bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms of Orthosteric Agonist and Allosteric Modulator Activity at mGlu7
Authors: Lei Xia , Rodriguez Alice , Niswender Colleen 
Published: May 2022

Metabotropic glutamate receptor 7 (mGlu7) is a dimeric, group III metabotropic glutamate (mGlu) receptor. It is a G protein‐coupled receptor that acts to modulate neurotransmission across many brain structures. mGlu7 is most highly expressed presynaptically in neurons and is widely distributed in the central nervous system (CNS) and body. Mutations, deletions, or decreases in mGlu7 result in symptoms and phenotypes of neurodevelopmental disorders in humans and mice, including Rett syndrome.Our group is focused on developing new ligands that interact with mGlu7 to understand the therapeutic potential of the receptor in various CNS disorders. However, in vitromolecular pharmacology studies show that the orthosteric ligand, glutamate, has a low affinity for mGlu7 that limits its ability to be routinely used for drug screening. An alternative agonist, L‐AP4, is a synthetic compound that, while not produced naturally in vivo, activates mGlu7 with higher affinity than glutamate. However, our preliminary research indicates that there are differences in the profiles of positive allosteric modulators (PAMs) when assessed using glutamate versus L‐AP4. This difference creates a challenge for the development of mGlu7‐selective PAMs, and the focus of our current studies is to understand the difference between these two agonists in activating the mGlu7 receptor.The mGlu receptors function as constitutive dimers. Here, we hypothesize that glutamate and L‐AP4 activate mGlu7 either via a different number of agonist binding sites or via distinct effector interactions; additionally, we hypothesize that mGlu7potentiation by structurally distinct PAMs may differ based on these agonists. We have found that two agonist binding sites are required for mGlu7 activation for both glutamate and L‐AP4, and two G‐protein/effector binding sites are required for any glutamate‐dependent activation. L‐AP4, however, can partially activate the dimer with one functioning G‐protein binding site, and two G‐protein binding sites fully activate mGlu7 with L‐AP4. The PAM VU0422288 requires two agonist binding sites to potentiate mGlu7; in contrast, VU0155094 and VU6005469 show partial potentiation of mGlu7 if one of the agonist binding sites is mutated. VU0422288 induces partial potentiation of mGlu7 with only one functional G‐protein binding site and requires two G‐protein binding sites to induce full potentiation. In contrast, other PAMs (VU0155094 and VU6005469) can fully potentiate mGlu7 activity with one functioning G‐protein binding site. Additionally, VU0422288 also shows elevated efficacy with L‐AP4 compared to glutamate while the other two PAMs do not show differences in efficacy between these two agonists. These studies suggest that mGlu7 can be differentially regulated by various agonists and PAMs and provide insight into considerations for chemical optimization campaigns to generate new allosteric ligands for the receptor.
Evaluation of the protein cross‐link breaking effect of selected medicinal plants used in the management of diabetes mellitus
Authors: Adeniran Oluwaseyefunmi I. , Gololo Stanley S. 
Published: May 2022

One of the strategies proposed for combating advanced glycation end‐products (AGEs) and its devastating effects is the breaking of preformed AGEs‐protein cross‐links. AGEs are linked to the pathogenesis of late onset complications of diabetes mellitus, age‐related and neurodegenerative diseases.This study evaluated the AGEs‐protein cross‐link breaking effect of some medicinal plants used for managing diabetes mellitus. These plants, selected based on their blood glucose lowering property, include Sclerocarya birrea, Psidium guajava, Murraya koenigiiand Cinnamon cassia.Of the selected plants, the highest AGEs‐protein cross‐link breaking effect was observed with the hexane and ethyl acetate leaf extracts of Psidium guajava.Methanol extracts of both Psidium guajava leaf and Sclerocarya birrea stem‐bark also showed high cross‐link breaking effect. Chemical screening tests for the presence of phytochemicals and Gas Chromatography Mass Spectrometry (GC‐MS) analysis for the detection and identification of the phytoconstituents in the extracts were also carried out.Compounds detected in the hexane leaf extract of Psidium guajava, using GC‐MS, include I‐(+)‐Ascorbic acid 2,6‐dihexadecanoate, Octadecanoic acid (Stearic acid), Vitamin E (D‐alpha‐tocopherol), Alpha‐Tocopherol‐beta‐D‐mannoside and 2,6,10,14,18,22‐Tetracosahexaene, 2,6,10,15,19,23‐hexamethyl‐, (all‐E) (Squalene). The hexane leaf extract of Psidium guajava was subjected to column chromatography. Using Nuclear Magnetic Resonance and Infra‐red spectroscopy, the isolated compound from the hexane leaf extract of Psidium guajava was identified as a flavonoid.The results of the study indicate that present in these extracts are potent agents with the ability to break AGEs‐protein cross‐links which could be exploited for drug discovery.
Dishevelled localization and function are differentially regulated by structurally distinct sterols
Authors: Sengupta Sonali , Freel Bethany , Francis Kevin 
Published: May 2022

