Matrisome and Immune Pathways Contribute to Extreme Vascular Outcomes in Williams-Beuren Syndrome

BACKGROUND

Supravalvar aortic stenosis (SVAS) is a characteristic feature of Williams-Beuren syndrome (WBS). Its severity varies: ~20% of people with Williams-Beuren syndrome have SVAS requiring surgical intervention, whereas ~35% have no appreciable SVAS. The remaining individuals have SVAS of intermediate severity. Little is known about genetic modifiers that contribute to this variability.

METHODS AND RESULTS

We performed genome sequencing on 473 individuals with Williams-Beuren syndrome and developed strategies for modifier discovery in this rare disease population. Approaches include extreme phenotyping and nonsynonymous variant prioritization, followed by gene set enrichment and pathway-level association tests. We next used GTEx v8 and proteomic data sets to verify expression of candidate modifiers in relevant tissues. Finally, we evaluated overlap between the genes/pathways identified here and those ascertained through larger aortic disease/trait genome-wide association studies. We show that SVAS severity in Williams-Beuren syndrome is associated with increased frequency of common and rarer variants in matrisome and immune pathways. Two implicated matrisome genes (ACAN and LTBP4) were uniquely expressed in the aorta. Many genes in the identified pathways were previously reported in genome-wide association studies for aneurysm, bicuspid aortic valve, or aortic size.

CONCLUSIONS

Smaller sample sizes in rare disease studies necessitate new approaches to detect modifiers. Our strategies identified variation in matrisome and immune pathways that are associated with SVAS severity. These findings suggest that, like other aortopathies, SVAS may be influenced by the balance of synthesis and degradation of matrisome proteins. Leveraging multiomic data and results from larger aorta-focused genome-wide association studies may accelerate modifier discovery for rare aortopathies like SVAS.

Loss of Baz1b in mice causes perinatal lethality, growth failure, and variable multi-system outcomes

BAZ1B is one of 25-27 coding genes deleted in canonical Williams syndrome, a multi-system disorder causing slow growth, vascular stenosis, and gastrointestinal complaints, including constipation. BAZ1B is involved in (among other processes) chromatin organization, DNA damage repair, and mitosis, suggesting reduced BAZ1B may contribute to Williams syndrome symptoms. In mice, loss of Baz1b causes early neonatal death. 89.6% of Baz1b-/- mice die within 24 h of birth without vascular anomalies or congenital heart disease (except for patent ductus arteriosus). Some (<50%) Baz1b-/- were noted to have prolonged neonatal cyanosis, patent ductus arteriosus, or reduced lung aeration, and none developed a milk spot. Meanwhile, 35.5% of Baz1b+/- mice die over the first three weeks after birth. Surviving Baz1b heterozygotes grow slowly (with variable severity). 66.7% of Baz1b+/- mice develop bowel dilation, compared to 37.8% of wild-type mice, but small bowel and colon transit studies were normal. Additionally, enteric neuron density appeared normal in Baz1b-/- mice except in distal colon myenteric plexus, where neuron density was modestly elevated. Combined with several rare phenotypes (agnathia, microphthalmia, bowel dilation) recovered, our work confirms the importance of BAZ1B in survival and growth and suggests that reduced copy number of BAZ1B may contribute to the variability in Williams syndrome phenotypes.

Carbon-to-nitrogen single-atom transmutation of azaarenes

When searching for the ideal molecule to fill a particular functional role (for example, a medicine), the difference between success and failure can often come down to a single atom1. Replacing an aromatic carbon atom with a nitrogen atom would be enabling in the discovery of potential medicines2, but only indirect means exist to make such C-to-N transmutations, typically by parallel synthesis3. Here, we report a transformation that enables the direct conversion of a heteroaromatic carbon atom into a nitrogen atom, turning quinolines into quinazolines. Oxidative restructuring of the parent azaarene gives a ring-opened intermediate bearing electrophilic sites primed for ring reclosure and expulsion of a carbon-based leaving group. Such a 'sticky end' approach subverts existing atom insertion-deletion approaches and as a result avoids skeleton-rotation and substituent-perturbation pitfalls common in stepwise skeletal editing. We show a broad scope of quinolines and related azaarenes, all of which can be converted into the corresponding quinazolines by replacement of the C3 carbon with a nitrogen atom. Mechanistic experiments support the critical role of the activated intermediate and indicate a more general strategy for the development of C-to-N transmutation reactions.

Core-Labeling (Radio) Synthesis of Phenols

We report a method that enables the fast incorporation of carbon isotopes into the ipso carbon of phenols. Our approach relies on the synthesis of a 1,5-dibromo-1,4-pentadiene precursor, which upon lithium-halogen exchange followed by treatment with carbonate esters results in a formal [5 + 1] cyclization to form the phenol product. Using this strategy, we have prepared 12 1-13C-labeled phenols, show proof-of-concept for the labeling of phenols with carbon-14, and demonstrate phenol synthesis directly from cyclotron-produced [11C]CO2.

Novel ophthalmic findings and deep phenotyping in Williams-Beuren syndrome

BACKGROUND/AIMS

To characterise the ocular manifestations of Williams-Beuren syndrome (WBS) and compare these to patients with isolated elastin mediated supravalvular aortic stenosis (SVAS).

METHODS

Fifty-seven patients with a diagnosis of WBS and five with SVAS underwent comprehensive ophthalmic evaluation at the National Institutes of Health from 2017 to 2020, including best-corrected visual acuity, slit-lamp biomicroscopy, optical biometry, dilated fundus examination, optical coherence tomography and colour fundus imaging.

RESULTS

Mean age of the 57 WBS patients was 20.3 years (range 3-60 years). Best-corrected visual acuity ranged from 20/20 to 20/400 with mean spherical equivalent near plano OU. Twenty-four eyes (21.8%) had an axial length (AL) less than 20.5 mm and 38 eyes (34.5%) had an AL measuring 20.5-22.0 mm. Stellate iris and retinal arteriolar tortuosity were noted in 30 (52.6%) and 51 (89.5%) WBS patients, respectively. Novel retinal findings in WBS included small hypopigmented retinal deposits (OD 29/57, OS 27/57) and broad foveal pit contour (OD 44/55, OS 42/51). Of the five patients with SVAS, none had stellate iris or broad foveal pit contour while 2/5 had retinal arteriolar tortuosity.

CONCLUSION

WBS is a complex multisystem genetic disorder with diverse ophthalmic findings that differ from those seen in isolated elastin mediated SVAS. These results suggest other genes within the WBS critical region, aside from ELN, may be involved in observed ocular phenotypes and perhaps broader ocular development. Furthermore, retinal arteriolar tortuosity may provide future insight into systemic vascular findings in WBS.

Aromatic nitrogen scanning by ipso-selective nitrene internalization

Nitrogen scanning in aryl fragments is a valuable aspect of the drug discovery process, but current strategies require time-intensive, parallel, bottom-up synthesis of each pyridyl isomer because of a lack of direct carbon-to-nitrogen (C-to-N) replacement reactions. We report a site-directable aryl C-to-N replacement reaction allowing unified access to various pyridine isomers through a nitrene-internalization process. In a two-step, one-pot procedure, aryl azides are first photochemically converted to 3H-azepines, which then undergo an oxidatively triggered C2-selective cheletropic carbon extrusion through a spirocyclic azanorcaradiene intermediate to afford the pyridine products. Because the ipso carbon of the aryl nitrene is excised from the molecule, the reaction proceeds regioselectively without perturbation of the remainder of the substrate. Applications are demonstrated in the abbreviated synthesis of a pyridyl derivative of estrone, as well as in a prototypical nitrogen scan.

