A single-cell atlas of human and mouse white adipose tissue.

White adipose tissue, once regarded as morphologically and functionally bland, is now recognized to be dynamic, plastic and heterogenous, and is involved in a wide array of biological processes including energy homeostasis, glucose and lipid handling, blood pressure control and host defence1. High-fat feeding and other metabolic stressors cause marked changes in adipose morphology, physiology and cellular composition1, and alterations in adiposity are associated with insulin resistance, dyslipidemia and type 2 diabetes2. Here we provide detailed cellular atlases of human and mouse subcutaneous and visceral white fat at single-cell resolution across a range of body weight. We identify subpopulations of adipocytes, adipose stem and progenitor cells, vascular and immune cells and demonstrate commonalities and differences across species and dietary conditions. We link specific cell types to increased risk of metabolic disease and provide an initial blueprint for a comprehensive set of interactions between individual cell types in the adipose niche in leanness and obesity. These data comprise an extensive resource for the exploration of genes, traits and cell types in the function of white adipose tissue across species, depots and nutritional conditions.

Comparative outcomes of open mesenteric bypass after a failed endovascular or open mesenteric revascularization for chronic mesenteric ischemia.

INTRODUCTION: Clinical practice guidelines have recommended an endovascular-first approach (ENDO) for the management of patients with chronic mesenteric ischemia (CMI), whereas an open mesenteric bypass (OMB) is proposed for subjects deemed to be poor ENDO candidates. However, the impact of a previous failed endovascular or open mesenteric reconstruction on a subsequent OMB is unknown. Accordingly, this study was designed to examine the results of a remedial OMB (R-OMB) after a failed ENDO or a primary OMB (P-OMB) for patients with recurrent CMI. METHODS: All patients who underwent an OMB from 2002 to 2022 at the University of Florida were reviewed. Outcomes after an R-OMB (ie, history of a failed ENDO or P-OMB) and P-OMB were compared. The primary end point was 30-day mortality, whereas secondary outcomes included complications, reintervention, and survival. The Kaplan-Meier methodology was used to estimate freedom from reintervention and all-cause mortality, whereas multivariable Cox proportional hazards modeling identified predictors of death. RESULTS: A total of 145 OMB procedures (R-OMB, n = 48 [33%]; P-OMB, n = 97 [67%]) were analyzed. A majority of R-OMB operations were performed for a failed stent (prior ENDO, n = 39 [81%]; prior OMB, n = 9 [19%]). R-OMB patients were generally younger (66 ± 9 years vs P-OMB, 69 ± 11 years; P = .09) and had lower incidence of smoking exposure (29% vs P-OMB, 48%; P = .07); however, there were no other differences in demographics or comorbidities. R-OMB was associated with less intraoperative transfusion (0.6 units vs P-OMB, 1.4 units; P = .01), but there were no differences in conduit choice or bypass configuration.The overall 30-day mortality and complication rates were 7% (n = 10/145) and 53% (n = 77/145), respectively, with no difference between the groups. Notably, R-OMB had decreased cardiac (6% vs P-OMB, 21%; P < .01) and bleeding complication rates (2% vs P-OMB, 15%; P = .01). The freedom from reintervention (1 and 5 years: R-OMB: 95% ± 4%, 83% ± 9% vs P-OMB: 97% ± 2%, 93% ± 5%, respectively; log-rank P = .21) and survival (1 and 5 years: R-OMB: 82% ± 6%, 68% ± 9% vs P-OMB: 84% ± 4%, 66% ± 7%; P = .91) were similar. Independent predictors of all-cause mortality included new postoperative hemodialysis requirement (hazard ratio [HR], 7.4, 95% confidence interval [CI], 3.1-17.3; P < .001), pulmonary (HR, 2.7, 95% CI, 1.4-5.3; P = .004) and cardiac (HR, 2.4, 95% CI, 1.1-5.1; P = .04) complications, and female sex (HR, 2.1, 95% CI, 1.03-4.8; P = .04). Notably, R-OMB was not a predictor of death. CONCLUSIONS: The perioperative and longer-term outcomes for a remedial OMB after a failed intraluminal stent or previous open bypass appear to be comparable to a P-OMB. These findings support the recently updated clinical practice guideline recommendations for an endovascular-first approach to treating recurrent CMI due to the significant perioperative complication risk of OMB. However, among the subset of patients deemed ineligible for endoluminal reconstruction after failed mesenteric revascularization, R-OMB results appear to be acceptable and highlight the utility of this strategy in selected patients.

Persistent Acute Kidney Injury is Associated with Poor Outcomes and Increased Hospital Cost in Vascular Surgery.

