Trans-ethnic genome-wide association study of blood metabolites in the Chronic Renal Insufficiency Cohort (CRIC) study.

Metabolomics genome wide association study (GWAS) help outline the genetic contribution to human metabolism. However, studies to date have focused on relatively healthy, population-based samples of White individuals. Here, we conducted a GWAS of 537 blood metabolites measured in the Chronic Renal Insufficiency Cohort (CRIC) Study, with separate analyses in 822 White and 687 Black study participants. Trans-ethnic meta-analysis was then applied to improve fine-mapping of potential causal variants. Mean estimated glomerular filtration rate was 44.4 and 41.5 mL/min/1.73m2 in the White and Black participants, respectively. There were 45 significant metabolite associations at 19 loci, including novel associations at PYROXD2, PHYHD1, FADS1-3, ACOT2, MYRF, FAAH, and LIPC. The strength of associations was unchanged in models additionally adjusted for estimated glomerular filtration rate and proteinuria, consistent with a direct biochemical effect of gene products on associated metabolites. At several loci, trans-ethnic meta-analysis, which leverages differences in linkage disequilibrium across populations, reduced the number and/or genomic interval spanned by potentially causal single nucleotide polymorphisms compared to fine-mapping in the White participant cohort alone. Across all validated associations, we found strong concordance in effect sizes of the potentially causal single nucleotide polymorphisms between White and Black study participants. Thus, our study identifies novel genetic determinants of blood metabolites in chronic kidney disease, demonstrates the value of diverse cohorts to improve causal inference in metabolomics GWAS, and underscores the shared genetic basis of metabolism across race.

Ct Values Do Not Predict Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Transmissibility in College Students.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly contagious and has caused significant medical/socioeconomic impacts. Other than vaccination, effective public health measures, including contact tracing, isolation, and quarantine, is critical for deterring viral transmission, preventing infection progression and resuming normal activities. Viral transmission is affected by many factors, but the viral load and vitality could be among the most important ones. Although in vitro studies have indicated that the amount of virus isolated from infected individuals affects the successful rate of virus isolation, whether the viral load carried at the individual level would determine the transmissibility was unknown. We examined whether the cycle threshold (Ct) value, a measurement of viral load by RT-PCR assay, could differentiate the spreaders from the non-spreaders in a population of college students. Our results indicate that while at the population level the Ct value is lower, suggesting a higher viral load, in the symptomatic spreaders than that in the asymptomatic non-spreaders, there is a significant overlap in the Ct values between the two groups. Thus, Ct value, or the viral load, at the individual level could not predict the transmissibility. Instead, a sensitive method to detect the presence of virus is needed to identify asymptomatic individuals who may carry a low viral load but can still be infectious.

Anemia and Incident End-Stage Kidney Disease.

BACKGROUND: Chronic kidney disease (CKD) progression can be a cause and potentially a consequence of anemia. Previous studies suggesting that anemia is associated with CKD progression have not utilized methodologic approaches to address time-dependent confounding. METHODS: We evaluated the association of anemia (defined using World Health Organization criteria of hemoglobin <12 g/dL in women and <13 g/dL in men) with incident ESRD and all-cause death in individuals with CKD using data from the Chronic Renal Insufficiency Cohort Study. Marginal structural models were used to account for time-dependent confounding. RESULTS: Among 3919 participants, 1859 (47.4%) had anemia at baseline. Over median follow up of 7.8 years, we observed 1,010 ESRD events and 994 deaths. In multivariable analyses, individuals with anemia had higher risk for ESRD compared to those without (HR 1.62, 95% CI 1.24-2.11). In stratified analyses, the increased risk for incident ESRD with anemia was observed in males (HR 2.15, 95% CI: 1.53-3.02) but not females (HR 1.20, 95% CI 0.82-1.78. The association between anemia and ESRD was significant among all racial/ethnic groups except non-Hispanic blacks (non-Hispanic white, HR 2.16, 95% CI 1.53-3.06; Hispanic, HR 1.92, 1.04-3.51; others, HR 2.94; 95% CI 1.16-7.44; non-Hispanic black, HR 1.39; 95% CI 0.95-2.02). There was no association between anemia and all-cause death. CONCLUSIONS: In this cohort, anemia was independently associated with increased risk for incident ESRD. Future work is needed to evaluate the mechanisms by which anemia leads to CKD progression as well as the impact of novel therapeutic agents to treat anemia.

