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At least 1,081 records · Page 60Linked to original sources
PubMed2005

Uncovering collective listening habits and music genres in bipartite networks.

In this paper, we analyze web-downloaded data on people sharing their music library, that we use as their individual musical signatures. The system is represented by a bipartite network, nodes being the music groups and the listeners. Music groups' audience size behaves like a power law, but the individual music library size is an exponential with deviations at small values. In order to extract structures from the network, we focus on correlation matrices, that we filter by removing the least correlated links. This percolation idea-based method reveals the emergence of social communities and music genres, that are visualized by a branching representation. Evidence of collective listening habits that do not fit the neat usual genres defined by the music industry indicates an alternative way of classifying listeners and music groups. The structure of the network is also studied by a more refined method, based upon a random walk exploration of its properties. Finally, a personal identification-community imitation model for growing bipartite networks is outlined, following Potts ingredients. Simulation results do reproduce quite well the empirical data.

Journal Article↗
PubMed1995

Inter-Company Collaboration Combination Trials. Clinical Trial Subcommittee of the Inter-Company Collaboration for AIDS Drug Development.

The Inter-Company Collaboration for AIDS Drug Development (ICC) represents a collaborative effort among member companies to facilitate the conduct of clinical trials on AIDS drugs. One of the goals of the ICC is to expedite the development of combination antiretroviral therapy through data and compound sharing. Recently, the ICC formed a consensus master protocol to evaluate rapidly the safety and efficacy of triple-drug combinations of antiretroviral therapy for treatment of HIV-infected patients. This concept builds upon historical work with combination chemotherapy that resulted in treatments to successfully control chronic immunosuppressive, infectious or malignant diseases, such as tuberculosis, leprosy, childhood acute lymphoblastic leukemia, and Hodgkin's lymphoma. Because of limitations on potency and the continuing emergence of drug resistance seen with use of currently available antiretroviral agents in monotherapy and two-drug combination regimens, triple-combination regimens should represent a more promising approach to maximize antiviral activity, maintain long-term efficacy, and reduce the incidence of drug resistance. The ICC master protocol is a randomized, controlled, double-blind study with a treatment duration of 52 weeks. Patients eligible to enroll in this study must have documented HIV infection, with CD4 counts between 200 and 500 cells/mm3, and no history of antiretroviral therapy. The first four triple-drug combinations will be evaluated in two trials. These regimens have been selected based on encouraging data from laboratory and clinical studies. Each ICC trial will consist of three arms, with 75 patients per arm. Protocol ICC 001 will include AZT + zalcitabine (ddC) + saquinavir, AZT + ddC + nevirapine, and AZT + ddC as the control arm.(ABSTRACT TRUNCATED AT 250 WORDS)

Antiviral Agents↗
PubMed1989

Determinants of needle sharing among intravenous drug users.

Data from 110 IV-drug abusing persons in methadone maintenance were analyzed to determine the correlates of needle sharing. Sharing was directly related to peer group behavior, attitudes conducive to sharing, economic motivation to share, not owning injection equipment, and fatalism about developing AIDS. Sharers were aware of their AIDS risk. Indicated measures to reduce needle sharing would be positive peer support groups to help resist pressures to share, legal and free access to fresh injection equipment, education on the utility of risk reduction, and increased treatment options for IV cocaine users.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Optimal self-cleavage activity of the hepatitis delta virus RNA is dependent on a homopurine base pair in the ribozyme core.

A non-Watson-Crick G.G interaction within the core region of the hepatitis delta virus (HDV) antigenomic ribozyme is required for optimal rates of self-cleavage activity. Base substitutions for either one or both G's revealed that full activity was obtained only when both G's were replaced with A's. At those positions, substitutions that generate potential Watson-Crick, G.U, heteropurine, or homopyrimidine combinations resulted in dramatically lower cleavage activity. A homopurine symmetric base pair, of the same type identified in the high-affinity binding site of the HIV RRE, is most consistent with this data. Additional features shared between the antigenomic ribozyme and the Rev binding site in the vicinity of the homopurine pairs suggest some structural similarity for this region of the two RNAs and a possible motif associated with this homopurine interaction. Evidence for a homopurine pair at the equivalent position in a modified form of the HDV genomic ribozyme was also found. With the postulated symmetric pairing scheme, large distortions in the nucleotide conformation, the sugar-phosphate backbone, or both would be necessary to accommodate this interaction at the end of a helix; we hypothesize that this distortion is critical to the structure of the active site of the ribozyme and it is stabilized by the homopurine base pair.

