Vitamin E levels in human atherosclerotic plaque: the influence of risk factors.

Recent studies suggest that vitamin E may be an important preventative factor in the development and progression of atherosclerosis. In order to more clearly define the role of vitamin E in atherosclerosis, we measured vitamin E, conjugated diens, and lipid flurochromes, as well as cholesterol, triglycerides and phospholipid in arterial and venous tissue of 83 patients. Serum cholesterol and triglyceride levels were significantly higher (P < 0.05) in patients with aortic occlusive (AIOD) and aneurysmal (AAA) disease than in control organ donors (OD). Tissue cholesterol concentrations were significantly elevated in AAA tissue when compared to OD and tissue from patients with peripheral occlusive disease (POD). Tissue from patients with AIOD contained greater concentrations of phospholipid (PL) than were measured in patients with POD and in OD. Vitamin E concentrations were highest in POD tissue and approximately 3.0, 2.0, and 1.6 fold greater than OD, AIOD and AAA tissue respectively. Diene conjugates and lipid flurochromes, measures of early and intermediate products of lipid peroxidation, were markedly elevated in all diseased arterial tissue compared to controls. There were no significant differences in tissue or serum lipid levels between saphenous vein (SVBG) and diseased vein grafts (DVG). However, conjugated diene concentrations were elevated in DVG compared to SVBG. Vitamin E levels were significantly elevated in diseased arterial and venous tissue (AIOD, AAA, POD, DVG) removed from patients with diabetes (P = 0.013) and hypertension (P = 0.049) compared to those without these risk factors. Diabetes was the only risk factor associated with significantly increased (P = 0.005) levels of vitamin E when only data from atherosclerotic arterial tissue (AAA, POD, AIOD) were analyzed. These preliminary data provide additional evidence of altered vitamin E metabolism and free radical processes in the tissues of patients with various manifestations of atherosclerosis.

Contrast-induced nephrotoxicity: the effects of vasodilator therapy.

The increasingly frequent use of contrast-enhanced imaging for diagnosis or intervention in patients with peripheral vascular disease has generated concern about the incidence and avoidance of contrast-induced nephrotoxicity (CIN). In this prospective study, we sought to identify those patients at greater risk of developing CIN and to evaluate the efficacy of vasodilator therapy with dopamine in limiting this complication. Baseline serum creatinine (Cr) concentrations were obtained on admission and daily for up to 72 hr after angiography in 222 patients undergoing 232 angiographic procedures. The preangiographic treatment was varied at 2-month intervals for 1 year. All patients received an intravenous infusion of 5% dextrose and 0.45% normal saline at a rate of 75 to 125 ml/hr. During the first interval patients received 12.5 g of 25% mannitol immediately prior to their contrast load, in addition to intravenous fluids. During the next 2-month period the patients were given renal dose dopamine intravenously (3 micrograms/kg/min) commencing the evening before angiography and continued to the next morning. During the latter half of the study the treatment regimens were modified so that the use of mannitol was restricted to patients with diabetes mellitus and dopamine to patients with serum creatinine concentrations of > or = 2 mg/dl. Postangiographic elevation in Cr occurred in 2, 10.4, and 62% of studies in patients with baseline creatinine levels of < or = 1.2 mg/dl, 1.3 to 1.9 mg/dl, and > or = 2.0 mg/dl, respectively. None of the patients receiving dopamine experienced an elevation in creatinine. There was no statistical correlation between age, diabetes, or medication with calcium channel blockers and CIN.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of epidermal growth factor on growth response, morphology, and invasive potential of human endometrial carcinoma cell line RL95-2.

Exposure of RL95-2 human endometrial adenosquamous carcinoma cells of early passage (less than 30 passages) and late passage (greater than 250 passages) to epidermal growth factor (EGF) resulted in density- and concentration-dependent effects. At low seeding density, EGF (20 nM) inhibited the growth of early passage cells, whereas at high seeding density, 4.98 nM and 20 nM concentrations of EGF stimulated their growth. Furthermore, the growth of late passage cells was stimulated by 0.0166 nM EGF and inhibited by 4.98 nM and 20 nM EGF at both seeding densities. EGF (20 nM) caused marked morphological changes of both passages at the low seeding density. Inhibition of invasion of both passages through Matrigel-coated filters was seen at low seeding density, while at the high seeding density, EGF enhanced invasiveness. At high seeding density, EGF stimulated an increase in urokinase type plasminogen activator activity, which may have augmented the ability of cells to degrade the extracellular matrix. In addition, the ability of high seeding density cells of both passages to adhere to matrigel after EGF treatment correlated with invasiveness.

Retinoic acid inhibition of human melanoma cell invasion through a reconstituted basement membrane and its relation to decreases in the expression of proteolytic enzymes and motility factor receptor.

