5649152
Differential distribution of pigment-protein complexes in the Thylakoid membranes of Synechocystis 6803
AbstractThylakoids in Synechocystis 6803, though apparently uniform in appearance in ultrastructure, were found to consist of segments which were functionally dissimilar and had distinct proteomes. These thylakoid segments can be isolated from Synechocystis 6803 by successive ultracentrifugation of cell free extracts at 40,000×g (40 k segments), 90,000×g (90 k segments) and 150,000×g (150 k segments). Electron microscopy showed differences in their appearance. 40 k segments looked feathery and fluffy, whereas the 90 k and 150 k thylakoid membrane segments appeared tiny and less fluffy. The absorption spectra showed heterogeneous distribution of pigment-protein complexes in the three types of segments. The photochemical activities of Photosystem I (PSI) and Photosystem II (PSII) showed unequal distributions in 40 k, 90 k and 150 k segments which were substantiated with low temperature fluorescence measurements. The ratio of PSII/PSI fluorescence emission at 77 K (λex = 435 nm) was highest in 150 k segments indicating higher PSII per unit PSI in these segments. The chlorophyll fluorescence lifetimes in the membranes, determined with a time-correlated single-photon counting technique, could be resolved in three components: τ1 
 = <40 ps, τ2 
 = 425–900 ps and τ3 
 = 2.4–3.2 ns. The percentage contribution of the fastest component (τ1) decreased in the order 40 k > 90 k > 150 k segments whereas that of the other two components showed a reversed trend. These studies indicated differential distribution of pigment-protein complexes in the three membrane segments suggesting heterogeneity in the thylakoids of Synechocystis 6803.
30418051
Heterogeneity in thylakoid membrane proteome of Synechocystis 6803.
Cell-free extracts of Synechocystis 6803 were fractionated by successive ultracentrifugation at 40,000 x g, 90,000 x g and 150,000 x g to obtain the three thylakoid fractions designated as 40k, 90k and 150k fractions respectively. These fractions showed differences in absorption and emission spectra. Nano-LC-ESI-Q-TOF MS analysis identified 123 proteins belonging to membrane as well as cytosolic fraction. Out of these proteins, there were 22 proteins with transmembrane helices and 12 proteins with signal peptide. There were 77 proteins common across all the three fractions. Most of these proteins were subunits of photosynthetic complexes, CF(0)-CF(1) ATP synthase or ribosomal proteins. Among the rest of the proteins, 8 were exclusive to 40k fraction, 3 were exclusive to 90k fraction and 13 were exclusive to 150k fraction. There were 10 proteins common between 40k and 90k fractions and 12 proteins common between 90k and 150k fractions. There were no common proteins detected between 40k and 150 fractions. The results suggested existence of heterogeneity in thylakoids of Synechocystis 6803, which may lead to micro-compartmentation and functional heterogeneity in the thylakoids of this organism as seen previously.
34997993
Iron, oxidative stress, and clinical outcomes
It is well known that iron is pro-oxidant. Chronic kidney disease (CKD) is a pro-oxidant state, and intravenous administration of iron is frequently used to correct anemia. On one hand, there is little doubt that iron causes oxidative stress. On the other, it is far from clear whether oxidative stress, so generated, leads to poor clinical outcomes. Iron has benefits that may be independent of the correction of anemia. Furthermore, concerns surround the use of high doses of erythropoietin in causing excess heart failure and death in patients with CKD. Thus, it would be prudent if iron were to continue to be used judiciously in patients who require erythropoietin. Iron, given orally, would be the preferred first-line agent in patients not on hemodialysis. In patients with sepsis, intravenous treatment with iron should be avoided, because, in animal experiments, intravenous administration of iron can compound the inflammatory response and increase mortality. Clinical trials are needed to ascertain the risk and benefits of the intravenous administration of iron in patients with CKD.
22628373
What is the current place of azoles in allergic bronchopulmonary aspergillosis and severe asthma with fungal sensitization
Evaluation of: Chishimba L, Niven RM, Cooley J, Denning DW. Voriconazole and posaconazole improve asthma severity in allergic bronchopulmonary aspergillosis and severe asthma with fungal sensitization. J. Asthma 49(4), 423–433 (2012). Allergic bronchopulmonary aspergillosis (ABPA) is a pulmonary disorder caused by hypersensitivity to Aspergillus fumigatus that usually complicates the disease course of patients with asthma and cystic fibrosis. Oral corticosteroids are currently the treatment of choice for ABPA. Another active target is the use of azoles, which act by reducing the antigenic stimulus secondary to a decreased fungal burden. Studies suggest that itraconazole compared with placebo can improve symptoms in ABPA, decrease the immunological severity (IgE levels and total eosinophil counts), glucocorticoid requirement and the number of acute ABPA exacerbations. Severe asthma with fungal sensitization, a disorder closely related to ABPA, is a specific phenotype of asthma characterized by severe asthma and evidence of fungal sensitization after exclusion of ABPA. Again, oral itraconazole has been found to improve the quality of life in these steroid-dependent asthma patients. The current retrospective study evaluated the use of newer azoles (voriconazole and posaconazole) in adult asthmatic patients with either ABPA or severe asthma with fungal sensitization, and found the newer azoles to improve asthma control and reduce the severity of ABPA.
21032742
Evaluation of carcinogenic effect of jute batching oil (JBO-P) fractions following topical application to mouse skin
Jute batching oil (JBO-P), a mineral oil fraction used in the processing of jute fibers, was, as reported in our earlier studies, found to be tumorigenic following repeated topical application to mouse skin. In the present investigation an attempt has been made to identify the carcinogenic constituents of this oil. The JBO was fractionated into (1) PAH free fraction, (2) fraction containing twoand three-ring PAHs and (3) more than three-ring PAH fractions by an enrichment procedure. These three JBO fractions along with unfractionated and reconstituted oil were then subjected to the in vivo assay of complete carcinogenic activity of JBO-P and its fractions following its topical application to mouse skin. The results showed that only unfractionated and reconstituted JBO-P samples per se were able to produce benign skin tumours, while all the other three fractions, i.e. PAH-free fraction, two- and three-ring PAH-containing fraction and more than threering PAH-containing fraction failed to produce tumours up to 40 weeks after application. In an extended study, mice belonging to the groups exposed to various fractions of JBO were promoted with 12-O-tetradecanoyl phorbol-13-acetate (TPA), a potent skin tumour promoter, for the two stage initiation-promotion protocol for skin carcinogenesis. After 14 weeks of promotion with TPA, all the surviving animals exposed to the fraction having more than three-ring PAHs developed benign tumours on their backs, while the other two fractions failed to do so. In view of these findings it can be concluded that none of the three JBO-P fractions possess complete carcinogenic activity, whereas only the fraction containing more than three-ring PAHs may act as a skin tumour initiator.
19667728
Protection against malignant conversion in SENCAR mouse skin by all trans retinoic acid: inhibition of the ras p21-processing enzyme farnesyltransferase and Ha-ras p21 membrane localization.
Many studies have shown that all trans retinoic acid (RA) exhibits significant protective effects against mouse skin tumor promotion and spontaneous as well as enhanced malignant conversion. In a recently completed study, we showed that under treatments in which papillomas on SENCAR mouse skin are induced at low and high probabilities to convert to malignant carcinomas, RA affords significant protection against both tumor promotion and subsequent malignant conversion. More than 95% of these mouse skin papillomas and carcinomas have been shown to contain point mutation at the 61 codon of Ha-ras oncogene. The ras oncogene encodes a p21 protein that, in its mutated form, transforms mammalian cells only when p21 is at the inner surface of the plasma membrane, by a series of enzymatic reactions in which the initial step is catalyzed by farnesyltransferase (FTase). In this study, we assessed whether the protective effect of RA against malignant conversion involves the inhibition of ras p21 processing in those tumors that contain the activated ras oncogene. The FTase activity and the levels of cytosolic and membrane-bound Ha-ras p21 were determined in all papillomas and carcinomas obtained from acetone- or RA-treated animals. No matter how the data were analyzed and what comparisons were considered, in all the protocols used, compared with controls, papillomas and carcinomas obtained from RA-treated groups showed significantly decreased (P < 0.01-0.001) FTase activity. Furthermore, the tissue samples from RA-treated groups in different protocols also showed significantly diminished membrane localization of Ha-ras p21, with a concomitant increase in cytosolic Ha-ras p21 levels. The analysis of these data also showed that in all the protocols used, the increased FTase activity and membrane localization of Ha-ras p21 were associated with the induction of papillomas and their subsequent malignant conversion to squamous cell carcinomas. Taken together, these results indicate a strong correlation between the inhibition of ras p21 farnesylation because of a decrease in FTase activity by RA and its protective effect against malignant conversion of papillomas to carcinomas. Based on the results of this study, it is tempting to suggest that clinical trials evaluating the preventive or therapeutic potential of retinoids may be directed more toward those clinical malignancies that are known to contain the activated ras oncogene.
20628925
Chronic kidney disease is associated with oxidative stress independent of hypertension.
BACKGROUND
Oxidative stress is implicated in the pathogenesis of chronic kidney disease (CKD) and essential hypertension (EHTN). However, the role of hypertension in causing increased oxidative stress in patients with CKD is unknown.


