Physiological Agents Research Articles

GDF-11 prevents cardiomyocyte hypertrophy by maintaining the sarcoplasmic reticulum-mitochondria communication

Growth differentiation factor 11 (GDF11) is a novel factor with controversial effects on cardiac hypertrophy both in vivo and in vitro. Although recent evidence has corroborated that GDF11 prevents the development of cardiac hypertrophy, its molecular mechanism remains unclear. In our previous work, we showed that norepinephrine (NE), a physiological pro-hypertrophic agent, increases cytoplasmic Ca2+ levels accompanied by a loss of physical and functional communication between sarcoplasmic reticulum (SR) and mitochondria, with a subsequent reduction in the mitochondrial Ca2+ uptake and mitochondrial metabolism. In order to study the anti-hypertrophic mechanism of GDF11, our aim was to investigate whether GDF11 prevents the loss of SR-mitochondria communication triggered by NE. Our results show that: a) GDF11 prevents hypertrophy in cultured neonatal rat ventricular myocytes treated with NE. b) GDF11 attenuates the NE-induced loss of contact sites between both organelles. c) GDF11 increases oxidative mitochondrial metabolism by stimulating mitochondrial Ca2+ uptake. In conclusion, the GDF11-dependent maintenance of physical and functional communication between SR and mitochondria is critical to allow Ca2+ transfer between both organelles and energy metabolism in the cardiomyocyte and to avoid the activation of Ca2+-dependent pro-hypertrophic signaling pathways.

A Computational Framework for Preferential Switching of Competing Aβ Aggregation Pathways Based on Game Theory Approach

Polymorphism among amyloid-β (Aβ) aggregates are emerging as the main contributors to the observed phenotypic diversity in sporadic Alzheimer's disease (sAD). Aggregation of Aβ is susceptible to several heterotypic factors, and lipids (LDs) are the most important physiological agents to interact with, and modulate Aβ aggregation. Therefore, understanding the mechanism of how LDs modulate Aβ aggregation to generate polymorphic strains along competing pathways is crucial for understanding AD pathogenesis. Here, we demonstrate that steady-state switching dynamics between the competing aggregation pathways thar arise due to heterotypic Aβ-LD interactions can be modeled by a novel game theory approach. The game theory model abstracts the mass-action based non-linear, coupled dynamical system of competing pathways of aggregation and the corresponding Nash equilibrium points can predict the preferred pathways as a function of LD parameters and the level of dilution of the medium. While higher LD concentration leads to the generation of more micelle-bound oligomers (promoting the off-pathway of aggregation), higher levels of dilution of the medium result in dissociating micelle bound oligomers enabling higher conversion to fibrils (promoting the traditional on-pathway of aggregation). These models were subsequently validated by our previously developed ensemble kinetics simulations (EKS) that use ordinary differential equations based models of the competing pathways to estimate the rate constants of converting oligomers between on- and off-pathway aggregates; the combined computational framework accurately predicts the temporal rates and stability of oligomers formed under conditions predicted by controlled in vitro biophysical experiments. Hence, our results demonstrate the possibility of switching oligomeric strains between different competing pathways of Aβ aggregation besides providing a novel computational framework to model its dynamics.

Hemorrhoidal disease: Predilection sites, pattern of presentation, and treatment.