Treatment of four A375 human melanoma sublines (A375, A375P, A375P-5, A375M), exhibiting distinct metastatic potentials in vivo, with beta-all-trans-retinoic acid in vitro caused a dose- and time-dependent inhibition of the ability of these cells to penetrate Matrigel-coated filters using a reconstituted basement membrane invasion assay. The possible mechanisms of action responsible for the antiinvasive effect were further investigated, and the data showed that compared with untreated cells the retinoic acid-treated cells: (a) secreted lower levels of collagenolytic enzymes, as demonstrated by a decreased ability of the cells to degrade [3H]proline-labeled type IV collagen substrate and by a reduction in the activity of a secreted Mr 64,000 collagenolytic enzyme detected in type IV collagen-containing polyacrylamide gels; (b) expressed lower levels of the human type IV collagenase mRNA (except in the A375P cells), as detected by Northern blot analysis; (c) exhibited decreased levels of tissue plasminogen activator activity, as demonstrated by a chromogenic assay; (d) were 10-40% less adhesive to a reconstituted basement membrane matrix, as determined by a 60-min Na2(51)CrO4-labeled cell attachment assay; (e) exhibited an increase in the high affinity metastasis-associated cell surface laminin receptor, as determined by flow cytometry after binding of fluorescently labeled laminin receptor antibody; and (f) expressed decreased amounts of gp78, a cell surface receptor for motility factor, demonstrated by immunoblotting and immunofluorescence. Collectively, these data suggest that retinoic acid inhibits tumor cell invasion through a basement membrane-like matrix by suppressing matrix degradation and by altering cell surface receptors.

Retinoic acid inhibits human melanoma tumor cell invasion.

The anticancer effects of retinoids have been recognized both in vivo and in vitro; however, little is known about their mechanism of action. Our study evaluated the effects of retinoic acid on the invasiveness of four human melanoma cell lines in vitro and showed a time-dependent inhibition of the ability of these cells to penetrate matrigel-coated filters. The possible mechanisms of action responsible for the anti-invasive effect were further investigated, and the data showed that retinoic acid-treated cells: (a) secreted lower levels of collagenolytic enzymes detected in type IV collagen-containing polyacrylamide gels compared with control cells, which was demonstrated by a decreased ability to degrade [3H]proline-labeled type IV collagen substrate; (b) showed a reduction in PA activity, primarily in the form of tPA, as demonstrated by chromogenic analysis; (c) showed a heterogeneous response with regard to c-myc, c-fos and c-jun mRNA expression, as determined by Northern blot analysis; and (d) demonstrated a decrease in B-actin levels and an increase in vimentin, as demonstrated by Northern blot analysis and SDS-PAGE transblot analysis. Collectively, these data suggest that RA causes an inhibitory effect on tumor cell invasion through a reconstituted basement basement membrane matrix by suppressing type IV collagenolytic activity and PA activity, which is probably triggered through a complex series of oncogene trans-acting factors, ultimately affecting cytoskeletal expression.

Comparison of tumor cell invasion assays: human amnion versus reconstituted basement membrane barriers.

This study compares two well-known tumor cell invasion assays: the human amnion model versus the reconstituted basement membrane (RBM) system in the membrane invasion culture system (MICS). Our purpose was to present the quantification of tumor cell invasion using visual counts and radioactivity assessment in a side-by-side comparison and then to determine reasons for discrepancies in data collection and reporting. Basically, the data showed that: (1) fewer tumor cells invade the amnion membrane compared with the RBM, and substantially more variability exists among the data generated from the amnion assay (probably due to differences in membrane thickness); and (2) the invasive ability of the tumor cells appears to be greater using the radiolabel technique in both the amnion and RBM assay, a portion of which appears to be artifactual. Using the RBM, it was possible to sequentially select several subpopulations of highly invasive tumor cells, which was not possible with the human amnion. The invasive and metastatic potentials of these subpopulations were compared with those of established cell lines (selected in vivo). When analyzed independently, a direct relationship was shown between an increase in invasive ability and an increase in metastatic potential for the sublines selected in vitro and the established lines. However, collectively, it is more difficult to correlate the invasive and metastatic profiles of the sublines versus the established lines, which can probably be attributed to selection factors present during the establishment of the individual cell populations.

In vitro quantification of melanoma tumor cell invasion.

