A glucomannan from Arum korolkovii
SummaryA glucomannan has been isolated from the tubers ofArum korolkovii Regel. It has been shown that the polysaccharide contains O-acetyl groups and consists mainly of (1 → 4)-β-linked aldohexopyranose units of glucose and mannose in a ratio of 1:1.6. The nonreducing ends of the glucomannan are glucose residues, and branching is localized at C2 and C3 of mannose.
Acetyl Groups in Native Glucomannan from Easter Lily Bulbs
Glucomannan has been extracted with water from several plants and purified via a copper complex using Fehling's solution.1-8) It is well-known, however, that the resulting polysaccharide becomes insoluble in water. This is the reason why biochemical research on polysaccharides is difficult, and it seems doubtful whether the insoluble polysaccharide is native. In this report we have attempted to compare the glucomannan compounds extracted and purified by two different procedures from Easter lily bulbs and to investigate the cause of the insolubility. Glucomannan was extracted from commercial bulbs of Easter lily (Lilium longiflorum Thunb var. "Georgia." All bulbs were at the dormant stage.) by the following two procedures. One was the conventional method with Fehling's solution (yield; 1.78% from fresh scales)'1 The other was a procedure not involving Fehling's solution, as described below. Fresh scales (20 g) were homogenized in a mortar with 20 volumes of dist. water. After centrifugation, an equal volume of ethanol was added to the supernatant. The precipitate was dis solved into 100 ml of dist. water. The solution, after dialysis against 0.01 M phosphate buffer (pH 7.3) or dist. water, was applied to a DEAE-cellulose column
How to interpret surveys in medical research: A practical approach
Surveys are being used increasingly in health-care research to answer questions that may be difficult to answer using other methods. While surveys depend on data that may be influenced by self-report bias, they can be powerful tools as physicians seek to enhance the quality of care delivered or the health care systems they work in. The purpose of this article is to provide readers with a basic framework for understanding survey research, with a goal of creating well-informed consumers. The importance of validation, including pretesting surveys before launch, will be discussed. Highlights from published surveys are offered as supplementary material. Was the survey well designed? Was the sample appropriate and the response rate adequate? And do the data support the conclusions?