Endogenous Marker Research Articles

Clove bud (Syzygium aromaticum L.) polyphenol helps to mitigate metabolic syndrome by establishing intracellular redox homeostasis and glucose metabolism: A randomized, double-blinded, active-controlled comparative study

• Influence of Clovinol verses synthetic Glutathione (s-GSH) in metabolic syndrome. • Clovinol enhanced Nrf2 and plasma GSH levels by 6-fold compared to s-GSH. • Clovinol helps balanced intracellular redox homeostasis. • Clovinol modulated glucose and lipid metabolism. • Clovinol may help balanced immunity. Present randomised double-blinded comparative study investigated the influence of clove buds ( Syzygium aromaticum ) polyphenol extract (Clovinol) in comparison with synthetic glutathione (s-GSH) (250 mg/day for 84 days) on healthy adults (N = 70) characterised with metabolic syndrome (MetS). Outcome measures included plasma concentration of endogenous antioxidants, inflammatory markers, blood sugar and lipid metabolism markers, in addition to haematological and biochemical parameters of safety. Clovinol enhanced the plasma concentration of GSH by 6-fold and offered statistically significant enhancement in Nrf2, antioxidant enzymes and in GSH/GSSG ratio. Treatment with Clovinol also improved FBS, PPG, HbA1c, HOMA-IR and insulin levels indicating modulation of insulin resistance. Moreover, Clovinol caused significant reduction in total cholesterol, triglycerides, LDL and increased HDL, while s-GSH showed no significant effect on blood glucose and lipid metabolism. Clovinol did not show any significant side effects or toxic deviations in haematological and biochemical parameters, but significantly increased the total leukocyte and reduced neutrophil/lymphocyte ratio and inflammatory markers (IL-1β and TNF-α).

A comprehensive UHPLC-MS/MS method for the analysis of endogenous and exogenous steroids in serum for anti-doping purposes.

In the context of steroid analyses, the use of blood could represent a valuable complement to urine. While the blood steroid profile is currently being established to aid unveiling testosterone (T) doping, this matrix is also well suited for detection of exogenous anabolic steroids and steroid esters. In this study, a method to determine a simplified blood steroid profile in combination with the direct detection of exogenous anabolic steroids and steroid esters using just one serum aliquot was developed to obtain a comprehensive analytical workflow. Following the first chromatographic analysis of endogenous and exogenous steroids, samples were derivatised with Girard's reagent T (GT) to improve the ionisation of steroid esters and re-injected. The quantitative performance for T, androstenedione (A4) and 5α-dihydrotestosterone (DHT) was evaluated and the method was validated for qualitative analysis of exogenous analogues with estimated limits of detection (LOD) between 50 and 500 pg/ml. To demonstrate the applicability of the method, samples collected from a clinical study with an oral administration of testosterone undecanoate (TU) to 19 male volunteers were then analysed. The individual serum steroid profiles with the endogenous markers T, A4 and DHT were established as well as the concentrations of TU. TU was detected in all 19 volunteers up to 24 h, while DHT represented the most promising biomarker in endogenous steroid profile for the detection of oral TU administration. These results showed that the selected approach to combine exogenous and endogenous steroid analysis has the potential to strengthen T doping detection in the future.

Analysis of results of volatile organic compound (VOC) measurements using breathanalyzer on COVID-19 confirmed patients with pneumonia and without pneumonia

WHO declared COVID-19 infection as a pandemic since 2020. A rapid noninvasive examination is needed for screening and diagnostic. Exhaled Volatile Organic Compound (VOC) is a sample directly connected to the affected organ, which is the lung, and can be measured as an endogenous volatile marker resulted from oxidative stress. This study aims to analyze differences in VOC concentration in COVID-19 patients with pneumonia and without pneumonia. This Case Control Study used 93 confirmed case samples of COVID-19 and 42 healthy subject. Demographic and clinical data taken from anamnesis and/or medical records. VOC’s data of respiratory track are taken through the exhalation air in a bag and analyzed with breathanalyzer. Statistical analysis was conducted using Mann-Whitney test. In the analysis of confirmed samples of COVID-19 between pneumonia and without pneumonia, co components were found to affect the incidence of pneumonia in confirmed samples of COVID-19 (p=0.003). This conclusion is Components of CO in confirmed COVID-19 have a meaningful effect on an event of pneumonia.

