Structural evidence for intermediates during O2 formation in photosystem II.

In natural photosynthesis, the light-driven splitting of water into electrons, protons and molecular oxygen forms the first step of the solar-to-chemical energy conversion process. The reaction takes place in photosystem II, where the Mn4CaO5 cluster first stores four oxidizing equivalents, the S0 to S4 intermediate states in the Kok cycle, sequentially generated by photochemical charge separations in the reaction center and then catalyzes the O-O bond formation chemistry1-3. Here, we report room temperature snapshots by serial femtosecond X-ray crystallography to provide structural insights into the final reaction step of Kok's photosynthetic water oxidation cycle, the S3→[S4]→S0 transition where O2 is formed and Kok's water oxidation clock is reset. Our data reveal a complex sequence of events, which occur over micro- to milliseconds, comprising changes at the Mn4CaO5 cluster, its ligands and water pathways as well as controlled proton release through the hydrogen-bonding network of the Cl1 channel. Importantly, the extra O atom Ox, which was introduced as a bridging ligand between Ca and Mn1 during the S2→S3 transition4-6, disappears or relocates in parallel with Yz reduction starting at approximately 700 µs after the third flash. The onset of O2 evolution, as indicated by the shortening of the Mn1-Mn4 distance, occurs at around 1,200 µs, signifying the presence of a reduced intermediate, possibly a bound peroxide.

On the simulation and interpretation of substrate-water exchange experiments in photosynthetic water oxidation.

Water oxidation by photosystem II (PSII) sustains most life on Earth, but the molecular mechanism of this unique process remains controversial. The ongoing identification of the binding sites and modes of the two water-derived substrate oxygens ('substrate waters') in the various intermediates (Si states, i = 0, 1, 2, 3, 4) that the water-splitting tetra-manganese calcium penta-oxygen (Mn4CaO5) cluster attains during the reaction cycle provides central information towards resolving the unique chemistry of biological water oxidation. Mass spectrometric measurements of single- and double-labeled dioxygen species after various incubation times of PSII with H218O provide insight into the substrate binding modes and sites via determination of exchange rates. Such experiments have revealed that the two substrate waters exchange with different rates that vary independently with the Si state and are hence referred to as the fast (Wf) and the slow (WS) substrate waters. New insight for the molecular interpretation of these rates arises from our recent finding that in the S2 state, under special experimental conditions, two different rates of WS exchange are observed that appear to correlate with the high spin and low spin conformations of the Mn4CaO5 cluster. Here, we reexamine and unite various proposed methods for extracting and assigning rate constants from this recent data set. The analysis results in a molecular model for substrate-water binding and exchange that reconciles the expected non-exchangeability of the central oxo bridge O5 when located between two Mn(IV) ions with the experimental and theoretical assignment of O5 as WS in all S states. The analysis also excludes other published proposals for explaining the water exchange kinetics.

Reliability of low-flow anesthesia procedures in patients undergoing laparoscopic cholecystectomy: Their effects on our costs and ecological balance.

Background and Aim: The many advantages of low-flow anesthesia are now recognized. Apart from its positive effects on the patient, it is clear that it is a method that all anesthetists should prefer with its positive effects on the ecological balance. Patients and Methods: This prospective, observational, cross-sectional study included 80 patients aged 18-65 years with an American Society of Anesthesiologists score of 1-2 (ASA I-II) who were scheduled for laparoscopic cholecystectomy. Results: Although the operation time and anesthesia duration were higher in the low anesthesia group group, sevoflurane consumption was lower. Considering the operation times, up to 60% savings were achieved. Conclusion: In our study, we safely applied low-flow anesthesia to our patients with advanced monitoring. We believe that low-flow anesthesia is advantageous in terms of both patients' health, ecological balance, and cost.

Reconnaissance of tumor immune microenvironment spatial heterogeneity in metastatic renal cell carcinoma and correlation with immunotherapy response.

