Burkholderia collagen-like protein 8, Bucl8, is a unique outer membrane component of a putative tetrapartite efflux pump in Burkholderia pseudomallei and Burkholderia mallei.

Bacterial efflux pumps are an important pathogenicity trait because they extrude a variety of xenobiotics. Our laboratory previously identified in silico Burkholderia collagen-like protein 8 (Bucl8) in the hazardous pathogens Burkholderia pseudomallei and Burkholderia mallei. We hypothesize that Bucl8, which contains two predicted tandem outer membrane efflux pump domains, is a component of a putative efflux pump. Unique to Bucl8, as compared to other outer membrane proteins, is the presence of an extended extracellular region containing a collagen-like (CL) domain and a non-collagenous C-terminus (Ct). Molecular modeling and circular dichroism spectroscopy with a recombinant protein, corresponding to this extracellular CL-Ct portion of Bucl8, demonstrated that it adopts a collagen triple helix, whereas functional assays screening for Bucl8 ligands identified binding to fibrinogen. Bioinformatic analysis of the bucl8 gene locus revealed it resembles a classical efflux-pump operon. The bucl8 gene is co-localized with downstream fusCDE genes encoding fusaric acid (FA) resistance, and with an upstream gene, designated as fusR, encoding a LysR-type transcriptional regulator. Using reverse transcriptase (RT)-qPCR, we defined the boundaries and transcriptional organization of the fusR-bucl8-fusCDE operon. We found exogenous FA induced bucl8 transcription over 80-fold in B. pseudomallei, while deletion of the entire bucl8 locus decreased the minimum inhibitory concentration of FA 4-fold in its isogenic mutant. We furthermore showed that the putative Bucl8-associated pump expressed in the heterologous Escherichia coli host confers FA resistance. On the contrary, the Bucl8-associated pump did not confer resistance to a panel of clinically-relevant antimicrobials in Burkholderia and E. coli. We finally demonstrated that deletion of the bucl8-locus drastically affects the growth of the mutant in L-broth. We determined that Bucl8 is a component of a novel tetrapartite efflux pump, which confers FA resistance, fibrinogen binding, and optimal growth.

Hemodynamic and Laboratory Changes during Incremental Transition from Twice to Thrice-Weekly Hemodialysis.

OBJECTIVE: Incremental hemodialysis (HD) is a strategy utilized to gradually intensify dialysis among patients with incident end-stage renal disease. However, there are scarce data about which patients' clinic status changes by increasing treatment frequency. METHODS: We retrospectively examined statistically de-identified data from 569 patients who successfully transitioned from twice- to thrice-weekly HD (2007-2011) and compared the differences in monthly-averaged values of hemodynamic and laboratory indices during the 3 months before and after the transition with the values at 1 month prior to transition serving as the reference. RESULTS: At 3 months after transitioning from twice- to thrice-weekly HD, ultrafiltration volume decreased by 0.5 (95% CI 0.3-0.6) L/session among 189 patients (33%) with weekly interdialytic weight gain (IDWG) ≥5.4 kg/week, and increased by 0.4 (95% CI 0.3-0.5) L/session among 186 patients (33%) with weekly IDWG <3.3 kg/week. Weekly IDWG consistently increased after the transition irrespective of baseline values (1.7 [95% CI 1.5-1.9] kg/week). Pre-HD systolic blood pressure (SBP) decreased by 12 (95% CI 9-14) mm Hg among 177 patients (31%) with baseline pre-HD SBP ≥160 mm Hg, which coincided with a decreasing trend in post-HD body weight (1.3 [95% CI 0.8-1.7] kg). DISCUSSION: In conclusion, patients who increased HD frequency from twice to thrice weekly treatment experienced increased weekly IDWG and better pre-HD SBP control with lower post-HD body weight.

Improvement in postoperative pain control by combined use of intravenous dexamethasone with intravenous dexmedetomidine after interscalene brachial plexus block for arthroscopic shoulder surgery: A randomised controlled trial.

