Adequacy and Accuracy of Core Biopsy in Children: A Radiologic/Pathologic Correlation Study.

Core biopsy (CB) is increasingly popular for assessing solid lesions in children. To date, pediatric literature is limited regarding factors contributing to diagnostically inadequate or inaccurate CB. Therefore, we retrospectively examined radiologic/pathologic factors associated with adequacy/accuracy of CB in pediatric patients. A search of the surgical pathology database for CB between January 2007 and December 2014 yielded 134 CB from 99 patients. Age, sex, anatomic site of lesion, CB diagnosis, and final diagnosis were acquired from the electronic medical record. Image guidance modality, lesion size, and CB sampling device were obtained from radiology records. CB hematoxylin and eosin slides were reviewed for fragmentation, percentage of fibrosis, and percentage of necrosis. Overall, CB length was measured using cellSens software and a DP71 camera. Groups were compared using 2-sided homoscedastic Student's t tests; 87.3% (117/134) CB were diagnostic; final diagnosis was available for 105 cases, with a concordance rate of 80.0% (84/105). Image guidance modality, lesion site (extremity vs nonextremity), and CB needle gauge did not significantly differ between diagnostic versus nondiagnostic CB or concordant versus discordant CB. Diagnostic CB had less necrosis and fibrosis than did nondiagnostic CBs (6.8% vs 29.7%, P = .0002 and 10.3% vs 29.1%, P = .0006). Nondiagnostic and discordant CB were more likely to be from bony lesions than soft tissue ( P = .01 and P = .0248). CB is valuable for diagnosing solid lesions in children, with good overall diagnostic rates regardless of lesion size, location, or imaging modality used for biopsy. Nondiagnostic and discordant CB were more often obtained from bony lesions; sampling via open biopsy may be more useful in that setting. Nondiagnostic and discordant CB have more necrosis and fibrosis, suggesting that on-site evaluation of CB tissue viability-for example, by touch imprint or fine needle aspiration-may be useful in further enhancing CB utility.

Mimickers of Infantile Hemangiomas.

Infantile hemangiomas (IHs) are the most common tumors of infancy and usually follow a typical course of growth and involution. We report four soft tissue tumors that were referred to the pediatric dermatology clinic as IHs and the process by which they were diagnosed and treated. Clinicians should be aware of presentations of these uncommon, but serious soft tissue tumors. Many of these mimickers have a vastly different clinical prognosis, and early intervention to limit sequelae is crucial. Biopsy of atypical lesions should be considered early in the diagnostic process since they have varied prognosis and treatment strategies.

Pediatric Gastrojejunostomy Tube Replacement: Effects of Communication on the Need for After-Hours Procedures.

OBJECTIVES: The aim of the study was to determine whether embedding into the radiology report a patient-specific plan in the event of gastrojejunostomy (GJ) tube dysfunction reduces the need for after-hours utilization of pediatric interventional radiology resources for the replacement of GJ tubes. MATERIALS AND METHODS: This is a Health Insurance Portability and Accountability Act compliant, institutional review board-approved retrospective repeated cross-sectional study of patients requiring after-hours (5 PM-7 AM) or weekend (Saturday and Sunday) GJ tube replacement at a dedicated children's hospital, before and after the inclusion of a patient-specific plan in the radiology report as part of the electronic medical record. RESULTS: During a 6-month period before the inclusion of a patient-specific plan, there were 242 total GJ tube changes performed by the pediatric interventional radiology service under image guidance. Twenty-six (10.7%) of these procedures were performed outside of standard operating hours at the request of the emergency department (ED) (6/26), inpatient service (8/26), or patient/caregiver (12/26). Of the 8 inpatients, 3 were admitted from the ED for the sole purpose of tube replacement. Data were again collected for 6 months following inclusion of a patient-specific plan during the same seasonal period of the following year. During this period, 240 total image-guided changes were performed. Fifteen (6.2%) were performed outside of standard operating hours at the request of the ED (2/15), inpatient service (4/15), or patient/caregiver (9/15). No patients were admitted for GJ tube replacement procedures following implementation of the enhanced reporting policy. These data indicate a trend toward reduced after-hours resource utilization for GJ tube replacement requests by the ED (23.1%-13.3%), inpatient service (30.8%-26.7%), and all patients (14.7%-11%). Fewer after-hours GJ tube changes reduced cost by proportionately reducing hourly compensation for interventional radiology nurses and technicians. CONCLUSIONS: Our single-center data suggest that the inclusion of patient-specific recommendations at the end of each radiology GJ tube procedure note, generated in collaboration with the feeding service or primary medical provider, reduces off-hour resource utilization in patients who could otherwise have their tubes replaced during standard operating hours with image guidance. Avoidance of tube-related admissions is likely the greatest source of cost savings, followed by lower radiology technical support costs. Cost savings related to improved ED workflow and reduced patient/family anxiety are difficult to quantify, but likely significant. Future studies should be designed to quantify these savings and to assess the effect of this intervention on patient/caregiver satisfaction.

