Influence of the incorporation of cholesterol on the doubling time and on the arrhenius and hill plots of two membrane-bound enzymes ofEscherichia coli K12

Escherichia coli was grown at 37°C with increasing cholesterol concentrations in the growth medium. Under these conditions, it was shown that neither the phospholipid species nor the fatty acid composition were affected by the incorporation of cholesterol. On the other hand, the doubling time (t_d) was increased; two membrane-bound enzymes, (Ca⁺⁺)-ATPase and D-lactate-dehydrogenase, were modified in the temperature-dependence activities, and the (Ca^±±)-ATPase changed its Hill coefficient for the inhibition by Na⁺. This last parameter was the most sensitive in detecting very low cholesterol incorporations to the cytoplasmic membranes.     

Allosteric transitions and membrane-bound ATPase from rat tissues: The effect of fat deprivation on the allosteric inhibition by fluoride

In rats red a fat-sufficient diet, ATPases (ATP phosphohydrolase, EC 3.6.1.3) from heart, kidney and brain microsomes showed allosteric kinetics for the inhibition by F^?, with values ofn = ?2.0. In rats fed a far-free diet, the values ofn for the ATPases changed from ?2.0 to ?1.0 in heart and kidney microsomes. When these animals were then fed a fat-sufficient diet the values ofn reached the control values. In brain microsomal ATPases no modification of the values ofn were found between both groups of animals. The regulatory properties of the membrane on bound ATPases are discussed.     

CALU-3 lung cells three-dimensionally assembled onto CellFate® matrix present angiotensin-converting enzyme-2 activity

Currently, there is a great need for the development of three-dimensional (3D) in vitro lung models. Particularly, the production of a suitable 3D model of pulmonary epithelium for understanding the pathophysiology of diseases such as the COVID-19 must consider the tissue architecture and presence, for example, of the angiotensin-converting enzyme-2 (ACE-2) in the cells. Different polymeric membranes are being used to support cell culturing, especially of lung cells, however, there is still no information about the culture of these cells onto bacterial nanocellulose (BNC) matrices. We have used the BNC matrix CellFate® as a support for the assembly of a 3D in vitro model of lung epithelium, composed of human lung fibroblasts (HLF) and lung adenocarcinoma cells (CALU-3). CellFate® matrices were made from bacterial fermentation resulting in a natural and biocompatible biopolymer. Cells were cultured onto CellFate® and maintained in a 5% CO₂ humidified atmosphere at 37°C. Cell viability was assessed by the resazurin method The samples were, then, exposed to the air–liquid interface (ALI), and histologically analyzed. ACE-2 activity was verified on the hydrolyze of the fluorogenic substrate Mca-APK(Dnp)-OH, and its presence was evaluated by flow cytometry. The expression of the anionic transporter SLCO3A1 was evaluated by qPCR. Cell viability analysis indicates that CellFate® was not toxic to these cells. By flow cytometry, the presence of the ACE-2 was identified in the CALU-3 cells surface corroborating the results obtained from enzymatic activity analysis. The SLCO3A1 transporter expression was identified in cells cultured onto CellFate®, but not in cells cultured onto the transwell (control). CALU-3 cells cultivated onto CellFate® resulted in a pseudostratified organization, a typical morphology of the human respiratory tract epithelium. The current model opens perspectives for studies involving physiological characterization, improving its relevance for the understanding of the pathophysiology of diseases as well as the response to drugs.     

Relative growth and onset of morphological sexual maturity of the freshwater crab Sylviocarcinus pictus in a river of the Caatinga of northeastern Brazil

The aim of this study was to investigate the relative growth and onset of morphological sexual maturity of the freshwater crab Sylviocarcinus pictus. Specimens were collected every month from October 2013 to September 2014, at night, on a stretch of the river Guaribas, Piauí, Brazil. Crabs were sexed and their carapace width (CW, independent variable), carapace length (CL), cheliped propodus length (PL) and height (PH), gonopod length (GL), and abdomen width (AW) (dependent variables) were measured. These measurements were related to characterise relative growth and possible sex differences. On average males were larger than females (p = 0.0001). Size at the onset of morphological sexual maturity was defined by relating CL vs. PL for males (30.82 mm) and CL vs. AW for females (28.63 mm). These are considered secondary sexual characters and reflect initial size at morphological sexual maturity with greater precision. The differential cheliped growth of males may be related to courting and disputes with other males, while the allometric growth of the abdomen of females indicates increased probability of reproductive success.     

