Mentoring, long recognized as a catalyst for successful careers, is particularly important to the career development of underrepresented minority (URM) faculty. In academic medicine, mentor-protégé relationships are seriously threatened by increased clinical, research, and administrative demands and an emphasis on scholarship over citizenship. New mentoring models are needed, and they should be adaptable to a medical school's unique structure and mission. The Peer-Onsite-Distance (POD) model, developed in 2002 by the authors and introduced at the College of Medicine at the University of Arkansas for Medical Sciences, is a targeted, multilevel mentoring prototype that is built on a solid research foundation and tailored to the unique needs of URM medical school faculty. The mentee's individual needs for guidance related to career goals, resources, and the content and interaction skills that are known to be critical to successful academic careers are targeted for development. The multilevel approach provides a unique network of peer and faculty mentors who provide site-specific career guidance. Also in the network are leaders in their fields who can provide access to accurate information, cautions, predictions, and announcements of future resources or potential restrictions in academic medicine. Mentor commitments are clearly defined and time contributions are maximized. The POD model aims to promote retention and advance the careers of URM faculty by wrapping them in a protective cushion of interpersonal and intrapersonal support. The flexibility of the design allows for adaptation to any institution's unique structure and mission.

A new metabolite of vitamin D3 was produced in vitro by perfusing rat kidneys with 1,25-dihydroxyvitamin D3 (4 X 10(-6) M). It was isolated and purified from the lipid extract of the kidney perfusate by high-performance liquid chromatography. By means of ultraviolet absorption spectrophotometry, mass spectrometry, chemical derivatization, and chemical synthesis, the new metabolite was identified as 1,23-dihydroxy-24,25,26,27-tetranorvitamin D3. Along with the new metabolite, three other previously identified metabolites, namely, 1,24,25-trihydroxyvitamin D3, 1,25-dihydroxy-24-oxovitamin D3, and 1,23,25-trihydroxy-24-oxovitamin D3, were also isolated. The new metabolite was also formed when 1,23,25-trihydroxy-24-oxovitamin D3 was used as the substrate. Thus, the new metabolite fits into the following metabolic pathway: 1,25-dihydroxyvitamin D3----1,24(R),25-trihydroxyvitamin D3----1,25-dihydroxy-24-oxovitamin D3----1,23,25-trihydroxy-24-oxovitamin D3----1,23-dihydroxy-24,25,26,27-tetranorvitamin D3. Further, we used 1 alpha,25-dihydroxy[1 beta-3H]vitamin D3 in the kidney perfusion system and demonstrated 1,23-dihydroxy-24,25,26,27-tetranorvitamin D3 as the major further metabolite of 1,25-dihydroxyvitamin D3, circulating in the final perfusate when kidneys were perfused with 1,25-dihydroxyvitamin D3 (6 X 10(-10) M) for 4 h. The biological activity of 1,23-dihydroxy-24,25,26,27-tetranorvitamin D3 (C-3 alcohol) and its metabolic relationship to 1-hydroxy-23-carboxy-24,25,26,27-tetranorvitamin D3 (calcitroic acid or C-23 acid), the other previously identified side-chain cleavage metabolite of 1,25-dihydroxyvitamin D3, are unknown and are presently undergoing investigation.

Current challenges to affirmative action policies are cause for concern for medical schools that employ holistic admissions processes, which consider an applicant’s race, ethnicity, gender, status as a first-generation college student, educational and socioeconomic status, geographical location, past experiences with minority and underserved populations, social capital, and immigration status. Students from minority and underserved communities bring with them experiences and perspectives that may enhance the care they provide to underserved patients, improving patient outcomes. Student body diversity is also associated with increases in students’ academic performance, retention, community engagement, cooperation, and openness to different ideas and perspectives, and institutions that foster diversity tend to be nurturing places where all students and faculty can thrive. The use of race as a factor in admissions has been upheld in three Supreme Court decisions. Yet, the Supreme Court likely will rule again on this issue. In the meantime, medical schools must maintain or increase support for science, technology, engineering, and math academic enrichment programs at all levels, stay informed about their institutional climate, and support a holistic admissions process that considers race and socioeconomic status. Doing so will help disadvantaged students overcome the intergenerational barriers created by race, ethnicity, and poverty and help grow a culturally competent health care workforce, which is essential to improving individual and population health and narrowing racial and ethnic health disparities.

Active receptors for Escherichia coli heat-stable enterotoxin (ST) were partially purified by ligand-affinity chromatography. The affinity column was prepared by coupling ST to biotin derivatized with an extended N-hydroxysuccinylated spacer arm prior to binding to monomeric avidin immobilized on agarose. Detergent extracts of rat intestinal mucosa membranes were quantitatively depleted of ST binding activity when chromatographed on this affinity matrix. Biotinylated ST-receptor complexes were eluted from affinity columns with 2 mM biotin and these complexes quantitatively dissociated with bile salts. Using this technique, functional ST receptors were purified maximally about 2000-fold, with about 3% of the total activity in crude extracts recovered in these purified preparations. Analysis of affinity-purified preparations by polyacrylamide gel electrophoresis and silver staining demonstrated a major protein subunit of 74 kDa. Affinity cross-linking of these preparations to 125I-ST demonstrated specific labeling predominantly of the 74-kDa subunit. In addition, lower amounts of labeled ST were incorporated into subunits of 164 and 45 kDa, confirming the heterogeneous nature of ST receptors. Purified receptors bound ST in a concentration-dependent fashion, with an IC50 of 10(-9) M. These studies demonstrate that ligand-affinity chromatography can be employed to purify ST receptors. The availability of purified receptors will facilitate further studies of mechanisms underlying ST-induced intestinal secretion.

Female Aedes aegypti that were fed blood and immediately abdominally ligated did not deposit yolk. Injection of 20-hydroxyecdysone (1.5-5.0 ng) or topical application of juvenile hormone (JH:I analogue methoprene (25 pg) did not induce vitellogenesis in these abdomens. When blood-gorged ligated abdomens were treated with both hormones, however, vitellogenesis was stimulated in 60% of treated animals. Rocket immunoelectrophoresis indicated that vitellin concentration per follicle in treated animals was similar to that in intact controls. When ligated abdomens were first treated with methoprene and immediately injected with a crude head extract of egg development neurosecretory hormone, vitellogenin synthesis was induced at a rate similar to that in blood-fed controls. blethoprene at this concentration (25 pg), did not cause an increase in whole-body ecdysteroid titers. Larger amounts of methoprene (1.65 ng) were needed to stimulate egg development and ecdysteroid production.Implantation of ecdysone-secreting ovaries into ligated abdomens did not stimulate vitellogenesis in the recipients. However, in recipients that were first treated with methoprene (25 pg), implantation of ecdysone-secreting ovaries resulted in normal egg development.These experiments indicate that the appearance of JH precedes 20-hydroxyecdysone in stimulating vitellogenesis following blood feeding in Ae. 76Borovsky et al Using high-pressure liquid chromatography, gas chromatography, and gas chromatography/mass spectrometry with chemical ionization, we isolated and identified JH Ill in a group of 2-to 10-h and 8-h blood-fed animals. Our data provide evidence that JH Ill (6.0 pg per female), which has been recently identified in larval and adult Ae. aegypti, is also present 8 h after a blood meal.