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Biomedical subjects

R C Morgan

Publications and source records attributed to R C Morgan.

At least 19 recordsLinked to original sources
PubMed2001

Impact of anti-affirmative action on medical school enrollment.

The nation's medical, dental and health profession school admissions of African American and other under-represented minority students needs reassessment in view of recent challenges to anti-affirmative action policies. Data suggest that low-income and medically underserved communities are more likely to be cared for by minority physicians. Experts project that the U.S. will need about twice as many African-American physicians as it now has to serve future patient needs. Currently, African Americans comprise 3% of the physician workforce. Decisive actions and policies--such as the recommendations made by the National Medical Association--are needed to ensure parity and cultural diversity in the medical workforce.

Adult↗
PubMed1998

Mirasorvone: a masked 20-ketopregnane from the defensive secretion of a diving beetle (Thermonectus marmoratus).

The sunburst diving beetle, Thermonectus marmoratus, ejects a milky fluid from its prothoracic defensive glands when disturbed. Two major volatile components of this secretion are steroids; cybisterone (structure 7) constitutes about 20% of the volatiles, and a new steroid, mirasorvone, about 50%. Mirasorvone is assigned an 18-oxygenated pregnane structure (structure 9) on the basis of extensive spectroscopic data. Although no 18-oxygenated steroid has been described previously from an insect source, a closely related hormone with mineralocorticoid activity, 18-hydroxydeoxycorticosterone (structure 13), has been isolated from the adrenal glands of rats.

Animals↗
PubMed1997

Defensive production of quinoline by a phasmid insect (Oreophoetes peruana).

Adults and nymphs of the Peruvian stick insect Oreophoetes peruana (order Phasmatodea) have a pair of thoracic glands from which they discharge a malodorous fluid when disturbed. The secretion contains a single volatile component, quinoline. Quinoline has not been reported previously from an animal source. The compound proved repellent or topically irritant in assays with ants, spiders, cockroaches and frogs. O. peruana nymphs, at molting, do not extricate the shed cuticular lining of the glands, thereby managing not to lose their secretory supply when they cast their skin. They are able, as a consequence, to discharge secretion even while still teneral after molting.

Animals↗
PubMed1997

Society's search for a legal and ethical basis of physician-assisted suicide.

A review of the way physician-assisted suicide (PAS) is being addressed in the United States reveals three models, each functioning out of distinctive concepts of autonomy: (1) litigation, which utilizes philosophical autonomy; (2) legislation, which utilizes political autonomy; and (3) act of conscience by a physician, which utilizes consumer autonomy. Each model raises a correspondingly distinct set of ethical questions and challenges centered around their point of reference-the judicial system, voters, or the doctor-patient relationship. In the end, however, efforts to resolve the challenge of PAS will falter if they do not go beyond these models of autonomy. Religious institutions offer a more constructive setting for facing the life and death decisionmaking of PAS. The challenge for religion is to address PAS in solidarity with sufferers, physicians, and the community, rather than retreating into iconoclastic dogmas.

Aged↗
PubMed1992

Removal of viscoelastic materials after experimental cataract surgery in vitro.

The one significant complication of viscoelastic materials is that they may cause postoperative intraocular pressure rise. We investigated the rate and ease of removal of various viscoelastics using the Miyake video technique. Five viscoelastics were investigated: sodium hyaluronate (Healon), Healon GV, chondroitin sulfatesodium hyaluronate (Viscoat), hydroxypropylmethylcellulose (Occucoat), and polyacrylamide (Orcolon). The viscoelastics were dyed with fluorescein and, after filling the capsular bag with a viscoelastic material, a posterior chamber intraocular lens (IOL) was implanted. The viscoelastic was then aspirated using an automated irrigation/aspiration device. Healon and Healon GV were completely removed within 20 to 25 seconds. Viscoat adhered to the lens capsule and to the posterior surface of the IOL and cooplete removal required approximately 3.5 minutes. Most Occucoat and Orcolon was aspirated within one minute; however, removal was completed only after three minutes. Removal of Healon and Healon GV was faster and more complete than removal of the other viscoelastics. Whether a small amount of viscoelastic left in the eye or trapped behind the IOL optic has any clinical significance has to be studied.

Acrylic Resins↗
PubMed1991

Mechanism of radial tear formation and extension after anterior capsulectomy.

The mechanisms of anterior capsular radial tear formation and extension around the equator onto the posterior capsule were investigated in 57 eyes obtained postmortem. Experimental radial tears were created by gradual opening of a caliper. In 95% of cases, the tear immediately reached the equator but none extended to the posterior capsule. The elastic forces of the zonules attached to or crossing the edges of the tear resisted a widening of the gap between the edges and thus limited the radial progression of the rupture. A significantly stronger force and severing of the zonules were necessary for a tear to extend around the equator. The authors have determined that radial tears in the anterior capsule seldom extend around the equator, providing the zonules bridging the tear are intact. There is a diminution of the tearing force when the flaps are widely open. Careful surgery with preservation of the integrity of the capsular-zonular apparatus is a major factor in preventing major complications such as posterior capsular ruptures.

Aged↗