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PubMed2004

Development and validation of a method for determination of trace levels of alkylphenols and bisphenol A in atmospheric samples.

A method has been developed and validated in order to assess the occurrence of the alkylphenols tert-octylphenol and the isomers of technical nonylphenol as well as bisphenol A in gasphase and aerosol samples of a remote area. Gasphase samples were adsorbed to XAD2 resin, aerosol samples were taken on glass fiber filters. After ultrasonic extraction, clean-up by column chromatography and silylation of the analytes, ten nonylphenol peaks were quantified separately using a GC-MSD-SIM method. The absolute limits of detection and determination are in the range of a few pg per compound, which is a prerequisite for the quantification of the analytes in relatively unpolluted air. The precision of the whole analytical method is in the range of 1-17% and the recoveries range from 57% to 80%. Problems were encountered during method development due to the tendency of the analytes to sorb to glass surfaces. Silanisation of glassware was crucial to achieve acceptable recoveries. The widespread use of the analytes in plastic resins resulted in sample contamination. For this reason a careful choice of sampling material was necessary. Measured concentrations in gasphase samples (lower nanogram per m3 range) and aerosol samples (upper picogram per m3 range) are one to three orders of magnitude below already published concentrations.

Aerosols↗

PubMed2001

Is compulsory restriction of tar yield of cigarettes a worthwhile public health policy?

BACKGROUND: Although the notion of a "safe cigarette" has proved an illusion, while people continue to smoke, an issue remains of whether compulsory restriction of tar yield is a worthwhile public health policy. METHODS: The study group was comprised of a random population sample of middle-aged Scottish men and women-3464 smokers of cigarettes with known tar yield at baseline. Tar yields were classified into low (< 10 mg), low/middle (10-14.99 mg), and middle or high (> or = 15 mg), according to standard groupings. Deaths within the study cohort were recorded over a period of 13 years. RESULTS: Among low, low/middle, and middle or high tar smokers, 55 (10%), 178 (16%), and 276 (16%), respectively, died. In a comparison group of lifetime never-smokers, 178 (6%) died. After adjustment for daily cigarette dose, duration of smoking, age, gender, social class, type A personality, body mass index, urinary potassium, and antioxidant vitamin consumption, hazard ratios (95% confidence intervals) for all-cause mortality comparing low-tar smokers to low/middle-tar smokers and to middle- or high-tar smokers were 1.64 (1.04-2.58) and 1.46 (0.95-2.26), respectively. Corresponding results for cardiovascular disease were 1.48 (0.74-2.96) and 1.35 (0.79-2.60). For lung cancer, after adjusting for known confounding factors, corresponding hazard ratios were 2.82 (0.98-8.15) and 2.30 (0.81-6.49). CONCLUSIONS: Smoking any type of cigarette is far more risky than abstaining altogether. Although the results obtained comparing tar levels are limited because of lack of repeat measures of smoking during follow-up, potential residual confounding factors, statistical imprecision, and failure to show a dose-response relationship, results do support the hypothesis that persistent smokers will reduce their tobacco-induced health risk if they smoke cigarettes with < 10 mg of tar. However, the data do not permit quantification of the benefits of switching to lower-tar cigarettes. Worldwide legislation to limit tar levels to 10 mg as an absolute maximum is recommended, while recognizing that this must be part of an integrated approach to tobacco control.

Adult↗

PubMed2003

Determination of ximelagatran, an oral direct thrombin inhibitor, its active metabolite melagatran, and the intermediate metabolites, in biological samples by liquid chromatography-mass spectrometry.

