Clara Larcher

Regulatory Interactions between Iron and Nitric Oxide Metabolism for Immune Defense against Plasmodium falciparum Infection

Iron chelation therapy of Plasmodium falciparum infection alleviates the clinical course of cerebral malaria in children. This study assessed the underlying mechanisms of this therapy. Cytokine stimulation of human (intestinal cell line DLD-1) or murine cells (murine macrophage cell line RAW 264.7) resulted in increased nitric oxide (NO) formation and decreased survival of plasmodia within cocultured human erythrocytes. The addition of desferrioxamine (DFO) before cytokine treatment increased both NO formation and parasite killing but had no effect in the presence of the inhibitor of NO formation, L-N6-(1-iminoethyl)-lysine. Moreover, peroxynitrite, which is formed after chemical reaction of NO with superoxide, appears to be the principal effector molecule for macrophage-mediated cytotoxicity toward P. falciparum, and interferon-gamma is a major regulatory cytokine for this process. The effect of DFO on the clearance of plasmodia appears to be due to enhanced generation of NO, rather than to limitation of iron availability to the parasite.

Epstein-Barr virus-associated multicentric leiomyosarcoma in an adult patient after heart transplantation: case report and review of the literature.

Epstein-Barr virus (EBV)-associated smooth muscle tumors following solid organ transplantation are extremely rare, with only 12 cases reported in the literature thus far. The exact pathogenetic role of EBV infection in the oncogenesis of these soft tissue tumors in immunodeficient patients and the biologic behavior of such tumors is still unclear. We report a 26-year-old man in whom multiple smooth muscle tumors developed 36 to 51 months after heart transplantation. All tumors, two synchronous liver nodules, two subsequently occurring paravertebral tumors, and a single tumor in a vein at the left ankle were surgically resected. The tumor tissue was processed for routine histology and immunohistochemical (IHC) stains. Additionally, competitive polymerase-chain-reaction (PCR), reverse-transcriptase PCR (RT-PCR), as well as in situ hybridization (ISH) were used for EBV particle quantification and gene transcription analysis. The histologic features and immunohistochemical profiles were consistent with leiomyosarcoma in all tumor nodules. EBV infection was detected in >95% of tumor cell nuclei by EBER 1/2 ISH. Competitive PCR revealed 3105 EBV particles per milligram of tumor tissue. The EBV gene expression pattern analyzed by RT-PCR and IHC corresponded to the latency type III with specific expression of EBNA1, EBNA2, LMP1, and LMP2A genes. Under continuous antiviral therapy (famcyclovir) the patient currently shows no evidence of disease. Our data indicate that EBV infection plays a causal role in the development of smooth muscle tumors following organ transplantation. A latency type III, identical to EBV-associated posttransplant lymphoproliferative disorders, was identified and suggests a common pathogenetic mechanism in the development of these histogenetically distinct neoplasms. The fact that the patient currently shows no evidence of disease may be the result of the continuous administration of antiviral therapy because the soft tissue recurrences of the leiomyosarcoma occurred while the patient was not receiving antiviral prophylaxis.

Detection of enteroviral ribonucleic acid in myocardial biopsies from patients with idiopathic dilated cardiomyopathy by polymerase chain reaction

Infection by enteroviruses, especially by Coxsackie B viruses, has been incriminated in pathogenesis of dilated cardiomyopathy. We developed polymerase chain reaction tests for the detection of enteroviral and Coxsackie B3 genomes, respectively, in myocardial biopsies obtained from a homogeneous group of 19 patients with idiopathic dilated cardiomyopathy. To determine unambiguously the incidence of enteroviruses and Coxsackie B3 viruses in these patients, we used two primer pairs, one common to all enteroviruses and the other specific for Coxsackie B3 viruses. In six patients of the dilated cardiomyopathy group, enteroviral ribonucleic acid (RNA) could be detected; only one was subspecified as Coxsackie B3 RNA. In contrast, no enteroviral RNA could be detected in a contrast group of 21 patients with other cardiac disorders. These results suggest that enteroviruses other than Coxsackie B3 are causally linked to the pathogenesis of dilated cardiomyopathy.

Activity of N-chlorotaurine against herpes simplex- and adenoviruses

N-chlorotaurine, an essential weak oxidant produced by stimulated human leukocytes, is known to have bactericidal, fungicidal and vermicidal properties. This study for the first time demonstrates its virucidal activity. By viral suspension tests at incubation times between 5 and 60 min, virus titers of both Herpes simplex virus type 1 and 2 were reduced about 1.3-2.9 log10 and 2.8-4.2 log10 by 0.1 and 1%, (5.5 and 55 mM) N-chlorotaurine, respectively. Virus titer reduction of adenovirus type 5 between 15 and 60 min was 0.5-2.0 and 0.6-4.0 log10, respectively, by the same concentrations of N-chlorotaurine. These findings support a contribution of N-chlorotaurine in destruction of pathogens during inflammatory reactions and also the possibility of its application as an antiviral agent in human medicine.

Escherichia coli from Italy producing OXA-48 carbapenemase encoded by a novel Tn1999 transposon derivative.