Binary Role Theory and Levels of Role Change in World Politics: When Do Leaders Make a Difference?

The problem of understanding when and how change happens in world politics is under-conceptualized. One potential source of change for further examination is the relationship between change and the leadership of states and international institutions. The decisions and actions of leaders are an immediate source of both peaceful and violent change. A change of leaders may simply be an endogenous marker for a shift in historical forces that explain change in world politics, or leaders may be indispensable in explaining change at state and systemic levels of analysis. Are leaders the pilots or simply passengers on states caught in the tides of history? Binary role theory offers a coherent account of “role change”specified by the interactions and outcomes between leaders and historical situations, which is a more nuanced “both/and”account than a simple “either/or”answer to this question. The interactions and outcomes that model role change are first presented in the abstract terms of role theory and then illustrated with two case studies of UK-Iran and US-Iran relations.

Risk assessment of drug-drug interaction potential for bintrafusp alfa with cytochrome P4503A4 substrates: A totality of evidence approach.

Bintrafusp alfa, a first-in-class bifunctional fusion protein composed of the extracellular domain of TGF-βRII (a TGF-β "trap") fused to a human IgG1 mAb blocking PD-L1, is being evaluated for efficacy and safety in solid tumor indications as monotherapy and in combination with small-molecule drugs. We evaluated the perpetrator drug-drug interaction (DDI) potential of bintrafusp alfa via cytochrome P4503A4 (CYP3A4) enzyme modulation, which is responsible for the metabolism of a majority of drugs. The holistic approach included (1) evaluation of longitudinal profiles of cytokines implicated in CYP3A4 modulation and serum 4β-hydroxycholesterol, an endogenous marker of CYP3A4 activity, in a phase I clinical study, and (2) transcriptomics analysis of the CYP3A4 mRNA levels vs the TGFB gene expression signature in normal hepatic tissues. Bintrafusp alfa was confirmed not to cause relevant proinflammatory cytokine modulation or alterations in 4β-hydroxycholesterol serum concentrations in phase I studies. Transcriptomics analyses revealed no meaningful correlations between TGFB gene expression and CYP3A4 mRNA expression, supporting the conclusion that the risk of CYP3A4 enzyme modulation due to TGF-β neutralization by bintrafusp alfa is low. Thus, bintrafusp alfa is not expected to have DDI potential as a perpetrator with co-administered drugs metabolized by CYP3A4; this information is relevant to clinical evaluations of bintrafusp alfa in combination settings.

A Cross-Sectional Measurement of Endogenous Oxidative Stress Marker Levels in Obsessive Compulsive Disorder.

