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Biomedical subjects

R Glaser

Publications and source records attributed to R Glaser.

At least 109 records · Page 6Linked to original sources
PubMed1991

The influence of valinomycin induced membrane potential on erythrocyte shape.

In addition to previous observations indicating that membrane potential changes generated by various Donnan- and Nernst-potentials lead to erythrocyte shape transformations, we show in this paper that diffusion potential change, induced by valinomycin, governs erythrocyte shape transformations. In low KCl-medium valinomycin, transferring the positive Nernst-potential into a negative diffusion potential, transforms stomatocytes into echinocytes. Using modified erythrocytes with a reversed K/Na ratio, even positive diffusion potentials can be induced by valinomycin. In these cases, stomatocytes can be generated by valinomycin. It is shown that, additionally, valinomycin in large concentrations is itself stomatocytogenic, and that the fluorescent dye diS-C3-(5) also induces stomatocytes. This, however, is a side effect which does not contradict the potential dependence of shape transformation. Using non washed erythrocytes, resuspended in plasma, valinomycin, inducing negative diffusion potential, transforms most erythrocytes to echinocytes despite the stomatocytogenic effect of albumin.

Albumins↗
PubMed1990

Expression of the Epstein-Barr virus genome in a nasopharyngeal carcinoma epithelial tumor cell line.

An epithelial tumor cell line was recently established from a biopsy specimen of a nasopharyngeal carcinoma (NPC), and designated HONE-I. Uncloned (parental) HONE-I and HONE-I clone (C)-40 cells were found to contain latent Epstein-Barr virus (EBV). Expression of the latent EBV genome in HONE-I C-40 cells has been examined. It was possible to detect a small percentage of cells spontaneously synthesizing EBV early antigen (EA) and virus capsid antigen (VCA) by immunofluorescence (IF). In addition, the EBV nuclear antigens (EBNA-I and EBNA-2), as well as the EBV latent membrane protein (LMP) were detected in the HONE-I cells. Attempts were made to induce the latent EBV genome in these cells with iododeoxyuridine (IUdR). We observed a significant increase in the number of EA/VCA-positive cells, an increase in EBV DNA, the synthesis of virus particles, and the rescue of infectious virus after treatment of HONE-I C-40 cells with IUdR. The HONE-I C-40 cells should facilitate studies of the expression and regulation of the EBV genome in NPC epithelial tumor cells, which have not previously been available.

Antigens, Viral↗
PubMed1990

Establishment and characterization of two epithelial tumor cell lines (HNE-1 and HONE-1) latently infected with Epstein-Barr virus and derived from nasopharyngeal carcinomas.

Two epithelial tumor cell lines were established from biopsy specimens of 2 nasopharyngeal carcinomas (NPC) and designated HNE-1 and HONE-1. Uncloned HNE-1 cells were found to be Epstein-Barr virus (EBV) DNA-positive when examined by Southern blot analysis up to passage 35, after which the EBV genome could no longer be detected. A similar loss of EBV DNA took place in uncloned HONE-1 cells. However, HONE-1 clone 40 cells are still EBV DNA-positive up to passage 42 thus far and cell cultures contain 85-90% EBV nuclear antigen (EBNA)-positive cells. The HNE-1 cell line has been passaged more than 100 times and the uncloned HONE-1 cells more than 90 times. The tumorigenicity of the HNE-1 and HONE-1 cells was demonstrated by tumor induction in nude mice. Karyotypic analysis of the HNE-1 cells demonstrated an aneuploidy with a modal chromosomal number of 74 at passages 5 and 101 at passage 20; 18 marker chromosomes were identified. We have continued to map the EBV genome latently associated with the HNE-1 and HONE-1 cells using the Bam HI, EcoRI or Hind III restriction enzymes. Using EcoRI fragments A-K as probes, we found that HNE-1 EBV DNA is different from B95-8 and HR-1 EBV DNA in the EcoRI-C region. The Bam HI map for HONE-1 EBV DNA is very similar to the B95-8 map; it contains the Bam HI-Y fragment but without Bam HI B' and WI'. Differences were observed between HONE-1 EBV DNA and B95-8 DNA using the Hind III restriction enzyme. There was no evidence of spontaneous expression of the latent EBV genome in HNE-1 cells, and attempts to induce replication of the latent EBV genome and rescue infectious virus have failed, suggesting a tightly restricted virus genome.

Animals↗
PubMed1990

Psychological stress-induced modulation of interleukin 2 receptor gene expression and interleukin 2 production in peripheral blood leukocytes.

