Anoctamin 1 antagonism potentiates conventional tocolytic-mediated relaxation of pregnant human uterine smooth muscle.

BACKGROUND: Currently available tocolytic agents are not effective treatment for preterm labor beyond 48 h. A major reason is the development of maternal side effects which preclude the maintenance of an effective steady-state drug concentration. One strategy that can mitigate these side effects is utilizing synergistic drug combinations to reduce the drug concentrations necessary to elicit a clinical effect. We have previously shown that three anoctamin 1 (ANO1) antagonists mediate potent relaxation of precontracted human uterine smooth muscle (USM). In this study, we aimed to determine whether a combination of sub-relaxatory doses of tocolytic drugs in current clinical use [the L-type voltage-gated calcium channel (VGCC) blocker, nifedipine (NIF); and the ß2-adrenergic (ß2AR) agonist, terbutaline (TRB)] will potentiate USM relaxation with two ANO1 antagonists [benzbromarone (BB) and MONNA (MN)]. OBJECTIVE: This study sought to examine the synergistic potency and mechanistic basis of two ANO1 antagonists with currently available tocolytic drugs. Functional endpoints assessed included relaxation of pre-contracting pregnant human USM tissue, inhibition of intracellular calcium release, and reduction of spontaneous transient inward current (STIC) recordings in human uterine smooth muscle cells. METHODS: Human myometrial strips and primary human USM cells were used in organ bath and calcium flux experiments with different combinations of sub-threshold doses of ANO1 antagonists and terbutaline or nifedipine to determine if ANO1 antagonists potentiate tocolytic drugs. RESULTS: The combination of sub-threshold doses of two ANO1 antagonists and current tocolytic drugs demonstrate a significant degree of synergy to relax human pregnant USM compared to the effects achieved when these drugs are administered individually. CONCLUSION: A combination of sub-threshold doses of VGCC blocker and ß2AR agonist with ANO1 antagonists potentiates relaxation of oxytocin-induced contractility and calcium flux in human USM ex vivo. Our findings may serve as a foundation for novel tocolytic drug combinations.

On the Mechanism of Self-Assembly by a Hydrogel-Forming Peptide.

Self-assembling peptide-based hydrogels are a class of tunable soft materials that have been shown to be highly useful for a number of biomedical applications. The dynamic formation of the supramolecular fibrils that compose these materials has heretofore remained poorly characterized. A better understanding of this process would provide important insights into the behavior of these systems and could aid in the rational design of new peptide hydrogels. Here, we report the determination of the microscopic steps that underpin the self-assembly of a hydrogel-forming peptide, SgI37-49. Using theoretical models of linear polymerization to analyze the kinetic self-assembly data, we show that SgI37-49 fibril formation is driven by fibril-catalyzed secondary nucleation and that all the microscopic processes involved in SgI37-49 self-assembly display an enzyme-like saturation behavior. Moreover, this analysis allows us to quantify the rates of the underlying processes at different peptide concentrations and to calculate the time evolution of these reaction rates over the time course of self-assembly. We demonstrate here a new mechanistic approach for the study of self-assembling hydrogel-forming peptides, which is complementary to commonly used materials science characterization techniques.

Uncovering protein-protein interactions through a team-based undergraduate biochemistry course.

How can we provide fertile ground for students to simultaneously explore a breadth of foundational knowledge, develop cross-disciplinary problem-solving skills, gain resiliency, and learn to work as a member of a team? One way is to integrate original research in the context of an undergraduate biochemistry course. In this Community Page, we discuss the development and execution of an interdisciplinary and cross-departmental undergraduate biochemistry laboratory course. We present a template for how a similar course can be replicated at other institutions and provide pedagogical and research results from a sample module in which we challenged our students to study the binding interface between 2 important biosynthetic proteins. Finally, we address the community and invite others to join us in making a larger impact on undergraduate education and the field of biochemistry by coordinating efforts to integrate research and teaching across campuses.