There is a correlation between the increase in reactive oxygen radicals and the presence of specific mental illnesses. In this context, the objective of this study is to investigate the relationship between obsessive-compulsive disorder and the variations in the levels of several endogenous oxidative stress markers. Thirty obsessive-compulsive disorder patients were included in the study as the patient group, and 30 healthy volunteers of matching demographic characteristics were included in the study as the control group. Accordingly, the patient group consisted of 10 females and 20 males with a mean age of 29.5 ± 6.1 years, and the control group consisted of 15 females and 15 males with a mean age of 31.9±5.6 years. The serum nicotinamide adenine dinucleotide phosphate oxidase-2, nicotinamide adenine dinucleotide phosphate oxidase-4, and malondialdehyde levels of the 2 groups were compared using the independent samples t-test. The relationships between the serum nicotinamide adenine dinucleotide phosphate oxidase-2, nicotinamide adenine dinucleotide phosphate oxidase-4, and malondialdehyde levels of the 2 groups were analyzed using the Pearson's correlation coefficient. The serum nicotinamide adenine dinucleotide phosphate oxidase-2, nicotinamide adenine dinucleotide phosphate oxidase-4, and malondialdehyde levels of the patient group were statistically significantly higher than those of the control group (P < .001). Statistically significant positive correlations were detected between the serum nicotinamide adenine dinucleotide phosphate oxidase-2 and nicotinamide adenine dinucleotide phosphate oxidase-4 levels (r = 0.692, P = .001) and between the serum nicotinamide adenine dinucleotide phosphate oxidase-2 and malondialdehyde levels (r = 0.563, P = .001). The results of this study indicated that oxidative stress and lipid peroxidation levels were higher in obsessive-compulsive disorder patients. Based on this finding, NOX-2 and NOX-4 levels can be used as indicators of endogenous oxidative stress in obsessive-compulsive disorder patients.

Estimated Kidney Tubular Secretion and Kidney, Cardiovascular, and Mortality Outcomes in CKD: The Systolic Blood Pressure Intervention Trial

Many drugs, metabolites, and toxins are cleared by the kidneys via tubular secretion. Whether novel endogenous measures of tubular secretion provide information about kidney, cardiovascular, and mortality risk is uncertain. Longitudinal subgroup analysis of clinical trial participants. 2,089 Systolic Blood Pressure Intervention Trial participants with estimated glomerular filtration rate (eGFR)<60 mL/min/1.73 m2 at baseline. Summary score incorporating urine-to-plasma ratios of 10 endogenous secretion markers measured in paired urine and plasma samples at baseline. The primary outcome was longitudinal change in eGFR. Secondary outcomes included chronic kidney disease (CKD) progression (≥50% eGFR decline or incident kidney failure requiring dialysis or kidney transplantation), a cardiovascular disease (CVD) composite (myocardial infarction, acute coronary syndrome, stroke, acute decompensated heart failure, or death from cardiovascular causes), and mortality. Linear mixed-effect models were used to evaluate the association between the secretion score and change in eGFR, and Cox proportional hazards models were used to evaluate associations with CKD progression, CVD, and mortality. At baseline, mean age was 73 ± 9 years and eGFR was 46 ± 11 mL/min/1.73 m2. During a median follow-up of 3.3 years, mean change in eGFR was-1.44% per year, and 72 CKD progression events, 272 CVD events, and 144 deaths occurred. In multivariable analyses, lower secretion score was associated with faster eGFR decline and greater risk of CKD progression, CVD, and mortality. After further adjustment for baseline eGFR and albuminuria, each 1-standard deviation lower secretion score was associated with faster eGFR decline (-0.65% per year; 95% CI,-0.84% to-0.46%), but not CKD progression (HR, 1.23; 95% CI, 0.96-1.58), CVD (HR, 1.02; 95% CI, 0.89-1.18),or mortality (HR, 0.90; 95% CI, 0.74-1.09). The secretion score association with eGFR decline appeared stronger in participants with baseline eGFR<45 mL/min/1.73 m2 (P for interaction <0.001). Persons with diabetes and proteinuria >1 g/d were excluded. Among SPRINT participants with CKD, lower estimated tubular secretion was associated with faster eGFR decline, independent of baseline eGFR and albuminuria, but not with CKD progression, CVD, or mortality.

Metabolomic Profiling Identifies New Endogenous Markers of Tubular Secretory Clearance.

