Using SELDI-TOF mass spectrometry on amniotic fluid and for clinical proteomics and theranostics in disorders of pregnancy

Clinical proteomics encompasses a multitude of experimental approaches, tools, and techniques based on proteomics technology which are directly aimed to accelerate and improve diagnosis and treatment of human diseases. Surface-enhanced laser desorption ionization time-of-flight (SELDI-TOF) mass spectrometry is a variant of matrix-enhanced laser desorption ionization (MALDI) that makes use of chemically-modified surfaces to reduce the complexity of biological samples prior to separation in the mass analyzer. Compared to other proteomic techniques, SELDI has several important advantages such as ability to analyze complex biological samples with minimal pre-processing, ease of handling and high throughput. Importantly, once the biomarker or combination of biomarkers with potential clinical value has been established, validation analyses can be conducted in close proximity to clinical settings which is important for establishing the utility of new diagnostics in clinical decision making and perhaps future theranostic interventions. This chapter provides protocols for experimental design and methodology aimed at (1) discovering biologically relevant biomarkers in amniotic fluid using SELDI-TOF; (2) validating the clinical utility of the biomarkers as new diagnostics; (3) translating the biomarker findings into pathophysiological phenomena to provide further insight and extend the current understanding of the disease process. Many of the principles described herein for amniotic fluid could be generalized to studies involving other types of biological samples and other clinical questions.

[Significance and role of hormone detection methods in the development of endocrinology as a biological discipline]

This review covers the development of technology and methods of hormone detection in the human biological environment: from radioimmunological technique to various immune-enzyme methods. Modem ultrasensitive methods of immuneanalysis, which function on the principle of luminescent or fluorescent signal detection, are described in the article. In the recent years physiochemical ultrasensitive methods of detection using mass-spectrometry in combination with high resolution liquid chromatography are being more acknowledged and in perspective will become the leading technique of biological detection. This article also lists main achievements reached using aforesaid methods of hormone detection both in fundamental and in clinical endocrinology.

[The efficacy of the acute pancreatitis' surgical treatment]

The comparative analysis of blood levels of leukocytes, lymphocytes, the leukocytic intoxication index, amylase, lipase, lactatdehydrogenase and creatinphosphokinase, measured in operated patients with the acute pancreatitis, demonstrated the general positive dynamics of the patients condition. The higher blood levels of the substances in died patients demonstrate the important prognostic value of them. The higher levels of amylase, lipase, lactatdehydrogenase and creatinphosphokinase by the end of the clinical treatment together with the normalization of the rest laboratory data may witness the higher risk of the chronisation of the pancreatitis.

Quantitation of amyloid beta peptides in CSF by surface enhanced MALDI-TOF

Alzheimer's disease is characterized by the deposition of amyloid plaques in the brain. The major components of these plaques are β-amyloid (Aβ) peptides. The CSF concentration of these peptides can therefore provide a valuable biomarker for potentially predicting the state of disease and/or monitoring the efficacy of a drug aiming to inhibit the formation of amyloid plaques. Although the concentration of a given peptide in CSF can easily be measured by ELISA methods, few methods are able to simultaneously observe and distinguish between various peptides of similar yet slightly different amino acid composition. The Surface Enhanced Laser Desorption/Ionization-Time Of Flight mass spectrometry (SELDI-TOF) technology, a platform combining the use of an antibody and MALDI-TOF, can be used to simultaneously detect and quantitate various Aβ peptides with sensitivities in the picomolar range.

The effect of hematocrit on the results of measurements using glucose meters based on different techniques

BACKGROUND

The aim of the study was to evaluate the effect of hematocrit (HCT) on glucose meter assays based on different measurement techniques.

METHODS

This paper studied glucose meters utilizing the glucose dehydrogenase reaction and four measurement techniques: colorimetry (HemoCue), reflectometry (Accu-Chek Active), amperometry (Optium Xido) and coulometry (Optium Omega). The EDTA venous blood samples HCT were modified by adding or removing defined aliquots of plasma. Glucose concentration was measured using each meter in 27 batches of blood samples, with HCT ranging from 20% to 60% in 10% increments. The data were analyzed using repeated measures models and a linear random effects model.

