Biomechanical Corneal Parameters in Eyes With Chronic Ocular Hypotony and in Non-Hypotonic Eyes. Self-Controlled Case Series Study

Rachid Bouchikh-El Jarroudi,1– 3,&ast; Kolbe Roche Fernández,1,4,&ast; Pau Romera Romero,1 Tatiana Croitoru-Croitoru,1 Anna Goñi-Guarro,1 Jessica Botella-Garcia,1 Antoni Sabala Llopart,1 Jordi Loscos-Arenas,1 Sebastian Videla5,6 1Service of Ophthalmology, Hospital Universitari Germans Trias i Pujol, Badalona, Spain; 2Department of Surgery, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain; 3Evidence Based Ophthalmology Unit (Oftalmoevidencia), Scientia Clinical and Epidemiological Research Institute, Trujillo, Peru; 4Department of Medicine, Universitat Autònoma de Barcelona (UAB), Barcelona, Spain; 5Clinical Research Support Area, Clinical Pharmacology Department, Hospital Universitari Germans Trias i Pujol, Badalona, Spain; 6Department of Pharmacology, Therapeutics and Toxicology. Autonomous University of Barcelona, Bellaterra, Spain&ast;These authors contributed equally to this workCorrespondence: Rachid Bouchikh-El Jarroudi, Hospital Universitari Germans Trias i Pujol, Carretera de Canyet, s/n, Badalona, Barcelona, 08916, Spain, Tel +34 689 14 80 84, Fax +34 934 97 88 43, Email [email protected]: There are no available data concerning corneal parameters in patients with chronic ocular hypotony. Our purpose is to provide evidence and clinical correlation on the biomechanical corneal changes in chronic hypotonic eyes.Patients and Methods: A single-center, transversal, self-controlled case series study was conducted involving patients with at least one chronic hypotonic eye (defined as an intraocular pressure ≤ 6.5 mmHg measured on three separate occasions for at least three months). The chronic hypotonic eye was the case and the contralateral eye the control (non-hypotonic eye). We collected data from baseline characteristic and intraocular pressure (mmHg). Biomechanical corneal parameters measured by Corvis ST: deformation amplitude ratio (mm), Ambrósio’s relational thickness (μm), stiffness parameter at first applanation (mmHg/mm), Integrated radius (mm− 1), stress-strain index, pachymetry (μm), and in addition macular folds were recorded as well. A descriptive and exploratory analysis was performed.Results: Between November 2021 and July 2023, a total of 16 consecutive patients (7 men, 9 women; age [median (range)]: 72 (62– 84)), diagnosed with chronic ocular hypotony in one eye were included: 16 chronic hypotonic eyes and 16 non-hypotonic eyes. Hypotonic versus non-hypotonic eyes [median (range)]: intraocular pressure: 4 (2– 6) mmHg, 16 (8– 38) mmHg; deformation amplitude ratio: 5.6 (4.3– 6.6) mm, 4.7 (3.9– 5.5) mm, p-value= 0.002; Ambrósio’s relational thickness: 482 (263– 932) μm, 530 (210– 818) μm, p-value: 0.845; stiffness parameter at first applanation: 61.5 (39– 100) mmHg/mm, 113 (68– 130) mmHg/mm, p-value: < 0.001; Integrated radius: 10.9 mm− 1 (6.3– 16.8), 7.9 mm− 1 (6.4– 10.5), p-value: < 0.001; stress-strain index: 0.7 (− 0.2– 4.9), 1.1 (− 2.7– 5.6), p-value: 0.034; pachymetry 509 (456– 617) μm, 512 (436– 775) μm, p-value: 0.637; and macular folds: 7/16, 0/16, p-value: < 0.001.Conclusions: Chronic hypotonic eyes (eyes with a low intraocular pressure) present biomechanical corneal changes with respect to non-hypotonic eyes, mainly in deformation amplitude ratio, stiffness parameter at first applanation, stress-strain index and Ambrósio’s relational thickness parameters. These biomechanical corneal changes could reflect softer, more elastic and deformable scleras, which at its turn can bear higher risk of hypotony maculopathy.Keywords: ocular hypotony, corneal biomechanics, macular fold

P2Y1 and P2Y12 receptor cross-talk in calcium signalling: Evidence from nonstarved and long-term serum-deprived glioma C6 cells

The current work presents results of experiments on the calcium response evoked by the stimulation by extracellular nucleotides occurring in control, nonstarved glioma C6 cells and in cells after long-term (96 h) serum starvation. Three nucleotide receptors were studied: P2Y1, P2Y2 and P2Y12. Two of them, P2Y1 and P2Y2, directly stimulate calcium response. The protein level of the P2Y2 receptor did not change during the serum starvation, while P2Y1 protein level fell dramatically. Observed changes in the calcium response generated by P2Y1 are directly correlated with the receptor protein level as well as with the amount of calcium present in the intracellular calcium stores, partially depleted during starvation process. The third receptor, P2Y12, did not directly evoke calcium response, however it is activated by the same ligand as P2Y1. The experiments with AR-C69941MX, the P2Y12-specific antagonist, indicated that in control and serum-starved cells, calcium response evoked by P2Y1 receptor is potentiated by the activity of P2Y12-dependent signaling pathways. This potentiation may be mediated by P2Y12 inhibitory effect on the plasma membrane calcium pump. The calcium influx enhanced by the cooperation of P2Y1 and P2Y12 receptor activity directly depends on the capacitative calcium entrance mechanism

