Evaluation of testosterone, estradiol and progesterone immunoassay calibrators by liquid chromatography mass spectrometry.

OBJECTIVES: In clinical practice, steroid measurements are performed mainly by direct, non-extraction immunoassays adapted to high throughput, automated immunoassay platforms and employing secondary calibrators. The accuracy of such steroid immunoassays is limited by cross-reactivity with structurally related steroids and nonspecific matrix interference as well as the metrological traceability of manufacturer supplied calibrators. The accuracy of steroid immunoassay calibrators has been little investigated by independent chemical methods. METHODS: Steroid concentrations of 41 calibrators (4-6 replicates per calibrator) supplied by four manufacturers for use in testosterone (T), estradiol (E2), and progesterone (P4) commercial immunoassays were measured by ultra-pressure liquid chromatography-mass spectrometry (UPLC-MS). RESULTS: Among 14 non-zero T calibrators, six (43 %) deviated significantly from the label concentration with 29 % outside 20 % of it. Among 14 E2 calibrators, eight (57 %) deviated significantly, whereas seven (50 %) were outside 20 % of the label concentration. Among 11 P4 calibrators, eight (73 %) deviated significantly whereas four (36 %) were outside within 20 % of the label concentration. CONCLUSIONS: We conclude that inaccurate calibration of manufacturer's supplied standards may contribute to inaccuracy of commercial direct steroid immunoassays.

Sex Hormones and Adrenal Steroids: Biological Variation Estimated Using Direct and Indirect Methods.

BACKGROUND: Biological variation (BV) data may be used to develop analytical performance specifications (APS), reference change values (RCV), and support the applicability of population reference intervals. This study estimates within-subject BV (CVI) for several endocrine biomarkers using 3 different methodological approaches. METHODS: For the direct method, 30 healthy volunteers were sampled weekly for 10 consecutive weeks. Samples were analyzed in duplicate for 17-hydroxyprogesterone (17-OHP), androstenedione, cortisol, cortisone, estradiol, follicle-stimulating hormone (FSH), luteinizing hormone (LH), sex hormone-binding globulin (SHBG), and testosterone. A CV-ANOVA with outlier removal and a Bayesian model were applied to derive the CVI. For estradiol, FSH and LH, only the male subgroup was included. In the indirect method, using the same analytes and groups, pairs of sequential results were extracted from the laboratory information system. The total result variation for individual pairs was determined by identifying a central gaussian distribution in the ratios of the result pairs. The CVI was then estimated by removing the effect of analytical variation. RESULTS: The estimated CVI from the Bayesian model (µCVP(i)) in the total cohort was: 17-OHP, 23%; androstenedione, 20%; cortisol, 18%; cortisone, 11%; SHBG, 7.4%; testosterone, 16%; and for the sex hormones in men: estradiol, 14%; FSH, 8%; and LH, 26%. CVI-heterogeneity was present for most endocrine markers. Similar CVI data were estimated using the CV-ANOVA and the indirect method. CONCLUSIONS: Similar CVI data were obtained using 2 different direct and one indirect method. The indirect approach is a low-cost alternative ensuring implementation of CVI data applicable for local conditions.

LC-MS/MS method for simultaneous quantification of ten antibiotics in human plasma for routine therapeutic drug monitoring.

