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Biomedical subjects

G R Pearson

Publications and source records attributed to G R Pearson.

At least 127 records · Page 7Linked to original sources
PubMed1982

Sera from patients with undifferentiated nasopharyngeal carcinoma contain a factor which abrogates specific Epstein-Barr virus antigen-induced lymphocyte response.

A unique association of Epstein-Barr virus (EBV) with the undifferentiated nasopharyngeal carcinoma (NPC) is a well acknowledged phenomenon. We report here the detection of a factor present in the sera of NPC patients which inhibits the blastogenic response of lymphocytes from EBV seropositive individuals to EB virions or soluble antigens. This lymphocyte-stimulation inhibitor (LSI) was found to be associated with the IgA fraction of the serum immunoglobulins. No inhibitory activity was detected in the sera and their immunoglobulin fractions from healthy (both EBV-seropositive and seronegative) individuals and patients with other carcinomas of the head and neck region. Interestingly, the IgA-LSI was absent in the sera of NPC patients who were successfully treated and remained in remission, while it was readily detectable in the sera of NPC patients in relapse, LSI-positive IgA fractions did not inhibit mitogenic response of lymphocytes to phytohemagglutinin. Taken together, the data presented suggest that LSI is a specific inhibitor of the response of sensitized lymphocytes to EBV antigens and that it may indeed represent a marker of great clinical significance regarding undifferentiated nasopharyngeal carcinoma, particularly for its prognosis.

Antigens, Viral↗
PubMed1982

Uncinariasis in kennelled foxhounds.

Uncinariasis was diagnosed as the cause of unthriftiness in kennelled foxhound pups. Post mortem examination of two pups revealed large numbers of Uncinaria stenocephala embedded in the mucosa of the distal small intestine. The worms were associated with blunting and thickening of villi in this region. The stereoscopic appearance of U stenocephala as seen by scanning electron microscopy is described.

Ancylostomatoidea↗
PubMed1982

Identification of Epstein-Barr virus strain differences with monoclonal antibody to a membrane glycoprotein.

Two monoclonal antibodies directed against Epstein--Barr virus (EBV)-induced membrane antigens (MA) were isolated in this study. On of the monoclonal antibodies, designated 2F5.6, was an IgG2 which, as detected by membrane and fixed cell immunofluorescence, reacted with MA-positive lymphoblastoid cell lines that produced transforming EBV but not with the MA-positive P3HR-1 cell line that produced the lytic, nontransforming strain of this virus. This antibody precipitated the Mr 320,000/350,000 glycoprotein from B-95 virus infected cultures and the Mr 300,000 and 220,000/250,000 glycoproteins from Raji cells superinfected with P3HR-1 virus but did not precipitate any of these EBV-specific glycoproteins from the P3HR-1 cell line. In contrast, the second monoclonal antibody, IgM designated B10.3, reacted with all virus-producing cell lines including the P3HR-1 cell line. The identity of the glycoprotein that serves as the target for this antibody is still unknown. Neither antibody had neutralizing activity against the B-95 or P3HR-1 strain of EBV. These results indicated that the 2F5.6 monoclonal antibody was directed against an antigenic determinant on the major membrane glycoprotein which is common to transforming strains of EBV but absent from the lytic P3HR-1 stain whereas the B10.3 monoclonal antibody was directed against a group-specific EBV-induced membrane determinant.

Antibodies, Monoclonal↗
PubMed1982

Evidence for two classes of chromatin-associated Epstein-Barr virus-determined nuclear antigen.

A new class of Epstein-Barr virus nuclear antigen (EBNA) was identified by the complement fixation assay. This new species of EBNA is more tightly bound to chromatin and was termed class II EBNA, as opposed to the more weakly associated species, class I EBNA. Preparations of this new antigen(s) specifically reduced absorption with the titer of anti-EBNA antibodies as determined by the anticomplement immunofluorescence assay. Therefore, the complement fixation antigens (class II EBNA) appear to be related to the classical EBNA (class I EBNA). The class I EBNA was found to focus at the same pH (4.6) as the soluble antigen found in the cytosol. The class II EBNA differed from the class I EBNA with regard to its overall charge, molecular size, antigenicity, and affinity for chromatin. The class II EBNA appeared to be a basic protein, based on its apparent pI of 9.2 and its binding to cation-exchange resins. It differed from histones with regard to its molecular size (molecular weight between 60,000 and 70,000) and its elution from hydroxylapatite chromatography. Steps were taken to prevent proteolysis and artifacts in the immunological assays and in the overall charge estimation of the new antigen by nonspecific basic histone protein-acidic protein interactions. Both class I and class II EBNA were identified by radioimmunoelectrophoresis on two-dimensional polyacrylamide gels with pI values of 5.0 and 8.5, respectively, and a molecular weight range of 60,000 to 70,000 for both. A lower-molecular-weight antigen identified by molecular sieve chromatography appeared to be due to interference by histones in the immunoassays since it was not observed by the two-dimensional gel electrophoresis. Further characterization of this class II EBNA is in progress.

