Biomedical subjects

C Baumberger

Publications and source records attributed to C Baumberger.

12 recordsLinked to original sources

PubMed1996

Prognostic value of viremia in patients with long-standing human immunodeficiency virus infection. Swiss HIV Cohort Study Group.

Human immunodeficiency virus (HIV) viremia was evaluated in 73 patients with long-standing infection to investigate its relationship with clinical or biologic parameters and to assess its use as a predictor of clinical progression and death. After adjustment for other parameters, baseline HIV RNA level was significantly associated with baseline clinical stage and CD4 cell count. During follow-up (mean, 14.6 months), 16 patients died; 34 others had clinical progression of disease. In multivariate analysis, mortality was better predicted by baseline CD4 cell count (relative hazard [RH] for 100-cell decrease, 3.5; 95% confidence interval [CI], 1.5-8.2; P = .003) than by HIV RNA (P = .28) or clinical stage. HIV RNA level was the best predictor of clinical progression (RH for 1 log increase, 2.8; 95% CI, 1.6-4.9; P < .001). Monitoring of HIV RNA level may help to identify patients who might benefit from antiretroviral or prophylactic therapy.

Adult↗

PubMed1996

Combined therapy with zidovudine and L-697,661 in primary HIV infection.

OBJECTIVE: To decrease viraemia levels in primary HIV infection by using a combination of zidovudine (ZDV) and L-697,661. DESIGN: Four primary HIV-infected patients were treated for 6 months with ZDV, 250 mg twice daily, in association with the non-nucleoside reverse transcriptase inhibitor L-697,661 500 mg three times daily. Viraemia, proviral DNA, CD4 and CD8 cell counts were measured serially during 18 months. RESULTS: Viraemia decreased to undetectable levels (< 200 RNA copies/ml) in two patients. A third patient had a marked decrease followed by a rebound during therapy; viraemia levels did not vary markedly in the fourth patient. A rebound in viraemia levels was observed within 15 days of discontinuation of therapy in the three responding patients. Proviral levels evolved in parallel with viraemia but were always detectable in all patients. In the three patients with an initial decrease of viraemia, CD4 cell counts were within the normal range 2 months after initiation of therapy and did not markedly decrease after discontinuation of therapy. In the two patients with partial or no response of viraemia, mutations associated with low level of resistance to L-697,661 appeared during treatment. CONCLUSION: A marked decrease of viraemia can be achieved in some primary HIV-infected patients with combined therapy. Six months of treatment does not prevent a rebound of viraemia, which was observed within 15 days of interruption of therapy.

Adult↗

PubMed1995

Early and prolonged decrease of viremia in HIV-1-infected patients treated with didanosine.

Fourteen patients previously treated with zidovudine were monitored for laboratory parameters and clinical events during 1 year after introduction of didanosine (ddI) monotherapy. Proviral human immunodeficiency virus type 1 (HIV-1) copy numbers (cell-associated DNA) and concentration of free virions (viremia) were determined using a semiquantitative polymerase chain reaction (PCR). High levels of circulating virus were detected in all patients (range, 17 to 5,934 x 10(3)/ml of serum). Within 4 weeks of therapy, a decrease of viremia (60 to 98%) was observed in nine patients. After 1 year of treatment, eight of these nine patients still had decreased viremia when proviral HIV DNA was decreased or stable, and CD4+ lymphocytes were stable or higher in seven of these eight patients. Antiviral effect was more pronounced in the six patients with CD4+ > 100/mm3 at entry, five of them belonging to the subgroup of the seven responding patients as compared to two of eight patients with CD4+ < 100/mm3. Clinical events in this small group were not statistically correlated with virologic parameters; however, responding patients had a tendency to stabilize or gain weight. This study suggests that measurement of viremia deserves further study as a marker of antiviral efficacy and might predict, even at 4 weeks, the beneficial potential of ddI.

AIDS-Related Opportunistic Infections↗

PubMed1995

V3 sequences in primary HIV-1 infection.

