Organic carbon burial in global lakes and reservoirs.

Burial in sediments removes organic carbon (OC) from the short-term biosphere-atmosphere carbon (C) cycle, and therefore prevents greenhouse gas production in natural systems. Although OC burial in lakes and reservoirs is faster than in the ocean, the magnitude of inland water OC burial is not well constrained. Here we generate the first global-scale and regionally resolved estimate of modern OC burial in lakes and reservoirs, deriving from a comprehensive compilation of literature data. We coupled statistical models to inland water area inventories to estimate a yearly OC burial of 0.15 (range, 0.06-0.25) Pg C, of which ~40% is stored in reservoirs. Relatively higher OC burial rates are predicted for warm and dry regions. While we report lower burial than previously estimated, lake and reservoir OC burial corresponded to ~20% of their C emissions, making them an important C sink that is likely to increase with eutrophication and river damming.

A peptide extension dictates IgM assembly.

Professional secretory cells can produce large amounts of high-quality complex molecules, including IgM antibodies. Owing to their multivalency, polymeric IgM antibodies provide an efficient first-line of defense against pathogens. To decipher the mechanisms of IgM assembly, we investigated its biosynthesis in living cells and faithfully reconstituted the underlying processes in vitro. We find that a conserved peptide extension at the C-terminal end of the IgM heavy (Ig-µ) chains, termed the tailpiece, is necessary and sufficient to establish the correct geometry. Alanine scanning revealed that hydrophobic amino acids in the first half of the tailpiece contain essential information for generating the correct topology. Assembly is triggered by the formation of a disulfide bond linking two tailpieces. This induces conformational changes in the tailpiece and the adjacent domain, which drive further polymerization. Thus, the biogenesis of large and topologically challenging IgM complexes is dictated by a local conformational switch in a peptide extension.

Is Hydronephrosis a Complication after Anterior Lumbar Surgery?

Study Design Prospective follow-up design. Objective Ureteral injury is a recognized complication following gynecologic surgery and can result in hydronephrosis. Anterior lumbar surgery includes procedures like anterior lumbar interbody fusion (ALIF) and total disk replacement (TDR). Anterior approaches to the spine require mobilization of the great vessels and visceral organs. The vascular supply to the ureter arising from the iliac arteries may be compromised during midline retraction of the ureter, which could theoretically lead to ureter ischemia and stricture with subsequent hydronephrosis formation. Methods Potential candidates with previous ALIF or TDR via anterior retroperitoneal access between January 2008 and March 2012 were chosen from those operated on by a single surgeon in a university hospital setting (n = 85). Renal ultrasound evaluation of hydronephrosis was performed on all participants. Simple descriptive and inferential statistics were used to generate results. Results A total of 37 voluntary participants were recruited (23 male, 14 female subjects; average age 51.8 years). The prevalence of hydronephrosis in our population was 0.0% (95% confidence interval 0 to 8.1%). Conclusions Retraction of the ureter across the midline in ALIF and TDR does not result in an increase in hydronephrosis and appears to be a safe surgical technique.

Controls of dissolved organic matter quality: evidence from a large-scale boreal lake survey.

Inland waters transport large amounts of dissolved organic matter (DOM) from terrestrial environments to the oceans, but DOM also reacts en route, with substantial water column losses by mineralization and sedimentation. For DOM transformations along the aquatic continuum, lakes play an important role as they retain waters in the landscape allowing for more time to alter DOM. We know DOM losses are significant at the global scale, yet little is known about how the reactivity of DOM varies across landscapes and climates. DOM reactivity is inherently linked to its chemical composition. We used fluorescence spectroscopy to explore DOM quality from 560 lakes distributed across Sweden and encompassed a wide climatic gradient typical of the boreal ecozone. Six fluorescence components were identified using parallel factor analysis (PARAFAC). The intensity and relative abundance of these components were analyzed in relation to lake chemistry, catchment, and climate characteristics. Land cover, particularly the percentage of water in the catchment, was a primary factor explaining variability in PARAFAC components. Likewise, lake water retention time influenced DOM quality. These results suggest that processes occurring in upstream water bodies, in addition to the lake itself, have a dominant influence on DOM quality. PARAFAC components with longer emission wavelengths, or red-shifted components, were most reactive. In contrast, protein-like components were most persistent within lakes. Generalized characteristics of PARAFAC components based on emission wavelength could ease future interpretation of fluorescence spectra. An important secondary influence on DOM quality was mean annual temperature, which ranged between -6.2 and +7.5 °C. These results suggest that DOM reactivity depends more heavily on the duration of time taken to pass through the landscape, rather than temperature. Projected increases in runoff in the boreal region may force lake DOM toward a higher overall amount and proportion of humic-like substances.

