The emerging and legacy persistent organic contaminants in corals of the South China Sea.

Seawater warming, ocean acidification and chemical pollution are the main threats to coral growth and even survival. The legacy persistent organic contaminants (POCs), such as polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), and the emerging contaminants, including polybrominated diphenyl ethers (PBDEs), dechlorane plus (DPs) and novel brominated flame retardants (NBFRs) were studied in corals from Luhuitou fringing reef in Sanya Bay and Yongle atoll in Xisha Islands, the South China Sea (SCS). Total average concentrations of ∑16PAHs, ∑23OCPs, ∑34PCBs, ∑8PBDEs, ∑2DPs and ∑5NBFRs in 20 coral species (43 samples) from the SCS were 40.7 ± 34.6, 5.20 ± 5.10, 0.197 ± 0.159, 3.30 ± 3.70, 0.041 ± 0.042 and 36.4 ± 112 ng g-1 dw, respectively. PAHs and NBFRs were the most abundant compounds and they are likely to be dangerous pollutants for future coral growth. Compared to those found in other coral reef regions, these pollutants concentrations in corals were at low to median levels. Except for PBDEs, POCs in massive Porites were significantly higher than those in branch Acropora and Pocillopora (p < 0.01), as large, closely packed corals may be beneficial for retaining more pollutant. The current study contributes valuable data on POCs, particularly for halogenated flame retardants (HFRs, including PBDEs, DPs and NBFRs), in corals from the SCS, and will improve our knowledge of the occurrence and fate of these pollutants in coral reef ecosystems.

Mass spectrometry-based metabolomic signatures of coral bleaching under thermal stress.

Coral bleaching caused by climate change has resulted in large-scale coral reef decline worldwide. However, the knowledge of physiological response mechanisms of scleractinian corals under high-temperature stress is still challenging. Here, untargeted mass spectrometry-based metabolomics combining with Global Natural Product Social Molecular Networking (GNPS) was utilized to investigate the physiological response of the coral species Pavona decussata under thermal stress. A wide variety of metabolites (including lipids, fatty acids, amino acids, peptides, osmolytes) were identified as the potential biomarkers and subjected to metabolic pathway enrichment analysis. We discovered that, in the thermal-stressed P. decussata coral holobiont, (1) numerous metabolites in classes of lipids and amino acids significantly decreased, indicating an enhanced lipid hydrolysis and aminolysis that contributed to up-regulation in gluconeogenesis to meet energy demand for basic survival; (2) pantothenate and panthenol, two essential intermediates in tricarboxylic acid (TCA) cycle, were up-regulated, implying enhanced efficiency in energy production; (3) small peptides (e.g., Glu-Leu and Glu-Glu-Glu-Glu) and lyso-platelet-activating factor (lysoPAF) possibly implicated a strengthened coral immune response; (4) the down-regulation of betaine and trimethylamine N-oxide (TMAO), known as osmolyte compounds for maintaining holobiont homeostasis, might be the result of disruption of coral holobiont.

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Given its high root regeneration ability and adaptation capacity, Spartina alterniflora would predominate the resource competition with other plant species. As an invasive alien species, it has caused serious damages to the coastal ecosystem of China. We explored the impacts of S. alterniflora invasion on the growth and expansion of mangroves around the coastal zones around Guangxi Shankou Mangrove National Nature Reserve (GSMNNR). The area of S. alterniflora and mangroves in the GSMNNR was analyzed based on a sequence of Landsat satellite multispectral images collected during 1995 to 2019. The results showed that S. alterniflora predominated in the competition with mangroves without human intervention. The area of S. alterniflora decreased under the conditions of cutting, rooting and other management measures, while the average annual growth rate of mangrove area correspondingly increased. It indicated that the invasion of S. alterniflora would inhibit the growth and expansion of mangroves. The S. alterniflora management measures, such as mowing and rooting, could weaken the negative impacts of S. alterniflora on mangroves. Mangroves could thus be effectively protected. This study could provide quantitative scientific data for S. alterniflora management and the protection of the mangrove ecosystem in the GSMNNR, and thus be a valuable reference to the prevention on a larger scale of S. alterniflora and the formulation of further protective measures for mangroves.

Occurrence, source apportionment and risk assessment of antibiotics in water and sediment from the subtropical Beibu Gulf, South China.

