Purine salvage enzymes have been of significant interest in anti-Leishmanial drug development due to the parasite's critical dependence on this pathway for the supply of nucleotides in the absence of ...a de novo purine synthesis pathway. Adenylosuccinate lyase (ADSL) one of the key enzymes in this pathway is a homo-tetramer, where the active site is formed by residues from three distinct subunits. Analysis of the subunit interfaces of LdADSL, revealed a conserved Arg40 forming critical inter-subunit interactions and also involved in substrate binding. We hypothesized that mutating this residue can affect both the structural stability and activity of the enzyme. In our study, we used biochemical, biophysical, and computational simulation approaches to understand the structural and functional role of Arg40 in LdADSL. We have replaced Arg40 with an Ala and Glu using site directed mutagenesis. The mutant enzymes were similar to wild-type enzyme in secondary structure and subunit association. Thermal shift assays indicated that the mutations affected the protein stability. Both mutants showed decreased specific activities in both forward and reverse directions with significantly weakened affinities towards succinyl-adenosine monophosphate (SAMP). The mutations resulted in changes in C3 loop conformation and D3 domain rotation. Consequently, the orientation of the active site amino acid residues changed resulting in compromised activity and stability. Studies so far have majorly focused on the ADSL active site for designing drugs against it. Our work indicates that an alternative inhibitory mechanism for the enzyme can be designed by targeting the inter-subunit interface.
Display omitted
•Arg40 is located at dimeric interface of LdADSL and is also part of active site of enzyme.•LdADSL-R40A and LdADSL-R40E mutants showed reduced affinity towards the substrate.•The mutants retained the tetrameric structure but showed reduced stability.•Mutations resulted in changed orientation of active site residues and the substrate.•Arg40 is necessary for the stability and catalytic activity of LdADSL.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
During professional hygiene procedures, different instruments used may cause various damage to dental prostheses. Deplaquing and scaling with curettes and ultrasonic instruments may inadvertently ...increase the surface roughness of the material and the risk of future bacterial adhesion and/or also compromise the marginal seal of the prosthesis. Hence, the aim of this study was to assess the qualitative effects of two types of curettes and one piezoelectric instrument with a stainless-steel tip on three types of metal-free samples. After treating the samples with different instrumentations, they were analyzed using the scanning electron microscope and then underwent a qualitative microanalysis by using a spectroscopy machine. All the materials tested in this study have undergone significant changes of their superficial structure after instrumentation both with mechanical and manual instruments. Plastic curettes appeared to be less aggressive than the other instruments. Disilicate samples show a significantly lower degree of surface glazing erosion compared to the zirconia sample with all the instruments used.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
•Molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in a multiborder area of Argentina.•The prevalent staphylococcal cassette chromosome mec type was SCCmec IV.•The ...Cordobes/Chilean epidemic clone was not detected in the present MRSA collection.•ST5 was the most prevalent in colonisation, community and invasive settings.
In Latin America, methicillin-resistantStaphylococcus aureus (MRSA) is a leading cause of nosocomial infections. Limited studies have addressed the molecular epidemiology of MRSA clones in Argentina, characterised by continuous human migratory movements. The aim of this study was to describe the MRSA epidemiology, including distinct patient populations from different regions of the country.
MRSA strains were collected in epidemiological studies conducted from 2009 to 2015 in three cities (Formosa, Córdoba and Tucumán) and involving four population groups: community adult patients; hospitalised adults; hospitalised children; and healthy children (nasal colonisation). Antimicrobial susceptibility testing, SCCmec and Panton–Valentine leukocidin (PVL) typing, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed.
A total of 120 MRSA isolates were recovered with an important population diversity in the groups studied; in community adult patients, MRSA isolates corresponded to ST5, ST267 and ST1619; from hospitalised adults they were ST97, ST5, ST72, ST125, ST200, ST647, ST747, ST935 and ST2941; from hospitalised children they were ST5, ST30, ST34, ST1163 and ST1619; and from colonised children they were ST5, ST125, ST34, ST100, ST1619, ST207 and ST1163. Results of SCCmec typing showed SCCmec I, SCCmec IIIA, SCCmec IV and SCCmec ND associated or not with PVL genes.
MRSA genetic lineages have differing distribution in the three regions. The most prevalent was ST5 in colonisation, community and invasive settings. Here we describe ST34-SCCmec IV clone for the first time in the hospitalised paediatric population. These findings contribute to the understanding of epidemiological changes in recent years.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
is a nosocomial pathogen associated with drug resistance and healthcare-associated infections.
is associated with hospital-acquired infections with the ability to acquire mechanisms of resistance to ...reserve antimicrobials; its clinical behaviour has been poorly documented.
