Structural basis for directional chitin biosynthesis.

Chitin, the most abundant aminopolysaccharide in nature, is an extracellular polymer consisting of N-acetylglucosamine (GlcNAc) units1. The key reactions of chitin biosynthesis are catalysed by chitin synthase2-4, a membrane-integrated glycosyltransferase that transfers GlcNAc from UDP-GlcNAc to a growing chitin chain. However, the precise mechanism of this process has yet to be elucidated. Here we report five cryo-electron microscopy structures of a chitin synthase from the devastating soybean root rot pathogenic oomycete Phytophthora sojae (PsChs1). They represent the apo, GlcNAc-bound, nascent chitin oligomer-bound, UDP-bound (post-synthesis) and chitin synthase inhibitor nikkomycin Z-bound states of the enzyme, providing detailed views into the multiple steps of chitin biosynthesis and its competitive inhibition. The structures reveal the chitin synthesis reaction chamber that has the substrate-binding site, the catalytic centre and the entrance to the polymer-translocating channel that allows the product polymer to be discharged. This arrangement reflects consecutive key events in chitin biosynthesis from UDP-GlcNAc binding and polymer elongation to the release of the product. We identified a swinging loop within the chitin-translocating channel, which acts as a 'gate lock' that prevents the substrate from leaving while directing the product polymer into the translocating channel for discharge to the extracellular side of the cell membrane. This work reveals the directional multistep mechanism of chitin biosynthesis and provides a structural basis for inhibition of chitin synthesis.

Photosynthetic Phosphoribulokinase Structures: Enzymatic Mechanisms and the Redox Regulation of the Calvin-Benson-Bassham Cycle.

The Calvin-Benson-Bassham (CBB) cycle is responsible for CO2 assimilation and carbohydrate production in oxyphototrophs. Phosphoribulokinase (PRK) is an essential enzyme of the CBB cycle in photosynthesis, catalyzing ATP-dependent conversion of ribulose-5-phosphate (Ru5P) to ribulose-1,5-bisphosphate. The oxyphototrophic PRK is redox-regulated and can be further regulated by reversible association with both glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and oxidized chloroplast protein CP12. The resulting GAPDH/CP12/PRK complex is central in the regulation of the CBB cycle; however, the PRK-CP12 interface in the recently reported cyanobacterial GAPDH/CP12/PRK structure was not well resolved, and the detailed binding mode of PRK with ATP and Ru5P remains undetermined, as only apo-form structures of PRK are currently available. Here, we report the crystal structures of cyanobacterial (Synechococcus elongatus) PRK in complex with ADP and glucose-6-phosphate and of the Arabidopsis (Arabidopsis thaliana) GAPDH/CP12/PRK complex, providing detailed information regarding the active site of PRK and the key elements essential for PRK-CP12 interaction. Our structural and biochemical results together reveal that the ATP binding site is disrupted in the oxidized PRK, whereas the Ru5P binding site is occupied by oxidized CP12 in the GAPDH/CP12/PRK complex. This structure-function study greatly advances the understanding of the reaction mechanism of PRK and the subtle regulations of redox signaling for the CBB cycle.

Role of miR-211 in a PC12 cell model of Alzheimer's disease via regulation of neurogenin 2.

NEW FINDINGS: What is the central question of this study? What is the mechanism of miR-211 in an Alzheimer's disease cell model? What is the main finding and its importance? miR-211 was upregulated in an Alzheimer's disease cell model. It targeted neurogenin 2, reduced the activation of the phosphoinositide 3-kinase-Akt signalling pathway, inhibited the proliferation of the Alzheimer's disease cell model and promoted apoptosis. ABSTRACT: MicroRNAs (miRs) are aberrantly expressed in Alzheimer's disease (AD) patients. This study was intended to investigate the effect of miR-211 on an AD cell model and the involvement of neurogenin 2 (Ngn2). The appropriate dose and time for the effect of Aß1-42 on PC12 cells were determined to establish an AD cell model. An effect of miR-211 expression on cell viability, proliferation and apoptosis was detected after cell transfection. Online prediction and a dual luciferase reporter gene assay were utilized to confirm the binding sequence of miR-211 and Ngn2. qRT-PCR and western blot analysis were applied to measure Ngn2 expression. A gain and loss of function assay of miR-211 and Ngn2 was performed, and activation of the phosphoinositide 3-kinase (PI3K)-Akt signaling pathway was detected. The AD cell model was induced by Aß1-42 treatment. miR-211 expression was significantly enhanced after miR-211 transfection, leading to suppressed proliferation and promotion of apoptosis in Aß1-42 -treated PC12 cells. In addition, miR-211 could downregulate Ngn2 mRNA and protein expression, while overexpression of Ngn2 could reverse the effects of miR-211 on Aß1-42 -treated PC12 cells and significantly enhance the phosphorylated Akt and PI3K protein levels. miR-211 could inhibit growth of PC12 cells by suppressing Ngn2 expression and inactivating the PI3K-Akt signalling pathway.

