Biomedical subjects

M Frommer

Publications and source records attributed to M Frommer.

At least 19 recordsLinked to original sources

PubMed2005

[The Würzburg polytrauma algorithm. Concept and first results of a sliding-gantry-based computer tomography diagnostic system].

BACKGROUND: The purpose of this study was to show the practicability of a new algorithm in the management of polytraumatized patients based on Advanced Trauma Live Support (ATLS) and using mobile whole body multislice CT (MMDCT) as the primary imaging system. PATIENTS AND METHODS: A series of 120 trauma patients referred to the Würzburg University Hospital Trauma Emergency Room were categorized into suspected polytrauma and suspected non-polytrauma groups. The polytraumatized patients were investigated using the Würzburg polytrauma-algorithm including whole body multislice CT with a 16-row-scanner. The algorithm is described. The time for the diagnostic procedure was measured and compared with data from the Trauma Registry of the German Society of Trauma Surgery. RESULTS: From 120 patients 78 (66%) underwent whole body CT. The diagnostic procedure was quick with significant advantages especially for cranial and trunk diagnostics. CONCLUSION: The Würzburg polytrauma algorithm worked well. There was excellent cooperation within the interdisciplinary leading team consisting of anaesthesiologists, surgeons, and radiologists. The principles of ATLS could be respected. Mobile whole body multislice CT was an effective tool in the diagnostic evaluation of polytrauma patients.

Algorithms↗

PubMed2003

The scarlet eye colour gene of the tephritid fruit fly: Bactrocera tryoni and the nature of two eye colour mutations.

A homologue of the Drosophila melanogaster eye-colour gene, scarlet (st), has been isolated from the genome of the tephritid fruit fly, Bactrocera tryoni. The comparison of the B. tryoni and D. melanogaster scarlet gene shows 71.2% and 79.3% sequence identity at the DNA and the derived amino acid level, respectively. Two allelic eye-colour mutations of B. tryoni, orange-eyes and lemon-eyes, have been recovered and found to be colocalized with the st gene. The st gene sequence in the two mutant strains has been examined for DNA sequence changes and expression levels.

Alleles↗

PubMed2002

Towards a male-only release system for SIT with the Queensland fruit fly, Bactrocera tryoni, using a genetic sexing strain with a temperature-sensitive lethal mutation.

Flies that are homozygous for the recessive autosomal mutation bent wings have a limited ability to fly and are less tolerant of high temperatures than normal flies in both the egg and puparial stages. The differences between the mutant and normal flies were found sufficient to be the basis of a genetic sexing strain. Genetic sexing strains were created using translocations of the autosome bearing the wild-type allele of bent wings (chromosome 2) to the Y chromosome, and crossing male flies carrying the translocation to mutant bent wings females. In the resulting strain, the females were homozygous for the bent wings mutation and the males were phenotypically normal for wing characters. Several translocations were recovered after irradiation, but only one translocation involving chromosome 2 was both stable and expressed in a stock that was vigorous enough for long-term viability. Unfortunately, all stocks containing the translocation showed high levels of temperature-dependent lethality, including, inexplicably, both males and females. Translocation stocks showing this effect included bent wings, another second chromosome mutation, white marks, and an otherwise normal stock. This phenomenon is probably rare, as it has not been reported before. It is likely that bent wings could be suitably used with another translocation.

Animals↗

PubMed2002

The period gene in two species of tephritid fruit fly differentiated by mating behaviour.

The period gene is important for the generation and maintenance of biological rhythms. It served as an ideal candidate for the investigation of the mating time isolation between two sibling Queensland fruit fly species, Bactrocera tryoni and Bactrocera neohumeralis. We have isolated the homologues of the period gene in the two species, and show that their putative amino acid sequences are identical. No length polymorphism was detected in the Thr-Gly repeat region. per mRNA expression, assayed in light-dark diurnal conditions, displayed circadian oscillation in both the head and abdomen of B. tryoni and B. neohumeralis, with the same cycling phase. An alternatively spliced intron was identified in the 3' untranslated region. The effect of temperature on the splicing and mRNA expression was examined.

