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Biomedical subjects

Kandice Kottke-Marchant

Publications and source records attributed to Kandice Kottke-Marchant.

At least 19 recordsLinked to original sources
PubMed2006

Lack of effect of enteric coating on aspirin-induced inhibition of platelet aggregation in healthy volunteers.

BACKGROUND: Aspirin inhibits platelet aggregation and is widely used in the treatment of cardiovascular disease. Some individuals are less responsive to aspirin's antiplatelet effect, a phenomenon termed aspirin resistance. It is not known whether the antiplatelet effect is fully preserved with the enteric-coated (EC) formulation. METHODS: We performed a prospective randomized trial of 50 healthy volunteers using a crossover design to compare the EC with the standard aspirin formulations. The subjects received a 7-day course of each aspirin formulation (81-mg) (Bayer Corporation, Morristown, NJ) separated by a 3-week washout period. Platelet function was measured before and after each course using optical aggregometry (with arachidonic acid and adenosine diphosphate as agonists) and a point-of-care platelet assay. RESULTS: The assays were reproducible, and the variation in baseline platelet function was small to moderate between the subjects. There was no difference in the extent of platelet inhibition between the EC and standard formulations with any of the 3 assays. With the point-of-care platelet assay, the mean aspirin effect favoring the standard formulation (more aggregation inhibition) compared with the EC formulation was 1.6% +/- 15.8% (P = .60 for difference between the formulations). The corresponding optical aggregometry values were -3.4% +/- 39.5% (P = .97) and -1.4% +/- 16.6% (P = .75) for arachidonic acid and adenosine diphosphate, respectively. CONCLUSIONS: Compared with standard aspirin, EC aspirin appears to exhibit similar inhibition of platelet aggregation in healthy volunteers. Furthermore, point-of-care platelet assessment correlated well with the gold standard of laboratory-based optical platelet aggregometry.

Adult↗
PubMed2005

Aspirin resistance and a single gene.

This study examined the association of single nucleotide polymorphisms in 4 candidate genes in a cohort of subjects with aspirin resistance. Aspirin resistance was significantly associated with genetic variation in the platelet surface adenosine 5-diphosphate receptor gene P2Y1.

Alleles↗
PubMed2005

Molecular genetic testing of polymorphisms associated with venous thrombosis: a review of molecular technologies.

The growing knowledge of genetic polymorphisms predisposing to venous thrombosis has increased the demand for genetic testing of associated risk factors. This has prompted the need for simple, fast, reliable, and cost-effective genotyping methods for identification of those mutations. In the past decade, a large variety of DNA mutation analysis methods have been developed for detection of genetic variants associated with venous thrombosis, including PCR-based and PCR-independent technologies. Each of these technologies possesses unique advantages, but all have a common goal of simplifying and expediting mutation analysis. This review describes some of the commonly used technologies and commercially available platforms employed in clinical laboratories for genetic testing of thrombophilia. The choice of a technology for each individual laboratory would primarily depend on the specific requirements for the assay's accuracy, reliability, speed, throughput, and cost-effectiveness.

DNA Mutational Analysis↗
PubMed2005

RGD-modified liposomes targeted to activated platelets as a potential vascular drug delivery system.

Local drug delivery has become an important treatment modality for the prevention of thrombotic events following coronary angioplasty. In this study, we investigate the ability of liposomes bearing surface conjugated linear Arg-Gly-Asp (RGD) peptide (GSSSGRGDSPA) moieties to target and bind activated platelets, and the effect of such RGD-modified liposomes on platelet activation and aggregation. The binding of RGD-liposomes to human platelets was assessed by fluorescence microscopy, phase contrast microscopy and flow cytometry. The effect of RGD-modified liposomes on platelet activation and aggregation was investigated in vitro, with and without platelet agonists. RGD-liposomes were found to bind activated platelets at levels significantly greater than the control RGE-liposomes. The RGD-liposomes did not exhibit any statistically significant effect on platelet activation or aggregation. The results demonstrate the ability of the RGD-modified liposomes to target and bind activated platelets without causing significant platelet aggregation and suggests a feasible way for the development of a platelet-targeted anti-thrombogenic drug delivery system. Furthermore, the approach can be extended to the development of liposomes for other vascular targets, for application in drug delivery or gene therapy.

