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Mean Peak (mean + peak)
Selected AbstractsStatistical criteria to establish optimal antibody dilution in flow cytometry analysisCYTOMETRY, Issue 3 2007Cesar J. G. Collino Abstract Background: In direct techniques of flow cytometry, the optimal antibody dilution or titer point is established from the plateau area of the antibody titration curve. However, the plateau area is defined without any statistical criteria, which may lead to an incorrect selection of antibody dilution. Herein, we report statistical criteria to establish the optimal antibody dilution for CD14, CD8, CD4, and CD3 analysis by flow cytometry in peripheral whole blood. Methods: The unpaired t- test (two-tail P value) was used as statistical criteria to analyze the titration curve of the following monoclonal antibody panels: CD14-FITC, CD8-FITC, CD4-RD1, and CD3-PC5. Results: Using the unpaired t- test (two-tail P value), the plateau area from the antibody titration curve was fitted when two consecutive antibody volumes showed mean peak of channel fluorescence (MPCF) values not significantly different. When the antibody was used at volume corresponding to that of the antibody titration point, the flow cytometry analysis of whole blood samples with different density of cell antigens can be correctly discriminated. Conclusion: This statistical criteria allows the fitting of the plateau area of MPCF versus antibody volume and consequently, to define the optimal antibody dilution. © 2007 Clinical Cytometry Society [source] Acute Stress Hyperglycemia in Cats Is Associated with Struggling and Increased Concentrations of Lactate and NorepinephrineJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 2 2002Jacqueline S. Rand We characterized the changes in blood glucose concentrations in healthy cats exposed to a short stressor and determined the associations between glucose concentrations, behavioral indicators of stress, and blood variables implicated in stress hyperglycemia (plasma glucose, lactate, insulin, glucagon, cortisol, epinephrine, and norepinephrine concentrations). Twenty healthy adult cats with normal glucose tolerance had a 5-minute spray bath. Struggling and vocalization were the most frequent behavioral responses. There was a strong relationship between struggling and concentrations of glucose and lactate. Glucose and lactate concentrations increased rapidly and significantly in all cats in response to bathing, with peak concentrations occurring at the end of the bath (glucose baseline 83 mg/dL, mean peak 162 mg/dL; lactate baseline 6.3 mg/dL, mean peak 64.0 mg/dL). Glucose response resolved within 90 minutes in 12 of the 20 cats. Changes in mean glucose concentrations were strongly correlated with changes in mean lactate (r= .84; P <.001) and mean norepinephrine concentrations (r= .81; P < .001). There was no significant correlation between changes in mean glucose concentrations and changes in mean insulin, glucagon, cortisol, or epinephrine concentrations. Struggling and lactate concentrations were predictive of hyperglycemia. Gluconeogenesis stimulated by lactate release is the likely mechanism for hyperglycemia in healthy cats in this model of acute stress. Careful handling techniques that minimize struggling associated with blood collection may reduce the incidence of stress hyperglycemia in cats. [source] "Tuned" Defibrillation Waveforms Outperform 50/50% Tilt Defibrillation Waveforms: A Randomized Multi-Center StudyPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2007SENTHIL NATARAJAN M.D. Introduction: A superior performance of a tuned waveform based on duration using an assumed cardiac membrane time constant of 3.5 ms and of a 50/50% tilt waveform over a standard 65/65% tilt waveform has been documented before. However, there has been no direct comparison of the tuned versus the 50/50% tilt waveforms. Methods: In 34 patients, defibrillation thresholds (DFTs) for tuned versus 50/50% tilt waveforms in a random order were measured by using the optimized binary search method. High voltage lead impedance was measured and used to select the pulse widths for tuned and 50/50% tilt defibrillation waveforms. Results: Delivered energy (7.3 ± 4.6 J vs 8.7 ± 5.3 J, P = 0.01), stored energy (8.2 ± 5.1 J vs 9.7 ± 5.6 J, P = 0.01), and delivered voltage (405.9 ± 121.7 V vs 445.0 ± 122.6 V, P = 0.008) were significantly lower for the tuned than for the 50/50% tilt waveform. In four patients with DFT ,15 J, the tuned waveform lowered the mean energy DFT by 2.8 J and mean voltage DFT by 45 V. For all patients, the mean peak delivered energy DFT was reduced from 29 J to 22 J (24% decrease). Multiple regression analysis showed that a left ventricular ejection fraction <20% is a significant predictor of this advantage. Conclusion: Energy and voltage DFTs are lowered with an implantable cardioverter defibrillator that uses a tuned waveform compared to a standard 50% tilt biphasic waveform. [source] Cellular responses to Loa loa experimental infection in mandrills (Mandrillus sphinx) vaccinated with irradiated infective larvaePARASITE IMMUNOLOGY, Issue 4 2000Ungeheuer In order to shed light on the mechanisms of antifilarial protective immunity, we investigated the course of experimental loaiosis after vaccination in a nonhuman primate host, Mandrillus sphinx. Six vaccinated (V) mandrills received 50 irradiated L3 while six nonvaccinated (NV) received saline solution on days ,60, ,30 and ,15. All animals were challenged with 100 intact L3 (day 0). Parasitological and immunological status were followed for 9 months. Vaccination delayed the appearance and mean peak of microfilaraemia. Five mandrills (Mf,) were never microfilaraemic (one V mandrill) or microfilaraemic on only one occasion (2 V and 2 NV), the other seven having stable microfilaraemia (Mf+). The cytokine response of peripheral blood mononuclear cells to L3 (L3 Ag) was Th2 dominated, while microfilariae (Mf Ag) elicited a Th0-like response. During vaccination, Th2 cytokine production significantly increased in V mandrills against L3 Ag, as well as Mf Ag, whereas Th1 cytokines decreased. On day 60 postinoculation, cellular proliferation was higher in V mandrills in response to L3 and Mf Ags and PHA-L mitogen. At the end of prepatency (on day 130), mandrills with delayed appearance of microfilaraemia exhibited a high, transient IL-2 and IL-4 secretion in response to L3 Ag. Finally, high anti-Mf Th2 cytokine levels characterized Mf,mandrills not only during prepatency, but also (for IL-5) before immunization. However, the presence of a balanced Th1 anti-L3 response during prepatency in the amicrofilaraemic mandrill suggests its importance in protective immunity. Taken together, our data suggest that Th2 cells and also Th1 components of the antifilarial response, especially to larval antigen, may contribute to parasite elimination. [source] | ||||||||||