RESUMEN
Asthma is characterized by chronic inflammation of airways. Currently, no traditional method allows an easy daily evaluation of the degree of airway inflammation. Measuring inflammatory biomarkers in the breath is a very attractive approach to monitor asthma inflammation. In recent years, the measurement of exhaled breath temperature (EBT) has been proposed as a method capable of detecting the inflammatory status of the airways. The objective of this study is to strengthen the role of EBT in the diagnosis and monitoring of asthma. The study sample was represented by a group of 40 patients, of both sexes, aged 6-15 years. The elective criteria for submitting patients to EBT determination were abstaining from drugs in the preceding 24 h, fasting for at least 2 h, physical resting for at least 30 minutes, a body temperature between 35-37°C. The temperature in the room of the surveys ranged from 18 to 25°C. The EBT values of asthmatic patients were higher [(median (IQR): 29.77°C (30.67°C to 29.38°C) range 28.46°C min-max 34.78°C] than those of non-asthmatic ones (median (IQR): 28.22°C (29.09°C-27.7°C), range 27.09°C min-max 30.07°C] and this difference was highly significant (p less than 0.001). Furthermore, no significant difference was found between the EBT values of the following groups of patients: those exposed and not exposed to passive smoking, those receiving and not receiving leukotriene drugs, those receiving and not receiving specific immunotherapy, monoallergic patients and poliallergic ones, those sensitized and not sensitized to house dust, perennial allergic patients and seasonal allergic ones. In addition, the evaluation of the correlation of EBT values with body temperature (r=0.119, p=0.464) and ambient temperature (r=-304, p = 0.057) did not show any significant correlation. Finally, no statistically significant correlation was demonstrated between EBT values and FEV1 (r=-0055, p=0.81, Fig. 4). In conclusion, the data of the present study further support the hypothesis that EBT can be considered a good method for monitoring asthma.
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Asthma is one of the most common chronic diseases in children. To date the diagnosis of asthma is mainly clinical, based on the clinical history, a careful physical examination and lung function tests. However, symptoms are often not specific and lung function tests are not very sensitive. In order to find a solution to this problem new biomarkers of airway inflammation are being developed. YKL-40 is a chitinase-like protein that has a role in the inflammation and tissue remodeling in several human diseases. The aim of this study is to evaluate serum levels of YKL40 in children with intermittent or persistent asthma. We performed a cross-sectional analysis of serum samples from a cohort of patients with asthma and healthy controls. Patients with asthma were stratified according to four levels of asthma severity (mild intermittent, mild persistent, moderate persistent, and severe persistent). The analysis of serum samples was performed with the use of a commercially available enzyme-linked immune-adsorbent assay (ELISA) kit (Quidel). The minimum detection limit of the assay for YKL-40 is 15.6 ng per milliliter (ng/ml). Our data showed that circulating YKL-40 levels are significantly higher in patients with asthma than healthy subjects (36±18.6 vs 14:41±2.88, p= 0.001). Furthermore, we found significantly higher values of YKL-40 in both groups of children with intermittent asthma (p less than 0.001) and persistent asthma (p less than 0.001) than healthy controls. However, no correlation was found with duration and severity of asthmatic disease (r = 0:18, p= 0:33, r = 0.28 P = 0:13, respectively). Our data allow us to suggest that YKL-40 represents a useful biomarker of asthma in children with intermittent or persistent asthma.