Background: Optimizing antimicrobial therapy to attain drug exposure that limits the emergence of resistance, effectively treats the infection, and reduces the risk of side effects is of a particular importance in critically ill patients, in whom normal functions are augmented or/and are infected with pathogens less sensitive to treatment. Achievement of these goals can be enhanced by therapeutic drug monitoring (TDM) for many antibiotics. A liquid chromatography tandem mass spectrometry (LC-MS/MS) method is presented here for simultaneous quantification of ten antimicrobials: cefazolin (CZO), cefepime (CEP), cefotaxime (CTA), ceftazidime (CTZ), ciprofloxacin (CIP), flucloxacillin (FLU), linezolid (LIN), meropenem (MER), piperacillin (PIP) and tazobactam (TAZ) in human plasma. Methods: Plasma samples were precipitated with acetonitrile and injected into the LC-MS/MS. Chromatographic separation was on a Waters Acquity BEH C18 column. Compounds were eluted with water and acetonitrile containing 0.1 % formic acid, using a gradient (0.5-65 % B), in 3.8 min. The flow rate was 0.4 mL/min, and the run time was 5.8 min. Results: The calibration curves were linear across the tested concentration ranges (0.5-250, CZO, CEP, CTA, CTZ and FLU; 0.2-100, MER and TAZ; 0.1-50, CIP and LIN and 1-500 mg/L, PIP). The intra and inter-day imprecision was < 11 %. Accuracy ranged from 95 to 114 %. CTZ and MER showed ionization suppression while CIP showed ionization enhancement, which was normalized with the use of the internal standard. Conclusion: An LC-MS/MS method for simultaneous quantification of ten antimicrobials in human plasma was developed for routine TDM.

Targeting RTN4/NoGo-Receptor reduces levels of ALS protein ataxin-2.

Gene-based therapeutic strategies to lower ataxin-2 levels are emerging for the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and spinocerebellar ataxia type 2 (SCA2). Additional strategies to lower levels of ataxin-2 could be beneficial. Here, we perform a genome-wide arrayed small interfering RNA (siRNA) screen in human cells and identify RTN4R, the gene encoding the RTN4/NoGo-Receptor, as a potent modifier of ataxin-2 levels. RTN4R knockdown, or treatment with a peptide inhibitor, is sufficient to lower ataxin-2 protein levels in mouse and human neurons in vitro, and Rtn4r knockout mice have reduced ataxin-2 levels in vivo. We provide evidence that ataxin-2 shares a role with the RTN4/NoGo-Receptor in limiting axonal regeneration. Reduction of either protein increases axonal regrowth following axotomy. These data define the RTN4/NoGo-Receptor as a novel therapeutic target for ALS and SCA2 and implicate the targeting of ataxin-2 as a potential treatment following nerve injury.

Hypertension alters the function and expression profile of the peptide cotransporters PEPT1 and PEPT2 in the rodent renal proximal tubule.

Hypertension is a major risk factor for kidney and cardiovascular disease. The treatment of hypertensive individuals by selected ACE inhibitors and certain di-and tripeptides halts the progression of renal deterioration and extends life-span. Renal reabsorption of these low molecular weight substrates are mediated by the PEPT1 and PEPT2 cotransporters. This study aims to investigate whether hypertension and ageing affects renal PEPT cotransporters at gene, protein expression and distribution as well as function in the superficial cortex and the outer medulla of the kidney. Membrane vesicles from the brush border (BBMV) and outer medulla (OMMV) were isolated from the kidneys of young Wistar Kyoto (Y-WKY), young spontaneously hypertensive (Y-SHR), and middle aged SHR (M-SHR) rats. Transport activity was measured using the substrate, ß-Ala-Lys (AMCA). Gene expression levels of PEPT genes were assessed with qRT-PCR while renal localisation of PEPT cotransporters was examined by immunohistochemistry with Western Blot validation. The Km and Vmax of renal PEPT1 were decreased significantly in SHR compared to WKY BBMV, whilst the Vmax of PEPT2 showed differences between SHR and WKY. By contrast to the reported cortical distribution of PEPT1, PEPT1-staining was detected in the outer medulla, whilst PEPT2 was expressed primarily in the cortex of all SHR; PEPT1 was significantly upregulated in the cortex of Y-SHR. These outcomes are indicative of a redistribution of PEPT1 and PEPT2 in the kidney proximal tubule under hypertensive conditions that has potential repercussions for nutrient handling and the therapeutic use of ACE inhibitors in hypertensive individuals.

Post translational modifications of Trifolitoxin: a blue fluorescent peptide antibiotic.

