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Biomedical subjects

S St Jeor

Publications and source records attributed to S St Jeor.

At least 37 records · Page 2Linked to original sources
PubMed1994

Human cytomegalovirus alters interleukin-6 production by endothelial cells.

In an effort to study whether human cytomegalovirus (HCMV) can disrupt the balanced cytokine network that controls human hematopoiesis, we investigated the ability of a laboratory strain HCMV (AD169) to alter the production of interleukin-6 (IL-6) by cultured endothelial cells (HUVECs). ECs are important components of human bone marrow stroma and produce factors that stimulate the proliferation and differentiation of human hematopoietic progenitors. HCMV was able to greatly increase production of both mRNA and protein for IL-6 in unprimed HUVECs. When we discriminated between viral pellet and cleared viral supernatants, the supernatants induced an increase in mRNA at 30 minutes and protein by 2 hours, whereas an increase in IL-6 caused by virus itself did not become evident until 12 hours. The possibility that IL-6 induction was simply caused by the presence in the viral stock of endotoxin, IL-1 alpha, IL-1 beta, tumor necrosis factor alpha, or IL-4, all known inducers of IL-6 in HUVECs, was ruled out by the addition of polymyxin B and appropriate neutralizing antibodies. These findings show that HCMV is capable of directly and indirectly modulating the production by HUVECs of IL-6, one of the cytokines involved in the process of hematopoiesis.

Cells, Cultured↗
PubMed1993

Infection of mononucleated phagocytes with human cytomegalovirus.

Human cytomegalovirus (HCMV) can be isolated from peripheral blood leukocytes; however, in vitro, only abortive infection of monocytes, lymphocytes, and granulocytes has been detected. These studies demonstrate that freshly isolated monocytes can be infected with HCMV. Infection of monocytes was not associated with loss of cell viability. The virus replication cycle in monocytes resembled that observed in fibroblasts but the virus yield was approximately 0.1% of that observed in fibroblasts. Transient phenotypical changes occurred in HCMV-infected monocytes. Virus persists in infected monocytes upon differentiation to macrophages, suggesting that monocytes may serve as a carrier of HCMV and a vector for viral dissemination. Differentiated mononuclear phagocytes appear to support a productive HCMV infection. Using a recombinant HCMV strain to express beta-galactosidase, we were able to transduce the bacterial beta-galactosidase gene into monocytes and macrophages.

Antigens, Viral↗
PubMed1993

Suppression of normal human hematopoiesis by cytomegalovirus in vitro.

Human cytomegalovirus (HCMV) infection is associated with marrow suppression in immunocompromised patients. To examine the mechanism(s) underlying this suppression, the effect of a laboratory strain of HCMV (AD169) and a clinical isolate of HCMV on colony formation by normal human marrow (BMC) hematopoietic progenitors in the presence and/or absence of monocyte/macrophages (MO) and T cells was studied. Direct addition of HCMV at multiplicity of infection (MI) of 0.1 to 5 to BMC produced dose-dependent inhibition of colony forming unit-mix (CFU-Mix) (30-82%), CFU granulocyte, macrophage (CFU-GM) (15-98%), and burst forming unit-erythroid (BFU-E) (23-86%); no consistent effect of CFU-erythroid (CFU-E) was noted. This inhibition occurred both with the direct addition of HCMV to the culture plates as well as by the preincubation of BMC with HCMV followed by washing of the cells; significant inhibition (p < 0.01) of colony formation occurred after 1 hour of incubation at MI of 5. No suppression of colony formation occurred when UV-irradiated virus was used. The inhibitory effect of HCMV was reduced when MO and T cells were removed prior to exposure of marrow to virus at MI of 1 to 5. At MI of 20, however, HCMV suppressed colony formation by BMC depleted of MO and T cells by about 40%. Coculture of autologous or allogeneic T cells, but not MO, exposed to HCMV with intact or depleted marrow resulted in inhibition of CFU-Mix (51%), CFU-GM (40%), and BFU-E (37%). The inhibitory effect of virus-exposed T cells did not appear to be mediated through a soluble factor. T cells expressing CD8 antigen were most active in this process; natural killer (NK) cells were not active. These results suggest that the suppressive effect of HCMV on hematopoiesis may be mediated in part through T lymphocytes.

