The novel application of violacein produced by a marine Duganella strain as a promising agent for controlling Heterosigma akashiwo bloom: Algicidal mechanism, fermentation optimization and agent formulation.

Controlling harmful algal blooms with algicidal bacteria is thought to be an efficient and eco-friendly way but lack of comprehensive studies from theory to practice limited the field application. Here we presented a purple bacterial strain Duganella sp. A3 capable of killing several harmful algae, including Heterosigma akashiwo, a world-wide fish-killing microalga. A bioactivity-guided purification and identification approach revealed the major algicidal compound of A3 as the pigment violacein, which was never reported for its algicidal potential before. Violacein rapidly disrupted cell permeability, caused long-term oxidative stress, but mildly affected algal photosystem, which might explain its highly species-specific activity against unarmored H. akashiwo. To explore the application potential of violacein, a fermentation optimization approach combing single-factor and multi-factor experiments was conducted to increase the violacein yield, which finally reached 0.4199 g/L just using a simple medium formula beneficial for compound purification. Finally, taking advantages of the physical and chemical stabilities, we successfully developed the novel application of violacein as a sustained-releasing and easy-to-preserve algicidal agent using alginate-acacia-gum-chitosan encapsulation, which paved the path for its future application in controlling H. akashiwo bloom.

Association between fresh fruit consumption and the risk of chronic obstructive pulmonary disease-related hospitalization and death in Chinese adults: A prospective cohort study.

BACKGROUND: Existing evidence suggests that fruit consumption is a significant influencing factor for chronic obstructive pulmonary disease (COPD), but this is unclear in the Chinese population. We examined the association of fresh fruit consumption with the risk of COPD-related hospitalization and death in a nationwide, population-based prospective cohort from China. METHODS: Between 2004 and 2008, the China Kadoorie Biobank recruited >0.5 million adults aged 30 to 79 years from ten diverse regions across China. After excluding individuals diagnosed with major chronic diseases and prevalent COPD, the prospective analysis included 421,428 participants. Cox regression was used to calculate the hazard ratios (HRs) for the association between fresh fruit consumption and risk of COPD-related hospitalization and death, with adjustment for established and potential confounders. RESULTS: During a mean follow-up of 10.9 years, 11,292 COPD hospitalization events and deaths were documented, with an overall incidence rate of 2.47/1000 person-years. Participants who consumed fresh fruit daily had a 22% lower risk of COPD-related hospitalization and death compared with non-consumers (HR = 0.78, 95% confidence interval [CI]: 0.71-0.87). The inverse association between fresh fruit consumption and COPD-related hospitalization and death was stronger among non-current smokers and participants with normal body mass index (BMI) (18.5 kg/m 2 ≤ BMI < 24.0 kg/m 2 ); the corresponding HRs for daily fresh fruit consumption were 0.78 (95% CI: 0.68-0.89) and 0.69 (95% CI: 0.59-0.79) compared with their counterparts, respectively. CONCLUSIONS: High-frequency fruit consumption was associated with a lower risk of COPD in Chinese adults. Increasing fruit consumption, together with cigarette cessation and weight control, should be considered in the prevention and management of COPD.

On the Existence of the Exact Solution of Quaternion-Valued Neural Networks Based on a Sequence of Approximate Solutions.

In many practical applications, it is difficult or impossible to obtain the exact solution of the mathematical model due to the limitations of solving methods and the complexity of the neural network itself. A natural problem is given as follows: does the exact solution of quaternion-valued neural networks (QVNNs) exist when successively improved approximate solutions can be obtained? Fortunately, the Hyers-Ulam stability happens to be one of the important means to deal with this problem. In this article, the issue of Hyers-Ulam stability of QVNNs with time-varying delays is addressed. First, inspired by the Hyers-Ulam stability of general functional equations, the concept of the Hyers-Ulam stability of QVNNs is proposed along with the QVNNs model. Then, by utilizing the successive approximation method, both delay-dependent and delay-independent Hyers-Ulam stability criteria are obtained to ensure the Hyers-Ulam stability of the QVNNs considered. Finally, a simulation example is given to verify the effectiveness of the derived results.

