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Biomedical subjects

J Justesen

Publications and source records attributed to J Justesen.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Current therapeutic targeting possibilities in leukemia].

Investigations on the configuration of immunoglobulin (Ig) and T-cell receptor (TCR) genes have become more and more widespread. Through these methods it is possible to identify malignant clones, which by a transforming event have been blocked in further differentiation but continued to proliferate. Such clonal expansions can be verified by the Southern Blotting procedure as differences in molecular weight between normal and rearranged DNA fragments. In the lymphatic disorders it is possible to assign the malignant clone to B cell lineage by rearrangement in the immunoglobulin light chain gene, while heavy chain and T-cell receptor genes do not show consistency in lineage restriction. In a study on AML patients with solitary expression of the T-cell marker CD7 we have identified a similarity in TCR beta and delta gene configurations, indicating a correlation between etiology and genetic pattern. Such observations can contribute to an elucidation of the malignant blood-diseases and by that a better choice in therapy.

Antigens, Differentiation↗
PubMed1989

Search for a retrovirus in long-term cultured cerebrospinal fluid cells and peripheral blood mononuclear cells from patients with multiple sclerosis.

Long-term peripheral blood mononuclear cell (MNC) cultures stimulated with interleukin 2 (IL-2) or IL-2 + phytohemagglutinin were established from 33 multiple sclerosis (MS) patients, 9 with other neurological diseases (OND), and 24 normal controls (C). Cultures were analysed for growth characteristics, reverse transcriptase (RT) in the culture medium, 2'-5' oligoadenylate synthetase in the cells, and cell morphology. None of these parameters differed in the MS group compared with the OND and C groups. Furthermore, 11 cerebrospinal fluid cell cultures were established without feeder cells. Morphology studies of the cells and RT assays of the supernatants from these cultures were normal. Induction studies by dexamethasone and 2-bromo-5'-deoxyuridine in 2 of these cultures did not reveal any signs of a virus. The significance of these results for the retrovirus hypothesis is discussed.

Adult↗
PubMed1989

Immunological recovery and dose evaluation in IFN-alpha treatment of hairy cell leukemia: analysis of leukocyte differentiation antigens, NK and 2',5'-oligoadenylate synthetase activity.

A low-dose interferon (IFN)-alpha regimen for the treatment of hairy cell leukemia (HCL) was evaluated by following changes in leukocyte differentiation antigens (LDA), natural killer cell (NK) and 2',5'-oligoadenylate (2-5A) synthetase activities. Due to hairy cells' (HC) weak expression of several antigens positive for T cells, B cells, NK cells and monocytes, the use of a double marker specific for hairy cells was needed to distinguish the different subpopulations. Analysis of LDA in peripheral blood (PB) showed a total normalization of the T cell and monocyte numbers within 90 days, the number of NK cells normalized in 90 to 180 d, whereas normalization of B cell number was seen only after 180 to 360 d of treatment. Mean pretreatment 2-5A synthetase activity was normal or low, but upon treatment the levels rose immediately to higher than normal values and remained high throughout the study. Pretreatment NK activity was low, but normalized after between 90 to 360 d, except in 2 patients with severe splenomegaly. In vitro incubation of peripheral blood mononuclear cells (PBMNC) with IFN-alpha induced activation of the NK and 2-5A synthetase activity in untreated patients, but with treatment these effects were gradually abolished, indicating an increasing effect of IFN-alpha in vivo with time. These results shows that the different PBMNC subpopulations and important immunological functions normalize with treatment. This normalization is, however, not seen until at least after 1 year of treatment, indicating that the treatment schedule should be longer. As no exhaustion to the effect of IFN was seen, as measured by the 2-5A synthetase activity, a continuing beneficial effect of treatment is anticipated. The increasing effect of IFN-alpha after the first signs of clinical effect suggests that the doses used in the present study were higher than necessary.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

IFN-induced modulation of histocompatibility antigens on human cells. Background, mechanisms and perspectives.

