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Chamber Technique (chamber + technique)
Selected AbstractsFS02.8 Patch testing with gold trichloride can give false test resultsCONTACT DERMATITIS, Issue 3 2004Birgitta Gruvberger Background:, Hydrochloric acid is formed in water solutions of gold trichloride. Hydrochloric acid in contact with aluminium generates hydrogen gas which can reduce and transform trivalent gold to elemental gold. Objective:, To investigate whether patch testing with aqueous gold trichloride can cause false positive (irritant) reactions in patients without contact allergy to gold and false negative reactions in patients with gold allergy. Methods:, 13 patients with and 13 patients without positive patch test reactions to gold sodium thiosulfate were tested with gold trichloride in 2 different vehicles, water and alkaline buffer, using 2 different test techniques, the Finn Chamber technique with aluminium chambers and van der Bend technique with polypropene chambers. Results:, Irritant patch test reactions were obtained with aqueous gold trichloride tested in van der Bend chambers in 10 patients without gold allergy. In gold-allergic patients no positive test reactions were obtained from aqueous gold trichloride in Finn chambers while 2 positive test reactions were obtained from gold trichloride in alkaline buffer tested in van der Bend chambers. Conclusion:, If gold trichloride is patch tested in wrong vehicle and with wrong test technique irritant test reactions may occur which can be misinterpreted as positive allergic reactions in patients without gold allergy as well as negative reactions in patients with gold allergy. [source] The atmospheric oxidation of ethyl formate and ethyl acetate over a range of temperatures and oxygen partial pressuresINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 7 2010John J. Orlando The Cl-atom-initiated oxidation of two esters, ethyl formate [HC(O)OCH2CH3] and ethyl acetate [CH3C(O)OCH2CH3], has been studied at pressures close to 1 atm as a function of temperature (249,325 K) and O2 partial pressure (50,700 Torr), using an environmental chamber technique. In both cases, Cl-atom attack at the CH2 group is most important, leading in part to the formation of radicals of the type RC(O)OCH(O,)CH3 [R = H, CH3]. The atmospheric fate of these radicals involves competition between reaction with O2 to produce an anhydride compound, RC(O)OC(O)CH3, and the so-called ,-ester rearrangement that produces an organic acid, RC(O)OH, and an acetyl radical, CH3C(O). For both species studied, the ,-ester rearrangement is found to dominate in air at 1 atm and 298 K. Barriers to the rearrangement of 7.7 ± 1.5 and 8.4 ± 1.5 kcal/mole are estimated for CH3C(O)OCH(O,)CH3 and HC(O)OCH(O,)CH3, respectively, leading to increased occurrence of the O2 reaction at reduced temperature. The data are combined with those obtained from similar studies of other simple esters to provide a correlation between the rate of occurrence of the ,-ester rearrangement and the structure of the reacting radical. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 397,413, 2010 [source] Influence of deoxynivalenol on the D -glucose transport across the isolated epithelium of different intestinal segments of laying hensJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5-6 2007W. A. Awad Summary Deoxynivalenol (DON) decreases glucose absorption in the proximal jejunum of laying hens in vitro and this effect is apparently mediated by the inhibition of the sodium d -glucose co-transporter. DON could modulate the sugar transport of other intestinal regions of chickens. For this purpose, we have measured the effects of DON on the Na+d -glucose co-transporter, by addition of DON after and before a glucose addition in the isolated epithelium from chicken duodenum, jejunum, ileum, caecum and colon by using the Ussing chamber technique in the voltage clamp technique. The data showed in all segments of the gut that the addition of d -glucose on the mucosal side produced an increase in the current (Isc) compared with the basal values, the Isc after glucose addition to the small intestine was greater than the Isc of the large intestine compared with the basal values, specially of the jejunum (p < 0.002), indicating that the jejunum is the segment that is the best prepared for Na+ - d -glucose co-transport. Further addition of 10 ,g DON/ml to the mucosal solution decreased the Isc in all segments and the Isc