Antigens, Viral↗
PubMed1982

Ultrastructural changes in the small intestine of neonatal calves with enteric colibacillosis.

The small intestines of calves inoculated orally with the enteropathogenic strain of Escherichia coli 0101:K'B41',K99 were examined by electron microscopy at 3, 6, 12, 16, 21, 36, 69, 70 and 72 hours after inoculation. The challenge organism adhered to the mucosa of the distal small intestine from six hours post-inoculation. Bacteria were separated from the microvillous brush border by a gap of 200 to 300 nm in which bacterial fimbriae and the microvillous glycocalyx were seen. Bacteria never were found in epithelial cells but were present in macrophages in the lamina propria from 12 hours. At three and six hours, cytopathic changes were not seen in the small intestine, but from 12 hours epithelial cells on affected villi had blunt and thick microvilli and contained cytoplasmic inclusions. Epithelial cells were seen frequently in the process of extrusion from the villi, either singly, in small groups, or as ribbons of cells. Intervillous bridges, characteristic of villous fusion, were seen frequently from 69 hours.

Animals↗
PubMed1982

Electron microscopic visualisation of the in vitro phagocytosis of group B streptococci by bovine polymorphonuclear leucocytes.

The phagocytosis of group B streptococci by bovine blood polymorphonuclear leucocytes, after 30 minutes at 37 degrees C, was visualised using scanning and transmission electron microscopy. Several polymorphonuclear leucocytes were seen to have phagocytosed more than one bacterium, despite the initial ratio of bacteria to cells being unity. All bacteria within the cells appeared to be viable and some were undergoing multiplication.

Animals↗
PubMed1982

Purification and biologic characterization of a major Epstein Barr virus-induced membrane glycoprotein.

The Epstein Barr virus membrane antigen (MA) complex is composed of three major high m.w. glycoproteins designated gp 300/350, gp 200/250, and gp 85/90. In the experiments reported in this paper, the gp 300/350 glycoprotein was purified from MA-positive extracts prepared from the B-95-8 cell line. This was accomplished by tandem combination of ion-exchange and lectin chromatography. It was routinely possible to purify this glycoprotein 400- 600-fold by this procedure. Sera from animals immunized with gp 300/350 purified by this approach neutralized EBV infectivity and mediated antibody-dependent cellular cytotoxicity (ADCC) demonstrating that both of these important antigenic determinants were expressed on this glycoprotein. The presence of an ADCC determinant on this molecule was further substantiated by the finding that monoclonal antibody to gp 300/350 blocked ADCC mediated by a human ADCC antibody-positive reference serum.

Animals↗
PubMed1982

Distribution of cryptosporidia within the gastrointestinal tract of young calves.

Natural cryptosporidial infection of the gastrointestinal tract was recognised in four young calves by light microscopy and correlated with scanning and transmission electron microscopy in two of the calves. Seven to 10 sites of the small intestine were examined in each calf and cryptosporidia were most numerous in the posterior 50 per cent. None were found in the anterior 20 per cent of the small intestine, the abomasum or the colon, but they were present in the mucosa of the caecum of three calves.

Animals↗
PubMed1981

IgA antibody, antibody-dependent cellular cytotoxicity and prognosis in patients with nasopharyngeal carcinoma.

Immunoglobulin fractions containing antibodies to the Epstein-Barr virus (EBV) were isolated from different sera and tested in the antibody-dependent cellular cytotoxicity (ADCC) assay. All cytotoxic activity resided in the IgG fraction. IgA antibodies were not cytotoxic in this assay against cells expressing the EBV-induced membrane antigen complex. However, IgA antibodies were able to block the IgG-mediated ADCC reaction, indicating that the IgA and IgG antibodies recognized the same EVB-specific antigenic determinants. This was supported by results from radioimmune precipitation experiments. Our findings suggest that low ADCC titers previously identified in the sera of patients with nasopharyngeal carcinoma (NPC) who had a poor prognosis could be due to the blocking activity of IgA antibodies. The results further suggest that IgA antibodies are detrimental to the patient with this disease, if one assumes that ADCC functions in vivo in immunity to this tumor

Antibodies, Viral↗
PubMed1981

Seroepidemiological study of relationships between Epstein-Barr virus and rheumatoid arthritis.