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The aim of this randomized open study was to evaluate the safety and efficacy of different dosages (2000 UI vs 4000 UI) of sublingual immunotherapy (SLIT) in patients with allergic diseases such as asthma associated to rhinitis and rhinoconjunctivitis sensitized to house dust mites. We enrolled 61 patients with a history of allergic asthma, and a positive skin prick test for Dermatophagoides (D.) pteronyssinus/farinae. Patients were randomly assigned to receiving SLIT at dosage of 2000 UI (Group A) or 4000 UI (Group B) maintenance dose. We evaluated: subjective symptoms using a Visual Analogic Scale (VAS), the amount of prescribed symptomatic drugs, bronchial reactivity to methacoline and side effects using a specific questionnaire. A significant improvement in symptoms, assessed by VAS, was observed with both SLIT doses with no significant differences between groups. The provocation dose of methacoline inducing a 20% fall of FEV1 significantly increased after 12 months only in the 4000 UI dose group. In conclusion, both monomeric allergoid dosages of SLIT (2000 UI and 4000 UI) are a safe and efficacy option to reduce symptoms in patients with allergic asthma caused by house dust mites. Moreover, both dosages are efficacious even to protect against airway reactivity but it seems that monomeric allergoid of SLIT at higher dosage (4000 UI) is better than at the lower dosage (2000 UI).
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YKL-40 (also called chitinase 3-like-1 or human cartilage glycoprotein 39) is a chitinase-like protein belonging to the family 18 of glycosyl hydrolase (GH18). This protein is involved in the inflammatory process acting as pro-inflammatory cytokine secreted by neutrophils, activated human macrophages, vascular smooth muscle cells and cancer cells. It has been shown that YKL-40 has a role in pathological tissue remodeling and development of fibrosis of several diseases. To date, the biological and pathophysiological function of YKL-40 protein in pulmonary diseases is still unclear. This review focuses on the role of YKL-40 in diagnosis and monitoring of different lung diseases in order to assess whether this protein could be used as biomarker of specific conditions featured by inflammation and fibrosis. A comprehensive review of the literature using PubMed database, with appropriate terms, was undertaken for articles in English published since 1997. The literature search was undertaken in October 2014.
RESUMEN
In recent decades, there has been an increase in the prevalence of asthma and obesity in pediatric age. In this regard several studies have provided controversial data to demonstrate the link between Body Mass Index (BMI) and asthma, both in adults and in children. In this prospective study we evaluated the relationship between body mass index value, total IgE immunoglobulin E levels, skin prick test (SPT) sensitization and lung function in children affected by asthma. According to the analysis of data on the comparison of normal-weight patients versus overweight/obese patients, there was no significant difference in the values of FEV1 (86%±12 vs 90%±19), FVC (81%±11 vs 88%±18), skin prick tests (22.72% vs 36.66%) and total IgE values (192.22±368.28 vs 503±914.04). We carried out a sub-analysis to study the difference between three groups of patients: normal weight, overweight and obese. Obese patients showed higher total IgE values than normal-weight patients with a statistically significant difference. Conversely, there was no significant difference between the normal weight group and the obese group in the respiratory function tests and the SPT. Moreover, we found a higher value of total IgE in female overweight/obese compared with normal weight, while there was no significant difference in relation to parameters of lung function and SPT. However, the same analysis in the male sample did not show any statistically significant difference. This study confirms the higher incidence of atopy in obese children, especially in female gender, but not a direct relationship with either allergens sensitization or abnormal lung function.
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BACKGROUND: Several studies have shown increased serum levels of proinflammatory cytokines (IL-1α, IL-6, and TNF-α) in patients with cholelithiasis. The local expression of the proteins involved in pathogenesis of the disease is poorly recognised. MATERIALS AND METHODS: The authors examined immunohistochemically (IHC) the expression status of IL-1α, IL-6, and TNF-α in gallbladder mucosa of the patients with cholelithiasis as related to acute (ACC) and chronic (CCC) types of cholecystitis. Proinflammatory cytokines were quantitatively evaluated in gallbladder mucosa (epithelium and lamina propria) in ACC (n = 16) and CCC (n = 55) groups using modern spatial visualisation technique. RESULTS: Quantitative analysis of IHC signals showed no significant differences in IL-1α and IL-6, and immunoexpression in patients with ACC and CCC. A significantly greater IHC expression of TNF-α was detected in CCC as compared with ACC group. In either of the patient groups immunoexpression of IL-1α and of TNF-α was significantly higher than that of IL-6. Immunoexpression of TNF-α was significantly higher than that of IL-1α only in CCC group. A positive correlation was disclosed between IHC expression of IL-1α and body mass index in CCC group. IHC expression of TNF-α correlated positively with expression of CD68 molecule (histiocytic marker), number of leukocytes in blood and higher grading of gallbladder wall in ACC group. CONCLUSIONS: A more pronounced IHC expression of TNF-α and IL-1α than IL-6 in both types of cholecystitis may suggest the role of these cytokines in pathogenesis of cholelithiasis. IHC expression of TNF- α shows better correlation with clinical/laboratory data in acute cholecystitis, and its quantitative prevalence over the remaining cytokines points to the role of the TNF-α in maintenance of inflammation in the course of cholelithiasis.
