The stereoselective pharmacokinetics of the desmethyl-phencynonate hydrochloride in beagle dogs.

The aim of this study was to investigate the chiral inversion and the stereoselective pharmacokinetic profiles of desmethyl-phencynonate hydrochloride after administration of the single isomer and its racemate to beagle dogs. A liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was established for determination of the stereoisomers on chiral columns in beagle dog plasma, which met all the requirements. The chiral inversion in dogs of the desmethyl-phencynonate hydrochloride were studied after administration of the single isomer or the racemic modification. The stereoselective pharmacokinetic profiles of the desmethyl-phencynonate hydrochloride were studied by assays for simultaneous isomers after administration of the racemic modification. The results showed that the absorption of the R-configuration dosed as the single isomer was higher than it dosed as the racemic modification. The AUC(0-t), AUC(0-∞), and Cmax of the S-configuration were much higher than those of R-configuration after oral administration of the racemic desmethyl-phencynonate hydrochloride. The chiral inversion of desmethyl-phencynonate isomers could not occur in dogs after administration of the R-configuration.

Analysis of the relationship between shorter sleep duration and wrist fractures: based on NHANES.

BACKGROUND: Wrist fracture is one of the common limb fractures. Its incidence rate increases with age and osteoporosis. Nowadays, Sleep health is increasingly valued, but the relationship between wrist fractures and sleep time is not yet clear. METHODS: Data in this study were collected and screened from the NHANES from 2005 to 2010 and 2013 to 2014. The variables were extracted from interviews and compared between the wrist fractures and the sleep duration. The data was analyzed by weighted multivariate logistic regression. RESULTS: After excluding individuals who were not eligible and had invalid data, we finally identified 1835 participants for inclusion in this study. We found a negative association between the sleep duration and the fractured of the wrist (OR = 1.027,95% CI (1.027, 1.028), P < 0.00001). CONCLUSION: This study demons that the association between the sleep duration and the fractures of the wrist is significant. Our findings provide a better understanding of the relationship between sleep duration and wrist fractures. This study may help us reducing the incidence of wrist fractures in the population based on healthy sleep management in the future, and improve the quality of life of middle-aged and elderly patients. Provide evidence for clinical patients to manage healthy sleep.

The Analysis of Serum Klotho Protein Level and Related Gene Polymorphism in Osteoporotic Fracture of Elderly Patients with Osteoporosis.

Objective: Klotho protein level are reported to play important roles in the osteoporosis. To investigate the correlation between serum Klotho protein level and related gene (Klotho G395-A gene) polymorphism and osteoporotic fracture in elderly patients with osteoporosis. Methods: A total of 62 elderly patients with osteoporosis admitted to the Department of Orthopedics of our hospital from January 2021 to June 2022 were included in the study group. Another 62 elderly patients without osteoporosis who underwent a physical examination at the same time were selected as the control group. Patients in the study group were divided into group A (n = 23, osteoporotic fracture) and group B (n = 39, osteoporotic fracture) according to the occurrence of osteoporotic fracture. Serum Klotho protein level was detected in all patients, and its related gene (Klotho G395-A gene) polymorphism was analyzed. After fasting in the morning (fasting for more than 8 hours), 3-5 ml venous blood was collected and immediately placed in a centrifuge tube. Serum was separated and serum Klotho protein level was measured by enzyme-linked immunosorbent assay kit. Polymorphism typing was performed by Taqman allele-specific hybridization analysis. At the same time, general information (gender, age, body mass index, systolic blood pressure, diastolic blood pressure, glycated glucose protein, low-density lipoprotein cholesterol, bone mineral density) was collected. The differences in general data, serum Klotho protein level and Klotho G395-A gene polymorphism between the study group and the control group were analyzed. Spearman analysis was used to analyze the correlation between general data, serum Klotho protein level and Klotho G395-A gene and osteoporotic fracture. Logistic analysis was used to analyze the independent risk factors of osteoporotic fracture. Results: There was no significant difference of the sex, systolic blood pressure (SBP), diastolic blood pressure (DBP), Klotho G395-A genotype GG and alleles A and G between the study group and the control group. There was significant difference of body mass index (BMI), glycated glucose protein, low-density lipoprotein cholesterol (LDL-C), bone mineral density, serum Klotho protein level and Klotho G395-A genotype AA and AG were between the study group and the control group. Gender, age, glycated glucose protein and Klotho G395-A genotype AA were positively correlated with osteoporotic fracture (P < .05), while bone mineral density was negatively correlated with osteoporotic fracture (P < .05). There was no correlationship between the serum Klotho protein level and the incidence of osteoporotic fracture (P > .05). Logistic analysis showed that age, bone mineral density and Klotho G395-A genotype AA were independent risk factors for osteoporotic fracture. Conclusion: The level of serum Klotho protein and related gene polymorphisms are both related to osteoporotic fracture in elderly patients with osteoporosis. It is significant to reduce the incidence of osteoporotic fractures. In future, more experiments are needed to explore the underlying mechanism.