To elucidate the relationship between Epstein-Barr virus (EBV) and rheumatoid arthritis (RA), we measured antibodies to RA-associated nuclear antigen (anti-RANA) and three other EBV-related antigens in the sera of RA patients and controls. Our study groups consisted of 89 patients with definite or classical RA, mean age 56, male/female ratio 47:42; and 53 normal and osteoarthritis controls, mean age 51, male/female ratio 25:28. In addition to anti-RANA, we measured antibodies to viral capsid antigen (anti-VCA), early antigen (anti-EA) and EBV-associated nuclear antigen (anti-EBNA). Anti-RANA was detected in 71% of RA patients but in only 6% of controls. Elevated anti-VCA titers (greater than 1:160) were more common in RA patients than controls, 31% compared with 15%. The geometric mean titer of anti-VCA was significantly higher iun the RA group, 133 compared with 58. Anti-EA was present in 53% of RA patients but only 19% of controls. Anti-EA in elevated titers (greater than 1:20) was present in 26% of RA patients but only 7% of controls. Characterization of the anti-EA antibodies revealed that the RA patients reacted primarily with the diffuse component, whereas the majority of the controls reacted with the restricted component of the EA complex. In contrast, the frequencies, distributions, and geometric mean titers of anti-EBNA were not significantly different between the two groups. Correlative analysis of these antibodies showed highly significant relationships between anti-VCA and anti-EA, and anti-RANA and anti-EBNA in the RA group. These data are compatible with the interpretation that RA patients have either more active EBV infections than controls or an altered regulation of their immune response to this infectious agent.

Antibodies, Viral↗
PubMed1981

The reliability of IgA antibody to Epstein-Barr virus (EBV) capsid antigen as a test for the diagnosis of nasopharyngeal carcinoma (NPC).

Since patients with nasopharyngeal carcinoma were first reported to have elevated levels of IgA antibody to Epstein-Barr virus (EBV) in their sera, workers in a number of countries have studied the possibility that this assay could be used in the diagnosis and monitoring of patients with this disease. In the United States, a collaborative project involving seven centers has been established to investigate the potential value of IgA antibody to EBV viral capsid antigen (VCA) as a clinical tool. In this report, we will summarize the results obtained from three studies: a comparison of EBV serology in three laboratories; a retrospective study of 37 nasopharyngeal carcinoma (NPC) patients and controls, and a prospective study of 126 NPC patients and 683 controls, including 149 patients with other malignancies involving the head and neck. The study of testing comparability in three laboratories demonstrated the feasibility of using this assay in a number of laboratories. The retrospective study confirmed the difference in IgA antibody titers between NPC patients and matched controls. The prospective study showed a relationship between IgA antibody titers and histopathology but not disease stage. IgA antibody titers were elevated more frequently in patients with nonkeratinizing or poorly differentiated types of NPC than for the well-differentiated squamous cell carcinomas. While IgA antibodies to EBV VCA appear to be of value in the early detection and diagnosis of NPC, it is possible that additional serologic tests for immunity to EBV, such as IgG antibody to VCA or early antigen (EA), will improve even further the clinical value of EBV serology in the management of NPC.

Antibodies, Viral↗
PubMed1980

Anti-EBV serologic tests for nasopharyngeal carcinoma.

Sixty-three serum specimens from American patients with nasopharyngeal carcinoma were examined for antibodies to antigens associated with Epstein-Barr virus (EBV) and compared with 98 specimens from patients with other head and neck cancers, 133 from patients with benign head and neck diseases, and 96 from healthy donors. The level of antibody titers to EBV-associated antigens was correlated with nasopharyngeal carcinoma. The anti-EBV profile of elevated antibody titers directed against viral capsid antigen and early antigen was seen in undifferentiated and nonkeratinizing tumors but usually not in squamous cell tumors. Titers tended to rise with large increases in total tumor burden caused by distant metastases, often before clinical evidence of metastases. At the time of diagnosis, antibody-dependent cellular cytotoxicity testing was performed on serum samples from 46 of the patients with nasopharyngeal carcinoma. Pretreatment titers were usually low in patients in whom recurrence developed and were high in most of the patients who had a good response to treatment and have remained free of recurrence.

Adolescent↗