The Impacts of the Molecular Education and Research Consortium in Undergraduate Computational Chemistry on the Careers of Women in Computational Chemistry.

The Molecular Education and Research Consortium in Undergraduate Computational Chemistry (MERCURY) has supported a diverse group of faculty and students for over 20 years by providing computational resources as well as networking opportunities and professional support. The consortium comprises 38 faculty (42% women) at 34 different institutions, who have trained nearly 900 undergraduate students, more than two-thirds of whom identify as women and one-quarter identify as students of color. MERCURY provides a model for the support necessary for faculty to achieve professional advancement and career satisfaction. The range of experiences and expertise of the consortium members provides excellent networking opportunities that allow MERCURY faculty to support each other's teaching, research, and service needs, including generating meaningful scientific advancements and outcomes with undergraduate researchers as well as being leaders at the departmental, institutional, and national levels. While all MERCURY faculty benefit from these supports, the disproportionate number of women in the consortium, relative to their representation in computational sciences generally, produces a sizable impact on advancing women in the computational sciences. In this report, the women of MERCURY share how the consortium has benefited their careers and the careers of their students.

Blood Pressure Changes in Adolescents with Preeclampsia: A Multicentre, Case-Control Study in Latin American Hospitals.

OBJECTIVE: To determine the minimum blood pressure increases that would confirm or exclude, with the greatest predictive values, hypertensive disorders of pregnancy (HDP) in pregnant adolescents after 24 weeks gestation. METHODS: We conducted a case-control study of pregnant women aged ≤19 years with and without HDP. Using systolic and diastolic blood pressure increases, a predictive analysis was performed, and the area under the curve was calculated. RESULTS: The cases and controls had systolic blood pressure increases of 45.3 ± 17.5 mm Hg and 6.4 ± 7.9 mm Hg, respectively (P = 0.001) and diastolic blood pressure increases of 30.8 ± 11.7 mm Hg and 3.5 ± 5.7 mm Hg, respectively (P = 0.001). Systolic and diastolic increases of ≥20 mm Hg showed the greatest sensitivity and specificity. A combined analysis showed that an increase of ≥20 mm Hg had a greater positive likelihood ratio of 35.4 (95% CI 22.4-55.9) and negative likelihood ratio of 0.10 (95% CI 0.07-0.13), with an area under the curve of 0.98 (95% CI 0.96-0.99). CONCLUSIONS: Systolic and diastolic blood pressure increases of ≥20 mm Hg must be considered in the diagnostic criteria for preeclampsia and gestational hypertension among pregnant adolescents past 24 weeks gestation.

A small molecule directly inhibits the p53 transactivation domain from binding to replication protein A.

Replication protein A (RPA), essential for DNA replication, repair and DNA damage signalling, possesses six ssDNA-binding domains (DBDs), including DBD-F on the N-terminus of the largest subunit, RPA70. This domain functions as a binding site for p53 and other DNA damage and repair proteins that contain amphipathic alpha helical domains. Here, we demonstrate direct binding of both ssDNA and the transactivation domain 2 of p53 (p53TAD2) to DBD-F, as well as DBD-F-directed dsDNA strand separation by RPA, all of which are inhibited by fumaropimaric acid (FPA). FPA binds directly to RPA, resulting in a conformational shift as determined through quenching of intrinsic tryptophan fluorescence in full length RPA. Structural analogues of FPA provide insight on chemical properties that are required for inhibition. Finally, we confirm the inability of RPA possessing R41E and R43E mutations to bind to p53, destabilize dsDNA and quench tryptophan fluorescence by FPA, suggesting that protein binding, DNA modulation and inhibitor binding all occur within the same site on DBD-F. The disruption of p53-RPA interactions by FPA may disturb the regulatory functions of p53 and RPA, thereby inhibiting cellular pathways that control the cell cycle and maintain the integrity of the human genome.

Characterization of suicidal behavior in Coquimbo, Chile, between 2018 and 2020. / Caracterización de la conducta suicida en población general de la Región de Coquimbo (Chile) entre 2018 y 2020.