Base Composition↗
PubMed2004

PCR studies of feline leprosy cases.

16S rRNA gene sequence analysis provided evidence for two different mycobacterial species, Mycobacterium lepraemurium and a potentially novel species, as causative agents of 'feline leprosy'. Comparison of 16S rRNA gene sequence data obtained for M. lepraemurium and the potentially novel species indicated 12 nucleotide differences over a 446 bp region encompassing the V2 and V3 hypervariable regions. From available 16S rRNA gene sequence data, M. lepraemurium shared greatest nucleotide identity with M. avium subsp paratuberculosis and M. avium. The novel species had a long helix 18 in the V3 region and shared greatest nucleotide identity with M. leprae, M. haemophilum and M. malmoense. The novel species had an additional 'A' nucleotide at position 105 of the aligned 16S rRNA gene sequence, the only other mycobacterial database sequence having this same extra nucleotide being M. leprae. This nucleotide variation was exploited to develop specific PCR assays for the two species. These were found to be effective and specific when tested against a panel of mycobacteria including species found in feline leprosy lesions and closely related mycobacteria and also when applied directly to formalin-fixed, paraffin-embedded tissues from feline leprosy cases.

Animals↗
PubMed1991

Complete sequence of the allergen Amb alpha II. Recombinant expression and reactivity with T cells from ragweed allergic patients.

This study defines the complete primary structure of Amb alpha II, an important allergen produced by short ragweed (Ambrosia artemisiifolia). The deduced amino acid sequence derived from the cDNA indicates that Amb alpha II shares approximately 65% sequence identity with the Amb alpha I multigene family of allergens. Full-length cDNA encoding Amb alpha I.1 and Amb alpha II have been expressed in E. coli and purified. An in-frame linker encoding polyhistidine has been added to the 5' end of the cDNA to facilitate purification using Ni2+ ion affinity chromatography, yielding greater than 90% pure recombinant protein in a single step. T cells from patients allergic to ragweed proliferate in response to pollen extract as well as purified recombinant Amb alpha I.1 and Amb alpha II. T cell lines established using either Amb alpha I.1 or II as the stimulating Ag exhibit a high level of cross-reactivity to both proteins. This result is entirely consistent with the extensive primary sequence identity shared by these two proteins. These data suggest that allergic humans recognize shared T cell epitopes on these two related molecules.

Allergens↗
PubMed2002

Women's willingness to share information and participation in prenatal care systems.

With the expanded use of computerized databases to gather information, a concomitant interest in using databases for public health purposes has developed. The authors investigated correlates of consenting to participate in such databases. The Regional Perinatal Data System combines electronic birth certificate information with questions asked of all women delivering a livebirth. Each woman is asked to consent to share information with 1) her obstetric provider, 2) her infant's pediatric provider, and 3) an immunization registry. From 1996 to 1999, women who responded to the consent question and whose livebirth did not result in death or adoption were included. Odds ratios with 95% confidence intervals denoted the magnitude of association for refusing consent. Women who were "self-pay" (odds ratio = 2.0, 95% confidence interval: 1.7, 2.4), foreign born (odds ratio = 1.9, 95% confidence interval: 1.7, 2.1), and aged 40 or more years (odds ratio = 2.0, 95% confidence interval: 1.6, 2.3) were more likely to refuse to share data. Women eligible for but not participating in the Special Supplemental Nutrition Program for Women, Infants, and Children were significantly more likely to not share their information with others (odds ratio = 1.5, 95% confidence interval: 1.3, 1.6), after controlling for confounders. Refusing to share information with other sources is not random, and women refusing consent often do not participate in publicly available programs.

