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Biomedical subjects

H Rollag

Publications and source records attributed to H Rollag.

At least 19 recordsLinked to original sources
PubMed1999

Immunologic parameters as predictive factors of cytomegalovirus disease in renal allograft recipients.

Cytomegalovirus (CMV) disease is a major problem in renal transplant recipients, but few predictive markers of the disease are known. Several immunologic parameters of potential relevance for the defense against CMV were measured after renal transplantation in 25 patients before any manifestations of CMV infection occurred. In 10 patients who later developed CMV disease, plasma levels of interleukin-8 were significantly higher, whereas the levels of macrophage inflammatory protein-1alpha (MIP-1alpha) were significantly lower than in 15 patients who did not develop CMV disease. Also, lower numbers of CD4+ and CD8+ lymphocytes were observed in patients who later had CMV disease. These findings were independent of previous rejection therapy and were particularly pronounced in patients with primary CMV infection. Interleukin-8 and MIP-1alpha may be predictive markers of CMV disease and could be of potential use in selecting patients for prophylactic treatment.

Adult↗
PubMed1998

Diagnosis of cytomegalovirus infection in kidney transplant recipients by a quantitative RNA-DNA hybrid capture assay for cytomegalovirus DNA in leukocytes.

The clinical value of a new RNA-DNA hybridization assay for quantification of cytomegalovirus (CMV) DNA in leukocytes [Hybrid Capture CMV DNA Assay (HCA); Murex Biotech, UK] was evaluated. The HCA was compared with an assay for CMV pp65 antigen in leukocytes and an in-house CMV polymerase chain reaction PCR (CMV-PCR) on parallel blood samples. The HCA and the CMV-PCR were less sensitive than the CMV pp65 assay, but the positive predictive value of all three methods for CMV disease was 50% or less. However, when quantitation of viral load by HCA and CMV pp65 assay was taken into consideration, both assays were superior to CMV-PCR in predicting CMV disease.

Antibodies, Monoclonal↗
PubMed1998

Viral safety of blood derivatives by immune neutralization.

Despite careful donor selection and virus inactivation procedures, transmission of viruses by transfusion of blood and blood derivatives is still a threat. Outbreaks of hepatitis A among hemophiliacs having received highly purified, immune globulin depleted coagulation factor concentrates, put the importance of immune neutralization of viruses in blood derivatives in focus. Neutralizing antibodies may block several steps in the virus infection of a cell, from binding of virus to the cellular receptor to the uncoating of virus after uptake in the cell. The efficacy of antibody neutralizing activity depends on the availability and stability of the neutralizing epitopes. Hepatitis A and B viruses are very efficiently neutralized by antibodies and immune escape mutants rarely emerge. Anti-parvovirus B19 antibodies do not fully inactivate the virus, at least in low concentrations, but may prevent development of disease. The neutralizing epitopes on hepatitis C virus and human immunodeficiency virus are located on hypervariable regions of virus membrane proteins. The effects of neutralizing antibodies are thus marginal as immune escape mutants emerge at a relatively high frequency for both viruses. The neutralizing activity of anti-cytomegalovirus antibodies is also questionable as persons may become reinfected with cytomegolvirus despite high levels of antibodies. Plasma and plasma derivatives produced from large donor pools have the potential of being very efficient transmitters of viruses. Neutralizing antibodies are Nature's own, and very important barriers against the spread of many known and unknown viruses contaminating the plasma pools.

Antibodies, Viral↗
PubMed1998

Interaction of herpes simplex virus with mononuclear phagocytes is dependent on the differentiation stage of the cells.

The interaction of herpes simplex virus (HSV) with mononuclear phagocytes (MP), i.e. monocytes and macrophages, is of importance for the pathogenesis of HSV infections. MP are known to play a significant role in the cellular defence against infections with HSV, but it has also been shown that HSV-1 affects MP. The infection of these cells at different stages of differentiation has different outcomes, and may result in the alteration of important cellular functions. HSV-1 inhibits the morphological differentiation of human monocytes, and this inhibition occurs in spite of the fact that human monocytes are non-permissive to HSV-1. We have studied the effect of HSV infection of monocytes and macrophages on production of essential cytokines and related this effect to the reproduction of the virus. Blood-derived MP were cultured in vitro and inoculated with HSV at different stages of differentiation. Replication of the virus was measured by infectivity titration, detection of HSV antigens by immunofluorescence and detection of HSV-specific mRNA. In monocytes, no viral replication and no production of late protein was seen. HSV IE gene was transcribed in monocytes from some donors, but not from others. In macrophages, virus replicated, but less efficiently than in fully permissive fibroblast cells. The production of IL-1 beta, IL-6 and TNF-alpha in both non-permissive monocytes and permissive macrophages was assayed both at the transcriptional level, as mRNA, and as protein released from the cells. Production of cytokines by MP was affected by HSV-1. The level of cytokine mRNA and cytokine protein did not correspond for all cytokines, which may suggest that translational regulation and/or cytokine inhibitors are important in the regulation of the cytokine response. The cytokine modulation, both at the transcriptional level and measured as biological activity, was different in monocytes and macrophages, and varied between different donors. Our results indicate a relation between permissiveness and cytokine response in mononuclear phagocytes infected with HSV-1. Such a relation may be of importance to both intrinsic and extrinsic defence mechanisms of MP against HSV-1. Our study also demonstrates that even the functions of non-permissive cells such as blood-derived monocytes may be affected by viral infections.

