Is a Career in Medicine the Right Choice? The Impact of a Physician Shadowing Program on Undergraduate Premedical Students.
Academic medicine : journal of the Association of American Medical Colleges
Undergraduate (i.e., baccalaureate) premedical students have limited exposure to clinical practice before applying to medical school-a shortcoming, given the personal and financial resources required to complete medical training.The Stanford Immersion in Medicine Series (SIMS) is a program that streamlines the completion of regulatory requirements for premedical students and allows them to develop one-on-one mentor-mentee relationships with practicing physicians. The program, offered quarterly since 2007, is an elective available for Stanford University sophomores, juniors, and seniors. Participants apply to the program and, if accepted, receive patient rights and professionalism training. Students shadow the physician they are paired with at least four times and submit a reflective essay about their experience.SIMS program coordinators administered surveys before and after shadowing to assess changes in students' perceptions and understanding of medical careers.The authors observed, in the 61 Stanford premedical students who participated in SIMS between March and June 2010 and completed both pre- and postprogram questionnaires, significant increases in familiarity with physician responsibilities and in understanding physician-patient interactions. The authors detected no significant changes in student commitment to pursuing medicine. Student perceptions of the value of shadowing-high both pre- and post shadowing-did not change.Physician shadowing by premedical baccalaureate students appears to promote an understanding of physician roles and workplace challenges. Future studies should identify the ideal timing, format, and duration of shadowing to optimize the experience and allow students to make informed decisions about whether to pursue a medical career.
View details for DOI 10.1097/ACM.0000000000000615
View details for PubMedID 25565263
Combination of calcitriol and dietary soy exhibits enhanced anticancer activity and increased hypercalcemic toxicity in a mouse xenograft model of prostate cancer
2012; 72 (15): 1628-1637
The potential role of vitamin D and soy in prostate cancer (PCa) prevention/treatment has gained much attention in recent years. In this study, we evaluated the anticancer activity of calcitriol, the active form of vitamin D, dietary soy, and their combinations in a mouse model of PCa.Athymic male nude mice bearing PC-3 human PCa xenografts received diets containing 10 or 20 kcal% soy, calcitriol injections, or a combination of dietary soy and calcitriol. Changes in tumor growth, serum levels of 1,25(OH)(2)D and calcium, and regulation of tumor gene expression were examined.The combination treatments resulted in substantially greater inhibition of tumor growth than either agent alone. Soy diets alone caused a modest elevation in serum 1,25(OH)(2)D, whereas the calcitriol-soy combinations led to substantially elevated serum 1,25(OH)(2) D, hypercalcemia, and in some cases lethal toxicity. The combinations enhanced calcitriol activity in regulating target gene expression, including greater up-regulation of anti-proliferative (p21, IGFBP-3) and pro-apoptotic (Bax) genes, increased inhibition of anti-apoptotic (Bcl-2) and cell cycle promoting (cyclin D1) genes, and suppression of prostaglandin (PG) synthesis and signaling (COX-2, 15-PGDH, PG receptors). Increases in serum calcium were accompanied by elevated expression of intestinal calcium absorption genes (TRPV6, calbindin-9k).Soy increases the bioavailability of endogenous and administered calcitriol, thereby enhancing its anticancer effects and risk of hypercalcemia. Since both agents are easily available as dietary supplements, the increased potential for hypercalcemic toxicity becomes an important factor when considering the combined use of vitamin D and soy in PCa therapy.
