Simultaneous blockade of adenosine A2A and metabotropic glutamate mGlu5 receptors increase their efficacy in reversing Parkinsonian deficits in rats.

Recent evidence suggest that antagonism of adenosine A2A receptors represent an alternative therapeutic approach to Parkinson's disease (PD). Coactivation of A2A and the glutamate subtype 5 metabotropic receptors (mGlu5) synergistically stimulates DARPP-32 phosphorylation and c-fos expression in the striatum. This study therefore tested the effects of a joint blockade of these receptors to alleviate the motor dysfunction in a rat model of PD. 6-Hydroxydopamine infusions in the striatum produced akinetic deficits in rats trained to release a lever after a stimulus in a reaction time (RT) task. At 2 weeks after the lesion, A2A and mGlu5 receptors selective antagonists 8-(3-chlorostyryl)caffeine (CSC) and 2-methyl-6-(phenylethynyl)-pyridine (MPEP) were administered daily for 3 weeks either as a single or joint treatment. Injections of CSC (1.25 mg/kg) and MPEP (1.5 mg/kg) separately or in combination reduced the increase of delayed responses and RTs induced by 6-OHDA lesions, while the same treatment had no effect in controls. Furthermore, coadministration of lower doses of 0.625 mg/kg CSC and 0.375 mg/kg MPEP noneffective as a single treatment promoted a full and immediate recovery of akinesia, which was found to be more efficient than the separate blockade of these receptors. These results demonstrate that the combined inactivation of A2A and mGlu5 receptor potentiate their beneficial effects supporting this pharmacological strategy as a promising anti-Parkinsonian therapy.     

Estimation of particle number by stereology: an update.

Sampling designs dictated by stereology have proven very useful in recent years to estimate in situ the total number of deposited particles, or of macrophages, in different lung compartments at the light microscopical level. The sampling methods are based on parallel slabs which are subsequently subsampled by disectors. The resulting number estimators are unbiased irrespective of tissue shrinkage or swelling, and they are readily applicable in other contexts (notably in neuroscience). Several variants of the design are available, however, and, although they all yield the same number estimates, their precision, and the mathematical prediction of it, vary among the different estimators and are subjected to theoretical improvement. The present paper constitutes a detailed survey of the latest advances, and it illustrates methods and formulae alike by way of a real example stemming from an earlier study on particle retention and clearance.     

Drop‐offs in the isoniazid preventive therapy cascade among children living with HIV in western Kenya, 2015–2019

IntroductionIsoniazid preventive therapy (IPT) can reduce the risk of tuberculosis (TB) in children living with HIV (CLHIV), but data on the outcomes of the IPT cascade in CLHIV are limited.MethodsWe evaluated the IPT cascade among CLHIV aged <15 years and newly enrolled in HIV care in eight HIV clinics in western Kenya. Medical record data were abstracted from September 2015 through July 2019. We assessed the proportion of CLHIV completing TB symptom screening, IPT eligibility assessment, IPT initiation and completion. TB incidence rate was calculated stratified by IPT initiation and completion status. Risk factors for IPT non‐initiation and non‐completion were assessed using Poisson regression with generalized linear models.ResultsOverall, 856 CLHIV were newly enrolled in HIV care, of whom 98% ([95% CI 97–99]; n = 841) underwent screening for TB symptoms and IPT eligibility. Of these, 13 (2%; 95% CI 1–3) were ineligible due to active TB and 828 (98%; 95% CI 97–99) were eligible. Five hundred and fifty‐nine (68%; 95% CI 64–71) of eligible CLHIV initiated IPT; median time to IPT initiation was 3.6 months (interquartile range [IQR] 0.5–10.2). Overall, 434 (78%; 95% CI 74–81) IPT initiators completed. Attending high‐volume HIV clinics (aRR = 2.82; 95% CI 1.20–6.62) was independently associated with IPT non‐initiation. IPT non‐initiation had a trend of being higher among those enrolled in the period 2017–2019 versus 2015–2016 (aRR = 1.91; 0.98–3.73) and those who were HIV virally non‐suppressed (aRR = 1.90; 95% CI 0.98–3.71). Being enrolled in 2017–2019 versus 2015–2016 (aRR = 1.40; 1.01–1.96) was independently associated with IPT non‐completion. By 24 months after IPT screening, TB incidence was four‐fold higher among eligible CLHIV who never initiated (8.1 per 1000 person years [PY]) compared to CLHIV who completed IPT (2.1 per 1000 PY; rate ratio [RR] = 3.85; 95% CI 1.08–17.15), with a similar trend among CLHIV who initiated but did not complete IPT (8.2/1000 PY; RR = 4.39; 95% CI 0.82–23.56).ConclusionsDespite high screening for eligibility, timely IPT initiation and completion were suboptimal among eligible CLHIV in this programmatic cohort. Targeted programmatic interventions are needed to address these drop‐offs from the IPT cascade by ensuring timely IPT initiation after ruling out active TB and enhancing completion of the 6‐month course to reduce TB in CLHIV.     

