OprF functions as a latch to direct Outer Membrane Vesicle release in Pseudomonas aeruginosa.

Bacterial Outer Membrane Vesicles (OMVs) contribute to virulence, competition, immune avoidance and communication. This has led to great interest in how they are formed. To date, investigation has focused almost exclusively on what controls the initiation of OMV biogenesis. Regardless of the mechanism of initiation, all species face a similar challenge before an OMV can be released: How does the OM detach from the underlying peptidoglycan (PG) in regions that will ultimately bulge and then vesiculate? The OmpA family of OM proteins (OprF in P. aeruginosa) is widely conserved and unusually abundant in OMVs across species considering their major role in PG attachment. OmpA homologs also have the interesting ability to adopt both PG-bound (two-domain) and PG-released (one-domain) conformations. Using targeted deletion of the PG-binding domain we showed that loss of cell wall association, and not general membrane destabilization, is responsible for hypervesiculation in OprF-modified strains. We therefore propose that OprF functions as a 'latch', capable of releasing PG in regions destined to become OMVs. To test this hypothesis, we developed a protocol to assess OprF conformation in live cells and purified OMVs. While >90% of OprF proteins exist in the two-domain conformation in the OM of cells, we show that the majority of OprF in OMVs is present in the one-domain conformation. With this work, we take some of the first steps in characterizing late-stage OMV biogenesis and identify a family of proteins whose critical role can be explained by their unique ability to fold into two distinct conformations.

Does the Use of an Intra-Articular Local Anesthetic Injection During Total Hip Arthroplasty Reduce Patient Reported Pain Scores or Patient Opioid Consumption?

BACKGROUND: During primary total hip arthroplasty (THA), some surgeons use an intra-articular injection (IAI) containing 200 mg ropivacaine to target postoperative pain. There is no clear consensus on the efficacy of an IAI alone. The purpose of this study is to evaluate the effect of a 200 mg ropivacaine IAI on pain scores, opioid consumption, and mobility for primary THA patients. METHODS: We retrospectively reviewed 571 patients who underwent primary THA at a single institution. Patients were grouped according to those who received a 200 mg ropivacaine IAI and those who did not. Primary outcome measures for this study included pain scores, morphine milligram equivalents (MMEs) dosed, distance of ambulation achieved, and time to ambulation. RESULTS: The intervention group reported higher average pain scores with activity than the control group (P = .024). The intervention group also required higher MMEs. When striated by hour, a statistically significant uptick in pain started at 16 hours (P = .0009) and persisted to 28 hours (P = .032) in patients receiving a 200 mg ropivacaine IAI. This correlated with an increase in MMEs seen at hour 24 through 32 (P = .003 to P = .012). Level of ambulation, time to ambulation, and distance ambulated did not differ between groups. An IAI of 200 mg ropivacaine also appeared to lead to higher pain scores and higher opioid doses in males. CONCLUSION: The IAI does not appear to reduce postoperative pain scores or MMEs dosed for THA patients. More research is needed to look at the utilization and efficacy of intra-articular ropivacaine, especially focusing on functional outcomes and gender differences.

Impact of Student-Run Clinics on Students' Attitudes Toward People Experiencing Homelessness.

INTRODUCTION: Student-run clinics can supplement medical education by exposing students to diverse clinical scenarios and collaborating with underresourced populations. We examined the impact of volunteering at THRIVE, a student-run bridge clinic located within sheltered housing for individuals with substance use disorder, on students' attitudes toward people experiencing homelessness (PEH). METHODS: This cohort study analyzed pre- and postsurvey matched responses from nonvolunteer and volunteer first-year medical students utilizing the Health Professional Attitudes Towards the Homeless (HPATHI) tool, totaled into three subcategories: Cynicism, Social Advocacy, and Personal Advocacy. We evaluated the association between change in scores and volunteering utilizing Student t tests and adjusting for participant characteristics using multivariable regression analysis. RESULTS: We received 106 responses (53% response rate); 58 students (55%) volunteered at the clinic and were mostly female (62%), White (52%), and had previous experience working with PEH (71%). The mean change in Personal Advocacy scores was higher for volunteers compared to nonvolunteers, even when adjusting for respondent characteristics (P=.02). Additionally, students who held a prior advanced degree and/or current enrollment in the master of bioethics program (Higher Education Students) had a positive association with change in Personal Advocacy scores (P=.02). CONCLUSION: Volunteering at the THRIVE Clinic appears to impact the Personal Advocacy scores of medical students. This suggests that interacting with PEH early in students' career may be associated with a commitment to working with this population. However, our study has multiple limitations, including self-selection bias, limited sample size, and unclear permanence of students' attitudes over time. Further studies of this cohort could help clarify the significance and permanence of volunteering in student-run clinics.