Introduction: Suicidal behavior is a public health problem worldwide. The World Health Organization estimated 700 000 deaths for the year 2021. Objective: This study aimed to estimate the prevalence of suicidal behavior and describe its related factors in the Coquimbo Region, Chile, between 2018 and 2020. Methods: 2190 suicide attempt notifications from the regional epidemiological surveillance system were analyzed, corresponding to 1781 people, along with 217 reports from the Forensic Medical Service of people who died by suicide. Results: The overall suicide rate for the region during that period was 9.79 deaths per 100 000 inhabitants. The 2018 rates were standardized according to available information, with direct methods for the regional rate (9.55 per 100 000 inhabitants) and indirect methods for the communes. Rural communes presented higher rates than urban ones. Women showed a higher risk of attempts (OR 1.28; 95% CI 1.23 to 1.33) and a lower risk of suicide compared to men (0.086; 0.06 to 0.13). Young people had a higher risk of suicide attempts and a lower risk of suicide compared to older people. The increased suicide rates in older people (70 to 79 years) during 2020 are noteworthy. Basic education level is a risk variable for suicide (2.21; from 1.15 to 4.23), compared to having higher education. Previous suicide attempts and psychiatric pathology are risk factors. Conclusions: Suicide prevalence and related factors are similar to those reported in other studies and national reports, highlighting rurality and higher risk in older male adults. In contrast to suicides, attempts are more frequent in women and young people. A history of mental health problems, previous attempts, and family violence are risk factors for both outcomes. Knowing the patterns of suicidal behavior in the population is fundamental for its prevention.

Introducción: La conducta suicida es un problema de salud pública mundial. La Organización Mundial de la Salud estimó en 700 000 los fallecimientos por suicidio para el año 2021. Objetivo: El propósito fue estimar la prevalencia de la conducta suicida y describir sus factores relacionados en la Región de Coquimbo, Chile, entre los años 2018 y 2020. Métodos: Se analizaron 2190 notificaciones por intentos suicidas del sistema de vigilancia epidemiológica regional, que correspondieron a 1781 personas; junto con 217 informes de personas fallecidas por suicidio del Servicio Médico Legal. Resultados: La tasa global de suicidio para la región en el período fue de 9,79 fallecimientos por 100 000 habitantes. Se estandarizaron las tasas del año 2018 según la información disponible, con método directo para la tasa regional (9,55 por 100 000 habitantes) e indirecto para las comunas. Las comunas rurales presentaron mayores tasas que las urbanas. Las mujeres mostraron mayor riesgo de intentos (: 1,28; intervalo de confianza 95%: de 1,23 a 1,33) y menor riesgo de suicidio (0,086; de 0,06 a 0,13) que los hombres. Las personas jóvenes presentaron mayor riesgo de intentos y menor riesgo de suicidio, comparado con personas mayores. Destaca el aumento de la tasa de suicidio en personas mayores (de 70 a 79 años) durante el año 2020. El nivel educacional básico es una variable de riesgo para suicidio (2,21; de 1,15 a 4,23), comparado con educación universitaria. Los intentos de suicidio previos y patología psiquiátrica son factores de riesgo. Conclusiones: La prevalencia de suicidio y los factores relacionados son similares a lo reportado en otros estudios e informes nacionales, destacando la ruralidad y mayor riesgo en varones de edad adulta avanzada. A diferencia de los suicidios, los intentos son más frecuentes en mujeres y personas jóvenes. Antecedentes de problemas de salud mental, intentos previos y violencia en la familia son factores de riesgo para ambas conductas. Conocer el comportamiento de la conducta suicida en la población es fundamental para su prevención.

Human gelatin thrombin matrix with rifampin for the treatment of prosthetic vascular graft infections.

We aim to describe and report on a novel graft preservation technique using a human gelatin thrombin matrix with rifampin for the treatment of vascular graft infections. Eight patients with vascular graft infections were included, one with bilateral infections, for a total of nine cases from January 2016 through June 2021. All the patients underwent wound exploration and placement of human gelatin thrombin matrix with rifampin. No deaths or allergic reactions had been reported at the 30-day follow-up, with only one major amputation. The graft and limb salvage rates were 77.8% at the 1-year follow-up. The mean time to a major amputation was 122 days, and the mean time to graft excision was 30 days.