BACKGROUND: Postoperative acute kidney injury (AKI) is common after major surgery and is associated with increased morbidity, mortality, and cost. Additionally, there are recent studies demonstrating that time to renal recovery may have a substantial impact on clinical outcomes. We hypothesized that patients with delayed renal recovery after major vascular surgery will have increased complications, mortality, and hospital cost. METHODS: A single-center retrospective cohort of patients undergoing nonemergent major vascular surgery between 6/1/2014 and 10/1/2020 was analyzed. Development of postoperative AKI (defined using Kidney Disease Improving Global Outcomes (KDIGO) criteria: >50% or > 0.3 mg/dl absolute increase in serum creatinine relative to reference after surgery and before discharge) was evaluated. Patients were divided into 3 groups: no AKI, rapidly reversed AKI (<48 hours), and persistent AKI (≥48 hours). Multivariable generalized linear models were used to evaluate the association between AKI groups and postoperative complications, 90-day mortality, and hospital cost. RESULTS: A total of 1,881 patients undergoing 1,980 vascular procedures were included. Thirty five percent of patients developed postoperative AKI. Patients with persistent AKI had longer intensive care unit and hospital stays, as well as more mechanical ventilation days. In multivariable logistic regression analysis, persistent AKI was a major predictor of 90-day mortality (odds ratio 4.1, 95% confidence interval 2.4-7.1). Adjusted average cost was higher for patients with any type of AKI. The incremental cost of having any AKI ranged from $3,700 to $9,100, even after adjustment for comorbidities and other postoperative complications. The adjusted average cost for patients stratified by type of AKI was higher among patients with persistent AKI compared to those with no or rapidly reversed AKI. CONCLUSIONS: Persistent AKI after vascular surgery is associated with increased complications, mortality, and cost. Strategies to prevent and aggressively treat AKI, specifically persistent AKI, in the perioperative setting are imperative to optimize care for this population.

Outcomes of Patients with Acute Type B Aortic Dissection and High-Risk Features.

BACKGROUND: Recently the Society for Vascular Surgery (SVS) and Society for Thoracic Surgeons (STS) published contemporary guidelines clearly defining complicated versus uncomplicated acute type B aortic dissections (TBADs) with an additional high-risk grouping. Few studies have evaluated outcomes associated with "high-risk" TBADs. The objective of this study was to assess differences in demographics, clinical presentation, symptom onset, and outcomes in high-risk patients that underwent either thoracic endovascular aortic repair (TEVAR) or best medical management for acute TBAD compared to those with complicated and uncomplicated acute TBAD. METHODS: Patients admitted with acute TBADs from a single academic medical center from October 2011 to March 2020 were analyzed. Per the STS/SVS 2020 guidelines, high risk was defined as refractory pain/hypertension, bloody pleural effusion, aortic diameter >4 cm, false lumen diameter >22 mm, radiographic malperfusion, and early readmission, and complicated was defined as ruptured/malperfusion presentation. Uncomplicated patients were those without malperfusion/rupture and without high-risk features. The primary end-point was inpatient mortality. Secondary end-points included complications, reintervention, and survival. RESULTS: Of the 159 patients identified with acute TBAD, 63 (40%) met the high-risk criteria. In the high-risk cohort, 38 (60%) underwent TEVAR (HR-TEVAR), with refractory pain as the most common indication, while 25 (40%) were managed medically (HR-medical). Malperfusion or rupture was present in 63 (40%) patients (complicated TBAD (C-TBAD)), all of whom underwent TEVAR. An additional 33 patients had no high-risk features and were all managed medically (uncomplicated TBAD). There were no differences in age, body mass index, and race between groups. Among the 4 groups, there were variable distributions in sex, insurance status, and incidence of several baseline comorbidities including congestive heart failure, chronic obstructive pulmonary disease, and renal dysfunction (P < 0.05 for all). C-TBAD had increased length of stay (12, interquartile range [IQR] 9-22) compared to HR-TEVAR (11.5, IQR 7-15), HR-medical (6, IQR 5-8), and uncomplicated TBAD (7, IQR 5-10) (P < 0.01). C-TBAD had decreased days from admission to repair (0, IQR 0-2) compared to HR-TEVAR (3.5, IQR 1-8) (P < 0.01). C-TBAD patients had worse 3-year survival compared to other groups (log-rank P < 0.01), although when in-hospital mortality was excluded, survival was similar among groups (P = 0.37). Of patients initially managed medically, outpatient TEVAR was performed in 6 (24%) HR-medical and 4 (12%) uncomplicated patients, with no difference between rate of intervention between groups (P = 0.22). CONCLUSIONS: High-risk features, as defined in updated SVS/STS guidelines, are common in patients presenting with acute TBAD. High-risk patients had acceptable outcomes when managed either surgically or medically. High-risk patients that underwent TEVAR had improved perioperative outcomes and mortality compared to those undergoing TEVAR for C-TBAD, a finding which may help guide preoperative risk stratification and patient counseling.

National Institutes of Health funding among vascular surgeons is rare.

