Light-induced reversible reorganizations in closed Type II reaction centre complexes: physiological roles and physical mechanisms

The purpose of this review is to outline our understanding of the nature, mechanism and physiological significance of light-induced reversible reorganizations in closed Type II reaction centre (RC) complexes. In the so-called 'closed' state, purple bacterial RC (bRC) and photosystem II (PSII) RC complexes are incapable of generating additional stable charge separation. Yet, upon continued excitation they display well-discernible changes in their photophysical and photochemical parameters. Substantial stabilization of their charge-separated states has been thoroughly documented-uncovering light-induced reorganizations in closed RCs and revealing their physiological importance in gradually optimizing the operation of the photosynthetic machinery during the dark-to-light transition. A range of subtle light-induced conformational changes has indeed been detected experimentally in different laboratories using different bRC and PSII-containing preparations. In general, the presently available data strongly suggest similar structural dynamics of closed bRC and PSII RC complexes, and similar physical mechanisms, in which dielectric relaxation processes and structural memory effects of proteins are proposed to play important roles.

New insights of phenolic compounds from optimized fruit extract of Ficus auriculata

In this study, the extraction conditions extracted maximize amounts of phenolic and bioactive compounds from the fruit extract of Ficus auriculata by using optimized response surface methodology. The antioxidant capacity was evaluated through the assay of radical scavenging ability on DPPH and ABTS as well as reducing power assays on total phenolic content (TPC). For the extraction purpose, the ultrasonic assisted extraction technique was employed. A second-order polynomial model satisfactorily fitted to the experimental findings concerning antioxidant activity (R2 = 0.968, P < 0.0001) and total phenolic content (R2 = 0.961, P < 0.0001), indicating a significant correlation between the experimental and expected value. The highest DPPH radical scavenging activity was achieved 85.20 ± 0.96% at the optimum extraction parameters of 52.5% ethanol (v/v), 40.0 °C temperature, and 22 min extraction time. Alternatively, the highest yield of total phenolic content was found 31.65 ± 0.94 mg GAE/g DF at the optimum extraction conditions. From the LC-ESI-MS profiling of the optimized extract, 18 bioactive compounds were tentatively identified, which may regulate the antioxidant activity of fruits of F. auriculata.

In vitro antioxidant activity of Ficus carica L. latex from 18 different cultivars

As synthetic antioxidants that are widely used in foods are known to cause detrimental health effects, studies on natural additives as potential antioxidants are becoming increasingly important. In this work, the total phenolic content (TPC) and antioxidant activity of Ficus carica Linn latex from 18 cultivars were investigated. The TPC of latex was calculated using the Folin–Ciocalteu assay. 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ferric ion reducing antioxidant power (FRAP) were used for antioxidant activity assessment. The bioactive compounds from F. carica latex were extracted via maceration and ultrasound-assisted extraction (UAE) with 75% ethanol as solvent. Under the same extraction conditions, the latex of cultivar ‘White Genoa’ showed the highest antioxidant activity of 65.91% ± 1.73% and 61.07% ± 1.65% in DPPH, 98.96% ± 1.06% and 83.04% ± 2.16% in ABTS, and 27.08 ± 0.34 and 24.94 ± 0.84 mg TE/g latex in FRAP assay via maceration and UAE, respectively. The TPC of ‘White Genoa’ was 315.26 ± 6.14 and 298.52 ± 9.20 µg GAE/mL via the two extraction methods, respectively. The overall results of this work showed that F. carica latex is a potential natural source of antioxidants. This finding is useful for further advancements in the fields of food supplements, food additives and drug synthesis in the future.

Evaluating feasibility and acceptability of a group WHO trans-diagnostic intervention for women with common mental disorders in rural Pakistan: a cluster randomised controlled feasibility trial

AIMS

The aim of this feasibility trial was to evaluate the feasibility and acceptability of the locally adapted Group Problem Management Plus (PM+) intervention for women in the conflict affected settings in Swat, Pakistan.

