MicroRNA-29a regulates intestinal membrane permeability in patients with irritable bowel syndrome.

BACKGROUND: The molecular mechanisms underlying the pathophysiology of irritable bowel syndrome (IBS) are poorly understood. One mechanism may involve increased intestinal permeability that is reversed with glutamine supplementation. Our goal was to evaluate the expression of glutamine synthetase and its complementary miRNA in blood microvesicles and gut tissues of IBS patients with increased intestinal membrane permeability. METHODS: We evaluated 19 diarrhoea-predominant IBS patients and 10 controls for intestinal membrane permeability using the lactulose/mannitol method. miRNA expression was evaluated in blood microvesicles and gut tissue. To further confirm the relationship between miRNA and glutamine synthetase expression, cell culture experiments were conducted. Glutamine synthetase was also evaluated in the gut tissues of patients. RESULTS: A subset of patients with IBS (8/19, 42%) had increased intestinal membrane permeability and decreased glutamine synthetase expression compared to patients with IBS normal membrane permeability, and to controls. Expression of miR-29a was increased in blood microvesicles, small bowel and colon tissues of IBS patients with increased intestinal membrane permeability. Increased intestinal permeability was modulated by miR-29a which has a complementary site in the 3'-UTR of the GLUL gene. CONCLUSIONS: The results support the conclusion that GLUL regulates intestinal membrane permeability and miR-29a regulates both GLUL and intestinal membrane permeability. The data suggests that miR-29a effects on intestinal membrane permeability may be due to its regulation of GLUL. Targeting this signalling pathway could lead to a new therapeutic approach to the treatment of patients with IBS, especially because small molecules that mimic or inhibit miRNA-based mechanisms are readily available.

Does agreement on institutional values and leadership issues between deans and surgery chairs predict their institutions' performance?

PURPOSE: To gain a better understanding of the values that medical school deans and surgery chairs consider most essential for effective leadership, to assess their perceptions of the values and leadership climate in their institutions, and to test the premise that agreement on leadership values and climate predict greater organizational effectiveness and performance. METHOD: From June 2005 through March 2006, questionnaires designed to assess leadership core values and organizational leadership climate were mailed to medical school deans and surgery chairs of the 125 U.S. academic health centers. Institutional performance measures used were the National Institutes of Health (NIH) standing and U.S. News and World Report ranking of each institution. RESULTS: Sixty-eight surgery chairs (54%) and 60 deans (48%) returned surveys. Q-sort results on 38 positive leadership values indicated that integrity, trust, and vision were considered the most important core values for effective leadership by both chairs and deans. Both groups ranked business acumen, authority, and institutional reputation as least important. Deans consistently ranked the leadership climate as being healthier (more positive) than did their surgery chairs on multiple scale items: leadership is widely shared (P = .005), information is widely shared (P = .002), missions are aligned (P = .003), open communication is the norm (P = .009), good performance is rewarded (P = .01), teamwork is widely practiced (P = .01), and leaders are held accountable (P = 002). Tighter alignment between chairs and deans on core values and on the leadership climate scale correlated with higher school and department NIH standing and higher U.S. News and World Report medical school and hospital ranking (P < .05). CONCLUSIONS: Although surgery chairs and deans espouse similar core leadership values, deans believe that a healthier leadership climate exists in their institutions than their surgery chairs do. The study findings suggest that tighter leadership alignment between deans and surgery chairs may predict a higher level of institutional performance in the clinical and academic arenas.

Leadership values in academic medicine.

