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At least 1,297 records · Page 72Linked to original sources
PubMed2000

Can viruses help us to understand and classify the MHC class I molecules at the maternal-fetal interface?

Placental expression of HLA-C, HLA-E, and HLA-G locus products is now well described. However, to date, the functional relevance of these MHC class I products at the maternal-fetal interface is incompletely described. We propose here that HLA-C, -E, and -G comprise a distinct and cohesive group of MHC class I products. This hypothesis is supported by a growing body of data, including that obtained through the study of viral immune evasion. Continued investigation of viral interactions with MHC class I products promises to help us to define those specific attributes of HLA-C, -E, and -G that define their common characteristics.

Cytomegalovirus↗
PubMed1998

Attempts to classify dependence-liable drugs by using a simple drug-discrimination test in mice.

1. In a simple discrimination test using a two-compartment shuttle box with mice, we examined the action properties of dependence-liable drugs. In mice trained to discriminate morphine from saline, neither methamphetamine (MAP) nor cocaine (COCA) was generalized to the discriminative stimulus effects of morphine. 2. Similarly, in mice trained to discriminate MAP from saline, COCA, which is known to have neuronal mechanisms in common with MAP, was generalized to the stimulus effects of MAP, but morphine was not. 3. Dihydroetorphine (DHE), which has receptor mechanisms in common with morphine, was generalized to the discriminative stimulus effects of morphine, whereas it was not generalized to the effects of MAP. Thus, the present discrimination test might be useful for the first screening of compounds with unknown neuronal mechanisms, particularly for classification into groups having separate neuropharmacological mechanisms in common.

Analgesics, Opioid↗
PubMed2002

Chemical responsiveness and histochemical phenotype of electrophysiologically classified cells of the adult rat dorsal root ganglion.

Whole cell patch recordings were obtained from medium diameter (35-45 microm) dorsal root ganglion neurons. Using electrophysiological parameters, we were able to subclassify acutely dissociated dorsal root ganglion cells into three uniform (types 5, 6 and 9) and one mixed class (type 8) of neurons. All subtypes (types 5, 6, 8 and 9) had broad action potentials (7.0+/-0.2, 5.2+/-0.4, 7.3+/-0.5 and 6.0+/-0.4 ms) and exceptionally long afterhyperpolarizations (112+/-9, 178+/-19, 124+/-31 and 204+/-33 ms). Long afterhyperpolarizations have been linked to mechanically insensitive (silent) nociceptors by other laboratories [Djouhri et al., J. Physiol. 513 (1998) 857-872]. Chemosensitivity varied among cell classes. Cell types 5, 8 and 9 were capsaicin sensitive (45+/-13, 87+/-30 and 28+/-13 pA/pF; 5 microM) groups, while the type 6 cell was capsaicin insensitive. All cell types expressed ASIC-like (acid sensing ion channel) amiloride sensitive, proton-activated currents with a threshold of pH 6.8 and a peak near pH 5.0. All medium sized cells were sensitive to ATP (50 microM) and exhibited the 'mixed' form of ATP-gated current [Burgard et al., J. Neurophysiol. 82 (1999) 1590-1598; Grubb and Evans, Eur. J. Neurosci. 11 (1999) 149-154]. Immunohistochemistry performed on individual cells indicated the expression of both P2X(1) and P2X(3) subunits. Electrophysiologically defined classes were histochemically uniform. All types were examined for the presence of substance P (SP), calcitonin gene related peptide (CGRP) and binding of isolectin B4 (IB4). All subtypes expressed CGRP immunoreactivity. Types 5 and 8 co-expressed SP and CGRP immunoreactivity and also bound IB4. Subtypes 6 and 9 were positive for neurofilament m. It is likely that these cells represent major classes of myelinated and unmyelinated peptide expressing nociceptors.

Animals↗
PubMed2000

Classifying amino acids as gluco(glyco)genic, ketogenic, or both.

Eleven popular and recent biochemistry textbooks were examined and compared concerning the classification of amino acids as being gluco(glyco)genic, ketogenic, or both. The main differences concerned mostly two amino acids, threonine, which in some cases is considered only gluco(glyco)genic and in others both gluco(glyco)-ketogenic, and lysine, which is considered chiefly ketogenic, but in two cases is reported as being gluco(glyco)-ketogenic. Some more mistakes, discrepancies and curiosities among different textbooks are also reported. Biochemistry textbook authors and teachers should be aware of this situation to avoid any confusion, especially among students.

Journal Article↗
PubMed1982

The impact of growth pattern on survival in non-Hodgkin's lymphomas classified according to Lukes and Collins.

203 cases of non-Hodgkin's lymphomas assigned as follicle centre cell (FCC) type according to the classification of Lukes and Collins (1975) were analyzed according to growth pattern. Nodular cases had a better prognosis than diffuse ones even within a certain cell type. The abundance of parafollicular lymphocytes was a better criterium of nodularity than prominence of venules. Degrees of nodularity was best scored according to distribution of diffuse and nodular areas. Prognosis was better with a higher degree of nodular growth even within a certain cytological cell type. Therefore it is proposed that scoring according to different degrees of nodularity has a high prognostic impact and could be an alternative to scoring according to cell type within the group of follicle centre cell lymphomas.

