Impact of implementing a fast-track protocol and standardized guideline for the management of pediatric appendicitis.

Background: In 2017, a provincial guideline was created to fast track and standardize care for pediatric appendicitis in Alberta. We conducted a study to determine the impact of implementation of the guideline at our institution on length of stay (LOS), antibiotic stewardship efforts and costs. Methods: We performed a retrospective review of the charts of all patients younger than 18 years of age who underwent appendectomy at our institution in 2 periods: before guideline implementation (Dec. 1, 2016, to May 31, 2017) and after implementation (Dec. 1, 2017, to May 31, 2018). We compared LOS, duration of antibiotic therapy, 30-day postdischarge complication rates and variable cost between the 2 cohorts. Results: Of the 276 total appendectomy procedures performed, 185 were for simple appendicitis (81 before guideline implementation and 104 after implementation), and 91 were for complicated appendicitis (44 and 47, respectively). The median LOS was shorter in the postimplementation cohort for both simple and complicated appendicitis (15.5 h [interquartile range (IQR) 12-19 h] v. 17.0 h [IQR 13-22 h], p = 0.03; and 3.0 d [IQR 2-4 d] v. 3.0 d [IQR 3-5 d], p = 0.05, respectively). Patients with complicated appendicitis had fewer antibiotic days after guideline implementation; the difference was statistically significant for patients without diffuse peritoneal contamination or abscess formation (p = 0.02). There were no differences between the cohorts with respect to 30-day rates of complications, including emergency department visits, readmission and surgical site infections. After guideline implementation, the average variable cost per patient was reduced by $230, equating to a total average annual cost savings of $75 842 for our institution. Conclusion: The implementation of a provincial guideline aimed at standardizing care in pediatric appendicitis at our institution was associated with shortened LOS, improved antibiotic stewardship efforts and reduced cost of care. Other institutions may replicate our model of a standardized pathway in the management of pediatric appendicitis in an effort to improve the quality of patient care and reduce health care costs.

Contexte: En 2017, des lignes directrices provinciales ont vu le jour en Alberta afin d'accélérer et de normaliser les soins pédiatriques pour appendicite. Notre étude visait à déterminer l'effet de leur application, par notre établissement, sur la durée du séjour, la gestion des antibiotiques et les coûts des soins. Méthodes: Nous avons examiné de façon rétrospective le dossier de tous les patients de moins de 18 ans ayant subi une appendicectomie à notre établissement avant l'application des lignes directrices (entre le 1er décembre 2016 et le 31 mai 2017) et après (entre le 1er décembre 2017 et le 31 mai 2018). Les données relatives à la durée du séjour, à la durée de l'antibiothérapie, au taux de complications 30 jours après le congé et aux coûts variables ont été comparées entre les 2 groupes. Résultats: Des 276 appendicectomies totales effectuées, 185 concernaient une appendicite simple (81 avant l'application des lignes directrices et 104 après), et 91, une appendicite compliquée (44 avant l'application et 47 après). La durée médiane du séjour était plus courte dans le groupe postapplication, tant pour l'appendicite simple (15,5 h [écart interquartile (EI) 12­19 h] c. 17,0 h [EI 13­22 h]; p = 0,03) que pour l'appendicite compliquée (3,0 j [EI 2­4 j] c. 3,0 j [EI 3­5 j]; p = 0,05). Les patients qui présentaient une appendicite compliquée avaient une antibiothérapie moins longue après l'application des lignes directrices; la différence était statistiquement significative chez les patients sans contamination péritonéale diffuse ou abcès (p = 0,02). Aucune différence n'a été observée entre les cohortes en ce qui a trait au taux de complications à 30 jours, qui comprenait les consultations à l'urgence, les réadmissions et les infections du site opératoire. L'application des lignes directrices a permis de réduire les coûts variables par patient de 230 $, ce qui représente une économie annuelle moyenne de 75 842 $ pour notre établissement. Conclusion: L'application des lignes directrices provinciales visant à normaliser les soins pédiatriques pour appendicite a été associée, dans notre établissement, à une réduction de la durée du séjour, à l'amélioration de la gestion des antibiotiques et à une diminution des coûts des soins. D'autres établissements pourraient reproduire ce modèle de soins normalisés pour améliorer la qualité et réduire les coûts.