PURPOSE: To gain a deeper understanding of the guiding core values that deans of academic medical centers (AMCs) considered most essential for their leadership and the major leadership challenges that confront them. METHOD: In 2003-04, semistructured interviews of 18 deans at U.S. colleges of medicine or AMCs were organized around four dimensions: background, leadership challenges, organizational effectiveness, and systems enablers/restrainers for leadership. A values Q-sort was used to determine how widely core values were shared among deans and how the complex challenges they faced did or did not align with these values. RESULTS: Fourteen of the 18 (78%) deans identified financial difficulties as their most pressing leadership challenge, followed by weak institutional alignment (61%), staffing problems (33%), and poor morale (28%). Open, candid communication was reported as the most effective means of addressing these complex problems. Enacting espoused shared values and having a positive attitude were identified as the most important enablers of systemic leadership, whereas micromanagement and difficult people were the major restraints. Q-sort results on 38 positive leadership values indicated that participants considered integrity most essential. Integrity was positively correlated with humanistic values and negatively correlated with results. Vision, another highly espoused value, correlated strongly with performance-oriented values but correlated negatively with humanistic values. CONCLUSIONS: A dynamic tension exists in AMCs between humanistic values and performance-based core values. The ability to manage that tension (i.e., when to prioritize one set of values over the other) is inherent in a dean's work.

Regulation of amino acid arginine transport by lipopolysaccharide and nitric oxide in intestinal epithelial IEC-6 cells.

As a precursor for nitric oxide (NO) synthesis and an immune-enhancing nutrient, amino acid L-arginine plays a critical role in maintaining intestine mucosal integrity and immune functions in sepsis. However, the relationship between intestinal arginine transport and NO synthesis in sepsis remains unclear. In the present study, we investigated the effects of lipopolysaccharide (LPS) and NO on the arginine transport in cultured rat intestinal epithelial IEC-6 cell. Near-confluent IEC-6 cells were incubated with LPS (0-50 microg/ml) in serum-free Dulbecco's modified Eagles's medium, in the presence and absence of the NO donor sodium nitroprusside (SNP, 0-500 micromol/L) and the inducible nitric oxide synthase (iNOS) inhibitor N-omega-nitro-L-arginine (NNA, 0-1000 micromol/L) for various periods of time (0-48 hours). Arginine transport activity, arginine transporter CAT1 mRNA and protein levels were measured with transport assay, Northern blot analysis, and Western blot analysis, respectively. LPS increased arginine transport activity in a time- and dose-dependent fashion. Prolonged incubation of LPS (24 hours, 25 microg/ml) resulted in a 3-fold increase of arginine transport activity (control: 28 +/- 5; LPS: 92 +/- 20 pmol/mg/min, P < 0.05), with the System y(+) as the predominant arginine transport system, and a 2-fold increase of System y(+)CAT1 mRNA and transporter protein levels (P < 0.05). LPS increased the arginine transport System y(+) maximal velocity (V(max), control: 1484 +/- 180; LPS: 2800 +/- 230 pmol/mg/min, P < 0.05) without affecting the transport affinity (K(m), control: 76 +/- 8; LPS: 84 +/- 14 micromol/L, p = NS). The LPS-induced arginine transport activity was blocked by sodium nitroprusside (SNP) (control: 25 +/- 6; LPS: 97 +/- 26 *; SNP: 22 +/- 0.4(+); LPS+SNP: 33 +/- 10.3(+) pmole/mg/min, *P < 0.01 and (+)p = NS, compared with control). In contrary, the LPS-induced arginine transport activity was further augmented by NNA (control: 18 +/- 3.2; LPS: 59 +/- 2.7 *; NNA: 26.3 +/- 5.8; LPS + NNA: 127 +/- 18(+) pmol/mg/min; *P < 0.01 compared with control and (+)P < 0.01 compared with control or LPS). LPS-stimulates arginine transport activity in IEC-6 cells via a mechanism that involves increase of transport System y(+) mRNA levels and transporter protein levels. The LPS-stimulated arginine transport activity is regulated by the availability of nitric oxide.

Reinventing the academic health center.

