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.

Extended high frequency hearing sensitivity: a normative threshold study in musicians

Abstract: Sixty members of the Minnesota Orchestra (aged 24 to 64 years) and 30 nonmusicians (aged 20 to 69 years) were evaluated for hearing sensitivity within the conventional audiometric range (0.25 to 8 kHz) and within the extended high frequency audiometric range (9 to 20 kHz). Threshold data were evaluated by age, sex, and musician-nonmusician categories for the respective frequencies, and data were compared to other studies. Musician hearing appeared no poorer than nonmusician hearing, suggesting no major hearing loss from musicians' exposure to orchestral noise. Hearing acuity of the two groups was similar to some normal groups reported in the world literature but appeared poorer in comparison to some normal groups defined by a very restrictive definition of normal hearing. Issues relating to the definition of normal hearing are explored. A mathematical model descriptive of extended high tone hearing sensitivity for musicians and nonmusicians evaluated was calculated. The formula is presented from which typ...

Raised intracranial pressure is frequent in untreated nonsyndromic unicoronal synostosis and does not correlate with severity of phenotypic features.

Abstract: BACKGROUND In a small number of children with unicoronal synostosis, the phenotype is mild and the aesthetic benefit of surgical correction is potentially outweighed by surgical risk. Raised intracranial pressure, however, would necessitate intervention. The authors documented the incidence of raised intracranial pressure in children with mild features and/or parental reluctance to proceed directly to surgery. METHODS A retrospective review of all children with (1) a clinical diagnosis of nonsyndromic unicoronal synostosis; (2) unicoronal synostosis confirmed on computed tomographic scanning; (3) negative family history for unicoronal synostosis; and (4) negative genetic screening (including P250R encoded by FGFR3, exons IIIa and IIIc in FGFR2 and TWIST1) was completed. RESULTS Of the 80 children studied, seven (9 percent) underwent formal intracranial pressure monitoring because of a combination of mild clinical features (n = 4) and/or parental reluctance to proceed with surgery (n = 3). Intracranial pressure monitoring was reported as high in three (42 percent), borderline in two (29 percent), and normal in two patients (29 percent). The findings did not correlate with the degree of clinical deformation or age at presentation. There was little correlation with clinical and radiographic features of raised intracranial pressure in this genetically screened nonsyndromic group. CONCLUSIONS High or borderline raised intracranial pressure was present in five of seven cases. The risk did not correlate with degree of deformity or age at presentation. Formal intracranial pressure monitoring should be considered in all children with unicoronal synostosis not proceeding directly to surgical intervention, in combination with routine long-term follow-up and repeated intracranial pressure monitoring where indicated. CLINICAL QUESTION/LEVEL OF EVIDENCE Risk, V.

Peritoneal dialysis outcomes after temporary haemodialysis transfer for peritonitis

Abstract: Background There has not been a comprehensive examination to date of peritoneal dialysis (PD) outcomes after temporary haemodialysis (HD) transfer for peritonitis. Methods The study included all incident Australian patients who experienced peritonitis between 1 October 2003, and 31 December 2011, using Australia and New Zealand Dialysis and Transplant Registry data. Patients were grouped into three categories: Interim HD, Permanent HD and Never HD based on HD transfer status after the first peritonitis. The independent predictors of HD transfer and subsequent return to PD were determined by multivariable, multilevel mixed-effects logistic regression analysis. Matched case-control analyses were performed to compare clinical outcomes (e.g. patient survival) between groups. Results Of the 3305 patients who experienced peritonitis during the study period, 553 episodes (16.7%) resulted in transfer to HD and 101 patients subsequently returned to PD. HD transfer was significantly and independently predicted by inpatient treatment of peritonitis [odds ratio (OR) 11.45, 95% confidence interval (CI) 7.14-18.36] and the recovered microbiologic profile of organisms recognized to be associated with moderate (20-40%) to high (>40%) rates of catheter removal (moderate: OR 2.45, 95% CI 1.89-3.17; high: OR 8.63, 95% CI 6.44-11.57). Matched case-control analyses yielded comparable results among Interim, Permanent and Never HD groups in terms of patient survival (P = 0.28), death-censored technique survival [hazard ratio (HR) 0.87, 95% CI 0.59-1.28; P = 0.48] and peritonitis-free survival (HR 0.84, 95% CI 0.50-1.39, P = 0.49). Conclusions In an observational registry study of first peritonitis episodes, temporary HD transfer was not associated with inferior patient-level clinical outcomes when compared with others who either never required HD transfer or remained on HD permanently if all patient-level and peritonitis-related factors were considered equal. Therefore, return to PD after a temporary HD due to peritonitis should not be discouraged in appropriate PD patients.

A tRial Evaluating Mid Cut-Off Value Membrane Clearance of Albumin and Light Chains in HemoDialysis Patients: A Safety Device Study.

Abstract: Background: A new class of dialysis membrane, the mid cut-off (MCO) dialyzer, has been developed to improve the clearance of uremic toxins in hemodialysis (HD). The a tRial Evaluating Mid cut-Off Value membrane clearance of Albumin and Light chains in HemoDialysis patients (REMOVAL-HD) study aimed to determine if regular use of MCO dialyzer was safe and specifically did not result in a significant loss of albumin. Methods: This investigator initiated, crossover, longitudinal, device study was conducted across 9 centers in Australia and New Zealand (n = 89). Participants had a 4-week wash-in with high-flux HD, followed by 24-week intervention with MCO HD and a subsequent 4-week wash-out with high-flux HD. The primary outcome was change in serum albumin between weeks 4 and 28. Secondary outcomes included trends in serum albumin, changes in kappa- and lambda-free light chains (FLC), 6-min walk test (6MWT), malnutrition inflammation score (MIS), restless legs score and quality of life. Results: Participants had a mean age of 66 ± 14 years, 62% were men, 45% were anuric, and 51% had ­diabetes. There was no reduction in serum albumin following treatment with MCO HD (mean reduction –0.7 g/L, 95% CI –1.5 to 0.1). A sustained, unexplained reduction in serum albumin (>25%) was not observed in any participant. A reduction in FLC was observed 2 weeks into MCO HD (lambda-FLC: Δ –9.1 mg/L, 95% CI –14.4 to –3.7; kappa-FLC: Δ –5.7 mg/L, 95% CI –9.8 to –1.6) and was sustained for the rest of the study intervention. Both FLC increased after the cessation of MCO use. There was no improvement in restless legs symptoms, quality of life, 6MWT or MIS scores. Conclusions: Regular HD using the MCO dialyzer did not result in a significant fall in serum albumin. There were no effects on quality of life, functional status or nutrition. Trial Registration: Australian New Zealand Clinical Trials Registry Number (ANZCTRN) 12616000804482.

Initial sequencing and analysis of the human genome.

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.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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。

The social identity theory of intergroup behavior

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.