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Dynamic versus static sampling for the quantitative analysis of volatile organic compounds in air with polydimethylsiloxane-carboxen solid-phase microextraction fibers.

Polydimethylsiloxane-Carboxen solid-phase microextraction fibers are now well known to be very efficient trapping media for the analysis of volatile organic compound (VOC) traces in air. However, competitive adsorption, due to the nature of the coating, considerably limits analyte quantitation. In this contribution, different experimental conditions are investigated to achieve quantitative analysis. Static and dynamic sampling were compared for the analysis of 11 VOCs in a standard gaseous mixture at different extraction times (1, 5, 15 and 45 min). The same experiments were performed with four isolated compounds. Adsorption results from gas mixture and isolated compounds were compared and a common linear range (i.e., where quantitative analysis is conceivable) was determined. When sampling was in the dynamic mode, compounds with lower affinity for the coating showed a very narrow linear range, meaning that competition for adsorption was quickly discriminative. The same experiments in static mode allowed one to obtain wider linear ranges for all compounds, especially for lower-affinity compounds: for a 1 min sampling time, acetone showed a linear adsorption range from 3 to 60 microg m(-3) in the dynamic mode which extended from 5 to 300 microg m(-3) in the static mode.

Air↗

Potential of Bacillus cereus for producing an emetic toxin, cereulide, in bakery products: quantitative analysis by chemical and biological methods.

A method for the direct quantitative analysis of cereulide, the emetic toxin of Bacillus cereus, in bakery products was developed. The analysis was based on robotized extraction followed by quantitation of cereulide by liquid chromatography-mass spectrometry and an assay of toxicity by the boar sperm motility inhibition test. The bioassay and the chemical assay gave comparable results, demonstrating that the extracted cereulide was in a biologically active form. Cereulide was formed when cereulide-producing B. cereus strains were present at > or = 10(6) CFU/g in products with water activity values of > 0.953 and pHs of > 5.6. Rice-containing pastries accumulated high contents of cereulide (0.3 to 5.5 microg/g [wet weight]) when stored at nonrefrigeration temperatures (21 to 23 degrees C). Cereulide was not formed in products stored at refrigeration temperatures (4 to 8 degrees C). Cereulide is not inactivated by heating during food processing. Therefore, direct analysis of this toxin in food is preferable to cultivating methods for assessing the risk of food poisoning by emetic B. cereus.

Animals↗

[Immunoglobulins in periapical lesion with special reference to qualitative and quantitative analysis of IgG].

Immunoglobulins in periapical lesions (including 34 radicular cysts and 11 radicular granulomas) were investigated through extracts of the lesions and cystic fluids. The extracts of dental sacs and sera were used as a control. For a qualitative analysis, the immunoglobulins (especially IgG) of each sample were investigated by agarose gel electrophoresis and agarose gel isoelectric focusing. For quantitative analysis, single radial immunodiffusion was employed for determining the concentration of IgG, IgG subclasses, IgA and IgM in the extracts, cystic fluids and autologous sera, also IgE in cystic fluids. In agarose gel electrophoresis, homogeneous bands that were regarded as monoclonal or oligoclonal patterns in gamma region were identified with IgG by immunofixation. These bands were detected in 65% of the radicular cysts, 73% of the radicular cysts obtained cystic fluid, and 73% of the radicular granulomas, but were not detected in any of the autologous sera and dental sacs. In cases that these homogeneous bands were found in extract of cyst, the same bands were found in fluid of same radicular cyst. These results strongly suggested that a part of IgG in periapical lesions was locally produced. By agarose gel isoelectric focusing, immunoglobulins in the extract, cystic fluid and serum were investigated. Many clearly detectable bands were found in extracts of periapical lesions and cystic fluids in the range of pH 6-9 and identified with IgG by immunofixation. These findings revealed restricted heterogeneity of IgG. These IgG bands were found randomly in the range of pH 6-9 and no specific inclination of arrangement. These results suggested that IgG in periapical lesions seem to have different specificities in immunological reaction. Furthermore, in isoelectric focusing pattern of IgG, similar bands were identified in the extract of the cystic wall and fluid of same radicular cyst in 82% of the cases. These bands were detected in some of the dental sacs but not in the serum. Therefore it means that a quantities of IgG in periapical lesions and cystic fluids were locally produced. By quantitative analysis, no statistically significant differences were found in the concentration of IgG, IgG subclasses, IgA and IgM in sera between periapical lesion group and control group.

