Effects of opioids on human serotonin transporters.

The serotonin (5-hydroxtryptamine, 5-HT) system plays a role in analgesia and emesis. The aim of this study was to test whether opioids or ketamine inhibit the human 5-HT transporter and whether this increases free plasma 5-HT concentrations. HEK293 cells, stably transfected with the human 5-HT transporter cDNA, were incubated with morphine, hydromorphone, fentanyl, alfentanil, pethidine (meperidine), tramadol, ketamine, and the reference substance citalopram (specific 5-HT transporter inhibitor). The uptake of [(3)H]5-HT was measured by liquid scintillation counting. In a second series of experiments, study drugs were incubated with plasma of ten healthy blood donors and change of 5-HT plasma-concentrations were measured (ELISA). The end point was the inhibition of the 5-HT transporter by different analgesics either in HEK293 cells or in human platelets ex vivo. Tramadol, pethidine, and ketamine suppressed [(3)H]5-HT uptake dose-dependently with an IC50 of 1, 20.9, and 230 μM, respectively. These drugs also prevented 5-HT uptake in platelets with an increase in free plasma 5-HT. Free 5-HT concentrations in human plasma were increased by citalopram 1 μM, tramadol 20 μM, pethidine 30 μM, and ketamine 100 μM to 280 [248/312]%, 269 [188/349]%, and 149 [122/174]%, respectively, compared to controls without any co-incubation (means [95 % CI]; all p < 0.005). No change in both experimental settings was observed for the other opioids. Tramadol and pethidine inhibited the 5-HT transporter in HEK293 cells and platelets. This inhibition may contribute to serotonergic effects when these opioids are given in combination, e.g., with monoamine oxidase inhibitors or selective serotonin reuptake inhibitors.

Eosinophilia in Dermatologic Disorders

Eosinophil infiltration can be observed in skin disorders, such as allergic/immunologic, autoimmune, infectious, and neoplastic diseases. Clinical presentations are variable and include eczematous, papular, urticarial, bullous, nodular, and fibrotic lesions; pruritus is a common symptom in all. In this review, we present representative eosinophilic skin diseases according to their clinical pattern, together with histologic findings and diagnostic procedures. We also discuss the potential roles of eosinophils in the pathogenesis of dermatologic disorder. Current pathogenesis-based diagnostic and therapeutic approaches are outlined.

Modulatory Effects of Eschscholzia californica Alkaloids on Recombinant GABAA Receptors.

The California poppy (Eschscholzia californica Cham.) contains a variety of natural compounds including several alkaloids found exclusively in this plant. Because of the sedative, anxiolytic, and analgesic effects, this herb is currently sold in pharmacies in many countries. However, our understanding of these biological effects at the molecular level is still lacking. Alkaloids detected in E. californica could be hypothesized to act at GABAA receptors, which are widely expressed in the brain mainly at the inhibitory interneurons. Electrophysiological studies on a recombinant α 1 β 2 γ 2 GABAA receptor showed no effect of N-methyllaurotetanine at concentrations lower than 30 μM. However, (S)-reticuline behaved as positive allosteric modulator at the α 3, α 5, and α 6 isoforms of GABAA receptors. The depressant properties of aerial parts of E. californica are assigned to chloride-current modulation by (S)-reticuline at the α 3 β 2 γ 2 and α 5 β 2 γ 2 GABAA receptors. Interestingly, α 1, α 3, and α 5 were not significantly affected by (R)-reticuline, 1,2-tetrahydroreticuline, codeine, and morphine-suspected (S)-reticuline metabolites in the rodent brain.

Medical, psychological and socio-economic implications of chronic hand eczema: a cross-sectional study.

BACKGROUND Hand eczema (HE) is a common skin disease with major medical psychological and socio-economic implications. Onset and prognosis of HE are determined by individual as well as environmental factors. So far, most epidemiological data on HE have been reported from Scandinavian and recently German studies. OBJECTIVE To investigate the characteristics and medical care of patients with chronic HE (CHE) in Switzerland, and identify risk factors. METHODS In this cross-sectional study, data from patients with chronic HE were obtained by means of medical history, dermatological examination and patient questionnaires. Multiple logistic regression analysis was applied to identify risk factors for high severity and dermatology life quality index (DLQI). RESULTS In seven dermatology departments, 199 patients (mean age 40.4 years, 50.8% female) with CHE (mean duration 6.6 years) were enrolled. Moderate to severe HE was reported by 70.9% of patients, and was associated with age <30 or >50 years, localization of lesions and pruritus. Because of the CHE, 37.3% of patients were on sick leave over the past 12 months, 14.8% had changed or lost their job. Practically all patients applied topical therapy, 21% were treated with alitretinoin, and 21% with psoralen plus UVA light (PUVA). The effects on the health-related quality of life was moderate to large in 33.7% and 39.4% of CHE patients, respectively. Factors associated with a high impact on DLQI (mean 9.7 ± 5.8) were female sex, lesions on back of the hands and pruritus as well as mechanical skin irritation and wearing gloves. CONCLUSION In agreement with recent studies, the Swiss data demonstrate the high impact of CHE on medical well-being, patient quality of life and work ability. As it is associated with an intense use of health care services, high rate of sick leave, job loss and change, CHE may cause a high socio-economic burden.