High-resolution structures of the IgM Fc domains reveal principles of its hexamer formation.

IgM is the first antibody produced during the humoral immune response. Despite its fundamental role in the immune system, IgM is structurally only poorly described. In this work we used X-ray crystallography and NMR spectroscopy to determine the atomic structures of the constant IgM Fc domains (Cµ2, Cµ3, and Cµ4) and to address their roles in IgM oligomerization. Although the isolated domains share the typical Ig fold, they differ substantially in dimerization properties and quaternary contacts. Unexpectedly, the Cµ4 domain and its C-terminal tail piece are responsible and sufficient for the specific polymerization of Cµ4 dimers into covalently linked hexamers of dimers. Based on small angle X-ray scattering data, we present a model of the ring-shaped Cµ4 structure, which reveals the principles of IgM oligomerization.

An aspartate and a water molecule mediate efficient acid-base catalysis in a tailored antibody pocket.

Design of catalysts featuring multiple functional groups is a desirable, yet formidable goal. Antibody 13G5, which accelerates the cleavage of unactivated benzisoxazoles, is one of few artificial enzymes that harness an acid and a base to achieve efficient proton transfer. X-ray structures of the Fab-hapten complexes of wild-type 13G5 and active-site variants now afford detailed insights into its mechanism. The parent antibody preorganizes Asp(H35) and Glu(L34) to abstract a proton from substrate and to orient a water molecule for leaving group stabilization, respectively. Remodeling the environment of the hydrogen bond donor with a compensatory network of ordered waters, as seen in the Glu(L34) to alanine mutant, leads to an impressive 10(9)-fold rate acceleration over the nonenzymatic reaction with acetate, illustrating the utility of buried water molecules in bifunctional catalysis. Generalization of these design principles may aid in creation of catalysts for other important chemical transformations.

Inclinação profissional e personalidade: estudo de correlação entre medidas desses construtos / Professional tendency and personality: research on the correlation among measures of these constructs / Inclinación profesional y personalidad: estudio de correlación entre medidas de estos constructos

Este trabalho pretende estudar a validade concorrente entre o 16PF - Questionário Fatorial da Personalidade e o BBT - Teste de Fotos de Profissões. O BBT é um teste projetivo, que se destina à apreensão do perfil de inclinação profissional, considerando oito fatores pulsionais. Apesar de o BBT ter sido concebido para adolescentes, estudos recentes mostraram que também pode ser empregado em adultos no contexto da orientação de carreira, coaching e seleção de pessoal. Enquanto o 16PF teve sua origem na análise fatorial, a construção do BBT se baseou nos pressupostos teóricos de Szondi sobre a estrutura pulsional das doenças mentais, com base em estudos clínicos com pacientes psiquiátricos. Embora os dois instrumentos partam de pressupostos teóricos muito diferentes, a estrutura fatorial do 16PF se assemelha em grande parte aos fatores pulsionais avaliados pelo BBT. Participaram do estudo 87 profissionais (35 homens e 52 mulheres) oriundos de diversas empresas, com idade média de 29,4 anos (DP=8,2). Os resultados confirmaram as hipóteses de pesquisa no nível de significância 0,05.

This work has the presentation of the result of the convergent correlation research between 16PF - The Sixteen Personality Factor Questionnaire and the BBT - Profession Photos Test as objective. The BBT is a projective test destined to apprehend the vocational profile for the purpose of vocational guidance, considering eight drive needs or factors. Although the BBT was designed to be used with adolescents, recent work has shown that it is also useful in the context of career counseling coaching and selection of employees. While the 16PF had its origin in the factorial analysis, BBT's development is based on Szondi's theoretical framework, the drive theory of mental diseases, created upon clinical research with psychiatric patients. Although both instruments are based on very different theories, the factorial structure of the 16PF resembles largely to the drive factors evaluated in BBT. The participants were 87 employees (35 men and 52 women) derived from navigation companies and costal traffic, chemical and information technology segments, aged around 29,4 years (SD=8,2). The results obtained in the correlation study confirmed the hypotheses to the convergence between both instruments at the significance level of 0,05.

