MYC regulates metabolism through vesicular transfer of glycolytic kinases.

Amplification of the proto-oncogene MYCN is a key molecular aberration in high-risk neuroblastoma and predictive of poor outcome in this childhood malignancy. We investigated the role of MYCN in regulating the protein cargo of extracellular vesicles (EVs) secreted by tumour cells that can be internalized by recipient cells with functional consequences. Using a switchable MYCN system coupled to mass spectrometry analysis, we found that MYCN regulates distinct sets of proteins in the EVs secreted by neuroblastoma cells. EVs produced by MYCN-expressing cells or isolated from neuroblastoma patients induced the Warburg effect, proliferation and c-MYC expression in target cells. Mechanistically, we linked the cancer-promoting activity of EVs to the glycolytic kinase pyruvate kinase M2 (PKM2) that was enriched in EVs secreted by MYC-expressing neuroblastoma cells. Importantly, the glycolytic enzymes PKM2 and hexokinase II were detected in the EVs circulating in the bloodstream of neuroblastoma patients, but not in those of non-cancer children. We conclude that MYC-activated cancers might spread oncogenic signals to remote body locations through EVs.

Hexokinase 2 discerns a novel circulating tumor cell population associated with poor prognosis in lung cancer patients.

Unlike other epithelial cancer types, circulating tumor cells (CTCs) are less frequently detected in the peripheral blood of non-small cell lung cancer (NSCLC) patients using epithelial marker-based detection approaches despite the aggressive nature of NSCLC. Here, we demonstrate hexokinase-2 (HK2) as a metabolic function-associated marker for the detection of CTCs. In 59 NSCLC patients bearing cytokeratin-positive (CKpos) primary tumors, HK2 enables resolving cytokeratin-negative (HK2high/CKneg) CTCs as a prevalent population in about half of the peripheral blood samples with positive CTC counts. However, HK2high/CKneg tumor cells are a minority population in pleural effusions and cerebrospinal fluids. Single-cell analysis shows that HK2high/CKneg CTCs exhibit smaller sizes but consistent copy number variation profiles compared with CKpos counterparts. Single-cell transcriptome profiling reveals that CK expression levels of CTCs are independent of their epithelial-to-mesenchymal transition (EMT) status, challenging the long-standing association between CK expression and EMT. HK2high/CKneg CTCs display metastasis and EGFR inhibitor resistance-related molecular signatures and are selectively enriched in patients with EGFRL858R driver oncogene mutation as opposed to EGFR19Del , which is more frequently found in patients with prevalent CKpos CTCs in the blood. Consistently, treatment-naïve patients with a larger number or proportion of HK2high/CKneg CTCs in the blood exhibit poor therapy response and shorter progression-free survival. Collectively, our approach resolves a more complete spectrum of CTCs in NSCLC that can potentially be exploited to identify patient prognosis before therapy.

The pyruvate kinase (PK) to hexokinase enzyme activity ratio and erythrocyte PK protein level in the diagnosis and phenotype of PK deficiency.

Diagnosis of pyruvate kinase deficiency (PKD), the most common cause of hereditary non-spherocytic haemolytic anaemia, remains challenging in routine practice and no biomarkers for clinical severity have been characterised. This prospective study enrolled 41 patients with molecularly confirmed PKD from nine North American centres to evaluate the diagnostic sensitivity of pyruvate kinase (PK) enzyme activity and PK:hexokinase (HK) enzyme activity ratio, and evaluate the erythrocyte PK (PK-R) protein level and erythrocyte metabolites as biomarkers for clinical severity. In this population not transfused for ≥90 days before sampling, the diagnostic sensitivity of the PK enzyme assay was 90% [95% confidence interval (CI) 77-97%], whereas the PK:HK ratio sensitivity was 98% (95% CI 87-100%). There was no correlation between PK enzyme activity and clinical severity. Transfusion requirements correlated with normalised erythrocyte ATP levels (r = 0·527, P = 0·0016) and PK-R protein levels (r = -0·527, P = 0·0028). PK-R protein levels were significantly higher in the never transfused [median (range) 40·1 (9·8-73·9)%] versus ever transfused [median (range) 7·7 (0·4-15·1)%] patients (P = 0·0014). The PK:HK ratio had excellent sensitivity for PK diagnosis, superior to PKLR exon sequencing. Given that the number of PKLR variants and genotype combinations limits prognostication based on molecular findings, PK-R protein level may be a useful prognostic biomarker of disease severity and merits further study.