The widespread use of antibiotics has raised global concerns, but scarce information on antibiotics in the subtropical marine environment is available. In the present study, seawater and sediment samples were collected to investigate the occurrence, spatial distribution, source, and ecological risks of 22 antibiotics in the Beibu Gulf. The total concentrations of target antibiotics (∑antibiotics) were in the range of 1.74 ng/L to 23.83 ng/L for seawater and 1.33 ng/g to 8.55 ng/g dry weight (dw) for sediment. Spatially, a decreasing trend of antibiotic levels from coast to offshore area was observed, with relatively high levels at the sites close to the Qinzhou Bay and Qiongzhou Strait. Sulfamethoxazole (SMX), trimethoprim (TMP), and norfloxacin (NOX) were predominant in seawater, while NOX, enoxacin (ENX), and enrofloxacin (ENR) were the most abundant antibiotics in sediment. In general, the sediment-water partitioning coefficients (Kd) were positively correlated with log molecular weight (MW). Salinity, particle size, and pH of water were predicted to be vital factors influencing the partition of sulfadiazine (SDZ), CIX, and ENR (p < 0.05). Livestock and aquaculture were identified as dominant sources of antibiotics in the Beibu Gulf based on PCA-MLR and Unmix model. Risk assessment revealed that SMX, CIX could pose medium risks to algae in the Beibu Gulf. Overall, our results provided paramount insights into understanding the fate and transport behaviors of antibiotics in the subtropical marine environment.

Automated µFTIR Imaging Demonstrates Taxon-Specific and Selective Uptake of Microplastic by Freshwater Invertebrates.

Microplastic particles can be deposited to sediments and subsequently ingested by benthic organisms. It is unknown to what extent ingestion of microplastic is taxon-specific or whether taxa can be selective toward certain types of microplastics. Here, we used state-of-the-art automated micro-Fourier-transform infrared (µFTIR) imaging and attenuated total reflectance FTIR spectroscopy to determine small-size (20-500 µm) and large-size (500-5000 µm) microplastic particles in sediments and a range of benthic invertebrate species sampled simultaneously from the Dommel River in the Netherlands. Microplastic number concentrations differed across taxa at the same locations, demonstrating taxon-specific uptake, whereas size distributions were the same across sediments and taxa. At the site with the highest concentration, microplastic occupied up to 4.0% of the gut volume of Asellidae. Particle shape distributions were often not statistically different between sediments and taxa, except for Astacidea at one of the locations where the proportion of particles with a length to width ratio >3 (i.e., fibers) was twice as high in sediments than in Astacidea. Acrylates/polyurethane/varnish was predominately found in sediments, while soft and rubbery polymers ethylene propylene diene monomer and polyethylene-chlorinated were the dominant polymers found in invertebrates. Microplastic polymer composition and thus polymer density differed significantly between invertebrates and their host sediment. Trophic transfer at the base of the food web appears to have a filter function with respect to microplastic particle types and shapes. Together with the very high ingestion rates, this has clear implications for ecological and human health risks, where uptake concerns edible species (e.g., Astacidea).

Distribution, partitioning behavior and potential source of legacy and alternative per- and polyfluoroalkyl substances (PFASs) in water and sediments from a subtropical Gulf, South China Sea.

Legacy per- and polyfluoroalkyl acids (PFASs) have received global concern over the scientific and public community since this century. However, the information on alternative PFASs pollution in the marine environment, especially in the subtropical marine environment is extremely limited. This study investigated the occurrence, partitioning, potential sources, and ecological risks of PFASs, including perfluoroalkane sulfonic acids (PFSAs), perfluoroalkyl carboxylic acids (PFCAs), and alternative PFASs, in surface water and sediments from the subtropical Beibu Gulf, South China. Concentrations of total PFASs (∑PFASs) were in the range of 0.98-2.64 ng/L in water and 0.19-0.66 ng/g (dry weight, dw) in sediment, respectively. Perfluorooctanoic acid (PFOA) was the most abundant PFAS in water, while PFASs in sediment were dominated by perfluorooctanesulfonic acid (PFOS) and PFOA. Among investigated environmental parameters (total organic carbon (TOC), grain size, water pH, sediment pH, and salinity), TOC and salinity were the dominant factors influencing the sediment-water distribution coefficient (Kd) of PFOA, perfluorodecanoic acid (PFDA), and perfluorononanoic acid (PFNA). Log Kd and log soil organic carbon-water distribution coefficient (Koc) both increase with increasing carbon chain length of PFASs. Significantly positive correlations between PFOS and perfluorohexanoic acid (PFHxA) (p < 0.05), PFOA and perfluoro-1-butane-sulfonamide (FBSA) were observed, suggesting that these PFASs might have similar sources and transport routes. Preliminary environmental risk assessment showed that PFOA and PFOS would not pose risks to the marine aquatic environment. This is the first comprehensive survey of legacy and alternative PFASs in a subtropical area of the Beibu Gulf, which provides significant data and scientific basis to better understand the fate of PFASs and pollution control management.

