Which Nebulizer Position Should Be Avoided? An Extended Study of Aerosol Delivery and Ventilator Performance during Noninvasive Positive Pressure Ventilation.

BACKGROUND: Research on the effect of nebulizer location on aerosol delivery during noninvasive ventilation has reached inconsistent conclusions. OBJECTIVE: To investigate the effects of nebulizer position on aerosol delivery efficiency and ventilator performance during noninvasive ventilation. METHODS: The Active Servo Lung 5000 respiratory simulation system (ASL5000) was used to simulate a COPD patient. The noninvasive ventilator was set to the spontaneous breathing mode. Six nebulizer positions, 2 exhalation valve types (single-arch exhalation port and whisper swivel), 4 combinations of inspiratory and expiratory pressure, and 2 respiratory rates were used. RESULTS: Significant differences between nebulizer positions existed in aerosol delivery (p < 0.05). Aerosol delivery efficiency was lower for nebulizer locations on either side of the exhalation valve and next to the ventilator outlet. When the nebulizer was located between the exhalation valve and the simulated lung, increased inspiratory pressure increased and increased expiratory pressure decreased delivery efficiency (both p < 0.05). When the nebulization device was located between the exhalation valve and the ventilator, no obvious trend was observed. Compared to baseline, nebulization lowered the air leakage volume displayed on the ventilator. There were no differences in ventilator performance between different nebulizer positions. CONCLUSIONS: The closer the nebulizer was to the exhalation valves or ventilator, the lower the aerosol delivery efficiency. Nebulizer position had little clinically significant effect on ventilator performance.

Antioxidative responses in zebrafish liver exposed to sublethal doses Aphanizomenon flos-aquae DC-1 aphantoxins.

Aphanizomenon flos-aquae secretes paralytic shellfish poisons (PSPs), termed aphantoxins, and endangers environmental and human health via eutrophication of water worldwide. Although the molecular mechanism of neuronal PSP toxicity has been well studied, several issues remain unresolved, notably the in vivo hepatic antioxidative responses to this neurotoxin. Aphantoxins extracted from a natural isolate of A. flos-aquae DC-1 were resolved by high performance liquid chromatography. The primary components were gonyautoxins 1 and 5 and neosaxitoxin. Zebrafish (Danio rerio) were treated intraperitoneally with either 5.3 or 7.61 (low and high doses, respectively) µg saxitoxin (STX) equivalents (eq)/kg of A. flos-aquae DC-1 aphantoxins. Antioxidative responses in zebrafish liver were examined at different timepoints 1-24h post-exposure. Aphantoxin administration significantly enhanced hepatic malondialdehyde (MDA) content 1-12h post-exposure, indicative of oxidative stress and lipid peroxidation. By contrast, levels of reduced glutathione (GSH) in zebrafish liver declined significantly after 3-24h exposure, suggesting that GSH participates in MDA metabolism. A significant upregulation of the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) was observed, suggesting that aphantoxins induce lipid peroxidation in zebrafish liver and are likely to be hepatotoxic. Hepatic levels of MDA and GSH, and of the three enzymes (SOD, CAT, and GPx), therefore provide potential biomarkers for studying environmental exposure to aphantoxins/PSPs from cyanobacterial blooms.

Moderate coffee or tea consumption decreased the risk of cognitive disorders: an updated dose-response meta-analysis.

CONTEXT: Although several epidemiological studies have examined the association between coffee or tea intake and the risk of cognitive disorders, the results to date are inconsistent. OBJECTIVE: An updated systematic review and dose-response meta-analysis was conducted to confirm the association between coffee, tea, and caffeine consumption and the risk of cognitive disorders. DATA SOURCES: PubMed, Embase, and Web of Science were searched from inception to January 2022 for relevant studies, including dementia, Alzheimer disease (AD), and cognitive impairment or decline. DATA EXTRACTION: Two reviewers independently performed data extraction and assessed the study quality. DATA ANALYSIS: Restricted cubic splines were used to conduct the dose-response meta-analysis for coffee and tea intake. RESULTS: Twenty-two prospective studies and 11 case-control studies involving 389 505 participants were eligible for this meta-analysis. Coffee and tea consumption was linked to a lower risk of cognitive disorders, with an overall relative risk (RR) of 0.73 (95% CI: 0.60-0.86) and 0.68 (95% CI: 0.56-0.80), respectively. The subgroup analysis revealed that ethnicity, sex, and outcomes had significant effects on this association. Protection was stronger for men than that for women in both coffee and tea consumption. A nonlinear relationship was found between coffee consumption and AD risk, and the strength of protection peaked at approximately 2.5 cups/day (RR: 0.74; 95% CI: 0.59-0.93). A linear relationship was found between tea consumption and cognitive disorders, and the risk decreased by 11% for every 1-cup/day increment. CONCLUSION: This meta-analysis demonstrated that the consumption of 2.5 cups coffee/day minimizes the risk of AD, and 1 cup/day of tea intake leads to an 11% reduction in cognitive deficits. Effective interventions involving coffee and tea intake might prevent the occurrence of dementia.

