bluuebunny/crossref_metadata_2025_split huggingface dataset:
Misrepresenting random sampling? A systematic review of research papers in the Journal of Advanced Nursing
Authors: Williamson Graham R. 
Published: October 2003

Aim. This paper discusses the theoretical limitations of the use of random sampling and probability theory in the production of a significance level (or P‐value) in nursing research. Potential alternatives, in the form of randomization tests, are proposed.Background. Research papers in nursing, medicine and psychology frequently misrepresent their statistical findings, as the P‐values reported assume random sampling. In this systematic review of studies published between January 1995 and June 2002 in the Journal of Advanced Nursing, 89 (68%) studies broke this assumption because they used convenience samples or entire populations. As a result, some of the findings may be questionable.Discussion. The key ideas of random sampling and probability theory for statistical testing (for generating a P‐value) are outlined. The result of a systematic review of research papers published in the Journal of Advanced Nursing is then presented, showing how frequently random sampling appears to have been misrepresented. Useful alternative techniques that might overcome these limitations are then discussed.Review limitations. This review is limited in scope because it is applied to one journal, and so the findings cannot be generalized to other nursing journals or to nursing research in general. However, it is possible that other nursing journals are also publishing research articles based on the misrepresentation of random sampling. The review is also limited because in several of the articles the sampling method was not completely clearly stated, and in this circumstance a judgment has been made as to the sampling method employed, based on the indications given by author(s).Conclusion. Quantitative researchers in nursing should be very careful that the statistical techniques they use are appropriate for the design and sampling methods of their studies. If the techniques they employ are not appropriate, they run the risk of misinterpreting findings by using inappropriate, unrepresentative and biased samples.
Becoming a web‐based learner: registered nurses’ experiences
Authors: Atack Lynda 
Published: October 2003

Aims. The purpose of the study was to describe Registered Nurses’ experiences when taking a web‐based course from either the workplace or home, and the impact of their learning on clinical practice.Rationale. Little is known about the web‐based learners’ experience, particularly when courses are accessed from the nursing practice setting. Even less is known about whether nurses transfer their web‐based learning to clinical practice.Methods. A qualitative design employing focus group interviews was used. Participants included hospital and community nurses from three Canadian provinces and one territory. Data were collected at three points over a 6‐month period and analysed using a thematic analysis process. These findings emanate from a larger study using survey method and focus group interviews.Results. The focus group interviews captured the hurdles nurses faced during the first weeks when they struggled with technology, re‐framed their views of teaching and adjusted to web‐based learning from home and work. These first stressful weeks were followed by a period during which nurses developed relationships with the teacher and peers that enabled them to focus on learning and prevented attrition. Most nurses reported the web course was convenient and that they would be interested and comfortable using technology for learning and work purposes in the future. Six weeks after the course was completed, nurses articulated a number of ways the course had improved their practice.Conclusion. Initial weeks in a web‐based course can be very challenging for novice Internet users, however, most nurses who completed the course reported a positive learning experience. Nurses, employers and educators should evaluate computer skills, computer access and the learning environment when preparing for web‐based learning.
Critical thinking disposition of Hong Kong Chinese and Australian nursing students
Authors: Tiwari Agnes , Avery Alan , Lai Patrick 
Published: October 2003

Background. Critical thinking is frequently cited as a desirable professional attribute and a highly valued educational outcome. Despite the abundance of literature on the subject, validation of the critical thinking construct in different cultural populations is under‐researched.Aim. The purpose of this study was to compare the critical thinking dispositions of Hong Kong Chinese and Australian nursing students.Design. A cross‐sectional design was used with two groups of nursing students in two universities, one in Hong Kong and the other in Australia. Critical thinking disposition was measured using the California Critical Thinking Disposition Inventory (CCTDI).Results. Significant differences were detected in critical thinking disposition between the two groups of students (P < 0·05), with the Hong Kong Chinese students failing to show a positive disposition toward critical thinking on the CCTDI total mean score, while the Australian students showed a positive disposition. Similarities and differences were also noted between the groups in CCTDI subscale mean scores.Conclusion. The findings contribute to knowledge of critical thinking by demonstrating differences and similarities between Hong Kong Chinese and Australian nursing students. The study raises questions about the effects of institutional, educational, professional and cultural factors on the disposition to think critically.
Training needs of midwifery assistants
Authors: McKenna Hugh , Hasson Felicity , Smith Miriam 
Published: October 2003

