Aromatic circular dichroism in globular proteins: applications to protein structure and folding

1994 Fall.Includes bibliographical references (pages 334-342).Covers not scanned.Print version deaccessioned 2020.The exciton couplet approach was applied to estimate the circular dichroism (CD) of Trp side-chains in proteins. Calculations were performed by the origin-independent version of the matrix method, either for the indole Bb transition only or for the six lowest energy indole transitions. The dependence of the CD of a Trp pair upon its distance and geometry has been analyzed. It was predicted that mixing with far-uv transitions are as important in determining the CD intensity of the near-uv transitions as the coupling among near-uv transition. The effects of varying exposure of Trp chromophores and nearby charges on Trp CD have been examined. A survey of a large number of proteins from the Protein Data Bank reveals a number of cases where readily detectable exciton couplets are predicted to result from the exciton coupling of Trp Bb bands. The predicted CD spectra are generally couplets, often dominated by the contributions of the closest pair, but sometimes exhibit three distinct maxima. This CD depends on the distance and relative orientation of Trp pairs and thus reflects the spatial arrangement of Trp residues in the protein. It was shown that Trp side chains can make significant contributions to the CD of proteins in the far ultraviolet. The distance dependence of exciton splitting, rotational and couplet strengths of Trp pairs show general agreement with theoretical predictions. In several cases, changes in protein Trp CD can be attributed to a specific Trp pair and explained as a definite change in its conformation. Applications of the exciton couplet approach are discussed for various crystal forms of hen lysozyme, turkey and human lysozyme. Trp62 in hen and turkey lysozymes was found to be sensitive to the perturbations of the protein surface due to binding of substrate, antibodies and intermolecular contacts in the crystal. Conformational changes of Trp62 are predicted to have a strong effect on the overall Trp CD of lysozyme. Predicted Trp CD is compared with experimental results for various lysozymes, a-chymotrypsin and chymotrypsinogen A, concanavalin, dihydrofolate reductase and ribonuclease from Bacillus intermedius 7P (binase). The calculated near-uv CD for hen lysozyme matches the experimental amplitude. Correlation of conformational changes in proteins with Trp CD is shown for a-chymotrypsin and chymotrypsinogen A. We found that the exciton couplet approach might be useful in relating Trp CD and changes in protein structure upon local mutations and conformational changes involved in enzyme activation. Small globular proteins are usually composed of a single structural domain and undergo cooperative denaturation. We have demonstrated that a protein with a single structural domain, binase, and a protein with multiple structural domains, porcine pepsin, contain fewer cooperative regions (energetic domains) under the conditions optimal for their functional activity. The study was performed by combining a CD analysis of the structural changes in the proteins during thermal denaturation and under various solvent conditions with thermodynamic properties observed by scanning microcalorimetry. Estimates of secondary structure were obtained from CD spectra, taking side-chain CD into account. It was found that neither of the proteins show any changes in secondary structure or local environment of aromatic amino acids upon separation of the energetic domains. The structural regions in binase corresponding to energetic domains were identified. It was shown that binase is converted from a single cooperative system into two separate energetic domains when ion pairs are disrupted, whereas the size of cooperative units in pepsin decrease as the electrostatic repulsion between regions in the molecule increases

Informational Behavior in the COVID-19 Pandemic: Psychological Predictors

The core problem of the COVID-19 pandemic for psychologists is to find out how people cope with the stress of isolation and the threat of fatal disease. The scale of the pandemical impact on the psychological well-being of an individual has still no knowledge and psychological predictors which the impact depends on need to be identified. This paper presents an empirical study of informational behavior and its psychological predictors in the pandemic. The research was held online in April-May 2020. The total amount of 165 participants, aged from 18 to 66. The subjects were chosen from a randomly selected sample. The participants were asked to estimate their informational consumption in pandemic. Tolerance to ambiguity, hardiness and anxiety was studied in groups distinguished according to changes in informational consumption. The findings of this study indicate a significant correlation between informational behavior and psychological characteristics related to coping with stress. Besides the analysis proved a negative correlation between reactive and personal anxiety and tolerance to ambiguity, hardiness and its components. We have confirmed that increased informational comsumption can be considered as a coping strategy for overcoming the pandemic social isolation among respondents with low hardiness and tolerance to ambiguity. Stable and decreased informational consumption indicates that respondents with high hardiness and tolerance to ambiguity and low state and trait anxiety don’t need to consume information for coping with difficulties of pandemic self-isolation. Future work will concentrate on expanding the list of psychological predictors of informational behavior and studying the features of their interaction in different situations

