Oligonucleotides containing the 5' termini of adenovirus 2 mRNA are selectively retained on columns of dihydroxyboryl cellulose. When total late adenovirus 2 mRNA was treated with RNAase T1, a single 5' terminal oligonucleotide was isolated, although in several states of methylation. This oligonucleotide has the general structure m7G5'ppp5' AmCmU(C4,U3)G. Since at least twelve individual species of mRNA must be present late after infection, this finding was unexpected and its significance is discussed.

Adenoviridae↗

PubMed1977

An amazing sequence arrangement at the 5' ends of adenovirus 2 messenger RNA.

The 5' terminal sequences of several adenovirus 2 (Ad2) mRNAs, isolated late in infection, are complementary to sequences within the Ad2 genome which are remote from the DNA from which the main coding sequence of each mRNA is transcribed. This has been observed by forming RNA displacement loops (R loops) between Ad2 DNA and unfractionated polysomal RNA from infected cells. The 5' terminal sequences of mRNAs in R loops, variously located between positions 36 and 92, form complex secondary hybrids with single-stranded DNA from restriction endonuclease fragments containing sequences to the left of position 36 on the Ad2 genome. The structures visualized in the electron microscope show that short sequences coded at map positions 16.6, 19.6 and 26.6 on the R strand are joined to form a leader sequence of 150-200 nucleotides at the 5' end of many late mRNAs. A late mRNA which maps to the left of position 16.6 shows a different pattern of second site hybridization. It contains sequences from 4.9-6.0 linked directly to those from 9.6-10.9. These findings imply a new mechanism for the biosynthesis of Ad2 mRNA in mammalian cells.

Adenoviruses, Human↗

PubMed1977

Oxygen therapy and hyaline membrane disease: the effect of hyperoxia on pulmonary superoxide dismutase activity and the mediating role of plasma or serum.

In vitro and in vivo hyperoxic exposure of the lungs of normal immature animals resulted in a rapid increase of pulmonary superoxide dismutase activity. The increase of pulmonary SOD activity with in vitro hyperoxic exposure requires the presence of plasma or serum in the incubation medium. Twenty-three out of 26 plasma samples from premature infants without hyaline membrane disease were found to support the hyperoxic increaase of pulmonary SOD activity, whereas only five of 15 plasma samples from infants with HMD were effective. A defective plasma-lung interaction in infants with HMD may result in an inability to increase pulmonary levels of this presumed protective enzyme during hyperoxic therapy.

Animals↗

PubMed1977

Age-related differences in salicylamide and acetaminophen conjugation in man.

Following a concomitant oral dose of salicylamide and acetaminophen (5 mg/kg of each) the urinary excretion of glucuronide and sulfate conjugates of the drugs were followed in children (ages seven to ten years) and adults. No significant difference were observed between the two age groups in the half-lives for appearance of salicylamide conjugates in urine. Age-related changes in the metabolic pathways, however, were observed. The mean percentage of dose excreted as salicylamide sulfate was significantly higher in children (78%) than in adults (36%). In contrast, salicylamide glucuronide was the major excretory product in adults. Similar age-related differences were observed for acetaminophen conjugation. Pharmacokinetic analysis indicated that the deficiency in glucuronide conjugation of these drugs in children is accompanied by a higher rate of sulfate formation.

Acetaminophen↗

PubMed1977

A site-specific single-strand endonuclease from the eukaryote Chlamydomonas.

We have found a unique deoxyribonuclease in extracts of the eukaryotic green alga Chlamydomonas. When incubated with viral DNA from adenovirus-2, this enzyme produces discrete fragments that form bands upon electrophoresis in an agarose gel. Site specificity of the enzymatic cleavage examined by identifying the 5'-terminal nucleotides in cleaved adenovirus-2 DNA and by studies with synthetic polynucleotides of defined sequence, indicates that the initial endonucleolytic cleavage occurs at a site containing a deoxythymidine residue. Electron microscopy of cleaved adenovirus-2 DNA revealed single-strand segments within duplex DNA. We propose that the enzyme acts by making initial site-specific single-strand incisions, followed by subsequent excision on the same strand, producing a gapped duplex molecule; and that double-strand scissions result from limited occurrence of overlapping single-strand gaps on complementary strands.

