Organic amendments increased Chinese milk vetch symbiotic nitrogen fixation by enriching Mesorhizobium in rhizosphere

Symbiotic nitrogen fixation of Chinese milk vetch (Astragalus sinicus L.) can fix nitrogen from the atmosphere and serve as an organic nitrogen source in agricultural ecosystems. Exogenous organic material application is a common practice of affecting symbiotic nitrogen fixation; however, the results of the regulation activities remain under discussion. Studies on the impact of organic amendments on symbiotic nitrogen fixation have focused on dissolved organic carbon content changes, whereas the impact on dissolved organic carbon composition and the underlying mechanism remain unclear. In situ pot experiments were carried out using soils from a 40-year-old field experiment platform to investigate symbiotic nitrogen fixation rate trends, dissolved organic carbon concentration and component, and diazotroph community structure in roots and in rhizosphere soils following long-term application of different exogenous organic substrates, i.e., green manure, green manure and pig manure, and green manure and rice straw. Remarkable increases in rate were observed in and when compared with that in green manure treatment, with the greatest enhancement observed in the treatment. Moreover, organic amendments, particularly pig manure application, altered diazotroph community composition in rhizosphere soils, therefore increasing the abundance of the host-specific genus Mesorhizobium. Furthermore, organic amendments influence the diazotroph communities through two primary mechanisms. Firstly, the components of dissolved organic carbon promote an increase in available iron, facilitated by the presence of humus substrates. Secondly, the elevated content of dissolved organic carbon and available iron expands the niche breadth of Mesorhizobium within the rhizosphere. Consequently, these alterations result in a modified diazotroph community within the rhizosphere, which in turn influences Mesorhizobium nodulation in the root and symbiotic nitrogen fixation rate. The results of the present study enhance our understanding of the impact of organic amendments on symbiotic nitrogen fixation and the underlying mechanism, highlighting the key role of dissolved organic carbon composition on diazotroph community composition in the rhizosphere.

No-Reference Quality Assessment of Extended Target Adaptive Optics Images Using Deep Neural Network

This paper proposes a supervised deep neural network model for accomplishing highly efficient image quality assessment (IQA) for adaptive optics (AO) images. The AO imaging systems based on ground-based telescopes suffer from residual atmospheric turbulence, tracking error, and photoelectric noise, which can lead to varying degrees of image degradation, making image processing challenging. Currently, assessing the quality and selecting frames of AO images depend on either traditional IQA methods or manual evaluation by experienced researchers, neither of which is entirely reliable. The proposed network is trained by leveraging the similarity between the point spread function (PSF) of the degraded image and the Airy spot as its supervised training instead of relying on the features of the degraded image itself as a quality label. This approach is reflective of the relationship between the degradation factors of the AO imaging process and the image quality and does not require the analysis of the image's specific feature or degradation model. The simulation test data show a Spearman's rank correlation coefficient (SRCC) of 0.97, and our method was also validated using actual acquired AO images. The experimental results indicate that our method is more accurate in evaluating AO image quality compared to traditional IQA methods.

NIR light, pH, and redox-triple responsive nanogels for controlled release

Herein we report a novel spiropyran (SP)-based organic-inorganic composite nanogel (NG), which was prepared using upconverting nanoparticles, spiropyran, acrylic acid and N,N'-bis(acryloyl)cystamine (BAC) compounds under emulsion polymerisation. Compared with other polymer nanoparticles, the crosslinked multi-stimulus responsive nanogels can adjust the release rate by altering more of the parameters and this can meet the needs of a complex biological environment to control the release of drugs. Doxorubicin hydrochlorides were used as a simulated drug to test the drug loading performance and controllable drug release performance of the composite NGs. Under near-infrared light (NIR) irradiation, an acidic environment or a reducing agent, the delivery of the loaded drugs was by controlled release over 24 hours. Under mild triple stimulation (NIR light, pH 6, and 4 mM reducing agent), the loaded drug could be released more efficiently. The organic-inorganic composite NGs with highly-efficient and controllable release performance for loaded drugs provide many choices for novel stimulus responsive nanocarriers.

