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At least 19 recordsLinked to original sources
PubMed1986

Activity concentration and mass concentration (monoclonal antibody immunoenzymometric method) compared for creatine kinase MB isoenzyme in serum.

Results of the "Tandem-E CKMB" immunoenzymometric procedure (y) for creatine kinase (CK; EC 2.9.3.2) were compared with electrophoresis (x) for 160 serum samples from patients suspected of having sustained myocardial infarctions. The results correlated well: y, microgram/L (Tandem assay) = 1.3x-6.3 U/L(electrophoresis) (r = 0.95). CK-MB mass measurement was more stable than enzyme activity after storage and appeared to be more sensitive. Sera from 86 other people, which had no detectable CK-MB upon electrophoresis, gave a mean CK-MB value of 1.1 microgram/L (SD 1.3, range 0-8) with the Tandem assay. To determine whether these low values represented actual isoenzyme, we tested for possible interference by heterophile antibodies in the patients' sera by preincubating the samples with mouse serum before the Tandem assay. The mouse serum did not interfere with the assay of sera that had substantial quantities of CK-MB by electrophoresis. However, in five of six samples that were negative by electrophoresis, the CK-MB values were substantially smaller, indicating that the values measured were false-positives caused by the presence of heterophile antibodies directed against mouse proteins, an interference that could be eliminated by pretreatment with mouse serum.

Antibodies, Monoclonal↗
PubMed1975

The performance of piezoelectric crystal sensors used to determine aerosol mass concentrations.

Aerosol mass concentration determination using piezoelectric crystal sensors was investigated. Five areas of influence were studied: temperature, humidity, particle collection characteristics, response linearity, and mass sensitivity. A theoretical review is included. Neither air stream temperature nor humidity fluctuations were compensated by the use of a reference crystal. The temperature induced error was satisfactorily reduced by minimizing the inlet temperature change rate. The humidity induced error resulted principally from moisture absorption and desorption by the aerosol deposit. The observed linear response limits ranged from 0.2 to 6 mug/mm2 for various aerosols and instrument designs. No relationship between the linearity limit and the point of complete saturation was apparent. The mass sensitivity was a function of the deposit size and location. Energy trapping theory helped to predict the mass sensitivity distribution. The mass sensing ability decreased for particle sizes beginning at approximately 2 mum diameter, reaching essentially zero at 20 mum. The use of viscous crystal coatings appeared to improve the sensing ability in the 2 to 20 mum size range.

Aerosols↗
PubMed2006

Comparison of two methods for obtaining quantitative mass concentrations from aerosol time-of-flight mass spectrometry measurements.

Aerosol time-of-flight mass spectrometry (ATOFMS) measurements provide continuous information on the aerodynamic size and chemical composition of individual particles. In this work, we compare two approaches for converting unscaled ATOFMS measurements into quantitative particle mass concentrations using (1) reference mass concentrations from a co-located micro-orifice uniform deposit impactor (MOUDI) with an accurate estimate of instrument busy time and (2) reference number concentrations from a co-located aerodynamic particle sizer (APS). Aerodynamic-diameter-dependent scaling factors are used for both methods to account for particle transmission efficiencies through the ATOFMS inlet. Scaling with APS data retains the high-resolution characteristics of the ambient aerosol because the scaling functions are specific for each hourly time period and account for a maximum in the ATOFMS transmission efficiency curve for larger-sized particles. Scaled mass concentrations obtained from both methods are compared with co-located PM(2.5) measurements for evaluation purposes. When compared against mass concentrations from a beta attenuation monitor (BAM), the MOUDI-scaled ATOFMS mass concentrations show correlations of 0.79 at Fresno, and the APS-scaled results show correlations of 0.91 at Angiola. Applying composition-dependent density corrections leads to a slope of nearly 1 with 0 intercept between the APS-scaled absolute mass concentration values and BAM mass measurements. This paper provides details on the methodologies used to convert ATOFMS data into continuous, quantitative, and size-resolved mass concentrations that will ultimately be used to provide a quantitative estimate of the number and mass concentrations of particles from different sources.

Journal Article↗
PubMed1996

Development and evaluation of an ELISA method for the determination of lipoprotein lipase mass concentration--comparison with a commercial, one-step enzyme immunoassay.