Sexually transmitted diseases during pregnancy in Louisiana, 2007-2009: high-risk populations and adverse newborn outcomes.

BACKGROUND: The aims of the study were to determine the prevalence of sexually transmitted diseases during pregnancy (STDs/P) in Louisiana, the association of maternal characteristics with STDs/P, and the association of STDs/P with low birth weight and preterm birth. METHODS: STDs surveillance data from 2006-2009 were linked with 2007-2009 birth certificate data. The linked data were used for analyses. The data were limited to infections of chlamydia, gonorrhea, and syphilis during pregnancy. Logistic regression was applied to evaluate associations. RESULTS: The prevalence of chlamydia, gonorrhea, and syphilis during pregnancy was 5.5%, 1.6%, and 0.3%, respectively, among women who had a live birth between 2007 and 2009. Maternal race, ethnicity, age, education, marital status, and Medicaid paid for delivery were associated with STDs/P (p-value < .05). Only infection with gonorrhea during pregnancy was associated with preterm birth [adjusted OR: 1.20 (CI95%: 1.08-1.33)]. CONCLUSIONS: The prevalence of STDs/P in Louisiana remains high. Low-educated, young, black, single, and economically disadvantaged mothers were at high risk for STDs during pregnancy. Women diagnosed with gonorrhea during pregnancy were more likely to experience preterm birth.

Insight into the conserved structural dynamics of the C-terminus of mammal PrPC identifies structural core and possible structural role of pharmacological chaperones.

Misfolding of the prion protein is central to prion disease aetiology. Although understanding the dynamics of the native fold helps to decipher the conformational conversion mechanism, a complete depiction of distal but coupled prion protein sites common across species is lacking. To fill this gap, we used normal mode analysis and network analysis to examine a collection of prion protein structures deposited on the protein data bank. Our study identified a core of conserved residues that sustains the connectivity across the C-terminus of the prion protein. We propose how a well-characterized pharmacological chaperone may stabilize the fold. Also, we provide insight into the effect on the native fold of initial misfolding pathways identified by others using kinetics studies.

Protein-lipid interactions and protein anchoring modulate the modes of association of the globular domain of the Prion protein and Doppel protein to model membrane patches.

The Prion protein is the molecular hallmark of the incurable prion diseases affecting mammals, including humans. The protein-only hypothesis states that the misfolding, accumulation, and deposition of the Prion protein play a critical role in toxicity. The cellular Prion protein (PrPC) anchors to the extracellular leaflet of the plasma membrane and prefers cholesterol- and sphingomyelin-rich membrane domains. Conformational Prion protein conversion into the pathological isoform happens on the cell surface. In vitro and in vivo experiments indicate that Prion protein misfolding, aggregation, and toxicity are sensitive to the lipid composition of plasma membranes and vesicles. A picture of the underlying biophysical driving forces that explain the effect of Prion protein - lipid interactions in physiological conditions is needed to develop a structural model of Prion protein conformational conversion. To this end, we use molecular dynamics simulations that mimic the interactions between the globular domain of PrPC anchored to model membrane patches. In addition, we also simulate the Doppel protein anchored to such membrane patches. The Doppel protein is the closest in the phylogenetic tree to PrPC, localizes in an extracellular milieu similar to that of PrPC, and exhibits a similar topology to PrPC even if the amino acid sequence is only 25% identical. Our simulations show that specific protein-lipid interactions and conformational constraints imposed by GPI anchoring together favor specific binding sites in globular PrPC but not in Doppel. Interestingly, the binding sites we found in PrPC correspond to prion protein loops, which are critical in aggregation and prion disease transmission barrier (ß2-α2 loop) and in initial spontaneous misfolding (α2-α3 loop). We also found that the membrane re-arranges locally to accommodate protein residues inserted in the membrane surface as a response to protein binding.

[Surgical management of primary spontaneous pneumothorax. A national survey of the Emerging Thoracic Surgery Group of the Spanish Society of Pneumology and Thoracic Surgery (SEPAR)]. / Manejo quirúrgico del neumotórax espontáneo primario. Encuesta nacional del Grupo Emergente de Cirugía Torácica de la Sociedad Española de Neumología y Cirugía Torácica (SEPAR).

