Dehydroepiandrosterone protects the microcirculation of muscle flaps from ischemia-reperfusion injury by reducing the expression of adhesion molecules

Adhesion molecules contribute to ischemia-reperfusion injury by increasing the endothelial adhesion and extravasation of leukocytes. Scientific evidence suggests that presurgical treatment with dehydroepiandrosterone may protect the microvasculature against this damage, but the exact mechanism is not known. The purpose of this study was to investigate the effects of presurgical dehydroepiandrosterone treatment on microcirculatory hemodynamic parameters and the expression of adhesion molecules in a rat cremaster muscle flap model. Twenty male rats were randomly assigned to three experimental groups. In group I (n = 5), the muscle flaps did not receive presurgical treatment. In group II (n = 6), propylene glycol (30 mg/kg), the vehicle for dehydroepiandrosterone, was injected intravenously before ischemia was induced. In group III (n = 9), dehydroepiandrosterone (30 mg/kg) was injected intravenously before ischemia was induced. All flaps were subjected to 6 hours of ischemia and 90 minutes of reperfusion. Microcirculatory variables (functional capillary density, red blood cell velocity in the main flap arteriole, and numbers of rolling, sticking, and transmigrating leukocytes), blood levels of three adhesion molecules (L-selectin, Mac-1 integrin, and CD44), and the numbers of leukocytes expressing those molecules were analyzed. Analysis of the microcirculatory parameters revealed that dehydroepiandrosterone treatment before ischemia had significant preservative effects on the red blood cell velocity and functional capillary density 30 and 90 minutes after reperfusion, compared with the control and vehicle-treated groups. Leukocyte-endothelial cell interactions were also affected by dehydroepiandrosterone treatment, as reflected by significant decreases in the numbers of sticking and transmigrating leukocytes 30 and 90 minutes after reperfusion. In dehydroepiandrosterone-treated animals, leukocytes exhibited lower levels of expression of adhesion molecules after the onset of ischemia, compared with the control groups. In this study, intravenous dehydroepiandrosterone administration reduced the activation of leukocytes and improved red blood cell velocity and capillary perfusion in the muscle flap microcirculation during ischemia-reperfusion injury. This protective effect was most likely the result of delayed expression of Mac-1 integrin, L-selectin, and CD44 molecules on leukocytes.     

Backbone dynamics measurements on leukemia inhibitory factor, a rigid four-helical bundle cytokine

The backbone dynamics of the four-helical bundle cytokine leukemia inhibitory factor (LIF) have been investigated using 15N NMR relaxation and amide proton exchange measurements on a murine-human chimera, MH35-LIF. For rapid backbone motions (on a time scale of 10 ps to 100 ns), as probed by 15N relaxation measurements, the dynamics parameters were calculated using the model-free formalism incorporating the model selection approach. The principal components of the inertia tensor of MH35-LIF, as calculated from its NMR structure, were 1:0.98:0.38. The global rotational motion of the molecule was, therefore, assumed to be axially symmetric in the analysis of its relaxation data. This yielded a diffusion anisotropy D(parallel)/D(perpendicular) of 1.31 and an effective correlation time (4D(perpendicular) + 2D(parallel))(-1) of 8.9 ns. The average values of the order parameters (S2) for the four helices, the long interhelical loops, and the N-terminus were 0.91, 0.84, and 0.65, respectively, indicating that LIF is fairly rigid in solution, except at the N-terminus. The S2 values for the long interhelical loops of MH35-LIF were higher than those of their counterparts in short-chain members of the four-helical bundle cytokine family. Residues involved in LIF receptor binding showed no consistent pattern of backbone mobilities, with S2 values ranging from 0.71 to 0.95, but residues contributing to receptor binding site III had relatively lower S2 values, implying higher amplitude motions than for the backbone of sites I and II. In the relatively slow motion regime, backbone amide exchange measurements showed that a number of amides from the helical bundle exchanged extremely slowly, persisting for several months in 2H2O at 37 degrees C. Evidence for local unfolding was considered, and correlations among various structure-related parameters and the backbone amide exchange rates were examined. Both sets of data concur in showing that LIF is one of the most rigid four-helical bundle cytokines.     