Access to Information↗
PubMed1993

Factors associated with heroin users' AIDS risk-taking behaviours.

A survey was undertaken in Sydney in 1989 to identify factors associated with behaviour involving risk for human immunodeficiency virus infection. Self-report data on needle-sharing and sexual practices were collected from 91 heroin users entering a residential, drug-free detoxification unit. Data were analysed using polytomous and ordinal logistic regressions. Heroin-dependent subjects who also had a current alcohol problem were significantly more likely than others to report high risk needle-sharing behaviour. Subjects with more than one sexual partner in the last three months were significantly more likely to use condoms while those with a current benzodiazepine problem were significantly less likely to use condoms. Qualitative data suggest that high risk needle-sharing behaviour most often occurred around the time of relapse to injecting drug use and among homeless drug users occupying derelict buildings in inner-city suburbs.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Shared calcium signaling pathways in the induction of long-term potentiation and synaptic disinhibition in CA1 pyramidal cell dendrites.

1. Calcium signaling pathways were examined in the induction of long-term synaptic disinhibition following tetanization. Effects of tetanization on gamma-aminobutyric acid-A (GABAA receptor-mediated inhibitory responses were measured and compared with excitatory responses under experimental conditions previously used for examining induction mechanisms of N-methyl-D-aspartate (NMDA)-dependent long-term potentiation (LTP). Intracellular recordings were performed in current-clamp and discontinuous single-electrode voltage-clamp (dSEVC) modes in CA1 pyramidal cell apical dendrites in hippocampal slices of adult guinea pigs with the use of sharp electrodes. Test pulses and tetanic stimuli were applied to the Schaffer collateral fibers in stratum radiatum. 2. Under standard control conditions [3 M K Ac in the recording pipette and artificial cerebrospinal fluid as extracellular solution], tetanization-induced sustained increases of excitatory responses were accompanied by marked decreases of parameters of GABAA-mediated synaptic inhibition: at 40 min after tetanization [posttetanus 40 (PT 40)], orthodromically evoked excitatory postsynaptic potential (EPSP) peak amplitudes were on average 195 +/- 15% (mean +/- SE) and excitatory postsynaptic currents (IPSPs) were 166 +/- 10% of pretetanus controls. Peak amplitudes of orthodromically evoked inhibitory postsynaptic potentials (IPSPs) were 30 +/- 5% and inhibitory postsynaptic currents (IPSCs) were 21 +/- 4% at PT 40. Synaptic GABAA conductances (measured as chord conductances) were reduced to 22 +/- 4% at PT 40. Iontophoretic GABAA responses measured as conductance changes were 28 +/- 4% of pretetanus controls at PT 40. 3. A role of NMDA receptors in induction of long-term synaptic disinhibition was tested by preventing NMDA receptor activation 1) by pharmacological means and 2) by holding the membrane clamped at -80 mV (in dSEVC) during tetanization. In the presence of the NMDA-receptor antagonist D-2-amino5-phosphonopentanoic acid (D-AP5) 10-40 microM), orthodromically evoked EPSP amplitudes were 107 +/- 9%, EPSCs were 104 +/- 6%, GABAA-mediated IPSPs were 88 +/- 8%, IPSCs were 97 +/- 8%, synaptic GABAA conductances were 84 +/- 9%, and iontophoretic GABAA conductances were 102 +/- 13% at PT 40. In recordings in which the dendritic membrane potential was clamped at -80 mV during tetanization, orthodromically evoked peak amplitudes of EPSPs were 105 +/- 11%, EPSCs were 102 +/- 8, IPSPs were 103 +/- 4%, IPSCs were 102 +/- 5%, GABAA chord conductances were 101 +/- 9%, and iontophoretically evoked GABAA conductances were 105 +/- 5% at PT 40. 4. In recordings in which the intracellular pipette was preloaded with the Ca2+ chelator 1,2-bis(2-aminophenoxy) ethane-N,N,N'N"-tetraacetic acid (BAPTA) (5mM), long-term changes of synaptic transmission (increases of excitation, decreases of synaptic inhibition) were prevented. At PT 40, EPSP peak amplitudes were 93 +/- 7%, EPSCs were 115 +/- 6%, IPSPs were 115 +/- 9%, IPSCs were 117 +/- 8%, and synaptic GABAA conductances were 108 +/- 17%. Iontophoretic conductances at PT 40 were 109 +/- 9% over pretetanus controls when recorded with BAPTA-containing electrodes. 5. In recordings in which the intracellular pipette was preloaded with cypermethrin, a potent and selective inhibitor of phosphatase 2B, respective long-term changes of synaptic transmission (increases of excitation, decreases of synaptic inhibition) were prevented. At PT 40, EPSP peak amplitudes were 98 +/- 6%, EPSCs were 105 +/- 10%, IPSPs were 99 +/- 5%, IPSCs were 104 +/- 7%, synaptic GABAA conductances were 97 +/- 6% and iontophoretic GABAA conductances were 113 +/- 18% over pretetanus controls in cypermethrin-containing recordings. 6. In conclusion, the data presented demonstrate shared cellular pathways in the induction of both LTP and long-term synaptic disinhibition in apical dendrites of CA1 pyramidal cells after tetanization of the Schaffer collaterals.

