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Biomedical subjects

G R Pearson

Publications and source records attributed to G R Pearson.

At least 145 records · Page 8Linked to original sources
PubMed1980

Purification and biochemical characterization of an inhibitor of DNA synthesis produced by an Epstein-Barr virus-transformed B cell line.

An inhibitory factor, which has been shown to suppress the uptake of 125I-iododeoxyuridine by both lymphoid and nonlymphoid cells, was isolated from the supernatant of an Epstein-Barr virus- (EBV) transformed B cell line (1605L) established from a cotton-topped marmoset. Purification of the inhibitor, which was produced in serum-free medium by crowded cultures of the 1605L cells, was achieved by DEAE-cellulose chromatography followed by preparative polyacrylamide gel electrophoresis. The apparent m.w. of the 1605L factor was determined to be 65,000 to 70,000 by SDS-polyacrylamide gel electrophoresis. The inhibitor was sensitive to digestion by trypsin and chymotrypsin but not RNase or DNase, indicating that it was protein in nature. Exposure of the 1605L factor to 56 degrees C for 1/2 hr or pH 2 for 48 hr at 4 degrees C destroyed its inhibitory activity. The biochemical characteristics and activity of the 1605L inhibitor distinguish it from Type I interferon and several other soluble immunologic mediators known to be produced by lymphoid cell lines.

Animals↗
PubMed1980

Inhibitors of DNA synthesis produced by herpesvirus-transformed cell lines.

Inhibitory factors were detected in the supernatant fluids of two herpesvirus-transformed lymphoid cell lines, one a B cell line established from a cotton-topped marmoset with EBV-induced lymphoma (1605L) and the other a HVS-transformed marmoset T cell line (C-1 Ax). The factors produced by both cell lines inhibited the uptake of 125I-iododeoxyuridine (125I-IUDR) by lymphocytes stimulated by both phytohemagglutinin and pokeweed mitogen. Both factors also suppressed the uptake of 125I-IUDR by cells of lymphoid cell lines of both B and T cell origin, indicating that neither factor was specific for lymphoid subpopulations. Furthermore, the factor produced by the 1605L cell line did not exhibit tissue specificity in the target cells that it affected, since it also suppressed 125I-IUDR uptake by the HEp-2 cell line, which is epithelial. Antibody-dependent cellular cytotoxicity, an assay that has been reported to require effector cells capable of protein synthesis but not DNA synthesis, was not suppressed by either factor, indicating that these inhibitors acted at the level of DNA synthesis. Experiments investigating the kinetics of the inhibition of PHA blastogenesis by the 1605L factor suggested that this inhibitor blocked an early stage in the DNA synthetic cycle, since maximum inhibition was observed only when the factor was present early in the culture period.

Animals↗
PubMed1980

Dysentery in pigs associated with cystic enlargement of submucosal glands in the large intestine.

Grossly visible glands were found in the submucosa of the large intestine of five pigs with dysentery. Some were cystic, some were filled with necrotic debris and some had perforated the serosal surface. The mucosa of the large intestine of all pigs had areas of acute catarrhal inflammation with haemorrhage and focal sloughing of the surface epithelium. Although very distinctive and analogous in most respects to collitis cystica profunda, it was felt that the cystic and hypertrophic glands were a secondary finding and represented involvement of glandular elements present in normal animals. Anaerobic vibrio were recovered from three pigs, but the significance of these isolates is unknown.

Animals↗
PubMed1979

Epstein-Barr virus-specific antibody-dependent cellular cytotoxicity in patients with Burkitt's lymphoma.

Coded sera from 54 patients with African Burkitt's lymphoma (BL) were titrated for antibodies against an Epstein-Barr virus (EBV)-induced membrane antigen in the antibody-dependent cellular cytotoxicity (ADCC) assay. The titers were then correlated with the progression of lymphoma growth following chemotherapy. In 74% of the patients with high ADCC titers (greater than 3,840), lymphomas showed partial or complete regression following therapy. In the medium-titered group (240-3,840), 36% of the lymphomas showed some response to therapy, while only 29% of the lymphomas in the low group (less than 240) responded to treatment. These preliminary results indicated that, as previously reported for patients with nasopharyngeal carcinoma, ADCC titers may be a prognotic value in patients with this EBV-associated disease. In an attempt to determine the identity of the ADCC antigen, some of these sera were examined for antibody to the four major MA components so far identified in the membrane of EBV-infected Raji cells. Sera with high ADCC titers in general contained antibody to the four major MA components, while low-titered sera usually contained antibody to three or less of these proteins. There were exceptions to this pattern, however, indicating that the ADCC antigen might differ from the four EBV-induced membrane components so far identified.