Glycan Mapping of Low-Molecular-Weight Heparin Using Mass Spectral Correction Based on Chromatography Fitting with "Glycomapping" Software.

In this work, the first version of "Glycomapping" software is developed for the analysis of the most common low-molecular-weight heparin (LMWH), enoxaparin. Using ultrahigh-performance liquid chromatography-mass spectrometry, size exclusion chromatography is applied, and a virtual database of glycans in enoxaparin is established for the initial searching. With "Glycomapping", a complex chromatogram can be fitted, significantly improving resolution and confirming an accurate distribution range for each size of glycan within enoxaparin. In addition, randomly matched MS data can be corrected, with the constraint of the corresponding chromatographic retention time range, to remove most false positive data. The analytical stability of "Glycomapping" software was confirmed. Enoxaparin, prepared by different manufacturers and from different animal sources, was analyzed using "Glycomapping." Compared to raw data, data processed with "Glycomapping" are more robust and accurate. Another two LMWHs, nadroparin and dalteparin could also be analyzed with this software. This work lays a solid foundation for the automated analysis of heterogeneous mixtures of natural glycans, such as LMWHs and other complex oligosaccharides and polysaccharides.

Angle-selective chiral absorption induced by diffractive coupling in metasurfaces.

Here we report that a simple chiral metasurface with twisted metallic cut-wire arrays enables highly efficient and continuously tunable chiral absorption over a broad spectral range by scanning the incidence angle over a few degrees. The angle-selective chiral absorption results from the surface plasmon resonance (SPR) excited by diffractive effects of the metasurface. The diffraction-assisted chiral metasurface provides a straightforward strategy for achieving dynamically tunable chiral devices and offers intriguing possibilities for various applications in on-chip chiral detectors/emitters, chiral spectrometers, chiral lasers, and so on.

Forensic and phylogenetic analyses of populations in the Tibetan-Yi corridor using 41 Y-STRs.

Y-chromosome haplotypes of 527 non-related males (176 Han, 186 Tibetan, and 165 Yi) in the Tibetan-Yi corridor were analyzed using SureID® PathFinder Plus. In the populations of Han, Tibetans, and Yi, the haplotype diversity was 0.9989, 0.9981, and 0.9993, respectively, and the discrimination capacity was 0.9148, 0.8925, and 0.9576, respectively. Phylogenetic relationships among 12 studied ethnic groups and 7 other ethnic groups in the Tibetan-Yi corridor were investigated. Both multi-dimensional scaling analysis and phylogenetic reconstructions indicated that Tibetans appeared separated from the Han and Yi ethnic groups in the Tibetan-Yi corridor. Their genetic homogeneity or heterogeneity has not entirely been affected by their geographical distance and linguistic origin.

A typical antipsychotic treatment induced gradually expanding white matter alterations in healthy individuals with persistent auditory verbal hallucinations-an artificially controlled pilot study.

