Pediatric Surgery Collaboration in Uganda, the Benefits of Long Term Partnerships at Regional Referral Hospitals.

Background: In 2022 there were only seven pediatric surgeons in Uganda, but approximately 170 are needed. Consequently, Ugandan general surgeons treat most pediatric surgical problems at regional hospitals. Accordingly, stakeholders created the Pediatric Emergency Surgery Course, which teaches rural providers identification, resuscitation, treatment and referral of pediatric surgical conditions. In order to improve course offerings and better understand pediatric surgery needs we collected admission and operative logbook data from four participating sites. One participating site, Lacor Hospital, rarely referred patients and had a much higher operative volume. Therefore, we sought to understand the causes of this difference and the resulting economic impact. Methods: Over a four-year period, data was collected from logbooks at four different regional referral hospitals in Uganda. Patients ≤ 18 years old with a surgical diagnosis were included. Patient LOS, referral volume, age, and case type were compared between sites and DALYs were calculated and converted into monetary benefit. Results: Over four sites, 8,615 admissions, and 5,457 cases were included. Lacor patients were younger, had a longer length of stay, and were referred less. Additionally, Lacor's long-term partnerships with a high-income country institution, a missionary organization, and visiting Ugandan and international pediatric surgeons were unique. In 2018, the pediatric surgery case volume was: Lacor (967); Fort Portal (477); Kiwoko (393); and Kabale (153), resulting in a substantial difference in long-term monetary health benefit. Conclusion: Long-term international partnerships may advance investments in surgical infrastructure, workforce, and education in low- and middle-income countries. This collaborative model allows stakeholders to make a greater impact than any single institution could make alone.

Pediatric Emergency Surgery Course in Uganda: Long-Term Follow-Up and Insights From Further Dissemination.

INTRODUCTION: Approximately 170 pediatric surgeons are needed for the 24 million children in Uganda. There are only seven. Consequently, general surgeons manage many pediatric surgical conditions. In response, stakeholders created the Pediatric Emergency Surgery Course (PESC) for rural providers, given three times in 2018-2019. We sought to understand the course's long-term impact, current pediatric surgery needs, and determine measures for improvement. METHODS: In October 2021, we distributed the same test given in 2018-2019. Student's t-test was used to compare former participants' scores to previous scores. The course was delivered again in May 2022 to new participants. We performed a quantitative needs assessment and also conducted a focus group with these participants. Finally, we interviewed Surgeon in Chiefs at previous sites. RESULTS: Twenty three of the prior 45 course participants re-took the PESC course assessment. Alumni scored on average 71.9% ± 18% correct. This was higher from prior precourse test scores of 55.4% ± 22.4%, and almost identical to the 2018-2019 postcourse scores 71.9% ± 14%. Fifteen course participants completed the needs assessment. Participants had low confidence managing pediatric surgical disease (median Likert scale ≤ 3.0), 12 of 15 participants endorsed lack of equipment, and eight of 15 desired more educational resources. Qualitative feedback was positive: participants valued the pragmatic lessons and networking with in-country specialists. Further training was suggested, and Chiefs noted the need for more trained staff like anesthesiologists. CONCLUSIONS: Participants favorably reviewed PESC and retained knowledge over three years later. Given participants' interest in more training, further investment in locally derived educational efforts must be prioritized.

The Pediatric Emergency Surgery Course: Impact on Provider Practice in Rural Uganda.