BACKGROUND: The National Institutes of Health (NIH) is an essential source of funding for vascular surgeons conducting research. NIH funding is frequently used to benchmark institutional and individual research productivity, help determine eligibility for academic promotion, and as a measure of scientific quality. We sought to appraise the current scope of NIH funding to vascular surgeons by appraising the characteristics of NIH-funded investigators and projects. In addition, we also sought to determine whether funded grants addressed recent Society for Vascular Surgery (SVS) research priorities. METHODS: In April 2022, we queried the NIH Research Portfolio Online Reporting Tools Expenditures and Results (RePORTER) database for active projects. We only included projects that had a vascular surgeon as a principal investigator. Grant characteristics were extracted from the NIH Research Portfolio Online Reporting Tools Expenditures and Results database. Principal investigator demographics and academic background information were identified by searching institution profiles. RESULTS: There were 55 active NIH awards given to 41 vascular surgeons. Only 1% (41/4037) of all vascular surgeons in the United States receive NIH funding. Funded vascular surgeons are an average of 16.3 years out of training; 37% (n = 15) are women. The majority of awards (58%; n = 32) were R01 grants. Among the active NIH-funded projects, 75% (n = 41) are basic or translational research projects, and 25% (n = 14) are clinical or health services research projects. Abdominal aortic aneurysm and peripheral arterial disease are the most commonly funded disease areas and together accounted for 54% (n = 30) of projects. Three SVS research priorities are not addressed by any of the current NIH-funded projects. CONCLUSIONS: NIH funding of vascular surgeons is rare and predominantly consists of basic or translational science projects focused on abdominal aortic aneurysm and peripheral arterial disease research. Women are well-represented among funded vascular surgeons. Although the majority of SVS research priorities receive NIH funding, three SVS research priorities are yet to be addressed by NIH-funded projects. Future efforts should focus on increasing the number of vascular surgeons receiving NIH grants and ensuring all SVS research priorities receive NIH funding.

Osteoclastogenesis requires primary cilia disassembly and can be inhibited by promoting primary cilia formation pharmacologically.

The primary cilium is a solitary, sensory organelle with many roles in bone development, maintenance, and function. In the osteogenic cell lineage, including skeletal stem cells, osteoblasts and osteocytes, the primary cilium plays a vital role in the regulation of bone formation and this has made it a promising pharmaceutical target to maintain bone health. While the role of the primary cilium in the osteogenic cell lineage has been increasingly characterized, little is known about the potential impact of targeting the cilium in relation to osteoclasts, a hematopoietic cell responsible for bone resorption. The objective of this study was to determine whether osteoclasts have a primary cilium and to investigate whether or not the primary cilium of macrophages, osteoclast precursors, serves a functional role in osteoclast formation. Using immunocytochemistry, we showed the macrophages have a primary cilium while osteoclasts lack this organelle. Furthermore, we increased macrophage primary cilia incidence and length using fenoldopam mesylate and found that cells undergoing such treatment showed a significant decrease in the expression of osteoclast markers tartrate-resistant acid phosphatase, cathepsin K, and c-Fos as well as decreased osteoclast formation. This work is the first to show that macrophage primary cilia resorption may be a necessary step for osteoclast differentiation. Since primary cilia and pre-osteoclasts are responsive to fluid flow, we applied fluid flow at magnitudes present in the bone marrow to differentiating cells and found that osteoclastic gene expression by macrophages was not affected by fluid-flow mechanical stimulation, suggesting that the role of the primary cilium in osteoclastogenesis is not a mechanosensory one. The primary cilium has been suggested to play a role in bone formation, and our findings indicate that it may also present a means to regulate bone resorption, presenting a dual benefit of developing ciliary-targeted pharmaceuticals for bone disease.

Outcomes of endovascular abdominal aortic aneurysm repair conversion in octogenarians treated at a high-volume aorta center.

