Characteristics of Helicobacter pylori natural transformation.

For Helicobacter pylori, which exhibits substantial genetic diversity, many strains are naturally competent for transformation by exogenous DNA. To better understand the mechanism of natural transformation and its role in the generation of diversity, we sought to systematically identify factors important for natural transformation in H. pylori. We now show that the highest frequency of H. pylori transformation occurs when DNA is introduced prior to exponential phase growth, and that it is a saturable phenomenon. That transformation can be inhibited by DNA from Helicobacter (H. pylori and Helicobacter bilis) but not Escherichia coli suggests specificity based on DNA source. Finally, the cag island was determined to be unnecessary for high-frequency transformation.

Clinical experience with a second-generation hospital-integrated picture archiving and communication system.

In a previous report we described a second-generation hospital-integrated picture archiving and communication system (HI-PACS) developed in-house. This HI-PACS had four unique features not found in other PAC systems. In this report, we will share some of our clinical experiences pertaining to these features during the past 12 months. We first describe the usage characteristics of two 2,000-line workstations (WSs), one in the in-patient and the second in the out-patient neuroradiology reading area. These two WSs can access neuro-images from 10 computed tomographic and magnetic resonance scanners located two medical centers through an asynchronous transfer mode network connection. The second unique feature of the system is an intensive care unit (ICU) server, which supports three WSs in the pediatric, medical surgery, and cardiac ICUs. The users' experiences and requests for refinement of the WSs are given. Another feature is physician desk-top access of PACS data. The HI-PACS provides a server connected to more than 100 Macintosh users for direct access of PACS data from their offices. The server's performance and user critiques are described. The last feature is a digital imaging and communication in medicine (DICOM) connection of the HI-PACS to a manufacturer's ultrasound PACS module. The authors then outline the interfacing process and summarize some of the difficulties encountered. Developing an in-house PACS has many advantages but also some drawbacks. Based on experience, the authors have formulated three axioms as a guide for in-house PACS development.