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Biomedical subjects

L Rasmussen

Publications and source records attributed to L Rasmussen.

At least 145 records · Page 8Linked to original sources
PubMed1984

Large-scale serological screening for cytomegalovirus antibodies in homosexual males by enzyme-linked immunosorbent assay.

We compared an enzyme-linked immunosorbent assay (ELISA) with complement fixation and radioimmunoassay in determining the presence of immunoglobulin antibodies to cytomegalovirus. Of an initial 93 serum samples tested, the correlation between ELISA and radioimmunoassay was 98.9% and that between ELISA and complement fixation was 96.1%. ELISA was used to screen 1,123 homosexual men in San Francisco. Of 479 men attending a homosexual health fair, 35 (7%) lacked cytomegalovirus antibodies by ELISA. Only 15 (2%) of 644 homosexual men attending a municipal sexually transmitted disease clinic were found to be seronegative. All but one of the seronegatives detected by ELISA were also seronegative by radioimmunoassay and complement fixation. We conclude that ELISA can be used to reliably perform large-scale screening for the presence of immunoglobulin G antibodies to cytomegalovirus.

Antibodies, Viral↗
PubMed1982

Virus-specific IgG and IgM antibodies in normal and immunocompromised subjects infected with cytomegalovirus.

Levels of IgG and IgM antibodies t human cytomegalovirus (CMV) were measured using a solid-phase radioimmunoassay. Individuals positive by complement-fixation test consistently had detectable IgG titers by radioimmunoassay, but no quantitative relationship was apparent. An elevated IgM titer was considered specific for CMV infection because sera from individuals with other herpesvirus infections did not cross-react. In patients with mononucleosis, elevated titers of IgM antibody to CMV correlated (P less than 0.001) with active infection and were highest during viremia. Titers of IgG antibody to CMV during and after symptomatic infection were similar to those of asymptomatic positive individuals. Increases in CMV-specific IGM were observed in both primary and reactivated infections in cardiac transplant recipients. In a small group of cardiac transplant recipients with recurrent symptomatic disease, IgM titers were low at the time of viruria and did not increase with CMV tissue involvement, a result which suggests that quantitative deficiencies in IgM may be related to the severity of CMV infections.

Antibodies, Viral↗
PubMed1982

Chemotherapy-induced immunosuppression.

Chemotherapeutic agents are used widely in clinical medicine for the treatment of conditions where diminution of the host immune response is a goal. The clinical use of immunosuppression is indicated for immunologically mediated disease, lymphoproliferative diseases, and prevention of graft rejection. Five categories of agents are useful for these purposes; they are ionizing irradiation, corticosteroids, biological alkylating agents, antilymphocyte sera and antimetabolites. While the specific molecular action of many of these drugs is known, how they affect cellular events in immune responses is less clear. One of the unfortunate sequelae of chemotherapy induced immunosuppression is an increased susceptibility of the host to opportunistic pathogens or malignancies. Specific methods are described for monitoring the various parameters of both humoral and cellular immunity. Studies of immunologic function in lymphoma patients and cardiac transplant patients treated with immunosuppressive drugs have shown specific defects in cell mediated immunity to herpes viruses which may relate to their increased susceptibility to infection by these agents.

Antigens, Viral↗
PubMed1981

Cardiac functioning and blood pressure of 47,XYY and 47,XXY men in a double-blind, double-matched population survey.

This paper reports the electrocardiogram measures and blood pressure of 12 men with 47,XYY, 14 men with 47,XXY, and 52 matched controls with 46,XY. The abnormal karyotypes were identified in a systematic population search for XYY and XXY men. The subjects and their matched controls were examined in a double-blind fashion. Electrocardiogram measures of 47,XYY and 47,XXY men were found to differ from those of 46,XY controls. The XYYs had longer P-R intervals, shorter QRS complexes, and nonsignificantly longer R-R intervals than their matched controls. The XXYs showed longer R-R intervals and trends for for prolonged P-R intervals and shorter QRS complexes when compared with their controls. Trends toward increased within-group variability in the XYY and XXY groups were observed in five of six variance tests, suggesting that the sex chromosome aneuploids have a cardiac condition anomaly. Blood pressure measures of 47,XYY and 47,XXY men were found not to differ from those of 46,XY men. None of the measures revealed a significant difference between the XYYs and the XXYs.

Blood Pressure↗
PubMed1980

Evidence for di-peptide uptake in Tetrahymena.

We have established growth conditions in a synthetic nutrient medium in such a way that utilization of free phenylalanine, but not of phenylalanine-containing di-peptides, limits cell multiplication in species of the genus Tetrahymena (Ciliata). These results suggest that these cells take up intact di-peptides.

Animals↗
PubMed1980

Effect of interferon therapy on circulating lymphocytes in humans.

The effect of interferon treatment on both lymphocyte subpopulation numbers and function was studied in two groups of patients who were being treated systemically with 0.5 to 1.0 x 10(7) units of human leukocyte-derived interferon (HulFN-alpha) daily. Patients with nodular lymphocytic, poorly differentiated non-Hodgkin's lymphoma (NLPD) were given interferon for 30 days and those with chronic hepatitis B infection were treated in cycles for 4 to 7 days. In both patient groups, B lymphocytes numbers were reduced during treatment, but T lymphocyte numbers were unaffected. T lymphocyte responses, measured by blast transformation to herpesvirus antigens were generally low before treatment in NLPD patients. The responses were restored after termination of therapy. In two NLPD patients given two courses of treatment separated by a 3 month interval, the restored T lymphocyte responses were inhibited during the second course of treatment. In patients with chronic hepatitis B virus infection, lymphocyte blast transformation to the viral antigens were also depressed during treatment compared to pretreatment responses. Changes in lymphocyte responses to phytohemagglutinin and pokeweed mitogen were not observed in either patient group.