Antibiotics in a subtropical food web from the Beibu Gulf, South China: Occurrence, bioaccumulation and trophic transfer.

Antibiotics are of particular concern because of their ubiquity in aquatic environment and long-term adverse effects on aquatic organisms and humans. However, there is no information about the bioaccumulation and trophic magnification of antibiotics in subtropical environments. In this study, we determined the concentrations of 22 antibiotics to investigate their occurrence, bioaccumulation and trophic magnification in a subtropical food web from the Beibu Gulf. The total concentrations of target antibiotics ranged from 52.94-77.76 ng/L in seawater, 9.69-15.43 ng/g dry weight (dw) in sediment, and 0.68-4.75 ng/g wet weight (ww) in marine organisms, respectively. Macrolides were the predominant antibiotics in water, while fluoroquinolones were more abundant in sediment and biota samples. The total concentrations of target antibiotics in examined marine taxa descended in the order: crustacean > cephalopod > fish, with antibiotic profiles displaying distinct difference among taxa. Log BAFs (bioaccumulation factor) for antibiotics in all organisms ranged from -0.50 for erythromycin-H2O (ETM-H2O) to 2.82 for sulfamonomethoxine (SMM). Significantly negative correlation was observed between the log Dow and log BAF values (p < .05), indicating that log Dow is a good predictor of antibiotics bioaccumulation potential in marine organisms. The trophic magnification factors (TMFs) for sulfadiazine (SDZ) and enoxacin (ENX) were greater than unity, suggesting the trophic magnification of these chemicals through the food web. In contrast, enrofloxacin (ENR), ciprofloxacin (CIX), ofloxacin (OFX), norfloxacin (NOX), ETM-H2O and trimethoprim (TMP) were biodiluted in the food web from the Beibu Gulf. This study provides substantial information on the fate and trophic transfer of antibiotics in a subtropical marine ecosystem.

Legacy and alternative per- and polyfluoroalkyl substances in a subtropical marine food web from the Beibu Gulf, South China: Fate, trophic transfer and health risk assessment.

The usage of alternative per- and polyfluoroalkyl substances (PFASs) has been increasing due to the restriction and elimination of legacy PFASs. However, there is limited knowledge on bioaccumulation and trophic magnification of alternative PFASs, especially in subtropical ecosystems. In the present study, we performed a comprehensive survey to investigate the occurrence, bioaccumulation and trophic magnification of legacy and alternative PFASs in subtropical marine food webs in the Beibu Gulf, South China. Results showed that perfluorobutanoic acid (PFBA) and perfluorooctanoic acid (PFOA) were the predominant PFASs in water phase, while perfluorooctane sufonate (PFOS) contributed most to the sum of target PFASs in sediments and marine organisms. Of the investigated PFASs, PFOS and 6:2 chlorinated polyfluoroalkyl ether sulfonic acids (F-53B) exhibited the highest bioaccumulation factor with values > 5000, qualifying as very bioaccumulative chemicals. There was a significant positive correlation between log BSAF and the carbon chain length of perfluoroalkyl carboxylic acids (PFCAs). Trophic magnification (TMF) was observed for PFOS and F-53B, while the remaining PFASs were biodiluted through the present food web. The hazard ratios for PFOS and PFOA in all organisms were far less than unity, suggesting overall low PFAS risks for humans through consumption of marine organisms.

Occurrence and distribution of perfluoroalkyl substances in surface riverine and coastal sediments from the Beibu Gulf, south China.

