Correction: Prevalence and associated risk factors for mental health problems among patients with polycystic ovary syndrome in Bangladesh: A nationwide cross-sectional study.

[This corrects the article DOI: 10.1371/journal.pone.0270102.].

Effect of charge on the antimicrobial activity of alpha-helical amphibian antimicrobial peptide.

Antibiotic resistance is a severe threat to the world's public health, which has increased the need to discover novel antibacterial molecules. In this context, an emerging class of naturally occurring short peptide molecules called antimicrobial peptides (AMPs) has been considered potent antibacterial agents. Amphibians are one of the significant sources of AMPs, which have been extensively studied for the last few decades. Most amphibian AMPs are cationic, and several of these cationic AMPs adopt a well-defined alpha-helical structure in the presence of bacterial membranes. These cationic alpha-helical amphibian AMPs (CαAMPs) can selectively and preferentially bind with the negatively charged surfaces of Gram-positive and Gram-negative bacteria through electrostatic interaction, considered the main reason for their antibacterial activities. Here, we categorized these CαAMPs according to their charge, and to calculate the charge density; we divided the charge of each peptide by its corresponding length. To investigate the effect of charge among these categories, charge or charge density under each charge category was plotted against their corresponding minimum inhibitory concentration (MIC). Moreover, the effect of charge modification of some CαAMPs under specific charge categories in the context of MIC and hemolysis was also discussed. The information in this review will help us understand the antibacterial activity of accessible CαAMPs depending on each charge category across species. Additionally, this study suggests that designing novel functional antibacterial agents requires charge modification optimally.

Analgesic and Sedative-Hypnotic Potentiality of Crude Methanolic Extract of Gomphandra tetrandra (Wall.) Sleumer Leaves.

Objectives: Gomphandra tetrandra (Wall.) Sleumer (leaves) belonging to the family Stemonuraceae was investigated for preliminary phytochemical screening and evaluating their pharmacological activities in various pharmacological models. Materials and Methods: The crude methanolic extract was screened with different chemical reagents for the qualitative detection of different phytochemical groups. The peripheral analgesic function was determined using the acetic acid-induced writhing procedure and sedative-hypnotic behaviors were assessed using hole-board, open field, and hole-cross tests using different doses of the extract (200 mg/kg and 400 mg/kg body weight). Results: Phytochemical screening revealed that methanolic extract of G. tetranda leaves contains steroids, gums, mucilages, phytosterols, carbohydrates, and flavonoids. The crude methanolic extract at 200 mg/kg and 400 mg/kg doses showed statistically significant activity in acetic acid-induced writhing inhibition test with 60% (p<0.01) and 76.47% (p<0.01) inhibition, respectively, compared to control. The extract also had dose-dependent substantial (p<0.01) sedative-hypnotic activities compared with diazepam in the hole-board, open field, and hole-cross tests. Conclusion: It may be assumed that the methanolic leaf extract of G. tetrandra possesses a strong possibility of having analgesic and sedative-hypnotic activity due to the presence of bioactive compounds in its leaves. Moreover, observed results have opened a new era of in-depth research to discover the possible mechanism of analgesic and sedative-hypnotic activity.

Role of interfacial hydrophobicity in antimicrobial peptide magainin 2-induced nanopore formation.

Antimicrobial peptide magainin 2 (Mag) forms nanopores in lipid bilayers and induces membrane permeation of the internal contents from vesicles. The binding of Mag to the membrane interface of a giant unilamellar vesicle (GUV) increases its fractional area change, δ, which is one of the main causes of Mag-induced nanopore formation. However, the role of its amino acid composition in the Mag-induced area increase and the following nanopore formation is not well understood. Here, to elucidate it we examined the role of interfacial hydrophobicity of Mag in its nanopore formation activity by investigating de novo-designed Mag mutants-induced nanopore formation in GUVs. Aligned amino acid residues in the α-helix of Mag were replaced to create 3 mutants: F5A-Mag, A9F-Mag, and F5,12,16A-Mag. These mutants have different interfacial hydrophobicity due to the variation of the numbers of Phe and Ala because the interfacial hydrophobicity of Phe is higher than that of Ala. The rate constant of Mag mutant-induced nanopore formation, kp, increased with increasing numbers of Phe residues at the same peptide concentration. Further, the Mag mutant-induced δ increased with increasing numbers of Phe residues at the same peptide concentration. These results indicate that kp and δ increase with increasing interfacial hydrophobicity of Mag mutants. The relationship between kp and δ in the Mag and its mutants clearly indicates that kp increases with increasing δ, irrespective of the difference in mutants. Based on these results, we can conclude that the interfacial hydrophobicity of Mag plays an important role in its nanopore formation activity.

