Synthesis and properties of thermotropic polyesters modified with a non-mesogenic rigid group

Four series of copolyesters, namely BB6-DMT, BB5-DMT, BB6-DMI and BB5-DMI series, were prepared by melt polycondensation of dimethyl 4,4′-bibenzoate (BB) with a dimethyl phthalate (DMT: dimethyl terephthalate or DMI: dimethyl isophthalate) and an alkanediol (1,6-hexanediol or 1,5-pentanediol). The homopolyesters poly(hexamethylene 4,4′-bibenzoate) (BB6) and poly(pentamethylene 4,4′-bibenzoate) (BB5) exhibit a smectic phase. The thermotropic liquid crystalline and crystalline properties of the copolyesters are significantly influenced by the presence of the non-mesogenic rigid phthalate unit. All BB6-DMT copolyesters remain crystalline. As x, the molar fraction of the phthalate units in the diacid units, ≧ 0.7 the mesophase of the BB6-DMT copolyesters is destroyed completely. For BB5-DMT copolyesters, the mesophase disappears as x ≧ 0.4, and the copolyesters become amorphous as 0.5 ≦ x ≦ 0.8. The mesophase and the crystallinity of the BB6-DMI copolyesters are destroyed completely as x > 0.5. The BB5-DMI copolyesters lose the mesophase as x ≧ 0.3, and become amorphous as x ≧ 0.4. The results indicate that the non-linear isophthalate unit destroys mesophase and crystallinity of the copolyesters to a greater extent than the para-linked terephthalate unit.     

Epidemiologic relationship between fluoroquinolone-resistant Salmonella enterica Serovar Choleraesuis strains isolated from humans and pigs in Taiwan (1997 to 2002)

The emergence of ciprofloxacin-resistant Salmonella enterica serovar Choleraesuis in recent years has become an important public health issue in Taiwan. The resistant strains that cause human infections are considered to be from pigs. In this study, we characterized 157 swine and 42 human Salmonella serovar Choleraesuis isolates by pulsed-field gel electrophoresis (PFGE) and drug susceptibility testing to investigate the epidemiologic relationship among the isolates. By PFGE analyses, two major clusters (clusters GA and GB) were identified. Isolates in cluster GA were of both human and swine origins, while those in cluster GB were from pigs only. Among the various genotypes identified, genotype gt-1a was the most prevalent, which was found in 71% (30 of 42) and 48% (76 of 157) of human and swine isolates, respectively. The susceptibility tests for the 106 gt-1a isolates identified 44 susceptibility profiles and showed that 73% of human isolates and 34% of swine isolates were resistant to three fluoroquinolones (ciprofloxacin, enrofloxacin, and norfloxacin). Our findings indicate that a clonal group of Salmonella serovar Choleraesuis may have been circulating in human and swine populations in Taiwan for years and that the fluoroquinolone-resistant Salmonella serovar Choleraesuis strains most likely evolved from a gt-1a clone that emerged in 2000 and that then caused widespread infections in humans and pigs. Nevertheless, it is still debatable whether those Salmonella infections in humans are caused by isolates derived from pigs, on the basis of the higher fluoroquinolone and other antimicrobial resistance percentages in human isolates than in pig isolates.     

X-box binding protein 1 (XBP1) C--116G polymorphisms in bipolar disorders and age of onset

X-box binding protein 1 (XBP1), a critical gene in the endoplasmic reticulum stress response, is located on chromosome 22q12, which has been linked with bipolar disorders in several studies. Recently, associations have been reported between a polymorphism (-116C --> G) in the promoter region of XBP1, and bipolar disorders in both case-control study and family-based association study, however, this finding is not yet confirmed by other research using independent sample populations. To replicate this finding and determine the association between onset age of bipolar disorders and the XBP1 C--116G polymorphism, we investigated the prevalence of this polymorphism in a Chinese population (153 bipolar disorder patients and 174 controls). We were unable, however, to demonstrate a significant association between the C--116G polymorphism and bipolar disorders (P = 0.674 for genotype and P = 0.436 for allele frequency) or age at onset (P = 0.563). Further, no association was demonstrated between this polymorphism and family history in bipolar disorder patients. These negative findings suggest that the XBP1 C--116G polymorphism does not play a major role in the pathogenesis of bipolar disorders in Chinese populations.     

