Alpha-synuclein and RNA viruses: Exploring the neuronal nexus.

Alpha-synuclein (α-syn), known for its pivotal role in Parkinson's disease, has recently emerged as a significant player in neurotropic RNA virus infections. Upregulation of α-syn in various viral infections has been found to impact neuroprotective functions by regulating neurotransmitter synthesis, vesicle trafficking, and synaptic vesicle recycling. This review focuses on the multifaceted role of α-syn in controlling viral replication by modulating chemoattractant properties towards microglial cells, virus-induced ER stress signaling, anti-oxidative proteins expression. Furthermore, the text underlines the α-syn-mediated regulation of interferon-stimulated genes. The review may help suggest potential therapeutic avenues for mitigating the impact of RNA viruses on the central nervous system by exploiting α-syn neuroprotective biology.

Peripheral blood quantitation of CD26 positive leukemic stem cells as a predictor of tyrosine kinase inhibitor response in chronic myeloid leukemia.

INTRODUCTION: Leukemic stem cells (LSCs) are the transcriptionally low/silent cells which are resistant to the tyrosine kinase inhibitor. These have been found to play a pivotal role in disease relapse in chronic myeloid leukemia (CML) cases. The present study evaluated the correlation of absolute CML-LSC count in the peripheral blood (PB) at diagnosis and achievement of major molecular response (MMR) at 12 months in patients of CML-CP. METHODS: This was a prospective, observational, non-interventional single center study including newly diagnosed adult (>18 yrs) CML-CP patients. Absolute CD26 + CML-LSC quantification was done by multiparametric flow cytometry. Patients were treated with Imatinib treatment and subsequently monitored at 3-month intervals for BCR::ABL transcript levels. MMR was defined as a BCR::ABL1 transcript level of less than 0.1% on international scale. RESULTS: A total of 89 patients were enrolled in the study out of which 40.5% achieved MMR at 12 months. There was a significant difference in the median absolute CML-LSC count of the patients who achieved MMR at 12 months as compared to those who did not (58.5 vs 368.1 cells/µL; p value <0.001). Using a ROC analysis, a count of <165.69 CML LSC/µL was identified to have a sensitivity of 83.8% and specificity of 72.4%, in predicting the MMR at 12 months. CONCLUSION: Absolute CML-LSC count at diagnosis in the PB predicts the MMR achievement at 12 months. An absolute count of less than 165 cells/µL is highly predictive of achieving MMR at 12 months.

Interfacial properties of α-synuclein's Parkinsonian variants.

Human alpha-synuclein (αS) is associated with the occurrence of Parkinson's disease. In the past decade, six autosomally dominant mutations have been identified in αS (SNCA) gene that translate into A30P, E46K, H50Q, G51D, A53E, and A53T mutations in the protein. These mutations alter the electrostatics and hydrophobicity of a cardinal region of the protein. A comprehensive comparison of interfacial properties of these Parkinsonian αS variants is crucial to understand their membrane dynamics. Here, we investigated the interfacial activity of these αS variants at air-aqueous interface. All the αS variants were found to possess comparable surface activity of ∼20-22 mN/m. Compression/expansion isotherms reveal a very distinct behaviour of the A30P variant compared to others. The Blodgett-deposited films were analysed using CD and LD spectroscopy as well as the atomic force microscopy. All the variants adopted predominantly α-helical conformation in these films. Atomic force microscopy of the Langmuir-Blodgett films revealed self-assembly at the interface. The lipid-penetration activity was also investigated using zwitterionic and negatively charged lipid monolayers.

Management of Maxillofacial Trauma in Road Traffic Accident (RTA) at Tertiary Care Center.