Comparative evaluation of authorized drugs for treating Covid-19 patients.

Background and Aims: Vaccines are the first line of defense against coronavirus disease 2019 (Covid-19). However, the antiviral drugs provide a new tool to fight the Covid-19 pandemic. Here we aimed for a comparative evaluation of authorized drugs for treating Covid-19 patients. Methods: We searched in PubMed and Google Scholar using keywords and terms such as Covid, SARS-CoV-2, Coronavirus disease 2019, therapeutic management, hospitalized Covid-19 patients, Covid-19 treatment. We also gathered information from reputed newspapers, web portals, and websites. We thoroughly observed, screened, and included the studies relevant to our inclusion criteria. We included only the United States Food and Drug Administration (FDA) authorized drugs for this review. Results: We found that molnupiravir and paxlovid are available for oral use, and remdesivir is for only hospitalized patients. Paxlovid is a combination of nirmatrelvir and ritonavir, nirmatrelvir is a protease inhibitor (ritonavir increases the concentration of nirmatrelvir), and the other two (remdesivir and molnupiravir) are nucleoside analog prodrugs. Remdesivir and molnupiravir doses do not need to adjust in renal and hepatic impairment. However, the paxlovid dose adjustment is required for mild to moderate renal or hepatic impaired patients. Also, the drug is not allowed for Covid-19 patients with severe renal or hepatic impairment. Preliminary studies showed oral antiviral drugs significantly reduce hospitalization or death among mild to severe patients. Moreover, the US FDA has approved four monoclonal antibodies for Covid-19 treatment. Studies suggest that these drugs would reduce the risk of hospitalization or severity of symptoms. World Health Organization strongly recommended the use of corticosteroids along with other antiviral drugs for severe or critically hospitalized patients. Conclusion: All authorized drugs are effective in inhibiting viral replication for most SARS-CoV-2 variants. Therefore, along with vaccines, these drugs might potentially aid in fighting the Covid-19 pandemic.

Prevalence and associated risk factors for mental health problems among patients with polycystic ovary syndrome in Bangladesh: A nationwide cross-Sectional study.

BACKGROUND: Polycystic ovary syndrome (PCOS) is a common female reproductive endocrine problem worldwide. The prevalence of mental disorder is increasing among PCOS patients due to various physical, psychological, and social issues. Here we aimed to evaluate the mental health and associated factors among women suffering from PCOS in Bangladesh. METHODS: We performed an online cross-sectional survey among 409 participants with PCOS using Google Forms. We used structured questionnaires to collect socio-demographic information and lifestyle-related factors. Also, we applied patient health questionnaire (PHQ-9), generalized anxiety disorder (GAD-7) scale, and UCLA loneliness (UCLA-3) scale for psychometric assessment of the participants. Finally, we applied several statistical tools and performed data interpretations to evaluate the prevalence of mental health disorders and associated factors among patients with PCOS in Bangladesh. RESULTS: Prevalence of loneliness, generalized anxiety disorder and depressive illness among the women with PCOS were 71%, 88%, and 60%, respectively. Among the mental illness, mild, moderate, and severe cases were 39%, 18%, and 14% for loneliness; 39%, 23% and 26% for generalized anxiety disorder; and 35%, 18%, and 7% for depressive disorder. According to the present findings, obesity, financial condition, physical exercise, mealtime, food habit, daily water consumption, birth control method, and long-term oral contraceptive pills contribute to developing mental health disorders among females with PCOS in Bangladesh. CONCLUSION: According to present study results, high proportion of women suffering from PCOS experience several mental disorders in Bangladesh. Although several socio-demographic and lifestyle-related factors were found to be associated with the poor mental health of women with PCOS; however, PCOS itself is a condition that favors poor physical and psychological health. Therefore, we recommend proper treatment, public awareness, and a healthy lifestyle to promote the good mental health of women suffering from PCOS.

