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PubMedDate not supplied

Near-optimal region selection for feature space reduction: novel preprocessing methods for classifying MR spectra.

We introduce a global feature extraction method specifically designed to preprocess magnetic resonance spectra of biomedical origin. Such preprocessing is essential for the accurate and reliable classification of diseases or disease stages manifest in the spectra. The new method is genetic algorithm-guided. It is compared with our enhanced version of the standard forward selection algorithm. Both seek and select optimal spectral subregions. These subregions necessarily retain spectral information, thus aiding the eventual identification of the biochemistry of disease presence and progression. The power of the methods is demonstrated on two biomedical examples: the discrimination between meningioma and astrocytoma in brain tissue biopsies, and the classification of colorectal biopsies into normal and tumour classes. Both preprocessing methods lead to classification accuracies over 97% for the two examples.

Algorithms↗

PubMed2001

Effect of genotype on selected clinical features of Polish cystic fibrosis adults.

UNLABELLED: Cystic fibrosis (CF), the most common autosomal recessive disorder of Caucasians, is caused by the mutations in the gene encoding CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) protein. Until now, approximately 1000 mutations of the CFTR gene have been described. The genotype-phenotype relationships in CF are still not completely understood. This study was undertaken in an attempt to characterise the distribution of CFTR mutations and their effect on selected clinical parameters in a group of Polish CF adults. A total number of 38 adult CF patients (mean age 21.6 +/- 6.8); 18 females & 20 males were enrolled in the study. The CFTR gene identification was conducted with the use of PCR & InnoLipa-CF set. The assessed clinical parameters included: age at diagnosis, age, lung function test, X-ray scored in Brasfield score, weight & height. We found that: (1) the genotypes of the studied population were unevenly distributed (65.8%- genotype deltaF508/M), (2) a high percentage of 3849+10kbC-->T was noted, (3) patients homozygous for the deltaF508 mutation were diagnosed significantly earlier and had a lower body mass index, (4) no differences were observed in the patients' length of life or the progression of lung disease. CONCLUSIONS: 1. In comparison to other populations, Polish adult CF patients display a relatively higher frequency of mild mutations. 2. Late diagnosis of CF in the studied group may be partially caused by a high percentage of CFTR mutations connected with the mild course of the disease that are difficult to identify. 3. Cystic fibrosis should be more commonly taken into consideration in the differential diagnosis in adult patients with milder symptoms.

Journal Article↗

PubMed2005

HIV in female sex workers in five border provinces of Vietnam.

OBJECTIVES: To determine the prevalence of HIV and associated risk factors among female sex workers (FSWs) in border provinces of Vietnam. METHODS: 911 FSWs in five border provinces of Vietnam (Lai Chau, Quang Tri, Dong Thap, An Giang, and Kien Giang) were enrolled in a cross sectional study. Subjects were interviewed using a standardised questionnaire about selected sociodemographic and behavioural characteristics, history of STIs, and information about their cohabiting partners (husbands or live-in partners). Serological tests were done for HIV and syphilis (TPHA+RPR) and urine tests (PCR) for chlamydia and gonorrhoea. Associations between HIV and selected features of FSWs and their partners were examined using univariate and multivariate logistic regression analysis. RESULTS: Overall, the prevalence of HIV among FSWs in the five provinces of Vietnam was 4.5%. The prevalence of HIV was higher in the southern border regions (4.0%-7.0%) than the northern (2%) and central (1%) regions. In multivariate analysis between HIV and selected features of FSWs, income < or =$33/month (OR 2.36, p = 0.04), age of first sex < or =15 (OR = 5.48, p = 0.005), and > or =9 clients per week (OR 2.80, p = 0.018) were associated with HIV infection. Positive syphilis serology achieved a borderline significant association with HIV (OR 2.30, p = 0.095). Having a regular non-paying partner (OR = 0.35, p = 0.060) was a borderline protective factor for HIV. CONCLUSION: Interventions to limit HIV transmission among FSWs in Vietnam should be implemented early and focus on young poor populations in these border areas.

Adolescent↗

PubMed2006

Convergent, enantioselective syntheses of guanacastepenes A and E featuring a selective cyclobutane fragmentation.

