Search PubMed⌕ Search

Biomedical subjects

A Schaffner

Publications and source records attributed to A Schaffner.

At least 19 recordsLinked to original sources
PubMed1997

Nitrite generation in interleukin-4-treated human macrophage cultures does not involve the nitric oxide synthase pathway.

The search continues for high-output nitric oxide biosynthesis in human macrophages analogous to murine phagocytes. Recently, generation of nitrite in culture supernatants of human macrophages exposed to interferon-gamma and interleukin-4 (IFN-gamma/IL-4) was reported. The present study reproduces these findings and shows that L-arginine is not consumed and L-citrulline is not produced during this process. Furthermore, the biosynthesis of the obligatory cofactor tetrahydrobiopterin is not coinduced. These biochemical data provide support against a nitric oxide synthase contribution to nitrite accumulation. Nitrite was generated from nitrate salts even in cell-free media. Nitric oxide synthase activity but not nitrate reduction depended on molecular oxygen. Nitrite accumulation in experiments with IFN-gamma/IL-4 in human monocytes appears to be an in vitro artifact produced by nitrate-reducing activities contained in cytokine preparations.

Amino Acids↗
PubMed1996

Effects of activating and deactivating cytokines on the functionally linked tetrahydrobiopterin. No pathways in vascular smooth muscle cells.

The functional relationship of nitric oxide (NO) production and synthesis of tetrahydrobiopterin (BH4), the requisite cofactor for NO synthase, was investigated in rat aortic smooth muscles cells (SMC). Inflammatory cytokines induced BH4 and NO synthesis in different ratios, IL-1 beta induced mainly NO synthesis with concomitant but limiting amounts of BH4 for maximal NO production. TNF alpha did not induce NO synthesis but induced BH4 synthesis. IFN gamma was ineffective on both the induction of NO and BH4 synthesis. TGF beta downregulated NO production but did not affect BH4 biosynthesis. IL-4 and IL-10 had no effect on both BH4 and NO synthesis. Activating cytokines strongly synergized in induction of NO production, whereas endogenous BH4 production became insufficient for maximal NO synthesis. Exogenous cofactor in the form of sepiapterin or authentic BH4, but not the natural isomer 7-BH4, enhanced NO production twofold. Inhibition of BH4 synthesis with dicumarol abolished NO production that could be restored in the presence of BH4.

Animals↗
PubMed1996

[Fungal infections in primary care].

Fungal infections are of minor importance in general practice. With the possible exception of cryptococcosis in HIV-infected patients deep fungal infections are rarely seen in ambulatory medicine. Some exceptions are discussed. Candida spp. are normally found on the surfaces of the gastrointestinal and genital tract. The documentation of yeast from these sites is therefore not an indication for antifungal therapy. Esophagitis oral or vaginal thrush should however be treated promptly with oral fluconazole. Cutaneous mycoses are best treated topically or if too extensive with itraconazole or terbinafine. Treatment of nail infection, if treatment is warranted at all is best treated with terbinafine. Any attempts to attribute uncharacteristic complaints to an intestinal colonization with yeasts or nutritional fungal toxins lacks a scientific background. The practice to diagnose from blood films obscure fungal infections is quackery at best.

Antifungal Agents↗
PubMed1996

Spondylodiscitis caused by Tropheryma whippelii.

We describe the first case of spondylodiscitis caused by Tropheryma whippelii in which this so far unculturable organism was shown to be present at the site of infection in a patient without significant gastrointestinal symptoms. The methods used included broad-range PCR amplification with universal primers complementary to constant sequences of the gene coding for 16S rRNA, direct sequencing of the amplified fragment, and comparison of the sequence determined with those deposited in sequence databases. In addition to demonstrating the presence of this organism in the affected vertebral body, we found in our patient that the specific PCR is more sensitive than histology for detecting Whipple's bacilli in bowel biopsy specimens. Because histology of small bowel biopsies from the duodenum were-in contrast to PCR from the same site-not diagnostic for Whipple's disease in our patient, we recommend PCR whenever Whipple's disease has to be excluded.

Actinobacteria↗
PubMed1996

Comparison of the antimicrobial activity of deactivated human macrophages challenged with Aspergillus fumigatus and Listeria monocytogenes.

