Pitfalls in Cutaneous Melanoma Diagnosis and the Need for New Reliable Markers.

Cutaneous melanoma is one of the most aggressive forms of skin cancer, with the development of advanced stage disease resulting in a high rate of patient mortality. Accurate diagnosis of melanoma at an early stage is essential to improve patient outcomes, as this enables treatment before the cancer has metastasised. Histopathologic analysis is the current gold standard for melanoma diagnosis, but this can be subjective due to discordance in interpreting the morphological heterogeneity in melanoma and other skin lesions. Immunohistochemistry (IHC) is sometimes employed as an adjunct to conventional histology, but it remains occasionally difficult to distinguish some benign melanocytic lesions and melanoma. Importantly, the complex morphology and lack of specific biomarkers that identify key elements of melanoma pathogenesis can make an accurate confirmation of diagnosis challenging. We review the diagnostic constraints of melanoma heterogeneity and discuss issues with interpreting routine histology and problems with current melanoma markers. Innovative approaches are required to find effective biomarkers to enhance patient management.

A thermodynamic and kinetic analysis of human epidermal penetration of phenolic compounds: II. Maximum flux and solute diffusion through stratum corneum lipids.

Warming the skin is a key means of promoting solute permeation through the skin. Changes in solute permeation associated with variations in skin temperature also assist in understanding the mechanism by which solutes permeate the skin. However, few studies have considered the relative impact of temperature on the main determinants of the maximum flux for a solute across the skin, the solubility of a solute and its diffusivity in the stratum corneum. In this study, we quantified for the first time the thermodynamics associated with the maximum skin fluxes for a series of phenolic compounds of similar size but with varying lipophilicity (defined by the logarithms of their octanol/water partition coefficient, logP). These studies were undertaken using aqueous donor solutions (along with testosterone as a reference solute) across human epidermal membranes in vertical Franz diffusion cells at 4 °C, 24 °C and 37 °C with intermittent receptor sampling and volume replacement over 24 h. Kinetic and thermodynamic analyses included the estimation of the stratum corneum (SC) apparent SC diffusivity from the SC maximum fluxes and SC solubilities and the associated activation energies, enthalpies and entropies for diffusion. The key findings were that the differences in the maximum flux of phenolic compounds varying in lipophilicity mainly arose from differences in SC solubility at the various temperatures and that, at the highest temperature, SC permeability and SC diffusion were affected by SC lipid fluidisation and that variations in SC - water partitioning enthalpies explain some of the previously low activation energies for permeation of the more lipophilic phenols. Higher enthalpies for diffusion were seen for solutes with addition hydrogen bonding capacity and the highest negative entropy was observed with the more compact solutes. Various relationships between the derived thermodynamic parameters were explored and interpreted in a proposed model for solute partitioning into and permeation through the SC intercellular lipid lamellae.

Thermodynamic and kinetic analysis of human epidermal penetration of phenolic compounds: I. Stratum corneum solubility and partitioning.

Warming of the skin is now an accepted means of promoting skin permeation. Accordingly, the usually quite onerous thermodynamic studies on solute transport through the skin have practical applications. Phenolic compounds permeate through the skin by partitioning into and diffusing through the stratum corneum (SC) intercellular lipids, with their size being the main determinant of their maximal solute flux through skin. This paper sought to characterise the enthalpic and entropic changes associated with the solubility and equilibrium partitioning into the human SC of a series of phenols similar in size but with differing log P from aqueous vehicles. The solubilities of 9 phenolic compounds, covering a range of polarities, were determined in water and SC following 72 h at 4, 24, 32 and 37 °C which allowed the estimation of the SC-water partition coefficients. Van't Hoff plots were then used to estimate the enthalpies and entropies for the SC solubility, water solubility and SC partitioning of phenols. In addition, partition coefficients of 3 of the 9 phenols from mineral oil into hydrated and dehydrated SC were measured at the same temperatures. Van't Hoff plots were then used to estimate the enthalpies and entropies for the SC solubility, water solubility and SC partitioning of phenols from the oil. The SC solubility for the polar phenols increased more with temperature than the non-polar phenols, with the SC-water partition coefficients increasing with temperature for the polar phenols but decreasing with temperature for the non-polar phenols. Thermodynamic analyses suggest that, while enthalpy and entropy effects are involved in the SC partitioning of the non-polar solutes, the SC partitioning of the polar phenols were almost entirely entropy driven. The resultant thermodynamic parameters are consistent with the polar phenols being mainly associated with the SC polar head groups whereas the nonpolar phenols were more likely to be located in the interior interface SC lipid region adjacent to the polar head groups. Further, hydrating the SC led to an increase in the enthalpy of partitioning for both the polar and non-polar phenols studied. The estimated entropy of the partitioning for solutes from dehydrated SC suggests this is not only a hydrophobic effect in water but that the partitioning arises from the nature of phenolic compound - SC intercellular lipid interactions and SC intercellular lipid entropy. This partitioning process is dominated more by the extent of interaction between the SC and solute than the hydrophobic effect in water and is likely to be even greater above the SC lipid phase transition at around 36 °C for hydrated epidermal membranes.

