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C Collins

Publications and source records attributed to C Collins.

At least 73 records · Page 4Linked to original sources
PubMed1998

Identification of a gene encoding an acyl CoA:diacylglycerol acyltransferase, a key enzyme in triacylglycerol synthesis.

Triacylglycerols are quantitatively the most important storage form of energy for eukaryotic cells. Acyl CoA:diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) catalyzes the terminal and only committed step in triacylglycerol synthesis, by using diacylglycerol and fatty acyl CoA as substrates. DGAT plays a fundamental role in the metabolism of cellular diacylglycerol and is important in higher eukaryotes for physiologic processes involving triacylglycerol metabolism such as intestinal fat absorption, lipoprotein assembly, adipose tissue formation, and lactation. DGAT is an integral membrane protein that has never been purified to homogeneity, nor has its gene been cloned. We identified an expressed sequence tag clone that shared regions of similarity with acyl CoA:cholesterol acyltransferase, an enzyme that also uses fatty acyl CoA as a substrate. Expression of a mouse cDNA for this expressed sequence tag in insect cells resulted in high levels of DGAT activity in cell membranes. No other acyltransferase activity was detected when a variety of substrates, including cholesterol, were used as acyl acceptors. The gene was expressed in all tissues examined; during differentiation of NIH 3T3-L1 cells into adipocytes, its expression increased markedly in parallel with increases in DGAT activity. The identification of this cDNA encoding a DGAT will greatly facilitate studies of cellular glycerolipid metabolism and its regulation.

3T3 Cells↗
PubMed1998

The human homologue for the Caenorhabditis elegans cul-4 gene is amplified and overexpressed in primary breast cancers.

Amplification is a key mechanism whereby a cancer cell increases the message level of genes that confer a selective advantage when they are overexpressed. In breast cancer, there are many chromosome regions present in multiple copies relative to overall DNA copy number (amplicons), and their target genes are unknown. Using differential display, we have cloned and sequenced the full coding region of a candidate amplicon target gene located on chromosome 13. This candidate is the human homologue of the Caenorhabditis elegans cul-4 gene, cul-4A, a member of the novel cullin gene family, which is involved in cell cycle control of C. elegans. cul-4A was amplified and overexpressed in 3 of 14 breast cancer cell lines analyzed, and it was overexpressed in 8 additional cell lines in which it was not amplified. The latter observation, indicating that its overexpression can occur by mechanisms other than gene amplification, suggests that cul-4A plays a key role in carcinogenesis. Moreover, cul-4A was found to be amplified in 17 of 105 (16%) cases of untreated primary breast cancers, and 14 of 30 cases analyzed (47%) were shown by RNA in situ hybridization to overexpress cul-4A. These results suggest that up-regulation of cul-4A may play an important role in tumor progression.

Amino Acid Sequence↗
PubMed1998

Zf9, a Kruppel-like transcription factor up-regulated in vivo during early hepatic fibrosis.

Wound repair in the liver induces altered gene expression in stellate cells (resident mesenchymal cells) in a process known as "activation." A zinc finger transcription factor cDNA, zf9, was cloned from rat stellate cells activated in vivo. Zf9 expression and biosynthesis are increased markedly in activated cells in vivo compared with cells from normal rats ("quiescent" cells). The factor is localized to the nucleus and the perinuclear zone in activated but not quiescent cells. Zf9 mRNA also is expressed widely in nonhepatic adult rat tissues and the fetal liver. The zf9 nucleotide sequence predicts a member of the Kruppel-like family with a unique N-terminal domain rich in serine-proline clusters and leucines. The human zf9 gene maps to chromosome 10P near the telomere. Zf9 binds specifically to a DNA oligonucleotide containing a GC box motif. The N-terminal domain of Zf9 (amino acids 1-201) is transactivating in the chimeric GAL4 hybrid system. In Drosophila schneider cells, full length Zf9 transactivates a reporter construct driven by the SV40 promoter/enhancer, which contains several GC boxes. A physiologic role for Zf9 is suggested by its transactivation of a collagen alpha1(I) promoter reporter. Transactivation of collagen alpha1(I) by Zf9 is context-dependent, occurring strongly in stellate cells, modestly in Hep G2 cells, and not at all in D. schneider cells. Our results suggest that Zf9 may be an important signal in hepatic stellate cell activation after liver injury.

