Search PubMed⌕ Search

Biomedical subjects

L Sachs

Publications and source records attributed to L Sachs.

At least 253 records · Page 14Linked to original sources
PubMed1976

Control of lysozyme induction in the differentiation of myeloid leukemic cells.

A system has been developed with clones of mouse myeloid leukemic cells in culture to study the induction of synthesis and secretion of lysozyme in relation to other steps in myeloid cell differentiation. Lysozyme was initially absent in all the clones studied. The different clones can be divided into three types according to their ability to be induced to undergo normal cell differentiation by the protein inducer MGI (macrophage and granulocyte inducer). One type of clone that can be induced by MGI to form Fc and C3 receptors and differentiate to mature macrophages and granulocytes (MGI+D+) was also induced by MGI to synthesize and secrete lysozyme. Lysozyme was induced after Fc and C3 receptors, and labeling with 35S-methionine has shown that the induced lysozyme was newly synthesized. MGI+D+ clones were also induced to synthesize and secrete lysozyme by dexamethasone, prednisolone, cytosine arabinoside, or thymidine and in one of four clones by dimethylsulfoxide but not by sodium butyrate. Inhibition of cell multiplication by itself was not sufficient to induce lysozyme synthesis. A second type of clone which can be induced by MGI to form Fc and C3 receptors but not mature cells (MGI+D-) was more weakly inducible by MGI for lysozyme and was not inducible by any of the other compounds. A third type of clone (MGI-D) MGI for receptors or mature cells. One of four MGI-D- clones was induced to synthesize but not secrete lysozyme by dexamethasone together with sodium butyrate, but there was no lysozyme induction by MGI or any of the other compounds separately. The different clones maintained their different properties for at least 6 months in culture. The results indicate that clones with different hereditary blocks in the ability to be induced to differentiate by specific compounds can be used to dissect the process of myeloid cell differentiation, that the sequence of differentiation is induction of Fc and C3 receptors leads to lysozyme leads to mature cells, and that there are separate controls for these developmental steps.

Bromodeoxyuridine↗
PubMed1976

Mutability of different genetic loci in mammalian cells by metabolically activated carcinogenic polycyclic hydrocarbons.

The relationship between carcinogenesis and mutagenesis in mammalian cells has been determined with 10 polycyclic hydrocarbons with different degrees of carcinogenicity. Mutagenesis was determined in Chinese hamster cells with genetic markers that affect the surface membrane, nucleic-acid synthesis, and protein synthesis. The mutations were characterized by resistance to ouabain, 8-azaguanine, and temperature. Mutagenesis by the carcinogens required metabolic activation and this was provided by the presence of lethally irradiated metabolizing cells. The degree of carcinogenicity was related to the degree of mutagenicity for all three genetic markers. The most potent carcinogen, 7,12-dimethylbenz[a]anthracene, gave the highest mutagenicity and mutagenicity was obtained with 0.01 mug/ml. Treatment of the cells with aminophylline, which increases polycyclic hydrocarbon metabolism, increased mutagenesis by the carcinogens. It is suggested that such an experimental system with these and other mammalian cells should be useful as a sensitive assay for hazardous environmental chemicals.

Aminophylline↗
PubMed1976

Regulation of the induction of colonies in vitro by normal human lymphocytes.

Lymphocytes isolated from normal human peripheral blood can be induced to form colonies in vitro by incubation with the appropriate inducer. Phytohemagglutinin can induce colonies with T (thymus-derived) lymphocytes. Optimun colony formation with about two colonies per 10(2) peripheral blood lymphocytes was obtained by adding, in addition to phytohemagglutinin, autologous plasma, autoologous red blood cells, and fresh L-glutamine or L-cystine. In the absence of these fresh amino acids, no colonies were formed at seeding levels below 10(5) cells per 35 mm petri dish. The addition of either of these amino acids gave a 10-fold decrease in the minimum number of cells that had to be seeded for colony formation. Lipopolysaccharide did not induce the formation of colonies, but enhanced the formation of T cell colonies by phytohemagglutinin. The mixing of lymphocytes from persons with and deficient in glucose-6-phosphate-dehydrogenase (EC 1-1-1-49) has shown that phytohemagglutinin-induced colonies can be derived from single cells and are, therefore, clones. No colonies were formed by lethally irradiated cells. Incubation with pokeweed mitogen also induced the formation of colonies. With autologous plasma and autologous red blood cells, pokeweek mitogen induced about one colony per 5 X 10(3) cells seeded and no colonies at seeding levels below 10(5) cells per petri dish. The minimum number of cells needed for colony formation by pokeweed mitogen was not decreased by fresh L-glutamine or L-cystine. The results indicate that normal human lymphocytes can be cloned in vitro and that induction of these lymphocyte colonies can be regulated by lectins and other specific factors.

