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Biomedical subjects

G Meijer

Publications and source records attributed to G Meijer.

26 records · Page 2Linked to original sources

Pulsed ENDOR studies at 95 GHz of the triplet state of 13C60

Fully 13C-enriched C60 has been investigated by pulsed electron-nuclear double-resonance (ENDOR) spectroscopy at W-band frequency at 1.2 K. For molecular C60 the ENDOR spectra reflect the distortion of the molecule upon triplet excitation, and the fine-structure parameter D is found to be negative. For a single crystal of C60 the ENDOR spectra characterize the triplet excitation as delocalized over a pair of neighboring C60 molecules. Copyright 1998 Academic Press.

Journal Article↗

Factor VIIa response to a fat-rich meal does not depend on fatty acid composition: a randomized controlled trial.

A fat-rich meal increases activated factor VII (FVIIa), but it is not clear whether this increase depends on the fatty acid composition of the meal. Therefore, we studied the FVIIa response to fat-rich meals with different fatty acid composition in a randomized controlled crossover trial and investigated whether this response is mediated by an increase in serum triglycerides. Elderly women (> 60 years, n=91) received on separate days four different fat-rich breakfasts (50 energy percent [en%] of fat) and a control breakfast (1.5 en% fat; crossover). The fat-rich breakfasts differed in fatty acid composition: one rich in palmitic acid (21.7 g), one in stearic acid (18.6 g), and the other two in linoleic and linolenic acid-one with a ratio 3:1 (12.5/3.9 g) and the other with a ratio of 15:1 (18.8/1.2 g). At 8 AM before the breakfast (fasting) and at 1 and 3 PM, blood samples were taken, in which FVIIa and serum triglycerides were measured. FVIIa response to the fat-rich meals ranged from 11.6 mU/mL (95% confidence interval: 8.3,14.9) on the stearic meal to 15.9 mU/mL (12.0,19.8) on the linoleic/linolenic 15:1 meal at 1 PM and from 14.9 mU/mL (10.6,19.2) to 21.1 mU/mL (16.6,25.6) for the same meals at 3 PM. The responses did not differ between the fat-rich meals. After the control breakfast, FVIIa decreased, with 6.3 mU/mL (3.9,8.7) at 1 PM and 8.7 mU/mL (6.3,11.1) at 3 PM. The triglyceride response was lower after both linoleic/linolenic rich breakfasts compared with the palmitic and stearic breakfast (P<.05) and was not associated with the FVIIa response at any of the blood sampling occasions. The results of this study show that the response of FVIIa to a fat-rich meal is independent of its fatty acid composition and is not mediated by serum triglycerides.

Aged↗

Determination of the stability of diluted allergen extracts using a concentration step prior to EAST inhibition.

BACKGROUND: Generally the stability of diluted allergen extracts, as used for skin testing, provocation testing and immunotherapy can not be measured using a normal enzyme allergosorbent test (EAST) inhibition method. OBJECTIVE: The aim of this study was to determine the stability of diluted allergen extracts using an ultrafiltration step prior to the standard EAST inhibition procedure, in which the allergen extract was concentrated 100-fold. METHODS: This concentration procedure was validated for Dermatophagoides pteronyssinus, timothy pollen, birch pollen and cat dander extracts and used in a stability study in which three batches were stored for 1 year at 6 degrees C and 25 degrees C. RESULTS: There was no difference in relative potency before and after concentration of birch and timothy pollen extracts. D. pteronyssinus and cat dander extracts showed a significant decrease of 25% and 35% of the relative potency after concentration. The mean coefficient of variation of 12 determinations of the stability study was 11.8%. CONCLUSION: For all allergens the 30 BU/mL or approximately 0.00025 mg/mL solution was stable for 12 months at both temperatures, except for D. pteronyssinus which declined rapidly at 25 degrees C.

Allergens↗