Amino Acid Sequence↗
PubMed1998

Positional cloning of ZNF217 and NABC1: genes amplified at 20q13.2 and overexpressed in breast carcinoma.

We report here the molecular cloning of an approximately 1-Mb region of recurrent amplification at 20q13.2 in breast cancer and other tumors and the delineation of a 260-kb common region of amplification. Analysis of the 1-Mb region produced evidence for five genes, ZNF217, ZNF218, and NABC1, PIC1L (PIC1-like), CYP24, and a pseudogene CRP (Cyclophillin Related Pseudogene). ZNF217 and NABC1 emerged as strong candidate oncogenes and were characterized in detail. NABC1 is predicted to encode a 585-aa protein of unknown function and is overexpressed in most but not all breast cancer cell lines in which it was amplified. ZNF217 is centrally located in the 260-kb common region of amplification, transcribed in multiple normal tissues, and overexpressed in all cell lines and tumors in which it is amplified and in two in which it is not. ZNF217 is predicted to encode alternately spliced, Kruppel-like transcription factors of 1,062 and 1,108 aa, each having a DNA-binding domain (eight C2H2 zinc fingers) and a proline-rich transcription activation domain.

Amino Acid Sequence↗
PubMed1998

Structural and functional analysis of J chain-deficient IgM.

Previous studies have discerned two forms of polymeric mouse IgM: moderately cytolytic (complement-activating) pentamer, which contains J chain, and highly cytolytic hexamer, which lacks J chain. To investigate the relationships among polymeric structure, J chain content, and cytolytic activity, we produced IgM in J chain-deficient and J chain-proficient mouse hybridoma cell lines. Both hexamer and pentamer were produced in the absence as well as the presence of J chain. Hexameric IgM activated (guinea pig) complement approximately 100-fold more efficiently than did J chain-deficient pentamer, which, in turn, was more active than J chain-containing pentamer. These results are consistent with the hypothesis that J chain-containing pentamer cannot activate complement. We also analyzed the structure of IgM-S337, in which the mu-chain bears the C337S substitution. Like normal IgM, IgM-S337 was formed as a hexamer and as both J chain deficient- and J chain-containing pentamers. Unlike normal IgM, IgM-S337 dissociated in SDS into various subunits. For IgM-S337 pentamer, the predominant subunits migrated as mu2kappa2 and mu4kappa4, and the subunit distribution was unaltered by J chain. However, J chain was found only in the mu2kappa2 species, suggesting that some arrangement of inter-mu bonds directs incorporation of J chain. IgM-S337 hexamer also dissociated to mu2kappa2 and mu4kappa4, but also yielded several species migrating much more slowly in SDS-PAGE than wild-type mu12kappa12. To account for these forms, we propose that each mu-chain can interact with three other mu-chains and that some hexameric molecules contain two catenated mu6kappa6 circles.

Animals↗
PubMed1998

Mechanisms of inactivation of E-cadherin in breast cancer cell lines.

