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Biomedical subjects

L Visser

Publications and source records attributed to L Visser.

At least 55 records · Page 3Linked to original sources
PubMed1993

Characterization of the alkaline phosphatase expressed on the surface of a Hodgkin's lymphoma cell line.

Alkaline phosphatase solubilized from a human Hodgkin's lymphoma cell line (L428) was compared with purified amphiphilic and hydrophilic forms of the enzyme from human liver, and with the enzyme solubilized from a cultured osteosarcoma cell line (Saos-2). Purified hydrophilic alkaline phosphatases from human placenta and intestine were also compared in some experiments. Alkaline phosphatase was released from the plasma membrane of intact lymphocytes by phosphatidylinositol phospholipase C and thus is anchored to the outside of the plasma membrane by covalently attached phosphatidylinositol. Enzyme released in this way was hydrophilic and that solubilized with Triton X-100 was amphiphilic, as assessed by adsorption to octyl-Sepharose. Lymphocyte alkaline phosphatase, when released from the membrane by phosphatidylinositol phospholipase C or solubilized by Triton X-100, had apparent M(r) values on gradient gel electrophoresis of 227 and 494 kDa, respectively. These values were consistently higher than equivalent ones obtained with enzymes purified from human liver, but were similar to those of cultured osteosarcoma cells. Isoenzyme-specific inhibitors of alkaline phosphatase showed similar patterns of inhibition between the enzyme from L428 cells and the tissue-nonspecific (liver/kidney/bone) isoenzyme from human liver. Heat stabilities were similar for the enzymes from L428 and Saos-2 (bone isoform) cell lines, but differed significantly from those of liver, intestine and placenta. We conclude that the alkaline phosphatase expressed in this lymphoma cell line (L428) has properties that most closely resemble those of the tissue-nonspecific isoenzyme found normally in osteoblasts of bone (bone isoform).

Alkaline Phosphatase↗
PubMed1992

Spontaneous hybridoma formation induced by immunization with Haemophilus paragallinarum: evidence for a lipopolysaccharide fusion inducer.

The phenomenon of spontaneous fusion between myeloma cells and splenocytes from mice immunized with formalin-inactivated Haemophilus paragallinarum cells, has been reported on recently (1). The identity and properties of the bacterial inducer of fusogenicity of splenocytes have been further investigated with the aid of a monoclonal antibody VF3 against H. paragallinarum (2), which has a bacterial strain specificity correlating with the ability of the strains to induce spontaneous fusion between splenocytes of immunized mice and myeloma cells. It was shown that the lipopolysaccharide fraction of the bacteria was required for the induction of fusogenicity. LPS involvement was clearly indicated by the parallel effects on VF3 antigenicity and fusogenic inductivity of various treatments such as proteolytic digestion, periodate oxidation and sensitivity towards alkali, acid or freezing.

Animals↗
PubMed1992

Biology of Hodgkin's disease.

The biology of Hodgkin's disease is one of the most intriguing subjects in lymphoma research. The presence of only a small proportion of neoplastic cells and a vast majority of reactive cells reflects the presence of complex interactions between these cell types. In this paper we discuss findings indicating that Reed-Sternberg cells may be virally transformed cells that have evaded a cytotoxic immune response and induce an ineffective delayed type hypersensitivity reaction.

Cell Transformation, Viral↗
PubMed1992

Reactivity of monoclonal antibody B-ly7 with a subset of activated T cells and T-cell lymphomas.

Antibody B-ly7 is reactive with hairy cell leukemia and a small subpopulation of normal lymphocytes. The B-ly7 antigen can also be induced on normal peripheral blood lymphocytes by phorbol ester stimulation. Recently it has been found that the reactivity pattern of B-ly7 is similar to that of HML-1, an antibody reactive with mucosal T lymphocytes and so called enteropathy associated T-cell lymphomas. Reactivity of B-ly7 with 6/61 peripheral T-cell lymphomas, including two intestinal and four extraintestinal cases, is described. The intestinal cases were CD8 and CD7 positive, whereas the extraintestinal cases were CD4 positive and CD7 negative. Activation of purified peripheral blood T cells resulted in approximately 20% B-ly7+ T cells at Day 3. Approximately 75% of the B-ly7+ cells were CD8+, whereas the remainder were CD4+. The results indicate that B-ly7 as well as HML-1 recognize an activation-associated antigen that is expressed on small normal T-cell and B-cell populations and can be induced on a relatively high proportion of T and B cells in vitro.

