Bacterial-derived Neutrophilic Inflammation Drives Lung Remodeling in a Mouse Model of Chronic Obstructive Pulmonary Disease.

Loss of secretory IgA is common in the small airways of patients with chronic obstructive pulmonary disease and may contribute to disease pathogenesis. Using mice that lack secretory IgA in the airways due to genetic deficiency of polymeric Ig receptor (pIgR-/- mice), we investigated the role of neutrophils in driving the fibrotic small airway wall remodeling and emphysema that develops spontaneously in these mice. By flow cytometry, we found an increase in the percentage of neutrophils among CD45+ cells in the lungs, as well as an increase in total neutrophils, in pIgR-/- mice compared with wild-type controls. This increase in neutrophils in pIgR-/- mice was associated with elastin degradation in the alveolar compartment and around small airways, along with increased collagen deposition in small airway walls. Neutrophil depletion using anti-Ly6G antibodies or treatment with broad-spectrum antibiotics inhibited development of both emphysema and small airway remodeling, suggesting that airway bacteria provide the stimulus for deleterious neutrophilic inflammation in this model. Exogenous bacterial challenge using lysates prepared from pathogenic and nonpathogenic bacteria worsened neutrophilic inflammation and lung remodeling in pIgR-/- mice. This phenotype was abrogated by antiinflammatory therapy with roflumilast. Together, these studies support the concept that disruption of the mucosal immune barrier in small airways contributes to chronic obstructive pulmonary disease progression by allowing bacteria to stimulate chronic neutrophilic inflammation, which, in turn, drives progressive airway wall fibrosis and emphysematous changes in the lung parenchyma.

Leptogenic effects of NAPE require activity of NAPE-hydrolyzing phospholipase D.

Food intake induces synthesis of N-acylphosphatidylethanolamines (NAPEs) in the intestinal tract. While NAPEs exert leptin-like (leptogenic) effects, including reduced weight gain and food intake, the mechanisms by which NAPEs induce these leptogenic effects remain unclear. One key question is whether intestinal NAPEs act directly on cognate receptors or first require conversion to N-acylethanolamides (NAEs) by NAPE-hydrolyzing phospholipase D (NAPE-PLD). Previous studies using Nape-pld-/- mice were equivocal because intraperitoneal injection of NAPEs led to nonspecific aversive effects. To avoid the aversive effects of injection, we delivered NAPEs and NAEs intestinally using gut bacteria synthesizing these compounds. Unlike in wild-type mice, increasing intestinal levels of NAPE using NAPE-synthesizing bacteria in Nape-pld-/- mice failed to reduce food intake and weight gain or alter gene expression. In contrast, increasing intestinal NAE levels in Nape-pld-/- mice using NAE-synthesizing bacteria induced all of these effects. These NAE-synthesizing bacteria also markedly increased NAE levels and decreased inflammatory gene expression in omental adipose tissue. These results demonstrate that intestinal NAPEs require conversion to NAEs by the action of NAPE-PLD to exert their various leptogenic effects, so that the reduced intestinal NAPE-PLD activity found in obese subjects may directly contribute to excess food intake and obesity.

Comparative Transcriptome and DNA methylation analyses of the molecular mechanisms underlying skin color variations in Crucian carp (Carassius carassius L.).

BACKGROUND: Crucian carp is a popular ornamental strain in Asia with variants in body color. To further explore the genetic mechanisms underlying gray and red body color formation in crucian carp, the skin transcriptomes and partial DNA methylation sites were obtained from red crucian carp (RCC) and white crucian carp (WCC). Here, we show significant differences in mRNA expression and DNA methylation sites between skin tissues of RCC and WCC. RESULTS: Totals of 3434 and 3683 unigenes had significantly lower and higher expression in WCC, respectively, compared with unigenes expressed in RCC. Some potential genes for body color development were further identified by quantitative polymerase chain reaction, such as mitfa, tyr, tyrp1, and dct, which were down-regulated, and foxd3, hpda, ptps, and gch1, which were up-regulated. A KEGG pathway analysis indicated that the differentially expressed genes were mainly related to mitogen activated protein kinase (MAPK), Wnt, cell cycle, and endocytosis signaling pathways, as well as variations in melanogenesis in crucian carp. In addition, some differentially expressed DNA methylation site genes were related to pigmentation, including mitfa, tyr, dct, foxd3, and hpda. The differentially expressed DNA methylation sites were mainly involved in signaling pathways, including MAPK, cAMP, endocytosis, melanogenesis, and Hippo. CONCLUSIONS: Our study provides the results of comparative transcriptome and DNA methylation analyses between RCC and WCC skin tissues and reveals that the molecular mechanism of body color variation in crucian carp is strongly related to disruptions in gene expression and DNA methylation during pigmentation.

