Tyrosine-derived polymeric surfactant nanospheres insert cholesterol in cell membranes.

HYPOTHESIS: The design of biodegradable tyrosine-derived polymeric surfactants (TyPS) through the use of calculated thermodynamic parameters could lead to phospholipid membrane surface modifiers capable of controlling cellular properties such as viability. Delivery of cholesterol by TyPS nanospheres into membrane phospholipid domains could provide further controlled modulation of membrane physical and biological properties. EXPERIMENT: Calculated Hansen solubility parameters (∂T) and hydrophile:lipophile balances (HLB) were applied to design and synthesize a small family of diblock and triblock TyPS with different hydrophobic blocks and PEG hydrophilic blocks. Self-assembled TyPS/cholesterol nanospheres were prepared in aqueous media via co-precipitation. Cholesterol loading and Langmuir film balance surface pressures of phospholipid monolayers were obtained. TyPS and TyPS/cholesterol nanosphere effects on human dermal cell viability were evaluated by cell culture using poly(ethylene glycol) (PEG) and Poloxamer 188 as controls. FINDINGS: Stable TyPS nanospheres incorporated between 1% and 5% cholesterol. Triblock TyPS formed nanosphere with dimensions significantly smaller than diblock TyPS nanospheres. In accord calculated thermodynamic parameters, cholesterol binding increased with increasing TyPS hydrophobicity. TyPS inserted into phospholipid monolayer films in a manner consistent with their thermodynamic properties and TyPS/cholesterol nanospheres delivered cholesterol into the films. Triblock TyPS/cholesterol nanospheres increased human dermal cell viability, which was indicative of potentially beneficial TyPS effects on cell membrane surface properties.

A peculiar cell cycle arrest at g2/m stage during the stationary phase of growth in the wine yeast Hanseniaspora vineae.

Yeasts of the genus Hanseniaspora gained notoriety in the last years due to their contribution to wine quality, and their loss of several genes, mainly related to DNA repair and cell cycle processes. Based on genomic data from many members of this genus, they have been classified in two well defined clades: the "faster-evolving linage" (FEL) and the "slower-evolving lineage" (SEL). In this context, we had detected that H. vineae exhibited a rapid loss of cell viability in some conditions during the stationary phase compared to H. uvarum and S. cerevisiae. The present work aimed to evaluate the viability and cell cycle progression of representatives of Hanseniaspora species along their growth in an aerobic and discontinuous system. Cell growth, viability and DNA content were determined by turbidity, Trypan Blue staining, and flow cytometry, respectively. Results showed that H. uvarum and H. opuntiae (representing FEL group), and H. osmophila (SEL group) exhibited a typical G1/G0 (1C DNA) arrest during the stationary phase, as S. cerevisiae. Conversely, the three strains studied here of H. vineae (SEL group) arrested at G2/M stages of cell cycle (2C DNA), and lost viability rapidly when enter the stationary phase. These results showed that H. vineae have a unique cell cycle behavior that will contribute as a new eukaryotic model for future studies of genetic determinants of yeast cell cycle control and progression.

Influence of Marine Yeast Debaryomyces hansenii on Antifungal and Physicochemical Properties of Chitosan-Based Films.

Chitosan-based film with and without antagonistic yeast was prepared and its effect against Penicillium italicum was evaluated. The biocompatibility of yeast cells in the developed films was assessed in terms of population dynamics. Furthermore, the impact on physicochemical properties of the prepared films with and without yeast cells incorporated were evaluated in terms of thickness, mechanical properties, color and opacity. Chitosan films with the antagonistic yeast entrapped exhibited strong antifungal activity by inhibiting the mycelial development (55%), germination (45%) and reducing the sporulation process (87%). Chitosan matrix at 0.5% and 1.0% was maintained over 9 days of cell viability. However, at 1.5% of chitosan the population dynamics was strongly affected. The addition of yeast cells only impacted color values such as a*, b*, chroma and hue angle when 1.0% of chitosan concentration was used. Conversely, luminosity was not affected in the presence of yeast cells as well as the opacity. Besides, the addition of antagonistic yeast improved the mechanical resistance of the films. The addition of D. hansenii in chitosan films improve their efficacy for controlling P. italicum, and besides showed desirable characteristics for future use as packaging for citrus products.

A Sensitive and Quantitative Assay to Enumerate and Measure Mycobacterium leprae Viability in Clinical and Experimental Specimens.

