Crystallography reveals metal-triggered restructuring of ß-hairpins.

Metal binding to ß-sheets occurs in many metalloproteins and is also implicated in the pathology of Alzheimer's disease. De novo designed metallo-ß-sheets have been pursued as models and mimics of these proteins. However, no crystal structures of canonical ß-sheet metallopeptides have yet been obtained, in stark contrast to many examples for ɑ-helical metallopeptides, leading to a poor understanding for their chemistry. To address this, we have engineered tryptophan zippers, stable 12-residue ß-sheet peptides, to bind Cu(II) ions and obtained crystal structures through single crystal X-ray diffraction (SC-XRD). We find that metal binding triggers several unexpected supramolecular assemblies that demonstrate the range of higher-order structures available to metallo-ß-sheets. Overall, these findings underscore the importance of crystallography in elucidating the rich structural landscape of metallo-ß-sheet peptides.

Diverse Proteomimetic Frameworks via Rational Design of π-Stacking Peptide Tectons.

Peptide-based frameworks aim to integrate protein architecture into solid-state materials using simpler building blocks. Despite the growing number of peptide frameworks, there are few strategies to rationally engineer essential properties like pore size and shape. Designing peptide assemblies is generally hindered by the difficulty of predicting complex networks of weak intermolecular interactions. Peptides conjugated to polyaromatic groups are a unique case where assembly appears to be strongly driven by π-π interactions, suggesting that rationally adjusting the geometry of the π-stackers could create novel structures. Here, we report peptide elongation as a simple mechanism to predictably tune the angle between the π-stacking groups to produce a remarkable diversity of pore shapes and sizes, including some that are mesoporous. Notably, rapid jumps in pore size and shape can occur with just a single amino acid insertion. The geometry of the π-stacking residues also significantly influences framework structure, representing an additional dimension for tuning. Lastly, sequence identity can also indirectly modulate the π-π interactions. By correlating each of these factors with detailed crystallographic data, we find that, despite the complexity of peptide structure, the shape and polarity of the tectons are straightforward predictors of framework structure. These guidelines are expected to accelerate the development of advanced porous materials with protein-like capabilities.

Transition of survival strategies under global climate shifts in the grape family.

Faced with environmental changes, plants may either move to track their ancestral niches or evolve to adapt to new niches. Vitaceae, the grape family, has evolved diverse adaptive traits facilitating a global expansion in wide-ranging habitats, making it ideal for investigating transition between move and evolve strategies and exploring the underlying mechanisms. Here we inferred the patterns of biogeographic diversification and trait evolution in Vitaceae based on a robust phylogeny with dense sampling including 495 species (~52% of Vitaceae species). Vitaceae probably originated from Asia-the diversity centre of extant genera and the major source of dispersals. Boundaries of the Eocene, Oligocene and Miocene were identified as turning points in shifting strategies. A significant decrease in move strategy was identified during the Oligocene, followed by increases in move and evolve. After the Miocene, evolve began to dominate, during which increased niche opportunities and key trait innovations played important roles.

Glycoside constituents from Cayratia geniculata.

Using various chromatographic separations, six glycoside derivatives (1-6), including one new ent-labdane glucoside named cayratioside (1), were isolated from the methanol extract of Cayratia geniculata stems and leaves. Their structures were elucidated by detailed analysis of the 1D, 2D NMR, and HRESIQTOF mass spectra. The inhibitory effect of 1-6 on LPS-induced NO production in RAW264.7 cells was also evaluated. Among isolated compounds, 1 exhibited moderate activity with an IC50 value of 59.65 ± 1.85 µM.

Caffeoylquinic acid esters, lignans and flavones from Yua thomsonii with cytotoxic and nitric oxide inhibitory activities.