IFN proteins are a family of lymphokines with anti-viral effects. Several other effects of IFNs have also been described, including enhancement of natural killer (NK) cell activity, enhancement of cytotoxic T-lymphocyte activity, and enhancement of the expression of major histocompatibility complex (MHC) antigens. The latter effects have been characterized as immunomodulatory, whereas the well-known inhibition of growth of malignant cells has been termed anti-proliferative. This review summarizes the current knowledge of the enhancement of MHC products by IFNs. Whereas the basic methodologies for demonstrating the enhancement are simple and reliable, especially when using flow cytometry (FCM), the biological relevance of this reaction is largely unknown. Based on recent findings, however, we have hypothesized that the above-mentioned diverse effects of IFNs are all - in some way or other - related to the classical anti-viral mechanism. This concept proposes that the MHC-enhancing effect of IFNs is a vital part of the immunological defense against virus infections and an integral part of the anti-viral effects of IFN proteins.

Antiviral Agents↗
PubMed1987

Major proteins induced and down-regulated by interferons in human cultured cells: identification of a unique set of proteins induced by interferon-alpha in epithelial, fibroblast, and lymphoid cells.

In all, 40 major polypeptides ranging in molecular weights from 14.5 to 83 kDa were shown to be induced by IFNs alpha (also by IFN-alpha 2b and beta in a few cases) and gamma in human cultured cells of epithelial (transformed amnion cells (AMA)), fibroblast (proliferating and quiescent MRC-5 fibroblasts), and lymphoid origin (Molt-4). With the exception of a heat shock protein (IEF14 or hs x 70) and two tropomyosins (IEFs 52x and 55), none of these proteins corresponded to polypeptides (proliferation-sensitive or others) previously identified and catalogued by us. IFN-alpha induced the highest number of polypeptides in lymphoid cells, while the response to IFN-gamma was more pronounced in cultured epithelial and fibroblast cells. Several of the polypeptides induced by IFNs alpha and gamma were synthesized (albeit at different rates) by the control untreated cells, and in some cell types such as normal human peripheral blood mononuclear cells many were expressed at high levels. Only IFN-alpha-induced a unique set of proteins (alpha 1, 51 kDa; alpha 2, 15 kDa; alpha 19, 78 kDa; and gamma 10, 83 kDa) in all cultured cell types studied, implying that response to this IFN involves a shared biochemical pathway(s). Both IFN-alpha (also IFN-alpha 2b) and beta induced an identical group of proteins in AMA cells in agreement with the fact that type I IFNs share common receptors. IFNs alpha and gamma induced a few common polypeptides, but only gamma 10 (83 kDa) showed increased synthesis in all cell types exposed to either of these IFNs. A total of 28 major cellular polypeptides were down-regulated by IFNs in the various cell type studied. Different sets of proteins were affected, however, in each system, emphasizing the complexity of the mechanisms underlying the action of these factors. Treatment of synchronized G1 AMA cells with IFNs alpha, beta, or gamma (500 IU/ml, final concentration) did not inhibit their progression from G1 to S-phase as determined by indirect immunofluorescence using PCNA autoantibodies specific for cyclin. These observations were in line with the fact that IFNs did not affect dividin or cyclin(PCNA) synthesis (S-phase specific proteins) at least within the first 17 hr after their addition.

Amnion↗
PubMed1986

The physiology of stringent factor (ATP:GTP 3'-diphosphotransferase) in Escherichia coli.

The enzyme ATP:GTP 3'-diphosphotransferase catalyzes the transfer of the beta, gamma-pyrophosphate of ATP to the 3' position of GTP or GDP. The amounts of enzyme were measured in cell extracts of a relA+ strain of E. coli grown at different growth rates between 0.4 and 1.9 generations per hour, using precipitation with specific antibodies to purify the enzyme. The amount of enzyme was found to be a constant fraction of total protein at all growth rates corresponding to about 45 molecules of enzyme per genome equivalent of DNA. The purified enzyme has little catalytic activity by itself but has to be activated either by a complex of 70S ribosomes, mRNA and uncharged tRNA or by a solvent like ethanol at a concentration of about 20%. The kinetic constants of the enzyme for the transfer pyrophosphate from ATP to GTP in the ribosome-activated state were determined. The Vmax was estimated to be 140 mumol/min X mg at 37 degrees C and the S0.5 values for GTP and ATP were 0.35 and 0.53 mM, respectively. The reaction was estimated to have an equilibrium constant of about 300. In the pyrophosphate transfer from ATP to GDP the Vmax was estimated to be 90 mumol/min X mg at 37 degrees C and the S0.5 for GDP as 0.3 mM. During amino acid starvation of a relA+ strain of E. coli the amounts of enzyme and the catalytic capacity of the enzyme are sufficient to maintain the observed ppGpp levels in the cells at all growth rates.

