Current trends and advances of Quorum sensing inhibitors and their biotechnological applications

Serious setbacks were witnessed in shrimp farming, the food industry, and the ship industry during the past three decades primarily due to bacterial pathogens that coordinate by quorum sensing (QS). The influence of bacterial pathogens utilizing QS. The impact of QS cell communication on public health is extremely disastrous in terms of spread, spectrum, apart from their economic impact. The overuse of antibiotics has increased drastically to battle bacterial infections, including tons of antibiotics are distributed in the biosphere. Due to the indiscriminate use of antibiotics, multiple antibiotic-resistant strains have emerged, as the antibiotic resistance genes are being transferred to bacteria of terrestrial animals, humans, and pathogens. The increased public awareness of the negative drawbacks caused by over-exposure to antibiotics, also the emergence of multiple antibiotic resistant pathogenic stains led to the search for alternatives and unique solutions. One such unconventional, promising method is the interruption of bacterial cell to cell communication, which is currently termed QS inhibition. Now-a-days, QS inhibition is the potential objective for antimicrobial chemotherapy. This review summarizes the regulatory factors that attenuate the QS activities of deadly pathogens and discusses their distinctive characteristics. Improving awareness of the natural roles of regulatory elements might be useful in unveiling inhibitor applications to understand how QS is inhibited in pathogenic bacteria by different QS inhibitors.

Comparison Between the SFTS-QS Kit and the PowerChek SFTSV Real-time PCR Kit for the Detection of Severe Fever With Thrombocytopenia Syndrome Virus

The recent increase in severe fever with thrombocytopenia syndrome (SFTS) cases has led to the development of the SFTS-QS kit (MiCoBioMed, Seongnam, Korea) for detecting the SFTS virus (SFTSV, now renamed Huaiyangshan banyangvirus). SFTS-QS is a qualitative real-time reverse transcription PCR assay based on lab-on-a-chip technology. We evaluated the performance of the SFTS-QS kit and compared it with that of the PowerChek SFTSV Real-time PCR kit (PowerChek; Kogene Biotech, Seoul, Korea). A total of 117 serum samples were simultaneously assayed using the SFTS-QS and PowerChek kits. Sanger sequencing targeting the S and M segments of SFTSV was performed as the reference method. The total turnaround time of the two kits was compared. The SFTS-QS results agreed with those of PowerChek with a kappa value of 0.92. The diagnostic sensitivity and specificity of the SFTS-QS kit were both 100% (14/14 and 103/103, respectively), whereas those of the PowerChek kit were 100% (14/14) and 98.1% (101/103), respectively. The results of SFTS-QS and PowerChek were comparable; however, the SFTS-QS kit required a shorter total turnaround time. The SFTS-QS kit produced accurate and fast results and thus could serve as a useful tool for detecting SFTSV.

Biofilm production by clinical isolates of Pseudomonas aeruginosa and structural changes in LasR protein of isolates non biofilm-producing

ABSTRACT Introduction: Biofilm production is an important mechanism for the survival of Pseudomonas aeruginosa and its relationship with antimicrobial resistance represents a challenge for patient therapeutics. P. aeruginosa is an opportunistic pathogen frequently associated to nosocomial infections, especially in imunocompromised hosts. Objectives: Analyze the phenotypic biofilm production in P. aeruginosa isolates, describe clonal profiles, and analyze quorum sensing (QS) genes and the occurrence of mutations in the LasR protein of non-biofilm producing isolates. Methods: Isolates were tested for biofilm production by measuring cells adherence to the microtiter plates. Clonal profile analysis was carried out through ERIC-PCR, QS genes were by specific PCR. Results: The results showed that 77.5% of the isolates were considered biofilm producers. The results of genotyping showed 38 distinct genetic profiles. As for the occurrence of the genes, 100% of the isolates presented the lasR, rhlI and rhlR genes, and 97.5%, presented the lasI gene. In this study nine isolates were not biofilm producers. However, all presented the QS genes. Amplicons related to genes were sequenced in three of the nine non-biofilm-producing isolates (all presenting different genetic similarity profile) and aligned to the sequences of those genes in P. aeruginosa strain PAO1 (standard biofilm-producing strain). Alignment analysis showed an insertion of three nucleotides (T, C and G) causing the addition of an amino acid valine in the sequence of the LasR protein, in position 53. Conclusion: The modeling of the resulting LasR protein showed a conformational change in its structure, suggesting that this might be the reason why these isolates are unable to produce biofilm.