Metabolic tracing analysis reveals substrate-specific metabolic deficits in platelet storage lesion.

BACKGROUND: Storage of platelets (PLTs) results in a progressive defect termed PLT storage lesion (PSL). The PSL is characterized by poor PLT quality on a variety of assays. Metabolic defects are thought to underlie the PSL; thus this study was designed to quantitatively probe specific metabolic pathways over PLT storage. STUDY DESIGN AND METHODS: Relative incorporation of stable isotope-labeled substrates was quantified by isotopologue analysis of key acyl-coenzyme A (CoA) thioester products for fresh, viable (after collection, Days 2-5), and expired PLTs (after Day 5). We examined the incorporation of acetate, glucose, and palmitate into acetyl- and succinyl-CoA via liquid chromatography-tandem mass spectrometry. RESULTS: Storage-related defects in the incorporation of acetyl-CoA derived from acetate and palmitate were observed. Carbon derived from palmitate and acetate in succinyl-CoA was reduced over storage time. Glucose incorporation into succinyl-CoA increased in viable PLTs and then decreased in expired PLTs. Carbon derived from octanoate and pyruvate remained partially able to incorporate into acetyl- and succinyl-CoA in expired PLTs, with high variability in pyruvate incorporation. CONCLUSION: Isotopologue analysis is useful in probing substrate specific defects in the PSL.

LC-MS Analysis of Human Platelets as a Platform for Studying Mitochondrial Metabolism.

Perturbed mitochondrial metabolism has received renewed interest as playing a causative role in a range of diseases. Probing alterations to metabolic pathways requires a model in which external factors can be well controlled, allowing for reproducible and meaningful results. Many studies employ transformed cellular models for these purposes; however, metabolic reprogramming that occurs in many cancer cell lines may introduce confounding variables. For this reason primary cells are desirable, though attaining adequate biomass for metabolic studies can be challenging. Here we show that human platelets can be utilized as a platform to carry out metabolic studies in combination with liquid chromatography-tandem mass spectrometry analysis. This approach is amenable to relative quantification and isotopic labeling to probe the activity of specific metabolic pathways. Availability of platelets from individual donors or from blood banks makes this model system applicable to clinical studies and feasible to scale up. Here we utilize isolated platelets to confirm previously identified compensatory metabolic shifts in response to the complex I inhibitor rotenone. More specifically, a decrease in glycolysis is accompanied by an increase in fatty acid oxidation to maintain acetyl-CoA levels. Our results show that platelets can be used as an easily accessible and medically relevant model to probe the effects of xenobiotics on cellular metabolism.

Comprehensive curation and analysis of fungal biosynthetic gene clusters of published natural products.

Microorganisms produce a wide range of natural products (NPs) with clinically and agriculturally relevant biological activities. In bacteria and fungi, genes encoding successive steps in a biosynthetic pathway tend to be clustered on the chromosome as biosynthetic gene clusters (BGCs). Historically, "activity-guided" approaches to NP discovery have focused on bioactivity screening of NPs produced by culturable microbes. In contrast, recent "genome mining" approaches first identify candidate BGCs, express these biosynthetic genes using synthetic biology methods, and finally test for the production of NPs. Fungal genome mining efforts and the exploration of novel sequence and NP space are limited, however, by the lack of a comprehensive catalog of BGCs encoding experimentally-validated products. In this study, we generated a comprehensive reference set of fungal NPs whose biosynthetic gene clusters are described in the published literature. To generate this dataset, we first identified NCBI records that included both a peer-reviewed article and an associated nucleotide record. We filtered these records by text and homology criteria to identify putative NP-related articles and BGCs. Next, we manually curated the resulting articles, chemical structures, and protein sequences. The resulting catalog contains 197 unique NP compounds covering several major classes of fungal NPs, including polyketides, non-ribosomal peptides, terpenoids, and alkaloids. The distribution of articles published per compound shows a bias toward the study of certain popular compounds, such as the aflatoxins. Phylogenetic analysis of biosynthetic genes suggests that much chemical and enzymatic diversity remains to be discovered in fungi. Our catalog was incorporated into the recently launched Minimum Information about Biosynthetic Gene cluster (MIBiG) repository to create the largest known set of fungal BGCs and associated NPs, a resource that we anticipate will guide future genome mining and synthetic biology efforts toward discovering novel fungal enzymes and metabolites.

