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A J Morris

Publications and source records attributed to A J Morris.

At least 55 records · Page 3Linked to original sources
PubMed2001

Prospective study of 125 cases of Staphylococcus aureus bacteremia in children in New Zealand.

BACKGROUND: Staphylococcus aureus bacteremia is a common complication of S. aureus infection. There are few pediatric studies defining the incidence and associated morbidity and mortality of S. aureus bacteremia and no such New Zealand studies. We conducted a prospective study of S. aureus bacteremia in children in New Zealand. METHODS: From July 1, 1996 to December 31, 1998, we included all children < 16 years of age with S. aureus bacteremia in Auckland and Christchurch. Relevant information regarding patient demographics, clinical course and outcome and laboratory results was recorded. RESULTS: One hundred twenty-five cases of true S. aureus bacteremia were identified. There were 4 deaths within 30 days of the onset of bacteremia. Fourteen (11%) of the children were < 1 month of age. Maori children (relative risk, 2.0; 95% confidence interval, 1.3 to 3.2) were twice as likely and Pacific Island children (relative risk, 2.5; 95% confidence interval, 1.6 to 3.8) 2.5 times as likely as white children to acquire S. aureus bacteremia. The peak incidence of S. aureus bacteremia was observed in Pacific Island children < 1 year of age (105 cases/100,000 children/year). Twenty-seven percent of cases were related to intravenous catheters. Seventy percent of cases were community-acquired. Ninety-eight percent of non-catheter-related cases in children > 1 month of age were community-acquired. There was a low rate of methicillin resistance (6%). CONCLUSIONS: S. aureus bacteremia is largely community-acquired in children in New Zealand and is more common in Pacific Island and Maori populations. Although there is a low associated mortality, a significant number are potentially preventable cases secondary to intravenous catheters.

Adolescent↗
PubMed2001

Role of p38 MAP kinase in diperoxovanadate-induced phospholipase D activation in endothelial cells.

We previously demonstrated that diperoxovanadate (DPV), a synthetic peroxovanadium compound and cell-permeable oxidant that acts as a protein tyrosine phosphatase inhibitor and insulinomimetic, increased phospholipase D (PLD) activation in endothelial cells (ECs). In this report, the regulation of DPV-induced PLD activation by mitogen-activated protein kinases (MAPKs) was investigated. DPV activated extracellular signal-regulated kinase, c-Jun NH2-terminal kinase (JNK), and p38 MAPK in a dose- and time-dependent fashion. Treatment of ECs with p38 MAPK inhibitors SB-203580 and SB-202190 or transient transfection with a p38 dominant negative mutant mitigated the PLD activation by DPV but not by phorbol ester. SB-202190 blocked DPV-mediated p38 MAPK activity as determined by activated transcription factor-2 phosphorylation. Immunoprecipitation of PLD from EC lysates with PLD1 and PLD2 antibodies revealed both PLD isoforms associated with p38 MAPK. Similarly, PLD1 and PLD2 were detected in p38 immunoprecipitates from control and DPV-challenged ECs. Binding assays demonstrated interaction of glutathione S-transferase-p38 fusion protein with PLD1 and PLD2. Both PLD1 and PLD2 were phosphorylated by p38 MAPK in vitro, and DPV increased phosphorylation of PLD1 and PLD2 in vivo. However, phosphorylation of PLD by p38 failed to affect PLD activity in vitro. These results provide evidence for p38 MAPK-mediated regulation of PLD in ECs.

Animals↗
PubMed2001

Prospective study of 424 cases of Staphylococcus aureus bacteraemia: determination of factors affecting incidence and mortality.