Blood↗
PubMed1976

Identification of mutagenic metabolites of benzo(a)pyrene in mammalian cells.

The mutagenicity of benzo[a]pyrene and 15 of its derivatives, which included phenols, the benzo[a]yrene-4,5-epoxide (the K-region epoxide), dihydrodiols, two isomeric 7,8-diol-9,10-epoxides, a 6-methyl derivative, and a 6-hydroxymethyl derivative, were tested with Chinese hamster V79 cells in order to identify the mutagenic metabolites of benzo[a]pyrene. Mutations were characterized by resistance to ouabain or 8-azaguanine. Since V79 cells do not metabolize polycyclic hydrocarbons, mutagenesis was tested both in the presence and absence of benzo[a]pyrene-metabolizing normal golden hamster cells. All the tested phenols, 4,5-diols, trans-9,10-diol, 6-methyl, and 6-hydroxymethyl derivatives of benzo[a]pyrene showed little or no mutagenicity for both genetic markers. The (+/-)7alpha,8beta-dihydroxy-9alpha,10alpha-epoxy-7,8;9,10-tetrahydrobenzo[a]pyrene and K-region 4,5-epoxide exhibited similar and moderate mutagenicity in the absence of benzo[a]pyrene-metabolizing cells, but the (+/-)7alpha,8beta-dihydroxy-9beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo[a]-pyrene showed a 2000- and 270-fold higher mutation frequency for ouabain and 8-azaguanine resistance, respectively, than did the K-region 4,5-epoxide. The trans-7,8-diol which was not mutagenic in the absence of benzo[a]pyrene-metabolizing cells was more mutagenic than benzo[a]pyrene after metabolism and mutagenesis by trans-7,8-diol in these cells was inhibited by 7,8-benzoflavone, an inhibitor of mixed-function oxidases. Metabolically formed trans-7,8-diol was isolated and incubated with rat liver microsomes in the presence of co-factors. High-pressure liquid chromatography analysis indicated that the major metabolite of trans-7,8-diol is 7alpha,8beta-dihydroxy-9beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene. The results indicate that the latter compound is metabolically formed and the major mutagenic intermediate of benzo[a]yrene metabolism.

Benzopyrenes↗
PubMed1976

Complete preimplantation development in culture of parthenogenetic mouse embryos.

The present experiments were undertaken to determine whether, in parthenogenesis, heterozygous embryos develop better than homozygous embryos. Such experiments may provide an approach to elucidating whether fertilized embryos develop better than parthenogenetic ones because of heterozygosity, or if the sperm provides another contribution necessary for complete embryonic development. The parthenogenetic embryos studied included uniform haploids after extrusion of the second polar body, mosaic haploids in which each blastomere contained a genetically different haploid nucleus, and heterozygous diploid mouse embryos. Eggs were activated and cultured in a chemically defined medium. About three times as many mosaic haploid or heterozygous diploid eggs developed beyond the 4-cell stage after 98-100 h and to the blastocyst stage after 120 h in culture, than uniform haploid eggs. This indicates that the development of parthenogenetic embryos is probably under genetic control and that there was a better development of the heterozygous embryos. Mosaic haploid embryos showed the same high frequency of development as heterozygous diploids. The results therefore indicate that heterozygosity provided a developmental advantage even when distributed between two genetically different clones of cells in the same embryo.

Animals↗
PubMed1976

Control of Fc and C3 receptors on myeloid leukemic cells.

