Bridged peptides: synthesis, spectroscopy, and computer simulations.
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Amino Acid Sequence↗
Biomedical subjects
R Glaser
Publications and source records attributed to R Glaser.
Induction of a deoxyuridine triphosphate nucleotidohydrolase activity in Epstein-Barr virus-infected cells.
Superinfection of Raji cells with Epstein-Barr virus (EBV) or chemical induction of HR-1 cells with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) results in the induction of a deoxyuridine triphosphate nucleotidohydrolase (dUTPase) which is not observed in mock-treated cells or TPA-treated EBV genome-negative BJAB cells. The EBV-induced dUTPase could be distinguished from the host dUTPase based upon differences in their migration in polyacrylamide gels and sensitivity to the 5-mercurithioguanosine derivitive of dUTP. The expression of the EBV-specified dUTPase is prevented by phosphonoacetic acid indicating that its expression is dependent upon EBV-DNA replication.
Antiviral Agents↗
Distress and DNA repair in human lymphocytes.
This research assessed differences in DNA repair in lymphocytes from high- and low-distressed individuals. A median split on Minnesota Multiphasic Personality Inventory (MMPI) Scale 2 divided 28 newly admitted nonpsychotic psychiatric inpatients into high- and low-distress subgroups. The high-distress subgroup had significantly poorer DNA repair in lymphocytes exposed to X-irradiation than low-distress subjects. We also found that lymphocytes obtained from this psychiatric sample had significantly poorer DNA repair than lymphocytes from nonpsychiatric control subjects when compared 5 hr after X-irradiation. A high level of distress therefore appears to be associated with significant dysfunctional differences at the molecular level which may have important implications for health. These data provide evidence for a direct pathway through which distress could influence the incidence of cancer.
Adult↗
Stress, loneliness, and changes in herpesvirus latency.
This study used a prospective design to examine the influence of examination stress and loneliness on herpesvirus latency as measured by changes in antibody levels to three herpesviruses, Epstein-Barr virus (EBV), Herpes simplex type I (HSV-1), and cytomegalovirus (CMV). Three blood samples were obtained from 49 first-year medical students, with the first sample drawn 1 month before final examinations, the second on the first day of final examinations, and the third during the first week after their return from summer vacation. A median split on the UCLA Loneliness Scale divided subjects into high- and low-scoring loneliness groups. There were significant changes in the antibody titers to all three herpesviruses across the sample points, with the lowest levels found in the third (low stress) sample. High-loneliness subjects had significantly higher EBV antibody titers than low-loneliness subjects. These data suggest that stress-related immunosuppression can significantly modulate herpesvirus latency.
Adult↗
Shape transformation of erythrocyte ghosts depends on ion concentrations.
Resealed human erythrocyte ghosts undergo shape transformations similar to those of intact erythrocytes. The results indicate that the shape of these ghosts depends on the inner as well as on the outer NaCl concentration. A correlation between shape and calculated transmembrane potential was established similar to that for intact human erythrocytes.
Cations↗
Influence of the intracellular and extracellular cation concentration on monovalent cation efflux of resealed human erythrocyte ghosts.
Tracer efflux measurements (86Rb+ and 22Na+) were performed on resealed human erythrocyte ghosts at different intra- and extracellular NaCl concentrations. Using a modified Goldman equation the observed alterations of the rate constants could be explained by taking into account the transmembrane and surface potentials, at constant permeability coefficient. These results emphasize the importance of membrane surface potentials in triggering ion transport across biological membranes.
Biological Transport, Active↗
Stress-related impairments in cellular immunity.
The percentages of total T-lymphocytes (OKT-3+), helper T-cells (OKT-4+), and suppressor T-cells (OKT-8+) were significantly lower in blood samples obtained from 40 medical students during examinations, compared to baseline values obtained 6 weeks earlier. In addition, the response of T-lymphocytes to stimulation by phytohemagglutinin and concanavilin A was also significantly lower during examinations, compared to baseline. Self-report data documented significantly greater distress associated with examinations. The data have implications for immunosuppressive disorders and stress-related illnesses.
Adult↗
Psychosocial enhancement of immunocompetence in a geriatric population.
