A multidisciplinary approach to laparoscopic sleeve gastrectomy among multiethnic adolescents in the United States.

BACKGROUND: Childhood obesity has become a serious public health problem in our country with a prevalence that is disproportionately higher among minority groups. Laparoscopic sleeve gastrectomy (LSG) is gaining attention as a safe bariatric alternative for severely obese adolescents. STUDY DESIGN: A retrospective study on morbidly obese adolescents that underwent LSG at our institution from 2009 to 2017. Primary outcomes were weight loss as measured by change in BMI and percent excess weight loss (%EWL) at 1 year after surgery, resolution of comorbidities and occurrence of complications. RESULTS: Thirty-eight patients, of whom 71% were female and 74% were ethnic minorities, underwent LSG between 2009 and 2016. Mean age was 16.8years, mean weight was 132.0kg and mean BMI was 46.7. There were no surgical complications. Mean %EWL was 19.4%, 27.9%, 37.4%, 44.9%, and 47.7% at 1.5, 3, 6, 9, and 12month follow up visits, respectively. Comorbidity resolution rates were 100% for hypertension and nonalcoholic fatty liver disease, 91% for diabetes, 44% for prediabetes, 82% for dyslipidemia and 89% for OSA. CONCLUSIONS: LSG is an effective and safe method of treatment of morbid obesity in adolescents as it can significantly decrease excess body weight and resolve comorbid conditions. Further studies are needed to investigate the long-term effects of LSG in adolescents. CLINICAL RESEARCH STUDY: Descriptive case series with prospective database. LEVEL OF EVIDENCE: IV.

In vitro evaluation of Midwest Caries ID: a novel light-emitting diode for caries detection.

INTRODUCTION: Traditional detection techniques have limits in diagnosing occlusal caries. Thus, more accurate methods are needed. This study evaluates the ability of the Midwest Caries ID (Midwest) to detect caries. METHODS: Two hundred sixty-four extracted, nonrestored premolars and molars were cleaned and stored in 0.2% sodium azide. Teeth were divided into three groups of 88. One examination site on each occlusal surface was chosen. Each site was inspected by a calibrated examiner via visual, Midwest, and histologic exams. First, a visual exam was performed following the International Caries Detection and Assessment guidelines. Next, the same site was inspected using the Midwest device. Finally, the tooth was sectioned mesiodistally through the site. The half with greater caries progression was visualized under a stereomicroscope (64×). Histologic appearance was scored based on the Downer system. Data were analyzed using Kendall tau-b, partial correlation coefficients, and the receiver operating characteristics curve. RESULTS: Overall, the Midwest scoring assessment correlated with histologic assessments (tau = 0.32; p<0.0001), but the visual exam had a stronger correlation (tau = 0.53; p<0.0001) with the histologic exam. The sensitivity and specificity of the Midwest was also reported at 0.56 and 0.84, compared with 0.92 and 0.43, respectively, for the visual exam. CONCLUSIONS: Midwest Caries ID is a novel caries detection device that has limitations and should not be used as the sole means to detect occlusal caries.

Vitamin D--deficient rickets in a child with cow's milk allergy.

This article describes the case of a 16-month-old Hispanic male toddler with cow's milk allergy living in northern California who was admitted to a children's hospital for weight loss and markedly elevated levels of serum alkaline phosphatase and parathyroid hormone. At a routine outpatient well-child visit, his mother expressed concern about a decrease in his appetite and activity level. A detailed diet history revealed that breast milk was his primary source of nutrition during his first year of life and he had not been given supplemental vitamins. With attempts to introduce cow's milk formula, he had developed a rash and swelling around the mouth. Shortly after his first birthday, his mother weaned him from breast milk and introduced unfortified rice milk as a palatable milk substitute. Upon admission he was pale and lethargic; his laboratory studies were remarkable for elevated serum alkaline phosphatase and parathyroid hormone and low levels of phosphorus, 25-hydroxy-vitamin D, and ferritin. Lower extremity radiographic studies were consistent with rickets. After 5 weeks of therapy with vitamin D(3) and iron, his serum 25-hydroxy-vitamin D level normalized. Within 12 weeks following therapy, the child demonstrated significant clinical improvement, with resolution of growth failure and bone reossification. His activity level had returned to normal. This case emphasizes the importance of adequate vitamin D intake for children with special attention to those who might have nutrition deficiencies attributable to milk allergy.

