Home About us Contact
|
Home About us Contact | ||
|
|
||
Dilution
Kinds of Dilution Terms modified by Dilution Selected AbstractsUSE OF LITHIUM DILUTION AND PULSE CONTOUR ANALYSIS CARDIAC OUTPUT DETERMINATION IN ANAESTHETISED HORSES , A CLINICAL EVALUATIONJOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue S1 2004Gayle D Hallowell Pulse contour analysis is a relatively new method of continuously monitoring cardiac output. The objective of this study was to evaluate the suitability of the human algorithm for calculation of continuous cardiac output from the pulse waveform, for use in anaesthetised horses. Cardiac output was measured in 27 anaesthetised clinical cases comparing lithium dilution (LiDCO) with a preceding, calibrated cardiac output measured from the pulse waveform (PulseCO) using a commercial system (LiDCOplus, LiDCO Ltd., Cambridge, UK). These comparisons were repeated every 20,30 min. Positive inotropes or vasopressors were administered when clinically indicated. Cardiac output values obtained ranged from 15.2,52.2 L/min, with cardiac indices from 30.7,114.9 ml/kg/min. Eighty-nine comparisons were obtained. The mean bias was 0.24 ml/kg/min +/,6.48 ml/kg/min. The limits of agreement were ,12.72,13.2 ml/kg/min. The 95% confidence interval for the upper limit of agreement was 12.07,14.33 ml/kg/min and for the lower limit of agreement was ,11.59,13.85 ml/kg/min. Linear regression analysis demonstrated a correlation coefficient (r2) of 0.89 and produced an equation of PulseCO (mls kg,1 minute,1)=0.9226LiDCO (mls kg,1minute,1) +5.354. This method of pulse contour analysis is a relatively non-invasive and reliable way of monitoring continuous cardiac output in the horse under anaesthesia. The ability to easily continuously monitor cardiac output may improve morbidity and mortality in the anaesthetised horse. [source] The Explanatory Power of Canadian Accounting Measures of Earnings Dilution,ACCOUNTING PERSPECTIVES, Issue 1 2002THOMAS W. SCOTT ABSTRACT This paper examines the properties of the accounting measures of dilution under pre-2001 Canadian GAAP. Fully diluted earnings per share (EPS) presents investors with a per-share figure that attempts to capture the maximum potential dilution that would occur if all dilutive convertible securities were converted and all dilutive stock options and rights exercised. We examine how the difference between basic and fully diluted EPS, which we refer to as the dilutive adjustment, affects the ability of EPS to predict one-period-ahead EPS. Moreover, we address the issue of the explanatory power of changes in the dilutive adjustment for unexpected stock returns over the year and at the earnings announcement date. Surprisingly, in contrast with the traditional accounting view that increases in the dilutive adjustment present the investor with bad news due to potential dilution of the future earnings stream, the dilutive adjustment is positively related to next period's earnings and increases in the dilutive adjustment are positively correlated with contemporaneous long-window stock returns. These results can be attributed to the relation between the dilutive adjustment and the earnings process combined with a partial resolution of the uncertainty attached to growth firms. We find no evidence that investors use information from the disclosure of fully diluted EPS at the earnings announcement date. These results are consistent with increases in the dilutive adjustment capturing the partial realization of a firm's growth potential that more than outweighs the potential dilution attached to the convertible securities; however, this information appears to be already embedded in price prior to the disclosure of fully diluted EPS. [source] Studies on BrdU labeling of hematopoietic cells: Stem cells and cell linesJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2003Lizhen Pang Studies using chronic in vivo BrdU exposure, isolating primitive stem cells, and determining BrdU labeling, indicate that stem cells cycle. BrdU is also incorporated into DNA during damage/repair. DNA, which has incorporated BrdU due to cycle transit is heavier than normal, while the density of DNA with damage/repair incorporation is intermediate. DNA density of purified lineage,rhodamine low (rholow) Hoechst low (Holow) stem cells or FDC-P1 cell line cells,was assessed in vitro, after exposure to cytokines and BrdU (cycling model) or cytokines and BrdU with bleomycin to induce strand breaks and hydroxyurea to halt cycle progression (damage/repair model). We determined DNA density using cesium chloride (CsCl) gradients and either fluorometry or dot blot chemiluminesence. DNA from BrdU labeled cycling Lin-rholoHolo or FDC-P1 cells was heavier than normal DNA, while damage repair DNA had an intermediate density. We then assessed BrdU labeling of Lin-rholoHolo cells in vivo. We found that 70.9% of lin-rholoHolo cells labeled at 5 weeks. DNA density of these cells was low, in the damage/repair range, but similar results were obtained with stem cells, which had proliferated in vivo. Dilution of BrdU in in vitro culture of proliferating FDC-P1 cells also resulted in damage/repair density. We conclude that in vitro BrdU labeling models can distinguish between proliferation and damage/repair, but that we cannot obtain high enough in vivo levels to address this issue. All together, while we cannot absolutely exclude damage/repair as contributing to stem cell BrdU labeling, the data indicate that primitive bone marrow stem cells are probably a cycling population. J. Cell. Physiol. 