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Biomedical subjects

S Anderson

Publications and source records attributed to S Anderson.

At least 559 records · Page 31Linked to original sources
PubMed1981

Effect of antihypertensive therapy on plasma catecholamines in renal failure patients.

The influence of antihypertensive therapy on plasma norepinephrine (NE) was examined in 58 patients with moderate chronic renal failure (CRF). Six normotensive patients not receiving antihypertensive medicines (mean serum creatinine 2.4 +/-.2 mg/dl) had a modest but significant increase in NE compared to normals in both supine (230 vs. 173 pg/ml, P greater than .05) and upright (482 vs. 377 pg/ml, P less than .05) positions. A striking increase in NE (supine 673 +/- 55, P less than .001; upright 1089 +/- 88 pg/ml, P less than .001) was observed in 34 CRF patients receiving antihypertensive regimens containing diuretic, beta-blocker, or vasodilator drugs either individually or in combination. Vasodilator therapy was associated with the highest levels of NE. In 17 further CRF patients receiving the sympathetic suppressants clonidine or methyldopa in addition to other medicines, NE values were similar to untreated, normotensive patients (supine NE 254 +/- 40 pg/ml; upright NE 474 +/- 61 pg/ml). The age, degree of renal impairment, plasma renin activity, and number and dosage of antihypertensive medicines did not account for these differences in NE. The results suggests that NE levels are modestly increased in normotensive, untreated CRF patients, but are dramatically increased by antihypertensive therapy, particularly vasodilator therapy. Clonidine or methyldopa therapy, however, is associated with significantly lower NE values in these patients despite the concomitant use of vasodilator agents.

Antihypertensive Agents↗
PubMed1980

Distinctive sequence of human mitochondrial ribosomal RNA genes.

The nucleotide sequence spanning the ribosomal RNA (rRNA) genes of cloned human mitochondrial DNA reveals an extremely compact genome organization wherein the putative tRNA genes are probably 'butt-jointed' around the two rRNA genes. The sequences of the rRNA genes are significantly homologous in some regions to eukaryotic and prokaryotic sequences, but distinctive; the tRNA genes also have unusual nucleotide sequences. It seems that human mitochondria did not originate from recognizable relatives of present day organisms.

Base Sequence↗
PubMed1980

Activation of rabbit muscle phosphofructokinase by F-actin and reconstituted thin filaments.

Striking effects of F-actin and the reconstituted thin filament of muscle on the catalytic activity of rabbit muscle phosphofructokinase are demonstrated through direct measurements of enzymatic activity by using the pH stat. The addition of F-actin to solutions of phosphofructokinase at low ionic strength (10 mM KCl and 5 mM MgCl2) partially reverses the inhibition of the enzyme seen at high ATP concentrations and increases the apparent affinity of the enzyme for fructose 6-phosphate with slight effect on Vmax. F-Actin augments the activation of the enzyme obtained with AMP and partially counters the inhibition obtained with citrate. The maximum effect in the reversal of ATP inhibition is about the same for combinations of either F-actin or the thin filament with AMP as it is for AMP alone. In general, the effect of F-actin on the catalytic activity of phosphofructokinase is larger than that of the thin filament. The activation of phosphofructokinase by F-actin persists at physiological ionic strength.

Actins↗
PubMed1980

A short primer for sequencing DNA cloned in the single-stranded phage vector M13mp2.

In this paper we describe the synthesis and cloning of a short segment of DNA complementary to the region immediately adjacent to the EcoRI insertion site in the single-stranded bacteriophage vector M13mp2. This segment is useful as a "universal" primer for DNA sequencing by the dideoxynucleotide chain termination method; the template can be any DNA species cloned in M13mp2 or its derivatives. The primer has been cloned into the tetracycline resistance gene of plasmid pBR322 as one strand of a 26 bp EcoRI/BamHI fragment. This fragment may be readily prepared from an EcoRI + BamHI restriction digest of the parent plasmid (designated pSP14) by a simple size fractionation.