Hemilophiacardiocarpa (Brassicaceae), a new species from Yunnan, southwest China.

Hemilophiacardiocarpa (Brassicaceae), the sixth species of the Chinese endemic genus Hemilophia, is described and illustrated. This plant is found in the Jiaozishan Mountains in Dongchuan District, northern Yunnan, southwest China. Morphologically, it shows close relationships with H.rockii and H.pulchella, but differs from it in the leaf shape and size, inflorescence, flower size, shape of fruit and length of its pedicel. An updated key to the taxa of Hemilophia is provided.

The widespread capability of methylphosphonate utilization in filamentous cyanobacteria and its ecological significance.

Aquatic ecosystems comprise almost half of total global methane emissions. Recent evidence indicates that a few strains of cyanobacteria, the predominant primary producers in bodies of water, can produce methane under oxic conditions with methylphosphonate serving as substrate. In this work, we have screened the published 2 568 cyanobacterial genomes for genetic elements encoding phosphonate-metabolizing enzymes. We show that phosphonate degradation (phn) gene clusters are widely distributed in filamentous cyanobacteria, including several bloom-forming genera. Algal growth experiments revealed that methylphosphonate is an alternative phosphorous source for four of five tested strains carrying phn clusters, and can sustain cellular metabolic homeostasis of strains under phosphorus stress. Liberation of methane by cyanobacteria in the presence of methylphosphonate occurred mostly during the light period of a 12 h/12 h diurnal cycle and was suppressed in the presence of orthophosphate, features that are consistent with observations in natural aquatic systems under oxic conditions. The results presented here demonstrate a genetic basis for ubiquitous methane emission via cyanobacterial methylphosphonate mineralization, while contributing to the phosphorus redox cycle.

Comparative genomics reveals insights into cyanobacterial evolution and habitat adaptation.

Cyanobacteria are photosynthetic prokaryotes that inhabit diverse aquatic and terrestrial environments. However, the evolutionary mechanisms involved in the cyanobacterial habitat adaptation remain poorly understood. Here, based on phylogenetic and comparative genomic analyses of 650 cyanobacterial genomes, we investigated the genetic basis of cyanobacterial habitat adaptation (marine, freshwater, and terrestrial). We show: (1) the expansion of gene families is a common strategy whereby terrestrial cyanobacteria cope with fluctuating environments, whereas the genomes of many marine strains have undergone contraction to adapt to nutrient-poor conditions. (2) Hundreds of genes are strongly associated with specific habitats. Genes that are differentially abundant in genomes of marine, freshwater, and terrestrial cyanobacteria were found to be involved in light sensing and absorption, chemotaxis, nutrient transporters, responses to osmotic stress, etc., indicating the importance of these genes in the survival and adaptation of organisms in specific habitats. (3) A substantial fraction of genes that facilitate the adaptation of Cyanobacteria to specific habitats are contributed by horizontal gene transfer, and such genetic exchanges are more frequent in terrestrial cyanobacteria. Collectively, our results further our understandings of the adaptations of Cyanobacteria to different environments, highlighting the importance of ecological constraints imposed by the environment in shaping the evolution of Cyanobacteria.

Responses of pro- and anti-inflammatory cytokines in zebrafish liver exposed to sublethal doses of Aphanizomenon flosaquae DC-1 aphantoxins.

