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Biomedical subjects

J M Bailey

Publications and source records attributed to J M Bailey.

At least 199 records · Page 11Linked to original sources
PubMed1979

The binding of an avian myeloblastosis virus basic 12,000 dalton protein to nucleic acids.

The binding of a basic 12,000 dalton protein (p12) from avian myeloblastosis virus to viral RNA and heterologous DNA has been investigated. The binding stoichiometries and constants were determined by an extrinsic fluorescence assay. In both cases each bound p12 molecule occupies four nucleotides and the apparent binding constant is approximately 1 x 10(6) M-1. Binding is non-cooperative and there is no apparent difference in the interaction of p12 with viral RNA or heterologous single-strand DNA. The relative binding constant at various ionic strengths was assayed by the nitrocellulose filter procedure. Analysis of the data revealed that each bound p12 molecule forms three ion pairs with the nucleic acid.

Animals↗
PubMed1979

Anti-inflammatory drugs in experimental atherosclerosis. Part 4. Inhibition of atherosclerosis in vivo and thromboxane synthesis and platelet aggregation in vitro.

Groups of New Zealand white male rabbits were fed atherogenic diets containing 1% cholesterol. The diets of experimental groups were supplemented additionally with either aspirin, phenylbutazone, mefenamic acid, flufenamic acid, oxyphenylbutazone or aminopyrine. Blood cholesterol and phospholipids were measured at 3--4 week intervals. After 12 weeks the animals were sacrificed and the severity of atherosclerosis in the thoracic aorta was measured. In separate experiments, rabbit platelets were incubated with each of the drugs individually and conversion of [14C]arachidonic acid to thromboxanes and related compounds was assayed. Inhibition of collagen and arachidonic acid-induced platelet aggregation by each drug was also measured. All drugs inhibited thromboxane synthesis and platelet aggregation in varying degrees with flufenamate and aspirin being most and aminopyrine least effective. The pattern of metabolite formation from [14C]arachidonate was consistent with a block in the cyclooxygenase reaction. Phenylbutazone, flufenamic acid and oxyphenylbutazone produced significant reductions in atherosclerotic plaque formation without major changes in blood cholesterol levels or blood cholesterol--phospholipid ratios. Aspirin and aminopyrine were ineffective. The results indicate that the effectiveness of anti-inflammatory drugs as inhibitors of thromboxane synthesis and platelet aggregation in vitro does not afford a sufficient predictive index of their anti-atherogenicity in vivo. The significance of these findings is discussed in terms of the possible involvement of cyclooxygenase derivatives in atherogenesis.

Aminopyrine↗
PubMed1979

Isolation of a new lipoxygenase metabolite of arachidonic acid, 8. 11, 12-trihydroxy-5,9,14-eicosatrienoic acid from human platelets.

Washed human platelets incubated with 1-14C-arachidonic acid (1mM) produced a new metabolite which migrated on thin layer chromatography close to thromboxane B2, but which was identified by mass spectrometry as a trihydroxy fatty acid. The mass spectrum was consistent with the assigned structure, 8,11,12-trihydroxy-5,9,14-eicosatrienoic acid (THETE). Platelet THETE synthesis from arachidonate was not inhibited by preincubation with asprin or indomethacin but was blocked by 5,8,11,14-eicosatetraynoic acid. Therefore, THETE appears to arise via the platelet lipoxygenase pathway rather than via the prostaglandin cyclooxygenase. Two proposed structures, including a novel dihydro-hydroxy-pyran cyclic intermediate, which could give rise to THETE are presented.

5,8,11,14-Eicosatetraynoic Acid↗
PubMed1979

Effects of onion (Allium cepa) extract on platelet aggregation and thromboxane synthesis.

Oral administration of onion and garlic reportedly decreases platelet aggregation in both human and animal subjects. An oily chloroform extract of onion (Allium Cepa) was prepared and separated by column chromatography on silicic acid into six fractions by elution with solvents of increasing polarity. The least polar fraction contained most of the inhibitory activity towards platelet aggregation induced by either ADP or arachidonic acid. Further purification was afforded by thin-layer chromatography. The specific activity of this major active fraction (I50 per ml of PRP) was approximately 7 units per milligram. Platelets incubated in the presence of onion inhibitor and (1-14C)-arachidonic acid showed striking changes in the pattern of arachidonic acid metabolites formed. Thromboxane B2 synthesis was almost completely suppressed without significant decreases in total hydroxy fatty acid formation. It was concluded that the observed antiplatelet activity of onion relates to the presence of a non-polar, heat stable inhibitor of thromboxane synthesis. This appears to be the first demonstration of this type of inhibitor present in significant quantities in a common foodstuff.