returned to the basal value, especially in the duodenum and mid jejunum (p < 0.05). In contrast, the addition of 5 mmol d -glucose/l on the mucosal side after incubation of the tissues with DON in all segments had no effect on the Isc (p > 0.05), suggesting that DON previously inhibited the Na+d -glucose co-transport. The blocking effects of DON in duodenum and jejunum were greater than the other regions of the gut. It can be concluded that the small intestine of laying hens has the most relevant role in the carrier mediated glucose transport and the large intestine, having non-significant capacity to transport sugars, appears to offer a minor contribution to glucose transport because the surface area is small. The effect of d -glucose on the Isc was reversed by DON in all segments, especially in the duodenum and jejunum, suggesting that DON entirely inhibited Na+ - d -glucose co-transport. This finding indicates that the inhibition of Na+ co-transport system in all segments could be an important mode of action for DON toxicity of hens. Zusammenfassung Deoxynivalenol (DON) erniedrigt in vitro die Glukoseabsorption im proximalen Jejunum von Legehennen. Dieser Effekt ist vermutlich durch eine Hemmung des Natrium- d -Glukose-Cotransportsystems bedingt. DON könnte außerdem den Glukosetransport in anderen Segmenten des Darms beeinflußen. Zu diesem Zweck haben wir Wirkungen von DON auf das Natrium- d -Glukose-Cotransportsystem gemessen, indem wir DON nach und vor einer Glukosezugabe auf isolierte Darmepithelien des Duodenums, Jejunums, Ileums, Caecums und des Kolons mittels der Ussing-Kammer-Technik in der Volt-Klemmtechnik einwirken ließen. Die erzielten Daten wiesen in allen Segmenten des Darms verglichen mit den Basalwerten einen Anstieg im Strom (Isc) auf, wobei die Isc des Dünndarms bei Glukosegabe signifikant größer als die des Dickdarms waren, was darauf hinweist, dass das Jejunum am besten für den Glukosetransport geeignet war. Eine DON-Zugabe von 10 ,g/ml zur mukosalen Lösung schwächte den Isc in allen Segmenten, wobei die Isc speziell im Duodenum und mittleren Jejunum zum Ausgangswert zurück kehrten. Im Gegensatz dazu brachte die mukosale Glukosezugabe nach der DON-Inkubation keinen signifikanten Anstieg der Isc (p > 0,05), was auf eine durch DON hervorgerufene Blockade des Natrium- d -Glukose-Cotransportsystems schließen ließ. Es kann daraus geschlossen werden, dass der Dünndarm von Legehennen den bedeutendsten Einfluß im Glukosetransportmechanismus nimmt und der Dickdarm aufgrund einer kleineren Oberfläche einen geringeren Beitrag zum Glukosetransport leistet. Dem Isc steigernden Effekt der Glukose konnte signifikant durch DON in den Darmsegmenten besonders im Duodenum und im Jejunum entgegen gewirkt werden, was auf eine umfassende Hemmung des Natrium- d -Glukose-Cotransportsystems hinweist. Die Resultate weisen darauf hin, dass eine Hemmung des Natrium- d -Glukose-Cotransportsystems in allen Darmsegmenten eine wichtige Rolle in der DON-Toxizität für die Henne darstellen könnte. [source] Substance P receptor antagonist reverses intestinal pathophysiological alterations occurring in a novel ex-vivo model of Cryptosporidium parvum infection of intestinal tissues derived from SIV-infected macaquesJOURNAL OF MEDICAL PRIMATOLOGY, Issue 3 2008A. Garza Abstract Background,Cryptosporidium infection leads to life-threatening diarrhea in AIDS patients. Pathogenesis of cryptosporidiosis is due to intestinal physiological alterations. We devised an ex-vivo model using ex-vivo Cryptosporidium parvum infection of jejunal tissues derived from SIV-infected macaques and studied the role of substance P (SP) in the pathogenesis of cryptosporidiosis. Methods, We measured jejunal SP protein levels using ELISA, and electrophysiological alterations using the Ussing chamber technique in an ex vivo model of Cryptosporidium infection. Paraformaldehyde-fixed jejunum from SIV-infected macaques with and without naturally occurring cryptosporidiosis was studied for SP protein expression by immunohistochemistry and fluorescence deconvolution microscopy. Results,Ex-vivo Cryptosporidium -infected tissues and tissues from SIV-infected macaques with naturally occurring cryptosporidiosis demonstrated elevated SP protein levels compared with tissues from SIV-infected animals without ex-vivo C. parvum infection or tissues from SIV-infected animals that have no evidence of cryptosporidiosis. In our ex-vivo model of Cryptosporidium infection, we