OBJECTIVE: The aim of this study was to explore the effects of atypical antipsychotics (AaPs) on brain white matter (WM) tracts in healthy individuals with auditory verbal hallucinations (Hi-AVHs). METHODS: We analyzed neuroimaging, AVH symptoms, and cognitive assessment data obtained from 39 Hi-AVHs who reported being distressed by persistent AVHs and volunteered to receive AaP treatment. We used tract-based spatial statistics (TBSS) and t tests to explore AaP pharmacotherapy effects on AVH symptoms and brain WM alterations in Hi-AVH subjects. RESULTS: TBSS and t tests revealed WM alterations after AaP treatment, relative to pretreatment observations. Although AaPs alleviated AVH symptoms, WM alterations in these subjects expanded over 8 months of AaP treatment, encompassing most major WM tracts by the end of the observation period, including the corpus callosum, arcuate fasciculus, cortico-spinal tracts, anterior commissure, and posterior commissure. CONCLUSIONS: The worsening of AaP-associated WM alterations observed in this study suggest that AaPs may not be a good choice for the treatment of Hi-AVHs despite their ability to alleviate AVHs.

Factors related to mental health of inpatients with COVID-19 in Wuhan, China.

OBJECTIVE: To evaluate the mental health status of hospitalized patients with coronavirus disease 2019 (COVID-19) and to explore the related factors. METHOD: This was a cross-sectional survey among COVID-19 inpatients in two isolation wards of a designated hospital in Wuhan, China, from March 7, 2020, to March 24, 2020. Participants' demographic data, clinical data and levels of circulating inflammatory markers were collated. Mental health symptoms were evaluated with questionnaires, which included the Insomnia Severity Index (ISI) scale, the 9-item Patient Health Questionnaire (PHQ-9), the 7-item Generalized Anxiety Disorder (GAD-7) scale, and questions about patients' self-perceived illness severity. Multivariate linear regression analysis was performed to explore factors that associated with mental symptoms, and a structural equation model (SEM) was used to assess the possible relationships between those factors and the patients' mental health. RESULTS: Among the 85 participants, 45.9% had symptoms of depression (PHQ-9 ≥ 5), 38.8% had anxiety (GAD-7 ≥ 5), and 54.1% had insomnia (ISI ≥ 8). According to multivariate regression analysis, female sex, a higher level of interleukin (IL)-1ß and greater self-perceived illness severity were all significantly associated with a higher PHQ-9 score, higher GAD-7 score and higher ISI score. In addition, the disease duration and the neutrophil to lymphocyte ratio (NLR) were positively related to patients' self-perceived illness severity. The results of the SEM analyses suggested that sex (ß = 0.313, P < 0.001), self-perceived illness severity (ß = 0.411, P < 0.001) and levels of inflammatory markers (ß = 0.358, P = 0.002) had direct effects on patients' mental health. The disease duration (ß = 0.163, P = 0.003) and levels of inflammatory markers (ß = 0.101, P = 0.016) also indirectly affected patients' mental health, with self-perceived illness severity acting as a mediator. CONCLUSION: A majority of COVID-19 infected inpatients reported experiencing mental health disturbances. Female sex, disease duration, levels of inflammatory markers and self-perceived illness severity are factors that could be used to predict the severity of patients' mental symptoms.

Using engineered 6-O-sulfotransferase to improve the synthesis of anticoagulant heparin.

Heparan sulfate (HS) and heparin are sulfated polysaccharides exhibiting diverse physiological functions. HS 6-O-sulfotransferase (6-OST) is a HS biosynthetic enzyme that transfers a sulfo group to the 6-OH position of glucosamine to synthesize HS with desired biological activities. Chemoenzymatic synthesis is a widely adopted method to obtain HS oligosaccharides to support biological studies. However, this method is unable to synthesize all possible structures due to the specificity of natural enzymes. Here, we report the use of an engineered 6-OST to achieve fine control of the 6-O-sulfation. Unlike wild type enzyme, the engineered 6-OST only sulfates the non-reducing end glucosamine residue. Utilizing the engineered enzyme and wild type enzyme, we successfully completed the synthesis of five hexasaccharides and one octasaccharide differing in 6-O-sulfation patterns. We also identified a hexasaccharide construct as a new anticoagulant drug candidate. Our results demonstrate the feasibility of using an engineered HS biosynthetic enzyme to prepare HS-based therapeutics.