Quorum Sensing Regulation of Biofilm Formation by Periodontal Pathogens

Quorum sensing (QS) is a cell density-dependent communication mechanism between bacteria through small signaling molecules. When the number of QS signaling molecules reaches a threshold, they are transported back into the cells or recognized by membrane-bound receptors, triggering gene expression which affects various phenotypes including bioluminescence, virulence, adhesion, and biofilm formation. These phenotypes are beneficial for bacterial survival in harsh environments. This review summarizes the application of QS inhibitors for control of biofilm formation and virulence expression of periodontal pathogens.

AidE encodes an N-acyl homoserine lactonase in Acinetobacter / 生物工程学报

Quorum sensing (QS) is a cell-cell communication mechanism that allows bacterial populations to coordinate gene expression in response to cell density. N-acylhomoserine lactones (AHL) are used as quorum-sensing signal molecules by many Gram negative bacteria. Acinetobacter sp. 77, an AHL-degrading bacterium, was isolated in our previous work. The gene aidE for AHL inactivation was cloned in this study by screening a genomic DNA library. The deduced protein AidE is 268 amino acids in length and shares a high identity (95%) with the beta-lactamase family protein in Acinetobacter gyllenbergii CIP110306, but low identities with known AHL-degrading enzymes. HPLC analysis of the AidE-degraded C6-HSL products revealed that AidE functioned as an AHL lactonase. Sequences alignment suggested that the aidE gene is not conserved in Acinetobacter species, flanking sequences of aidE and their arrangement are specific in Acinetobacter sp. 77 genome, and some IS insertion sequences were found downstream of the aidE gene. These evidences indicated that the aidE gene might be foreign DNA taken up via horizontal gene transferring or had changed its relative location due to the genome rear-arrangement. Expression of the aidE gene in Pectobacterium carotovorum subsp. carotovorum Z3-3 significantly reduced its AHL production as well as the pathogenicity on host plants, indicating that AidE was able to effectively quench quorum sensing-dependent functions in bacteria. In conclusion, aidE is a newfound AHL-lactonase with a potential for suppression of bacterial infections.

Comparison of the QIAGEN artus HBV QS-RGQ Assay With the Roche COBAS AmpliPrep/COBAS TaqMan HBV Assay for Quantifying Viral DNA in Sera of Chronic Hepatitis B Patients

BACKGROUND: Hepatitis B virus DNA quantification is essential for managing chronic hepatitis B (CHB). We compared the performance of artus HBV QS-RGQ (QIAGEN GmbH, Germany) and CAP/CTM v2.0 HBV assays (Roche Molecular Diagnostics, USA) in CHB patients. METHODS: A comparative evaluation between two assays was performed with 508 clinical serum samples. Precision, linearity, and the limit of detection (LOD) of QS-RGQ assay was evaluated by using the WHO standard 97/750 and clinical samples. RESULTS: Detection rates and viral loads as determined QS-RGQ assay were significantly lower than those from the CAP/CTM v2.0 assay (52.8% vs 60.6%; 3.55±1.77 IU/mL vs 4.18±1.89 IU/mL, P<0.0001). The kappa coefficient between qualitative results was 0.79 (95% confidence interval, 0.74 to 0.85). Bland-Altman plot found a mean difference of (QS-RGQ − CAP/CTM v2.0)=−0.63 log₁₀ IU/mL (95% limit of agreement, −1.48 to 0.22). Repeatability and total imprecision (% CV) of the QS-RGQ assay were 1.0% and 1.1% at 2,000 IU/mL, and 0.7% and 1.4% at 20,000 IU/mL, respectively. Linearity of this assay ranged from 31.6 to 1.0±10⁷ IU/mL, and the LOD was 2.95 IU/mL. CONCLUSIONS: The artus HBV QS-RGQ assay showed good performance but significantly decreased detection rate and viral load compared with CAP/CTM v2.0 assays. This assay recommends using plasma; however, we used stored serum because of the retrospective study design. Usually HBV DNA quantification is performed in plasma or serum, but sample type and clinical relevance of quantitative values should be considered when determining the clinical application of this reagent.

