Showing papers by "David W. Johnson published in 2009"

An Educational Psychology Success Story: Social Interdependence Theory and Cooperative Learning

Abstract: The widespread and increasing use of cooperative learning is one of the great success stories of social and educational psychology. Its success largely rests on the relationships among theory, research, and practice. Social interdependence theory provides a foundation on which cooperative learning is built. More than 1,200 research studies have been conducted in the past 11 decades on cooperative, competitive, and individualistic efforts. Findings from these studies have validated, modified, refined, and extended the theory. From the theory, procedures for the teacher’s role in using formal and informal cooperative learning and cooperative base groups have been operationalized. Those procedures are widely used by educators throughout the world. The applications have resulted in revisions of the theory and the generation of new research.

Relationship between Dialysis Modality and Mortality

Abstract: Mortality differences between peritoneal dialysis (PD) and hemodialysis (HD) are widely debated. In this study, mortality was compared between patients treated with PD and HD (including home HD) using data from 27,015 patients in the Australia and New Zealand Dialysis and Transplant Registry, 25,287 of whom were still receiving PD or HD 90 d after entry into the registry. Overall mortality rates were significantly lower during the 90- to 365-d period among those being treated with PD at day 90 (adjusted hazard ratio [HR] 0.89; 95% confidence interval [CI] 0.81 to 0.99]; P < 0.001). This effect, however, varied in direction and size with the presence of comorbidities: Younger patients without comorbidities had a mortality advantage with PD treatment, but other groups did not. After 12 mo, the use of PD at day 90 was associated with significantly increased mortality (adjusted HR 1.33; 95% CI 1.24 to 1.42; P < 0.001). In a supplementary as-treated analysis, PD treatment was associated with lower mortality during the first 90 d (adjusted HR 0.67; 95% CI 0.56 to 0.81; P < 0.001). These data suggest that the effect of dialysis modality on survival for an individual depends on time, age, and presence of comorbidities. Treatment with PD may be advantageous initially but may be associated with higher mortality after 12 mo.

Energizing Learning: The Instructional Power of Conflict:

Abstract: Although intellectual conflict may be an important instructional tool (because of its potential constructive outcomes), conflict is rarely structured in instructional situations (because of its potential destructive outcomes). Many educators may be apprehensive about instigating intellectual conflict among students because of the lack of operational procedures to guide them. Ideally, operational procedures should be based on social science theory that is validated by research. Constructive controversy is an instructional procedure that is designed to create intellectual conflict among students and that meets these criteria. The authors of this article summarize the theory underlying constructive controversy and review the results of their meta-analysis of the validating research. The positive outcomes indicate that intellectual conflict can have important and positive effects on student learning and well-being.

Epinephrine and dexamethasone in children with bronchiolitis.

Abstract: Background Although numerous studies have explored the benefit of using nebulized epinephrine or corticosteroids alone to treat infants with bronchiolitis, the effectiveness of combining these medications is not well established. Methods We conducted a multicenter, double-blind, placebo-controlled trial in which 800 infants (6 weeks to 12 months of age) with bronchiolitis who were seen in the pediatric emergency department were randomly assigned to one of four study groups. One group received two treatments of nebulized epinephrine (3 ml of epinephrine in a 1:1000 solution per treatment) and a total of six oral doses of dexamethasone (1.0 mg per kilogram of body weight in the emergency department and 0.6 mg per kilogram for an additional 5 days) (the epinephrine–dexamethasone group), the second group received nebulized epinephrine and oral placebo (the epinephrine group), the third received nebulized placebo and oral dexamethasone (the dexamethasone group), and the fourth received nebulized placebo and or...

