Kinetic evidence for the PsaE-dependent transient ternary complex photosystem I/Ferredoxin/Ferredoxin:NADP(+) reductase in a cyanobacterium.

A mutant of Synechocystis PCC 6803, deficient in psaE, assembles photosystem I reaction centers without the PsaE subunit. Under conditions of acceptor-side rate-limited photoreduction assays in vitro (with 15 microM plastocyanin included), using 100 nM ferredoxin:NADP(+) reductase (FNR) and either Synechocystis flavodoxin or spinach ferredoxin, lower rates of NADP(+) photoreduction were measured when PsaE-deficient membranes were used, as compared to the wild type. This effect of the psaE mutation proved to be due to a decrease of the apparent affinity of the photoreduction assay system for the reductase. In the psaE mutant, the relative petH (encoding FNR) expression level was found to be significantly increased, providing a possible explanation for the lack of a phenotype (i.e., a decrease in growth rate) that was expected from the lower rate of linear electron transport in the mutant. A kinetic model was constructed in order to simulate the electron transfer from reduced plastocyanin to NADP(+), and test for possible causes for the observed change in affinity for FNR. The numerical simulations predict that the altered reduction kinetics of ferredoxin, determined for the psaE mutant [Barth, P., et al., (1998) Biochemistry 37, 16233-16241], do not significantly influence the rate of linear electron transport to NADP(+). Rather, a change in the dissociation constant of ferredoxin for FNR does affect the saturation profile for FNR. We therefore propose that the PsaE-dependent transient ternary complex PSI/ferredoxin/FNR is formed during linear electron transport. Using the yeast two-hybrid system, however, no direct interaction could be demonstrated in vivo between FNR and PsaE fusion proteins.     

Trends in Expanded-Spectrum Cephalosporin-Resistant Escherichia coli and Klebsiella pneumoniae among Dutch Clinical Isolates,from 2008 to 2012

We investigated time trends in extended-spectrum cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae isolates from different patient settings in The Netherlands from 2008–2012. E. coli and K. pneumoniae isolates from blood and urine samples of patients > = 18 years were selected from the Dutch Infectious Disease Surveillance System-Antimicrobial Resistance (ISIS-AR) database. We used multivariable Poisson regression to study the rate per year of blood stream infections by susceptible and resistant isolates, and generalized estimating equation (GEE) log-binomial regression for trends in the proportion of extended-spectrum cephalosporin-resistant isolates. Susceptibility data of 197,513 E. coli and 38,244 K. pneumoniae isolates were included. The proportion of extended-spectrum cephalosporin-resistant E. coli and K. pneumoniae isolates from urine and blood samples increased in all patient settings, except for K. pneumoniae isolates from patients admitted to intensive care units. For K. pneumoniae, there was a different time trend between various patient groups (p<0.01), with a significantly higher increase in extended-spectrum cephalosporin-resistant isolates from patients attending a general practitioner than in isolates from hospitalized patients. For E. coli, the increasing time trends did not differ among different patient groups. This nationwide study shows a general increase in extended-spectrum cephalosporin-resistant E. coli and K. pneumoniae isolates. However, differences in trends between E. coli en K. pneumoniae underline the importance of E. coli as a community-pathogen and its subsequent influence on hospital resistance level, while for K. pneumoniae the level of resistance within the hospital seems less influenced by the resistance trends in the community.     

Patronage in a Holy Place: Preliminary research notes on a ‘parallel structure’ in a Yugoslav pilgrimage centre*

Eric Wolf has argued that the study of patron‐client relations and other ‘parallel structures’ may be useful for furthering our understanding of complex societies. As for political patronage, Wolfs suggestion has been taken to heart. As far as religion is concerned, his suggestion has barely met with any response at all. Data obtained from a Yugoslav peasant community seem to indicate that Wolf s proposition is applicable to the religious field as well. In Medjugorje, a pilgrimage centre in Bosnia‐Hercegovina, a patronage network has evolved around a small group of young local seers. The relations with the ‘official’, clergy‐run Marian devotion are rather strained. This article explores the dynamics of that parallel structure of the institutional Church, and discusses if and in what respects this visionary‐centered patronage network differs from patron‐client configurations in the political field.     

CT Coronary Angiography Is Feasible for the Assessment of Coronary Artery Disease in Chronic Dialysis Patients,Despite High Average Calcium Scores

Purpose

Significant obstructive coronary artery disease (CAD) is common in asymptomatic dialysis patients. Identifying these high risk patients is warranted and may improve the prognosis of this vulnerable patient group. Routine catheterization of incident dialysis patients has been proposed, but is considered too invasive. CT-angiography may therefore be more appropriate. However, extensive coronary calcification, often present in this patient group, might hamper adequate lumen evaluation. The objective of this study was to assess the feasibility of CT-angiography in this patient group.

