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Biomedical subjects

Roger Taylor

Publications and source records attributed to Roger Taylor.

At least 19 recordsLinked to original sources
PubMed2004

C2 C70F38 is aromatic, contains three planar hexagons, and has equatorial addends.

Single crystal X-ray analysis shows the main (C(2)) isomer of C(70)F(38) to contain three planar delocalised aromatic hexagons (two equivalent and one centred on the C(2) axis), together with seven C[double bond, length as m-dash]C bonds (three pairs and one straddling the C(2) axis); C(70)F(38) is the first high addition level [70]fullerene derivative to be fully characterised, is the first to have equatorial addends, and is calculated to have high stability.

Journal Article↗
PubMed2004

Electrophilic aromatic substitution by the fluorofullerene C60F18.

The FeCl3-catalysed arylation of C60F18 gives tri-substituted compounds C60F15Ar3, where Ar=phenyl, 4-tolyl, 4-methoxyphenyl, 4-phenoxyphenyl, 4-chlorophenyl, 3,4-dichlorophenyl, 2-biphylenyl and 2-fluorenyl, together with some bis- and mono-substituted product. Bis-substitution was achieved with biphenylene and fluoranthene, and mono-substitution with biphenylene (2-position), pyrene (1-position), and naphthalene (1- and 2-positions); the tris-phenyl and tris-biphenylene derivatives are fluorescent. The 2-naphthyl substituent freely rotates at 328 K, whereas rotation of the 1-naphthyl substituent is prevented by interaction of the peri-hydrogen atom with fluorine. The 1-naphthyl derivative eliminates a molecule of HF during EI mass spectrometry, whilst the 2-naphthyl derivative eliminates HF and all fluorenes to give a naphthaleno[60]fullerene. The reaction rate is relatively unaffected by electron supply in the aryl rings, but no product was obtained with benzotrifluoride which defines the lower reactivity limit. The low discrimination between aromatics makes it possible to isolate derivatives having different aryl groups attached to the cage. Reactions occur mainly when the reagent solutions (or solutions in 1,2-dichlorobenzene) are evaporated to dryness. In most FeCl3-catalysed reactions, unreacted C60F18 was recovered, more if the less effective SnCl4 was used as a catalyst; use of AlCl3 resulted in polyarylation and degradation of the C60F18. The structure of C60F17(1-biphenylyl) was confirmed by single-crystal X-ray analysis. Reaction of C60F18 with perylene/FeCl3/o-dichlorobenzene gave red fluorescent "tagliatelli"-like threads (up to 1 cm long) of self-assembled pi-stacked tetrachloroperylene arising from chlorination by FeCl3.

Crystallography, X-Ray↗
PubMed2004

Effect of exercise training on endothelium-derived nitric oxide function in humans.

Vascular endothelial function is essential for maintenance of health of the vessel wall and for vasomotor control in both conduit and resistance vessels. These functions are due to the production of numerous autacoids, of which nitric oxide (NO) has been the most widely studied. Exercise training has been shown, in many animal and human studies, to augment endothelial, NO-dependent vasodilatation in both large and small vessels. The extent of the improvement in humans depends upon the muscle mass subjected to training; with forearm exercise, changes are restricted to the forearm vessels while lower body training can induce generalized benefit. Increased NO bioactivity with exercise training has been readily and consistently demonstrated in subjects with cardiovascular disease and risk factors, in whom antecedent endothelial dysfunction exists. These conditions may all be associated with increased oxygen free radicals which impact on NO synthase activity and with which NO reacts; repeated exercise and shear stress stimulation of NO bioactivity redresses this radical imbalance, hence leading to greater potential for autacoid bioavailability. Recent human studies also indicate that exercise training may improve endothelial function by up-regulating eNOS protein expression and phosphorylation. While improvement in NO vasodilator function has been less frequently found in healthy subjects, a higher level of training may lead to improvement. Regarding time course, studies indicate that short-term training increases NO bioactivity, which acts to homeostatically regulate the shear stress associated with exercise. Whilst the increase in NO bioactivity dissipates within weeks of training cessation, studies also indicate that if exercise is maintained, the short-term functional adaptation is succeeded by NO-dependent structural changes, leading to arterial remodelling and structural normalization of shear. Given the strong prognostic links between vascular structure, function and cardiovascular events, the implications of these findings are obvious, yet many unanswered questions remain, not only concerning the mechanisms responsible for NO bioactivity, the nature of the cellular effect and relevance of other autacoids, but also such practical questions as the optimal intensity, modality and volume of exercise training required in different populations.

Endothelium, Vascular↗
PubMed2004

Day-case surgery.

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Ambulatory Surgical Procedures↗
PubMed2004

Process power.

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Data Interpretation, Statistical↗
PubMed2004

Methylation of [76]fullerene and [84]fullerenes; the first oxahomo derivatives of a higher fullerene.

Methylation of [76]fullerene by reaction with Al-Ni alloy/NaOH followed by quenching of the intermediate anions with methyl iodide gives a mixture of methylated and methylenated products together with oxide derivatives. The major derivatives are five isomers of C(76)Me(2)(one of C(s) symmetry due to 1,6-C(76)Me(2)) and C(76)(CH(2))(n)(n= 2-4), together with corresponding mono-oxides. The single line (1)H NMR spectrum of mono-oxide C(76)Me(2)O shows it is an oxahomofullerene (ether) the first example derived from [76]fullerene, oxygen being inserted between the CMe groups in 1,6-C(76)Me(2)giving a product of C(2) symmetry. The probable structures of the unsymmetrical dimethyl derivatives have been deduced from heats of formation calculated by AM1 and density functional methods. Bis-oxide C(76)Me(4)O(2) is the first bis oxahomo[76]fullerene to be isolated and gives two equal-intensity lines in the (1)H NMR spectrum showing that it must also have C(2) symmetry; probable structures are considered. Methylation of [84]fullerene takes place less readily and only four C(84)Me(2) derivatives were isolated, two of them in quantities sufficient to show the symmetries as C(1), and either C(2) or C(s).

Journal Article↗
PubMed2004

Caesarean rates.

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Cesarean Section↗
PubMed2004

Delayed discharge.

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Arthroplasty, Replacement, Hip↗
PubMed2004

Pick of the crop.

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Choice Behavior↗