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Biomedical subjects

G Reibnegger

Publications and source records attributed to G Reibnegger.

At least 181 records · Page 10Linked to original sources
PubMed1988

Approach to define "normal aging" in man. Immune function, serum lipids, lipoproteins and neopterin levels.

In 53 healthy women with mean age 25.1 years (age range 21-34 years) and in 51 healthy women with mean age 82.1 years (age range 75-91 years), a panel of immunological and biochemical tests was performed. These tests, comprising lymphocyte mitogen responsiveness, phenotyping of lymphocytes, uptake of low density lipoprotein by T cells, serum levels of neopterin, lipids and lipoproteins, as well as routine blood chemistry, were investigated for a possible effect of age and of the classification according to the SENIEUR Protocol of admission criteria by the European Economic Community's Concerted Action Program on Aging (EURAGE). A highly significant effect of age on serum levels of neopterin, lipids and lipoproteins was found. No clear effects, however, of SENIEUR status on these variables was detected. As expected, age had a significant impact on mitogen responsiveness of T cells. Proportional numbers of helper/inducer and cytotoxic/suppressor T cells (as well as antigen density on these cells) were not influenced by age. SENIEUR classification did not affect these immunologic variables. Thus, most of the tested variables that are not included in the SENIEUR admission criteria appear to present information not yet covered by the SENIEUR variables. Various ways for a possible revision or extension of the SENIEUR Protocol are discussed.

Adult↗
PubMed1988

Selective induction of mononuclear phagocytes to produce neopterin by interferons.

Interferon-gamma (IFN-gamma) has been shown to be a potent inducer of neopterin secretion by human peripheral blood monocytes/macrophages (1). In this paper, it is shown that other known stimuli of monocytes (e.g., to secrete proteases or to migrate) such as zymosan-activated human serum, lipopolysaccharide, human C3/iC3 and zymosan coated with complement were unable to trigger monocytes/macrophages to release neopterin. Monocytes/macrophages could be stimulated solely by IFN-gamma (25 U/ml) and IFN-alpha at very high concentrations (10,000 U/ml). In the case of human peripheral blood mononuclear cells (PBMNC), basically the same pattern was observed. If however, in the buffer controls PBMNC showed some neopterin release, all stimuli triggered an increase of neopterin secretion: 10,000 U/ml IFN-alpha induced the same amount of secreted neopterin as did 25 U/ml of IFN-gamma. Both caused higher levels of neopterin secretion than ZAS, LPS and C3/iC3. Amongst the supernatants from PBMNC, only those which were obtained from cells activated with IFN-gamma or -alpha stimulated monocytes/macrophages to produce neopterin. Supernatants from lymphocytes activated with zymosan, lipopolysaccharide and interferon did not contain neopterin, nor did the latter induce monocytes/macrophages to generate and secrete neopterin. Antibodies against IFN-gamma inhibited the triggering effect of the supernatants except when generated by IFN-alpha at 10,000 U/ml. These results demonstrate that both interferons, IFN-gamma and IFN-alpha, the latter only at a 400-fold higher concentration, can trigger monocytes/macrophages directly to secrete neopterin. ZAS, LPS and C3/iC3 are weakly effective only on a mixture of lymphocytes and monocytes/macrophages, provided this cell mixture shows already a basic spontaneous neopterin release.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Urinary neopterin in infants with primary immunodeficiency.

Neopterin is produced in large amounts specifically from macrophages upon stimulation with interferon-gamma (IFN-gamma). Measurement of neopterin allows a direct in vivo quantification of T cell activation. This is particularly useful, e.g., in early diagnosis of graft rejection. Since disease states with elevated neopterin levels in some cases are coupled with an impaired cellular immunity, we decided to investigate the possible influence that severely diminished cellular immunity might have on urinary neopterin levels. Our investigation on six children with severe primary immunodeficiency presents some evidence that immunodeficiency itself does not account for an increase in neopterin when patients are free from infections. Neopterin was also normal in an SCID patient who was completely lacking T cells and was suffering from severe infections. Two patients with primary immunodeficiency and residual T lymphocytes suffered from severe infections and showed elevated neopterin. The data support the hypothesis that elevated neopterin levels are dependent on the presence of activated T lymphocytes. Residual T lymphocytes of SCID patients have the capacity to induce neopterin in vivo when patients suffer from infections.

Adenosine Deaminase↗
PubMed1988

Tryptophan degradation in patients infected by human immunodeficiency virus.

Tryptophan and kynurenine were measured retrospectively in sera of 11 male patients with advanced human immunodeficiency virus (HIV) infection (Walter Reed stages 4 and 6). Tryptophan levels are significantly reduced to less than 50% in patients with HIV infection and kynurenine levels significantly elevated when compared to sex and age matched controls. The decrease of tryptophan levels might contribute to neurologic symptoms often associated with HIV infection. Since interferon-gamma induces degradation of tryptophan via the kynurenine pathway, the present results may be consistent with enhanced endogenous production of interferon-gamma in advanced HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Neopterin levels in long-term hemodialysis.