Two new lactones with mosquito larvicidal activity from three Hortonia species

The structures of the butenolides 1 and 2, isolated from the endemic plants Hortonia floribunda, H. angustifolia, and H. ovalifolia, collected in Sri Lanka, have been elucidated by spectroscopic analysis. These compounds exhibited potent mosquito larvicidal activity against the second instar larvae of Aedes aegypti.     

Adrenergic-cholinergic interactions in left atria: a study using K+ channel agonists, antagonist and pertussis toxin.

1. The role of activation of potassium conductance in the antagonism by the muscarinic agonist carbachol of positive inotropic responses to alpha- and beta-adrenoceptor stimulation was studied in electrically driven left atrial strips of the rabbit. 2. The potassium channel antagonist, 4-aminopyridine, attenuated the direct negative inotropic response to carbachol and the reversal by carbachol of positive inotropic responses to the alpha-adrenoceptor agonist phenylephrine (in the presence of timolol). The inhibitory effect of carbachol on positive inotropic responses to the beta-adrenoceptor agonist isoprenaline was much less affected by 4-aminopyridine. 3. Pretreatment of rabbits with pertussis toxin also attenuated the direct negative inotropic response to carbachol and the inhibitory effect of carbachol on positive inotropic responses to phenylephrine. 4. Neither carbachol nor phenylephrine, alone or in combination, had any effect on left atrial adenosine 3':5'-cyclic monophosphate (cyclic AMP) levels. 5. The potassium channel agonist, pinacidil, exerted a dose-dependent negative inotropic response in rabbit left atria and reversed positive inotropic responses to phenylephrine and isoprenaline. In the dose-range tested, pinacidil had a greater inhibitory effect on positive inotropic responses to phenylephrine than on positive inotropic responses to isoprenaline. 6. Pretreatment of left atria with pinacidil or cromakalim, another potassium channel agonist, antagonized positive inotropic responses to phenylephrine but not to isoprenaline. 7. These results suggest that activation of potassium conductance plays an important role in the inhibition by carbachol of positive inotropic responses of rabbit left atria to phenylephrine but not to isoprenaline.     

Effects of rhein on human articular chondrocytes in alginate beads

This study was designed to investigate the effects of rhein, the active metabolite of diacerhein, on the metabolic functions of human chondrocytes cultured in alginate beads.Enzymatically isolated osteoarthritic (OA) chondrocytes were cultured in alginate beads in a well-defined culture medium for 12 days. Rhein was tested in a range of concentrations comprised between 10(-7) and 4 x 10(-5)M, in the presence or absence of 10(-10)M IL-1beta. Interleukin (IL)-6 and -8, macrophage inflammatory protein (MIP-1beta), stromelysin-1 (MMP-3), aggrecan (AGG), tissue inhibitor of metalloproteinases-1 (TIMP-1), prostaglandin E(2) (PGE(2)) and nitric oxide (NO) productions were assayed. Cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS) mRNA steady-state levels were also quantified. In the basal condition, 10(-5)M rhein increased by 46.5% the production of AGG, decreased by 17-30% the production of IL-6, MMP-3, NO and MIP-1beta but enhanced by 50% the production of PGE(2). IL-1beta increased IL-6, IL-8, MIP-1beta, NO, PGE(2) and MMP-3 productions, but inhibited AGG and TIMP-1 synthesis. Rhein partially reversed the effect of IL-1beta on TIMP-1 and NO production, had no effect on AGG, IL-6 and MIP-1beta production, but up-regulated the IL-1beta stimulated PGE(2) production. The COX-2 and iNOS mRNA levels and IL-8 production were not modified by rhein.Overall, these results contribute to explain the clinical efficiency of rhein and give new information on its mechanisms of action.