Production of stable isotope-labeled acyl-coenzyme A thioesters by yeast stable isotope labeling by essential nutrients in cell culture.

Acyl-coenzyme A (CoA) thioesters are key metabolites in numerous anabolic and catabolic pathways, including fatty acid biosynthesis and ß-oxidation, the Krebs cycle, and cholesterol and isoprenoid biosynthesis. Stable isotope dilution-based methodology is the "gold standard" for quantitative analyses by mass spectrometry. However, chemical synthesis of families of stable isotope-labeled metabolites such as acyl-CoA thioesters is impractical. Previously, we biosynthetically generated a library of stable isotope internal standard analogs of acyl-CoA thioesters by exploiting the essential requirement in mammals and insects for pantothenic acid (vitamin B5) as a metabolic precursor for the CoA backbone. By replacing pantothenic acid in the cell medium with commercially available [(13)C3(15)N1]-pantothenic acid, mammalian cells exclusively incorporated [(13)C3(15)N1]-pantothenate into the biosynthesis of acyl-CoA and acyl-CoA thioesters. We have now developed a much more efficient method for generating stable isotope-labeled CoA and acyl-CoAs from [(13)C3(15)N1]-pantothenate using stable isotope labeling by essential nutrients in cell culture (SILEC) in Pan6-deficient yeast cells. Efficiency and consistency of labeling were also increased, likely due to the stringently defined and reproducible conditions used for yeast culture. The yeast SILEC method greatly enhances the ease of use and accessibility of labeled CoA thioesters and also provides proof of concept for generating other labeled metabolites in yeast mutants.

Application of tissue mesodissection to molecular cancer diagnostics.

AIMS: To demonstrate clinical application of a mesodissection platform that was developed to combine advantages of laser-based instrumentation with the speed/ease of manual dissection for automated dissection of tissue off standard glass slides. METHODS: Genomic analysis for KRAS gene mutation was performed on formalin fixed paraffin embedded (FFPE) cancer patient tissue that was dissected using the mesodissection platform. Selected reaction monitoring proteomic analysis for quantitative Her2 protein expression was performed on FFPE patient tumour tissue dissected by a laser-based instrument and the MilliSect instrument. RESULTS: Genomic analysis demonstrates highly confident detection of KRAS mutation specifically in lung cancer cells and not the surrounding benign, non-tumour tissue. Proteomic analysis demonstrates Her2 quantitative protein expression in breast cancer cells dissected manually, by laser-based instrumentation and by MilliSect instrumentation (mesodissection). CONCLUSIONS: Slide-mounted tissue dissection is commonly performed using laser-based instruments or manually scraping tissue by scalpel. Here we demonstrate that the mesodissection platform as performed by the MilliSect instrument for tissue dissection is cost-effective; it functions comparably to laser-based dissection and which can be adopted into a clinical diagnostic workflow.

Transcontinental telementoring with pediatric surgeons: proof of concept and technical considerations.

