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G Reibnegger

Publications and source records attributed to G Reibnegger.

At least 127 records · Page 7Linked to original sources
PubMed1990

Urinary neopterin excretion in patients with uterine sarcomas.

Neopterin, a pyrazinopyrimidine compound, is a marker of activation of cell-mediated immunity. Urinary neopterin concentrations were measured in a total of 44 patients with uterine sarcomas. Pretherapeutic neopterin excretions were elevated in 78% (14/18). The mean neopterin concentration of patients with sarcomas was significantly higher (P less than 0.0001) than that obtained in women with benign myomas and healthy controls. Furthermore, a significant correlation of normal or raised neopterin concentrations with the clinical course of disease was found. These data suggest that urinary neopterin measurement might be a useful immunologic marker for women with uterine sarcomas.

Adolescent↗
PubMed1990

Comparison of serum and urine neopterin concentrations in patients with HIV-1 infection.

Urine and serum neopterin concentrations are now widely used to monitor patients with HIV-1 infection. However, there are no published studies comparing the levels in urine and serum, and relating both to the patients' immune status. Urine and serum neopterin concentrations correlated closely in our study population of 37 HIV-1 seropositive patients (34 homosexuals, 3 drug addicts) and 10 HIV-1 seronegative homosexuals. Our data further show that urine and serum neopterin concentrations correlate almost identically with the clinical and immunological presentation of HIV-1 infected individuals, as expressed by the Walter Reed Staging classification. In addition, there was no difference between the correlation of neopterin concentrations in either serum or urine with the Quetelet indices. It will depend on the clinical situation whether blood or urine sampling is preferred. Collection and handling of urine samples from HIV infected patients is less risky to health care personnel in HIV settings.

Adult↗
PubMed1990

Tetrahydrobiopterin biosynthetic activities in human macrophages, fibroblasts, THP-1, and T 24 cells. GTP-cyclohydrolase I is stimulated by interferon-gamma, and 6-pyruvoyl tetrahydropterin synthase and sepiapterin reductase are constitutively present.

Interferon-gamma induces tetrahydrobiopterin biosynthesis in human cells and cell lines. Macrophages are peculiar in the formation of large amounts of neopterin derivatives as compared to tetrahydrobiopterin (Werner, E. R., Werner-Felmayer, G., Fuchs, D., Hausen, A., Reibnegger, G., and Wachter, H. (1989) Biochem J. 262, 861-866). Here we compare the impact of interferon-gamma treatment on activities of GTP-cyclohydrolase I (EC 3.5.4.16), 6-pyruvoyl tetrahydropterin synthase, and sepiapterin reductase (EC 1.1.1.153) in human peripheral blood-derived macrophages, normal dermal fibroblasts, THP-1 myelomonocytic cells, and the T 24 bladder transitional-cell carcinoma line. Upon interferon-gamma treatment, GTP-cyclohydrolase I activity is increased 7- to 40-fold, whereas 6-pyruvoyl tetrahydropterin synthase and sepiapterin reductase activities, which are constitutively present in all four investigated cells, remain unchanged. In fibroblasts and T 24 cells GTP cyclohydrolase I activity is the rate-limiting step of tetrahydrobiopterin biosynthesis. In macrophages and in THP-1 cells, however, the induced GTP cyclohydrolase I activity is higher than the 6-pyruvoyl tetrahydropterin synthase activity, leading to the accumulation of neopterin and neopterin phosphates.

Alcohol Oxidoreductases↗
PubMed1990

Value of urinary neopterin in the differential diagnosis of bacterial and viral infections.

Neopterin is released by stimulated macrophages. In this study we analyzed the diagnostic potential of urinary neopterin concentrations in patients with bacterial and viral infection. All but one of 17 patients with viral infection had increased urinary neopterin concentrations. Patients with bacterial urinary tract infection also showed increased neopterin concentrations, whereas patients with bacterial pneumonia had significantly lower neopterin levels. In addition, patients with acute bacterial pneumonia had lower neopterin levels than patients with protracted infection. A significant inverse correlation between urinary neopterin and hemoglobin concentrations was found. Neopterin concentrations could serve as a helpful additional marker of infectious diseases. Combined with other clinical and laboratory parameters it is a useful parameter for distinguishing between viral and bacterial origins of infection, as was shown by multivariate stepwise linear discriminant analysis.

Adult↗
PubMed1990

Urinary neopterin concentrations and T-cell subset data in HIV-1 infection.

We investigated the ability of urinary neopterin concentrations and T-cell subset data, and their ratios to discriminate between anti-HIV-1 seronegatives, seropositives, and AIDS cases. Using receiver-operated-characteristics curves, neopterin levels were shown to provide the best discrimination. Of the ratios derived from the single variables, neopterin per CD4+ cell counts and neopterin per CD4+/CD8+ cell ratio were superior to the CD4+/CD8+ cell ratio. Multivariate analyses were performed using a generalized likelihood ratio approach as well as linear discriminant analysis. The combination of neopterin concentration and CD4+ T-cell count is well suited to discriminate between various stages of HIV-1 infection and, therefore, we recommend using more than one assay to evaluate disease progression.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Immune activation markers to predict AIDS and survival in HIV-1 seropositives.

