[Establishment and verification of invasion syndrome prediction model in patients with diabetes complicated with Klebsiella pneumoniae liver abscess]

Objective: To analyze the correlative factors of invasion syndrome in patients with diabetes complicated with Klebsiella pneumoniae liver abscess, and to construct and verify the online nomographic prediction model. Methods: A case control study. The clinical data of 213 diabetic patients with Klebsiella pneumoniae liver abscess admitted to the Third Affiliated Hospital of Soochow University from January 1, 2015 to December 31, 2021 were retrospectively analyzed. The patients were divided into the training set (149 cases) and the test set (64 cases) by stratified random sampling method at a ratio of 7∶3. Synthetic minority over-sampling technique(SMOTE) was used to process the imbalanced data, then Lasso regression was used to screen out the optimal feature variables in the training set and multivariate logistic regression model was used to construct the prediction model of invasion syndrome in patients with diabetes complicated with Klebsiella pneumoniae liver abscess, and verify it in the training set and test set. Receiver operating characteristic (ROC) curve, calibration curve and decision curve analysis (DCA) were used to evaluate the prediction efficiency of the model, and the simple and online interactive dynamic web page column graph was constructed. Results: Among the 213 patients, 60 were males and 153 were females, aged of (61.4±12.0) years. A total of 25(11.74%) diabetic patients with Klebsiella pneumoniae liver abscess developed invasion syndrome, which were included in divided into invasive K.pneumoniae liver abscesses syndrome (IKPLAS) group, and the other 188 cases were in without invasive K.pneumoniae liver abscesses syndrome (NIKPLAS) group. SMOTE algorithm was used for oversampling processing, so that the ratio of positive and negative samples was 1∶1. In the oversampling training set, 5 main risk factors were screened based on Lasso regression, namely fasting blood glucose (λ=0.063), hemoglobin (λ=-0.042), blood urea nitrogen (λ=-0.050), abscess size (λ=-0.025) and sequential organ failure assessment (SOFA) score (λ=0.450), respectively. Multivariate logistic regression model showed that fasting blood glucose (OR=1.20, 95%CI: 0.98-1.48, P=0.006), hemoglobin (OR=0.90, 95%CI: 0.86-0.95, P<0.001), blood urea nitrogen (OR=1.22, 95%CI: 1.03-1.43, P=0.017), abscess diameter (OR=0.76, 95%CI: 0.61-0.94, P=0.010), SOFA score (OR=3.08, 95%CI: 2.18-4.36, P<0.001) were associated with invasion syndrome in patients with diabetes complicated with Klebsiella pneumoniae liver abscess. The area under the curve of ROC in the training set was 0.966 (95%CI: 0.943-0.989), the sensitivity was 90.5%, and the specificity was 91.3%. The area under the curve of the validation set ROC was 0.946 (95%CI: 0.902-0.991), with a sensitivity of 79.6% and a specificity of 88.9%. The calibration curves drawn in the training set and the test set fit well with the ideal curve. DCA showed that the neomorph prediction model had a good clinical net benefit when predicting the risk of IKPLAS in patients with diabetes complicated with Klebsiella pneumoniae liver abscess was 0.10-0.40. Conclusions: Fasting blood glucose, hemoglobin, urea nitrogen, abscess size and SOFA score are the related factors for invasion syndrome in patients with diabetes complicated with Klebsiella pneumoniae liver abscess. The constructed column graph can effectively predict the risk of invasion syndrome in patients with diabetes complicated with Klebsiae pneumoniae liver abscess.

Primary pulmonary hyalinising clear cell carcinoma: Two cases and literature review

