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R Fulton

Publications and source records attributed to R Fulton.

At least 19 recordsLinked to original sources
PubMed2004

Optical stark decelerator for molecules.

We demonstrate a single stage optical Stark decelerator for neutral molecules which is capable of reducing the translational energy of benzene molecules within a molecular beam by 15% in a single pulsed Gaussian optical field of 15 ns duration. The change in velocity induced by the optical potential is measured by the change in the time of flight of benzene molecules ionized by a second optical field after the slowing field is turned off. A maximum reduction in the velocity of 25 m/s was measured using a single Gaussian beam with a peak intensity of 1.6 x 10(12) W/cm(2) corresponding to a maximum well depth of 253 K.

Journal Article↗
PubMed2001

Detection of functional PTEN lipid phosphatase protein and enzyme activity in squamous cell carcinomas of the head and neck, despite loss of heterozygosity at this locus.

The human tumour suppressor gene PTEN located at 10q23 is mutated in a variety of tumour types particularly metastatic cases and in the germline of some individuals with Cowdens cancer predisposition syndrome. We have assessed the status of PTEN and associated pathways in cell lines derived from 19 squamous cell carcinomas of the head and neck. Loss of heterozygosity is evident at, or close to the PTEN gene in 5 cases, however there were no mutations in the remaining alleles. Furthermore by Western analysis PTEN protein levels are normal in all of these SCC-HN tumours and cell lines. To assess the possibility that PTEN may be inactivated by another mechanism, we characterized lipid phosphatase levels and from a specific PIP3 biochemical assay it is clear that PTEN is functionally active in all 19 human SCCs. Our data strongly suggest the possibility that a tumour suppressor gene associated with development of SCC-HN, other than PTEN, is located in this chromosomal region. This gene does not appear to be MXI-1, which has been implicated in some other human tumour types. PTEN is an important negative regulator of PI3Kinase, of which subunit alpha is frequently amplified in SCC-HN. To examine the possibility that PI3K is upregulated by amplification in this tumour set we assessed the phosphorylation status of Akt, a downstream target of PI3K. In all cases there is no detectable increase in Akt phosphorylation. Therefore there is no detectable defect in the PI3K pathway in SCC-HN suggesting that the reason for 3q26.3 over-representation may be due to genes other than PI3K110alpha.

Blotting, Western↗
PubMed2001

Evi-1 transforming and repressor activities are mediated by CtBP co-repressor proteins.

Ectopic production of the EVI1 transcriptional repressor zinc finger protein is seen in 4--6% of human acute myeloid leukemias. Overexpression also transforms Rat1 fibroblasts by an unknown mechanism, which is likely to be related to its role in leukemia and which depends upon its repressor activity. We show here that mutant murine Evi-1 proteins, lacking either the N-terminal zinc finger DNA binding domain or both DNA binding zinc finger clusters, function as dominant negative mutants by reverting the transformed phenotype of Evi-1 transformed Rat1 fibroblasts. The dominant negative activity of the non-DNA binding mutants suggests sequestration of transformation-specific cofactors and that recruitment of these cellular factors might mediate Evi-1 transforming activity. C-terminal binding protein (CtBP) co-repressor family proteins bind PLDLS-like motifs. We show that the murine Evi-1 repressor domain has two such sites, PFDLT (site a, amino acids 553--559) and PLDLS (site b, amino acids 584--590), which independently can bind CtBP family co-repressor proteins, with site b binding with higher affinity than site a. Functional analysis of specific CtBP binding mutants show site b is absolutely required to mediate both transformation of Rat1 fibroblasts and transcriptional repressor activity. This is the first demonstration that the biological activity of a mammalian cellular transcriptional repressor protein is mediated by CtBPs. Furthermore, it suggests that CtBP proteins are involved in the development of some acute leukemias and that blocking their ability to specifically interact with EVI1 might provide a target for the development of pharmacological therapeutic agents.

Animals↗
PubMed2001

A physical map of the human genome.

The human genome is by far the largest genome to be sequenced, and its size and complexity present many challenges for sequence assembly. The International Human Genome Sequencing Consortium constructed a map of the whole genome to enable the selection of clones for sequencing and for the accurate assembly of the genome sequence. Here we report the construction of the whole-genome bacterial artificial chromosome (BAC) map and its integration with previous landmark maps and information from mapping efforts focused on specific chromosomal regions. We also describe the integration of sequence data with the map.

Chromosomes, Artificial, Bacterial↗
PubMed2001

Effects of dietary cholesterol restriction in a feline model of Niemann-Pick type C disease.

