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Te appropriate diets 100mg silagra visa impotence in men symptoms and average age, behaviour change and exer- Indian Polycap study reduced systolic blood cise generic 100 mg silagra with visa does erectile dysfunction cause low libido. Research is needed to measure both the pressure by 7. Tese reductions were better or similar Main conclusions to those of single drugs or combinations of single ■ Early research shows that the Polycap for- drugs and tolerability was similar to that of other mulation, a single pill that combines several treatments. Efects of the polypill at the wider drugs, might be a simple and practical way population level might be afected by adherence. Comorbidity ofers the potential to evaluate more precisely the efcacy of for targeted treatment, if and when a polypill is the polypill, and for operational research used for primary prevention. Te drug is thus of reducing the risk of cardiovascular difcult to administer and constitutes a burden disease, such as dietary changes, the pre- both for the patient and for the health system. The efficacy of an alternative drug, paro- momycin sulfate (PM), has been demonstrated Case-study 7 in India (49). There is, however, limited infor- mation on the efficacy of PM for VL in the Combination treatment with African setting where response to treatment sodium stibogluconate (SSG) may be different. A large observational study of 4263 VL patients in South Sudan showed and paromomycin compared to that a combination of SSG and PM for a shorter SSG monotherapy for visceral period of time (17 days) yielded better results leishmaniasis: a randomized than SSG alone (50). For registration of PM and evaluation of the efficacy of combination treat- controlled trial in Ethiopia, ment with SSG and PM in East Africa, efficacy Kenya, Sudan and Uganda and safety data were required from a phase III randomized controlled trial. The need for research Human visceral leishmaniasis (VL), also known Study design as kala-azar, is a life-threatening parasitic dis- A multicentre randomized controlled trial ease caused by Leishmania donovani and trans- was conducted in four East African countries mitted by phlebotomine sandfies (Fig. Te VL is the second largest parasitic killer in the trial had three arms: (i) SSG monotherapy (a world afer malaria, with an annual worldwide dose of 20 mg/kg/day for 30 days) used as the incidence of approximately 500 000 cases (47). In East Africa, the SSG and PM given for a shorter period (SSG 20 incidence rate is 30 000 cases with 4000 deaths mg/kg/day; PM 15 mg/kg/day for 17 days). Te Leishmania parasite migrates aim was to compare the efcacy and safety of to internal organs such as the liver, spleen and PM monotherapy and the combination of SSG bone marrow (hence the term “visceral”) and, if and PM to the reference arm of SSG alone. Efective primary efcacy end point was defnitive cure measures to eradicate the sandfy are lacking, defned as parasite clearance from splenic, bone death rates are high, and there are few afordable marrow or lymph node aspirates six months and efective treatment options. In the comparison between PM monotherapy Treatment for VL in East Africa is primarily and SSG alone, 205 patients were enrolled in each limited to the antimonial sodium stibogluco- arm with primary efcacy data available for 198 nate (SSG), which is efcacious but requires four and 200 patients respectively. In the comparison weeks of hospitalization and daily intramuscular between the SSG/PM combination and the SSG 73 Research for universal health coverage Fig. Clinical examination of a 4-year-old girl with visceral leishmaniasis (kala-azar), in Sudan reference, 381 and 386 patients were enrolled in lowered the associated costs. Te cost of the each arm respectively with efcacy data available drugs also favoured the combination treatment for 359 patients per arm. Te efcacy of PM monotherapy was sig- Te potential risk of parasite resistance to SSG nifcantly lower than the efcacy observed in was also limited by combination therapy. Te efcacy SSG/PM combination therapy for treatment of of the SSG/PM combination given for a shorter VL in East Africa. A WHO Expert Committee duration of 17 days was similar to the efcacy of recommended its use as a frst-line treatment for SSG given alone for 30 days (91. Tere were no apparent diferences in the safety profle of Main conclusions the three treatment regimens. An observational multicountry study was con- ■ Te fndings supported the introduction of ducted in primary government health facilities SSG and PM combination therapy as a frst- in Bangladesh, Brazil, Uganda and the United line treatment for VL in East Africa. Te clinical perfor- mance of health workers with a longer duration of pre-service training (such as doctors and clin- Case-study 8 ical ofcers) was compared with those having a shorter duration of training (all other health Task shifting in the scale-up workers such as nurses, midwives and nurse of interventions to improve assistants providing clinical care). Te quality of care was evaluated using standardized indica- child survival: an observational tors and according to whether the assessment, multicountry study in Bangladesh, classifcation and management of sick children Brazil, Uganda and the United by IMCI guidelines had been fully carried out. Every child was assessed twice, frst by the IMCI- Republic of Tanzania trained health worker who was being assessed and second by a supervisor who was blinded to The need for research the original diagnosis and treatment made by WHO estimates that the global health workforce the health worker. Although this research has has a defcit of more than four million persons been classifed as a study of the management of (51). Countries with high child mortality rates diseases and conditions, it is also health policy also tend to have a lack of qualifed health work- and systems research.