METHODS

This mixed-methods study incorporated a quantitative component consisting of a two arm cluster randomised controlled feasibility trial, and qualitative evaluation of the acceptability of the Group PM+ to a range of stakeholder groups. For the quantitative component, on average from each of the 20 Lady Health Workers (LHWs) catchment area (20 clusters), six women were screened and recruited for the trial with score of >2 on the General Health Questionnaire and score of >16 on the WHO Disability Assessment Schedule. These LHW clusters were randomised on a 1 : 1 allocation ratio using a computer-based software through a simple randomisation method to the Group PM+ intervention or Enhanced Usual Care. The Group PM+ intervention consisted of five weekly sessions of 2 h duration delivered by local non-specialist females under supervision. The primary outcome was individual psychological distress, measured by levels of anxiety and depression on the Hospital Anxiety and Depression Scale at 7th week after baseline. Secondary outcomes include symptoms of depression, post-traumatic stress disorder (PTSD), general psychological profile, levels of functioning and generalised psychological distress. Intervention acceptability was explored through in-depth interviews.

RESULTS

The results show that lay-helpers with no prior mental health experience can be trained to achieve the desired competency to successfully deliver the intervention in community settings under supervision. There was a good intervention uptake, with Group PM+ considered useful by participants, their families and lay-helpers. The outcome evaluation, which was not based on a large enough study to identify statistically significant results, indicated statistically significant improvements in depression, anxiety, general psychological profile and functioning. The PTSD symptoms and depressive disorder scores showed a trend in favour of the intervention.

CONCLUSION

This trial showed robust acceptance in the local settings with delivery by non-specialists under supervision by local trained females. The trial paves the way for further adaptation and exploration of the outcomes through larger-scale implementation and definitive randomised controlled trials in the local settings.

Degradation and mineralization of methylene blue using a heterogeneous photo-Fenton catalyst under visible and solar light irradiation

A SiO₂-supported Fe and Ni bimetallic catalyst has been synthesized, characterized and, for the first time, tested as a heterogeneous photo-Fenton catalyst for the degradation and mineralization of methylene blue (MB) dye.

Partition controlled delivery of hydrophobic substances in toxicity tests using poly(dimethylsiloxane) (PDMS) films

Interpretation of toxicity test results may be hampered when doubt exists about the actual exposure concentration. Processes that are responsible for differences between the nominal and the actual concentration in aqueous test systems may include sorption, precipitation, volatilization, chemical and biological degradation, and uptake into biological or test tissue. In this study, the use of a poly(dimethylsiloxane) (PDMS) film containing the test compound is introduced as a versatile technique for partition controlled delivery of hydrophobic compounds to aqueous toxicity tests. Two methods developed produced preloaded films, having toxicant added to the PDMS prepolymer solution before film deposition and curing, and postloaded films, which are created by the addition of toxicant in a solvent to an already-polymerized PDMS film. Preloaded films were generally more easily prepared, may better accommodate larger molecules, and have a higher capacity than postloaded films. Postloaded films provided film-solution partition coefficients with higher precision and allowed for the use of films from stock and thus for a more portable technique. Chemical analysis showed that equilibrium between films and the aqueous solution was established within 7-10 min and was maintained for a suite of aromatic compounds (log Kow ranging from 2.8 to 6.1). The reliability of the film technique was demonstrated by application to the Microtox bacterial toxicity tests of solutions of polycyclic aromatic hydrocarbons (PAHs).

Plasmodium falciparum and hepatitis E virus co-infection in fulminant hepatic failure

Acute hepatitis E and falciparum malaria can each present with fulminant hepatic failure and are common in tropical countries. However, co-existence of these two conditions has not been reported. We report a 20-year-old girl who presented with fever and altered sensorium. Peripheral smear was positive for Plasmodium falciparum, and IgM anti-HEV was positive. She died despite antimalarial drugs and supportive management. Postmortem liver tissue showed changes suggestive of acute viral hepatitis.

