New enzymatic method for determining D-arabinitol in serum

A new reagent has been developed to determine D-arabinitol. This utilizes D-arabinitol 2-oxidoreductase derived from Bacillus sp. with high stability, and water-soluble tetrazolium salt, that can detect NADH with high sensitivity. Since this enzyme does not react to D-mannitol, elimination of D-mannitol is unnecessary. Thus, this is a much simpler process than currently available with commercial kits use D-arabinitol 4-oxidoreductase. The within-run and between-run precisions (CV) were 2.4-6.9% and 3.1-8.7%, respectively, whilst the correlation (r) between the results obtained with our proposed method (y) and those obtained with the commercial "Arabinitec-auto" kit (x) was 0.964 (y = 1.02x + 0.933 mumol/l; n = 69). However, some samples deviated remarkably from correlation in both methods. Our analyzing accuracy is satisfactory in clinical application, as it does not miss positive sample over cut-off value. We are refining this method by investigating why some specimens are apart from correlation significantly.     

Analysis of antibody reactivity for FDP D-dimer fragments by Western blotting

We evaluated three test kits for fibrin degradation products (FDP) D-dimer. We found that six of 217 plasma sample values obtained by Nanopia test were markedly higher than the values obtained using the other two kits. The regression equation for 211 samples (excluding six) was y=0.64x+3.05 (y: Nanopia, x: LIAS AUTO) and the correlation coefficient was 0.915. Therefore, we classified these samples into three categories, namely correlated(y< 1.0x), incompatible (y= 1.0x-2.9x) and markedly incompatible (y> or =3.0x). Selected samples, eight correlated, four incompatible and four markedly incompatible, were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Western blotting(WB). WB analysis using anti-fibrinogen antibody showed that both high molecular weight fragments of cross-linked fibrin (HMW-XDP) and DD/E fragments were present in the correlated samples, but there was less HMW-XDP than DD/E in the incompatible samples and mostly DD/E (HMW-XDP was significantly less than DD/E) in the markedly incompatible samples. These data suggest that plasma FDP samples that contain mostly DD/E and little HMW-XDP demonstrated markedly incompatible values using the three D-dimer test kits. These data was reflected by markedly elevated plasmin alpha2-plasmin inhibitor complex values in the incompatible and markedly incompatible samples. Unfortunately, we did not directly demonstrate these phenomena by WB analysis with two anti-D-dimer antibodies used Nanopia or LPIA reagent. In the near future, we expect that standardization of FDP D-dimer assay will be accomplished.     

Production of the hexitol D-mannitol by Cryptococcus neoformans in vitro and in rabbits with experimental meningitis.

We studied the ability of Cryptococcus neoformans to produce the hexitol D-mannitol in vitro and in rabbits with experimental meningitis. Twelve of twelve human isolates of C. neoformans produced D-mannitol in yeast nitrogen base plus 1% glucose and released D-mannitol into the medium. In a pilot study, pooled cerebrospinal fluid (CSF) from cortisone-treated rabbits given 3 x 10(7) C. neoformans H99 intracisternally contained more D-mannitol (identified by gas chromatography and enzymatically) than CSF from normal controls or cortisone-untreated rabbits with self-limited meningitis. In a second experiment, cortisone-treated rabbits given C. neoformans intracisternally had significantly higher CSF D-mannitol concentrations than controls given cortisone alone at 4, 6, and 8 days after infection. Moreover, log10 CSF D-mannitol correlated well with log10 CSF CFU (r = 0.81) and log10 CSF cryptococcal antigen titers (r = 0.78). Lastly, the initial volume of distribution and elimination half-life of D-mannitol given intracisternally to normal rabbits suggested that D-mannitol was distributed in total CSF and was removed by CSF bulk flow. Thus, C. neoformans produces D-mannitol in vitro and in vivo, and D-mannitol is a quantitative marker for experimental cryptococcal meningitis. D-Mannitol produced by C. neoformans may also contribute to brain edema and interfere with phagocyte killing by scavenging hydroxyl radicals.     

