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Biomedical subjects

D S Gregerson

Publications and source records attributed to D S Gregerson.

67 records · Page 4Linked to original sources
PubMed1983

Immunologic and biochemical properties of several retinal proteins bound by antibodies in sera from animals with experimental autoimmune uveitis and uveitis patients.

Sera from guinea pigs and rabbits with and without experimental autoimmune uveitis (EAU) induced by immunization with retina, choroid, optic nerve, retinal rod outer segments (ROS) and purified bovine S-antigen were tested for the ability to immunoprecipitate 125I-labeled, detergent-solubilized bovine retinal proteins. The results demonstrate that three major protein antigens with m.w. of 50,000 (p50), 35,000 (p35) and 27,000 (p27) and several minor activities between 30,000 and 60,000 m.w. are recognized by antibodies from these animals. The p50 component was immunoprecipitated by sera from animals immunized with whole retina homogenate, the high speed supernatant of whole retina homogenate, ROS, and S-antigen, and has been identified as S-antigen in competition experiments. The p35 band appeared when sera were used that were raised against antigen preparations containing membrane-bound retinal protein, i.e., whole retina homogenate, ROS, and washed ROS, and thus appears to be an ROS membrane protein. The p27 band was found when sera raised against ROS, washed ROS, optic nerve and whole retina homogenate were used, suggesting it is a membrane-bound antigen common to ROS and optic nerve. Serum from animals immunized with homologous choroid did not immunoprecipitate a detectable product. S-antigen and p35 were also precipitated by some uveitis patient sera. Because S-antigen is also an ROS protein as is rhodopsin, a putative uveitogenic retinal antigen, ROS appear to be an unusually rich source of autoantigenic proteins. S-antigen was also shown to be synthesized in the retina, and the primary translation product was indistinguishable from purified S-antigen by SDS-PAGE, thus eliminating the possibility that it is derived from or is cross-reactive with the 67,000 m.w. rhodopsin kinase.

Animals↗
PubMed1982

Longitudinal study of serum antibody responses to retinal antigens in acute ocular toxoplasmosis.

We conducted a longitudinal study of five patients with anterior and posterior acute toxoplasmic uveitis to determine the relationships, if any, between the level of toxoplasmic activity, therapy, and serum antibody titers to retinal proteins. All patients showed increased serum antibody responses to S-, P-, or p59ag-antigen isolated from bovine retina. The titers to S-antigen tended to decrease with clinical improvement and stabilized at titers somewhat higher than normal; the anti-p59ag titers decreased in those patients treated with clindamycin and sulfadiazine and remained increased throughout the acute attack and remained increased even after the attack ended.

Adult↗
PubMed1982

Serum antibody responses to bovine retinal S-antigen and rod outer segments in proliferative diabetic retinopathy before and after argon laser photocoagulation.

Using the enzyme-linked immunosorbent assay, the serum antibody titers to bovine retinal S-antigen and rod outer segments in pre- and post-argon laser treated diabetic retinopathy patients were compared to each other and to the titers of age- and sex-matched normal controls. The increase in anti-S titer following the initial laser treatment gave a P less than 0.01 using the two-tailed paired Student's t-analysis as compared to the prelaser anti-S titer. Both pre- and post-laser anti-S titers were elevated over normal controls with P values of less than 0.02 and less than 0.001, respectively. Eight weeks after the initial laser treatment, anti-S titers began to decline approaching control levels 12 weeks later. No significant change was found between pre- and post-laser titers when rod outer segments were used as antigen although the pre- and post-laser titers were increased over normal controls with P values of less than 0.05 and less than 0.001, respectively. The release and possible alteration of retinal components following photocoagulation may account for the rise in anti-S titers, while the prephotocoagulation titers may be due to retinopathy-related photoreceptor cell alteration.

Adult↗
PubMed1982

Mycoplasma arthritidis-induced ocular inflammatory disease.

Mycoplasma arthritidis was demonstrated to incite experimental conjunctivitis and uveitis in Swiss Webster mice which have a known susceptibility to the arthritis customarily associated with infection by this mycoplasma. The initial symptom of ocular involvement was conjunctivitis, which appeared as early as 1 day after intravenous injection with viable culture concentrates of M. arthritidis. By day 2, histological analysis showed intraocular localized inflammatory reactions that were confined primarily to the anterior portion of the uvea and produced results which were compatible with those seen in iridocyclitis. Serological assays of the titer and the class of antibodies involved in the early humoral immune response to infection confirmed the predominance of immunoglobulin G (IgG) concentrations over IgM concentrations that was described by others (Cole et al., Infect. Immun. 4:431-440, 1971) and revealed significant titers of the IgG2a and IgG2b subclasses of complement-fixing antibodies. The rapid onset of acute conjunctivitis, together with the early appearance of immunoglobulins of the IgG class, suggests that the M. arthritidis-infected Swiss Webster mice may have experienced an anamnestic response to the mycoplasma antigens. These observations introduce a new animal model for the study of mycoplasma-induced experimental uveitis and conjunctivitis, which are demonstrated here to accompany a disseminated systemic disease process.