A focus on 1-azahomocubane: the new kid on the block

Strained hydrocarbons have recently regained interest as potential drug candidates. However, the study of their heteroatom analogs has remained limited, despite differing by only a single atom. The first synthesis of 1-azahomocubane by Williams, Eaton and co-workers (T. Fahrenhorst-Jones et al., Chem. Sci., 2023, 14, 2821-2825, https://doi.org/10.1039/D3SC00001J) is discussed within the context of nitrogen scanning of strained hydrocarbons.

Heart Rate Variability Analysis May Identify Individuals With Williams-Beuren Syndrome at Risk of Sudden Death

BACKGROUND

Williams-Beuren syndrome (WBS) (Online Mendelian Inheritance in Man #194050) is a rare genetic multisystem disorder resulting from a chromosomal microdeletion at 7q11.23. The condition is characterized by distinct facies, intellectual disability, and supravalvar aortic stenosis. Those with WBS have an increased risk of sudden death, but mechanisms underlying this phenotype are incompletely understood.

OBJECTIVES

The aim of this study was to quantify and compare autonomic activity as reflected by heart rate variability (HRV) measures in a cohort of individuals with WBS (n = 18) and age- and sex-matched control subjects (n = 18).

METHODS

We performed HRV analysis on 24-hour electrocardiography recordings using nonlinear, time and frequency domain analyses on a cohort of subjects with WBS and age- and sex-matched control subjects enrolled in a prospective cross-sectional study designed to characterize WBS disease natural history.

RESULTS

WBS subjects demonstrated diminished HRV (reflected by the SD of the NN intervals [P = 0.0001], SD of the average NN interval for 5-minute intervals over 24 hours [P < 0.0001], average of the 5-minute SDs of NN intervals for 24 hours [P = 0.0002], root mean square of successive differences of NN intervals [P = 0.0004], short axis of the Poincaré plot (SD1) [P < 0.0001], and long axis of the Poincaré plot [P < 0.0001]) and indirect markers of parasympathetic activity (reflected by the percent of NN intervals different from previous by 50% or more of local average [P < 0.0007], root mean square of successive differences of NN intervals [P = 0.0004], natural log high-frequency power [P = 0.0038], and SD1 [P < 0.0001]). Additional parameters were also significantly different, including natural log very low-frequency power (decreased; P = 0.0002), natural log low-frequency power (decreased; P = 0.0024), and SD1 divided by the long axis of the Poincaré plot (decreased; P < 0.0001).

CONCLUSIONS

Individuals with WBS demonstrate significant HRV abnormalities consistent with diminished autonomic reserve. Future studies will be needed to determine the relationship between autonomic dysregulation observed and sudden death risk seen in these patients. (Impact of Elastin Mediated Vascular Stiffness on End Organs; NCT02840448).

Direct Deaminative Functionalization

Selective functional group interconversions in complex molecular settings underpin many of the challenges facing modern organic synthesis. Currently, a privileged subset of functional groups dominates this landscape, while others, despite their abundance, are sorely underdeveloped. Amines epitomize this dichotomy; they are abundant but otherwise intransigent toward direct interconversion. Here, we report an approach that enables the direct conversion of amines to bromides, chlorides, iodides, phosphates, thioethers, and alcohols, the heart of which is a deaminative carbon-centered radical formation process using an anomeric amide reagent. Experimental and computational mechanistic studies demonstrate that successful deaminative functionalization relies not only on outcompeting the H-atom transfer to the incipient radical but also on the generation of polarity-matched, productive chain-carrying radicals that continue to react efficiently. The overall implications of this technology for interconverting amine libraries were evaluated via high-throughput parallel synthesis and applied in the development of one-pot diversification protocols.

A Synthetic Cycle for Heteroarene Synthesis by Nitride Insertion

Recent interest in skeletal editing necessitates the continued development of reagent classes with the ability to transfer single atoms. Terminal transition metal nitrides hold immense promise for single-atom transfer, though their use in organic synthesis has so far been limited. Here we demonstrate a synthetic cycle with associated detailed mechanistic studies that primes the development of terminal transition metal nitrides as valuable single-atom transfer reagents. Specifically, we show [cis-terpyOsNCl₂ ]PF₆ inserts nitrogen into indenes to afford isoquinolines. Mechanistic studies for each step (insertion, aromatization, product release, and nitride regeneration) are reported, including crystallographic characterization of diverted intermediates, kinetics, and computational studies. The mechanistic foundation set by this synthetic cycle opens the door to the further development of nitrogen insertion heteroarene syntheses promoted by late transition metal nitrides.

Unified Access to Pyrimidines and Quinazolines Enabled by N-N Cleaving Carbon Atom Insertion

Given the ubiquity of heterocycles in biologically active molecules, transformations with the capacity to modify such molecular skeletons with modularity remain highly desirable. Ring expansions that enable interconversion of privileged heterocyclic motifs are especially interesting in this regard. As such, the known mechanisms for ring expansion and contraction determine the classes of heterocycle amenable to skeletal editing. Herein, we report a reaction that selectively cleaves the N–N bond of pyrazole and indazole cores to afford pyrimidines and quinazolines, respectively. This chlorodiazirine-mediated reaction provides a unified route to a related pair of heterocycles that are otherwise typically prepared by divergent approaches. Mechanistic experiments and DFT calculations support a pathway involving pyrazolium ylide fragmentation followed by cyclization of the ring-opened diazahexatriene intermediate to yield the new diazine core. Beyond enabling access to valuable heteroarenes from easily prepared starting materials, we demonstrate the synthetic utility of skeletal editing in the synthesis of a Rosuvastatin analog as well as in an aryl vector-adjusting direct scaffold hop.

Airflow Obstruction in Adults with Williams Syndrome and Mice with Elastin Insufficiency

Williams−Beuren syndrome (WS) results from the deletion of 25−27 coding genes, including elastin (ELN), on human chromosome 7q11.23. Elastin provides recoil to tissues; emphysema and chronic obstructive pulmonary disease have been linked to its destruction. Consequently, we hypothesized that elastin insufficiency would predispose to obstructive features. Twenty-two adults with WS (aged 18−55) and controls underwent pulmonary function testing, 6 min walk, and chest computed tomography (CT). Lung and airspace dimensions were assessed in Eln+/− and control mice via microCT and histology. The forced expiratory volume in 1 s (FEV1) and the ratio of FEV1 to forced vital capacity (FVC) were lower in adults with WS (p < 0.0001 and p < 0.05, respectively). The FEV1/FVC ratio was more frequently below the lower limit of normal in cases (p < 0.01). The ratio of residual volume to total lung capacity (RV/TLC, percent predicted) was higher in cases (p < 0.01), suggesting air trapping. People with WS showed reduced exercise capacity (p < 0.0001). In Eln+/− mice, ex vivo lung volumes were increased (p < 0.0001), with larger airspaces (p < 0.001). Together these data show that elastin insufficiency impacts lung physiology in the form of increased air trapping and obstruction, suggesting a role for lung function monitoring in adults with WS.