Introduction: In February 2022, the Emerging Thoracic Surgery Group of the Spanish Society of Pneumology and Thoracic Surgery initiated a multicenter study on the surgical management of primary spontaneous pneumothorax (PSP). As a preliminary step, this survey was developed with the aim of finding out the current situation in our country to specify and direct this project. Method: A descriptive study was carried out based on the results of this survey launched through the Google Docs® platform. The survey was sent to all active national thoracic surgeons, a total of 319. It consisted of 20 questions including demographic, surgical and follow-up data. Results: We obtained 124 responses (39% of all specialists and doctors in training in the national territory). The most consistent indications were: homolateral recurrence for 124 (100%), lack of resolution of the episode for 120 (96.7%), risk professions for 104 (84%) and bilateral pneumothorax for 93 (75%). The approach of choice for 100% of respondents was videothoracoscopy. Of these, 96 contemplated pulmonary resection of obvious lesions (77%). Regarding the pleurodesis technique, pleural abrasion was the technique most used by 70 respondents (56.7%) while 49 (40%) performed chemical pleurodesis with talc either alone or in combination with mechanical pleurodesis. Conclusions: While there is some consistency in some aspects of surgical management of PSP, this survey makes evident the variability in pleurodesis techniques applied among surgeons in our country.

Cellular prion protein gene polymorphisms linked to differential scrapie susceptibility correlate with distinct residue connectivity between secondary structure elements.

The conformational conversion of the cellular prion protein (PrPC) to the misfolded and aggregated isoform, termed scrapie prion protein (PrPSc), is key to the development of a group of neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs). Although the conversion mechanism is not fully understood, the role of gene polymorphisms in varying susceptibilities to prion diseases is well established. In ovine, specific gene polymorphisms in PrPC alter prion disease susceptibility: the Valine136-Glutamine171 variant (Susceptible structure) displays high susceptibility to classical scrapie while the Alanine136-Arginine171 variant (Resistant structure) displays reduced susceptibility. The opposite trend has been reported in atypical scrapie. Despite the differentiation between classical and atypical scrapie, a complete understanding of the effect of polymorphisms on the structural dynamics of PrPC is lacking. From our structural bioinformatics study, we propose that polymorphisms locally modulate the network of residue interactions in the globular C-terminus of the ovine recombinant prion protein while maintaining the overall fold. Although the two variants we examined exhibit a densely connected group of residues that includes both ß-sheets, the ß2-α2 loop and the N-terminus of α-helix 2, only in the Resistant structure do most residues of α-helix 2 belong to this group. We identify the structural role of Valine136Alanine and Glutamine171Arginine: modulation of residue interaction networks that affect the connectivity between α-helix 2 and α-helix 3. We propose blocking interactions of residue 171 as a potential target for the design of therapeutics to prevent efficient PrPC misfolding. We discuss our results in the context of initial PrPC conversion and extrapolate to recently proposed PrPSc structures.Communicated by Ramaswamy H. Sarma.

Simultaneous rupture of two renal artery aneurysms in a patient with tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is an autosomal dominant multisystem neurocutaneous genetic condition. It is characterized by TSC-associated neuropsychiatric disorders, epilepsy, tumors, and angiomyolipoma in multiple organs, such as the skin, lungs, and kidneys. TSC is also associated with the development of aneurysms of the medium and large arteries, including the renal arteries. This condition will usually be diagnosed early in life, and active surveillance is required of tumor and aneurysm growth to prevent life-threatening events. We have presented the case of a 41-year-old patient with TSC that had not been previously diagnosed. The patient had presented with retroperitoneal hematoma secondary to the rupture of two left renal artery branch aneurysms that had likely developed within the angiomyolipoma.

Oligomers of the prion protein fragment 106-126 are likely assembled from beta-hairpins in solution, and methionine oxidation inhibits assembly without altering the peptide's monomeric conformation.