ScRNA-Seq Reveals a Distinct Osteogenic Progenitor of Alveolar Bone

The metabolism and remodeling of alveolar bone are the most active among the whole skeletal system, which is related to the biological characteristics and heterogeneity of the bone mesenchymal stromal cells (MSCs). However, there is a lack of systematic description of the heterogeneity of MSC-derived osteoblastic lineage cells as well as their distinct osteogenic differentiation trajectory of alveolar bone. In this study, we constructed a single-cell atlas of the mouse alveolar bone cells through single-cell RNA sequencing (scRNA-seq). Remarkably, by comparing the cell compositions between the alveolar bone and long bone, we uncovered a previously undescribed cell population that exhibits a high expression of protocadherin Fat4 (Fat4⁺ cells) and is specifically enriched around alveolar bone marrow cavities. ScRNA-seq analysis indicated that Fat4⁺ cells may initiate a distinct osteogenic differentiation trajectory in the alveolar bone. By isolating and cultivating Fat4⁺ cells in vitro, we demonstrated that they possess colony-forming, osteogenic, and adipogenic capabilities. Moreover, FAT4 knockdown could significantly inhibit the osteogenic differentiation of alveolar bone MSCs. Furthermore, we revealed that the Fat4⁺ cells exhibit a core transcriptional signature consisting of several key transcription factors, such as SOX6, which are involved in osteogenesis, and further demonstrated that SOX6 is required for the efficient osteogenic differentiation of the Fat4⁺ cells. Collectively, our high-resolution single-cell atlas of the alveolar bone reveals a distinct osteogenic progenitor that may contribute to the unique physiological characteristics of alveolar bone.

Microbial keystone taxa drive succession of plant residue chemistry

Managing above-ground plant carbon inputs can pave the way toward carbon neutrality and mitigating climate change. Chemical complexity of plant residues largely controls carbon sequestration. There exist conflicting opinions on whether residue chemistry diverges or converges after long-term decomposition. Moreover, whether and how microbial communities regulate residue chemistry remains unclear. This study investigated the decomposition processes and residue composition dynamics of maize straw and wheat straw and related microbiomes over a period of 9 years in three climate zones. Residue chemistry exhibited a divergent-convergent trajectory during decomposition, that is, the residue composition diverged during the 0.5-3 year period under the combined effect of straw type and climate and then converged to an array of common compounds during the 3-9 year period. Chemical divergence during the first 2-3 years was primarily driven by the changes in extracellular enzyme activity influenced by keystone taxa-guided bacterial networks, and the keystone taxa belonged to Alphaproteobacteria, particularly Rhizobiales. After 9 years, microbial assimilation became dominant, leading to chemical convergence, and fungi, particularly Chaetomium, were the main contributors to microbial assimilation. Overall, this study demonstrated that keystone taxa regulate the divergent-convergent trajectory in residue chemistry.

Osteoblastic RAR Inhibition Causes VAD-Like Craniofacial Skeletal Deformity

Retinoid signaling disorders cause craniofacial deformity, among which infants with maternal vitamin A deficiency (VAD) exhibited malformation of the eye, nose, palate, and parietal and jaw bone. Previous research uncovered the pathogenesis of eye defect and cleft palate of VAD in mice, but the studies on craniofacial skeletal deformity met obstacles, and the cell/lineage and underlying mechanism remain unclear. The retinoic acid receptor (RAR) is the key transcription factor in retinoid signaling, but individual knockout cannot simulate pathway inhibition. Here, we conditionally expressed dominant-negative RARα mutation (dnRARα) in osteoblasts to specifically inhibit the transcription activity of RAR in mice, which mimics the craniofacial deformities caused by VAD in clinical cases: hypomineralization of cranial bones, mandibular deformity, and clavicular hypoplasia. Furthermore, we performed 3-dimensional reconstruction based on micro-computed tomography and confirmed the abnormalities in the shape, size, and ossification of craniofacial bones due to osteoblastic RAR inhibition. Histological analysis indicated that inhibition of RAR in osteoblasts impaired both bone formation and bone resorption, which was confirmed by transcriptome sequencing of the calvaria. Furthermore, mechanism investigation showed that inhibition of RAR in osteoblasts directly decreased osteoblast differentiation in a cell-autonomous manner by impairing osteogenic gene transcription and also inhibited osteoclast differentiation via osteoblast-osteoclast crosstalk by impairing Rankl transcription. In summary, osteoblastic RAR activity is critical to craniofacial skeletal development, and its dysfunction leads to skeletal deformities mimicking VAD craniofacial defects, providing a new insight for VAD pathogenesis.