A combination of portal vein stent insertion and endovascular iodine-125 seed-strip implantation, followed by transcatheter arterial chemoembolization with sorafenib for treatment of hepatocellular carcinoma-associated portal vein tumor thrombus.

PURPOSE: This study aimed to assess efficacy of portal vein stent (PVS) insertion and endovascular iodine-125 (125I) seed-strip implantation, followed by transcatheter arterial chemoembolization (TACE) with sorafenib (PVS-125I TACE-S) in patients with hepatocellular carcinoma (HCC)-associated type II or type III portal vein tumor thrombus (PVTT). MATERIAL AND METHODS: A retrospective study was performed on 53 consecutive patients with HCC and type II or type III PVTT, from May 2014 to July 2018. Patients were divided into 2 groups, including group A with 28 patients treated with PVS-125I TACE-S, and group B with 25 patients treated with TACE-S. Primary end-point was overall survival (OS), while secondary endpoints were hepatic function and disease control rate (DCR). Albumin-bilirubin (ALBI) score approach was used for evaluating liver function. Cox regression analysis was applied to identify factors associated with treatment outcomes. RESULTS: No pre-operative differences were found in ALBI scores between group A and group B (-2.57 ±0.42 vs. -2.61 ±0.38, p = 0.724), or in these scores at 1 month post-operatively (-2.62 ±0.46 vs. -2.20 ±0.59, p = 0.666). However, these scores were significantly different at 3 (-2.17 ±0.59 vs. -1.69 ±0.48, p = 0.007) and 6 (-2.28 ±1.23 vs. -1.47 ±0.31, p = 0.044) months post-operatively. In addition, group A exhibited higher DCR (71.4% vs. 44.0%, p = 0.043) after 6 months of treatment and extended OS duration (11.4 vs. 7.7 months, p = 0.007). A stratified analysis revealed that OS in patients with type II PVTT did not differ significantly (10.4 vs. 10.7 months, p = 0.689), but OS with type III varied significantly (11.5 vs. 7.5 months, p = 0.002). Multivariate analysis revealed that tumor size > 10 cm (p = 0.002) and multiple tumors (p = 0.022) were independent predictors for poor prognosis, whereas PVS-125I TACE-S was predictor for favorable patient's prognosis (p = 0.040). CONCLUSIONS: PVS-125I TACE-S represents a potentially viable strategy for improving hepatic functionality, DCR, and OS in HCC with type III PVTT compared with TACE-S alone.

The efficacy of the combination of percutaneous transhepatic biliary drainage and 125I stranded seeds for malignant bile duct obstruction treatment.

PURPOSE: To investigate the efficacy of percutaneous transhepatic biliary drainage (PTBD) combined with iodine-125 (125I) stranded seeds for the treatment of malignant bile duct obstruction (MBO). MATERIAL AND METHODS: A retrospective study was performed on 58 consecutive MBO patients. Twenty patients underwent PTBD combined with 125I stranded seeds (group A). Thirty-eight patients underwent percutaneous trans-hepatic biliary drainage (group B). Total bilirubin, direct bilirubin, and indirect bilirubin levels were compared preoperatively, 1-week, 1-month, and 3-months post-operatively. Carbohydrate antigen 19-9 (CA19-9), cancer antigen 125 (CA125), and carcino-embryonic antigen (CEA) levels were compared at preoperative and 3-month post-operative stages. The time free from biliary obstruction and survival times were compared. RESULTS: The differences in total bilirubin, direct bilirubin, and indirect bilirubin levels between the two groups were not significant preoperatively (p = 0.857, p = 0.719, and p = 0.870), and 1-week post-operatively (p = 0.259, p = 0.395, and p = 0.145). However, 1-month (p = 0.012, p = 0.005, and p = 0.049) and 3-months post-operatively (p < 0.001, p = 0.001, and p = 0.001), group A was lower than group B. Differences in CA19-9, CA125, and CEA levels between the two groups were not significant preoperatively (p = 0.229, p = 0.116, and p = 0.273) and 3-months post-operatively (p = 0.159, p = 0.342, and p = 0.306). The median biliary obstruction free time was 7.0 months for group A and 5.0 months for group B (p < 0.001). The median survival time was 9.0 months for group A and 6.0 months for group B (p = 0.001). CONCLUSIONS: PTBD combined with 125I stranded seeds seem to reduce bilirubin levels and prevents biliary obstruction, promoting survival.

