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Biomedical subjects

M Stark

Publications and source records attributed to M Stark.

At least 19 recordsLinked to original sources
PubMed2006

Mutation of the tumour suppressor p33ING1b is rare in melanoma.

BACKGROUND: The p33ING1b gene is involved in the p53-dependent response to DNA damage following exposure to ultraviolet radiation, and has recently been reported to be mutated in 20% of melanoma tumours. OBJECTIVES: We sought to assess the p33ING1b mutation rate in our large panels of fresh melanomas and melanoma cell lines. METHODS: We screened 83 primary melanomas and 55 melanoma cell lines for mutations in p33ING1b by single-strand conformational polymorphism analysis and by direct sequencing. RESULTS: In contrast to previous reports, we found no somatic p33ING1b mutations in our panel of melanomas. We found that some of the discrepancy between our results and previously published studies may be due to inadvertent amplification of the ING1 pseudogene (INGX), and/or contamination of some samples with murine Ing1. CONCLUSIONS: p33ING1b mutations in melanoma are rare. We have highlighted the importance of allele-specific primer design to avoid pseudogene amplification, and also the necessity to confirm the genetic identity and species of origin of individual cell lines. Further studies are needed to clarify the possible role of p33ING1b in melanoma tumorigenesis.

Animals↗
PubMed2005

Activation of the MAPK pathway is a common event in uveal melanomas although it rarely occurs through mutation of BRAF or RAS.

In contrast to cutaneous melanoma, there is no evidence that BRAF mutations are involved in the activation of the mitogen-activated protein kinase (MAPK) pathway in uveal melanoma, although there is increasing evidence that this pathway is activated frequently in the latter tumours. In this study, we performed mutation analysis of the RAS and BRAF genes in a panel of 11 uveal melanoma cell lines and 19 primary uveal melanoma tumours. In addition, Western blot and immunohistochemical analyses were performed on downstream members of the MAPK pathway in order to assess the contribution of each of these components. No mutations were found in any of the three RAS gene family members and only one cell line carried a BRAF mutation (V599E). Despite this, mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK), ERK and ELK were constitutively activated in all samples. These data suggest that activation of the MAPK pathway is commonly involved in the development of uveal melanoma, but occurs through a mechanism different to that of cutaneous melanoma.

Blotting, Western↗
PubMed2004

[Detection and identification of the pathogenic cause of a brain abscess by molecular genetic methods].

Brain abscesses are life-threatening and detection and identification of the causative pathogens are crucial for substantiating the diagnosis and for selecting the optimal antibiotic regimen. In approximately 20% of the patients microbiological cultures of abscess material remain sterile. The polymerase chain reaction (PCR) provides a methodological alternative, but data about the use of broad spectrum PCR assays to detect the causative pathogens in brain abscesses are rare. We report on the case of a 65-years-old patient with a brain abscess caused by Fusobacterium spp., which was only diagnosed by broad spectrum PCR. To our knowledge this is the second report about a brain abscess, where Fusobacterium spp. was identified only by broad spectrum PCR and subsequent DNA sequencing.

Aged↗
PubMed2004

The genome of Desulfotalea psychrophila, a sulfate-reducing bacterium from permanently cold Arctic sediments.

Desulfotalea psychrophila is a marine sulfate-reducing delta-proteobacterium that is able to grow at in situ temperatures below 0 degrees C. As abundant members of the microbial community in permanently cold marine sediments, D. psychrophila-like bacteria contribute to the global cycles of carbon and sulfur. Here, we describe the genome sequence of D. psychrophila strain LSv54, which consists of a 3 523 383 bp circular chromosome with 3118 predicted genes and two plasmids of 121 586 bp and 14 663 bp. Analysis of the genome gave insight into the metabolic properties of the organism, e.g. the presence of TRAP-T systems as a major route for the uptake of C(4)-dicarboxylates, the unexpected presence of genes from the TCA cycle, a TAT secretion system, the lack of a beta-oxidation complex and typical Desulfovibrio cytochromes, such as c(553), c(3) and ncc. D. psychrophila encodes more than 30 two-component regulatory systems, including a new Ntr subcluster of hybrid kinases, nine putative cold shock proteins and nine potentially cold shock-inducible proteins. A comparison of D. psychrophila's genome features with those of the only other published genome from a sulfate reducer, the hyperthermophilic archaeon Archaeoglobus fulgidus, revealed many striking differences, but only a few shared features.

Arctic Regions↗
PubMed2003

Ocular melanoma is not associated with CDKN2A or MC1R variants--a population-based study.