Childhood sexual victimization: Risk factor for drug use and sexual risk behaviors

The purpose of this dissertation was to survey men in the Harris County Jail (HCJ) to establish a more valid estimate of childhood sexual abuse (CSA) prevalence in a jailed-based population; to assess whether inmates with a history of CSA were at greater risk for use of drugs and alcohol and engaging in high-risk sexual behaviors than those without histories of childhood sexual abuse. ^ The first study determined the prevalence of childhood sexual abuse among incarcerated males in a county jail. In this study, sixty-three percent of the subjects reported having been sexually abused. Sixty-one percent reported abuse pre-puberty and 10% reported abuse post puberty. In pre-puberty abuse the initiation of first abuse occurred at a mean age of 5.6 years (SD 5.096, range: 2–13 years). ^ The second study explored the association between inmates with histories of CSA as a risk factor for sexual risk behaviors. A history of sexual abuse did not appear to be associated with an elevated risk of sexual risk behaviors. ^ The third study explored a history of drug use and a history of CSA among the inmates. A chi-square test showed that the inmates who reported a history of CSA, was significantly greater for the following drugs: Marijuana (02), Crack (03), Heroin/Morphine (.03), Amphetamines/Speed (01), Downers/Barbiturates (.001), Methamphetamine/Crystal Meth (.001), Valium .02), LSD/Acid (.001), and Inhalants (.001), p < .05). Significance was not found in alcohol, tobacco, cocaine, Quaaludes and methadone. ^ The research from this study provides empirical data supporting previous research. The current data shows that incarcerated inmates have a high prevalence of childhood sexual abuse and drug use. Sexual victimization as a child does not appear to be associated with an elevated risk of unsafe sexual behaviors. However, men who used drugs were twice as likely to have engaged in unprotected sex with casual and regular partners, and rarely used condoms with paid sex. Although our study methods do not permit a causal explanation for this association, we believe it is of concern. Finally, data in this study shows that sexually abused children are likely candidates for adult criminal behavior. ^

Association between ethnicity and treatment status in opioid dependence therapy using methadone and suboxone drugs

Opioids are drugs with opium-like qualities that are either derived from opiates (drugs created from opium, such as morphine or codeine) or chemically produced. In the U.S. opiate abuse and related deaths have been increasing and traditional maintenance treatment has been Methadone with variable success. However, since 2003 synthetic Buprenorphine has been used since it is prescribed daily by physicians in pill form and should improve outcomes. Comparative studies are limited and the effect of ethnicity on treatment outcome is unknown. ^ Data collected at one clinic from December 2005 through May 2009 were used to compare the association between ethnicity and other socioeconomic variables with treatment status, and to identify factors associated with the dropout among participants. Descriptive tables and multiple logistic regression models were used to examine the data on 1,295 total participants. Of the total, 875 participants (68%) were from the Methadone subsample and 420 participants (32%) from the Buprenorphine subsample; only about 15% stayed in treatment. ^ This study showed that with either Methadone or Buprenorphine maintenance therapy, only about 15% participants stay active over 3.5 years. Methadone treated patients that stayed active in treatment were associated with Caucasian ethnicity and were more likely to be employed. With Buprenorphine maintenance treatment only age over 40 years was associated with continuing activity in the program. Further studies that examine the reasons for the high dropout status and the implication of the socioeconomic and ethnic associations found in this data may help to improve treatment outcomes.^