We developed a non-competitive, enzyme-linked, immunosorbent assay (ELISA) for the quantitation of lipoprotein lipase (LPL) in human postheparin plasma using affinity-purified antihuman milk lipoprotein lipase antibodies produced in chicken eggs and a monoclonal antibody directed against human lipoprotein lipase. We compared our ELISA method with a commercially available sandwich-enzyme immunoassay (Markit-F LPL EIA Kit, Dainippon Pharmaceutical Co, Ltd. Osaka, Japan). The reference values for lipoprotein lipase catalytic activity concentration and mass concentration in healthy Finns were determined. Lipoprotein lipase activity concentration (mean +/- SD) was 297 +/- 112 U/l in women, and mass concentration as measured by the ELISA method was 1058 +/- 367 micrograms/l. The corresponding values for men were 247 +/- 97 U/l and 815 +/- 207 micrograms/l, respectively. Across the whole concentration range of the ELISA method, the control samples' intra- and inter-assay coefficients of variation (CV) were 5.1% and 6.5%, respectively. The correlation between the ELISA and EIA methods was good, r = +0.81. The importance of the correct standardisation of immunoassays is discussed.

Electrophoresis, Polyacrylamide Gel↗
PubMed2005

Fine particle number and mass concentration measurements in urban Indian households.

Fine particle number concentration (D(p)>10 nm, cm(-3)), mass concentrations (approximation of PM(2.5), microg m(-3)) and indoor/outdoor number concentration ratio (I/O) measurements have been conducted for the first time in 11 urban households in India, 2002. The results indicate remarkable high indoor number and mass concentrations and I/O number concentration ratios caused by cooking. Besides cooking stoves that used liquefied petroleum gas (LPG) or kerosene as the main fuel, high indoor concentrations can be explained by poor ventilation systems. Particle number concentrations of more than 300,000 cm(-3) and mass concentrations of more than 1000 microg m(-3) were detected in some cases. When the number and mass concentrations during cooking times were statistically compared, a correlation coefficient r>0.50 was observed in 63% of the households. Some households used other fuels like wood and dung cakes along with the main fuel, but also other living activities influenced the concentrations. In some areas, outdoor combustion processes had a negative impact on indoor air quality. The maximum concentrations observed in most cases were due to indoor combustion sources. Reduction of exposure risk and health effects caused by poor indoor air in urban Indian households is possible by improving indoor ventilation and reducing penetration of outdoor particles.

Aerosols↗
PubMed1999

Mass concentration and elemental composition of PM10 in classrooms.

OBJECTIVES: To investigate the sources of high concentrations of particles of < 10 microns diameter (PM10) in classrooms, observed in a previous study on childhood exposure to PM10, and to study the correlation between classroom and outdoor concentrations of mass and elements of PM10. METHODS: Measurements of PM10 were conducted in two schools and outdoors in Amsterdam, the Netherlands. Averaging time was 24 hours for the outdoor measurements and both 8 hours (school time) and 24 hours for the classroom measurements. Analysis by x ray fluorescence was used to measure the elemental composition of 55 samples from the 11 days when measurements were conducted simultaneously in both classrooms and outdoors. RESULTS: For most elements, classroom concentrations were considerably higher than outdoor concentrations, especially during school hours. The highest classroom/outdoor ratios were found for the elements from soils Si, Ca, and Ti. The only measured elements that were not increased were S, Br, Pb, and Cl, which are dominated by non-crustal sources. For S, Br, and Pb, which are generally associated with particles < 1 micron, significant correlations between classroom and outdoor concentrations and between the two classrooms were found. The other elements generally had low correlations. CONCLUSIONS: The results show that the high PM10 concentrations found in our classrooms are probably due to resuspension of coarse particles or suspension of soil material. Due to these excess coarse particles, the correlation between classroom and outdoor concentrations is lower for elements associated with coarse particles than for elements associated with fine particles. As the general composition of PM10 in classrooms differs from the composition of PM10 in ambient air, the high PM10 mass concentrations in classrooms can probably not be directly compared with ambient air quality guidelines.

Air Pollutants↗
PubMed1994

Contribution of creatine kinase MB mass concentration at admission to early diagnosis of acute myocardial infarction.

