Biomedical subjects

F Svec

Publications and source records attributed to F Svec.

167 records · Page 10Linked to original sources

PubMedDate not supplied

Effect of DHEA on macronutrient selection by Zucker rats.

Zucker rats are a frequently used model in obesity research. Dehydroepiandrosterone (DHEA) reduces their rate of weight gain and caloric consumption. So far, most studies have been conducted while the animals consume laboratory rodent chow, which is low in fat. In the experiments of this communication, Zucker rats were offered fat as a food choice. The goal was to determine how the consumption of fat would affect their weight gain and what effect DHEA would have on macronutrient selection. It was found that Zucker rats both male and female, lean and obese selected nearly 40% of their calories as fat when allowed to choose from nearly pure carbohydrate, protein, and fat foodstuffs. Consuming these three macronutrient diets they ate more calories and gained more weight than chow-fed controls over short periods of time. DHEA administered as an intraperitoneal injection decreased caloric intake of Zuckers. This decrement was quantitatively most important on fat intake. DHEA also prevented weight gain. It is concluded that the availability of fat food affects weight gain in Zucker rats and that DHEA modifies the selection of food such that Zucker rats eat less fat.

Animals↗

PubMedDate not supplied

Fast ion-exchange HPLC of proteins using porous poly(glycidyl methacrylate-co-ethylene dimethacrylate) monoliths grafted with poly(2-acrylamido-2-methyl-1-propanesulfonic acid).

Porous poly(glycidyl methacrylate-co-ethylene dimethacrylate) monoliths with different porous properties grafted with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) chains using cerium(IV) initiated free-radical polymerization have been prepared and used for the separation of proteins in ion-exchange HPLC mode. Because of the presence of the large pores that are typical of monolithic separation media which allow easy flow of all of the mobile phase, the efficiency of the columns does not deteriorate even at high flow velocities as a result of the specific morphology of the monoliths. Optimization of the chromatographic conditions such as the shape of the mobile phase gradient and the flow rate allows for very fast separation of three proteins in less than 1.5 min.

Adsorption↗

PubMedDate not supplied

Grafted macroporous polymer monolithic disks: a new format of scavengers for solution-phase combinatorial chemistry.

Polyethylene encased porous poly(chloromethylstyrene-co-divinylbenzene) disks have been prepared by polymerization in a cylindrical glass mold and cut to a disk format. Following attachment of a free radical azo initiator 4,4'-azobis(4-cyanovaleric acid) to available functionalities at the surface of the pores, the polymerization of 2-vinyl-4,4-dimethylazlactone was initiated from the surface. To avoid an undesirable increase in flow resistance and to improve the yield of grafting, divinylbenzene was added to the polymerization mixture in order to form a layer of swellable reactive polymer gel within the pores. The use of these disks as scavenging filters to remove various amines from solutions in flow-through operations was demonstrated by effective removal of amines in a very short period of time from their solutions in a variety of solvents, even including alcohols and water.

Amines↗

PubMedDate not supplied

Hydrophilic polymer supports for solid-phase synthesis: preparation of poly(ethylene glycol) methacrylate polymer beads using "classical" suspension polymerization in aqueous medium and their application in the solid-phase synthesis of hydantoins.

Lightly cross-linked hydrophilic polymer beads representing new types of supports for solid-phase synthesis have been prepared from commercial oligoethylene glycol monomethacrylates using an aqueous suspension polymerization process and specifically designed polymerization mixtures. These beads swell extensively in solvents with a wide range of polarities from dichloromethane, tetrahydrofuran, and water to dimethylformamide, and they enable high functional loadings of 1.2-1.8 mmol g(-1). Their ability to serve as supports was demonstrated in the model solid-phase synthesis of a small library of hydantoins. This four-step synthesis using primary amines readily affords yields of over 70%.

Amines↗

PubMedDate not supplied

Solid-phase acylating reagents in new format: macroporous polymer disks.

Acylation resins in a new monolithic format have been prepared by the functionalization of polyethylene-encased porous poly(chloromethylstyrene-co-divinylbenzene) disks. These disks have been obtained from a monolithic rod prepared by polymerization in a cylindrical glass mold, then cut into a disk format. A free radical azo initiator 4,4'-azobis(4-cyanovaleric acid) attached to available chloromethyl functionalities at the surface of the pores was used to initiate graft polymerization of 4-acetoxystyrene or chloromethylstyrene from the surface. Addition of a small percentage of divinylbenzene to the polymerization mixture leads to the formation of a layer of swellable reactive polymer gel at the surface of the macropores. This both prevents the undesirable increase in flow resistance through the monolith and improves the yield of grafting. The final reaction steps involve formation of an active phenolic moiety grafted to the disks and its reaction with acid anhydride. The use of grafted disks as acylating resin to transform various amines to amides in flow-through operations is demonstrated in a variety of solvents including alcohols. The acylation ability of the depleted disks can easily be recovered, and the disks can be reused many times.

Acetylation↗