Silicone fouling-release coatings: effects of the molecular weight of poly(dimethylsiloxane) and tetraethyl orthosilicate on the magnitude of pseudobarnacle adhesion strength

A series of poly(dimethyl siloxane) (PDMS)/silica nanocomposites were synthesized utilizing a sol gel method. The samples were evaluated using pseudobarnacle adhesion and tensile strength tests. The effects of the molecular weight of the PDMS and the size and structure of the silica domains on biofouling release and the mechanical behavior of the PDMS/silica materials were investigated. Three different molecular weights (18,000, 49,000 and 79,000 g mol(-1)) of hydroxyl-terminated PDMS (HT-PDMS) were used to prepare the nanocomposites with three different weight ratios (1:1, 3:1 and 5:1) of HT-PDMS to tetraethyl orthosilicate (TEOS). TEOS served as a crosslinker to form PDMS networks and as a precursor to form silica domains. Two different variants of TEOS with regard to its degree of polymerization (n) (monomeric type: n ≈= 1 and oligomeric type: n ≈= 5) were used for in situ formation of silica particles via the sol-gel process. The mechanical properties of the composites were characterized using stress-strain isotherms. All the mechanical properties evaluated (Young's modulus, tensile strength, energy required for rupture, elongation at break) improved with increases in the molecular weight of the HT-PDMS and the silica content. The pseudobarnacle adhesion test was used to examine the fouling- release (FR) properties of coatings applied on aluminum plates. The rupture energy and tensile strength increased substantially when oligomeric TEOS was employed in the PDMS/silica composites. Scanning electron microscopy (SEM) was used to investigate the structure of the silica domains. It was found that the use of oligomeric TEOS in higher molecular weight PDMS samples with higher PDMS/TEOS weight ratios led to low pseudobarnacle adhesion strengths of ≈ 0.3 MPa, which is in the range of commercial FR coatings.     

Association of genetic polymorphisms of glutathione-S-transferase genes (GSTT1, GSTM1, and GSTP1) and susceptibility to nonalcoholic fatty liver disease in Zahedan, Southeast Iran

Oxidative damage is thought to play a pivotal role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Glutathione-S-transferases (GSTs) are involved in cell protection against oxidative stress. We examined whether GSTM1, GSTT1, and GSTP1 polymorphisms are associated with NAFLD in a sample of the Iranian population. The current case-control study included 83 patients with NAFLD and 93 healthy subjects. The GSTM1 and GSTT1 polymorphisms were analyzed by multiplex polymerase chain reaction (PCR). The GSTP1 polymorphism was detected by tetra amplification refractory mutation system-PCR assay. The GSTM1-null genotype was significantly associated with the development of NAFLD (odds ratios [OR]=2.171, 95% confidence intervals [CI]=1.188-3.970, p=0.015). The GSTP1 Val allele was shown to be a risk factor for NAFLD (OR=1.739, 95% CI=1.089-2.777, p=0.024). The GSTT1 polymorphism was not significantly different between control and patient groups (p=0.221). This study showed that GSTM1 and GSTP1, but not GSTT1, genetic polymorphisms are associated with NAFLD in a sample of the Iranian population, and may be used to determine the risk of development of NAFLD.     

Comparison of different methods for the isolation of mesenchymal stem cells from human umbilical cord Wharton’s jelly