Background. Increasingly in the United Kingdom (UK) assistants are being introduced as part of the midwifery workforce. However, there appears to be little standardization in the qualifications and training provided.Aim. The aim of this study was to investigate what an educational programme for midwifery assistants should contain.Research methods. A total of 100 qualified midwives and 58 midwifery students were asked to complete a mailed questionnaire and subsequently 20 of these respondents were interviewed.Results. Respondents identified three levels of competencies that midwifery assistants should possess. They also acknowledged that midwives required specific training in how best to supervise assistants. Respondents maintained that each assistant should have a clinically‐based midwifery mentor and that rotation around different clinical areas should be included as part of a training programme. Furthermore, it was stressed that because midwives initiate, teach and supervise assistants, they should have a key role in planning training programmes and in the teaching and assessment processes. Nonetheless, it was accepted that such a role could divert the midwife from valuable contact time with the mother and baby, the opposite of what the introduction of assistants was intended to do.Conclusions. Before working in clinical areas midwifery assistants need practice‐based training that focuses on skills development. Communications and interpersonal skills should be included in the training as should placement experience in a variety of clinical settings. Midwives have a role in providing this training, and in mentoring and supervising midwifery assistants, but it is accepted that this could add to their workloads. Developments of this kind need to be evaluated, especially in terms of the impact on direct care by midwives.
Review of research on the health of caregiving grandparents
Authors: Grinstead Linda Nicholson , Leder Sharon , Jensen Susan , Bond Linda 
Published: October 2003

Aim. To provide a critical review of research literature on the health of grandparents raising grandchildren, and identify directions for future research.Methods. Approaches used to access the research studies for this review included a comprehensive search using relevant electronic databases and a thorough examination of the references in each published study.Findings. All studies but one were published after 1990. Samples consisted primarily of African‐American and Caucasian grandmothers in the United States of America. Earlier studies tended to describe health and other related concepts while more recent studies began to examine relationships between concepts. Most of the studies had a cross‐sectional design and only one evaluated interventions. Inconsistencies in the results of these studies were prevalent.Conclusions. Evaluation studies, longitudinal designs, and more varied study samples including cross‐cultural comparisons are needed to advance knowledge about grandparent caregivers’ health.
Influence of number and position of flasks in the monomer release, Knoop hardness and porosity of a microwave‐cured acrylic resin
Authors: de Oliveira V. M. B. , Léon B. L. T. , Del Bel Cury A. A. , Consani S. 
Published: October 2003

summary  Simultaneous irradiation of multiple flasks may have deleterious effects on the polymerization of microwave cured‐acrylic resins. This study evaluated the effect of the number and position of flasks in the monomer release, Knoop hardness and porosity of a microwave‐cured acrylic resin. Samples were made of Acron MC® (AMC, GC Dent. Ind. Corp.) processed at 500 W. The following associations of the number and position of the flasks were tested: one simple flask centrally placed on the turning plate (I, control); two flasks, one in the centre (IIa) and the other peripherally placed in the plate (IIb); two flasks centrally, one above (IIIa) and the other below (IIIb). The processing time varied according to the number of flasks: 3 or 4·5 min for one or two flasks, respectively. For monomer release, each specimen (n = 12) was put in an assay glass tube containing 6 mL of deionized water that was changed daily. Monomer levels were obtained by spectrophotometry at 206 nm. For hardness test (n = 10), 12 indentations were made in the surface of each specimen. Immersing the polished specimens in permanent ink and counting the porous in a stereo light microscope verified the porosity. Monomer release was significant before 24 h: GI = 263·1(153·3)a, GIIa = 236·9(180·2)a, GIIb = 441·5(446·2)a, GIIIa = 1216·6(857·9)b. Tukey test showed no statistically significant differences among the groups for porosity and hardness. Monomer release was affected by the position of the flask (P < 0·05).
Increased high‐affinity phosphodiesterase PDE2 gene expression in germ tubes counteracts CAP1‐dependent synthesis of cyclic AMP, limits hypha production and promotes virulence of Candida albicans
Authors: Bahn Yong‐Sun , Staab Janet , Sundstrom Paula 
Published: October 2003