Adverse pregnancy outcomes are associated with Plasmodium vivax malaria in a prospective cohort of women from the Brazilian Amazon

BackgroundMalaria in Brazil represents one of the highest percentages of Latin America cases, where approximately 84% of infections are attributed to Plasmodium (P.) vivax. Despite the high incidence, many aspects of gestational malaria resulting from P. vivax infections remain poorly studied. As such, we aimed to evaluate the consequences of P. vivax infections during gestation on the health of mothers and their neonates in an endemic area of the Amazon.Methods and findingsWe have conducted an observational cohort study in Brazilian Amazon between January 2013 and April 2015. 600 pregnant women were enrolled and followed until delivery. After applying exclusion criteria, 329 mother-child pairs were included in the analysis. Clinical data regarding maternal infection, newborn’s anthropometric measures, placental histopathological characteristics, and angiogenic and inflammatory factors were evaluated. The presence of plasma IgG against the P. vivax (Pv) MSP1₁₉ protein was used as marker of exposure and possible associations with pregnancy outcomes were analyzed. Multivariate logistic regression analysis revealed that P. vivax infections during the first trimester of pregnancy are associated with adverse gestational outcomes such as premature birth (adjusted odds ratio [aOR] 8.12, 95% confidence interval [95%CI] 2.69–24.54, p < 0.0001) and reduced head circumference (aOR 3.58, 95%CI 1.29–9.97, p = 0.01). Histopathology analysis showed marked differences between placentas from P. vivax-infected and non-infected pregnant women, especially regarding placental monocytes infiltrate. Placental levels of vasomodulatory factors such as angiopoietin-2 (ANG-2) and complement proteins such as C5a were also altered at delivery. Plasma levels of anti-PvMSP1₁₉ IgG in infected pregnant women were shown to be a reliable exposure marker; yet, with no association with improved pregnancy outcomes.ConclusionsThis study indicates that P. vivax malaria during the first trimester of pregnancy represents a higher likelihood of subsequent poor pregnancy outcomes associated with marked placental histologic modification and angiogenic/inflammatory imbalance. Additionally, our findings support the idea that antibodies against PvMSP1₁₉ are not protective against poor pregnancy outcomes induced by P. vivax infections.     

Emotional distress and its socio-political correlates in Salvadoran refugees: Analysis of a clinical sample

The emotional distress responses of refugees cannot be adequately understood using the traditional notions of stress and adaptation. In these populations it is necessary to consider the relations between emotional distress and socio-political context, particularly the processes of terror and intimidation and the conditions of migratory illegality and social marginality.This study analyses the patterns of emotional distress in a clinical sample of 71 Salvadoran refugees in an urban center of the United States. Case histories are presented and patterns of trauma, distress and associated life problems analyzed. It is argued that distress patterns reflect the particular socio-political conditions of women and men and represent the embodiment of the conflicts that refugees face. The concept of illness is used to link distress patterns and socio-political context and to avoid the reductionism of psychiatric categories.     

The convenience of the use of allosteric "probes" for the study of lipid--protein interactions in biological membranes: thermodynamic considerations.

One of the most commonly used methods to study enzyme (protein)-structure interactions at a more specific level is the use of the Arrhenius plots to detect the influence of the “environment” on the enzyme. We want to point out here that the use of a suitable “allosteric enzyme” would be a more sensitive method to detect influences of the environment than the study of Arrhenius plots. According to simple thermodynamic considerations, a change of more than 2.8 kcal/mol in the interaction between enzyme and membrane would be needed to give a noticeable change in the position of the break (T_i) of the corresponding Arrhenius plot. On the other hand, feeble changes in the membrane-enzyme interaction, of the order of 0·7–0·8 kcal/mol, would be enough to give a significant change in the values of n (Hill coefficient).