Blood Platelets↗
PubMed2005

LightTyper platform for high-throughput clinical genotyping.

DNA sequence variations due to single nucleotide changes or polymorphisms (SNPs) have demonstrated an association with certain diseases as causative agents or surrogate biomarkers. Identification and genotyping of SNPs requires reliable and robust technologies. Multiple genotyping platforms are available to detect SNPs. Although many of these platforms meet the requirements of the research environment, technologies have also emerged for high-throughput clinical genotyping as well. The LightTyper is one such platform, providing SNP identification by employing melting curve analysis of fluorescently labeled probes. The LightTyper has been used to identify SNPs associated with myocardial infarction, developing and validating assays for approximately 100 SNPs in 30 candidate genes. The LightTyper is also amenable to the use of assays already developed for the LightCycler, which is widely used in clinical laboratories. The initial experience presented here suggests the potential use of the LightTyper for high-throughput clinical genotyping.

Animals↗
PubMed2005

The role of aspirin in the prevention of thrombotic complications of thalidomide and anthracycline-based chemotherapy for multiple myeloma.

OBJECTIVE: To study the efficacy of daily low-dose aspirin (81 mg orally) in decreasing the incidence of venous thromboembolic events (VTEs) in patients with multiple myeloma receiving pegylated doxorubicin, vincristine, and decreased-frequency dexamethasone, plus thalidomide (DVd-T). PATIENTS AND METHODS: In this phase 2 clinical trial of DVd-T, conducted by the Cleveland Clinic Foundation from August 2001 to October 2003, 105 patients were enrolled. The first 35 patients experienced increased numbers of VTEs. von Willebrand levels and platelet aggregation to ristocetin before and after treatment with DVd-T increased significantly, suggesting a pathophysiology involving platelet-endothelial interaction. Aspirin was added to the regimen, thus generating 3 patient groups: group 1 received aspirin from the start of DVd-T treatment before the study began (58 patients), group 2 received aspirin after the start of DVd-T treatment and after the study began (26 patients), and group 3 did not receive daily low-dose aspirin during the study (19 patients). Two patients being treated with warfarin for other indications were excluded from the study. The primary end point for this study was the incidence of VTE in the form of either deep venous thrombosis or pulmonary embolism. Secondary end points were the time to the first VTE, time to the composite end point of death or first VTE, and incidence of bleeding complications. RESULTS: After a median follow-up of 24 months, on an intent-to-treat basis, 26 posttreatment VTEs occurred after a median of 90 days, with 19% occurring in group 1, 15% in group 2, and 58% in group 3. Following multivariate time-to-event analysis, aspirin use continued to be associated with lower relative risk of VTE (hazard ratio, 0.22; confidence interval, 0.10-0.47; P<.001) and of the composite end point (hazard ratio, 0.28; confidence interval, 0.15-0.51; P<.001). CONCLUSION: Daily low-dose aspirin (81 mg orally) given to patients with newly diagnosed and relapsed/refractory multiple myeloma who were receiving DVd-T reduced the incidence of VTEs without an increase in bleeding complications.

Adult↗
PubMed2004

Extracellular matrix-like surfactant polymers containing arginine-glycine-aspartic acid (RGD) peptides.