Elevated lipoxygenase and cytochrome P450 products predict progression of chronic kidney disease.

BACKGROUND: The clinical relevance of arachidonic acid (AA) metabolites in chronic kidney disease (CKD) progression is poorly understood. We aimed to compare the concentrations of 85 enzymatic pathway products of AA metabolism in patients with CKD who progressed to end-stage kidney disease (ESKD) versus patients who did not in a subcohort of Chronic Renal Insufficiency Cohort (CRIC) and to estimate the risk of CKD progression and major cardiovascular events by levels of AA metabolites and their link to enzymatic metabolic pathways. METHODS: A total 123 patients in the CRIC study who progressed to ESKD were frequency matched with 177 nonprogressors and serum eicosanoids were quantified by mass spectrometry. We applied serum collected at patients' Year 1 visit and outcome of progression to ESKD was ascertained over the next 10 years. We used logistic regression models for risk estimation. RESULTS: Baseline 15-hydroxyeicosatetraenoate (HETE) and 20-HETE levels were significantly elevated in progressors (false discovery rate Q ≤ 0.026). The median 20-HETE level was 7.6 pmol/mL [interquartile range (IQR) 4.2-14.5] in progressors and 5.4 pmol/mL (IQR 2.8-9.4) in nonprogressors (P < 0.001). In an adjusted model, only 20-HETE independently predicted CKD progression. Each 1 standard deviation increase in 20-HETE was independently associated with 1.45-fold higher odds of progression (95% confidence interval 1.07-1.95; P = 0.017). Principal components of lipoxygenase (LOX) and cytochrome P450 (CYP450) pathways were independently associated with CKD progression. CONCLUSIONS: We found higher odds of CKD progression associated with higher 20-HETE, LOX and CYP450 metabolic pathways. These alterations precede CKD progression and may serve as targets for interventions aimed at halting progression.

Longitudinal Evolution of Markers of Mineral Metabolism in Patients With CKD: The Chronic Renal Insufficiency Cohort (CRIC) Study.

RATIONALE & OBJECTIVE: The pathogenesis of disordered mineral metabolism in chronic kidney disease (CKD) is largely informed by cross-sectional studies of humans and longitudinal animal studies. We sought to characterize the longitudinal evolution of disordered mineral metabolism during the course of CKD. STUDY DESIGN: Retrospective analysis nested in a cohort study. SETTING & PARTICIPANTS: Participants in the Chronic Renal Insufficiency Cohort (CRIC) Study who had up to 5 serial annual measurements of estimated glomerular filtration rate, fibroblast growth factor 23 (FGF-23), parathyroid hormone (PTH), serum phosphate, and serum calcium and who subsequently reached end-stage kidney disease (ESKD) during follow-up (n = 847). EXPOSURE: Years before ESKD. OUTCOMES: Serial FGF-23, PTH, serum phosphate, and serum calcium levels. ANALYTICAL APPROACH: To assess longitudinal dynamics of disordered mineral metabolism in human CKD, we used "ESKD-anchored longitudinal analyses" to express time as years before ESKD, enabling assessments of mineral metabolites spanning 8 years of CKD progression before ESKD. RESULTS: Mean FGF-23 levels increased markedly as time before ESKD decreased, while PTH and phosphate levels increased modestly and calcium levels declined minimally. Compared with other mineral metabolites, FGF-23 levels demonstrated the highest rate of change (velocity: first derivative of the function of concentration over time) and magnitude of acceleration (second derivative). These changes became evident approximately 5 years before ESKD and persisted without deceleration through ESKD onset. Rates of changes in PTH and phosphate levels increased modestly and without marked acceleration around the same time, with modest deceleration immediately before ESKD, when use of active vitamin D and phosphate binders increased. LIMITATIONS: Individuals who entered the CRIC Study at early stages of CKD and who did not progress to ESKD were not studied. CONCLUSIONS: Among patients with progressive CKD, FGF-23 levels begin to increase 5 years before ESKD and continue to rapidly accelerate until transition to ESKD.

