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Biomedical subjects

J Stephen

Publications and source records attributed to J Stephen.

At least 109 records · Page 6Linked to original sources
PubMed1970

Separation of antigens by immunological specificity. Studies on the desorption of homologous antigen from disulphide-linked antibody immunosorbents.

1. Glycine-hydrochloric acid buffer, pH2.2, desorbed (131)I-labelled human serum albumin (100%), lysozyme (100%), ovalbumin (90%), fluorescent ovalbumin (50-60%) and fluorescent human gamma-globulin (20%) from their respective homologous disulphide-linked antibody immunosorbents; reasons are suggested for the low recoveries of the fluorescently labelled proteins. 2. Approx. 40% of the recovered (131)I-labelled human serum albumin and fluorescent ovalbumin was desorbed above pH6.0, but lysozyme was not eluted until the pH was 3.0 or below. 3. In all cases where high recoveries of antigen were obtained, the immunosorbents could be regenerated and recycled at least four times with full retention of specificity and minimal diminution of capacity. 4. The desorbed antigens were unchanged when compared with the original antigens by quantitative precipitin, specificradioactivity, fluorescent and enzymic analyses and by cellulose acetate electrophoresis. 5. Desorption of antigen with a variety of reagents was investigated. These reagents were less satisfactory than glycine-hydrochloric acid.

Antigen-Antibody Reactions↗
PubMed1966

Separation of antigens by immunological specificity: Use of cellulose-linked antibodies as immunosorbents.

1. Immunosorbents were prepared by coupling activated aminocellulose with the gamma-globulin concentrates of antisera prepared against ovalbumin and human serum albumin. 2. The immunosorbents were low in solubility, but high in capacity for homologous antigens. 3. The high specificity of these immunosorbents was demonstrated by their use in fractionating various mixtures of fluorescent ovalbumin, (131)I-labelled human serum albumin, lysozyme and ribonuclease.

Journal Article↗
PubMed1966

Separation of antigens by immunological specificity: Use of disulphide-linked antibodies as immunosorbents.

1. gamma-Globulin concentrates of antisera prepared against ovalbumin and human serum albumin were thiolated and cross-linked to form insoluble polymers. 2. These immunosorbents were of low solubility and of high capacity for homologous antigen. 3. The high specificity of these immunosorbents was demonstrated by fractionation of various binary mixtures of fluorescent ovalbumin, (131)I-labelled human serum albumin, lysozyme and ribonuclease.

Journal Article↗
PubMedDate not supplied

Prognostic significance of karyotype analysis in children with acute lymphoblastic leukemia.

Chromosome studies, using bone marrow samples of 26 pretreated children (below 15 years of age) with Acute Lymphoblastic Leukemia were carried out to explore the potentialities of applying chromosomal findings as a prognostic indicator in these patients. Abnormal karyotype was identified in 15 patients (57.6 per cent). The chromosomes frequently involved in non-random numerical abnormalities were Nos. 8, 18 and 21. Structural chromosome changes observed consisted of deletion 6q- and translocation t (4;11). After karyotype analysis, patients were grouped into subsets on the basis of the karyotype pattern observed. They were followed up to evaluate their prognosis and survival period. Patients showing hyperdiploid clone with greater than 51 chromosomes had the best prognosis. Patients with normal karyotype and patients with deletion of the long arm of chromosome 6 showed intermediate prognosis whereas patients showing t (4;11), trisomy 8, trisomy 18, trisomy 21, and hypodiploid karyotype were associated with worst prognosis. Thus, karyotype analysis before treatment helps to classify ALL patients as poor, intermediate and good prognosis groups and on this basis therapy can be designed accordingly.

Adolescent↗
PubMedDate not supplied

An electron microscopic investigation of time-related changes in the intestine of neonatal mice infected with murine rotavirus.

Seven-day-old mice were infected orally with murine rotavirus (EDIM) and regions of the gut examined at 24 h intervals up to 7 days by electron microscopy. Structural changes were correlated with data on viral antigen production, thymidine kinase activity, and clinical signs of diarrhea. No pathological changes were detected in the colon. Infection and structural damage were confined to the small intestine, with middle regions showing the most pronounced changes. Constriction of villus bases, edema of the lamina propria, and vacuolation of enterocytes occurred at 24 h postinfection (PI), i.e., before evidence of major virus replication. Transient villus atrophy occurred at 48 h PI. Recovery of villus length was evident by 72 h PI accompanied by evidence of marked enterocyte replication at villus bases. Many enterocytes were damaged with little evidence for the presence of virus particles. By 96 h PI, villi had almost recovered from infection although some enterocytes were still damaged; no virus particles were detected in these cells. A second phase of villus damage and edema of the lamina propria occurred at 120 h PI; the pathology resembled that at 24-48 h PI. By 144 to 168 h PI, recovery of the mucosa from infection was virtually complete. We suggest that many of the pathological features following rotavirus infection result from rotavirus-induced ischemia of villi and that diarrhea results from malabsorption of fluid by damaged villi and hypersecretion of ions released from increased numbers of dividing cells at villus-crypt borders.

Animals↗
PubMedDate not supplied

Intestinal enzyme profiles in normal and rotavirus-infected mice.

To investigate further the pathophysiology of rotavirus-induced diarrhea, changes in specific activities of eight relevant intestinal enzymes [alkaline phosphatase, thymidine kinase, lactase, maltase, sucrase, Na+,K+-adenosine triphosphatase (ATPase), adenylate and guanylate cyclases] were measured following infection of suckling mice with murine rotavirus (epizootic diarrhea of infant mouse strain) and compared with age-matched control mice. The concentration of lactose within the lumen of the gastrointestinal tract during infection was also measured. During the course of infection, activities of alkaline phosphatase and lactase decreased, whilst the activity of thymidine kinase increased. Precocious maturation profiles of sucrase and maltase enzymes were observed. No significant changes were detected in the activities of Na+,K+-ATPase or the adenylate and guanylate cyclases. These results are discussed in relation to existing and novel hypotheses on the pathogenesis of rotavirus-induced diarrhea.

Alkaline Phosphatase↗
PubMedDate not supplied

Application of in vitro autoradiography for monitoring drug response in cancer chemotherapy.

Primary cultures of human breast carcinoma cells were treated for 24 hours with different concentrations of anticancer drugs followed by labelling with 3H-thymidine and 3H-uridine and subsequent autoradiographic processing to study the effect of drugs on nucleic acid synthesis in these cells. 3H-uridine autoradiography was more sensitive than 3H-thymidine autoradiography in the assessment of lethal effects. The results showed that individual neoplasms varied in drug response. This method may be useful for predicting the effectiveness of drugs for treatment of individual cases and also for screening new drugs for anticancer activity.

Antineoplastic Agents↗