Clinical-parasitological and epidemiological review of the nematode Acanthocheilonema reconditum

Acanthocheilonema (Dipetalonema) reconditum is a less pathogenic species of filaria from the superfamily Filarioidea, and which parasitizes in the subcutaneous connective tissue of dogs, hyenas and jackals. The results of epidemiological studies indicate the zoonotic potential of A. reconditum, bearing in mind it can cause infections with clinical disorders in humans. This filaria is spread globally and it is mostly described in geographical areas such as the Mediterranean Basin, the Middle East, South Africa, South America and Oceania, where it is the only or is the most common filaria that infects dogs. The prevalence and distribution of A. reconditum depend mainly on the vector population, impact of environmental factors, and lifestyle of pets and their owners. Apart from the standard parasitological techniques for differential diagnostics of filariae, more attention is being dedicated to the development of protocols that are based on the simultaneous detection of specific DNA regions in each type of individual filaria. Due to its importance for public health, effective vector control is required, as well as regular preventive examinations, reliable diagnostics and therapy for A. reconditum in dogs, and continuous cooperation between veterinary and medical surgeons

Structural insight into SUMO chain recognition and manipulation by the ubiquitin ligase RNF4

The small ubiquitin-like modifier (SUMO) can form polymeric chains that are important signals in cellular processes such as meiosis, genome maintenance and stress response. The SUMO-targeted ubiquitin ligase RNF4 engages with SUMO chains on linked substrates and catalyses their ubiquitination, which targets substrates for proteasomal degradation. Here we use a segmental labelling approach combined with solution nuclear magnetic resonance (NMR) spectroscopy and biochemical characterization to reveal how RNF4 manipulates the conformation of the SUMO chain, thereby facilitating optimal delivery of the distal SUMO domain for ubiquitin transfer

Modeling Conformational Ensembles of Slow Functional Motions in Pin1-WW

Protein-protein interactions are often mediated by flexible loops that experience conformational dynamics on the microsecond to millisecond time scales. NMR relaxation studies can map these dynamics. However, defining the network of inter-converting conformers that underlie the relaxation data remains generally challenging. Here, we combine NMR relaxation experiments with simulation to visualize networks of inter-converting conformers. We demonstrate our approach with the apo Pin1-WW domain, for which NMR has revealed conformational dynamics of a flexible loop in the millisecond range. We sample and cluster the free energy landscape using Markov State Models (MSM) with major and minor exchange states with high correlation with the NMR relaxation data and low NOE violations. These MSM are hierarchical ensembles of slowly interconverting, metastable macrostates and rapidly interconverting microstates. We found a low population state that consists primarily of holo-like conformations and is a “hub” visited by most pathways between macrostates. These results suggest that conformational equilibria between holo-like and alternative conformers pre-exist in the intrinsic dynamics of apo Pin1-WW. Analysis using MutInf, a mutual information method for quantifying correlated motions, reveals that WW dynamics not only play a role in substrate recognition, but also may help couple the substrate binding site on the WW domain to the one on the catalytic domain. Our work represents an important step towards building networks of inter-converting conformational states and is generally applicable

Structure-Based Predictive Models for Allosteric Hot Spots

In allostery, a binding event at one site in a protein modulates the behavior of a distant site. Identifying residues that relay the signal between sites remains a challenge. We have developed predictive models using support-vector machines, a widely used machine-learning method. The training data set consisted of residues classified as either hotspots or non-hotspots based on experimental characterization of point mutations from a diverse set of allosteric proteins. Each residue had an associated set of calculated features. Two sets of features were used, one consisting of dynamical, structural, network, and informatic measures, and another of structural measures defined by Daily and Gray [1]. The resulting models performed well on an independent data set consisting of hotspots and non-hotspots from five allosteric proteins. For the independent data set, our top 10 models using Feature Set 1 recalled 68–81% of known hotspots, and among total hotspot predictions, 58–67% were actual hotspots. Hence, these models have precision P = 58–67% and recall R = 68–81%. The corresponding models for Feature Set 2 had P = 55–59% and R = 81–92%. We combined the features from each set that produced models with optimal predictive performance. The top 10 models using this hybrid feature set had R = 73–81% and P = 64–71%, the best overall performance of any of the sets of models. Our methods identified hotspots in structural regions of known allosteric significance. Moreover, our predicted hotspots form a network of contiguous residues in the interior of the structures, in agreement with previous work. In conclusion, we have developed models that discriminate between known allosteric hotspots and non-hotspots with high accuracy and sensitivity. Moreover, the pattern of predicted hotspots corresponds to known functional motifs implicated in allostery, and is consistent with previous work describing sparse networks of allosterically important residues

Development of dimeric prodrug inhibitors of P-glycoprotein and ABCG2 to enhance brain penetration of antiretroviral agents