Comparison of serum specific IgE antibodies to staphylococcal enterotoxins between atopic children with and without atopic dermatitis

BACKGROUND: The skin of patients with atopic dermatitis (AD) exhibits a striking susceptibility to colonization and infection by Staphylococcus aureus. The exotoxins secreted by S. aureus can act as superantigens and classic allergens, inducing the production of functionally relevant specific IgE antibodies. The aim of this study was to compare the levels and positive rates of serum staphylococcal enterotoxin A (SEA)- and staphylococcal enterotoxin B (SEB)-specific IgE between atopic children with and without AD. METHODS: Sixty children with AD, 55 children with respiratory allergy without AD, and 24 nonatopic healthy children were studied. The levels and positive rates of serum SEA- and SEB-specific IgE were compared among three groups. The correlation between the levels or positive rates of serum SEA/SEB-specific IgE and the severity of AD or the presence of previous skin infections was studied. RESULTS: The children with AD had significantly higher levels and positive rates of serum SEA- and SEB-specific IgE than the atopic children without AD (P < 0.001) and the nonatopic children (P < 0.001). There was no significant difference in the levels and positive rates of serum SEA- and SEB-specific IgE between the atopic children without AD and the nonatopic children. With or without adjustment for the potential confounding effect of total serum IgE levels, the levels and positive rates of serum SEA- and SEB-specific IgE were significantly correlated with severity of AD (P <0.005), but they were not significantly different between AD children with and without previous skin infections. CONCLUSIONS: SEA and SEB may contribute to chronic inflammation and exacerbation of AD through the IgE-mediated immune response.     

Diagnosis and taxonomy of periodical psychosis

The concept and taxonomy of periodic psychosis still remains in controversy for the past 100 years. In China, it was first reported by Ji, and thereafter various rinds of terminology and views were given by different authors. In the presentation, clinical investigation and follow up were carried out in 62 cases. In many of these cases, the so-called "periodic psychosis" or "phasophrenia" was early clinical features of schizophrenia or manic-depression. In those cases with apparent symptoms and signs of diencephalic function, differential diagnosis should be carried out from organic brain syndrome. In a small number of cases, their clinical manifestations, conforming to previous diagnostic criteria, might be an uncommon syndrome. It was concluded by the authors that until now periodic could be considered only as a clinical syndrome rather than a disease entity.     

Association between Reduced Serum Zinc and Diastolic Dysfunction in Maintenance Hemodialysis Patients

Diastolic dysfunction is an emerging challenge among hemodialysis (HD) patients, and the associations between serum zinc with echocardiographic parameters and diastolic function remain uncertain. A total of 185 maintenance HD patients were stratified by the tertiles of serum zinc level to compare their clinical characteristics and echocardiography. Correlations of serum zinc levels with echocardiographic parameters were examined using Pearson’s analysis. Univariate and multivariate logistic regression analyses were performed to investigate the determinants of E/e’ ratio >15 and left atrial volume index (LAVI) > 34 mL/m², both indicators of diastolic dysfunction. Patients belonging to the first tertile of serum zinc level had a significantly higher E/e’ ratio and LAVI. Serum zinc levels were negatively correlated with E (r = −0.204, p = 0.005), E/e’ ratio (r = −0.217, p = 0.003), and LAVI (r = −0.197, p = 0.007). In a multivariate analysis, older age, diabetes, coronary artery disease, and lower serum zinc levels (OR = 0.974, 95% CI = 0.950–0.999, p = 0.039) were significantly associated with E/e’ ratio >15. Furthermore, diabetes and lower serum zinc levels (OR = 0.978, 95% CI = 0.958–0.999, p = 0.041) were significantly associated with LAVI >34 mL/m². Reduced serum zinc level was significantly associated with diastolic dysfunction among HD patients. Further prospective studies are warranted to investigate whether zinc supplementation can attenuate cardiac dysfunction in maintenance HD patients.     

In vivo imaging of neuroblastomas using GD2-targeting graphene quantum dots

BackgroundPatients with neuroblastoma, a common childhood malignancy, often have poor prognosis. It is mandatory to develop an accurate and efficient diagnostic tool for neuroblastomas, so that the treatment can be started early. Graphene quantum dot (GQD), a nanomaterial, can be used to carry proteins, genetic materials, or drugs. GD2, a disialoganglioside, is a surface antigen expressed on neuroblastoma. This study investigated the in vivo targeting and imaging of neuroblastomas using GD2-targeting GQDs.MethodsGQDs were synthesized and conjugated with anti-GD2 antibody (anti-GD2/GQDs). In vitro cytotoxicity of GQDs and anti-GD2/GQDs was studied in human neuroblastoma cells by 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide)-based colorimetric assay. The tumor tracking and imaging of anti-GD2/GQDs in mice were investigated by in vivo imaging system (IVIS).ResultsTreatment with GQDs or anti-GD2/GQDs induced no or mild cytotoxicity in fibroblasts and neuroblastoma cells. After co-incubation, GQDs and anti-GD2/GQDs were located in the cytoplasm and nucleus of neuroblastoma cells, with GQDs showing a blue fluorescence and anti-GD2/GQDs an orange/red emission. The IVIS images demonstrated accumulation of the fluorescence of anti-GD2/GQDs in the subcutaneous tumors in mice 24 h after intravenous injection of anti-GD2/GQDs.ConclusionsAnti-GD2/GQDs may potentially be used for the targeting and imaging of neuroblastomas in vivo.