Analytical methods for the determination of ximelagatran, an oral direct thrombin inhibitor, its active metabolite melagatran, and intermediate metabolites, melagatran hydroxyamidine and melagatran ethyl ester, in biological samples by liquid chromatography (LC) positive electrospray ionization mass spectrometry (MS) using selected reaction monitoring are described. Isolation from human plasma was achieved by solid-phase extraction on octylsilica. Analytes and isotope-labelled internal standards were separated by LC utilising a C(18) analytical column and a mobile phase comprising acetonitrile-4 mmol/l ammonium acetate (35:65, v/v) containing 0.1% formic acid, at a flow-rate of 0.75 ml/min. Absolute recovery was approximately 80% for ximelagatran, approximately 60% for melagatran ethyl ester and >90% for melagatran and melagatran hydroxyamidine. Limit of quantification was 10 nmol/l, with a relative standard deviation <20% for each analyte and <5% above 100 nmol/l. Procedures for determination of these analytes in human urine and breast milk, plus whole blood from rat and mouse are also described.

Animals↗

PubMed1989

Effects of DL-2-amino-5-phosphonovalerate on metabolism of catecholamines in synaptosomes from rat brain.

Incubation of synaptosomes from rat brain with DL-2-amino-5-phosphonovalerate (APV) stimulated an increased release of dopamine, and this effect was strictly dependent on the extrasynaptosomal calcium level. APV increased biosynthesis of dopamine from tyrosine by 30%, whereas monoamine oxidase activity was inhibited by 30%. When synaptosomes were incubated with radioactive dopamine, APV caused a large decrease in incorporation of label into 3,4-dihydroxyphenylacetic acid but greatly increased incorporation into norepinephrine and its N-methyl derivatives. Quantification of dopamine and its metabolites in synaptosomes, using electrochemical detection, indicated that the presence of APV resulted in changes in the absolute levels of the aforementioned dopamine metabolites similar to the changes in radiolabel incorporation. Omission of Ca2+ from the extrasynaptosomal medium greatly diminished the APV-induced changes in catecholamine metabolism. The metabolic changes appear to largely result from an increased intrasynaptosomal Ca2+ level due to the APV-induced increase in calcium permeability of the plasma membrane.

2-Amino-5-phosphonovalerate↗

PubMed1986

Changes in buccal white spots during 2-year consumption of dietary sucrose or xylitol.

The purpose of the present study was to quantitate changes in buccal white-spot lesions during sucrose and xylitol consumption. Standardized color macrophotographs of white-spot lesions were taken 7 months after the beginning and at the end of the 2-year study. The quantification was based on the planimetry of these photographs. The area of white-spot lesions decreased in the xylitol group in absolute values (p less than 0.01) and in percentages (p less than 0.001). In the sucrose group the area of white-spot lesions increased in absolute values (p less than 0.05) and in percentages (p less than 0.01) during the 17-month observation period. The stereomicroscopic evaluation gave a similar result; the ordinally quantified caries scores (CIS) increased in the sucrose group and decreased in the xylitol group, and the difference between the groups was highly significant (p less than 0.001). Thus the present findings showed that xylitol consumption caused remineralization of incipient white-spot lesions on buccal surfaces.

Dental Caries↗

PubMedDate not supplied

Increased energy needs in patients with quadriplegia and pressure ulcers.

Health individuals with quadriplegia generally have a reduced metabolic rate. However, individuals with quadriplegia who develop pressure ulcers may have an elevated metabolic rate. In this study, energy expenditure in 16 individuals with quadriplegia and pressure ulcers (PU-QUAD) was compared to the energy expenditure in 16 individuals with quadriplegia but no pressure ulcers (NPU-QUAD) and 16 healthy non-spinal cord injured subjects (controls). Resting energy expenditure (REE) was measured by indirect calorimetry. Both measured REE (t(30) = 2.38, p = 0.24) and percent predicted REE (t(30) = 3.23, p = .003) were significantly higher in subjects with quadriplegia and pressure ulcers compared with subjects with quadriplegia but no pressure ulcers. On average, REE in the PU-QUAD subjects was nearly equal to the absolute energy expenditure of healthy non-spinal cord injured controls. To ensure optimal care of patients with quadriplegia and pressure ulcers, quantification of energy expenditure with provision of adequate caloric intake is recommended.