Impact of AKI on Urinary Protein Excretion: Analysis of Two Prospective Cohorts.

BACKGROUND: Prior studies of adverse renal consequences of AKI have almost exclusively focused on eGFR changes. Less is known about potential effects of AKI on proteinuria, although proteinuria is perhaps the strongest risk factor for future loss of renal function. METHODS: We studied enrollees from the Assessment, Serial Evaluation, and Subsequent Sequelae of AKI (ASSESS-AKI) study and the subset of the Chronic Renal Insufficiency Cohort (CRIC) study enrollees recruited from Kaiser Permanente Northern California. Both prospective cohort studies included annual ascertainment of urine protein-to-creatinine ratio, eGFR, BP, and medication use. For hospitalized participants, we used inpatient serum creatinine measurements obtained as part of clinical care to define an episode of AKI (i.e., peak/nadir inpatient serum creatinine ≥1.5). We performed mixed effects regression to examine change in log-transformed urine protein-to-creatinine ratio after AKI, controlling for time-updated covariates. RESULTS: At cohort entry, median eGFR was 62.9 ml/min per 1.73 m2 (interquartile range [IQR], 46.9-84.6) among 2048 eligible participants, and median urine protein-to-creatinine ratio was 0.12 g/g (IQR, 0.07-0.25). After enrollment, 324 participants experienced at least one episode of hospitalized AKI during 9271 person-years of follow-up; 50.3% of first AKI episodes were Kidney Disease Improving Global Outcomes stage 1 in severity, 23.8% were stage 2, and 25.9% were stage 3. In multivariable analysis, an episode of hospitalized AKI was independently associated with a 9% increase in the urine protein-to-creatinine ratio. CONCLUSIONS: Our analysis of data from two prospective cohort studies found that hospitalization for an AKI episode was independently associated with subsequent worsening of proteinuria.

Differential network enrichment analysis reveals novel lipid pathways in chronic kidney disease.

MOTIVATION: Functional enrichment testing methods can reduce data comprising hundreds of altered biomolecules to smaller sets of altered biological 'concepts' that help generate testable hypotheses. This study leveraged differential network enrichment analysis methodology to identify and validate lipid subnetworks that potentially differentiate chronic kidney disease (CKD) by severity or progression. RESULTS: We built a partial correlation interaction network, identified highly connected network components, applied network-based gene-set analysis to identify differentially enriched subnetworks, and compared the subnetworks in patients with early-stage versus late-stage CKD. We identified two subnetworks 'triacylglycerols' and 'cardiolipins-phosphatidylethanolamines (CL-PE)' characterized by lower connectivity, and a higher abundance of longer polyunsaturated triacylglycerols in patients with severe CKD (stage ≥4) from the Clinical Phenotyping Resource and Biobank Core. These finding were replicated in an independent cohort, the Chronic Renal Insufficiency Cohort. Using an innovative method for elucidating biological alterations in lipid networks, we demonstrated alterations in triacylglycerols and cardiolipins-phosphatidylethanolamines that precede the clinical outcome of end-stage kidney disease by several years. AVAILABILITY AND IMPLEMENTATION: A complete list of NetGSA results in HTML format can be found at http://metscape.ncibi.org/netgsa/12345-022118/cric_cprobe/022118/results_cric_cprobe/main.html. The DNEA is freely available at https://github.com/wiggie/DNEA. Java wrapper leveraging the cytoscape.js framework is available at http://js.cytoscape.org. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Nonclinical Development of ENV905 (Difluprednate) Ophthalmic Implant for the Treatment of Inflammation and Pain Associated with Ocular Surgery.