High-throughput sample handling and data collection at synchrotrons: embedding the ESRF into the high-throughput gene-to-structure pipeline.

An automatic data-collection system has been implemented and installed on seven insertion-device beamlines and a bending-magnet beamline at the ESRF (European Synchrotron Radiation Facility) as part of the SPINE (Structural Proteomics In Europe) development of an automated structure-determination pipeline. The system allows remote interaction with beamline-control systems and automatic sample mounting, alignment, characterization, data collection and processing. Reports of all actions taken are available for inspection via database modules and web services.

The care and nurture of undulator data sets.

Undulator radiation is the X-ray source of choice for modern macromolecular crystallography beamlines. Here, the basic properties of undulator sources are described and it is indicated why they make such good X-ray sources for macromolecular crystallography. Collection of excellent data from these beamlines is not always straightforward; therefore, a number of rules are postulated for undulator data collection and guidelines are offered which will help to ensure a satisfactory experiment.

Comparison of moments and couple-generating forces near discontinuities in structural-acoustic systems.

In modeling vibration isolators in structural-acoustic systems, the isolator's dynamic properties are often treated as acting only in the axial direction as moments are often neglected. Furthermore, the size, or scale, of the isolator is often neglected and the isolator is assumed to act at single points on the connected structures. Previous work has shown that concentrated moments can be particularly important when located near a fixed support or a structural discontinuity. This research extends that work to examine the importance of moment scale effects for a system containing a distributed structural discontinuity with its own scale. Moment scale effects are examined by determining the difference in radiated acoustic power for a simple system that is excited by a couple-generating distributed force and a concentrated moment. The distributed force produces a couple that is equivalent to the concentrated moment. As a result, only the scale is being examined. Particular interest occurs when the excitation is located near the structural discontinuity. Based on the cases studied here, moment scale is shown to be important at lower frequencies when the excitation is located near the edges of the discontinuity. At higher frequencies, any overlap of the excitation and discontinuity may warrant the need to consider moment scales.

Crystallization of a recombinant form of the complete sequence of human gamma-interferon: characterization by small-angle X-ray scattering, mass spectrometry and preliminary X-ray diffraction studies.

The crystallization conditions of a recombinant form of the complete sequence of human gamma-interferon, designated r-hu IFN-gamma (RU 42369), have been determined after studying the behaviour of this protein in solution by small-angle X-ray scattering (SAXS) as a function of pH and salt type. IFN-gamma is difficult to crystallize without truncating at least the last five amino acids of the C-terminus; the SAXS results suggest viable crystallization conditions that led to crystals of r-hu IFN-gamma suitable for X-ray diffraction analysis. The crystals were grown in the presence of ammonium sulfate using vapour-diffusion techniques. The crystals, which diffract to 5 A resolution at best, belong to the primitive tetragonal space group P42(1)2 and have unit-cell parameters a = b = 123.4, c = 93.4 A. The protein contained in these crystals was analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), which verified the presence of the complete amino-acid sequence of r-hu IFN-gamma.

Structure of cytochrome c7 from Desulfuromonas acetoxidans at 1.9 A resolution.

Multihaem cytochromes play a key role in electron-transport reactions in the periplasm of sulfate- and sulfur-reducing bacteria. The redox proteins grouped in the c3 superfamily also display metal-reducing activities, which make them interesting biotechnological tools. The crystal structure of the fully oxidized cytochrome c7 from Desulfuromonas acetoxidans has been solved by combined molecular-replacement and MAD methods. The structure has been refined at 1.9 A resolution to an R value of 19.1% (R(free) = 24.3%) and includes three haems and 116 water molecules. The protein displays the cytochrome c3 fold in a highly minimized form, while haem 2 and the surrounding protein environment are missing. The geometry of haem packing and of the haem axial ligands and propionates are described and compared with that of c3 cytochromes. The crystal structure is compared with the solution structure recently obtained by NMR methods and with its homologue cytochromes of the c3 superfamily. Comparison of the high number of available structures makes it possible to analyze the structural role of the few highly conserved residues, in addition to the cysteines and histidines that link the porphyrin rings and the Fe atoms to the protein chain.