Comparative transcriptome analysis of molecular mechanism underlying gray-to-red body color formation in red crucian carp (Carassius auratus, red var.).

Red crucian carp (Carassius auratus red var.) is an ornamental fish with vivid red/orange color. It has been found that the adult body color of this strain forms a gray-to-red change. In this study, skin transcriptomes of red crucian carp are first obtained for three different stages of body color development, named by gray-color (GC), color-variation (CV), and red-color (RC) stages, respectively. From the skins of GC, CV, and RC, 103,229; 108,208; and 120,184 transcripts have been identified, respectively. Bioinformatics analysis reveals that 2483, 2967, and 4473 unigenes are differentially expressed between CV and GC, RC and CV, and RC and GC, respectively. A part of the differentially expressed genes (DEGs) are involved in the signaling pathway of pigment synthesis, such as the melanogenesis genes (Mitfa, Pax3a, Foxd3, Mc1r, Asip); tyrosine metabolism genes (Tyr, Dct, Tyrp1, Silva, Tat, Hpda); and pteridine metabolism genes (Gch, Xdh, Ptps, Tc). According to the data of transcriptome and quantitative PCR, the expression of Mitfa and its regulated genes which include the genes of Tyr, Tyrp1, Dct, Tfe3a, and Baxα, decreases with gray-to-red change. It is suggested that Mitfa and some genes, being related to melanin synthesis or melanophore development, are closely related to the gray-to-red body color transformation in the red crucian carp. Furthermore, the DEGs of cell apoptosis and autophagy pathway, such as Tfe3a, Baxα, Hsp70, Beclin1, Lc3, Atg9a, and Atg4a, might be involved in the melanocytes fade away of juvenile fish. These results shed light on the regulation mechanism of gray-to-red body color transformation in red crucian carp, and are helpful to the selective breeding of ornamental fish strains.

Salinomycin radiosensitizes human nasopharyngeal carcinoma cell line CNE-2 to radiation.

Nasopharyngeal carcinoma (NPC) is primarily treated by chemoradiation. However, how to promote radiation sensitivity in NPC remains a challenge. Salinomycin is potentially useful for the treatment of cancer. This study aimed to explore the radiosensitivity of salinomycin on human nasopharyngeal carcinoma cell line CNE-2. CNE-2 were treated with salinomycin or irradiation, alone or in combination. The cytotoxicity effects of salinomycin were measured using CCK-8 assay. Clonogenic survival assay was used to evaluate the effects of salinomycin on the radiosensitivity of CNE-2. The changes of cell cycle distribution and apoptosis were assayed using flow cytometry. The expression of Caspase3/Bax/Bal-2 was detected by Western blotting. DNA damage was detected via γ-H2AX foci counting. The results showed that salinomycin induced apoptosis and G2/M arrest, increased Bax and cleaved Caspase3, decreased Bcl-2 expression, and increased the formation of γ-H2AX nuclear foci. These data suggest that salinomycin may be a radiosensitizer for NPC radiotherapy.

Two new species of ant-loving beetles (Coleoptera: Staphylinidae: Pselaphinae) from Jiulong National Wetland Park, China.

Continued collecting efforts at the Jiulong National Wetland Park, Zhejiang, East China revealed two additional species of the ant-loving beetle subfamily Pselaphinae (Coleoptera: Staphylinidae): Trisiniotus jiulong sp. nov. and Arthromelodes lianghongbini sp. nov. Both new species are diagnosed, described, and their important characters are illustrated.

Design and Experimental Study of an Improved Pressure Core Sampler for Marine Gas Hydrates.

A pressure core sampler (PCS) is considered an effective tool to retrieve marine gas hydrate cores from hydrate-bearing sediments. However, according to the sampling application statistics, the success rate of pressure coring changed from 30% to 85% in different drilling wells. Such severe fluctuation will cause huge uncertainty in the practical application of technology and economic benefits. Herein, we present a new PCS designed to improve pressure-retaining reliability. The work principle, design and calculations, and structure composition were described. Through the laboratory tests and drilling experiments, the maximum holding pressure in the pressure chamber was 32.1 MPa, and the pressure loss rates of holding pressure after 2 h changed from 1.96% to 2.46%. The maximum temperature-rising value in the pressure chamber was 0.96 °C under a temperature of 23.5 °C in 2 h. Furthermore, the success rate of the pressure core reached 87.5% and the core recovery was not less than 80%, which were verified by 8 pressure core runs in three different offshore wells. Therefore, we conclude that this new and improved PCS has great application value in gas hydrate exploration that seeks to recover more accurate cores in situ, especially in the silt and sand layers.

