Metabolic Clearance Research Articles

Status of heavy metals and metalloid concentrations in water resources and associated health risks in parts of Indo-Gangetic plain, India

Groundwater is a major source for the supply of water for drinking as well as supporting the industrial and irrigation demands in the urban and peri-urban regions of Shahjahanpur, Uttar Pradesh, India. However, the groundwater quality of the area is deteriorating due to rapid urbanization, industrialization and intensive agriculture. The present study investigates the heavy metal(loid)s pollution in surface and groundwater and the associated health risks to the inhabitants. The results revealed that most of the analyzed heavy metal(loid)s remained within the acceptable limits set by the Bureau of Indian Standards (BIS, 2012) except for As, Fe, Mn and Ni. The collective impact of heavy metals on water quality was assessed using heavy metal pollution index (HPI) which revealed low pollution in November 2018 and low to medium pollution in October 2021. Ficklin-Caboi plot indicates that metals fall in ‘low’ to ‘high’ classes and their mobility in 30% and 45% of groundwater samples in November 2018 and October 2021 respectively was comparatively higher in the aqueous phase due to slightly lower pH conditions. The evaluated Non-Carcinogenic Hazard Index (HI) was significantly higher than the threshold limit (>1) for children as compared to adults. Relatively higher hazard quotient of As over Fe, Mn and Ni revealed its maximum contribution to the hazard index. The total carcinogenic risk values also exceeded the prescribed acceptable limit (1 × 10−4) for children compared to adults. The greater vulnerability of children can be attributed to several factors such as higher water consumption per unit of body weight of children compared to adults; toxicokinetic differences, immature metabolic enzyme systems and clearance mechanisms that result in longer half-lives of contaminants. Overall, the study reveals an escalated concern regarding heavy metal(loid)s induced health risk and recommends the adoption of conventional techniques for the removal of these metals from water resources.

Transfer learning enhanced graph neural network for aldehyde oxidase metabolism prediction and its experimental application

Aldehyde oxidase (AOX) is a molybdoenzyme that is primarily expressed in the liver and is involved in the metabolism of drugs and other xenobiotics. AOX-mediated metabolism can result in unexpected outcomes, such as the production of toxic metabolites and high metabolic clearance, which can lead to the clinical failure of novel therapeutic agents. Computational models can assist medicinal chemists in rapidly evaluating the AOX metabolic risk of compounds during the early phases of drug discovery and provide valuable clues for manipulating AOX-mediated metabolism liability. In this study, we developed a novel graph neural network called AOMP for predicting AOX-mediated metabolism. AOMP integrated the tasks of metabolic substrate/non-substrate classification and metabolic site prediction, while utilizing transfer learning from 13C nuclear magnetic resonance data to enhance its performance on both tasks. AOMP significantly outperformed the benchmark methods in both cross-validation and external testing. Using AOMP, we systematically assessed the AOX-mediated metabolism of common fragments in kinase inhibitors and successfully identified four new scaffolds with AOX metabolism liability, which were validated through in vitro experiments. Furthermore, for the convenience of the community, we established the first online service for AOX metabolism prediction based on AOMP, which is freely available at https://aomp.alphama.com.cn.

THU397 Homeostatic Regulation Of 1,25-dihydroxyvitamin D: Critical Role Of 24-hydroxylation (CYP24A1)

