Pseudomonas aeruginosa detachment from surfaces via a self-made small molecule.

Pseudomonas aeruginosa is a significant threat in both healthcare and industrial biofouling. Surface attachment of P. aeruginosa is particularly problematic as surface association induces virulence and is necessary for the ensuing process of biofilm formation, which hampers antibiotic treatments. Previous efforts have searched for dispersal agents of mature biofilm collectives, but there are no known factors that specifically disperse individual surface-attached P. aeruginosa. In this study, we develop a quantitative single-cell surface-dispersal assay and use it to show that P. aeruginosa itself produces factors that can stimulate its dispersal. Through bioactivity-guided fractionation, mass spectrometry, and nuclear magnetic resonance, we elucidated the structure of one such factor, 2-methyl-4-hydroxyquinoline (MHQ). MHQ is an alkyl quinolone with a previously unknown activity and is synthesized by the PqsABC enzymes. Pure MHQ is sufficient to disperse P. aeruginosa, but the dispersal activity of natural P. aeruginosa conditioned media requires additional factors. Whereas other alkyl quinolones have been shown to act as antibiotics or membrane depolarizers, MHQ lacks these activities and known antibiotics do not induce dispersal. In contrast, we show that MHQ inhibits the activity of Type IV Pili (TFP) and that TFP targeting can explain its dispersal activity. Our work thus identifies single-cell surface dispersal as a new activity of P. aeruginosa-produced small molecules, characterizes MHQ as a promising dispersal agent, and establishes TFP inhibition as a viable mechanism for P. aeruginosa dispersal.

The (PATAN)-CheY-Like Response Regulator PixE Interacts with the Motor ATPase PilB1 to Control Negative Phototaxis in the Cyanobacterium Synechocystis sp. PCC 6803.

The cyanobacterium Synechocystis sp. PCC 6803 can move directionally on a moist surface toward or away from a light source to reach optimal light conditions for its photosynthetic lifestyle. This behavior, called phototaxis, is mediated by type IV pili (T4P), which can pull a single cell into a certain direction. Several photoreceptors and their downstream signal transduction elements are involved in the control of phototaxis. However, the critical steps of local pilus assembly in positive and negative phototaxis remain elusive. One of the photoreceptors controlling negative phototaxis in Synechocystis is the blue-light sensor PixD. PixD forms a complex with the CheY-like response regulator PixE that dissociates upon illumination with blue light. In this study, we investigate the phototactic behavior of pixE deletion and overexpression mutants in response to unidirectional red light with or without additional blue-light irradiation. Furthermore, we show that PixD and PixE partly localize in spots close to the cytoplasmic membrane. Interaction studies of PixE with the motor ATPase PilB1, demonstrated by in vivo colocalization, yeast two-hybrid and coimmunoprecipitation analysis, suggest that the PixD-PixE signal transduction system targets the T4P directly, thereby controlling blue-light-dependent negative phototaxis. An intriguing feature of PixE is its distinctive structure with a PATAN (PatA N-terminus) domain. This domain is found in several other regulators, which are known to control directional phototaxis. As our PilB1 coimmunoprecipitation analysis revealed an enrichment of PATAN domain response regulators in the eluate, we suggest that multiple environmental signals can be integrated via these regulators to control pilus function.

Genetics of the Blue Light-Dependent Signal Cascade That Controls Phototaxis in the Cyanobacterium Synechocystis sp. PCC6803.

The Synechocystis sp. PCC6803 can move on a solid surface in response to light, a phenomenon called phototaxis. Although many of the photoreceptors involved in phototaxis have been identified, the mechanisms that regulate directional motility of Synechocystis are not well understood. Previous studies showed that a mutant lacking the blue light-using flavin (BLUF) photoreceptor PixD exhibits negative phototaxis under conditions where the wild type responds positively. PixD interacts with the pseudo-response regulator-like protein PixE in a light-dependent manner, suggesting that this intermolecular interaction is important for phototaxis regulation, although genetic evidence has been lacking. To gain further insight into phototaxis regulation by PixD-PixE signaling, we constructed the deletion mutants ΔPixE and ΔPixD-ΔPixE, and characterized their phenotypes, which matched those of the wild type (positive phototaxis). Because ΔPixD exhibited negative phototaxis, PixE must function downstream of PixD. Under intense blue light (>100 µmol m-2 s-1; 470 nm) the wild type exhibited negative phototaxis, but ΔPixD-PixE exhibited positive phototaxis toward low-intensity blue light (∼0.8 µmol m-2 s-1; 470 nm). These results suggest that an unknown light-sensing system(s), that is necessary for directional cell movement, can be activated by low-intensity blue light; on the other hand, PixD needs high-intensity blue light to be activated. We also isolated spontaneous mutants that compensated for the pixE deletion. Genome-wide sequencing of the mutants revealed that the uncharacterized gene sll2003 regulates positive and negative phototaxis in response to light intensity.