Electrophoresis underestimates the concentration of polyclonal immunoglobulins in serum.

The concentration of gamma-migrating immunoglobulins in blood serum was measured in 200 healthy blood donors by two methods, nephelometry and electrophoresis. Nephelometric values were calculated as IgG + IgM + 1/2 IgA because immunoglobulin G (IgG) and immunoglobulin M (IgM) migrate entirely within the gamma region and immunoglobulin A (IgA) is split between the gamma and beta regions. Electrophoretic values were calculated as % gamma x total protein. Gels were scanned with two different densitometers, providing two sets of electrophoretic data. In each case, the correlation between nephelometry and electrophoresis was very good (r = 0.94 and r = 0.96). However, electrophoresis consistently gave lower results than nephelometry (mean = 2.3 g/L and 4.8 g/L lower, respectively). The disparity between these methods was greater as the concentration of immunoglobulins increased. It is concluded that (1) electrophoresis gives a relative but not absolute value of immunoglobulin concentration in serum; (2) nephelometric and electrophoretic values cannot be used interchangeably; and (3) reference ranges for electrophoresis must take into account the densitometer used.     

Two spent dialysate samples are sufficient for hemodialysis efficacy assessment

INTRODUCTION: The measure of dialysis efficacy is expressed as Kt/V value (calculated from predialysis and postdialysis blood urea concentration). The aim of this study was to assess the possibility of direct calculation of Kt/V value from two spent dialysate samples by using the regular blood-based Kt/V calculation formula with dialysate samples used as surrogates for blood samples, and to detect the most appropriate couple of dialysate samples for Kt/V estimation. PATIENTS AND METHODS: Fifty-two single hemodialysis treatments in 34 anuric patients on chronic bicarbonate low-flux hemodialysis were observed. Kt/V values according to Daugirdas formula from two blood samples and from two dialysate samples were calculated. RESULTS: Kt/V values calculated according to Daugirdas 2 nd generation formula from blood samples (Kt/V sp Daugirdas) were in significant correlation with all Kt/V values obtained from two spent dialysate samples. The highest correlation coefficient (r = 0.74, p < 0.001) and the least standard error of mean of the differences were found between Kt/V sp Daugirdas and value obtained with substitution of urea concentration from dialysate samples taken 60 minutes after dialysis start and at the end of the dialysis into Daugirdas 2 nd generation formula (Kt/V D C D(60) -C D(e) ), which can be expressed as a equation of linear regression y = 0.47 + 0.86x. The highest correlation coefficient (r =0.74, p < 0.001) was found between Kt/V sp Daugirdas values equilibrated according to Daugirdas rate formula, and Kt/V D C D(60) -C D(e) value, which can also be expressed as an equation of linear regression y = 0.43 + 0.73x. CONCLUSION: The results of this study clearly show the sufficiency of only two spent dialysate samples for direct estimation of the Kt/V values, with no blood sample required.     

Determination of elastase 1 in plasma or serum by latex turbidometric immunoassay with automatic analyzer

We developed a latex turbidometric immunoassay(LTIA) for elastase 1. The precisions were 1.0-2.8% intra-run and 1.2-2.9% inter-day. The dilution test showed good linearity between 80-4000 ng/dl. There was interference by bilirubin, hemoglobin, lipemia or rheumatoid factor. Serum and plasma elastase 1 measured by LTIA(y) showed significant correlations with those by RIA(x) (serum: y = 0.98x--18, r = 0.980, n = 64, plasma: y = 0.96x--19, r = 0.976, n = 61). It was confirmed that the values were elevated in patients with pancreatic disease compared to the normal level. These results demonstrate that the determination of elastase 1 in plasma or serum by this method is useful, simple and time-saving, when compared with that by RIA.     