Adenosine Triphosphate↗
PubMed1986

Synergistic effects of HuIFN-gamma on 2',5'-oligoadenylate synthetase induction by HuIFN-alpha.

Human skin fibroblast cells were treated with three types of human interferon (HuIFN), alpha, beta, and gamma separately, and in series of combinations at different concentrations. The IFN-induced enzyme, 2',5'-oligoadenylate (2-5A) synthetase, which is thought to be mediating the major part of the antiviral activity, was measured subsequent to 24 h treatment. The HuIFN-gamma potentiated the induction of 2-5A synthetase elicited by either HuIFN-alpha or HuIFN-beta, but the effect was seen only at low levels, i.e., 1-10 units. At higher levels, an antagonistic effect was seen. The individual subspecies of the HuIFN-alpha from native HuIFN-alpha were purified, separated, and analyzed for their ability to induce antiviral activity in human and bovine cells together with their capacity to induce 2-5A synthetase. Of the 12 species with molecular weights between 16,950 and 22,900 daltons, one species (MW 21,800) exerted peculiar properties in that it protected human cells better than bovine--at the same IFN level--and, it induced more 2-5A synthetase in human cells than in bovine cells.

2',5'-Oligoadenylate Synthetase↗
PubMed1986

Genetically determined difference in the antiviral action of alpha/beta interferon in cells from mice resistant or susceptible to herpes simplex virus type 2.

Resistance of mice to infection with herpes simplex virus type 2 (HSV-2) is genetically determined. Embryonic cells from susceptible BALB/c and resistant C57BL/6 mice were equally sensitive to infection with HSV-2 as judged by plaque area, plaquing efficiency, endpoint titration and virus yield. Cells from C57BL/6 mice showed a higher sensitivity than cells from BALB/c mice to the protective action of two preparations of alpha/beta interferon against challenge with HSV-2. This was evident both from c.p.e. inhibition and yield reduction experiments. The difference in sensitivity was dependent on virus dose and was greatest (up to 50-fold) with low virus doses. An analysis of the genetics of the alpha/beta interferon sensitivity in cells from embryos of parental mice and embryos derived from reciprocal matings between HSV-2-resistant and -susceptible mice suggested that interferon sensitivity is inherited as a co-dominant autosomal trait. The induction of the interferon-induced enzyme 2'-5'-oligoadenylate synthetase was also different in cells from the two mouse strains, since significant levels were only detected in cells from C57BL/6 mice. It is suggested that differential interferon sensitivity of cells from HSV-2-resistant and -susceptible mice might be a factor of importance for the course of the infection.

2',5'-Oligoadenylate Synthetase↗
PubMed1986

Interferon induction, 2'-5' oligo A synthetase and lymphocyte subpopulations in out-patients with multiple sclerosis in a longitudinal study.

Nine patients with multiple sclerosis, four with relapsing-remitting disease, and five with chronic progressive disease, together with eight healthy control, were followed for nearly a year with monthly clinical and laboratory examinations. Alpha- and gamma-interferon was induced in lymphocytes with different viruses and PHA, no differences were found between healthy controls and multiple sclerosis patients. The alpha- and gamma-interferon induced enzyme 2'-5' oligo A synthetase in lymphocytes was found to have a tendency to be lower in multiple sclerosis patients than in healthy controls. When medians of ratios of helper/suppressor blood lymphocytes in multiple sclerosis patients were compared with healthy controls, the same results were found, although higher values of ratios were found among the patients and the highest value was found in a patient with chronic progressive disease. No correlation to disease activity could be found in interferon inductions, 2'-5' oligo A synthetase concentrations and ratios of OKT4/OKT8. In particular no change in ratio was found in relation to five exacerbations taking place in the four multiple sclerosis patients with acute relapses.