Bio-enabling strategies to mitigate the pharmaceutical food effect: A mini review.

The concomitant administration of oral drugs with food can result in significant changes in bioavailability, leading to variable pharmacokinetics and considerable clinical implications, such as over- or under-dosing. Consequently, there is increasing demand for bio-enabling formulation strategies to reduce variability in exposure between the fasted and fed state and/or mitigate the pharmaceutical food effect. The current review critically evaluates technologies that have been implemented to overcome the positive food effects of pharmaceutical drugs, including, lipid-based formulations, nanosized drug preparations, cyclodextrins, amorphisation and solid dispersions, prodrugs and salts. Additionally, improved insight into preclinical models for predicting the food effect is provided. Despite the wealth of research, this review demonstrates that application of optimal formulation strategies to mitigate the positive food effects and the evaluation in preclinical models is not a universal approach, and improved standardisation of models to predict the food effects would be desirable. Ultimately, the successful reformulation of specific drugs to eliminate the food effect provides a panoply of advantages for patients with regard to clinical efficacy and compliance.

Chitosan nanoparticles facilitate improved intestinal permeation and oral pharmacokinetics of the mast cell stabiliser cromoglycate.

Cromoglycate is a mast cell stabiliser typically administered via inhalation or intranasally for the treatment of allergy-based respiratory issues. Oral dosing of cromoglycate remains challenging due to its high solubility but low permeability across epithelial membranes in the gastrointestinal tract: effective formulation strategies are clearly needed. Here, we investigate and preclinically develop chitosan-cromoglycate complexes and associated nano/microparticle formulations with muco-adhesive and permeation enhancing capabilities to overcome the biopharmaceutical challenges for oral dosing.The synthesized complexes were optimized with respect to chitosan grade, particle size, and drug loading and demonstrated up to a 9.3-fold enhancement in permeability across a Caco-2 monolayer for chitosan-cromoglycate particles, compared to the pure drug. This increased intestinal permeability led to improved pharmacokinetic performance of cromoglycate, e.g. up to 1.82-fold increase in relative oral bioavailability when dosed to Sprague-Dawley rats in a fasted state. These findings confirm the potential for chitosan particles to serve as an effective oral delivery vehicle for cromoglycate, with additional formulation optimization presenting the opportunity to reduce dosing frequency for treatment of allergy-based respiratory ailments.

Simultaneous LC-MS/MS quantification of oxycodone, tramadol and fentanyl and their metabolites (noroxycodone, oxymorphone, O- desmethyltramadol, N- desmethyltramadol, and norfentanyl) in human plasma and whole blood collected via venepuncture and volumetric absorptive micro sampling.