OBJECTIVE: To assess the diagnostic value at admission of creatine kinase MB mass concentration, alone or in combination with electrocardiographic changes, in suspected myocardial infarction. DESIGN: Prospective study of all consecutive patients admitted within 12 hours after onset of chest pain to a coronary care unit for evaluation of suspected myocardial infarction. SETTING: Large regional hospital. PATIENTS: In 297 patients creatine kinase and creatine kinase MB activities and creatine kinase MB mass concentration were determined. Myocardial infarction according to the criteria of the World Health Organisation was diagnosed in 154 patients and excluded in 143 patients (including 70 with unstable angina pectoris). RESULTS: Sensitivity/specificity for creatine kinase MB mass concentration in patients admitted within 4 hours and 4-12 hours after onset of chest pain were 45%/94% and 76%/79% respectively. Corresponding values for creatine kinase activity were 20%/89% and 59%/83%, and for creatine kinase MB activity 16%/87% and 53%/87%. Raised creatine kinase MB mass concentration was seen in 17% of patients with unstable angina pectoris. Stepwise logistic regression analysis showed that independent predictors of acute myocardial infarction in patients admitted within 4 hours after onset of chest pain were electrocardiographic changes and creatine kinase MB mass concentration on admission; in patients admitted 4-12 hours after the onset of pain independent predictors were electrocardiographic changes and creatine kinase MB mass concentration and activity. CONCLUSION: Creatine kinase MB mass concentration is a more sensitive marker for myocardial infarction than the activity of creatine kinase and its MB isoenzyme. Electrocardiographic changes on admission in combination with creatine kinase MB mass concentration (instead of creatine kinase and creatine kinase MB activities) are best in diagnosing myocardial infarction.

Aged↗
PubMed1992

Clinical evaluation of a pancreatic lipase mass concentration assay.

An immunoactivation assay for determining pancreatic lipase mass concentration was clinically evaluated and compared with results obtained by measuring total amylase and pancreatic amylase activity. A group of 30 patients with pancreatitis was compared with a control group of 32 patients in which this disease was suspected but excluded. Both lipase mass concentration and pancreatic amylase activity exhibit good sensitivity (0.93 each) and specificity (0.94 and 0.97, respectively) at cutoff concentrations of 200 micrograms/L and 200 U/L, respectively. The median increase in lipase mass concentration (37.1 times the upper limit of the reference interval) in the pancreatitis group was higher than that for either total amylase or pancreatic amylase activity (5.94 and 14.5 times, respectively) but showed a similar time to peak value. We conclude that the lipase assay is the method of choice for diagnosing pancreatitis.

Acute Disease↗
PubMed1996

Cathepsin D serum mass concentrations in patients with hepatocellular carcinoma and/or liver cirrhosis.

Cathepsin D serum mass concentrations were determined by enzyme immunoassay in patients with hepatocellular carcinoma (n = 51) and/or liver cirrhosis (n = 92) or benign steatosis (n = 16) and correlated with some biochemical and clinical properties of these diseases. Increased cathepsin D serum mass concentrations (P < 0.001) were observed in all these groups of patients as compared to normal subjects (n = 98). However, patients with steatosis had serum mass concentrations of this enzyme significantly lower (mean 2-3 fold) than those measured in cancer patients (P < 0.05) or cirrhotic patients (P < 0.001). Interestingly, significantly higher cathepsin D serum mass concentrations (mean + 62%) (P < 0.006) were determined in the cirrhosis group as compared to cancer patients. No correlation between cathepsin D and a number of clinical and biochemical properties examined, namely, alpha-foetoprotein, number of neoplastic lesions and tumour size in cancer patients or, Child-Pugh grade of severity of cirrhosis and other enzymes of liver function tests in the cirrhotic group was found. The present data and those from other studies which indicate that cathepsin D may be involved in carcinogenesis suggest that this enzyme may be potentially useful as an additional biochemical marker to identify cirrhotic patients who may develop precancerous hepatic nodules.

Adult↗
PubMed2001

[Mass concentration and major inorganic compositions of coastal aerosol in Qingdao].

Five times measurements of atmosphere aerosol were conducted from September, 1997 to November, 1998 at a coastal site of Qingdao. The mass concentrations of aerosol and their main soluble compositions were measured. The mass concentration and seasonal variation of the aerosol and its composition were discussed by different size. The PM2.5 (d < 2.5 microns) mass concentration accounts for half of the TSP, while the PM10 (d < 10 microns) mass concentration is about 75% of the TSP. More than 40% of the TSP mass concentration are from that of the soluble ions, among which SO4(2-), NO3- and NH4+ are the primary ones. SO4(2-), NH4+, NO3- are mainly in fine particles which suggest that they mainly existed in secondary aerosols. The mass concentrations of TSP in winter are much higher than those in other seasons.

Aerosols↗
PubMed2006

Relationship between preheparin lipoprotein lipase mass concentration in serum and bare metal stent restenosis.