Evaluation of echocardiographic markers in dogs with patent ductus arteriosus after ductal closure

This study evaluated several known echocardiographic markers related to the assessment of severity in dogs with patent ductus arteriosus (PDA) after the closure of ductus arteriosus (DA). Forty-two dogs with patent ductus arteriosus were enrolled in this study. Evaluated echocardiographic markers were left atrial to aortic root ratio, left ventricular end-diastolic dimension to aortic root ratio, indexed left ventricular end-diastolic and end-systolic dimensions, end-diastolic and end systolic volume index, pulmonic flow to systemic flow (Qp/Qs) ratio, velocities of pulmonary regurgitant and systolic jets, pulmonary flow profiles and the presence of mitral regurgitation. Those markers were evaluated before, 1 day, and 30 days after the closure of DA. Statistically significant changes in some echocardiographic markers (i.e., Qp/Qs) were observed. Although several studies in human and dogs have evaluated the clinical outcome of PDA occlusion using several echocardiographic markers, this study has firstly evaluated all echocardiographic markers known to be useful for assessing the clinical outcome of PDA occlusion in human, and has demonstrated that those markers including the Qp/Qs and pulmonary flow profiles were useful in evaluating of clinical outcome of PDA in dogs and the reduction of LA and LV preload after ductal closure could dramatically reduce after successful ductal occlusion of PDA in dogs.

QS-21 enhances the early antibody response to oil adjuvant foot-and-mouth disease vaccine in cattle

PURPOSE: One of the most important tools against foot-and-mouth disease, a highly contagious and variable viral disease of cloven-hoofed animals, is vaccination. However, the effectiveness of foot-and-mouth disease vaccines on slowing the spread of the disease is questionable. In contrast, high potency vaccines providing early protection may solve issues with the spread of the disease, escaping mutants, and persistency. To increase the potency of the vaccine, additives such as saponin and aluminium hydroxide are used. However, the use of saponin with an oil adjuvant is not common and is sometimes linked to toxicity. QS-21, which is less toxic than Quil A, has been presented as an alternative for use with saponin. In this study, the addition of QS-21 to a commercially available foot-and-mouth disease water-in-oil-in-water emulsion vaccine was evaluated in cattle. MATERIALS AND METHODS: After vaccination, serum samples were collected periodically over 3 months. Sera of the QS-21 and normal oil vaccine groups were compared via serum virus neutralization antibody titre and liquid phase blocking enzyme-linked immunosorbent assay antibody titre. RESULTS: The results showed that there was a significant early antibody increase in the QS-21 group. CONCLUSION: Strong early virus neutralizing antibody response will be useful for emergency or ring vaccinations against foot-and-mouth disease in target animals.

Antibacterial, anti-swarming and anti-biofilm formation activities of Chamaemelum nobile against Pseudomonas aeruginosa

Chamomile ( Chamaemelum nobile ) is widely used throughout the world, and has anti-inflammatory, deodorant, bacteriostatic, antimicrobial, carminative, sedative, antiseptic, anti-catarrhal, and spasmolytic properties. Because of the increasing incidence of drug-resistant bacteria, the development of natural antibacterial sources such as medical herbs for the treatment of infectious diseases is necessary. Extracts from different plant parts such as the leaves, flowers, fruit, and bark of Combretum albiflorum, Laurus nobilis , and Sonchus oleraceus were found to possess anti-quorum sensing (QS) activities. In this study, we evaluated the effect of C. nobile against Pseudomonas aeruginosa biofilm formation

Hypopigmentation Induced by Frequent Low-Fluence, Large-Spot-Size QS Nd:YAG Laser Treatments

The Q-switched 1064-nm neodymium-doped yttrium aluminum garnet (QS 1064-nm Nd:YAG) laser is increasingly used for nonablative skin rejuvenation or "laser toning" for melasma. Multiple and frequent low-fluence, large-spot-size treatments are used to achieve laser toning, and these treatments are associated with the development of macular hypopigmentation as a complication. We present a case series of three patients who developed guttate hypomelanotic macules on the face after receiving laser toning treatment with QS 1064-nm Nd:YAG.

Screening of certain medicinal plants from India for their anti-quorum sensing activity.

