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Biomedical subjects

R Glaser

Publications and source records attributed to R Glaser.

At least 181 records · Page 10Linked to original sources
PubMed1983

Identification of a region of the Epstein-Barr virus (B95-8) genome required for transformation.

In a previous study the identification of a region(s) of the Epstein-Barr virus (EBV) genome, which is associated with transformation, was attempted by marker rescue. A transforming EBV was rescued from D98/HR-1 hybrid cells, which contain the non-transforming HR-1 EBV genome, after transfection with specific BamHI and Charon 4A fragments (J. Stoerker and R. Glaser, Proc. Nat. Acad. Sci. USA 80, 1726-1729, 1983). In this study, characterization of the EBV DNA in four human lymphoblastoid cell lines (LCL) transformed with rescued virus was performed. It was found that recombination between the transfected fragments, BamHI H,F,X and the Charon 4A fragment (EB-26-36) which is equivalent to the BamHI H,F,X region, and the endogenous HR-1 EBV genome in the D98/HR-1 cells took place. This recombination resulted in the formation of transforming EBV. The EBV DNA in the four LCLs are similar to each other and to HR-1 EBV DNA. However, the EBV DNA in all four LCLs also contain the U2 region plus additional sequences of B95-8 DNA. The U2 region is deleted in HR-1 EBV DNA which is associated with HR-1 cells and the D98/HR-1 hybrid cells. Thus, transforming activity of the HR-1-like viruses rescued from D98/HR-1 cells was concomitant with the recombination of the 0.26-0.36 region of the EBV genome, suggesting that this region is necessary for at least the initiation of transformation.

Cell Line↗
PubMed1983

Bis(bioreductive) alkylating agents: synthesis and biological activity in a nude mouse human carcinoma model.

Chemical investigations leading to the construction of bis(bioreductive) alkylating agents having both conformationally restricted and mobile spacer regions are described. Two targets having the conformationally mobile ethylene spacer group, namely, 2,2'-ethylenebis[6-(hydroxymethyl)-p-benzoquinone] diacetate (3b) and 2,2'-ethylenebis[6-(bromomethyl)-p-benzoquinone] (3c), were studied in vivo and in vitro using an established epithelial/Burkitt lymphoma hybrid cell line (D98/HR1) previously shown to induce carcinomas in nude mice. Inactivity of both test compounds in vitro, the relative resistance of these cells to test drugs in vitro, and the selective antitumor properties of the bis(bromomethyl) analogue in vivo lead to the proposal that this compound undergoes bioreduction to an alkylating species in the hypoxic core of the tumor, thereby exerting its action.

Animals↗
PubMed1983

Rescue of transforming Epstein-Barr virus (EBV) from EBV-genome-positive epithelial hybrid cells transfected with subgenomic fragments of EBV DNA.

Transfection experiments using subgenomic fragments of the B95-8 strain of Epstein-Barr virus (EBV) DNA and EBV genome (HR-1)-positive epithelial/Burkitt hybrid cells (D98/HR-1) were carried out to determine whether an interaction between the transfecting virus fragment(s) and the endogenous HR-1 EBV genome could take place. Expression of EBV-specific antigens, including early antigen and virus capsid antigen, was examined in transfected cells by immunofluorescence. Attempts were also made to recover biologically active EBV from the D98/HR-1 cells after transfection with cloned fragments of B95-8 DNA. We found that D98/HR-1 cells transfected with the BamHI H or H, F, and X fragments were positive for early antigen 3 days after transfection. Spent media from transfected D98/HR-1 cells maintained for 20-30 days in culture were pooled, filtered, concentrated, and used as a potential source of virus to inoculate human umbilical cord blood lymphocytes. No evidence of transformation was observed with such preparations. However, if spent medium from D98/HR-1 cell cultures was first treated with iododeoxyuridine (to induce EBV DNA synthesis and replicative cycle) and then transfected with the BamHI H, F, and X fragments of B95-8 DNA and used to infect cord blood lymphocytes, transformation was obtained. A lymphoblastoid cell line derived in this manner, designated HI-HFX, is an EBV nuclear antigen-positive nonproducer cell line. Similar results were obtained with preparations from iododeoxyuridine-treated D98/HR-1 cells transfected with the EB 26-36 fragment of B95-8 DNA cloned in a Charon 4A vector. The EB 26-36 fragment contains the BamHI H, F, and X regions.

Cell Transformation, Viral↗
PubMed1982

Antibody responses to Epstein-Barr virus-specific DNase in relation to the prognosis of juvenile patients with nasopharyngeal carcinoma.