BACKGROUND: Intravenous dexamethasone or dexmedetomidine is reported to prolong the duration of analgesia after single-shot interscalene brachial plexus block (ISBPB). However, the effect of co-administration of these agents on the duration of analgesia has not been evaluated. OBJECTIVES: We evaluated the difference in time to first rescue analgesic request between patients receiving co-administered intravenous dexamethasone and dexmedetomidine and patients receiving intravenous dexamethasone alone after single-shot ISBPB for arthroscopic shoulder surgery. DESIGN: A randomised controlled study. SETTING: A single tertiary care centre, study period from August 2017 to January 2018. PATIENTS: Sixty-six patients undergoing arthroscopic shoulder surgery with ISBPB with 15 ml of 0.5% ropivacaine with 1 : 200 000 epinephrine. INTERVENTIONS: We randomly assigned the patients to one of three groups: intravenous 0.9% saline (control), intravenous dexamethasone 0.11 mg kg (D1 group), or co-administered intravenous dexamethasone 0.11 mg kg and intravenous dexmedetomidine 1.0 µg kg (D2 group). MAIN OUTCOME MEASURES: The primary outcome was the time to first rescue analgesic request. RESULTS: The median [interquartile range] time to first rescue analgesic request was significantly longer for the D2 group (66.3 h [23.3 to 72]) than the D1 (17.4 h [14.9 to 36], P = 0.002) and control (10.9 h [10.1 to 12.2], P < 0.001) groups. The D1 and D2 groups both had reduced pain scores, reduced postoperative opioid consumption, less sleep disruption and improved patient satisfaction compared with the control group. There were no significant elevations in blood glucose concentrations in patients receiving dexamethasone (D1 and D2 groups) compared with the control group at postoperative day 1. CONCLUSION: Co-administration of intravenous dexamethasone (0.11 mg kg) with dexmedetomidine (1.0 µg kg) significantly prolonged the time to first rescue analgesic request after single-shot ISBPB in patients undergoing arthroscopic shoulder surgery. TRIAL REGISTRATION: Clinical Trial Registry of Korea; https://cris.nih.go.kr/cris/index.jsp and identifier: KCT0002569.

Unique Footprint in the scl1.3 Locus Affects Adhesion and Biofilm Formation of the Invasive M3-Type Group A Streptococcus.

The streptococcal collagen-like proteins 1 and 2 (Scl1 and Scl2) are major surface adhesins that are ubiquitous among group A Streptococcus (GAS). Invasive M3-type strains, however, have evolved two unique conserved features in the scl1 locus: (i) an IS1548 element insertion in the scl1 promoter region and (ii) a nonsense mutation within the scl1 coding sequence. The scl1 transcript is drastically reduced in M3-type GAS, contrasting with a high transcription level of scl1 allele in invasive M1-type GAS. This leads to a lack of Scl1 expression in M3 strains. In contrast, while scl2 transcription and Scl2 production are elevated in M3 strains, M1 GAS lack Scl2 surface expression. M3-type strains were shown to have reduced biofilm formation on inanimate surfaces coated with cellular fibronectin and laminin, and in human skin equivalents. Repair of the nonsense mutation and restoration of Scl1 expression on M3-GAS cells, restores biofilm formation on cellular fibronectin and laminin coatings. Inactivation of scl1 in biofilm-capable M28 and M41 strains results in larger skin lesions in a mouse model, indicating that lack of Scl1 adhesin promotes bacterial spread over localized infection. These studies suggest the uniquely evolved scl1 locus in the M3-type strains, which prevents surface expression of the major Scl1 adhesin, contributed to the emergence of the invasive M3-type strains. Furthermore these studies provide insight into the molecular mechanisms mediating colonization, biofilm formation, and pathogenesis of group A streptococci.

A Unique Set of the Burkholderia Collagen-Like Proteins Provides Insight into Pathogenesis, Genome Evolution and Niche Adaptation, and Infection Detection.