Blooms of the dominant cyanobacterium Aphanizomenon flosaquae are frequently encountered in natural waters, and their secretion of neurotoxic paralytic shellfish toxins called aphantoxins threatens environmental safety and human health worldwide. The liver is the primary detoxification organ in animals, and its pro- and anti-inflammatory responses are important functions in the detoxification of toxins. Therefore, we investigated the response of these inflammatory factors to aphantoxins in the liver of zebrafish (Danio rerio). A. flosaquae DC-1 was sampled during blooms in Dianchi Lake, China and cultured, and the toxin was extracted and analyzed using high performance liquid chromatography. The primary constituents were gonyautoxins 1 (34.04%) and 5 (21.28%) and neosaxitoxin (12.77%). Zebrafish were injected intraperitoneally with 5.3 µg (low dose) or 7.61 µg (high dose) of saxitoxin equivalents [equivalents (eq.)]/kg body weight of A. flosaquae DC-1 aphantoxins. Hyperemia, the hepatosomatic index (HSI), and physiological and molecular responses of pro- and anti-inflammatory cytokines in the zebrafish liver were investigated at different time points 1-24 h post-exposure. Aphantoxins significantly enhanced hepatic hyperemia and altered the HSI 3-24 h post-exposure, suggesting that inflammation caused morphological changes. Subsequent investigations using the enzyme-linked immunosorbent assay showed that the pro-inflammatory cytokines tumor necrosis factor-α, interleukin-1ß (IL-1ß), IL-6, and IL-8 and anti-inflammatory cytokines IL-10 and transforming growth factor ß were higher in the liver of zebrafish exposed to aphantoxins, which indicated physiological inflammatory responses. Further analysis by real-time fluorescence quantitative polymerase chain reaction demonstrated upregulated mRNA expression of these cytokines, suggesting molecular inflammatory responses in the zebrafish liver. These changes showed dose- and time-dependent patterns. These results indicated that aphantoxins induced hyperemia and altered the HSI, and subsequently increased the levels of proinflammatory cytokines TNF-α, IL-1ß, IL-6 and IL-8 to induce physiological inflammatory responses. These changes activated the anti-inflammatory cytokines IL-10 and TGF-ß to suppress inflammatory damage. The induced changes were the result of upregulated mRNA expression of these inflammatory cytokines caused by aphantoxins. Aphantoxins resulted in hepatic immunotoxicity and response by inducing pro-inflammatory cytokines. Zebrafish liver in turn suppressed the inflammatory damage by upregulating the activities of anti-inflammatory cytokines. In the future, these pro- and anti-inflammatory cytokines in the zebrafish liver may be prove to be useful biomarkers of aphantoxins and blooms in nature.

Laparoscopic Heller-Dor operation for patients with achalasia.

BACKGROUND: Laparoscopic Heller cardiomyotomy and Dor fundoplication is the surgical procedure of choice for esophageal achalasia. The aim of this study was to investigate the clinical outcome of laparoscopic Heller-Dor procedure in our initial series of 25 patients with achalasia. METHODS: Between October 2003 and January 2006, a total of 25 patients with achalasia underwent laparoscopic Heller-Dor operation. Among them, 9 were male and 16 were female with an average age of (41.5 +/- 5.1) years (21-66). All the patients received upper gastrointestinal series (barium swallow), esophagogastroscopy, esophageal manometry to exclude esophageal carcinoma and to confirm the diagnosis, and 21 patients also had 24-hour ambulatory pH studies. All the patients were operated by laparoscopic modified Heller's myotomy with Dor fundoplication. In addition, 2 of them had combined laparoscopic cholecystectomy + excision of hepatic hemangioma and laparoscopic cholecystectomy, respectively. RESULTS: The average operating time was (110.6 +/- 12.9) minutes (range, 60-180), operative blood loss averaged (18.6 +/- 7.1) ml (5-50), the median time to oral feeding was (1.6 +/- 0.4) days (1-4) and the median hospital stay was (12.6 +/- 1.2) days (10-20). There was no conversion to open surgery. Intraoperative mucosal perforation was encountered in six patients and was repaired in all of them by laparoscopic suture. All the patients had an uneventful recovery without postoperative complication. After a median follow-up of (10.6 +/- 7.2) months (1-27), 24 patients were asymptomatic and 1 had mild postoperative dysphagia. CONCLUSIONS: Laparoscopic Heller-Dor operation had the advantages of reduced compromise of the cardiopulmonary function, with less disruption of the supporting structures (phrenoesophageal membrane) of the antireflux mechanism, requiring simpler general anesthesia and providing excellent exposure permitting an easy fundoplication, less pain and reduced morbidity, shorter hospitalization and faster convalescence.

