PubMed Health⌕ Search

Biomedical subjects

R C Peterson

Publications and source records attributed to R C Peterson.

At least 19 recordsLinked to original sources
PubMed1988

Expression and processing of recombinant human terminal transferase in the baculovirus system.

Overproduction of human terminal transferase protein has now been accomplished by cloning the coding sequence of human terminal transferase into a baculovirus, where the expression of terminal transferase is under the control of the polyhedrin protein promoter. Two constructs were made, one producing a protein containing the entire terminal transferase fused to 12 amino acids from the NH2 terminus of the polyhedrin protein, and the other producing 58-kDa human terminal transferase. The terminal transferase levels expressed in cells infected with either recombinant baculovirus are around 10,000 units/10(7) cells at 48 h postinfection, about 200-fold greater than levels expressed in thymus and cultured lymphoblastoid cells. The chimeric polyhedrin/human terminal transferase protein produced in the infected insect cells has a molecular weight of about 60,000 while the nonfused recombinant human terminal transferase is identical in molecular weight to that present in human lymphoblastoid cells. Both forms of recombinant terminal transferase show immunological and enzymatic activity. When infected cells are pulse-labeled with [35S] methionine at 42-45 h postinfection, about 10% of newly synthesized protein is terminal transferase. Both forms of terminal transferase are phosphorylated in recombinant virus-infected cells as demonstrated by pulse-labeling infected cells with 32P-inorganic phosphate and isolation of labeled terminal transferase peptides by immunoprecipitation.

Animals↗
PubMed1988

Nitrous oxide and human state-dependent memory.

State-dependent effects of nitrous oxide on human memory were examined by administering serial and paired-associate learning tasks to subjects receiving 20 and 30% nitrous oxide or placebo. Nitrous oxide in 30% concentration impaired learning of both tasks. In addition, it produced an atypical form of asymmetric state-dependent memory; subjects who learned while receiving placebo and recalled while receiving nitrous oxide displayed the worst recall.

Adult↗
PubMed1988

Prediction of the frequencies of restriction endonuclease recognition sequences using di- and mononucleotide frequencies.

The calculation of probabilities of nucleotide sequences from the frequencies of dinucleotides is described. The dinucleotide and mononucleotide frequencies used can be obtained from nearest neighbor analysis or from databank sequences. If dinucleotide and mononucleotide frequencies from nearest neighbor analysis are used, probabilities for oligonucleotides can be calculated for genomes in which there is little or no sequence data. Within a given genome, a broad range of probabilities for hexanucleotide palindromes with the same base composition is predicted and shown (14).

DNA Restriction Enzymes↗
PubMed1987

Sequence and transcription of tRNAVal gene from Xenopus laevis.

A DNA fraction enriched in tRNA genes has been prepared by CsCl density gradient centrifugation of Xenopus laevis DNA in the presence of actinomycin D. This DNA fraction was cut with the restriction endonuclease EcoRI and the fragments 800-900 base pairs in size were cloned into the plasmid pBR325. Recombinant DNAs were screened by hybridization to labeled tRNA and for the ability to support transcription in vitro. The entire sequence of one fragment was determined by sequencing the ends of an overlapping set of deletion fragments. A sequence homologous to tRNAVal from mammalian sources was found in this fragment and it was shown that this sequence corresponds to the region of the fragment that is transcribed. The cloned fragment was also transcribed in vivo after injection into X. laevis oocytes. The RNA that was synthesized in the oocytes was digested with ribonuclease T1 and the oligonucleotides were separated to produce a two-dimensional fingerprint. The results of the analysis of the oligonucleotides are consistent with the sequence determined for the tRNAVal gene. The X. laevis genome has 200-250 copies of the 892 base pair EcoRI fragment and additional copies of a 4100 base pair EcoRI fragment that each contain a tRNAVal gene. Digestion of X. laevis DNA with several other restriction endonucleases reveals that the cloned fragment that contains the tRNAVal gene is part of a longer sequence element that is tandemly repeated in the genome.

Animals↗
PubMed1985

Expression of human terminal deoxynucleotidyl transferase in Escherichia coli.