FTIR determination of the degree of molar substitution for hydroxypropyl chitosan.

We developed and validated a novel Fourier transform infrared (FTIR) method to determine the degree of molar substitution (MS) for hydroxypropyl chitosan (HPCS) using nuclear magnetic resonance (1H NMR) as a reference, and investigated the factors influencing the MS assay. Through extensive screening of integration methods for candidate bands in the FTIR spectrum of HPCS using 20 HPCS samples with degrees of acetylation (DA) ranging from 0.003 to 0.139, we found that when using band area at 2970 cm-1 as a probe integral, the MS values obtained via the 1H NMR method exhibited linear correlations (R2 > 0.98) with at least 16 integral ratios derived from their FTIR spectra. The optimal reference bands with high reliability are located at 3440 cm-1 and 1415 cm-1, with R2 exceeding 0.99 and a MS range of 0.17-1.92. The band at 2875 cm-1 is less affected by the trace moisture present in HPCS samples than the others. The results of the method validation demonstrated a mean recovery of 98.9 ± 2.8 % and an RSD below 10 %, suggesting a simple, robust, and highly accurate and precise method. This method could be extendable for the determination of the MS of insoluble HPCS derivatives and other hydroxypropylated polysaccharides.

Isolevuglandin-modified phosphatidylethanolamine is metabolized by NAPE-hydrolyzing phospholipase D.

Lipid aldehydes including isolevuglandins (IsoLGs) and 4-hydroxynonenal modify phosphatidylethanolamine (PE) to form proinflammatory and cytotoxic adducts. Therefore, cells may have evolved mechanisms to degrade and prevent accumulation of these potentially harmful compounds. To test if cells could degrade isolevuglandin-modified phosphatidylethanolamine (IsoLG-PE), we generated IsoLG-PE in human embryonic kidney 293 (HEK293) cells and human umbilical cord endothelial cells and measured its stability over time. We found that IsoLG-PE levels decreased more than 75% after 6 h, suggesting that IsoLG-PE was indeed degraded. Because N-acyl phosphatidylethanolamine-hydrolyzing phospholipase D (NAPE-PLD) has been described as a key enzyme in the hydrolysis of N-acyl phosphatidylethanoamine (NAPE) and both NAPE and IsoLG-PE have large aliphatic headgroups, we considered the possibility that this enzyme might also hydrolyze IsoLG-PE. We found that knockdown of NAPE-PLD expression using small interfering RNA (siRNA) significantly increased the persistence of IsoLG-PE in HEK293 cells. IsoLG-PE competed with NAPE for hydrolysis by recombinant mouse NAPE-PLD, with the catalytic efficiency (V(max)/K(m)) for hydrolysis of IsoLG-PE being 30% of that for hydrolysis of NAPE. LC-MS/MS analysis confirmed that recombinant NAPE-PLD hydrolyzed IsoLG-PE to IsoLG-ethanolamine. These results demonstrate that NAPE-PLD contributes to the degradation of IsoLG-PE and suggest that a major physiological role of NAPE-PLD may be to degrade aldehyde-modified PE, thereby preventing the accumulation of these harmful compounds.

Polarization flipping and hysteresis phenomenon in laser with optical feedback.

We realize polarization control in He-Ne laser by optical feedback. Polarization flipping occurs when the length of the anisotropy feedback cavity is modulated. The relationship between polarization flipping and phase retardation of birefringence component placed in feedback cavity is built. The hysteresis effect of polarization flipping is observed. We build a system to measure the size of hysteresis loop based on Laser Feedback Interferometer (LFI). The variation of hysteresis loop with phase retardation is measured. The width of hysteresis loop decreases when phase retardation increases.

A new species of Tyrodes Raffray (Coleoptera: Staphylinidae: Pselaphinae) from China.

A new species of the small pselaphine genus Tyrodes Raffray (Pselaphitae: Tyrini), T. tibialis sp. nov., is described and illustrated from Guangxi, southwestern China. This species can be separated from its congeners mainly by the aedeagal characters as well as by the modified sternite 2 (V), and presence of a preapical projection of the metatibiae.