Abstract Disclosure: Z. Shahidzadeh Yazdi: None. E.A. Streeten: Grant Recipient; Self; Regeneron Pharmaceuticals. H.B. Whitlatch: Grant Recipient; Self; Regeneron Pharmaceuticals. M.E. Montasser: Grant Recipient; Self; Regeneron Pharmaceuticals. A.L. Beitelshees: None. S.I. Taylor: Consulting Fee; Self; Ionis Pharmaceuticals Inc. The VITAL study raised substantial questions whether current Endocrine Society guidelines provide optimal criteria to identify patients whose bone health would benefit from vitamin D (VitD) supplements. We investigated the impact of VitD supplements on levels of VitD metabolites and other biomarkers in the context of studying interactions between VitD and canagliflozin. 11 healthy Amish participants with 25-hydroxyvitamin-D (25(OH)D) levels ≤20 ng/mL were recruited in the context of our ongoing pharmacogenomic study of canagliflozin. RESULTS: VitD supplements increased mean levels of 25(OH)D from 16.5±1.6 ng/mL to 44.3±5.5 ng/mL (p=0.0006) and 24,25(OH)2D from 1.0±0.1 ng/mL to 4.3±0.6 ng/mL (p=0.0002). Mean levels of 1,25(OH)2D and PTH were unchanged: 43.8±3.6 vs. 44.9±4.1 pg/mL for 1,25(OH)2D and 47.5±4.8 vs. 48.4±5.1 pg/mL for PTH. We applied mathematical modeling, which suggested that regulation of 24-hydroxylation was the principal mechanism responsible for maintaining 1,25(OH)2D levels within a narrow range in our mildly VitD deficient research participants [25(OH)D levels: 10-20 ng/mL]. When 25(OH)D levels were low (<20 ng/mL), 24-hydroxylation was maximally suppressed. Low levels of 24-hydroxylase activity tend to sustain levels of 1,25(OH)2D by decreasing its rate of metabolic clearance. VitD supplementation induced 24-hydroxylase activity by ∼5-fold – reaching a plateau when 25(OH)D levels >60 ng/mL. As suggested in the literature (JCY Tang et al, Sci Rep, 9:6974, 2019), we calculated ratios of 1,25(OH)2D/24,25(OH)2D as an index for the homeostatic response to VitD status. When we plotted the 1,25(OH)2D/24,25(OH)2D ratio as a function of 25(OH)D/1,25(OH)2D, we observed an extremely high degree of correlation (Spearman correlation coefficient of -0.94; p=10-10). DISCUSSION: Clinical assessment of thyroid status provides a highly relevant historical precedent. 50 years ago, thyroid status was assessed by measurement of total serum thyroxine (T4) levels. Diagnostic accuracy was greatly improved when total T4 was replaced by laboratory measurement of either free T4 or TSH (an index of the homeostatic response to thyroid status). Current clinical guidelines recommend assessment of VitD status by measuring total levels of 25(OH)D, which unfortunately are confounded by inter-individual variation in levels of VitD binding proteins (VDBP). We anticipate that diagnostic accuracy would be greatly enhanced if clinicians replaced measurement of total 25(OH)D by laboratory measurements that are not affected by variation in levels of VDBP. By analogy to the approach to clinical assessment of thyroid status, we recommend consideration of VDBP-independent indices of VitD status including 25(OH)D/1,25(OH)2D as an index of VitD stores and 1,25(OH)2D/24,25(OH)2D as an index for the body’s homeostatic response to VitD status. Presentation: Thursday, June 15, 2023

Plasma Aβ level alterations after sleep deprivation correspond to brain structural remodeling in medical night shift workers

The relationship between brain structure alteration and metabolic product clearance after night shift work with total sleep deprivation (SD) remains unclear. Twenty-two intensive care unit staff on regularly rotating shift work were implemented with structural and diffusion MRI under both rest wakefulness (RW) and SD conditions. Peripheral blood samples were collected for the measurement of cerebral metabolites. Voxel-based morphometry and diffusion tensor imaging analysis were used to investigate the alterations in the gray matter density (GMD) and mean diffusivity (MD) within the participants. Furthermore, correlation analysis was performed to investigate the relationship between the neuroimaging metrics and hematological parameters. A significant increase in the GMD values was observed in the anterior and peripheral areas of the brain under SD. In contrast, a decrease in the values was observed in the posterior regions, such as the bilateral cerebellum and thalamus. In addition, a significant reduction in the total cerebrospinal fluid volume was observed under SD. The Aβ42/Aβ40 levels in participants under SD were significantly lower than those under RW. The mean MD increment values extracted from the region of interest (ROI) of the anterior brain were negatively correlated with the increment of plasma Aβ42/Aβ40 levels (r = −0.658, P = 0.008). The mean GMD decrement values extracted from the posterior ROI were positively correlated with the increment of plasma Aβ-40 levels (r = 0.601, P = 0.023). The findings of this study suggest that one night of shift work under SD induces extensive and direction-specific structural alterations of the brain, which are associated with aberrant brain metabolic waste clearance.

