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Biomedical subjects

A Frensdorff

Publications and source records attributed to A Frensdorff.

At least 19 recordsLinked to original sources
PubMed1992

Plasma tumor necrosis factor soluble receptors in chronic renal failure.

Two soluble tumor necrosis factor receptors (sTNFRs) were detected in the plasma of patients with different degrees of chronic renal failure (CRF) and of long-term hemodialysis (HD) patients. In uremic undialyzed patients, plasma levels of both sTNFRs increased progressively with declining renal function. A linear correlation was found between sTNFR plasma levels and plasma creatinine concentration. sTNFR levels in end-stage uremic patients shortly before commencement of first HD treatment were approximately tenfold higher than in normal subjects. Long-term HD patients showed a further increase in plasma sTNFRs. The origin of sTNFRs, as well as their physiological role remains to be elucidated.

Adult↗
PubMed1978

Suppressed murine mammary tumor virus (MuMTV) expression in RIII female mice treated neonatally with goat antiserum to MuMTV.

Passive immunization of newborn inbred RIII (R3) mice with the globulin fraction of goat antiserum to murine mammary tumor virus (MuMTV) successfully suppressed MuMTV expression in the milk of some of the treated mice throughout nine successive lactations. No mammary tumors developed in the MuMTV-suppressed mice during the first 9 months, whereas all untreated R3 female breeders expressed MuMTV in the milk of the third lactation, and all developed tumors before 9 months of age (mode and median: 189 days).

Animals↗
PubMed1976

Hyphal walls of isolated lichen fungi: autoradiographic localization of precursor incorporation and binding of fluorescein-conjugated lectins.

The hyphal walls of three mycobionts, isolated from the lichens Xanthoria parietina, Tornabenia intricata and Sarcogyne sp. were investigated by two techniques: microautoradiography of fungal colonies exposed to radioactive carbohydrate precursors: and binding, in vivo, of fluorescein conjugated lectins to hyphal walls of such colonies. N-[3H] acetylglucosamine was readily incorporated into tips, young hyphal walls and septa of the three mycobionts and the free-living fungus Trichoderma viride, but not into Phytophthora citrophthora, indicating that chitin is a major component of the mycobionts' hyphal walls. All three mycobionts, but neither of the free-living fungi, incorporated [3H] mannose and [3H] mannitol into their hyphal walls. Fluorescein-conjugated wheat germ agglutinin was bound to the hyphal walls of the three mycobionts and T. viride, but not to the walls of P. citrophthora; the binding pattern was similar to the grain pattern obtained in autoradiographs after short N-[3H]acetylglucosamine labelling. As wheat germ agglutinin binds specifically to chitin oligomers, the lectin binding tests further confirmed that chitin is a mycobiont hyphal wall component. Binding characteristics of several fluorescein-conjugated lectins to the three mycobionts indicated that this technique can yield useful information concerning the chemical composition of hyphal wall surfaces.

Acetylglucosamine↗
PubMed1976

Isolation of lymphocyte subpopulations from rabbit peripheral blood. Comparison of methods based on recovery of rosette-forming cells and on recovery of Ig-bearing cells from a digestible immunoadsorbent.

Two methods to obtain lymphocyte subpopulations, defined by specific surface receptors, from rabbit peripheral blood cells were compared as to cell recovery, yield and purity of the obtained fractions: a) the formation of rosettes between lymphocytes and SRBC or SRBC coated with an antigen--antibody--complement complex (D-SRBC), followed by isolation of the rosettes and recovery of the RFC, b) retention of surface-Ig bearing cells on an immunoadsorbent to which antibody to rabbit Ig was covalently attached via a digestible gelatin bridge, with subsequent recovery of the retained cells by the enzymatic digestion of the bridge. Purity of the isolated cell fractions was assessed in all cases by the percentage of cells staining with FITC-labeled goat anti-rabbit Ig. Using the rosette method, all of the RFC could be recovered from rosettes and a very pure, surface-Ig negative, sub-population of cells was obtained: however, the overall number of rosettes formed (SRBC and D-SRBC) was low (8-9% of the nucleated PBC). Very good recoveries and highly enriched cell populations were obtained with the digestible immunoadsorbent, provided certain precautions to minimize cell losses were taken. Thus, 47% of the input cells, representing 90% of the lymphocytes could be recovered; separated cell populations were 96% Ig-positive or, in another experiment, 96% Ig-negative.

