Biomedical subjects
Publications and source records attributed to M Snyder.
The use of healthcare technology in homes is increasing. This article details an electronic home spirometry unit used by lung transplant patients. The unit can also be used with other populations including persons with asthma or cystic fibrosis, or persons awaiting transplants. Home health nurses are in a prime position to assist patients in using technology that provides direction for the treatment regimen.
Three human genes encoding proteins homologous to Drosophila Dishevelled protein were cloned and characterized. Amino acid similarity between the different Dishevelled proteins is concentrated in three highly conserved regions. Two of these regions do not exhibit significant sequence similarity with other known proteins; the third is similar to the discs-large homology region, which was first found in a Drosophila Discs-large tumor suppressor protein (also known as GLGF or PDZ domain). We produced antibodies against human Dishevelled-2 and demonstrated that it is a phosphoprotein and can be detected in all cell lines and human embryonic tissues examined. Indirect immunofluorescence indicates that it is found throughout the cytoplasm. Our results indicate that the human dishevelled genes constitute a multigene family and that Dishevelled proteins are highly conserved among metazoans.
Protein kinase C (PKC) signaling is highly conserved among eukaryotes and has been implicated in the regulation of cellular processes such as cell proliferation and growth. In the budding yeast, PKC1 functions to activate the SLT2(MPK1) mitogen-activated protein (MAP) kinase cascade, which is required for the maintenance of cell integrity during asymmetric cell growth. Genetic studies, coimmunoprecipitation experiments, and analysis of protein phosphorylation in vivo and in vitro indicate that the SBF transcription factor (composed of Swi4p and Swi6p), an important regulator of gene expression at the G1 to S phase cell cycle transition, is a target of the Slt2p(Mpk1p) MAP kinase. These studies provide evidence for a direct role of the PKC1 pathway in the regulation of the yeast cell cycle and cell growth and indicate that conserved signaling pathways can act to control key regulators of cell division.
Chitin is an essential structural component of the yeast cell wall whose deposition is regulated throughout the yeast life cycle. The temporal and spatial regulation of chitin synthesis was investigated during vegetative growth and mating of Saccharomyces cerevisiae by localization of the putative catalytic subunit of chitin synthase III, Chs3p, and its regulator, Chs5p. Immunolocalization of epitope-tagged Chs3p revealed a novel localization pattern that is cell cycle-dependent. Chs3p is polarized as a diffuse ring at the incipient bud site and at the neck between the mother and bud in small-budded cells; it is not found at the neck in large-budded cells containing a single nucleus. In large-budded cells undergoing cytokinesis, it reappears as a ring at the neck. In cells responding to mating pheromone, Chs3p is found throughout the projection. The appearance of Chs3p at cortical sites correlates with times that chitin synthesis is expected to occur. In addition to its localization at the incipient bud site and neck, Chs3p is also found in cytoplasmic patches in cells at different stages of the cell cycle. Epitope-tagged Chs5p also localizes to cytoplasmic patches; these patches contain Kex2p, a late Golgi-associated enzyme. Unlike Chs3p, Chs5p does not accumulate at the incipient bud site or neck. Nearly all Chs3p patches contain Chs5p, whereas some Chs5p patches lack detectable Chs3p. In the absence of Chs5p, Chs3p localizes in cytoplasmic patches, but it is no longer found at the neck or the incipient bud site, indicating that Chs5p is required for the polarization of Chs3p. Furthermore, Chs5p localization is not affected either by temperature shift or by the myo2-66 mutation, however, Chs3p polarization is affected by temperature shift and myo2-66. We suggest a model in which Chs3p polarization to cortical sites in yeast is dependent on both Chs5p and the actin cytoskeleton/Myo2p.