BACKGROUND: Staphylococcus aureus bacteraemia (SAB) is a common complication of S. aureus infection and is associated with a high mortality. AIMS: To document prospectively the pattern of illness associated with SAB in New Zealand and, by recording patient demographic factors and clinical features, to identify risk factors associated with a poor outcome. METHODS: From 1 July 1996 to 31 December 1997, adults with SAB were prospectively studied in six tertiary care hospitals. All information obtained from patients' records was recorded on worksheets and transferred to a computerized spreadsheet for analysis. RESULTS: There were 424 patients with SAB. Maori (relative risk (RR)= 1.8, 95% confidence interval (CI) = 1.3-2.6) and Pacific Island people (RR = 4.0, 95% CI = 3.1-5.3) were significantly more likely than people of European descent to acquire SAB, but not to die from the infection. Fifty per cent of cases were community acquired. A source was identified for 85%: intravenous catheter (31%), primarily hospital acquired, and skin/soft tissue (22%), primarily community acquired, were the most common foci. The 30-day mortality was 19%, 83% of whom died within 2 weeks. Risk factors for a poor outcome were: increasing age above 60, female sex (RR = 1.4, 95% CI = 1.0-2.1), diabetes mellitus (RR = 1.5, 95% CI = 1.0-2.4), immunosuppression (RR = 1.5, 95% CI = 1.0-2.4), pre-existing renal impairment (RR = 1.8, 95% CI = 1.2-2.7), malignancy (RR= 2.2, 95% CI = 1.4-3.5), lung as a source (RR = 2.8, 95% CI = 1.9-4.2) and unknown source (RR = 2.3, 95% CI = 1.5-3.3). Mortality was also accurately predicted by two multifactor scoring systems. There was a low rate of methicillin resistance (5%). CONCLUSIONS: Staphylococcus aureus bacteraemia is more likely to occur in certain ethnic groups, while mortality is associated with other identifiable risk factors and continues to be high. Intravenous catheters remain the most common and most preventable cause of SAB.

Adolescent↗
PubMed2000

Synucleins are a novel class of substrates for G protein-coupled receptor kinases.

G protein-coupled receptor kinases (GRKs) specifically recognize and phosphorylate the agonist-occupied form of numerous G protein-coupled receptors (GPCRs), ultimately resulting in desensitization of receptor signaling. Until recently, GPCRs were considered to be the only natural substrates for GRKs. However, the recent discovery that GRKs also phosphorylate tubulin raised the possibility that additional GRK substrates exist and that the cellular role of GRKs may be much broader than just GPCR regulation. Here we report that synucleins are a novel class of GRK substrates. Synucleins (alpha, beta, gamma, and synoretin) are 14-kDa proteins that are highly expressed in brain but also found in numerous other tissues. alpha-Synuclein has been linked to the development of Alzheimer's and Parkinson's diseases. We found that all synucleins are GRK substrates, with GRK2 preferentially phosphorylating the alpha and beta isoforms, whereas GRK5 prefers alpha-synuclein as a substrate. GRK-mediated phosphorylation of synuclein is activated by factors that stimulate receptor phosphorylation, such as lipids (all GRKs) and Gbetagamma subunits (GRK2/3), suggesting that GPCR activation may regulate synuclein phosphorylation. GRKs phosphorylate synucleins at a single serine residue within the C-terminal domain. Although the function of synucleins remains largely unknown, recent studies have demonstrated that these proteins can interact with phospholipids and are potent inhibitors of phospholipase D2 (PLD2) in vitro. PLD2 regulates the breakdown of phosphatidylcholine and has been implicated in vesicular trafficking. We found that GRK-mediated phosphorylation inhibits synuclein's interaction with both phospholipids and PLD2. These findings suggest that GPCRs may be able to indirectly stimulate PLD2 activity via their ability to regulate GRK-promoted phosphorylation of synuclein.

Amino Acid Sequence↗
PubMed2000

Role of phosphatidic acid phosphatase 2a in uptake of extracellular lipid phosphate mediators.

Phosphatidic acid (PA) phosphatase 2a (PAP2a) is an integral membrane glycoprotein that hydrolyzes a number of structurally related lipid phosphate substrates when presented in mixed phospholipid and detergent micelles. The physiological substrate specificity and functions of this enzyme are unclear. Using reconstitution studies we demonstrate that PAP2a hydrolyses both PA and LysoPA substrates in a lipid bilayer. To investigate the activity of PAP2a against cellular substrates we generated HEK293 cell variants stably overexpressing the enzyme. Although one of these lines exhibited a 27-fold increase in PAP2 activity measured in vitro, levels of PA were not significantly reduced in comparison with control cells. Cell surface labeling and activity measurements demonstrate that a portion of the enzyme was localized to the cell surface. Pagano and Longmuir (J. Biol. Chem. 260 (1985) 1909) described the rapid uptake of PA by cultured cells, but the mechanisms and proteins involved were not identified. We found that overexpression of PAP2a was accompanied by a 2.1-fold increase in uptake of a fluorescent PA analog but that uptake of other phospholipids and diacylglycerols was unaltered. The increase in lipid uptake was completely dependent on PAP activity and unaffected by endocytosis inhibitors. Our results indicate that PAP2a is a cell surface enzyme that plays an active role in the hydrolysis and uptake of lipids from the extracellular space.

