PubMed Health⌕ Search

Biomedical subjects

R G Olsen

Publications and source records attributed to R G Olsen.

At least 55 records · Page 3Linked to original sources

Specific absorption rate in models of man and monkey at 225 and 2,000 MHz.

Full-size models of a man and a rhesus monkey were exposed to radiofrequency (RF) radiation at 225 MHz. The model of man was also exposed to 2,000 MHz. Specific absorption rates (SARs) were measured in partial-body sections, such as the arms, legs, etc., using gradient-layer calorimeters. Also, front-surface thermographic images were obtained to qualitatively show the heating patterns. For all of the configurations used, the SAR in the limbs was much higher than in the torso. Agreement (whole-body SARs) with spheroidal models was better for both models at 225 MHz than at 2,000 MHz. These results indicate that in the frequency range two orders of magnitude above whole-body resonance, SAR in the limbs significantly contributes to the whole-body average SAR.

Animals↗

Feline leukemia virus: current status of the feline induced immune depression and immunoprevention.

This is a review of the current knowledge of feline leukemia virus (FeLV) associated with immune depression observed in cats. It will focus on the clinical and experimental observations associated with feline retroviral infection and presence in vivo and in vitro. We will briefly describe retroviral-associated acquired immune deficiency syndrome associated with FeLV infection in the cat and specific cellular pathology associated with FeLV latency. In addition, we will focus on the action of FeLV-p15E in vitro and describe possible mechanisms of the FeLV-associated immunosuppression observed both in vivo and in vitro. Lastly, we will evaluate the current status of immunoprevention of FeLV. We will not attempt an in-depth analysis of the current literature; our focus is to review current findings as they relate to feline AIDS and immunotherapy.

Acquired Immunodeficiency Syndrome↗

Serological and virological evidence of human T-lymphotropic virus in systemic lupus erythematosus.

We present evidence that systemic lupus erythematosus (SLE) patients, but not other mixed connective tissue disease patients, have been exposed to a retrovirus similar or identical to known human T-lymphotropic viruses (HTLV). Serological studies demonstrated a high incidence of seropositivity in SLE patients to HTLV-I antigens by indirect immunofluorescence and Western blot analysis, and to HTLV-III by Western blot analysis. Furthermore, peripheral blood mononuclear cells from four patients with SLE cultivated in vitro expressed HTLV-I antigens after 3 days or more in culture, and reverse transcriptase activity was detected in supernatants from short-term cultures.

Antibodies, Viral↗

Immunosuppression by canine distemper virus: modulation of in vitro immunoglobulin synthesis, interleukin release and prostaglandin E2 production.

In vitro or in vivo infection of canine mononuclear cells by canine distemper virus (CDV) in short-term microcultures resulted in suppression of lectin-induced 3H-thymidine incorporation. This suppressive effect was also evident in pokeweed mitogen-driven in vitro immunoglobulin synthesis and release. Lectin-induced interleukin-2 production by monocyte-depleted lymphocyte cultures was marginally affected by CDV, whereas interleukin-1 production by adherent mononuclear cells was significantly depressed. Monocyte cultures established from viremic dogs released prostaglandin (PG)E2. The results suggest that, in addition to a direct viral effect upon lectin responsive cellular population(s), CDV modulates monocyte functions by inhibition of interleukin-1 production and by enhancing PGE2 release.

Animals↗

Chronic fatal disease in gorillas seropositive for simian T-lymphotropic virus I antibodies.

Sera from 10 gorillas were tested by indirect immunofluorescent antibody assay, Western blotting and ELISA to Human T-lymphotropic viruses for cross-reacting with antibodies to Simian T-lymphotropic virus I (STLV-I). Four were antibody positive. Of the 4 seropositive gorillas, one has remained healthy, while 3 have died with similar disease problems as reconstructed from clinical records. It is not known whether a causal relationship exists between these diseases and STLV-I retrovirus infection.

Animals↗

Suppression of in vitro neutrophil function by feline leukaemia virus (FeLV) and purified FeLV-p15E.

Feline neutrophils (PMN) were isolated and exposed to ultraviolet light-inactivated feline leukaemia virus (UV-FeLV) and purified envelope component p15E (FeLV-p15E). Functional capacity of exposed PMN was measured in vitro utilizing the chemiluminescence (CL) response. PMN exposed to UV-FeLV demonstrated depressed CL responses to Ca2+-ionophore A23187 and latex particles. However, FeLV-p15E produced significant suppression in the CL response to A23187 but failed to produce significant alterations in response to latex particles. The data indicate that FeLV-p15E may, in part, be responsible for increased morbidity and mortality among FeLV-infected cats through suppression of the PMN population.