BACKGROUND: Endovascular abdominal aortic aneurysm repair (EVAR) has become the dominant treatment strategy for infrarenal abdominal aortic aneurysms but has been especially preferred for octogenarian (age ≥80 years) patients because of concerns surrounding comorbidity severity and physiologic frailty. However, EVAR failure resulting in subsequent open conversion (EVAR-c) has been increasingly reported in older patients, although a paucity of literature focusing on the outcomes in this subgroup is available. The purpose of the present analysis was to evaluate our experience with EVAR-c for octogenarians (age ≥80 years) compared with that for younger patients (age <80 years). METHODS: A retrospective review of all nonmycotic EVAR-c procedures (2002-2020) at a single high-volume academic hospital with a dedicated aorta center (available at: https://www.uf-health-aortic-disease-center) was performed. A total of 162 patients were categorized into octogenarian (age ≥80 years; n = 43) and nonoctogenarian (age <80 years; n = 119) cohorts and compared. The primary end point was 30-day mortality. The secondary end points included complications, 90-day mortality, and overall survival. Cox regression was used to determine the effects of selected covariates on mortality risk. The Kaplan-Meier method was used to estimate survival. RESULTS: No differences in the preadmission EVAR reintervention rates were present (octogenarians, 42%; nonoctogenarians, 43%; P = 1.00) although the interval to the first reintervention was longer for the octogenarians (41 months) than for the nonoctogenarians (15 months; P = .01). In addition, the time to EVAR-c was significantly longer for the octogenarian patients (61 months) than for the nonoctogenarian patients (39 months; P < .01). No difference in rupture presentation was evident (14% vs 10%; P = .6). However, elective EVAR-c occurred less frequently for octogenarians (42%) than for nonoctogenarians (59%; P = .07). The abdominal aortic aneurysm diameter was significantly larger for elective octogenarian EVAR-c (7.8 ± 1.9 cm) than for nonoctogenarian EVAR-c (7.0 ± 1.5 cm; P = .02), and the presence of a type Ia endoleak was the most common indication overall (58%; n = 91). A trend toward greater 30-day mortality was evident for octogenarian patients (16%) compared with nonoctogenarian patients (7%; P = .06). Similarly, the 90-day mortality was greater for the octogenarian patients (26%) than for the nonoctogenarian patients (10%; P = .02). However, the incidence of any complication (56% vs 49%; P = .5), readmission rate (12% vs 6%; P = .3), unplanned reoperation rate (10% vs 5%; P = .5), and length of stay (11 days vs 9 days; P = .3) were not significantly different between the two groups. Age ≥80 years was predictive of short-term mortality after nonelective but not after elective surgery. However, increasing comorbidities, nonelective admission, and renal or mesenteric revascularization showed the strongest association with mortality risk. Survival at 1 and 3 years was not different between the two groups when comparing all patients after the first 90 days postoperatively. CONCLUSIONS: Although the unadjusted perioperative mortality was greater for octogenarian patients, the risk-adjusted elective outcomes were comparable to those for younger EVAR-c patients when treated at a high-volume aortic surgery center. This finding underscores the importance of appropriate patient selection and modulation of operative complexity when feasible to achieve optimal results. Providers caring for octogenarian patients with EVAR failure should consider timely elective referral to high-volume aorta centers to reduce resource usage and the frequency of nonelective presentations.

Endovascular aneurysm repair conversion is an increasingly common indication for open abdominal aortic aneurysm repair.

OBJECTIVE: Although endovascular aneurysm repair (EVAR) reintervention is common, conversion to open repair (EVAR-c) occurs less frequently but can be associated with significant technical complexity and perioperative risk. There is a paucity of data highlighting the evolution of periprocedural results surrounding EVAR-c and change in practice patterns, especially for referral centers that increasingly manage EVAR failures. The purpose of this analysis was to perform a temporal analysis of our EVAR-c experience and describe changes in patient selection, operative details, and outcomes. METHODS: A retrospective single-center review of all open abdominal aortic aneurysm repairs was performed (2002-2019), and EVAR-c procedures were subsequently analyzed. EVAR-c patients (n = 184) were categorized into two different eras (2002-2009, n = 21; 2010-2019, n = 163) for comparison. Logistic regression and Cox proportional hazards modeling were used for risk-adjusted comparisons. RESULTS: A significant increase in EVAR-c as an indication for any type of open aneurysm repair was detected (9% to 27%; P < .001). Among EVAR-c patients, no change in age or individual comorbidities was evident (mean age, 71 ± 9 years); however, the proportion of female patients (P = .01) and American Society of Anesthesiologists classification >3 declined (P = .05). There was no difference in prevalence (50% vs 43%; P = .6) or number (median, 1.5 [interquartile range (IQR), 0-5]) of preadmission EVAR reinterventions; however, time to reintervention decreased (median, 23 [IQR, 6-34] months vs 0 [IQR, 0-22] months; P = .005). In contrast, time to EVAR-c significantly increased (median, 16 [IQR, 9-39] months vs 48 [IQR, 20-83] months; P = .008). No difference in frequency of nonelective presentation (mean, 52%; P = .9] or indication was identified, but a trend toward increasing mycotic EVAR-c was observed (5% vs 15%; P = .09). Use of retroperitoneal exposure (14% vs 77%; P < .0001), suprarenal cross-clamp application (6286%; P = .04), and visceral-ischemia time (median, 0 [IQR, 0-11] minutes vs 5 [IQR, 0-20] minutes; P = .05) all increased. In contrast, estimated blood loss (P trend = .03) and procedure time (P = .008) decreased. The unadjusted elective 30-day mortality rate improved but did not reach statistical significance (elective, 10% vs 5%; P = .5) with no change for non-elective operations (18% vs 16%; P = .9). However, a significantly decreased risk of complications was evident (odds ratio, 0.88; 95% confidence interval, .8-.9; P = .01). One- and 3-year survival was similar over time. CONCLUSIONS: EVAR-c is now a common indication for open abdominal aortic aneurysm repair. Patients frequently present nonelectively and at increasingly later intervals after their index EVAR. Despite increasing technical complexity, decreased complication risk and comparable survival can be anticipated when patients are managed at a high-volume aortic referral center.