Biomarker study of the biological parameter and neurotransmitter levels in autistics.

Autism is a prevalent developmental disorder that combines repetitive behaviours, social deficits and language abnormalities. The present study aims to assess the autistic subjects using DSM IV-TR criteria followed with the analysis of neurotransmitters, biochemical parameters, oxidative stress and its ions in two groups of autistic subjects (group I < 12 years; group II ≥ 12 years). Antioxidants show a variation of 10% increase in controls compared to autistic age < 12 years. The concentration of pyruvate kinase and hexokinase is elevated in controls approximately 60% and 45%, respectively, with the significance of 95 and 99%. Autistic subjects showed marked variation in levels of neurotransmitters, oxidative stress and its related ions. Cumulative assessment of parameters related to biochemical markers and neurotransmitters paves the way for autism-based research, although these observations draw interest in an integrated approach for autism.

CircPRKCI relieves lipopolysaccharide-induced HK2 cell injury by upregulating the expression of miR-545 target gene ZEB2.

The aim of this study was to investigate the possible influences of circPRKCI abnormal expression on lipopolysaccharide (LPS)-induced HK2 cell injury and its mechanism. The circPRKCI level was identified in serum samples from patients with urosepsis and healthy subjects, as well as LPS-treated HK2 cells by qRT-PCR. Cell viability, apoptosis, expression of proteins associated with apoptosis, and expression of pro-inflammatory cytokines in LPS-treated HK2 cells were measured. Effects of circPRKCI abnormal expression on LPS-induced HK2 cell injury were then evaluated. Afterward, the binding miRNA of circPRKCI and target gene of miRNA were identified, and the involvements of NF-kB pathway signaling pathway with the effects of circPRKCI were finally studied. CircPRKCI was significantly down-regulated in serum samples from patients with urosepsis and LPS-treated HK2 cells. LPS-induced decrease of cell viability, increase of cell apoptosis, as well as elevated productions of tumor necrosis factor (TNF)-α, interleukins (IL)-1ß, IL-6, and IL-8 in HK2 cells were attenuated by overexpressed circPRKCI. In addition, circPRKCI negatively regulated the expression of miR-545, and miR-545 up-regulation reversed the inhibiting effects of circPRKCI overexpression on LPS-induced HK2 cell injury. Moreover, zinc finger E-box-binding homeobox 2 (ZEB2) was identified as a target gene of miR-545, and ZEB2 overexpression partly reversed the effects of miR-545 up-regulation on LPS-induced HK2 cell injury. Furthermore, NF-kB pathway was revealed to be associated to the effects of circPRKCI on LPS-induced HK2 cell injury. This research indicated that the highly expressed circPRKCI relieved inflammatory injury induced by LPS in HK2 cells by suppressing miR-545/ZEBs and depressing the briskness of NF-kB pathway.

Type 2 diabetes differentially affects the substrate saturation kinetic attributes of erythrocyte hexokinase and phosphofructokinase.

The substrate kinetic parameters of hexokinase (HK) and phosphofructokinase (PFK)-the key irreversible enzymes of glycolysis-in erythrocytes from type 2 diabetic subjects were examined in comparison with control subjects. It was observed that the kinetic parameters such as Km , Vmax , Apparent Kcat , Kcat /Km , and substrate (ATP) inhibition kinetic and substrate binding characteristics are significantly altered in the diabetic group. The observed changes are suggestive of compositional changes in the subunit makeup of HK and PFK. The implication of these findings in relation to energy status of the diabetic erythrocyte and its interrelationship with loss of cell deformability are discussed here.

Antidiabetic and antioxidative properties of the hydro-methanolic extract (60:40) of rhizomes of Curcuma amada roxb. (Zingiberaceae) in streptozotocin-induced diabetic male albino rat: a dose-dependent study through biochemical and genomic approaches.