PURPOSE: The Pediatric Emergency Surgery Course (PESC) trains rural Ugandan providers to recognize and manage critical pediatric surgical conditions. 45 providers took PESC between 2018 and 2019. We sought to assess the impact of the course at three regional hospitals: Fort Portal, Kabale, and Kiwoko. METHODS: We conducted a retrospective cohort study. Diagnosis, procedure, and patient outcome data were collected twelve months before and after PESC from admission and theater logbooks. We also assessed referrals from these institutions to Uganda's two pediatric surgery hubs: Mulago and Mbarara Hospitals. Wilcoxon rank-sum and Pearson's chi-squared tests compared pre- and post-PESC measures. Interrupted time-series-analysis assessed referral volume before and after PESC. RESULTS: 1534 admissions and 2148 cases were documented across the three regional hospitals. Kiwoko made 539 referrals, while pediatric surgery hubs received 116 referrals. There was a statistically significant immediate increase in the number of referrals from Fort Portal, from 0.5 patients/month pre-PESC to 0.8 post-PESC (95 % CI 0.03-1.51). Moving averages of the combined number of pyloromyotomy, intussusception reductions, and hernia repairs at the rural hospitals also increased post-course. Neonatal time to referral and referred patient age were significantly lower after PESC delivery. CONCLUSION: Our data suggest that PESC increased referrals to tertiary centers and operative volume of selected cases at rural hospitals and shortened time to presentation at sites receiving referrals. PESC is a locally-driven, validated, clinical education intervention that improves timely care of pediatric surgical emergencies and merits further support and dissemination. TYPE OF STUDY: Retrospective Cohort Study. LEVEL OF EVIDENCE: III.

The Creation of a Pediatric Surgical Checklist for Adult Providers.

Purpose: To address the need for a pediatric surgical checklist for adult providers. Background: Pediatric surgery is unique due to the specific needs and many tasks that are employed in the care of adults require accommodations for children. There are some resources for adult surgeons to perform safe pediatric surgery and to assist such surgeons in pediatric emergencies, we created a straightforward checklist based on current literature. We propose a surgical checklist as the value of surgical checklists has been validated through research in a variety of applications. Methods: Literature review on PubMed to gather information on current resources for pediatric surgery, all papers on surgical checklists describing their outcomes as of October 2022 were included to prevent a biased overview of the existing literature. Interviews with multiple pediatric surgeons were conducted for the creation of a checklist that is relevant to the field and has limited bias. Results: 42 papers with 8529061 total participants were included. The positive impact of checklists was highlighted throughout the literature in terms of outcomes, financial cost and team relationship. Certain care checkpoints emerged as vital checklist items: antibiotic administration, anesthetic considerations, intraoperative hemodynamics and postoperative resuscitation. The result was the creation of a checklist that is not substitutive for existing WHO surgery checklists but additive for adult surgeons who must operate on children in emergencies. Conclusion: The outcomes measured throughout the literature are varied and thus provide both a nuanced view of a variety of factors that must be taken into account and are limited in the amount of evidence for each outcome. We hope to implement the checklist developed to create a standard of care for pediatric surgery performed in low resource settings by adult surgeons and further evaluate its impact on emergency pediatric surgery outcomes. Funding: Fulbright Fogarty Fellowship, GHES NIH FIC D43 TW010540.

Senhance Robotic Platform in Pediatrics: Early US Experience.

INTRODUCTION: Different robotic systems have been used widely in human surgery since 2000, but pediatric patients require some features that are lacking in the most frequently used robotic systems. HYPOTHESIS: The Senhance® robotic system is a safe and an effective device for use in infants and children that has some advantages over other robotic systems. METHODS: All patients between 0 and 18 years of age whose surgery was amenable to laparoscopy were offered enrollment in this IRB-approved study. We assessed the feasibility, ease and safety of using this robotic platform in pediatric patients including: set-up time, operative time, conversions, complications and outcomes. RESULTS: Eight patients, ranging from 4 months to 17 years of age and weighing between 8 and 130 kg underwent a variety of procedures including: cholecystectomy (3), inguinal herniorrhaphy (3), orchidopexy for undescended testes (1) and exploration for a suspected enteric duplication cyst (1). All robotic procedures were successfully performed. The 4-month-old (mo), 8 kg patient underwent an uneventful robotic exploration in an attempt to locate a cyst that was hidden in the mesentery at the junction of the terminal ileum and cecum, but ultimately the patient required an anticipated laparotomy to palpate the cyst definitively and to excise it completely. There was no blood loss and no complications. Robotic manipulation with the reusable 3 mm instruments proved successful in all cases. CONCLUSIONS: Our initial experience with the Senhance® robotic platform suggests that this is a safe and effective device for pediatric surgery that is easy to use, and which warrants continued evaluation. Most importantly, there appears to be no lower age or weight restrictions to its use.

Cannabinoid Hyperemesis Syndrome Complicated by Pneumomediastinum: Implications for Pediatric Surgeons.

