Plasma leptin turnover rates in lean and obese Zucker rats

Conscious female adult lean and obese Zucker rats were injected through the jugular vein with radioactive iodine-labeled murine leptin; in the ensuing 8 min, four blood samples were sequentially extracted from the carotid artery. The samples were used in a modified RIA for leptin, in which paired tubes received the same amount of either labeled or unlabeled leptin, thus allowing us to estimate both leptin levels and specific radioactivity. The data were used to determine the decay curve parameters from which the half-life of leptin (5.46 ± 0.23 min for lean rats and 6.99 ± 0.75 min for obese rats) as well as the size of its circulating pool (32 pmol/kg for lean rats and 267 pmol/kg for obese rats) and the overall degradation rate (96 fkat/kg for lean rats and 645 fkat/kg for obese rats) were estimated. These values are consistent with the hormonal role of leptin and the need for speedy changes in its levels in response to metabolic challenge.

Spatial correlations and cross sections of clusters in the A + B -> 0 reaction

We consider the distribution of cross sections of clusters and the density-density correlation functions for the A+B¿0 reaction. We solve the reaction-diffusion equations numerically for random initial distributions of reactants. When both reactant species have the same diffusion coefficients the distribution of cross sections and the correlation functions scale with the diffusion length and obey superuniversal laws (independent of dimension). For different diffusion coefficients the correlation functions still scale, but the scaling functions depend on the dimension and on the diffusion coefficients. Furthermore, we display explicitly the peculiarities of the cluster-size distribution in one dimension.

Reaction-diffusion fronts under stochastic advection

We study front propagation in stirred media using a simplified modelization of the turbulent flow. Computer simulations reveal the existence of the two limiting propagation modes observed in recent experiments with liquid phase isothermal reactions. These two modes respectively correspond to a wrinkled although sharp propagating interface and to a broadened one. Specific laws relative to the enhancement of the front velocity in each regime are confirmed by our simulations.

Network-based scoring system for genome-scale metabolic reconstructions

Background: Network reconstructions at the cell level are a major development in Systems Biology. However, we are far from fully exploiting its potentialities. Often, the incremental complexity of the pursued systems overrides experimental capabilities, or increasingly sophisticated protocols are underutilized to merely refine confidence levels of already established interactions. For metabolic networks, the currently employed confidence scoring system rates reactions discretely according to nested categories of experimental evidence or model-based likelihood. Results: Here, we propose a complementary network-based scoring system that exploits the statistical regularities of a metabolic network as a bipartite graph. As an illustration, we apply it to the metabolism of Escherichia coli. The model is adjusted to the observations to derive connection probabilities between individual metabolite-reaction pairs and, after validation, to assess the reliability of each reaction in probabilistic terms. This network-based scoring system uncovers very specific reactions that could be functionally or evolutionary important, identifies prominent experimental targets, and enables further confirmation of modeling results. Conclusions: We foresee a wide range of potential applications at different sub-cellular or supra-cellular levels of biological interactions given the natural bipartivity of many biological networks.

The prediction of chemical reactivity from first principles: Collision and reaction dynamics

Aquest treball fa una revisió de mesures experimentals i càlculs teòrics sobre la dinàmica de col·lisions i reaccions moleculars. Els experiments se centren en col·lisions, a energies intermèdies, que involucren sistemes del tipus ió-àtom i iómolècula, per les quals es mesuren seccions eficaces totals, estat a estat, així com aquelles que discerneixen les diferents contribucions del moment angular d'espín. Els resultats obtinguts s'interpreten satisfactòriament en termes d'acoblaments no adiabàtics entre els diferents estats electrònics dels sistemes col·lisionants. Els càlculs teòrics utilitzen la metodologia quasiclàssica, així com metodologies mecanoquàntiques recentment desenvolupades, tant aproximades com exactes. S'han obtingut resultats totalment convergits per sistemes tipus, mentre que s'han analitzat, de manera detallada i extensiva, les característiques dinàmiques de sistemes triatòmic, tetraatòmic i pentaatòmic.

Experimental evidence of localized oscillations in the photosensitive chlorine dioxide-iodine-malonic acid reaction

The interaction between Hopf and Turing modes has been the subject of active research in recent years. We present here experimental evidence of the existence of mixed Turing-Hopf modes in a two-dimensional system. Using the photosensitive chlorine dioxide-iodine-malonic acid reaction (CDIMA) and external constant background illumination as a control parameter, standing spots oscillating in amplitude and with hexagonal ordering were observed. Numerical simulations in the Lengyel-Epstein model for the CDIMA reaction confirmed the results.

