Mechanism and antibacterial synergies of poly(Dabco-BBAC) nanoparticles against multi-drug resistant Pseudomonas aeruginosa isolates from human burns

Multi-drug resistant bacteria are a major problem in the treatment of infectious diseases, such as pneumonia, meningitis, or even coronavirus disease 2019 (COVID-19). Cationic nanopolymers are a new type of antimicrobial agent with high efficiency. We synthesized and characterized cationic polymer based on 1,4-diazabicyclo [2.2.2] octane (DABCO) and Bis (bromoacetyl)cystamine (BBAC), named poly (DABCO-BBAC) nanoparticles(NPs), and produced 150 nm diameter NPs. The antibacterial activity of poly (DABCO-BBAC) against eight multi drug resistant (MDR) Pseudomonas aeruginosa isolates from human burns, its possible synergistic effect with gentamicin, and the mechanism of action were examined. Poly(DABCO-BBAC) could effectively inhibit and kill bacterial strains at a very low concentration calculated by minimum inhibitory concentration (MIC) assay. Nevertheless, its synergism index with gentamicin showed an indifferent effect. Moreover, transmission electron microscopy and lipid peroxidation assays showed that poly (DABCO-BBAC) distorted and damaged the bacterial cell wall. These results suggest that the poly (DABCO-BBAC) could be an effective antibacterial agent for MDR clinical pathogens.

Interval type-2 Fuzzy control and stochastic modeling of COVID-19 spread based on vaccination and social distancing rates

BACKGROUND AND OBJECTIVE

Besides efforts on vaccine discovery, robust and intuitive government policies could also significantly influence the pandemic state. However, such policies require realistic virus spread models, and the major works on COVID-19 to date have been only case-specific and use deterministic models. Additionally, when a disease affects large portions of the population, countries develop extensive infrastructures to contain the condition that should adapt continuously and extend the healthcare system's capabilities. An accurate mathematical model that reasonably addresses these complex treatment/population dynamics and their corresponding environmental uncertainties is necessary for making appropriate and robust strategic decisions.

METHODS

Here, we propose an interval type-2 fuzzy stochastic modeling and control strategy to deal with the realistic uncertainties of pandemics and manage the size of the infected population. For this purpose, we first modify a previously established COVID-19 model with definite parameters to a Stochastic SEIAR (S²EIAR) approach with uncertain parameters and variables. Next, we propose to use normalized inputs, rather than the usual parameter settings in the previous case-specific studies, hence offering a more generalized control structure. Furthermore, we examine the proposed genetic algorithm-optimized fuzzy system in two scenarios. The first scenario aims to keep infected cases below a certain threshold, while the second addresses the changing healthcare capacities. Finally, we examine the proposed controller on stochasticity and disturbance in parameters, population sizes, social distance, and vaccination rate.

RESULTS

The results show the robustness and efficiency of the proposed method in the presence of up to 1% noise and 50% disturbance in tracking the desired size of the infected population. The proposed method is compared to Proportional Derivative (PD), Proportional Integral Derivative (PID), and type-1 fuzzy controllers. In the first scenario, both fuzzy controllers perform more smoothly despite PD and PID controllers reaching a lower mean squared error (MSE). Meanwhile, the proposed controller outperforms PD, PID, and the type-1 fuzzy controller for the MSE and decision policies for the second scenario.

CONCLUSIONS

The proposed approach explains how we should decide on social distancing and vaccination rate policies during pandemics against the prevalent uncertainties in disease detection and reporting.

Molecular characterization of polymorphisms among Pseudomonas aeruginosa strains isolated from burn patients' wounds

Pseudomonas aeruginosa is one of the most common reasons for nosocomial infections. Given the high morbidity and mortality, as well as the cost of management, particularly in developing countries, burn injuries are considered important health concerns. Owing to the increased rate of resistance against antibiotics, this study aimed to isolate Pseudomonas aeruginosa strains from burn patient's wounds by analyzing antibiotic susceptibility and genetic profiling. In this regard, we explored the relationship between the nucleotide sequence and antibiotic susceptibility. In this cross-sectional study, 107 isolates of P. aeruginosa were collected from a major burn center in Tehran, Iran. The isolates were characterized with standard biochemical tests and examined by applying the Disk Diffusion method to find the patterns of sensitivity, and their genetic relationship was revealed by RAPD-PCR method. According to the antibiogram results, most of the isolates were resistant to 3 or more antibiotics tested and the most sensitivity was related to the Colistin antibiotic. RAPD-PCR method revealed a high polymorphism among P. aeruginosa isolates in Tehran. There was no significant association between the genotype groups and antibiotic susceptibility profiles. We evaluated the pattern of resistance to pathogenic organisms and identified multi-drug resistant organisms. Currently, Colistin antibiotic is the most suitable treatment option for burned patients. RAPD-PCR is a genotyping method with high efficiency for typing and categorizing different isolates of MDR-P. aeruginosa.