197: 251,260, 2003© 2003 Wiley-Liss, Inc. [source] Comparison of immunoradiometric assays for determination of thyroglobulin: a validation studyJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2007L.A. Tortajada-Genaro Abstract In this study we compared and validated commercial immunoradiometric assays (IRMA) to determine thyroglobulin (Tg) levels in serum. From a set of 440 samples, 68 were selected to calculate the validation parameters and the clinical performance of the assays. The commercial kits evaluated were the Tg-CTK (DiaSorin), IRMAZenco Tg (ZenTech), and SELco-Tg (Medipan). We found that 21% of the collected samples were in the critical range of concentration. Detection limits were calculated as being below 3,µg/L. Intra- and inter-reproducibility were lower than 3.1% and 9.2%, respectively. Dilution and recovery studies provided quantitative determinations. Correlation regression coefficients from the results of the methods were obtained. The determined concentrations were compared with the clinical evidence of disease. Variation in the 125-iodine-labeled antibody concentration and control charts showed the robustness of the methods. Analysis time and the simplicity of the methods were also evaluated. Reliable Tg determination is important for monitoring patients with differentiated thyroid cancer (DTC), controlling other thyroid diseases, and assessing the quality of imaging techniques. A strategy for verification and comparison based on analytical parameters and clinical performance is proposed. J. Clin. Lab. Anal. 21:147,153, 2007. © 2007 Wiley-Liss, Inc. [source] Inhibitory effect of osmotic concentration, potassium and pH on motility of the sperm of the North American burbot Lota lota maculosaJOURNAL OF FISH BIOLOGY, Issue 1 2007M. D. Zuccarelli Seminal plasma factors maintaining North American (NA) burbot Lota lota maculosa sperm quiescent were examined. Sperm were diluted into buffered saline solutions of various compositions and motility assessed. After 1 h in these solutions at 10° C, aliquots of the suspension were diluted with tap water and motility again assessed. Dilution of sperm in an incubation solution containing Ca2+ in the absence of K+ initiated sperm motility resulting in low motility when sperm were subsequently diluted in tap water. Incubation solutions with osmolalities >200 mOsm kg,1 and containing 12·5 mM K+ prevented the onset of sperm motility and were associated with maximal sperm motility upon dilution in tap water. Sperm maintained at lower osmolalities exhibited limited motility upon dilution in tap water indicating interdependence between K+ and osmolality in maintaining sperm quiescent in the presence of Ca2+. Sperm kept in incubation solution at pH values < c. 7·5 for 1 h demonstrated reduced motility when subsequently diluted in tap water. That motility of sperm was pH sensitive was further indicated by CO2 inhibition of motility. Therefore, NA burbot sperm are probably maintained in an immotile state, yet with potential for motility, by combination of high K+, osmolality and possibly pH. The results from this study differ from published information on sperm quiescence in the temporally and geographically distinct Eurasian burbot Lota lota lota. [source] Whole-blood aggregometry: are there any limits with regard to platelet counts?ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2009A. M. MENGISTU Background: Whole-blood aggregometry (WBA) is a promising tool to assess platelet function in its physiological environment. Dilution of whole blood in WBA disregards platelet concentrations that may impact the results, especially in the case of low platelet counts. In a blinded, prospective in vitro study, the influence of platelet concentrations on WBA was assessed. Methods: Aggregation studies were carried out using whole blood from 10 healthy volunteers adjusted to platelet concentrations of 150, 100, 75, 50 and 25/nl using a plasma-balanced crystalloid solution. Platelet aggregation was measured by a new near-side whole blood aggregometer, activated by adenosin-diphosphate, collagen and thrombin-receptor activating protein. Three different approaches were applied: P1: whole blood diluted by an isotonic saline solution before activation, P2: undiluted whole blood with the single and P3: with the twofold concentration of the stimulating agent. Results: Aggregometry in diluted whole blood (P1) decreased significantly from a platelet concentration of 100/nl (P<0.01). In undiluted whole blood, aggregation declined significantly from concentrations of 75 and 50/nl for P2 and P3 (P<0.01). No correlation to platelet count occurred in the undiluted approaches until a platelet concentration of 75/nl, whereas correlation in the diluted test run was detected starting from 100/nl. Conclusions: This study demonstrates that WBA depends on the platelet count and sensitivity towards low platelet concentrations may be improved by abdication of further dilution and the use of undiluted whole blood. [source] Biorelevant dissolution media: Aggregation of amphiphiles and solubility of estradiolJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2006David Ilardia-Arana Abstract Biorelevant dissolution media containing bile salt and lecithin at concentrations appropriate for fed and fasted state are useful when testing oral solid formulations of poorly water-soluble drugs. Dilution of amphiphile solutions affects the aggregation state of the amphiphiles because bile salt is partitioned between the aqueous phase and the aggregates. The aim of the investigation was to study the effect of dilution on the size distribution of aggregates and its effect on the solubilization capacity. Clear buffered solutions of four intestinal amphiphiles (sodium glycocholate, lecithin, monoolein, and oleic acid) and a combination of these were prepared at high bile salt concentration. Micelles in the glycocholate solutions decreased in size when diluted. The addition of insoluble amphiphiles led to bigger micelles with no clear correlation between size of the micelles and amphiphile concentration. Dilution of the two- and four component media caused enlargement of the mixed micelles and formation of vesicles. The solubility of estradiol in the buffer solution was increased with addition of the amphiphiles. A good correlation (R2,=,0.987) was found between estradiol solubility and mass concentration of the amphiphiles. The results demonstrate that, in the case of estradiol, the concentration of amphiphiles rather than the aggregation state determines the solubilization capacity of the medium. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:248,255, 2006 [source] Critical role of ADP interaction with P2Y12 receptor in the maintenance of ,IIb,3 activation: association with Rap1B activationJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 6 2006T. KAMAE Summary.,Objective:,Platelet integrin ,IIb,3 plays a crucial role in platelet aggregation, and the affinity of ,IIb,3 for fibrinogen is dynamically regulated. Employing modified ligand-binding assays, we analyzed the mechanism by which ,IIb,3 maintains its high-affinity state. Methods and results:,Washed platelets adjusted to 50 × 103 ,L,1 were stimulated with 0.2 U mL,1 thrombin or 5 ,m U46619 under static conditions. After the completion of ,IIb,3 activation and granule secretion, different kinds of antagonists were added to the activated platelets. The activated ,IIb,3 was then detected by fluorescein isothiocyanate (FITC)-labeled PAC1. The addition of 1 ,m AR-C69931MX (a P2Y12 antagonist) or 1 mm A3P5P (a P2Y1 antagonist) disrupted the sustained ,IIb,3 activation by ,92% and ,38%, respectively, without inhibiting CD62P or CD63 expression. Dilution of the platelet preparation to 500 ,L,1 also disrupted the sustained ,IIb,3 activation, and the disruption by such dilution was abrogated by the addition of exogenous adenosine 5,-diphosphate (ADP) in a dose-dependent fashion. The amounts of ADP released from activated platelets determined by high-performance liquid chromatography were compatible with the amounts of exogenous ADP required for the restoration. We next examined the effects of antagonists on protein kinase C (PKC) and Rap1B activation induced by 0.2 U mL,1 thrombin. Thrombin induced long-lasting PKC and Rap1B activation. AR-C69931MX markedly inhibited Rap1B activation without inhibiting PKC activation. Conclusions:,Our data indicate that the continuous interaction between released ADP and P2Y12 is critical for the maintenance of ,IIb,3 activation. [source] Colloids decrease clot propagation and strength: role of factor XIII-fibrin polymer and thrombin,fibrinogen interactionsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2005V. G. Nielsen Colloid-mediated hypocoagulability is clinically important, but the mechanisms responsible for coagulopathy have been incompletely defined. Thus, my goal was to elucidate how colloids decrease plasma coagulation function. Plasma was diluted 0% or 40% with 0.9% NaCl, three different hydroxyethyl starches (HES, mean molecular weight 450, 220 or 130 kDa), or 5% human albumin. Samples (n = 6 per condition) were activated with celite, and diluted samples had either no additions or addition of fibrinogen (FI), thrombin (FIIa) or activated Factor XIII (FXIIIa) to restore protein function to prediluted values. Thrombelastographic variables measured included clot propagation (angle, ,), and clot strength (amplitude, A; or shear elastic modulus, G). Dilution with 0.9% NaCl significantly decreased ,, A and G -values compared to undiluted samples. Supplementation with FI, but not FIIa or FXIIIa, resulted in 0.9% NaCl-diluted thrombelastographic variable values not different from those of undiluted samples. FI supplementation of HES 450, HES 220, HES 130 and albumin-diluted samples only partially restored ,, A and G -values compared to undiluted samples. FIIa addition only improved clot propagation and strength in albumin-diluted samples. FXIIIa supplementation improved propagation in samples diluted with HES 450, HES 220 and albumin, and clot strength improved in HES 450 and albumin-diluted plasma. Considered as a whole, these data support compromise of FIIa-FI and FXIIIa , fibrin polymer interactions as the mechanisms by which colloids compromise plasma coagulation. Investigation to determine if clinical enhancement of FXIII activity and/or FI concentration (e.g. fresh-frozen plasma, cryoprecipitate) can attenuate colloid-mediated decreases in hemostasis is warranted. [source] The effects of nutritional imbalance on compensatory feeding for cellulose-mediated dietary dilution in a generalist caterpillarPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2004Kwang Pum Lee Abstract. The interactive effects of macronutrient balance [protein (P) : carbohydrate (C) ratio] and dietary dilution by cellulose on nutritional regulation and performance were investigated in the generalist caterpillar Spodoptera littoralis (Boisduval). Caterpillars were reared through the final stadium on one of 20 foods varying factorially in macronutrient content (P + C%: 42, 33.6. 25.2 or 16.8%) and P : C ratio (5 : 1, 2 : 1, 1 : 1, 1 : 2 or 1 : 5). The animals compensate by eating more of diluted foods, but suffer reduced nutrient intake in proportion to the degree of dilution. Increase in food intake with dilution is greater on balanced than imbalanced foods and this is reflected in greater reduction of dry pupal mass with dilution in the latter. Whereas dilution results in a reduction in the amount of whichever macronutrient is in excess in the food, by contrast, the ability to compensate for the deficient macronutrient in the food is unaffected by nutrient imbalance. Excess protein intake due to nutritional imbalance (diets with high P : C ratios) results in a regulatory decrease in the efficiency of retention of ingested nitrogen relative to restricted protein intake on oppositely imbalanced foods (low P : C ratios). By contrast, decreased protein intake due to dietary dilution is associated with a non-regulatory reduction in the efficiency of retention, irrespective of P : C ratio. Dilution is similarly associated with reduced utilization efficiency of ingested carbohydrate. The ecological implications of these results are discussed. [source] Structural and functional organization of Complex I in the mitochondrial respiratory chainBIOFACTORS, Issue 1-4 2003Cristina Bianchi Abstract Metabolic flux control analysis of NADH oxidation in bovine heart submitochondrial particles revealed high flux control coefficients for both Complex I and Complex III, suggesting that the two enzymes are functionally associated as a single enzyme, with channelling of the common substrate, Coenzyme Q. This is in contrast with the more accepted view of