The influence of substructure modeling on the structural-acoustic response of a plate system.

Changes in the vibro-acoustic response of a fluid-loaded plate due to variations in some of the modeling details associated with an attached substructure are examined. The attached substructure consists of a smaller plate supported by springs along each edge. To examine the important modeling issues, three studies are performed. In the first study, discrete changes in the system response due to discrete changes in the size of the region over which the spring elasticity is distributed are examined. In the second study, substructure modeling issues are examined by varying the number of degrees-of-freedom included in the substructure model. Finally, sensitivity relationships that express changes in the system response to changes in the scale of the spring elements are developed. These relationships are used to examine changes in the system response due to small variations in the scale of the distributed elasticity. Both the combined system response and acoustic radiation are computed using the Acoustic Surface Variational Principle and Hamilton's Principle. For the example cases considered, it is shown that details associated with the scale of the spring are only important for frequencies near or below the resonances of the isolated subsystem. Furthermore, only the dynamics of the substructure including rigid-body type motions are important.

Estimation of structural wave numbers from spatially sparse response measurements.

A method is presented for estimating the complex wave numbers and amplitudes of waves that propagate in damped structures, such as beams, plates, and shells. The analytical basis of the method is a wave field that approximates response measurements in an aperture where no excitations are applied. At each frequency, the method iteratively adjusts wave numbers to best approximate response measurements, using wave numbers at neighboring frequencies as initial estimates in the search. In comparison to existing methods, the method generally requires far fewer measurement locations and does not require evenly spaced locations. The number of locations required by the method scales with the number of waves that propagate in the structure, whereas the number of locations required by existing methods scales with the minimum wavelength. In addition, the method allows convenient inclusion of the analytic relationships between wave numbers that exist for flexural vibrations of beams and plates. Advantages of the method are illustrated by an example in which a beam is excited by a transverse force at one end. Using analytic data and experimental measurements, the method produces a wave field that matches response measurements to within 1 percent. One interesting feature of the new method is that, when applied to analytic data, it supplies more robust wave number estimates using responses at unevenly spaced locations.

Low-resolution phase information in multiple-wavelength anomalous solvent contrast variation experiments.

The basic theory and principles of the multiple-wavelength anomalous solvent-contrast (MASC) method are introduced as a contrast-variation technique for generating low-resolution crystallographic phase information on the envelope of a macromolecule. Experimental techniques and practical considerations concerning the choice of anomalous scatterer, sample preparation and data acquisition are discussed. Test cases of crystals of three proteins of differing molecular weights from 14 kDa through to 173 kDa are illustrated. Methods for extracting the moduli of the anomalous structure factors from the MASC data are briefly discussed and the experimental results are compared with the known macromolecular envelopes. In all cases, the lowest resolution shells exhibit very large anomalous signals which diminish at higher resolution, as expected by theory. However, in each case the anomalous signal persists at high resolution, which is strong evidence for ordered sites of the anomalous scatterers. For the smaller two of these proteins the heavy-atom parameters could be refined for some of these sites. Finally, a novel method for phasing the envelope structure-factor moduli is presented. This method takes into account the relatively low number of observations at low resolution and describes the macromolecular envelope with a small number of parameters by presuming that the envelope is a compact domain of known volume. The parameterized envelope is expressed as a linear combination of independent functions such as spherical harmonics. Phasing starts from solutions of a sphere in the unit cell after positional refinement from random trials and the parameters describing the envelope are then refined against the data of structure-factor moduli. The preliminary results using simulated data show that the method can be used to reconstruct the correct macromolecular envelope and is able to discriminate against some false solutions.

Crystal structure of the S15-rRNA complex.