Agenesis of the venous duct: two cases of extrahepatic drainage of the umbilical vein and extrahepatic portosystemic shunt with a review of the literature.

Agenesis of the venous duct is a rare congenital anomaly resulting in abnormal drainage of the umbilical vein into the foetal venous circulation. The clinical presentation and prognosis is variable, and may depend on the specific drainage pathways of the umbilical vein. We present two foetuses with agenesis of the venous duct, both associated with a postnatal portosystemic shunt, but with markedly different postnatal clinical courses. We also review all previously reported cases to better characterise this foetal disorder and the prognosis.

Ultrasound-guided tunneled lower extremity peripherally inserted central catheter placement in infants.

Tunneled lower extremity peripherally inserted central catheters (PICCs) are placed in infants under combined ultrasound and fluoroscopic guidance in the interventional radiology suite. In infants requiring a bedside procedure, image guidance is limited, often using portable radiographs during the procedure. This report demonstrates feasibility of placing tunneled lower extremity PICCs using ultrasound as the sole imaging modality for vascular access, intravascular length measurement, and final confirmation of catheter tip position in a case series of 15 critically ill infants. The technique negates the need for added imaging confirmation methods that use ionizing radiation and can be performed at the bedside.

HIDA, percutaneous transhepatic cholecysto-cholangiography and liver biopsy in infants with persistent jaundice: can a combination of PTCC and liver biopsy reduce unnecessary laparotomy?

BACKGROUND: Historically, HIDA is the initial diagnostic test in the evaluation of biliary atresia (BA). Non-excreting HIDA scans can yield false-positive results leading to negative laparotomy. OBJECTIVE: Cholestatic infants must be evaluated promptly to exclude biliary atresia (BA) and other treatable hepatic conditions. Intraoperative cholangiogram (IOC) is the gold standard for diagnosing BA, but requires surgical intervention. Percutaneous transhepatic cholecysto-cholangiography (PTCC) and liver biopsy are less invasive and have been described in small case series. We hypothesized that PTCC and liver biopsy effectively exclude BA, thus avoiding unnecessary IOC. MATERIALS AND METHODS: Retrospective review of cholestatic infants who underwent PTCC, biopsy or cholescintigraphy at a tertiary children's hospital from August 1998 to January 2009. Group differences were evaluated and the receiver operator curve and safety of PTCC determined. RESULTS: One-hundred twenty-eight cholestatic infants were reviewed. Forty-six (36%) underwent PTCC. Forty-one out of 46 (89%) had simultaneous PTCC and liver biopsy. PTCC was completed successfully in 19/23 (83%) children despite a small or absent GB on initial US. Negative laparotomy rate was 1/6 (17%) for simultaneous PTCC/liver biopsy. Complications occurred in 4/46 including bleeding (n=2), fever with elevated transaminases (n=1) and oxygen desaturations (n=1). CONCLUSION: PTCC, particularly when performed in combination with simultaneous liver biopsy, effectively excludes BA in cholestatic infants with acceptable morbidity. PTCC can frequently be performed when a contracted gallbladder is seen on initial US exam. Negative laparotomy rate is lowest when PTCC is coupled with simultaneous liver biopsy.

Utilizing immediate preoperative n-BCA in the resection of head and neck venous and lymphatic malformations.