A clearer understanding of the tumor immune microenvironment (TIME) in metastatic clear cell renal cell carcinoma (ccRCC) may help to inform precision treatment strategies. We sought to identify clinically meaningful TIME signatures in ccRCC. We studied tumors from 39 patients with metastatic ccRCC using quantitative multiplexed immunofluorescence and relevant immune marker panels. Cell densities were analyzed in three regions of interest (ROIs): tumor core, tumor-stroma interface and stroma. Patients were stratified into low- and high-marker density groups using median values as thresholds. Log-rank and Cox regression analyses while controlling for clinical variables were used to compare survival outcomes to patterns of immune cell distributions. There were significant associations with increased macrophage (CD68+ CD163+ CD206+ ) density and poor outcomes across multiple ROIs in primary and metastatic tumors. In primary tumors, T-bet+ T helper type 1 (Th1) cell density was highest at the tumor-stromal interface (P = 0·0021), and increased co-expression of CD3 and T-bet was associated with improved overall survival (P = 0·015) and survival after immunotherapy (P = 0·014). In metastatic tumor samples, decreased forkhead box protein 3 (FoxP3)+ T regulatory cell density correlated with improved survival after immunotherapy (P = 0·016). Increased macrophage markers and decreased Th1 T cell markers within the TIME correlated with poor overall survival and treatment outcomes. Immune markers such as FoxP3 showed consistent levels across the TIME, whereas others, such as T-bet, demonstrated significant variance across the distinct ROIs. These findings suggest that TIME profiling outside the tumor core may identify clinically relevant associations for patients with metastatic ccRCC.

The effect of 1,25-dihydroxyvitamin D3 on liver damage, oxidative stress, and advanced glycation end products in experimental nonalcoholic- and alcoholic- fatty liver disease

Background/aim: Oxidative stress and advanced glycation end products (AGEs) formation are proposed as effective mechanisms in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD). 1,25(OH)2D3 was proposed to have antioxidant, antiinflammatory and antiglycation properties. In this study, the effect of 1,25(OH)2D3 treatment on oxidative stress parameters and AGEs levels together with hepatic histopathology was investigated in high fructose (HFr) or ethanol (EtOH)-treated rats. Materials and methods: Rats were treated with fructose (30%) or ethanol (5-20%) in drinking water with and without 1,25(OH)2D3 treatment (5 µg/kg two times a week) for 8 weeks. Insulin resistance (IR), oxidative stress parameters, AGEs, triglyceride (TG), and hydroxyproline (Hyp) levels together with histopathology were investigated in the liver. Results: 1,25(OH)2D3 decreased hepatic reactive oxygen species, lipid and protein oxidation products together with histopathological improvements in HFr- and EtOH-treated rats. 1,25(OH)2D3 treatment was observed to decrease significantly serum and hepatic AGEs in HFr group, and hepatic AGEs in EtOH group. Conclusion: Our results clearly show that 1,25(OH)2 D3 treatment may be useful in the alleviation of hepatic lesions by decreasing glycooxidant stress in both NAFLD and ALD models created by HFr- and EtOH-treated rats, respectively.

The endothelin 1 and endothelin receptor A gene polymorphisms increase the risk of developing papillary thyroid cancer.

The endothelin (EDN) axis (EDN1 and EDN1 receptor A, EDNRA) is involved in cellular growth, differentiation, invasiveness, and tumor progression in several cancers. We wanted to examine the possible impact of single nucleotide polymorphisms (SNPs) of EDN1 and EDNRA genes on papillary thyroid cancer (PTC) development and general characteristics of PTC. Study population consist of 113 PTC patients and 185 controls. EDN1 (G5665T, T-1370G) and EDNRA (C TT70G, G-231A) SNPs were investigated by real-time PCR. The GG genotype of EDNRA + 70 SNP was associated with threefold increased PTC risk (p = 0.01), and the combined CG + GG genotype was 2.48 fold higher among PTC patients compared to controls. The variant EDNRA - 231 allele was overrepresented in PTC patients according to controls (p = 0.05). The combined GT + TT genotype of EDN1 5665 SNP was related with late (age after 40 years) PTC onset (p = 0.04), and was more prominent among male patients with PTC according to females (p = 0.03). No significant associations between PTC and - 1370 SNP were found. There were no relationships between laboratory parameters and investigated polymorphisms. The EDNRA + 70 SNP was associated with PTC development. The EDN1 5665 SNP was linked with increased risk for late PTC onset and was more prominent among male patients with PTC.

