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At least 703 records · Page 39Linked to original sources
PubMed1988

Water quality control trials: statistical tables for direct comparison between membrane filtration bacterial counts and the multiple tube method with a description of the bacteriological method.

Experiments in the quality control of water samples are being conducted in the Public Health Laboratory Service and the water industry in the United Kingdom. The number of distributions which have been made is 7 and 92 laboratories are now participating. The methods used for preparing and distributing samples are described. Some participating laboratories use the multiple tube method and some use membrane filtration to assess the presence of coliforms and Escherichia coli. The results are, therefore, a mixture of estimated numbers and direct colony counts. In order to compare results from these two different laboratory methods statistical tables have been compiled to show the most likely multiple tube result corresponding to each colony count. Tables relating to two commonly used tenfold dilution series are presented. To illustrate how these tables may be used we present results from a typical quality control distribution. The analyses of these results are generally satisfactory but show a tendency for lower counts using the membrane filtration method and more false negative results with E. coli counts.

Colony Count, Microbial↗
PubMedDate not supplied

Preparation of 18F-human serum albumin: a simple and efficient protein labeling method with 18F using a hydrazone-formation method.

18F-labeling of proteins and peptides is important for positron emission tomography (PET). Although there are many methods for the labeling of proteins with (18)F, most of these are characterized by complicated procedures or low yields. Here, we report a novel and simple method which includes the preparation of [18F]fluorobenzaldehyde ([18F]FBA) and successive conjugation with hydrazinonicotinic acid-human serum albumin conjugate (HYNIC-HSA) via hydrazone formation. HYNIC-HSA, which can also be used for labeling with (99m)Tc, was prepared via reaction with N-hydroxysuccinimide (NHS) or tetrafluorophenyl (TFP) esters of HYNIC with HSA. No-carrier-added [18F]FBA was prepared by the nucleophilic substitution of [18F]fluoride to 4-trimethylammonium benzaldehyde triflate in the presence of tetrabutylammonium bicarbonate. [18F]FBA was purified by passing ion exchange cartridges (IC-H and QMA) and was adsorbed to a C18 Sep-Pak cartridge. The adsorbed [18F]FBA was then eluted with 50% ethanol. HYNIC-HSA was added to the solution and conjugated with [18F]FBA via hydrazone formation. 18F-HSA was purified with a PD10 column. Biodistribution of 18F-HSA, (99m)Tc-HSA, and [18F]FBA in mice were investigated at 10, 20, and 60 min after intravenous injection. The number of conjugated HYNIC molecules per HSA ranged from 5.2 to 23.2 depending on the reaction conditions. The labeling efficiency of 18F-FBA was 67 +/- 15.7%. The radiochemical purity after purification was over 99%. The conjugation efficiency of HYNIC-HSA with [18F]FBA was between 25% and 90%. The conjugation efficiency was observed to increase with increases in the number of conjugated HYNIC, the HYNIC-HSA concentration, or temperature. 18F-HSA exhibited a biodistribution pattern similar to that of (99m)Tc-HSA while [18F]FBA showed much lower blood activity than that of 18F-HSA and (99m)Tc-HSA. We concluded that 18F-HSA was successfully labeled using a novel method which involves hydrazone formation between [18F]FBA and HYNIC-HSA. This method can be applied to the 18F-labeling of other proteins or peptides.

Animals↗
PubMed2006

Modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (abts) method to measure antioxidant capacity of Selected small fruits and comparison to ferric reducing antioxidant power (FRAP) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) methods.