2',5'-Oligoadenylate Synthetase↗
PubMed1985

The interferon-induced enzyme 2-5A synthetase adenylates tRNA.

The interferon-induced enzyme 2-5A synthetase is shown to adenylate tRNA. Yeast tRNAPhe was incubated with the enzyme in the presence of double stranded RNA (in this case polyI-polyC) and ATP or deoxyATP. The reaction products were analyzed by ribonuclease T1 digestion of the tRNA, polyacrylamide gel electrophoresis and autoradiography. Using ATP, the 2-5A synthetase adds one, two or three AMP residues to the 3'-end of the tRNA whereas when dATP is replacing ATP, only one nucleotide unit is added. It is concluded that one of the mechanisms of the interferon-induced antiviral effect may be an inhibition of the translation process caused by an inactivation of tRNA molecules by a 2-5A synthetase catalyzed 2'-adenylation of the 3'-end.

2',5'-Oligoadenylate Synthetase↗
PubMed1984

(2'-5') Oligoadenylate synthetase in the maturation of rabbit reticulocytes.

The (2'-5') oligoadenylate synthetase normally found in interferon-treated cells has also been detected in considerable amounts in normal rabbit reticulocytes not exposed to interferon. The activity of this enzyme has been followed during the development of the reticulocytes to erythrocytes. A high level was found just after the formation of reticulocytes and this activity decayed with a half-life of about 3 days. In lymphocytes the (2'-5') oligoadenylate synthetase was found to stay at a constant level, which indicates the absence of interferon in the plasma.

2',5'-Oligoadenylate Synthetase↗
PubMed1982

Structural requirements of (2'-5') oligoadenylate for protein synthesis inhibition in human fibroblasts.

The structural requirements of (2'-5')-oligoadenylic acid (pppA(2'p5'A)x, X greater than or equal to 1 or (2'-5'An) for inhibition of protein synthesis in cells were examined with a modified calcium-coprecipitation technique, using a series of trinucleotide analogs (pppA2'p5'A2'p5'N, N=rC, rG, rU, T, dC, dG, dA). In this system both the degree and the duration of the inhibition of protein synthesis were dependent on the added concentration of (2'-5')A3. Of all the heterotrimers, only the deoxy A derivative was active as an inhibitor of protein synthesis, while the other members of the analog series were found to have no inhibitory effects. In competition experiments between (2'-5')A3 and the non-active analogs, three heterotrimers were shown to reduce the activity of (2'-5')A3 in protein inhibition. In contrast, the dephosphorylated (2'-5')A3 had no inhibitory effect and was not effective in blocking (2'-5')A3. These results indicate that the 5'-terminal triphosphate is important for binding of (2'-5')A3 to the site of (2'-5')An action and the adenine base at the 2'-terminus is important for activating the machinery responsible for protein synthesis inhibition in the cells, most likely the (2'-5')An-activated nuclease.

Adenine Nucleotides↗
PubMed1982

Inhibition of mouse fibroblast interferon by gangliosides. Differential effects on biological activity and on induction of (2'--5')oligoadenylate synthetase.

Gangliosides are potent inhibitors of the antiviral activity of mouse fibroblasts and other beta-interferons. We have compared the effects of gangliosides on antiviral and antigrowth activities of mouse fibroblast interferon and on the induction of (2'--5')oligoadenylate synthetase, one of the enzymes implicated in the antiviral state induced by interferon. Whereas both biological effects appear to be inhibited by gangliosides in an analogous fashion, inhibition of induction of (2'--5')oligoadenylate synthetase does not correlate with inhibition of vesicular stomatitis virus replication. Ganglioside concentrations that inhibit the interferon-induced (2'--5')oligoadenylate synthetase to levels close to those of uninduced cells, still allow for a 100--1000-fold reduction of viral yield. Significantly higher ganglioside concentrations are required to prevent completely the antiviral effect. This biphasic relationship between (2'--5')oligoadenylate synthetase levels and inhibition of viral yield suggests that no or very small increases in synthetase levels are involved in inhibition of virus by between two and three orders of magnitude.

2',5'-Oligoadenylate Synthetase↗