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At least 1,153 records · Page 64Linked to original sources
PubMed2005

A method for surveying and classifying Leuconostoc spp. glucansucrases according to strain-dependent acceptor product patterns.

A number of Leuconostoc spp. strains were screened for their ability to produce glucansucrases and carry out acceptor reactions with maltose. Acceptor products were analyzed by thin-layer chromatography (TLC) and it was discovered that they could be grouped into four distinct categories based on oligosaccharide product patterns. These patterns corresponded with structural features of the dextrans each strain is reported to produce. Strains that produced a typical dextran-characterized by a predominantly linear alpha(1-->6)-linked D: -glucan chain with a low to moderate degree of branching-produced a homologous series of isomaltooligosaccharides via acceptor reactions. Strains that produced dextrans with moderate to high levels of alpha(1-->2) branch points, exemplified by NRRL B-1299, synthesized the same isomaltodextrins as well as another series of oligosaccharides migrating slightly faster in our TLC system. Strains that produced dextrans with higher levels of alpha(1-->3)-branches, such as NRRL B-742, synthesized isomaltodextrins plus a series of oligosaccharides that migrated slightly more slowly on TLC. And finally, strains known to produce alternansucrase produced isomaltodextrins plus oligoalternans. Within a given type, variability exists in the relative proportions of each product. The data presented here may be useful in selecting strains for the production of specific types of oligosaccharides, for example as prebiotics.

Carbohydrate Sequence↗
PubMed2006

A(max) is the best a-wave measure for classifying Abyssinian cat rod/cone dystrophy.

AIM: To see if any a-wave measure segregated normal cats from those affected by a recessively inherited Abyssinian rod/cone dystrophy more efficiently than a(max) to scotopic I(max). METHOD: A-waves to electroretinograms (ERGs) evoked by a 4 cd x s/m(2) scotopic flash were extracted from 241 ERG sessions using 108 cats. They were either wild type or from an affected Abyssinian stock. Fourty four were bred by back-crossing to have a 50% probability of being affected. Most were diagnosed by retinal appearance or by the pattern of loss in a long protocol ERG. Eight were still unclassified. The diagnostic efficiency of amplitudes at 7, 8, 9, and 10 ms and a(max), of a(max) peak time, age at testing, and the main components of principal components factor analysis were compared by scaling their ability to segregate affected and normal cats. RESULTS: Variance and overlap between the groups both decreased as time along the a-wave increased. The loading of each animal on the largest factor also gave considerable overlap. There was a small absolute separation between groups when a(max) itself was used. Age and peak time were uncorrelated with disease. The light intensity used could be calculated to be equivalent to one sufficient for about 75% of full saturation in man. CONCLUSION: A(max) is a simple measure that is already in routine clinical use. When the flash is very bright and the animal fully dark adapted, this single measure is the most efficient sign of this rod/cone degeneration and possibly of all degenerations involving rods.

Animals↗
PubMed1995

Classifying urban crashes for countermeasure development.

Efforts to reduce urban crash rates have been hampered by a lack of information about motor vehicle crash types. The present study is based on a systematic sample of 4,526 police crash reports from four urban areas. The sample was weighted to give each area equal representation. Diagrams and narrative descriptions from each report were reviewed, and the most common crash types based on precrash driver/vehicle behavior, were identified. Fourteen crash types were defined, and five of these were found to account for 76% of all crash events and 83% of injury crashes. Although the rank order of the five types differed from city to city, they accounted for the vast majority (69%-81%) of the crashes in each. Potential countermeasures are discussed based on the predominant crash types identified in this study. For example, ran traffic control crashes, the most common types, might be reduced by changes in signal timing, providing all-red signal intervals, increasing sign visibility, and increasing sight distances.

Accidents, Traffic↗
PubMed1984

Pure erythrocytosis classified according to erythropoietin titers.

