Dynamics-based protein network features accurately discriminate neutral and rheostat positions.

In some proteins, a unique class of nonconserved positions is characterized by their ability to generate diverse functional outcomes through single amino acid substitutions. Due to their ability to tune protein function, accurately identifying such "rheostat" positions is crucial for protein design, for understanding the impact of mutations observed in humans, and for predicting the evolution of pathogen drug resistance. However, identifying rheostat positions has been challenging, due-in part-to the absence of a clear structural relationship with binding sites. In this study, experimental data from our previous study of the Escherichia coli lactose repressor protein (LacI) was used to identify rheostat positions for which mutations tune in vivo EC50 for the allosteric ligand "IPTG." We next used the rheostat assignments to test the hypothesis that rheostat positions have unique dynamic features that will enable their identification. To that end, we integrated all-atom molecular dynamics simulations with perturbation residue response analysis. Results first revealed distinct dynamic behavior in IPTG-bound LacI compared with apo LacI, which was consistent with IPTG's role as an allosteric inducer. Next, we used a variety of dynamic features to build a classification model that discriminates experimentally characterized rheostat positions in LacI from positions with other types of substitution outcomes. In parallel, we built a second classifier model based on the 3D structural "static" network features of LacI. In comparative studies, the dynamic model better identified rheostat positions that were >8 Å from the binding site. In summary, our study provides insights into the dynamic characteristics of rheostat positions and suggests that models built on dynamic features may be useful for predicting the locations of rheostat positions in a wide range of proteins.

Feed form and perch design do not interact to production performance, gastrointestinal tract traits, behaviour and welfare of laying hens reared in enriched cages.

1. It was hypothesised that perch material and design may affect utility and maintenance energy demand in laying hens, affecting their feed form preferences and daily feed consumption. Accordingly, perch design and feed form on hen performance, gastrointestinal tract functions and some behavioural and welfare-related traits were studied in laying hens (ATAK-S) reared in enriched colony cages from 24 to 40 weeks of age.2. The experiment was a 2 × 2 factorial investigating two perch materials and design (circular steel or mushroom-shaped plastic) and feed form (mash or crumble). A total of 396 hens were randomly assigned to one of the four treatment groups with nine replicates each (11 birds per replicate).3. Except for feeding behaviour and prevalence of foot pad dermatitis at 40 weeks of age, the modification of the perch design did not have a significant effect on the traits examined. Mushroom-shaped plastic perches reduced feeding behaviour (p < 0.01) and the incidence of foot pad dermatitis at 40 weeks of age (p < 0.001).4. Performance traits were not affected by feed form. Intake, final body weight and FCR for crumble-fed laying hens were greater than those fed mash (p < 0.01).5. Hens fed mash had higher (p < 0.01) relative gizzard weights along with lower (p < 0.05) pH values, pancreatic chymotrypsin, amylase and lipase activities (p < 0.05), and duodenal absorption surface areas (p < 0.01). Ultimately, this gave higher protein digestibility (p < 0.05) compared to those receiving crumble.6. In conclusion, in enriched cage rearing systems, mashed feed was preferred over crumble to efficiently maintain productive performance. Compared to circular steel, plastic mushroom-shaped perches were associated with better footpad health and welfare.

Protein dynamics provide mechanistic insights about epistasis among common missense polymorphisms.

Sequencing of the protein coding genome has revealed many different missense mutations of human proteins and different population frequencies of corresponding haplotypes, which consist of different sets of those mutations. Here, we present evidence for pairwise intramolecular epistasis (i.e., nonadditive interactions) between many such mutations through an analysis of protein dynamics. We suggest that functional compensation for conserving protein dynamics is a likely evolutionary mechanism that maintains high-frequency mutations that are individually nonneutral but epistatically compensating within proteins. This analysis is the first of its type to look at human proteins with specific high population frequency mutations and examine the relationship between mutations that make up that observed high-frequency protein haplotype. Importantly, protein dynamics revealed a separation between high and low frequency haplotypes within a target protein cytochrome P450 2A7, with the high-frequency haplotypes showing behavior closer to the wild-type protein. Common protein haplotypes containing two mutations display dynamic compensation in which one mutation can correct for the dynamic effects of the other. We also utilize a dynamics-based metric, EpiScore, that evaluates the epistatic interactions and allows us to see dynamic compensation within many other proteins.

