Antimicrobial tear lipids in the ocular surface defense

The concept of antimicrobial lipids as effectors of innate host defense is an emerging field. There is limited knowledge on the antimicrobial role of lipids in the ocular environment. Tears act as first line of defense to protect the ocular surface from infections. Antimicrobial effects of tear lipids have been demonstrated using meibomian lipids that are the source of majority of lipids in tears. This article describes the knowledge available on the antimicrobial role of tear lipids at the ocular surface and the antimicrobial potential of various lipid classes present in tears that can contribute to antimicrobial protection of the eye. Like other mucosal secretions, tears contain many proteins and lipids with known antimicrobial effects. The antimicrobial defense of tears is far stronger than can be demonstrated by the effects of individual compounds many of which are present in low concentrations but synergistic and additive interactions between them provide substantial antimicrobial protection to the ocular surface. It is inferred that antimicrobial lipids play important role in innate defense of tears, and cooperative interactions between various antimicrobial lipids and proteins in tears provide a potent host defense mechanism that is effective against a broad spectrum of pathogens and renders self-sterilizing properties to tears for keeping the microbial load low at the ocular surface

A Strong Proxy Signature Scheme based on Partial Delegation

Proxy signature scheme is an extension of digital signature scheme first introduced by Mambo et al. in 1996, which allows a signer to delegate the signing capability to a designated person, called a proxy signer. There are three types of delegation, namely, full delegation, partial delegation, and delegation by warrant. In early proxy signature schemes, the identity of the proxy signer can be revealed by any trusted authority if needed. How- ever, a secured proxy signature scheme must satisfy various properties, such as, verifiability, strong un-forgeability, nonrepudiation, privacy, and strong identifiability. In this thesis, we propose a strong proxy signature scheme based on two computationally hard assumptions, namely, Discrete Logarithmic Problem (DLP) and Computational Die-Helmann (CDH) problem, which satisfies all the security properties of a standard proxy signature scheme. The property `strong' refers to the fact that only a designated person can only verify the authenticity of the proxy signature

Exploring antimicrobial properties of cholesterol esters : a systematic literature review

Antibiotic resistance has become an increasingly common problem in treating infectious diseases caused by pathogenic micro-organisms, and this threat is heightened due to the lack of new antibiotic discoveries since the 1980s. This paper aims to summarise the currently available knowledge on the antimicrobial properties of cholesterol esters and to evaluate the use of cholesterol esters as an alternative to antibiotics. A systematic literature search was conducted in three databases namely Pubmed, Embase, and Web of Science to retrieve articles published between 2000 and 2020 where cholesterol esters were the primary or one of the primary examined molecules as part of research targeting immunity and antimicrobial operations. The findings showed antibacterial properties of cholesterol esters, their synergistic activity with antibiotics, antimicrobial role of cholesterol esters in upper respiratory tract and its diseases in humans, and correlation of cholesterol esters with infection protection in physically active individuals. Overall, there is strong evidence that cholesterol esters have antimicrobial properties. However, the currently pooled information available for cholesterol esters' antimicrobial properties is not expansive enough to draw a conclusion on its ability to replace existing antibiotics as a treatment for infections and this warrants future investigation

Antibacterial properties of eucalyptus globulus essential oil against MRSA : a systematic review

Antimicrobial resistance is a huge threat against the public health sphere and is a major cause of global mortality and morbidity. Antibiotic misuse and overuse have led to the development of many resistant bacterial strains. One particular bacterium of concern is methicillin-resistant Staphylococcus aureus (MRSA), which is the most common resistant bacteria in humans. Antibiotic development has been unable to keep up with the rapid evolution of antibiotic-resistant organisms, and there is an urgent need to identify alternative agents to combat this problem. The purpose of this systematic review is to explore the literature on the antibacterial properties of Eucalyptus globulus essential oil against MRSA. The articles used in this review were obtained through a systematic search of the literature across four databases, with the timeline being between 2002 and 2022. Twenty studies were included in this review, which used various methods to investigate the antibacterial properties of E. globulus essential oil, alone or in combination with other agents, against MRSA. The findings suggest that E. globulus essential oil has antibacterial properties against MRSA, which can be enhanced when used in combination with other agents, such as other essential oils and antibiotics

Meibum lipid hydrocarbon chain branching and rheology after hematopoietic stem cell transplantation

Purpose: Meibum from donors who have had hematological stem cell transplantations (MHSCT) are susceptible to severe dry eye symptoms and exhibit very high lipid order (stiffness) compared with meibum from donors without dry eye (Mn). Since lipid order could have functional consequences, we compared the rheology and composition of Mn and MHSCT to measure meibum compositional, structural and functional relationships. Methods: The rheology and composition was measured using Langmuir trough and 1H NMR spectroscopy, respectively. Results: MHSCT and Mn was studied from 16 to 43 donors, respectively, using NMR spectroscopy. MHSCT contained significantly 16% more straight chain and 24% less iso-chain hydrocarbons compared with Mn. The cholesteryl ester to wax ester molar ratio, and hydrocarbon chain unsaturation were not significantly different, for MHSCT compared with Mn. Surface pressure-area isotherms of meibum from 30 donors without dry-eye were grouped into 4 pools (PC) and meibum from 32 donors with dry eye who had hematopoietic stem cell transplantation (PT) were grouped into 3 pools. Above 15 years of age the Пmax and (Cs−1)max increased with age for both the PC and the PT cohorts. (Cs−1)max values were higher for PT samples compared with age matched PC samples, indicating they had higher elasticity and stiffness. A more ordered lipid could contribute to the formation of a discontinuous patchy tear film lipid layer, which in turn results in deteriorated spreading, and decreased surface elasticity. Conclusions: The composition and rheology of meibum from donors with dry eye and who have had HSCT support the idea from other studies that more ordered meibum may contribute to or be a marker of dry eye