Phytochemical study on the aerial parts of Yua thomsonii resulted in the isolation of 11 secondary metabolites, including a new caffeoyl quinic acid derivative, 3-O-trans-caffeoyl-4-O-acetylquinic acid methyl ester (1), a new dihydrobenzofuran neolignan, 3,5-dimethoxy-4-(1″,3″-dihydroxy-2″-propyloxyl)-4',7-epoxy-8,5'-neolignan-4,9,9'-triol (3) and nine known compounds, methyl 4-O-coumaroylquinate (2), (7S*,8S*)-3-methoxy-3',7-epoxy-8,4'-oxyneolignan-4,9,9'-triol (4), kompasinol A (5), lyoniresinol (6), schizandriside (7), (-)-isolariciresinol 3a-O-ß-D-xylopyranoside (8), lyoniside (9), vitexin (10) and luteolin 4'-O-ß-glucopyranoside (11). Their structures were elucidated using comprehensive spectroscopic methods, including 1D and 2D NMR and HRESI mass spectra. The absolute configurations of 1 and 3 were deduced by electronic circular dichroism spectroscopy. Compounds 1, 3, 5 and 6 exhibited nitric oxide (NO) inhibitory effects, with IC50 values ranging from 12.18 to 29.45 µM. However, compounds 1, 3, 6 and 8 were non-cytotoxic towards HepG2 and MCF-7 carcinoma cells.

Pore Restructuring of Peptide Frameworks by Mutations at Distal Packing Residues.

Porous framework materials are highly useful for catalysis, adsorption, and separations. Though they are usually made from inorganic and organic building blocks, recently, folded peptides have been utilized for constructing frameworks, opening up an enormous structure-space for exploration. These peptides assemble in a metal-free fashion using π-stacking, H-bonding, dispersion forces, and the hydrophobic effect. Manipulation of pore-defining H-bonding residues is known to generate new topologies, but the impact of mutations in the hydrophobic packing region facing away from the pores is less obvious. To explore their effects, we synthesized variants of peptide frameworks with mutations in the hydrophobic packing positions and found by single-crystal X-ray crystallography (SC-XRD) that they induce significant changes to the framework pore structure. These structural changes are driven by a need to maximize van der Waals interactions of the nonpolar groups, which are achieved by various mechanisms including helix twisting, chain flipping, chain offsetting, and desymmetrization. Even subtle changes to the van der Waals interface, such as the introduction of a methyl group or isomeric replacement, result in significant pore restructuring. This study shows that the dispersion interactions upholding a peptide material are a rich area for structural engineering.

Noncovalent Peptide Assembly Enables Crystalline, Permutable, and Reactive Thiol Frameworks.

Though thiols are exceptionally versatile, their high reactivity has also hindered the synthesis and characterization of well-defined thiol-containing porous materials. Leveraging the mild conditions of the noncovalent peptide assembly, we readily synthesized and characterized a number of frameworks with thiols displayed at many unique positions and in several permutations. Importantly, nearly all assemblies were structurally determined using single-crystal X-ray diffraction to reveal their rich sequence-structure landscape and the cooperative noncovalent interactions underlying their assembly. These observations and supporting molecular dynamics calculations enabled rational engineering by the positive and negative design of noncovalent interactions. Furthermore, the thiol-containing frameworks undergo diverse single-crystal-to-single-crystal reactions, including toxic metal ion coordination (e.g., Cd2+, Pb2+, and Hg2+), selective uptake of Hg2+ ions, and redox transformations. Notably, we find a framework that supports thiol-nitrosothiol interconversion, which is applicable for biocompatible nitric oxide delivery. The modularity, ease of synthesis, functionality, and well-defined nature of these peptide-based thiol frameworks are expected to accelerate the design of complex materials with reactive active sites.

Clinical Epidemiology Features and Risk Factors for Acute Diarrhea Caused by Rotavirus A in Vietnamese Children.

