Modulation of dendritic release of dopamine by metabotropic glutamate receptors in rat substantia nigra

A superfusion system was used to study the effects of metabotropic glutamate receptor (mGluR) ligands upon the release of [(3)H]dopamine ([(3)H]DA) previously taken up by rat substantia nigra (SN) slices. trans-(+/-)-1-Amino-(1S,3R)-cyclopentane dicarboxylic acid (trans-ACPD; 100 and 600 microM), a group I and II mGluR agonist, evoked the release of [(3)H]DA from nigral slices. This last effect was reduced significantly by (2S,3S,4S)-2-methyl-2-(carboxycyclopropyl)-glycine (MCCG; 300 microM), an antagonist of group II mGluR, or by the addition of tetrodotoxin (D-APV; 1 microM) to the superfusion medium. D-(-)-2-Amino-5-phosphono-valeric acid (100 microM), an N-methyl-D-aspartate receptor antagonist, or the presence of Mg(2+) (1.2mM) in the superfusion medium did not modify trans-ACPD-induced [(3)H]DA release. In addition, a group II mGluR agonist such as (2S,1'R,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)-glycine (DCG-IV; 100 microM) significantly induced the release of [(3)H]DA from nigral slices, whereas a group I mGluR agonist such as (RS)-3,5-dihydroxyphenylglycine (DHPG; 50 and 100 microM) did not modify the release of the [(3)H]-amine. Further experiments showed that the NMDA (100 microM)-evoked release of [(3)H]DA was decreased significantly by prior exposure of SN slices to trans-ACPD. Finally, partial denervation of the DA nigro-striatal pathway with 6-hydroxydopamine (6-OH-DA) increased trans-ACPD-induced release of [(3)H]DA, whereas it decreased trans-ACPD inhibitory effects on NMDA-evoked release of [(3)H]DA from nigral slices. The present results suggest that the dendritic release of DA in the SN is regulated by mGluR activation. Such nigral mGluR activation may produce opposite effects upon basal and NMDA-evoked release of DA in the SN. In addition, such mGluR-induced effects in the SN are modified in response to partial denervation of the DA nigro-striatal pathway.     

Long-term antidepressant treatment

Major depressive disorder (MDD) is a common and costly illness. Recent research suggests that MDD is a lifelong condition for many patients. This has stimulated researchers to identify risk factors associated with an increased frequency of relapse and recurrence of major depression. One of the most important of these risk factors is an incomplete response to acute treatment. These data have led investigators to pursue techniques that enhance the acute response of patients to therapy, and study whether long-term treatment with antidepressants may prevent relapse and recurrence of MDD. Data from these trials suggest that continuation and maintenance treatment of MDD confers some protection against deteriorating back into an episode after acute treatment and against developing another episode of MDD.     

Biological activity of for-Met-Leu-Phe-OMe analogs: relevant substitutions specifically trigger killing mechanisms in human neutrophils

Two analogs of the prototypical peptide for-Met-Leu-Phe-OMe (fMLP-OMe), for-Gln-Tyr-Phe-OMe (1) and for-Gln-Tyr-Tyr-OMe (2), carrying unusual hydrophilic residues, were synthesized in order to investigate whether they provoked specific biological responses, as well as intracellular calcium mobilization, in human neutrophils. Whereas neither compound stimulates chemotaxis, both are able to elicit lysosomal enzyme production. However compound 1 is able to trigger copious superoxide anion production while compound 2 only elicits minor superoxide anion production. In binding experiments on formylpeptide receptors, the newly synthesized compounds for-Gln-Tyr-Phe-OMe (1) and for-Gln-Tyr-Tyr-OMe (2) showed affinity values in the micromolar range. These derivatives demonstrate inability to find a positive contribute from single substitutions. A very important result of this research is the evidence of the ability of the formyl group alone to trigger the primary target of the human neutrophil activity, i.e. killing mechanisms, by activating the specific receptor conformation.     