Too little too late? Communication with patients with congenital heart disease about challenges of adult life.

OBJECTIVE: To investigate the experiences and communication preferences of adult patients with congenital heart disease (CHD) in the domains of employment, insurance, and family planning. DESIGN: Patients ≥ 18 years of age completed a questionnaire about experiences and communication preferences regarding employment, health insurance, and family planning. RESULTS: Of 152 patients (median age = 33 years, 50% female, 35% with CHD of great complexity), one in four reported work-related problems due to CHD and a quarter also recalled a previous gap in health insurance. Of females, 29% experienced an unplanned pregnancy. The median importance of discussion ratings (on a 0-10 scale) were 3.5 (employment), 6.0 (insurance), and 8.0 (family planning). Few patients recalled discussions about employment (19%) or health insurance (20%). Over half recalled discussions about family planning, although males were less likely to have had these discussions than females (24% vs 86%, P < .001). Across the three domains, patients identified 16-18 years as the most appropriate age to initiate discussion, although for patients who recalled discussions, they typically occurred between 20 and 25 years. CONCLUSIONS: Adults with CHD commonly face employment, health insurance, and family planning challenges. However, discussions about these matters occur with less frequency than recommended and at older ages than patients would prefer. Communication about such issues should be incorporated into a comprehensive educational curriculum for adolescents during the process of transition to adult care.

Accuracy of risk prediction scores in pregnant women with congenital heart disease.

OBJECTIVE: To assess performance of risk stratification schemes in predicting adverse cardiac outcomes in pregnant women with congenital heart disease (CHD) and to compare these schemes to clinical factors alone. DESIGN: Single-center retrospective study. SETTING: Tertiary care academic hospital. PATIENTS: Women ≥18 years with International Classification of Diseases, Ninth Revision, Clinical Modification codes indicating CHD who delivered between 1998 and 2014. CARPREG I and ZAHARA risk scores and modified World Health Organization (WHO) criteria were applied to each woman. OUTCOME MEASURES: The primary outcome was defined by ≥1 of the following: arrhythmia, heart failure/pulmonary edema, transient ischemic attack, stroke, dissection, myocardial infarction, cardiac arrest, death during gestation and up to 6 months postpartum. RESULTS: Of 178 women, the most common CHD lesions were congenital aortic stenosis (15.2%), ventricular septal defect (13.5%), atrial septal defect (12.9%), and tetralogy of Fallot (12.9%). Thirty-five women (19.7%) sustained 39 cardiac events. Observed vs expected event rates were 9.9% vs 5% (P = .02) for CARPREG I score 0 and 26.1% vs 7.5% (P < .001) for ZAHARA scores 0.51-1.5. ZAHARA outperformed CARPREG I at predicting adverse cardiovascular outcomes (AUC 0.80 vs 0.72, P = .03) but was not significantly better than modified WHO. Clinical predictors of adverse cardiac event were symptoms (P = .002), systemic ventricular dysfunction (P < .001), and subpulmonary ventricular dysfunction (P = .03) with an AUC 0.83 comparable to ZAHARA (P = .66). CONCLUSIONS: CARPREG I and ZAHARA scores underestimate cardiac risk for lower risk pregnancies in these women. Of the three risk schemes, CARPREG I performed least well in predictive capacity. Clinical factors specific to the population studied are comparable to stratification schemes.

Early Recurrence of First Unprovoked Seizures in Children.

