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Biomedical subjects

V Burke

Publications and source records attributed to V Burke.

At least 109 records · Page 6Linked to original sources
PubMed1992

Epidemiology and microbiology of diarrhoea in young Aboriginal children in the Kimberley region of Western Australia.

Infectious diarrhoea is common in young Australian Aborigines and is one of the main causes for their unsatisfactory health standards with consequent widespread failure to thrive and undernutrition. Most published reports relate to patients in hospital or to hospital admission statistics and give little indication of the extent or severity of diarrhoeal disease in children in Aboriginal communities. The present investigation involved more than 100 Aboriginal children up to 5 years of age living in remote communities in the tropical north of Western Australia who were studied prospectively over a 12-month period.

Bacterial Infections↗
PubMed1992

Virulence factors of enteric Escherichia coli in young Aboriginal children in north-west Australia.

Enterotoxigenic Escherichia coli (ETEC) were the most frequently identified enteric pathogens associated with diarrhoea in 0-5 year old Aboriginal children in tropical north-west Australia with an incidence similar to those from other tropical regions. Heat-stable toxin-producing (ST+) strains were associated with diarrhoea throughout the year but heat-labile toxin-producing (LT+) strains were more important in the monsoonal summer season. ST+ strains were commonest in children with diarrhoea between 6 and 18 months of age while LT+ strains were associated with diarrhoea in children aged 18-24 months. Vero-toxigenic E. coli (VTEC) which produced VT1, but not VT2, and enteroadherent (EAF+) E. coli were significant causes of diarrhoea, mainly in children below 18 months but without a seasonal pattern.

Australia↗
PubMed1992

Maternal and environmental factors associated with infections and undernutrition in young Australian aboriginal children.

Forty-eight Aboriginal infants in remote communities in north-west Australia were studied monthly from birth to 2 years. Birthweight and growth were positively associated with maternal health during pregnancy, regular antenatal supervision and lack of drinking alcohol or smoking tobacco as well as with personal and family hygiene. Impaired growth was associated with families which had more expensive consumer goods such as televisions, air conditioners, video cassette recorders and cassette tape players. Most children had impaired growth or frank failure to thrive which was associated with high rates of infections, particularly of the respiratory and gastro-intestinal tracts, and high rates of hospitalization.

Adult↗
PubMed1992

Differential effect of aspirin on platelet aggregation in IDDM.

Diabetes mellitus is associated with a high incidence of cardiovascular diseases not directly attributable to hyperlipidemia, smoking, or hypertension, but which in part may be explained by an enhanced tendency to thrombosis due to increased platelet activity. The aim of this study was to evaluate platelet function and compare the effectiveness of the antiplatelet drug aspirin on platelet aggregation in diabetic and nondiabetic subjects. Platelet aggregation and composition were examined in 20 male insulin-dependent diabetes mellitus (IDDM) patients and 20 nondiabetic control subjects matched for age and body mass index. All were normotensive with serum total cholesterol less than 6.5 mM. Although within the clinically acceptable normal range, blood pressure was significantly higher in diabetic patients (130/75 mmHg) than in control subjects (123/70 mmHg) (P less than 0.05). Serum thromboxane B2 and ex vivo aggregation of platelets in response to two doses of the agonists collagen and platelet-activating factor (PAF) were similar to nondiabetic subjects. However, after taking 100 mg/day aspirin for 5 days, platelet aggregation to collagen was reduced by 76% in control subjects compared to 56% in IDDM patients (P less than 0.001). Aspirin treatment also reduced the slope of the aggregation curve and increased the lag time (the period between the addition of collagen and the start of irreversible aggregation) significantly more in control than in diabetic platelets. This difference in platelet aggregation could not be attributed to differences in platelet serotonin or thromboxane A2 secretion, the latter being almost completely suppressed by aspirin in each group. Platelet aggregation to PAF was similar in both groups and was not affected by aspirin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Changes in markers of alcohol intake in man below 'safe' drinking levels.

In a group of 343 working men, only 34 of whom regularly drank more than 60 ml of ethanol per day, logistic regression was used to determine the combination of biomarkers which best discriminated between those who regularly drank less than 30 ml or 30 ml or more of ethanol daily. The index consisted of apolipoprotein A-II, uric acid, gamma-glutamyl transpeptidase and mean corpuscular volume. Even with the relatively low level of alcohol intake reported in these subjects (assessed using a 7-day retrospective alcohol diary), the groups with higher or lower intake of alcohol were separated with a sensitivity of 68%, a specificity of 74% and a positive predictive value of 71%. Systolic blood pressure, adjusted for age and body mass index, was also linearly related to alcohol intake, and when included in the biomarker index improved the proportion correctly classified from 71% to 75%. Using the biomarkers only, 94% of subjects regularly drinking at least 80 ml of ethanol equivalent per day and 100% of the non-drinkers were correctly classified.