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BACKGROUND: Recently, the dual-energy X-ray absorptiometry (DXA) diagnostic cut-off (T-score) for Australian Pharmaceutical Benefits Scheme (PBS) supported primary fracture prevention therapy with alendronate for older women (>70 years) has been changed from -3.0 to -2.5. AIM: To examine the impact of the expanded criteria for PBS-supported fracture prevention therapy in older women on case finding and cost. METHODS: One thousand, nine hundred and eighty-three women, median age 76 years, not previously known to have low bone mineral density by DXA or a vertebral fracture underwent DXA scanning and a thoracolumbar X-ray. A woman was considered eligible for fracture prevention therapy if she had a T-score ≤-2.5 at the femoral neck and/or the lumbar vertebrae (two to four) or at least one vertebral fracture of ≥20% deformity. RESULTS: Seven hundred and forty-six women (37.6%) met the new criteria as a case for PBS-subsidised fracture prevention therapy. Four hundred and thirty-one (21.7%) had a T-score ≤-2.5 on DXA compared with 10.6% (n = 210) with a T-score ≤-3.0. Four hundred and eighty-three (24.4%) had at least one vertebral fracture. Only 8.5% (n = 168) had both a T-score ≤-2.5 and a prevalent vertebral fracture. The cost per case found by DXA equated to $460 compared with $398 for screening by thoracolumbar X-ray. CONCLUSIONS: The use of either DXA or X-ray will identify approximately two-thirds of women aged 70 years and over who would be eligible for fracture prevention. The use of X-ray would identify a marginally larger number of women and at lower financial cost but involve substantially greater radiation exposure.
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Densidad Ósea , Fracturas Espontáneas/prevención & control , Vértebras Lumbares/diagnóstico por imagen , Osteoporosis Posmenopáusica/diagnóstico por imagen , Atención Primaria de Salud/métodos , Fracturas de la Columna Vertebral/prevención & control , Vértebras Torácicas/diagnóstico por imagen , Absorciometría de Fotón/economía , Anciano , Anciano de 80 o más Años , Alendronato/uso terapéutico , Australia/epidemiología , Conservadores de la Densidad Ósea/uso terapéutico , Femenino , Fracturas del Cuello Femoral/prevención & control , Cuello Femoral/diagnóstico por imagen , Fracturas Espontáneas/diagnóstico por imagen , Fracturas Espontáneas/economía , Fracturas Espontáneas/etiología , Humanos , Vértebras Lumbares/lesiones , Tamizaje Masivo , Osteoporosis Posmenopáusica/tratamiento farmacológico , Osteoporosis Posmenopáusica/economía , Osteoporosis Posmenopáusica/epidemiología , Dosis de Radiación , Medición de Riesgo , Fracturas de la Columna Vertebral/diagnóstico por imagen , Fracturas de la Columna Vertebral/economía , Fracturas de la Columna Vertebral/etiología , Vértebras Torácicas/lesionesRESUMEN
The prevalence of the internalization-associated prtF1 gene was studied in 837 isolates of Streptococcus pyogenes obtained from 713 pediatric patients presenting with acute pharyngotonsillitis before and after antibiotic therapy. Its association with macrolide resistance and with bacteriological treatment failure was determined. The bacterial population isolated from baseline pharyngeal swabs showed an overall prtF1 positivity rate of 33%. A higher prtF1 positivity was found among erythromycin-resistant strains (45%) showing, however, marked differences between the inducible (iMLS), constitutive (cMLS), and efflux pump (M) resistance