PubMed Health⌕ Search

Biomedical subjects

R G Olsen

Publications and source records attributed to R G Olsen.

At least 73 records · Page 4Linked to original sources
PubMed1985

Reversal of feline retroviral suppression by indomethacin.

The immunosuppressive effect of feline leukemia virus (FeLV) and its 15,000 dalton envelope protein (p15E) were studied to determine if the mechanism of action was due to an increase in prostaglandin production. We examined the effects of exogenous PGE1 and PGE2 on the normal Con A response of feline peripheral blood lymphocytes (PBL) and found them to be inhibitory. The addition of the cyclooxygenase inhibitor indomethacin to cells incubated with FeLV or FeLV p15E and Con A completely abrogated the viral suppressive effects. This reversal was titratable and time-dependent. Other non-steroidal anti-inflammatory (NSAI) drugs were found to have similar actions. Indomethacin was also able to increase the suppressed Con A response of PBL from FeLV-infected cats. Upon measurement of PGE2 levels from PBL cultured with FeLV, we found a decrease in PGE2 accumulation associated with FeLV presence during the first 24 h of culture. These findings indicate that FeLV does not cause its immunosuppressive effects by increasing PG production and suggests that indomethacin and the other tested NSAI drugs do not produce their effect by PG inhibition.

Animals↗
PubMed1985

The reversal of feline retroviral-induced suppression of lymphocyte Con A receptor mobility by indomethacin and PGE2.

Ultraviolet light-inactivated feline leukemia virus (FeLV) and its 15,000 dalton envelope protein (p15E) inhibited concanavalin A receptor motility of feline peripheral lymphocytes (PBL). In contrast, the virus had no effect on immunoglobulin capping of feline PBL. The inhibitory action of FeLV and FeLV p15E was reversed by the addition of indomethacin. The indomethacin effect was titratable and gave significant reversal between 1 X 10(-5) and 1 X 10(-10) M. The indomethacin inhibition of the prostaglandin synthesis does not appear to be the mechanism of action in its ability to reverse FeLV suppression of Con A receptor mobility. Since the addition of prostaglandin E2 (PGE2) (1.0 microM) was also able to reverse the FeLV-induced inhibition and neither indomethacin nor PGE2 had an observable effect on Con A receptor mobility of normal PBL without FeLV present. PBL from FeLV-infected cats were sensitive to indomethacin (1.0-10.0 microM) and an indomethacin-related increase in cap formation was observed. Since both indomethacin and PGE2 were able to reverse the FeLV-induced suppression it was concluded that their mechanism of action may be through a common site. In addition, indomethacin may prove useful as an immune response modifier for therapy in FeLV-infected cats.

Animals↗
PubMed1985

Effects of cobra venom factor treatment on latent feline leukemia virus infection.

The role of the complement system in containment of feline leukemia virus infection was studied by cobra venom factor treatment of feline leukemia virus-immune cats. One to three weeks after cobra venom factor treatment, an increase in viral antigen in marrow myelomonocytic cells and circulating immune complexes was noted. Prevention of reactivation of feline leukemia virus infection may in part depend on an intact complement system.

Animals↗
PubMed1985

Retrovirus-mediated immunosuppression. I. FeLV-UV and specific FeLV proteins alter T lymphocyte behavior by inducing hyporesponsiveness to lymphokines.

