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1.
Environ Sci Pollut Res Int ; 31(11): 16473-16484, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38321280

ABSTRACT

g-C3N4/ZnxCd(1-x)S composites were synthesized by a simple hydrothermal method. The composites were characterized by X-ray diffraction, UV-vis diffuse reflectance spectroscopy, infrared spectroscopy, and electron micro-projective microscopy. According to the performance of ZnxCd(1-x)S for the photocatalytic degradation of norfloxacin under visible light in water, the best stoichiometric number of x was 0.5. The best photolytic norfloxacin degradation rate of g-C3N4/ZnxCd(1-x)S composites was 89.8%, which was obtained when the dosage ratio of g-C3N4 to ZnxCd(1-x)S was 1:1. The experiment was conducted to investigate the effect of pH on the catalyst to obtain the optimal NORF degradation environment pH in the range of 7 ± 0.3; by simulating the anions that may be contained in the actual environmental water, the results showed that the catalyst has a certain effect on the degradation of NORF when the water contains NO3-, Cl- and HCO3-. In addition, this study also obtained that the main active substances produced by the catalyst during degradation were electron-hole pairs by adding different trapping agents in the NORF removal experiments; and the catalyst was able to achieve a degradation rate of 86.1% after four cycles of the experiments, which proved that it had good stability.


Subject(s)
Anti-Bacterial Agents , Norfloxacin , Anti-Bacterial Agents/chemistry , Cadmium , Photolysis , Light , Zinc
2.
Am J Infect Control ; 52(7): 827-833, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38281685

ABSTRACT

BACKGROUND: Patients with neurocritically illness are an under-recognized population at high risk of sepsis. We aimed to investigate the prevalence, early predictors, and outcomes of sepsis in neuro-ICU. METHODS: Daily and accumulative incidences of sepsis in neuro-ICU were explored. Demographics, medical history, baseline disease severity scores, and baseline biomarkers regarding inflammation, immunology, organ function, and nutritional status were collected and analyzed as potential predictors of sepsis. Logistic regression analyses were used to determine the independent predictors, and a nomogram was used to estimate the individual probability of sepsis in neuro-ICU. RESULTS: 153 patients were included in this study. Fifty-nine (38.6%) patients developed sepsis, and 21 (14%) patients developed septic shock. More than 86% of the septic cases occurred within the first week. Sequential organ failure assessment score ((relative risk) RR 1.334, P = .026), history of diabetes (RR 2.346, P = .049), and transferrin (RR 0.128, P = .042) on admission are independent predictors of sepsis. Septic patients had significantly higher mortality (P = .011), higher medical cost (P = .028), and a lower rate of functional independence (P = .010), compared to patients without sepsis. CONCLUSIONS: Sepsis afflicted more than one-third of neurocritically-ill patients and occurred mostly in the first week of admission. History of diabetes, serum transferrin, and sequential organ failure assessment score on admission were early predictors. Sepsis led to significantly worse outcomes and higher medical costs.


Subject(s)
Sepsis , Humans , Male , Sepsis/epidemiology , Sepsis/mortality , Sepsis/complications , Female , Middle Aged , Prospective Studies , Prevalence , Aged , Adult , Critical Illness , Risk Factors , Intensive Care Units , Nervous System Diseases/epidemiology , Nervous System Diseases/etiology , Prognosis
3.
Neurol Sci ; 45(6): 2719-2728, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38150131

