Murein lipoprotein is a critical outer membrane component involved in Salmonella enterica serovar typhimurium systemic infection

Lipopolysaccharide (LPS) and Braun (murein) lipoprotein (Lpp) are major components of the outer membrane of gram-negative enteric bacteria that function as potent stimulators of inflammatory and immune responses. In a previous paper, we provided evidence that two functional copies of the lipoprotein gene (lppA and lppB) located on the chromosome of Salmonella enterica serovar Typhimurium contributed to bacterial virulence. In this study, we characterized lppA and lppB single-knockout (SKO) mutants and compared them with an lpp double-knockout (DKO) mutant using in vitro and in vivo models. Compared to the lpp DKO mutant, which was nonmotile, the motility of the lpp SKO mutants was significantly increased (73 to 77%), although the level of motility did not reach the level of wild-type (WT) S. enterica serovar Typhimurium. Likewise, the cytotoxicity was also significantly increased when T84 human intestinal epithelial cells and RAW264.7 murine macrophages were infected with the lpp SKO mutants compared to the cytotoxicity when cells were infected with the lpp DKO mutant. The level of interleukin-8 (IL-8) in polarized T84 cells infected with the lppB SKO mutant was significantly higher (two- to threefold higher), reaching the level in cells infected with WT S. enterica serovar Typhimurium, than the level in host cells infected with the lppA SKO mutant. The lpp DKO mutant induced minimal levels of IL-8. Similarly, sera from mice infected with the lppB SKO mutant contained 4.5- to 10-fold-higher levels of tumor necrosis factor-alpha and IL-6; the levels of these cytokines were 1.7- to 3.0-fold greater in the lppA SKO mutant-infected mice than in animals challenged with the lpp DKO mutant. The increased cytokine levels observed with the lppB SKO mutant in mice correlated with greater tissue damage in the livers and spleens of these mice than in the organs of animals infected with the lppA SKO and lpp DKO mutants. Moreover, the lppB SKO mutant-infected mice had increased susceptibility to death. Since the lpp DKO mutant retained intact LPS, we constructed an S. enterica serovar Typhimurium triple-knockout (TKO) mutant in which the lppA and lppB genes were deleted from an existing msbB mutant (msbB encodes an enzyme required for the acylation of lipid A). Compared to the lpp DKO and msbB SKO mutants, the lpp-msbB TKO mutant was unable to induce cytotoxicity and to produce cytokines and chemokines in vitro and in vivo. These studies provided the first evidence of the relative contributions of Lpp and lipid A acylation to Salmonella pathogenesis.     

Solid-state dye-sensitized solar cells based on Zn1−xSnxO nanocomposite photoanodes

Solid-state dye-sensitized solar cells (ss-DSSCs) comprising Sn²⁺-substituted ZnO nanopowder were purposefully tailored via a co-precipitation method. The solar cells assembled in this work were sensitized with N719 ruthenium dye and insinuated with spiro-OMeTAD as a solid hole transport layer (HTL). Evidently, significant enhancement in cell efficiency was accomplished with Sn²⁺ ions-substituted ZnO photoelectrodes by maintaining the weight ratio of SnO at 5%. The overall power conversion efficiency was improved from 3.0% for the cell with pure ZnO to 4.3% for the cell with 5% SnO substitution. The improvement in the cell efficiency with Sn²⁺-substituted ZnO photoelectrodes is attributed to the considerably large surface area of the nanopowders for dye adsorption, efficient charge separation and the suppression of charge recombination provided by SnO. Furthermore, the energy distinction between the conduction band edges of SnO and ZnO implied a type II band alignment. Moreover, the durability as well as the stability of 15 assembled cells were studied to show the outstanding long-term stability of the devices made of Sn²⁺ ion substituted ZnO, and the PCE of each cell remained stable and ∼96% of its primary value was retained for up to 100 h. Subsequently, the efficacy was drastically reduced to ∼35% after 250 h of storage.

Solid-state dye-sensitized solar cells (ss-DSSCs) comprising Sn²⁺-substituted ZnO nanopowder were purposefully tailored via a co-precipitation method.     

Evaluation of knowledge and behavior of workers in Prince Mohammed International Airport in Western Saudi Arabia regarding public health emergency measures applied during Hajj season 2014

Objectives:

To evaluate the knowledge and behavior of workers at a Saudi airport regarding public health emergency measures applied during Hajj season.

Methods:

This study is a cross-sectional study conducted at the Prince Mohammed International Airport in Al-Madinah Al-Munawwarah, Saudi Arabia between August and September 2014. Data were collected by semi-structured questionnaires during personal interviews. Non-random purposive sampling was conducted to target workers at higher risk of acquiring infection from travellers.

Results:

One hundred and eighty-six participants were recruited of whom 92.5% were males. The study participants were workers in 8 different sectors. Twenty-six percent of the participants were health workers. Non-health workers were more likely to be concerned on acquiring infection while working at the airport compared with health workers (p=0.023). The most commonly feared disease was Ebola viral disease (EBV) among 30% of health workers, and 47% of non-health workers. Approximately 47% of non-health workers reported no knowledge of the procedures implemented during public health emergencies. The proportion of participants who received public health related training among non-health workers was significantly lower compared with health workers (p<0.00001).

