis of Research Activity in Gastroenterology: Pancreatitis Is in Real Danger.

OBJECTIVE: Biomedical investment trends in 2015 show a huge decrease of investment in gastroenterology. Since academic research usually provides the basis for industrial research and development (R&D), our aim was to understand research trends in the field of gastroenterology over the last 50 years and identify the most endangered areas. METHODS: We searched for PubMed hits for gastrointestinal (GI) diseases for the 1965-2015 period. Overall, 1,554,325 articles were analyzed. Since pancreatology was identified as the most endangered field of research within gastroenterology, we carried out a detailed evaluation of research activity in pancreatology. RESULTS: In 1965, among the major benign GI disorders, 51.9% of the research was performed on hepatitis, 25.7% on pancreatitis, 21.7% on upper GI diseases and only 0.7% on the lower GI disorders. Half a century later, in 2015, research on hepatitis and upper GI diseases had not changed significantly; however, studies on pancreatitis had dropped to 10.7%, while work on the lower GI disorders had risen to 23.4%. With regard to the malignant disorders (including liver, gastric, colon, pancreatic and oesophageal cancer), no such large-scale changes were observed in the last 50 years. Detailed analyses revealed that besides the drop in research activity in pancreatitis, there are serious problems with the quality of the studies as well. Only 6.8% of clinical trials on pancreatitis were registered and only 5.5% of these registered trials were multicentre and multinational (more than five centres and nations), i.e., the kind that provides the highest level of impact and evidence level. CONCLUSIONS: There has been a clear drop in research activity in pancreatitis. New international networks and far more academic R&D activities should be established in order to find the first therapy specifically for acute pancreatitis.

Structural background for serological cross-reactivity between bacteria of different enterobacterial serotypes.

The structure of the oligosaccharide repeating units of endotoxins from Gram-negative bacteria is characteristic for the different serogroups and serotypes of bacteria. Detailed examination of the cross-reactions of three enterobacterial serotypes, Proteus morganii O34, Escherichia coli O111, and Salmonella enterica sv. Adelaide O35, was performed using sensitive tests (ELISA, immunoblotting). Fine differences between the endotoxins of the bacteria were detected using silver staining of SDS-PAGE gels and chip-technology for the intact lipopolysaccharides (LPSs). The compositions of the O-specific polysaccharides of LPSs extracted from the bacteria were studied, and it was proven that the three cross-reacting bacteria contain O-antigens built from the same monosaccharides, namely colitoses linked to glucose, galactose, and N-acetyl-galactosamine. The NMR and GC-MS studies revealed that the most probable component for the cross-reaction is the rare sugar, colitose.

Regulation of the unbalanced redox state in a Schizosaccharomyces pombe tert-butyl hydroperoxide-resistant mutant.

The one-gene mutation in the tert-butyl hydroperoxide-resistant mutant hyd1-190 of the fission yeast Schizosaccharomyces pombe led to a 4-fold increase in resistance to t-BuOOH and decreased specific concentrations of superoxide and total thiols in comparison with the parental strain hyd+. It suggested an unbalanced redox state of the cells, which induced continuously increased specific activities of glutathione peroxidase, glutathione reductase and glutathione S-transferase and decreased activities of the antioxidant enzymes superoxide dismutases and glucose-6-phosphate dehydrogenase to regulate the redox balance of the mutation-induced permanent, low-level but tolerable internal stress. These results may contribute to the understanding of internal, oxidative stress-related human diseases.

Citrinin-induced fluidization of the plasma membrane of the fission yeast Schizosaccharomyces pombe.

Citrinin (CTN) is a toxic fungal metabolite that is a hazardous contaminant of foods and feeds. In the present study, its acute toxicity and effects on the plasma membrane of Schizosaccharomyces pombe were investigated. The minimum inhibitory concentration of CTN against the yeast cells proved to be 500 µM. Treatment with 0, 250, 500 or 1000 µM CTN for 60 min resulted in a 0%, 2%, 21% or 100% decrease, respectively, in the survival rate of the cell population. Treatment of cells with 0, 100, 500 or 1000 µM CTN for 20 min induced decrease in the phase-transition temperature of the 5-doxylstearic acid-labeled plasma membrane to 16.51, 16.04, 14.18 or 13.98°C, respectively as measured by electron paramagnetic resonance spectroscopy. This perturbation was accompanied by the efflux of essential K⁺ from the cells. The existence of an interaction between CTN and glutathione was detected for the first time by spectrofluorometry. Our observations may suggest a direct interaction of CTN with the free sulfhydryl groups of the integral proteins of the plasma membrane, leading to dose-dependent membrane fluidization. The change in fluidity disturbed the ionic homeostasis, contributing to the death of the cells, which is a novel aspect of CTN cytotoxicity.

Chromate tolerance caused by reduced hydroxyl radical production and decreased glutathione reductase activity in Schizosaccharomyces pombe.

The stable Cr(VI)-tolerant chr1-66T mutant of Schizosaccharomyces pombe, which carries one simple gene mutation responsible for Cr(VI) tolerance, accumulated and reduced the chromate anion (CrO(4)(2-)) significantly more slowly than did its parental strain 6chr(+). The mutant chr1-66T proved to be sensitive to oxidative stressors such as H(2)O(2), menadione, tert-butyl hydroperoxide and Cd(2+). Both the Cr(VI) tolerance and the oxidative stress sensitivity were attributed to a decreased specific glutathione reductase activity. These effects were also enhanced with a decrease in the specific mitochondrial Mn-SOD activity.