Role played by BRCA1 in regulating the cellular response to stress

BRCA1 (breast-cancer susceptibility gene 1) is a tumour suppressor gene that is mutated in the germline of women with a genetic predisposition to breast and ovarian cancer. In this review, we examine the role played by BRCA1 in mediating the cellular response to stress. We review the role played by BRCA1 in detecting and signalling the presence of DNA damage, particularly double-strand DNA breaks, and look at the evidence to support a role for BRCA1 in regulating stress response pathways such as the c-Jun N-terminal kinase/stress-activated protein kinase pathway. in addition, we examine the role played by BRCA1 in mediating both cell-cycle arrest and apoptosis following different types of cellular insult, and how this may be modulated by the presence or absence of associated proteins such as p53. Finally, we explore the possibility that many of the functions associated with BRCA1 may be based on transcriptional regulation of key downstream genes that have been implicated in the regulation of these specific cellular pathways.

Rheological characterization of thermoresponsive semisolids for vaginal HIV vaccine delivery

Purpose. To manufacture and characterize, through oscillatory rheology, thermoresponsive rheologically structured vehicles
(RSV’s) capable of enhanced retention times within the vagina for the purposes of HIV vaccine delivery.
Methods. Pluronics F127, F108 and F68 were investigated and RSV’s were prepared by dissolving sorbic acid (0.1% w/w)
and mucoadhesive component (Gantrez SBF97 or Noveon AA1, 3% w/w) in the required amount of H2O and NaOH.
Pluronic (10% w/w) was added via mixing in an ice-bath followed by hydroxyethylcellulose (5%) and subsequently
poly(vinylpyrollidone) (4%w/w). Oscillatory temperature sweeps between 10-38°C were preformed within the linear
viscoelastic region of the formulations on an AR2000 rheometer (T.A. Instruments, Surrey, England) with a 2cm diameter
parallel plate geometry and a plate gap of 1000µm at 1Hz.

Characterization of the Rheological, Mucoadhesive, and Drug Release Properties of Highly Structured Gel Platforms for Intravaginal Drug Delivery

This investigation describes the formulation and characterization of theologically structured vehicles (RSVs) designed for improved drug delivery to the vagina. Interactive, multicomponent, polymeric platforms were manufactured containing hydroxyethylcellulose (HEC, 5% w/w) polyvinylpyrrolidone (PVP, 4% w/w), Pluronic (PL, 0 or 10% w/w), and either polycarbophil (PC, 3% w/w) or poly(methylvinylether-co-maleic anhydride) (Gantrez S97, 3% w/w) as a mucoadhesive agent. The rheological (torsional and dynamic), mechanical (compressional), and mucoadhesive properties were characterized and shown to be dependent upon the mucoadhesive agent used and the inclusion/exclusion of PL. The dynamic theological properties of the gel platforms were also assessed following dilution with simulated vaginal fluid (to mimic in vivo dilution). RSVs containing PC were more rheologically structured than comparator formulations containing GAN. This trend was also reflected in formulation hardness, compressibility, consistency, and syringeability. Moreover, formulations containing PL (10% w/w) were more theologically structured than formulations devoid of PL. Dilution with simulated vaginal fluids significantly decreased rheological structure, although RSVs still retained a highly elastic stnicture (G' > G '' and tan delta <1). Furthermore, RSVs exhibited sustained drug release properties that were shown to be dependent upon their rheological structure. It is considered that these semisolid drug delivery systems may be useful as site-retentive platforms for the sustained delivery of therapeutic agents to the vagina.

Reduction of Staphylococcus aureus and Pseudomonas aeruginosa colonisation on PVC through covalent surface attachment of fluorinated thiols

OBJECTIVES: This study reports the development, characterisation and microbiological testing of surface-modified polyvinylchloride (PVC) films for the purpose of reducing bacterial adherence.

METHODS: Irreversible covalent surface modification was achieved via nucleophilic substitution of fluorinated thiol-terminated compounds onto the polymer backbone. Four fluorinated modifiers, 2,3,5,6-tetrafluorothiophenol (TFTP), 4-(trifluoromethyl)thiophenol (TFMTP), 3,5-bis(trifluoromethyl)benzenethiol (BTFMBT) and 3,3,4,4,5,5,6,6,7, 7,8,8,9,9,10,10,10-heptadecafluoro-decane-1-thiol (HDFDT), were investigated. Modification was confirmed using attenuated total reflectance infrared spectroscopy; Raman mapping demonstrated that modification was homogenous on the macroscopic scale. The influence of fluorination on surface hydrophobicity was studied by contact angle analysis. The effect on microbial adherence was examined using Pseudomonas aeruginosa and Staphylococcus aureus.

KEY FINDINGS: The resultant changes in contact angle relative to control PVC ranged from -4 degrees to +14 degrees . In all cases, adherence of P. aeruginosa and S. aureus was significantly reduced relative to control PVC, with adherence levels ranging from 62% and 51% for TFTP-modified PVC to 32% and 7% for TFMTP-modified PVC.

CONCLUSIONS: These results demonstrate an important method in reducing the incidence of bacterial infection in PVC medical devices without compromising mechanical properties.

Vaginal delivery of the recombinant HIV-1 clade-C trimeric gp140 envelope protein CN54gp140 within novel rheologically structured vehicles elicits specific immune responses

Rheologically structured vehicle (RSV) gels were developed as delivery systems for vaginal mucosal vaccination with an HIV-1 envelope glycoprotein (CN54gp140). RSVs comprised a mucoadhesive matrix forming and vaginal fluid absorbing polymer. The mucoadhesive and rheological properties of the RSVs were evaluated in vitro, and the distribution, antigenicity and release of CN54gp140 were analysed by ELISA. CN54gp140 was uniformly distributed within the RSVs and continuously released in vitro in an antigenically intact form over 24 h. Vaginal administration to rabbits induced specific serum IgG, and IgG and IgA in genital tract secretions. The RSVs are a viable delivery modality for vaginal immunization.

Characterisation of fluidised bed granulation processes using in situ Raman spectroscopy

Previous work by the authors Walker et al. [2007b. Fluidised bed characterisation using Raman spectroscopy: applications to pharmaceutical processing. Chemical Engineering Science 62, 3832–3838] illustrated that Raman spectroscopy could be used to provide 3-D maps of the concentration and chemical structure of particles in motion in a fluidised bed, within a relatively short (120 s) time window. Moreover, we reported that the technique, as outlined, has the potential to give detailed in-situ information on how the structure and composition of granules/powders within the fluidised bed (dryer or granulator) vary with the position and evolve with time. In this study we extended the original work by shortening the time window of the Raman spectroscopic analysis to 10 s, which has allowed the in-situ real-time characterisation of a fluidised bed granulation process. Here we show an important new use of the technique which allows in-situ measurement of the composition of the material within the fluidised bed in three spatial dimensions and as a function of time. This is achieved by recording Raman spectra using a probe positioned within the fluidised bed on a long-travel x–y–z stage. In these experiments the absolute Raman intensity is used to provide a direct measure of the amount of any given material in the probed volume, i.e. a particle density. Particle density profiles have been calculated over the granulation time and show how the volume of the fluidised bed decreases with an increase mean granule size. The Raman spectroscopy analysis indicated that nucleation/coalescence in this co-melt fluidised hot melt granulation system occurred over a relatively short time frame (t<30 s). The Raman spectroscopic technique demonstrated accurate correlation with independent granulation experiments which provided particle size distribution analysis. The similarity of the data indicates that the Raman spectra accurately represent solids ratios within the bed, and thus the techniques quantitative capabilities for future use in the pharmaceutical industry.