Cell Differentiation↗
PubMed1998

Herpes simplex virus type 1 inhibits in vitro differentiation and selected functions of human blood-derived monocytes.

We have studied the effect of herpes simplex virus type 1 (HSV1) infection on in vitro differentiation of blood-derived human monocytes into macrophages using morphological, functional and biochemical parameters that alter during macrophage differentiation. Purified preparations of HSV modified the monocyte-macrophage differentiation, in spite of the fact that the virus did not replicate in monocytes. Disappearance of expression of a monocyte-specific surface antigen and the typical development of morphological appearance were delayed in HSV- infected cells. Production of the lysosomal enzyme acid phosphatase, which normally increases during differentiation, was also reduced in infected cells. Transcription of the oncogenes c-myc and c-fos, and the Hsp70 gene was modified in cells from some donors but not in other cell preparations. Possible mechanisms of these effects are discussed.

Acid Phosphatase↗
PubMed1997

Infection with human cytomegalovirus (HCMV) stimulates monocyte production of complement factor 3.

Complement biosynthesis in monocytes is stimulated by different microorganisms including Gram negative bacteria and yeasts. We have tested the effect of human cytomegalovirus (HCMV) on complement factor 3 (C3) production by cultured human monocytes. The monocytes were challenged with either a crude or a purified HCMV preparation obtained from the supernatant of HCMV-infected fibroblasts. When the monocytes were infected with 2 pfu/cell of virus and cultured for 2 days, the increase in C3 production compared to control ranged from 3% to 162%, median 62% (p < 0.01). However, crude HCMV was even more potent in stimulating C3 production, as the increase in C3 values ranged from 104% to 507%, median 247% (p = 0.001). This indicates the presence in the crude HCMV preparation of a substance which acts synergistically with HCMV on the C3 production. When monocytes were stimulated by lipopolysaccharide (LPS), a well known inducer of C3, infection with crude or purified HCMV did not further increase C3 production. Both HCMV and substances produced during the propagation of HCMV in fibroblasts are able to stimulate C3 production in monocytes. Complement production by inflammatory cells may be of importance in host resistance against viral infections.

Cell Line↗
PubMed1997

The human polyomavirus BK T antigen induces gene expression in human cytomegalovirus.

Co-infections or co-habitations of cells by two or more viruses may occur in the human organism. Human cytomegalovirus (HCMV) and the human polyomavirus BK (BKV) have common host cells and may both establish lifelong latency/persistence following primary infection. Both viruses may become reactivated by immunosuppression or other conditions which upset host-virus balance, and they encode gene products with the inherent potential of acting as heterologous transacting factors for expression of cellular or viral genes. It has been shown that HCMV induces gene expression and replication of primate polyomaviruses. We now demonstrate that BKV is able to enhance the expression of HCMV immediate early (IE1 and 2) as well as the early (E) protein pp65 during double infections in semi-permissive cells. By transfection experiments it was established that the phenomenon is due to heterologous transcriptional transactivation of the HCMV major IE promoter (MIEP) by the BKV large T antigen, without contribution from the small t antigen.

Antigens, Viral, Tumor↗
PubMed1997

The effect of human cytomegalovirus on selected functions of peripheral blood monocytes.