Road traffic accidents (RTA) are the major cause of maxillofacial injuries (MFIs) in developing countries (Akama et al. 2007). Road traffic accidents were reported to be the 9th most common cause of death and morbidity in the world and are expected to rise to 3rd position by 2020 (Peden et al. 2002). Maxillofacial injuries remain a serious clinical problem because of the involvement of complex anatomic region. Facial fractures occur most commonly in males in the third decade of life (Motamedi et al. 2014). The goal of treatment in facial fractures is to achieve anatomic reduction and restore function while increasing patient comfort and making postoperative care easier (Lachner et al. 1991). The aim of the study was to evaluate the cases of Maxillofacial injuries with the existing literature on its different presentation and management. An observational study was done from the patients of RTA with Maxillofacial injuries in ENT department and trauma centre of Sir T General hospital and Government Medical College, Bhavnagar for a period of 2 year. A total of 315 patients were included. Males are more commonly affected than females. The main etiological factor for RTA was motorcycle accidents. The trend of MFIs especially due to MCAs was on the rise after the age of 20 year. Anatomically the lower 1/3 section of the face was the most affected. Mandibular fractures were most common isolated fracture in MFIs. Open reduction and internal fixation (ORIF) by plating and screw was the treatment of choice for displaced, comminuted and multiple fractures of face. Facial trauma remains a major source of injury in all parts of the world. Its management involves many disciplines in the hospital setting, but knowledge of occlusion, the masticatory apparatus and anatomy is important for the best outcomes. This study was an analysis of demographic variables and outcome of the management adopted in patients presented to our department.

Inhibition of huntingtin aggregation by its N-terminal 17-residue peptide and its analogs.

The N-terminal 17-residue stretch of huntingtin (httN17) folds into an amphipathic α-helix. The httN17-harboring polyQ peptides form oligomers that are mediated via the assembly of the httN17 α-helices. The oligomerization results in higher local concentration of the polyglutamine (polyQ) region, thereby facilitating amyloid formation. The httN17 co-assembles with the httN17-harbouring polyQ peptides, thereby reducing the local polyQ concentration, and consequently inhibiting aggregation. This study presents the aggregation inhibition of the exon I region of pathogenic huntingtin by httN17 and its analogs. The C-terminal amidation of httN17 is found to be essential for activity. The httN17 peptides with free amino terminus and the acetylated amino terminus possess comparable activity. The httN17 analog, wherein the Leu7 and Ala10 are substituted with 2-aminoisobutyric acid residues, exhibits significantly higher activity than the native httN17.

Polymyxin B accelerates the α-synuclein aggregation.

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the loss of dopaminergic neurons. It is characterised by the deposition of insoluble α-synuclein aggregates in the brain. Constipation is a common PD-associated condition, and the treatment of constipation with certain antibiotics seem to improve the PD symptoms. Polymyxin B, a last resort drug in treating the life-threatening Gram-negative bacterial infections, is one such antibiotic. The administration of polymyxin B in PD patients is known to alleviate the movement disorder symptoms; the mechanism of action, however, remains unclear. We, therefore, wondered if polymyxin B could modulate the aggregation of α-synuclein. We find that the polymyxin B catalyses the aggregation of α-synuclein into amyloid fibrils. At equimolar polymyxin B concentration, the lag phase was reduced to around one-third of that in the absence of polymyxin B.

N-terminal acetylation does not alter α-synuclein's interfacial properties.

Alpha-synuclein (αS) is a membrane-binding protein found predominantly in neurons and erythrocytes. The protein remains unordered in aqueous solutions but folds into an α-helical structure when bound to membranes. Besides, it gets deposited as ß-sheet rich aggregates in diseases known as synucleinopathies. The native αS has been reported to be acetylated at the N-terminus. Here, we compare the interfacial properties of the N-terminal acetylated αS (Ac-αS) with non-acetylated αS (NH2-αS) at the air-water interface. Both the protein forms are highly surface-active, with surface pressure reaching up to ~30 mN/m upon compression. The pressure-area isotherms obtained from the repeated compression-expansion cycles display large hysteresis suggesting self-assembly at higher surface pressures. The expansion isotherm is characterized by a rapid decrease in surface pressure followed by a slower transition phase starting around 15-17 mN/m. These data suggest that the compressed monolayer breaks into small clusters upon expansion, followed by these clusters' loosening. The circular dichroism spectroscopic analysis of the Blodgett-deposited films suggests the protein to be in largely α-helical conformation. The linear dichroism investigations suggest the protein to be anisotropically deposited. Blodgett deposition of the Langmuir films, therefore, is a rather simple method for preparing oriented monolayers of surface-active macromolecules.

