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J McBroom

Publications and source records attributed to J McBroom.

8 recordsLinked to original sources
PubMed2002

Apolipoprotein E epsilon4 and testosterone interact in the risk of Alzheimer's disease in men.

OBJECTIVES: To assess the association between testosterone levels and APOEepsilon4 in cases with AD and controls. METHOD: We included 61 men with definite or probable Alzheimer's disease (AD) and 55 elderly male controls from the Oxford Project to Investigate Memory and Ageing (OPTIMA). Testosterone was measured using a competitive enzyme immunoassay (Bayer). RESULTS: We found that both low serum testosterone and the interaction between testosterone and APOEepsilon4 were associated with AD. Furthermore, testosterone levels were lower in APOEepsilon4-positive controls (mean: 11.3 nmol/L) than in controls without the allele (19.1 nmol/L). CONCLUSIONS: Low testosterone is potentially a modifiable risk factor, which may prove relevant to APOEepsilon4 carriers who are at risk of AD.

Aged↗
PubMed2001

Using meta-analysis to explain the diversity of results in genetic studies of late-onset Alzheimer's disease and to identify high-risk subgroups.

In late-onset Alzheimer's disease, there is a puzzling inconsistency between the findings of case-control studies of most proposed risk genes, except apolipoprotein E epsilon4. This inconsistency may stem from the failure to define the genetic and non-genetic interactions that affect the disease association of each particular susceptibility gene. Such interactions will limit the influence of the gene to a 'relevant subset' of vulnerable people. The relevant subsets for many risk genes will be narrow, compared to that of apolipoprotein E epsilon4. Studies may therefore miss the association or even suggest that a risk gene is protective. In these circumstances, the precise composition of a cohort is critical and defining the relevant subset is crucial. We illustrate how such definition may be achieved through meta-analysis. We take as an example the butyrylcholinesterase K variant, whose association with Alzheimer's disease may now be provisionally defined. This analysis leads to the identification of a potentially high-risk group: over 75 year old male carriers of both apolipoprotein E epsilon4 and butyrylcholinesterase K variant.

Age of Onset↗
PubMed2001

Modelling of endemic carriage of Haemophilus influenzae in Aboriginal infants in Northern Australia.

Aboriginal infants and children in rural communities in Northern Australia have high rates of nasopharyngeal carriage of nonencapsulated Haemophilus influenzae (NCHi), with positive swab rates of 76%. In this population, the acquisition of NCHi from soon after birth is associated with the onset of otitis media and with muco-purulent nasal discharge, while the long-term persistence of NCHi carriage is associated with the acquisition and turnover of large numbers of antigenically diverse strains. Mathematical models have been fitted to data on the acquisition and loss of encapsulated strains of H. influenzae and 43 different strains of NCHi in 10 children followed from early infancy for up to 2 years. Subject to plausible assumptions, the preferred model estimated the mean time to acquisition of a H. influenzae strain to be 7 days after first becoming exposed after birth. For an infant already carrying H. influenzae, each additional strain was acquired after a mean waiting period of 45 days. On average, 1.50 different strains of H. influenzae were detected in four colonies routinely typed from each positive swab, but it was estimated that another 2.55 strains were 'hidden' behind these more frequent strains. With an average of 4.05 strains per carrier, it was estimated that each strain was carried for an average of 137 days, although detected on only 37% of occasions. Thus we have developed mathematical models that provide estimates for duration of colonisation, time to colonisation, and number of colonising strains in a population in which H. influenzae is highly endemic, characterised by sequential and concurrent carriage of multiple strains in each infant.

Algorithms↗
PubMed2001

Persistent ICT malaria P.f/P.v panmalarial and HRP2 antigen reactivity after treatment of Plasmodium falciparum malaria is associated with gametocytemia and results in false-positive diagnoses of Plasmodium vivax in convalescence.