Frequencies of hepatitis B and C infections among haemodialysis and peritoneal dialysis patients in Asia-Pacific countries: analysis of registry data

Abstract: Background. The impact of dialysis modality on the rates and types of infectious complications has not been well studied. The aim of the present investigation was to evaluate the rates of hepatitis C virus (HCV) and hepatitis B virus (HBV) infections in peritoneal dialysis (PD) and haemodialysis (HD) patients in the Asia-Pacific region. Methods. The study included the most recent periodprevalent data recorded in the national or regional dialysis registries of the 10 Asia-Pacific countries/areas (Australia, NewZealand,Japan,China,Taiwan,Korea,Thailand,Hong Kong, Malaysia and India), where such data were available. Longitudinal data were also available for all incident Australian and New Zealand patients commencing dialysis between 1 April 1995 and 31 December 2005. Rates of HCV and HBV infections were compared by chi-square, Poisson regression and Kaplan–Meier survival analyses, as appropriate. Results. Data were obtained on 201 590 patients (HD 173 788; PD 27 802). HCV seroprevalences ranged between 0.7% and 18.1% across different countries and were generally higher in HD versus PD populations (7.9% ± 5.5% versus 3.0% ± 2.0%, P = 0.01). Seroconversion rates on dialysis were also significantly higher in HD patients (incidence rate ratio PD versus HD 0.33, 95% CI 0.13– 0.75). HCV infection was highly predictive of mortality in Japan (relative risk 1.37, 95% CI 1.15–1.62, P = 0.003) and in Australia and New Zealand (adjusted hazards ratio

Systems and methods for remote tracking and replay of user interaction with a webpage

Abstract: Systems and methods for monitoring user interaction with a remote computer are provided. More specifically, the systems and methods of the present invention allow for the remote tracking and replay of user interaction with a remote computer or webpage. One aspect of the invention allows user interaction data to be replayed on an embedded browser on a replay server. The replayed user interaction data may be converted to a video file to facilitate playback of the interaction data substantially independent of the replay server.

Length of time on peritoneal dialysis and encapsulating peritoneal sclerosis: position paper for ispd

Abstract: eritoneal dialysis (PD) is a successful dialysis modal-ity that enables patients with end-stage kidneydisease to have a home-based treatment with many ad-vantages for their quality of life In general, outcomes ofPD are equal to those of hemodialysis (HD) The reportedtechnique success of PD is, however, shorter than that ofHD Whereas there are “positive” reasons for droppingout, such as transplantation or recovery of renal function,some patients transfer to HD because of peritonitis, in-adequate small solute clearance and/or ultrafiltration,and social factors (1) The impact of adequacy and prob-lems with maintaining euvolemia as reasons for dropoutincrease over time, especially as residual renal functiondeclines Nevertheless, even anuric patients can be main-tained successfully on PD (2,3) Many patients are reluc-tant to transfer to HD, even when clinically indicated,because they perceive that such a transfer would ad-versely affect their quality of life A proper presentationof different renal replacement therapies from the startof treatment onward (integrated care) could potentiallyavoid disappointment when a transfer is neededOne of the potential, although infrequent, complica-tions of long-term PD is encapsulating peritoneal scle-rosis (EPS); it is associated with high morbidity relatedto bowel obstruction and malnutrition Reported mor-tality is around 50%, usually within 12 months of thediagnosis (4,5), although not all deaths are due to EPSitself (6) The first reports of EPS were from Japan andAustralia (4,7,8); more recently, there has been an in-creasing number of reports of EPS in Europe (9–11) Somenephrologists have suggested that there should be a timelimit to PD to prevent patients from developing this po-tentially devastating complicationThe principal aims of this paper are1 To review existing information about epidemiologyof EPS and its risk factors;2 To determine whether there are any predictors forthe development of EPS that would guide the deci-sion to stop PD and transfer to HD; and3 To reach a consensus that should be given tonephrologists and their patients about the lengthof time it is advisable to remain on PDGUIDELINES FOR EPSSo far, guidelines on the topic of EPS have been is-sued only by the Japanese Society for Peritoneal Dialy-sis (12) The UK guidelines are in the final process of

Frontorhiny, a Distinctive Presentation of Frontonasal Dysplasia Caused by Recessive Mutations in the ALX3 Homeobox Gene

