Construction of heterocyclic rings from cyclopropenes

Heterocyclic rings are the fundamental building blocks of biological systems and have wide applications in synthetic chemistry and medicinal science. The development of novel synthetic methodology for heterocyclic skeletons from a variety of starting materials has made great progress in the past decades. Meanwhile, highly strained cyclopropenes as reactive reagents in organic transformations have drawn much attention from chemists. The rich chemical reactivity and reaction routes have been well investigated, and some review articles related to the reactivity of cyclopropenes and the construction of carbocycles and acyclic compounds have appeared in these years. Thus, this review mainly focuses on the progress in the construction of heterocyclic rings starting from various cyclopropenes including the reactions of commonly available stable cyclopropenes, in situ generated reactive cyclopropenes and cyclopropene precursors during this decade. Firstly, the transformations of common cyclopropenes into donor-type vinyl metal carbenes via transition metal induced ring opening, direct metalation of the CC bond of metal complexes, and cycloaddition reactions with 1,3-dipoles are described. Next, the annulation reactions of reactive cyclopropenes generated in situ with donor-acceptor reagents, intramolecular nucleophilic addition, and the cycloaddition reactions with 1,3-dipoles are introduced. Then, the transformation of cyclopropene precursors such as alkyl 1-chloro- or 1-alkoxy-2-aroylcyclopropanecarboxylates into five-membered heteroaromatic compounds is also mentioned. In addition, a brief outlook of the opportunity and challenges in the field of bio-orthogonal reactions related to cyclopropenes is given.

[Treatment of children's pharyngeal stenosis following pharyngeal surgery with coblation]

Objective:Pharyngeal stenosis as a postoperative complication following pharyngeal surgery (tonsillectomy/adenoidectomy) with coblation is rare and may be difficult to treat. This report is to explore the causes of pharyngeal stenosis and presents our successful treatment experience. Method:From Jan 2012 to July 2016, 5 children with pharyngeal stenosis (2 nasopharyngeal stenosis and 3 nasopharyngeal stenosis combined with oropharyngeal stenosis) secondary to pharyngeal surgery (tonsillectomy/adenoidectomy) in Peking Union Medical College Hospital were analyzed. Five cases with severe nasopharyngeal stenosis received surgery of scar resection, horizontal-to-vertical pharyngoplasty and local pharyngeal flap rotation; and three of them received free skin transplantation. After stenosis repair surgery, prolonged nasopharyngeal hollow stents were used for more than 6 months. To evaluate the therapeutic effect, pharyngeal cavities and symptoms of difficulty nasal breathing, mouth breathing, difficulty in blowing nose, hyponasal speech, snoring, restless sleep, anosmia, dysphagia were assessed and compared before and after surgery. Result:With 7-46 months follow-up, all symptoms of the 5 cases are ameliorated and the diameters of nasopharyx are more than 1.5 cm. No velopharyngeal insufficiency complication happened. Conclusion:Improper operation with coblation can cause severe pharyngeal stenosis. Flap rotation, horizontal-to-vertical pharyngoplasty and prolonged use nasopharyngeal hollow stents are reliable methods to correct pharyngeal stenosis following children's pharyngeal surgery.

[Clinical analyses of 263 patients with laryngeal leukoplakia]

Objective: To investigate the etiology, clinical and pathological characteristics of laryngeal leukoplakia and the predictive risk factors of recurrence and malignant transformation. Methods: Clinical data of 263 patients with laryngeal leukoplakia between January 2000 and December 2015 were analyzed retrospectively. Results: The pathological diagnoses included squamous epithelial hyperplasia (54.4%), mild dysplasia (17.9%), moderate dysplasia (12.2%), severe dysplasia and carcinoma in situ (12.5%), and invasive carcinoma (3.0%). Age and the extent of lesion were statistically different among different pathological groups (P<0.05). Gender, smoking and alcohol consumption did not show statistical differences among different pathological groups (P>0.05). Follow-up of 215 patients, excluding 6 cases of invasive carcinoma. The recurrence rate was 20.6%(43/209), and the malignant transformation rate was 5.3%(11/209). Multivariate analysis showed that pathological classification of moderate to severe dysplasia was the independent risk factor for recurrence and malignant transformation of laryngeal leukoplakia (P<0.05). In patients with severe dysplasia and carcinoma in situ, the recurrence proportion of conservative treatment, vocal cords (partial) resection and radiotherapy were 8/10, 0/10 and 2/11 respectively. Conclusions: Laryngeal leukoplakia occurs frequently in elderly men with long-term smoking history. Pathological diagnoses are different. The grade of dysplasia is the predictive risk factor for the recurrence and malignant transformation of laryngeal leukoplakia. More aggressive treatment and closer follow-up should be warranted for patients with moderate dysplasia, severe dysplasia and carcinoma in situ.