SummaryFrequent interconversion between yeasts, pseudohyphae and true hyphae is a hallmark of Candida albicans growth in mammalian tissues. The requirement for transient CAP1‐dependent pulses of cAMP for generating true hyphae, Hwp1 and virulence raises questions about the role of yeast and pseudohyphal forms in the pathogenesis of candidiasis. In this study, hyperfilamentous mutants, limited in their capacity to produce buds, were generated by disrupting the high‐affinity phosphodiesterase gene PDE2. Degradation of cAMP by the PDE2 gene product was confirmed by higher basal cAMP levels in the pde2/pde2 mutant and by accumulation of cAMP to levels permitting germ tube formation upon disrupting PDE2 in the cap1/cap1 mutant. Similar phenotypes of the C. albicans and Saccharomyces cerevisiae pde2/pde2 mutants were found, including sensitivity to nutritional starvation and exogenous cAMP and defective entry into stationary phase. Importantly, the hyperfilamentous mutants were as avirulent as hypofilamentous mutants in a systemic model of candidiasis. Growth in a multiplicity of forms appears to be a virulence attribute that is controlled by tight coupling of cAMP synthesis and degradation. Delayed increases in PDE2 mRNA in cAMP‐deficient cap1/cap1 mutants during germ tube‐inducing conditions suggested a mechanism of control involving cAMP‐dependent induction of PDE2 mRNA.
Recipient‐induced transfer of the symbiotic plasmid pRL1JI in Rhizobium leguminosarum bv. viciae is regulated by a quorum‐sensing relay
Authors: Danino Vittoria E. , Wilkinson Adam , Edwards Anne , Downie J. Allan 
Published: October 2003

SummaryAnalysis of the regulation of plasmid transfer genes on the symbiotic plasmid pRL1JI in Rhizobium leguminosarum bv. viciae has revealed a novel regulatory relay that is specifically poised to detect an N‐acyl‐homoserine lactone (AHL) made by different cells (potential recipients of pRL1JI). Adjacent to the traI‐trbBCDEJKLFGHI plasmid transfer operon on pRL1JI are two regulatory genes, bisR and traR, which encode LuxR‐type quorum‐sensing regulators required for conjugation. Potential recipients of pRL1JI induce the traI‐trb operon and plasmid transfer via a quorum‐sensing relay involving BisR, TraR and the traI‐trb operon in donor cells. BisR induces expression of traR in response to N‐(3‐hydroxy‐7‐cis‐tetradecenoyl)‐l‐homoserine lactone (3‐OH‐C14:1‐HSL), which is produced by CinI in potential recipient strains. In donor strains (carrying pRL1JI), BisR represses the expression of the chromosomal gene cinI; this repression results in a very low level of formation of 3‐OH‐C14:1‐HSL and hence relatively low levels of expression of traR and the traI‐trb operon in strains carrying pRL1JI. However, if 3‐OH‐C14:1‐HSL from potential recipients is present, then traR and plasmid transfer are induced. The induction of traR occurs at very low concentrations of 3‐OH‐C14:1‐HSL (around 1 nm). TraR then induces the traI‐trb operon in a quorum‐sensing dependent manner in re‐sponse to the TraI‐made AHLs, N‐(3‐oxo‐octanoyl)‐l‐homoserine lactone and N‐(octanoyl)‐l‐homoserine lactone. The resulting autoinduction results in high levels of expression of the traI‐trb operon. Premature expression of the traI‐trb operon is reduced by TraM, which probably titres out TraR preventing expression of traI when there are low levels of traR expression. Expression of traR in stationary phase cells is limited by feedback inhibition mediated by TraI‐made AHLs.
Structural aspects of DNA repair: the role of restricted diffusion
Authors: Minsky Abraham 
Published: October 2003