The anticonidial activity of human monocytes deactivated by cytokines interleukin (IL)-4 and IL-10 and the hormone dexamethasone was studied and compared with antilisterial activity. Dexamethasone had the largest effect on the anticonidial activity and suppressed germination-inhibiting activity and elimination of ingested spores by macrophages more than the cytokines did. Maximally active concentrations of IL-10 had a similar but significantly smaller deactivating effect. IL-4, in contrast to IL-10 and dexamethasone, did not reduce anticonidial activity. However, IL-4 and IL- 10 were equally potent in deactivating human macrophages against Listeria monocytogenes, whereas dexamethasone was significantly less potent in the Listeria model. These observations indicate that all three mediators lessen antimicrobial activity but that this effect depends on the test organism studied and is apparently mediated through regulation of different antimicrobial systems operating against a particular microorganism.

Aspergillus↗
PubMed1996

Sweet's syndrome involoving the musculoskeletal system during treatment of promyelocytic leukemia with all-trans retinoic acid.

Induction therapy of promyelocytic leukemia with all-trans retinoic acid is a standard therapy despite significant side-effects. The most important, the "retinoic acid syndrome", consists of a hyperinflammatory reaction with capillary leakage (edema, pleural, and pericardial effusion), infiltration of myeloid cells into internal organs and systemic signs of inflammation. We describe here two cases of another hyperinflammatory reaction during all-trans retinoic acid therapy, the Sweet's syndrome, consisting of infiltrates of the skin and internal organs by neutrophilic granulocytes. Fever, painful erythematous cutaneous plaques, prominent musculoskeletal involvement (myositis, fasciitis), a sterile pulmonary infiltration and intercurrent proteinuria characterized the clinical course of all-trans retinoic acid-associated Sweet's syndrome. Treatment with glucocorticoids led to resolution of the syndrome within 48 h. Three other cases of all-trans retinoic acid-associated Sweet's syndrome without involvement of internal organs, prominent on our cases, were published previously. Recognition of ATRA-associated Sweet's syndrome is of practical importance.

Adult↗
PubMed1995

Modulation of the antilisterial activity of human blood-derived macrophages by activating and deactivating cytokines.

A concept of macrophage deactivation by hormones and cytokines that opposes activation was recently proposed. Deactivation of the antilisterial activity of macrophages by IL-4, IL-10, and TGF-beta, as well as by dexamethasone, was studied here. IL-4, IL-10, and dexamethasone, but not TGF-beta, caused a complete loss of the competence of human blood-derived macrophages infected with Listeria monocytogenes to control or eliminate ingested bacteria. IL-10 and, to a lesser degree, dexamethasone lessened in parallel the capacity of macrophages to secrete H2O2. The antilisterial activity of cells simultaneously exposed to deactivating agents could be significantly augmented by IFN-gamma. Likewise, TNF-alpha and to a limited degree GM-CSF increased the antilisterial activity of cells treated with IL-10 and dexamethasone but not that of cells treated with IL-4. Suppression of TNF-alpha secretion in response to Listeria by TGF-beta, IL-10, dexamethasone, or pentoxifylline did not closely parallel antilisterial activity. Studies by transmission electron microscopy and actin staining suggested that deactivation by IL-10, IL-4, and dexamethasone of human blood-derived macrophages resulted in intraphagosomal multiplication of Listeria followed only then by an escape of bacteria into the cytoplasm. The antibacterial competence of human macrophages is lessened by IL-4 and IL-10 and augmented by IFN-gamma, TNF-alpha, and GM-CSF. The success of human macrophages in controlling intracellular pathogens appears to depend on the balance of activating and deactivating mediators modulating their activity.

Cytokines↗
PubMed1995

Nitric oxide and infection: another view.

Nitric oxide (NO) has been nicknamed "murderer" and "mediator" because it has toxic and signaling properties. We review these two aspects of NO synthesis from the perspective of the clinical infectious disease specialist by considering the potential of NO as an endothelium-derived relaxing factor (EDRF) in inflammation and sepsis and its potential as an antimicrobial system. We deviate from observations in recent authoritative reviews and point to important species differences that make it unlikely that NO serves as an EDRF mediating inflammatory vasodilatation in humans or that NO synthesized by humans phagocytes has an antimicrobial function. We propose that in humans, No synthesis is more confined and compartmentalized than in certain other animal species, and therefore, unwelcome toxicity, vasodilatation, or disturbance of paracrine signaling mechanisms (i.e., modulation of phagocytic cell functions) are avoidable during inflammation.

