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PubMed2004

Quantitative trait loci associated with drought tolerance at reproductive stage in rice.

Drought is a major constraint to rice (Oryza sativa) yield and its stability in rainfed and poorly irrigated environments. Identifying genomic regions influencing the response of yield and its components to water deficits will aid in our understanding of the genetics of drought tolerance and development of more drought tolerant cultivars. Quantitative trait loci (QTL) for grain yield and its components and other agronomic traits were identified using a subset of 154 doubled haploid lines derived from a cross between two rice cultivars, CT9993-510 to 1-M and IR62266-42 to 6-2. Drought stress treatments were managed by use of a line source sprinkler irrigation system, which provided a linearly decreasing level of irrigation coinciding with the sensitive reproductive growth stages. The research was conducted at the Ubon Rice Research Center, Ubon, Thailand. A total of 77 QTL were identified for grain yield and its components under varying levels of water stress. Out of the total of 77 QTL, the number of QTL per trait were: 7-grain yield (GY); 8-biological yield (BY); 6-harvest index (HI); 5-d to flowering after initiation of irrigation gradient (DFAIG); 10-total spikelet number (TSN); 7-percent spikelet sterility (PSS); 23-panicle number (PN); and 11-plant height (PH). The phenotypic variation explained by individual QTL ranged from 7.5% to 55.7%. Under well-watered conditions, we observed a high genetic association for BY, HI, DFAIG, PSS, TSN, PH, and GY. However, only BY and HI were found to be significantly associated with GY under drought treatments. QTL flanked by markers RG104 to RM231, EMP2_2 to RM127, and G2132 to RZ598 on chromosomes 3, 4, and 8 were associated with GY, HI, DFAIG, BY, PSS, and PN under drought treatments. The aggregate effects of these QTL on chromosomes 3, 4, and 8 resulted in higher grain yield. These QTL will be useful for rainfed rice improvement, and will also contribute to our understanding of the genetic control of GY under drought conditions at the sensitive reproductive stage. Close linkage or pleiotropy may be responsible for the coincidence of QTL detected in this experiment. Digenic interactions between QTL main effects for GY, BY, HI, and PSS were observed under irrigation treatments. Most (but not all) DH lines have the same response in measure of productivity when the intensity of water deficit was increased, but no QTL by irrigation treatment interaction was detected. The identification of genomic regions associated with GY and its components under drought stress will be useful for marker-based approaches to improve GY and its stability for farmers in drought-prone rice environments.

Adaptation, Physiological↗
PubMed2001

Induction of desiccation tolerance in plant somatic embryos: how exclusive is the protective role of sugars?

Plant somatic embryos usually lack desiccation tolerance. They may acquire such a tolerance upon preculture in the presence of abscisic acid (ABA), followed by slow drying, but not fast drying. ABA causes torpedo-shaped somatic embryos to lose their chlorophyll, suspend growth, exhibit low rates of respiration, and maintain elevated sucrose contents. The subsequent slow drying leads to a partial conversion of sucrose into oligosaccharides and the expression of dehydrin transcripts. Slow-dried, desiccation-tolerant somatic embryos have stable membranes, retain their native protein secondary structure, and have a densely packed cytoplasmic glassy matrix. Fast-dried, desiccation-sensitive somatic embryos experience some loss of phospholipids and an increase in free fatty acids. Their proteins show signs of denaturation and aggregation, and the glassy matrix has reduced hydrogen bonding. The reduced conversion of sucrose into oligosaccharides appears not to underlie dehydration injury. Proteins in slow-dried somatic embryos, not pretreated with ABA, also show signs of denaturation, which might be attributed to low sugar contents. We conclude that by reducing cellular metabolism, ABA maintains high sugar contents. These sugars contribute to the stability of membranes, proteins, and the cytoplasmic glassy matrix, whereas slow drying permits a further fine tuning of this stability. Partitioning of endogenous amphiphiles from the cytoplasm into membranes during drying may cause membrane perturbance, although it might confer protection to membranes in the case of amphiphilic antioxidants. The perturbance appears to be effectively controlled in desiccation-tolerant systems but not in sensitive systems, for which we suggest dehydrins are responsible. In this context, the low desiccation tolerance in the presence of ample sugars is discussed.

Abscisic Acid↗
PubMed2005

Discovery, structural determination, and putative processing of the precursor protein that produces the cyclic trypsin inhibitor sunflower trypsin inhibitor 1.