[Laryngeal endoscopic cricopharyngeal myotomy for cricopharyngeal achalasia post stroke]

Objective: To explore the safety and validity of endoscopic cricopharyngeal myotomy in patients with cricopharyngeal achalasia. Methods: A total of 19 patients with cricopharyngeal achalasia suffered from sustained dysphagia were enrolled in this study. The patients were divided into transcervical cricopharyngeal myotomy(CPM) group and endoscopic CPM (ECPM) group. Swallowing function and complications were evaluated.SPSS7.0 software was used to analyze the data. Results: The swallowing function improved significantly in seven patients in ECPM group, and 9 patients improved in CPM group.The video fluoroscopic swallowing study(VFSS)-swallowing score, VFSS-aspiration score and drinking test score were (3.1±1.1), (3.4±0.8) and (2.0±0.6)in post-ECPM, (3.4±1.4), (3.0±0.9) and (2.2±0.6)in post-CPM. No statistical difference was found in validity between CPM group and ECPM group(t=-0.435, t=1.086, t=-0.607, P>0.05). No statistical difference was observed on the occurrence of complication between two groups. Only one patient had subcutaneous emphysema after operation in ECPM. Conclusions: New surgical instruments and endoscopic surgical technique were safe and effective for cricopharyngeal achalasia. Because these instruments are cheaper, laryngeal endoscopic cricopharyngeal myotomy is easier to be popularized more easily than microscopic laser assistted CPM.

[Transoral endoscopic minimally invasive surgery for hypopharyngeal postcricoid and upper esophageal lesions]

Objective:To describe the therapeutic effect of transoral endoscopic minimally invasive surgery for hypopharyngeal postcricoidarea and upper esophageal lesions. Method:Transoral endoscopic minimally invastive surgery was carried out in fifteen patients.There were 7 patients with primary tumors on the postcricoid area, including three squamous cell carcinoma（2 cases T2N0M0，1 case T2N2cM0），two cavernous hemangioma, one giant fibrovascular polyp and one recurrent lipofibroma. The transoral endoscopic tumors resection en bloc was performed in all of them. Adjuvant postoperative radiation therapy was applied in cases of cancer, and bilateral neck dissections was performed in the T2N2cM0 case; There were other eight patients with upper esophageal lesions , seven cases dysphagia was caused by stroke and one case was Zenker diverticulum, treated by endoscopic cricopharyngeal myotomy ordiverticulotomy. Result:The en bloc resection endoscopically was achieved in all of patients with tumors on the postcricoid area. All surgical resection margins were negative.The two cases of postcricoid cancer and four benign tumor were followed up 16-30 months and 2-12 months respectively, and all of the cases were not local recurrence. A recent patient with postcricoid cancer had not finished postoperative adjuvant radiation therapy. The endoscopic cricopharyngeal myotomy was effective in 4 out of 7 patients,nasogastric feeding was no longer required.Significant improvement occurred in Zenker diverticulotomy patient, due to the return of physiological deglutition, and Barium swallow study showing disappearance of the diverticulum after one month.The effects of minimally invasive threatment were satisfactory,such as not need tracheotomy and early oral feeding, shorter hospital stay and less postoperative complications. Conclusion:Transoral endoscopic surgery is minimally invastive, safe and effective treatment alternative for some hypopharyngeal postcricoid area and upper esophageal lesions.