Adult↗

PubMedDate not supplied

[Quantification of serum interference in immune complex phagocytosis in seronegative spondylarthropaties, systemic lupus erythematosus, and rheumatoid disease].

Pathological samples (55) of serum selected from patients with Seronegative Spondylarthropathies, Systemic Lupus Erythematosus and Rheumatoid Disease were studied. The serum of all these patients showed negative rheumatoid factor by latex fixation reaction. The determination of the interference on the phagocytosis of gamma globulin aggregated by guinea pig's macrophages was obtained by one formula. The serum characterization was determined by selecting the ones that presented the most expressive results in the phagocytosis interference, by facilitation or inhibition. The results, in absolute and percentage values, showed the predominance of the interference phenomenon in phagocytosis, with significant statistical values (p < 0.05), when compared with normal serum. The comparative analysis among the diseases studied in the quantification of the serum interference in the phagocytosis of the immunocomplexes has not showed any significant difference. The phagocytosis inhibition occurred with more preponderance in the serum of patients with Reiter's Syndrome and Psoriatic Arthritis; in serum patients with Reiter's Syndrome there was a statistically significant difference in the inhibition of the phagocytosis (p = 0.0247). The serum characterization did not show that the serum fraction was responsible for the phagocytosis interference. In this stage it has been verified that there has not been an uniformity in the graphic curve of dilutions studied. The possibility of the existence of more than one element with interference in the phagocytosis of the studied immunocomplexes was mentioned.

Adolescent↗

PubMed1998

Quantification of tissue eosinophils and lymphocytes in histologic sections.

During a study of eosinophil-predominant gallbladder disease, an image analysis (IA) technique was developed for quantification of eosinophils and lymphocytes in routine formalin-fixed tissue sections. Alternating sections were stained with hematoxylin and eosin for eosinophils and with monoclonal CD45 antibody visualized with diaminobenzidine by an avidin-biotin procedure for lymphocytes. A protocol was then developed using a commercially available image analyzer and two well-defined macro routines. The system was validated with cell block sections prepared from peripheral blood samples with known eosinophil and lymphocyte counts. The eosinophil counts obtained by this IA technique showed excellent correlation with the absolute counts from a peripheral blood analyzer (r2 = 0.987). The lymphocyte counts obtained by IA showed good correlation with the absolute counts (r2 = 0.820). This IA-based technique provides a sensitive, reproducible, and substantiated means of quantifying inflammatory cells in tissue sections. This rapid and easily learned technique adds quantification as a complementary dimension to the subjective assessment of tissue morphology.

Eosinophils↗

PubMed1987

Identification and quantification of subsets of mononuclear inflammatory cells in melanocytic and other human tumors.

We used monoclonal antibodies and an indirect immunoperoxidase technique to identify mononuclear inflammatory cells associated with human tumors. The absolute number of the different types of inflammatory cells was assessed by using a point-counting technique. We studied tissues from six primary cutaneous melanomas, six metastatic melanomas, eight melanocytic nevi, 14 breast cancers, seven examples of fibrocystic disease of the breast, 11 lung cancers, and six colon cancers. Virtually all tumors were associated with substantial numbers of T lymphocytes (Leu3a-positive T helper-inducer cells predominating) and macrophages. Primary melanomas contained significantly more T lymphocytes (P less than .002), macrophages (P less than .005), and Langerhans/dendritic cells (P less than .002) than nevi or normal skin and had a higher proportion of T cells than metastatic melanomas (P less than .01). Breast cancers contained more T lymphocytes and macrophages than occur with fibrocystic disease (P less than .0001 and P less than .002, respectively) and more B lymphocytes. Cancers of the lung and colon contained moderate numbers of T lymphocytes and macrophages; however, colon cancers contained a higher proportion of B cells. Leu7-positive NK/K cells were noted in small numbers in all tumors examined.

Female↗

PubMed1995

Pharmacokinetic development of quinolone antibiotics.