We report on a novel series of biomimetic polymers exhibiting interfacial properties similar to the extracellular matrix. A series of well-defined surfactant polymers were synthesized by simultaneously incorporating arginine-glycine-aspartic acid (RGD) peptide, dextran oligosaccharide, and hexyl ligands with controlled feed ratios onto a poly(vinyl amine) (PVAm) backbone. The peptide sequence was H-GSSSGRGDSPA-NH(2) (Pep) having a hydrophilic extender at the amino terminus and capped carboxy terminus. The peptide-to-dextran (Pep:Dex) ratios were varied to create surfactants having 0, 25, 50, 75, and 100 mol-% peptide relative to dextran. The surfactants were characterized by IR, NMR and atomic force microscopy (AFM) for composition and surface active properties. AFM confirmed full surface coverage of PVAm(Pep)(100%) on graphite, and supported the mechanism of interdigitation of hexyl ligands between surfactant molecules within a specified range of hexyl chain densities. the attachment and growth of human pulmonary artery endothelial cells on the PVAm(Pep)(100%) surface was identical to the fibronectin positive control. Cell adhesion decreased dramatically with decreasing peptide density on the surfactant polymers. Molecular model of a peptide surfactant polymer, consisting of poly(vinyl amine) backbone with peptide, dextran oligosaccharide and hexyl branches coupled to the polymer chain.

Absorption↗
PubMed2003

Biometric surfactant polymers designed for shear-stable endothelialization on biomaterials.

We have developed a series of extracellular matrix (ECM)-like biomimetic surfactant polymers to improve endothelial cell adhesion and growth on vascular biomaterials. These polymers provide a single-step procedure for modifying the surface of existing biomaterials and consist of a poly(vinyl amine) (PVAm) backbone with varying ratios of cell-binding peptide (RGD) to carbohydrate (maltose), ranging from 100% RGD:0% maltose to 50% RGD:50% maltose. Three biomimetic surfaces, as well as a fibronectin (FN)-coated glass surface were seeded at confluence with human pulmonary artery endothelial cells (HPAECs) and exposed to shear stresses ranging from 0-40.6 dyn/cm2 for periods of 2 h and 6 h. Surfaces were examined for HPAEC coverage and cytoskeletal arrangement as a function of time and shear stress. In general, after 6 h of shear exposure, EC retention on 100% RGD > FN > 75% RGD > 50% RGD. The 100% RGD surface maintained more than 50% of its initial EC monolayer at low to moderate shear stresses whereas all other surfaces dropped to approximately 40% or less in the same shear stress range. The most stable surface, 100% RGD, showed a significant increase in cytoskeletal organization at all shear stresses greater than 2.5 dyn/cm2. In contrast, there was no real change in cytoskeletal organization on the FN surface, and there was a decrease on the 75% RGD surface over time. These results indicate that increasing surface peptide density can control EC shear stability. Furthermore, improved shear stability increases with increasing peptide density and is related to the EC's ability to reorganize its cytoskeleton.

Biocompatible Materials↗
PubMed2003

A prospective, blinded determination of the natural history of aspirin resistance among stable patients with cardiovascular disease.

OBJECTIVES: This study was designed to determine if aspirin resistance is associated with clinical events. BACKGROUND: Aspirin resistance, defined by platelet function testing and presumed clinical unresponsiveness to aspirin, has been previously reported by our group and others. However, little information exists linking the laboratory documentation of aspirin resistance and long-term clinical events. METHODS: We prospectively enrolled 326 stable cardiovascular patients from 1997 to 1999 on aspirin (325 mg/day for > or =7 days) and no other antiplatelet agents. We tested for aspirin sensitivity by optical platelet aggregation using adenosine diphosphate (ADP) and arachidonic acid (AA). The primary outcome was the composite of death, myocardial infarction (MI), or cerebrovascular accident (CVA). Mean follow-up was 679 +/- 185 days. Aspirin resistance was defined as a mean aggregation of > or =70% with 10 microM ADP and > or =20% with 0.5 mg/ml AA. RESULTS: Of the patients studied, 17 (5.2%) were aspirin resistant and 309 (94.8%) were not aspirin resistant. During follow-up, aspirin resistance was associated with an increased risk of death, MI, or CVA compared with patients who were aspirin sensitive (24% vs. 10%, hazard ratio [HR] 3.12, 95% confidence interval [CI] 1.10 to 8.90, p = 0.03). Stratified multivariate analyses identified platelet count, age, heart failure, and aspirin resistance to be independently associated with major adverse long-term outcomes (HR for aspirin resistance 4.14, 95% CI 1.42 to 12.06, p = 0.009). CONCLUSIONS: This study demonstrates the natural history of aspirin resistance in a stable population, documenting a greater than threefold increase in the risk of major adverse events associated with aspirin resistance.

