Perspectives on Astringency Sensation: An Alternative Hypothesis on the Molecular Origin of Astringency

Flavor is one of the main drivers of food consumption and acceptability. It is associated with pleasure feels during eating. Flavor is a multimodal perception corresponding to the functional integration of information from the chemical senses: olfaction, gustation, and nasal and oral somatosensory inputs. As a result, astringency, as a sensation mediated by the trigeminal nerves, influences food flavor. Despite the importance of astringency in food consumer acceptance, the exact chemosensory mechanism of its detection and the nature of the receptors activated remain unknown. Herein, after reviewing the current hypotheses on the molecular origin of astringency, we proposed a ground-breaking hypothesis on the molecular mechanisms underpinning this sensation as a perspective for future research.

The Relationship Between Salivary Redox, Diet, and Food Flavor Perception

The mouth is the gateway for entrance of food and microorganisms into the organism. The oral cavity is bathed by saliva, which is thus the first fluid that food and microorganisms will face after their entrance. As a result, saliva plays different functions, including lubrication, predigestion, protection, detoxification, and even transport of taste compounds to chemoreceptors located in the taste buds. To ensure its function of protection, saliva contains reactive harmful compounds such as reactive oxygen species that are controlled and neutralized by the antioxidant activity of saliva. Several antioxidant molecules control the production of molecules such as reactive oxygen compounds, neutralize them and/or repair the damage they have caused. Therefore, a balance between reactive oxidant species and antioxidant compounds exists. At the same time, food can also contain antioxidant compounds, which can participate in the equilibrium of this balance. Numerous studies have investigated the effects of different food components on the antioxidant capacity of saliva that correspond to the ability of saliva to neutralize reactive oxygen species. Contradictory results have sometimes been obtained. Moreover, some antioxidant compounds are also cofactors of enzymatic reactions that affect flavor compounds. Recent studies have considered the salivary antioxidant capacity to explain the release of flavor compounds ex vivo or in vivo. This article aims to review the effect of food on the antioxidant capacity of saliva and the impact of salivary antioxidant capacity on flavor perception after a brief presentation of the different molecules involved.

[Placebo effects in pain therapy]

In the past few decades, research on pain and placebo analgesia has gained importance both scientifically and clinically. In this article, the current findings and focus of research as well as the significance of placebo research for assessing the effectiveness of pain medication are illustrated. The underlying mechanisms of placebo analgesia not only have implications for theoretical models but also offer clinically relevant guidelines for everyday interventions in pain treatment. However, many placebo phenomena are not fully understood and have to be investigated further in order to exploit the full potential of placebo effects. Interindividual differences and their inclusion in treatment will play a major role in this aspect.

Is there a role for tau glutathione transferases in tetrapyrrole metabolism and retrograde signalling in plants?

In plants, tetrapyrrole biosynthesis occurs in chloroplasts, the reactions being catalysed by stromal and membrane-bound enzymes. The tetrapyrrole moiety is a backbone for chlorophylls and cofactors such as sirohaems, haems and phytochromobilins. Owing to this diversity, the potential cytotoxicity of some precursors and the associated synthesis costs, a tight control exists to adjust the demand and the fluxes for each molecule. After synthesis, haems and phytochromobilins are incorporated into proteins found in other subcellular compartments. However, there is only very limited information about the chaperones and membrane transporters involved in the trafficking of these molecules. After summarizing evidence indicating that glutathione transferases (GST) may be part of the transport and/or degradation processes of porphyrin derivatives, we provide experimental data indicating that tau glutathione transferases (GSTU) bind protoporphyrin IX and haem moieties and use structural modelling to identify possible residues responsible for their binding in the active site hydrophobic pocket. Finally, we discuss the possible roles associated with the binding, catalytic transformation (i.e. glutathione conjugation) and/or transport of tetrapyrroles by GSTUs, considering their subcellular localization and capacity to interact with ABC transporters. This article is part of the theme issue 'Retrograde signalling from endosymbiotic organelles'.

"Bridging, brokering, and buffering": a theoretical exploration of school leaders' engagement with local school wellness policy implementation

Background

The Healthy, Hunger-Free Kids Act of 2010 (P.L. 111-296) prompted the expansion of federal requirements for local school wellness policies, which aim to improve health promoting practices across school districts in the USA. This qualitative study examined how school district superintendents—as key school leaders who are often listed as the district accountability figure for wellness policies applicable to kindergarten through 12th grade—engaged with wellness policy implementation. The inquiry was guided by evidence-informed implementation and leadership frameworks, including the Consolidated Framework for Implementation Research (CFIR) and “bridging, buffering, and brokering” strategies from education leadership theory.

