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Biomedical subjects

P J McCullagh

Publications and source records attributed to P J McCullagh.

28 records · Page 2Linked to original sources
PubMed1985

A preliminary investigation into the nature of shock absorbency in synthetic sports materials.

Tests were conducted on three athletic shoe midsole materials and on three synthetic sports surfaces. All specimens were found to absorb energy when loaded. For a specific maximum load the amount of energy absorbed by each material was found to decrease as the load application rate increased. The materials exhibited different capacities to dissipate energy under the application of the same impulse. This may be a consideration for the injury protection afforded. The development of rheological models from the results of the tests aided an explanation of how force is resisted and energy absorbed by synthetic sports materials. Their shock absorbing properties were associated with the rheological elements of elasticity and viscosity.

Absorption↗
PubMed1981

Studies on the apoproteins of rat lymph chylomicrons: characterization and metabolism of a new chylomicron-associated apoprotein.

The apoprotein composition of rat lymph chylomicrons and very low density lipoprotein (VLDL) was investigated following isolation and purification by preparative gel electrophoresis. The medium molecular weight apoproteins in the 27,000-60,000 range were characterized by electrophoretic mobility, immunochemical identification, amino acid composition, and molecular weight determination. In addition to three previously identified apoproteins, A-I, E, and A-IV, present in both rat serum high density lipoproteins (HDL) and lymph chylomicrons, a fourth peptide of molecular weight 59,000 was always a consistent major component of lymph VLDL washed free of serum protein contaminants by repeated ultracentrifugation. The protein formed complexes with phosphatidylcholine vesicles, was amphipathic in nature, and, when injected into rats, became associated with serum HDL and lymph chylomicrons. It was removed from chylomicrons after gel filtration through agarose columns but not after repeated ultracentrifugation; it differed slightly in amino acid composition and did not show immunochemical identity against antisera to any other apoprotein. The results of in vivo studies suggest that the protein preferentially associates with lymph chylomicrons and thus may play some important role in the metabolism of exogenous triglyceride transport. Since A-I, A-II, and A-IV apoproteins are also integral components of lymph chylomicrons, we suggest that the protein be designated A-V apoprotein. The distribution of A-I, E, A-IV, and A-V in serum HDL and lymph VLDL was approximately 54, 10, 12, and 0%, and 22, 3, 19, and 22%, prospectively.

Amino Acids↗
PubMed1970

The abrogation of sheep erythrocyte tolerance in rats by means of the transfer of allogeneic lymphocytes.

Whereas the transfer of lymphocytes from normal syngeneic donors fails to abrogate tolerance of sheep erythrocytes in rats, lymphocytes from allogeneic donors are effective. When tolerance is abrogated in this situation, the hemolysin-forming cells are predominantly of host origin. Immunological interaction between transfused lymphocytes and host cells is a prerequisite for the abrogation of tolerance. From the time required for abrogation to occur after transfer of the allogeneic cells, it is suggested that tolerance of sheep erythrocytes in rats represents the repression of a specific reactivity in cells rather than the elimination or irreversible inactivation of reactive cells. This explanation implies the existence of specifically tolerant cells.

Animals↗
PubMedDate not supplied

Computer-assisted measurement of peripheral blood flow.

An automated system for the measurement of peripheral blood flow using venous occlusion plethysmography based on the low-cost Apple II microcomputer, together with purpose-built compressor unit and data acquisition interface, has been developed. The computer performs the dual role of controlling the timing of inflation and deflation of the occluding cuffs and recording the resulting increase in limb circumference. Ten 8 s epochs of data are acquired and analysed per session. Flow rate is computed using a least squares fit between 0.5 and 4.0 s after cuff inflation, giving on-line indication of blood flow. Venous capacitance and digital systolic pressure may be measured using additional algorithms. The system has been used for the investigation of circulatory disorders and in the assessment of drugs acting on the peripheral circulation.

Blood Pressure↗