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Biomedical subjects

D W Chen

Publications and source records attributed to D W Chen.

16 recordsLinked to original sources
PubMed2005

Synthesis, properties and microemulsion formulation of ibuprofen eugenol ester.

Ibuprofen-eugenol ester (IEE), a highly lipophilic compound, was synthesized from ibuprofen in order to reduce the common side effects induced by this classic anti-inflammatory drug. IEE was isolated as an amorphous whitish solid with a melting point at 40.2 +/- 0.1 degrees C, whose structure was confirmed by IR, 1H NMR and MS spectra. The hydrolysis results showed that the ester was stable over a wide pH range from 1.1-9.96. However, it could be hydrolyzed easily by enzymes from rat plasma and rat liver homogenate. A pharmaceutically acceptable microemulsion system was presented and characterized in terms of stability, droplet size distribution (DSD) and their solubilization capacity for IEE. The solubility of IEE in the optimized microemulsion formulation was about 21,000 times higher than that in water. The AUC of ibuprofen from the prodrug showed a remarkable increase compared to oral ibuprofen suspension. These results suggest that synthesizing the ibuprofen prodrug was justified and the presented microemulsion system might be a promising oral dosage form for poorly water-soluble drugs.

Animals↗
PubMed2001

Stereoselective synthesis of (Z)-enethiols and their derivatives: vinylic S(N)2 reaction of (E)-alkenyl(phenyl)-lambda3-iodanes with thioamides.

[reaction: see text]. Exposure of (E)-beta-alkylvinyl(phenyl)-lambda3-iodanes to thioamides in dichloromethane at room temperature was found to result in a bimolecular nucleophilic substitution (S(N)2) at the vinylic carbon atom to give inverted (Z)-enethiols and/or (Z)-S-vinylthioimidonium salts. Vinylic S(N)2 reactions with thioureas are also discussed.

Journal Article↗
PubMed2001

[3,3'-[2,2'-(ethylenedioxy)dibenzylidene]bis(S-methyl dithiocarbazate)]-nickel](II).

The tetradentate N(2)S(2) Schiff base ligand 3,3'-[2,2'-(ethylenedioxy)dibenzylidene]bis(S-methyl dithiocarbazate) (H(2)L), prepared by the condensation of S-methyl dithiocarbazate with 1,4-bis(2-formylphenyl)-1,4-dioxabutane in a 1:2 molar ratio, reacts with nickel acetate to form the title neutral metal complex, [Ni(C(20)H(20)N(4)O(2)S(4))]. The X-ray structure of the complex shows a distorted square-planar geometry around the Ni atom. The monomeric units are weakly associated into dimers via a long Ni.S interaction [3.569 (1) A]. These dimeric units are then linked by C-H.S intermolecular contacts to form a polymeric chain along the a axis.

Crystallography, X-Ray↗
PubMed2001

Preparation of stilbene-tethered nonnatural nucleosides for use with blue-fluorescent antibodies.

The synthesis of the first examples of stilbene-tethered hydrophobic C-nucleosides is described. Compounds of this type are targeted for use with our recently reported "blue-fluorescent antibodies" with the aim of probing native and nonnatural DNA. The nucleophilic addition of aryl Grignard reagents to either a protected 2'-deoxy-1'-chloro-ribofuranose or a protected 2'-deoxy-ribonolactone was the key synthetic step and afforded C-nucleosides in good yields. Both routes resulted in a final product that was >/=90% of the beta-anomer. Amide- and ether-based linkers for attachment of trans-stilbene to the nucleobase were assessed for utility during synthesis and in binding of the ligands to a blue-fluorescent monoclonal antibody. X-ray structures of each complex were obtained and serve as a guideline for second-generation stilbene-tethered C-nucleosides. The development of these hydrophobic nucleosides will be useful in current native and nonnatural DNA studies and invaluable for investigations regarding novel, nonnatural genomes in the future.

Antibodies↗
PubMed2001

[Study on the preparation of baicalin complex with phospholipid].

OBJECTIVE: To choose the optimization conditions for the formation of baicalin complex with phospholipid. METHOD: A reasonable criterion of accurate evaluation was established, by which such factors as temperature, the ratio of baicalin to phospholipid and the concentration of reactants were examined and the orthographic design was used. RESULT: The best conditions were obtained through statistical analysis and proof test. CONCLUSION: The formation of baicalin complex with phospholipid was greatly influenced by the solvent, concentration and reactant ratio.