A major obstacle in eradicating the human immunodeficiency virus type 1 (HIV-1) is the development of viral reservoirs in the host\u27s cells and several anatomical organs including the brain. Brain reservoirs result from limited penetration of anti-retroviral therapeutics caused in part by efflux transporters such as P-glycoprotein (P-gp) and ABCG2 at the blood-brain barrier (BBB). Thus the development of inhibitors of P-gp and ABCG2 is a promising strategy for increasing drug penetration in order to eradicate the HIV reservoirs. We have developed two classes of dimeric prodrug inhibitors based on HIV-1 protease inhibitors (HIV-PIs) and the nucleoside reverse transcriptase inhibitors (NRTIs), abacavir and zidovudine (AZT). The first class consisted of homodimeric inhibitors of P-gp and ABCG2 which were designed to have two functions: (a) inhibit efflux by P-gp/and or ABCG2 at the BBB and (b) revert to monomer within cellular environments for HIV therapy. Many of these homodimers were found to inhibit the transporters in cell culture. Competition studies with the substrate [125I] iodoarylazidoprazosin showed that these dimers inhibit by competing with substrates for binding sites on P-gp and BCG2. Further studies with abacavir prodrug homodimers demonstrated that these compounds are potent inhibitors of P-gp in T –lymphocytes, brain endothelial cells and rat brain capillaries. In addition, the abacavir dimers inhibited HIV-1 replication in MT-2 and 12D7 T-cells due to reversion of the dimers to therapeutic abacavir in cellular reducing conditions. The second class of compounds were heterodimeric inhibitors composed of an HIV-PI and a NRTI linked by a tether. These heterodimers would function to inhibit P-gp and ABCG2, and also revert to monomers within cellular environments for combination HIV therapy. Heterodimers based on the HIV-PIs amprenavir, saquinavir and ritonavir and the NRTIs abacavir and AZT were synthesized and found to inhibit P-gp and ABCG2 in mammalian cells

Effects of cardiac rehabilitation treatment modalities in Sub-Saharan Africa: A systematic review

Purpose Although Cardiac Rehabilitation (CR) implementation models recommend delivery of any CR treatment component, Sub-Saharan Africa (SSA) constitutes only 17% of globally available CR programs. The aims of this review were to assess the benefits of employing any CR treatment modality in SSA, and evaluate if this approach should be encouraged in this resource-constrained region.MethodologyRecords were identified electronically via CINAHL, MEDLINE, Cochrane library, African journal online, PubMed, Web of science and google scholar, and grey literature was hand-searched. Articles reporting effectiveness of any CR treatment modality were included if participants had any cardiovascular disease and if the study was conducted in SSA. Quality assessment for each enrolled study was done using Downs and Black (1998) checklist and data was extracted using a modified standard tool.ResultsSearches identified 1666 records, 24 full text articles were examined and 10 were included for the review; 60%, 30% and 10% of the enrolled studies were done in South Africa, Nigeria and Benin respectively. The studies implemented exercise, psychosocial and education treatment modalities of CR, and the approach of delivery was either comprehensive or modified. Comprehensive CR and delivery of combined aerobic and resistance exercises improved physical (13%, p=0.001), social (40%, p=0.001) and mental aspects of quality of life and reduced anxiety (-12%, p<0.05) and depression (-6%, p<0.001) respectively. Comprehensive CR and aerobic training both reduced systolic blood pressure (range of mean reduction [RMR] -6 to -14mmHg), diastolic blood pressure (RMR -4 to -6mmHg) and resting heart rate (RMR -7 to -17bpm). Overall, all types of exercises showed a 1-5ml.kg-1.min-1 increase in peak oxygen consumption.ConclusionThe findings support delivery of exercise treatment modality and comprehensive delivery of CR in SSA. However, efficacy of independent implementation of education and psychosocial therapeutic components of CR remains unclear; hence the need for further investigation

A Salmonella enterica subspecies enterica serovar Choleraesuis outbreak in weaned piglets in Serbia: clinical signs, pathologic changes, and microbiologic features

Salmonella enterica subspecies enterica serovar Choleraesuis is rarely detected in Europe, but the clinical disease has been reported in wild boars. We describe here the clinical findings, pathologic changes, and microbiologic features of swine salmonellosis caused by S. enterica serovar Choleraesuis in weaned piglets in Serbia. In April 2019, on a large farrow-to-finish pig farm, increased mortality was reported in weaned piglets, marked by lethargy, anorexia, pyrexia, and respiratory distress. Gross pathology revealed dermal cyanosis, mesenteric lymphadenopathy, splenomegaly, hepatomegaly, interstitial pneumonia, and colitis. By direct culturing of lung, liver, spleen, and lymph nodes, S. enterica ser. Choleraesuis variant Kunzendorf was isolated after years of absence of the disease in pig farms in Europe. The source of this salmonellosis outbreak caused by S. enterica ser. Choleraesuis remains unknown

Stereospecific gating of functional motions in Pin1

Pin1 is a modular enzyme that accelerates the cis-trans isomerization of phosphorylated-Ser/Thr-Pro (pS/T-P) motifs found in numerous signaling proteins regulating cell growth and neuronal survival. We have used NMR to investigate the interaction of Pin1 with three related ligands that include a pS-P substrate peptide, and two pS-P substrate analogue inhibitors locked in the cis and trans conformations. Specifically, we compared the ligand binding modes and binding-induced changes in Pin1 side-chain flexibility. The cis and trans binding modes differ, and produce different mobility in Pin1. The cis-locked inhibitor and substrate produced a loss of side-chain flexibility along an internal conduit of conserved hydrophobic residues, connecting the domain interface with the isomerase active site. The trans-locked inhibitor produces a weaker conduit response. Thus, the conduit response is stereoselective. We further show interactions between the peptidyl-prolyl isomerase and Trp-Trp (WW) domains amplify the conduit response, and alter binding properties at the remote peptidyl-prolyl isomerase active site. These results suggest that specific input conformations can gate dynamic changes that support intraprotein communication. Such gating may help control the propagation of chemical signals by Pin1, and other modular signaling proteins