Devising Synthetic Reaction Cycles for Dissipative Nonequilibrium Self-Assembly

Fuel-driven reaction cycles are found in biological systems to control the assembly and disassembly of supramolecular materials such as the cytoskeleton. Fuel molecules can bind noncovalently to a self-assembling building block or they can react with it, resulting in covalent modifications. Overall the fuel can either switch the self-assembly process on or off. Here, a closer look is taken at artificial systems that mimic biological systems by making and breaking covalent bonds in a self-assembling motif. The different chemistries used so far are highlighted in chronological order and the pros and cons of each system are discussed. Moreover, the desired traits of future reaction cycles, their fuels, and waste management are outlined, and two chemistries that have not been explored up to now in chemically fueled dissipative self-assembly are suggested.     

Comprehension and navigation of networked hypertexts

This study aims to investigate secondary school students' reading comprehension and navigation of networked hypertexts with and without a graphic overview compared to linear digital texts. Additionally, it was studied whether prior knowledge, vocabulary, verbal, and visual working memory moderated the relation between text design and comprehension. Therefore, 80 first‐year secondary school students read both a linear text and a networked hypertext with and without a graphical overview. Logfiles registered their navigation. After reading the text, students answered textbased multiple choice questions and drew mindmaps to assess their structural knowledge of each text content. It was found that both textbased and structural knowledge were lower after reading a networked hypertext than a linear text, especially in students with lower levels of vocabulary. Students took generally more time to read the hypertext than the linear text. We concluded that networked hypertexts are more challenging to read than linear texts and that students may benefit from explicit training on how to read hypertexts.     

The cinnamon-oil ingredient trans-cinnamaldehyde fails to target Campylobacter jejuni strain KC 40 in the broiler chicken cecum despite marked in vitro activity

Campylobacter jejuni is the most common bacterial cause of diarrheal disease in humans worldwide, with poultry products being a major source. Therefore, strategies to decrease Campylobacter colonization during primary production might aid in reducing the number of human campylobacteriosis cases. Several plant-derived compounds have been reported to possess anti-Campylobacter properties in vitro, so they could be promising candidates to reduce Campylobacter colonization in broiler chickens. To test this hypothesis, selected plant-derived antimicrobials (caffeic, gallic, protocatechuic, and vanillic acids, epigallocatechin gallate, trans-cinnamaldehyde, and thymol) were screened for anti-Campylobacter activity by determining MICs and setting up time-kill curves for C. jejuni strain KC 40. These experiments revealed marked antibacterial activity, especially for the cinnamon oil ingredient trans-cinnamaldehyde (CIN). This compound was tested in a broiler chick seeder model; it was added to the feed in coated form at an effective concentration of 0.3 % from day-of-hatch for the entire 22-day duration of the experiment. At 14 days of age, one-third of the birds were inoculated with C. jejuni strain KC 40 and served as seeders. CIN was not able to reduce cecal Campylobacter colonization in this model, which was confirmed in a cecal loop experiment. Despite CIN concentrations much higher than the MIC, C. jejuni numbers were not reduced compared with those in nontreated ceca at 2 and 24 h after injection. In conclusion, this study shows a marked discrepancy between in vitro and in vivo activity of CIN against C. jejuni strain KC 40.     

Hydroelastic Behavior of a Floating Ring-Shaped Plate

The interaction between incident surface water waves and floating elastic plate is studied. This paper considers the diffraction of plane incident waves on a floating flexible ring-shaped plate and its response to the incident waves. An analytic and numerical study of the hydroelastic behavior of the plate is presented. An integro-differential equation is derived for the problem and an algorithm of its numerical solution is proposed. The representation of the solution as a series of Hankel functions is the key ingredient of the approach. The problem is first formulated. The main integro-differential equation is derived on the basis of the Laplace equation and thin-plate theory. The free-surface elevation, plate deflection and Green’s function are expressed in polar coordinates as superpositions of Hankel and Bessel functions, respectively. These expressions are used in a further analysis of the integro-differential equation. The problem is solved for two cases of water depth infinite and finite. For the coefficients in the case of infinite depth a set of algebraic equations is obtained, yielding an approximate solution. Then a solution is obtained for the general and most interesting case of finite water depth analogously in the seventh section. The exact solution might be approximated by taking into account a finite number of the roots of the plate dispersion relation. Also, the influence of the plate’s motion on wave propagation in the open water field and within the gap of the ring is studied. Numerical results are presented for illustrative purposes.     