Base Sequence↗
PubMed1980

Chloral hydrate sedation as a substitute for examination under anesthesia in pediatric ophthalmology.

We examined more than 300 children as outpatients with orally administered chloral hydrate sedation during the past three years; 175 of them have been examined in the last year. Without chloral hydrate sedation, examination under anesthesia would have been necessary or the results would have been less than satisfactory. Orally administered chloral hydrate has a wide margin of safety and is most appropriate for office or clinic use. It may also allow accurate measurement of the intraocular pressure in infantile glaucoma.

Administration, Oral↗
PubMed1980

The genetic code in bovine mitochondria: sequence of genes for the cytochrome oxidase subunit II and two tRNAs.

Bovine-heart mitochondrial DNA from a single animal was isolated and fragments representative of the entire genome cloned into multicopy plasmid vectors to facilitate determination of its complete nucleotide sequence. We present here the sequence of the region covering the gene for cytochrome oxidase subunit II. Comparison of this sequence with the amino acid sequence of the homologous beef-heart protein has enabled the determination of most of the bovine mitochondrial genetic code. The code differs from the "universal" genetic code in that UGA codes for tryptophan and not termination, and AUA codes for methionine and not isoleucine. The only codon family not represented is the AGA/AGG pair normally used for arginine; evidence from other genes suggests that these code for termination in bovine mitochondria. The sequence presented also includes the adjacent tRNAAsp and tRNALys genes. The tRNAAsp gene is separated by one nucleotide from the 5' end of the COII gene and only three bases separate the 3' end of this gene and the adjacent tRNALys gene. This highly compact gene organisation is very similar to that found in the corresponding region of the human mitochondrial genome and the gene arrangement is identical. The structure of the respective bovine and human tRNAs vary primarily the "D-" and "T psi C-loops".

Animals↗
PubMed1980

Different pattern of codon recognition by mammalian mitochondrial tRNAs.

Analysis of an almost complete mammalian mitochondrial DNA sequence has identified 23 possible tRNA genes and we speculate here that these are sufficient to translate all the codons of the mitochondrial genetic code. This number is much smaller than the minimum of 31 required by the wobble hypothesis. For each of the eight genetic code boxes with four codons for one amino acid we find a single specific tRNA gene with T in the first (wobble) position of the anticodon. We suggest that these tRNAs with U in the wobble position can recognize all four codons in these genetic code boxes either by a "two out of three" base interaction or by U.N wobble.

Animals↗
PubMed1980

Transplacental diffusion of ethanol under steady state conditions.

The placental clearances of ethanol and antipyrine, uterine and umbilical blood flows (ml/min) were measured in six chronic sheep preparations. The two substances were infused simultaneously at constant rate into the fetal inferior vena cava. In the steady state, blood samples were obtained from the fetal abdominal aorta, common umbilical vein, maternal uterine vein and maternal femoral artery and analysed for the blood concentrations of ethanol and antipyrine. The clearance of ethanol (CE) was related to uterine (F) and umbilical (f) blood flows according to the regression equation: CE = -26 + 0.88 (F x f)/(F + f), (r = 0.987). The ethanol/antipyrine clearance ratio ranged between 1.21 and 0.97 (mean 1.07, 95% confidence limits 1.01-1.14) These data support the hypothesis that the placental clearance of ethanol is primarily flow-limited.

Animals↗
PubMed1980

A broader training for medical receptionists.

A course for 40 medical receptionists working in general practice was arranged at a local postgraduate centre. The curriculum was divided into two sections. The first dealt with the traditional, factual side of medical reception work and the second was concerned with the human behaviour aspect of a receptionist's work. It seems that there was some benefit to the receptionists from their experience of both aspects of this course.

Curriculum↗
PubMed1979

Metabolism of Okazaki fragments during simian virus 40 DNA replication.