We studied 20 patients on long-term hemodialysis. Concentrations of neopterin and creatinine were quantified in serum and in exchange buffers before, during and after treatment sessions. Neopterin is a low molecular weight product released by human macrophages upon stimulation with interferon gamma. It permits the quantification of the level of cellular immune activation in vivo. Neopterin and neopterin/creatinine ratios were found to be significantly increased in all patients. When comparing 15 patients treated with acetate exchange fluid buffers versus 5 patients treated with hydrogencarbonate, neopterin levels did not differ. Statistical computations revealed that the length of time on dialysis contributed to the increase of neopterin concentrations. Higher grade of cellular immune activation was preferentially detectable in those patients who had been on dialysis for more than 1 year. The demonstrated state of enhanced immune activation in dialysis patients might also help to explain accelerated development of AIDS in dialysis patients when infected with HIV.

Acetates↗
PubMed1988

Neopterin estimation compared with the ratio of T-cell subpopulations in persons infected with human immunodeficiency virus-1.

We measured neopterin, a biochemical indicator for the activation of cell-mediated immune reactions, in urines from 105 individuals at risk of infection with human immunodeficiency virus-1 (HIV-1), 83 of whom were seropositive for antibody to HIV-1. We compared absolute numbers of T-cell subsets (CD4+ helper/inducer T-cells, CD8+ suppressor/cytotoxic T-cells), and the ratio of CD4+ T-cells to CD8+ T-cells with the urinary neopterin concentrations. Concentrations of neopterin in urine were inversely correlated with absolute numbers of CD4+ T-cells and with CD4+/CD8+ ratios in anti-HIV-1 seropositive subjects but not in those seronegative. Various statistical comparisons of the data further demonstrated that neopterin concentrations showed larger differences between anti-HIV-1 seronegative and seropositive subjects than absolute numbers of CD4+ T-cells or CD4+/CD8+ ratios. These results seem to indicate that neopterin concentrations increase earlier in the course of HIV-1 infection, before effects on T-cell subpopulations are detectable, and may further support the suggestion that neopterin measurement could be of use for monitoring infected subjects or predicting the progression of disease.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Potential of urinary neopterin excretion in differentiating chronic non-A, non-B hepatitis from fatty liver.

Urinary neopterin excretion was measured in 26 patients with histologically proven chronic non-A, non-B hepatitis (16 chronic persistent hepatitis, 10 chronic active hepatitis) and in 16 patients with steatosis. The potential of neopterin levels to discriminate between the two patient groups was compared with that of standard laboratory variables. Neopterin levels and triglycerides were shown to be the best variables for discriminating between the hepatitis and fatty liver patients, neopterin being the more specific of the two. Neopterin excretion in chronic persistent hepatitis was not statistically different from that in chronic active hepatitis. In the absence of specific tests, increased neopterin excretion seems to be a useful marker for diagnosing chronic non-A, non-B hepatitis and particularly in differentiating it from fatty liver.

Adult↗
PubMed1987

Clinical significance of neopterin for prognosis and follow-up in ovarian cancer.

Neopterin, a pyrazinopyrimidine compound, is a marker of activation of cell-mediated immunity. The prognostic value of pretherapeutically and of serially measured urinary neopterin levels in patients with ovarian cancer was assessed, in a blinded manner, by analysis of 658 urine specimens from 74 women. The specimens were collected during a 5-year period (January 1981 to January 1986). Thirty-one deaths due to cancer were observed during the study period. By statistical analysis, a significant predictive value of pretherapeutic neopterin levels was found and compared with that of other possible prognostic clinical and laboratory findings. Multivariate analysis, using stratification by tumor stage, demonstrated that this predictive information was independent of other variables. A significant association was found between serial neopterin measurements and the current risk of death during follow-up (P less than 0.0001). In addition, current death risk was correlated with neopterin levels measured 6 months previously (P = 0.026). The histological outcome at surgical reexamination was correlated with the current neopterin levels (P = 0.016). Further, normal neopterin levels in women with evidence of tumor at surgical reexamination were shown to be a sign of better prognosis than elevated levels. Measurement of urinary neopterin levels during follow-up of women with ovarian cancer appears to be a valuable adjunct to conventional techniques, particularly in patients refusing explorative surgery.

Biopterins↗
PubMed1987

Neopterin as discriminating and prognostic parameter in healthy homosexuals, ARC and AIDS patients.

Urinary neopterin, a sensitive marker for activation of cell mediated immunity, is compared to clinical and laboratory data in 5 patients with AIDS, in 15 patients with ARC and in 40 male subjects without AIDS-related clinical signs attending an AIDS outpatient clinic. The sensitivity of neopterin for AIDS-related diseases was higher than that of the CD4+/CD8+ subset ratio. The differences in neopterin levels between the controls, ARC and AIDS patients were found to be more significant than the T-cell subset data. The observation that the 3 AIDS patients with the highest neopterin levels have died whereas the two others with the lower levels are still alive also underlines the prognostic potential of urinary neopterin level determinations. Measurement of urinary neopterin is thus recommended as an additional criterion for monitoring ARC and AIDS patients.

AIDS-Related Complex↗