Rapid diversification of grey mangroves (Avicennia marina) driven by geographic isolation and extreme environmental conditions in the Arabian Peninsula.

Biological systems occurring in ecologically heterogeneous and spatially discontinuous habitats provide an ideal opportunity to investigate the relative roles of neutral and selective factors in driving lineage diversification. The grey mangroves (Avicennia marina) of Arabia occur at the northern edge of the species' range and are subject to variable, often extreme, environmental conditions, as well as historic large fluctuations in habitat availability and connectivity resulting from Quaternary glacial cycles. Here, we analyse fully sequenced genomes sampled from 19 locations across the Red Sea, the Arabian Sea and the Persian/Arabian Gulf (PAG) to reconstruct the evolutionary history of the species in the region and to identify adaptive mechanisms of lineage diversification. Population structure and phylogenetic analyses revealed marked genetic structure correlating with geographic distance and highly supported clades among and within the seas surrounding the Arabian Peninsula. Demographic modelling showed times of divergence consistent with recent periods of geographic isolation and low marine connectivity during glaciations, suggesting the presence of (cryptic) glacial refugia in the Red Sea and the PAG. Significant migration was detected within the Red Sea and the PAG, and across the Strait of Hormuz to the Arabian Sea, suggesting gene flow upon secondary contact among populations. Genetic-environment association analyses revealed high levels of adaptive divergence and detected signs of multi-loci local adaptation driven by temperature extremes and hypersalinity. These results support a process of rapid diversification resulting from the combined effects of historical factors and ecological selection and reveal mangrove peripheral environments as relevant drivers of lineage diversity.

Modeling of a C-end rule peptide adsorbed onto gold nanoparticles.

The RPAR peptide, a prototype C-end Rule (CendR) sequence that binds to neuropilin-1 (NRP-1), has potential therapeutic uses as internalization trigger in anticancer nanodevices. Recently, the functionalization of gold nanoparticles with CendR peptides has been proved to be a successful strategy to target the NRP-1 receptor in prostate cancer cells. In this work, we investigate the influence of two gold surface facets, (100) and (111), on the conformational preferences of RPAR using molecular dynamics simulations. Both clustering and conformational analyses revealed that the peptide backbone becomes very rigid upon adsorption onto gold, which is a very fast and favored process, the only flexibility being attributed to the side chains of the two Arg residues. Thus, the different components of RPAR tend to adopt an elongated shape, which is characterized by the pseudo-extended conformation of both the backbone and the Arg side chains. This conformation is very different from the already known bioactive conformation, indicating that RPAR is drastically affected by the substrate. Interestingly, the preferred conformations of the peptide adsorbed onto gold facets are not stabilized by salt bridges and/or specific intramolecular hydrogen bonds, which represent an important difference with respect to the conformations found in other environments (e.g. the peptide in solution and interacting with NRP-1 receptor). However, the conformational changes induced by the substrate are not detrimental for the use of gold nanoparticles as appropriate vehicles for the transport and targeted delivery of the RPAR. Thus, once their high affinity for the NRP-1 receptor induces the targeted delivery of the elongated peptide molecules from the gold nanoparticles, the lack of intramolecular interactions facilitates their evolution towards the bioactive conformation, increasing the therapeutic efficacy of the peptide.

[Effectiveness of cigarette-pack warning labels in capturing the attention of smokers and nonsmokersEficácia das tarjas de advertência em maços de cigarro para atrair a atenção de fumantes e não fumantes]. / Eficacia de las etiquetas de advertencia en las cajetillas de cigarrillo.