Adult↗
PubMed2003

Lysophosphatidylcholine regulates human microvascular endothelial cell expression of chemokines.

The role of lysophosphatidylcholine (LPC) in the induction of MCP-1, IL-8 and RANTES, which are chemotactic factors to monocytes, neutrophils and lymphocytes, respectively, by human vascular endothelial cells (EC), was examined. LPC induced the expression of MCP-1 and IL-8 in a concentration- and time-dependent manner in microvascular EC (MVEC) and in large vessel EC from aorta, pulmonary artery and umbilical vein. LPC also induced RANTES in MVEC but not in large vessel EC. Signaling pathways responsible for LPC induction of chemokines were examined in MVEC. LPC and TNFalpha, a cytokine secreted in sites of inflammation, additively stimulated RANTES expression. LPC did not augment TNFalpha induction of MCP-1 or IL-8. A platelet-activating factor receptor antagonist (BN52021) failed to block LPC induction of MVEC chemokines, but the G(i)-protein inhibitor pertussis toxin partially blocked LPC induction of RANTES and IL-8. LPC activated multiple kinases in MVEC; it increased the phosphorylation of ERK1/2, AKT and p38 MAP kinase in a time-dependent manner. An inhibitor of the MAPK/ERK pathway, PD98059, blocked the phosphorylation of ERK1/2 and RANTES induction by LPC, but augmented IL-8 induction. LY294002, a specific inhibitor of phosphoinositide 3 kinase (PI3 kinase), blunted the phosphorylation of AKT and inhibited LPC induction of RANTES more strongly than IL-8. Inhibition of p38 MAP kinase pathway by SB202190 also blocked LPC-induced expression of IL-8 and RANTES. Our results suggest that LPC induction of chemokines in MVEC is distinct from that in large vessel EC, and required the activities of MAP kinases and PI3 kinase for the induction of RANTES and IL-8. We speculate that the presence of LPC, a bioactive lipid product of phospholipase A(2) (PLA(2)) and a constituent of oxidized low-density lipoprotein, can differentially influence the chemotaxis of particular leukocyte subpopulations during inflammation.

Aorta↗
PubMed2002

Elevated fibrinogen and homocysteine levels enhance the risk of mortality in patients from a high-risk preventive cardiology clinic.

Fibrinogen (Fib) plays an important role in platelet aggregation and thrombus formation, and homocysteine (tHcy) causes endothelial dysfunction and injury. Therefore, an interaction toward an enhanced risk of thrombotic events and consequent mortality might be expected in patients with both factors elevated. To determine whether patients exposed jointly to high Fib and high tHcy were at increased risk of mortality, we compared them with those with only one or neither risk factors elevated. Prevalence of coronary artery disease (cross-section) and short-term mortality (30+/-14 months) were assessed in 2084 patients with available baseline tHcy and Fib. Upper quartiles were used to define high tHcy (>14.2 micromol/L) and high Fib (>382 mg/dL). Cox models adjusting for Framingham risk score, creatinine, and coronary artery disease status were used to estimate the risk of high tHcy and high Fib and their combinations. Mean age of the patients was 56+/-12 years (35% women) with 71 (3.4%) recorded deaths. Risk-adjusted longitudinal models showed a hazard ratio of 2.14 (P=0.03) for isolated high tHcy, 2.28 (P=0.02) for isolated high Fib, and 3.29 (P<0.001) for both high tHcy and high Fib in comparison with neither risk factor high. Independence of each parameter and lack of synergism was found on longitudinal as well as cross-sectional analyses. Conjoint elevation of Fib and tHcy increased the risk of death by approximately 3-fold in three years. Although no significant interaction between Fib and tHcy was demonstrated, both provided independent information after adjustment for traditional risk factors.