Optimization of Chlorella vulgaris and bioflocculant-producing bacteria co-culture: enhancing microalgae harvesting and lipid content

Microalgae are a sustainable bioresource, and the biofuel they produce is widely considered to be an alternative to limited natural fuel resources. However, microalgae harvesting is a bottleneck in the development of technology. Axenic Chlorella vulgaris microalgae exhibit poor harvesting, as expressed by a flocculation efficiency of 0·2%. This work optimized the co-culture conditions of C. vulgaris and bioflocculant-producing bacteria in synthetic wastewater using response surface methodology (RSM), thus aiming to enhance C. vulgaris harvesting and lipid content. Three significant process variables- inoculation ratio of bacteria and microalgae, initial glucose concentration, and co-culture time- were proposed in the RSM model. F-values (3·98/8·46) and R(2) values (0·7817/0·8711) both indicated a reasonable prediction by the RSM model. The results showed that C. vulgaris harvesting efficiency reached 45·0-50·0%, and the lipid content was over 21·0% when co-cultured with bioflocculant-producing bacteria under the optimized culture conditions of inoculation ratio of bacteria and microalgae of 0·20-0·25, initial glucose concentration of <1·5 kg m(-3) and co-culture time of 9-14 days. This work provided new insights into microalgae harvesting and cost-effective microalgal bioproducts, and confirmed the promising prospect of introducing bioflocculant-producing bacteria into microalgae bioenergy production.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work optimized the co-culture conditions of microalgae (C. vulgaris) and bioflocculant-producing bacteria (F2, Rhizobium radiobacter) in synthetic wastewater using response surface methodology, aiming to enhance C. vulgaris harvesting and lipid produced content. Bioflocculant-producing microbes are environmentally friendly functional materials. They avoid the negative effects of traditional chemical flocculants. This work provided new insights into microalgae harvesting and cost-effective production of microalgal bioproducts, and confirmed the promising prospect of introducing bioflocculant-producing bacteria into microalgae bioenergy production.

Hypertonic saline reduces lipopolysaccharide-induced mouse brain edema through inhibiting aquaporin 4 expression

INTRODUCTION

Three percent sodium chloride (NaCl) treatment has been shown to reduce brain edema and inhibited brain aquaporin 4 (AQP4) expression in bacterial meningitis induced by Escherichia coli. Lipopolysaccharide (LPS) is the main pathogenic component of E. coli. We aimed to explore the effect of 3% NaCl in mouse brain edema induced by LPS, as well as to elucidate the potential mechanisms of action.

METHODS

Three percent NaCl was used to treat cerebral edema induced by LPS in mice in vivo. Brain water content, IL-1β, TNFα, immunoglobulin G (IgG), AQP4 mRNA and protein were measured in brain tissues. IL-1β, 3% NaCl and calphostin C (a specific inhibitor of protein kinase C) were used to treat the primary astrocytes in vitro. AQP4 mRNA and protein were measured in astrocytes. Differences in various groups were determined by one-way analysis of variance.

RESULTS

Three percent NaCl attenuated the increase of brain water content, IL-1β, TNFα, IgG, AQP4 mRNA and protein in brain tissues induced by LPS. Three percent NaCl inhibited the increase of AQP4 mRNA and protein in astrocytes induced by IL-1β in vitro. Calphostin C blocked the decrease of AQP4 mRNA and protein in astrocytes induced by 3% NaCl in vitro.

CONCLUSIONS

Osmotherapy with 3% NaCl ameliorated LPS-induced cerebral edema in vivo. In addition to its osmotic force, 3% NaCl exerted anti-edema effects possibly through down-regulating the expression of proinflammatory cytokines (IL-1β and TNFα) and inhibiting the expression of AQP4 induced by proinflammatory cytokines. Three percent NaCl attenuated the expression of AQP4 through activation of protein kinase C in astrocytes.