A Correlational Study on Cerebral Microbleeds and Carotid Atherosclerosis in Patients with Ischemic Stroke.

PURPOSE: This study aimed to investigate the correlation between cerebral microbleeds and carotid atherosclerosis in patients with ischemic stroke. SUBJECTS AND METHODS: Patients with ischemic stroke treated in a hospital in China from 2016 to 2017 were enrolled in the study. Based on the results from susceptibility-weighted imaging, the patients were divided into cerebral microbleed and noncerebral microbleed groups. The degree of carotid atherosclerosis was assessed with carotid intima-media thickness (CIMB) and Crouse score of carotid plaque. The details of patients' demographic information, cerebrovascular disease-related risk factors, carotid atherosclerosis indices, cerebral microbleed distribution, and grading were recorded, compared, and analyzed. RESULTS: Logistic regression analysis of the 198 patients showed that CIMB and Crouse score were significantly correlated with the occurrence of cerebral microbleeds. The CIMB thickening group (P = .03) and the plaque group (P = .01) were more susceptible to cerebral microbleeds. In the distribution of cerebral microbleed sites, Crouse scores were the highest in the mixed group and showed a statistically significant difference (P < .01). As the degree of carotid atherosclerosis increased, the average number of cerebral microbleeds also increased (P < .01). The receiver operating characteristic curve analysis of the carotid atherosclerosis indices showed a statistically significant difference. The CIMB value combined with the Crouse score was the best indicator (P < .01). CONCLUSION: In patients with ischemic stroke, cerebral microbleeds are closely related to carotid atherosclerosis. Active control of carotid atherosclerosis is important to prevent cerebral microbleeds in patients with ischemic stroke.

Diagnostic accuracy of the soluble Fms-like tyrosine kinase-1/placental growth factor ratio for preeclampsia: a meta-analysis based on 20 studies.

PURPOSE: To investigate the accuracy of the soluble fms-like tyrosine kinase-1(sFlt-1)/placental growth factor (PlGF) ratio to predict preeclampsia (PE). METHODS: A search in the PubMed, Embase, and Cochrane Library was conducted for human studies without language restriction. We included the studies reported sufficient data to reconstruct the diagnostic 2 × 2 table of sFlt-1/PlGF with testing of PlGF and sFlt-1 in serum or plasma. Two reviewers independently screened the articles. Disagreements were resolved by a third reviewer. Unpublished data were requested from the authors of the study by email. RESULTS: Twenty studies with 28 groups of women with different gestational ages were included in our study. The pooled diagnostic sensitivity and specificity of sFlt-1/PlGF were 0.78 and 0.84 with the area under the SROC curve (AUC) of 0.88. In subgroup analyses, the diagnostic value of sFlt-1/PlGF for early-onset PE is highest with a pooled diagnostic odds ratio (DOR) of 241 and AUC of 0.98. CONCLUSIONS: The accuracy of sFlt-1/PlGF ratio for screening PE was moderate and was high for early-onset PE. High-quality studies are needed to confirm their usefulness in prediction of PE in clinical practice.

Advances in understanding insect chitin biosynthesis.