There is limited understanding on the occurrence of PFASs in coastal sediment, especially in less-developed coastal areas. Here, we collected surface sediment samples from the Beibu Gulf to investigate the occurrence, spatial distribution and environmental risks of 18 PFASs. The concentrations of the total PFASs (ΣPFASs) ranged from 56.2 to 586.3 pg/g dry weight (dw), with a mean value of 172.5 pg/g dw. ΣPFASs concentrations were significantly lower in riverine than in coastal sediments. Additionally, there was a decreasing trend in ΣPFASs concentrations from the west (Fangchenggang) to the east (Beihai) of the Beibu Gulf. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were the predominant PFASs, with their concentrations in the range of 4.8-249.0 pg/g dw and not detected (n.d)-224.8 pg/g dw, respectively. On a global scale, PFOS and PFOA concentrations were at low levels in the sediment of the Beibu Gulf, and they posed negligible environmental risks.

Perfluoroalkyl substances in the riverine and coastal water of the Beibu Gulf, South China: Spatiotemporal distribution and source identification.

Few studies have examined the perfluoroalkyl substances (PFASs) contamination in less-developed coastal regions. In the present study, we collected 19 riverine and 21 coastal surface water samples in the summer and winter of 2017 to investigate PFASs contamination in the Beibu Gulf, South China. The results show that eleven and twelve target PFASs were detected in the summer and winter, respectively. The total PFASs (ΣPFASs) concentrations in the water of the Beibu Gulf were in the range of 1609-4727 pg/L and 610-4920 pg/L in summer and winter, respectively. Perfluoropentanoic acid (PFPeA), perfluorobutanoic acid (PFBA) and perfluorobutane sulfonate (PFBS) were the predominantly detected PFASs in both seasons with maximum concentrations of 2968 pg/L, 1771 pg/L, and 1764 pg/L, respectively. Strong positive correlations between some PFASs were observed (e.g., PFBA and PFBS, PFOS and PFBS, p < 0.05), suggesting these correlated pollutants may share similar sources. PFASs contamination in the Beibu Gulf was strongly affected by ocean currents, and their concentrations were lower than most coastal waters around the world. Risk assessment indicates a low risk associated with target PFASs to aquatic organisms in the Beibu Gulf. The results of the present research provided a baseline and good overview of the spatial distribution of PFASs along the Beibu Gulf.

Species-specific profiles and risk assessment of perfluoroalkyl substances in coral reef fishes from the South China Sea.

The contamination profiles of sixteen perfluoroalkyl substances (PFAS) were examined in coral reef fish samples collected from the South China Sea (SCS) where no information about this topic was available in the literature. The results revealed that six PFAS were found in coral reef fish samples from the SCS. Perfluorooctane sulfonate (PFOS) was the most predominant PFAS contaminant detected in most of the samples, with the highest concentration value of 27.05 ng/g wet weight (ww) observed in Cephalopholis urodelus. Perfluoroundecanoic acid (PFUnDA) and Perfluorotridecanoic acid (PFTrDA) were the second and third dominant PFAS, respectively. Mean PFOS concentrations in muscle of seven coral reef fish varied from 0.29 ng/g ww in Lethrinus olivaceus to 10.78 ng/g ww in Cephalopholis urodelus. No significant linear relationship was observed between PFOS levels and coral reef fish traits (length, weight) collected in this region. Average daily intake of PFOS for the seven coral reef fishes ranged from 0.79 ng/kg/d for Lethrinus olivaceus to 29.53 ng/kg/d for Cephalopholis urodelus. The hazard ratio (HR) values for human consumption of PFOS-contaminated coral reef fishes ranged from 0.04 to 1.48, with Cephalopholis urodelus having the highest HR value of 1.18 (higher than 1) among the species, indicating frequent consumption of Cephalopholis urodelus might pose potential health risk to local population. The present work have provided the first hand data of PFAS in coral reef fishes in the SCS and indirectly demonstrated the existence of low level PFAS pollution in the SCS in China.

Coral trace metal of natural and anthropogenic influences in the northern South China Sea.

The composition and concentrations of trace metals in coastal seawater have changed in parallel with variations in geochemical processes, climate and anthropogenic activities. To evaluate the response of trace metals in coastal seawater to climatic changes and human disturbances, we report annual-resolution trace element data for a Porites coral core covering ~100years of continuous growth from a fringing reef in Xiaodonghai Bay in the northern South China Sea. The results suggested that the trace metal contents in the coral skeleton demonstrated decadal to interdecadal fluctuations with several large or small peaks in certain years with remarkable environmental significances. All of the trace metals in coastal surface seawater, especially Cr and Pb (related to industrial or traffic emissions), were impacted by terrestrial inputs, except for Sr and U, which were impacted by the surface seawater temperature (SST). Moreover, Mn, Ni, Fe and Co were also contributed by weapons and military supplies during wars, and Cu, Cd and Zn were further impacted by upwelling associated with their biogeochemical cycles. Ba and rare earth element (REE) in coastal surface seawater were dominated by runoff and groundwater discharge associated with precipitation. This study provided the potential for some trace metals (e.g., REE, Ba, Cu, Cd, and Zn) in coral skeletons to be used as proxies of natural (e.g., upwelling and precipitation) and anthropogenic (e.g., war and coastal construction) variability of seawater chemistry to enable the reconstruction of environmental and climatic changes through time.

