Friday, October 13, 2017
Latest Posts
GMT+6 11:46


By C. Ismael. Indiana University - Purdue University, Indianapolis. 2018.

Jacobs and Fornal (12) conclude that serotonin facilitates Different species may manifest a range of different kinds gross motor output and inhibits sensory information pro- of SIB (20) cheap dapoxetine 30mg with amex. Psychogenic alopecia is found in cats discount dapoxetine 60mg on line, with cessing. Certainly, isolation may be associated with de- excessive depilation leading to bare patches. Furthermore, in confining in birds is seen in a range of avian species, and can be or depriving environments, the animal may activate dorsal complicated by severe hemorrhage. Although stereotypies raphe neurons by performance of stereotypies (12). Indeed, it has been suggested that excessive opioid activity is responsible for SIB (15). However, an alternative Neurochemistry hypothesis emphasizes that pain associated with SIB results in the release of brain endorphins and draws a parallel be- The pharmacotherapeutic profile of acral lick dermatitis tween such endogenous release of endorphins and addiction overlaps remarkably neatly with that of obsessive-compul- to an exogenous substance (16). Thus, the disorder responds to From an integrated brain-mind perspective, interactions selective serotonin reuptake inhibitors (SSRIs), but fails to and overlaps between environmental and pharmacologic in- respond to desipramine or fenfluramine. However, the dis- ducers of stereotypy would be predicted. Indeed, compared order may also respond to opioid agents. Although not well to normally reared rodents, isolation-reared subjects show studied pharmacologically, there are a number of reports increased stereotypic responses after administration of am- indicating that psychogenic alopecia responds to treatment phetamine (17) or tail-pinch (18). In addition, administration of a dopamine blocker has been noted to lead to a decrease in symptoms. Similarly, feather-picking in birds and SIB in horses may Neuroanatomy respond to treatment with SSRIs (20). There is evidence that corticostriatal circuits are important We noted earlier the cross-sensitization between pharma- in mediating stereotypic behavior (3). First, infusion of the cologic and environmental inducers of stereotypies (22). Conversely, infusion of do- duced SIB may respond to psychopharmacologic interven- pamine blockers into the same areas reduces amphetamine- tion. For example, in a placebo-controlled study of fluoxe- induced stereotypy. Second, frontal lesions and dopamine tine in isolation-reared primates, this SSRI was effective in agonists produce similar behavioral and cognitive effects, reducing such symptoms (23). Furthermore, striatal lesions may also lead to stereotypic Neuroanatomy behavior. Reviewing this literature and his own work, Ridley (3) concludes that loss of inhibition induced by frontal le- In the previous section, the possible involvement of fronto- sions results in a release of previously stored response se- striatal circuits in animal stereotypic behavior was noted. Chapter 121: Compulsive and Impulsive Aspects of Self-Injurious Behavior 1745 With regard to stereotypic SIB in higher mammals, a partic- disability and symptoms in patients with OCD (28). Fur- ularly interesting finding is that socially isolated primates thermore, as noted earlier, in patients with developmental develop striatal cellular disorganization together with stereo- disability, there are significant positive associations between typic and self-injurious behaviors (24). The neuroanatomy the occurrence of self-injury, stereotypy, and compulsions of early social isolation and other developmental stressors (27). Nevertheless, relatively few studies have directly ex- would seem to be a promising area for further investigation, plored the role of serotonin in mediating SIB in such pa- one that may have direct relevance to some of the clinical tients. There is, however, some evidence of the value of SSRIs in the treatment of SIB in developmental disabled patients. SMD IN DEVELOPMENTAL DISABILITY Aretrospective review suggested that response of SIB in such patients was higher for SSRIs and was not predicted Phenomenology by comorbid depressive symptoms (30). Indeed, both open SIB in patients with developmental disabilities may fall and controlled (31) studies have confirmed the efficacy of within the diagnostic category of SMD. This disorder is SSRIs in the treatment of SIB in developmental disabilities. Examples include body rocking, in the mediation of SIB in mental retardation, questions hand waving, head banging, and skin picking. The DSM- remain about whether the effects of these agents are not IV provides a subtype 'with self-injurious behavior,' to be 'downstream' of their primary actions and about their used when bodily damage requires medical treatment. Several methodologies are available for delineat- have reviewed this disorder elsewhere (25,26), and draw ing different aspects of serotonin dysfunction in psychiatric extensively on those reviews here. It must 'markedly interfere with been useful in showing that serotonin plays a specific role normal activities' or result in 'bodily injury that requires in several disorders characterized by unwanted repetitive medical treatment. Asimilarly designed ity the behavior must be sufficiently severe to be a focus of study in mental retardation patients with SIB would be of treatment, and the behavior must persist for at least 4 weeks. The DSM-IV also states that stereotypic behaviors in SMD It may be noted here that other agents with serotoniner- should not be better accounted for by the compulsions of gic effects have also been studied for the treatment of SIB obsessive-compulsive disorder, the stereotypies of pervasive in developmental disability (28,34). Buspirone (15 to 45 mg/day), a 5-HT1A agonist, always meet the rather strict DSM-IV criteria for SMD.