Conclusion:

More emphasis should be given to educating airport workers on the potential health threats at the airport. Specific guidelines for public health emergencies at the airport should be established and communicated with airport sectors.Airports are frontier gates where proper public health measures are likely to reduce the possibility of allowing the entrance of communicable disease to a country. According to the World Health Organization (WHO) International Health Regulations mandate WHO member states to ensure that every designated point of entry is equipped with staff and instruments enabling smooth movements of the travellers while maintaining appropriate public health measures.1 Maintaining such regulations is likely to enhance proper travellers’ movement during public health emergencies by reducing possible interference between application of preventive public health measures, and the ability of travellers to access the designated points of entry. Additionally, ensuring the application of public health measures might aid in preventing the occurrence of any public health emergencies. A public health emergency is defined as any situation with health consequences that are likely to overwhelm the community’s routine capability of addressing them. A health situation can be considered as an emergency if there is a risk due to timing, such as facing emerging diseases threats during Hajj season, scale, as with an overwhelming number of causalities, or due to the unpredictability of the situation. Defining the nature of potential public health emergencies is crucial to allow competent development of preparedness plans.2 Having a large number of passengers arriving at a particular point of entry during a limited time is a burden on the available health services. A meticulous state of readiness is required to respond to any risk of spreading a communicable disease. The state of readiness is maintained by several steps including preparation of staff, equipment, and buildings.3,4 The burden of not maintaining effective public health event response measures is aggravated if an epidemic is announced in a particular region of the globe where travellers form these areas are scheduled to arrive in the country. During the Hajj season of 2014, the Ebola Virus Disease (EVD), which is a viral hemorrhagic disease, was announced as an epidemic disease in Guinea, Liberia, and Sierra Leone in West Africa. Additionally, a localized spread of the virus was announced in certain areas of Nigeria.5 The Saudi Arabian government, as a preventive measure, decided to prevent citizens of EVD-affected countries from entering the country. However, nationals of Nigeria were exempt as no extended transmission of EVD was announced.6,7 Nonetheless, several procedures were applied to prevent the transmission of Ebola virus among thousands of Nigerian pilgrims arriving in the country. These measures were mainly related to exit screening of travellers in Nigeria,8 and entry screening at points of entry in Saudi Arabia. Additionally, the Ministry of Health in Saudi Arabia produced response plans for infectious diseases (Middle East Respiratory Syndrome [MERS] and EVD) to be implemented during Hajj.9 There are many potential sources of infectious disease transmission from a single infected individual. The presence of infected travellers, such as an EVD infection, on an aircraft increases the risk of transmitting infection to neighboring passengers and flight crew. Airport workers, such as ground workers handling cleaning of aircrafts and lavatories, are at risk of the infection, especially with the presence of spilled infectious materials. Airport workers handling the flow of passengers during busy times are at risk of acquiring infection such as immigration, customs, security, and healthcare workers. Therefore, all of these individuals have to be aware of the potential health threats at the airport, should be aware of preventive methods, how to use preventive methods, and know what to do when facing a public health emergency event in the airport. Prince Mohammed Airport (Al-Madinah, Saudi Arabia) workers’ level of knowledge of the potential health threat at the airport is currently not known. Additionally, the attitude and practice of the staff when a public health emergency is announced in the airport is not measured. The significance of this study stems from the ability to investigate the degree to which airport workers, at the time of dealing with travellers during Hajj season, were able to deal with potential urgent infectious cases, and to adhere to the relevant protective guidelines.     

Effects of pre-emptive analgesia on efficacy of buccal infiltration during pulpotomy of mandibular primary molars: a double-blinded randomized controlled trial

Objective: To assess the effect of preoperative administration of ibuprofen and acetaminophen on the efficacy of buccal infiltration for pulp therapy in mandibular primary molars.

Materials and methods: A randomized controlled trial with an ID no. NCT03423329 in Clinical-Trials.gov was conducted in the outpatient clinic of Paediatric Dentistry Department at Ain Shams University. The study was designed with two test arms where either ibuprofen or acetaminophen was administered to children whereas in the control arm a multivitamin placebo was used. Children's self-reported pain responses were recorded using Wong–Baker FACES pain scale. For statistical analysis, Chi-square test or Fisher’s exact test was used to compare between the three groups whereas Friedman’s test was used to study changes within each group.

Results: In a sample of 60 children, a significant decrease in the mean pain rating scores was detected in all groups where success rates ranged from 40% with ibuprofen to 55% and 65% with acetaminophen and placebo, respectively. However, there was no statistically significant difference between the three groups regarding severity of pain during access cavity preparation.

Conclusions: Both analgesics have no clinical advantage over the placebo in increasing the efficacy of buccal infiltration during pulp therapy in mandibular primary molars.