Chitin, a natural polymer of N-acetylglucosamine chains, is a principal component of the apical extracellular matrix in arthropods. Chitin microfibrils serve as structural components of natural biocomposites present in the extracellular matrix of a variety of invertebrates including sponges, molluscs, nematodes, fungi and arthropods. In this review, we summarize the frontier advances of insect chitin synthesis. More specifically, we focus on the chitin synthase (CHS), which catalyzes the key biosynthesis step. CHS is also known as an attractive insecticidal target in that this enzyme is absent in mammals, birds or plants. As no insect chitin synthase structure have been reported so far, we review recent studies on glycosyltransferase domain structures derived from fungi and oomycetes, which are conserved in CHS from all species containing chitin. Auxiliary proteins, which coordinate with CHS in chitin biosynthesis and assembly, are also discussed.

Absorbed Bioactive Compounds Replicate Guanxin II-Induced Endothelium-Associated in/ex vivo Vasodilation.

OBJECTIVE: To develop an interference-free and rapid method to elucidate Guanxin II (GX II)'s representative vasodilator absorbed bioactive compounds (ABCs) among enormous phytochemicals. METHODS: The contents of ferulic acid, tanshinol, and hydroxysafflor yellow A (FTA) in GX II/rat serum after the oral administration of GX II (30 g/kg) were detected using ultra-performance liquid chromatography-mass spectrometry. Totally 18 rats were randomly assigned to the control group (0.9% normal saline), GX II (30 g/kg) and FTA (5, 28 and 77 mg/kg) by random number table method. Diastolic coronary flow velocity-time integral (VTI), i.e., coronary flow or coronary flow-mediated dilation (CFMD), and endothelium-intact vascular tension of isolated aortic rings were measured. After 12 h of exposure to blank medium or 0.5 mmol/L H2O2, endothelial cells (ECs) were treated with post-dose GX II of supernatant from deproteinized serum (PGSDS, 300 µL PGSDS per 1 mL of culture medium) or FTA (237, 1539, and 1510 mg/mL) for 10 min as control, H2O2, PGSDS and FTA groups. Nitric oxide (NO), vascular endothelial growth factor (VEGF), endothelin-1 (ET-1), superoxide dismutase (SOD), malondialdehyde (MDA) and phosphorylated phosphoinositide 3 kinase (p-PI3K), phosphorylated protein kinase B (p-AKT), phosphorylated endothelial nitric oxide synthase (p-eNOS) were analyzed. PGSDS was developed as a GX II proxy of ex vivo herbal crude extracts. RESULTS: PGSDS effectively eliminates false responses caused by crude GX II preparations. When doses equaled the contents in GX II/its post-dose serum, FTA accounted for 98.17% of GX II -added CFMD and 92.99% of PGSDS-reduced vascular tension. In ECs, FTA/PGSDS was found to have significant antioxidant (lower MDA and higher SOD, P<0.01) and endothelial function-protective (lower VEGF, ET-1, P<0.01) effects. The increases in aortic relaxation, endothelial NO levels and phosphorylated PI3K/Akt/eNOS protein induced by FTA/PGSDS were markedly abolished by NG-nitro-L-arginine methyl ester (L-NA, eNOS inhibitor) and wortmannin (PI3K/AKT inhibitor), respectively, indicating an endothelium-dependent vasodilation via the PI3K/AKT-eNOS pathway (P<0.01). CONCLUSION: This study provides a strategy for rapidly and precisely elucidating GX II's representative in/ex vivo cardioprotective absorbed bioactive compounds (ABCs)-FTA, suggesting its potential in advancing precision ethnomedicine.

Job burnout among primary healthcare workers during COVID-19 pandemic: cross-sectional study in China.

Objective: This study evaluated job burnout among primary healthcare workers (PHCWs) in China during the COVID-19 pandemic, explored its influencing factors, and examined PHCWs' preferences for reducing job burnout. Method: We conducted a multicenter cross-sectional study in Heilongjiang, Sichuan, Anhui, Gansu, and Shandong Provinces. An electronic questionnaire survey was conducted through convenience sampling in communities from May to July 2022. We collected sociodemographic characteristics, job burnout level, job satisfaction, and preferred ways to reduce job burnout among PHCWs. Results: The job burnout rate among PHCWs in China was 59.87% (937/1565). Scores for each dimension of job burnout were lower among PHCWs who had a better work environment (emotional exhaustion OR: 0.60; depersonalization OR: 0.73; personal accomplishment OR: 0.76) and higher professional pride (emotional exhaustion OR: 0.63; depersonalization OR: 0.70; personal accomplishment OR: 0.44). PHCWs with higher work intensity (emotional exhaustion OR: 2.37; depersonalization OR: 1.34; personal accomplishment OR: 1.19) had higher scores in all job burnout dimensions. Improving work environments and raising salaries were the preferred ways for PHCWs to reduce job burnout. Conclusion: Strategies should be developed to improve job satisfaction among PHCWs, enhance their professional identity, and alleviate burnout to ensure the effective operation of the healthcare system, especially during periods of overwork.