BACKGROUND: Cannabinoid Hyperemesis Syndrome (CHS) is a form of cyclic vomiting syndrome characterized by episodic vomiting occurring every few weeks or months and is associated with prolonged and frequent use of high-dose cannabis. CHS in the pediatric population has been increasingly reported over the last decade and can lead to life-threatening complications such as pneumomediastinum, which warrant careful consideration for surgical intervention. CASE PRESENTATION: A 17-year-old female with no significant past medical history presented to the emergency department with abdominal pain, nausea, and vomiting for 24 hours. She had four episodes of green-yellow emesis followed by dry heaves. She also complained of chest and back pain, worse with deep inspiration. Upon further history, the patient reported a similar episode of abdominal pain and repetitive vomiting six months prior to the current episode. She smoked cannabis at least once daily and has done so for the past two years. Chest X-ray revealed a subtle abnormal lucency along the anteroposterior window and anterior mediastinum, consistent with a small amount of pneumomediastinum without any other acute intrathoracic abnormalities. Follow-up chest computed tomography with contrast showed multiple foci of air within the anterior and posterior mediastinum tracking up to the thoracic inlet. There was no evidence of contrast extravasation; however, small esophageal perforation could not be excluded. Given uncomplicated pneumomediastinum without frank contrast extravasation, the patient was treated medically with piperacillin-tazobactam, metronidazole, and micafungin for microbial prophylaxis; hydromorphone for pain control; as well as with pantoprazole, ondansetron, and promethazine. Nutrition was provided via total parenteral nutrition. The patient was intensely monitored for signs of occult esophageal perforation, but none were detected. She was advanced to a soft diet on hospital day eight, solid food diet on day nine, at which point antibiotics were discontinued, and the patient was subsequently discharged. CONCLUSION: CHS in an increasingly common disorder encountered in the pediatric setting due to rising prevalence of cannabis use. The management of CHS and potentially life-threatening complications such as pneumomediastinum should be given careful consideration. Pneumomediastinum can be a harbinger of more sinister pathology such as esophageal perforation, which may warrant urgent surgical intervention.

Assessment of the da Vinci Single Port Robotic Platform on Cholecystectomy in Adolescents.

Background: The new da Vinci single port (SP) robotic platform has great appeal for pediatric surgery. To assess its efficacy and identify potential challenges, 7 adolescents underwent SP cholecystectomy. Materials and Methods: The surgeon controls three fully wristed elbowed instruments, and the first fully wristed da Vinci endoscope through a single 2.5 cm cannula. Instruments can reach 24 cm deep and triangulate distally. Instruments can also reach anatomy anywhere within 360° of port placement. A vertical incision was made through the umbilicus for port access. The cystic duct and cystic artery were dissected, clipped, divided, and hook cautery was used to remove the gallbladder. Patient characteristics and outcomes were collected and analyzed. Results: Patients were American Society of Anesthesiologists (ASA) classes I, II, and III; mean age was 17 years; mean weight was 72 kg; and 6 of 7 patients were female. There were no fatalities, and there were no returns to the operating room. Mean estimated blood loss was 2 mL and mean case duration was 126 minutes. Five out of seven patients were treated as outpatients, and none of them required narcotics on discharge. One patient reported bilateral shoulder pain 1 day postoperatively and was taking hydrocodone/acetaminophen at the time of 13-day follow-up. Conclusions: SP robotic platform cholecystectomy in adolescents appears to be safe and effective. The wristed movement of the robotic instruments improves surgeon dexterity, and the single incision hidden in the contour of the umbilicus provides good cosmesis. This series sets an exciting precedent and provides a glimpse of what is possible in pediatric robotic surgery. Clinical Trial Registration number 2014-0396.

Single port robotic splenectomy for pyruvate kinase deficiency in a five-year-old patient, a case report of a surgical first.