Negative-Ion Mode Capillary Isoelectric Focusing Mass Spectrometry for Charge-Based Separation of Acidic Oligosaccharides.

Glycosaminoglycans (GAGs) are biologically and pharmacologically important linear, anionic polysaccharides containing various repeating disaccharides sequences. The analysis of these polysaccharides generally relies on their chemical or enzymatic breakdown to disaccharide units that are separated, by chromatography or electrophoresis, and detected, by UV, fluorescence, or mass spectrometry (MS). Isoelectric focusing (IEF) is an important analytical technique with high resolving power for the separation of analytes exhibiting differences in isoelectric points. One format of IEF, the capillary isoelectric focusing (cIEF), is an attractive approach in that it can be coupled with mass spectrometry (cIEF-MS) to provide online focusing and detection of complex mixtures. In the past three decades, numerous studies have applied cIEF-MS methods to the analysis of protein and peptide mixtures by positive-ion mode mass spectrometry. However, polysaccharide chemists largely rely on negative-ion mode mass spectrometry for the analysis of highly sulfated GAGs. The current study reports a negative-ion mode cIEF-MS method using an electrokinetically pumped sheath liquid nanospray capillary electrophoresis-mass spectrometry (CE-MS) coupling technology. The feasibility of this negative-ion cIEF-MS method and its potential applications are demonstrated using chondroitin sulfate and heparan sulfate oligosaccharides mixtures.

Systematic analysis of enoxaparins from different sources with online one- and two-dimensional chromatography.

Enoxaparin, one of the most important low-molecular-weight heparins (LMWHs), is widely used as a clinical anticoagulant. Different production processes and animal sources of its precursor (unfractionated heparin) can result in the structural diversity of enoxaparin. In this study, 38 lots of enoxaparin prepared at different times, from different providers and animal sources, were systematically analyzed. SEC and SAX were used to analyze the oligosaccharide dispersity and structural compositions (disaccharide domains) of enoxaparins by size and charge, respectively. The results provide clues as to whether the structural variations in enoxaparin, observed in oligosaccharide mapping and/or disaccharide analysis, are attributable to differences in the animal sources of its heparin precursor or enoxaparin production processes based on times or brands. The representative enoxaparins were fingerprinted with online multiple heart-cut two-dimensional liquid chromatography-mass spectrometry (MHC-2DLC-MS). The profiles in MHC-2DLC-MS showed the detailed structural information of enoxaparins. In addition, the binding capacities to antithrombin III (AT) of these 38 lots of enoxaparins were detected using surface plasmon resonance (SPR) with the competitive inhibition mode. The results showed that the glycan size distribution of an enoxaparin is more related to its production process. The disaccharide composition, sequence and the variety of glycans of an enoxaparin are more related to its AT binding-based anticoagulant activity.

[Molecular Mechanism and family research of a pedigree with B(A).06 subtype].

OBJECTIVE: To explore the serological and genotypic characteristics of a pedigree with B(A).06 subtype. METHODS: Serological methods was used to identify the ABO phenotypes. Exons 6 and 7 of the ABO gene and flanking regions were subjected to direct sequencing and TA clonal sequencing in order to determine the genotype of individuals with inconsistent results for forward and reverse serological typing. RESULTS: Among 12 individuals from 4 generations, 5 were identified with a AwB phenotype, along with a c.803C>G mutation in exon 7 of the B allele, which was named as B(A).06. The B(A).06/O.01.01 phenotype may be easily missed due to its weak anti-A antibody in the serum upon initial serological test. CONCLUSION: A B(A).06 subtype family was identified. The serological phenotype of individuals carrying the B(A).06 allele may be affected by the opposite DNA strand.

