A simple electronic alert for acute kidney injury.

BACKGROUND: Acute kidney injury (AKI) is frequently under-recognized and contributes to poor outcomes. Electronic alerts (e-alerts) to highlight AKI based on changes in serum creatinine may facilitate earlier recognition and treatment, and sophisticated algorithms for AKI detection have been proposed or implemented elsewhere. However, many laboratories currently lack the resources or capability to replicate these systems. METHODS: A real-time automated delta check e-alert flags a 50% increase in creatinine to a concentration of >50 µmol/L from the most recent result within a 90-day period and automatically adds the comment '?AKI - creatinine increase >50% from previous' with a link to local AKI guidelines. In addition, creatinine results >300 µmol/L are retrospectively reviewed and phoned if AKI is suspected. For each alert over a 12-day period we manually reviewed previous and subsequent creatinine results to determine baseline creatinine and stage AKI according to Acute Kidney Injury Network (AKIN) criteria. RESULTS: From 11,930 creatinine requests, 63 of 90 (70%) delta check e-alerts were due to AKI, identifying 61 episodes of AKI. Thirty four of 54 (63%) creatinine results >300 µmol/L were due to AKI, identifying a further 10 episodes of AKI. The positive predictive value (PPV) for AKI of a delta check e-alert was greater when the trigger creatinine was >100 µmol/L (PPV 89%) or when the absolute change in creatinine was >50 µmol/L (PPV 93%). CONCLUSION: This study demonstrates that a simple automated delta check can detect and flag AKI in real time, continuously, at little extra cost and without manual input.

Enhanced 3-epi-25-hydroxyvitamin D3 signal leads to overestimation of its concentration and amplifies interference in 25-hydroxyvitamin D LC-MS/MS assays.

BACKGROUND: 3-epi-25-hydroxyvitamin D3 (3-epi-25OHD3) interferes in most liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays for 25-hydroxyvitamin D (25OHD). The clinical significance of this is unclear, with concentrations from undetectable to 230 nmol/L reported. Many studies have quantified 3-epi-25OHD3 based on 25OHD3 calibrators or other indirect methods, and we speculated that this contributes to the observed variability in reported 3-epi-25OHD3 concentrations. METHODS: We compared continuous MS/MS infusions of 3-epi-25OHD3 and 25OHD3 solutions, spiked both analytes into the same serum matrix and analysed patient samples to assess the effect of three different quantitation methods on 3-epi-25OHD3 concentration. Experiments were performed on an LC-MS/MS system using a phenyl column which does not resolve 3-epi-25OHD3, and a modified method utilizing a Zorbax SB-CN column that chromatographically resolves 3-epi-25OHD3 from 25OHD3. RESULTS: A greater 3-epi-25OHD3 signal, compared with 25OHD3, was observed during equimolar post-column continuous infusion of analyte solutions, and following analysis of a serum pool spiked with both analytes. 3-epi-25OHD3 signal enhancement was dependent on mobile phase composition. Compared with 3-epi-25OHD3 calibrators, indirect quantitation methods resulted in up to 10 times as many samples having 3-epi-25OHD3 concentrations ≥ 10 nmol/L, and an approximately fourfold increase in the maximum observed 3-epi-25OHD3 concentration to 95 nmol/L. CONCLUSIONS: Enhanced 3-epi-25OHD3 signal leads to overestimation of its concentrations in the indirect quantitation methods used in many previous studies. The enhanced signal may contribute to greater interference in some 25OHD LC-MS/MS assays than others. We highlight that equimolar responses cannot be assumed in LC-MS/MS systems, even if two molecules are structurally similar.

Autoantibodies to MUC1 glycopeptides cannot be used as a screening assay for early detection of breast, ovarian, lung or pancreatic cancer.

