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Biomedical subjects

M I Sinclair

Publications and source records attributed to M I Sinclair.

At least 19 recordsLinked to original sources
PubMed2001

Changes in the incidence of gastroenteritis and the implementation of public water treatment.

There are few data available on the incidence of endemic waterborne disease in the developed world. This study aims to determine if there was a measurable decline in gastroenteritis related faecal specimens following the introduction of water treatment. The rate of faecal specimens for gastroenteritis was obtained for 17 communities one year before and after the introduction of water treatment in two states of Australia between 1992 and 1996. Of these 17 systems, 10 had filtration added to existing disinfection, while seven had both disinfection and filtration or disinfection alone added to no existing treatment. The rate of faecal sampling varied from a reduction of 55% to an increase of 198%. Large changes in water quality parameters occurred following treatment but there was no significant correlation between these changes and changes in the rate of faecal specimens. In this study there was no consistent change in gastrointestinal related faecal specimens despite marked changes in water quality. This suggests that the reduction in endemic gastrointestinal disease as a result of the introduction of water treatment was small as a percentage of all gastroenteritis. However, water treatment remains essential to protecting public health.

Australia↗
PubMed2001

Water fluoridation, osteoporosis, fractures--recent developments.

BACKGROUND: Optimal (1ppm) water fluoridation is seen as the most socially equitable way to prevent dental caries, however concerns about the safety of fluoridation are periodically raised. METHODS: Research on effects on bone published since the 1991 National Health and Medical Research Council report on water fluoridation was reviewed. RESULTS: Thirty-three studies were identified. Adverse effects in animal feeding studies were only seen at doses much greater than those currently used in artificial water fluoridation. The majority of animal studies showed no effect or a beneficial effect of low fluoride doses. The results of ecological studies were conflicting. One of the two cohort studies showed an increase in fracture incidence at fluoride levels four times greater than optimal water fluoridation and the other showed no effect after 20 years' optimal fluoridation. The cross-sectional studies showed a favourable effect on bone mineral density. The clinical trials predominantly showed increased bone density in several sites associated with fluoride treatment of 9-22.6mg fluoride per day for one-four years. CONCLUSION: These studies provide a substantial body of evidence that fluoride at up to 1ppm does not have an adverse effect on bone strength, bone mineral density or fracture incidence.

Adult↗
PubMed2001

Methods used to maintain a high level of participant involvement in a clinical trial.

OBJECTIVES: To describe the strategies adopted to maintain high level participation throughout a community based clinical trial, and the reasons given by participants for why they participated in the study. DESIGN: Observational study. SETTING: Community based clinical trial in Melbourne, Australia that ran for 68 weeks and involved 2811 community based individuals from 600 families. A high level of commitment was required of the families; each participant completed a Health Diary each week of the 68 week study, as well as answering numerous other questionnaires, and providing faecal and blood samples. MAIN RESULTS: Only 41 of the 600 families withdrew from the study; the majority of these families withdrew because they sold their home and moved from the study area. The completion rate of Health Diaries averaged 90.7% over the 68 weeks of data collection. Of the 559 families who completed the study, 524 (93.7%) completed the Participation Questionnaire. The statement that received the highest rating for why families enrolled in the study was they thought the study was researching an important community issue. The statements that received the highest ratings for why families continued to participate in the study was the family being kept well informed about the study's progress and that the study was well run. CONCLUSIONS: The low numbers of withdrawals and the high level of participation throughout the study suggests the strategies of (a) having a non-aggressive recruitment method, (b) maintaining regular contact with the participants and (c) ensuring participants were kept well informed of the study's progress and constantly encouraged to continue participation were successful. The results also suggest people involve themselves in research because they perceive it to be of value to the community, not simply for personal gain. They indicated that they maintained their participation because it was a well run study and they were kept well informed throughout the study.

Adolescent↗
PubMed2001

A randomized, blinded, controlled trial investigating the gastrointestinal health effects of drinking water quality.

