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Biomedical subjects

M M Ferguson

Publications and source records attributed to M M Ferguson.

At least 37 records · Page 2Linked to original sources
PubMed2001

Concepts for the prophylaxis of infective endocarditis in dentistry.

Oral commensal microorganisms are commonly associated with the pathogenesis of infective endocarditis. Despite modern antimicrobial and surgical treatment, infective endocarditis continues to cause substantial morbidity and mortality. Although dentistry is no longer considered a major risk factor for infective endocarditis, it is current standard for practice that dental procedures likely to produce significant bacteraemia in patients who are susceptible to this disease be prophylactically covered with an antimicrobial agent. The concepts of antimicrobial prophylaxis prior to invasive dental procedures are outlined in this review, with particular reference to the latest recommendations of the Australian Dental Association.

Anti-Bacterial Agents↗
PubMed2000

Effect of nonsense mutations on PTEN mRNA stability.

Cowden disease is an autosomal dominant disorder associated with an elevated risk of breast, thyroid and skin cancers, in which germline mutations of a tumour suppressor gene (PTEN) have been identified. PTEN has a dual-specificity tyrosine phosphatase domain thought to be essential for tumour suppression. Previous genotype/phenotype correlations have identified several potential associations, for example that truncating mutations result in increased breast cancer risk. Such associations are useful in evaluating the phenotypic functions of PTEN sub-domains. However, genotype/phenotype correlations are likely to be complicated by nonsense mediated mRNA degradation. We report here that three out of four mutations do not significantly affect PTEN transcript stability. Furthermore, we show that manual sequencing methods are better than current dye-based sequencing technologies for detecting heterozygous mutations in PTEN transcripts.

DNA Mutational Analysis↗
PubMed2000

A microsatellite linkage map of rainbow trout (Oncorhynchus mykiss) characterized by large sex-specific differences in recombination rates.

We constructed a genetic linkage map for a tetraploid derivative species, the rainbow trout (Oncorhynchus mykiss), using 191 microsatellite, 3 RAPD, 7 ESMP, and 7 allozyme markers in three backcross families. The linkage map consists of 29 linkage groups with potential arm displacements in the female map due to male-specific pseudolinkage arrangements. Synteny of duplicated microsatellite markers was used to identify and confirm some previously reported pseudolinkage arrangements based upon allozyme markers. Fifteen centromeric regions (20 chromosome arms) were identified with a half-tetrad analysis using gynogenetic diploids. Female map length is approximately 10 M, but this is a large underestimate as many genotyped segments remain unassigned at a LOD threshold of 3.0. Extreme differences in female:male map distances were observed (ratio F:M, 3.25:1). Females had much lower recombination rates (0.14:1) in telomeric regions than males, while recombination rates were much higher in females within regions proximal to the centromere (F:M, 10:1). Quadrivalent formations that appear almost exclusively in males are postulated to account for the observed differences.

Animals↗
PubMed1999

A pilot study of the disposition of pilocarpine in plasma, saliva and urine after a single oral dose.

Concentrations of pilocarpine in plasma, saliva and urine from three healthy male volunteers were measured using a fluorescence derivatisation method, following administration of a single 10 mg oral dose. Pharmacokinetic parameter values were estimated from concentration-time profiles. Linear correlations between plasma and saliva pilocarpine concentrations (r2=0.945, n=10, p<0.001; r2=0.954, n=12, p<0.001) and plasma concentrations and salivation rate (r2=0. 863, n=12, p<0.001; r2=0.862, n=15, p<0.001) were established. Pilocarpine and an unidentified metabolite, respectively 20.3% and 34.7% of the oral dose, were excreted into urine.

Adult↗
PubMed1998

Wine tasting and dental erosion. Case report.

A case of widespread dental erosion is reported in an individual who had worked in the wine industry for ten years. This occupation involved daily tasting of at least 20 wines, but often more. The erosion manifested as dental sensitivity with there being cervical erosion, occlusal pitting, and loss of enamel around restorations. The effect of immersing unerupted human teeth in white wine (pH 3.3) was examined with the scanning electron microscope, where marked surface changes had occurred after 24 hours of exposure.

Adult↗
PubMed1998

Identification of a novel PTEN mutation (L139X) in a patient with Cowden disease and Sjögren's syndrome.

Cowden disease is an autosomal dominant disorder associated with an increased risk of breast, thyroid, and skin cancer in which germline mutations in a candidate tumour suppressor gene (PTEN) have been identified previously. Sjögren's syndrome is a chronic inflammatory and autoimmune disorder of exocrine glands for which the genetic basis is unknown. This report describes a novel PTEN mutation (L139X) in a patient with Cowden disease and Sjögren's syndrome. This observation raises the possibility of a link between mutations in the PTEN gene and Sjögren's syndrome.

Adult↗
PubMed1997

Bifid mandibular condyle.

The bifid mandibular condyle remains a relatively uncommon entity although the number of reports continues to accumulate, usually as incidental radiographic findings. It would appear that it may arise in at least two different ways, traumatically and developmentally. A case is presented of a unilateral bifid condyle in a young female. From the radiological examination, including CT, the left condyle was seen to be divided medio-laterally by a groove located on the anterior aspect. A history of trauma was inconclusive and no link was apparent with respect to the patient's medical history. Since the patient's original complaint improved with the management of her oral symptoms and the provision of new dentures, no other treatment of the joint was indicated. The case is discussed in connection with the relevant literature.

Adult↗
PubMed1997

Matriarchal genetic population structure of North American beluga whales Delphinapterus leucas (Cetacea: Monodontidae).