Does ligand-receptor mediated competitive effect or penetrating effect of iRGD peptide when co-administration with iRGD-modified SSL?

Ligand-mediated targeting of anticancer therapeutic agents is a useful strategy for improving anti-tumor efficacy. It has been reported that co-administration of a tumor-penetrating peptide iRGD (CRGDK/RGPD/EC) enhances the efficacy of anticancer drugs. Here, we designed an experiment involving co-administration of iRGD-SSL-DOX with free iRGD to B16-F10 tumor bearing mice to examine the action of free iRGD. We also designed an experiment to investigate the location of iRGD-modified SSL when co-administered with free iRGD or free RGD to B16-F10 tumor bearing nude mice. Considering the sequence of iRGD, we selected the GPDC, RGD and CRGDK as targeting ligands to investigate the targeting effect of these peptides compared with iRGD on B16-F10 and MCF-7 cells, with or without enzymatic degradation. Finally, we selected free RGD, free CRGDK and free iRGD as ligand to investigate the inhibitory effect on RGD-, CRGDK- or iRGD-modified SSL on B16-F10 or MCF-7 cells. Our results indicated that iRGD targeting to tumor cells was ligand-receptor mediated involving RGD to αv-integrin receptor and CRGDK to NRP-1 receptor. Being competitive effect, the administration of free iRGD would not be able to further enhance the anti-tumor activity of iRGD-modified SSL. There is no need to co-administrate of free iRGD with the iRGD-modified nanoparticles for further therapeutic benefit.

The antitumor activity of a doxorubicin loaded, iRGD-modified sterically-stabilized liposome on B16-F10 melanoma cells: in vitro and in vivo evaluation.

Considering the fact that iRGD (tumor-homing peptide) demonstrates tumor-targeting and tumor-penetrating activity, and that B16-F10 (murine melanoma) cells overexpress both αv integrin receptor and neuropilin-1 (NRP-1), the purpose of this study was to prepare a novel doxorubicin (DOX)-loaded, iRGD-modified, sterically-stabilized liposome (SSL) (iRGD-SSL-DOX) in order to evaluate its antitumor activity on B16-F10 melanoma cells in vitro and in vivo. The iRGD-SSL-DOX was prepared using a thin-film hydration method. The characteristics of iRGD-SSL-DOX were evaluated. The in vitro leakage of DOX from iRGD-SSL-DOX was tested. The in vitro tumor-targeting and tumor-penetrating characteristics of iRGD-modified liposomes on B16-F10 cells were investigated. The in vivo tumor-targeting and tumor-penetrating activities of iRGD-modified liposomes were performed in B16-F10 tumor-bearing nude mice. The antitumor effect of iRGD-SSL-DOX was evaluated in B16-F10 tumor-bearing C57BL/6 mice in vivo. The average particle size of the iRGD-SSL-DOX was found to be 91 nm with a polydispersity index (PDI) of 0.16. The entrapment efficiency of iRGD-SSL-DOX was 98.36%. The leakage of DOX from iRGD-SSL-DOX at the 24-hour time point was only 7.5%. The results obtained from the in vitro flow cytometry and confocal microscopy, as well as in vivo biodistribution and confocal immunofluorescence microscopy experiments, indicate that the tumor-targeting and tumor-penetrating activity of the iRGD-modified SSL was higher than that of unmodified SSL. In vivo antitumor activity results showed that the antitumor effect of iRGD-SSL-DOX against melanoma tumors was higher than that of SSL-DOX in B16-F10 tumor-bearing mice. In conclusion, the iRGD-SSL-DOX is a tumor-targeting and tumor-penetrating peptide modified liposome which has significant antitumor activity against melanoma tumors.

Antitumor activity of dichloroacetate on C6 glioma cell: in vitro and in vivo evaluation.