Dynamic coupling of residues within proteins as a mechanistic foundation of many enigmatic pathogenic missense variants.

Many pathogenic missense mutations are found in protein positions that are neither well-conserved nor fall in any known functional domains. Consequently, we lack any mechanistic underpinning of dysfunction caused by such mutations. We explored the disruption of allosteric dynamic coupling between these positions and the known functional sites as a possible mechanism for pathogenesis. In this study, we present an analysis of 591 pathogenic missense variants in 144 human enzymes that suggests that allosteric dynamic coupling of mutated positions with known active sites is a plausible biophysical mechanism and evidence of their functional importance. We illustrate this mechanism in a case study of ß-Glucocerebrosidase (GCase) in which a vast majority of 94 sites harboring Gaucher disease-associated missense variants are located some distance away from the active site. An analysis of the conformational dynamics of GCase suggests that mutations on these distal sites cause changes in the flexibility of active site residues despite their distance, indicating a dynamic communication network throughout the protein. The disruption of the long-distance dynamic coupling caused by missense mutations may provide a plausible general mechanistic explanation for biological dysfunction and disease.

Dynamic allostery highlights the evolutionary differences between the CoV-1 and CoV-2 main proteases.

The SARS-CoV-2 coronavirus has become one of the most immediate and widely studied systems since its identification and subsequent global outbreak from 2019 to 2022. In an effort to understand the biophysical changes as a result of mutations, the mechanistic details of multiple different proteins within the SARS-CoV-2 virus have been studied and compared with SARS-CoV-1. Focusing on the main protease (mPro), we explored the long-range dynamics using the Dynamic Coupling Index (DCI) to investigate the dynamic coupling between the catalytic site residues and the rest of the protein, both inter- and intrachain, for the CoV-1 and CoV-2 mPro. We found that there is significant cross-chain coupling between these active sites and specific distal residues in the CoV-2 mPro not present in CoV-1. The enhanced long-distance interactions, particularly between the two chains, suggest subsequently enhanced cooperativity for CoV-2. A further comparative analysis of the dynamic flexibility using the dynamic flexibility index (DFI) between the CoV-1 and CoV-2 mPros shows that the inhibitor binding near active sites induces change in flexibility to a distal region of the protein, opposite in behavior between the two systems; this region becomes more flexible upon inhibitor binding in CoV-1, while it becomes less flexible in the CoV-2 mPro. Upon inspection, we show that, on average, the dynamic flexibility of the sites substituted from CoV-1 to CoV-2 changes significantly less than the average calculated across all residues within the structure, indicating that the differences in behaviors between the two systems is likely the result of allosteric influence, in which the new substitutions in CoV-2 induce flexibility and dynamic changes elsewhere in the structure.

Substitutions at Nonconserved Rheostat Positions Modulate Function by Rewiring Long-Range, Dynamic Interactions.

Amino acid substitutions at nonconserved protein positions can have noncanonical and "long-distance" outcomes on protein function. Such outcomes might arise from changes in the internal protein communication network, which is often accompanied by changes in structural flexibility. To test this, we calculated flexibilities and dynamic coupling for positions in the linker region of the lactose repressor protein. This region contains nonconserved positions for which substitutions alter DNA-binding affinity. We first chose to study 11 substitutions at position 52. In computations, substitutions showed long-range effects on flexibilities of DNA-binding positions, and the degree of flexibility change correlated with experimentally measured changes in DNA binding. Substitutions also altered dynamic coupling to DNA-binding positions in a manner that captured other experimentally determined functional changes. Next, we broadened calculations to consider the dynamic coupling between 17 linker positions and the DNA-binding domain. Experimentally, these linker positions exhibited a wide range of substitution outcomes: Four conserved positions tolerated hardly any substitutions ("toggle"), ten nonconserved positions showed progressive changes from a range of substitutions ("rheostat"), and three nonconserved positions tolerated almost all substitutions ("neutral"). In computations with wild-type lactose repressor protein, the dynamic couplings between the DNA-binding domain and these linker positions showed varied degrees of asymmetry that correlated with the observed toggle/rheostat/neutral substitution outcomes. Thus, we propose that long-range and noncanonical substitutions outcomes at nonconserved positions arise from rewiring long-range communication among functionally important positions. Such calculations might enable predictions for substitution outcomes at a range of nonconserved positions.