A feline model of Niemann-Pick disease type C (NPC) was employed to evaluate the effect of dietary cholesterol restriction on progression of disease. Two NPC-affected treated cats were fed a cholesterol-restricted diet beginning at 8 weeks of age; the cats remained on the diet for 150 and 270 days respectively. The study goal was to lower the amount of low density lipoprotein (LDL) available to cells, hypothetically reducing subsequent lysosomal accumulation of unesterified cholesterol and other lipids. Neurological progression of disease was not altered and dietary cholesterol restriction did not significantly decrease storage in NPC-affected treated cats. One NPC-affected treated cat had decreased serum alkaline phosphatase activity (ALP) and decreased serum cholesterol concentration. Liver lipid concentrations of unesterified cholesterol, cholesterol ester and phospholipids in NPC-affected treated cats were similar to those seen in NPC-affected untreated cats. Ganglioside concentrations in the NPC-affected treated cats and NPC-affected untreated cats were similar. Histological findings in liver sections from NPC-affected treated cats showed a diffuse uniform microvacuolar pattern within hepatocytes and Kupffer cells, in contrast to a heterogeneous macro/microvacuolar pattern and prominent nodular fibrosis in NPC-affected untreated cats. Similar differences in vacuolar patterns were seen in splenic macrophages. Although some hepatic parameters were modified, dietary cholesterol restriction did not appear to alter disease progression in NPC-affected kittens.

Alanine Transaminase↗
PubMed2000

Content-based retrieval of dynamic PET functional images.

The recent information explosion has led to massively increased demand for multimedia data storage in integrated database systems. Content-based retrieval is an important alternative and complement to traditional keyword-based searching for multimedia data and can greatly enhance information management. However, current content-based image retrieval techniques have some deficiencies when applied in the biomedical functional imaging domain. In this paper, we presented a prototype design for a content-based functional image retrieval database system for dynamic positron emission tomography. The system supports efficient content-based retrieval based on physiological kinetic features and reduces image storage requirements. This design makes it possible to maintain a large number of patient data sets online and to rapidly retrieve dynamic functional image sequences for interpretation and generation of physiological parametric images, and offers potential advantages in medical image data management and telemedicine, as well as providing possible opportunities in the statistical and comparative analysis of functional image data.

Computer Graphics↗
PubMed2000

Composite dendritic cell neoplasm (NOS) and small lymphocytic lymphoma.

This report describes a composite (or "collision") of a dendritic cell neoplasm and small lymphocytic lymphoma. It represents the seventh example of dendritic cell neoplasia occurring in the setting of low-grade B-cell malignancy and the third example of a composite tumor, in which both neoplasms were present within the same lymph node. The small lymphocytic lymphoma component exhibited a typical CD20+, CD5+, and CD23+ immunophenotype. The dendritic cell neoplasm exhibited reactivity with CNA-42, but nonreactivity for CD21, CD35, smooth muscle actin, desmin, and epithelial membrane antigen (EMA). Equivocal cytoplasmic staining was seen for S100p, CD68, and Factor XIIIa. Ultrastructurally, the dendritic cell neoplasm exhibited desmosomes, rough endoplasmic reticulum, cytoplasmic intermediate filaments, and intercellular collagen. Because the immunophenotype and ultrastructure did not correspond to one of the five recognizable dendritic cell subtypes, the neoplasm was designated dendritic cell neoplasm, not otherwise specified (NOS). Polymerase chain reaction (PCR) analysis for immunoglobulin heavy chain gene rearrangements performed on individual components of the composite tumor demonstrated rearrangement within the small lymphocytic lymphoma component, but none in the dendritic cell component. The lack of an immunoglobulin heavy chain gene rearrangement within the dendritic cell component argues against a transformational event and supports the concept that these separate neoplasms represent a true "collision" or composite lesion.

Aged↗
PubMed1999

The fit-1 common integration locus in human and mouse is closely linked to MYB.

The fit-1 locus was originally identified as a common insertion site for feline leukemia virus (FeLV) in thymic lymphosarcomas induced by FeLV-myc recombinant viruses, suggesting that it harbors a gene that cooperates with Myc in T-cell leukemogenesis. We have previously mapped the fit-1 locus to feline Chromosome (Chr) B2. We have now identified conserved sequences that allow the mapping of the murine homolog using the European Interspecific Backcross (EUCIB). This shows that fit-1 is located on mouse Chr 10, 1cM proximal to Ahi-1, a murine retroviral integration locus that is closely linked to Myb. Moreover, the physical linkage to MYB is maintained in the human genome, as shown by cloning of the human homolog of fit-1 from a Chr 6 cosmid library and a series of overlapping PAC clones. Generation of a contig map around the human homolog of fit-1 reveals that it is approximately 100-kb upstream of MYB. In addition to fit-1 and Ahi-1, two other common insertion sites, Mis-2 and Mml-1, have also been mapped adjacent to Myb on mouse Chr 10. Previous analysis of tumors carrying insertions at fit-1, Mml-1, Mis-2 and Ahi-1 showed no obvious abnormalities in Myb expression. However, the cluster of viral insertion loci in this region suggests either the presence of a closely linked activation target or that subtle effects on Myb have been overlooked.

