Enhancement Ratio (enhancement + ratio)

Distribution by Scientific Domains


Selected Abstracts


Discriminant analysis as a tool to identify compounds with potential as transdermal enhancers

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 11 2005
W. J. Pugh
Structure-activity relationships were sought for 73 enhancers of hydrocortisone permeation from propylene glycol across hairless mouse skin. Enhancers had chain lengths (CC) from 0 to 16 carbon atoms, 1 to 8 H-bonding atoms (HB), molecular weight 60 to 450, log P (calculated) ,1.7 to 9.7 and log S (calculated) ,7.8 to 0.7. These predictive properties were chosen because of their ready availability. Enhancement ratio (ER) was defined as hydrocortisone transferred after 24 h relative to control. Values for the ER ranged from 0.2 to 25.3. Multiple regression analysis failed to predict activity; ER values for the ,good' enhancers (ER>10) were underestimated. Simple guidelines suggested that high ER was associated with CC>12 and HB 2,5. This was refined by multivariate analysis to identify significant predictors. Discriminant analysis using CC, HB, and molecular weight correctly assigned 11 of the 12 ,good' enhancers (92%). The incorrectly assigned compound was a known, idiosyncratic Br compound. Seventeen of the 61 ,poor' enhancers (28%) were incorrectly assigned but four could be considered marginal (ER>8). The success of this simple approach in identifying potent enhancers suggested its potential in predicting novel enhancer activity. [source]


Dynamic MRI, dynamic multidetector-row computed tomography (MDCT), and coregistered 2-[fluorine-18]-fluoro-2-deoxy-D-glucose,positron emission tomography (FDG-PET)/CT: Comparative study of capability for management of pulmonary nodules

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2008
Yoshiharu Ohno MD
Abstract Purpose To compare the nodule management capabilities of dynamic MRI, dynamic multidetector-row computed tomography (MDCT) and coregistered positron emission tomography (PET)/CT. Materials and Methods Dynamic MRI, dynamic MDCT, PET, microbacterial, and pathological examinations were administered to 175 consecutive patients with 202 nodules (<30 mm in diameter). The final diagnoses resulted in the classification of 202 nodules into two groups: requiring further intervention and treatment (N = 163) and no further evaluation (N = 39) groups. Maximum relative enhancement and slope of enhancement ratio were calculated as dynamic MR indices. Maximum enhancement, net enhancement, slope of enhancement, and absolute loss of enhancement were calculated as dynamic CT indices. maximum value of standard uptake value (SUVmax) was measured on coregistered PET/CT. Receiver operating characteristics (ROC) analyses were performed to determine feasible threshold values for nodule management, and results were tested using McNemar's test. Results When feasibility threshold values were adopted for nodule management, the specificity (82.1%) and accuracy (93.6%) of the slope of the enhancement ratio were significantly higher than those of dynamic CT indices (P < 0.05) and SUVmax (P < 0.05). Conclusion Dynamic MRI can play a more specific and/or accurate role for nodule management as compared with dynamic MDCT and coregistered PET/CT. J. Magn. Reson. Imaging 2008;27:1284,1295. © 2008 Wiley-Liss, Inc. [source]


Elastic liposomes mediated transdermal delivery of an anti-hypertensive agent: Propranolol hydrochloride

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2007
Dinesh Mishra
Abstract One major problem encountered in transdermal drug delivery is the low permeability of drugs through the skin barrier. In the present investigation ultradeformable lipid vesicles, that is, elastic liposomes were prepared incorporating propranolol hydrochloride for enhanced transdermal delivery. Elastic liposomes bearing propranolol hydrochloride were prepared by conventional rotary evaporation method and characterized for various parameters including vesicles shape and surface morphology, size and size distribution, entrapment efficiency, elasticity, turbidity, and in vitro drug release. In vitro flux, enhancement ratio (ER), and release pattern of propranolol hydrochloride were calculated for transdermal delivery. In vivo study conducted on male albino rats (Sprague Dawley) was also taken as a measure of performance of elastic liposomal, liposomal, and plain drug solution. The better permeation through the skin was confirmed by confocal laser scanning microscopy (CLSM). Results indicate that the elastic liposomal formulation for transdermal delivery of propranolol hydrochloride provides better transdermal flux, higher entrapment efficiency, ability as a self-penetration enhancer and effectiveness for transdermal delivery as compared to liposomes. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96:145,155, 2007 [source]


In vitro percutaneous penetration of acyclovir from solvent systems and Carbopol 971-P hydrogels: Influence of propylene glycol

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2005
O. Díez-Sales
Abstract The mechanism underlying propylene glycol (PG) effects on acyclovir (ACV) penetration through human epidermis were studied. Solvent systems and Carbopol gels containing increasing percentage of PG (from 0% to 70%, w/w) were used. Viscosity studies of both vehicles were carried out to characterise the influence of rheological behaviour. In solvent systems skin permeation values of ACV increase as the concentration of PG increase yielding a maximum enhancement ratio (ER,=,10) for 70% PG. The release rate of ACV from gels was determined. Higuchi's model was used to estimate the apparent diffusion coefficient of the drug. These values show a decrease as the content of PG in the vehicle increases; this effect could be attributed to the increase of the viscosity in the diffusional pathway. When gels are used skin permeation values of ACV were smaller than those of the solvent systems. This could be attributed to the network structure created by the polymer that increases the length of the diffusional pathway. The maximum ER (=6.8) was for Carbopol gel containing 50% PG. Therefore, these gels can be considered candidates for further research to confirm their usefulness as delivery systems for ACV topical formulations. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1039,1047, 2005 [source]


