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Biomedical subjects

T Burke

Publications and source records attributed to T Burke.

At least 91 records · Page 5Linked to original sources
PubMed1994

Comparative analysis of intra- and interpopulation genetic diversity in Bufo bufo, using allozyme, single-locus microsatellite, minisatellite, and multilocus minisatellite data.

Estimates of genetic diversity within, and of variation among, semi-isolated populations of the common toad (Bufo bufo) were derived and compared across four classes of nuclear genetic markers, including allozymes, microsatellites, and single and multilocus minisatellites. Estimates of multilocus heterozygosity and the number of alleles per locus derived from allozymes were lower than for each class of variable number of tandem repeat (VNTR) markers. The degree of interpopulation genetic divergence as determined by genetic distance was generally concordant across all markers, although interpopulation variance in allozyme allele frequency (as measure by F-statistics) was greater than that documented for each VNTR locus. For both classes of VNTR loci, migration appeared to have less influence than mutation on the extent of interpopulation divergence. Analyses suggest that singly and multiply detected VNTR loci may be highly informative for population-level analyses addressing questions concerning population subdivision and breeding structure.

Animals↗
PubMed1994

Minisatellite DNA markers in the chicken genome. II. Isolation and characterization of minisatellite loci.

The isolation of chicken minisatellites is reported. Two charomid libraries were constructed from fractions of size-selected MboI-digested genomic DNA. A total of 5985 colonies were screened with the multilocus probes 33.6 and 33.15; 137 positives were obtained (2.35%). A total of 55 clones were tested against four unrelated chickens; 30 revealed variable single locus patterns. More detailed characterization was made of 15 probes, which were tested against four families comprising a total of 53 offspring. Of parent/offspring comparisons 51% were informative for segregation. No mutations were detected. Three minisatellites were linked on the same autosome, implying that these loci may occur in clusters, and one was Z chromosome-linked. Heterozygosity and allelic variability were measured in 67 individuals from several different strains and breeds. Mean heterozygosity ranged from 50 to 84%. Minisatellite loci appear to be highly variable in the chicken and should provide highly informative markers in intraspecific crosses in genome mapping studies.

Animals↗
PubMed1994

Perceptions of denture aesthetics: a two-centre study of denture wearers and denture providers.

A study into perceptions of complete dentures was carried out in two dental schools, one in Australia and the other in England. Two-hundred participants were asked to assess photographs of five sets of dentures for age, gender and personality. Results were subjected to a multi-rater kappa statistic. Although no centre was determined to be better than the other, it was highly significant that Australian teachers were confident enough to state that they were unable to determine age or gender from the information supplied.

Adult↗
PubMed1994

An experimental study of reflex variability in selective dorsal rhizotomy.

Significant problems regarding the measurement technique currently used to choose nerve roots for sectioning in the selective dorsal rhizotomy procedure have recently been reported. To better understand the source of these problems, a series of six experiments was performed in which the selective rhizotomy technique was applied to cats that were either intact, decerebrate, or spinalized. Measurements were made before and after partial rhizotomy. In decerebrate preparations, large, spontaneous changes in reflex threshold were observed over short periods of time, especially after partial rhizotomy was performed, and threshold changes greater than 1000% could be observed over 10-minute periods. Using constant-current stimulation of the dorsal root at threshold, the response of each ipsilateral leg muscle demonstrated frequent changes, and changes coincided with the variability in threshold estimation. In addition, very low thresholds were measured (0.1 to 0.25 mA) in half (3 of 6) of these experiments, these measurements being well below the currents customarily used for intraoperative decision making. Stimulation at twice threshold was found to consistently increase the pathological quality of the responses observed. Although intact animals never displayed contralateral responses when stimulated at threshold, such contralateral responses could readily be elicited at twice threshold. These laboratory results raise further doubts regarding the reliability of the measurement techniques now widely used for selective dorsal rhizotomy.

Animals↗
PubMed1994

Minisatellite DNA markers in the chicken genome. I. Distribution and abundance of minisatellites in multilocus DNA fingerprints.