INTRODUCTION: A range of opioids are commonly prescribed to manage chronic pain, but individual patient responses vary greatly, especially in older populations. One source of that variability are differences in absorption, metabolism and excretion, i.e. pharmacokinetics. Blood, plasma and serum concentrations of opioids allow that variability to be quantified and may be used to optimise opioid dosing. As an aid to that process, there is an unmet need to rapidly quantify several opioids and their metabolites in a single analytical method. AIMS: To develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantification of tramadol, oxycodone, fentanyl and their major metabolites in various human matrices. METHODS: Sample preparation involved adding three deuterated internal standards followed by protein precipitation with 100 % acetonitrile, evaporation and reconstitution. Separation of analytes via LC was achieved on a reversed phase column via binary gradient elution using 0.005 % formic acid in water and 100 % acetonitrile as mobile phases. Analytes were detected via MS/MS with multiple reaction monitoring (MRM). RESULTS: The method was accurate with the inter-day and intra-day accuracy of quality control samples (QCs) below 15 %. It was also precise with inter-day and intra-day coefficient of variation below 15 %. The lower limit of quantification (LLOQ) was 0.2 ng/mL for all analytes except tramadol and its metabolites, where the LLOQ was 10 ng/mL. Recovery was greater than 88 % for all analytes, except for O-desmethyltramadol (81 %). Analytes were stable over four freeze-thaw cycles, for 24 h on the bench top and for 24 h post-preparation. The inter- and intra-day variability of concentrations determined in blood and plasma were within 84-124%, whereas the inter- and intra-day variability for blood samples prepared using volumetric absorptive micro-sampling (VAMS) compared to those prepared from whole blood ranged between 83-122%. CONCLUSION: A LC-MS/MS method is described that is able to accurately and precisely quantify a number of commonly prescribed opioids and their major metabolites in plasma and whole blood, including whole blood collected using VAMS.

Efficacy and safety of statins in ethnic differences: a lesson for application in Indigenous Australian patient care.

Although statins are effective in treating high cholesterol, adverse effects do occur with their use. Efficacy and tolerability vary among statins in different ethnic groups. Indigenous Australians have a high risk for cardiovascular and kidney diseases. Prescribing statins to Indigenous Australians with multi-morbidity requires different strategies to increase efficacy and reduce their toxicity. Previous studies have reported that Indigenous Australians are more susceptible to severe statin-induced myopathies. However, there is a lack of evidence in the underlying genetic factors in this population. This review aims to identify: inter-ethnic differences in the efficacy and safety of statins; major contributing factors accounting for any identified differences; and provide an overview of statin-induced adverse effects in Indigenous Australians.

Population pharmacokinetic model of subcutaneous fentanyl in older acute care patients.

PURPOSE: Subcutaneous fentanyl injection is commonly prescribed to manage acute pain in older patients; however, there is a gap in the literature describing the pharmacokinetic parameters for this route of administration in this population. The aim of this study was to develop and evaluate a population pharmacokinetic model for subcutaneous fentanyl injection in older patients. METHODS: Twenty-one patients who received subcutaneous fentanyl injections (50 to 75 µg) were recruited. Fentanyl concentrations were determined using a validated liquid chromatography/tandem mass spectrometry method. A population pharmacokinetic model was developed using non-linear mixed-effects modelling. A base model was selected based on the Akaike information criterion. Age, sex, body weight, number of previous fentanyl doses, number of prescribed medications, creatinine clearance, Charlson Comorbidity Index, Identification of Seniors at Risk score and concurrent use of CYP3A4 inhibitors were covariates considered for inclusion. A p value of < 0.05 was considered statistically significant for inclusion of covariates in the final model by stepwise addition. The simulation performance of the model was assessed by visual predictive check. RESULTS: A one-compartment, first-order absorption with lag time and linear elimination model was the best to fit to the fentanyl concentration data. The absorption rate constant was 0.136 h-1 (between subject variability (BSV), 46%), lag time 0.66 h (BSV 51%), apparent volume of distribution 6.28 L (BSV 30%), and apparent clearance 16.3 L.h-1 (BSV 54%). The Charlson Comorbidity Index was the only covariate included in the final model, where a higher value of the index increased fentanyl exposure and Cmax. CONCLUSION: This is the first report of subcutaneous fentanyl population pharmacokinetic model to evaluate fentanyl pharmacokinetic in older patients. The between subject variability in clearance and subcutaneous absorption rate was relatively high, and some patients recorded high fentanyl concentrations in the context of their titration to effect.