Essentially all of the Okazaki fragments on replicating Simian virus 40 (SV40)DNA could be grouped into one of three classes. Class I Okazaki fragments (about 20%) were separated from longer nascent DNA chains by a single phosphodiester bond interruption (nick) and were quantitatively identified by treating purified replicating DNA with Escherichia coli DNA ligase and then measuring the fraction of Okazaki fragments joined to longer nascent DNA chains. Similarly, class II Okazaki fragments (about 30%) were separated by a region of single-stranded DNA template (gap) that could be filled and sealed by T4 DNA polymerase plus E. coli DNA ligase, and class III fragments (about 50%) were separated by RNA primers that could be removed with E. coli DNA olymerase I, allowing the fragments to be joined with E. coli DNA ligase. These results were obtained with replicating SV40 DNA that had been briefly labeled with radioactive precursors in either intact cells or isolated nuclei. When isolated nuclei were further incubated in the presence of cytosol, all of the Okazaki fragments were converted into longer DNA strands as expected for intermediates in DNA synthesis. However, when washed nuclei were incubated in the abscence of cytosol, both class I and class II Okazaki fragments accumulated despite the excision of RNA primers: class III Okazaki fragments and RNA-DNA covalent linkages both disappeared at similar rates. These data demonstrate the existence of RNA primers in whole cells as well as in isolated nuclei, and identify a unique gap-filling step that is not simply an extension of the DNA chain elongation process concomitant with the excision of RNA primers. One or more factos found in cytosol, in addition to DNA polymerase alpha, are specifically involved in the gap-filling and ligation steps. The sizes of mature Okazaki fragments (class I) and Okazaki fragments whose synthesis was completed by T4 DNA polymerase were measured by gel electrophoresis and found to be broadly distributed between 40 and 290 nucleotides with an average length of 135 nucleotides. Since 80% and 90% of the Okazaments does not occur at uniformly spaced intervals along the DNA template. During the excision of RNA primers, nascent DNA chains with a single ribonucleotide covalently attached to the 5' terminus were identified as transient intermediates. These intermediates accumulated during excision of RNA primers in the presence of adenine 9-beta-D-arabinoside 5'-triphosphate, and those Okazaki fragments blocked by RNA primers (class III) were found to have originated the farthest from the 5' ends of long nascent DNA strands. Thus, RNA primers appear to be excised in two steps with the second step, removal of the final ribonucleotide, being stimulated by concomitant DNA synthesis. These and other data were used to construct a comprehensive metabolic pathway for the initiation, elongation, and maturation of Okazaki fragments at mammalian DNA replication forks.

DNA Ligases↗
PubMed1979

Maturation of replicating simian virus 40 DNA molecules in isolated nuclei by continued bidirectional replication to the normal termination region.

Mature SV40 DNA synthesized for different periods of time either in isolated nuclei or in intact cells was highly purified and then digested with restriction endonucleases in order to relate the time of synthesis of newly replicated viral DNA to its location in the genome. Replication in nuclei supplemented with a cytosol fraction from uninfected cells was a faithful continuation of the bidirectional process observed in intact cells, but did not exhibit significant initiation of new replicons. SV40 DNA replication in cells at 37 degrees C proceeded at about 145 nucleotides/min per replication fork. In the absence of cytosol, when DNA synthesis was limited and joining of Okazaki fragments was retarded, bidirectional SV40 DNA replication continued into the normal region where separation yeilded circular duplex DNA molecules containing one or more interruptions in the nascent DNA strands. In the presence of cytosol, this type of viral DNA was shown to be a precursor of covalently closed, superhelical SV40 DNA, the mature from of viral DNA.

Animals↗
PubMed1979

Effects in normal subjects of long-term administration of azosemide.

Azosemide is a new loop diuretic which has been shown to affect solute transport proximal to the diluting segment. We assessed the effects of chronic administration of azosemide in normal subjects on low and normal salt diets. In both, there was compensatory renin release and aldosterone secretion, but the subjects on the low sodium diet developed striking hyperuricemia and metabolic alkalosis and were symptomatic, whereas those on the normal diet compensated to the extent that there were only minor changes.

Diet, Sodium-Restricted↗