PURPOSE: To evaluate different technologies that can facilitate telementoring in a variety of pediatric surgical procedures. MATERIALS AND METHODS: Two different telementoring technologies were used to provide two-way audio and visual communication between experienced pediatric surgeon mentors located in another city and less experienced trainees performing a surgical procedure. The first technology consisted of store-bought equipment that connected the operating room laparoscope to a Skype™ (Microsoft, Redmond, WA) connection (used in 1 case), whereas the second was a proprietary telementoring robot, Karl Storz Endoscopy-America, Inc. VisitOR1(®) (Karl Storz GmbH & Co. KG, Tuttlingen, Germany) (used in 5 cases). The procedures included a video-assisted thoracic surgery lower lobectomy, a temporary and two permanent gastric stimulator placements, and two laparoscopic inguinal hernia repairs and were performed by pediatric surgeons (3 cases), a pediatric gastroenterologist (1 case), and a general surgeon (2 cases) under the guidance of pediatric surgeon mentors. RESULTS: All procedures were completed successfully in a time-efficient manner, without loss of transmission and without complications. Although the Skype technology was less costly, it lacked telestrator capacity and was not adequately secure. The VisitOR1 telementoring robot enabled high-resolution video communication, had telestrator capacity, and allowed pointing during the procedure. The mentors assisted with trocar placement, modifying the surgical technique, identifying planes of dissection, and indicating locations of device and suture placement. CONCLUSIONS: Telementoring is a useful adjunct in the field of pediatric surgery that can aid in the transfer of surgical skills remotely and shorten the time to implementation of new surgical techniques into practice. Optimal telementoring technology should have a secure wireless connection, high video resolution, and minimal bandwidth latency.

A gel electrophoresis loading system to prevent laboratory contamination by amplification products.

Pipet tip loading of polymerase chain reaction (PCR) and other amplification products into an electrophoresis gel represents a potential source of laboratory contamination. We have developed a prototype of the gel contamination control system (GelCCS) that enables gel loading by bottom puncture of PCR tubes. Puncture occurs within a sealed gel casing, preventing contamination of the surrounding environment. The system was designed for inexpensive manufacture so that after the results are visualized, the gel casing and PCR tubes are discarded intact with the amplification products sealed inside. We demonstrate that gel loading is reliable and that the resulting bands are equivalent in appearance to manually loaded gels.

A mill based instrument and software system for dissecting slide-mounted tissue that provides digital guidance and documentation.

BACKGROUND: Dissection of specific Areas Of Interest (AOIs) of slide-mounted tumor samples is often used to enrich for cancer cells in order to generate better signal to noise ratios in subsequent biochemical characterization. Most clinical laboratories utilize manual dissection for practical reasons and to avoid the expense and difficulties of laser microdissection systems. Unfortunately, manual methods often lack resolution and process documentation. The goal of this project was to design a dissection system for slide-mounted tissue with better precision than manual methods that also provides digital image guidance and electronic process documentation. METHODS: An instrument that is essentially a micro tissue mill was developed. It employs a specialized disposable mill bit that simultaneously dispenses liquid, cuts tissue from the slide surface, and aspirates the liquid along with the displaced tissue fragments. A software package was also developed that is capable of transferring digitally annotated AOIs between images of serially cut tissue sections to guide dissection and generate an electronic record of the process. RESULTS: The performance of this "meso" dissection system was tested using post dissection visual examination for resolution and accuracy, fluorescence based DNA quantitation for recovery efficiency, and dissection of closely situated mouse-human tissue sections followed by PCR amplification for purity determination. The minimum resolution is a dissected circle smaller than 200 microns in diameter, edge dissection accuracy is tighter than 100 microns, recovery efficiency appears greater than 95%, and recovery purity is greater than 99% relative to a different tissue located 100 microns from the dissection boundary. The system can dissect from both paraffinized and deparaffinized FFPE tissue sections that are mounted on plain glass slides, and it is compatible with DNA, RNA, and protein isolation. CONCLUSIONS: The mesodissection system is an effective alternative to manual dissection methods and is applicable for biomarker analysis of anatomical pathology samples, where enrichment of AOIs from the tissue section is helpful, but pure cell populations are not required.

Need for subsequent fundoplication after gastrostomy based on patient characteristics.