Adsorption↗
PubMed1976

Effect of vinblastine on the early events in the humoral immune response of mice to SRBC.

The effect of vinblastine (VLB), a mitotic blocking agent, on the number of plaque-forming cells (PFC) and on the metabolic activities of spleen cells of mice reimmunized with SRBC was studied. When VLB (75 mug/mouse) and antigen were administered simultaneously, the number of pfc, on the 4th day after immunization, was reduced to 40% of control levels. However, when the same amount of VLB was administered to mice 24 h after immunization, it reduced the number of PFC to 10% of control levels. The possibility that VLB exerts a specific cytotoxic effect on preformed PFC either in vivo or in vitro was ruled out. A direct profound effect of VLB on antigen-stimulated cells was observed when VLB was injected 24 h after reimmunization, and the incorporation rates of radioactive precursors into macromolecules by spleen cells were measured at 4-hour intervals. VLB suppressed completely the antigen-induced peak of 3H-thymiding incorporation, while it had no effect on the incorporation rate of 3H-uridine and only a slight effect on the incorporation rate of 3H-amino-acids by the same cells. The results suggest that the decrease in number of PFC caused by injection of VLB 24 h after immunization is due to prevention by VLB, of precursor cells from going through a critical cell division, which takes place later than 24 h after immunization. Thus, at least one cell division is required for an immune response in vivo.

Animals↗
PubMed1976

Receptors for immune complexes on cells within a non-lymphoid murine tumor.

In this paper we present evidence that antibodies unrelated to the tumor cell can comprise part of the in vivo Ig surface coat of cells derived from the non-lymphoid murine tumor, TA3/St. This was shown by incubating TA3 cells originating from other OA or BSA preimmunized mice with radioiodinated 125I-OA and 131I BSA. Radioiodine-labeled 125I-OA specifically fixed to cells derived from TA3/St tumors originating from OA-preimmunized mice. On the other hand 131I-BSA was specifically fixed by cell populations from BSA-preimmunized mice. Incubation of these cells in vitro at 37 degrees C abolished the specific binding and antibody could subsequently be detected in the tissue culture medium. Radioiodine labeled purified soluble antibody-antigen complexes could also be bound to cells derived from freshly harvested TA3/St tumors but not to their in vitro propagated counterparts. Removal of phagocytic or adherent cells from these cell populations decreased the binding of the complexed antibody on freshly harvested TA3/St populations, but did not eliminate it. Inhibition of complexed antibody binding was obtained when TA3/St cells (an H-2a tumor) were pre-incubated with anti-H2a antiserum. Propagation of the tumor in an F1 hybrid (A X C57BL) in which host cells could be distinguished from tumor cells by using an anti H-2b antiserum showed that binding of the immune complex was mostly limited to host cells infiltrating into the tumor population.

Animals↗
PubMed1976

Hybridization kinetics of ribonucleic acid and deoxyribonucleic acid from antigen-stimulated mouse spleen cells.

