Breakfast consumption, saturated fat intake, and body mass index among medical and non-medical students: a cross-sectional analysis.

Changes in dietary patterns and body weight have become a focus of research in undergraduate students. This study compared breakfast consumption, intake of foods high in saturated fat, and BMI between medical and non-medical students. A comparative cross-sectional study was conducted in 4,561 Peruvian university students, of whom 1,464 (32.1%) were from the medical field and 3,097 (67.9%) from the non-medical field. We compared the frequency of breakfast consumption (categorized as regular: 6 to 7 days/week; occasional: 3 to 5 days/week; and rarely or never: 0 to 2 days/week) and the frequency of consumption of foods high in saturated fat. We created simple and multiple linear and Poisson regression models with robust variance to evaluate the association of the mentioned variables with academic fields. Non-medical students (Adjusted Prevalence Ratio [PR] = 0.92, 95% CI 0.86-0.99; p = 0.008) were less likely to eat breakfast regularly compared to medical students. Likewise, consumption of foods high in saturated fats was higher in non-medical students (B = 1.47, 95% CI 0.91-2.04; p < 0.001) compared to medical students. Similarly, the mean BMI of these students was significantly higher than that of medical students (B = 0.33, 95% CI 0.12-0.53; p = 0.002). Although medical students reported relatively healthy eating habits and a lower BMI, there is a widespread need to promote improved diet and lifestyle among the entire university population to reduce the risks of communicable diseases and improve quality of life.

Job Satisfaction in Remote Work: The Role of Positive Spillover from Work to Family and Work-Life Balance.

The objective of this research is to propose and validate a theoretical model that explains job satisfaction in remote work influenced by family-supportive supervisory behaviors (FSSBs) and, in addition, to evaluate the mediating role of work-to-family positive spillover (WFPS) and work-life balance (WLB) in this influence. A non-experimental cross-sectional study was conducted using a self-administered survey to a sample of 396 teleworkers in Lima, Peru. The hypothesized model was analyzed using PLS-SEM based structural equation modeling. The results show that FSSB has a direct effect on both job satisfaction in remote work and WFPS and WLB. In addition, it shows that WFPS and WLB have positive effects on job satisfaction in remote work. Also, the results show that WFPS and WLB have a mediating role in the influence of FSSB on job satisfaction in remote work. In conclusion, this study highlights the importance of supervisor behavior, positive work-to-family spillover, and work-life balance in remote workers' job satisfaction. It is suggested that companies adopt policies and practices that encourage work-life balance as well as a favorable supervisory environment.

Mutational Analysis of Protein Folding Transition States: Phi Values.

The analysis of protein folding reactions by monitoring the kinetic effects of specifically designed single-point mutations, the so-termed phi-value analysis, has been a favorite technique to experimentally probe the mechanisms of protein folding. The idea behind phi-value analysis is that the effects that mutations have on the folding and unfolding rate constants report on the energetic/structural features of the folding transition state ensemble (TSE), which is the highest point in the free energy surface connecting the native and unfolded states, and thus the rate limiting step that ultimately defines the folding mechanism. For single-domain, two-state folding proteins, the general procedure to perform the phi-value analysis of protein folding is relatively simple to implement in the lab. Once the mutations have been produced and purified, the researcher needs to follow a few specific guidelines to perform the experiments and to analyze the data so produced. In this chapter, a step-by-step description of how to measure and interpret the effects induced by site-directed mutations on the folding and unfolding rate constants of a protein of interest is provided. Some possible solutions to the most typical problems that arise when performing phi-value analysis in the lab are also provided.

Association between orthodontic treatment and the occurrence of temporomandibular disorders: A systematic review and meta-analysis.