Introduction: Acute diarrhea caused by group A rotavirus (RVA) is a leading cause of morbidity and mortality globally in children less than 5 years old. Acute diarrhea caused by RVA is often manifested by loose/watery stool leading to different degrees of dehydration. The detection of risk factors, diagnosis, and prompt treatment of acute diarrhea caused by RVA is critical. We aimed to describe clinical epidemiological features of acute diarrhea caused by RVA and its associated risk factors. Subjects and Method. We conducted a cross-sectional study that included 321 children under 5 years old with acute diarrhea at Haiphong Children's Hospital, Vietnam, from 1 August 2019 to 31 July 2020. Results: Among the 321 children included in our analysis, 221 (68.8%) children were positive for RVA. Males represented 61.1% of cases, 41.2% of children were in the 12-<24-month age group, and the majority of cases were among children in suburban areas (71.5%). Clinical manifestations included loose and watery stool (100%), vomiting-fever-loose/watery stool (57.9%), vomiting-loose/watery stool (83.2%), fever-loose/watery stool (58.8%), dehydration (30%), hyponatremia (22.1%), hypernatremia (1.4%), and hypokalemia (15%). Risk factors for acute diarrhea caused by RVA included history of diarrhea, not exclusive breastfeeding in the first 6 months, living area, maternal education, and income. Conclusions: Acute diarrhea due to RVA was very prevalent in children under 5 years old. Clinical manifestations included a high prevalence of loose/watery stools/day and dehydration with electrolyte disorder. Mothers should exclusively breastfeed their children for the first 6 months to avoid the risk of acute diarrhea caused by RVA.

Optogenetic spinal stimulation promotes new axonal growth and skilled forelimb recovery in rats with sub-chronic cervical spinal cord injury.

Objective.Spinal cord injury (SCI) leads to debilitating sensorimotor deficits that greatly limit quality of life. This work aims to develop a mechanistic understanding of how to best promote functional recovery following SCI. Electrical spinal stimulation is one promising approach that is effective in both animal models and humans with SCI. Optogenetic stimulation is an alternative method of stimulating the spinal cord that allows for cell-type-specific stimulation. The present work investigates the effects of preferentially stimulating neurons within the spinal cord and not glial cells, termed 'neuron-specific' optogenetic spinal stimulation. We examined forelimb recovery, axonal growth, and vasculature after optogenetic or sham stimulation in rats with cervical SCI.Approach.Adult female rats received a moderate cervical hemicontusion followed by the injection of a neuron-specific optogenetic viral vector ipsilateral and caudal to the lesion site. Animals then began rehabilitation on the skilled forelimb reaching task. At four weeks post-injury, rats received a micro-light emitting diode (µLED) implant to optogenetically stimulate the caudal spinal cord. Stimulation began at six weeks post-injury and occurred in conjunction with activities to promote use of the forelimbs. Following six weeks of stimulation, rats were perfused, and tissue stained for GAP-43, laminin, Nissl bodies and myelin. Location of viral transduction and transduced cell types were also assessed.Main Results.Our results demonstrate that neuron-specific optogenetic spinal stimulation significantly enhances recovery of skilled forelimb reaching. We also found significantly more GAP-43 and laminin labeling in the optogenetically stimulated groups indicating stimulation promotes axonal growth and angiogenesis.Significance.These findings indicate that optogenetic stimulation is a robust neuromodulator that could enable future therapies and investigations into the role of specific cell types, pathways, and neuronal populations in supporting recovery after SCI.

Anti-Alzheimer's Activity of Polyphenolic Stilbene-Rich Acetone Fraction of the Oil-Removed Seeds of Passiflora edulis: in Vivo and in Silico Studies.