Adult↗
PubMed1992

Postural fall in blood pressure in the elderly in relation to drug treatment and other lifestyle factors.

In a study of 843 independent-living men and women aged between 60 and 87 in Perth, Western Australia, stepwise multiple regression, after correction for initial levels of systolic blood pressure, showed that postural fall in systolic blood pressure was positively related to alcohol intake of more than 20 ml/day, the use of sleeping tablets and higher levels of anxiety on the Spielberger state-trait scale, and negatively related to body mass index. Postural fall in blood pressure was not significantly related to treatment for hypertension, age, sex, patterns of usual physical activity, tea or coffee drinking, or the diagnosis of diabetes mellitus. This analysis is the first to examine the relationship between lifestyle factors and the magnitude of the fall in systolic blood pressure on standing after adjustment for the association between the change in a variable and its initial level. Our analysis suggests the need for further study of the possible role of lifestyle factors such as the use of sleeping tablets and alcohol in postural hypotension in the elderly.

Aged↗
PubMed1991

Effects of alcohol intake on plasma fatty acids assessed independently of diet and smoking habits.

1. This study was designed to determine prospectively whether changing alcohol consumption influenced the proportion of plasma linoleic acid independently of diet or smoking habits, and to evaluate changes in the plasma linoleic acid concentration as a potential marker of changes in alcohol consumption. 2. Fasting plasma fatty acid profiles were investigated in 72 male drinkers who were randomly assigned to drink low-alcohol beer or to maintain their usual drinking habits for a period of 4 weeks. 3. At entry to the study, a higher alcohol intake was associated with lower proportions of plasma linoleic acid, arachidonic acid and dihomolinolenic acid and higher proportions of plasma palmitoleic acid, independently of changes in body mass index. Smoking habits were unchanged and there were no major changes in diet during the period of the intervention. 4. Because the plasma palmitoleic acid concentration has been suggested as a possible marker of 'at risk' drinking, we investigated plasma fatty acid concentrations as indicators of alcohol intake. The plasma palmitoleic acid concentration was not a useful discriminator. Indices determined using logistic regression and combining plasma apolipoprotein A-II and linoleic acid concentrations gave better discrimination than either variable alone.

Adult↗
PubMed1991

Cytotoxic effects of children's faeces: relation to diarrhoea due to Clostridium difficile and other enteric pathogens.

Cytotoxicity of faecal extracts was demonstrated in 47 of 88 children (54%) referred for microbiological investigation of stools. Cytotoxic Clostridium difficile and vertotoxigenic Escherichia coli (VTEC) were the pathogens identified most commonly but cytotoxicity was also found in association with Campylobacter jejuni, Salmonella spp, Shigella sonnei, Giardia lamblia, rotavirus, adenovirus and poliovirus type 1 which had been acquired by oral immunization. In two patients, one of whom had cystic fibrosis, cytotoxicity of faecal extracts was associated with isolation of Pseudomonas aeruginosa. In five of 13 patients with diarrhoea and cytotoxic C. difficile, other pathogens were also present, in agreement with the view that C. difficile are more readily recovered when the intestinal flora have been altered by colonization with other micro-organisms. There was no correlation between previous treatment with antibiotics and isolation of C. difficile. Cytotoxicity neutralized by antitoxin, usually to C. sordellii, is used to detect cytotoxic C. difficile. We suggest that cytotoxicity not neutralized in this way should be an indication for further investigation of stools for the presence of other pathogens such as VTEC or viruses.

Adolescent↗
PubMed1991

Influence of soluble haemagglutinins on adherence of Helicobacter pylori to HEp-2 cells.

In a study of six laboratory strains of Helicobacter pylori, two different modes of bacterial adherence to HEp-2 cells were found. Electronmicroscopy revealed that strains known to possess soluble haemagglutinin adhered intimately to the cell surfaces, with cupping of the plasma membrane and coalescence of glycocalyces at sites of attachment. Strains of H. pylori without soluble haemagglutinin also attached, but did not induce membrane cupping or show glycocalyx fusion. Light microscopy did not distinguish between these patterns of adherence. Bacterial attachment was unaffected by pre-treatment of HEp-2 cells with neuraminidase. Exposure of the bacteria to trypsin or to colloidal bismuth subcitrate (CBS) before being added to HEp-2 cells markedly impaired bacterial adherence. This effect of CBS may contribute to the known efficacy of bismuth therapy in patients with H. pylori-related gastritis.

