Mapping the lethal factor and edema factor binding sites on oligomeric anthrax protective antigen

Assembly of anthrax toxin complexes at the mammalian cell surface involves competitive binding of the edema factor (EF) and lethal factor (LF) to heptameric oligomers and lower order intermediates of PA(63), the activated carboxyl-terminal 63-kDa fragment of protective antigen (PA). We used sequence differences between PA(63) and homologous PA-like proteins to delineate a region within domain 1' of PA that may represent the binding site for these ligands. Substitution of alanine for any of seven residues in or near this region (R178, K197, R200, P205, I207, I210, and K214) strongly inhibited ligand binding. Selected mutations from this set were introduced into two oligomerization-deficient PA mutants, and the mutants were used in various combinations to map the single ligand site within dimeric PA(63). The site was found to span the interface between two adjacent subunits, explaining the dependence of ligand binding on PA oligomerization. The locations of residues comprising the site suggest that a single ligand molecule sterically occludes two adjacent sites, consistent with the finding that the PA(63) heptamer binds a maximum of three ligand molecules. These results elucidate the process by which the components of anthrax toxin, and perhaps other binary bacterial toxins, assemble into toxic complexes.     

Inhibitor design by wrapping packing defects in HIV-1 proteins

Two viral proteins, HIV-1 protease and HIV-1 integrase, have been targeted for inhibitor design to prevent assembly and maturation of HIV-1 virions. The enzymatic mechanism of these proteins involves side-chain groups that serve as general acids or bases. Furthermore, catalytic activity requires that water be removed from the microenvironment surrounding the chemical reaction site or be constrained to serve as an activated nucleophile. Here, we identify previously unrecognized structural features that promote water removal from polar catalytic regions. Packing defects in the form of hydrogen bonds that are insufficiently dehydrated intramolecularly, named "dehydrons," are strategically placed in the structure to induce an anhydrous enzymatic pathway. Dehydrons become electrostatically enhanced and stabilized upon further desolvation. Thus, packing defects act synergistically with the polar active groups to enhance the enzymatic electrostatics. However, because dehydrons are sticky, they constitute targets for inhibitor design. We noticed that inhibitors attach to polar surfaces by further desolvating dehydrons, thus blocking the active sites or the sites involved in harnessing the substrate. The dehydrons are thus required for functional reasons, making them suitable targets. The differences in success when targeting HIV-1 protease, feline immunodeficiency virus protease, and HIV-1 integrase are rationalized in terms of the dehydron distribution, revealing possible improvements in the targeting strategy. Principles of design optimization are proposed to create an inhibitor that can be neutralized only at the expense of the loss of catalytic function. The possibility of using drugs that wrap dehydrons to block protein-protein associations is also discussed.     

Effects of Ethanol on Mature Offspring of Mice Given Ethanol during Pregnancy

Male offspring of mice maintained on isocaloric liquid diets containing either 20% ethanol or sucrose derived calories during pregnancy were tested on their ability to discriminate different ethanol doses as adults. They were trained to lever-press for a food reward on each of two levers in an operant chamber, and were then maintained on an FR20 reinforcement schedule. After response rates stabilized, ethanol discrimination training was initiated by reinforcing only responses made on the drug appropriate-lever after i.p. injections of ethanol (1.0 g/kg) or water. After learning to discriminate the 1.0 g dose, the animals' ability to discriminate doses of 0.25, 0.50, 0.75, 1.0, and 1.5 g/kg was assessed by determining the percentage of responses made on the drug lever during a 2-min test period. Compared to sucrose controls, mice exposed to alcohol in utero learned the lever response more slowly and were less responsive to injected ethanol as evidenced by a reduced effect of the drug on response rates and by a reduction in their ability to discriminate the presence of injected ethanol. The results indicate that prenatal ethanol exposure can have long term consequences which reduce the effects of ethanol in fully mature animals.     

Cadmium specific proteomic responses of a highly resistant Pseudomonas aeruginosa san ai

Pseudomonas aeruginosa san ai is a promising candidate for bioremediation of cadmium pollution, as it resists a high concentration of up to 7.2 mM of cadmium. Leaving biomass of P. aeruginosa san ai exposed to cadmium has a large biosorption potential, implying its capacity to extract heavy metal from contaminated medium. In the present study, we investigated tolerance and accumulation of cadmium on protein level by shotgun proteomics approach based on liquid chromatography and tandem mass spectrometry coupled with bioinformatics to identify proteins. Size exclusion chromatography was used for protein prefractionation to preserve native forms of metalloproteins and protein complexes. Using this approach a total of 60 proteins were observed as up-regulated in cadmium-amended culture. Almost a third of the total numbers of up-regulated were metalloproteins. Particularly interesting are denitrification proteins which are over expressed but not active, suggesting their protective role in conditions of heavy metal exposure. P. aeruginosa san ai developed a complex mechanism to adapt to cadmium, based on: extracellular biosorption, bioaccumulation, the formation of biofilm, controlled siderophore production, enhanced respiration and modified protein profile. An increased abundance of proteins involved in: cell energy metabolism, including denitrification proteins; amino acid metabolism; cell motility and posttranslational modifications, primarily based on thiol-disulfide exchange, were observed. Enhanced oxygen consumption of biomass in cadmium-amended culture versus control was found. Our results signify that P. aeruginosa san ai is naturally well equipped to overcome and survive high doses of cadmium and, as such, has a great potential for application in bioremediation of cadmium polluted sites.