Mycobacterium leprae, the etiologic agent of leprosy, cannot be cultured on artificial media. This characteristic, coupled with its long generation time, presents a number of unique challenges to studying this pathogen. One of the difficulties facing both researchers and clinicians is the absence of a rapid test to measure the viability of M. leprae in clinical or experimental specimens. The lack of such a tool limits the understanding of M. leprae immunopathogenesis and makes determining the efficacy of drug treatments difficult. With this in mind, we developed a robust two-step molecular viability assay (MVA) that first enumerates the M. leprae in the tissue; then, this data is used to normalize bacterial RNA quantities for the second step, in which the expression of M. leprae esxA and hsp18 are measured. This assay is specific and sensitive enough to be used on most clinical samples. This protocol describes the steps required to extract DNA and RNA from M. leprae-infected tissue, enumerate M. leprae, and measure M. leprae viability based on the normalized expression of two M. leprae-specific genes (hsp18 and esxA). This protocol also outlines an optimal laboratory design and workflow for performing this assay. © 2022 The Leprosy Mission Nepal. Current Protocols published by Wiley Periodicals LLC. This article has been contributed to by US Government employees and their work is in the public domain in the USA. Basic Protocol 1: DNA and RNA P purification from M. leprae-infected tissue Basic Protocol 2: Enumeration of M. leprae by RLEP qPCR on the DNA fraction Basic Protocol 3: Calculation of M. leprae per tissue and normalization of RNA Basic Protocol 4: Reverse-transcription of normalized RNA to generate cDNA Basic Protocol 5: Determination of M. leprae viability using HSP18 and ESXA qPCR on the cDNA Support Protocol 1: M. leprae qPCR primer/probe stock preparation Support Protocol 2: Preparation of plasmid stocks and standard curves.

Padronização do uso da monoazida de propídio (PMAxxTM) na detecção de viabilidade do Mycobacterium leprae / Standardization of the use of propidium monoazide (PMAxxTM) in the detection of Mycobacterium leprae viability

Introdução A hanseníase é uma doença infecciosa crônica, causada peloMycobacterium leprae, que se manifesta na pele e pode invadir o sistema nervoso periférico do paciente. O cultivo de seu agente etiológico em meios de cultura artificiaisou celulares ainda é um desafio e obstáculo para estudos relacionados à sua microbiologia. Para avaliar a viabilidade de células bacterianas, utiliza-se corantes fluorescente, como a monoazida de propídeo (PMA). O corante penetra somente nas células que estão com a membrana celular comprometida e reage com fração de hidrocarboneto a fim de resultar em uma modificação permanente do DNA. Objetivo Padronizar a utilização do corante monoazida de propídeo (PMAxx™) em combinação com a técnica de reação em cadeia da polimerase em tempo real (RT qPCR) para detecção da viabilidade do M. leprae. Metodologia Diferentes concentrações de PMAxx™ foram adicionadas a 250µl de suspensão bacilar purificada, proveniente de coxim plantar de camundongos previamente infectados. As amostras foram incubadas no escuro por diferentes tempos. Após a incubação, foram fotoativadas por exposição em lâmpada halógena de 650 W. Foram avaliados os parâmetros de concentração bacilar, tempo de incubação no escuro, tempo de exposição à luz e concentração do PMAxx™. O DNA do bacilo foi extraído utilizando-se um kit comercial e amplificadas por RT qPCR, com uso de primers específicos para as regiões Specific Repetitive Element (RLEP) do DNA de M. leprae Resultados Não houve diferença significativa no valor do ΔCt em nenhuma das concentrações de bacilos, indicando que não foi possível fazer a discriminação entre células vivas e inviáveis. O tempo ideal de incubação no escuro foi de 60 minutos, pois apresentaram uma diferenciação significativa do ΔCtvivo-morto com PMAxxTM e ΔCtmorto com e sem PMAxxTM. Em relação ao tempo de fotoativação, o maior valor de ΔCt observado foi submetido a sete minutos em exposição à luz. A concentração do PMAxxTM que apresentou uma diferenciação de ΔCt maior foi de 25µL. Discussão Os resultados mostram que o PMAxx™ tem uma boa eficácia com outras bactérias, mas ainda apresenta dificuldades em intercalar ao DNA de M. leprae. O uso do corante após análise com RT qPCR/RLEP para o bacilo é um método que ainda necessita de ajustes nos parâmetros como purificação da amostra, tempo de exposição e fotoativação. Esses dados ainda são preliminares e não inviabilizam a perspectiva de novos experimentos a partir dos ajustes nos parâmetros já avaliados.