Humans↗
PubMed1999

Classifying serial killers.

We attempted to match the appearance and demeanor of 27 serial killers to the postmortem 'signatures' found on their victims' bodies. Our results suggest that a link may exist between postmortem signatures and two complementary appearance-demeanor types.

Autopsy↗
PubMed2001

Discrimination functions: can they be used to classify singing voices?

Researchers long have searched for invariant acoustic features that can be used to identify singing voice categories or even individual singers. Few researchers have examined how listeners perceive singing voice categories or individual voices. Timbre, the most studied perceptual dimension of the singing voice, is generally believed to vary systematically between singing voice categories but is often assumed to be invariant with an individual singer. To test this assumption, 2 mezzo-sopranos and 2 sopranos were recorded singing the vowel /a/ on the pitches A3, C4, G4, B4, F5, and A5. Trials of three stimuli were constructed. Two of the three stimuli in each trial were produced by the same singer at two different pitches (X1 and X2), while the third stimulus was produced by a different singer (Y). Three X1X2 conditions were created: (1) G4, B4; (2) C4, F5; and (3) A3, A5. For each singer and each condition, Y was varied across the three remaining singers and across all six pitches. Experienced and inexperienced listeners were asked to identify which stimulus was produced by the "odd" person. The ability to correctly choose the odd person varied greatly depending on pitch factors, suggesting that the traditional concept of an invariant timbre associated with a singer is inaccurate and that vocal timbre must be conceptualized in terms of transformations in perceived quality that occur across an individual singer's range and/or registers.

Adult↗
PubMed2001

Comparing Bayesian neural network algorithms for classifying segmented outdoor images.

In this paper we investigate the Bayesian training of neural networks for region labelling of segmented outdoor scenes; the data are drawn from the Sowerby Image Database of British Aerospace. Neural networks are trained with two Bayesian methods, (i) the evidence framework of MacKay (1992a,b) and (ii) a Markov Chain Monte Carlo method due to Neal (1996). The performance of the two methods is compared to evaluating the empirical learning curves of neural networks trained with the two methods. We also investigate the use of the Automatic Relevance Determination method for input feature selection.

Algorithms↗
PubMed1998

The Theoretical and Experimental Status of the n-tuple Classifier.

A number of theoretical approaches related to the n-tuple classification system are reviewed including Kanerva's SDM, the n-tuple regression network, the Hamming distance framework and likelihood estimation. The limitations of these methods are pointed out and resemblances that exist between them are underlined. Large-scale experiments carried out on StatLog project datasets confirm the n-tuple method as a viable competitor to more popular methods due to its speed, simplicity and accuracy on the majority of a wide variety of classification problems. A further investigation into the failure of the method on certain datasets shows its inner workings and reveals two main problems: difficulties with highly skewed class priors and more importantly, a mismatch between the scales involved in generalization, the amount of training data available, and the volume of the region in which data is likely to exist. This highlights areas where improvements in the method are needed and further theoretical progress would be helpful.

Journal Article↗
PubMed1999

An empirical evaluation of Bayesian sampling with hybrid Monte Carlo for training neural network classifiers.

This article gives a concise overview of Bayesian sampling for neural networks, and then presents an extensive evaluation on a set of various benchmark classification problems. The main objective is to study the sensitivity of this scheme to changes in the prior distribution of the parameters and hyperparameters, and to evaluate the efficiency of the so-called automatic relevance determination (ARD) method. The article concludes with a comparison of the achieved classification results with those obtained with (i) the evidence scheme and (ii) with non-Bayesian methods.

Journal Article↗
PubMedDate not supplied

Replication of certain recently classified viruses in Toxorhynchites amboinensis mosquitoes and in mosquito and mammalian cell lines, with implications for their arthropod-borne status.

Thirty-one viruses recently placed in taxa were studied for their replication in Toxorhynchites amboinensis by intrathoracic inoculation. Results were compared to those obtained in vitro in mammal and insect cell cultures. These findings provide presumptive evidence for the association of eighteen of these viruses with arthropod vectors.

Animals↗
PubMed2001

[Cerebellar vermis hypoplasia with extracerebral involvement (retina, kidney, liver): difficult to classify syndromes].

