Effect of Different Binders on Release Characteristics of Theophylline from Compressed Microspheres

Microspheres with 60% w/w drug loading were prepared by the solvent-evaporation method using cellulose acetate butyrate as the encapsulating polymer and micronized anhydrous theophylline as the core material. Four different binders - microcrystalline cellulose, glyceryl palmito-stearate, glyceryl stearate and glyceryl behenate were used to compress three different particle sizes of microspheres. Comparison of the in vitro drug dissolution profiles revealed that drug release was fastest from all the microspheres compressed with microcrystalline cellulose as the binder followed by those compressed with glyceryl palmitostearate, glyceryl stearate and glyceryl behenate.     

Cardiac muscarinic receptor function in rats with cirrhotic cardiomyopathy

The pathogenesis of cirrhotic cardiomyopathy remains unclear. Because ventricular contractility is dependent on the interplay of stimulatory beta-adrenergic and inhibitory muscarinic receptors, we aimed to examine a possible role of muscarinic M2 receptor overactivity in a rat model of cirrhotic cardiomyopathy. Cirrhosis was induced by bile duct ligation (BDL), while controls underwent sham operations. Contractile responses to the muscarinic agonist carbachol were measured in situ in the autonomic-denervated pithed rat and in vitro in isolated ventricular papillary muscles. Ventricular sarcolemmal plasma membranes were isolated by sucrose density gradients, and muscarinic receptor characteristics were studied using 1-[N-methyl-3H]scopolamine (NMS). Membrane adenylyl cyclase activity was tested by a protein binding assay. Maximum first time derivative of peak ventricular systolic pressure (+dP/dt) for sham-operated and cirrhotic rats at baseline was 3,599 +/- 296 versus 1,226 +/- 63 mm Hg/sec (P < .01). Maximum first time derivative of ventricular diastolic relaxation (-dP/dt) for sham and cirrhotic rats at basal levels was -3,040 +/- 235 versus -864 +/- 59 (P < .01). The +dP/dt(max), and -dP/dt(max) responses to carbachol were blunted in the cirrhotic rats. The cirrhotic papillary muscles showed significantly less inhibition to incremental doses of carbachol than control rat muscles. Likewise, isoproterenol-stimulated membrane adenylyl cyclase activity was significantly less inhibited by carbachol doses in the cirrhotic rats. Membrane M2 receptor density and binding affinity in cirrhotic rat hearts were similar to controls. We conclude that muscarinic responsiveness was blunted in cirrhotic hearts, but this was not caused by receptor down-regulation, suggesting changes in postreceptor factors. These changes in muscarinic function are likely compensatory, and M2 receptor overactivity is not involved in the genesis of cirrhotic cardiomyopathy.     

Characterization of a Helicobacter pylori neutrophil-activating protein

Antibody-blocking studies have demonstrated the role of CD6 in thymocyte-thymic epithelial (TE) cell adhesion. Here we report that CD6 expressed by COS cells mediates adhesion to TE cells and that this interaction is specifically blocked with an anti-CD6 monoclonal antibody (mAb) or with a mAb (J4-81) that recognized a TE cell antigen. We isolated and expressed a cDNA clone encoding this antigen and show that COS cells transfected with this cDNA bind a CD6 immunoglobulin fusion protein (CD6-Rg). This antigen, which we named ALCAM (activated leukocyte-cell adhesion molecule) because of its expression on activated leukocytes, appears to be the human homologue of the chicken neural adhesion molecule BEN/SC-1/DM-GRASP. The gene was mapped to human chromosome 3q13.1-q13.2 by fluorescence in situ hybridization of cDNA probes to metaphase chromosomes. We prepared an ALCAM-Rg fusion protein and showed that it binds to COS cell transfectants expressing CD6, demonstrating that ALCAM is a CD6 ligand. The observations that ALCAM is also expressed by activated leukocytes and that both ALCAM and CD6 are expressed in the brain suggest that ALCAM-CD6 interactions may play a role in the binding of T and B cells to activated leukocytes, as well as in interactions between cells of the nervous system.     

Dosimetric support of the International Programme on the Health Effects of the Chernobyl Accident (IPHECA) pilot project: main results and problems

The problem of post-Chernobyl dosimetry is unique in its complexity in the history of radiation medicine and radiation protection. This is because the early experience of mass exposure of people (bombing of Hiroshima and Nagasaki, Windscale and South-Ural accidents, exposure of inhabitants of Nevada in the United States of America, the Semipalatinsk area in the former USSR, the Marshall Islands, and the Goi?nia accident in Brazil, and others) differed both in the much simpler structure of the irradiation source and in the number and characteristics of exposed persons. It is obvious that post-Chernobyl dosimetry, both as an independent problem, and as a tool for epidemiological studies, requires significant expertise and economic and technical expenditures. Extensive and deep research has been carried out in Ukraine for the past 10 years. This article reviews the main results of these studies.     

The Response of Hardwood Flakes and Flakeboard to High Temperature Drying

This study assesses the effect of high temperature drying on chemical and mechanical properties of flakes and correlates changes in flake quality with board properties. The high temperature drying of flakes was found to have a significant effect on the internal bond (IB) of the resulting panels. The highest IB values were observed in boards produced from flakes dried at 150°C. Boards produced from flakes dried at 20°C and 350°C exhibited consistently lower values for IB. Opposite trends were noted for total acid content of flake. Multiple regression and correlation analysis revealed a strong relationship between IB, total acid content, and dryer temperature. A significant species effect was also present. Increased levels of flake total acids. acid buffering capacity, and the ratio of acid to base buffering capacities resulted in decreased board property values. Flake bending tests indicated that, in general, the strength and stiffness of the flakes were adversely affected by high temperature drying. This effect did not manifest itself, however, in the resulting panels. Possible reasons for this phenomenon are discussed.     

Escape conditioning in wild and domestic Norway rats.

Tested 16 female wild (lab-reared) and 16 female domestic Norway rats for acquisition of a conditioned escape response. To escape from an aversive stimulus (air blasts) Ss were required to open 1 of 8 doors (simulated burrow entrances) on the presence of a visual cue. Stocks did not differ in the rate of conditioning. Wild Ss exhibited significantly shorter latencies for ambulation and escape than domestic Ss. Removal and reinstatement of the visual cue following acquisition confirmed that the Ss used the cue for orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transient Response of Multiconductor Transmission Lines Excited by a Nonuniform Electromagnetic Field

The time-domain transmission-line equations for uniform multiconductor transmission lines in a conductive, homogeneous medium excited by a transient, nonuniform electromagnetic (EM) field, are derived from Maxwell's equations. Depending on how the line voltage is defined, two formulations are possible. One of these formulations is considerably more convenient to apply than the other. The assumptions made in the derivation of the transmission-line equations and the boundary conditions at the terminations are discussed. For numerical calculations, the transmission -line equations are represented by finite-difference techniques, and numerical examples are included.