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At least 757 records · Page 42Linked to original sources
PubMed1994

Cytoskeletal organization of the vestibular sensory epithelia: saponin perfusion method for observing intracellular structures by scanning electron microscopy.

The cytoskeletal organization of the guinea pig vestibular sensory epithelial cells were investigated by the use of saponin perfusion method using scanning electron microscopy. The skeletal framework of a cell is composed of thin (actin or intermediate filaments) and thick filaments (microtubules). The membrane bound organelles such as nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, etc. were also well demonstrated. This made it possible to investigate the three-dimensional structures of cytoskeletons as well as their complex interactions with various membranes bound organelles. It is therefore suspected that this technique may provide us further information about distribution, topographic relationships, and the functional role of cytoskeletons.

Actin Cytoskeleton↗
PubMed2003

Electrical signaling in the olfactory bulb.

The olfactory bulb employs lateral and feedback inhibitory pathways to distribute odor information across parallel assemblies of mitral and granule cells. The pathways involve dendritic action potentials that can interact with a variety of voltage-dependent conductances and synaptic transmission to produce complex and dynamic patterns of activity. Electrical coupling also helps to ensure proper coordination and synchronization of these patterns. These mechanisms provide numerous options for dynamic modulation and control of signaling in the olfactory bulb.

Action Potentials↗
PubMed1997

Dissociation energetics and mechanisms of leucine enkephalin (M + H)+ and (2M + X)+ ions (X = H, Li, Na, K, and Rb) measured by blackbody infrared radiative dissociation.

The dissociation kinetics of protonated leucine enkephalin and its proton and alkali metal bound dimers were investigated by blackbody infrared radiative dissociation in a Fourier-transform mass spectrometer. From the temperature dependence of the unimolecular dissociation rate constants, Arrhenius activation parameters in the zero-pressure limit are obtained. Protonated leucine enkephalin dissociates to form b(4) and (M-H(2)O)(+) ions with an average activation energy (E(a)) of 1.1 eV and an A factor of 10(10.5) s(-1). The value of the A factor indicates that these dissociation processes are rearrangements. The b(4) ions subsequently dissociate to form a(4) ions via a process with a relatively high activation energy (1.3 eV), but one that is entropically favored. For the cationized dimers, the thermal stability decreases with increasing cation size, consistent with a simple electrostatic interaction in these noncovalent ion-molecule complexes. The E(a) and A factors are indistinguishable within experimental error with values of approximately 1.5 eV and 10(17) s(-1), respectively. Although not conclusive, results from master equation modeling indicate that all these BIRD processes, except for b(4) --> a(4), are in the rapid energy exchange limit. In this limit, the internal energy of the precursor ion population is given by a Boltzmann distribution and information about the energetics and dynamics of the reaction are obtained directly from the measured Arrhenius parameters.

Journal Article↗
PubMed2001

The shape of ears to come: dynamic coding of auditory space.

In order to pinpoint the location of a sound source, we make use of a variety of spatial cues that arise from the direction-dependent manner in which sounds interact with the head, torso and external ears. Accurate sound localization relies on the neural discrimination of tiny differences in the values of these cues and requires that the brain circuits involved be calibrated to the cues experienced by each individual. There is growing evidence that the capacity for recalibrating auditory localization continues well into adult life. Many details of how the brain represents auditory space and of how those representations are shaped by learning and experience remain elusive. However, it is becoming increasingly clear that the task of processing auditory spatial information is distributed over different regions of the brain, some working hierarchically, others independently and in parallel, and each apparently using different strategies for encoding sound source location.

Journal Article↗
PubMed2005

Effects of continuing medical education on improving physician clinical care and patient health: a review of systematic reviews.