The complex interplay between neutrophils and cancer.

Neutrophils are the most abundant type of white blood cell, and are an essential component of the innate immune system. They characteristically arrive rapidly at sites of infection and injury, and release a variety of cytokines and toxic molecules to eliminate pathogens and elicit an acute inflammatory response. Research into the function of neutrophils in cancer suggest they have divergent roles. Indeed, while most studies have found neutrophils to be associated with cancer progression, others have also documented anticancer effects. In this review, we describe the investigations into neutrophil populations that have been implicated in promoting tumor growth and metastasis as well those demonstrating antitumor functions. The collective research suggests a complex role for neutrophils in cancer biology, which raises the prospect of their targeting for the treatment of cancer.

Unusual case of coronal complete bladder duplication associated with rectoprostatic fistula to duplicated prostatic urethra.

Anorectal malformations are a common congenital anomaly, while bladder duplication is rare. Bladder duplications are classified as complete or incomplete and sagittal or coronal. We present a rare case of coronal complete bladder duplication with rectoprostatic fistula to the blind ending prostatic urethra of the duplicated bladder.

A Pilot Study on the Utility of Serum Metabolomics in Neuroblastoma Patients and Xenograft Models.

BACKGROUND: Improved prediction of neuroblastoma (NB) behavior is needed to detect treatment-refractory disease and may allow further reduction in therapy for some patients. In this regard, serum metabolomic analysis has proven utility in several cancer types. We hypothesize that serum metabolomic analysis will correlate with risk-group classification for patients with NB, and sensitively detect NB in murine xenograft models. PROCEDURE: A pilot study was done on Children's Oncology Group (COG) tumor bank sera from 10 patients (five high-, five low-risk). An institutional pilot study was carried out on five patients comparing sera obtained during active versus minimal disease (complete response/very good partial response; CR/VGPR). XENOGRAFT: Flank tumors were established in Nu/Nu mice by injection of NB cell lines (IMR-32, SH-EP, SK-N-AS). Serum for comparison was drawn pre-injection, at 1 week after injection when there was no visible tumor, and again once tumors were grossly visible. Comparisons were also made between tumor bearing mouse serum and supernatants from NB cell lines. METABOLOMIC ANALYSIS: Samples were analyzed by nuclear magnetic resonance and/or gas chromatography-mass spectrometry. Multivariate data analysis was conducted using SIMCA-P (Umetrics). RESULTS: Serum metabolomic analysis differentiated high- and low-risk patients as well as active disease from CR/VGPR. Differences were in nitrogen, amino acid, and carbohydrate metabolism, as well as ketosis. The serum metabolomic signature in murine xenograft models sensitively detected NB cells and correlated with disease burden. Similar metabolic changes attributable to NB were noted in both human and murine serum. CONCLUSIONS: Serum metabolomic analysis can distinguish several characteristics of NB. A larger analysis of COG banked sera is warranted.

Antireflux Procedures in Children With Neurologic Impairment: A National Survey of Physician Perspectives.

OBJECTIVE: Decision-making about antireflux procedures (ARPs) to treat gastroesophageal reflux disease in children with neurologic impairment and gastrostomy tubes is challenging and likely influenced by physicians' experience and perspectives. This study will explore physician attitudes about ARPs and determine if there are relationships to clinical practice and personal characteristics. METHODS: This is a national observational cross-sectional study that used an electronic questionnaire addressing reported practice, attitudes regarding the ARPs, and responses to clinical vignettes. Participants were physicians in Canadian tertiary-care pediatric settings. Descriptive statistics were used to analyze physician attitudes. Multivariable logistic regression modeling was used to determine associations between physician and practice characteristics and likelihood to consider ARP. RESULTS: Eighty three respondents represented 12 institutions, with a majority from general or complex care pediatrics. There was a wide disparity between likelihood to consider ARP in each clinical scenario. Likelihood to consider ARP ranged from to 19% to 78% depending on the scenario. Two scenarios were equally split in whether the respondent would offer an ARP. None of the demographic characteristics were significantly associated with likelihood to consider ARP. Often, gastrojejunostomy tubes alone were considered (56% to 68%). CONCLUSIONS: There is considerable variability in physician attitudes toward and recommendations regarding ARPs to treat gastroesophageal reflux disease. We did not find a significant association with clinical experience or location of practice. More research is needed to define indications and outcomes for ARPs. This is a scenario where shared decision-making, bringing together physician and family knowledge and expertise, is likely the best course of action.