OBJECTIVE: To determine HIV-1 genomic RNA and proviral DNA sequences of the third hypervariable region (V3 loop) of the envelope protein in patients with primary HIV-1 infection (PHI), and to compare these sequences with sequences from patients with more advanced HIV-1 infection. METHODS: Sera and peripheral blood mononuclear cells were collected from 24 patients with PHI living in Geneva. V3 sequences were determined using direct solid-phase sequencing on polymerase chain reaction (PCR) products. RESULTS: A 100% homology rate was observed between HIV-1 genomic RNA and proviral DNA paired nucleotide sequences from the V3 region in the 24 patients. Using a limiting dilution approach for three patients, a unique V3 sequence was observed for the genomic RNA. Three out of 24 amino-acid sequences presented the characteristic signature sequence QRGPGR, first described for the HIV-1LAI isolate, which is associated with lymphocytotropism. These three isolates also presented, for the V3 loop, a characteristic elevated charge (8) at physiological pH in comparison with the other isolates (3-5). There was no significant difference in the distribution of amino acids between the 24 V3 loop sequences from patients with PHI and 245 V3 loop sequences of the B subtype determined in patients with more advanced HIV-1 infection. CONCLUSION: The paired sequences recovered from HIV-1 genomic RNA and proviral DNA are identical for each of the 24 patients with PHI. Three isolates had the V3 loop characteristic signature sequence QRGPGR first described for the HIV-1LAI isolate. There is no characteristic V3 loop pattern associated with PHI isolates.

Adult↗

PubMed1995

Response of HIV RNA to didanosine as a predictive marker of survival.

OBJECTIVE: To evaluate whether early changes in viraemia in response to didanosine (ddI) predict death and occurrence of new AIDS-defining events. METHODS: Forty-three patients were followed during ddI treatment with sequential determinations of serum viraemia, mutations associated with drug resistance, CD4 counts and clinical evaluation. Patients were stratified into two groups of equal size, responders and nonresponders, using the median of individual changes in viraemia 1 month after initiation of ddI therapy. RESULTS: After 1 month of ddI, mean viraemia decreased by 0.35 log RNA copies/ml of serum (P < 0.001) in the population. A significant difference in survival (median, 14 and 35 months in nonresponders and responders, respectively; log rank, P = 0.004) and in the delay to the occurrence of new AIDS-defining events (median, 8 and 33 months in nonresponders and responders, respectively; log rank, P = 0.018) was observed. After stratification for presence of AIDS before starting ddI, viraemia response at 1 month remained predictive of both overall and AIDS-defining event-free survival (log rank, P = 0.0006 and P = 0.01). After a similar stratification for initial CD4, viraemia response still predicted overall survival (log rank, P = 0.009), but its predictive value for AIDS-defining event-free survival did not reach statistical significance (P = 0.12). High initial levels of HIV RNA, presence of mutation 215 or previous duration of zidovudine therapy were not predictive of survival. CONCLUSIONS: In patients treated with ddI, changes in viraemia at 1 month predict survival independently of initial AIDS diagnosis and initial CD4 counts.

Acquired Immunodeficiency Syndrome↗

PubMed1993

High levels of circulating RNA in patients with symptomatic HIV-1 infection.

OBJECTIVE: To evaluate the concentration of circulating RNA (viraemia) in patients with symptomatic primary HIV infection and relate it to sero-immunological parameters. METHODS: Semiquantitation of circulating HIV RNA and proviral HIV DNA was performed using the polymerase chain reaction. Circulating HIV RNA concentrations were expressed as virus equivalent (RNA copies/2) per ml serum. RESULTS: The mean CD4+ lymphocyte count for 19 patients with symptomatic primary HIV infection was 583 x 10(6)/l. Fifteen (79%) patients had detectable levels of p24 antigen (median 462 pg/ml). Circulating HIV RNA (median 2.3 x 10(7) virus equivalent/ml serum) and proviral HIV DNA (median 3630 copies/ml blood) were detected in all samples tested. Follow-up data for five patients (200-1600 days) showed a 1-3 log reduction in circulating RNA within 2 months. Later, circulating RNA concentrations were consistently greater than 10(3) virus equivalent/ml serum. Within 10 days no p24 antigen was detectable. Levels of CD4+ cells varied markedly from patient to patient during the follow-up and, in this small group, no evident correlation was observed between circulating RNA levels and CD4+ lymphocyte counts. CONCLUSIONS: High concentrations of circulating RNA (viraemia) were present in 19 patients with symptomatic primary HIV infection. Although a decrease in viraemia was observed during the following 2 months, viraemia persisted in all patients with long-term follow-up. This suggests that active viral replication is a continuous process in HIV-infected patients.

Adult↗

PubMed1993

Regulation of interleukin-1ra, interleukin-1 alpha, and interleukin-1 beta production by human alveolar macrophages with phorbol myristate acetate, lipopolysaccharide, and interleukin-4.

