A transcriptional switch controls sex determination in Plasmodium falciparum.

Sexual reproduction and meiotic sex are deeply rooted in the eukaryotic tree of life, but mechanisms determining sex or mating types are extremely varied and are only well characterized in a few model organisms1. In malaria parasites, sexual reproduction coincides with transmission to the vector host. Sex determination is non-genetic, with each haploid parasite capable of producing either a male or a female gametocyte in the human host2. The hierarchy of events and molecular mechanisms that trigger sex determination and maintenance of sexual identity are yet to be elucidated. Here we show that the male development 1 (md1) gene is both necessary and sufficient for male fate determination in the human malaria parasite Plasmodium falciparum. We show that Md1 has a dual function stemming from two separate domains: in sex determination through its N terminus and in male development from its conserved C-terminal LOTUS/OST-HTH domain. We further identify a bistable switch at the md1 locus, which is coupled with sex determination and ensures that the male-determining gene is not expressed in the female lineage. We describe one of only a few known non-genetic mechanisms of sex determination in a eukaryote and highlight Md1 as a potential target for interventions that block malaria transmission.

The natural history of gastro-esophageal reflux disease: a comprehensive review.

Gastroesophageal reflux disease (GERD) is a common disorder of the upper gastrointestinal tract which is typically characterized by heartburn and acid regurgitation. These symptoms are widespread in the community and range from 2.5% to more than 25%. Economic analyses showed an increase in direct and indirect costs related to the diagnosis, treatment and surveillance of GERD and its complications. The aim of this review is to provide current information regarding the natural history of GERD, taking into account the evolution of its definition and the worldwide gradual change of its epidemiology. Present knowledge shows that there are two main forms of GERD, that is erosive reflux disease (ERD) and non-erosive reflux disease (NERD) and the latter comprises the majority of patients (up to 70%). The major complication of GERD is the development of Barrett esophagus, which is considered as a pre-cancerous lesion. Although data from medical literature on the natural history of this disease are limited and mainly retrospective, they seem to indicate that both NERD and mild esophagitis tend to remain as such with time and the progression from NERD to ERD, from mild to severe ERD and from ERD to Barrett's esophagus may occur in a small proportion of patients, ranging from 0 to 30%, 10 to 22% and 1 to 13% of cases, respectively. It is necessary to stress that these data are strongly influenced by the use of powerful antisecretory drugs (PPIs). Further studies are needed to better elucidate this matter and overcome the present limitations represented by the lack of large prospective longitudinal investigations, absence of homogeneous definitions of the various forms of GERD, influence of different treatments, clear exclusion of patients with functional disorders of the esophagus.

Effect of a fungal chitosan preparation on Brettanomyces bruxellensis, a wine contaminant.

AIM: To investigate the action mechanisms of a specific fungal origin chitosan preparation on Brettanomyces bruxellensis. METHODS AND RESULTS: Different approaches in a wine-model synthetic medium were carried out: optical and electronic microscopy, flow cytometry, ATP flow measurements and zeta potential characterization. The inactivation effect was confirmed. Moreover, fungal origin chitosan induced both physical and biological effects on B. bruxellensis cells. Physical effect led to aggregation of cells with chitosan likely due to charge interactions. At the same time, a biological effect induced a leakage of ATP and thus a viability loss of B. bruxellensis cells. CONCLUSIONS: The antimicrobial action mode of chitosan against B. bruxellensis is not a simple mechanism but the result of several mechanisms acting together. SIGNIFICANCE AND IMPACT OF THE STUDY: Brettanomyces bruxellensis, a yeast responsible for the production of undesirable aromatic compounds (volatile phenols), is a permanent threat to wine quality. Today, different means are implemented to fight against B. bruxellensis, but are not always sufficient. The chitosan of fungal origin is introduced as a new tool to control B. bruxellensis in winemaking and has poorly been studied before for this application.

[Immune tolerance and control of CNS autoimmunity: from animal models to MS patients]. / Tolérance immunitaire vis-à-vis d'auto-antigènes du système nerveux: implications thérapeutiques.

INTRODUCTION: Multiple sclerosis (MS) is a chronic inflammatory disease resulting in demyelination and axonal loss within the central nervous system (CNS). An autoimmune reaction directed against CNS antigens contributes to the disease process. Since the CNS has long been considered as an immune privileged site, how such an immune response can develop locally has remained enigmatic. Recent data, mostly based on the study of animal models for MS, have shown that the CNS is in fact more permissive to the development of immune responses than previously thought. This observation is counterbalanced by the fact that immune tolerance to neural antigens can be induced outside the CNS. This review focuses on the mechanisms preventing CNS autoimmunity, which act in three separate tissues. STATE OF THE ART: In the thymus, expression of CNS auto-antigens promotes partial protection, notably through elimination of autoreactive T cells. In the secondary lymphoid organs, the remaining autoreactive T cells are kept under control by the thymus-derived naturally occurring regulatory T cells of the CD4(+) Foxp3(+) phenotype. In the CNS, multiple mechanisms including the local activation of regulatory T cells further limit autoimmunity. CONCLUSIONS AND PERSPECTIVES: A better understanding of the induction of regulatory T cells, of their mechanisms of action, and of approaches to manipulate them in vivo may offer new therapeutic opportunities for MS patients.

