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Biomedical subjects

D R Edwards

Publications and source records attributed to D R Edwards.

At least 109 records · Page 6Linked to original sources
PubMed1988

Developmental expression of 2ar (osteopontin) and SPARC (osteonectin) RNA as revealed by in situ hybridization.

2ar has been identified as a gene inducible by tumor promoters and growth factors in a variety of cultured mouse cell lines (Smith, J. H., and D. T. Denhardt. 1987. J. Cell. Biochem. 34:13-22). Sequence analysis shows that it codes for mouse osteopontin, an RGDS-containing, phosphorylated, sialic acid-rich Ca++-binding protein originally isolated from bone (Oldberg, A., A. Franzen, and D. Heinegard. 1986. Proc. Natl. Acad. Sci. USA. 83:8819-8823; Prince, C. W., T. Oosawa, W. T. Butler, M. Tomana, A. S. Brown, and R. E. Schrohenloer. 1987. J. Biol. Chem. 262:2900-3907.). In this paper we use Northern blot analysis and in situ hybridization to localize expression of 2ar during mouse embryogenesis. 2ar RNA is first detected in developing limb bones and calvaria at 14.5 d p.c., in a population of cells distinct from those expressing SPARC (osteonectin). High levels of 2ar expression are also seen in the bone marrow-derived granulated metrial gland cells of the deciduum and placenta, and in a number of epithelial tissues, including embryonic and postnatal kidney tubules, uterine epithelium and sensory epithelium of the embryonic ear. The temporal and spatial pattern of 2ar expression seen in vivo suggests that the protein plays a wider role than previously realized, in processes which are not confined to bone development.

Animals↗
PubMed1988

Characterization of the mouse met proto-oncogene.

The DNA sequence of cDNA clones prepared from transcripts of the mouse met proto-oncogene reveals that the mouse met gene encodes a 1380 amino acid protein with the characteristics of a growth factor receptor. This protein can be divided into several putative domains, including an intracellular protein tyrosine kinase domain, a transmembrane domain and a 929 amino acid extracellular domain, possessing a potential proteolytic cleavage site with the sequence Lys-Arg-Arg-Lys-Arg-Ser. To gain additional insights into the function of the met protein we have examined the level of met transcripts in tissues of the late-gestation mouse conceptus. Transcription of met was observed in most of the tissues analysed, but the highest levels of met mRNA were detected in the yolk sac, amnion and kidney; no transcripts were detectable in the calvaria. Chromosomal localization using a series of mouse-hamster hybrid cell lines has demonstrated that met is located on mouse chromosome 6.

Amino Acid Sequence↗
PubMed1988

Autism in association with fragile X syndrome in females: implications for diagnosis and treatment in children.

Fragile X syndrome is the second most common chromosomal cause of mental retardation (MR). The calculated incidence is 1/1000, making accurate and early diagnosis important for specific preventive, pharmacologic, and cognitive treatment. The timely diagnosis in males is facilitated by the characteristic phenotype and an association with autism. In contrast, in females heterozygous for fragile X, the characteristic phenotype and infantile autism are rarely reported. We present two females with cytogenetic expression of the fragile X chromosome for whom the studies were performed because of the presence of autism or prominent autistic features and a behavioral and physical phenotype consistent with fragile X syndrome. The first female, age three years, has autism, hyperactivity, echolalia, language delay, hand stereotypies, and mild MR. The characteristic phenotype was not present nor was there a family history of X-linked MR. Fragile X expression was 6% in the proband, 3% in the mother and 1% (normal) in the father. The second child, seven years old, has prominent autistic features, hyperactivity, mild MR, mild language disorder, and a family history consistent with X-linked MR. Fragile X expression was 3% in the proband and 0% in the mother. These cases support the occurrence of fragile X in autistic females and emphasize the importance of cytogenetic screening for fragile X in this high risk population. Early diagnosis of fragile X allows precise genetic counseling and more specific cognitive and pharmacologic treatment.