Human alveolar macrophages (AM) are antigen-presenting cells that have an important immune effector function in the lung. We have previously shown that AM produce a specific interleukin-1 (IL-1) inhibitor of 20 to 25 kD that blocks biologic activities of IL-1 alpha and IL-1 beta such as prostaglandin E2 production by fibroblasts. This inhibitor acts as a receptor antagonist (IL-1ra) by binding to the IL-1 receptor. We are now presenting evidence that the natural AM-derived IL-1ra is immunologically identical to IL-1ra cloned from human peripheral blood monocytes and shows a band at 20 kD compatible with the natural glycosylated IL-1ra. No constitutive expression of IL-1 mRNA was detected when analyzed by Northern blot immediately after bronchoalveolar lavage from six control patients. Comparison of in vitro kinetics of IL-1ra, IL-1 alpha, and IL-1 beta analyzed during culture in the presence or absence of phorbol myristate acetate revealed that their mRNA expression was asynchronous. IL-1 alpha and IL-1 beta mRNA were expressed after as little as 15 min, whereas IL-1ra mRNA was detectable only after 3 h in culture. The production of IL-1ra was measured by enzyme-linked immunosorbent assay and compared with that of IL-1 alpha and IL-1 beta. In freshly isolated AM (10(6)/ml), cell-associated IL-1ra was present in an average amount of 2.0 +/- 0.5 ng/ml, i.e., 25 and 100 times more than IL-1 alpha and IL-1 beta, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Western↗

PubMed1992

Suppression of metalloproteinase biosynthesis in human alveolar macrophages by interleukin-4.

To study the interaction of lymphocytes and macrophages in the control of extracellular matrix turnover, we determined the effects of several soluble T cell products on mononuclear phagocyte production of metalloproteinases. Cytokines including IL-2, IL-4, IL-6, tumor necrosis factor alpha (TNF alpha), GM-CSF, and IFN-gamma were each tested for capacity to modulate macrophage metalloproteinase and tissue inhibitor of metalloproteinases (TIMP) expression. The addition of IL-4 to cells cultured under basal conditions caused a dose-dependent suppression in the release of 92-kD type IV collagenase without affecting TIMP production. 92-kD enzyme secretion was inhibited by 50% with 1-2 ng/ml of IL-4 and by 90% with 10 ng/ml of IL-4. When cells were first exposed to killed Staphylococcus aureus to induce metalloproteinase production, IL-4 potently blocked the stimulated release of both interstitial collagenase and 92-kD type IV collagenase, again without effect upon TIMP. Metabolic labeling experiments and Northern hybridizations demonstrated that IL-4 exerted its action at a pretranslational level. Furthermore, IL-4 possessed the capacity to inhibit metalloproteinase expression even in the relatively immature peripheral blood monocyte. As reported previously (Shapiro, S. D., E. J. Campbell, D. K. Kobayashi, and H. G. Welgus. 1990. J. Clin. Invest. 86:1204), IFN-gamma suppressed constitutive macrophage production of 92-kD type IV collagenase. Despite the frequent antagonism observed between IL-4 and IFN-gamma in other systems, the combination of these two agents lowered metalloproteinase biosynthesis dramatically, whereas IL-4 opposed the IFN-gamma-stimulated production of cytokines (IL-1 and TNF alpha). IL-6 had only minimal effect upon metalloproteinase production, but appeared to specifically augment TIMP release. In summary, cytokines released by activated T cells may profoundly reduce the capacity of the macrophage to mediate extracellular matrix degradation.

Gene Expression↗

PubMed1991

Interleukin 1 receptor antagonist in human epidermis and cultured keratinocytes.

Interleukin 1 (IL-1), present in high amounts in normal human skin without any sign of inflammation, suggests a complex mechanism by which its bioactivity is regulated. The specific receptor antagonist of IL-1 (IL-1ra) was analyzed in human skin, sweat and cultured keratinocytes. Extracts of both skin and cultured keratinocytes blocked the binding of [125I]IL-1 to its receptor whereas sweat did not. The inhibitory activity was cell-associated, was not secreted by cultured keratinocytes, and IL-1ra mRNA was identified in these cells. There was an inverse relationship between the level of IL-1ra and that of IL-1 alpha and beta since extracts of differentiating keratinocytes (DK) and higher IL-1ra levels and expressed more mRNA for IL-1ra than non-differentiated keratinocytes (NDK), whereas NDK contained 4 times more IL-1 alpha and beta proteins than DK. This association of cell differentiation with a shift in agonist/antagonist ratio might be related to important autocrine or paracrine functions of IL-1 in normal and inflamed human skin.

Blotting, Northern↗

PubMed1991

Modulation of endotoxic activity of lipopolysaccharide by high-density lipoprotein.