Effects of Group Music Intervention on Depression for Elderly People in Nursing Homes.

Depression is the most common mental problem among the elderly, especially in long-term care facilities. The purpose of the present study was to examine the effects of group music intervention on depression for elderly people in nursing homes. Methods: A randomized control trial consisting of sixty-three elderly participants randomly and blindly assigned to a music group or control group was utilized. The music group received 20 sessions of group music intervention (two 30-min sessions per week for 10 weeks), and the control group received usual care with no music intervention. The Geriatric Depression Scale-Short Form (GDS-SF) and salivary cortisol at baseline, 5 weeks, and 10 weeks were collected for analysis. Results of the GEEs (generalized estimating equations) analysis indicated that after 20 sessions for 10 weeks of group music intervention, the groups showed a statistically significant difference in depression at 5 weeks and 10 weeks. There was no significant difference in the salivary cortisol concentration between the two groups. The results show that the group music intervention may effectively reduce the depression scores for elderly people in nursing homes. Conclusion: The group music intervention has positive effects on depression.

Drug-peptide supramolecular hydrogel boosting transcorneal permeability and pharmacological activity via ligand-receptor interaction.

Boosting transcorneal permeability and pharmacological activity of drug poses a great challenge in the field of ocular drug delivery. In the present study, we propose a drug-peptide supramolecular hydrogel based on anti-inflammatory drug, dexamethasone (Dex), and Arg-Gly-Asp (RGD) motif for boosting transcorneal permeability and pharmacological activity via the ligand-receptor interaction. The drug-peptide (Dex-SA-RGD/RGE) supramolecular hydrogel comprised of uniform nanotube architecture formed spontaneously in phosphate buffered saline (PBS, pH = 7.4) without external stimuli. Upon storage at 4 °C, 25 °C, and 37 °C for 70 days, Dex-SA-RGD in hydrogel did not undergo significant hydrolysis, suggesting great long-term stability. In comparison to Dex-SA-RGE, Dex-SA-RGD exhibited a more potent in vitro anti-inflammatory efficacy in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages via the inhibition of nuclear factor кB (NF-κB) signal pathway. More importantly, using drug-peptide supramolecular hydrogel labeled with 7-nitro-2,1,3-benzoxadiazole (NBD), the Dex-SA-K(NBD)RGD showed increased performance in terms of integrin targeting and cellular uptake compared to Dex-SA-K(NBD)RGE, as revealed by cellular uptake assay. On topical instillation in rabbit's eye, the proposed Dex-SA-K(NBD)RGD could effectively enhance the transcorneal distribution and permeability with respect to the Dex-SA-K(NBD)RGE. Overall, our findings demonstrate the performance of the ligand-receptor interaction for boosting transcorneal permeability and pharmacological activity of drug.

Ursolic acid inhibits Th17 cell differentiation via STAT3/RORγt pathway and suppresses Schwann cell-mediated Th17 cell migration by reducing CXCL9/10 expression.

Th17 cells represent important immune cells. Ursolic acid (UA) can regulate immune cell activities. This study was aimed to explore the effects of UA on Th17 cell differentiation and Schwann cell(SCs)-mediated migration and the potential mechanism. Naïve CD4+ T cells were isolated from rat peripheral blood, induced for Th17 cell differentiation, and treated with UA. The proportion of Th17 cells was detected by flow cytometry assay. SCs were co-cultured with Th17 cells. Th17 cell migration was detected by Transwell assay. The molecule expression was determined by Western blot and qRT-PCR. UA inhibited the Th17 cell differentiation and suppressed the STAT3/RORγt pathway. STAT3 overexpression up-regulated p-STAT3 and RORγt expression and promoted Th17 cell differentiation under the UA treatment. In LPS- and IFN-γ-stimulated-SCs, UA suppressed the expression of chemokines CXCL9/10, but had no significant effect of CCL20 expression. The expression CXCL9/10 receptor CXCR3 was higher in Th17 cells than that in Treg cells, while the expression CCL20 receptor CCR6 was lower in Th17 cells than that in Treg cells. UA, anti-CXCR3, and anti-CCR6 treatment inhibited SCs-mediated Th17 cell migration, and anti-CXCR3 exerted stronger inhibitory effect than Anti-CCR6. UA inhibited Th17 cell differentiation through STAT3/RORγt pathway and suppressed Th17 cell migration through down-regulating CXCL9/10 expression in SCs.