Amyloids and their untapped potential as hydrogelators.

Amyloid fibrils are cross-ß-sheet-rich fibrous aggregates. They were originally identified as disease-associated protein/peptide deposits. The cross-ß motif was consequently labelled as an alien and pathogenic fold. Subsequent research revealed that the fibrillar aggregates were benign, and the cytotoxicity in the amyloid diseases was attributed to the pre-fibrillar structures. Research in the past two decades has identified the native functional amyloids in organisms ranging from bacteria to human. The amyloid-like fibrils, therefore, are not necessarily pathogenic, and the cross-ß motif is very much native. This premise makes way for the amyloids to be used as biocompatible materials. Many naturally occurring amyloidogenic proteins/peptides or their fragments have been reported in the literature to form hydrogels. Hydrogels constitute one of the most interesting classes of soft materials that find application in diverse fields such as environmental, electronic, and biomedical engineering. Applications of hydrogels in medicine are particularly extensive. Among various classes of peptides that form hydrogels, the potential of amyloids is largely untapped. In this review, we have attempted to compile the literature on amyloid hydrogels and discuss their potential applications.

The ß-turn-supporting motif in the polyglutamine binding peptide QBP1 is essential for inhibiting huntingtin aggregation.

Aggregation of polyglutamine proteins is a hallmark of several neurodegenerative diseases. The 11-residue polyglutamine binding peptide Ac-SNWKWWPGIFD-am, known as QBP1, inhibits polyglutamine aggregation. Besides, a minimal 8-residue stretch in the QBP1 peptide (Ac-WKWWPGIF-am) is reported in the literature to retain this activity. Both peptides harbor a Pro-Gly dipeptide motif, a feature characteristic of potential ß-turn regions. Here, we investigated whether the presence of this ß-turn motif is necessary for the inhibition of huntingtin aggregation, a polyglutamine protein implicated in Huntington's disease. Using single amino acid substitutions to generate analogs that could support, introduce, or eliminate the ß-turn, we show that the turn-supporting motif is essential for QBP1-mediated inhibition of huntingtin aggregation.

Modelling past and future peatland carbon dynamics across the pan-Arctic.

The majority of northern peatlands were initiated during the Holocene. Owing to their mass imbalance, they have sequestered huge amounts of carbon in terrestrial ecosystems. Although recent syntheses have filled some knowledge gaps, the extent and remoteness of many peatlands pose challenges to developing reliable regional carbon accumulation estimates from observations. In this work, we employed an individual- and patch-based dynamic global vegetation model (LPJ-GUESS) with peatland and permafrost functionality to quantify long-term carbon accumulation rates in northern peatlands and to assess the effects of historical and projected future climate change on peatland carbon balance. We combined published datasets of peat basal age to form an up-to-date peat inception surface for the pan-Arctic region which we then used to constrain the model. We divided our analysis into two parts, with a focus both on the carbon accumulation changes detected within the observed peatland boundary and at pan-Arctic scale under two contrasting warming scenarios (representative concentration pathway-RCP8.5 and RCP2.6). We found that peatlands continue to act as carbon sinks under both warming scenarios, but their sink capacity will be substantially reduced under the high-warming (RCP8.5) scenario after 2050. Areas where peat production was initially hampered by permafrost and low productivity were found to accumulate more carbon because of the initial warming and moisture-rich environment due to permafrost thaw, higher precipitation and elevated CO2 levels. On the other hand, we project that areas which will experience reduced precipitation rates and those without permafrost will lose more carbon in the near future, particularly peatlands located in the European region and between 45 and 55°N latitude. Overall, we found that rapid global warming could reduce the carbon sink capacity of the northern peatlands in the coming decades.

Interaction of cavin-1/PTRF leucine zipper domain 2 and its congenital generalized lipodystrophy mutant with model membranes.