Animals↗

Saliva as a source of feline leukemia virus antigen for diagnosis of disease.

An enzyme-linked immunosorbent assay (ELISA) for detection of feline leukemia virus (FeLV) p27 in saliva was tested for its accuracy and sensitivity in diagnosing FeLV infections. Saliva and serum samples from 564 clinical cases were tested with a 99.2% specificity. The overall accuracy of the saliva ELISA reactive to the serum ELISA was 97.9%. Experimentally, the ELISA saliva was the least sensitive in diagnosing early FeLV infections. However, the overall accuracy, ease of use, and simplicity of the test support its use as a screening procedure in clinical practice.

Animals↗

Effects of treatment with cobra venom factor on experimentally induced feline leukemia.

Five- to six-month-old specific-pathogen-free cats were exposed to cobra venom factor (CVF) alone (4 cats), Rickard feline leukemia virus (FeLV; 9 cats), or CVF and FeLV (6 cats). Host-virus relationships were evaluated by monitoring the development of viremia, production of antibody against feline oncornavirus-associated cell membrane antigen, and amount of circulating immune complexes (CIC). Exposure to CVF induced complement depletion, which lasted 8 to 15 days. However, complement depletion did not promote the development of persistent viremia nor alter the production of antibody to feline oncornavirus-associated cell membrane antigen or CIC. Results indicated that the complement system did not protect cats during their initial exposure to FeLV and that an intact complement system was not necessary for the development of antibody against feline oncornavirus-associated antigen or for the formation of CIC.

Animals↗

Identification of calmodulin activity in purified retroviruses.

Several viruses have been shown to require calcium for their function, and to bind calcium at specific sites. However, the nature of the calcium binding molecule on viruses has not been established. One possibility is the ubiquitous calcium-binding protein calmodulin. Our studies were designed to determine whether feline leukemia virus contained calmodulin. Accordingly, we tested purified feline leukemia virus for the presence of calmodulin-like activity. The virus, like authentic calmodulin, activated cyclic AMP phosphodiesterase. The ability of the virus to activate the enzyme was blocked in the presence of the known calmodulin inhibitors trifluoperazine and W-7. This indirect evidence for the presence of calmodulin was confirmed by radioimmunoassay. Several other retroviruses were also tested using radioimmunoassay and found to contain calmodulin. Our results indicate that the calcium binding site in retroviruses may be calmodulin.

3',5'-Cyclic-AMP Phosphodiesterases↗

Feline leukemia vaccine: efficacy, contents and probable mechanism.

An effective subunit vaccine against feline leukemia virus infection and related diseases has been developed. The source of the vaccine immunogen is feline retrovirus persistently infected cells that continuously synthesize and shed virus polypeptides. Western blot analysis identifies FeLV-gp70, p27, p15, p12, and p10 in the subunit vaccine preparation. Cats immunized with the vaccine developed antibodies to a 70,000 MW protein of the vaccine that seems to be distinct from, but related to the FeLV-gp70 polypeptide.

Animals↗

Repeated suppression of lymphocyte blastogenesis following vaccinations of CPV-immune dogs with modified-live CPV vaccines.

A commercially available modified-live canine parvovirus (CPV) vaccine was evaluated for its immunosuppressive properties in eight random-bred dogs, all with circulatory antibody to CPV. Three of the eight dogs exhibited a significant decrease in lymphocyte blastogenesis after vaccine administration. In these dogs, this decrease in blastogenesis was of short duration and was consistently observed after repeated administrations of the vaccine. Neither gastroenteritis, fever nor leukopenia, signs indicative of virulent canine parvovirus infection, were detected in these animals. In addition, lymphocytes from these dogs lacked Ia antigen expression. This study demonstrated that the immunomodulating effects of ML-CPV is not observed in all animals yet is consistent in affected individuals.

Animals↗

Oncogenic viruses of domestic animals.

The objective of this article is to review the relevant oncogenic viruses of small animals. Basic scientific principles that have been discovered by research into feline leukemia and other animal cancer viruses have enhanced our understanding of oncogenesis and have led to practical methods of cancer control and prophylaxis.

Animals↗

Polymorphonuclear leukocyte dysfunction associated with feline leukaemia virus infection.