ABSTRACT

OBJECTIVES: Patients with severe stroke are at high risk of developing acute respiratory distress syndrome (ARDS), but this severe complication was often under-diagnosed and rarely explored in stroke patients. We aimed to investigate the prevalence, early predictors, and outcomes of ARDS in severe stroke. METHODS: This prospective study included consecutive patients admitted to neurological intensive care unit (neuro-ICU) with severe stroke, including acute ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage. The incidence of ARDS was examined, and baseline characteristics and severity scores on admission were investigated as potential early predictors for ARDS. The in-hospital mortality, length of neuro-ICU stay, the total cost in neuro-ICU, and neurological functions at 90 days were explored. RESULTS: Of 140 patients included, 35 (25.0%) developed ARDS. Over 90% of ARDS cases occurred within 1 week of admission. Procalcitonin (OR 1.310 95% CI 1.005-1.707, P = 0.046) and PaO2/FiO2 on admission (OR 0.986, 95% CI 0.979-0.993, P < 0.001) were independently associated with ARDS, and high brain natriuretic peptide (OR 0.994, 95% CI 0.989-0.998, P = 0.003) was a red flag biomarker warning that the respiratory symptoms may be caused by cardiac failure rather than ARDS. ARDS patients had longer stays and higher expenses in neuro-ICU. Among patients with ARDS, 25 (62.5%) were moderate or severe ARDS. All the patients with moderate to severe ARDS had an unfavorable outcome at 90 days. CONCLUSIONS: ARDS is common in patients with severe stroke, with most cases occurring in the first week of admission. Procalcitonin and PaO2/FiO2 on admission are early predictors of ARDS. ARDS worsens both short-term and long-term outcomes. The conflict in respiratory support strategies between ARDS and severe stroke needs to be further studied.


Subject(s)
Respiratory Distress Syndrome , Stroke , Humans , Respiratory Distress Syndrome/epidemiology , Respiratory Distress Syndrome/complications , Male , Female , Aged , Prospective Studies , Prevalence , Middle Aged , Stroke/epidemiology , Stroke/complications , Intensive Care Units/statistics & numerical data , Severity of Illness Index , Hospital Mortality , Aged, 80 and over , Length of Stay/statistics & numerical data
4.
Epilepsia ; 64(6): 1594-1604, 2023 06.
Article in English | MEDLINE | ID: mdl-36892496

ABSTRACT

OBJECTIVE: This study was undertaken to characterize the blood-brain barrier (BBB) dysfunction in patients with new onset refractory status epilepticus (NORSE) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). METHODS: This study included three groups of adult participants: patients with NORSE, encephalitis patients without status epilepticus (SE), and healthy subjects. These participants were retrospectively included from a prospective DCE-MRI database of neurocritically ill patients and healthy subjects. The BBB permeability (Ktrans) in the hippocampus, basal ganglia, thalamus, claustrum, periventricular white matter, and cerebellum were measured and compared between these three groups. RESULTS: A total of seven patients with NORSE, 14 encephalitis patients without SE, and nine healthy subjects were included in this study. Among seven patients with NORSE, only one had a definite etiology (autoimmune encephalitis), and the rest were cryptogenic. Etiology of encephalitis patients without SE included viral (n = 2), bacterial (n = 8), tuberculous (n = 1), cryptococcal (n = 1), and cryptic (n = 2) encephalitis. Of these 14 encephalitis patients without SE, three patients had seizures. Compared to healthy controls, NORSE patients had significantly increased Ktrans values in the hippocampus (.73 vs. .02 × 10-3 /min, p = .001) and basal ganglia (.61 vs. .003 × 10-3 /min, p = .007) and a trend in the thalamus (.24 vs. .08 × 10-3 /min, p = .017). Compared to encephalitis patients without SE, NORSE patients had significantly increased Ktrans values in the thalamus (.24 vs. .01 × 10-3 /min, p = .002) and basal ganglia (.61 vs. .004 × 10-3 /min, p = .013). SIGNIFICANCE: This exploratory study demonstrates that BBBs of NORSE patients were impaired diffusely, and BBB dysfunction in the basal ganglia and thalamus plays an important role in the pathophysiology of NORSE.


