Biased allosteric modulation at the CaS receptor engendered by structurally diverse calcimimetics.

BACKGROUND AND PURPOSE: Clinical use of cinacalcet in hyperparathyroidism is complicated by its tendency to induce hypocalcaemia, arising partly from activation of calcium-sensing receptors (CaS receptors) in the thyroid and stimulation of calcitonin release. CaS receptor allosteric modulators that selectively bias signalling towards pathways that mediate desired effects [e.g. parathyroid hormone (PTH) suppression] rather than those mediating undesirable effects (e.g. elevated serum calcitonin), may offer better therapies. EXPERIMENTAL APPROACH: We characterized the ligand-biased profile of novel calcimimetics in HEK293 cells stably expressing human CaS receptors, by monitoring intracellular calcium (Ca(2+) i ) mobilization, inositol phosphate (IP)1 accumulation, ERK1/2 phosphorylation (pERK1/2) and receptor expression. KEY RESULTS: Phenylalkylamine calcimimetics were biased towards allosteric modulation of Ca(2+) i mobilization and IP1 accumulation. S,R-calcimimetic B was biased only towards IP1 accumulation. R,R-calcimimetic B and AC-265347 were biased towards IP1 accumulation and pERK1/2. Nor-calcimimetic B was unbiased. In contrast to phenylalkylamines and calcimimetic B analogues, AC-265347 did not promote trafficking of a loss-of-expression, naturally occurring, CaS receptor mutation (G(670) E). CONCLUSIONS AND IMPLICATIONS: The ability of R,R-calcimimetic B and AC-265347 to bias signalling towards pERK1/2 and IP1 accumulation may explain their suppression of PTH levels in vivo at concentrations that have no effect on serum calcitonin levels. The demonstration that AC-265347 promotes CaS receptor receptor signalling, but not trafficking reveals a novel profile of ligand-biased modulation at CaS receptors The identification of allosteric modulators that bias CaS receptor signalling towards distinct intracellular pathways provides an opportunity to develop desirable biased signalling profiles in vivo for mediating selective physiological responses.

Evidence of compositional differences between the extracellular and intracellular DNA of a granular sludge biofilm.

AIMS: Extracellular polymeric substances (EPS) are an important component of microbial biofilms, and it is becoming increasingly apparent that extracellular DNA (eDNA) has a functional role in EPS. This study characterizes the eDNA extracted from the novel activated sludge biofilm process of aerobic granules. METHODS AND RESULTS: Exposing the sludge to cation exchange resin (CER) was used for the extraction of eDNA and intracellular DNA (iDNA) from aerobic granules. This was optimized for eDNA yield while causing minimal cell lysis. We then compared the DNA composition of these extractions using randomly amplified polymorphic DNA (RAPD) fingerprinting and PCR-based denaturing gradient-gel electrophoresis (DGGE). Upon the analysis of the genomic DNA and the 16S rRNA genes, differences were detected between the sludge biofilm eDNA and iDNA. CONCLUSIONS: Different bacteria within the biofilm disproportionally release DNA into the EPS matrix of the biofilm. SIGNIFICANCE AND IMPACT OF THE STUDY: The findings further the idea that eDNA has a functional role in the biofilm state, which is an important conceptual information for industrial application of biofilms.

Mortality following exenteration for malignant tumours of the orbit.

BACKGROUND: Orbital exenteration is a rare, but disfiguring procedure reserved for the treatment of locally invasive malignancy or potentially life threatening orbital neoplasms, when less destructive techniques are inadequate. The authors report their experience and analyses of 64 cases of orbital exenteration performed over a 13 year period, looking specifically at key factors affecting mortality associated with such a destructive surgical procedure. METHODS: Records were reviewed retrospectively of all patients who had undergone exenteration of the orbit from 1 January 1991 to 1 April 2004 inclusive, at the Manchester Royal Eye Hospital. In all cases of deceased individuals, the cause of death was determined by liaison with the general practitioner and local health authority. Duplicate death certificates were requested for all deceased patients from the Registrar for Births, Deaths, and Marriages, Southport, UK. Kaplan-Meier analysis was used to estimate survival following exenteration. RESULTS: Overall, 1 year survival post-exenteration was high at 93%. After 3 years this had fallen to 67%, followed by 57% after 5 years, and 37% at 10 years. 13 patients died as a direct result of the orbital tumour. A further nine died of unrelated medical conditions, and two patients succumbed to malignant processes originating elsewhere in the body. There was no difference in survival rate at 3 years (p=0.99) and 5 years (p=0.454) between those with clear resection margins and those without. CONCLUSION: In this study it was found that there was an overall mortality rate of 38% over 12 years. The presence of clear surgical margins, although reassuring for the surgeon, should not be regarded as an indication of cure. However, an overall 1 year survival of 93% and a 10 year survival of 37% are reassuring in that a proportion of individuals achieve surgical cure following exenteration. 38% of patients died as a result of other medical causes over the 12 year follow up.

Orbital exenteration: a 13 year Manchester experience.

BACKGROUND/AIMS: Orbital exenteration is a psychologically and anatomically disfiguring procedure reserved for the treatment of potentially life threatening malignancies or relentlessly progressive conditions unresponsive to other treatments. In this study the authors aimed to review their experience with exenteration, including indications, outcomes, and reasons for the increased rate of exenterations over the past 15 months. METHOD: This retrospective study reviewed operating department records via a computerised database to identify all patients who had undergone exenteration of the orbit from 1 January 1991 to 1 April 2004 inclusive, at the Manchester Royal Eye Hospital. Where case records were unavailable, attempts were made to obtain patient data from general practitioners, local health authorities, and referring hospitals. RESULTS: 69 orbits of 68 patients were identified. The mean age of the cohort was 68.2 years, with 33 males and 35 females having undergone exenterations. In total, 31 patients had previously undergone treatments undertaken by the referring specialty with a mean time from the primary procedure to exenteration of 115 months. 14 different tumours were encountered, of which basal cell carcinoma (28), melanoma (10), sebaceous cell carcinoma (nine), and squamous cell carcinoma (six) were the most common. An increasing incidence was observed in cases of BCCs requiring exenteration. 30 patients received orbital prosthesis within an 11 month period post-exenteration. CONCLUSION: Exenteration is a procedure performed with increasing frequency in this unit over the past 15 months, the majority the result of BCCs. A large proportion of these exenterations had undergone previous treatments under a variety of non-ophthalmic specialties in other units. Exenterations are disfiguring procedures that may, therefore, be reduced in incidence by aggressive removal at the time of primary removal. Once performed, the cosmetic rehabilitation is long, with multiple postoperative visits, independent of the method used to close the orbital defect.

Strategies for containing drug costs: implications for a Medicare benefit.

As policymakers consider adding a prescription drug benefit to Medicare, cost containment will be an important issue. This article discusses strategies to hold down the prices paid for prescription drugs. Within the private sector these include the use of formularies, the emergence of pharmaceutical benefit management companies, and the expansion of mail order pharmacies. In the Federal Government, costs are contained by the Medicaid drug rebate and the Federal Supply Schedule (FSS) of prices. Since Medicare beneficiaries constitute a large share of the prescription drug market, getting access to FSS prices may not be feasible. A flat rebate is one alternative.