RESULTS

A significant relationship between HCT and glucose reading in all meters was found and, for all meters except Optium Xido, there was a significant modification of this relationship by glucose level. The relative decrease in glucose concentration per 1% increase of the HCT value varied from 0.30% for Optium Omega in samples with glucose concentrations <5.55 mmol/L to 1.37% for Optium Xido in the same stratum (p<0.0001). The 5% glucose meter error (the ADA recommendation) was reached in the <5.55 mmol/L stratum after HCT change by 3.9%-16.7%.

CONCLUSIONS

There is a significant continuous effect of HCT on measurement accuracy of glucose meters across its wide range of values and glucose concentrations. The most sensitive to the HCT interference was the system utilizing amperometric technique (Optium Xido) followed by the one with reflectometric technique (Accu-Chek Active), while the systems with the coulometric technique (Optium Omega) or colorimetric measurements in whole blood haemolysate (HemoCue) were less sensitive.

Magnetic and fluorescent core-shell nanoparticles for ratiometric pH sensing

This paper describes the preparation of nanoparticles composed of a magnetic core surrounded by two successive silica shells embedding two fluorophores, showing uniform nanoparticle size (50-60 nm in diameter) and shape, which allow ratiometric pH measurements in the pH range 5-8. Uncoated iron oxide magnetic nanoparticles (∼10 nm in diameter) were formed by the coprecipitation reaction of ferrous and ferric salts. Then, they were added to a water-in-oil microemulsion where the hydrophilic silica shells were obtained through hydrolysis and condensation of tetraethoxyorthosilicate together with the corresponding silylated dye derivatives-a sulforhodamine was embedded in the inner silica shell and used as the reference dye while a pH-sensitive fluorescein was incorporated in the outer shell as the pH indicator. The magnetic nanoparticles were characterized using vibrating sample magnetometry, dynamic light scattering, transmission electron microscopy, x-ray diffraction and Fourier transform infrared spectroscopy. The relationship between the analytical parameter, that is, the ratio of fluorescence between the sensing and reference dyes versus the pH was adjusted to a sigmoidal fit using a Boltzmann type equation giving an apparent pK(a) value of 6.8. The fluorescence intensity of the reference dye did not change significantly (∼3.0%) on modifying the pH of the nanoparticle dispersion. Finally, the proposed method was statistically validated against a reference procedure using samples of water and physiological buffer with 2% of horse serum, indicating that there are no significant statistical differences at a 95% confidence level.

Kinetic catalytic determination of trace levels of iodide based on the oxidation of basic dyes with hydrogen peroxide monitored potentiometrically using simple PVC electrodes

Four sensitive catalytic potentiometric methods have been developed for trace levels determination of iodide based on its catalytic effects on the oxidation of four dyes: viz. variamine blue (VB), rhodamine B (RB), methylene blue (MB) and malachite green (MG), with H(2)O(2) in H(3)PO(4) medium at 25±0.5°C. The catalyzed reaction rates were estimated potentiometrically by monitoring the potential of the corresponding dye-PVC ion selective electrodes. To select the optimized reaction conditions offering the highest sensitivity of the method, parallel studies were carried out on each dye catalyzed reaction including: the effect of reactant concentration, reaction medium and temperature. The working calibration curves were linear over the concentration range from 0.32 to 2.54 mg L(-1) iodide for VB method and from 3.2 to 12.7 mg L(-1) for other ones. The tolerance limits of more than 20 interfering species were listed indicating the high selectivity of the method. Trace iodide in edible salt and pharmaceutical samples was determined without the need for separation or preconcentration procedures.

Bile acid analysis in various biological samples using ultra performance liquid chromatography/electrospray ionization-mass spectrometry (UPLC/ESI-MS)

In recent years, bile acids (BAs) have received much attention as signaling molecules as well as biosurfactants for lipophilic nutrients. To understand exact BA behavior, the precise distribution of BAs in vivo must be determined. However, to date, it has been difficult to know the precise roles of BA due to variations in BA molecules including conjugated forms. Thus, we reconsidered BA extraction methodology and introduced an ultra performance liquid chromatography/electrospray ionization-mass spectrometry (UPLC/ESI-MS) technique for BA analysis. Consequently, we established a rapid and reliable method, using UPLC/ESI-MS, for the analysis of BAs in various biological samples including liver, bile, blood, intestinal contents, and feces. This method enables us to determine the BA profile, including conjugation status, in a single 30 min run. This technique will be a useful tool for the investigation of the roles of BA metabolism in physiological and pathological conditions.

