Scientific Resources

Lymphoblasts from 93 children with acute lymphoblastic leukemia (ALL) were characterized by immunologic cell surface markers. These patients were treated on a single protocol,featuring adriamycin therapy during remission,and have been followed from 2 to 6.5 yr (median 4 yr). Three classes of patients were defined serologically: HTA+ Ia- CALLA-,Ia+ CALLA+ HTA-,and Ia+ CALLA- HTA-. Disease-free survival and sites of relapse were assessed within immunologic subsets. Similar to the findings of others,T-cell (HTA+ Ia-) patients fared poorly as compared to non-T-cell (Ia+ HTA-) patients (median disease-free survival was 12 and 47 mo. respectively; p = 0.0004). The majority of relapses in the HTA+ patients occurred at extramedullary sites. Late testicular relapse was rare among Ia+ patients. In addition,the common ALL antigen" (CALLA) may identify a relatively favorable subset within the Ia+ population. The prognostic value of the immunologic markers was compared with traditional clinical factors. There was much overlap between HTA+� View Publication

This report describes the establishment directly from normal preimplantation mouse embryos of a cell line that forms teratocarcinomas when injected into mice. The pluripotency of these embryonic stem cells was demonstrated conclusively by the observation that subclonal cultures,derived from isolated single cells,can differentiate into a wide variety of cell types. Such embryonic stem cells were isolated from inner cell masses of late blastocysts cultured in medium conditioned by an established teratocarcinoma stem cell line. This suggests that such conditioned medium might contain a growth factor that stimulates the proliferation or inhibits the differentiation of normal pluripotent embryonic cells,or both. This method of obtaining embryonic stem cells makes feasible the isolation of pluripotent cells lines from various types of noninbred embryo,including those carrying mutant genes. The availability of such cell lines should made possible new approaches to the study of early mammalian development. View Publication

Serotonin receptor affinity and photelectron spectral data were obtained on a number of substituted N,N-dimethyltryptamines. Evidence is presented that electron-donating substituents in the 5-position lead to enhanced behavioral disruption activity and serotonin receptor affinity as compared to unsubstituted N,N-dimethyltryptamine and analogues substituted in the 4- or 6-position. Some correlation was found between ionization potentials and behavioral activity,which may have implications concerning the mechanism of receptor binding. View Publication

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Sinefungin (A9145) and a related metabolite,A9145C,were found to be potent inhibitors of Newcastle disease virion and vaccinia virion mRNA(guanine-7-)-methyltransferase and vaccinia virion mRNA(nucleoside-2'-)-methyltransferase. Both Sinefungin and A9145C were competitive inhibitors of these S-adenosyl-L-methionine-dependent enzymes having inhibition constants substantially less than S-adenosyl-L-homocysteine. These compounds also inhibited plaque formation by vaccinia virus in mouse L-cells. View Publication

The electrophoretic pattern of the large microtubule-associated protein,MAP2,changes during rat brain development. Immunoblots of NaDodSO4 extracts obtained from the cerebral cortex,cerebellum,and thalamus at 10-15 days after birth reveal only a single electrophoretic species when probed with any of three MAP2 monoclonal antibodies. By contrast,adult MAP2 contains two immunoreactive species,MAP2a and MAP2b. The single band of MAP2 from immature brain electrophoretically comigrates with adult MAP2b. Between postnatal days 17 and 18,immature MAP2 simultaneously resolves into two species in both the cerebellum and cerebral cortex. Immunoblots of NaDodSO4 extracts from spinal cord demonstrate the adult complement of MAP2 by day 10,indicating that MAP2 does not change coordinately throughout the entire central nervous system. In vitro cAMP-dependent phosphorylation of immature MAP2 causes a band split reminiscent of that seen during brain development in vivo. The possibility that the developmentally regulated changes observed in MAP2 during brain maturation are due to timed phosphorylation events is discussed. View Publication

In HeLa cells which have been exposed to 5 mM sodium butyrate for 21 h,the level of histone acetylation is greatly increased as compared to control cells (Riggs,M.G.,Whittaker,R.G.,Neumann,J.R.,and Ingram,V.R. (1977) Nature 268,462-464). Our experiments indicate that the increase in the relative amounts of multiacetylated forms of histones H4 and H3 following butyrate treatment is the result of an inhibition of histone deacetylase activity. View Publication