Risk factors for delayed graft function in cadaveric kidney transplantation: a prospective study of renal function and graft survival after preservation with University of Wisconsin solution in multi-organ donors. European Multicenter Study Group

BACKGROUND: Delayed graft function (DGF) remains an important complication in renal transplantation. In this multicenter study, we investigated the influence of donor and recipient factors on the occurrence of DGF and DGF's effect on long-term graft survival. METHODS: A total of 547 transplanted kidney allografts, retrieved from multi-organ donors, were analyzed, and results were compared with literature on kidney-only donors. RESULTS: Median follow-up of patients without graft failure was 3.4 years. Twenty-four percent of the recipients developed DGF. In univariate analysis, the following factors significantly increased the incidence of DGF: (a) among the donor factors, mean creatinine level >120 micromol/L and prolonged cold ischemia time (CIT); and (b) among the recipient factors, previous transplant(s), no intraoperative use of mannitol, poor quality of reperfusion, absence of intraoperative diuresis, and pretransplant anuria or oliguria. After stepwise logistic regression, donor age, CIT, recipient's number of previous transplants, and intraoperative diuresis proved to be of independent prognostic value for the occurrence of DGF. Overall graft survival was 91%, 87%, and 72% at 3 months, 1 year, and 4 years after transplantation, respectively. In case of DGF, graft survival was approximately 10% lower when compared with cases with immediate graft function (P<0.001). No difference in incidence of DGF was found between grafts of multi-organ donors and kidney-only donors. CONCLUSIONS: DGF results in an approximately 10% higher rate of graft failure. DGF incidence can be reduced by the administration of mannitol during transplantation, which minimizes CIT and optimizes donor management. Grafts from multi-organ donors and kidney-only donors appear to be of equal quality.     

Autobiographical memory specificity and affect regulation: An experimental approach.

This study investigated J. M. G. Williams's (1996) affect-regulation hypothesis that level of specificity of autobiographical memory (AM) is used to minimize negative affect. It was found that a negative event leads to more reports of subjective stress in high- as compared with low-specific participants. Also, afterward, high-specific participants rated their unprompted memories for the event as more unpleasant. The results indicate that, relative to high specificity, being less specific in the retrieval of AMs is associated with less affective impact of a negative event. Results are discussed within the affect-regulation model. It is suggested that future research take a more functional perspective on AM specificity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Case report: 17 alpha-hydroxylase/17,20-lyase deficiency: a rare cause of endocrine hypertension

The combination of hypertension, hypokaliemia, and male pseudohermaphroditism or amenorrhea must prompt a search for a rare adrenal enzymatic defect, 17 alpha-hydroxylase/17,20-lyase deficiency. This is a report of the observation of a male patient in whom this rare deficit was diagnosed in adulthood on the basis of lifelong ambiguous external genitalia, hypogonadism, severe hypertension, bilateral adrenal hyperplasia, and biological markers evoking an excess of mineralocorticoids without hyperaldosteronism.     

Complications of laparoscopy: a prospective multicentre observational study

Extrahepatic obstruction of the portal vein is a well known cause of portal hypertension in childhood, that causes severe morbidity. We evaluated 34 children (24 boys, 10 girls, age 4.5 months to 12 years, mean 5.5 +/- 3.8 years) with this diagnosis, to define the clinical picture, laboratory changes, diagnostic tools and therapeutic modalities. Gastrointestinal bleeding was the commonest mode of presentation (64.7%), with the second being splenomegaly. The cause of the obstruction could be determined in 38.2% (13/34) of the subjects. At the beginning of the study the main diagnostic procedure was splenoportography although in more recent years pulsed duplex Doppler ultrasonography has been used. The follow up period was median of 5 years (range 1-11 years). The mean number of bleeding episodes was 4.7 +/- 5.9 (range 1-26), while nine patients never bled. There was no mortality. Ten patients underwent surgery, while sclerotherapy was performed on 10. Twenty-one patients received beta-blocker drugs. No difference was found among these therapeutic modalities. It is well established that the major risk for children with extrahepatic portal vein obstruction is gastrointestinal bleeding which is tolerated quite well. Surgery should be indicated only in children where bleeding cannot be controlled by medical means including sclerotherapy.