Murine splenocytes were used to study the in vitro immunosuppressive effects of UV-inactivated feline leukemia virus (FeLV-UV). FeLV-UV blocks both alloantigen (DBA/2)-induced and Con A-induced proliferation of C57BL/6 splenocytes in a dose-dependent manner. Furthermore, C57BL/6 anti-DBA/2 mixed lymphocyte cultures containing FeLV-UV fail to develop detectable DBA/2-specific cytolytic activity, although FeLV-UV has no effect on the cytolytic activity of preformed C57BL/6 anti-DBA/2 cytolytic T cells (CTL). Disruption of lymphocyte proliferation and CTL generation by FeLV-UV could not be overcome by the addition of exogenous lymphokines. These data suggest that FeLV-UV can interfere with the lymphokine reactivity of alloactivated lymphocytes. In fact, FeLV-UV blocks the lymphokine-induced proliferation of the murine IL 2-dependent cell line CTLL-20. The CTLL-20 cells were subsequently used to study the mechanism(s) by which retroviruses alter T lymphocyte function. Normally, CTLL-20 cells undergo significant proliferation when cultured in EL4 SN, an IL 2-containing culture supernatant from PMA-stimulated EL4 cells. This lymphokine-induced CTLL-20 proliferation is abrogated in a dose-dependent manner by UV-inactivated murine leukemia virus (MuLV-UV), FeLV-UV, and a purified 15,000 dalton viral protein, p15, derived from FeLV. Suppression of CTLL-20 proliferation requires only brief contact (6 hr) with FeLV-UV or with p15, but is most efficient after prolonged (24 hr) contact with these agents. Furthermore, suppression of CTLL-20 proliferation by FeLV-UV and p15 is reversible, because CTLL-20 cells which have been pretreated for 24 hr with FeLV-UV or p15 are equally as efficient at responding to EL4 SN as untreated CTLL-20. Additional studies indicate that CTLL-20 cells continue to remove IL 2 activity from EL4 SN in the presence of suppressive concentrations of FeLV-UV, and that suppressive concentrations of FeLV-UV do not remove IL 2 activity from EL4 SN. This suggests that FeLV does not block CTLL-20 proliferation by absorbing or inactivating IL 2, or by occluding IL 2 receptors, and that T lymphocytes develop an insensitivity to lymphokines after contact with FeLV-UV, which may be caused by a metabolic, rather than an immunologic, defect. Because lymphokines are requisite signals for T cell function, considerable immunosuppression would be associated with acquired lymphokine insensitivity.

Animals↗
PubMed1985

Retrovirus-mediated immunosuppression. II. FeLV-UV alters in vitro murine T lymphocyte behavior by reversibly impairing lymphokine secretion.

Murine splenocytes and cloned murine T cells were used to study the in vitro immunosuppressive effects of UV-inactivated feline leukemia virus (FeLV-UV) on lymphokine secretion. FeLV-UV can significantly depress the accumulation of IL 2 in cultures of Con A-stimulated C57BL/6 splenocytes and in cultures containing the alloreactive helper T cell clone B6D/2-2m plus Con A. Inhibition of lymphokine accumulation in these cultures could not be attributed to absorption or inactivation of IL 2 by the FeLV-UV or to the FeLV-UV-induced production of substances which interfere with the IL 2 bioassay. Thus, FeLV-UV appears to block production and/or secretion of IL 2 by a direct inhibitory effect on IL 2-secreting murine T lymphocytes. Additional studies indicate that FeLV-UV impairs IL 2 production only if added very soon after lymphocyte contact with lymphokine-inducing agents and that IL 2 secretion resumes when FeLV-UV is removed from the culture. FeLV-UV also impairs accumulation of MAF (interferon-gamma?) in cultures of Con A-stimulated C57BL/6 splenocytes and in cultures containing the alloreactive cytotoxic T lymphocyte clone B6D/2-7c plus Con A. The latter observation again suggests that FeLV-UV impairs lymphokine secretion by a direct effect on lymphokine-producing T lymphocytes. Furthermore, it suggests that FeLV-UV does not selectively impair production of IL 2 nor does it have selective inhibitory effects on helper T cells. Rather, FeLV-UV appears to have a general inhibitory effect on lymphokine production by T lymphocytes. Finally, concentrations of FeLV-UV which suppress MAF production by the CTL clone have little influence on the cytolysis mediated by the same cloned T cell population. Thus, the immunosuppressive influence of FeLV-UV is selective for phenomena associated with induction of new T lymphocyte functions, such as lymphokine secretion, and spares other immune functions already expressed by the same cells.

Animals↗
PubMed1985

Retroviral-associated eosinophilic leukemia in the cat.

