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Biomedical subjects

J Penfold

Publications and source records attributed to J Penfold.

41 records · Page 3Linked to original sources
PubMed1990

Specular reflection of neutrons at phospholipid monolayers. Changes of monolayer structure and headgroup hydration at the transition from the expanded to the condensed phase state.

The specular neutron reflection technique has been applied for the first time to study the structure and head group hydration of a phospholipid monolayer (dimyristoylphosphatidylcholine containing negatively charged phospholipids) in the condensed and expanded state. By variation of the contrast of the subphase to that of the air it is shown that at the transition from the condensed to the expanded state the carboxyl bonds of the glycerol backbone are hydrated leading to a strong structural change of the headgroup. The total monolayer thickness in the condensed state is 22.5 +/- 1 A (tilt angle 32 +/- 6 degrees) and decreases to 19.5 +/- 1 A in the expanded state. The mean molecular volume increases from 1190 +/- 50 A3 to 1250 +/- 50 A3.

Deuterium↗
PubMed1981

Insulin infusion for diabetic children.

Low-dose insulin infusion was used successfully in the management of 10 diabetic children aged 3.5 to 16.7 years (five ketoacidosis, four with insulin refractory hyperglycaemia, and one during elective surgery). The mean duration of infusion was 33 hours, with a mean infusion rate of 2.9 units/h for the ketotic subjects, and 2.6 units/h for those requiring stabilization. The over-all mean hourly rate per kg body weight was 0.074 units. Extension of the infusion time beyond that needed for the immediate correction of the hyperglycaemia and/or ketoacidosis enabled the smooth transition to a subcutaneous insulin regimen. Low-dose insulin infusion has introduced a new dimension of flexibility in the management of diabetes in the paediatric age group; the technique can be used to break the cycle of insulin-refractoriness as well as to reverse ketoacidosis. The surgeon can also anticipate a more predictable control of blood glucose level during major surgery when a continuous insulin infusion regimen is used.

Adolescent↗