Background: Temporomandibular disorders (TMD) are related to a series of clinical manifestations that appear in the form of pain. Currently, there is controversy about the appearance of TMDs after orthodontic treatment. Therefore, the objective of the present study was to determine the association between orthodontic treatment and the occurrence of Temporomandibular Disorders (TMD). Material and Methods: A bibliographic search was carried out until April 2022, in the following electronic databases: Pubmed/Medline, Scopus, Scielo, Google Scholar and Web of Science. We included studies that were case-control and cohort studies, dealing with the association between orthodontic treatment and TMD, in English and Spanish, and with no time limit. The Newcastle-Ottawa scale was used to assess risk in the included studies. In addition, RevMan 5.3 was considered for meta-analysis, using as a measure the ODDS ratio in a random-effects model with a 95% confidence interval. Results: The preliminary search yielded a total of 686 articles, discarding those that did not meet the selection criteria, leaving only 6 articles. These studies reported that there is a significant association between orthodontic treatment and the occurrence of TMD, equivalent to an ODDS ratio of 1.84 with a confidence interval of 1.19-2.83. Conclusions: It is concluded that there is an association between orthodontic treatment and the occurrence of TMD, therefore, a person undergoing orthodontic treatment is up to 1.84 times more likely to develop TMD. Key words:Orthodontic treatment, temporomandibular disorders, orthodontics, cases and controls, cohorts, review, Meta-Analysis.

Lessons about Protein Folding and Binding from Archetypal Folds.

The function of proteins as biological nanomachines relies on their ability to fold into complex 3D structures, bind selectively to partners, and undergo conformational changes on cue. The native functional structures, and the rates of interconversion between conformational states (folded-unfolded, bound-free), are all encoded in the physical chemistry of their amino acid sequence. However, despite extensive research over decades, this code has proven difficult to fully crack, in terms of both prediction and understanding the molecular mechanisms at play.Earlier work on single-domain proteins reported a commonality of slow rates (10-2-102 s-1) and simple behavior in both kinetic and thermodynamic unfolding experiments, which suggested the process was all-or-none and thereby analogous to a chemical reaction (e.g., A ⇄ B). In the absence of a first-principles pre-exponential factor for protein (un)folding dynamics, the rates could only be interpreted in relative terms, e.g., the changes induced by mutation, and hence, neither the height of nor the entropic contribution to the free energy barriers was known. The rates were also many orders of magnitude too slow for direct atomistic simulations, and the computational focus was on predicting rate changes induced by mutation via coarse grained simulations. However, even the effects of mutation proved to be strikingly homogeneous with all experimental data clustering at ∼1/3 of the free energy perturbation recovered on folding and ∼2/3 on unfolding.The implementation of ultrafast kinetic methods turned the field upside down because they allowed researchers to measure the time scales of elementary (un)folding motions, which set the pre-exponential factor for protein conformational transitions at ∼1 µs. In parallel, we and others set out to investigate the simplest possible protein structures capable of autonomous folding, which we defined as archetypal folds. The rationale was to recapitulate the hierarchical organization of protein structure, starting from the bottom up. The study of fold archetypes ended up opening new research avenues in protein (un)folding, but also making unexpected connections with the folding upon binding of intrinsically disordered proteins and suggesting their functioning as conformational rheostats.This Account describes our work on the kinetic, thermodynamic, mechanistic, and functional analysis of fold archetypes. We first discuss the kinetic studies, emphasizing their impact on our understanding of (un)folding rates, of barrierless (downhill) folding, and as benchmarks for atomistic simulations. We continue with the thermodynamic analysis, introducing the differential scanning calorimetry, multiprobe, and NMR approaches that we developed to dissect their gradual, minimally cooperative (un)folding transitions and to probe the underlying mechanisms with unprecedented detail. The last two sections cover single-molecule analyses and some recent, mostly computational, results on the exploration of possible biological and technological roles for the gradual conformational transitions of fold archetypes.

Role of neighboring FMN side chains in the modulation of flavin reduction potentials and in the energetics of the FMN:apoprotein interaction in Anabaena flavodoxin.

Flavodoxins (Flds) are electron transfer proteins that carry a noncovalently bound flavin mononucleotide molecule (FMN) as a redox active center. A distinguishing feature of these flavoproteins is the dramatic change in the E(sq/rd) reduction potential of the FMN upon binding to the apoprotein (at pH 8.0, from -269 mV when free in solution to -438 mV in Anabaena Fld). In this study, the contribution of three neighboring FMN residues, Thr56, Asn58, and Asn97, and of three negatively charged surface residues, Glu20, Asp65, and Asp96, to modulate the redox properties of FMN upon its binding to the apoprotein has been investigated. Additionally, the role of these residues in the apoflavodoxin:FMN interaction has been analyzed. Concerning the redox potentials, the most noticeable result was obtained for the Thr56Gly mutant. In this Fld variant, the increased accessibility of FMN leads to an increase of +63 mV in the E(sq/rd) value. On the other hand, a correlation between the electrostatic environment of FMN and the E(sq/rd) has been observed. The more positive residues or the less negative residues present in the surroundings of the FMN N(1) atom, then the less negative the value for E(sq/rd). With regard to FMN binding to apoflavodoxin, breaking of hydrophobic interactions between FMN and residues 56, 58, and 97 seems to increase the K(d) values, especially in the Thr56Gly Fld. Such results suggest that the H-bond network in the FMN environment influences the FMN affinity.