discount dapoxetine 60mg overnight delivery

Key Points • Based on 3 studies (2 good buy 90 mg dapoxetine, 1 fair quality) involving 271 patients dapoxetine 30mg mastercard, evidence suggests that amiodarone is comparable to the calcium channel blocker diltiazem for rate control (low strength of evidence). These include improvement of AF symptoms in patients receiving combined treatment with carvedilol plus digoxin compared with digoxin alone, rate control in patients using 17 metoprolol versus diltiazem or sotalol, and the safety of any one pharmacological agent used for ventricular rate control in patients with AF. Description of Included Studies A total of 14 RCTs involving 1,017 patients were identified that assessed the use of pharmacological agents for ventricular rate control in patients with AF (Appendix Table F-1). Thirteen studies were published between 2000 and 2006, and one was published 145,147,148,150 138-144,146,149,151 in 2009. Four studies were multicenter and 10 were single-center. Only 151 138-140,142,144-147 one study included a site in the United States; eight included sites in Europe, 143,150 148 141 two included sites in Asia, and one each included sites in Canada, the UK, and 149 Australia/New Zealand. The study population consisted entirely of patients with persistent AF 141,144,145,147 143 in four studies, and entirely of patients with paroxysmal AF in one study. Funding 138-140,142-144,146-148,151 was unclear or not reported in 10 studies. A total of three studies included 141,145,150 funding from industry, two received funding from nongovernment/nonindustry 145,149 sources, and no studies were government-only funded. In eight studies the setting was 139,143,148,149,151 inpatient: five of these were in emergency rooms, and the other three did not 138,140,144 include emergency room patients. In the remaining studies, five were classified as 141,142,146,147,150 145 outpatient, and in one the setting was unclear. Most of the studies included patients with no history of heart failure, and the mean ejection fraction varied from 23. Only a few studies included patients with coronary artery disease. Figure 4 represents the treatment comparisons evaluated for this KQ. Overview of treatment comparisons evaluated for KQ 1 aLines running from one oval back to the same oval (e. Abbreviation: KQ=Key Question 141,146 Two studies compared beta blockers with digoxin, one compared beta blockers with 139 calcium channel blockers, and one compared beta blockers with calcium channel blockers in 150 patients using digoxin. One study compared two beta blockers (sotalol and metoprolol) in 142 patients receiving digoxin. Amiodarone was compared with calcium channel blockers in three 138,143,144 140,143,149 studies, and with digoxin in three. One study evaluated the benefits of adding 151 calcium channel blockers to digoxin compared with digoxin alone, and four studies compared 143,145,147,148 calcium channel blockers with digoxin. Note that although amiodarone and sotalol are evaluated under this KQ for their rate-controlling potential, these agents are also potent membrane-active, type III antiarrhythmics, thereby having potential rhythm-control benefits (and risks). Detailed Synthesis Beta Blockers Versus Digoxin One study compared the beta blocker carvedilol with digoxin in patients with AF and heart 141 failure. The mean ejection fraction was 24 percent, and the study duration was 6 months. The combination of digoxin plus carvedilol was superior to digoxin alone for rate control at 4 months (65. After 4 months, digoxin was stopped in the combined arm and carvedilol alone was compared with digoxin alone. At 6 months, there was no difference in rate control between digoxin alone and carvedilol alone (75. The 19 combination of carvedilol plus digoxin reduced the heart rate through steady-state exercise when compared with digoxin alone (106 bpm vs. Carvedilol alone and digoxin alone were equally effective in controlling heart rate during exercise. Digoxin was more effective than carvedilol in reducing nocturnal heart rate. The improvement of AF symptoms was greater in patients receiving combined treatment with carvedilol plus digoxin than in patients receiving digoxin alone. Three patients receiving carvedilol withdrew from the study due to gastrointestinal disturbance, tiredness, and bronchospasm. Another study compared the beta blocker sotalol with digoxin in patients with AF at rest and 146 during exercise. The heart rate at rest and at 10 minutes after exercise did not differ between the three groups (sotalol alone, digoxin alone, or combination of digoxin plus sotalol). However, the heart rate during maximal exercise was significantly lower in patients receiving sotalol (either alone or in combination with digoxin) than in patients receiving digoxin alone (p<0.