Background Curcuma amada is the most popular traditional medicine in India for the treatment of diabetes. The present study aimed to focus the antidiabetic and antioxidative activity of C. amada through the analysis of biochemical and genomic levels in a dose-dependent manner in streptozotocin-induced male adult rat. Method Streptozotocin-induced diabetic rats were administered orally with hydro-methanolic extract of C. amada at the dose of 10, 20, 40 and 80 mg/100 g body weight of rats for 28 days. The antidiabetic and antioxidative efficacy of the extract on glycemic, enzymatic, genomic and histological sensors along with toxicity study was investigated. Results The result showed a significant antidiabetic and antioxidative effect of the extract at dose-dependent manner. The significant recovery of fasting blood glucose level, serum insulin, activity of carbohydrate metabolic enzymes and antioxidative enzymes in extract-treated diabetic group as compared to untreated diabetic group were noted. After the extract treatment, the size of pancreatic islet and cell population densities were significantly increased. Activities of glutamate oxaloacetate transaminase and glutamate pyruvate transaminase in liver were significantly recovered along with the correction of Bax and Bcl-2 gene expression in hepatic tissue after the extract treatment in diabetic rats in respect to untreated diabetic group. Out of all the doses, the significant effects were noted at the dose of 20 mg/100 g body weight which has been considered as threshold dose in the concern. Conclusion It may be concluded that the significant and corrective effect in most of the sensors was noted at the minimum dose of 20 mg/100 g body weight of hydro-methanolic extract of C. amada without producing any toxicity.

Altered steady state and activity-dependent de novo protein expression in fragile X syndrome.

Whether fragile X mental retardation protein (FMRP) target mRNAs and neuronal activity contributing to elevated basal neuronal protein synthesis in fragile X syndrome (FXS) is unclear. Our proteomic experiments reveal that the de novo translational profile in FXS model mice is altered at steady state and in response to metabotropic glutamate receptor (mGluR) stimulation, but the proteins expressed differ under these conditions. Several altered proteins, including Hexokinase 1 and Ras, also are expressed in the blood of FXS model mice and pharmacological treatments previously reported to ameliorate phenotypes modify their abundance in blood. In addition, plasma levels of Hexokinase 1 and Ras differ between FXS patients and healthy volunteers. Our data suggest that brain-based de novo proteomics in FXS model mice can be used to find altered expression of proteins in blood that could serve as disease-state biomarkers in individuals with FXS.

An HPLC method for the determination of adenosine diphosphate: An important marker of hexokinase activity in metabolic diseases.

Hexokinases play a critical role in the cellular uptake and utilization of glucose. As such, they are of fundamental importance to all cells. By catalyzing glucose to produce glucose-6-phosphate, hexokinases control the first irreversible step of glucose metabolism and initiate all major pathways of glucose consumption. Our objective was to develop and validate highly sensitive and selective high-performance liquid chromatography with photodiode array detector (HPLC-PDA) assays allowing the determination of adenosine diphosphate, which was used for the determination of hexokinase activity. Samples were analyzed by HPLC-PDA using a C18 analytical column (250 × 4.6 mm) for chromatographic separation. Optimal detection was achieved based on isocratic elution with a mobile phase consisting of a mixture of sodium phosphate monobasic buffer and methanol. This method met all of the requirements of specificity, sensitivity, linearity, precision, accuracy and stability generally accepted in bioanalytical chemistry and was successfully applied to a study of hexokinase activity in an alloxan-induced diabetic rat model. Determination of hexokinase activity will permit characterization of cellular metabolic state in many diseases, such as cancer and diabetes.

Diagnostic performance of PCA3 and hK2 in combination with serum PSA for prostate cancer.

OBJECTIVES: The prostate cancer gene 3 (PCA3), human kallikrein 2, and miRNA-141 are promising prostate cancer (Pca) specific biomarkers. Our aim was to evaluate the detection of PCA3, human glandular kallikrein 2 (hk2), and miRNA-141 mRNA in peripheral blood of patients received prostate biopsy. What's more, we want to detect the value of combination of PSA (prostate specific antigen) in the early diagnosis of PCa. MATERIALS AND METHODS: Hundred patients were divided into 2 groups according to the results of pathologic diagnosis. Quantitative real-time PCR (qRT-PCR) was used to evaluate the mRNA of PCA3, hk2, and miRNA-141 in peripheral blood. At the same time, analyze those clinical outcomes used in the patients. We compared these different outcomes to evaluate the value of new molecular markers. RESULTS: The level of mRNA of PCA3, hK2, and miR-141 in Pca group were significantly higher than that in BPH. PSA had the highest sensitivity in predicting Pca diagnosis (76.7%); PCA3 had the highest specificity (82.5%). And the combination of PCA3, PSA, and hK2 improved area under the curve (AUC)-receiver operating characteristic (ROC) curve largely, especially those with PSA 4-10ng/mL. CONCLUSIONS: PCA3, hK2, and miRNA-141 were biomarkers of Pca with potential clinical application value, especially in patients with PSA gray area. Combining PCA3, PSA, and hK2 performed better than individual biomarkers alone in predicting Pca.