Biophysical characteristics of tears in children

Purpose : The tear film forms an important part of our visual system and is essential for the functioning of the ocular surface. A stable tear film is required for preventing the most common ocular surface disease - dry-eye. Most of the studies on tears are conducted using samples from adult subjects and only few reports are available on tears of infants and children while it is known that infants and children have more stable tear film than adults. It is likely that nature of tears is different in children because dry-eye mainly occurs in adults. This study aimed at characterizing the biophysical characteristics of the tear film of children to look into tear film stability

Diagnostic stewardship : the impact of rapid diagnostic testing for paediatric respiratory presentations in the emergency setting : a systematic review

Antimicrobial resistance is a growing public health crisis, propelled by inappropriate antibiotic prescription, in particular the over-prescription of antibiotics, prolonged duration of antibiotic therapy and the overuse of broad-spectrum antibiotics. The paediatric population, in particular, those presenting to emergency settings with respiratory symptoms, have been associated with a high rate of antibiotic prescription rates. Further research has now shown that many of these antibiotic prescriptions may have been avoided, with more targeted diagnostic methods to identify underlying aetiologies. The purpose of this systematic review was to assess the impact of rapid diagnostic testing, for paediatric respiratory presentations in the emergency setting, on antibiotic prescription rates. To review the relevant history, a comprehensive search of Medline, EMBASE and Cochrane Database of Systematic Reviews was performed. Eighteen studies were included in the review, and these studies assessed a variety of rapid diagnostic testing tools and outcome measures. Overall, rapid diagnostic testing was found to be an effective method of diagnostic antibiotic stewardship with great promise in improving antibiotic prescribing behaviours. Further studies are required to evaluate the use of rapid diagnostic testing with other methods of antibiotics stewardship, including clinical decisions aids and to increase the specificity of interventions following diagnosis to further reduce rates of antibiotic prescriptio

Formaldehyde as an alternative to antibiotics for treatment of refractory impetigo and other infectious skin diseases

Introduction: Antibiotic-resistant strains of bacteria are an increasing problem in hospitals and in the community. This has resulted in bacterial infections such as impetigo becoming difficult to treat. Alternative treatment options are needed. Areas covered: In this paper, a past study that assessed the health burden of scabies in North Queensland is described and from it, the potential for formaldehyde as an alternative antimicrobial treatment is discussed. In doing so, antibiotic resistance, impetigo, permethrin, and formaldehyde are introduced and the current understanding and limitations of the effects of formaldehyde on humans are outlined. The limited cases of formaldehyde resistance in bacteria are also discussed. Expert opinion: Formaldehyde is currently used as a preservative in cosmetics and medicinal creams due to its antibacterial activity. It, therefore, has the potential to be used as an alternative antibacterial treatment for infections with antibiotic-resistant bacteria. The harmful side effects of airborne formaldehyde and exposure in allergic individuals have been extensively studied. Significantly less research has been conducted on formaldehyde skin contact in healthy individuals. If formaldehyde is safe for topical use in humans, it has the potential to assist with combating antibiotic resistance

The in vitro antibacterial effect of permethrin and formaldehyde on Staphylococcus aureus

Antibiotic‐resistant strains of bacteria such as methicillin‐resistant Staphylococcus aureus are a threat to human health, and effective treatment options against them are needed. This study aimed to determine whether the insecticide permethrin was capable of inhibiting the growth of S. aureus or if some other component of a permethrin cream was responsible for a decrease in scabies associated bacterial infection previously observed. Ten S. aureus strains were grown in the presence of permethrin and formaldehyde both alone and in combination with percent inhibition determined by viable counts. Also, a time‐kill assay was conducted on S. aureus exposed to the same conditions. Finally, the morphology of S. aureus grown in the presence of permethrin was examined by scanning electron microscopy. Bacterial inhibition by permethrin ranged from 0% to 41% whereas inhibition by formaldehyde was 100%. The time‐kill curves of permethrin exposed cells were very similar to the positive growth control while the formaldehyde and combination exposure showed complete inhibition even at the 0‐hr time point. The scanning electron micrographs of permethrin grown S. aureus showed healthy cocci cells with no sign of cell damage. Our results show that permethrin is not capable of inhibiting the growth of bacteria enough for it to be termed bactericidal. Formaldehyde is a known antiseptic and therefore was responsible for the antibacterial effect observed after the use of permethrin cream