Several techniques have been devised for the dissociation of tissues for primary culture. These techniques can affect the quantity and quality of the isolated cells. The aim of our study was to develop the most appropriate method for the isolation of human umbilical cord-derived mesenchymal (hUCM) cells. In the present study, we compared four methods for the isolation of hUCM cells: three enzymatic methods; collagenase/hyaluronidase/trypsin (CHT), collagenase/trypsin (CT) and trypsin (Trp), and an explant culture (Exp) method. The trypan blue dye exclusion test, the water-soluble tetrazolium salt-1 (WST-1) assay, flow cytometry, alkaline phosphatase activity and histochemical staining were used to evaluate the results of the different methods. The hUCM cells were successfully isolated by all methods but the isolation method used profoundly altered the cell number and proliferation capacity of the isolated cells. The cells were successfully differentiated into adipogenic and osteogenic lineages and alkaline phosphatase activity was detected in the hUCM cell colonies of all groups. Flow cytometry analysis revealed that CD44, CD73, CD90 and CD105 were expressed in all groups, while CD34 and CD45 were not expressed. The expression of C-kit in the enzymatic groups was higher than in the explant group, while the expression of Oct-4 was higher in the CT group compared to the other groups. We concluded that the collagenase/trypsin method of cell isolation yields a higher cell density than the others. These cells expressed a higher rate of pluripotent cell markers such as C-kit and Oct-4, while the explant method of cell isolation resulted in a higher cell proliferation rate and activity compared to the other methods.     

Ranitidine induces inhibition and structural changes in sucrase

Ranitidine is an antagonist of histamine-2 (H(2)) receptor. It is employed to treat peptic ulcer and other conditions in which gastric acidity must be reduced. Sucrase is a hydrolytic enzyme that catalyzes the breakdown of sucrose to its monomer content. A liquid of yeast sucrase was developed for treatment of congenital sucrase-isomaltase deficiency (CSID) in human. In this study, the effect of ranitidine on yeast sucrase activity was investigated. Our results showed that ranitidine binds to sucrase and inhibits the enzyme in a noncompetitive manner. The K(i) and IC(50) values were measured to be about 2.3 and 2.2 mM, respectively. Fluorescence measurement showed conformational changes after binding of ranitidine to the enzyme. The fluorescence spectra showed that ranitidine could bind to both free enzyme and enzyme-substrate complex, which was accompanied with reduction of emission intensity and red shift production.     

Toward genotype phenotype correlations in GFM1 mutations

Multiple respiratory chain deficiencies represent a common cause of mitochondrial diseases. We report two novel GFM1 mutations in two unrelated patients with encephalopathy and liver failure respectively. The first patient had intrauterine growth retardation, seizures, encephalopathy and developmental delay. Brain MRI showed hypoplasia of the vermis and severe pontine atrophy of the brainstem that were similar to those reported in patients with mitochondrial translation deficiencies. The second patient had liver failure with hypoglycemia. Respiratory chain analysis showed a complex IV deficiency in muscle of both patients. A 10K SNP genotyping detected several regions of homozygosity in the two patients. In vitro translation deficiency prompted us to study genes involved in mitochondrial translation. Therefore, we sequenced the GFM1 gene, encoding the mitochondrial translation factor EFG1, included in a shared homozygous region and identified two different homozygous mutations (R671C and L398P). Modeling studies of EFG1 protein suggested that the R671C mutation disrupts an inter-subunit interface and could locally destabilize the mutant protein. The second mutation (L398P) disrupted the H-bond network in a rich-beta-sheet domain, and may have a dramatic effect on local structure. GFM1 mutations have been seldom reported and are associated with different clinical presentation. By modeling the structure of the protein and the position of the various mutations we suggest that the clinical phenotypes of the patients could be related to the localization of the mutations.     

Serum level of specific IgG antibody for aspergillus and its association with severity of asthma in asthmatic children

Aspergillosis is one of the frequent causes of exacerbation of asthma depending on the geographical regions. The specific serum IgG level for aspergillus is a major diagnostic criterion in aspergillosis.Ninety-six asthmatic patients, with mean age of 5.4 ± 3.0 years who were referred to the asthma clinic of the Mofid Children's Hospital, were enrolled in this study. Serum specific IgG for aspergillus was measured and its association with severity of asthma was evaluated.Nineteen asthmatic patients (10 females and 9 males) had aspergillus IgG antibody. Among them, severe persistent asthma and moderate persistent asthma were detected in 5 and 13 cases, respectively, whereas only one patient suffered from mildpersistent asthma. A total of 36.5% of the 96 patients had a history of atopy, while 26% had allergic rhinitis. There was an association between the severity of asthma and the presence of aspergillus IgG antibody. Moreover, the positivity for aspergillus IgG antibody was higher in older patients.Our results indicated an association between aspergillus antibody level and severity of asthma. It could be recommended that the IgG titer for aspergillus is measured in pediatric patients with asthma, whereas co-morbidity of aspergillosis and asthma increases the risk of asthma exacerbation.     

