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At least 811 records · Page 45Linked to original sources
PubMed1985

A revised method of age determination using the os pubis, with a review and tests of accuracy of other current methods of pubic symphyseal aging.

All current standardized methods of age determination using the os pubis were tested by blind assessment of a skeletal sample with documented ages (from the Todd collection; N = 96). No demographic data (sex, age, race, age composition) were known to the assessors prior to completion of the test. Results showed the Todd method to be more reliable than more recent component techniques and that all systems tended to underage. Therefore, modifications were made of the Todd system to eliminate this and other deficiencies, and a second test using a new sample was conducted (N = 109). The age distribution determined by the revised Todd method did not significantly differ from the actual age distribution of the second sample. Error due to race was nonsignificant. Biological stages of pubic metamorphosis are described and possible evolutionary specializations of the hominid symphysis are discussed. Revised standards for age determination are presented.

Adult↗
PubMedDate not supplied

Comparison of the erythrocyte partitioning method with two classical methods for estimating free drug fraction in plasma.

A modification of the erythrocyte partitioning method for the rapid estimation of plasma-free drug fractions (fu) is described and applied to five basic drugs. In the procedure, which uses readily available clinical laboratory equipment, fu is calculated from measurements of drug partitioning between plasma and erythrocytes, and between buffer and erythrocytes. Results obtained are compared with those from equilibrium dialysis or ultrafiltration techniques for amitriptyline, imipramine, quinidine, lidocaine, and propranolol. For each drug, the mean value of fu obtained with the erythrocyte partitioning procedure was not found to be significantly different from that determined by one of the two other classical techniques. The erythrocyte partitioning method lead to reproducible (mean C.V. = 6.25) and precise values of fu when compared to the other methods; its clinical application to lidocaine gave results which agreed with those obtained by equilibrium dialysis.

Blood Proteins↗
PubMed2001

Hidden-Markov methods for the analysis of single-molecule actomyosin displacement data: the variance-Hidden-Markov method.

In single-molecule experiments on the interaction between myosin and actin, mechanical events are embedded in Brownian noise. Methods of detecting events have progressed from simple manual detection of shifts in the position record to threshold-based selection of intermittent periods of reduction in noise. However, none of these methods provides a "best fit" to the data. We have developed a Hidden-Markov algorithm that assumes a simple kinetic model for the actin-myosin interaction and provides automatic, threshold-free, maximum-likelihood detection of events. The method is developed for the case of a weakly trapped actin-bead dumbbell interacting with a stationary myosin molecule (Finer, J. T., R. M. Simmons, and J. A. Spudich. 1994. Nature. 368:113-119). The algorithm operates on the variance of bead position signals in a running window, and is tested using Monte Carlo simulations to formulate ways of determining the optimum window width. The working stroke is derived and corrected for actin-bead link compliance. With experimental data, we find that modulation of myosin binding by the helical structure of the actin filament complicates the determination of the working stroke; however, under conditions that produce a Gaussian distribution of bound levels (cf. Molloy, J. E., J. E. Burns, J. Kendrick-Jones, R. T. Tregear, and D. C. S. White. 1995. Nature. 378:209-212), four experiments gave working strokes in the range 5.4-6.3 nm for rabbit skeletal muscle myosin S1.

Actin Cytoskeleton↗
PubMed1978

Specific method for serum creatinine determination based on ion exchange chromatography and an automated alkaline picrate reaction -- a proposed reference method.

A proposed reference method for serum creatinine has been developed under the auspices of the Committee on Reference Methods and Reference Materials of the Canadian Society of Clinical Chemists. A serum ultrafiltrate at pH 2.0 is applied through a closed sample loop injection system to a short column containing cationic resin of high resolving power. Elution with sodium citrate buffer by means of minipump at constant rate passes the eluate into alkaline picrate reagents in a continuous flow system (Technicon AAIII pump, AAII colorimeter 50 mm x 1.5 mm flow cell, narrow band width filter). The colour reaction peak is monitored visually to verify specificity and the area is calculated electronically. Specificity has been demonstrated by use of Jaffé-reactive substances such as glucose, sodium acetoacetate, L-ascorbic acid, pyruvic acid, L-dopa and glycocyamidine and also by use of an alternate colour reaction, sodium 3,5-dinitrobenzoate in place of alkaline picrate in the analysis of serum pools. Routine methods in common use, i.e., manual and automated alkaline picrate procedures, demonstrated a statistically significant high bias in interlaboratory studies in which this procedure was used for reference.