OBJECTIVES: The objective of physician continuing medical education (CME) is to help them keep abreast of advances in patient care, to accept new more-beneficial care, and discontinue use of existing lower-benefit diagnostic and therapeutic interventions. The goal of this review was to examine effectiveness of current CME tools and techniques in changing physician clinical practices and improving patient health outcomes. METHODS: Results of published systematic reviews were examined to determine the spectrum from most- to least-effective CME techniques. We searched multiple databases, from 1 January 1984 to 30 October 2004, for English-language, peer-reviewed meta-analyses and other systematic reviews of CME programs that alter physician behavior and/or patient outcomes. RESULTS: Twenty-six reviews met inclusion criteria, that is, were either formal meta-analyses or other systematic reviews. Interactive techniques (audit/feedback, academic detailing/outreach, and reminders) are the most effective at simultaneously changing physician care and patient outcomes. Clinical practice guidelines and opinion leaders are less effective. Didactic presentations and distributing printed information only have little or no beneficial effect in changing physician practice. CONCLUSIONS: Even though the most-effective CME techniques have been proven, use of least-effective ones predominates. Such use of ineffective CME likely reduces patient care quality and raises costs for all, the worst of both worlds.

Clinical Competence↗
PubMed2006

Adequacy of antidote stocking in British Columbia hospitals: the 2005 Antidote Stocking Study.

BACKGROUND: Inadequate hospital stocking and the unavailability of essential antidotes is a worldwide problem with potentially disastrous repercussions for poisoned patients. Research indicates minimal progress has been made in the resolution of this issue in both urban and rural hospitals. In response to this issue the British Columbia Drug and Poison Information Centre developed provincial antidote stocking guidelines in 2003. We sought to determine the compliance with antidote stocking in BC hospitals and any factors associated with inadequate supply. METHODS: A 2-part survey, consisting of hospital demographics and antidote stocking information, was distributed in 2005 to all acute care hospital pharmacy directors in BC. The 32 antidotes examined (21 deemed essential) and the definitions of adequacy were based on the 2003 BC guidelines. Availability was reported as number of antidotes stocked per hospital and proportion of hospitals stocking each antidote. For secondary purposes, we assessed factors potentially associated with inadequate stocking. RESULTS: Surveys were completed for all 79 (100%) hospitals. A mean of 15.6+/-4.9 antidotes were adequately stocked per hospital. Over 90% of hospitals had adequate stocks of N-acetylcysteine, activated charcoal, naloxone, calcium salts, flumazenil and vitamin K; 71%-90% had adequate dextrose 50% in water (D50W), ethyl alcohol or fomepizole, polyethylene glycol electrolyte solution, protamine sulfate, and cyanide antidotes; 51%-70% had adequate folic acid, glucagon, methylene blue, atropine, pralidoxime, leucovorin, pyridoxine, and deferoxamine; and <50% had adequate isoproterenol and digoxin immune Fab. Only 7 (8.9%) hospitals sufficiently stocked all 21 essential antidotes. Factors predicting poor stocking included small hospital size (p < 0.0001), isolation (p = 0.01) and rural location (p < 0.0001). CONCLUSION: Although antidote stocking has improved since the implementation of the 2003 guidelines, essential antidotes are absent in many BC hospitals. Future research should focus on determining the reasons for this situation and the effects of corrective interventions.

Antidotes↗
PubMed2003

A method for assessing the statistical significance of mass spectrometry-based protein identifications using general scoring schemes.

This paper investigates the use of survival functions and expectation values to evaluate the results of protein identification experiments. These functions are standard statistical measures that can be used to reduce various protein identification scoring schemes to a common, easily interpretably representation. The relative merits of scoring systems were explored using this approach, as well as the effects of altering primary identification parameters. We would advocate the widespread use of these simple statistical measures to simplify and standardize the reporting of the confidence of protein identification results, allowing the users of different identification algorithms to compare their results in a straightforward and statistically significant manner. A method is described for measuring these distributions using information that is being discarded by most protein identification search engines, resulting in accurate survival functions that are specific to any combination of scoring algorithms, sequence databases, and mass spectra.

Mass Spectrometry↗
PubMed2006

Dynamics of the CH(A2Delta) product from the reaction of C2H with O2 studied by Fourier transform visible spectroscopy.