A double-blinded, randomized, controlled trial was carried out in in Melbourne, Australia, to determine the contribution of drinking water to gastroenteritis. Melbourne is one of the few major cities in the world that draws drinking water from a protected forest catchment with minimal water treatment (chlorination only). Six hundred families were randomly allocated to receive either real or sham water treatment units (WTUs) installed in their kitchen. Real units were designed to remove viruses, bacteria, and protozoa. Study participants completed a weekly health diary reporting gastrointestinal symptoms during the 68-week observation period. There were 2,669 cases of highly credible gastroenteritis (HCG) during the study (0.80 cases/person/year). The ratio of HCG episode rates for the real WTU group compared to the sham WTU group was 0.99 (95% confidence interval, 0.85-1.15, p = 0.85). We collected 795 fecal specimens from participants with gastroenteritis, and pathogens were not more significantly common in the sham WTU group. We found no evidence of waterborne disease in Melbourne. The application of this methodology to other water supplies will provide a better understanding of the relationship between human health and water quality.

Adult↗
PubMed2000

Prevalence of enteric pathogens among community based asymptomatic individuals.

BACKGROUND AND AIMS: The objective of this study was to describe the prevalence of pathogenic microorganisms in asymptomatic individuals in a community study in Melbourne, Australia. METHODS: The study population was a subset of 2803 individuals participating in the Water Quality Study; a community based randomized trial. Faecal specimens (1091) were collected over a 3-month period from asymptomatic individuals. Specimens were tested for a range of bacteria including Salmonella, Shigella and Campylobacter species. Rotavirus and adenovirus were detected using a Rota-Adeno latex kit, and protozoa were detected using a permanent stain (modified iron-haemotoxylin). RESULTS: Twenty-eight known pathogens were identified from the 1091 faecal specimens, a total carriage rate of 2.6%. Giardia species were present in 18 specimens (1.6%), Salmonella in four (0.4%), Campylobacter in one (0.1%), Cryptosporidium in four (0.4%) and adenovirus in one (0.1%). Blastocystis hominis was found in 65 specimens. The median age of those without a pathogen was 12.5 years compared with 6.6 years for those with a pathogen (P=0.02). CONCLUSIONS: Except for Giardia, pathogens were rarely found in asymptomatic individuals in the community. The prevalence of pathogens was higher in children than adults.

Adolescent↗
PubMed2000

An outbreak of cryptosporidiosis in an urban swimming pool: why are such outbreaks difficult to detect?

OBJECTIVE: To describe an outbreak of Cryptosporidium gastroenteritis in a swimming pool in Melbourne in early 1998 that was not detected through routine surveillance, and discuss difficulties in identifying such outbreaks. METHODS: The Water Quality Study (WQS) was a large community-based study of gastroenteritis. Following suspicion of an outbreak of cryptosporidiosis within the study group, due to pool "X", a nested case control study was performed. Each case of Cryptosporidium gastroenteritis was matched with six controls and data from weekly Health Diaries from the WQS were reviewed. The Department of Human Services also instigated active surveillance among patrons at pool "X" using a systematic sample of 50 people from the pool's swim-school enrollment list. RESULTS: There were seven cases of Cryptosporidium gastroenteritis in the case control study. Five cases and eight controls swam at pool "X" during the outbreak period. The adjusted odds of developing cryptosporidial diarrhoea if an individual swam at pool "X" was 34.5 (CI 2.3-2548). DHS identified another 11 laboratory confirmed cases associated with pool "X" as well as cases not linked to pool "X". 125 cases were identified throughout Melbourne with the suspected involvement of seven swimming pools. CONCLUSIONS: Despite a high odds ratio of developing cryptosporidiosis this outbreak was not detected by routine surveillance methods. Current outbreak detection methods lack sensitivity, specificity or timeliness. IMPLICATIONS: Improved surveillance systems are required if outbreaks of gastroenteritis are to be detected early so an intervention can be instigated to reduce the amount of subsequent illness.

