Dentin regeneration based on tooth tissue engineering: A review

Missing or damaged teeth due to caries, genetic disorders, oral cancer, or infection may contribute to physical and mental impairment that reduces the quality of life. Despite major progress in dental tissue repair and those replacing missing teeth with prostheses, clinical treatments are not yet entirely satisfactory, as they do not regenerate tissues with natural teeth features. Therefore, much of the focus has centered on tissue engineering (TE) based on dental stem/progenitor cells to create bioengineered dental tissues. Many in vitro and in vivo studies have shown the use of cells in regenerating sections of a tooth or a whole tooth. Tooth tissue engineering (TTE), as a promising method for dental tissue regeneration, can form durable biological substitutes for soft and mineralized dental tissues. The cell-based TE approach, which directly seeds cells and bioactive components onto the biodegradable scaffolds, is currently the most potential method. Three essential components of this strategy are cells, scaffolds, and growth factors (GFs). This study investigates dentin regeneration after an injury such as caries using TE and stem/progenitor cell-based strategies. We begin by discussing about the biological structure of a dentin and dentinogenesis. The engineering of teeth requires knowledge of the processes that underlie the growth of an organ or tissue. Then, the three fundamental requirements for dentin regeneration, namely cell sources, GFs, and scaffolds are covered in the current study, which may ultimately lead to new insights in this field.     

Aqua mediated synthesis of substituted 2-amino-4H-chromenes catalyzed by green and reusable Preyssler heteropolyacid

A simple, clean and environmentally benign route to the synthesis of 2-amino-4H-chromenes is described using Preyssler type heteropolyacid, H(14)[NaP(5)W(30)O(110)], as a green and reusable catalyst in water. The products were obtained in very good yields.     

Effect of colchicine-induced polyploidy on morphological characteristics and essential oil composition of ajowan (<Emphasis Type="Italic">Trachyspermum ammi</Emphasis> L.)

Cyclophilins (CYPs) belong to the immunophilin superfamily, having the peptidyl prolyl cis/trans isomerase activity that can catalyze the cis/trans isomerisation process of proline residues. Previous studies have shown their importance in plants, but no comprehensive analysis of maize CYP family has been reported. In the present study, a whole-genome-wide analysis of maize CYP family was performed and 39 ZmCYP genes (ZmCYP1 to ZmCYP39) were identified from maize genome, which were unequally distributed on maize ten chromosomes. Phylogenetic analysis revealed a weak relationship among these ZmCYP genes. Furthermore, their gene structure and motif patterns also displayed variant within the gene family. Four segmental and one tandem duplicated gene pairs were found from 39 ZmCYP genes, respectively, indicating their roles in the expansion of maize CYP family. Expression analysis of 39 ZmCYP genes in maize tissues showed their differential tissue specific expression patterns. Quantitative real-time PCR analysis of 19 selected ZmCYP genes under salinity stress indicated their stress-inducible expression profile. Heterologous expression of ZmCYP15 in E. coli enhanced tolerance against abiotic stress. Subcellular localization analysis indicated ZmCYP15 was located in nucleus and cytoplasm. Our study describes the importance of the maize CYP gene family in stress response, and provides a reference for future study and application for maize genetic improvement.     

Coexistence of Sexual and Parthenogenetic Artemia Populations in Lake Urmia and Neighbouring Lagoons