Academic health centers have faced well-documented internal and external challenges over the last decade, putting pressure on organizational leaders to develop new strategies to improve performance while simultaneously addressing employee morale, patient satisfaction, educational outcomes, and research growth. In the aftermath of a failed merger, new leaders of The Pennsylvania State University College of Medicine and Milton S. Hershey Medical Center encountered a climate of readiness for a transformational change. In a case study of this process, nine critical success factors are described that contributed to significant performance improvement: performing a campus-wide cultural assessment and acting decisively on the results; making values explicit and active in everyday decisions; aligning corporate structure and governance to unify the academic enterprise and health system; aligning the next tier of administrative structure and function; fostering collaboration and accountability-the creation of unified campus teams; articulating a succinct, highly focused, and compelling vision and strategic plan; using the tools of mission-based management to realign resources; focusing leadership recruitment on organizational fit; and "growing your own" through broad-based leadership development. Outcomes assessment data for academic, research, and clinical performance showed significant gains between 2000 and 2004. Organizational transformation as a result of the nine factors is possible in other institutional settings and can facilitate a focus on crucial quality initiatives.

Stimulation of intestinal glutamine absorption in chronic metabolic acidosis.

BACKGROUND: Amino acid glutamine plays a central role in inter-organ nitrogen transfer in acidosis, a compensatory mechanism that is essential in maintaining acidbase balance. Intestinal glutamine absorption is a key exogenous glutamine source in maintaining glutamine homeostasis. The purpose of this in vivo study was to investigate the regulation of intestinal glutamine absorption during chronic metabolic acidosis. METHODS: Metabolic acidosis in adult male Sprague-Dawley rats was induced by adding 1.5% NH4Cl to drinking water. [3H]-L-glutamine transport activity across brush border membrane vesicles and glutamine transporter ATB0 messenger RNA levels by relative reverse transcriptase-polymerase chain reaction were measured in rat jejunum. Data were analyzed by t test (P < .05). RESULTS: Acidosis occurred as early as 1 day and was partially compensated by 7 days. Glutamine transport in brush border membrane vesicles was increased after 2 days of acidosis. Chronic acidosis (7 days) resulted in an 8-fold increase of glutamine transport activity. The glutamine transport maximal capacity (Vmax) was stimulated 5-fold, while the transport affinity (Km) was not affected by acidosis. Relative reverse transcriptase-polymerase chain reaction showed a 2.5-fold increase of glutamine transporter ATB0 messenger RNA levels. CONCLUSIONS: Chronic metabolic acidosis stimulates intestinal glutamine absorption via a mechanism that involves an increase of functional membrane glutamine transporter units.

Specific reversible stimulation of system y(+) L-arginine transport activity in human intestinal cells.

L-Arginine, which is intimately involved in cellular immune functions and nitric oxide biology, is transported by intestinal cells largely via transport System y(+). The gut epithelium is exposed to various luminal amino acids at any given time, and therefore the purpose of this study was to study the regulation of luminal arginine transport by other amino acids. System y(+) L-arginine transport activity was measured in Caco-2 monolayers exposed to various amino acids. L-arginine and/or other System y(+) substrates specifically upregulated System y(+) transport activity twofold after 1 hour, with a response noted as early as 5 minutes. Non-System y(+) substrates did not affect L-arginine absorption. Kinetic analysis indicated that L-arginine exposure increased both System y(+) K(m) and V(max). Neither cycloheximide nor actinomycin affected this stimulation, indicating that the regulation did not involve transcription or translation. The System y(+) substrate activation effect was reversible. L-arginine transport activity returned to baseline within 3 hours when cells were reincubated in amino acid-free media. These data indicate that System y(+) arginine transport activity is rapidly and reversibly activated by System y(+) substrates via a mechanism consistent with transmembrane stimulation. These findings identify a mechanism by which luminal nutrients regulate arginine uptake by the gut.

Epidermal growth factor regulation of system L alanine transport in undifferentiated and differentiated intestinal Caco-2 cells.