The effect of in vitro infection of human cytomegalovirus (HCMV) on various monocyte functions relevant to antimicrobial defence mechanisms has been investigated: the phagocytic activity of monocytes, the release of lysozyme and intracellular concentration of acid phosphatase, and the release of the cytokines interleukin-1 (IL-1), IL-6, and tumour necrosis factor-alpha (TNF-alpha). HCMV significantly inhibited the release of lysozyme and intracellular concentration of acid phosphatase. Regarding the phagocytic activity and the release of cytokines, there was considerable variation in the HCMV effect among the different blood donors tested. There was no clear tendency in the observed results; both stimulation and inhibition were seen. The HCMV-specific pp65 was detected in the nucleus of about 1% of the monocytes 3 h after infection and HCMV-specific IE antigens were found in about 0.1% of the monocytes 2 days postinfection. No E- or L-gene expression was observed and no infectious virus was produced in the monocytes. Our results indicate that HCMV infection may influence monocyte functions in spite of no productive infection of these cells.

Cytomegalovirus↗
PubMed1997

Effect of adenovirus 2 on cellular gene activation in blood-derived monocytes and macrophages.

We have investigated the effect of adenovirus 2 (Ad2) infection on human monocytes and monocyte-derived macrophages with regard to expression of TNF-alpha and IL-1 beta. In monocytes, the virus was bound to the surface without being internalized. On the other hand, Ad2 was internalized by macrophages. No virus replication and no transcription of the Ad2 early genes was observed in either of the cells. Ad2 infection induced transient increase in the mRNA levels for TNF-alpha and IL-1 beta in both monocytes and in macrophages, although the kinetics of the transcription was slightly different. The production of both cytokines, measured by ELISA tests, was enhanced in monocytes. In macrophages, a slight enhancement of TNF-alpha production was seen, whereas IL-1 beta was not detected. The data indicate that cellular genes might be activated by Ad2 virus infection in nonpermissive cells where no viral gene products could be detected.

Adenoviridae↗
PubMed1997

Modification of mononuclear cell function after incubation with albumin-bound unsaturated fatty acids or soybean oil emulsion.

Administration of total parenteral nutrition (TPN) with soybean oil emulsion leads to a linoleic acid enrichment of the plasma membrane that may explain an in vivo activation of mononuclear cells (MNC) seen in our previous studies. Fatty acids from the lipid emulsion may have been accessible to MNC after endocytosis of lipid particles, or by direct uptake of fatty acids after lipoprotein lipase hydrolyzation of the emulsion triglycerides. To resemble the incorporation of fatty acids in vivo, we have modified MNC membrane lipid composition by incubation with different albumin-bound unsaturated fatty acids (UFA) or soybean oil emulsion. After incubation with albumin-bound linoleic and oleic acid, the unstimulated release of superoxide anion was unchanged, while zymosan-stimulated release was 140% (n.s) and 112% (p < 0.05) and phorbol-myristate-acetate (PMA)-stimulated release 148% (p < 0.05) and 124% (p < 0.05) of controls, respectively. Incubation with other UFAs or emulsion did not change superoxide anion release. Unstimulated lymphocyte proliferation increased 3 to 13-fold (p < 0.05) after incubation with all UFAs compared to controls, while UFA incubation did not change phytohemagglutinin (PHA) or PMA-stimulated proliferation. Unstimulated lymphocyte proliferation was decreased after incubation with emulsion, while PHA/PMA-stimulated proliferation was unchanged. Increase in membrane fluidity was detectable only after incubation with emulsion. The increased reactivity may have been caused by changes in the lipid environment surrounding membrane-bound enzymes important for signal transduction through the plasma membrane.

Cells, Cultured↗
PubMed1996

Human cytomegalovirus suppression of and latency in early hematopoietic progenitor cells.