The measurement of antioxidant capacity in fruits differs from that of other biological samples due to their low pH and very low lipophilic antioxidant capacity. In this report, we present a modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method for fruits and compare its performance with the other commonly used antioxidant methods of 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). The antioxidant capacity and reaction kinetics of four phenolic compounds, two antioxidant standards, and five fruits were also investigated. The modified ABTS method prepared at a pH of 4.5 with sodium acetate buffer is highly stable and easily applied to fruit samples as compared to the standard (pH 7.4) version. The measured antioxidant capacity of samples varied with the assay method used, pH, and time of reaction. Traditional antioxidant standards (trolox, ascorbic acid) displayed stable, simple reaction kinetics, which allowed end point analysis with all of assays. Of the phenolic compounds examined, chlorogenic and caffeic acids exhibited the most complex reaction kinetics and reaction rates that precluded end point analysis while gallic acid and quercetin reached stable end points. All fruit extracts exhibited complex and varied kinetics and required long reaction times to approach an end point. Because the antioxidant capacity of fruit extracts is a function of the array of individual antioxidants present, accurate comparisons among fruit samples require that reaction times be standardized and of sufficient length to reach steady state conditions and that more than one assay be used to describe the total antioxidant activity of fruit samples.

Antioxidants↗
PubMed2006

Accurate and efficient method for predicting thermochemistry of furans and ortho-arynes: expansion of the bond-centered group additivity method.

The bond-centered group additivity method (BCGA) method for the estimation of the thermochemical properties of polycyclic aromatic molecules is expanded to aromatic molecules containing furan ring(s) and ortho-arynes. The method is based on enthalpies of formation (deltaH(o)f), entropies (S(o)298), and heat capacities (C(o)p) obtained from B3LYP/6-31G(d) calculations. The enthalpies of formation were obtained using a set of homodesmic reactions that include only aromatic molecules as the reference. Two new atom-centered groups are defined for the description of furan ring(s) and ortho-arynes, leading to the addition of 17 new bond-centered groups to the BCGA method. The deltaH(o)f, S(o)298, and C(o)p contributions of these bond-centered groups is derived.

Journal Article↗
PubMed1995

A new method for estimating dermal absorption from chemical exposure. 3. Compared with steady-state methods for prediction and data analysis.

PURPOSE: This paper compares unsteady-state and steady-state methods for estimating dermal absorption or analyzing dermal absorption data. The unsteady-state method accounts for the larger absorption rates during short exposure times as well as the hydrophilic barrier which the viable epidermis presents to lipophilic chemicals. METHODS: Example calculations for dermal absorption from aqueous solutions are presented for five environmentally relevant chemicals with molecular weights between 50 and 410 and log10Kow between 0.91 and 6.8: chloromethane, chloroform, chlordane, 2,3,7,8-TCDD, and dibenz(a,h)anthracene. Also, the new method is used to evaluate experimental procedures and data analyses of in vivo and in vitro permeation measurements. RESULTS: In the five example cases, we show that the steady-state approach significantly underestimated the dermal absorption. Also, calculating permeability values from cumulative absorption data measured for exposure periods less than 18 times the stratum corneum lag time will overestimate the actual permeability. CONCLUSIONS: In general, steady-state predictions of dermal absorption will underestimate dermal absorption predictions which consider unsteady-state conditions. Permeability values calculated from data sets which include unsteady-state data will be incorrect. Strategies for analyzing in vitro diffusion cell experiments and confirming steady state are described.

Animals↗
PubMed1984

Measurement of cerebral blood flow using bolus inhalation of C15O2 and positron emission tomography: description of the method and its comparison with the C15O2 continuous inhalation method.

This article describes a rapid method for the regional measurement of cerebral blood flow using a single breath of C15O2 and positron emission tomography. The technique is based on the bolus distribution principle and utilises a reference table for the calculation of flow. Seven subjects were studied using both this method and the C15O2 continuous inhalation steady-state technique. The single-breath method gave flow values 20% higher than those obtained using the steady-state method. A simulation study was performed in an attempt to define the reasons for the difference between the two techniques. Estimations were made of identified sources of error in the measurement of regional cerebral blood flow using the single-breath technique and compared with results from a similar study previously described for the steady-state technique. However, further comparative studies will be necessary to satisfactorily explain the difference between both techniques.

Adult↗
PubMed1990

A new method to measure brain serotonin synthesis in vivo. II. A practical autoradiographic method tested in normal and lithium-treated rats.