Psoas Muscle Area as a Prognostic Factor for Survival in Patients Undergoing Endovascular Aneurysm Repair Conversion.

BACKGROUND: Endovascular aneurysm repair conversion (EVAR-c) is increasingly reported and known to be technically complex and physiologically demanding. It has been proposed that pragmatic anthropomorphic measures such as psoas muscle area (PMA) may reliably quantify levels of preoperative frailty and be used to inform point of care clinical decision-making and patient discussions for a variety of complex operations. To date, there is mixed data supporting use of PMA as a prognostic factor in fenestrated endovascular and open abdominal aortic aneurysms (AAA) repairs; however, no literature exists evaluating the impact of preoperative PMA on EVAR-c results. Therefore, the purpose of this study was to review our EVAR-c experience and evaluate the association of PMA with perioperative and long-term mortality outcomes. METHODS: A retrospective single-center review of all AAA repairs was performed (2002-2019) and EVAR-c procedures were subsequently analyzed (n = 153). Cross-sectional PMA at the mid-body of the L3 vertebrae was measured. The lowest PMA tertile was used as a threshold value to designate patients as having "low" PMA (n = 51) and this cohort was subsequently compared to subjects with "normal" PMA (n = 102). Cox proportional hazards modeling was used to estimate covariate association with all-cause mortality. RESULTS: Patients with low PMA were older (77 vs. 72 years; P = 0.002), more likely to be female (27% vs. 5%; P < 0.001), and had reduced body mass index (26 vs. 29 kg/m2; P = 0.002). Time to conversion, total number of endovascular aneurysm repair (EVAR) reinterventions prior to conversion and elective EVAR-c presentation incidence were similar; however, patients with low PMA had larger aneurysms (8.3 vs. 7.5 cm; P = 0.01) and increased post-EVAR sac growth (2.3 vs. 1 cm; P = 0.005). Unadjusted inpatient mortality was significantly greater for low PMA patients (16% vs. normal PMA, 5%, P = 0.02). Similarly, the total number of complications was higher among low PMA subjects (1.5 ± 1.9 vs. normal PMA, 0.9 ± 1.5; P = 0.02). Although frequency of major adverse cardiovascular events and new onset inpatient hemodialysis were similar, low PMA patients had a more than four-fold increased likelihood of having persistent requirement of hemodialysis at discharge (18% vs. 4%,P = 0.01). The low PMA group had decreased survival at 1 and 5 years, respectively (77 ± 5%, 65 ± 6% vs. normal PMA, 86 ± 3%, 82% ± 5%; log-rank P = 0.03). Low PMA was an independent predictor of mortality with every 100 mm2 increase in PMA being associated with a 15% reduction in mortality (hazard ratio: 0.85,95% confidence interval:, 0.74-0.97; P = 0.02). CONCLUSIONS: Among EVAR-c patients, subjects with low preoperative PMA had higher rates of postoperative complications and worse overall survival. PMA assessments may be a useful adjunct to supplement traditional risk-stratification strategies when patients are being considered for EVAR-c.

Surgical Treatment of True Superior Mesenteric Artery Aneurysms.

BACKGROUND: Superior mesenteric artery aneurysms (SMAAs) are a rare clinical problem that can be associated with significant morbidity and mortality. The optimal surgical approach for both mycotic and degenerative SMAAs remains poorly defined. The study was designed to review our institutional experience and develop a treatment algorithm. METHODS: A single-institution, retrospective review was performed to document presentation, treatment, and outcomes of patients undergoing surgical repair of SMAAs from 2003 to 2020. The primary end-point was 30-day mortality, and secondary end-points included complications, patency, freedom from reinfection, freedom from reintervention, and survival. RESULTS: Eighteen patients (mean age: 46 ± 16 yrs; 50% male; mean diameter 2.4 ± 2.0 cm) underwent treatment of mycotic (50%) or degenerative (50%) SMAAs. Abdominal pain (66%) was the most common presenting symptom, and the diagnosis was confirmed with CT arteriography. Endocarditis secondary to intravenous drug abuse was responsible for most (88%) of the mycotic SMAAs, with a majority (66%) having positive cultures and Streptococcus being the most common organism. The majority (61%) of patients underwent urgent or emergent repair with aneurysmectomy and interposition saphenous vein bypass being the most common treatment of mycotic SMAAs while aneurysmectomy and prosthetic bypass were used most frequently for degenerative aneurysms. The operative mortality rate was 6% with a major complication rate of 17% (n = 3 patients: respiratory failure/reintubation-1, pulmonary embolism-1, necrotizing pancreatitis/graft disruption and death-1). The single death occurred in a patient with a degenerative aneurysm that developed postoperative pancreatitis and multiple organ dysfunction. The mean clinical follow-up time was 25 ± 48 (95% CI 1-48) months. The estimated primary patency, freedom from reinfection, and freedom from reintervention were 93 ± 7 %, 94 ± 5%, and 94 ± 5%, respectively, at 1 year. The overall mean survival was 55 ± 51 (95% CI 30-80) months with an estimated survival at 3 years of 77 ± 10%. CONCLUSIONS: SMAAs associated with both degenerative and mycotic etiologies can be treated using a variety of surgical approaches with acceptable morbidity and mortality. Mycotic SMAAs should likely be repaired, regardless of size, while the indications for asymptomatic, degenerative aneurysms remain to be defined by further natural history studies.