Methods

For this analysis all patients currently participating in the ICD2 trial (ISRCTN20479861), with no history of PCI or CABG were included. The major epicardial vessels were evaluated on a segment basis (segment 1–3, 5–8, 11 and 13) by a team consisting of an interventional and an imaging specialist. Segments were scored as not significant, significant and not interpretable.

Results

A total of 70 dialysis patients, with a mean age of 66±8 yrs and predominantly male (70%) were included. The median calcium score was 623 [79, 1619].Over 90% of the analyzed segments were considered interpretable. The incidence of significant CAD on CT was 43% and was associated with cardiovascular events during follow-up. The incidence of cardiovascular events after 2-years follow-up: 36% vs. 0% in patients with no significant CAD (p<0.01).

Conclusion

Despite the high calcium scores CT-angiography is feasible for the evaluation of the extent of CAD in dialysis patients. Moreover the presence of significant CAD on CT was associated with events during follow-up.     

Reclassification of aortic stenosis by fusion of echocardiography and computed tomography in low-gradient aortic stenosis

Netherlands Heart Journal - The integration of computed tomography (CT)-derived left ventricular outflow tract area into the echocardiography-derived continuity equation results in the...     

Identification and localization of bound internal water in the solution structure of interleukin 1 beta by heteronuclear three-dimensional 1H rotating-frame Overhauser 15N-1H multiple quantum coherence NMR spectroscopy

The presence and location of bound internal water molecules in the solution structure of interleukin 1 beta have been investigated by means of three-dimensional 1H rotating-frame Overhauser 1H-15N multiple quantum coherence spectroscopy (ROESY-HMQC). In this experiment through-space rotating-frame Overhauser (ROE) interactions between NH protons and bound water separated by less than or equal to 3.5 A are clearly distinguished from chemical exchange effects, as the cross-peaks for these two processes are of opposite sign. The identification of ROEs between NH protons and water is rendered simple by spreading out the spectrum into a third dimension according to the 15N chemical shift of the directly bonded nitrogen atoms. By this means, the problems that prevent, in all but a very few limited cases, the interpretation, identification, and assignment of ROE peaks between NH protons and water in a 2D 1H-1H ROESY spectrum of a large protein such as interleukin 1 beta, namely, extensive NH chemical shift degeneracy and ROE peaks obscured by much stronger chemical exchange peaks, are completely circumvented. We demonstrate the existence of 15 NH protons that are close to bound water molecules. From an examination of the crystal structure of interleukin 1 beta [Finzel, B. C., Clancy, L. L., Holland, D. R., Muchmore, S. W., Watenpaugh, K. D., & Einspahr, H. M. (1989) J. Mol. Biol. 209, 779-791], the results can be attributed to 11 water molecules that are involved in interactions bridging hydrogen-bonding interactions with backbone amide and carbonyl groups which stabilize the 3-fold pseudosymmetric topology of interleukin 1 beta and thus constitute an integral part of the protein structure in solution.     

Imaging in cardiac resynchronisation therapy

A substantial number of heart failure (HF) patients do not respond after cardiac resynchronisation therapy (CRT). Recent studies observed that assessment of intraventricular (LV) dyssynchrony may allow identification of potential responders to CRT. In addition, presence of scar tissue and venous anatomy may play a role in the selection of candidates. In this review, an extensive overview of the available LV dyssynchrony measurements is provided using different echocardiographic modalities. In addition, the value of other noninvasive techniques such as magnetic resonance imaging, nuclear imaging and computed tomography for the selection of potential candidates for CRT will be discussed. (Neth Heart J 2008;16(suppl 1):S36-S40.)     

Intramyocellular lipid content in human skeletal muscle

Fat can be stored not only in adipose tissue but also in other tissues such as skeletal muscle. Fat droplets accumulated in skeletal muscle [intramyocellular lipids (IMCLs)] can be quantified by different methods, all with advantages and drawbacks. Here, we briefly review IMCL quantification methods that use biopsy specimens (biochemical quantification, electron microscopy, and histochemistry) and non-invasive alternatives (magnetic resonance spectroscopy, magnetic resonance imaging, and computed tomography). Regarding the physiological role, it has been suggested that IMCL serves as an intracellular source of energy during exercise. Indeed, IMCL content decreases during prolonged submaximal exercise, and analogously to glycogen, IMCL content is increased in the trained state. In addition, IMCL content is highest in oxidative, type 1 muscle fibers. Together, this, indeed, suggests that the IMCL content is increased in the trained state to optimally match fat oxidative capacity and that it serves as readily available fuel. However, elevation of plasma fatty acid levels or dietary fat content also increases IMCL content, suggesting that skeletal muscle also stores fat simply if the availability of fatty acids is high. Under these conditions, the uptake into skeletal muscle may have negative consequences on insulin sensitivity. Besides the evaluation of the various methods to quantify IMCLs, this perspective describes IMCLs as valuable energy stores during prolonged exercise, which, however, in the absence of regular physical activity and with overconsumption of fat, can have detrimental effects on muscular insulin sensitivity.