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Chamber Volume (chamber + volume)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Mimic of a large-scale diafiltration process by using ultra scale-down rotating disc filter

BIOTECHNOLOGY PROGRESS, Issue 2 2010
Guijun Ma
Abstract Ultra scale-down (USD) approach is a powerful tool to predict large-scale process performance by using very small amounts of material. In this article, we present a method to mimic flux and transmission performance in a labscale crossflow operation by an USD rotating disc filter (RDF). The Pellicon 2 labscale system used for evaluation of the mimic can readily be related to small pilot and industrial scale. Adopted from the pulsed sample injection technique by Ghosh and Cui (J Membr Sci. 2000;175:5-84), the RDF has been modified by building in inserts to allow the flexibility of the chamber volume, so that only 1.5 mL of processing material is required for each diafiltration experiment. The reported method enjoys the simplicity of dead-end mode operation with accurate control of operation conditions that can mimic well the crossflow operation in large scale. Wall shear rate correlations have been established for both the labscale cassette and the USD device, and a mimic has been developed by operating both scales under conditions with equivalent averaged shear rates. The studies using E. coli lysate show that the flux vs. transmembrane pressure profile follows a first-order model, and the transmission of antibody fragment (Fab,) is independent of transmembrane pressure. Predicted flux and transmission data agreed well with the experimental results of a labscale diafiltration where the cassette resistance was considered. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source]

Evaluation of anterior segment parameter changes using the Pentacam after uneventful phacoemulsification

ACTA OPHTHALMOLOGICA, Issue 5 2010
Selim Doganay
Abstract. Purpose:, This study set out to evaluate the influences of uneventful phacoemulsification on the anterior segment parameters obtained with the Pentacam rotating Scheimpflug camera and intraocular pressure (IOP). Methods:, A total of 42 eyes of 34 patients (26 men, eight women) were evaluated preoperatively, and at 1, 3 and 6 months postoperatively with the Pentacam. Intraocular pressure was measured with the Goldmann applanation tonometer. The non-parametric paired t -test was used to compare preoperative and 1-, 3- and 6-month postoperative measurements of anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA) width, central corneal thickness (CCT), the central 3-, 5- and 7-mm corneal volume (CV), pupil size, and IOP. Pearson's correlation test was used to evaluate the relationships between IOP and ACD, ACV and ACA width. Results:, The differences between ACD, ACV, ACA and IOP values taken preoperatively and those taken postoperatively at 1, 3 and 6 months were statistically significant (p < 0.05). The differences between CCT, central 3-, 5- and 7-mm CV, and pupil size measurements taken preoperatively and those taken postoperatively at 1, 3 and 6 months were not statistically significant (p > 0.05). The decrease in IOP was not correlated with the changes in ACD, ACV and ACA (p > 0.05). Conclusions:, Uneventful phacoemulsification significantly reduced IOP, increased ACD and ACV, and widened the ACA. However, alterations in CV, CCT and pupil size values were not statistically significant. Alterations in ACD, ACV, ACA and IOP remain stable after the first month of surgery. [source]

Anterior chamber parameters measured by the Pentacam CES after uneventful phacoemulsification in normotensive eyes

ACTA OPHTHALMOLOGICA, Issue 5 2009
Özlenen Ö. Uçakhan
Abstract. Purpose:, We set out to quantify changes in the anterior chamber volume (ACV), anterior chamber depth (ACD) and anterior chamber angle (ACA) measurements obtained by the Pentacam rotating Scheimpflug camera following uneventful phacoemulsification surgery in normotensive eyes with open iridocorneal angles. Methods:, We enrolled 44 eyes of 44 consecutive patients undergoing cataract extraction in this prospective study. Patients with a history of glaucoma, angle-closure glaucoma or any other concurrent ocular disease were excluded. A detailed eye examination including intraocular pressure (IOP) measurement was performed and ACV, ACD and inferior, superior, temporal and nasal ACA measurements were obtained in each patient eye using the Pentacam Comprehensive Eye Scanner (Pentacam CES) before and 3 months after phacoemulsification and intraocular lens (IOL) implantation with temporal clear corneal incision. Data were compared using paired t -test and one-way anova. Results:, Mean preoperative ACV, ACD, ACA and IOP measurements were 164.7 ± 49.8 mm3, 3.0 ± 0.8 mm, 35.7 ± 10.2 ° and 15.8 ± 3.7 mmHg, respectively. Three months postoperatively, mean ACV, ACD, ACA and IOP measurements were 200.9 ± 33.3 mm3, 3.9 ± 0.9 mm, 41.5 ± 6.5 ° and 13.2 ± 3.9 mmHg, respectively. Postoperative mean ACV, ACD and ACA values in all four quadrants were significantly increased (p < 0.0001, p < 0.0001, p < 0.0001, respectively), whereas IOP was significantly reduced (p < 0.0001). Conclusions:, The Pentacam CES allowed very easy, fast, automatic and non-contact quantification of the anterior chamber parameters pre- and postoperatively in all patient eyes. Measurements obtained confirm that in normotensive eyes with open iridocorneal angles, the ACV and ACD increase and the ACA widens in all quadrants 3 months after uneventful phacoemulsification and IOL implantation. These changes are accompanied by a significant fall in IOP in the short term. [source]