We explored the expression of the interleukin 2 receptor (IL-2R) and the synthesis of IL-2R messenger RNA by peripheral blood leukocytes obtained from medical students experiencing examination stress in three independent studies. The peripheral blood leukocytes obtained at low-stress baseline periods had significantly higher percentages of IL-2R-positive cells when compared with cells obtained from the same individuals during examinations. In addition, IL2-R messenger RNA in peripheral blood leukocytes decreased significantly during examination periods in a subset of 13 subjects. In one study, we found an increase in the accumulation of interleukin 2 in cultures of cells showing down regulation of IL-2R expression and IL-2R messenger RNA levels. While there are ample data demonstrating stress-associated decrements in the immune response in humans and animals, these data provide the first evidence that this interaction may be observed at the level of gene expression. The data suggest one mechanism whereby the central nervous system modulates the immune response during psychological stress.

Adult↗
PubMed1990

Severe hemolysis after incomplete mitral valve repair.

We report 2 cases of severe intravascular hemolysis after mitral valve repair using a Duran annuloplasty ring. In both patients residual mitral regurgitation was present, hemolysis was severe enough to warrant a second operation, and hemolysis ceased immediately after the second operation. We believe that a high-velocity regurgitant jet directed toward the cloth-covered annuloplasty ring was responsible for the hemolysis in both patients.

Adult↗
PubMed1990

Psychological stress and phorbol ester inhibition of radiation-induced apoptosis in human peripheral blood leukocytes.

Apoptosis is a process of genetically programmed alterations of cell structure that lead to failure of proliferation and differentiation, and eventual cell death. Apoptosis is induced by a variety of toxic insults including growth factor deprivation and ionizing radiation. This process may function to protect against the appearance of heritable phenotypic changes in cells and may be a critical factor in normal cellular immune function. Phorbol esters inhibit apoptosis, but little is known about factors that regulate this process physiologically. In this study, we demonstrate an association between an acute psychological stressor, taking examinations, and the induction of substantial and reversible changes in the response of peripheral blood leukocytes to gamma irradiation and to phorbol ester treatment. These data suggest that psychological stress may induce physiological changes that regulate the ability of immune cells to initiate apoptosis.

Adult↗
PubMed1990

Cannabimimetic activity of novel enantiomeric, benzofuran cannabinoids.

The synthesis of the (2R,3R,4S,6R)-7/(2S,3S,4R,6S)-8 enantiomeric pair of benzofuran cannabinoids is reported together with the 1H and 13C NMR spectral parameters. In benzofuran 8 the configurational arrangement of ligated groups at the stereogenic C(3) atom (through which the terpene moiety is connected to the aromatic ring) is very similar to that of the corresponding atom in natural (3R,4R)-delta 1-tetrahydrocannabinol (delta 1-THC), although their respective Cahn-Ingold-Prelog descriptors are different. In drug-discrimination tests in pigeons and rats, benzofuran 8 is as active as delta 1-THC; in the mouse ring test compound 8 is more active than delta 6-THC. Enantiomer 7 is considerably less active than enantiomer 8 in both tests. These results can be explained by the fact that both 7 and 8 have a dimethylheptyl side chain (which is known to enhance cannabimimetic activity) and that delta 1-THC and benzofuran 8 have closely related conformations, as determined by molecular mechanics.

Animals↗
PubMed1990

A monoclonal antibody that neutralizes Epstein-Barr virus, human cytomegalovirus, human herpesvirus 6, and bacteriophage T4 DNA polymerases.

A monoclonal antibody (mAb) designated 55H3 was produced by using chemically induced Epstein-Barr virus genome-positive B95-8 cells. mAb 55H3, which reacted with an 85- to 80-kDa polypeptide, neutralized Epstein-Barr virus-encoded DNA polymerase activity in crude extracts of chemically induced M-ABA, HR-1, and B95-8 cells, as well as the partially purified Epstein-Barr virus DNA polymerase in a dose-dependent manner. The mAb also neutralized the virus-encoded DNA polymerase activity from cells infected with human cytomegalovirus, human herpesvirus 6, and the purified bacteriophage T4 DNA polymerases. However, mAb 55H3 did not neutralize the DNA polymerase activities encoded for by herpes simplex virus types 1 and 2, the reverse transcriptase of avian myeloblastosis virus, or Escherichia coli DNA polymerase 1 (Klenow fragment). These results suggest that mAb 55H3 recognizes an epitope common to some herpesviruses and T4 DNA polymerases and further supports the hypothesis that these organisms are evolutionarily related.