Protective Effect of Isothiocyanates from Cruciferous Vegetables on Breast Cancer: Epidemiological and Preclinical Perspectives.

BACKGROUND: The effect of cruciferous vegetable intake on breast cancer survival is controversial at present. Glucosinolates are the naturally occurring constituents found across the cruciferous vegetables. Isothiocyanates are produced from the hydrolysis of glucosinolates and this reaction is catalysed by the plant-derived enzyme myrosinase. The main Isothiocyanates (ITCs) from cruciferous vegetables are sulforaphane, benzyl ITC, and phenethyl ITC, which had been intensively investigated over the last decade for their anti-breast cancer effects. OBJECTIVE: The aim of this article is to systematically review the evidence from all types of studies, which examined the protective effect of cruciferous vegetables and/or their isothiocyanate constituents on breast cancer. METHODS: A systematic review was conducted in Pubmed, EMBASE, and the Cochrane Library from inception to 27 April 2020. Peer-reviewed studies of all types (in vitro studies, animal studies, and human studies) were selected. RESULTS: The systematic literature search identified 16 human studies, 4 animal studies, and 65 in vitro studies. The effect of cruciferous vegetables and/or their ITCs intake on breast cancer survival was found to be controversial and varied greatly across human studies. Most of these trials were observational studies conducted in specific regions, mainly in the US and China. Substantial evidence from in vitro and animal studies was obtained, which strongly supported the protective effect of sulforaphane and other ITCs against breast cancer. Evidence from in vitro studies showed that sulforaphane and other ITCs reduced cancer cell viability and proliferation via multiple mechanisms and pathways. Isothiocyanates inhibited cell cycle, angiogenesis and epithelial mesenchymal transition, as well as induced apoptosis and altered the expression of phase II carcinogen detoxifying enzymes. These are the essential pathways that promote the growth and metastasis of breast cancer. Noticeably, benzyl ITC showed a significant inhibitory effect on breast cancer stem cells, a new dimension of chemo-resistance in breast cancer treatment. Sulforaphane and other ITCs displayed anti-breast cancer effects at variable range of concentrations and benzyl isothiocyanate appeared to have a relatively lower inhibitory concentration IC50. The mechanisms underlying the cancer protective effect of sulforaphane and other ITCs have also been highlighted in this article. CONCLUSION: Current preclinical evidence strongly supports the role of sulforaphane and other ITCs as potential therapeutic agents for breast cancer, either as adjunct therapy or combined therapy with current anti-breast cancer drugs, with sulforaphane displaying the greatest potential.

Opioid prescribing and risk of drug-opioid interactions in older discharged patients with polypharmacy in Australia.

Background Opioids are commonly prescribed to managing chronic pain in older persons. However, these patients are often at risk of drug-opioid interactions due to polypharmacy. Objectives To identify the prevalence of opioid prescribing and drug-opioid interactions in poly-medicated older patients and factors associated with opioid prescribing. Setting Patients were included if they were admitted to the Royal Adelaide Hospital between September 2015 and August 2016, aged ≥ 75 years and took ≥ 5 medications at discharge. Methods After ethics approval, data of were retrospectively collected from case notes. The Charlson Comorbidity Index and Drug Burden Index were determined and opioids were classified as strong or weak. The association between opioid use and concurrent medications was computed using logistic regression and the results presented as odds ratios (OR) and 95% confidence intervals (95% CI), adjusted for age, sex, Charlson Comorbidity Index, number of prescribed medications and modified-Drug Burden Index. Main outcome measure Association between concurrent medications and opioid prescribing. Results 15,000 geriatric admissions were identified, of which 1192 were included. A total of 283 (23.7%) patients were prescribed opioids, with oxycodone accounting for 56% of these prescriptions. Opioid users were prescribed more medications (11.2 vs. 9.0, P < 0.001) and had higher Drug Burden Index (1.2 vs. 0.14, P < 0.001) compared to non-users. Opioid use was associated with concurrent prescription of antiepileptics (OR = 1.7, 95% CI 1.1-2.6), and negatively associated with Charlson Comorbidity Index (OR = 0.9, 95% CI 0.8-0.98) and concurrent use of antipsychotics (OR = 0.5, 95% CI 0.3-0.9) and beta blocking agents (OR = 0.4, 95% CI 0.3-0.6). Conclusions Strong opioids were prescribed more often than weak opioids and opioid users presented with characteristics and concurrent medications which increased the risk of opioid related adverse drug effects.