Germline variants in the melanocortin 1 receptor gene (MC1R) and the p16 gene (CDKN2A) are associated with an increased risk of cutaneous melanoma. The frequency of these germline variants was examined in a population-based, incident series of 62 ocular melanoma cases and ethnicity-matched population controls. In both cases and controls, 59% of individuals carried at least one MC1R variant and there were no significant differences in the frequency of any of the five most common variants of MC1R. We also found no significant differences between cases and controls in the frequency of any of the four most common variants of CDKN2A, and no melanoma case carried a deleterious germline CDKN2A mutation. Our findings argue against an important predisposing effect of the MC1R and CDKN2A genes for ocular melanoma.

Aged↗
PubMed2003

The uninsured and Medicaid Oregon tobacco user experience in a real world, phone based cessation programme.

OBJECTIVE: To describe the experience of uninsured and Medicaid Oregon tobacco users who registered in Free & Clear (F&C), a telephone based cessation programme including five scheduled outbound calls. DESIGN AND SETTING: Using a retrospective cohort design, 1334 (423 uninsured, 806 Medicaid, and 105 commercially insured) Oregon tobacco users who registered in F&C between 18 November 1998 and 28 February 2000 were identified and followed for 12 months post-registration; 648 (48.6%) were successfully contacted at 12 months. Information was collected from the F&C database. Unconditional logistic regression, adjusted for race and education, was used. RESULTS: The seven day quit rate at 12 months, assuming non-respondents were smokers, was 14.8% (95% confidence interval (CI) 13.0 to 16.9). This rate was significantly higher among commercially insured participants (v Medicaid but not uninsured) and among participants who completed > or = 5 calls (v < 5 calls). The quit rate for those contacted at 12 months was 30.6% (95% CI 27.0% to 34.3%) and varied, however not significantly, by insurance and number of calls. After adjustment, respondents who completed > or = 5 calls were 60% more likely to quit tobacco (odds ratio (OR) 1.6, 95% CI 0.9 to 3.1), and uninsured respondents who completed > or = 5 calls were 70% more likely to quit tobacco (OR 1.7, 95% CI 0.9 to 3.5), relative to those who completed < 5 calls, but the difference was not significant. CONCLUSIONS: The quit rates are similar to those reported in efficacy trials. The observed variation in quitting tobacco for respondents by number of calls completed and by insurance merits further investigation concentrating on increasing compliance with the call schedule, particularly for the uninsured.

Adult↗
PubMed2001

Prostate epithelial cell lines form spheroids with evidence of glandular differentiation in three-dimensional Matrigel cultures.

Normal (PNT2-C2) and metastatic (PC-3) prostate cell lines were grown in Matrigel to observe the effects on morphology and phenotype in comparison to monolayer culture. In monolayer cultures, PNT2-C2 showed typical round/cuboidal epithelial morphology, with tight cell associations, whereas in Matrigel they formed smooth spheroids, tightly packed with cells. In both monolayer and Matrigel, PNT2-C2 had a differentiated luminal epithelial phenotype with high expression of cytokeratin 8, prostate specific antigen (PSA), prostate specific membrane antigen (PSMA), E-cadherin and desmoglein. In contrast, PC-3 cells possessed an epithelial/mesenchyme morphology in monolayer with loose cell to cell contact and pseudopodial extensions. Immunohistochemical phenotyping indicated the cells were undifferentiated, expressing high levels of vimentin, beta1 integrin, CD44 and low expression of cytokeratin 8. In Matrigel they formed smooth and irregular spheroids, which had a lumen surrounded by a single cell layer. Matrigel also influenced the expression of PSA, PSMA and CD44. These results indicate that Matrigel culture can induce morphological differentiation of prostate cancer cells which initially had a basal phenotype.

Cell Differentiation↗
PubMed2001

MC1R genotype modifies risk of melanoma in families segregating CDKN2A mutations.

Mutations in the exons of the cyclin-dependent kinase inhibitor gene CDKN2A are melanoma-predisposition alleles which have high penetrance, although they have low population frequencies. In contrast, variants of the melanocortin-1 receptor gene, MC1R, confer much lower melanoma risk but are common in European populations. Fifteen Australian CDKN2A mutation-carrying melanoma pedigrees were assessed for MC1R genotype, to test for possible modifier effects on melanoma risk. A CDKN2A mutation in the presence of a homozygous consensus MC1R genotype had a raw penetrance of 50%, with a mean age at onset of 58.1 years. When an MC1R variant allele was also present, the raw penetrance of the CDKN2A mutation increased to 84%, with a mean age at onset of 37.8 years (P=.01). The presence of a CDKN2A mutation gave a hazard ratio of 13.35, and the hazard ratio of 3.72 for MC1R variant alleles was also significant. The impact of MC1R variants on risk of melanoma was mediated largely through the action of three common alleles, Arg151Cys, Arg160Trp, and Asp294His, that have previously been associated with red hair, fair skin, and skin sensitivity to ultraviolet light.