Bone marrow cells (BMC) are involved in the pathogenesis of human cytomegalovirus++ (HCMV) infections, and the hematopoietic cells are probable sites of HCMV latency in healthy donors. In vitro studies have indicated both a direct inhibitory effect of HCMV on proliferation and differentiation of myeloid bone marrow progenitors and an impairment of bone marrow stroma cell function by HCMV. The purpose of the present study was to establish whether the suppressing effect could be limited to subsets of immature CD34+ BMC and to investigate the role of immature cell populations as possible sites of HCMV latency. CD34+ cells from healthy HCMV-seropositive and -seronegative donors were sorted according to the expression of HLA-DR (CD34+ HLA-DR+ and CD34+ HLA-DR- cells). The progenitor growth of hematopoietic progenitor cells from seronegative donors was examined by colony and single-cell assays after in vitro infection with HCMV. To determine the susceptibility of the CD34+ cells to HCMV infection in vitro and in vivo, cells of both subsets from seronegative and seropositive donors were analyzed for the presence of HCMV DNA by polymerase chain reaction. HCMV infection in vitro inhibited the interleukin-1alpha (IL-1alpha)-, IL-3-, granulocyte colony-stimulating factor-, granulocyte-macrophage colony-stimulating factor-, and stem cell factor-induced proliferation in single-cell assays of CD34+ HLA-DR- cells by 34%. In contrast, the colony growth of the CD34+ HLA-DR+ subset was suppressed in cells from only 3 of the 8 donors. However, in vitro HCMV infection of the CD34+ HLA-DR+ progenitor cells inhibited the proliferation of all donors tested when hematopoietic growth factors were used individually to promote progenitor growth. In addition, the formation of burst-forming units-erythroid and colony-forming units-granulocyte, erythrocyte, monocyte, megakaryocyte was reduced 40% to 60% by HCMV in vitro. In contrast, the growth of high proliferative potential colony-forming cells was not inhibited after in vitro HCMV infection. Furthermore, HCMV DNA was detected in both CD34+ HLA-DR- and CD34+ HLA-DR+ progenitors from in vitro-infected HCMV-seronegative donors and cells from HCMV-seropositive donors. Taken together, the early progenitors defined as CD34+ HLA-DR- and CD34+ HLA-DR+ are directly suppressed in their proliferation by HCMV in vitro, and hematopoietic stem cells are also sites of HCMV latency in healthy HCMV-seropositive donors.

Adult↗
PubMed1996

Direct growth suppression of myeloid bone marrow progenitor cells but not cord blood progenitors by human cytomegalovirus in vitro.

Recently, considerable interest has arisen as to use cord blood (CB) as a source of hematopoietic stem cells for allogenic transplantation when bone marrow (BM) from a familial HLA-matched donor is not available. Because human cytomegalovirus (HCMV) has been shown to inhibit the proliferation of BM progenitors in vitro, it was important to examine whether similar effect could be observed in HCMV-infected CB cells. Therefore, the effect of HCMV challenge on the proliferation of myeloid progenitors from BM and CB was compared using both mononuclear cells (MNC) and purified CD34+ cells. A clinical isolate of HCMV inhibited the colony formation of myeloid BM progenitors responsive to granulocyte-macrophage colony-stimulating factor (CSF), granulocyte-CSF, macrophage-CSF, interleukin-3 (IL-3) and the combination of IL-3 and stem cell factor (SCF). In contrast, colony growth of CB progenitors was not affected. In addition, HCMV inhibited directly the growth of purified BM CD34+ cells responsive to IL-3 and SCF in single cell assay by 40%, wheras the growth of CD34+ progenitors obtained from CB was not suppressed. The HCMV lower matrix structural protein pp65 and HCMV DNA were detected in both CB and BM CD34+ cells after in vitro challenge. However, neither immediate early (IE)-mRNA nor IE proteins were observed in infected cells. Cell cyclus examination of BM and CB CD34+ cells revealed that 25.7% of BM progenitors were in S + G2/ M phase wheras only 10.7% of the CB progenitors. Thus, a clinical isolate of HCMV directly inhibited the proliferation of myeloid BM progenitors in vitro wheras CB progenitors were not affected. This difference in the susceptibility of CB and BM cells to HCMV may partly be caused by the slow cycling rate of naive CB progenitors compared to BM progenitors at the time of infection.

Adult↗
PubMed1996

Intravascular lung macrophages play an essential role in lipid entrapment and the inflammatory tissue reaction seen after long-term lipid-based parenteral nutrition in pigs. An ultrastructural study.

To detect possible interactions between lipid-based total parenteral nutrition (TPN) substrates and mononuclear phagocytes, ultrastructural in vitro and in vivo studies were carried out on material from pigs. Mononuclear phagocytes isolated from peripheral blood, phagocytosed lipid after incubation with 1 mg/ml Intralipid for 24 h. Similarly, lipid was taken up by intravascular macrophages in the lungs and liver after central venous administration of TPN containing 2.3 g/kg body weight/day of Intralipid for 5-7 weeks. Lipid accumulation was almost exclusively found intravascularly in the lungs and liver, and not in macrophages obtained from bronchoalveolar lavage fluid. A morphometric study of the lung capillaries showed that the macrophages in TPN animals had increased in size and number, and occupied a larger portion of the capillary lumina. The macrophages appeared to be activated, but the endothelial lining was well preserved. Free intravascular lipid droplets had a diameter both in vitro and in vivo of about 0.5 micron, indicating good stability of the emulsion. We suggest that the lipid uptake stimulates the macrophages and thereby plays a role in the lung tissue inflammation seen in response to long-term lipid-based TPN in pigs.

