Search PubMed⌕ Search

Biomedical subjects

L Park

Publications and source records attributed to L Park.

48 records · Page 3Linked to original sources
PubMed1989

Response of the human T-cell leukemia virus type 1 long terminal repeat to cyclic AMP.

The sequences that control transcriptional initiation of the provirus of the human T-cell leukemia virus type 1 (HTLV-1) are shown to be responsive to intracellular levels of cyclic AMP. A heptanucleotide sequence present within the 21-nucleotide repeat sequence that is similar to the cyclic AMP-responsive consensus (CRE) sequence was required for cyclic AMP-mediated increase in gene expression. Although the CRE-like sequences were contained within sequences that were responsive to the virally encoded trans-activator (tax), the evidence presented indicates that the mechanisms of promoter induction by the tax product and cyclic AMP are independent. The implication of cyclic AMP stimulation of HTLV-1 provirus gene expression for long-term persistence of infected T cells and for virus-induced transformation is discussed.

Cell Line↗
PubMed1988

Colony stimulating factor-1 induced growth stimulation of v-fms transformed fibroblasts.

The v-fms oncogene, which is capable of transforming fibroblasts, was derived by recombination of a feline leukemia virus with a cellular gene (c-fms) that encodes the receptor for colony stimulating factor 1 (CSF-1). We examined the capacity of recombinant human CSF-1 (produced in a yeast expression system) to stimulate the growth of v-fms transformed rat fibroblasts. Recombinant human CSF-1 bound to v-fms transformed fibroblasts with high affinity (apparent Kd = 6.0 x 10(-10) M); only non-specific binding was observed on control cells. The number of colonies formed in soft agar by v-fms transformed cells was increased by CSF-1 treatment in a dose-dependent manner; a nine fold increase in the number of colonies was seen in the presence of 10(-8) M CSF-1. CSF-1 did not stimulate the growth of either non-transformed cell lines, a non-transformed cell line that expresses a mutated v-fms protein on the cell surface, or cells transformed by the v-fgr oncogene. The growth stimulating effect of CSF-1 on v-fms transformed cells was also seen in monolayer culture. The v-fms transformed cells treated with CSF-1 had a more refractile, rounded morphology than non-treated cells; no morphology change was observed in CSF-1 treated control cells. CSF-1 treatment also increased both the number and size of foci that arose from fibroblasts following transfection with the v-fms oncogene. These data show that the altered CSF-1 receptor encoded by the v-fms oncogene retains a capacity to bind, and be stimulated by, human CSF-1.

Animals↗
PubMed1987

Dental education.

Explore the source record for details and available documents.

Health Education, Dental↗
PubMed1986

Amidation of joining peptide, a major pro-ACTH/endorphin-derived product peptide.

Based on sequence data, rat and mouse pro-adrenocorticotropin (ACTH)/endorphin could give rise to joining peptide, a short acidic peptide that could terminate with a glutamic acid alpha-amide. Rat and mouse pituitary cells were found to cleave the pro-ACTH/endorphin precursor at an -Arg-Arg- site to produce primarily joining peptide-sized material. The amounts of joining peptide were approximately equimolar to the other major pro-ACTH/endorphin-derived products. Using antisera specific for the COOH-terminal modifications of joining peptide and three analytical approaches which separate amidated from glycine-extended forms of joining peptide, it was found that most of the joining peptide in murine anterior and intermediate pituitary was amidated. Identification of the amidated and glycine-extended forms of joining peptide was confirmed by amino acid analysis of the purified molecules. When anterior pituitary corticotrope tumor cells were grown in culture medium lacking ascorbate, there was no detectable ascorbate in the cells; nevertheless, a significant fraction of the joining peptide produced was alpha-amidated, indicating that production of alpha-amidated product was not totally dependent on ascorbate. The amidation state of the joining peptide produced by mouse corticotrope tumor cells was responsive to added ascorbate. Cells grown in medium containing ascorbic acid at the levels found in plasma concentrated the ascorbate to the levels normally found in pituitary tissue, and nearly all of the joining peptide produced was alpha-amidated. The amidation state of secreted joining peptide mirrored the amidation state of the joining peptide in the cells.

Amides↗
PubMed1986

High level stable expression of human interleukin-2 receptors in mouse cells generates only low affinity interleukin-2 binding sites.