BACKGROUND: Autoantibodies have been detected in sera before diagnosis of cancer leading to interest in their potential as screening/early detection biomarkers. As we have found autoantibodies to MUC1 glycopeptides to be elevated in early-stage breast cancer patients, in this study we analysed these autoantibodies in large population cohorts of sera taken before cancer diagnosis. METHODS: Serum samples from women who subsequently developed breast cancer, and aged-matched controls, were identified from UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) and Guernsey serum banks to formed discovery and validation sets. These were screened on a microarray platform of 60mer MUC1 glycopeptides and recombinant MUC1 containing 16 tandem repeats. Additional case-control sets comprised of women who subsequently developed ovarian, pancreatic and lung cancer were also screened on the arrays. RESULTS: In the discovery (273 cases, 273 controls) and the two validation sets (UKCTOCS 426 cases, 426 controls; Guernsey 303 cases and 606 controls), no differences were found in autoantibody reactivity to MUC1 tandem repeat peptide or glycoforms between cases and controls. Furthermore, no differences were observed between ovarian, pancreatic and lung cancer cases and controls. CONCLUSION: This robust, validated study shows autoantibodies to MUC1 peptide or glycopeptides cannot be used for breast, ovarian, lung or pancreatic cancer screening. This has significant implications for research on the use of MUC1 in cancer detection.

Early detection of cancer in the general population: a blinded case-control study of p53 autoantibodies in colorectal cancer.

BACKGROUND: Recent reports from cancer screening trials in high-risk populations suggest that autoantibodies can be detected before clinical diagnosis. However, there is minimal data on the role of autoantibody signatures in cancer screening in the general population. METHODS: Informative p53 peptides were identified in sera from patients with colorectal cancer using an autoantibody microarray with 15-mer overlapping peptides covering the complete p53 sequence. The selected peptides were evaluated in a blinded case-control study using stored serum from the multimodal arm of the United Kingdom Collaborative Trial of Ovarian Cancer Screening where women gave annual blood samples. Cases were postmenopausal women who developed colorectal cancer following recruitment, with 2 or more serum samples preceding diagnosis. Controls were age-matched women with no history of cancer. RESULTS: The 50 640 women randomised to the multimodal group were followed up for a median of 6.8 (inter-quartile range 5.9-8.4) years. Colorectal cancer notification was received in 101 women with serial samples of whom 97 (297 samples) had given consent for secondary studies. They were matched 1 : 1 with 97 controls (296 serial samples). The four most informative peptides identified 25.8% of colorectal cancer patients with a specificity of 95%. The median lead time was 1.4 (range 0.12-3.8) years before clinical diagnosis. CONCLUSION: Our findings suggest that in the general population, autoantibody signatures are detectable during preclinical disease and may be of value in cancer screening. In colorectal cancer screening in particular, where the current need is to improve compliance, it suggests that p53 autoantibodies may contribute towards risk stratification.

Histological confirmation of breast cancer registration and self-reporting in England and Wales: a cohort study within the UK Collaborative Trial of Ovarian Cancer Screening.

BACKGROUND: In research studies, accurate information of cancer diagnosis is crucial. In women with breast cancer (BC), we compare cancer registration (CR) in England/Wales and self-reporting with independent confirmation. METHODS: In the UK Collaborative Trial of Ovarian Cancer Screening, notification of BC diagnosed between randomisation and 31 December 2009 was obtained through (1) CR (17 October 2011) and (2) self-reporting using postal-questionnaire. Breast cancer was confirmed using a detailed questionnaire (BC questionnaire BCQ) completed by the treating clinician (gold standard). Apparent sensitivity and positive-predictive value of CR/self-reporting vs BCQ were calculated. RESULTS: Of 1065 women with possible BC notification, diagnosis was confirmed in 932 (87.5%). A total of 3.1% (28 out of 918) of BC CR and 12.4% (128 out of 1032) of women with self-reported BC only had in-situ carcinoma on BCQ. Another 4.6% (43 out of 932) of BCQ-confirmed cancer did not have a BC registration, and 3.6% (34 out of 932) did not self-report BC. Apparent sensitivity of CR and self-reporting vs BCQ were 95.4 and 96.4%, respectively. Positive-predictive value of self-reporting (87.1%) was significantly lower than that of CR (96.8%). Women aged<65 were more likely to over report in-situ carcinoma as BC. Overall, 73 (6.8%) women would have been misclassified/missed if CR, and 167 (15.6%) if self-reporting data alone was used. CONCLUSION: This study confirms the reliability of BC registration in England/Wales and highlights the fact that 1 in 10 women self-reporting BC might only have in-situ breast carcinoma.

Spironolactone interference in the immunoassay of androstenedione.

