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Biomedical subjects

M Willinger

Publications and source records attributed to M Willinger.

At least 19 recordsLinked to original sources
PubMed2000

Factors associated with caregivers' choice of infant sleep position, 1994-1998: the National Infant Sleep Position Study.

CONTEXT: The success and simplicity of the 1994 national "Back to Sleep" campaign to reduce sudden infant death syndrome provides an opportunity to study which elements determine whether a behavior will change in the desired direction in response to a public health intervention. OBJECTIVE: To examine sociodemographic characteristics, motivation, and message exposure to ascertain which factors influenced a caregiver's choice of infant sleep position after implementation of the campaign. DESIGN: Annual nationally representative telephone surveys conducted between 1994 and 1998. SETTING: The 48 contiguous United States. PARTICIPANTS: Nighttime caregivers of infants born within the 7 months prior to interview between 1994 and 1998. Approximately 1000 interviews were conducted each year. MAIN OUTCOME MEASURES: The position the infant was usually placed in for sleep, sleep position recommendations received from specific sources, and reasons reported for position choice. RESULTS: Between 1994 and 1998, prone placement declined from 44% to 17% among white infants and from 53% to 32% among black infants. Supine placement increased from 27% to 58% among white infants and from 17% to 31% among black infants. During this period, reports of supine recommendations from at least 1 source doubled from 38% to 79%. From 1995 to 1998, 86% of caregivers who placed the infant prone reported receiving only nonprone recommendations. Infant comfort was given as a reason for prone placement by 82% of these caregivers. In multivariate analysis, physician recommendation of "supine not prone" had the strongest influence and was associated with decreased prone placement (odds ratio [OR], 0.25 [95% confidence interval [CI], 0.16-0.39]) and increased supine placement (OR, 3.37 [95% CI, 2.38-4.76]). Recommendations from all 4 sources (the physician, neonatal nurse, reading materials, and radio/television) further increased the probability of supine placement (OR, 6.01 [95% CI, 4.57-7.90]). Other factors independently associated with increased prone and decreased supine placement included maternal black race, parity of more than 1, and living in a southern or mid-Atlantic state. CONCLUSIONS: According to our study, as of 1998, approximately one fifth of infants were still placed prone, and only half were placed supine. Recommendations of supine placement during infancy by physicians at well-baby checks and by neonatal nursery staff and print and broadcast media have increased the proportion of infants placed supine. Caregiver beliefs regarding perceived advantages of prone sleeping should be addressed to attain further reduction in prone placement.

Choice Behavior↗
PubMed2000

Comparison of apnea identified by respiratory inductance plethysmography with that detected by end-tidal CO(2) or thermistor. The CHIME Study Group.

As part of the Collaborative Home Infant Monitoring Evaluation (CHIME) we compared apnea identified by a customized home monitor using respiratory inductance plethysmography (RIP) with simultaneously recorded polysomnography-acquired nasal end-tidal CO(2) (PET(CO(2))) and nasal/oral thermistor in 422 infants during overnight laboratory recordings to determine concordance between techniques, sources of disagreement, and capacity of RIP to detect obstructed breaths within an apnea. Among 233 episodes of apnea identified by at least one method as >/= 16 s, 120 were observed by the CHIME monitor, 219 by PET(CO(2)), and 163 by thermistor. The positive predictive value of the CHIME-identified apnea was 89.2% (95% CI 83, 95) and 73% (95% CI 65, 81) for PET(CO(2)) and thermistor, respectively. However, the sensitivity of the CHIME monitor in identifying events detected by the other methods was only approximately 50%. Among 87 apnea events identified by all three techniques, no two methods showed high agreement in measurement of apnea duration: RIP and PET(CO(2)) (ICC = 0.54), RIP and thermistor (ICC = 0.13), PET(CO(2)) and nasal thermistor (ICC = 0.41). Among the 179 breaths identified by RIP as obstructed, 79.9% were judged to be obstructed on the PET(CO(2)) and 80.4% were judged to be obstructed on the thermistor channel. Among 238 breaths identified on PET(CO(2)) as obstructed, 54.2% were determined to be obstructed by RIP. Among 204 breaths identified on thermistor as obstructed, 55. 4% were determined to be obstructed by RIP. Reasons for discrepancies in apnea detection among channels included body movement, partial airway obstruction, and obstructed breaths. Despite these limitations the CHIME monitor provides an opportunity to record physiological data previously unavailable in the home.

Apnea↗
PubMed1999

Microspheres based detoxification system: in vitro study and mathematical estimation of filter performance.