The organization of caveolae ultrastructures in the plasma membrane and the functions they dictate are mediated by membrane-embedded caveolins (caveolin-1, 2, 3) and peripherally attached cavins (cavin-1, 2, 3, 4). Mutations in caveolin and cavin genes are associated with a variety of human diseases. Cavin-1/PTRF mutations are known to contribute to several human pathologies, including muscular dystrophy and congenital generalized lipodystrophy (CGL). In the present study, we investigated the membrane interaction of the second leucine zipper domain (LZD2) of cavin-1 and the analogous peptide stretch in its CGL frameshift mutant (p.Glu176Argfs). The fluorescence data from the Trp-tagged peptides suggest binding of both wild-type and mutant peptide with negatively-charged membranes. The mutant peptide displayed a rather enhanced interaction compared to the wild-type peptide. In addition, the mutant peptide displayed appreciable binding to the lipid raft-mimicking cholesterol/sphingomyelin-rich vesicles as well. The alteration in the dynamics of peptide-lipid interaction is attributed to increased charge and hydrophilicity of the mutant peptides. Overall, these results suggest that the frameshift mutation in cavin-1/PTRF (p.Glu176Argfs) imparts high membrane-binding propensity to the region corresponding to LZD2, which is hitherto unknown to interact with membranes. Such interaction in the disease condition, in turn, could either alter the native membrane interaction dynamics of cavin-1/PTRF or possibly result in interaction with non-target membranes.

Water-Alcohol Bigels from Fatty Acylated Dipeptides.

Peptide-based gels are emerging as an interesting class of biocompatible soft materials. 9-Fluorenylmethoxycarbonyl-protected amino acids and short peptides have gained considerable attention as promising gelators. Peptide amphiphiles, wherein an alkyl chain is appended to a polar peptidic moiety, are another important class of peptide-based gelators. Here, we report the alcohol/water bigels formed by the rather simple fatty acylated dipeptides wherein the peptidic moiety is made up of hydrophobic amino acids, viz., Val, Ile, and Leu. Lauroyl, myristoyl, and palmitoyl were investigated as the N-terminal fatty acyl groups. None of the lauroylated peptides caused gelation of methanol/water and ethanol/water mixtures up to 2 wt % peptide concentration. Eight out of the 27 peptides resulted in distinct bigels. The gels are composed of fibrous aggregates as characterized by electron microscopy. Infrared spectroscopy suggests the ß-sheet conformation of the peptidic region in the gels. Using the Ma-IV ethanol/water bigel as the representative gel, entrapment and steady release of the anticancer drug docetaxel are demonstrated. Such bigels from rather simple amphipathic peptides that are easily synthesized and purified through solvent extraction could be attractive gelator candidates with potential application in drug delivery.

Aromatic-rich C-terminal region of LCI is a potent antimicrobial peptide in itself.

LCI is a 47-residue antimicrobial peptide produced by Bacillus subtilis. The peptide displays potent activity against plant pathogens, Xanthomonas and Pseudomonas. The peptide takes a compact 3-dimensional structure characterized by a four-stranded ß-sheet. The peptide is unusually rich in aromatic residues; 10 of the 47 residues are aromatic and 8 of them lie in the C-terminal region, LCI22-47. Here we report the antimicrobial activity of this C-terminal region against Gram-positive and Gram-negative bacteria. The C-terminal-amidated peptide displays potent activity against E. coli, methicillin and gentamicin-resistant S. aureus, and Xanthomonas oryzae pv. oryzae with lethal concentrations ≤4 µM. Membrane-binding assays indicate preferential binding to the negatively-charged lipids. The peptide permeabilizes the outer-membrane of E. coli indicating membrane-permeabilization as one of the mechanisms of killing. Interestingly, however, no inner-membrane permeabilization was observed, indicating that the membrane-permeabilization may not be the sole mechanism of action.

Limpid hydrogels from ß-turn motif-connected tandem repeats of Aß16-22.

Self-assembling peptides constitute an important class of functional biomaterials. A number of short amyloidogenic stretches have been identified from amyloid proteins. Such peptides, as such or through subtle modifications, can turn out to be promising candidates for functional biomaterials. End-capped Aß16-22, the well-studied amyloidogenic stretch from ß-amyloid, is reported to be non-hydrogelating up to 20 mM concentration. Here we investigated the hydrogelation propensity of Aß16-22 repeats connected through ß-turn-supporting motifs. The peptide repeats connected through Asn-Gly, Aib-DPro, and DPro-Gly formed transparent hydrogels at concentrations ≥2 mM. The repeats of the aromatic analog Aß16-22(F20Y) also resulted in similar hydrogels. Like other peptide-based gels reported earlier, these gels could trap the anticancer drug doxorubicin and displayed steady release in water. In addition, the gels supported the growth of mammalian cell lines, HEK-293 and RIN-5F. These data show that turn-inducing motifs can have marked effects on the hydrogelating propensity of self-assembling peptides.