Autoanalysis↗
PubMed1984

A simple method for the calculation of low energy packings of alpha-helices--a threshold approximation. I. The use of the method to estimate the effects of amino acid substitutions, deletions and insertions in globins.

A simple method is developed for computing low energy packings in alpha-helical proteins. This method is based on a simplified representation of a protein molecule in which the backbone of the alpha-helix is represented by a cylinder and the side chains of the amino acids by hard spheres. The energy function includes hydrophobic, electrostatic and Van der Waals' interactions. This method is used to compute low energy packings of an assembly of the alpha-helices of a globin molecule. The effect of mutations, deletions and insertions of a single amino acid resulting in drastic distortion of the spatial structure of sperm whale myoglobin was studied. The results demonstrated that these events can produce a breakdown of the spatial structure of the protein molecule.

Amino Acids↗
PubMed2003

Ab initio structure determination of rofecoxib from powder diffraction data using molecular packing analysis method and direct space method.

Crystal structures of a COX-II inhibitor, rofecoxib (Vioxx) were solved ab initio from X-ray powder diffraction pattern using both molecular packing analysis and direct space methods. The X-ray powder pattern was indexed into a tetragonal cell. Packing energies were generated and analyzed in eight most frequently found tetragonal space groups. The two space groups with the lowest total energy, P4(1)2(1)2 and P4(3)2(1)2, were used for direct space method with a Monte-Carlo/Simulated Annealing searching algorithm. Structural solutions obtained from direct space method were evaluated using molecular packing energy analysis. The structures solved ab initio from this work were compared to the single crystal structure deposited in the Cambridge Structural Database.

Crystallization↗
PubMed1979

[Isotope methods in the diagnosis of venous disease. I. Methods of radionuclide venography (author's transl)].

The method of radionuclide venography is best determined by the localisation and type of suspected venous abnormality. The authors describe four methods using 99mTc microspheres and 99mTc-pertechnetate. Correlation of the isotope and angiographic findings in 150 patients indicated an accuracy of 90% for the isotope methods. The risks of radionuclide venography are discussed. Isotope venography is recommended as a simple, non-invasive technique.

Arm↗
PubMed1976

Comparison of serum calcium measurements with respect to five models of atomic absorption spectrometers using NBS-AACC calcium reference method and isotope-dilution mass spectrometry as the definitive method.

Utilizing the recently described reference method for calcium (NBS-AACC) and the recently developed definitive (referee) NBS method for serum calcium measurement by isotopedilution mass spectrometry (IDMS), an evaluation of five recent-model atomic absorption spectrometers was carried out. Under optimal conditions of instrument operation using aqueous standards, significant differences were found during the comparative analyses of three lyophilized pool samples and one liquid serum pool sample. Use of the NBS-AACC serum calcium protocol did not guarantee analytic results within +/- 2% of the IDMS value. In four of eight comparisons, differences from IDMS greater than 2% were observed. Several variables were studied to account for these differences. It was shown that a serum matrix, when present in standards used to bracket the unknown sample, reduced differences between instruments in four of four instances and improved the accuracy of the results from a range of -1.1 to +3.5% to +0.1 to +1.0%. It is concluded that a serum sample with a verified IDMS calcium value is a valuable tool that establishes an accurate and stable reference point for serum calcium measurement. The use of transfer-of-NBS-technology multipliers is suggested. Regional quality control serum pools and clinical chemistry survey sample materials that have been analyzed for calcium concentration by the NBS-IDMS definitive method are examples of these multipliers.

Calcium↗
PubMed1981

A comparative study of the peroxidase-antiperoxidase method and an avidin-biotin complex method for studying polypeptide hormones with radioimmunoassay antibodies.