Because of the closed plasma (secondary) circuit in the Microspheres based Detoxification System (MDS), a convective blood purification system, the same amount of filtrated plasma is backfiltrated into the blood circuit. Therefore, there is no direct way to determine the ultrafiltrate production rate, which is an important factor of efficiency. The only possible way to estimate the filtration properties of the filter is to consider pressure values. In this study the pressure distribution in the filter was investigated in vitro. To explain the results and to calculate inaccessible parameters, a mathematical model was established which also considered the asymmetric behaviour of the filter membrane. The result was a linear pressure gradient, agreement with the measurements was reasonably good (calculated primary pressure loss differs <13% from measured value when using mean measured filter resistance as model parameter). Linear pressure distribution offers the possibility of easily calculating the filtration length, a parameter which can be used to estimate the filter condition. The comparison between calculated filtration and backfiltration rates offers an instrument of control for these values.

Adsorption↗
PubMed1997

Infant polysomnography: reliability. Collaborative Home Infant Monitoring Evaluation (CHIME) Steering Committee.

Infant polysomnography (IPSG) is an increasingly important procedure for studying infants with sleep and breathing disorders. Since analyses of these IPSG data are subjective, an equally important issue is the reliability or strength of agreement among scorers (especially among experienced clinicians) of sleep parameters (SP) and sleep states (SS). One basic issue of this problem was examined by proposing and testing the hypothesis that infant SP and SS ratings can be reliably scored at substantial levels of agreement, that is, kappa (kappa) > or = 0.61. In light of the importance of IPSG reliability in the collaborative home infant monitoring evaluation (CHIME) study, a reliability training and evaluation process was developed and implemented. The bases for training on SP and SS scoring were CHIME criteria that were modifications and supplements to Anders, Emde, and Parmelee (10). The kappa statistic was adopted as the method for evaluating reliability between and among scorers. Scorers were three experienced investigators and four trainees. Inter- and intrarater reliabilities for SP codes and SSs were calculated for 408 randomly selected 30-second epochs of nocturnal IPSG recorded at five CHIME clinical sites from healthy full term (n = 5), preterm (n = 4), apnea of infancy (n = 2), and siblings of the sudden infant death syndrome (SIDS) (n = 4) enrolled subjects. Infant PSG data set 1 was scored by both experienced investigators and trained scorers and was used to assess initial interrater reliability. Infant PSG data set 2 was scored twice by the trained scorers and was used to reassess inter-rater reliability and to assess intrarater reliability. The kappa s for SS ranged from 0.45 to 0.58 for data set 1 and represented a moderate level of agreement. Therefore, rater disagreements were reviewed, and the scoring criteria were modified to clarify ambiguities. The kappa s and confidence intervals (CIs) computed for data set 2 yielded substantial inter-rater and intrarater agreements for the four trained scorers; for SS, the kappa = 0.68 and for SP the kappa s ranged from 0.62 to 0.76. Acceptance of the hypothesis supports the conclusion that the IPSG is a reliable source of clinical and research data when supported by significant kappa s and CIs. Reliability can be maximized with strictly detailed scoring guidelines and training.

Humans↗
PubMed1995

SIDS prevention.

The mortality attributed to sudden infant death syndrome ahs decreased significantly in Northern Europe and Australia in conjunction with the majority of infants being placed to sleep on their back or side instead of on their stomach. Since the AAP recommendation in 1992 to place healthy infants on their back or side to sleep, the fraction of infants sleeping prone in the United States has decreased to approximately 43%. It is hoped that the national "Back to Sleep" education campaign will accelerate the acceptance of back or side sleeping for healthy infants so that only a small fraction of infants will be sleeping on their stomach within the next few years. Health-care providers should promote the recommendation in the newborn nursery and at well-baby visits. They should encourage dialogue with caregivers regarding this and other early infant care practices. It is still too soon to know how predominantly nonprone sleeping will affect the rate of SIDS in the United States. It is important that providers continue to stress access to prenatal and well-baby care, and cessation of smoking and substance abuse, as these risk factors may play a larger role in the high-risk communities in the United States. Pediatric medical personnel should advocate for proper death certification for infants and children, to include state legislation that supports autopsies for sudden unexpected deaths in children, and the establishment of state child fatality investigation and review teams. They also should participate in the training of death scene investigators or be part of the death scene investigative team.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1994

Proceedings of "Workshop on Guidelines for Scene Investigation of Sudden Unexplained Infant Deaths"--July 12-13, 1993.