EVALUATION OF PRE-ABLATION NLR AND LMR AS PREDICTORS OF DISTANT METASTASES IN PATIENTS WITH DIFFERENTIATED THYROID CANCER

Objective

This research aim was to evaluates the role of the pre-ablation neutrophil-to-lymphocyte ratio (NLR) and lymphocyte-to-monocyte ratio (LMR) as predictors of distant metastases in patients with differentiated thyroid cancer (DTC).

Methods

A retrospective analysis was given to 140 patients with DTC who received 131I remnant ablation after surgery. The patients were divided into two groups based on the existence of distant metastasis.

Results

The two groups showed no significant difference in age, gender, WBCs, neutrophils, monocytes, eosinophils, basophils and whether the tumor was multifocal. In the univariate analysis, significant differences were found in tumor size (p=0.021), lymphocyte (p=0.012), NLR (p=0.027), and LMR (p=0.007). According to the ROC curves, NLR had an AUC of 0.612 ± 0.097 with a cut-off value of 1.845, sensitivity of 60.0%, and specificity of 66.2% (p=0.027). LMR had an AUC of 0.638 ± 0.095 with a cut-off value of 4.630, sensitivity of 84.6%, and specificity of 35.4% (p=0.007). In the multivariate analysis, larger tumor size (OR=5.246, 95% CI 1.269-10.907, p=0.009) and higher NLR (OR=2.087, 95% CI 0.977-4.459, p=0.034) were statistically significant for distant metastases.

Conclusion

This research reveals that pre-ablation NLR and tumor size are significantly statistically correlated with distant metastases in patients with DTC.

Acquirement of HRP conjunct IgG anti-IgMs from most widely cultured freshwater fishes in China and its immunoreactivity

Until now, custom-made or commercial polyclonal antibody against only one kind of fish IgM limited application of the antibody. During our research on development of vaccine against infection of Clonorchis sinensis (C. sinensis) in several kinds of fish, we were conscious of the urgency of secondary antibody to evaluate immune effect and screen C. sinensis infection with immunological technology instead of labor-intensive and time-consuming squash or artificial digestion of fish flesh. So that, we purified IgM of grass carp, bighead carp, crucian carp, common carp and tilapia which were widely cultured freshwater fishes in most areas of China. On this basis, we generated HRP-conjunct rabbit IgG anti-fish IgMs with high titers. IgM of other freshwater fishes including oshima, yellow catfish, bream, silver carp and so on could be recognized by the IgG sensitively. Additionally, The ELISA detection displayed that the IgG could be more specific and sensitive than custom-made rabbit IgG anti-grass carp IgM. The acquirement of HRP-conjunct rabbit IgG anti-fish IgMs was the cornerstone for studying the immune system of teleost fish, developing immunoassay methods and evaluation of fish vaccine with more convenience.

Gene Flow Risks From Transgenic Herbicide-Tolerant Crops to Their Wild Relatives Can Be Mitigated by Utilizing Alien Chromosomes