The genus Pseudophanias Raffray (Coleoptera, Staphylinidae, Pselaphinae) from Nanling Priority Area for Biodiversity Conservation, China.

Prior to this study, no species of Pseudophanias Raffray had been reported from Nanling, a vast biodiversity conservation area that spans five provinces in southern China. In this paper, three new species of the genus are described: Pseudophaniasfurcilobussp. nov. (Guizhou, Guangxi), P.leigongsp. nov. (Guizhou), and P.mulunsp. nov. (Guangxi), suggesting that additional study on the diversity of this group in the area is required. These species are characterized, keyed, and compared to similar congeners, supplemented with illustrations of the habitus and other morphological characters.

CAN: Context-assisted full Attention Network for brain tissue segmentation.

Brain tissue segmentation is of great value in diagnosing brain disorders. Three-dimensional (3D) and two-dimensional (2D) segmentation methods for brain Magnetic Resonance Imaging (MRI) suffer from high time complexity and low segmentation accuracy, respectively. To address these two issues, we propose a Context-assisted full Attention Network (CAN) for brain MRI segmentation by integrating 2D and 3D data of MRI. Different from the fully symmetric structure U-Net, the CAN takes the current 2D slice, its 3D contextual skull slices and 3D contextual brain slices as the input, which are further encoded by the DenseNet and decoded by our constructed full attention network. We have validated the effectiveness of the CAN on our collected dataset PWML and two public datasets dHCP2017 and MALC2012. Our code is available at https://github.com/nwuAI/CAN.

Nomogram to predict unfavorable outcome of endovascular thrombectomy for large ischemic core.

OBJECTIVE: The prognosis for patients presenting with a large ischemic core (LIC) following endovascular thrombectomy is relatively poor. This study aimed to construct and validate a nomogram for predicting 3-month unfavorable outcome in patients with anterior circulation occlusion-related LIC who underwent endovascular thrombectomy. METHODS: A retrospective training cohort and a prospective validation cohort of patients with a large ischemic core were studied. The diffusion weighted imaging related radiomic features and pre-thrombectomy clinical features were collected. After the selection of relevant features, a nomogram predicting modified Rankin Scale score of 3-6 as an unfavorable outcome was established. The discriminatory value of the nomogram was evaluated with a receiver operating characteristic curve. RESULTS: A total of 140 patients (mean age 66.3 ± 13.4 years, 35% female) were included in this study, consisting of a training cohort (n = 95) and a validation cohort (n = 45). The percentage of patients with an mRS scores of 0-2 was 30%, 0-3 was 40.7%, and 32.9% were dead. Age, National Institute of Health Stroke Scale (NIHSS) score, and two radiomic features, Maximum2DDiameterColumn and Maximum2DDiameterSlice, were identified as factors associated with unfavorable outcome in the nomogram. The nomogram demonstrated an area under the curve of 0.892 (95% confidence interval [CI], 0.812-0.947) in the training dataset and 0.872 (95% CI, 0.739-0.953) in the validation dataset. INTERPRETATION: This nomogram, which includes age, NIHSS score, Maximum2DDiameterColumn, and Maximum2DDiameterSlice, may predict the risk of unfavorable outcome in patients with LIC caused by anterior circulation occlusion.

ErbB2 and ErbB3 regulate recovery from dextran sulfate sodium-induced colitis by promoting mouse colon epithelial cell survival.

ErbB2 and ErbB3 receptor tyrosine kinases are key regulators of proliferation, migration, differentiation and cell survival; however, their roles in gastrointestinal biology remain poorly defined. We hypothesized that ErbB2 and ErbB3 promote colon epithelial cell survival in the context of the wound-healing response following colitis. In this study, mice bearing intestinal epithelial-specific deletion of ErbB2 or ErbB3 were treated with dextran sulfate sodium (DSS). Colon sections were examined for injury, cytokine expression, epithelial cell proliferation and apoptosis. Deletion of epithelial ErbB2 did not affect the extent of intestinal injury in response to DSS, whereas deletion of ErbB3 slightly increased injury. However, the roles of both receptors were more apparent during recovery from DSS colitis, in which ErbB2 or ErbB3 epithelial deletion resulted in greater inflammation and crypt damage during the early reparative period. Moreover, loss of ErbB3 prevented normal epithelial regeneration in the long term, with damage persisting for at least 6 weeks following a single round of DSS. Delayed recovery in mice with epithelial deletion of ErbB2 or ErbB3 was associated with increased colonic expression of tumor necrosis factor alpha and increased epithelial apoptosis. Furthermore, epithelial ErbB3 deletion increased apoptosis at baseline and during DSS injury. Additionally, epithelial cell hyperproliferation during recovery was exacerbated by deletion of either ErbB2 or ErbB3. These results suggest that ErbB2 and ErbB3 have important cytoprotective and reparative roles in the colonic epithelium following injury, by promoting colon epithelial cell survival.