The reaction C(2)H + O(2) --> CH(A(2)Delta) + CO(2) is investigated using Fourier transform visible emission spectroscopy. C(2)H radicals, produced by 193 nm photolysis of C(2)H(2), react with O(2) molecules at low total pressures to produce electronically excited CH(A(2)Delta). Observation of the CH(A(2)Delta-X(2)Pi) electronic emission to infer nascent rotational and vibrational CH(A(2)Delta) distributions provides information about energy partitioning in the CH(A(2)Delta) fragment during the reaction. The rotational and vibrational populations of the CH(A(2)Delta) product are determined by fitting the rotationally resolved experimental spectra with simulated spectra. The CH(A(2)Delta) product is found to be rotationally and vibrationally excited with T(rot) congruent with 1150 K and T(vib) congruent with 1900 K. The mechanism for this reaction proceeds through one of two five-atom intermediates and requires a crossing between electronic potential surfaces. The rotational excitation suggests a bent geometry for the final intermediate of this reaction before dissociation to products, and the vibrational excitation involves an elongation of the C-H bond from the compressed transition state to the final CH(A) state.

Journal Article↗
PubMed2003

Peer education for HIV prevention in the Socialist Republic of Vietnam: a national assessment.

In 2000, the government of Vietnam conducted the first assessment of its national peer education program for HIV prevention. Twenty (32%) of Vietnam's 61 provinces and urban areas had functioning peer education programs, and program coordinators of all 20 were interviewed regarding their programs. In addition, on-site reviews were done for 10 of the 20 programs, including interviews of peer educators and high-risk persons in each program. The assessment found that a total of 500 peer educators were functioning either independently or as part of one of 79 teams. In the 20 provinces, the peer educators made an estimated 7,000 total contacts per month with high risk persons, but many persons were likely contacted repeatedly. Despite this, coverage was limited: some provinces with high numbers of persons reported with HIV/AIDS had few peer educators. Although most provinces targeted IDU and many targeted CSW, few provinces targeted sex partners of IDU or CSW. The definition of peer education and composition of teams varied substantially by province; only one province included persons living with HIV/AIDS as peer educators. The services provided by peer educators were primarily distributional: delivering information either through word of mouth, pamphlets, or brochures, providing condoms, and sometimes providing clean syringes and needles. Skills building or goal setting interventions aimed at HIV risk reduction were rarely provided. Most provinces had concerns about ongoing funding and sustainability of the programs. Based on the assessment, specific recommendations were provided for strengthening and expanding Vietnam's peer education programs.

Adolescent↗
PubMedDate not supplied

Psychological research online: report of Board of Scientific Affairs' Advisory Group on the Conduct of Research on the Internet.

As the Internet has changed communication, commerce, and the distribution of information, so too it is changing psychological research. Psychologists can observe new or rare phenomena online and can do research on traditional psychological topics more efficiently, enabling them to expand the scale and scope of their research. Yet these opportunities entail risk both to research quality and to human subjects. Internet research is inherently no more risky than traditional observational, survey, or experimental methods. Yet the risks and safeguards against them will differ from those characterizing traditional research and will themselves change over time. This article describes some benefits and challenges of conducting psychological research via the Internet and offers recommendations to both researchers and institutional review boards for dealing with them. ((c) 2004 APA, all rights reserved)

Advisory Committees↗
PubMed2004

Understanding customer reactions to brokered ultimatums: applying negotiation and justice theory.

There has been little research examining customer reactions to brokered ultimatum game (BUG) contexts (i.e. exchanges in which 1 party offers an ultimatum price for a resource through an intermediary, and the ultimatum offer is accepted or rejected by the other party). In this study, the authors incorporated rational decision-making theory and justice theory to examine how customers' bids, recommendations, and repatronage behavior are affected by characteristics of BUG contexts (changing from an ultimatum to negotiation transaction, response timeliness, and offer acceptance or rejection). Results indicated that customers attempt to be economically efficient with their bidding behavior. However, negotiation structures, long waits for a response, and rejected bids create injustice perceptions (particularly informational and distributive injustice), negatively influencing customers' recommendations to others and their repatronage. The authors then discuss the practical and theoretical implications of their results.

Adult↗
PubMed2000

The resonant dynamics of speech perception: interword integration and duration-dependent backward effects.