phenotypes. The prevalence was statistically higher (p < 0.001) in strains belonging to iMLS (84%) and cMLS (67%) phenotypes as compared to the M phenotype (15%). Interestingly, the prevalence of the prtF1 gene was significantly lower (p = 0.04) in strains belonging to M resistance phenotype as compared to erythromycin-susceptible strains (28%). Failed bacterial eradication was demonstrated in 124 patients. The prtF1 positivity rate remained unchanged in strains isolated before and after therapy in patients treated with macrolides (9/54). On the other hand, the positivity rate for the prtF1 gene was significantly higher (p = 0.015) in strains isolated after therapy with beta-lactams (21/70) as compared to baseline isolates (6/70), indicating a differential selection imposed on the organism by these agents. Finally, a high overall eradication rate (88%) of prtF1-positive isolates, belonging to both the erythromycin-susceptible and -resistant phenotypes, was demonstrated following macrolide treatment.
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Adhesinas Bacterianas/genética , Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple , Faringitis/microbiología , Streptococcus pyogenes/genética , Tonsilitis/microbiología , Enfermedad Aguda , Antibacterianos/uso terapéutico , Niño , Eritromicina/farmacología , Eritromicina/uso terapéutico , Humanos , Pruebas de Sensibilidad Microbiana , Faringitis/tratamiento farmacológico , Reacción en Cadena de la Polimerasa , Streptococcus pyogenes/efectos de los fármacos , Streptococcus pyogenes/aislamiento & purificación , Tonsilitis/tratamiento farmacológico , Insuficiencia del Tratamiento , beta-Lactamas/farmacología , beta-Lactamas/uso terapéuticoRESUMEN
Signaling pathways for muscarinic acetylcholine receptors (mAChRs) include several enzymes and ion channels. Recent studies have revealed the importance of various isoforms of both alpha and betagamma subunits of G proteins in initiation of signaling as well as the role of the small monomeric G protein, Rho, in the activation of phospholipase D. Modulation of adenylyl cyclase activity by mAChRs appears more diverse as the interaction of various receptor subtypes with the many isoforms of the enzyme are studied. Both alpha and beta subunits of G(i/o) may be involved. Some mAChR responses arise through release of nitric oxide from nitrergic nerves, including salivary gland secretion and hippocampal slow wave activity. mAChRs utilize a variety of intracellular pathways to activate various mitogen-activated protein kinases. The kinases are involved in cholinergic regulation of kidney epithelial function, catabolism of amyloid precursor protein, hippocampal long-term potentiation, activation of phospholipase A(2), and gene induction. mAChR activation can also stimulate or inhibit cellular growth and apoptosis, dependent on prior levels of cellular activity. Modulation of ion channels by mAChR agonists appears increasingly complex, based on recent studies. K(+) channels may be activated by M(2) and M(4) mAChR stimulation, although in the rat superior cervical ganglion topographical constraints appear to limit the effect to the M(2) mAChR. Another ganglionic K(+) current, the M current, is inhibited by M(1) mAChR activation, but in murine hippocampus inhibition involves another receptor subtype. R-type Ca(2+) channels are both facilitated and inhibited by M(1) and M(2) mAChRs; facilitation being more pronounced with activation of M(1) mAChRs and inhibition with M(2) mAChRs.