The GerdQ questionnaire and high resolution manometry support the hypothesis that proton pump inhibitor-responsive oesophageal eosinophilia is a GERD-related phenomenon.

BACKGROUND: Little is known about the relationship between proton pump inhibitor-responsive oesophageal eosinophilia (PPI-REE), eosinophilic esophagitis (EoE) and gastro-oesophageal reflux disease (GERD). AIM: To compare high resolution manometry features and symptom profiles of patients with EoE, PPI-REE and GERD. METHODS: Consecutive patients diagnosed with EoE or PPI-REE according to international criteria (presence of at least one typical symptom of oesophageal dysfunction; at least 15 eosinophils per high-power field at mid/proximal oesophagus, persistence or resolution of eosinophils after an 8-week PPI trial), and a group of patients with proven GERD and oesophageal eosinophilia, prospectively completed the GerdQ questionnaire and underwent high resolution manometry. RESULTS: Thirty-five patients with EoE, 17 with PPI-REE and 27 with GERD were enrolled. When compared to GERD, both EoE and PPI-REE had higher rates of dysphagia (15% vs. 94% vs. 88%, P < 0.0001), patients with EoE reported heartburn and regurgitation less frequently (26% vs. 85%, and 17% vs. 74%, respectively; P < 0.001 for each and had lower GerdQ score [1 (0-6) vs. 8 (6-12), P < 0.001] than GERD patients. There was no significant difference comparing PPI-REE and GERD patients. Patients with PPI-REE had a higher prevalence of erosive oesophagitis than patients with EoE (35% vs. 9%, P = 0.04), which was similar to that of GERD (48%, P = 0.54). Patients with EoE had a lower frequency of high resolution manometry features associated with GERD than patients with PPI-REE. There was no significant difference between PPI-REE and GERD patients. CONCLUSION: GERD, as assessed by GerdQ and high resolution manometry is common in patients with PPI-REE, which may share similar pathogenic mechanisms.

Esophagogastric junction contractility for clinical assessment in patients with GERD: a real added value?

BACKGROUND: The role of esophagogastric junction contractile integral (EGJ-CI) as assessed by high-resolution manometry (HRM) is unclear. We aimed to correlate the EGJ-CI with impedance-pH findings in gastro-esophageal reflux disease (GERD) patients. METHODS: Consecutive patients with GERD symptoms were enrolled. All patients underwent upper endoscopy, HRM, and impedance-pH testing. The EGJ-CI was calculated using the distal contractile integral tool box during three consecutive respiratory cycles. The value was then divided by the duration of these cycles. A value below 13 was considered as a defective EGJ-CI. We also assessed EGJ morphology, esophageal acid exposure time (AET), number of reflux episodes (NRE), and symptom association analysis (SAA). A positive impedance-pH monitoring was considered in case of abnormal AET and/or NRE and/or positive SAA. KEY RESULTS: Among 130 patients we enrolled, 91 had GERD (abnormal AET and/or elevated NRE and/or positive SAA) and 39 had functional heartburn (FH) (negative endoscopy, normal AET, normal NRE, and negative SAA). The GERD patients had a lower median value of EGJ-CI (11 [3.1-20.7] vs 22 [9.9-41], p < 0.02) compared to FH patients. Patients with a defective EGJ-CI had, more frequently, a positive impedance-pH monitoring or esophageal mucosal lesions at endoscopy (p < 0.05 and p < 0.05, respectively) than patients with a normal EGJ-CI. An EGJ-CI cut-off value of 5 mmHg cm yielded the optimal performance in identifying GERD at impedance-pH (sensitivity 89%-specificity 63%). CONCLUSIONS & INFERENCES: A defective EGJ-CI at HRM is clearly associated with evidence of GERD at impedance-pH monitoring. Evaluating EGJ-CI may be useful to predict an abnormal impedance-pH testing.

Esophagogastric junction morphology is associated with a positive impedance-pH monitoring in patients with GERD.

BACKGROUND: High-resolution manometry (HRM) provides information on esophagogastric junction (EGJ) morphology, distinguishing three different subtypes. Data on the correlation between EGJ subtypes and impedance-pH detected reflux patterns are lacking. We aimed to correlate the EGJ subtypes with impedance-pH findings in patients with reflux symptoms. METHODS: Consecutive patients with suspected gastroesophageal reflux disease (GERD) were enrolled. All patients underwent HRM and impedance-pH testing off-therapy. EGJ was classified as: Type I, no separation between the lower esophageal sphincter (LES) and crural diaphragm (CD); Type II, minimal separation (>1 and <2 cm); Type III, ≥ 2 cm separation. We measured esophageal acid exposure time (AET), number of total reflux episodes and symptom association analysis. KEY RESULTS: We enrolled 130 consecutive patients and identified 46.2% Type I EGJ, 38.5% Type II, and 15.4% Type III patients. Type III subjects had a higher number of reflux episodes (61 vs 45, p < 0.03, vs 25, p < 0.001), a greater mean AET (12.4 vs 4.2, p < 0.02, vs 1.5, p < 0.001) and a greater positive symptom association (75% vs 72%, p = 0.732 vs 43.3%, p < 0.02) compared with Type II and I patients, respectively. Furthermore, Type II subjects showed statistically significant (overall p < 0.01) increased reflux when compared with Type I patients. Type III and II EGJ morphologies had a more frequent probability to show a positive multichannel intraluminal impedance pH monitoring than Type I (95% vs 84% vs 50%, p < 0.001). CONCLUSIONS & INFERENCES: Increasing separation between LES and CD can cause a gradual and significant increase in reflux. EGJ morphology may be useful to estimate an abnormal impedance-pH testing in GERD patients.

