The expression of oestrogen receptor (ER)-beta and its variants, but not ERalpha, in adult human mammary fibroblasts

Whilst oestrogen receptor (ER)-alpha and ERbeta have been shown to be important in the development of the mammary gland, the cell-specific expression pattern of these two receptors within the human breast is not clear. Although it is well established that in the developing rodent mammary gland stromal ERalpha mediates the secretion of growth factors which stimulate the proliferation of the ductal epithelium, the expression of ERalpha in human adult breast stromal fibroblasts is controversial, and the expression of ERbeta has not been properly defined. In the present study, we have evaluated the expression of ERalpha and ERbeta by immunohistochemistry in normal tissue samples, and in purified human breast fibroblasts by Western blotting, RT-PCR analysis and ligand-binding sucrose gradient assay. Our data clearly demonstrated that ERbeta variants, including ERbeta1, ERbeta2, ERbeta5, ERbetadelta and ERbetains, but not ERalpha, are expressed in human adult mammary fibroblasts. These results are supported by the findings that an ERbeta-selective ligand, BAG, but not the ERalpha high-affinity ligand oestradiol, can induce fibroblast growth factor-7 release and activate transcription from an oestrogen-responsive element promoter in these adult human mammary fibroblasts. Together, these observations revealed that, in the adult breast and in breast cancer, the proliferative signals derived from the stroma of adult mammary glands in response to oestrogen are not mediated by ERalpha and provide new insights into the nature of stromal-epithelial interactions in the adult mammary gland. In addition, the expression of these ERbeta variants in cells where there is no ERalpha suggested that these ERbeta splice forms may have functions other than that of modulating ERalpha activity.

Commentary on "Mechanical properties of monodomain side-chain nematic elastomers" by P. Martinoty, P. Stein, H. Finkelmann, H. Pleiner and H.R. Brand

We discuss the background to static and dynamic soft elasticity. The evidence in the static case and the symmetry basis for soft and semi-soft elasticity is well understood. By contrast the dynamic analogy is less clear. Lack of clean time scale separation clouds the interpretation of director relaxation keeping up, or not, with imposed strains. However, the reduction in modulus between geometries obtaining at low frequencies and being lost at high frequencies confirms that director reaction indeed determines dynamical semi-softness.

Photoinduced deformations of beams, plates, and films

Photoresponsive solids such as nematic photoelastomers can undergo large deformations induced by light absorbed into rodlike molecules which bend and disrupt liquid crystal order. Significant variation of photoabsorption through the solid leads to nonuniform elastic deformations such as bending of beams and plates and pitting of layers. Such effects are also found in the presence of inhomogeneous thermal or swelling fields in solids or gels. We analyze the small deflection limit of these problems and show that beams made of these materials can have two elastically neutral planes, and that plates of these materials have a typical saddle shape. We also give a scaling analysis of the elasticity of photoinduced mounds and pits and speculate on their applications.

Reliability of routine disc susceptibility testing by the British Society for Antimicrobial Chemotherapy (BSAC) method

OBJECTIVES

To ascertain the agreement between MICs determined at a central laboratory, and susceptible, intermediate and resistant categorizations based on zone diameters recorded at diagnostic laboratories using the BSAC standardized method.

METHODS

Standardized disc susceptibility tests were performed at sentinel laboratories in three surveys, with MIC tests performed on the collected isolates at a reference laboratory. The organisms comprised over 3300 Enterobacteriaceae, Acinetobacter spp., pseudomonads, staphylococci and enterococci, with over 29 000 antibiotic/organism tests in total.

RESULTS

More than 90% of the antibiotic/organism combinations classed as susceptible by disc tests in the sentinel laboratories were confirmed by MIC testing. Disagreements were more frequent where disc tests indicated resistance, with half of the piperacillin/tazobactam resistance and one-third of the cephalosporin resistance found in Enterobacteriaceae by disc tests not being confirmed, and with three-quarters of teicoplanin resistance in enterococci not confirmed. None of the few apparent cases of meropenem resistance in Enterobacteriaceae or linezolid, quinupristin/dalfopristin or vancomycin resistance in staphylococci were confirmed by MIC testing. When disagreements were found between disc- and MIC-based categorization, MICs were commonly, although not invariably, one to three doubling dilutions above or below the breakpoint. However, many of the disagreements where MICs were three or more dilutions from the breakpoint were not seen when disc tests were repeated in the central laboratory.

CONCLUSIONS

The BSAC disc method seems adequate for confirming susceptibility to guide therapy and to monitor resistance trends. Nevertheless, there must be concern about the over-estimation of many resistances, and frequent zone:MIC disagreements for isolates with borderline susceptibility.