Subject(s)
Encephalitis , Status Epilepticus , Adult , Humans , Blood-Brain Barrier/diagnostic imaging , Retrospective Studies , Prospective Studies , Status Epilepticus/diagnostic imaging , Status Epilepticus/etiology , Encephalitis/complications , Magnetic Resonance Imaging
5.
Front Immunol ; 14: 1115031, 2023.
Article in English | MEDLINE | ID: mdl-36860868

ABSTRACT

Background: Inflammatory mechanisms play important roles in intracerebral hemorrhage (ICH) and have been linked to the development of stroke-associated pneumonia (SAP). The neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), platelet-to-lymphocyte ratio (PLR) and systemic inflammation response index (SIRI) are inflammatory indexes that influence systemic inflammatory responses after stroke. In this study, we aimed to compare the predictive value of the NLR, SII, SIRI and PLR for SAP in patients with ICH to determine their application potential in the early identification of the severity of pneumonia. Methods: Patients with ICH in four hospitals were prospectively enrolled. SAP was defined according to the modified Centers for Disease Control and Prevention criteria. Data on the NLR, SII, SIRI and PLR were collected at admission, and the correlation between these factors and the clinical pulmonary infection score (CPIS) was assessed through Spearman's analysis. Results: A total of 320 patients were enrolled in this study, among whom 126 (39.4%) developed SAP. The results of the receiver operating characteristic (ROC) analysis revealed that the NLR had the best predictive value for SAP (AUC: 0.748, 95% CI: 0.695-0.801), and this outcome remained significant after adjusting for other confounders in multivariable analysis (RR=1.090, 95% CI: 1.029-1.155). Among the four indexes, Spearman's analysis showed that the NLR was the most highly correlated with the CPIS (r=0.537, 95% CI: 0.395-0.654). The NLR could effectively predict ICU admission (AUC: 0.732, 95% CI: 0.671-0.786), and this finding remained significant in the multivariable analysis (RR=1.049, 95% CI: 1.009-1.089, P=0.036). Nomograms were created to predict the probability of SAP occurrence and ICU admission. Furthermore, the NLR could predict a good outcome at discharge (AUC: 0.761, 95% CI: 0.707-0.8147). Conclusions: Among the four indexes, the NLR was the best predictor for SAP occurrence and a poor outcome at discharge in ICH patients. It can therefore be used for the early identification of severe SAP and to predict ICU admission.


Subject(s)
Pneumonia , Stroke , United States , Humans , Neutrophils , Pneumonia/diagnosis , Inflammation , Cerebral Hemorrhage/diagnosis , Lymphocytes
6.
Brain Inj ; 37(6): 461-467, 2023 05 12.
Article in English | MEDLINE | ID: mdl-36803124

ABSTRACT

BACKGROUND: The guidelines of brain death determination vary across countries. Our aim was to compare diagnostic procedures of brain death determination in adults among five countries. METHOD: Consecutive comatose patients who received brain death determination from June 2018 to June 2020 were included. The technical specifications, completion rates and positive rates of brain death determination according to criteria of different countries were compared. The accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of each ancillary test for the identification of brain death diagnosed according to different criteria were investigated. RESULTS: One hundred and ninety nine patients were included in this study. One hundred and thirty one (65.8%) patients were diagnosed with brain death according to French criteria, 132 (66.3%) according to Chinese criteria, and 135 (67.7%) according to criteria of USA, UK and Germany. The sensitivity and PPV of electroencephalogram (92.2% - 92.3%) and somatosensory evoked potential (95.5% - 98.5%) were higher than transcranial Doppler (84.3% - 86.0%). CONCLUSIONS: The criteria of brain death in China and France are comparatively stricter than in USA, UK and Germany. The discrepancy in brain death determination between clinical assessments and additional confirmation of ancillary tests is small.