In vivo glioblastoma growth is reduced by apyrase activity in a rat glioma model

BACKGROUND: ATP is an important signalling molecule in the peripheral and central nervous system. Both glioma growth and tumor resection induces cell death, thus liberating nucleotides to the extracellular medium. Nucleotides are hydrolyzed very slowly by gliomas when compared with astrocytes and induce neuronal cell death and glioma proliferation. The objective of the present study was to test the involvement of extracellular ATP in glioblastoma growth in a rat glioma model. METHODS: To deplete the extracellular ATP, the enzyme apyrase was tested on the treatment of gliomas implanted in the rats CNS. One million glioma C6 cells in 3 microliters of DMEM/FCS were injected in the right striata of male Wistar rats, 250–270 g. After 20 days, the rats were decapitated and the brain sectioning and stained with hematoxylin and eosine. We performed immunohistochemical experiments with Ki67, CD31 and VEGF. Total RNA was isolated from cultured glioma C6 cells and the cDNA was analyzed by Real Time-PCR with primers for the NTPDase family. RESULTS: C6 glioma cells effectively have a low expression of all NTPDases investigated, in comparison with normal astrocytes. The implanted glioma co-injected with apyrase had a significant reduction in the tumor size (p < 0.05) when compared with the rats injected only with gliomas or with gliomas plus inactivated apyrase. According to the pathological analysis, the malignant gliomas induced by C6 injection and co-injected with apyrase presented a significant reduction in the mitotic index and other histological characteristics that indicate a less invasive/proliferative tumor. Reduction of proliferation induced by apyrase co-injection was confirmed by counting the percentage of Ki67 positive glioma cell nuclei. According to counts with CD31, vessel density and neoformation was higher in the C6 group 20 days after implantation. Confirming this observation, rats treated with apyrase presented less VEGF staining in comparison to the control group. CONCLUSION: These results indicate that the participation of extracellular ATP and the ecto-nucleotidases may be associated with the development of this type of brain tumor in an in vivo glioma model

Two-site recognition of Staphylococcus aureus peptidoglycan by lysostaphin SH3b

Lysostaphin is a bacteriolytic enzyme targeting peptidoglycan, the essential component of the bacterial cell envelope. It displays a very potent and specific activity toward staphylococci, including methicillin-resistant Staphylococcus aureus. Lysostaphin causes rapid cell lysis and disrupts biofilms, and is therefore a therapeutic agent of choice to eradicate staphylococcal infections. The C-terminal SH3b domain of lysostaphin recognizes peptidoglycans containing a pentaglycine crossbridge and has been proposed to drive the preferential digestion of staphylococcal cell walls. Here we elucidate the molecular mechanism underpinning recognition of staphylococcal peptidoglycan by the lysostaphin SH3b domain. We show that the pentaglycine crossbridge and the peptide stem are recognized by two independent binding sites located on opposite sides of the SH3b domain, thereby inducing a clustering of SH3b domains. We propose that this unusual binding mechanism allows synergistic and structurally dynamic recognition of S. aureus peptidoglycan and underpins the potent bacteriolytic activity of this enzyme

Digital Communities as Online 'Gardens' for Memes: Metamorphic Narratives of Two Filipino 'Memeifiers' as Cultural Pollinators

The increasingly ubiquitous digital communities have become dynamic online social hubs for netizens to proliferate internet memes. While there have been an abundance of studies of memes, a dearth of investigations have examined how an internet user becomes an active producer of memes. Hence, we explored the narratives of two Filipino netizens, whom we call “memeifiers,” as we identified them as constant generators of memes. Based on the semi-structured interview data and analysis of their memes, we metaphorically posit that digital communities can be likened to online gardens where butterflies (memeifiers) dynamically engage in producing and pollinating memes. Using narrative configuration, we labelled their experiences into metamorphic narratives with three stages: (1) the cocoon stage, in which meme literacy is formed through active memes consumption; (2) the metamorphosis stage, in which meme-literate netizens vigorously generate memes then metamorphose into memeifiers; and finally, (3) the pollination stage, when memeifiers, akin to butterflies, continuously become cultural pollinators as they spread cultural artifacts through memes in various online communities. With these findings, we lay down some recommendations for future meme studies, such as that the metamorphic narrative of memeifiers be investigated in other geographical contexts since a memeifier’s story may vary due to cultural differences. Moreover, we recommend that the scope of participants be broadened, employing similar or other qualitative research designs and even quantitative perspectives to further scrutinize the metamorphosis of memeifiers and their roles as cultural pollinators. Keywords: digital communities, memes, narrative study, online communitie