Abstract: We describe a recessively inherited frontonasal malformation characterized by a distinctive facial appearance, with hypertelorism, wide nasal bridge, short nasal ridge, bifid nasal tip, broad columella, widely separated slit-like nares, long philtrum with prominent bilateral swellings, and midline notch in the upper lip and alveolus. Additional recurrent features present in a minority of individuals have been upper eyelid ptosis and midline dermoid cysts of craniofacial structures. Assuming recessive inheritance, we mapped the locus in three families to chromosome 1 and identified mutations in ALX3, which is located at band 1p13.3 and encodes the aristaless-related ALX homeobox 3 transcription factor. In total, we identified seven different homozygous pathogenic mutations in seven families. These mutations comprise missense substitutions at critical positions within the conserved homeodomain as well as nonsense, frameshift, and splice-site mutations, all predicting severe or complete loss of function. Our findings contrast with previous studies of the orthologous murine gene, which showed no phenotype in Alx3−/− homozygotes, apparently as a result of functional redundancy with the paralogous Alx4 gene. We conclude that ALX3 is essential for normal facial development in humans and that deficiency causes a clinically recognizable phenotype, which we term frontorhiny.

Mercury concentrations and pools in four Sierra Nevada forest sites, and relationships to organic carbon and nitrogen

Abstract: . This study presents data on mercury (Hg) concentrations, stochiometric relations to carbon (C) and nitrogen (N), and Hg pool sizes in four Sierra Nevada forest sites of similar exposure and precipitation regimes, and hence similar atmospheric deposition, to evaluate how ecosystem parameters control Hg retention in ecosystems. In all four sites, the largest amounts of Hg reside in soils which account for 94–98% of ecosystem pools. Hg concentrations and Hg/C ratios increase in the following order: Green Needles/Leaves Mineral soil layers show strong positive correlations of Hg to C across all sites and soil horizons (r2=0.83), but Hg concentrations are even more closely related to N with a similar slope to that observed in litter (r2=0.92). Soil N levels alone explain over 90% of Hg pool sizes across the four Sierra Nevada forest sites. This suggests that soil organic N and C groups provide sorption sites for Hg to retain atmospheric deposition. However, the patterns could be due to indirect relationships where high soil N and C levels reflect high ecosystem productivity which leads to corresponding high atmospheric Hg deposition inputs via leaf litterfall and plant senescence. Our results also show that two of the sites previously affected by prescribed burning and wildfires show significant depletion of above-ground Hg pools but that belowground Hg pools remain unaffected. We conclude that sequestration of Hg in remote Sierra Nevada forest sites is strongly co-determined by ecosystem parameters with C and N pools being excellent determinants for the pool sizes of Hg.

Pseudomonas peritonitis in Australia: predictors, treatment, and outcomes in 191 cases.

Abstract: Design, setting, participants, & measurements: The predictors, treatment, and clinical outcomes of Pseudomonas peritonitis were examined by binary logistic regression and multilevel, multivariate Poisson regression in all Australian PD patients in 66 centers between 2003 and 2006. Results: A total of 191 episodes of Pseudomonas peritonitis (5.3% of all peritonitis episodes) occurred in 171 individuals. Its occurrence was independently predicted by Maori/Pacific Islander race, Aboriginal/Torres Strait Islander race, and absence of baseline peritoneal equilibration test data. Compared with other organisms, Pseudomonas peritonitis was associated with greater frequencies of hospitalization (96 versus 79%; P = 0.006), catheter removal (44 versus 20%; P < 0.001), and permanent hemodialysis transfer (35 versus 17%; P < 0.001) but comparable death rates (3 versus 2%; P = 0.4). Initial empiric antibiotic choice did not influence outcomes, but subsequent use of dual anti-pseudomonal therapy was associated with a lower risk for permanent hemodialysis transfer (10 versus 38%, respectively; P = 0.03). Catheter removal was associated with a lower risk for death than treatment with antibiotics alone (0 versus 6%; P < 0.05). Conclusions: Pseudomonas peritonitis is associated with high rates of catheter removal and permanent hemodialysis transfer. Prompt catheter removal and use of two anti-pseudomonal antibiotics are associated with better outcomes.