The theory and practice of 3D vidual genes in mice by means of in vitro experimental tech- PET silagra 50mg for sale erectile dysfunction qof. Recently developed animal-dedicated PET devices tion of microPET: a high-resolution lutetium oxyorthosilicate (e order 100 mg silagra with visa erectile dysfunction medication ratings. J Nucl Med 1999;40: of about 2 mm and can now image these animalsin vivo 1164–1175. Performance results of a SPECT measurements of amphetamine-induced dopamine re- new DOI detector block for a high resolution PET–LSO research lease in nonhuman primates. Relationship of octanol/water partition coefficient and lated dopamine release competes in vivo for [123I]IBZM binding molecular weight to rat brain capillary permeability. Kinetic properties of the accumulation tein binding on in vivo activity and brain penetration of glycine/ of 3H-raclopride in the mouse brain in vivo. Imaging D2 receptor tween lipophilicity and brain extraction of C-11-labeled radio- occupancy by endogenous dopamine in humans. Regional rat brain distribution ing of amphetamine-induced dopamine release in drug-free of iodinated benzamides. Mapping cocaine binding trations: evidence from a novel positron emission tomography sites in human and baboon brain in vivo. Persistence of haloperi- mine transmission in schizophrenia: confirmation in a second dol in human brain tissue. Removal of en- of the 5-HT1A receptor radioligand, [O-methyl- C]WAY- dogenous dopamine reveals elevation of D2 receptors in schizo- 100635, in rat, monkey and humans plus evaluation of the brain 11 phrenia. Exquisite deline- ligand characteristics and task length for detection of activation. Principles of tracer kinetic modeling in changes with bolus or infusion delivery on neuroreceptor ligands. In: Phelps J Cereb Blood Flow Metab 1998;18:1196–1210. Comparison and autoradiography: principles and applications for the brain and heart. Parameter estimation in positron emission tomogra- receptor. Imaging extrastriatal emission tomography and autoradiography: principles and applica- dopamine D2 receptor occupancy by endogenous dopamine in tions for the brain and heart. Kinetic analysis of central the D2 dopamine receptor in calf brain. Mol Pharmacol 1983; [11C]-raclopride binding to D2 dopamine receptors studied with 25:10–17. Quantification of benzodi- tion by dopamine agonists. Sequestration of dopamine D2 and a single-experiment protocol. J Cereb Blood Flow Metab 1995; receptors depends on coexpression of G protein-coupled receptor 15:284–300. A quantitative model for the in vivo assessment of drug binding sites with posi- binding: evidence for accumulation in corpus striatum by ago- tron emission tomography. Phasic versus tonic dopamine release and modulation 1988;8:291–303. Cortical regulation of subcortical systems and its possi- of the rat: light and electron microscopy. Neuroscience 1995;65: ble relevance to schizophrenia. The regulation of forebrain dopa- cellular distribution of dopamine D2-like receptors: an immuno- mine transmission: relevance to the pathophysiology and psycho- cytochemical study of subtype-specific antibodies in rat and pathology of schizophrenia. Positron emission tomog- of [11C]raclopride: combined PET–microdialysis studies. J Cereb raphy (PET) studies of dopaminergic/cholinergic interactions in Blood Flow Metab 1997;17:932–942. Effects of central cholinergic 424 Neuropsychopharmacology: The Fifth Generation of Progress blockade on striatal dopamine release measured with positron 61. Imaging of the dopa- antagonism on striatal dopamine release in healthy subjects: ap- minergic neurotransmission system using single-photon emission plication of a novel PET approach. Neu- and [I-123]FP-CIT SPECT are useful methods to monitor pro- ropsychopharmacology 1998;18:18–25.