Complete sequence of the IncPbeta plasmid R751: implications for evolution and organisation of the IncP backbone

The broad host range IncP plasmids are of particular interest because of their ability to promote gene spread between diverse bacterial species. To facilitate study of these plasmids we have compiled the complete sequence of the IncPbeta plasmid R751. Comparison with the sequence of the IncPalpha plasmids confirms the conservation of the IncP backbone of replication, conjugative transfer and stable inheritance functions between the two branches of this family. As in the IncPalpha genome the DNA of this backbone appears to have been enriched for the GCCG/CGGC motifs characteristic of the genome of organisms with a high G+C content, such as P. aeruginosa, suggesting that IncPbeta plasmids have been subjected during their evolution to similar mutational and selective forces as IncPalpha plasmids and may have evolved in pseudomonad hosts. The IncP genome is consistently interrupted by insertion of phenotypic markers and/or transposable elements between oriV and trfA and between the tra and trb operons. The R751 genome reveals a family of repeated sequences in these regions which may form the basis of a hot spot for insertion of foreign DNA. Sequence analysis of the cryptic transposon Tn4321 revealed that it is not a member of the Tn21 family as we had proposed previously from an inspection of its ends. Rather it is a composite transposon defined by inverted repeats of a 1347 bp IS element belonging to a recently discovered family which is distributed throughout the prokaryotes. The central unique region of Tn4321 encodes two predicted proteins, one of which is a regulatory protein while the other is presumably responsible for an as yet unidentified phenotype. The most striking feature of the IncPalpha plasmids, the global regulation of replication and transfer by the KorA and KorB proteins encoded in the central control operon, is conserved between the two plasmids although there appear to be significant differences in the specificity of repressor-operator interactions. The importance of these global regulatory circuits is emphasised by the observation that the operator sequences for KorB are highly conserved even in contexts where the surrounding region, either a protein coding or intergenic sequence, has diverged considerably. There appears to be no equivalent of the parABCDE region which in the IncPalpha plasmids provides multimer resolution, lethality to plasmid-free segregants and active partitioning functions. However, we found that the continuous sector from co-ordinate 0 to 9100 bp, encoding the co-regulated klc and kle operons as well as the central control region, could confer a high degree of segregational stability on a low copy number test vector. Thus R751 appears to exhibit very clearly what was first revealed by study of the IncPalpha plasmids, namely a fully functional co-ordinately regulated set of replication, transfer and stable inheritance functions.

Role of atrial ischaemia in development of atrial fibrillation following coronary artery bypass surgery

OBJECTIVE

Atrial fibrillation (AF) is a common complication after coronary artery bypass grafting (CABG) operations, occurring in 5 to 40% of cases. A number of studies have implicated atrial ischaemia in the genesis of this arrhythmia. The aim of this study was to examine the relationship between atrial coronary anatomy and the incidence of post operative atrial fibrillation.

METHOD

To investigate a possible anatomical explanation to the onset of AF after CABG, 25 patients with documented AF after CABG were matched and compared to 25 patients which remained in sinus rhythm (SR). All coronary angiograms were reported blindly by a cardiac radiologist with reference to the blood supply of the sino-atrial (SA) node and atrio-ventricular (AV) node before and after surgery.

RESULTS

Univariate analysis of risk factors did not identify any significant difference (Fisher exact test, P > 0.05) between the two groups in age, gender, left ventricular function, ischaemic time, number of vessels diseased or grafted, renal dysfunction and withdrawal of beta-blockade. However, significant disease in the SA nodal artery was present in 2 patients of the SR group when compared to 9 in the AF group. Significant disease of AV nodal artery was present in only 4 patients of the SR group when compared to 18 in the AF group. Comparison between the two groups showed a significantly increased incidence of SA or AV nodal artery disease in the AF group, (SA: P = 0.018, AV: P = 0.0001). Mean hospital stay was 8.1 days for the SR group and 9.1 days in the AF group (P = 0.175).

CONCLUSION

Obstructive disease in the SA nodal and AV nodal arteries is more common in patients developing atrial fibrillation following coronary artery bypass surgery than those who remain in sinus rhythm. If the incidence of AF could be predicted by the anatomical distribution of arterial disease then targeting prophylaxis to this group may be possible.