Drug-Eluting Biodegradable Implants for the Sustained Release of Bisphosphonates.

Despite being one of the first-line treatments for osteoporosis, the bisphosphonate drug class exhibits an extremely low oral bioavailability (<1%) due to poor absorption from the gastrointestinal tract. To overcome this, and to explore the potential for sustained drug release, bioerodible poly(lactic acid) (PLA) and poly(D,L-lactide-co-glycolide) (PLGA) implants loaded with the bisphosphonate alendronate sodium (ALN) were prepared via hot-melt extrusion. The rate of drug release in vitro was modulated by tailoring the ratio of lactide to glycolide in the polymer and by altering the ALN-loading of the implants. All investigated implants exhibited sustained ALN release in vitro between 25 to 130 days, where implants of greater glycolide composition and higher ALN-loadings released ALN more rapidly. All PLGA implants demonstrated a sigmoidal release profile, characterised by an initial surface dissolution phase, followed by a period of zero-order drug diffusion, then relaxation or erosion of the polymer chains that caused accelerated release over the subsequent days. Contrastingly, the PLA implants demonstrated a logarithmic release profile, characterised by a gradual decrease in ALN release over time.

Copolymeric Micelles Overcome the Oral Delivery Challenges of Amphotericin B.

Classified as a Biopharmaceutical Classification System (BCS) class IV drug, amphotericin B (AmB) has low aqueous solubility and low permeability leading to low oral bioavailability. To improve these limitations, this study investigated the potential of AmB-loaded polymeric micelles (AmB-PM) to increase intestinal absorption. AmB-PM were prepared with polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol copolymer (Soluplus®) as a polymeric carrier and used a modified solvent diffusion and microfluidics (NanoAssemblr®) method. AmB-PM have a mean particle size of ~80 nm and are mono-disperse with a polydispersity index <0.2. The entrapment efficiency of AmB was up to 95% and achieved with a high drug loading up to ~20% (w/w) with a total amount of incorporated drug of 1.08 ± 0.01 mg/mL. Importantly, compared to free drug, AmB-PM protected AmB from degradation in an acidic (simulated gastric) environment. Viability studies in Caco-2 cells confirmed the safety/low toxicity of AmB-PM. In vitro cellular absorption studies confirmed that AmB-PM increased AmB uptake in Caco-2 cells 6-fold more than free AmB (i.e., 25% compared with 4% within 30 min). Furthermore, the permeability of AmB across Caco-2 monolayers was significantly faster (2-fold) and more pronounced for AmB-PM in comparison to free drug (3.5-fold increase). Thus, the developed AmB-PM show promise as a novel oral delivery system for AmB and justifies further investigation.

Prevalence and Factors Associated with Analgesic Prescribing in Poly-Medicated Elderly Patients.

BACKGROUND: Pain is common in older patients and management guidelines rarely consider the effect of multiple comorbidities and concurrent medications on analgesic selection. OBJECTIVES: The objectives of this study were to identify the prevalence and pattern of analgesic prescribing and associated factors in older patients with polypharmacy. METHODS: Older patients (aged ≥ 75 years) admitted to the Royal Adelaide Hospital between September 2015 and August 2016 and with polypharmacy were included and their comorbidities and medications prescribed at discharge were recorded. Drug Burden Index and Charlson Comorbidity Index were calculated. The number of medications that increased the risk of orthostatic hypotension were recorded. Logistic regression was used to compute the association between analgesic use and participant characteristics, and results were presented as odds ratios and 95% confidence intervals, adjusted for age, sex, Charlson Comorbidity Index, Drug Burden Index and orthostatic hypotension. RESULTS: Over 15,000 admissions were identified, of which 1192 patients were included, 824 (69%) of whom were prescribed an analgesic medication. Paracetamol (used by 89% of analgesic users), opioids (34%) and adjuvants (17%) were used more frequently than non-steroidal anti-inflammatory drugs (8%). Analgesic users had a higher Drug Burden Index, were prescribed more medications and were less likely to be male compared with non-users. Charlson Comorbidity Index across the cohort was high (7.3 ± 1.9) but there was no difference between analgesic users and non-users, but analgesic users were more likely to have a documented diagnosis of osteoarthritis, osteoporosis and falls. Opioid use was associated with the Drug Burden Index, while adjuvant use was associated with orthostatic hypotension. Opioid use was associated with having a diagnosis of osteoporosis and falls. CONCLUSIONS: In our cohort of poly-medicated elderly patients, prescription of analgesic medications was common, and these patients are likely to have an increased rate of adverse drug reactions and falls compared with those who were not prescribed analgesic medications.

