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David W. Johnson

Bio: David W. Johnson is an academic researcher from University of Queensland. The author has contributed to research in topics: Peritoneal dialysis & Kidney disease. The author has an hindex of 160, co-authored 2714 publications receiving 140778 citations. Previous affiliations of David W. Johnson include Minnesota Department of Transportation & Open University.


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Journal ArticleDOI
TL;DR: The results support the hypothesis that ECM and AM plants partition soil P sources, which may play an ecologically important role in promoting species coexistence in tropical and subtropical forests.
Abstract: Partitioning of soil phosphorus (P) pools has been proposed as a key mechanism maintaining plant diversity, but experimental support is lacking. Here, we provided different chemical forms of P to 15 tree species with contrasting root symbiotic relationships to investigate plant P acquisition in both tropical and subtropical forests. Both ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) trees responded positively to addition of inorganic P, but strikingly, ECM trees acquired more P from a complex organic form (phytic acid). Most ECM tree species and all AM tree species also showed some capacity to take up simple organic P (monophosphate). Mycorrhizal colonisation was negatively correlated with soil extractable P concentration, suggesting that mycorrhizal fungi may regulate organic P acquisition among tree species. Our results support the hypothesis that ECM and AM plants partition soil P sources, which may play an ecologically important role in promoting species coexistence in tropical and subtropical forests.

77 citations

Journal ArticleDOI
TL;DR: The spectrum and degree of severity of neurological abnormalities in survivors of NAHI is extremely variable, with the majority of these children being moderate or severely abnormal and requiring the support of a multi-disciplinary team in the community.
Abstract: Purpose: The literature regarding the outcome of non-accidental head injury (NAHI) is scarce and lacks specific detail even though it is generally considered to be poor The purpose of this study is to review the literature to date and report the neurological outcome of these children in detailMethods: A cross-sectional and prospective study of children admitted to hospital with NAHI in ScotlandResults: Twenty-five children were enrolled and 68% of children were neurologically abnormal at an average follow-up of 59 months A wide range of abnormalities and outcomes was seen Speech and language difficulties were present in 64% including autistic spectrum disorder Cranial nerve abnormalities were present in 20% Visual deficits and epilepsy compounded learning difficulties in 25% of survivors Consent for follow-up was more likely to be obtained where the perpetrator was knownConclusions: The spectrum and degree of severity of neurological abnormalities in survivors of NAHI is extremely variable, with

77 citations

Journal ArticleDOI
TL;DR: IP administration of antibiotics was superior to IV administration for treating PD-associated peritonitis and glycopeptide regimens appear optimal for complete cure ofperitonitis, although evidence for this finding was assessed as low quality.
Abstract: Background Peritonitis is a common complication of peritoneal dialysis (PD) that is associated with significant morbidity including death, hospitalisation, and need to change from PD to haemodialysis. Treatment is aimed to reduce morbidity and recurrence. This is an update of a review first published in 2008. Objectives To evaluate the benefits and harms of treatments for PD-associated peritonitis. Search methods For this review update we searched the Cochrane Renal Group's Specialised Register to March 2014 through contact with the Trials Search Co-ordinator using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE and EMBASE, and handsearching conference proceedings. Selection criteria We included randomised controlled trials (RCTs) and quasi-RCTs assessing the treatment of peritonitis in PD patients (adults and children). We included any study that evaluated: administration of an antibiotic by different routes (e.g. oral, intraperitoneal (IP), intravenous (IV)); dose of an antibiotic agent; different schedules of administration of antimicrobial agents; comparisons of different regimens of antimicrobial agents; any other intervention including fibrinolytic agents, peritoneal lavage and early catheter removal. Data collection and analysis Multiple authors independently extracted data on study risk of bias and outcomes. Statistical analyses were performed using the random effects model. We expressed summarised treatment estimates as a risk ratio (RR) with 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) with 95% CI for continuous outcomes. Main results We identified 42 eligible studies in 2433 participants: antimicrobial agents (36 studies); urokinase (4 studies), peritoneal lavage (1 study), and IP immunoglobulin (1 study). We did not identify any optimal antibiotic agent or combination of agents. IP glycopeptides (vancomycin or teicoplanin) had uncertain effects on primary treatment response, relapse rates, and need for catheter removal compared to first generation cephalosporins, although glycopeptide regimens were more likely to achieve a complete cure (3 studies, 370 episodes: RR 1.66, 95% CI 1.01 to 2.72). For relapsing or persistent peritonitis, simultaneous catheter removal and replacement was better than urokinase at reducing treatment failure rates (RR 2.35, 95% CI 1.13 to 4.91) although evidence was limited to a single small study. Continuous and intermittent IP antibiotic dosing schedules had similar treatment failure and relapse rates. IP antibiotics were superior to IV antibiotics in reducing treatment failure in one small study (RR 3.52, 95% CI 1.26 to 9.81). Longer duration treatment (21 days of IV vancomycin and IP gentamicin) had uncertain effects on risk of treatment relapse compared with 10 days treatment (1 study, 49 patients: RR 1.56, 95% CI 0.60 to 3.95) although may have increased ototoxicity. In general, review conclusions were based on a small number of studies with few events in which risk of bias was generally high; interventions were heterogeneous, and outcome definitions were often inconsistent. There were no RCTs evaluating optimal timing of catheter removal and data for automated PD were absent. Authors' conclusions Many of the studies evaluating treatment of PD-related peritonitis are small, out-dated, of poor quality, and had inconsistent definitions and dosing regimens. IP administration of antibiotics was superior to IV administration for treating PD-associated peritonitis and glycopeptides appear optimal for complete cure of peritonitis, although evidence for this finding was assessed as low quality. PD catheter removal may be the best treatment for relapsing or persistent peritonitis. Evidence was insufficient to identify the optimal agent, route or duration of antibiotics to treat peritonitis. No specific antibiotic appears to have superior efficacy for preventing treatment failure or relapse of peritonitis, but evidence is limited to few trials. The role of routine peritoneal lavage or urokinase is uncertain.