SummaryDNA repair and protection processes impose arduous demands upon cellular systems. The high‐fidelity recombinational repair pathway entails a rapid genome‐wide search for sequence homology. The efficiency of this transaction is intriguing in light of the uniquely adverse diffusion traits of the involved species. DNA protection in cells exposed to continuous stress or prolonged starvation is equally enigmatic, because the ability of such cells to deploy energy‐dependent enzymatic repair processes is hampered as a result of progressive perturbation of the intracellular energy balance. DNA repair in radio‐resistant bacteria, which involves accurate chromosome reconstruction from multiple fragments, is similarly associated with apparently insurmountable logistical obstacles. The studies reviewed here imply that the mechanisms deployed to overcome these intrinsic hurdles have a basic common denominator. In all these cases, condensed and ordered chromatin assemblies are formed, within which molecular diffusion is restricted and confined. Restricted diffusion thus appears as a general strategy that is exploited by nature to facilitate homologous search, to promote energy‐independent DNA protection through physical DNA sequestration and attenuated accessibility to damaging agents, and to enable error‐free repair of multiple double‐strand DNA breaks.
Host collagen signal induces antigen I/II adhesin and invasin gene expression in oral Streptococcus gordonii
Authors: Heddle Catherine , Nobbs Angela H. , Jakubovics Nicholas S. , Gal Micaela , Mansell Jason P. , Dymock David , Jenkinson Howard F. 
Published: October 2003

SummaryMicrobial interactions with host molecules, and programmed responses to host environmental stimuli, are critical for colonization and initiation of pathogenesis. Bacteria of the genus Streptococcus are primary colonizers of the human mouth. They express multiple cell‐surface adhesins that bind salivary components and other oral bacteria and enable the development of polymicrobial biofilms associated with tooth decay and periodontal disease. However, the mechanisms by which streptococci invade dentine to infect the tooth pulp and periapical tissues are poorly understood. Here we show that production of the antigen I/II (AgI/II) family polypeptide adhesin and invasin SspA in Streptococcus gordonii is specifically upregulated in response to a collagen type I signal, minimally the tri‐peptide Gly‐Pro‐Xaa (where Xaa is hydroxyproline or alanine). Increased AgI/II polypeptide expression promotes bacterial adhesion and extended growth of streptococcal cell chains along collagen type I fibrils that are characteristically found within dentinal tubules. These observations define a new model of host matrix signal‐induced tissue penetration by bacteria and open the way for novel therapy opportunities for oral invasive diseases.
Disruption of mptpB impairs the ability of Mycobacterium tuberculosis to survive in guinea pigs
Authors: Singh Ramandeep , Rao Vivek , Shakila H. , Gupta Radhika , Khera Aparna , Dhar Neeraj , Singh Amit , Koul Anil , Singh Yogendra , Naseema M. , Narayanan P. R. , Paramasivan C. N. , Ramanathan V. D. , Tyagi Anil K. 
Published: October 2003

SummaryProtein tyrosine kinases and tyrosine phosphatases from several bacterial pathogens have been shown to act as virulence factors by modulating the phosphorylation and dephosphorylation of host proteins. The identification and characterization of two tyrosine phosphatases namely MptpA and MptpB from Mycobacterium tuberculosis has been reported earlier. MptpB is secreted by M. tuberculosis into extracellular mileu and exhibits a pH optimum of 5.6, similar to the pH of the lysosomal compartment of the cell. To determine the role of MptpB in the pathogenesis of M. tuberculosis, we constructed a mptpB mutant strain by homologous recombination and compared the ability of parent and the mutant strain to survive intracellularly. We show that disruption of the mptpB gene impairs the ability of the mutant strain to survive in activated macrophages and guinea pigs but not in resting macrophages suggesting the importance of its role in the host–pathogen interaction. Infection of guinea pigs with the mutant strain resulted in a 70‐fold reduction in the bacillary load of spleens in infected animals as compared with the bacillary load in animals infected with the parental strain. Upon reintroduction of the mptpB gene into the mutant strain, the complemented strain was able to establish infection and survive in guinea pigs at rates comparable to the parental strain. These observations demonstrate a   role   of MptpB in the pathogenesis   of M. tuberculosis.
ComX is a unique link between multiple quorum sensing outputs and competence in Streptococcus pneumoniae
Authors: Luo Ping , Li Haiying , Morrison Donald A. 
Published: October 2003

