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The affinity constant, also known as the equilibrium constant, binding constant, equilibrium association constant, or the reciprocal value, the equilibrium dissociation constant (K d ), can be considered as one of the most important characteristics for any antibody-antigen pair. Many methods based on different technologies have been proposed and used to determine this value. However, since a very large number of publications and commercial datasheets do not include this information, significant obstacles in performing such measurements seem to exist. In other cases where such data are reported, the results have often proved to be unreliable. This situation may indicate that most of the technologies available today require a high level of expertise and effort that does not seem to be available in many laboratories. In this paper, we present a simple approach based on standard immunoassay technology that is easy and quick to perform. It relies on the effect that the molar IC 50 approaches the K d value in the case of infinitely small concentrations of the reagent concentrations. A two-dimensional dilution of the reagents leads to an asymptotic convergence to K d . The approach has some similarity to the well-known checkerboard titration used for the optimization of immunoassays. A well-known antibody against the FLAG peptide, clone M2, was used as a model system and the results were compared with other methods. This approach could be used in any case where a competitive assay is available or can be developed. The determination of an affinity constant should belong to the crucial parameters in any quality control of antibody-related products and assays and should be mandatory in papers using immunochemical protocols.

The aim was to assess the results of primary anastomosis (PA) compared to enterostomy (ES) in infants with spontaneous intestinal perforation (SIP) and a weight below 1000 g. Between 2014 and 2016, enterostomy was routinely carried out on extremely low birth weight (ELBW) patients with SIP. From 2016 until 2019, all patients underwent anastomosis without stoma formation. We compared outcome and complications in both groups. Forty-two patients with a median gestational age of 24.3 weeks and a birth weight of 640 g with SIP were included. Thirty patients underwent PA; ES was performed in 12 patients. Overall in-hospital mortality was 11.9% (PA: 13.3%, ES: 8.3%). Reoperations due to complications became necessary in 10/30 patients with PA and 4/12 patients with ES. Length of stay was 110.5 days in the PA group and 124 days in the ES group. Median weight at discharge was higher in the PA group (PA: 2258 g, ES: 1880 g, p = .036).Conclusion: Primary anastomosis is a feasible treatment option for SIP in infants < 1000 g and may have a positive impact on weight gain and length of hospitalization. However, further studies on selection criteria for PA are necessary. What is Known: • Enterostomy (ES) and primary anastomosis (PA) are feasible treatment options in preterm infants with spontaneous intestinal perforation (SIP). • Stomal complications or failure to thrive due to poor food utilization can pose significant problems. What is New: • Primary anastomosis in case of SIP is equal to enterostomy in terms of mortality and revision rate; however, length of stay and weight gain can be presumably positively influenced. • Primary anastomosis is a valid treatment option even for patients weighing less than 1000 g.