The proximal tubules eliminate protein-bound toxins and drugs through secretion. Measurements or estimates of GFR do not necessarily reflect the physiologically distinct process of secretion. Clinical assessment of this important intrinsic kidney function requires endogenous markers that are highly specific for secretory transport. We used metabolomics profiling to identify candidate markers of tubular secretory clearance in 50 participants from a kidney pharmacokinetics study. We measured metabolites in three sequential plasma samples and a concurrent 10-hour timed urine sample using hydrophilic interaction liquid chromatography/high-resolution mass spectrometry. We quantified the association between estimated kidney clearance and normalized plasma peak height of each candidate solute to the clearance of administered furosemide, a protein-bound, avidly secreted medication. We identified 528 metabolites present in plasma and urine, excluding pharmaceuticals. We found seven highly (>50%) protein-bound and 49 poorly bound solutes with clearances significantly associated with furosemide clearance and 18 solute clearances favoring an association with furosemide clearance by the 90th percentile compared with GFR. We also found four highly bound and 42 poorly bound plasma levels that were significantly associated with furosemide clearance. We found several candidate metabolites whose kidney clearances or relative plasma levels are highly associated with furosemide clearance, an avidly secreted tracer medication of the organic anion transporters, highlighting their potential as endogenous markers of proximal tubular secretory clearance.

Construct a classification decision tree model to select the optimal equation for estimating glomerular filtration rate and estimate it more accurately

Chronic kidney disease (CKD) has become a worldwide public health problem and accurate assessment of renal function in CKD patients is important for the treatment. Although the glomerular filtration rate (GFR) can accurately evaluate the renal function, the procedure of measurement is complicated. Therefore, endogenous markers are often chosen to estimate GFR indirectly. However, the accuracy of the equations for estimating GFR is not optimistic. To estimate GFR more precisely, we constructed a classification decision tree model to select the most befitting GFR estimation equation for CKD patients. By searching the HIS system of the First Affiliated Hospital of Zhejiang Chinese Medicine University for all CKD patients who visited the hospital from December 1, 2018 to December 1, 2021 and underwent Gate’s method of 99mTc-DTPA renal dynamic imaging to detect GFR, we eventually collected 518 eligible subjects, who were randomly divided into a training set (70%, 362) and a test set (30%, 156). Then, we used the training set data to build a classification decision tree model that would choose the most accurate equation from the four equations of BIS-2, CKD-EPI(CysC), CKD-EPI(Cr-CysC) and Ruijin, and the equation was selected by the model to estimate GFR. Next, we utilized the test set data to verify our tree model, and compared the GFR estimated by the tree model with other 13 equations. Root Mean Square Error (RMSE), Mean Absolute Error (MAE) and Bland–Altman plot were used to evaluate the accuracy of the estimates by different methods. A classification decision tree model, including BSA, BMI, 24-hour Urine protein quantity, diabetic nephropathy, age and RASi, was eventually retrieved. In the test set, the RMSE and MAE of GFR estimated by the classification decision tree model were 12.2 and 8.5 respectively, which were lower than other GFR estimation equations. According to Bland–Altman plot of patients in the test set, the eGFR was calculated based on this model and had the smallest degree of variation. We applied the classification decision tree model to select an appropriate GFR estimation equation for CKD patients, and the final GFR estimation was based on the model selection results, which provided us with greater accuracy in GFR estimation.

Investigating the Metabolic Level of Endogenous and Exogenous Substances on the Intervention of Traditional Chinese Medicine Fuzheng Yiliu Decoction in a Rat Orthotopic Liver Cancer Model.