Animals↗
PubMed1990

A monoclonal antibody that neutralizes Epstein-Barr virus DNA polymerase activity.

An Epstein-Barr virus (EBV) specific monoclonal antibody (MAb), designated 55H3, was produced after immunizing BALB/c mice with 12-O-tetradecanoylphorbol-13-acetate (TPA) activated B95-8 cells. It was possible to demonstrate that this MAb detected an EBV-specific antigen(s) in the EBV genome-positive producer cell lines B95-8 and M-ABA by immunofluorescence. Immunoglobulin prepared from ascites fluid neutralized the activity of the EBV-encoded DNA polymerase, but not the alkaline DNase. By Western blotting, the 55H3 MAb reacts with an 85/80-KD polypeptide. The 55H3 should be useful in examining the role of EBV DNA polymerase in viral replication.

Animals↗
PubMed1990

Species-dependent differences in the influence of ionic strength on potassium transport of erythrocytes. The role of membrane fluidity and Ca2+.

The passive Rb+ (K+) efflux from erythrocytes of seven mammalian species was investigated in solutions of physiological and low ionic strength. Furthermore the fluidity of the erythrocyte membrane in the same solutions was estimated by measuring the ESR order parameter. The rate constant of Rb+ (K+) efflux in solution of high ionic strength could be correlated with the order parameter obtained and with the mean number of double bonds to the membrane phospholipid fatty acids. The same relationships could be observed for the low ionic strength solutions if the values for human erythrocytes were excluded. The appearance of Na+, K+, Cl- cotransport to a significant extent, only in human erythrocytes, was supposed to be the reason for this different behaviour of human red blood cells. It was demonstrated that the strong increase of the Rb+ (K+) efflux rate constant for human erythrocytes in low ionic strength solution is not due to Ca2+, as quinine treatment and replacement of all external potassium, both inhibiting the Ca2(+)-induced K+ efflux, did not abolish the increase of (Rb+) K+ efflux in solutions of low ionic strength.

Animals↗
PubMed1989

The transforming prototype of Epstein-Barr virus (B95-8) is also a lytic virus.

The B95-8 isolate of the Epstein-Barr virus (EBV) has been described as a non-lytic transforming virus. We have performed experiments in order to determine if the B95-8 EBV is capable of super-infecting and replicating in EBV-genome-positive non-producer lymphoblastoid cells. Using concentrates of B95-8 EBV, prepared from 6 different B95-8 cell lines treated with 12-O-tetradecanoylphorbol-13-acetate (TPA), we demonstrated that virus concentrates could transform human or cotton-top tamarin B-lymphocytes and also lytically replicate in Raji cells, inducing EBV antigens and infectious virus. While the virus obtained from B95-8 super-infected Raji cells was able to transform cord-blood lymphocytes (CBLs) and super-infect Raji cells, transformation was abortive, with cell cultures only growing for up to 6 weeks. Transformation titers of the B95-8 virus concentrates ranged from 10(5) to greater than 10(8) transforming units/ml; early antigen (EA) induction ranged from 1% to 50% after superinfection of Raji cells, depending on the virus stock used, as determined by immunofluorescence. Southern blot analysis was carried out on the DNA prepared from B95-8 cells and virion DNA. The results were consistent with the published EcoRI restriction pattern for B95-8 EBV. The issue of whether the B95-8 cells produce virions with a dual biological phenotype or, rather, 2 biologically distinct viruses, is addressed.

Cell Line↗
PubMed1989

Sister chromatid exchange and nasopharyngeal carcinoma.

Sister chromatid exchange (SCE) is a genetic indicator of DNA damage in mammalian cells and may afford a sensitive monitor to follow genomic instability of some individuals with fragile chromosomal diseases or malignancies. In studies on the effect of dinitrosopiperazine (DNP), aflatoxin B1 (AFB1), methyl-nitro-nitroso-guanidine (MNNG) and Epstein-Barr virus (EBV) infection on SCE in lymphocytes from nasopharyngeal carcinoma (NPC) patients, we found that: (1) the spontaneous SCEs in peripheral blood lymphocytes (PBLs) from 75 NPC patients were significantly higher than those of PBLs from 44 normal adults, 24 cord blood (CBL) specimens, and PBLs from 20 patients with chronic inflammation of the nasopharynx; (2) PBLs from NPC patients who were positive for EBV virus capsid antigen (VCA) IgA antibody had a higher SCE frequency as compared with PBLs from VCA IgA-negative NPC patients; (3) the chemical carcinogens used induced significantly higher SCEs in lymphocytes from NPC patients than in PBLs from normal adults and CBLs; (4) the mean SCEs of EBV growth-transformed CBLs increased from 5.17 to 14.12 after infection and was similar to the level of SCEs found in PBLs from the VCA IgA-positive NPC patients. The data suggest that lymphocytes of NPC patients might be more fragile than the lymphocytes of the control groups studied.