We proposed to investigate an outbreak of carbapenem-resistant
in a hospital that persisted for 4 months.
The primary aim was to evaluate the molecular characteristics and the clonal relationships among the isolates. We characterized isolates by polymerase chain reaction (PCR) and pulsed-field gel electrophoresis (PFGE). The information was integrated with clinical and epidemiological data.
Fourteen strains were disseminated in an intensive care unit and different wards at the hospital. The overall mortality was 42.8 %, and mortality attributed to infection was 21.4 %; strains showed high rates of resistance to most of the antimicrobials tested and carried
,
and
genes. PFGE analysis indicated 2 PFGE groups; 12/14 isolates were associated with subgroup A and were likely to be primarily responsible for the first isolation and subsequent dissemination. The outbreak characteristics data showed prolonged hospitalization and previous use of antibiotics as potential risk factors.
We consider that it is essential to perform phenotypic and genotypic identification of early genetic resistance mechanisms in
isolates, not only from infection sites but also from colonization, to prevent the spread of these multidrug-resistant (MDR) isolates.
A quantitative understanding of how sensory signals are transformed into motor outputs places useful constraints on brain function and helps to reveal the brain's underlying computations. We ...investigate how the nematode
responds to time-varying mechanosensory signals using a high-throughput optogenetic assay and automated behavior quantification. We find that the behavioral response is tuned to temporal properties of mechanosensory signals, such as their integral and derivative, that extend over many seconds. Mechanosensory signals, even in the same neurons, can be tailored to elicit different behavioral responses. Moreover, we find that the animal's response also depends on its behavioral context. Most dramatically, the animal ignores all tested mechanosensory stimuli during turns. Finally, we present a linear-nonlinear model that predicts the animal's behavioral response to stimulus.
The main goal of this review is to provide an updated overview of the involvement of the RNA-binding protein (RBP) HuD, encoded by the ELAVL4 gene, in nervous system development, maintenance, and ...function, and its emerging role in nervous system diseases. A particular focus is on recent studies reporting altered HuD levels, or activity, in disease models and patients. Substantial evidence suggests HuD involvement in Parkinson's disease (PD), Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS). Interestingly, while possible disease-causing mutations in the ELAVL4 gene remain elusive, a common theme in these diseases seems to be the altered regulation of HuD at multiple steps, including post-transcriptional and post-translational levels. In turn, the changed activity of HuD can have profound implications for its target transcripts, which are overly stabilized in case of HuD gain of function (as proposed in PD and ALS) or reduced in case of decreased HuD binding (as suggested by some studies in AD). Moreover, the recent discovery that HuD is a component of pathological cytoplasmic inclusion in both familial and sporadic ALS patients might help uncover the common molecular mechanisms underlying such complex diseases. We believe that deepening our understanding of the involvement of HuD in neurodegeneration could help developing new diagnostic and therapeutic tools.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
To compare optical coherence tomography angiography (OCTA) images from three different devices.
This was a prospective, observational, cross-sectional study. All eyes (n = 24) were imaged thrice each ...time with swept-source OCT (DRI OCT Triton Plus; Topcon, Tokyo, Japan), spectral-domain OCTA (AngioVue; Optovue, Fremont, CA), and SD-OCT Angioplex (Cirrus HD-OCT 5000; Carl Zeiss Meditec, Jena, Germany). Outcome measures were foveal avascular zone (FAZ) area, vessel density, spacing between large vessels (SLV), and spacing between small vessels (SSV). They were calculated using local fractal analyses and Frangi filter.
The vascular parameters showed good to excellent repeatability (intraclass coefficient > 0.8) in the three devices. The FAZ area (P = .3) and vessel density of the superficial layer (P = .8) were similar between the devices. In the deep layer, vessel density was significantly higher (P = .02) with Angio-Vue images compared to those acquired using the other devices. However, SLV was significantly higher (P < .05) and SSV was significantly lower (P < .05) on Angioplex scans compared to other devices. Vessel parameters were significantly altered in Frangi-filtered images as compared to nonfiltered images.
Vessel density showed good repeatability among the three devices, although there were differences in vessel parameters between the devices. Also, vessel parameters changed significantly after Frangi filtering. Ophthalmic Surg Lasers Imaging Retina. 2018;49:488-496..