Reflectivity of cholesteric liquid crystals with spatially varying pitch

Solids with spatially varying photonic structure offer gaps to light of a wider range of frequencies than do simple photonic systems. We solve numerically the field distribution in a cholesteric with a linearly varying inverse pitch (helical wavevector) using equations we derive for the general case. The simple idea that the position where the Bragg condition is locally satisfied is where reflection takes place is only true in part. Here, reflection is due to a region where the waves are forced to become evanescent, and the rate of variation of structure determines over which distance the waves decay and therefore how complete reflection is. The approximate local Bragg-de Vries schemes are shown to break down in detail at the edges of the gap, and an analytical estimate is given for the transmission coefficient.

Survey of resistance of Pseudomonas aeruginosa from UK patients with cystic fibrosis to six commonly prescribed antimicrobial agents

BACKGROUND

Respiratory infection with Pseudomonas aeruginosa is very common in patients with cystic fibrosis (CF) but antimicrobial resistance rates of CF isolates across the UK are largely unknown.

METHODS

The susceptibility of 417 CF patient isolates of P aeruginosa from 17 hospitals to six commonly prescribed antibiotics were examined. Isolates were tested by an agar break point dilution method and E-tests according to British Society of Antimicrobial Chemotherapy guidelines. Genotyping of isolates was performed by XbaI DNA macrorestriction and pulsed field gel electrophoresis.

RESULTS

38% of isolates were susceptible to all of the agents tested; almost half were resistant to gentamicin compared with ceftazidime (39%), piperacillin (32%), ciprofloxacin (30%), tobramycin (10%), and colistin (3%). Approximately 40% were resistant to two or more compounds with ceftazidime in combination with gentamicin, piperacillin or ciprofloxacin being the most common cross resistances. Resistance rates were generally similar to those reported recently from the USA and Germany. A selection of resistant isolates proved to be predominantly genotypically distinct by XbaI DNA macrorestriction but six pairs from three centres had similar genotypes.

CONCLUSIONS

The level of resistance to front line antipseudomonal agents, with the exception of colistin, is disturbingly high. The prudent use of antimicrobial drugs and closer monitoring of accumulation of resistant strain populations should be actively considered.

Susceptibility of Gram-positive bacteria from ICU patients in UK hospitals to antimicrobial agents

Microbiologists in 25 sentinel laboratories were each asked to refer up to 100 clinically-significant Gram-positive bacteria isolated from consecutive intensive care unit (ICU) patients. A total of 1595 isolates were collected from patients in 23 hospitals; these included Staphylococcus aureus (47.6%), coagulase-negative staphylococci (CNS) (30.6%), enterococci (14.3%), pneumococci (2.8%) and other streptococci (3.5%). A few coryneforms, other bacilli and a Nocardia sp. were also collected. Rates of oxacillin resistance among S. aureus and CNS isolates were 59.3 and 78.5%, respectively. Vancomycin-resistant S. aureus were not detected, although two isolates (0.3%) were resistant to teicoplanin [minimum inhibitory concentrations (MICs) 8 mg/L]. In contrast, 13.7% of CNS were teicoplanin resistant (MICs 8-32 mg/L) and 1.2% were resistant to vancomycin. Among the enterococci, 72.5% were Enterococcus faecalis and 24.5% were Enterococcus faecium, the remainder including isolates of Enterococcus casseliflavus or Enterococcus gallinarum. Eighteen percent of E. faecium isolates were vancomycin-resistant, compared with only 3% of E. faecalis isolates. Rates of high-level gentamicin resistance in E. faecalis and E. faecium were 40 and 25%, respectively. Nine percent of pneumococci and streptococci were resistant to penicillin, with 7 and 11%, respectively, resistant to erythromycin. None of the isolates showed resistance to linezolid, with the MICs for the entire study population falling in the range of 0.5-4 mg/L.

In vitro activity of piperacillin/tazobactam and other broad-spectrum antibiotics against bacteria from hospitalised patients in the British Isles