Immunoglobulin G↗

Quantitative analysis of relative protein contents by Western blotting: comparison of three members of the dystrophin-glycoprotein complex in slow and fast rat skeletal muscle.

We have developed a method for accurate quantitative analysis and statistical comparison of the relative contents of the dystrophin-glycoprotein complex (DGC) in skeletal muscle. This method was applied to compare DGC contents in slow (soleus) and in fast (extensor digitorum longus, EDL) rat skeletal muscles. The quantitative analysis combines a modified bicinchoninic acid (BCA) assay with Western blotting and enhanced chemiluminescence (ECL). This combination allows the use of high levels of detergents and reducing reagents essential for extracting DGC. In addition, the evaluation of the total amount of proteins in each sample makes it possible to have a reference and to accurately compare relative protein levels without using a specific standard. With a large gradient gel, we could concomitantly compare two groups (n = 9) and quantify all protein contents differing highly in their molecular masses (from 35 kDa to 427 kDa). Each experiment was triplicated and normalized; the two muscles were compared using the Mann-Whitney test (P<0.001) to establish their protein content. The DGC relative levels for the slow muscle soleus and the fast muscle EDL differed significantly: dystrophin, beta-dystroglycan, and gamma-sarcoglycan levels were 130%, 110% and 120% higher in the soleus, respectively. The differences observed in the expression level of cytoskeletal associated protein (dystrophin) and transmembranous anchorage components may correspond to a physiological response of the muscle fibers to duration, magnitude, and frequency of the imposed mechanical loading.

Animals↗

Area under pH 4: a more sensitive parameter for the quantitative analysis of esophageal acid exposure in adults.

OBJECTIVE: Traditional quantitative analysis of 24-h esophageal pH monitoring data does not include the pH of reflux episodes. Area under pH 4 (AU4) is a recently introduced parameter that describes the acid exposure rate through both duration and depth of pH falls. METHODS: In Study A, we enrolled 20 healthy controls and 42 patients (18 without esophagitis, 24 with Savary I-III esophagitis) in a study evaluating reference values for 24-h reflux time at pH <4 (RT) and 24-h AU4 by means of receiver operating characteristic (ROC) discriminant analysis. For Study B, we next prospectively applied the resulting cutoffs to 16 healthy controls and to 110 gastroesophageal reflux (GERD) patients (55 with esophagitis) to adjust sensitivity, specificity, and predictive values of both RT and AU4. RESULTS: In Study A, the best cutoff values were 5.1% for RT (Area Index +/- SE, 0.899 +/- 0.038; 95% confidence interval [C.I.], 0.796 +/- 0.961) and 36.1 pH x min for AU4 (Area Index +/- SE, 0.935 +/- 0.03; 95% C.I., 0.842 +/- 0.981); AU4 gave the best performance (p = 0.038 vs RT) in discriminating controls and GERD patients. In Study B, RT was abnormal in three controls and 79 patients; AU4 identified all the controls and patients with abnormal RT and also 10/31 patients (32.3%) with so-called "normal" acid exposure (according to RT). In the whole GERD group of patients, AU4 and RT specificity was 81.2%, whereas sensitivity was 71.8% for RT and 80.9% for AU4 (chi2, 61.831; DF, 1; p < 0.005); PPV/NPV were 96.3%/29.5% for RT, and 96.7%/38.2% for AU4. CONCLUSIONS: AU4 appears to be a simple and sensitive quantitative parameter to measure the esophageal acid exposure in adults submitted to 24-h pH monitoring, and it could be an useful clinical aid in evaluating normal RT tests where, from a clinical point of view, a reflux disease is highly likely.

Adult↗

A new bioassay method for quantitative analysis of tetracyclines.