demonstrated pathophysiological alterations that were blocked by SP-receptor antagonist treatment. Conclusions, These studies suggest that SP-receptor antagonists could prove useful for treatment of AIDS-related cryptosporidiosis. [source] Comparison of relaxation responses to multiple vasodilators in TxA2 -analog and endothelin-1-precontracted pulmonary arteriesACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2007C. Piamsomboon Background:, Peri-operative pulmonary hypertension can lead to right ventricular dysfunction and to an increase in morbidity and mortality. Altered function of the pulmonary vascular endothelium and vasoconstriction play a crucial role in the development of elevated pulmonary vascular resistance. Because pulmonary artery vasoreactivity is dependent on many factors including the constricting agent that precipitated the event therefore the aim of the current study was to investigate the effectiveness of different classes of vasodilator agents to reverse endothelin-1 (ET-1) or thromboxane A2 (TxA2)-induced vasoconstriction in porcine pulmonary artery (PA) in vitro. Methods:, Relaxation responses to vasodilatory drugs were studied in PA precontracted with ET-1 (1 × 10,8 M) or TxA2 analog (U46619, 1 × 10,8 M). All vasodilating drugs were added in a cumulative fashion and isometric tension measurements were obtained using an organ chamber technique. Results:, In both groups relaxation responses to the vasodilators were dose dependent. When ET-1 was used as a constrictor nitroglycerin and milrinone caused nearly complete (80,100%) relaxation, whereas other agents were of limited effectiveness (40,50%). On the other hand, in the vessels constricted with U46619, olprinone, indomethacin, prostaglandin E1 (PGE1), nitroglycerin, milrinone and clevidipine induced complete (90,110%) vasodilatation but brain natriuretic peptide (BNP), l -arginine, and isoproterenol relaxed the vessels maximally by 45,60%. Conclusions:, Nitroglycerin and milrinone are very effective in reversing ET-1 and U46619-induced pulmonary vasoconstriction in vitro. The effectiveness of other drugs studied was dependent on the type of constrictor used. BNP, l -arginine and isoproterenol were shown to have minimal vasodilatory effects in porcine PA. [source] Static Magnetic Fields Affect Capillary Flow of Red Blood Cells in Striated Skin MuscleMICROCIRCULATION, Issue 1 2008Gunnar Brix ABSTRACT Blood flowing in microvessels is one possible site of action of static magnetic fields (SMFs). We evaluated SMF effects on capillary flow of red blood cells (RBCs) in unanesthetized hamsters, using a skinfold chamber technique for intravital fluorescence microscopy. By this approach, capillary RBC velocities (vRBC), capillary diameters (D), arteriolar diameters (Dart), and functional vessel densities (FVD) were measured in striated skin muscle at different magnetic flux densities. Exposure above a threshold level of about 500 mT resulted in a significant (P < 0.001) reduction of vRBC in capillaries as compared to the baseline value. At the maximum field strength of 587 mT, vRBC was reduced by more than 40%. Flow reduction was reversible when the field strength was decreased below the threshold level. In contrast, mean values determined at different exposure levels for the parameters D, Dart, and FVD did not vary by more than 5%. Blood flow through capillary networks is affected by strong SMFs directed perpendicular to the vessels. Since the influence of SMFs on blood flow in microvessels directed parallel to the field as well as on collateral blood supply could not be studied, our findings should be carefully interpreted with respect to the setting of safety guidelines. [source] Assessment of inhalation technique and determinants of incorrect performance among children with asthmaPEDIATRIC PULMONOLOGY, Issue 11 2006Mandeep Walia MD Abstract The objective of our study was to evaluate the pressurized metered dose inhaler (pMDI) with holding chamber technique of asthmatic children attending out patient pediatric chest clinic and determine factors associated with incorrect technique. All patients had previously received instructions regarding inhalation technique. The inhalation technique was assessed on a five-point checklist, four of which were considered essential. Two hundred and thirteen children (mean,±,SD age, 7.3,±,3.8 years; 151 boys) completed the study. Children were using their inhaler for a median duration of 6 months (range 1,96 months). One