We have examined serial sera from 17 juvenile patients with nasopharyngeal carcinoma (NPC) for their capacity to neutralize the activity of Epstein-Barr virus (EBV)-specific DNase. The results revealed that NPC patients who became long-term survivors (LTS) without evidence of the disease either never possessed significant levels of antibodies to the enzyme or showed a gradual decline in the number of EBV DNase units neutralized from an elevated level at diagnosis to an insignificant figure several years later. All the 10 LTS neutralized less than 4, and some neutralized less than 2 units of the enzyme 3 or more years after the initial diagnosis. In contrast, serial sera from juvenile patients who died of NPC neutralized over 10 and as many as 25 units of EBV DNase either persistently until death occurred or with transient declines during unmaintained remissions. Rises and declines in the neutralizing activity were, with few exceptions, accompanied by corresponding changes in the titers of IgA and IgG antibodies to EB viral capsid antigen and to the diffuse component of the early antigens. Although the number of juvenile NPC cases available for study was small, the observations suggest that the EBV DNase neutralization test may serve to provide information on the prognosis of the patients.

Adolescent↗
PubMed1982

The interaction of non-transforming Epstein-Barr virus (EBV) with cell-associated EBV DNA in superinfected lymphoblastoid cell lines.

Two human lymphoblastoid cell lines were established by the transformation of human cord-blood lymphocytes with transforming Epstein-Barr virus (EBV). One cell line (HLB-R1) was established with EBV obtained after the superinfection of Raji cells with HR-1 EBV and the other (HLB-Bl) was established from B95-8 EBV-infected human cord-blood lymphocytes. Both the HLB-R1 and HLB-B1 lines were susceptible to superinfection with HR-1 EBV. We found that EBV DNA was replicated in the superinfected cell lines and that transforming EBV was produced in both the HLB-B1 and HLB-R1 cells. The average titer of transforming EBV obtained in the HR-1 EBV superinfected HLB-B1 and HLB-R1 cell lines was 10(4) transforming units (TU)/ml, whereas the average titers of transforming EBV obtained by the superinfection of Raji cells was 10(1) TU/ml. Epstein-Barr virus capable of inducing early antigen (EA) in superinfected Raji cells (lytic virus) was not detected in any transforming virus preparation. Restriction enzyme digestion patterns of virus DNA isolated from HR-1 and B95-8 cells, as well as from superinfected cells, were compared. The EBV DNA that was replicated in the superinfected HLB-R1 and HLB-B1 cell lines showed a more complex pattern. Our data suggest that recombination between input HR-1 EBV DNA and latent cell-associated EBV DNA occurs. Presumably this recombination results in a change in the biological properties of the newly synthesized virus.

Burkitt Lymphoma↗
PubMed1982

Echinocyte formation induced by potential changes of human red blood cells.

In isotonic 30 mM NaCl-saccharose solution, human red blood cells with intact membrane and normal inside ionic content (C-state) indicate a transmembrane potential between +30 mV (at pH 7.4) and +46 mV (at pH 5.1). After treatment with amphotericin B or nystatin as ionophores, a Donnan equilibrium (D-state) will be reached with the same potential at pH 5.1 but a sharp drop down to -20 mV will occur at pH 7.4. Concerning the erythrocyte shape at these states, a stomatocyte-echinocyte transformation takes place, in correlation with the potential shift. Stomatocytes formed at delta psi greater than +25 mV, echinocytes at delta psi less than +25 mV. At potentials lower than +5 mV, no further effect can be observed. This process is reversible. Neuraminidase treatment as well as outside EDTA do not influence this process significantly. Human serum albumin in concentrations of 2% stabilizes the stomatocytes.

Amphotericin B↗
PubMed1982

Time of synthesis and cellular location of Epstein-Barr virus-specified polypeptides radioimmunoprecipitated from iododeoxyuridine-induced Burkitt lymphoma/somatic cell hybrids.

The Burkitt lymphoma/somatic cell hybrid D98/HR-1 contains repressed Epstein-Barr virus (EBV) genomes which can be induced by 5-iodo-2'-deoxyuridine (IdUrd) to express the EBV early antigen (EA) and the virus capsid antigen (VCA). Nuclear and cytoplasmic fractions prepared from uninduced, partially induced and fully induced hybrid cells were radioimmunoprecipitated with human sera having high antibody titres against EA and VCA. Three polypeptides, with mol. wt. 127 x 10(3), 115 x 10(3) and 84 x 10(3) (127K, 115K and 84K), were detected in cells induced to express EA. All three polypeptides continued to be synthesized late in infection. One of the polypeptides was predominantly nuclear, one predominantly cytoplasmic, and one found in both fractions. Three polypeptides, with mol. wt. 144K, 137K and 50K, were detectable only in cells induced to express both EA and VCA. All three polypeptides were found predominantly in the nuclear fraction.