Cell Line↗
PubMed2000

Antimicrobial resistance and clinical outcome of Bacteroides bacteremia: findings of a multicenter prospective observational trial.

There is debate regarding the correlation between in vitro susceptibility testing and clinical response to therapy for Bacteroides bacteremia. We conducted a prospective multicenter observational study of 128 patients with bacteroides bacteremia. Outcome was correlated with results of in vitro susceptibility testing of Bacteroides isolates recovered from blood and/or nonblood sites, determined with use of 3 end points: mortality at 30 days, clinical response (cure vs. failure), and microbiological response (eradication vs. persistence). The mortality rate among patients who received inactive therapy (45%) was higher than among patients who received active therapy (16%; P=.04). Clinical failure (82%) and microbiological persistence (42%) were higher for patients who received inactive therapy than for patients who received active therapy (22% and 12%, respectively; P=.0002 and.06, respectively). In vitro activity of agents directed at Bacteroides species reliably predicts outcome: the specificity was 97%, and positive predictive value was 82%. Antimicrobial susceptibility testing may be indicated for patients whose blood specimens yield Bacteroides species.

Adolescent↗
PubMed2000

Nosocomial blood stream infection in Auckland Healthcare hospitals.

AIM: To report the epidemiology of nosocomial bloodstream infections in Auckland Healthcare Hospitals. METHODS: From January 1995 to December 1997 every positive blood culture result was followed up by an infection control nurse who recorded relevant clinical, laboratory and treatment information on a data collection sheet. The clinical significance of each isolate was determined and the most likely source recorded. RESULTS: During the three year study period, there were 1,046 nosocomial blood stream infections yielding 1,147 isolates. The most common isolates/groups were: coagulase negative staphylococci 19%, S. aureus 18%, E. coli 12%, streptococci 10%, other Enterobacteriaceae 10%, Enterobacter spp. 7%, Pseudomonas spp. 5%, anaerobes 2%, and yeasts 4%. The most common sources were: intravascular lines 40%, urinary tract 8%, skin/soft tissue 8%, gastrointestinal 7%, and unknown 25%. The overall results were strongly influenced by the neonatal intensive care unit at National Women's Hospital where 58% of blood stream infections had intravascular-lines as the source and 53% of the isolates were coagulase negative staphylococci. The overall blood stream infection rate was approximately 6/1,000 admissions. Rates per 1,000 inpatient days for haematology, intensive care, oncology, neonatal and all other patients were 13, 11, 3, 3 and 1 respectively. CONCLUSIONS: Surveillance data that are clinically relevant are useful in identifying areas where infection prevention strategies can be implemented. Because of the importance of lines as a source of nosocomial blood stream infections all aspects of line care are being reviewed with the aim of reducing these devices as a source of blood stream infection.

Cross Infection↗
PubMed2000

Fluorescently labeled neomycin as a probe of phosphatidylinositol-4, 5-bisphosphate in membranes.

Phosphatidylinositol-4,5-bisphosphate (PI(4,5)P(2)), a minor component of the plasma membrane, is important in signal transduction, exocytosis, and ion channel activation. Thus fluorescent probes suitable for monitoring the PI(4,5)P(2) distribution in living cells are valuable tools for cell biologists. We report here three experiments that show neomycin labeled with either fluorescein or coumarin can be used to detect PI(4,5)P(2) in model phospholipid membranes. First, addition of physiological concentrations of PI(4,5)P(2) (2%) to lipid vesicles formed from mixtures of phosphatidylcholine (PC) and phosphatidylserine (PS) enhances the binding of labeled neomycin significantly (40-fold for 5:1 PC/PS vesicles). Second, physiological concentrations of inositol-1,4,5-trisphosphate (10 microM I(1,4,5)P(3)) cause little translocation of neomycin from PC/PS/PI(4,5)P(2) membranes to the aqueous phase, whereas the same concentrations of I(1,4,5)P(3) cause significant translocation of the green fluorescent protein/phospholipase C-delta pleckstrin homology (GFP-PH) constructs from membranes (Hirose et al., Science, 284 (1999) 1527). Third, fluorescence microscopy observations confirm that one can distinguish between PC/PS vesicles containing either 0 or 2% PI(4, 5)P(2) by exposing a mixture of the vesicles to labeled neomycin. Thus fluorescently labeled neomycin could complement GFP-PH constructs to investigate the location of PI(4,5)P(2) in cell membranes.