dapoxetine 90mg lowest price

Collectively dapoxetine 60mg with visa, these observations led to the dis- (27–29) buy discount dapoxetine 60mg on line. Phosphorylation of this residue is thought to im- covery of the family of G protein-coupled receptor kinases pair receptor–G protein coupling directly, without a re- (GRKs). According to this nomenclature, rhodopsin is de- quirement for any known protein cofactor such as an ar- noted GRK-1, the originally identified BARK enzyme is restin. An important feature of PKA is that this kinase can denoted GRK-2, and other members of this family of pro- phosphorylate B2ARs whether or not they have been acti- Chapter 5: Regulation of G Protein-Coupled Receptors 63 vated by ligand, in contrast to the preferential phosphoryla- This dynamic cycling of the B2AR was also suggested by tion of agonist-activated receptors by GRK-2. Because PKA elegant studies in which subcellular fractionation and ra- is activated by cAMP, a signaling intermediate produced as dioligand binding techniques were used (33). In addition, because activation tors in the plasma membrane, from a relatively diffuse distri- of any other receptor that stimulates adenylyl cyclase can bution throughout the plasma membrane to a pronounced also activate PKA, phosphorylation of the B2AR by PKA concentration of agonist-activated receptors in structures is generally considered to be a paradigm for heterologous resembling clathrin-coated pits when examined by immu- desensitization (Fig. Furthermore, this process of ligand- regulated concentration of B2ARs in coated pits of the plasma membrane was shown to be mechanistically distinct Rapid Desensitization and from the subsequent endocytosis of receptors by membrane Resensitization Mediated by Regulated fission, which can occur even in the absence of continued Endocytosis of Receptors ligand-induced activation of receptors (34). A protein that Endocytosis of GPCRs by Clathrin-Coated Pits is required for this latter step of endocytic membrane fission is the cytoplasmic guanosine triphosphatase dynamin (35, Studies conducted in cultured cells indicate that many 36). Consistent with this, agonist-induced endocytosis of GPCRs can be regulated by ligand-induced endocytosis. Subse- with respect to endocytic membrane trafficking. Early evi- quent studies have demonstrated that regulated endocytosis dence for agonist-induced endocytosis of the B2AR was sug- of several other GPCRs is also mediated by a dynamin- gested by observations from subcellular fractionation and dependent mechanism, which suggests a conserved role of radioligand binding assays conducted with membrane-im- clathrin-coated pits in the endocytosis of many GPCRs (Fig. Endocytosis by Clathrin-Coated Pits The development of receptor-specific antibodies allowed the application of immunocytochemical methods to visual- Studies elucidating the mechanism mediating the key step ize the subcellular localization of the B2AR and directly of regulated concentration of GPCRs in clathrin-coated pits demonstrate agonist-induced internalization of the receptor were initiated by the observation that GRK-mediated phos- protein. Internalization of the B2AR was observed to repre- phorylation of the M2 muscarinic acetylcholine receptor sent a steady state of a highly dynamic process involving can promote agonist-induced endocytosis of the receptor, continuous endocytosis and recycling of receptors through whereas a kinase-defective mutant form of GRK inhibits an endocytic pathway similar to that mediating constitutive this process (39). Similar observations were made for other (ligand-independent) endocytosis of nutrient receptors (32). Regulated endocytosis of the 2-adrenergic receptor (B2AR) by clathrin-coated pits. G protein-coupled