3' Untranslated Regions↗

PubMed2002

Criteria for evaluating evidence on public health interventions.

Public health interventions tend to be complex, programmatic, and context dependent. The evidence for their effectiveness must be sufficiently comprehensive to encompass that complexity. This paper asks whether and to what extent evaluative research on public health interventions can be adequately appraised by applying well established criteria for judging the quality of evidence in clinical practice. It is adduced that these criteria are useful in evaluating some aspects of evidence. However, there are other important aspects of evidence on public health interventions that are not covered by the established criteria. The evaluation of evidence must distinguish between the fidelity of the evaluation process in detecting the success or failure of an intervention, and the success or failure of the intervention itself. Moreover, if an intervention is unsuccessful, the evidence should help to determine whether the intervention was inherently faulty (that is, failure of intervention concept or theory), or just badly delivered (failure of implementation). Furthermore, proper interpretation of the evidence depends upon the availability of descriptive information on the intervention and its context, so that the transferability of the evidence can be determined. Study design alone is an inadequate marker of evidence quality in public health intervention evaluation.

Evidence-Based Medicine↗

PubMed2001

The genome of the Queensland fruit fly Bactrocera tryoni contains multiple representatives of the mariner family of transposable elements.

Representatives of five distinct types of transposable elements of the mariner family were detected in the genomes of the Queensland fruit fly Bactrocera tryoni and its sibling species Bactrocera neohumeralis by phylogenetic analysis of transposase gene fragments. Three mariner types were also found in an additional tephritid, Bactrocera jarvisi. Using genomic library screening and inverse PCR, full-length elements representing the mellifera subfamily (B. tryoni.mar1) and the irritans subfamily (B. tryoni.mar2) were isolated from the B. tryoni genome. Nucleotide consensus sequences for each type were derived from multiple defective copies. Predicted transposase sequences share approximately 23% amino acid identity. B. tryoni.mar1 elements have an estimated copy number of about 900 in the B. tryoni genome, whereas B. tryoni.mar2 element types appear to be present in low copy number.

Amino Acid Sequence↗

PubMed2001

Microsatellite analysis of the Queensland fruit fly Bactrocera tryoni (Diptera: Tephritidae) indicates spatial structuring: implications for population control.

The population structure of a tephritid pest species, the Queensland fruit fly Bactrocera tryoni (Froggatt), has been analysed over a five year period (1994-1998), using six microsatellites. Adult fly samples were collected to cover most regions of eastern and central Australia where the flies are regularly found. Tests for heterogeneity indicated that flies within geographically defined regions were homogeneous. The samples were allocated into five regions, including one very large region, Queensland, which encompasses that portion of the fly's range where breeding can occur year-round. With one exception, the collections from different regions were homogeneous between years, showing a fairly static distribution of the species. However, differences between regions were highly significant. The one case of a change in frequency between years indicated a gradual replacement of flies in a marginal region by flies from the main part of the range. The finding of stability in the distribution of a highly mobile insect is of interest, potentially also for other species which have expanded beyond their native range. It is argued that a contributing reason for this stability may be adaptation to different climatic regimes, and that strategies for control based on this hypothesis afford a reasonable chance of success.

Animals↗

PubMed2000

Close genetic similarity between two sympatric species of tephritid fruit fly reproductively isolated by mating time.