When exposed to cadmium a highly resistant strain P. aeruginosa san ai responds by an increased metalloprotein expression (particularly denitrification proteins), an enhanced respiration, and a pronounced thiol-disulfide protein modifications.     

An Evaluation of the Effects of Antecedent Exercise Type on Stereotypic Behaviors

This study examined the effects of two types of physical activities on stereotypic behaviors (SBs) and task engagement of young children with autism spectrum disorder. Locomotor activities and object manipulation activities were applied to three preschoolers with autism spectrum disorder. A multi-element design with a three-component test sequence (Morrison et al. Journal of Applied Behavior Analysis, 44, 523–541, 2011) was used to identify changes in SBs and task engagement in the following three consecutive 5-min phases: pre-physical activity (pre-PA), physical activity (PA), and post-physical activity (post-PA). For the locomotor activity condition, all participants engaged in less SBs in post-PA compared to pre-PA, while increased SBs were observed in post-PA compared to pre-PA for the object manipulation activity condition. Positive effects of locomotor activities on task engagement were found, but the effects were clear to only one of the three participants.     

Bone mineral density in primary care patients related to serum calcium concentrations: a longitudinal cohort study from Sweden

Objective: Elevated calcium concentration is a commonly used measure in screening analyses for primary hyperparathyroidism (pHPT) and cancer. Low bone mineral density (BMD) and osteoporosis are common features of pHPT and strengthen the indication for parathyroidectomy. It is not known whether an elevated calcium concentration could be a marker of low BMD in suspected pHPT patients with a normal parathyroid hormone concentration.

Purpose: To study if low BMD and osteoporosis are more common after ten years in patients with elevated compared with normal calcium concentrations at baseline.

Design: Prospective case control study.

Setting: Primary care, southern Sweden.

Subjects: One hundred twenty-seven patients (28 men) with baseline elevated, and 254 patients (56 men) with baseline normal calcium concentrations, mean age 61 years, were recruited. After ten years, 77% of those still alive (74 with elevated and 154 with normal calcium concentrations at baseline) participated in a dual energy x-ray absorptiometry measurement for BMD assessment and analysis of calcium and parathyroid hormone concentrations.

Main outcome measures: Association between elevated and normal calcium concentration at base-line and BMD at follow-up. Correlation between calcium and parathyroid hormone concentrations and BMD at follow-up.

Results: A larger proportion of the patients with elevated baseline calcium concentrations who participated in the follow-up had osteoporosis (p value?=?0.036), compared with the patients with normal concentrations. In contrast, no correlation was found between calcium or parathyroid hormone concentrations and BMD at follow-up.

Conclusions: In this study, patients with elevated calcium concentrations at baseline had osteoporosis ten years later more often than controls (45% vs. 29%), which highlights the importance of examining these patients further using absorptiometry, even when their parathyroid hormone level is normal.

• Key Points

• Osteoporosis is common, difficult to detect and usually untreated. It is not known whether elevated calcium concentrations, irrespective of the PTH level, could be a marker of low bone mineral density.

• No correlation was found between calcium or parathyroid hormone concentrations and bone mineral density at follow-up.

• In this study, patients with elevated calcium concentrations at baseline had osteoporosis ten years later more often than controls (45% vs. 29%).

     

Mortality outcomes based on ED qSOFA score and HIV status in a developing low income country

Objective

To evaluate the utility of the quick Sepsis-related Organ Failure Assessment (qSOFA) score to predict risks for emergency department (ED) and hospital mortality among patients in a sub-Saharan Africa (SSA) setting.

Phytomedicines in Acute Rhinosinusitis: A Prospective,Non-interventional Parallel-Group Trial

Introduction

The objective of this prospective, multicenter, parallel-group, non-interventional clinical trial (NIT) was to characterize the effectiveness of a treatment with the phytomedicines ELOM-080 and BNO 1016 in patients with acute rhinosinusitis (ARS).

Methods

A total of 228 patients suffering from ARS took part in this NIT and were treated for a maximum of 14 days with either BNO 1016 or ELOM-080. Focus was on improvement of rhinosinusitis-associated pain/discomfort and nasal congestion in real-life conditions of primary care setting, as assessed by numeric and verbal rating scale, and five-point Likert scale.

Results

The course of the key ARS symptom facial pain demonstrated a faster recovery in patients with ELOM-080, when compared to BNO 1016. ELOM-080 tended to be superior for several ancillary criteria and induced significantly higher patient satisfaction with regard to the improvement of feeling of general illness. Physicians assessed both products to be very effective and well tolerated. Adverse drug reactions classified as gastrointestinal disorders occurred in both groups to a comparable extent.

Conclusion

This trial demonstrated comparable effectiveness of a therapy of ARS with the phytomedicines ELOM-080 and BNO 1016, although the treatment with ELOM-080 resulted in a more rapid and more complete recovery in ARS key symptoms and tended to be superior for several ancillary criteria. Both treatments were well tolerated.

Trial registration number

NIS-6471.

Funding

G. Pohl-Boskamp GmbH & Co. KG.