PURPOSE: Topical corticosteroids are widely used in the treatment of inflammation and pain after ocular surgery, but they possess several shortcomings, including frequent dosing and low patient adherence. We evaluated the efficacy and pharmacokinetics of ENV905 (difluprednate or DFBA) Ophthalmic Implant, a single-dose drug delivery system, compared with 0.05% Durezol. METHODS: PRINT® technology was used to fabricate ENV905 implants for either intracameral (IC) or subconjunctival (SCJ) delivery of extended-release DFBA. A postoperative inflammation model and ocular pharmacokinetics studies of ENV905 or Durezol were conducted in albino rabbits for a maximum of 12 weeks. RESULTS: Suppression of ocular inflammation was marked for both IC and SJC ENV905 compared with placebo, and it was superior or equivalent to that observed with QID Durezol. Concentrations of desacetyl difluprednate (DFB, active metabolite) peaked on day 1 and tapered over time for ENV905, with IC ENV905 delivering DFB to the target tissue at the time of greatest inflammation, whereas SJC produced a longer duration of exposure. Durezol eyes demonstrated consistent exposure over time with maximal exposure in the cornea. Although the pharmacokinetic profile differed for the two routes, efficacy was similar. CONCLUSION: ENV905 was well tolerated and demonstrated a robust reduction in ocular inflammation with targeted drug delivery. The results from these studies show that ENV905 provides a sustained therapeutic effect after a single dose. By resolving low patient compliance and eliminating the peaks and troughs in drug concentration, sustained drug delivery via ENV905 may further improve the overall control of postoperative inflammation and pain.

Fibroblast Growth Factor 23 and Anemia in the Chronic Renal Insufficiency Cohort Study.

BACKGROUND AND OBJECTIVES: Anemia is an early complication of CKD that is associated with increased morbidity and mortality. Prior data show associations between abnormal mineral metabolism markers and decreased erythropoiesis. However, few studies have investigated elevated fibroblast growth factor 23 as a risk factor for the development of anemia in patients with CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted a prospective cohort study of 3869 individuals with mild to severe CKD enrolled in the Chronic Renal Insufficiency Cohort Study between 2003 and 2008 and followed through 2013. We hypothesized that elevated baseline fibroblast growth factor 23 levels are associated with prevalent anemia, decline in hemoglobin over time, and development of incident anemia, defined as serum hemoglobin level <13 g/dl in men, serum hemoglobin level <12 g/dl in women, or use of erythropoietin stimulating agents. RESULTS: In the 1872 of 3869 individuals who had prevalent anemia at baseline, mean age was 58 (11) years old, and mean eGFR was 39 (13) ml/min per 1.73 m2. Higher levels of fibroblast growth factor 23 were significantly associated with prevalent anemia (odds ratio per 1-SD increase in natural log-transformed fibroblast growth factor 23, 1.39; 95% confidence interval, 1.26 to 1.52), decline in hemoglobin over 4 years, and risk of incident anemia (hazard ratio per 1-SD increase in natural log-transformed fibroblast growth factor 23, 1.13; 95% confidence interval, 1.04 to 1.24; quartile 4 versus quartile 1: hazard ratio, 1.59; 95% confidence interval, 1.19 to 2.11) independent of demographic characteristics, cardiovascular disease risk factors, CKD-specific factors, and other mineral metabolism markers. The results of our prospective analyses remained unchanged after additional adjustment for time-varying eGFR. CONCLUSIONS: Elevated fibroblast growth factor 23 is associated with prevalent anemia, change in hemoglobin over time, and development of anemia. Future studies are needed to elucidate the mechanisms for these associations.

Acid Load and Phosphorus Homeostasis in CKD.