β-Carotene inhibition of aflatoxin biosynthesis amongAspergillus flavus genotypes from Illinois corn

Thirty-nineAspergillus flavus genotypes (DNA fingerprinting) isolated from corn grown in a field near Kilbourne, Illinois were evaluated for their sensitivity to β-carotene (50 μg/ml) inhibition of aflatoxin B₁ biosynthesis. Inhibition of aflatoxin was greater than 90% for 28 of the genotypes and >70% for 38 of the 39 genotypes. FiveA. flavus strains (4 fingerprint groups) isolated from molded raw peanuts, NRRL 3239, NRRL 3357, NRRL 6514, NRRL 6515 and NRRL 13135, produced greater quantities of aflatoxin than all 39 genotypes isolated from corn, and were less sensitive to β-carotene inhibition.Aspergillus flavus NRRL 3357 is commonly used as inoculum in variety trials for aflatoxin resistance. Isolate identity and sensitivity to potential inhibitors in corn can be critical in assessing corn resistance to aflatoxin.     

Mistletoes as parasites: Host specificity and speciation

Recent research on parasite evolution has highlighted the importance of host specialization in speciation, either through host-switching or cospeciation. Many parasites show common patterns of host specificity, with higher host specificity where host abundance is high and reliable, phylogenetically conservative host specificity, and formation of races on or in different host species. Recent advances in our understanding of host specificity and speciation patterns in a variety of animal parasites provides valuable insights into the evolutionary biology of mistletoes.     

Binding of the sea anemone polypeptide BDS II to the voltage-gated sodium channel.

BDS II, a 43-residue polypeptide from the sea anemone Anemonia sulcata, is reported to have both antihypertensive and antiviral activity. This polypeptide possesses a number of sequence and structural similarities to a class of cardiotonic proteins which bind to receptor site 3 of the voltage-gated sodium channel. In contrast to these cardiostimulant proteins, which produce positive inotropic effects at concentrations of 2-15 nM, BDS II produced a weak negative inotropic effect upon isolated guinea-pig atria, with doses of 90 and 180 nM depressing contractile strength by 15 and 28%, respectively. BDS II also competed with a 125-iodine labelled derivative of AP-A (a representative of the cardiostimulant proteins) bound to sodium channels in rat brain synaptosomes. The IC50 for BDS II versus AP-A was 5.2 microM. BDS II may therefore be considered an antagonist for receptor site 3 of the voltage-gated sodium channel. Structural differences between BDS II and the agonist AP-A which may give rise to their different effects on the sodium channel are considered.     

Conformational Dynamics and Antigenicity in the Disordered Malaria Antigen Merozoite Surface Protein 2

Merozoite surface protein 2 (MSP2) of Plasmodium falciparum is an abundant, intrinsically disordered protein that is GPI-anchored to the surface of the invasive blood stage of the malaria parasite. Recombinant MSP2 has been trialled as a component of a malaria vaccine, and is one of several disordered proteins that are candidates for inclusion in vaccines for malaria and other diseases. Nonetheless, little is known about the implications of protein disorder for the development of an effective antibody response. We have therefore undertaken a detailed analysis of the conformational dynamics of the two allelic forms of MSP2 (3D7 and FC27) using NMR spectroscopy. Chemical shifts and NMR relaxation data indicate that conformational and dynamic properties of the N- and C-terminal conserved regions in the two forms of MSP2 are essentially identical, but significant variation exists between and within the central variable regions. We observe a strong relationship between the conformational dynamics and the antigenicity of MSP2, as assessed with antisera to recombinant MSP2. Regions of increased conformational order in MSP2, including those in the conserved regions, are more strongly antigenic, while the most flexible regions are minimally antigenic. This suggests that modifications that increase conformational order may offer a means to tune the antigenicity of MSP2 and other disordered antigens, with implications for vaccine design.     

