Blood-Ocular Barriers

Chen, Muh‐Shy; Hou, Ping-Kang; Tai, Tong Yuan; Lin, Boniface J.

doi:10.1016/s1016-3190(08)60004-x

Cited by 28 publications

(15 citation statements)

References 40 publications

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“…The barrier system separates the interior portion of the eye from blood entering the eye and maintains the transparency and function of the interior portion of the eye. There are two main blood-ocular barriers, the blood aqueous barrier and the blood retinal barrier, a barrier to the free diffusion of molecules formed by tight junctions (18,30). During experimental B. cereus endophthalmitis, Moyer et al (102) showed that the bacterium causes a permeability of the blood-retinal barrier as early as 4 h postinfection by the disruption of tight junctions between endothelial cells and the basement membrane of retinal capillaries and retinal pericytes.…”

Section: Blood-ocular Barriermentioning

confidence: 99%

Bacillus cereus , a Volatile Human Pathogen

2010

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SUMMARY Bacillus cereus is a Gram-positive aerobic or facultatively anaerobic, motile, spore-forming, rod-shaped bacterium that is widely distributed environmentally. While B. cereus is associated mainly with food poisoning, it is being increasingly reported to be a cause of serious and potentially fatal non-gastrointestinal-tract infections. The pathogenicity of B. cereus, whether intestinal or nonintestinal, is intimately associated with the production of tissue-destructive exoenzymes. Among these secreted toxins are four hemolysins, three distinct phospholipases, an emesis-inducing toxin, and proteases. The major hurdle in evaluating B. cereus when isolated from a clinical specimen is overcoming its stigma as an insignificant contaminant. Outside its notoriety in association with food poisoning and severe eye infections, this bacterium has been incriminated in a multitude of other clinical conditions such as anthrax-like progressive pneumonia, fulminant sepsis, and devastating central nervous system infections, particularly in immunosuppressed individuals, intravenous drug abusers, and neonates. Its role in nosocomial acquired bacteremia and wound infections in postsurgical patients has also been well defined, especially when intravascular devices such as catheters are inserted. Primary cutaneous infections mimicking clostridial gas gangrene induced subsequent to trauma have also been well documented. B. cereus produces a potent β-lactamase conferring marked resistance to β-lactam antibiotics. Antimicrobials noted to be effective in the empirical management of a B. cereus infection while awaiting antimicrobial susceptibility results for the isolate include ciprofloxacin and vancomycin.

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Section: Blood-ocular Barriermentioning

confidence: 99%

Bacillus cereus , a Volatile Human Pathogen

2010

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“…However, the blood-ocular barrier also prevents most drugs from entering the eye and hinders targeted medical therapies (e.g., ocular tumor-related treatments)10. Han et al 11 reported that BMs can pass through the blood-brain barrier, which is similar in structure and function to the blood-ocular barrier, and carry genes to treat brain tumors.…”

mentioning

confidence: 99%

“…The eye is a fragile organ and is protected by the blood-ocular barrier, which is created by the endothelium of the capillaries of the retina and iris, ciliary epithelium and retinal pigment epithelium. However, the blood-ocular barrier also prevents most drugs from entering the eye and hinders targeted medical therapies (e.g., ocular tumor-related treatments) 10 . Han et al 11 reported that BMs can pass through the blood-brain barrier, which is similar in structure and function to the blood-ocular barrier, and carry genes to treat brain tumors.…”

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confidence: 99%

Cytotoxicity and genotoxicity of bacterial magnetosomes against human retinal pigment epithelium cells