Heterologous expression, characterization and possible functions of the chitin deacetylases, Cda1 and Cda2, from mushroom Coprinopsis cinerea.

Two chitin deacetylases, Cda1 and Cda2, from Coprinopsis cinerea were expressed and characterized. Cda1 preferably deacetylates the nonreducing end residue of (GlcNAc)2, the internal or nonreducing end residue of (GlcNAc)3 and the nonreducing residue of (GlcNAc)6 after deacetylating the internal residues. In contrast, Cda2 preferably deacetylates the reducing end residue of (GlcNAc)2, the internal or reducing end residue of (GlcNAc)3 and the reducing residue of (GlcNAc)6 after deacetylating the internal residues. Furthermore, Cda1 prefers chitohexaose with higher degrees of acetylation for deacetylation, while Cda2 shows a weaker preference for chitohexaose with varying degrees of acetylation. The predicted Cda1 structure shows more hydrophobic aromatic amino acids on the surface near subsite +1 in the active site than on the surface near subsite -1, whereas the predicted Cda2 structure has more hydrophobic aromatic amino acids on the surface near subsite -1 than on the surface near subsite +1, which may be the molecular basis of the distinctive catalytic features between Cda1 and Cda2. Notably, Cda1 has a high transcription level in the nonelongating basal stipe region, whereas Cda2 has a high transcription level in the elongating apical stipe region, and the transcription level of the former is approximately five times that of the latter. Correspondingly, the molar ratio of GlcN/GlcNAc increased from 0.15 in the cell wall of the apical stipe region to 0.22 in the cell wall of the basal stipe region. Different modes of action of Cda1 and Cda2 may be related to their functions in the different stipe regions.

Quadrupole Orbitrap Mass Spectrometer-Based Metabonomic Elucidation of Influences of Short-Term Di(2-ethylhexyl) phthalate Exposure on Cardiac Metabolism in Male Mice.

Di(2-ethylhexyl) phthalate (DEHP) can cause severe environmental pollution. Effects of DEHP on cardiac metabolism have been reported, but its mechanism(s) of action is not fully clear. Here, we used high-resolution mass spectrometry for metabonomics and molecular biological methods to identify the different endogenous metabolites affected by DEHP that might cause changes in cardiac metabolism in mice, map the network of metabolic pathways, and reveal (at the molecular level) how DEHP affects cardiac metabolism. The results showed that DEHP could inhibit the ß-oxidation of fatty acids and gluconeogenesis, promote glycolysis, and inhibit the tricarboxylic acid cycle in cardiomyocytes. DEHP caused mitochondrial dysfunction by inhibiting the synthesis and transport of fatty acids and, thus, inhibiting the synthesis and breakdown of adenosine triphosphate in mitochondria. Pathology revealed that DEHP could change the normal structures and functions of the heart and bodies of mice. DEHP can interfere with the physiological and metabolic function of the heart in mice by disrupting the endogenous metabolite and gene levels.

Glycosylation status of bone sialoprotein and its role in mineralization.

The highly glycosylated bone sialoprotein (BSP) is an abundant non-collagenous phosphoprotein in bone which enhances osteoblast differentiation and new bone deposition in vitro and in vivo. However, the structural details of its different glycosylation linkages have not been well studied and their functions in bone homeostasis are not clear. Previous studies suggested that the O-glycans, but not the N-glycans on BSP, are highly sialylated. Herein, we employed tandem mass spectrometry (MS/MS) to demonstrate that the N-glycanson the recombinant human integrin binding sialoprotein (rhiBSP) are also enriched in sialic acids (SAs) at their termini. We also identified multiple novel sites of N-glycan modification. Treatment of rhiBSP enhances osteoblast differentiation and mineralization of MC3T3-E1 cells and this effect could be partially reversed by efficient enzymatic removal of its N-glycans. Removal of all terminal SAs has a greater effect in reversing the effect of rhiBSP on osteogenesis, especially on mineralization, suggesting that sialylation at the termini of both N-glycans and O-glycans plays an important role in this regulation. Moreover, BSP-conjugated SAs may affect mineralization via ERK activation of VDR expression. Collectively, our results identified novel N-glycans enriched in SAs on the rhiBSP and demonstrated that SAs at both N- and O-glycans are important for BSP regulation of osteoblast differentiation and mineralization in vitro.