Lower limit to the lattice thermal conductivity of nanostructured Bi2Te3-based materials

Abstract: We investigate the lower limit to the lattice thermal conductivity of Bi2Te3 and related materials using thin films synthesized by the method of elemental reactants. The thermal conductivities of single layer films of (Bi0.5Sb0.5)2Te3 and multilayer films of (Bi2Te3)m(TiTe2)n and [(BixSb1−x)2Te3]m(TiTe2)n are measured by time-domain thermoreflectance; the thermal conductivity data are compared to our prior work on nanocrystalline Bi2Te3 and a Debye–Callaway model of heat transport by acoustic phonons. The homogeneous nanocrystalline films have average grain sizes 30

Association of Dialysis Modality and Cardiovascular Mortality in Incident Dialysis Patients

Abstract: Background and objectives: The aim of the investigation presented here was to compare the rates, causes, and timing of cardiovascular (CV) death in incident peritoneal dialysis (PD) and hemodialysis (HD) patients. Design, setting, participants, & measurements: The study included all adult Australian and New Zealand patients commencing dialysis between January 1, 1997 and December 31, 2007. Rates of and times to CV death were compared by incident rate ratios, cumulative incidence, and multivariable Cox proportional hazards model analyses. Dialysis modality was included in the model as a time-varying covariate, and a competing risks approach was used to obtain cause-specific hazard ratios. Results: Of the 24,587 patients who commenced dialysis (first treatment PD n = 6521; HD n = 18,066) during the study, 5669 (21%) died from CV causes [PD 2044 (28%) versus HD 3625 (21%)]. The incidence rates of CV mortality in PD and HD patients were 9.99 and 7.96 per 100 patient-years, respectively (incidence rate ratio PD versus HD, 1.25; 95% confidence interval 1.12 to 1.32). PD was consistently associated with an increased hazard of CV death compared with HD after 1 yr of treatment. This increased risk in PD patients was largely accounted for by an increased risk of death due to myocardial infarction. Conclusions: Dialysis modality is significantly associated with the risk, causes, and timing of CV death experienced by ESRD patients in Australia and New Zealand.

Turnover of labile and recalcitrant soil carbon differ in response to nitrate and ammonium deposition in an ombrotrophic peatland

Abstract: The effects of 4 years of simulated nitrogen deposition, as nitrate (NO3 ) and ammonium (NH4 1), on microbial carbon turnover were studied in an ombrotrophic peatland. We investigated the mineralization of simple forms of carbon using MicroRespt measurements (a multiple substrate induced respiration technique) and the activities of four soil enzymes involved in the decomposition of more complex forms of carbon or in nutrient acquisition: Nacetyl- glucosaminidase (NAG), cellobiohydrolase (CBH), acid phosphatase (AP), and phenol oxidase (PO). The potential mineralization of labile forms of carbon was significantly enhanced at the higher N additions, especially with NH4 1 amendments, while potential enzyme activities involved in breakdown of more complex forms of carbon or nutrient acquisition decreased slightly (NAG and CBH) or remained unchanged (AP and PO) with N amendments. This study also showed the importance of distinguishing between NO3 and NH4 1 amendments, as their impact often differed. It is possible that the limited response on potential extracellular enzyme activity is due to other factors, such as limited exposure to the added N in the deeper soil or continued suboptimal functioning of the enzymes due to the low pH, possibly via the inhibitory effect of low phenol oxidase activity.

Practice variations in the treatment of febrile infants among pediatric emergency physicians.