This paper reports the detailed characterization of multilocus minisatellite DNA fingerprints in the chicken. Results are presented of DNA fingerprint segregation analyses carried out in three chicken pedigrees, calculating the number of detected loci, testing for Mendelian inheritance, and cosegregation among fingerprint bands. Two pedigrees (families 1 and 2) were analysed using the Jeffreys probes 33.6 and 33.15 only, and one pedigree (family 3) was analysed using 33.6, 33.15, 3' alpha-globin HVR and M13 protein III gene repeat. Mean band transmission frequencies in families 1 and 2 were near to the Mendelian expectation of 0.5 and no mutations were observed. Family 3 showed transmission frequencies slightly exceeding 0.5. Linkage among bands was higher than observed in some other avian species, with each allele represented by a mean of 1.48 HaeIII fragments. Cosegregation of heterozygous parental fragments representing distinguishable loci followed the expected binomial distribution. The number of minisatellites detectable by the four probes was estimated to be 217. The pattern of cosegregation among those minisatellite loci was tested against that expected for different levels of recombination through the use of a simulation model. We conclude that most minisatellites are unlinked and probably widely dispersed in the chicken genome.

Animals↗
PubMed1993

SPOT: an improved differential screening protocol that allows the detection of marginally induced mRNAs.

We have developed a differential screening technique, single plate one transfer (SPOT), that allows the easy detection of mRNAs induced only 2-fold to 3-fold or less above background. As a model system, we looked at the induction of mRNA by parathyroid hormone (PTH) in ROS 17/2.8 rat osteosarcoma cells. The basis for this technique is to symmetrically spot in quadruplicate, on a single plate, a large number of potentially positive plaques obtained from a primary, conventional screen. We then do only one transfer from this plate in order that there will be minimal variability in DNA transfer. This filter is cut into symmetrical strips so that all clones are multiply represented on each strip. These strips are then hybridized with different probes. Since each strip contains an approximately identical amount of DNA per plaque, it is possible to accurately detect mRNAs that are induced only slightly above background. Additionally, the large sizes of the DNA plaques, as well as spotting each clone serially, contribute to the sensitivity of the technique.

Animals↗
PubMed1992

Multilocus DNA fingerprints in gallinaceous birds: general approach and problems.

Multilocus profiles were investigated in five different species of Galliformes (ring-necked pheasant Phasianus colchicus, Indian peafowl Pavo cristatus, Japanese quail Coturnix coturnix japonica, domestic chicken Gallus gallus, and red grouse Lagopus lagopus scoticus) using two human multilocus probes (33.6 and 33.15) in combination with each of four restriction enzymes (AluI, DdeI, HaeIII or HinfI). All the species show a DNA fingerprint-like pattern using at least one restriction enzyme in combination with each multilocus probe. The number of bands detected and the value of the index of similarity for each species differ significantly between the profiles obtained with each multilocus probe. Some enzyme/probe combinations reveal strong cross-hybridization of the multilocus probes with satellite or satellite-like DNA sequences in pheasant, peacock, quail and chicken, which partially or completely prevented scoring of the profile. The choice of restriction enzyme was found to influence the number of bands, the value of the index of similarity and the probability of obtaining an identical fingerprint between unrelated individuals. The Mendelian inheritance and independent segregation of the fragments detected using AluI was investigated in three species (ring-necked pheasant, Indian peafowl and red grouse). Some bands were shown to be tightly linked. An extreme case was encountered in the red grouse, where 12 of the 15 bands scored in one parent represented only two, apparently allelic, haplotypes and so derived from a single locus. However, fingerprint patterns will often be adequate for use in paternity analyses, such as in behavioural studies, despite the occurrence of haplotypic sets of bands. Identical DNA multilocus profiles were sometimes observed between captive-bred siblings in one species. These results emphasize the desirability of determining, in each new species, the optimal experimental conditions as a preliminary to any behavioural or population genetic studies that use the multilocus DNA fingerprinting methodology.

Animals↗
PubMed1992

Human autoantibodies against desmoplakins in paraneoplastic pemphigus.

