[Systemic nocardiosis with mediastinal lymph node involvement proven by endoscopic ultrasound]

INTRODUCTION

Systemic nocardiosis is an infectious disease that is rarely associated with mediastinal lymph nodes.

CASE REPORT

We report the case of a 72-year-old male patient treated with a high dose of oral corticosteroids for rheumatoid polyarthritis. This patient presented with rapid overall deterioration associated with mediastinal lymph nodes. Endobronchial ultrasound enabled us to establish a diagnosis of systemic nocardiosis. The patient recovered after having received suitable antibiotic treatment for four months.

CONCLUSION

This work reports on a rare clinical presentation of systemic nocardiosis associated with mediastinal lymphadenopathies and highlights the key role of endobronchial ultrasound in diagnosing mediastinal lymph nodes, especially in differential diagnosis for lung cancer.

[Effects of fine particulate matter from on bronchial epithelial cells]

INTRODUCTION

Ambient air contains a variety of pollutants including solid particles. Human bronchial epithelial cells (HBEC) play a key role following inhalation of these toxic particles. In a cell culture system of HBEC, we investigated the effects of several fractions of Lyons air-derived particles on cell viability/proliferation and production of the inflammatory mediators IL-8 and TGF-β.

METHODS

Air particles were collected in Lyon (France) by filtration of the air and impaction on filters located on a tapered element oscillating microbalance. Several diameter-based fractions of particles were prepared. HBEC were then exposed to different concentrations of these fractions.

RESULTS

HBEC survival was not altered after 48hours of culture in the presence of particles regardless of their diameter and concentration. A dose-dependent inhibitory effect on cell growth was observed for all fractions. The particles caused an increase of both TGF-ß and Il-8 protein levels as a function of their diameters and/or concentrations.

CONCLUSION

Air-derived particle fractions exhibit both an inhibitory effect on cell proliferation and a pro-inflammatory activity on HBEC.

Impairment of human immunodeficiency virus type-1 integrase SUMOylation correlates with an early replication defect

HIV-1 integrase (IN) orchestrates the integration of the reverse transcribed viral cDNA into the host cell genome and participates also in other steps of HIV-1 replication. Cellular and viral factors assist IN in performing its multiple functions, and post-translational modifications contribute to modulate its activities. Here, we show that HIV-1 IN is modified by SUMO proteins and that phylogenetically conserved SUMOylation consensus motifs represent major SUMO acceptor sites. Viruses harboring SUMOylation site IN mutants displayed a replication defect that was mapped during the early stages of infection, before integration but after reverse transcription. Because SUMOylation-defective IN mutants retained WT catalytic activity, we hypothesize that SUMOylation might regulate the affinity of IN for co-factors, contributing to efficient HIV-1 replication.

Chronic biliary drainage corrects liver atrophy induced by portacaval shunt in the rat

Portacaval shunt induces a severe liver atrophy. The relative liver hypertrophy induced by chronic biliary drainage was studied by electron microscopy. Rats with either portacaval or sham portacaval shunt had a 4-day chronic bile fistula. Compared with rats not submitted to chronic bile fistula, liver weight/body weight ratio increased from 1.84 to +/- 0.12 to 3.54 +/- 0.48 (p less than 0.05) in portacaval shunt and from 3.52 +/- 0.15 to 3.64 +/- 0.40 (p less than 0.05) in sham portacaval shunt (controls). Chronic bile fistula stimulated bile acid synthesis in the two groups. Furthermore, the initial low bile flow observed in portacaval shunt (rats) reached control values after chronic bile fistula. Ultrastructural abnormalities observed in portacaval shunt: atrophy of the hepatocyte mainly related to the atrophy of the rough and smooth endoplasmic reticulum, irregularity of the nucleus, dilatation of the nuclear envelope and of the rough endoplasmic reticulum, and swelling of mitochondria, were greatly modified by chronic bile fistula. The hepatocyte size increased, mitochondria appeared smaller than normal, the nuclear envelope and the rough endoplasmic reticulum were not dilated, and the rough and smooth endoplasmic reticulum were expanded. Chronic bile fistula had no noticeable effect on the liver in sham portacaval shunt. Either stimulation of bile salts synthesis or removal of bile salts, which could be toxic for the atrophic liver, are possible explanations for the relative hypertrophy of the liver.

[Metabolism of bile salts. 2 - The cholanopathies (author's transl)]

A better understanding of the mechanisms of bile acid metabolism, coupled with advances in methodology, has shown the major part played by bile salts in the pathogenesis of several diseases, such as cholesterol cholelithiasis, secretory diarrhoea and/or steatorrhoea associated with diseases of the small intestine, etc. This in turn has helped to develop effective medical treatments for some of these conditions. Considerable progress has also been made in determining the abnormalities in bile acid metabolism found in parenchymal and cholestatic liver diseases and in rare conditions associated with inborn errors in bile acid synthesis. The clinician's approach to diagnosis and treatment has thus been thoroughly modified by improved knowledge of bile acid metabolism.

[Metabolism of bile salts. 1. Control of synthesis (author's transl)]

Bile acids, which are essential to the digestion of fat, are synthetized in the liver from cholesterol, and changes in synthesis usually parallel changes in cholesterol synthesis. Mainly located in the gallbladder and intestine, they circulate several times a day between these two organs (enterohepatic circulation). The pool of bile salts remains constant, the amount synthetized daily being equal to those lost through the faeces. Bile acid synthesis is controlled by a feed-back mechanism represented by the amount of bile salts reaching the sinusoidal membranes of liver cells.