Diel and seasonal variations in abundance, activity, and community structure of particle-attached and free-living bacteria in NW Mediterranean Sea.

Diel and seasonal variations in abundance, activity, and structure of particle-attached vs free-living bacterial communities were investigated in offshore NW Mediterranean Sea (0-1000 m). Attached bacteria were always less abundant and less diverse but generally more active than free-living bacteria. The most important finding of this study was that the activity of attached bacteria showed pronounced diel variations in the upper mixed water column with higher activities at night. Under mesotrophic conditions, the contribution of attached bacteria to total bacterial activity increased from less than 10% at day time to 83% at night time. At high chlorophyll a concentration, the highest cell-specific activities and contribution to total bacterial activity were due to free-living bacteria at day and to attached bacteria at night. Under summer oligotrophic conditions, free-living bacteria dominated and contributed to the most important part of the bacterial activity at both day and night, whereas attached bacteria were much less abundant but presented the highest cell-specific activities. These diel and seasonal variations in activities were concomitant to changes in bacterial community structure, mainly in the upper layer. The number of attached ribotypes was fairly constant suggesting that particles are colonized by a relatively limited number of ubiquitous ribotypes. Most of these ribotypes were also free-living ribotypes suggesting that attached bacteria probably originate from colonization of newly formed particles by free-living bacteria in the upper layer. These results reinforce the biogeochemical role of attached bacteria in the cycling of particulate organic carbon in the NW Mediterranean Sea and the importance of diel variability in these processes.

Incorporating out-patient data from CD-R into the local PACS using DICOM worklist features.

With the introduction of digital imaging in radiology, CD-Rs are increasingly used to distribute patient materials. This study investigates the application of a new software package and work protocol to integrate out-hospital data into the local PACS (picture archive and communication system) archive, which is hampered by differences in patient numbers. A one-month trial was started to import CD-Rs from two departments (radiotherapy and radiology). Seventy CD-Rs were collected from 20 different hospitals holding data of eight different modality types and published by eight different software packages from different vendors. All CD-Rs were successfully transferred into the PACS. The new software and work protocol provide an easy way of introducing the out-hospital data into the PACS. CD-Rs can be destroyed after transfer to PACS, eliminating physical storage. Furthermore, all data can now be viewed and reported using the default viewers of the hospital and no additional training of staff is required.

Heterotrophic nitrification by a thermophilic Bacillus species as influenced by different culture conditions.

The nitrification activity of a thermophilic heterotrophic bacterium, Bacillus MS30 isolated from a deep-sea hydrothermal vent, was studied under various growth conditions. Nitrification was estimated from the nitrogen balance calculations in the culture media. The results showed that this isolate actively nitrified in culture conditions similar to those prevailing in hydrothermal sites. Therefore, its ecological significance was considered. In standard aerobic conditions, MS30 produced nitrite from ammonia and acetate (1.13 mumol NO2-.mg-1 dry wt), but nitrate was never produced, and a low nitrite reduction was often observed. Higher nitrification activities were observed in defined optimal conditions (simple carbon substrate, 65 degrees C, pH 7.5, and 15 g sea salts.L-1). In addition, discrepancies between the optima for growth and nitrification were observed, showing the ability of MS30 to adapt to changing environmental conditions typical of hydrothermal sites.

[Epidemiology of stroke in Guadeloupe and role of sickle cell trait]. / Epidémiologie des accidents vasculaires cérébraux en Guadeloupe et rôle du trait drépanocytaire.

Sickle cell disease (homozygotes SS) is known as a risk factor for both ischemic and hemorrhagic stroke, but heterozygotes AS seem to be spared. We carried out a retrospective study to assess the main risk factors and the influence of hemoglobin abnormalities on stroke in Guadeloupe. The percentages of AS, AC, and AA on 295 patients admitted for stroke were compared to the prevalence obtained on 72,000 newborn babies. Ischemic, hemorrhagic stroke and stroke complications represented respectively 83 p. 100, 10 p. 100 and 7 p. 100. Seventy one per 100 of patients had hypertension and 19 p. 100 had an association of diabetes and hypertension. The percentage of heterozygotes AS was significantly lower in the group with ischemic stroke (4 p. 100) in comparison with controls (8.5 p. 100), while AS were more represented in hemorrhagic stroke (16 p. 100). The risk of hemorrhagic stroke was 10 fold higher in AS patients admitted for stroke and the risk of ischemic stroke was reduced by 15 fold. These data suggest that the sickle cell trait could be associated to red cell and/or endothelial specificities which could prevent for ischemic stroke. The influence of AS heterozygote on the occurrence of stroke needs to be examined in a longitudinal, prospective study.