The endothelin axis in uterine leiomyomas: new insights

The endothelin axis, comprising endothelin-1 (ET-1) and its receptors (ETA and ETB), is involved in the pathophysiology of different human tumors. Here we review conventional approaches and gene expression profiling indicating the association of ET-1 and its cognate receptors with human and rat leiomyomas, the most common benign tumors of myometrium. Specifically, ET-1/ETA interactions affect human and rat leiomyoma cell proliferation through protein kinase C and mitogen-activated protein kinase-dependent signaling pathways. Recent experiments demonstrate that the ET-1 axis exerts a potent antiapoptotic effect involving sphingolipid metabolism and prostaglandin-endoperoxide synthase 2/prostaglandin system in the rat Eker leiomyoma tumor-derived ELT3 cell line. Evidence supports that steroid hormones, growth factors, and extracellular matrix are key regulators of the leiomyoma growth. Interestingly, the ET-1 axis is under steroid hormones and can cooperate with these growth factors. Therefore, ET-1 alone or in association with these factors could contribute to the complex regulation of uterine tumor growth, such as proliferation, survival, and extracellular matrix production. This review summarizes current knowledge and emerging data on ET-1 in uterine leiomyoma pathology.     

Comparison of different methods for erythroid differentiation in the K562 cell line

Objective

To compare methods for erythroid differentiation of K562 cells that will be promising in the treatment of beta-thalassemia by inducing γ-globin synthesis.

Results

Cells were treated separately with: RPMI 1640 medium without glutamine, RPMI 1640 medium without glutamine supplemented with 1 mM sodium butyrate, RPMI 1640 medium supplemented with 1 mM sodium butyrate, 25 µg cisplatin/ml, 0.1 µg cytosine arabinoside/ml. The highest differentiation (84 %) with minimum toxicity was obtained with cisplatin at 15 µg /ml. Real-time RT-PCR showed that expression of the γ-globin gene was significantly higher in the cells differentiated with cisplatin compared to undifferentiated cells (P < 0.001).

Conclusions

Cisplatin is useful in the experimental therapy of ß-globin gene defects and can be considered for examining the basic mechanism of γ-reactivation.

     

A dual functional turn off florescence sensor using metal–organic framework for sensitive detection of aluminum(III) in aqueous solution

Aluminum, classified as one of the toxic heavy metals, has a recommended daily consumption limit of 3–10 mg, as specified by the World Health Organization (WHO). Herein, the selective and sensitive aluminum(III) fluorescence sensor based on TMU-16 metal–organic frameworks (MOFs) in aqueous medium, is reported. A sensing pathway was found via the cation exchange between aluminum(III) and zinc(II) ions, and caused selectivity and sensitivity detection of aluminum(III) with a 5–100 ppm linear range and 1.99 ppm limit of detection (LOD). This sensor offers the advantage of accurately determining the concentration range of aluminum(III) ions. At low concentrations, only fluorescence quenching was observed, while at higher concentrations, fluorescence emission not only undergoes quenching but also exhibits a blue shift in wavelength. Notably, the sensor demonstrates no interference from cation solutions of mercury(II), zinc(II), nickel(II), lead(II), cobalt(II), cadmium(II), silver(I), chromium(III), and iron(III). Another significant feature of this sensor is its selectivity toward copper(II) and aluminum(III) ions, due to quenching fluorescence in the presence of copper(II) ion. The results presented the sensor's selectivity toward copper(II) at low concentrations and aluminum(III) at high concentrations.