How do listeners integrate temporally distributed phonemic information into coherent representations of syllables and words? For example, increasing the silence interval between the words "gray chip" may result in the percept "great chip," whereas increasing the duration of fricative noise in "chip" may alter the percept to "great ship" (B. H. Repp, A. M. Liberman, T. Eccardt, & D. Pesetsky, 1978). The ARTWORD neural model quantitatively simulates such context-sensitive speech data. In ARTWORD, sequentially stored phonemic items in working memory provide bottom-up input to unitized list chunks that group together sequences of items of variable length. The list chunks compete with each other. The winning groupings feed back to establish a resonance which temporarily boosts the activation levels of selected items and chunks, thereby creating an emergent conscious percept whose properties match such data.

Cues↗
PubMed2001

The molecular dynamics of pain control.

Pain is necessary for survival, but persistent pain can result in anxiety, depression and a reduction in the quality of life. The discriminative and affective qualities of pain are both thought to be regulated in an activity-dependent fashion. Recent studies have identified cells and molecules that regulate pain sensitivity and the parallel pathways that distribute nociceptive information to limbic or sensory areas of the forebrain. Here, we emphasize the cellular and neurobiological consequences of pain, especially those that are involved in the generation and maintenance of chronic pain. These new insights into pain processing will significantly alter our approach to pain control and the development of new analgesics.

Animals↗
PubMed1988

The completeness of cancer registration in England: an assessment from the Oxford-FPA contraceptive study.

The completeness of cancer registration in England for the period 1968-85 has been assessed in a cohort of 17,000 women who reported malignancies directly to the investigators. Of 325 cancers reported, 281 (86.5%) had been registered by mid-1987. Under-registration varied considerably between regional cancer registries. Eight (18%) of the 44 unregistered cancers were treated in private hospitals. Under-registration also varied considerably with cancer site: only 8% of 150 breast cancers were not registered, and at sites accounting for 79% of all tumours, under-registration was less than 15%; however, 40% of melanomas (20 cases) and 50% of lung cancers (6 cases) were not registered. Of 281 registered tumours, only 219 (78%) were notified to the investigators from the NHSCR at Southport, with a median lag-time of 2.5 years since diagnosis. There has been a tendency for notification of registered cancers to the investigator to become more prompt but less complete.

Adult↗
PubMed2004

Experimental demonstration of five-photon entanglement and open-destination teleportation.

Quantum-mechanical entanglement of three or four particles has been achieved experimentally, and has been used to demonstrate the extreme contradiction between quantum mechanics and local realism. However, the realization of five-particle entanglement remains an experimental challenge. The ability to manipulate the entanglement of five or more particles is required for universal quantum error correction. Another key process in distributed quantum information processing, similar to encoding and decoding, is a teleportation protocol that we term 'open-destination' teleportation. An unknown quantum state of a single particle is teleported onto a superposition of N particles; at a later stage, this teleported state can be read out (for further applications) at any of the N particles, by a projection measurement on the remaining particles. Here we report a proof-of-principle demonstration of five-photon entanglement and open-destination teleportation (for N = 3). In the experiment, we use two entangled photon pairs to generate a four-photon entangled state, which is then combined with a single-photon state. Our experimental methods can be used for investigations of measurement-based quantum computation and multi-party quantum communication.

Journal Article↗
PubMed2001

Standardisation of multiplex fluorescent short tandem repeat analysis for chimerism testing.

To evaluate the origin of cells after allogeneic haematopoietic stem cell transplantation we optimised and evaluated two commercially available systems (AmpFlSTR Profiler Plus and GenePrint Powerplex-16) which are based on multiplex fluorescent short tandem repeat (STR) analysis. A standard procedure for interpretation of electropherographs was found essential to obtain reproducible results. On the basis of the relative length of donor and recipient alleles, TYPE-I (no shared alleles are used to calculate chimerism), TYPE-II (one shared and one unshared allele is used to calculate chimerism) or TYPE-III (not informative) allelic distribution types were distinguished. Also, stutter peaks were recognised as an important criterion to exclude a marker for analysis. Intralaboratory and multicentre evaluation of the AmpFlSTR Profiler Plus system showed that mixed blood samples could be determined with an absolute deviation of less than 2%. A sensitivity threshold was set at 5% for TYPE-I and 10% for TYPE-II markers since relative imprecision increases at low chimerism values. No significant difference of calculated chimerism values was observed between STR markers shared between both systems. By monitoring 26 allogeneic peripheral blood stem cell transplants, the applicability of the proposed method was demonstrated.

Alleles↗