a mobile diffusable Coenzyme Q pool between these enzymes. Dilution with phospholipids of a mitochondrial fraction enriched in Complexes I and III, with consequent increased theoretical distance between complexes, determines adherence to pool behavior for Coenzyme Q, but only at dilution higher than 1:5 (protein:phospholipids), whereas, at lower phospholipid content, the turnover of NADH cytochrome c reductase is higher than expected by the pool equation. [source] Bayesian Analysis of Serial Dilution AssaysBIOMETRICS, Issue 2 2004Andrew Gelman Summary. In a serial dilution assay, the concentration of a compound is estimated by combining measurements of several different dilutions of an unknown sample. The relation between concentration and measurement is nonlinear and heteroscedastic, and so it is not appropriate to weight these measurements equally. In the standard existing approach for analysis of these data, a large proportion of the measurements are discarded as being above or below detection limits. We present a Bayesian method for jointly estimating the calibration curve and the unknown concentrations using all the data. Compared to the existing method, our estimates have much lower standard errors and give estimates even when all the measurements are outside the "detection limits." We evaluate our method empirically using laboratory data on cockroach allergens measured in house dust samples. Our estimates are much more accurate than those obtained using the usual approach. In addition, we develop a method for determining the "effective weight" attached to each measurement, based on a local linearization of the estimated model. The effective weight can give insight into the information conveyed by each data point and suggests potential improvements in design of serial dilution experiments. [source] Pain Sensation during Intradermal Injections of Three Different Botulinum Toxin Preparations in Different Doses and DilutionsDERMATOLOGIC SURGERY, Issue 7 2006GOTTFRIED KRANZ MD BACKGROUND Pain sensation associated with injections of botulinum neurotoxin (BoNT) is commonly reported. To date differences in pain sensation between the commercially available products containing BoNT have not been quantified. OBJECTIVES The pain sensations during injection of Dysport, Botox, Neurobloc, and pure saline (control) were compared. In addition, the nociceptive effect of different volumes used for the dilution of the same BoNT dose was investigated. METHODS In a prospective, double-blind, controlled trial, 10 healthy subjects were injected intradermally with Dysport (12 U), Botox (3 and 4 U), Neurobloc (150 and 300 U) reconstituted in 0.9% saline, and pure saline. Pain sensation was quantified during injections. RESULTS Neurobloc injections caused significantly more injection pain than Botox, Dysport, and saline. No significant differences between Dysport, Botox, and saline were found, although there was a trend toward less pain with pure saline injections. Higher pain levels with higher volumes could not be demonstrated significantly. CONCLUSION Our data demonstrate that BoNT type B injections are associated with substantial pain. There is a considerable difference between the commercially available BoNT type B compared to the two BoNT type A preparations. Therefore, considering mitigation of injection pain seems necessary when using BoNT type B. [source] Kinetic Measurements of Protein Conformation in a MicrochipBIOTECHNOLOGY PROGRESS, Issue 5 2006Matthew B. Kerby This paper presents a microchip-based system for collecting kinetic time-based information on protein refolding and unfolding. Dynamic protein conformational change pathways were studied in microchannel flow using a microfluidic device. We present a protein-conserving approach for quantifying refolding by dynamically varying the concentration of the chemical denaturants, guanidine hydrochloride and urea. Short diffusion distances in the microchannel result in rapid equilibrium between protein and titrating solutions. Dilutions on the chip were tightly regulated using pressure controls rather than syringe-based flow, as verified with extensive on-chip tracer dye controls. To validate this protein assay method, folding transition experiments were performed using two well-characterized proteins, human serum albumin (HSA) and bovine carbonic anhydrase (BCA). Transition events were monitored through fluorescence intensity shifts of the protein dye 8-anilino-1-naphthalenesulfonic acid (ANS) during dilutions of protein from urea or guanidine hydrochloride solutions. The enzymatic activity of refolded BCA was measured by UV absorption through the conversion of p -nitrophenyl acetate (p-NPA). The microchip protein refolding transitions using ANS were well-correlated with conventional plate-based experiments. The microfluidic platform enables refolding studies to identify rapidly the optimal folding strategy for a protein using small quantities of material. [source] Evidence of in vivo basophil activation in chronic idiopathic urticariaCLINICAL & EXPERIMENTAL ALLERGY, Issue 6 2006K. Vasagar Summary Background Approximately 40% of chronic idiopathic urticaria (CIU) subjects have autoantibodies to either Fc,RI, or IgE. The effect of such autoantibodies on circulating basophil activation status is unknown. Objective The expression of cell surface activation markers on basophils from CIU, non-allergic, and allergic subjects were compared. Further, the relationship between marker expression and serum factors reported in CIU, such as histamine-releasing activity (HRA) and immunoreactivity to Fc,RI, were examined. Methods Peripheral blood was obtained from CIU, allergic, and non-allergic donors and fractionated by density gradients. Enriched basophils (1,12%) were analysed by flow cytometry for expression of activation markers including CD63, CD69, and CD203c. Dilutions of serum (5,50%) were analysed for HRA on basophils from a normal donor. Serum was tested for immunoreactivity by western blotting to a standard cell lysate prepared from an RBL-SX38 cell line transfected with human Fc,RI,. Results CIU