INTRODUCTION: Adoption of robotic surgery in pediatrics has been slow. Robotic surgery within spatially-constrained workspaces in children makes traditional platforms less translatable. Da Vinci's newest single port (SP) robotic platform provides narrow, and deep access, making pediatric robotic surgery more feasible. CASE PRESENTATION: A five-year old female presented with hepatosplenomegaly due to hemolytic anemia from pyruvate kinase deficiency (PKD). When she progressed to requiring monthly transfusions, a splenectomy was performed to avoid the complications associated with frequent blood transfusions. The robotic approach was used to remove the intact spleen because traditional minimally invasive surgery can result in post-operative splenosis. DISCUSSION: The patient successfully underwent single-port, robotic splenectomy - the first known splenectomy in a child using this approach. Furthermore, during the operation an accessory spleen was encountered in the omentum and was also successfully removed robotically. The patient tolerated the procedure well. CONCLUSION: This case demonstrates that the SP robot can be used for splenectomy to eliminate the risk of splenosis and achieve a superior cosmetic result.

How mimicry influences the neural correlates of reward: An fMRI study.

Mimicry has been suggested to function as a "social glue", a key mechanism that helps to build social rapport. It leads to increased feeling of closeness toward the mimicker as well as greater liking, suggesting close bidirectional links with reward. In recent work using eye-gaze tracking, we have demonstrated that the reward value of being mimicked, measured using a preferential looking paradigm, is directly proportional to trait empathy (Neufeld and Chakrabarti, 2016). In the current manuscript, we investigated the reward value of the act of mimicking, using a simple task manipulation that involved allowing or inhibiting spontaneous facial mimicry in response to dynamic expressions of positive emotion. We found greater reward-related neural activity in response to the condition where mimicry was allowed compared to that where mimicry was inhibited. The magnitude of this link from mimicry to reward response was positively correlated to trait empathy.

Minimizing variance in pediatric gastrostomy: does standardized perioperative feeding plan decrease cost and improve outcomes?

BACKGROUND: A protocol for laparoscopic gastrostomy placement was implemented which specified perioperative antibiotics, feeding regimens, and discharge criteria. Our hypothesis was that hospital cost could be decreased, whereas at the same time improving or maintaining patient outcomes. METHODS: Data were collected on consecutive patients beginning 6 months after implementation of our protocol. We recorded surgeon compliance, patient outcomes (as defined by 30-day NSQIP complication rates), and cost of initial hospitalization, which was then compare to a 6-month historical control period. RESULTS: Our control group n = 26 and protocol group n = 39. Length of stay was shorter in the protocol group (P ≤ .05 by nonparametric analysis). The complication rate was similar in both groups (23% control vs 15% protocol, P = .43). Initial hospital costs were not different. Surgeon compliance to protocol was 82%. CONCLUSIONS: A standard protocol is achievable for gastrostomy tube management. After implementation of our protocol, we were able to show a significant decrease in length of stay, whereas maintaining quality.

LAHRI: Laparoscopic-Assisted Hydrostatic Reduction of Intussusception.

BACKGROUND/PURPOSE: Intussusception is the most common cause of bowel obstruction in children from 3 months to 3 years of age. In the absence of peritonitis, initial treatment is either hydrostatic or pneumatic reduction. If these measures fail, operative intervention is required. In nonreducible cases, we propose the use of intraoperative hydrostatic enema to achieve or confirm reduction. In this study we describe a cohort of patients who have undergone laparoscopic-assisted hydrostatic reduction of intussusception (LAHRI). MATERIALS AND METHODS: This is a retrospective cohort study of all patients undergoing LAHRI from the years 2011 to 2013. We performed LAHRI in seven children 4 months to 2 years of age. All patients had ileocolic intussusception that failed initial reduction by radiographic enema. With the patient under general anesthesia, saline enema reduction was facilitated by direct laparoscopic visualization. RESULTS: In 2 of the 7 cases, intussusception reduction was visually confirmed in real time, and only a laparoscopic camera port was required. In 1 patient, the bowel was extensively dilated, requiring mini-laparotomy for visualization. The enema, however, reduced the intussusception without any need for manual reduction. In the remaining 4 cases, minimal laparoscopic manipulation was required after the enema failed to completely reduce the intussusceptum, but enema was used to confirm reduction. No child required bowel resection. CONCLUSIONS: In cases of failed reduction by contrast enema, we have demonstrated LAHRI to be a successful treatment modality. The technique has the advantage of little to no bowel manipulation and has evolved into one performed via a single umbilical port.

Autistic traits modulate frontostriatal connectivity during processing of rewarding faces.