BACKGROUND: In an evaluation of androstenedione results from patient serum samples using the Siemens Immulite 2500 analyser and manual Coat-A-Count (CAC) methods, three outliers were evident with grossly elevated results in the CAC assay. METHODS: The clinic notes of three patients with apparently high serum androstenedione concentrations by the CAC assay were checked for medications. The samples were all from patients with polycystic ovary syndrome taking 100-200 mg/d of a steroidal antiandrogen (spironolactone). Two other patients on 50 mg spironolactone per day had less markedly higher androstendione results with the CAC assay. In a further five patients who were selected since they were on spironolactone and had high androstenedione results by the CAC method, spironolactone was temporarily withdrawn and fresh blood samples obtained for analysis. RESULTS: Spironolactone treatment was associated with higher androstenedione concentrations measured by the CAC assay that reverted to normal on treatment withdrawal. Based on a single test with spironolactone at 1000 ng/mL, the manufacturer reported only 0.109% interference in the CAC assay. CONCLUSIONS: Spironolactone (and/or its metabolites) may interfere in the Siemens CAC assay for androstenedione but not in the Immulite 2500 assay. This experience highlights the need for information from clinicians on drug treatment when laboratory investigations are requested. Drug interferences in immunoassay are common and need evaluation beyond tests performed to certify laboratory reagents.

Serum oestrogen receptor alpha and beta bioactivity are independently associated with breast cancer: a proof of principle study.

BACKGROUND: Oestrogens play a crucial role in breast carcinogenesis. Earlier studies have analysed the serum levels of endogenous hormones measured by conventional assays. In this study, we analysed the capacity of serum from breast cancer cases and controls to transactivate the oestrogen receptor alpha (ER-alpha) and beta (ER-beta). METHODS: We used a receptor oestrogen-responsive element (ERE) -- the green fluorescent protein (GFP)-reporter test system in Saccharomyces cerevisiae. Oestrogen receptor-alpha or ER-beta bioactivity was determined in serum from 182 randomly chosen postmenopausal women with breast cancer and from 188 age-matched controls. RESULTS: High serum ER-alpha and ER-beta bioactivity were independently associated with the presence of breast cancer. Women whose levels of serum ER-alpha and ER-beta bioactivity were in the highest quintile among controls had a 7.57-(95% confidence interval (CI): 2.46-23.32; P=0.0004) and a 10.14 (95% CI: 3.19-32.23; P<0.0001)-fold risk for general and oestrogen receptor-positive breast cancer, respectively. CONCLUSION: The use of serum ER-alpha and ER-beta bioactivity assays as clinical tools in the management of breast cancer warrants further research. Future studies will dictate whether surrogate markers of ER-alpha and ER-beta bioactivity will provide a means to monitor the efficacy of anti-endocrine, adjuvant and chemopreventive strategies.

Systematic review on urine albumin testing for early detection of diabetic complications.