Paravertebral block catheter breakage by electrocautery during thoracic surgery.

Advantages of thoracic paravertebral analgesia (TPA) include placement of the catheter closer to the surgical field; however, the catheter can become damaged during the operation. We experienced a case of intraoperative TPA catheter breakage that prompted us to perform an experiment to investigate possible causes. A 50-year-old male underwent a thoracoscopic lower lobectomy under general anesthesia with TPA via an intercostal approach. Following surgery, it was discovered that the catheter had become occluded, as well as cut and fused, so we reopened the incision and removed the residual catheter. From that experience, we performed an experiment to examine electrocautery-induced damage in normal (Portex™, Smith's Medical), radiopaque (Perifix SoftTip™, BBraun), and reinforced (Perifix FX™, BBraun) epidural catheters (n = 8 each). Chicken meat was penetrated by each catheter and then cut by electrocautery. In the normal group, breakage occurred in 8 and occlusion in 6 of the catheters, and in the radiopaque group breakage occurred in 8 and occlusion in 7. In contrast, breakage occurred in only 3 and occlusion in none in the reinforced group, with the 5 without breakage remaining connected only by the spring coil. Furthermore, in 7 of the reinforced catheters, electric arc-induced thermal damage was observed at the tip of the catheter. A TPA catheter for thoracic surgery should be inserted via the median approach, or it should be inserted after surgery to avoid catheter damage during surgery.

Scx+/Sox9+ progenitors contribute to the establishment of the junction between cartilage and tendon/ligament.

SRY-box containing gene 9 (Sox9) and scleraxis (Scx) regulate cartilage and tendon formation, respectively. Here we report that murine Scx(+)/Sox9(+) progenitors differentiate into chondrocytes and tenocytes/ligamentocytes to form the junction between cartilage and tendon/ligament. Sox9 lineage tracing in the Scx(+) domain revealed that Scx(+) progenitors can be subdivided into two distinct populations with regard to their Sox9 expression history: Scx(+)/Sox9(+) and Scx(+)/Sox9(-) progenitors. Tenocytes are derived from Scx(+)/Sox9(+) and Scx(+)/Sox9(-) progenitors. The closer the tendon is to the cartilaginous primordium, the more tenocytes arise from Scx(+)/Sox9(+) progenitors. Ligamentocytes as well as the annulus fibrosus cells of the intervertebral discs are descendants of Scx(+)/Sox9(+) progenitors. Conditional inactivation of Sox9 in Scx(+)/Sox9(+) cells causes defective formation in the attachment sites of tendons/ligaments into the cartilage, and in the annulus fibrosus of the intervertebral discs. Thus, the Scx(+)/Sox9(+) progenitor pool is a unique multipotent cell population that gives rise to tenocytes, ligamentocytes and chondrocytes for the establishment of the chondro-tendinous/ligamentous junction.

Rational design of modular polyketide synthases: morphing the aureothin pathway into a luteoreticulin assembly line.

The unusual nitro-substituted polyketides aureothin, neoaureothin (spectinabilin), and luteoreticulin, which are produced by diverse Streptomyces species, point to a joint evolution. Through rational genetic recombination and domain exchanges we have successfully reprogrammed the modular (type I) aur polyketide synthase (PKS) into a synthase that generates luteoreticulin. This is the first rational transformation of a modular PKS to produce a complex polyketide that was initially isolated from a different bacterium. A unique aspect of this synthetic biology approach is that we exclusively used genes from a single biosynthesis gene cluster to design the artificial pathway, an avenue that likely emulates natural evolutionary processes. Furthermore, an unexpected, context-dependent switch in the regiospecificity of a pyrone methyl transferase was observed. We also describe an unprecedented scenario where an AT domain iteratively loads an extender unit onto the cognate ACP and the downstream ACP. This aberrant function is a novel case of non-colinear behavior of PKS domains.