Bacterial Adhesion↗
PubMed1991

Longitudinal studies of virulence factors of Pseudomonas aeruginosa in cystic fibrosis.

Among 111 strains of Pseudomonas aeruginosa from 49 children with cystic fibrosis, duration of colonization correlated with bacterial phenotype. We confirmed that P. aeruginosa from chronically colonized patients tended to be less motile, produce lower levels of protease and elastase, to be more sensitive to normal serum and to be polyagglutinating or untypable with standard antisera. We also showed that phospholipase and heat-stable hemolysin, concerned in metabolism of inorganic phosphate, and exotoxin A, were lower in these isolates. In longitudinal studies there was a decrease in virulence properties when isolates from the same patient were compared. No reversion from altered phenotype to 'wild-type' characteristics was found.

ADP Ribose Transferases↗
PubMed1991

Sorbose fermentation in relation to acquisition and maintenance of enterotoxin plasmids in Escherichia coli.

Previous studies have shown that the majority of enterotoxigenic Escherichia coli (ETEC) strains isolated from humans failed to ferment sorbose. In an attempt to demonstrate if this phenomenon was due to enterotoxin (Ent) plasmid instability in sorbose fermenting strains, recipient E. coli strains were used in conjugation experiments with three donor Ent plasmids. No difference in the ability to uptake the Ent plasmid was shown between sorbose fermenting and non-fermenting recipient strains. In addition, no difference was seen in the stability of the Ent plasmids in recipient strains of each biotype. These results suggest that in-vivo selection may play a role in the predominant isolation of non-sorbose fermenting ETEC strains.

Drug Resistance, Microbial↗
PubMed1991

Pyocin typing of Pseudomonas aeruginosa isolates from children with cystic fibrosis.

Pyocin typing and serotyping of 433 strains of Pseudomonas aeruginosa from children with cystic fibrosis (CF) showed that pyocin type 9 was predominant, particularly in association with polyagglutinating serotype. The common pyocin groups, 1, 5 and 10, made up only 20% of these isolates in contrast to reported rates of up to 89% in other studies using non-CF strains. No strains of pyocin type 3 were found. Polyagglutinating strains made up 72% of strains from patients colonized with P. aeruginosa for more than 12 mths. Pyocin type 9 was associated with 93% of polyagglutinating strains. The parallel between pyocin type 9 and polyagglutinating serotype suggests that these may both be characteristics acquired by P. aeruginosa colonizing patients with CF. Because of confounding between duration of colonization and exposure to cross-infection, this study does not allow definition of the role of cross-infection in determining the characteristics of these strains in most patients. In siblings, however, evidence supports a role for cross-infection either between siblings or from a common source. In 6 pairs of siblings studied, each pair had at least 1 pyocin group in common concurrently, either at entry to the study or after an interval of several months. Identical and unusual pyocin groups were recognized in samples obtained on the same day from pairs of siblings. More studies are needed to compare results of pyocin typing with methods such as genome fingerprinting to characterize these strains and determine whether the observed distribution of pyocin groups in CF isolates is related to cross-infection or whether the combination of pyocin type 9 with polyagglutinating serotype is a characteristic of CF strains.

Adolescent↗
PubMed1990

HEp-2 cell adherence and Vero cell cytotoxin production by EPEC strains isolated from children with diarrhoea in New Zealand.

A total of 112 EPEC strains isolated from children with diarrhoea in New Zealand were examined for mannose-resistant HEp-2 cell adherence and production of exotoxins. Enterotoxin production was not detected in any of the strains examined. Verotoxin production was detected in 13 (11.6%) strains and of these 4 were also found to adhere to HEp-2 cells. HEp-2 cell adherence was displayed by a total of 29 (25.8%) strains of which 22 were diffusely adherent. Only 3 (2.7%) strains were shown to belong to the new virulence phenotype, entero-aggregative adherence, when examined in the adherence assay. We identified one strain with the novel characteristic of causing detachment of HEp-2 cells from glass coverslips and are further investigating this possible virulence mechanism. These results suggest that if EPEC strains are to be considered as a cause of diarrhoea, the search for new virulence factors must be extended.

Animals↗
PubMed1990

Soluble and cell-associated haemagglutinins of Helicobacter (Campylobacter) pylori.