Trifolitoxin (TFX, C41H63N15O15S) is a selective, ribosomally-synthesized, post-translationally modified, peptide antibiotic, produced by Rhizobium leguminosarum bv. trifolii T24. TFX specifically inhibits α-proteobacteria, including the plant symbiont Rhizobium spp., the plant pathogen Agrobacterium spp. and the animal pathogen Brucella abortus. TFX-producing strains prevent legume root nodulation by TFX-sensitive rhizobia. TFX has been isolated as a pair of geometric isomers, TFX1 and TFX2, which are derived from the biologically inactive primary amino acid sequence: Asp-Ile-Gly-Gly-Ser-Arg-Gln-Gly-Cys-Val-Ala. Gly-Cys is present as a thiazoline ring and the Arg-Gln-Gly sequence is extensively modified to a UV absorbing, blue fluorescent chromophore. The chromophore consists of a conjugated, 5-membered heterocyclic ring and side chain of modified glutamine.

Discovery of Spiro-azaindoline Inhibitors of Hematopoietic Progenitor Kinase 1 (HPK1).

Hematopoietic progenitor kinase 1 (HPK1) is implicated as a negative regulator of T-cell receptor-induced T-cell activation. Studies using HPK1 kinase-dead knock-in animals have demonstrated the loss of HPK1 kinase activity resulted in an increase in T-cell function and tumor growth inhibition in glioma models. Herein, we describe the discovery of a series of small molecule inhibitors of HPK1. Using a structure-based drug design approach, the kinase selectivity of the molecules was significantly improved by inducing and stabilizing an unusual P-loop folded binding mode. The metabolic liabilities of the initial 7-azaindole high-throughput screening hit were mitigated by addressing a key metabolic soft spot along with physicochemical property-based optimization. The resulting spiro-azaindoline HPK1 inhibitors demonstrated improved in vitro ADME properties and the ability to induce cytokine production in primary human T-cells.

Agrocinopine C, a Ti-plasmid-coded enzyme-product, is a 2-O, 6-O linked phosphodiester of D-Glucose and sucrose.

Agrocinopine C is a small molecule found in crown gall tumours induced by pathogenic Agrobacterium radiobacter carrying the tumour-inducing plasmid pTi Bo542. This phosphodiester opine was isolated (at 0.02 g/100 g fresh wt.) from sunflower (Helianthus annuus L.) galls. It is structurally related to agrocinopine A and is a glucose-2-phosphodiester linked to the C6-hydroxy-methyl group of the glucose moiety of sucrose. Sugar-2-phosphates are uncommon in plant tissues, whether transformed by Agrobacterium or not. 1H and 31P NMR signal multiplicity indicates five-fold anomeric complexity of agrocinopine C in solution, implying that the permeases taking up these sucrose-phosphodiesters could recognise any one of the five anomers. Data suggests that the open chain aldehyde forms of the 2-phosphorylated opines agrocinopine C and agrocinopine A and the corresponding phosphorylated glucose-2-phosphoramidate component of the antibiotic agrocin 84 play a central role in agrocin's selective toxicity to certain strains of Agrobacterium after uptake via Ti plasmid-encoded permeases.

AACC Guidance Document on Laboratory Investigation of Acute Kidney Injury.

BACKGROUND: Acute kidney injury (AKI) is a sudden episode of kidney damage or failure affecting up to 15% of hospitalized patients and is associated with serious short- and long-term complications, mortality, and health care costs. Current practices to diagnose and stage AKI are variable and do not factor in our improved understanding of the biological and analytical variability of creatinine. In addition, the emergence of biomarkers, for example, cystatin C, insulin-like growth factor binding protein 7, and tissue inhibitor of metalloproteinases 2, and electronic notification tools for earlier detection of AKI, highlights the need for updated recommendations to address these developments. CONTENT: This AACC Academy guidance document is intended to provide laboratorians and clinicians up-to-date information regarding current best practices for the laboratory investigation of AKI. Topics covered include: clinical indications for further investigating potential AKI, analytical considerations for creatinine assays, the impact of biological variability on diagnostic thresholds, defining "baseline" creatinine, role of traditional markers (urine sodium, fractional excretion of sodium, fractional excretion of urea, and blood urea-to-creatinine ratio), urinary microscopic examination, new biomarkers, improving AKI-associated test utilization, and the utility of automated AKI alerts. SUMMARY: The previous decade brought us a significant number of new studies characterizing the performance of existing and new biomarkers, as well as potential new tools for early detection and notification of AKI. This guidance document is intended to inform clinicians and laboratorians on the best practices for the laboratory investigation of AKI, based on expert recommendations where the preponderance of evidence is available.