Backbone-cyclized proteins are becoming increasingly well known, although the mechanism by which they are processed from linear precursors is poorly understood. In this report the sequence and structure of the linear precursor of a cyclic trypsin inhibitor, sunflower trypsin inhibitor 1 (SFTI-1) from sunflower seeds, is described. The structure indicates that the major elements of the reactive site loop of SFTI-1 are present before processing. This may have importance for a protease-mediated cyclizing reaction as the rigidity of SFTI-1 may drive the equilibrium of the reaction catalyzed by proteolytic enzymes toward the formation of a peptide bond rather than the normal cleavage reaction. The occurrence of residues in the SFTI-1 precursor susceptible to cleavage by asparaginyl proteases strengthens theories that involve this enzyme in the processing of SFTI-1 and further implicates it in the processing of another family of plant cyclic proteins, the cyclotides. The precursor reported here also indicates that despite strong active site sequence homology, SFTI-1 has no other similarities with the Bowman-Birk trypsin inhibitors, presenting interesting evolutionary questions.

Amino Acid Sequence↗
PubMed1987

Neointimal hyperplasia occurring after carotid endarterectomy in a canine model: effect of endothelial cell seeding vs. perioperative aspirin.

Neointimal hyperplasia of the arterial wall may occur after carotid endarterectomy. This proliferative lesion is a pathologic response of the injured arterial wall and may lead to progressive stenosis. We investigated the effect of endothelial cell seeding (ECS) or antiplatelet therapy with aspirin (ASA) on inhibition of this lesion in a canine model. Endarterectomies were performed in 160 carotid arteries; 46 endarterectomies were treated perioperatively with aspirin (325 mg per day), 34 were seeded with a high density (3 X 10(6)) of autogenous endothelial cells, and 80 were untreated control arteries. At selected time intervals, the patent arteries were perfusion-fixed and the cross-sectional area (measured in square millimeters) of neointimal hyperplasia was measured by means of digital planimetry. At 6 weeks, patency of the endarterectomized carotid artery was 88% in the ASA and ECS groups, in contrast to 35% in the control group (p less than 0.01). The cross-sectional area of neointimal hyperplasia was not significantly different in the ASA and the control groups at 6 weeks. However, the ECS group showed a marked reduction in neointimal hyperplasia at 6 weeks (p less than 0.01). This inhibition of neointimal hyperplasia after carotid endarterectomy by ECS may reflect accelerated luminal healing or a direct inhibition of smooth muscle cell proliferation in the injured arterial wall.

Animals↗
PubMed2004

Surface physicochemical properties of globulin-P amaranth protein.

Globulin-P, the polymerized 11S amaranth globulin, is composed of 280 kDa unitary molecules (UM, 23%) and aggregates larger than 500 kDa (A, 70%). Antibodies against these proteins were prepared to study their surface characteristics and to assess their homology with other storage proteins. Results showed that globulin-P unitary molecules and aggregates had similar reactive surfaces. A polypeptide of 56 kDa was found to be the most reactive to the antibodies assayed, followed by the acidic polypeptides. Such results support previous information, according to which these polypeptides appeared to be the most exposed on the molecule surface. Globulin-P fraction presented cross-reactivity with the remaining amaranth protein fractions: 11S-globulin, glutelins, and albumins. Globulin-P and 11S-globulin showed similar reactive surfaces whereas glutelin and albumins presented a lower cross-reactivity. The reactivity of the glutelin fraction depended on its sequence. Globulin-P fraction presented cross-reactivity with quinoa globulins, and to a lesser extent with globulins of sunflower and rice. Moreover, the anti-Gp serum was unable to detect either conformational or sequence epitopes in globulins of soybean, wheat, buckwheat, rice, and rye.

Amaranthus↗
PubMed2001

The effects of sustained delivery of growth promoting hormones on the proliferation of MG63 cells in culture.