Antibodies, Viral↗
PubMed1984

Enhancement of deoxyguanosine kinase activity in human lung fibroblast cells infected with human cytomegalovirus.

Studies were conducted to establish the relationship between deoxyguanosine kinase activity and human cytomegalovirus (HCMV) infection. Using both PAGE and isoelectric focusing techniques, extracts from untreated and infected cells were examined for deoxyguanosine kinase activity. The analyses resulted in identical migration rates for deoxyguanosine kinase activity in both infected and uninfected extracts. These data and kinetic studies based on apparent Km values suggest that HCMV enhanced a cellular kinase activity rather than coded for a virus specific enzyme. Furthermore, our results indicated that infected cells, like normal fibroblasts, contain two deoxyguanosine kinase activities, one of mitochondrial and another of cytosolic origin. Of particular interest was the observation that HCMV infection caused an enhancement of the mitochondrial enzymatic activity while the cytosolic activity showed no change. Deoxycytidine kinase activity which is associated with cytosolic deoxyguanosine kinase was unaffected by HCMV infection.

Cells, Cultured↗
PubMed1982

Isolation of infectious bovine rhinotracheitis virus from the soft-shelled tick, Ornithodoros coriaceus.

Infectious bovine rhinotracheitis virus was isolated from the soft-shelled tick (Ornithodoros coriaceus). Serological identification of the isolated viruses was confirmed by restriction endonuclease digestion of purified virus DNA. These isolations indicate that the soft-shelled tick may be a vector for infectious bovine rhinotracheitis virus. This may be the first reported isolation of mammalian herpesvirus from an arthropod vector.

Animals↗
PubMed1982

Analysis of human cytomegalovirus nucleoprotein complexes.

When chromatin was isolated from cells infected with human cytomegalovirus, the virus DNA remained with the chromatin fraction. If deproteinized virus DNA was added to either isolated nuclei or chromatin, the DNA was lost during the chromatin isolation. When isolated chromatin from cytomegalovirus-infected cells was banded in isopycnic metrizamide gradients, a single peak with a density of 1.18 g/cm3 was present. Analysis of this peak in isopycnic neutral CsCl gradients indicated that it contained both human cytomegalovirus and human embryonic lung cell DNAs. When infected nuclei were treated with micrococcal nuclease, 11S subunit particles which cosedimented with cell nucleosomes and contained virus DNA were isolated.

Chromatin↗
PubMed1981

Transcription of the human cytomegalovirus genome in productively infected cells.

Nuclear and cytoplasmic RNAs, synthesized in cells productively infected with human cytomegalovirus (HCMV) were analysed at various times after infection by liquid and filter DNA-RNA hybridization. Results of these experiments have revealed that: (i) the fraction of the genome transcribed increased as infection progressed. In the nucleus, transcripts represented approx. 20% of the virus DNA sequences at both 2 and 4 h post-infection (p.i.) and 36% of the virus DNA at 40 h p.i; (ii) the increase in virus sequences among nuclear transcripts at late times was prevented by the DNA synthesis inhibitor, 2'-deoxyfluorouridine; (iii) early virus RNA transcripts were subset of those represented in late RNA; (iv) two classes of early RNA were identified by competition hybridization; (v) approx. 10% of the late nuclear transcripts were symmetrical. Results of filter hybridization at DNA excess indicated that virus-specific RNA represented 0.6% of RNA labelled from 0 to 2 h p.i., and 1.8% of RNA labelled from 28 to 30 h. Polyadenylated RNA isolated from cytoplasm represented 1.2% and 10% of labelled mRNA at 2 h and 30 h respectively. Our data show that during productive infection of human cells by HCMV, gene expression is under temporal, quantitative and post-transcriptional control.

Cells, Cultured↗
PubMed1979

Hypocholesterolemic effect of yogurt and milk.