Antibodies, Viral↗
PubMed1979

The pathogenesis of enteric colibacillosis in neonatal unsuckled calves.

The development of pathological lesions in the small intestine of neonatal calves is described. Seven newborn calves were challenged orally with a known enteropathogenic strain of E coli 0101k?(A) and killed at varying times after inoculation. Adhesion of bacteria to the mucosa of the small intestine was observed in all calves. A few organisms were seen in the distal small intestine at three hours after inoculation and thereafter adhesion progressed anteriorly along the intestine in calves killed from six to 36 hours. In these calves pathological changes occurred between six and 12 hours after inoculation. Villi were stunted and thickened and the epithelial surface was irregular. A further calf, anaesthetised from five-and-a-half to 10 hours after inoculation and repeatedly sampled from the distal small intestine, developed similar lesions abruptly at nine hours after inoculation. Villus and crypt lengths in the challenged calves were compared with those in three normal uninoculated control calves.

Animals↗
PubMed1979

Epstein-Barr virus-induced membrane antigens: immunochemical characterization of Triton X-100 solubilized viral membrane antigens from EBV-superinfected Raji cells.

In an attempt to qualitatively identify the membrane antigen (MA) complex induced by Epstein-Barr virus (EBV) infection of lymphoblastoid cells, superinfected Raji cells were surface labelled with 125I by the lactoperoxidase method and solubilized with Triton X-100, then the 125I-labelled membrane proteins were precipitated by sera containing high antibody titers to MA. Analysis of these immune precipitates on sodium dodecyl sulfate polyacrylamide gel eletrophoresis identified four major EBV-specific membrane proteins with molecular weights (mol. wt) of 280,000, 250,000, 170,000 and 90,000. Sera from patients with Burkitt's lymphoma (BL), nasopharyngeal carcinoma (NPC) and infectious mononucleosis (IM) and from EBV-infected disease-free individuals showed differential patterns of reactivity to these antigens with some sera only recognizing three or less of the antigens. The results from invesigations with these sera also indicated that these major proteins were not related to EBV-induced viral capsid antigens (VCA) or the virus-associated early antigen (EA) complexes as defined by immunofluorescence. Metabolic labelling of EBV-infected Raji cells with [14C]glucosamine, followed by Triton X-100 solubilization and radioimmune precipitation, identified the 280,000, 250,000 and 90,000 components as glycoproteins. The lactoperoxidase-labelled 170,000 molecular weight component was not significantly glycosylated and, therefore, could not be categorized as a glycoprotein on the basis of this study. In addition, a glycoprotein with a mol. wt of 130,000 was identified by this approach which also appeared to be specified by EBV. The results from these investigations, therefore, indicated that the EBV-induced MA complex was composed of four major glycoproteins and one nonglycosylated high mol. wt protein.

Antigens, Surface↗
PubMed1979

Quantitative observations on experimental reo-like virus (rotavirus) infection in colostrum-deprived calves.

Ten calves were challenged with one of two strains of reo-like virus (rotavirus). Changes in the daily faecal and urinary outputs were monitored and packed cell volume, plasma sodium, potassium and urea levels were measured. Faeces were examined for the presence of rotavirus by direct electron microscopy and immunofluorescence in cultures of PK(15) cells. All calves excreted rotavirus in the faeces for several days. Two calves remained clinically normal throughout the experiment, but in the remaining calves, faeces became mucoid in consistency and yellow-white in colour. In only two calves did the daily faecal output exceed 500 g with a fall in the dry matter content to less than 10 per cent. Slightly elevated blood urea levels and hyperkalaemia were the only changes observed in blood chemistry and these quickly returned to normal. Virus antigen was observed in the epithelial cells by immunofluorescence in the proximal and middle small intestine of calves. Pathological lesions occurred predominantly in the proximal small intestine of nine calves examined.

Animals↗
PubMed1979

Ultrastructural changes in small intestinal epithelium of neonatal pigs infected with pig rotavirus.