Hyalinising clear cell carcinoma (HCCC) of the lung is an extremely rare tumour that is just recently recognised as one of the salivary gland-type tumours (SGTT) in the latest WHO classification of thoracic tumours. Eleven cases have been reported in English literature since Joaquín et al. reported the first case. Given the very limited number of cases, the clinical and histological features of pulmonary HCCC are equivocal. Herein, we present two cases of pulmonary HCCC. The patients were a 66-year-old man and a 48-year-old woman. The mass was located on the right main bronchus and right middle lobar bronchus separately. One was 2 cm and the other was 3.3 cm in the greatest dimension. The tumours were comprised of small monomorphic cells with clear or eosinophilic cytoplasm and infiltrated in a hyalinising stroma arranged in nests, cords, sheets and trabeculae. Their morphology resembled their head and neck counterparts. Immunohistochemically, the tumour cells were positive for AE1/AE3, P63, while negative for TTF1, Calponin, S-100, HMB45 and PAX8. Ki-67 labeling ranges from 3% to 10%. Fluorescence in situ hybridisation (FISH) demonstrated EWSR1 rearrangement and Next-generation sequencing (NGS) demonstrated EWSR1- ATF1 (exon 11: exon 3) fusion in case one and EWSR1- ATF1 (exon 2: exon 12) fusion in case two. This is the first time to report the EWSR1-ATF1fusion point other than exon 11: exon 3 in pulmonary HCCC. Case one recurred two years after local resection but didn't metastasise during follow-up 36 months. Case two is alive without disease after lobectomy during follow-up 14 months.

Single-Cell RNA Sequencing Reveals the Immune Cell Profiling in IMQ Induced Psoriasis-Like Model

PURPOSE

Psoriasis is a chronic systemic inflammatory skin disease with a high recurrence rate. The immune response plays an important role in psoriasis. However, the subsets of immune cells involved in inflammation in psoriatic mice have not been fully studied. This study showed the immune environment characteristics of psoriasis in mice.

METHODS

We used single-cell RNA sequencing (10× Genomics) as an unbiased analytical strategy to investigate the heterogeneity of skin immune cells in imiquimod-induced psoriasis mice systematically.

RESULTS

We identified 10 major clusters and their marker genes among 14,439 cells. The proportions of macrophages, NK/T cells, conventional dendritic cells (cDCs) and plasmacytoid dendritic cells (pDCs) were increased in psoriatic mice. Macrophages were the largest group and were further divided into 7 subgroups, and all macrophage clusters were increased in psoriatic mice. Differentially expressed genes in control versus psoriatic mice skin lesions showed that Fcgr4, Saa3 and Acp5 in macrophages, Acp5, Fcgr4 and Ms4a6d in NK/T cells, Saa3 in cDCs, and Ifitm1 in pDCs were upregulated in psoriasis mice. Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis emphasized the role of oxidative phosphorylation signals and antigen processing and presentation signals in murine psoriasis-like models.

CONCLUSION

Our study reveals the immune environment characteristics of the commonly used IMQ induced psoriasis-like models and provides a systematic insight into the immune response of mice with psoriasis, which is conducive to comparing the similarities and differences between the mouse model and human psoriasis.

[Whole genomic copy number variation score: an indicator of potential diagnostic and prognostic value for lung adenocarcinoma]

Objective: To verify the value of whole genomic copy number variation (WGCNV) detection and scoring system in the diagnosis and prognosis of lung adenocarcinoma. Methods: Seventy-six lung adenocarcinoma specimens including ninety-one tumor samples and twenty adjacent non-tumor lung tissue samples were collected using Laser capture microdissection (LCM). Whole genomic amplification (WGA) was used to enrich DNA and construct a sequencing library for next generation sequencing (NGS). Changes of larger than 5Mb CNV in this study were analyzed and scored. The nuclear grading and score of tumor cells in the surgery and pleural effusion cytology of lung adenocarcinoma specimens were evaluated separately. For each case, we evaluated (1) nuclear size, (2) mitotic counts, (3) nuclear atypia, (4) atypical mitoses. The data of disease-free survive (DFS) and overall survive (OS) were collected for assessing the prognostic value of WGCNV score. Meanwhile, receiver operating characteristic (ROC) and area under curve (AUC) were used to define a cut-off value and evaluate the diagnostic significance in lung adenocarcinoma. Results: The WGCNV scores of twenty adjacent non-tumor lung tissue samples were treated as normal control and all of WGCNV scores of tumor samples range from 0 to 9.95, the median score was 2.7. The WGCNV scores were divided into three groups: low score group <1.74, medium score grade 1.74~4.23, high score grade >4.23. The WGCNV score was positively associated with the nuclear grade scoring (r=0.780 90, P<0.001). The result for evaluation of prognostic value of the WGCNV scores showed that comparing with low WGCNV score group, Hazard Ratio (HR) of medium score group was 4.11 (95%CI=0.72~23.57) and high score group was 2.07 (95%CI=0.30~14.12). These results suggested that the risks of the medium and high WGCNV score group elevated. According to the analysis results of ROC curve, when the cut off value was 0.01, the sensitivity and specificity for lung adenocarcinoma diagnosis were 97.8% and 95.0% respectively, the positive predictive value (PPV) and negative predictive value (NPV) were 99.0% and 90.1%, respectively, the AUC was 0.981. In the differentiation of adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) group and invasive adenocarcinoma group, when the cut off value was 1.8, the sensitivity and specificity between the two groups were 78.1% and 94.4%, and the PPV and NPV were 98.0% and 52.0%, respectively, the AUC was 0.896. Conclusion: This study verifies that WGCNV scoring system has a potential diagnostic and prognostic value in lung adenocarcinoma.