Background:An engorgement and prolapse of the anal cushion lead to haemorrhoidal disease. There are different anatomical sites and presentation of this common pathology which affects the quality of life.Aims:To study the predilection sites, presentation and treatment of haemorrhoidal disease.Patients and Method:A cohort study of patients diagnosed with haemorrhoids at an Endoscopy centre in Port Harcourt, Rivers State Nigeria from February 2014- July 2017.The patients were divided into 2 groups: A - asymptomatic and B- symptomatic. Variables studied included: demographics, anatomic variations, grade of haemorrhoids, clinical presentation and treatment. Statistical analysis was performed using IBM SPSS Statistics for Windows, version 20.0. Armonk, NY.Results:One hundred and twenty- one cases were included in study. There were 76 males and 45 males with age range from 15 -80 years (mean 51.9±13.1yrs). Bleeding per rectum was the most common presentation. The position frequency of haemorrhoids in decreasing order were: right posterior (34.1%); right anterior (28.2%); left lateral (17.1%); left posterior (7.6%). Multiple quadrants were affected in 58(72.5%) cases of external haemorrhoids. Grade I, II and III haemorrhoids were seen in 38 (31%), 31(26%) and 21(17%) cases respectively.Conclusion:The most common anatomical site of external haemorrhoids is the right posterior quadrant position; frequently, multiple sites are simultaneously affected. Goligher classification Grade 1 hemorrhoids are effectively treated by injection sclerotherapy using 50% dextrose solution; a cheap and physiologic sclerotherapy agent.

Targeting DNA Hypomethylation in Malignancy by Epigenetic Therapies.

DNA methylation is a chemically reversible epigenetic modification that regulates the chromatin structure and gene expression, and thereby takes part in various cellular processes like embryogenesis, genomic imprinting, X-chromosome inactivation, and genome stability. Alterations in the normal methylation levels of DNA may contribute to the development of pathological conditions like cancer. Even though both hypo- and hypermethylation-mediated abnormalities are prevalent in the cancer genome, the field of cancer epigenetics has been more focused on targeting hypermethylation. As a result, DNA hypomethylation-mediated abnormalities remained relatively less explored, and currently, there are no approved drugs that can be clinically used to target hypomethylation. Understanding the precise role of DNA hypomethylation is not only crucial from a mechanistic point of view but also for the development of pharmacological agents that can reverse the hypomethylated state of the DNA. This chapter focuses on the causes and impact of DNA hypomethylation in the development of cancer and describes the possible ways to pharmacologically target it, especially by using a naturally occurring physiologic agent S-adenosylmethionine (SAM).

Effect of Various Agents on the Direction of THP-1 Cell Differentiation

Abstract The ability of physiological (1α,25-dihydroxyvitamin D3, retinoic acid) and non-physiological (various LPS) agents and their combinations to influence the direction of promonocytic THP-1 cell differentiation was studied. The differentiating activity of the agents was evaluated by the expression and the ratio of surface receptors (TLR4, CD11b, and CD14) as well as by the change in THP-1 cell phagocytic activity of different degree of differentiation by Flow cytometry. The THP-1 cell differentiation by VD3 was shown to lead probably to the formation of classical monocytes. Summarizing we can conclude that VD3 induces the THP-1 cells differentiation with the formation of classical monocytes and the sequence of 1α, 25-dihydroxyvitamin D3 and non-toxic LPS R. capsulatus PG causes the THP-1 cells differentiation with the formation of inflammatory or intermediate monocytes.

Using NEURON for Reaction-Diffusion Modeling of Extracellular Dynamics.

Development of credible clinically-relevant brain simulations has been slowed due to a focus on electrophysiology in computational neuroscience, neglecting the multiscale whole-tissue modeling approach used for simulation in most other organ systems. We have now begun to extend the NEURON simulation platform in this direction by adding extracellular modeling. The extracellular medium of neural tissue is an active medium of neuromodulators, ions, inflammatory cells, oxygen, NO and other gases, with additional physiological, pharmacological and pathological agents. These extracellular agents influence, and are influenced by, cellular electrophysiology, and cellular chemophysiology—the complex internal cellular milieu of second-messenger signaling and cascades. NEURON's extracellular reaction-diffusion is supported by an intuitive Python-based where/who/what command sequence, derived from that used for intracellular reaction diffusion, to support coarse-grained macroscopic extracellular models. This simulation specification separates the expression of the conceptual model and parameters from the underlying numerical methods. In the volume-averaging approach used, the macroscopic model of tissue is characterized by free volume fraction—the proportion of space in which species are able to diffuse, and tortuosity—the average increase in path length due to obstacles. These tissue characteristics can be defined within particular spatial regions, enabling the modeler to account for regional differences, due either to intrinsic organization, particularly gray vs. white matter, or to pathology such as edema. We illustrate simulation development using spreading depression, a pathological phenomenon thought to play roles in migraine, epilepsy and stroke. Simulation results were verified against analytic results and against the extracellular portion of the simulation run under FiPy. The creation of this NEURON interface provides a pathway for interoperability that can be used to automatically export this class of models into complex intracellular/extracellular simulations and future cross-simulator standardization.