Deficits in facial mimicry have been widely reported in autism. Some studies have suggested that these deficits are restricted to spontaneous mimicry and do not extend to volitional mimicry. We bridge these apparently inconsistent observations by testing the impact of reward value on neural indices of mimicry and how autistic traits modulate this impact. Neutral faces were conditioned with high and low reward. Subsequently, functional connectivity between the ventral striatum (VS) and inferior frontal gyrus (IFG) was measured while neurotypical adults (n = 30) watched happy expressions made by these conditioned faces. We found greater VS-IFG connectivity in response to high reward vs low reward happy faces. This difference was negatively proportional to autistic traits, suggesting that reduced spontaneous mimicry of social stimuli seen in autism, may be related to a failure in the modulation of the mirror system by the reward system rather than a circumscribed deficit in the mirror system.

How reward modulates mimicry: EMG evidence of greater facial mimicry of more rewarding happy faces.

Spontaneous mimicry is a marker of empathy. Conditions characterized by reduced spontaneous mimicry (e.g., autism) also display deficits in sensitivity to social rewards. We tested if spontaneous mimicry of socially rewarding stimuli (happy faces) depends on the reward value of stimuli in 32 typical participants. An evaluative conditioning paradigm was used to associate different reward values with neutral target faces. Subsequently, electromyographic activity over the Zygomaticus Major was measured whilst participants watched video clips of the faces making happy expressions. Higher Zygomaticus Major activity was found in response to happy faces conditioned with high reward versus low reward. Moreover, autistic traits in the general population modulated the extent of spontaneous mimicry of happy faces. This suggests a link between reward and spontaneous mimicry and provides a possible underlying mechanism for the reduced response to social rewards seen in autism.

Continuous local delivery of interferon-ß stabilizes tumor vasculature in an orthotopic glioblastoma xenograft resection model.

BACKGROUND: High-grade glioblastomas have immature, leaky tumor blood vessels that impede the efficacy of adjuvant therapy. We assessed the ability of human interferon (hIFN)-ß delivered locally via gene transfer to effect vascular stabilization in an orthotopic model of glioblastoma xenograft resection. METHODS: Xenografts were established by injecting 3 grade IV glioblastoma cell lines (GBM6-luc, MT330-luc, and SJG2-luc) into the cerebral cortex of nude rats. Tumors underwent subtotal resection, and then had gel foam containing an adeno-associated virus vector encoding either hIFN-ß or green fluorescence protein (control) placed in the resection cavity. The primary endpoint was stabilization of tumor vasculature, as evidenced by CD34, α-SMA, and CA IX staining. Overall survival was a secondary endpoint. RESULTS: hIFN-ß treatment altered the tumor vasculature of GBM6-luc and SJG2-luc xenografts, decreasing the density of endothelial cells, stabilizing vessels with pericytes, and decreasing tumor hypoxia. The mean survival for rats with these neoplasms was not improved, however. In rats with MT330-luc xenografts, hIFN-ß resulted in tumor regression with a 6-month survival of 55% (INF-ß group) and 9% (control group). CONCLUSION: The use of AAV hIFN-ß in our orthotopic model of glioblastoma resection stabilized tumor vasculature and improved survival in rats with MT330 xenografts.

Targeting multiple angiogenic pathways for the treatment of neuroblastoma.

PURPOSE: Resistance to angiogenesis inhibition can occur through the upregulation of alternative mediators of neovascularization. We used a combination of angiogenesis inhibitors with different mechanisms of action, interferon-beta (IFN-beta) and rapamycin, to target multiple angiogenic pathways to treat neuroblastoma xenografts. METHODS: Subcutaneous and retroperitoneal neuroblastoma xenografts (NB-1691 and SK-N-AS) were used. Continuous delivery of IFN-beta was achieved with adeno-associated virus vector-mediated, liver-targeted gene transfer. Rapamycin was delivered intraperitoneally (5 mg/kg per day). After 2 weeks of treatment, tumor size was measured, and tumor vasculature was evaluated with intravital microscopy and immunohistochemistry. RESULTS: Rapamycin and IFN-beta, alone and in combination, had little effect on tumor cell viability in vitro. In vivo, combination therapy led to fewer intratumoral vessels (69% of control), and the remaining vessels had an altered phenotype, being covered with significantly more pericytes (13x control). Final tumor size was significantly less than controls in all tumor models, with combination therapy having a greater antitumor effect than either monotherapy. CONCLUSION: The combination of IFN-beta and rapamycin altered the vasculature of neuroblastoma xenografts and resulted in significant tumor inhibition. The use of combinations of antiangiogenic agents should be further evaluated for the treatment of neuroblastoma and other solid tumors.