Synthesis and Biological Evaluation of 2-Amino-3-(4-chlorobenzoyl)-4-[(4-arylpiperazin-1-yl)methyl]-5-substituted-thiophenes. Effect of the 5-Modification on Allosteric Enhancer Activity at the A(1) Adenosine Receptor

We have recently reported a detailed structure-activity relationship study around a wide series of 2-amino-3-(4-chlorobenzoyl)-4-[(4-arylpiperazin-1-yl)methyl]thiophene derivatives as potent allosteric enhancers of the A(1) adenosine receptor. In the current study, we have continued to explore the potential of these molecules by synthesizing of a novel series of analogues that share a common 2-amino-3-(4-chlorobenzoyl)thiophene nucleus. Modifications were focused on varying the nature and the position of electron-withdrawing or electron-releasing groups on the phenyl of an arylpiperazine moiety attached at the 4-position of the thiophene ring by a methylene chain, combined with the presence of small alkyl groups (methyl or ethyl), bromine, or aryl moieties at the thiophene C-5 position. In this series of compounds, substitution at the 5-position had a fundamental effect on activity, with the 5-aryl group contributing additively to the allosteric enhancer activity. The thiophene C-5 aryl derivatives 4ad, 4ak, and 4al were the most active compounds in binding and functional experiments.     

In vitro Cytotoxicity of Extracts from Brazilian Asteraceae

Aqueous and organic extracts of Asteraceae (Compositae) collected from the State of Rio Grande do Sul, Brazil, have been tested in vitro for cytotoxic activity against human solid tumour cell lines. Twenty-five species, 125 extracts in total, were screened against HT29 human colon adenocarcinoma cells and NCI-H460 human non-small cell lung cancer cells. Twenty-five extracts from 11 species demonstrated cytotoxicity at 100µg/ml against one or both of the cell lines tested. Further analysis was performed on the active extracts using three cell lines HT29, NCI-H460, and U373 human glioblastoma cells, to determine the IC 50 and the degree of tumour cell line selectivity. Extracts from Baccharis coridifolia, Baccharis ochracea, Eupatorium macrocephalum, Eupatorium pedunculosum and Stenachaenium riedelii all produced IC 50 values below 5µg/ml. Comparison of the IC 50 results between cell lines identified that Baccharis coridifolia, Baccharis ochracea, Eupatorium laevigatum and Pluchea sagittalis extracts produced differential sensitivity across the panel of three cell lines. These species are currently under further investigation with the ultimate objective of isolation and identification of the active principles responsible for the anti-proliferative activity.     

Cannabinoid CB(2) receptors modulate ERK-1/2 kinase signalling and NO release in microglial cells stimulated with bacterial lipopolysaccharide

BACKGROUND AND PURPOSE

Cannabinoid (CB) receptor agonists have potential utility as anti-inflammatory drugs in chronic immune inflammatory diseases. In the present study, we characterized the signal transduction pathways affected by CB₂ receptors in quiescent and lipopolysaccharide (LPS)-stimulated murine microglia.

EXPERIMENTAL APPROACH

We examined the effects of the synthetic CB₂ receptor ligand, JWH-015, on phosphorylation of MAPKs and NO production.

KEY RESULTS

Stimulation of CB₂ receptors by JWH-015 activated JNK-1/2 and ERK-1/2 in quiescent murine microglial cells. Furthermore, CB₂ receptor activation increased p-ERK-1/2 at 15 min in LPS-stimulated microglia. Surprisingly, this was reduced after 30 min in the presence of both LPS and JWH-015. The NOS inhibitor l-NAME blocked the ability of JWH-015 to down-regulate the LPS-induced p-ERK increase, indicating that activation of CB₂ receptors reduced effects of LPS on ERK-1/2 phosphorylation through NO. JWH-015 increased LPS-induced NO release at 30 min, while at 4 h CB₂ receptor stimulation had an inhibitory effect. All the effects of JWH-015 were significantly blocked by the CB₂ receptor antagonist AM 630 and, as the inhibition of CB₂ receptor expression by siRNA abolished the effects of JWH-015, were shown to be mediated specifically by activation of CB₂ receptors.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrate that CB₂ receptor stimulation activated the MAPK pathway, but the presence of a second stimulus blocked MAPK signal transduction, inhibiting pro-inflammatory LPS-induced production of NO. Therefore, CB₂ receptor agonists may promote anti-inflammatory therapeutic responses in activated microglia.     