Analysis of the function of a particular gene product typically involves determining the expression profile of the gene, the subcellular location of the protein, and the phenotype of a null strain lacking the protein. Conditional alleles of the gene are often created as an additional tool. We have developed a multifunctional, transposon-based system that simultaneously generates constructs for all the above analyses and is suitable for mutagenesis of any given Saccharomyces cerevisiae gene. Depending on the transposon used, the yeast gene is fused to a coding region for beta-galactosidase or green fluorescent protein. Gene expression can therefore be monitored by chemical or fluorescence assays. The transposons create insertion mutations in the target gene, allowing phenotypic analysis. The transposon can be reduced by cre-lox site-specific recombination to a smaller element that leaves an epitope tag inserted in the encoded protein. In addition to its utility for a variety of immunodetection purposes, the epitope tag element also has the potential to create conditional alleles of the target gene. We demonstrate these features of the transposons by mutagenesis of the SPA2, ARP100, SER1, and BDF1 genes.
Electronic spirometry units were used to monitor lung transplantation recipients upon their return home. The data from 77 participants were used to develop methods to verify that the pulmonary function measurements, forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1), were reliable and valid. The standard deviation was calculated for the best daily effort on consecutive days of home spirometry. An acceptable upper limit for the standard deviation, as the measure of day-to-day reliability, was 0.20 for FVC and 0.15 for FEV1. Validity was determined by examining the mean difference (bias) between the spirometry done in the pulmonary function laboratory and the home monitoring results. The clinic values were slightly higher, with an average difference of 0.15 for FVC and 0.12 for FEV1. Therefore, the home spirometry measurements have a high degree of reliability and validity and can now be used for early detection of serious complications.
Because the reporting requirements imposed by the Residency Review Committee (RRC) for Obstetrics and Gynecology have become more extensive, we sought to develop a Microsoft Windows 3.1 (Microsoft Corp., Redmond, WA)-based computer program for maintaining an on-line record of resident surgical experience. Data input for our program occurs in two stages. All residents are responsible for maintaining separate obstetrics and gynecology-primary care statistical booklets. Each booklet consists of individual perforated data sheets. The front of the obstetrics data sheets is a replica of the bottom portion of RRC S Form Obstetrics. The reverse side is a replica of the top half of S Form Obstetrics, listing all "accountable" obstetric procedures, coded by level of operator responsibility. The front of the gynecology data sheet replicates the S Form Primary and Preventive Ambulatory Medicine. The reverse of this sheet is a replica of S Form Gynecology and lists all "accountable" gynecologic procedures, again coded by level of operator responsibility. Residents submit data sheets on a daily basis to the residency program coordinator, who then enters each patient encounter into a user-friendly data base program. Data entry screens are essentially identical to the individual encounter forms, and input requires fewer than 30 seconds per form. Once the individual patient's data is entered on the screen, the computer program automatically updates the resident's cumulative surgical experience and stratifies experience by year of training. At any time, program administrators have on-line access to a comprehensive record of an individual resident's or group of residents' clinical experience.
Rom2p is a GDP/GTP exchange factor for Rho1p and Rho2p GTPases; Rho proteins have been implicated in control of actin cytoskeletal rearrangements. ROM2 and RHO2 were identified in a screen for high-copy number suppressors of cik1 delta, a mutant defective in microtubule-based processes in Saccharomyces cerevisiae. A Rom2p::3XHA fusion protein localizes to sites of polarized cell growth, including incipient bud sites, tips of small buds, and tips of mating projections. Disruption of ROM2 results in temperature-sensitive growth defects at 11 degrees C and 37 degrees C. rom2 delta cells exhibit morphological defects. At permissive temperatures, rom2 delta cells often form elongated buds and fail to form normal mating projections after exposure to pheromone; at the restrictive temperature, small budded cells accumulate. High-copy number plasmids containing either ROM2 or RHO2 suppress the temperature-sensitive growth defects of cik1 delta and kar3 delta strains. KAR3 encodes a kinesin-related protein that interacts with Cik1p. Furthermore, rom2 delta strains exhibit increased sensitivity to the microtubule depolymerizing drug benomyl. These results suggest a role for Rom2p in both polarized morphogenesis and functions of the microtubule cytoskeleton.
The purpose of the study was to identify the parental concerns of Mexican American first-time mothers and fathers using an ethnographic approach. The study was conducted for 10 months in Hidalgo County, Texas. Twenty-six families were followed longitudinally during their first 6 months of parenting with an average of eight (SD = 1.8) home visits per family. Audio-taped conversations with participants were transcribed verbatim in their entirety in either Spanish or English. Spanish transcripts were translated and checked for accuracy by a local consultant. Salient parental concerns derived from content analysis were infant illness, providing for the material needs of the infant, threats infants face in the future, knowing how to rear an infant, and facing job loss. Public health nurses can collaborate with parents by working from expressed concerns to enhance family health and the health of the local community.