Epidermal growth factor (EGF) in intestinal lumen regulates many gut epithelial cell functions. Influenced by growth factors at various differentiation stages, enterocytes execute the major task of absorbing nutrient amino acids. The purpose of this study was to investigate the effects of EGF on Na(+)-independent L-alanine transport in intestinal epithelial cells. Na(+)-independent [3H]-L-alanine transport was measured in the differentiating Caco-2 cells. In both the undifferentiated and differentiated states, L-alanine uptake occurred via a single saturable Na(+)-independent system L plus simple passive diffusion. System L activity decreased as the cells progressed from the undifferentiated to the differentiated state. Prolonged incubation with EGF (>30 hours) resulted in a 70% increase in system L activity in both undifferentiated and differentiated cells. EGF stimulated the system L V(max) without affecting K(m). System L activity stimulation was inhibited by chelerythrine chloride, cycloheximide, or actinomycin D. These data suggest that intestinal epithelial cell differentiation is associated with a decrease in system L transport capacity. EGF activates system L transport activity through a signaling mechanism involving protein kinase C, independent of cell differentiation state. Both cell differentiation and EGF regulation of system L activity occur via alteration of functional copies of the system L transporter.

Activation of intestinal arginine transport by protein kinase C is mediated by mitogen-activated protein kinases.

L-Arginine uptake by the small intestine can play a pivotal role in regulating nitric oxide synthesis and immune functions in catabolic states. We previously showed that protein kinase C (PKC) activation stimulates intestinal brush-border membrane arginine transport. However, the signaling pathways implicated in this activation have not been studied. The purpose of this study was to investigate the intracellular signal transduction pathways involved in the protein kinase C stimulation of arginine transport across the apical membrane of intestinal epithelial Caco-2 cells. [3H]-L-arginine transport activity, Northern blot analysis of mRNA levels of the intestinal arginine transporter CAT1, and Western blot analysis of the mitogen-activated protein (MAP) kinases phospho-p44/42 activity and phospho-MEK1/2 were measured in cultured Caco-2 cells treated with phorbol ester (phorbol 12-myristate 13-acetate, TPA; 0 to 0.5 micromol/L), and the MEK1 inhibitor PD 98059 (0 to 50 micromol/L). Phorbol ester stimulated intestinal arginine transport activity. Arginine transporter gene CAT1 mRNA, phospho-p44/42, and phospho-MEK1/2 levels were stimulated in phorbol ester-treated cells, compared with the control group. Phorbol ester stimulation of arginine transport activity and transporter CAT1 mRNA levels was blocked by PD 98059. These data suggest that phorbol ester stimulates arginine transport in Caco-2 cells via signaling pathways that lead to increased transcription and/or stabilization of CAT1 mRNA. Protein kinase C and MAP kinases MEK1/2 and p44/42 are key intracellular regulators involved in this signal transduction cascade.

Metabolic acidosis stimulates intestinal glutamine absorption.

Glutamine is an essential nutrient for cell integrity during acidotic states such as shock, but the effect of extracellular pH on intestinal mucosal cell glutamine uptake is poorly understood. The purpose of this in vitro study was to investigate the intracellular signaling pathways involved in controlling intestinal glutamine transport during acidosis. Lowering the pH in the cell culture medium resulted in an increase in glutamine transport activity in a time- and pH-dependent fashion. Chronic acidosis (pH 6.6 for 48 hours) resulted in a twofold increase in glutamine transport activity (1.63+/-0.25 nmole/mg protein/minute in acidosis vs. 0.78+/-0.11 nmole/mg protein/minute in control) and a threefold increase in glutamine transport gene ATB(0) messenger RNA levels. This acidosis-induced increase in glutamine transport activity was due to a stimulation of transporter maximal transport capacity (V(max) 13.6+/-0.73 nmole/mg protein/minute in acidosis vs. 6.3+/-0.46 nmole/mg protein/minute in control) rather than a change in transporter affinity (K(m)=0.23+/-0.02 mmol/L glutamine in acidosis vs. 0.19+/-0.02 mmol/L glutamine in control). This acidosis-stimulated glutamine transport activity was blocked by actinomycin-D or cycloheximide. Cellular mitogen-activated protein kinase (MAPK) MEK1/2 and p42/44 levels were elevated in acidotic cells, and the acidosis-induced glutamine transport activity was blocked by the MAPK MEK 1 inhibitor PD 98059. Acidosis stimulates glutamine transport in Caco-2 cells via signaling pathways that lead to transcription of the glutamine transporter gene and translation of functional transporters. Mitogen-activated protein kinases are key intracellular regulators involved in this signal transduction cascade. An increased availability of glutamine to cells subjected to redox stress may help in maintaining cellular integrity.