The COVID-19 vaccination experience in Bangladesh: Findings from a cross-sectional study.

OBJECTIVES: Vaccination rollout against COVID-19 has started in developed countries in early December 2020. Mass immunization for poor or low-income countries is quite challenging before 2023. Being a lower-middle-income country, Bangladesh has begun a nationwide COVID-19 vaccination drive in early February 2021. Here, we aimed to assess the opinions, experiences, and adverse events of the COVID-19 vaccination in Bangladesh. METHODS: We conducted this online cross-sectional study from 10 February 2021, to 10 March 2021, in Bangladesh. A self-reported semi-structured survey questionnaire was used using Google forms. We recorded demographics, disease history, medication records, opinions and experiences of vaccination, and associated adverse events symptoms. RESULTS: We observed leading comorbid diseases were hypertension (25.9%), diabetes (21.1%), heart diseases (9.3%), and asthma (8.7%). The most frequently reported adverse events were injection site pain (34.3%), fever (32.6%), headache (20.2%), fatigue (16.6%), and cold feeling (15.4%). The chances of having adverse events were significantly higher in males than females (p = 0.039). However, 36.4% of respondents reported no adverse events. Adverse events usually appeared after 12 h and went way within 48 h of vaccination. Besides, 85.5% were happy with the overall vaccination management, while 88.0% of the respondents recommended the COVID-19 vaccine for others for early immunization. CONCLUSION: According to the present findings, reported adverse events after the doses of Covishield in Bangladesh were non-serious and temporary. In Bangladesh, the early vaccination against COVID-19 was possible due to its prudent vaccine deal, previous mass vaccination experience, and vaccine diplomacy.

Effect of membrane potential on pore formation by the antimicrobial peptide magainin 2 in lipid bilayers.

The effect of membrane potential on plasma membrane damage generated by antimicrobial peptides (AMPs) is an important, yet poorly characterized, process. Here, we studied the effect of membrane potential (φm) on pore formation by magainin 2 (Mag) in single giant unilamellar vesicles (GUVs) composed of dioleoylphosphatidylglycerol (DOPG)/dioleoylphosphatidylcholine (DOPC) membranes. Various membrane potentials in GUVs containing gramicidin A were generated as a result of K+ concentration gradients. First, we examined Mag-generated membrane permeation of the water-soluble fluorescent probe calcein in single DOPG/DOPC-GUVs in the presence of membrane potential. The results indicate that the rate constant (kp) of Mag-induced pore formation increased with increasing negative membrane potentials. Analysis of the rim intensity of single GUVs interacting with low concentrations of a fluorescent probe, carboxyfluorescein-labeled Mag (CF-Mag), using confocal laser scanning microscopy (CLSM) shows that the concentration of CF-Mag in the membrane greatly increased with negative membrane potentials. This indicates that the binding constant of CF-Mag to the membrane increased with more negative membrane potentials. To elucidate the location of Mag in a GUV with φm during Mag-induced pore formation, we examined the interaction of Mag and a low concentration of a CF-Mag mixture with single GUVs containing the water-soluble fluorescent probe AF647 using CLSM. The data indicate that CF-Mag locates in the external leaflet of single GUVs until just before pore formation. Based on these data, we conclude that the increase in the surface concentration of Mag is one of the primary causes of the increase in kp with negative membrane potential.

Effect of Transmembrane Asymmetric Distribution of Lipids and Peptides on Lipid Bilayers.

The transbilayer asymmetry of the biomembrane is generated due to the differences in lipid and protein compositions between two leaflets, which plays important roles in physiological functions. However, transbilayer asymmetry can also be originated due to a nonequal number of lipids or proteins in each leaflet, which has not been well recognized. Therefore, to shed light on this field, here we generated theoretical models for the effect of transbilayer asymmetry originated from the differences in the number of lipids and peptides in each leaflet on the state of lipid bilayers. The first model described the effect of asymmetric lipid distribution on the state of lipid bilayers. We obtained theoretical equations for the fractional change in area per lipid in both leaflets as a function of the ratio of the number of lipids in each leaflet, which agreed with the molecular dynamics simulation results quantitatively. Results indicated that tensions in both leaflets are opposite in direction, and their magnitude is the same. We also performed experiments on the effect of lipid insertion in the outer leaflet on the fractional change in area per lipid. These results agreed quantitatively with the values predicted by the above model. The second model described the effect of asymmetric distribution of peptides on the state of lipid bilayers. We obtained theoretical equations for the area per lipid in both leaflets as a function of the surface concentration of peptides located only in the outer leaflet, which agreed with the results of the antimicrobial peptide magainin 2-induced area change.