BACKGROUND: The kidneys maintain acid-base homeostasis through excretion of acid as either ammonium or as titratable acids that primarily use phosphate as a buffer. In chronic kidney disease (CKD), ammoniagenesis is impaired, promoting metabolic acidosis. Metabolic acidosis stimulates phosphaturic hormones, parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF-23) in vitro, possibly to increase urine titratable acid buffers, but this has not been confirmed in humans. We hypothesized that higher acid load and acidosis would associate with altered phosphorus homeostasis, including higher urinary phosphorus excretion and serum PTH and FGF-23. STUDY DESIGN: Cross-sectional. SETTING & PARTICIPANTS: 980 participants with CKD enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study. PREDICTORS: Net acid excretion as measured in 24-hour urine, potential renal acid load (PRAL) estimated from food frequency questionnaire responses, and serum bicarbonate concentration < 22 mEq/L. OUTCOME & MEASUREMENTS: 24-hour urine phosphorus and calcium excretion and serum phosphorus, FGF-23, and PTH concentrations. RESULTS: Using linear and log-linear regression adjusted for demographics, kidney function, comorbid conditions, body mass index, diuretic use, and 24-hour urine creatinine excretion, we found that 24-hour urine phosphorus excretion was higher at higher net acid excretion, higher PRAL, and lower serum bicarbonate concentration (each P<0.05). Serum phosphorus concentration was also higher with higher net acid excretion and lower serum bicarbonate concentration (each P=0.001). Only higher net acid excretion associated with higher 24-hour urine calcium excretion (P<0.001). Neither net acid excretion nor PRAL was associated with FGF-23 or PTH concentrations. PTH, but not FGF-23, concentration (P=0.2) was 26% (95% CI, 13%-40%) higher in participants with a serum bicarbonate concentration <22 versus ≥22 mEq/L (P<0.001). Primary results were similar if stratified by estimated glomerular filtration rate categories or adjusted for iothalamate glomerular filtration rate (n=359), total energy intake, dietary phosphorus, or urine urea nitrogen excretion, when available. LIMITATIONS: Possible residual confounding by kidney function or nutrition; urine phosphorus excretion was included in calculation of the titratable acid component of net acid excretion. CONCLUSIONS: In CKD, higher acid load and acidosis associate independently with increased circulating phosphorus concentration and augmented phosphaturia, but not consistently with FGF-23 or PTH concentrations. This may be an adaptation that increases titratable acid excretion and thus helps maintain acid-base homeostasis in CKD. Understanding whether administration of base can lower phosphorus concentrations requires testing in interventional trials.

Risk Factors for Heart Failure in Patients With Chronic Kidney Disease: The CRIC (Chronic Renal Insufficiency Cohort) Study.

BACKGROUND: Heart failure is common in patients with chronic kidney disease. We studied risk factors for incident heart failure among 3557 participants in the CRIC (Chronic Renal Insufficiency Cohort) Study. METHODS AND RESULTS: Kidney function was assessed by estimated glomerular filtration rate (eGFR) using serum creatinine, cystatin C, or both, and 24-hour urine albumin excretion. During an average of 6.3 years of follow-up, 452 participants developed incident heart failure. After adjustment for age, sex, race, and clinical site, hazard ratio (95% CI) for heart failure associated with 1 SD lower creatinine-based eGFR was 1.67 (1.49, 1.89), 1 SD lower cystatin C-based-eGFR was 2.43 (2.10, 2.80), and 1 SD higher log-albuminuria was 1.65 (1.53, 1.78), all P<0.001. When all 3 kidney function measures were simultaneously included in the model, lower cystatin C-based eGFR and higher log-albuminuria remained significantly and directly associated with incidence of heart failure. After adjusting for eGFR, albuminuria, and other traditional cardiovascular risk factors, anemia (1.37, 95% CI 1.09, 1.72, P=0.006), insulin resistance (1.16, 95% CI 1.04, 1.28, P=0.006), hemoglobin A1c (1.27, 95% CI 1.14, 1.41, P<0.001), interleukin-6 (1.15, 95% CI 1.05, 1.25, P=0.002), and tumor necrosis factor-α (1.10, 95% CI 1.00, 1.21, P=0.05) were all significantly and directly associated with incidence of heart failure. CONCLUSIONS: Our study indicates that cystatin C-based eGFR and albuminuria are better predictors for risk of heart failure compared to creatinine-based eGFR. Furthermore, anemia, insulin resistance, inflammation, and poor glycemic control are independent risk factors for the development of heart failure among patients with chronic kidney disease.

Qualification and application of a liquid chromatography-tandem mass spectrometric method for the determination of human Aß1-40 and Aß1-42 peptides in transgenic mouse plasma using micro-elution solid phase extraction.

A liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed and applied for the determination of human Aß1-40 and Aß1-42 peptides in transgenic mouse plasma to support preclinical pharmacodynamics studies. The method consisted of micro-elution solid phase extraction for sample preparation and LC-MS/MS analysis in the negative ion mode using electrospray ionization for analysis. (15)N53-Aß1-40 and (15)N55-Aß1-42 peptides were used as internal standards. A quadratic regression (weighted 1/concentrations), with an equation y = ax(2) + bx + c, was used to fit calibration curves over the concentration range of 0.500-100 ng/mL for both Aß1-40 and Aß1-42 peptides. For quality control samples at 6.00, 40.0 and 80.0 ng/mL from the qualification experiment, the within-run accuracy ranged from -2.69 to 0.583 % with precision values ≤8.23 % for Aß1-40. Within-run accuracy ranged from -4.83 to 10.1 % with precision values ≤8.87 % for Aß1-42. Samples from a pharmacodynamics study using Tg2576 transgenic mice were analyzed by this qualified LC-MS/MS method and concentrations were compared to those generated by ELISA. The two methods were shown to be comparable for Aß1-40 quantification of samples from the Tg2576 amyloid precursor protein transgenic mouse model, but varied slightly for Aß1-42.

Factors predicting vitamin D response variation in non-Hispanic white postmenopausal women.

OBJECTIVE: It is well documented that there is wide variation in the response of serum 25-hydroxyvitamin D [25(OH)D] to a given dose of vitamin D supplementation. Understanding factors affecting the response variation is important for identifying subjects who are susceptible to vitamin D deficiency or toxicity. This study aimed to evaluate potential predictors for vitamin D response variation. DESIGN AND PARTICIPANTS: A total of 1179 non-Hispanic white postmenopausal women were enrolled into a 4-yr calcium and vitamin D (1100 IU/d) clinical trial. Among them, serum 25(OH)D level of 1063 subjects were measured at both baseline and after 12 months treatment. Vitamin D response was computed for these 1063 subjects as the difference in levels of serum 25(OH)D concentration at the end of a 12-month vitamin D treatment compared with baseline. Stepwise linear regression was used to identify predictors of vitamin D response variation. RESULTS: Increase in vitamin D intake, baseline serum 25(OH)D level, baseline blood collection season, baseline serum calcium level, and baseline body mass index were predictors of vitamin D response variation. These five factors explained 46.8% of the vitamin D response variation in the 1063 subjects. The first three factors [increase in vitamin D intake, baseline serum 25(OH)D level, baseline blood collection season] remained as predictors in the 392 subjects with trial vitamin D supplementation. For the first time, our study indicated that season is an important prediction factor for vitamin D response variation. Subjects who started vitamin D treatment in a cold season (autumn and winter) achieved a significantly higher serum 25(OH)D increase than those started in a hot season (summer) (P < 0.001). CONCLUSION: Our study suggests that the increase in vitamin D supplementation, baseline serum 25(OH)D level, and the season when initiating the vitamin D supplementation can partially predict vitamin D response variation in non-Hispanic postmenopausal women.

Measured GFR does not outperform estimated GFR in predicting CKD-related complications.

Although many assume that measurement of glomerular filtration rate (GFR) using a marker such as iothalamate (iGFR) is superior to equation-estimated GFR (eGFR), each of these methods has distinct disadvantages. Because physicians often use renal function to guide the screening for various CKD-associated complications, one method to compare the clinical utility of iGFR and eGFR is to determine the strength of their association with CKD-associated comorbidities. Using a subset of 1214 participants in the Chronic Renal Insufficiency Cohort (CRIC) Study, we determined the cross-sectional associations between known complications of CKD and iGFR, eGFR estimated from serum creatinine (eGFR_Cr), and eGFR estimated from cystatin C (eGFR_cysC). We found that none of the measures of renal function strongly associated with CKD complications and that the relative strengths of associations varied according to the outcome of interest. For example, iGFR demonstrated better discrimination than eGFR_Cr and eGFR_cysC for outcomes of anemia and hemoglobin concentration; however, both eGFR_Cr and eGFR_cysC demonstrated better discrimination than iGFR for outcomes of hyperphosphatemia and phosphorus level. iGFR and eGFR had similar strengths of association with hyperkalemia/potassium level and with metabolic acidosis/bicarbonate level. In conclusion, iothalamate measurement of GFR is not consistently superior to equation-based estimations of GFR in explaining CKD-related comorbidities. These results raise questions regarding the conventional view that iGFR is the "gold standard" measure of kidney function.

Thiazide and loop diuretics.