Two sibling species of tephritid fruit fly, Bactrocera tryoni and B. neohumeralis, occur sympatrically throughout the range of B. neohumeralis in Australia. Isolation between the two species appears to be maintained by a difference in mating time: B. tryoni mates at dusk, whereas B. neohumeralis mates during the middle of the day. A morphological difference in humeral callus color also distinguishes the two species. Despite clear phenotypic evidence that B. tryoni and B. neohumeralis are distinct species, genetic differentiation as measured by four markers--nuclear DNA sequences from the white gene and the ribosomal internal transcribed spacer (ITS2), and mitochondrial DNA sequences from the cytochrome b (cytb) and cytochrome oxidase subunit II (COII) genes--is very small. Minor fixed differences occur in the ITS2 sequence, however, in all other cases the two species exhibit a high level of shared polymorphic variation. The close genetic similarity suggests either that speciation has occurred very rapidly and recently in the absence of any mitochondrial DNA sorting or that the sharing of polymorphisms is due to hybridization or introgression. A third species within the tryoni complex, B. aquilonis, is geographically isolated. Bactrocera aquilonis is also genetically very similar, but in this case there is clear differentiation for the mitochondrial loci. The three species form a group of considerable interest for investigation of speciation mechanisms.

Amino Acid Sequence↗

PubMed1998

Bisulfite sequencing in preimplantation embryos: DNA methylation profile of the upstream region of the mouse imprinted H19 gene.

In this study we describe a modification of the bisulfite genomic sequencing protocol that enables detection of methylation from as few as five diploid cells from preimplantation mouse embryos. We have used bisulfite genomic sequencing to study the methylation profile of the putative imprinting element upstream of the mouse H19 gene at several stages of embryonic development, including fertilized oocytes and two-cell embryos. The methylation of the H19 imprinting element has recently been described extensively for midgestation embryos, but remains poorly characterized for the preimplantation stages of development, despite widespread changes in genomic DNA methylation occurring at this time. We studied the methylation profile of 35 CpG sites spanning two regions within the H19 imprinting element and found that an overall pattern of allele-specific methylation was maintained at all developmental stages examined, including fertilized oocytes and two-cell embryos. However, allele-specific methylation was not maintained in an absolute fashion subsequent to the first cell division, with a clear flux between partial de novo methylation of the maternal allele and partial demethylation of the paternal allele. Our findings highlight the dynamics of methylation in the early embryo and suggest that it is the overall level of methylation that is responsible for maintenance of the imprinting element and not the methylation of individual CpG sites.

Alleles↗

PubMed1998

Sequence-specific methylation of the mouse H19 gene in embryonic cells deficient in the Dnmt-1 gene.

We have used Dnmtc/c ES cells that are homozygous for disruption of the DNA methyltransferase gene to address how de novo methylation is propagated and whether it is directed to specific sites in the early embryo. We examined the imprinted H19 gene and the specific-sequence region implicated as an "imprinting mark" to determine whether de novo methylation was occurring at a restricted set of sites. Since the "imprinting mark" was found to be methylated differentially at all stages of development, we reasoned that the sequence may still be a target for the de novo methylation activity found in the Dnmtc/c cells, even though the loss of maintenance the methylase activity renders the H19 promoter active. We used bisulfite genomic sequencing to determine the methylation state of the imprinted region of the H19 gene and found a low level of DNA methylation at specific single CpG sites in the upstream region of the imprinted H19 sequence in the Dnmtc/c mutant ES cells. Moreover, these CpG sites appeared to be favoured targets for further de novo methylation of neighbouring CpG sites in rescued ES cells, which possess apparently normal maintenance activity. Our data provide further evidence for a separate methylating activity in ES cells and indicate that this activity displays sequence specificity.

Animals↗

PubMed1998

Phylogenetic relationships between oviparous and viviparous populations of an Australian lizard (Lerista bougainvillii, scincidae).