A prerequisite for the pharmacokinetic development of quinolone antibiotics is a sensitive and accurate method for the quantification of the drug in biological fluids. Both, a drug specific (e.g. HPLC) and a drug non-specific but effect related assay (e.g. bioassay) should be used during early clinical development to detect major active metabolites. The basic pharmacokinetic behavior of the drug is investigated as part of the early phase I program, where single and multiple ascending dose studies are performed to characterize the safety and tolerability of the quinolone in healthy volunteers. Further pharmacokinetic studies are performed to describe the absolute bioavailability, dose proportionality, pharmacokinetics in young and elderly, male and female volunteers. The suitability of the clinical dosage from must be evaluated in comparison to an oral solution and by quantification of the effect of food on bioavailability. The characterization of the absorption in different parts of the gastrointestinal tract may be valuable for dosage form optimization. In order to start phase IIb clinical trials, the potential of possible drug-drug interactions with antacids, cimetidine, theophylline and warfarin has to be evaluated. This can be done by in vitro and in vivo preclinical experiments, before formal clinical-pharmacology studies are performed. Further pharmacokinetic characterization (e.g. studies in special subpopulation, extended interaction studies, total recovery using 14C-labelled compound, blister fluid penetration) will be done parallel to the phase II/III development program. During these efficacy and safety trials blood samples should be obtained and PK-parameters can be calculated using sparse data analysis methods like non-linear mixed effect modeling (NONMEM) or Bayesian methods to characterize the pharmacokinetics in the target population.

4-Quinolones↗

PubMed1999

A deterministic approach to automated stenosis quantification.

We developed a new approach to quantitative coronary angiography (QCA), which overcomes several limitations of available programs, such as dependence on operator input; limited tracking ability; fixed correction of the point spread function (PSF); and different calibration on empty vs. contrast-filled catheters. The program (Intelligent Images QCA, version 1.4) provides absolute reproducibility by deterministic, operator-independent identification of the skeleton and the edges of the coronary tree. The algorithm works as follows: application of a matched filter to emphasize selectively the coronary arteries; adaptive threshold binarization; binary thinning and skeletonization; perpendicular resampling with sub-pixel interpolation; derivative filtering; minimal cost edge detection; and automatic identification and quantification of the stenosis. Operator's interaction is restricted to definition of a region of interest; editing of either skeleton or edges is not allowed. PSF correction is fine-tuned to the actual frequency response of the imaging chain by calibration on a contrast-filled conical lucite phantom. Catheter calibration is carried out by a second derivative-based edge detection much less sensitive to the presence of contrast. In vitro phantom analysis (0. 5 to 5.0 mm) showed accuracy of 0.028-0.031 mm and precision of 0. 054-0.062 mm on nonmagnified images from the angio TV chain and the cine projector, respectively. In vivo evaluation on a series of consecutive diagnostic angiograms yielded correct contour detection of 70/73 stenoses (96%); interobserver intraframe MLD variability 0. 00 mm; correct tracking of catheter edges 100%; interobserver variation coefficient of catheter calibration 3.3%; and mean difference of calibration factor on contrast-filled vs. empty catheters 2.7%. This new approach significantly improves reproducibility with respect to conventional QCA, maintaining high accuracy, precision, and applicability. Cathet. Cardiovasc. Intervent. 48:435-445, 1999.

Algorithms↗

PubMed2006

Atmospheric pressure desorption/ionization on silicon ion trap mass spectrometry applied to the quantitation of midazolam in rat plasma and determination of midazolam 1'-hydroxylation kinetics in human liver microsomes.