A bovine papilloma virus-derived vector was used to direct the high level expression in mouse C127 cells of three different cDNAs encoding the human interleukin-2 receptor. These were: the previously described cDNA clone isolated from the T-cell lymphoma, HUT-102; a cDNA clone isolated from mitogen-activated, normal peripheral blood T cells; and an altered version of the HUT-102 receptor in which Ser247, believed to be the site of protein kinase C-mediated phosphorylation, has been changed to an Ala residue. Fluorescence-activated cell-sorting using a monoclonal antibody directed against the human IL-2 receptor was used to derive stable lines of C127 cells expressing from 2-6 X 10(6) IL-2 binding sites per cell. However, all of these receptors bound IL-2 with low affinity.

Amino Acid Sequence↗
PubMed1982

Enzymatic repair of pyrimidine dimer-containing DNA. A 5' dimer DNA glycosylase: 3'-apyrimidinic endonuclease mechanism from Micrococcus luteus.

A pyrimidine dimer-DNA glycosylase has been purified 20,000-fold from Micrococcus luteus. The enzyme is a single polypeptide chain with Mr = 18,000 that acts specifically on pyrimidine dimers, preferring those in double-stranded DNA to those in single-stranded DNA. The glycosylase cleaves the 5' residue of a pyrimidine dimer generating an apyrimidinic site and a mixed pyrimidine/pyrimidine nucleotide dimer. Under conditions of substrate excess, dimers containing a 5'-thymine are preferred to those with a 5'-cytosine residue. The glycosylase has an associated apyrimidinic/apurinic (AP) endonuclease that prefers apyrimidinic sites at the site of glycosylase action to either apurinic or apyrimidinic residues. This endonuclease is a Class I AP endonuclease in that it cleaves 3' to the AP site generating a 3'-deoxyribose moiety and a 5'-phosphate.

DNA Glycosylases↗
PubMed1982

Neuropathic vesicourethral dysfunction in children. A trial comparing clean intermittent catheterisation with manual expression combined with drug treatment.

Forty-three children with overt neurological disease and neuropathic vesicourethral dysfunction were entered into a trial comparing clean intermittent catheterisation (CIC) with manual expression combined with drug treatment (non-CIC). The 22 children in the CIC group showed a significantly greater improvement in continence than the 21 children in the non-CIC group (P less than 0.001) without a significant increase in the incidence of urinary tract infections. Neither form of treatment is effective in reducing the risk of deterioration of renal function due to the combination of detrusor-sphincter dyssynergia and vesicoureteric reflux. Neither form of treatment improves continence in the presence of gross sphincter weakness or gross impairment of bladder compliance.

Bethanechol Compounds↗
PubMedDate not supplied

Cloning, sequence and expression of human interleukin-2 receptor.

T lymphocytes, essential for the generation of a normal immune response, require the presence of the lymphokine interleukin-2 (IL-2) in order to proliferate. Cells that respond to IL-2 possess a surface receptor glycoprotein specific for this lymphokine. We have recently purified and chemically characterized the IL-2 receptor from both phytohaemagglutinin-activated human T cells and the human T-cell lymphoma HUT-102 (ref. 5). From the NH2-terminal protein sequence obtained in that study, we have now used synthetic oligonucleotides to probe a complementary DNA library, prepared from HUT-102 messenger RNA, for the presence of cDNA clones that might code for the IL-2 receptor. Two cDNA clones were isolated which had closely related DNA sequences. Interestingly, only one coded for an active receptor when transfected into COS-7 cells. This clone contained a 216-base pair (bp) insert that was not present in the other clone. The insert was flanked by an 8-bp direct repeat reminiscent of a transposable element, and appeared to code for a region of marked structural homology to the NH2-terminal region of the receptor molecule.

Amino Acid Sequence↗
PubMedDate not supplied

Race and child welfare services: past research and future directions.

A review of child welfare research suggests that children of color and their families experience poorer outcomes and receive fewer services than their Caucasian counterparts. The relationship between race and the outcomes of child welfare services is confounded, however, by the relationships among race and other contributors to poor child welfare outcomes. Child welfare researchers should take explicit account of race and ethnicity in designing and carrying out their studies. Service approaches intended to meet the special needs of children of color and their families should be developed and rigorously evaluated.

Black or African American↗