Loss of E-cadherin (CDH1) function is thought to contribute to progression in breast cancer and other solid tumors by increasing proliferation, invasion, and/or metastasis. In some cases, the restoration of CDH1 function may be an important therapeutic option. This possibility will depend on the mechanism by which CDH1 is inactivated. Here we present analyses of CDH1 expression, genetic mutation, and promoter methylation in CDH1 in 10 commonly used breast cancer cell lines. Five cell lines (BT-474, MCF-7, MDA-MB-361, MDA-MB-468, and T-47D) expressed CDH1 and were genetically normal. Five others (SK-BR-3, 600 MPE, MDA-MB-134 IV, CAMA1, and MDA-MB-435) did not express CDH1. Fluorescence in situ hybridization analyses of each of these cell lines showed evidence for the physical deletion of one allele of CDH1, and three cell lines were found to carry homozygous deletions. SK-BR-3 was deleted from exon 12 through the promoter; exon 6 was deleted in MDA-MB-134 IV cells, and 600 MPE cells carried a 21-bp deletion in the splicing acceptor site for exon 9. CAMA1 seemed to have been inactivated through promoter methylation. No explanation was found for the inactivation of CDH1 in MDA-MB-435.

Alleles↗
PubMed1998

Relation between sexual abuse in childhood and adult depression: case-control study.

OBJECTIVE: To examine the association between sexual abuse in childhood and adult depression in women. DESIGN: Two stage, case detection and case identification design, using the 30-item general health questionnaire and the Beck depression inventory for screening and the affective items relating to current functioning on the schizophrenia and affective disorders schedule to identify depressed cases. Details of sexual abuse in childhood were elicited retrospectively by semistructured interview, and social problems by the social problems questionnaire. SETTING: Three general practices, in middle class suburban, deprived inner city, and rural areas. SUBJECTS: 1189 women were screened and 237 subsequently interviewed; 132 were depressed. RESULTS: 49 (37%) of the depressed interviews and 24 (23%) of the non-depressed interviews reported experience of sexual abuse when they were aged under 16 years. A positive association existed between the more severe abuse and depression--all those who had experienced penetration were depressed as adults. A relation was also found between sexual abuse in childhood and sexual problems, housing problems, and problems with their children at school. CONCLUSION: A positive association between child sexual abuse and depression was confirmed, but this was confined to more severe abuse (penetration or attempted penetration).

Adolescent↗
PubMed1998

Fractionated high dose rate brachytherapy moulds--a precise treatment for carcinoma of the pinna.

BACKGROUND AND PURPOSE: The aim of this paper is to describe a fractionated high dose rate brachytherapy procedure for the treatment of small superficial cancers of the pinna and to report the outcome in a small series of patients. MATERIALS AND METHODS: Thirteen patients with superficial cancers of the pinna, not invading cartilage, have been treated and in the majority of cases the tumour thickness was determined by a transdermal ultrasound measurement. For the single-plane moulds the prescribed surface dose was 45 Gy in eight fractions over 5 days and the moulds were constructed such that the full thickness of the disease, as determined by the ultrasound measurement, would lie within the 80% isodose surface. One case was treated with a sandwich mould and in this case the dose was reduced to 42.5 Gy. The treatment machine was a high dose rate microselectron, which contains a single stepping iridium source. RESULTS: The radiation reactions were of moderate severity, but were limited to the high dose volume. In all cases there was complete tumour resolution and rapid healing occurred leaving a barely perceptible scar. There were no recurrences over a minimum follow-up time of 18 months and there were no late radiation complications in this period. CONCLUSIONS: The treatment of superficial carcinoma of the pinna by means of HDR moulds is a safe and reliable technique. In this small series of patients there was total tumour control with excellent cosmesis.

Brachytherapy↗
PubMed1998

Resident human hepatic lymphocytes are phenotypically different from circulating lymphocytes.