Protein interactions and subcellular localization in S-RNase-based self-incompatibility.

The recent identification of several proteins playing key roles in S-RNase-based gametophytic self-incompatibility has led both to a greater understanding of the molecular biology of this response, as well as to questions regarding the precise mechanism by which compatible pollen tubes are recognized and accepted. A proposed variant SCF(SLF) (where SCF is SSK1/cullin/F-box and SLF is S-locus F-box) ubiquitin ligase complex is thought to play a central role in recognizing and inhibiting non-self S-RNases, but the exact role of ubiquitination remains unclear. How the possible sequestration of non-self S-RNases in a pollen vacuolar compartment can be reconciled with the need for protein interaction between S-RNase and the SCF(SLF) complex needs to be determined. Current work to answer these questions focuses on more precisely defining quantitative protein interactions and subcellular localization of proteins involved in S-RNase-based gametophytic self-incompatibility.

IFN-beta restricts tumor growth and sensitizes alveolar rhabdomyosarcoma to ionizing radiation.

Ionizing radiation is an important component of multimodal therapy for alveolar rhabdomyosarcoma (ARMS). We sought to evaluate the ability of IFN-beta to enhance the activity of ionizing radiation. Rh-30 and Rh-41 ARMS cells were treated with IFN-beta and ionizing radiation to assess synergistic effects in vitro and as orthotopic xenografts in CB17 severe combined immunodeficient mice. In addition to effects on tumor cell proliferation and xenograft growth, changes in the tumor microenvironment including interstitial fluid pressure, perfusion, oxygenation, and cellular histology were assessed. A nonlinear regression model and isobologram analysis indicated that IFN-beta and ionizing radiation affected antitumor synergy in vitro in the Rh-30 cell line; the activity was additive in the Rh-41 cell line. In vivo continuous delivery of IFN-beta affected normalization of the dysfunctional tumor vasculature of both Rh-30 and Rh-41 ARMS xenografts, decreasing tumor interstitial fluid pressure, increasing tumor perfusion (as assessed by contrast-enhanced ultrasonography), and increasing oxygenation. Tumors treated with both IFN-beta and radiation were smaller than control tumors and those treated with radiation or IFN-beta alone. Additionally, treatment with high-dose IFN-beta followed by radiation significantly reduced tumor size compared with radiation treatment followed by IFN-beta. The combination of IFN-beta and ionizing radiation showed synergy against ARMS by sensitizing tumor cells to the cytotoxic effects of ionizing radiation and by altering tumor vasculature, thereby improving oxygenation. Therefore, IFN-beta and ionizing radiation may be an effective combination for treatment of ARMS.

Improved intratumoral oxygenation through vascular normalization increases glioma sensitivity to ionizing radiation.

PURPOSE: Ionizing radiation, an important component of glioma therapy, is critically dependent on tumor oxygenation. However, gliomas are notable for areas of necrosis and hypoxia, which foster radioresistance. We hypothesized that pharmacologic manipulation of the typically dysfunctional tumor vasculature would improve intratumoral oxygenation and, thus, the antiglioma efficacy of ionizing radiation. METHODS AND MATERIALS: Orthotopic U87 xenografts were treated with either continuous interferon-beta (IFN-beta) or bevacizumab, alone, or combined with cranial irradiation (RT). Tumor growth was assessed by quantitative bioluminescence imaging; the tumor vasculature using immunohistochemical staining, and tumor oxygenation using hypoxyprobe staining. RESULTS: Both IFN-beta and bevaziumab profoundly affected the tumor vasculature, albeit with different cellular phenotypes. IFN-beta caused a doubling in the percentage of area of perivascular cell staining, and bevacizumab caused a rapid decrease in the percentage of area of endothelial cell staining. However, both agents increased intratumoral oxygenation, although with bevacizumab, the effect was transient, being lost by 5 days. Administration of IFN-beta or bevacizumab before RT was significantly more effective than any of the three modalities as monotherapy or when RT was administered concomitantly with IFN-beta or bevacizumab or 5 days after bevacizumab. CONCLUSION: Bevacizumab and continuous delivery of IFN-beta each induced significant changes in glioma vascular physiology, improving intratumoral oxygenation and enhancing the antitumor activity of ionizing radiation. Additional investigation into the use and timing of these and other agents that modify the vascular phenotype, combined with RT, is warranted to optimize cytotoxic activity.