Confirmation of neonatal screening: reference intervals and evaluation of methodological changes in TSH measurement

Neonatal reference values for serum thyrotropin are scarce and comprise only small numbers of patients. During 2006, changes were made in IMMULITE kits for TSH measurement. To validate methodological changes, 80 serum samples from patients were evaluated and to establish reference intervals, 334 neonates and infants were analyzed (divided into 4 groups). Group 1 (G1) (48-72 h of life) (n=153), group 2A (G2A) (7-10 days of life) (n=65), group 2B (G2B) (11-14 days of life) (n=35), group 3 (G3) (28-40 days of life) (n=81). Current kits overestimate TSH results by 26 to 37%; TSH (mIU/L) reference intervals (percentile 2.5-97.5) were G1 (1.1-12.7), G2A (1.8-9.8), G2B (1.1-7.1) (p < 0.03 vs. G2A), G3 (1.2-6.9). We suggest that during the second week of life, reference values should be divided into an early stage and a late stage, at least, for there to be an adequate interpretation of borderline measurements in newborn thyroid screening.

[Determining the postmortem interval of bone samples: a comparison of luminol chemiluminescence, Hexagon OBTI test, and Combur test]

In the experiment, 16 human bones with known postmortem interval (PMI) that had been buried in soil (0.2 to about 2000 years) were tested in a blind setup with two established methods for determining the PMI (UV fluorescence of the surface of a fresh cut and the luminol chemiluminescence) and with two methods applied for this purpose for the first time (Hexagon OBTI test and Combur test). The results underline the importance of the UV fluorescence and luminol tests in determining the PMI, especially with regard to the question whether the PMI is forensically relevant or not. The results for both new methods, the Combur test strips and the Hexagon OBTI test, which were originally developed for the detection of hemoglobin, were negative for all samples. It remains to be seen if the negative results for these two methods may be due to an inability of hemoglobin or its metabolites to dissolve in the Tris buffer solution used in the experiment.

Exogenous interferences with Jaffe creatinine assays: addition of sodium dodecyl sulfate to reagent eliminates bilirubin and total protein interference with Jaffe methods

BACKGROUND

The study evaluated the impact of interferences on the analytical specificity of three commercial and commonly used creatinine methods (two Jaffe and one enzymatic).

METHODS

Manufacturer creatinine methods plus modified methods were tested with the following interferences: spiking serum with bilirubin, albumin, glucose, hemoglobin and lipid, and patient sera with maximum concentrations of bilirubin, 1,090 micromol/l and protein, 117.8 g/l.

RESULTS

Hemoglobin, 7.5 g/l and lipaemic with triglyceride concentration of 6.27 mmol/l, did not interfere with all assays. Glucose >33.3 mmol/l increased creatinine recovery for Dimension method. Samples spiked with bilirubin imparted a negative bias for Dimension and Architect methods but imparted a positive bias for Vitros assay. However, using patient sera, negative bias with bilirubin was found for all methods, from which Architect method gave the highest effect (R(2)=0.861), followed by Vitros (R(2)=0.239) and Dimension (R(2)=0.163). Protein provided the positive bias for all creatinine measurements that increased with increasing concentration (R(2) ranging from 0.104 to 0.182, P<0.0001). Addition of sodium dodecyl sulfate (SDS) in alkaline-picrate reagent reduced the effect of bilirubin and protein for kinetic Jaffe method. Although adding potassium ferricyanide was well effective for eliminating negative interference of bilirubin, it was prone to interference from protein.

CONCLUSIONS

Endogenous interferences continue to plague creatinine accuracy measurement in both Jaffe and enzymatic methods, and consequentially the estimated glomerular filtration rate. The addition of SDS to the alkaline-pirate reagent was shown to be effective in reducing bilirubin and protein interferences.

Standardization of p‐creatinine assays and use of lean body mass allow improved prediction of calculated glomerular filtration rate in adults: A new equation

OBJECTIVE

To evaluate the Cockcroft-Gault (CG) equation, using various body weight expressions, and the Sawyer equation in predicting glomerular filtration rate (GFR) using an enzymatic and zero-calibrated Jaffe plasma-creatinine assay, and to derive a new robust equation in adults.

