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Biomedical subjects

D Gammon

Publications and source records attributed to D Gammon.

At least 37 records · Page 2Linked to original sources
PubMed1999

Characterization of maternal influence on teratogenicity: an assessment of developmental toxicity studies for the herbicide cyanazine.

The contribution of maternal toxicity to the teratogenic effects of the herbicide cyanazine has been assessed to determine whether it may be a hazard to development. Eye defects such as anophthalmia and microphthalmia were observed in rat fetuses and pups. Maternal toxicity was determined from body weight data and clinical signs. Two approaches were used. First, the timing of maternal toxicity was correlated with the specific period of gestation during which the observed fetal defect was most likely to have occurred. Second, individual dams, as well as mean values for each group, were evaluated. The data at the individual level, i.e., in dams with affected litters, did not support conclusions based on the group means. Instead, it is suggested that the developmental effects were not a direct result of maternal toxicity of cyanazine. Data from a rabbit developmental toxicity study supported the findings from the Fischer 344 rat studies. The strategy employed may thus enable direct toxicity to the fetus to be distinguished from developmental toxicity arising as a secondary consequence of maternal toxicity.

Abnormalities, Drug-Induced↗
PubMed1998

Coherent optical control of the quantum state of a single quantum Dot

Picosecond optical excitation was used to coherently control the excitation in a single quantum dot on a time scale that is short compared with the time scale for loss of quantum coherence. The excitonic wave function was manipulated by controlling the optical phase of the two-pulse sequence through timing and polarization. Wave function engineering techniques, developed in atomic and molecular systems, were used to monitor and control a nonstationary quantum mechanical state composed of a superposition of eigenstates. The results extend the concept of coherent control in semiconductors to the limit of a single quantum system in a zero-dimensional quantum dot.

Journal Article↗
PubMed1998

CTL response to Mycobacterium tuberculosis: identification of an immunogenic epitope in the 19-kDa lipoprotein.

The successful resolution of infection with Mycobacterium tuberculosis (M.tb) is believed to involve the induction of CTLs that are capable of killing cells harboring this pathogen, although little information is known about the MHC restriction or fine specificity of such CTLs. In this study, we used knowledge of the HLA-A*0201-binding motif and an immunofluorescence-based peptide-binding assay to screen for potential HLA-A*0201-binding epitopes contained in the 19-kDa lipoprotein of M.tb (M.tb19). CD8+ T cells derived from HLA-A*0201+ patients with active tuberculosis (TB) as well as tuberculin skin test-positive individuals who had no history of TB were used as effector cells to determine whether these epitopes are recognized by in vivo-primed CTLs. An in vitro vaccination system using HLA-A*0201+ dendritic cells (DCs) as APCs was used to determine whether these epitopes can sensitize naive CD8+ T cells in vitro, leading to the generation of Ag-specific CTLs. The results show that an HLA-A*0201-binding peptide comprised of residues 88 to 97 of M.tb19 (P88-97) is recognized by circulating CD8+ CTLs from both healthy tuberculin skin test-positive individuals and patients with active TB but not by tuberculin skin test-negative subjects. Moreover, dendritic cells pulsed with this peptide induced class I MHC-restricted CTLs from the T cells of healthy unsensitized persons. Finally, CTL lines that were specific for P88-97 were shown to lyse autologous monocytes that had been infected acutely with the H37Ra strain of M.tb. These results demonstrate that M.tb19 elicits HLA class I-restricted CTLs in vitro and in vivo that recognize endogenously processed Ag. Epitopes of the type identified here may prove useful in the design of an M.tb vaccine.

Alleles↗
PubMed1998

Optical NMR from single quantum dots.

Nuclear magnetic resonance (NMR) from constituent Ga and As nuclei was optically detected on excitonic recombination in single GaAs quantum dots formed by interface fluctuations in GaAs/Al0.3Ga0.7As quantum wells. Orientation of the nuclear spin system by optical pumping causes an Overhauser shift of the excitonic energy levels proportional to the degree of nuclear orientation. NMR was subsequently detected by monitoring changes in the combined Overhauser plus Zeeman splitting of excitons localized in single quantum dots as the RF frequency was swept through a nuclear resonance. The NMR signals originate from approximately 10(5) nuclei in the quantum dot-with dimensions of approximately 4 nm X 10 nm X 100 nm--illustrating the extreme sensitivity and spatial resolution of the technique. NMR from such small structures provides a chemically specific probe of the local environment on the nanometer scale.

Arsenicals↗
PubMed1998

Psychotherapy supervision conducted by videoconferencing: a qualitative study of users' experiences.