Este trabajo pretende estudiar la validez concurrente entre el 16PF - Cuestionario Factorial de la Personalidad y el BBT - Prueba de Fotos de Profesiones. El BBT es una prueba proyectiva, que se destina a la aprehensión del perfil de inclinación profesional, considerando ocho factores impulsivos. A pesar del BBT haber sido concebido para adolescentes, estudios recientes mostraron que también puede ser empleado en adultos en el contexto de la orientación de carrera, coaching y selección de personal. Mientras el 16PF tuvo su origen en el análisis factorial, la construcción del BBT se basó en los presupuestos teóricos de Szondi sobre la estructura de impulso de las enfermedades mentales, con base en estudios clínicos con pacientes psiquiátricos. Aunque los dos instrumentos partan de presupuestos teóricos muy diferentes, la estructura factorial del 16PF se asemeja en gran parte a los factores de impulso evaluados por el BBT. Participaron del estudio 87 profesionales (35 hombres y 52 mujeres) oriundos de diversas empresas, con edad Media de 29,4 años (DP=8,2). Los resultados confirmaron las hipótesis de pesquisa en el nivel de significación 0,05

Structural reorganization and preorganization in enzyme active sites: comparisons of experimental and theoretically ideal active site geometries in the multistep serine esterase reaction cycle.

Many enzymes catalyze reactions with multiple chemical steps, requiring the stabilization of multiple transition states during catalysis. Such enzymes must strike a balance between the conformational reorganization required to stabilize multiple transition states of a reaction and the confines of a preorganized active site in the polypeptide tertiary structure. Here we investigate the compromise between structural reorganization during the catalytic process and preorganization of the active site for a multistep enzyme-catalyzed reaction, the hydrolysis of esters by the Ser-His-Asp/Glu catalytic triad. Quantum mechanical transition states were used to generate ensembles of geometries that can catalyze each individual step in the mechanism. These geometries are compared to each other by superpositions of catalytic atoms to find "consensus" geometries that can catalyze all steps with minimal rearrangement. These consensus geometries are found to be excellent matches for the natural active site. Preorganization is therefore found to be the major defining characteristic of the active site, and reorganizational motions often proposed to promote catalysis have been minimized. The variability of enzyme active sites observed by X-ray crystallography was also investigated empirically. A catalog of geometrical parameters relating active site residues to each other and to bound inhibitors was collected from a set of crystal structures. The crystal-structure-derived values were then compared to the ranges found in quantum mechanically optimized structures along the entire reaction coordinate. The empirical ranges are found to encompass the theoretical ranges when thermal fluctuations are taken into account. Therefore, the active sites are preorganized to a geometry that can be objectively and quantitatively defined as minimizing conformational reorganization while maintaining optimal transition state stabilization for every step during catalysis. The results provide a useful guiding principle for de novo design of enzymes with multistep mechanisms.

Conformational isomerism can limit antibody catalysis.

Ligand binding to enzymes and antibodies is often accompanied by protein conformational changes. Although such structural adjustments may be conducive to enzyme catalysis, much less is known about their effect on reactions promoted by engineered catalytic antibodies. Crystallographic and pre-steady state kinetic analyses of antibody 34E4, which efficiently promotes the conversion of benzisoxazoles to salicylonitriles, show that the resting catalyst adopts two interconverting active-site conformations, only one of which is competent to bind substrate. In the predominant isomer, the indole side chain of Trp(L91) occupies the binding site and blocks ligand access. Slow conformational isomerization of this residue, on the same time scale as catalytic turnover, creates a deep and narrow binding site that can accommodate substrate and promote proton transfer using Glu(H50) as a carboxylate base. Although 34E4 is among the best catalysts for the deprotonation of benzisoxazoles, its efficiency appears to be significantly limited by this conformational plasticity of its active site. Future efforts to improve this antibody might profitably focus on stabilizing the active conformation of the catalyst. Analogous strategies may also be relevant to other engineered proteins that are limited by an unfavorable conformational pre-equilibrium.

Prevalence of nephrolithiasis in patients with ileal bladder substitutes.

OBJECTIVES: To assess the effect of ileal bladder substitutes with preservation of the ileocecal valve and distal 25 cm of ileum on nephrolithiasis. METHODS: We reviewed a consecutive series of 518 patients (44 women and 474 men) with ileal orthotopic bladder substitution in whom 55 to 65 cm of ileum was resected but with preservation of the ileocecal valve and distal 25 cm of ileum, to determine prevalence of nephrolithiasis as well as bicarbonate, base excess, creatinine levels, and urinary pH at time of stone diagnosis and 2 years before it. RESULTS: Four male patients with a median age of 66 years (range, 50 to 70 years) developed nephrolithiasis after ileal bladder substitute, for a total of five calculi. The prevalence of nephrolithiasis in this retrospective cohort is thus 1% (5 of 518). They developed the calculi after a median follow-up of 8 years (range, 4 to 17 years). The four patients were diagnosed with calculi at 2.3, 3, 10, 10.3, and 14 years after bladder substitute. Two of the stones were uric acid calculi; the remaining three were calcium oxalate. None of our patients were acidotic or had elevated serum creatinines at time of stone formation. Urinary pH determined once in spontaneously voided urine at the time of stone diagnosis was pH 6.0 for the two uric acid calculi and pH 7.0 for the remaining calculi. CONCLUSIONS: The present study demonstrates a low prevalence of calculi in our cohort.