OBJECTIVES: The risk of early seizure recurrences after first unprovoked seizures in children is largely unknown. We aimed to determine the rate of seizure recurrence within 14 days of first unprovoked seizures in children and identify associated risk factors. Secondarily, we aimed to determine the risk of recurrence at 48 hours and 4 months. METHODS: We conducted a secondary analysis of a multicenter cohort study of children 29 days to 18 years with first unprovoked seizures. Emergency department (ED) clinicians completed standardized histories and physical examinations. The primary outcome, recurrent seizure at 14 days, and the secondary outcomes, recurrence at 48 hours and 4 months, were assessed by telephone follow-up and medical record review. For each recurrence time point, we excluded those patients for whom no seizure had recurred but chronic antiepileptic drugs had been initiated. RESULTS: A total of 475 patients were enrolled in the parent study. Of evaluable patients for this secondary analysis, 26 of 392 (6.6%, 95% confidence interval [CI] = 4.4%-9.6%) had recurrences within 48 hours of the incident seizures, 58 of 366 (15.8%, 95% CI = 12.3%-20.0%) had recurrences within 14 days, and 107 of 340 (31.5%, 95% CI = 26.6%-36.7%) had recurrences within 4 months. On logistic regression analysis, age younger than 3 years was independently associated with a higher risk of 14-day recurrence (adjusted odds ratio [OR] = 2.1, 95% CI = 1.2-3.7; p = 0.01). Having had more than one seizure within the 24 hours prior to ED presentation was independently associated with a higher risk of seizure recurrence at 48 hours (adjusted OR = 4.3, 95% CI = 1.9-9.8; p < 0.001). CONCLUSIONS: Risk of seizure recurrence 14 days after first unprovoked seizures in children is substantial, with younger children at higher risk. Prompt completion of an electroencephalogram and evaluation by a neurologist is appropriate for these children.

Advance Care Planning in Adults with Congenital Heart Disease: A Patient Priority.

BACKGROUND: Adult congenital heart disease (ACHD) patients with moderate or great defect complexity are at risk for premature death. Although early engagement in advance care planning (ACP) is recommended, previous research suggests that it seldom occurs. METHODS: This study investigated ACHD patient preferences for ACP and factors that impact preferences. ACHD patients completed an ACP preferences questionnaire, the Hospital Anxiety and Depression Scale and a measure of attachment styles. RESULTS: Of 152 ACHD patients (median age 33years, 50% female), 13% reported previous ACP discussions with providers and 21% had completed advance directives. On a 0-10 scale, the median rating for the importance of discussing ACP with providers was 7; 18years was identified as the most appropriate age to initiate this dialogue. Higher ratings for the importance of discussing ACP with providers was observed in patients who were female (p=0.03), had lower disease complexity (p=0.03), and had elevated anxiety symptoms (p=0.001); elevated anxiety remained significant in a multivariable model. Interest in receiving information about life expectancy (61% overall) was greater among patients with lower disease complexity (p=0.04) and a history of ≥2 cardiac surgeries (p=0.01); disease complexity remained significant in a multivariable model. CONCLUSIONS: As a group, ACHD patients value the opportunity for ACP discussions and prefer earlier communication. Although some clinicians might avoid ACP discussions in patients who are generally more anxious or have less complex CHD, such avoidance does not appear to be warranted.

A Comparison of Perioperative Management of Anomalous Aortic Origin of a Coronary Artery Between an Adult and Pediatric Cardiac Center.

BACKGROUND: Anomalous aortic origin of a coronary artery (AAOCA) presents in varying age-groups. Assuming management algorithms differ between pediatric and adult institutions, we compared the perioperative management of patients with AAOCA at two such centers. METHODS: A retrospective review was conducted at a pediatric and an adult institution of patients 14 years or older who underwent surgical repair of AAOCA between January 2000 and May 2014. RESULTS: Twenty patients from the pediatric center (median age: 16.5 years, range: 14-18 years) and nine patients from the adult center (median age: 40 years, range: 37-52 years) were included. An anomalous aortic origin of a right coronary artery was the most frequent pathology at each institution. Chest pain was the most common presenting symptom at both institutions. Preoperative echocardiography was performed in 95% patients at the pediatric center and in 100% of patients at the adult center. Cardiac catheterization was utilized more frequently at the adult center, and cardiac magnetic resonance imaging more commonly employed at the pediatric center. Isolated coronary unroofing was performed in 19 of 20 cases at the pediatric center and in only 2 (22%) cases at the adult institution, both by congenitally trained cardiac surgeons. More concomitant cardiac procedures were performed at the adult center with associated longer operative times and hospital stays. CONCLUSION: Management strategies for AAOCA vary depending on both patient-specific factors and expertise of the managing team. Further studies are needed to optimally standardize diagnostic and treatment pathways regardless of location venue.

Delayed Diagnosis of Vesicouterine Fistula After Treatment for Mixed Urinary Incontinence: Menstrual Cup Management and Diagnosis.