BACKGROUND/AIMS: Murine and human studies have documented the existence of subpopulations of lymphocytes in particular tissues that differ phenotypically and functionally from those in peripheral blood and may mature locally. Since little is known about lymphocyte subpopulations in the normal human liver, we have analysed the surface phenotypes of lymphocytes isolated from liver specimens taken from 15 donors at the time of liver transplantation, and compared these with those of peripheral blood lymphocytes. METHODS: Hepatic lymphocytes were prepared by mechanical dissociation and enzymatic digestion of liver tissue. The cells were stained with a panel of monoclonal antibodies (CD3, CD4, CD8, CD19, CD56, gammadeltaTCR, alphabetaTCR, CD8alpha-chain, CD8alphabeta dimer), and analysed by flow cytometry. In situ characterisation of hepatic lymphocytes was by haematoxylin and eosin staining of fixed liver sections and by immunohistochemical staining for common leukocyte antigen and CD3. RESULTS: Significant numbers of hepatic T lymphocytes were localised to the portal tracts and parenchyma of normal liver specimens. Flow cytometry revealed that the CD4/CD8 ratio (1:3.5) was consistently reversed compared with that in peripheral blood (2:1). Other lymphocyte populations identified include double positive CD3+CD4+CD8+ cells which accounted for a mean of 5.5% (range 3-11.6%) of hepatic CD3+ cells compared with 1.3% in blood (range 0.7-3.6%; p < 0.007), and double negative CD3+ CD4-8- cells (14.5%; range 2.7-29% compared with 5.0%; range 2.1-10.8%, p < 0.02). Over 15% (range 6.8-34%) of all hepatic CD3+ cells expressed a gammadeltaTCR compared to 2.7% (range 0.9-4.7%) of CD3+ peripheral blood lymphocytes (p < 0.004) and almost 50% of these coexpressed CD8. The CD8 alpha-chain was expressed without the beta-chain (CD8alpha+beta-) by 15.4% (range 4-29.1%) of hepatic T cells, but this phenotype was undetectable among peripheral blood lymphocytes (p < 0.009). Cells expressing both the T cell marker CD3 and the natural killer cell marker CD56 constituted 31.6% (range 14-54%) of all hepatic CD3+ lymphocytes but were rarely present amongst peripheral blood lymphocytes (0-6%; p < 0.0001). CONCLUSIONS: These data are the first to describe and quantify unconventional T lymphocyte subpopulations in the normal adult human liver which may have specialised functions in regional immune responses and which may differentiate locally. These findings have important implications for our understanding of hepatic immunoregulation and the pathogenic mechanisms involved in viral and immune-mediated liver disease and allograft rejection.

Adolescent↗
PubMed1998

High resolution analysis of DNA copy number variation using comparative genomic hybridization to microarrays.

Gene dosage variations occur in many diseases. In cancer, deletions and copy number increases contribute to alterations in the expression of tumour-suppressor genes and oncogenes, respectively. Developmental abnormalities, such as Down, Prader Willi, Angelman and Cri du Chat syndromes, result from gain or loss of one copy of a chromosome or chromosomal region. Thus, detection and mapping of copy number abnormalities provide an approach for associating aberrations with disease phenotype and for localizing critical genes. Comparative genomic hybridization (CGH) was developed for genome-wide analysis of DNA sequence copy number in a single experiment. In CGH, differentially labelled total genomic DNA from a 'test' and a 'reference' cell population are cohybridized to normal metaphase chromosomes, using blocking DNA to suppress signals from repetitive sequences. The resulting ratio of the fluorescence intensities at a location on the 'cytogenetic map', provided by the chromosomes, is approximately proportional to the ratio of the copy numbers of the corresponding DNA sequences in the test and reference genomes. CGH has been broadly applied to human and mouse malignancies. The use of metaphase chromosomes, however, limits detection of events involving small regions (of less than 20 Mb) of the genome, resolution of closely spaced aberrations and linking ratio changes to genomic/genetic markers. Therefore, more laborious locus-by-locus techniques have been required for higher resolution studies. Hybridization to an array of mapped sequences instead of metaphase chromosomes could overcome the limitations of conventional CGH (ref. 6) if adequate performance could be achieved. Copy number would be related to the test/reference fluorescence ratio on the array targets, and genomic resolution could be determined by the map distance between the targets, or by the length of the cloned DNA segments. We describe here our implementation of array CGH. We demonstrate its ability to measure copy number with high precision in the human genome, and to analyse clinical specimens by obtaining new information on chromosome 20 aberrations in breast cancer.