subjects (n=9) and allergic subjects (n=8) exhibited enhanced expression of CD63 and CD69, as compared with non-allergic subjects (n=7); however, no difference was seen among groups for CD203c expression. Five CIU and two non-allergic subjects had evidence of significant serum HRA (>20%), whereas two CIU, two allergic, and three non-allergic subjects had evidence of serum immunoreactivity to Fc,RI,. Serum HRA and serum immunoreactivity to Fc,RI, were not associated with enhanced surface marker expression. Conclusion Basophil activation marker expression is increased in CIU subjects and is not associated with serum factors. In addition, serum HRA and Fc,RI, immunoreactivity are not unique to CIU, or related to enhanced circulating basophil marker expression. [source] Influence of the intermediate digestion phases of common formulation lipids on the absorption of a poorly water-soluble drugJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2005Greg A. Kossena Abstract The influence of different model intestinal phases (modelled on those likely to be produced in vivo after the digestion of commonly used formulation lipids) on the absorption profile of cinnarizine has been studied. Combinations of C8, C12, or C18:1 fatty acid and monoglyceride and simulated endogenous intestinal fluid were formulated to provide examples of liquid (L1), lamellar (L,), and cubic (C) liquid crystalline phases. Phases containing cinnarizine were dosed intraduodenally and absorption was assessed in an anesthetized rat model. Bile duct ligation was performed to inhibit the effects of digestion/dilution on the phase structure. Absorption from the L, phases (C8 and C12 lipids) was statistically higher (p,<,0.05) than a cinnarizine suspension: however, a statistically significant difference was not observed from the L1 and C phases. The rigid C18:1 C phase showed evidence of providing for sustained drug absorption. Experiments in bile intact rats with the C8 L, and C18:1 C phase highlighted that the absorption-modifying properties of these phases were influenced by dilution in the endogenous bile milieu, with absorption from L, phase reducing (possibly through precipitation of solubilized drug) and increasing in the case of the C18:1 C phase, possibly through the coexistence of L1 and C upon dilution permitting more efficient transfer of solubilized drug. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:481,492, 2005 [source] Anaphylactic reaction to intralesional corticosteroid injectionCONTACT DERMATITIS, Issue 2 2007M. E. Laing We report the case of anaphylactic reaction to carboxymethylcellulose, a dispersant in corticosteroid preparation and contrast media. Skin prick testing in this patient revealed a positive response to carboxymethylcellulose at a dilution of 1/1000. Anaphylaxis secondary to carboxymethylcellulose has previously been reported. To avoid further problems, this patient was advised to alert medical staff for the presence of allergy to carboxymethylcellulose in the event of the need for further interventional procedures. Care should be taken when giving intradermal steroids to patients with a history of anaphylaxis after contrast media. [source] A new type of susceptibility-artefact-based magnetic resonance angiography: intra-arterial injection of superparamagnetic iron oxide particles (SPIO) A Resovist® in combination with TrueFisp imaging: a feasibility studyCONTRAST MEDIA & MOLECULAR IMAGING, Issue 5 2006Robbert M. Maes Abstract The goal of this study was to evaluate the use of super paramagnetic particles of iron oxide (SPIO) as a dark blood contrast agent, in combination with a bright blood steady-state free precession sequence for magnetic resonance angiography (MRA), in an animal model. The original concentration of the SPIO of 500,mmol Fe/l and dilutions to 250, 125, 60, 30, 10 and 5,mmol Fe/l were intra-arterially injected into the aorta of a pig. Then the dilution of 10,mmol Fe/l was chosen for repeated intra-arterial injections into two pigs. During these intra-arterial SPIO injections MR images were acquired with a 1.5,T scanner. Signal intensity measurements were performed in the aorta. The signal-to-noise ratio during SPIO bolus passage was significantly less than during baseline conditions (Fisher's F -ratio 159.8, p,<,0.005) or the recovery signal-to-noise ratio (Fisher's F -ratio 144.6, p,<,0.005). Also, confirmation of flow distal to the catheter-tip position was possible. The use of SPIO as a dark blood agent in combination with a bright blood MR imaging sequence is feasible. Temporary loss of intraluminal signal occurs due to local decrease of the signal because of induction of local inhomogeneities after mixture the present blood and SPIO solution. It provides immediate information about blood flow distal to the catheter and is a potentially useful to guide intravascular MR-interventional procedures. Copyright © 2006 John Wiley & Sons Ltd. [source] Flow cytometry antibody screening using pooled red cells,CYTOMETRY, Issue 2 2010Dong Il Won Abstract Background: For red cell alloantibody screening, the column agglutination technique (CAT) is used extensively, and flow cytometry (FC) screening has recently been demonstrated to be accurate, rapid, and cost effective. We attempted to determine whether the high sensitivity of FC allows pooling of screening red cells, which is generally not an acceptable technique in CAT. Methods: For FC screening, a commercial two-cell screening panel was utilized for the preparation of individual cells (CSi), as well as pooled cells diluted 1 in 2 (CSp), and 1 in 3 (CS1/3). Another panel was pooled from 120 randomly selected group O donors (RSp). Results: Comparing the endpoint titrations of serial dilutions, CS1/3 was found to be one dilution, on the average, less sensitive than CSi. In 33 CAT-positive patient samples, the sensitivities of CSi and CSp did not differ significantly without polyethylene glycol (PEG) (30/33, 26/33, respectively, P = 0.125), although they did differ significantly with PEG (32/33, 25/33, respectively, P = 0.016). The percentages of reactive cells among the total cells