Glycol chitosan/oxidized hyaluronic acid hydrogel film for topical ocular delivery of dexamethasone and levofloxacin.

In the present study, we fabricated a glycol chitosan/oxidized hyaluronic acid hydrogel film with promising potential for the dual ophthalmic delivery of dexamethasone (Dex) and levofloxacin (Lev). Utilizing different oxidation degrees of oxidized hyaluronic acid (OHA), several blank hydrogel films and Lev-loaded hydrogel films were successfully fabricated. With an increase in the oxidation degree of OHA, the swelling ratio of the hydrogel films decreased accordingly. The hydrogel films displayed a stepwise release of Lev and Dex, with Lev rapidly released from the hydrogel film, followed by a sustained release of Dex. Lev-loaded hydrogel films revealed a potent capacity to inhibit bacterial growth in different bacterial strains. In lipopolysaccharide-activated RAW264.7 macrophages, the formulated hydrogel films displayed potent in vitro anti-inflammatory activity by significantly downregulating various inflammatory cytokines. Overall, the fabricated hydrogel film acting as a dual drug delivery system might be a promising vehicle for the treatment of postoperative endophthalmitis.

Mucoadhesive dexamethasone-glycol chitosan nanoparticles for ophthalmic drug delivery.

Self-assembly of drug-polysacrrides conjugates forming nanostructures provides a simple and promising strategy for the extension of precorneal retention and enhancement of corneal permeability. In the present study, a series of dexamethasone-glycol chitosan (Dex-GCS) conjugates were synthesized and thoroughly characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and ultraviolet-visible (UV-Vis) spectroscopy. The resulting Dex-GCS conjugates were able to self-assemble into nanoparticles spontaneously with particle sizes in the range of 277-289 nm and a positive charge of approximately +15 mV. Roughly spherical nanoparticles were observed by transmission electron microscopy (TEM). The in vitro mucoadhesive properties of Dex-GCS nanoparticles were evaluated by recording the variations in the zeta potential after incubation with different concentrations of mucin. In vitro release studies performed in phosphate-buffered saline (PBS, pH = 7.4) indicated progressive Dex release up to 8 h, followed by a plateau up to 48 h. Dex-GCS nanoparticles caused slight cytotoxicity against L929, HCEC and RAW 264.7 cells after 24 h of incubation and displayed a nearly identical anti-inflammatory efficacy to dexamethasone sodium phosphate (Dexp) in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. More importantly, the proposed Dex-GCS nanoparticles showed good ocular tolerance and provided a relatively longer precorneal duration compared with that of the aqueous solution formulation, which suggested that the self-assembled Dex-GCS nanoparticle might be a promising candidate for ophthalmic drug delivery.

Effects of Terminal Motif on the Self-Assembly of Dexamethasone Derivatives.

Tailoring the terminal motif of molecules including drugs might significantly affect their self-assembly tendency in aqueous solution, thus providing a rational strategy to modulate its macroscopic characteristics of supramolecular assembly. A model drug of dexamethasone (Dex) was esterified by different fatty acids [succinic acid (SA), glutaric acid (GA), and adipic acid (AA)] and aromatic acid [phthalic acid (PA)] to generate a series of Dex derivatives. Aqueous solution of Dex-SA, Dex-GA, and Dex-AA turned into hydrogel spontaneously after a period time of incubation (24, 48, and 72 h, respectively) via the auto-hydrolytic strategy, while aqueous solution of Dex-PA did not result in hydrogelation during 3 days of incubation. Aqueous solutions of Dex-SA, Dex-GA, and Dex-AA underwent apparent hydrolysis (10.73 ± 0.64%, 15.17 ± 2.24%, and 17.29 ± 1.39%, respectively), while Dex-PA exhibited a minimal hydrolysis (<1%) in a period of 28 days study, as indicated by in vitro hydrolytic test. Morphological observation showed that the hydrogel formed by Dex-SA was composed of uniform nanofibers, while hydrogels formed by Dex-GA, and Dex-AA were derived from irregular particles. The mechanical strength of hydrogel formed by Dex-SA was much bigger than that of hydrogels formed by Dex-GA and Dex-AA, as indicated by rheological test. Moreover, the acylation of Dex did not compromise its potent anti-inflammatory activity in a lipopolysaccharide (LPS)-activated RAW 264.7 macrophage.