OBJECTIVE: To determine the ability of cigarette-pack warning labels, of the minimum size required by the World Health Organization, to capture the attention of smokers and nonsmokers. METHODS: In this study, 30 smokers and 30 nonsmokers completed a dot-probe task in which they simultaneously observed images of cigarette packs split in two: the top contained the cigarette brand and the bottom contained the warning label. During the task, brain activity was recorded through two event-related potentials of the negative-polarity type--the potential that occurs in the posterior-contralateral zone approximately 200 ms after a stimulus (N2pc) and the sustained posterior contralateral negativity (SPCN) response--which are indicators of early and sustained attention. RESULTS: In both groups, a greater amplitude of N2pc and SPCN potentials was found for the part of the pack containing the cigarette brand. However, during the dot-probe task, reaction times were shorter for the warning label. CONCLUSIONS: These results suggest that, initially, attention is focused on the cigarette brand, and only then on the warning label. The inability of warning labels to capture early-phase attention decreases their effectiveness, especially in smokers. We suggest that warning labels be enlarged to facilitate increased attention response.

OBJETIVO: Determinar a capacidade das tarjas de advertência com o tamanho mínimo exigido pela Organização Mundial da Saúde (OMS) de atrair a atenção de fumantes e não fumantes. MÉTODOS: A amostra do estudo consistiu de 30 fumantes e 30 não fumantes que foram testados com uma tarefa de sondagem (dot-probe task) em que tiveram de observar simultaneamente imagens de um maço de cigarro dividido ao meio: a parte superior continha a marca do cigarro e a parte inferior continha a tarja de advertência. Durante o teste, foi registrada a atividade cerebral com a análise de potenciais evocados relacionados a eventos do tipo potencial negativo que ocorre em cerca de 200 ms na área posterior contralateral ao estímulo (N2pc) e da ocorrência de negatividade contralateral posterior sustentada (SPCN, em inglês), que são indicadores de atenção mais rápida e sustentada. RESULTADOS: Em ambos os grupos de participantes foi observada maior amplitude dos potenciais N2pc e SPCN na parte do maço que continha a marca. Porém, o tempo de reação na tarefa de sondagem foi menor diante da tarja de advertência. CONCLUSÕES: Os resultados deste estudo sugerem que, ao início, a atenção é dirigida à marca do cigarro e depois à tarja de advertência. A incapacidade da tarja de advertência de atrair a atenção nas primeiras fases diminui sua eficácia, sobretudo entre os fumantes. Recomenda-se aumentar o tamanho das tarjas de advertência para estimular um incremento na resposta de atenção.

Cardiovascular risk factors and lifetime risk estimation in HIV-infected patients under antiretroviral treatment in Spain.

BACKGROUND AND OBJECTIVES: Cardiovascular disease is a major concern in HIV-infected patients. Lifetime risk estimations use the risk of developing it over the course of remaining lifetime, and are useful in communicating this risk to young patients. We aim to describe the prevalence of cardiovascular risk factors among a representative sample of HIV-infected subjects under antiretroviral therapy in Spain, and to estimate their lifetime risk of cardiovascular disease. METHODS: Cross-sectional survey about cardiovascular risk factors in 10 HIV units across Spain. Lifetime risk assessed according to Barry was classified in two major categories: low and high lifetime risk. RESULTS: We included 895 subjects, 72% men, median age 45.7 years; median CD4 lymphocyte count 598 cells/µl, median time since HIV diagnosis 11 years, median time on antiretroviral treatment 6.3 years, 87% had undetectable HIV viral load. Tobacco smoking was the most frequent risk factor (54%), followed by dyslipidemia (48.6%) and hypertension (38.6%). Estimated 10-year coronary risk (Framingham/Regicor Risk Score) risk was low ( < 5%) in 78% of the patients, and intermediate (5-10%) in 20%. Lifetime risk estimation showed a high risk profile for 71.4% of the population studied, which was associated with increasing age, prolonged antiretroviral therapy and patient's place of origin. CONCLUSIONS: Modifiable cardiovascular risk factors in this population are very common. There are significant disparities between the low 10-year risk estimated with the Framingham/Regicor score and the higher lifetime risk in HIV patients on antiretroviral therapy. A more aggressive management of modifiable cardiovascular risk factors in these patients seems advisable.

Reinforcement of Acrylamide Hydrogels with Cellulose Nanocrystals Using Gamma Radiation for Antibiotic Drug Delivery.