We describe here a practical autoradiographic method to estimate the rate of serotonin synthesis in brain. A two-time point method (60 and 150 min after injection of alpha-[14C]methyl-L-tryptophan) was first evaluated in 14 normal rats (7 at each time point). After this the method was tested in lithium-treated rats. In normal rats the rate of serotonin synthesis measured by the two-time point method generally correlated with known concentrations of tryptophan hydroxylase. The rate of synthesis in lithium-treated rats was compared with that in sham-treated rats (NaCl treatment). The results showed a significant increase in the synthesis rate in some cerebral structures. The greatest increases in the serotonin synthesis rate, attributable to the lithium treatment, were observed in the parietal cortex (52%) and caudate nucleus (47%). This is the first investigation to demonstrate, with autoradiographic resolution (approximately 100 microns), the differential changes in the rate of serotonin synthesis in the brain. Lithium had no significant effect on the rate of synthesis in the pineal gland.

Animals↗
PubMedDate not supplied

Simplification of the methods for adding and removing glycerol during freeze-preservation of human red blood cells with the high or low glycerol methods: biochemical modification prior to freezing.

Simple methods have been developed for adding and removing glycerol during freeze-preservation with 20 per cent W/V glycerol at minus 150 C, or with 40 per cent W/V glycerol at minus 80 C. A one-step method with a 35 per cent W/V glycerol solution is used to prepare 20 per cent W/V glycerolized red blood cells, and a two-step method with a 57 per cent W/V glycerol solution is used to prepare 40 per cent W/V glycerolized red blood cells. The systems for washing glycerolized red blood cells have been simplified. This method consists of dilution of the thawed glycerolized red blood cells prior to recovery, followed by on-line dilution of these red blood cells with wash solutions during continuous flow centrifugation. This can be done in any of three commercially available washing systems, and they all use the same sodium chloride solutions. For the 40 per cent W/V glycerolized red blood cells, this process takes about 30 minutes and uses 2.2 to 3.2 liters of the sodium chloride solutions, whereas the 20 per cent W/V glycerolized red blood cells can be processed in about 20 minutes using 1.5 to 2.5 liters. After storage in CPD for three days at 4 C, red blood cells can be freeze-preserved with 40 per cent W/V glycerol at minus 80 C or with 20 per cent W/V glycerol at minus 150 C. When the thawed red blood cells are washed in the Fenwal Elutramatic, the IBM Blood Processor, or the Haemonetics Blood Processor and stored at 4 C in sodium chloride-glucose-phosphate for at least 24 hours before transfusion, they have excellent posttransfusion survival values and normal or slightly decreased oxygen transport function. Alternatively, these red blood cells can be rejuvenated before freeze-preservation so that their 2,3-DPG levels are increased and their affinity for oxygen is reduced. Red blood cells that are stored in CPD at 4 C for as long as 28 days can be rejuvenated with a solution containing pyruvate, inosine, glucose, phosphate, and adenine (PIGPA, Solution A) before freeze-preservation with 40 per cent W/V glycerol at minus 80 C. Any one of the above systems can be used to wash these red blood cells and they can be stored at 4 C in a sodium.

Adenine↗
PubMed2003

A digital method of sperm immobilization test: comparison to the conventional method.

Antisperm antibodies have been found in infertile patients and those causing immobilization of sperm are considered to be closely related to unexplained infertility. These antibodies are usually identified by a sperm immobilization test which involves counting motile sperm under microscope. This test is subjective as it relies on the judgement of the examiner with respect to sperm motility. In this study, we analyzed motile sperm by a digital method using Sperm Quality Analyzer. The results were compared with those obtained by the conventional method. We found that the two methods yielded identical results, with 14 of 66 samples tested being positive and 52 negative for sperm immobilizing antibodies. These results show that the digital method is objective and of value in the measurement of motile sperm in determination of sperm immobilizing antibodies.

Agglutination Tests↗
PubMed2001

The Littler line method and the area under a Gaussian curve: a new method of assessing digital range of motion.