Recently, a previously unrecognized autoantibody mediated blistering disease, paraneoplastic pemphigus has been described. Paraneoplastic pemphigus is associated with lymphoid malignancies, thymomas, and poorly differentiated sarcomas. Serum of affected patients contain pathogenic autoantibodies that immunoprecipitate from normal keratinocytes a characteristic complex of four polypeptides with M(r) of 250, 230, 210, and 190 kD. As our preliminary studies indicated that the 250-kD and the 210-kD antigens comigrated with desmoplakins I and II, we investigated the possibility that autoantibodies against the desmoplakins were a component of this autoimmune syndrome. 11 sera from affected patients were tested by indirect immunofluorescence against desmosome containing tissues, immunoprecipitation of metabolically labeled keratinocytes, and Western immunoblotting of desmoplakins I and II that had been purified to homogeneity from pig tongue epithelium. By indirect immunofluorescence, 9 of 11 sera showed strong binding to epithelial and nonepithelial desmosomes, and 2 were weakly reactive. All 11 immunoprecipitated 250- and 210-kD bands of variable intensity that comigrated with bands identified by a murine monoclonal antidesmoplakin antibody, and immunoblotting confirmed binding of the serum autoantibodies to purified desmoplakins. This demonstrates that paraneoplastic pemphigus is the first human autoimmune syndrome in which autoantibodies against the desmoplakins are a prominent component of the humoral autoimmune response.

Animals↗
PubMed1992

Dentists' attitudes to cross-infection control.

The wearing of gloves by dentists undertaking clinical procedures has been recommended by many authorities as an essential element of dental surgery cross-infection control. This paper reports an investigation into patterns of glove-wearing by practising dentists, and considers the effect of practice location and practising arrangements on this issue and other aspects of cross-infection control. The results show that these factors, including the type of patient treated, may influence the pattern of glove-wearing by dentists in England and Wales. These findings suggest that groups least likely to follow the recommended infection control procedures should be targeted when assessing dental education requirements.

Attitude of Health Personnel↗
PubMed1991

Multilocus and single locus minisatellite analysis in population biological studies.

In this review we describe the situations in which minisatellite analysis is of value to studies of population and evolutionary biology. Evolutionary and population biologists need to be able to quantify genetic relationships among individual organisms at many different levels, from close familial relationships to evolutionarily distant phylogenetic ones. The use of minisatellite markers is put into this context and compared with the other molecular biological techniques. Examples of the use of multilocus minisatellite analysis in population biology are described. The limitations of multilocus fingerprinting are presented, together with the potential advantages of locus-specific probes. The use of locus-specific probes in population biology is now often feasible due to the recent development of a cloning system which allows their efficient isolation. The availability of locus-specific probes should significantly expand the role of minisatellite markers in population biology.

Animals↗
PubMed1991

Hypervariable minisatellite DNA sequences in the Indian peafowl Pavo cristatus.

We report here for the first time the large-scale isolation of hypervariable minisatellite DNA sequences from a non-human species, the Indian peafowl (Pavo cristatus). A size-selected genomic DNA fraction, rich in hypervariable minisatellites, was cloned into Charomid 9-36. This library was screened using two multilocus hypervariable probes, 33.6 and 33.15 and also, in a "probe-walking" approach, with five of the peafowl minisatellites initially isolated. Forty-eight positively hybridizing clones were characterized and found to originate from 30 different loci, 18 of which were polymorphic. Five of these variable minisatellite loci were studied further. They all showed Mendelian inheritance. The heterozygosities of these loci were relatively low (range 22-78%) in comparison with those of previously cloned human loci, as expected in view of inbreeding in our semicaptive study population. No new length allele mutations were observed in families and the mean mutation rate per locus is low (less than 0.004, 95% confidence maximum). These loci were also investigated by cross-species hybridization in related taxa. The ability of the probes to detect hypervariable sequences in other species within the same avian family was found to vary, from those probes that are species-specific to those that are apparently general to the family. We also illustrate the potential usefulness of these probes for paternity analysis in a study of sexual selection, and discuss the general application of specific hypervariable probes in behavioral and evolutionary studies.