The evolution of a convergent strategy that led to efficient, enantioselective syntheses of both natural (+)- and unnatural (-)-guanacastepene E and formal total syntheses of (+)- and (-)-guanacastepene A is described. A union of five- and six-membered ring intermediates by an efficient pi-allyl Stille cross-coupling reaction was followed by an intramolecular enone-olefin [2 + 2] photocycloaddition and a stereoelectronically controlled, reductive fragmentation of the resulting cyclobutyl ketone. The latter two transformations enabled controlled formation of the C-11 quaternary stereocenter and the central seven-membered ring of the guanacastepenes. An enantiospecific synthesis of the functionalized five-membered ring vinyl stannane from the monoterpene R-(-)-carvone featuring a carbon-carbon bond forming ring contraction was also developed.

Chemistry, Organic↗

PubMed2005

Background-activity-dependent properties of a network model for working memory that incorporates cellular bistability.

In models of working memory, transient stimuli are encoded by feature-selective persistent neural activity. Network models of working memory are also implicitly bistable. In the absence of a brief stimulus, only spontaneous, low-level, and presumably nonpatterned neural activity is seen. In many working-memory models, local recurrent excitation combined with long-range inhibition (Mexican hat coupling) can result in a network-induced, spatially localized persistent activity or "bump state" that coexists with a stable uniform state. There is now renewed interest in the concept that individual neurons might have some intrinsic ability to sustain persistent activity without recurrent network interactions. A recent visuospatial working-memory model (Camperi and Wang 1998) incorporates both intrinsic bistability of individual neurons within a firing rate network model and a single population of neurons on a ring with lateral inhibitory coupling. We have explored this model in more detail and have characterized the response properties with changes in background synaptic input I(o) and stimulus width. We find that only a small range of I(o) yields a working-memory-like coexistence of bump and uniform solutions that are both stable. There is a rather larger range where only the bump solution is stable that might correspond instead to a feature-selective long-term memory. Such a network therefore requires careful tuning to exhibit working-memory-like function. Interestingly, where bumps and uniform stable states coexist, we find a continuous family of stable bumps representing stimulus width. Thus, in the range of parameters corresponding to working memory, the model is capable of capturing a two-parameter family of stimulus features including both orientation and width.

Action Potentials↗

PubMed2005

Block of peripheral nerve sodium channels selectively inhibits features of neuropathic pain in rats.

Several sodium channel blockers are used clinically to treat neuropathic pain. However, many patients fail to achieve adequate pain relief from these highly brain-penetrant drugs because of dose-limiting central nervous system side effects. Here, we describe the functional properties of trans-N-{[2'-(aminosulfonyl)biphenyl-4-yl]methyl}-N-methyl-N'-[4-(trifluoromethoxy)benzyl]cyclopentane-1,2-dicarboxamide (CDA54), a peripherally acting sodium channel blocker. In whole-cell electrophysiological assays, CDA54 blocked the inactivated states of hNa(V)1.7 and hNa(V)1.8, two channels of the peripheral nervous system implicated in nociceptive transmission, with affinities of 0.25 and 0.18 microM, respectively. CDA54 displayed similar affinities for the tetrodotoxin-resistant Na+ current in small-diameter mouse dorsal root ganglion neurons. Peripheral nerve injury causes spontaneous electrical activity in normally silent sensory neurons. CDA54 inhibited these injury-induced spontaneous action potentials at concentrations 10-fold lower than those required to block normal A- and C-fiber conduction. Consistent with the selective inhibition of injury-induced firing, CDA54 (10 mg/kg p.o.) significantly reduced behavioral signs of neuropathic pain in two nerve injury models, whereas the same dose of CDA54 did not affect acute nociception or motor coordination. In anesthetized dogs, CDA54, at plasma concentrations of 6.7 microM, had no effect on cardiac electrophysiological parameters including conduction. Thus, the peripheral nerve sodium channel blocker CDA54 selectively inhibits sensory nerve signaling associated with neuropathic pain.

Administration, Oral↗

PubMed1984

Selected acoustic features of tracheoesophageal, esophageal, and laryngeal speech.

Voice samples of 15 laryngeal, esophageal, and tracheoesophageal speakers using the Blom-Singer voice prosthesis were analyzed for intensity, frequency, and rate. Results indicate that characteristic values for tracheoesophageal speech are more similar to laryngeal speech than esophageal speech, demonstrating the powerful advantage of this pulmonary-supported method of alaryngeal voice.

Acoustics↗

PubMed2001

Feature (gene) selection in gene expression-based tumor classification.