Effects of Allopurinol on the Progression of Chronic Kidney Disease.

BACKGROUND: Elevated serum urate levels are associated with progression of chronic kidney disease. Whether urate-lowering treatment with allopurinol can attenuate the decline of the estimated glomerular filtration rate (eGFR) in patients with chronic kidney disease who are at risk for progression is not known. METHODS: In this randomized, controlled trial, we randomly assigned adults with stage 3 or 4 chronic kidney disease and no history of gout who had a urinary albumin:creatinine ratio of 265 or higher (with albumin measured in milligrams and creatinine in grams) or an eGFR decrease of at least 3.0 ml per minute per 1.73 m2 of body-surface area in the preceding year to receive allopurinol (100 to 300 mg daily) or placebo. The primary outcome was the change in eGFR from randomization to week 104, calculated with the Chronic Kidney Disease Epidemiology Collaboration creatinine equation. RESULTS: Enrollment was stopped because of slow recruitment after 369 of 620 intended patients were randomly assigned to receive allopurinol (185 patients) or placebo (184 patients). Three patients per group withdrew immediately after randomization. The remaining 363 patients (mean eGFR, 31.7 ml per minute per 1.73 m2; median urine albumin:creatinine ratio, 716.9; mean serum urate level, 8.2 mg per deciliter) were included in the assessment of the primary outcome. The change in eGFR did not differ significantly between the allopurinol group and the placebo group (-3.33 ml per minute per 1.73 m2 per year [95% confidence interval {CI}, -4.11 to -2.55] and -3.23 ml per minute per 1.73 m2 per year [95% CI, -3.98 to -2.47], respectively; mean difference, -0.10 ml per minute per 1.73 m2 per year [95% CI, -1.18 to 0.97]; P = 0.85). Serious adverse events were reported in 84 of 182 patients (46%) in the allopurinol group and in 79 of 181 patients (44%) in the placebo group. CONCLUSIONS: In patients with chronic kidney disease and a high risk of progression, urate-lowering treatment with allopurinol did not slow the decline in eGFR as compared with placebo. (Funded by the National Health and Medical Research Council of Australia and the Health Research Council of New Zealand; CKD-FIX Australian New Zealand Clinical Trials Registry number, ACTRN12611000791932.).

Tumour lysis syndrome in a patient with undifferentiated endometrial stromal sarcoma.

•Tumour lysis syndrome is an oncologic emergency.•Tumour lysis syndrome is most commonly encountered in hematologic malignancies.•Herein we report a case of tumour lysis syndrome in an endometrial stromal sarcoma.

An evaluation of risk factors to predict target concentration non-attainment in critically ill patients prior to empiric ß-lactam therapy.