An experimental system has been developed to study in cloned lines of cells the control of Fc and C3 receptors by different compounds. The cells used were clones of mouse myeloid leukemic cells and the compounds used were the protein MGI2 (macrophage and granulocyte inducer) in serum from mice injected with bacterial endotoxin and the steroid inducer (SI) dexamethasone. Eight clones were isolated which could be divided into three groups. One group (MGI+SI+) was induced to form EA and EAC rosettes by MGI and only EAC rosettes by SI, the second group (MGI-SI+) was not inducible by MGI but was induced by SI to form EA or EA and EAC rosettes, and the third group (MGI-SI-) was not inducible for EA or EAC by MGI or SI. There were two types of MGI+SI+ clones, one type (D+) could be induced by MGI to differentiate to mature macrophages and granulocytes, and the other type (D-) could not be induced to differentiate to mature cells. The MGI-SI+ and MGI-SI- clones were all D-. The results indicate that there are different cellular sites for MGI and SI and that induction of EA and EAC rosettes did not seem to be mediated by cyclic AMP. Experiments with specifically bound 3H-BSA-anti-BSA complexes have indicated that there was an increase in the amount of 3H-BSA-anti-BSA bound per rosette-forming cell following induction by MGI or SI, and there were differences in the amount of 3H-BSA-anti-BSA bound per rosette-forming cell in different clones. These clones also showed differences in the shape of the curve for the number of EA rosette-forming cells obtained with erythrocytes coated with decreasing concentrations of antibody. The results suggest that such curves and those obtained with EAC rosettes can be used to determine the relative abundance of EA and EAC receptors on rosette-forming cells. EA rosettes on the myeloid leukemic cells, like those on normal macrophages and granulocytes, were specifically inhibited by IgG2a and by the Fc but not the Fab fragment of IgG. The EAC rosettes were inhibited by destroying the C3 component of complement. The different clones maintained their specific properties for at least 6 months in culture. The present system should, therefore, also be useful for studies on the genetic control of the regulation of Fc and C3 receptors.

Animals↗
PubMed1975

Temperature sensitivity of cyclic-adenosine-3':5'-monophosphate-binding proteins, activity of protein kinases and the regulation of cell growth.

A clone of neuroblastoma cells has been selected for its ability to survive and multiply at 40 degrees C. This temperature-resistant clone, like clones of neuroblastoma cells selected for resistance to dibutyryladenosine 3':5'-monophosphate (Bt2-Ado-3':5'-P) showed an increased tumorogenicity in animals and an increased saturation density at 37 degrees C. The Ado-3':5'-P-binding proteins and Ado-3':5'-P-dependent protein kinases from the temperature-resistant and non-resistant cells have been partially purified by chromatography on a DEAE-cellulose column. The Ado-3':5'-P-binding proteins from temperature-resistant cells were more sensitive to temperature than the binding proteins from non-resistant cells. After incubation of binding proteins from resistant cells at 37 degrees C, the specific activity of Ado-3':5'-P-binding to proteins was decreased about 50% and the apparent association constant (Ka) for Ado-3':5-p-binding was decreased from 7.4 X 10(7)M-1 to 4.4 x 10(7)M-1. There was no such decrease with binding proteins from non-resistant cells. A decrease in the activity of binding proteins from the temperature-resistant cells, but not of those from non-resistant cells, was also found when the proteins were stored at 2 degrees C. Treatment with 2-mercaptoethanol made binding proteins from the resistant cells less temperature-sensitive. In the absence of added Ado-3:5-P the protein kinase activity from the temperature-resistant cells was about 50% of the activity from non-resistant cells. Kinase activity was increased by addition of Ado-3:5-P and there was a greater increase with kinases from resistant cells. The maximum protein kinase activity was found in the presence of 10muM Ado-3':5'-P for the temperature-resistant cells and 0.1 muM Ado-3':5'-P for the non-resistant cells. The results indicate that the temperature sensitivity of Ado-3':5'-P-binding proteins, and the activity of protein kinase from cells selected for resistance to high temperature, are similar to those of cells selected for resistance to Bt2-Ado-3':5'-P. It is suggested that the temperature sensitivity of Ado-3':5'-P-binding proteins and the activity of Ado-3':5'-P-dependent protein kinases are involved in the regulation of malignancy and of cell growth at different temperatures.

Binding Sites↗
PubMed1975

Mutation induction in Chinese hamster V79 cells by two vinyl chloride metabolites, chloroethylene oxide and 2-chloroacetaldehyde.

Chloroethylene oxide and 2-chloroacetaldehyde, two possibly carcinogenic metabolities of vinyl chloride in mammals, caused a dose-dependent induction of 8-azaguanine- and ouabain-resistant mutants in Chinese hamster V79 cells in vitro. Up to one-hundred-fold higher concentrations of 2-chloroethanol or monochloroacetic acid, a urinary vinyl chloride metabolite in rats and man, were inactive.

Acetaldehyde↗
PubMed1975

Regulation of aryl hydrocarbon (benzo-(A)-pyrene) hydroxylase activity in mammalian cells. Induction of hydroxylase activity by N6,O2'-dibutyryl8 adenosine 3':5'-monophosphate and aminophylline.