A new method is described for quantitative analysis of tetracycline, based on the decrease in external pH of bacterial suspensions after the addition of a glucose pulse. The decrease in external pH of these suspensions was inversely proportional to the concentration of tetracycline. The correlation coefficient of standard response lines derived from the bioassay was 0.99. Tetracycline potency was determined in six tetracycline HCl samples by the sugar pulse bioassay and a turbidimetric method. The turbidimetric assay result varied from the glucose-pulse data by no more than 7 and 3% at 3 and 7 min, respectively. The procedure is rapid, precise and quantitative, and requires minimal preparation and use of media, with savings in laboratory resources and time.

Anti-Bacterial Agents↗

Evaluation of a sugar-free medicines campaign in north east England: quantitative analysis of medicines use.

OBJECTIVE: The aim of the study was to evaluate the effectiveness of a sugar-free medicines campaign using suitable prescribing and purchasing indicators. BASIC RESEARCH DESIGN: Quantitative analysis of sugar-free medicine use, before (1995) and after (1996) the campaign. CLINICAL SETTING: Two test and two control districts in north east England. PARTICIPANTS: General medical practitioners (GPs) and community pharmacists. INTERVENTION: A 12-month campaign involving development and distribution of information packs designed to increase the proportion of prescriptions dispensed sugar-free for paediatric use. MAIN OUTCOME MEASURES: Changes in the proportion of the following which were sugar-free: (a) for target prescribed medicines (i) number of prescriptions dispensed. (ii) number of prescribed daily amounts (PDA); (b) for target over the counter (OTC) medicines, (i) number of bottles sold, (ii) number of standard daily amounts (SDA) sold. RESULTS: Quantitative analysis of prescriptions and OTC sales showed statistically highly significant changes towards sugar-free prescribing and dispensing of prescribed medicines but only small increases in the proportion of some sugar-free OTC sales. CONCLUSIONS: The impact of the campaign was shown to be greatest in changing prescribing habits of GPs with less effect on OTC medicine use. The outcome measures used were suitable for quantitative evaluation of the campaign. POST-CAMPAIGN DEVELOPMENT: Sustainable changes in GPs' prescribing behaviour can be facilitated by software suppliers' modifications to computing software used for prescription writing.

Carbohydrates↗

Gamma knife radiosurgery for benign cavernous sinus tumors: quantitative analysis of treatment outcomes.

OBJECTIVE: We review our 8-year experience with gamma knife radiosurgery (GKRS) for the treatment of patients with benign cavernous sinus tumors and present a quantitative analysis of factors relevant to treatment outcomes. METHODS: From 1994 to 2002, a total of 139 patients with benign cavernous sinus tumors were treated in 145 sessions. Their median age was 53 years, and the median follow-up was 3.5 years. The tumors included 57 meningiomas, 76 pituitary tumors (49 nonfunctional adenomas, 15 prolactinomas, 5 adrenocorticotropic hormone-secreting tumors, 6 growth hormone-secreting tumors, and 1 plurihormone-secreting tumor), 4 schwannomas, 1 hemangioma, and 1 paraganglioma. Sekhar tumor grades were as follows: I, n = 28 (20%); II, n = 42 (30%); III, n = 42 (30%); IV, n = 19 (14%); and V, n = 8 (6%). The median tumor volume was 3.4 cm(3), and the median prescribed dose was 15 Gy defined to the 50% isodose line. RESULTS: A total of 136 treated tumors (97.8%) were well controlled by GKRS, with low morbidity. For meningiomas, 29 tumors (51%) were unchanged and 26 (46%) were smaller at a median of 15.2 months. For pituitary tumors, 50 (66%) were unchanged and 25 (33%) were smaller at a median of 20.6 months. Improvement in cranial nerve (CN) function was seen in 19 (36.5%) of 52 patients with pre-GKRS deficits, and 3 patients (2.2%) developed new stable CN deficits after GKRS: 1 patient developed IVth CN palsy at 9 months, and 2 developed persistent VIth CN palsies at 43 and 45 months, respectively, that required surgical correction. Two patients developed transient VIth CN palsies at 48 months that self-resolved after another year. Endocrine function normalized for all 6 treated patients with a growth hormone-secreting tumor at a median of 18 months. One of the 5 adrenocorticotropic hormone-secreting tumors required retreatment after 17 months because of continued cortisol elevation. Thirteen (87%) of 15 prolactinoma patients had normalized prolactin levels within 2 years of the procedure; 2 patients relapsed by endocrine criteria at 18 and 22 months after GKRS. Two patients with normalized prolactin levels completed three normal pregnancies within 3 years of treatment. Six patients (4.3%) with a median tumor volume of 8 cm(3) developed radiation-induced injury at a median of 36 months after GKRS. Five of these patients also underwent external beam radiotherapy and received a median dose of 52.2 Gy in 30 fractions. Quantitative analysis revealed that the radiation dose to critical structures (optic apparatus and pons) is correlated with their distance from tumor margins. Underdosed tumor volume, tumor volume, and total treated volume are correlated with treatment outcomes. CONCLUSION: GKRS is a safe and effective treatment for selected patients with benign cavernous sinus tumors and is an important adjunct for treating postoperative tumor residual and/or recurrent tumor. Continued analysis of treated patients over an extended time is needed to evaluate long-term disease control and potential late GKRS complications.