Phylogenetic diversity and antioxidant activities of culturable fungal endophytes associated with the mangrove species Rhizophora stylosa and R. mucronata in the South China Sea

Mangrove endophytic fungi can produce impressive quantities of metabolites with promising antioxidant activities that may be useful to humans as novel physiological agents. In this study, we investigated the phylogenetic diversity and antioxidant potential of 46 fungal endophytes derived from the mangrove species Rhizophora stylosa and R. mucronata from the South China Sea. The fungal isolates were identified using a combination of morphological characteristics and phylogenetic analysis of the internal transcribed spacer (ITS) sequences. Seventeen genera belonging to 8 taxonomic orders of Ascomycota were discovered, specifically, Botryosphaeriales, Capnodiales, Diaporthales, Eurotiales, Glomerellales, Hypocreales, Pleosporales, and Xylariales. The most abundant fungal orders included Xylariales (35.49%) and Diaporthales (27.61%), which were predominantly represented by the culturable species Pestalotiopsis sp. (34.54%) and Diaporthe sp. (18.62%). The stems showed more frequent colonization and species diversity than the roots, leaves, hypocotyls, and flower tissues of the host plant. The antioxidant activities of all the isolated fungal extracts on four different culture media were assessed using improved 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) methods. A relatively high proportion (84.8%) of the isolates displayed antioxidant capacity (%RSA > 50%). Further research also provided the first evidence that HQD-6 could produce flufuran as a significant radical scavenger with IC50 values of 34.85±1.56 and 9.75±0.58 μg/mL, respectively. Our findings suggest that the utilization of a biotope such as that of the endophytic fungal community thriving on the mangrove plants R. stylosa and R. mucronata may be suitable for use as a sustainable resource for natural antioxidants.

The Impact of T-2 Toxin on Vasoactive Intestinal Polypeptide-Like Immunoreactive (VIP-LI) Nerve Structures in the Wall of the Porcine Stomach and Duodenum.

T-2 toxin is a secondary metabolite of some Fusarium species. It is well-known that this substance can harmfully impact living organisms. Among others, thanks to the ability of crossing the blood–brain barrier, T-2 toxin can affect the central nervous system. Mycotoxins mostly get into the organism through the digestive tract; therefore, first of all they have to break the intestinal barrier, wherein the important component is the enteric nervous system (ENS). However, knowledge about the impact of T-2 toxin on the ENS is rather scant. As a result of the influence of various physiological and pathological agents, ENS can undergo adaptive and reparative processes which manifest as changes in the immunoreactivity of perikaryons for neuronal active substances. So, the aim of the present investigation was to study how low doses of T-2 toxin affect vasoactive intestinal polypeptide-like immunoreactive (VIP-LI) nervous structures in the ENS of the porcine stomach and duodenum. Obtained results have shown that T-2 toxin causes an percentage increase of VIP-LI nerve cells and nerve fibers in every enteric plexus in both fragments of gastrointestinal tract studied. This shows that even low doses of T-2 toxin can have an influence on living organisms.

Mechanisms of sphingosine-1-phosphate-mediated vasoconstriction of rat afferent arterioles.