The role of membrane tension in the action of antimicrobial peptides and cell-penetrating peptides in biomembranes.

For antimicrobial peptides (AMPs) with antimicrobial and bactericidal activities and cell-penetrating peptides (CPPs) with activity to permeate through plasma membrane, their interactions with lipid bilayer region in plasma membrane play important roles in these functions. However, the elementary processes and mechanisms of their functions have not been clear. The single giant unilamellar vesicle (GUV) method has revealed the details of elementary processes of interaction of some AMPs and CPPs with lipid vesicles. In this review, we summarize the mode of action of AMPs such as magainin 2 (Mag) and CPPs such as transportan 10 (TP10), revealed by the single GUV methods, and especially we focus on the role of membrane tension in actions of Mag and TP10 and the mechanisms of their actions. First, we explain the characteristics of the single GUV method briefly. Next, we summarize the recent view on the effect of tension on physical properties of lipid bilayers and describe the role of tension in actions of Mag and TP10. Some experimental results indicate that Mag-induced pore is a stretch-activated pore. The effect of packing of transbilayer asymmetric lipid on Mag-induced pore formation is described. On the other hand, entry of fluorescent dye, carboxyfluorescein (CF)-labeled TP10 (i.e., CF-TP10), into single GUVs without pore formation is affected by tension and high concentration of cholesterol. Pre-pore model for translocation of CF-TP10 across lipid bilayer is described. The experimental methods and their analysis described here are useful for investigation of functions of the other types of AMPs, CPPs, and proteins.

Elementary Processes and Mechanisms of Interactions of Antimicrobial Peptides with Membranes-Single Giant Unilamellar Vesicle Studies.

To elucidate the mechanisms of action of antimicrobial peptides (AMPs) and to develop de novo designed peptides with activities similar to those of AMPs, it is essential to elucidate the detailed processes of AMP interactions with plasma membranes of bacterial and fungal cells and model membranes (lipid bilayers). In this mini-review, we summarize the present state of knowledge of the interactions of AMPs with lipid vesicles obtained using the single giant unilamellar vesicle (GUV) method. Currently, three modes of action of AMPs on GUVs have been defined. The elementary processes of interactions of AMPs with lipid vesicles revealed by the single GUV method, and the advantages of this technique, are described and discussed. For example, the single GUV method can be used to determine rate constants of AMP-induced pore formation or local rupture and membrane permeation of internal contents through the pore or the local rupture, the transbilayer movement of lipids, and the relationship between the location of AMPs and pore formation. Effects of membrane tension and of asymmetric lipid packing in the bilayer on AMP-induced pore formation also are described. On the basis of these data, we discuss the present state of understanding of the interaction of AMPs with lipid bilayers and future prospects for AMP studies.

Effect of membrane tension on transbilayer movement of lipids.

The stretching of plasma membranes of cells and lipid bilayers of vesicles affects the physical properties of the membrane as well as the functions of proteins/peptides in the membranes. Here, we examined the effect of membrane tension on the rate constant of the transbilayer movement (kFF) of fluorescent probe-labeled lipids using a new method. Specifically, we recently reported [Hasan et al., Langmuir 34, 3349 (2018)] the development of a technique that employs giant unilamellar vesicles (GUVs) with asymmetric lipid compositions in two monolayers. In the present work, we found that the kFF greatly increased with tension without leakage of water-soluble fluorescent probes from the GUV lumen (i.e., without the formation of pores in the GUV membrane). We discussed the plausible mechanisms for the effect of tension on the transbilayer movement of lipids. As one of the mechanisms, we hypothesized that the transbilayer movement of lipids occurs through the lateral diffusion of lipids in the walls of hydrophilic pre-pores.

Mechanism of Initial Stage of Pore Formation Induced by Antimicrobial Peptide Magainin 2.