A meta-analysis of the gut microbiome in inflammatory bowel disease patients identifies disease-associated small molecules.

Changes in the gut microbiome have been associated with several human diseases, but the molecular and functional details underlying these associations remain largely unknown. Here, we performed a multi-cohort analysis of small molecule biosynthetic gene clusters (BGCs) in 5,306 metagenomic samples of the gut microbiome from 2,033 Inflammatory Bowel Disease (IBD) patients and 833 matched healthy subjects and identified a group of Clostridia-derived BGCs that are significantly associated with IBD. Using synthetic biology, we discovered and solved the structures of six fatty acid amides as the products of the IBD-enriched BGCs. Using two mouse models of colitis, we show that the discovered small molecules disrupt gut permeability and exacerbate inflammation in chemically and genetically susceptible mice. These findings suggest that microbiome-derived small molecules may play a role in the etiology of IBD and represent a generalizable approach for discovering molecular mediators of microbiome-host interactions in the context of microbiome-associated diseases.

Understanding the effects of a sudden directional shift in somatosensory feedback and increasing task complexity on postural adaptation in individuals with and without chronic ankle instability.

BACKGROUND: Individuals with chronic ankle instability (CAI) present somatosensory dysfunction following an initial ankle sprain. However, little is known about how individuals with CAI adapt to a sudden sensory perturbation of instability with increasing task and environmental constraints to maintain postural stability. METHODS: Forty-four individuals with and without unilateral CAI performed the Adaptation Test to a sudden somatosensory inversion and plantarflexion perturbations (environment) in double-, injured-, and uninjured- limbs. Mean sway energy scores were analyzed using 2 (group) × 2 (somatosensory perturbations) × 3 (task) repeated measures analysis of variance. RESULTS: There were significant interactions between the group, environment, and task (P=.025). The CAI group adapted faster than healthy controls to a sudden somatosensory inversion perturbation in the uninjured- (P=.002) and injured- (P<.001) limbs, as well as a sudden somatosensory plantarflexion perturbation in the double- (P=.033) and uninjured- (P=.035) limbs. The CAI and healthy groups presented slower postural adaptation to a sudden inversion perturbation than a sudden somatosensory plantarflexion perturbation in double-limb (P<.001). Whereas both groups demonstrated faster postural adaptation to a sudden somatosensory inversion perturbation compared to somatosensory plantarflexion perturbation while maintaining posture in the injured- (P<.001) and uninjured- (P<.001) limbs. The CAI and healthy groups adapted faster to a sudden somatosensory inversion perturbation in the injured- (P<.001) and uninjured- (P<.001) limbs than in double-limb, respectively. DISCUSSION: Postural adaptation in individuals with and without CAI depended on environmental (somatosensory perturbations) and task constraints. The CAI group displayed comparable and faster postural adaptation to a sudden somatosensory inversion and plantarflexion in double-, injured-, and uninjured- limbs, which may reflect a centrally mediated alteration in neuromuscular control in CAI.

Generation and characterization of ScxCre transgenic mice.

Scleraxis (Scx) is a basic helix-loop-helix transcription factor that is a marker for the tendon/ligament cell lineage. The ∼11 kb genomic region from the mouse Scx gene locus faithfully recapitulates the endogenous Scx expression pattern in ScxGFP transgenic (Tg) mice. We have established two Tg mouse lines expressing Cre-recombinase (Cre) using this regulatory region (ScxCre-L and ScxCre-H). The specificity and efficiency of Cre recombination in these Tg lines are evaluated by crossing with Rosa-CAG-LSL-tdTomato (Ai14) or ROSA26R (R26R) reporter mice. The recombination in ScxCre-H;Ai14 mice is efficiently achieved in the endogenous Scx expression domains including the branchial arches, the syndetome, and the lateral plate mesoderm. Further analysis of ScxCre-H;Ai14;ScxGFP embryos reveal that expression of the ScxGFP transgene largely overlaps with Cre activity detected by tdTomato at embryonic day 12.5 (E12.5). In ScxCre-L;R26R or ScxCre-H;R26R neonates, Cre activity is detected in tendons, ligaments, intervertebral discs, joints, and cartilage around the chondro-tendinous/ligamentous junction, the prospective enthesis. The present results suggest that ScxCre Tg lines are useful for targeting the gene specifically in the Scx-expressing domains.