Effect of temperature manipulation during incubation on body weight, plasma parameters, muscle histology, and expression of myogenic genes in breast muscle of embryos and broiler chickens from two commercial strains.

1. This study evaluated the effect of a higher incubation temperature on body weight, plasma profile, histology and expression of myogenin (MYOG), insulin-like growth factor-I (IGF-I) and vascular endothelial growth factor A (VEGFA) genes in breast muscle of embryos and broilers from two commercial strains.2. A total of 784 eggs from Ross 308 and Cobb 500 broiler breeder flocks were used. Half of the eggs per strain were incubated at control temperature (37.8°C), whereas the other half were exposed to heat treatment (HT) of 38.8°C between embryonic day (ED) 10 and 14, for 6 h/day. Embryos and chicks were sampled on ED 19 and at hatch. A total of 480, one-day-old chicks per strain and incubation temperature were reared up to 42 d post-hatch.3. The HT increased hatch weight of Ross chicks and 42-d body weight of broilers from both strains. Lower plasma triacylglycerol levels were measured for HT embryos and broilers on ED 19 and 42 d post-hatch, respectively. HT reduced plasma T3 levels in Ross embryos and broilers for the same periods. Hepatic TBARS concentrations were elevated by HT compared to the control incubation.4. The HT reduced breast muscle VEGFA gene expression of Cobb embryos on ED 19, whereas expression was stimulated in day-old chicks. At 42 d post-hatch, fibre area was increased by HT regardless of strain. Compared to the control incubation, HT increased the breast yield of Ross broilers and leg yield of Cobb. Ross-HT broilers had a higher pH at 24 h after slaughter and better water holding capacity than Cobb-HT broilers.5. These results suggested that HT increased body weight, fibre area, IGF-I gene expression and lowered plasma triacylglycerol levels of broiler chickens from both strains at 42 d. However, HT influenced the expression of VEGF-A and MYOG genes and meat quality differently between the broiler strains.

The Role of Rigid Residues in Modulating TEM-1 ß-Lactamase Function and Thermostability.

The relationship between protein motions (i.e., dynamics) and enzymatic function has begun to be explored in ß-lactamases as a way to advance our understanding of these proteins. In a recent study, we analyzed the dynamic profiles of TEM-1 (a ubiquitous class A ß-lactamase) and several ancestrally reconstructed homologues. A chief finding of this work was that rigid residues that were allosterically coupled to the active site appeared to have profound effects on enzyme function, even when separated from the active site by many angstroms. In the present work, our aim was to further explore the implications of protein dynamics on ß-lactamase function by altering the dynamic profile of TEM-1 using computational protein design methods. The Rosetta software suite was used to mutate amino acids surrounding either rigid residues that are highly coupled to the active site or to flexible residues with no apparent communication with the active site. Experimental characterization of ten designed proteins indicated that alteration of residues surrounding rigid, highly coupled residues, substantially affected both enzymatic activity and stability; in contrast, native-like activities and stabilities were maintained when flexible, uncoupled residues, were targeted. Our results provide additional insight into the structure-function relationship present in the TEM family of ß-lactamases. Furthermore, the integration of computational protein design methods with analyses of protein dynamics represents a general approach that could be used to extend our understanding of the relationship between dynamics and function in other enzyme classes.

Rheological fingerprinting as an effective tool to guide development of personal care formulations.