Animals↗
PubMed2003

Peripheral blood stem cell transplantation in children with beta-thalassemia major.

OBJECTIVE: To share the preliminary data on stem cell transplantation in Pakistan. DESIGN: This is a single center retrospective analysis of the outcome of allogeneic peripheral blood stem cell (PBSC) transplantation in b-thalassemia major patients. PLACE AND DURATION OF STUDY: Bismillah Taqee Blood Diseases Centre, Karachi; a tertiary care hematology center from September 1999 to September 2002. PATIENTS AND METHODS: Twelve patients with b-thalassemia major received allogeneic PBSC transplantation from HLA identical sibling donors except in one case where mother was the donor. All patients received busulphan and cyclophosphamide conditioning therapy and cyclosporin A/methotrexate for graft versus host disease (GVHD) prophylaxis. Donors were primed with G-CSF for 4 days and stem cells were harvested using Haemonetics MCS + cell separator on 5th day. All patients received G-CSF starting from day + 4 until their neutrophil count rose to normal. RESULTS: Engraftment was achieved in all patients except one who required a second dose of bone marrow graft on day +21. Median time to achieve absolute neutrophil count of > 0.5 x 10(9)/l was 9.0 days (range 8-31 days) and platelet count of > 20 x 10(9)/l was 14 days (12-35 days). Acute GVHD was seen in 3 patients, one patient had grade IV gut GVHD; another patient had grade III gut GVHD while third patient had grade II skin GVHD. Median hospital stay was 29 days. Six patients were well and transfusion independent 3 to 36 months posttransplant. One episode of primary graft failure required a second dose of bone marrow harvest. Another episode of graft rejection received two doses of donor lymphocytes infusion. There were 4 deaths due to grade IV gut GVHD because of uncontrolled systemic Candida infection and one due to hepatic veno-occlusive (VOD) disease. CONCLUSION: Allogeneic peripheral blood stem cell transplantation can be safely and economically carried out in Pakistan. Although there had been 4 deaths during 36 months follow-up, with increasing understanding and experience the outcome is expected to improve.

Child, Preschool↗
PubMedDate not supplied

Finding health resources on the Internet--the departure lounge.

As with all other areas of research, the influence of the Internet on health economics will continue to grow. The availability of information is central to the UK health reforms and plans are afoot to create an NHS network. Harnessing the power of the Net has become a basic research skill. This involves information and data capture, work sharing and communication as well as dissemination of our own work findings. You might optimistically regard the Internet as a system of arteries and arterioles through which oxygen of information may flow effectively to those who need it. However, users are sometimes frustrated by slow access, poorly indexed information and lots of noise: successful use sometimes seems reliant on serendipity. The Departure Lounge will try to keep you up to speed with developments.

Computer Communication Networks↗
PubMed2000

Proteomic analysis of laser capture microdissected human prostate cancer and in vitro prostate cell lines.

