Cytotoxic effects of Mn(III) N-alkylpyridylporphyrins in the presence of cellular reductant, ascorbate

Due to the ability to easily accept and donate electrons Mn(III)N-alkylpyridylporphyrins (MnPs) can dismute O(2)(·-), reduce peroxynitrite, but also generate reactive species and behave as pro-oxidants if conditions favour such action. Herein two ortho isomers, MnTE-2-PyP(5+), MnTnHex-2-PyP(5+), and a meta isomer MnTnHex-3-PyP(5+), which differ greatly with regard to their metal-centered reduction potential, E(1/2) (Mn(III)P/Mn(II)P) and lipophilicity, were explored. Employing Mn(III)P/Mn(II)P redox system for coupling with ascorbate, these MnPs catalyze ascorbate oxidation and thus peroxide production. Consequently, cancer oxidative burden may be enhanced, which in turn would suppress its growth. Cytotoxic effects on Caco-2, Hela, 4T1, HCT116 and SUM149 were studied. When combined with ascorbate, MnPs killed cancer cells via peroxide produced outside of the cell. MnTE-2-PyP(5+) was the most efficacious catalyst for peroxide production, while MnTnHex-3-PyP(5+) is most prone to oxidative degradation with H(2) , and thus the least efficacious. A 4T1 breast cancer mouse study of limited scope and success was conducted. The tumour oxidative stress was enhanced and its microvessel density reduced when mice were treated either with ascorbate or MnP/ascorbate; the trend towards tumour growth suppression was detected.     

Association of common variants of vascular endothelial growth factor and interleukin-18 genes with allograft survival in renal transplant recipients of North India

Increased vascular endothelial growth factor (VEGF) production promotes enhanced endothelial permeability, enhanced leukocyte migration into the allograft, thereby leading to a clinically recognized rejection episode. Interleukin-18 (IL-18), a potent proinflammatory cytokine, may also be involved in mechanisms of kidney allograft rejection. The present study was, therefore, undertaken to investigate the association of functional polymorphisms in VEGF (2578C>A, 1154A>G) and IL-18 (607C>A, 137G>C) genes with risk of allograft rejection in renal transplant recipients of North India. Two hundred renal transplant recipients, 150 matched recipients-donors, and 200 unrelated healthy individuals were genotyped by amplification refractory mutation specific polymerase chain reaction and by polymerase chain reaction-restriction fragment length polymorphism. Variant allele VEGF 1154A>G (p?=?0.56; odds ratio [OR]?=?1.32) and variant allele (p?=?0.004, OR?=?1.54) and variant genotype (p?=?0.007, OR?=?3.26) of IL-18 607C>A, GC of IL-18 137G>C (p?=?0.043, OR?=?0.63) were significantly different in healthy individuals as compared with the patients with renal transplant. When 114 nonrejectors were compared with 36 rejectors (150 recipients) for association with allograft rejection, significant association was observed in heterozygous genotype of VEGF 2578C>A (p?=?0.033), VEGF 1154A>G (p?=?0.024). In IL-18 137G>C, CC genotype, C allele showed protective association with allograft rejection. Kaplan-Meier analysis indicated a higher mean time for first rejection episode in CA genotype carriers (31 months) as compared with AA (29 months) for VEGF 2578C>A (log p?=?0.035). In VEGF, the haplotypes A-A and A-G (2578-1154) were associated with reduced risk and in IL-18 607A-137G, they were associated with high risk for allograft rejection. This observation suggests these polymorphisms are an ideal marker for prediction of pretransplant allograft outcome.     