In order to quantify the invasiveness of melanoma tumor cells in vitro, a modification of the amniotic basement membrane (BM) model, described by Liotta et al. (Cancer Letters, 11, 141, 1980), was used in combination with radiolabeled tumor cells. B16-F10 metastatic murine melanoma cells and a derived clone (B16-F10L) were prelabeled with 0.1 muCi/ml of [14C]thymidine for 20-24 h in serum-free medium at 37 degrees C. Following incubation, fetal bovine serum was added to a concentration of 5 per cent, and the cells were allowed to grow to confluency for the next 24-28 h. The labeled cells were seeded onto amniotic membranes situated in Membrane Invasion Culture System (MICS) chambers at a density of 2.5 X 10(4) per well. At various times points, radioactivity of tumor cells that completely traversed the membrane was determined using an under-the-membrane sampling method. The average percent invasion demonstrated by the B16-F10 line was 2.75 per cent, and 3.65 per cent exhibited by the B16-F10L cell line after 48-53 h in vitro. Since it was apparent that some variability in thickness existed among membrane samples, a morphological analysis was performed on five sectors of a three-inch-diameter sample from four different placentae. Differences and similarities in BM thickness within the same sector were noted by this technique and could possibly contribute to some variability observed in tumor cell invasion in this model. Another parameter examined was the proliferation of tumor cells in the upper and lower wells of the MICS chambers. By 48 h, approximately 32.1 per cent of the B16-F10 cell line as well as the clone had replicated in the upper wells associated with the BMs compared with a 32.9 per cent replication in the lower wells, which reaffirmed the viability of the tumor cells under experimental conditions and insured similarly replicating populations of cells. In order to quantify the invasiveness of radiolabeled tumor cells accurately through a biological membranous barrier, the proper concentration of cells must be used, tumor cell heterogeneity should be taken into consideration, the technique of sampling radiolabeled invasive cells should be critically analysed, and thickness of the membranous barrier should all be considered as possible important factors in the quantitative analyses.

Development of topical BAPN delivery system for acute spinal cord injury in dogs.

Topical sustained release of various medications by a subdurally implantable device at the site of spinal cord injury is considered advantageous in the treatment of early symptoms of tissue damage. A typical case is the interference with collagenous scar by beta-aminopropionitrile, inhibiting collagen polymerization. Four materials, silicone, polyethylene, polytetrafluoroethylene (PTFE), and polyacrylonitrile-based hydrogel were evaluated for biocompatibility in subcutaneous implantations. The hydrogel, the least reactive, was then compared with silicone sheets as subcural implants. The histology favored the hydrogel as the most inert material, which was then used for the construction of soft, pliable pouches, releasing the drug through the hydrated wall at a rate controlled by an osmotic pump.

Distribution of disulfiram in brain after carotid ligation in gerbils.

Aiming whether intraperitoneal administration of disulfiram (tetraethyl thiuram disulfide, DS) achieves potentially therapeutic drug concentrations in brain tissue, the behaviour of blood-brain barrier (BBB) to 14C-labelled DS in cerebral ischemia with and without simultaneous administration of dimethylsulfoxide (DMSO) was studied in Mongolian gerbils subjected to left common carotid artery (CCA) occlusion. The results indicated that: (a) the permeability of DS through the BBB was significantly enhanced in the ischemic brain during the initial 30 min duration after DS administration; (b) administration of DMSO increased the entry of DS into the ischemic brain five-fold during the first 30 min and it was significantly higher even at the 60 min sampling period; (3) in general, the content of DS in the brain was quickly reduced with time.

Inhibition of lipid peroxidation in spinal cord homogenates by various drugs.

The extent and kinetic profiles of lipid peroxidation induced with Fe2+-ascorbic acid in a homogenate of spinal cord from greyhound dogs were ascertained by measurement of the formation of malondialdehyde (MDA) and chemiluminescence in the presence of four drugs. Changes in MDA and chemiluminescence were correlated as a function of the activator or inhibitors. The kinetic profiles of chemiluminescence which were observed for 25 min after addition of the activator and individual inhibitors were similar regardless of the type of inhibitor studied. The most effective inhibition was by disulfiram which was approximately 11 and 33 times more effective than two other inhibitors, propyl gallate and promethazine, respectively, and 11,000 times more effective than D-alpha-tocopherol.

Vascular manifestations in patients with Ehlers-Danlos syndrome.

Ehlers-Danlos syndrome (EDS) is clinically and genetically a heterogenous disorder of connective tissue synthesis. Seven clinical types of this disease have been identified and the underlying biochemical defects defined in types IV through VII. Unfortunately, most patients with major vascular complications of EDS have few, if any of the commonly recognized musculoskeletal and cutaneous abnormalities. Recognition of the correct diagnosis and the application of accepted vascular surgical techniques may improve the morbidity and mortality for these patients.

Interaction of zinc ions with electron carrying coenzymes NADPH and NADH.

Evidence is presented that the substrate for the drug oxidizing system, NADPH, binds to zinc ions. Zinc ions bind selectively to NADPH but not to NADH. By using equilibrium gel filtration and acid titrations of Zn2+ and NADPH, the molar ratio of metal to nucleotide was determined at 2 : 1, as well as the formation constant of 10(6.75). Results from 31P-nuclear magnetic resonance (NMR), ultraviolet and fluorescence spectra of the complex indicated the possible binding sites of zinc to NADPH. In previous studies we have shown that zinc ions inhibit the metabolism of drugs by mixed function oxidases in liver microsomes. The formation of the Zn2+-NADPH complex suggests the mechanism by which zinc ions may inhibit the drug oxidizing system.