Impact of Comorbidities on Hospital-Acquired Infections in a Geriatric Rehabilitation Unit: Prospective Study of 252 Patients

ObjectivesHospital-acquired infections (HAIs) remain a major source of morbidity and mortality in long-term care units, despite advances in antimicrobial therapy and preventive measures. Our aim was to investigate risk factors for HAIs, especially in the elderly, and to describe the relationship between comorbidities (number, severity, and specific diseases) and HAIs using a comprehensive inventory of comorbidities.DesignProspective cohort studySettingGeriatric rehabilitation unit in a university hospital in the Paris metropolitan area.ParticipantsParticipants were 252 consecutive patients aged 75 years or older (mean age, 85 ± 6.2 years) and admitted between 2006 and 2008.MeasurementsSurveillance of HAI was conducted. A complete inventory of comorbidities was done using the Cumulative Illness Rating Scale for Geriatrics (CIRS-G). Potential risk factors were evaluated in 2 risk models, one with HAI acquisition, CIRS-G, activities of daily living score less than 10, and at least 1 invasive procedure (yes/no) and the other with HAI acquisition and specific invasive procedures and diseases.ResultsOf the 252 patients, 97 experienced HAIs, for an incidence of 5.6 infections per 1000 bed-days. The most common HAI sites were the respiratory tract (48%; 65/136) and urinary tract (37%; 51/136). The CIRS-G global score and comorbidity index were higher in patients with than without HAIs. Among HAI categories, respiratory and urogenital diseases were more prevalent in the group with HAIs. In the model combining CIRS-G, activities of daily living score less than 10, and at least 1 invasive procedure, independent risk factors for HAI were CIRS-G index (odds ratio [OR], 1.55; 95% confidence interval [95% CI], 1.13–2.11; P = .005) and invasive procedures (OR, 5.18; 95% CI, 2.77–9.71; P < .001). In the model including specific procedures and diseases, independent risk factors for HAI were intravenous catheter (OR, 7.39; 95% CI, 2.94–18.56; P < .001), urinary catheter (OR, 3.33; 95% CI, 1.40–7.88; P = .006), gastrointestinal endoscopy (OR, 3.69; 95% CI, 1.12–12.16; P = .03), pressure sores (OR, 2.52; 95% CI, 1.04–6.10; P = .03), and swallowing impairment (OR, 3.37; 95% CI, 1.16–9.74; P = .02).ConclusionsThis study identified several important risk factors for HAIs. There is a need for HAI prevention via the implementation of infection-control programs, including surveillance, in rehabilitation units.     

Hydroxytyrosol excretion differs between rats and humans and depends on the vehicle of administration

Interest in the in vivo biological activities of olive oil phenolics is rapidly growing, and different models and vehicles of administration are used worldwide. Matters of practicality determine the use of rats rather than humans as the model of choice. Also, growing interest in nutraceuticals is leading to the formulation of compounds containing olive oil phenols. In this study, we compared metabolism and urinary excretion of hydroxytyrosol [(HT), the most representative phenol of olive oil] between rats and humans by evaluating excretion of HT and its major metabolite, homovanillyl alcohol. Also, we compared human excretion of HT when consumed as a natural component of extra virgin olive oil, when added to refined olive oil, or when added to yogurt (as an approximation of functional food). Urinary excretion of HT was greater in humans than in rats, a species with a high basal excretion of HT and its metabolites. The high (234% of HT administered) excretion of free HT suggests that hydrolysis of oleuropein administered in humans (still an unresolved issue) occurs in vivo. Moreover, human HT excretion was much higher after its administration as a natural component of olive oil (44.2% of HT administered) than after its addition to refined olive oil (23% of HT administered) or yogurt (5.8% of dose or approximately 13% of that recorded after virgin olive oil intake). These data suggest that the rat is not the appropriate model for the study of HT metabolism and that HT-containing functional foods should be carefully formulated.     

Social inequalities in health‐related use of time in Australian adolescents

Objective: Young people's socioeconomic position and time use behaviours – including physical activity, sedentary behaviours, social engagement, sleep and cognitive activities – have been associated with health outcomes. This study aimed to describe how time use varies with household income in a representative sample of 9–16 year old Australians. Methods: A random sample of 2,071 9–16 year old Australian children provided household income data and four days’ use‐of‐time data. Average daily minutes spent in various types of activities were calculated. Kruskal‐Wallis and Mann Whitney U tests were used to compare time use across the income bands. Results: Higher income participants spent significantly more time playing sport (p<0.0001), including team sports (p=0.0005), and in cognitively demanding behaviours such as school routine (p<0.0001), doing homework (p<0.0001) and playing music (p=0.001) than their low‐income counterparts. Conversely, low‐income participants spent significantly more time watching television (p<0.001) and playing videogames (p<0.0002). There were no differences in sleep or social interaction. Screen time and school‐related activities were the major locations of differences. Conclusions: Time use differences in the areas of sport, school‐related and screen activities may be associated with various health and wellbeing outcomes, and thus be a source of health inequalities. Implications : Socioeconomic‐related time use behaviour differences could be used to develop specific interventions to address health inequalities via interventions addressing time use or income inequalities.