OBJECTIVES: To determine whether microalbuminuria is an independent prognostic factor for the development of diabetic complications and whether improved glycaemic or blood pressure control has a greater influence on the development of diabetic complications in those with microalbuminuria than in those with normoalbuminuria. DATA SOURCES: Electronic databases up until January 2002. REVIEW METHODS: A protocol for peer review by an external expert panel was prepared that included selection criteria for data extraction and required two independent reviewers to undertake article selection and review. Completeness was assessed using hand-searching of major journals. Random effects meta-analysis was used to obtain combined estimates of relative risk (RR). Funnel plots, trim and fill methods and meta-regression were used to assess publication bias and sources of heterogeneity. RESULTS: In patients with type 1 or type 2 DM and microalbuminuria there is a RR of all-cause mortality of 1.8 [95% confidence interval (CI) 1.5 to 2.1] and 1.9 (95% CI 1.7 to 2.1) respectively. Similar RRs were found for other mortality end-points, with age of cohort being inversely related to the RR in type 2 DM. In patients with type 1 DM, there is evidence that microalbuminuria or raised albumin excretion rate has only weak, if any, independent prognostic significance for the incidence of retinopathy and no evidence that it predicts progression of retinopathy, although strong evidence exists for the independent prognostic significance of microalbuminuria or raised albumin excretion rate for the development of proliferative retinopathy (crude RR of 4.1, 95% CI 1.8 to 9.4). For type 2 DM, there is no evidence of any independent prognostic significance for the incidence of retinopathy and little, if any, prognostic relationship between microalbuminuria and the progression of retinopathy or development of proliferative retinopathy. In patients with type 1 DM and microalbuminuria there is an RR of developing end-stage renal disease (ESRD) of 4.8 (95% CI 3.0 to 7.5) and a higher RR (7.5, 95% CI 5.4 to 10.5) of developing clinical proteinuria, with a significantly greater fall in glomerular filtration rate (GFR) in patients with microalbuminuria. In patients with type 2 DM, similar RRs were observed: 3.6 (95% CI 1.6 to 8.4) for developing ESRD and 7.5 (95% CI 5.2 to 10.9) for developing clinical proteinuria, with a significantly greater decline in GFR in the microalbuminuria group of 1.7 (95% CI 0.1 to 3.2) ml per minute per year compared with those who were normoalbuminuric. In adults with type 1 or type 2 DM and microalbuminuria at baseline, the numbers progressing to clinical proteinuria (19% and 24%, respectively) and those regressing to normoalbuminuria (26% and 18%, respectively) did not differ significantly. In children with type 1 DM, regression (44%) was significantly more frequent than progression (15%). In patients with type 1 or type 2 DM and microalbuminuria, there is scarce evidence as to whether improved glycaemic control has any effect on the incidence of cardiovascular disease (CVD), the incidence or progression of retinopathy, or the development of renal complications. However, among patients not stratified by albuminuria, improved glycaemic control benefits retinal and renal complications and may benefit CVD. In the effects of angiotensin-converting enzyme (ACE) inhibitors on GFR in normotensive microalbuminuric patients with type 1 DM, there was no evidence of a consistent treatment effect. There is strong evidence from 11 trials in normotensive type 1 patients with microalbuminuria of a beneficial effect of ACE inhibitor treatment on the risk of developing clinical proteinuria and on the risk of regression to normoalbuminuria. Patients with type 2 DM and microalbuminuria, whether hypertensive or not, may obtain additional cardiovascular benefit from an ACE inhibitor and there may be a beneficial effect on the development of retinopathy in normotensive patients irrespective of albuminuria. There is limited evidence that treatment of hypertensive microalbuminuric type 2 diabetic patients with blockers of the renin--angiotensin system is associated with preserved GFR, but also evidence of no differences in GFR in comparisons with other antihypertensive agents. The data on GFR in normotensive cohorts are inconclusive. In normotensive type 2 patients with microalbuminuria there is evidence from three trials (all enalapril) of a reduction in risk of developing clinical proteinuria; in hypertensive patients there is evidence from one placebo-controlled trial (irbesartan) of a reduction in this risk. Intensive compared with moderate blood pressure control did not affect the rate of progression of microalbuminuria to clinical proteinuria in the one available study. There is inconclusive evidence from four trials of any difference in the proportions of hypertensive patients progressing from microalbuminuria to clinical proteinuria when ACE inhibitors are compared with other antihypertensive agents, and in one trial regression was two-fold higher with lisinopril than with nifedipine. CONCLUSIONS: The most pronounced benefits of glycaemic control identified in this review are on retinal and renal complications in both normoalbuminuric and microalbuminuric patients considered together, with little or no evidence of any greater benefit in those with microalbuminuria. Hence, microalbuminuric status may be a false boundary when considering the benefits of glycaemic control. Classification of a person as normoalbuminuric must not serve to suggest that they will derive less benefit from optimal glycaemic control than a person who is microalbuminuric. All hypertensive patients benefit from blood pressure lowering and there is little evidence of additional benefit in those with microalbuminuria. Antihypertensive therapy with an ACE inhibitor in normotensive patients with microalbuminuria is beneficial. Monitoring microalbuminuria does not have a proven role in modulating antihypertensive therapy while the patient remains hypertensive. Recommendations for microalbuminuria research include: determining rate and predictors of development and factors involved in regression; carrying out economic evaluations of different screening strategies; investigating the effects of screening on patients; standardising screening tests to enable use of common reference ranges; evaluating the effects of lipid-lowering therapy; and using to modulate antihypertensive therapy.

Advanced glycation end product free adducts are cleared by dialysis.