There is increasing interest in changing the emphasis of tumor classification from morphologic to molecular. Gene expression profiles may offer more information than morphology and provide an alternative to morphology-based tumor classification systems. Gene selection involves a search for gene subsets that are able to discriminate tumor tissue from normal tissue, and may have either clear biological interpretation or some implication in the molecular mechanism of the tumorigenesis. Gene selection is a fundamental issue in gene expression-based tumor classification. In the formation of a discriminant rule, the number of genes is large relative to the number of tissue samples. Too many genes can harm the performance of the tumor classification system and increase the cost as well. In this report, we discuss criteria and illustrate techniques for reducing the number of genes and selecting an optimal (or near optimal) subset of genes from an initial set of genes for tumor classification. The practical advantages of gene selection over other methods of reducing the dimensionality (e.g., principal components), include its simplicity, future cost savings, and higher likelihood of being adopted in a clinical setting. We analyze the expression profiles of 2000 genes in 22 normal and 40 colon tumor tissues, 5776 sequences in 14 human mammary epithelial cells and 13 breast tumors, and 6817 genes in 47 acute lymphoblastic leukemia and 25 acute myeloid leukemia samples. Through these three examples, we show that using 2 or 3 genes can achieve more than 90% accuracy of classification. This result implies that after initial investigation of tumor classification using microarrays, a small number of selected genes may be used as biomarkers for tumor classification, or may have some relevance in tumor development and serve as a potential drug target. In this report we also show that stepwise Fisher's linear discriminant function is a practicable method for gene expression-based tumor classification.

Humans↗

PubMed1981

Structural features and selective expression of three Ly-5+ cell-surface molecules.

Conventional Ly-5 alloantisera precipitate cell-surface molecules of three sizes: 200K, 205K, and 220K. In SDS-PAGE, the rat monoclonal antibody 74/8' precipitates the same three molecules from both Ly-5.1 and Ly-5.2 cells. Cleveland mapping of the three molecules, precipitated by reaction of conventional Ly-5 alloantisera or 74/8' monoclonal antibody with lysates of 125I-labeled cells, disclosed no differences among the three molecular forms, but markedly distinguished all three Ly-5.1 molecules from all three Ly-5.2 molecules. Each of the three molecular forms can be expressed independently of the other two by cloned culture lines of Ly-5+ cells of different hematopoietic lineage. All of the seven cloned lines tested expressed only one form. However, two of the seven uncloned culture lines tested, plasmacytoma MOPC-70A and the X.1 putative macrophage line which originated from an SJL tumor, yielded both 200K and 205K forms.

Animals↗

PubMed1989

Selected pragmatic features in Spanish-speaking preschool children.

We assessed Spanish-speaking preschool children for the development of seven language functions and three discourse features. Analyses consisted of spontaneous language samples averaging 136 utterances per child, for 18 subjects between 3:0 and 4:5 (years:months). Data for the frequency of occurrence and the percentage of appropriate usage showed that the preschoolers had established communicative competence for the functions and discourse features. Implications include establishing preliminary guidelines for the development of normal pragmatics in Hispanic preschoolers. We also discuss the 10-item taxonomy as a reliable and clinically useful tool with either English-speaking or Spanish-speaking children.

Central America↗

PubMed2005

Microcalcifications associated with breast cancer: an epiphenomenon or biologically significant feature of selected tumors?

Radiographic mammary calcifications occur in 30-50% of breast cancers and constitute one of the most important diagnostic markers of both benign and malignant lesions of the breast. The presence of oxalate-type microcalcification appears to be a reliable criterion in favor of the benign nature of the lesion or, at most, of a lobular carcinoma in situ. In contrast, calcium hydroxyapatite (HA) crystals are associated with both benign and malignant breast tumors. Although the diagnostic value of microcalcifications in breast cancer is of great importance, the genesis of these calcifications is unclear. Despite numerous histological ultrastructure studies of HA deposits in breast carcinomas, to date there have been limited investigations of the potential role of these crystals in breast cancer. We review the literature examining the biological effects of HA crystals in breast cancer cell lines, specifically the mechanism of HA-induced mitogenesis and upregulation of gene expression.

Breast↗

PubMed1990

Respiratory infections caused by Branhamella catarrhalis. Selected epidemiologic features.