Adenosine Diphosphate↗
PubMed1979

Lipid metabolism in cultured cells. XVIII. Comparative uptake of low density and high density lipoproteins by normal, hypercholesterolemic and tumor virus-transformed human fibroblasts.

Serum lipoproteins control cell cholesterol content by regulating its uptake, biosynthesis, and excretion. Monolayers of cultured fibroblasts were used to study interactions with human high density (HDL) and low density (LDL) lipoproteins doubly labeled with [(3)H]cholesterol and (125)I in the apoprotein moiety. In the binding assay for LDL, the absence of specific LDL receptors in type II hypercholesterolemic fibroblasts was confirmed, whereas monolayers of virus-transformed human lung fibroblasts (VA-4) exhibited LDL binding characteristics essentially the same as normal lung fibroblasts. In the studies of HDL binding, specific HDL binding sites were demonstrated in normal and virus-transformed fibroblasts. In addition, type II hypercholesterolemic cells, despite the loss of LDL receptors, retained normal HDL binding sites. No significant competition was displayed between the two lipoprotein classes for their respective binding sites over a 5-fold concentration range. In VA-4 cells, the amount of lipoprotein required to saturate half the receptor sites was 3.5 micro g/ml (9 x 10(-9) M) for LDL and 9.1 micro g/ml (9 x 10(-8) M) for HDL. Pronase treatment reduced LDL binding by more than half but had no effect on HDL binding. Chloroquine, a lysomal enzyme inhibitor, stimulated net LDL uptake 3.5-fold by increasing internalized LDL but had essentially no effect on HDL uptake. Further experiments were conducted using doubly labeled lipoproteins to characterize the interaction of LDL and HDL with cells. While the cholesterol and protein moieties of LDL were incorporated into cells at similar rates, the uptake of the cholesterol moiety of HDL was 5 to 10 times more rapid than that of the protein component. Furthermore, the apoprotein component of LDL is extensively degraded following exposure, whereas the apoprotein moiety of HDL retains its macromolecular chromatographic characteristics. These results indicate that HDL and LDL bind to cultured cells at separate sites and that further processing of the two lipoprotein classes appears to take place by fundamentally different mechanisms.-Wu, J-D., J. Butler, and J. M. Bailey. Lipid metabolism in cultured cells XVIII. Comparative uptake of low density and high density lipoproteins by normal, hypercholesterolemic, and tumor virus-transformed human fibroblasts.

Animals↗
PubMed1977

Anti-inflammatory agents in experimental atherosclerosis. Part 2. Failure of antihypertensive drugs to exacerbate atherosclerotic plaque formation.

Hypertension is associated with an increased incidence of generalized vascular disease. Antihypertensive drug therapy, while decreasing overall mortality due to cerebral hemorrhage, myocardial hypertrophy or renal failure, paradoxically does not appear to reduce the incidence of coronary atherosclerosis. This study investigates whether the drugs, as a possible side effect, may have an adverse influence on the development of atherosclerotic plaques. Groups of rabbits were fed an atherogenic diet containing 1% cholesterol for 12 weeks. Two commonly used antihypertensive agents (methyldopa and chlorthalidone) were added to the diet of some groups at levels of 100 mg and 10 mg per day respectively. No significant increase in total atherosclerotic plaque area was produced by either of the drugs tested singly or in combination. Plasma renin levels were only mildly elevated and in this experimental system there was no correlation between renin activity and atherosclerotic plaque intensity. There is thus no evidence from this study that antihypertensive drugs have any adverse effects on atherosclerotic plaque formation. While the ineffectiveness of these drugs against coronary atherosclerosis may indicate that normalization of pressure cannot arrest changes already initiated, it also supports the possibility that association of atherosclerosis with hypertension may be symptomatic of a common underlying defect not correlated by normalizing blood pressure.