Accumulation of intact sulfur mustard in adipose tissue and toxicokinetics by chemical conversion and isotope-dilution liquid chromatography-tandem mass spectrometry.

Sulfur mustard (SM) is a powerful vesicant and one of the most harmful chemical warfare agents. Although having been studied for a long time, it is still difficult to fully elucidate the mechanisms of SM poisoning, and there is no effective antidote or specific treatment for SM injury. The investigations on toxicokinetics and tissue distribution of SM will help to understand its toxicity and provide a theoretical basis for pretreatment and therapy of SM poisoning. But the metabolic trajectory or fate of intact SM in vivo remains unclear, and there are insufficient experimental data to elucidate, due to its high reactivity and difficulty in biomedical sample analysis. In this paper, a sensitive method for the detection and quantification of intact SM in blood or tissues using isotope-dilution LC-MS/MS coupled with chemical conversion was developed. By transforming highly reactive SM into stable derivative product, the real concentration of intact SM in biological samples was obtained accurately. The toxicokinetics and tissue distribution studies of intact SM in rats were successfully profiled by the novel method after intravenous (10 mg/kg) or cutaneous administration (1, 3 and 10 mg/kg). The SM level in blood with peak time at 30-60 min determined in cutaneous exposure experiment was found much higher than previously reported, and the mean residence time in blood extended to 1-1.5 h. A significant accumulation of intact SM was observed in adipose tissues, including the perirenal fat, epididymal fat, subcutaneous fat and brown fat, in which the concentrations of SM were at least 15 times greater than those in non-adipose tissues in cutaneous exposed rats. The recovery of SM in body fat was calculated as 3.3 % of bioavailable SM (the bioavailability after cutaneous exposure was evaluated as 16 %). Thus, the adipose tissue was important for SM distribution and toxicity, which may pioneer a new model for both the prevention and treatment of SM exposure.

A rapid and efficient analytical method for the quantification of a novel anticholinergic compound, R-phencynonate, by stable isotope-dilution LC-MS/MS and its application to bioavailability and dose proportionality studies.

A rapid, specific and high-throughput stable isotope-dilution LC-MS/MS method was developed and validated with high sensitivity for the quantification of R-phencynonate (a eutomer of phencynonate racemate) in rat and dog plasma. Plasma samples were deproteinized using acetonitrile and then separated on a C8 column with an isocratic mobile phase containing acetonitrile-water-formic acid mixture (60:40:0.1, v/v/v) at a flow rate of 0.2 mL/min. Each sample had a total run time of 3 min. Quantification was performed using triple quadrupole mass spectrometry in selected reaction monitoring mode with positive electrospray ionization. The method was shown to be highly linear (r2 > 0.99) and to have a wide dynamic range (0.1-100 ng/mL) with favourable accuracy and precision. No matrix effects were observed. The detailed pharmacokinetic profiles of R-phencynonate at therapeutic doses in rats and dogs were characterized by rapid oral absorption, quick clearance, high volume of distribution and poor absolute bioavailability. R-Phencynonate lacked dose proportionality over the oral dose range, based on the power model. However, the area under concentration-time curve and the maximum plasma concentration increased linearly in a dose-dependent manner in both animal models. The absolute bioavailability of R-phencynonate was 16.6 ± 2.75 and 4.78 ± 1.26% in dogs and rats, respectively.

Reaction of Oxidized Polysialic Acid and a Diaminooxy Linker: Characterization and Process Optimization Using Nuclear Magnetic Resonance Spectroscopy.