A portion of the prion protein, PrP106-126, is highly conserved among various species and is thought to be one of the key domains involving amyloid formation of the protein. We used ion mobility spectrometry-mass spectrometry (IMS-MS) in conjunction with replica exchange molecular dynamics (REMD) to examine the monomeric and oligomeric structures of normal PrP106-126 and two nonaggregating forms of the peptide, an oxidized form in which both methionine residues are oxidized to methionine sulfoxide and a control peptide consisting of the same amino acids as PrP106-126 in a scrambled sequence. Our ion mobility and simulation data indicate the presence of a population of beta-hairpin monomers for the normal and oxidized peptides. This is supported by our CD data indicating that a monomer solution of the normal peptide contains approximately 46% beta-sheet and approximately 23% beta-turn content, in excellent agreement with our REMD simulations. Oligomerization was seen by IMS-MS for the normal peptide only, not the oxidized peptide or the control sequence. Both our IMS-MS and CD data suggest that this oligomerization results from the association of ordered beta-hairpin monomers rather than disordered monomers. Structural analysis shows that the normal and oxidized peptides have similar secondary and tertiary structural properties, suggesting that the inhibition of aggregation caused by methionine oxidation stems from mediating interpeptide interactions rather than by altering the peptide's monomeric conformation. In contrast, an increase in alpha-helical and random coil structural components relative to the normal peptide might be responsible for the lack of observed aggregation of the control peptide.

The effect of surface tethering on the folding of the src-SH3 protein domain.

The effect of surface tethering on the folding mechanism of the src-SH3 protein domain was investigated using a coarse-grained Go-type protein model. The protein was tethered at various locations along the protein chain and the thermodynamics and kinetics of folding were studied using replica exchange and constant temperature Langevin dynamics. Our simulations reveal that tethering in a structured part of the transition state can dramatically alter the folding mechanism, while tethering in an unstructured part leaves the folding mechanism unaltered as compared to bulk folding. Interestingly, there is only modest correlation between the tethering effect on the folding mechanism and its effect on thermodynamic stability and folding rates. We suggest locations on the protein at which tethering could be performed in single-molecule experiments so as to leave the folding mechanism unaltered from the bulk.

Comparison of combined spinal and general anesthesia block and combined epidural and general anesthesia block in laparoscopic cholecystectomy.

OBJECTIVE: Combined spinal and general anesthesia block (CSGAB) and combined epidural and general anesthesia block (CEGAB) in laparoscopic cholecystectomy were compared. MATERIAL AND METHODS: Forty patients were randomly selected (ASA physical status I-II) to receive sevoflurane plus 10 to 15 mg of bupivacaine weighed at 0.5% and 20 microg of fentanyl (CSGAB) or sevoflurane plus 150 mg of ropivacaine and 1 microg/kg of fentanyl (CEGAB). Blood pressure, heart rate, oxygen and carbon dioxide saturation, drug doses and sevoflurane MAC (minimum alveolar concentration) were evaluated during surgery. Anesthesia recovery time and pain intensity and duration were evaluated during the first two postoperative hours. Frequency of incisional or referred pain, dyspnea, headache, cramping, nausea and vomiting were evaluated 24 hours after surgery. Statistical analysis was carried out using the Chi-square test and Student t test. Relative risk, absolute risk reduction and number needed to treat (NNT) for adverse reactions were determined. RESULTS: Systolic and diastolic arterial pressures posterior to semi-Fowler's position were lower in the CSGAB group than in the CEGAB group. (94 +/- 16 vs. 110 +/- 18 mmHg; p < 0.01 and 59 +/- 8 vs. 69 +/- 12, mmHg; p < 0.01, respectively). Anesthesia recovery time (32 +/- 17 vs. 61 +/- 29 minutes; p < 0.01) and pain duration (26 +/- 42 vs. 83 +/- 46 minutes; p < 0.01) were shorter in the CSGAB group. NNT was 8 for postoperative pain, 8 for nausea, and 95 for vomiting. CONCLUSIONS: CSGAB was more efficacious for rapid anesthesia recovery and had a shorter post-operative pain duration than CEGAB.