In this paper, we report the synthesis of acrylamide hydrogels (net-AAm) reinforced with cellulose nanocrystals (CNCs) using gamma radiation, a powerful tool to obtain crosslinked polymers without the use of chemical initiators and crosslinking agents. Some slight changes in the chemical structure and crystallinity of CNCs took place during gamma irradiation without affecting the nanofiller function. In fact, cellulose nanocrystals had a notable influence over the swelling and mechanical properties on the reinforced hydrogels (net-AAm/CNC), obtaining more rigid material since the Young compression modulus increased from 11 kPa for unreinforced net-AAm to 30 kPa for net-AAm/CNC (4% w/w). Moreover, the studies of retention and release of ciprofloxacin (Cx), a quinolone antibiotic drug, showed that reinforced hydrogels were able to load large amounts of ciprofloxacin (1.2-2.8 mg g-1) but they distributed 100% of the drug very quickly (<100 min). Despite this, they exhibited better mechanical properties than the control sample, allowing their handling, and could be used as wound dressings of first response because they can absorb the exudate and at the same time deliver an antibiotic drug directly over the injury.

Potential role of seaweeds in climate change mitigation.

Seaweed (macroalgae) has attracted attention globally given its potential for climate change mitigation. A topical and contentious question is: Can seaweeds' contribution to climate change mitigation be enhanced at globally meaningful scales? Here, we provide an overview of the pressing research needs surrounding the potential role of seaweed in climate change mitigation and current scientific consensus via eight key research challenges. There are four categories where seaweed has been suggested to be used for climate change mitigation: 1) protecting and restoring wild seaweed forests with potential climate change mitigation co-benefits; 2) expanding sustainable nearshore seaweed aquaculture with potential climate change mitigation co-benefits; 3) offsetting industrial CO2 emissions using seaweed products for emission abatement; and 4) sinking seaweed into the deep sea to sequester CO2. Uncertainties remain about quantification of the net impact of carbon export from seaweed restoration and seaweed farming sites on atmospheric CO2. Evidence suggests that nearshore seaweed farming contributes to carbon storage in sediments below farm sites, but how scalable is this process? Products from seaweed aquaculture, such as the livestock methane-reducing seaweed Asparagopsis or low carbon food resources show promise for climate change mitigation, yet the carbon footprint and emission abatement potential remains unquantified for most seaweed products. Similarly, purposely cultivating then sinking seaweed biomass in the open ocean raises ecological concerns and the climate change mitigation potential of this concept is poorly constrained. Improving the tracing of seaweed carbon export to ocean sinks is a critical step in seaweed carbon accounting. Despite carbon accounting uncertainties, seaweed provides many other ecosystem services that justify conservation and restoration and the uptake of seaweed aquaculture will contribute to the United Nations Sustainable Development Goals. However, we caution that verified seaweed carbon accounting and associated sustainability thresholds are needed before large-scale investment into climate change mitigation from seaweed projects.

Peripherally induced human regulatory T cells uncouple Kv1.3 activation from TCR-associated signaling.

Peripherally induced Tregs (iTregs) are being recognized as a functional and physiologically relevant T-cell subset. Understanding the molecular basis of their development is a necessary step before the therapeutic potential of iTreg manipulation can be exploited. In this study, we report that the differentiation of primary human T cells to suppressor iTregs involves the relocation of key proximal TCR signaling elements to the highly active IL-2-Receptor (IL-2-R) pathway. In addition to the recruitment of lymphocyte-specific protein tyrosine kinase (Lck) to the IL-2-R complex, we identified the dissociation of the voltage-gated K(+) channel Kv1.3 from the TCR pathway and its functional coupling to the IL-2-R. The regulatory switch of Kv1.3 activity in iTregs may constitute an important contributing factor in the signaling rewiring associated with the development of peripheral human iTregs and sheds new light upon the reciprocal crosstalk between the TCR and the IL-2-R pathways.

Binary Graft of Poly(N-vinylcaprolactam) and Poly(acrylic acid) onto Chitosan Hydrogels Using Ionizing Radiation for the Retention and Controlled Release of Therapeutic Compounds.