The 1992 Senate Report #102-104 and House Report #102-121 recommended that the Interagency Panel on Sudden Infant Death Syndrome (SIDS) review and establish an updated standard death scene investigation protocol for scene investigation of unexplained infant deaths. As a result of the recommendation, the Centers for Disease Control and Prevention's (CDC) Division of Reproductive Health (DRH), and the National Institute for Child Health and Human Development (NICHD) organized a workshop entitled "Workshop on Guidelines for Scene Investigation of Sudden Unexplained Infant Deaths," which was held in Rockville, Maryland, on July 12-13, 1993. This article outlines the proceedings of the workshop. The goal of the workshop was to gather information and ideas that could be used to establish guidelines which could be useful in developing a model death scene investigation protocol. It was not a goal of this workshop to produce a specific protocol during the workshop. The workshop was successful in generating a variety of information and ideas concerning the desirable attributes of a protocol including essential items of data, identification of certain training needs, specification of procedures for data collection, reporting, and quality assurance, and proposed strategies for implementation. This information can now be considered by the HHS Interagency SIDS Panel to develop specific guidelines for developing a standard scene investigation protocol for sudden unexplained infant deaths.

Autopsy↗
PubMed1994

Infant sleep position and risk for sudden infant death syndrome: report of meeting held January 13 and 14, 1994, National Institutes of Health, Bethesda, MD.

OBJECTIVE: To evaluate the current knowledge on the relationship between infant sleep position and sudden infant death syndrome (SIDS), and to determine how the information can be used to guide further activities in the United States. METHODS: Data from international vital statistics, epidemiologic studies of SIDS risk factors, and studies of outcomes of public health interventions that advocated nonprone sleeping to reduce the risk for SIDS were discussed at a meeting held by the National Institute of Child Health and Human Development (NICHD) with cosponsorship from the National Institute on Deafness and Other Communication Disorders (NIDCD), and the National Center for Health Statistics (NCHS) on January 13, and 14, 1994. RESULTS: Trends in postneonatal mortality and SIDS rates from 1980 through 1992 were evaluated for Australia, Britain, New Zealand, the Netherlands, Norway, Sweden, and the United States. All of the countries that experienced a rapid decline in prone sleeping also had reductions of approximately 50% in their SIDS rates. Postneonatal mortality rates dropped as well, with the reduction in SIDS being the primary contributor to the reported declines. The major behavioral change in all targeted populations was in sleep position. No significant changes were observed in the proportion of parents who smoked cigarettes, or in breast-feeding. Preliminary data from population-based studies showed there were no reported adverse outcomes associated with a change to side or back sleep position, such as an increase in deaths due to aspiration or in apparent life-threatening events. CONCLUSION: The overwhelming opinion of the assembled experts was that the evidence justified greater effort to reach parents with the American Academy of Pediatrics' recommendation that healthy infants, when being put down to sleep, be positioned on their side or back.

Humans↗
PubMed1985

Cytoplasmic morphology weaver (wv) mouse cerebellar neurons at the culture substratum.

The purpose of this study was to determine the structural basis for the hypermotility and impaired growth cone elongation of the homozygous weaver (wv/wv) mouse cerebellar granule cell neurons in culture. Two-day cultures of dissociated week-old normal (+/+) and wv/wv cerebellum were processed for electron microscopy of intact cells and cytoskeleton. Serial sections parallel to and starting from the substrate were examined. Fine-caliber neurites of normal granule cells are packed with parallel arrays of microtubules at all levels. Microfilament-packed microspikes are present at substrate level emanating from a cortical microfilament lattice at the terminus of neurites of varying length. Homozygous weaver granule cells at substrate level have lateral cytoplasmic extensions along the neurite. Microtubules that curve throughout the neurite are separated by cytoplasm. The lateral extensions and growth cone cytoplasmic projections contain microfilaments and occasionally microtubules. Microfilament-packed microspikes are not observed. Immunofluorescent detection of actin confirms the ultrastructural picture. A hallmark of the wv/wv cytopathology is the presence of large numbers of coated vesicles throughout the neurite shaft at the cell-substratum interface. These are rare at similar locations in +/+ neurites. We hypothesize that reduced tension in the growth cone and neurite owing to the presence of lateral extensions and absence of stable microspikes are responsible for the impaired elongation and hypermotility of mutant neurons.

Actins↗
PubMed1985

Effect of the weaver (wv) mutation on cerebellar neuron differentiation. I. Qualitative observations of neuron behavior in culture.