Burkholderia pseudomallei and Burkholderia mallei, classified as category B priority pathogens, are significant human and animal pathogens that are highly infectious and broad-spectrum antibiotic resistant. Currently, the pathogenicity mechanisms utilized by Burkholderia are not fully understood, and correct diagnosis of B. pseudomallei and B. mallei infection remains a challenge due to limited detection methods. Here, we provide a comprehensive analysis of a set of 13 novel Burkholderia collagen-like proteins (Bucl) that were identified among B. pseudomallei and B. mallei select agents. We infer that several Bucl proteins participate in pathogenesis based on their noncollagenous domains that are associated with the components of a type III secretion apparatus and membrane transport systems. Homology modeling of the outer membrane efflux domain of Bucl8 points to a role in multi-drug resistance. We determined that bucl genes are widespread in B. pseudomallei and B. mallei; Fischer's exact test and Cramer's V2 values indicate that the majority of bucl genes are highly associated with these pathogenic species versus nonpathogenic B. thailandensis. We designed a bucl-based quantitative PCR assay which was able to detect B. pseudomallei infection in a mouse with a detection limit of 50 CFU. Finally, chromosomal mapping and phylogenetic analysis of bucl loci revealed considerable genomic plasticity and adaptation of Burkholderia spp. to host and environmental niches. In this study, we identified a large set of phylogenetically unrelated bucl genes commonly found in Burkholderia select agents, encoding predicted pathogenicity factors, detection targets, and vaccine candidates.

The effects of desflurane and sevoflurane on hepatic and renal functions after right hepatectomy in living donors*.

We compared postoperative hepatic and renal functions between the two inhalational anesthetics, desflurane and sevoflurane in living donors undergoing right hepatectomy. Seventy-four adult donors were randomly allocated into Des group (n = 37) and sevo group (n = 37). Before the induction of anesthesia, morphine sulfate 400 microg was injected intrathecally. Anesthesia was maintained with one minimum alveolar concentration (MAC) of deflurane or sevoflurane plus continuous intravenous remifentanil. Liver and renal function tests were performed and analysed at preoperative period, immediately after operation, and on 1st, 2nd, 3rd, 5th, 7th, and 30th postoperative days (PODs). Aspartate aminotransferase (AST) showed significant elevations from the day of surgery to POD 3 and alanine aminotransferase (ALT) was significantly elevated on POD 1 and POD 3 in the sevo group. Albumin level was significantly lower on POD 2 in the sevo group. Creatinine was significantly higher on POD 3 and POD 30 and estimated glomerular filtration ratio was significantly lower on POD 3 and POD 30 in the sevo group. No patient developed hepatic or renal failures. The results of our study showed better postoperative hepatic and renal function test with desflurane than sevoflurane at equivalent dose of 1 MAC in living donors undergoing right hepatectomy, but further study is required to evaluate clinical importance.

Prediction of the effect of injected ethanol on pulmonary arterial pressure during sclerotherapy of arteriovenous malformations: relationship with dose of ethanol.

PURPOSE: To prospectively evaluate the effect of injected ethanol on pulmonary artery pressure during embolosclerotherapy of arteriovenous malformations (AVMs). MATERIALS AND METHODS: This prospective study was conducted in 16 male and 14 female patients (37 sessions; mean age, 34 years; age range, 17-67 years) with AVMs during a 2-year period. The authors measured pulmonary artery pressure via a pulmonary artery catheter and ethanol levels from the pulmonary and radial arteries simultaneously within 3 minutes after each ethanol injection. The authors analyzed the relationship between pulmonary artery pressure and ethanol levels obtained from pulmonary and radial arteries with respect to both single and cumulative doses of ethanol injected. Retrospectively, patients were divided into two groups-those treated with and those treated without vascular occlusion techniques. RESULTS: The radial arterial ethanol level showed good correlation with the pulmonary arterial ethanol level (r = 0.7). Single dose per injection was statistically related with pulmonary artery pressure (r = 0.5 vs 0.1 and P < .05 vs .29, respectively, in patients treated without and patients treated with vascular occlusion techniques), and the correlation coefficient between cumulative dose and pulmonary artery pressure was 0.2 and 0.3 in respective cases (P < .05 for both). The mean pulmonary artery pressure correlated with pulmonary arterial ethanol level irrespective of the use of vascular occlusion (r = 0.6 for both groups). CONCLUSIONS: Pulmonary artery pressure reflected the pulmonary arterial ethanol level and was positively related to the dose of ethanol. Single dose per injection was predictive of pulmonary artery pressure only in patients treated without vascular occlusion techniques.