Introduction:  Esophageal atresia (EA) is often accompanied by tracheobronchial malformations leading to stridor, recurrent bronchitis, and occasionally to life-threatening obstructive apnea after surgical repair. The aim of this study was to identify the presence of tracheomalacia in patients with EA and tracheoesophageal fistula (TEF) pre- and postoperatively and to find endoscopic correlates leading to clinical airway symptoms., Methods:  In a cohort of 362 patients with EA-TEF who underwent 595 tracheoscopies at the Children's Hospital of Cologne between January 1983 and December 2002, impaired tracheal lumen, localization of TEF, tracheal pulsations, and corresponding clinical symptoms were retrospectively analyzed., Results:  The incidence of tracheomalacia was higher in patients with EA and TEF (Gross B-D) compared with patients with EA alone (Gross A) and average tracheal collapse does not significantly change before and after surgical repair of the esophagus in all types. Patients with cyanosis while eating and obstructive apnea presented with an average tracheal collapse of 89%. The presence of respiratory symptoms such as cough, stridor, or bronchitis was not associated with a higher grade of tracheal collapse compared with patients without any airway symptoms (average tracheal collapse of 37% in symptomatic patients vs. 33% in nonsymptomatic patients)., Conclusion:  Tracheomalacia tends to be present independently of surgical procedure. Tracheomalacia should be measured by tracheoscopy (in % of tracheal collapse). Patients with a tracheal collapse of >80%, a ventral pulsation, and obstructive apnea or cyanosis in combination, are at risk for life-threatening situations and further surgical treatment should be considered., Competing Interests: None declared., (Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: Telomere maintenance is a hallmark of high-risk neuroblastoma; however, the contribution of telomerase and alternative lengthening of telomeres (ALT) to clinical phenotypes has remained unclear. We aimed to determine the clinical relevance of telomerase activation versus ALT as biomarkers in pretreatment neuroblastoma and to assess the potential value of telomerase as a therapeutic target., Materials and Methods: The genomic status of TERT and MYCN was assessed in 457 pretreatment neuroblastomas by fluorescence in situ hybridization. ALT was examined in 273 of 457 tumors by detection of ALT-associated promyelocytic leukemia nuclear bodies, and TERT expression was determined by microarrays in 223 of these. Cytotoxic effects of telomerase-interacting compounds were analyzed in neuroblastoma cell lines in vitro and in vivo., Results: We detected TERT rearrangements in 46 of 457 cases (10.1%), MYCN amplification in 93 of 457 cases (20.4%), and elevated TERT expression in tumors lacking TERT or MYCN alterations in 10 of 223 cases (4.5%). ALT activation was found in 49 of 273 cases (17.9%). All these alterations occurred almost mutually exclusively and were associated with unfavorable prognostic variables and adverse outcome. The presence of activated telomerase (ie, TERT rearrangements, MYCN amplification, or high TERT expression without these alterations) was associated with poorest overall survival and was an independent prognostic marker in multivariable analyses. We also found that the telomerase-interacting compound 6-thio-2'-deoxyguanosine effectively inhibited viability and proliferation of neuroblastoma cells bearing activated telomerase. Similarly, tumor growth was strongly impaired upon 6-thio-2'-deoxyguanosine treatment in telomerase-positive neuroblastoma xenografts in mice., Conclusion: Our data suggest telomerase activation and ALT define distinct neuroblastoma subgroups with adverse outcome and that telomerase may represent a promising therapeutic target in many high-risk neuroblastomas.

Aim: The creation of a primary anastomosis in newborns with oesophageal atresia and distal oesophageotracheal fistula (EA-DF) is technically challenging, especially in small children. The goal is to approximate the fragile oesophageal ends without suture disruption and to minimize the mobilisation of the lower segment. We describe an alternative anastomosis technique aiming at reducing the tension on the first sutures at the posterior wall., Indications: EA-DF was corrected in 13 newborns either by open (n = 11) or thoracoscopic (n = 2) surgery using this technique., Method: The anastomosis technique is based on creation of a dorsal flap of the upper oesophageal pouch and insertion in the spatulated lower oesophageal segment after the fistula has been separated. Subsequently, the first sutures of the posterior wall can be accomplished with reduced tension. Upon completion of the anastomosis, a diagonally shaped anastomotic plane results., Conclusion: The method is a helpful alternative to approximate the oesophageal stumps of newborns with EA and distal oesophagotracheal fistula. By this technique, the first stabilising sutures of the posterior wall can be accomplished with reduced tension. This results in reduced tensile stress on the individual sutures and simplifies the anastomisation in comparison to the conventional end-to-end anastomosis., Competing Interests: Die Autoren geben an, dass kein Interessenkonflikt besteht., (Georg Thieme Verlag KG Stuttgart · New York.)