Caracterización de la conducta suicida en población general de la Región de Coquimbo (Chile) entre 2018 y 2020 / Characterization of suicidal behavior in Coquimbo, Chile, between 2018 and 2020

Introducción La conducta suicida es un problema de salud pública mundial. La Organización Mundial de la Salud estimó en 700 000 los fallecimientos por suicidio para el año 2021. Objetivo El propósito fue estimar la prevalencia de la conducta suicida y describir sus factores relacionados en la Región de Coquimbo, Chile, entre los años 2018 y 2020. Métodos Se analizaron 2190 notificaciones por intentos suicidas del sistema de vigilancia epidemiológica regional, que correspondieron a 1781 personas; junto con 217 informes de personas fallecidas por suicidio del Servicio Médico Legal. Resultados La tasa global de suicidio para la región en el período fue de 9,79 fallecimientos por 100 000 habitantes. Se estandarizaron las tasas del año 2018 según la información disponible, con método directo para la tasa regional (9,55 por 100 000 habitantes) e indirecto para las comunas. Las comunas rurales presentaron mayores tasas que las urbanas. Las mujeres mostraron mayor riesgo de intentos (: 1,28; intervalo de confianza 95%: de 1,23 a 1,33) y menor riesgo de suicidio (0,086; de 0,06 a 0,13) que los hombres. Las personas jóvenes presentaron mayor riesgo de intentos y menor riesgo de suicidio, comparado con personas mayores. Destaca el aumento de la tasa de suicidio en personas mayores (de 70 a 79 años) durante el año 2020. El nivel educacional básico es una variable de riesgo para suicidio (2,21; de 1,15 a 4,23), comparado con educación universitaria. Los intentos de suicidio previos y patología psiquiátrica son factores de riesgo. Conclusiones La prevalencia de suicidio y los factores relacionados son similares a lo reportado en otros estudios e informes nacionales, destacando la ruralidad y mayor riesgo en varones de edad adulta avanzada. A diferencia de los suicidios, los intentos son más frecuentes en mujeres y personas jóvenes. Antecedentes de problemas de salud mental, intentos previos y violencia en la familia son factores de riesgo para ambas conductas. Conocer el comportamiento de la conducta suicida en la población es fundamental para su prevención.

Introduction Suicidal behavior is a public health problem worldwide. The World Health Organization estimated 700 000 deaths for the year 2021. Objective This study aimed to estimate the prevalence of suicidal behavior and describe its related factors in the Coquimbo Region, Chile, between 2018 and 2020. Methods 2190 suicide attempt notifications from the regional epidemiological surveillance system were analyzed, corresponding to 1781 people, along with 217 reports from the Forensic Medical Service of people who died by suicide. Results The overall suicide rate for the region during that period was 9.79 deaths per 100 000 inhabitants. The 2018 rates were standardized according to available information, with direct methods for the regional rate (9.55 per 100 000 inhabitants) and indirect methods for the communes. Rural communes presented higher rates than urban ones. Women showed a higher risk of attempts (OR 1.28; 95% CI 1.23 to 1.33) and a lower risk of suicide compared to men (0.086; 0.06 to 0.13). Young people had a higher risk of suicide attempts and a lower risk of suicide compared to older people. The increased suicide rates in older people (70 to 79 years) during 2020 are noteworthy. Basic education level is a risk variable for suicide (2.21; from 1.15 to 4.23), compared to having higher education. Previous suicide attempts and psychiatric pathology are risk factors. Conclusions Suicide prevalence and related factors are similar to those reported in other studies and national reports, highlighting rurality and higher risk in older male adults. In contrast to suicides, attempts are more frequent in women and young people. A history of mental health problems, previous attempts, and family violence are risk factors for both outcomes. Knowing the patterns of suicidal behavior in the population is fundamental for its prevention.

Role of water in mediating the assembly of Alzheimer amyloid-beta Abeta16-22 protofilaments.