Drug Carriers↗
PubMed2000

Prevention for the 21st century: setting the context through undergraduate medical education.

The generation of medical students now being taught will be practicing into the middle of the next century. They will be expected to provide an expanding array of clinical preventive services and be responsible for the health and well-being of entire populations and communities. Although prevention principles are being taught in many contexts, most medical schools do not have adequate curriculum-tracking systems that allow them to track the delivery of education and training in disease prevention and health promotion. The Bureau of Health Professions of the Health Resources and Services Administration (HRSA) and the Association of Teachers of Preventive Medicine have worked on several projects that have culminated in the development of a set of core competencies in preventive medicine for undergraduate medical education. In 1997 they convened a task force of medical educators from a broad array of basic science and clinical disciplines representing major U.S. medical teaching societies. The task force reviewed and updated the 1984 Inventory of Knowledge and Skills Relating to Disease Prevention and Health Promotion so that it would be relevant to faculty in diverse specialty areas and could be integrated throughout the medical curriculum. They then created a list of competencies that are essential from the perspective of each discipline and all disciplines. The article gives the context for teaching preventive medicine, presents the core competencies, and serves as the introduction to a supplement to Academic Medicine on teaching preventive medicine throughout the undergraduate medical curriculum.

Clinical Competence↗
PubMed1999

Core competencies for preventive medicine residents: Version 2.0.

During the early 1990s, the American College of Preventive Medicine (ACPM), with support from the Health Resources and Services Administration (HRSA), identified core competencies and performance indicators (measures to assess their achievement) for all preventive medicine residents. After the competencies were approved, distributed by the ACPM and HRSA, and published in the American Journal of Preventive Medicine, they were integrated in various ways into the operation of individual residency programs. Changes in the health care system during the decade, however, necessitated an update of the original competencies to better equip preventive medicine educators to prepare residents for new roles those in preventive medicine can play in a restructured health care system. HRSA funded an effort to produce Version 2.0 of the preventive medicine competencies based on review and refinement of the original competencies through a consensus process. This article includes these revised core competencies and performance indicators.

Clinical Competence↗
PubMed1998

History of federal legislation in health professions educational assistance in dental public health, 1956-97.

Health professions education assistance in dental public health has been congressionally authorized in one form or another during the last four decades. The US Department of Health and Human Services (and its predecessor, the Department of Health, Education, and Welfare) has been a focal point for managing these federal programs. This report tracks the history of relevant national legislation, beginning in the 1950s with the Health Amendment Acts of 1956 and continuing most recently with the Health Professions Education Extension Amendments of 1992. The number of dental public health professionals trained and available to provide expertise and leadership to improve community oral health status has been tied to the presence and intensity of federal programming in this area.

Education, Dental, Graduate↗
PubMed1998

Filling the gap: equity and access to oral health services for minorities and the underserved.

BACKGROUND AND OBJECTIVES: Family physicians and other primary care providers play a pivotal role in preventing oral disease, especially among minority and underserved populations who have limited access to dental services and poorer oral health status. Oral diseases/conditions, such as caries, baby bottle tooth decay, gingivitis, periodontitis, oral pharyngeal malignancies, and orofacial trauma, are prevalent and costly, yet largely preventable. Given their role in promoting and protecting overall health and their historical role in serving minority and underserved families, family physicians occupy a unique position to assure equity, access, and improvement in oral health for all Americans.

Adolescent↗
PubMed1996

Population-based medical education: linkages between schools of medicine and public health agencies.

PURPOSE: To examine the educational linkages between medical schools and public health agencies (PHAs); characterize programs for medical student placement at PHAs; explore attitudes toward using PHAs as student teaching sites; and investigate factors that facilitate or hinder such placements. METHOD: A 20-item questionnaire was mailed in the summer of 1994 to all 134 allopathic medical schools in the United States (for schools with more than one campus, each campus was counted as a separate school). The chi-square and Mann-Whitney U tests were used to assess associations between variables. RESULTS: A total of 108 schools (81%) responded. Of these, 68 (63%) reported having a program that places some or all students at PHAs. The most common facilitating factors were proximity of PHA(s) (84%), faculty interest in public health (76%), support of the PHA director and personnel (67%), and faculty appointments for public health personnel (63%). Two barriers differentiated schools having a PHA placement program from those not having one: lack of faculty interest (p = .001) and lack of a designated PHA contact person (p = .002). CONCLUSION: An unexpectedly large number of schools placed students in PHAs to receive training. However, medical schools are not utilizing the full potential of PHAs as teaching sites.

