A problem with a PCA pump handset.
Explore the source record for details and available documents.
Adolescent↗
Biomedical subjects
L Humble
Publications and source records attributed to L Humble.
Correlation between oxidation of low density lipoproteins and prostacyclin synthesis in cultured smooth muscle cells.
The effect of antioxidants on the oxidation of low density lipoproteins in relation to prostacyclin synthesis was investigated in the prescence of rabbit smooth muscle cells (SMC) and Fe-containing culture medium. The lipid peroxidation of low density lipoproteins (LDL) assayed as thiobarbituric acid reactive substances was increased from 0.5 to 1.4 nmol malondialdehyde/mL by the presence of smooth muscle cells. Two potent antioxidants, nordihydroguairetic acid (NDGA) and butylated hydroxytoluene (BHT), inhibited lipoprotein oxidation by IC50 values of 0.2 and 0.8 microM, respectively. Inhibition of lipoprotein oxidation was associated with an increased prostacyclin synthesis by the SMC, the effect being more pronounced with nordihydroguairetic acid than with butylated hydroxytoluene. The stable metabolite of the lipid hydroperoxide, 15-hydroxyeicosatetraenoic acid (15-HETE), formed in the 15-lipoxygenase pathway was measured following antioxidant treatment and found to be eliminated or greatly reduced by both antioxidants. The results presented show that lipid hydroperoxides, formed as a consequence of lipoprotein oxidation and promoted by the smooth muscle cells through a lipoxygenase reaction, may regulate prostacyclin synthase, a process which may be influenced by the addition of antioxidants.
Animals↗
Plasma very low density lipoproteins from male rats fed casein or soybean protein diets: a comparison of fatty acid composition and influence on prostanoid production.
In studies with male rats fed for 4 wk semipurified diets containing olive oil and casein or soybean protein, protein-dependent effects were observed in the fatty acid composition of the VLDL lipids, especially with regard to the pattern of polyunsaturated fatty acids. Compared with VLDL from rats fed soybean protein diet (S-VLDL), VLDL from casein-fed rats (C-VLDL) contained a greater level of oleic acid, and a reduced level of linoleic acid and arachidonic acid, in the phosphatidylcholine fraction. The proportion of 5,8,11-eicosatrienoic acid, 20:3 (n-9), varied among the different lipid classes. The highest concentration of this fatty acid (13% by weight of total fatty acids) was observed in the phosphatidylinositol fraction of C-VLDL. The level of linoleic acid was approximately halved in the triacylglycerol and cholesteryl ester fractions of C-VLDL compared with S-VLDL. When mouse peritoneal macrophages were incubated with different concentrations of S-VLDL, a saturable accumulation of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TXB2) was observed in the cell medium. In contrast, very low levels of 6-keto-PGF1 alpha and TXB2 were observed in the cell medium of macrophages incubated with C-VLDL at different lipoprotein concentrations, suggesting that the composition of VLDL may play an important role in relation to cellular prostanoid metabolism.
6-Ketoprostaglandin F1 alpha↗
The relationship between gastric acid secretion and gastric H+,K+-ATPase activity.
The H+,K+-ATPase has been postulated to be the enzyme responsible for H+ secretion by the parietal cell. Omeprazole has been shown to be an inhibitor of acid secretion in vivo, but also in in vitro test models for acid secretion, including partly purified H+,K+-ATPase, the inhibitory action of omeprazole has been demonstrated (Wallmark, B., Jaresten, B. M., Larsson, H., Ryberg, B., Brändström, A., and Fellenius, E. (1983) Am. J. Physiol. 245, G64-G71). It was thus possible to use this compound to demonstrate a correlation between H+,K+-ATPase activity in rat oxyntic mucosa and in vivo H+ secretion. Two results were found. (a) Increasing oral doses of omeprazole progressively inhibited acid secretion, H+,K+-ATPase activity, and phosphoenzyme formation of a microsomal fraction isolated from the inhibited rat mucosa. Furthermore, a Mg2+-stimulated ATPase activity, associated with the H+,K+-ATPase membrane fraction, was not affected by the omeprazole treatment. (b) Recovery of H+,K+-ATPase activity following complete omeprazole inhibition was correlated with the appearance of acid secretion. The results indicate a strict relationship between the activity of the gastric H+,K+-ATPase in the microsomal fraction and gastric acid secretion.
Adenosine Triphosphatases↗
Preparation of cells from pig gastric mucosa. Isolation of parietal cells by isopycnic centrifugation on linear density gradients of Percoll.
Cells were isolated from pig gastric mucosa by a combination of mechanical and enzymatic treatment. Isopycnic centrifugation on linear density gradients of Percoll provided a simple and rapid procedure for obtaining highly enriched parietal cells and chief cells. Their densities were 1.06 and 1.10 g/ml, respectively. Isolated mucosal cells attached to Petri dishes coated with fibronectin or collagen. Both parietal cells and chief cells adhered more readily to fibronectin than collagen. Mucosal cells and cells from the Percoll gradients were maintained for up to one week as primary cell cultures. The ability of free parietal cells to produce acid was tested by the 14C-aminopyrine accumulation technique. Maximal accumulation was 2.5 pmol aminopyrine per 10(4) parietal cells after incubation for 45 min at 10(-4) M histamine. The EC50 for histamine was 5 X 10(-6) M. The accumulation of aminopyrine at 10(-6) M carbachol and 10(-7) M pentagastrin were for both secretagogues about 0.9 pmol per 10(4) parietal cells.
Aminopyrine↗