The role of water in promoting the formation of protofilaments (the basic building blocks of amyloid fibrils) is investigated using fully atomic molecular dynamics simulations. Our model protofilament consists of two parallel beta-sheets of Alzheimer Amyloid-beta 16-22 peptides (Ac-K(16)-L(17)-V(18)-F(19)-F(20)-A(21)-E(22)-NH2). Each sheet presents a distinct hydrophobic and hydrophilic face and together self-assemble to a stable protofilament with a core consisting of purely hydrophobic residues (L(17), F(19), A(21)), with the two charged residues (K(16), E(22)) pointing to the solvent. Our simulations reveal a subtle interplay between a water mediated assembly and one driven by favorable energetic interactions between specific residues forming the interior of the protofilament. A dewetting transition, in which water expulsion precedes hydrophobic collapse, is observed for some, but not all molecular dynamics trajectories. In the trajectories in which no dewetting is observed, water expulsion and hydrophobic collapse occur simultaneously, with protofilament assembly driven by direct interactions between the hydrophobic side chains of the peptides (particularly between F-F residues). For those same trajectories, a small increase in the temperature of the simulation (on the order of 20 K) or a modest reduction in the peptide-water van der Waals attraction (on the order of 10%) is sufficient to induce a dewetting transition, suggesting that the existence of a dewetting transition in simulation might be sensitive to the details of the force field parametrization.

Factors affecting the number and type of student research products for chemistry and physics students at primarily undergraduate institutions: A case study.

For undergraduate students, involvement in authentic research represents scholarship that is consistent with disciplinary quality standards and provides an integrative learning experience. In conjunction with performing research, the communication of the results via presentations or publications is a measure of the level of scientific engagement. The empirical study presented here uses generalized linear mixed models with hierarchical bootstrapping to examine the factors that impact the means of dissemination of undergraduate research results. Focusing on the research experiences in physics and chemistry of undergraduates at four Primarily Undergraduate Institutions (PUIs) from 2004-2013, statistical analysis indicates that the gender of the student does not impact the number and type of research products. However, in chemistry, the rank of the faculty advisor and the venue of the presentation do impact the number of research products by undergraduate student, whereas in physics, gender match between student and advisor has an effect on the number of undergraduate research products. This study provides a baseline for future studies of discipline-based bibliometrics and factors that affect the number of research products of undergraduate students.

Peptide self-assembly at the nanoscale: a challenging target for computational and experimental biotechnology.

Self-assembly at the nanoscale is becoming increasingly important for the fabrication of novel supramolecular structures, with applications in the fields of nanobiotechnology and nanomedicine. Peptides represent the most favorable building blocks for the design and synthesis of nanostructures because they offer a great diversity of chemical and physical properties, they can be synthesized in large amounts, and can be modified and decorated with functional elements, which can be used in diverse applications. In this article, we review some of the most recent experimental advances in the use of nanoscale self-assembled peptide structures and the theoretical efforts aimed at understanding the microscopic determinants of their formation, stability and conformational properties. The combination of experimental observations and theoretical advances will be fundamental to fully realizing the biotechnological potential of peptide self-organization.

Characterization of the stereochemical selectivity of beta-hairpin formation by molecular dynamics simulations.

The stability of secondary structure motifs found in proteins is influenced by the choice of the configuration of the chiral centers present in the amino acid residues (i.e., D vs L). Experimental studies showed that the structural properties of the tetrapeptide (L)V(L)P(L)A(L)L (all-L) are drastically altered upon mutating the L-proline and the L-alanine by their d-enantiomers [J. Am. Chem. Soc. 1996, 118, 6975]. The all-L diastereomer is unstructured, experiencing little or no beta-hairpin formation, while the (L)V(D)P(D)A(L)L peptide exhibits a substantial population of beta-hairpin conformation. In this study, we perform molecular dynamics simulations to investigate the folding propensity of these two model peptides. The results confirm the experimental findings, namely, that the presence of d-amino acids in the loop region strongly induces beta-hairpin formation (a population increase from about 1.5% to 50% is observed). The major factor determining the different behavior is found to be the large difference in energy between the two diastereomers, approximately 22 kJ/mol, when they adopt a beta-hairpin structure. The higher energy observed for the all-L peptide is a consequence of none-ideal hydrogen bond formation and of steric repulsions. The results suggest that selective incorporation of D-amino acids in proteins can be used to enhance certain secondary structure elements. The kinetic behavior of the folding process observed in the simulations is also investigated. We find that the decay rate of the folded structure fits to a biexponential function, suggesting that the folding/unfolding process of a beta-hairpin is governed by two different mechanisms.

Levamisol en el tratamiento del síndrome nefrótico / Levamisole in the treatment of nephrotic síndrome

No disponible