The active site of pepsin is formed in the intermediate conformation dominant at mildly acidic pH.

Pepsin is an aspartic protease that acts in food digestion in the mammal stomach. An optimal pH of around 2 allows pepsin to operate in its natural acidic environment, while at neutral pH the protein is denatured. Although the pH dependence of pepsin activity has been widely investigated since the 40s, a renewed interest in this protein has been fueled by its homology to the HIV and other aspartic proteases. Recently, an inactive pepsin conformation has been identified that accumulates at mildly acidic pH, whose structure and properties are largely unknown. In this paper, we analyse the conformation of pepsin at different pHs by a combination of spectroscopic techniques, and obtain a detailed characterisation of the intermediate. Our analysis indicates that it is the dominant conformation from pH 4 to 6.5. Interestingly, its near UV circular dichroism spectrum is identical to that of the native conformation that appears at lower pH values. In addition, we show that the intermediate binds the active site inhibitor pepstatin with a strength similar to that of the native conformation. Pepsin thus adopts, in the 6.5-4.0 pH interval, a native-like although catalytically inactive conformation. The possible role of this intermediate during pepsin transportation to the stomach lumen is discussed.

Reaction of wheat genotypes to soil aluminum differential saturations

Ten wheat (Triticum aestivum) genotypes were evaluated in microplots with aluminum saturation of 0, 15, 30 and 45 percent, during 1994, in Londrina, Paraná, Brazil. The soil was a Distrofic Red Latosol (Typic Haplorthox), with 65 percent saturation of aluminum, amended with dolomitic lime. Variables evaluated included grain yield and yield components: ears.m-2, grains.ear-1 and the weight of 1000 grains. Genotypes differed in yield and yield components. Increasing aluminum saturation decreased yield, ears.m-2 and grains.ear-1, but did not alter thousand kernel weight. The genotypes reacted differently in relation to the toxic soil aluminum. Anahuac and IAPAR 29 were aluminum sensitive; OCEPAR 16, Trigo BR 18, and Trigo BR 23 were moderately sensitive; IAPAR 6, IAPAR 53, and IAPAR 60 were moderately tolerant; while IAC 5-Maringá and Trigo BR 35 were tolerant

Salt-induced stabilization of apoflavodoxin at neutral pH is mediated through cation-specific effects.

Electrostatic contributions to the conformational stability of apoflavodoxin were studied by measurement of the proton and salt-linked stability of this highly acidic protein with urea and temperature denaturation. Structure-based calculations of electrostatic Gibbs free energy were performed in parallel over a range of pH values and salt concentrations with an empirical continuum method. The stability of apoflavodoxin was higher near the isoelectric point (pH 4) than at neutral pH. This behavior was captured quantitatively by the structure-based calculations. In addition, the calculations showed that increasing salt concentration in the range of 0 to 500 mM stabilized the protein, which was confirmed experimentally. The effects of salts on stability were strongly dependent on cationic species: K(+), Na(+), Ca(2+), and Mg(2+) exerted similar effects, much different from the effect measured in the presence of the bulky choline cation. Thus cations bind weakly to the negatively charged surface of apoflavodoxin. The similar magnitude of the effects exerted by different cations indicates that their hydration shells are not disrupted significantly by interactions with the protein. Site-directed mutagenesis of selected residues and the analysis of truncation variants indicate that cation binding is not site-specific and that the cation-binding regions are located in the central region of the protein sequence. Three-state analysis of the thermal denaturation indicates that the equilibrium intermediate populated during thermal unfolding is competent to bind cations. The unusual increase in the stability of apoflavodoxin at neutral pH affected by salts is likely to be a common property among highly acidic proteins.