BACKGROUND: Gastrostomy tube placement is common in children. Many of the conditions associated with need for gastrostomy are also associated with gastroesophageal reflux. It is not clear how many patients without complicated reflux will subsequently require a fundoplication or which conditions increase this risk. Therefore, we performed a two-center review to determine the disease-specific propensity for fundoplication after gastrostomy tube placement. METHODS: The data set was retrospectively collected from two centers from 2000 to 2008. All patients underwent gastrostomy tube placement without fundoplication owing to the surgeon's discernment that fundoplication was not needed at the time. Pearson's correlation was used to evaluate the influence of patient variables and operative approach against the subsequent need for fundoplication. Significance was defined as two-tailed P ≤ 0.01. Logistic regression analysis was used to evaluate independence. RESULTS: A total of 684 patients underwent gastrostomy tube placement only, of which 124 were open, 282 laparoscopic, and 278 endoscopic (percutaneous endoscopic gastrostomy). The mean patient age was 2.9 years. Subsequent fundoplication was performed in 62 patients (9.1%). The mean interval to fundoplication was 20.7 months. Cerebral palsy and anoxic brain injury had the most significant correlation with subsequent fundoplication. These were also independent predictors. The laparoscopic approach had a negative correlation with the subsequent need for fundoplication. CONCLUSIONS: The low incidence of subsequent fundoplication in children who undergo gastrostomy tube placement justifies conservative use of fundoplication in the absence of complicated reflux. Those with cerebral palsy and anoxic brain injury appeared to have the greatest risk of the need for subsequent fundoplication.

Ulcerative colitis of the neovagina as a postsurgical complication of persistent cloaca.

Persistent cloaca is characterized by a common vestibule connected to the bladder, uterus, and rectum and a single perineal orifice to the exterior. Treatment can involve vaginal reconstruction with sigmoid/descending colon. We report a case of an 8-year-old girl who, as an infant, underwent vaginoplasty using sigmoid colon for persistent cloaca and developed a fulminant colitis that also affected the colonic neovagina 2 years after her reconstruction.

Costal osteochondroma causing pneumothorax in an adolescent: a case report and review of the literature.

Costal osteochondroma is a rare but important condition to recognize because of the possibility of serious consequences if not diagnosed and treated promptly. Patients can present with numerous complications, including hemothorax, pneumothorax, nervous or vascular impingement, and fracture. We report the case of a 17-year-old adolescent boy who presented to the pediatrician with intermittent shortness of breath and pleuritic chest pain. A chest x-ray demonstrated a left-sided pneumothorax and triangular opacity in the left chest. A computed tomographic scan of the chest revealed the cause to be a costal exostosis of the anterior fifth rib. The lesion was excised using video-assisted thoracoscopic surgery, which has become an increasingly popular method for treating these lesions, causing significantly less morbidity and allowing for a faster recovery than a major thoracotomy.

The endoscopic U-stitch technique for primary button placement: an institution's experience.

BACKGROUND: Various gastrostomy tube placement techniques have been reported in the literature. The endoscopic U-stitch technique allows for primary button placement without the need for laparoscopy. The purpose of this study was to quantify the completion rate and the occurrence of complications with this procedure at one academic teaching hospital. METHODS: All gastrostomy procedures between February 2001 and September 2008 were reviewed. Data were collected from paper and electronic records for endoscopic U-stitch procedures. RESULTS: Endoscopic U-stitch gastrostomies were attempted in 121 patients, with primary button placement in 115 (95%) and conversion to an open procedure in 6. No procedure-related deaths occurred, and 7% of patients experienced postoperative complications that included hematemesis, cellulitis, colonic perforation, granulation tissue requiring operative excision, and surgical fistula closure. Average operative time was 18 min. CONCLUSION: The endoscopic U-stitch technique is safe and allows for primary button placement in infants and children. Its complication rate compares favorably with other laparoscopic and open techniques described in the literature.

Early experience with single-port laparoscopic surgery in children.