Adult↗
PubMed1989

Predilection of a nasopharyngeal carcinoma-derived isolate of Epstein-Barr virus for infection of specific subsets of B lymphocytes.

It is important to know whether there are variants of Epstein-Barr virus (EBV) with biological properties that are different from the prototype viruses that have been studied in detail, such as P3HR-1 and B95-8. We have studied an EBV isolate derived from a nasopharyngeal carcinoma (NPC) tumor, designated NPC-EBV. We have examined the target B lymphocytes infected and growth-transformed with NPC-EBV as compared with two common EBV isolates, B95-8 and AG876 EBV, for stage of maturation using antibodies to several immunoglobulin chains. Typing of the NPC-EBV transformed lymphoblastoid cell lines revealed the predilection of the NPC-EBV isolate to infect immature B lymphocytes. This was not the case for the B95-8 and AG876 isolates. The reason for the predilection of NPC-EBV for immature B lymphocytes remains to be explored further. However, these results may be important in understanding the pathophysiology of EBV-associated diseases.

Animals↗
PubMed1989

Stereoisomer differentiation for the analgesic drug nefopam hydrochloride using modeling studies of serotonin uptake area.

Equatorial and axial N-methyl diastereomers of the analgesic drug nefopam hydrochloride were differentiated using a hypothetical model of the serotonin (5-hydroxytryptamine) uptake area. Both diastereomers were placed within the hypothetical model area to form van der Waals interactions involving the phenyl group of nefopam, but only in the case of the equatorial N-methyl epimer was the +N--H bond able to be oriented towards the proposed hydrogen-bonding site. A comparison of equatorial N-methyl nefopam hydrochloride enantiomers in the proposed two-site binding mode points to less severe nonbonding steric interactions for the (+)-(1S,5S)-enantiomer compared with the (-)-(1R,5R)-isomer.

Models, Biological↗
PubMed1989

Demonstration of the human herpesvirus 6-induced DNA polymerase and DNase.

Infection of HSB-2 cells with human herpesvirus 6 (HHV6) results in an approximately 51-fold increase in the level of DNA polymerase activity and a 4.44-fold increase in the level of DNase activity when compared to mock-infected cells. There was no increase in thymidine kinase, uracil-DNA glycosylase, or deoxyuridine triphosphate nucleotidohydrolase activities in the infected cells. The HHV6-induced DNase and DNA polymerase activities could be distinguished from their normal cellular counterparts on the basis of immunological specificities and in the case of DNA polymerase based upon differences in electrophoretic migration. Serological studies also demonstrated reactivity of the antisera not only for HHV6 but also for Epstein-Barr virus.

Cell Line↗
PubMed1989

Epstein-Barr virus DNA in nasopharyngeal biopsies.

The Epstein-Barr virus (EBV) has been closely associated with the undifferentiated form of nasopharyngeal carcinoma (NPC), which is particularly common in the high risk area in southeast China. We have examined 37 nasopharyngeal biopsies from patients within this high risk area, including 31 cases of undifferentiated NPC and 6 cases of patients with nasopharyngitis, for the presence of EBV DNA. We found that 26 of 31 biopsies from NPC patients were EBV DNA positive; 3 of the 6 biopsies from patients diagnosed with nasopharyngitis were also EBV DNA positive. Southern blot analysis of the DNAs obtained from the EBV genome positive biopsies, digested with EcoRI, showed that all preparations from the NPC tumors had only one band corresponding to the EcoRI A fragment when a BamHI W fragment was used as a probe. However, one tumor had an additional band with a molecular weight larger than EcoRI A. The presence of this novel band could indicate the integration of viral DNA into host cellular DNA. DNA from the same biopsies were restricted with BamHI and PstI restriction enzymes. The data obtained from these experiments suggest that the EBV genomes in both the NPC tumor biopsies and biopsies from nasopharyngitis patients obtained from an endemic area in South China may be similar to each other and to the B95-8 EBV isolate with respect to the BamHI Y region of the EBV genome. The data also demonstrate that infection of normal nasopharyngeal epithelial cells with EBV takes place in patients with nasopharyngitis.

Biopsy↗