OXA-48 is an emerging class D carbapenemase originally identified in isolates from Turkey ([14][1]) and subsequently detected in several European and north African countries ([10][2]). Klebsiella pneumoniae is the most common host for OXA-48, but the enzyme has also been detected in Escherichia coli

Linkage of acquired quinolone resistance (qnrS1) and metallo-β-lactamase (blaVIM-1) genes in multiple species of Enterobacteriaceae from Bolzano, Italy

OBJECTIVES Twenty-four of 209 oxyimino-cephalosporin- and/or aztreonam-resistant Enterobacteriaceae collected around Bolzano had reduced susceptibility or resistance to carbapenems and gave positive metallo-beta-lactamase (MBL) tests. Their resistance mechanisms were investigated. METHODS Resistances were identified by Vitek 2 and MIC tests and isolates were genotyped by PFGE. Resistance genes were identified by PCR and sequencing, and plasmids were transferred by conjugation and/or transformation. Plasmid-borne genes were identified by Southern blotting, and their genetic surroundings were investigated by PCR mapping. RESULTS The 24 isolates with positive EDTA/imipenem synergy tests had bla(VIM-1) carried on 40-150 kb plasmids. Imipenem MICs ranged from 2 to >32 mg/L, while those of meropenem and ertapenem were lower. The isolates included a clonal cluster of 10 Klebsiella pneumoniae, two other K. pneumoniae isolates, and diverse isolates of Escherichia coli (seven), Klebsiella oxytoca (three) and Citrobacter freundii (two). Six MBL producers were aztreonam-susceptible; the 18 aztreonam-resistant isolates had co-resident extended-spectrum beta-lactamases. bla(VIM-1) occurred as the first cassette in class 1 integrons, with aacA4 as the second cassette. Quinolone resistance gene qnrS1 was detected in 21 of 24 (87.5%) bla(VIM-1)-positive isolates versus 14 of 185 (7.6%) bla(VIM)-negative isolates (P < 0.0001), with 13 of the latter belonging to a clonal cluster of E. coli. qnrS1 was located on the same plasmids as bla(VIM-1) and aacA4, but was not closely linked, as judged by PCR mapping. CONCLUSIONS bla(VIM-1) has become disseminated among enterobacteria in a small Italian town. The frequent association of genes conferring carbapenem, aminoglycoside and quinolone resistance on single plasmids will facilitate co-selection.

Local administration of cidofovir for human papilloma virus associated skin lesions in transplant recipients

Human papilloma virus (HPV)‐associated diseases are increasingly diagnosed in solid organ recipients. Cidofovir (CDV) is a broad‐spectrum antiviral agent with activity against all human herpes viruses and HPV. From 2000–2004, a total of 1303 solid organ transplants (SOT) were performed at our center. Six transplant recipients were treated with topical CDV for HPV‐associated lesions. One cardiac recipient responded to a single injection of CDV into his recurrent anal condylomata. In a renal recipient with recurrent penile condylomata CDV was injected into the lesions four times (2 week interval) until lesions regressed. One renal recipient developed multiple vaginal and anal intradermal neoplasias, which relapsed after laser ablation. The lesions were repeatedly injected with CDV and completely disappeared. Two renal recipients with widespread verrucae vulgares were treated with CDV gel, which resulted in regression of the lesions. One patient developed donor derived verrucae vulgares on both transplanted hands, which responded to CDV gel. Four of the six patients were switched from calcineurin inhibitors (CNIs) to Sirolimus (SIR). CDV was found effective in the treatment of HPV‐associated skin lesions in SOT recipients. It needs to be determined whether switch from CNIs to SIR might have contributed to the beneficial effect of CDV.

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)

Determination of soluble CD21 as a parameter of B cell activation.

In this study we established a novel solid‐phase immunoassay for CD21 using the time‐resolved fluorescence of lanthanide chelates. The capture assay was able to detect concentrations of as low as 100 pg of CD21 antigen per millilitre of sample and was used for quantitative determination of CD21 in lysates of different cell lines as well as in patient serum specimens. CD21 was measured in lysates of tonsils and cell lines of B. T cell and myelomonocyte lineage, and appeared to consist of monomeric antigen under the detergent conditions used. Elevated levels of soluble CD21 were observed in serum of patients with Epstein Barr virus (EBV) infection, a disease known to be associated with polyclonal B cell activation, and in infection with the lymphotropic rubella virus. Significantly increased levels were also found in malignancies which are associated with EBV. In patients with nasopharyngeal carcinoma (NPC), a correlation with the titre of EBV‐specific IgA was observed, thus supporting a possible role of soluble CD21 as a marker for disease activity in certain malignancies. Our data suggest that measurement of soluble CD21 could serve as a marker for activation of the immune system and diseases involving the B cell lymphoid system. Possible mechanisms and functions of soluble CD21 are discussed.

Chronic active Epstein-Barr virus disease in a case of persistent polyclonal B-cell lymphocytosis

Summary. Persistent polyclonal B‐cell lymphocytosis (PPBL) is a rare haematological disorder. It is characterized by activated and morphologically atypical B lymphocytes and polyclonal IgM production and has been associated with female sex, cigarette smoking, and HLA‐DR7 expression.