Elastin Insufficiency Confers Proximal and Distal Pulmonary Vasculopathy in Mice, Partially Remedied by the KATP Channel Opener Minoxidil: Considerations and Cautions for the Treatment of People With Williams-Beuren Syndrome

Background

Williams Beuren syndrome (WBS) is a recurrent microdeletion disorder that removes one copy of elastin (ELN), resulting in large artery vasculopathy. Early stenosis of the pulmonary vascular tree is common, but few data are available on longer-term implications of the condition.

Methods

Computed tomography (CT) angiogram (n = 11) and echocardiogram (n = 20) were performed in children with WBS aged 3.4–17.8 years. Controls (n = 11, aged 4.4–16.8 years) also underwent echocardiogram. Eln^+/− mice were analyzed by invasive catheter, echocardiogram, micro-CT (μCT), histology, and pressure myography. We subsequently tested whether minoxidil resulted in improved pulmonary vascular endpoints.

Results

WBS participants with a history of main or branch pulmonary artery (PA) stenosis requiring intervention continued to exhibit increased right ventricular systolic pressure (RVSP, echocardiogram) relative to their peers without intervention (p < 0.01), with no clear difference in PA size. Untreated Eln^+/− mice also show elevated RVSP by invasive catheterization (p < 0.0001), increased normalized right heart mass (p < 0.01) and reduced caliber branch PAs by pressure myography (p < 0.0001). Eln^+/− main PA medias are thickened histologically relative to Eln^+/+ (p < 0.0001). Most Eln^+/− phenotypes are shared by both sexes, but PA medial thickness is substantially greater in Eln^+/− males (p < 0.001). Eln^+/− mice showed more acute proximal branching angles (p < 0.0001) and longer vascular segment lengths (p < 0.0001) (μCT), with genotype differences emerging by P7. Diminished PA acceleration time (p < 0.001) and systolic notching (p < 0.0001) were also observed in Eln^+/− echocardiography. Vascular casting plus μCT revealed longer generation-specific PA arcade length (p < 0.0001), with increased PA branching detectable by P90 (p < 0.0001). Post-weaning minoxidil decreased RVSP (p < 0.01) and normalized PA caliber (p < 0.0001) but not early-onset proximal branching angle or segment length, nor later-developing peripheral branch number.

Conclusions

Vascular deficiencies beyond arterial caliber persist in individuals with WBS who have undergone PA stenosis intervention. Evaluation of Eln^+/− mice reveals complex vascular changes that affect the proximal and distal vasculatures. Minoxidil, given post-weaning, decreases RVSP and improves lumen diameter, but does not alter other earlier-onset vascular patterns. Our data suggest additional therapies including minoxidil could be a useful adjunct to surgical therapy, and future trials should be considered.

Single-atom logic for heterocycle editing

Medicinal chemistry continues to be impacted by new synthetic methods. Particularly sought after, especially at the drug discovery stage, is the ability to enact the desired chemical transformations in a concise and chemospecific fashion. To this end, the field of organic synthesis has become captivated by the idea of 'molecular editing'-to rapidly build onto, change or prune molecules one atom at a time using transformations that are mild and selective enough to be employed at the late stages of a synthetic sequence. In this Review, the definition and categorization of a particularly promising subclass of molecular editing reactions, termed 'single-atom skeletal editing', are proposed. Although skeletal editing applies to both cyclic and acyclic compounds, this Review focuses on heterocycles, both for their centrality in medicinal chemistry and for the definitional clarity afforded by a focus on ring systems. A classification system is presented by highlighting methods (both historically important examples and recent advances) that achieve such transformations, with the goal to spark interest and inspire further development in this growing field.

Scaffold hopping by net photochemical carbon deletion of azaarenes

Discovery chemists routinely identify purpose-tailored molecules through an iterative structural optimization approach, but the preparation of each successive candidate in a compound series can rarely be conducted in a manner matching their thought process. This is because many of the necessary chemical transformations required to modify compound cores in a straightforward fashion are not applicable in complex contexts. We report a method that addresses one facet of this problem by allowing chemists to hop directly between chemically distinct heteroaromatic scaffolds. Specifically, we show that selective photolysis of quinoline N-oxides with 390-nanometer light followed by acid-promoted rearrangement affords N-acylindoles while showing broad compatibility with medicinally relevant functionality. Applications to late-stage skeletal modification of compounds of pharmaceutical interest and more complex transformations involving serial single-atom changes are demonstrated.

Direct Deamination of Primary Amines via Isodiazene Intermediates

We report here a reaction that selectively deaminates primary amines and anilines under mild conditions and with remarkable functional group tolerance including a range of pharmaceutical compounds, amino acids, amino sugars, and natural products. An anomeric amide reagent is uniquely capable of facilitating the reaction through the intermediacy of an unprecedented monosubstituted isodiazene intermediate. In addition to dramatically simplifying deamination compared to existing protocols, our approach enables strategic applications of iminium and amine-directed chemistries as traceless methods. Mechanistic and computational studies support the intermedicacy of a primary isodiazene which exhibits an unexpected divergence from previously studied secondary isodiazenes, leading to cage-escaping, free radical species that engage in a chain, hydrogen-atom transfer process involving aliphatic and diazenyl radical intermediates.

Carbon Atom Insertion into Pyrroles and Indoles Promoted by Chlorodiazirines

Herein, we report a reaction that selectively generates 3-arylpyridine and quinoline motifs by inserting aryl carbynyl cation equivalents into pyrrole and indole cores, respectively. By employing α-chlorodiazirines as thermal precursors to the corresponding chlorocarbenes, the traditional haloform-based protocol central to the parent Ciamician-Dennstedt rearrangement can be modified to directly afford 3-(hetero)arylpyridines and quinolines. Chlorodiazirines are conveniently prepared in a single step by oxidation of commercially available amidinium salts. Selectivity as a function of pyrrole substitution pattern was examined, and a predictive model based on steric effects is put forward, with DFT calculations supporting a selectivity-determining cyclopropanation step. Computations surprisingly indicate that the stereochemistry of cyclopropanation is of little consequence to the subsequent electrocyclic ring opening that forges the pyridine core, due to a compensatory homoaromatic stabilization that counterbalances orbital-controlled torquoselectivity effects. The utility of this skeletal transform is further demonstrated through the preparation of quinolinophanes and the skeletal editing of pharmaceutically relevant pyrroles.

Skeletal editing through direct nitrogen deletion of secondary amines

Synthetic chemistry aims to build up molecular complexity from simple feedstocks¹. However, the ability to exert precise changes that manipulate the connectivity of the molecular skeleton itself remains limited, despite possessing substantial potential to expand the accessible chemical space^2,3. Here we report a reaction that 'deletes' nitrogen from organic molecules. We show that N-pivaloyloxy-N-alkoxyamides, a subclass of anomeric amides, promote the intermolecular activation of secondary aliphatic amines to yield intramolecular carbon-carbon coupling products. Mechanistic experiments indicate that the reactions proceed via isodiazene intermediates that extrude the nitrogen atom as dinitrogen, producing short-lived diradicals that rapidly couple to form the new carbon-carbon bond. The reaction shows broad functional-group tolerance, which enables the translation of routine amine synthesis protocols into a strategy for carbon-carbon bond constructions and ring syntheses. This is highlighted by the use of this reaction in the syntheses and skeletal editing of bioactive compounds.