Traceability to a primary reference measurement procedure (ID-LCMS); A key step in validating the clinical accuracy and safety of hospital blood glucose monitoring systems.

OBJECTIVE: A key step in the evaluation of the accuracy of blood glucose monitoring systems (BGMS) is using a comparator method aligned to a high order definitive reference method. We describe how we achieved traceability to an isotope dilution liquid chromatography mass spectrometry (ID-LCMS) method. We used ID-LCMS to evaluate the accuracy and specificity of two hospital BGMS used in China. METHOD: ID-LCMS was used to verify the calibration alignment of the laboratory plasma hexokinase reference method using NIST standard reference material and clinical samples. The ID-LCMS aligned hexokinase method was used to evaluate the clinical accuracy of two BGMS in hospitalized patients. System accuracy was evaluated using Chinese consensus guidelines. BGMS accuracy was also assessed with interference factors known to be present in critically ill patients' blood. RESULTS: The laboratory plasma hexokinase reference method was shown to calibrate closely with ID-LCMS. Two BGMS demonstrated good correlation with this reference method. Only one BGMS met the Chinese guidelines. The interference factors didn't influence this BGMS but adversely affected the clinical accuracy of the other. CONCLUSIONS: We advocate that our IDMS calibration alignment approach for ensuring the accuracy of the glucose reference method should be adopted in evaluations assessing the accuracy of blood glucose monitoring systems.

[THE BIOCHEMICAL AND PATHOPHYSIOLOGICAL MARKERS OF CHEMICAL EFFECT ON ORGANISM, THEIR INFORMATIVENESS AND DIAGNOSTIC SIGNIFICANCE].

The sampling of study included 185 examined workers. Out of them 90 work at "Opitnii zavod Neftekhim" (67 females and 23 males) and 95--at "Kaustik" (64 females and 31 males) from various workshops of the given enterprises. To determine biochemical indicators samples of blood, saliva and urine were collected. The study was carried out in concordance with ethic principles of the Helsinki world medical association declaration, 2008 ed. with receiving written consent of patient to participate in study.

Hypoglycaemic role of wheatgrass and its effect on carbohydrate metabolic enzymes in type II diabetic rats.

Diabetes mellitus (DM) is a leading cause of morbidity and mortality in the world. Insulin resistance and insulin insufficiency is the major factor for the prognosis of type II diabetes. Consistent high glucose level leads to multiple secondary complications in diabetic patients. Hence, hypoglycaemic drugs are of significance for reducing the risk of secondary complications in type II diabetes. Various hypoglycaemic drugs are already available in the market, but they are associated with several side effects. Therefore, traditional herbs have emerged as safer alternative for effective hypoglycaemic treatment. The juvenile grass of common wheat is known as wheatgrass (WG). It is commonly used as a health drink and has potent antioxidant efficacy. It has been used to cure DM in folk medicine. The current study was planned to test the hypoglycaemic effect and pathways regulated by WG on DM. We analysed the glucose and insulin levels in plasma, the activity of glucose oxidative enzymes, hexokinase and glucose 6 phosphate dehydrogenase, in serum and glycogen levels in liver of the male albino Wistar rats. Activity of glucose oxidative enzymes and the levels of insulin and liver glycogen were decreased in rats with diabetes, but they were reversed on treatment with WG. Hence, we conclude that WG can act as a potent anti-hyperglycaemic agent.

Advanced enzymology, expression profile and immune response of Clonorchis sinensis hexokinase show its application potential for prevention and control of clonorchiasis.