Specific populations of normal and malignant epithelium from three radical prostatectomy tissue specimens were procured by laser capture microdissection (LCM) and analyzed by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). Six proteins that were only seen in malignant cells and two proteins that were only seen in benign epithelium were reproducibly observed in two of two cases examined. Furthermore, these proteins were not observed in the 2-D PAGE profiles from the patient-matched microdissected stromal cell populations, but were seen in the protein profiles from the undissected whole cryostat sections. One of these proteins was determined to be prostate-specific antigen (PSA) by Western blot analysis, and intriguingly the remaining protein candidates were found to be at least as abundant as the PSA protein. Comparison of 2-D PAGE profiles of microdissected cell with matched in vitro cell lines from the same patient, and metastatic prostate cancer cell lines (LnCaP and PC3) showed striking differences between prostate cells in vivo and in vitro with less than 20% shared proteins. The data demonstrate that 2-D PAGE analysis of LCM-derived cells can reliably detect alterations in protein expression associated with prostate cancer, and that these differentially expressed proteins are produced in high enough levels which could allow for their clinical utility as new targets for therapeutic intervention, serum markers, and/or imaging markers.

Blotting, Western↗
PubMed2001

Multiple-threshold models for genetic influences on age of onset for Alzheimer disease: findings in Swedish twins.

Twin studies of dementia have typically used relatively simple 2 x 2 contingency tables with one threshold to estimate the relative importance of genetic variance for liability to disease. These designs are inadequate for addressing issues of age at onset, censoring of data, and distinguishing shared environmental effects from age effects. Meyer and Breitner [1998: Am J Med Genet 81:92-97] applied a multiple-threshold model to the NAS-NRC Twin Panel (average age of onset, 63.5 years) and report that additive genetic effects and shared environmental effects account for 37% and 35% of the variation, respectively, in age of onset for Alzheimer disease. We apply a modified version of their model to the Study of Dementia in Swedish Twins (average age of onset, 75 years) and find that genetic effects account for 57%-78% of the variance, whereas shared environmental effects are of no importance. Heritability is lower when thresholds are freely estimated rather than fixed to the population prevalences. We interpret the findings to suggest that models with free thresholds confound influences on longevity with influences for the disease. Multiple-threshold models, however, do not confound age effects with shared environmental influences.

Age of Onset↗
PubMed1995

HLA class II-restricted recognition of common tumor epitopes on human melanoma cells by CD4+ melanoma-infiltrating lymphocytes.

CD4+ T cell clones derived from lymphocytes infiltrating four human melanomas specifically recognized melanoma-derived tumor epitopes as shown by secretion of tumor necrosis factor (TNF) in vitro upon interaction with autologous melanoma cells, whereas they did not recognize HLA class II-expressing autologous lymphoblasts or HLA class II mismatched allogeneic melanoma cells. Specificity was further established by demonstrating that TNF responses to tumor cells were inhibited by HLA-DR or HLA-DQ monoclonal antibodies. Most of these clones cross-reacted with allogeneic melanoma cells expressing a potentially restricting HLA allele or a structurally similar one. These data show that shared epitopes of human melanoma cells presented on HLA class II molecules are frequently recognized by autologous CD4+ T lymphocytes.

Alleles↗
PubMed1993

Dose-dependent increase in subjective symptoms among toluene-exposed workers.

A factory survey on dose-response relationship in toluene toxicity was conducted in 1985-1989 in four cities in China. The examination items consisted of personal diffusive sampling for TWA exposure measurement, questionnaires on subjective symptoms, hematology and serum biochemistry, and clinical examination including simple neurology tests. Hippuric acid was also determined in urine samples collected at the end of the shift. With selection criteria that (1) complete results were available on all study items and (2) valid toluene exposure data (i.e., toluene shared 90% or more of the exposure) were obtained for the exposed, 452 toluene-exposed workers (206 men and 246 women; toluene exposure at 24.7 ppm as GM) and 517 nonexposed controls (246 men and 271 women) were selected. The subjective symptoms increased in close association with the intensity of exposure to toluene; the threshold concentration appeared to exist at 100 ppm in the case of symptoms during work, and it might be at 50-100 ppm when symptoms off work were evaluated. During the work with exposure at higher concentrations, various symptoms possibly related to CNS or local effects (e.g., eyes, nose, and throat) were complained, and dizziness and floating sensations were identified as typical symptoms with significant dose-response relationship. Several symptoms persisted off work, most of which were apparently related but not necessarily limited to CNS effects. Hematology and serum biochemistry were essentially negative.