Central 2-adrenergic agonists m ay also stim ulate the peripheral 2- Central α2 I1-Imidazoline adrenergic receptors that m ediate vasoconstriction; this effect predom inates at high plasm a adrenoceptor receptor drug concentrations and may precipitate an increase in blood pressure generic silagra 50 mg otc erectile dysfunction causes lower back pain. The usual physiologic effect is a decrease in peripheral resistance and slowing of the heart rate; however discount 100mg silagra otc erectile dysfunction pills south africa, output is either unchanged or m ildly decreased. Preservation of cardiovascular reflexes prevents postural hypotension. NTS RVLM Nucleus Rostral tractus ventrolateral solitarii medulla Inhibition of central sympathetic activity Blood pressure reduction CENTRAL 2-ADRENERGIC ANTAGONISTS Generic (trade) name First dose, mg Usual daily dose Maximum daily dose Duration of action -Methyldopa (G) (Aldomet) 250 250–1000 mg bid 3000 24–48 h Clonidine (G) (Catapres) 0. The antihypertensive effect results from is adm inistered transderm ally, therapeutic plasm a levels are achieved accumulation of 2-adrenergic receptors, displacing and competing with within 2 to 3 days. M ethyldopa is absorbed poorly Guanabenz, a guanidine derivative, is highly selective for central (<50% ); peak plasm a concentrations occur in 2 to 4 hours. It is absorbed well (>75% ); peak plasm a metabolized in the liver and excreted in the urine mainly as the inactive levels are reached in 2 to 5 hours. The plasma half-life of methyldopa (1 to 2 hours) hepatic metabolism; less than 2% is excreted unchanged in the urine. Clonidine, an im idazoline derivative, acts by stim ulating either Guanfacine is a phenylacetyl-guanidine derivative with a longer central 2-adrenergic receptors or imidazole receptors. It is absorbed well (>90% ); peak be administered orally or by a transdermal delivery system (TTS). The drug is W hen given orally, it is absorbed well (>75% ); peak plasm a con- primarily metabolized in the liver. Guanfacine and its m etabolites centrations occur in 3 to 5 hours. Clonidine is m etabolized m ainly are excreted prim arily by the kidneys; 24% to 37% is excreted as in the liver; fecal excretion ranges from 15% to 30% , and 40% to unchanged drug in the urine. The plasm a half-life (15 to 17 hours) 60% is excreted unchanged in the urine. In patients with renal is not prolonged in patients with renal insufficiency [6,9]. The side 2-ADRENERGIC AGONISTS effect profile of these agents is diverse [6,9]. Side effects Mechanisms Sedation/drowsiness Stimulation of 2-adrenergic receptors in the brain Xerostoniia (dry mouth) Centrally mediated inhibition of cholinergic transmission Gynecomastia in men, galactorrhea Reduced central dopaminergic inhibition in women of prolactin release (methyldopa only) Drug fever, hepatotoxicity, positive Long-term tissue toxicity Coombs test with or without (methyldopa only) hemolytic anemia Sexual dysfunction, depression, Stimulation of 2-adrenergic receptor decreased mental acuity in the brain “Overshoot hypertension” Acute excessive sympathetic