Acetates↗
PubMed2000

A school and community outbreak of tuberculosis in Auckland.

AIM: To describe a school and community outbreak of tuberculosis in South Auckland in 1997/8. METHODS: Cases were diagnosed according to national guidelines at Middlemore, Green Lane and Starship Hospitals. Public health follow-up was conducted by Auckland Healthcare. RESULTS: Twelve cases were diagnosed during the outbreak. Nine cases were from the same South Auckland secondary school; six reported no association outside school. Three cases were in younger children who had close household contact with two of the school cases. Nine cases (including eight from the school) had identical Mycobacterium tuberculosis isolates on restriction fragment length polymorphism testing. No microbiological culture was obtained from the three remaining cases. Contact investigation detected five of the cases. Chemoprophylaxis was prescribed for twenty-six school students, two adult staff, and nine household contacts. CONCLUSION: This is the first published account of a tuberculosis outbreak in a New Zealand school setting for decades. Recognition of the outbreak was delayed. DNA fingerprinting played a valuable role in the investigation. The source case may have been a school student. The social impact of the outbreak and preventability with routine adolescent BCG vaccination are discussed.

Adolescent↗
PubMed2000

Clinical manifestations and molecular epidemiology of late recurrent candidemia, and implications for management.

The aim of this study was to define the epidemiology and clinical manifestations of late recurrent candidemia. For this purpose, late recurrent candidemia was defined as an episode of candidemia occurring at least 1 month after the apparent complete resolution of an infectious episode caused by the same Candida sp. A total of five patients with recurrent candidemia were investigated. For all patients, isolates from the initial and recurrent episodes of candidemia were available for in vitro susceptibility testing and genetic characterization by DNA-based techniques. The results revealed the following salient features: prolonged duration between the initial and recurrent episodes (range, 1-8 months); recurrence of candidemia despite anti-fungal therapy; importance of retained intravascular catheters, neutropenia, and corticosteroids as factors predisposing to recurrence; high morbidity and mortality; no emergence of antifungal drug resistance between the initial and recurrent episodes; and relapse of infection due to the original infecting strain, rather than reinfection with a new strain. These findings raise several issues about the management and follow-up of patients with candidemia, which require assessment in future studies.

Aged↗
PubMed2000

Basement membrane peptides as markers of liver disease in chronic hepatitis C.

BACKGROUND/AIM: Chronic hepatitis C is characterised by slow progression to liver fibrosis. In liver fibrosis, basement membrane components are increasingly deposited around the vessels and in the portal tracts. Serum assays can measure the two major components of the basement membrane, type IV collagen and laminin. The aim of this study was to determine whether serum levels of type IV collagen and laminin are related to severity of liver injury in chronic hepatitis C. METHODS: Thirty-seven patients with chronic hepatitis C (CHC) and five healthy controls were studied. Serum type IV collagen was measured by a one-step sandwich EIA kit (Fuji, Japan) and serum laminin was measured by RIA (CIS, UK). Liver biopsies in patients with CHC were scored using a previously described grading and staging system. Liver biopsy scores were compared to serum levels of laminin, type IV collagen and alanine aminotransferase (ALT). Receiver operating characteristic (ROC) analysis was used to compare the ability of the assays to detect advanced liver injury. RESULTS: The median serum concentration of type IV collagen was 127.1 ng/ml (range 17.7 to 317.4) in CHC patients compared to a median of 61.3 ng/ml (range 11.5 to 102.3) in controls, p=0.006. The median serum concentration of laminin was 1.12 U/ml (range 0.74 to 2.46) in CHC compared to a median of 0.87 U/ml (range 0.83 to 1.06) in controls, p=0.07. Both serum type IV collagen and laminin were significantly correlated with the fibrotic stage and also with the necroinflammatory injury scores- histological activity index, portal inflammation and periportal hepatitis. Serum ALT was significantly correlated with portal inflammation. Using ROC analysis, the area under the curve for type IV collagen and laminin was 0.83 (p=0.001) and 0.82 (p=0.0017), respectively, while the area under the curve for ALT was 0.54 (p=0.1). CONCLUSIONS: Serum assays of basement membrane peptides are accurate non-invasive markers of liver fibrosis and liver inflammation in chronic hepatitis C. These markers are superior to serum ALT in reflecting liver injury and they have high specificity and sensitivity in detecting advanced liver disease in chronic hepatitis C.