CHARACTERIZATION OF SELECTIVE INHIBITION OF ADENYLYL CYCLASE ACTIVITY BY SMALL MOLECULE INHIBITOR NKY80

The nine membrane-bound isoforms of adenylyl cyclase (AC), via synthesis of the signaling molecule cyclic AMP (cAMP), are involved in many isoform specific physiological functions. Decreasing AC5 activity has been shown to have potential therapeutic benefit, including reduced stress on the heart, pain relief, and attenuation of morphine dependence and withdrawal behaviors. However, AC structure is well conserved, and there are currently no isoform selective AC inhibitors in clinical use. P-site inhibitors inhibit AC directly at the catalytic site, but with an uncompetitive or noncompetitive mechanism. Due to this mechanism and nanomolar potency in cell-free systems, attempts at ligand-based drug design of novel AC inhibitors frequently use P-site inhibitors as a starting template. One small molecule inhibitor designed through this process, NKY80, is described as an AC5 selective inhibitor with low micromolar potency in vitro. P-site inhibitors reveal important ligand binding “pockets” in the AC catalytic site, but specific interactions that give NKY80 selectivity are unclear. Identifying and characterizing unique interactions between NKY80 and AC isoforms would significantly aid the development of isoform selective AC inhibitors. I hypothesized that NKY80’s selective inhibition is conferred by AC isoform specific interactions with the compound within the catalytic site. A structure-based virtual screen of the AC catalytic site was used to identify novel small molecule AC inhibitors. Identified novel inhibitors are isoform selective, supporting the catalytic site as a region capable of more potent isoform selective inhibition. Although NKY80 is touted commercially as an AC5 selective inhibitor, its characterization suggests strong inhibition of both AC5 and the closely related AC6. NKY80 was also virtually docked to AC to determine how NKY80 binds to the catalytic site. My results show a difference between NKY80 binding and the conformation of classic P-site inhibitors. The selectivity and notable differences in NKY80 binding to the AC catalytic site suggest a catalytic subregion more flexible in AC5 and AC6 that can be targeted by selective small molecule inhibitors.

Manejo del dolor en pacientes hospitalizados

Objetivos: Evaluar efectividad y adecuación de la terapia analgésica en pacientes internados con dolor. Materiales y Métodos: Estudio transversal, descriptivo y observacional, mediante revisión de historias clínicas y encuesta validada que incluye el Brief Pain Inventory (BPI). Consideramos respuesta analgésica adecuada un valor ≤ 3 (0-10). Criterio de inclusión: paciente internado con dolor. Análisis estadístico: medidas de tendencia central y dispersión, IC95%. Resultados: Se incluyeron 139 pacientes, distribuidos en clínica médica 13.67%, cardiología 2.88%, cirugía 38.13%, quemados 1.44%, ginecología 9.35%, maternidad 9.35%, traumatología 20.14%, neurología 0.72% y urología 2.16%. Edad media 43.40 años (DS±17.52); 41.73% hombres. Mediana de permanencia al momento de evaluación 3 días (1-60). Presentaron dolor somático 56.83% (IC95% 65.07-48.60), visceral 39.57% (IC95% 47.70-31.44) y neuropático 5.04% (IC95% 8.67-1.40). Las principales etiologías del dolor fueron patología quirúrgica aguda 31.65% (IC95% 39.39-23.92), traumatológica 20.14% (IC95% 26.81-13.48), postoperatorio 17.99% (IC95% 24.37-11.60) y neoplásico 10.07% (IC95% 15.08-5.07). El 82.73% (IC95% 89.02-76.45) tenía indicada analgesia, 47.48% endovenosa y en 3.60% participó especialista en dolor. La dosis fue adecuada en 65.47%; el analgésico más indicado diclofenac 36.69%, ketorolac 16.55%, tramadol 6.47%, paracetamol 5.76%, ibuprofeno 2.16%. Recibía morfina 3.60%, AINE combinado con opioide débil 11.51%, corticoides 3.60% y 0.72% anticonvulsivantes. El 3.60% reportó efectos colaterales atribuibles a la analgesia. Mediante BPI el 38% controló su peor dolor y 53% su valor promedio. Existió demora mayor a 24 hs en indicación de analgesia en 7.91%. La analgesia aplicada figuraba en historia clínica en 40.29%, en indicaciones para enfermería 82.73%. La valoración del dolor fue registrada en 46.76% de las evoluciones diarias.