Erythropoietin titers, measured by bioassay of plasma extracts in hypertransfused mice, were determined in 162 patients with absolute erythrocytosis, and the results were correlated with the clinical diagnosis. Fifty-two patients met the diagnostic criteria for polycythemia vera, and all had low or nonmeasurable erythropoietin titers. Of the remaining 110 patients, 62 were suspected clinically as having secondary polycythemia. However, 15 had low erythropoietin titers, casting doubt on the accuracy of the clinical diagnosis. The pathogenesis of the erythrocytosis in the last 48 patients was unknown, and they were designated clinically as having pure erythrocytosis. However, in 20, the erythropoietin titers were increased, and in 28, the titers were low, suggesting that they belonged to at least two different groups. Using erythropoietin titers in the classification of absolute erythrocytosis, the first group should be added to the category of patients with secondary polycythemia as a subgroup with disease due to idiopathic overproduction of erythropoietin (hypererythropoietinemia or essential erythrocytosis). The second group should be added as a subgroup of patients with primary polycythemia under the term erythremia.

Animals↗
PubMed1992

Axon types classified by morphometric and multivariate analysis in the rat optic nerve.

Calibers of the rat optic nerve axons distribute unimodally and it is difficult to distinguish groups among them. However, these fibers arose from 3 types of ganglion cells and showed 3 conduction velocities. Performing a cluster analysis over several ultrastructural parameters we found 3 main groups of fibers. These groups are present in a very similar proportion to the ganglion cells groups described in the rat retina.

Animals↗
PubMed1982

Binding of polychlorinated biphenyls classified as either phenobarbitone-, 3-methylcholanthrene- or mixed-type inducers to cytosolic Ah receptor.

It has been postulated that reversible, high-affinity binding of 3-methylcholanthrene(MC)-type inducers to a receptor protein (the Ah receptor) in hepatic cytosol is essential for induction of aryl hydrocarbon hydroxylase (AHH) enzymic activity. To test this postulate, the binding affinities of 16 highly-purified, synthetic chlorinated biphenyl (PCB) congeners, which have been categorized either as phenobarbitone(PB)-, MC- or mixed (PB + MC)-type inducers of cytochrome P-450-dependent monooxygenase have been examined. The affinity of individual biphenyl congeners for the receptor was determined by their competition with 2,3,7,8-[3H]tetrachlorodibenzo-p-dioxin ([3H]TCDD) for specific cytosolic binding sites as measured by sucrose density gradient analysis following dextran-charcoal treatment. This assay demonstrates (a) that the receptor binds with highest affinity to 3,3', 4,4',5-pentachlorobiphenyl and 3,3',4,4'-tetrachlorobiphenyl ('pure MC-like' inducers); (b) mixed-type PCB inducers also bind to the receptor but with an affinity (average EC50-value of 8.6 microM) lower than that for 3,3',4,4',5-pentachlorobiphenyl; this corresponds with their relatively lower potencies as AHH inducers; (c) the receptor binds 2,2',4,4'-tetra-, 2,3,4,5-tetra-, 2,2',4,4',5,5'-hexa- and 2,3',4,4',5',6-hexachlorobiphenyl at high concentrations (0.1 mM), whereas PB fails to bind, even at a concentration of 10 mM. All PCBs tested competed with [3H]TCDD for Ah receptor, but there was a great variation in their relative binding affinities. The fact that two chlorinated biphenyls classed as 'PB-like' inducers and two chlorinated biphenyls which are neither 'PB- nor MC-type' inducers competed, coupled with the fact that PB did not bind to the receptor suggest that chemicals other than "pure MC-type' inducers can bind to the cytosolic receptor. Affinity of the binding dictates the relative potency of given PCB congeners as inducers of cytochrome P-448.

Animals↗
PubMed1986

A new ECG classifier based on linear prediction techniques.

A longstanding tradition in automatic ECG classification has been the use of conventional features (amplitudes, duration, etc.) as waveform descriptors for pattern discrimination purposes. This paper presents an alternative approach in statistical ECG classification. It is based on the use of linear prediction coefficients, a sort of "abstract" features which, as waveform descriptors, enjoy the desirable property of whole-signal dependency, being rather insensitive to high-frequency noise. Experimental results obtained on 400 ECGs distributed by four clinical groups according to clinicopathological data (normal, myocardial infarction, right and left hypertrophies) show interesting potentialities of this new method, namely a classification error for equal class prevalences (30%) significantly lower than by using conventional features. Classification and cluster separability results are presented and discussed as well as the viability of the new method in a clinical environment.

Adolescent↗