Alleles↗
PubMed2001

Localization of a susceptibility gene for familial nonmedullary thyroid carcinoma to chromosome 2q21.

The familial form of nonmedullary thyroid carcinoma (NMTC) is a complex genetic disorder characterized by multifocal neoplasia and a higher degree of aggressiveness than its sporadic counterpart. In a large Tasmanian pedigree (Tas1) with recurrence of papillary thyroid carcinoma (PTC), the most common form of NMTC, an extensive genomewide scan revealed a common haplotype on chromosome 2q21 in seven of the eight patients with PTC. To verify the significance of the 2q21 locus, we performed linkage analysis in an independent sample set of 80 pedigrees, yielding a multipoint heterogeneity LOD score (HLOD) of 3.07 (alpha=0.42), nonparametric linkage (NPL) 3.19, (P=.001) at marker D2S2271. Stratification based on the presence of at least one case of the follicular variant of PTC, the phenotype observed in the Tas1 family, identified 17 such pedigrees, yielding a maximal HLOD score of 4.17 (alpha=0.80) and NPL=4.99 (P=.00002) at markers AFMa272zg9 and D2S2271, respectively. These results indicate the existence of a susceptibility locus for familial NMTC on chromosome 2q21.

Carcinoma, Papillary↗
PubMed2001

Peptide repertoire of human cerebrospinal fluid: novel proteolytic fragments of neuroendocrine proteins.

Polypeptides in human cerebrospinal fluid (CSF), isolated by phase separation in chloroform-methanol-water and reversed-phase HPLC, were characterised by sequence analysis and mass spectrometry. This identified the presence of peptide fragments of testican, neuroendocrine specific protein VGF, neuroendocrine protein 7B2, chromogranin B/secretogranin I, chromogranin A, osteopontin, IGF-II E-peptide and proenkephalin. The majority of these fragments were generated by proteolysis at dibasic sites, suggesting that they are derived by activities related to prohormone convertase(s). Several of the fragments have previously not been detected, and their functions in CSF or elsewhere are unknown. A characteristic feature of all these fragments is a very high content of acidic residues, in particular glutamic acid. In addition to the fragments of neuroendocrine proteins, endothelin-binding receptor-like protein 2, ribonuclease 1, IGF-binding protein 6, albumin, alpha1-acid glycoprotein 1, prostaglandin-H2 D-isomerase, apolipoprotein A1, transthyretin, beta2-microglobulin, ubiquitin, fibrinopeptide A, and C4A anaphylatoxin were found.

Chromatography, Gel↗
PubMed2001

Comparison of apraxia in corticobasal degeneration and progressive supranuclear palsy.

OBJECTIVE: To describe ideomotor apraxia in patients with corticobasal degeneration and those with progressive supranuclear palsy, two parkinsonian disorders that are often misdiagnosed due to the overlap in their clinical features, and to determine whether systematic apraxia testing is useful for differential diagnosis. METHODS: Fourteen patients fulfilling National Institute of Neurological Disorders and Stroke-Society for Progressive Supranuclear Palsy clinical criteria for progressive supranuclear palsy, 13 patients fulfilling modified Lang criteria for corticobasal degeneration, and 12 normal healthy control subjects were given the Test of Oral and Limb Apraxia, which was scored according to the Florida Apraxia Battery for occurrence of various types of apraxic errors. RESULTS: Both patients with progressive supranuclear palsy and corticobasal degeneration committed a greater number of apraxic errors than normal healthy control subjects on both transitive and intransitive tasks (p < 0.001 in both cases), but apraxia was much more severe in patients with corticobasal degeneration than progressive supranuclear palsy (p < 0.001). The index of apraxia severity, in combination with the assessment of the two key features of progressive supranuclear palsy (falls and vertical gaze palsy), correctly classified all patients. CONCLUSIONS: Patients with corticobasal degeneration show more severe ideomotor apraxia than patients with progressive supranuclear palsy, and systematic assessment of ideomotor apraxia facilitates the differential diagnosis between patients with progressive supranuclear palsy and those with corticobasal degeneration.

Aged↗
PubMed2001

From images to interactions: high-resolution phase imaging in tapping-mode atomic force microscopy.