Abstract: OBJECTIVES The objectives of this study were to characterize variations in treatment decisions for young febrile infants in pediatric emergency departments across Canada and to document the extent of practice variations among pediatric emergency department practitioners. METHODS This was a prospective, concurrent, cohort study of consecutive infants up to 90 days of age who presented to 6 pediatric emergency departments in Canada with fever (rectal temperature of >or=38.0 degrees C). We recorded information in the emergency department and contacted the families by telephone to confirm the final disposition. RESULTS A total of 257 infants were recruited over 2 to 4 months. Patients were similar across centers in terms of gestational age and weight, chronologic age at arrival, weight, and gender. Temperatures measured at home and during triage and durations of fever also were similar among centers. In one center, significantly more children arrived with cough; in another center, fewer parents reported sick contacts at home. Rates of blood and urine testing were not significantly different across sites, but rates of lumbar puncture, respiratory virus testing, and chest radiography were different. A total of 55% of infants received antibiotics, and significant practice variations in the numbers and types of antibiotics used were documented. CONCLUSIONS Practices in the evaluation of young infants with fever in tertiary pediatric emergency departments varied substantially. Blood and urine tests were ordered in the majority of centers, but rates of cerebrospinal fluid testing and antibiotic treatment differed across centers.

Reciprocal carbon and nitrogen transfer between an ericaceous dwarf shrub and fungi isolated from Piceirhiza bicolorata ectomycorrhizas.

Abstract: Summary • The overstorey coniferous trees and understorey ericaceous dwarf shrubs of northern temperate and boreal forests have previously been considered to form mycorrhizas with taxonomically and functionally distinct groups of fungi.  Here, we tested the hypothesis that Meliniomyces variabilis and Meliniomyces bicolor, isolated from Piceirhiza bicolorata ectomycorrhizas of pine, can function as ericoid mycorrhizal symbionts with Vaccinium vitis-idaea. We used split-compartment microcosms to measure the reciprocal exchange of 13 C and 15 N between V. vitisidaea and three fungal isolates in the Hymenoscyphus ericae aggregate isolated from Scots pine ectomycorrhizas (M. variabilis and M. bicolor) or Vaccinium roots (M. variabilis).  The extramatrical fungal mycelium of labelled mycorrhizal plants was significantly enriched in 13 C, and the leaves were significantly enriched in 15 N, compared with nonmycorrhizal and nonlabelled controls.  These findings show for the first time that fungi in the H. ericae aggregate, isolated from pine ectomycorrhizas, can transfer C and N and can thus form functional ericoid mycorrhizas in an understorey ericaceous shrub.

A 4-year review of pediatric mental health emergencies in Alberta.

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.

Reoperation for intracranial hypertension in TWIST1-confirmed Saethre-Chotzen syndrome: a 15-year review.

Abstract: BACKGROUND: Saethre-Chotzen syndrome is a syndromic craniosynostosis defined by a genetic mutation affecting the TWIST1 gene on chromosome 7p21. It is typically associated with unicoronal or bicoronal synostosis, eyelid ptosis, dysmorphic external ears, and other variable facial and limb abnormalities. Surgical management of the craniosynostosis addresses the calvarial deformity and may relieve or reduce the risk of intracranial hypertension. The aim of this study was to assess surgical intervention, with particular consideration of the reoperation rate for intracranial hypertension, in Saethre-Chotzen syndrome patients. METHODS: A retrospective case note analysis was performed on all patients with a confirmed TWIST1 gene abnormality who attended the Oxford Craniofacial Unit over a 15-year period. Each patient's mutation and clinical features were recorded. Surgical intervention and sequelae were examined in greater detail. RESULTS: Thirty-four patients with genetically confirmed Saethre-Chotzen syndrome were identified. All had craniosynostosis (bicoronal, 76 percent; unicoronal, 18 percent; bicoronal and sagittal, 6 percent), and the majority had eyelid ptosis, low frontal hairline, and external ear anomalies. Thirty-one patients had received surgical intervention. Nine of 26 patients (35 percent) with at least 12 months of follow-up after primary intervention and eight of 19 patients (42 percent) with at least 5 years of follow-up developed intracranial hypertension necessitating secondary calvarial surgery. CONCLUSIONS: Despite standard surgical intervention, patients with Saethre-Chotzen syndrome have a high rate (35 to 42 percent) of recurrent intracranial hypertension necessitating further surgical expansion. All patients with either bicoronal synostosis or unicoronal synostosis with syndromic features should be screened for TWIST1 mutations, as this confers a greater risk than nonsyndromic synostosis of the same sutures. Regular follow-up throughout the childhood years is essential.

