Diverse signalling by different chemokines through the chemokine receptor CCR5

We have investigated the signalling properties of the chemokine receptor, CCR5, using several assays for agonism: stimulation of changes in intracellular Ca(2+) or CCR5 internalisation in CHO cells expressing CCR5 or stimulation of [(35)S]GTPgammaS binding in membranes of CHO cells expressing CCR5. Four isoforms of the chemokine CCL3 with different amino termini (CCL3, CCL3(2-70), CCL3(5-70), CCL3L1) were tested in these assays in order to probe structure/activity relationships. Each isoform exhibited agonism. The pattern of agonism (potency, maximal effect) was different in the three assays, although the rank order was the same with CCL3L1 being the most potent and efficacious. The data show that the amino terminus of the chemokine is important for signalling. A proline at position 2 (CCL3L1) provides for high potency and efficacy but the isoform with a serine at position 2 (CCL3(2-70)) is as efficacious in some assays showing that the proline is not the only determinant of high efficacy. We also increased the sensitivity of CCR5 signalling by treating cells with sodium butyrate, thus increasing the receptor/G protein ratio. This allowed the detection of a change in intracellular Ca(2+) after treatment with CCL7 and Met-RANTES showing that these ligands possess measurable but low efficacy. This study therefore shows that sodium butyrate treatment increases the sensitivity of signalling assays and enables the detection of efficacy in ligands previously considered as antagonists. The use of different assay systems, therefore, provides different estimates of efficacy for some ligands at this receptor.     

Protective effects of Swertia longifolia Boiss. and its active compound, swerchirin, on paracetamol-induced hepatotoxicity in mice

Aerial parts of Swertia longifolia Boiss. (Gentianaceae), which grows in the north of Iran, were screened for hepatoprotective activity against paracetamol (acetaminophen)-induced hepatotoxicity in Swiss mice. Pretreatment with total plant extract and swerchirin, the major component of the plant, significantly reduced the elevation of biochemical parameters, AST (aspartate aminotransferase), ALT (alanine aminotransferase) and ALP (alkaline phosphatase), the enzymes that are increased by liver damage (P < 0.001). Our results indicated that total plant extract and swerchirin were hepatoprotective in the range of 6-50 mg kg(-1) orally.     

Chromium-picolinate induced ocular changes: Protective role of ascorbic acid

Chromium-picolinate (Cr-picolinate) is a popular nutritional supplement; however its safety has been questioned with regard to its ability to act as a clastogen. The aim of the present work was to evaluate the biochemical, histological and morphological changes in the cornea and lens following oral administration of Cr-picolinate and the possible protective effect of Vitamin C. Ninety male Sprague-Dawley rats were divided into five groups included the control group, the groups treated with Cr-picolinate (0.8 and 1.5 mg/100 g b.w.) alone or in combination with Vitamin C (0.5 mg/100 g b.w.) for 8 weeks. The results indicated that the high dose of Cr-picolinate induced a significant decrease in SOD, GSH, Na(+)-, K(+)-ATPase levels, and a significant increase in MDA level. Severe morphological and histological changes in the cornea and lens accompanied with a decrease in the total soluble protein of the lens homogenate and changes in the crystalline fractions in lens. Vitamin C supplementation succeeded to restore these changes to great extent. It could be concluded that consumption of Cr-picolinate for a long time induced several hazards to cornea and lens. Supplementation with extra amounts of Vitamin C may be useful to restrain the Cr-picolinate induced ocular changes.     

Implication of inclusion complexation of glimepiride in cyclodextrin-polymer systems on its dissolution, stability and therapeutic efficacy

The effect of complexation of glimepiride, a poorly water-soluble antidiabetic drug, with β-cyclodextrin and its derivatives (HP-β-CyD and SBE-β-CyD) in presence of different concentrations of water-soluble polymers (HPMC, PVP, PEG 4000 and PEG 6000) on the dissolution rate of the drug has been investigated. The results revealed that the dissolution rate of the drug from these ternary systems is highly dependent on polymer type and concentration. The dissolution rate of the drug from ternary systems containing PEG 4000 or PEG 6000 seems to be generally higher than from systems containing HPMC or PVP. An optimum increase in the dissolution rate of the drug was observed at a polymer concentration of 5% for PEG 4000 or PEG 6000 and at 20% concentration of HPMC or PVP. The dissolution rate of the drug from the ternary system glimepiride–HP-β-CyD–5% PEG 4000 was high compared to the other systems. Tablets containing the drug or its equivalent amount of this ternary system were prepared and subjected to accelerated stability testing at 40 °C/75% R.H. to investigate the effect of storage on the chemical stability as well as therapeutic efficacy of the tablets. The results revealed stability of the tablets and consistent therapeutic efficacy on storage.     