PURPOSE: This work reviewed existing literature pertaining to the epidemiologic aspects of respiratory tract infections caused by Branhamella catarrhalis, examined certain epidemiologic features of B. catarrhalis infections occurring at this facility, and identified relevant areas in need of further study. PATIENTS AND METHODS: Literature dealing with the epidemiology of B. catarrhalis infections was reviewed. Records in this Veterans Administration hospital microbiology laboratory were reviewed and all B. catarrhalis isolates and pure cultures of Hemophilus influenzae and Streptococcus pneumoniae were noted for the January 1986 to June 1989 study period. RESULTS: B. catarrhalis is now recognized as a disease-causing pathogen that is particularly noted for its association with acute otitis media in children and lower respiratory tract infections in adults with underlying cardiopulmonary disease. It was recovered from 2.7 percent of all respiratory specimens submitted over a 42-month period at this Veterans hospital. When compared with H. influenzae and S. pneumoniae, B. catarrhalis was found to be the second most commonly isolated respiratory pathogen. It was frequently found in pure culture (53 percent) or in combination with H. influenzae, gram-negative bacilli, or S. pneumoniae. The seasonal recovery of B. catarrhalis was apparent for the November to May period compared with the June to October period (p less than 0.001). CONCLUSION: B. catarrhalis has emerged as a major respiratory pathogen in pediatric and adult patient populations. There is a distinct seasonal pattern associated with its recovery and reasons for this are unclear. Prevalence studies aimed at identifying colonization rates among "low" and "high" risk groups are needed. The availability of restriction endonuclease analysis as a typing system for B. catarrhalis should favorably impact upon future epidemiologic studies. Many B. catarrhalis isolates produce beta-lactamase, and therapeutic options must reflect this.

Adult↗

PubMed1994

Background EEG activity in preterm infants: correlation of outcome with selected maturational features.

The aim of this study is to identify normal EEG patterns of preterm infants, characteristic of early postmenstrual ages (PMAs). Quantitative features of EEG background activity have been examined in records from 83 preterm infants within the first 2 weeks of life at a PMA of 27-34 weeks. These subjects presented different cranial ultrasound findings and different outcomes. EEG quantitative data have been compared to the subsequent neurological evolution. We supposed that the features of EEG background activity which were associated with a favourable outcome should be considered as indexes of "normality" of the tracing for that specific PMA. At 27-30 weeks of PMA a high incidence of "temporal sawtooth," a particular rhythmic theta activity detectable in temporal regions, relates to a favourable evolution, therefore it can be assumed that this activity is a normal feature of EEG tracings at this age. On the contrary, a significant correlation between a high incidence of "temporal sawtooth" and an abnormal outcome is observable at 33-34 weeks and leads us to deduce that this pattern should disappear at this time. After 31 weeks other parameters (such as the incidence of 8-20 Hz activities, the length of the intervals and burst duration) show a significant correlation with the outcome.

Brain↗

PubMed1983

Selected organizational features of certain Polish health care institutions.

A special feature of the Polish health care system in the 70s was the process toward organizational centralization. This consisted in integrating independent organizational units into larger, more complex ones, and transferring the processes of decision-making to higher management levels. This transition was introduced in 1975. One of its effects was incorporating into one organization all health care systems in a given area, primary care hospitals, specialist care units, laboratory bases, emergency and social welfare agencies and subsuming all these institutions under one management. The ensuing organization was named the Health Care Complex (HCC). It is interesting that in the HCC area other organizations were founded to cover industrial workers. These were called Occupational Health Care Complexes (OHCC). This paper deals with a description of a variety of OHCC organizational structures, an analysis of the relationships between different parameters of organizational structures (leaving aside, however, their casual interpretation), and an examination of the possibilities for applying empirical data to OHCC organizational structural analysis.

Humans↗

PubMed1998

The association of selected pathological features with prostate cancer in a single-needle biopsy accession.