Animals↗
PubMed1998

Mutations of the forkhead/winged-helix gene, FKHL7, in patients with Axenfeld-Rieger anomaly.

Genetic linkage, genome mismatch scanning, and analysis of patients with alterations of chromosome 6 have indicated that a major locus for development of the anterior segment of the eye, IRID1, is located at 6p25. Abnormalities of this locus lead to glaucoma. FKHL7 (also called "FREAC3"), a member of the forkhead/winged-helix transcription-factor family, has also been mapped to 6p25. DNA sequencing of FKHL7 in five IRID1 families and 16 sporadic patients with anterior-segment defects revealed three mutations: a 10-bp deletion predicted to cause a frameshift and premature protein truncation prior to the FKHL7 forkhead DNA-binding domain, as well as two missense mutations of conserved amino acids within the FKHL7 forkhead domain. Mf1, the murine homologue of FKHL7, is expressed in the developing brain, skeletal system, and eye, consistent with FKHL7 having a role in ocular development. However, mutational screening and genetic-linkage analyses excluded FKHL7 from underlying the anterior-segment disorders in two IRID1 families with linkage to 6p25. Our findings demonstrate that, although mutations of FKHL7 result in anterior-segment defects and glaucoma in some patients, it is probable that at least one more locus involved in the regulation of eye development is also located at 6p25.

Amino Acid Sequence↗
PubMed1998

Members of the olfactory receptor gene family are contained in large blocks of DNA duplicated polymorphically near the ends of human chromosomes.

We have identified three new members of the olfactory receptor (OR) gene family within a large segment of DNA that is duplicated with high similarity near many human telomeres. This segment is present at 3q, 15q, and 19p in each of 45 unrelated humans sampled from various populations. Additional copies are present polymorphically at 11 other subtelomeric locations. The frequency with which the block is present at some locations varies among populations. While humans carry seven to 11 copies of the OR-containing block, it is located in chimpanzee and gorilla predominantly at a single site, which is not orthologous to any of the locations in the human genome. The observation that sequences flanking the OR-containing segment are duplicated on larger and different sets of chromosomes than the OR block itself demonstrates that the segment is part of a much larger, complex patchwork of subtelomeric duplications. The population analyses and structural results suggest the types of processes that have shaped these regions during evolution. From its sequence, one of the OR genes in this duplicated block appears to be potentially functional. Our findings raise the possibility that functional diversity in the OR family is generated in part through duplications and inter-chromosomal rearrangements of the DNA near human telomeres.

Amino Acid Sequence↗
PubMed1998

Frequency of alcohol use and its association with STD/HIV-related risk practices, attitudes and knowledge among an African-American community-recruited sample.

The aim was to determine the association between frequency of alcohol use in the past 30 days and HIV-related risk behaviours among adults in an African-American community. Data were collected by trained street outreach workers, from 522 persons in 4 areas selected on the basis of 7 health and criminal justice indicators of high risk for HIV, STD and substance abuse, and drug-related arrests. A survey assessed demographics, substance use, sexual behaviour, HIV knowledge, attitudes and depression. Subjects reporting using drugs other than alcohol (n=201) were excluded from analyses to avoid the confounding influence of polysubstance use. Of the remaining 321 subjects (mean age=37.1; 58.5% were male), 43.6% reported no alcohol use in the past 30 days, with 37.4% and 19.0%, respectively, having used alcohol < =15 days and = > 16 days in the past 30 days. Alcohol use frequency (no alcohol, 1-15 days, 16-30 days in past month) was significantly associated with being male, STD history, non-use of condoms, higher perceived risk of HIV, lower condom use self-efficacy, multiple sex partners in the past 30 days, and lower HIV-related knowledge. Frequent alcohol use, in the absence of other drugs, is associated with higher levels of HIV risk behaviours. Though an underserved population with respect to HIV prevention and, given the prevalence of alcohol use, the findings suggest that programmes need to target frequent alcohol users to reduce their HIV-associated risk behaviours and enhance HIV risk-reduction knowledge and attitudes associated with the adoption of HIV prevention practices.