Zhang

et al. 2016

Sci Rep

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A variety of nanomaterials have been developed for ocular diseases. The ability of these nanomaterials to pass through the blood-ocular barrier and their biocompatibility are essential characteristics that must be considered. Bacterial magnetosomes (BMs) are a type of biogenic magnetic nanomaterials synthesized by magnetotactic bacteria. Due to their unique biomolecular membrane shell and narrow size distribution of approximately 30 nm, BMs can pass through the blood-brain barrier. The similarity of the blood-ocular barrier to the blood-brain barrier suggests that BMs have great potential as treatments for ocular diseases. In this work, BMs were isolated from magnetotactic bacteria and evaluated in various cytotoxicity and genotoxicity studies in human retinal pigment epithelium (ARPE-19) cells. The BMs entered ARPE-19 cells by endocytosis after a 6-h incubation and displayed much lower cytotoxicity than chemically synthesized magnetic nanoparticles (MNPs). MNPs exhibited significantly higher genotoxicity than BMs and promoted the expression of Bax (the programmed cell death acceleration protein) and the induction of greater cell necrosis. In BM-treated cells, apoptosis tended to be suppressed via increased expression of the Bcl-2 protein. In conclusion, BMs display excellent biocompatibility and potential for use in the treatment of ocular diseases.

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“…The BAB consists of non-pigmented epithelium of the ciliary body, the posterior iris epithelium, and the iris vessel and Schlemm's canal endothelium. 57 It is responsible for providing nutrition to the lens and cornea. The ciliary body regulates the BAB.…”

Section: Barriers Around the Vhmentioning

confidence: 99%

“…59 There is an active transport from the VH to the retinal vessels and a passive transport from the BRB into the VH. 57 An increase of glucose transport from retinal vessels into the VH occurs in patients with diabetes. 58 A high passive transport level can be correlated to the degree of retinopathy, which is a direct effect of the breakdown of the BRB.…”

Section: Barriers Around the Vhmentioning

confidence: 99%

The regional distribution and molecular interactions of phospholipids and glucose in mammalian vitreous humors.

Schnepf¹

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The vitreous humor (VH) is located in between the lens and the retina. It is composed of 98% water, hyaluronan (HA), collagen, proteins, phospholipids (PLs), and other metabolites. With aging, the VH undergoes liquefaction, a process that causes the gel-like structure of the VH to turn into a liquid and can lead to serious ocular diseases, including retinal detachment, vitreal detachment, and macular hole formation. The liquefaction process is expedited in diabetic VHs. This project focuses on understanding the molecular changes that lead to liquefaction and the reasons for which this process is accelerated with diabetes. Matrix-assisted laser desorption ionization/mass spectrometry (MALDI/MS) and nuclear magnetic resonance (NMR) spectroscopy were applied for in vitro, ex situ, and model studies of VHs to identify and quantify several components of the VH network and explore their interactions. In-vitro and ex-situ methods were optimized and conducted on porcine and human VHs. The mammalian species produced similar compositional trends. MALDI/MS showed that PLs were most abundant in the posterior region (closest to the retina) followed by the anterior (closest to the lens) and then the central regions. Diabetic and non-diabetic VHs regional distribution of glucose was compared. Glucose was vi present in significant higher levels (three-fold) in diabetic VHs compared to non-diabetic ones of similar age. The levels of glucose in the diabetic VH were highest in the posterior followed by the anterior and central regions. This trend follows that observed for the PLs. Model studies were performed to explore the interaction(s) of vitreal components and hyaluronan (HA) using MALDI/MS and NMR. The studies indicate interactions between both the headgroups of PLs and the carboxylate groups of HA as well as that between the acyl tails on PC with the hydrophobic regions of HA. Such interactions are proposed to disrupt the H-bonding network of HA and contribute to liquefaction of the VH. Future studies will focus on age-dependent studies of human VHs as well as the analysis of fresh human VHs following vitrectomy surgery. vii

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Blood-Ocular Barriers

Cited by 28 publications

References 40 publications

Bacillus cereus , a Volatile Human Pathogen

Bacillus cereus , a Volatile Human Pathogen

Cytotoxicity and genotoxicity of bacterial magnetosomes against human retinal pigment epithelium cells

The regional distribution and molecular interactions of phospholipids and glucose in mammalian vitreous humors.

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