ILK participates in renal interstitial fibrosis by altering the phenotype of renal tubular epithelial cells via TGF-β1/smad pathway

OBJECTIVE

To explore the specific role of ILK (integrin-linked kinase) in regulating renal fibrosis and its underlying mechanism.

MATERIALS AND METHODS

NRK-52E cells were induced by transforming growth factor-β1 (TGF-β1) for observing phenotype change. Renal tubular epithelial cell marker, fibrosis marker and expression level of ILK in NRK-52E cells were also detected. After overexpression of ILK, phenotype change of NRK-52E cells was observed. For in vivo experiments, we constructed UUO (unilateral ureteral obstruction) model in CD1 mice. Renal tubular epithelial cell marker, fibrosis marker and expression level of ILK in UUO mice were detected. The regulatory effect of ILK on renal fibrosis was detected after injection of ILK overexpression plasmid. Western blot was performed to detect related genes in the TGF-β1/smad pathway.

RESULTS

Accompanied by the TGF-β1-induced phenotype change in NRK-52E cells, both mRNA and protein levels of ILK were upregulated. Overexpression of ILK remarkably stimulated the phenotype change in NRK-52E cells. Similarly, ILK was highly expressed in UUO mice. Renal fibrosis was aggravated after injection of ILK overexpression plasmid in UUO mice. Western blot results showed that expressions of p-smad3 and smad3 were upregulated during the process of renal fibrosis.

CONCLUSIONS

ILK is upregulated during the process of renal fibrosis. ILK participates in the development of renal fibrosis by altering phenotypes of renal tubular epithelial cells via a TGF-β1/smad pathway.

Diagnostic and prognostic significance of long noncoding RNA SSTR5-AS1 in patients with gastric cancer

OBJECTIVE

Long noncoding RNAs (lncRNAs) display a functional effect on the pathogenesis of several diseases, including various tumors. Herein, we aimed to reveal the role of lncRNA somatostatin receptor 5 antisense RNA 1 (SSTR5-AS1) in gastric cancer (GC).

PATIENTS AND METHODS

qRT-PCR was utilized for testing the SSTR5-AS1 expression in 158 paired primary GC tissues and corresponding normal gastric specimens. Receiver operating characteristic (ROC) curves were established to determine the diagnostic values of overexpression of SSTR5-AS1 in GC. A chi-square test was performed to analyze the correlation between SSTR5-AS1 expressions and several clinicopathological features in GC patients. Kaplan-Meier survival curve was constructed to estimate the overall survival (OS) and disease-free survival (DFS). Multivariate analyses were conducted to examine the prognostic value of SSTR5-AS1.

RESULTS

We observed that SSTR5-AS1 expression was highly expressed in GC specimens compared with adjacent non-tumor specimens (p < 0.01). High SSTR5-AS1 expression was correlated with an advanced pathologic stage. The ROC curves showed that areas under the ROC curve (AUC) for SSTR5-AS1 is 0.8419. Moreover, high expression of SSTR5-AS1 was observed to be associated with distant metastasis (p = 0.021) and TNM stage (p = 0.042). Besides, survival analysis showed that GC patients with high SSTR5-AS1 expression suffered poorer OS (p = 0.020) and DFS (p = 0.0007). Multivariate assays demonstrated that increased expressions of SSTR5-AS1 could be an independent prognostic marker of OS and DFS of GC patients.