Glycoprotein D peptide-based diagnostic approach for the detection of avian infectious laryngotracheitis antibodies.

Infectious laryngotracheitis (ILT) is a highly contagious respiratory disease of chickens, pheasants, and peafowl. It is caused by the alpha herpesvirus, infectious laryngotracheitis virus (ILTV). Glycoprotein D (gD) of ILTV is immunogenic and helps in its binding to the susceptible host cell receptor. In the present study, a recombinant gD protein was expressed in a prokaryotic system to develop a single serum dilution ELISA. In addition, two immunogenic peptides, corresponding to regions 77-89 and 317-328, were identified in gD protein. The peptides were synthesized using solid-phase peptide synthesis, purified using reversed-phase HPLC, and characterized using mass spectrometry. The peptides displayed a good titre and were found to be promising antigens to coat the ELISA plate to detect the ILTV antibodies in the serum sample. The developed ELISA showed 96.9% sensitivity, 87.5% specificity, and 95.3% accuracy as compared to OIE referenced standard indirect ILTV ELISA (whole viral coated). The assay may not differentiate vaccinated from infected birds when the flocks are administered with live attenuated vaccines. However, the assay could be useful to detect the disease condition in birds vaccinated with recombinant vaccine expressing glycoproteins other than gD. The developed ILTV single serum dilution ELISA could be an alternative to the existing diagnostics for the detection of ILTV antibodies.

Electric Field Disruption of Amyloid Aggregation: Potential Noninvasive Therapy for Alzheimer's Disease.

The aggregation of ß-amyloid peptides is a key event in the formative stages of Alzheimer's disease. Promoting folding and inhibiting aggregation was reported as an effective strategy in reducing Aß-elicited toxicity. This study experimentally investigates the influence of the external electric field (EF) and magnetic field (MF) of varying strengths on the in vitro fibrillogenesis of hydrophobic core sequence, Aß16-22, and its parent peptide, Aß1-42. Biophysical methods such as ThT fluorescence, static light scattering, circular dichroism, and infrared spectroscopy suggest that EF has a stabilizing effect on the secondary structure, initiating a conformational switch of Aß16-22 and Aß1-42 from ß to non-ß conformation. This observation was further corroborated by dynamic light scattering and transmission electron microscopic studies. To mimic in vivo conditions, we repeated ThT fluorescence assay with Aß1-42 in human cerebrospinal fluid to verify EF-mediated modulation. The self-seeding of Aß1-42 and cross-seeding with Aß1-40 to verify that the autocatalytic amplification of self-assembly as a result of secondary nucleation also yields comparable results in EF-exposed and unexposed samples. Aß-elicited toxicity of EF-treated samples in two neuroblastoma cell lines (SH-SY5Y and IMR-32) and human embryonic kidney cell line (HEK293) were found to be 15-38% less toxic than the EF untreated ones under identical conditions. Experiments with fluorescent labeled Aß1-42 to correlate reduced cytotoxicity and cell internalization suggest a comparatively smaller uptake of the EF-treated peptides. Our results provide a scientific roadmap for future noninvasive, therapeutic solutions for the treatment of Alzheimer's disease.

Antimicrobial peptides from C-terminal amphipathic region of E. coli FtsA.

Antimicrobial peptides constitute an indispensable component of innate immune system in organisms ranging from bacteria to man. Despite this, peptides lag far behind the conventional antibiotics in treating infections. The menace of multidrug-resistant bacteria, however, has revived the antimicrobial peptide research. We reasoned that the membrane-binding regions of bacterial proteins could be purposed to combat them. Here, we identify potent antimicrobial peptides from the C-terminal amphipathic helix of E. coli FtsA protein. The 11 and 13-residue peptides exhibited activity against E. coli, gentamicin-resistant MRSA, and C. albicans. The activity is little affected by the presence of salt and divalent cations. The peptides preferentially bind to the negatively-charged membranes as indicated by tryptophan fluorescence studies. The peptides permeabilize the E. coli outer and inner membranes at very promising concentrations suggesting membrane-disruption as one of the mechanisms of killing.