Circulating endothelial progenitor cells are up-regulated in a mouse model of endometriosis.

Endometriosis is a debilitating disease characterized by the growth of ectopic endometrial tissue. It is widely accepted that angiogenesis plays an integral part in the establishment and growth of endometriotic lesions. Recent data from a variety of angiogenesis-dependent diseases suggest a critical role of bone marrow-derived endothelial progenitor cells (EPCs) in neovascularization. In this study we examined the blood levels of EPCs and mature circulating endothelial cells in a mouse model of surgically induced endometriosis. Fluorescence-activated cell sorting analysis revealed elevated levels of EPCs in the blood of mice with endometriosis compared with control subject that underwent a sham operation. EPC concentrations positively correlated with the amount of endometriotic tissue and peaked 1 to 4 days after induction of disease. In a green fluorescent protein bone marrow transplant experiment we found green fluorescent protein-positive endothelial cells incorporated into endometriotic lesions but not eutopic endometrium, as revealed by flow cytometry and immunohistochemistry. Finally, treatment of endometriosis-bearing mice with the angiogenesis inhibitor Lodamin, an oral nontoxic formulation of TNP-470, significantly decreased EPC levels while suppressing lesion growth. Taken together, our data indicate an important role for bone marrow-derived endothelial cells in the pathogenesis of endometriosis and support the potential clinical use of anti-angiogenic therapy as a novel treatment modality for this disease.

Developing implementation strategies to adopt Enhanced Recovery After Surgery (ERAS®) guidelines.

BACKGROUND: Strong implementation strategies are critical to the success of Enhanced Recovery after Surgery (ERAS®) guidelines, though little documentation exists on effective strategies, especially in complex clinical situations and unfamiliar contexts. This study outlines the process taken to adopt a novel neonatal ERAS® guideline. METHODS: The implementation strategy was approached in a multi-pronged, concurrent but asynchronous fashion. Between September 2019 and January 2020, healthcare providers from various disciplines and different specialties as well as parents participated in the strategy. Multidisciplinary teams were created to consider existing literature and local contexts including potential facilitators and/or barriers. Task forces worked collaboratively to develop new care pathways. An audit system was developed to record outcomes and elicit feedback for revision. RESULTS: 32 healthcare providers representing 9 disciplines and 5 specialties as well as 8 parents participated. Care pathways and resources were created. Elements recommended for a successful implementation strategy included identification of champions, multidisciplinary stakeholder involvement, consideration of local contexts and insights, patient/family engagement, education, and creation of an audit system. CONCLUSION: A multidisciplinary and structured process following principles of implementation science was used to develop an effective implementation strategy for initiating ERAS® guidelines.

Potent antitumor effects of ZD6474 on neuroblastoma via dual targeting of tumor cells and tumor endothelium.