Impaired angiogenesis and extracellular matrix metabolism in autosomal-dominant hyper-IgE syndrome

There are more than 7000 described rare diseases, most lacking specific treatment. Autosomal-dominant hyper-IgE syndrome (AD-HIES, also known as Job's syndrome) is caused by mutations in STAT3. These patients present with immunodeficiency accompanied by severe nonimmunological features, including skeletal, connective tissue, and vascular abnormalities, poor postinfection lung healing, and subsequent pulmonary failure. No specific therapies are available for these abnormalities. Here, we investigated underlying mechanisms in order to identify therapeutic targets. Histological analysis of skin wounds demonstrated delayed granulation tissue formation and vascularization during skin-wound healing in AD-HIES patients. Global gene expression analysis in AD-HIES patient skin fibroblasts identified deficiencies in a STAT3-controlled transcriptional network regulating extracellular matrix (ECM) remodeling and angiogenesis, with hypoxia-inducible factor 1α (HIF-1α) being a major contributor. Consistent with this, histological analysis of skin wounds and coronary arteries from AD-HIES patients showed decreased HIF-1α expression and revealed abnormal organization of the ECM and altered formation of the coronary vasa vasorum. Disease modeling using cell culture and mouse models of angiogenesis and wound healing confirmed these predicted deficiencies and demonstrated therapeutic benefit of HIF-1α-stabilizing drugs. The study provides mechanistic insights into AD-HIES pathophysiology and suggests potential treatment options for this rare disease.

Exfoliation of boron carbide into ultrathin nanosheets

Liquid phase exfoliation (LPE) is a method that can be used to produce bulk quantities of two-dimensional (2D) nanosheets from layered van der Waals (vdW) materials. In recent years, LPE has been applied to several non-vdW materials with anisotropic bonding to produce nanosheets and platelets, but it has not been demonstrated for materials with strong isotropic bonding. In this paper, we demonstrate the exfoliation of boron carbide (B4C), the third hardest known material, into ultrathin nanosheets. B4C has a structure consisting of strongly bonded boron icosahedra and carbon chains, but does not have anisotropic cleavage energies to suggest that it can be readily cleaved into nanosheets. B4C has been widely studied for its very high melting point, high mechanical strength, and chemical stability, as well as its zero- and one-dimensional nanostructured forms. Herein, ultrathin nanosheets are successfully prepared by sonication of B4C powder in organic solvents and are characterized by microscopy and spectroscopy. Density functional theory (DFT) simulations reveal that B4C can be cleaved along several different crystallographic planes with similar energetic favourability, facilititated by an unexpected mechanism of breaking boron icosahedra and forming new boron-rich cage structures at the surface. Atomic force microscopy (AFM) shows that the nanosheets produced by LPE are as thin as 5 nm, with an average thickness of 31.4 nm and average area of 16 000 nm2. Raman spectroscopy shows that many of the nanosheets exhibit additional carbon-rich peaks that change with laser irradiation, which are attributed to atomic rearrangements and amorphization at the nanosheet surfaces, consistent with the diverse cleavage planes. High-resolution transmission electron microscopy (HRTEM) demonstrates that many different cleavage planes exist among the exfoliated nanosheets, in agreement with DFT simulations. This work elucidates the exfoliation mechanism of 2D B4C and suggests that LPE can be applied to generate nanosheets from a variety of non-layered and non-vdW materials.

Reframing primary alkyl amines as aliphatic building blocks

While primary aliphatic amines are ubiquitous in natural products, they are traditionally considered inert to substitution chemistry. This review highlights historical and recent advances in the field of aliphatic deamination chemistry which demonstrate these moieties can be harnessed as valuable C(sp3) synthons. Cross-coupling and photocatalyzed transformations proceeding through polar and radical mechanisms are compared with oxidative deamination and other transition metal catalyzed reactions.

Catalytic Enantioselective Synthesis of Difluorinated Alkyl Bromides

We report an iodoarene-catalyzed enantioselective synthesis of β,β-difluoroalkyl bromide building blocks. The transformation involves an oxidative rearrangement of α-bromostyrenes, utilizing HF-pyridine as the fluoride source and m-CPBA as the stoichiometric oxidant. A catalyst decomposition pathway was identified, which, in tandem with catalyst structure-activity relationship studies, facilitated the development of an improved catalyst providing higher enantioselectivity with lower catalyst loadings. The versatility of the difluoroalkyl bromide products was demonstrated via highly enantiospecific substitution reactions with suitably reactive nucleophiles. The origins of enantioselectivity were investigated using computed interaction energies of simplified catalyst and substrate structures, providing evidence for both CH-π and π-π transition state interactions as critical features.

Vascular Casting of Adult and Early Postnatal Mouse Lungs for Micro-CT Imaging

Blood vessels form intricate networks in 3-dimensional space. Consequently, it is difficult to visually appreciate how vascular networks interact and behave by observing the surface of a tissue. This method provides a means to visualize the complex 3-dimensional vascular architecture of the lung. To accomplish this, a catheter is inserted into the pulmonary artery and the vasculature is simultaneously flushed of blood and chemically dilated to limit resistance. Lungs are then inflated through the trachea at a standard pressure and the polymer compound is infused into the vascular bed at a standard flow rate. Once the entire arterial network is filled and allowed to cure, the lung vasculature may be visualized directly or imaged on a micro-CT (µCT) scanner. When performed successfully, one can appreciate the pulmonary arterial network in mice ranging from early postnatal ages to adults. Additionally, while demonstrated in the pulmonary arterial bed, this method can be applied to any vascular bed with optimized catheter placement and endpoints.

Enantioselective Kinetic Resolution/Desymmetrization of Para-Quinols: A Case Study in Boronic-Acid-Directed Phosphoric Acid Catalysis

A chiral phosphoric acid-catalyzed kinetic resolution and desymmetrization of para-quinols operating via oxa-Michael addition was developed and subsequently subjected to mechanistic study. Good to excellent s-factors/enantioselectivities were obtained over a broad range of substrates. Kinetic studies were performed, and DFT studies favor a hydrogen bonding activation mode. The mechanistic studies provide insights to previously reported chiral anion phase transfer reactions involving chiral phosphate catalysts in combination with boronic acids.

Chronic kidney disease in propionic acidemia

Purpose

Propionic acidemia (PA) is a severe metabolic disorder characterized by multiorgan pathology, including renal disease. The prevalence of chronic kidney disease (CKD) in PA patients and factors associated with CKD in PA are not known.

Methods

Thirty-one subjects diagnosed with PA underwent laboratory and clinical evaluations through a dedicated natural history study at the NIH (ClinicalTrials.gov identifier: NCT02890342).

Results

Cross-sectional analysis of the creatinine-based estimated glomerular filtration rate (eGFR) in subjects with native kidneys revealed an age-dependent decline in renal function (P <0.002). Among adults with PA, 4/8 (50%) had eGFR <60 mL/min/1.73 m². There was a significant discrepancy between eGFRs calculated using estimating equations based on serum creatinine compared to serum cystatin C (P <0.0001). The tubular injury marker, plasma lipocalin-2, and plasma uric acid were strongly associated with CKD (P <0.0001). The measured 24-hour creatinine excretion was below normal, even after adjusting for age, height, and sex.