The stilbene-rich acetone fraction in high yield (6.6 %, PEAS) of Passiflora edulis Sims was prepared and evaluated for neuroprotective activity in murine Alzheimer's disease model induced by aluminum chloride and D-galactose. The phytochemical and HPLC-DAD-MS analysis of the polyphenolic stilbene-rich acetone fraction showed that it contained different stilbenes including trans-piceatannol, scirpusins A-B and cassigarol E. The total phenolic content (TPC) of PEAS was 413.87±1.71 mg GAE eqv/g. The neuroprotective activity of PEAS is typically presented in the Morris water maze-reference Spatial Memory test, where the Alzheimer's mice treated at 100 mg/kg (Alz-ED1) and 200 mg/kg (Alz-ED2) spent less than 47 % and 66 % of the time, respectively, than the Alzheimer's model mice (Alz). Two simple stilbenes, trans-piceatannol and trans-resveratrol, showed selectively inhibitory activity in silico against acetylcholinesterase (AChE). Two stilbene dimers, cassigarol E and scirpusin A, exhibited low nanomolar inhibitory potential against AChE and butyrylcholinesterase (BChE), significantly lower than those of the positive control, donepezil and tacrine. These findings suggest that the stilbenes from P. edulis seeds, particularly the stilbene dimers, warrant further investigation as potential neuroprotective candidates in the prevention of cognitive deficits associated with Alzheimer's disease.

Atractylodes macrocephala Rhizomes Contain Anti-inflammatory Sesquiterpenes.

Two new compounds, named eudesm-4(15),7-diene-3α,9ß,11-triol (1) and eudesm-4(15),7-diene-1ß,3α,9ß,11-tetraol (2) together with three known sesquiterpene lactones (1S,5R,7R,10R)-secoatractylolactone (3), (1S,5R,7R,10R)-secoatractylolactone-11-O-ß-D-glucopyranoside (4) atractylenolide III (5) were isolated from the rhizomes of Atractylodes macrocephala. Their structures were elucidated by using one-dimensional (1D) and 2D-NMR spectra and high resolution electrospray ionization (HR-ESI)-MS data. Compound 5 exhibited the most active anti-inflammatory activity with IC50 values of 27.5 µM in inhibiting of nitric oxide production. Compounds 1, 2, and 3 showed moderate effects while compound 4 was inactive.

Undescribed chalcone and stilbene constituents from Lysimachia baviensis and their anti-inflammatory effect.

The chemical composition and anti-inflammatory activity of the endemic Lysimachia baviensis were investigated for the first time in this study. A phytochemical fractionation of the methanol extract of L. baviensis resulted in the isolation of a new stilbene (bavienside A, 1) and two new chalcone glycosides (baviensides B and C, 2 and 3). Their structures were elucidated via the interpretation of NMR and HRESIMS spectroscopic data. Compounds 1-3 strongly inhibited the production of nitric oxide in LPS-induced RAW264.7 cells with the IC50 values of 6.23, 2.86 and 3.51 µM, respectively. The C-acetylstilbene and carbomethyl chalcone structures in compound 1 and 3 were found for the first time from natural source and could be important markers for chemotaxonomy of Lysimachia baviensis.

Secondary metabolites from the fruit peels of Durio zibethinus L. and their cytotoxic activity.

Three new glucosides, ziberthinosides A-C (1-3), and six known compounds, cleomiscosins A-D (4-7), sporogen AO-2 (8) and sapinofuranone A (9), were isolated from a methanol extract of Durio zibethinus fruit peels. Their chemical structures were elucidated by analyses of their 1 D/2D NMR and HR-ESI-MS data as well as by comparison with the literature values. The absolute configuration of sporogen AO-2 (8) was confirmed by ECD calculation. Of the isolates, compounds 8 and 9 were cytotoxic toward all MCF7, HepG2 and SK-LU-1 cell lines, with IC50 values ranging from 10.7 to 34.9 µM. Our results contribute to better understanding of the chemical constituents of the high valued durian fruit and their pharmacological effect, such as cytotoxicity.

Antimicrobial secondary metabolites from the aerial parts of Perilla frutescens.