Neopterin concentrations in body fluids of HIV-1 seropositives provide predictive information. In 1986, we examined serum and urine neopterin concentrations in 29 HIV-1 seropositives. Serum levels of soluble IL-2 receptor (sIL2R), soluble CD8 (sCD8), tumour necrosis factor alpha (TNF-alpha) and circulating immune complexes (CIC) were retrospectively analysed in 1989. All individuals had increased serum and urine neopterin, sIL2R and CIC concentrations, 27/29 had increased sCD8 concentrations, whereas all had normal TNF-alpha levels. During a 3-year follow-up, high urine and serum neopterin concentrations were significantly associated with progression to AIDS and with the occurrence of AIDS-associated death. Both neopterin variables were of similar predictive value (p less than 0.001, generalized Wilcoxon test). sIL2R concentrations were of borderline significance in predicting the onset of AIDS (p = 0.05). All other parameters lacked predictive information in our study. We conclude, that chronic immune activation is detectable in almost all HIV-1 seropositives. Chronic immune activation may be associated with HIV-1 replication and may contribute to the immunopathology of HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Immune activation and decreased tryptophan in patients with HIV-1 infection.

We compared tryptophan, neopterin, and interferon-gamma (IFN-gamma) concentrations in serum and cerebrospinal fluid (CSF) of 22 patients with human immunodeficiency virus type 1 (HIV-1) infection. Tryptophan levels were found to be decreased in CSF and serum of patients whereas neopterin levels in CSF and serum and serum IFN-gamma concentrations were increased compared to healthy HIV-1 seronegatives. Tryptophan concentrations correlated negatively to neopterin concentrations, and serum neopterin concentrations correlated positively to IFN-gamma concentrations. Thus, decrease of tryptophan levels is associated with chronic immune stimulation in patients with HIV-1 infection. From the data it appears that reduced tryptophan in patients may result from induction of indoleamine (2,3)-dioxygenase by IFN-gamma.

Adult↗
PubMed1990

Urinary excretion of porphyrins is increased in patients with HIV-1 infection.

Urine concentrations of total porphyrins and of porphyrin precursors, delta-aminolaevulinic acid and porphobilinogen, were analysed in the first-morning urine samples of 36 people with established HIV-1 infection. For comparison, we also analysed the urine samples of 26 healthy HIV-seronegative people. In patients with HIV-1 infection concentrations of total porphyrins were found to be significantly higher than in healthy controls. Furthermore, there was a close correlation between concentrations of total porphyrins and porphobilinogen and urine neopterin concentrations in patients. Our data indicate an association between chronic immune activation and altered porphyrin metabolism. The data may provide a rationale for the observation of acute porphyria in patients with HIV-1 infection.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Increased serum neopterin in patients with HIV-1 infection is correlated with reduced in vitro interleukin-2 production.

Recently we have observed that the CD4+ T cell response of peripheral blood mononuclear cells (PBMC) to soluble antigens is the first to be lost in the course of HIV-1 infection followed by the loss of response to HLA alloantigens. In this study we compared serum neopterin concentrations of individuals with early stages of HIV-1 infection (stages WR1 and WR2, Walter Reed staging system) with in vitro interleukin-2 (IL-2) production of PBMC in response to stimulation with soluble antigens (influenza A virus and tetanus toxoid) and alloantigens. Neopterin concentrations were significantly higher in HIV-1-seropositive individuals who showed deficient IL-2 production in response to recall antigens only or to all of the stimuli tested in vitro, compared with HIV-1-seropositive individuals who exhibited no CD4+ T cell defects. No difference in serum neopterin concentrations was observed between the group that was functionally deficient to soluble antigens only versus those who were unresponsive to both types of stimuli. It appears that the selective loss of the MHC self-restricted CD4+ T cell function is associated with an increase in serum neopterin levels. Neopterin concentrations are an estimate of the activation status of macrophages. We conclude that defective in vitro production of lymphokines by T lymphocytes is associated with activated macrophages in vivo.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Correlation between neopterin, interferon-gamma and haemoglobin in patients with haematological disorders.

In this study, we further investigated a possible link between activation of cell-mediated immunity and anaemia in patients with haematological neoplasias. We compared serum concentrations of interferon-gamma and neopterin with haemoglobin levels. Significantly increased interferon-gamma and neopterin concentrations indicated persistent activation of cell-mediated immunity. Neopterin levels correlated significantly to interferon-gamma concentrations and inversely to haemoglobin levels. The data indicate an association between activated macrophages and the development of anaemia in patients with haematological neoplasias.

Adult↗
PubMed1990

Decreased serum tryptophan in patients with HIV-1 infection correlates with increased serum neopterin and with neurologic/psychiatric symptoms.

We investigated serum neopterin, tryptophan, and kynurenine concentrations in 23 HIV-1 seropositive patients (Walter Reed Stage 4-6). Ten patients presented with polyneuropathy and three with dementia, one of the patients with dementia also had polyneuropathy and dementia. We found significant associations between lower trytophan concentrations and neurologic/psychiatric symptoms. The negative correlation of tryptophan with kynurenine and neopterin concentrations indicates activity of indoleamine 2,3-dioxygenase (IDO) in patients. IDO can be induced by cytokines such as interferon-gamma and therefore low tryptophan levels may result from chronic immune stimulation in HIV-1 seropositives.

Acquired Immunodeficiency Syndrome↗