To determine whether target concentration non-attainment can be anticipated in critically ill patients prior to initiating empiric ß-lactam antibiotic therapy based on readily available clinical factors. Retrospective review of consecutive patients treated with piperacillin or meropenem and who underwent therapeutic drug monitoring (TDM) at St Vincent's Hospital (Sydney, Australia) between January 2013 and December 2015 was performed. Predefined subgroups were patients who received continuous renal replacement therapy (CRRT) and those who did not (non-CRRT). Potential risk factors were evaluated by correlation with ß-lactam antibiotic trough concentrations (Cmin) lower than or equal to targeted minimum inhibitory concentration (MIC). Only the first drug concentration after initiation of the antibiotic treatment was included to reflect empirical dose selection. A total of n = 249 patients (piperacillin, n = 169; meropenem, n = 80) were investigated. For non-CRRT patients (n = 210), multivariate analysis demonstrated the following: male gender (p = 0.006); younger age (p = 0.015); prescribed daily antibiotic dose less than 1.5 times the product information recommendations (p = 0.004); lack of positive microbiology (p = 0.006); lower overall illness severity (p = 0.005); and estimated glomerular filtration rate (eGFR) ≥ 90 mL/min/1.73 m2 (p < 0.001), to be associated with Cmin ≤ MIC. No predictor variable was found to be significantly associated with Cmin ≤ MIC for the CRRT cohort. Evaluating the risk of target concentration non-attainment using simple clinical factors is possible at the bedside for non-CRRT patients prior to empiric antibiotic initiation. Clinicians should be wary of selecting doses based on the product information especially when treating younger male patients with apparently 'normal' renal function.

A2A Adenosine Receptor Gene Deletion or Synthetic A2A Antagonist Liberate Tumor-Reactive CD8+ T Cells from Tumor-Induced Immunosuppression.

Tumor hypoxia-driven accumulation of extracellular adenosine was shown to facilitate tumor evasion by engaging the immunosuppressive, intracellular cAMP-elevating A2 adenosine receptors (A2R) on tumor-reactive effector T cells, but there remains a need for careful evaluation of the limiting factors and properties of A2R blockade-enabled antitumor immunity. In studies of A2AR and/or A2BR gene-deficient mice, we found that A2AR deletion-but not A2BR deletion-liberates endogenous CD8+ T cell antitumor immunity against weakly immunogenic MCA205 sarcomas. Studies of adoptively transferred A2AR-/-, A2BR-/-, or A2AR-/-/A2BR-/- tumor-reactive T cells confirmed that immunosuppression in the tumor microenvironment was mediated by A2AR on CD8+ T cells. Treatment with A2AR antagonist mimicked A2AR gene deletion in adoptive T cell immunotherapy. This therapeutic benefit of targeting A2AR was independent of the anatomical location of tumor growth. The enhanced antitumor reactivity also led to the eradication of established intracranial tumors, which was associated with mouse survival and the maintenance of long-lasting, tumor-specific immunological memory. The blockade of the A2AR on adoptively transferred T cells by synthetic A2AR antagonist led to higher levels of IFN-γ secretion by tumor-infiltrating CD8+ T cells. These data clarify the mechanism of hypoxia-driven immunosuppression in the tumor microenvironment by A2AR on tumor-reactive CD8+ T cells and show that selective A2AR antagonists can be effective in improving the outcomes of T cell-based immunotherapies. Demonstration of the T cell dose dependency of tumor rejection points to a major limitation of current cancer immunotherapies, in which the presence of sufficient numbers of tumor-reactive T cells in a patient is not known.

Estimated Glomerular Filtration Rate; Laboratory Implementation and Current Global Status.

In 2002, the Kidney Disease Outcomes Quality Initiative guidelines for identifying and treating CKD recommended that clinical laboratories report estimated glomerular filtration rate (eGFR) with every creatinine result to assist clinical practitioners to identify people with early-stage CKD. At that time, the original Modification of Diet in Renal Disease (MDRD) Study equation based on serum creatinine measurements was recommended for calculating eGFR. Because the MDRD Study equation was developed using a nonstandardized creatinine method, a Laboratory Working Group of the National Kidney Disease Education program was formed and implemented standardized calibration traceability for all creatinine methods from global manufacturers by approximately 2010. A modified MDRD Study equation for use with standardized creatinine was developed. The Chronic Kidney Disease Epidemiology Collaboration developed a new equation in 2009 that was more accurate than the MDRD Study equation at values above 60 mL/min/1.73 m2. As of 2017, reporting eGFR with creatinine is almost universal in many countries. A reference system for cystatin C became available in 2010, and manufacturers are in the process to standardize cystatin C assays. Equations for eGFR based on standardized cystatin C alone and with creatinine are now available from the Chronic Kidney Disease Epidemiology Collaboration and other groups.