Aberrant cholesterol synthesis, characterized by depletion of cellular cholesterol and accumulation of sterol precursors, is directly linked to a group of rare human diseases exhibiting broad clinical phenotypes and developmental malformations. Despite decreased cholesterol content being shared across these diseases, patients exhibit distinct clinical manifestations associated with specific tissues or systems with varying degrees of phenotypic overlap. This tissue specificity may result from disease‐specific disruption of important critical signaling pathways due to the inability of sterol precursors to structurally compensate for cholesterol. We previously determined that the cholesterol precursor 7‐dehydrocholesterol (7DHC), which accumulates in Smith‐Lemli‐Opitz syndrome, perturbs Dishevelled 2 (DVL2) protein function due to reduced binding affinity of 7DHC to DVL2’s PDZ domain (Postsynaptic density 95, Disc large 1, and Zonular occludens 1 domain) in comparison to cholesterol, resulting in loss of canonical Wnt/β‐catenin signaling (1). We hypothesized that structural differences between cholesterol and alternative sterols will inhibit binding with DVL2 and other PDZ‐domain containing proteins, producing dire cellular consequences and directly affecting Wnt signaling (2). Protein homology modeling and ligand‐protein docking analysis suggested a differential binding affinity and specificity of DVL2 for cholesterol versus alternative sterols. Using PM‐mimetic vesicles incorporating cholesterol versus alternative sterols in liposome/DVL2 pulldowns, we experimentally observed a reduced binding affinity between DVL2 and alternate sterols. Surface plasmon resonance analysis to define the kinetics of protein‐sterol interaction corroborates in silicomodeling and pulldowns. Our data suggests orientation of the beta‐ and alpha‐sterol face within the DVL2‐PDZ domain binding pocket is predictive of DVL2‐sterol interaction. At the cellular level, we have also observed disruption of DVL2‐sterol binding shifts the subcellular localization of DVL2 from the plasma membrane to the nucleus. Increased nuclear DVL2 promotes non‐canonical WNT signaling and DVL2 protein‐protein binding with nuclear factors. Our work suggests that disrupted sterol homeostasis broadly impacts cellular signaling in a sterol‐specific and pathway‐specific manner. Defining the structural and biochemical requirements for sterol interactions with DVL2 and other cholesterol‐binding proteins will help define the critical role sterol homeostasis plays in human health.(1)Francis KR et al, Nature medicine. 2016;22(4):388‐96.(2) Sheng R et al, Nature communications. 2012;3:1249.
An endogenous polyunsaturated fatty acid, dihomo‐gamma‐linoleic acid, induces neurodegeneration in C. elegans via ferroptosis
Authors: Lee Kin Sing Stephen , Sarparast Morteza , Zhang Fan , Seyedehelham Pourmand , Gonzalez Roland E. , Kessler Benjamin , Heasman Benjamin , Alan Jamie 
Published: May 2022