Bone matrix proteins are being identified in mineralized foci in several different pathological states. Irrespective of how these proteins become localized it is of great interest to further define what endocrine factors are necessary for triggering the release of bone matrix proteins. MG63 cells (Osteosarcoma cell line) were seeded at a density of 1 x 10(5) cells/ml onto two 24 well tissue culture plates. The wells were divided into 8 groups of 6 wells/group. Cells in group 1 were provided with media alone and served as a control. Cells in group II, IV, and VI were supplemented with Insulin Like Growth factor-1 (IGF-1), Testosterone (T), or Growth Hormone (GH), respectively. Cells in groups III, V and VII were supplemented with TCPL capsules containing IGF-1, Test or GH, respectively. Cells in group VIII were incubated with sham TCPL and served as vehicle control. Cells were incubated in the presence or absence of hormones for 24, 48 and 72 hours. At the end of each phase, cell damage, cell morphology, cell number and cellular protein concentrations were determined. The results showed a significant increase in MDA initially in all groups, followed by a drop in MDA levels by the 48-hour phase, and thereafter remaining lower than the control. Results also demonstrated a decrease in total cellular protein following administration of hormones by conventional means. Sustained delivery of the hormones by TCPL resulted in only a slight increase in protein levels. Cell count data showed an initial decrease in all groups, followed by a significant increase in cell number at the end of 48 hours and, finally, reaching control levels at the 72 hour period. Morphological evaluation revealed major structural changes associated with sustained delivery as compared to conventional delivery of hormones. For example, sustained delivery of IGF-1 and T resulted in an increase in mitotic figures, swelling, and aggregate formation. Cluster cellular formation were observed on cells exposed to IGF-1 and T by conventional routes.

Calcium Phosphates↗
PubMed2003

Conformational polymorphism of the amyloidogenic peptide homologous to residues 113-127 of the prion protein.

Conformational transitions are thought to be the prime mechanism of amyloid formation in prion diseases. The prion proteins are known to exhibit polymorphic behavior that explains their ability of "conformation switching" facilitated by structured "seeds" consisting of transformed proteins. Oligopeptides containing prion sequences showing the polymorphism are not known even though amyloid formation is observed in these fragments. In this work, we have observed polymorphism in a 15-residue peptide PrP (113-127) that is known to form amyloid fibrils on aging. To see the polymorphic behavior of this peptide in different solvent environments, circular dichroism (CD) spectroscopic studies on an aqueous solution of PrP (113-127) in different trifluoroethanol (TFE) concentrations were carried out. The results show that PrP (113-127) have sheet preference in lower TFE concentration whereas it has more helical conformation in higher TFE content (>40%). The structural transitions involved in TFE solvent were studied using interval-scan CD and FT-IR studies. It is interesting to note that the alpha-helical structure persists throughout the structural transition process involved in amyloid fibril formation implicating the involvement of both N- and C-terminal sequences. To unravel the role of the N-terminal region in the polymorphism of the PrP (113-127), CD studies on another synthetic peptide, PrP (113-120) were carried out. PrP(113-120) exhibits random coil conformation in 100% water and helical conformation in 100% TFE, indicating the importance of full-length sequence for beta-sheet formation. Besides, the influence of different chemico-physical conditions such as concentration, pH, ionic strength, and membrane like environment on the secondary structure of the peptide PrP (113-127) has been investigated. At higher concentration, PrP (113-127) shows features of sheet conformation even in 100% TFE suggesting aggregation. In the presence of 5% solution of sodium dodecyl sulfate, PrP (113-127) takes high alpha-helical propensity. The environment-dependent conformational polymorphism of PrP (113-127) and its marked tendency to form stable beta-sheet structure at acidic pH could account for its conformation switching behavior from alpha-helix to beta-sheet. This work emphasizes the coordinative involvement of N-terminal and C-terminal sequences in the self-assembly of PrP (113-127).

Amyloid beta-Peptides↗
PubMed2001

Near-field amplification of antithrombotic effects of dipyridamole through vessel wall cells.

Many studies have demonstrated that dipyridamole is not purely an antiplatelet agent but also exerts its antithrombotic properties through the vessel wall. Using a laboratory model in which bovine endothelial cells are seeded to form a subendothelial matrix (SEM), investigators have shown that dipyridamole enhances the antithrombotic action of the endothelium, probably by increasing intracellular levels of cAMP and cGMP through phosphodiesterase inhibition. If so, the antithrombotic action of dipyridamole should also be observable away from the endothelium itself, i.e., a near-field effect. To test this hypothesis, we reseeded the SEM with a monolayer of human umbilical vein endothelial cells (hUVECs), occluding a portion of the SEM with teflon stops. We then treated the SEM with and without hUVECs with various doses of dipyridamole and exposed them to whole blood under flow conditions. Human endothelial cells cultured on the SEM increased its ability to reduce thrombus formation in the adjacent SEM. Dipyridamole enhanced this antithrombotic effect of hUVECs in a dose-dependent manner. No increment in antithrombotic effect was seen in dipyridamole-treated SEM without hUVECs. We therefore conclude that endothelial cells have near-field antithrombotic properties that are enhanced by dipyridamole. Possible explanations for the near-field enhancement effect of dipyridamole are discussed in light of the published literature.