Sphingosine-1-phosphate (S1P) influences resistance vessel function and is implicated in renal pathological processes. Previous studies revealed that S1P evoked potent vasoconstriction of the pre-glomerular microvasculature, but the underlying mechanisms remain incompletely defined. We postulated that S1P-mediated pre-glomerular microvascular vasoconstriction involves activation of voltage-dependent L-type calcium channels (L-VDCC) and the rho/rho kinase pathway. Afferent arteriolar reactivity was assessed in vitro using the blood-perfused rat juxtamedullary nephron preparation, and diameter was measured during exposure to physiological and pharmacological agents. Exogenous S1P (10-9 -10-5 mol L-1 ) evoked concentration-dependent vasoconstriction of afferent arterioles. Superfusion with nifedipine, a L-VDCC blocker, increased arteriolar diameter by 39 ± 18% of baseline and significantly attenuated the S1P-induced vasoconstriction. Superfusion with the rho kinase inhibitor, Y-27632, increased diameter by 60 ± 12% of baseline and also significantly blunted vasoconstriction by S1P. Combined nifedipine and Y-27632 treatment significantly inhibited S1P-induced vasoconstriction over the entire concentration range tested. In contrast, depletion of intracellular Ca2+ stores with the Ca2+ -ATPase inhibitors, thapsigargin or cyclopiazonic acid, did not alter the S1P-mediated vasoconstrictor profile. Scavenging reactive oxygen species (ROS) or inhibition of nicotinamide adenine dinucleotide phosphate oxidase activity significantly attenuated S1P-mediated vasoconstriction. Exogenous S1P elicits potent vasoconstriction of rat afferent arterioles. These data also demonstrate that S1P-mediated pre-glomerular vasoconstriction involves activation of L-VDCC, the rho/rho kinase pathway and ROS. Mobilization of Ca2+ from intracellular stores is not required for S1P-mediated vasoconstriction. These studies reveal a potential role for S1P in the modulation of renal microvascular tone.

Catalytic Asymmetric Synthesis of Butenolides and Butyrolactones.

γ-Butenolides, γ-butyrolactones, and derivatives, especially in enantiomerically pure form, constitute the structural core of numerous natural products which display an impressive range of biological activities which are important for the development of novel physiological and therapeutic agents. Furthermore, optically active γ-butenolides and γ-butyrolactones serve also as a prominent class of chiral building blocks for the synthesis of diverse biological active compounds and complex molecules. Taking into account the varying biological activity profiles and wide-ranging structural diversity of the optically active γ-butenolide or γ-butyrolactone structure, the development of asymmetric synthetic strategies for assembling such challenging scaffolds has attracted major attention from synthetic chemists in the past decade. This review offers an overview of the different enantioselective synthesis of γ-butenolides and γ-butyrolactones which employ catalytic amounts of metal complexes or organocatalysts, with emphasis focused on the mechanistic issues that account for the observed stereocontrol of the representative reactions, as well as practical applications and synthetic potentials.

Buffers Strongly Modulate Fibrin Self-Assembly into Fibrous Networks

Fibrin is a plasma protein with a central role in blood clotting and wound repair. Upon vascular injury, fibrin forms resilient fibrillar networks (clots) via a multistep self-assembly process, from monomers, to double-stranded protofibrils, to a branched network of thick fibers. In vitro, fibrin self-assembly is sensitive to physicochemical conditions like the solution pH and ionic strength, which tune the strength of the noncovalent driving forces. Here we report a surprising finding that the buffer—which is necessary to control the pH and is typically considered to be inert—also significantly influences fibrin self-assembly. We show by confocal microscopy and quantitative light scattering that various common buffering agents have no effect on the initial assembly of fibrin monomers into protofibrils but strongly hamper the subsequent lateral association of protofibrils into thicker fibers. We further find that the structural changes are independent of the molecular structure of the buffering agents as well as of the activation mechanism and even occur in fibrin networks formed from platelet-poor plasma. This buffer-mediated decrease in protofibril bundling results in a marked reduction in the permeability of fibrin networks but only weakly influences the elastic modulus of fibrin networks, providing a useful tuning parameter to independently control the elastic properties and the permeability of fibrin networks. Our work raises the possibility that fibrin assembly in vivo may be regulated by variations in the acute-phase levels of bicarbonate and phosphate, which act as physiological buffering agents of blood pH. Moreover, our findings add a new example of buffer-induced effects on biomolecular self-assembly to recent findings for a range of proteins and lipids.