Aged↗
PubMed2002

Fosinopril versus amlodipine comparative treatments study: a randomized trial to assess effects on plasminogen activator inhibitor-1.

BACKGROUND: ACE inhibitors and calcium antagonists may modulate fibrinolysis. We conducted a randomized controlled trial to assess the effects of these drugs on plasminogen activator inhibitor-1 (PAI-1) antigen, an inhibitor of fibrinolysis. METHODS AND RESULTS: Participants with hypertension and type 2 diabetes mellitus (n=96, 51% black) were randomized after an initial 4 weeks of placebo to double-blind 20 or 40 mg fosinopril or 5 or 10 mg amlodipine daily for 4 weeks in a fixed-dose regimen. After 4 weeks of placebo washout, the patients received 4 weeks of crossover treatments. After treatment with placebo, systolic and diastolic blood pressure were 143+/-2 and 86+/-1 mm Hg and plasma PAI-1 was 43.4+/-2.3 ng/mL. Amlodipine achieved a greater systolic and diastolic blood pressure reduction than fosinopril (10 mm Hg versus 8 mm Hg, P=0.029, and 5 mm Hg versus 3 mm Hg, P=0.040, respectively) but tended to increase PAI-1, whereas fosinopril tended to decrease PAI-1 (5.4+/-3.6 versus -3.8+/-2.5 ng/mL, P=0.045). The PAI-1 changes depended on drug dose (6.5+/-6.1 and 3.4+/-3.9 ng/mL with amlodipine 10 and 5 mg, respectively, and -0.4+/-3.1 and -7.4+/-4.0 ng/mL with fosinopril 20 and 40 mg, respectively, P for trend 0.024). No significant differences between fosinopril and amlodipine were found for short-term changes in tissue plasminogen activator antigen, fibrinogen, C-reactive protein, and interleukin-6. The findings were similar in black and white participants. CONCLUSIONS: Short-term treatment with fosinopril significantly reduced PAI-1 compared with amlodipine in a dose-dependent fashion. This effect, which was independent of blood pressure reduction, may account for the improved clinical outcomes achieved with ACE inhibitors compared with calcium antagonists.

Amlodipine↗
PubMed2002

Surface modification of liposomes for selective cell targeting in cardiovascular drug delivery.

Cardiovascular disease processes such as atherosclerosis, restenosis, and inflammation are typically localized to discrete regions of the vasculature, affording great opportunity for targeted pharmacological treatment. Liposomes are potentially advantageous targeted drug carriers for such intravascular applications. To facilitate their use as drug delivery vehicles, we have considered three components of liposome design: (i) identification of candidate cell surface receptors for targeting; (ii) identification of ligands that maintain binding specificity and affinity; and (iii) prevention of rapid nonspecific clearance of liposomes into the reticuloendothelial organs. In this report, we describe our work in developing liposomal surface modifications that address both targeting and clearance. An arginine-glycine-aspartic acid (RGD) containing peptide was used as a model ligand to target liposomes to the integrin GPIIb-IIIa on activated platelets. Additionally, oligodextran surfactants incorporated into liposomes provided insight into the effect of vesicle perturbations on liposome clearance, and the importance of molecular geometry in designing oligosaccharide surface modifications. Together these studies demonstrate the feasibility of using peptides to guide liposomes to desired receptors, and illustrate the influence of vesicle stability on liposome interactions in vivo. Furthermore, they underscore the importance of simultaneously considering both targeting specificity and vesicle longevity in the design of effective targeted drug delivery systems.

Animals↗