INTRODUCTION: A vesicouterine fistula is a rare form of urogenital fistula, yet there is increasing prevalence in the United States because of the rising rate of cesarean deliveries. Vesicouterine fistulas have various presentations including menouria, hematuria, or urinary incontinence. CASE PRESENTATION: A 39-year-old multiparous woman presented with urine leakage after her third cesarean delivery. She had been treated for mixed urinary incontinence with overactive bladder medications and a midurethral sling with continued complaints of urine leakage. The patient noticed her symptoms of urine leakage improved during menses when she used a menstrual cup. After confirmation of vesicouterine fistula, the patient underwent robotic-assisted surgery and her symptoms of insensible urine leakage resolved. CONCLUSIONS: When evaluating women with urinary incontinence and a history of cesarean deliveries, use of menstrual cup may aid in the diagnosis of vesicouterine fistula. Robotic-assisted laparoscopic repair with tissue interposition flap is an efficacious minimally invasive method for treatment of vesicouterine fistula.

Postmastectomy radiation therapy and immediate autologous breast reconstruction: integrating perspectives from surgical oncology, radiation oncology, and plastic and reconstructive surgery.

BACKGROUND AND OBJECTIVES: The effect of postmastectomy radiation therapy (PMRT) on immediately reconstructed abdominal wall-based tissue remains imprecisely defined. We evaluated evidence from all fields involved in care of the breast cancer patient in order to advance a unified recommendation regarding this therapeutic sequence. METHODS: We performed a MEDLINE and manual reference search to identify studies of PMRT with immediate autologous breast reconstruction. Inclusion criteria required studies to describe patients, flaps, and complication rates. Analyses were based on a random effects model. Surgical and radiation oncology literature was reviewed. RESULTS: Eleven retrospective studies of 337 patients with an average follow-up of 18-60 months (out of 268 patients) were selected for inclusion. Overall rates of fat necrosis, revisional surgery, volume loss, and fibrosis/contracture ranged from 16.9% to 35.4%. One out of 260 patients experienced total flap loss. There was an increased probability of fat necrosis in the irradiated breast (OR = 3.13, 95% CI = 1.42-6.89, P = 0.005) among three studies with non-irradiated controls. Five studies evaluated aesthetics with variable outcomes. CONCLUSIONS: There is mixed evidence for the utility of PMRT with immediate autologous abdominal wall breast reconstruction. Further investigation requires prospective studies with collaboration among surgical oncologists, radiation oncologists, and plastic surgeons.

Hedgehog signaling inhibition blocks growth of resistant tumors through effects on tumor microenvironment.

Hedgehog (Hh) signaling is implicated in bone development and cellular transformation. Here we show that inhibition of Hh pathway activity inhibits tumor growth through effects on the microenvironment. Pharmacologic inhibition of the Hh effector Smoothened (Smo) increased trabecular bone in vivo and inhibited osteoclastogenesis in vitro. In addition, enhanced Hh signaling due to heterozygosity of the Hh inhibitory receptor Patched (Ptch1(+/-)) increased bone resorption, suggesting direct regulation of osteoclast (OC) activity by the Hh pathway. Ptch1(+/-) mice had increased bone metastatic and subcutaneous tumor growth, suggesting that increased Hh activation in host cells promoted tumor growth. Subcutaneous growth of Hh-resistant tumor cells was inhibited by LDE225, a novel orally bioavailable SMO antagonist, consistent with effects on tumor microenvironment. Knockdown of the Hh ligand Sonic Hh (SHH) in these cells decreased subcutaneous tumor growth and decreased stromal cell production of interleukin-6, indicating that tumor-derived Hh ligands stimulated tumor growth in a paracrine fashion. Together our findings show that inhibition of the Hh pathway can reduce tumor burden, regardless of tumor Hh responsiveness, through effects on tumor cells, OCs, and stromal cells within the tumor microenvironment. Hh may be a promising therapeutic target for solid cancers and bone metastases.

Persistent expression of activated Notch inhibits corticotrope and melanotrope differentiation and results in dysfunction of the HPA axis.