INTRODUCTION: The current paradigm in laparoscopic surgery is for each instrument to enter the abdomen through its own separate incision. The advent of newer laparoscopic trocars and instruments now allows for all instruments to enter through a single incision. This may lead to less pain and improved cosmetic outcome. Single-incision laparoscopic surgery (SILS) has recently been described in adults. In this article, we report our preliminary experience of SILS in children. METHODS: A retrospective review was performed of the operative database at Rainbow Babies and Children's Hospital (Cleveland, OH) from March 2008 to March 2009, looking for all cases that were performed through a single laparoscopic incision. RESULTS: A total of 72 SILS cases were performed. These included cholecystectomy, splenectomy, intussusception reduction, gastrostomy tube placement, thoracoscopic lung biopsy, thoracoscopic decortication, and appendectomy. Five appendectomies were converted to traditional three-port laparoscopy. There were two umbilical wound infections after an appendectomy. There were no other complications. CONCLUSION: Preliminary experience with SILS in children appears to be safe and effective. Greater numbers and a prospective trial will be necessary to assess the true benefit of this approach.

Short-term natural history of the standard approaches for gastrostomy tube placement in the pediatric patient.

INTRODUCTION: Gastrostomy placement is a common procedure in the pediatric population. Standard approaches of tube placement include open, laparoscopic, and percutaneous endoscopic methods. Placement of the gastrostomy in relation to the fundus and the anterior abdominal wall is crucial to ensure adequate comfort and functionality. Misplacement may require repositioning of the gastrostomy, the rate of which has not been well documented. We, therefore, have reviewed a multi-institutional experience with gastrostomy tube placement to determine the short-term natural history of placement, based on approach, and to establish a cohort to determine the long-term natural history. METHODS: We conducted a retrospective review of all pediatric patients who underwent percutaneous endoscopic, laparoscopic, or open gastrostomy placement at two institutions from 2000 to 2008. RESULTS: There were a total of 1534 patients who underwent gastrostomy tube placement during this time period. The most common procedure was fundoplication with gastrostomy (N = 832), followed by gastrostomy alone (N = 420), and then percutaneous endoscopic gastrostomy (PEG) (N = 285). There were 4 (0.3%) gastrostomy tubes that required repositioning to a new site due to encroachment upon the rib margin. Two were open and 2 were PEG (P > 0.99). Twenty of 39 patients who had an open fundoplication following gastrostomy had the gastrostomy taken down during the procedure, compared to 5 of 31 patients (P = 0.03), who underwent laparoscopic fundoplication following gastrostomy. CONCLUSIONS: These data demonstrate that the need for gastrostomy tube repositioning is rare in the short term, regardless of approach, although a takedown of the gastrostomy is more likely when an open fundoplication is performed.

Carbonates, thiocarbonates, and the corresponding monoalkyl derivatives: III. The 13C chemical shift tensors in potassium carbonate, bicarbonate and related monomethyl derivatives.

The principal values of the 13C chemical shift tensors in potassium carbonate (K2CO3), trithiocarbonate (K2CS3), bicarbonate (KHCO3), methylcarbonate (KO2COCH3), S-methyl-monothiocarbonate (KO2CSCH3), O-methyl-monothiocarbonate (KOSCOCH3), S-methyl-dithiocarbonate (KOSCSCH3), and O-methyl-dithiocarbonate (KS2COCH3), were measured in solid-state nuclear magnetic resonance experiments. Chemical shift tensor calculations on the corresponding isolated anions were used to assign the chemical shift tensor orientations in the molecular frames of all anions. The correlation between experimental and calculated principal values improves significantly when the calculations are performed on isolated anions with proton-optimized X-ray geometries rather than on isolated anions with fully optimized geometries. Further considerable improvement in the correlation is achieved by utilizing the embedded ion method, which was recently developed to include electrostatic crystal potentials in chemical shift tensor calculations on ionic compounds. Similarities and differences in the chemical shift tensor orientations and principal values of the trigonal sp2 carbon atoms in the carbonate and thiocarbonate anions are compared with those known for condensed polyaromatic hydrocarbons.