Discovery of quorum sensing (QS) system to coordinate virulence and biofilm formation in bacterial pathogens has triggered search for safe, stable and non-toxic anti-QS compounds from natural products. Ethanolic extracts of 24 Indian medicinal plants were tested by agar well and disc diffusion assay for anti-QS activity using Chromobacterium violaceum (CV12472 and CVO26) reporter strains. AHL from C. violaceum CV31532 was isolated and partially purified for its use in CVO26 based bioassay. Effect on swarming-motility of Pseudomonas aeruginosa (PAO1) was also recorded at sub-MIC concentrations of extracts. Of the 24 medicinal plants screened Hemidesmus indicus (L.) Schult (root), Holarrhena antidysenterica (Roth)A.DC. (bark), Mangifera indica L. (seed) Punica granatum L. (pericarp) and Psoralea corylifolia L. (seed) demonstrated varying level of inhibition of violacein production in the reporter strains. Moreover, a significant reduction in swarms was recorded over control. The inhibition of violacein production and swarming motility may be due to direct or indirect interference on QS by active constituents or the interactive effect of different phytocompounds present in the extracts. These plant extracts may be selected for activity guided fractionation to identify and characterize the active principle

Early Results of MIS-QS Total Knee Arthroplasty: A Comparison with Conventional Procedure for the Same Patient / 대한정형외과학회잡지

PURPOSE: This study assessed the early clinical and radiological results of Minimally Invasive Surgery- Quadriceps sparing total knee arthroplasty (MIS-QS TKA), and compared these results with those of conventional TKA. MATERIALS AND METHODS: Between August 2004 and March 2005, 17 patients with bilateral TKA on their one side using a regular procedure and the other using the MIS-QS technique were evaluated and compared. The clinical assessment was performed by measuring the range of motion, Knee Society Score, and a radiological evaluation by standing anteroposterior, supine lateral, and Merchant view preoperatively, 2 weeks, 6 weeks, 3 months and 1 year after surgery. Statistical analysis was performed using a paired t-test. RESULTS: The average range of knee motion was slightly larger in the MIS-QS group at all periodsbut there was no statistical difference between the two groups. The Knee Society Score was similar at the 3 month and 1 year periods. The alignment of the implants was satisfactory in both groups and postoperative patellar alignment checked in the Merchant view was better in the MIS-QS group at all periods. CONCLUSION: There were no differences in the clinical aspects at 1 year period between the two groups. However, the MIS-QS group showed better patellar alignment than the conventional group for up to 1 year.

Construction of Pseudomonas sp. M18 pqsR Mutant and Its Regulation on Plt Biosynthesis / 微生物学通报

Pseudomonas sp. M18 is one of plant growth-promoting rhizobacteria capable of producing two kinds of anti-fungal agents: phenazine-1-carboxilic acid (PCA) and pyoluteorin (Plt). The pqsR gene, which encodes a LysR family member PqsR, was amplified from chromosomal genome of strain M18. Using the homologous recombination technique, a chromosomal pqsR inactivated mutant strain M18PRG was constructed in Pseudomonas sp. M18. To study the effect of pqsR gene on Plt biosynthesis, the dynamic curves of Plt production by strains M18 and M18PRG was measured in KMB media. As a result, Plt production of the pqsR mutant was three to four folds higher than that of its parent strain M18. The Plt production was restored to the wild-type level when strain M18PRG was complemented with pqsR gene in trans. The regulation of pqsR gene on Plt production was further confirmed by the pltA′-′lacZ translational fusion analysis. These results indicate that pqsR gene negatively controls the Plt biosynthesis. Additionally, by analyzing the growth curves of wild type strain M18 and pqsR mutant, wecan readily find that PqsR has a negative influence on cell growth. It was also shown that the production of red pigments in strain M18 required the expression of pqsR gene. In conclusion, the data presented in this study clearly demonstrate that PqsR acts as a global regulator involved in many physiological activities in Pseudomonas sp. M18.