We studied the Artemia populations existing in Lake Urmia (north‐western Iran), one of the largest habitats of Artemia in the world, in order to settle the long‐standing controversy over the sexual status of the endemic Artemia populations. Experiments were carried out in the laboratory and in the field. Cysts, collected from different sites of the lake and peripheral lagoons, were hatched and cultured to adults in the laboratory. Adult sexual and parthenogenetic animals were isolated and newly hatched nauplii from them were cultured to maturity in different salinities, ranging from 15–80 ppt. Survival levels and percentage of animals attaining adulthood were measured over a period of 30 days. In the field experiment, cysts taken from Lake Urmia were hatched and the resulting nauplii were inoculated into six earthen ponds (80–140 ppt) constructed in the vicinity of the lake. Population composition in each pond was determined over a period of two years. Results indicated that both sexual and parthenogenetic Artemia coexist in Lake Urmia. While the lake itself is dominated by sexual Artemia, the asexual populations were found to be restricted to particular areas in or near the lake. Artemia appearing seasonally in the lagoons adjacent to the lake were exclusively parthenogenetic. Parthenogens could grow, mature and reproduce at very low salinities (15–33 ppt), whereas higher salinities (above 50 ppt) were required for A. urmiana to attain sexual maturity. We consider salinity to be a major abiotic factor determining the distribution of these sexually different populations within and outside the lake. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Magnetic nanocomposite of anti-human IgG/COOH-multiwalled carbon nanotubes/Fe₃O₄ as a platform for electrochemical immunoassay

An electrochemical immunosensing method was developed based on a magnetic nanocomposite. The multiwalled carbon nanotubes (MWCNTs) were treated with nitric acid to produce carboxyl groups at the open ends. Then, Fe₃O₄ nanoparticles were deposited on COOH–MWCNTs by chemical coprecipitation of Fe²⁺ and Fe³⁺ salts in an alkaline solution. Goat anti-human IgG (anti-hIgG) was covalently attached to magnetic nanocomposite through amide bond formation between the carboxylic groups of MWCNTs and the amine groups of anti-hIgG. The prepared bio-nanocomposite was used for electrochemical sensing of human tetanus IgG (hIgG) as a model antigen. The anti-hIgG magnetic nanocomposite was fixed on the surface of a gold plate electrode using a permanent magnet. The hIgG was detected using horseradish peroxidase (HRP)-conjugated anti-hIgG in a sandwich model. Electrochemical detection of hIgG was carried out in the presence of H₂O₂ and KI as substrates of HRP. Using this method, hIgG was detected in a concentration range from 30 to 1000 ng ml^?1 with a correlation coefficient of 0.998 and a detection limit of 25 ng ml^?1 (signal/noise = 3). The designed immunosensor was stable for 1 month.     

Postoperative Staphylococcus aureus Infections in Medicare Beneficiaries

Staphylococcus aureus (S. aureus) infections are important because of their increasing frequency, resistance to antibiotics, and high associated rates of disabilities and deaths. We examined the incidence and correlates of S. aureus infections following 219,958 major surgical procedures in a 5% random sample of fee-for-service Medicare beneficiaries from 2004–2007. Of these surgical patients, 0.3% had S. aureus infections during the hospitalizations when index surgical procedures were performed; and 1.7% and 2.3%, respectively, were hospitalized with infections within 60 days or 180 days following admissions for index surgeries. S. aureus infections occurred within 180 days in 1.9% of patients following coronary artery bypass graft surgery, 2.3% following hip surgery, and 5.9% following gastric or esophageal surgery. Of patients first hospitalized with any major infection reported during the first 180 days after index surgery, 15% of infections were due to S. aureus, 18% to other documented organisms, and no specific organism was reported on claim forms in 67%. Patient-level predictors of S. aureus infections included transfer from skilled nursing facilities or chronic hospitals and comorbid conditions (e.g., diabetes, congestive heart failure, chronic obstructive pulmonary disease, and chronic renal disease). In a logarithmic regression, elective index admissions with S. aureus infection stayed 130% longer than comparable patients without that infection. Within 180 days of the index surgery, 23.9% of patients with S. aureus infection and 10.6% of patients without this infection had died. In a multivariate logistic regression of death within 180 days of admission for the index surgery with adjustment for demographics, co-morbidities, and other risks, S. aureus was associated with a 42% excess risk of death. Due to incomplete documentation of organisms in Medicare claims, these statistics may underestimate the magnitude of S. aureus infection. Nevertheless, this study generated a higher rate of S. aureus infections than previous studies.     

