The horizontal gene transfer of perchlorate reduction genomic island in three bacteria from an ecological niche.

Three new strains of dissimilatory perchlorate-reducing bacteria (DPRB), QD19-16, QD1-5, and P3-1, were isolated from an active sludge. Phylogenetic trees based on 16S rRNA genes indicated that QD19-16, QD1-5, and P3-1 belonged to Brucella, Acidovorax, and Citrobacter, respectively, expanding the distribution of DPRB in the Proteobacteria. The three strains were gram-negative and facultative anaerobes with rod-shaped cells without flagella, which were 1.0-1.6 µm long and 0.5-0.6 µm wide. The three DPRB strains utilized similar broad spectrum of electron donors and acceptors and demonstrated a similar capability to reduce perchlorate within 6 days. The enzyme activity of perchlorate reductase in QD19-16 toward chlorate was higher than that toward perchlorate. The high sequence similarity of the perchlorate reductase operon and chlorite dismutase genes in the perchlorate reduction genomic islands (PRI) of the three strains implied that they were monophyletic origin from a common ancestral PRI. Two transposase genes (tnp1 and tnp2) were found in the PRIs of strain QD19-16 and QD1-5, but were absent in the strain P3-1 PRI. The presence of fragments of IR sequences in the P3-1 PRI suggested that P3-1 PRI had previously contained these two tnp genes. Therefore, it is plausible to suggest that a common ancestral PRI transferred across the strains Brucella sp. QD19-16, Acidovorax sp. QD1-5, and Citrobacter sp. P3-1 through horizontal gene transfer, facilitated by transposases. These results provided a direct evidence of horizontal gene transfer of PRI that could jump across phylogenetically unrelated bacteria through transposase. KEY POINTS: • Three new DPRB strains can effectively remove high concentration of perchlorate. • The PRIs of three DPRB strains are acquired from a single ancestral PRI. • PRIs are incorporated into different bacteria genome through HGT by transposase.

Effects of surgical treatment modalities on postoperative cognitive function and delirium in elderly patients with extremely unstable hip fractures.

BACKGROUND: As the perioperative risk of elderly patients with extremely unstable hip fractures (EUHFs) is relatively high and therapeutic effect is not satisfactory, new thera-peutic strategies need to be proposed urgently to improve the efficacy and clinical outcomes of such patients. AIM: To determine the influence of two surgical treatment modalities on postoperative cognitive function (CF) and delirium in elderly patients with EUHFs. METHODS: A total of 60 elderly patients consecutively diagnosed with EUHF between September 2020 and January 2022 in the Chongqing University Three Gorges Hospital were included. Of them, 30 patients received conventional treatment (control group; general consultation + fracture type-guided internal fixation), and the other 30 received novel treatment (research group; perioperative multidisciplinary treatment diagnosis and treatment + individualized surgical plan + risk prediction). Information on hip function [Harris hip score (HHS)], perioperative risk of orthopedic surgery [Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity (POSSUM)], CF [Montreal cognitive assessment scale (MoCA)], postoperative delirium [mini-cognitive (Mini-Cog)], adverse events (AEs; internal fixation failure, infection, nonunion, malunion, and postoperative delirium), and clinical indicators [operation time (OT), postoperative hospital length of stay (HLOS), ambulation time, and intraoperative blood loss (IBL)] were collected from both groups for comparative analyses. RESULTS: The HHS scores were similar between both groups. The POSSUM score at 6 mo after surgery was significantly lower in the research group compared with the control group, and MoCA and Mini-Cog scores were statistically higher. In addition, the overall postoperative complication rate was significantly lower in the research than in the control group, including reduced OT, postoperative HLOS, ambulation time, and IBL. CONCLUSION: The new treatment modality has more clinical advantages over the conventional treatment, such as less IBL, faster functional recovery, more effectively optimized perioperative quality control, improved postoperative CF, mitigated postoperative delirium, and reduced operation-related AEs.

[Histological evaluations on periapical tissues after irradiation by erbium-doped yttrium aluminum garnet laser in Labradors dogs].