OBJECTIVE: Conventional rheological techniques in the linear viscoelastic region provide insights about the spatial configuration of the microstructural components of personal care formulations in their 'at-rest' state. However, they fail to describe the textural experience associated with large and fast deformations during daily consumer application. In this study we present a non-conventional rheological technique-large amplitude oscillatory shear (LAOS)-for probing the transformation of a material during its application. This technique is proposed a practical tool for formulators in their efforts to design products with desired textural attributes. METHODS: A non-linear rheological technique termed LAOS was utilized to capture the textural expression perceived by consumers. Lissajous plots (stress vs. strain or strain rate) provide a fingerprint of the formula and are utilized to both analyse the thickening mechanism and monitor the influence of various parameters, such as the chemistry, molecular properties, colloidal parameters and processing conditions. RESULTS: In this study, we showcased several approaches for modifying the texture of personal care formulations and show the influence of various parameters on the characteristics of the Lissajous curves and their relation to sensorial perception. This fingerprinting technique shows that increasing the molecular weight or hydrophobic modification boosts the elasticity and thickening efficiency of a given polymer. Differences in the chemistry of rheological ingredients also influence the characteristic Lissajous fingerprint. In high concentration surfactant systems, which tend to form worm-like micelles, their unique Lissajous fingerprints indicate structure rebuild because of fast kinetics at large but slow deformations. Analysis of lamellar gel-based hair conditioner formulations demonstrates the unique high yield stress of these types of materials, accompanied by the fast breakdown transition from a solid to viscous structure because of their crystalline lamellar gel structure. CONCLUSION: The LAOS technique presented in this article is intended to better capture the textural expression perceived by consumers. Lissajous plots-generated from the LAOS experimental data-provide a fingerprint of the tested formula and are utilized to both analyse the thickening mechanism and monitor the influence of various parameters, such as the chemistry and molecular weight of the thickener, pH of the formula medium and influence of other ingredients in the formula (surfactants, emulsifiers, etc.).

OBJECTIF: Les techniques rhéologiques conventionnelles dans la région viscoélastique linéaire fournissent des informations sur la configuration spatiale des composants microstructurels des formulations de produits cosmétiques dans leur état « au repos ¼. Mais elles ne décrivent pas l'expérience de texture associée à des déformations importantes et rapides lors de l'application quotidienne par les consommateurs. Dans cette étude, nous présentons une technique rhéologique non conventionnelle, le cisaillement oscillatoire à grande amplitude (Large Amplitude Oscillatory Shear, LAOS), pour examiner la transformation d'un matériau pendant son application. Cette technique est proposée comme outil pratique pour aider les formulateurs dans leurs efforts pour concevoir des produits qui ont les attributs texturaux désirés. MÉTHODES: Une technique rhéologique non linéaire appelée LAOS a été utilisée pour capturer le style textural perçu par les consommateurs. Les courbes de Lissajous (stress vs contrainte ou taux de déformation) fournissent une empreinte de la formule et sont utilisées pour analyser le comportement épaississant et surveiller l'influence de divers paramètres, tels que les propriétés moléculaires et chimiques, les paramètres colloïdaux et les conditions de traitement. RÉSULTATS: Dans cette étude, nous avons présenté plusieurs approches pour modifier la texture des formulations cosmétiques et montrer l'influence de divers paramètres sur les caractéristiques des courbes de Lissajous et leur relation avec la perception sensorielle. Cette technique d'empreintes montre que l'augmentation du poids moléculaire ou la modification hydrophobe stimule l'élasticité et l'épaississement d'un polymère donné. Les différences dans la chimie des ingrédients rhéologiques influencent également l'empreinte caractéristique de Lissajous. Dans les systèmes de tensioactifs à haute concentration, qui ont tendance à former des micelles semblables à des vers, leurs empreintes Lissajous uniques indiquent une reconstruction de la structure à cause de cinétiques rapides dans leur ensemble mais des déformations lentes. L'analyse des des formulations lamellaires d'après-shampooing à base de gel démontre le stress unique à haut rendement de ces types de matériaux, accompagnés par la transition de répartition rapide d'une structure solide à visqueuse à cause de leur structure lamellaire cristalline. CONCLUSION: La technique LAOS présentée dans cet article vise à mieux appréhender le style de texture perçu par les consommateurs. Les graphiques de Lissajous, générées à partir de données LAOS expérimentales, fournissent une empreinte de la formule testée et sont utilisés pour analyser le mécanisme épaississant et surveiller l'influence de divers paramètres, tels que la chimie et le poids moléculaire de l'épaississant, le Ph moyen et l'influence des autres ingrédients (tensioactifs, émulsifiants, etc.) dans la formule.

