In-utero radiofrequency ablation in fetal piglets: Lessons learned.

INTRODUCTION: Radiofrequency ablation (RFA) is increasingly utilized in minimally invasive fetal intervention. However, the response of different fetal tissues to RFA is poorly characterized. We sought to determine the extent of RFA damage in a fetal environment. METHODS: 90Day gestation Yorkshire piglets (term 115days) were subjected to RFA of the chest and abdominal viscera under various temperatures and wattages. The extent of tissue damage was determined by NADPH diaphorase histochemistry. RESULTS: Tyne temperature was widely variable and displayed varying responses between lung and liver tissue. Tyne exposure to amniotic fluid resulted in an increase in amniotic fluid temperature. Collateral damage, even across the diaphragm, was readily seen, and ultrasonography did not always reflect this injury. CONCLUSIONS: Utilization of extracorporeal tynes heats fluid at a greater rate than solid tissue and reliance on temperature sensitive probes may result in overheating. The extent of injury may extend beyond damage observed by ultrasound examination and varies for different tissues. Additional studies on the use of devices that regulate tyne temperature are needed to define optimal conditions and better define the extent of adjacent tissue injury.

Acute Operative Management of Humeral Shaft Fractures: Analysis of the National Trauma Data Bank.

Advances in surgical techniques have increased the role of early surgical intervention for isolated diaphyseal humerus fractures. The goal of this study was to investigate the following: (1) the current trend of operative treatment; (2) factors that affect surgical treatment; and (3) the effect of surgical fixation on length of stay, complication rates, and hospital disposition. The National Trauma Data Bank from 2004 to 2006 was analyzed. All patients with multiple injuries that included closed humeral shaft fractures and all patients with isolated humeral shaft fractures were included. Of 2312 total closed humeral shaft fractures, 1662 had a documented procedure code. A total of 47% of patients underwent surgical treatment. Surgically treated patients were on average 3.5 years older than those treated nonoperatively (P=.007). A total of 49% of white patients underwent early surgery vs 39% of nonwhite patients (P<.001). The operative group had a mean Injury Severity Score of 8.33 vs 9.0 in the nonoperative group (P=.04). Treatment at a Level I trauma center decreased the likelihood of surgery compared with treatment at a non-Level I trauma center (45% vs 57%, P<.001). Mean length of stay was 4.6 days for operative treatment vs 3.9 days for nonoperative treatment (P=.02). Of patients who underwent surgery, 78% were discharged to home compared with 69% of those managed nonoperatively (P<.001). Acute operative management of humeral shaft fractures correlated with a lower Injury Severity Score, a decreased length of stay, and less rehabilitation placement. Furthermore, older patients, white patients, and patients treated at a non-Level I trauma center were more likely to undergo acute surgical management. The reasons for these disparities are unclear and warrant further investigation.

Wound healing characteristics of ICAM-1 null mice devoid of all isoforms of ICAM-1.

BACKGROUND: Intercellular adhesion molecule-1 (ICAM-1) permits leukocyte-endothelial adhesion and transmigration during inflammation. Membrane-bound ICAM-1 knockout mice have been used to understand this molecule's role in wound-healing, but expressed spliced isoforms of ICAM-1 that may have impacted results. We aimed to characterize wound-healing in an ICAM-1 null model devoid of all ICAM-1 isoforms. METHODS: Full-thickness 8-mm wounds were created on C57/BL6 wild-type (n = 24) and ICAM-1 null (n = 24) mice. Wound area was calculated using daily photographs. Histologic samples were harvested on postoperative Days 1, 3, 7, and 14. Wound margins were evaluated for mRNA expression of 13 inflammatory cytokines. A separate group of wild-type and ICAM-1 null mice (n = 24) received full-thickness incisions with tensiometry measured at Day 14. Separately, complete blood counts were measured in unwounded wild-type (n = 4) and ICAM-1 null mice (n = 4). RESULTS: Wound-closure was significantly delayed in ICAM-1 null mice through Day 7 by gross and histologic measurement. mRNA expression of VEGF-A was increased in ICAM-1 null mice on Day 3, although no increase in VEGF-A was observed in the wound bed by immunohistochemistry. ICAM-1 null wounds demonstrated higher stiffness by tensiometry on Day 14 compared to the wild-type (1880 ± 926 kPa versus 478 ± 117 kPa; P < 0.01), and had higher counts of white blood cells (10,009 versus 5720 cells/µL, P < 0.05), neutrophils (2130 versus 630 cells/µL, P < 0.01), and lymphocytes (7130 versus 4,740 cells/µL, P < 0.05). CONCLUSIONS: ICAM-1 null mice demonstrate delayed wound-healing and decreased wound elasticity compared to wild-type controls. This lag, however, was less than observed in earlier membrane-bound ICAM-1 knockouts, suggesting that other ICAM-1 isoforms may promote delayed wound-healing.