The Skp1-like protein SSK1 is required for cross-pollen compatibility in S-RNase-based self-incompatibility.

The self-incompatibility (SI) response occurs widely in flowering plants as a means of preventing self-fertilization. In these self/non-self discrimination systems, plant pistils reject self or genetically related pollen. In the Solanaceae, Plantaginaceae and Rosaceae, pistil-secreted S-RNases enter the pollen tube and function as cytotoxins to specifically arrest self-pollen tube growth. Recent studies have revealed that the S-locus F-box (SLF) protein controls the pollen expression of SI in these families. However, the precise role of SLF remains largely unknown. Here we report that PhSSK1 (Petunia hybrida SLF-interacting Skp1-like1), an equivalent of AhSSK1 of Antirrhinum hispanicum, is expressed specifically in pollen and acts as an adaptor in an SCF(Skp1-Cullin1-F-box)(SLF) complex, indicating that this pollen-specific SSK1-SLF interaction occurs in both Petunia and Antirrhinum, two species from the Solanaceae and Plantaginaceae, respectively. Substantial reduction of PhSSK1 in pollen reduced cross-pollen compatibility (CPC) in the S-RNase-based SI response, suggesting that the pollen S determinant contributes to inhibiting rather than protecting the S-RNase activity, at least in solanaceous plants. Furthermore, our results provide an example that a specific Skp1-like protein other than the known conserved ones can be recruited into a canonical SCF complex as an adaptor.

Neural progenitor cell-mediated delivery of osteoprotegerin limits disease progression in a preclinical model of neuroblastoma bone metastasis.

PURPOSE: Osteoprotegerin (OPG) inhibits osteoclast activation and reduces osteolysis in bone tumors. We hypothesized that tumor-tropic neural progenitor cells (NPCs) engineered to express OPG would reduce neuroblastoma disease burden in the bone. METHODS: Stable expression of green fluorescent protein (NPC-GFP) and OPG (NPC-OPG) was established in human NPCs by lentivirus-mediated transduction. Bone disease was established by intrafemoral injection of luciferase-expressing human neuroblastoma (CHLA-255) cells into 20 SCID mice. Three weeks later, mice began receiving intravenous injection of 2 x 10(6) NPC-OPG or NPC-GFP (control) every 10 days x 3 doses. Disease was monitored with quantitative bioluminescence imaging and x-ray images, which were evaluated on a scale of 0 to 4. These studies were approved by the Institutional Animal Care and Use Committee. RESULTS: Osteoprotegerin treatment in vitro produced no direct toxicity to tumor cells. Coculture of tumor cells with bone marrow significantly increased activation of bone marrow-derived osteoclasts as assessed by tartrate-resistant acid phosphatase staining (156 +/- 10.8 osteoclasts per well) compared to bone marrow culture alone (91.67 +/- 4.7, P = .005). This increase was abrogated by adding OPG-containing media (68.3 +/- 2.8, P = .001). NPC-OPG slowed tumor progression (108-fold increase from pretreatment) compared to mice treated with NPC-GFP (538-fold), as judged by bioluminescence imaging. X-rays subjectively demonstrated less bone disease in NPC-OPG-treated mice (2.27 +/- 0.25) compared to NPC-GFP-treated mice (3.25 +/- 0.22, P = .04). CONCLUSIONS: Neural progenitor cell-mediated delivery of OPG slowed disease progression in a preclinical model of neuroblastoma bone metastasis. The decrease in bone disease was not from direct tumor cell toxicity but likely occurred indirectly through inhibition of osteoclast-directed bone resorption. Thus, targeted delivery of OPG by NPCs may be effective in the treatment of neuroblastoma bone metastasis.