UNLABELLED: Congenital cerebellar vermis hypoplasias diversely associated with retinopathy, nephropathy and hepatopathy are rare syndromes of uncertain nosology. We report three new cases. CASE REPORTS: Case 1. A 3-month-old boy presented a brief nystagmus. At the age of 2 years, he had facial dysmorphia, hypotonia, ataxia, ocular motor apraxia and neurodevelopmental impairment with cerebellar vermis hypoplasia. The electroretinogram showed asymptomatic retinal involvement. At the age of 6 years, he developed chronic renal failure. The diagnosis of familial juvenile nephronophthisis was made by detection of a large homozygous deletion of the NPH1 region. Case 2. A term newborn boy presented apnea, tachypnea, hypotonia, nystagmus, ptosis, lack of visual contact and hepatomegaly. He had facial dysmorphia, bilateral optic coloboma with chorioretinal dysplasia and cerebellar vermis hypoplasia. There were cysts in the kidneys with increased echogenicity and lack of demarcation between the pyramids and the cortex. The liver was hyperechoic with fibrosis. At the age of 15 months, the child had severe developmental delay. He had bouts of fever. A search for a large homozygous deletion of the NPH1 region was negative. Case 3. A term newborn girl presented difficulty to suck, cyanosis, hypotonia and ptosis. Later, the child had a developmental delay. At the age of 6 years, she developed chronic renal failure (nephronophthisis). At the age of 23 years, she presented divergent strabismus, ataxia, mental retardation, slow ocular pursuit and facial dysmorphia. The neuroimaging showed a cerebellar vermis hypoplasia. A search for a large homozygous deletion of the NPH1 region was negative. CONCLUSION: The diagnosis of cerebellar vermis hypoplasia requires searching for retina, kidney and liver involvement. The large homozygous deletion of the NPH1 region has to be investigated if typical familial juvenile nephronophthisis is associated. Because cerebellar vermis hypoplasia with extracerebral involvements (retina, kidney, liver) is part of many different closely related syndromes, a clear molecular classification is necessary for accurate genetic counselling and an early prenatal diagnosis.

Abnormalities, Multiple↗
PubMed2002

An automatic microcalcification detection system based on a hybrid neural network classifier.

A hybrid intelligent system is presented for the identification of microcalcification clusters in digital mammograms. The proposed method is based on a three-step procedure: (a) preprocessing and segmentation, (b) regions of interest (ROI) specification, and (c) feature extraction and classification. The reduction of false positive cases is performed using an intelligent system containing two sub-systems: a rule-based and a neural network sub-system. In the first step of the classification schema 22 features are automatically computed which refer either to individual microcalcifications or to groups of them. Further reduction in the number of features is achieved through principal component analysis (PCA). The proposed methodology is tested using the Nijmegen and the Mammographic Image Analysis Society (MIAS) mammographic databases. Results are presented as the receiver operating characteristic (ROC) performance and are quantified by the area under the ROC curve (A(z)). In particular, the A(z) value for the Nijmegen dataset is 0.91 and for the MIAS is 0.92. The detection specificity of the two sets is 1.80 and 1.15 false positive clusters per image, at the sensitivity level higher than 0.90, respectively.

Automation↗
PubMed1993

Whole cell protein profiling of actinobacillus-like strains classified as taxon 2 and taxon 3 according to Bisgaard.

Thirty-nine strains representing all biovars established within the taxa 2 and 3 complex of Bisgaard and two strains belonging to the avian [P.] haemolytical[A.] salpingitidis complex were characterized by one-dimensional SDS-PAGE of cellular proteins. The protein patterns, which contained 40 to 45 discrete protein bands, were highly reproducible. Numerical analysis of the background protein patterns obtained resulted in six major and twelve minor groups (phena). Comparison of the phena defined by protein profiling with species/groups previously established by DNA: DNA hybridization, chemotyping and "biotyping" showed that the best correlation existed between DNA:DNA hybridization and "biotyping". A correlation between results obtained from DNA:DNA hybridization and protein profiling was not obtained. With a few exceptions, a connection was demonstrated between protein profiles and hosts from which the strains belonging to the respective phena originated.

Actinobacillus↗
PubMed1997

Further studies of the relationships among strains classified as taxon 15, taxon 18, taxon 20, (Pasteurella) granulomatis or the (Pasteurella) haemolytica-complex in ruminants using quantitative evaluation of phenotypic data.

Ninety-three trehalose-negative (P.) haemolytica-like strains of ruminant, porcine and leprine origin were investigated. A quantitative evaluation of phenotypic tests was used and the results obtained were compared with those from 246 previously investigated ruminant strains. Cluster analysis of the results obtained displayed most of the taxa as distinct groups which could be related to differences in key characters. Although only minor phenotypic differences were observed between the taxa investigated and the taxa were internally heterogeneous for many of the tests, it was possible to identify characters separating most groups. However, in three instances, taxa isolated from different species could not be separated by any of the tests used or by quantitative evaluation of all 79 tests--the only difference being the species of animals from which they had been isolated. Taxa which could not be separated by phenotypic tests included the ruminant biogroup 6 of (P.) haemolytica and the porcine taxon 15/biovar 1, the ruminant biogroup 7 of (P.) haemolytica and the porcine taxon 15/biovar 2, and ruminant biogroup 31 of (P.) haemolytica and the leprine taxon 20/biovar 1.

Animals↗