Neuroblastoma is a pediatric tumor of the sympathetic nervous system. Its clinical course ranges from spontaneous tumor regression to fatal progression. To investigate the molecular features of the divergent tumor subtypes, we performed genome sequencing on 416 pretreatment neuroblastomas and assessed telomere maintenance mechanisms in 208 of these tumors. We found that patients whose tumors lacked telomere maintenance mechanisms had an excellent prognosis, whereas the prognosis of patients whose tumors harbored telomere maintenance mechanisms was substantially worse. Survival rates were lowest for neuroblastoma patients whose tumors harbored telomere maintenance mechanisms in combination with RAS and/or p53 pathway mutations. Spontaneous tumor regression occurred both in the presence and absence of these mutations in patients with telomere maintenance-negative tumors. On the basis of these data, we propose a mechanistic classification of neuroblastoma that may benefit the clinical management of patients., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Background:  The incidence of invasive aspergillosis (IA) in children with hematooncological malignancies is increasing as a result of intensive treatment, immunosuppression, and extended use of broad-spectrum antibiotics. Infection of the GI tract by Aspergillus spp. is a rare and fatal complication, which often requires surgical diagnostic and therapeutic exploration., Objective:  The aim of this study was to determine the characteristics of symptomatic intestinal aspergillosis, diagnosis, treatment, and outcome of pediatric patients with an underlying hemato-oncologic disease., Patients and Methods:  We analyzed 2,307 German patients with acute lymphoblastic leukemia (ALL) from age 1 to 17 years registered in the AIEOP-BFM ALL 2000 study from 2000 to 2006. All reported adverse events were assessed for symptoms of IA and retrospectively reviewed for any sign or proof of intestinal involvement of IA., Results:  In this cohort, IA was reported in 30 of 2,307 patients while intestinal involvement was documented in five patients. Four of these patients had intestinal symptoms and three patients underwent explorative laparotomy. Among clinical cases with IA, gastrointestinal manifestation of IA mostly occurred in adolescent patients (10-16 years). Symptoms varied from abdominal tenderness and pain to constipation. Intestinal aspergillosis was proven by microbiological and histopathological examination and fungal infection was observed macroscopically in the jejunal lumen during surgery. Despite the extended surgery and antifungal therapy, outcome of disseminated IA with intestinal involvement remains poor., Conclusion:  Surgeons should be aware of surgical complications of intestinal aspergillosis in children with hematooncological diseases requiring exploration and resection. IA is a rare event and still difficult to diagnose due to unspecific abdominal symptoms. Thus, biopsy sampling is of utmost importance to ensure diagnosis, and resection of necrotic or perforated tissue should be attempted early., Competing Interests: None., (Georg Thieme Verlag KG Stuttgart · New York.)

Background: Spinal cord stimulation (SCS) is an established treatment option for patients with refractory chronic pain conditions. While effects of SCS on dorsal horn neuronal circuitries are intensively studied, current knowledge on the impact of SCS on descending pain pathways is scarce and relies on preclinical data. We aimed to address this topic and hypothesized a significant effect of SCS on descending pain modulation. In light of current efforts to determine the sensitivity of "static" versus "dynamic" somatosensory parameters to characterize pathophysiological pain conditions, all SCS patients were carefully investigated using both classes of somatosensory outcome parameters., Methods: Descending pain pathways were investigated by using a "Cold Pressor Test." This test enables to evaluate the efficacy of conditioned pain modulation (CPM) at the individual level. CPM efficacy was assessed in eight neuropathic pain patients (age 55.5 ± 10.6) during the two conditions stimulator "ON" and "OFF." The impact of SCS on "static" and "dynamic" somatosensory parameters was explored by using a quantitative sensory testing (QST) battery., Results: CPM efficacy on pressure pain sensitivity was nearly absent during "OFF" (- 1.2 ± 5.6% facilitation), but increased significantly to 16.3 ± 3.4% inhibition during "ON" (p = 0.03). While most "static" nociceptive QST parameters, represented by mechanical/thermal pain thresholds, exhibited only small effects of SCS (p > 0.05), the wind-up ratio was strongly reduced to within the normal range during "ON" (p = 0.04; Cohen's d = 1.0). Dynamic mechanical allodynia was abolished in six of seven patients., Conclusions: Our study provides first human evidence for an impact of SCS on descending pain pathways in the dorsolateral funiculus and emphasizes the significance of "dynamic" pain measures like "CPM"-efficacy and "temporal summation" to evaluate SCS treatment effects. Future prospective studies may use these measures of nociceptive processing to predict SCS therapy response.