Allostery and Epistasis: Emergent Properties of Anisotropic Networks.

Understanding the underlying mechanisms behind protein allostery and non-additivity of substitution outcomes (i.e., epistasis) is critical when attempting to predict the functional impact of mutations, particularly at non-conserved sites. In an effort to model these two biological properties, we extend the framework of our metric to calculate dynamic coupling between residues, the Dynamic Coupling Index (DCI) to two new metrics: (i) EpiScore, which quantifies the difference between the residue fluctuation response of a functional site when two other positions are perturbed with random Brownian kicks simultaneously versus individually to capture the degree of cooperativity of these two other positions in modulating the dynamics of the functional site and (ii) DCIasym, which measures the degree of asymmetry between the residue fluctuation response of two sites when one or the other is perturbed with a random force. Applied to four independent systems, we successfully show that EpiScore and DCIasym can capture important biophysical properties in dual mutant substitution outcomes. We propose that allosteric regulation and the mechanisms underlying non-additive amino acid substitution outcomes (i.e., epistasis) can be understood as emergent properties of an anisotropic network of interactions where the inclusion of the full network of interactions is critical for accurate modeling. Consequently, mutations which drive towards a new function may require a fine balance between functional site asymmetry and strength of dynamic coupling with the functional sites. These two tools will provide mechanistic insight into both understanding and predicting the outcome of dual mutations.

Determinants of quality of life among pregnant women in the city centre of the Central Anatolia region of Turkey.

BACKGROUND: To evaluate the quality of life in pregnancy is very important because of the changes in the female body during pregnancy. Quality of life should be evaluated in terms of health protection during pregnancy, prevention of health problems and treatment. AIMS: The aim of this study is to determine the quality of life and the affecting factors by trimesters of pregnancy. METHODS: The population of this cross-sectional study consisted of pregnant women in a city center of the Central Anatolia region of Turkey. The study included 12 districts across a range of socioeconomic structures. Every district was selected by a simple random sampling method. The study was conducted by the researchers in the home of pregnant women by face to face interview method. The data were collected using "Personal Information Form" and "Quality of Life Scale". The total sample consisted of 1010 pregnant women, 192 of which were in first trimester, 277 of which were in second trimester and 541 of which were in third trimester. Data were analyzed using Statistical Package for Social Sciences (SPSS). RESULTS: There was no statistically significant difference between trimesters in physical domain (P = 0.96), mental domain (P = 0.94) and social domain (P = 0.47) of quality of life scale and there was a difference only in environmental domain (P = 0.02). The lowest quality of life in all three trimesters was found to be in physical domain. CONCLUSION: There was no statistically significant difference between trimesters in physical, mental and social domains of quality of life scale and there was a difference only in environmental domain. The lowest quality of life scores in all three trimesters were in the physical domain. The quality of life of pregnant women differed according to the trimesters and some sub-dimensions of quality of life of pregnant women were negatively affected in all three timester.

Coevolving residues inform protein dynamics profiles and disease susceptibility of nSNVs.

The conformational dynamics of proteins is rarely used in methodologies used to predict the impact of genetic mutations due to the paucity of three-dimensional protein structures as compared to the vast number of available sequences. Until now a three-dimensional (3D) structure has been required to predict the conformational dynamics of a protein. We introduce an approach that estimates the conformational dynamics of a protein, without relying on structural information. This de novo approach utilizes coevolving residues identified from a multiple sequence alignment (MSA) using Potts models. These coevolving residues are used as contacts in a Gaussian network model (GNM) to obtain protein dynamics. B-factors calculated using sequence-based GNM (Seq-GNM) are in agreement with crystallographic B-factors as well as theoretical B-factors from the original GNM that utilizes the 3D structure. Moreover, we demonstrate the ability of the calculated B-factors from the Seq-GNM approach to discriminate genomic variants according to their phenotypes for a wide range of proteins. These results suggest that protein dynamics can be approximated based on sequence information alone, making it possible to assess the phenotypes of nSNVs in cases where a 3D structure is unknown. We hope this work will promote the use of dynamics information in genetic disease prediction at scale by circumventing the need for 3D structures.