Introduction Leprosy is a chronic infectious disease, caused by Mycobacterium leprae, which manifests itself in the skin and may invade the peripheral nervous system of the patient. Culturing its etiologic agent in artificial or cell culture media is still a challenge and obstacle for studies related to its microbiology. To assess the viability of bacterial cells, fluorescent dyes such as propidium monoazide (PMA) are used. The dye penetrates only cells with a compromised cell membrane and reacts with a hydrocarbon fraction to result in a permanent modification of the DNA Objective To standardize the use of the dye propidium monoazide (PMAxx™) in combination with the real-time polymerase chain reaction (RT qPCR) technique for detection of M. leprae viability Methodology Different concentrations of PMAxx™ were added to 250µl of purified bacillary suspension from plantar cushion of previously infected mice. The samples were incubated in the dark for different times. After incubation, they were photoactivated by exposure in a 650 W halogen lamp. The parameters of bacillary concentration, incubation time in the dark, light exposure time and concentration of PMAxx™ were evaluated. The bacillus DNA was extracted using a commercial kit and amplified by RT qPCR using specific primers for the Specific Repetitive Element (RLEP) regions of the M. leprae Results There was no significant difference in the ΔCt value at any of the bacilli concentrations, indicating that discrimination between live and non-viable cells was not possible. The optimal incubation time in the dark was 60 minutes, as they showed a significant differentiation of ΔClive-dead with PMAxxTM and ΔCtdead with and without PMAxxTM. Regarding photoactivation time, the highest value of ΔCt observed was subjected to seven minutes in light exposure. The concentration of PMAxxTM that showed a greater differentiation of ΔCt was 25µL Discussion The results show that PMAxx™ has good efficacy with other bacteria, but still presents difficulties in intercalating to M. leprae DNA. The use of the dye after analysis with RT qPCR/RLEP for the bacillus is a method that still needs adjustments in parameters such as sample purification, exposure time and photoactivation. These data are still preliminary and do not preclude the prospect of new experiments based on adjustments in the parameters already evaluated.

Heterogeneous persistence of Mycobacterium leprae in oral and nasal mucosa of multibacillary patients during multidrug therapy

BACKGROUND Leprosy is curable by multidrug therapy (MDT) treatment regimen ranging from six to 12 months. The variable levels of tolerance and adherence among patients can, however, result in treatment failure and the emergence of drug-resistant strains. OBJECTIVES Describe the impact of MDT over Mycobacterium leprae viability in patient's oral and nasal mucosa along treatment. METHODS Mycobacterium leprae viability was monitored by quantitative polymerase chain reaction (qPCR) quantification of 16S rRNA in lateral and contralateral scrapings of oral and nasal mucosa of 10 multibacillary patients along the initial five months of treatment. FINDINGS The results demonstrated high heterogenicity of M. leprae viability among patients and between nasal and oral samples. Of six patients who presented good adherence and tolerance to the treatment, only four displayed absence of M. leprae viability in both samples three months after the first MDT dose, while for the other two, the absence of M. leprae viability in the oral and nasal cavities was only detected five months after the first dose. MAIN CONCLUSIONS We concluded that qPCR of 16S rRNA for the determination of M. leprae viability in nasal and oral scraping samples could represent an interesting approach to monitor treatment efficacy.

A genuine mycobacterial thermophile: Mycobacterium hassiacum growth, survival and GpgS stability at near-pasteurization temperatures.

Mycobacterium hassiacum is so far the most thermophilic among mycobacteria as it grows optimally at 50 °C and up to 65 °C in a glycerol-based medium, as verified in this study. Since this and other nontuberculous mycobacteria (NTM) thrive in diverse natural and artificial environments, from where they may access and infect humans, we deemed essential to probe M. hassiacum resistance to heat, a strategy routinely used to control microbial growth in water-supply systems, as well as in the food and drink industries. In addition to possibly being a threat in its own right in rare occasions, M. hassiacum is also a good surrogate for studying other NTM species more often associated with opportunistic infection, namely Mycobacterium avium and Mycobacterium abscessus as well as their strictly pathogenic counterparts Mycobacterium tuberculosis and Mycobacterium leprae. In this regard, this thermophilic species is likely to be useful as a source of stable proteins that may provide more detailed structures of potential drug targets. Here, we investigate M. hassiacum growth at near-pasteurization temperatures and at different pHs and also characterize its thermostable glucosyl-3-phosphoglycerate synthase (GpgS), an enzyme considered essential for M. tuberculosis growth and associated with both nitrogen starvation and thermal stress in different NTM species.

Development of a combined RLEP/16S rRNA (RT) qPCR assay for the detection of viable M. leprae from nasal swab samples.