Treatment of hamster BHK cells with N6,O2'-dibutyryl adenosine 3':5'-monophosphate (Bt2cAMP), aminophylline, theophylline, or papaverine increased the level of aryl hydrocarbon (benzo(a)pyrene) hydrolxylase activity. The highese increase, 100-fold, was obtained with Bt2cAMP plus aminophylline or theophylline. N2,O2-Dibutyryl guanosine 3':5'-monophosphate gave a lower induction than Bt2cAMP. The level of hydroxylase activity started to decrease 6 hours after treatment with the inducer and was reduced to almost the uninduced level after 24 hours. Repeated addition of Bt2cAMP and aminophylline did not prevent this decrease. The hydroxylase can also be induced by treating cells with benz(a)anthracene, and the level of this induced activity was maintained for 24 hours. Aminophylline gave a 2- to 8-fold stimulation of the induction by benz(a)anthracene. The enzyme activity induced by Bt2cAMP, aminophylline, and benz(a)anthracene converted benzo(a)pyrene to similar alkali-extractable metabolities with a fluorescence spectra similar to that of 3-hydroxybenzo(a)pyrene. These induced enzyme activities also showed a similar heat stability. Induction by Bt2cAMP and aminophylline, like induction by benz(a)anthracene, required continued protein synthesis and only an initial period of RNA synthesis. Compared to the benz(a)anthracene-induced hydroxylase with a Km of 4.3 muM, the hydroxylase induced by Bt2cAMP and aminophylline showed a Km of 0.14 muM, and was 100-fold more sensitive to inhibition by 7,8-benzoflavone. Increasing the serum concentration in the culture medium stimulated the induction by aminophylline but did not stimulate induction by benz(a)anthracene. The results indicate that aryl hydrocaarbon (benzo(a)pyrene) hydroxylase can be induced by compounds that increase the level of adenosine 3':5'-monophosphate and that this induction and induced enzyme activity differs from that caused by benz(a)anthracene.

Aminophylline↗
PubMed1975

Induction of polyadenylate polymerase and differentiation in neuroblastoma cells.

Treatment of neuroblastoma cells with dibutyryl-adenosine 3':5'-monophosphate or adenine induced axon formation and a three-fold increase in the polyadenylate, poly(A), content of the polysomal mRNA. The extracted poly(A) contained 90% adenylic acid and showed a mobility of 6--7 S in dodecylsulfate-polyacrylamide gel electrophoresis. Treatment with dibutyryl-adenosine 3':5'-monophosphate or adenine, also induced a 4--6 fold increase in a nuclear enzymic activity that incorporated [3H]ATP to an acid-insoluble polymer in a cell-free system. This polymer, like poly(A) extracted from the polysomal mRNA, was bound at high salt concentration to nitrocellulose filters. [3H]ATP incorporation was Mg2+-dependent, sensitive to ribonuclease and EDTA and resistant to deoxyribonuclease and actinomycin D. There was no incorporation of [3H]UTP or [3H]dTTP and addition of TUP, CTP and GTP did not increase the incorporation of [3H]ATP. 5-Bromodeoxyuridine induced axon formation of neuroblastoma cells and poly(A) polymerase activity, without increasing the poly(A) content in the polysomal mRNA. The results indicate that induction of axon formation of neuroblastoma cells is associated with an increase in the activity of poly(A) polymerase. It is suggested that the induction of this enzyme may be generally involved in cell differentiation.

Adenine↗
PubMed1975

Induction of specific changes in the surface membrane of myeloid leukemic cells by steroid hormones.

Normal mature macrophages and granulocytes have surface membrane receptors for specific immunoglobulin and immunoglobulin complement, which can be detected by rosette formation with erythrocytes coated with antibody (EA) or with antibody and complement (EAC). There are three types of myeloid leukemia cells, IR-+D-+, IR-+D-minus and IR-minus D-minus. IR-+D-+ cells were induced to form receptors for EAC but not- for EA by the steroid hormones prednisolone, dexamethasone and estradiol. Induction required protein synthesis and was not inhibited by cordycepin or vinblastine. Optimum induction required the continued presence of the hormones. IR-+D-+ cells were also induced by these hormones to migrate in agar, attach to the surface of a Petri dish and form macrophages. IR-+D-minus cells showed a lower inducibility by these hormones and no formation of macrophages. There was no induction of any of these changes with IR-minusD-minus cells. The steroid hormones progesterone, testosterone and cortisone did not induce these changes in any of the leukemic cells and inhibited induction by prednisolone, dexamethasone and estradiol. The results indicate that specific surface membrane changes in myeloid leukemic cells can be induced by certain steroid hormones.

Animals↗