View details for DOI 10.1002/pros.22516
View details for Web of Science ID 000309405800004
View details for PubMedID 22457201
Dietary Vitamin D-3 and 1,25-Dihydroxyvitamin D-3 (Calcitriol) Exhibit Equivalent Anticancer Activity in Mouse Xenograft Models of Breast and Prostate Cancer
2012; 153 (6): 2576-2587
1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3) or calcitriol], the hormonally active vitamin D metabolite, exhibits anticancer actions in models of breast cancer and prostate cancer. Because CYP27B1 (1?-hydroxylase), the enzyme catalyzing 1,25(OH)(2)D(3) formation in the kidney, is also expressed in extrarenal tissues, we hypothesize that dietary vitamin D(3) will be converted to 25(OH)D(3) in the body and then to 1,25(OH)(2)D(3) locally in the cancer microenvironment in which it will exert autocrine/paracrine anticancer actions. Immunocompromised mice bearing MCF-7 breast cancer xenografts showed significant tumor shrinkage (>50%) after ingestion of a vitamin D(3)-supplemented diet (5000 IU/kg) compared with a control diet (1000 IU/kg). Dietary vitamin D(3) inhibition of tumor growth was equivalent to administered calcitriol (0.025, 0.05, or 0.1 ?g/mouse, three times a week). Both treatments equivalently inhibited PC-3 prostate cancer xenograft growth but to a lesser extent than the MCF-7 tumors. Calcitriol at 0.05 ?g and 0.1 ?g caused modest but statistically significant increases in serum calcium levels indicating that the dietary vitamin D(3) comparison was to a maximally safe calcitriol dose. Dietary vitamin D(3) did not increase serum calcium, demonstrating its safety at the concentration tested. The vitamin D(3) diet raised circulating 1,25 dihydroxyvitamin D levels and did not alter CYP27B1 mRNA in the kidney but increased it in the tumors, suggesting that extrarenal sources including the tumors contributed to the elevated circulating 1,25 dihydroxyvitamin D(3). Both calcitriol and dietary vitamin D(3) were equipotent in suppressing estrogen synthesis and signaling and other proinflammatory and growth signaling pathways. These preclinical data demonstrate the potential utility of dietary vitamin D(3) supplementation in cancer prevention and therapy.
View details for DOI 10.1210/en.2011-1600
View details for Web of Science ID 000304370700010
View details for PubMedID 22454149
Inhibitory effects of calcitriol on the growth of MCF-7 breast cancer xenografts in nude mice: selective modulation of aromatase expression in vivo.
Hormones & cancer
2011; 2 (3): 190-202
Calcitriol (1,25-dihydroxyvitamin D(3)), the hormonally active metabolite of vitamin D, exerts many anticancer effects in breast cancer (BCa) cells. We have previously shown using cell culture models that calcitriol acts as a selective aromatase modulator (SAM) and inhibits estrogen synthesis and signaling in BCa cells. We have now examined calcitriol effects in vivo on aromatase expression, estrogen signaling, and tumor growth when used alone and in combination with aromatase inhibitors (AIs). In immunocompromised mice bearing MCF-7 xenografts, increasing doses of calcitriol exhibited significant tumor inhibitory effects (~50% to 70% decrease in tumor volume). At the suboptimal doses tested, anastrozole and letrozole also caused significant tumor shrinkage when used individually. Although the combinations of calcitriol and the AIs caused a statistically significant increase in tumor inhibition in comparison to the single agents, the cooperative interaction between these agents appeared to be minimal at the doses tested. Calcitriol decreased aromatase expression in the xenograft tumors. Importantly, calcitriol also acted as a SAM in the mouse, decreasing aromatase expression in the mammary adipose tissue, while increasing it in bone marrow cells and not altering it in the ovaries and uteri. As a result, calcitriol significantly reduced estrogen levels in the xenograft tumors and surrounding breast adipose tissue. In addition, calcitriol inhibited estrogen signaling by decreasing tumor ER? levels. Changes in tumor gene expression revealed the suppressive effects of calcitriol on inflammatory and growth signaling pathways and demonstrated cooperative interactions between calcitriol and AIs to modulate gene expression. We hypothesize that cumulatively these calcitriol actions would contribute to a beneficial effect when calcitriol is combined with an AI in the treatment of BCa.
View details for DOI 10.1007/s12672-011-0073-7
View details for PubMedID 21686077