Cells, Cultured↗
PubMed2002

Maize HSP101 plays important roles in both induced and basal thermotolerance and primary root growth.

HSP101 belongs to the ClpB protein subfamily whose members promote the renaturation of protein aggregates and are essential for the induction of thermotolerance. We found that maize HSP101 accumulated in mature kernels in the absence of heat stress. At optimal temperatures, HSP101 disappeared within the first 3 days after imbibition, although its levels increased in response to heat shock. In embryonic cells, HSP101 concentrated in the nucleus and in some nucleoli. Hsp101 maps near the umc132 and npi280 markers on chromosome 6. Five maize hsp101-m-::Mu1 alleles were isolated. Mutants were null for HSP101 and defective in both induced and basal thermotolerance. Moreover, during the first 3 days after imbibition, primary roots grew faster in the mutants at optimal temperature. Thus, HSP101 is a nucleus-localized protein that, in addition to its role in thermotolerance, negatively influences the growth rate of the primary root. HSP101 is dispensable for proper embryo and whole plant development in the absence of heat stress.

Acclimatization↗
PubMed1997

Aluminum-induced structural alterations of the precursor of the non-A beta component of Alzheimer's disease amyloid.

The precursor of the non-A beta component of Alzheimer's disease amyloid (NACP) is a presynaptic protein whose function has been suspected to be tightly involved in neuronal biogenesis including synaptic regulations. NACP was suggested to seed the neuritic plaque formation in the presence of A beta during the development of Alzheimer's disease (AD). Recombinant NACP purified through heat treatment, DEAE-Sephacel anion-exchange, Sephacryl S-200 size-exclusion, and S-Sepharose cation-exchange chromatography steps appeared as a single band on SDS-PAGE with Mr of 19 kDa. Its N-terminal amino acid sequence clearly confirmed that the protein was NACP. Interestingly, however, the protein was split into a doublet on a nondenaturing (ND)-PAGE with equal intensities. The doublet was located slightly above a 45-kDa marker protein on a 12.5% ND-PAGE. In addition, the size of NACP was more carefully estimated as 53 kDa with high-performance gel-permeation chromatography using a TSK G3000sw size-exclusion column. Recently, Lansbury and his colleagues (Biochemistry 35, 13709-13715) have reported that NACP exists as an elongated "natively unfolded" structure which would make the protein more actively involved in protein-protein interactions and Kim (Mol. Cells 7, 78-83) has also shown that the natively unfolded protein is extremely sensitive to proteases. Here, we report that the structure of NACP could be altered by certain environmental factors. Aluminum, a suspected risk factor for AD, converged the doublet of NACP into a singlet with slightly lower mobility on ND-PAGE. Spectroscopic analysis employing uv absorption, intrinsic fluorescence, and circular dichroism indicated that NACP experienced the structural alterations in the presence of aluminum such as the secondary structure transition to generate about 33% alpha-helix. This altered structure of NACP became resistant to proteases such as trypsin, alpha-chymotrypsin, and calpain. Therefore, it is suggested that aluminum, which influences two pathologically critical processes in AD such as the protein turnover and the protein aggregation via the structural modifications, could participate in the disease.

Aluminum↗
PubMedDate not supplied

Epidermal growth factor stimulates colony formation and non-neuronal marker protein expression by human neuroblastoma in methylcellulose culture.

Growth of the human neuroblastoma IMR-32 in methylcellulose culture was studied. The number of colonies was proportional to the number of seeded cells in all conditions tested: control cultures (CT) and test cultures with epidermal growth factor (EGF), hydrocortisone (HC), combined EGF/HC, fibroblast growth factor (FGF) or nerve growth factor (NGF). A portion of IMR-32 cells formed colonies and all factors were without effect when tested individually. In contrast, the combination of EGF/HC at low cell densities enhanced the number of colonies two-fold as compared to controls. Differentiation in IMR-32 colonies was examined by immunocytochemical detection of cell specific marker proteins. As determined by staining with different markers, at least two cells subpopulations could be established within the same colony. One of them expressed NSE (neuron specific enolase) and was designated as neuronal. The other subpopulation was called non-neuronal since it consisted of vimentin and S-100 protein positive cells which were considerably enhanced in the presence of EGF or EGF/HC. In vitro, the IMR-32 neuroblastoma cell line contains pluripotent stem cells from which are derived distinct phenotypes sensitive to different extrinsic factors. Increasing time in culture enhanced neuronal differentiation. EGF, on the other hand, targeted preferentially the non-neuronal phenotype, and stimulated colony formation and its differentiation.