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DNA gyrase, the bacterial enzyme that supercoils DNA, is trapped on chromosomal DNA by the 4-quinolone compounds, as drug-gyrase complexes that contain DNA breaks. Examination of chromosomal DNA extracted from Escherichia coli indicated that bacteriostatic concentrations of oxolinic acid trap gyrase and block DNA synthesis without releasing broken DNA from gyrase-DNA complexes. Release, detected as free rotation of DNA in the presence of an intercalating dye, occurred only at high, bactericidal oxolinic acid concentrations. Release of DNA breaks and cell death were both blocked by chloramphenicol, an inhibitor of protein synthesis, suggesting that synthesis of additional protein activity is required to free the DNA ends. Ciprofloxacin, a more potent quinolone, released DNA breaks and killed cells even in the presence of chloramphenicol. It is proposed that this second, chloramphenicol-insensitive mode for release of DNA breaks and cell killing arises from dissociation of gyrase subunits. Ciprofloxacin also killed a gyrase (gyrA) mutant resistant to the prototype of quinolone, nalidixic acid, and created complexes on DNA detected by DNA fragmentation. This lethal effect of ciprofloxacin was eliminated by additional mutations mapping in parC, one of the two genes encoding topoisomerase IV. Thus, the fluoroquinolone compounds have two intracellular targets. In the absence of the gyrA mutation, the parC (CipR) allele did not by itself confer resistance to ciprofloxacin, indicating that gyrase is the major quinolone target in E. coli. These findings provide a molecular explanation for quinolone action in bacteria and a new way to study topoisomerase IV-chromosome interactions.
Spa2p and Cdc10p both participate in bud site selection and cell morphogenesis in yeast, and spa2delta cdc10-10 cells are inviable. To identify additional components important for these processes in yeast, a colony-sectoring assay was used to isolate high-copy suppressors of the spa2delda cdc10-10 lethality. One such gene, AXL2, has been characterized in detail. axl2 cells are defective in bud site selection in haploid cells and bud in a bipolar fashion. Genetic analysis indicates that AXL2 falls into the same epistasis group as BUD3. Axl2p is predicted to be a type I transmembrane protein. Tunicamycin treatment experiments, biochemical fractionation and extraction experiments, and proteinase K protection experiments collectively indicate that Axl2p is an integral membrane glycoprotein at the plasma membrane. Indirect immunofluorescence experiments using either Axl2p tagged with three copies of a hemagglutinin epitope or high-copy AXL2 and anti-Axl2p antibodies reveal a unique localization pattern for Axl2p. The protein is present as a patch at the incipient bud site and in emerging buds, and at the bud periphery in small-budded cells. In cells containing medium-sized or large buds, Axl2p is located as a ring at the neck. Thus, Axl2p is a novel membrane protein critical for selecting proper growth sites in yeast. We suggest that Axl2p acts as an anchor in the plasma membrane that helps direct new growth components and/or polarity establishment components to the cortical axial budding site.
The mammalian homeodomain proteins encoded by Hox genes play an important role in embryonic development by providing positional queues which define developmental identities along the anteroposterior axis of developing organisms. These proteins bind DNA specifically through their homeodomain to sequences containing ATTA cores, and thereby are thought to exert their effect regulating downstream genes. Little is known about the specificity of binding of homeodomain proteins to their sequences and the identity of their target genes. We have developed a transcriptional activation assay in yeast which employs a homeobox/VP16 fusion gene as a transcriptional activator and a target construct in which test fragments of DNA are inserted upstream to a reporter gene. Using this assay, we compared transcriptional activation by three chimeric proteins containing the homeodomains of the mouse homeobox genes, Hoxa-5, Hoxb-6, and Hoxc-8. When tested on previously defined target sequences, strong differential specificities of activation were observed. In an effort to identify enhancers that normally respond to homeodomain transcriptional activators, random fragments of mouse genomic DNA were cloned upstream of the reporter gene. Genomic DNA fragments with distinct activation profiles were obtained and were found to share matches beyond the ATTA core with previously described enhancers. These results demonstrate that the transcriptional activation system in yeast can be used as a convenient system to detect DNA motifs which bind homeodomain proteins, and subsequently, to identify authentic target genes responsive to Hox gene proteins.
