Effect of inorganic lead on some functions of the cerebral microvessel endothelium.

The effect of inorganic lead on two functions of cerebral microvessel endothelium, cell division and glucose analog uptake, was investigated. Lead concentrations considered to be toxic in humans inhibited both functions in cultured endothelial cells. Both effects were dependent on the length of lead exposure and dose over the range of 10(-4) to 10(-6) M lead acetate.

Monocyte chemotactic factor produced by large vessel endothelial cells in vitro.

Cultured rabbit aortic and human carotid artery endothelial cells produced a factor that was chemotactic for monocytes but not for neutrophils. Checkerboard analysis showed that the activity was due to chemotaxis and not to chemokinesis. The factor was produced in both serum-containing and serumless media.

Insulin stimulates DNA synthesis in cerebral microvessel endothelium and smooth muscle.

Experiments were performed to test the hypothesis that insulin stimulates DNA synthesis in cerebral microvessel endothelium and smooth muscle. Cultured endothelium and smooth muscle derived from isolated mouse cerebral microvessels were exposed to insulin in serum-free medium, and [3H]-thymidine incorporation in the cells was measured. Up to 40-fold stimulation of DNA synthesis in endothelium and fourfold stimulation in smooth muscle were observed.

Uptake of glucose analogues into cultured cerebral microvessel endothelium.

Tritiated glucose analogues 3-O-methylglucose (3-OMG) and 2-deoxyglucose (2-DG) were used to study glucose uptake properties in established lines of cultured mouse cerebral microvessel endothelium. Uptake of both analogues was similar in terms of rate and absolute amount for the first two minutes. Thereafter, intracellular accumulation of 2-DG continued at a more rapid rate because of intracellular phosphorylation of this substrate.

Dissociation of thrombin generation and platelet secretion in diabetes mellitus.

To determine the relationship between thrombin generation and platelet secretion in vivo in diabetes mellitus, we measured simultaneous plasma beta-thromboglobulin (BTG) and fibrinopeptide A (FPA) in 40 insulin-dependent patients without renal disease, and 20 control subjects of similar age. Log mean plasma BTG and FPA were higher in diabetic patients (32.1 vs 23.

Magnetic resonance imaging of biological specimens by electron paramagnetic resonance of nitroxide spin labels.

Electron paramagnetic resonance imaging was demonstrated on two plant species, Apium graveolens and Coleus blumei. This was accomplished by soaking stems of these plants in the paramagnetic nitroxide imaging agent 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl. The experiments were accomplished at L-band frequency (1.

Plasma beta-thromboglobulin is correlated with platelet adhesiveness to bovine endothelium in patients with diabetes mellitus.

We measured simultaneous plasma beta-thromboglobulin (BTG) and adhesion of 51Cr-labelled, washed platelets to confluent, bovine aortic endothelial monolayers in 50 insulin-dependent diabetic patients and 30 normal subjects (respective mean ages (+/- SD) = 45.1 +/- 16.4 and 45.

Effect of monocyte migration on low density lipoprotein transport across aortic endothelial cell monolayers.

Endothelial cell monolayers on polycarbonate filters present a barrier to low density lipoprotein (LDL) and albumin transport. These cells form a relatively tight monolayer as shown by measurements of electrical resistance across the monolayer (15 omega-cm2). Monocytes are able to migrate freely across the monolayers in response to chemotactic stimuli.

Lipoprotein-induced insulin resistance in aortic endothelium.

An in vitro model system employing cultured, adult, bovine aortic endothelial cells was used to study the mechanism of insulin stimulation of aminoisobutyric acid (AIB) uptake and the effects of low-density lipoprotein (LDL), malondialdehyde-altered LDL (MDA-LDL), and B-migrating very-low-density lipoprotein (B-VLDL) on this process. The insulin response was maximal after treatment with insulin for 2 h (at a concentration of 5 X 10(-8) M). Insulin increased the Vmax but not the KM of the uptake response.

Intensity perception. XIII. Perceptual anchor model of context-coding.