In this study, we carried out the synthesis of a thermo- and pH-sensitive binary graft, based on N-vinylcaprolactam (NVCL) and pH sensitive acrylic acid (AAc) monomers, onto chitosan gels (net-CS) by ionizing radiation. Pre-oxidative irradiation and direct methods were examined, and materials obtained were characterized by FTIR-ATR, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and swelling tests (equilibrium swelling time, critical pH, and temperature). The best synthesis radiation method was the direct method, which resulted in the maximum grafting percentages (~40%) at low doses (10-12 kGy). The main goal of this study was the comparison of the swelling behavior and physicochemical properties of net-CS with those of the binary system (net-CS)-g-NVCL/AAc with the optimum grafting percentage (~30%). This produced a material that showed an upper critical solution temperature (UCST) of 33.5 °C and a critical pH value of 3.8, indicating the system is more hydrophilic at higher temperatures and low pH values. Load and release studies were carried out using diclofenac. The grafted system (32%) was able to load 19.3 mg g-1 of diclofenac and release about 95% within 200 min, in comparison to net-CS, which only released 80% during the same period. When the grafted system was protonated before diclofenac loading, it loaded 27.6 mg g-1. However, the drug was strongly retained in the material by electrostatic interactions and only released about 20%.

A high-quality genome assembly and annotation of the gray mangrove, Avicennia marina.

The gray mangrove [Avicennia marina (Forsk.) Vierh.] is the most widely distributed mangrove species, ranging throughout the Indo-West Pacific. It presents remarkable levels of geographic variation both in phenotypic traits and habitat, often occupying extreme environments at the edges of its distribution. However, subspecific evolutionary relationships and adaptive mechanisms remain understudied, especially across populations of the West Indian Ocean. High-quality genomic resources accounting for such variability are also sparse. Here we report the first chromosome-level assembly of the genome of A. marina. We used a previously release draft assembly and proximity ligation libraries Chicago and Dovetail HiC for scaffolding, producing a 456,526,188-bp long genome. The largest 32 scaffolds (22.4-10.5 Mb) accounted for 98% of the genome assembly, with the remaining 2% distributed among much shorter 3,759 scaffolds (62.4-1 kb). We annotated 45,032 protein-coding genes using tissue-specific RNA-seq data in combination with de novo gene prediction, from which 34,442 were associated to GO terms. Genome assembly and annotated set of genes yield a 96.7% and 95.1% completeness score, respectively, when compared with the eudicots BUSCO dataset. Furthermore, an FST survey based on resequencing data successfully identified a set of candidate genes potentially involved in local adaptation and revealed patterns of adaptive variability correlating with a temperature gradient in Arabian mangrove populations. Our A. marina genomic assembly provides a highly valuable resource for genome evolution analysis, as well as for identifying functional genes involved in adaptive processes and speciation.

Preparation of an adhesive in emulsion for maxillofacial prosthetic.

Maxillofacial prostheses is a dental medicine specialty aimed at restoring anatomical facial defects caused by cancer, trauma or congenital malformations through an artificial device, which is commonly attached to the skin with the help of an adhesive. The purpose of our research was to develop a pressure-sensitive adhesive (PSA) based on acrylic monomers, characterizing and determining its drying kinetics, that is to say the time it takes to lose 50 to 90% of its moisture. The adhesive synthesis was realized by means of emulsion polymerization; the composition of formulations was: (AA-MMA-EA) and (AA-MMA-2EHA) with different molar ratios. The formulation based on (AA-MMA-2EHA) with 50 w% of solids, presented good adhesive properties such as tack, bond strength, and short drying time. We propose this formulation as a PSA, because it offers an alternative for systemically compromised patients, by less irritation compared to organic solvent-based adhesives.

Perception that Mothers and / or Guardians of Overweight or Obese Preschool Children Have of a Text Messaging Program to Support Behaviour Change in their Children.