Nocturnal blood pressure dipping is similar in rheumatoid arthritis patients as compared to a normal population.

OBJECTIVE: Rheumatoid arthritis (RA) is a systemic autoimmune inflammatory disorder which further doubles the risk of developing cardiovascular disease. Some studies suggest that in RA patients, the prevalence of hypertension increases due to prednisolone use, clinical status, genetic factors, and physical inactivity. On the other hand, dipper and non-dipper status in RA patients compared to non-RA subjects has not been investigated to our knowledge. Purpose of the study is to investigate whether non-dipper status is more deteriorated in RA patients. METHODS: Sixty-five RA patients and 61 age-sex-matched control patients were evaluated in this cross-sectional study. Patients were classified according to 24-h ambulatory blood pressure monitoring results. Patients with previous hypertension diagnosis, coronary artery disease, and abnormal kidney function were excluded. RESULTS: Mean age of the study sample was 53.7 ± 12.3 years and 40.5% were male. There was no significant difference between groups in terms of basic demographic characteristics. Leukocyte counts (p = 0.001), neutrophil counts (p = 0.001), and red cell distribution width (p = 0.000) were significantly higher in the RA group. ABPM results indicate no significant difference between RA patients and the control group in terms of daytime systolic and diastolic blood pressure, nighttime systolic and diastolic blood pressure, and average systolic and diastolic blood pressure results (p > 0.05). There was no statistical difference regarding the non-dipper status of patient groups (p = 0.412). Nocturnal blood pressure dipping was significantly similar between groups (p = 0.980). CONCLUSION: In conclusion, RA patients have similar values in terms of nocturnal blood pressure dipping and hypertension diagnosis as compared to normal population.

Holistic nursing competence scale: Turkish translation and psychometric testing.

AIM: This study aimed to culturally adapt and evaluate the reliability and validity of the Holistic Nursing Competence Scale for application in the Turkish context. BACKGROUND: Nurses are expected to assess well-being of individuals by considering physical, social, psychological, cultural and spiritual dimensions to enhance adaptation to diseases. In Turkey, no tools have been developed to date for the evaluation of competencies in holistic nursing in the country. METHODS: The study was conducted with 288 nurses working in two hospitals in Ankara equipped with over 500 beds. A confirmatory factor analysis was performed in order to identify whether the items and the sub-dimensions of the adapted scale complied with the original structure comprising 36 items and five sub-scales, namely 'general aptitude', 'staff education and management', 'ethically oriented practice', 'nursing care in a team' and 'professional development'. Cronbach's alpha value was used as an estimate for reliability analysis. RESULTS: Opinions of 11 experts were obtained for content validation of the scale, and the content validity index was 0.90. The adaptation was observed to be acceptable on the basis of structural equation model fit indices in confirmatory factor analysis. Cronbach's alpha value was estimated to be 0.97 and 0.90, respectively, for the complete scale. CONCLUSION: The study identified the Turkish version of Holistic Nursing Competence Scale as a valid and reliable tool for the evaluation of competence in holistic nursing among nurses. IMPLICATIONS FOR NURSING AND NURSING POLICY: The instrument may now be utilized as a tool of measurement in nursing practice, as well as in education and research, for identifying the level of competence in the holistic nursing practices among the nurses in Turkey.

N-Acetylcysteine supplementation decreased brain lipid and protein oxidations produced by experimental homocysteine thiolactone exposure: Relevance to neurodegeneration.

High levels of homocysteine (Hcy) have neurotoxic effects. Homocysteine thiolactone (HcyT), a thioester of Hcy, plays a role in Hcy-induced toxicity. In this study, effects of HcyT treatment (500 mg/kg body weight/day in drinking water) for 6 weeks on serum Hcy levels and brain prooxidant-antioxidant balance were investigated in rats. The effect of N-acetylcysteine (NAC) treatment (1 g/kg body weight/day in chow) for 6 weeks on HcyT-induced neurotoxicity was evaluated. Reactive oxygen species (ROS), thiobarbituric acid reactive substances (TBARS), diene conjugate (DC), protein carbonyl (PC) and advanced oxidation protein products (AOPP) were determined in the brain tissue. Ferric reducing antioxidant power (FRAP) and non-protein sulfydryl groups (NPSH) levels as well as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were also measured to evaluate the antioxidant potential of brain the tissue. HcyT elevated serum Hcy levels and brain ROS, TBARS, DC, PC and AOPP levels. However, HcyT did not affect FRAP levels and SOD, and GSH-Px activities. NAC treatment decreased serum Hcy and brain ROS, TBARS, DC, PC and AOPP levels in HCyT-treated rats. Our results indicate that NAC supplementation may be effective in decreasing serum Hcy levels and HcyT-induced oxidative stress in brain of rats.