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Receptores Muscarínicos/metabolismo , Transducción de Señal/fisiología , Animales , Enzimas/metabolismo , Factor de Crecimiento Epidérmico/metabolismo , Proteínas de Unión al GTP/metabolismo , Humanos , Canales Iónicos/metabolismoRESUMEN
A total of 123 community paediatricians and 23 microbiology laboratories studied the clinical and bacteriological efficacy of treatment of group A streptococcal pharyngitis in Italy. Of 1065 patients, from whom Streptococcus pyogenes was isolated, 723 returned to follow up and of these 138 (19%) still had a positive throat culture. The erythromycin resistance (ER) rate was 23.7% with resistance phenotype distribution of: 31.7% constitutive (CR), 26.6% inducible (IR) and 41.7% efflux pump (M) resistance phenotype. All strains were susceptible to the beta-lactam agents tested. CR strains were highly resistant to all 14, 15 and 16 membered macrolides with the exception of rokitamycin which showed activity against 37.8% of isolates. All phenotype M and some IR isolates were susceptible to clindamycin, rokitamycin, josamycin and spiramycin; clarithromycin was active against a small percentage of strains belonging to the IR and M phenotype. Bacterial eradication was found in 85.5, 78.7 and 75.8% of the penicillin, macrolide and cephalosporin treated groups. Genotyping of strains showed that 8.7% of the 19% of cases classified as 'failed bacterial eradication' were due to recolonization with a different isolate, observed exclusively among beta-lactams treated patients. Clinical cure was achieved in a high percentage of cases, irrespective of the antibiotic prescribed, with the best clinical efficacy being found following therapy with amoxycillin and clarithromycin (90.9%).
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Antibacterianos/uso terapéutico , Faringitis/tratamiento farmacológico , Faringe/microbiología , Infecciones Estreptocócicas/tratamiento farmacológico , Streptococcus pyogenes/efectos de los fármacos , Adolescente , Antibacterianos/farmacología , Niño , Preescolar , Farmacorresistencia Microbiana , Eritromicina/farmacología , Eritromicina/uso terapéutico , Humanos , Italia , Pruebas de Sensibilidad Microbiana , Penicilinas/farmacología , Penicilinas/uso terapéutico , Faringitis/microbiología , Infecciones Estreptocócicas/microbiología , Streptococcus pyogenes/aislamiento & purificaciónRESUMEN
The effects of the muscarinic receptor antagonist, otenzepad, in combination with the competitive antagonists N-methylscopolamine, dexetimide and atropine, or the allosteric modulators, C(7)/3'-phth, gallamine and alcuronium, were measured in the guinea pig electrically driven left atrium using the agonists, carbachol or acetylcholine. Otenzepad, in combination with C(7)/3'-phth or gallamine, gave concentration-ratios close to additive and in agreement with theoretical model predictions for combination of two allosteric modulators acting at a common site. However, when otenzepad was combined with alcuronium, dexetimide or N-methylscopolamine, supra-additive effects were observed. For either competitive antagonist in combination with otenzepad, the degree of supra-additivity was more evident after 2-h equilibration than after 40 min. When otenzepad was combined with atropine, no supra-additivity was observed with carbachol as the agonist, but was evident with acetylcholine. Otenzepad was also unable to fully inhibit [3H]N-methylscopolamine binding when the radioligand was employed at a concentration of approximately 100 x K(D). It is concluded that the action of otenzepad involves an allosteric site and a number of possibilities are discussed for its location.