A cloned DNA fragment related to pT17 containing a partial cDNA sequence of human terminal deoxynucleotidyl transferase was used as a probe to screen for the full length cDNA sequence of the enzyme in a lambda gt11 library constructed from human lymphoblastoid KM-3 cDNA. A recombinant containing a 2068-base pair insert was isolated and recloned into the EcoRI site of the sequencing plasmic pUC-8 as two subclones, pT711 and pT106. DNA sequencing and hybridization studies showed that pT711 contains the pT17 sequence and an additional 172 upstream nucleotides. pT711 represents the coding sequence for the carboxyl half of the terminal transferase protein. pT106, containing a 965-base pair insert, hybridizes to the same mRNA as pT711 on Northern blots and contains an open reading frame that is in phase with the reading frame of the insert in pT711. Amino acid sequencing of the 58-kDa peptide of the calf thymus terminal transferase failed, indicating that the N terminus is blocked. N-Terminal sequencing of a 56-kDa form of the protein produced 24 amino acids corresponding to the translated human cDNA coding sequence starting at residue 398 of the insert in pT106 with 83% homology between bovine and human sequence. The initiation codon is assigned to an ATG sequence at nucleotide 329 of the insert in pT106. Comparison of the translated human terminal transferase sequence with peptides from the calf thymus enzyme showed that the homology between the human and bovine enzyme is better than 90% among 263 amino acids determined. The coding sequences in pT106 and pT711 were recloned into an expression plasmid pUC-19 downstream from the lac promoter and in phase with the coding sequence of the lac Z gene. Lysates of bacteria carrying the reconstructed coding sequence of human terminal transferase contain a fused protein of 60 kDa that reacts with rabbit antibody to terminal transferase on immunoblots and exhibits enzyme activity. Isolation of this fused protein from bacterial lysates with mouse monoclonal antibody to human terminal transferase produces the expected protein of 60 kDa.

Amino Acid Sequence↗
PubMed1985

Chromosome localization of the gene for human terminal deoxynucleotidyltransferase to region 10q23-q25.

Complementary DNA clones representing the 3' half, the 5' half, and the entire coding region of the human terminal deoxynucleotidyltransferase gene (TdT; DNA nucleotidylexotransferase, nucleosidetriphosphate: DNA deoxynucleotidylexotransferase, EC 2.7.7.31) were used to screen a panel of mouse X human somatic cell hybrid DNAs to determine the chromosomal location of the human TdT gene. The results of the Southern transfer analysis of hybrid DNAs indicate that the gene for TdT is located on human chromosome 10. The in situ hybridization technique was then used to further localize the gene for TdT to region q23-q25 of human chromosome 10.

Chromosome Mapping↗
PubMed1984

Molecular cloning of human terminal deoxynucleotidyltransferase.

A cDNA of the human terminal deoxynucleotidyltransferase (TdT; "terminal transferase," EC 2.7.7.31) was isolated from a human lymphoblastoid cell cDNA library in lambda gt 11 by using immunological procedures. Four inserts containing 723 to 939 base pairs were recloned in pBR322 for hybridization and preliminary sequence studies. mRNA selected by hybridization to recombinant DNA was translated to a 58-kDa peptide that specifically immunoprecipitated with rabbit antibodies to calf terminal transferase and mouse monoclonal antibody to human terminal transferase. Blot hybridization of total poly(A)+ RNA from KM3 (TdT+) cells with nick-translated pBR322 recombinant DNA detected a message of about 2000 nucleotides, sufficient to code for the 580 amino acids in the protein. mRNA from terminal transferase- cells gave no signal in hybrid selection or RNA blot hybridization. The complete sequence of the 939-base-pair insert sequence was obtained from deletions cloned in pUC8. The DNA sequence contains an open reading frame coding for 238 amino acids, about 40% of the protein. Three peptides isolated by HPLC from tryptic digests of succinylated 58-kDa calf thymus terminal transferase were sequenced, providing 20, 18, and 22 residues of peptide sequence. A search of the translated sequence of the 939-base-pair insert shows three regions beginning after arginine that have greater than 90% homology with the sequence determined from the calf thymus terminal transferase peptides. These results provide unambiguous evidence that the human terminal transferase sequence has been cloned.

Amino Acid Sequence↗
PubMed1984

In utero exposure of bovine fetuses to polychlorinated biphenyls.

