Biomedical subjects

K J Abel

Publications and source records attributed to K J Abel.

At least 19 recordsLinked to original sources

PubMed2000

Determination of the clearance factor for transmissible spongiform encephalopathy agents during the manufacturing process of polygeline.

OBJECTIVE: To determine the safety of polygeline, a gelatine-derived plasma substitute produced from bovine bones, in terms of safety for bovine spongiform encephalopathy (BSE) by evaluating the ability of the manufacturing process of polygeline to eliminate agents related to transmissible spongiform encephalopathy (TSE) through the validation of three main production steps. DESIGN: Laboratory scale experimental process (in duplicate) using 20% hamster-adapted 263K scrapie-infected brain homogenate as infective titrated source (10(9) LD50/2 ml), added to each material before being processed and titrated in hamsters. Experiment 1: time/temperature dependency of gelatine autoclaving. Experiment 2: cross-linking and distillation. Experiment 3: final sterilization. Monitoring period: 1 year with daily animal clinical observation. Histology of all brains. SETTING: LCG-RBM laboratories, Italy; strict GLP compliance. MEASUREMENTS AND RESULTS: Heating the gelatine (at conditions lower than those used in production process) was very effective in inactivating the infectivity of TSE agents. Clearance factors were reproducible, dependent upon time and temperature, reaching a total theoretical process clearance in the range of 9.2-13.8 [6.9 + 2.3 (+ 4.6)] log10 LD50. CONCLUSIONS: These experimental results provide further important data confirming the safety of the procedural steps; this complements the safety due to the careful sourcing of the raw material. There is high assurance that there is no significant risk of TSE transmission to humans by the therapeutic administration of polygeline.

Animals↗

PubMed1998

Thymic lymphomas in mice with a truncating mutation in Brca2.

Inherited mutations in the BRCA2 gene predispose women to breast and ovarian cancer. We created a mutation in the mouse Brca2 gene that terminates translation in exon 11 at 45% of the normal transcript length. Ninety % of Brca2(tm1Cam) homozygous mutant mice die prenatally or perinatally. The location of the Brca2(tm1Cam) mutation differs from those reported previously, and this phenotype suggests a correlation with genotype analogous to that previously reported in humans. Although heterozygote mice have remained free of tumors for 10 months, Brca2(tm1Cam) homozygous mutants that survived to adulthood died with thymic lymphomas between 12 and 14 weeks of age.

Alleles↗

PubMed1996

Characterization of EZH1, a human homolog of Drosophila Enhancer of zeste near BRCA1.

Recent transcription mapping efforts within chromosome 17q21 have led to the identification of a human homolog of the Drosophila gene Enhancer of zeste, E(z). A member of the Polycomb group (Pc-G) of proteins, Drosophila E(z) acts as a negative regulator of the segment identity genes of the Antennapedia and Bithorax complexes. Here we report the full-length protein coding sequence of human EZH1 (Enhancer of zeste homolog 1) and compare the respective protein sequences in both species. EZH1 encodes a protein of 747 amino acids that displays 55% amino acid identity overall (70% similarity) with Drosophila E(z). The strongest homology was noted (79% identity, 89% similarity) within the carboxy-terminal 245 amino acids, including the SET domain, a region of E(z) also conserved in other Drosophila proteins with roles in development and/or chromatin structure. A large Cysrich region with a novel spatial pattern of cysteine residues was also conserved in both EZH1 and E(z). The strong sequence conservation suggest potential roles for EZH1 in human development as a transcriptional regulator and as a component of protein complexes that stably maintain heterochromatin. EZH1 is expressed as two major transcripts in all adult and fetal human tissues surveyed; comparison of cloned cDNAs suggests that alternative splicing may account for at least part of the transcript size difference. Analysis of one cDNA revealed an unusual splicing event involving EZH1 and a tandemly linked gene GPR2 and suggests a potential mechanism for modifying the EZH1 protein in the conserved C-terminal domain. The sequence and isolated cDNAs will provide useful reagents for determining the function of EZH1 and the importance of the evolutionarily conserved domains.

Adult↗

PubMed1996

Isolation of tetranucleotide repeat polymorphisms flanking the BRCA1 gene.

Large pools of cosmids from the BRCA1 region of human chromosome 17 were screened for tetranucleotide repeat polymorphisms by hybridizing shotgun subcloned pools with a mixture of 25 oligonucleotides. Identified subclones were PCR amplified and directly sequenced to design PCR primers for short tandem repeat polymorphism (STRP) analysis of family DNAs. With the identification of the BRCA1 gene and the observation that most mutations in this > 100-kb gene are unique, haplotyping and linkage analysis may play a significant role in diagnosis and carrier detection of BRCA1-associated breast and ovarian cancers. We report the characterization of 15 new STRPs flanking the BRCA1 locus.

