Why Do the Fetal Membranes Rupture Early after Fetoscopy? A Review

Iatrogenic preterm premature rupture of the fetal membranes (iPPROM) remains the Achilles’ heel of keyhole fetal surgery (fetoscopy) despite significant efforts in preclinical models to develop new therapies. This limited success is partially due to incomplete understanding why the fetal membranes rupture early after fetoscopy and notable differences in membrane physiology between humans and domestic species. In this review, we summarize aspects of fetoscopy that may contribute to iPPROM, the previous efforts to develop new therapies, and limitations of preclinical models commonly used in fetal membrane research.

Selective Antifungal Activity and Fungal Biofilm Inhibition of Tryptophan Center Symmetrical Short Peptide

Candida albicans, an opportunistic fungus, causes dental caries and contributes to mucosal bacterial dysbiosis leading to a second infection. Furthermore, C. albicans forms biofilms that are resistant to medicinal treatment. To make matters worse, antifungal resistance has spread (albeit slowly) in this species. Thus, it has been imperative to develop novel, antifungal drug compounds. Herein, a peptide was engineered with the sequence of RRFSFWFSFRR-NH2; this was named P19. This novel peptide has been observed to exert disruptive effects on fungal cell membrane physiology. Our results showed that P19 displayed high binding affinity to lipopolysaccharides (LPS), lipoteichoic acids (LTA) and the plasma membrane phosphatidylinositol (PI), phosphatidylserine (PS), cardiolipin, and phosphatidylglycerol (PG), further indicating that the molecular mechanism of P19 was not associated with the receptor recognition, but rather related to competitive interaction with the plasma membrane. In addition, compared with fluconazole and amphotericin B, P19 has been shown to have a lower potential for resistance selection than established antifungal agents.

Effect of high levels of CO2 and O2 on membrane fatty acid profile and membrane physiology of meat spoilage bacteria

The membrane is the major protective barrier separating the cell from the environment and is thus important for bacteria to survive environmental stress. This study investigates changes in membrane lipid compositions and membrane physiology of meat spoiling bacteria in response to high CO2 (30%) and O2 (70%) concentrations, as commonly used for modified atmosphere packaging of meat. Therefore, the fatty acid profile as well as membrane fluidity, permeability and cell surface were determined and correlated to the genomic settings of five meat spoiling bacteria Brochothrix (B.) thermosphacta, Carnobacterium (C.) divergens, C. maltaromaticum, Leuconostoc (L.) gelidum subsp. gelidum and L. gelidum subsp. gasicomitatum cultivated under different gas atmospheres. We identified different genomic potentials for fatty acid adaptations, which were in accordance with actual measured changes in the fatty acid composition for each species in response to CO2 and/or O2, e.g., an increase in saturated, iso and cyclopropane fatty acids. Even though fatty acid changes were species-specific, the general physiological responses were similar, comprising a decreased membrane permeability and fluidity. Thus, we concluded that meat spoiling bacteria facilitate a change in membrane fatty acids upon exposure to O2 and CO2, what leads to alteration of membrane fluidity and permeability. The observed adaptations might contribute to the resistance of meat spoilers against detrimental effects of the gases O2 and CO2 and thus help to explain their ability to grow under different modified atmospheres. Furthermore, this study provides fundamental knowledge regarding the impact of fatty acid changes on important membrane properties of bacteria.

Cor triatriatum sinistrum diagnosed in the adulthood: a systematic review

BackgroundWe performed a systematic review of cor triatriatum sinistrum (CTS) diagnosed in adults. The aim of this review was to describe the clinical presentation, natural history and management of this congenital heart disease.MethodsA PubMed literature search for ‘cor triatriatum sinistrum’ published since 2005 was performed. Included patients were divided into those with and without obstructive membrane physiology. The clinical course differences were compared.ResultsA total of 171 published cases were included. The median age at diagnosis was 43 years (IQR, 30–60). Obstructive membrane physiology was observed in 70 (41%), and this patient group was younger at presentation (median age 39 (IQR, 28–52) vs 50 years (IQR, 32–64), p=0.003).Patients with obstructive membrane more frequently had associated cardiac defects (58.6% vs 42.4%, p=0.039). Overall, the most frequent clinical symptom was atrial fibrillation, as this was present in 56 (32.8%) of all patients. CTS-related symptoms were more frequent in patients with obstructive membrane: congestive heart failure (44.3% vs 15.2%, p<0.001), pulmonary hypertension (27.1% vs 6.1%, p<0.001), haemorrhage (8.6% vs 0%, p=0.004) and infections manifestation (8.6% vs 0%, p=0.004).A total of 71 (41.5%) patients with CTS required interventional treatment, mainly within patients with the obstructive membrane (86.8% vs 12.6%, p<0.001).ConclusionThe natural history of CTS most often manifests with symptoms of congestive heart failure. Patients with obstructive membrane most often have associated cardiac defects and higher risk for infections and haemorrhage. The interventional treatment of CTS remains the first choice for obstructive membrane.

Lipidomic and biophysical homeostasis of mammalian membranes in response to dietary lipids is essential for cellular fitness

ABSTRACTBiological membranes form the functional, dynamic interface that hosts a major fraction of all cellular bioactivity. Proper membrane physiology requires maintenance of a narrow range of physicochemical properties, which must be buffered from external perturbations. While homeostatic adaptation of membrane fluidity to temperature variation is a ubiquitous design feature of ectothermic organisms, such responsive membrane adaptation to external inputs has not been directly observed in mammals. Here, we report that challenging mammalian membrane homeostasis by dietary lipids leads to robust lipidomic remodeling to preserve membrane physical properties. Specifically, exogenous polyunsaturated fatty acids (PUFAs) are rapidly and extensively incorporated into membrane lipids, inducing a reduction in membrane packing. These effects are rapidly compensated both in culture and in vivo by lipidome-wide remodeling, most notably upregulation of saturated lipids and cholesterol. These lipidomic changes result in recovery of membrane packing and permeability. This lipidomic and biophysical compensation is mediated in part by lipid regulatory machinery, whose pharmacological or genetic abrogation results in cytotoxicity when membrane homeostasis is challenged by dietary lipids. These results reveal an essential mammalian mechanism for membrane homeostasis wherein lipidome remodeling in response to dietary lipid inputs preserves functional membrane phenotypes.

Mammalian Cell Entry domains are required for bile resistance and virulence inSalmonella

MCE domains were first reported inMycobacteriaas having a role inMammalianCellEntry, with subsequent studies showing their importance during infection. Here, we have examined the function of MCE proteins inSalmonellaTyphimurium during mammalian infection. We report that MCE proteins are required forSalmonellavirulence, but that this is not related to decreased adherence, entry or survival in mammalian cells. Instead, we reveal that MCE proteins are required forSalmonellabile resistance, in particular to withstand bile salts such as cholate and deoxycholate. Based on our previous work inEscherichia coli, and other studies that have reported roles for MCE proteins in membrane biogenesis, we propose thatSalmonellalacking MCE domains have a defective outer membrane that results in bile sensitivity and decreased virulencein vivo. These results suggest that MCE domains mediate fundamental aspects of bacterial membrane physiology as opposed to a proposed direct role in mammalian cell entry, explaining their conservation across both pathogenic and non-pathogenic bacteria.