Animals↗
PubMed1981

Serum antibody levels of uveitis patients to bovine retinal antigens.

Serum samples from 91 uveitis patients and controls were tested by the enzyme-linked immunosorbent assay technique to determine their relative antibody titers to bovine retinal S antigen and to a detergent extract of saline-washed bovine retina, or P antigen. Only those patients whose uveitis fell into the categories of toxoplasmosis, iritis, herpes keratouveitis, pars planitis, sarcoidosis. Behçet's syndrome, and Vogt-Koyamagi-Harada syndrome are presented in this study. Significantly elevated titers (P less than 0.05) of antibody to S antigen were found in the diagnostic categories of iritis, toxoplasmosis, sarcoidosis, and Behçet's. Elevated titers to the detergent extract were found in iritis (granulomatous and hypopyon subcategories only), toxoplasmosis, sarcoidosis, and Vogt-Koyanagi-Harada syndrome. The anti-S titers of patients treated with systemic steroids were depressed below normal levels. A separate control group of patients with nonuveal ocular inflammations (conjunctivitis, episcleritis, etc.) had titers very similar to normal controls. The posttreatment titers to S antigen of patients receiving laser photocoagulation for diabetic retinopathy were significantly elevated over normal controls.

Antibodies↗
PubMed1980

Processive nature of reverse transcription by avian myeloblastosis virus deoxyribonucleic acid polymerase.

The ribonucleic acid dependent deoxyribonucleic acid polymerase from avian myeloblastosis virus was shown to synthesize poly(dT) transcripts by a processive mechanism using poly(rA)1100.oligo(dT)12-18 as template and primer. Template challenge experiments demonstrate that at low temperature and ionic strength, the polymerase remains bound to the completed template-daughter strand complex after completion of daughter strand elongation. Higher temperatures and ionic strength increase the dissociation of the enzyme from the complex, thus reducing transcript length. Analysis of product size and quantity indicates that the degree of processivity is also influenced by the types and concentrations of metal ions present and indicates that the metal ions affect the activity of the poly(rA) as a template more than they affect processivity or enzyme activity. The results also lead to the conclusion that initiation is the rate-limiting step under all of our experimental conditions. The arguments for a processive as opposed to distributive mechanism are based on an analysis of enzyme-template interactions, product size, and amount of product made under specific reaction conditions.

Avian Leukosis Virus↗
PubMed1979

Characteristics of a retrovirus associated with a hamster melanoma.

The continuous culture of a hamster melanoma cell line has led to the spontaneous appearance of a retrovirus (HaRV) with typical type-C characteristics. The virus differs from all other known hamster viruses in its ability to transform murine as well as rat and hamster cells with apparent one-hit kinetics. Guinea pig, human and feline cells were not transformed although reverse transcriptase activity was detected in the supernatant from infected human cells. HaRV-transformed hamster embryo cells produced solid tumours (all non-pigmented) in 4 out of 35 animals when injected into hamsters while HaRV-transformed murine cells produced no tumours in mice. Injection of HaRV alone in hamsters, mice and rabbits did not induce tumours. HaRV possesses a 70S RNA which dissociates to 35S in DMSO and has a reverse transcriptase which utilizes the 70S virus RNA as a template. The size, morphology and density (1.15 g/ml) are similar to other known type-C viruses. Polyacrylamide gel electrophoresis indicates the presence of polypeptides analogous to those found in other type-C viruses.

Animals↗
PubMed1979

Biochemical and immunological properties of the reverse transcriptase associated with a hamster retrovirus.

Several properties of an RNA-directed DNA polymerase associated with a hamster retrovirus (HaRV) were examined and found to be similar to other polymerases from mammalian type-C viruses in that the enzyme (i) is more active with Mn2+ than Mg2+, (ii) uses the reverse transcriptase-specific poly(rCm).oligo(dG) template, (iii) possesses substantial endogenous polymerase activity and (iv) is strongly inhibited by homologous antisera and moderately inhibited by antisera directed against other type-C viruses. In contrast to previous reports of polymerases from other hamster viruses, HaRV polymerase is active in endogenous assays and the activity is associated with a 70,000 mol. wt. polypeptide in highly purified virions and with 70,000 and 85,000 mol. wt. polypeptides in fresh, unpurified virus. Only one major peak of polymerase activity eluted from DEAE-cellulose while subsequent elution of this peak from phosphocellulose produced two major peaks of polymerase activity. The mol. wt. of these two peaks were 70,000 and 85,000 by glycerol density-gradient sedimentation. The HaRV reverse transcriptase and p30 were found to be most closely related antigenically to other rodent retrovirus proteins.