Animals↗
PubMed1995

Effect of prophylactic fluconazole on the frequency of fungal infections, amphotericin B use, and health care costs in patients undergoing intensive chemotherapy for hematologic neoplasias.

Fungal infections are a major problem in patients with hematologic malignancy. Attempts to reduce their frequency with antifungal agents have not been successful. A double-blind, controlled, single-center trial was conducted with 96 consecutive patients undergoing 154 episodes of chemotherapy. Patients received 400 mg of fluconazole or placebo until bone marrow recovery or initiation of intravenous amphotericin B infusions. End points were amphotericin B use, fungal infection, stable neutrophil count > 0.5 x 10(9)/L, toxicity precluding further fluconazole use, and death. By Kaplan-Meier estimation, the time to initiation of amphotericin B therapy was shorter in 76 patients treated with placebo than in 75 treated with fluconazole (P = .003). Also, fluconazole reduced the number of febrile days by 20% (P = .002) and prevented oropharyngeal candidiasis (1/75 vs. 9/76, P = .018). The frequency of deep mycoses (8/76 vs. 8/75) and outcome were unaffected. Fluconazole did not have a favorable effect on infection-related health care costs and was associated with prolonged severe neutropenia (P = .01).

Adult↗
PubMed1994

Tetrahydrobiopterin as another EDRF in man.

Endotoxin and inflammatory cytokines downregulate expression of constitutive nitric oxide synthase (cNOS) in human vascular endothelial cells with concomitant increase of tetrahydrobiopterin synthesis in these cells and parallel upregulation of inducible NOS expression in smooth muscle cells, indicating compartmentalized nitric oxide (NO) production under septic conditions in man. In this report the compartmentalization has been further studied using dual chamber cell cultures with inflammatory activated human endothelial cells. We show that endothelial cells secrete BH4 vectorially into the basal direction thereby providing underlining smooth muscle cells with the cofactor necessary for NO production. Furthermore, by laser Doppler velocimetry we show that intraarterial infusion of BH4 induces strong vasodilatation in man. Consumption of L-arginine and production of cyclic GMP increased and therefore imply NO as second messenger. Thus the discovery of an endothelium-derived factor regulating NOS activity would reconcile the concept of an inflammatory EDRF that is not NO itself but results in NO-dependent vasodilatation in man.

Animals↗
PubMed1994

Tetrahydrobiopterin is a secretory product of murine vascular endothelial cells.

Tetrahydrobiopterin (BH4) is an obligatory cofactor of nitric oxide synthase and an essential regulator of its activity. The murine vascular endothelial cell line send1 constitutively secretes large amounts of BH4 as well as scant amounts of neopterin, an oxidized intermediate in the de novo biosynthesis of BH4. Further enhancement of BH4 and neopterin secretion is achieved by activation with endotoxin (LPS) and interferon-gamma. This finding is in accordance with previous described BH4 secretion by human endothelial cells. It supports the view that endothelial cells are the source of BH4 serving vascular needs in vivo. In septic conditions, BH4 released by endothelial cells in large amounts could serve induced nitric oxide synthase in smooth muscle cells, thereby acting as another endothelium-derived relaxing factor mediating vasodilatation.

Animals↗
PubMed1994

Differential regulation of constitutive and inducible nitric oxide production by inflammatory stimuli in murine endothelial cells.

The murine vascular endothelial cell line send1 expresses both constitutive and inducible nitric oxide (NO) synthases. Interferon-gamma (IFN gamma) or endotoxin (LPS) alone inhibited constitutive NO production in a dose and time dependent manner. Addition of L-arginine had no influence on the decrease of NO production caused by IFN gamma or LPS. On the other hand, IFN gamma and LPS synergized in the induction of high output NO production. Successive incubations with IFN gamma and LPS in different sequences revealed IFN gamma as the time setting signal for the induction of NO synthesis. These results demonstrate that LPS and IFN gamma have a direct suppressive effect on constitutive NO synthase while at the same time they strongly activate inducible NO production. Thus inflammatory stimuli trigger murine vascular endothelial cells to switch from constitutive to inducible NO synthase activity.