A hybrid cell line resulting from the fusion of a Con A-activated normal mouse spleen cell and a transformed mouse T cell (EL-4BU) has been used to prepare and select rat monoclonal antibodies reactive with molecules expressed on the surface of proliferating,as opposed to resting,mouse T cells. In this report,the characterization of two such antigens identified in this way is described. One antigen is a membrane component common to mitogen-activated T and B cells,some bone marrow cells,and various transformed cell lines but is not detectable on either normal thymocytes or the majority of spleen cells by radioimmunoassay or FACS analysis. It has a m.w. of approximately 200,000 daltons under nonreducing conditions and 100,000 daltons under reducing conditions. Antibodies to this antigen precipitate cell-bound transferrin but do not react directly with transferrin itself. It would thus appear that the antigen is the transferrin receptor molecule. The second antigen is not detectable on normal thymocytes,spleen cells,bone marrow cells,or mitogen-stimulated spleen cells but is expressed at high levels on some transformed T cell lines. It,too,appears to be a dimer,with a m.w. of 95,000 daltons under nonreducing conditions,decreasing to 50,000 daltons under reducing conditions. Although the function of the 95,000-dalton antigen is not yet known,its lack of expression on adult T cell populations both before and after activation suggests either a short-lived role at a very early stage of T cell development and/or an association with T cell transformation. View Publication

Central stimulant actions of 10 methylxanthines in mice correlate with affinities for adenosine receptors labeled with N6-[3H]cyclohexyladenosine. Affinities of methylxanthines for adenosine receptors are consonant with central levels attained at behaviorally effective doses. The much higher concentrations of methylxanthines required to influence benzodiazepine receptor binding do not correlate with behavioral potency. N6-(L-Phenylisopropyl)adenosine (L-PIA),a metabolically stable analog of adenosine with high affinity for adenosine receptors,is an extremely potent behavioral depressant,reducing locomotor activity of mice at doses as little as 0.05 mumol/kg. The D isomer,which has much less affinity for adenosine receptors,is much less active as a central depressant. Theophylline stimulates locomotor activity and reverses depressant effects of L-PIA. Caffeine or 1,7-dimethylxanthine,when administered alone,elicits biphasic effects,with locomotor depression at lower doses and stimulation at higher doses. When administered with L-PIA,even low doses of caffeine produce marked stimulation. 3-Isobutyl-1-methylxanthine given alone elicits only behavioral depression. However,like theophylline and caffeine,isobutylmethylxanthine reverses the L-PIA-evoked depression,converting it into pronounced locomotor stimulation. The data strongly suggest that the behavioral stimulant effects of methylxanthines involve a blockade of central adenosine receptors. View Publication

Bay K8644 increased unidirectional Ca2+ influx and produced tension development in rabbit aorta. Both responses could be evoked in the tissue maximally stimulated with norepinephrine. When the arterial rings were maximally activated by high K+ depolarization,Bay K8644 was without effect. The tension evoked by high K+ and Bay K8644 was more sensitive to the dihydropyridine Ca2+ antagonist PY108-068 than norepinephrine induced tension. These results indicate that Bay K8644 activates only potential operated Ca2+ channels which are opened by high K+ depolarization. View Publication

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We cultured sensory neurons from chick embryos in media containing the alkaloid taxol at concentrations from 7 X 10(-9) to 3.5 X 10(-6) M. When plated at taxol concentrations above 7 X 10(-8) M for 24 h,neurons have short broad extensions that do not elongate on the culture substratum. When actively growing neurites are exposed to these levels of taxol,neurite growth stops immediately and does not recommence. The broad processes of neurons cultured 24 h with taxol contain densely packed arrays of microtubules that loop back at the ends of the process. Neurofilaments are segregated from microtubules into bundles and tangled masses in these taxol-treated neurons. At the ends of neurites treated for 5 min with taxol,microtubules also turn and loop back abnormally toward the perikaryon. In the presence of 7 X 10(-9) M taxol neurites do grow,although they are broader and less branched than normally. The neurites of these cells appear to have normal structure except for a large number of microtubules. Taxol probably stimulates microtubule polymerization in these cultured neurons. At high levels of the drug,this action inhibits neurite initiation and outgrowth by removing free tubulin from the cytoplasm and destroying the normal control of microtubule assembly in growing neurites. The rapid inhibition suggests that microtubule assembly may occur at neurite tips. At lower concentrations,taxol may slightly enhance the mechanisms of microtubule assembly in neurons,and this alteration of normal processes changes the morphogenetic properties of the growing neurites. View Publication