Native polysialic acid (natPSA) is a high-molecular-weight glycan composed of repeat units of α-(2 → 8) linked N-acetylneuraminic acid (Neu5Ac). Mild periodate oxidation of PSA selectively targets the end sialic acid ring containing three adjacent alcohols generating a putative aldehyde, which can be used, after attachment of a linker molecule, for terminal attachment of PSA to protein. Previously, we showed that the oxidized PSA (oxoPSA) contained a hemiacetal at the oxidation site and can react with a linker containing an aminooxy group in a conjugation reaction to form a stable oxime linkage. Thus, reagents containing an aminooxy group may be prepared for conjugation of PSA to the carbohydrate moiety of therapeutic proteins, thereby increasing their half-life. These aminooxy-PSA reagents can selectively react with aldehyde groups generated by mild NaIO4 oxidation of glycans on the surface of the target protein. To comprehend the conjugation, unoxidized tetrasialic acid and Neu5Ac were reacted in model reactions with a diaminooxy linker to define the nuclear magnetic resonance (NMR) chemical shifts. Based on these data, we were able to show that, in the case of PSA, the reaction with the linker occurs not only at the expected oxidized end to form an aldoxime but also at the end distal to the oxidation to form a ketoxime. We determined that, in aged solutions, both oxoPSA and PSA aldoxime were hydrolyzed. PSA aldoxime was also shown to disproportionate to form a dimer (PSA-linker-PSA), which then could react further with the released linker at one of its PSA termini. Furthermore, NMR was used to monitor the effects of deliberate process changes so that conditions could be optimized for attachment of linker at the desired end of the PSA chain, which led to a well-defined product.

Controllable lasing behavior enabled by compound dielectric waveguide grating structures.

The photonic density of states (PDOS) is one of the key physical quantities governing the lasing behavior for photonic band-edge lasers. The PDOS is conventionally altered by exploiting the high-Q band-edge mode within a device, which is typically achieved by increasing the contrast of periodic refractive index variation (Δn) or increasing the periodic number of the photonic crystals. In this paper, we propose a different approach to achieve a high-Q band edge mode within an active compound dielectric waveguide grating (CWDG). We demonstrate that the lasing threshold and intensity can be flexibly tuned by changing the filling factors of the CWDG. This design can effectively improve the performance of electrically pumped photonic band-edge lasers.

Development of hydrophilic interaction chromatography with quadruple time-of-flight mass spectrometry for heparin and low molecular weight heparin disaccharide analysis.

RATIONALE: Heparin and low molecular weight heparin (LMWH) are widely used as clinical anticoagulants. The determination of their composition and structural heterogeneity still challenges analysts. METHODS: Disaccharide compositional analysis, utilizing heparinase-catalyzed depolymerization, is one of the most important ways to evaluate the sequence, structural composition and quality of heparin and LMWH. Hydrophilic interaction chromatography coupled with quadruple time-of-flight mass spectrometry (HILIC/QTOFMS) has been developed to analyze the resulting digestion products. RESULTS: HILIC shows good resolution and excellent MS compatibility. Digestion products of heparin and LMWHs afforded up to 16 compounds that were separated using HILIC and analyzed semi-quantitatively. These included eight common disaccharides, two disaccharides derived from chain termini, three 3-O-sulfo-group-containing tetrasaccharides, along with three linkage region tetrasaccharides and their derivatives. Structures of these digestion products were confirmed by mass spectral analysis. The disaccharide compositions of a heparin, two batches of the LMWH, enoxaparin, and two batches of the LMWH, nadroparin, were compared. In addition to identifying disaccharides, 3-O-sulfo-group-containing tetrasaccharides, linkage region tetrasaccharides were observed having slightly different compositions and contents in these heparin products suggesting that they had been prepared using different starting materials or production processes. CONCLUSIONS: Thus, compositional analysis using HILIC/QTOFMS offers a unique insight into different heparin products.