Display omitted
•Tree saplings tolerated defoliation by bud activation.•New branch development allowed tree sapling aerial growth maintenance.•Defoliation decreased tree sampling height, diameter, ...and root growth.•Cattle grazing may retard juvenile recruitment into reproductive size classes.
Livestock rearing is increasing in savannas, so the ability of trees to regrow after consumption represents one of the critical aspects of savanna structure and functioning. Here, we identified specific traits—which may explain the mechanisms behind defoliation tolerance—in saplings of two encroacher tree species (Vachellia caven and Vachellia aroma). We carried out common garden and field experiments where manual defoliation treatments simulated the cattle grazing regime employed in the study region. At the end of the experiments, we recorded growth variables and, in the common garden experiment, root reserves concentration. In the common garden, defoliation decreased height and basal diameter growth but did not affect the aerial relative growth rate. Also, defoliation increased the number of branches per plant and decreased root relative growth rate. Starch concentration was higher or similar in defoliated plants than controls, depending on the species. In the field, defoliation decreased both species’ height and basal diameter growth. We found that tree saplings tolerated defoliation, and the mechanisms behind tolerance would be linked mainly to the axillary bud activation and not to storage reserve mobilization. Over time, these plant architectural changes might complicate cattle movement and management in these systems. From a long-term perspective, livestock rearing might retard juvenile recruitment into reproductive-size classes (e.g., adults) by reducing overall tree growth rates.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Quantitative Precipitation Estimates (QPE) from merged rain gauge and radar measurements have become widely available in the last two decades. The errors associated with these products are yet to be ...fully understood, especially in complex terrain where ground clutter and overshooting artifacts are significant and vary in space and time depending on the storm and underlying synoptic conditions. The location and timing of precipitation in addition to rainfall intensity and duration are critical to the simulation of flood response in headwater basins. This work proposes a generalizable Physics‐guided Artificial Intelligence (PAI) framework for QPE error modeling. First, QPE error climatology derived from the hydrologic Inverse Rainfall Correction (Liao & Barros, 2022, https://doi.org/10.1016/j.rse.2022.113107) to historical floods in selected headwater basins is analyzed to identify dominant precipitation regimes. Second, for each precipitation regime, a Multilayer Perceptron error prediction model is trained using event‐specific precipitation metrics at hourly scale as input, and subsequently used to predict estimation errors for various QPE products. The corrected QPE can then be used for hydrologic simulations and flood nowcasting. The PAI framework is demonstrated in the Southern Appalachian Mountains using the 57 largest floods over 2008–2017. The Probability Distribution Function of predicted precipitation errors follows a Gaussian‐like distribution but varies significantly between cold and warm season events, while the spatial distribution is inextricably connected to basin geomorphology. On average, large improvements on hourly Kling‐Gupta Efficiency from −0.5 to 0.4 are achieved, and the peak flood error is reduced by 70%, with distinctively better results for cold season events.
Key Points
Quantitative Precipitation Estimates (QPE) error modeling conditional on precipitation regime constrained by water budget closure at event‐scale in headwater basins
Automated space‐time QPE error prediction using machine learning
QPE error metrics target operational streamflow prediction skill
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We present a high-throughput optogenetic illumination system capable of simultaneous closed-loop light delivery to specified targets in populations of moving Caenorhabditis elegans. The instrument ...addresses three technical challenges: It delivers targeted illumination to specified regions of the animal's body such as its head or tail; it automatically delivers stimuli triggered upon the animal's behavior; and it achieves high throughput by targeting many animals simultaneously. The instrument was used to optogenetically probe the animal's behavioral response to competing mechanosensory stimuli in the the anterior and posterior gentle touch receptor neurons. Responses to more than 43,418 stimulus events from a range of anterior-posterior intensity combinations were measured. The animal's probability of sprinting forward in response to a mechanosensory stimulus depended on both the anterior and posterior stimulation intensity, while the probability of reversing depended primarily on the anterior stimulation intensity. We also probed the animal's response to mechanosensory stimulation during the onset of turning, a relatively rare behavioral event, by delivering stimuli automatically when the animal began to turn. Using this closed-loop approach, over 9,700 stimulus events were delivered during turning onset at a rate of 9.2 events per worm hour, a greater than 25-fold increase in throughput compared to previous investigations. These measurements validate with greater statistical power previous findings that turning acts to gate mechanosensory evoked reversals. Compared to previous approaches, the current system offers targeted optogenetic stimulation to specific body regions or behaviors with many fold increases in throughput to better constrain quantitative models of sensorimotor processing.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