Design, synthesis, and biological evaluation of a novel series of 1,2,4-oxadiazole inhibitors of SLACK potassium channels: Identification of in vitro tool VU0935685

Malignant migrating partial seizure of infancy (MMPSI) is a devastating and pharmacoresistant form of infantile epilepsy. MMPSI has been linked to multiple gain-of-function (GOF) mutations in the KCNT1 gene, which encodes for a potassium channel often referred to as SLACK. SLACK channels are sodium-activated potassium channels distributed throughout the central nervous system (CNS) and the periphery. The investigation described here aims to discover SLACK channel inhibitor tool compounds and profile their pharmacokinetic and pharmacodynamic properties. A SLACK channel inhibitor VU0531245 (VU245) was identified via a high-throughput screen (HTS) campaign. Structure-activity relationship (SAR) studies were conducted in five distinct regions of the hit VU245. VU245 analogs were evaluated for their ability to affect SLACK channel activity using a thallium flux assay in HEK-293 cells stably expressing wild-type (WT) human SLACK. Selected analogs were tested for metabolic stability in mouse liver microsomes and plasma-protein binding in mouse plasma. The same set of analogs was tested via thallium flux for activity versus human A934T SLACK and other structurally related potassium channels, including SLICK and Maxi-K. In addition, potencies for selected VU245 analogs were obtained using whole-cell electrophysiology (EP) assays in CHO cells stably expressing WT human SLACK through an automated patch clamp system. Results revealed that this scaffold tolerates structural changes in some regions, with some analogs demonstrating improved SLACK inhibitory activity, good selectivity against the other channels tested, and modest improvements in metabolic clearance. Analog VU0935685 represents a new, structurally distinct small-molecule inhibitor of SLACK channels that can serve as an in vitro tool for studying this target.

Long cruising aptamer-albumin nanobots intelligently capture and restrain circulating tumor cells

Circulating tumor cells (CTC) are the root cause of life-threatening cancer metastases. The rare CTC cannot be specifically killed by anti-cancer agents without producing any side effects, nor be targeted-and-eradicated by antibody or aptamer complexes because of the complexes’ limited circulating half-life in the blood owing to metabolism and immune clearance. Here, we build the biosafe and biostable aptamer-albumin nanobots that can cruise in the blood much long together with the CTC, resulting in the increased capture efficiency and specificity of the nanobots targeting CTC. The intelligent-recognizing unit of the novel nanobots is composed of three EpCAM-targeting aptamers (AP) that can specifically target breast CTC, and their sticky ends are completely closed to form the biostable circular trivalent aptamers (CTA). The binding energy, specificity and stability of the circular three arms CTA are significantly superior to their linear AP. After conjugating CTA to human serum albumin (CTA-HSA) by amination reaction, the blood circulation time of CTA-HSA in mice was significantly prolonged by 3 folds, resulting in the enhanced collision probability and increased capture efficiency of CTA-HSA to CTC. CTA-HSA can escape the immune clearance and inhibit adhesion/invasion and cell cycle of CTC, resulting in CTC apoptosis. This proof-of-concept study provides a promising nanobiomaterial for CTC-induced cancer metastases.

CSF-to-blood toxins clearance is modulated by breathing through cranio-spinal CSF oscillation.

