Effects of high temperature and low pH on photosystem 2 photochemistry in spinach thylakoid membranes

The effects of temperature (25–45 °C) and pH (7.5–5.5) on photosystem (PS) 2 was studied in spinach (Spinacia oleracea L.) thylakoid membranes using chlorophyll a fluorescence induction kinetics. In high temperature and low pH treated thylakoid membranes a decline in the variable to maximum fluorescence ratio (F_v/F_m) and PS 2 electron transport rate were observed. More stacking in thylakoid membranes, studied by digitonin fractionation method, was observed at low pH, while the degree of unstacking increased under high temperature conditions. We conclude that the change in pH does not significantly affect the donor/acceptor side of PS 2 while high temperature does. Fluorescence emission spectra at 77 K indicated that low pH is associated with energy redistribution between the two photosystems while high temperature induced changes do not involve energy re-distribution. We suggest that both, high temperature and low pH, show an inhibitory effect on PS 2 but their mechanisms of action are different.     

Preliminary clinical outcomes of patients treated with vaginal brachytherapy alone using multi-channel vaginal brachytherapy applicator in operated early-stage endometrial cancer

BackgroundRecommendations for adjuvant treatment for postoperative, early-stage endometrial cancer varies from observation through vaginal brachytherapy alone to pelvic radiation. While observation alone can lead to recurrence, external radiotherapy has increased morbidity. The aim of this study is to show our results with vaginal brachytherapy alone using a multichannel applicator for treatment of early-stage endometrial cancer.Materials and methodsConsecutive patients undergoing vaginal brachytherapy alone following surgery for early-stage endometrial cancer were examined. A Miami multichannel vaginal brachytherapy applicator was used to deliver HDR brachytherapy in 62 patients from May 2013 to June 2018. CT scan-based images guided planning. A dose of 5.5–6.5 Gy × 4 fractions was prescribed 5 mm from the surface of the applicator.ResultsAt a median follow up of 19 months (6–48 months), 93% of patients treated were alive with no recurrence. Two patients had only local recurrence, and 1 was salvaged with external radiotherapy and chemotherapy. There was only one nodal failure and 2 distant failures. There was no grade 2 or higher vaginal, gastrointestinal or genitourinary toxicity.ConclusionVaginal brachytherapy alone using a multichannel applicator can be considered for early-stage endometrial cancers without compromising outcomes.     

Efficacy of Cryptdin-2 as an Adjunct to Antibiotics from Various Generations Against Salmonella

Emerging drug resistance in Salmonella coupled with the recent poor success rate of antibiotic discovery programs of the pharmaceutical industry is a cause for significant concern. It has forced the scientific community to look for alternative new classes of antimicrobial compounds. In this context, combinations of antimicrobial peptides (AMPs) and conventional antibiotics have gained interest owing to their versatile applications. The present study was therefore planned to evaluate the synergistic effects, if any, of cryptdin-2, a mouse Paneth cell alpha-defensin, in combination with four different antibiotics i.e. ciprofloxacin, ceftriaxone, cefotaxime and chloramphenicol, which are conventionally used against Salmonella. Minimum bactericidal concentrations of the selected antimicrobial agents were determined by micro and macro broth dilution assays. In-vitro synergy between the agents was evaluated by fractional bactericidal concentration index (checkerboard test) and time-kill assay. Cryptdin-2-ciprofloxacin, cryptdin-2-ceftriaxone and cryptdin-2-cefotaxime combinations were found synergistic as evident by in vitro assays. This synergism provides an additional therapeutic choice by allowing the use of conventional antibiotics in conjunction with AMPs against MDR Salmonella.     

Dimethylarginine Levels in Cerebrospinal Fluid of Hyperacute Ischemic Stroke Patients are Associated with Stroke Severity

We hypothesise that asymmetric and symmetric dimethylarginine (ADMA, SDMA) are released in cerebrospinal fluid (CSF) due to ischemia-induced proteolysis and that CSF dimethylarginines are related to stroke severity. ADMA and SDMA were measured in CSF of 88 patients with ischemic stroke or TIA within 24 h after stroke onset (mean 8.6 h) and in 24 controls. Stroke severity was assessed by the National Institutes of Health Stroke Scale (NIHSS) score at admission. Outcome was evaluated by institutionalization due to stroke and the modified Rankin scale. Dimethylarginine levels were higher in patients with stroke than in TIA patients, who had higher levels than controls and correlated with the NIHSS. Logistic regression analysis confirmed that dimethylarginines were independently associated with stroke severity. The SDMA/ADMA ratio did not differ significantly between controls and stroke patients. CSF dimethylarginine levels are increased in hyperacute ischemic stroke and are associated with stroke severity. R. Brouns is a research assistant of the Fund for Scientific research Flanders (FWO-Vlaanderen).     

In vitro identification and characterisation of iron chelating catechol-containing natural products and derivatives

BioMetals - Iron is an essential component for multiple biological processes. Its regulation within the body is thus tightly controlled. Dysregulation of iron levels within the body can result in...     

Oxylipin biosynthesis reinforces cellular senescence and allows detection of senolysis

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