Methods

We conducted focus groups and interviews with superintendents (n = 39) from 23 states. Interviews were recorded and professionally transcribed; transcripts were team-coded in Atlas.ti v8 using an iteratively revised coding guide that was informed by CFIR, pilot testing, and during weekly analyst meetings. Principles of constant comparative analysis were employed to develop themes.

Results

Most superintendents’ reported positive perspectives and personal motivations to engage with wellness policy implementation. Within the CFIR process domain, superintendents demonstrated adaptive leadership traits and employed a combination of “bridging, buffering, and brokering” strategies to lead implementation activities. Rather than focus on personal traits, an emphasis on specific strategies highlights actions that may be applied.

Conclusions

The findings offer practical strategies to support superintendents with implementation, as well as a formative contribution to the dearth of theoretical frameworks in school wellness literature, particularly by advancing the specific understanding of leadership roles within a broader implementation framework. The application of education theory allowed for a deeper inquiry into the potential ways that leaders’ strategies and engagement influences implementation more broadly.

Nintedanib in patients with progressive fibrosing interstitial lung diseases-subgroup analyses by interstitial lung disease diagnosis in the INBUILD trial: a randomised, double-blind, placebo-controlled, parallel-group trial

BACKGROUND

The INBUILD trial investigated the efficacy and safety of nintedanib versus placebo in patients with progressive fibrosing interstitial lung diseases (ILDs) other than idiopathic pulmonary fibrosis (IPF). We aimed to establish the effects of nintedanib in subgroups based on ILD diagnosis.

METHODS

The INBUILD trial was a randomised, double-blind, placebo-controlled, parallel group trial done at 153 sites in 15 countries. Participants had an investigator-diagnosed fibrosing ILD other than IPF, with chest imaging features of fibrosis of more than 10% extent on high resolution CT (HRCT), forced vital capacity (FVC) of 45% or more predicted, and diffusing capacity of the lung for carbon monoxide (DLco) of at least 30% and less than 80% predicted. Participants fulfilled protocol-defined criteria for ILD progression in the 24 months before screening, despite management considered appropriate in clinical practice for the individual ILD. Participants were randomly assigned 1:1 by means of a pseudo-random number generator to receive nintedanib 150 mg twice daily or placebo for at least 52 weeks. Participants, investigators, and other personnel involved in the trial and analysis were masked to treatment assignment until after database lock. In this subgroup analysis, we assessed the rate of decline in FVC (mL/year) over 52 weeks in patients who received at least one dose of nintedanib or placebo in five prespecified subgroups based on the ILD diagnoses documented by the investigators: hypersensitivity pneumonitis, autoimmune ILDs, idiopathic non-specific interstitial pneumonia, unclassifiable idiopathic interstitial pneumonia, and other ILDs. The trial has been completed and is registered with ClinicalTrials.gov, number NCT02999178.

FINDINGS

Participants were recruited between Feb 23, 2017, and April 27, 2018. Of 663 participants who received at least one dose of nintedanib or placebo, 173 (26%) had chronic hypersensitivity pneumonitis, 170 (26%) an autoimmune ILD, 125 (19%) idiopathic non-specific interstitial pneumonia, 114 (17%) unclassifiable idiopathic interstitial pneumonia, and 81 (12%) other ILDs. The effect of nintedanib versus placebo on reducing the rate of FVC decline (mL/year) was consistent across the five subgroups by ILD diagnosis in the overall population (hypersensitivity pneumonitis 73·1 [95% CI -8·6 to 154·8]; autoimmune ILDs 104·0 [21·1 to 186·9]; idiopathic non-specific interstitial pneumonia 141·6 [46·0 to 237·2]; unclassifiable idiopathic interstitial pneumonia 68·3 [-31·4 to 168·1]; and other ILDs 197·1 [77·6 to 316·7]; p=0·41 for treatment by subgroup by time interaction). Adverse events reported in the subgroups were consistent with those reported in the overall population.

INTERPRETATION

The INBUILD trial was not designed or powered to provide evidence for a benefit of nintedanib in specific diagnostic subgroups. However, its results suggest that nintedanib reduces the rate of ILD progression, as measured by FVC decline, in patients who have a chronic fibrosing ILD and progressive phenotype, irrespective of the underlying ILD diagnosis.