Plasma advanced glycation end product (AGE) free adducts are increased up to 50-fold among patients on dialysis. We examined the ability of hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) to clear these compounds. The AGE free adducts Nepsilon-carboxymethyl-lysine (CML) and Nepsilon-(1-carboxyethyl)lysine (CEL) and the hydroimidazolones derived from glyoxal (G-H1), methylglyoxal (MG-H1), and 3-deoxyglucosone (3DG-H) were determined by LC-MS/MS and pentosidine by HPLC with fluorimetric detection in ultrafiltrates of plasma, urine, or PD effluent as appropriate from patients on HD (n = 8) or PD (n = 8), and from healthy controls (n = 8). Among patients on HD, all free AGEs predialysis were significantly higher than in controls and were decreased with dialysis. The removal of MG-H1 and 3DG-H was comparable to that of urea, whereas that of CML and pentosidine was some 20% higher; in contrast, the removal of CEL and G-H1 was 25% lower. Among patients on CAPD, free AGEs in PD effluent increased with increasing dwell time. The combined renal and peritoneal 24-h excretion rates of CML (4.7 micromol), CEL (6.5 micromol), 3DG-H (16.6 micromol), and pentosidine (0.08 micromol) were twofold higher than the amount excreted in healthy controls, whereas MG-H1 was ninefold higher (59 micromol); the combined clearances of all free AGEs except pentosidine were lower than in healthy controls. Impaired renal clearance contributes to increased plasma free AGEs in uremia, but the increased excretion rate among patients on PD demonstrates that there was also an increased synthesis of free AGEs. Both HD and PD are able to remove free AGEs.

Renal clearance of glycation adducts: anti-glycation defence in uraemia and dialysis.

Increased plasma concentrations of free AGEs (advanced glycation end products) in uraemia are due to impaired renal clearance exacerbated by dietary load and breakdown of the elevated protein-bound AGEs. Increased protein-bound AGEs most probably reflect increased synthesis due to the increased oxidative and carbonyl stress of uraemia, which is exacerbated by the dialysis procedure. Use of biocompatible peritoneal dialysis fluids and haemodialysis membranes will be beneficial, but strategies to further reduce AGE formation are required. These should focus on the hydroimidazalone AGEs, which are quantitatively the most important, and not only on the conventionally monitored AGEs N (epsilon)-carboxymethyl-lysine and pentosidine.

Removal of advanced glycation end products in clinical renal failure by peritoneal dialysis and haemodialysis.

AGEs (advanced glycation end products) accumulate markedly in the plasma of human subjects with renal failure. We investigated the efficiency of removal of AGEs from the circulation by PD (peritoneal dialysis) and HD (haemodialysis) therapy. Free AGEs were measured by LC-MS/MS in blood plasma before dialysis, in dialysis fluid effusate after a 2-12 h dwell time in the peritoneal cavity of PD subjects, and in the HD dialysate before and after HD therapy. In clinical uraemia, the concentrations of free AGEs in blood plasma were increased up to 50-fold. For example, levels of MG-H1 (methylglyoxal-derived hydroimidazolone) were: normal controls, 110+/-46 nM; PD subjects, 1876+/-676 ( P <0.01); HD subjects, 5496+/-1138 nM ( P <0.001). In PD subjects, the AGE concentration in the effusate increased with increasing dwell time, reaching a maximum at a concentration higher than that in plasma for some AGEs at 4-12 h. This may reflect AGE formation in the peritoneal cavity. In HD, AGE concentrations in HD fluid were decreased markedly from the start to the end of a dialysis session, except that levels of the methylglyoxal-derived AGEs N (epsilon)-(1-carboxyethyl)lysine and MG-H1, and of pentosidine, remained 5-fold higher than control levels. Inadequate clearance of free AGEs may be linked to the increased risk of cardiovascular disease in patients with renal failure.

Plasma OLC is elevated in mild experimental uremia but is not associated with hypertension.

BACKGROUND: Little is known about the renal handling of endogenous ouabain-like compound (OLC). The aim of this study was to determine the normal renal clearance of OLC and the effect of mild experimental uremia on plasma OLC and its clearance. METHODS: Male Wistar rats were studied 8 weeks after subtotal (5/6th) nephrectomy (n = 8) and compared with a control sham-operated group (n = 8). RESULTS: Plasma creatinine and OLC were higher in uremic animals compared with controls (creatinine 76+/-5.6 micromol/L v 45+/-9.6 micromol/L, respectively, P < .00005; OLC 195+/-62 pmol/L v 121+/-62 pmol/L, P < .02). Creatinine clearance and OLC clearance were lower in uremic animals compared with controls (creatinine 1.06+/-0.12 mL/min v 1.58+/-0.32 mL/min, respectively, P < .002; OLC 23.6+/-10.4 microL/min v 33.2+/-11.4 microL/min, P < .05). There were no significant differences (all P > .05) between the uremic and control groups in the fractional clearance of OLC (uremic 2.3%+/-1.0% v control 2.2%+/-1.0%), OLC excretion rate (uremic 6.2+/-2.4 pmol/24 h v control 5.0+/-1.1 pmol/24 h) or in the mean systolic blood pressure (BP) (uremic 132+/-13 mm Hg v control 126+/-3 mm Hg). The amount of OLC excreted per unit of functioning nephron mass was 78% higher in uremic animals than in controls. The rate of tubular absorption varied linearly with filtered load, did not differ between groups, and showed no evidence of saturation. CONCLUSIONS: The kidneys are an important excretion route for plasma OLC and moderate but significant increases may occur without inducing hypertension in the short term. The low fractional clearance of OLC is most likely due to tubular absorption and/or catabolism.