Adolescent↗

Quantitative analysis of active compounds in pharmaceutical preparations by use of attenuated total-reflection Fourier transform mid-infrared spectrophotometry and the internal standard method.

A new method is presented for the quantitative analysis of compounds in pharmaceutical preparations Fourier transform (FT) mid-infrared (MIR) spectroscopy with an attenuated total reflection (ATR) module. Reduction of the quantity of overlapping absorption bands, by interaction of the compound of interest with an appropriate solvent, and the employment of an internal standard (IS), makes MIR suitable for quantitative analysis. Vigabatrin, as active compound in vigabatrin 100-mg capsules, was used as a model compound for the development of the method. Vigabatrin was extracted from the capsule content with water after addition of a sodium thiosulfate IS solution. The extract was concentrated by volume reduction and applied to the FTMIR-ATR module. Concentrations of unknown samples were calculated from the ratio of the vigabatrin band area (1321-1610 cm(-1)) and the IS band area (883-1215 cm(-1)) using a calibration standard. The ratio of the area of the vigabatrin peak to that of the IS was linear with the concentration in the range of interest (90-110 mg, in twofold; n=2). The accuracy of the method in this range was 99.7-100.5% (n=5) with a variability of 0.4-1.3% (n=5). The comparison of the presented method with an HPLC assay showed similar results; the analysis of five vigabatrin 100-mg capsules resulted in a mean concentration of 102 mg with a variation of 2% with both methods.

Anticonvulsants↗

[Study of post-infarction coronary perfusion using quantitative analysis of myocardial echocardiography with intravenous injection of contrast].

INTRODUCTION AND OBJECTIVES: After a myocardial infarction, damage to the microcirculation indicates a worse prognosis. We compared the usefulness of the quantitative analysis of myocardial contrast echocardiography with intravenous injection of contrast (MCE-iv) with intracoronary injection (MCE-ic) for analyzing coronary perfusion. PATIENTS AND METHOD: We studied 42 patients with a first ST-elevation myocardial infarction, single-vessel disease and a patent artery (TIMI 3, stenosis < 50%). Myocardial perfusion in segments in the infarct-related area was quantified (normalized scale 0-1) with MCE-ic (bolus of Levovist, real-time imaging, perfusion considered normal if > 0.75) and MCE-iv (perfusion of SonoVue, single-image capture in 1 out of each 6 cycles with trigger set at end-systole, perfusion considered normal if > 0.9). Perfusion was considered abnormal if 2 or more segments showed altered perfusion. RESULTS: Quantification with MCE-iv took 5 +/- 1 minutes. No side effects were observed. MCE-ic was normal in 141 segments (80%) out of 176 segments included in the infarcted area, whereas 35 segments (20%) showed abnormal perfusion. MCE-ic was normal in 31 patients (74%) and was altered in 11 cases (26%). Normal perfusion with MCE-iv had a sensitivity of 91%, a specificity of 84% and a kappa index of 0.67 for predicting normal perfusion with MCE-ic (r = 0.86; P < .0001 between the two techniques). CONCLUSIONS: In comparison with MCE-ic, quantitative analysis of single images captured during intravenous perfusion of contrast is an easy, rapid and valid method for analyzing postinfarction coronary perfusion.

Cardiac Catheterization↗

Quantitative analysis of the effect of salt concentration on enzymatic catalysis.