[Aitongxiao recipe regulated survivin and Bcl- 2 in rats' transplanted hepatoma carcinoma cell].

OBJECTIVE: To study the main mechanisms of Aitongxiao Recipe (ATXR) for anti-tumor at the molecular level, and to clarify different efficient drugs' roles in anti-tumor, thus in-depth explaining the objectivity and substance of "cancer toxic" theory. METHODS: Walker-256 tumor strain was used for Wistar rat transplanted liver cancer modeling. After successful modeling rats were randomly divided into 5 groups, i. e., the ATXP group, the qi regulating and blood circulating group (as the assembled I group), the heat clearing and detoxification group (as the assembled II group), the body resistance strengthening and cultivating group (as the assembled III group), and the model group, 10 in each group. Corresponding medication was given to rats in each group for 14 successive days. Finally rats were sacrificed and the tumor mass was taken out. The apoptosis rate and the cell cycle of tumor cells were detected by flow cytometry Annexin V/PI. The protein and mRNA expressions of Bcl-2 and survivin were detected using immunohistochemistry and real-time fluorescent quantitative PCR. RESULTS: (1) The apoptosis of hepatoma carcinoma cells could be obviously promoted in the ATXP group. The cell cycle could also be affected, making major cells arrest at G0/G1 phase. The proliferation of hepatoma carcinoma cells was effectively prevented. The efficacy in the assembled II group was in line with that in the ATXP group with no statistical difference (P>0.05). It was also effective in the assembled III group, but its efficacy was not as good as that in the former two groups, showing statistical difference (P<0.01). (2) ATXP could obviously down-regulate the protein and mRNA expressions of Bcl-2 and survivin in hepatoma carcinoma cells. Drugs for heat clearing and detoxification showed significant effects on down-regulating the protein and mRNA expressions of Bcl-2 and survivin in hepatoma carcinoma cells. Their effects were similar to that of ATXP (P>0.05). The effects of drugs for body resistance strengthening and cultivating were not as good as the former two, showing statistical difference (P<0.01). Drugs for blood circulating and stasis removing could up-regulate the protein and mRNA expressions of Bcl-2 and survivin to some extent. CONCLUSIONS: (1) ATXP could increase the apoptosis ratio of hepatoma carcinoma cells obviously through down-regulating the protein and mRNA expressions of Bcl-2 and survivin, thus inhibiting their proliferation. (2) Drugs for heat clearing and detoxification played the most important roles in ATXP. The evil heat and dampness (damp-heat insidious pathogen) is the most fundamental carcinogenic factors. The insufficiency of vital qi is also one of the pathogenic factors. The mechanisms of phlegm, stasis, and other pathological products are not clear and await further studies.

Attention-modulated multi-branch convolutional neural networks for neonatal brain tissue segmentation.

Accurate measurement of brain structures is essential for the evaluation of neonatal brain growth and development. The conventional methods use manual segmentation to measure brain tissues, which is very time-consuming and inefficient. Recent deep learning achieves excellent performance in computer vision, but it is still unsatisfactory for segmenting magnetic resonance images of neonatal brains because they are immature with unique attributes. In this paper, we propose a novel attention-modulated multi-branch convolutional neural network for neonatal brain tissue segmentation. The proposed network is built on the encoder-decoder framework by introducing both multi-scale convolutions in the encoding path and multi-branch attention modules in the decoding path. Multi-scale convolutions with different kernels are used to extract rich semantic features across large receptive fields in the encoding path. Multi-branch attention modules are used to capture abundant contextual information in the decoding path for segmenting brain tissues by fusing both local features and their corresponding global dependencies. Spatial attention connections between the encoding and decoding paths are designed to increase feature propagation for both avoiding information loss during downsampling and accelerating model training convergence. The proposed network was implemented in comparison with baseline methods on three neonatal brain datasets. Our network achieves the average Dice similarity coefficients/the average Hausdorff distances of 0.9116/8.1289, 0.9367/9.8212 and 0.8931/8.1612 on the customized dCBP2021 dataset, 0.8786/11.7863, 0.8965/13.4296 and 0.8539/10.462 on the public NBAtlas dataset, as well as 0.9253/7.7968, 0.9448/9.5472 and 0.9132/7.5877 on the public dHCP2017 dataset in partitioning the brain into gray matter, white matter and cerebrospinal fluid, respectively. The experimental results show that the proposed method achieves competitive state-of-the-art performance in neonatal brain tissue segmentation. The code and pre-trained models are available at https://github.com/zhangyongqin/AMCNN.