Analysis of human ouabainlike compound by micellar electrokinetic chromatography.

In this preliminary study we have optimised micellar electrokinetic chromatography (MEKC, a form of capillary electrophoresis) to enable the chromatographic and spectral characteristics of human ouabainlike compound (OLC) to be investigated. Sera from fifty patients were combined to form a pool (100 ml) whilst urine (92.5 ml) was obtained from a normal healthy volunteer. Both samples were initially concentrated and partially purified by solid phase extraction before further purification by sequential HPLC separations. Final volumes for both extracts were 100 microl. MEKC was performed on a HP(3D) CE instrument with voltage set at 20 KV, capillary temperature at 20 degrees C, injection time 4 s, sample volume 10 nl, with detection by photodiode array. A compound was found in both serum and urine that had similar elution and spectral characteristics to authentic ouabain. We conclude that MEKC is potentially a useful tool for the analysis of human OLC.

Mass spectrometric monitoring of albumin in uremia.

BACKGROUND: Advanced glycation end products (AGEs) are a novel class of uremic toxins. In plasma, they are present in proteins and also in low molecular mass peptides. AGE-modified peptides are thought to bind and modify plasma proteins. Monitoring of the consequent increase in molecular mass of serum albumin may be used in surveillance of the clinical management of uremia. METHODS: We investigated molecular mass changes of human serum albumin (HSA) glycated by glucose and methylglyoxal in vitro and of subjects with moderate renal impairment, end-stage renal disease (ESRD), ESRD on hemodialysis, and normal healthy controls by matrix-assisted laser desorption ionization mass spectrometry. RESULTS: Fatty acid-free HSA had a molecular mass of 66,446 +/- 114 D. Mean (+/-SD) molecular mass increases were HSA minimally glycated by glucose 399 +/- 88 D (N = 5, P < 0.001), HSA highly glycated by glucose 6780 +/- 122 D (N = 5, P < 0.001), HSA minimally glycated by methylglyoxal 73 +/- 121 D (N = 5, P > 0.05), and HSA without fatty acid removal 535 +/- 90 D (N = 5, P < 0.001). For HSA of human subjects, mean (+/- SD) molecular mass increases were normal healthy controls 243 +/- 97 D (N = 5), moderate renal impairment 350 +/- 83 D (P > 0.05 with respect to controls, N = 5), ESRD 498 +/- 128 (P < 0.02 with respect to controls, N = 3), and ESRD on hemodialysis 438 +/- 85 D (P < 0.02 with respect to controls, N = 5). The mean molecular mass of albumin of all groups was increased significantly with respect to that of fatty acid free albumin (P < 0.001). CONCLUSIONS: Only ESRD was associated with a significant increase in the molecular mass of HSA in vivo. Since this mass increase was very low and much lower than reported for AGE-modified peptides, it may reflect AGE formation on HSA by alpha-oxoaldehydes that accumulate in uremia, rather than modification of albumin by AGE-modified peptides. The molecular mass of HSA in vivo was indicative of a minimal and not a high extent of glycation.

Serum inhibin, activin and follistatin in postmenopausal women with epithelial ovarian carcinoma.