Streptococcal peritonitis in Australian peritoneal dialysis patients: predictors, treatment and outcomes in 287 cases

Abstract: There has not been a comprehensive, multi-centre study of streptococcal peritonitis in patients on peritoneal dialysis (PD) to date. The predictors, treatment and clinical outcomes of streptococcal peritonitis were examined by binary logistic regression and multilevel, multivariate poisson regression in all Australian PD patients involving 66 centres between 2003 and 2006. Two hundred and eighty-seven episodes of streptococcal peritonitis (4.6% of all peritonitis episodes) occurred in 256 individuals. Its occurrence was independently predicted by Aboriginal or Torres Strait Islander racial origin. Compared with other organisms, streptococcal peritonitis was associated with significantly lower risks of relapse (3% vs 15%), catheter removal (10% vs 23%) and permanent haemodialysis transfer (9% vs 18%), as well as a shorter duration of hospitalisation (5 vs 6 days). Overall, 249 (87%) patients were successfully treated with antibiotics without experiencing relapse, catheter removal or death. The majority of streptococcal peritonitis episodes were treated with either intraperitoneal vancomycin (most common) or first-generation cephalosporins for a median period of 13 days (interquartile range 8–18 days). Initial empiric antibiotic choice did not influence outcomes. Streptococcal peritonitis is a not infrequent complication of PD, which is more common in indigenous patients. When treated with either first-generation cephalosporins or vancomycin for a period of 2 weeks, streptococcal peritonitis is associated with lower risks of relapse, catheter removal and permanent haemodialysis transfer than other forms of PD-associated peritonitis.

An in vitro investigation of herbs traditionally used for kidney and urinary system disorders: potential therapeutic and toxic effects.

Abstract: SUMMARY: Aim: Renal fibrosis is central to progression of most chronic renal pathologies. Antioxidants that protect the tubular epithelium and anti-fibrotics that induce apoptosis of pro-fibrotic myofibroblasts without adversely affecting tubular epithelium may slow progression of renal fibrosis, while toxic substances may exacerbate renal scarring. We investigated 47 herbs for their in vitro toxic or antioxidant effects on normal renal mammalian fibroblasts (NRK49F) and tubular epithelial cells (NRK52E) to determine their potential value as therapeutic agents in renal fibrosis involving oxidative stress. Methods: Herbs were chosen because of their traditional use in kidney or urinary system disorders, or because of recent published interest in their therapeutic or toxic potential in kidney disease. Extracts of herbs were made using a sequential multi-solvent extraction process. Each extract was analysed separately. Extraction solvents were ethyl acetate, methanol and 50% aqueous methanol. Cells were treated with extracts with/without oxidative stress (1.0 mM hydrogen peroxide). Cellular changes (apoptosis, necrosis, mitosis, transdifferentiation) were identified and quantified using defined criteria. Results: All extracts of Dioscorea villosa showed significant toxicity to both cell lines. At low concentrations (5‐50 mg/mL) they induced epithelial to mesenchymal transdifferentiation, as demonstrated by increased immunohistochemistry staining for a-smooth muscle actin and transforming growth factor-b1 in treated versus control cells. Angelica sinensis, Centella asiatica, Glycyrrhiza glabra, Scutellaria lateriflora, and Olea europaea demonstrated strong antioxidant effects in epithelial cells and/or apoptotic effects on fibroblasts. Conclusion: This investigation has revealed renotoxicity of D. villosa and anti-fibrotic, oxidant potential of several herbal extracts, all of which require further study.