Basement Membrane↗
PubMed2000

Dual requirement for rho and protein kinase C in direct activation of phospholipase D1 through G protein-coupled receptor signaling.

G protein-coupled and tyrosine kinase receptor activation of phospholipase D1 (PLD1) play key roles in agonist-stimulated cellular responses such as regulated exocytosis, actin stress fiber formation, and alterations in cell morphology and motility. Protein Kinase C, ADP-ribosylation factor (ARF), and Rho family members activate PLD1 in vitro; however, the actions of the stimulators on PLD1 in vivo have been proposed to take place through indirect pathways. We have used the yeast split-hybrid system to generate PLD1 alleles that fail to bind to or to be activated by RhoA but that retain wild-type responses to ARF and PKC. These alleles then were employed in combination with alleles unresponsive to PKC or to both stimulators to examine the activation of PLD1 by G protein-coupled receptors. Our results demonstrate that direct stimulation of PLD1 in vivo by RhoA (and by PKC) is critical for significant PLD1 activation but that PLD1 subcellular localization and regulated phosphorylation occur independently of these stimulatory pathways.

ADP-Ribosylation Factor 1↗
PubMed2000

Simple and inexpensive but highly discriminating method for computer-assisted DNA fingerprinting of Pseudomonas aeruginosa.

We describe here a method for computer-assisted fingerprinting of Pseudomonas aeruginosa. In this method, DNA is digested with SalI, and bands with molecular sizes of >/=9.7 kb are visually scored after electrophoresis on agarose gels. Pattern scores are entered into a Microsoft Excel database. In scoring, the number of bands within each of a set of molecular size ranges is scored, rather than the absolute molecular size of each band, substantially enhancing the speed and reproducibility of the method, while eliminating the need for using expensive gel scanning equipment and software. Pattern scores are used to generate matrices of genetic distance values, which can be visualized in neighbor-joining trees. The method reliably distinguishes two epidemiologically unrelated isolates in 99.3% of all comparisons. The genetic relationships between isolates observed with the method were consistent with those obtained by analysis of two P. aeruginosa genes, indicating that it provides valid estimates of genetic divergence between isolates. Using the method, respiratory tract isolates from cystic fibrosis patients in Green Lane Hospital in Auckland, New Zealand, were shown to be genetically less diverse than epidemiologically unrelated isolates from other patients. This finding was not due to the existence of clusters of related strains specialized toward colonization of the respiratory tract and thus was indicative of transmission between patients. Analysis of multiple isolates from individual cystic fibrosis patients suggested that up to five separate clusters of genetically related strains may simultaneously be present in a patient. The method described should significantly enhance our ability to investigate the epidemiology of P. aeruginosa.

Bacterial Outer Membrane Proteins↗
PubMed2000

A comparison of seven tests for serological diagnosis of tuberculosis.