Among children with relapsed or refractory neuroblastoma, the prognosis is poor and novel therapeutic strategies are needed to improve long-term survival. As with other solid tumors, high vascular density within neuroblastoma is associated with advanced disease, and therapeutic regimens directed against the tumor vasculature may provide clinical benefit. The receptor tyrosine kinase RET is widely expressed in neuroblastoma and is known to activate key signal transduction pathways involved in tumor cell survival and progression including Ras/mitogen-activated protein kinase and phosphatidylinositol 3-kinase/Akt. We investigated the effect of dual targeting of tumor cells and tumor endothelium with ZD6474, a small-molecule tyrosine kinase inhibitor of vascular endothelial growth factor (VEGF) receptor 2, epidermal growth factor receptor, and RET. ZD6474 inhibited the phosphorylation of RET in neuroblastoma cells and had a direct effect on tumor cell viability in seven neuroblastoma cell lines. In a human neuroblastoma xenograft model, ZD6474 inhibited tumor growth by 85% compared with treatment with vehicle alone. In contrast, no significant inhibition of tumor growth was observed after treatment with bevacizumab, an antihuman VEGF monoclonal antibody, or the epidermal growth factor receptor inhibitor erlotinib, either alone or in combination. Immunohistochemical analysis showed that ZD6474 treatment led to an increase in endothelial cell apoptosis along with inhibition of VEGF receptor-2 activation on tumor endothelium. In conclusion, dual targeting of tumor cells, potentially through RET inhibition, and tumor vasculature with ZD6474 leads to potent antitumor effects. This approach merits further investigation for patients with neuroblastoma.

Blood-based biomarkers of SU11248 activity and clinical outcome in patients with metastatic imatinib-resistant gastrointestinal stromal tumor.

PURPOSE: There is an unmet need for noninvasive markers to measure the biological effects of targeted agents, particularly those inhibiting the vascular endothelial growth factor (VEGF) receptor (VEGFR) pathway, and identify patients most likely to benefit from treatment. In this study, we investigated potential blood-based biomarkers for SU11248 (sunitinib malate), a multitargeted tyrosine kinase inhibitor, in patients with metastatic imatinib-refractory gastrointestinal stromal tumors. EXPERIMENTAL DESIGN: Patients (n=73) enrolled in a phase I/II trial received SU11248 daily for 14 or 28 days followed by 14 days without treatment per cycle. Clinical benefit was defined as progression-free survival of >6 months. We assessed plasma markers, including VEGF and soluble VEGFR-2 (sVEGFR-2), and two cellular populations bearing VEGF receptors: monocytes and, in a subset of patients, mature circulating endothelial cells (CEC). RESULTS: Compared to patients with progressive disease, patients with clinical benefit had significantly greater increases in CECs (0.52 versus -0.01 CEC/microL/d, P=0.03) and smaller decreases in monocyte levels (47% versus 60%, P=0.007) during cycle 1. VEGF increased by 2.2-fold and sVEGFR-2 decreased 25% during the first 2 weeks of treatment. Neither plasma marker correlated with clinical outcome although a modest inverse correlation was observed between sVEGFR-2 changes and plasma drug levels. Monocytes, VEGF, and sVEGFR-2 all rebounded towards baseline off treatment. CONCLUSIONS: Monocytes, VEGF, and sVEGFR-2 were consistently modulated by treatment, suggesting that they may serve as pharmacodynamic markers for SU11248. Changes in CECs and monocytes, but not the plasma markers, differed between the patients with clinical benefit and those with progressive disease. These end points merit further investigation in future trials to determine their utility as markers of SU11248 activity and clinical benefit in gastrointestinal stromal tumors and other tumor types.

Probiotics supplementation and length of hospital stay in neonates with gastrointestinal surgery.

Any manipulation on open bowel causes interventional impact on gut microbiome, and surgical stress triggers bacterial translocation; thus, it will be fundamental to determine gut microbiome after surgery. Monitoring dynamic changes in microbiome of post-surgical infants who received probiotics and placebo could provide with important information about gut colonization and potential bacterial overgrowth. The purpose of this study is to assess the effect of probiotics supplementation on length of hospital stay, duration of parenteral nutrition, and feed tolerance in neonates after gastrointestinal surgery.

Differential effects of vascular endothelial growth factor receptor-2 inhibitor ZD6474 on circulating endothelial progenitors and mature circulating endothelial cells: implications for use as a surrogate marker of antiangiogenic activity.