Antigens, Neoplasm↗
PubMed2004

Free exchange across cells, and echistatin-sensitive membrane target for the metastasis inhibitor NAMI-A (imidazolium trans-imidazole dimethyl sulfoxide tetrachlororuthenate) on KB tumor cells.

The duration of cell proadhesive effects induced by imidazolium trans-imidazole dimethyl sulfoxide tetrachlororuthenate (NAMI-A), a compound endowed with in vivo antimetastatic properties, was tested in vitro on the human epithelial tumor cell line KB. The intensity of proadhesive effects continues to increase up to 48 to 72 h after NAMI-A withdrawal and declines only after 96 h. The proadhesive effect on cells seeded on fibronectin is greater than on plastic, since it already reaches its maximum after 24 h. This effect suggests a role for integrin activation, which is further stressed by the inhibitory activity of the disintegrin molecule echistatin. The intensity and duration of NAMI-A's proadhesive effects are correlated to cell exposure time and to the rapid release of NAMI-A metabolites in the culture medium in the first 5 min after drug withdrawal. These metabolites are probably neutral species with ruthenium-bound bioligands to allow for the rapid exchange between cells and extracellular medium. These data suggest a long-lasting effect of NAMI-A in biological systems, even at very low concentrations, and stress the low and reversible effects on kidney, where it naturally concentrates. These data on proadhesive effects are, further, relevant for in vivo antimetastatic effects, as this adhesion is associated to cell motility and invasion, which in turn are related to tumor malignancy and metastasis.

Antineoplastic Agents↗
PubMed1983

Flow cytometric studies of oxidative product formation by neutrophils: a graded response to membrane stimulation.

We have developed a quantitative assay to monitor the oxidative burst (H2O2 production) of polymorphonuclear leukocytes (PMNL) using single cell analysis by flow cytometry, and have examined whether PMNL respond to membrane stimulation with an all-or-none oxidative burst. During incubation with normal neutrophils, dichlorofluorescin diacetate diffused into the cells, was hydrolyzed to 2',7'-dichlorofluorescin (DCFH) and was thereby trapped within the cells. The intracellular DCFH, a nonfluorescent fluorescein analogue, was oxidized to highly fluorescent 2',7'-dichlorofluorescein (DCF) by PMNL stimulated by phorbol myristate acetate (PMA). That the oxidative product was DCF was shown by excitation/emission spectra and by mass spectrometry of the product from PMA-stimulated PMNL. Normal resting and PMA-stimulated PMNL oxidized 6.9 +/- 0.7 and 160 +/- 13 attomoles DCF per cell, respectively, in 15 min. Absence of calcium and magnesium ions and/or addition of 2 mM EDTA did not inhibit DCF formation by PMNL stimulated by 100 ng/ml PMA. Since EDTA prevented aggregation of PMNL (even when stimulated by 100 ng/ml PMA), which would prevent accurate flow cytometric analysis, further experiments were performed with EDTA in the medium. A close correlation between average DCFH oxidation and hexose monophosphate shunt stimulation was demonstrated using cells from patients whose PMNL had oxidative metabolic defects of varying severity. Intracellular DCFH was also oxidized by reagent H2O2 or oxygen derivatives generated by glucose oxidase + glucose or by xanthine oxidase + acetaldehyde; DCFH oxidation by these systems was inhibited by catalase but unchanged by superoxide dismutase. The data indicate that the DCFH oxidation assay is quantitatively related to the oxidative metabolic burst of PMNL, and they strongly suggest that the reaction is mediated by H2O2 generated by the PMNL. Incubation of PMNL with varying concentrations of PMA caused graded responses by all PMNL present; i.e., 1 ng/ml PMA caused a mean response of 34% maximal with a single population of responding PMNL (rather than 66% resting and 34% fully stimulated as predicted by the all-or-none hypothesis). Thus, with these assay conditions, oxidative product formation by PMNL occurs as a graded response to membrane stimulation by PMA.

