PubMed · 118598
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G Neuhäuser. 1979-11-30. [Sphingolipidoses].. https://pubmed.ncbi.nlm.nih.gov/118598/
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The evidence that small GTPases of the Rab family are regulators of vesicle traffic which can influence various cell functions prompted us to investigate the potential role of one of these proteins, Rab5a, in human neutrophils. In this paper we show that a large amount of Rab5a is present in the cytosol of peripheral blood mature neutrophils. The remaining protein was found to be membrane and azurophilic granule associated. Upon neutrophil challenge with PMA for 10 min the amount of membrane-associated Rab5a was upregulated while the cytosolic content of the protein concomitantly decreased. These findings support the hypothesis that Rab5a could be involved in the mechanism of neutrophil activation by modulating the rate of endocytosis and/or vesicle fusion.
Proteinase inhibitors confine the activity of proteolytic enzymes of inflammatory cells, but fail to protect substrates in the immediate pericellular zone. We report quantitative imaging that demonstrates discrete, evanescent, quantized proteolytic events attributable to the release of single azurophil granules from neutrophils. The images provide information about the dynamics of this nonequilibrium system, which is characterized by overwhelmingly high local concentrations of enzymes that rapidly dissipate. With physiologic concentrations of extracellular human leukocyte elastase inhibitors (32.8 microM), the radii of the unit proteolytic events are 1.32 microm (approximately 8 times the radius of the azurophil granule) and are inversely and nonlinearly related to the concentration of proteinase inhibitor that is present in the bathing medium. We have obtained identical results with alpha1-antitrypsin, alpha2m, recombinant secretory leukocyte proteinase inhibitor, and ICI 200,355, and we have found that phagocyte-derived oxidants are not required for the genesis of this catalytic activity. Our results reveal that the enzyme:inhibitor ratio is the primary delimiter of quantized proteolysis in the local microenvironment.
OBJECTIVE: Our goal was to determine any ultrastructural anomalies in an oocyte from a patient with a history of polyspermy. RESULTS: Ultrastructural observations of the cortical ooplasm of several oocytes from each of three control patients showed a large population of intact cortical granules. Conversely, one oocyte from a patient with repeated polyspermic fertilization contained a relative paucity of granules in the cortex. Quantitative analysis of the cortices of control oocytes indicated that there were 17.02 +/- 0.52 cortical granules present per measured field of view, compared with 4.40 +/- 2.92 granules per field in the other oocyte. CONCLUSIONS: The presence of sufficient cortical granules is necessary for normal (monospermic) fertilization to occur. When contrasted to the cortical granule population of oocytes from several control patients, the cortex of one oocyte from the other patient showed few of these organelles. Therefore, the absence of a sufficient number of granules may have precluded normal fertilization from occurring in the eggs of this patient.