BACKGROUND: Leprosy continues to be a health problem in endemic areas. More than 200,000 new cases of leprosy per year suggest that transmission of the disease is still ongoing, presumably as airborne infection through nasal droplets. Late diagnosis supports continued transmission and increases the individual risk for functional disabilities. Laboratory tools are considered beneficial to facilitate early detection and clinical assessment of cases. The aim of this study was to validate molecular tools allowing detection, quantification and assessment of viability of M. leprae from nasal swab samples which are easy to obtain without the need of any invasive procedures. METHODS: Validation of two real-time PCRs detecting M. leprae DNA (RLEP qPCR) and RNA (16S rRNA RT qPCR) was conducted on "must not detect"/"must detect" samples and 160 pre-treatment nasal swab samples from 20 clinically diagnosed multibacillary (MB) leprosy patients from Togo. RESULTS: Both assays were 100% M. leprae specific and showed analytical sensitivities of three templates each. Out of 20 clinically diagnosed MB leprosy patients, 15 (75.0%) had a positive RLEP qPCR result from nasal swab samples. The 16S rRNA RT qPCR detected viable bacilli in nasal swab samples of ten out of these 15 RLEP positive patients (66.7%). CONCLUSION: The combined RLEP/16S rRNA (RT) qPCR assay provides a sensitive and specific tool to determine the bacterial load and viability of M. leprae from nasal swab samples and is applicable for early diagnosis, monitoring treatment response and investigating the role of nasal carriage of M. leprae in human-to-human transmission through aerosol infection.

Hansen solubility parameters (HSP) for prescreening formulation of solid lipid nanoparticles (SLN): in vitro testing of curcumin-loaded SLN in MCF-7 and BT-474 cell lines.

Curcumin, a phenolic compound from turmeric rhizome (Curcuma longa), has many interesting pharmacological effects, but shows very low aqueous solubility. Consequently, several drug delivery systems based on polymeric and lipid raw materials have been proposed to increase its bioavailability. Solid lipid nanoparticles (SLN), consisting of solid lipid matrix and a surfactant layer can load poorly water-soluble drugs, such as curcumin, deliver them at defined rates and enhance their intracellular uptake. In the present work, we demonstrate that, despite the drug's affinity to lipids frequently used in SLN production, the curcumin amount loaded in most SLN formulations may be too low to exhibit anticancer properties. The predictive curcumin solubility in solid lipids has been thoroughly analyzed by Hansen solubility parameters, in parallel with the lipid-screening solubility tests for a range of selected lipids. We identified the most suitable lipid materials for curcumin-loaded SLN, producing physicochemically stable particles with high encapsulation efficiency (>90%). Loading capacity of curcumin in SLN allowed preventing the cellular damage caused by cationic SLN on MCF-7 and BT-474 cells but was not sufficient to exhibit drug's anticancer properties. But curcumin-loaded SLN exhibited antioxidant properties, substantiating the conclusions that curcumin's effect in cancer cells is highly dose dependent.

Comparação da atividade de ácidos graxos essenciais e biomembrana na microbiota de feridas crônicas infectadas / Comparison of the activity of fatty essential acids and biomembrane in the microbiota of infected chronic wounds

Em pessoas curadas de hanseníase, as úlceras em membros inferiores representam um desafio aos profissionais, por serem crônicas, infectadas e recorrentes. Esta pesquisa teve como objetivo comparar a ação de uma biomembrana de látex (Biocure®) e de um produto à base de AGE (Dersani®) na microbiota de feridas crônicas infectadas, em pessoas que receberam alta do tratamento para hanseníase. Trata-se de pesquisa realizada no Hospital de Dermatologia Sanitária, de Goiânia (GO), no período de fevereiro a outubro de 2007, na qual participaram 8 pessoas curadas de hanseníase, com 19 feridas infectadas, que foram, alocadas aleatoriamente em grupo A (tratado com Dersani®) e grupo B (tratado com Biocure®). Foram identificados Staphylococcus aureus (50%), Pseudomonas aeruginosa (35,7%), Proteus vulgaris (8,2%), Enterobacter aerogenes (3,3%) e Escherichia coli (2,7%). Os resultados obtidos in vivo sugerem que o Dersani® tenha efeito antimicrobiano positivo sobre Enterobacter aerogenes e o Biocure® sobre Pseudomonas aeruginosa. Os resultados in vitro mostraram ausência de atividade de ambos os produtos sobre os microrganismos isolados das lesões.

For patients cured of leprosy, low-limb ulcers represent a challenge to healthcare workers, for being chronic, infected, and recurrent. This study aimed to compare the latex biomembrane (Biocure TM) and an EFA-based product (Dersani TM) action on the microbiota of infected chronic wounds, in patients discharged from the treatment of leprosy. This is a research carried out at Hospital de Dermatologia Sanitária, in Goiânia-GO, from February to October 2007, in which 8 individuals cured of leprosy, having 19 infected wounds, were randomly allocated in group A (Dersani TM) and group B (Biocure TM). Staphylococcus aureus (50%), Pseudomonas aeruginosa (35.7%), Proteus vulgaris (8.2%), Enterobacter aerogenes (3.3%), and Escherichia coli (2.7%) were isolated. The results obtained in vivo suggest that Dersani TM has a positive antimicrobial effect against Enterobacter aerogenes and Biocure TM against Pseudomonas aeruginosa, despite the in vitro results having shown absence of antimicrobial activity for both products against microorganisms standard and isolated from the wounds.