Formulation and biological evaluation of glimepiride-cyclodextrin-polymer systems

Glimepiride is one of the third generation sulfonylureas used for treatment of type 2 diabetes. Poor aqueous solubility and slow dissolution rate of the drug lead to irreproducible clinical response or therapeutic failure in some cases due to subtherapeutic plasma drug levels. Consequently, the rationale of this study was to improve the biological performance of this drug through enhancing its solubility and dissolution rate. Inclusion complexes of glimepiride in beta-cyclodextrin (beta-CyD), hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) and sulfobutylether-beta-cyclodextrin (SBE-beta-CyD), with or without water soluble polymers were prepared by the kneading method. Binary systems were characterized by thermogravimetric analysis, IR spectroscopy and X-ray diffractometry. Phase solubility diagrams revealed increase in solubility of the drug upon cyclodextrin addition, showing A(p) type plot indicating high order complexation. All the ternary systems containing beta-CyD or HP-beta-CyD showed higher dissolution efficiency compared to the corresponding binary systems. The hypoglycemic effect of the most rapidly dissolving ternary system of glimepiride-HP-beta-CyD-PEG 4000 was evaluated after oral administration in diabetic rats by measuring blood glucose levels. The results indicated that this ternary system improves significantly the therapeutic efficacy of the drug. In conclusion, the association of water soluble polymers with glimepiride-CyD systems leads to great enhancement in dissolution rate, increased duration of action and improvement of therapeutic efficacy of the drug.     

Estimating time of last oral ingestion of cannabis from plasma THC and THCCOOH concentrations

Estimating the time of last cannabis use is important in assessing possible impairment of drivers involved in accidents, in verifying accuracy of court testimony and in the future, helpful in therapeutic monitoring of cannabis agonists. In 1992, Huestis et al developed model 1, based on plasma Delta-tetrahydrocannabinol (THC) concentrations, and model 2, on plasma 11-nor-9-carboxy-Delta(9)-tetrahydrocannbinol/THC ratios, that predicted 95% confidence intervals for time of last cannabis use. These models seemed to be valuable when applied to the small amount of data from published studies of oral ingestion, a route of administration more popular with the advent of cannabis therapies. A study was designed to further validate the models after oral ingestion of THC, and to determine whether they could predict last usage after multiple oral doses. Eighteen subjects in IRB-approved studies participated after providing informed consent. Each of 12 subjects in one group received a single 10 mg oral dose of dronabinol (synthetic THC). In another protocol, 6 subjects received 4 different oral daily doses, divided into thirds and administered with meals for 5 consecutive days. There was a 10-day washout period between each dosing regimen. Daily doses were 0.39, 0.47, and 14.8 mg THC in hemp oil and 7.5 mg dronabinol. Blood specimens were collected throughout the study and analyzed for plasma THC and 11-nor-9-carboxy-Delta(9)-tetrahydrocannbinol by gas chromatography/mass spectrometry with limits of quantification (LOQs) of 0.5 and 1.0 ng/mL, respectively. Actual times between ingestion of THC and blood collection spanned 0.5 to 16 hours. All plasma specimens with analyte concentrations >LOQ (n=90) were evaluated. Models 1 and 2 correctly predicted time of last THC ingestion for 74.4% and 90.0% of plasma specimens, respectively. 96.7% of predicted times were correct with one overestimate and 2 underestimates using the time interval defined by the lowest and highest 95% confidence limit of both models. These results provide further evidence of the usefulness of the predictive models in estimating the time of last oral THC ingestion after single or multiple doses.     

New strategies in evaluation of therapeutic efficacy in fibromyalgia syndrome

Fibromyalgia (FM) is continuing to be a challenging and confusing disorder for researchers and clinicians with its diverse symptoms, poorly understood etiology and pathophysiology. The use of multiple outcome variables reflecting the complexity of FM and co-morbid syndromes, makes it difficult to evaluate the efficacy or effectiveness of the treatment in clinical trials. Additionally researchers inevitably rely on patients' self-reported outcome data, which is prone to error and bias. In this paper, new researches in the field of FM and practical issues on methodology of pain assessment (visual analogue scales, paper or electronic diaries and compliance), core outcome domains in chronic pain assessment (IMMPACT recommendations), and advances in neuroimaging techniques like functional magnetic resonance imaging have been reviewed. Consequently, clinicians and researchers have various highly validated and adequate outcome domains to assess FM symptoms and new researches continue to add new valuable domains. Nevertheless the current problem is to conclude, which treatment works best for whom and which are the outcome domains suitable for FM patients or patients' subgroups with different prominent features. Standardised and appropriate core outcome domains for FM clinical trails will encourage more complete investigations, relevant outcome reporting and well-designed multicenter trials.