Variability of fertility indicators in Ayrshire firstcalf heifers under the influence of early lactation

The basic value for optimizing the reproduction of the herd in dairy cattle breeding is the ability of cows to procreate offspring - fertility. It is a complex feature, characterized by many indicators and due to a complex of factors. The goal of our work was to reveal and to study these indicators and factors. The studies were carried out on Ayrshire cows of the Megrega breeding farm (the Republic of Karelia). The average milk yield per cow is over 9,000 kg of milk per year. Fertility indicators were taken into account for 5 years according to the data of 3866 lactations. The following fertility indicators were analysed: the indifference period; the period of insemination; the service period; fertilization from the first insemination; conception index (number of inseminations per conception); early embryonic death. We have analysed the relationship of these indicators with age, the amount of milk yield in general for lactation and during the early lactation period. An increase in the level of milk yield of cows during the current lactation up to 10,000 kg of milk or more was accompanied by a decrease in fertilization after the first insemination from 78.1 to 33.6%, as well as a significant deterioration in other main indicators of reproduction. The study established the relationship between the level of productivity of first-calf heifers during the early lactation period and fertility indicators. The greatest influence on fertility indicators during the early lactation period and insemination was exerted by the level of milk yield in the 1st month of the first lactation. The worst reproductive abilities were shown by first-calf heifers with an average daily milk yield of 34 kg or more. The results obtained can be used in further research on the development of selection indices, selection according to which can provide a high genetic trend in milk yield while maintaining and developing the progressive fertility of dairy cows

Divergent Annexin A1 expression in periphery and gut is associated with systemic immune activation and impaired gut immune response during SIV infection.

HIV-1 disease progression is paradoxically characterized by systemic chronic immune activation and gut mucosal immune dysfunction, which is not fully defined. Annexin A1 (ANXA1), an inflammation modulator, is a potential link between systemic inflammation and gut immune dysfunction during the simian immunodeficiency virus (SIV) infection. Gene expression of ANXA1 and cytokines were assessed in therapy-naïve rhesus macaques during early and chronic stages of SIV infection and compared with SIV-negative controls. ANXA1 expression was suppressed in the gut but systemically increased during early infection. Conversely, ANXA1 expression increased in both compartments during chronic infection. ANXA1 expression in peripheral blood was positively correlated with HLA-DR+CD4+ and CD8+ T-cell frequencies, and negatively associated with the expression of pro-inflammatory cytokines and CCR5. In contrast, the gut mucosa presented an anergic cytokine profile in relation to ANXA1 expression. In vitro stimulations with ANXA1 peptide resulted in decreased inflammatory response in PBMC but increased activation of gut lymphocytes. Our findings suggest that ANXA1 signaling is dysfunctional in SIV infection, and may contribute to chronic inflammation in periphery and with immune dysfunction in the gut mucosa. Thus, ANXA1 signaling may be a novel therapeutic target for the resolution of immune dysfunction in HIV infection

PPARα-targeted mitochondrial bioenergetics mediate repair of intestinal barriers at the host-microbe intersection during SIV infection.