Dichloroacetate (DCA), a small molecule mitochondria-targeting agent, can penetrate the blood-brain barrier, showing potential therapeutic effects on brain tumors. Considering the effects of DCA on tumor cellular metabolism, penetrating across the blood-brain barrier, as well as having potential antitumor activity on brain tumors, the purpose of this study is to investigate the antitumor activity of DCA on C6 glioma cells in vitro and in vivo. DCA inhibited C6 glioma cell proliferation, induced C6 cell apoptosis, and arrested C6 cells in S phase. DCA can inhibit the expression of heat shock proteins 70 (Hsp70) in a dose-dependent and time-dependent manner (P < 0.01). Our in vivo antitumor effect results indicated that DCA markedly inhibited the growth of C6 glioma tumors in both C6 brain tumor-bearing rats and C6 tumor-bearing nude mice (P < 0.01). DCA significantly induced the ROS production and decreased the mitochondrial membrane potential in tumor tissues. Our in vivo antitumor effect results also indicated that DCA has potential antiangiogenic effects. In conclusion, DCA may be a viable therapeutic agent in the treatment of gliomas.

Anti-tumor and anti-angiogenic effect of metronomic cyclic NGR-modified liposomes containing paclitaxel.

In the present study, we prepared NGR-modified sterically stabilized liposomes containing paclitaxel (NGR-SSL-PTX) in order to evaluate their potential targeting to aminopeptidase N receptors expressed on tumor endothelial cells and the tumor cell surface and its anti-angiogenic activity following metronomic administration. NGR-SSL-PTX was prepared by a thin-film hydration method. The in vitro targeting characteristics of NGR-modified liposomes on HUVEC (human umbilical vein endothelial cells), HT1080 (human fibrosarcoma cells) and MCF-7 (human breast adenocarcinoma cells) were then investigated. The effect of NGR-SSL-PTX on HUVEC proliferation and migration was also tested. The pharmacokinetics of NGR-SSL-PTX was studied in rats. The in vivo targeting activity of NGR-modified liposomes was investigated in HT1080 tumor-bearing mice. The anti-tumor activity of NGR-SSL-PTX following metronomic administration was evaluated in HT1080 tumor-bearing mice in vivo. The targeting activity of the NGR-modified liposomes was demonstrated by in vitro flow cytometry and confocal microscopy as well as in vivo confocal immunofluorescence microscopy and bio-distribution experiments. The results of endothelial cell proliferation and migration and microvessel density (MVD) confirmed the anti-angiogenic activity of NGR-SSL-PTX in vitro and in vivo. The sustained circulation of NGR-SSL-PTX was shown in the pharmacokinetic study. NGR-SSL-PTX is able to improve treatment efficacy producing the most significant anti-tumor activity and anti-angiogenic following metronomic administration.

Antitumor efficacy of a novel CLA-PTX microemulsion against brain tumors: in vitro and in vivo findings.

BACKGROUND: Considering the observations that linoleic acid conjugated with paclitaxel (CLA-PTX) possesses antitumor activity against brain tumors, is able to cross the blood-brain barrier, but has poor water solubility, the purpose of this study was to prepare a novel CLA-PTX microemulsion and evaluate its activity against brain tumors in vitro and in vivo. METHODS: The in vitro cytotoxicity of a CLA-PTX microemulsion was investigated in C6 glioma cells. The in vivo antitumor activity of the CLA-PTX microemulsion was evaluated in tumor-bearing nude mice and rats. The pharmacokinetics of the CLA-PTX microemulsion were investigated in rats, and its safety was also evaluated in mice. RESULTS: The average droplet size of the CLA-PTX microemulsion was approximately 176.3 ± 0.8 nm and the polydispersity index was 0.294 ± 0.024. In vitro cytotoxicity results showed that the IC(50) of the CLA-PTX microemulsion was 1.61 ± 0.83 µM for a C6 glioma cell line, which was similar to that of free paclitaxel and CLA-PTX solution (P > 0.05). The antitumor activity of the CLA-PTX microemulsion against brain tumors was confirmed in our in vivo C6 glioma tumor-bearing nude mice as well as in a rat model. In contrast, Taxol(®) had almost no significant antitumor effect in C6 glioma tumor-bearing rats, but could markedly inhibit growth of C6 tumors in C6 glioma tumor-bearing nude mice. The pharmacokinetic results indicated that CLA-PTX in solution has a much longer circulation time and produces higher drug plasma concentrations compared with the CLA-PTX microemulsion. The results of the acute toxicity study showed that the LD(50) of CLA-PTX solution was 103.9 mg/kg. In contrast, the CLA-PTX microemulsion was well tolerated in mice when administered at doses up to 200 mg/kg. CONCLUSION: CLA-PTX microemulsion is a novel formulation with significant antitumor efficacy in the treatment of brain tumors, and is safer than CLA-PTX solution.