Integration of a transgene into chromosomes of the C-genomes of oilseed rape (AACC, 2n = 38) may affect their gene flow to wild relatives, particularly Brassica juncea (AABB, 2n = 36). However, no empiric evidence exists in favor of the C-genome as a safer candidate for transformation. In the presence of herbicide selections, the first- to fourth-generation progenies of a B. juncea × glyphosate-tolerant oilseed rape cross [EPSPS gene insertion in the A-genome (Roundup Ready, event RT73)] showed more fitness than a B. juncea × glufosinate-tolerant oilseed rape cross [PAT gene insertion in the C-genome (Liberty Link, event HCN28)]. Karyotyping and fluorescence in situ hybridization-bacterial artificial chromosome (BAC-FISH) analyses showed that crossed progenies from the cultivars with transgenes located on either A- or C- chromosome were mixoploids, and their genomes converged over four generations to 2n = 36 (AABB) and 2n = 37 (AABB + C), respectively. Chromosome pairing of pollen mother cells was more irregular in the progenies from cultivar whose transgene located on C- than on A-chromosome, and the latter lost their C-genome-specific markers faster. Thus, transgene insertion into the different genomes of B. napus affects introgression under herbicide selection. This suggests that gene flow from transgenic crops to wild relatives could be mitigated by breeding transgenic allopolyploid crops, where the transgene is inserted into an alien chromosome.

Visible-light-triggered supramolecular valves based on β-cyclodextrin-modified mesoporous silica nanoparticles for controlled drug release

Visible-light triggered drug delivery system based on tetra-ortho-methoxy-substituted azobenzene (mAzo) and β-cyclodextrin (β-CD) modified mesoporous silica nanoparticles (MSNs-CD).

Oral delivery of Bacillus subtilis spores expressing grass carp reovirus VP4 protein produces protection against grass carp reovirus infection

Grass carp (Ctenopharyngodon idellus) hemorrhagic disease (GCHD), caused by grass carp reovirus (GCRV), has given rise to an enormous loss in grass carp industry during the past years. Up to date, vaccination remained to be the most effective way to protect grass carp from GCHD. Oral vaccination is of major interest due to its advantages of noninvasive, time-saving, and easily-operated. The introduction of oral vaccination has profound impact on aquaculture industry because of its feasibility of extensive application for fish in various size and age. However, the main challenge in developing oral vaccine is that antigens are easily degraded and are easy to induce tolerance. Bacillus subtilis (B. subtilis) spores would be an ideal oral vaccine delivery system for their robust specialty, gene operability, safety and adjuvant property. VP4 protein is the major outer capsid protein encoded by GCRV segment 6 (S6), which plays an important role in viral invasion and replication. In this study, we used B. subtilis spores as the oral delivery system and successfully constructed the B. subtilis CotC-VP4 recombinant spores (CotC-VP4 spores) to evaluate its protective efficacy in grass carp. Grass carp orally immunized with CotC-VP4 spores showed a survival rate of 57% and the relative percent survival (RPS) of 47% after the viral challenge. Further, the specific IgM levels in serum and the specific IgZ levels in intestinal mucus were significantly higher in the CotC-VP4 group than those in the Naive group. The immune-related genes including three innate immune-related genes (IL-4/13A, IL-4/13B, CSF1R), four adaptive immune-related genes (BAFF, CD4L, MHC-II, CD8), three inflammation-related genes (IL-1β, TNF-α, TGF-β) and interferon type I (IFN-I) related signaling pathway genes were significantly up-regulated in the CotC-VP4 group. The study demonstrated that the CotC-VP4 spores produced protection in grass carp against GCRV infection, and triggered both innate and adaptive immunity post oral immunization. This work highlighted that Bacillus subtilis spores were powerful platforms for oral vaccine delivery, and the combination of Bacillus subtilis spores with GCRV VP4 protein was a promising oral vaccine.

Light-Responsive Janus-Particle-Based Coatings for Cell Capture and Release

A robust light-responsive coating based on Janus composite particles is achieved. First, strawberry-like silica Janus particles are synthesized by the sol-gel process at a patchy emulsion interface. One side of the silica Janus particles possesses nanoscale roughness, and the other side is flat. Then, spiropyran-containing polymer brushes are grafted onto the coarse hemispherical side of the as-synthesized Janus particles, and the other flat side is modified with imidazoline groups. The light-responsive polymer brush-terminated coarse hemispherical sides direct toward the air when the Janus composite particles self-organize into a layer on the surface of epoxy resin substrate. The imidazoline groups react with the epoxy groups in the epoxy resin to form a robust smart coating. The coating can be reversibly triggered between hydrophobic and hydrophilic by UV and visible-light irradiation, which is attributed to the isomerization of spiropyran moieties. When the hydrophobic ring-closed spiropyran form is prominent, HeLa cells can be effectively captured onto the coating. After UV light irradiation, the ring-closed spiropyran form changes to the hydrophilic ring-opened zwitterionic merocyanine form, and then the captured cells are released. This work shows promising potential for engineering advanced smart biointerfaces.