PURPOSE/OBJECTIVE: To add to the current literature on single stage excision of head and neck vascular malformations with preoperative n-butyl cyanoacrylate (n-BCA) glue. Unlike previous studies, this series includes pediatric and adult patients, highlights a single stage partial excision of a complex venous malformation, and describes the first description of using glue prior to resection of a macrocystic lymphatic malformation. STUDY DESIGN: Case series with chart review. SETTING: Tertiary-care adult and pediatric hospital. SUBJECTS AND RESULTS: Four patients (3 males - 9, 13, 25 years, 1 female - 61 years) underwent same day excision of head and neck vascular malformations utilizing immediate preoperative n-BCA glue embolization performed by interventional radiology and otolaryngology, as described by Tieu et al. The indications for resection included bleeding (1/4), pain (3/4), cosmetic deformity (3/4), and discomfort with denture wear (1/4). Prior interventions included none (1/4), cautery and primary closure to control acute hemorrhage (1/4), and sclerotherapy (2/4). Treatments included complete embolization and resection of simple venous malformation (VM)s of the oral cavity/lip (2/4), partial embolization and resection of a complex hemifacial venous malformation (VM) (1/4), and complete embolization and resection of a lymphatic malformation (LM) (1/4). On average, 97 min of anesthesia time was added for the preoperative embolization procedure (range, 94-104 min). All patients had a successful embolization without need for coils. Operative time ranged from 28 to 44 min for the simple cases and was 6 h and 30 min for the complex case. There was minimal blood loss in all cases. There were no associated complications, lesion recurrences, or long-term deficits at an average follow-up of 5 months. The patient with the complex hemifacial VM demonstrated subtle lower facial weakness post-operatively, which completely resolved within two months. CONCLUSIONS: Treatment of head and neck vascular malformations with preoperative n-BCA glue and subsequent surgical excision is a viable method for both simple and complex lesions. The safety and efficacy of this technique has been demonstrated in the past in a limited number of studies. This study further supports the use of this technique to address patient concerns such as pain or discomfort and cosmetic deformity, even if the lesion is only partially resectable. In our series a lymphatic malformation refractory to sclerotherapy was treated with a similar technique of glue and resection, following aspiration of the mucoid LM fluid. Our series emphasizes that pediatric vascular malformations carry functional and cosmetic deficits into adulthood that can and should be addressed in this patient population. Therefore, same-day embolization and resection should be coordinated when possible, in order to optimize patient safety and convenience.

Two Plasmodium falciparum ribonucleotide reductase small subunits, PfR2 and PfR4, interact with each other and are components of the in vivo enzyme complex.

Ribonucleotide reductase (RNR) is a tetrameric enzyme, composed of two large (R1) and two small (R2) subunits, which regulates the nucleotide balance in cells by controlling the rate-limiting step for deoxyribonucleotide synthesis. We have identified a second copy of the small subunit gene, termed PfR4, encoding a 324 amino acid residue polypeptide that shares only 25% identity with the previously identified PfR2 small subunit of Plasmodium falciparum. PfR4 expression is cell-cycle-regulated, and the profile of transcript and protein expression corresponds to that of PfR2. A 1.3 kb PfR4 5'-flanking fragment contained a functional promoter activity. We have detected interaction between PfR2 and PfR4 by co-immunoprecipitation experiments. Indirect immunofluorescence analysis showed distinct localization of two small RNR subunits with some colocalization. The association of PfR1 large subunit with PfR4 was detected by GST pull-down assay. This interaction is reduced significantly when using a PfR4 truncated at the COOH terminus, suggesting the involvement of COOH-terminal residues in PfR4-PfR1 interaction. All three RNR subunits co-eluted on a Superose 12 size-exclusion column corresponding to fractions with a molecular mass of around 250 kDa. This suggests the existence of all three RNR subunits in Plasmodium in a native complex of alpha2betabeta' configuration.

Functional level assessment of individuals with transtibial limb loss: Evaluation in the clinical setting versus objective community ambulatory activity.

The functional level (K level) of prosthetic users is used to choose appropriate prosthetic components, but ratings may highly subjective. A more objective and robust method to determine K level may be appealing. The aim of this study was to determine the relationship between K level determined in the clinic to K level based on real world ambulatory activity data collected by StepWatch. Twelve individuals with transtibial limb loss gave informed consent to participate. K level assessments performed in the clinic by a single treating prosthetist were compared with a calculated estimate based on seven days of real world ambulatory activity patterns using linear regression. There was good agreement between the two methods of determining K level with R 2 = 0.775 (p < 0.001). The calculated estimate of K level based on actual ambulatory activity in real world settings appears to be similar to the treating prosthetist's assessment of K level based on gait observation and patient responses in the clinic. Clinic-based ambulatory capacity in transtibial prosthetic users appears to correlate with real world ambulatory behavior in this small cohort. Determining functional level based on real world ambulatory activity may supplement clinic-based tests of functional capacity.

Biomechanical characteristics, patient preference and activity level with different prosthetic feet: a randomized double blind trial with laboratory and community testing.