The small intestine of piglets orally infected with rotavirus was examined by electron microscopy 18, 24, 48 and 60 hours after infection. At 18 and 24 hours after infection columnar epithelial cells covered the villi. Infected epithelial cells tended to be less electron-dense than uninfected cells and were more numerous at 24 hours after infection. Two types of rotavirus particle were seen, usually within dilated cisternae of the RER: non-enveloped particles measuring 50 to 60 nm and enveloped particles measuring 65 to 75 nm. Non-membrane bound viroplasm containing electron-dense cores was encountered outside the cisternae 18 and 24 hours after infection. Tubular structures measuring 44 to 56 nm were often found in nuclei of infected cells. Single-membraned (44 to 55 nm) and double-membraned tubules (70 to 80 nm) associated with viral manufacture were found in the cytoplasm of infected cells. At 48 and 60 hours after infection a proportion of villous epithelial cells were cuboidal. Virus particles were detected in only a few epithelial cells and nuclear and cytoplasmic tubules were not seen. At all times after infection some infected cells showed a reduction in the number and size of the microvilli comprising the brush border.

Animals↗
PubMed1978

Antibody-dependent cellular cytotoxicity against Epstein-Barr virus-associated antigens in African patients with nasopharyngeal carcinoma.

Antibody-dependent cellular cytotoxicity (ADCC) was performed on serum samples from African patients with nasopharyngeal carcinoma (NPC) to determine whether antibody titers determined by this assay might be of prognostic value in this disease. The serum donors were divided into two groups: (1) those individuals who died within 2 years following diagnosis of NPC; and (2) individuals who responded well to therapy and surivived for more than 2 years following diagnosis. The ADCC GMT for the survivor group was significantly higher than the GMT for non-survivors (%5,410 versus 615). Interestingly, there were a number of discordant sera in the non-survivor group that had very low ADCC titers (less than 240) at diagnosis in the presence of high VCA titers. When ADCC titers were compared with anti-EA or IgA antibody titers to VCA, a statistically significant inverse correlation was noted. These data suggest that ADCC titers might be of prognostic importance in African NPC.

Africa↗
PubMed1978

Pathological changes in the small intestine of neonatal calves naturally infected with reo-like virus (rotavirus).

Nine calves, of which six had been challenged with an enteropathogenic strain of Escherichia coli, were found to be naturally infected with rotavirus. Rotavirus was recovered from the faeces of six calves and rotavirus antigen was detected in the intestinal mucosa of all calves. Stunting and fusion of villi were seen principally in the proximal and middle small intestine, where rotavirus antigen was detected by immunofluorescence. Typical lesions of enteric colibacillosis were found in the distal ileum of the challenged calves, associated with adhesion of the challenge strain of E coli to the mucosa. All samples were removed from the intestine under general anaesthesia and denudation of villi was not observed. However, following exsanguination and resampling at the same site in the small intestine of one calf, denudation was a constant feature.

Animals↗
PubMed1978

Epstein-Barr virus-associated antigens in nasopharyngeal carcinoma.

Thirty-five sera from American patients with nasopharyngeal carcinoma were examined for Epstein-Barr virus (EBV)-associated antigens and compared with 85 sera from patients with other head and neck cancers, 80 sera from patients with lymphoma, and 47 sera from healthy control subjects. There was a definite correlation between the presence of nasopharyngeal carcinoma and the level of antibody titers to EBV. In particular, two tests that detected antibody to early antigen and antibody to viral capsid antigen in the serum IgA fraction were highly specific for the presence of nasopharyngeal carcinoma. There was a significant decrease in these antibody titers with clinical remission of the disease in treated patients with nasopharyngeal carcinoma. Clinically, these tests should have important application in the management and follow-up of patients with nasopharyngeal carcinoma.

Antigens, Viral↗
PubMed1978

An immunologic basis for detection of occult primary malignancies of the head and neck.

After extensive evaluation of patients with metastatic neck disease and clinically undetectable primary cancer of the head and neck, the clinician is often faced with the difficult question of subsequent management. In this study, sera from 11 patients with clinically occult carcinoma and metastatic lymphadenopathy were studied for Epstein-Barr virus-associated antigens. These were compared with 35 sera from patients with known nasopharyngeal carcinoma at all stages of disease and treatment and with 212 sera from control patients with other head and neck tumors, patients with lymphoma, and normal controls. There was a significant correlation between high antibody titers to Epstein-Barr virus, especially in the serum IgA fraction, and the presence of nasopharyngeal carcinoma. Thus, identification of occult nasopharyngeal carcinoma by immunologic means may have important application in the selective management of the patient with an unknown head and neck primary malignancy.

Antibodies, Viral↗