Insulin-like growth factor-1 receptor signaling in 3T3-L1 adipocyte differentiation requires lipid rafts but not caveolae

Previously, we have found that lipid rafts/caveolae were essential for insulin-like growth factor-1 (IGF-1) receptor signaling during 3T3-L1 preadipocytes differentiation induction. However, it was not identified as to which of the membrane lipid-ordered microdomains mediates the receptor signal. Using small double-stranded RNA-mediated interference (RNAi), we successfully suppressed the caveolin-1 protein expression. In cells stably transfected with vector expressing small interfering RNA (siRNA) fragment, no caveolin-1 protein or caveola was detected. On the other hand, removal of caveolin-1 did not affect the caveolinless lipid rafts or the localization of IGF-1 receptor in lipid rafts on plasma membrane. IGF-1 receptor signal transduction and induced cellular differentiation were normal in RNAi cells with only lipid rafts. Furthermore, these IGF-1 receptor signaling events were still sensitive to the cholesterol-binding reagents. Thus, our results suggest that lipid rafts are sufficient for IGF-1 receptor signaling and the recruitment of signal molecules by caveolin-1 is not essential for IGF-1 receptor signaling.

[Detection of circulating antigen in serum and cerebrospinal fluid for diagnosis of cerebral cysticercosis]

AIM

To detect circulating antigen(CAg) in serum and cerebrospinal fluid(CSF) from patients with cerebral cysticercosis with specific antiserum by sandwich ELISA.

METHODS

Antisera were prepared from rabbits immunized respectively with 3 antigens with molecule weights of 64 kDa, 53 kDa, 32 kDa-30 kDa extracted from Cysticercus cellulosae and purified by SDS-PAGE.

RESULTS

When samples from patients were tested with antiserum against 53 kDa antigen, the CAg positive rate was 93.8% in serum and 91.7% in CSF of 32 patients with active cysticercosis, whereas only one positive was found in CSF in 16 patients with inactive cysticercosis. The detection rate of CAg was significantly higher with anti-53 kDa antiserum than with anti-64 kDa and anti-32 kDa-30 kDa antiserum.

CONCLUSION

Sandwich-ELISA using antiserum against 53 kDa antigen to detect CAg was found to be a promising assay for diagnosis and evaluation of treatment efficacy of active cerebral cysticercosis in terms of its high sensitivity and specificity.

[Study on the characters of hydrogen bonds in protein and nucleic acid of the breast cancer tissues]

Some remarkable spectral differences are observed between the normal breast tissues and breast cancer tissues, including those of association pattern and degree of the hydrogen bonds in the protein and nucleic acid biomacromolecules. These differences are found in the relative intensity, absorption position and shape of the characteristic bands: (1) amide I band, stretching vibration bands of N-H group and C-O(H) in the residues of some amino-acids, and (2) the relative intensity of asymmetric stretching vibration of the phosphodiester group in nucleic acid. The hydrogen bond is the major force which maintain and promote the formation of the high structure of protein and nucleic acid. It is possible to diagnose the breast cancer and forecast the possibility of canceration using above spectral characters of the hydrogen bond with other spectral characters.

C3G, a guanine nucleotide exchange factor bound to adapter molecule c-Crk, has two alternative splicing forms

Two types of C3G cDNA were isolated from mouse 3T3-L1 adipocyte cDNA library. A 114-bp sequence in the middle of C3G cDNA is deleted in the short type cDNA. By RT-PCR analysis, it was found that these two types of C3G mRNA existed in all the mouse tissues. Sequence comparison revealed 88% nucleotide sequence identity between mouse and human C3G cDNA. Comparison of mouse C3G cDNA with the human genome database suggested that this 114-bp sequence comprised an entire exon, and it is confirmed by PCR analysis using mouse genomic DNA and cDNA template. These results indicate that two C3G mRNAs and proteins result from alternative RNA splicing.

Cobalt chloride induces PC12 cells apoptosis through reactive oxygen species and accompanied by AP-1 activation