Like pH, salt concentration can have a dramatic effect on enzymatic catalysis. Here, a general equation is derived for the quantitative analysis of salt-rate profiles: k(cat)/K(M) = (k(cat)/K(M))(MAX)/[1+([Na+]/K[Na+])(n')], where (k(cat)/K(M))(MAX) is the physical limit of k(cat)/K(M), K(Na+) is the salt concentration at which k(cat)/K(M) = (k(cat)/K(M))(MAX)/2, and -n' is the slope of the linear region in a plot of log(k(cat)/K(M)) versus log [Na+]. The value of n' is of special utility, as it reflects the contribution of Coulombic interactions to the uniform binding of the bound states. This equation was used to analyze salt effects on catalysis by ribonuclease A (RNase A), which is a cationic enzyme that catalyzes the cleavage of an anionic substrate, RNA, with k(cat)/K(M) values that can exceed 10(9) M(-1) s(-1). Lys7, Arg10, and Lys66 comprise enzymic subsites that are remote from the active site. Replacing Lys7, Arg10, and Lys66 with alanine decreases the charge on the enzyme as well as the value of n'. Likewise, decreasing the number of phosphoryl groups in the substrate decreases the value of n'. Replacing Lys41, a key active-site residue, with arginine creates a catalyst that is limited by the chemical conversion of substrate to product. This change increases the value of n', as expected for a catalyst that is more sensitive to changes in the binding of the chemical transition state. Hence, the quantitative analysis of salt-rate profiles can provide valuable insight into the role of Coulombic interactions in enzymatic catalysis.

Catalysis↗

Quantitative analysis of interstitial alterations in lupus nephritis.

Ninety-eight patients with lupus nephritis followed up for 3 years or more since initial biopsy were the subject of a qualitative and quantitative study of interstitial lesions. Thirty of the 98 patients showed interstitial cell infiltration and/or fibrosis. The initial and final creatinine clearance (Ccr) values were significantly lower in these 30 patients than in the remaining cases. Hypertension and progressive cases were more frequent in the group with interstitial lesions. Histologically, the severity and activity of glomerular lesions and IgG deposition in tubular basement membranes were more severe in the interstitial disease group. On a quantitative analysis of interstitial volumes (IV) in 20 of the 30 patients, there were significant differences in delta IV between the two respective groups with Ccr values greater than 80 ml/min and with those less than 80 both at the initial and final observations (p less than 0.05, each). Further, renal function was significantly lower in 11 cases showing delta IV greater than 17%, than in 9 cases with less than this (p less than 0.01). However, no differences in delta IV were found between the two groups divided according to the degree of severity and activity of glomerular lesions. Further, there was no correlation between renal function, and the severity and activity of glomerular lesions in the 20 cases with interstitial lesions. These results indicate that quantitative analysis is a very useful tool in the evaluation of the functional and prognostic significance of interstitial alterations in lupus nephritis.

Adolescent↗

A program package for quantitative analysis of histologic structure and remodeling dynamics of bone.

Quantitative bone histology has become an increasingly valuable tool for the management and diagnosis of metabolic bone disease. A new computer-assisted method for quantitative analysis of bone histology which combines the advantages of discriminatory input by the investigator with a significant reduction of evaluation time is presented. These programs allow the analysis of a sufficient number of subjects from different populations for the establishment of normative data, and are useful in the diagnosis and documentation of the treatment of metabolic bone disease.

Bone Diseases, Metabolic↗

Chromatography in silica, quantitative analysis of retention mechanisms of benzoic acid derivatives.

A quantitative analysis of the retention of benzoic acid derivatives in reversed-phase liquid chromatography was achieved using a molecular mechanics calculation in the CAChe program. Interaction energy values were calculated for both molecular and ionic forms. The predicted retention factors of partially ionized acids obtained using a combination of dissociation constants well correlated with the values measured by reversed-phase liquid chromatography with pH-controlled eluents. The molecular interaction energy value was calculated by subtracting the energy value of the complex from the sum of energy values of a model-phase and an analyte.

Benzoic Acid↗

Automated, quantitative analysis of interdigestive small intestinal myoelectric activity in rats.