A highly sensitive immunoenzymatic technic is presented. The method involves three sequential steps: (1) primary antibody, (2) biotin-labeled secondary antibody, and (3) avidin-biotin-peroxidase complex. Avidin, an egg white protein, has four binding sites for the low-molecular-weight vitamin biotin. Many moieties of biotin can be coupled to the peroxidase molecule. Thus, since a relatively large amount of avidin is incubated with biotin-labeled peroxidase, avidin serves as a link between biotin-peroxidase molecules; in turn, biotin-peroxidase serves as a link between avidin molecules. Consequently, this large lattice-like complex with biotin-binding capability can be attracted to the sites of biotin-labeled antibody, producing a superior staining sensitivity. Several commercially available radioimmunoassay antibodies (e.g., antiglucagon, prolactin, gastrin, growth hormone, and thyroid-stimulating hormone antibodies) were tested for immunohistochemical staining. The unlabeled antibody peroxidase-antiperoxidase method fails to stain gastrin or thyroid-stimulating secretory cells when using these antibodies, and a relatively high antibody concentration is required to produce a positive reaction for glucagon, prolactin, and growth hormone. In contrast, the avidin-biotin-peroxidase complex method successfully demonstrates polypeptide hormones even when antibodies are diluted 20 to 40 times.

Antibodies↗
PubMed1976

A comparison of two commerical methods for the identification of the Enterobacteriaceae--API 20E and the Enterotube--with conventional methods.

The API 20E, the Enterotube, and routine methods of Cowan and Steel were used in parallel to identify 245 members of the Enterobacteriaceae. The API 20E and conventional methods gave the same identification in all but 2 (0-8%) of the 245 organisms tested. The Enterotube correctly identified 85% of these organisms on the first testing. On re-testing those organisms incorrectly identified the Enterotube results agreed with the conventional ones in a further 20 (8%). There was no change in the identification obtained by the API or conventional methods. Further conventional sugar tests were necessary before final identification was available by the API system in 7 (3%) against 106 (47%) of the 226 organisms correctly identified by the Enterotube. The Enterotube relied on serological testing alone to distinguish between alternatives in 17 (7%) isolates. Other advantages and disadvantages of these systems are discussed.

Bacteriological Techniques↗
PubMedDate not supplied

Improved method for noninvasive measurement of regional cerebral blood flow by 133Xenon inhalation. Part I: description of method and normal values obtained in healthy volunteers.

A clinical method for noninvasive measurement of regional cerebral blood flow (rCBF) and blood volume (rCBV) is described, based on Obrist's 10 minute, desaturation method after 1 minute inhalation of 133Xe. Sixteen collimated probes are placed over both hemispheres and brain stem-cerebellar regions. End-tidal 133Xe curves are used for correction of recirculation. KEV discriminators are set to record gamma and x-ray activity separately. Values are printed out automatically by a computer on a brain map. Extracerebral contamination is reduced by 1) computing curves from gamma activity, 2) applying pressure on the scalp beneath the probes, 3) 1 minute inhalation of 133Xe and recording desaturation curves for 10 minutes, thereby minimizing slow clearance from extracranial tissues. Normal values for both fast and slow compartments are reproducible and are in good agreement with the carotid injection method. The speech dominant hemishpere has higher flow than the right under conditions described. Posterior portions of the cranium over the cerebellum and brain stem appear to have higher flow gray values than the cerebral cortex. Gray matter flow decreases with advancing age.

Adult↗
PubMedDate not supplied

An introduction to a Bayesian method for meta-analysis: The confidence profile method.

The Confidence Profile Method is a new Bayesian method that can be used to assess technologies where the available evidence involves a variety of experimental designs, types of outcomes, and effect measures; a variety of biases; combinations of biases and nested bases; uncertainty about biases; an underlying variability in the parameter of interest; indirect evidence; and technology families. The result of an analysis with the Confidence Profile Method is a posterior distribution for the parameter of interest, posterior distributions for other parameters, and a covariance matrix for all the parameters in the model. The posterior distributions incorporate all the uncertainty the assessor chooses to describe about any of the parameters used in the analysis.

Bayes Theorem↗
PubMed1983

A new method for quantitative analysis of thallium-201 myocardial image-"corrected" circumferential profile method.