Ferroptosis, an iron‐dependent non‐apoptotic programmed cell death, becomes a novel target and mechanism for age‐associated neurodegenerative diseases. Although several ferroptosis regulatory proteins have been identified, the signaling molecules and the pathways of ferroptosis remain largely unknown. Despite membrane lipid peroxidation being one of the molecular hallmarks of ferroptosis, how polyunsaturated fatty acids (PUFAs) involved in the ferroptosis pathway is understudied. Here, we hypothesize that a specific PUFA and/or its downstream metabolites are lipid mediators of ferroptosis. However, it is challenging to identify by which metabolites regulate ferroptosis and to study the associated mechanism due to many different endogenous PUFAs are presented endogenously and each PUFAs can be metabolized to almost a hundred of metabolites.To take on these challenges, we employed Caenorhabditis elegans (C. elegans) as a novel biological model due to the availability of many genetic and imaging tools, conserved ferroptosis pathways between mammal and C. elegans, and adaptability for high‐throughput whole animal aging study. Using the well‐established fluorescent imaging assay in C. elegans, we showed that treatment of dihomo‐gamma‐linoleic acid (DGLA), but not other PUFAs, induces significant (>40% as compared to control) degeneration in dopaminergic neurons immediately after 1 day of treatment. We also found that treatment of DGLA does not affect other somatic tissues of the C. elegans. Our lipidomic analysis demonstrated that DGLA is well‐absorbed by C. elegans. Besides, our results indicated that DGLA triggers neurodegeneration in dopaminergic neurons, likely through ferroptosis. Using our oxidized lipid metabolites analysis and synthetic chemical probes, we revealed that DGLA likely triggers neurodegeneration viatheir oxidized metabolites. Finally, we will also present the potential ferroptosis signaling pathways triggered by DGLA based on our RNA‐seq experiments.Our results will help us identify novel lipid mediators for ferroptosis, which will lead to a better understanding of the molecular mechanism of ferroptosis. Our findings regarding the neuronal specific effects triggered by DGLA also revive a novel cell‐specific regulatory mechanism of ferroptosis. Lastly, our study will find novel therapeutic targets for either preventative treatment or cure for neurodegenerative diseases.
The effect of the linker in urea‐based soluble epoxide hydrolase inhibitors’ on their blood‐brain penetration ability and drug‐like properties
Authors: Lee Kin Sing Stephen , Prahalad Keshav , Giletto Matthew , Maghami Katayoon , Dickson Alex , Ellsworth Edmund 
Published: May 2022

Soluble epoxide hydrolase (sEH) is a novel therapeutic target for the treatment neurodegenerative diseases, including Parkinson’s disease and Alzheimer’s disease. Although many sEH inhibitors exhibit sub‐nanomolar potency, they suffer from poor blood‐brain barrier penetration and drug‐like properties. As high in vivolevel is required to achieve clinical efficacy for sEH inhibitors for other therapeutic applications, low CNS penetration represents a significant barrier for success for CNS diseases. Therefore, sEH inhibitors with high blood‐brain barrier penetration are needed.Although significant structure‐activity relationships (SAR) have been reported, little data exist exploring the features that overcome the blood‐brain barrier. Most SAR studies have focused on terminal substitutions on both ends of the reported inhibitors with little focus on the “linker” or core of the inhibitors. In this presentation, we will show how the “linker” of urea‐based sEH inhibitors affects their potency, physical properties, and ability to penetrate the blood‐brain barrier. Based on our computational model and the crystal structure of our lead compound, we have prepared new sEH inhibitors with linker containing various ring sizes, bicyclic structures, and simple methyl or fluorine substituents. Perhaps not unexpectantly, the linker of sEH inhibitors has substantial effects on the inhibitor’s potency, solubility, and blood‐brain barrier penetration. In some cases, we observed an increase in blood‐brain penetration by 4‐fold and improvements in solubility by almost 10‐fold. In addition, unexpectedly, our data provides new insights that the linker of the sEH inhibitor affects the binding kinetics without improving the potency of the inhibitors. Our results will create a new direction for the design of novel sEH inhibitors, and we are in the process of leveraging the existing SAR to create much‐improved sEH inhibitors to treat neurodegenerative diseases.
Middle Cerebral Artery Pulsatility Index is Elevated in Chronic Kidney Disease
Authors: Jones Touré , Sprick Justin , DaCosta Dana , Park Jeanie 
Published: May 2022