Respiratory toxicity of cyanobacterial aphantoxins from Aphanizomenon flos-aquae DC-1 in the zebrafish gill.

Aphantoxins from Aphanizomenon flos-aquae are frequently identified in eutrophic waterbodies worldwide. These toxins severely endanger environmental safety and human health due to the production of paralytic shellfish poisons (PSPs). Although the molecular mechanisms of aphantoxin neurotoxicity have been studied, many questions remain to be resolved such as in vivo alterations in branchial histology and neurotransmitter inactivation induced by these neurotoxins. Aphantoxins extracted from a naturally isolated strain of A. flos-aquae DC-1 were determined by high performance liquid chromatography. The basic components of the isolated aphantoxins identified were gonyautoxin 1 (GTX1), gonyautoxin 5 (GTX5), and neosaxitoxin (neoSTX), which comprised 34.04, 21.28, and 12.77% of the total, respectively. Zebrafish (Danio rerio) was administrated 5.3 or 7.61mg STX equivalents (eq)/kg (low and high doses, respectively) of the A. flos-aquae DC-1 aphantoxins by intraperitoneal injection. Histological alterations and changes in neurotransmitter inactivation in the gills of zebrafish were investigated for 24h following exposure. Aphantoxin exposure significantly increased the activities of gill alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and resulted in histological alterations in the gills during the first 12h of exposure, indicating the induction of functional and structural damage. Gill acetylcholinesterase (AChE) and monoamine oxidase (MAO) activities were inhibited significantly, suggesting an alteration of neurotransmitter inactivation in zebrafish gills. The observed alterations in gill structure and function followed a time- and dose-dependent pattern. The results demonstrate that aphantoxins or PSPs lead to structural damage and altered function in the gills of zebrafish, including changes in histological structure and increases in the activities of AST and ALT. The inhibition of the activities of AChE and MAO suggest that aphantoxins or PSPs could induce respiratory toxicity in the zebrafish gill. Furthermore, these parameters may be used as bioindicators for investigating aphantoxin exposure and cyanobacterial blooms in nature.

Morphological alterations and acetylcholinesterase and monoamine oxidase inhibition in liver of zebrafish exposed to Aphanizomenon flos-aquae DC-1 aphantoxins.

Aphanizomenon flos-aquae is a cyanobacterium that produces neurotoxins or paralytic shellfish poisons (PSPs) called aphantoxins, which present threats to environmental safety and human health via eutrophication of water bodies worldwide. Although the molecular mechanisms of this neurotoxin have been studied, many questions remain unsolved, including those relating to in vivo hepatic neurotransmitter inactivation, physiological detoxification and histological and ultrastructural alterations. Aphantoxins extracted from the natural strain of A. flos-aquae DC-1 were analyzed by high-performance liquid chromatography. The main components were gonyautoxins 1 and 5 (GTX1, GTX5) and neosaxitoxin (neoSTX), which comprised 34.04%, 21.28%, and 12.77% respectively. Zebrafish (Danio rerio) were exposed intraperitoneally to 5.3 or 7.61 µg STX equivalents (eq)/kg (low and high doses, respectively) of A. flos-aquae DC-1 aphantoxins. Morphological alterations and changes in neurotransmitter conduction functions of acetylcholinesterase (AChE) and monoamine oxidase (MAO) in zebrafish liver were detected at different time points 1-24h post-exposure. Aphantoxin significantly enhanced hepatic alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and histological and ultrastructural damage in zebrafish liver at 3-12 h post-exposure. Toxin exposure increased the reactive oxygen species content and reduced total antioxidative capacity in zebrafish liver, suggesting oxidative stress. AChE and MAO activities were significantly inhibited, suggesting neurotransmitter inactivation/conduction function abnormalities in zebrafish liver. All alterations were dose- and time-dependent. Overall, the results indicate that aphantoxins/PSPs induce oxidative stress through inhibition of AChE and MAO activities, leading to neurotoxicity in zebrafish liver. The above parameters may be useful as bioindicators for investigating aphantoxins/PSPs and cyanobacterial blooms in nature.