Carnosine prevents testicular oxidative stress and advanced glycation end product formation in D-galactose-induced aged rats.

D-Galactose is shown to mimic natural ageing in rodents by exacerbating oxidative stress and glycation. Steroid production and having a poor antioxidant system make testis vulnerable to galactose-induced ageing. Antioxidation and antiglycating actions of carnosine may be intriguing for prevention of testicular ageing. In this study, male Wistar rats were applied D-galactose (300 mg/kg; subcutaneously 5 days a week) and carnosine (250 mg/kg; intraperitoneally 5 days a week) along with D-galactose for 2 months. D-Galactose treatment increased testicular reactive oxygen species, thiobarbituric acid reactive substances, diene conjugates, protein carbonyls, advanced oxidation products of proteins and advanced glycation end products. Carnosine was capable of repelling oxidative stress and glycation produced by D-galactose. Johnsen's score, which describes histopathological evaluation, was also significantly improved with preserved spermatogenesis by carnosine. It appears that carnosine deters the testicular oxidative stress due to galactose-induced ageing directly by its antioxidative and antiglycating properties.

Evaluation of High Performance Liquid Chromatography and Liquid Chromatography-Tandem Mass Spectrometry Methods for 25 (OH) D3 Assay.

BACKGROUND: This study was designed to compare the performances of HPLC (High Performance Liquid Chromatography) and LC-MS/MS (Liquid Chromatography-Tandem Mass Spectrometry) methods in 25 (OH) D3 testing. METHODS: This study is comprised of 306 randomly chosen plasma samples from the subjects who applied for routine measurement of 25 (OH) D3. Plasma 25 (OH) D3 levels were quantified using HPLC and LC-MS/MS. The LC-MS/MS method was used as the reference method. The linearity, precision, carry-over, limit of blank, limit of detection (LoD), and comparison studies were done for method validation. Accuracy was tested using external quality assurance samples. RESULTS: Coefficients of variation for both methods were at around 10.0%. The HPLC and LC-MS/MS assays were linear over the working range from 5.0 to 100 ng/mL (r > 0.99). The HPLC assay showed a higher LoD compared to LC-MS/MS (5.1 vs. 1.6 ng/mL, respectively). Results from external quality assurance samples were within ? 1 SD range for both methods. The comparison study revealed good correlation between HPLC and LC-MS/MS methods (y = 1.054x - 1.981 with a small mean bias (-0.953) (r = 0.9752)), when all samples were included, regardless of their 25 (OH) D3 levels. However, the correlation was poor for samples with 25 (OH) D3 concentrations lower than 10 ng/mL. CONCLUSIONS: Both methods have acceptable performance characteristics for use in clinical diagnostic applications. A good comparability was obtained between HPLC and LC-MS/MS methods. However, LoD of HPLC assay was higher and there was a poor correlation between the two systems for samples with 25 (OH) D3 concentrations below 10 ng/mL, showing that LC-MS/MS system is more successful in measuring samples with low 25 (OH) D3 concentration.

Carnosine and taurine treatments diminished brain oxidative stress and apoptosis in D-galactose aging model.