Quantification of bovine IgG in milk using enzyme‐linked immunosorbent assay

A double sandwich enzyme‐linked immunosorbent assay (ELISA) procedure for the quantification of IgG in bovine milk was developed for detecting the concentration of IgG in various homogenized HTST, UHT, evaporated and raw milk samples as well as skim milk powder. ELISA results were consistently lower than radial immunodiffusion (RID) values for the same sample, suggesting interference by an unknown constituent in the milk matrix. This difficulty was overcome by using a reference milk, quantified previously for IgG by RID. A significant linear relationship (y=2.03x‐0.034, r=0.891, n= 150, p<0.001) was obtained for IgG content in unknown raw milk samples determined by ELISA using serial dilutions of the reference milk (y) or commercial IgG (x) to construct standard curves. The slope of the regression line could be used as a correction factor. Alternatively, IgG in unknown samples could be directly quantified from absorbance values of reference milk serial dilutions assayed on the same ELISA plate. Using this procedure, homogenized, HTST pasteurized milk contained from 65 to 79% of the IgG found in raw milk. Skim milk powder also retained a major portion of IgG, while evaporated and UHT pasteurized milk were virtually devoid of IgG.     

Morphometric study of the ductus arteriosus during human development

During prenatal life, the ductus arteriosus connects the left pulmonary artery and the descending aorta. Morphometric features (length, external diameter, volume) of the ductus arteriosus in 131 human fetuses (65 males, 66 females) were studied by means of anatomical, digital and statistical methods. Regression analysis was used to investigate the growth of the ductus arteriosus during gestation. The values of the length of the ductus arteriosus ranged from 3.95 mm for the 15 week gestational group to 12.20 mm for the 34th week of gestation. The length of the ductus arteriosus related to fetal age (x) increased according to the linear function y = -3.0726 + 0.4381x. The mean values of the diameter of the ductus arteriosus ranged from 1.34 to 3.49mm for the 15 and 34 week gestational groups, respectively. The growth of the ductus arteriosus diameter followed in accordance with the linear function y = 0.2072 + 0.0935x. The mean values of the ductus arteriosus volume ranged from 5.08 mm3 for the 15 week group to 117.30 mm3 of the 34 week gestation group. The volume growth increased according to the function y = 0.0007x3.3782. Positive correlation coefficients between arterial parameters and fetal age were statistically significant (P < or = 0.01) and reached the following values: r1 = 0.98 for Length, r2 = 0.90 for diameter and r3 = 0.94 for volume. Despite the increase in absolute diameter, the relative diameter of the ductus arteriosus (ductus arteriosus-to-aortic bulb diameter ratio) decreased from 0.80 to 0.48.     

Homogeneous enzyme immunoassay of acetaminophen in serum

A new commercially available homogeneous enzyme immunoassay, using the glucose-6-phosphate dehydrogenase (G6PDH) catalyzed conversion of NAD to NADH, has been evaluated and applied to the determination of acetaminophen in serum. Replicate analysis of serum control samples over the range of 10-200 micrograms/mL demonstrated a within-assay coefficient of variation of less than or equal to 4.6% and a between-assay coefficient of variation of less than or equal to 5.8%. Regression analysis of two separate groups of 98 and 47 serum samples by this technic, using different reagent lots, and a HPLC reference method gave equations of y = 0.981x - 0.941 (r = 0.984) and y = 1.06x - 2.21 (r = 0.994), respectively. No interference due to hemolysis or turbidity was noted. Evaluation of samples containing 35 commonly prescribed or over the counter medications demonstrated no significant cross-reactivity. Prepared reagents were stable over a period of at least 2 months when stored at 4 degrees C. Correlations between two reagent lots were excellent (r = 0.998). A single sample can be analyzed expeditiously. The result may help evaluate a potential acetaminophen poisoning. Another way to assess this toxicity, calculation of the elimination half-life, has limitations that depend on the precision of the analysis.     