In order to determine the effect of milk products on serum cholesterol, triglycerides, and diet, 54 volunteers were studied for varying periods with dietary supplementation of nonpasteurized yogurt, pasteurized yogurt and 2% butterfat milk. Serum cholesterol was significantly reduced by 5 to 10% after 1 week of supplementation with either nonpasteurized or pasteurized yogurt; 2% butterfat milk reduced serum cholesterol to a smaller and less significant effect. Serum triglycerides were unaffected by the diet and dietary intake studies confirmed that intake of other nutrients remained relatively stable throughout the study. Supplementation of diet with yogurt may have a helpful hypocholesterolemic effect.

Adult↗
PubMed1978

Cell DNA induction by human cytomegalovirus.

The studies presented indicate that in cells pretreated with IUDR: (1) a temporal relationship exists between CMV and cell DNA synthesis; (2) in cells pretreated with IUDR only a fraction of the cell genome is induced by the virus to replicate; and (3) cell DNA induced by the virus to replicate represents unique rather than repetitive DNA sequences.

Base Sequence↗
PubMed1977

Partial characterization of a herpes-type virus (K9V) derived from Kaposi's sarcoma.

A herpes-type virus that was originally isolated from a cell culture (designated K9V) derived from a tumor biopsy specimen from a patient with Kaposi's sarcoma was partially characterized. The host range of K9V, as determined by the induction of virus-specific cytopathology, synthesis of antigens, and plaque formation, was limited to human cells and particularly to fibroblasts. Immunofluorescence and complement fixation assays confirmed the specificity of the presence of cytomegalovirus (CMV)-type antigens in K9V-infected human fibroblasts. In addition, the density of K9V DNA was consistent with the density of CMV DNA. However, some peculiarities were observed in the K9V strain of CMV. The virus seemed more cell-associated in human fibroblasts than were known laboratory strains: The spread of cytopathology was slow and did not always involve the whole cell sheet, and the total regression of cytopathology with the establishment of a persistent infection was common. Similar characteristics have recently been observed in the Mj strain of CMV, which has been shown to be oncogenic in human fibroblasts.

Antigens, Viral↗
PubMed1977

Comparison of the polypeptides of several strains of human cytomegalovirus.

Analysis of purified human cytomegalovirus (CMV) by sodium dodecyl sulphate-polyacrylamide gel electrophoresis revealed 32 polypeptides with mol. wt. ranging from 13,500 to 235,000. Similar analysis of purified preparations of four strains of CMV showed a remarkable similarity in polypeptide composition. Results indicate that the four strains may be related.

Cell Line↗
PubMed1977

Persistence of cytomegalovirus in human lymphoblasts and peripheral leukocyte cultures.

The in vitro susceptibility of human peripheral lymhpocytes and lymphoblastoid (F265) cells to infection by human cytomegalovirus was examined. Infection of these cell types with cytomegalovirus resulted in a persistent type of infection rather than the typical growth curve observed with permissive fibroblastic cells. When infection of peripheral lymphocytes was associated with a blastogenic response, the virus persisted for a longer time and at a higher titer than in cells in which a blastogenic response did not occur. Autoradiographic studies and infectious-center assays indicated that only a small number of cells, resembling lymphocytes, were involved in virus persistence. Whether or not the persistence of the virus indicates release of input virus or synthesis or new virus was not determined.

Cell Line↗
PubMed1976

The development by cytomegalovirus-infected cells of binding affinity for normal human immunoglobulin.

After infection with human cytomegalovirus (CMV), cells develop an affinity for normal human immunoglobulin G (IgG). This was demonstrated using 125iodine-labeled purified IgG. It was further demonstrated that the immunoglobulin molecule binds to CMV-infected cells via its Fc portion, and competition for binding to infected cells occurred between purified preparations of human IgG and the Fc fragment of human IgG. Whole sera from individuals with or without a high titer of anti-CMV antibody were labeled with 125iodine and it was demonstrated that serum from individuals with no anti-CMV antibody had an affinity for CMV-infected cells which probably reflected binding of IgG via its Fc fragment. The possible significance of these results in immunologic studies of human CMV is considered.

Antibodies, Viral↗