SummaryNatural competence for genetic transformation in Streptococcus pneumoniae is achieved directly by specific proteins that are involved in DNA uptake and chromosomal recombination, and is regulated indirectly by a quorum‐sensing system encoded by two loci, comAB and comCDE. The alternative sigma factor, ComX, is thought to be the unique link between quorum sensing and competence‐specific genes. To test this hypothesis, we replaced the quorum‐sensing inducible promoter (PQ) of the comX gene with either a constitutive promoter (PC) or a raffinose‐inducible promoter (PR), so that comX transcription would be independent of quorum sensing. Surprisingly, both competence and expression of late genes, such as ssbB, cglA or celB, were found to depend on CSP in these mutants. An unknown, CSP‐dependent regulator was needed when comX was expressed from these ectopic promoters, and it appears to act post‐transcriptionally. However, when a multicopy nisin‐inducible ComX‐overexpressing plasmid was introduced, pneumococcal cells developed competence in the presence of nisin even despite deletion of comE. At 1% of the normal protein peak level, ComX protein stimulated competence without the participation of the pheromone response circuit. Thus, ComX is a unique link to competence‐specific genes, but depends on multiple outputs of quorum sensing for maximal expression.
Cell cycle‐ and age‐dependent activation of Sod1p drives the formation of stress resistant cell subpopulations within clonal yeast cultures
Authors: Sumner Edward R. , Avery Angela M. , Houghton John E. , Robins R. Adrian , Avery Simon V. 
Published: October 2003

SummaryPhenotypic heterogeneity describes non‐genetic variation that exists between individual cells within isogenic populations. The basis for such heterogeneity is not well understood, but it is evident in a wide range of cellular functions and phenotypes and may be fundamental to the fitness of microorganisms. Here we use a suite of novel assays applied to yeast, to provide an explanation for the classic example of heterogeneous resistance to stress (copper). Cell cycle stage and replicative cell age, but not mitochondrial content, were found to be principal parameters underpinning differential Cu resistance: cell cycle‐synchronized cells had relatively uniform Cu resistances, and replicative cell‐age profiles differed markedly in sorted Cu‐resistant and Cu‐sensitive subpopulations. From a range of potential Cu‐sensitive mutants, cup1Δ cells lacking Cu‐metallothionein, and particularly sod1Δ cells lacking Cu, Zn‐superoxide dismutase, exhibited diminished heterogeneity. Furthermore, age‐dependent Cu resistance was largely abolished in cup1Δ and sod1Δ cells, whereas cell cycle‐dependent Cu resistance was suppressed in sod1Δ cells. Sod1p activity oscillated ∼fivefold during the cell cycle, with peak activity coinciding with peak Cu‐resistance. Thus, phenotypic heterogeneity in copper resistance is not stochastic but is driven by the progression of individual cells through the cell cycle and ageing, and is primarily dependent on only Sod1p, out of several gene products that can influence the averaged phenotype. We propose that such heterogeneity provides an important insurance mechanism for organisms; creating subpopulations that are pre‐equipped for varied activities as needs may arise (e.g. when faced with stress), but without the permanent metabolic costs of constitutive expression.
Targeting of two signal transduction pathways to different regions of the bacterial cell
Authors: Wadhams G. H. , Warren A. V. , Martin A. C. , Armitage J. P. 
Published: October 2003

SummaryComponents of bacterial chemosensory pathways which sense via transmembrane receptors have been shown to localize to the cell poles. Many species, however, have operons encoding multiple putative chemosensory pathways, some including putative cytoplasmic receptors. In‐genome fusions to single or multiple genes encoding components of two chemosensory pathways in Rhodobacter sphaeroides, cheOp2 and cheOp3, revealed that while sensory transducing proteins associated with transmembrane receptors and encoded on cheOp2 were targeted to the cell poles, the proteins associated with putative cytoplasmic receptors and encoded on cheOp3 were all targeted to a cytoplasmic cluster. No proteins were localized to both sites. These data show that bacteria target components of related pathways to different sites in the cell, presumably preventing direct cross‐talk between the different pathways, but allowing a balanced response between extracellular and cytoplasmic signals. It also indicates that there is intracellular organization in bacterial cells, with specific proteins targeted and localized to cytoplasmic regions.