New approach to global Mittag-Leffler synchronization problem of fractional-order quaternion-valued BAM neural networks based on a new inequality.

In this paper, a novel kind of neural networks named fractional-order quaternion-valued bidirectional associative memory neural networks (FQVBAMNNs) is formulated. On one hand, applying Hamilton rules in quaternion multiplication which is essentially non-commutative, the system of FQVBAMNNs is separated into eight fractional-order real-valued systems. Meanwhile, the activation functions are considered to be quaternion-valued linear threshold ones which help to reduce the unnecessary computational complexity. On the other hand, based on fractional-order Lyapunov technology, a new fractional-order derivative inequality is established. Mainly by employing the new inequality technique, constructing three novel Lyapunov-Krasovskii functionals (LKFs) and designing simple linear controllers, the global Mittag-Leffler synchronization problems are investigated and the corresponding criteria are acquired for the system of FQVBAMNNs and its special cases such as fractional-order complex-valued BAM neural networks (FCVBAMNNs) and fractional-order real-valued BAM neural networks (FRVBAMNNs), respectively. Finally, two numerical examples are given to show the effectiveness and availability of the proposed results.

Effects of State-Dependent Impulses on Robust Exponential Stability of Quaternion-Valued Neural Networks Under Parametric Uncertainty.

This paper addresses the state-dependent impulsive effects on robust exponential stability of quaternion-valued neural networks (QVNNs) with parametric uncertainties. In view of the noncommutativity of quaternion multiplication, we have to separate the concerned quaternion-valued models into four real-valued parts. Then, several assumptions ensuring every solution of the separated state-dependent impulsive neural networks intersects each of the discontinuous surface exactly once are proposed. In the meantime, by applying the B -equivalent method, the addressed state-dependent impulsive models are reduced to fixed-time ones, and the latter can be regarded as the comparative systems of the former. For the subsequent analysis, we proposed a novel norm inequality of block matrix, which can be utilized to analyze the same stability properties of the separated state-dependent impulsive models and the reduced ones efficaciously. Afterward, several sufficient conditions are well presented to guarantee the robust exponential stability of the origin of the considered models; it is worth mentioning that two cases of addressed models are analyzed concretely, that is, models with exponential stable continuous subsystems and destabilizing impulses, and models with unstable continuous subsystems and stabilizing impulses. In addition, an application case corresponding to the stability problem of models with unstable continuous subsystems and stabilizing impulses for state-dependent impulse control to robust exponential synchronization of QVNNs is considered summarily. Finally, some numerical examples are proffered to illustrate the effectiveness and correctness of the obtained results.

Global Mittag-Leffler stability and synchronization analysis of fractional-order quaternion-valued neural networks with linear threshold neurons.

This paper talks about the stability and synchronization problems of fractional-order quaternion-valued neural networks (FQVNNs) with linear threshold neurons. On account of the non-commutativity of quaternion multiplication resulting from Hamilton rules, the FQVNN models are separated into four real-valued neural network (RVNN) models. Consequently, the dynamic analysis of FQVNNs can be realized by investigating the real-valued ones. Based on the method of M-matrix, the existence and uniqueness of the equilibrium point of the FQVNNs are obtained without detailed proof. Afterwards, several sufficient criteria ensuring the global Mittag-Leffler stability for the unique equilibrium point of the FQVNNs are derived by applying the Lyapunov direct method, the theory of fractional differential equation, the theory of matrix eigenvalue, and some inequality techniques. In the meanwhile, global Mittag-Leffler synchronization for the drive-response models of the addressed FQVNNs are investigated explicitly. Finally, simulation examples are designed to verify the feasibility and availability of the theoretical results.

Algicidal Effects of Prodigiosin on the Harmful Algae Phaeocystis globosa.

