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Bacteria
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Components in cell envelopes are important in host-parasite interactions. LPS is an important virulence factor. For example, Neisseria meningitidis, a Gram-negative bacterium, causes the diseases meningitis and bacteremia in humans; sometimes accompanied by septic shock, a process that is induced by LPS from the organism. Many of the proteins and polysaccharides in cell walls are antigenic or act as haptens in immunological reactions. Detection of these antigens often aids in the diagnosis of infections. For example, detection of LPS indicates infection with a Gram-negative bacterium. The lipid A is the part of LPS that is primarily responsible for the endotoxemia that is associated with many Gram-negative bacterial infections. Antibiotic treatment often results in liberation of LPS from the bacteria following their lysis. As a result, clinical endotoxemia symptoms may develop after treatment with antibiotics, also, many commercial foods, bottled water, as well as sterile water used for intravenous applications are routinely analyzed for LPS to assure the absence of these virulence factors.
Chemical Structure of Lipid A: Recent Advances in Structural Analysis of Biologically Active Molecules
Published in Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison, Endotoxin in Health and Disease, 2020
Ulrich Zähringer, Buko Lindner, Ernst T. Rietschel
Lipopolysaccharides (LPS) of gram-negative bacteria are composed of three genetically and structurally distinct regions: the O-antigenic polysaccharide (O-specific chain); the core oligosaccharide; and a lipophilic portion, termed lipid A, which anchors the LPS molecule to the bacterial outer membrane (1,2). Lipid A was first described in 1954 by Westphal and Lüderitz as a hydrophobic water-insoluble precipitate obtained on acid treatment of LPS (3). The term lipid A was introduced in order to distinguish it from a further LPS-associated lipid B investigated at that time by Morgan and Partridge (4), which was later identified as phosphatidylethanolamine (5).
Cardiology
Published in Keith Hopcroft, Instant Wisdom for GPs, 2017
Lipid profiles are one of the most commonly requested blood tests from general practice. Before reaching for the prescription pad, consider some important possible underlying causes. These include lifestyle factors such as excessive alcohol intake (raised triglycerides), a diet rich in saturated fats (total cholesterol, TG), sedentary lifestyle and cigarette smoking (low HDL) as well as a number of systemic illnesses including hypothyroidism, diabetes mellitus, primary biliary cirrhosis and nephrotic syndrome. Finally, drugs such as antiretroviral agents, retinoids, cyclosporin and corticosteroids may also result in adverse lipid profiles.
Investigation of dimyristoyl phosphatidyl glycerol and cholesterol based nanocochleates as a potential oral delivery carrier for methotrexate
Published in Journal of Liposome Research, 2022
Bothiraja Chellampillai, Sneha Kashid, Atmaram Pawar, Ashwin Mali
The DMPG-Na was selected for the formulation of nanoliposomes. The various types of nanocochleates such as rolled, cylindrical, spherical and planar have been reported by using several acidic phospholipids (Zarif 2005). The anionic saturated phospholipid with two 14C atoms chains was widely reported for the preparation of nanocochleates. This lipid represents the major component of membranes of gram-positive bacteria (Umeyama et al. 2006). Further, cholesterol has the ability to form complexes with drugs as well as to stabilise the phospholipid membranes, followed by encapsulation of MTX (Poudel et al. 2018). The NLs were prepared to have an increasing amount of MTX (3, 5 and 7mg) to achieve maximum loading of MTX into the lipid bilayers and were evaluated for particle size and encapsulation efficiency. The NLs size was increased in proportion to MTX concentration which was ranging from 3mg (MTX-NL1) to 5mg (MTX-NL2) as depicted in Table 1. But, the gradual increase in terms of 7mg (MTX-NL3) resulted in low encapsulation efficiency.
Potential utility of nano-based treatment approaches to address the risk of Helicobacter pylori
Published in Expert Review of Anti-infective Therapy, 2022
Sohaib Khan, Mohamed Sharaf, Ishfaq Ahmed, Tehsin Ullah Khan, Samah Shabana, Muhammad Arif, Syed Shabi Ul Hassan Kazmi, Chenguang Liu
A recent study reported that pectin-coated liposomes encapsulated with amoxicillin have shown anti-adhesive properties against H. pylori [160]. Similar studies were conducted to produce lipid-polymer hybrid NPs loaded with either clarithromycin or amoxicillin and applied them to gastric delivery [161,162]. Both studies demonstrated the elimination of EPS and destruction of H. pylori biofilm, and this was interesting to know the role of biosurfactant rhamnolipids that exhibited strong anti-biofilm activity due to its amphiphilic properties. Lipid NPs have shown flexibility that can offer an excellent platform for the delivery of various antimicrobial agents. In addition, the effects of liposomal linolenic acid with triple therapy treatment on the gastrointestinal microbiota of mice were also observed. The results concluded that there were dramatic changes triggered by triple therapy as compared to the liposomal linolenic acid that caused a minor effect. This implies the effectiveness and safety of the liposomal linolenic acid medication for the eradication of H. pylori [163], and the in vitro reduction in the colonization of H. pylori [164].
A mechanistic perspective on targeting bacterial drug resistance with nanoparticles
Published in Journal of Drug Targeting, 2021
Khatereh Khorsandi, Saeedeh Keyvani-Ghamsari, Fedora Khatibi Shahidi, Reza Hosseinzadeh, Simab Kanwal
An asymmetric lipid bilayer of the outer membrane makes it an unusual structure, with an outer leaflet composed of LPS and an inner leaflet containing phospholipids [30]. LPS is glucosamine-based glycolipid including three sections: the membrane anchor lipid A, a short core oligosaccharide and a very changeable O-antigen polysaccharide [31]. Lipid A is an ‘endotoxin’ that induces the inherent immune response, enhances pro-inflammatory cytokine release and consequently produces various dramatic symptoms related to systemic Gram-negative infections such as fever and sepsis [32]. Gram-negative O-antigen commonly generates a powerful antibody reaction, which can result in a later infection [33]. Other Gram-negative outer membrane individual features involve lipoproteins and integral membrane proteins (outer membrane proteins) which are inserted in the outer membrane [34]. Receiving nutrients and discharging waste products are also functions of outer membrane proteins that have channel structures. The outer membrane can also contain other glycolipids like an enterobacterial common antigen which is specific in E. coli [35,36]. The outer membrane also has binding site for superficial organelles, such as pili, that are responsible for bacterial surface adherence [37].