Search PubMed⌕ Search

Biomedical subjects

A Hatzfeld

Publications and source records attributed to A Hatzfeld.

At least 55 records · Page 3Linked to original sources
PubMed1985

A method to measure receptor binding of ligands with low affinity. Application to plasma proteins binding assay with hemopoietic cells.

A gradient has been developed for separating free ligand from ligand bound to cells growing in suspension. This method can be used with all kinds of ligand but it is particularly useful for those ligands having the tiresome tendency to adhere to the cells non-specifically or to polymerize by themselves. This is the case of fibronectin, fibrinogen, immunoglobulins and many other plasma proteins. The gradient consists of two layers: an upper aqueous phase and a lower hydrophobic organic phase. The aqueous phase, a sucrose buffer, allows the cells to become well dispersed before they enter the hydrophobic phase which excludes the free ligand efficiently. This reduces non-specific binding and allows the accurate measurement of specific binding which could not be obtained with a gradient made of a single phase. Depending upon the size and the density of the cells, and the nature of the ligand, the assay method can be modified by changing the density or the nature of the hydrophilic and hydrophobic phases.

Cell Count↗
PubMed1982

Fibrinogen and its fragment D stimulate proliferation of human hemopoietic cells in vitro.

Purified fibrinogen at concentrations of 3-30 nM has been found to stimulate continuous growth of human lymphoid and myeloid cell lines under serum-free conditions. A strong proliferative response resulted from the synergism elicited by the addition of fibrinogen to transferrin-supplemented medium. This effect was observed with the pre-B-cell line Raji, the T lymphoma-derived JM, and the monocytic cell line U 937, either at high or low cell densities. With the promyelocytic cell line HL 60, fibrinogen did not shorten the doubling time of cultures seeded at high cell densities (2 x 10(5) cells per ml). However, at cell densities lower by 2 orders of magnitude and in the same medium, it promoted growth with a doubling time similar to that obtained at high cell concentrations. Fibrinogen also was found to increase the plating efficiency and colony size when human bone marrow cells were cultured in semisolid medium containing serum. In long-term bone marrow liquid cultures without fibrinogen, colony-forming cells were no longer detected after 6 weeks. In those cultured with fibrinogen, approximately equal to 50 granulocyte-macrophage colonies per 10(5) cells were obtained after 6 weeks, and 10, after 12 weeks. Purified fibrinogen fragment D possessed a stimulating activity similar to that of the intact fibrinogen molecule. This fragment cannot form fibrin, thus eliminating fibrin as a source of the mitogenic effect.

Cell Division↗
PubMed1982

Ontogeny of Nk-1+ natural killer cells. I. Promotion of Nk-1+ cells in fetal, baby, and old mice.

Using anti-Nk-1.1 serum, the alloantiserum specific for murine natural killer (NK) cells, we followed the ontogenetic development of Nk-1+ cells in fetal thymus, liver, and spleen. A transient population of Nk-1+ cells in fetal thymus was observed on day 14 but not on day 16 of gestation. On day 16 of gestation, Nk-1+ cells were detected only in liver and spleen. The proportion of Nk-1+ cells in spleen remained high (20 to 30%) at birth and persisted until 2 to 3 wk old. The Nk-1+ cells in "baby" (1 to 2 wk old) spleen bound to YAC cells but failed to lyse them in 51Cr-release assay. Upon induction with interferon (IF), the proportion of Nk-1+ cells increased, but the lytic activity remained low, suggesting that the "baby" NK-1+ cells are immature in lytic function. In old mice (12 to 14 mo), Nk-1+ cells were also detectable, even though NK activities were lower compared with those of the young adult (6 to 8 wk old) mice. The Nk-1+ cells of old mice were readily induced by IF to exhibit activities, and the induced NK cells were Nk-1+. We have thus established Nk-1.1 antigen as an early hemopoietic differentiation antigen. Splenic Nk-1- cells could be induce by IF to become NK-1+ cells, which could be inactive or active in NK assays, dependent on the age of the mice.

Aging↗
PubMed1981

Relation of gp70 to spontaneous cytolytic activity of mouse spleen cells.

In comparing spleen cells of inbred and congenic mice for spontaneous capacity to lyse cells of the BALB/c leukemia RLmale1 in vitro, we found that the activity of 129 spleen cells was more than double that of 129-Gix- spleen cells. The only known difference between these two strains is that 129-Gix- mice express no known demonstrable gp70 or p30, whereas 129 mice express both these MuLV-related components as mendelian traits not associated with the production of virions. We infer that MuLV-related components at the cell surface are concerned in effector-target interactions leading to cytolysis under the conditions described. Although the congenic strains B6 (Gix-) and B6-Gix+ differ likewise in expression of the type-variant Gix-gp70, both strains express a second type-variant of gp70. The lytic activity of spleen cells of these two strains for RLmale1 cells was equally high, suggesting that involvement in lytic effector-target interactions is common to gp70 molecules in general. When used as targets rather than as effectors 129 spleen cells were more sensitive to lysis than 129-Gix- spleen cells. Pre-exposure to gp70, purified from R-MuLV, rendered splenic effector cells less lytic. Pre-exposure to gp70 also rendered RLmale1 target cells less sensitive to lysis. One explanation of these findings is that both target cells and effector cells express gp70 and also receptors for gp70 and that this is the basis of mutual cellular recognition leading to lysis in the circumstances described.