Evaluation of the COBAS amplicor HBV monitor assay and comparison with the ultrasensitive HBV hybrid capture 2 assay for quantification of hepatitis B virus DNA

Performance characteristics of the COBAS Amplicor HBV Monitor test (Roche Diagnostics), which measures hepatitis B virus (HBV) DNA quantitatively, were evaluated and compared with the Ultrasensitive HBV Hybrid Capture 2 (HC2; Digene Corporation) assay. Linearity and within-run precision were assessed for both methods by using eight HBV DNA-positive samples serially diluted to obtain a range of <100 to 500,000 HBV DNA copies/ml and run in triplicate. Agreement between the methods was studied with 100 clinical samples. HC2 assay performance near the limit of detection was investigated through repeat testing of 149 samples with HC2 and testing of 37 samples with HC2 results of <4,700 HBV DNA copies/ml by Amplicor assay and a qualitative PCR assay. The linearity experiment for Amplicor had regression of observed values compared to expected values (y = 1.073x - 0.247; R(2) = 0.993, n = 32; for HC2, y = 0.855x + 0.759, R(2) = 0.729, n = 18). Within-run standard deviation of log HBV DNA copies/ml ranged from 0.003 to 0.348 (Amplicor) and 0.027 to 0.253 (HC2). Agreement assessed by Deming regression was poor [Amplicor = 1.197(HC2) - 0.961; R(2) = 0.799, standard error of the estimate (SEE) = 0.710, n = 94]. Near the lower limit of detection, 32 of 149 repeat HC2 results were <4,700 HBV DNA copies/ml. Of the 37 samples with HC2 results of <4,700 HBV DNA copies/ml, HBV DNA was not detected in 15 samples, while HBV DNA was detected by at least one PCR method in 12 samples. Amplicor is linear from 200 to 200,000 HBV DNA copies/ml with undiluted samples, and this range can be expanded through dilution. Inconsistent HC2 results near the limit of detection justify use of a grey zone.     

Determination of the force necessary for the propagation of tears in ostrich and calf pericardium

The durability of prosthetic heart valve leaflets made of biological materials is limited. A tear in the biomaterial accelerates their early failure, but microtearing of the collagen fibers may be responsible for their medium-term failure. We studied the force necessary to propagate tearing in two biomaterials: ostrich and calf pericardium. One hundred twenty samples of each tissue were tested in an Elmendorf pendulum capable of measuring the force required to tear a tissue in which a predefined slit had been made. The forces required to produce tears, ranging between 2.5 and 0.25 cm in length, were determined. For ostrich pericardium, this force ranged between 67.67 and 4.80 newton, while that required to tear the same lengths of calf pericardium ranged between 70.67 and 4.70 newton. The function that relates the tearing force to the length of the tear was expressed as follows: y = 20.62x + 1.77x(2) (R(2) = 0.923) for ostrich pericardium and y = 45.57x - 7.21x(2) (R(2) = 0.936) for calf pericardium, where y is the force in newton and x is the length in centimeter. Calf pericardium was found to have a greater resistance to tearing. However, these results should be interpreted with caution owing to the fact that the thickness of the majority of the samples of ostrich pericardium was significantly less than that of calf pericardium. A more careful selection and utilization of adult ostrich pericardium would probably improve these results.     

Quantitation of respiratory syncytial virus RNA in nasal aspirates of children by real-time RT-PCR assay

A method was developed for the quantitation of respiratory syncytial virus (RSV) based on real-time RT-PCR using a LightCycler instrument. A control real-time RT-PCR was undertaken on GAPDH mRNA (a human housekeeping gene) was carried out to standardise the non-homogeneous respiratory samples. The real-time RT-PCR method was one log more sensitive for the detection of RSV according to the endpoint dilution technique than the culture method or a conventional qualitative RT-PCR-hybridization-EIA. No cross-reactivity was observed with any of the viruses that could be found in the respiratory tract. RSV and GAPDH were quantified in nasal aspirates from 75 children hospitalised for acute respiratory tract disease: 31 (41.3%) were positive according to the immunofluorescence assay (IFA), 34 (45.3%) were culture-positive and 42 (56%) were positive according to our real-time RT-PCR method. The sensitivity, specificity, positive and negative predictive values of the real-time RT-PCR were 100, 90, 92, 100%, respectively. The samples found to be positive for RSV were classified according to the severity of the disease. The mean number of RSV RNA copies was higher in the severe disease group than in the non-severe group 4.05 x 10(7) vs 9.1 x 10(6) (P=0.055). However, the mean ratio of RSV RNA copies to GAPDH mRNA copies was 42.8 in the severe group, and 22.2 in non-severe group (P=NS).     

