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Biomedical subjects

R J Mitchell

Publications and source records attributed to R J Mitchell.

122 records · Page 7Linked to original sources
PubMedDate not supplied

Apolipoprotein AI and CIII gene polymorphisms and their association with lipid levels in Italian, Greek and Anglo-Irish populations of Australia.

PRIMARY OBJECTIVE: The apolipoprotein (apo) AI-CIII-AIV gene cluster on chromosome 11 has been identified as a candidate region for hyperlipidaemia and in particular for hypertriglyceridaemia. Our aim was to detect associations between the apo AI and CIII polymorphisms and the plasma lipids, total cholesterol, triglycerides, high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol in normal, healthy, adults from three ethnic groups of Australia--Italian, Greek and Anglo-Irish, separately by gender. METHODS AND PROCEDURES: The SstI restriction fragment length polymorphisms (RFLP) in the 3' untranslated region of the apo CIII gene and the MspI RFLP in the third intron of the apo AI gene were scored and the lipid concentrations were ascertained using standard methodologies. t-tests were used to compare lipid levels between sexes and between populations, and multivariate ANOVA was used to detect if the two RFLPs had an effect on any of the lipid concentrations. MAIN OUTCOMES AND RESULTS: The two RFLPs exhibit strong linkage disequilibrium in all three populations (p < 0.001). There were some significant differences in allele frequencies among the populations: the minor S2 allele was more frequent in Italians (0.12) than Greeks (0.03) (p = 0.003), and the minor M2 allele was more common in Greeks (0.14) than Anglo-Irish (0.05) (p = 0.026). We found no significant association between either of the RFLPs and any of the lipid concentrations in either sex of all three populations. However, Kruskal-Wallis tests detected associations of borderline significance between apo AI MspI genotypes and triglycerides (p = 0.04) and between apo AI MspI genotypes and cholesterol levels (p = 0.03) in Anglo-Irish females. CONCLUSIONS: Because only two statistically significant associations were detected among a number of comparisons, our data suggest that the apo AI and CIII polymorphisms play only a very limited role in mediating variation in lipid concentrations in these three ethnic groups.

Adult↗
PubMedDate not supplied

An investigation of sequence deletions of amelogenin (AMELY), a Y-chromosome locus commonly used for gender determination.

BACKGROUND: Accurate gender determination is crucial in many scientific disciplines, but especially so in prenatal diagnosis of X-linked diseases and forensic investigations. Today, molecular techniques, especially typing for a length variation in the X-Y homologous amelogenin gene (AMELX and AMELY), are used for gender assignation. This amelogenin test is an integral part of most PCR multiplex kits that are used for DNA profiling, but in 1998 there was a report of two normal males being typed as female with this test. Subsequently, a small number of amelogenin negative (or AMELY null) males have been reported in various populations but little data are available characterising these deletions. AIMS: The study aims to determine the size of the deletion in five AMELY null males by typing DNA samples for markers surrounding this gender-determining locus. The possible relationships among the AMELY null samples are examined through analysis of their deletion size and associated Y-chromosome microsatellite haplotypes. We also attempt to determine the frequency of AMELY negative males in Australia. SUBJECTS AND METHODS: DNA samples from five AMELY null males, from different geographical regions, were made available for this study. The samples were typed for eight sites, all located on the short arm of the Y chromosome, using PCR and gel electrophoresis. Eleven Y-chromosome specific microsatellites were also typed on each sample in order to generate haplotypes for phylogenetic analysis. A questionnaire was sent to all Australian forensic centres requesting information on the frequency of AMELY negative males observed in their laboratories. RESULTS: Two different sized deletions were seen in the five AMELY null samples. One deletion (in two samples) has a size of between 304 and 731 kbp, whereas the other (in three samples) ranges between 712 and 1001 kbp. Y-microsatellite haplotypes indicate that the smaller deletion is probably identical in the two samples, but this is not the case with the larger deletion. The frequency of AMELY negative is rare in Australia, with an overall frequency of 0.02%. CONCLUSION: Comparisons of both deletion size and haplotypes with published data suggest that most AMELY nulls are the result of independent evolutionary events, even in those populations where the frequency is relatively high. Although AMELY null males are extremely rare in most populations, typing an additional gender-determining locus should be considered in forensic investigations where the reference sample is of unknown gender.