A combination of inhibiting microglia activity and remodeling gut microenvironment suppresses the development and progression of experimental autoimmune uveitis.

Noninfectious (autoimmune and immune-mediated) uveitis is an ocular inflammatory disease which can lead to blindness in severe cases. Due to the potential side effects of first-line drugs for clinical uveitis, novel drugs and targets against uveitis are still urgently needed. In the present study, using rat experimental autoimmune uveitis (EAU) model, we first found that minocycline treatment can substantially inhibit the development of EAU and improve the retinal function by suppressing the retinal microglial activation, and block the infiltration of inflammatory cells, including Th17, into the retina by decreasing the major histocompatibility complex class II (MHC II) expression in resident and infiltrating cells. Moreover, we demonstrated that minocycline treatment can remodel the gut microenvironment of EAU rats by restoring the relative abundance of Ruminococcus bromii, Streptococcus hyointestinalis, and Desulfovibrio sp. ABHU2SB and promoting a functional shift in the gut via reversing the levels of L-proline, allicin, aceturic acid, xanthine, and leukotriene B4, and especially increasing the production of propionic acid, histamine, and pantothenic acid. At last, we revealed that minocycline treatment can significantly attenuate the progression of EAU after inflammation onset, which may be explained by the role of minocycline in the remodeling of the gut microenvironment since selective elimination of retinal microglia on the later stages of EAU was shown to have little effect. These data clearly demonstrated that inhibition of microglial activation and remodeling of the gut microenvironment can suppress the development and progression of experimental autoimmune uveitis. Considering the excellent safety profile of minocycline in multiple clinical experiments, we suggest that minocycline may have therapeutic implications for clinical uveitis.

Variations in leaf traits of Juniperus przewalskii from an extremely arid and cold environment.

How leaf traits vary with environmental and climatic variables in cold and arid environments is an essential issue in environmental ecology. Here, we analyzed the variations in leaf nitrogen (N) and phosphorus (P) stoichiometry and leaf dry matter content (LDMC) in Qilian juniper (Juniperus przewalskii Kom.) growing in 14 environmentally different plots on the northeastern Tibetan Plateau. The results showed that the N and P concentrations, N:P ratio and LDMC of Qilian juniper were 10.89 mg.g-1, 1.04 mg.g-1, 10.80 and 483.06 mg.g-1, respectively. The spatial coefficients of the variations in leaf N and P stoichiometry were significantly higher than the seasonal ones, and the correlations of leaf N and P concentrations with spatial variables were stronger than their correlations with the season. During the growing season, only the leaf N concentration and N:P ratio significantly increased. Soil nutrients were highly positively significantly correlated with leaf P concentrations but negatively correlated with the N:P ratio and LDMC. However, leaf N concentrations showed no significant correlations with soil nutrients. We suggest that the effects of temperature on the N concentration and LDMC were stronger than the effects of drought, while those on the P concentration and N:P ratio were weaker. Drought reduced leaf N and P concentrations and increased the N:P ratio and LDMC. In the arid region, with an increasing mean annual temperature (MAT), leaf N concentration significantly decreased, and LDMC significantly increased. In the semi-arid region, as MAT increased, leaf N and P concentrations significantly increased and LDMC and the N:P ratio significantly decreased. These opposite results supported the growth rate hypothesis that plant N and P concentrations increase while the N:P ratio and LDMC decrease as the growth rate increases.

Thermosensitive glycol chitosan-based hydrogel as a topical ocular drug delivery system for enhanced ocular bioavailability.

