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Biomedical subjects

M Dean

Publications and source records attributed to M Dean.

At least 343 records · Page 19Linked to original sources
PubMed1990

Multiple mutations in highly conserved residues are found in mildly affected cystic fibrosis patients.

We have identified three different point mutations in the coding region of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Each mutation segregates with the disease in two- or three-generation pedigrees and is not found on the normal chromosome of any documented cystic fibrosis carrier. One of the mutations is found in two independent families that contain at least one individual with a mild course of disease. All of these alterations replace charged amino acids with less polar residues and are found in the putative transmembrane sections of the molecule. The mutated amino acids are found to be conserved in both rodents and amphibians and lie in a region of CFTR that is believed to form a channel in the membrane. Although these alterations are rare, they provide important clues to functionally important regions of the molecule.

Adenosine Triphosphate↗
PubMed1990

A frame-shift mutation in the cystic fibrosis gene.

Cystic fibrosis (CF) is a common recessive lethal genetic disorder, affecting 1 in 1,600 Caucasians. The disease causes defective regulation of chloride-ion transport in exocrine cells. Although in all CF families the disease is linked to a locus on chromosome 7q31, there is clinical heterogeneity in the severity of the disease and the age at which it is diagnosed. CF is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. A three-nucleotide deletion (delta F508) causing the loss of a phenylalanine residue in the tenth exon of the CFTR gene has been found on 70% of CF chromosomes. We have now characterized a CF family in which neither parent of the affected individual carries the common mutation, and identified a two-nucleotide insertion in the CF allele of the mother. The mutation introduces a termination codon in exon 13 of the CFTR gene at residue 821, and is predicted to result in the production of a severely truncated nonfunctional protein.

Alleles↗
PubMed1990

Approaches to localizing disease genes as applied to cystic fibrosis.

Using chromosome jumping and walking and restriction fragment length polymorphism (RFLP) analysis, we have defined the region which must contain the cystic fibrosis gene. DNA segments spanning approximately 250 kb in the direction of the gene were isolated and used to identify several new polymorphisms informative in cystic fibrosis families. These RFLPs include a highly polymorphic, CA/GT repeat, and a 10 bp insertion uncovered using the polymerase chain reaction. By analyzing a family with a recombination near the gene, we can exclude this region as containing the mutation. Data on the extent of linkage disequilibrium of these markers provides additional information on where the gene is located.

Base Sequence↗
PubMed1990

Prenatal diagnosis and linkage disequilibrium with cystic fibrosis for markers surrounding D7S8.

Three polymorphic DNA markers surrounding the D7S8 locus were tested for their usefulness in the diagnosis of cystic fibrosis (CF) by linkage analysis. The markers correspond to the loci D7S424 and D7S426. These polymorphisms were studied by centers in the U.S., the United Kingdom, the Netherlands, and Italy, using samples from populations throughout Europe and North America. The additional information provided by these probes increased the heterogeneity of the region from 50% to 58% and was essential for a completely informative diagnosis in one family. A very high degree of linkage disequilibrium was found between these markers, which span a distance of approximately 250 kb. In addition, linkage disequilibrium with CF was noted. Significant heterogeneity of linkage disequilibrium was found among the populations, both for the marker-marker pairs and between the markers and CF.

Cystic Fibrosis↗
PubMed1990

Monocyte-derived neutrophil chemotactic factor (MDNCF/IL-8) resides in a gene cluster along with several other members of the platelet factor 4 gene superfamily.

Monocyte-derived neutrophil chemotactic factor (MDNCF/IL-8, suggested gene symbol IL8) is a cytokine that chemoattracts and activates neutrophils. Using a panel of human-rodent cell hybrids that preferentially segregate human chromosomes and in situ hybridization, the MDNCF/IL-8 gene was placed on the human gene map at position 4q12-q21. This is the same location where at least three other members (platelet factor 4, melanoma growth stimulatory activity, and interferon-gamma induced factor) of the platelet factor 4 gene super-family reside. In addition, a restriction fragment length polymorphism was identified using MDNCF as a probe in screening genomic DNA digested with HindIII from unrelated individuals.

Chemotactic Factors↗
PubMed1990

An oncogenic chromosome 8-9 gene fusion isolated following transfection of human ovarian carcinoma cell line DNA.

Transfection of NIH3T3 cells with genomic DNA from the human ovarian adenocarcinoma tumor cell line OVCAR-3 identified ovc, a rearranged human DNA sequence which was generated during transfection and which induced both morphological transformation and tumorigenesis. A human alu repeat positive 10.5 kb EcoRI fragment present in all transformants was cloned, and two alu-free fragments of 1.8 kb and 2.2 kb were subcloned. The cloned 10.5 kb fragment is not biologically active in DNA transfection assays. Probe from the 2.2 kb fragment hybridizes to poly A + RNA from the transformants and several human tumor cell lines, including OVCAR-3. The 2.2 kb fragment maps to a site on human chromosome 9 (9p24) not known to contain oncogenic sequences, and identifies a two allele polymorphic restriction site. The 1.8 kb fragment maps to human chromosome 8. The ovc transforming sequences fail to hybridize to probes to any of 14 known oncogenes, indicating that they may represent a previously unknown human transforming gene.

Blotting, Northern↗
PubMed1990

New restriction fragment length polymorphism (probe E9) reveals the highest linkage disequilibrium in Italian CF patients.