Clearance of brain toxins occurs during sleep, although the mechanism remains unknown. Previous studies implied that the intracranial aqueductal cerebrospinal fluid (CSF) oscillations are involved, but no mechanism was suggested. The rationale for focusing on the aqueductal CSF oscillations is unclear. This study focuses on the cranio-spinal CSF oscillation and the factors that modulate this flow. We propose a mechanism where increased cranio-spinal CSF movements enhance CSF-to-blood metabolic waste clearance through the spinal CSF re-absorption sites. A recent study demonstrating that disturbed sleep impairs CSF-to-blood but not brain-to-CSF clearance, supports the fundamentals of our proposed mechanism. Eight healthy subjects underwent phase-contrast magnetic resonance imaging to quantify the effect of respiration on the cranio-spinal CSF oscillations. Maximal CSF volume displaced from the cranium to the spinal canal during each respiration and cardiac cycle were derived as measures of cranio-spinal CSF mixing level. Transition from normal to slow and abdominal breathing resulted in a 56% increase in the maximal displaced CSF volume. Maximal change in the arterial-venous blood volume, which is the driving force of the CSF oscillations, was increased by 41% during slow abdominal breathing. Cranio-spinal CSF oscillations are driven by the momentary difference between arterial inflow and venous outflow. Breathing modulates the CSF oscillation through changes in the venous outflow. The amount of toxins being transferred to the spinal canal during each respiratory cycle is significantly increased during slow and deeper abdominal breathing, which explains enhanced CSF-to-blood toxins clearance during slow-wave sleep and poor clearance during disrupted sleep.

The in vitro metabolism of GMDTC in liver microsomes of human, monkey, dog, rat and mouse: Metabolic stability assessment, metabolite identification and interspecies comparison

Sodium (S)− 2-(dithiocarboxylato((2 S,3 R,4 R,5 R)− 2,3,4,5,6-pentahydroxyhexyl)amino)− 4(methylthio)butanoate (GMDTC) is a compound that removes cadmium from kidney cells. This study aims to investigate the metabolic stability and metabolite identification of GMDTC in various liver microsomes, including those from human, monkey, dog, rat and mouse. The results show that the T1/2 values of GMDTC in human, monkey, dog, rat and mouse liver microsomes were 16.54, 18.14, 16.58, 15.16 and 16.00 min, respectively. While the hepatic extraction ratios (ERh) of GMDTC measured after 60 min incubation in these liver microsomes were 0.82, 0.70, 0.80, 0.75 and 0.79, respectively, indicating that GMDTC exhibits rapid hepatic metabolism and high hepatic clearance with no significant interspecies differences. Subsequent metabolite identification by high-resolution mass spectrometry revealed the presence of three metabolites, designated M1∼M3. The major metabolite products of GMDTC were found to be M1 and M2. The relative abundances of the hydrolysis products (M1 and M2) in human, monkey, dog, rat and mouse liver microsomes were found to be 97.18%, 97.99%, 95.94%, 96.31% and 93.43%, respectively, indicating that hydrolysis is the primary metabolic pathway of GMDTC in liver microsomes in vitro, and with no significant interspecies differences.

Modelling the Effect of the Exposure to Perfluorooctanoate (PFOA) and Perfluorooctane Sulfonate (PFOS) on Thyroid Homeostasis

Thyroid homeostasis is crucial for the human body. The imbalance of thyroid homeostasis might cause diseases such as hypothyroidism. Humans are exposed to PFOS/PFOA frequently since they have been used in various industrial products. As reported that PFOS/PFOA increase the metabolic clearance rate of thyroid hormones, we then develop a mathematical model in terms of a system of differential equations to investigate thyroid homeostasis based on the changes in the levels of thyrotropin-releasing hormone, thyroid-stimulating hormone and thyroid hormones when the effect of the exposure to PFOS and PFOA is also incorporated as well. The geometric singular perturbation technique is then employed to identify the possible dynamic behaviours obtained from the model. Numerical investigations are also presented to illustrate the results from theoretical analysis. Both theoretical and numerical results imply that a periodic behaviour that has been observed clinically in the pulsatile secretions of thyroid hormones, thyroid-stimulating hormone and thyrotropin-releasing hormone could be obtained from our model. In addition, the numerical experiment also shows that the levels of thyroid hormones and thyroid-stimulating hormone for the case when there is the effect of exposure to PFOS and PROA are lower than those of the case when there is no effect of the exposure to PFOS and PFOA which might lead to the imbalance of thyroid homeostasis.

Oxetanes in Drug Discovery Campaigns.