Amelogenin↗
PubMedDate not supplied

Genetic variation in Cumbrians.

Regional variation in the genetic constitution of the Cumbrian population is demonstrated in a survey of blood groups, red cell enzymes, and secretor status in a large sample of schoolchildren. In particular, the south and centre appear to be distinct from the remainder of Cumbria, but in different directions. The features of the central Lake District, tending towards gene frequencies observed in Norway, suggest that it may be a region in which the presence of a relict population is still detectable.

Adolescent↗
PubMedDate not supplied

Genetic studies of the population of the Isle of Man.

A sample of the Isle of Man population was tested for the following red cell antigens, serum proteins and red cell enzymes: ABH; MNSs He; Cc CwD Du Ee Ce; K k Kpa Kpb; Lua; P1; Fya Fyb; haptoglobin; transferrin; Ag; acid phosphatase; phosphoglucomutase; adenylate kinase; esterase D; adenosine deaminase and 6-phosphogluconate dehydrogenase. The study comprised 219 blood donors, 338 secondary school children and 116 females attending the only antenatal clinic. The results were studied for intra-island variation and for their their relationship with other Irish Sea Basin populations. The total sample results were compared with data for England, Cumbria, Eire, Northern Ireland, S.W. Scotland and Wales using a genetic distance measure.

ABO Blood-Group System↗
PubMedDate not supplied

Specific cognitive effects of mild iron deficiency and associations with blood polymorphisms in young adults.

This study of 172 university undergraduates examines the relationship of five cognitive tests to iron levels (as measured by a haematofluorometer) and three polymorphic blood markers implicated in either iron metabolism or transport. The markers used were the red cell antigens of the ABO system and the serum proteins transferrin (TF) and haptoglobin (HP). Negative correlations were found between zinc protoporphyrin (ZPP) level and three spatial tests, Reflected Figures (r = -0.23), Form Recognition (r = -0.20) and Block Design (r = -0.18). These findings suggest a possible effect of mild iron decrement upon spatial performance involving spatial visualization and item identification and manipulation. A significant association (P less than 0.05) was also recorded between ZPP level and TF subtype; the rarer the TF subtype, the higher the ZPP level. No support was found for a previously reported association between Block Design performance and HP.

ABO Blood-Group System↗
PubMedDate not supplied

Mating structure, isonymy and social class in late nineteenth century Tasmania.

This study analysed all marriages (N = 4258) registered in the island State of Tasmania during the period 1896-1899 for mating structure, using marital isonymy. We found that irrespective of the geographic size of the subdivisions the random component (Fr) values were similar. This is because there was a high proportion of unique names despite the large population size. Fn values were sensitive to geographic distance only with respect to the 'unrealistically' larger units of analysis. Isonymy is valid over very large distances in Tasmania. Inbreeding values in the study were typical of other mainstream populations, but the nonrandom component was unusually high. Farmer marriages were the major contributors to the high Fn values. One particular region, the Midlands, displayed both a high F (0.0081) and Fn (0.0074) component. The explanation of these values lies in the effects of a rigid socio-economic structure established during colonization.

Female↗
PubMedDate not supplied

Genetic polymorphisms in the white population of Victoria, Australia.

Genetic variation in the rural population of the State of Victoria, Australia, is demonstrated through the analysis of eight genetically independent red cell antigen, red cell enzyme and plasma protein systems in a sample of more than 2000 blood donors. The polymorphisms investigated were ABO, RH, KEL, esterase D (ESD), glyoxalase 1 (GLO1), phosphoglucomutase locus 1 (PGM1), haptoglobin (HP) and the third component of complement (C3). For genetic distance analysis the sample was subdivided into nine regions using the Victorian Government's Statistical Divisions. Considerable regional genetic heterogeneity exists; with the Goulburn and the Central Highlands divisions being the most distinct, not only from the other seven divisions, but also from each other. The pattern of micro-differentiation is complex and cannot be easily explained, but there is evidence of varying levels of systematic evolutionary pressure on the Victorian divisions. The investigation of the proportion born overseas in each division, and their respective countries of origin, did not help in the interpretation of the findings. Overall, rural Victorians exhibited allele frequencies very similar to the populations of both Melbourne, the Victorian capital, and the island State of Tasmania.