In the present study, we developed and evaluated an in situ gelling system based on hexanoyl glycol chitosan (H-GCS) for enhanced ocular bioavailability. An aqueous solution of H-GCS exhibited a typical sol-gel transition at 32 °C. The formed H-GCS hydrogel was characterized by rheology and scanning electron microscopy (SEM). H-GCS had minimal in vitro cytotoxicity against L-929 and HCEC cells over a concentration range of 0-0.8 mg/mL. Additionally, the H-GCS hydrogel exhibited good ocular tolerance and biocompatibility after a single instillation. Moreover, H-GCS hydrogel significantly prolonged the precorneal retention of fluorescein sodium compared with its aqueous solution. An in vivo pharmacokinetic study demonstrated that the levofloxacin-loaded H-GCS hydrogel could provide a significantly higher Cmax and AUC0-12h compared with the levofloxacin aqueous solution, thus increasing ocular bioavailability. Overall, the proposed H-GCS hydrogel acts as an in situ gelling system that might represent a promising vehicle for topical ocular drug delivery.

Chaihu-Shugan-San and absorbed meranzin hydrate induce anti-atherosclerosis and behavioral improvements in high-fat diet ApoE-/- mice via anti-inflammatory and BDNF-TrkB pathway.

The comorbidity of coronary heart disease (CHD) and depression in patients is extremely prevalent, with a rate from 20 to 50%, while depression-like behaviors exist in a larger percentage of patients. Therefore, the study of comorbidities is particularly urgent. Chaihu-Shugan-San (CSS), a classical traditional Chinese medicine formula, has been used to treat CHD with depression for hundreds of years. However, the mechanism of its action on comorbidities remains unclear. Here, we focused on the behavioral changes in ApoE-/- mice fed a high-fat diet (HFD) and elucidated the mechanism of CSS and its main absorbed component, meranzin hydrate (MH), as an anti-atherosclerosis and anti-depression agent. In the present study, mice were fed an HFD for 16 weeks and were intragastrically administered high and low doses of CSS and MH. Depressive-like behaviors were evaluated by the sucrose preference test, the open-field test, the light-dark test and the tail-suspension test, after which atherosclerotic plaques, plasma lipids, inflammatory cytokine levels and the expression of BDNF/TrkB were measured. We demonstrated that the atherosclerosis model group exhibited significant depressant behaviors. Moreover, CSS inhibited depressive-like behavioral changes, reduced atherosclerotic plaque areas, plasma total cholesterol, triglycerides, LDL-cholesterol levels and inflammatory cytokines including TNF-α, IL-1ß, and IL-6 in plasma and hippocampi, increased the protein and mRNA expression of BDNF and TrkB in the aorta and the hippocampus. Interestingly, MH, the main component in CSS that is absorbed in the plasma and hippocampus, exerted effects similar to those of CSS. In addition, MH increased the protein and mRNA expression of BDNF and TrkB in human umbilical vein endothelial cells (HUVECs) induced by LPS. Collectively, these results suggest that MH represents the CSS decoction, induces anti-atherosclerosis effects and improves depression-like behaviors in HFD-fed ApoE-/- mice. Moreover, the regulation of proinflammatory factors and BDNF-TrkB signaling are possibly involved in this process. Our findings indicate that MH is a potential phytochemical compound for the prevention of the comorbidity of atherosclerosis and depression.

Chromatographic studies of unusual on-column degradation of cefaclor observed in the impurity separation by HPLC.

An unpredictable ghost peak was intermittently observed during the impurity separation of cefaclor and formulation by high performance liquid chromatography (HPLC) with a content from below the reported threshold to approximately 0.3% in different laboratories. Through a series of investigations, the ghost peak was identified as an unusual on-column degradant of cefaclor formed under elevated column temperature but was not an actual sample impurity. The chemical structure of the degradant was determined by spectroscopic methods, including high resolution mass spectrometry (HRMS) and 1H-NMR. Consequently, the unknown peak was identified as a C-4 oxidative decarboxylation analog of cefaclor. The formation mechanism of the analog is proposed, and it is suggested that elevated column temperature during HPLC analysis has a profound effect on the degradation. Dissolved oxygen in the mobile phase may promote the formation of the ghost peak. The degradation can be suppressed by using a column temperature below 30 °C. Moreover, several other prevention measures are suggested based upon the results of the investigation.