High pressure torsion induced lowering of Young's modulus in high strength TNZT alloy for bio-implant applications

An exceptional combination of low Young's modulus (E ~68 GPa) and high flow strength (σ_f ~1 GPa) was achieved for a consolidated β-Ti-based metastable Ti-35Nb-7Zr-5Ta (TNZT) alloy subjected to room temperature high-pressure torsion (HPT). The mechanical properties of the alloy were studied by quasistatic nanoindentation tests at different strain rates, where a reduction in Young's modulus E ~73 GPa (N_HPT¹⁰) and E ~68 GPa (N_HPT⁴⁰) is observed together with an increase in plastic deformability (or HPT rotations). The microstructure evolution with increasing shear strain has been investigated. The stabilized bcc β-Ti phase with homogeneous nanostructure distribution was observed leading to a low Young's modulus. Severe straining causes a uniform hardness distribution without any noticeable change in the strength of the material. This study may be useful for developing excellent removable implant materials.

Deformation mechanisms to ameliorate the mechanical properties of novel TRIP/TWIP Co-Cr-Mo-(Cu) ultrafine eutectic alloys

In the present study, the microstructural evolution and the modulation of the mechanical properties have been investigated for a Co-Cr-Mo (CCM) ternary eutectic alloy by addition of a small amount of copper (0.5 and 1 at.%). The microstructural observations reveal a distinct dissimilarity in the eutectic structure such as a broken lamellar structure and a well-aligned lamellar structure and an increasing volume fraction of Co lamellae as increasing amount of copper addition. This microstructural evolution leads to improved plasticity from 1% to 10% without the typical tradeoff between the overall strength and compressive plasticity. Moreover, investigation of the fractured samples indicates that the CCMCu alloy exhibits higher plastic deformability and combinatorial mechanisms for improved plastic behavior. The improved plasticity of CCMCu alloys originates from several deformation mechanisms; i) slip, ii) deformation twinning, iii) strain-induced transformation and iv) shear banding. These results reveal that the mechanical properties of eutectic alloys in the Co-Cr-Mo system can be ameliorated by micro-alloying such as Cu addition.

A study on evalution of antidepressant effect of imipramine adjunct with Aswagandha and Bramhi

Depressive disorders increase the risks of self-harm or even suicide in patients. Indigenous drugs are being tried to treat such patient along with conventional antidepressant drugs. This study was planned to investigate the antidepressant action of Ashwagandha and Bramhi and also to confirm its efficacy in the behavioural despair animal model of depression. Normal saline as control (5 ml/kg), Imipramine as standard (16, 32, 64 mg/ kg) and Ashwagandha (50, 100, 150 mg/kg), Bramhi (20, 40, 80 mg/kg) as test drugs were introduced to the albino rats weighing between 200-250 gm for 2 weeks, 1 hr before electric shock in Learned helplessness test (LHT) and swimming in Forced swimming test (FST). Effects of individual drugs as well as their combination were evaluated. Avoidance response, escape failure and immobility period in case of Imipramine and Ashwagandha showed highly significant (p < 0.01) result on individual use. There was no significant result in case of Bramhi used alone except in escape failure and immobility period (FST), where at higher doses it showed significant (p < 0.01) result. But combination of Bramhi and Ashwagandha in low doses with low dose of Imipramine gave a highly significant result (p < 0.01) in all the parameters. Ashwagandha had significant antidepressant action, but Bramhi had not when used alone. Combination of these two indigenous drug with Imipramine showed high efficacy in animal model.

Activation of the human PAX6 gene through the exon 1 enhancer by transcription factors SEF and Sp1

PAX6 is a transcription factor that plays a major role in ocular morphogenesis. PAX6 is expressed in the eye, central nervous system and pancreas. Two alternative promoters, P0 and P1, which are differentially regulated during development, drive PAX6 transcription. We identified a 57 bp cis-regulatory element in exon 1 of the human PAX6 gene exon 1 enhancer (EIE). EIE enhances P1-driven PAX6 expression. Three regions in E1E (E1E-1, E1E-2 and E1E-3) have sequence similarities with binding sites of transcription factors ARP-1, Isl-1 and SEF, respectively. As shown by electrophoretic mobility shift assays, E1E-3, but not E1E-1 or E1E-2, bound to proteins in nuclear extracts of human glioma cells and transcription factor SEF bound to E1E-3. As shown by transient transfection experiments, deletion or site-specific mutations in E1E-3 dramatically decreased P1 promoter activity. Mutations in E1E-2, however, did not affect function of the P1 promoter. Co-transfection of SEF and PAX6 promoter-reporter constructs showed that SEF up-regulates PAX6 gene expression through the P1 promoter. Two Sp1 sites in the E1E region were also shown to be important by transient co-transfection assays. Data from immunoprecipitation and transient transfection assays demonstrated that SEF and Sp1 interacted in vitro and may act together in vivo to regulate PAX6 expression.