In two experiments, we examined the hypothesis that subjective perceptions of message quality mediate the functional matching effect in persuasion. In Experiment 1, participants whose attitudes and behaviors serve primarily a value-expressive function (i.e., low self-monitors) or a social-adjustive function (i.e., high self-monitors) were exposed to persuasive messages that contained value-expressive, social-adjustive, or both types of arguments in favor of voting. Functionally-relevant messages (i.e., the social-adjustive message for high self-monitors and the value-expressive message for low self-monitors) produced enhanced perceptions of message quality and persuasiveness, more positive attitudes, and more message-related behavior than functionally nonrelevant messages. Functionally mixed messages were generally more effective than messages containing only functionally nonrelevant arguments, but less effective than messages containing only functionally relevant arguments. Path analyses indicated that the influence of functional relevance on attitudes and behavior was significantly mediated by subjective perceptions of the quality of the message. In Experiment 2, we exposed participants to a functionally relevant or nonrelevant voting appeal five days before a presidential election. Results replicated those of Experiment 1; functionally relevant messages produced more favorable attitudes, and this effect was mediated by enhanced perceptions of message quality. Finally, postmessage attitudes exerted a significant influence on whether participants voted in the election, and this effect was mediated by voting intentions. Discussion focuses on the subjective nature of message evaluation and on the cognitive processes underlying the functional matching effect in persuasion.
The purpose of this study was to develop a stressor inventory for use with a population of elderly Taiwanese people that allows the respondent to rate the degree of stressfulness of each stressor experienced, based on a transactional stress model. Thirty-three subjects identified stressors experienced from age 65 onwards. Seventy-three stressors were identified and listed in the instrument. Inter-rater agreement on the content was > or = 0.90. The psychometric properties of the instrument was established among 351 elderly Taiwanese subjects. In determining the stability of stressfulness, the generalizability coefficient for the relative decisions was 0.90 and generalizability coefficient for the absolute decision was 0.90. As to stability of stressor frequency, the generalizability coefficients for both the relative and absolute decisions was 0.72. Construct validity of the instrument was provided by a correlation of 0.59 with state-anxiety, of 0.56 with negative affect, and -0.28 with positive affect. Further refinement of the toll is in progress.
The budding yeast Saccharomyces cerevisiae responds to intracellular and extracellular cues to direct cell growth. Genetic analysis has revealed many components that participate in this process and has provided insight into the mechanisms by which these proteins function. Several of these components, such as the septins, pheromone receptors and GTPase proteins, have homologues in multicellular eukaryotes, suggesting that many aspects of polarized cell growth may be conserved throughout evolution. This review discusses our current understanding of the molecular mechanisms of growth-site selection during the different stages of the yeast life cycle.
This article reports findings from interviews with 20 parents about their experiences in obtaining services for their ADHD children in school systems. Grounded theory methods were used to analyze data at both individual and organizational levels. Parents saw school personnel as varying widely in their knowledge about ADHD and their acceptance of its associated problems. At the individual level, parents felt that they had to educate a succession of different school personnel each year. At the organizational level, they had to work actively to obtain continuity of services for their children from year to year and school to school, but for most parents, this outcome was desired more often than realized. On the whole, parents perceived schools as having failed to respond adequately to their children's educational needs.
Nurses are giving increasing attention to independent nursing interventions. However, numerous conceptualizations of interventions have evolved and are being used. The purpose of this essay is to examine some of the existing definitions and classification systems for interventions and to provide a rationale for a common universal language for nursing interventions. Definitions and approaches used in five intervention classification systems are examined in relation to inclusion of assessment and evaluation activities, autonomy, level of conceptualization, and inclusiveness of intervention labels. Lack of a common intervention language can deter international collaboration, development of a scientific basis for practice, and reimbursement for nursing services.