Adolescent↗
PubMedDate not supplied

DNA polymorphisms of the cholesteryl ester transfer protein (CETP) gene in Italian and Greek migrants to Australia.

The distribution of two common TaqI restriction fragment length polymorphisms (RFLPs) of the cholesteryl ester transfer protein (CETP) gene were determined in 271 Italian-born and 170 Greek-born migrants to Melbourne, Australia. A much smaller number were examined for the EcoNI RFLP of the same gene. Allele frequencies of the TaqI A RFLP exhibited the least variation in both ethnic groups, and no significant regional heterogeneity in allele or genotype frequencies of either TaqI RFLP was detected for Greece or Italy. There was no difference between Italians and Greeks for the TaqI A polymorphism and the variability at the B RFLP was of borderline significance. Comparisons with other Caucasian populations revealed that allele frequencies of all three CETP RFLPs are remarkably uniform within Caucasians, with the TaqI B polymorphism being the most variable.

Adult↗
PubMedDate not supplied

Phosphoglucomutase 1 (PGM1) subtypes and ESD types in mothers and newborns from the island of Tasmania, Australia.

PGM1 subtypes and ESD phenotypes of 600 mothers and their respective newborn infants residing in the northern part of the island of Tasmania were examined. The allele frequencies of PGM1 in the mothers were 1+ = 0.6525, 1- = 0.1250, 2+ = 0.1758 and 2- = 0.0467, and in the newborns were 1+ = 0.6675, 1- = 0.1275, 2+ = 0.01600 and 2- = 0.0450. Both samples were found to exhibit Hardy-Weinberg equilibrium conditions and there was no significant difference between them. Also, the frequencies of PGM1 alleles were overall similar to frequencies in neighbouring populations on the Australian mainland. The frequency of ESD*2 in both samples was similar (0.105) but the mothers' genotypes were not in Hardy-Weinberg equilibrium (due to an excess of type 2). The ESD allele frequencies in Tasmania are similar to those reported in other white Australian populations.

Alleles↗
PubMedDate not supplied

Restriction fragment length polymorphism at the CALCA locus identified by the probe pEMBL36 in immigrant populations of Australia.

Restriction fragment length polymorphisms detected by the cDNA probe, pEMBL36, at the CALCA locus (calcitonin gene and calcitonin gene related peptide) on TaqI blots were examined in samples from Italian, Greek and Vietnamese migrants to Melbourne, Australia and in a sample of residents from the island of Tasmania, Australia. The frequency of the rarer of the two alleles of this polymorphism, A2 (8.0kb) varied between a low of 6% in Vietnamese to a maximum of 38% in Tasmanians. The frequency range of the A2 allele in European populations, however, was considerably less. Analysis revealed no significant heterogeneity for this polymorphism among either the European or European derived populations, and these combined data exhibited a frequency of 33% for the A2 allele. Though based on a very small Vietnamese sample this study suggests that the A2 allele is less frequent in those of Asian ancestry.

Adult↗
PubMedDate not supplied

ABO-haptoglobin interaction in the white Australian population: further evidence from Tasmania.

A total of 2003 donors from the island state of Tasmania, Australia, were investigated for association between the genetic polymorphisms, ABO and haptoglobin, HP. No interaction between phenotypes of the two systems was found, although the observed deficit of HP*1 in group O has also been noted in the neighbouring Victorian population. When the Tasmanian and Victorian samples were merged to give a large Australian sample (N = 4,211) again no association was found among the phenotypes. However, significant differences were observed in the distributions of both HP phenotypes and alleles between group O and non-O persons respectively.

ABO Blood-Group System↗
PubMedDate not supplied

Effects of grinding, polishing, and overglazing on the flexure strength of a high-leucite feldspathic porcelain.

The objective of this study was to determine how surface treatments and moisture affect the flexure strength of a high-leucite feldspathic porcelain. Uniaxial flexure strength was measured for porcelain beams whose surfaces were coarse ground, overglazed, or polished. Half of the specimens were stored in distilled water and tested while their surfaces were coated with distilled water. The other half were stored in a dry environment and tested immediately in dry air. The high-leucite feldspathic porcelain was found to be sensitive to roughness and surface stresses, similar to leucite-free and low-leucite feldspathic porcelains. The experimental method used, however, was not sensitive enough to detect susceptibility to moisture.

Aluminum Silicates↗