Pregnant mature beef cows more than 6 mo from parturition were fed whole plant corn silage from either a silo (contaminated) that had been coated with a plastic containing polychlorinated biphenyls (Aroclor 1254) or from a silo (clean) that had not been coated with the plastic. In addition, a third group of cows was fed silage from the clean silo plus 200 mg Aroclor 1254 per head daily (added polychlorinated biphenyls). After 30 days on treatment, one cow from each of the three treatments had her fetus removed by Caesarean section for assay of liver, thyroid, and fat for polychlorinated biphenyls content. Tissue content of polychlorinated biphenyls for fetuses from cows fed clean silage, contaminated silage, or added polychlorinated biphenyls was (microgram/g): liver, 3.6, 4.7, and 54.1; thyroid, 2.3, 19.4, and 121.1; fat, .65, 18.1, and 130.6, indicating polychlorinated biphenyls cross the placenta readily. Cow milk (colostrum) contents of polychlorinated biphenyls on the 1st day following parturition for the three respective treatments were .54, 8.5, and 96.4 micrograms/g (clean silage, contaminated silage, and added polychlorinated biphenyls). Fetuses taken from cows that had been removed from polychlorinated biphenyl exposure for 6 mo reflected previous treatments of dams by increased fetal fat stores of polychlorinated biphenyls.

Adipose Tissue↗
PubMed1981

Acetaminophen overdose. 662 cases with evaluation of oral acetylcysteine treatment.

Six hundred sixty-two consecutive patients with acetaminophen overdoses were evaluated. Those at risk on the basis of their acetaminophen blood levels, as plotted on the study nomogram, were treated with oral acetylcysteine. Statistically significant differences in severity of hepatic toxicity were observed between patients treated within 16 hours after ingestion and those treated between 16 and 24 hours after ingestion. No deaths occurred among patients treated within 24 hours of ingestion, except for one patient who was an alleged gunshot homicide. Seven percent of patients with plasma acetaminophen levels in the potentially toxic range and treated with acetylcysteine within ten hours of ingestion showed transient SGOT level elevations, whereas 29% of those treated between ten and 16 hours after ingestion and 62% of those treated between 16 and 24 hours after ingestion showed such transient toxicity. No consistent difference in hepatotoxicity could be demonstrated between those patients with a history of chronic alcohol use and those patients with no history of chronic alcohol use. Acute alcohol use resulted in less severe toxic reactions than in those patients without acute alcohol use.

Acetaminophen↗
PubMed1981

Dietary Aroclor 1254 in the milk fat of lactating beef cattle.

Excretion in milk fat of Aroclor 1254 (a mixture of polychlorinated biphenyl) by mature beef cows (Hereford and Hereford cross) was studied. Three groups of 6 cows each were fed primarily a corn silage diet characterized by 1) clean silage (stored in an uncontaminated silo), 2) silage stored in a silo coated with a sealant containing Aroclor 1254, and 3) clean silage to which 200 mg Aroclor 1254 per head daily was added (approximately 2 to 3 mg/kg body weight per day). Treatments were started approximately 3 mo prior to parturition and extended 1 mo after parturition, at which time treatments were discontinued, and cows and nursing calves were placed on pasture. Milk was sampled in the period between parturition and 132 days after discontinuance of treatments. Fat from the milk of cows fed silage from the silo which had not been sealed with the Aroclor 1254 product contained .69 to 1.59 ppm Aroclor 1254 throughout the 164-day lactation. Fat from cows fed silage from the silo treated with the Aroclor 1254 sealant contained more than ten times as much Aroclor 1254 (15.7 to 18.4 ppm) for 32 days as compared with the controls and then dropped to one-half that figure through the 164th day. Fat from the milk of cows fed 200 mg Aroclor 1254 per day contained from 119 to 150 ppm through the first 32 days and then dropped to 39 to 51 ppm through day 164.

Animals↗
PubMed1980

Characterization of two xenopus somatic 5S DNAs and one minor oocyte-specific 5S DNA.