MicroRNA-203 reinforces stemness properties in melanoma and augments tumorigenesis in vivo

One of the challenges encountered in microRNA (miRNA) studies is to observe their dual role in different conditions and cells. This leads to a tougher prediction of their behavior as gene expression regulators. miR-203 has been identified to play a negative role in the progression of malignant melanoma; however, it has been reported, with dual effect, as both an oncomiR and tumor suppressor miRNA in some malignancies, such as breast cancer, meanwhile, the role of miR-203 in melanoma stem cells or even metastatic cells is unclear. In the present study, after observation of upregulation of miR-203 in melanoma patient's serum and also melanospheres as cancer stem cells model, we examined its overexpression on the stemness potential and migration ability of melanoma cells. Our data demonstrated that the increased miR-203 level was significantly associated with significant increase in the ability of proliferation, colony and spheres formation, migration, and tumorigenesis in A375 and NA8 cells. All of these changes were associated with enhancement of BRAF, several epithelial to mesenchymal transition factors, and stemness genes. In conclusion, our results clearly determined that miR-203 could be down-regulateddownregulated in melanoma tissues but be overexpressed in melanoma stem cells. It has an important role as oncomiR and promote repopulation, tumorigenicity, self-renewal, and migration. Therefore, we suggested overexpression of miR-203 as biomarker for early detection of metastasis. However, more studies are needed to validate our data.     

Semi-rational chemical modification of endoinulinase by pyridoxal 5′-phosphate and ascorbic acid

It is important to improve the quality of the enzyme inulinase used in industrial applications without allowing the treatment to have any adverse effects on enzyme activity. We achieved preferential chemical modification of the non-catalytic domain of endoinulinase (EC 3.2.1.7) to enhance the thermostability of the enzyme. We used pyridoxal 5′-phosphate (PLP) to modify the more accessible lysine residues at the surface of endoinulinase and then performed a necessary step of reduction with ascorbate. Endoinulinase was incubated in the presence of PLP at various concentrations; this step was followed by reduction of the resulting Schiff base and dialysis. The effects of different PLP concentrations and incubation times on enzyme modification were evaluated. Enzyme deactivation was observed immediately after treatment, even at low PLP concentrations, while reactivation was observed for samples treated with low PLP concentrations after a period of time. Structural analysis revealed that the α-helix content increased from 13.60% to 17.60% after applying the modification strategy; consequently, enzyme stabilization was achieved. The melting temperature (T_m) of the modified enzyme increased from 64.1 °C to 72.2 °C, and a comparative study of thermal stability at 25 °C, 45 °C, and 50 °C for 150 min confirmed that the enzyme was stabilized because of increase in its half-life (t_1/2) after PLP modification/ascorbate reduction. The modification process was optimized to achieve the optimum mole ratio for the PLP/endoinulinase (1.37). Excess moles of the modifier are thought to be responsible for enzyme deactivation through unwanted/nonspecific and noncovalent interactions, and the optimization ensured that there was no excess modifier after the desired covalent reaction was complete.     

Molecular Variation and Distribution of Anopheles fluviatilis (Diptera: Culicidae) Complex in Iran

Anopheles fluviatilis James (Diptera: Culicidae) is one of the known malaria vectors in south and southeastern Iran. Earlier ITS2 sequences analysis of specimens from Iran demonstrated only a single genotype that was identical to species Y in India, which is also the same as species T. We identified 2 haplotypes in the An. fluviatilis populations of Iran based on differences in nucleotide sequences of D3 domain of the 28S locus of ribosomal DNA (rDNA). Comparison of sequence data from 44 Iranian specimens with those publicly available in the Genbank database showed that all of the 28S-D3 sequences from Kazeroun and Khesht regions in Fars Province were identical to the database entry representing species U in India. In other regions, all the individuals showed heterozygosity at the single nucleotide position, which identifies species U and T. It is argued that the 2 species may co-occur in some regions and hybridize; however, the heterozygosity in the 28S-D3 locus was not reflected in ITS2 sequences and this locus for all individuals was identical to species T. This study shows that in a newly diverged species, like members of An. fluviatilis complex, a single molecular marker may not be sufficiently discriminatory to identify all the taxa over a vast geographical area. In addition, other molecular markers may provide more reliable information for species discrimination.