Inheritance of unequal numbers of the genes encoding the human neutrophil defensins HP-1 and HP-3

It is unclear whether the six known human defensin peptides are all encoded by separate genes or whether some of them are allelic. Three of the peptides, HP-1, HP-2, and HP-3, differ by only one amino acid, and it is thought that HP-2 may represent a proteolytic product of HP-1 and/or HP-3. To help determine the relationship of these three proteins, we isolated a nearly full-length cDNA encoding HP-1 with a sequence very similar to, but different from, the previously isolated HP-1 and -3 cDNAs. Gene copy number experiments established that there were at least two but fewer than five defensin genes with a high level of similarity to the HP-1 cDNA (HP-1/3-like). Three genomic clones were isolated that contained two different configurations of the HP-1/3-like sequences. Sequencing established that one encoded the HP-1 peptide, whereas the other encoded HP-3. Analysis of DNAs obtained from 18 unrelated individuals by Southern blot analysis revealed the expected fragments as well as additional fragments that were not present in the genomic clones. This suggested the possibility of alleles; however, when DNAs from families were examined, these fragments did not segregate in an obvious Mendelian fashion. The HP-1/3-like defensin genes are on human chromosome 8. Surprisingly, somatic cell hybrid mapping showed that the number of HP-1/3-like genes on isolated copies of chromosome 8 was variable. We conclude that individuals can inherit versions of chromosome 8 harboring either two or three copies of the genes that encode the HP-1, HP-2, and/or HP-3 peptides.

Transcriptional regulation of the human Wilms' tumor gene (WT1). Cell type-specific enhancer and promiscuous promoter

The Wilms' tumor gene, WT1, is expressed in few tissues, mainly the developing kidney, genitourinary system, and mesothelium, and in immature hematopoietic cells. To develop an understanding of the role of WT1 in development and tumorigenesis, we have identified transcriptional regulatory elements that function in transient reporter gene constructs transfected into kidney and hematopoietic cell lines. We found three transcription start sites of the WT1 gene and have identified an essential promoter region by deletion analysis. The WT1 promoter is a member of the GC-rich, TATA-less, and CCAAT-less class of polymerase II promoters. Whereas the WT1 promoter is similar to other tumor suppressor gene promoters, the WT1 expression pattern (unlike Rb and p53) is tissue-restricted. The WT1 GC-rich promoter is promiscuous, functioning in all cell lines tested, independent of WT1 expression. This finding suggests that the promoter is not tissue-specific, but that tissue-specific expression of WT1 is modulated by additional regulatory elements. Indeed, we have identified a transcriptional enhancer located 3' of the WT1 gene > 50 kilobases downstream from the promoter. This orientation-independent enhancer increases the basal transcription rate of the WT1 promoter in the human erythroleukemia cell line K562, but not in any of the other cell lines tested.

Ubiquitous expression of the 43- and 44-kDa forms of transcription factor USF in mammalian cells

USF is a helix-loop-helix transcription factor that, like Myc, recognizes the DNA binding motif CACGTG. Two different forms of USF, characterized by apparent molecular weights of 43,000 and 44,000, were originally identified in HeLa cells by biochemical analysis. Clones for the 43-kDa USF were first characterized, but only partial clones for the human 44-kDa USF (USF2, or FIP) have been reported. Here we describe a complete cDNA for the 44-kDa USF from murine cells. Analysis of this clone has revealed that the various USF family members are quite divergent in their N-terminal amino acid sequences, while a high degree of conservation characterizes their dimerization and DNA-binding domains. Interestingly, the 3' noncoding region of the 44-kDa USF cDNAs displayed an unusual degree of conservation between human and mouse. In vitro transcription/translation experiments indicated a possible role for this region in translation regulation. Alternative splicing forms of the 44-kDa USF messages exist in both mouse and human. Examination of the tissue and cell-type distribution of USF by Northern blot and gel retardation assays revealed that while expression of both the 43- and 44-kDa USF species is ubiquitous, different ratios of USF homo- and heterodimers are found in different cells.

Studies on the antineoplasticity of Schiff bases containing 5-nitrofuran and pyrimidine

Antineoplastic properties of different Schiff bases obtained by the interaction of 5-nitrofuran with substituted pyrimidines have been examined both in vitro and in vivo. In vitro studies on L 5178Y/asparaginase sensitive, HL 60 and P 388 cell lines and in vivo studies on the P 388 cell line indicate that all the compounds are potential antineoplastic agents. However, 2-(5-nitro-2-furfurylidene-amino)-pyrimidine (SBP1) is the most effective, and 2-(5-nitro-2-furfurylidene-amino)-6-hydroxypyrimidine (SBP3) is the least effective agent. Doubling time, rates of protein and DNA synthesis inhibition and LD50 values-1,000 mg/kg body weight for SBP1 and 1,275 mg/kg body weight for 2-(5-nitro-2-furfurylidene-amino)-4- methylpyrimidine (SBP2)- in the oral route support the activity and use of SBP1 and SBP2 as future anticancer agents.