MATERIAL AND METHODS

The CG weight measures included total, ideal and adjusted body weight (ABW; lowest of total and ideal) and two lean body mass (LBM) expressions, while the Sawyer equation is based primarily on LBM. Iohexol clearance was used to measure GFR. One derivation set (n = 436; enzymatic assay) was used to evaluate and bias-adjust existing equations when indicated, and to derive a new equation based on plasma-creatinine, age, gender and the body weight measure yielding the best adjusted R2. All equations were then validated in a separate set (n = 414; Jaffe assay).

RESULTS

The existing equations all performed similarly in both sets. Prediction errors of equations based on LBM showed no correlation with BMI. The CGABW and Sawyer equations performed best. The new equation with LBM yielded the highest adjusted R2. In the combined set (n = 850), its accuracy (86 %/98 % of estimates within 30 %/50 % of measured GFR) was significantly better than for the CGABW (79 %/95 %) and Sawyer equations (79 %/93 %) (p<0.001) for each 30 mL/min GFR subgroup within +/-30 % and +/-50 %, except within +/-30 % >120 mL/min. Prediction error did not correlate with BMI, age or gender.

CONCLUSION

A new creatinine-based equation derived in a mainly Caucasian patient sample is a better predictor of GFR than CG-type equations irrespective of the body weight measure used or, if bias-adjusted, when using zero-calibrated creatinine assays.

Bedside analysis of human milk for adjustable nutrition strategy

AIM

Mother's milk is optimum for preterm infants, but human milk fortifier is required at times, because some nutrients are sometimes insufficient for infant growth. It is important to measure the nutrients in breast milk at bedside so that the amount of nutrients that need to be supplemented can be determined. A human milk analyser (HMA, Miris) is currently available. We examined if the macronutrient values measured by human milk analyser are comparable with those measured by conventional methods. We also sought to discover whether we could dilute the milk sample used for the human milk analyser measurement if the amount of milk available for testing was insufficient.

SUBJECTS AND METHODS

First, the results of protein, fat and lactose content in breast milk samples obtained using the human milk analyser and conventional methods were compared. Second, we measured diluted samples and compared the values with nondiluted samples.

RESULTS

When comparing the human milk analyser and conventional methods, all three nutrients exhibited a significantly positive correlation (p < 0.001); lactose content was reliable on the condition that it is 6-7 g/dL. The lactose content measured by the HPLC method was obtained by 3.05 x human milk analyser value - 13.4. When comparing diluted and nondiluted samples, fat and protein had expected values after dilution whereas lactose did not.

CONCLUSION

The human milk analyser can inform us about the amount of major nutrients in breast milk: fat, protein and lactose. However, when human milk is diluted, the lactose content measured by the human milk analyser is overestimated.

[Laboratory input. General practitioners positive about reflective testing]

OBJECTIVE

To investigate the opinion of general practitioners on reflective testing, i.e. the practice of additional tests being performed and comments added to the results by laboratory staff when appropriate.

DESIGN

Descriptive.

METHOD

In the eastern South Limburg region 155 general practitioners received a list of 10 fictitious patient cases, each involving the possible addition of a specific test. The general practitioners could choose what they preferred the laboratory to do: add tests, phone the general practitioner, add a written comment or do nothing. In addition the general practitioners were asked to judge the effect of additional tests and comments on patient management with respect to diagnosis, treatment and referral, using 200 laboratory reports from their own patients.

RESULTS

The response to the fictitious cases was 45%. Most general practitioners favoured the laboratory taking the initiative by adding on tests and commenting on the results in the given clinical scenarios. 78% of the questionnaires accompanying the lab reports were returned by 87% of the general practitioners. In nearly all cases (99%) the service was marked as useful. In more than half of the cases (53%) reflective testing affected the measures taken by the general practitioners.

CONCLUSION

Reflective testing was in general welcomed by the general practitioners. In the majority of cases this led to an improvement in the diagnosis or adjustment of treatment.

Hepatitis C prevalence studied by polymerase chain reaction and serological methods in haemodialysis patients in Mazandaran, Iran

INTRODUCTION

Patients on maintenance haemodialysis are known to have an elevated risk of acquiring hepatitis C virus (HCV) infection. The reported prevalence among haemodialysis patients in the United States ranges from eight percent to ten percent, and is considerably higher in many European and Middle Eastern countries. Therefore, a reliable diagnosis of HCV infection is essential in order to prevent the spread of the disease in dialysis units.