Adult↗
PubMed1991

Antibody MT3 is reactive with a novel exon B-associated 190-kDa sialic acid-dependent epitope of the leukocyte common antigen complex.

MT3 is a new antibody reactive with a restricted isoform of the leukocyte common Ag (CD45) family. The Ag is mainly expressed on T lymphocytes and thymocytes. It is differentially expressed on B cell subpopulations, with no staining of the majority of small follicular mantle zone B cells but positive staining of the majority of marginal zone B cells of spleen. Like most CD45 antibodies, reactivity can be demonstrated in fresh frozen as well as in formalin-fixed, paraffin-embedded tissues. This reactivity clearly differs from all other published anti-CD45 antibodies. In immunoprecipitation and Western blot procedures, the antibody reacts with a major band with a molecular mass of 190 kDa and weak bands with molecular masses of 205 and 220 kDa. Compared to antibody PD7 that reacts with exon B-encoded sequences, the reactivity with the 205 and 220 bands is much weaker. This is reflected in MT3 reactivity with leukocyte common Ag transfectants that include exon B-encoded sequences, such as AB and B, but not with those that also include C-encoded sequences, such as ABC or BC. It can be concluded that MT3 recognizes additional heterogeneity in the leukocyte common Ag complex, that is based on the differential expression of sialic acid-dependent determinants associated with exon B-encoded sequences.

Antibodies, Monoclonal↗
PubMed1991

Vaginal delivery after previous cesarean section in a rural West African hospital.

Two hundred twenty women with prior cesarean section were delivered at our institution between January 1987 and February 1990. Vaginal delivery was achieved in 111 (66%) of 169 patients given a trial of labor (TOL). Success of TOL correlated positively with the number of prior vaginal deliveries (P less than 0.05) and inversely with the number of prior cesarean sections (P less than 0.005). Maternal and fetal outcome were not significantly different between the TOL and non-TOL groups.

Female↗
PubMed1991

Small lymphocytic lymphomas with predominant splenomegaly: a comparison of immunophenotypes with cases of predominant lymphadenopathy.

In this study, we compared small lymphocytic lymphomas with predominant lymphadenopathy with those with predominant splenomegaly and found differences in morphology and immunophenotype as well as clinical features. Cases with lymphadenopathy were characterized by widespread disease, CLL type morphology with proliferation centers, and a CD5, CD11c, CD23, CD43 positive, CD45Ro negative immunophenotype. Cases with predominant splenomegaly had more localized disease, a mantle zone pattern or a diffuse growth pattern without proliferation centers, and a CD5, CD11c, CD23, CD43 negative, and sometimes CD45Ro positive immunophenotype. CD45Ro (UCHL1) positivity and alkaline phosphatase staining were associated with a mantle zone growth pattern. Comparison with other small lymphocytic lymphoma subtypes indicated that each has its own specific immunophenotype.

Aged↗
PubMed1991

HML-1 antigen on mucosa-associated T cells, activated cells, and hairy leukemic cells is a new integrin containing the beta 7 subunit.

The monoclonal antibodies HML-1, B-ly7 and Ber-ACT8 recognize intramucosal gut T lymphocytes, activated cells, and hairy cell leukemia. The antigen on hairy cells consists of three glycoproteins (160 kappa D, 130 kappa D and 105 kappa D unreduced; 145 kappa D and 120 kappa D reduced). These peptides have biochemical features reminiscent of integrins but we have shown by immunoprecipitation that they are not known integrin subunits. We have used a newly produced antibody (BP6) to purify this molecule and shown by N-terminal sequence analysis that the smallest subunit is the product of integrin beta 7 cDNA. This molecule is thus a new member of the integrin family of leucocyte adhesion proteins. Immunoprecipitation experiments indicate that the two larger subunits are recognized by HML-1, B-ly7 and Ber-ACT8.