D-galactose (GAL) has been used as an animal model for brain aging and antiaging studies. GAL stimulates oxidative stress in several tissues including brain. Carnosine (CAR; ß-alanil-L-histidine) and taurine (TAU; 2-aminoethanesulfonic acid) exhibit antioxidant properties. CAR and TAU have anti-aging and neuroprotective effects. We investigated the effect of CAR and TAU supplementations on oxidative stress and brain damage in GAL-treated rats. Rats received GAL (300 mg/kg; s.c.; 5 days per week) alone or together with CAR (250 mg/kg/daily; i.p.; 5 days per week) or TAU (2.5% w/w; in rat chow) for 2 months. Brain malondialdehyde (MDA), protein carbonyl (PC) and glutathione (GSH) levels and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione transferase (GST) and acetylcholinesterase (AChE) activities were determined. Expressions of B cell lymphoma-2 (Bcl-2), Bax and caspase-3 were also evaluated in the brains by immunohistochemistry. GAL treatment increased brain MDA and PC levels and AChE activities. It decreased significantly brain GSH levels, SOD and GSH-Px but not GST activities. GAL treatment caused histopathological changes and increased apoptosis. CAR and TAU significantly reduced brain AChE activities, MDA and PC levels and elevated GSH levels in GAL-treated rats. CAR, but not TAU, significantly increased low activities of SOD and GSH-Px. Both CAR and TAU diminished apoptosis and ameliorated histopathological findings in the brain of GAL-treated rats. Our results indicate that CAR and TAU may be effective to prevent the development of oxidative stress, apoptosis and histopathological deterioration in the brain of GAL-treated rats.

Possible alendronate-induced polyarticular synovitis.

We present a case of polyarticular synovitis following alendronate treatment for osteoporosis. The patient had no evidence of rheumatoid arthritis, pyrophosphate arthropathy, or seronegative/seropositive arthritis. Our main aim in this study is to highlight the potential adverse effects of alendronate and to warn orthopedic surgeons about the possibility of such a side effect that might lead orthopedic surgeons to administer wrong and unnecessary treatments like arthrocentesis. The withdrawal of alendronate is found to be the treatment of choice. Alendronate should be considered as a possible cause of synovitis or polyarthritis in patients treated with this agent in the absence of any other pathology. An association between alendronate and synovitis has rarely been described in the literature. We present a patient who developed polyarticular synovitis after treatment with alendronate and responded to its withdrawal.

Immediate risk of HSIL presence in women who have both ASC-US cytology and negative high-risk HPV test.

PURPOSE: The authors aimed to detect immediate risk of having high grade squamous lesions (HSIL) in atypical squamous cells of uncertain significance(AS-CUS) and concomitant high-risk human papillomavirus (HrHPV) testing as negative [HrHPV(negative)AS-CUS]. MATERIALS AND METHODS: The authors performed immediate/baseline colposcopy on concomitant HrHPV (negative)AS-CUS cases. Pap tests were evaluated with liquid-based cytology (LBC) and HrHPV detection was performed in LBC material with PCR. Colposcopic diagnoses and biopsy results were compared with Pap test and HrHPV test results. RESULTS: There were 104 patients over a one-year period. In all, 84 cases were included. Colposcopic biopsies revealed low grade squamous intraepithelial lesion (LSIL) in 19 cases (23%) and HSIL in three cases (4%). Intrauterine device use and smoking were significantly correlated with presence of HSIL (p = 0.005 and p = 0.007 respectively). CONCLUSION: Similar data in literature, 4% of ASC-US-HrHPV (negative) cases are expected to have HSIL in follow-up periods less than six months. The present authors believe clinicians should be more open with their patients about limitations of Pap-HPV testing.

Erratum:Preoperative neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio as new prognostic factors for patients with colorectal cancer.

In this article published in Volume 21, issue 5, the authors' names appeared in the Pubmed abstract as: "Mahsuni Sevinc M, Riza Gunduz U, Kinaci E, Armagan Aydin A, Bayrak S, Umar Gursu R, Gunduz S". The correct authors' names are: "Sevinc MM, Gunduz UR, Kinaci E, Aydin AA, Bayrak S, Gursu RU, Gunduz S" This error appeared only in the PubMed database and not in the print form of the Journal.

Blueberry treatment decreased D-galactose-induced oxidative stress and brain damage in rats.