Thermal Unfolding Curves of High Concentration Bovine IgG Measured by FTIR Spectroscopy

The purpose of this research is to study the thermal unfolding of high concentration bovine Immunoglobulin G (IgG) under 26 different experimental conditions by Fourier Transform Infrared spectroscopy with improved purge conditions and software calculations. When bovine IgG (25–200 mg/mL) was thermally denatured between pH 4.0 and 8.0, it was observed that at 25 mg/mL concentration, the protein exhibited maximum thermal stability at pH 6.0 and 7.0 as evident from the apparent T_m values. Increasing the concentration from 25 to 100 mg/mL at those pH values increased the thermal resistance of the protein by 2–3 °C. But, at 200 mg/mL, IgG showed a small decrease in its transition temperature. Presence of 100 mM Trehalose enhanced the T_m values at all conditions and possibly prevented the complete loss of IgG as insoluble aggregates at higher temperatures. Second derivative plots were constructed to explain the conformational changes of IgG during thermal unfolding.     

Chemical constituents and antimicrobial activity of the leaf and rhizome oils of Alpinia pahangensis Ridl., an endemic wild ginger from peninsular Malaysia

The essential oils from the leaves and rhizomes of Alpinia pahangensis Ridl ., collected from Pahang, Peninsular Malaysia, were obtained by hydrodistillation, and their chemical compositions were determined by GC and GC/MS analyses. The major components of the rhizome oil were γ‐selinene (11.60%), β‐pinene (10.87%), (E,E)‐farnesyl acetate (8.65%), and α‐terpineol (6.38%), while those of the leaf oil were β‐pinene (39.61%), α‐pinene (7.55%), and limonene (4.89%). The investigation of the antimicrobial activity of the essential oils using the broth microdilution technique revealed that the rhizome oil of A. pahangensis inhibited five Staphylococcus aureus strains with minimum inhibitory concentration (MIC) values between 0.08 and 0.31 μg/μl, and four selected fungi with MIC values between 1.25 and 2.50 μg/μl.     

Thermal Stability of Rhodopsin and Progression of Retinitis Pigmentosa: COMPARISON OF S186W AND D190N RHODOPSIN MUTANTS

Over 100 point mutations in the rhodopsin gene have been associated with retinitis pigmentosa (RP), a family of inherited visual disorders. Among these, we focused on characterizing the S186W mutation. We compared the thermal properties of the S186W mutant with another RP-causing mutant, D190N, and with WT rhodopsin. To assess thermal stability, we measured the rate of two thermal reactions contributing to the thermal decay of rhodopsin as follows: thermal isomerization of 11-cis-retinal and hydrolysis of the protonated Schiff base linkage between the 11-cis-retinal chromophore and opsin protein. We used UV-visible spectroscopy and HPLC to examine the kinetics of these reactions at 37 and 55 °C for WT and mutant rhodopsin purified from HEK293 cells. Compared with WT rhodopsin and the D190N mutant, the S186W mutation dramatically increases the rates of both thermal isomerization and dark state hydrolysis of the Schiff base by 1–2 orders of magnitude. The results suggest that the S186W mutant thermally destabilizes rhodopsin by disrupting a hydrogen bond network at the receptor''s active site. The decrease in the thermal stability of dark state rhodopsin is likely to be associated with higher levels of dark noise that undermine the sensitivity of rhodopsin, potentially accounting for night blindness in the early stages of RP. Further studies of the thermal stability of additional pathogenic rhodopsin mutations in conjunction with clinical studies are expected to provide insight into the molecular mechanism of RP and test the correlation between rhodopsin''s thermal stability and RP progression in patients.     

Rationally Designed Transmembrane Peptide Mimics of the Multidrug Transporter Protein Cdr1 Act as Antagonists to Selectively Block Drug Efflux and Chemosensitize Azole-resistant Clinical Isolates of Candida albicans