Subject(s)
Brain Death , Brain , Humans , Adult , Brain Death/diagnosis , Brain/diagnostic imaging , Coma/diagnosis , Predictive Value of Tests , Ultrasonography, Doppler, Transcranial
7.
Mol Biol Rep ; 49(7): 6303-6311, 2022 Jul.
Article in English | MEDLINE | ID: mdl-35474057

ABSTRACT

BACKGROUND: Oxidative stress and neurocyte apoptosis are crucial pathophysiological process in early brain injury (EBI) after subarachnoid hemorrhage (SAH). Geniposide (GNP) has been reported to exert neuroprotective effects by reducing oxidative injury and neurocyte apoptosis. However, the effect of GNP has not been clarified in EBI after SAH. The study was performed to evaluate the neuroprotective effects and mechanisms of GNP in EBI after SAH. METHODS AND RESULTS: A total of 60 male Wistar rats were randomly divided into five groups. The prechiasmatic cistern SAH model was used in this study. SAH grade was evaluated using a grading system. Neurological function was evaluated using the Garcia scores. Brain edema was measured by the wet-dry method. Blood-brain barrier (BBB) permeability was measured by the extravasation of Evans Blue (EB). The neurocyte apoptosis was observed using TUNEL assay. The levels of malondialdehyde (MDA) and superoxide dismutase (SOD), as well as the expressions of nuclear factor erythroid 2-related factor 2 (Nrf2), hemeoxygenase-1 (HO-1), glutathione S-transferase (GST) and quinone oxidoreductase-1 (NQO-1) were performed. The results showed that GNP reduced brain edema, attenuated BBB permeability, inhibited neurocyte apoptosis and improved neurological function. Moreover, GNP also decreased the levels of ROS and MDA, elevated Nrf2 expression in the temporal cortex and up-regulated the expression of NQO-1, HO-1 and GST after SAH. CONCLUSIONS: GNP could ameliorate oxidative stress and neurocyte apoptosis to exert neuroprotective effects by Nrf2 pathway.


Subject(s)
Brain Edema , Brain Injuries , Neuroprotective Agents , Subarachnoid Hemorrhage , Animals , Apoptosis , Brain/metabolism , Brain Edema/drug therapy , Brain Edema/metabolism , Glutathione Transferase/metabolism , Iridoids , Male , NF-E2-Related Factor 2/metabolism , Neuroprotective Agents/metabolism , Neuroprotective Agents/pharmacology , Oxidative Stress , Rats , Rats, Sprague-Dawley , Rats, Wistar , Subarachnoid Hemorrhage/drug therapy , Subarachnoid Hemorrhage/metabolism
9.
Front Pharmacol ; 12: 710487, 2021.
Article in English | MEDLINE | ID: mdl-34393791

ABSTRACT

Maianthemum atropurpureum (Franch) LaFrankie (Asparagaceae), called nibai in Tibetan or dongka in Drung or zhu-ye-cai in local Chinese, is a wild vegetable consumed by the Tibetan people and other ethnic groups in Northwest Yunnan, China. It is also a traditional medicinal plant used by different linguistic groups for antimicrobial purposes. However the nutritional and phytochemical compositions of this important medicinal food plant have not been well studied previously. In this study, the nutrient content for nibai was determined by the China National Standards (GB) methods, and the phytochemical analysis involved multiple chromatographic and spectral methods including LC-TOF-MS analysis. Dried nibai is a rich source of protein (ca. 24.6%), with 18 of the 21 common amino acids. The amino acid content of nibai can reach up to 17.9/100 g, with the essential amino acids as major contributors, corresponding to 42.3% of the total amino acids. Nibai contains rich mineral elements, dietary fiber, vitamins, ß-carotene, carbohydrates, and lipids. The phytochemical content of nibai was examined by conventional isolation strategies, as well as HR-ESI-TOF-MS to detect and identify 16 compounds including nine steroid saponins and seven flavonoids. Among these compounds, uridine, adenosine, guanosine, and ß-methyl-6-methyl-d-glucopyranoside were found from the genus Maianthemum for the first time. These results help to demonstrate that the local people's practice of consuming Maianthemum atropurpureum is reasonable due to its high levels of vitamins, minerals, essential amino-acids, and phytochemicals. Nibai may be further developed in Tibet and surrounding regions, and beyond as a health food, nutraceutical, and/or dietary supplement product.