Modified proximal thigh kinematics captured with a novel smartphone app in individuals with a history of recurrent ankle sprains and altered dorsiflexion with walking.

BACKGROUND: We examined sagittal-plane thigh angular kinematics in individuals with and without recurrent ankle sprains using a clinical smartphone app called AccWalker. Sagittal-plane ankle kinematics were also compared to ascertain that altered ankle dorsiflexion, which is typically displayed with chronic ankle instability, is also present in individuals with recurrent ankle sprains. METHODS: Participants with (n = 22) and without (n = 22) recurrent ankle sprains were evaluated on average sagittal-plane ankle kinematics during walking and average sagittal-plane thigh angular kinematics during stepping-in-place with AccWalker. FINDINGS: Significant group-by-limb interactions were found for sagittal-plane ankle kinematics (F(1,42) = 63.786, P < .010) during walking and sagittal-plane average thigh angular range-of-motion (F(1,42) = 6.166, P = .017) with AccWalker. Individuals with recurrent ankle sprains displayed more ankle dorsiflexion in affected (P < .001) and unaffected (P = .001) limbs during walking than healthy controls and exhibited more ankle dorsiflexion in their affected-limb compared to their unaffected-limb (P < .001). The average sagittal-plane thigh angular range-of-motion was lower in the unaffected-limb for recurrent ankle sprains compared to their affected-limb (P = .038) and the assigned unaffected-limb of healthy controls (P = .035). INTERPRETATION: Increased dorsiflexion was present in both limbs of the recurrent ankle sprain group with walking. AccWalker does not assess ankle movement, but uniquely identified thigh motion impairments associated with recurrent ankle sprains in their unaffected-limb, potentially identifying central deficits associated with recurrent ankle sprains. This app has clinical implications for assessing potential pathological movement that can be corrected through rehabilitation.

Sensory Reweighting System Differences on Vestibular Feedback with Increased Task Constraints in Individuals with Chronic Ankle Instability Compared to Healthy Controls.

CONTEXT: Chronic ankle instability (CAI) is associated with a less flexibly adaptable sensorimotor system. Thus, individuals with CAI may present an inadequate sensory reweighting system inhibiting the ability to emphasize weight on reliable sensory feedback to control posture. However, how individuals with CAI reweight sensory feedback to maintain postural control in bilateral and unilateral stances has yet to be established. OBJECTIVES: The primary purpose was to examine group differences in how the sensory reweighting system changes to control posture in a simple double-limb stance and a more complex single-limb stance (uninjured-limb, injured-limb) under increased environmental constraints manipulating somatosensory and visual information for individuals with and without CAI. The secondary purpose was to examine the effect of environmental and task constraints on postural control. STUDY DESIGN: Case-control study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: 21 individuals with CAI (26.4±5.7years, 171.2±9.8cm, 76.6±15.17kg) and 21 healthy controls (25.8±5.7years, 169.5±9.5cm, 72.4±15.0kg) participated in the study. MAIN OUTCOME MEASURE(S): Equilibrium10 were examined while completing 6 environmental conditions of the Sensory Organization Test (SOT) during 3 tasks (double-limb and single-limb [uninjured, injured] stances). Sensory reweighting ratios for sensory systems (somatosensory, vision, vestibular) were computed from paired Equilibrium10. RESULTS: Significant 3-factor interactions were found between group, sensory systems, and tasks (P=0.006) and for groups, task, and environment (P=0.007). The CAI group failed to downweight vestibular feedback compared to healthy controls while maintaining posture in the injured-limb (P=0.030). The CAI group displayed better postural stability than healthy controls while standing with absent vision, fixed surroundings, and a moving platform in the injured-limb (P=0.032). CONCLUSIONS: The CAI group relied on vestibular feedback while maintaining better postural stability than healthy controls in the injured-limb. Group differences in postural control depended on both environmental (absent vision, moving platform) and task (injured-limb) constraints.