The oxetane ring is an emergent, underexplored motif in drug discovery that shows attractive properties such as low molecular weight, high polarity, and marked three-dimensionality. Oxetanes have garnered further interest as isosteres of carbonyl groups and as molecular tools to fine-tune physicochemical properties of drug compounds such as pKa, LogD, aqueous solubility, and metabolic clearance. This perspective highlights recent applications of oxetane motifs in drug discovery campaigns (2017-2022), with emphasis on the effect of the oxetane on medicinally relevant properties and on the building blocks used to incorporate the oxetane ring. Based on this analysis, we provide an overview of the potential benefits of appending an oxetane to a drug compound, as well as potential pitfalls, challenges, and future directions.

Oleoylethanolamide facilitates PPARα and TFEB signaling and attenuates Aβ pathology in a mouse model of Alzheimer’s disease

BackgroundAge is the strongest risk factor for the development of Alzheimer’s disease (AD). Besides the pathological hallmarks of β-amyloid (Aβ) plaques and neurofibrillary tangles, emerging evidence demonstrates a critical role of microglia and neuroinflammation in AD pathogenesis. Oleoylethanolamide (OEA) is an endogenous lipid amide that has been shown to promote lifespan and healthspan in C. elegans through regulation of lysosome-to-nucleus signaling and cellular metabolism. The goal of our study was to determine the role of OEA in the mediation of microglial activity and AD pathology using its stable analog, KDS-5104.MethodsWe used primary microglial cultures and genetic and pharmacological approaches to examine the signaling mechanisms and functional roles of OEA in mediating Aβ phagocytosis and clearance, lipid metabolism and inflammasome formation. Further, we tested the effect of OEA in vivo in acute LPS-induced neuroinflammation and by chronic treatment of 5xFAD mice.ResultsWe found that OEA activates PPARα signaling and its downstream cell-surface receptor CD36 activity. In addition, OEA promotes TFEB lysosomal function in a PPARα-dependent but mTORC1-independent manner, the combination of which leads to enhanced microglial Aβ uptake and clearance. These are associated with the suppression of LPS-induced lipid droplet accumulation and inflammasome activation. Chronic treatment of 5xFAD mice with KDS-5104 restored dysregulated lipid profiles, reduced reactive gliosis and Aβ pathology and rescued cognitive impairments.ConclusionTogether, our study provides support that augmenting OEA-mediated lipid signaling may offer therapeutic benefit against aging and AD through modulating lipid metabolism and microglia phagocytosis and clearance.

Exploring the boundaries for in vitro-in vivo extrapolation: Use of isolated hepatocytes in co-culture and impact of albumin binding properties in the prediction of clearance of various drug types.

Prediction of hepatic clearance of drugs (via uptake or metabolism) from in vitro systems continues to be problematic. This is particularly the case when plasma protein binding is high. The following work explores simultaneous assessment of both clearance processes, focusing on a commercial hepatocyte-fibroblast co-culture system (HµREL), over a 24 hour period, using a series of six probe drugs (ranging in metabolic and transporter clearance and low-to-high plasma protein binding). A rat hepatocyte co-culture prototype assay was established using drug depletion (measuring both medium and total concentrations) and cell uptake kinetic analysis, both in the presence (1 and 4%) and absence of plasma protein (BSA). Secretion of endogenous albumin was monitored as a marker of viability and this reached 0.004% in incubations (at a rate similar to in vivo synthesis). Binding to stromal cells was significant and required appropriate correction factors. Drug concentration-time courses were analysed both by conventional methods and a mechanistic cell model, prior to in vivo extrapolation. CL assayed by drug depletion in conventional suspended rat hepatocytes provided a benchmark to evaluate co-culture value. Addition of albumin appeared to improve predictions for some compounds (where fu<0.1); however, for high binding drugs, albumin significantly limited quantification and thus predictions. Overall, these results indicate the prospect of reliable measurement of hepatically cleared compounds, including (of novelty) those with low metabolic turnover but high active uptake, through the longevity of co-culture systems combined with judicious sampling. Significance Statement Co-culture systems, combining hepatocytes with stromal cells, offer a more advanced tool than standard hepatocytes, with the ability to be cultured for longer periods of time, yet their potential has not been comprehensively assessed. We evaluate the strengths and limitations of the HµREL system via the use of six drugs representing various metabolic and transporter-mediated clearance pathways with various degrees of albumin binding. Studies in the presence and absence of albumin allow IVIVE and a framework to maximise their utility.