CONCLUSIONS

Our findings indicate that SSTR5-AS1 served as a promising novel prognostic biomarker for GC.

Elevated aerobic glycolysis in renal tubular epithelial cells influences the proliferation and differentiation of podocytes and promotes renal interstitial fibrosis

OBJECTIVE

The aim of this study was to elaborate the influence of changing energy metabolism pattern of renal tubular epithelial cells in the process of renal interstitial fibrosis on podocytes. Meanwhile, we also investigated the relationship between energy metabolism pattern and the development of renal interstitial fibrosis.

MATERIALS AND METHODS

We established a model of renal interstitial fibrosis by unilateral ureteral obstruction (UUO). The protein and messenger RNA (mRNA) expression of fibrosis signs, such as α-smooth muscle actin (α-SMA) and fibronectin (FN) were detected. We also measured the protein and mRNA expression of key glycolytic enzymes, including pyruvate kinase muscle isozyme 2 (PKM2) and human glandular kallikrein 2 (HK2). The proliferation and differentiation of podocytes during fibrosis were observed by monitoring the expression of nephrin and myocardin. In vitro experiments, primary podocytes were extracted, cultured, and stimulated with lactate. Then the alterations during the process were observed. Finally, PKM2 expression was inhibited by intravenous infusion of the plasmid. The link between the expression of marker protein as well as differentiation protein in podocytes and renal interstitial fibrosis was analyzed.

RESULTS

During the process of renal interstitial fibrosis, phenotypic changes and enhanced expression of fibrosis and proliferation markers were found in fibroblasts. Meanwhile, in renal tubular epithelial cells, increased expression of key enzymes of glycolysis, the level of glycolysis as well as lactate metabolites cooperatively led to hypoxic and acidic environment, eventually inhibiting the proliferation and differentiation of podocytes and aggravating fibrosis. When the level of glycolysis in renal tubular epithelial cells was reduced, the number and function of podocytes were partially restored, and renal interstitial fibrosis was alleviated.

CONCLUSIONS

During renal interstitial fibrosis, glycolysis of renal tubular epithelial cell was increased, leading to the recodification of energy metabolism. This process affected the number and function of podocytes and aggravated renal interstitial fibrosis.

[Evaluation of Consistency in detection of epidermal growth factor receptor gene T790M mutation in plasma and tumor specimens of patients with lung adenocarcinoma]

Objective: To evaluate the consistency in detection of T790M mutation of epidermal growth factor receptor gene (EGFR) in plasma and tumor samples of patients with lung adenocarcinoma. Methods: The tumor tissues or cytological specimens of 12 patients with operable lung adenocarcinoma(stage Ⅰ-ⅢA) and 100 patients with advanced stage ⅢB-Ⅳ lung adenocarcinoma were collected, among which 11 patients showed acquired resistance for gefitinib (11/100). In the same period, peripheral blood samples were collected from all patients and 50 healthy volunteers. Amplification refractory mutation system (ARMS) was used to detect EGFR mutations in tumor specimens. Next Generation Sequencing(NGS) based circulating single-molecule amplification and resequencing technology (cSMART)was performed to quantitatively detect the EGFR mutations in circulating tumor DNA (ctDNA) from plasma specimens. Results: The sensitivity, specificity and concordance rate of EGFR T790M mutation between plasma and tissue specimens from 100 advanced stage patients were 50.0%, 72.9% and 72.0%, respectively. For L858R mutation and exon 19 deletion mutations, the above mentioned sensitivity, specificity and concordance rate were 91.7%, 100.0%, and 98.0%, as well as 79.2%, 100.0% and 95.0%, respectively. The L858R mutation and exon 19 deletion mutations were not detected in plasma of 50 healthy volunteers, whereasT790M mutation(1.0±0.0 copies) was found in 7 individuals(7/50, 14.0%). Similarly, in 12 resectable patients, 4 (4/12, 33.3%) T790M mutations were found in plasma (1.2±0.2 copies), but no L858R mutation and 19 exon deletion mutations. In comparison, 28.0% of patients with advanced lung adenocarcinoma (28/100)had detectable T790M mutation in plasma with copy numbers (34.0±22.7 copies). Furthermore, the copy numbers of T790M were 268.2±119.9 in plasma of 5 cases with acquired gefitinib-resistance. Conclusions: In patients with advanced stages of lung adenocarcinoma, the detection of T790M mutation in plasma and tumor specimens is low. The T790M mutation also exists in the plasma of some healthy controls, suggesting that T790M mutation participates in EGFR signaling pathway and it might function in healthy population.