Patchy field sampling biases understanding of climate change impacts across the Arctic.

Effective societal responses to rapid climate change in the Arctic rely on an accurate representation of region-specific ecosystem properties and processes. However, this is limited by the scarcity and patchy distribution of field measurements. Here, we use a comprehensive, geo-referenced database of primary field measurements in 1,840 published studies across the Arctic to identify statistically significant spatial biases in field sampling and study citation across this globally important region. We find that 31% of all study citations are derived from sites located within 50 km of just two research sites: Toolik Lake in the USA and Abisko in Sweden. Furthermore, relatively colder, more rapidly warming and sparsely vegetated sites are under-sampled and under-recognized in terms of citations, particularly among microbiology-related studies. The poorly sampled and cited areas, mainly in the Canadian high-Arctic archipelago and the Arctic coastline of Russia, constitute a large fraction of the Arctic ice-free land area. Our results suggest that the current pattern of sampling and citation may bias the scientific consensuses that underpin attempts to accurately predict and effectively mitigate climate change in the region. Further work is required to increase both the quality and quantity of sampling, and incorporate existing literature from poorly cited areas to generate a more representative picture of Arctic climate change and its environmental impacts.

Interaction of MreB-derived antimicrobial peptides with membranes.

Antimicrobial peptides are critical components of defense systems in living forms. The activity is conferred largely by the selective membrane-permeabilizing ability. In our earlier work, we derived potent antimicrobial peptides from the 9-residue long, N-terminal amphipathic helix of E. coli MreB protein. The peptides display broad-spectrum activity, killing not only Gram-positive and Gram-negative bacteria but opportunistic fungus, Candida albicans as well. These results proved that membrane-binding stretches of bacterial proteins could turn out to be self-harming when applied from outside. Here, we studied the membrane-binding and membrane-perturbing potential of these peptides. Steady-state tryptophan fluorescence studies with tryptophan extended peptides, WMreB1-9 and its N-terminal acetylated analog, Ac-WMreB1-9 show preferential binding to negatively-charged liposomes. Both the peptides cause permeabilization of E. coli inner and outer-membranes. Tryptophan-lacking peptides, though permeabilize the outer-membrane efficiently, little permeabilization of the inner-membrane is observed. These data attest membrane-destabilization as the mechanism of rapid bacterial killing. This study is expected to motivate the research in identifying microbes' self-sequences to combat them.

Physiological acclimation dampens initial effects of elevated temperature and atmospheric CO2 concentration in mature boreal Norway spruce.

Physiological processes of terrestrial plants regulate the land-atmosphere exchange of carbon, water, and energy, yet few studies have explored the acclimation responses of mature boreal conifer trees to climate change. Here we explored the acclimation responses of photosynthesis, respiration, and stomatal conductance to elevated temperature and/or CO2 concentration ([CO2 ]) in a 3-year field experiment with mature boreal Norway spruce. We found that elevated [CO2 ] decreased photosynthetic carboxylation capacity (-23% at 25 °C) and increased shoot respiration (+64% at 15 °C), while warming had no significant effects. Shoot respiration, but not photosynthetic capacity, exhibited seasonal acclimation. Stomatal conductance at light saturation and a vapour pressure deficit of 1 kPa was unaffected by elevated [CO2 ] but significantly decreased (-27%) by warming, and the ratio of intercellular to ambient [CO2 ] was enhanced (+17%) by elevated [CO2 ] and decreased (-12%) by warming. Many of these responses differ from those typically observed in temperate tree species. Our results show that long-term physiological acclimation dampens the initial stimulation of plant net carbon assimilation to elevated [CO2 ], and of plant water use to warming. Models that do not account for these responses may thus overestimate the impacts of climate change on future boreal vegetation-atmosphere interactions.