Dual role of inflammatory mediators in cancer.

Inflammation is the body’s response to noxious stimuli such as infectious, physiological or chemical agents, it releases various inflammatory mediators via immune cells such as neutrophils, macrophages, and lymphocytes. These inflammatory mediators are growth factors, chemokines, and cytokines. Reactive oxygen species (ROS) and nitrogen species (RNS) activate transcriptional factors (NF-KB, STAT-3) and bring about cellular proliferation, genomic instability, angiogenesis, resistance to apoptosis, invasion, and metastasis. The presence of inflammatory mediators in the tumour microenvironment inhibits or promotes inflammation-induced cancer, depending on various stages of immune surveillance of the tumor i.e. by immunoediting, immunoprocessing, and immunoevasion. Myeloid derived suppressor cells are immature myeloid progenitor cells. They are the major immune-suppressor cells in the tumour inflammatory microenvironment that activate transcriptional factor NF-KB, STAT-3 to bring about tumour progression. Another gene which the micro RNA’s are noncoding RNA molecules is found to have a link with inflammation and cancer. This article discusses the roles of inflammatory mediators involved in antitumour or protumour activity within the context of the tumour microenvironment.

Role of topical dehydroepiandrosterone in ameliorating isotretinoin-induced Meibomian gland dysfunction in adult male albino rat

Isotretinoin broad effectiveness is limited by its detrimental effect on the Meibomian glands. Androgens have been reported to regulate the Meibomian gland function. Dehydroepiandrosterone (DHEA) is an androgen precursor considered as an efficient and physiological anti-ageing skin agent. This study aimed to investigate the role of the topical DHEA in ameliorating Meibomian gland dysfunction caused by isotretinoin employing different histological and immunohistochemical techniques. Twenty-four adult male albino rats were divided into four equal groups; control group, DHEA-treated group (1% twice daily for 3 months), isotretinoin-treated group (0.5mg/kg/day for 3 months), and both isotretinoin and DHEA-treated group. Meibomian gland specimens were processed for light microscopy. Immunohistochemical study was carried out using antibodies for proliferating cell nuclear antigen (PCNA), androgen receptor (AR) and estrogen receptor-alpha (ER-α). Sections from the isotretinoin-treated group revealed a reduction in the number and size of acini. Thickening and keratinization of the epithelial lining of the ducts were observed. Multiple degenerated acini and casts of acinar cells in the ducts of Meibomian glands were detected. Some dilated congested blood vessels and mononuclear cells were occasionally seen. A significant decrease in PAS reaction and a significant increase in collagen fiber content were detected. Immunohistochemical study revealed a significant increase in immunoexpression of PCNA in basal ductal cells coupled with decreased expression in basal acinar cells. Both AR and ER-α immunoexpression was significantly decreased. Minimal alterations were observed upon concomitant treatment with isotretinoin and DHEA as compared to the control group. Topical DHEA could prove to be beneficial in ameliorating isotretinoin-induced Meibomian gland dysfunction most probably through its androgenic effect.

Mechanisms of protection against irreversible oxidation of the catalytic cysteine of ALDH enzymes: Possible role of vicinal cysteines