Role for G protein-coupled receptor kinase in agonist-specific regulation of μ-opioid receptor responsiveness

The G protein-coupled μ-opioid receptor (μOR) mediates the physiological effects of endogenous opioid peptides as well as the structurally distinct opioid alkaloids morphine and etorphine. An intriguing feature of μOR signaling is the differential receptor trafficking and desensitization properties following activation by distinct agonists, which have been proposed as possible mechanisms related to opioid tolerance. Here we report that the ability of distinct opioid agonists to differentially regulate μOR internalization and desensitization is related to their ability to promote G protein-coupled receptor kinase (GRK)-dependent phosphorylation of the μOR. Although both etorphine and morphine effectively activate the μOR, only etorphine elicits robust μOR phosphorylation followed by plasma membrane translocation of β-arrestin and dynamin-dependent receptor internalization. In contrast, corresponding to its inability to cause μOR internalization, morphine is unable to either elicit μOR phosphorylation or stimulate β-arrestin translocation. However, upon the overexpression of GRK2, morphine gains the capacity to induce μOR phosphorylation, accompanied by the rescue of β-arrestin translocation and receptor sequestration. Moreover, overexpression of GRK2 also leads to an attenuation of morphine-mediated inhibition of adenylyl cyclase. These findings point to the existence of marked differences in the ability of different opioid agonists to promote μOR phosphorylation by GRK. These differences may provide the molecular basis underlying the different analgesic properties of opioid agonists and contribute to the distinct ability of various opioids to induce drug tolerance.

Receptors induce chemotaxis by releasing the βγ subunit of Gi, not by activating Gq or Gs

Many chemoattractants cause chemotaxis of leukocytes by stimulating a structurally distinct class of G protein-coupled receptors. To identify receptor functions required for chemotaxis, we studied chemotaxis in HEK293 cells transfected with receptors for nonchemokine ligands or for interleukin 8 (IL-8), a classical chemokine. In gradients of the appropriate agonist, three nonchemokine Gi-coupled receptors (the D2 dopamine receptor and opioid μ and δ receptors) mediated chemotaxis; the β2-adrenoreceptor and the M3-muscarinic receptor, which couple respectively to Gs and Gq, did not mediate chemotaxis. A mutation deleting 31 C-terminal amino acids from the IL-8 receptor type B quantitatively impaired chemotaxis and agonist-induced receptor internalization, but not inhibition of adenylyl cyclase or stimulation of mitogen-activated protein kinase. To probe the possible relation between receptor internalization and chemotaxis, we used two agonists of the μ-opioid receptor. Morphine and etorphine elicited quantitatively similar chemotaxis, but only etorphine induced receptor internalization. Overexpression of two βγ sequestering proteins (βARK-ct and αt) prevented IL-8 receptor type B-mediated chemotaxis but did not affect inhibition of adenylyl cyclase by IL-8. We conclude that: (i) Nonchemokine Gi-coupled receptors can mediate chemotaxis. (ii) Gi activation is necessary but probably not sufficient for chemotaxis. (iii) Chemotaxis does not require receptor internalization. (iv) Chemotaxis requires the release of free βγ subunits.

Suppression of glucocorticoid secretion and antipsychotic drugs have similar effects on the mesolimbic dopaminergic transmission

Specific antagonists of central dopaminergic receptors constitute the major class of antipsychotic drugs (APD). Two principal effects of APD are used as criteria for the pre-clinical screening of their antipsychotic action: (i) inhibition of basal and depolarization-induced activity of mesolimbic dopaminergic neurons; (ii) antagonism of the locomotor effects of dopaminergic agonists. Given that glucocorticoid hormones in animals increase dopamine release and dopamine-mediated behaviors and that high levels of glucocorticoids can induce psychotic symptoms in humans, these experiments examined whether inhibition of endogenous glucocorticoids might have APD-like effects on mesolimbic dopaminergic transmission in rats. It is shown that suppression of glucocorticoid secretion by adrenalectomy profoundly decreased (by greater than 50%): (i) basal dopaminergic release and the release of dopamine induced by a depolarizing stimulus such as morphine (2 mg/kg, s.c.), as measured in the nucleus accumbens of freely moving animals by microdialysis; (ii) the locomotor activity induced by the direct dopaminergic agonist apomorphine. The effects of adrenalectomy were glucocorticoid specific given that they were reversed by the administration of glucocorticoids at doses within the physiological range. Despite its profound diminution of dopaminergic neurotransmission, adrenalectomy neither modified the number of mesencephalic dopaminergic neurons nor induced gliosis in the mesencephalon or in the nucleus accumbens, as shown by tyrosine hydroxylase and glial fibrillary acidic protein immunostaining. In conclusion, these findings suggest that blockade of central effects of glucocorticoids might open new therapeutic strategies of behavioral disturbances.