The somatic 5S DNA from X. borealis (Xbs 5S DNA) and X. laevis (Xis 5S DNA) and a minor oocyte-specific 5S DNA from X. laevis (Xit 5S DNA) have been purified, and individual repeating units have been cloned and sequenced. The two somatic 5S DNAs differ from the major oocyte 5S DNAs in having GC-rich spacers, homogeneous repeat lengths and no "pseudogenes." The somatic 5S DNAs from the two species have similar spacer sequences with differences due to single base changes and insertions/deletions. The spacer of the minor oocyte-specific 5S DNA (Xit) has the AT-rich sequence characteristic of the major oocyte 5S DNAs from X. laevis and X. borealis, and contains one duplication that has diverged approximately 40%. Like the somatic 5S DNAs, Xit 5S DNA has a homogeneous length repeat and a unique nucleotide sequence in its spacer. The presence of variable-length spacer regions in a multigene family correlates with variables numbers of a simple sequence in the spacer regions.

Animals↗
PubMed1980

Marijuana and health: 1980.

In this eighth edition of the Marihuana and Health Report several areas of recent developments in marijuana research are highlighted together with a summary of the scientific research accumulated through the end of 1979 concerning the drug's possible health implications.

Alcohol Drinking↗
PubMed1977

Binding specificity of the juvenile hormone carrier protein from the hemolymph of the tobacco hornworm Manduca sexta Johannson (Lepidoptera: Sphingidae).

A series of analogues of insect juvenile hormone (four geometric isomers of methyl epoxyfarnesenate, several para-substituted epoxygeranyl phenyl ethers, and epoxyfarnesol and its acetate and haloacetate derivatives) was prepared to investigate the binding specificity of the hemolymph juvenile hormone binding protein from the tobacco hornworm Manduct sexta. The relative binding affinities were determined by a competition assay against radiolabeled methyl (E,E)-3,11-dimethyl-7-ethyl-cis-10,11-epoxytrideca-2,6-dienoate (JH I). The ratio of dissociation constants was estimated by plotting competitor data according to a linear transformation of the dissociation equations describing competition of two ligands for a binding protein. The importance of the geometry of the sesquiterpene hydrocarbon chain is indicated by the fact that the binding affinity is decreased as Z (cis) double bonds are substituted for E (trans) double bonds in the methyl epoxyfarnesenate series; the unepoxidized analogues do not bind. A carboxylic ester function is important although its orientation can be reversed, as indicated by the good binding of epoxyfarnesyl acetate. In the monoterpene series, methyl epoxygeranoate shows no affinity for the binding protein, but substitution of a phenyl or p-carbomethoxyphenyl ether for the ester function imparts a low, but significant affinity. These data taken together with earlier results indicate that the binding site for juvenile hormone in the hemolymph binding protein is characterized by a sterically defined hydrophobic region with polar sites that recognize the epoxide and the ester functions.

Animals↗
PubMed1977

Selenium in milk from feeding small supplements.

Supplements of 0, 1, 2, or 5 mg of selenium from sodium selenite fed per cow daily from 90 days prepartum through approximately 6 mo of lactation had no significant effect on selenium in milk of Hereford cows. Selenium in milk was assayed 2 to 3 days postpartum (average of .014 to .023 ppm) and approximately 3 mo post parturition (average of .016 to .021 ppm). The basal diet consisted of medium quality grass-legume hay (.069 mg/kg), ad libitum liquid supplement (.152 mg/kg), and 1.36 kg shelled corn (.018 mg/kg) starting in early lactation. Treatments of selenium were administered via free-choice liquid supplement.

Animals↗
PubMed1976

Purification and characterization of the carrier protein for juvenile hormone from the hemolymph of the tobacco hornworm Manduca sexta Johannson (Lepidoptera: Sphingidae).

The larval hemolymph of the tobacco hornworm, Manduca sexta, contains a carrier protein that binds specifically and with high affinity the juvenile hormone, an important regulator of insect development. This protein serves to transport the hormone and to protect it from the action of degradative enzymes during early larval stages. Using hemolymph from the last larval stage, we have isolated a pure carrier protein using acetone precipitation, gel filtration, ion exchange chromatography, and preparative isoelectric focusing. Gel filtration, polyacrylamide gel electrophoresis in sodium dodecyl sulfate, and equilibrium ultracentrifugation established that the carrier protein is a single chain polypeptide of approximately 28,000 daltons. The amino acid composition is unexceptional, and no evidence for hexosamine has been obtained. An ion exchange filter disc assay method was used to determine the formation of the complex between the carrier protein and isotopically labeled juvenile hormone. With this technique it was shown that each carrier protein binds one hormone molecule with a dissociation constant of 4.4 +/- 0.2 X 10(-7) M at 0 degrees.

Amino Acids↗