The taste, odor and hedonic quality of polyglycerols

Twenty subjects judged the taste and odor intensity and thetaste and odor pleasantness/unpleasantness of five concentrationsof sucrose, glycerol, a commercial triglycerol, a syntheticlinear diglycerol and a synthetic linear triglycerol. Judgmentsof intensity were made using the method of magnitude estimation;judgments of pleasantness/unpleasantness were made using a graphicline scale. Only the two linear polyglycerols had appreciableodor intensity. Both were described as having an ‘acrid’or ‘burnt caramel’ quality. The odor exponent forthe linear triglycerol was extremely high (1.44) and may beattributed to its intensely unpleasant quality. Sucrose wascharacterized solely by sweet taste, glycerol and the commercialtriglycerol by sweet and bitter tastes, the linear diglycerolby sweet, bitter and sour tastes, and the linear triglycerolby bitter and sour tastes. The relationships between perceivedtaste intensity and concentration were well described by powerfunctions, although the slope of the psychophysical functionfor the linear triglycerol was markedly lower than that forthe other compounds. The relative order of taste intensitieswas: linear triglycerol > sucrose > glycerol = lineardiglycerol > commercial triglycerol. Judgments of taste (andodor) pleasantness/unpleasantness showed only sucrose and glycerolto have positive hedonic qualities. All the polyglycerols werejudged unpleasant at all concentrations. Differences in thetaste and odor characteristics of the commercial and synthetictriglycerols were attributed to the commercial product beinga mixture of over 20 compounds. Although the synthetic lineardi- and triglycerols are effective in lowering water activity,these data suggest that more purified crystalline forms mustbe synthesized before they can be used effectively as humectantsfor intermediate moisture foods.     

Progesterone induces transient changes in plasma membrane fluidity of amphibian oocytes during the first meiotic division

Progesterone acts at the surface of the amphibian oocyte to induce resumption of the meiotic divisions. Progesterone binding leads to a transient dose-dependent decrease in the fluidity (increase in order parameter) of the Rana oocyte plasma membrane, which was detected by electron spin resonance in isolated plasma membranes using either 5- or 16-DOXYL stearic acid probes. The 5-DOXYL probe, which inserts into the membrane with the spin label nearest the surface, showed an increase in the order parameter within minutes, a maximum change by 2 h, and a return to control levels by 6 h. The order parameter for the 16-DOXYL probe, which reflects the fluidity deeper within the plasma membrane, increased slowly and remained elevated during the first meiotic division. RU 38486, a synthetic steroid that blocks progesterone receptors, prevents progesterone-induced fluidity changes. These findings indicate that the binding of progesterone to its receptor changes the oocyte plasma membrane structure resulting in a differential decrease in mobility near the membrane surface compared to that deeper in the membrane.     

A possible mechanism for concentrating sodium and potassium in the cell nucleus.

A dynamic, nonequilibrium mechanism is proposed for concentrating both Na+ and K+ in the cell nucleus. The model is consistent with experiment observations and with known properties of cell membranes. This model could explaing the high nucleoplasm to cytoplasm ratios of Na+ and/or K+ reported for liver kidney, thymus, frog skin, ascites cells, and amphibian oocytes.     

Neurological evaluation of chronic headache patients: is laboratory testing always necessary?

A review of records was conducted to examine the utility of doing routine laboratory testing (EEG and skull X rays) versus testing at the discretion of the attending neurologist on patients presenting for the nonpharmacological treatment of chronic headache. A total of 278 patients underwent neurological evaluation as part of a routine assessment prior to beginning self-regulatory treatment for headache. The first 112 subjects received routine laboratory tests of EEG and skull X-ray films. The second set of 166 subjects received laboratory tests only when deemed necessary by the neurologist. The rate of abnormal EEG in chronic headache sufferers was no greater than that found in the normal population, and only one or two potentially serious abnormalities were found on any laboratory test. A higher rate of abnormality was found when the CT scan was used in conjunction with clinical judgment. The majority of clients with abnormal laboratory tests (most of which were mildly abnormal) still saw substantial headache reduction with self-regulatory treatment for chronic headache. The authors suggest that routine laboratory testing may not be necessary and should be left to the discretion of a qualified neurologist.