In most childhood obesity preventive programs, parents are targeted as they are key in achieving lifestyle behavior change in their children. Because their participation is generally low, new technologies, such as text messaging, are being tested to assess if their participation increases. The objective of this study was to determine the perception that mothers of overweight/ obese preschool children have of a textmessaging program developed to support their children's lifestyle behavior change. Text messages were sent to 60 mothers twice a week for 12 weeks; 58 of them said they received all of them. During the process mothers were contacted twice regarding their opinion on all aspects related to the messages. At follow-up, we determined perception by in depth interviews administered to participants. Results show that text messaging implemented in a personalized manner was considered successful in regards to providing useful information to support their children's behavior change.

Academically Oriented Activity Breaks for First-Grade Chilean Students: Development and Pilot Testing Effectiveness.

We developed and pilot tested the effectiveness of a physically active academic program, Active Breaks (AB), whose objective is to increase school time moderate/vigorous physical activity (MVPA) among first graders, through daily 15-minute bouts of MVPA, at the beginning of the first lesson. Initially, 240 cards including one game each were developed and tested in first-grade students from 16 schools in Santiago. Trained observers and school teachers assessed the time, ease, and feasibility of implementation for each card. Barriers and facilitators to implementation were obtained from semistructured interviews to 14 teachers (out of 16). In eight schools (n = 556 students), we compared school time MVPA (with accelerometers) at baseline and follow-up, using test of proportions. One-hundred and twenty cards (games) complied with all aspects. AB were implemented 50% of the time with a duration of 14 minutes (SD = 5). More than 90% of the time, teachers felt competent to conduct AB, and children understood the instructions and enjoyed the activity. The main facilitators included teachers liking physical activity and considering it important, support of principal and school staff, and conducting AB inside the classroom. Barriers included teacher's workload and having to conduct AB during the first lesson. During the 4-month period of implementation, MVPA increased by 1.5 and 1.2 percentage points in boys and girls, respectively. The set of 120 cards is easy and feasible to implement. Moreover, preliminary results suggest they could be effective in increasing MVPA during school time, although studies with longer follow-ups are needed to assess the validity of these findings.

A DNA mini-barcode for marine macrophytes.

Studies focusing on marine macrophyte metabarcoding from environmental samples are scarce, due to the lack of a universal barcode for these taxa, and to their poor representation in DNA databases. Here, we searched for a short barcode able to identify marine macrophytes from tissue samples; then, we created a DNA reference library which was used to identify macrophytes in eDNA from coastal sediments. Barcoding of seagrasses, mangroves and marine macroalgae (Chlorophyta, Rhodophyta and Phaeophyceae) was tested using 18 primer pairs from six barcoding genes: the plant barcodes rbcL, matK and trnL, plus the genes ITS2, COI and 18S. The 18S gene showed the highest universality among marine macrophytes, amplifying 95%-100% of samples; amplification performance of the other barcodes was limited. Taxonomy was assigned using a phylogeny-based approach to create an 18S DNA reference library. Macrophyte tissue sequences were accurately identified within their phyla (88%), order (76%), genus (71%) and species (23%). Nevertheless, out of 86 macrophytes tested, only 48% and 15% had a reference sequence at genus and at species level, respectively. Identification at these levels can be improved by more inclusive reference libraries. Using the 18S mini-barcode and the reference library, we recovered eDNA from 21 marine macrophytes in sediments, demonstrating the barcode's ability to trace primary producers that contribute to blue carbon. We expect this barcode to also be useful for other ecological questions, such as tracing macro primary producers in marine food webs.

Perception of humanized childbirth in patients in the puerperium period. / Percepción del parto humanizado en pacientes en periodo de puerperio.

BACKGROUND: The patient's perception of humanized childbirth care is important to identify and avoid data suggestive of obstetric violence, which is all conduct, action or omission, performed by health personnel that affect the body and the reproductive processes of women, expressed in dehumanized treatment. OBJECTIVE: To know the level of perception of humanized childbirth in patients in the postpartum period in the OB-Gyn Service at the Hospital General de Zona No. 1 from the Instituto Mexicano del Seguro Social. MATERIAL AND METHODS: Observational study in 190 patients in the immediate puerperium. Demographic variables were measured and the level of perception of humanized delivery was analyzed (inadequate: 18-32 points; regular: 35-53 points; adequate: 54-72 points). Descriptive statistics and association measures were used. Informed written consent of the participants was signed and authorized with the registration number R-2018-301-020. RESULTS: The overall perception of humanized delivery was inadequate in 56.8%, regular in 34.7% and adequate in 8.4%. CONCLUSION: The perception of humanized childbirth in patients who are in immediate postpartum in our hospital is inappropriate, since they were not provided with the appropriate guidance, information on pain management, choosing a position of labor, and having the possibility that a companion is present during the process.