PURPOSE: Circulating endothelial cells (CEC) comprise at least two distinct populations: bone marrow-derived circulating endothelial progenitors (CEP) and mature CECs derived from existing vasculature. We hypothesized that antiangiogenic agents may have differential effects on CEPs and mature CECs and that these changes may serve as a marker of biological activity. EXPERIMENTAL DESIGN: The effect of angiogenesis inhibitors on CECs was evaluated by flow cytometry after vascular endothelial growth factor (VEGF)-induced mobilization and in mice bearing Lewis lung carcinoma (LLC). Tumor angiogenesis was evaluated in parallel by immunohistochemistry. RESULTS: In nontumor-bearing mice, VEGF administration increased both mature CECs and CEPs. This increase was inhibited by the VEGF receptor 2 inhibitor ZD6474 as well as the VEGF inhibitor-soluble Flt-1. ZD6474 had no significant effect on CECs in the absence of exogenous VEGF stimulation. In contrast, LLC-bearing mice had an increase in mature CECs but not CEPs after 3 days of treatment with ZD6474. The increase in mature CECs was dose-dependent, accompanied by a decrease in tumor microvessel density, and preceded reduction in tumor volume. Treatment of LLC-bearing mice with the vascular targeting agent ZD6126 also increased mature CECs. CONCLUSIONS: VEGF inhibitors can have differential effects on mature CECs and CEPs, and agents inhibiting tumor angiogenesis may cause a concomitant increase in mature CECs. This increase occurs in tumor-bearing but not in nontumor-bearing mice, suggesting that tumor endothelium is a potential source of mature CECs. Therefore, assessing both mature CECs and CEPs may provide insights into the mechanism of antiangiogenic agents and serve as an early surrogate marker of biological activity.

N-Myc expression enhances the oncolytic effects of vesicular stomatitis virus in human neuroblastoma cells.

N-myc oncogene amplification is associated but not present in all cases of high-risk neuroblastoma (NB). Since oncogene expression could often modulate sensitivity to oncolytic viruses, we wanted to examine if N-myc expression status would determine virotherapy efficacy to high-risk NB. We showed that induction of exogenous N-myc in a non-N-myc-amplified cell line background (TET-21N) increased susceptibility to oncolytic vesicular stomatitis virus (mutant VSVΔM51) and alleviated the type I IFN-induced antiviral state. Cells with basal N-myc, on the other hand, were less susceptible to virus-induced oncolysis and established a robust IFN-mediated antiviral state. The same effects were also observed in NB cell lines with and without N-myc amplification. Microarray analysis showed that N-myc overexpression in TET-21N cells downregulated IFN-stimulated genes (ISGs) with known antiviral functions. Furthermore, virus infection caused significant changes in global gene expression in TET-21N cells overexpressing N-myc. Such changes involved ISGs with various functions. Therefore, the present study showed that augmented susceptibility to VSVΔM51 by N-myc at least involves downregulation of ISGs with antiviral functions and alleviation of the IFN-stimulated antiviral state. Our studies suggest the potential utility of N-myc amplification/overexpression as a predictive biomarker of virotherapy response for high-risk NB using IFN-sensitive oncolytic viruses.

Congenital Bands with Intestinal Malrotation after Propylthiouracil Exposure in Early Pregnancy.

Exposure to propylthiouracil in early pregnancy may be associated with an increased risk of birth defects. But the spectrum of associated congenital anomalies is not yet well defined. While preliminary reports suggest that most cases of propylthiouracil-associated birth defects are restricted to the preauricular and urinary systems, careful consideration should be given to other possible manifestations of teratogenicity. We propose that congenital bands may potentially represent a rare yet serious complication of propylthiouracil exposure in early pregnancy, possibly arising from an early mesenteric developmental anomaly. We report a case of a 17-day-old girl that presented with acute small bowel obstruction associated with intestinal malrotation arising from several anomalous congenital bands. Her mother was treated for Graves' disease during pregnancy with first trimester exposure to propylthiouracil but remained clinically and biochemically euthyroid at conception and throughout the duration of pregnancy. This case suggests that the use of propylthiouracil in early pregnancy may be associated with congenital bands and intestinal malrotation. More reports are needed to further support this association.