Drug-resistant pathogenic fungi use several families of membrane-embedded transporters to efflux antifungal drugs from the cells. The efflux pump Cdr1 (Candida drug resistance 1) belongs to the ATP-binding cassette (ABC) superfamily of transporters. Cdr1 is one of the most predominant mechanisms of multidrug resistance in azole-resistant (AR) clinical isolates of Candida albicans. Blocking drug efflux represents an attractive approach to combat the multidrug resistance of this opportunistic human pathogen. In this study, we rationally designed and synthesized transmembrane peptide mimics (TMPMs) of Cdr1 protein (Cdr1p) that correspond to each of the 12 transmembrane helices (TMHs) of the two transmembrane domains of the protein to target the primary structure of the Cdr1p. Several FITC-tagged TMPMs specifically bound to Cdr1p and blocked the efflux of entrapped fluorescent dyes from the AR (Gu5) isolate. These TMPMs did not affect the efflux of entrapped fluorescent dye from cells expressing the Cdr1p homologue Cdr2p or from cells expressing a non-ABC transporter Mdr1p. Notably, the time correlation of single photon counting fluorescence measurements confirmed the specific interaction of FITC-tagged TMPMs with their respective TMH. By using mutant variants of Cdr1p, we show that these TMPM antagonists contain the structural information necessary to target their respective TMHs of Cdr1p and specific binding sites that mediate the interactions between the mimics and its respective helix. Additionally, TMPMs that were devoid of any demonstrable hemolytic, cytotoxic, and antifungal activities chemosensitize AR clinical isolates and demonstrate synergy with drugs that further improved the therapeutic potential of fluconazole in vivo.     

Fabrication and characterization of biomaterial film from gland silk of muga and eri silkworms

This study discusses the possibilities of liquid silk (Silk gland silk) of Muga and Eri silk, the indigenous non mulberry silkworms of North Eastern region of India, as potential biomaterials. Silk protein fibroin of Bombyx mori, commonly known as mulberry silkworm, has been extensively studied as a versatile biomaterial. As properties of different silk‐based biomaterials vary significantly, it is important to characterize the non mulberry silkworms also in this aspect. Fibroin was extracted from the posterior silk gland of full grown fifth instars larvae, and 2D film was fabricated using standard methods. The films were characterized using SEM, Dynamic contact angle test, FTIR, XRD, DSC, and TGA and compared with respective silk fibers. SEM images of films reveal presence of some globules and filamentous structure. Films of both the silkworms were found to be amorphous with random coil conformation, hydrophobic in nature, and resistant to organic solvents. Non mulberry silk films had higher thermal resistance than mulberry silk. Fibers were thermally more stable than the films. This study provides insight into the new arena of research in application of liquid silk of non mulberry silkworms as biomaterials. © 2012 Wiley Periodicals, Inc. Biopolymers 99: 292–333, 2013.     

Factors shaping the evolution of colour patterns in Australian agamid lizards (Agamidae): a comparative study

Identifying general patterns of adaptive coloration in animals can help to elucidate the evolutionary processes that generate them. We examined the evolution of colour patterns in Australian agamid lizards, a morphologically and ecologically diverse group that relies primarily on visual communication. We tested whether certain types of colour (yellow–reds and black) were likely to be used as sexual signals, as indicated by their association with indices of sexual selection, namely, sexual dichromatism and sexual dimorphism in body size and head shape. We then tested whether sexually dichromatic colours are associated with specific patterns (uniform, mottled, striped, blotched, reticulated) or ecological variables such as habitat openness, arboreality, and substrate type. The presence of yellow–red on lateral and ventral body regions and black on ventral body regions was significantly more common in males than females. Lateral yellow–red in males was associated with the total extent of sexual dichromatism and size dimorphism, whereas ventral yellow–red was associated with sexual dichromatism. Both lateral and ventral yellow–red were associated with uniform patterning, suggesting that sexual signals in male agamid lizards may often comprise uniform patches or flushes of yellow–red. Although ventral black coloration was more prevalent on males (i.e. strongly sexually dichromatic), it was not associated with indices of sexual selection, suggesting that, in agamid lizards, yellow–red coloration is more likely to be sexually selected than black. Sexually dichromatic coloration was not strongly associated with any of the ecological variables measured. We found some associations, however, between female dorsal patterns and ecological variables, suggesting that female patterns are influenced by natural selection. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 101–112.