Conclusions

CKD is common in adults with PA and is associated with age. The poor predictive performance of standard eGFR estimating equations, likely due to reduced creatine synthesis in kidney and liver, could delay the recognition of CKD and management of ensuing complications in this population.

Conditional ablation and conditional rescue models for Casq2 elucidate the role of development and of cell-type specific expression of Casq2 in the CPVT2 phenotype

Cardiac calsequestrin (Casq2) associates with the ryanodine receptor 2 channel in the junctional sarcoplasmic reticulum to regulate Ca2+ release into the cytoplasm. Patients carrying mutations in CASQ2 display low resting heart rates under basal conditions and stress-induced polymorphic ventricular tachycardia (CPVT). In this study, we generate and characterize novel conditional deletion and conditional rescue mouse models to test the influence of developmental programs on the heart rate and CPVT phenotypes. We also compare the requirements for Casq2 function in the cardiac conduction system (CCS) and in working cardiomyocytes. Our study shows that the CPVT phenotype is dependent upon concurrent loss of Casq2 function in both the CCS and in working cardiomyocytes. Accordingly, restoration of Casq2 in only the CCS prevents CPVT. In addition, occurrence of CPVT is independent of the developmental history of Casq2-deficiency. In contrast, resting heart rate depends upon Casq2 gene activity only in the CCS and upon developmental history. Finally, our data support a model where low basal heart rate is a significant risk factor for CPVT.

Nonreentrant atrial tachycardia occurs independently of hypertrophic cardiomyopathy in RASopathy patients

Multifocal atrial tachycardia (MAT) has a well-known association with Costello syndrome, but is rarely described with related RAS/MAPK pathway disorders (RASopathies). We report 11 patients with RASopathies (Costello, Noonan, and Noonan syndrome with multiple lentigines [formerly LEOPARD syndrome]) and nonreentrant atrial tachycardias (MAT and ectopic atrial tachycardia) demonstrating overlap in cardiac arrhythmia phenotype. Similar overlap is seen in RASopathies with respect to skeletal, musculoskeletal and cutaneous abnormalities, dysmorphic facial features, and neurodevelopmental deficits. Nonreentrant atrial tachycardias may cause cardiac compromise if sinus rhythm is not restored expeditiously. Typical first-line supraventricular tachycardia anti-arrhythmics (propranolol and digoxin) were generally not effective in restoring or maintaining sinus rhythm in this cohort, while flecainide or amiodarone alone or in concert with propranolol were effective anti-arrhythmic agents for acute and chronic use. Atrial tachycardia resolved in all patients. However, a 4-month-old boy from the cohort was found asystolic (with concurrent cellulitis) and a second patient underwent cardiac transplant for heart failure complicated by recalcitrant atrial arrhythmia. While propranolol alone frequently failed to convert or maintain sinus rhythm, fleccainide or amiodarone, occasionally in combination with propranolol, was effective for RASopathy patient treatment for nonreentrant atrial arrhythmia. Our analysis shows that RASopathy patients may have nonreentrant atrial tachycardia with and without associated cardiac hypertrophy. While nonreentrant arrhythmia has been traditionally associated with Costello syndrome, this work provides an expanded view of RASopathy cardiac arrhythmia phenotype as we demonstrate mutant proteins throughout this signaling pathway can also give rise to ectopic and/or MAT.

A catalytic fluoride-rebound mechanism for C(sp3)-CF3 bond formation

The biological properties of trifluoromethyl compounds have led to their ubiquity in pharmaceuticals, yet their chemical properties have made their preparation a substantial challenge, necessitating innovative chemical solutions. We report the serendipitous discovery of a borane-catalyzed formal C(sp³)-CF₃ reductive elimination from Au(III) that accesses these compounds by a distinct mechanism proceeding via fluoride abstraction, migratory insertion, and C-F reductive elimination to achieve a net C-C bond construction. The parent bis(trifluoromethyl)Au(III) complexes tolerate a surprising breadth of synthetic protocols, enabling the synthesis of complex organic derivatives without cleavage of the Au-C bond. This feature, combined with the "fluoride-rebound" mechanism, was translated into a protocol for the synthesis of ¹⁸F-radiolabeled aliphatic CF₃-containing compounds, enabling the preparation of potential tracers for use in positron emission tomography.

Microbiological outcomes and antibiotic overuse in Emergency Department patients with suspected sepsis

OBJECTIVE

To study the presence of bacterial disease and antibiotic use in patients in the emergency department (ED) included in the local sepsis protocol.

METHODS

An observational retrospective cohort study. Adults aged > 18 years, presenting to the ED of a large teaching hospital, from 1 January to 1 June 2011, with more than two SIRS criteria and a clinical suspicion of sepsis were included.

RESULTS

Bacterial disease was suspected or confirmed in only 71% of all the patients with suspected sepsis (2008 definition) and consequently treated with antibiotics. Most of these patients (58%) suffered from systemic inflammatory response syndrome (SIRS) without signs of organ dysfunction, hypotension or hypoperfusion. Despite absence of bacterial disease in 29% of the patients after rigorous diagnostics, median antibiotic treatment in this group was still seven days (IQR 4-10).

CONCLUSIONS

Standard sepsis detection using SIRS criteria and clinical suspicion identified patients with suspected or confirmed bacterial disease in 71% of the cases. A significant proportion of patients were exposed to prolonged antibiotic use without proof of bacterial disease. This study illustrates the difficulties in correctly identifying bacterial disease and sepsis, and shows that overuse of antibiotics may be the consequence.

GLI1+ progenitor cells in the adrenal capsule of the adult mouse give rise to heterotopic gonadal-like tissue

As certain strains of mice age, hyperplastic lesions resembling gonadal tissue accumulate beneath the adrenal capsule. Gonadectomy (GDX) accelerates this heterotopic differentiation, resulting in the formation of wedge-shaped adrenocortical neoplasms that produce sex steroids. Stem/progenitor cells that reside in the adrenal capsule and retain properties of the adrenogonadal primordium are thought to be the source of this heterotopic tissue. Here, we demonstrate that GLI1⁺ progenitors in the adrenal capsule give rise to gonadal-like cells that accumulate in the subcapsular region. A tamoxifen-inducible Cre driver (Gli1-creER^T2) and two reporters (R26R-lacZ, R26R-confetti) were used to track the fate of GLI1⁺ cells in the adrenal glands of B6D2F2 mice, a strain that develops both GDX-induced adrenocortical neoplasms and age-dependent subcapsular cell hyperplasia. In gonadectomized B6D2F2 mice GLI1⁺ progenitors contributed to long-lived adrenal capsule cells and to adrenocortical neoplasms that expressed Gata4 and Foxl2, two prototypical gonadal markers. Pdgfra, a gene expressed in adrenocortical stromal cells, was upregulated in the GDX-induced neoplasms. In aged non-gonadectomized B6D2F2 mice GLI1⁺ progenitors gave rise to patches of subcapsular cell hyperplasia. Treatment with GANT61, a small-molecule GLI antagonist, attenuated the upregulation of gonadal-like markers (Gata4, Amhr2, Foxl2) in response to GDX. These findings support the premise that GLI1⁺ progenitor cells in the adrenal capsule of the adult mouse give rise to heterotopic tissue.