Viviparity has evolved from oviparity in many vertebrate lineages, and species that contain both oviparous and viviparous populations offer the best opportunity for a detailed examination of the processes involved in this major life-history transition. However, although several such species have been reported, none have been the subject of detailed phylogenetic analyses. We examine such a case within the Australian scincid lizard bougainvillii. Data were obtained by sequencing a 314-bp segment of mitochondrial cytochrome b from 32 individuals from 17 populations of L. bougainvillii and two morphologically similar congeneric species (L. dorsalis L. microtus). Sequences were aligned and analyzed using parsimony and distance methods. The resultant matriarchal phylogeny resolved the populations of L. bougainvillii into three major groups: a population from NSW; a group predominantly from Eyre Peninsula; and a less well-defined group from the central part of the species range. The NSW and Eyre Peninsula groups are oviparous and are quite divergent from other L. bougainvillii populations and from each other. The central group contains both viviparous and oviparous populations, and seem to represent a more recent radiation within the species. Our results indicate that viviparity has evolved at least twice within the genus Lerista, because the viviparous L. microtus is not closely related to viviparous populations of L. bougainvillii. The lack of phylogenetic separation of mtDNAs from viviparous and oviparous populations within L. bougainvillii relative to strong geographic structure within the latter indicates that populations with different reproductive modes are indeed conspecific. Lerista bougainvillii is thus the first vertebrate species for which intraspecific bimodality in reproductive mode can be claimed with any certainty.

Animals↗

PubMed1998

The Bactrocera tryoni homologue of the Drosophila melanogaster sex-determination gene doublesex.

A homologue of the bifunctional sex-determining gene, doublesex (dsx), has been identified in the tephritid fruit fly, Bactrocera tryoni, and has been found to be expressed in a sex-specific manner in adult flies. The male- and female-specific cDNAs are identical at their 5' ends but differ at their 3' ends and appear to be the products of alternate splicing. The level of identity of the sex-specific DSX proteins of B. tryoni with the D. melanogaster DSX proteins, across the region corresponding to the DNA binding domain and the oligomerization domains, is greater than 85%. Four sequence motifs which are ten to thirteen bases identical to the TRA/TRA-2 binding sites (thirteen-nucleotide repeat sequences) are present in the female-specific exon of the B. tryoni dsx gene.

Amino Acid Sequence↗

PubMed1998

Polymorphic microsatellite markers for population analysis of a tephritid pest species, Bactrocera tryoni.

To obtain a set of microsatellite markers for the Queensland fruit fly Bactrocera tryoni, a genomic library was screened with a number of simple repeat oligonucleotide probes. Sequencing recovered 22 repeat loci. The microsatellite sequences were short, with repeat numbers ranging from five to 11. Of these, 16 polymerase chain reaction (PCR) primer sets yielded amplifiable products, which were tested on 53 flies from five widely separated sites. All loci showed polymorphism in the population sample, with the number of alleles ranging from two to 16. Several dinucleotide repeats showed alleles separated by single-base differences and multiple steps, suggesting a mutation process more complex than the stepwise mutation model.

Alleles↗

PubMed1998

Mitochondrial control-region sequence variation in aboriginal Australians.

The mitochondrial D-loop hypervariable segment 1 (mt HVS1) between nucleotides 15997 and 16377 has been examined in aboriginal Australian people from the Darling River region of New South Wales (riverine) and from Yuendumu in central Australia (desert). Forty-seven unique HVS1 types were identified, varying at 49 nucleotide positions. Pairwise analysis by calculation of BEPPI (between population proportion index) reveals statistically significant structure in the populations, although some identical HVS1 types are seen in the two contrasting regions. mt HVS1 types may reflect more-ancient distributions than do linguistic diversity and other culturally distinguishing attributes. Comparison with sequences from five published global studies reveals that these Australians demonstrate greatest divergence from some Africans, least from Papua New Guinea highlanders, and only slightly more from some Pacific groups (Indonesian, Asian, Samoan, and coastal Papua New Guinea), although the HVS1 types vary at different nucleotide sites. Construction of a median network, displaying three main groups, suggests that several hypervariable nucleotide sites within the HVS1 are likely to have undergone mutation independently, making phylogenetic comparison with global samples by conventional methods difficult. Specific nucleotide-site variants are major separators in median networks constructed from Australian HVS1 types alone and for one global selection. The distribution of these, requiring extended study, suggests that they may be signatures of different groups of prehistoric colonizers into Australia, for which the time of colonization remains elusive.