Using meta-analysis to explore the roles of global upwelling exposure and experimental design in bivalve responses to low pH

Low pH conditions, associated with ocean acidification, represent threats to many commercially and ecologically important organisms, including bivalves. However, there are knowledge gaps regarding factors explaining observed differences in biological responses to low pH in laboratory experiments. Specific sources of local adaptation such as upwelling exposure and the role of experimental design, such as carbonate chemistry parameter changes, should be considered. Linking upwelling exposure, as an individual oceanographic phenomenon, to responses measured in laboratory experiments may further our understanding of local adaptation to global change. Here, meta-analysis is used to test the hypotheses that upwelling exposure and experimental design affect outcomes of individual, laboratory-based studies that assess bivalve metabolic (clearance and respiration rate) responses to low pH. Results show that while bivalves generally decrease metabolic activity in response to low pH, upwelling exposure and experimental design can significantly impact outcomes. Bivalves from downwelling or weak upwelling areas decrease metabolic activity in response to low pH, but bivalves from strong upwelling areas increase or do not change metabolic activity in response to low pH. Furthermore, experimental temperature, exposure time and magnitude of the change in carbonate chemistry parameters all significantly affect outcomes. These results suggest that bivalves from strong upwelling areas may be less sensitive to low pH. This furthers our understanding of local adaptation to global change by demonstrating that upwelling alone can explain up to 49 % of the variability associated with bivalve metabolic responses to low pH. Furthermore, when interpreting outcomes of individual, laboratory experiments, scientists should be aware that higher temperatures, shorter exposure times and larger changes in carbonate chemistry parameters may increase the chance of suppressed metabolic activity.

Design, synthesis and biological evaluation of chalcone derivatives as potent and orally active hCYP3A4 inhibitors

Human cytochrome P450 3A4 (hCYP3A4), one of the most important drug-metabolizing enzymes, catalyze the metabolic clearance of ∼50% therapeutic drugs. CYP3A4 inhibitors have been used for improving the in vivo efficacy of hCYP3A4-substrate drugs. However, most of existing hCYP3A4 inhibitors may trigger serious adverse effects or undesirable effects on endogenous metabolism. This study aimed to discover potent and orally active hCYP3A4 inhibitors from chalcone derivatives and to test their anti-hCYP3A4 effects both in vitro and in vivo. Following three rounds of screening and structural optimization, the isoquinoline chalcones were found with excellently anti-hCYP3A4 effects. SAR studies showed that introducing an isoquinoline ring on the A-ring significantly enhanced anti-CYP3A4 effect, generating A10 (IC50 = 102.10 nM) as a promising lead compound. The 2nd round of SAR studies showed that introducing a substituent group at the para position of the carbonyl group on B-ring strongly improved the anti-CYP3A4 effect. As a result, C6 was identified as the most potent hCYP3A4 inhibitor (IC50 = 43.93 nM) in human liver microsomes (HLMs). C6 also displayed potent anti-hCYP3A4 effect in living cells (IC50 = 153.00 nM), which was superior to the positive inhibitor ketoconazole (IC50 = 251.00 nM). Mechanistic studies revealed that C6 could potently inhibit CYP3A4-catalyzed N-ethyl-1,8-naphthalimide (NEN) hydroxylation in a competitive manner (Ki = 30.00 nM). Moreover, C6 exhibited suitable metabolic stability in HLMs and showed good safety profiles in mice. In vivo tests demonstrated that C6 (100 mg/kg, orally administration) significantly increased the AUC(0-inf) of midazolam by 3.63-fold, and strongly prolonged its half-life by 1.66-fold compared with the vehicle group in mice. Collectively, our findings revealed the SARs of chalcone derivatives as hCYP3A4 inhibitors and offered several potent chalcone-type hCYP3A4 inhibitors, while C6 could serve as a good lead compound for developing novel, orally active CYP3A4 inhibitors with improved druglikeness properties.