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Atrios Cardíacos/efectos de los fármacos , Parasimpatolíticos/farmacología , Pirenzepina/farmacología , Receptores Muscarínicos/metabolismo , Acetilcolina/farmacología , Regulación Alostérica/fisiología , Animales , Atropina/farmacología , Carbacol/farmacología , Cardiotónicos/farmacología , Dexetimida/farmacología , Estimulación Eléctrica , Femenino , Trietyoduro de Galamina/farmacología , Cobayas , Atrios Cardíacos/metabolismo , Técnicas In Vitro , Cinética , Masculino , Antagonistas Muscarínicos/farmacología , N-Metilescopolamina/farmacología , Antagonistas Nicotínicos/farmacología , Ftalimidas/farmacología , Pirenzepina/análogos & derivados , Compuestos de Amonio Cuaternario/farmacología , Ensayo de Unión Radioligante , Receptor Muscarínico M2 , Receptores Muscarínicos/químicaRESUMEN
1. An allosteric interaction occurs when the binding of a ligand to its site on a receptor is able to modify the binding of another ligand to a topographically distinct site on the same receptor and vice versa. The muscarinic cholinoceptors represent the best-studied examples of allosteric phenomena among the G-protein-coupled receptor superfamily. 2. The simplest model describing allosteric interactions at muscarinic cholinoceptors is the ternary complex model, which allows for a three-way interaction between the receptor, a classical (orthosteric) ligand and an allosteric modulator. The interaction may be quantified using the dissociation constant of each ligand for its respective binding site on the free receptor and the 'co-operativity factor' alpha. This latter term is the ratio of affinities of a ligand for the occupied versus the unoccupied receptor and is a measure of the magnitude of the cooperativity between two concomitantly bound ligands. 3. Identification of allosteric phenomena requires the utilization of both radioligand binding and functional approaches. Manifestations of allosterism include: (i) a limited ability to influence radioligand binding as the concentration of the latter is increased; (ii) alterations in the dissociation rate of orthosteric ligands; (iii) curvilinear Schild regressions; and (iv) nonadditivity of agonist/orthosteric antagonist/allosteric modulator combination concentration ratios. 4. Allosteric modulators of muscarinic cholinoceptors represent a diverse range of compounds. Some of the most studied agents include gallamine, alcuronium and the bis-ammonium compounds, C7/3'-phth and W84. Alcuronium has proven a most useful pharmacological tool, as it has been shown to display both positive and negative co-operativity, depending on the receptor subtype and orthosteric ligand involved in the interaction. 5. Evidence has accumulated pointing to the existence of a common allosteric binding site on the muscarinic cholinoceptors, located close to the orthosteric site, but at a more extracellular level. However, the possibility of more than one accessory binding site on various receptor subtypes cannot be excluded. 6. Allosteric modulators offer a number of potential therapeutic advantages, including a ceiling level to their effects and the possibility of 'absolute selectivity' of action, based on the degree of co-operativity rather than the affinity of the modulator for any one receptor subtype.
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Receptores Muscarínicos/metabolismo , Alcuronio/química , Regulación Alostérica , Compuestos de Bis-Trimetilamonio/química , Predicción , Trietyoduro de Galamina/química , Humanos , Isoindoles , Modelos Químicos , Antagonistas Muscarínicos/química , Fármacos Neuromusculares no Despolarizantes/química , Receptores Muscarínicos/químicaRESUMEN
Functional studies were conducted on guinea pig atrial muscarinic acetylcholine M2 receptors with the allosteric modulators heptane-1,7-bis(dimethyl-3'-phthalimidopropyl)ammonium bromide (C7/3'-phth), gallamine and alcuronium to determine whether these ligands are able to recognize a common accessory site. The three modulators inhibited the negative inotropic response to carbachol in this tissue. When used in combination, C7/3'-phth and gallamine or C7/3'-phth and alcuronium gave dose ratios that were either additive or underadditive. In contrast, the combinations of C7/3'-phth or alcuronium with the competitive antagonists, N-methylscopolamine or atropine, yielded supra-additive dose ratios. The data could be reconciled with a model involving a ternary complex between (1) the receptor, (2) carbachol, N-methylscopolamine or atropine acting at the orthosteric binding site and (3) C7/3'-phth, alcuronium or gallamine acting at a common, allosteric site with varying degrees of heterotropic cooperativity.
