A MeSH based intelligent search intermediary for Consumer Health Information Systems.

GIN Austria (Gesundheitsinformationsnetz Austria) offers patients and consumers reliable medical knowledge about diseases, wellness and disease management in an easy understandable way and enables them to quick and incessant access to informations about the Austrian health system and Austrian health organizations. To achieve full customer (patients, citizens) satisfaction to find relevant information we propose a concept of a vector-model oriented IR-Tool based on the controlled vocabulary of the MeSH Thesaurus (german version). By this approach users who are often not used to scientific terms and expressions are supported to build up their own query with MeSH Main Headings. In a second step broader and narrower Main Headings are added to the query vector by the system. For this calculation an adapted version of the Floyd-Warshall algorithm for directed, azyclic graphs is used. The tool is part of the GIN Search Modul, which will ease gathering health information from different heterogenous internet datasources.

A multilingual medical thesaurus browser for patients and medical content managers.

This paper introduces a user-friendly browser interface which integrates multilingual search and browsing functionalities within medical thesauri via the internet. The tool is being developed as part of the GIN Austria Patient Information System and is based on an adapted datamodel of the MeSH thesaurus. A prototype offers the possibility to build up queries and export lists of MeSH main headings collected during browsing the relevant MeSH trees. The thesaurus browser can be used both by patients and citizens to build queries based on a controlled vocabulary to match them with existing documents within GIN and by medical information managers to find out appropriate keywords for interactive tagging or indexing of medical contents. A key component of this tool is the flexible choice of different languages of the MeSH datasource as well as of the user interface. Both can be changed independently at any point during a session. Another central aspect is the use of the UMLS Metathesaurus in combination with localized Thesaurus versions due to existing international character set problems.

Detection of subgroups from flow cytometry measurements of heterotrophic bacterioplankton by image analysis.

BACKGROUND: Flow cytometry is an invaluable tool for the analysis of large series of samples in aquatic microbial ecology. However, analysis of the resulting data is often inefficient or does not reflect the complexity of natural communities. Because bacterioplankton assemblages frequently fall into several clusters with respect to their cellular properties, these subgroups seem to be a promising level of abstraction. Image analysis was used to detect clusters from flow cytometry data. The method was tested on a bacterial community under heavy protozoan grazing pressure. METHODS: A bivariate histogram of flow cytometry data was transformed into a gray-scale image for image analysis. After low-pass filtration, regional maxima were delimited by a watershed algorithm. The resulting areas were then used as gates on the original measurements. RESULTS: Three clusters could be detected from the bacterial assemblage. Protozoan grazing had a strong impact on the bacterial community, which could be analyzed in detail at the level of individual subgroups. CONCLUSIONS: Investigation at the level of bacterial subgroups allowed a more detailed analysis than whole-community statistics and delivered essential and ecologically meaningful information. Image analysis proved to be an adequate tool to detect the subgroups without a priori knowledge.

Size Selective Feeding in Cyclidium glaucoma (Ciliophora, Scuticociliatida) and Its Effects on Bacterial Community Structure: A Study from a Continuous Cultivation System.

Three aspects of size selective feeding by the scuticociliate Cyclidium glaucoma were studied in continuous cultivation systems. Firstly, grazing-induced changes in abundance, biomass, and size structure of a bacterial community were investigated. Secondly, we studied possible grazing-protection mechanisms of bacteria as a response to permanent presence of the predator. And finally, we were looking for potential feedback mechanisms within this predator-prey relationship, i.e., how the ciliate population reacted to a changed, more grazing-protected bacterial community. The first stage of the cultivation system consisted of the alga Cryptomonas sp. and the accompanying mixed bacterial community. These organisms were transferred to two second stage vessels, a control stage without ciliates and a second one inoculated with C. glaucoma. After the first week, the abundance of bacteria in the latter decreased by 60% and remained stable until the end of the experiment (65 d), whereas bacterial biomass was less affected (393 mg C L-1 during days 0-7, 281 mg C L-1 afterwards). The mean bacterial cell volume doubled from 0.089 mm3 to 0.167 mm3, which was mainly due to increasing cell widths. During the whole investigation period formation of colonies or filaments was not observed, but we found a clear feedback of ciliates on bacterial size. An increase in bacterial cell volume was always followed by a decline of the predator population, resulting in a yet undescribed type of microbial predator-prey relation. Literature and our own data on the optimal food size range grazed by C. glaucoma showed that bacterial cell width rather than length was responsible for that observed phenomenon. Finally, we suggest that uptake rates of spherical latex beads give only limited information on truly ingestible prey volumes and that prey geometry should be considered in future studies on size selective feeding of protists.