Adolescent↗
PubMed1998

A gridded genomic library of the honeybee (Apis mellifera): a reference library system for basic and comparative genetic studies of a hymenopteran genome.

We present a gridded genomic library of the honey-bee (Apis mellifera) for comparative and basic genetic study of the honeybee genome. The library will be established as a "Reference Library" system, and clones as well as data will be shared with the entire scientific community. This will accelerate the molecular level of honeybee genetics, combining the efforts of different laboratories. Because of male haploidy and the high rate of recombination, the honeybee is becoming a model organism for genomic studies of naturally occurring traits and behavioral genetics. The library consists of about 110,000 clones spotted at high density onto four filter membranes, representing 22 genome equivalents. Preliminary analysis using single-copy sequences revealed a positive clone number of the same order. The techniques for library generation and preliminary analysis as well as library access are described.

Animals↗
PubMed1994

International harmonization for the risk assessment of pesticides: results of an IPCS survey.

Risk assessment harmonization has become an important issue on the environmental agendas of numerous countries. The benefits of an international consensus on risk assessment methodologies include decreased duplication of toxicity testing through the sharing of experimental data, decreased barriers to trade, and more consistency and cooperation within the scientific community. This paper presents the findings of an international survey of regulatory scientists in OECD and select non-OECD countries. The survey was sponsored by the International Programme on Chemical Safety (IPCS), which itself was formed by a cooperative agreement between the World Health Organization, the International Labor Organization, and the United Nations Environment Program. The survey results represent the first step in a project initiated by the IPCS to harmonize risk assessment methodologies used worldwide for the toxicological evaluation of chemicals. In this phase, the primary focus was on the health risk assessment of pesticides. Participants responded to questions regarding: (1) the support or review documents relied on for performing risk assessments; (2) procedures used and criteria applied when evaluating carcinogenicity data, including issues relating to mechanism of action, the maximum tolerated dose, and doses used in carcinogenicity bioassays; (3) risk assessment methodologies, such as the use no effect levels with safety factors or risk assessment models; (4) methods for assessing occupational and dietary exposure to pesticides; and (5) the primary areas of interest for the commencement of international harmonization efforts. There was significant consensus on specific issues relating to risk assessment methods and carcinogenicity assessment, as well as strong positive support for international harmonization activities. Differences existed with respect to the doses used in bioassays and data interpretation.

Animals↗
PubMed1992

Warm-up rates during arousal from torpor in heterothermic mammals: physiological correlates and a comparison with heterothermic insects.

This study examines the relationship between warm-up rate, body mass, metabolic rate, thermal conductance and normothermic body temperature in heterothermic mammals during arousal from torpor. Predictions based on the assumption that the energetic cost of arousal has been minimised are tested using data for 35 species. The observation that across-species warm-up rate correlates negatively with body mass is confirmed using a comparative technique which removes confounding effects due to the non-independence of species data due to shared common ancestry. Mean warm-up rate during arousal correlates negatively with basal metabolic rate and positively with the temperature difference through which the animal warms, having controlled for other factors. These results suggest that selection has operated to minimise the overall energetic cost of warm-up. In contrast, peak warm-up rate during arousal correlates positively with peak metabolic rate during arousal, and negatively with thermal conductance, when body mass has been taken into account. These results suggest that peak warm-up rate is more sensitive to the fundamental processes of heat generation and loss. Although heterothermic marsupials have lower normothermic body temperatures and basal metabolic rates, marsupials and heterothermic eutherian mammals do not differ systematically in warm-up rate. Pre-flight warm-up rates in one group of endothermic insects, the bees, are significantly higher than predictions based on rates of arousal of a mammal of the same body mass.

Animals↗