Cytocompatibility of titanium and poly(etheretherketone) surfaces after O2 non-thermal plasma sterilization.

The sterilization of medical devices is paramount to achieve an acceptable level of sterility assurance and to prevent hospital-acquired infections. However, some medical devices cannot be sterilized by usual processes such as autoclave (AC) and gamma-ray irradiation (GI). A new non-thermal plasma (NTP) process using sealed bag that preserves the sterile state of the devices could be used as an alternative sterilization method. The aim of the study was to assess the cytocompatibility of titanium and poly(etheretherketone) (PEEK) surfaces after O2-NTP sterilization compared to GI and AC. MG-63 osteoblast-like cells were seeded on titanium (TA6V) and PEEK disks sterilized by AC, GI and O2-NTP. The cells' viability and proliferation, determined by WST-1 and DNA quantification respectively, were enhanced whatever the material types from 3 to 10 days. When seeded on titanium, MG-63 cells showed a higher viability and proliferation after GI and O2-NTP treatment compared to AC treatment. When cultured on PEEK, MG-63 cells showed a higher viability after O2-NTP treatment. No difference of proliferation was observed whatever the sterilization processes. The cell colonization of the materials' surface was confirmed by scanning electron microscopy. Lactate dehydrogenase (LDH) assay revealed no cytotoxicity. Thus, O2-NTP led to similar cell responses to AC and GI and could be a cost-effective alternative process to the usual sterilization methods for fragile medical devices.

A new de novo heterozygous missense mutation in the desmoplakin gene, causing Naxos and Carvajal disease, associating oligodontia and nail fragility.

A new de novo heterozygous mutation in the desmoplakin gene, causing Naxos and Carvajal disease, has been reported in a 13-year-old Caucasian girl, with expanded clinical phenotype. In addition to woolly hair, palmoplantar keratoderma and cardiomyopathy, she had oligodontia and nail fragility. These additional clinical features may help in the diagnosis of Naxos and Carvajal disease, known to be severe on the cardiac level.

Inactivation of Enveloped Bovine Viral Diarrhea Virus and Non-Enveloped Porcine Parvovirus Using Low-Pressure Non-Thermal Plasma.

As the worldwide population has been experiencing since 2020, viruses represent a serious threat to global well-being. To avoid viral transmission through surgery or medical examination, sterilization of medical material is needed. From emerging sterilization processes, the use of non-thermal plasma (NTP) arises as a promising technique to efficiently reduce microbial burden on medical devices, including new complex polymers as thermosensitive ones. Thus, we evaluated the antiviral efficacy of a low-pressure NTP process taking place in a sealed bag. For this purpose, two different plasmas, O2 100% plasma and Ar 80%-O2 20% plasma, were tested against two viruses: the bovine viral diarrhea virus and the porcine parvovirus, surrogates of human hepatitis C virus and human parvovirus B19, respectively. The efficacy of both NTP treatments on viral load can be detected after only five minutes. Moreover, the longer the NTP treatments last, the more the load decreases. The most effective load reduction was obtained with a 120-min O2 plasma treatment inducing a minimum of four-log viral load reduction. So, this process demonstrated strong virucidal capacity inside a sealed bag and represents a very interesting opportunity in the field of fragile medical devices sterilization or disinfection.

Contribution of Fluorescence Techniques in Determining the Efficiency of the Non-thermal Plasma Treatment.

We have recently developed a non-thermal plasma (NTP) equipment intended to sterilize fragile medical devices and maintain the sterile state of items downstream the treatment. With traditional counts on agar plate a six log reduction of Staphylococcus aureus viability was obtained within 120 min of O2, Ar, or N2 NTP treatments. However to determine the best NTP process, we studied the different physiological states of S. aureus by flow cytometry (FC) and confocal laser scanning microscopy (CLSM) focusing on the esterasic activity and membrane integrity of the bacteria. Two fluorochromes, 5-(and-6)-carboxy-2',7'-dichlorofluorescein diacetate and propidium iodide were used in order to distinguish three sub-populations: metabolically active, permeabilized, and damaged bacteria that can be in the viable but nonculturable state. FC and CLSM highlight that O2 and Ar NTP treatments were the most attractive processes. Indeed, a 5 min of Ar NTP generated a high destruction of the structure of bacteria and a 120 min of O2 NTP treatment led to the higher decrease of the total damaged bacteria population. SEM observations showed that in presence of clusters, bacteria of upper layers are easily altered compared to bacteria in the deeper layers. In conclusion, the plate counting method is not sufficient by itself to determine the best NTP treatment. FC and CLSM represent attractive indicator techniques to select the most efficient gas NTP treatment generating the lowest proportion of viable bacteria and the most debris.

Innovative non-thermal plasma disinfection process inside sealed bags: Assessment of bactericidal and sporicidal effectiveness in regard to current sterilization norms.

In this work, we developed a device capable to generate a non-thermal plasma discharge inside a sealed bag. The aim of this study was to assess the effectiveness of the oxygen, nitrogen and argon plasma sterilization on Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis spores according to the NF EN 556 Norm. Moreover the bag integrity which is a critical key to maintain the sterile state of items after the end of the process was verified by Fourier Transform Infrared (FTIR) and X-ray Photoelectron Spectrometry (XPS) analyses. After plasma treatments, the bacterial counting showed a 6 log reduction of P. aeruginosa and S. aureus in 45 min and 120 min respectively whatever the gas used and a 4 log reduction of B. subtilis spores in 120 min with only oxygen plasma. These results were confirmed by Scanning Electron Microscopy (SEM) observations showing altered bacteria or spores and numerous debris. Taking into account the studied microorganisms, the oxygen plasma treatment showed the highest efficiency. FTIR and XPS analyses showed that this treatment induced no significant modification of the bags. To conclude this non-thermal plasma sterilization technique could be an opportunity to sterilize heat and chemical-sensitive medical devices and to preserve their sterile state after the end of the process.

Mutations in the latent TGF-beta binding protein 3 (LTBP3) gene cause brachyolmia with amelogenesis imperfecta.

Inherited dental malformations constitute a clinically and genetically heterogeneous group of disorders. Here, we report on four families, three of them consanguineous, with an identical phenotype, characterized by significant short stature with brachyolmia and hypoplastic amelogenesis imperfecta (AI) with almost absent enamel. This phenotype was first described in 1996 by Verloes et al. as an autosomal recessive form of brachyolmia associated with AI. Whole-exome sequencing resulted in the identification of recessive hypomorphic mutations including deletion, nonsense and splice mutations, in the LTBP3 gene, which is involved in the TGF-beta signaling pathway. We further investigated gene expression during mouse development and tooth formation. Differentiated ameloblasts synthesizing enamel matrix proteins and odontoblasts expressed the gene. Study of an available knockout mouse model showed that the mutant mice displayed very thin to absent enamel in both incisors and molars, hereby recapitulating the AI phenotype in the human disorder.