Humans↗

PubMed1998

Mitotic and polytene chromosome analyses in the Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae).

The Queensland fruit fly, Bactrocera tryoni, like the Mediterranean fruit fly, Ceratitis capitata, has a diploid complement of 12 chromosomes, including five pairs of autosomes and a XX/XY sex chromosome pair. Characteristic features of each chromosome are described. Chromosomal homology between B. tryoni and C. capitata has been determined by comparing chromosome banding pattern and in situ hybridisation of cloned genes to polytene chromosomes. Although the evidence indicates that a number of chromosomal inversions have occurred since the separation of the two species, synteny of the chromosomes appears to have been maintained.

Animals↗

PubMed1997

Hox-type and non-Hox homeobox gene sequences in genomic DNA of the sea urchin Holopneustes purpurescens.

As a preliminary step in an analysis of Hox gene expression and radial body plan specification in sea urchin development, we amplified partial homeobox sequences in H. purpurescens by PCR using degenerate primers. The primers, HoxE and HoxF (Pendleton et al., 1993), spanned a highly conserved region of 82 nucleotides encompassing amino acids 21-47 of the homeodomain. Seven Hox-type homeobox sequences and two non-Hox homeobox sequences were identified. The seven Hox-type sequences were placed provisionally in Hox paralogous groups, one in paralogous group 3, three in paralogous groups 6-8 and three in paralogous groups 9 13. The non-Hox sequences had similarities with Xlox and Gbx homeobox genes.

Animals↗

PubMed1997

Extensive DNA methylation spanning the Rb promoter in retinoblastoma tumors.

The retinoblastoma gene (Rb) is one of the best characterized tumor suppressor genes, and its inactivation is associated with a number of cancers. Previous studies have shown, by restriction enzyme analysis, that the promoter region of the Rb gene is methylated in a significant proportion of primary retinoblastoma tumors. We now report the first detailed methylation sequence analysis of the CpG island spanning the retinoblastoma promoter from hypermethylated retinoblastoma tumors. Our results show methylation is not confined to a specific CpG site, as detected by restriction enzyme studies, but extends to essentially all 27 CpG dinucleotides spanning the retinoblastoma CpG island, including the core promoter. The methylation pattern from each tumor DNA sample is different, ranging from densely to sparsely methylated profiles. Single CpG sites, in particular the E2F transcription factor binding site, as well as blocks of CpGs, were undermethylated in some tumor samples. Possible interference of methylation could be due to the binding of sequence-specific protein factors at these sites in the tumor cells. This study highlights that the dynamics of DNA methylation in cancer cells are clearly different from normal cells and gives an insight into the mechanism of abnormal methylation of CpG islands in cancer cells.

Base Sequence↗

PubMed1997

Interplasmid transposition of the mariner transposable element in non-drosophilid insects.

Plasmid-based transposition assays were performed in developing embryos of the Australian sheep blowfly Lucilia cuprina and the Queensland fruit fly Bactrocera tryoni, using the mariner transposable element from Drosophila mauritiana. Transposition products were recovered that were identical in structure to those recovered from D. melanogaster. Only sequences delimited by the mariner terminal repeats were transposed and all insertions occurred at TA residues, and duplicated these. These are the hallmarks of mariner transpositions observed in the chromosomes of D. melanogaster and D. mauritiana, indicating that the plasmid-based assays are accurate indicators of mariner transposition activity. The recovery of precise transposition products from L. cuprina and B. tryoni demonstrates that mariner should be capable of producing germline transformants in these species. The results obtained from these assays suggests that they will be extremely useful in determining if mariner can transpose in other non-drosophilid insects and for investigating factors that might affect mariner transposition frequency.

Animals↗