Comparative study of 13 candidate genes applying multi-reference normalization to detect the expression of different fineness in skin tissues of wool sheep

Fiber diameter is a useful indicator of wool traits and it is the main determinant of wool quality and value. A comparative study was conducted to analyze the abundance and expression of 13 candidate genes using expression profile microarray analysis and to identify novel molecular markers associated with wool traits to provide a molecular basis for improving wool quality in sheep. Genes associated with fineness of skin tissue were identified using a real-time reverse transcriptase-polymerase chain reaction method with 18SrRNA, β-Actin, and GAPDH used for multi-reference normalization. The results indicated that the expression levels of TXNIP, TFDP1, and FAIM genes in super-fine type wool sheep were higher than those in fine-type wool sheep; the corresponding expression ratios of super-fine to fine wool sheep were 1.45, 1.57, and 2.55, respectively. The expression levels of PIK3CA, ADAM9, and FZD3 genes were lower in super-fine wool sheep compared with fine-type wool sheep; the corresponding expression ratios were 0.61, 0.65, and 0.52, respectively. The other genes tested (RPS6KA, ABCG2, GSTA1, PTPN13, GJB3, PPARD, and LAMB1) were similarly expressed in both types of wool sheep. These results infer that lower expression of PIK3CA, ADAM9, and FZD3 genes was associated with lower fiber diameter, whereas lower expression of TXNIP, TFDP1, and FAIM genes was associated with higher fiber diameter.

[Cytology of basaloid squamous cell carcinoma and small cell carcinoma of lung: a comparative study]

OBJECTIVE

To evaluate the roles of cytomorphology and immunohistochemistry in distinguishing between basaloid squamous cell carcinoma (BSC) and small cell carcinoma (SCC) of lung.

METHODS

The direct smears and/or liquid-based cytology preparation (ThinPrep) of bronchial brushing/washing and fine-needle aspiration (FNA) specimens from 17 cases of biopsy-proven BSC of lung were retrospectively reviewed and compared with those from 17 cases of SCC. The cytomorphologic parameters analyzed included proportion of cohesive cell clusters, cell palisades/rosettes, adenoid cystic features, crushing artifact, nuclear maximum diameter, nuclear molding, scantiness of cytoplasm,"salt-and-pepper"nuclei, distinct nucleoli, spindly configuration, individual cell keratinization, necrosis, hyaline material, apoptosis and mitotic activity. Immunocytochemical/immunohistochemical study of 25 cases was performed. Ten FNA samples of basaloid squamous cell carcinoma were also analyzed for epidermal growth factor receptor mutations in exons 18, 19, 20 and 21 using amplification refractory mutation system.

RESULTS

Most of the 17 BSC cases (15/17) showed a predominance of tightly cohesive tumor cell clusters. The proportion of isolated tumor cells was high in SCC (more than 60% in 14 cases). The nuclear maximum diameter of BSC was slightly larger than that of SCC (9 to 11 μm in BSC versus 7 to 9 μm in SCC)."Salt-in-pepper"nuclei, nuclear molding and crushing artifact were detected in all SCC cases (15/17, 17/17 and 14/17, respectively). These features were only occasionally found in BSC group. Nucleoli were present in BSC and rarely (2/17) in SCC. Only 9 of 17 BSC cases showed individual cell keratinization. The differences in the above-mentioned cytomorphologic features were statistically significance (P<0.05). The results of immunohistochemistry performed on the cell block sections and immunocytochemistry performed on the ThinPrep slides were identical to that performed on the corresponding biopsy specimens. The tumor cells in BSC were consistently positive for CK5, p40 and p63. TTF1, chromogranin A, synaptophysin and CD56 were positive in most of SCC. One of SCC cases showed focal PAX5 expression. No EGFR mutations were detected in the 10 BSC cases studied.