IntroductionCKD patients exhibit an increased risk of cerebrovascular disease such as stroke, transient ischemic attacks, and cerebral small vessel disease. One mechanism that may contribute to this risk is increased cerebrovascular stiffness and augmented pulsatility of blood flow into the cerebral microcirculation. Middle cerebral artery pulsatility index (MCA PI) provides an indirect measure of cerebrovascular stiffness and can be measured with transcranial Doppler (TCD) ultrasonography. Prior work suggests that MCA PI is elevated in CKD patients following stroke, but it remains unclear if MCA PI is elevated in CKD patients without a history of cerebrovascular disease. Moreover, whether MCA PI correlates with central (aortic) arterial stiffness in CKD remains unknown. We hypothesized that MCA PI would be elevated in CKD patients stages III‐IV compared to controls without CKD matched for age, race, sex, diabetes and hypertension. Furthermore, we hypothesized that MCA PI would correlate with central arterial stiffness and estimated glomerular filtration rate (eGFR) in CKD.Methods13 CKD participants stages III‐IV (mean eGFR=38±3 ml/min/1.73m2) and 10 controls without CKD (age=60±2y) underwent measurement of middle cerebral artery blood velocity via TCD during 5 minutes of seated rest. MCA PI was averaged over the 5 minute period and calculated as MCA PI = (peak systolic blood velocity – diastolic blood velocity)/(mean blood velocity). In CKD, central arterial stiffness was measured via carotid‐femoral pulse wave velocity (cfPWV) after 5 minutes of supine rest. MCA PI was compared between CKD vs CON via 2‐tailed, independent sample T‐tests and the relationships between MCA PI, cfPWV, and eGFR CKD were examined via linear regression.ResultsMCA PI was elevated in CKD compared to CON (0.91±0.06 vs 0.73±.04, P=0.04) and was associated with cfPWV (R=0.72, P=0.01). However, we observed no relationship between MCA PI and eGFR in CKD (P=0.83).DiscussionIn support of our hypothesis, MCA was elevated in CKD compared to controls and was associated with central arterial stiffness. These findings suggest that cerebrovascular stiffness is elevated in CKD patients without a history of cerebrovascular disease, and that MCA PI correlates with central arterial stiffness in CKD. Increases in cerebrovascular stiffness and subsequent flow pulsatility may comprise one mechanism of cerebrovascular disease risk in CKD. Future work should clarify the relationship between MCA PI and severity of renal disease in a larger cohort, and examine the prognostic value of MCA PI as a predictor of future cerebrovascular disease burden in CKD.
Developing A Reference Charts for Foetal Biometry in Indian Population to Predict Growth & Development of Foetus
Authors: Agrawal Dushyant , Mishra Sanjay , Ghatak Surajit , Singh Pratibha , Garg Pawan K. 
Published: May 2022

ObjectivesThe objective of the study was to develop reference charts for foetal abdominal circumference and femur length in normal singleton pregnancies. The modality used in the study was by means of ultrasonography which is easily available and safe during the pregnancy.MethodIn this study, we conducted ultrasonography examination in 300 singleton pregnant women coming for routine checkups. Out of various foetal biometric parameters abdominal circumference (AC) and femur length (FL) were measured and reference charts (10th, 50th, 90th and 95th percentiles) for each parameter corresponding to its gestational age were developed.ResultsAge distribution of pregnant women was uniform (p=0.87). Both parameters i.e. AC and FL were found to be in linear correlation with the corresponding gestational age in weeks. Therefore, their use in determining development and age of the foetus is reliable. We compared our reference charts with other studies conducted in European and Chinese population. From which, it is obvious that the data found in Indian population is different from studies conducted in other ethnic population.ConclusionReference charts derived in this study can be used to determine growth and development of foetus depending upon Indian standards. Because ethnicity, race, nutritional and environmental factors are known to impact the foetal development. Most of the health care set ups are using data from the studies conducted in western population. Which may cause misrepresentation of data in diagnosis. Thus can lead to unnecessary medical intervention which may cause burden in limited resources in developing nations like India. Therefore, we conclude that each population should have their own reference charts for foetal biometry.
Vascular Function Curve: Confusion and Clarification
Authors: Ko Michael Y. , Yang Xiaoqi , ElSayed Suzan , Kuang Serena Y. 
Published: May 2022