Animals↗
PubMed1977

Differential separation of thromboxanes from prostaglandins by one and two-dimensional thin layer chromatography.

[14C]-labelled thromboxane B2 and hydroxy fatty acids were isolated using thin layer and gas chromatographic procedures from human platelets incubated with [1-14C]-arachidonic acid. A number of TLC solvent systems were evaluated for differential separation of thromboxanes and hydroxy fatty acids from prostaglandins E2, A2, D2 and F2alpha. Chromatographic properities in nine different solvent systems are tabulated. Two dimensional TLC procedures suitable for complete resolution of mixtures of these compounds on a single plate were developed. The systems were used to demonstrate conversion of [1-14C]-arachidonic acid to thromboxane B2 and prostaglandin E2 by human lung fibroblasts in tissue culture.

Arachidonic Acids↗
PubMed1977

Lipid metabolism in cultured cells. XVI. Lipoprotein binding and HMG CoA reductase levels in normal and tumor virus-transformed human fibroblasts.

The loss in feedback control of cholesterol biosynthesis in tumor cells was examined in tissue culture. Human fibroblasts from normal subjects, SV40 tumor virus-transformed cell lines, and homozygous familial hypercholesterolemic cells as reference, were grown in tissue culture. Experiments were conducted to relate the regulatory enzyme for cholesterol biosynthesis, HMG CoA reductase, and the membrane-located binding receptors for low density lipoproteins (LDL) that mediate feedback control in normal cells. Monolayers of virus-transformed tumor cells exhibited specific (125)I-labeled LDL binding of 152 +/- 21 ng/mg cell protein, which was essentially the same as that of normal fibroblasts (135 +/- 20 ng/mg). Binding of LDL by familial hypercholesterolemic cells used as controls was only 8 +/- 3 ng/mg under the same test conditions. Basal levels of HMG CoA reductase in tumor cells of 45.2 +/- 6.5 units/mg cell protein were about twice those of normal cells. However, in contrast to the lack of feedback control of this enzyme observed with tumors in vivo, in both the normal and the transformed cells in vitro, activity of the enzyme decreased about fourfold when serum lipids were added. These findings demonstrate that tumor cells growing in vitro contain a normal complement of the membrane-located binding receptors for low density lipoproteins and, although the basal levels are higher than normal, an effective feedback regulation of the enzyme HMG CoA reductase is retained.

Alcohol Oxidoreductases↗
PubMed1976

RD-114, baboon, and woolly monkey viral RNA's compared in size and structure.

The molecular weights, subunit compositions, and secondary structure patterns of the RNAs from an endogenous baboon virus and from a woolly monkey sarcoma virus were examined and compared to the properties of the RNA of RD-114, an endogenous feline virus. The high molecular weight RNA extracted from each of these three viruses has a sedimentation coefficient of 52S, and a molecular length, measured by electron microscopy, of 16-20 kb (kb=kilobase, 1000 nucleotides). Each such RNA is a dimer, containing two monomer subunits of 8-10 kb in length (molecular weight 3 X 10(6) daltons). The two monomer subunits are joined at their non-poly(A) ends in a structure called the dimer linkage structure. The appearance of this structure is somewhat different for the different viruses. The dimer linkage dissociates at temperature estimated to be 87 degrees C in aqueous 0.1M Na+ for RD-114 and baboon viral RNAs, but at the lower temperature of 66 degrees C for woolly monkey RNA. All three viral RNAs have two large loops of similar size and position symmetrically placed on either side of the dimer linkage structure. Since the baboon virus is partially related to RD-114, and the woolly monkey virus is unrelated to either of the other two, the dimer linkage and symmetrical loops are surprisingly similar and may well be common features of type C virus RNAs.

Centrifugation, Density Gradient↗
PubMed1976

Plasma alkaline phosphatase in mice with experimentally-induced osteosarcomas.

No statistically significant difference in alkaline phosphatase levels was demonstrated in animals injected with the FBJ virus. However, there was a significant increase associated with the development of osteosarcomas in response to the iv injection of 1.0 uCi 90 Sr/g body weight into 11-18-mo-old Anl:CFl females. It was proposed that alkaline phosphatase determinations can be used as well as roentenographic analysis to detect 90Sr-induced tumors in mice.

Alkaline Phosphatase↗