CONCLUSIONS

Selected cytomorphologic features, including presence of cohesive cell clusters, larger nuclear size, distinct nucleoli, lack of crushing artifact, absence of nuclear molding and presence of individual cell keratinization, are helpful in diagnosing BSC on cytology specimens. Immunohistochemistry using a panel of TTF1, CK5, p40/p63 and chromogranin A/synaptophysin/CD56 provides further clues in differential diagnosis between BSC and SCC. EGFR mutation study is often negative in lung BSC.

Jagged-1-HES-1 signaling inhibits the differentiation of TH17 cells via ROR gammat

Notch signaling plays an important role in differentiation of T cells. However, little is known as to action of it in differentiation of Th17 cell subset. In this study, a soluble Jagged-1/Fc chimera protein (Jagged-1) was directly used to activate Jagged-1-Notch signaling, while Hes-1-targeting siRNA was used to knock down Hes-1 gene to investigate effect of Jagged-1-Hes-1 signaling on the differentiation of CD4+ T cells into Th17 cells. The results showed that Jagged-1 could promote the expression of Hes-1 and Deltex-1 mRNAs and the expression of NICD, Hes-1 and Deltex-1 proteins, which might be significantly blocked by DAPT, a specific inhibitor of Notch signaling. Jagged-1-Hes-1 signaling resulted in the markedly decreased in situ expression of RORgammat in the CD4+ T cells induced by IL-6 plus TGF-ß. Flow cytometric analysis showed the reduction of IL-17 production in CD4+ T cells by Jagged-1, but the enhancement of it by Hes-1-targeting siRNA. The level of IL-10 produced by the treated cells was also enhanced, whereas the expression of IL-17 was prominently attenuated, which could be offset by anti-Jagged-1 antibody or DAPT. The results indicate that Jagged-1-Hes-1 signaling can suppress the skewing of CD4+ T cells toward Th17 cells via RORgammat, for which Hes-1 may be crucial.

Study of ceria-carbonate nanocomposite electrolytes for low-temperature solid oxide fuel cells

Composite and nanocomposite samarium doped ceria-carbonates powders were prepared by solid-state reaction, citric acid-nitrate combustion and modified nanocomposite approaches and used as electrolytes for low temperature solid oxide fuel cells. X-ray Diffraction, Scanning Electron Microscope, low-temperature Nitrogen Adsorption/desorption Experiments, Electrochemical Impedance Spectroscopy and fuel cell performance test were employed in characterization of these materials. All powders are nano-size particles with slight aggregation and carbonates are amorphous in composites. Nanocomposite electrolyte exhibits much lower impedance resistance and higher ionic conductivity than those of the other electrolytes at lower temperature. Fuel cell using the electrolyte prepared by modified nanocomposite approach exhibits the best performance in the whole operation temperature range and achieves a maximum power density of 839 mW cm(-2) at 600 degrees C with H2 as fuel. The excellent physical and electrochemical performances of nanocomposite electrolyte make it a promising candidate for low-temperature solid oxide fuel cells.

Reactivation of p53 by inhibiting Mdm2 E3 ligase: a novel antitumor approach

The p53 tumor suppressor has been pursued as a cancer therapeutic target based on its ability to induce cell cycle arrest and apoptosis. Reactivation of p53 in the approximately 50% of tumors that retain a functional p53 has served as potential approach in the development of cancer drug therapy. Mdm2 is a major negative regulator of p53 and has long been thought to inhibit p53 in two ways: through ubiquitination of p53, signaling for its degradation by the proteasome, and through directly binding to p53, masking its transactivation domain. Research on Mdm2 E3 function and regulation has important implications for the feasibility of targeting Mdm2 in cancer treatment. By targeting Mdm2 in cancers, especially those harboring wild-type p53, it may be possible to restore p53 function to control tumor growth. Several inhibitors for Mdm2 have been developed and have shown promise in restoring p53 function. This review will summarize the current progress of targeting Mdm2 in cancer treatment with a focus on regulating Mdm2 E3 ubiquitin ligase activity via a number of small Mdm2 binding proteins and the post-translational modification of Mdm2 itself. The potential of inhibitors of Mdm2 E3 ligase as a new novel class of anticancer drugs will also be discussed.