Autistic Disorder↗
PubMed1987

Evidence that post-transcriptional changes in the expression of mitogen regulated protein accompany immortalization of mouse cells.

Primary mouse embryo fibroblasts passed in culture go through a period of declining growth rate and then after a period of minimal proliferation begin to grow again, generating, under appropriate conditions, an immortal 3T3 line. The 3T3 cells, but not the primary mouse embryo fibroblasts, are able to synthesize and to secrete mitogen regulated protein (MRP, also known as proliferin). We report here that the level at which the change in gene expression occurs during this spontaneous immortalization process is post-transcriptional, reflecting a change in either RNA processing or transcript stability. To our knowledge, this is the first report of an alteration at the post-transcriptional level of gene expression that accompanies immortalization.

Animals↗
PubMed1987

Transforming growth factor beta modulates the expression of collagenase and metalloproteinase inhibitor.

Exposure of quiescent MRC-5 human fibroblasts to growth factors such as epidermal growth factor, basic fibroblast growth factor or embryonal carcinoma-derived growth factor resulted in the induction of mRNA transcripts encoding the metalloproteinases collagenase and stromelysin and the specific metalloproteinase inhibitor TIMP, whilst expression of collagen and fibronectin was relatively unaffected. Exposure of quiescent cells to growth factors in the presence of transforming growth factor beta (TGF-beta) resulted in inhibition of collagenase induction and a synergistic increase in TIMP expression. TGF-beta alone did not significantly induce metalloproteinase or TIMP expression. These effects on mRNA transcripts were reflected in increased secretion of TIMP protein and collagenase activity. Nuclear run-off analysis of growth factor-induced transcription revealed that the TGF-beta modulation of TIMP and collagenase expression was due to transcriptional mechanisms. The observations suggest that TGF-beta exerts a selective effect on extracellular matrix deposition by modulating the action of other growth factors on metalloproteinase and TIMP expression.

Cell Line↗
PubMed1986

A growth-responsive gene (16C8) in normal mouse fibroblasts homologous to a human collagenase inhibitor with erythroid-potentiating activity: evidence for inducible and constitutive transcripts.

We present the DNA sequence of an essentially full-length cDNA clone of 16C8, a growth factor-inducible gene isolated from a mouse embryo fibroblast cDNA library. The 0.9-kb mRNA encodes an Mr 22,500 protein that has substantial homology to a human protein with the reported abilities to potentiate erythroid differentiation and to inhibit collagenases and other tissue metalloproteinases. The N-terminus of the predicted protein has a hydrophobic nature characteristic of secreted proteins, and two potential sites for N-linked glycosylation are present. The cytoplasmic concentration of 16C8 mRNA is maximal in mid G1 at about 6 h after serum stimulation of quiescent fibroblasts. Northern blot analysis showed a progressive reduction in the size of the induced 16C8 transcripts with increasing time after serum stimulation. This was shown to be due to the reduction in length of the poly(A) tails. S1 analysis of the 5' portion of the mRNA revealed the presence of three different species of transcript, only one of which was inducible.

Amino Acid Sequence↗
PubMed1986

Synthesis and stability of nuclear matrix proteins in resting and serum-stimulated Swiss 3T3 cells.

The major [35S]methionine-radiolabeled nuclear matrix proteins of mouse 3T3 cells were isolated, and most of these were found to be similar in molecular weight, charge, and protease fingerprint to the nuclear matrix proteins of African green monkey kidney cells, which are found tightly bound to simian virus 40 chromosomes. These nuclear matrix proteins were found to be synthesized in quiescent and serum-stimulated cells and to be turned over slowly during pulse-chase experiments. In contrast, a 70-Kd (kilodalton) neutral protein identified as lamin a was found to be turned over rapidly, producing a 68-Kd protein with a similar isoelectric point. In addition, we observed a decrease in the amounts of two chromatin-bound matrix proteins and a relative increase in lamin a following labeling in the presence of 2 micrograms/ml actinomycin D. However, these effects do not appear to be a result of inhibition of transcription, since they were not observed with other inhibitors (alpha-amanitin and 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole).