We report that the allele distribution for RFLP's flanking the CF gene differs between patients with and without pancreatic insufficiency. The present study confirms this difference. In both classes the linkage disequilibrium (LD) is highest with the RFLP revealed by probe E9. The haplotype distribution identified by these RFLP's can be used for indirect carrier detection.

Cystic Fibrosis↗
PubMed1989

Identification of the cystic fibrosis gene: chromosome walking and jumping.

An understanding of the basic defect in the inherited disorder cystic fibrosis requires cloning of the cystic fibrosis gene and definition of its protein product. In the absence of direct functional information, chromosomal map position is a guide for locating the gene. Chromosome walking and jumping and complementary DNA hybridization were used to isolate DNA sequences, encompassing more than 500,000 base pairs, from the cystic fibrosis region on the long arm of human chromosome 7. Several transcribed sequences and conserved segments were identified in this cloned region. One of these corresponds to the cystic fibrosis gene and spans approximately 250,000 base pairs of genomic DNA.

Animals↗
PubMed1989

Tyrosine kinase oncogenes abrogate interleukin-3 dependence of murine myeloid cells through signaling pathways involving c-myc: conditional regulation of c-myc transcription by temperature-sensitive v-abl.

Retroviral expression vectors carrying the tyrosine kinase oncogenes abl, fms, src, and trk abrogate the requirements of murine myeloid FDC-P1 cells for interleukin-3 (IL-3). Factor-independent clones constitutively express c-myc in the absence of IL-3, whereas in parental cultures c-myc transcription requires the presence of the ligand. To directly test the effect of a tyrosine kinase oncogene on c-myc expression, retroviral constructs containing three different temperature-sensitive mutants of v-abl were introduced into myeloid IL-3-dependent FDC-P1 and 32D cells. At the permissive temperature, clones expressing temperature-sensitive abl behaved like wild-type abl-containing cells in their growth properties and expressed c-myc constitutively. Temperature shift experiments demonstrated that both IL-3 abrogation and the regulation of c-myc expression correlated with the presence of functional v-abl. Induction of c-myc expression by reactivation of temperature-sensitive v-abl mimicked c-myc induction by IL-3 in that it did not require protein synthesis and occurred at the level of transcription, with effects on both initiation and a transcription elongation block. However, v-abl-regulated FDC-P1 cell growth differed from IL-3-regulated growth in that c-fos and junB, which are normally induced by IL-3, were not induced by activation of v-abl.

Animals↗
PubMed1989

Isolation of additional polymorphic clones from the cystic fibrosis region, using chromosome jumping from D7S8.

The cystic fibrosis (CF) locus has been located, by both linkage analysis and physical mapping, to a 900-kb region of 7q22-31 flanked by D7S8 (J3.11) and D7S23 (XV-2c). Using a 100-kb general jumping library, we isolated two sequential jump clones, J31 and J29, to one side of the D7S8 region and one jump clone, J32, to the other side of D7S8, so that the total region covered is about 300 kb. Three new RFLPs were detected by J29 and J32. Using PFGE mapping and the three jump clones, we found it possible to orient D7S8 on the chromosome and, by linkage analysis, to further narrow the CF region by 100 kb. The orientation of D7S8 will be useful for directing the isolation of other jump clones toward the CF locus. Though the newly described RFLPs are in considerable linkage disequilibrium with D7S8 polymorphisms, they increase the informativeness of genetic markers in the D7S8 region and should be useful in prenatal diagnosis.

Chromosomes, Human, Pair 7↗
PubMed1989

Loss of heterozygosity at the c-raf locus in small cell lung carcinoma.

The c-raf-1 oncogene is located at chromosome 3p25, near a region known to be specifically deleted in patients with renal cell carcinoma and small cell lung carcinoma (SCLC). From cytogenetic analyses of SCLC cell lines, we have estimated that one c-raf-1 allele was deleted in approximately 80% of the cases. However, c-raf-1 was generally thought to be distal to the most common deletion in SCLC, 3p14-23. Using restriction site polymorphisms (RFLPs) located within the c-raf-1 locus, we have examined DNA from 84 human lung carcinomas. In an analysis of 11 paired (normal versus tumor) SCLC DNA samples, all five informative cases showed loss of heterozygosity at this locus in the corresponding tumor sample. Analysis of 73 unpaired lung carcinoma DNAs showed that out of 31 non-SCLC samples, 19% were heterozygous for the BglI polymorphism and 25% showed heterozygosity with TaqI. However, all of the 42 SCLC samples were homozygous for both of these RFLPs. This striking loss of heterozygosity at the c-raf-1 locus in SCLC indicates that one allele of c-raf-1 is deleted in SCLC. The kinase activity of the c-raf protein appears to be constitutively activated in these cells. Whether this apparent activation results from genetic or epigenetic events is under investigation.

Carcinoma, Small Cell↗
PubMed1989

The human chromogranin A gene: chromosome assignment and RFLP analysis.

Chromogranin A/secretory protein I (CgA) is a glycoprotein that is stored and released along with peptide hormones and neurotransmitters from several tissues, although its exact function is not known. A cDNA (gene symbol CHGA) clone was used as a probe in Southern blot analyses of human-rodent somatic cell hybrid DNAs. Discordancy analysis allowed confirmation of the assignment of the gene to chromosome 14. These results were extended using in situ chromosome hybridization, and a signal was found at 14q32. BglII digestion of genomic DNA from 28 unrelated Caucasian individuals probed with CHGA detected a two-allele RFLP with allelic frequencies of .34 and .66.

Blotting, Southern↗