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Biomedical subjects

L Visser

Publications and source records attributed to L Visser.

At least 73 records · Page 4Linked to original sources
PubMed1990

Spontaneous fusion between splenocytes and myeloma cells induced by bacterial immunization.

Spontaneous fusion between lymphoid and carcinoma cells in vivo has been described previously. Splenocytes from mice treated with LPS or mitogen have been reported to fuse better with myeloma cells using PEG as fusion agent than splenocytes from untreated mice. We report a phenomenon where immunization of mice with formalin treated, whole Haemophilus paragallinarum bacteria induced spontaneous fusion of splenocytes with myeloma cells in vitro, without the aid of any fusion agent. Co-immunization of mice with H. paragallinarum and an unrelated antigen (hen's egg white lysozyme), followed by co-culturing of the immune splenocytes with SP2/0 myeloma cells, yielded stable hybridoma cell lines producing anti-lysozyme antibodies. H. paragallinarum may be used in adjuvants to simplify the production of monoclonal antibodies, and the discovery of a promotional activity of a gram negative bacterium on cell fusion and hybridoma formation may shed new light on spontaneous fusion as a natural immune phenomenon in cancer.

Animals↗
PubMed1990

Induction of B-cell chronic lymphocytic leukaemia and hairy cell leukaemia like phenotypes by phorbol ester treatment of normal peripheral blood B-cells.

To investigate the relationship between normal B-cells, B-cell chronic lymphocytic leukaemia (B-CLL) cells and hairy cell leukaemia (HCL) cells the three cell types were incubated with phorbol myristic acetate (PMA). The parameters studied were morphology, immunophenotype and tartrate resistant acid phosphatase (TRAP). PMA stimulation of B-cells induced morphological changes as well as CD5, CD11c, B-ly 7 and TRAP positivity. The cells formed small aggregates, the cell membranes were ruffled and frequently hairy and a small number of cells became plastic adherent and developed dendritic structure. CD5 and CD11c appeared on day 2, imitating a B-CLL phenotype. On day 3 and 4 a decrease of CD5, an increase of CD11c and the appearance of B-ly 7 could be seen mimicking an HCL phenotype. The changes in B-CLL and HCL upon PMA stimulation were mainly morphological: the B-CLL cells became ruffled and aggregated strongly, while the HCL cells developed dendritic features and became adherent. The immunophenotype of the PMA stimulated HCL cells did not change. The B-CLL cells remained CD5 positive and did not become B-ly 7 positive. The findings indicate that although PMA stimulation of normal peripheral blood cells results in CLL- as well as HCL-like phenotypes, similar stimulation of B-CLL cells does not result in an HCL-like phenotype.

B-Lymphocytes↗
PubMed1990

The detection and isolation of a paralysis toxin present in Argas (Persicargas) walkerae.

One-day-old leghorn chickens were used in a laboratory assay to determine the toxicity of crude extracts of the tick Argas (Persicargas) walkerae and of fractions obtained during the isolation procedure. Extracts of unfed and engorged larvae, nymphae and females were tested using this in vivo test system. Only extracts of replete A. (P.) walkerae larvae produced paralysis. A toxic fraction was isolated from replete larval extracts by gel-permeation and ion-exchange chromatography. This fraction with a pI of 4,5, showed 2 major bands corresponding to a Mr of 32 kDa and 60 kDa after SDS-polyacrylamide gel electrophoresis.

Animals↗
PubMed1989

Monoclonal antibodies reactive with hairy cell leukemia.

Monoclonal antibodies reactive with hairy cell leukemia were developed to aid in the diagnosis of this subtype of B cell chronic lymphocytic leukemia and to gain better insight into the origin of hairy cells. Three antibodies were found to be of value in the diagnosis of hairy cell leukemia. Antibody B-ly 2 can be considered a pan-B cell reagent and generally reacts similar to CD22 antibodies. Antibody B-ly 6 is reactive with the same antigen as CD11c (p150/95), an antigen that is present on hairy cell leukemia, macrophages, and a minor subpopulation of lymphocytes. Antibody B-ly 7 is a unique antibody reactive with 144 Kd antigen present only on hairy cell leukemia and a very small population of normal B lymphocytes. This subpopulation may be the counterpart of hairy cells.

Antibodies, Monoclonal↗
PubMed1988

Kinetic properties of toxic protease inhibitors isolated from tick eggs.

1. Egg-toxins from Rhipicephalus evertsi evertsi, Boophilus microplus, Boophilus decoloratus and Hyalomma truncatum were found to be inhibitors of trypsin and in two cases also of chymotrypsin. 2. Fast tight-binding and slow-binding inhibition were observed. 3. Immunological identity of the toxins were assessed with Ouchterlony immunodiffusion and ELISA. 4. The protease content of B. decoloratus and Amblyomma hebraeum tick eggs were determined by a linked enzyme assay. 5. The predictive value of the kinetic constants in inferring a possible physiological role was discussed.