Food, gastrointestinal pH, and models of oral drug absorption.

This article reviews the major physiological and physicochemical principles of the effect of food and gastrointestinal (GI) pH on the absorption and bioavailability of oral drugs, and the various absorption models that are used to describe/predict oral drug absorption. The rate and extent of oral drug absorption is determined by a complex interaction between a drug's physicochemical properties, GI physiologic factors, and the nature of the formulation administered. GI pH is an important factor that can markedly affect oral drug absorption and bioavailability as it may have significant influence on drug dissolution & solubility, drug release, drug stability, and intestinal permeability. Different regions of the GI tract have different drug absorptive properties. Thus, the transit time in each GI region and its variability between subjects may contribute to the variability in the rate and/or extent of drug absorption. Food-drug interactions can result in delayed, decreased, increased, and sometimes un-altered drug absorption. Food effects on oral absorption can be achieved by direct and indirect mechanisms. Various models have been proposed to describe oral absorption ranging from empirical models to the more sophisticated "mechanism-based" models. Through understanding of the physicochemical and physiological rate-limiting factors affecting oral absorption, modellers can implement simplified population-based modelling approaches that are less complex than whole-body physiologically-based models but still capture the essential elements in a physiological way and hence will be more suited for population modelling of large clinical data sets. It will also help formulation scientists to better predict formulation performance and to develop formulations that maximize oral bioavailability.

Glial Attenuation With Ibudilast in the Treatment of Medication Overuse Headache: A Double-Blind, Randomized, Placebo-Controlled Pilot Trial of Efficacy and Safety.

BACKGROUND: Medication overuse headache (MOH) is a condition bordering between a chronic pain condition and a substance dependence disorder. Activation of immunocompetent glial cells in the central nervous system has been linked to both pathological pain and drug addiction/reward. Preclinically, ibudilast attenuates glial activation and is able to reduce neuropathic pain and markers of substance dependence. We therefore hypothesized ibudilast would reduce headache burden and opioid analgesic requirements in patients with opioid overuse headache. OBJECTIVE: To determine if treatment with ibudilast provides a greater reduction in headache index than placebo in MOH patients consuming opioids. METHODS: Participants with MOH who were using opioids were randomized via computer-generated code to ibudilast 40 mg or placebo twice daily for 8 weeks in a double-blind, parallel groups study. Before randomization participants completed a 4-week baseline headache diary. During treatment, headache diary data collection continued and participants attended 4 study visits during which quantitative sensory testing was performed. Blood samples for immune biomarker analyses were collected before and after treatment in a subgroup of participants. RESULTS: Thirty-four participants were randomized, 13 of 15 randomized to ibudilast and 17 of 19 randomized to placebo completed treatment. Ibudilast was generally well-tolerated with mild, transient nausea reported as the most common adverse event (66.7% vs 10.5% in placebo group). Results are shown as mean (SD). At the end of treatment no differences in the primary outcome average daily headache index (placebo 62 [44] vs ibudilast 77 [72] groups, difference -15, CI -65 to 35 h × numerical rating scale), or secondary outcomes headache frequency (placebo 23 [8.1] vs ibudilast 24.5 [6.2], difference -1.5, CI -7.7 to 4.8 days/month) and opioid intake (placebo 20.6 [43] vs ibudilast 19 [24.3], difference 1.6, CI -31.5 to 34.8 mg morphine equivalent) were observed between placebo and ibudilast groups. CONCLUSIONS: Using the current dosing regimen, ibudilast does not improve headache or reduce opioid use in patients with MOH without mandated opioid withdrawal. However, it would be of interest to determine in future trials if ibudilast is able to improve ease of withdrawal during a forced opioid down-titration when incorporated into an MOH detoxification program.