D-galactose (GAL) causes aging-related changes and oxidative stress in the organism. We investigated the effect of whole fresh blueberry (BB) (Vaccinium corymbosum L.) treatment on oxidative stress in age-related brain damage model. Rats received GAL (300 mg/kg; s.c.; 5 days per week) alone or together with 5 % (BB1) and 10 % (BB2) BB containing chow for two months. Malondialdehyde (MDA),protein carbonyl (PC) and glutathione (GSH) levels, and Cu Zn-superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione transferase (GST) activities as well as acetylcholinesterase (AChE) activities were determined. Expressions of B cell lymphoma-2 (Bcl-2), Bax and caspase-3 were also evaluated in the brain by immunohistochemistry. MDA and PC levels and AChE activity increased, but GSH levels, SOD and GSH-Px activities decreased together with histopathological structural damage in the brain of GAL-treated rats. BB treatments, especially BB2 reduced MDA and PC levels and AChE activity and elevated GSH levels and GSH-Px activity. BB1 and BB2 treatments diminished apoptosis and ameliorated histopathological findings in the brain of GAL-treated rats. These results indicate that BB partially prevented the shift towards an imbalanced prooxidative status and apoptosis together with histopathological amelioration by acting as an antioxidant (radical scavenger) itself in GAL-treated rats.

Carnosine and vitamin E--a promising pair in the combat against testicular oxidative stress in aged rats.

Oxidative stress is considered to play a key role in ageing. Carnosine alone or together with vitamin E may prove to be helpful in dealing with problems of ageing through its antioxidant activity. Testis, by producing steroids and possessing a poor antioxidant system may become a strong target for the chronic oxidative stress generated during ageing. Therefore we investigated the in vivo effect of carnosine alone or together with vitamin E on testicular oxidative stress in aged rats. In this study, young (5 months) and aged (22 months) Wistar rats were used. Carnosine (250 mg kg(-1); i.p.; 5 days per week) and vitamin E (200 mg kg(-1); i.m.; twice per week) were given to aged rats for 2 months. Increased testicular lipid peroxidation and superoxide dismutase activity in aged rats were declined to the levels of young ones by both treatments. Decreased glutathione peroxidase and glutathione transferase activities returned to the level of young's only by carnosine plus vitamin E treatment. Histopathological evaluation described by Johnsen's score, also showed significant improvement with preserved spermatogenesis. Carnosine plus vitamin E treatment appears to stage a powerful performance by attenuating testicular oxidative stress and sparing the antioxidant system.

Steroid cell tumor of the ovary associated with endometrial adenocarcinoma--a rare case report.

Endometrial carcinoma is the most common invasive neoplasm of the female genital tract and is associated to the elevated levels of unopposed estrogen, especially in postmenopause. Ovarian Steroid cell tumors are rare tumors and they are named according to the origin of cell. The most common cancer of the female genital tract is the endometrial adenocarcinoma and it accounts for 7% of all invasive cancers in women. In the present case report, the authors present a 59-year-old multiparous woman with a postmenopausal bleeding complaint and they discuss the case of ovarian steroid cell tumor associated with endometrioid adenocarcinoma of endometrium. Endometrial adenocarcinoma is the most common cancer of female genital tract and its contemporarity with an ovarian steroid cell tumor is extremely rare.

The Effect of Porcelain Firing on Electrochemical Behavior of a Dental Alloy in Hydrogen Peroxide.

PURPOSE: The aim of this study was to evaluate changes in electrochemical corrosion properties of porcelain firing simulated nickel-chromium dental casting alloy exposed to a 10% hydrogen peroxide bleaching agent. MATERIALS AND METHODS: The electrochemical corrosion behavior of a Ni-Cr alloy was evaluated by cyclic polarization test in the aerated electrolyte (pH = 6.5). Test groups were produced in as-cast (group 1, control group) and simulated porcelain firing (group 2: heat-treated/mean value; group 3: heat-treated/cycle) conditions. Scanning electron microscopy (SEM) was also used to examine the alloy surfaces before and after the corrosion test. RESULTS: The ranking of the groups with respect to Ecorr and Icorr was as follows: 1, 2, 3 and 3, 1, 2, respectively. Group 3 exhibited the greatest and group 2 displayed the least corrosion tendencies. An increase in corrosion rates was observed after heat treatment/cycle state. Post-corrosion SEM photographs were also consistent with the test results. CONCLUSION: Within the parameters of this study, a single heat treatment is insufficient to cause upheaval in corrosion behavior of a Ni-Cr alloy subjected to 10% hydrogen peroxide.