BackgroundFuzheng Yiliu decoction (FZYLD), a Chinese formula consisting of four herbs, can be clinically used as an adjuvant therapy after surgery or palliative treatment for advanced liver cancer.MethodsThis study identified the endogenous and exogenous metabolites of FZYLD in rat serum to characterize the underlying mechanism of its antitumor activity, as well as relieving cancer-related weakness. An orthotopic transplantation rat model of HepG2 cells was established and administered with FZYLD by gastric perfusion for 14 days. Cardiopulmonary function and tail suspension test were used to evaluate the bodily weakness of hepatocellular carcinoma (HCC) rats. Tumor weight and size were measured to calculate inhibition ratios. Serum of different concentrations of FZYLD was used to culture the 2-[N-(7-nitrobenz-2-oxa-1, 3-diaxol-4-yl) amino]-2-deoxyglucose-labeled HepG2 cells. IC50 value was measured using MTT assay. Endogenous and exogenous metabolites in rat serum were detected using nuclear magnetic resonance or LC-MS/MS spectroscopy.ResultsFZYLD improved cardiopulmonary function, decreased immobility time in tail suspension test, and yielded tumor inhibition ratios of up to 27%. Serum endogenous markers, such as lipoproteins (high- and low-density lipoproteins), glucose, and valine, and lactic acid metabolic disturbance were recovered, to some extent, in HCC rats. Exogenous metabolites, diosgenin, apigenin-7-O-acetyl-β-D-glucoside, calycosin-7-glucoside, calycosin, ganoderic-acid-A, formononetin, and methylnissolin, became detectable in the blood. FZYLD-containing serum substantially inhibited the proliferation of HepG2-cells. IC50 value was found to be 24.31%. Further, we confirmed that FZYLD could revert energy and lipid metabolism disorders and that its constituents could be bioactive components that induce apoptosis in cancer cells.ConclusionThe present study explained the mechanism of the effect of FZYLD on body empty, fatigue, and low immunity in patients with cancer, offering an efficient way for research of natural compounds in traditional Chinese medicine.

Fasting-mimicking diet cycles reduce neuroinflammation to attenuate cognitive decline in Alzheimer's models.

The effects of fasting-mimicking diet (FMD) cycles in reducing many aging and disease risk factors indicate it could affect Alzheimer's disease (AD). Here, we show that FMD cycles reduce cognitive decline and AD pathology in E4FAD and 3xTg AD mouse models, with effects superior to those caused by protein restriction cycles. In 3xTg mice, long-term FMD cycles reduce hippocampal Aβ load and hyperphosphorylated tau, enhance genesis of neural stem cells, decrease microglia number, and reduce expression of neuroinflammatory genes, including superoxide-generating NADPH oxidase (Nox2). 3xTg mice lacking Nox2 or mice treated with the NADPH oxidase inhibitor apocynin also display improved cognition and reduced microglia activation compared with controls. Clinical data indicate that FMD cycles are feasible and generally safe in a small group of AD patients. These results indicate that FMD cycles delay cognitive decline in AD models in part by reducing neuroinflammation and/or superoxide production in the brain.

Role of c-miR-21, c-miR-126, Redox Status, and Inflammatory Conditions as Potential Predictors of Vascular Damage in T2DM Patients.

The development of type 2 diabetes mellitus (T2DM) vascular complications (VCs) is associated with oxidative stress and chronic inflammation and can result in endothelial dysfunctions. Circulating microRNAs play an important role in epigenetic regulation of the etiology of T2DM. We studied 30 healthy volunteers, 26 T2DM patients with no complications, and 26 T2DM patients with VCs, to look for new biomarkers indicating a risk of developing VCs in T2DM patients. Peripheral blood samples were used to determine redox state, by measuring the endogenous antioxidant defense system (superoxide dismutase, SOD; catalase, CAT; glutathione reductase, GRd; glutathione peroxidase, GPx; and glucose-6-phosphate dehydrogenase, G6DP) and markers of oxidative damage (advanced oxidation protein products, AOPP; lipid peroxidation, LPO). Additionally, inflammatory marker levels (IL-1, IL-6, IL-18, and TNF-α), c-miR-21, and c-miR-126 expression were analyzed. T2DM patients showed the highest oxidative damage with increased GSSG/GSH ratios, LPO, and AOPP levels. In both diabetic groups, we found that diminished SOD activity was accompanied by increased CAT and decreased GRd and G6PD activities. Diabetic patients presented with increased relative expression of c-miR-21 and decreased relative expression of c-miR-126. Overall, c-miR-21, SOD, CAT, and IL-6 had high predictive values for diabetes diagnoses. Finally, our data demonstrated that IL-6 exhibited predictive value for VC development in the studied population. Moreover, c-miR-21 and c-miR-126, along with GPx and AOPP levels, should be considered possible markers for VC development in future studies.