Colorectal carcinogenesis: a cellular response to sustained risk environment.

The current models for colorectal cancer (CRC) are essentially linear in nature with a sequential progression from adenoma through to carcinoma. However, these views of CRC development do not explain the full body of published knowledge and tend to discount environmental influences. This paper proposes that CRC is a cellular response to prolonged exposure to cytotoxic agents (e.g., free ammonia) as key events within a sustained high-risk colonic luminal environment. This environment is low in substrate for the colonocytes (short chain fatty acids, SCFA) and consequently of higher pH with higher levels of free ammonia and decreased mucosal oxygen supply as a result of lower visceral blood flow. All of these lead to greater and prolonged exposure of the colonic epithelium to a cytotoxic agent with diminished aerobic energy availability. Normal colonocytes faced with this unfavourable environment can transform into CRC cells for survival through epigenetic reprogramming to express genes which increase mobility to allow migration and proliferation. Recent data with high protein diets confirm that genetic damage can be increased, consistent with greater CRC risk. However, this damage can be reversed by increasing SCFA supply by feeding fermentable fibre as resistant starch or arabinoxylan. High protein, low carbohydrate diets have been shown to alter the colonic environment with lower butyrate levels and apparently greater mucosal exposure to ammonia, consistent with our hypothesis. Evidence is drawn from in vivo and in vitro genomic and biochemical studies to frame experiments to test this proposition.

Medication-overuse headache and opioid-induced hyperalgesia: A review of mechanisms, a neuroimmune hypothesis and a novel approach to treatment.

INTRODUCTION: Patients with chronic headache who consume large amounts of analgesics are often encountered in clinical practice. Excessive intake of analgesics is now considered to be a cause, rather than simply a consequence, of frequent headaches, and as such the diagnosis "medication-overuse headache" (MOH) has been formulated. Despite the prevalence and clinical impact of MOH, the pathophysiology behind this disorder remains unclear and specific mechanism-based treatment options are lacking. DISCUSSION: Although most acute headache treatments have been alleged to cause MOH, here we conclude from the literature that opioids are a particularly problematic drug class consistently associated with worsening headache. MOH may not be a single entity, as each class of drug implicated may cause MOH via a different mechanism. Recent evidence indicates that chronic opioid administration may exacerbate pain in the long term by activating toll-like receptor-4 on glial cells, resulting in a pro-inflammatory state that manifests clinically as increased pain. Thus, from the available evidence it seems opioid-overuse headache is a phenomenon similar to opioid-induced hyperalgesia, which derives from a cumulative interaction between central sensitisation, due to repeated activation of nociceptive pathways by recurrent headaches, and pain facilitation due to glial activation. CONCLUSION: Treatment strategies directed at inhibiting glial activation may be of benefit alongside medication withdrawal in the management of MOH.

Identification of potential pathways involved in induction of apoptosis by butyrate and 4-benzoylbutyrate in HT29 colorectal cancer cells.