A new method of measuring digital range of motion (the Littler line method) is presented. When a Gaussian curve is centered over the Littler line and the appropriate area under the curve is computed, this area can provide a measure of the functional range of motion regained by an injured digit. Seventeen children (24 digits) with flexor tendon injuries were evaluated at an average follow-up period of 58 months (range, 12-121 months). The Littler line/Gaussian curve method was found to be more reproducible than total active motion, particularly in zone I and II injuries. This method can serve as a more meaningful functional assessment tool than a linear measurement such as total active motion, because it emphasizes digital motion in the mid-ranges of digital motion. (J Hand Surg 2001;26A:23-30.

Adolescent↗
PubMed1978

[Quantitative functional analysis of the left ventricle in coronary heart disease: an evaluation of current methods. I description of basic methods and definition of normal range (author's transl)].

The present work consists of an evaluation of quantitative laevocardiographic methods of analysis in coronary heart disease. An attempt has been made to find a correlation between the laevocardiographic results and the extent of coronary artery disease, heart size on a conventional chest X-ray with left ventricular end-diastolic pressure. In the first part, basic methods are described, particularly the laevocardiographic area-length-method of Dodge. The accuracy of the procedure and its statistical methods are discussed in detail.

Coronary Disease↗
PubMed1988

[Cotton thread method for measuring tear secretion, suitable for soft contact lens wearers (method no. 3)].

Two methods of measuring lacrimation with a cotton thread and fluorescein have been described hitherto. Method 3 is intended for testing lacrimal flow in wearers of soft contact lenses. Fluorescent paper can be used to facilitate the measuring procedure. The method has been shown to be reliable in numerous control tests on subjects with normal eyes and in comparisons with the authors' methods 1 and 2. With the test, values of less than 5 mm indicate severe lacrimal deficiencies.

Adolescent↗
PubMed2004

A local second-order Møller-Plesset method with localized orbitals: a parallelized efficient electron correlation method.

Using orthogonal localized occupied orbitals we have developed and implemented a parallelized local second-order Møller-Plesset (MP2) method based on the idea developed by Head-Gordon and co-workers. A subset of nonorthogonal correlation functions (the orbital domain) was assigned to each of the localized occupied orbitals using a distance criterion and excitations from localized occupied orbitals that were arranged into subsets. The correlation energy was estimated using a partial diagonalization and an iterative efficient method for solving large-scale linear equations. Some illustrative calculations are provided for molecules with up to 1484 Cartesian basis sets. The orbital domain sizes were found to be independent of the molecular size, and the present local MP2 method covered about 98%-99% of the correlation energy of the conventional canonical MP2 method.

Journal Article↗
PubMed1985

The identity model and factors controlling the superiority of the study-test method over the anticipation method.

Short-term memory (STM) and long-term memory (LTM) components are assumed to overlap in such a way that the response reflects predominantly STM components in short retention intervals but LTM ones in long retention intervals. Based on the STM and LTM overlap hypothesis, the identity model postulates that basic processes per study, test, and intervening study and test events as well as intercycle intervals, respectively, are the same for both anticipation and study-test methods in cued (paired-associate) recall and recognition (verbal discrimination learning). A crucial difference between the two methods is the differential retention interval distribution (containing an overlap area). Amounts of STM components in the short-term store (STS), that is, critical items, seem to control the varied superiority of the study-test method over the anticipation method. This is directly linked to the learning difficulty dimension, which in turn is determined by such variables as list length, learning materials, exposure durations (presentation rates), acquisition stages, learning ability, developmental stages (ages), and others.

Adolescent↗
PubMed1991

A single plasma sample method for estimation of the glomerular filtration rate in infants and children using iohexol, II: Establishment of the optimal plasma sampling time and a comparison with the 99Tcm-DTPA method.