Determination of monobromobimane derivatives of phenylmercapturic and benzylmercapturic acids in urine by high-performance liquid chromatography and fluorimetry

A method was developed for the determination in human urine of S-phenylmercapturic (PMA) and S-benzylmercapturic (BMA) acids, metabolites respectively of benzene and toluene. PMA and BMA were determined, after alkaline hydrolysis, to give respectively thiophenol and benzylmercaptan, and coupling of the thiol-containing compounds with monobromobimane (MB), by reversed-phase HPLC on a diphenyl-silica bonded cartridge (100 x 4.6 mm I.D., 5 microm particle size) with fluorimetric detection. Wavelengths for excitation and emission were 375 and 480 nm, respectively. The recovery of PMA and BMA from spiked urines was >90% in the 10-500 microg/l range; the quantification limits were respectively 1 and 0.5 microg/l; day-to-day precision at 42 microg/l was C.V. <7%. The suitability of the proposed procedure for the biological monitoring of exposure to low-level airborne concentrations of benzene and toluene, was evaluated by analyzing the urinary excretion of PMA and BMA in subjects exposed to different sources of aromatic hydrocarbons, namely occupationally-unexposed referents (non-smokers, n=15; moderate smokers, n=8; mean number of cigarettes smoked per-day=17 cig/day) and non-smoker workers occupationally exposed to toluene in maintenance operations of rotogravure machines (non-smokers, n=17). Among referents, non-smokers showed values of PMA ranging from <1 to 4.6 microg/l and BMA from 1.0 to 10.4 microg/l; in smokers, PMA values ranging from 1.2 to 6.7 microg/l and BMA from 9.3 to 39.9 microg/l, were observed. In occupationally exposed non-smoker subjects, BMA median excretion value (23.6 microg/l) was higher than in non-smoker referents (3.5 microg/l) (P<0.001) and individual BMA values (y, microg/l) were associated and increased with airborne toluene concentration (x, mg/m3) according to the equation y=6.5+0.65x (r=0.69, P<0.01, n=17). The proposed analytical method appears to be a sensitive and specific tool for biological monitoring of low-level exposure to benzene and toluene mixtures in occupational and environmental toxicology laboratory.     

Draft proposal to estimate true values of serum potassium in samples from patients with myeloproliferative neoplasma

The pseudohyperkalemia in thrombocytosis is assumed to be due to potassium released from blood cells during blood clotting as reported previously, but its mechanisms remain to be cleared. Although plasma potassium measurements with blood collection tubes containing heparin are performed in many hospitals to avoid pseudohyperkalemia, the burden on patients may come out with further blood sampling by another heparinized tube. Taken together, we investigated laboratory data possibly involved in pseudohyperkalemia in 184 samples from patients with myeloproliferative neoplasma (MPN), and studied estimation capability for true values of serum potassium, driving a correction formula by means of several laboratory data to explain the difference of measured potassium values (K-difference: serum value minus plasma value). Platelet count and mean corpuscular volume (MCV) were adopted as significant variables correlated to K-difference as a result of multiple regression analysis. A correction formula was driven by multiple regression equation with these two variables as follows: y = 0.0006 x 1+0.0004 x 2-0.177 (r= 0.885; x 1, platelet count; x 2, MPV). The correction formula was considered to be useful for estimating the true value of serum potassium in samples from patients with MPN because the corrected serum potassium value correlated highly with plasma potassium value (r = 0.885). These results propose that true values of serum potassium can be estimated by the correction of measured serum potassium values with platelet count and MCV, suggesting that not only quantitative factors but also qualitative factors may be involved in pseudohyperkalemia.     