Animals↗
PubMed1999

Nucleotide sequence of the feline Bmi-1 coding region.

The bmi-1 gene was discovered as a clonal integration site of the Moloney murine leukaemia virus in B-cell lymphomas. The Bmi-1 protein contains the RING finger motif and is homologous to two Drosophila proteins known to be part of a multimeric protein complex involved in repressing gene transcription. A similar role for the highly conserved Bmi-1 protein in mammalian cells has been suggested. The coding regions for the mouse and human genes are known and are 92% homologous. This study involved PCR amplification, cloning, and sequencing of the 980bp feline bmi-1 coding region which was shown to be 92% and 97% homologous to the mouse and human genes respectively. From the open reading frame the feline protein is 326 amino acids in length and is 99% homologous to the human protein and 97% homologous to the mouse protein. This data is consistent with the closer relationship between the feline and human genomes and provides another experimental system in which to analyse Bmi-1 function.

Amino Acid Sequence↗
PubMed1996

Octamer independent activation of transcription from the kappa immunoglobulin germline promoter.

Previous analyses of immunoglobulin V region promoters has led to the discovery of a common octamer motif which is functionally important in the tissue-specific and developmentally regulated transcriptional activation of immunoglobulin genes. The germline promoters (Ko) located upstream of the J region gene segments of the kappa locus also contain an octamer motif (containing a single base pair mutation and referred to as the variant octamer) which has been shown previously to bind Oct-1 and Oct-2 transcription factors in vitro. To further elucidate the role of this variant octamer motif in the regulation of germline transcription from the unrearranged kappa locus, we have quantitated the relative binding affinity of Oct-1 and Oct-2 for the variant octamer motif and determined the functional role of this octamer motif in transcriptional activation. We find that, although the variant octamer motif binds Oct-1 and Oct-2 in vitro with 5-fold lower affinity than the consensus octamer motif, mutation of the variant octamer motif to either a consensus octamer or non-octamer motif has no effect on transcriptional activation from the germline promoter. We also find significant differences in activation of germline and V region promoters by kappa enhancers. Our results suggest that the germline promoters and V region promoters differ in their dependence on octamer for activation and respond differently to enhancer activation. These findings have important implications in regulation of germline transcription as well as concomitant activation of the V-J recombination of the kappa light chain locus.

Animals↗
PubMed1996

Multiple phenotypes associated with Myc-induced transformation of chick embryo fibroblasts can be dissociated by a basic region mutation.

Chimaeric alleles were constructed to assay the biological functions of an N-terminal deletion and C-terminal mutations which were found in a naturally occurring mutant of feline vMyc, T17. The mutant alleles were assayed for their ability to transform chick embryo fibroblasts in vitro by a number of criteria, namely the ability to induce morphological transformation, an accelerated growth rate and growth in soft agar. Feline cMyc could transform the avian cells, whilst T17 vMyc could not, and the N-terminal deletion was responsible for conferring the primary transformation defect on the mutant protein. The C-terminal mutations which consist of a point mutation adjacent to the nuclear localisation signal and a point mutation/amino acid insertion within the basic region (BR) could, however, dissociate the Myc-induced parameters of transformation. This effect was a specific function of the BR mutation alone, and the mutation could be transferred into avian cMyc with comparable biological consequences. The BR mutation did not disrupt the sequence specific DNA binding activity of the protein in vivo, despite exerting a biological effect. These data suggest a novel phenotype where the mutation may affect a subset of Myc-regulated genes through altered DNA binding specificity or protein-protein interactions.

Amino Acid Sequence↗
PubMed1996

Allogeneic marrow transplantation in a cat with acute myeloid leukemia.

A listless, anorectic 2-year-old cat was found to have a normocytic, nonregenerative anemia. A diagnosis of acute myeloid leukemia type M6Er was made. Because the cat was young, had negative FeLV and feline immunodeficiency virus test results, had a sibling that could be used as a bone marrow donor, had received only 1 transfusion, and was in good health other than being anemic, allogeneic bone marrow transplantation (BMT) was attempted using marrow from the cat's sibling. The most life-threatening complication following BMT was hemorrhage caused by severe thrombocytopenia. Complete hematopoietic engraftment was evident 36 days after BMT. The cat then was discharged to its owner. In the first year, the cat continued to improve with the exception of an intractable dermatophytosis, which resolved eventually. The cat continues to do well 4 years after BMT. To our knowledge, this represents the first report of successful allogeneic BMT for a cat with acute myeloid leukemia.

Anemia↗