KEY POINTS AND PRACTICAL RECOMMENDATIONS: • Although chlorthalidone and hydrochlorothiazide are structurally similar, they are very different pharmacokinetically, with chlorthalidone having both an extremely long half-life (approximately 40 to 60 hours) and a large volume of distribution, with gradual elimination from the plasma compartment by tubular secretion. • Furosemide usage, the most widely used diuretic in the loop diuretic class, can be complicated by extremely erratic absorption, with a bioavailability range of 12% to 112%. • Chlorthalidone, at a dose of 25 mg, is comparatively more potent than 50 mg of hydrochlorothiazide, particularly as related to overnight blood pressure reduction. • In ALLHAT, there was no difference among chlorthalidone, amlodipine, lisinopril, and doxazosin for the primary outcome or mortality. • Secondary outcomes were similar except for a 38% higher rate of heart failure with amlodipine; a 10% higher rate of combined cardiovascular disease, a 15% higher rate of stroke, and a 19% higher rate of heart failure with lisinopril; and a 20% higher rate of cardiovascular disease, a 20% higher rate of stroke (40% higher rate in blacks), and an 80% higher rate of heart failure with doxazosin, compared with chlorthalidone. • The ACCOMPLISH study may affect future practice guidelines as a result of its findings favoring the amlodipine/benazepril combination; however, the generalizability to patient populations with a lesser cardiovascular risk profile remains in question and the dose of hydrochlorothiazide was only 12.5 mg to 25 mg daily, which was a dose lower than that used in placebo-controlled trials using hydrochlorothiazide. • Certain low-renin patient groups (eg, blacks, the elderly, and diabetics) as well as those who manifest the metabolic syndrome are commonly more responsive to thiazide-type diuretic therapy. • Diuretics can be successfully combined with ß-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, centrally acting agents, and even calcium channel blockers. • Although thiazide-type diuretics are among the best-tolerated antihypertensive agents in terms of symptomatic adverse effects, diuretic-related adverse side effects include those with established mechanisms (eg, such as electrolyte changes and/or metabolic abnormalities) and other side effects, which are less well understood mechanistically (eg, impotence), although the latter is not universally accepted as a diuretic-related side effect. • Thiazide-induced hypokalemia is associated with increased blood glucose, and treatment of thiazide-induced hypokalemia may reverse glucose intolerance and possibly prevent diabetes. • Thiazide-induced hyperuricemia occurs as a result of volume contraction and competition with uric acid for renal tubular secretion, but does not necessarily contraindicate using a thiazide, especially if a uric acid-lowering drug such as allopurinol is being used. • Adverse interactions include the blunting of thiazide effects by nonsteroidal anti-inflammatory drugs and the potential to increase fatigue, lethargy, and increase in glucose when combined with ß-blockers. • Thiazide-type diuretics are useful first-line agents in the treatment of hypertension because they have been proven to reduce cardiovascular mortality and morbidity in systolic and diastolic forms of hypertension and do so at low cost. • Loop diuretics should not be used as first-line therapy in hypertension since there are no outcome data with them. They should be reserved for conditions of clinically significant fluid overload (eg, heart failure and significant fluid retention with vasodilator drugs, such as minoxidil) or with advanced renal failure and can be combined with thiazide-type diuretics.

Fibroblast growth factor 23 is elevated before parathyroid hormone and phosphate in chronic kidney disease.

Fibroblast growth factor 23 (FGF23) regulates phosphorus metabolism and is a strong predictor of mortality in dialysis patients. FGF23 is thought to be an early biomarker of disordered phosphorus metabolism in the initial stages of chronic kidney disease (CKD). We measured FGF23 in baseline samples from 3879 patients in the Chronic Renal Insufficiency Cohort study, which is a diverse cohort of patients with CKD stage 2-4. Mean serum phosphate and median parathyroid hormone (PTH) levels were in the normal range, but median FGF23 was markedly greater than in healthy populations, and increased significantly with decreasing estimated glomerular filtration rate (eGFR). High levels of FGF23, defined as being above 100 RU/ml, were more common than secondary hyperparathyroidism and hyperphosphatemia in all strata of eGFR. The threshold of eGFR at which the slope of FGF23 increased was significantly higher than the corresponding threshold for PTH based on non-overlapping 95% confidence intervals. Thus, increased FGF23 is a common manifestation of CKD that develops earlier than increased phosphate or PTH. Hence, FGF23 measurements may be a sensitive early biomarker of disordered phosphorus metabolism in patients with CKD and normal serum phosphate levels.