Hypercalcemia in Patients with Williams-Beuren Syndrome

OBJECTIVE

To evaluate the timing, trajectory, and implications of hypercalcemia in Williams-Beuren syndrome (WBS) through a multicenter retrospective study.

STUDY DESIGN

Data on plasma calcium levels from 232 subjects with WBS aged 0-67.1 years were compared with that in controls and also with available normative data. Association testing was used to identify relevant comorbidities.

RESULTS

On average, individuals with WBS had higher plasma calcium levels than controls, but 86.7% of values were normal. Nonpediatric laboratories overreport hypercalcemia in small children. When pediatric reference intervals were applied, the occurrence of hypercalcemia dropped by 51% in infants and by 38% in toddlers. Across all ages, 6.1% of the subjects had actionable hypercalcemia. In children, actionable hypercalcemia was seen in those aged 5-25 months. In older individuals, actionable hypercalcemia was often secondary to another disease process. Evidence of dehydration, hypercalciuria, and nephrocalcinosis were common in both groups. Future hypercalcemia could not be reliably predicted by screening calcium levels. A subgroup analysis of 91 subjects found no associations between hypercalcemia and cardiovascular disease, gastrointestinal complaints, or renal anomalies. Analyses of electrogradiography data showed an inverse correlation of calcium concentration with corrected QT interval, but no acute life-threatening events were reported.

CONCLUSIONS

Actionable hypercalcemia in patients with WBS occurs infrequently. Although irritability and lethargy were commonly reported, no mortality or acute life-threatening events were associated with hypercalcemia and the only statistically associated morbidities were dehydration, hypercalciuria, and nephrocalcinosis.

[Sphincter Ochsner dyskinesia as a cause of superior mesenteric artery syndrome]

OBJECTIVE

to investigate the pathological physiology of superior mesenteric artery syndrome (SMAS).

MATERIAL AND METHODS

We selected 35 articles devoted to SMAS, which were published from 1990 to 2014, and performed radiometric analysis of X-rays, CT scans and MRI slices found in these articles. In pictures the narrowing in the third part of the duodenum was measured from the boundary of the expanded segment to the level of the superior mesenteric artery (SMA).

RESULTS

Only in 6 (17%) of 35 cases the narrowing portion of duodenum was located directly between aorta and SMA, and its length was about 1 cm. In the remaining 29 cases, the beginning of the narrow segment was 2.5-4.6 cm (average 3.30 ± 0.15 cm) proximal to SMA, ie, most of the narrowed duodenum was out of aortomesenteric angle. Location and length of the narrowed segment of duodenum corresponded to the location and length (3.2 ± 0.15 cm) (P > 0.2) of the functional Ochsner sphincter.

CONCLUSION

These data indicate that in most cases of SMAS the sphincter Oclisner dyskinesia causes the disease. It is likely that the disease is triggered by heavy stressful conditions that cause a sharp and sustained reduction in the pH of gastric secretions, which in turn leads to the spasms of the sphincter Ochsner. With time this condition progresses to hypertrophy of the contracted wall of the duodenum with subsequent replacement of the muscle fibers by connective tissue. This can lead to the rigidity of the wall.

Scope and Mechanism of Cooperativity at the Intersection of Organometallic and Supramolecular Catalysis

The scope and mechanism of the microenvironment-catalyzed C(sp(3))-C(sp(3)) reductive elimination from transition metal complexes [Au(III), Pt(IV)] is explored. Experiments detailing the effect of structural perturbation of neutral and anionic spectator ligands, reactive alkyl ligands, solvent, and catalyst structure are disclosed. Indirect evidence for a coordinatively unsaturated encapsulated cationic intermediate is garnered via observation of several inactive donor-arrested inclusion complexes, including a crystallographically characterized encapsulated Au(III) cation. Finally, based on stoichiometric experiments under catalytically relevant conditions, a detailed mechanism is outlined for the dual supramolecular and platinum-catalyzed C-C coupling between methyl iodide and tetramethyltin. Determination of major platinum species present under catalytic conditions and subsequent investigation of their chemistry reveals an unexpected interplay between cis-trans isomerism and the supramolecular catalyst in a Pt(II)/Pt(IV) cycle, as well as several off-cycle reactions.

PATHOGENETIC SIGNIFICANCE OF DYSKINESIA OF THE SPHINCTER OF OKSNER IN THE DEVELOPMENT OF THE SYNDROME OF THE SUPERIOR MESENTERIC ARTERY

The goal of this study is to investigate the pathological physiology of superior mesenteric artery syndrome (SMAS).

MATERIALS AND METHODS

We selected 35 articles devoted to SMAS, which were published from 1990 to 2014, and performed radiometric analysis of X-rays, CT scans and MRI slices found in these articles. In pictures the narrowing in the third part of the duodenum was measured from the boundary of the expanded segment to the level of the superior mesenteric artery (SMA).

RESULTS

Only in 6 (17%) of. 35 cases the narrowing portion of duodenum was located directly between aorta and SMA, and its length was about 1cm. In the remaining 29 cases, the beginning of the narrow segment was 2.5-4.6 cm (average 3.30 ±0.15 cm) proximal to SMA, ie, most of the narrowed duodenum was out of aortomesenteric angle. Location and length of the narrowed segment of duodenum corresponded to the location and length (3.2 ± 0.15 cm) (P> 0.2) of the functional Ochsner sphincter.

CONCLUSION

These data indicate that in most cases of SMAS the sphincter Ochsner dyskinesia causes the disease. It is likely that the disease is triggered by heavy stressful conditions that cause a sharp and sustained reduction in the pH of gastric secretions, which in turn leads to the spasms of the sphincter Ochsner. With time this condition progresses to hypertrophy of the contracted wall of the duodenum with subsequent replacement of the muscle fibers by connective tissue. This can lead to the rigidity of the wall.

Photoredox Catalysis Unlocks Single-Electron Elementary Steps in Transition Metal Catalyzed Cross-Coupling

Since initial reports, cross-coupling technologies employing photoredox catalysts to access novel reactivity have developed with increasing pace. In this Outlook, prominent examples from the recent literature are organized on the basis of the elementary transformation enabled by photoredox catalysis and are discussed in the context of relevant historical precedent in stoichiometric organometallic chemistry. This treatment allows mechanistic similarities inherent to odd-electron transition metal reactivity to be generalized to a set of lessons for future reaction development.

[Duodenal motility in norm and in some diseases. Hypothesis]

AIM

to investigate the duodenal motility on the basis of radiological studies.

PATIENTS AND METHODS

We tested our hypothesis that sphincters of Kapandji and Ochsner are contracted in response to stimulation of duodenum by hydrochloric acid. These sphincters are not found in standard X-ray studies because barium does not contain hydrochloric acid when it coming from the stomach into the duodenum. The retrospective analysis of radiological studies of the upper digestive tract of 116 patients aged 55 to 92 years was done. The first group consisted of 83 patients in whom the study was conducted using conventional barium suspension. The second group consisted of 8 patients who received 200 ml of barium with the addition of 3 grams of vitamin C. The third group was comprised of 25 patients with primary duodenal diverticula. The fourth group included radiographs from 35 articles devoted to the superior mesenteric artery syndrome (SMAS). We measured the width of the duodenum and the length of the sphincters on these radiographs.

