scholarly journals Preparation, Characterization, and In Vivo Evaluation of Olanzapine Poly(D,L-lactide-co-glycolide) Microspheres

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Susan D’Souza ◽  
Jabar A. Faraj ◽  
Stefano Giovagnoli ◽  
Patrick P. DeLuca
Keyword(s):  
Molecular Weight ◽  
Steady State ◽  
Copolymer Composition ◽  
Low Molecular Weight ◽  
Multiple Dosing ◽  
In Vivo Evaluation ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Steady State Levels

The aim of this study was to prepare injectable depot formulations of Olanzapine using four poly(D,L-lactide-co-glycolide) (PLGA) polymers of varying molecular weight and copolymer composition, and evaluate in vivo performance in rats. In vivo release profiles from the formulations were governed chiefly by polymer molecular weight and to a lesser extent, copolymer composition. Formulations A and B, manufactured using low molecular weight PLGA and administered at 10 mg/kg dose, released drug within 15 days. Formulation C, prepared from intermediate molecular weight PLGA and administered at 20 mg/kg dose, released drug in 30 days, while Formulation D, manufactured using a high molecular weight polymer and administered at 20 mg/kg dose, released drug in 45 days. A simulation of multiple dosing at 7- and 10-day intervals for Formulations A and B revealed that steady state was achieved within 7–21 days and 10–30 days, respectively. Similarly, simulations at 15-day intervals for Formulations C and D indicated that steady state levels were reached during days 15–45. Overall, steady state levels for 7-, 10-, or 15-day dosing ranged between 45 and 65 ng/mL for all the formulations, implying that Olanzapine PLGA microspheres can be tailored to treat patients with varying clinical needs.

Experimental Study on Flow-Front Fingering Instabilities in Injection Molding of Polymer Solutions and Melts

2004 ◽  
Author(s):  
Kalonji K. Kabanemi ◽  
Jean-Franc¸ois He´tu ◽  
Samira H. Sammoun
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Polymer Solutions ◽  
Low Molecular Weight ◽  
Flow Front ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Polymer Molecules ◽  
Molecular Weights ◽  
Solvent Molecules

An experimental investigation of the flow behavior of dilute, semi-dilute and concentrated polymer solutions has been carried out to gain a better understanding of the underlying mechanisms leading to the occurrence of instabilities at the advancing flow front during the filling of a mold cavity. Experiments were performed using various mass concentrations of low and high molecular weight polyacrylamide polymers in corn syrup and water. This paper reports a new type of elastic fingering instabilities at the advancing flow front that has been observed only in semi-dilute polymer solutions of high molecular weight polymers. These flow front elastic instabilities seem to arise as a result of a mixture of widely separated high molecular weight polymer molecules and low molecular weight solvent molecules, which gives rise to a largely non-uniform polydisperse solution, with respect to all the kinds of molecules in the resulting mixture (solvent molecules and polymer molecules). The occurrence of these instabilities appears to be independent of the injection flow rate and the cavity thickness. Moreover, these instabilities do not manifest themselves in dilute or concentrated regimes, where respectively, polymer molecules and solvent molecules are minor perturbation of the resulting solution. In those regimes, smooth flow fronts are confirmed from our experiments. Based on these findings, the experimental investigations have been extended to polymer melts. Different mixtures of polycarbonate melts of widely separated molecular weights (low and high molecular weights) were first prepared. The effect of the large polydispersity of the resulting mixtures on the flow front behavior was subsequently studied. The same instabilities at the flow front were observed only in the experiments where a very small amount of high molecular weight polycarbonate polymer has been mixed to a low molecular weight polycarbonate melt (oligomers).

scholarly journals The Impact of the Low Molecular Weight Heparin Tinzaparin on the Sensitization of Cisplatin-Resistant Ovarian Cancers—Preclinical In Vivo Evaluation in Xenograft Tumor Models

Molecules ◽  
2017 ◽  
Vol 22 (5) ◽  
pp. 728 ◽  
Author(s):  
Thomas Mueller ◽  
Daniel Pfankuchen ◽  
Kathleen Wantoch von Rekowski ◽  
Martin Schlesinger ◽  
Franziska Reipsch ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Xenograft Tumor ◽  
Tumor Models ◽  
In Vivo Evaluation ◽  
Ovarian Cancers ◽  
The Impact

scholarly journals THE NON-VIRUS PROTEINS ASSOCIATED WITH TOBACCO MOSAIC VIRUS

1955 ◽  
Vol 38 (4) ◽  
pp. 459-473 ◽  
Author(s):  
Barry Commoner ◽  
Mas Yamada
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Infected Plant ◽  
Infected Leaf ◽  
Low Molecular Weight ◽  
Tobacco Plants ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Derivatives Of ◽  
Virus Proteins

1. Exhaustive fractionation of leaves from tobacco plants systemically infected with TMV has led to the isolation of two non-virus proteins, B3 and B6, and the detection of a third, A4, which do not occur in comparable uninfected plants. 2. Components B3 and B6 have been found consistently in a series of ten extracts from plants grown over an 18 month period in all seasons of the year. It is concluded that these components are as characteristic of the infected plant as TMV itself. 3. As they occur in the initial extracts, the non-virus proteins are of low molecular weight (S20 ca. 3). On treatment, each component tends to form a high molecular weight polymer with an electrophoretic mobility considerably greater than that of the starting material. The high molecular weight derivatives of A4, B3, and B6 have been designated A8, B8, and B7 respectively. There is no evidence that these high molecular weight components occur as such in the infected leaf. 4. The non-virus proteins are free of nucleic acid and are not infectious. They cross-react immunochemically with TMV. 5. Compared with TMV content, the amounts of the non-virus proteins found in infected leaf are relatively small, falling in the range of 10 to 150 micrograms per gm. of tissue.

scholarly journals PROCEDURE FOR DETERMINATION OF THE MOLECULAR WEIGHT OF CHITOSAN BY VISCOMETRY

2018 ◽  
Vol XXIII ◽  
pp. 45-54 ◽  
Author(s):  
Renata Czechowska-Biskup ◽  
Radosław A. Wach ◽  
Janusz M. Rosiak ◽  
Piotr Ulański
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Accurate Determination ◽  
Low Molecular Weight ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Experimental Procedure ◽  
Initial Concentration ◽  
Analytical Instruments

The aim of this publication is to facilitate the estimation of chitosan molecular weight (MW) in laboratories with no access to sophisticated analytical instruments, by applying the easily accessible and economical capillary viscometry. The procedure of viscosity-average molecular weight (Mv) determination is described in details. The examples provided encompass testing of the experimental procedure for determination of the Mv of chitosan with a low-molecular weight of 7.7 kDa and 88 kDa, after verification with a high-molecular weight polymer (477 kDa). The experimental work demonstrated the importance of the initial concentration of low-MW chitosan for the accurate determination of intrinsic viscosity and, as a consequence, the viscosity-average molecular weight.

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