Implementation of raltegravir in routine clinical practice: selection criteria for choosing this drug, virologic response rates, and characteristics of failures.

BACKGROUND: Raltegravir (RAL) achieved remarkable virologic suppression rates in randomized-clinical trials, but today efficacy data and factors for treatment failures in a routine clinical care setting are limited. METHODS: First, factors associated with a switch to RAL were identified with a logistic regression including patients from the Swiss HIV Cohort Study with a history of 3 class failure (n = 423). Second, predictors for virologic outcome were identified in an intent-to-treat analysis including all patients who received RAL. Last observation carried forward imputation was used to determine week 24 response rate (HIV-1 RNA >or= 50 copies/mL). RESULTS: The predominant factor associated with a switch to RAL in patients with suppressed baseline RNA was a regimen containing enfuvirtide [odds ratio 41.9 (95% confidence interval: 11.6-151.6)]. Efficacy analysis showed an overall response rate of 80.9% (152/188), whereas 71.8% (84/117) and 95.8% (68/71) showed viral suppression when stratified for detectable and undetectable RNA at baseline, respectively. Overall CD4 cell counts increased significantly by 42 cells/microL (P < 0.001). Characteristics of failures were a genotypic sensitivity score of the background regimen <or=1, very low RAL plasma concentrations, poor adherence, and high viral load at baseline. CONCLUSIONS: Virologic suppression rates in our routine clinical care setting were promising and comparable with data from previously published randomized-controlled trials.

Prognostic role of KRAS and BRAF in stage II and III resected colon cancer: results of the translational study on the PETACC-3, EORTC 40993, SAKK 60-00 trial.

PURPOSE: Mutations within the KRAS proto-oncogene have predictive value but are of uncertain prognostic value in the treatment of advanced colorectal cancer. We took advantage of PETACC-3, an adjuvant trial with 3,278 patients with stage II to III colon cancer, to evaluate the prognostic value of KRAS and BRAF tumor mutation status in this setting. PATIENTS AND METHODS: Formalin-fixed paraffin-embedded tissue blocks (n = 1,564) were prospectively collected and DNA was extracted from tissue sections from 1,404 cases. Planned analysis of KRAS exon 2 and BRAF exon 15 mutations was performed by allele-specific real-time polymerase chain reaction. Survival analyses were based on univariate and multivariate proportional hazard regression models. RESULTS: KRAS and BRAF tumor mutation rates were 37.0% and 7.9%, respectively, and were not significantly different according to tumor stage. In a multivariate analysis containing stage, tumor site, nodal status, sex, age, grade, and microsatellite instability (MSI) status, KRAS mutation was associated with grade (P = .0016), while BRAF mutation was significantly associated with female sex (P = .017), and highly significantly associated with right-sided tumors, older age, high grade, and MSI-high tumors (all P < 10(-4)). In univariate and multivariate analysis, KRAS mutations did not have a major prognostic value regarding relapse-free survival (RFS) or overall survival (OS). BRAF mutation was not prognostic for RFS, but was for OS, particularly in patients with MSI-low (MSI-L) and stable (MSI-S) tumors (hazard ratio, 2.2; 95% CI, 1.4 to 3.4; P = .0003). CONCLUSION: In stage II-III colon cancer, the KRAS mutation status does not have major prognostic value. BRAF is prognostic for OS in MS-L/S tumors.

Estimation of soil nitrate in the spring as a basis for adjustment of nitrogen fertiliser rates

Selostus: Maassa olevan nitraattitypen arviointi simulointimallin avulla

Trace element supplementation modulates pulmonary infection rates after major burns: a double-blind, placebo-controlled trial.

Infections remain the leading cause of death after major burns. Trace elements are involved in immunity and burn patients suffer acute trace element depletion after injury. In a previous nonrandomized study, trace element supplementation was associated with increased leukocyte counts and shortened hospital stays. This randomized, placebo-controlled trial studied clinical and immune effects of trace element supplements. Twenty patients, aged 40 +/- 16 y (mean +/- SD), burned on 48 +/- 17% of their body surfaces, were studied for 30 d after injury. They consumed either standard trace element intakes plus supplements (40.4 micromol Cu, 2.9 micromol Se, and 406 micromol Zn; group TE) or standard trace element intakes plus placebo (20 micromol Cu, 0.4 micromol Se, and 100 micromol Zn; group C) for 8 d. Demographic data were similar for both groups. Mean plasma copper and zinc concentrations were below normal until days 20 and 15, respectively (NS). Plasma selenium remained normal for group TE but decreased for group C (P < 0.05 on days 1 and 5). Total leukocyte counts tended to be higher in group TE because of higher neutrophil counts. Proliferation to mitogens was depressed compared with healthy control subjects (NS). The number of infections per patient was significantly (P < 0.05) lower in group TE (1.9 +/- 0.9) than in group C (3.1 +/- 1.1) because of fewer pulmonary infections. Early trace element supplementation appears beneficial after major burns; it was associated with a significant decrease in the number of bronchopneumonia infections and with a shorter hospital stay when data were normalized for burn size.