Primary cilia are necessary for Prx1-expressing cells to contribute to postnatal skeletogenesis.

Although Prx1 (also known as PRRX1)-expressing cells and their primary cilia are critical for embryonic development, they have yet to be studied in the context of postnatal skeletogenesis owing to the lethality of mouse models. A tamoxifen-inducible Prx1 model has been developed, and we determined that expression directed by this promoter is highly restricted to the cambium layers in the periosteum and perichondrium after birth. To determine the postnatal role of these cambium layer osteochondroprogenitors (CLOPs) and their primary cilia, we developed models to track the fate of CLOPs (Prx1CreER-GFP;Rosa26tdTomato) and selectively disrupt their cilia (Prx1CreER-GFP;Ift88fl/fl). Our tracking studies revealed that CLOPs populate cortical and trabecular bone, the growth plate and secondary ossification centers during the normal program of postnatal skeletogenesis. Furthermore, animals lacking CLOP cilia exhibit stunted limb growth due to disruptions in endochondral and intramembranous ossification. Histological examination indicates that growth is stunted due to limited differentiation, proliferation and/or abnormal hypertrophic differentiation in the growth plate. Collectively, our results suggest that CLOPs are programmed to rapidly populate distant tissues and produce bone via a primary cilium-mediated mechanism in the postnatal skeleton.

"Peek port": avoiding conversion during laparoscopic colectomy-an update.

PURPOSE: To assess the efficacy of a method to avoid conversion to laparotomy in patients considered for laparoscopic colectomy. Patients considered being at high risk for conversion to formal laparotomy were initially approached via a small midline incision ("peek port") with the laparoscopic equipment readily available but unopened. If intraperitoneal conditions were favorable, the procedure was performed using hand-assisted laparoscopy (HALS); if intraperitoneal conditions were unfavorable, the incision was extended to a formal laparotomy. METHODS: Data from 664 patients from a single surgeon brought to the operating room with the intention of proceeding with laparoscopic colectomy (either via straight laparoscopy or HALS) were retrieved from a prospective database. Comparison of conversion rates between groups was performed using χ2 analysis. RESULTS: The study population consisted of 361 men and 303 women with a mean age of 61 years. Inflammatory conditions accounted for 40% of the diagnoses and enteric fistulas were present in 12%. Of the 79 patients who underwent initial "peek port" exploration, 38 (48%) underwent immediate extension to formal laparotomy, whereas 41 (52%) underwent HALS colectomy, with one subsequent conversion from HALS to formal laparotomy. Of the 585 patients initially approached laparoscopically, 14 (2%) required conversion to laparotomy. Of the 626 patients from both groups who underwent laparoscopy, the overall conversion to laparotomy rate was 15/626 (2%). DISCUSSION: The "peek port" approach to the patients with a potentially hostile abdomen allows for prompt assessment of intraperitoneal conditions and is associated with an overall low rate of conversion from laparoscopy to laparotomy during colectomy. This technique may reduce expense and morbidity for patients who ultimately require laparotomy, while allowing some patients with complex disease to be managed laparoscopically who would not normally be considered for a minimally invasive procedure.

NCoR1-independent mechanism plays a role in the action of the unliganded thyroid hormone receptor.