Animals↗
PubMed1999

Determinants of antibodies to Cryptosporidium infection among gay and bisexual men with HIV infection.

A cross-sectional serosurvey for markers of prior Cryptosporidium infection was conducted among homosexual or bisexual males infected with human immunodeficiency virus (HIV); of 262 individuals approached, 236 (90%) agreed to participate. Serological response to two Cryptosporidium antigens was measured using a Western blot assay. The intensity or detection of serological responses to two Cryptosporidium antigens was not associated with CD4 cell counts or tap water consumption. A number of sexual practices were related to increased serological response for only the 27-kDa marker, including having had sex within the past 2 years, having anal sex and having had a larger number of sex partners during the past 2 years. Attending a spa or sauna was related to serological response to both the 27-kDa and 17-kDa markers. Based on these results, activities related to sexual activity appear to be a significant risk factors for prior Cryptosporidium infection.

AIDS-Related Opportunistic Infections↗
PubMed1993

Investigation of hematuria at a printing company.

An investigation was undertaken at a printing company into an apparently high prevalence of trace dipstick hematuria discovered during routine medical examinations. In both the printing employees (n = 225) and a control group (n = 118) from other industries, the prevalence of hematuria exceeded that described in most previous reports (31% and 25%, respectively, using the criterion of > 12 glomerular red cells or > 2 nonglomerular red cells/microliter of urine). No focus of abnormality was identified within the printing plant and no association was identified between reported exposure to potentially toxic substances and the degree of hematuria. An occupational hygiene inspection and medical follow-up of selected workers did not reveal any significant abnormalities. The limitations of available information concerning "normal" urinalysis results suggests that hematuria may not be a useful test for the screening of occupational groups at risk of bladder cancer.

Adolescent↗
PubMed1991

Chromosomal insertion of TOL transposons in Pseudomonas aeruginosa PAO.

Insertions of the TOL plasmid transposons Tn4651 and Tn4653 into the Pseudomonas aeruginosa PAO chromosome were isolated by a temperature selection technique. The locations and orientations of 16 insertions were determined by pulsed field gel electrophoresis and Southern hybridization with genomic and TOL DNA probes. All insertions occurred within a 334 kb region of the chromosome (representing less than 6% of the genome) with nine of the inserts clustered within a 10 kb area. Each transposon was able to insert in either orientation. An internal duplication of the 39 kb excisable region of pWW0 was seen in two independent insertions.

Chromosome Mapping↗
PubMed1986

Chromosomal location of TOL plasmid DNA in Pseudomonas putida.

The soil isolate Pseudomonas putida MW1000 can grow on toluene and other hydrocarbons; in this respect it is similar to strains of Pseudomonas which carry the TOL plasmid. By conjugation experiments, the genes conferring these growth abilities have been shown to be located on the bacterial chromosome, linked to vil and catB. A 56-kilobase segment of the bacterial chromosome of MW strains carrying the TOL genes can transpose to the IncP-1 plasmid R18-18. Physical analysis of these TOL R18-18 hybrids has shown that the TOL segment is almost identical to the same region found in the TOL plasmid pWW0.

Chromosome Mapping↗
PubMed1982

A chromosomally located transposon in Pseudomonas aeruginosa.

A new transposon, Tn2521, coding for carbenicillin, streptomycin, spectinomycin, and sulfanilamide resistance, has been identified in Pseudomonas aeruginosa. The transposon occurs naturally in the chromosome of clinical strains of P. aeruginosa isolated in geographically separated hospitals. This has been demonstrated by its transductional linkage to the pur-136 marker and also by Southern hybridization. Tn2521 is 6.8 kilobases, can transpose from the chromosome to both IncP-1 and IncP-2 plasmid genomes, and has a pattern of restriction endonuclease sites unlike that of any previously described transposon. The carbenicillin resistance carried by Tn2521 is due to the PSE-4 type of beta-lactamase.

Anti-Bacterial Agents↗