Animals↗
PubMed1995

[Revolution in diagnostic microbiology. Needs, driving forces and consequences].

Introducing molecular biological technology into medical microbiology promotes deeper insight into the epidemiology, pathogenesis, diagnostics and treatment of infectious diseases. New technology has helped to highlight the complicated biological interaction between host and microbes and has created a need for more advanced technology both in microbiological diagnostics and in microbiological science. Extra-professional factors like the high prestige of new techniques have also been of considerable significance. Medical microbiologists will become an important link between the inventors of new technology and the physicians who diagnose and treat the patients. Through these contacts and their diagnostic laboratory work, they will become important generators and communicators of knowledge. In this connection it will be important to represent reason in introducing technology in medical microbiological diagnostics. Since patients are expected to play a more active part in health care, communicating knowledge to patients and the population in general will become an obligation.

Genetic Techniques↗
PubMed1995

Long-term lipid-based total parenteral nutrition activates mononuclear cells and modulates membrane lipid composition in pigs.

In previous studies we have found lung granulomas in pigs on long-term soybean-based total parenteral nutrition (TPN). In the present study we have investigated activities and membrane lipids of cells known to participate in a granulomatous process. Pigs were given TPN with soybean emulsion for 7 weeks, controls were given saline intravenously and consumed a similar caloric load in a standard oral diet. Spontaneous nitroblue tetrazolium (NBT) reduction increased 204% in peripheral blood mononuclear cells (MNC) from TPN animals compared to controls (p < 0.05), and 161% (p = 0.05) in alveolar macrophages. The spontaneous lymphocyte mitogen response (LMR) rate in MNC increased 299% (p < 0.05). Endotoxin-stimulated procoagulant activity in MNC tended to increase in TPN animals. Acid phosphatase and lysozyme production in alveolar macrophages were not significantly changed. The serum neopterin level at the end of the observation was 7.0 nmol l-1 in TPN animals compared to 3.9 nmol l-1 in controls (p < 0.01), while interleukin-1 and tumour necrosis factor were not detectable. These findings indicated in vivo activation of peripheral blood monocytes, lymphocytes and alveolar macrophages in pigs on TPN. The membrane lipid contents of linoleic acid (18:2, n-6) increased, while arachidonic acid (20:4, n-6) tended to decrease both in MNC and lung tissue. Thus, linoleic acid conversion did not lead to accumulation of arachidonate in the cell membranes. Direct effects on monocytes, lymphocytes and alveolar macrophages of TPN particles, and altered cell membrane function, due to linoleic acid enrichment, are tentative explanations for the raised cell responses. Such cell activation may have contributed to the formation of granulomas.

Acid Phosphatase↗
PubMed1994

Expression of protein kinase A and protein kinase C during ongoing human cytomegalovirus infection.

During an HCMV infection, transcription of viral and cellular genes are mutually regulated. Several cellular proteins have been implicated in the regulation of the HCMV major immediate early promoter (MIEP) which have been shown to respond to cAMP as well as activation of protein kinase C (PKC). We have examined the effect of an ongoing HCMV infection at the mRNA level for the catalytic and regulatory subunits of protein kinase A (PKA) and alpha and beta isoforms of PKC. There was a moderate elevation for PKA C alpha and RI alpha at immediate early times (0.5-2 h) after HCMV infection. Later in the infection cycle (24-72 h), mRNA level for PKA regulatory subunit RI alpha and PKC alpha were decreased compared with control cells. Messenger RNA levels for the PKA RII alpha and RII beta as well as PKC beta were not affected by HCMV infection. During the infection cycle the PKA subunits and PKC isoforms appeared to be independently regulated. It was also evident that the basal mRNA levels of PKA subunits and the PKC isoforms were sufficient for the PKA and PKC activity required during an HCMV infection in permissive fibroblast cells.

Cell Line↗
PubMed1994

Rapid detection of cytomegalovirus infection in immunocompromised patients.

Several routinely employed diagnostic methods were analysed for their usefulness in aiding an early and rapid diagnosis of human cytomegalo-virus infection in immunocompromised patients. Clinical samples obtained during an 18-month period were examined by conventional culture, the shell vial method, detection of pp65 antigen and the polymerase chain reaction. Detection of pp65 antigen in peripheral leukocytes was the most useful method for rapid detection of infection at an early stage. Results of other rapid detection methods, the shell vial method and the polymerase chain reaction, gave useful support, while results obtained by conventional culture were not available until after the initiation of therapy. Only a small proportion of serological tests provided useful information for determining whether to treat the patient.

Antigens, Viral↗