Muscle structure and gene expression in pectoralis major muscle in response to deep pectoral myopathy induction in fast- and slow-growing commercial broilers.

1. The objective of this study was to determine muscle structure and gene expression in pectoralis major (p. major) muscle of broilers in response to deep pectoral myopathy (DPM) induction. 2. A total of 160 chickens from slow- and fast-growing broilers were raised under same conditions. Half of the broilers from each strain were encouraged to wing flap when they reached 2800 g body weight. Pectoralis minor (p. minor) muscle of the broilers was inspected for the occurrence of DPM and p. major samples were collected from broilers with or without DPM. The muscle fibre area and number, capillary number and the signalling pathways of vascular development (vascular endothelial growth factor A, VEGFA) and muscle contraction regulation (actin alpha 1, ACTA1; myosin light chain kinase 2, MYLK2 and ATPase Ca+2 transporting gene 1, ATP2A1) were studied in p. major muscle. 3. DPM induction increased fibre area of p. major muscle with a greater rate in the slow-growing strain compared with fast-growing line. Although the capillary number was higher in slow-growing compared with fast-growing broilers, in the case of DPM induction, the number of capillaries was similar between strains. 4. Expression of VEGFA, MYLK2 and ATP2A1 was greater in slow- than in fast-growing broilers. DPM induction increased expression of ACTA1, VEGFA and ATP2A1 in p. major muscle of broilers from both strains; however, MYLK2 expression was downregulated. 5. Changes in capillary density and expression of VEGFA found in the p. major muscle of broilers with DPM suggest increased blood flow to increase oxygen availability. The upregulation of ATP2A1 by DPM induction could be attributable to alterations in calcium ion transportation from the cytoplasm into the sarcoplasmic reticulum. 6. The results are evidence of changes in muscle structure and gene expression pathways in p. major muscle of broilers with DPM.

The effect of maternal fatigue on breastfeeding.

BACKGROUND: Postpartum fatigue means tiredness, sense of suffocation, and decreased physical and mental capacity. Fatigue reduces postpartum women's ability of concentrate, which may increase the frequency of postpartum depression, and their babies and cause babies' weaning off breastmilk earlier. AIM: Postpartum fatigue reduces the ability of mothers to concentrate and has a negative effect on communication between mothers and their babies. This study was performed to determine the effect of fatigue on breastfeeding and breastfeeding behaviors in postpartum women. SUBJECTS AND METHODS: The study had a descriptive desing and was carreid out in a postpartum clinic of a maternal, obstetric, and pediatric diseases hospital. It included 374 women giving normal vaginal birth. Data were gathered with a socio-demographic features form and Visual Analogue Scale for Fatigue. RESULTS: The mean score was 6,91 ± 2,25 for the subscale fatigue and 2,38 ± 0,91 for the subscale energy. The women reporting that it was not difficult to give birth and that they had little or some fatigue had significantly higher scores for energy (P = 0.001). The women starting to breastfeed in the hour of giving birth (P = 0.003) and the women breastfeeding at 1-hour intervals (P = 0.100) had a lower score for fatigue. The women not needing help while breastfeeding had a significantly lower score for fatigue (P = 0.001), while those reporting to give additional food had a significantly higher score for fatigue (P = 0.014). CONCLUSION: Women feel tired in the early postpartum period due to giving birth and their tiredness is increased by breastfeeding and infant care.

Mutations Utilize Dynamic Allostery to Confer Resistance in TEM-1 ß-lactamase.