Antigens, Viral↗
PubMed1982

[Use of dielectrophoresis for the preparative separation of thermotolerant yeast cells].

Dielectrophoresis as a new method for preparative separation of cells is being presented. This method responds to differences in the polarization of cells, which correlate with a number of complex physiological properties of cells. It is shown that yeast cells of different thermotolerant properties can be differentiated by dielectrophoresis. Moreover, the application of this method permitted to separate cells with a high selectivity, which produce more biomass at a temperature of 40 degrees C than the initial population. Investigations on the ability of cells to survive in an inhomogeneous a.c. field have shown that the number of dead cells at frequencies of 10(5) cps and 10(6) cps and at field strengths (on the surface of the central electrode) below 2.4 X 10(5) V/m is small. This fact should be considered when picking out suitable separation conditions.

Cell Separation↗
PubMed1982

Structural transitions of the erythrocyte membrane: an ESR approach.

The effect of temperature and ionic strength on the ESR spectrum of the fatty acid spin label I (10,3) in membranes of freshly drawn human red blood cells has been investigated. The results suggest that the microviscosity of the membrane is not strongly influenced by the ionic strength. Discontinuities at various temperatures could be observed, which disappear after cholesterol treatment. The possible role of membrane lipids and proteins on the thermotropic membrane behaviour observed is discussed. It is assumed that the spectra are averaged signals from different regions of the membrane.

Blood Sedimentation↗
PubMed1982

Investigations on the control of ion transport in human erythrocytes. I. Passive 86Rb efflux and possibilities of its influence.

In isotonic solutions of low NaCl concentration, human erythrocytes exhibit a strong increase of the rate constant of passive Rb+ efflux. In this range of low ionic strength the Rb+ efflux is reduced by preincubation of erythrocytes with neuraminidase, by treatment of erythrocytes with nystatin or by reduction of temperature. All these factors do not have any influence on the rate constant in solutions of physiological NaCl concentration. Ouabain (10-4 M) influences Rb+ efflux neither at low nor at physiological NaCl concentration. The results are interpreted with regard to a possible control of Rb+ efflux by surface potential and transmembrane potential.

Erythrocytes↗
PubMed1982

Investigations on the control of ion transport in human erythrocytes. II. Influence of transmembrane potential, exterior surface potential and intracellular pH on the 22Na efflux.

The rate constant of the Na+ efflux of human erythrocytes in isotonic solutions of various ionic strength varied over NaCl concentration was measured. The Na+ efflux remained constant over a wide range of ionic strength. Only under conditions where the transmembrane potential was near O mV, a local minimum could be detected. The rate constant of the ouabain-insensitive part of the Na+ efflux exhibited a strong increase at reduced exterior ionic strength. When reducing the extracellular NaCl concentration and at the same time equivalently increasing the extracellular KCl concentration in solutions of physiological ionic strength, a reduction of the rate constant of the Na+ efflux was found. It was established that an increase of the intracellular pH increases the rate constant of the Na+ efflux. A change of transmembrane potential from -7 to 52 mV at constant intracellular pH had no influence on the Na+ efflux. The change of the exterior surface potential of erythrocytes by preincubation with neuraminidase had no influence on the Na+ efflux in the range of the ionic strength studied.

Erythrocytes↗
PubMed1981

Pleiotropic expression of Epstein--Barr virus DNA in human epithelial cells.

We have attempted to establish a system that can be used to study the association of Epstein--Barr virus (EBV) with epithelial cells. Attempts were made to transfect human carcinoma cells with EBV DNA. Successful transfection was confirmed by the expression of EBV-specific early antigen (EA), virus capsid antigen, and the presence of virus DNA. The transfecting preparation contained a mixture of EBV and cellular DNA extracted from two producer cell lines, P3HR-1 and AG-876. Our data suggest that virus DNA obtained from the P3HR-1 nontransforming, EA-inducing strain of EBV was lytically expressed in the epithelial tumor cells. The DNA derived from AG-876 cells, which produce a transforming, non-EA-inducing strain of EBV, also produced a lytic infection.

Carcinoma↗