In situ classification and image cytometry of pelagic bacteria from a high mountain lake (gossenkollesee, austria).

We describe a procedure to measure the cell sizes of pelagic bacteria after determinative hybridization with rRNA-targeted fluorescently labeled oligonucleotide probes. Our approach is based on established image analysis techniques modified for objects simultaneously stained with two fluorescent dyes. It allows the estimation of biomass and cell size distribution and the morphological characterization of different bacterial taxa in plankton samples. The protocol was tested in a study of the bacterioplankton community of a high mountain lake during and after the ice break period. Cells that hybridized with a probe for the domain Bacteria accounted for 70% of the bacterial abundance (range, 49 to 83%) as determined by 4(prm1),6(prm1)-diamidino-2-phenylindole staining (K. G. Porter and Y. S. Feig, Limnol. Oceanogr. 25:943-948, 1980), but for >85% of the total biomass (range, 78 to 99%). The size distribution for members of the beta subclass of the Proteobacteria shifted toward larger cells and clearly distinguished this group from the total bacterial assemblage. In the surface water layer beneath the winter cover, bacteria belonging to the beta 1 subgroup constituted about one-half of the beta subclass abundance. The mean cell volume of the beta 1 subgroup bacteria was significantly less than that of the beta subclass proteobacteria, and the beta 1 subgroup accounted for less than 30% of the total beta subclass biovolume. Two weeks later, the biovolume of the beta Proteobacteria had decreased to the level of the beta 1 subgroup, and both the biovolume size distributions and cell morphologies of the beta Proteobacteria and the beta 1 subgroup were very similar. We could thus quantify the disappearance of large, morphologically distinct beta subclass proteobacteria which were not members of the beta 1 subgroup during the ice break period. Our results demonstrate that changes in biovolumes and cell size distributions of different bacterial taxa, and eventually of individual populations, reveal hitherto unknown processes within aquatic bacterial assemblages and may open new perspectives for the study of microbial food webs.

The ventrolateral medulla. A new site of action of the renin-angiotensin system.

High-affinity binding sites for angiotensin II (Ang II) in the ventrolateral medulla suggest that Ang II may act at cell groups that are known to modulate blood pressure. This hypothesis was investigated by the topical application of angiotensin I (Ang I), Ang II, the Ang II antagonist [Sar1, Thr8]Ang II, and the Ang I converting enzyme inhibitor MK 422 to a restricted region of the ventral medullary surface known as the glycine-sensitive area. Both Ang I (100 pmol) and Ang II (100 pmol) produced significant (p less than 0.01) increases in blood pressure (+20 +/- 4 and +31 +/- 5 mm Hg, respectively) that were associated with no change in heart rate. Furthermore, the relationship between the peak increases in blood pressure and Ang II was dose-dependent. Blockade of endogenous Ang II by [Sar1, Thr8]Ang II (13 nmol) produced a significant decrease in baseline blood pressure (-8 +/- 1 mm Hg; p less than 0.001). Similarly, topical application of MK 422 prevented the pressor effect of Ang I. Taken together, these experiments indicate that at least some components of the renin-angiotensin system exist in the ventrolateral medulla and they may modulate vasomotor outflow.