76 citations

Journal ArticleDOI
TL;DR: This paper reviewed studies of conflict for their treatment of communication, and the implications of these studies for communication theory are explicated in Section 3.1.1] and Section 2.2.
Abstract: Studies of conflict are critically reviewed for their treatment of communication. The implications of these studies for communication theory are explicated.

76 citations

Journal ArticleDOI
TL;DR: This study provides comprehensive data on trends of pediatric mental health presentation, and highlights the costs and return presentations in this population.
Abstract: OBJECTIVE: We sought to determine and compare rates of pediatric mental health presentations and associated costs in emergency departments (EDs) in Alberta. METHODS: We examined 16 154 presentations by 12 589 patients (patient age < or = 17 yr) between April 2002 and March 2006 using the Ambulatory Care Classification System, a province-wide database for Alberta. The following variables of interest were extracted: patient demographics, discharge diagnoses, triage level, disposition, recorded costs for ED care, and institutional classification and location (i.e., rural v. urban, pediatric v. general EDs). RESULTS: A 15% increase in pediatric mental health presentations was observed during the study period. Youth aged 13-17 years consistently represented the most common age group for first presentation to the ED (83.3%). Of the 16 154 recorded presentations, 21.4% were related to mood disorders and 32.5% to anxiety disorders. Presentations for substance misuse or abuse were the most prevalent reasons for a mental health-related visit (41.3%). Multiple visits accounted for more than one-third of all presentations. Presentations for mood disorders were more common in patients with multiple compared with single visits (29.3% v. 16.9%), and substance abuse or misuse presentations were more common in patients with single compared with multiple visits (47.4% v. 30.5%). The total direct ED costs for mental health presentations during the study period was Can$3.5 million. CONCLUSION: This study provides comprehensive data on trends of pediatric mental health presentation, and highlights the costs and return presentations in this population. Psychiatric and medical care provided in the ED for pediatric mental health emergencies should be evaluated to determine quality of care and its relationship with return visits and costs.

76 citations


Cited by
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Journal ArticleDOI
Eric S. Lander1, Lauren Linton1, Bruce W. Birren1, Chad Nusbaum1  +245 moreInstitutions (29)
15 Feb 2001-Nature
TL;DR: The results of an international collaboration to produce and make freely available a draft sequence of the human genome are reported and an initial analysis is presented, describing some of the insights that can be gleaned from the sequence.
Abstract: The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

22,269 citations

28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Book ChapterDOI
09 Jan 2004
TL;DR: A theory of intergroup conflict and some preliminary data relating to the theory is presented in this article. But the analysis is limited to the case where the salient dimensions of the intergroup differentiation are those involving scarce resources.
Abstract: This chapter presents an outline of a theory of intergroup conflict and some preliminary data relating to the theory. Much of the work on the social psychology of intergroup relations has focused on patterns of individual prejudices and discrimination and on the motivational sequences of interpersonal interaction. The intensity of explicit intergroup conflicts of interests is closely related in human cultures to the degree of opprobrium attached to the notion of "renegade" or "traitor." The basic and highly reliable finding is that the trivial, ad hoc intergroup categorization leads to in-group favoritism and discrimination against the out-group. Many orthodox definitions of "social groups" are unduly restrictive when applied to the context of intergroup relations. The equation of social competition and intergroup conflict rests on the assumptions concerning an "ideal type" of social stratification in which the salient dimensions of intergroup differentiation are those involving scarce resources.

14,812 citations

Journal ArticleDOI
TL;DR: In this paper, Imagined communities: Reflections on the origin and spread of nationalism are discussed. And the history of European ideas: Vol. 21, No. 5, pp. 721-722.

13,842 citations

Journal ArticleDOI
TL;DR: Reading a book as this basics of qualitative research grounded theory procedures and techniques and other references can enrich your life quality.

13,415 citations