Serum Uromodulin and All-Cause Mortality in Peritoneal Dialysis Patients: A Chinese Cohort Study

Serum Uromodulin and All-Cause Mortality in Peritoneal Dialysis Patients: A Chinese Cohort Study

Anti-Aging Effects of R-Phycocyanin from Porphyra haitanensis on HUVEC Cells and Drosophila melanogaster.

Aging has become a global public health challenge. Many studies have revealed that the excessive generation of ROS and oxidative stress could be the major causative factors contributing to aging. In this study, R-phycocyanin (R-PC) was isolated from Porphyra haitanensis, and its anti-aging ability was explored by natural aging Drosophila melanogaster and H2O2-induced HUVEC cells as the aging model. Results showed that R-PC α and β subunits expressed have antioxidant activity and can inhibit the generation of radicals, exhibiting a protective effect against H2O2-induced apoptotic HUVEC cells death. R-PC prevented the H2O2-induced HUVEC cell cycle phase arrest by regulating cell cycle-related protein. Furthermore, R-PC prevented the H2O2-induced HUVEC cell cycle phase arrest by regulating cell-cycle-related protein expression. In vivo study also indicated that R-PC significantly increased the survival time and alleviated the oxidative stress of Drosophila melanogaster. Moreover, R-PC notably decreased levels of ROS in natural aging flies and inhibited lipid peroxidation by enhancing the expressions of the endogenous stress marker genes (SOD1, SOD2, CAT of Drosophila melanogaster). Taken together, a study on the antioxidation extract from Porphyra haitanensis, such as R-PC, may open a new window for the prevention of anti-aging.

Diagnosis of infectious complications in patients with acute pancreatitis

BACKGROUND: Up to 30% of patients with acute pancreatitis suffer from the severe form of the disease, of which 30% of cases are lethal, significantly rising to 80% at the development of infectious complications.&#x0D; AIM: To improve treatment results of patients with acute pancreatitis due to early diagnostics of infectious complications.&#x0D; MATERIALS AND METHODS: Expression of CD64 antigen on neutrophil membrane (DC64 index of neutrophils) was studied using a flow cytometer Cytomics FC500 (Beckman Coulter, USA) using 3-color combination of direct monoclonal antibodies Beckman Coulter: СD14FITC/CD64PE/CD45PC5. Material was whole blood.&#x0D; RESULTS: A direct correlation of moderate strength with the development of sepsis was found for both the procalcitonin value and C-reactive protein concentration at this period of illness. However, no relations of endogenous intoxication markers with the development of infectious complications were found (correlation coefficients less than 0.4). Thus, it should be noted that the difference in the indices of the studied parameters of the CD64 antigen expression in the groups began to increase exactly during the 23rd week of the disease.&#x0D; CONCLUSION: Based on the literature data, we formulated a working hypothesis, which states that the degree of CD64 receptor expression on peripheral blood neutrophils is an early marker of infectious complications of acute pancreatitis. The value of average fluorescence intensity index of molecules CD64 equal to 10 conventional units was accepted as a threshold value with regard to the development of IE, and the value of 15 conventional unitsas a threshold value with regard to sepsis. The study was conducted in a prospective group of 28 patients. In accordance with the provision of the working hypothesis, the patients were divided into 3 groups depending on the level of average fluorescence intensity index of molecules CD64. Expression of the CD64 receptor on peripheral blood granulocytes as an early laboratory marker of infectious complications of the disease was studied for the first time. We determined sensitivity and specificity, optimal terms of the given research, detected regularities of CD64 expression changes in the course of acute pancreatitis, correlations with other clinical and laboratory indexes, including prospective markers of infection (procalcitonin, C-reactive protein), with the integral scales of severity estimation of patients with acute destructive pancreatitis. Determination of the level of the receptor CD64 expression on the peripheral blood neutrophils showed that this marker reflects the dynamics of the disease course and gives the possibility of the early diagnostics of the infectious complications of acute pancreatitis. The use of this method provides additional information about the development of the surgical infection. It is important that the changes of CD64 antigen expression in dynamics outrun other markers of systemic inflammatory response and sepsis. CD64 antigen expression data on peripheral blood neutrophils is an additional factor in determining differentiated surgical tactics in phase I of the diseases development with regard to acute fluid collections in patients with acute pancreatitis.