METHODS

All haemodialysis patients were interviewed in two dialysis units in Sari and Ghaemshahr, Iran, in 2006. Blood samples were collected and serum samples screened for anti-HCV antibodies by enzyme-linked immunosorbent assay (ELISA). All samples were retested for confirmation with polymerase chain reaction (PCR).

RESULTS

A total of 186 haemodialysis patients (mean age 58.86 +/- 16.9 years) were studied. Mean duration of haemodialysis was 3.07 +/- 0.3 years. Mean of SGOT and SGPT were 30.64 +/- 6 and 32.01 +/- 8, respectively. Among the 186 patients, 39 (21 percent) were seropositive by ELISA and 21 (11.3 percent) were PCR positive. All PCR positive patients also had positive ELISA. Association between the duration of haemodialysis and HCV seropositivity was statistically significant (p-value is 0.0001), but there was no significant correlation between number of transfusions and HCV seropositivity.

CONCLUSION

Despite the growing demand for cost-effectiveness in the health system, tight control of HCV infection by PCR and ELISA examination must remain an essential part of the routine screening in haemodialysis patients.

[Determination of endogenous anabolic steroids in hair using gas chromatography-tandem mass spectrometry]

A method of gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed for the simultaneous identification and quantification of five endogenous anabolic steroids (testosterone, epitestosterone, androsterone, etiocholanolone, dehydroepiandrosterone) in hair. After alkaline hydrolysis, the hair sample was extracted with diethyl ether, derivatized with a derivatization reagent (N-methyl-N-trimethylsilyl-trifluoroacetamid/iodotrime-thyisilane/DL-dithiothreitol, 1000:5:5, v/v/w) and detected using GC-MS/MS in the multiple-reaction monitoring mode. The one precursor/two product ion transitions for each anabolic steroids were monitored. The limits of detection for five endogenous anabolic steroids were in the range of 0.1 - 0.2 pg/mg. All analytes showed good linearity and the extraction recoveries were 74.6% - 104.5%. The inter-day and intra-day relative standard deviations (RSD) were less than 17.5%. This method has been applied to the analysis of testosterone, epitestosterone, androsterone, etiocholanolone, dehydroepiandrosterone in 80 Chinese hair samples. These data are the suitable references and the basis for the interpretation of the results from endogenous steroids abuse.

Generation of dynamic chemical signals with pulse code modulators

The on-chip generation of dynamic chemical signals in a flow stream via pulse code modulation (PCM) is demonstrated. In this chip the output signal concentration is determined by dispersion and averaging of a serial stream of digitally encoded plugs of concentrated solute and pure solvent as the plugs flow through a long dispersive capillary. A two-bit PCM chemical signal generator was fabricated in two-level PDMS technology. The chip was capable of generating 31 distinct output levels with 10-plug cycles. Several example chemical waveforms (sawtooth and cosine) were generated at flow rates of 43.2 nL s(-1), and plug frequencies of up to 15 Hz, with maximum output signal bandwidth of up to about 1 Hz. The modulator chip was also used to synthesize physiological signals emulating intracellular beta-cell cytosolic Ca(2+) oscillations, extracellular beta-cell insulin release and rat-striatum dopamine release.

[Development of measurement methods and contributions to medical care in the clinical laboratory]

The level of professional interest in clinical chemistry shown by technologists tends to erode as the recent advances in automation of clinical laboratory tests have made it possible to obtain accurate data by simply using reagent kits. Therefore, the most of medical technologists have foolish preconceptions to be impossible for the development of the new measurement methods in the clinical laboratory. However, there should be many studies that medical technologist should perform. In this paper, I give an outline about practice of the chemical reagent development in the laboratory and the effect mainly on the HDL cholesterol (HDL-C) homogeneous method which we developed. Because homogenous methods can easily be performed by automated analyzers, they have been widely implemented not only in Japan, but also throughout the rest of the world. When compared to the precipitation methods requiring centrifugation, homogenous assays are superior because of the great savings in manpower, many more samples can be analyzed within a given time, smaller quantities of samples are required, assay times are shorter, and measurement accuracy is greater. The most important contribution of homogenous assays is that because measurement accuracy is higher, the degree of inter-laboratory differences has been markedly decreased, thus making it possible to establish international standards.