Piperacillin/tazobactam is used for empirical therapy of severe and complex infections. We assessed its activity, 9 years after launch, against consecutive, clinically significant isolates from in-patients in UK and Ireland. Standardised disc susceptibility tests were performed on 5031 isolates at 28 hospitals. For quality assurance purposes, 5% of these isolates were collected centrally for MIC tests, as were those with exceptional resistances. Compared with a similar pre-launch survey in 1991, there were major increases in the proportions of Staphylococcus aureus, Pseudomonas aeruginosa, beta-haemolytic streptococci and Enterococcus faecium isolates collected, balanced by decreases in Escherichia coli, Proteus mirabilis and coagulase-negative staphylococci. These changes in species prevalence mostly favoured organisms with inherent resistance(s) or-in the case of S. aureus-reflected the massive increase of MRSA, up from 0.7% of all isolates in 1991 to 14.8% in 2001. Based on the disc tests, piperacillin/tazobactam retained activity against 87% of Enterobacteriaceae isolates, 95% of P. aeruginosa, 99% of streptococci and 96% of Enterococcus faecalis. Resistance nevertheless had increased since 1991 in E. coli from 4 to 10%, Klebsiella spp. (5 to 21%) and in AmpC-inducible Enterobacteriaceae (17 to 23%), though not in P. mirabilis or P. aeruginosa. MIC tests confirmed most of the piperacillin/tazobactam resistance found by disc tests in Enterobacter spp., but indicated susceptibility for about half of the E. coli isolates recorded as resistant in disc tests. This situation might be remedied by reducing the zone breakpoint, but this would increase the "false susceptible" rate unacceptably. Thus, if disc tests suggest that an isolate is marginally resistant to piperacillin/tazobactam and the drug is sought as therapy, it is recommended that MIC be determined with, e.g., an Etest.

Liquid crystalline elastomers: dynamics and relaxation of microstructure

The equilibrium mechanical response of nematic elastomers can be soft or hard depending on the relation between the imposed strains and the nematic director, in particular, if the local nematic director is able to respond by rotating. The dynamical response proves to be equally unusual. We examine the linear dynamic mechanical response of monodomain nematic elastomers under shear and the aspects of time-temperature superposition of the dynamical data across phase-transition regions. In the low-frequency region of the master curves, one finds a dramatic reduction of rubber plateau modulus and the rise in internal dissipation: in the shear geometries compatible with dynamic soft elasticity. Power-law variation of the storage modulus with frequency G' proportional, variant omega(a) agrees very well with the results of static stress relaxation, where each relaxation curve obeys the analogous power law G' proportional, variant t(-a) in the corresponding region of long times and temperatures.

Isotropic-to-cholesteric transition in liquid crystal elastomers

A liquid crystal elastomer tries to spontaneously elongate on entering the locally nematic phase, but may have to twist to reduce its Frank elastic energy. The extremes are a conventional, transverse cholesteric structure (where it reduces its Frank energy), and a uniformly aligned state (where it can maximally spontaneously extend and reduce its elastic energy). Between these it can adopt a conical state where there is also bend but equally a partial satisfaction of the elastic requirements. A line of first-order transitions between conical and transverse states ends and becomes a line of second-order transitions, depending on chain anisotropy, the ratio of the Frank bend and twist constants, and on the elastic modulus reduced by the bend energy. Continuous and discontinuous variation of cone angles, and spontaneous elongations and shears are given, as are analytic forms for the singular variation of director as cones are lost to the transverse state. The variation of the multicritical point with the ratio of Frank constants is also given.

Emerging linezolid-resistant Enterococcus faecalis and Enterococcus faecium isolated from two Austrian patients in the same intensive care unit

Of two patients in the same intensive care unit who were treated with linezolid, one yielded linezolid-resistant Enterococcus faecalis, whereas the other yielded linezolid-resistant Enterococcus faecium. In each case, molecular typing indicated that the resistant isolates were related to linezolid-susceptible isolates from the same patient, but differed from them by the same G2576U ribosomal RNA mutation. This is the first clinical case report of emerging resistance to linezolid among Enterococcus faecalis and also the first report of resistance involving vancomycin-susceptible rather than vancomycin-resistant enterococci. The linezolid-resistant isolates showed cross-resistance to the experimental oxazolidinone AZD2563, suggesting that oxazolidinone resistance might be a class effect.

Uniaxial and biaxial soft deformations of nematic elastomers

We give a geometric interpretation of the soft elastic deformation modes of nematic elastomers, with explicit examples, for both uniaxial and biaxial nematic order. We show the importance of body rotations in this nonclassical elasticity and how the invariance under rotations of the reference and target states gives soft elasticity (the Golubovic and Lubensky theorem). The role of rotations makes the polar decomposition theorem vital for decomposing general deformations into body rotations and symmetric strains. The role of the square roots of tensors and that of finding explicit forms for soft deformations (the approach of Olmsted) are discussed in this context.

Photonic band structure of cholesteric elastomers

We calculate the photonic band structure along and oblique to the helix axis of cholesteric elastomers. They are highly deformable, self-assembling systems. They display brilliantly colored reflections and lasing owing to stop bands in their photonic band structure. This band structure varies sensitively and extensively with strain. We show how additional stop bands open up and how they all shift in frequency. We predict a "total" stop band, that is, for both circular polarizations and show analytically how stop bands scale with strain. The extension of stop bands to a range of angles thereby creates pseudogaps, and the relevance to low-threshold lasing is discussed.