Animals↗
PubMed1988

Isotype restriction of murine antibodies towards the loop region of hen's egg white lysozyme.

Monoclonal antibodies specific for the loop determinant (residues 64-80) of hen's egg white lysozyme demonstrated an immunoglobulin class restriction. Only IgM response against the loop could be evoked in mice, irrespective of whether the immunogen was the intact native lysozyme as such, or the loop peptide covalently conjugated to a synthetic carrier, poly-DL-alanyl-poly-L-lysine (A-L). Despite the fact that in polyclonal antisera from mice immunized with lysozyme, the ELISA-titre of anti-loop reactivity was very low, 26% of the total anti-lysozyme response could be accounted for by the loop when expressed as the percentage of anti-lysozyme hybridoma colonies producing monoclonal antibodies reactive with the loop. The results can be interpreted either as determinant controlled isotype restriction, or alternatively, as an affinity restriction leading to the phenomenon that antibodies of isotypes other than IgM are formed, but are of too low avidity to be detected by the ELISA method.

Animals↗
PubMed1988

Glucose metabolism by Lactobacillus divergens.

Earlier studies on the fermentation of D-[1-14C]- and D-[3,4-14C]glucose by Lactobacillus divergens showed that lactate was the major fermentation product and that it was probably produced by glycolysis. It was therefore recommend that L. divergens be reclassified as a homofermentative organism. In the present investigation, products of D-[1-14C]-,D-[2-14C]- and D-[3,4-14C]glucose fermented by L. divergens were isolated, and their specific radioactivities and the distribution patterns of radioactivity in their C-atoms were determined. The positional labelling patterns of the fermentation products, their specific radioactivities and their concentrations confirmed that glucose is degraded via the glycolytic pathway. Some secondary decarboxylation/dissimilation of pyruvate to acetate, formate and CO2 was also observed. These results provide conclusive proof that L. divergens is indeed a homofermentative organism. Results obtained with D-[U-14C]glucose showed that approximately three-quarters of the lactate but less than 10% each of the formate and acetate were produced from glucose. The remainder was presumably derived to a varying degree from endogenous non-glucose sources such as fructose and/or amino acids.

Acetates↗
PubMed1987

Reversed-phase and hydrophobic-interaction high-performance liquid chromatography of elapid cardiotoxins.

The separation of proteins by hydrophobic-interaction HPLC and reversed-phase HPLC depends upon differences in the hydrophobicity of accessible surface groups. The elution order of a group of snake venom cardiotoxins was found to vary between these two HPLC methods. Circular dichroism spectroscopy showed that the eluant acetonitrile-trifluoroacetic acid used for reversed-phase HPLC altered the conformation of the toxins, whereas the salt-buffer eluting medium used for hydrophobic-interaction HPLC did not affect toxin conformation. The retention times of cardiotoxins on reversed-phase HPLC are therefore influenced by their conformational instability in the eluting medium which causes partial or complete unfolding. Hydrophobic interaction is clearly the preferred method with which to correlate the "surface hydrophobicity" of cardiotoxins and their biological effects.

Animals↗
PubMed1987

Plasma vitamin A, E, C and B6 levels in myocardial infarction.

Vitamin A, E, C and B6 status was studied in 30 patients with myocardial infarction and in 19 age- and sex-matched patients after elective surgery or trauma. Plasma levels of the four vitamins studied were low, remained low or decreased transiently in both groups of patients during the acute catabolic response phase, and began to return to normal after the third day from the start of the catabolic response. These changes in plasma levels are therefore neither of any special pathophysiological importance in nor specific to myocardial infarction.

Adult↗
PubMed1987

Monoclonal antibodies (MT1, MT2, MB1, MB2, MB3) reactive with leukocyte subsets in paraffin-embedded tissue sections.

The absence of reactivity on routinely prepared tissue sections has hampered the use of monoclonal antileukocyte antibodies in diagnostic histopathology. Here we describe five new antibodies reactive with leukocyte subsets in formaldehyde-fixed, paraffin-embedded tissue sections. Antibody MT1 is reactive with mature and immature T cells and not with mature B cells. MT2 is reactive with mature T cells and B cells, but not with immature T cells, activated T cells, and germinal center B cells. Antibody MB1 is reactive with all B cells, with about 50% of mature T cells, and not with immature T cells. MB2 is reactive with all B cells and not with T cells. However, MB2 also stains endothelial cells and several types of epithelial cells. MB3 is reactive with B cells and histiocytes, but not with T cells. The antibodies were tested on a series of lymphomas that were also immunophenotyped with a panel of well-established reagents on frozen tissue sections. The results indicate that the MB and MT antibodies are useful tools in the study of reactive and neoplastic disorders of the lymphoid system.

Antibodies, Monoclonal↗
PubMed1987

Clonal immunoglobulin gene rearrangements in tissues involved by Hodgkin's disease.