Enzyme immunoassay for arginine vasopressin (AVP). 2. Serum interference and the measurement of plasma samples

The effect of serum interference on enzyme immunoassay (EIA) for arginine vasopressin (AVP) was studied. Before measurement, plasma was applied on an affinity chromatography to remove AVP and then treated with the acetone-ether method which is usually used for AVP extraction of plasma samples. The AVP-free plasma extract was used to obtain a plasma AVP standard which was compared with various buffer standards of AVP. As a result, the enzyme activities of plasma AVP standard were always lower than those of buffer standards even though the concentration of buffer was increased or added by gelatin. Therefore, EIA for AVP was clinically applicable by using the AVP-free plasma for the standard. Plasma samples were drawn in various clinical conditions and measured for AVP by plasma AVP standard to examine reproducibility and correlation with radioimmunoassay (RIA). The values measured repetitively for the same samples were reproducible. The values measured by EIA correlated well with those measured by RIA (y = 0.67 + 1.13x, r = 0.96). These indicates that EIA for AVP could be applied clinically to measure physiological levels of plasma AVP.     

Significance of high sensitive CRP assay for early detection of newborn babies infection diseases

We have evaluated the accuracy of high sensitive CRP assay method using evanescent wave Immunoassy system(Evanet 20) and significance of this assay on the early detection of infectious diseases in newborn babies. In this assay system, prozone phenomenon was not detected up to 40 mg/dl. The reproducibility of this assay was quite good and the intra run CV value of the same sample was less than 5% for the assay of serum, plasma and whole blood. There was a high correlation between the CRP values in the serum and plasma(r = 0.98, regression formula y = 0.89x + 4.07). Similarly, the values in whole blood and serum samples were quite well correlated(r = 0.98, regression formula y = 0.91x - 6.75). Various humoral elements such as bilirubin, hemoglobin and Chyl did not significantly influence this assay method. A slight increase in blood CRP was clearly demonstrated in the early phase of infectious diseases of newborn babies and monitoring of CRP by this assay system seemed to be quite useful to detect the early phase of infectious diseases in newborn babies. This assay system requires only a small quantity of whole blood to perform quantitative analysis of very small amounts of other substances. Accordingly, this assay system seems to be quite effective for monitoring minute increases in various proteinaceous blood components in emergent laboratory examination or POCT.     

Implementation and quantitative evaluation of analytical methods for attenuation correction in SPECT: a phantom study.

Three differing exact methods of inverting the two-dimensional (2D) exponential Radon transform were implemented and evaluated quantitatively with a phantom study. The phantom had the shape of a pie-chart divided into six cavities, each 480 ml in volume and 10 cm in height, that were symmetrically positioned in a cylinder that was 20 cm in diameter and 10 cm in height. This phantom tests for linearity between true activity concentration and measured activity concentration, and it is denoted as a linearity phantom in the present study. Each cavity contained a different concentration of a homogeneous solution of 99mTc (74, 148, 222, 296, 370 and 444 kBq ml(-1)). Data acquisition was performed with two energy windows: a 20% photopeak energy window set symmetrically over the 140 keV of 99mTc and a secondary 5% energy window set over the 122 keV peak. We optimized a triple-energy window scatter correction method for a gamma camera-collimator system to obtain accurate scatter-corrected projections. A circular ROI 3 cm in diameter was identified over each cavity region, and count density (counts per pixel) was calculated. This value was converted to activity concentration (kBq ml(-1)) using a cross-calibration coefficient between SPECT counts and the gamma well counter. The relation between true activity (x) and measured activity concentration (y) was fitted to a line using the least-squares method. Regression lines were y = 0.63 + 1.0255x (R2 = 0.9987), y = -2.62 + 1.0278x (R2 = 0.9995), and y = 0.092 + 1.0241x (R2 = 0.9989) for the Bellini, Inouye and Metz-Pan methods respectively. In another phantom study using two different types of phantoms, contrast of a cold region in the two was 96% and 101% for all three methods. Combined optimized scatter correction and analytical attenuation correction methods achieve good accuracy in quantification of activity distribution with a uniform attenuating medium.     

