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Biophysical aspects of microsphere engulfment by human neutrophils
;.bstracts THE EFFECTS OF MACROTEXTURING UPON PROXIMAL CEMENT MANTLE STRAINS SURROUNDING A THR FEMORAL COMPONENT: AN IN VITRO STRAIN GAGE STUDY Michael Bushelow and Thomas Crippen Howmedica, Div. Pfizer Hospital Products Group, Inc. Rutherford, New Jersev 07070. USA. An -in.vitro strain gage study was undertaken to determine the effects of macrotexturing the proximal anterior and posterior surfaces of a THR femoral component. A textured and a satin finished component were each coated with a thin layer of bone cement along their proximal medial and lateral surfaces and stacked rectangular rosette strain gages were attached to the coated areas. The components were implanted in embalmed, human, adult cadaver femurs. Various load conditions were simulated. Though strain readings varied from bone to bone, in all cases the textured stem showed lower medial and lateral proximal tensile cement mantle strains. When the strain gage readings were extrapolated to a load of four times body weight (2670-3560 NJ strain readings around the satin finished stem were as high as 3000 microstrain. Strain readings around the textured stem never exceeded 800 microstrain.
SESSION 10. MECHANICAL PROCESSES SMALL ORGANISMS
IN CELLS AND
BIOPHYSICAL ASPECTS OF MICROSPHEREENGULFMENTBY HUMANNEUTROPHILS Scott I. Simon and Geert W. Schmid-Schkbein AMES-Bioengineering - San Diego, La Jolla, California 92093, USA University of California The conservation of membrane area during phagocytosis of indigestible latex microspheres by human neutrophils was investigated. When a neutrophll internalizes a microsphere plasma membrane is removed and the cell volume increases. Thus the process is limited to a finite number of microspheres which can be internalized. Based on the initial cell volume and membrane area a prediction of the number of internalized microspheres was made and compared with the experiments. The results show that unless endocytosis of membrane covered lysosomes is accounted for, the observed numbers exceed the prediction, but with lysosomal release the prediction falls within experimental error. These results show, that the available membrane area is an important limiting factor in phagocytosis. Supported
In part
by NHLBI Grant
HL-10881
ELASTICITY OF THE ZONA PELLUCIDA OF THE MAMMALIAN EGG L.Y. Cheng', E.Z. Drobnis' and D.F. Katz' 'Failure Analysis Assoc., Palo Alto, CA and 'Dept of Obstetrics of California, Davis, CA 95616, USA
and Gynecology,
University
The mammalian egg is encapsulated by an acellular, glycoprotein shell, termed the zona pellucida. The zona functions to limit access to the egg to a single sperm, and to protect the egg and early embryo during transport through the oviduct to the uterus. Mechanical zona properties play a paramount role in these functions, but little previously has been We conducted microcapillary suction experiments in which local zona known about them. deformation into the capillary was measured in relation to suction pressure. The data were analyzed numerically, using a finite amplitude solution of the equations of elasticity. This allowed for large deformations and the thick shell nature of the zona. We found some for the pig, E = 300 kdyne/cm*; for the hamster and species variation in zona elasticity: Following fertilization, the zona became less elastic, by mouse, E = 100 kdyne/cm'. These mechanical changes may approximately 25% in the hamster and by 100% in the mouse. (Supported by serve to help the zona achieve its post-fertilization biological functions. NIH grant HD12971).
SESSION 10. MECHANICAL PROCESSES SMALL ORGANISMS
IN CELLS AND
BIOPHYSICAL ASPECTS OF MICROSPHEREENGULFMENTBY HUMANNEUTROPHILS Scott I. Simon and Geert W. Schmid-Schkbein AMES-Bioengineering - San Diego, La Jolla, California 92093, USA University of California The conservation of membrane area during phagocytosis of indigestible latex microspheres by human neutrophils was investigated. When a neutrophll internalizes a microsphere plasma membrane is removed and the cell volume increases. Thus the process is limited to a finite number of microspheres which can be internalized. Based on the initial cell volume and membrane area a prediction of the number of internalized microspheres was made and compared with the experiments. The results show that unless endocytosis of membrane covered lysosomes is accounted for, the observed numbers exceed the prediction, but with lysosomal release the prediction falls within experimental error. These results show, that the available membrane area is an important limiting factor in phagocytosis. Supported
In part
by NHLBI Grant
HL-10881
ELASTICITY OF THE ZONA PELLUCIDA OF THE MAMMALIAN EGG L.Y. Cheng', E.Z. Drobnis' and D.F. Katz' 'Failure Analysis Assoc., Palo Alto, CA and 'Dept of Obstetrics of California, Davis, CA 95616, USA
and Gynecology,
University
The mammalian egg is encapsulated by an acellular, glycoprotein shell, termed the zona pellucida. The zona functions to limit access to the egg to a single sperm, and to protect the egg and early embryo during transport through the oviduct to the uterus. Mechanical zona properties play a paramount role in these functions, but little previously has been We conducted microcapillary suction experiments in which local zona known about them. deformation into the capillary was measured in relation to suction pressure. The data were analyzed numerically, using a finite amplitude solution of the equations of elasticity. This allowed for large deformations and the thick shell nature of the zona. We found some for the pig, E = 300 kdyne/cm*; for the hamster and species variation in zona elasticity: Following fertilization, the zona became less elastic, by mouse, E = 100 kdyne/cm'. These mechanical changes may approximately 25% in the hamster and by 100% in the mouse. (Supported by serve to help the zona achieve its post-fertilization biological functions. NIH grant HD12971).