High Baseline Levels of Tumor Necrosis Factor Receptor 1 Are Associated With Progression of Kidney Disease in Indigenous Australians With Diabetes: The eGFR Follow-up Study.

OBJECTIVE: To examine the association between soluble tumor necrosis factor receptor 1 (sTNFR1) levels and kidney disease progression in Indigenous Australians at high risk of kidney disease. RESEARCH DESIGN AND METHODS: This longitudinal observational study examined participants aged ≥18 years recruited from >20 sites across diabetes and/or kidney function strata. Baseline measures included sTNFR1, serum creatinine, urine albumin-to-creatinine ratio (uACR), HbA1c, C-reactive protein (CRP), waist-to-hip ratio, systolic blood pressure, and medical history. Linear regression was used to estimate annual change in estimated glomerular filtration rate (eGFR) for increasing sTNFR1, and Cox proportional hazards were used to estimate the hazard ratio (HR) and 95% CI for developing a combined renal outcome (first of a ≥30% decline in eGFR with a follow-up eGFR <60 mL/min/1.73 m2, progression to renal replacement therapy, or renal death) for increasing sTNFR1. RESULTS: Over a median of 3 years, participants with diabetes (n = 194) in the highest compared with the lowest quartile of sTNFR1 experienced significantly greater eGFR decline (-4.22 mL/min/1.73 m2/year [95% CI -7.06 to -1.38]; P = 0.004), independent of baseline age, sex, eGFR, and uACR. The adjusted HR (95% CI) for participants with diabetes per doubling of sTNFR1 for the combined renal outcome (n = 32) was 3.8 (1.1-12.8; P = 0.03). No association between sTNFR1 and either renal outcome was observed for those without diabetes (n = 259). CONCLUSIONS: sTNFR1 is associated with greater kidney disease progression independent of albuminuria and eGFR in Indigenous Australians with diabetes. Further research is required to assess whether TNFR1 operates independently of other metabolic factors associated with kidney disease progression.

Geissoschizine synthase controls flux in the formation of monoterpenoid indole alkaloids in a Catharanthus roseus mutant.

MAIN CONCLUSION: A Catharanthus roseus mutant accumulates high levels of ajmalicine at the expense of catharanthine and vindoline. The altered chemistry depends on increased expression and biochemical activities of strictosidine ß-glucosidase and ajmalicine synthase activities and reduced expression and biochemical activity of geissoschizine synthase. The Madagascar periwinkle [Catharanthus roseus (L.) G. Don] is a commercially important horticultural flower species and is a valuable source for several monoterpenoid indole alkaloids (MIAs), such as the powerful antihypertensive drug ajmalicine and the antineoplastic agents, vinblastine and vincristine. While biosynthesis of the common MIA precursor strictosidine and its reactive aglycones has been elucidated, the branch point steps leading to the formation of different classes of MIAs remain poorly characterized. Screening of 3600 ethyl methyl sulfonate mutagenized C. roseus plants using a simple thin-layer chromatography screen yielded a mutant (M2-0754) accumulating high levels of ajmalicine together with significantly lower levels of catharanthine and vindoline. Comparative bioinformatic analyses, virus-induced gene silencing, and biochemical characterization identified geissoschizine synthase, the gateway enzyme that controls flux for the formation of iboga and aspidosperma MIAs. The reduction of geissoschizine synthase transcripts in this high ajmalicine mutant, together with increased transcripts and enzyme activities of strictosidine ß-glucosidase and of heteroyohimbine synthase, explains the preferential formation of ajmalicine in the mutant instead of catharanthine and vindoline that accumulates in the wild-type parent. Reciprocal crosses established that that the high ajmalicine phenotype is inherited as a Mendelian recessive trait.