The catalytic mechanism of the NAD(P)+-dependent aldehyde dehydrogenases (ALDHs) involves the nucleophilic attack of the essential cysteine (Cys302, mature HsALDH2 numbering) on the aldehyde substrate. Although oxidation of Cys302 will inactivate these enzymes, it is not yet well understood how this oxidation is prevented. In this work we explore possible mechanisms of protection by systematically analyzing the reported three-dimensional structures and amino acid sequences of the enzymes of the ALDH superfamily. Specifically, we considered the Cys302 conformational space, the structure and residues conservation of the catalytic loop where Cys302 is located, the observed oxidation states of Cys302, the ability of physiological reductants to revert its oxidation, and the presence of vicinal Cys in the catalytic loop. Our analyses suggested that: 1) In the apo-enzyme, the thiol group of Cys302 is quite resistant to oxidation by ambient O2 or mild oxidative conditions, because the protein environment promotes its high pKa. 2) NAD(P)+ bound in the “hydride transfer” conformation afforded total protection against Cys302 oxidation by an unknown mechanism. 3) If formed, the Cys302-sulfenic acid is protected against irreversible oxidation. 4) Of the physiological reductant agents, the dithiol lipoic acid could reduce a sulfenic or a disulfide bond in the ALDHs active site; glutathione cannot because its thiol group cannot reach Cys302, and other physiological monothiols may be ineffective in those ALDHs where their active site cannot sterically accommodate two molecules of the monothiols. 5) Formation of the disulfides Cys301-Cys302, Cys302-Cys304, Cys302-Cys305 and Cys-302-Cys306 in those ALDHs that have these Cys residues is not probable, because of the permitted Cys conformers as well as the conserved structure and low flexibility of the catalytic loop. 6) Only in some ALDH2, ALDH9, ALDH16 and ALDH23 enzymes, Cys303, alone or in conjunction with Cys301, allows disulfide formation. Interestingly, several of these enzymes are mitochondrial.

PLCζ is the physiological trigger of the Ca2+ oscillations that induce embryogenesis in mammals but conception can occur in its absence.

Activation of the egg by the sperm is the first, vital stage of embryogenesis. The sperm protein PLCζ has been proposed as the physiological agent that triggers the Ca2+ oscillations that normally initiate embryogenesis. Consistent with this, recombinant PLCζ induces Ca2+ oscillations in eggs and debilitating mutations in the PLCZ1 gene are associated with infertility in men. However, there has been no evidence that knockout of the gene encoding PLCζ abolishes the ability of sperm to induce Ca2+ oscillations in eggs. Here, we show that sperm derived from Plcz1-/- male mice fail to trigger Ca2+ oscillations in eggs, cause polyspermy and thus demonstrate that PLCζ is the physiological trigger of these Ca2+ oscillations. Remarkably, some eggs fertilized by PLCζ-null sperm can develop, albeit at greatly reduced efficiency, and after a significant time-delay. In addition, Plcz1-/- males are subfertile but not sterile, suggesting that in the absence of PLCζ, spontaneous egg activation can eventually occur via an alternative route. This is the first demonstration that in vivo fertilization without the normal physiological trigger of egg activation can result in offspring. PLCζ-null sperm now make it possible to resolve long-standing questions in fertilization biology, and to test the efficacy and safety of procedures used to treat human infertility.

Biosynthesis and biotransformation of bile acids

Bile acids are steroidal compounds, which contain 24 carbon atoms. They can be classified into two major groups: primary and secondary. The most abundant bile acids: The primary bile acids include cholic acid and chenodeoxycholic acid, while the major secondary bile acids are deoxycholic acid and litocholic acid. Bile acids are important physiological agents for intestinal absorption of nutrients and are used for biliary lipid secretion, toxic metabolites and xenobiotics. The aim of this paper is to analyze biosynthesis and biotransformation of bile acids, as preparation for practical usage in laboratory and clinical conditions. Topic: Biosynthesis and biotransformation of bile acids: The biosynthesis of bile acids is the dominant metabolic pathway for catabolism of cholesterol in humans. The classical route of biosynthesis of bile acids is embarking on the conversion of cholesterol into 7α-hydroxycholesterol using enzyme 7α-cholesterol hydroxylase (CYP7A1). This enzyme is one of the microsomal cytochrome P450 enzyme is localized exclusively in the liver. Classical road is the main road in the biosynthesis of bile acids, and its total contribution amounts to 90% for people, and 75% in mice. CYP 7A1 enzyme is considered to be sensitive to the inhibition of carbon monoxide, and the condition for the effect of NADPH, the oxygen, lecithin, and the NADPH-cytochrome P450 reductase. Bile acids are important signaling molecules and metabolic controls which activate the nuclear receptor and the G protein-coupled receptors (GPCR), a signaling lipid regulation of the liver, glucose and energy homeostasis. Also, bile acids maintain metabolic homeostasis. Biotransformation of bile acids: The conversion of cholesterol into bile acids just important for maintenance of cholesterol homeostasis, but also to prevent the accumulation of cholesterol, triglycerides and toxic metabolites as well as violations of the liver and other organs. Enterohepatic circulation of bile acids from the liver to the intestine and back to the liver occupies the most important role in the processes of absorption and distribution, as well as in metabolic regulation and homeostasis. Conclusions: This physiological process is complicated and regulates the membrane transport system in the liver and intestine by means of nuclear receptors. It is very dangerous fact that toxic bile acids may be causes of inflammation, apoptosis and cell death. On the other hand activated GPCR signaling and nuclear bile acid protects against inflammation of the liver, intestine and macrophages. Bile acid metabolism disorders cause cholestatic liver disease, dyslipidemia, fatty liver disease, cardiovascular disease and diabetes.