Intestinal thromboangiitis obliterans in a woman: a case report and discussion of chronic ischemic changes.

Although traditionally regarded as a disease of distal extremities, mesenteric vasculature can also manifest thromboangiitis obliterans (TAO). There are 31 cases of intestinal TAO in the English literature and the majority of subjects are male. However, cases of women with TAO are becoming more common, coinciding with an increased incidence of smoking in this sex. We describe the sixth case of a female patient with classic extremity manifestations paralleled by paroxysms of abdominal angina. Intestinal TAO can mimic extremity disease of smoldering chronic ischemia punctuated by unpredictable acute episodes of gangrene. In the present case, chronic ischemia manifested as partial bowel obstruction due to stricture deformity of the ileum and profound adipocyte atrophy of mesentery.

Traumatic pseudoaneurysms of the liver and spleen in children: is routine screening warranted?

BACKGROUND: Although blunt injury to the spleen and liver can lead to pseudoaneurysm formation, current surgical guidelines do not recommend follow-up imaging. Controversy exists regarding the clinical implications of these traumatic pseudoaneurysms as well as their management. METHODS: Retrospective review of children treated nonoperatively for isolated blunt liver and spleen trauma between 1991 and 2008 was undertaken. Patient demographics, grade of injury, and follow-up Doppler ultrasound results were obtained. RESULTS: Three hundred sixty-two children were identified. One hundred eighty-six of them had splenic injuries, and 10 (5.4%) developed pseudoaneurysms. They were associated with grade III (3/39 [8%]) and grade IV (7/41 [17%]) injuries. In 7 patients, the pseudoaneurysm thrombosed spontaneously. Angiographic embolization was required in 2 children, and one underwent emergency splenectomy for delayed hemorrhage. Of the 176 patients who had liver injuries, 3 (1.7%) developed pseudoaneurysms. All 3 were associated with grade IV injuries (3/11 [27%]). One child underwent early embolization, while 2 developed delayed hemorrhage requiring emergent treatment. CONCLUSIONS: Pseudoaneurysm development after blunt abdominal trauma is associated with high-grade splenic and liver injuries. Routine screening of this group of patients before discharge from hospital may be warranted because of the potential risk of life-threatening hemorrhage.

A multiinstitutional review of central venous line complications: retained intravascular fragments.

BACKGROUND: There have been many reports of complications of central venous lines in children but limited discussion of the specific problem of retained intravascular fragments after attempted removal. We report on a series of 6 patients from 2 tertiary pediatric hospitals that had intravascular segments of long-term central venous lines that could not be removed and so were left in situ. METHODS: We conducted a retrospective multiinstitutional review of long-term central venous lines (Broviacs, Port-A-Caths, and Hickmans) removed in the operating room with a focused chart review and prospective follow-up of those patients that had a failed attempt at removal. RESULTS: A total of 299 central venous lines were removed with 6 patients identified as having fragments of lines left behind (2%). The lines had been in place for an average of 37 +/- 12 months. The average follow-up period is now 5.4 +/- 3.9 years; none of the patients have developed any symptoms, evidence of thrombus, infection, or catheter migration. CONCLUSION: Given the 2% incidence rate, the issue of managing a stuck long-term central venous line will face most individuals who place these lines. We have demonstrated that simply ligating the catheter and leaving the fragment in place appears to be a safe option with minimal risk to the patient.

Case selection in minimally invasive surgical treatment of neuroblastoma.