The application of atmospheric pressure desorption/ionization on silicon (AP-DIOS) coupled with ion trap mass spectrometry (ITMS) was investigated for the quantification of midazolam in rat plasma, and determination of midazolam 1'-hydroxylation kinetics in pooled human liver microsomes. Results indicate good sensitivity with absolute detection limits for midazolam in rat plasma of approximately 300 femtograms. A linear dynamic range from approximately 10-5000 ng/mL was obtained in rat plasma with analysis times of 1 min per sample. Kinetic constants for midazolam 1'-hydroxylation in human liver microsomes yielded an apparent Km of 10.0 microM and Vmax of 6.4 nmol/min/mg. Studies investigating the inhibition of 1'-hydroxymidazolam formation by the cytochrome P450 3A4 model inhibitor ketoconazole yielded an IC50 of 0.03 microM. Quantitative precision for replicate analysis of rat plasma and human liver microsomal samples was variable with relative standard deviation (RSD) values ranging from a low of approximately 3% to over 50%, with the highest variability observed in data from human liver microsomal incubations. While preliminary studies investigating the application of AP-DIOS-ITMS suggested feasibility of this technique to typical pharmacokinetic applications, further work is required to understand the underlying causes for the high variability observed in these investigations.

Animals↗

PubMed1991

Neurocatin induces changes in release and level of serotonin in synaptosomal fraction from rat brain.

A newly isolated factor from mammalian brain, neurocatin, is shown to increase both the level and release of serotonin in suspensions of synaptosomes isolated from rat brain. Incubation of synaptosomes for 10 min with approximately 20 nM neurocatin resulted in release of about 50% of the total pool of serotonin. Quantification of serotonin and its major metabolite, using an electrochemical detector, indicated that the presence of neurocatin also caused an increase in the absolute level of serotonin and decrease in its catabolism to 5-hydroxyindoleacetic acid (5-HIAA). The effect is dependent on the time of incubation and concentration of neurocatin. At a concentration of 20 nM, neurocatin increased about 60% the level of serotonin and decreased about 50% the level of 5-HIAA. Depolarization conditions--50 microM veratridine and 50 mM K+ medium--increased release of serotonin by 50% and 30% respectively without affecting the level of serotonin or its catabolism to 5-HIAA.

Animals↗

PubMed2005

Selective quantitative bioanalysis of proteins in biological fluids by on-line immunoaffinity chromatography-protein digestion-liquid chromatography-mass spectrometry.

A quantitative method for the determination of proteins in complex biological matrices has been developed based on the selectivity of antibodies for sample purification followed by proteolytic digestion and quantitative mass spectrometry. An immunosorbent of polyclonal anti-bovine serum albumin (BSA) antibodies immobilized on CNBR agarose is used in the on-line mode for selective sample pretreatment. Next, the purified sample is trypsin digested to obtain protein specific peptide markers. Subsequent analysis of the peptide mixture using a desalination procedure and a separation step coupled, on-line to an ion-trap mass spectrometer, reveals that this method enables selective determination of proteins in biological matrices like diluted human plasma. This approach enhances substantially the selectivity compared to common quantitative analysis executed with immunoassays and colorimetry, fluorimetry or luminescence detection. Hyphenation of the immunoaffinity chromatography with on-line digestion and chromatography-mass spectrometry is performed and a completely on-line quantification of the model protein BSA in bovine and human urine was established. A detection limit of 170 nmol/l and a quantification limit of 280 nmol/l is obtained using 50 microl of either standard or spiked biological matrix. The model system allows fully automated absolute quantitative mass spectrometric analysis of intact proteins in biological matrices without time-consuming labeling procedures.

Animals↗

PubMed2001

Brain SPECT with 123I-IMP for the early diagnosis of Creutzfeldt-Jakob disease.

We performed brain CT and single-photon emission computed tomography (SPECT) using N-isopropyl-p-[123I] iodoamphetamine (123I-IMP) as a tracer in the early stage of seven patients with Creutzfeldt-Jakob disease (CJD). In four of the patients, we determined absolute values of regional cerebral blood flow (rCBF) in the frontal, temporal, parietal and occipital lobes, thalamus and cerebellum using an autoradiographic method with a single blood sample. Brain CT demonstrated no abnormal findings other than a mild age-related atrophy in all patients except for one patient with a low-density area in the left cerebellar hemisphere due to an old hemorrhage, whereas SPECT revealed a decreased uptake of the tracer in various parts of the cerebral cortex of all patients, sometimes in an asymmetrical pattern. Absolute values of rCBF showed a significant decrease in all examined regions of the patients as against healthy controls (P<0.0001). In three patients, SPECT demonstrated a decreased uptake throughout the cerebral cortex on visual inspection, whereas absolute values of rCBF revealed an obvious decrease of the uptake also in the thalamus and cerebellum. These results suggest that SPECT with quantification of rCBF using 123I-IMP might be a sensitive and useful technique not only for detecting a focal metabolic dysfunction but also for diagnosis in the early stage of CJD.