FUNDING

Boehringer Ingelheim.

Open ventral hernia repair with a composite ventral patch - final results of a multicenter prospective study

Background

This study assessed clinical outcomes, including safety and recurrence, from the two-year follow-up of patients who underwent open ventral primary hernia repair with the use of the Parietex™ Composite Ventral Patch (PCO-VP).

Methods

A prospective single-arm, multicenter study of 126 patients undergoing open ventral hernia repair for umbilical and epigastric hernias with the PCO-VP was performed.

Results

One hundred twenty-six subjects (110 with umbilical hernia and 16 with epigastric hernia) with a mean hernia diameter of 1.8 cm (0.4–4.0) were treated with PCO-VP. One hundred subjects completed the two-year study. Cumulative hernia recurrence was 3.0% (3/101; 95%CI: 0.0–6.3%) within 24 months. Median Numeric Rating Scale pain scores improved from 2 [0–10] at baseline to 0 [0–3] at 1 month (P < 0.001) and remained low at 24 months 0 [0–6] (P < 0.001). 99% (102/103) of the patients were satisfied with their repair at 24 months postoperative.

Conclusions

The use of PCO-VP to repair primary umbilical and epigastric defects yielded a low recurrence rate, low postoperative and chronic pain, and high satisfaction ratings, confirming that PCO-VP is effective for small ventral hernia repair in the two-year term after implantation.

Trial registration

The study was registered publically at clinicaltrials.gov (NCT01848184 registered May 7, 2013).

Corticosteroid signaling at the brain-immune interface impedes coping with severe psychological stress

The immune system supports brain plasticity and homeostasis, yet it is prone to changes following psychological stress. Thus, it remains unclear whether and how stress-induced immune alterations contribute to the development of mental pathologies. Here, we show that following severe stress in mice, leukocyte trafficking through the choroid plexus (CP), a compartment that mediates physiological immune-brain communication, is impaired. Blocking glucocorticoid receptor signaling, either systemically or locally through its genetic knockdown at the CP, facilitated the recruitment of Gata3- and Foxp3-expressing T cells to the brain and attenuated post-traumatic behavioral deficits. These findings functionally link post-traumatic stress behavior with elevated stress-related corticosteroid signaling at the brain-immune interface and suggest a novel therapeutic target to attenuate the consequences of severe psychological stress.

The structure of Trametes versicolor glutathione transferase Omega 3S bound to its conjugation product glutathionyl-phenethylthiocarbamate reveals plasticity of its active site

Trametes versicolor glutathione transferase Omega 3S (TvGSTO3S) catalyzes the conjugation of isothiocyanates (ITC) with glutathione (GSH). Previously, this isoform was investigated in depth both biochemically and structurally. Structural analysis of complexes revealed the presence of a GSH binding site (G site) and a deep hydrophobic binding site (H site) able to bind plant polyphenols. In the present study, crystals of apo TvGSTO3S were soaked with glutathionyl-phenethylthiocarbamate, the product of the reaction between GSH and phenethyl isothiocyanate (PEITC). On the basis of this crystal structure, we show that the phenethyl moiety binds in a new site at loop β₂ -α₂ while the glutathionyl part exhibits a particular conformation that occupies both the G site and the entrance to the H site. This binding mode is allowed by a conformational change of the loop β₂ -α₂ at the enzyme active site. It forms a hydrophobic slit that stabilizes the phenethyl group at a distinct site from the previously described H site. Structural comparison of TvGSTO3S with drosophila DmGSTD2 suggests that this flexible loop could be the region that binds PEITC for both isoforms. These structural features are discussed in a catalytic context.

Functional, Structural and Biochemical Features of Plant Serinyl-Glutathione Transferases

Glutathione transferases (GSTs) belong to a ubiquitous multigenic family of enzymes involved in diverse biological processes including xenobiotic detoxification and secondary metabolism. A canonical GST is formed by two domains, the N-terminal one adopting a thioredoxin (TRX) fold and the C-terminal one an all-helical structure. The most recent genomic and phylogenetic analysis based on this domain organization allowed the classification of the GST family into 14 classes in terrestrial plants. These GSTs are further distinguished based on the presence of the ancestral cysteine (Cys-GSTs) present in TRX family proteins or on its substitution by a serine (Ser-GSTs). Cys-GSTs catalyze the reduction of dehydroascorbate and deglutathionylation reactions whereas Ser-GSTs catalyze glutathione conjugation reactions and eventually have peroxidase activity, both activities being important for stress tolerance or herbicide detoxification. Through non-catalytic, so-called ligandin properties, numerous plant GSTs also participate in the binding and transport of small heterocyclic ligands such as flavonoids including anthocyanins, and polyphenols. So far, this function has likely been underestimated compared to the other documented roles of GSTs. In this review, we compiled data concerning the known enzymatic and structural properties as well as the biochemical and physiological functions associated to plant GSTs having a conserved serine in their active site.