Antigens, Viral↗
PubMed1979

Peptidase activity in Tetrahymena.

This report strongly suggests that two compartments in Tetrahymena thermophila contain peptidase activity: the cytoplasm and the outer cell surface. Determinations of amino acid concentrations in the extracellular medium upon incubation of cells with peptides suggest that the surface-bound peptidase activity hydrolyses di- and tri-phenylalanine equally fast on a molar basis. Growth experiments designed to characterize the in vivo peptidase specificities showed that both T. thermophila and T. pyriformis can use L-leucyl-L-leucine, but not L-leucyl-D-leucine as a leucine donor. These results are independent of whether the cells form food vacuoles or not.

Animals↗
PubMed1979

Synergistic effects of p-fluorophenylalanine and supra-optimal temperatures on cell division in Tetrahymena pyriformis.

The combined effects of sub-optimal (20 degrees) or supra-optimal (31 degrees C and 34 degrees C) temperatures and the amino acid analogue p-fluorophenylalanine on preparations for cell division in Tetrahymena pyriformis were analysed. A supra-optimal temperature of 31 degrees produced a marked exaggeration of the division-delaying capacity of the analogue. The analogue also sensitises cells when combined with the normal heat shock temperature of 34 degrees, which indicates that division proteins continue to be synthesized at this temperature but cannot be effectively utilized by the cell. These results support the model that preparations involve interactions between and formation of assemblies of proteins on a strict time schedule shortly before division.

Animals↗
PubMed1979

EEG response to sine wave modulated light in XYY, XXY, and XY men.

Ten XYY, 14 XXY, and 47 control XY men were located in a birth cohort of non-institutionalized, tall men. Their EEGs were recorded during stimulation with sine were modulated light; 2.5, 5, 10 and 20 Hz were the modulation frequencies. EEGs with and without stimulation were subjected to power spectral analysis. The frequency-specific EEG change due to visual stimulation (i.e. photic driving) was studied. The XYY subjects showed generally lower levels of driving than their XY controls. At stimulation frequencies of 10 and 20 Hz, the EEG driving in the XYY subjects were significantly smaller when measured in the same frequency bands (i.e. 10 and 20 Hz). In addition, stimulation at 10 Hz elicited a significantly smaller response at the third harmonic frequency (i.e. 30 Hz) in the XYY subjects. No consistent differences in EEG driving were detected between the XXY subjects and their XY controls, or between XXY and XYY subjects.

Adult↗
PubMed1979

Dual capacity for nutrient uptake in Tetrahymena. V. Utilization of amino acids and proteins.

We investigated the relative contributions of phagocytosis and plasma membrane transport to the uptake of amino acids and a protein (egg albumin) in amounts which allow Tetrahymena thermophila to grow and multiply. We used a mutant capable of indefinite growth without food vacuole formation (phagocytosis) and its wild type (phagocytosis-competent) isogenic parental strain. Our results suggest that phagocytosis is not required for free amino acid uptake, most or all of which can be attributed to carrier-mediated transport systems, apparently located on the plasma membrane. In contrast, phagocytosis is required for utilization of the protein. Proteins can supply required amino acids in amounts sufficient for growth only when food vacuoles are formed. We conclude that Tetrahymena thermophila either possesses no endocytic mechanisms at the cell surface other than food vacuole formation or, if it does, these putative mechanisms are not capable of nutritionally meaningful rates of protein uptake.

Amino Acids↗
PubMed1979

Analysis of the time of utilization of proteins for the initiation and completion of division in synchronized Tetrahymena pyriformis.

We exposed division-synchronized Tetrahymena pyriformis to pulse treatments with the structural amino acid analogue p-fluorophenylalanine. We related the timing of the treatments to the delays in onset or completion of division, or both. The results enable us to distinguish between early and late phases in cell division in which the cells bring into action proteins which contribute to initiate and complete division, respectively. Normally, these events are separated by 25-30 min.

Animals↗
PubMed1978

Role of T lymphocytes in cellular immune responses during herpes simplex virus infection in humans.

Lymphocyte blast transformation and interferon production in mononuclear cell culture prepared on Ficoll-Hypaque gradients from individuals with herpes simplex virus-I infection were enhanced by a disease recurrence. Responses to both herpes simplex virus-2 and phytohemagglutinin were unaltered. Transformation to herpes simplex virus-I antigen was adversely affected by depleting either thymus-derived (T) lymphocytes or bone marrow-derived (B) lymphocytes together with monocytes from cultures. The transformation response was reconstructed when the selectively depleted lymphocyte populations were recombined. X-irradiation of either T or B lymphocytes and monocytes showed that T lymphocytes incorporated [3H]thymidine with the aid of a radioresistant non-rosetting cell, probably a monocyte. Depletion of B lymphocytes and monocytes, but not of T lymphocytes, resulted in reduction in interferon production. Irradiated B lymphocytes and monocytes failed to produce significant quantities of interferon, suggesting that a radiosensitive B cell was a major interferon source.

Antigens, Viral↗