Flow Cytometry↗
PubMed2006

Oryctes monoceros trapping with synthetic pheromone and palm material in Ivory Coast.

Oryctes monoceros is the most serious pest in coconut plantations, causing up to 40% damage in tropical Africa, especially in Ivory Coast. With a view to reducing pest populations by olfactory trapping, field trials were carried out to assess the efficiency of a synthetic aggregation pheromone: ethyl 4-methyloctanoate (1), 4-methyloctanoic acid (2), a related volatile produced by males, and decaying palm material, either oil palm empty fruit bunches (EFB) or pieces of coconut wood (CW) of various ages. Vertical polyvinyl chloride tube traps (2 x 0.16 m with two openings in the upper half), embedded in the soil, were more efficient than 30-L pail traps 1.5 m above ground. EFB, which were inactive alone, synergized captures with synthetic pheromone. CW was more effective than EFB in comparative trials. Compound 2 did not catch any beetles when assessed with EFB, and reduced catches by 1 + EFB when tested at >10% with the pheromone. Trapping over 6 mo in 2002 and 2003 in a 19-ha coconut plot inside a 4,000-ha oil palm estate reduced damage from 3.8% in 2001 to 0.5% in 2002, then to 0.2% in 2003. Damage was 0.0% in 2004 with routine trapping using 32 traps, which caught 3369 beetles in 9 mo. The results are discussed in relation to other Dynastid palm pests and coconut protection in Ivory Coast.

Animals↗
PubMed1990

Effects of heavy metal ions on intercellular communication in Syrian hamster embryo cells.

Several heavy metal salts [NiSO4, Cd(CH3COO)2, Pb(CH3COO)2, K2CrO4, CrCl3] were examined for their effects on intercellular communication in primary Syrian hamster embryo (SHE) cells and in the 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-sensitive SHE cell line BPNi. Two exposure regimes were used: the standard regime where the exposure occurred after the cells had grown to confluence; and a non-standard regime where a high number of cells were seeded in a medium containing the metal salts. None of the chemicals were potent inhibitors of communication, i.e. effects were only found at concentrations that were non-compatible with long-term survival of the cells. NiSO4 inhibited communication in both regimes and in both cell types, but the effect was more pronounced for BPNi cells in the non-standard regime. K2CrO4 inhibited communication in the non-standard regime in both cell types, but significantly increased communication in the standard regime in BPNi cells. Similar effects were not found with CrCl3 or KCl. Thus, they were due to the properties of the CrO4(2-) ion. K2CrO4 upregulated communication in TPA-exposed BPNi cells. A high concentration of SO4(2-) did not influence the K2CrO4 inhibition in the non-standard regime, but it significantly inhibited the K2CrO4-induced increase in communication in the standard regime in BPNi cells. This suggests that K2CrO4 acts through two different mechanisms in the two exposure regimes. The CrO4(2-)-sensitive site that causes enhancement of communication in the standard regime is probably intracellular, while the site causing CrO4(2-) inhibition in the formation of gap junctional communication in the non-standard regime is most likely to be extracellular.

Animals↗
PubMed2001

Prolonged antiplatelet therapy to prevent late thrombosis after intracoronary gamma-radiation in patients with in-stent restenosis: Washington Radiation for In-Stent Restenosis Trial plus 6 months of clopidogrel (WRIST PLUS).

BACKGROUND: Intracoronary gamma-radiation reduces recurrent in-stent restenosis. Late thrombosis (>30 days after radiation therapy) is identified as a serious complication. The Washington Radiation for In-Stent Restenosis Trial (WRIST) PLUS, which involved 6 months of treatment with clopidogrel and aspirin, was designed to examine the efficacy and safety of prolonged antiplatelet therapy for the prevention of late thrombosis. METHODS AND RESULTS: A total of 120 consecutive patients with diffuse in-stent restenosis in native coronary arteries and vein grafts with lesions <80 mm underwent percutaneous coronary transluminal angioplasty, laser ablation, and/or rotational atherectomy. Additional stents were placed in 34 patients (28.3%). After the intervention, a closed-end lumen catheter was introduced into the artery, a ribbon with different trains of radioactive (192)Ir seeds was positioned to cover the treated site, and a dose of 14 Gy to 2 mm was prescribed. Patients were discharged with clopidogrel and aspirin for 6 months and followed angiographically and clinically. All patients but one tolerated the clopidogrel. The late occlusion and thrombosis rates were compared with the gamma-radiation-treated (n=125) and the placebo patients (n=126) from the WRIST and LONG WRIST studies (which involved only 1 month of antiplatelet therapy). At 6 months, the group receiving prolonged antiplatelet therapy had total occlusion and late thrombosis rates of 5.8% and 2.5%, respectively; these rates were lower than those in the active gamma-radiation group and similar to those in the placebo historical control group. CONCLUSIONS: Six months of clopidogrel and aspirin and a reduction in re-stenting for patients with in-stent restenosis treated with gamma-radiation is well tolerated and associated with a reduction in the late thrombosis rate compared with a similar cohort treated with only 1 month of clopidogrel and aspirin.