hundred and eighty-eight patients (88.3%) performed all essential steps correctly. The commonest mistake among the essential steps was not shaking the inhaler (n,=,21, 9.9%) followed by inability to make a tight seal around the mouthpiece of the holding chamber (n,=,12, 5.6%). Correct technique was not affected by gender, asthma severity and socio-economic indices: education level of parents, percapita monthly income, rural or urban background. Our study indicates that a large majority of children from a developing country setting, irrespective of lower education and income levels can be successfully educated to appropriately use inhalation device. Inhalation performance is not affected by socio-economic background of the patients. Comprehensive inhalation instructions and monitoring at each visit are however critical to ensure reliable and consistent performance of correct technique among asthmatic children. Pediatr Pulmonol. 2006, 41:1082,1087. © 2006 Wiley-Liss, Inc. [source] Baroreflex Sensitivity: Measurement and Clinical ImplicationsANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2008Maria Teresa La Rovere M.D. Alterations of the baroreceptor-heart rate reflex (baroreflex sensitivity, BRS) contribute to the reciprocal reduction of parasympathetic activity and increase of sympathetic activity that accompany the development and progression of cardiovascular diseases. Therefore, the measurement of the baroreflex is a source of valuable information in the clinical management of cardiac disease patients, particularly in risk stratification. This article briefly recalls the pathophysiological background of baroreflex control, and reviews the most relevant methods that have been developed so far for the measurement of BRS. They include three "classic" methods: (i) the use of vasoactive drugs, particularly the ,-adrenoreceptor agonist phenylephrine, (ii) the Valsalva maneuver, which produces a natural challenge for the baroreceptors by voluntarily increasing intrathoracic and abdominal pressure through straining, and (iii) the neck chamber technique, which allows a selective activation/deactivation of carotid baroreceptors by application of a negative/positive pressure to the neck region. Two more recent methods based on the analysis of spontaneous oscillations of systolic arterial pressure and RR interval are also reviewed: (i) the sequence method, which analyzes the relationship between increasing/decreasing ramps of blood pressure and related increasing/decreasing changes in RR interval through linear regression, and (ii) spectral methods, which assess the relationship (in terms of gain) between specific oscillatory components of the two signals. The limitations of the coherence criterion for the computation of spectral BRS are discussed, and recent proposals for overcoming them are presented. Most relevant clinical applications of BRS measurement are finally reviewed with particular reference to patients with myocardial infarction and heart failure. [source] Selective priming of peripheral blood eosinophils in patients with idiopathic hypereosinophilic syndrome,APMIS, Issue 11 2006MARIA LAMPINEN The idiopathic hypereosinophilic syndrome (HES) is characterised by blood eosinophilia associated with organ involvement. Elevated numbers of blood neutrophils have been observed during episodes of active HES. However, an increased responsiveness of eosinophils to chemotactic and chemokinetic stimuli may explain the selective eosinophil infiltration of the tissue. We have studied the migratory responses of blood eosinophils and neutrophils from 9 patients with HES and from 13 healthy control subjects. Chemokinetic and chemotactic responses to factors acting on both cell types were analysed by means of a modification of the Boyden chamber technique. We found increased migratory responses of the eosinophils, but not of the neutrophils, from the patients with HES. Increased blood neutrophil counts in three of the patients did not coincide with alterations of the neutrophil migratory responses. Our finding of increased migratory responses of eosinophils from patients with HES towards non-specific chemoattractants suggests selective priming of eosinophils in this disease. Interleukin (IL)-5 has previously been shown to prime eosinophils for migratory responses, and successful anti-IL-5 therapy of patients with HES indicates an important role for this cytokine in the development of hypereosinophilia. [source] | ||||||||||