Transport of dextran sulfates to rat livers

Gene silencing reveals multiple functions of Na+/K+-ATPase in the salmon louse (Lepeophtheirus salmonis)

Na⁺/K⁺-ATPase has a key function in a variety of physiological processes including membrane excitability, osmoregulation, regulation of cell volume, and transport of nutrients. While knowledge about Na⁺/K⁺-ATPase function in osmoregulation in crustaceans is extensive, the role of this enzyme in other physiological and developmental processes is scarce. Here, we report characterization, transcriptional distribution and likely functions of the newly identified L. salmonis Na⁺/K⁺-ATPase (LsalNa⁺/K⁺-ATPase) α subunit in various developmental stages. The complete mRNA sequence was identified, with 3003 bp open reading frame encoding a putative protein of 1001 amino acids. Putative protein sequence of LsalNa⁺/K⁺-ATPase revealed all typical features of Na⁺/K⁺-ATPase and demonstrated high sequence identity to other invertebrate and vertebrate species. Quantitative RT-PCR analysis revealed higher LsalNa⁺/K⁺-ATPase transcript level in free-living stages in comparison to parasitic stages. In situ hybridization analysis of copepodids and adult lice revealed LsalNa⁺/K⁺-ATPase transcript localization in a wide variety of tissues such as nervous system, intestine, reproductive system, and subcuticular and glandular tissue. RNAi mediated knock-down of LsalNa⁺/K⁺-ATPase caused locomotion impairment, and affected reproduction and feeding. Morphological analysis of dsRNA treated animals revealed muscle degeneration in larval stages, severe changes in the oocyte formation and maturation in females and abnormalities in tegmental glands. Thus, the study represents an important foundation for further functional investigation and identification of physiological pathways in which Na⁺/K⁺-ATPase is directly or indirectly involved.

Effect of the Chemical Modification of Dextran on the Degradation by Rat Liver Lysosomal Enzymes

The biodegradation of dextran, reduced dextran dialdehyde and dextran monosuccinate ester was investigated using isolated rat liver lysosomes. It was demonstrated that chemical modification of the parent dex tran resulted in a reduced degradability. The action of the exo-enzyme α-glucos idase (α-D-glucoside glucohydrolase) was nearly the same for parent dextran as for the derivatives. In order to explain the degradation data, the presence of the endo-acting enzyme dextranase (1,6-α-D-glucan 6-glucanohydrolase) in the lysosomes was taken into account.

Reduction of low-density lipoproteins with dextran sulfate in patients with familial hypercholesterolemia

A novel on-line system for the selective precipitation of low-density lipoprotein (LDL) using dextran sulfate has been devised and tested in four patients with heterozygous familial hypercholesterolemia (type II). The mean pretreatment serum cholesterol was 410 mg/dl. Plasma was generated by membrane filtration and LDL and VLDL (very-low-density lipoprotein) were completely precipitated with 10-35 mg% dextran sulfate (Mr 5,000) in the presence of 55 mM Ca2+. The precipitate was removed by filtration and the excess Ca2+ by dialysis. For 41 procedures the mean reduction of plasma solutes was LDL + VLDL 65%, HDL 23%, fibrinogen 19%, albumin 15%, IgG 20%, IgA 19%, IgM 24%. We conclude that dextran sulfate precipitation is an effective method for selective on-line removal of LDL from plasma.

Induction of metallothionein in liver and changes of essential metal levels in selected tissues by three dextran derivatives

Three dextran derivatives (dextran sulfate, DEAE-dextran and Dextran T500) were injected intraperitoneally into mice to study the induction of zinc-thionein in the liver, and the changes of essential metal levels in the liver, kidneys and spleen. The former was investigated with a high performance liquid chromatograph equipped with an atomic absorption spectrophotometer, and the latter with an inductively coupled plasma-atomic emission spectrometer. Dextran sulfate and DEAE-dextran induced a large amount of hepatic zinc-thionein dose-dependently, while Dextran T500 did not induce metallothionein substantially at the doses studied 20, 40 and 60 mg/kg body wt). The injection of dextran sulfate resulted in a significant increase of spleen weight, with a transitory increase of calcium concentration in the three tissues and a significant decrease of iron level in the spleen. In accord with the induction of zinc-thionein by dextran sulfate and DEAE-dextran, zinc concentration in the liver also increased transitionally after both injections and the time-course of the hepatic zinc level in dextran sulfate showed a close resemblance to that of the calcium one.