BRCA1 Protein↗

PubMed1995

Structural organization and mapping of the human TCF11 gene.

We recently cloned human cDNA representing several mRNA isoforms of human TCF11, a transcription factor of the basic-region, leucine-zipper (bZIP) family located on chromosome 17q22 as well as a genomic clone of this gene. We have now determined the complete genomic organization of the TCF11 gene, which consists of 9 exons distributed over 15 kb of genomic DNA. Pulsed-field gel electrophoresis was used to construct a physical map around TCF11, to characterize a 450-kb YAC clone that contains the gene, and to link TCF11 physically to BTR, a marker on chromosome 17.

Amino Acid Sequence↗

PubMed1995

Construction of a transcription map surrounding the BRCA1 locus of human chromosome 17.

We have used a combination of methods (exon amplification, direct selection, direct screening, evolutionary conservation, island rescue-PCR, and direct sequence analysis) to survey approximately 600 kb of genomic DNA surrounding the BRCA1 gene for transcribed sequences. We have cloned a set of fragments representing at least 26 genes. The DNA sequence of these clones reveals that 5 are previously cloned genes; the precise chromosomal location of 2 was previously unknown, and 3 have been cloned and mapped by others to this interval. Three other genes, including BRCA1 itself, have recently been mapped independently to this region. Sequences from 11 genes are similar but not identical matches to known genes; 5 of these appear to be the human homologues of genes cloned from other species. Another 7 genes have no similarity with known genes. In addition, 39 putative exons and 14 expressed sequence tags have been identified and mapped to individual cosmids. This transcript map provides a detailed description of gene organization for this region of the genome.

Animals↗

PubMed1995

A YAC-, P1-, and cosmid-based physical map of the BRCA1 region on chromosome 17q21.

A familial early-onset breast cancer gene (BRCA1) has been localized to chromosome 17q21. To characterize this region and to aid in the identification of the BRCA1 gene, a physical map of a region of 1.0-1.5 Mb between the EDH17B1 and the PPY loci on chromosome 17q21 was generated. The physical map is composed of a yeast artificial chromosome (YAC) and P1 phage contig with one gap. The majority of the interval has also been converted to a cosmid contig. Twenty-three PCR-based sequence-tagged sites (STSs) were mapped to these contigs, thereby confirming the order and overlap of individual clones. This complex physical map of the BRCA1 region was used to isolate genes by a number of gene identification techniques and to generate transcript maps of the region, as presented in the three accompanying manuscripts of Brody et al. (1995), Osborne-Lawrence et al. (1995), and Friedman et al. (1995).

BRCA1 Protein↗

PubMed1995

Transcript identification in the BRCA1 candidate region.

Chromosome 17q12-21 is known to contain a gene (or genes) which confers susceptibility to early-onset breast cancer and ovarian cancer (BRCA1). Identification and isolation of BRCA1 will likely provide the basis for increased understanding of the pathogenesis of breast and ovarian cancer, the development of targeted diagnostic and therapeutic approaches, and a means of screening women at risk of being BRCA1 mutation carriers. Genetic and physical maps of the BRCA1 candidate region have been largely completed and efforts are being directed at identification of candidate genes from within this region. We have begun the task of identifying transcripts from this region employing three complementary strategies. These include: 1) direct cDNA screening with cosmids derived from the BRCA1 region; 2) exon amplification; and 3) magnetic bead capture. Transcripts identified using these approaches are being characterized for: 1) tissue expression pattern; 2) the presence of genomic rearrangement in DNA derived from affected members of families believed to show linkage between breast cancer and genetic markers in the BRCA1 candidate interval; 3) altered size and/or expression pattern in RNA prepared from such individuals; and 4) homology to known genes or functional motifs. Germline mutations in affected individuals from these families will serve as presumptive evidence of BRCA1 identity.

Breast Neoplasms↗

PubMed1995

Localization of the human homolog of the yeast cell division control 27 gene (CDC27) proximal to ITGB3 on human chromosome 17q21.3.

The human homolog of the Saccharomyces cerevisiae cell division control 27 gene (CDC27) was mapped to human chromosome 17q12-q21 using a panel of human/rodent somatic cell hybrids and localized distal to the breast cancer susceptibility gene, BRCA1, using a panel of radiation hybrids. The radiation hybrid panel indicates that the most likely position of human CDC27 on human chromosomes 17 is between the marker D17S409 and the beta 3 subunit of integrin (ITGB3). Further confirmation of this localization comes from the sequence tagged site (STS) mapping of human CDC27 to the same yeast artificial chromosomes (YACs) positive for ITGB3. The estimated distance between ITGB3 and human CDC27 is less than 600 kb.