Reactive oxygen species (ROS) are supposed to play an important role in hypoxia- and ischemia/reperfusion-mediated neuronal injury with the characteristics of apoptosis. There are many reports showing that cobalt chloride (CoCl(2)) could mimic the hypoxic responses in some aspects including production of ROS in cultured cells. The cytotoxicity of CoCl(2) and its molecular mechanisms have yet to be elucidated. We report that CoCl(2) triggered neuronal PC12 cells apoptosis in a dose- and time-dependent manner. Apoptosis was demonstrated by morphological changes and DNA fragmentation, and was dependent on macromolecular synthesis. Apoptosis was also confirmed by the decrease of the expression of Bcl-X(L). To our knowledge, this is the first documentation of the apoptotic induction of CoCl(2) on PC12 cells. Furthermore, ROS production in PC12 cells was increased during CoCl(2) treatment. Antioxidants, which could inhibit ROS production, significantly blocked CoCl(2)-induced apoptosis, suggesting that apoptosis is mediated by ROS production. We also observed a significant increase of the DNA-binding activity of AP-1 in response to CoCl(2) and this increase was blocked by antioxidants, showing that CoCl(2)-induced apoptosis is accompanied by ROS-activated AP-1. CoCl(2)-treated PC12 cells may serve as an in vitro model for studies of molecular mechanisms in ROS-linked neuronal disorders.

Critical sites for the interaction between IL-2Rgamma and JAK3 and the following signaling

JAK3 is the only known protein tyrosine kinase associating with IL-2Rgamma. This interaction is supposed to be very important to IL-2 signaling. In order to identify the critical residues for these two molecular interactions and the following signal events, various mutants of gammac and JAK3 were constructed on the basis of computer analysis. The direct interaction was determined via the yeast two-hybrid system, while the signaling was analyzed with reporter genes under the control of the c-fos, c-myc, or tnf-beta promoters, respectively. Results showed that there are two key sites on gammac involved in this interaction and the following signal transduction: the critical one is E327 via electrostatic interaction, the other is L293 via hydrophobic interaction. As to JAK3, the data indicated that Y100 is important for the interaction with gammac. These results also document that the requirement for interaction between gammac and JAK3 is different to activate different signaling pathways mediated by gammac, such as c-fos, c-myc, and JAK-STAT.

Alphamethrin-impregnated bed nets for malaria and mosquito control in China

A community-based intervention trial was carried out to evaluate the effectiveness of alphamethrin-impregnated bed nets for control of Plasmodium vivax malaria and its vector in an area of moderate endemicity in southern Henan province, central China in 1990. Malaria incidence was significantly lower in the intervention group than in the comparison group (2.03 vs. 3.57 per 100 person-years at risk). The protective efficacy for malaria incidence was 43%. The prevalence of malaria parasitaemia among children under 10 years old in the intervention group was about one-quarter of that in the comparison group (0.93% vs. 3.25% and 0.71% vs. 1.96% after one and 4 months use of impregnated nets, respectively). Alphamethrin-impregnated bed nets had a mass killing effect on vector mosquitoes. The outdoor person-biting density of Anopheles anthropophagus and A. sinensis decreased by 70.3% and 29.3% respectively. The density of these 2 mosquito species found resting inside treated nets was close to zero. No side effect was found among users of impregnated bed nets. Impregnation with alphamethrin was more effective on polyester than on cotton netting and residual effects lasted at least one year. Use of alphamethrin is less expensive than permethrin and deltamethrin.

The protective effect of bed nets impregnated with pyrethroid insecticide and vaccination against Japanese encephalitis

A population-based case-control study to evaluate the protective effect of bed nets impregnated with pyrethroid insecticide and of vaccination against Japanese encephalitis was carried out in Gusi county, Henan province, China from June to September 1991; 50 cases and 100 matched controls were studied. Bed nets impregnated with pyrethroid insecticide greatly decreased the risk of infection among children under 10 years old, and vaccine efficacy was 78% (95% CI 16%-94%). We suggest that impregnated bed nets could be used as a quick response during outbreaks of Japanese encephalitis.

The effect of DDT spraying and bed nets impregnated with pyrethroid insecticide on the incidence of Japanese encephalitis virus infection

A retrospective investigation was conducted to evaluate the effectiveness of DDT residual indoor spraying and bed nets impregnated with pyrethroid insecticide for Japanese encephalitis control in southern Henan province, China. DDT residual indoor spraying had no effect on the incidence of Japanese encephalitis, but it was greatly reduced after the introduction of pyrethroid-impregnated bed nets. Only a small effect on outdoor biting densities of Culex tritaeniorhyncus was found, although the number of mosquitoes resting inside bed nets decreased markedly after the introduction of bed net impregnation.