New bysspectin A derivatives as potent inhibitors of human carboxylesterase 2A

Human carboxylesterase 2A (hCES2A), the most abundant carboxylesterase in the human gut, plays a crucial role in the metabolic clearance and activation of various ester-bearing drugs, environmental toxins and carcinogens. Inhibition of intestinal hCES2A can alleviate irinotecan-induced gut toxicity and modulate the oral bioavailability of hCES2A-substrate drugs. Bysspectin A, a natural product isolated from the endophytic fungus Byssochlamys spectabilis, has been identified as a highly selective hCES2A inhibitor. Herein, two sets of bysspectin A derivatives have been designed and synthesized, utilizing a Cu-catalyzed domino Sonogashira-cyclization as the key step. Following two rounds of structure activity relationship (SAR) studies and structural optimizations, compound 20w was identified as the most potent hCES2A inhibitor, with an IC50 value of 1.6 nM, an approximately 1000-fold improvement over bysspectin A. Further investigation showed that 20w potently inhibited hCES2A in a mixed inhibition manner, while this agent could also potently inhibit intracellular hCES2A in living cells and exhibited suitable metabolic stability. In summary, our findings demonstrate that a new bysspectin A derivative (20w) is a promising candidate for the development of clinically used hCES2A inhibitor.

Recent advances in measurement of metabolic clearance, metabolite profile and reaction phenotyping of low clearance compounds

ABSTRACT Introduction Low metabolic clearance is usually a highly desirable property of drug candidates in order to reduce dose and dosing frequency. However, measurement of low clearance can be challenging in drug discovery. A number of new tools have recently been developed to address the gaps in the measurement of intrinsic clearance, identification of metabolites, and reaction phenotyping of low clearance compounds. Areas covered The new methodologies of low clearance measurements are discussed, including the hepatocyte relay, HepatoPac®, HμREL®, and spheroid systems. In addition, metabolite formation rate determination and in vivo allometric scaling approaches are covered as alternative methods for low clearance measurements. With these new methods, measurement of ~ 20-fold lower limit of intrinsic clearance can be achieved. The advantages and limitations of each approach are highlighted. Expert opinion Although several novel methods have been developed in recent years to address the challenges of low clearance, these assays tend to be time and labor intensive and costly. Future innovations focusing on developing systems with high enzymatic activities, ultra-sensitive universal quantifiable detectors, and artificial intelligence will further enhance our ability to explore the low clearance space.

Nano Drug Delivery Strategies for anOral Bioenhanced Quercetin Formulation.

Quercetin, a naturally occurring flavonoid, has been credited with a wide spectrum of therapeutic properties. However, the oral use of quercetin is limited due to its poor water solubility, low bioavailability, rapid metabolism, and rapid plasma clearance. Quercetin has been studied extensively when used with various nanodelivery systems for enhancing quercetin bioavailability. To enhance its oral bioavailability and efficacy, various quercetin-loaded nanosystems such as nanosuspensions, polymer nanoparticles, metal nanoparticles, emulsions, liposomes or phytosomes, micelles, solid lipid nanoparticles, and other lipid-based nanoparticles have been investigated in in-vitro cells, in-vivo animal models, and humans. Among the aforementioned nanosystems, quercetin phytosomes are attracting more interest and are available on the market. The present review covers insights into the possibilities of harnessing quercetin for several therapeutic applications and a special focus on anticancer applications and the clinical benefits of nanoquercetin formulations.

Concepts of Lactate Metabolic Clearance Rate and Lactate Clamp for Metabolic Inquiry: A Mini-Review.