Fourteen specific-pathogen-free cats were inoculated with a putative env gene recombinant feline retrovirus, PR8. An isolate of the Rickard strain of feline leukemia virus (FeLV-R), PR8, has the properties of both an exogenous (FeLV-R) and an endogenous (xenotropic) feline retrovirus (RD-114). Twelve of the PR8-inoculated cats developed viremia; 2 of the 12 cats developed eosinophilia, with 1 being diagnosed with eosinophilic leukemia and the other with extreme eosinophilic hyperplasia. Eosinophilic leukemia is rare in cats and has not previously been associated with retroviral infection. Changes in the viral envelope properties may have altered the pathogenicity of the exogenous virus to cause this rare form of leukemia.

Animals↗
PubMed1984

A circular waveguide irradiation system for nonhuman primates: design and dosimetry.

A 275-MHz exposure system, consisting of a circular waveguide irradiator and a transparent plastic animal cage, has been developed to accommodate rhesus monkeys weighing up to 15 kg. The vertically oriented waveguide is composed primarily of stainless steel and is fitted with an inner cage fabricated from a tubular section of acrylic plastic. Circularly polarized electromagnetic energy at 275 MHz, either pulsed or continuous wave (CW), can be propagated from the removable top section of the waveguide. The cage is designed to function as the monkey's permanent home. It is fitted with a lever-actuated behavioral performance device on which the monkey responds according to a predetermined schedule to obtain a daily food ration. The system can be adapted to provide for the collection of metabolic and physiologic data as well. Dosimetric measurements were conducted with six rhesus monkeys weighing 3.0-7.2 kg and with a 4-kg model. The dosimetric results show that about one-third of the net incident energy is absorbed by a subject in this system at a normalized specific absorption rate (SAR) of 0.33 (W/kg)/(mW/cm2).

Animals↗
PubMed1984

Serum from lichen planus patients reacts with fetal skin tissues.

Lichen planus specific antigen (LPSA) is a lesion-specific marker that differentiates lichen planus from other dermatoses. Serum from lichen planus patients reacted in the indirect immunofluorescent test with fetal epidermis. The reaction was not observed between serum from people with no clinical history of lichen planus and fetal skin tissues. Adsorption of lichen planus serum with a fetal skin extract removed the antibody to LPSA. Adsorption with equivalent amounts of adult normal skin did not remove the serologic activity of LP serum to fetal skin. ELISA test serum from lichen planus patients bound to fetal skin antigen extract to a greater extent than did serum from normal individuals or from patients with non-lichen planus dermatoses, although the quantity of antibody bound in these three groups was not significantly different.

Antibodies↗
PubMed1984

Feline one-way mixed leukocyte reaction.

The feline one-way mixed leukocyte reaction (MLR) was accomplished by a microtechnique assay using gradient purified mononuclear leukocytes from the peripheral blood of specific-pathogen-free (SPF) cats. An eight day assay was required with an appropriate serum supplement of rabbit or cat serum and obtainable cell concentrations of 1 X 10(5) mononuclear cells per well of each responder and stimulator population. This assay was devised as an in vitro correlate of cell-mediated immunity and to demonstrate that feline histocompatibility differences can be detected in culture.

Animals↗
PubMed1984

Detection of circulating immune complexes by a Clq/protein A-ELISA during the preneoplastic stages of feline leukemia virus infection.

A microscale ELISA immune complex assay which utilized a solid phase C1q and a Protein A-peroxidase enzyme conjugate is described. This ELISA was used to detect and quantitate circulating immune complexes (CIC) during the initial feline leukemia virus infection. Significant increases in CIC were seen in the cats which were transiently infected at weeks three through eight after viral exposure. A persistent elevation in CIC was observed in the one cat which developed a persistent viremia. The addition of EDTA to the serum strongly interfered with this assay.

Animals↗
PubMed1984

Use of indirect immunofluorescence in the lupus erythematosus/lichen planus overlap syndrome: an additional diagnostic clue.