Butyrate and its analogues have long been investigated as potential chemotherapeutic agents. Our previous structure-activity relationship studies of butyrate analogues revealed that 4-benzoylbutyrate had comparable in vitro effects to butyrate when used to treat HT29 and HCT116 colorectal cancer cell lines. The aim of this study was to identify potential mechanisms associated with the antitumorigenic effects of 4-benzoylbutyrate. In this study, butyrate, 3-hydroxybutyrate and 4-benzoylbutyrate were also investigated for their effects on histone deacetylase (HDAC) activity and histone H4 acetylation in HT29 and HCT116 cells. The biological effects of these analogues on HT29 cells were further investigated using quantitative proteomics to determine the proteins potentially involved in their apoptotic and antiproliferative effects. Because 3-hydroxybutyrate had minimal to no effect on apoptosis, proliferation or HDAC activity, this analogue was used to identify differentially expressed proteins that were potentially specific to the apoptotic effects of butyrate and/or 4-benzoylbutyrate. Butyrate treatment inhibited HDAC activity and induced H4 acetylation. 4-Benzoylbutyrate inhibited HDAC activity but failed to enhance H4 acetylation. Proteomic analysis revealed 20 proteins whose levels were similarly altered by both butyrate and 4-benzoylbutyrate. Proteins that showed common patterns of differential regulation in the presence of either butyrate or 4-benzoylbutyrate included c-Myc transcriptional targets, proteins involved in ER homeostasis, signal transduction pathways and cell energy metabolism. Although an additional 23 proteins were altered by 4-benzoylbutyrate uniquely, further work is required to understand the mechanisms involved in its apoptotic effects.

The effects of pregabalin and the glial attenuator minocycline on the response to intradermal capsaicin in patients with unilateral sciatica.

BACKGROUND: Patients with unilateral sciatica have heightened responses to intradermal capsaicin compared to pain-free volunteers. No studies have investigated whether this pain model can screen for novel anti-neuropathic agents in patients with pre-existing neuropathic pain syndromes. AIM: This study compared the effects of pregabalin (300 mg) and the tetracycline antibiotic and glial attenuator minocycline (400 mg) on capsaicin-induced spontaneous pain, flare, allodynia and hyperalgesia in patients with unilateral sciatica on both their affected and unaffected leg. METHODS/RESULTS: Eighteen patients with unilateral sciatica completed this randomised, double-blind, placebo-controlled, three-way cross-over study. Participants received a 10 µg dose of capsaicin into the middle section of their calf on both their affected and unaffected leg, separated by an interval of 75 min. Capsaicin-induced spontaneous pain, flare, allodynia and hyperalgesia were recorded pre-injection and at 5, 20, 40, 60 and 90 min post-injection. Minocycline tended to reduce pre-capsaicin injection values of hyperalgesia in the affected leg by 28% (95% CI 0% to 56%). The area under the effect time curves for capsaicin-induced spontaneous pain, flare, allodynia and hyperalgesia were not affected by either treatment compared to placebo. Significant limb differences were observed for flare (AUC) (-38% in affected leg, 95% CI for difference -19% to -52%). Both hand dominance and sex were significant covariates of response to capsaicin. CONCLUSIONS: It cannot be concluded that minocycline is unsuitable for further evaluation as an anti-neuropathic pain drug as pregabalin, our positive control, failed to reduce capsaicin-induced neuropathic pain. However, the anti-hyperalgesic effect of minocycline observed pre-capsaicin injection is promising pilot information to support ongoing research into glial-mediated treatments for neuropathic pain. The differences in flare response between limbs may represent a useful biomarker to further investigate neuropathic pain. Inclusion of a positive control is imperative for the assessment of novel therapies for neuropathic pain.

Rosemary and cancer prevention: preclinical perspectives.

Colorectal cancer is the second leading cause of cancer death in Australia. Nutrition, particularly intake of vegetables and certain plant components, has been reported to have a major role in cancer risk reduction. Recently, there has been a growing research interest in rosemary, a common household plant grown in many parts of the world. This study aims to review scientific evidence from all studies, published from 1996 to March 2010 that examined the protective effects of rosemary on colorectal cancer and other types of cancer. Literature evidence from animal and cell culture studies demonstrates the anticancer potential of rosemary extract, carnosol, carnosic acid, ursolic acid, and rosmarinic acid. No evidence for other rosemary constituents was found. The reported anticancer properties were found to arise through the molecular changes in the multiple-stage process of cancer development, which are dose related and not tissue or species specific. This is evidenced by the ability of rosemary to suppress the development of tumors in several organs including the colon, breast, liver, stomach, as well as melanoma and leukemia cells. The results suggested that the different molecular targets modulated by rosemary and its active constituents are useful indicators of success in clinical cancer chemo-prevention trials.