Amino Acid Sequence↗
PubMed1991

Tissue distribution of restricted leukocyte common antigens. A comprehensive study with protein- and carbohydrate-specific CD45R antibodies.

A panel of monoclonal antibodies, specific for either protein or carbohydrate components of the leukocyte common antigen (LCA), were used to characterize the expression pattern of different variants of this antigen complex. Immunohistochemical and flow cytometric analysis was carried out on human lymphoid tissues from different anatomical compartments. We found that variations in terminal sialic acid or O-linked sugar moieties were associated with drastic differences in reactivity with some of the CD45R antibodies. For example, the carbohydrate determinants recognized by MT2 (CD45RA) and 2B11 (CD45) were not or were very weakly expressed on germinal center cells, whereas the carbohydrate determinant recognized by MT3 (CD45RB) was not expressed on the majority of mantle zone B cells. On the other hand, KiB3 (CD45RA) reacted with a protein determinant that is normally only exposed on mantle zone B cells but can be uncovered on marginal zone B cells and the CD45RA-positive T-cell subpopulation by enzymatic treatment. The findings suggest that differential biosynthesis and expression of the carbohydrate components of LCA are important mechanisms to generate additional LCA heterogeneity. Similar to the differential usage of the variable region, the exact carbohydrate composition is also linked to the stage of cell development. Heterogeneity in carbohydrate composition of the extracellular domain of LCA appears to enable interactions with different ligands, thereby holding the key to the regulation of LCA cytoplasmic tyrosine phosphatase activity.

Antibodies↗
PubMed1991

Monoclonal antibody OPD4 is reactive with CD45RO, but differs from UCHL1 by the absence of monocyte reactivity.

Monoclonal antibody OPD4 was described as a novel monoclonal antibody recognizing a helper/inducer T-cell subset in paraffin-tissue sections. The authors have analyzed this reagent with respect to its molecular weight, reactivity with leukocyte common antigen (LCA) transfectants and cell and tissue distribution. OPD4 was found to be reactive with the 180 kd molecular weight isoform of the leukocyte common antigen family, similar to antibody UCHL1 and therefore can be considered as a CD45RO reagent. The only difference in distribution was found to be the absence of OPD4 reactivity with peripheral blood monocytes. Since OPD4 recognizes the same antigen on T cells as UCHL1, both reagents do not need applied in the immunophenotyping of lymphomas.

Animals↗
PubMed1991

Alcohol on the television and in viewers' experience.

This study explores television viewers' perceptions of the portrayal of alcohol use in prime-time television programmes, and viewers' attitude toward alcohol use in real life. The actual incidence of the portrayal of alcohol use on television during the same period of the survey was also taken into consideration. These perceptions and attitudes were scrutinized for factors of risk in terms of the development of alcohol-related problems in South Africa with a view to assisting preventive agents in devising rational and timeous preventive programmes.

Adolescent↗
PubMed1991

Drug abuse: consequences in terms of family pathology and disintegration.

This article examines some of the consequences of drug addiction in terms of family pathology and family disintegration. It briefly elucidates the role of the family in developing and maintaining drug addiction in family members. The concept of 'secondary' sufferers of the illness of drug addiction is examined. An actual case history will be presented in order to facilitate analysis of some of the forms of pathology and disintegration so often seen in the family of the drug addict. Within the family context, the question of who, if anyone, is the victim of drug addiction, is raised.

Adult↗
PubMed1990

B-ly-7, a monoclonal antibody reactive with hairy cell leukemia, also defines an activation antigen on normal CD8+ T cells.