Animals↗

PubMed1995

The developmental pattern of Brca1 expression implies a role in differentiation of the breast and other tissues.

We have examined the developmental expression of the murine breast and ovarian cancer susceptibility gene, Brca1, to investigate its role in the control of cell growth and differentiation. Specifically, we have analysed Brca1 expression during embryonic development, in adult tissues, and during postnatal mammary gland development, particularly in response to ovarian hormones. Our results suggest that Brca1 is expressed in rapidly proliferating cell types undergoing differentiation. In the mammary gland, Brca1 expression is induced during puberty, pregnancy, and following treatment of ovariectomized animals with 17 beta-estradiol and progesterone. These observations imply that Brca1 is involved in the processes of proliferation and differentiation in multiple tissues, notably in the mammary gland in response to ovarian hormones.

Animals↗

PubMed1995

Mouse Brca1: localization sequence analysis and identification of evolutionarily conserved domains.

The human genes BRCA1, conferring susceptibility to early-onset breast and ovarian cancer, has recently been isolated. Here we describe isolation of cDNAs, sequence analysis, and genomic localization of the murine homolog, Brac1. The mouse cDNA sequence predicts a protein of 1812 amino acids; a number of small gaps account for the 51 fewer residues in the mouse protein relative to human BRCA1. While the predicted mouse and human proteins display on the whole a high level of homology (58% identity, 73% similarity), the regions of greatest homology are at the respective amino and carboxyl termini. Most reported disease-associated missense mutations in human BCRA1 occurred within these more highly conserved terminal regions. A predicted zinc-building RING finger domain near the amino terminus lies within a 50 amino acid stretch that is perfectly conserved in both species. The strong conservation during mammalian evolution argues for the importance of this domain, perhaps mediating a role for BRCA1 in DNA and/or protein binding. We have also identified a conserved highly acidic domain in the carboxyl terminal half of the BCRA1 protein resembling acidic transactivation domains of certain transcription factors. Using an interspecific backcross panel, Brca1 was mapped to a region of mouse chromosome 11 that exhibits conserved linkage with 17q21. The sequence and isolated cDNAs will provide useful reagents for studying the expression of Brca1 in the mouse, and for testing the importance of the evolutionarily conserved domains.

Amino Acid Sequence↗

PubMed1994

Familial breast cancer. Approaching the isolation of a susceptibility gene.

Family history is recognized widely as a significant risk factor for the development of breast cancer. A gene (BRCA1), mutations in which confer susceptibility to early-onset breast and ovarian cancer, has been mapped to chromosome 17q12-21. An intensive search for this gene is currently underway in a number of laboratories. Recent data support the hypothesis that BRCA1 is a tumor suppressor gene that may be important in the development of both inherited and sporadic breast and ovarian cancers. Genetic and physical maps of the BRCA1 candidate region largely have been completed and efforts are being directed at identification of candidate genes from within this region. A small number of families recently have received results of genetic-linkage testing, indicating which family members likely are to be carriers of a germline BRCA1 mutation, and, therefore, have a lifetime risk of developing breast cancer of approximately 85%. The imminent isolation of BRCA1 will make predictive testing for breast cancer a reality for many women and likely will pave the way for novel diagnostic and therapeutic strategies in the future.

Breast Neoplasms↗

PubMed1994

Localization of the gene for ATP citrate lyase (ACLY) distal to gastrin(GAS) and proximal to D17S856 on chromosome 17q12-q21.

The gene encoding ATP-citrate lyase, designated ACLY, was mapped to human chromosome 17q12-q21 by PCR on a panel of human/rodent somatic cell hybrids and localized to 17q21.1 by PCR on a panel of radiation hybrids. The radiation hybrid panel indicates that the most likely position of ACLY on 17q21.1 is between gastrin (GAS) and D17S856 at a distance of 170-290 kb from the GAS locus.

ATP Citrate (pro-S)-Lyase↗

PubMed1994

Progress toward isolation of a breast cancer susceptibility gene, BRCA1.

The high incidence of breast cancer and/or ovarian cancer in some families appears to be due to germ-line mutations in BRCA1. Genetic analysis of such families suggests that the BRCA1 candidate region lies between D17S857 and D17S78 on chromosome 17q21 (Kelsell et al. 1993; Simard et al. 1993). To identify and isolate BRCA1, we have used linkage and meiotic recombination analysis, characterized regions displaying LOH in tumor DNA from BRCA1-linked families, performed YAC and cosmid clone isolation and ordering, and used three complementary transcript-searching strategies. We have identified as many as 28 genes from the BRCA1 candidate region, and we are searching for constitutive mutations in these candidate genes by several methods in an attempt to identify BRCA1.