10.
ACS Omega ; 6(23): 15472-15478, 2021 Jun 15.
Article in English | MEDLINE | ID: mdl-34151125

ABSTRACT

Metabolite mining of environmentally collected aquatic and marine microbiomes offers a platform for the discovery of new therapeutic lead molecules. Combining a prefractionated chromatography library with liquid chromatography tandem mass spectrometry (LC-MS/MS)-based molecular networking and biological assays, we isolated and characterized two new micropeptins (1 and 2) along with the previously characterized micropeptin 996. These metabolites showed potency in anti-neuroinflammatory assays using BV-2 mouse microglial cells, showing a 50% reduction in inflammation in a range from 1 to 10 µM. These results show promise for cyanobacterial peptides in the therapeutic realm apart from their impact on environmental health and provide another example of the utility of large prefractionated natural product libraries for therapeutic hit and lead identification.

12.
Medicine (Baltimore) ; 100(9): e25053, 2021 03 05.
Article in English | MEDLINE | ID: mdl-33655984

ABSTRACT

RATIONALE: With the easy access, rodenticide poisoning has been a public health problem in many countries. Characteristics of central nervous system (CNS) lesions induced by rodenticides are scarcely reported. PATIENT CONCERNS: We presented a case of a 40-year-old man with seizure and consciousness disorder, coagulation dysfunction, and symmetric lesions in white matter and corpus callosum. DIAGNOSIS: He was diagnosed with rodenticide poisoning due to bromadiolone and fluoroacetamide. INTERVENTIONS: He was treated with vitamin K, hemoperfusion, acetamide, and calcium gluconate. OUTCOMES: His leukoencephalopathy was reversed rapidly with the improvement of clinical symptoms. LESSONS: This report presented the impact of rodenticide poisoning on CNS and the dynamic changes of brain lesions, and highlighted the importance of timely targeted treatments.


Subject(s)
4-Hydroxycoumarins/poisoning , Blood Coagulation/drug effects , Fluoroacetates/poisoning , Leukoencephalopathies/chemically induced , Adult , Humans , Leukoencephalopathies/blood , Male , Rodenticides/poisoning
13.
Front Neurol ; 11: 580777, 2020.
Article in English | MEDLINE | ID: mdl-33329323

ABSTRACT

Refractory status epilepticus (RSE) is a critical and intractable neurological emergency. Around 55% of RSE episodes still persist despite high dose of continuous infusion of anesthetics. It's a clinical urgency and challenge to search for novel alternative treatments to control RSE as soon as possible. Here, we reported a case of RSE in a 67-year-old woman with varicella-zoster virus encephalitis. She had persistent non-convulsive SE despite the continuous infusion of midazolam. On the basis of fundamental treatments, she was given electroacupuncture at Shuigou acupoint for 10 min. An immediate EEG suppression was seen after the electroacupuncture treatment and lasted for 9 min, and lasting epileptic discharges (> 10 s) and clinical seizures were not observed any more. Midazolam was withdrawn gradually 24 h later. This case report may bring an alternative treatment for RSE.

15.
Spectrochim Acta A Mol Biomol Spectrosc ; 226: 117594, 2020 Feb 05.
Article in English | MEDLINE | ID: mdl-31629278

ABSTRACT

Inspired by the conversion from organics or biomass to fluorescent carbon dots (C-dots), the use of pesticide 4-chlorophenol (4-CP) as a precursor to prepare C-dots has been reported. The as-prepared chlorine-doped C-dots display a brightly blue emission at ∼445 nm with ∼22.8% quantum yield. Also, the surface of C-dots enriches functional groups, such as phenolic hydroxyl and carboxylic acid, etc., which can capture ferric ion (Fe(III)), resulting in the quenching of blue fluorescence of C-dots through an inner filter effect. The quantitative assay for Fe(III) was therefore realized by this probe with a 0.36 µM detection limit in the 0.6-25 µM concentration range. Most significantly, the cytotoxicity on Hela cells indicates the 4-CP-derived C-dots have a negligible cytotoxicity. The C-dots were applied in detection in environmental samples and imaging in Hela cells of Fe(III), demonstrating their good applicability, low toxicity and good biocompatibility, and providing an alterative approach to totally eliminate the harm of chlorophenols (CPs).