We undertook a study to determine the specificity of the monoclonal antibody, B-ly-7, for hairy cell leukemia (HCL) by examining the expression in 150 samples from B-cell lymphoproliferative diseases as well as screening for reactivity in a number of other hematologic malignancies. Within the B-cell lineage we found that the expression of B-ly-7 was highly specific for HCL and reacted with all 28 cases examined, as well as with 3 of 9 cases of a variant form of HCL. Cells of other closely related B-cell disorders, prolymphocytic leukemia, and splenic lymphoma with villous lymphocytes were negative. Investigation of the peripheral blood and bone marrow of patients with HCL before and after treatment with alpha-interferon or deoxycoformycin suggests that B-ly-7 may be useful in the assessment of minimal disease after therapy. In addition to HCL, we found that B-ly-7 was positive with cells of three mature, CD4+ T-cell malignancies. In view of the reactivity with malignancies of activated B and T cells, we searched for the expression of B-ly-7 on activated, normal B and T cells and found that B-ly-7 reacted specifically with activated normal peripheral blood CD8+ T cells. B-ly-7 has a number of applications, including the precise classification of mature B-cell neoplasia and the diagnosis HCL and its assessment after treatment. In addition, B-ly-7 recognizes a small subset of T-cell disorders. Its expression on these malignancies and on in vitro activated peripheral blood CD8+ T cells suggests that B-ly-7 detects a lymphocyte activation antigen.

Antibodies, Monoclonal↗
PubMed1990

Purification and characterization of a novel heparinase.

A unique heparinase was isolated from a recently discovered Gram-negative soil bacterium. The enzyme (heparinase III) was purified by hydroxylapatite chromatography, chromatofocusing, and gel permeation chromatography. The enrichment was 48x, and the specific activity of catalytically pure heparinase was 127 IU/mg of protein. Similar to the heparinase I from Flavobacterium heparinum, heparinase III also degrades heparin to mainly disaccharide fragments. It is specific for heparin and also breaks down heparan sulfate, but not hyaluronic acid and chondroitin sulfate. Heparinase III, however, differs markedly from heparinase I in several other aspects: it has a higher molecular mass (94 versus 43 kDa), pI (9.2 versus 8.5), its Km and kcat are different, and it has a higher energy of activation (15.6 versus 6.3 kcal/mol). Optimal activity was also found at higher pH (7.6 versus 6.5) and temperature (45 versus 37 degrees C). Furthermore, the amino acid composition of heparinase III is quite different from that of heparinase I.

Amino Acids↗
PubMed1990

Haptenated nylon-coated polystyrene plates as a solid phase for ELISA.

An ELISA system, based on the novel use of a hapten-nylon conjugate as solid-phase coating antigen, has been applied in the screening of hybridoma cultures for anti-hapten monoclonal antibodies directed against the herbicide atrazine and its derivatives. Conjugation of a 2-aminocaproic acid derivative of atrazine with DCC to polyamide (Nylon 6) gave haptenated nylon which was soluble in aqueous cresol-ethanol mixtures and adsorbed efficiently on polystyrene microtitre plates. Reproducible ELISA results were obtained with culture supernatants of hybridomas derived from spleen cells of mice that had been immunized with atrazine-bovine serum albumin conjugates. Satisfactory results were also obtained with a water soluble peptide conjugated to nylon for use as a coating antigen in an ELISA. Plates coated with hapten-nylon as antigen have the added advantage that they can be stored at room temperature for at least 6 months without loss of activity. Nylon therefore appears to have general applicability as a carrier for both non-polar and polar haptens in the preparation and use of coating antigens.

Adsorption↗
PubMed1990

Purification of soluble enzymes from erythrocyte hemolysates by three phase partitioning.

1. The three phase partitioning method of protein fractionation was successfully applied to human erythrocyte hemolysates for the removal of hemoglobin and the concentration of soluble enzymes. 2. Human carbonic anhydrase I and II, catalase and superoxide dismutase were recovered free of hemoglobin and in good yield in the initial partitioning step, with a 60- to 80-fold enrichment of enzyme activities. 3. After further purification, carbonic anhydrases I and II were obtained at overall yields of 84 and 29%, respectively, crystallized catalase at 38% and superoxide dismutase at 52%.

Carbonic Anhydrases↗