Animals↗
PubMed1991

Chromite ore processing residue in Hudson County, New Jersey.

Chromite ore processing residue occurs at over 130 sites in Hudson County, New Jersey. Many of these sites are in urban residential areas. This waste is a result of 70 years of chromate and bichromate chemical manufacturing. At least 15% of the sites contain total chromium concentrations greater than 10,000 mg/kg, with hexavalent content ranging from about 1 to 50%. Continuing leaching of this waste results in yellow-colored surface water runoff and yellow deposits on the soil surface and inside basement walls. The chemistry, environmental fate, health effects, and human exposure potentials for this waste are described.

Chromium↗
PubMed1991

Doxorubicin resistance conferred by selective enhancement of intracellular glutathione peroxidase or superoxide dismutase content in human MCF-7 breast cancer cells.

To examine the role of doxorubicin-stimulated oxyradical formation in tumor cell killing, we introduced glutathione peroxidase (GSH Px) or superoxide dismutase (SOD) into MCF-7 cells by "scrape loading." Control cytoplasmic GSH Px and SOD levels increased from (mean +/- S.E.) 0.37 nmol/min/mg and 0.58 microgram SOD/mg, respectively, to 3.99 or 7.63 nmol/min/mg and 1.40 or 1.83 micrograms SOD/mg after treatment with either 150 or 300 units/ml of GSH Px or 20 or 40 mg/ml SOD. Resistance to doxorubicin was correlated with the level of GSH Px introduced into the MCF-7 cells; a one-hour exposure to 1.75 microM doxorubicin decreased the cloning efficiency of control cells loaded with medium alone to 34%, whereas doxorubicin-treated cells augmented with 150 or 300 units/ml of GSH Px had plating efficiencies of 56 or 86%, P less than 0.05. Introduction of SOD increased MCF-7 resistance to doxorubicin similarly. The heat-inactivated enzymes were not protective. Cells loaded with GSH Px were also resistant to the redox cycling anticancer quinone mitomycin C but not to the redox inactive analogs 5-iminodaunorubicin and mitoxantrone, suggesting that amplification of GSH Px or SOD levels can produce doxorubicin resistance in MCF-7 cells.

Breast Neoplasms↗
PubMed1990

Proximal femoral replacement for pathological fracture.

Nine patients presented to our unit with extensive metastatic destruction of the proximal femur. The extent of bone loss precluded the use of standard methods of fixation. We undertook proximal femoral replacement as a palliative treatment to restore mobility and relieve pain. Six patients mobilized satisfactorily postoperatively. Three patients did not regain independent mobility and died within 4 weeks of surgery. The major complication was dislocation, which occurred in two patients. The mean postoperative survival was 8 months. We believe proximal femoral replacement is a useful palliative procedure in selected cases of metastatic disease of the femur.

Adult↗
PubMed1990

Drinking water contamination and the incidence of leukemia: an ecologic study.

An ecologic study was performed to examine the relation between the incidence of leukemias and the occurrence of volatile organic chemical (VOC) contamination of drinking water supplies within a study area comprised of subpopulations differentially exposed to drinking water VOCs (trichloroethylene and related solvents). Populations served by community water supplies were classified into exposure categories according to VOC contamination status based on 1984-85 sampling data. Leukemia incidence data (1979-84) were collected from a population-based cancer registry. For females, the standardized incidence ratio was elevated only in towns in the highest of three exposure categories. No association was observed in males in any of the exposure categories. A Poisson regression analysis of the data, using finer exposure strata, indicated an increase in risk among females with increasing level of contamination which appeared to be distributed evenly across all age strata. The rate ratio for females at the highest exposure stratum for total non-THM VOCs compared to the least exposed stratum was 1.68. The observed association appears to suggest that drinking water contaminated with VOCs may increase the incidence of leukemia among exposed females, but caution is advised in the interpretation of these results because of the uncertainties inherent in ecologic studies.

Adult↗