The hypothalamic-pituitary-adrenal (HPA) axis is an important regulator of energy balance, immune function and the body's response to stress. Signaling networks governing the initial specification of corticotropes, a major component of this axis, are not fully understood. Loss of function studies indicate that Notch signaling may be necessary to repress premature differentiation of corticotropes and to promote proliferation of pituitary progenitors. To elucidate whether Notch signaling must be suppressed in order for corticotrope differentiation to proceed and whether Notch signaling is sufficient to promote corticotrope proliferation, we examined the effects of persistent Notch expression in Pomc lineage cells. We show that constitutive activation of the Notch cascade inhibits the differentiation of both corticotropes and melanotropes and results in the suppression of transcription factors required for Pomc expression. Furthermore, persistent Notch signaling traps cells in the intermediate lobe of the pituitary in a progenitor state, but has no effect on pituitary proliferation. Undifferentiated cells are eliminated in the first two postnatal weeks in these mice, resulting in a modest increase in CRH expression in the paraventricular nucleus, hypoplastic adrenal glands and decreased stress-induced corticosterone levels. Taken together, these findings show that Notch signaling is sufficient to prevent corticotrope and melanotrope differentiation, resulting in dysregulation of the HPA axis.

Numb deletion in POMC-expressing cells impairs pituitary intermediate lobe cell adhesion, progenitor cell localization, and neuro-intermediate lobe boundary formation.

The pituitary gland contains six distinct hormone-secreting cell types that are essential for basic physiological processes including fertility and responding to stress. Formation of hormone-secreting cells during development relies on Notch signaling to prevent progenitors from prematurely differentiating. The nature of the signal curtailing Notch signaling in the pituitary is unknown, but a good candidate is the endocytic adaptor protein NUMB. NUMB targets Notch for proteolytic degradation, but it also has a broad range of actions, including stabilizing adherens junctions through interactions with cadherins and influencing cell proliferation by stabilizing expression of the tumor suppressor protein p53. Here, we show that NUMB and its closely related homolog, NUMBLIKE, are expressed in undifferentiated cells during development and later in gonadotropes in the anterior lobe and melanotropes of the intermediate lobe. All four isoforms of NUMB, are detectable in the pituitary, with the shorter forms becoming more prominent after adolescence. Conditionally deleting Numb and Numblike in the intermediate lobe melanotropes with Pomc Cre mice dramatically alters the morphology of cells in the intermediate lobe, coincident with impaired localization of adherens junctions proteins including E-CADHERIN, N-CADHERIN, ß-CATENIN, and α-CATENIN. Strikingly, the border between posterior and intermediate lobes is also disrupted. These mice also have disorganized progenitor cells, marked by SOX2, but proliferation is unaffected. Unexpectedly, Notch activity appears normal in conditional knockout mice. Thus, Numb is critical for maintaining cell-cell interactions in the pituitary intermediate lobe that are essential for proper cell placement.

Cellular mechanism of decreased bone in Brtl mouse model of OI: imbalance of decreased osteoblast function and increased osteoclasts and their precursors.

The Brtl mouse, a knock-in model for moderately severe osteogenesis imperfecta (OI), has a G349C substitution in half of type I collagen alpha1(I) chains. We studied the cellular contribution to Brtl bone properties. Brtl cortical and trabecular bone are reduced before and after puberty, with BV/TV decreased 40-45%. Brtl ObS/BS is comparable to wildtype, and Brtl and wildtype marrow generate equivalent number of colony-forming units (CFUs) at both ages. However, OcS/BS is increased in Brtl at both ages (36-45%), as are TRACP(+) cell numbers (57-47%). After puberty, Brtl ObS/BS decreases comparably to wildtype mice, but osteoblast matrix production (MAR) decreases to one half of wildtype values. In contrast, Brtl OcS falls only moderately (approximately 16%), and Brtl TRACP staining remains significantly elevated compared with wildtype. Consequently, Brtl BFR decreases from normal at 2 mo to one half of wildtype values at 6 mo. Immunohistochemistry and real-time RT-PCR show increased RANK, RANKL, and osteoprotegerin (OPG) levels in Brtl, although a normal RANKL/OPG ratio is maintained. TRACP(+) precursors are markedly elevated in Brtl marrow cultures and form more osteoclasts, suggesting that osteoclast increases arise from more RANK-expressing precursors. We conclude that osteoblasts and osteoclasts are unsynchronized in Brtl bone. This cellular imbalance results in declining BFR as Brtl ages, consistent with reduced femoral geometry. The disparity in cellular number and function results from poorly functioning osteoblasts in addition to increased RANK-expressing precursors that respond to normal RANKL/OPG ratios to generate more bone-resorbing osteoclasts. Interruption of the stimulus that increases osteoclast precursors may lead to novel OI therapies.