Lactate is known to play a central role in the link between glycolytic and mitochondrial oxidative metabolism, as well as to serve as a primary gluconeogenic precursor. Blood lactate concentration is sensitive to the metabolic state of tissues and organs as lactate rates of appearance and disposal/disappearance in the circulation rise and fall in response to physical exercise and other metabolic disturbances. The highest lactate flux rates have been measured during moderate intensity exercise in endurance-trained individuals who exhibit muscular and metabolic adaptations lending to superior oxidative capacity. In contrast, a diminished ability to utilize lactate is associated with poor metabolic fitness. Given these widespread implications in exercise performance and health, we discuss the concept of lactate metabolic clearance rate, which increases at the onset of exercise and, unlike flux rates, reaches a peak just below the power output associated with the maximal lactate steady state. The metabolic clearance rate is determined by both disposal rate and blood concentration, two parameters that are mutually interdependent and thus difficult to parse during steady state exercise studies. We review the evolution of the in vivo lactate clamp methodology to control blood lactate concentration and discuss its application in the investigation of whole-body lactate disposal capacities. In conclusion, we assert that the lactate clamp is a useful research methodology for examining lactate flux, in particular the factors that drive metabolic clearance rate.

Hydrophilic Copolymers with Hydroxamic Acid Groups as a Protective Biocompatible Coating of Maghemite Nanoparticles: Synthesis, Physico-Chemical Characterization and MRI Biodistribution Study.

Superparamagnetic iron oxide nanoparticles (SPION) with a "non-fouling" surface represent a versatile group of biocompatible nanomaterials valuable for medical diagnostics, including oncology. In our study we present a synthesis of novel maghemite (γ-Fe2O3) nanoparticles with positive and negative overall surface charge and their coating by copolymer P(HPMA-co-HAO) prepared by RAFT (reversible addition-fragmentation chain-transfer) copolymerization of N-(2-hydroxypropyl)methacrylamide (HPMA) with N-[2-(hydroxyamino)-2-oxo-ethyl]-2-methyl-prop-2-enamide (HAO). Coating was realized via hydroxamic acid groups of the HAO comonomer units with a strong affinity to maghemite. Dynamic light scattering (DLS) demonstrated high colloidal stability of the coated particles in a wide pH range, high ionic strength, and the presence of phosphate buffer (PBS) and serum albumin (BSE). Transmission electron microscopy (TEM) images show a narrow size distribution and spheroid shape. Alternative coatings were prepared by copolymerization of HPMA with methyl 2-(2-methylprop-2-enoylamino)acetate (MMA) and further post-polymerization modification with hydroxamic acid groups, carboxylic acid and primary-amino functionalities. Nevertheless, their colloidal stability was worse in comparison with P(HPMA-co-HAO). Additionally, P(HPMA-co-HAO)-coated nanoparticles were subjected to a bio-distribution study in mice. They were cleared from the blood stream by the liver relatively slowly, and their half-life in the liver depended on their charge; nevertheless, both cationic and anionic particles revealed a much shorter metabolic clearance rate than that of commercially available ferucarbotran.

Can Wim Hof Method breathing induce conscious metabolic waste clearance of the brain?

Metabolic waste clearance of the brain is an emerging field of research pertinent to neurodegenerative and psychiatric conditions. Within the past decade, sleep has been identified as a primary factor in terms of waste clearance of the brain via the nasal turbinates and glymphatic system. Disturbances of sleep induced by conditions such as insomnia have been observed to promote multifactorial conditions that contribute to accelerated neurodegeneration and neuroinflammation. In addition, it’s been observed that the medium primarily responsible for brain waste clearance is cerebrospinal fluid (CSF). Recent research indicates that CSF movement is primarily modulated by respiration. Based on the data indicating an inverse relationship between CSF volume and cerebral blood volume (CBV), it brings us to the hypothesis that utilizing Wim Hof Method (WHM) breathing instructions can induce accelerated, conscious waste clearance of the brain. This is based on the inspiration portion of respiration driving CSF into the brain increasing CSF volume while inducing arterial vasoconstriction. Following repetitive deep inspirations, WHM utilizes full exhalation followed by sustained breath retention of 30 s or more. We hypothesize that during this breath retention, cerebral arterial vasodilation takes place increasing CBV therefore displacing CSF by forcing this fluid to drain out via the nasal turbinates and glymphatic system. This would be the first study to date identifying that brain waste clearance can be consciously modulated via a specific respiration technique during our waking state. The ramifications of this research could have important implications for optimal treatment and care plans regarding neurodegenerative diseases.