Near-infrared spectroscopy measurement of abdominal tissue oxygenation is a useful indicator of intestinal blood flow and necrotizing enterocolitis in premature piglets.

PURPOSE: A major objective of necrotizing enterocolitis (NEC) research is to devise a noninvasive method of early detection. We hypothesized that abdominal near-infrared spectroscopy (A-NIRS) readings will identify impending NEC in a large animal model. METHODS: Piglets were prematurely delivered and received parenteral nutrition followed by enteral feedings. Serial A-NIRS readings were obtained for 5 days, and animals were monitored for NEC. Separately, A-NIRS readings were obtained in healthy piglets to validate the correlation of A-NIRS with splanchnic oxygen delivery. RESULTS: Of 29 piglets, 3 developed NEC. Eleven piglets without NEC died prematurely. Fifteen piglets remained healthy, had normal histologic assessment of their intestines, and served as controls. Abdominal near-infrared spectroscopy readings within 12 hours of birth were significantly lower in animals that developed NEC compared with healthy littermates (4% vs 33%, P = .02). For all time-points measured, A-NIRS readings were significantly lower in the NEC group compared with controls (21% vs 55%, P < .001). Abdominal near-infrared spectroscopy readings correlated with both decreased pulse oximetry readings during apneic episodes (r = 0.96) and increased superior mesenteric artery flow in response to glucagon-like peptide 2 (r = 0.67). CONCLUSION: Abdominal near-infrared spectroscopy is capable of detecting alterations in intestinal oxygenation and perfusion in neonatal piglets and may allow early detection of neonates at risk for NEC.

Imaging accuracy and incidence of Wilms' and non-Wilms' renal tumors in children.

PURPOSE: The purpose of this study is to determine the actual incidence, age distribution, and preoperative imaging accuracy of non-Wilms' tumors (nWT) in children with renal masses. METHODS: Pathologic reports from all tumor nephrectomies or open renal biopsies performed at a single institution from September 1999 to June 2005 were analyzed. Patient demographics, pathologic findings, specific imaging study descriptors, and differential diagnoses were tabulated. Accuracy of imaging studies in identifying specific tumors was calculated. RESULTS: Ninety-two patients were identified. Sixty-eight had Wilms' tumor (WT) and 24 had an nWT. The nWT group included congenital mesoblastic nephroma (5), clear cell sarcoma (4), neuroblastoma (4), renal cell carcinoma (4), lymphoma (2), angiomyolipoma (2), teratoma (1), hemangioma (1), and renal epithelial tumor (1). When grouped by ages, the incidence of nWT was between 0% and 83%. Sensitivity, specificity, positive predictive value, and negative predictive value for computed tomography (CT) determining a diagnosis of WT were 0.92, 0.55, 0.84, and 0.73, respectively. The CT reports explicitly stated a potential diagnosis in 89% of cases, with a diagnostic accuracy of 82%. CONCLUSIONS: Non-Wilms' tumors may represent a significant proportion of renal tumors in children, especially in children aged less than 6 months or greater than 12 years. Preoperative imaging is of limited value in differentiating these tumors. These data have significant implications for parental counseling, surgical plan, and the choice of neoadjuvant chemotherapy and argue in favor of obtaining a tissue diagnosis before instituting therapy.

Granulocyte colony stimulating factor alters the phenotype of neuroblastoma cells: implications for disease-free survival of high-risk patients.

INTRODUCTION: Granulocyte colony stimulating factor (GCSF) is commonly used for the treatment of chemotherapy-induced neutropenia. Despite high-dose intensive chemotherapy for advanced-stage neuroblastoma, the survival rate remains poor. Granulocyte colony stimulating factor therapy is quite common in these children; thus, we questioned its effect on neuroblastoma cells. We hypothesized that exogenous GCSF stimulates the proliferation and invasive character of neuroblastoma cells. METHODS: Expression of a GCSF receptor in 5 different neuroblastoma cell lines was determined by polymerase chain reaction. In addition, we determined the effect of increasing doses of GCSF (0, 1 ng/mL, 10 ng/mL, 1 microg/mL, and 10 microg/mL) on DNA synthesis (BrdU assay), invasiveness (Matrigel invasion chambers), and cell proliferation. RESULTS: We tested 5 neuroblastoma cell lines; all expressed the GCSF receptor. Granulocyte colony stimulating factor treatment resulted in significantly increased proliferation of SK-N-SH, SK-N-AS, and SHSY-5Y cells. Likewise, increased invasiveness of SK-N-SH cells was observed with GCSF treatment. CONCLUSIONS: Our results indicate that neuroblastoma cell lines express the GCSF receptor and respond to exogenous GCSF by increased proliferation and invasiveness. These findings suggest that GCSF may stimulate the growth of neuroblastoma cells in patients undergoing high-dose chemotherapy with GCSF rescue and could have a significant impact on the ability to eradicate these tumors.