Animals↗
PubMed1994

[Infectious endocarditis].

The diagnosis of infective endocarditis remains a challenge to physicians providing primary care. On one hand this type of infection will be rarely encountered in primary care, but on the other hand this disease carries an enormous detrimental potential. Furthermore infective endocarditis, particularly in its initial phase, often has an uncharacteristic presentation with findings and symptoms shared with many much more frequent and often harmless diseases. To confront these difficulties, which are responsible for the often delayed diagnosis of infective endocarditis, strict rules must be applied. In patients at risk for infectious endocarditis no antibiotic therapy should be instituted without prior cultures. Also, in all other patients aimless, "blind" antibiotic therapy without diagnosis of a bacterial infection should be avoided. In patients with uncharacteristic symptoms and findings compatible with the diagnosis of infective endocarditis that persist for more than 5 days, blood cultures prior to any antibiotic therapy are warranted in addition to other clinical exams and tests. The sensitivity of echocardiography in detecting infective endocarditis is frequently overestimated. Furthermore, transesophageal echocardiography in endocarditis high-risk patients requires antibiotic prophylaxis which would obscure bacteriological diagnosis. For these reasons echocardiography should not be used as first test method when considering the diagnosis of infective endocarditis.

Abscess↗
PubMed1994

[Alcoholic pellagra encephalopathy: an underestimated treatable entity].

Alcoholic pellagra-encephalopathy is an underestimated entity, which is characterized by alteration in the level and content of consciousness, marked oppositional hypertonus and myoclonus. This entity should be included in the differential diagnosis of encephalopathy in ethanol abusers. The spontaneous course is potentially lethal. Therapy consists of substitution of nicotinic acid in the form of nicotinamide. It is emphasized that any chronic ethanol abuser with neurological symptoms should receive substitution of all B-group vitamins including nicotinamide.

Alcoholism↗
PubMed1994

Nitric oxide production depends on preceding tetrahydrobiopterin synthesis by endothelial cells: selective suppression of induced nitric oxide production by sepiapterin reductase inhibitors.

Using murine vascular endothelial cells expressing both constitutive and inducible nitric oxide synthases (cNOS and iNOS), we explored the feasibility of suppressing cytokine-induced nitric oxide (NO) production without affecting constitutive NO production by inhibition of the tetrahydrobiopterin (BH4) biosynthesis. We show in this study that in endothelial cells cytokine/endotoxin-activated BH4 synthesis precedes the induction of NO generation. Using the sepiapterin reductase inhibitors phenprocoumon or dicumarol as BH4 synthesis inhibitors, we achieved a pronounced and selective suppression of induced NO production in cytokine-activated endothelial cells. Addition of exogenous BH4, but not sepiapterin, restored NO production in the presence of the inhibitors. Despite profound inhibition of the BH4 biosynthesis, constitutive NO synthesis was not affected, thereby demonstrating the selectivity and specificity of the inhibitors. Suppression of enhanced NO production by sepiapterin reductase inhibitors such as cumaroles could provide pharmacologic means for therapeutic interventions in NO-mediated pathophysiologic events.

Alcohol Oxidoreductases↗
PubMed1994

Fatal hematophagic histiocytosis after granulocyte-macrophage colony-stimulating factor and chemotherapy for high-grade malignant lymphoma.

Fatal hematophagic histiocytosis occurred in two patients after they had received granulocyte-macrophage colony-stimulating factor (GM-CSF) in addition to chemotherapy for malignant non-Hodgkin's lymphoma. In one patient GM-CSF promoted the activity of subclinical hematophagic histiocytosis, resulting in severe pancytopenia and multiorgan failure. In the other patient the syndrome that caused persistent bone marrow failure began after the institution of GM-CSF therapy. Exogenous GM-CSF appears to upregulate preexisting hematophagic histiocytosis and may even contribute to its de novo initiation. It is therefore conceivable that endogenous GM-CSF also plays an essential role in the pathogenesis of this syndrome.

Adult↗