Lung transfer for carbon monoxide during the first three years of life

Lung transfer for CO (TLCO) was measured in 35 healthy infants. A steady state, non-invasive method using a technique of alveolar sampling was employed [3]. During the first three years of life, TLCO expressed as mmol.min-1.kPa-1 increased linearly with height (cm): y = 0.036x - 1.15 (r = 0.91); with body weight (kg): y = 0.18x - 0.005 (r = 0.85); with body surface area (m2): y = 3.48x - 0.375 (r = 0.88); and with logn of age (months): y = 0.406x + 0.184 (r = 0.88). FRC was also measured in 29 of these infants by the helium dilution technique. FRC expressed in ml increased linearly with logn of age: y = 62.24x + 62.4 (r = 0.86) and was correlated with TLCO: y = 0.05x + 0.084 (r = 0.8). TLCO and FRC were correlated with the number of alveoli [7, 9]. Thus, in the first three years of life, lung volume and lung gas transfer seem to progressively adapt in order to satisfy energetic needs during growth.     

Comparative performance of the Amplicor HIV-1 Monitor Assay versus NucliSens EasyQ in HIV subtype C-infected patients

In facing global programs for treating HIV-infected patients in the developing countries, there is a real need for viral load assays that are accurate for the local subtypes. The present study was designed to evaluate viral load measurements using the newer version of the NASBA assay in subtype C-infected patients. The performances of this new version, a real-time nucleic acid sequence-based amplification HIV-1 assay (NucliSens EasyQ), were compared to Amplicor HIV-1 Monitor Assay version 1.5 in 79 samples of subtype C-infected patients originating from Ethiopia. Twenty HIV-1 subtype B-infected patients served as a control group. Blood samples from patients in both groups were tested by both assays. The results were compared by a paired, two-tailed Student's t-test. The disparity between the results of the two viral load assays was highly significant in subtype C samples (P = 0.005), such that in the vast majority, higher values of viral load were obtained by the Amplicor assay. However, no differences between the two assays were found in subtype B samples (P = 0.77). CD4 measurements were available for 78 samples of subtype C-infected patients. Of these, a CD4-to-viral load discrepancy (CD4 相似文献   

Evaluation and determination of P-type-alpha amylase activity in human serum by monoclonal antibody

We evaluated a kinetic procedure for determining pancreatic type of alpha-amylase isoenzyme (EC 3.2.1.1.) by using monoclonal salivary amylase antibody in human serum. The principle of this method is to measure residual pancreatic amylase activity after the reaction of monoclonal anti-salivary amylase antibody which is specifically inactivated human salivary amylase. The reaction of antibody with salivary alpha-amylase completed within 2 min of incubation and residual activity of pancreatic amylase was 100%, and the residual salivary amylase activity showed less than 3% of salivary amylase activity after incubation with antibody. The reproducibility and/or precision was 1.2% to 3.4% and the linearity obtained up to 1.500 U/l. Correlation coefficient between the proposed method (y) and electrophoresis (x1) and wheat germ inhibition method (x2) was well, respectively (r = 0.99 with both method, the regression curves was y = 1.02 x1-0.7 and y = 1.04x2-0.7). The reference value from healthy adults (male 98 and female 102) showed 13.6-48.2 U/l according to statistical parametric method and sex difference was not observed. The monoclonal anti-salivary amylase antibody was not cross-reacted with the other animal serum salivary type of amylase.