Kidney Function,Endothelial Activation and Atherosclerosis in Black and White Africans with Rheumatoid Arthritis

Objective

To determine whether kidney function independently relates to endothelial activation and ultrasound determined carotid atherosclerosis in black and white Africans with rheumatoid arthritis (RA).

Methods

We calculated the Jelliffe, 5 Cockcroft-Gault equations, Salazar-Corcoran, Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimated glomerular filtration rate (EGFR) equations in 233 (112 black) RA patients.

Results

The CKD-EPI eGFR was <90 ml/min/1.73m² in 49.1% and 30.6% of black and white patients, respectively (odds ratio (95% confidence interval) = 2.19 (1.28–3.75), p = 0.004). EGFRs were overall consistently associated with monocyte chemoattractant protein-1 and angiopoietin 2 concentrations in white patients, and with carotid intima-media thickness and plaque in black participants. Amongst black patients, plaque prevalence was 36.7% and the area under the curve (AUC) of the receiver operating characteristic (ROC) curve was not associated with plaque presence for the MDRD equation (p = 0.3), whereas the respective relationship was significant or borderline significant (p = 0.003 to 0.08) and of similar extent (p>0.1 for comparisons of AUC (SE)) for the other 8 equations. Based on optimal eGFR cutoff values with sensitivities and specificities ranging from 42 to 60% and 70 to 91% respectively, as determined in ROC curve analysis, a low eGFR increased the odds ratio for plaque 2.2 to 4.0 fold.

Conclusion

Reduced kidney function is independently associated with atherosclerosis and endothelial activation in black and white Africans with RA, respectively. CKD is highly prevalent in black Africans with RA. Apart from the MDRD, eGFR equations are useful in predicting carotid plaque presence, a coronary heart disease equivalent, amongst black African RA patients.     

Transcriptomic Identification of ADH1B as a Novel Candidate Gene for Obesity and Insulin Resistance in Human Adipose Tissue in Mexican Americans from the Veterans Administration Genetic Epidemiology Study (VAGES)

Type 2 diabetes (T2D) is a complex metabolic disease that is more prevalent in ethnic groups such as Mexican Americans, and is strongly associated with the risk factors obesity and insulin resistance. The goal of this study was to perform whole genome gene expression profiling in adipose tissue to detect common patterns of gene regulation associated with obesity and insulin resistance. We used phenotypic and genotypic data from 308 Mexican American participants from the Veterans Administration Genetic Epidemiology Study (VAGES). Basal fasting RNA was extracted from adipose tissue biopsies from a subset of 75 unrelated individuals, and gene expression data generated on the Illumina BeadArray platform. The number of gene probes with significant expression above baseline was approximately 31,000. We performed multiple regression analysis of all probes with 15 metabolic traits. Adipose tissue had 3,012 genes significantly associated with the traits of interest (false discovery rate, FDR ≤ 0.05). The significance of gene expression changes was used to select 52 genes with significant (FDR ≤ 10^-4) gene expression changes across multiple traits. Gene sets/Pathways analysis identified one gene, alcohol dehydrogenase 1B (ADH1B) that was significantly enriched (P < 10^-60) as a prime candidate for involvement in multiple relevant metabolic pathways. Illumina BeadChip derived ADH1B expression data was consistent with quantitative real time PCR data. We observed significant inverse correlations with waist circumference (2.8 x 10^-9), BMI (5.4 x 10^-6), and fasting plasma insulin (P < 0.001). These findings are consistent with a central role for ADH1B in obesity and insulin resistance and provide evidence for a novel genetic regulatory mechanism for human metabolic diseases related to these traits.