Medidas ipsativas na avaliação psicológica / Ipsative measures in psychological evaluation

O objetivo do presente artigo é fomentar a discussão sobre os instrumentos de avaliação psicológica no formato de escolha forçada multidimensional, ou medida ipsativa. A medida ispsativa é obtida por meio da ordenação de itens ou quando o respondente deve escolher os itens que "mais se parecem comigo" e itens "que menos se parecem comigo" em um conjunto de itens igualmente socialmente desejáveis. Esse formato contribui para a resistência ao falseamento das respostas ao dificultar a atribuição de um valor maior a si mesmo em cada construto contido em cada item. O artigo discute a possibilidade de se submeter dados ipsativos a critérios de validação psicométricos sob a ótica da Teoria Clássica dos Itens. As limitações dos dados ipsativos devem ser levadas em consideração ao se determinar as propriedades internas dos instrumentos, pois o valor das medidas ipsativas supera suas limitações psicométricas quando há risco de falseamento de respostas.

This article aims to promote the discussion on the multidimensional force choice instruments, or ipsative measure, in psychological evaluation. Measure can be ipsative through the properties of the item response format such as rank-ordered scales or through forced choice responses in which the respondent must choose items that are "most like me" or "less like me" from a set of items with equal social desirability. The forced choice format was designed to control response distortions due to social desirability, by means of attributing greater value to oneself to each latent construct, represented by the items contained in each item set, with equivalent social desirability value. The article discusses psychometric limitations of ipsative measures considering the Classic Test Theory, which must be taken into account at the determination of internal properties of the instruments, since its value overcomes its limitations, when prevention of item response distortion is needed.

Extracorporeal shock wave lithotripsy of lower calyx calculi: how much is treatment outcome influenced by the anatomy of the collecting system?

OBJECTIVES: Extracorporeal shock wave lithotripsy (ESWL) of lower calyx stones has been criticized because of the high incidence of residual fragments. Controversial results have been reported regarding the stone-free rate after ESWL depending on the influence of the collecting system anatomy on stone clearance. Therefore we evaluated our stone-free rate after ESWL of lower calyx stones and searched for correlations to various anatomic parameters of the collecting system. METHODS: Ninety-six patients with isolated lower calyx stones treated exclusively with ESWL (Dornier HM3) were evaluated 3 mo postoperatively. The results were correlated with the following anatomic parameters of the collecting system as determined from the pretreatment intravenous urography: (1) lower infundibulum width, (2) lower infundibulum length, (3) infundibulopelvic angle, (4) volume of the collecting system. Follow-ups were performed 24 h after ESWL with an abdominal plain film and 3 mo postoperatively with a urography or abdominal plain X-ray together with renal ultrasound. RESULTS: Three months postoperatively, 68% of all patients were stone free, including 69% of the patients with stones initially < or =1 cm, and 67% of the patients with stones >1 cm. Stone-free patients compared with patients having residual fragments had no significant differences in infundibulum width, infundibulum length, infundibulopelvic angle, or collecting system volume. CONCLUSIONS: A stone-free rate 3 mo after ESWL of 68% overall justifies ESWL as a possible treatment option for lower calyx stones. Influence of the collecting system anatomy on disintegrate clearance from the lower calyx could not be demonstrated.

Lasers for lower urinary tract symptoms secondary to benign prostatic hyperplasia: when is the fuss worth it?

In the recent past, several endoscopic procedures using laser technology have evolved for the treatment of benign prostatic hyperplasia. The term "laser treatment of the prostate" comprises a variety of different application systems, different laser wavelengths, and different surgical techniques to eliminate bladder outlet obstruction. The aim of laser prostatectomy is to be less invasive than transurethral electroresection, but equally effective. Promising short-term results led to a booming laser decade in the 1990s, stimulating the development of several devices. However, the emergence of medium-term data has shown that some of these techniques did not stand the test of time due to the lack of long-term efficacy, unacceptable morbidity, and high retreatment rates. Nevertheless, the results of transurethral resection of the prostate are challenged by some of the newer laser devices, putting the so-called "gold standard" into question.