Biomedical subjects

P Constantinou

Publications and source records attributed to P Constantinou.

5 recordsLinked to original sources

PubMed2001

Molecular structure and activity toward DNA of baicalein, a flavone constituent of the Asian herbal medicine "Sho-saiko-to".

Baicalein (5,6,7-trihydroxyflavone, 1) is of interest because of its broad spectrum of biological activity. It is a constituent of the east Asian herbal remedy, "Sho-saiko-to". The 3D structure of 1 was determined using X-ray diffraction. The compound exists in an almost planar conformation with a C-2-C-1' bond distance of 1.476(5) A. Hydrogen-bonding interactions predominate in the crystal structure. The position of the three hydroxyl groups maximizes intramolecular hydrogen bonding, and each of the hydroxyl hydrogen atoms is a donor in a three-center hydrogen bond. The carbonyl oxygen, O-4, is an acceptor in an intramolecular hydrogen bond (with OH-5). Two molecules of 1 exist as hydrogen-bonded dimers related by inversion center (-x + 1, -y, -z + 1). O-4 is also an acceptor in an intermolecular hydrogen bond with OH-6. The planarity of the flavone framework is dependent on structural and/or electronic forces that stabilize the negative charge on the exocyclic oxygen atom, O-4. Compound 1, therefore, is planar in any situation where forces can stabilize the negative charge on O-4. Consistent with this, UV absorbance studies performed on 1-DNA complexes with varying concentrations of 1 strongly suggest intercalation of 1 within the double helix, followed by possible interstrand cross-links.

Animals↗

PubMed2001

Imaging of whole tumor cut sections using a novel scanning beam confocal fluorescence MACROscope.

Hypoxia caused by inadequate structure and function of the tumor vasculature has been found to negatively determine the prognosis of cancer patients. Hence, understanding the biological basis of tumor hypoxia is of significant clinical interest. To study solid tumor microenvironments in sufficient detail, large areas (several mm in diameter) need to be imaged at microm resolutions. We have used a novel confocal scanning laser MACROscope (CSLM) capable of acquiring images over fields of view up to 2cm x 2cm. To demonstrate its performance, frozen sections from a cervical carcinoma xenograft were triple labeled for tissue hypoxia, blood vessels and hypoxia-inducible transcription factor 1 alpha (HIF-1alpha), imaged using the CSLM and compared to images obtained using a standard epifluorescence microscope imaging system. The results indicate that the CSLM is a useful instrument for imaging tissue-based fluorescence at resolutions comparable to standard low-power microscope objectives.

Animals↗

PubMed1998

Low risk for tuberculosis in a regional pediatric hospital: nine-year study of community rates and the mandatory employee tuberculin skin-test program.

OBJECTIVE: To assess the risk of Mycobacterium tuberculosis infection and disease among patients and workers in a regional pediatric hospital. DESIGN: Descriptive epidemiological study of the mandatory tuberculin skin testing program of hospital employees at hire and during annual reevaluation, pediatric patients with tuberculosis (TB), efficacy of hospital infection control measures, and community rates of TB. SETTING: 361-bed, university, pediatric hospital serving Cincinnati (1.7 million population). RESULTS: During 1986 through 1994, 2,275 to 4,356 employees were compliant with Mantoux skin testing and screening each year. This represented >97% of the population who were eligible for screening. The cumulative rate of M tuberculosis infection from a previous positive tuberculin skin test was 10% to 12% per year during 1986 through 1994. Among new Mantoux skin-test converters in employees at annual reevaluation, the risk of TB infection was 0.3% in 1993 and 1994. There were no active cases of TB identified during new employee screening or annual reevaluation. Of 62 new Mantoux skin-test converters in 9 years, 23% were foreign-born, 13% were Asian, 23% were African American, 11% received the bacillus of Calmette-Guérin vaccine, and 60% had direct patient care or indirect patient contact. A cluster of five converters occurred in a department with no patient care or contact. Mantoux conversion rates were 1.9 per 1,000 employee patient-care or contact-years and 2.2 per 1,000 employee non-patient-contact years. Twenty pediatric patients with active TB were identified during 1991 to 1994, with < or =6 cases per year, placing this hospital in the low-risk category for M tuberculosis disease. Three children with pulmonary TB were admitted without immediate respiratory isolation, possibly exposing 9 patients and 42 employees; none converted their Mantoux skin tests on retesting. Rates of active TB in Cincinnati were stable during the period (eg, 8/100,000 population in 1994). CONCLUSIONS: Despite intense active surveillance among thousands of hospital employees with >97% annual compliance, tuberculin conversion rates were low, and no cases of active TB were identified during 9 years of follow-up. There was no evidence of transmission of M tuberculosis from infected patients to employees during uncontrolled exposures. Rates of TB in the community were low. These data suggest that rigorous application of the Centers for Disease Control and Prevention guidelines and Occupation Safety and Health Administration regulations for preventing nosocomial TB in pediatric hospitals may be excessive and costly. Special provisions should be made for pediatric hospitals with a proven low risk of transmission of M tuberculosis.

Adult↗

PubMed1995

The interactive image tool: adding structure to images.

The interactive image format and tool were developed by the Stanford University Medical Media and Information Technologies (SUMMIT) group to allow medical educators to add interactive annotations and outlines to medical cross-sections, gross dissections, and clinical images. The interactive image tool (IIT) format offers a general specification for adding structural information to images. The IIT format has been used to create rich databases of image/structure information which are employed in educational software created at SUMMIT. These databases consist of information which is re-usable in other applications as well as a standalone image database. Future extensions to the IIT format will provide a means to organize information based on the structure of that information rather than on the arbitrary or haphazard links of current hypertext and hypermedia information networks.

Anatomy↗

PubMed1994

Transforming information for computer-aided instruction: using a Socratic Dialogue method to teach gross anatomy.

Traditional teaching of anatomy can be a difficult process of rote memorization. Computers allow information presentation to be much more dynamic, and interactive; the same information can be presented in multiple organizations. Using this idea, we have implemented a new pedagogy for computer-assisted instruction in The Anatomy Lesson, an interactive digital teacher which uses a "Socratic Dialogue" metaphor, as well as a textbook-like approach, to facilitate conceptual learning in anatomy.

Anatomy↗