Corynebacterium peritonitis in Australian peritoneal dialysis patients: predictors, treatment and outcomes in 82 cases

Abstract: Background. Infection due to Corynebacterium species has been reported with increasing frequency over recent decades. The impacts of enhanced laboratory detection together with widespread use of new peritoneal dialysis (PD) connection technology and antimicrobial prophylaxis strategies on Corynebacterium PD-associated peritonitis have not been well studied. Methods. We investigated the frequency, predictors, treatment and clinical outcomes of Corynebacterium peritonitis in all Australian adult patients involving 66 centres who were receiving PD between 1 October 2003 and 31 December 2006. Results. Eighty-two episodes of Corynebacterium peritonitis (2.3% of all peritonitis episodes) occurred in 65 (1.4%) PD patients. Ten (15%) patients experienced more than one episode of Corynebacterium peritonitis and additional organisms were isolated in 12 (15%) episodes of Corynebacterium peritonitis. The incidence of Corynebacterium peritonitis was significantly and independently predicted only by BMI: RR 2.72 (95% CI 1.38–5.36) for the highest tertile BMI compared with the lowest tertile. The overall cure rate with antibiotics alone was 67%, which was similar to that of peritonitis due to other organisms. Vancomycin was the most common antimicrobial agent administered in the initial empiric and subsequent antibiotic regimens, although outcomes were similar regardless of antimicrobial schedule. Corynebacterium peritonitis not infrequently resulted in relapse (18%), repeat peritonitis (15%), hospitalization (70%), catheter removal (21%), permanent haemodialysis transfer (15%) and death (2%). The individuals who had their catheters removed more than 1 week after the onset of Corynebacterium peritonitis had a significantly higher risk of permanent haemodialysis transfer than those who had their catheters removed within 1 week (90% versus 43%, P < 0.05). Conclusions. Corynebacterium is an uncommon but significant cause of PD-associated peritonitis. Complete cure with antibiotics alone is possible in the majority of patients, and rates of adverse outcomes are comparable to those seen with peritonitis due to other organisms. Use of vancomycin rather than cephazolin as empiric therapy does not impact outcomes, and a 2-week course of antibiotic therapy appears sufficient. If catheter removal is required, outcomes are improved by removing the catheter within 1 week of peritonitis onset.

Isolation and primary culture of human proximal tubule cells.

Abstract: Primary cultures of renal proximal tubule cells (PTC) have been widely used to investigate tubule cell function. They provide a model system where confounding influences of renal haemodynamics, cell heterogeneity, and neural activity are eliminated. Additionally they are likely to more closely resemble PTC in vivo than established kidney cell lines, which are often virally immortalised and are of uncertain origin. This chapter describes a method used in our laboratories to isolate and culture pure populations of human PTC. The cortex is dissected away from the medulla and minced finely. Following collagenase digestion, the cells are passed through a sieve and separated on a Percoll density gradient. An almost pure population of tubule fragments form a band at the base of the gradient. Cultured in a hormonally defined serum-free growth media, they form a tightly packed monolayer that retains the differentiated characteristics of PTC for up to three passages.

Relationship Among Cooperative Learning Experiences, Social Interdependence, Children’s Aggression, Victimization, and Prosocial Behaviors

Abstract: This study examined the relationships among cooperative experiences, social interdependence predispositions, harm-intended aggression, victimization, and prosocial behaviors with 217 elementary school children from the 3rd to 5th grades. Path analysis using LISREL indicate that cooperative experiences predicted cooperative predispositions, the absence of individualistic predispositions, and prosocial behaviors. Cooperative predisposition predicted prosocial behaviors and the absence of harm-intended aggression. Competitive predisposition predicted harm-intended aggression. The implications of increasing cooperativeness through cooperative experiences, especially for bullies and victims, were discussed.