Karyotypic analysis of adult pluripotent stem cells.

Three categories of precursor cells have been identified in postnatal mammals: tissue-committed progenitor cells, germ layer lineage-committed stem cells and lineage-uncommitted pluripotent stem cells. Progenitor cells are the immediate precursors of differentiated tissues. Germ layer lineage stem cells can be induced to form multiple cell types belonging to their respective ectodermal, mesodermal, and endodermal embryological lineages. Pluripotent stem cells will form somatic cell types from all three primary germ layer lineages. Progenitor cells demonstrate a finite life span before replicative senescence and cell death occur. Both germ layer lineage stem cells and pluripotent stem cells are telomerase positive and display extensive capabilities for self-renewal. Stem cells which undergo such extensive replication have the potential for undergoing mutations that may subsequently alter cellular functions. Gross mutations in the genome may be visualized as chromosomal aneuploidy and/or chromosomes that appear aberrant. This study was designed to determine whether any gross genomic mutations occurred within the adult pluripotent stem cells. Karyotypic analysis was performed using pluripotent stem cells purified from adult male rats using established procedures. Giemsa Banding was used in conjunction with light microscopy to visualize metaphase chromosome spreads. To date over 800 metaphase spreads have been analyzed. We found that the metaphase spreads averaged 42 chromosomes and concluded that these pluripotent stem cells isolated from adult rats have a normal karyotype.

Assessing nurse practitioner students using a modified objective structured clinical examination (OSCE).

Limitations of applying the traditional final medical examination for the assessment of clinical competence of nurse practitioners are a matter of concern. This paper discusses a modified Objective Structured Clinical Examination (OSCE) to assess physical examination skills of student nurse practitioners at Bournemouth University. This assessment was developed to standardize the evaluation of examining skills by using healthy volunteers from the student body as patients. This modified OSCE can be used as an assessment tool for formative and summative assessment, as a resource for learning, as a basis for abbreviated versions of physical examination assessments and to identify gaps and weaknesses in clinical skills. The emphasis, therefore, is not only on the product but also the process. The Bournemouth experience may be of interest to other organizations that are developing OSCEs for formative and summative purposes in nurse practitioner education.

Quantitative measurement of long range nuclear Overhauser enhancement.

Measurement of nuclear Overhauser enhancement is one of the mainstays of structural studies of molecules in solution. Measurements, particularly over long distances, are often compromised by spin diffusion. A robust and accurate method for measuring nuclear Overhauser enhancements that are largely free of spin diffusion effects is presented. The effects of using imperfect radiofrequency pulses are considered and experimental data are presented for Amphotericin B.

Preliminary results of the Annual Survey of Deaf and Hard of Hearing Children and Youth in Puerto Rico: the first wave.

Preliminary findings are provided from the data collected in Puerto Rico through the Annual Survey of Deaf and Hard of Hearing Children and Youth during the 1997-1998 school year. The study was conducted as a part of an initiative to increase participation in the Annual Survey among the deaf and hard of hearing school-age population in Puerto Rico. Demographic, instructional, etiological, audiological, and communication data on 336 deaf and hard of hearing school age children were collected and summarized. The findings suggest the existence of a heterogeneous deaf community rather than the traditionally conceived homogeneous community. The discussion emphasizes the description of those attributes that suggest heterogeneity and the urgent need to continue to collect the kind of data gathered in the survey. The authors urge that Puerto Rican educators and researchers be stimulated to address the educational and health-related needs of Puerto Rico's deaf and hard of hearing school-age population.

Demographic and audiological profiles of deaf children in Texas with cochlear implants.

This paper reports the findings of a study that examined the demographic, educational, and audiological characteristics of a sample of children in Texas who had received cochlear implants. Children who had received implants and children who had not were compared. Differences between the two groups are discussed in the context of the criteria that have been published in the literature for selecting implant candidates. Results indicate that although the published selection criteria were predictive of the characteristics of the implanted sample, there was a degree of flexibility in applying the criteria to choose implant recipients. Audiological comparisons revealed that cochlear implant recipients experience greater reductions in average hearing thresholds than do users of conventional aids, although these findings should be viewed as preliminary.

Genetic epidemiological studies of early-onset deafness in the U.S. school-age population.