Chronic gut inflammatory diseases are associated with disruption of intestinal epithelial barriers and impaired mucosal immunity. HIV-1 (HIV) causes depletion of mucosal CD4+ T cells early in infection and disruption of gut epithelium, resulting in chronic inflammation and immunodeficiency. Although antiretroviral therapy (ART) is effective in suppressing viral replication, it is incapable of restoring the "leaky gut," which poses an impediment for HIV cure efforts. Strategies are needed for rapid repair of the epithelium to protect intestinal microenvironments and immunity in inflamed gut. Using an in vivo nonhuman primate intestinal loop model of HIV/AIDS, we identified the pathogenic mechanism underlying sustained disruption of gut epithelium and explored rapid repair of gut epithelium at the intersection of microbial metabolism. Molecular, immunological, and metabolomic analyses revealed marked loss of peroxisomal proliferator-activated receptor-α (PPARα) signaling, predominant impairment of mitochondrial function, and epithelial disruption both in vivo and in vitro. To elucidate pathways regulating intestinal epithelial integrity, we introduced probiotic Lactobacillus plantarum into Simian immunodeficiency virus (SIV)-inflamed intestinal lumen. Rapid recovery of the epithelium occurred within 5 h of L. plantarum administration, independent of mucosal CD4+ T cell recovery, and in the absence of ART. This intestinal barrier repair was driven by L. plantarum-induced PPARα activation and restoration of mitochondrial structure and fatty acid β-oxidation. Our data highlight the critical role of PPARα at the intersection between microbial metabolism and epithelial repair in virally inflamed gut and as a potential mitochondrial target for restoring gut barriers in other infectious or gut inflammatory diseases

In vivo gene expression profiling of human intestinal epithelial cells: analysis by laser microdissection of formalin fixed tissues

<p>Abstract</p> <p>Background</p> <p>The small intestinal epithelium mediates vital functions of nutrient absorption and host defense. The spatial organization of the epithelial cells along the crypt-villus axis segregates them into regions of specialized function. However, the differences in transcriptional programming and the molecular machinery that governs the migration, adhesion, and differentiation of intestinal epithelial cell lineages in humans remain under-explored. To increase our understanding of these mechanisms, we have evaluated gene expression patterns of ileal epithelial cells isolated by laser capture microdissection from either the villus epithelial or crypt cell regions of healthy human small intestinal mucosa. Expression profiles in villus and crypt epithelium were determined by DNA microarray, quantitative real-time PCR, and immunohistochemistry based methods. The expression levels of selected epithelial biomarkers were also compared between gastrointestinal tissues.</p> <p>Results</p> <p>Previously established biomarkers as well as a novel and distinct set of genes believed to be linked to epithelial cell motility, adhesion, and differentiation were found to be enriched in each of the two corresponding cell populations (GEO accession: GSE10629). Additionally, high baseline expression levels of innate antimicrobials, alpha defensin 5 (HD5) and regenerating islet-derived 3 alpha (Reg3A), were detected exclusively within the small bowel crypt, most notably in the ileum in comparison to other sites along the gastrointestinal tract.</p> <p>Conclusion</p> <p>The elucidation of differential gene expression patterns between crypt and villus epithelial cell lineages in human ileal tissue provides novel insights into the molecular machinery that mediates their functions and spatial organization. Moreover, our findings establish an important framework of knowledge for future investigations of human gastrointestinal diseases.</p