A problem with rapid Plasmodium falciparum-specific antigen histidine-rich protein 2 (HRP2) detection tests for malaria is the persistence of antigen in blood after the disappearance of asexual-stage parasitemia and clinical symptoms, resulting in false-positive (FP) test results following treatment. The ICT P.f/P.v immunochromatographic test detects both HRP2 and a panmalarial antigen (PMA) found in both P. falciparum and Plasmodium vivax. To examine posttreatment antigen persistence with this test and whether persistent sexual-stage forms (gametocytes) are a cause of FP tests after treatment, we compared serial antigen test results with microscopy results from patients symptomatic with P. falciparum malaria in Indonesia for 28 days following treatment with chloroquine (CQ; n = 66), sulfadoxine-pyrimethamine (SP; n = 36), and artesunate plus sulfadoxine-pyrimethamine (ART + SP; n = 15). Persistent FP antigenemia following SP treatment occurred in 29% (HRP2) and 42% (PMA) of the patients on day 7 and in 10% (HRP2) and 23% (PMA) on day 14. The high rates of persistent HRP2 and PMA antigenemia following CQ and SP treatment were strongly associated with the presence of gametocytemia, with the proportion with gametocytes on day 7 posttreatment being significantly greater in those with FP results than in those with true-negative PMA and HRP2 results. Gametocyte frequency on day 14 post-SP treatment was also greater in those with FP PMA results. Following SP treatment, PMA persisted longer than HRP2, giving an FP diagnosis of P. vivax in up to 16% of patients on day 14, with all FP P. vivax diagnoses having gametocytemia. In contrast, PMA was rapidly cleared following ART + SP treatment in association with rapid clearance of gametocytemia. Gametocytes appear to be an important cause of persistent posttreatment panmalarial antigenemia in areas of endemicity and may also contribute in part to persistent HRP2 antigenemia following treatment.

Adult↗
PubMed2000

Endocervical curettage when colposcopic examination is satisfactory and normal.

OBJECTIVE: To estimate the incidence of endocervical dysplasia in women with cervical cytology of atypical squamous cells of undetermined significance (ASCUS) or low-grade squamous intraepithelial lesion (SIL) who have a satisfactory and normal colposcopic examination. METHODS: An electronic colposcopy database was reviewed and women with satisfactory colposcopic examinations and original cervical cytology of ASCUS on two consecutive Papanicolaou smears, ASCUS favor SIL, or low-grade SIL were selected. Exclusion criteria were pregnancy, insufficient endocervical curettage (ECC), or colposcopic examination that showed an abnormality that required cervical biopsy. Subjects also were excluded if they were postmenopausal or had surgical or ablative therapy for cervical dysplasia within the past year. A computerized review of 2517 patient records found 860 that met the search criteria. A manual review of those records using the exclusion criteria isolated a study group of 159 women. RESULTS: Four of 159 subjects (2.5%, 95% confidence interval [CI] 0.69, 6.3) had dysplastic cells in endocervical curettings. In these four, the ECC specimens had benign endocervical cells and separate fragments of squamous cells with mild dysplasia. In three women, loop electrosurgical excision procedures showed mild dysplasia limited to the transformation zone. The fourth subject was believed to have contamination from an unrecognized ectocervical lesion and was treated conservatively. A repeat ECC found benign endocervical cells. Involvement of the endocervix by dyplasia was excluded in all but one of 159 patients (0.63%, 95% CI 0.02, 3.5). CONCLUSION: Incidence of endocervical dysplasia was extremely low in women with cervical cytology of consecutive ASCUS, ASCUS favor SIL, or low-grade SIL who have a satisfactory and normal colposcopic examination. Our findings suggest that endocervical curettage might be safely avoided in those women.

Cervix Uteri↗
PubMed1999

Crusted scabies: A molecular analysis of Sarcoptes scabiei variety hominis populations from patients with repeated infestations.

Crusted scabies is a severe debilitating disease due to hyperinfestation with the ectoparasite Sarcoptes scabiei. Treatment protocols include oral ivermectin and topical scabicides. After single-dose ivermectin, there may be early recrudescence, whereas after 3 doses at 14-day intervals, there is an apparent cure. However, such patients often present again after 6-12 months. To clarify the biology of recurrence, we studied genetic markers in sequential populations of S. scabiei mites from treated patients with multiple episodes of crusted scabies. Individual mites were genotyped at hypervariable microsatellite loci by a fluorescence-based polymerase chain reaction. Results indicated that sequential populations of mites were genetically more similar to each other than to mites from other patients. Although the majority of recurrent scabies is probably due to reinfestation from inadequately treated contacts, there was evidence that in very severe crusted scabies, treatment with even 3 doses of ivermectin 14 days apart may be inadequate and relapse may occur.

Alleles↗
PubMed1999

Genetically distinct dog-derived and human-derived Sarcoptes scabiei in scabies-endemic communities in northern Australia.

Overcrowding is a significant factor contributing to endemic infection with Sarcoptes scabiei in human and animal populations. However, since scabies mites from different host species are indistinguishable morphologically, it is unclear whether people can be infected from scabies-infested animals. Molecular fingerprinting was done using three S. scabiei-specific single locus hypervariable microsatellite markers, with a combined total of 70 known alleles. Multilocus analysis of 712 scabies mites from human and dog hosts in Ohio, Panama and Aboriginal communities in northern Australia now shows that genotypes of dog-derived and human-derived scabies cluster by host species rather than by geographic location. Because of the apparent genetic separation between human scabies and dog scabies, control programs for human scabies in endemic areas do not require resources directed against zoonotic infection from dogs.

Alleles↗