METHODS
We performed a case control study in patients with EHTN and those with equal blood pressure assessed by ambulatory blood pressure monitoring but with concomitant CKD. Those with diabetes mellitus and those taking renin angiotensin inhibitors were excluded. Biomarkers of oxidative stress, malondialdehyde (MDA) and protein carbonylation and total glutathione levels were measured.


RESULTS
Average (SD) 24-hour ambulatory blood pressure in 12 patients with CKD was 134 (17)/75 (16) compared to 134 (10)/80 (9) in 11 patients with EHTN (p = NS). Plasma MDA in CKD was 0.89 +/- 0.38 micromol/l compared to 0.68 +/- 0.16 micromol/l in EHTN (p = 0.07). Urinary MDA/creatinine ratio was 1.78 (0.31) in CKD vs 1.43 (0.69) micromol/g in those with EHTN (p = 0.04). Thus, lipid peroxidation was increased in urine of CKD patients. Patients with CKD had higher (1.04 (0.20) nmol) carbonyl/mg protein compared to those with EHTN (0.80 (0.21) nmol carbonyl/mg protein) (p = 0.03). Thus, protein carbonylation was increased in CKD patients. Total glutathione in CKD and EHTN patients was 6.6 (1.8) ng/ml and 7.3 (3.1) ng/ml (p = NS). There was a good correlation between biomarkers of lipid (MDA) and protein oxidation (protein carbonyls) (r = 0.6, p = 0.004).


CONCLUSIONS
Biomarkers of lipid and protein oxidation are higher in patients with CKD compared to EHTN despite similar blood pressure. Thus, nonhemodynamic factors such as inflammation and altered cellular redox state may play a greater role in the generation of oxidative stress in CKD.