The glomerular filtration rate (GFR) can be determined from the plasma disappearance rate of the non-ionic contrast medium iohexol. A preceding study established the empirical formulae enabling the development of a single plasma sample method for estimation of GFR in infants and children. In the present study the validity of these empirical formulae was confirmed in examinations in 143 patients. The results of the single plasma sample method were similar to those of a standard 99Tcm-DTPA method, and also with those of a two plasma sample iohexol method. Evaluation of the results obtained with plasma sampling 1 h, 2 h, 3 h and 4 h after the injection of the contrast medium showed that the optimal sampling time was about 3 h after the injection.

Adolescent↗
PubMed1999

Biokinetics of the monoclonal antibodies MOv 18, OV 185 and OV 197 labelled with 125I according to the m-MeATE method or the Iodogen method in nude mice with ovarian cancer xenografts.

The biodistribution of the radiolabelled monoclonal antibodies MOv18, OV185 and OV197 in nude mice with subcutaneous tumours of the human ovarian cancer cell line OVCAR3 was investigated. The early uptake of MOv18 (1-24 h) and the uptake in relation to tumour size were also studied. The antibodies were labelled with 125I according to the Iodogen method or the m-MeATE method, the latter also being suitable for labelling with 211Astatine. The tumour/blood ratio and the localization index for Mov 18 72 h after antibody injection were 2.21 +/- 0.25 and 4.62 +/- 1.27, respectively. This is significantly higher than for the other two specific antibodies. The early tumour uptake of MOv18 was low with a tumour/blood ratio of 0.23 +/- 0.04 after 6 h, and the uptake was higher in small tumours. The two labelling methods were found to be equivalent. We conclude that MOv18 labelled according the m-MeATE method should be suitable for further therapeutic studies with 211Astatine in nude mice.

Animals↗
PubMed2004

Validation of a capillary zone electrophoresis method for determination of rimantadine hydrochloride in Rimantadin100 tablets and the method application to dissolution test monitoring.

A capillary zone electrophoretic method with indirect UV-detection for determination of rimantadine, an antiviral drug against influenza A, in tablets was validated. Instrumental precision, the method precision, accuracy, calibration curve linearity, selectivity, robustness, and time stability of the sample and the standard were tested. The method was also applied to monitor dissolution tests of the tablets. The possibility of addition of an internal standard for improvement of the method precision was discussed.

Electrophoresis, Capillary↗
PubMed2006

Manual methods are suboptimal compared with automated methods for cleaning of single-use biopsy forceps.

OBJECTIVE: Most reusable biopsy forceps and all of the currently available single-use biopsy forceps do not have a port that allows fluid flow down the inner tubular shaft of the device. Reusable biopsy forceps are widely used and reprocessed in healthcare facilities, and single-use biopsy forceps are reprocessed either in-house (eg, in Canada and Japan) or by third-party reprocessors (eg, in the United States). The objective of this study was to determine the cleaning efficacy of automated narrow-lumen sonic irrigation cleaning, sonication-only cleaning, and manual cleaning for biopsy forceps. DESIGN: A simulated-use study was performed by inoculating the inner channel of single-use biopsy forceps with artificial test soil containing both Enterococcus faecalis and Geobacillus stearothermophilus at concentrations of 10(6) colony-forming units per milliliter. The cleaning methods evaluated were manual cleaning, sonication-only cleaning, and "retroflush" cleaning by an automated narrow-lumen irrigator. Bioburden and organic soil reduction after washing was evaluated. Forceps used in biopsies of patients were also tested to determine the worst-case soiling levels. RESULTS: Only retroflush irrigation cleaning could effectively remove material from within the shaft portion of the biopsy forceps: it achieved an average reduction of more than 95% in levels of protein, hemoglobin, carbohydrate, and endotoxin. However, even this method of cleaning was not totally effective, as only a 2 log10 reduction in bioburden could be achieved, and there were low residual levels of hemoglobin and carbohydrate. CONCLUSION: The data from this evaluation indicate that manual and sonication-only cleaning methods for biopsy forceps were totally ineffective in removing material from within the biopsy forceps. Even the use of retroflush cleaning was not totally effective. These findings suggest that in-hospital reprocessing of biopsy forceps with currently available equipment and cleaning methods is suboptimal.

Automation↗