re- ceptor kinase-mediated phosphorylation of the B2AR promotes receptor interaction with nonvisual arrestins, which cause un- coupling of heterotrimeric G proteins and also promote interaction of arrestin–re- ceptor complexes with clathrin coats. Once concentrated in clathrin-coated pits bythis mechanism, receptors undergo endocyto- sis rapidly(even if agonist is removed from the receptor in the coated pit) via a consti- tutive (ligand-independent) mechanism of endocytic membrane fission that requires the cytoplasmic guanosine triphosphatase dynamin. However, as discussed physically linking phosphorylated receptors with clathrin above, rapid desensitization by phosphorylation-dependent (40). This is consistent with the abil- functional uncoupling of receptor from G protein because ity of certain GPCRs, such as the 2A-adrenergic receptor, the latter process can occur in the absence of endocytosis. This distinction between visual and nonvisual Thus, the precise role of endocytosis in contributing to de- arrestins led to the identification of a carboxyl-terminal sensitization of GPCR-mediated signal transduction proba- clathrin-binding domain, present specifically in nonvisual bly varies among systems and may be particularly important arrestins, that is necessary for endocytosis of GPCRs but in cells expressing relatively low numbers of receptors. The most thoroughly studied example of this Functional Role of Endocytosis in the Processes mechanism derives from elegant studies of the B2AR (2, of Rapid Desensitization and Resensitization of 49,50). As discussed above, agonist-induced phosphoryla- GPCRs tion of the B2AR by GRKs causes rapid desensitization by Physiologic ligands are generally thought to bind to GPCRs promoting receptor interaction with arrestins and func- in the plasma membrane. Biochemical and immunocyto- tional uncoupling from heterotrimeric G proteins (Fig. This initial desensitization of receptors occurs in B2AR, interact with heterotrimeric G proteins primarily in the plasma membrane and does not require endocytosis of the plasma membrane but not in intracellular membranes the receptor protein. Within several minutes after this initial after endocytosis (44,45). Together, these observations sug- uncoupling of receptor from heterotrimeric G protein, ar- gest that endocytosis may, by itself, mediate desensitization restins promote the concentration of receptors in clathrin- of GPCR-mediated signal transduction by directly reducing coated pits and subsequent endocytosis (Fig. Endocytic membranes containing internalized FIGURE 5. Linked cycles of G protein-cou- pled receptor phosphorylation and endocyto- sis mediating rapid desensitization and resen- sitization of the 2-adrenergic receptor (B2AR). Agonist-induced activation of the B2AR causes G protein-coupled receptor ki- nase-mediated phosphorylation, which pro- motes receptor interaction with nonvisual ar- restins and uncoupling of heterotrimeric G protein (step 1). Arrestin binding to the phos- phorylated receptor also promotes receptor concentration in clathrin-coated pits (step 2), promoting rapid endocytosis of receptors by dynamin-dependent fission of coated pits from the plasma membrane and subsequent formation of endocytic vesicles (step 3). To- gether, these steps cause profound functional desenstization of signal transduction. Endo- cytic membranes containing internalized B2ARs are associated with a protein phospha- tase (PP2A) that can catalyze dephosphoryla- tion of receptors (step 4). Dephosphorylation of receptors followed byrecycling to the plasma membrane (step 5) mediates the return of receptors to the plasma membrane in a fully functional state, promoting functional resensi- tization of the signal transduction system.