RESULTS AND CONCLUSION

We found an important role of the sphincters (bulbo-duodenal, Kapandji, Ochsner) in the duodenal physiology. On this basis, we proposed the hypothesis defining basic patterns of the duodenal motor function. Proposed hypothesis allows us to understand how the duodenum performs important functions and provides new avenues for understanding the pathogenesis of acquired diseases of the upper gastrointestinal tract. The different forms dyskinesia of these sphincters play an important role in the pathogenesis of the SMAS, primary duodenal diverticula and sphincter Oddi dyskinesia.

GASTRIC MOTILITY HYPOTESIS

The publication is based on a retrospective analysis of 344 radiological studies of the upper digestive tract and analysis of the literature. We propose the hypothesis of the gastric motility, based on the following points: 1) The gastric cardia is the intra-abdominal portion of the lower esophageal sphincter (LES). Its tone increases in response to the increasing pressure in the stomach. 2) in gastroesophageal reflux disease (GERD), the cardia cannot withstand the pressure and subsequently opens. Depending on the degree of insufficiency of the LES and the force applied during provocative test, angular deformity of the stomach appears, due to the shortening of LES as well as a downsizing of the gas bubble in the stomach; 3) Pyloric sphincter (PS) is a true sphincter. Evacuation from the stomach is the result of the opening of the PS due to increase of antral pressure above the "threshold" level; 4) The evacuation starts in the upright position, when the liquid chyme above PS creates hydrostatic pressure above the threshold; 5) When hydrostatic pressure is reduced below the threshold level or in the recumbent position the antral pressure is created by the clamping of deep peristaltic wave and formation of the closed antral cavity; 6) The portioned evacuation is provided in two ways; a) the volume of antral cavity corresponds to the volume of duodenal bulb; b) in upright position after filling of the duodenal bulb the postbulbar sphincter is closed, whereby the pressure in the bulb rises, which leads to a reflex contraction of the PS and cessation of the e stomach emptying.

THE PATHOGENESIS OF ACUTE APPENDICITIS. THE NON-SPECIFIC RESPONSE OF THE DIGESTIVE TRACT IN ACUTE INFLAMMATION IN THE ABDOMEN

Based on the analysis of literature and our own studies we propose hypothesis of the pathogenesis of acute appendicitis (AA), which differs from the following generally accepted provisions. Acute appendidtis develops as a result of immunological reaction and hyperplasia of the mucous membrane of the appendix. Frequency peaks related to age, sex, and seasonal changes of AA are due to increased excretion of sex hormones. Only a small percentage of cases of primary hyperplasia causes a complete occlusion of the lumen and destructive AA. Usually it is exposed to regression without causing the typical symptoms, but leaving the damaged nervous system and / or sclerotic changes that violate the peristalsis of the appendix. Faeces, lingering in appendix eventually harden, increasing in size and often get saturated with salts. In the next fit of hyperplasia, the walls are stretched over fecolithe, causing obstruction of the lumen, the formation of a closed cavity and the known mechanisms of inflammation. Inflammation leads to increased tone of the stomach and colon, but strong in the segments of intestine lay next to the A. This is accompanied by increased of the anal canal pressure. Increased tone of the digestive tract is a nonspecific response to acute inflammation. We can assume that the same reaction is observed at any localization of acute and chronic inflammation.

A supramolecular microenvironment strategy for transition metal catalysis

A self-assembled supramolecular complex is reported to catalyze alkyl-alkyl reductive elimination from high-valent transition metal complexes [such as gold(III) and platinum(IV)], the central bond-forming elementary step in many catalytic processes. The catalytic microenvironment of the supramolecular assembly acts as a functional enzyme mimic, applying the concepts of enzymatic catalysis to a reactivity manifold not represented in biology. Kinetic experiments delineate a Michaelis-Menten-type mechanism, with measured rate accelerations (k(cat)/k(uncat)) up to 1.9 × 10(7) (here k(cat) and k(uncat) are the Michaelis-Menten enzymatic rate constant and observed uncatalyzed rate constant, respectively). This modality has further been incorporated into a dual catalytic cross-coupling reaction, which requires both the supramolecular microenvironment catalyst and the transition metal catalyst operating in concert to achieve efficient turnover.

Electrophysiologic consequences of KATP gain of function in the heart: Conduction abnormalities in Cantu syndrome

BACKGROUND

Gain-of-function (GOF) mutations in the KATP channel subunits Kir6.1 and SUR2 cause Cantu syndrome (CS), a disease characterized by multiple cardiovascular abnormalities.

OBJECTIVE

The purpose of this study was to better determine the electrophysiologic consequences of such GOF mutations in the heart.

METHODS

We generated transgenic mice (Kir6.1-GOF) expressing ATP-insensitive Kir6.1[G343D] subunits under α-myosin heavy chain (α-MHC) promoter control, to target gene expression specifically in cardiomyocytes, and performed patch-clamp experiments on isolated ventricular myocytes and invasive electrophysiology on anesthetized mice.

RESULTS

In Kir6.1-GOF ventricular myocytes, KATP channels showed decreased ATP sensitivity but no significant change in current density. Ambulatory ECG recordings on Kir6.1-GOF mice revealed AV nodal conduction abnormalities and junctional rhythm. Invasive electrophysiologic analyses revealed slowing of conduction and conduction failure through the AV node but no increase in susceptibility to atrial or ventricular ectopic activity. Surface ECGs recorded from CS patients also demonstrated first-degree AV block and fascicular block.

CONCLUSION

The primary electrophysiologic consequence of cardiac KATP GOF is on the conduction system, particularly the AV node, resulting in conduction abnormalities in CS patients who carry KATP GOF mutations.

[Descending perineum syndrome in children: Pathophysiology and diagnosis]

OBJECTIVE

To propose a safer, simpler, and more exact method for the diagnosis of descending perineum syndrome (DPS).

MATERIAL AND METHODS

A total of 194 patients aged 5 days to 15 years were examined and divided into 2 groups: Group 1 consisted of 65 patients without anorectal anomalies (AA); Group 2 comprised 129 patients, including 66 children with functional constipation, 55 with AA and visible fistulas, who were preoperatively examined, and 8 patients with anorectal angle (ARA), who were postoperatively examined. All the patients underwent irrigoscopy that was different from standard examination in the presence of X-ray CT contrast marker near the anus.

RESULTS AND CONCLUSION

DPS is caused by puborectalis muscle dysfunction. A method was proposed to evaluate the status of the puborectalis muscle from the distance between the position of the ARA and the marker near the anus. This not only promotes an exacter estimate of DPS, but also allows refusal of defecography. The use of a barium enema with the minimum number of X-ray films decreases dose of ionizing radiation hazard and permits the use of this procedure not only in adults, but also in children with chronic constipation, fecal incontinence, and in AA for both pre- and postoperatively assessment of the causes of complications.

[Schatzki ring as a symptom of gastroesophageal reflux disease]

OBJECTIVE

To determine the importance of a symptom of Schatzki ring.

MATERIAL AND METHODS

The results of examining 95 patients aged 62-92 years with the symptoms of dyspepsia in the Netanya State Geriatric Center (Israel) in 1994-2004 were analyzed. Standard X-ray study of the upper digestive tract was complemented by provocation tests. The length of an X-ray-negative area (XNA) between barium in the esophagus and stomach and the width in the lower esophagus were measured.