HOW RELIABLE ARE CALIBRATORS FOR URINARY MELATONIN SULFATE?

Melatonin is a versatile physiological agent that relating to the control of numerous physiologic processes owing to the multiplicity of sites of formation and the presence of melatonin receptors in various places of a human body. The melatonin metabolite 6-sulphatoxymelatonin (alias aMT6s or 6-SMT) infiltrates in urine. Therefore, there is a sense to find the sensitive and selective express-methods for the precise detection of melatonin metabolites in body fluids.The calibrators are proper tools for the signal processing. In the present research work that is the set of few calibers with well-defined concentrations of analyte. Comparison of the measured response of actual sample with reactions of calibers permits to interpret the real signal. Such a response can be either the transmittance or the optical density of sample that are measured by a photometer. The calibration of dose-response relation has been described by logistic Hill's curve with four parameters. The photometric transmittances of analyzed solutions were considered as the response. This paper describes the evaluation and comparison of sets of Hill's parameters for aMT6s-calibrators of independent producers. Reliable calibrators could help to simplify the analysis of urinary melatonin-sulfate dose. Such express-analysis could be more accessible in addition. Hence, the problem of creation of reliable calibrators is still unsolved and challenging.

Impact of reducing and oxidizing agents on the infectivity of Qβ phage and the overall structure of its capsid.

Qβ phages infect Escherichia coli in the human gut by recognizing F-pili as receptors. Infection therefore occurs under reducing conditions induced by physiological agents (e.g. glutathione) or the intestinal bacterial flora. After excretion in the environment, phage particles are exposed to oxidizing conditions and sometimes disinfection. If inactivation does not occur, the phage may infect new hosts in the human gut through the oral route. During such a life cycle, we demonstrated that, outside the human gut, cysteines of the major protein capsid of Qβ phage form disulfide bonds. Disinfection with NaClO does not allow overoxidation to occur. Such oxidation induces inactivation rather by irreversible damage to the minor proteins. In the presence of glutathione, most disulfide bonds are reduced, which slightly increases the capacity of the phage to infect E. coli in vitro Such reduction is reversible and barely alters infectivity of the phage. Reduction of all disulfide bonds by dithiothreitol leads to complete capsid destabilization. These data provide new insights into how the phages are impacted by oxidizing-reducing conditions outside their host cell and raises the possibility of the intervention of the redox during life cycle of the phage.

Fault bars in bird feathers: mechanisms, and ecological and evolutionary causes and consequences.