BACKGROUND: Approximately 35 million people are infected with Clonorchis sinensis (C. sinensis) globally, of whom 15 million are in China. Glycolytic enzymes are recognized as crucial molecules for trematode survival and have been targeted for vaccine and drug development. Hexokinase of C. sinensis (CsHK), as the first key regulatory enzyme of the glycolytic pathway, was investigated in the current study. PRINCIPAL FINDINGS: There were differences in spatial structure and affinities for hexoses and phosphate donors between CsHK and HKs from humans or rats, the definitive hosts of C. sinensis. Effectors (AMP, PEP, and citrate) and a small molecular inhibitor regulated the enzymatic activity of rCsHK, and various allosteric systems were detected. CsHK was distributed in the worm extensively as well as in liver tissue and serum from C. sinensis infected rats. Furthermore, high-level specific IgG1 and IgG2a were induced in rats by immunization with rCsHK. The enzymatic activity of CsHK was suppressed by the antibody in vitro. Additionally, the survival of C. sinensis was inhibited by the antibody in vivo and in vitro. CONCLUSIONS/SIGNIFICANCE: Due to differences in putative spatial structure and enzymology between CsHK and HK from the host, its extensive distribution in adult worms, and its expression profile as a component of excretory/secretory products, together with its good immunogenicity and immunoreactivity, as a key glycolytic enzyme, CsHK shows potential as a vaccine and as a promising drug target for Clonorchiasis.

[EXPRESSION OF GENES, WHICH CONTROL GLUCOSE METABOLISM, IN BLOOD CELLS OF THE OBESE BOYS WITH INSULIN RESISTANCE].

We studied the expression of genes, which responsible for glucose metabolism, in the blood of obese boys with and without of insulin resistance as well as in normal (control) individuals. It was shown that the expression level of PFKFB3 gene is increased, PFKFB1 and INSIG2--is decreased, but HK2 gene--significantly does not change in the blood cells of obese boys with normal insulin sensitivity as compared to control group. Insulin resistance in obese boys leads to up-regulation of INSIG2 gene expression as well as to down-regulation of PFKFB1, PFKFB3, and HK2 genes in the blood.cells as compared to obese patients with normal insulin sensitivity. Results of this study provide evidence that obesity affects the expression of the subset of glucose metabolism-related genes in the blood cells and that insulin resistance in obesity is associated with changes in the expression level of PFKFB1, PFKFB3, HK2, and INSIG2 genes, which contribute to the development of insulin resistance as well as glucose intolerance.

Hormonal imbalance and disturbances in carbohydrate metabolism associated with chronic feeding of high sucrose low magnesium diet in weanling male wistar rats.

This study was designed to determine chronic effect of high sucrose low magnesium (HSLM) diet in weanling rats on plasma thyroid profile, catecholamines and activities of key hepatic glycolytic, and gluconeogenic enzymes. Compared to control diet fed group, significantly elevated levels of plasma triiodothyronine, tetraiodothyronine, catecholamines (epinephrine, norepinephrine, and dopamine) and activity of hepatic glycolytic (hexokinase and glucokinase), and gluconeogenic (glucose-6-phosphatase) enzymes were observed in high sucrose and low magnesium fed groups. However, HSLM diet had an additive effect on all these three parameters. The study thus, assumes significance as it shows that hormonal imbalance and disorders in carbohydrate metabolism at an early stage of development can be due to dietary modification or due to deficiency of key element magnesium.

The low dose gamma ionising radiation impact upon cooperativity of androgen-specific proteins.

The paper deals with effects of the ionising radiation (γ-IR, 0.5 Gy) upon serum testosterone (T), characteristics of testosterone-binding globulin (TeBG) and androgen receptor (AR) in parallel with observation of androgen (A) responsive enzyme activity - hexokinase (HK). The interdependence or relationships of T-levels with parameters of the proteins that provide androgenic regulation are consequently analyzed in post-IR dynamics. The IR-stress adjustment data reveal expediency of TeBG- and AR-cooperativity measurements for more precise assessments of endocrine A-control at appropriate emergencies.

Factors interfering with the accuracy of five blood glucose meters used in Chinese hospitals.

BACKGROUND: The prevalence of diabetes is increasing in China. Glucose control is very important in diabetic patients. The aim of this study was to compare the accuracy of five glucose meters used in Chinese hospitals with a reference method, in the absence and presence of various factors that may interfere with the meters. METHODS: Within-run precision of the meters was evaluated include Roche Accu-Chek Inform®, Abbott Precision PCx FreeStyle®, Bayer Contour®, J&J LifeScan SureStep Flexx®, and Nova Biomedical StatStrip®. The interference of hematocrit level, maltose, ascorbic acid, acetaminophen, galactose, dopamine, and uric acid were tested in three levels of blood glucose, namely low, medium, and high concentrations. Accuracy (bias) of the meters and analytical interference by various factors were evaluated by comparing results obtained in whole blood specimens with those in plasma samples of the whole blood specimens run on the reference method. Impact of oxygen tension on above five blood glucose meters was detected. RESULTS: Precision was acceptable and slightly different between meters. There were no significant differences in the measurements between the meters and the reference method. The hematocrit level significantly interfered with all meters, except StatStrip. Measurements were affected to varying degrees by different substances at different glucose levels, e.g. acetaminophen and ascorbic acid (Freestyle), maltose and galactose (FreeStyle, Accu-Chek), uric acid (FreeStyle, Bayer Contour), and dopamine (Bayer Contour). CONCLUSIONS: The measurements with the five meters showed a good correlation with the plasma hexokinase reference method, but most were affected by the hematocrit level. Some meters also showed marked interference by other substances.