Predictors of visceral obesity in normal weight obstructive sleep apnea patients

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is epidemiologically related to adverse cardiovascular outcomes. The pathophysiology clues are metabolic changes and obesity. The most studied anthropometric predictors of obesity, such as body mass index (BMI), waist circumference (WC), are influenced by various factors such as sex, type of constitution, hydration balance. The normal range of BMI and WC limits the diagnostic search for metabolic disturbances and visceral obesity in patients with respiratory sleep distress and can lead to increased cardiovascular risks. AIMS: to investigate the visceral obesity predictors in normal weight patients with obstructive sleep apnea syndrome. MATERIALS AND METHODS: We had performed а cross-sectional study, 68 patients were examined with mean age of 38.24 &plusmn; 7.4 years. The main group (38 individuals) was represented by patients with OSAS. The control group consisted of healthy individuals without OSAS. Alternative markers of visceral obesity, such as lipid accumulation products, visceral obesity index, conicity index have been studied. RESULTS: In the main group we found different disorders of lipid metabolism such as the increase in triglyceride levels by 94%, low-density lipids by 32%, total cholesterol by 10% compared with the control group. Anthropometric evidence was obtained for excessive fat accumulation in patients with normal body weight and OSAS: WC was 89.6 &plusmn; 5.7 cm in the main group and was higher than in the control group 83.7 &plusmn; 6.3 cm (p = 0.024) due to an increase in the visceral fat compartment, as evidenced by the conicity index (67.2 &plusmn; 7.0 and 59.3 &plusmn; 6.2 respectively, p = 0.032) and waist to height ratio (0.58 &plusmn; 0.05 and 0.53 &plusmn; 0.04 in the main and control groups, respectively, p = 0.041). Correlation relationships between the severity of sleep apnea syndrome and visceral obesity indicators were revealed. CONCLUSIONS: Normal weight patients with breathing disorders are at risk of visceral fat obesity and, thereby, increased cardiovascular risk. Assessment of additional markers of visceral obesity in patients with normal body weight and sleep apnea is recommended to include in the dynamic observation programms

Sleep disorders interactions with obesity and type 2 diabetes

Obesity and type II diabetes are 21st century pandemia. These metаbolic disorders are in the focus of attention of various specialties: cardiologists, endocrinologists, nutritionists, therapists, and others. The high incidence of obesity and type II diabetes cardiovascular complications, such as myocardial infarction, stroke, chronic heart failure, dementia, determine the call of risk factors search. Modifiable factors may include sleep disturbances. Recent studies have revealed a connection between changes in sleep duration and metabolic disorders. However, to date, the mechanisms underlying this association have not been established. The aim of the review is to summarize existing epidemiological and experimental observations, as well as an analysis of possible pathophysiological mechanisms linking sleep duration with obesity and type II diabetes. The article considers current data suggesting a bi-directional association of sleep disorders with obesity and diabetes. Sleep disturbances are significant determinant of developing metabolic disorders. Sleep duration correction as one of therapeutic targets for cardiovascular complications of obesity and type II diabetes prevention

Bmp7 Functions via a Polarity Mechanism to Promote Cloacal Septation

During normal development in human and other placental mammals, the embryonic cloacal cavity separates along the axial longitudinal plane to give rise to the urethral system, ventrally, and the rectum, dorsally. Defects in cloacal development are very common and present clinically as a rectourethral fistula in about 1 in 5,000 live human births. Yet, the cellular mechanisms of cloacal septation remain poorly understood.We previously detected Bone morphogenetic protein 7 (Bmp7) expression in the urorectal mesenchyme (URM), and have shown that loss of Bmp7 function results in the arrest of cloacal septation. Here, we present evidence that cloacal partitioning is driven by Bmp7 signaling in the cloacal endoderm. We performed TUNEL and immunofluorescent analysis on cloacal sections from Bmp7 null and control littermate embryos. We found that loss of Bmp7 results in a dramatic decrease in the endoderm survival and a delay in differentiation. We used immunological methods to show that Bmp7 functions by activating the c-Jun N-terminal kinase (JNK) pathway. We carried out confocal and 3D imaging analysis of mitotic chromosome bundles to show that during normal septation cells in the cloacal endoderm divide predominantly in the apical-basal direction. Loss of Bmp7/JNK signaling results in randomization of mitotic angles in the cloacal endoderm. We also conducted immunohistochemical analysis of human fetal sections to show that BMP/phospho-SMAD and JNK pathways function in the human cloacal region similar as in the mouse.Our results strongly indicate that Bmp7/JNK signaling regulates remodeling of the cloacal endoderm resulting in a topological separation of the urinary and digestive systems. Our study points to the importance of Bmp and JNK signaling in cloacal development and rectourethral malformations