Amanitins↗
PubMed1986

Developmental intervention: a pediatric clinical review.

We have attempted to review developmental intervention for pediatricians in a way that is of clinical relevance to primary care pediatricians. In so doing, we chose not to evaluate certain topics such as therapeutic intervention for handicapped children or center-based educational programs because these have been adequately addressed elsewhere. It is clear that pediatricians have a unique and important role to play in developmental intervention for the following reasons: pediatricians have easy and routinely accepted access to infants and families in the prenatal, perinatal, and preschool periods: pediatricians possess a socially accepted role of authority; and pediatricians can integrate understanding of the child's health and developmental status within the context of the family and social environment to make clinical interpretation regarding the child's developmental status and prognosis. Pediatricians are thus in the best position to convince parents of their impact on their child's development. The following general roles have been identified for pediatricians. First, pediatricians should be aware of the child's biologic status and family environmental situation and the relative degree of risk for developmental problems. This clinical awareness, in combination with the use of appropriate screening instruments of the child's development and family environment, will allow clinical judgment regarding the frequency and type of child health supervision, the need for further diagnostic evaluation, and the need for referral to intervention programs and other resources. Second, the pediatrician should develop an approach for developmental intervention for all children, whatever their degree of biological risk. This review of medical, educational, and psychological literature demonstrate the following recurring important themes as goals for primary intervention: Improve parental understanding of normal child development and developmental expectations. Assist parent's understanding of the individual developmental characteristics and temperamental style of their child. Promote parental sensitivity to the social nature of infant behaviors. Encourage parent responsiveness to the social behaviors. Improve parental feelings of confidence and competence to affect their child's development. Pediatricians can be influential in supporting structural changes that can have beneficial effects on children's development. Support of humanization of obstetric and nursery practices, and the increased use of child health supervision to parents in groups are examples of such efforts.(ABSTRACT TRUNCATED AT 400 WORDS)

Child↗
PubMed1986

Close relationship of the major excreted protein of transformed murine fibroblasts to thiol-dependent cathepsins.

Complementary DNA clones corresponding to 638 nucleotides of the messenger RNA encoding the major portion of murine major excreted protein have been isolated and sequenced. The amino acid sequence of a part of the murine major excreted protein deduced from the DNA sequence reveals substantial and significant homology with the cysteine proteases actinidin, rat cathepsin H, and papain. Since the amount of murine major excreted protein secreted by cultured cells is often enhanced by transformation, it is implicated in oncogenic phenomena and may play a role in the metastatic process by virtue of its proteolytic activity.

Amino Acid Sequence↗
PubMed1985

A study of mitochondrial and nuclear transcription with cloned cDNA probes. Changes in the relative abundance of mitochondrial transcripts after stimulation of quiescent mouse fibroblasts.

From a cDNA library constructed in pBR322 we have isolated and studied a set of clones corresponding to mRNAs whose abundance changes when serum-deprived murine fibroblasts are stimulated to enter the cell cycle. A subset of these clones was derived from mRNA species whose abundance decreased during the G1 period following serum stimulation; all but one of these clones turned out to be clones of mitochondrial poly(A)mRNAs. There was no detectable change in the rate of transcription of the mitochondrial genome compared with the nuclear genome, and the lengths of the poly(A) segments on both mRNA species did not change significantly after serum stimulation. We conclude that the apparent decline in the relative abundance of the mitochondrial mRNAs is the result of a relative increase in the processing and/or transport of nuclear mRNA.

Animals↗
PubMed1985

A pBR322-derived vector for cloning blunt-ended cDNA: its use to detect molecular clones of low-abundance mRNAs.