Fracture rates of IPS Empress all-ceramic crowns: a systematic review.

Purpose: The aim of this study was to evaluate the clinical fracture rate of crowns fabricated with the pressable, leucite-reinforced ceramic IPS Empress, and relate the results to the type of tooth restored. Materials and Methods: The database SCOPUS was searched for clinical studies involving full-coverage crowns made of IPS Empress. To assess the fracture rate of the crowns in relation to the type of restored tooth and study, Poisson regression analysis was used. Results: Seven clinical studies were identified involving 1,487 adhesively luted crowns (mean observation time: 4.5 +/- 1.7 years) and 81 crowns cemented with zinc-phosphate cement (mean observation time: 1.6 +/- 0.8 years). Fifty-seven of the adhesively luted crowns fractured (3.8%). The majority of fractures (62%) occurred between the third and sixth year after placement. There was no significant influence regarding the test center on fracture rate, but the restored tooth type played a significant role. The hazard rate (per year) for crowns was estimated to be 5 in every 1,000 crowns for incisors, 7 in every 1,000 crowns for premolars, 12 in every 1,000 crowns for canines, and 16 in every 1,000 crowns for molars. One molar crown in the zinc-phosphate group fractured after 1.2 years. Conclusion: Adhesively luted IPS Empress crowns showed a low fracture rate for incisors and premolars and a somewhat higher rate for molars and canines. The sample size of the conventionally luted crowns was too small and the observation period too short to draw meaningful conclusions. Int J Prosthodont 2010;23:129-133.

Human papilloma virus type and recurrence rate after surgical clearance of anal condylomata acuminata.

BACKGROUND: Anal condylomata acuminata (ACA) are caused by human papilloma virus (HPV) infection which is transmitted by close physical and sexual contact. The result of surgical treatment of ACA has an overall success rate of 71% to 93%, with a recurrence rate between 4% and 29%. The aim of this study was to assess a possible association between HPV type and ACA recurrence after surgical treatment. METHODS: We performed a retrospective analysis of 140 consecutive patients who underwent surgery for ACA from January 1990 to December 2005 at our tertiary University Hospital. We confirmed ACA by histopathological analysis and determined the HPV typing using the polymerase chain reaction. Patients gave consent for HPV testing and completed a questionnaire. We looked at the association of ACA, HPV typing, and HIV disease. We used chi, the Monte Carlo simulation, and Wilcoxon tests for statistical analysis. RESULTS: Among the 140 patients (123 M/17 F), HPV 6 and 11 were the most frequently encountered viruses (51% and 28%, respectively). Recurrence occurred in 35 (25%) patients. HPV 11 was present in 19 (41%) of these recurrences, which is statistically significant, when compared with other HPVs. There was no significant difference between recurrence rates in the 33 (24%) HIV-positive and the HIV-negative patients. CONCLUSIONS: HPV 11 is associated with higher recurrence rate of ACA. This makes routine clinical HPV typing questionable. Follow-up is required to identify recurrence and to treat it early, especially if HPV 11 has been identified.

Variation in thermal performance and reaction norms among populations of Drosophila melanogaster.

The major goal of evolutionary thermal biology is to understand how variation in temperature shapes phenotypic evolution. Comparing thermal reaction norms among populations from different thermal environments allows us to gain insights into the evolutionary mechanisms underlying thermal adaptation. Here, we have examined thermal adaptation in six wild populations of the fruit fly (Drosophila melanogaster) from markedly different natural environments by analyzing thermal reaction norms for fecundity, thorax length, wing area, and ovariole number under ecologically realistic fluctuating temperature regimes in the laboratory. Contrary to expectation, we found only minor differences in the thermal optima for fecundity among populations. Differentiation among populations was mainly due to differences in absolute (and partly also relative) thermal fecundity performance. Despite significant variation among populations in the absolute values of morphological traits, we observed only minor differentiation in their reaction norms. Overall, the thermal reaction norms for all traits examined were remarkably similar among different populations. Our results therefore suggest that thermal adaptation in D. melanogaster predominantly involves evolutionary changes in absolute trait values rather than in aspects of thermal reaction norms.