Clinical Clerkship↗
PubMed1994

Substituted phthalocyanine-sensitized photochemical generation of superoxide anion radical.

The quantum yield of phthalocyanine-photosensitized generation of superoxide anion radical (O2-) was measured by the electron spin resonance (ESR) technique. From the redox potential data, it is concluded that O2- is formed by electron transfer from the singlet excited state (not triplet or ground state) of phthalocyanines (PCs) to oxygen. Since a much larger theoretical quantum yield of O2- generation (phi c) than experimental (phi m) was found, it is suggested that charge recombination processes between O2- and PCs+ occur more rapidly than O2- trapping by 5,5-dimethyl-1-pyrroline-1-oxide (DMPO). The results indicate that the use of DMPO as a spin trap is not an ideal method for measurement of the quantity of O2- formed via photosensitization.

Cyclic N-Oxides↗
PubMed1988

AIDS -- a modern hydra.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Infant mortality increase despite high access to tertiary care: an evolving relationship among infant mortality, health care, and socioeconomic change.

In this study, the determinants of an apparent increase in the infant mortality rate of an urban population with high access to tertiary neonatal care are reviewed. For a 4-year period (1980 to 1983), all infant deaths (n = 422) of the 32,329 births to residents of the City of Boston were analyzed through linked vital statistics data and a review of medical records. A significant increase in the infant mortality rate occurred in 1982 due to increases in three components of the infant mortality rate: the birth rate of very low birth weight infants (less than 1,500 g), the neonatal mortality rate of normal birth weight infants (greater than or equal to 2,500 g), and the mortality rate of infants dying during the postneonatal period (28 to 365 days). These increases were associated with inadequate levels of prenatal care. Although transient, the impact of the observed alterations in these infant mortality rate components was enhanced by a more long-standing phenomenon: the stabilization of mortality rates for low birth weight infants. This stabilization allowed the increases in other component rates to be expressed more fully than in previous years. In this report a mechanism is shown whereby fully regionalized neonatal care ultimately may confer to the infant mortality rate a heightened sensitivity to socioeconomic conditions and levels of adequate prenatal care.

Birth Rate↗
PubMedDate not supplied

Public health workforce enumeration: beware the "quick fix".

The most common source of information on workforce in the United States is the Bureau of Labor Statistics (BLS), a branch of the Department of Labor. In 1998, 14 public health workforce titles were added to the BLS Standard Occupational Classification (SOC) system. While this was a constructive step, it is not a "quick fix," because these additional titles do not solve the longstanding problems inherent in capturing accurate PH workforce data. As is true for all currently available sources, BLS statistics capture a limited segment of public health's broadly defined and multidisciplinary workforce. A standard system of data collection is needed to guide planning to sustain the present and future workforce. Revision of the 1998 SOC in preparation for the 2010 Census is now underway. This presents an opportunity for the public health community to act on prior recommendations regarding workforce data and advocate for more inclusive enumeration of public health occupations that can inform policies and planning for the current and future workforce.

Employment↗
PubMedDate not supplied

Performance indicators for assessing competencies of preventive medicine residents.

Heightened national interest in population-based medicine, clinical preventive services, and health care management underscores the current need for definition and assessment of physician competency in these areas. This article describes a project sponsored by the Health Resources and Services Administration (HRSA) to develop competencies for each of the three specialty areas in preventive medicine and appropriate measures for the achievement of those competencies. We discuss fundamental issues surrounding assessment that helped guide the process, types of measurement strategies, and criteria for effective competencies and performance indicators. The article also explains the Work Group process used to reach consensus and identifies concerns and challenges raised during this process. We include the list of specialty competencies and performance indicators developed by the project. The project, entitled "Improving Training of Preventive Medicine Residents through the Development and Evaluation of Competencies," served as a model for interorganizational collaboration between the federal government (HRSA); a specialty society, the American College of Preventive Medicine (ACPM); and a preventive medicine residency program, State University of New York (SUNY) at Stony Brook. The commonality of competencies expected of residents in all three specialty areas of preventive medicine--occupational medicine, general preventive medicine and public health, and aerospace medicine--reaffirmed the rationale for including all of these areas within the single specialty of preventive medicine.

Aerospace Medicine↗