The nature of Reed-Sternberg cells, the abnormal cells of Hodgkin's disease, is controversial. Morphological and immunologic marker studies suggested different cells of origin. To investigate a possible B or T cell origin, immunoglobulin and T cell receptor gene analyses were performed on tissues from 11 patients in early and late stages of Hodgkin's disease. In addition, the immunologic marker patterns of the Reed-Sternberg cells were determined. Rearrangements of immunoglobulin heavy- and light-chain genes were detected in tissues from five patients, particularly in late stages of the disease when lymphocyte depletion had occurred. No rearrangements of T cell receptor genes were found. The results indicate that clonal immunoglobulin gene rearrangements can be detected in tissues involved by Hodgkin's disease.

Adolescent↗
PubMed1986

Biochemical vitamin E deficiency in chronic pancreatitis.

In order to study the frequency of biochemical vitamin E deficiency in chronic alcohol-induced pancreatitis, we measured plasma vitamin E and total blood lipids in 44 patients with chronic pancreatitis and 83 control subjects (44 normal controls; 39 Crohn's disease controls). Mean plasma vitamin E and mean ratio vitamin E/total blood lipids, a more sensitive indicator of vitamin E status, were significantly lower in chronic pancreatitis when compared with either control group. A low vitamin E/total lipids ratio was found in 75% of patients with pancreatitis. Within the chronic pancreatitis group, mean plasma vitamin E and the ratio vitamin E to total lipids were significantly lower in those with steatorrhoea (23 patients--pancreatic steatorrhoea subgroup) than in those without (21 patients--pancreatic non-steatorrhoea subgroup). 91% of the pancreatic steatorrhoea subgroup had a low vitamin E/total lipids ratio. However, patients without pancreatic steatorrhoea also had significantly lower levels of plasma vitamin E and the ratio vitamin E/total lipids when compared to controls. We conclude that biochemical vitamin E deficiency is common in chronic alcohol-induced pancreatitis, particularly in patients with steatorrhoea, and that factors other than fat malabsorption may be responsible for vitamin E deficiency in pancreatic non-steatorrhoea.

Adolescent↗
PubMed1986

Isolation of Cowdria ruminantium by means of Percoll density gradient centrifugation and detection by an enzyme-linked immunosorbent assay.

The isolation of Cowdria ruminantium by means of Percoll density gradient centrifugation permits the recovery of partially purified viable populations of the organism possessing distinctly different densities. These conclusions are based upon results of analyses of density fractions by intravenous inoculation into sheep, protein determination, electron microscopy and enzyme-linked immunosorbent assay. Morphological differences were observed in the density fractions obtained from infected brain tissue and Amblyomma hebraeum nymphae.

Animals↗
PubMed1986

Nodular lymphocyte predominance type of Hodgkin's disease is a germinal center lymphoma.

Nodular lymphocyte predominance type of Hodgkin's disease can be distinguished from other subtypes of Hodgkin's disease on morphological and clinical grounds. Immunohistological studies on frozen tissue sections of seven cases of nodular lymphocyte predominance type of Hodgkin's disease (NLPHD) show differences in B cell, T cell, as well as dendritic cell population. NLPHD is confined to follicles which contain predominantly small lymphocytes, usually over 50% B cells and large numbers of B2+, anti-C3b+, anti-DRC+, and Ig- dendritic cells. The IgM+, IgD+, Leu8- B lymphocytes are of polyclonal origin. The T lymphocytes in these follicles are reactive with Leu7 in addition to T11, Leu1, T3, Leu3, and WT1. Leu7 is a monoclonal antibody reactive with natural killer cells, but also with a subpopulation of Leu3+ lymphocytes present in normal germinal centers. The population with this phenotype, not found in other types of Hodgkin's disease, appears to be greatly increased (up to 30%) in NLPHD. The so-called L&H type Sternberg-Reed (S-R) cells of NLPHD are transformed B cells, reactive with anti-B cell monoclonal antibodies which in some cases express detectable amounts of membrane and/or cytoplasmic immunoglobulin. Also, L&H type Sternberg-Reed cells in all cases stained for Ki-1 and Tac, and in three cases for LeuM1. Taken together, the findings indicate that NLPHD represents a proliferation of germinal center cells.

Antibodies, Monoclonal↗
PubMed1986

Detection of Cowdria ruminantium antigen and antibody during the course of heartwater disease in sheep by means of an enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay was used to detect Cowdria ruminantium antibodies during the course of heartwater disease. IgM antibodies reached a maximum on the 4th day after infection and disappeared on the 7th day. IgG antibodies first appeared on the 8th day and continued to increase during the remainder of the observation period of 28 days. The presence of C. ruminantium in the blood fractions of diseased animals was demonstrated by an enzyme-linked immunosorbent assay. The earliest day of C. ruminantium antigen detection was in plasma and serum on the 4th day after inoculation. Of all the blood fractions investigated, the red blood cells showed the highest concentration, and this reached a maximum on the 12th day after infection.

Animals↗