Phytochemical research of Perilla frutescens aerial parts led to isolation of 12 secondary metabolites, including one new 3-benzoxepin glucoside, perillafrutoside A (1), one new megastigmane glycoside, perillafrutoside B (2), and 10 known compounds. Their chemical structures were identified based on 1D/2D NMR, HRESIMS, and ECD spectroscopic analyses. The structure of 2 was elucidated based on revision of the previously reported stereoisomer, (6R,9R)-blumenyl α-L-rhamnopyranosyl-(1→6)-ß-D-glucopyranoside. Evaluation of their antimicrobial effect revealed that compounds 1 and 5-11 inhibit Enterococcus faecalis growth, compounds 6, 7 and 9 suppress Staphylococcus aureus growth, whereas compounds 6 and 11 attenuate Candida albicans growth. This is the first report of the isolation of 3-5, 8-10 and 12 from the genus Perilla and the antimicrobial effect of compounds 3, 8 and 10.

Surveillance of pfhrp2 and pfhrp3 gene deletions among symptomatic Plasmodium falciparum malaria patients in Central Vietnam.

BACKGROUND: Malaria rapid diagnostic tests (RDTs) remain the main point-of-care tests for diagnosis of symptomatic Plasmodium falciparum malaria in endemic areas. However, parasites with gene deletions in the most common RDT target, histidine rich protein 2 (pfhrp2/HRP2), can produce false-negative RDT results leading to inadequate case management. The objective of this study was to determine the prevalence of hrp2/3 deletions causing false-negative RDT results in Vietnam (Gia Lai and Dak Lak provinces). METHODS: Individuals presenting with malaria symptoms at health facilities were screened for P. falciparum infection using light microscopy and HRP2-RDT (SD Bioline Malaria Antigen Pf/Pv RDT, Abbott). Microscopically confirmed P. falciparum infections were analysed for parasite species by 18S rRNA qPCR, and pfhrp2 and pfhrp3 exon2 deletions were investigated by nested PCR. pfhrp2 amplicons were sequenced by the Sanger method and HRP2 plasma levels were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: The prevalence of false-negative RDT results among symptomatic cases was 5.6% (15/270). No pfhrp2 and pfhrp3 deletions were identified. False-negative RDT results were associated with lower parasite density (p = 0.005) and lower HRP2 plasma concentrations (p < 0.001), as compared to positive RDT. CONCLUSIONS: The absence of hrp2/3 deletions detected in this survey suggests that HRP2-based malaria RDTs remain effective for the diagnosis of symptomatic P. falciparum malaria in Central Vietnam.

Essential Oils from Vietnamese Asteraceae for Environmentally Friendly Control of Aedes Mosquitoes.

Mosquitoes, in addition to being a biting nuisance, are vectors of several pathogenic viruses and parasites. As a continuation of our work identifying abundant and/or invasive plant species in Vietnam for use as ecologically friendly pesticidal agents, we obtained the essential oils of Blumea lacera, Blumea sinuata, Emilia sonchifolia, Parthenium hysterophorus, and Sphaeranthus africanus; analyzed the essential oils using gas chromatographic techniques; and screened the essential oils for mosquito larvicidal activity against Aedes aegypti and Aedes albopictus. The most active larvicidal essential oils were B. sinuata, which was rich in thymohydroquinone dimethyl ether (29.4%), (E)-ß-caryophyllene (19.7%), α-pinene (8.8%), germacrene D (7.8%), and α-humulene (4.3%), (24-h LC50 23.4 and 29.1 µg/mL) on Ae. aegypti and Ae. albopictus, respectively, and Emilia sonchifolia, dominated by 1-undecene (41.9%) and germacrene D (11.0%), (24-h LC50 30.1 and 29.6 µg/mL) on the two mosquito species. The essential oils of P. hysterophorus and S. africanus were also active against mosquito larvae. Notably, B. sinuata, P. hysterophorus, and S. africanus essential oils were not toxic to the non-target water bug, Diplonychus rusticus. However, E. sonchifolia essential oil showed insecticidal activity (24-h LC50 48.1 µg/mL) on D. rusticus. Based on these results, B. sinuata, P. hysterophorus, and S. africanus essential oils appear promising for further investigations.

The first years of liver transplantation: experiences at a single center.