IntroductionThe vascular function curve (VFC), cardiac function curve (CFC), and their combination are widely introduced in medical physiology. However, teaching and learning this content is difficult because of a lack of essential information about the independent and dependent variables (IV and DV respectively) of the VFC, which often leads to contradictory interpretations of the combination of the 2 curves. Hence, the goals of this presentation are the following: 1) Describe the origin of the confusion and clarify the confusion in physiology education. 2) Show how the content is inconsistently presented in physiology textbooks and other resources.MethodLiterature review, logical reasoning, and graphical illustration.Results and Discussion1) The origin of the problem and its clarification.The VFC was first plotted and combined with the CFC by Guyton et al. in the 1950s and it describes the relationship between the steady‐state blood flow (i.e., cardiac output (CO)/venous return (VR) in steady‐state) and the right atrial pressure (RAP). Guyton et al. originally plotted the RAP in the X‐axis and the CO/VR in the Y‐axis (Fig. 1A) implying that the RAP is the IV. If the RAP is the IV, the interpretation of the combination of the VFC and CFC is problematic: How does a change in the RAP result in opposite effects on the CO simultaneously (Fig. 1C)? Levy (1979) simplified Guyton et al.’s original experimental setting and argued that the CO in the Y‐axis is the true IV as the pumping rate (CO) was left as the only manipulated variable. Levy also addressed that Guyton’s presentation of the VFC with the RAP on the X‐axis goes against convention. Levy’s clarification is supported by Beard and Feigl in their 2011 article. Despite Levy’s clarification, it is still difficult to interpret the communication of the VFC and CFC: How can the RAP be the IV of the CFC and the DV of the VFC simultaneously? No textbooks provide a convincing explanation to this question and the presentation of the IV and DV of the VFC is inconsistent in the physiology textbooks. 2) The Inconsistent IV and DV of the VFC in textbooks. A total of 9 textbooks and Board review books were reviewed regarding how the IV and DV of the VFC. Eight of them introduced the VFC and CFC (Table 1), were only 2 books described that RAP is the DV.Conclusions1) Levy's clarification of the problem many decades ago has not been well known, so the problem is still prevalent in the circle of physiology education. 2) If the VFC must be taught, the IV and DV of the VFC should be taught consistently in the textbooks.<img src=“https://lh4.googleusercontent.com/nyq5MnJ1mZCmY3yBS1‐kZ7XUqT00hEuMvlpoxr9tl03SvkOr4OLWOLTYbVBOHv7wbVRVscQfJvvAcWnEOxoNwwxsNGjpjw5Sj8jWjLTYiLi6cE‐NqLbqc3OA10j9fP3dPSTbz‐k=s1600” width=“624” height=“180” style=“width: 652.277px; height: 200.125px;”>Fig. 1. Vascular function curve (VFC, 1A), cardiac function curve (CFC, 1B), and their combination (1C) with the independent variable in red and dependent variable in blue in 1A and 1B
Elevated 5‐hydroxytryptamine in COVID‐19 Stimulates ANO1 Mediated Cl Secretion in Lung & Intestinal Epithelial Cells
Authors: Hoque Kazi M. , Hayashi Mikio , Sheikh Irshad A. , Banerjee Aditi , Verma Subhash C. , Leblanc Normand , Zeiss Caroline J. , Ameen Nadia , Chakraborty Subhra 
Published: May 2022

Earlier studies demonstrated that blood 5‐hydroxytryptamine (5‐HT) is elevated in patients with COVID‐19‐associated diarrhea with higher severity of symptoms. We hypothesize that disruption of vectorial Cl transport by 5‐HT may be critical in determining the alveolar flooding and abnormalities in intestinal Cl secretion through stimulation of anoctamin 1(ANO1) Cl channel. Using western blot, immunostaining, and electrophysiology, we characterized the localization of human ANO1 and its stimulation by 5‐HT on Cl secretion in lung and intestinal epithelium. Because calcium‐activated chloride current in human intestinal epithelia remains controversial, we examined the localization of ANO1 in the human terminal ileum and colonic tissue using confocal microscopy. Our results indicated that ANO1 was localized predominantly at the brush‐border membrane and co‐localized with the brush‐border membrane marker villin. ANO1 is not present in goblet cells. The anti‐ANO1 antibody recognized a protein of appropriate size in human colonic tissue. The specificity of the ANO1 antibody was tested by immunoblot analysis of lysates from human colorectal cancer tissues, where it displayed amplified ANO1 protein expression. We next confirmed ANO1‐currents activated by 5‐HT in the Caco‐2 cells by patch‐clamp measurements of whole‐cell current. The application of 100 nM 5‐HT produced a typical outward rectification. CaCCinh‐A01, a specific ANO1 blocker, inhibited the currents. The half‐maximal effective concentration value for the effects of 5‐HT was estimated at 21.8 ± 13.7 nM with a Hill coefficient of 0.89 ± 0.16. These results indicated that 5‐HT evoked calcium‐activated Cl currents through ANO1 channels. ANO1 is expressed in Calu 3 cells. We next confirmed the presence of ANO1 currents activated by 5‐HT in Calu‐3 cells by the Ussing chamber experiments. Serosal addition of 5‐HT produced an immediate and significant increase in Isc in Calu‐3 cells that was inhibited by the ANO1 selective inhibitor T16Ainh‐A01. Finally, we demonstrate that SARS‐CoV2 infection led to enterochromaffin cell hyperplasia in the intestinal epithelium of Syrian Hamster with a possible elevation of 5‐HT, which could explain the severity of symptoms in COVID‐19 associated diarrheal patients.In conclusion, SARS‐CoV2 infection resulted in intestinal enterochromaffin cells hyperplasia that could elevate 5‐HT. Elevated 5‐HT activates luminal ANO1 CaCC in the intestinal and lung epithelium by a mechanism that appears to involve the rise of [Ca2+]i. Our data suggest that 5‐HT may be a critical determinant of the COVID‐19 associated diarrhea and flooding of alveoli that have considerable implications for COVID‐19 therapy.