Interchenar retrotransfer of aureothin intermediates in an iterative polyketide synthase module.

The course of the enigmatic iterative use of a polyketide synthase module was deduced from targeted domain inactivation in the aureothin assembly line. Mutational analyses revealed that the N-terminus of AurA is not involved in the iteration process, ruling out an ACP-ACP shuttle. Furthermore, an AurA(KS°, ACP°)-AurA(AT(0)) heterodimer proved to be nonfunctional, whereas aureothin production was restored in a ΔaurA mutant complemented with AurA(KS°)-AurA(ACP°). This finding supports a model according to which the ACP-bound polyketide intermediate is transferred back to the KS domain on the opposite PKS strand.

Olfactory coding in five moth species from two families.

The aim of the present study was to determine what impact phylogeny and life history might have on the coding of odours in the brain. Using three species of hawk moths (Sphingidae) and two species of owlet moths (Noctuidae), we visualized neural activity patterns in the antennal lobe, the first olfactory neuropil in insects, evoked by a set of ecologically relevant plant volatiles. Our results suggest that even between the two phylogenetically distant moth families, basic olfactory coding features are similar. But we also found different coding strategies in the moths' antennal lobe; namely, more specific patterns for chemically similar odorants in the two noctuid species than in the three sphingid species tested. This difference demonstrates the impact of the phylogenetic distance between species from different families despite some parallel life history traits found in both families. Furthermore, pronounced differences in larval and adult diet among the sphingids did not translate into differences in the olfactory code; instead, the three species had almost identical coding patterns.

Detection of the full-length transcript variant for neurokinin-1 receptor in human whole blood associated with enhanced reinforcement of clot by substance-P.

We have recently reported that a neurotransmitter for pain, substance-P (SP), promotes platelet-dependent clot formation through neurokinin-1 receptors (NK1Rs), in which leukocytes appear to be involved (J Thromb Thrombolysis 2009;27:280-6). Two naturally occurring splice isoforms of NK1R with different signal transduction potency, namely the full-length and the truncated NK1Rs are identified. It is known that human leukocytes express truncated NK1Rs, while in vivo expression of the full-length NK1R has not yet been fully clarified. Modulatory effects of alternative splicing for NK1Rs on clot formation also remain to be evaluated. Expression of the transcript variant mRNA for NK1Rs in human whole blood (n = 20) was evaluated by real-time reverse transcription polymerase chain reaction (RT-PCR). A 15 min time series of the strength of clot, formed after reloading of calcium in citrated whole blood with or without SP (10 nM) and a NK1R antagonist Spantide (1 µM), was measured by using oscillating-probe viscoelastometry. The full-length transcript variant was detected in 5 samples among 20. SP significantly increased the clot strength while Spantide suppressed the SP-derived change. The extent of modulation by SP/NK1R pathway in a subgroup with expression of the full-length transcript variant was three times as potent as those in another subgroup without expression. We conclude that expression of the full-length transcript variant for NK1R can be detected in human whole blood and that such expression is associated with the enhanced reinforcement of clot by SP. Further study is required to nominate this mRNA as a biomarker for prothrombotic risks in painful conditions such as perioperative period.

A femto-injection technique for dynamic analysis of protein function in living embryonic stem cells.

The potential of a femto-injection technique for use in analyzing protein dynamics in embryonic stem (ES) cells was investigated. First, we showed that fluorescent proteins could be injected in a quantitative fashion into individual mouse ES cells. Second, we demonstrated that the technique could identify functional differences between proteins by analyzing the effect of a nuclear localization signal on the behavior of glutathione S-transferase conjugated to green fluorescent protein. The analysis showed a clear difference in the distribution of the protein when the nuclear localization signal was present. Our results confirm that the non-destructive, quantitative and time controllable aspects of the technique provide considerable advantages for the analysis of protein behavior in living ES cells. To the best of our knowledge, this is the first report of the successful introduction of proteins into living ES cells by an injection technique.

[Postoperative pain management by intravenous patient-controlled analgesia in patients undergoing upper abdominal gastrointestinal surgery].