Phaeocystis globosa blooms can have negative effects on higher trophic levels in the marine ecosystem and consequently influence human activities. Strain KA22, identified as the bacterium Hahella, was isolated from coastal surface water and used to control P. globosa growth. A methanol extract from the bacterial cells showed strong algicidal activity. After purification, the compound showed a similar structure to prodigiosin when identified with Q-Exactive Orbitrap MS and nuclear magnetic resonance spectra. The compound showed algicidal activity against P. globosa with a 50% Lethal Dose (LD50) of 2.24 µg/mL. The prodigiosin was stable under heat and acid environment, and it could be degraded under alkaline environment and natural light condition. The growth rates of strain KA22 was fast in 2216E medium and the content of prodigiosin in this medium was more than 70 µg/mL after 16 h incubation. The compound showed particularly strong algicidal activity against Prorocentrum donghaiense, P. Globosa, and Heterosigma akashiwo, but having little effect on three other phytoplankton species tested. The results of our research could increase our knowledge on harmful algal bloom control compound and lead to further study on the mechanisms of the lysis effect on harmful algae.

Lysing bloom-causing alga Phaeocystis globosa with microbial algicide: An efficient process that decreases the toxicity of algal exudates.

Algicidal microbes could effectively remove the harmful algae from the waters. In this study, we were concerned with the ecological influence of an algicide extracted from Streptomyces alboflavus RPS, which could completely lyse the Phaeocystis globosa cells within two days. In microcosms, 4 µg/mL of the microbial algicide could efficiently remove P. globosa cells without suppressing other aquatic organisms. Bioluminescent assays confirmed that the toxicity of microbial algicide at this concentration was negligible. Interestingly, the toxicity of P. globosa exudates was also significantly reduced after being treated with the algicide. Further experiments revealed that the microbial algicide could instantly increase the permeability of the plasma membrane and disturb the photosynthetic system, followed by the deformation of organelles, vacuolization and increasing oxidative stress. The pre-incubation of N-acetyl cysteine (NAC) verified that the rapid damages to the plasma membrane and photosynthetic system caused the algal death in the early phase, and the increasing oxidative stress killed the rest. The late accumulation and possible release of CAT also explained the decreasing toxicity of the algal culture. These results indicated that this microbial algicide has great potential in controlling the growth of P. globosa on site.

Comprehensive insights into the response of Alexandrium tamarense to algicidal component secreted by a marine bacterium.

Harmful algal blooms occur throughout the world, threatening human health, and destroying marine ecosystems. Alexandrium tamarense is a globally distributed and notoriously toxic dinoflagellate that is responsible for most paralytic shellfish poisoning incidents. The culture supernatant of the marine algicidal bacterium BS02 showed potent algicidal effects on A. tamarense ATGD98-006. In this study, we investigated the effects of this supernatant on A. tamarense at physiological and biochemical levels to elucidate the mechanism involved in the inhibition of algal growth by the supernatant of the strain BS02. Reactive oxygen species (ROS) levels increased following exposure to the BS02 supernatant, indicating that the algal cells had suffered from oxidative damage. The levels of cellular pigments, including chlorophyll a and carotenoids, were significantly decreased, which indicated that the accumulation of ROS destroyed pigment synthesis. The decline of the maximum photochemical quantum yield (Fv/Fm) and relative electron transport rate (rETR) suggested that the photosynthesis systems of algal cells were attacked by the BS02 supernatant. To eliminate the ROS, the activities of antioxidant enzymes, including superoxide dismutase (SOD) and catalase (CAT), increased significantly within a short period of time. Real-time PCR revealed changes in the transcript abundances of two target photosynthesis-related genes (psbA and psbD) and two target respiration-related genes (cob and cox). The transcription of the respiration-related genes was significantly inhibited by the treatments, which indicated that the respiratory system was disturbed. Our results demonstrate that the BS02 supernatant can affect the photosynthesis process and might block the PS II electron transport chain, leading to the production of excessive ROS. The increased ROS can further destroy membrane integrity and pigments, ultimately inducing algal cell death.

Combination of uniform design with artificial neural network coupling genetic algorithm: an effective way to obtain high yield of biomass and algicidal compound of a novel HABs control actinomycete.