PURPOSE: To investigate the thermal effects on periapical tissues of Labrador dogs after intra-canal irradiation by erbium-doped yttrium aluminum garnet (Er:YAG) laser at different powers based on the antibacterial experiment of Enterococcus faecalis and Escherichia coli in root canals with an isthmus, to assess the histological changes, and to prove the safety for clinical applications. METHODS: Two hundred root canals of 10 healthy adult Labradors dogs were selected and divided into 5 groups. Excepted one as control group, root canals in other 4 groups were irradiated by Er:YAG laser with 1.5, 2.0, 2.5, 3.0 W for 30 s. Ten Labradors dogs were sacrificed at 0 (immediately after irradiation), 2 days, 2 weeks, 1 and 2 months. After preparation of pathological specimen, histological changes after laser irradiation in periapical tissues were evaluated and scores of inflammation were graded. Statistical analysis was performed using SPSS 13.0 software package. RESULTS: No significant difference was observed at the apical area between 1.5, 2.0, 2.5 W and control groups at most periods (P>0.05), whereas significant difference was observed between 3.0 W and other groups for all periods (P<0.05). CONCLUSIONS: These results suggest that if proper output powers (2.0-2.5 W) of laser irradiation are chosen, disinfection in root canals can be finished successfully and thermal effects on the periapical tissues can be minimized.

[Evaluation of root canal isthmus debridement efficacy of Er:YAG laser in combination with sodium hypochlorite].

PURPOSE: To histologically evaluate the efficacy of sodium hypochlorite (NaClO) in combination with Er:YAG (erbium-doped yttrium aluminium garnet) laser in dissolving necrotic tissue and cleaning root canals as well as canal isthmuses. METHODS: After scanned by cone-beam CT (CBCT), 50 well-prepared premolars with root canal isthmuses were selected and randomly assigned into 5 groups. They were subsequently subjected to different regimens as followed: group A-irrigated with 1% NaClO for 1 minute, group B- irradiated by Er:YAG laser at 0.5 W combined with 1% NaClO irrigation for 1 minute, group C- irradiated by Er:YAG laser at 1.0 W combined with 1% NaClO irrigation for 1 minute, group D- irradiated by Er:YAG laser at 2.0 W combined with 1% NaClO irrigation for 1 minute,group E- negative control. After histological preparation and staining, the cross-sections were evaluated for percentage of tissue removal from root canals and isthmuses. The cleanliness values were calculated using SPSS 13.0 software package. RESULTS: The mean percentage of root canals in group A, B, C and D was 95.24%, 96.53%、97.63% and 98.22%, respectively, and the mean percentage of isthmuses was 16.50%, 51.48%, 52.56% and 53.83%, respectively. The mean percentage of root canal and isthmus cleanliness values were significantly higher in group B, C and D (P<0.05) than that in group A. There was no significant differences of root canal and isthmus cleanliness among group B, C and D. CONCLUSIONS: Er:YAG laser combined with 1% NaClO irrigation may be used effectively in root canal and root canal isthmus cleanliness as a new method.

Biomechanical comparison of anterior lumbar screw-plate fixation versus posterior lumbar pedicle screw fixation.

Anterior lumbar interbody fusion (ALIF) followed by posterior pedicle screw fixation (PSF) in a second procedure is mostly used to implement lumbar spine fusion. ALIF followed by anterior lumbar screw-plate has a lot of advantages, but its biomechanical stability requires confirmation. This study evaluated the biomechanical stability of a novel anterior lumbar locked screw-plate (ALLSP) by comparison with posterior lumbar PSF. Twelve fresh human cadaveric lumbar specimens (L4-L5) were assigned to four groups: ALIF+PSF group, ALIF+ALLSP (both fixed) group, ALIF group and an untreated control (both non-fixed) group. The first three groups received implantation of a rectangular titanium cage. Tests under axial compression, flexion, extension, lateral bending, or rotation showed that the fixed groups had significantly stronger stability than the non-fixed groups (P=0.000 for all). The ALIF+ALLSP group had significantly greater axial stiffness under applied axial compression and significantly less angular displacement under rotational forces than the ALIF+PSF group. The angular displacement of the ALIF+ALLSP group was less under flexion than that of the ALIF+PSF, and the angular displacement under lateral bending and extension was greater, but these differences were not statistically significant. In summary, the ALLSP conforms to the anterior lumbar spine and has good biomechanical stability. It is a reliable choice for enhancing the stability of ALIF.