In tapping-mode atomic force microscopy, the phase shift between excitation and response of the cantilever is used as a material-dependent signal complementary to topography. The localization of information in the phase signal is demonstrated with 1.4-nm lateral resolution on purple membrane of Halobacterium salinarum in buffer solution. In a first-order approximation, the phase signal is found to correlate with modulations of the tip oscillation amplitude, induced by topography. Extending the analysis to contributions of the tip-sample interaction area as a second-order approximation, a method is proposed to extract information about the interaction from the phase signal for surfaces with a roughness in the order of the tip radius.

Buffers↗
PubMed2001

Functional T lymphocytes infiltrate implanted polyvinyl alcohol foams during surgical wound closure therapy.

Vacuum-assisted closure involving the implantation of polyvinyl alcohol foam is a technique recently developed for the treatment of patients suffering from either wound infection or chronic wounds. This method has been shown to improve and accelerate wound healing. However, little is known about the cell populations that infiltrate the foam, and their potential role in resolving the infection and promoting granulation tissue formation. Our study demonstrates that wound-implanted foams are mainly infiltrated with granulocytes, but that mononuclear cells, including macrophages and minor populations of T, B and natural killer lymphocytes, are also present. We show that foam-infiltrating T cells, especially CD4(+) T cells, constitute a phenotypically and functionally heterogeneous population influenced by wound-infecting bacteria. Thus, T lymphocytes could play a role in wound cleansing. In addition, our data indicate that implanted polyvinyl alcohol foams might be suitable microenvironments for manipulating T cell-mediated immune responses in patients.

Adult↗
PubMed2001

Reduction potential of microbial, odour and ammonia emissions from a pig facility by biofilters.

The intention of this study was the determination of the potential to reduce specific microbial bioaerosol (cultivable bacteria and fungi, total cell counts of microbes, airborne endotoxins and microbial volatile organic compounds, MVOC), odour and ammonia emissions from a pig facility by biofilters. Five identical biofilter units in half technical scale were filled with different filter materials (Biochips, coconut-peat, wood-bark, pellets + bark and compost) and connected in parallel to a piggery. The results showed obvious differences between the filter materials. Numbers of airborne cultivable bacteria were decreased by ca. 70 to 95% and the total counts of bacterial cells from ca. 25 to (>) 90%. The total amount of fungal cells was reduced by at least 60%, although the percentage of cultivable moulds in the air after passing the filters was sometimes higher than before. Airborne endotoxins and MVOC were effectively reduced by all filter materials to at least 90%. Regarding odour, the average reduction was between 40 and 83%, whereas only one of the filters proved to be capable of slightly reducing the ammonia emissions. No relationships between odour/ammonia and microbial bioaerosols with regard to the reduction efficiency of the different filter materials or the total load of the emitted air could be established. A tendency could be shown, that biofilters best capable to reduce odour emitted slightly more airborne bacteria, both cultivable and total cell counts.

Air Pollutants↗
PubMed2001

The Edinburgh Mouse Atlas: using the CD.

This paper provides a simple introduction to the reconstructions and data-handling tools stored on the Edinburgh Mouse Atlas CD, together with some of the ways in which the viewers and software can be used to understand mouse development and analyse data. The key aspect of the Mouse Atlas is that the underlying models are a complete representation of the histology, which has not been constrained to a particular interpretation. This means, for example, that the current anatomy domains can be further subdivided as required to any resolution up to the resolution of the models (2-7 microm). In the CD of the early embryos described here, virtually all tissues that can be usefully distinguished either by the histology or morphologically have been delineated.

Animals↗
PubMed2001

Experimental prostate epithelial morphogenesis in response to stroma and three-dimensional matrigel culture.

To reproduce the structural and functional differentiation of human prostatic acini in vivo, prostatic epithelial and stromal cells derived from human primary cultures were cocultured in Matrigel. In the absence of stroma and serum, epithelial spheroids composed of solid masses of stratified and cuboidal cells formed. Outer cells of the spheroid expressed cytokeratins 1, 5, 10, and 14, whereas the inner cells expressed cytokeratin 18. The addition of 2% serum induced formation of a lumen surrounded by a layer of one or two cuboidal and columnar epithelial cells. The further addition of stromal cultures, dihydrotestosterone, and estrogen induced polarization of the epithelium and increased spheroid-forming efficiency. Epithelium expressed either cytokeratin 18 alone or additionally cytokeratins 1, 5, 14, and 10. All spheroid epithelium expressed prostate-specific antigen and prostate-specific membrane antigen. Androgen receptor was only detected in the presence of stroma, serum, and hormones. Thus, development of a functional and morphologically correct prostate gland in vitro is dependent on extracellular matrix, steroid hormones, and factors from stromal cells and serum.

Animals↗