Effect of angiotensin II on irradiation exacerbated decompression sickness.

In some complicated situations, decompression sickness (DCS) combined with other injuries, such as irradiation, will seriously endanger life safety. However, it is still unclear whether irradiation will increase the incidence of DCS. This study was designed to investigate the damage effects of irradiation on decompression injury and the underlying mechanism. Sprague-Dawley rats were exposed to irradiation followed by hyperbaric decompressing and the mortality and decompression symptoms were observed. Lung tissue and bronchoalveolar lavage fluid were collected to detect the lung lesion, inflammation response, activity of the angiotensin system, oxidative stress, and relative signal pathway by multiple methods, including Q-PCR, western blot, and ELISA. As a result, pre-exposure to radiation significantly exacerbated disease outcomes and lung lesions of DCS. Mechanically, the up-regulation of angiotensin-converting enzyme expression and angiotensin II levels was responsible for the exacerbated DCS and lung lesions caused by predisposing irradiation exposure. Oxidative stress and PI3K/AKT signal pathway activation in pulmonary tissue were enhanced after irradiation plus decompression treatment. In conclusion, our results suggested that irradiation could exacerbate lung injury and the outcomes of DCS by activating the angiotensin system, which included eliciting oxidative stress and activation of the PI3K/AKT signal pathway.

Varied effects exerted on sudden sensorineural hearing loss through HBO2 therapeutic pressure.

This study aimed to compare the efficacy of two commonly used therapeutic pressures, 2.0 atmospheres absolute (ATA) versus 2.2 ATA, applied in hyperbaric oxygen (HBO2) therapy for sudden sensorineural hearing loss (SSNHL). We retrospectively reviewed the clinical records of 160 SSNHL patients treated by typical therapy or additional HBO2 therapy with pressure 2.0 or 2.2 ATA at Yijishan Hospital, the First Affiliated Hospital of Wannan Medical College, from February 2018 to May 2020. The pure-tone threshold audiometry results pre- and post-treatment were compared across three groups. In the range of frequencies 250-500 Hz, P2.0 (20.92±26.11 dB, p=0.047) and P2.2 group (20.47±±21.54 dB, p=0.012) both acquired higher hearing gain compared to the control group (11.94±23.32 dB). While in the range of frequencies 1,000-2,000 Hz, only the P2.2 group showed significant improvement of the hearing gain compared to the control group (19.70±21.13 dB vs.10.56±25.24 dB, p=0.015). In the range of frequencies 4,000-8,000, both the P2.0 and P2.2 groups failed to reach the desired effect. Our results suggest that the therapeutic effect is associated with HBO2 therapeutic pressure when applying HBO2 treatment combined with standard medical therapy. Within the range of appropriate pressure, the higher pressure, which means higher partial pressure of oxygen, has better therapeutic efficacy for SSNHL.

Multilocus sequencing typing of Pseudomonas aeruginosa isolates and analysis of potential pathogenicity of typical genotype strains from occupational oxyhelium saturation divers.

BACKGROUND: Pseudomonas aeruginosa (P. aeruginosa) is a common microbe isolated from divers with ear and skin infections. To obtain the epidemic characters of the occurrence of the P. aeruginosa infection, multilocus sequence typing (MLST) was used to assess the genetic background of different strains isolated from divers involved in saturation diving. METHODS: A total of 64 P. aeruginosa strains from naval divers were sequenced by multilocus sequence typing using seven housekeeping genes (acsA, aroE, guaA, mutL, nuoD, ppsA and trpE). The results were analyzed based on the P. aeruginosa international MLST database to obtain the allelic profiles and sequence types (STs). MLST data were analyzed by Bionumerics 4.0 (http: // pubmlst.org/mlstanalyse) using LIAN and eBURST. Twenty-eight strains with the typical genotype were selected for further analysis of pathogenic characteristics by Caenorhabditis elegans (C. elegans) fast killing model. RESULTS: Data from MLST revealed a high STs diversity among the strains. Of the 64 strains, 53 strains were assigned to 19 STs, and the remaining 11 clones could not be assigned. ST274 accounted for 18.5% (12/64), and ST260 accounted for 15.62% (10/64). C. elegans killing assay showed that all the test strains had distinct virulent properties as compared with the negative control group. Clone 503-1 had the highest virulence and clone 54 had the lowest virulence as compared with the positive clinical group. CONCLUSION: The P. aeruginosa strains carried by the occupational diver groups in Chinese regions have characteristically dominant STs, and have a relatively strong virulence as compared with the standard strain and the clinically isolated positive control strain.

Microarray analysis and phenotypic response of Pseudomonas aeruginosa PAO1 under hyperbaric oxyhelium conditions.

Pseudomonas aeruginosa is an important opportunistic pathogen associated with multiple diseases including cystic fibrosis and nosocomial infections. Pseudomonas aeruginosa is also the microbe most often isolated from ear and skin infections in divers. Saturation divers often suffer from various skin and mucous disorders, of which P. aeruginosa infections are the most serious and frequent. Previous studies mainly focused on adaptive and regulatory mechanisms of P. aeruginosa virulence in inducing clinical acute and chronic infections under different environmental conditions. However, there are few studies describing the physiological adaptive and regulatory mechanisms of P. aeruginosa in inducing high infectivity in healthy divers under hyperbaric oxyhelium conditions and even fewer studies describing the overall influence of the hyperbaric oxyhelium environment on regulating mRNA and protein expression levels of P. aeruginosa. The present study used transcriptomic and virulence phenotype analysis to identify factors that allow P. aeruginosa to become established in a hyperbaric oxyhelium environment to facilitate infections in divers. Transcriptional profiling of P. aeruginosa grown under steady-state hyperbaric oxyhelium stress conditions showed an upregulation of genes associated with stress-sense/response, protein folding, transcriptional regulation, pili and flagellum metabolism, virulence adaptation, and membrane protein metabolism. Some of these genes (including several two-component systems not previously known to be influenced by hyperbaric oxyhelium) were differentially expressed by P. aeruginosa in response to 72 h of exposure to hyperbaric oxyhelium stress. Detection of the virulence phenotype confirmed the results of cDNA microarrays. Based on these results, we conclude that hyperbaric oxyhelium conditions affect PAO1 gene expression and upregulate the expression of most virulence genes. The data obtained in our study may provide new insight into the molecular mechanism of hyperbaric oxyhelium exposure against P. aeruginosa virulence adaptation.