Visible-light-responsive polymeric multilayers for trapping and release of cargoes via host–guest interactions

Visible-light-responsive layer-by-layer assembled polyelectrolyte multilayers are fabricated for reversible trapping and release of cargoes via azobenzene/cyclodextrin host–guest interactions.

Photo, pH and redox multi-responsive nanogels for drug delivery and fluorescence cell imaging

A light, pH and redox triple-responsive spiropyran-based nanogel is prepared and applied for the efficient delivery of anticancer drugs and fluorescence cell imaging for the strong emission of merocyanine photoisomers.

Light-Triggered Specific Cancer Cell Release from Cyclodextrin/Azobenzene and Aptamer-Modified Substrate

Cell adhesion behaviors of stimuli-responsive surfaces have attracted significant attention for their potential biomedical applications. Distinct from temperature and pH stimuli, photoswitching avoids the extra input of thermal energy or chemicals. Herein, we designed a novel reusable cyclodextrin (CD)-modified surface to realize photoswitched specific cell release utilizing host-guest interactions between CD and azobenzene. The azobenzene-grafted specific cell capture agent was assembled onto the CD-modified surface to form a smart surface controlling cell adhesion by light radiation. After UV light irradiation, the azobenzene switched from trans- to cis-isomers, and the cis-azobenzene was not recognized by CD due to the unmatched host-guest pairs; thus, the captured MCF-7 cells could be released. Light-triggered specific cancer cell release with high efficiency may afford a smart surface with significant potential applications for the isolation and analysis of circulating tumor cells.

Photoswitched Cell Adhesion on Azobenzene-Containing Self-Assembled Films

Stimuli-responsive surfaces that can regulate and control cell adhesion have attracted much attention for their great potential in diverse biomedical applications. Unlike for pH- and temperature-responsive surfaces, the process of photoswitching requires no additional input of chemicals or thermal energy. In this work, two different photoresponsive azobenzene films are synthesized by chemisorption and electrostatic layer-by-layer (LbL) assembly techniques. The LbL film exhibits a relatively loose packing of azobenzene chromophores compared with the chemisorbed film. The changes in trans/cis isomer ratio of the azobenzene moiety and the corresponding wettability of the LbL films are larger than those of the chemisorbed films under UV light irradiation. The tendency for cell adhesion on the LbL films decreases markedly after UV light irradiation, whereas adhesion on the chemisorbed films decreases only slightly, because the azobenzene chromophores stay densely packed. Interestingly, the tendency for cell adhesion can be considerably increased on rough substrates, the roughness being introduced by use of photolithography and inductively coupled plasma deep etching techniques. For the chemisorbed films on rough substrates, the amount of cells that adhere also changes slightly after UV light irradiation, whereas, the amount of cells that adhere to LbL films on rough substrates decreases significantly.

Adsorption kinetic process of thiol ligands on gold nanocrystals

Understanding the kinetic mechanism during ligand adsorption on gold nanocrystals is important for designing and fine-tuning their properties and implications. Here, we report a kinetic study on the adsorption process of dodecanethiol ligands on Au nanocrystals of 3.3 nm by an in situ time-resolved X-ray absorption fine structure technique. A two-step process of dodecanethiol adsorption on Au NC surfaces is proposed based on the obtained ligand coverage, which shows a quick increase from 0 to 0.40 within the first 20 min, followed by a much slower increase to the limiting value of 0.94. In-depth analysis suggests that the first stage involves the quick adsorption of dodecanethiol to the corner and edge sites of Au NCs surfaces, leading to remarkable surface Au-Au bond length relaxation (from 2.79 to 2.81 Å) and pronounced gold-to-ligand charge transfer. The second step that corresponds to the much slower adsorption process to the surface facets could be described by the Langmuir kinetics equation with an adsorption rate constant of 0.0132 min(-1) and an initial coverage of 0.41, in good agreement with the initially preferable adsorption of thiols to the most favorable sites.