OBJECTIVES: Insulin resistance or inflammation is known to be related with lipoprotein lipase activity and these factors are also closely associated with the pathogenesis of bare-metal stent restenosis. This study examined the relationship between preheparin lipoprotein lipase protein (preheparin LpL mass) concentration in serum and bare-metal stent restenosis. METHODS: A total of 121 lesions in 112 patients who underwent bare-metal stent implantation using NIR stent or S660/670 stent were examined. Subjects were divided into two groups (N group; patients with normal preheparin LpL mass concentration, n = 50 or L group; patients with low preheparin LpL mass concentration, n = 71) according to the mean levels of preheparin LpL mass concentration (male 39.3 ng/ml, female 50.6 ng/ml). RESULTS: There were no differences in percutaneous coronary intervention or angiographical characteristics. The L group had a significantly higher incidence of restenosis rate and target lesion revascularization than the N group (N group vs L group: 8.0% vs 42.3%, p < 0.0001; 8.0% vs 33.8%, p = 0.0008, respectively). Homeostatic model assessment of insulin resistance as a marker of insulin resistance and high sensitive C-reactive protein concentration were significantly higher in the L group than the N group. Multiple regression analysis showed that only low preheparin LpL mass concentration was an independent factor for restenosis (t value = 3.6, p = 0.0005). CONCLUSIONS: Preheparin LpL mass concentration is closely associated with bare-metal stent restenosis and preheparin LpL mass concentration may be an important marker for the selection of bare-metal stent or drug-eluting stent.

Aged↗
PubMed1993

The mass concentrations of serum troponin T and creatine kinase-MB are elevated before creatine kinase and creatine kinase-MB activities in acute myocardial infarction.

The time-related frequency of elevated results for the mass concentrations of the MB isoenzyme of creatine kinase and of troponin T were compared with that of creatine kinase and creatine kinase-MB activity in patients with acute myocardial infarction. Patients (322; 175 with and 147 without myocardial infarction) consecutively admitted for evaluation of possible acute myocardial infarction were investigated. Reference limits for troponin T (0.1 microgram/l) and creatine kinase-MB mass concentration (5.0 micrograms/l) were exceeded frequently in patients with unstable angina pectoris (troponin T 43%, creatine kinase-MB mass concentration 24%) in contrast to patients with no acute ischaemic heart disease (both < 5%). Within 4 and between 4-8 hours after onset of chest pain, the frequency of elevated results for creatine kinase-MB mass concentration and troponin T in patients with acute myocardial infarction was considerably higher (20-30%) than for creatine kinase and creatine kinase-MB activity. Creatine kinase-MB mass concentration and troponin T both allowed earlier diagnosis of acute myocardial infarction than creatine kinase and creatine kinase-MB activity, but troponin T was not elevated before the creatine kinase-MB mass concentration.

Angina Pectoris↗
PubMed1994

Evaluation of an immunoradiometric assay for bone alkaline phosphatase mass concentration in human sera.

The performance characteristics of an immunoradiometric assay for bone alkaline phosphatase mass concentration in human sera are reported. Within-run imprecision (n = 20) was 12.1% (mean = 7.8 micrograms/l) and 3.6% (mean = 22.8 micrograms/l), between-day imprecision (n = 8) was 10.1% (mean = 20.3 micrograms/l) and 2.8% (mean = 84.3 micrograms/l). There was a linear relationship between the concentrations of the standards employed and the counts per minute up to 120 micrograms/l. The detection limit was 0.3 micrograms/l. In 102 apparently healthy persons (51 males and 51 females; range of age: 18-56 years) the following reference intervals were established: 3.8-21.3 micrograms/l (males) and 3.4-15.0 micrograms/l (females). We compared the values obtained using the immunoassay with those obtained by precipitating of bone alkaline phosphatase with wheat-germ lectin (alkaline phosphatase activity concentration was determined at + 25 degrees C by the optimized standard method according to the Recommendations of the German Society for Clinical Chemistry). For the reference individuals the relationship between the results of the two methods is given by the following regression equation: Bone alkaline phosphatase activity concentration [U/l] = 14.81 + 3.28 x bone alkaline phosphatase mass concentration [micrograms/l] (r = + 0.783). In 89 sera from 32 patients before and after renal transplantation (range of bone alkaline phosphatase mass concentration: 2-39 micrograms/l) comparison between the two methods yielded a linear correlation coefficient of r = + 0.886.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2001

Certification of the mass concentration of creatine kinase isoenzyme 2 (CK-MB) in the reference material BCR 608.