ACE inhibition prevents diastolic Ca2+ overload and loss of myofilament Ca2+ sensitivity after myocardial infarction.

Prevention of adverse cardiac remodeling after myocardial infarction (MI) remains a therapeutic challenge. Angiotensin-converting enzyme inhibitors (ACE-I) are a well-established first-line treatment. ACE-I delay fibrosis, but little is known about their molecular effects on cardiomyocytes. We investigated the effects of the ACE-I delapril on cardiomyocytes in a mouse model of heart failure (HF) after MI. Mice were randomly assigned to three groups: Sham, MI, and MI-D (6 weeks of treatment with a non-hypotensive dose of delapril started 24h after MI). Echocardiography and pressure-volume loops revealed that MI induced hypertrophy and dilation, and altered both contraction and relaxation of the left ventricle. At the cellular level, MI cardiomyocytes exhibited reduced contraction, slowed relaxation, increased diastolic Ca2+ levels, decreased Ca2+-transient amplitude, and diminished Ca2+ sensitivity of myofilaments. In MI-D mice, however, both mortality and cardiac remodeling were decreased when compared to non-treated MI mice. Delapril maintained cardiomyocyte contraction and relaxation, prevented diastolic Ca2+ overload and retained the normal Ca2+ sensitivity of contractile proteins. Delapril maintained SERCA2a activity through normalization of P-PLB/PLB (for both Ser16- PLB and Thr17-PLB) and PLB/SERCA2a ratios in cardiomyocytes, favoring normal reuptake of Ca2+ in the sarcoplasmic reticulum. In addition, delapril prevented defective cTnI function by normalizing the expression of PKC, enhanced in MI mice. In conclusion, early therapy with delapril after MI preserved the normal contraction/relaxation cycle of surviving cardiomyocytes with multiple direct effects on key intracellular mechanisms contributing to preserve cardiac function.

High affinity RGD-binding sites at the plasma membrane of Arabidopsis thaliana links the cell wall.

The heptapeptide Tyr-Gly-Arg-Gly-Asp-Ser-Pro containing the sequence Arg-Gly-Asp (RGD--the essential structure recognised by animal cells in substrate adhesion molecules) was tested on epidermal cells of onion and cultured cells of Arabidopsis upon plasmolysis. Dramatic changes were observed on both types of cells following treatment: on onion cells, Hechtian strands linking the cell wall to the membrane were lost, while Arabidopsis cells changed from concave to convex plasmolysis. A control heptapeptide Tyr-Gly-Asp-Gly-Arg-Ser-Pro had no effect on the shape of plasmolysed cells. Protoplasts isolated from Arabidopsis cells agglutinate in the presence of ProNectinF, a genetically engineered protein of 72 kDa containing 13 RGD sequences: several protoplasts may adhere to a single molecule of ProNectinF. The addition of the RGD-heptapeptide disrupted the adhesion between the protoplasts. Purified plasma membrane from Arabidopsis cells exhibits specific binding sites for the iodinated RGD-heptapeptide. The binding is saturable, reversible, and two types of high affinity sites (Kd1 approximately 1 nM, and Kd2 approximately 40 nM) can be discerned. Competitive inhibition by several structurally related peptides and proteins noted the specific requirement for the RGD sequence. Thus, the RGD-binding activity of Arabidopsis fulfils the adhesion features of integrins, i.e. peptide specificity, subcellular location, and involvement in plasma membrane-cell wall attachments.

Isolation, purification and primary structure of insulin from the turtle Chrysemys dorbigni.

Insulin A and B chains from pancreas of the turtle Chrysemys dorbigni have been purified to homogeneity, and their primary structures have been determined. The sequence of the A chain is G-I-V-E-Q-C-C-H-N-T-C-S-L-Y-Q-L-E-N-Y-C-N, and that of the B chain is A-A-N-Q-H-L-C-G-S-H-L-V-E-A-L-Y-L-V-C-G-E-R-G-F-F-Y-S-P-K-A. The amino acid sequence of Chrysemys insulin is identical to that of another turtle (Pseudemys scripta), the chicken, and turkey. When compared with alligator insulin, it has three conservative substitutions in the B chain. However, there are seven substitutions when compared with the insulin of the rattlesnake.