Paul Nguyen

Cardiovascular effects of caffeine and nifedipine

Because caffeine and nifedipine may have opposing effects on intracellular calcium concentration, a possible interaction between these agents on blood pressure and heart rate was examined. With a randomized, double‐blind, crossover design, 10 normal, caffeine‐abstaining subjects received caffeine, 300 mg, or placebo followed by nifedipine, 10 mg, or placebo. Caffeine increased blood pressure, whereas nifedipine reduced it and caused a reflex increase in heart rate. With caffeine pretreatment, nifedipine decreased blood pressure significantly more than with placebo pretreatment. However, nifedipine reduced blood pressure to the same absolute level on both the caffeine and placebo pretreatment days. The reflex increase in heart rate after nifedipine was not affected by prior caffeine or placebo administration. Caffeine pretreatment does not alter the cardiovascular responses to nifedipine but the pressor effect of caffeine is completely reversed by subsequent nifedipine administration.

Highly Strained Metallocenophanes: Synthesis and Ring-Opening of Sulfur-, Selenium- and Boron- Bridged [1]Ferrocenophanes

Abstract The limits of cyclopentadienyl ring-tilting in [l]ferrocenophanes are explored with the incorporation of group 16 elements and a first row element. In this paper the synthesis and ring-opening polymerisation (ROP) behaviour of highly strained chalcogen-and boron- bridged [l]ferrocenophanes will be described.

The first [2]cobaltocenophane and [2]metallocenophanium salts

A tetramethylethylene bridged ferrocene 1 and cobaltocene 3 are synthesised in two steps from 2-tert-butyl-6,6-dimethylfluvene. Both can be oxidised to the corresponding cations, 2 and 4, the single-crystal X-ray structures of which have been determined.

Unusual Chemistry of Hybrid Borazine-Phosphazene Rings and Strained [1]Ferrocenophanes

Abstract Very few examples of rings constructed of boron, phosphorus and nitrogen are known. In this paper some unusual chemistry of these species and recent studies of [l]ferrocenophanes will be described.