discharge Restlessness in the face of chronic downregulation Insomnia of central 2-adrenergic receptors in Headache an inhibitory circuit during chronic Tremor treatment when treatment is stopped Anxiety Nausea and vomiting A feeling of impending doom Indicates blockade FIGURE 7-18 Brain stem Central and peripheral adrenergic neuronal blocking agents. Rauwolfia alkaloids act both within the central nervous system and in the peripheral sympathetic nervous system [6,9]. They effectively Preganglionic deplete stores of norepinephrine (N E) by com petitively inhibiting neuron the uptake of dopam ine by storage granules and by preventing the Ganglion incorporation of norepinephrine into the protective chrom affin granules; the free catecholam ines are destroyed by m onoam ine oxidase. The predom inant pharm acologic effect is a m arked Postganglionic decrease in peripheral resistance; heart rate and cardiac output adrenergic are either unchanged or m ildly decreased. NE nerve ending NE NE β1 α1 α2 Vascular smooth muscle cells Pharmacologic Treatment of Hypertension 7. Reserpine pressure is m axim ally lowered 2 to 3 weeks after beginning therapy. It is absorbed poorly Reserpine is metabolized by the liver; 60% of an oral dose is recovered (approxim ately 30% ); peak plasm a concentrations occur in 1 to 2 in the feces. Less than 1% is excreted in the urine as unchanged drug. Catecholam ine depletion begins within 1 hour of drug The plasm a half-life (12 to 16 days) is not prolonged in patients adm inistration and is m axim al in 24 hours. Blood Peripheral Indicates blockade THE SIDE EFFECT PROFILE OF RESERPINE adrenergic nerve ending Side effects Mechanisms Altered CNS function Depletion of serotonin and/or NE Inability to concentrate catecholamine Decrease mental acuity Sedation Sleep disturbance Depression Nasal congestion/rhinitis Cholinergic effects NE Increased GI motility, Cholinergic effects increased gastric acid secretion NE Increased appetite/weight gain Unknown Sexual dysfunction Unknown Impotence NE Decreased libido β1 α2 α1 FIGURE 7-20 Vascular smooth muscle cells The side effect profile of the central and peripheral adrenergic neuronal blocking agents [10,13]. Reserpine is contraindicated in patients with a history of depression or peptic ulcer disease. The net physiologic effect is a decrease in peripheral resistance; reflex tachycardia and the attendant increase in cardiac output do not predictably occur. This is due to their low affinity for prejunctional 2-adrenergic receptors, which m odulate the local control of nor- epinephrine release from sym pathetic nerve term inals by a negative feedback m echanism (see Fig. N erve activity releases containing NA the endogenous neurotransm itter noradren- Postganglionic Nerve impulse aline (N A) and also adrenaline from the sympathetic neuron induces Sympathetic varicosities. N oradrenaline and adrenaline exocytotic NA release + – C-fiber reach the postsynaptic -adrenoceptors (or Presynaptic β Presynaptic -adrenoceptors) on the cell m em brane of β-receptor α-receptor the target organ by diffusion.