Aged↗
PubMed1999

Inhibitory effect of Trapidil on the proliferation of bovine corneal fibroblasts in vitro.

BACKGROUND: In order to develop new strategies for the pharmacological modulation of posttraumatic and postsurgical wound healing of the corneal stroma, the effect of Trapidil, a competitive platelet-derived growth factor (PDGF) antagonist, on the proliferation of cultured bovine stromal fibroblasts (BSF) was investigated. METHODS: BSF, obtained from explant cultures, were seeded at a cell density of 100/mm2. The effect of various concentrations of Trapidil on cell viability and cell proliferation was determined using three different culture conditions: (1) serum-free medium (WM/F12), (2) serum-containing medium (WM/F12 + 10% FCS), and (3) serum-free medium + 50 ng/ml PDGF-BB. Trapidil was added in concentrations ranging from 100 micrograms/ml to 400 micrograms/ml. Cell numbers were determined 2 and 5 days after addition of Trapidil, using a computer-based cell-counting system. Cell viability was evaluated morphologically and by means of a repopulation assay. RESULTS: Addition of Trapidil (100-400 micrograms/ml) led to a significant, dose-dependent inhibition of both serum- and PDGF-BB-induced proliferation of BSF. In contrast, treatment of quiescent BSF, cultured in serum-free medium, did not result in a significant reduction of cell number. No cytotoxic effects were observed. CONCLUSION: The results of the present study demonstrate an inhibitory effect of Trapidil on the proliferation of BSF. It can be assumed that application of Trapidil might be a useful tool in the prevention of corneal complications after trauma (e.g., scarring, astigmatism and--with respect to photorefractive procedures--formation of haze and regression of the refractive effect).

Animals↗
PubMed2002

Twelve versus six months of clopidogrel to reduce major cardiac events in patients undergoing gamma-radiation therapy for in-stent restenosis: Washington Radiation for In-Stent restenosis Trial (WRIST) 12 versus WRIST PLUS.

BACKGROUND: Intracoronary gamma-radiation reduces recurrent in-stent restenosis (ISR). Late thrombosis was attenuated with 6 months of aspirin and clopidogrel. We aimed to find out whether 12 months of aspirin plus clopidogrel is superior to a strategy of 6 months after radiation therapy for patients with ISR. METHODS AND RESULTS: One hundred twenty consecutive patients with diffuse ISR in native coronaries and vein grafts with lesions <80 mm in length underwent PTCA, laser ablation, or rotational atherectomy. Additional stents were placed in 39 patients (33%). After the intervention, a ribbon with different trains of radioactive 192Ir seeds was positioned to cover the treated site, and a dose of 14 Gy to 2 mm was prescribed. Patients were discharged with clopidogrel and aspirin for 12 months and followed up clinically. The cardiac clinical event rates at 15 months were compared with the gamma-treated (n=120) patients of the WRIST PLUS study (only 6 months of antiplatelet therapy). Whereas the late thrombosis rates were similar (3.3% for the group given 12 months of antiplatelet therapy versus 4.2% for the group given 6 months, P=0.72), the group treated with 12 months of antiplatelet therapy had a rate of 21% for major adverse cardiac events and 20% for target-lesion revascularization compared with 36% (P=0.01) and 35% (P=0.009), respectively, in patients who were treated with only 6 months of clopidogrel. CONCLUSIONS: Twelve months of clopidogrel is superior to 6 months in reducing overall major cardiac events and revascularization rates at 15 months for patients with ISR treated with gamma-radiation. At least 12 months of clopidogrel therapy should be recommended for patients undergoing radiation therapy for ISR.

Aspirin↗