from RSp were roughly proportional to the relevant antigen frequencies of the local donors. Conclusions: A trend toward reduced sensitivity was observed using pooled red cells, even via FC. Pooled cells from randomly selected group O donors may be employed as another method by which the characteristics of known antibodies might be assessed. © 2009 Clinical Cytometry Society [source] Total nucleated cell differential for blood and bone marrow using a single tube in a five-color flow cytometer,,CYTOMETRY, Issue 2 2008Sven Björnsson Abstract Background: Flow cytometry allows the use of several antibodies in addition to light scatter, and most flow cytometers will provide at least seven measurements on each cell passing through the laser beam. A skilled microscopist will classify at least 14 cell classes in bone marrow or blood. Our goal was to use the seven parameters available in our flow cytometer to provide a reliable differential count using only one tube. Methods: Peripheral blood samples were analyzed on the Beckman Coulter LH750 cell counter, and the flagging and messages from the cell counter were used to select normal or pathological samples. Samples without flags (N = 50), with >2% erythroblasts (N = 80), or with "Blast" or "Verify diff" flags (N = 54) were investigated. We used a lyse-no-wash method to ensure minimal loss of fragile cells with live gating on DRAQ5-positive cells to acquire only nucleated cells. The FL-1 to FL-4 channels were used for the antibodies CD36-FITC, CD203-PE, CD138-PE, CD45-ECD, CD16-Pcy5, and CD56-Pcy5. FL-5 was used for the DNA-stain DRAQ5. Results: Using live gate acquisition on DRAQ5, we were able to classify total nucleated cells into 10 classes. We were unable to identify megakaryocytes, but platelets could be studied by rerunning the sample after dilution and gating on DRAQ5-negative CD36-posive events. Validation against digitized microscopy and cell counter showed linear correlations within each cell class with correlation coefficients that seem reasonable for cellular classification. The lowest correlation was found for basophil granulocytes. Flow cytometry detected twice as many immature neutrophils compared to microscopy. Conclusions: We have designed a one-tube immunophenotyping panel for classification of total nucleated cells and platelets in blood or bone marrow. The seven parameters available in one single tube in our cytometer seem to be enough for reliable differential count even in difficult pathological samples. The analytical imprecision of the flow cytometer differential was much lower than that obtained with microscopy or cell counter differentials. © 2007 Clinical Cytometry Society. [source] Statistical 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] Albumin enhanced morphometric image analysis in CLL,CYTOMETRY, Issue 1 2004Matthew A. Lunning Abstract BACKGROUND The heterogeneity of lymphocytes from patients with chronic lymphocytic leukemia (CLL) and blood film artifacts make morphologic subclassification of this disease difficult. METHODS We reviewed paired blood films prepared from ethylene-diamine-tetraacetic acid (ETDA) samples with and without bovine serum albumin (BSA) from 82 CLL patients. Group 1 adhered to NCCLS specifications for the preparations of EDTA blood films. Group 2 consisted of blood films containing EDTA and a 1:12 dilution of 22% BSA. Eight patients were selected for digital photomicroscopy and statistical analysis. Approximately 100 lymphocytes from each slide were digitally captured. RESULTS The mean cell area ± standard error was 127.8 ,m2 ± 1.42 for (n = 793) for group 1 versus 100.7 ,m2 ± 1.39 (n = 831) for group 2. The nuclear area was 88.9 ,m2 ± 0.85 for group 1 versus 76.4 ,m2 ± 0.83 for group 2. For the nuclear transmittance, the values were 97.6 ± 0.85 for group 1 and 104.1 ± 0.83 for group 2. The nuclear:cytoplasmic ratios were 0.71 ± 0.003 for group 1 and 0.78 ± 0.003 for group 2. All differences were statistically significant (P < 0.001). CONCLUSIONS BSA addition results in the reduction of atypical lymphocytes and a decrease in smudge cells. BSA also decreases the lymphocyte area and nuclear area, whereas nuclear transmittance and nuclear:cytoplasmic ratio are increased. A standardized method of slide preparation would allow accurate interlaboratory comparison. The use of BSA may permit better implementation of the blood film-based subclassification of CLL and lead to a better correlation of morphology with cytogenetics and immunophenotyping. Published 2003 Wiley-Liss, Inc. [source] Mechanisms of intercellular hypertonicity and isotonic fluid absorption in proximal tubules of mammalian kidneysACTA PHYSIOLOGICA, Issue 1 2002F. KIILArticle first published online: 30 APR 200 ABSTRACT The main purpose of this theoretical analysis (second of two articles) is to examine whether transjunctional diffusion of NaCl causes intercellular hypertonicity, which permits transcellular water transport across solute-impermeable lateral cell membranes until osmotic equilibration. In the S2 segment with tubular NaCl concentration 140 mM, the calculated apical intercellular NaCl concentration is c0 , 132 mM, which exceeds peritubular NaCl concentration by 12 mM or 22 mOsm kg,1. Variations in volume flow, junctional reflection coefficient (,NaCl=0.25,0.50), gap distance (g=6,8 Å), junctional depth (d=18,100 Å), intercellular diffusion coefficient (DLIS=500,1500 ,m2 s,1) and hypothetical active NaCl transport alter c0 only by a fraction of 1 mM. However, dilution and back-leakage of NaHCO3 lower apical intercellular hyperosmolality to ,18 mOsm kg,1. Water transport through solute-impermeable lateral cell membranes continues until intercellular and cellular osmolalities are equal. Transcellular and transjunctional volume flow are of similar magnitude (2 nL min,1 mm,1 tubule length) in the S2 segment. Thus, diffusion ensures isotonic absorption of NaCl. Two-thirds of NaHCO3 and other actively transported sodium salts are extruded into the last third of the exponentially widening intercellular space where the exposure time is only 0.9 s. Osmotic equilibration is dependent on aquaporins in the cell membranes. If permeability to water is low, transcellular water transport stops; tubular fluid becomes hypotonic; NaCl diffusion diminishes, but transjunctional water transport remains unaltered as long as transcellular transport of NaHCO3 and other solutes provides the osmotic force. [source] No effect of venoconstrictive thigh cuffs on orthostatic hypotension induced by head-down bed restACTA PHYSIOLOGICA, Issue 2 2000M.