Background: The aim of this study was to analyze the first stages of progress in liver transplantation (LT) at a single center in Vietnam. Methods: This study analyzed data from patients and donors who participated in the LT program between August 2018 and December 2021 at University Medical Center, Ho Chi Minh City. Study measures included any difficulties encountered, as well as the post-LT outcomes for living donor LT (LDLT) and deceased donor LT (DDLT). The chi-square test and Kaplan Meier survival analysis were used to test the factors that influenced the outcomes. Results: A total of 18 adult recipients with LT (LDLT, n=16; DDLT, n=2) were included (mean age, 55.2±2.6 years; male, 88.9%). The most common post-LT complications were middle hepatic venous stenosis (20%) and graft rejection (22.2%). These complications were observed in LDLT patients. For DDLT, graft rejection (50%) was the only complication recorded. The survival rates for recipients at 3 months, 6 months, and 1 year were 100%, 88.9%, and 88.9%, respectively. The LDs had their right livers without the middle hepatic veins harvested, and biliary leakage (6.25%) was the only complication observed. There were no deaths among recipients or LDs during the operations or hospital stays. Conclusions: This study provides key details about the process of LT, and these positive outcomes support LT as an important therapy for end-stage liver disease and early hepatocellular carcinomas.

Multi-locus genome-wide association studies reveal novel alleles for flowering time under vernalisation and extended photoperiod in a barley MAGIC population.

KEY MESSAGE: Key genes controlling flowering and interactions of different photoperiod alleles with various environments were identified in a barley MAGIC population. A new candidate gene for vernalisation requirements was also detected. Optimal flowering time has a major impact on grain yield in crop species, including the globally important temperate cereal crop barley (Hordeum vulgare L.). Understanding the genetics of flowering is a key avenue to enhancing yield potential. Although bi-parental populations were used intensively to map genes controlling flowering, their lack of genetic diversity requires additional work to obtain desired gene combinations in the selected lines, especially when the two parental cultivars did not carry the genes. Multi-parent mapping populations, which use a combination of four or eight parental cultivars, have higher genetic and phenotypic diversity and can provide novel genetic combinations that cannot be achieved using bi-parental populations. This study uses a Multi-parent advanced generation intercross (MAGIC) population from four commercial barley cultivars to identify genes controlling flowering time in different environmental conditions. Genome-wide association studies (GWAS) were performed using 5,112 high-quality markers from Diversity Arrays Technology sequencing (DArT-seq), and Kompetitive allele-specific polymerase chain reaction (KASP) genetic markers were developed. Phenotypic data were collected from fifteen different field trials for three consecutive years. Planting was conducted at various sowing times, and plants were grown with/without additional vernalisation and extended photoperiod treatments. This study detected fourteen stable regions associated with flowering time across multiple environments. GWAS combined with pangenome data highlighted the role of CEN gene in flowering and enabled the prediction of different CEN alleles from parental lines. As the founder lines of the multi-parental population are elite germplasm, the favourable alleles identified in this study are directly relevant to breeding, increasing the efficiency of subsequent breeding strategies and offering better grain yield and adaptation to growing conditions.

Assembly of π-Stacking Helical Peptides into a Porous and Multivariable Proteomimetic Framework.

The evolution of proteins from simpler, self-assembled peptides provides a powerful blueprint for the design of complex synthetic materials. Previously, peptide-metal frameworks using short sequences (≤3 residues) have shown great promise as proteomimetic materials that exhibit sophisticated capabilities. However, their development has been hindered due to few variable residues and restricted choice of side-chains that are compatible with metal ions. Herein, we developed a noncovalent strategy featuring π-stacking bipyridyl residues to assemble much longer peptides into crystalline frameworks that tolerate even previously incompatible acidic and basic functionalities and allow an unprecedented level of pore variations. Single-crystal X-ray structures are provided for all variants to guide and validate rational design. These materials exhibit hallmark proteomimetic behaviors such as guest-selective induced fit and assembly of multimetallic units. Significantly, we demonstrate facile optimization of the framework design to substantially increase affinity toward a complex organic molecule.