BACKGROUND: We conducted a retrospective study to evaluate the effectiveness of intravenous patient-controlled analgesia (IVPCA) in the early postoperative period after upper abdominal gastrointestinal surgery. We also evaluated the postoperative effects of intraoperative analgesic dosage in patients after this surgery. METHODS: A total of 59 adult patients classified as ASA 1-3 were allocated to one of two groups: Group A, 23 patients who requested IVPCA more than 50 times, and Group B, 36 patients with fewer than 50 requests. IVPCA was induced using morphine 1 mg x ml(-1) without a base dose. The bolus dose was 1 ml and the lock-out time was 5 min. RESULTS: There was no significant difference between the two groups in the total intraoperative remifentanil dosage/body weight/surgical duration, predicted effect-site concentration of fentanyl during extubation, and utilization of flurbiprofen. The doses of morphine were significantly higher, and the visual analogue scale scores for pain at rest and during movement tended to be lower in group A than in group B. CONCLUSIONS: The results of this study suggest that the effects of intraoperative analgesics may not be significant. Patients who had received the above mentioned anesthetic regimen intraoperatively also required full postoperative analgesia as well.

An Extension of Reversible Image Enhancement Processing for Saturation and Brightness Contrast.

This paper proposes a reversible image processing method for color images that can independently improve saturation and enhance brightness contrast. Image processing techniques have been popularly used to obtain desired images. The existing techniques generally do not consider reversibility. Recently, many reversible image processing methods have been widely researched. Most of the previous studies have investigated reversible contrast enhancement for grayscale images based on data hiding techniques. When these techniques are simply applied to color images, hue distortion occurs. Several efficient methods have been studied for color images, but they could not guarantee complete reversibility. We previously proposed a new method that reversibly controls not only the brightness contrast, but also saturation. However, this method cannot fully control them independently. To tackle this issue, we extend our previous work without losing its advantages. The proposed method uses the HSV cone model, while our previous method uses the HSV cylinder model. The experimental results demonstrate that our method flexibly controls saturation and brightness contrast reversibly and independently.

In vivo localization and oligomerization of PixD and PixE for controlling phototaxis in the cyanobacterium Synechocystis sp. PCC 6803.

Phototaxis is a phenomenon where cyanobacteria move toward a light source. Previous studies have shown that the blue-light-using-flavin (BLUF)-type photoreceptor PixD and the response regulator-like protein PixE control the phototaxis in the cyanobacterium Synechocystis sp. PCC 6803. The pixD-null mutant moves away from light, whereas WT, pixE mutant, and pixD pixE double mutant move toward the light. This indicates that PixE functions downstream of PixD and influences the direction of movement. However, it is still unclear how the light signal received by PixD is transmitted to PixE, and then subsequently transmitted to the type IV pili motor mechanism. Here, we investigated intracellular localization and oligomerization of PixD and PixE to elucidate mechanisms of phototaxis regulation. Blue-native PAGE analysis, coupled with western blotting, indicated that most PixD exist as a dimer in soluble fractions, whereas PixE localized in ~250 kDa and ~450 kDa protein complexes in membrane fractions. When blue-native PAGE was performed after illuminating the membrane fractions with blue light, PixE levels in the ~250 kDa and ~450 kDa complexes were reduced and increased, respectively. These results suggest that PixE, localized in the ~450 kDa complex, controls activity of the motor ATPase PilB1 to regulate pilus motility.

Emulating evolutionary processes to morph aureothin-type modular polyketide synthases and associated oxygenases.

Polyketides produced by modular type I polyketide synthases (PKSs) play eminent roles in the development of medicines. Yet, the production of structural analogs by genetic engineering poses a major challenge. We report an evolution-guided morphing of modular PKSs inspired by recombination processes that lead to structural diversity in nature. By deletion and insertion of PKS modules we interconvert the assembly lines for related antibiotic and antifungal agents, aureothin (aur) and neoaureothin (nor) (aka spectinabilin), in both directions. Mutational and functional analyses of the polyketide-tailoring cytochrome P450 monooxygenases, and PKS phylogenies give contradictory clues on potential evolutionary scenarios (generalist-to-specialist enzyme evolution vs. most parsimonious ancestor). The KS-AT linker proves to be well suited as fusion site for both excision and insertion of modules, which supports a model for alternative module boundaries in some PKS systems. This study teaches important lessons on the evolution of PKSs, which may guide future engineering approaches.