Loss of signaling through the G protein, Gz, results in abnormal platelet activation and altered responses to psychoactive drugs

Heterotrimeric G proteins mediate the earliest step in cell responses to external events by linking cell surface receptors to intracellular signaling pathways. Gz is a member of the Gi family of G proteins that is prominently expressed in platelets and brain. Here, we show that deletion of the α subunit of Gz in mice: (i) impairs platelet aggregation by preventing the inhibition of cAMP formation normally seen at physiologic concentrations of epinephrine, and (ii) causes the mice to be more resistant to fatal thromboembolism. Loss of Gzα also results in greatly exaggerated responses to cocaine, reduces the analgesic effects of morphine, and abolishes the effects of widely used antidepressant drugs that act as catecholamine reuptake inhibitors. These changes occur despite the presence of other Giα family members in the same cells and are not accompanied by detectable compensatory changes in the level of expression of other G protein subunits. Therefore, these results provide insights into receptor selectivity among G proteins and a model for understanding platelet function and the effects of psychoactive drugs.

Respiratory effects of dexmedetomidine in the surgical patient requiring intensive care

The respiratory effects of dexmedetomidine were retrospectively examined in 33 postsurgical patients involved in a randomised, placebo-controlled trial after extubation in the intensive care unit (ICU). Morphine requirements were reduced by over 50% in patients receiving dexmedetomidine. There were no differences in respiratory rates, oxygen saturations, arterial pH and arterial partial carbon dioxide tension (PaCO2) between the groups. Interestingly the arterial partial oxygen tension (PaO2) : fractional inspired oxygen (FIO2) ratios were statistically significantly higher in the dexmedetomidine group. Dexmedetomidine provides important postsurgical analgesia and appears to have no clinically important adverse effects on respiration in the surgical patient who requires intensive care.

A visceral pain pathway in the dorsal column of the spinal cord

A limited midline myelotomy at T10 can relieve pelvic cancer pain in patients. This observation is explainable in light of strong evidence in support of the existence of a visceral pain pathway that ascends in the dorsal column (DC) of the spinal cord. In rats and monkeys, responses of neurons in the ventral posterolateral thalamic nucleus to noxious colorectal distention are dramatically reduced after a lesion of the DC at T10, but not by interruption of the spinothalamic tract. Blockade of transmission of visceral nociceptive signals through the rat sacral cord by microdialysis administration of morphine or 6-cyano-7-nitroquinoxaline-2,3-dione shows that postsynaptic DC neurons in the sacral cord transmit visceral nociceptive signals to the gracile nucleus. Retrograde tracing studies in rats demonstrate a concentration of postsynaptic DC neurons in the central gray matter of the L6-S1 spinal segments, and anterograde tracing studies show that labeled axons ascend from this region to the gracile nucleus. A similar projection from the midthoracic spinal cord ends in the gracile and cuneate nuclei. Behavioral experiments demonstrate that DC lesions reduce the nocifensive responses produced by noxious stimulation of the pancreas and duodenum, as well as the electrophysiological responses of ventral posterolateral neurons to these stimuli. Repeated regional blood volume measurements were made in the thalamus and other brain structures in anesthetized monkeys in response to colorectal distention by functional MRI. Sham surgery did not reduce the regional blood volume changes, whereas the changes were eliminated by a DC lesion at T10.

Agonist-selective endocytosis of mu opioid receptor by neurons in vivo.

Opiate alkaloids are potent analgesics that exert multiple pharmacological effects in the nervous system by activating G protein-coupled receptors. Receptor internalization upon stimulation may be important for desensitization and resensitization, which affect cellular responsiveness to ligands. Here, we investigated the agonist-induced internalization of the mu opioid receptor (MOR) in vivo by using the guinea pig ileum as a model system and immunohistochemistry with an affinity-purified antibody to the C terminus of rat MOR. Antibody specificity was confirmed by the positive staining of human embryonic kidney 293 cells transfected with epitope-tagged MOR cDNA, by the lack of staining of cells transfected with the delta or kappa receptor cDNA, and by the abolition of staining when the MOR antibody was preadsorbed with the MOR peptide fragment. Abundant MOR immunoreactivity (MOR-IR) was localized to the cell body, dendrites, and axonal processes of myenteric neurons. Immunostaining was primarily confined to the plasma membrane of cell bodies and processes. Within 15 min of an intraperitoneal injection of the opiate agonist etorphine, intense MOR-IR was present in vesicle-like structures, which were identified as endosomes by confocal microscopy. At 30 min, MOR-IR was throughout the cytoplasm and in perinuclear vesicles. MOR-IR was still internalized at 120 min. Agonist-induced endocytosis was completely inhibited by the opiate antagonist naloxone. Interestingly, morphine, a high-affinity MOR agonist, did not cause detectable internalization, but it partially inhibited the etorphine-induced MOR endocytosis. These results demonstrate the occurrence of agonist-selective MOR endocytosis in neurons naturally expressing this receptor in vivo and suggest the existence of different mechanisms regulating cellular responsiveness to ligands.