Structure and dynamics of polymer-grafted clay suspensions

The structure and dynamics of polymer-grafted two-dimensional silicate layers in solution were investigated. The geometry of the individual silicate layers was examined by looking at both polarized and depolarized light scattering from dilute solutions, while higher-concentration systems were used to study the interaction and dynamics of polymer-grafted silicate layers in suspension. The form factor for an oblate ellipsoid was used to fit the polarized intensity profile, and values of a approximately 80 nm and b approximately 380 nm for the semi-axes were obtained. The 80 nm value compares reasonably with the dimensions of the polymer brushes grafted on the surface of the silicate layers. The modulus of the grafted silicate in solution, as determined by Brillouin scattering, is of the order of 10 GPa. The cooperative diffusion mechanism, typical of interacting polymer chains, is suppressed due to the high polymer osmotic pressure. The osmotic pressure is also responsible for the weak interpenetration of the densely grafted polymer chains on the surface of the silicate layers. The scattering data indicates that the polymer-grafted nanoparticles move via collective diffusion and experience significant decrease in mobility above their overlap concentration.

Structure activity studies on group C meningococcal polysaccharide-protein conjugate vaccines: effect of O-acetylation on the nature of the protective epitope

A series of group C meningococcal polysaccharide-tetanus toxoid (GCMP-TT) conjugates were prepared as vaccines with varying percentages of O-acetylation at the C-7 and C-8 positions of sialic acid residues in the polysaccharide (PS). The immune response in mice was highly dependent on the degree of O-acetylation. Less O-acetylation resulted in higher serum bactericidal activity (SBA) towards the O-acetylated (OA) meningococcal strain, C11. In addition, since an unconjugated de-O-acetylated (dOA) GCMP vaccine was previously shown to be highly immunogenic in humans, we had chosen this dOA form to couple with TT by reductive amination for clinical evaluation. This conjugate vaccine was shown to be well-tolerated and highly immunogenic in adults, children, and infants in the UK. To understand the nature of the GCMP protective epitope, a series of spectroscopic and serological studies were conducted, using high resolution H-NMR spectroscopy at 500 MHz and competitive inhibition SBA assays. The dOA GCMP was 10-1000 times better at inhibiting the SBA for an OA strain than the OA GCMP, suggesting that the GCMP-based protective epitope on the bacterium exists in a dOA form. In addition, SBA for an OA strain is highly correlated with dOA GCMP-specific IgG. NMR data on freshly isolated GCMP indicated that, on the surface of the organism, most of the O-acetylation exists at position C-8, with some regions containing dOA or OA C-7 sialic acid. After extraction of PS and storage in solution, most of the O-acetyl groups migrate to C-7, leaving an epitope that is conformationally related, but not quite identical (due to the presence of the O-acetyl group), to the one contained in the dOA PS. We speculate that the role of the O-acetyl group at the C-8 position of the PS on the organism is to form less immunogenic epitopes, or mask the protective epitope, and thus escape immune surveillance. The dOA form of the vaccine may therefore provide better protection against group C meningococcal disease than the OA form by eliciting a greater proportion of functional antibodies that are directly aimed at the protective epitope.

[Flotation and extraction spectrophotometric determination of trace silicate in water]

In HCl solution, silicate reacted with molybdate ammonium to produce silicomolibdic, then a yellow compound which was produced from the oxidation of TMB was simultaneously isolated to benzene phase by flotation and then isolated to dimethylsulfoxideformic acid by extraction. The compound gives a high absorption at 458 nm. The apparent molar absorptivity is 1.26 x 10(5) L.mol-1.cm-1. In the range of 0.02-1 mg.L-1 Si obeys Beer's law. The proposed method which combines with enrichment and measurement is simple, rapid, selective and convenient to determine silicate in water with satisfied results.