Providing appropriate prosthetic feet to those with limb loss is a complex and subjective process influenced by professional judgment and payer guidelines. This study used a small load cell (Europa™) at the base of the socket to measure the sagittal moments during walking with three objective categories of prosthetic feet in eleven individuals with transtibial limb loss with MFCL K2, K3 and K4 functional levels. Forefoot stiffness and hysteresis characteristics defined the three foot categories: Stiff, Intermediate, and Compliant. Prosthetic feet were randomly assigned and blinded from participants and investigators. After laboratory testing, participants completed one week community wear tests followed by a modified prosthetics evaluation questionnaire to determine if a specific category of prosthetic feet was preferred. The Compliant category of prosthetic feet was preferred by the participants (P=0.025) over the Stiff and Intermediate prosthetic feet, and the Compliant and Intermediate feet had 15% lower maximum sagittal moments during walking in the laboratory (P=0.0011) compared to the Stiff feet. The activity level of the participants did not change significantly with any of the wear tests in the community, suggesting that each foot was evaluated over a similar number of steps, but did not inherently increase activity. This is the first randomized double blind study in which prosthetic users have expressed a preference for a specific biomechanical characteristic of prosthetic feet: those with lower peak sagittal moments were preferred, and specifically preferred on slopes, stairs, uneven terrain, and during turns and maneuvering during real world use.

The value of interventional radiology in re-establishment of lost access to catheterizable channels to the bladder and bowel.

OBJECTIVE: The efficacy of interventional radiology (IR) procedures in regaining lost access to continent catheterizable channels in pediatric urology patients is uninvestigated. This paper assesses this efficacy, as well as prevention of surgical revision of these channels as a result of IR intervention. METHODS: A retrospective chart analysis was performed over 8 years for children presenting with lost access to the bladder or bowel that could not be regained by a pediatric urologist. Rates of successful re-establishment of access in IR and the need for future surgical revision were calculated. RESULTS: Twenty pediatric patients underwent 32 attempts to re-establish lost access in IR. IR was successful in 78.1% (25/32) of episodes for 15/20 patients. No intervention required general anesthesia. Thirty percent (6/20) were able to avoid surgical revision. Another 45% (9/20) had access re-established in IR but later had surgery related to their channel (endoscopic, percutaneous, or open). Only three patients required open revision. The five patients in whom IR access failed, did require surgery. CONCLUSION: Image-guided re-establishment of access to continent catheterizable channels in children is efficacious. It can diffuse an emergency situation and delay or obviate the need for surgical correction. Additionally, a general anesthetic is not necessary.

Conformational instability of the cholera toxin A1 polypeptide.

Cholera toxin (CT) moves from the cell surface to the endoplasmic reticulum (ER) by vesicular transport. In the ER, the catalytic CTA1 subunit dissociates from the holotoxin and enters the cytosol by exploiting the quality control system of ER-associated degradation (ERAD). It is hypothesized that CTA1 triggers its ERAD-mediated translocation into the cytosol by masquerading as a misfolded protein, but the process by which CTA1 activates the ERAD system remains unknown. Here, we directly assess the thermal stability of the isolated CTA1 polypeptide by biophysical and biochemical methods and correlate its temperature-dependent conformational state with susceptibility to degradation by the 20S proteasome. Measurements with circular dichroism and fluorescence spectroscopy demonstrated that CTA1 is a thermally unstable protein with a disordered tertiary structure and a disturbed secondary structure at 37 degrees C. A protease sensitivity assay likewise detected the temperature-induced loss of native CTA1 structure. This protease-sensitive conformation was not apparent when CTA1 remained covalently associated with the CTA2 subunit. Thermal instability in the dissociated CTA1 polypeptide could thus allow it to appear as a misfolded protein for ERAD-mediated export to the cytosol. In vitro, the disturbed conformation of CTA1 at 37 degrees C rendered it susceptible to ubiquitin-independent degradation by the core 20S proteasome. In vivo, CTA1 was also susceptible to degradation by a ubiquitin-independent proteasomal mechanism. ADP-ribosylation factor 6, a cytosolic eukaryotic protein that enhances the enzymatic activity of CTA1, stabilized the heat-labile conformation of CTA1 and protected it from in vitro degradation by the 20S proteasome. Thermal instability in the reduced CTA1 polypeptide has not been reported before, yet both the translocation and degradation of CTA1 may depend upon this physical property.

The pertussis toxin S1 subunit is a thermally unstable protein susceptible to degradation by the 20S proteasome.