Measurement of Shunt Amount Using Radionuclide Angiocardiography: Accuracy According to Level of Shunt and Associated Lesion / 핵의학분자영상

PURPOSE: Determination of pulmonary to systemic blood flow ratio (QP/QS) is important for the management of patients with left-to-right shunt. This study was performed to assess the agreement of Qp/Qs ratio using the radionuclide method and oxymetry, to investigate the factors influencing the agreement, and to know how interchangeable the results of each technique. MATERIALS AND METHODS: We compared the Qp/Qs measured by single-pass radionuclide angiocardiography and oxymetry during catheterization in 207 patients who underwent both studies. In radionuclide method, Qp/Qs was calculated from the pulmonary time-activity curves using a gamma variate fit. The correlation and Bland-Altman analysis were performed according to the levels of shunt and associated lesions. RESULTS: The mean Qp/Qs was 1.83+/10.50 by radionuclide, and 1.74+/10.51 by oxymetry. The overall correlation coefficient was 0.86(p<0.001), and Bland-Altman range of agreement encompassing 4SD was 1.05. For atrial septal defect, ventricular septal defect, patent ductus arteriosus, tricuspid and mitral insufficiency, the correlation coefficient was 0.78, 0.90, 0.84, 0.63 and 0.44, and Bland-Altman range was 1.52, 0.74, 0.96, 1.57, and 1.50, respectively. CONCLUSION: There is good agreement but wide variance between the Qp/Qs ratios by radionuclide method and oxymetry. Associated atrioventricular valvar insufficiency decreases the correlation coefficient and widens the variance. Wide overall variance suggests that Qp/Qs measurements by two techniques should not be used interchangeably.

Hemifacial Rejuvenation Effect after Treatment of Nevus of Ota with the Q-switched Alexandrite Laser

Q-switched(QS) Lasers have been successfully used to treat nevus of Ota with a few complications. A 51 year old woman had nevus of Ota affecting the left half of her face from birth. During childhood and adolescence, her nevus enlarged and has remained stable since her late teens. She was treated with Q- switched Alexandrite Laser (fluences: 5.5J/cm2, spot size: 3mm, repetition rate: 10Hz). After 7 sessions(interval 6 weeks), complete clearance was achieved. She complained that the treated side of her face looked much younger than the other side. Alexandrite Laser therapy and post- treatment therapies might be considered to cause this problem. First, she applied 0.025% retinoid and 4% hydroquinone ointment on her treated area every night. Second, laser treatment for intradermal pigmented lesion tightened dermal collagens. In cases of middle aged women with dermal pigmented lesions (nevus of Ota), collagen tightness of dermal layer is considered to cause rejuvenation effect. In order to balance the two sides of her face, we made her apply the same post-treatment therapies on the normal side. After 18months, the effect of rejuvenation of the treated area still lasted and the normal side also improved. This case implies that skin care on the entire face pre- and post-treatment is important in a laser therapy for nevus of Ota. Especially when it comes to middle aged women, rejuvenation therapies are recommended.

Systolic and diastolic time intervals during prolonged exercise of a constant intensity / 体力科学

The purpose of this study was to elucidate the changes in systolic and diastolic time intervals which accrue along with increase of HR during a prolonged exercise.<BR>Fifteen male collegiate distance runners performed bicycle ergometer exercise of 70% maximal oxygen intake for 60 minutes. Electrocardiogram, phonocardiogram, pulse wave using ear densitogram and its derivative were recorded throughout the exercise, and then HR, STI, DT (diastolic time) and QS<SUB>2</SUB>/DT were caluculated from the tracings.<BR>The results obtained are as follows:<BR>1. At the initial phase of the exercise, DT decreased markedly to result in rapid increase of QS<SUB>2</SUB>/DT. When HR was between 130-150 beats/min, however, the rate of decrease of QS<SUB>2</SUB> was greater than that of DT, so QS<SUB>2</SUB>/DT showed a tendency to decrease. When HR was more than 150, QS<SUB>2</SUB> reached a plateau but DT still continued to decrease, and QS<SUB>2</SUB>/DT turned to increase again.<BR>2. LVET decreased slowly throughout the exercise, whereas PEP decreased rapidly within initial two minutes and kept a steady state thereafter. The change in QS<SUB>2</SUB> after two minutes of exercise seemed to depend on LVET.<BR>3. LVETi and QS<SUB>2</SUB>i showed a similar change as that in QS<SUB>2</SUB>/DT but the change in QS<SUB>2</SUB>i was less obvious than that in LVETi.<BR>4. PEN and PEP/LVET decreased rapidly in the initial two minutes, thereafter they continued to increase more slowly with increase of HR until the end of exercise.<BR>Conclusively, HR continued to increase monotonously during prolonged exercise of a constant intensity, while systolic and diastolic time intervals varied the directions and patterns of their changes during the exercise.