Improvement of tissue survival of skin flaps by 5 alpha-reductase inhibitors: possible involvement of nitric oxide and inducible nitric oxide synthase

Skin flap grafting is a popular approach for reconstruction of critical skin and underlying soft tissue injuries. In a previous study, we demonstrated the beneficial effects of two 5alpha-reductase inhibitors, azelaic acid and finasteride, on tissue survival in a rat model of skin flap grafting. In the current study, we investigated the involvement of nitric oxide and inducible nitric oxide synthase [iNOS] in graft survival mediated by these agents. A number of 42 male rats were randomly allocated into six groups: 1, normal saline topical application; 2, azelaic acid [100 mg/flap]; 3, finasteride [1 mg/flap]; 4, injection of L-N[G]-nitroarginine methyl ester [L-NAME] [i.p., 20 mg/kg]; 5, L-NAME [20 mg/kg, i.p.] + azelaic acid [100 mg/flap, topical]; 6, L-NAME [20 mg/kg, i.p.] + finasteride [1 mg/flap, topical]. Tissue survival, level of nitric oxide, and iNOS expression in groups were measured. Our data revealed that azelaic acid and finasteride significantly increased the expression of iNOS protein and nitric oxide [NO] levels in graft tissue [P < 0.05]. These increases in iNOS expression and NO level were associated with higher survival of the graft tissue. It appears that alterations of the NO metabolism are implicated in the azelaic acid- and finasteride-mediated survival of the skin flaps

Cloning, expression, purification and immunoreactivity analysis of gag derived protein p17 from HIV-1 CRF35 in fusion with thioredoxin from human subjects

So far, recombinant antigens of HIV-1, the etiologic cause of Acquired Immunodeficiency Syndrome [AIDS], have been widely used for the diagnosis and vaccine development. P17 or the matrix protein formed by the proteolytic cleavage of gag is strongly antigenic and is as conserved and immunogenic as p24. In some cases, antibodies to p17 are more prevalent than antibodies to p24 and the decline in the level of p17 antibodies is an earlier prognostic marker for disease progression than decline in the level of antibodies to p24. The aim of this study was to clone and express the gag derived p17 protein in soluble form in E. coli and then assess the immunoreactivity of produced recombinant p17. DNA sequence encoding p17 matrix protein was cloned from PTZ-gag53-IR vector that has the complete gag polyprotein sequence. The T7-promoter-based expression system used in this study was TOPO directional cloning strategy that expressed p17 matrix protein in fusion with thioredoxin in E. Coli. Purification of produced recombinant protein has been done using Ni-NTA nickel chelating agarose beads. Sequencing result of the cloned sequence showed that it belongs to CRF35_AD subtype of HIV-1 which is highly prevalent in Iran and Afghanistan. The immunoreactivity of produced recombinant p17 to sera from infected individuals showed 93.8% sensitivity and 100% specificity

Biocompatibility study of a hydroxyapatite-aiumina and silicon carbide composite scaffold for bone tissue engineering

To date, several scaffolds have been fabricated for application in bone tissue repair. However, there remains a need for synthesis of scaffolds with better mechanical properties, which can be applied to defects in weight-bearing bones. We constructed a composite ceramic bioscaffold of hydroxyapatite-alumina and silicon carbide [HA-Al2O3- SiC] to take advantage of the mechanical properties of this combination and show that it supports osteoblast-like cell attachment and growth. Ceramic composite microporous scaffolds were synthesized using an organic template [commercial polyurethane sponge with an open, interconnected microporosity]. Osteoblast-like cells [Saos-2] were then cultured on the scaffold and their growth pattern and viability were compared with those cultured in cell culture-treated flasks. Scanning electron microscopy [SEM] was used to assess cell attachment and migration. The fabricated scaffold shows fairly uniform pore morphologies. Cell growth and viability studies show that the scaffold is able to support osteoblast attachment and growth. However, SEM images indicated that the cells do not spread optimally on the scaffold surfaces. Our data suggest that that a ceramic hydroxyapatite-alumina and silicon carbide composite scaffold is a viable option for bone tissue repair. However, its surface properties should be optimized to maximise the attachment of osteoblasts