buy discount dapoxetine 90mg online

Across suc- University of Pittsburgh School of Medicine discount dapoxetine 90 mg otc, Pittsburgh generic dapoxetine 90 mg with visa, Pennsylvania. These fast synchronous of Berger (1930), Economo (1929), Bremer (1935), Moru- rhythms may serve a purpose of binding aspects of a stimu- zzi and Magoun (1949), and Jouvet (1962). Importantly, these fast work of these investigators, the state of sleep was thought rhythms as well as the slow rhythms are dependent on the to represent an inactive period for the brain. Berger first level of excitability in local intracortical circuits as may be described electrophysiologic patterns of brain electrical ac- modulated by ascending activating modulatory systems such tivity that correlated with changes in behavioral state. Other as the brainstem monoaminergic and cholinergic nuclei (5). Clinicoanatomic clues of these levels modulating these electrophysiologic rhythms. Finally, following the global ascending activating influences. Arousal and the maintenance of an transections in cats. From these studies it is now recognized aroused state is an active process requiring the integrated that behavioral state is intrinsically regulated and generated activity of a series of arousal systems shown diagrammati- by the brain itself and manifested by electrical activity in cally in Fig. First, the electrical oscillations the pontine cholinergic nuclei, midbrain raphe nuclei, and observed at the macroscopic level are the end result of elec- the locus ceruleus, and into a series of forebrain structures trical oscillations involving widespread thalamocortical involved in arousal. These include the midline and medial neurons that are synchronized in a global fashion. Second, thalamus with widespread cortical projections and the widespread changes in these oscillations can result from amygdala, which has interconnections with isocortex and state-dependent changes in modulatory systems such as the other areas involved in arousal, particularly hypothalamus brainstem, hypothalamus, and basal forebrain. The amygdala is particularly involved oscillations in the 1 to 4 Hz delta range have both cortical with autonomic regulation and the emotional component and thalamic components. There are two important components of the basal that rhythmic oscillations are the end result, therefore, of forebrain–ventral striatum system (10). One is the choliner- integrated corticothalamic circuits and modulatory struc- gic neurons of the medial septum–nucleus of the diagonal tures. Changes in delta sleep found in diverse neuropsychia- band–nucleus basalis complex that innervates the entire tric disorders, therefore, may result from functional changes forebrain. The second is the nucleus accumbens–ventral at one or more levels including the cortex, thalamus, and striatum complex that is involved in transmitting the arous- modulatory structures. Arousal systems in the human brain (see text for description). The transmitters associated with each system are abbreviated. Second, of tonic inhibition from noradrenergic and serotonergic nu- there are extensive hypothalamic projections to isocortex, clei as these monoaminergic nuclei slow or become silent predominantly from posterior hypothalamus. Modifica- a newly discovered projection from a group of neurons that tions of this model now account for the influence of addi- produce a novel peptide hypocretin. Recent work, for physiology of mental disorders may guide theoretical models example, suggests that the amygdala has significant ana- of behavioral state regulation in diverse mental disorders tomic connections and recently established modulatory ef- (see Chapters 128 to 133). This pattern of activation is super- play in cortical arousal. Several studies have discovered that sleep deprivation is asso- ciated with a global reduction in metabolism with some Mechanisms Underlying Behavioral State preference for the prefrontal cortex. This reduction is mag- Changes: Evidence from Human Sleep nified with successive nights of sleep deprivation. These Imaging Studies changes have recently been shown to play a role in the cognitive alterations associated with sleep deprivation (31). The advent of brain imaging methods that can be used to study the functional neuroanatomy of human sleep has recently created a venue for linking preclinical work with human sleep electrophysiology. Several models of sleep/wake regulation attempt to define parameters that may influence the probability at any point Global Changes in Brain Function across in the day that sleep may occur. One such model is the two-process model described by Borbely (32). One process, Behavioral States called process S, describes a homeostatic sleep process. As sleep deprivation in- blood flow or metabolism ranges from 10% below to 41% creases, for example, process S increases and amplifies sleep above levels obtained during wakefulness (23,24). The second process, process C, varies through- report cited a positive correlation between waking global out the day in relation to a sinusoidal circadian phase across and regional cerebral blood flow and slow wave sleep mea- a 24-hour day. The intensity of this sleep propensity is unre- sures from the subsequent night of sleep (25). The authors lated to the amount of prior wakefulness. The sleep parame- interpreted these findings as reflecting an energy conserva- ter most affected by this process is process C; nonsleep corre- tion or restorative role for slow wave sleep. These changes garding forebrain function in information processing.

10 of 10 - Review by C. Ismael
Votes: 283 votes
Total customer reviews: 283