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Biomedical subjects

R W Baker

Publications and source records attributed to R W Baker.

At least 73 records · Page 4Linked to original sources
PubMed1978

Gel filtration of phthalate esters.

Calibration of the gel-filtration system polystyrene beads-benzene is effected in terms of the molecular weights of solutes without using a void volume indicator. Correction for dead volumes is made by incorporating in the loads a dye producing a peak of accurately known elution volume to serve as reference point on a stripchart absorption diagram of column effluent. The calibrated column separates small amounts of plasticizer phthalate esters from excess of lipids extracted from biological materials, providing evidence of identity in samples sufficiently pure for estimation by gas chromatography. Further purification can, where necessary, be achieved quantitatively by high-performance liquid chromatography on silicic acid with 2% (v/v) diisopropyl ether in n-hexane as mobile phase.

Chromatography, Gel↗
PubMed1978

Diethylhexyl phthalate as a factor in blood transfusion and haemodialysis.

Di-2-ethylhexyl phthalate (DEHP), the most frequently occurring plasticiser in medical equipment manufactured from polymers of vinyl chloride, forms about 40% w/w of tubes and containers used for storing blood and for haemodialysis. The plasticiser leaches out into liquids with lipid contents, although it is very sparingly soluble in purely aqueous solutions. On infusion of 2-3 1 of stored blood, up to 200 mg DEHP may be transferred to the patient, while much higher quantities may be given during dialysis, which is moreover often repeated frequently over long periods. The acute toxicity of DEHP is very low (greater than 20 g/kg as LD50 in rats), and the ester is rapidly metabolised to products which are excreted in the urine and bile; chronic toxicity from the levels of dosage obtaining is thus very improbable. Carcenogenicity has never been demonstrable in animals, while teratological effects are of a very low order. Serious acute results observed after transfusion of neonates have not been proved to be caused by DEHP, and might be ascribable to accompanying foreign substances. Atheroma in chronic dialysis subjects is still unexplained, but hepatitis probably caused by diethylphthalate from plastic was resolved when apparatus plasticised by DEHP alone was substituted. The benefits of DEHP appear vastly to outweigh any risks. The status of DEHP as environmental contaminant is noted.

Animals↗
PubMed1976

Peripheral nerve abnormalities related to galactose administration in rats.

Electrophysiological, biochemical, and morphometric observations were made on the peripheral nerves of rats after galactose feeding. Motor nerve conduction velocity was found to be reduced. This was associated with an accumulation of galactitol in the peripheral nerves and a diminution in their myoinositol content. An increased water content and fascicular area, taken in conjunction with a probable increase in the area of the endoneurial spaces, indicated overhydration of the peripheral nerves. Morphometric observations on the myelinated fibre population in the tibial nerve showed no loss of fibres and although both the maximal and the average diameter of the myelinated fibres was slightly less than in age-matched controls, this was insufficient to explain the reduction in conduction velocity. Segmental demyelination was not detected and the relationship between myelin thickness and axon circumference was not altered. Electron microscope observations revealed no ultrastructural changes in the myelinated fibres and, in particular, no abnormalities at the nodes of Ranvier or indication of abnormal hydration of the Schwann cells. The relevance of these findings to the peripheral nerve changes in human and experimental diabetes is discussed.

Animals↗
PubMed1972

Molecular structure of LSD.

The molecular configuration of lysergic acid diethylamide (LSD) in crystals of the iodobenzoate has been determined by using x-ray diffraction techniques. The configuration shows strain and steric hindrance and the conformation is fixed. Some of the implications of this for the hallucinogenic activity of LSD are discussed.

Lysergic Acid Diethylamide↗