The efficiency of tumor-specific pH-responsive peptide-modified polymeric micelles containing paclitaxel.

The acidic pH in tumor tissues could be used for targeting solid tumors. In the present study, we designed a tumor-specific pH-responsive peptide H(7)K(R(2))(2), which could respond to the acidic pH in tumor tissues, and prepared H(7)K(R(2))(2)-modified polymeric micelles containing paclitaxel (PTX-PM-H(7)K(R(2))(2)) in order to evaluate their potential targeting of tumor cells and tumor endothelial cells and their anti-tumor activity in mice with tumor cells. PTX-PM-H(7)K(R(2))(2) was prepared by a thin-film hydration method. The in vitro release of PTX from PTX-PM-H(7)K(R(2))(2) was tested. The in vitro targeting characteristics of H(7)K(R(2))(2)-modified polymeric micelles on HUVEC (human umbilical vein endothelial cells) and MCF-7 (human breast adenocarcinoma cells) were evaluated. The in vivo targeting activity of H(7)K(R(2))(2)-modified polymeric micelles and the in vivo anti-tumor activity of PTX-PM-H(7)K(R(2))(2) were also investigated in MCF-7 tumor-bearing mice. The released PTX from the PTX-PM-H(7)K(R(2))(2) was not affected by the pH. The targeting activity of the H(7)K(R(2))(2)-modified polymeric micelles was demonstrated by in vitro flow cytometry and confocal microscopy as well as in vivo biodistribution. PTX-PM-H(7)K(R(2))(2) produced very marked anti-tumor and anti-angiogenic activity in MCF-7 tumor-bearing mice in vivo.

Accumulation and partitioning of seven trace metals in mangroves and sediment cores from three estuarine wetlands of Hainan Island, China.

Trace metals in mangrove tissues (leaf, branch, root and fruit) of nine species and sediments of ten cores collected in 2008 from Dongzhai Harbor, Sanya Bay and Yalong Bay, Hainan Island, were analyzed. The average concentrations of Cu, Pb, Zn, Cd, Cr, Hg and As in surface sediments were 14.8, 24.1, 57.9, 0.17, 29.6, 0.08 and 9.7 µg g(-1), whereas those in mangrove tissues were 2.8, 1.4, 8.7, 0.03, 1.1, 0.03, and 0.2 µg g(-1), respectively. Compared to those from other typical mangrove wetlands of the world, the metal levels in Hainan were at low- to median-levels, which is consistent with the fact that Hainan Island is still in low exploitation and its mangroves suffer little impact from human activities. Metal concentrations among different tissues of mangroves were different. In general, Zn and Cu were enriched in fruit, Hg was enriched in leaf, Pb, Cd and Cr were enriched in branch, and As was enriched in root. The cycle of trace metals in mangrove species were estimated. The biota-sediment accumulation factors (BSAFs) followed the sequence of Hg (0.43)>Cu (0.27)>Cd (0.22)>Zn (0.17)>Pb (0.07)>Cr (0.06)>As (0.02).

Heavy metal pollution recorded in Porites corals from Daya Bay, northern South China Sea.

We examined metal-to-calcium ratios (Fe/Ca, Mn/Ca and Zn/Ca) in the growth bands of two Porites corals from Daya Bay, South China Sea, in order to trace long-term trends in local ambient pollution levels. Although Fe and Mn did not show any obvious increasing trends over 32 years in the period 1976-2007, peak values of Fe/Ca and Mn/Ca occurred in the mid-late 1980s, temporally-coeval with the local construction of a nuclear power station. Furthermore, both corals showed rapid increases in Zn concentrations over the past 14 years (1994-2007), most likely due to increases in domestic and industrial sewage discharge. The Daya Bay corals had higher concentrations of metals than other reported corals from both pristine and seriously polluted locations, suggesting that acute (Fe and Mn) and chronic (Zn) heavy metal contamination has occurred locally over the past approximately 32 years.