BRCA1 Protein↗

PubMed1993

A chromosome 11 YAC library.

A targeted yeast artificial chromosome (YAC) library for chromosome 11 has been constructed from the J1 cell line that carries a single human chromosome 11 within a hamster DNA background. Interspecies chimeric clones generated during construction of the library were detected during the screening process and eliminated from the library. Contig assembly becomes much less difficult using such a library as the complexity is decreased and the ends of the clone inserts can be rescued for walking to neighboring clones. The library contains > 1824 clones with an average insert length of 337 kb. This represents a fourfold coverage of chromosome 11 or a > 95% chance of recovering a unique single-copy sequence from the library. Two hundred YAC clones were localized by fluorescence in situ hybridization and found to be randomly distributed along the chromosome. The library has been screened with probes for the chromosome 11 markers HBB, GLUR4, H19, and D11S193. Corresponding YAC clones have been isolated for each locus. This analysis has indicated that the library is unbiased, that cognate YAC clones can be recovered with chromosome 11 markers, and that extensive contig assembly should be feasible.

Animals↗

PubMed1993

A radiation hybrid map of the BRCA1 region of chromosome 17q12-q21.

The chromosomal region 17q12-q21 contains a gene (BRCA1) conferring susceptibility to early-onset familial breast and ovarian cancer. An 8000-rad radiation-reduced hybrid (RH) panel was constructed to provide a resource for long-range mapping of this region. A large fraction of the hybrids (approximately 90%) retained detectable human chromosome 17 sequences. The complete panel of 76 hybrids was scored for the presence or absence of 22 markers from this chromosomal region, including 14 cloned genes, seven microsatellite repeats, and one anonymous DNA segment. Statistical analysis of the marker retention data employing multipoint methods provided both comprehensive and framework maps of this chromosomal region, including distance estimates between adjacent markers. The comprehensive RH map includes 17 loci and spans 179 cRays(8000). Likelihood ratios of at least 1000:1 support the 10-locus framework order: cen-D17S250-ERBB2-(THRA1, TOP2A)-D17S855-PPY-D17S190-MTBT1-GP3A++ +-BTR-D17S588-tel. The order obtained from RH mapping, when used in conjunction with other methods, will be useful in linkage analysis of breast cancer families and will facilitate the development of a physical map of this region.

Base Sequence↗

PubMed1993

Linkage of Agt and Actsk-1 to distal mouse chromosome 8 loci: a new conserved linkage.

Angiotensinogen is an alpha 2-globulin involved in the maintenance of blood pressure and electrolyte balance. We have refined the position of the mouse angiotensinogen locus (Agt) on Chromosome (Chr) 8 and have also confirmed the assignment of the human angiotensinogen locus (AGT) to Chr 1. The segregation of several restriction fragment length variants (RFLVs) was followed in two interspecific backcross sets and in four recombinant inbred (RI) mouse sets. Analysis of the segregation patterns closely linked Agt to Aprt and Emv-2, which places the angiotensinogen locus on the distal end of mouse Chr 8. Additionally, a literature search has revealed that the strain distribution pattern (SDP) for the mouse skeletal alpha-actin locus 1 (Actsk-1, previously Acta1, Acta, or Acts) is nearly identical to the SDP for Agt in two RI sets. On the basis of this information we were able to reassign Actsk-1 to mouse Chr 8. By screening a panel of human-mouse somatic cell hybrids, we confirmed that the human angiotensinogen locus lies on Chr 1. This information describes a new region of conserved linkage homology between mouse Chr 8 and human Chr 1. It also defines the end of a large region of conserved linkage homology between mouse Chr 8 and human Chr 16.

Actins↗

PubMed1993

Expression of the mouse Ren-1 gene in the coagulating gland: localization and regulation.

The components of the renin-angiotensin system have been detected in various reproductive tissues of mammals including the testis, epididymis, ovary, and placenta. Using Northern blot and in situ hybridization analyses, we detected abundant levels of renin mRNA in the coagulating gland (anterior prostate) of mice with one (Ren-1) but not two (Ren-1/Ren-2) copies of the renin gene. In contrast to mice, the single renin gene of the rat (R. norvegicus) was silent in the coagulating gland. The results of this survey suggest that the ability of the renin gene to express in the coagulating gland was acquired during the speciation of mice and subsequently lost as a result of the duplication event at the renin locus. In the coagulating gland, we found that renin mRNA transcripts initiated at a series of upstream start sites, some of which map within a 0.5-kb transposable-like element previously identified in the promoter region of the mouse, but not the rat, renin gene. Furthermore, renin gene expression in the coagulating gland was positively regulated by testosterone. The coagulating gland thus represents a male reproductive tissue that demonstrates high-level, species-specific, and differential expression of renin mRNA.

Animals↗