OBJECTIVE: To investigate the role of serum inhibin A, inhibin pro-alphaC immunoreactivity, activin A, and follistatin in postmenopausal women with epithelial ovarian cancer. DESIGN: Case-control study. SAMPLE: e Serum samples from 27 postmenopausal women with epithelial ovarian cancer and 54 controls from the general population participating in an ovarian cancer screening trial. RESULTS: Women with epithelial ovarian cancer had significantly higher serum levels of pro-alphaC immunoreactivity (P = 0.03), activin A (P = 0.004) and follistatin (P = 0.04), but not inhibin A (P = 0.13). Using the 90th centile in the control group as the cut off, pro-alphaC levels were elevated in 41% of women with epithelial ovarian cancer, while inhibin A was elevated in only 15%. Using the 95th centile as the cut off, serum pro-alphaC was elevated in only 11% of women with epithelial ovarian cancer (3/27), while activin A was elevated in 48% (11/23). Follicle stimulating hormone levels were significantly lower in women with epithelial ovarian cancer (P = 0.01). Although, inhibin-related peptides can modulate follicle stimulating hormone levels, there was no correlation between inhibin A, pro-alphaC immunoreactivity, activin A or follistatin and follicle stimulating hormone. CONCLUSION: These data demonstrate that though there is preferential secretion of precursor forms of the alpha subunit rather than dimeric inhibin A by epithelial ovarian cancer, pro-alphaC is unlikely to be a useful tumour marker. Activin A is more commonly elevated in postmenopausal women with epithelial ovarian cancer and its role as a tumour marker in the diagnosis and screening of epithelial ovarian cancer warrants further evaluation.

The pathogenesis and consequences of AGE formation in uraemia and its treatment.

Advanced glycation endproducts (AGEs) accumulate in uraemia as a consequence of diminished clearance of low molecular weight forms which retain their reactivity and may subsequently combine with circulating and tissue macromolecules. Successful renal transplantation is the only form of renal replacement therapy which effectively clears these circulating AGEs; both haemodialysis and peritoneal dialysis are comparatively ineffective although high-flux haemodialysis confers some benefits. De novo AGE formation may be accelerated in uraemia due to carbonyl and oxidative stress leading to further accumulation. The consequences for the patient with chronic renal failure may be acceleration of vascular disease, renal failure progression and dialysis-related amyloidosis. Accelerated peritoneal AGE formation as a consequence of treatment with peritoneal dialysis fluids may be detrimental to peritoneal membrane function but does not appear to contribute to systemic elevation of AGEs.

Release of ouabain-like compound (OLC) from the intact perfused rat adrenal gland.

The present study was designed to investigate the effect of ACTH on release of OLC from the intact isolated rat adrenal, perfused in situ. OLC was measured by EIA. The limit of detection of the assay was 23 pmol/10 minutes. Basal levels of OLC varied from 240 to <23 pmol/10 min. Basal corticosterone levels were generally higher than OLC while aldosterone were generally lower. In 3 of the 5 perfusions the addition of ACTH was followed by rapid increases in both OLC and corticosterone secretion rates within 10 minutes of stimulation. Stimulated levels of OLC were 2 to 4-fold and of corticosterone were 3 to 7-fold those found in basal samples. OLC was found to co-elute with authentic ouabain under isocratic HPLC analysis whilst perfusion medium itself contained no detectable OLC immunoreactivity. These preliminary data suggest that the intact perfused rat adrenal preparation is a useful model for investigating the acute regulation of OLC secretion.

Comparison of in vitro AGE formation between standard PD fluid and a novel bicarbonate/lactate formulation.

Peritoneal advanced glycation end-product (AGE) formation may be accelerated by glucose degradation products produced as a consequence of heat sterilization of peritoneal dialysis (PD) fluid. The formation of these degradation products is reduced if the glucose is separated from the buffers during heat sterilization. This pilot study compared in vitro AGE formation in PD fluid (1.36% and 3.86% glucose) heat sterilized in a two-compartment bag (bicarbonate/lactate buffer) with that in a standard, single-compartment bag (lactate buffer, Dianeal). Peritoneal dialysis fluids were incubated with human serum albumin (HSA, 1 g/L), as a model protein, at 37 degrees C for 0, 5, and 20 days. Formation of AGEs was assessed by measuring fluorescence at each time point. Advanced glycation end-product formation was greater in lactate PD fluid compared with bicarbonate/lactate PD fluid of equivalent glucose strength. Advanced glycation end-product formation in the lactate PD fluid containing 1.36% glucose was comparable to that in the bicarbonate/lactate PD fluid containing 3.86% glucose. The rate of increase in fluorescence per day was greater in the first 5 days of incubation than in the subsequent 15 days. These results are compatible with the presence of greater amounts of glucose-degradation products in the standard single-compartment bag resulting in enhanced AGE formation.