ß-lactamases are enzymes produced by bacteria to hydrolyze ß-lactam antibiotics as a common mechanism of resistance. Evolution in such enzymes has been rendering a wide variety of antibiotics impotent, therefore posing a major threat. Clinical and in vitro studies of evolution in TEM-1 ß-lactamase have revealed a large number of single point mutations that are responsible for driving resistance to antibiotics and/or inhibitors. The distal locations of these mutations from the active sites suggest that these allosterically modulate the antibiotic resistance. We investigated the effects of resistance driver mutations on the conformational dynamics of the enzyme to provide insights about the mechanism of their long-distance interactions. Through all-atom molecular dynamics (MD) simulations, we obtained the dynamic flexibility profiles of the variants and compared those with that of the wild type TEM-1. While the mutational sites in the variants did not have any direct van der Waals interactions with the active site position S70 and E166, we observed a change in the flexibility of these sites, which play a very critical role in hydrolysis. Such long distance dynamic interactions were further confirmed by dynamic coupling index (DCI) analysis as the sites involved in resistance driving mutations exhibited high dynamic coupling with the active sites. A more exhaustive dynamic analysis, using a selection pressure for ampicillin and cefotaxime resistance on all possible types of substitutions in the amino acid sequence of TEM-1, further demonstrated the observed mechanism. Mutational positions that play a crucial role for the emergence of resistance to new antibiotics exhibited high dynamic coupling with the active site irrespective of their locations. These dynamically coupled positions were neither particularly rigid nor particularly flexible, making them more evolvable positions. Nature utilizes these sites to modulate the dynamics of the catalytic sites instead of mutating the highly rigid positions around the catalytic site.

The occurrence of deep pectoral myopathy in broilers and associated changes in breast meat quality.

1. Two experiments were conducted to determine the effect of slaughter weight on the incidence and intensity of deep pectoral myopathy (DPM) of M. pectoralis minor (p. minor muscle) in commercial conditions in Turkey and to evaluate the impact of DPM on meat quality traits of pectoralis major (p. major) muscle in broilers. 2. In Experiment 1, a total of 116 250 carcasses from 59 Ross-308 broiler flocks, classified according to slaughter weight as 2.0-2.2, 2.2-2.4, 2.4-2.6 and >2.6 kg, were evaluated for occurrence of DPM. In Experiment 2, p. major samples from unaffected broilers and each DPM stage were evaluated for meat quality, oxidant and antioxidant properties, nutritional value and fatty acid profile. DPM was characterised as 1: muscles with coagulative necrosis, 2: muscles with fibrous tissue texture and pink to plumb and 3: muscles with green necrotic area. 3. The average incidence of DPM was found to be 0.73% in Experiment 1 and independent of slaughter weight. 4. In Experiment 2, p. major muscle of broilers with DPM 1 and 2 had higher pH values with higher redness and drip loss. All DPM stages resulted in an increase in lipid content and malondialdehyde activity and lowered ash content of p. major muscle compared with unaffected birds. DPM 2 increased superoxide dismutase and glutathione peroxidase activities in M. p. major. The p. major of broilers with DPM had lower content of C18:2 conjugated linoleic and C20:3n-6 fatty acids than those of unaffected broilers. Lower Δ6 desaturase and thiosterase activities and 18:2n-6 to 18:3n-3 ratio were observed for all DPM stages compared to unaffected. 5. It was concluded that these changes obtained in p. major muscle of broilers with DPM might indicate biochemical characteristics of muscle degenerations.

Plasma copeptin levels in the patients with gastrointestinal bleeding.