Comparative performance of the CKD Epidemiology Collaboration (CKD-EPI) and the Modification of Diet in Renal Disease (MDRD) Study equations for estimating GFR levels above 60 mL/min/1.73 m2.

BACKGROUND: The Modification of Diet in Renal Disease (MDRD) Study equation underestimates measured glomerular filtration rate (GFR) at levels>60 mL/min/1.73 m2, with variable accuracy among subgroups; consequently, estimated GFR (eGFR)>or=60 mL/min/1.73 m2 is not reported by clinical laboratories. Here, performance of a more accurate GFR-estimating equation, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, is reported by level of GFR and clinical characteristics. STUDY DESIGN: Test of diagnostic accuracy. SETTING & PARTICIPANTS: Pooled data set of 3,896 people from 16 studies with measured GFR (not used for the development of either equation). Subgroups were defined by eGFR, age, sex, race, diabetes, prior solid-organ transplant, and body mass index. INDEX TESTS: eGFR from the CKD-EPI and MDRD Study equations and standardized serum creatinine. REFERENCE TEST: Measured GFR using urinary or plasma clearance of exogenous filtration markers. RESULTS: Mean measured GFR was 68+/-36 (SD) mL/min/1.73 m2. For eGFR<30 mL/min/1.73 m2, both equations have similar bias (median difference compared with measured GFR). For eGFR of 30-59 mL/min/1.73 m2, bias was decreased from 4.9 to 2.1 mL/min/1.73 m2 (57% improvement). For eGFR of 60-89 mL/min/1.73 m2, bias was decreased from 11.9 to 4.2 mL/min/1.73 m2 (61% improvement). For eGFR of 90-119 mL/min/1.73 m2, bias was decreased from 10.0 to 1.9 mL/min/1.73 m2 (75% improvement). Similar or improved performance was noted for most subgroups with eGFR<90 mL/min/1.73 m2, other than body mass index<20 kg/m2, with greater variation noted for some subgroups with eGFR>or=90 mL/min/1.73 m2. LIMITATIONS: Limited number of elderly people and racial and ethnic minorities with measured GFR. CONCLUSIONS: The CKD-EPI equation is more accurate than the MDRD Study equation overall and across most subgroups. In contrast to the MDRD Study equation, eGFR>or=60 mL/min/1.73 m2 can be reported using the CKD-EPI equation.

Wolman disease/cholesteryl ester storage disease: efficacy of plant-produced human lysosomal acid lipase in mice.

Lysosomal acid lipase (LAL) is an essential enzyme that hydrolyzes triglycerides (TGs) and cholesteryl esters (CEs) in lysosomes. Genetic LAL mutations lead to Wolman disease (WD) and cholesteryl ester storage disease (CESD). An LAL-null (lal(-/-)) mouse model resembles human WD/CESD with storage of CEs and TGs in multiple organs. Human LAL (hLAL) was expressed in Nicotiana benthamiana using the GENEWARE expression system (G-hLAL). Purified G-hLAL showed mannose receptor-dependent uptake into macrophage cell lines (J774E). Intraperitoneal injection of G-hLAL produced peak activities in plasma at 60 min and in the liver and spleen at 240 min. The t(1/2) values were: approximately 90 min (plasma), approximately 14 h (liver), and approximately 32 h (spleen), with return to baseline by approximately 150 h in liver and approximately 200 h in spleen. Ten injections of G-hLAL (every 3 days) into lal(-/-) mice produced normalization of hepatic color, decreases in hepatic cholesterol and TG contents, and diminished foamy macrophages in liver, spleen, and intestinal villi. All injected lal(-/-) mice developed anti-hLAL protein antibodies, but suffered no adverse events. These studies demonstrate the feasibility of using plant-expressed, recombinant hLAL for the enzyme therapy of human WD/CESD with general implications for other lysosomal storage diseases.