Factors associated with breast self-examination among Malaysian women teachers

The purpose of this study was to examine factors related to breast self-examination (BSE) among teachers in Selangor, Malaysia. A cross-sectional study was conducted among 425 female teachers in 20 randomly selected secondary schools. A self-administered questionnaire based on the health belief model was randomly selected secondary schools. A self-administered questionnaire based on the health belief model was used, including sociodemographic background and knowledge, beliefs and practices about breast cancer and BSE. Only 19% of the women performed BSE on a regular basis. Higher knowledge about breast cancer, greater confidence in performing BSE and regular visits to a physician were significant predictors for practising BSE. To promote BSE practice among Malaysian women, tailored health education and health promotion programmes should be developed based on a specific understanding of women's health beliefs.

Reliability and validity of Champion's Health Belief Model Scale for breast cancer screening among Malaysian women

INTRODUCTION

Breast cancer is the leading cause of cancer deaths in Malaysian women, and the use of breast self-examination (BSE), clinical breast examination (CBE) and mammography remain low in Malaysia. Therefore, there is a need to develop a valid and reliable tool to measure the beliefs that influence breast cancer screening practices. The Champion's Health Belief Model Scale (CHBMS) is a valid and reliable tool to measure beliefs about breast cancer and screening methods in the Western culture. The purpose of this study was to translate the use of CHBMS into the Malaysian context and validate the scale among Malaysian women.

METHODS

A random sample of 425 women teachers was taken from 24 secondary schools in Selangor state, Malaysia. The CHBMS was translated into the Malay language, validated by an expert's panel, back translated, and pretested. Analyses included descriptive statistics of all the study variables, reliability estimates, and construct validity using factor analysis.

RESULTS

The mean age of the respondents was 37.2 (standard deviation 7.1) years. Factor analysis yielded ten factors for BSE with eigenvalue greater than 1 (four factors more than the original): confidence 1 (ability to differentiate normal and abnormal changes in the breasts), barriers to BSE, susceptibility for breast cancer, benefits of BSE, health motivation 1 (general health), seriousness 1 (fear of breast cancer), confidence 2 (ability to detect size of lumps), seriousness 2 (fear of long-term effects of breast cancer), health motivation 2 (preventive health practice), and confidence 3 (ability to perform BSE correctly). For CBE and mammography scales, seven factors each were identified. Factors for CBE scale include susceptibility, health motivation 1, benefits of CBE, seriousness 1, barriers of CBE, seriousness 2 and health motivation 2. For mammography the scale includes benefits of mammography, susceptibility, health motivation 1, seriousness 1, barriers to mammography seriousness 2 and health motivation 2. Cronbach's alpha reliability coefficients ranged from 0.774 to 0.939 for the subscales.

CONCLUSION

The translated version of the CHBMS was found to be a valid and reliable tool for use with Malaysian women. It can be used easily to evaluate the health beliefs about breast cancer, BSE, CBE and mammography and for planning interventions. For greater applicability, it is recommended that this tool be tested among ethnically diverse populations.

Effect of filter vent blocking on carbon monoxide exposure from selected lower tar cigarette brands

Two studies were conducted to determine the effect of blocking filter vents on carbon monoxide (CO) exposure under ad lib smoking conditions. In Study 1, 12 daily cigarette smokers smoked cigarettes from the brands Now (1 mg tar by the FTC Method) and Marlboro Lights (10 mg tar) under each of two vent-blocking conditions (unblocked and finger blocked). Blocking filter vents with fingers led to an 85% increase in CO for the brand Now, but had no added effect on CO exposure from the Marlboro Lights. In Study 2, another 12 daily cigarette smokers smoked cigarettes from each of four additional brands: Carlton (1 mg tar), Now (2 mg tar), Virginia Slims Ultra-lights (5 mg tar), and Virginia Slims Lights (8 mg tar). Blocking filter vents with the lips caused all four brands to produce equal CO exposures. Blocking vents increased smokers' exposure to CO by 239% when smoking Carltons and by 44% when smoking Nows. No significant increases in CO with blocking were found for either of the Virginia Slims brands. These results suggest that the degree to which a brand is ventilated determines whether that brand is susceptible to increased CO yields as a result of vent blocking.

Optical properties of rat liver between 350 and 2200 nm

Previous investigators have determined the optical properties of the liver at isolated wavelengths using various models of light propagation. In this study we derived coefficients for absorption, scattering, and anisotropy for rat liver between 350 and 2200 nm using measurements of integrated reflectance, transmittance, and on-axis attenuation and a diffusion approximation algorithm to solve the 1-D transport equation. These results were used to estimate the effective attenuation coefficient, penetration depth, and temperature rise induced by laser irradiation. The data should be of value to investigators in the field of tissue optics and developers of photomedical applications involving the liver.