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Antagonistas Muscarínicos/farmacología , Receptores Muscarínicos/efectos de los fármacos , Alcuronio/farmacología , Regulación Alostérica , Animales , Atropina/farmacología , Femenino , Trietyoduro de Galamina/farmacología , Cobayas , Masculino , N-Metilescopolamina , Receptor Muscarínico M2 , Derivados de Escopolamina/farmacologíaRESUMEN
The effects of two competitive antagonists and two allosteric ligands on the rate of dissociation of [3H]N-methylscopolamine ([3H]NMS) were studied at atrial muscarinic acetylcholine M2 receptors by the technique of "infinite dilution." The dissociation rate for [3H]NMS, initiated by diluting the incubation mixture in a 100-fold volume of buffer, was 0.61 +/- 0.10 min-1. Addition of the competitive antagonists, atropine or NMS, to the dilution medium did not alter the observed [3H]NMS dissociation rate. In contrast, gallamine and the bisquaternary, heptane-1,7-bis-(dimethyl-3'-phthalimidopropyl-ammonium bromide) (C7/3'-phth), produced a concentration-dependent slowing of the dissociation rate of [3H]NMS, with IC50 values of 7.5 microM and 196 nM, respectively. Gallamine exhibited an increased modulatory potency when equilibration with the tissue was allowed prior to dilution. The findings showed that the influence of low concentrations of allosteric modulators on the [3H]NMS dissociation rate may be demonstrated separately from any effects on association rate, and that the contact time with the allosteric ligand may influence the extent of these effects.
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Receptores Muscarínicos/metabolismo , Regulación Alostérica , Animales , Femenino , Trietyoduro de Galamina/farmacología , Cobayas , Atrios Cardíacos/metabolismo , Cinética , Masculino , Antagonistas Muscarínicos/farmacología , N-Metilescopolamina , Receptor Muscarínico M2 , Derivados de Escopolamina/metabolismoRESUMEN
The interaction of heptane-1,7-bis(dimethyl-3'-phthalimidopropylammonium bromide) (C7/3'-phth), with several agonists, was investigated at the muscarinic M2 receptor in guinea-pig left atria. C7/3'-phth shifted concentration-response curves for the agonists, carbachol, oxotremorine-M and (+)-cis-dioxolane, to the right in a parallel fashion. Arunlakshana-Schild regressions of the data yielded slopes significantly different to unity, suggesting non-competitive antagonism. Non-linear regression analysis, using an equation based on allosteric modulation, gave quantitative estimates of co-operativity (alpha values) and the dissociation constant of C7/3'-phth (KB). In all cases, the KB estimates for C7/3'-phth were not significantly different. Increasing the carbachol contact time 10-fold did not significantly influence the KB or the alpha value obtained with C7/3'-phth. Changing from Krebs to Tyrode solution did not significantly alter the KB for C7/3'-phth, although alpha values obtained were consistently lower in Tyrode solution, suggesting that the allosteric action may be sensitive to buffer composition. A 4-fold higher degree of negative, heterotropic co-operativity between C7/3'-phth and agonists than between C7/3'-phth and competitive antagonists was also found.
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Compuestos de Bis-Trimetilamonio/farmacología , Agonistas Muscarínicos/farmacología , Antagonistas Muscarínicos/farmacología , Receptores Muscarínicos/efectos de los fármacos , Acetilcolina/metabolismo , Acetilcolina/farmacología , Animales , Unión Competitiva , Compuestos de Bis-Trimetilamonio/metabolismo , Tampones (Química) , Carbacol/metabolismo , Carbacol/farmacología , Dioxolanos/metabolismo , Dioxolanos/farmacología , Interacciones Farmacológicas , Femenino , Cobayas , Técnicas In Vitro , Isoindoles , Cinética , Masculino , Agonistas Muscarínicos/metabolismo , Antagonistas Muscarínicos/metabolismo , Oxotremorina/análogos & derivados , Oxotremorina/metabolismo , Oxotremorina/farmacología , Receptor Muscarínico M2 , Receptores Muscarínicos/metabolismoRESUMEN
The serum levels of flurithromycin ethylsuccinate achieved 30 min after a single oral dose of 375 mg were found to be equal or above the minimal inhibitory concentrations for sensitive strains, when administered to 12 healthy volunteers. The serum half-life was found to be approximately 4 h.