Seven serological tests, two immunochromatographic tests, ICT Tuberculosis and RAPID TEST TB, and five enzyme-linked immunosorbent assays, TUBERCULOSIS IgA EIA, PATHOZYME-TB complex, PATHOZYME-MYCO IgG, PATHOZYME-MYCO IgA, and PATHOZYME-MYCO IgM, were evaluated simultaneously with 298 serum samples from three groups of individuals: 44 patients with active tuberculosis, 204 controls who had undergone the Mantoux test (89 Mantoux test-positive and 115 Mantoux test-negative controls), and 50 anonymous controls. The sensitivities of the tests with sera from patients with active tuberculosis were poor to modest, ranging from 16 to 57%. All the tests performed equally with sera from subgroups of those with active tuberculosis, those with pulmonary (33 patients) versus extrapulmonary (11 patients) disease, and those who were smear positive (24 patients) versus smear negative (12 patients) (P > 0.05). The specificities of the tests ranged from 80 to 97% with sera from the Mantoux test controls and 62 to 100% with sera from the anonymous controls. The TUBERCULOSIS IgA EIA had the highest sensitivity (57%) with sera from patients with active tuberculosis, with a high specificity of 93% with sera from the Mantoux test controls, but a very poor specificity of 62% with sera from the anonymous controls. Overall, ICT Tuberculosis followed by PATHOZYME-MYCO IgG had the best performance characteristics, with sensitivities of 41 and 55%, respectively, with sera from patients with active tuberculosis and specificities of 96 and 89%, respectively, with sera from the Mantoux test controls and 88 and 90%, respectively, with sera from the anonymous controls. By combining all the test results, a maximum sensitivity of 84% was obtained, with reciprocal drops in specificities to 55 and 42% for the Mantoux test controls and anonymous controls, respectively. The best combination was that of ICT Tuberculosis and PATHOZYME-MYCO IgG, with a sensitivity of 66% and a specificity of 86% for the Mantoux test controls and a sensitivity and specificity of 78% for the anonymous controls. While a negative result by any one of these tests would be useful in helping to exclude disease in a population with a low prevalence of tuberculosis, a positive result may aid in clinical decision making when applied to symptomatic patients being evaluated for active tuberculosis.

Adolescent↗
PubMed2000

The oral health of South Asian five-year-old children in deprived areas of Dudley compared with White children of equal deprivation and fluoridation status.

OBJECTIVE: To investigate the oral health of five-year-old children from South Asian ethnic groups and compare this with White children of equal deprivation and fluoridation status. DESIGN: An epidemiological survey of five-year-old children in Dudley was carried out as part of the 1996 BASCD co-ordinated programme but with the collection of additional variables (ethnic classification and postcode of residence). CLINICAL SETTING: The examinations were carried out in schools in Dudley, England. PARTICIPANTS: Five hundred and fifty-four five-year-old children living in neighbourhoods with an ACORN code F (striving) and attending schools in the fluoridated part of Dudley. MAIN OUTCOME MEASURES: Disease levels were measured using the dmft index. Caries was diagnosed at the caries into dentine (d3) threshold using a visual method without radiography or fibre-optic transillumination. RESULTS: The prevalence of dental caries, particularly untreated caries, was higher in South Asian children. There was no difference in the intensity or pattern of disease between the two groups when comparing those children with disease experience. CONCLUSIONS: Dental caries experience in young children continues to be associated with ethnicity once the data are controlled for deprivation and fluoridation status.

Bangladesh↗
PubMed1999

Phosphatidylinositol 4-phosphate 5-kinase alpha is a downstream effector of the small G protein ARF6 in membrane ruffle formation.

Synthesis of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2], a signaling phospholipid, is primarily carried out by phosphatidylinositol 4-phosphate 5-kinase [PI(4)P5K], which has been reported to be regulated by RhoA and Rac1. Unexpectedly, we find that the GTPgammaS-dependent activator of PI(4)P5Kalpha is the small G protein ADP-ribosylation factor (ARF) and that the activation strictly requires phosphatidic acid, the product of phospholipase D (PLD). In vivo, ARF6, but not ARF1 or ARF5, spatially coincides with PI(4)P5Kalpha. This colocalization occurs in ruffling membranes formed upon AIF4 and EGF stimulation and is blocked by dominant-negative ARF6. PLD2 similarly translocates to the ruffles, as does the PH domain of phospholipase Cdelta1, indicating locally elevated PI(4,5)P2. Thus, PI(4)P5Kalpha is a downstream effector of ARF6 and when ARF6 is activated by agonist stimulation, it triggers recruitment of a diverse but interactive set of signaling molecules into sites of active cytoskeletal and membrane rearrangement.

ADP-Ribosylation Factor 1↗