Nuclear receptor corepressor 1 (NCoR1) is considered to be the major corepressor that mediates ligand-independent actions of the thyroid hormone receptor (TR) during development and in hypothyroidism. We tested this by expressing a hypomorphic NCoR1 allele (NCoR1ΔID), which cannot interact with the TR, in Pax8-KO mice, which make no thyroid hormone. Surprisingly, abrogation of NCoR1 function did not reverse the ligand-independent action of the TR on many gene targets and did not fully rescue the high mortality rate due to congenital hypothyroidism in these mice. To further examine NCoR1's role in repression by the unliganded TR, we deleted NCoR1 in the livers of euthyroid and hypothyroid mice and examined the effects on gene expression and enhancer activity measured by histone 3 lysine 27 (H3K27) acetylation. Even in the absence of NCoR1 function, we observed strong repression of more than 43% of positive T3 (3,3',5-triiodothyronine) targets in hypothyroid mice. Regulation of approximately half of those genes correlated with decreased H3K27 acetylation, and nearly 80% of these regions with affected H3K27 acetylation contained a bona fide TRß1-binding site. Moreover, using liver-specific TRß1-KO mice, we demonstrate that hypothyroidism-associated changes in gene expression and histone acetylation require TRß1. Thus, many of the genomic changes mediated by the TR in hypothyroidism are independent of NCoR1, suggesting a role for additional signaling modulators in hypothyroidism.

Primary cilia: Cell and molecular mechanosensors directing whole tissue function.

Primary cilia are immotile, microtubule-based organelles extending from the surface of nearly every mammalian cell. Mechanical stimulation causes deflection of the primary cilium, initiating downstream signaling cascades to the rest of the cell. The cilium forms a unique subcellular microdomain, and defects in ciliary protein composition or physical structure have been associated with a myriad of human pathologies. In this review, we discuss the importance of ciliary mechanotransduction at the cell and tissue level, and how furthering our molecular understanding of primary cilia mechanobiology may lead to therapeutic strategies to treat human diseases.

Improved ZnS nanoparticle properties through sequential NanoFermentation.

Sequential NanoFermentation (SNF) is a novel process which entails sparging microbially produced gas containing H2S from a primary reactor through a concentrated metal-acetate solution contained in a secondary reactor, thereby precipitating metallic sulfide nanoparticles (e.g., ZnS, CuS, or SnS). SNF holds an advantage over single reactor nanoparticle synthesis strategies, because it avoids exposing the microorganisms to high concentrations of toxic metal and sulfide ions. Also, by segregating the nanoparticle products from biological materials, SNF avoids coating nanoparticles with bioproducts that alter their desired properties. Herein, we report the properties of ZnS nanoparticles formed from SNF as compared with ones produced directly in a primary reactor (i.e., conventional NanoFermentation, or "CNF"), commercially available ZnS, and ZnS chemically synthesized by bubbling H2S gas through a Zn-acetate solution. The ZnS nanoparticles produced by SNF provided improved optical properties due to their smaller crystallite size, smaller overall particle sizes, reduced biotic surface coatings, and reduced structural defects. SNF still maintained the advantages of NanoFermentation technology over chemical synthesis including scalability, reproducibility, and lower hazardous waste burden.

Perspectives on Sharing Models and Related Resources in Computational Biomechanics Research.

The role of computational modeling for biomechanics research and related clinical care will be increasingly prominent. The biomechanics community has been developing computational models routinely for exploration of the mechanics and mechanobiology of diverse biological structures. As a result, a large array of models, data, and discipline-specific simulation software has emerged to support endeavors in computational biomechanics. Sharing computational models and related data and simulation software has first become a utilitarian interest, and now, it is a necessity. Exchange of models, in support of knowledge exchange provided by scholarly publishing, has important implications. Specifically, model sharing can facilitate assessment of reproducibility in computational biomechanics and can provide an opportunity for repurposing and reuse, and a venue for medical training. The community's desire to investigate biological and biomechanical phenomena crossing multiple systems, scales, and physical domains, also motivates sharing of modeling resources as blending of models developed by domain experts will be a required step for comprehensive simulation studies as well as the enhancement of their rigor and reproducibility. The goal of this paper is to understand current perspectives in the biomechanics community for the sharing of computational models and related resources. Opinions on opportunities, challenges, and pathways to model sharing, particularly as part of the scholarly publishing workflow, were sought. A group of journal editors and a handful of investigators active in computational biomechanics were approached to collect short opinion pieces as a part of a larger effort of the IEEE EMBS Computational Biology and the Physiome Technical Committee to address model reproducibility through publications. A synthesis of these opinion pieces indicates that the community recognizes the necessity and usefulness of model sharing. There is a strong will to facilitate model sharing, and there are corresponding initiatives by the scientific journals. Outside the publishing enterprise, infrastructure to facilitate model sharing in biomechanics exists, and simulation software developers are interested in accommodating the community's needs for sharing of modeling resources. Encouragement for the use of standardized markups, concerns related to quality assurance, acknowledgement of increased burden, and importance of stewardship of resources are noted. In the short-term, it is advisable that the community builds upon recent strategies and experiments with new pathways for continued demonstration of model sharing, its promotion, and its utility. Nonetheless, the need for a long-term strategy to unify approaches in sharing computational models and related resources is acknowledged. Development of a sustainable platform supported by a culture of open model sharing will likely evolve through continued and inclusive discussions bringing all stakeholders at the table, e.g., by possibly establishing a consortium.