Cross-domain heterogeneous residual network for single image super-resolution.

Single image super-resolution is an ill-posed problem, whose purpose is to acquire a high-resolution image from its degraded observation. Existing deep learning-based methods are compromised on their performance and speed due to the heavy design (i.e., huge model size) of networks. In this paper, we propose a novel high-performance cross-domain heterogeneous residual network for super-resolved image reconstruction. Our network models heterogeneous residuals between different feature layers by hierarchical residual learning. In outer residual learning, dual-domain enhancement modules extract the frequency-domain information to reinforce the space-domain features of network mapping. In middle residual learning, wide-activated residual-in-residual dense blocks are constructed by concatenating the outputs from previous blocks as the inputs into all subsequent blocks for better parameter efficacy. In inner residual learning, wide-activated residual attention blocks are introduced to capture direction- and location-aware feature maps. The proposed method was evaluated on four benchmark datasets, indicating that it can construct the high-quality super-resolved images and achieve the state-of-the-art performance. Code and pre-trained models are available at https://github.com/zhangyongqin/HRN.

The validation of the standard Chinese version of the European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire 30 (EORTC QLQ-C30) in pre-operative patients with brain tumor in China.

BACKGROUND: Health related quality of life (HRQOL) has increasingly emphasized on cancer patients. The psychometric properties of the standard Chinese version of the European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire 30 (EORTC QLQ-C30, version 3.0) in brain tumor patients wasn't proven, and there was no baseline HRQOL in brain tumor patients prior to surgery. METHODS: The questionnaire EORTC QLQ-C30 (version 3.0) was administered at three time points: T1, the first or the second day that patients were hospitalized after the brain tumor suspected or diagnosed by MRI or CT; T2, 1 to 2 days after T1, (T1 and T2 were both before surgery); T3, the day before discharge. Clinical variables included disease histologic types, cognitive function, and Karnofsky Performance Status. RESULTS: Cronbach's alpha coefficients for multi-item scales were greater than .70 and multitrait scaling analysis showed that most of the item-scale correlation coefficients met the standards of convergent and discriminant validity, except for the cognitive functioning scale. All scales and items exhibited construct validity. Score changes over peri-operation were observed in physical and role functioning scales. Compared with mixed cancer patients assessed after surgery but before adjuvant treatment, brain tumor patients assessed pre-surgery presented better function and fewer symptoms. CONCLUSIONS: The standard Chinese version of the EORTC QLQ-C30 was overall a valid instrument to assess HRQOL in brain tumor patients in China. The baseline HRQOL in brain tumor patients pre-surgery was better than that in mixed cancer patients post-surgery. Future study should modify cognitive functioning scale and examine test-retest reliability and response validity.

Development and validation of an improved 3-methyl-2-benzothiazolinone hydrazone method for quantitative determination of reducing sugar ends in chitooligosaccharides.

An accurate and sensitive analytical method for detecting and quantifying reducing sugar ends (RSE) in chitooligosaccharides (COSs) is the key quality parameter for evaluating their structure-function relationship and potential applications. In this work, we develop and validate a novel colorimetric assay with high accuracy and precision for determining RSE content using 3-methyl-2-benzothiazolinone hydrazone (MBTH). Under optimal conditions, the stoichiometry is verified using mono-, di-, and tri- glucosamine hydrochlorides, and the dilution ratio does not interfere with the RSE content measured at 590 nm. The regression equation of glucosamine reveal a good linear relationship (R2 = 0.9999). The detection limit, quantification limit, mean relative standard deviation (RSD), and recovery are 2.28 µM, 9.11 µM, 1.90%, and 98.0%, respectively. The newly developed method is potentially useful for monitoring COS hydrolysis, number average molecular weight, and chitosanase activity.