In bacterial ribosomes, the small (30S) ribosomal subunit is composed of 16S rRNA and 21 distinct proteins. Ribosomal protein S15 is of particular interest because it binds primarily to 16S rRNA and is required for assembly of the small subunit and for intersubunit association, thus representing a key element in the assembly of a whole ribosome. Here we report the 2.8 ¿ resolution crystal structure of the highly conserved S15-rRNA complex. Protein S15 interacts in the minor groove with a G-U/G-C motif and a three-way junction. The latter is constrained by a conserved base triple and stacking interactions, and locked into place by magnesium ions and protein side chains, mainly through interactions with the unique three-dimensional geometry of the backbone. The present structure gives insights into the dual role of S15 in ribosome assembly and translational regulation.

The structure of a Staphylococcus aureus leucocidin component (LukF-PV) reveals the fold of the water-soluble species of a family of transmembrane pore-forming toxins.

BACKGROUND: Leucocidins and gamma-hemolysins are bi-component toxins secreted by Staphylococcus aureus. These toxins activate responses of specific cells and form lethal transmembrane pores. Their leucotoxic and hemolytic activities involve the sequential binding and the synergistic association of a class S and a class F component, which form hetero-oligomeric complexes. The components of each protein class are produced as non-associated, water-soluble proteins that undergo conformational changes and oligomerization after recognition of their cell targets. RESULTS: The crystal structure of the monomeric water-soluble form of the F component of Panton-Valentine leucocidin (LukF-PV) has been solved by the multiwavelength anomalous dispersion (MAD) method and refined at 2.0 A resolution. The core of this three-domain protein is similar to that of alpha-hemolysin, but significant differences occur in regions that may be involved in the mechanism of pore formation. The glycine-rich stem, which undergoes a major rearrangement in this process, forms an additional domain in LukF-PV. The fold of this domain is similar to that of the neurotoxins and cardiotoxins from snake venom. CONCLUSIONS: The structure analysis and a multiple sequence alignment of all toxic components, suggest that LukF-PV represents the fold of any water-soluble secreted protein in this family of transmembrane pore-forming toxins. The comparison of the structures of LukF-PV and alpha-hemolysin provides some insights into the mechanism of transmembrane pore formation for the bi-component toxins, which may diverge from that of the alpha-hemolysin heptamer.

MAD structure of Pseudomonas nautica dimeric cytochrome c552 mimicks the c4 Dihemic cytochrome domain association.

The monohemic cytochrome c552from Pseudomonas nautica (c552-Pn) is thought to be the electron donor to cytochrome cd1, the so-called nitrite reductase (NiR). It shows as high levels of activity and affinity for the P. nautica NiR (NiR-Pn), as the Pseudomonas aeruginosa enzyme (NiR-Pa). Since cytochrome c552is by far the most abundant electron carrier in the periplasm, it is probably involved in numerous other reactions. Its sequence is related to that of the c type cytochromes, but resembles that of the dihemic c4cytochromes even more closely. The three-dimensional structure of P. nautica cytochrome c552has been solved to 2.2 A resolution using the multiple wavelength anomalous dispersion (MAD) technique, taking advantage of the presence of the eight Fe heme ions in the asymmetric unit. Density modification procedures involving 4-fold non-crystallographic averaging yielded a model with an R -factor value of 17.8 % (Rfree=20.8 %). Cytochrome c552forms a tight dimer in the crystal, and the dimer interface area amounts to 19% of the total cytochrome surface area. Four tighly packed dimers form the eight molecules of the asymmetric unit. The c552dimer is superimposable on each domain of the monomeric cytochrome c4from Pseudomomas stutzeri (c4-Ps), a dihemic cytochrome, and on the dihemic c domain of flavocytochrome c of Chromatium vinosum (Fcd-Cv). The interacting residues which form the dimer are both similar in character and position, which is also true for the propionates. The dimer observed in the crystal also exists in solution. It has been hypothesised that the dihemic c4-Ps may have evolved via monohemic cytochrome c gene duplication followed by evolutionary divergence and the adjunction of a connecting linker. In this process, our dimeric c552structure might be said to constitute a "living fossile" occurring in the course of evolution between the formation of the dimer and the gene duplication and fusion. The availability of the structure of the cytochrome c552-Pn and that of NiR from P. aeruginosa made it possible to identify putative surface patches at which the docking of c552to NiR-Pn may occur.