Background: Transumbilical laparoscopic-assisted appendectomy (TULAA) is fast and cost-effective since no endoloops, staplers or wound protection devices are used. We analyzed the effects of TULAA as first approach for perforated (PA) and non-perforated (NPA) appendicitis in children., Patients: We performed a retrospective analysis of 181 children for whom TULAA was the first approach for appendicitis between October 2010 and March 2016., Methods: Morbidity, additional laparoscopic instrument insertion (AI), conversions to open extraumbilical appendectomy (OC), and complications were evaluated., Results: TULAA was initiated in 181 (87.4%) children (113 boys: 68 girls). Median age was 10.3 years (3.3-13.9 years) and BMI 16.8 kg/m2 (12.4-30.8). Appendicitis was non-perforated in 157 (86.7%) and perforated in 24 (13.3%) patients. TULAA was finalized in 142 (78.5%) patients, AI were inserted in 20 (11%) and OC were performed in 19 (10.5%) patients. Duration of surgery did not exceed 20 min for 12.8%, and 30 min for 43.6% of patients with TULAA and NPA. The rate of wound infections did not differ between procedures (TULAA 3/142 (2.1%), AI 0 (0%), OC 1/19 (5.3%), P=1.000). Further postoperative course was uneventful in 179 (98.9%) patients., Conclusion: TULAA can be used as first approach for appendicitis in all children with a low rate of complications. Extracorporeal appendix stump closure can be safely achieved in the majority of children without using laparoscopic disposable devices., Competing Interests: The authors have no conflict of interest to disclose., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background/purpose: The impact of abdominal topography and surgical technique on resectability and local relapse pattern of relapsed abdominal high-risk neuroblastoma (R-HR-NB) is not clearly defined., Methods: A sample of thirty-nine patients with R-HR-NB enrolled in the German neuroblastoma trials between 2001 and 2010 was analyzed retrospectively using surgical and imaging reports. We evaluated resectability and local relapse pattern within 6 standardized abdominal regions, impact of extent of the first resective surgery on overall survival (OS), and of number of operations and a higher cumulative surgical assessment score (C-SAS) on OS after the first event., Results: In the left upper abdomen, rates for tumor persistence and relapse were 45.9% and 13.5% and in the left lower abdomen 27.7% and 8.3%, respectively. OS in months did not differ between complete and incomplete first resections (median (interquartile range): 35 (45.6) vs. 40 (65.4), P=.649). Better OS after the first event was associated with repeated as compared to single surgery (47.7 (64.7) vs. 4.3 (12.5), P=.000), and with higher as compared to lower C-SAS (47.7 (64.3) vs. 7.6 (14.7), P=.002)., Conclusions: OS after relapse/progression was not dependent on the extent of first resection. The number of operations was associated with better outcome after event., Type of Study: Treatment study., Level of Evidence: LEVEL III Retrospective comparative study., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Although several studies have been conducted on the role of surgery in localized neuroblastoma, the impact of surgical timing and extent of primary tumor resection on outcome in high-risk patients remains controversial., Methods: Patients from the German neuroblastoma trial NB97 with localized neuroblastoma INSS stage 1-3 age > 18 months were included for retrospective analysis. Imaging reports were reviewed by two independent physicians for Image Defined Risk Factors (IDRF). Operation notes and corresponding imaging reports were analyzed for surgical radicality. The extent of tumor resection was classified as complete resection (95-100%), gross total resection (90-95%), incomplete resection (50-90%), and biopsy (<50%) and correlated with local control rate and outcome. Patients were stratified according to the International Neuroblastoma Risk Group (INRG) staging system. Survival curves were estimated according to the method of Kaplan and Meier and compared by the log-rank test., Results: A total of 179 patients were included in this study. 77 patients underwent more than one primary tumor operation. After best surgery, 68.7% of patients achieved complete resection of the primary tumor, 16.8% gross total resection, 14.0% incomplete surgery, and 0.5% biopsy only. The cumulative complication rate was 20.3% and the surgery associated mortality rate was 1.1%. Image defined risk factors (IDRF) predicted the extent of resection. Patients with complete resection had a better local-progression-free survival (LPFS), event-free survival (EFS) and OS (overall survival) than the other groups. Subgroup analyses showed better EFS, LPFS and OS for patients with complete resection in INRG high-risk patients. Multivariable analyses revealed resection (complete vs. other), and MYCN (non-amplified vs. amplified) as independent prognostic factors for EFS, LPFS and OS., Conclusions: In patients with localized neuroblastoma age 18 months or older, especially in INRG high-risk patients harboring MYCN amplification, extended surgery of the primary tumor site improved local control rate and survival with an acceptable risk of complications.

A novel dimer nanostructure architecture featuring two symmetrically arranged crescents with opposing, nanometer-sized tips in close proximity is fabricated by colloidal lithography. This structure exhibits a strong and highly localized electrical near-field in the gap region between the tips. The close proximity of the tips in the nanocrescent dimers leads to a strong coupling process which generates new hybrid plasmon modes with different optical resonances. The optical properties of both single crescents and dimeric double crescent arrangements are investigated in detail, and correlations between resonance wavelengths and geometrical parameters are established. We apply plasmon hybridization theory to explain the spectral shifts between coupled and uncoupled crescent nanostructures based on simple geometric arguments for all polarization-dependent resonances. Computer simulations support the hybridization model and were further used to examine and compare the near-field enhancement of single and opposing double crescents. For close proximities of the two opposing crescents, a strong near-field with an enhancement factor of approximately 53 was detected. Compared to the near-field enhancement of approximately 20 for single crescents, the proximity of the second crescents further increases the near-field to more than seven times the initial value.