INTRODUCCIÓN: La percepción de las pacientes sobre la atención del parto humanizado es importante para identificar y evitar datos que sugieran violencia obstétrica, que es toda conducta, acción u omisión realizada por personal de la salud que afecte el cuerpo y los procesos reproductivos de las mujeres, expresada en un trato deshumanizado. OBJETIVO: Conocer el nivel de percepción de parto humanizado en las pacientes en periodo de puerperio en el servicio de ginecoobstetricia del Hospital General de Zona No. 1 del Instituto Mexicano del Seguro Social. MATERIAL Y MÉTODOS: Estudio observacional en 190 pacientes en -puerperio inmediato. Se midieron variables demográficas y se -analizó el nivel de percepción de parto humanizado (inadecuado: 18-32 puntos; regular: 35-53; adecuado: 54-72). Se utilizaron estadística descriptiva y medidas de asociación. Se recabó el consentimiento informado por escrito de las participantes y fue autorizado con el número de registro R-2018-301-020. RESULTADOS: La percepción global de parto humanizado fue inadecuada en el 56.8%, regular en el 34.7% y adecuada en el 8.4%. CONCLUSIÓN: La percepción de parto humanizado en las pacientes que están en puerperio inmediato en nuestro hospital es inadecuada, ya que no se les proporcionaron la orientación adecuada, la información sobre el manejo del dolor, la elección de la posición del trabajo de parto ni la posibilidad de que un acompañante estuviera presente durante el proceso.

Translational Molecular Ecology in practice: Linking DNA-based methods to actionable marine environmental management.

Molecular-based approaches can provide timely biodiversity assessments, showing an immense potential to facilitate decision-making in marine environmental management. However, the uptake of molecular data into environmental policy remains minimal. Here, we showcase a selection of local to global scale studies applying molecular-based methodologies for environmental management at various stages of implementation. Drawing upon lessons learned from these case-studies, we provide a roadmap to facilitate applications of DNA-based methods to marine policies and to overcome the existing challenges. The main impediment identified is the need for standardized protocols to guarantee data comparison across spatial and temporal scales. Adoption of Translational Molecular Ecology - the sustained collaboration between molecular ecologists and stakeholders, will enhance consensus with regards to the objectives, methods, and outcomes of environmental management projects. Establishing a sustained dialogue among stakeholders is key to accelerating the adoption of molecular-based approaches for marine monitoring and assessment.

In silico molecular engineering for a targeted replacement in a tumor-homing peptide.

A new amino acid has been designed as a replacement for arginine (Arg, R) to protect the tumor-homing pentapeptide CREKA (Cys-Arg-Glu-Lys-Ala) from proteases. This amino acid, denoted (Pro)hArg, is characterized by a proline skeleton bearing a specifically oriented guanidinium side chain. This residue combines the ability of Pro to induce turn-like conformations with the Arg side-chain functionality. The conformational profile of the CREKA analogue incorporating this Arg substitute has been investigated by a combination of simulated annealing and molecular dynamics. Comparison of the results with those previously obtained for the natural CREKA shows that (Pro)hArg significantly reduces the conformational flexibility of the peptide. Although some changes are observed in the backbone...backbone and side-chain...side-chain interactions, the modified peptide exhibits a strong tendency to accommodate turn conformations centered at the (Pro)hArg residue and the overall shape of the molecule in the lowest energy conformations characterized for the natural and the modified peptides exhibit a high degree of similarity. In particular, the turn orients the backbone such that the Arg, Glu, and Lys side chains face the same side of the molecule, which is considered important for bioactivity. These results suggest that replacement of Arg by (Pro)hArg in CREKA may be useful in providing resistance against proteolytic enzymes while retaining conformational features which are essential for tumor-homing activity.