In an attempt to explore the mechanism by which antigenic stimulation alters gene expression in lymphoid cells in vivo, three different hybridization techniques have been used to compare the complexity of the genome of lymphoid cells from normal and from immune BALB/c mice. RNA/DNA hybridization experiments at a DNA excess of 1000 demonstrated that normal RNA and immune RNA hybridized identically with DNA extracted from mouse spleen cells before and after immunization and with liver DNA. These findings indicate that DNA sequences complementary to immune RNA or to normal RNA are represented in a number of copies not significantly different in the genome of normal lymphoid cells and in that of immune lymphoid cells. Hybridizations of normal and of immune RNA with normal and immune pulse-labeled DNA, done at RNA excess, detected no differences between these two DNA. However, significant differences were observed in the percentage of DNA hybridized with normal and immune RNA; 3 to 4% of the DNA hybridized with normal RNA and 8 to 9% with immune RNA. This indicates that more DNA sequences are transcribed 48 hr after immunization than before immunization. The RNA exhaustion rates caused by normal and immune DNA were found to be identical, indicating that antigenic stimulation did not induce major changes in the number of DNA base sequences complementary to the RNA tested. However, when normal and immune pulse-labeled RNA were compared by exhaustion with DNA, the immune pulse-labeled RNA obtained 48 hr after immunization displayed a slower exhaustion rate than normal RNA or RNA extracted 72 hr after immunization. These results suggest the temporary synthesis, at a higher frequency, of certain RNA sepcies 48 hr after immunization, as compared to the RNA synthesis in normal, nonimmune cells, or that occurring 72 hr after immunization. Thus, the three experimental approaches used lead to the conclusion that antigenic stimulation does not induce major gene amplification; it does, however, change the transcription rate of certain RNA species.

Animals↗
PubMed1975

Reassociation kinetics of deoxyribonucleic acid in antigen-stimulated mouse-spleen cells.

In order to directly compare the complexity of the genome of lymphoid cells which have been antigenically stimulated, with that of non-immunized and non-lymphoid cells, DNA was pulse labeled and extracted from BALB/c mouse spleen cells at various time intervals after antigenic stimulation in vivo; the reassociation rates of these newly synthesized DNA preparations were compared with those of the total mouse spleen DNA, obtained from same sources and at the same times. DNA labeled for 60 min at 43, 53, or 72 h after antigenic restimulation, reassociated faster than the corresponding total DNA. On the other hand, the ressociation profile of DNA, labeled for 60 min during the first 24 after restimulation did not differ from that of the total DNA extracted at the same time. When labeled thymidine was available for incorporation at a constant concentration over a period of 24 h, reassociation patterns of labeled DNA were identical to those of the corresponding total DNA at all times after restimulation. Newly synthesized nuclear DNA exhibited reassociation profiles identical to those of the corresponding total nuclear DNA at all times tested. Also, no differences between the reassociation rates of nuclear and total cellular DNA were observed. It was concluded that antigenic stimualtion does not induce a major amplification of genes in the stimulated cells, and that the rapidly reassociating DNA species described represent extranuclear (cytoplasmic) DNA.

Animals↗
PubMed1975

'Gelbsilber' rabbits: a closed colony of high responders to the lactic dehydrogenase isoenzyme LDH-H4. Possible mechanisms controlling the response.

'Gelbsilber' (GS) rabbits which had been maintained for an unknown time as a closed colony, were found to respond uniformly well to the pig lactic dehydrogenase isoenzyme of the H4 type (P-LDH-H4), to which most New Zealand white (NZW) rabbits produced no detectable antibody. Two to three per cent of the splenic lymphoid cells of GS rabbits after secondary immunization were found to produce antibody to P-LDH-H4, while no such cells were detected in NZW rabbits. No differences were detected between the electrophoretic mobility of endogenous LDH of GS and NZE rabbits. The immunoglobulins of GS rabbits were heterogeneous with respect to immunoglobulin light and heavy chain allotypes. It was concluded that in GS rabbits the response to LDH-H4 is controlled by and Ir gene and that these animals might be useful in studying the genetic control of the immune response in rabbits.

Animals↗
PubMed1971

Selective simulation of allelic expression: effectf antibodies to allotypic markers on lymphoid cells.

Peripheral blood leukocytes from rabbits which were heterozygous (b(5)/b(9)) for markers on their immunoglobulin light chains were maintained in vitro for up to 24 hours in the presence or absence of antibody to b9. After culture they were transferred into lethally irradiated b(4)/b(4)hosts. Recipients of cells exposed to antibodies to allotype markers showed a striking increase in concentration of circulating b9 molecules and number of b9 plasma cells in their spleens compared pared to control animals receiving untreated cells from the same donor. There was no appreciable difyerence between the two groups of recipients with respect to their content of b5 molecules and immunocytes.

Alleles↗