Fetal wound healing using a genetically modified murine model: the contribution of P-selectin.

PURPOSE: During early gestation, fetal wounds heal with paucity of inflammation and absent scar formation. P-selectin is an adhesion molecule that is important for leukocyte recruitment to injury sites. We used a murine fetal wound healing model to study the specific contribution of P-selectin to scarless wound repair. METHODS: Linear excisional wounds were created on the dorsa of E15.5 and E17.5 gestation fetuses in wild-type and P-selectin (-/-) mice (term = 19 days). Wounds were harvested at various time-points after wounding and analyzed using histology and immunohistochemistry. RESULTS: The E15.5 wounds in both wild-type and P-selectin (-/-) fetuses healed scarlessly and with minimal inflammation, whereas E17.5 wounds healed with fibrosis and inflammation. However, the scars of the P-selectin (-/-) wounds appeared slightly different than wild-type. There were significantly more inflammatory cells in E17.5 wild-type wounds 6 hours after injury (P < .001), but the difference was no longer significant by 24 hours. Finally, reepithelialization was slower in the E15.5 knockout wounds compared to their wild-type counterparts. CONCLUSIONS: Absence of P-selectin delays inflammatory cell recruitment and reepithelialization of fetal wounds; however, scar formation still occurs in late gestation wounds. The contribution of specific molecules to fetal wound healing can be elucidated using murine knockout or transgenic models.

Serum amyloid P inhibits dermal wound healing.

The repair of open wounds depends on granulation tissue formation and contraction, which is primarily mediated by myofibroblasts. A subset of myofibroblasts originates from bone-marrow-derived monocytes which differentiate into fibroblast-like cells called fibrocytes. Serum amyloid P (SAP) inhibits differentiation of monocytes into fibrocytes. Thus, we hypothesized that the addition of exogenous SAP would hinder the normal wound healing process. Excisional murine dorsal wounds were either injected with SAP (intradermal group) or the mice were treated with systemic SAP (intraperitoneal group) and compared with animals treated with vehicle. Grossly, SAP-treated wounds closed slower than respective controls in both groups. Histologically, the contraction rate was slower in SAP-treated wounds in both groups and the reepithelialization rate was slower in the intraperitoneal group. Furthermore, significantly less myofibroblasts expressing alpha-smooth muscle actin were noted in the intraperitoneal group wounds compared with controls. These data suggest that SAP delays normal murine dermal wound healing, probably due to increased inhibition of fibrocyte differentiation, and ultimately a decreased wound myofibroblast population. SAP may provide a potential therapeutic target to prevent or limit excessive fibrosis associated with keloid or hypertrophic scar formation. Furthermore, SAP removal from wound fluid could potentially accelerate the healing of chronic, nonhealing wounds.

Negative pressure therapy is effective to manage a variety of wounds in infants and children.

Negative pressure therapy (NPT) has been accepted as a valuable adjunct for wound closure in adults; however, reports on its effectiveness in young children and infants, including neonates, are limited. A retrospective chart review was conducted on children treated with NPT at a single institution between January 2003 and December 2005. Wound volumetric measurements were calculated at the start and end of therapy. Sixty-eight patients with 82 wounds were identified. The mean age was 8.5 years (range 7 days-18 years). Twenty patients (29%) were 2 years of age or younger, including eight neonates. Wound types included: pressure ulcers (n=13), extremity wounds (n=18), dehisced surgical wounds (n=19), open sternal wounds (n=10), wounds with fistulas (n=3), and complex abdominal wall defects (n=6). Low suction pressures (<100 mmHg) were generally used in children younger than 4 years of age. Following NPT, 93% of wounds decreased in volume. The average wound volume decrease was 80% (p<0.01, n=56). NPT can be effectively used to manage a variety of wounds in children and neonates. No major complications were identified in our retrospective review. Prospective studies are required to better refine the use of this technology in children.