Expression of K6W-ubiquitin in lens epithelial cells leads to upregulation of a broad spectrum of molecular chaperones

PURPOSE

Accumulation and precipitation of abnormal proteins are associated with many age-related diseases. The ubiquitin-proteasome pathway (UPP) is one of the protein quality control mechanisms that selectively degrade damaged or obsolete proteins. The other arm of the protein quality control mechanism is molecular chaperones, which bind to and help refold unfolded or misfolded proteins. We previously showed that the molecular chaperones and the UPP work in a competitive manner in eliminating the denatured proteins. To further investigate the interaction between the two protein quality control mechanisms, we determined the effects of the impairment of the UPP on the expression of molecular chaperones in human lens epithelial cells (HLEC).

METHODS

K6W-ubiquitin, a dominant negative inhibitor of the UPP, was expressed in confluent HLEC via an adenoviral vector. The mRNA levels of cytoplasmic and endoplasmic reticulum (ER) chaperones were determined by real-time reverse transcription polymerase chain reaction (RT-PCR). Protein levels for these chaperones were determined by western blotting.

RESULTS

Expression of K6W-ubiquitin in HLEC increased the expression of a broad spectrum of molecular chaperones. Among the heat-shock proteins, mRNA for alphaB-crystallin, Hsp70, and Hsp90 increased 27 fold, 21 fold, and twofold, respectively, in response to K6W-ubiquitin expression. Among the ER chaperones and ER stress related factors, mRNA levels of protein disulfide isomerase, Grp75, Grp78, Grp94, and the CAAT/enhancer binding protein homologous protein (CHOP) increased from 1.7 fold to 3.7 fold. The mRNA for Hsp60 also increased 1.6 fold in response to the expression of K6W-ubiquitin. The expression pattern of these chaperones in response to the expression of K6W ubiquitin is similar to that obtained when cells were treated with proteasome inhibitors or heat-shock.

CONCLUSIONS

It appears that the upregulation of these chaperones is related to the elevated levels of abnormal proteins in the cells. These findings support our hypothesis that the molecular chaperones and the UPP may back each other up in the process of protein quality control. The upregulation of molecular chaperones in response to the expression of a dominant negative ubiquitin may compensate for the impairment of the UPP in the degradation of abnormal proteins.

Study on the relation between occupational fenvalerate exposure and spermatozoa DNA damage of pesticide factory workers

AIMS

To determine sperm nuclear DNA integrity and to investigate the relation between fenvalerate (FE) exposure and spermatozoa DNA damage.

METHODS

Sperm DNA fragmentation was detected by a modified alkaline single cell gel electrophoresis (Comet) assay and a terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL) assay. The olive tail moment (OTM) and percentage tail DNA were measured by the Comet assay, and cell positive percentage was measured by the TUNEL assay for DNA damage evaluation.

RESULTS

The DNA integrity of spermatozoa of external and internal control groups were both significantly greater than that of the FE exposed group. The median value of tail DNA percentage in the exposure group was 11.30, which was significantly higher than 5.60 in the internal control group and 5.10 in the external control group. The median value of OTM was 3.80 in the exposure group, significantly higher than 1.50 in the internal control group and 2.00 in the external control group. Mean cell positive was 31.2% in the exposure group, significantly higher than 17.4% in the internal control and 19.6% in the external control groups. Cell positive (%) was significantly correlated with tail DNA percentage and with OTM of whole subjects (n = 63).

CONCLUSIONS

Results showed that occupational FE exposure is associated with an increase in sperm DNA damage. A combination of the Comet and TUNEL assays would offer more comprehensive information for a better understanding of sperm DNA damage, and the biological significance of sperm DNA damage in sperm function and male infertility.