Pertussis toxin (PT) is an AB-type protein toxin that consists of a catalytic A subunit (PT S1) and an oligomeric, cell-binding B subunit. It belongs to a subset of AB toxins that move from the cell surface to the endoplasmic reticulum (ER) before the A chain passes into the cytosol. Toxin translocation is thought to involve A chain unfolding in the ER and the quality control mechanism of ER-associated degradation (ERAD). The absence of lysine residues in PT S1 may allow the translocated toxin to avoid ubiquitin-dependent degradation by the 26S proteasome, which is the usual fate of exported ERAD substrates. As the conformation of PT S1 appears to play an important role in toxin translocation, we used biophysical and biochemical methods to examine the structural properties of PT S1. Our in vitro studies found that the isolated PT S1 subunit is a thermally unstable protein that can be degraded in a ubiquitin-independent fashion by the core 20S proteasome. The thermal denaturation of PT S1 was inhibited by its interaction with NAD, a donor molecule used by PT S1 for the ADP ribosylation of target G proteins. These observations support a model of intoxication in which toxin translocation, degradation, and activity are all influenced by the heat-labile nature of the isolated toxin A chain.

Structural and functional effects of tryptophans inserted into the membrane-binding and substrate-binding sites of human group IIA phospholipase A2.

Phospholipase A(2) (PLA(2)) enzymes become activated by binding to biological membranes and hydrolyze phospholipids to free fatty acids and lyso-phospholipids, the precursors of inflammatory mediators. To understand the functional significance of amino acid residues at key positions, we have studied the effects of the substitution of Val(3) (membrane binding surface) and Phe(5) (substrate binding pocket) of human group IIA PLA(2) by tryptophan on the structure and function of the enzyme. Despite the close proximity of the sites of mutations, the V3W mutation results in substantial enhancement of the enzyme activity, whereas the F5W mutant demonstrates significantly suppressed activity. A structural analysis of all three proteins free in buffer and bound to membranes indicates that large differences in activities result from distinct conformational changes in PLA(2)s upon membrane binding. Although PLA(2) and the V3W mutant demonstrate a decrease in helical content and an increase in helix flexibility, the F5W mutant experiences partial distortion of the alpha-helical structure presumably resulting from the tendency of Trp(5) to insert into the membrane. Furthermore, whereas the PLA(2) and the V3W mutant bind to the membrane at similar and apparently productive-mode orientation, the F5W mutant binds to membranes with a distinctly different orientation. It is suggested that both the stimulatory effect of the V3W mutation and the inhibitory effect of the F5W mutation result from the high affinity of Trp for the membrane-water interface. Although Trp(3) at the membrane binding face of PLA(2) facilitates the proper membrane binding of the enzyme, Trp(5) in the internal substrate binding site causes partial unwinding of the N-terminal helix in order to interact with the membrane.

Modulation of human 5-lipoxygenase activity by membrane lipids.

Mammalian 5-lipoxygenase (5-LO) catalyzes the conversion of arachidonic acid (AA) to leukotrienes, potent inflammatory mediators. 5-LO is activated by a Ca(2+)-mediated translocation to membranes, and demonstrates the characteristic features of interfacially activated enzymes, yet the mechanism of membrane binding of 5-LO is not well understood. In an attempt to understand the mechanism of lipid-mediated activation of 5-LO, we have studied the effects of a large set of lipids on human recombinant 5-LO activity, as well as mutual structural effects of 5-LO and membranes. In the presence of 0.35 mM phosphatidylcholine (PC) and 0.2 mM Ca(2+), there was substrate inhibition at >100 microM AA. Data analysis at low AA concentrations yielded the following: K(m) approximately 103 microM and k(cat) approximately 56 s(-1). 5-LO activity was supported by PC more than by any other lipid tested except for a cationic lipid, which was more stimulatory than PC. Binding of 5-LO to zwitterionic and acidic membranes was relatively weak; the extent of binding increased 4-8 times in the presence of Ca(2+), whereas binding to cationic membranes was stronger and essentially Ca(2+)-independent. Polarized attenuated total reflection infrared experiments implied that 5-LO binds to membranes at a defined orientation with the symmetry axis of the putative N-terminal beta-barrel tilted approximately 45 degrees from the membrane normal. Furthermore, membrane binding of 5-LO resulted in dehydration of the membrane surface and was paralleled with stabilization of the structures of both 5-LO and the membrane. Our results provide insight into the understanding of the effects of membrane surface properties on 5-LO-membrane interactions and the interfacial activation of 5-LO.