Cystatin C and lipocalin — endogenous markers of glomerular filtration in children born prematurely

The need to search for new markers of the functional state of the kidneys is increasing due to the gain in the number of extremely premature infants. The review analyzes publications on the possibilities of assessing kidney function using cystatin C and lipocalin in children born prematurely. The constant rate of cystatin C production in all tissues, its elimination through the renal glomerular filter, the absence of secretion in the proximal tubules, as well as independence from many factors, including gender, age, diet, inflammation are ideal conditions for its use as an endogenous biochemical marker of glomerular filtration. Due to biochemical features, the analysis of serum levels of cystatin C was established to be a promising method in the diagnosis of acute renal injury (AKI) in premature infants. For a comprehensive assessment of kidney function in premature infants, simultaneous determination of lipocalin and cystatin C levels in the blood may be important. At the same time, the evaluation of these indicators may have diagnostic significance in predicting the development of chronic kidney disease in children who underwent AKI in infancy. The absence of reference values of lipocalin and cystatin C in premature infants was concluded to hinder the clinical use of their quantitative analysis for a comprehensive assessment of the functional state of the kidneys.

Novel Sterically Crowded and Conformationally Constrained α-Aminophosphonates with a Near-Neutral pKa as Highly Accurate 31P NMR pH Probes. Application to Subtle pH Gradients Determination in Dictyostelium discoideum Cells.

In order to discover new 31P NMR markers for probing subtle pH changes (<0.2 pH unit) in biological environments, fifteen new conformationally constrained or sterically hindered α-aminophosphonates derived from diethyl(2-methylpyrrolidin-2-yl)phosphonate were synthesized and tested for their pH reporting and cytotoxic properties in vitro. All compounds showed near-neutral pKas (ranging 6.28–6.97), chemical shifts not overlapping those of phosphorus metabolites, and spectroscopic sensitivities (i.e., chemical shifts variation Δδab between the acidic and basic forms) ranging from 9.2–10.7 ppm, being fourfold larger than conventional endogenous markers such as inorganic phosphate. X-ray crystallographic studies combined with predictive empirical relationships and ab initio calculations addressed the inductive and stereochemical effects of substituents linked to the protonated amine function. Satisfactory correlations were established between pKas and both the 2D structure and pyramidalization at phosphorus, showing that steric crowding around the phosphorus is crucial for modulating Δδab. Finally, the hit 31P NMR pH probe 1b bearing an unsubstituted 1,3,2-dioxaphosphorinane ring, which is moderately lipophilic, nontoxic on A549 and NHLF cells, and showing pKa = 6.45 with Δδab = 10.64 ppm, allowed the first clear-cut evidence of trans-sarcolemmal pH gradients in normoxic Dictyostelium discoideum cells with an accuracy of <0.05 pH units.

Modeling infection from SARS-CoV-2 wastewater concentrations: promise, limitations, and future directions.

