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M Willinger

Publications and source records attributed to M Willinger.

25 records · Page 2Linked to original sources
PubMed1981

Neuronal differentiation in cultures of weaver (wv) mutant mouse cerebellum.

In the present study we report for the first time a weaver (wv) gene dose effect on neuron survival and neurite formation in vitro. Dissociated cerebellar cells from postnatal 7- and 8-day-old normal (+/+), heterozygous weaver (+/wv) and homozygous weaver (wv/wv) mice were cultured as monolayers on poly-L-lysine coated glass. Cell death occurred rapidly in wv/wv cultures. Cell counts showed that less than 20% of the total neurons and neuronal precursors (identified by "birthday" radiolabeling techniques) survived by Day 3. Cell death was less extensive in +/wv cultures with 65% of the total neurons and 80% of the precursors surviving by Day 3. In contrast to wv/wv cultures, younger neurons survive better than the total population in +/wv cultures. The impairment of neurite formation over the first week is also proportional to the number of mutant genes as shown by quantitation of (a) the percentage of cells with neurites; (b) the percentage of cells with neurites of a given length class ith time; (c) the lengths of the longest process formed per cell. The mean longest neurite lengths obtained by computer digitization at 6 days in vitro were 41.8, 26.8, and 9.0 micron for +/+, +/wv, and wv/wv granule cells, respectively.

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PubMed1979

Fate of surface proteins of rabbit polymorphonuclear leukocytes during phagocytosis. I. Identification of surface proteins.

To study the fate of external membrane proteins during phagocytosis, rabbit peritoneal neutrophils were labeled by enzymatic iodination. Iodine was incorporated into at least 13 proteins ranging in size from approximately 250,000 to 18,000 daltons as judged from autoradiography of gels after SDS-polyacrylamide gel electrophoresis of labeled cells. The major contractile proteins of neutrophils, actin and myosin, were not labeled when intact cells were iodinated but were labeled when homogenates of these cells were iodinated. Nine of the iodinated proteins were released by mild protease treatment of intact cells. A plasma membrane-rich fraction was isolated by density centrifugation. This fraction was enriched at least 10-fold for lactoperoxidase-labeled acid-insoluble proteins. It was enriched to the same extent for the presence of iodinated wheat germ agglutinin that had been bound to intact cells at 4 degrees C before homogenization. Analysis of SDS-polyacrylamide gel electrophoresis revealed that the proteins of this fraction were predominantly of high molecular weight. However, only 8 of the 13 proteins iodinated on intact cells were found in this fraction. The remaining five were enriched in a dense fraction containing nuclei, intact cells, and membranous vesicles, and may represent a specialized segment of the neutrophil cell surface.

Animals↗
PubMed1979

Fate of surface proteins of rabbit polymorphonuclear leukocytes during phagocytosis. II. Internalization of proteins.

The distribution of surface proteins during phagocytosis by rabbit peritoneal polymorphonuclear leukocytes was studied to determine whether the proteins of the phagocytic vesicles of these differentiated cells were representative of the entire set of plasma membrane proteins. Phagocytosis of bovine serum albumin-diisodecylphthalate emulsion by lactoperoxidase-iodinated rabbit neutrophils was linear over 15-20 min at a rate of 96 microgram oil/min/mg cell protein. This rate was similar to that of unlabeled cells. Incorporation of cell-associated free iodine by endogenous myeloperoxidase during phagocytosis was inhibited by 1 mM cyanide, which had no effect on the rate of particle uptake. The surface of intact neutrophils contained at least 13 iodinated proteins distinguishable by polyacrylamide gel electrophoresis followed by autoradiography. Isolated phagosomes were deficient in six of these proteins. The plasma membrane fraction of these cells was missing five of these same proteins which, however, were enriched in a dense surface fraction (Willinger, M., and F. R. Frankel. J. Cell Biol. 82: 32-44). When experimental conditions were reversed, and the PMNs were labeled after phagocytosis, these five proteins remained on the cell surface, while at least three of the major proteins found on resting cells were depleted. Incubating the cells with colchicine, which has been shown to affect the distribution of some plasma membrane constituents during phagocytosis, had no effect on the distribution of surface proteins in our system. These results indicate that a nonrandom interiorization of lactoperoxidase-labeled surface proteins of polymorphonuclear leukocytes occurs during phagocytosis.

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PubMedDate not supplied

Factors associated with the transition to nonprone sleep positions of infants in the United States: the National Infant Sleep Position Study.

CONTEXT: Studies have demonstrated strong associations between the prone sleep position (on the stomach) and sudden infant death syndrome (SIDS). In 1992, the American Academy of Pediatrics recommended that infants be placed to sleep laterally (on their side) or supine (on their back) to reduce SIDS risk, and in 1994, the national public education campaign "Back to Sleep" was launched. OBJECTIVE: To determine the typical sleep position of infants younger than 8 months in the United States, the changes that occurred after these recommendations, and the factors associated with the placement of infants prone or supine. DESIGN: Annual nationally representative telephone surveys. SETTING: The 48 contiguous states of the United States. PARTICIPANTS: Nighttime caregivers of infants born within the last 7 months between 1992 and 1996. Approximately 1000 interviews were conducted per year. MAIN OUTCOME MEASURES: The position the infant was usually placed in for sleep, and the position the infant was most commonly found in when checked during the night's sleep. RESULTS: Ninety-seven percent of respondents in each wave of the survey usually placed their infant to sleep in a specific position. Infants were placed in the prone position by 70% of caregivers in 1992, prior to the campaign, but only 24% in 1996. Supine and lateral placements increased during this time period, from 13% in 1992 to 35% in 1996 and from 15% in 1992 to 39% in 1996, respectively. Significant predictors of prone placement included maternal race reported as black (odds ratio [OR], 2.34; 95% confidence interval [CI], 1.68-3.26), mother's age 20 to 29 years (OR, 1.28; 95% CI, 1.09-1.50), region reported as the mid-Atlantic (OR, 1.41; 95% CI, 1.12-1.78) or southern states (OR, 1.47; 95% CI, 1.22-1.70), mothers with a previous child (OR, 1.68; 95% CI, 1.43-1.97), and infants younger than 8 weeks (OR, 0.63; 95% CI, 0.46-0.85). Infants aged 8 to 15 weeks were significantly more likely to be placed nonprone over time compared with the other age groups. Most of the risk factors for prone were significantly related in the opposite direction to supine placement. CONCLUSIONS: The prevalence of infants placed in the prone sleep position declined by 66% between 1992 and 1996. Although causality cannot be proved, SIDS rates declined approximately 38% during this period. To achieve further reduction in prone sleeping, efforts to promote the supine sleep position should be aimed at groups at high risk for prone placement.

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