RESULTS

Only 2 (2%) of the 95 patients were found to have normal function of the gastroesophageal junction (GEJ). Two patients with a drastic esophageal narrowing due to reflux esophagitis were excluded. The remaining (91) patients were divided into 2 groups. The width of the esophagus was less than 2 cm and 2 cm or more in 64 (70%) and 27 (30%) patients, respectively. In weak GEJ, there was esophageal dilatation above the XNA. When in a horizontal position, this portion of the esophagus evacuates its contents into the stomach as a result of ampullary function. It is proximally closed by contracting the functional proximal sphincter (PS). When the ampulla contracts, its pressure increases up to the threshold. This causes the XNA to be closed and the ampulla to inject its contents into the stomach. The wider was the ampulla, the shorter the XNA was. Schatzki ring was detected in 20 (22%) of the 91 patients with gastroesophageal reflux disease (GERD). It was always at the level of the PS.

CONCLUSION

The so-called sliding esophageal hernia is an esophageal ampulla measuring more than 2 cm in wide. The presence of the esophageal ampulla despite its size suggests that the GEJ is incompetent and GERD is present. Schatzki ring occurs at the level of the PS due to reflux esophagitis.

Isolating primary melanocyte-like cells from the mouse heart

We identified a novel population of melanocyte-like cells (also known as cardiac melanocytes) in the hearts of mice and humans that contribute to atrial arrhythmia triggers in mice. To investigate the electrical and biological properties of cardiac melanocytes we developed a procedure to isolate them from mouse hearts that we derived from those designed to isolate neonatal murine cardiomyocytes. In order to obtain healthier cardiac melanocytes suitable for more extensive patch clamp or biochemical studies, we developed a refined procedure for isolating and plating cardiac melanocytes based on those originally designed to isolate cutaneous melanocytes. The refined procedure is demonstrated in this review and produces larger numbers of healthy melanocyte-like cells that can be plated as a pure population or with cardiomyocytes.

Gold-catalyzed allylation of aryl boronic acids: accessing cross-coupling reactivity with gold

A sp(3)-sp(2) C-C cross-coupling reaction catalyzed by gold in the absence of a sacrificial oxidant is described. Vital to the success of this method is the implementation of a bimetallic catalyst bearing a bis(phosphino)amine ligand. A mechanistic hypothesis is presented, and observable transmetalation, C-Br oxidative addition, and C-C reductive elimination in a model gold complex are shown. We expect that this method will serve as a platform for the development of novel transformations involving redox-active gold catalysts.

[The pathological physiology of the anorectal defects, from the new concept to the new treatment]

PURPOSE

To determine physiology of anorectal zone in norm and anorectal malformations (ARM) to optimize the surgical treatment.

MATERIAL AND METHODS

Examination of 119 patients were selected, including 65 children without anorectal pathology and 54 patients with ARM. We performed barium enema with radiopaque marker placed near the anus. The manometric study of anorectal area was done using intubation tube with an inflatable cuff.

RESULTS

The anal canal was detected in all of ARM patients with perineal and vestibular fistulas, as well as in most of the newborns without fistula. The well innervated internal anal sphincter (IAS) was located in the loop of the puborectal muscle (PRM) and connected to the levator ani muscle (LAM) which opens the anal canal during defecation. Anterior and posterior sagittal approaches use IAS excision, with PRM damage and cutting off the LAM from IAS, which leads to incontinence and/or chronic constipation.

CONCLUSION

We describe two surgical approaches that allow preservation of all elements of the anal canal resulting in a normal post-operative continence and defecation.

[Pathological physiology of gastroesophageal reflux disease. Hypothesis (Literature review)]

Currently prolonged pH-monitoring is considered as Gold standard for diagnosis of Gastro Esophageal Reflux Disease (GERD). Criteria and norms based on prolonged pH-monitoring were the basic concepts of pathophysiology of GERD. For example, it is accepted that esophageal hernia (EG) can be present without GERD, as well as GERD without EG. X-ray diagnosis compared to the pH- monitoring has a low sensitivity (70%) and specificity (74%). Meanwhile, in recent decades, it has been found that the pH-metry is not effective in a non-erosive reflux disease. We figured that the criteria and norms of pH-monitoring are not accurate. The purpose of this study is to determine the radiological norms of gastroesophageal junction (EGJ) and, to clarify the pathological physiology of GERD according to the new criteria and analysis of the literature.

MATERIAL AND METHOD

The analysis of the survey of 452 patients was done. Among them were 263 children aged from 1 day to 15 years who have applied to the Belarusian Center of Pediatric Surgery (BCPS) in 1983-1987 and 189 patients aged 15-92 years surveyed in the BCPC, as well as in the Government Geriatric Center (Israel) in 1994-2004. The standard radiography of the upper digestive tract was supplemented by provocative tests. In 21 children and 36 adults survey was carried out to locate space-occupying lesions of the chest or abdomen. Other patients had symptoms of GERD.

RESULTS

The 21 children and 17 of 34 adult patients without of GERD symptoms had the same radiographic picture, indicating of the normal LES function: the width of the esophagus was the same all over and no more than 1.5 cm; in a horizontal position a peristaltic wave opens the LES and pushes its contents into the stomach without delay, despite the provocative tests. In 15 out of 34 adults with no symptoms of GERD radiographic findings show signs of LES weakness. In these patients, with a mild GERD, abdominal compression caused contraction of the GEJ with length of (3.60 +/- 0.8 cm) in adults which corresponds to the length of the LES, according to the manometric studies. A rounded cavity (phrenic ampoule) is formed above the contracted LES when the functional'proximal sphincter' (PS) is closed cranially. When, during the am ampoule contraction the pressure in it reaches a threshold level, LES is opened, and the ampoule injects its contents into the stomach. Inflammation of the esophageal wall leads to the gradual ampoule expansion. With a width of the ampulla 2 cm and more we found no evidence of the displacement of the stomach into the chest cavity. The radiological symptoms of GERD are described, the identification of which at rest and during provocation, can be used for grading the antireflux function impairment of LES.

CONCLUSION

1. In GERD the last peristaltic wave expands, forming a phrenic ampoule, which is closed cranially by the PS. 2. The width of the ampoule is proportional to the stages of GERD. This means that ampoule as well as the so-called esophageal hernia are symptoms of GERD. 3. During the ampoule formation the inner surface of it increases by at least to 11 cm2. The deficit of the mucosa is compensated by the motion of the mucosa from GEJ. The shortening of the longitudinal muscle during the ampulla contraction does not significantly affect the length of the esophagus. 4. Transient LES relaxation is caused by a deficiency of the LES capacity.

Oxidation-initiated Nazarov cyclization of vinyl alkoxyallenes

A mild method for the diastereoselective formation of C(4), C(5)-disubstituted cyclopentenones has been developed, involving formation of a pentadienyl cation via diastereoselective oxidation of a vinyl alkoxyallene. Conrotatory electrocyclization provides the cyclopentenone product. The broad scope, mild conditions, and uncommon substitution pattern accessible through this transformation make it a useful addition to the existing repertoire of cyclopentenone synthetic methods.