Psychiatry residents in Norway have 70 hours of mandatory psychotherapy supervision to develop insights into the therapeutic relationship. Six supervision pairs (six candidates and two supervisors) conducted five videoconferencing-based supervision sessions (384 kbit/s) and five face-to-face sessions alternating weekly for 10 sessions. Following completion of the 10 sessions for candidates and supervisor B, and the 50 sessions for supervisor A, all subjects completed a semi-structured interview within two weeks. The eight subjects reported a wide range of experiences and attitudes. The results suggested that the quality of supervision can be satisfactorily maintained by using videoconferencing for up to half of the 70 hours required. The precondition for this estimate is that the pair in question have met face to face and established a relationship characterized by mutual trust and respect. Further studies, which include supervision pairs not having previously established relationships, are needed in order to indicate the generality of this precondition. The most obvious implication of this study is the potential for implementing decentralized models for recruiting and educating psychiatrists.

Adult↗
PubMed1997

Mycobacterium avium reduces expression of costimulatory/adhesion molecules by human monocytes.

Organisms of the Mycobacterium avium complex survive the hostile environment of their host cells, the macrophages, and evade immune response, in part, by interfering with processing and presentation of antigen. We studied the effect of infection with M. avium on the expression of the costimulatory/adhesion molecules (referred to herein as accessory molecules) because generating an efficient T cell response requires both the recognition of processed antigen and the participation of accessory molecules. Human peripheral blood monocytes displayed reduced levels of CD54, CD58, and CD86 molecules 1 day after in vitro infection. The reduction in the expression of accessory molecules was not mediated by endogenous IL-10 or prostaglandin because monocytes infected in the presence of either anti-IL-10 neutralizing antibody or indomethacin did not express normal levels of surface CD54, CD58, and CD86 molecules. Consistent with these phenotypic changes, M. avium-infected monocytes were less effective in supporting Ag-independent proliferation of autologous CD4+ T cells.

Antigens, CD↗
PubMed1997

Video conferencing in group training of psychiatric nurses.

Video conferencing (VC) technology transfers synchronous audio and video signals via standard telecommunication lines. VC has become a useful communication device in the mental health care sector in Norway, particularly in the northern countries. Training and supervision is considered one of the areas where VC has great potential. This study followed a group of nurses who used VC in a training program every other week over a period of six months. The group consisted of seven nurses (two supervisors and five supervisees). Data was collected from four of the VC sessions. User satisfaction and judgements on the effect of VC on critical aspects of the supervision were evaluated through questionnaires. In addition, a closing group interview was held to sum up qualitative experiences and attitudes. Results indicate that VC may indeed be an acceptable tool in group supervision. Participants reported that they were able to establish a climate for communicating on an emotional and personal level, as well as provide necessary feedback and psychological support.

Female↗
PubMed1996

Homogeneous Linewidths in the Optical Spectrum of a Single Gallium Arsenide Quantum Dot

The homogeneous linewidths in the photoluminescence excitation spectrum of a single, naturally formed gallium arsenide (GaAs) quantum dot have been measured with high spatial and spectral resolution. The energies and linewidths of the homogeneous spectrum provide a new perspective on the dephasing dynamics of the exciton in a quantum-confined, solid-state system. The origins of the linewidths are discussed in terms of the dynamics of the exciton in zero dimensions, in particular, in terms of lifetime broadening through the emission or absorption of phonons and photons.

Journal Article↗
PubMed1996

Videoconferencing in psychiatry: a survey of use in northern Norway.

A survey of the use of videoconferencing in mental health care was carried out in northern Norway. A questionnaire was distributed to all user institutions in northern Norway at the same time that ISDN became available, in mid-1995. The questionnaire completion rate for locations recorded as participants in videoconferencing sessions was 62%. Within six months, a total of 1028 persons had participated in 140 videoconferencing sessions from 35 institutions. The purposes of videoconferencing included meetings (50%), supervision, training and teaching (31%), clinical consultations (14%) and tests or demonstrations (5%). The alternative forms of contact which videoconferencing replaced included travel (59%), no contact (25%), telephone (14%), and mail or fax (2%). No problems were reported in 55% of the sessions; in 19% there were audio problems, in 14% there were picture problems, in 5% attempts to connect failed and in 5% disconnection occurred. The majority of users (87%) reported that they were satisfied or very satisfied with the facility; 8% were uncertain and 5% were less satisfied or totally dissatisfied. Continued surveying will provide longitudinal data on the diffusion of telepsychiatry in northern Norway.

Attitude of Health Personnel↗
PubMed1995

[Psychotherapeutic counselling via telecommunication networks].

The article discusses the effects that video conferencing in psychotherapy (distant therapy) may have upon the interaction between client and therapist. Experiences from distant therapy in North Norway, as well as earlier studies, are discussed in relation to factors such as client power and control, regulation of intimacy, and verbalization. The experiences indicate that physical presence--which is intuitively perceived as the ideal in relation to which the distant therapy settings are assessed--should be treated instead as a variable which can have positive and/or negative effects on a given therapeutic process.

Child↗