[Development and succession of artificial biological soil crusts and water holding characteristics of topsoil].

In order to understand the improving effects of cyanobacterial inoculation on water retention of topsoil in desert regions, this work focused on the development and succession of biological soil crusts and water holding characteristics of topsoil after cyanobacterial inoculation in Qubqi Desert. The results showed that after the artificial inoculation of desert cyanobacteria, algal crusts were quickly formed, and in some microenvironments direct succession of the algal crusts to moss crusts occurred after 2-3 years. With the development and succession of biological soil crusts, the topsoil biomass, polysaccharides content, crust thickness and porosity increased, while the soil bulk density decreased. At the same time, with crust development and succession, the topsoil texture became finer and the percents of fine soil particles including silt and clay contents increased, while the percents of coarse soil particles (sand content) decreased proportionately. In addition, it was found that with crust development and succession, the water holding capacity and water content of topsoil showed an increasing trend, namely: moss crust > algal crusts > shifting sand. The water content (or water holding capacity) in algal and moss crusts were 1.1-1.3 and 1.8-2.2 times of those in shifting sand, respectively. Correlation analysis showed that the water holding capacity and water content of topsoil were positively correlated with the crust biomass, polysaccharides content, thickness, bulk density, silt and clay content; while negatively correlated with the porosity and sand content. Furthermore, stepwise regression analysis showed that the main factor affecting water content was the clay content, while that affecting water holding capacity was the porosity.

[Development and succession of biological soil crusts and the changes of microbial biomasses].

Biological soil crusts (BSCs) play important ecological roles in vegetation and ecological restoration in desert regions, and different crust developmental and successional stages have different ecological functions. In this experiment, the BSCs in Shapotou region (at southeast edge of Tengger Desert) were investigated to study crust development and succession through field investigation, microscopic observation combined with quantitative analysis of microbial biomasses. The results showed that BSCs in this region generally developed and succeeded from algal crusts, lichen crusts to moss crusts. With the development and succession of BSCs, crust photosynthetic biomass gradually increased, while microalgal biomass showed a first increasing and then decreasing trend. Among the crust algae (cyanobacteia), Microcoleus vaginatus, as the first dominant species, occupied the most algal biomass and reached a maximum of 0.33 mm3 x g(-1) crusts in algal crusts; while Scytonema javanicum and Nostoc sp. have their maximal biomasses in the later lichen crusts. In addition, it was found that the heterotrophic microbial biomass began to increase in algal crusts, and then decreased in lichen crusts; followed by another increase and the increase achieved the maximum at last in moss crusts. Through the correlation analysis, it was found that bacterial biomass significantly positively correlated with crust organic carbon and Na+ content, while fungal biomass positively correlated with K+ and Na+ content (P < 0.05). In conclusion, this study investigated the developmental and successional patterns of BSCs in Shapotou region, and discussed the effects of crust development and succession on several microbial biomasses from the point of view of environmental adaptation and functional requirement, which may be helpful for us to understand crust development and succession, and provide theoretical and practical significances for crust maintenance and management in ecological restoration of desertification regions.

Lipid peroxidation and antioxidant responses in zebrafish brain induced by Aphanizomenon flos-aquae DC-1 aphantoxins.

