Conversion of L-phenylalanine to L-phenylglycine in the biosynthesis of virginiamycin S1 (1) can, in principle, take place with intramolecular nitrogen transfer or with intermolecular nitrogen transfer. A labeling experiment with DL-[3-13C, 15N]phenylalanine showed that the resulting L-phenylglycine contained no labeled nitrogen, indicating that the rearrangement proceeds via an intermolecular pathway.

Chemical Phenomena↗

PubMedDate not supplied

Coronary heart disease in African Americans.

African Americans have the highest overall mortality rate from coronary heart disease (CHD) of any ethnic group in the United States, particularly out-of-hospital deaths, and especially at younger ages. Although all of the reasons for the excess CHD mortality among African Americans have not been elucidated, it is clear that there is a high prevalence of certain coronary risk factors, delay in the recognition and treatment of high-risk individuals, and limited access to cardiovascular care. The clinical spectrum of acute and chronic CHD in African Americans is similar to that in whites. However, African Americans have a higher risk of sudden cardiac death and present more often with unstable angina and non-Q-wave myocardial infarction than whites. African Americans have less obstructive coronary artery disease on angiography, but may have a similar or greater total burden of coronary atherosclerosis. Ethnic differences in the clinical manifestations of CHD may be explained largely by the inherent heterogeneity of the coronary syndromes, and the disproportionately high prevalence and severity of hypertension and type 2 diabetes in African Americans. Identification of high-risk individuals for vigorous risk factor modification-especially control of hypertension, regression of left ventricular hypertrophy, control of diabetes, treatment of dyslipidemia, and smoking cessation--is key for successful risk reduction.

Age Factors↗

PubMedDate not supplied

Preeclampsia associated with chronic hypertension among African-American and White women.

OBJECTIVE: To examine the racial differences in preeclampsia/eclampsia (preeclampsia) associated with chronic hypertension among African-American and White women. METHODS: Using hospital discharge summary records from the National Hospital Discharge Survey from 1988 to 1996, we conducted a case-control study to assess the risk of preeclampsia among women with chronic hypertension in two separate identical models: one for African-American and another for White women. Cases were pregnant women who developed preeclampsia. Controls were women without preeclampsia. The main exposure was chronic hypertension. Logistic regression was used to derive odds ratios (OR) and 95% confidence intervals (CI) and to assess interaction between hypertension and preeclampsia. Population attributable risk percent associated between chronic hypertension and preeclampsia was calculated for each ethnic group. RESULTS: Preeclampsia was more than eleven times likely among women with chronic hypertension compared to normotensive women for both African-American (OR = 12.4, 95% CI = 10.2-15.2) and White women (OR = 11.3, 95% CI = 9.7-13.2). Among African-American women, we found an interaction between chronic hypertension and region on preeclampsia. The effect of region magnified the risk of preeclampsia associated with chronic hypertension in general for African-American women, but the effect was lower for the Southern region (OR = 8.9, 95% CI = 6.4-12.3). We also found that the point estimate of population attributable risk percent of preeclampsia attributable to chronic hypertension was significantly higher for African-American women (10.3, 95% CI = 8.6-12.5) compared to White women (5.3, 95% CI = 4.7-6.4). CONCLUSION: The more than eleven-fold higher risk of preeclampsia among both African-American and White women with chronic hypertension compared to normotensive women underscores the potential risk of chronic hypertension for adverse pregnancy outcomes. Furthermore, the two-fold higher population attributable risk percent of preeclampsia among African-American compared to White women quantifies the burden of preeclampsia attributable to chronic hypertension, and indicates a greater opportunity for prevention.

Adolescent↗

PubMedDate not supplied

Proceedings: The pattern of breathing in some pathological conditions of the cardiorespiratory system.

Explore the source record for details and available documents.

Humans↗

PubMedDate not supplied

Genetics of Aux/IAA and ARF action in plant growth and development.

Dramatic advances in our understanding of auxin signal-response pathways have been made in recent years. Much of this new knowledge has come through the study of mutants in Arabidopsis thaliana. Mutations have been identified in a wide variety of auxin-response components, including auxin transporters, protein kinases and phosphatases, components of a ubiquitin-proteosome pathway, and transcriptional regulators. This review focuses on mutations that affect auxin-modulated transcription factors, in particular those in the Aux/IAA and AUXIN RESPONSE FACTOR (ARF) genes. Mutants in members of these related gene families exhibit phenotypes that indicate both unique localized functions, as well as overlapping redundant functions, throughout plant development - from embryogenesis to flowering. Effects of specific mutations on Aux/IAA and ARF protein functions at the biochemical and physiological levels will be discussed. We will also discuss potential mechanisms for interactions between auxin and light response pathways that are suggested by these mutants.

Arabidopsis↗