In our preliminary theory of intensity resolution [e.g., see N.

LDL, scavenger, and beta-VLDL receptors on aortic endothelial cells.

Primary and first passage aortic endothelial cells were shown to possess a high affinity receptor for beta-migrating very low density lipoproteins (beta-VLDL) distinct from the low density lipoprotein (LDL) receptor and scavenger receptor on these cells. In bovine aortic endothelial cells, 125I-rabbit beta-VLDL was taken up and degraded by a high affinity process that was competed for by unlabeled rabbit beta-VLDL and unlabeled postprandial VLDL from a fat-fed normal subject. However, unlabeled human or rabbit LDL, human LDL modified by malondialdehyde (MDA-LDL), or VLDL from a fasted normal human or a rabbit were not effective competitors for the degradation of 125I-rabbit beta-VLDL.

Lymphokines secreted by an established lymphocyte line modulate receptor-mediated endocytosis in macrophages derived from human monocytes.

As little as 1 microliter of serum-free supernatant from Mo(t), an established lymphocyte line, when added to a 500-microliters incubation of macrophages derived from human monocytes, significantly decreased the receptor-mediated uptake and degradation of three cholesterol-rich molecules: low density lipoprotein (LDL); LDL complexed to dextran sulfate; and LDL modified by malondialdehyde (MDA-LDL). In contrast, the receptor-mediated uptake and degradation of mannosyl bovine serum albumin was increased three-fold. The Mo(t) supernatant did not contain competitive inhibitors of the cholesterol-rich ligands, and it did not alter macrophage receptor-independent endocytosis, protein synthesis, or phagocytosis of heat-killed yeast.

Characterization of NADPH-cytochrome P-450 reductase in a mouse hepatoma cell line.

NADPH-cytochrome c reductase in Hepa-1 cells was induced 2-fold by phenobarbital, but was not induced by benz[a]anthracene or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The apparent Km of the enzyme for NADPH was 0.57 microM; the activity was inhibitable by NADP; and segregated primarily to the microsomal fraction.

Electron microscopic examination of lead treated L6 skeletal muscle line cells in culture.

A study has been made of the effects of lead on developing muscle using a cell culture system. When the L6 clonal cell line was treated with lead acetate in culture during the first or second day after plating (but not at later times) fusion of cells to form skeletal muscle straps was inhibited. This inhibition was not due to a general toxic effect of lead on the cells since cell division continued at a normal rate during the first 10 days of culture after lead addition.

An in vitro study of the effects of lead on an epithelioid cell line.

The effects of a growth-inhibiting dose of lead on the cell surface, mitochondria, and vacuoles of RLC-GAI cells, an epithelioid cell line, were examined. The cells were found to begin to retract from the culture dish, becoming rounded in shape as early as 6 hours after lead addition. The rounded cells were found to be more susceptible to osmotic shock than normal cells.

Intensity perception. IX. Effect of a fixed standard on resolution in identification.

This note reports some measurements of the changes in identification performance that result form presenting a fixed standard before each trial. These measurements indicate that the presence of the standard improves performance for test stimuli in the vicinity of the standard, except when the standard is near the extremes of the stimulus range.

Effect of hydrocortisone on cell morphology in C6 cells.

Hydrocortisone has been found to induce cell spreading in rat glial C6 cells by 24 hours after its addition. This spreading phenomenon is correlated with an increase in the fraction of the peripheral cytoplasm occupied by microfilaments. Cytochalasin B causes disorganization of microfilaments in the peripheral cytoplasm of the cells.

Hormonal regulation of cultured rabbit endometrial cells.

A technique for culturing primary explants of rabbit endometrial cells in chemically defined medium has been developed. Diethylstilbestrol and natural estrogens were found to increase the rate of DNA initiation while progesterone had the opposite effect. Ultrastructural studies revealed that with estrogens, the cultures had the appearance of rapidly dividing cells having large euchromatic nuclei and prominent nucleoli, with aboundant free ribosomes in the cytoplasm.