Estimating total infection levels, including unreported and asymptomatic infections, is important for understanding community disease transmission. Wastewater can provide a pooled community sample to estimate total infections that is independent of case reporting biases toward individuals with moderate to severe symptoms and by test-seeking behavior and access. We derive three mechanistic models for estimating community infection levels from wastewater measurements based on a description of the processes that generate SARS-CoV-2 RNA signals in wastewater and accounting for the fecal strength of wastewater through endogenous microbial markers, daily flow, and per-capita wastewater generation estimates. The models are illustrated through two case studies of wastewater data collected during 2020-2021 in Virginia Beach, VA, and Santa Clara County, CA. Median simulated infection levels generally were higher than reported cases, but at times, were lower, suggesting a discrepancy between the reported cases and wastewater data, or inaccurate modeling results. Daily simulated infection estimates showed large ranges, in part due to dependence on highly variable clinical viral fecal shedding data. Overall, the wastewater-based mechanistic models are useful for normalization of wastewater measurements and for understanding wastewater-based surveillance data for public health decision-making but are currently limited by lack of robust SARS-CoV-2 fecal shedding data.

Individual dynamic prediction of clinical endpoint from large dimensional longitudinal biomarker history: a landmark approach

BackgroundThe individual data collected throughout patient follow-up constitute crucial information for assessing the risk of a clinical event, and eventually for adapting a therapeutic strategy. Joint models and landmark models have been proposed to compute individual dynamic predictions from repeated measures to one or two markers. However, they hardly extend to the case where the patient history includes much more repeated markers. Our objective was thus to propose a solution for the dynamic prediction of a health event that may exploit repeated measures of a possibly large number of markers.MethodsWe combined a landmark approach extended to endogenous markers history with machine learning methods adapted to survival data. Each marker trajectory is modeled using the information collected up to the landmark time, and summary variables that best capture the individual trajectories are derived. These summaries and additional covariates are then included in different prediction methods adapted to survival data, namely regularized regressions and random survival forests, to predict the event from the landmark time. We also show how predictive tools can be combined into a superlearner. The performances are evaluated by cross-validation using estimators of Brier Score and the area under the Receiver Operating Characteristic curve adapted to censored data.ResultsWe demonstrate in a simulation study the benefits of machine learning survival methods over standard survival models, especially in the case of numerous and/or nonlinear relationships between the predictors and the event. We then applied the methodology in two prediction contexts: a clinical context with the prediction of death in primary biliary cholangitis, and a public health context with age-specific prediction of death in the general elderly population.ConclusionsOur methodology, implemented in R, enables the prediction of an event using the entire longitudinal patient history, even when the number of repeated markers is large. Although introduced with mixed models for the repeated markers and methods for a single right censored time-to-event, the technique can be used with any other appropriate modeling technique for the markers and can be easily extended to competing risks setting.

A comparison of four established GFR formulas to estimate measured GFR and changes in GFR in adult kidney transplant recipients

The accurate assessment of glomerular filtration rate (GFR) is important in the follow-up of kidney transplant recipients in order to identify graft dysfunction. A number of formulas have been proposed to calculate GFR from endogenous plasma markers such as creatinine or cystatin C since measuring GFR using exogenous markers is troublesome. This study compares and evaluates the ability of four different GFR formulas to estimate kidney graft function and to detect changes in GFR in kidney transplant recipients. The study included patients from the prospective, multicenter CONTEXT trial in kidney transplant recipients. GFR was measured using plasma clearance of 51Cr-EDTA and estimated using the MDRD, CKD-EPI Creatinine, CKD-EPI Cystatin C and CKD-EPI Cystatin C + Creatinine equations at three (n = 83) and twelve (n = 65) months post-transplantation. For each formula mean bias, precision, and accuracy were evaluated. The MDRD equation had the lowest mean bias (0.2 ml/min/1.73 m2), whereas the CKD-EPI Cystatin C + Creatinine equation had the highest precision (8 ml/min/1.73 m2). Accuracy at three months were similar for all equations (P30 > 80%) except for the CKD-EPI Cystatin C equation, which performed poorer (P30 = 55%). None of the formulas evaluated avoided misclassification of changes in GFR. The most optimal combination of precision and accuracy suggests the use of CKD-EPI Creatinine + Cystatin C equation in kidney transplant recipients.