A new method for computer-assisted quantitative analysis of a thallium (Tl)-201 myocardial image ("corrected" circumferential profile method) was described. Since the Tl-201 myocardial image of a normal subject is not homogeneous, an attempt was made to correct for this non-homogeneity. Three groups of subjects were studied, including 10 normal volunteers (group A, mean age of 27.5 years), 14 patients with atypical chest pain and normal coronary arteriogram (group B, mean age of 56.7 years) and 16 patients with first transmural myocardial infarction (group C, mean age of 71.0 years). The myocardial images were acquired at rest at anterior, left anterior oblique (30 degrees and 60 degrees) and left lateral projections. With a scintigram, the left ventricle was outlined and divided into 24 radial segments by radii drawn from the center of the left ventricle. Average radioactivity per pixel in normal subjects was obtained in each segment and normalized to the highest segment (= 100%). The ratio of 100% to the mean of normalized radioactivity in percent in each segment from 10 normal volunteers was calculated and designated as a correction factor for each segment. After the correction of average radioactivity per pixel in each segment using this correction factor and after relating it to the highest radioactive segment, the mean (= 100%) and standard deviation (SD) were calculated and (100-4SD)% was defined as the normal lower limit. In the scintigram of groups B and C, "corrected" circumferential profiles were obtained from the regional radioactivity multiplied by the correction factor, normalized to the highest segment (100%) and compared with the lower normal limit. The ratio (%) of the area of patient's circumferential profile curve below the normal limit to the total area below the normal limit was obtained at each view and the sum of them was called the total "corrected" defect score. Infarct size analyzed by the "corrected" circumferential profile method correlated well with that analyzed by visual interpretation, and was useful in differentiating group C from group B.

Adult↗
PubMed1976

[Comparison between the official indirect method and the direct method of control of vaccines against sheep enterotoxemia].

The official methods of control of vaccines against sheep enterotoxemia are indirect in two ways : on the one hand they are carried out on animals for which the vaccine is not intended, and on the other hand they test only an immunological serum reaction. Another method consisting of direct testing by intravenous injection of toxin has been carried out on mice previously vaccinated with different doses. It has been shown that it is possible to obtain a certain level of protection giving a good dose-effect relation. However, immunity provided by this direct method is weak although the vaccine utilized is considered very efficacious with regard to the official norms of the direct test. These results, which are both encouraging and disappointing, will be the subject of a more intensive study of the different parameters in question.

Animals↗
PubMed1985

[Adaptation of the enzyme method to determine the cholesterol content of high density serum lipoproteins isolated using the precipitation method].

Negative interference was established of the precipitating reagent (heparin/MnCl2) for the isolation of HDL in the determination of serum concentration of high density lipoproteins--cholesterol by the enzyme CHOD-PAP method. The combining of enzyme-substrate reagent with 8,0 mmol/l EDTA eliminated the negative interference, but induced a lightly manifested increase of the optical density regardless of cholesterol concentration. That is the reason, the calibration of the enzimatic method is recommended to be performen with cholesterol standards, pretreated with precipitating reagent, analogically to serum. The analytical significance of the modified method was studied as regards reproducibility (VK = 0,88% with investigation in series and VK = 4,57% with investigation in time) and of accurary (test of Lord, L = 0,073 less than Lp less than 0,05).

Cholesterol, HDL↗
PubMed1982

[Review of the methods of determination of blood urea with continuous-flow analyzers and a proposal of a completely enzymatic UV method for urea by a continuous-flow analyzer].

After a brief review of the methods for determination of urea by continuous flow analyzers, a method is described based on the urease splitting of urea followed by NH3 reaction with alfa-ketoglutarate + NADH2 catalysed by GLDH. The method has been applied to continuous flow analyzers and seems to be promising.

Glutamate Dehydrogenase↗
PubMed1998

Genetico-mathematical analysis of the inheritance pattern of ulcer disease. A posteriori methods. The maximum likelihood method.

Inheritance pattern of ulcer disease was analysed genetico-mathematically using one of the a posteriori methods--the method of maximum likelihood. We studied the families of 351 hereditary predisposed probands of whom 57 with type II gastric ulcer disease, 27 with type III gastric ulcer disease and 267 with duodenal ulcer disease. The types of ulcer disease were determined according to H. Johnson. The analysis of the patients with duodenal ulcer also included the types of familial predisposition of the probands. The results yielded by the maximum likelihood method excluded to a great degree the possibility of monogenic transmission of ulcer disease. None to the three types of peptic ulcer showed autosomal recessive pattern of inheritance; it was not found even in the families with phenotypically healthy but hereditary predisposed parents. No evidence was found of autosomal dominant pattern of inheritance of the disease in all studied groups including the families with one sick parent. This is supported by the different values of the segregation coefficients in the families with one sick father and one sick mother. The absence of evidence for monogenic mode of inheritance of the disease indicated by the detailed genetico-mathematical analysis should be further evaluated by the criteria of polygenicity.

Humans↗