Unlike agonists such as cytokines or hormones, the biological activity of bacterial lipopolysaccharide (LPS) is substantially modified by serum proteins. One such interaction in serum is with high-density lipoprotein (HDL) forming LPS-HDL complexes. LPS-HDL complexes have been previously shown to have reduced endotoxic activity, for example pyrogenicity, when compared to other forms of LPS in animal models. In this study, we report results of studies comparing the potency of LPS-HDL complexes with uncomplexed LPS as agonists for interleukin-1 (IL-1) production by two different sources of monocytes. LPS-HDL complexes were purified by ultracentrifugation in sodium bromide gradients. The human monocytic cell line THP-1 and the freshly isolated human monocytes, purified by adherence or elutriation from venous blood from healthy donors, were exposed to medium alone containing 1 mg/ml bovine serum albumin, HDL, LPS (parent LPS) and LPS-HDL complexes. mRNA level was analyzed on Northern blot, and cell-associated protein and supernatants were tested for IL-1 production using immunologic and biologic assays. LPS stimulates substantially more IL-1 mRNA and cell-associated IL-1 protein when the monocytes are stimulated with LPS alone versus LPS-HDL. These data suggest that LPS-HDL complexation may contribute to a reduction in endotoxic activities in vivo by preventing LPS (lipid A) from generating important transmembrane signals after binding to cells.

Blotting, Northern↗

PubMed1988

Differential effects of in vitro mycoplasma infection on interleukin-1 alpha and beta mRNA expression in U937 and A431 cells.

Cultured cells depend on cytokine mediators for sustained growth and maintenance and are routinely employed in bioassays to detect and measure minute changes in biological mediators, e.g. the interferons and interleukins. We evaluated the effects of mycoplasma infection on the steady-state mRNA levels of two cytokines IL-1 alpha and beta. Noninfected human squamous carcinoma cell line A431 expressed constitutively IL-1 alpha and beta mRNA. In contrast freshly isolated peripheral blood mononuclear cells and the monocytic cell line U937 expressed abundant IL-1 mRNA only after the appropriate stimulation. Peripheral blood mononuclear cells and U937 steady-state IL-1 beta mRNA levels were considerably greater than IL-1 alpha mRNA levels, whereas nearly equivalent high levels of IL-1 alpha and beta mRNA were detected in A431 cells. Mycoplasma infection of cultured A431 cells reduced the steady-state levels of IL-1 alpha and beta mRNA. This effect was nonspecific for A431 cells as actin mRNA steady-state levels showed similar decreases to mycoplasma contamination. However, this response was cell specific since mycoplasma-free and contaminated U937 cells differed little in IL-1 mRNA expression. These results show that the response to mycoplasma infection is at least partly cell-type dependent.

Cell Line↗

PubMed1987

Expression of human IL 1 alpha and beta messenger RNAs and IL 1 activity in human peripheral blood mononuclear cells.

The macrophage-derived lymphokine interleukin 1 (IL 1) plays a critical role in modulating immune (cellular and humoral) and nonimmune responses. For example, the relative expression of IL 1 alpha and beta under various states may be crucial to the success of the immune system in response to infection. Until recently, a comparative study of IL 1 mRNA expression and IL 1 biological activity was not possible. We have cloned both IL 1 alpha and beta cDNAs and employed them as probes in Northern blot analysis to determine in mitogen-stimulated peripheral blood mononuclear cells the steady-state expression of their cognate mRNAs with respect to IL 1 activity. IL 1 was determined by the lymphocyte-activating factor (IL 1/LAF) and the mononuclear cell factor (IL 1/MCF) activities. In lectin-stimulated PBMC, maximum cell-associated activities whereas detected at 12 and 24 hr after stimulation whereas maximum extracellular activities appeared between 24-48 hr. In the same cultures, the kinetics of IL 1 mRNA steady-state expression were determined by Northern gel blot analysis with IL 1 alpha and beta cDNA probes. IL 1 mRNAs were undetectable in noncultured freshly isolated PBMC (time zero). Both IL 1 mRNAs appeared as early as 4 hr after lectin stimulation as did IL 1 beta mRNA in unstimulated cultures. Both IL 1 alpha and beta mRNA steady-state levels were barely detectable by 48 hr. At all time points, IL 1 mRNA levels were considerably lower in unstimulated cultures. IL 1 beta mRNA was always considerably more abundant than IL 1 alpha mRNA. The less abundant IL 1 alpha mRNA showed a decrease in its stead-state levels prior to the reduction in the levels of IL 1 beta mRNA. TNF alpha activity and mRNA were not detected under these culture conditions. Poly(A) + RNA injected into Xenopus oocytes revealed that the Northern blot detected IL 1 mRNAs were biologically active. To understand the precise nature of IL 1 in immune and nonimmune events, we felt it necessary to first study the kinetics of IL 1 mRNA steady-state levels with respect to its cell-associated and extracellular biological activities. The data presented here may allow for a better understanding of the etiology of various immune and nonimmune responses that are modulated through the expression of IL 1.

Animals↗