We describe the certification of a mass concentration value in the already prepared creatine kinase-2 reference material (BCR 608). Creatine kinase-2 was purified from human heart. The purified enzyme was diluted in order to measure its protein concentration by the Doetsch method. A protein concentration value of 124.30+/-13.17 mg/l was assigned to the stock solution of purified creatine kinase-2. This stock solution was diluted in 25 mmol/l piperazine-N,N'-bis[2-ethanesulfonic acid] (PIPES) pH 7.2, containing 2 mmol/l ADP, 5 mmol/l 2-mercaptoethanol, 154 mmol/l sodium chloride and 50 g/l human albumin to obtain a stable liquid standard of known creatine kinase-2 mass concentration (80.36 microg/l). This standard was then used to recalculate the creatine kinase-2 mass concentration measured in the BCR 608 material by immunoassay. The mass concentration of creatine kinase-2 in samples of reconstituted BCR 608 was certified to be 93.30+/-9.65 microg/l.

Calibration↗
PubMed1998

Elevated group II phospholipase A2 mass concentration in serum and colonic mucosa in Crohn's disease.

Group II phospholipase A2 has been proposed to play an important role in the pathophysiology of inflammatory bowel diseases. This enzyme has also been linked to host defence mechanisms against bacteria. The current study aimed at measuring the mass concentrations of group II phospholipase A2 in serum and colonic mucosa of patients with Crohn's disease of different severity and of appropriate control patients without any inflammatory disease. The activity of the disease was determined by clinical factors (the simple index score) and endoscopic and histological scoring. The mass concentration of group II phospholipase A2 was measured by a time-resolved fluoroimmunoassay. The mass concentrations of group II phospholipase A2 in serum and colonic mucosa were significantly higher both in patients with active and inactive Crohn's disease when compared with controls. There was statistically significant difference in the mass concentration of group II phospholipase A2 in colonic mucosa but not in serum between inactive and active Crohn's disease. The current results indicate that the mass concentration of group II phospholipase A2 is increased in serum and colonic mucosa of patients with Crohn's disease and that the latter is associated with the degree of the inflammatory activity in the intestinal wall. These results support the idea that group II phospholipase A2 is involved in the local and generalised pathological processes of Crohn's disease.

Adolescent↗
PubMed1994

Creatine kinase-MB mass concentration versus creatine kinase-B activity for the detection of acute myocardial infarction in patients with slightly elevated total creatine kinase activity in serum.

OBJECTIVE: The diagnostic value of creatine kinase-MB mass concentration (CK-MB mass) was compared with that of creatine kinase-B (CK-B) activity in patients with suspected acute myocardial infarction (AMI) but with total serum CK activity only slightly above the reference range. DESIGN: One hundred consecutive blood samples with total CK activity between 120 and 360 U l-1 and CK-B activity > or = 9 U l-1 were analysed. Electrophoresis of CK isoenzymes was also performed. SETTING: Patients from all departments of the hospital were included. About half of the patients originated from the coronary care unit. SUBJECTS: The blood samples derived from 49 patients. Thirteen patients had at least one serum sample with total CK activity above 360 U l-1. These and another three patients were omitted from the study. RESULTS: Acute myocardial infarction had been diagnosed clinically (with CK and CK-B methods) in 12 of 33 patients. However, using the CK-MB mass concentration of the reference method, five of these 12 patients did not have myocardial infarction whereas nine patients with small infarctions were undetected. A good correlation was seen between the results from CK-MB mass concentration and CK isoenzyme electrophoresis, but there was a poor correlation between these methods and CK-B activity including the CK-B/CK ratio. A relatively high proportion (24%) of the selected patients had increased levels of macro CK. CONCLUSION: CK-B activity was inaccurate for the detection of probably myocardial infarction in patients with slightly elevated total CK activity. Increased levels of macro CK interfering with the CK-B assay was one explanation for this observation.

Aged↗
PubMed2002

Estimated effects of composition on secondary organic aerosol mass concentrations.

The composition dependence of secondary organic aerosol (SOA) mass concentrations is explored using an absorptive partitioning model under a variety of simplified atmospheric conditions. A thermodynamic model based on the Wilson equation is used to estimate activity coefficients for mixtures containing primary organics, secondary organics, and water. Changes in the mean molecular weight of the absorbing aerosol mixture due to the presence of water are also accounted for. Model simulations use semivolatile and primary organic components with differing affinities for each other and for water. Results suggest that aerosol composition has an effect on SOA levels that is significant and comparable in magnitude to those due to diurnal temperature variations and semivolatile precursor emission rates. For dissimilar organic components at zero relative humidity, predicted peak SOA mass concentrations are reduced up to 45%. Under low and high relative humidity conditions, SOA levels increase by 3-41% and 11-130%, respectively, depending on the hydrophobicity of the organic components, with maximum concentrations at night when humidity is highest Effects are most pronounced for relatively volatile components that are most sensitive to shifts in the amount and type of absorbing aerosol.

Aerosols↗