The profile of signaling molecules varies HT receptor has been shown to couple in a pertussis 2C from cell to cell generic 100 mg silagra visa erectile dysfunction drugs history, offering diverse signaling possibilities and toxin-sensitive manner to G in Xenopus oocytes (e 50mg silagra sale erectile dysfunction treatment acupuncture. In con- receptor activation of phospholipase C is cell-type depen- trast, recent evidence suggests that phospholipase C activa- dent; this signal is mediated by G protein subunits and tion in a native setting (choroid plexus) is mediated entirely thus requires the presence of a -regulated phospholipase by G coupling (167). The subunits, generated by dissociation of to G with subsequent cytoskeletal rearrangement has been 13 the heterotrimeric Gi protein, also activate the type 2 iso- recently described in a transfected cell line (168). This activation is conditional, evidence suggests that 5-HT2A and 5-HT2C receptors cou- dependent on the coactivation by G s (i. Phospholipase A2 is a well-characterized inde- ing actions of G i and G do not offset each other. The pendent signal transduction pathway that leads to arachi- answer may lie in the details. In addition to the large family donic acid, with subsequent prostaglandin and leukotriene of G proteins (21 subunits, 5 subunits, and 11 sub- formation (169). Most of these in vascular smooth muscle and is also thought to be inde- molecules are found in the central nervous system. The G pendent of phospholipase C activation (170,171). The 5- protein that contributes activation of type 2 adenylate HT2Areceptor increases phospholipase D activity via a small cyclase is G i1 or G i2 heterotrimer (160), whereas all three G-protein ARF (adenosine diphosphate ribosylation factor) G i subunits ( i3 i2 i1) have the ability to inhibit pathway, with protein kinase C activation being the princi- adenylate cyclase types 5 and 6 (161). This type brain-derived neurotrophic factor expression in hippocam- of interaction has been shown to occur in brain, in which pus (173,174). In addition, a 5-HT2A receptor-mediated G -linkedi receptors enhance -adrenergic responses (162); increase in transforming growth factor- 1, secondary to a similar interaction may take place in cells that coexpress a 5-HT receptor family member with one of the 5-HT protein kinase C activation, has been described (175). The 1A receptors (5-HT , 5-HT , or 5-HT ) linked to activation 5-HT2A and 5-HT2C receptors elicit region-specific in- 4 6 7 of adenylate cyclase. Extensive, complex cross-talk between the 5-HT2A ond messenger pathways defined in brain, the 5-HT recep- and 5-HT2B receptor and the 5-HT1B/D receptor has been 4 tor was one of the last 5-HT receptors to be cloned (143). In transfected cells, the 5-HT6 receptor couples tion (177). Coactivation of the 5-HT2A receptor blocks this to adenylate cyclase type 5, the typical G s-sensitive isoform interaction by an unknown mechanism. In contrast, the 5-HT7receptor increases intracellular parallel, interacting, and converging intracellular signaling calcium, which activates calmodulin-stimulated adenylate pathways illustrate the complexity of receptor signaling, cyclase type 1 or 8. A recent characterization of rat hippo- even within a single receptor subclass. Examples of potential converging and interacting signaling pathways for 5-hydroxy- tryptamine-receptorsubtypes. Thisfigureillustrates onlyafew ofthenearly unlimitedpossibilities, depending on the cell phenotype. Also listed are additional effectors activated by one or another of these receptors with pathways of activation that have not yet been determined. Physiologic Correlates below for 5-HT1, 5-HT2, and 5-HT4 receptors, for which intracellular transduction pathways have been studied most In general, the electrophysiologic effects of 5-HT corre- intensively. The G /Gi o-coupled 5-HT1 5-HT1 Receptors receptors generally mediate inhibitory effects on neuronal firing through an opening of inwardly rectifying K chan- The opening of K channels via 5-HT1A receptors in dorsal nels or a closing of voltage-gated Ca2 channels. Inhibitions raphe neurons is mediated by pertussis toxin-sensitive G mediated by 5-HT1 receptors have been observed in neu- proteins (178,179). The molecular mechanisms underlying rons located in diverse regions of the central nervous system, the opening of K channels are most likely common to all ranging from pyramidal cells of the cerebral cortex and hip- neurotransmitter receptors that couple through the G /Gi o pocampus to serotoninergic neurons of the brainstem raphe family of G proteins. The Gq/11-coupled 5-HT2 family of receptors gener- activate a pertussis toxin-sensitive G protein that couples to ally mediates slow excitatory effects through a decrease in the opening of inwardly rectifying K channels through a K conductance or an increase in nonselective cation con- membrane-delimited pathway (74,180). Slow excitatory effects mediated by 5-HT2 recep- cepted that the rather than subunits regulate the chan- tors have been observed in a number of regions, including nels (181–183). The effector mechanism that ultimately the spinal cord and brainstem (e. Interestingly, at least where these receptors are most concentrated. The 5-HT one of the potassium K subunits identified in heart, 3 receptors, which are ligand-gated channels with structural GIRK-1, is expressed at high levels in hippocampus (184), homology to nicotinic cholinergic receptors, mediate fast which suggests that it might be involved in mediating the excitatory effects of 5-HT.
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