Profound, early-onset deafness is present in 4-11 per 10,000 children, and is attributable to genetic causes in at least 50% of cases. Family history questionnaires were sent to 26,152 families of children with profound, early-onset deafness not known to be related to an environmental cause. The probands were ascertained through the 1988-89 Gallaudet University Annual Survey of Hearing Impaired Children and Youth. The analysis is based on the responses that were received from 8,756 families. Classical segregation analysis was used to analyze the family data, and to estimate the proportions of sporadic, recessive and dominant causes of deafness in the families. These data were consistent with 37.2% of the cases due to sporadic causes, and 62.8% due to genetic causes (47.1% recessive, and 15.7% dominant). An earlier study using the 1969-70 Annual Survey found 49.3% sporadic cases and 50.6% genetic, demonstrating that the proportion of sporadic cases of early-onset deafness has significantly decreased since 1970.

An acyl-carrier-protein-thioesterase domain from the 6-deoxyerythronolide B synthase of Saccharopolyspora erythraea. High-level production, purification and characterisation in Escherichia coli.

The C-terminal region of a multifunctional polypeptide from the 6-deoxyerythronolide B synthase of Saccharopolyspora erythraea is predicted to contain an acyl carrier protein and a thioesterase or acyltransferase activity [Cortes, J., Haydock, S. F., Roberts, G. A., Bevitt, D. J. & Leadlay, P. F. (1990) Nature 348, 176-178]. Site-directed mutagenesis by means of the polymerase chain reaction was used to construct an efficient pT7-based expression plasmid for this domain. The recently developed technique of electrospray mass spectrometry was used to demonstrate that the purified protein had not been post-translationally modified by attachment of a 4'-phosphopantetheine group. However, treatment with the serine proteinase inhibitor phenylmethylsulphonyl fluoride led to highly selective labelling of the predicted active site of the thioesterase or acyltransferase.

Coming clean: the symbolic use of clinical hygiene in a hospital sterilising unit.

The hospital Theatre Sterile Supplies Unit cleans and provides sterile instruments for use in operating theatres. The strict standards of cleanliness, based on scientific notions of clinical hygiene, are maintained at the everyday level by people such as ancillary workers, nurses and doctors organising their activities, movements and understandings according to known rules. Since clinical hygiene is related to advanced microbiological discoveries, an instrument cannot be judged sterile by the naked eye. The judgement is made on the basis of what is believed to be happening to the instrument (e.g. processes it goes through; places it has been). The paper, based on an empirical study, notes the conceptual relationship between primitive and western notions of hygiene, and examines the ways that rules are used in the everyday accomplishment of instrument sterilisation.

Production of new polyene antibiotics by Streptomyces cellulosae after addition of ethyl (Z)-16-phenylhexadec-9-enoate.

Ethyl (Z)-16-phenylhexadec-9-enoate (3), an analog of ethyl oleate (2), was synthesized and added to cultures of Streptomyces cellulosae ATCC 12625 which normally produce fungichromin (1) as the principal polyene antibiotic. These cultures showed drastic reduction of fungichromin biosynthesis but afforded four new polyene antibiotics with a truncated four carbon side chain which are designated as isochainin (11) (an isomer of chainin (10], 14-hydroxyisochainin (12), 1'-hydroxyisochainin (13), and 1',14-dihydroxyisochainin (14). The close correspondence of 13C NMR chemical shifts between these compounds and fungichromin suggests that the stereochemistry at every site is exactly analogous.

Hearing-impaired children under age 6: a demographic analysis.

This paper presents information about hearing-impaired children under the age of 6 who are receiving special educational services in the United States and have been reported to the Annual Survey of Hearing-Impaired Children and Youth conducted by Gallaudet University's Center for Assessment and Demographic Studies. Results indicate an increase in the number of hearing-impaired children under age 6 reported to the survey over the last 10 years, especially children from minority backgrounds. The second section of the analysis focuses on students from schools participating in a model state project that encourages early identification and provision of services to hearing-impaired students and their families. The data pertain only to those children who are receiving services through established programs reporting to the Annual Survey; thus, inferences about the overall prevalence of hearing impairment among this age group should not be drawn.