The chemiluminescent characteristics of enriched (greater than 95%) peripheral blood polymorphonuclear leukocyte populations (PMN) from normal and feline leukaemia virus (FeLV)-infected cats were investigated. FeLV-infected cats demonstrated a significantly lower (P less than 0.001) PMN chemiluminescent response when compared to the response of normal age-matched controls. Normal PMN treated with FeLV-infected cat serum exhibited a depressed response in comparison to control cells. A titration of serum from infected cats supplemented with normal serum revealed a titratable suppression of chemiluminescence with increasing concentration of serum from the infected cats. However, PMN from FeLV-infected cats treated with normal serum displayed a slight increase in chemiluminescence over the same cells in autologous serum. The addition of inactivated FeLV to normal PMN caused a titratable decrease in chemiluminescence.

Animals↗

Indirect immunofluorescence of oral lichen planus.

Sections of lesional tissue from 6 patients who exhibited only oral lesions of lichen planus (LP) were incubated with autologous serum and studied immunopathologically for the presence of lichen planus specific antigen (LPSA). None of the specimens was positive for LPSA. Serum from the oral LP patients was subsequently incubated with allogeneic cutaneous LP lesional tissue sections, which resulted in the demonstration of LPSA in 2 of the 4 sera examined. These results suggest an immunologic relationship between cutaneous LP and at least some cases of oral LP.

Adult↗

Demonstration of depressed polymorphonuclear leukocyte function in nonviremic FeLV-infected cats.

Polymorphonuclear leukocytes (PMN) from healthy, normal control cats and FeLV-infected cats were analyzed for differences in phagocytic capabilities. One week after experimental infection, PMNs from FeLV-infected cats exhibited a marked decrease in phagocytic function as determined by the luminol-dependent chemiluminescent response. Depressed PMN function was observed in these cats during the viremic stage of infection and subsequently remained depressed after the cessation of viremia. The data presented here suggest that while nonviremic cats are reported as clinically normal, they may in fact be exhibiting a suppressed PMN function.

Animals↗

Evaluation of terminal deoxynucleotidyl transferase expression in bone marrow of clinically normal and feline leukemia virus-exposed cats.

Bone marrow cells from 8 specific-pathogen-free and 11 feline leukemia virus-exposed cats were examined for the expression of the nuclear antigen terminal deoxynucleotidyl transferase (TdT). Using a standard indirect immunofluorescence technique, feline leukemia-exposed cats had increased expression of TdT in bone marrow aspirates (2.0% to 29.0%) when compared with that in bone marrow cells from specific-pathogen-free cats (2.5% to 6.0%). Seemingly, TdT can be used as an antigenic marker in leukemogenesis of FeLV-infected cats.

Animals↗

Density-gradient sedimentation of feline bone marrow cells with polyvinyl-pyrrolidone-coated silica gel.

Feline bone marrow cells were separated based on their density distribution in a continuous polyvinyl-pyrrolidone-coated silica gel density gradient. Morphologic identification of cytocentrifuged preparations at specific densities revealed a progressive increase in density with maturation of the cells within the granulocytic and erythroid series. Segmented eosinophils peaked at 1.084 g/ml, monocytes at 1.07 g/ml, and lymphocytes spanned the density of 1.068 to 1.084 g/ml. Bone marrow samples from 6 healthy specific-pathogen-free cats were separated by the continuous polyvinyl-pyrrolidone-coated silica gel gradient and were studied for progenitor colony formation in methylcellulose. Erythroid colony formation was greatest at a density of 1.084 g/ml and also appeared in cells from 4 cats at a lighter density of 1.016 to 1.05 g/ml. Colony formation in the granulocytic series revealed progenitors throughout the gradient with enrichment at 1.055 g/ml.

Animals↗

Microwave radiation absorption in the rat: frequency-dependent SAR distribution in body and tail.

Experiments were conducted using twin-well calorimetry to determine the averaged whole-body specific absorption rate (SAR) for rat carcasses exposed to 360, 700, 915, and 2,450 MHz CW radiation in an anechoic chamber. All exposures were done with the long axis of the rat in an E-polarization. Additional experiments were conducted using a fiber optical temperature probe to determine local SAR in the brain, esophagus, colon, rectum, and tail during microwave exposure. The whole-body averaged SAR for the radiation frequencies examined follows a nonmonotonic function with 700 MHz as the resonant frequency. This result agrees with previous analytical estimates. Local SARs within the body and tail are nonuniform with significant frequency-specific hotspots in the colon, rectum, and tail.

Animals↗