-A. Custaud Orthostatic intolerance (OI) is the most serious symptom of cardiovascular deconditioning induced by head-down bed rest or weightlessness. Wearing venoconstrictive thigh cuffs is an empirical countermeasure used by Russian cosmonauts to limit the shift of fluid from the lower part of the body to the cardio-cephalic region. Our aim was to determine whether or not thigh cuffs help to prevent orthostatic hypotension induced by head-down bed rest. We studied the effect of thigh cuffs on eight healthy men. The cuffs were worn during the day for 7 days of head-down bed rest. We measured: orthostatic tolerance (stand tests and lower body negative pressure tests), plasma volume (Evans blue dilution), autonomic influences (plasma noradrenaline) and baroreflex sensitivity (spontaneous baroreflex slope). Thigh cuffs limited the loss of plasma volume (thigh cuffs: ,201 ± 37 mL vs. control: ,345 ± 42 mL, P < 0.05), the degree of tachycardia and reduction in the spontaneous baroreflex sensitivity induced by head-down bed rest. However, the impact of thigh cuffs was not sufficient to prevent OI (thigh cuffs: 7.0 min of standing time vs. control: 7.1 min). Decrease in absolute plasma volume and in baroreflex sensitivity are known to be important factors in the aetiology of OI induced by head-down bed rest. However, dealing with these factors, using thigh cuffs for example, is not sufficient to prevent OI. Other factors such as venous compliance, microcirculatory changes, peripheral arterial vasoconstriction and vestibular afferents must also be considered. [source] Hydrogen Peroxide and Wound Healing: A Theoretical and Practical Review for Hair Transplant SurgeonsDERMATOLOGIC SURGERY, Issue 6 2008SARA WASSERBAUER MD BACKGROUND In most hair restoration practices, hydrogen peroxide has been routinely used to remove blood during and after hair transplant surgery. In other specialties, hydrogen peroxide is also used in these ways: wound cleaning, prevention of infection, hemostasis, and removal of debris. Despite its widespread use, there are still concerns and controversy about the potential toxic effect of hydrogen peroxide. OBJECTIVE The objective was to review all available literature including in vivo and in vitro effects of hydrogen peroxide, as well as general wound healing research. MATERIAL AND METHODS Literature up to and including the past three decades was investigated. RESULTS Two pilot studies were found, and there are not enough data examining the real impact of using hydrogen peroxide in hair transplant surgery. In other specialties, H2O2 appears to have positive effects, such as stimulation of vascular endothelial growth factor, induction of fibroblast proliferation, and collagen, or negative effects, such as cytotoxicity, inhibition of keratinocyte migration, disruption of scarless fetal wound repair, and apoptosis. CONCLUSIONS There are not enough data in hair restoration surgery about the use of hydrogen peroxide, and it is unknown and unclear what the optimum dilution should be. Positive and negative effects were found in other specialties. Further studies are recommended. [source] Pain Sensation during Intradermal Injections of Three Different Botulinum Toxin Preparations in Different Doses and DilutionsDERMATOLOGIC SURGERY, Issue 7 2006GOTTFRIED KRANZ MD BACKGROUND Pain sensation associated with injections of botulinum neurotoxin (BoNT) is commonly reported. To date differences in pain sensation between the commercially available products containing BoNT have not been quantified. OBJECTIVES The pain sensations during injection of Dysport, Botox, Neurobloc, and pure saline (control) were compared. In addition, the nociceptive effect of different volumes used for the dilution of the same BoNT dose was investigated. METHODS In a prospective, double-blind, controlled trial, 10 healthy subjects were injected intradermally with Dysport (12 U), Botox (3 and 4 U), Neurobloc (150 and 300 U) reconstituted in 0.9% saline, and pure saline. Pain sensation was quantified during injections. RESULTS Neurobloc injections caused significantly more injection pain than Botox, Dysport, and saline. No significant differences between Dysport, Botox, and saline were found, although there was a trend toward less pain with pure saline injections. Higher pain levels with higher volumes could not be demonstrated significantly. CONCLUSION Our data demonstrate that BoNT type B injections are associated with substantial pain. There is a considerable difference between the commercially available BoNT type B compared to the two BoNT type A preparations. Therefore, considering mitigation of injection pain seems necessary when using BoNT type B. [source] Low-fat oxidation may be a factor in obesity among men with schizophreniaACTA PSYCHIATRICA SCANDINAVICA, Issue 6 2009J.