This study assessed the enhancement of immunocompetence by relaxation and social contact in 45 geriatric residents of independent-living facilities. Subjects were randomly assigned to one of three protocols: relaxation training, social contact, or no contact. Subjects in the relaxation and social-contact conditions were seen individually three times a week for a month. Blood samples and self-report data were obtained at baseline, at the end of the intervention, and at a 1-month follow-up. At the end of the intervention, the relaxation group showed a significant increase in natural killer cell activity, and significant decreases in antibody titers to Herpes simplex virus and self-rated distress; the other two groups showed nonsignificant changes. There was a general increase in the T-lymphocyte response to phytohemagglutinin stimulation at the end of the intervention, with greater change at lower mitogen concentrations. These data suggest that cellular immunocompetence may be enhanced by psychosocial interventions.
Aged↗
Effects of stress on methyltransferase synthesis: an important DNA repair enzyme.
The enhancement of tumor development following acute stress has been demonstrated in some animal studies. This study was designed to explore mechanisms that would account in part for the relationship between stress and tumor development at the level of DNA repair, using a rat model. Forty-four rats were given the carcinogen dimethylnitrosamine in their drinking water, and half were randomly assigned to a rotational stress condition. The levels of methyltransferase, a DNA repair enzyme induced in response to carcinogen damage, were significantly lower in spleens from the stressed animals. These data suggest that stress may impair DNA repair.
Animals↗
Respiratory monitoring for children undergoing radiation therapy.
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Anesthesia, General↗
Changes in Epstein-Barr virus antibody titers associated with aging.
Antibody titers to the Epstein-Barr virus (EBV), early antigen (EA) IgG, and virus capsid antigen (VCA) IgG and IgA, were measured in 44 geriatric subjects to determine if the depression in cellular immunity known to be associated with aging affects the expression of latent EBV. Similar assays were performed on plasma obtained from a young adult (medical student) population as a control group. We found that 89% of the geriatric samples were positive for EA IgG, and 83% of the plasma obtained from medical students were positive for EA IgG. One hundred percent of the geriatric subjects were positive for VCA IgG, and 87% of the medical students were positive for VCA IgG. Seven percent of the medical student blood samples were positive for VCA IgA; in contrast, 36% of the blood samples obtained from the geriatrics subjects were positive. Significant differences were also found in the geometric mean titers (GMT) of antibodies to EBV antigens; the GMT to EBV EA and VCA were significantly higher in the geriatric group. The data suggest that there may be some loss of control over latent EBV by the cellular immune response in geriatric individuals.
Adolescent↗
Sudden hearing loss following infectious mononucleosis: possible effect of altered immunoregulation.
Sudden, permanent hearing loss developed in three young patients. In an attempt to determine a viral etiology, their humoral and cell-mediated responses to a panel of seven viruses linked to deafness and altered immunity were measured. Although a specific viral cause was not determined, a mild Epstein-Barr virus infection was documented for each patient. It had preceded their hearing loss onset by 1 to 4 months. Evidence of altered cell-mediated responses to Epstein-Barr virus antigens was found in each patient. It is proposed that, in certain susceptible individuals, a temporary cellular immunosuppression, which accompanies normal recovery from Epstein-Barr virus infection, may provide an opportunity for a viral invasion of, or a latent viral reactivation in, the inner ear. This invasion or reactivation leads to deafness.
Adolescent↗
[Isolation of a new strain of EB virus with lytic and transforming properties].
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Antigens, Viral↗
Stress and the transformation of lymphocytes by Epstein-Barr virus.
Although various stressors appear to influence herpesvirus infections, the underlying mechanisms have not been studied. A prospective design was used to examine the effects of examination stress and loneliness on the transformation of B lymphocytes in mixed cultures of T and B lymphocytes by Epstein-Barr virus (EBV). Three blood samples were drawn from 42 EBV-seropositive medical students, with the baseline sample taken 1 month before their final examinations, the stress sample drawn on the first day of final examinations, and the third sample taken the first week after their return from summer vacation. A median split on the UCLA Loneliness Scale divided the subjects into high- and low-scoring loneliness groups. There were significant effects for change over trials, with the lowest transformation levels (i.e., more virus required to transform cells) found in the stress sample. There was also a significant main effect for loneliness, in which high loneliness was associated with lower transformation levels. Possible immunological pathways for the observed changes are discussed.