The North American beluga whale Delphinapterus leucas population has been divided into a number of putative geographical stocks based upon migration routes and areas of summer concentration. Nucleotide sequences of the mitochondrial DNA (mtDNA) control region were used to assess whether these geographical stocks are genetically distinct. Beluga whale samples from 25 sites were collected primarily from aboriginal subsistence hunts across North America from 1984 to 1994. Thirty-nine mtDNA haplotypes were identified in 628 beluga samples. No differences were found in the distribution of haplotypes between male and female beluga whales at any sampling site. These haplotypes segregated into two distinct assemblages in both a haplotype network and a neighbour-joining tree. The haplotype assemblages and a geographically disjunct distribution that suggests postglacial recolonization of the North American Arctic from two different refugia. An analysis of molecular variance based on haplotype relationships and frequency indicated genetic heterogeneity among beluga whale summering groups (P < or = 0.001). Sequence divergence estimates between sampling sites also indicated geographical differentiation, particularly between samples taken at east Hudson Bay or St Lawrence River and the western or central Arctic. The results of this study show a high degree of philopatry to specific summering areas by this highly mobile animal.

Animals↗
PubMed1996

Serum pilocarpine esterase activity and response to oral pilocarpine.

Pilocarpine is used orally to treat xerostomia but patients vary widely in their response and ability to tolerate this drug. To elucidate the potential pharmacokinetic contribution of serum to this variability, the enzymatic hydrolysis of pilocarpine in human serum in vitro was investigated using a stability indicating HPLC assay. The reaction at 37 degrees C follows Michaelis-Menten kinetics (K(m) = 2.78 +/- 0.48 mmol/liter, Vmax = 79 +/- 13 nmol min-1 ml 1; n = 5) and produces pilocarpic acid as the only detectable product. The distribution of pilocarpine esterase activity in a group of healthy young adults at age 21 (n = 163; 87 males, 76 females) was examined by incubating serum samples with pilocarpine (10 mmol/ liter) at 37 degrees C for 60 min. The distribution was positively skewed and ranged from 4 to 132 nmol min-1 ml-1 with a mean value of 55 +/- 23 nmol min-1 ml 1. The means for males and females were not significantly different. Similar measurements in xerostomia patients undergoing treatment with oral pilocarpine showed that those with higher serum esterase activity tolerated pilocarpine well and tended to require higher doses for relief of xerostomia, whereas those with low activity were sensitive to the adverse effects of the drug and were adequately treated with a lower dose. The results suggest that at least some of the variability in response to oral pilocarpine is due to differences in serum pharmacokinetics.

Adult↗
PubMed1996

Superficial copper staining of the teeth in a brass foundry worker.

A 21 year-old man developed green surface staining of the cervical margins of his teeth 10 months after starting work in a brass foundry. During this time he was exposed intermittently to brass fumes which contained approximately 75% copper and 2-5% lead. The staining of his teeth was attributed to the absence of respiratory protection in the knock-out process and was accompanied by a rising blood lead concentration. Staining of the teeth by copper was described early this century but seems to have been neglected in the recent literature and texts on occupational medicine. We suggest that in brass foundry workers it is a warning of failure to control fume or dust exposure with the attendant risk of lead toxicity.

Adult↗
PubMed1996

Molecular genetic examination of the polymorphic Arctic charr Salvelinus alpinus of Thingvallavatn, Iceland.

Thingvallavatn, Iceland contains two sympatric morphotypes (benthic and limnetic) of Arctic charr Salvelinus alpinus. Each morphotype is composed of two morphs and these differ markedly in ecology, behaviour and life history. We used molecular genetic approaches to test whether (i) genetic heterogeneity exists among morphs and (ii) if morphs arose in allopatry and came into secondary contact or arose sympatrically within the lake through genetic segregation and/or phenotypic plasticity. Direct sequencing of 275 bp of the mitochondrial DNA (mtDNA) control region, mtDNA restriction fragment length polymorphisms and single locus minisatellite analyses detected insufficient variation to test our hypotheses. Analysis of multilocus minisatellite band sharing detected no significant differences between morphs within the same morphotype. However, significant differences among morphs belonging to different morphotypes suggest some genetic heterogeneity in Thingvallavatn charr. Limnetic charr from Thingvallavatn were more similar to sympatric benthic charr than to allopatric limnetics from two other Icelandic lakes. This suggests that the Thingvallavatn morphs arose sympatrically within the lake rather than in allopatry followed by secondary contact.

Animals↗
PubMed1996

The use of low-tack chewing gum for individuals wearing orthodontic appliances.

A clinical study was carried out to determine the acceptability of a sugar-free, low-tack chewing gum by orthodontic patients undergoing fixed appliance treatment. Twenty-five orthodontic and 25 non-orthodontic control subjects were questioned on their preference between regular-tack and low-tack chewing gum. The orthodontic subjects showed a strong preference for the low-tack gum compared with the regular-tack gum. It was concluded that low-tack, sugar-free chewing gum can be used by orthodontic patients to increase saliva flow, with the potential to promote remineralization and help reduce white spot lesion formation related to fixed orthodontic appliances. This gum should also be of value in patients being treated for xerostomia who are wearing a partial denture.

Adhesiveness↗
PubMed1996

Enamel erosion related to winemaking.

Enamel erosion is a recognized problem in those ingesting large quantities of fruit juice. While discomfort of the teeth is acknowledged to be a problem for those people tasting wines regularly, the information is anecdotal. A case is presented of a winemaker who has generalized erosion of the teeth, the onset of which is related to his occupation.

Adult↗