-K. Sharpe Objective:, Obesity associated with atypical antipsychotic medications is an important clinical issue for people with schizophrenia. The purpose of this project was to determine whether there were any differences in resting energy expenditure (REE) and respiratory quotient (RQ) between men with schizophrenia and controls. Method:, Thirty-one men with schizophrenia were individually matched for age and relative body weight with healthy, sedentary controls. Deuterium dilution was used to determine total body water and subsequently fat-free mass (FFM). Indirect calorimetry using a Deltatrac metabolic cart was used to determine REE and RQ. Results:, When corrected for FFM, there was no significant difference in REE between the groups. However, fasting RQ was significantly higher in the men with schizophrenia than the controls. Conclusion:, Men with schizophrenia oxidised proportionally less fat and more carbohydrate under resting conditions than healthy controls. These differences in substrate utilisation at rest may be an important consideration in obesity in this clinical group. [source] The molecular receptive range of an olfactory receptor in vivo (Drosophila melanogaster Or22a)DEVELOPMENTAL NEUROBIOLOGY, Issue 14 2006Daniela Pelz Abstract Understanding how odors are coded within an olfactory system requires knowledge about its input. This is constituted by the molecular receptive ranges (MRR) of olfactory sensory neurons that converge in the glomeruli of the olfactory bulb (vertebrates) or the antennal lobe (AL, insects). Aiming at a comprehensive characterization of MRRs in Drosophila melanogaster we measured odor-evoked calcium responses in olfactory sensory neurons that express the olfactory receptor Or22a. We used an automated stimulus application system to screen [Ca2+] responses to 104 odors both in the antenna (sensory transduction) and in the AL (neuronal transmission). At 10,2 (vol/vol) dilution, 39 odors elicited at least a half-maximal response. For these odorants we established dose-response relationships over their entire dynamic range. We tested 15 additional chemicals that are structurally related to the most efficient odors. Ethyl hexanoate and methyl hexanoate were the best stimuli, eliciting consistent responses at dilutions as low as 10,9. Two substances led to calcium decrease, suggesting that Or22a might be constitutively active, and that these substances might act as inverse agonists, reminiscent of G-protein coupled receptors. There was no difference between the antennal and the AL MRR. Furthermore we show that Or22a has a broad yet selective MRR, and must be functionally described both as a specialist and a generalist. Both these descriptions are ecologically relevant. Given that adult Drosophila use approximately 43 ORs, a complete description of all MRRs appears now in reach. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source] Matching Response to Context in Complex Political Emergencies: ,Relief', ,Development', ,Peace-building' or Something In-between?DISASTERS, Issue 4 2000Philip White There is an ongoing debate over the value and pitfalls of the policy and practice of ,linking relief and development' or ,developmental relief' in aid responses to complex political emergencies (CPEs). Driven by concerns about relief creating dependence, sometimes doing harm and failing to address root causes of emergencies despite its high cost, pursuit of both relief and development has become a dominant paradigm among international aid agencies in CPEs as in ,natural' disasters. In CPEs a third objective of ,peace-building' has emerged, along with the logic that development can itself help prevent or resolve conflict and sustain peace. However, this broadening of relief objectives in ongoing CPEs has recently been criticised on a number of counts, central concerns being that it leads to a dilution of commitment to core humanitarian principles and is overly optimistic. This paper addresses these issues in the light of two of the CPEs studied by the COPE project: Eritrea and Somalia/Somaliland. It is argued that the debate has so far suffered from lack of clarity about what we mean by ,relief', ,development' and, for that matter, ,rehabilitation' and ,peace-building'. The wide spectrum of possible aid outcomes does not divide neatly into these categories. The relief,development divide is not always as clear-cut, technically or politically, as the critics claim. Moreover such distinctions, constructed from the point of view of aid programmers, are often of little relevance to the concerns of intended beneficiaries. Second, there has been insufficient attention to context: rather than attempting to generalise within and across CPE cases, a more productive approach would be to examine more closely the conditions under which forms of aid other than basic life support can fruitfully be pursued. This leads to consideration of collective agency capacity to respond effectively to diverse needs in different and changing circumstances. [source] Suspended sediment transport in a small Mediterranean agricultural catchmentEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2009Joan Estrany Abstract The aim of this study is to analyze suspended sediment transport in a Mediterranean agricultural catchment under traditional soil and water conservation practices. Field measurements were conducted in Can Revull, a small ephemeral catchment (1.03 km2) on the island of Mallorca. This study uses continuous turbidity records to analyse suspended sediment transport regimes, construct and interpret multiple regression models of total suspended sediment concentration (SSC) and of SSC related to stormflow discharge, and assess the sediment loads and yields of three hydrological years (2004,2005 to 2006,2007). An annual average SSC of 17.3 mg l,1, with a maximum of 2270 mg l,1, was recorded in the middle of the winter period when rainfall intensities are high and headwater slopes are ploughed and thus bare. Strong seasonal contrasts of baseflow dynamics associated with different degrees of dilution provide a large scatter in SSC and in the derived rating curves, reflecting that other factors control the supply of suspended sediment. Multiple regression models identify rainfall intensity as the most significant variable in sediment supply. However, under baseflow conditions, physical and biological processes generate sediment in the channel that is subsequently removed during high flow. In contrast, when baseflow is not present, rainfall intensity is the only process that supplies sediment to the channel, mostly from hillslopes. Considering the study period as average in terms of total annual rainfall and intensities, suspended sediment yields were an order of magnitude lower than those obtained in other Mediterranean catchments, a factor that can be related to the historical use of soil conservation practices. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||