Controlling harmful algae blooms (HABs) using microbial algicides is cheap, efficient and environmental-friendly. However, obtaining high yield of algicidal microbes to meet the need of field test is still a big challenge since qualitative and quantitative analysis of algicidal compounds is difficult. In this study, we developed a protocol to increase the yield of both biomass and algicidal compound present in a novel algicidal actinomycete Streptomyces alboflavus RPS, which kills Phaeocystis globosa. To overcome the problem in algicidal compound quantification, we chose algicidal ratio as the index and used artificial neural network to fit the data, which was appropriate for this nonlinear situation. In this protocol, we firstly determined five main influencing factors through single factor experiments and generated the multifactorial experimental groups with a U15(155) uniform-design-table. Then, we used the traditional quadratic polynomial stepwise regression model and an accurate, fully optimized BP-neural network to simulate the fermentation. Optimized with genetic algorithm and verified using experiments, we successfully increased the algicidal ratio of the fermentation broth by 16.90% and the dry mycelial weight by 69.27%. These results suggested that this newly developed approach is a viable and easy way to optimize the fermentation conditions for algicidal microorganisms.

Streptomyces alboflavus RPS and its novel and high algicidal activity against harmful algal bloom species Phaeocystis globosa.

Phaeocystis globosa blooms have frequently occurred along coastal waters and exerted serious impacts on ecological environments by releasing toxic hemolytic substances, forming nuisance foam, and causing oxygen depletion. An actinomycete strain RPS with high algicidal activity against P. globosa was isolated and identified as Streptomyces alboflavus, based on morphology, physiological and biochemical characteristics, and 16S rDNA sequence analysis. RPS lysed 95% of P. globosa within 48 h by releasing an extracellular active substance into the growth medium. The activity of RPS supernatant was sensitive to temperature at and above 50 °C and insensitive to pH from 3 to 11. The molecular weight of the active substance was between 100 Da and 1000 Da, and approximately 90% of it was extracted by ethyl acetate. It was presumed that the active component efficiently inhibited the movement of P. globosa, caused the flagella to fall off the algae, and finally lysed the algal cells. RPS showed a wide target range against harmful algae. S. alboflavus RPS with high algicidal activity and such novel features of temperature and pH sensitivity, low molecular weight, algicidal process, and target range possesses great potential in the biological control of P. globosa blooms.

Altererythrobacter xiamenensis sp. nov., an algicidal bacterium isolated from red tide seawater.

A Gram-stain-negative, yellow-pigmented, aerobic bacterial strain, designated LY02(T), was isolated from red tide seawater in Xiamen, Fujian Province, China. Growth was observed at temperatures from 4 to 44 °C, at salinities from 0 to 9% and at pH from 6 to 10. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that the isolate was a member of the genus Altererythrobacter, which belongs to the family Erythrobacteraceae. Strain LY02(T) was related most closely to Altererythrobacter marensis MSW-14(T) (97.2% 16S rRNA gene sequence similarity), followed by Altererythrobacter ishigakiensis JPCCMB0017(T) (97.1%), Altererythrobacter epoxidivorans JCS350(T) (97.1%) and Altererythrobacter luteolus SW-109(T) (97.0%). The dominant fatty acids were C(18 : 1)ω7c, C(17 : 1)ω6c and summed feature 3 (comprising C(16 : 1)ω7c and/or C(16 : 1)ω6c). DNA-DNA hybridization showed that strain LY02(T) possessed low DNA-DNA relatedness to A. marensis MSW-14(T), A. ishigakiensis JPCCMB0017(T), A. epoxidivorans JCS350(T) and A. luteolus SW-109(T) (mean ± SD of 33.2 ± 1.3, 32.1 ± 1.0, 26.7 ± 0.7 and 25.2 ± 1.1 %, respectively). The G+C content of the chromosomal DNA was 61.2 mol%. The predominant respiratory quinone was ubiquinone-10 (Q-10). According to its morphology, physiology, fatty acid composition and 16S rRNA gene sequence data, the novel strain most appropriately belongs to the genus Altererythrobacter, but can readily be distinguished from recognized species. The name Altererythrobacter xiamenensis sp. nov. is proposed (type strain LY02(T) = CGMCC 1.12494(T) = KCTC 32398(T) = NBRC 109638(T)).