Local structure evolution of FexNi77-xCu(1-)Nb2P14B6 soft magnetic materials by mechanical alloying

Mechanically alloyed Fe(x)Ni77-xCu1Nb2P14B6 soft magnetic materials have been prepared with different atomic compositions. The alloy structures are investigated by X-ray absorption fine structure (XAFS). The results show that mechanical alloying (MA) can drive the Fe(x)Ni77-xCu1Nb2P14B6 powder mixture to produce amorphous alloy while the atomic concentration of Fe element is about and over 40%. On the contrary, the MA Fe(x)Ni77 xCu1Nb2P14B6 is a solid solution with a fcc-like structure in the region of lower Fe atomic concentration (<22%), preserving a medium-range order around Ni and Fe atoms. Moreover, we have found that the local structure geometry of Fe atom is similar to that of Ni atom for all the MA Fe(x)Ni77-xCu1NbP14B6 samples. It indicates that the local structures of Fe and Ni atoms in a Fe(x)Ni77-xCu1Nb2P14B6 sample only depend on the x value of element Ni after ball milling.

[Direct determination of rare earth elements in rare earth chloride and light rare earth oxide by ICP-AES]

ICP-AES was used for the direct determination of 15 rare earth elements in synthetic solutions and real sample. Spectral interferences between REEs in the mixtures of rare earth were investigated with a high-resolution echelle spectrometer and suitable analytical lines of 15 rare earth elements were selected. The Multicomponent Spectral Fitting(MSF) models were made. The method was used to remove spectral interferences and background. The factors influence the modes were discussed. The influences of acidity and ICP parameters were investigated. The compromise condition of simultaneous determination of 15 REEs was selected. Axially viewed ICP torch was used to determine 15 REEs, The detection limits are Y 0.21 microgram.L-1, La 9.1 micrograms.L-1, Ce 14.1 micrograms.L-1, Pr 1.9 micrograms.L-1, Nd 7.8 micrograms.L-1, Tm 0.37 microgram.L-1, Yb 0.12, Lu microgram.L-1, Ho 0.06 microgram.L-1, Er 0.06 microgram.L-1, Tb 0.53 microgram.L-1, Sm 1.14 micrograms.L-1, Eu 0.09 microgram.L-1, Dy 0.08 microgram.L-1, Gd 0.30 microgram.L-1. The recoveries of this procedure are between 98.4% and 101.7%. The RSD is within 2%. The method is rapid and accuracy.

Capability of serum to convert streptomycin to cytotoxin in patients with aminoglycoside-induced hearing loss

Individual variations in sensitivity to the ototoxic effects of aminoglycoside antibiotics are well documented. Our research demonstrates that there is an apparent difference in serum from patients who are resistant or susceptible to aminoglycoside ototoxicity. In the first study, the cytotoxicity of sera from patients with and without hearing loss after various time periods following the discontinuation of aminoglycoside treatment was assayed using the isolated outer hair cell toxicity assay. The results indicate that sera from patients with hearing loss were significantly more toxic than sera from patients with normal hearing or minimal hearing loss. This toxicity may persist for up to 1 year after discontinuation of aminoglycoside therapy. In a second study, sera were obtained from patients who had received aminoglycoside therapy several years previously. None of these sera was toxic to isolated outer hair cells in vitro. Streptomycin was then incubated with the sera or a protein fraction isolated from sera, and the incubation mixtures were tested for toxicity. The percentage of damaged outer hair cells was significantly higher when streptomycin had been treated with sera or a serum protein fraction from patients with hearing loss (58+/-10% and 68+/-9%, respectively) than with sera or a serum protein fraction from a control group (10+/-5% and 17+/-4%, respectively). In addition, several incubation mixtures were analyzed using high performance liquid chromatography. A new chromatographic peak was only found in the incubations of streptomycin with serum protein from patients with hearing loss. The results suggest that sera from individuals sensitive to aminoglycoside antibiotics may metabolize these drugs to cytotoxins.