Adolescent↗
PubMed1998

Late-life depression in primary care: where do we go from here?

One quarter of elderly patients in the primary care physician's office experience serious depressive symptoms. Despite efforts over the past 20 years to increase detection of late-life depression in primary care settings, patient outcomes have not improved. Undertreatment remains seriously problematic. Current efforts to improve recognition have included the development of depression practice guidelines, Depression Awareness Recognition and Treatment (D/ART) program, educational programs, and rudimentary outcomes measures. Screening tools for depression, such as the Geriatric Depression Scale, the Center for Epidemiologic Studies--Depressed, and Cornell Scale for Depression in Dementia, have also been developed to help clinicians screen for depressive symptoms in both ambulatory and inpatient settings. However, to improve clinical outcomes, increased research efforts should focus upon physicians' attitudes and practice patterns, effective treatments for minor depression, and effective ways to assess patients' perceptions of depression, as well as ways to identify age-specific barriers to treatment adherence. In addition, incorporating valid outcome measures into the primary care clinical setting will be crucial to measure the impact of our treatments.

Aged↗
PubMed1997

ESX: a structurally unique Ets overexpressed early during human breast tumorigenesis.

The >30 known members of the Ets multigene family of transcriptional regulators are increasingly being recognized for their involvement in early embryonic development and late tissue maturation, directing stage-specific and tissue-restricted programs of target gene expression. Identifiable primarily by their 85 amino acid ETS DNA-binding domain and dispersed across all metazoan lineages into distinct subfamilies, Ets genes also produce malignancies in humans and other vertebrates when overexpressed or rearranged into chimeras retaining the ETS domain, suggesting that their oncogenic potential is determined by the program of target genes they regulate. Searching for Ets factors that regulate expression of the HER2/neu (c-erbB2) oncogene in human breast cancer, we identified a new epithelium-restricted Ets encoding an ETS domain homologous to the Drosophila E74/human Elf-1 subfamily, an amino-terminal region (A-region or Pointed domain) homologous to the distantly related Ets-1 subfamily, and a serine-rich box homologous to the transactivating domain of the lymphocyte-restricted High Mobility Group (HMG) protein, SOX4. Recombinant protein encoded by ESX (for epithelial-restricted with serine box) exhibits Ets-like DNA binding specificity in electrophoretic mobility shift assays and, in transient transfection assays, transactivates Ets-responsive promoter elements including that found in the HER2/neu oncogene. ESX is located at chromosome 1q32 in a region known to be amplified in 50% of early breast cancers, is heregulin-inducible and overexpressed in HER2/neu activated breast cancer cells. Tissue hybridization suggests that ESX becomes overexpressed at an early stage of human breast cancer development known as ductal carcinoma in situ (DCIS).

Amino Acid Sequence↗
PubMed1997

Genomic organization, sequence, and chromosomal localization of the human helix-loop-helix Id1 gene.

The helix-loop-helix protein Id-1 regulates growth and differentiation in many mammalian cells. In human fibroblasts, Id1 and Id1', a putative splicing variant, are cell cycle regulated, essential for proliferation, repressed by senescence, and overexpressed by some tumor cells. To better understand Id1, we determined the complete sequence, transcriptional start, and localization of the human Id1 gene. Human Id1 has two exons (426 bp and 42 bp), separated by an intron (239 bp). Id1' results from failure to splice the intron, which encodes 7 amino acids prior to a stop codon. Thus, Id1 and Id1' proteins differ only at the extreme C-terminus. Id1 transcription initiated 96 bp upstream of the initiation AUG; 2 kb of upstream sequence stimulated transcription of a reporter gene. Human Id1 maps to chromosome 20 at q11, very close to the centromere but outside the amplicons frequently found in human cancers.

Amino Acid Sequence↗