In place of the unique Pst I site in pBR322, we have engineered by GC tailing a unique Sma I site bracketed by Pst I sites. The resulting vector, pDE61, and an improved derivative with greater symmetry around the Sma I site, pDE613, have been used to clone blunt-ended duplex cDNA molecules in Escherichia coli in an efficient manner (5 X 10(5) clones from 1 microgram of double-stranded cDNA). When DNA is cloned into the Sma I site, the ability of both vectors to confer ampicillin resistance is lost. Evidence suggests that functional beta-lactamase is made only after the GC-rich sequence containing the Sma I site is deleted: an insert in the Sma I site prevents this. Libraries in either vector, with single or multiple inserts, can be used to generate amplified amounts of cloned heterogeneous cDNA for screening other "target" libraries in a non-homologous vector (e.g., a Bacillus subtilis vector) for cDNA clones of low-abundance mRNAs. Species as infrequent as 0.003% can be readily detected by colony hybridization.

Cloning, Molecular↗
PubMed1985

Transcriptional regulation of two serum-induced RNAs in mouse fibroblasts: equivalence of one species to B2 repetitive elements.

We obtained eight cDNA clones that define five genes whose expression (appearance of transcripts in the cytoplasm) is enhanced when quiescent mouse fibroblasts are stimulated with serum to divide. Two of these clones (designated 49C8 and 16C8) correspond to RNA species that are present in the cytoplasm of quiescent cells at very low levels. After serum stimulation, the level of 16C8 mRNA rose more rapidly than that of 49C8 RNA, reaching a maximum around 6 to 12 h. The data suggest that 49C8 and 16C8 RNAs are induced as a result of independent stimuli. Either fibroblast growth factor or 12-tetradecanoylphorbol-13-acetate alone could induce 16C8 expression almost as effectively as serum; in contrast, 49C8 was not efficiently induced by epidermal growth factor, fibroblast growth factor, insulin, or 12-tetradecanoylphorbol-13-acetate. Inhibitors of transcription and translation diminished the induction of 16C8, while 49C8 expression was sensitive to actinomycin D but not cycloheximide or 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole. In vitro transcription experiments with isolated nuclei revealed a peak in transcriptional activity of the 16C8 gene at around 3 h after serum stimulation. Sequence analysis of the 49C8 cDNA clone showed greater than 90% homology of a large portion to a consensus rodent B2 repetitive element.

Animals↗
PubMed1985

Characterization of a cDNA clone encoding murine mitogen-regulated protein: regulation of mRNA levels in mortal and immortal cell lines.

Mitogen-regulated protein (MRP) is secreted by certain immortal murine cell lines (Swiss 3T3, BNL) stimulated with serum or particular growth factors. We have identified a cDNA clone that encodes part of the protein and have confirmed that MRP is closely related to, if not identical to, the prolactin-related protein designated proliferin. MRP is not produced by primary mouse embryo fibroblasts to nearly the same extent as it is produced by many immortal or transformed lines. Control of expression of this protein by growth factors is achieved both by regulating the extent of transcription and by regulating the processing of the protein.

Animals↗
PubMed1982

Comparison of platelet storage in PL146 and PL732 plastic packs: preliminary in vitro studies.

This paper is a preliminary report of in vitro studies comparing platelet storage in the new polyolefin PL732 packs with the present polyvinyl PL146 packs. The parameters used to assess platelet viability in these studies were the recovery from the hypotonic stress test (HST) and the pH. The effect of the mass of concentrate was assessed by preparing 20 g, 35 g and 50 g packs. The method of agitation was tested comparing a vertical rotator with a flat-bed, rocking agitator. In all the subgroups the PL732 packs fared better than the PL146 packs in terms of HST recovery and pH. The 35 g and 50 g packs were statistically inseparable but the 20 g packs were significantly worse both in PL732 and PL146. The vertical rotator augmented the beneficial effects of the PL732 plastic especially in terms of pH. The 35 g and 50 g packs in PL732 on a vertical rotator gave results after 5 days storage at 22 degrees C which were vastly superior (p less than or equal to 0.001) to the 35 g and 50 g packs in PL146 after only three days storage. Thus it would appear that the use of PL732 packs might enable the storage life of platelet concentrates to be increased to five days. Further in vivo studies are to be undertaken to ensure these in vitro improvements benefit the patient.

Blood Platelets↗