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Biomedical subjects

J Marks

Publications and source records attributed to J Marks.

At least 127 records · Page 7Linked to original sources
PubMed1990

Multiple breakpoint method for measuring effect of antibiotics on endocarditis strains of streptococci.

The activity of penicillin alone and combined with aminoglycoside on endocarditis strains of streptococci was examined. Good assay reproducibility was obtained by the use of logarithmic phase cultures standardised by opacity, careful inoculation of well-plates, removal of antibiotic by membrane transfer and incubating survival counts in hydrogen plus carbon dioxide. The use of 10-fold intervals for penicillin concentration simplified assay design without loss of efficiency.

Drug Therapy, Combination↗
PubMed1989

Anomalous and selective DNA mutations of the Old World monkey alpha-globin genes.

It has been a widely accepted hypothesis that the molecular clock slows down during evolution of higher primates. By molecular cloning and nucleotide sequence comparison of a rhesus macaque alpha-globin gene to its homologs in man, orangutan, olive baboon, and other mammals, we demonstrate a burst of evolution of the baboon alpha-globin gene since its separation from the rhesus macaque. This mutation burst has occurred only at the nonsynonymous sites but not the synonymous sites. Its magnitude is at least 10-fold higher than the synonymous substitution rates in higher primates and as high as the synonymous substitution rates of the rodent lineage. On the contrary, the rate of synonymous site substitutions in the alpha-globin genes of either the rhesus macaque or the olive baboon is several times slower than that of human. Our data demonstrate an anomalous exception to the slow rates of molecular evolution in higher primates and provide strong evidence for a recently accelerated evolution of a primate globin gene under an as yet unknown selective force(s).

Amino Acid Sequence↗
PubMed1989

Relapse rates in moderately severe chronic psoriasis treated with cyclosporin A.

Seventeen patients with chronic psoriasis were given cyclosporin A (CsA) 5 mg/kg per day. Twelve patients cleared within 3 months and their relapse rate, 41% at 6 months, was not significantly different from that previously reported with dithranol or PUVA. This pilot study also suggests that continuing CsA for up to 4 weeks after clinical clearance confers no advantage with regard to relapse. Significant adverse effects on renal function and blood pressure did not occur.

Adult↗
PubMed1989

The safety of the vitamins: an overview.

On the basis of the reviewed information it is considered that the vitamins can be divided into two broad categories. a) Those with a safety level at least 50-100 times the RDA and no clear indication of serious adverse reactions above the level. This level should be adequate to match any required pharmacological dose, and these vitamins should be regarded as safe for elevated dose use, not necessarily controlled by doctors. b) Those with a safety ratio of about 10 times, often influenced by the health status of the individual or those with serious irreversible adverse reactions. These vitamins (retinol, calciferol, pyridoxine) can be used safely at an RDA level but should only be administered at higher dosage under medical supervision to avoid dose escalation.

Humans↗
PubMed1988

Structure and expression of the human theta 1 globin gene.

The recently identified theta-globin gene subfamily consists of the theta 1-globin gene located downstream from the alpha 1-globin gene, and several other members including at least one truncated, processed pseudogene psi theta 2 (refs 1,6). Unlike the theta 1-globin genes of the rabbit and galago, the structure of these genes in the orangutan and baboon and their flanking regions show no apparent defects that would prevent their expression. Both theta 1-globin genes are split into three exons with the potential to code for a polypeptide of length 141 amino acids. Besides differing by 26% in replacement-site substitutions, the theta 1 and alpha 1-globin genes of the orangutan and baboon also differ in their promoter structures, in the use of TGA versus TAA as the termination codon, and in the use of AGTAAA versus AATAAA as the polyadenylation signal. In contrast, the two theta 1-globin genes from primates only differ by 1.7% in the replacement-site substitutions. Here we present the complete DNA sequence of a cloned theta 1-globin gene of humans, and show that it contains no apparent defects that would abolish its expression. Furthermore, by primer extension of single-stranded oligonucleotide probes, we show that the theta 1-globin gene of humans is transcribed in an erythroleukemia cell line K562. Three messenger RNA species were detected, with 5'-ends mapping to approximately 70 base pairs (bp) downstream from a TATA promoter sequence, at 8 bp downstream from a GGGCGG promoter sequence and at 40 bp upstream from the ATG inititrion codon, respectively. Haemin treatment of the K562 cells slightly enhances the level of the longest theta 1-transcript. Our results provide strong evidence that the theta 1-globin gene of humans is transcriptionally active in cells of erythroid origin, and suggests the presence of a functional theta 1-polypeptide in specific cells, possibly those of early erythroid tissue.

Amino Acid Sequence↗