Lyme borreliosis

Lyme disease is a multisystemic disease caused by a spirochete, Borrelia Burgdorferi that is transmitted by ticks. A clinical diagnosis is easy when a tick bite is followed 3 weeks later by erythema migrans, than by involvement of nervous system, joints or heart. In case of neuroborreliosis, serological tests, performed in blood and cerebro-spinal fluid, support the diagnosis and patients recover rapidly with antibacterial treatments. However an accurate diagnosis remains sometimes problematic, especially distinction between a coincidental positive serologic test and a nervous system Lyme borreliosis which require antibiotics. Furthermore, the role of autoimmunity in the pathophysiology of late Lyme disease, antibiotic choice in early disease, duration of treatment, and utility of vaccination are discussed.     

Radiation-induced aneurysm of the cavernous internal carotid artery

We report a case of intra-cranial aneurysm of the left cavernous internal carotid artery occurring 27 years after radiotherapy of the pterygopalatine fossa for Hodgkin disease. The development of the aneurysm within the irradiation field, the long latency after radiotherapy, the normality of carotid angiography before radiotherapy and the absence of other etiologies led to the diagnosis of radiation-induced aneurysm. The main characteristics of radiation-induced intra-cranial aneurysms are reviewed.     

Differential survival of solitary and aggregated bacterial cells promotes aggregate formation on leaf surfaces

The survival of individual Pseudomonas syringae cells was determined on bean leaf surfaces maintained under humid conditions or periodically exposed to desiccation stress. Cells of P. syringae strain B728a harboring a GFP marker gene were visualized by epifluorescence microscopy, either directly in situ or after recovery from leaves, and dead cells were identified as those that were stained with propidium iodide in such populations. Under moist, conducive conditions on plants, the proportion of total live cells was always high, irrespective of their aggregated state. In contrast, the proportion of the total cells that remained alive on leaves that were periodically exposed to desiccation stress decreased through time and was only approximately 15% after 5 days. However, the fraction of cells in large aggregates that were alive on such plants in both condition was much higher than more solitary cells. Immediately after inoculation, cells were randomly distributed over the leaf surface and no aggregates were observed. However, a very aggregated pattern of colonization was apparent within 7 days, and >90% of the living cells were located in aggregates of 100 cells or more. Our results strongly suggest that, although conducive conditions favor aggregate formation, such cells are much more capable of tolerating environmental stresses, and the preferential survival of cells in aggregates promotes a highly clustered spatial distribution of bacteria on leaf surfaces.