Antimicrobial peptide magainin 2 forms pores in lipid bilayers, a property that is considered the main cause of its bactericidal activity. Recent data suggest that tension or stretching of the inner monolayer plays an important role in magainin 2-induced pore formation in lipid bilayers. Here, to elucidate the mechanism of magainin 2-induced pore formation, we investigated the effect on pore formation of asymmetric lipid distribution in two monolayers. First, we developed a method to prepare giant unilamellar vesicles (GUVs) composed of dioleoylphosphatidylglycerol (DOPG), dioleoylphosphatidylcholine (DOPC), and lyso-PC (LPC) in the inner monolayer and of DOPG/DOPC in the outer monolayer. We consider that in these GUVs, the lipid packing in the inner monolayer was larger than that in the outer monolayer. Next, we investigated the interaction of magainin 2 with these GUVs with an asymmetric distribution of LPC using the single GUV method, and found that the rate constant of magainin 2-induced pore formation, kp, decreased with increasing LPC concentration in the inner monolayer. We constructed a quantitative model of magainin 2-induced pore formation, whereby the binding of magainin 2 to the outer monolayer of a GUV induces stretching of the inner monolayer, causing pore formation. A theoretical equation defining kp as a function of magainin 2 surface concentration, X, reasonably explains the experimental relationship between kp and X. This model quantitatively explains the effect on kp of the LPC concentration in the inner monolayer. On the basis of these results, we discuss the mechanism of the initial stage of magainin 2-induced pore formation.

Low-pH-Induced Lamellar to Bicontinuous Primitive Cubic Phase Transition in Dioleoylphosphatidylserine/Monoolein Membranes.

Electrostatic interactions (EIs) play important roles in the structure and stability of inverse bicontinuous cubic (QII) phases of lipid membranes. We examined the effect of pH on the phase of dioleoylphosphatidylserine (DOPS)/monoolein (MO) membranes at low ionic strengths using small-angle X-ray scattering (SAXS). We found that the phase transitions from lamellar liquid-crystalline (Lα) to primitive cubic (QIIP) phases in DOPS/MO (2/8 molar ratio) membranes occurred in buffers containing 50 mM NaCl at and below the final pH of 2.75 as the pH of the membrane suspension was decreased from a neutral value. The kinetic pathway of this transition was revealed using time-resolved SAXS with a stopped-flow apparatus. The first step is a rapid transition from the Lα phase to the hexagonal II (HII) phase, and the second step is a slow transition from the HII phase to the QIIP phase. We determined the rate constants of the first step, k1, and of the second step, k2, by analyzing the time course of SAXS intensities quantitatively. The k1 value increased with temperature. The analysis of this result provided the values of its apparent activation energy, which were constant over temperature but increased with pH. This can be explained by an EI effect on the free energy of the transition state. In contrast, the k2 value decreased with temperature, indicating that the true activation energy increased with temperature. These experimental results were analyzed using the theory of the activation energy of phase transitions of lipid membranes when the free energy of the transition state depends on temperature. On the basis of these results, we discussed the mechanism of this phase transition.

Dietary mushroom (Pleurotus ostreatus) ameliorates atherogenic lipid in hypercholesterolaemic rats.

1. The effects of edible oyster mushroom Pleurotus ostreatus on plasma and liver lipid profiles and on the plasma total anti-oxidant status were estimated in hyper- and normocholesterolaemic Long Evans rats. 2. The feeding of 5% powder of the fruiting bodies of P. ostreatus mushrooms to hypercholesterolaemic rats reduced their plasma total cholesterol by approximately 28%, low-density lipoprotein-cholesterol by approximately 55%, triglyceride by approximately 34%, non-esterified fatty acid by approximately 30% and total liver cholesterol levels by > 34%, with a concurrent increase in plasma high-density lipoprotein-cholesterol concentration of > 21%. However, these effects were not observed in mushroom-fed normocholesterolaemic rats. 3. Mushroom feeding significantly increased plasma fatty acid unsaturation in both normo- and hypercholesterolaemic rats. 4. Plasma total anti-oxidant status, as estimated by the oxidation of 2,2'-azino-bis-[3-ethylbenz-thiazoline-6-sulphonic-acid], was significantly decreased in mushroom-fed hypercholesterolaemic rats, concomitant with a decrease in plasma total cholesterol. 5. The present study suggests that 5% P. ostreatus supplementation provides health benefits, at least partially, by acting on the atherogenic lipid profile in the hypercholesterolaemic condition.