Antibody Formation↗
Influence of surface charge and transmembrane potential on rubidium-86 efflux of human red blood cells.
The dependence of the rate constant of Rb+ efflux on extracellular cation concentration was measured. At low ionic strengths Rb+ efflux increased strongly. Permeability coefficients were calculated from the rate constants measured, using the Goldman flux equation, with and without making allowance for surface potentials. Only when allowance was made for surface potentials and the associated differences between ion concentrations in the bulk solutions and at the membrane surface, the permeability coefficient remained constant. Best agreement between experimental data and theoretically calculated values was obtained when an interior surface potential of -110 mV was assumed. When the surface charge of erythrocytes is reduced by neuraminidase, the rate constants for Rb+ efflux decreased, indicating a significant influence of surface potential.
Chlorides↗
Hematologic and immunologic responses in common marmosets (Callithrix jacchus) infected with Plasmodium knowlesi and Epstein-Barr virus.
The hematologic and immunologic responses to infection with either the Epstein-Barr virus alone or infection with Epstein-Barr virus and Plasmodium knowlesi were studied using common marmosets (Callithrix jacchus). The assays performed included complete blood cell counts, determinations of natural killer cell activity, and determinations of antibody titers to Epstein-Barr virus early antigen, virus capsid antigen and the nuclear antigen. While no animal showed signs of lymphoproliferative disease, it was found that animals infected with Epstein-Barr virus became positive for early antigen, virus capsid antigen and nuclear antigen at low levels. No difference in antibody titers between Epstein-Barr virus infected animals and co-infected animals was observed. An increase also was found in the number of leukocytes in all groups, and an increase in natural killer cells following infection with Epstein-Barr virus. Some depression in natural killer cells was observed in the co-infected animals when compared to Epstein-Barr virus infected animals.
Animals↗
The kinetics of the Cl-pH equilibration in human red blood cells.
If erythrocytes were transferred into solutions of different ionic composition, they changed the inner pH and chloride concentration until reaching a new quasi-equilibrium state (C-State). Electrochemical measurements were performed to follow the kinetics of this adaption and to answer the question whether the time constant of unidirectional chloride flux or time constant of chloride net flux is responsible for this process. It was found that the kinetics depend strongly on the kind and the concentration of the buffer system used. In unbuffered solutions, a new Cl-pH-equilibrium is reached very fast and proceeds by the Cl-/HCO-3-exchange. If Tris or phosphate buffer were used, this process had a time constant of about 10(-3) S-1 and was mainly realised by a Cl-/OH-exchange or Cl-H+-cotransport. If the suspension contained phosphate, an overshoot of pH took place. The reason for this behavior is the additional exchange of Cl- for HPO2-(4) + H+.
Biological Transport, Active↗
Functional mapping of the Epstein-Barr virus genome: identification of sites coding for the restricted early antigen, the diffuse early antigen, and the nuclear antigen.
Attempts were made to functionally map antigenic expression of the Epstein-Barr virus (EBV) to specific regions on the EBV genome, using the B95-8 strain. Experiments were performed to map the expression of early antigen (EA), both restricted and diffuse (R and D, respectively), and the EBV nuclear antigen (EBNA), using intact B95-8 DNA, cloned BamHI fragments or Charon 4A fragments. DNA preparations were microinjected into two EBV genome-negative epithelial tumor cell lines. Expression of EBV antigens was monitored using precharacterized human sera, as well as monoclonal antibodies to EA-R and EA-D. The data suggest that EA-R maps to the BamHI H fragment, and EA-D maps to the Charon 4A fragment 7. A previous report that BamHI K is associated with the expression of a nuclear neoantigen tentatively identified as EBNA (W.P. Summers, E.A. Grogan, D. Shedd, M. Robert, C.R. Liu, and G. Miller, Proc. Nat. Acad. Sci. USA 79, 5688-5692, 1982) was also confirmed.
Antibodies, Monoclonal↗