Fault bars are narrow malformations in feathers oriented almost perpendicular to the rachis where the feather vein and even the rachis may break. Breaks in the barbs and barbules result in small pieces of the feather vein being lost, while breaks in the rachis result in loss of the distal portion of the feather. Here, we provide a comprehensive review of 74 papers on fault bar formation in hopes of providing a clearer approach to their study. First, we review the evidence that the propensity to develop fault bars is modified by natural selection. Given that fault bars persist in the face of survival costs, we conclude that they must be an unfortunate consequence of some alternative adaptation that outweighs the fitness costs of fault bars. Second, we summarize evidence that the development of fault bars is triggered by psychological stress such as that of handling or predation attempts, and that they persist because the sudden contractions of the muscles in the feather follicle that control fright moults also causes the development of fault bars in growing feathers. Third, we review external and physiological (e.g. corticosterone) agents that may affect the likelihood that an acute stress will result in a growing feather exhibiting a fault bar. These modifying factors have often been treated as fundamental causes in the earlier literature on fault bars. Fourth, we then use this classification to propose a tentative model where fault bars of different severity (from light to severe) are the outcome of the interaction between the propensity to produce fault bars (which differs between species, individuals and feather follicles within individuals) and the intensity of the perturbation. This model helps to explain contradictory results in the literature, to identify gaps in our knowledge, and to suggest further studies. Lastly, we discuss ways in which better understanding of fault bars can inform us about other aspects of avian evolutionary ecology, such as the physiology of moult, the integration of moult into avian life cycles, and the strategies used to minimize stress during moult. Moreover, the study of fault bars may be relevant to understanding the aerodynamics of flight and the early evolution of flight.

Human Milk Oligosaccharides and Synthetic Galactosyloligosaccharides Contain 3′-, 4-, and 6′-Galactosyllactose and Attenuate Inflammation in Human T84, NCM-460, and H4 Cells and Intestinal Tissue Ex Vivo

Background: The immature intestinal mucosa responds excessively to inflammatory insult, but human milk protects infants from intestinal inflammation. The ability of galactosyllactoses [galactosyloligosaccharides (GOS)], newly found in human milk oligosaccharides (HMOS), to suppress inflammation was not known.Objective: The objective was to test whether GOS can directly attenuate inflammation and to explore the components of immune signaling modulated by GOS.Methods: Galactosyllactose composition was measured in sequential human milk samples from days 1 through 21 of lactation and in random colostrum samples from 38 mothers. Immature [human normal fetal intestinal epithelial cell (H4)] and mature [human metastatic colonic epithelial cell (T84) and human normal colon mucosal epithelial cell (NCM-460)] enterocyte cell lines were treated with the pro-inflammatory molecules tumor necrosis factor-α (TNF-α) or interleukin-1β (IL-1β) or infected with Salmonella or Listeria. The inflammatory response was measured as induction of IL-8, monocyte chemoattractant protein 1 (MCP-1), or macrophage inflammatory protein-3α (MIP-3α) protein by ELISA and mRNA by quantitative reverse transcriptase-polymerase chain reaction. The ability of HMOS or synthetic GOS to attenuate this inflammation was tested in vitro and in immature human intestinal tissue ex vivo.Results: The 3 galactosyllactoses (3′-GL, 4-GL, and 6′-GL) expressed in colostrum rapidly declined over early lactation (P < 0.05). In H4 cells, HMOS attenuated TNF-α– and IL-1β–induced expression of IL-8, MIP-3α, and MCP-1 to 48–51% and pathogen-induced IL-8 and MCP-1 to 26–30% of positive controls (P < 0.001). GOS reduced TNF-α– and IL-1β–induced inflammatory responses to 25–26% and pathogen-induced IL-8 and MCP-1 to 36–39% of positive controls (P < 0.001). GOS and HMOS mitigated nuclear translocation of nuclear transcription factor κB (NF-κB) p65. HMOS quenched the inflammatory response to Salmonella infection by immature human intestinal tissue ex vivo to 26% and by GOS to 50% of infected controls (P < 0.01).Conclusion: Galactosyllactose attenuated NF-κB inflammatory signaling in human intestinal epithelial cells and in human immature intestine. Thus, galactosyllactoses are strong physiologic anti-inflammatory agents in human colostrum and early milk, contributing to innate immune modulation. The potential clinical utility of galactosyllactose warrants investigation.