Aged↗

PubMed1999

Spectrogram enhancement algorithm: a soft thresholding-based approach.

Enhancing the spectrogram by denoising the Doppler ultrasound signal is a preliminary step, and important for further processing. Because the spectrogram may be based on the short-time fast Fourier transform (FFT) of the Doppler ultrasound signal, whose power spectrum density is time-varying, traditional denoising algorithms that simply optimize the mean-squared error are not appropriate, and they may exhibit considerable undesirable, noise-induced frequency components. A soft thresholding-based denoising algorithm is put forward in this paper, that achieves almost the minimax mean square error (MSE) over a wide range of function classes having norms measuring smoothness (i.e., it meets both the requirement of smoothness and MSE). Due to the importance of noise level estimation while applying this method, several robust L-estimators are compared and the median absolute deviation (MAD) method is chosen to estimate the noise level. The simulation study shows better performance of the later algorithm under various quantification measures, compared to the FFT thresholding and the hard thresholding wavelet method, and the results of clinical data also confirm it.

Algorithms↗

PubMed1986

Adipose tissue cellularity and growth characteristics of unselected and selected broilers: implications for the development of body fat.

Chicks from large and small eggs were used to increase body weight range within samples of unselected Athens-Canadian (AC) and commercial Cobb (C) broilers. At 54 days of age, representatives of each sex and broiler stock obtained from the large and small eggs were killed. Indices of whole body, muscle, fat, and bone growth were taken. Samples of abdominal fat were fixed with osmium tetroxide for electronic quantification of adipocyte number and size distribution. Broiler stock, egg size, and sex affected all indices of muscle and bone growth on an absolute basis, but only broiler stock significantly affected abdominal fat pad development. Muscle and fat weight, expressed as a proportion of body weight, were larger in C broilers. Abdominal adipocyte number was greater in C than AC (126.0 +/- 10.0 vs. 90.9 +/- 7.7 million, P less than .01), but the greater adiposity of C was associated with an increase in adipocyte size. If the mean adipocyte volume of C (120.4 +/- 8.5 pl) was reduced to the mean adipocyte volume of AC (53.8 +/- 6.5 pl), proportional weight of the abdominal pad of C would have been smaller than proportional pad weight of AC. The problem of excessive abdominal fat deposition in the selected broiler stock appears related to factors that affect control of adipocyte size and body composition.

Adipose Tissue↗

PubMed1981

Quantitative 99mTechnetium cerebral circulation time in brain infarction. Its relation to clinical findings, electroencephalograms and conventional radionuclide studies.

Four circulation time parameters were measured by intravenously injected 99mTechnetium and a gamma camera in 183 patients displaying a unilateral supratentorial brain infarction. The mean values of all the calculated circulation time parameters in the infarcted hemisphere were significantly slower than those of the contralateral hemispheres. The difference between the hemispheres proved a more sensitive parameter than absolute values. Both the quantitative circulation time differences between the hemispheres and the absolute circulation time values showed significant correlations with several clinical findings, e.g. severity of infarction, recovery from infarction, and patient's age. However, quantification gave only a minor addition to the number of the patients with abnormalities detected by routine static and dynamic brain scintigrams. Though the value of the quantitative intravenous 99mTechnetium method in routine clinical work is limited, it provides valuable information on the haemodynamics in brain infarction, e.g. the persistence of measurable asymmetry suggesting decreased function even of non-infarcted parts of the affected hemisphere ("deafferentiation").

Adult↗