Subject(s)
Chlorine/chemistry , Chlorophenols/chemistry , Ferric Compounds/analysis , Iron/analysis , Quantum Dots/chemistry , Biosensing Techniques/methods , Ferric Compounds/chemistry , Ferric Compounds/isolation & purification , HeLa Cells , Humans , Iron/chemistry , Iron/isolation & purification , Limit of Detection , Pesticides/chemistry , Single-Cell Analysis/methods , Spectrometry, Fluorescence/methods , Wastewater/chemistry
16.
BMC Chem ; 13(1): 47, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31384795

ABSTRACT

The medicinal plant Tirpitzia sinensis has been used by the Zhuang ethnic people in mountainous areas of Southwest China to stop bleeding, invigorate blood circulation, and treat inflammation and wounds. In order to further explore its traditional medicinal uses, the phytochemical constituents of this species were examined. Three new compounds, the lignan tirpitzin (1), the flavonoid tirpitzoside (2), and the furan-glycoside tirpitziol (3), along with five known compounds were isolated from the aerial part of T. sinensis for the first time. The structures of these compounds were elucidated by 1D and 2D NMR, LC/MS, IR spectrometric methods and compared with published data. The results of an in silico pharmacophore-based analysis showed potential targets of the new compounds, including ERBB2, IRAK4, LCK, JAK2, MAPK14, and MMP-12. These targets suggested that 1-3 may be involved with wound-healing and/or inflammation, leading to an in vitro assay of nitric oxide (NO) inhibition assays with lipopolysaccharide-induced BV-2 cells. All three new compounds displayed moderate NO inhibitory activity with the IC50 values of 14.97 ± 0.87, 26.63 ± 1.32, and 17.09 ± 2.3 µM, respectively.

17.
J Agric Food Chem ; 67(5): 1513-1520, 2019 Feb 06.
Article in English | MEDLINE | ID: mdl-30675793

ABSTRACT

Myrciaria cauliflora (jaboticaba) is an edible fruit common in Brazil that has been used for treating respiratory diseases, including chronic tonsillitis and asthma. This study explores the distribution of an anti-inflammatory depside, jaboticabin, in different parts of the jaboticaba plant as well as major polyphenols from the wood of jaboticaba, some with biological activity similar to jaboticabin. The peel of the fruit was found to be the major source of jaboticabin. This is the first phytochemical study of the wood of M. cauliflora. The antioxidant-activity-guided fractionation strategy successfully identified 3,3'-dimethylellagic acid-4- O-sulfate from jaboticaba wood. This ellagic acid derivative, in a manner similar to jaboticabin, showed antiradical activity and inhibited the production of the chemokine interleukin-8 after treating the human small airway epithelial cells with cigarette smoke extract. The human intestinal Caco-2 cell studies demonstrated the jaboticabin transport in vitro. The polyphenols, jaboticabin and 3,3'-dimethyellagic acid-4- O-sulfate, from jaboticaba were both found to exhibit anti-inflammatory activities, thus suggesting the potential use of these compounds or even the fruits themselves for chronic obstructive pulmonary disease.


Subject(s)
Anti-Inflammatory Agents/pharmacology , Hydroxybenzoates/pharmacology , Myrtaceae/chemistry , Plant Extracts/pharmacology , Polyphenols/pharmacology , Anti-Inflammatory Agents/chemistry , Anti-Inflammatory Agents/isolation & purification , Brazil , Caco-2 Cells , Fruit/chemistry , Humans , Hydroxybenzoates/chemistry , Hydroxybenzoates/isolation & purification , Plant Extracts/chemistry , Plant Extracts/isolation & purification , Polyphenols/chemistry , Polyphenols/isolation & purification , Pulmonary Disease, Chronic Obstructive/drug therapy , Pulmonary Disease, Chronic Obstructive/immunology
18.
J Nat Prod ; 81(11): 2576-2581, 2018 11 26.
Article in English | MEDLINE | ID: mdl-30369239