AKR murine leukemia virus↗
PubMed1980

Ly-m11: the H-3 region of mouse chromosome 2 controls a new surface alloantigen.

Spleen cells from an SJL mouse immunized with B10.S spleen cells were fused with the nonsecretor myeloma line NS.1. One established hybrid cell line continuously secreted antibody that recognized a new antigenic specificity, tentatively called "Ly-m11." This newly found antigen is detectable on nearly 100 percent of spleen and lymph-node cells, 70 percent of bone-marrow cells, and 20 percent of thymus cells by direct cytotoxicity assays, and on the cells derived from kidney and liver. Strains that are Ly-m11 (+) include C57BL/6, C57BL/10J, B10.S, C57BR/cdJ, C57L/J, and C57BL/KsJ. Other mouse strains so far tested are Ly-m11 (-). The strain distribution pattern distinguished Ly-m11 from any known murine lymphocyte alloantigens, but it follows the H-3 alpha haplotype which is defined by skin transplantation. Linkage tests of nine congenic strains of H-3 and/or H-13/alpha loci and five recombinant inbred lines including CXB, BXH, AKXL, SWXL, and BXD revealed no recombinations between H-3 and Ly-m11 loci on chromosome 2. This newly discovered Ly-m11 alloantigen could itself constitute a minor histocompatibility antigen detectable by serological means.

Animals↗
PubMed1978

Location of adult and fetal aldolases A, B, and C by immunoperoxidase technique in LF fast-growing rat hepatomas.

The resurgence of aldolase isozymes in cancerous tissues is a well-known but poorly understood phenomenon. This resurgence poses the problem of whether or not adult and fetal aldolase isozymes are produced by the same cells. For clarification of this question, the immunoperoxidase technique was used to locate aldolases A, B, and C in one type of fast-growing hepatoma, the LF hepatoma and, by comparison, in normal adult liver. Under optical microscopy, aldolases A and C were located in the cytoplasm of almost all of the cancerous cells. An isozyme antigenically identical with aldolase B was also demonstrated to be present in almost all of the cells, but the reaction indicating the presence of this isozyme was weaker. In normal adult liver, only aldolases A and B were demonstrated to be present in almost all the hepatocytes. Under electron microscopy in LF hepatoma, the three isozymes were found to be present mainly in the cytoplasm. These facts suggest that the three types of aldolase are very probably present in the same cells at the same time, and they provide indirect arguments leading us to think that the resurgence of fetal aldolase isozymes in cancer is not the consequence of cellular selection but is due to a disturbance at the gene control level.

Animals↗
PubMed1977

Isoelectrofocusing of aldolase B from normal human livers and from livers with hereditary fructose intolerance.

By isoelectrofocusing in thin-layer acrylamide-ampholine gel, normal human aldolase B has been resolved into 5 bands. Moreover we were able to specifically stain (after isoelectrofocusing) the mutated aldolase B in livers with hereditary fructose intolerance, and to show that only the 3 most anodic bands are seen. Some different hypotheses are discussed to account for the microheterogeneity of the normal aldolase B, and for the different isoelectrofocusing pattern found in livers with hereditary fructose intolerance.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1977

Purification of aldolase C from rat brain and hepatoma.

An isolation procedure for rat brain aldolase C has been developed which also permits the isolation of aldolase C from experimental hepatomas. Certain enzymatic properties (specific activity and Michaelis constant towards the two specific substrates: fructose 1,6-biphosphate and fructose 1-phosphate) and physico-chemical properties (molecular weight, N-terminal amino-acid) of the two enzymes have been studied and compared. Moreover, an amino-acid analysis has been carried out for rat brain aldolase C. Within experimental errors, the two enzymes appear to be identical.

Amino Acids↗
PubMed1975

Resurgence of two fetal aldolases in rat duodenal adenocarcinomas.

We have shown, by kinetic, electrophoretical and immunological methods, the resurgence of two intestine fetal aldolases (A and C) in well-differentiated rat duodenal adenocarcinomas. Our findings demonstrate that the resurgence of fetal isozymes in cancer is a general phenomenon, occurring in intestine, as in liver and other tissues.

Adenocarcinoma↗