PURPOSE: The experience with minimally invasive surgery (MIS) in the treatment of neuroblastoma (NB) is anecdotal. The purpose of this study was to evaluate a retrospective cohort of NB patients who underwent MIS resection of their primary tumors. METHODS: A retrospective study of NB patients who underwent MIS resection of their primary tumors over a 3-year period was undertaken. Study outcomes included complications, completeness of resection, and event-free and overall short-term survival. RESULTS: Of a total of 21 children who underwent surgical resection for NB during the period of study, 8 (38%) underwent selected MIS resection. Six of the eight (75%) tumors were adrenal in origin and the remainder were located in the posterior mediastinum. Distribution by International Neuroblastoma Staging System (INSS) stage was: stage 1 (3), stage 2 (2), and stage 4 (3). One stage 4 tumor was N-myc amplified. All stage 4 patients experienced a >50% tumor volume cytoreduction in response to preoperative chemotherapy. All MIS resections were performed without need for blood transfusion, or conversion to open procedure, and there were no perioperative complications. All eight patients were alive and disease-free at a median 18-month follow-up. CONCLUSIONS: With appropriate preoperative case selection based on anatomic features, MIS tumor resection in patients with NB can be performed safely and effectively.

Endothelial progenitor cells contribute to accelerated liver regeneration.

Two classes of circulating endothelial cells (CECs) have been identified and are distinguished by the expression of the stem cell markers CD117 or CD133 together with endothelial-specific antigens. Stem cell marker-positive CECs originate from bone marrow and have been designated as circulating endothelial progenitors (CEPs). We have demonstrated that exogenous vascular endothelial growth factor (VEGF) effectively mobilizes CEP cells. Furthermore, it has been demonstrated that VEGF regulates liver regeneration after partial hepatectomy. Although local endothelial cells can regulate tissue mass during liver regeneration, the contribution of CEPs to this process is unknown. We discovered loss of CD117 and CD133 from murine CEP cells and that both markers underestimated the number of bone marrow-derived CEP cells. We therefore used wild type and green fluorescent protein (GFP)-bone marrow transplanted into wild-type mice and performed 70% hepatectomies. Furthermore, we found that treatment with exogenous VEGF accelerated liver regeneration after 70% hepatectomy, whereas immunohistochemical analysis showed a 7-fold increase in the incorporation of CEP cells into liver vasculature. These results suggest that CEP cells play a role in regulating liver regeneration and that VEGF treatment can mobilize CEP cells to accelerate this process.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and inflammatory stimuli up-regulate secretion of the soluble GM-CSF receptor in human monocytes: evidence for ectodomain shedding of the cell surface GM-CSF receptor alpha subunit.

Soluble GM-CSF receptor alpha subunit (sGMRalpha) is a soluble isoform of the GMRalpha that is believed to arise exclusively through alternative splicing of the GMRalpha gene product. The sGMRalpha mRNA is expressed in a variety of tissues, but it is not clear which cells are capable of secreting the protein. We show here that normal human monocytes, but not lymphocytes, constitutively secrete sGMRalpha. Stimulation of monocytes with GM-CSF, LPS, PMA, or A23187 rapidly up-regulates the secretion of sGMRalpha in a dose-dependent manner, demonstrating that secretion is also regulated. To determine whether sGMRalpha arose exclusively through alternative splicing of the GMRalpha gene product, or whether it could also be generated through ectodomain shedding of GMRalpha, we engineered a murine pro-B cell line (Ba/F3) to express exclusively the cDNA for cell surface GMRalpha (Ba/F3.GMRalpha). The Ba/F3.GMRalpha cell line, but not the parental Ba/F3 cell line, constitutively shed a sGMRalpha-like protein that bound specifically to GM-CSF, was equivalent in size to recombinant alternatively spliced sGMRalpha (60 kDa), and was recognized specifically by a mAb raised against the ectodomain of GMRalpha. Furthermore, a broad-spectrum metalloprotease inhibitor (BB94) reduced constitutive and PMA-, A23187-, and LPS-induced secretion of sGMRalpha by monocytes, suggesting that shedding of GMRalpha by monocytes may be mediated in part through the activity of metalloproteases. Taken together, these observations demonstrate that sGMRalpha is constitutively secreted by monocytes, that GM-CSF and inflammatory mediators up-regulate sGMRalpha secretion, and that sGMRalpha arises not only through alternative splicing but also through ectodomain shedding of cell surface GMRalpha.