Academic medicine and the search for meaning and purpose.

The transformation of the health care industry into a marketplace governed by commercialism and free competition challenges the doctrine of medicine as a profession valuing service to the patient above financial reward. Many physicians have become disenchanted with their ability to serve as advocates for and provide care to their patients. Financial success, the measure of the marketplace, has become the dominant standard of measurement or "value" for most academic medical centers (AMCs). Many doctors report their work is less fulfilling. As a result, all three social missions-patient care, teaching, and research-are in jeopardy. The growth of modernism, preeminence of biomedical research, and dominance of a market-driven clinical enterprise will continue to pose challenges to the health care system in the United States. However, AMCs can provide the leadership and serve as the ambassadors through which the health care system can be renewed with a sense of direction and purpose. Renewal must begin with more open discourse about what we value in health care and what kind of medical profession we want to have, to include addressing questions such as: What does it mean to be an academic physician? What gives my work meaning and purpose? This kind of dialogue could easily be built into the medical students' curricula and residency training programs, with the faculty taking the lead.

The future-oriented department chair.

The authors describe the current dilemma facing academic health centers (AHCs) as they recruit department chairs. In the past, leaders at AHCs predominantly were concerned with fulfilling the esteemed tripartite missions of patient care, research, and education. Today, their time and energy are occupied by a different set of tasks that have a distinct business orientation, including winning contracts, enhancing revenue, reducing costs, recruiting and managing a diverse workforce, and dealing with consumer satisfaction and marketing. New visions and strategies must be developed--requiring different dimensions of leadership. The authors offer concrete recommendations for recruiting, retaining, and sustaining department chairs, and argue that a deliberative, thoughtful process of engaging chair candidates should begin by focusing on the candidates' values as a first priority. Candidates who most clearly share organizational values should then be engaged in an iterative process of developing a shared vision, resulting in a letter of agreement that explicitly states the mutual expectations and commitments of both the organization and the candidate. Once department chairs are in place, ongoing development through leadership training, mentoring, and other investments help to retain and sustain them.

Sources of error in delayed payment of physician claims.

BACKGROUND AND OBJECTIVES: Our objectives were to determine the distribution of errors and estimate the magnitude of the burden of delayed payments in a large physician group practice. METHODS: A 25% random sample (n=775) was taken from all billed records of a physician group practice in the Pacific Northwest that were delayed 6 months or more as of June 30, 2001. The source and specific reasons for payment delays, as well as the amount of each unpaid invoice, were determined by electronic documentation or telephone calls to the payor. Analysis of variance was used to determine whether the amount of the invoice was associated with the source and reason of error. RESULTS: The source of delayed payments due to provider, payor, patient, and technical error were 36.1%, 28.1%, 14.5%, and 21.3%, respectively. The most-frequent reasons for delayed payment were that the provider incorrectly set up the account (15.2%), the provider did not follow up on denial (12.9%), and the payor incorrectly processed the invoice (11.6%). Analysis of variance suggested that the invoice amount was not significantly associated with the source but was significantly different across reasons for delayed payment. The potential financial impact of earlier recovery of payment was $262,270. CONCLUSIONS: In these data, provider and payor errors accounted for almost two thirds of delayed payments. The most promising avenue for providers to reduce delayed payments is by reducing their own errors. Eliminating the two most common errors would result in a more timely recovery of nearly $70,000 in revenues.