ABSTRACT
BACKGROUND: Homeopathic drugs even with dilutions beyond 10(23) (high potencies) are frequently used, although their working mechanism is still unknown. Curative information preserved in solvent structure is postulated to exert biologic effects. OBJECTIVE: The objective was to test for a stimulating or inhibiting effect of high potencies of the homeopathic remedy HgCl2 (Mercurius corrosivus) on two sugar hydrolases. METHODS: High potencies were produced using stepwise dilution plus shaking. Controls included potentized solvent (aqua bidestillata), equimolar dilutions without shaking, and enzyme-free references. Tested were potencies with dilution factors 1:200 (CC) on diastase extract from winter barley, and 1:100 (C) on alpha-amylase from hog pancreas. Enzyme activity was colorimetrically determined by Lugol's iodine-starch reaction. RESULTS: An inhibiting effect of HgCl2 on enzyme activities was observed only in low potencies and dilutions. Statistically significant differences between potencies and controls were not found in randomized and blinded experiments. CONCLUSIONS: This experimental design provided independent reproducible results of cell-free in vitro assays. However, it did not indicate an effect of potentized HgCl2 on hydrolases. Demonstrating potency effects may require additional experimental features.
Subject(s)
Amylases/drug effects , Homeopathy/methods , Mercuric Chloride/pharmacology , Solutions/analysis , alpha-Amylases/drug effects , Analysis of Variance , Chemistry, Pharmaceutical , Dose-Response Relationship, Drug , Drug Compounding/methods , In Vitro Techniques , Mercury Compounds/pharmacology , Reproducibility of Results , Research Design/standardsABSTRACT
Previous studies have reported that insect cell lines lack the capacity to generate endogenously the nucleotide sugar, CMP-Neu5Ac, required for sialylation of glycoconjugates. In this study, the biosynthesis of this activated form of sialic acid completely from endogenous metabolites is demonstrated for the first time in insect cells by expressing the mammalian genes required for the multistep conversion of endogenous UDP-GlcNAc to CMP-Neu5Ac. The genes for UDP-GlcNAc-2-epimerase/ManNAc kinase (EK), sialic acid 9-phosphate synthase (SAS), and CMP-sialic acid synthetase (CSAS) were coexpressed in insect cells using baculovirus expression vectors, but the CMP-Neu5Ac and precursor Neu5Ac levels synthesized were found to be lower than those achieved with ManNAc supplementation due to feedback inhibition of the EK enzyme by CMP-Neu5Ac. When sialuria-like mutant EK genes, in which the site for feedback regulation has been mutated, were used, CMP-Neu5Ac was synthesized at levels more than 4 times higher than that achieved with the wild-type EK and 2.5 times higher than that achieved with ManNAc feeding. Addition of N-acetylglucosamine (GlcNAc), a precursor for UDP-GlcNAc, to the media increased the levels of CMP-Neu5Ac even more to a level 7.5 times higher than that achieved with ManNAc supplementation, creating a bottleneck in the conversion of Neu5Ac to CMP-Neu5Ac at higher levels of UDP-GlcNAc. The present study provides a useful biochemical strategy to synthesize and enhance the levels of the sialylation donor molecule, CMP-Neu5Ac, a critical limiting substrate for the generation of complex glycoproteins in insect cells and other cell culture systems.