An antidiabetic thiazolidinedione induces eccentric cardiac hypertrophy by cardiac volume overload in rats

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1-2 2004
Kenji Arakawa
Summary 1.,To assess the involvement of volume overload in the development of cardiac hypertrophy during treatment with an antidiabetic thiazolidinedione, changes in cardiac anatomy and parameters of cardiac volume overload were evaluated in female Sprague-Dawley rats treated with the thiazolidinedione derivative T-174. 2.,Two week administration of T-174 (13 and 114 mg/kg per day) increased absolute and relative heart weights by 11,24%, demonstrating the development of cardiac hypertrophy. There was no evidence of oedema in hearts from treated rats. 3.,Both plasma and blood volumes were increased in T-174-treated rats without any changes in systolic blood pressure and heart rate, whereas haematocrit was decreased. In accordance with the existence of volume overload, both left ventricular end-diastolic pressure and right atrial pressure were increased. Morphometric analysis of hearts revealed that T-174 induced eccentric heart hypertrophy, as characterized by a small increase in wall thickness and a large increase in the chamber volume, which is characteristic of volume overload. Volume overload is suggested as the possible trigger mechanism because blood volume expansion preceded cardiac hypertrophy and there was a high correlation between heart weight and blood volume. 4.,T-174-treated streptozotocin-induced diabetic rats also exhibited blood volume expansion and cardiac hypertrophy. 5.,These findings suggest that cardiac volume overload is induced by plasma volume expansion and contributes to the development of eccentric cardiac hypertrophy during treatment with antidiabetic thiazolidinediones. Although thiazolidinediones are insulin-sensitizing agents, these cardiac effects are likely to be mediated independently of insulin. [source]

Association of Coronary Sinus Diameter with Pulmonary Hypertension

ECHOCARDIOGRAPHY, Issue 9 2008
Yilmaz Gunes M.D.
Background: Impaired venous drainage secondary to increased right atrial pressure (RAP) may result in coronary sinus (CS) dilatation.,Methods: Two hundred fifteen patients referred for transthoracic echocardiography were included in the study. CS diameters were measured from apical four-chamber view with the transducer being slightly tilted posteriorly to the level of the dorsum of the heart. Pulmonary artery systolic pressure (PASP) is estimated by measurement of tricuspid regurgitation velocity (v) and estimate RAP based on size and collapsibility of inferior vena cava (VCI) with the formula PASP: 4v2+RAP. Patients with PASP >35 mmHg were considered to have pulmonary hypertension (PH).,Results: CS diameter was measured in 80.3% of the patients with normal PASP (8.1 ± 2.4 mm) and 93.1% of the patients having PH (12.3 ± 2.5 mm). PASP was significantly correlated with CS diameter (r = 0.647, P < 0.001), RA volume index (r = 0.631, P < 0.001), RV volume index (r = 0.475, P < 0.001), VCI diameter (r = 0.365, P < 0.001), and left ventricular ejection fraction (LVEF) (r =,0.270, P < 0.001). CS diameter was also correlated significantly with estimated RAP (r = 0.557, P < 0.001), RA volume index (r = 0.520, P < 0.001), RV volume index (r = 0.386, P < 0.001), LVEF (r =,0.327, P < 0.001), and VCI diameter (r = 0.313, P < 0.001). Multivariate analyses, testing for independent predictive information of CS size, VCI diameter, RA and RV volume indexes, and estimated RAP for the presence of PH revealed that estimated RAP (beta = 0.465, P < 0.001) and CS size (beta = 0.402, P = 0.003) were the significant predictors.,Conclusions: Coronary sinus is dilated in patients with pulmonary hypertension. Coronary sinus diameter significantly correlates with PASP, RAP, right heart chamber volumes, LVEF, and VCI diameter. [source]