O2 Plasma Etching and Antistatic Gun Surface Modifications for CNT Yarn Microelectrode Improve Sensitivity and Antifouling Properties.

Carbon nanotube (CNT) based microelectrodes exhibit rapid and selective detection of neurotransmitters. While different fabrication strategies and geometries of CNT microelectrodes have been characterized, relatively little research has investigated ways to selectively enhance their electrochemical properties. In this work, we introduce two simple, reproducible, low-cost, and efficient surface modification methods for carbon nanotube yarn microelectrodes (CNTYMEs): O2 plasma etching and antistatic gun treatment. O2 plasma etching was performed by a microwave plasma system with oxygen gas flow and the optimized time for treatment was 1 min. The antistatic gun treatment flows ions by the electrode surface; two triggers of the antistatic gun was the optimized number on the CNTYME surface. Current for dopamine at CNTYMEs increased 3-fold after O2 plasma etching and 4-fold after antistatic gun treatment. When the two treatments were combined, the current increased 12-fold, showing the two effects are due to independent mechanisms that tune the surface properties. O2 plasma etching increased the sensitivity due to increased surface oxygen content but did not affect surface roughness while the antistatic gun treatment increased surface roughness but not oxygen content. The effect of tissue fouling on CNT yarns was studied for the first time, and the relatively hydrophilic surface after O2 plasma etching provided better resistance to fouling than unmodified or antistatic gun treated CNTYMEs. Overall, O2 plasma etching and antistatic gun treatment improve the sensitivity of CNTYMEs by different mechanisms, providing the possibility to tune the CNTYME surface and enhance sensitivity.

Mechanical signals promote osteogenic fate through a primary cilia-mediated mechanism.

It has long been suspected, but never directly shown, that bone formed to accommodate an increase in mechanical loading is related to the creation of osteoblasts from skeletal stem cells. Indeed, biophysical stimuli potently regulate osteogenic lineage commitmentin vitro In this study, we transplanted bone marrow cells expressing green fluorescent protein, to enable lineage tracing, and subjected mice to a biophysical stimulus, to elicit a bone-forming response. We detected cells derived from transplanted progenitors embedded within the bone matrix near active bone-forming surfaces in response to loading, demonstrating for the first time, that mechanical signals enhance the homing and attachment of bone marrow cells to bone surfaces and the commitment to an osteogenic lineage of these cellsin vivo Furthermore, we used an inducible Cre/Lox recombination system to delete kinesin family member 3A (Kif3a), a gene that is essential for primary cilia formation, at will in transplanted cells and their progeny, regardless of which tissue may have incorporated them. Disruption of the mechanosensing organelle, the primary cilium in a progenitor population, significantly decreased the amount of bone formed in response to mechanical stimulation. The collective results of our study directly demonstrate that, in a novel experimental stem cell mechanobiology model, mechanical signals enhance osteogenic lineage commitmentin vivoand that the primary cilium contributes to this process.-Chen, J. C., Hoey, D. A., Chua, M., Bellon, R., Jacobs, C. R. Mechanical signals promote osteogenic fate through a primary cilia-mediated mechanism.

Carbon Nanotubes Grown on Metal Microelectrodes for the Detection of Dopamine.

Microelectrodes modified with carbon nanotubes (CNTs) are useful for the detection of neurotransmitters because the CNTs enhance sensitivity and have electrocatalytic effects. CNTs can be grown on carbon fiber microelectrodes (CFMEs) but the intrinsic electrochemical activity of carbon fibers makes evaluating the effect of CNT enhancement difficult. Metal wires are highly conductive and many metals have no intrinsic electrochemical activity for dopamine, so we investigated CNTs grown on metal wires as microelectrodes for neurotransmitter detection. In this work, we successfully grew CNTs on niobium substrates for the first time. Instead of planar metal surfaces, metal wires with a diameter of only 25 µm were used as CNT substrates; these have potential in tissue applications due to their minimal tissue damage and high spatial resolution. Scanning electron microscopy shows that aligned CNTs are grown on metal wires after chemical vapor deposition. By use of fast-scan cyclic voltammetry, CNT-coated niobium (CNT-Nb) microelectrodes exhibit higher sensitivity and lower ΔEp value compared to CNTs grown on carbon fibers or other metal wires. The limit of detection for dopamine at CNT-Nb microelectrodes is 11 ± 1 nM, which is approximately 2-fold lower than that of bare CFMEs. Adsorption processes were modeled with a Langmuir isotherm, and detection of other neurochemicals was also characterized, including ascorbic acid, 3,4-dihydroxyphenylacetic acid, serotonin, adenosine, and histamine. CNT-Nb microelectrodes were used to monitor stimulated dopamine release in anesthetized rats with high sensitivity. This study demonstrates that CNT-grown metal microelectrodes, especially CNTs grown on Nb microelectrodes, are useful for monitoring neurotransmitters.