Crystal structure of a double-stranded DNA containing a cisplatin interstrand cross-link at 1.63 A resolution: hydration at the platinated site.

cis-diamminedichloroplatinum (II) (cisplatin) is a powerful anti-tumor drug whose target is cellular DNA. In the reaction between DNA and cisplatin, covalent intrastrand and interstrand cross-links (ICL) are formed. Two solution structures of the ICL have been published recently. In both models the double-helix is bent and unwound but with significantly different angle values. We solved the crystal structure at 100K of a double-stranded DNA decamer containing a single cisplatin ICL, using the anomalous scattering (MAD) of platinum as a unique source of phase information. We found 47 degrees for double-helix bending and 70 degrees for unwinding in agreement with previous electrophoretic assays. The crystals are stabilized by intermolecular contacts involving two cytosines extruded from the double-helix, one of which makes a triplet with a terminal G.C pair. The platinum coordination is nearly square and the platinum residue is embedded into a cage of nine water molecules linked to the cross-linked guanines, to the two amine groups, and to the phosphodiester backbone through other water molecules. This water molecule organization is discussed in relation with the chemical stability of the ICL.

Multiwavelength anomalous solvent contrast (MASC): derivation of envelope structure-factor amplitudes and comparison with model values.

A previous article [Fourme et al. (1995). J. Synchrotron Rad. 2, 36-48] presented the theoretical foundations of MASC, a new contrast-variation method using multiwavelength anomalous scattering, and reported the first experimental results. New experiments have been conducted both at the ESRF (Grenoble, France) and at LURE-DCI (Orsay, France), using cryocooled crystals of three proteins of known structures and very different molecular weights. Amplitudes of {GammaT(h)}, the 'normal' structure factors of the anomalously scattering part of the crystal including the solvent zone and the ordered anomalous scattering sites (if any), have been extracted from multiwavelength data. In the very low resolution range (d >/= 20 A), the agreement between experimental {GammaT(h)} and model values calculated from the bulk solvent is all the more satisfactory since the molecular weight of the protein is high. For spacings between 10 and 20 A, the agreement between experimental {GammaT(h)} and model values is also satisfactory if one takes into account ordered anomalous scatterer sites. Such sites have been found in the three cases.

A zipper-like duplex in DNA: the crystal structure of d(GCGAAAGCT) at 2.1 A resolution.

BACKGROUND: The replication origin of the single-stranded (ss)DNA bacteriophage G4 has been proposed to fold into a hairpin loop containing the sequence GCGAAAGC. This sequence comprises a purine-rich motif (GAAA), which also occurs in conserved repetitive sequences of centromeric DNA. ssDNA analogues of these sequences often show exceptional stability which is associated with hairpin loops or unusual duplexes, and may be important in DNA replication and centromere function. Nuclear magnetic resonance (NMR) studies indicate that the GCGAAAGC sequence forms a hairpin loop in solution, while centromere-like repeats dimerise into unusual duplexes. The factors stabilising these unusual secondary structure elements in ssDNA, however, are poorly understood. RESULTS: The nonamer d(GCGAAAGCT) was crystallised as a bromocytosine derivative in the presence of cobalt hexammine. The crystal structure, solved by the multiple wavelength anomalous dispersion (MAD) method at the bromine K-edge, reveals an unexpected zipper-like motif in the middle of a standard B-DNA duplex. Four central adenines, flanked by two sheared G.A mismatches, are intercalated and stacked on top of each other without any interstrand Watson-Crick base pairing. The cobalt hexammine cation appears to participate only in crystal cohesion. CONCLUSIONS: The GAAA consensus sequence can dimerise into a stable zipper-like duplex as well as forming a hairpin loop. The arrangement closes the minor groove and exposes the intercalated, unpaired, adenines to the solvent and DNA-binding proteins. Such a motif, which can transform into a hairpin, should be considered as a structural option in modelling DNA and as a potential binding site, where it could have a role in DNA replication, nuclease resistance, ssDNA genome packaging and centromere function.