The lupus erythematosus (LE)/lichen planus (LP) overlap syndrome comprises a heterogeneous group of patients who demonstrate clinical, histologic, and immunopathologic characteristics of two diseases. We report six patients with the syndrome who were evaluated by a double-layer indirect immunofluorescence (IF) technic using patient serum and autologous lesional skin as substrate followed by conjugate. This test demonstrated intense staining of the stratum granulosum in two patients, a finding previously shown to be consistent with LP. A third patient developed criteria for the diagnosis of systemic LE with corroborating direct IF findings and a negative indirect IF assay. This preliminary study provides evidence for a possible way of distinguishing LE from LP in some patients with the overlap syndrome.

Adult↗
PubMed1984

Indirect immunofluorescence microscopy of lichen planus.

Indirect immunofluorescence microscopy using serum and lesional skin revealed a lichen planus specific antigen (LPSA) in 80% of patients with lichen planus. This antigen is found only in the stratum granulosum and stratum spinosum. It was demonstrated in skin lesions in Caucasians and Negroes in South Africa and the U.S.A. but was not found in the skin of normal people or patients with other dermatoses. Indirect immunofluorescence should prove useful in distinguishing atypical forms of lichen planus from other dermatoses.

Adolescent↗
PubMed1984

Inhibition of erythroid colony-forming cells by a Mr 15,000 protein of feline leukemia virus.

The effects of concentrated ultraviolet-inactivated feline leukemia virus (FeLV), the purified Mr 15,000 envelope protein (p15E) of FeLV, or the purified Mr 27,000 structural protein (p27) of FeLV on feline bone marrow mononuclear cells were studied in vitro in methylcellulose cultures. Whole virus and purified viral proteins were from the Kawakami-Theilen isolate of FeLV, which induces erythroid aplasia in cats. Bone marrow mononuclear cells from FeLV-negative young adult cats were preincubated with a medium control, ultraviolet-inactivated whole virus, or the p15E or p27 of FeLV, incubated in methylcellulose cultures for 2 days, and then observed for the formation of colony-forming units-erythroid (CFU-E) and colony-forming units-granulocyte/macrophage. The ultraviolet-inactivated Kawakami-Theilen isolate of FeLV at concentrations of 10 or 20 micrograms of viral protein/5 X 10(4) cells suppressed CFU-E to 66 to 56% of control values but had no significant effect on proliferation of colony-forming units-granulocyte/macrophage. p15E at concentrations of 0.1 to 0.2 micrograms/5 X 10(4) cells decreased CFU-E numbers to 0 to 1% of control values, whereas the same concentration of p27 did not alter CFU-E growth when compared with controls. Neither p15E nor p27 had a significant effect on growth of colony-forming units-granulocyte/macrophage. The erythrosuppressive effects of whole virus and an envelope-derived protein but not a structural core protein suggest that FeLV envelope proteins are important in the selective inhibition of erythrogenesis observed in vivo in FeLV-infected cats.

Animals↗
PubMed1984

Hypothermia and electromagnetic rewarming in the rhesus monkey.

Five male rhesus monkeys (Macaca mulatta) were subjected, under ketamine anesthesia, to repeated hypothermia treatments that produced an average rectal temperature of 28.3 degrees C. Following hypothermia induction, the subjects were rewarmed using either a ventrally applied surgical heating pad supplied with 35 degrees C water or a radio-frequency (RF) induction coil operating at 13.56 MHz with an average specific absorption rate (SAR) calculated to be approximately 5.5 W X kg-1. A special temperature probe, nonperturbing to RF, was used in the RF rewarming experiments. Control experiments were also conducted in which only ketamine was administered over a 3-h period. RF rewarming to 35 degrees C typically required only 50 min; whereas, an average of 137 min was required for heating-pad rewarming. Analyses of blood serum collected during and up to 48 h after hypothermia treatments showed elevations at 24 h in creatine phosphokinase (CPK), lactic dehydrogenase (LDH), and glutamic oxaloacetic transaminase (GOT), and these elevations were highest for the ketamine controls and lowest for the RF rewarming experiments. The subjects have been periodically examined since these experiments, and all appear to be in good health. It is concluded that the careful application of RF energy to the central core of the body can successfully be used for rewarming purposes, is more effective than externally applied rewarming techniques, and is potentially useful in remote locations.

Animals↗