Animals↗
PubMed1976

The immune response to oxidized ferredoxin. II. Cross reactivity of cells and antisera to modified ferredoxins and the nature of the cells responding in vitro.

The cross reactivity of sera from rabbits sensitized to performic acid oxidized ferredoxin (O-Fd) and of spleen cells from mice sensitized to O-Fd was analysed using several chemically modified forms of ferredoxin in the complement fixation test and the in vitro lymphocyte stimulation assay. Only O-Fd and native ferredoxin (native-Fd) gave positive responses in both assays. Dinitrophenylated-O-Fd (DNP-O-Fd) and acid precipitated ferredoxin (TCA-Fd) were able to fix complement (C') but did not simulate DNA synthesis in vitro. Ferredoxin alkylated with N-ethylmaleimioxin (CM-Fd) was unable to stimulate DNA synthesis and was marginally able to fix C'. Methylated-O-Fd (meth-O-Fd) was not recognized in either assay. The various ferredoxin preparations were tested for their ability to sensitize mice for use in the in vitro lymphocyte stimulation assay. Only O-Fd, NEM-Fd and native-Fd were capable of sensitizing lymphocytes for a proliferative response in vitro to the test antigens. This correlates with the observation that only these antigens were able to induce DNA synthesis in O-Fd-sensitized lymphocytes. The nature of the cells responding in vitro was examined by treating the cells with rabbit anti-mouse immunoglobulin and C' or rabbit anti-mouse brain associated theta and C'. The 24-hr response was found to be sensitive to both sera while the 120-hr response was sensitive only to the anti-theta sera.

Alkylation↗
PubMed1976

The immune response to oxidized ferredoxin. I. Specificity of the response to the amino terminal determinant.

Several synthetic peptide analogues of the amino terminal antigenic determinant (ala-tyr-lysile-ala-asp-ser) of oxidized ferredoxin (O-Fd) were tested for their ability to inhibit the complement fixation reaction between O-Fd and homologous rabbit antiserum, and to inhibit the migration of spleen cells from guinea-pigs immunized to O-Fd or to a conjugate of the amino terminal heptapeptide (N7) and bovine serum albumin (N7-BSA). The results of the migration inhibition assay suggest that the tetrapeptide and longer peptides of the native sequence were all recognized and stimulated the production of migration inhibition factor. Peptides modified at the aspartic residue were partially active while the serine modified peptide was not. Modification at the amino end of the heptapeptide had no effect on migration inhibition. As specificity controls, it was shown that the N7-BSA conjugate inhibited migration in O-Fd immunized animals, while O-Fd inhibited migration in N7-BSA immunized animals. The hexa-, hepta-, aspartic-deleted and serine-modified peptides were able to inhibit the complement fixation reaction with O-Fd and specific rabbit antiserum. Inhibition found with the serine-modified peptide and the lack of inhibition with the amino-modified peptide or the di-, tri-, tetra- and pentapeptides indicates the determinant recognized by the rabbit antibodies is either larger or is located nearer the middle of the heptapeptide than the determinant which induced the production of MIF.

Amino Acid Sequence↗
PubMed1975

Responses of guinea-pig lymphocytes to mitogens, an antigen, and mixed leucocyte culture in media with and without mercaptoethanol and foetal calf serum.

The ability of guinea-pig spleen and lymph node cells to undergo a proliferative response in vitro in the presence of mitogens (concanavalin A and lipopolysaccharide), a specific antigen (oxidized ferredoxin), and allogeneic cells was assessed under a variety of conditions. Time and dose dependency of the responses was measured in RPMI 1640, RPMI 1640 plus mercaptoethanol (ME), RPMI 1640 plus foetal calf serum (FCS), and RPMI 1640 with ME and FCS. Mitogen responses were also measured after treatment of the cells with sheep antiguinea pig immunoglobulin (SaGPIg) and complement (C') or after passage through nylon wool columns. Lipopolysaccharide (LPS) stimulated the cells under all media conditions over a wide range of concentrations but over a narrow time period. Nylon wool treatment of the cells eliminated the LPS response while SaGPIg and C' reduced it. Concanavalin A (con A) stimulated the cells under all test conditions and demonstrated a dose-time interrelationship in terms of maximum response. Pre-treatment of cells with SaGPIg and C' enhanced the response to con A while nylon wool fractionation diminished it somewhat. Only lymph node cells responded in vitro to oxidized ferredoxin (OFd). In serum-free media the OFd responses were maximal at 48 hours whereas in media containing FCS proliferative responses were supported for a prolonged period and appeared to be bimodal. Except for an early response with RPMI 1640 and ME, only media containing FCS supported stimulation in the mixed leucocyte culture.

Animals↗