Aphanizomenon flos-aquae is a cyanobacterium that is frequently encountered in eutrophic waters worldwide. It is source of neurotoxins known as aphantoxins or paralytic shellfish poisons (PSPs), which present a major threat to the environment and human health. The molecular mechanism of PSP action is known, however the in vivo effects of this neurotoxin on oxidative stress, lipid peroxidation and the antioxidant defense responses in zebrafish brain remain to be understood. Aphantoxins purified from a natural isolate of A. flos-aquae DC-1 were analyzed using high performance liquid chromatography. The major components of the toxins were gonyautoxins 1 and 5 (GTX1 and GTX5, 34.04% and 21.28%, respectively) and neosaxitoxin (neoSTX, 12.77%). Zebrafish (Danio rerio) were injected intraperitoneally with 7.73 µg/kg (low dose) and 11.13 µg/kg (high dose) of A. flos-aquae DC-1 aphantoxins. Oxidative stress, lipid peroxidation and antioxidant defense responses in the zebrafish brain were investigated at various timepoints at 1-24h post-exposure. Aphantoxin exposure was associated with significantly increased (>1-2 times) reactive oxygen species (ROS) and malondialdehyde (MDA) in zebrafish brain compared with the controls at 1-12h postexposure, suggestive of oxidative stress and lipid peroxidation. In contrast, reduced glutathione (GSH) levels in the zebrafish brain exposed to high or low doses of aphantoxins decreased by 44.88% and 41.33%, respectively, after 1-12h compared with the controls, suggesting that GSH participated in detoxification to ROS and MDA. Further analysis showed a significant increase in the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) compared with the controls, suggesting elimination of oxidative stress by the antioxidant response in zebrafish brain. All these changes were dose and time dependent. These results suggested that aphantoxins or PSPs increased ROS and MDA and decreased GSH in zebrafish brain, and these changes induced oxidative stress. The increased activity of SOD, CAT and GPx demonstrated that these antioxidant enzymes could play important roles in eliminating excess ROS and MDA. These results also suggest that MDA, ROS, GSH and these three antioxidant enzymes in the brain of zebrafish may act as bioindicators for investigating A. flos-aquae DC-1 aphantoxins or PSPs and algal blooms in nature.

Zebrafish locomotor capacity and brain acetylcholinesterase activity is altered by Aphanizomenon flos-aquae DC-1 aphantoxins.

Aphanizomenon flos-aquae (A. flos-aquae) is a source of neurotoxins known as aphantoxins or paralytic shellfish poisons (PSPs) that present a major threat to the environment and to human health. Generally, altered neurological function is reflected in behavior. Although the molecular mechanism of action of PSPs is well known, its neurobehavioral effects on adult zebrafish and its relationship with altered neurological functions are poorly understood. Aphantoxins purified from a natural isolate of A. flos-aquae DC-1 were analyzed by HPLC. The major analogs found in the toxins were the gonyautoxins 1 and 5 (GTX1 and GTX5; 34.04% and 21.28%, respectively) and the neosaxitoxin (neoSTX, 12.77%). Zebrafish (Danio rerio) were intraperitoneally injected with 5.3 and 7.61 µg STXeq/kg (low and high dose, respectively) of A. flos-aquae DC-1 aphantoxins. The swimming activity was investigated by observation combined with video at 6 timepoints from 1 to 24 h post-exposure. Both aphantoxin doses were associated with delayed touch responses, reduced head-tail locomotory abilities, inflexible turning of head, and a tailward-shifted center of gravity. The normal S-pattern (or undulating) locomotor trajectory was replaced by a mechanical motor pattern of swinging the head after wagging the tail. Finally, these fish principally distributed at the top and/or bottom water of the aquarium, and showed a clear polarized distribution pattern at 12 h post-exposure. Further analysis of neurological function demonstrated that both aphantoxin doses inhibited brain acetylcholinesterase activity. All these changes were dose- and time-dependent. These results demonstrate that aphantoxins can alter locomotor capacity, touch responses and distribution patterns by damaging the cholinergic system of zebrafish, and suggest that zebrafish locomotor behavior and acetylcholinesterase can be used as indicators for investigating aphantoxins and blooms in nature.

[Stem profile model and variable-exponent of Larix gmelinii plantation].

A series of previous taper equations with variable parameters were compared in this study. The model with better fitting results (smaller residual sum of squares and higher correlation index) for Larix gmelinii taper was selected in terms of model fitting statistics (residual sum of squares and correlation index), and five indices for describing the taper were proposed, according to the meanings of variable parameters in the model. Among the taper equations compared, the equation provided by Lee et al. had better fitting effect, and could be used to describe the tapers of L. gmelinii plantation. The five indices including taper rate of root, influence point, ranges of parabolic and paraconic, minimum of variable parameters, and relative height at minimum of variable parameters could be taken as the methods and tools for comparing the tapers. Only moderate stand density (487 plant x hm(-2)) provided good quality of larch stem form, compared to both high (870 plant x hm(-2)) and low (275 plant x hm(-2)) stand density providing poor quality.