Quantitative analysis of myoelectric activity (EMG), to investigate small intestinal motility in rats, is normally based on manual classification into sequences of phase I, phase II and phase III. This classification is partly subjective. We aimed to develop a more objective method for the analysis of the migrating myoelectric complex (MMC). From the EMG, a derived signal is calculated as a measure of activity. Depending on the level of this derived signal, the EMG is classified into 'quiescent phase', 'irregular phase' or 'activity front'. The threshold levels for these phases are automatically calculated from the EMG data. A proposal for subdivision into MMCs is automatically generated. To calculate MMC length, the user must manually reject nonpropagated activity fronts. While developing the method, more than 19 derived signals were tested. These included variants of spike frequency, signal power and spike-burst length. The spike frequency signal was chosen because it gave minimal deviation from manual classification. Using the new automated method, recordings from the jejunum of 15 healthy rats were analysed (6 h each). The calculated phase lengths were consistent with the results of manual analysis. The presented method allows objective analysis of the interdigestive EMG signals of the small intestine.

Action Potentials↗

Intraoperative brain shift and deformation: a quantitative analysis of cortical displacement in 28 cases.

OBJECTIVE: A quantitative analysis of intraoperative cortical shift and deformation was performed to gain a better understanding of the nature and extent of this problem and the resultant loss of spatial accuracy in surgical procedures coregistered to preoperative imaging studies. METHODS: Three-dimensional feature tracking and two-dimensional image analysis of the cortical surface were used to quantify the observed motion. Data acquisition was facilitated by a ceiling-mounted robotic platform, which provided a number of precision tracking capabilities. The patient's head position and the size and orientation of the craniotomy were recorded at the start of surgery. Error analysis demonstrated that the surface displacement measuring methodology was accurate to 1 to 2 mm. Statistical tests were performed to examine correlations between the amount of displacement and the type of surgery, the nature of the cranial opening, the region of the brain involved, the duration of surgery, and the degree of invasiveness. RESULTS: The results showed that a displacement of an average of 1 cm occurred, with the dominant directional component being associated with gravity. The mean displacement was determined to be independent of the size and orientation of the cranial opening. CONCLUSION: These data suggest that loss of spatial registration with preoperative images is gravity-dominated and of sufficient extent that attention to errors resulting from misregistration during the course of surgery is warranted.

Adult↗

Biochemical studies on 2-deoxy-scyllo-inosose, an early intermediate in the biosynthesis of 2-deoxystreptamine. II. Quantitative analysis of 2-deoxy-scyllo-inosose.

A practical quantitative analysis of 2-deoxy-scyllo-inosose by means of GC-MS selected-ion monitoring (SIM) was exploited in order to assay the enzymatic 2-deoxy-scyllo-inosose formation, the first stage of the 2-deoxystreptamine biosynthesis. Mass spectral fragmentations of 2-deoxy-scyllo-inosose tetra-O-trimethylsilyl (TMS) ether was also investigated by the use of [2,2-2H2]-2-deoxy-scyllo-inosose.

Anti-Bacterial Agents↗

Ionic and non-ionic contrast agent-mediated endothelial injury. Quantitative analysis of cell proliferation during endothelial repair.

PURPOSE: To quantitatively evaluate endothelial injury in vivo and to assess the time course of cellular repair after endothelial cell exposure to ionic and non-ionic contrast media. MATERIAL AND METHODS: Local changes at the cellular level following intraaortic injection of 1 ml of the ionic contrast agent ioxithalamate or 1 ml of the non-ionic contrast agent iomeprol, each with an iodine content of 300 mg/ml, were investigated using rat endothelium as an in vivo model. A sorbitol solution iso-osmolar to iomeprol served as control. Quantitative analysis of endothelial changes by autoradiography of 3H-thymidine-labeled endothelial cells was assessed after 3, 5 and 10 days, determining the 3H-thymidine index and the DNA synthesis rate. RESULTS: Ioxithalamate showed a clear harmful effect on the endothelium, with an elevated 3H-thymidine index of 7.68% on day 3 and 6.89% on day 5, versus 2.97% on day 3 and 2.55% on day 5 for iomeprol and 2.29% on day 3 and 1.91% on day 5 for the control. CONCLUSION: Ionic contrast agents lead to reversible transient focal endothelial cell injury. No such side effect was detectable for non-ionic contrast agents.

Animals↗