A series of linear and angular distyrylpyrazines and lateral donor groups has been prepared by aldol condensation between dimethylpyrazines and the appropriate aromatic aldehyde. The optical absorption and emission properties of these systems were studied in different solvents and media. The materials display a strong solvatochromism of the emission that is reflected by large red shifts of their fluorescence emission maxima on increasing the solvent polarity. This behaviour suggests a highly polar emitting state, which is characteristic of compounds that undergo an internal charge transfer upon excitation. Upon protonation, the UV-vis spectra are altered, and the fluorescence intensity of the neutral compound vanishes. These molecules can be used as colorimetric and luminescence polarity and pH sensors.

The title compound, C(26)H(30)N(4), was prepared by condensation of tetra-methyl-pyrazine and dimethyl-amino-benzaldehyde and crystallizes from chloro-form/methanol in two different forms. Block-shaped crystals belong to the monoclinic crystal system and plates to the triclinic system. The two crystal forms differ in the arrangement of the centrosymmetric mol-ecules, which have nearly identical geometries. In the monoclinic crystals reported here, planar mol-ecules [maximum deviation = 0.062 (2) Å], with a transoid arrangement of the (E)-styryl units and completely planarized dimethylamino groups [sum of the C-N bond angles = 359.9 (2)°], form layers connected via H-π-stacking. The dihedral angle between the central and pendant rings is 1.30 (8)°. The triclinic polymorph contains two half molecules, both completed by crystallographic inversion symmetry.

We apply colloidal lithography to construct stacked nanocrescent dimer structures with an exact vertical alignment and a separation distance of approximately 10 nm. Highly ordered, large arrays of these nanostructures are accessible using nonclose-packed colloidal monolayers as masks. Spatially separated nanocrescent dimers are obtained by application of spatially distributed colloids. The polarization dependent optical properties of the nanostructures are investigated in detail and compared to single crescents. The close proximity of the nanocrescents leads to a coupling process that gives rise to new optical resonances which can be described as linear superpositions of the individual crescents' plasmonic modes. We apply a plasmon hybridization model to explain the spectral differences of all polarization dependent resonances and use geometric arguments to explain the respective shifts of the resonances. Theoretical calculations are performed to support the hybridization model and extend it to higher order resonances not resolved experimentally.

The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) is involved in glucose homeostasis and synthetic PPARgamma ligands, the thiazolidinediones, a new class of antidiabetic agents that reduce insulin resistance and, as a secondary effect, reduce hepatic glucose output. PPARgamma is highly expressed in normal human pancreatic islet alpha-cells that produce glucagon. This peptide hormone is a functional antagonist of insulin stimulating hepatic glucose output. Therefore, the effect of PPARgamma and thiazolidinediones on glucagon gene transcription was investigated. After transient transfection of a glucagon-reporter fusion gene into a glucagon-producing pancreatic islet cell line, thiazolidinediones inhibited glucagon gene transcription when PPARgamma was coexpressed. They also reduced glucagon secretion and glucagon tissue levels in primary pancreatic islets. A 5'/3'-deletion and internal mutation analysis indicated that a pancreatic islet cell-specific enhancer sequence (PISCES) motif within the proximal glucagon promoter element G1 was required for PPARgamma responsiveness. This sequence motif binds the paired domain transcription factor Pax6. When the PISCES motif within G1 was mutated into a GAL4 binding site, the expression of GAL4-Pax6 restored glucagon promoter activity and PPARgamma responsiveness. GAL4-Pax6 transcriptional activity was inhibited by PPARgamma in response to thiazolidinedione treatment also at a minimal viral promoter. These results suggest that PPARgamma in a ligand-dependent but DNA binding-independent manner inhibits Pax6 transcriptional activity, resulting in inhibition of glucagon gene transcription. These data thereby define Pax6 as a novel functional target of PPARgamma and suggest that inhibition of glucagon gene expression may be among the multiple mechanisms through which thiazolidinediones improve glycemic control in diabetic subjects.