A mutant gene dose-dependent inhibition of cerebellar granule cell neuron survival and neurite growth in dissociated cultures of cerebellum from 7-day-old heterozygous (+/wv) and homozygous (wv/wv) weaver mutant mice (M. Willinger, D. M. Margolis, and R. L. Sidman. (1981), J. Supramol. Struc. 17, 79-86) has previously been observed. In the present phase-contrast study time-lapse microcinematography was performed between 10 and 80 hr in culture to determine which properties of neurite growth and neuron migration are affected by weaver gene expression. Neurite growth in +/+ cultures is rapid and discontinuous. Neurites are thin and cylindrical. Membrane movement occurs only at the growth cone. Growth cone contact with cell aggregates or glial somas results in the cessation of cone advancement and the induction of translocation of the neuronal soma toward the astrocyte. In cultures of +/wv and wv/wv cerebellar cells, abnormal neurite growth is characterized by frequent neurite retractions and reinitiations. Neuronal somas and neurite shafts are motile during elongation. Homozygous neurites and cones are pleomorphic. Normal, +/wv, and wv/wv neurons undergo nuclear translocation. Like +/+ neurons, +/wv neurons migrate in response to growth cone-cell soma contact. In contrast, homozygous soma frequently reverse direction and migrate independently of cell contact. Granule cell death occurs with increasing frequency with increasing gene dosage. Neurons are unusually active prior to the rapid onset of cell death. In summary, the weaver mutation impairs granule cell differentiation by affecting neurite maintenance, membrane motility, and neuron morphology. The loss of viability appears to be independent of, or secondary to, these targets of gene action.

Animals↗
PubMed1985

Effect of the weaver (wv) mutation on cerebellar neuron differentiation. II. Quantitation of neuron behavior in culture.

Quantitative measurements of neuron behavior from time-lapse microcinematography of dissociated cultures of normal (+/+), heterozygous weaver (+/wv), and homozygous weaver (wv/wv) 7-day-old mouse cerebellum were performed to identify dose-dependent expressions of the mutant allele. Impaired neurite growth by granule cell neurons is a direct result of a dose-dependent increased frequency of neurite retraction and decreased rate of growth cone advancement. The number of retractions per neurite is 0.2, 1.0, and 2.0 for +/+, +/wv, and wv/wv neurites, respectively. Maximal rates of growth cone advancement are 1041, 443, and 250 micron/day for +/+, +/wv, and wv/wv granule cell neurites, respectively. Neurite initiation is actually increased in wv/wv cultures, though the neurites are not well sustained. The frequency of neurite initiation is 1.0, 1.7, and 2.2 for +/+, +/wv, and wv/wv neurons, respectively. Measurements of oscillations of somal position revealed that the cell center moves increasing distances over short times in proportion to the number of mutant genes. Nuclear translocation, the mode of somal migration in vivo and in vitro, occurs at the same frequency and rate in normal and mutant cultures. Weaver gene expression induces a cytopathology affecting various morphogenetic events rather than producing a block at a specific stage in granule cell differentiation. It is hypothesized that the dose-dependent impairments of cell motility reflect weaver gene action at the cell surface or cytoskeleton.

Animals↗
PubMed1983

Ganglioside localization on myelinated nerve fibres by cholera toxin binding.

GM1 ganglioside has been localized on the surfaces of myelinated, peripheral nerve fibres by using immunofluorescence to detect cholera toxin receptors. Unfixed, mouse sciatic nerves were teased into individual, intact fibres in order to expose their extracellular surfaces. Cholera toxin binding sites were abundant at all nodes of Ranvier; they were scarce on the internodal fibre surfaces. The nodal receptors were resistant to various degradative enzymes, including trypsin and proteinase K. Proteases did not unmask receptors on the internodal surfaces. Exogenous GM1 successfully competed for the toxin binding sites on the fibres. From this evidence and the specificity of cholera toxin binding, we conclude that GM1 ganglioside is abundantly present on the membrane surfaces of peripheral nodes of Ranvier and is not present on the internodal Schwann cell surfaces in an appreciable amount. The patterns of fluorescence within the node suggest that the axon and Schwann cell structures are sites where GM1 is localized. Treatment of the teased fibres with Vibrio cholerae neuraminidase, which is known to reduce polysialogangliosides to the monosialoganglioside GM1, induced cholera toxin binding on the internodal Schwann cell surfaces. The induced receptors, as well as their precursors, were resistant to trypsin and proteinase K. We conclude that the internodal Schwann cell surface is rich in an unidentified polysialoganglioside(s) that can be converted to GM1 by neuraminidase.

Animals↗
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.

Animals↗
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↗