Base Sequence↗

PubMed1977

Effect of potassium cyanate on carbon monoxide and hypoxic hypoxia-induced lethality.

Pretreatment of mice with potassium cyanate for 15 days resulted in a significant increase in hemoglobin-oxygen affinity (decrease in P 50) and a significant protection against hypoxic hypoxia-induced lethality. However, cyanate pretreatment had no significant effect on carbon monoxide-induced lethality. Oxygen consumption in cyanate-treated mice was significantly lower than in controls in room air but not different in hypoxic environments. Whether the protective effect of cyanate on hypoxic hypoxia-induced lethality is due to the increase in hemoglobin-oxygen affinity or attributable to a non-hemoglobin-related action of cyanate remains unresolved. Regardless, the need exists to reevaluate the current concept that changes in hemoglobin affinity for oxygen correlate with susceptibility to hypoxemic states. In addition, data presented together with previous findings support the concept that carbon monoxide lethality is not solely attributable to a carboxyhemoglobin-induced hypoxemia.

Animals↗

PubMed1977

Effects of gestational age, birth weight, and hypoxemia on pharmacokinetics of amikacin in serum of infants.

The serum pharmacokinetics of amikacin were studied in 36 infants treated for suspected bacterial infection. A prolonged serum half-life was associated with the related variables of birth at an early gestational age, low birth weight, and hypoxemia. A postnatal age effect was not apparent when hypoxemic infants were excluded.

Amikacin↗

PubMed1977

Structure of the inverted terminal repetition of adenovirus type 2 DNA.

Several secondary structure features involving the ends of single strands of adenovirus type 2 DNA have been studied by electron microscopy by both the gene 32-ethidium bromide technique and a modification of the standard formamide-cytochrome c technique. A duplex stem of length 115 +/- 10 nucleotide pairs due to pairing between the two members of the inverted terminal repetition is observed in the single-stranded circles that form upon annealing single-stranded linear molecules. This duplex stem is shown to lie at the ends of the DNA by using several reference markers: (i) a newly discovered secondary structure feature (a loop of length ca. 500 nucleotides with a 20-nucleotide pair duplex stem) that maps 73% of the full length from the left end of the molecule and (ii) a duplex region due to a hybridized restriction fragment. There is also some secondary structure within each end of linear single strands. There is some variation in the morphology of the end strucures, and we propose that these involve base pairing, as in a tRNA clover leaf, rather than an exact single hairpin-type inverted repeat. These observations are consistent with the hypothesis that there is a foldback structure at the 3' ends of the DNA that functions as a primer for the initiation of replication.

Adenoviruses, Human↗

PubMed1977

An epidermal papilloma of the Atlantic salmon I: Epizootiology, pathology and immunology.

Papillomatosis of Atlantic Salmon (Salmo salar) was studied with regard to epizootiology, gross and histologic pathology, and host response. It was found to be a condition of parr in their second summer, but also occasionally of young adult fish (smolts and grilse) which have adapted to salt water. The lesion was plaque-like to papillomatous and consisted of stratified squamous epithelium with supporting stroma. Immunologic findings tended to support histologic observations that the lesion was ultimately sloughed as a result of a cell mediate immune response.

Animals↗

PubMed1977

Hepatic uptake of foreign compounds: influence of acute extrahepatic biliary obstruction.

Extrahepatic cholestasis produced by bile duct ligation decreased the net hepatic uptake of organic anions including sllfobromophthalein, sulfobromophthalein glutathione and phenol-3,6-dibromophthalein disulfonate, and the neutral organic compound, ouabain. The net hepatic uptake of procaine amide ethobromide, an organic cation was not similarly affected. Impairment of net hepatic uptake by bile duct ligation was demonstrated by reduced liver concentration and content of administered compound despite higher plasma concentration. Acute bile duct ligation did not alter the amount of hepatic cytoplasmic anion binding proteins. The impaired net hepatic uptake of sulfobromophthalein in bile duct-ligated rats was reversed by re-establishing bile flow. Deleterious effects of endogenous bile or bile constituents and specific alteration of membrane carrier proteins are considered possible contributing factors to the impaired net hepatic uptake process observed in bile duct-ligated rats.

Animals↗

PubMed1976

A specific endonuclease from Haemophilus haemolyticus.

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Coliphages↗