Dynamic oxygen-enhanced MRI reflects diffusing capacity of the lung

MAGNETIC RESONANCE IN MEDICINE, Issue 6 2002
Yoshiharu Ohno
Abstract The purpose of this study was to demonstrate the feasibility of dynamic oxygen-enhanced MRI in a clinical setting. We hypothesized that dynamic oxygen enhancement can reflect the regional diffusing capacity of the lung. Ten patients with pulmonary emphysema and seven healthy volunteers were examined with a respiratory-synchronized inversion recovery single-shot turbo spin-echo sequence (TR = 3200,5000 ms, TE = 16 ms, TI = 720 ms, ETS = 4 ms) following 100% oxygen inhalation, using a 1.5 T whole-body scanner. Maximum mean relative enhancement ratios calculated by averaging six defined regions of interest (ROIs) in both lungs were statistically compared between healthy volunteers and patients, and were correlated with diffusing lung capacity (%DLCO). In patients with pulmonary emphysema, maximum mean relative enhancement ratios were significantly decreased compared to those in healthy volunteers (P = 0.0008). Maximum mean relative enhancement ratio had excellent correlation with % DLC0 (r2 = 0.83). Dynamic oxygen-enhanced MRI may reflect the diffusing capacity of the lung; therefore, imaging of oxygen enhancement with MRI may provide maps of the diffusing capacity. Magn Reson Med 47:1139,1144, 2002. © 2002 Wiley-Liss, Inc. [source]


MRI and S-MRCP findings in patients with suspected chronic pancreatitis: Correlation with endoscopic pancreatic function testing (ePFT)

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010
N. Cem Balci MD
Abstract Purpose: To review magnetic resonance imaging (MRI) and secretin stimulated magnetic resonance cholangiopancreatography (S-MRCP) findings of patients with suspected chronic pancreatitis and compare them with endoscopic pancreatic function testing (ePFT). Materials and Methods: MRI and S-MRCP findings of 36 patients with clinically suspected chronic pancreatitis were reviewed. Baseline ductal changes, duodenal filling grades, and pancreatic duct caliber change (PDC) on S-MRCP, mean values of pancreatic anteroposterior (AP) diameter, signal intensity ratio (SIR) between pancreas and the spleen on T1-weighted fat saturated images, and arterial to venous (A/V) enhancement ratios were compared between groups of normal and abnormal pancreatic exocrine function determined by ePFT. Results: All patients (n = 24) with normal ePFT (HCO3 >80 mEq/L) had grade 3 normal duodenal filling. Patients with abnormal ePFT (HCO3 <80 mEq/L) (n = 12) had grade 1 (n = 1) and grade 2 (n = 11) diminished duodenal filling (P < 0.0001). PDC was 1.51 in the normal ePFT group versus 1.27 in the abnormal ePFT group (P = 0.01). No significant differences were found in terms of mean pancreatic AP diameter (21.8 vs. 19.8 cm), SIR (1.59 vs. 1.44), and A/V (1.08 vs. 1.01) between groups of normal/abnormal pancreatic exocrine function. Conclusion: Despite discrepancies between pancreatic exocrine function and the findings on standard MRI/MRCP, the S-MRCP findings are comparable to ePFT in the evaluation of chronic pancreatitis. J. Magn. Reson. Imaging 2010;31:601,606. © 2010 Wiley-Liss, Inc. [source]


Dynamic oxygen-enhanced MRI reflects diffusing capacity of the lung

MAGNETIC RESONANCE IN MEDICINE, Issue 6 2002
Yoshiharu Ohno
Abstract The purpose of this study was to demonstrate the feasibility of dynamic oxygen-enhanced MRI in a clinical setting. We hypothesized that dynamic oxygen enhancement can reflect the regional diffusing capacity of the lung. Ten patients with pulmonary emphysema and seven healthy volunteers were examined with a respiratory-synchronized inversion recovery single-shot turbo spin-echo sequence (TR = 3200,5000 ms, TE = 16 ms, TI = 720 ms, ETS = 4 ms) following 100% oxygen inhalation, using a 1.5 T whole-body scanner. Maximum mean relative enhancement ratios calculated by averaging six defined regions of interest (ROIs) in both lungs were statistically compared between healthy volunteers and patients, and were correlated with diffusing lung capacity (%DLCO). In patients with pulmonary emphysema, maximum mean relative enhancement ratios were significantly decreased compared to those in healthy volunteers (P = 0.0008). Maximum mean relative enhancement ratio had excellent correlation with % DLC0 (r2 = 0.83). Dynamic oxygen-enhanced MRI may reflect the diffusing capacity of the lung; therefore, imaging of oxygen enhancement with MRI may provide maps of the diffusing capacity. Magn Reson Med 47:1139,1144, 2002. © 2002 Wiley-Liss, Inc. [source]