Protonation of the side group in beta- and gamma-aminated proline analogues: effects on the conformational preferences.

This work shows the influence of the side-chain protonation on the conformational properties, relative stabilities, and peptide bond isomerization of four aminoproline isomers. Thus, this research has been useful to define the rules that allow control the conformation of aminoproline with the pH. Comparison of the results obtained using density functional theory calculations for the N-acetyl-N'-methylamide derivatives of the protonated isomers, which differ in the beta- or gamma-position of the substituent and its cis or trans relative disposition, with those reported for the corresponding neutral analogues (J. Phys. Chem. B 2008, 112, 14045) has allowed us to reach the following conclusions: (i) protonation of the amino group produces a reduction of the backbone conformational flexibility and a destabilization of the cis configuration of the amide bond involving the pyrrolidine nitrogen; (ii) the planarity of the peptide bond is broken in some cases to form strong side chain...backbone interactions, which induce a very significant pyramidilization at the amide nitrogen atom; (iii) as was also detected for the neutral analogues, the formation of side chain...backbone intraresidue interactions favor the cis disposition of the substituent; and (iv) protonation of the amino side group increases the energy gaps that separate the different investigated isomers resulting in an enhancement of the destabilization of the dipeptides with the substituent attached in a trans position.

Department of Veterans Affairs Consensus: Preradiation dental treatment guidelines for patients with head and neck cancer.

Few protocols have been published for the dental management of patients with head and neck cancer to prevent complications from head and neck radiation therapy. Radiation therapy not only affects the tumor cells targeted, but also the dentition, bone, salivary gland, and oral soft tissue structures. A comprehensive dental evaluation prior to head and neck radiation therapy can help prevent many complications. The following clinical guidelines were established by a workgroup of oral health providers within the Department of Veterans Affairs. This workgroup focused on developing a set of recommendations regarding dental care prior to the initiation of head and neck radiation therapy based on the best clinical evidence and expert consensus. A systematic algorithm was developed for the evaluation including pre-exam data gathering, examination, education, and treatment, followed by maintenance and postradiation dental follow-up. This document is evidence-based, patient-centered, consistent with accepted practices of care and safety, and in accordance with applicable statutes and regulations.

Conformational preferences of beta- and gamma-aminated proline analogues.

Quantum mechanical calculations have been used to investigate how the incorporation of an amino group to the Cbeta- or Cgamma-positions of the pyrrolidine ring affects the intrinsic conformational properties of the proline. Specifically, a conformational study of the N-acetyl-N'-methylamide derivatives of four isomers of aminoproline, which differ not only in the beta- or gamma-position of the substituent but also in its cis or trans relative disposition, has been performed. To further understand the role of the intramolecular hydrogen bonds between the backbone carbonyl groups and the amino side group, a conformational study was also performed on the corresponding four analogues of (dimethylamino)proline. In addition, the effects of solvation on aminoproline and (dimethylamino)proline dipeptides have been evaluated using a self-consistent reaction field model, and considering four different solvents (carbon tetrachloride, chloroform, methanol and water). Results indicate that the incorporation of the amino substituent into the pyrrolidine ring affects the conformational properties, with backbone...side chain intramolecular hydrogen bonds detected when it is incorporated in a cis relative disposition. In general, the incorporation of the amino side group tends to stabilize those structures where the peptide bond involving the pyrrolidine nitrogen is arranged in cis. The aminoproline isomer with the substituent attached to the Cgamma-position with a cis relative disposition is the most stable in the gas phase and in chloroform, methanol and water solutions. Replacement of the amino side group by the dimethylamino substituent produces significant changes in the potential energy surfaces of the four investigated (dimethylamino)proline-containing dipeptides. Thus, these changes affect not only the number of minima, which increases considerably, but also the backbone and pseudorotational preferences. In spite of these effects, comparison of the conformational preferences, i.e., the more favored conformers, calculated for different isomers of aminoproline and (dimethylamino)proline dipeptides showed a high degree of consistency for the two families of compounds.