Chem/bio sensing with non-classical light and integrated photonics

Modern quantum technology currently experiences extensive advances in applicability in communications, cryptography, computing, metrology and lithography. Harnessing this technology platform for chem/bio sensing scenarios is an appealing opportunity enabling ultra-sensitive detection schemes. This is further facilliated by the progress in fabrication, miniaturization and integration of visible and infrared quantum photonics. Especially, the combination of efficient single-photon sources together with waveguiding/sensing structures, serving as active optical transducer, as well as advanced detector materials is promising integrated quantum photonic chem/bio sensors. Besides the intrinsic molecular selectivity and non-destructive character of visible and infrared light based sensing schemes, chem/bio sensors taking advantage of non-classical light sources promise sensitivities beyond the standard quantum limit. In the present review, recent achievements towards on-chip chem/bio quantum photonic sensing platforms based on N00N states are discussed along with appropriate recognition chemistries, facilitating the detection of relevant (bio)analytes at ultra-trace concentration levels. After evaluating recent developments in this field, a perspective for a potentially promising sensor testbed is discussed for reaching integrated quantum sensing with two fiber-coupled GaAs chips together with semiconductor quantum dots serving as single-photon sources.

Optic Nerve Degeneration and Potential Neuroprotection: Implications for Glaucoma

In order to study the course of optic nerve degeneration and devise possible ways to achieve neuroprotection, a well-controlled, animal model of partial crush injury of the optic nerve was used. Following the controlled partial crush injury of the rat optic nerve, quantitative morphological and electrophysiological measurements were made of primary and secondary neuronal losses. The neuroprotective effects of NMDA-receptor antagonists and α2-adrenoreceptor agonists were also studied. The results suggested that the ongoing progression of the optic nerve degeneration in glaucoma might be a consequence of the toxic extracellular environment produced by neurons that degenerate as a result of the primary cause of the disease (such as increased IOP).

Fibrinolysis, Fibrinogen and Factor XIII in New Born Infants

Fibrinolysis and the last stage of clotting were examined in 20 healthy infants on days 1-4 after birth. Plasminogen was constantly at half its normal level: 1.2-1.4 u/ml. The euglobulin lysis was increased only on day 1 in 50% of the cases. The mean values on days 1 and 4 showed a statistically significant difference: 0.45 ± 0.20 and 0.14 ± 0.05 (t = 2.1 p < 0.05). Fibrinogen was low or low normal at birth (mean values: 230 ± 57 mg%) but increased significantly in the next days reaching a mean of 293 ± 41 mg% on day 4 (t = 3.6 ρ < 0.001). Factor XIII was normal in all cases. Increased fibrinolysis in day 1 is probably due to a high level of activator at birth and the low plasminogen and fibrinogen are probably a consequence of the physiological „immaturity” of the liver.

Molecular recognition of wood polyphenols by phase II detoxification enzymes of the white rot Trametes versicolor

Wood decay fungi have complex detoxification systems that enable them to cope with secondary metabolites produced by plants. Although the number of genes encoding for glutathione transferases is especially expanded in lignolytic fungi, little is known about their target molecules. In this study, by combining biochemical, enzymatic and structural approaches, interactions between polyphenols and six glutathione transferases from the white-rot fungus Trametes versicolor have been demonstrated. Two isoforms, named TvGSTO3S and TvGSTO6S have been deeply studied at the structural level. Each isoform shows two distinct ligand-binding sites, a narrow L-site at the dimer interface and a peculiar deep hydrophobic H-site. In TvGSTO3S, the latter appears optimized for aromatic ligand binding such as hydroxybenzophenones. Affinity crystallography revealed that this H-site retains the flavonoid dihydrowogonin from a partially purified wild-cherry extract. Besides, TvGSTO6S binds two molecules of the flavonoid naringenin in the L-site. These data suggest that TvGSTO isoforms could interact with plant polyphenols released during wood degradation.