INTRODUCTION: Gastrointestinal bleeding is a significant cause of morbidity and mortality worldwide. In addition, it constitutes an important part of health expenditures. In this study, we aimed to determine whether there is a relationship between plasma copeptin levels and the etiology, location and severity of gastrointestinal bleeding. MATERIALS AND METHODS: This study was performed prospectively in 104 consecutive patients who were admitted to an emergency department with complaints of bloody vomiting or bloody or black stool. To evaluate the level of biochemical parameters such as Full Blood Count (FBC), serum biochemistry, bleeding parameters and copeptin, blood samples were obtained at admission. For the copeptin levels, 2 more blood samples were obtained at the 12th and 24th hours after admission. The values obtained were compared using statistical methods. RESULTS: In terms of the etiology of bleeding, the copeptin levels in the patients with peptic ulcer were higher than the levels in patients with other gastrointestinal bleeding. However, the difference was not statistically significant. There were no significant differences among all groups' 0th, 12th and 24th hour levels of copeptin. DISCUSSION: We conclude that copeptin cannot be effectively used as a biochemical parameter in an emergency department to determine the etiology and location of gastrointestinal bleeding. It can, however, be used to make decisions on endoscopy and the hospitalization of patients with suspected gastrointestinal bleeding.

Effects of enhancing vitamin D status by 25-hydroxycholecalciferol supplementation, alone or in combination with calcium and phosphorus, on sternum mineralisation and breast meat quality in broilers.

1. The aim of the present study was to examine the effects of improving vitamin D status in broiler diets by supplementary 25-hydroxycholecalciferol (25OHD3), alone or in combination with calcium (Ca) and available phosphorus (aP), on live performance, sternum mineralisation and breast meat quality in broilers. 2. A total of 936 1-d-old Ross 308 broilers were used in the study. After gender determination at the hatchery, chicks from each sex were randomly distributed into three dietary treatments. The following dietary treatments were used in the experiment from hatch to 38 d: (1) A control diet formulated to meet all of the nutrient requirements of broiler chicks according to the management guide; (2) The control diet supplemented with 18.7-15.0 µg/kg of 25OHD3; and (3) The control diet supplemented with 18.7-15.0 µg/kg of 25OHD3 plus Ca + aP. 3. Improvement in vitamin D status by 25OHD3 supplementation, alone or in combination with Ca and aP, had no effect on body weight and feed conversion ratio of broilers. 4. The serum 25OHD3 concentration significantly increased with 25OHD3 and 25OHD3 plus Ca + aP supplementation (P < 0.05), whereas the ionised Ca and Mg concentrations remained unchanged. 5. Sternum absolute weight, ash content and the concentrations of Ca and P significantly increased (P < 0.01) with supplementation of 25OHD3, alone or in combination with Ca + aP. 6. Supplemental 25OHD3, alone or in combination with Ca + aP, slightly increased pH24 (P = 0.05) and decreased (P < 0.01) squeezable water loss in breast meat, whereas it had no significant effect on lightness, yellowness and sarcoplasmic protein solubility. 7. In conclusion, the results suggested that enhancing vitamin D status by 25OHD3 supplementation alone or in combination with Ca + aP may improve sternum structure and mineral accretion. Furthermore, supplemental 25OHD3, even in a nutritionally complete diet, may offer an effective way to improve protein solubility in female broilers.

Effects of 2100 MHz radio frequency radiation on ductus epididymis tissue in rats.

PURPOSE: The use of mobile phones is widespread since the beginning of 1990s. A great debate exists about the possible damage that the Radio Frequency - RF radiation from mobile phones exerts on different organs. The objective of this study was to investigate the possible histopathological effects of 2100 MHz RF radiation on rat ductus epididymis tissue using a light microscopy and immunohistochemical method after one or two month exposure. MATERIALS AND METHODS: The study was performed on 36 adult Wistar albino rats. 2100 MHz RF radiation was used with a specific absorption rate (SAR) of 0.36 W/kg for 30 min/day, 6 days per week for one or two months. There were 3 groups (n = 6 for each group): one month RF exposed group, two months RF exposed group, and the control group. RESULTS: At the end of the study, the structural changes in ductus epididymis tissue were evaluated. In both 2100 MHz RF exposed groups, the rat ductus epididymis sperm were not observed in some channels, a reduction in sperm density in some of the channels drew an attention. The loss of connective tissue and edematous areas were observed in cross channel interstitial connective tissue. In addition, it was observed that vascularization was highly increased with respect to the control group in cross-channel interstitial connective tissue. CONCLUSION: 2100 MHz RF exposure resulted in some structural changes in the male genital ducts of rats (Tab. 1, Fig. 5, Ref 20).