Isolated high-grade prostatic intraepithelial neoplasia (PIN) has been shown to be a positive predictor of prostate cancer (PCa) on follow-up biopsy. However, the incidence of isolated high-grade PIN in needle biopsy specimens has been reported with a highly variable frequency of 1% to 15%. The current study examined the relationship of various pathological features with PCa on a single biopsy accession. A study population of 388 community-based consecutive needle biopsy accessions was prospectively recorded by a single pathologist (T.M.W.). All of the individual biopsy specimens were coded for the presence of PCa, high-grade PIN, low-grade PIN, chronic inflammation (CI), intraluminal prostatic crystalloids (IPC) in benign glands, and mucinous metaplasia (MM). One hundred twenty-nine (33%) of the patients were diagnosed with PCa. The 8% incidence of isolated high-grade PIN was consistent with previous studies. The incidence of other pathological features were as follows: high-grade PIN, 14%; low-grade PIN, 13%; CI, 30%; IPC, 4%; and MM, 8%. Of the patients with high-grade PIN, 47% had PCa on a separate core biopsy, whereas 31% of patients without high-grade PIN were observed to have PCa (P=.021). Of the patients with CI, 21% were found to have PCa on a separate core, whereas 38% of patients without CI were found to have PCa (P=.0009). None of the other pathological features surveyed showed any significant association with PCa. High-grade PIN was a relatively common finding (14%) in this study and was positively associated with PCa on a separate core from the same accession biopsy. The negative association of CP with PCa within the same accession has not been reported previously and may be an artifact related to the clinical indications for a prostatic biopsy.

Adenocarcinoma↗

PubMed1996

Apoptotic features of selective neuronal death in ischemia, epilepsy and gp 120 toxicity.

The occurrence of physiological cell death has been known for decades, but interest in the subject was renewed in 1972 when Kerr, Wyllie and Currie described in detail the ultrastructural changes characteristic of dying cells and coined the term apoptosis to describe the process. Cells display a wide variety of morphological changes when dying during development or following a toxic insult. A binary classification scheme suggests that physiologically appropriate death is due to apoptosis and that pathological mechanisms involve necrosis. However, recent studies indicate a potential involvement of apoptotic cell death in ischemia, status epilepticus and HIV-1 infection.

Animals↗

PubMed1994

Differentiation of selected members of the family Neisseriaceae (Alysiella, Eikenella, Kingella, Simonsiella and CDC groups EF-4 and M-5) by carbohydrate fingerprints and selected phenotypic features.

On the basis of nucleic acid relationships, the family Neisseriaceae consists of the genera Neisseria, Kingella, Simonsiella and of Alysiella filiformis, Eikenella corrodens, and the CDC groups EF-4 and M-5. Differentiation, especially of the new members of the family, by conventional phenotypic characteristics is difficult and in some cases leads to doubtful results. On the other hand, cellular components proved to be suitable for the characterization of bacterial taxa. We investigated the cellular carbohydrates derived from whole cell hydrolysates of the above mentioned taxa with the exception of Neisseria by gas chromatography/mass-spectrometry. The analysis revealed characteristic patterns for all taxa considered, although with some species of which only few strains were investigated so far only preliminary results could be established. With the method used, the carbohydrate analysis could be completed within six hours starting from a pure culture. All strains investigated exhibited a common pattern with ribose, arabinose, glucose, and galactose. Qualitative and quantitative differences in contents of fucose, sorbose, rhamnose, threose, heptose, galactosamine and an amino sugar similar to glucosamine discriminated members of the taxa investigated. To achieve a taxonomically precise differentiation of the species investigated by conventional phenotypic features as available in commercial rapid test kits, these tests should be completed by the carbohydrate analysis technique presented.

Carbohydrates↗

PubMed2000

Neonicotinoid insecticides: molecular features conferring selectivity for insect versus mammalian nicotinic receptors.

The favorable selective toxicity of neonicotinoid insecticides (represented here by imidacloprid, thiacloprid, and a nitromethylene analogue) for insects versus mammals is not shared by three of their N-unsubstituted imine derivatives or by nicotine or epibatidine. The same selectivity pattern is evident at the receptor level, i.e., the insect nicotinic acetylcholine receptor (nAChR) versus mammalian nAChR subtypes (alpha1, alpha3, alpha4, and alpha7) assayed independently. The insect-selective compounds are not protonated with a nitroimine, cyanoimine, or nitromethylene group and the mammalian-selective compounds are ionized at physiological pH. We propose that the negatively charged tip of the nitro or cyano group (not a partial positive charge at imidazolidine N-1 as suggested earlier) interacts with a putative cationic subsite of the insect nAChR. This contrasts with the mammalian nAChRs where the iminium cation (+C-NH2 <--> C =+NH2) of the neonicotinoid imine derivatives or ammonium nitrogen of nicotine or epibatidine interacts with the anionic subsite.

Animals↗