Improved glycemic control, pancreas protective and hepatoprotective effect by traditional poly-herbal formulation "Qurs Tabasheer" in streptozotocin induced diabetic rats.

BACKGROUND: The present study was undertaken to evaluate the antihyperglycemic, antihyperlipidemic and hepatoprotective effect of a traditional unani formulation "Qurs Tabasheer" in streptozotocin (STZ) induced diabetic wistar rats. Up till now no study was undertaken to appraise the efficacy of "Qurs Tabasheer" in the diabetic rats. Qurs Tabasheer is a unani formulation restraining preparations from five various herbs namely Tukhme Khurfa (Portulaca oleracea seed), Gule Surkh (Rosa damascena flower), Gulnar (Punica granatum flower), Tabasheer (Bambusa arundinasia dried exudate on node), Tukhme Kahu (Lactuca sativa Linn seed). METHODS: Effect of Qurs Tabasheer was assessed in STZ (60 mg/kg, i.p single shot) induced diabetic wistar rats. STZ produced a marked increase in the serum glucose, Total Cholesterol, LDL cholesterol, VLDL Cholesterol, Triglycerides and trim down the HDL level. We have weighed up the effect of Qurs Tabasheer on hepatic activity through estimating levels of various liver enzymes viz. Hexokinase, Glucose-6-Phosphatase and Fructose-1-6-biphosphatase in STZ diabetic wistar rats. RESULTS: In STZ-induced diabetic wistar rats level of Hexokinase, and Glucose-6-Phosphatase was decreased to a significant level while the level of fructose-1-6-biphophatase was augmented. Therapy with Qurs Tabasheer for 28 days to STZ-induced diabetic rats significantly reduces the level of serum glucose, total cholesterol, triglycerides, glucose-6-phosphatase and fructose-1-6-biphosphatase, while magnitude of HDL cholesterol and hexokinase was amplified. CONCLUSION: Antihyperglycemic, antihyperlipidemic activity of Qurs Tabasheer extract in STZ- induced wistar rats was found to be more effective than standard oral hypoglycemic drug Glimepiride.

Impact of prandial status on the comparison of capillary glucose meter and venous plasma glucose measurements in healthy volunteers.

BACKGROUND: There is a negative glucose gradient between the capillary and venous systems, produced by glucose uptake into peripheral tissues. This gradient is augmented by oral glucose ingestion in healthy volunteers; thus prandial status may impact on capillary glucose meter performance. Our primary aim was to investigate whether the (capillary-venous plasma) glucose difference changed in relation to prandial status, in healthy volunteers. METHODS: Glucose was measured fasting and also one hour after an ad libitum breakfast, in 103 healthy volunteers. Duplicate capillary (finger stick) measurements were undertaken at both time points, using both the FreeStyle Lite and AccuChek Performa meters. Simultaneous venous (antecubital fossa) samples were centrifuged immediately after collection and plasma glucose was measured using the laboratory hexokinase method. Results were compared by Bland-Altman difference analysis. RESULTS: The mean (95% CI) pre- and postprandial (capillary-plasma) glucose differences (mmol/L) were calculated for each meter. For the Freestyle Lite, the preprandial difference was -0.51 (-0.58 to -0.45) and postprandial difference was 0.81 (0.69-0.94). Corresponding differences for the Performa were -0.13 (-0.20 to -0.06) and 1.19 (1.07-1.31), respectively. T-test comparison of participants' paired pre- and postprandial (capillary-plasma) glucose differences confirmed a significant meal-related change in glucose estimation for both meters (P < 0.0001). Also, both meters read highest at lower glucose concentrations. CONCLUSIONS: In healthy volunteers, both glucose meters showed a systematic positive bias one hour after breakfast. The significance of this finding in diabetes remains to be determined.