ABSTRACT

Cyanobufalins A-C (1-3), a new series of cardiotoxic steroids, have been discovered from cyanobacterial blooms in Buckeye Lake and Grand Lake St. Marys in Ohio. Compounds 1-3 contain distinctive structural features, including geminal methyl groups at C-4, a 7,8 double bond, and a C-16 chlorine substituent that distinguish them from plant- or animal-derived congeners. Despite these structural differences, the compounds are qualitatively identical to bufalin in their cytotoxic profiles versus cell lines in tissue culture and cardiac activity, as demonstrated in an impedance-based cellular assay conducted with IPSC-derived cardiomyocytes. Cyanobufalins are nonselectively toxic to human cells in the single-digit nanomolar range and show stimulation of contractility in cardiomyocytes at sub-nanomolar concentrations. The estimated combined concentration of 1-3 in the environment is in the same nanomolar range, and consequently more precise quantitative analyses are recommended along with more detailed cardiotoxicity studies. This is the first time that cardioactive steroid toxins have been found associated with microorganisms in an aquatic environment. Several factors point to a microbial biosynthetic origin for the cyanobufalins.


Subject(s)
Cyanobacteria/metabolism , Harmful Algal Bloom , Heart/drug effects , Toxins, Biological/toxicity , Humans
19.
Materials (Basel) ; 11(10)2018 Sep 25.
Article in English | MEDLINE | ID: mdl-30257477

ABSTRACT

The laser scanning strategy has an important influence on the surface quality, residual stress, and deformation of the molten metal (deformation behavior). A divisional scanning strategy is an effective means used to reduce the internal stress of the selective laser melting (SLM) metal part. In order to understand and optimize the divisional scanning strategy, three divisional scanning strategies and an S-shaped orthogonal scanning strategy are used to produce 316L steel parts in this study. The influence of scanning strategy on the produced parts is verified from the aspects of densification, residual stress distribution and deformation. Experiments show that the 316L steel alloy parts adopted spiral divisional scanning strategy can not only obtain the densification of 99.37%, but they also effectively improve the distribution of residual stress and control the deformation degree of the produced parts. Among them, the spiral divisional scanning sample has the smallest residual stress in plane direction, and its σx and σy stress are controlled within 204 MPa and 103 MPa. The above results show that the spiral divisional scanning is the most conducive strategy to obtain higher residual stress performance of SLM 316L steel parts.

20.
J Nat Prod ; 81(6): 1368-1375, 2018 06 22.
Article in English | MEDLINE | ID: mdl-29847132

ABSTRACT

Four new microcystin congeners are described including the first three examples of microcystins containing the rare doubly homologated tyrosine residue 2-amino-5-(4-hydroxyphenyl)pentanoic acid (Ahppa) (1-4). Large-scale harvesting and biomass processing allowed the isolation of substantial quantities of these compounds, thus enabling complete structure determination by NMR as well as cytotoxicity evaluation against selected cancer cell lines. The new Ahppa-toxins all incorporate Ahppa residues at the 2-position, and one of these also has a second Ahppa at position 4. The two most lipophilic Ahppa-containing microcystins showed 10-fold greater cytotoxic potency against human tumor cell lines (A549 and HCT-116) compared to microcystin-LR (5). The presence of an Ahppa residue in microcystin congeners is difficult to ascertain by MS methods alone, due to the lack of characteristic fragment ions derived from the doubly homologated side chain. Owing to their unexpected cytotoxic potency, the potential impact of the compounds on human health should be further evaluated.


Subject(s)
Cytotoxins/chemistry , Cytotoxins/pharmacology , Microcystins/chemistry , Microcystins/pharmacology , Microcystis/chemistry , Tyrosine/chemistry , A549 Cells , Cell Line, Tumor , HCT116 Cells , Humans , Pentanoic Acids/chemistry , Pentanoic Acids/pharmacology
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