Some plate-grown strains of Helicobacter (Campylobacter) pylori that were harvested into phosphate-buffered saline and left for 1 h released soluble haemagglutinins. These caused high-titre agglutination of human and guinea-pig erythrocytes, whereas chicken, sheep and bovine erythrocytes were agglutinated at various titres. Six of 10 strains which had been subcultured repeatedly did not possess soluble haemagglutinins. Slide agglutination of bacterial suspensions demarcated the strains into two groups; Group 1 gave strong agglutination with most types of erythrocyte, Group 2 did not. By microtitration assay, all Group-1 strains but only two Group-2 strains produced a soluble haemagglutinin. Cell-associated haemagglutinins were found by microtitration assay in all strains of H. pylori, but higher titres were found within Group-1 strains. The supernates of broth-grown, shaken cultures also showed the presence of soluble haemagglutinins, with higher titres for recently isolated strains. Pre-treatment of human erythrocytes with neuraminidase from Arthrobacter ureafaciens and Clostridium perfringens abolished haemagglutination by the soluble, but not by the cell-associated haemagglutinin. The soluble haemagglutinin was inhibited by sialoproteins containing predominantly the N-acetylneuraminyl (2-3) galactopyranosyl [NeuAc(2-3)Gal] structure, fetuin, glycophorin and bovine N-acetylneuraminyl-lactose (NeuAc-Lac). Transferrin and human NeuAc-Lac, which contain predominantly the N-acetylneuraminyl (2-6) galactopyranosyl [NeuAc(2-6)Gal] structure were not inhibitory. However, bovine submaxillary mucin (BSM) was strongly inhibitory; it contains several structures with sialic acid linked 2-6 to oligosaccharides. These results suggest that the soluble haemagglutinin recognises a NeuAc(2-3)Gal structure, but has high affinity for another, as yet undetermined, sialic acid-containing structure.

Animals↗
PubMed1990

Serotype and serum sensitivity of Pseudomonas aeruginosa from children with cystic fibrosis: longitudinal studies and typing with monoclonal antibodies.

Pseudomonas aeruginosa isolated from the respiratory tract of children with cystic fibrosis from Perth, Sydney or Brisbane, were serotyped with polyclonal antisera using the International Antigenic Serotyping System. Predominant strains were untypable among isolates from Brisbane (86% of 50 strains) and Sydney (60% of 50 strains) but 64% of the 408 isolates from Perth were polyagglutinating. The frequency distributions of typable strains showed differences from those reported in clinics in the northern hemisphere, but it appears that these local differences do not affect the emergence of strains with defective lipopolysaccharide antigens. Isolates from patients studied longitudinally showed correlation between duration of colonization, appearance of untypable or polyagglutinating strains and sensitivity to normal serum. Mucoid colonies were found more commonly from patients colonized for at least 12 months but, overall, there was no significant association between serotype and mucoid colonial morphology. Commercial monoclonal antibodies did not react with polyagglutinating or untypable strains and gave identical results to the polyvalent typing system with strains classified as typable.

Antibodies, Monoclonal↗
PubMed1990

Cardiovascular Diseases and Alimentary Comparison Study: preliminary analysis of data from Western Australia.

Data from 49 men and 48 women included in the Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study in Perth, Western Australia, were analyzed. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were positively correlated (p less than 0.01) with urine sodium, creatine, taurine, histidine, and 3-methyl histidine but not with calcium, magnesium, or potassium. SBP was related (p less than 0.01) with body mass index (BMI). Urine nitrogen, creatinine, and amino acids correlated (p less than 0.001) with each other and with urine sodium, potassium, calcium, and magnesium. Urine magnesium correlated (p less than 0.001) with urine calcium and potassium; urine calcium was not related significantly to urine sodium or potassium. In backwards multiple regression with data from urine collections, SBP was significantly related only to urine sodium (11.9% of variance explained). If alcohol was included as an independent variable, reducing the number of valid cases because of missing values, both alcohol and urine sodium were significant in regression (19.9% of variance explained). In men, DBP was significantly related to BMI and the ratio of 3-methylhistidine to creatine (23.7% of variance explained). For DBP in women, urine sodium was the only variable needed in regression (58.4% of variance explained). Interpretation must be cautious, because these analyses are based on relatively few cases and on single 24-h urine samples. The data are in keeping with suggestions that obesity, alcohol consumption, a meat diet, and sodium intake are important factors predisposing to elevation of blood pressure.

Blood Pressure↗
PubMed1988

An antibacterial and antiviral powdered soft-drink base.

Soft-drink powdered mixtures have been developed which are bactericidal against a range of enteric bacteria and Staphylococcus aureus and which kill some enteric viruses in vitro. These mixtures could be used to help reduce risks of water-borne diarrhoeal illnesses, and as the basis for oral rehydration solutions, which would resist bacterial contamination after their preparation, to treat patients with diarrhoeal dehydration.

Anti-Bacterial Agents↗