Quantitative spatial distribution of sirolimus and polymers in drug-eluting stents using confocal Raman microscopy.

Raman spectroscopy was used to differentiate each component found in the CYPHER Sirolimus-eluting Coronary Stent. The unique spectral features identified for each component were then used to develop three separate calibration curves to describe the solid phase distribution found on drug-polymer coated stents. The calibration curves were obtained by analyzing confocal Raman spectral depth profiles from a set of 16 unique formulations of drug-polymer coatings sprayed onto stents and planar substrates. The sirolimus model was linear from 0 to 100 wt % of drug. The individual polymer calibration curves for poly(ethylene-co-vinyl acetate) [PEVA] and poly(n-butyl methacrylate) [PBMA] were also linear from 0 to 100 wt %. The calibration curves were tested on three independent drug-polymer coated stents. The sirolimus calibration predicted the drug content within 1 wt % of the laboratory assay value. The polymer calibrations predicted the content within 7 wt % of the formulation solution content. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra from five formulations confirmed a linear response to changes in sirolimus and polymer content.

Stent-based delivery of sirolimus reduces neointimal formation in a porcine coronary model.

BACKGROUND: The purpose of this study was to determine the efficacy of stent-based delivery of sirolimus (SRL) alone or in combination with dexamethasone (DEX) to reduce in-stent neointimal hyperplasia. SRL is a potent immunosuppressive agent that inhibits SMC proliferation by blocking cell cycle progression. METHODS AND RESULTS: Stents were coated with a nonerodable polymer containing 185 microgram SRL, 350 microgram DEX, or 185 microgram SRL and 350 microgram DEX. Polymer biocompatibility studies in the porcine and canine models showed acceptable tissue response at 60 days. Forty-seven stents (metal, n=13; SRL, n=13; DEX, n=13; SRL and DEX, n=8) were implanted in the coronary arteries of 16 pigs. The tissue level of SRL was 97+/-13 ng/artery, with a stent content of 71+/-10 microgram at 3 days. At 7 days, proliferating cell nuclear antigen and retinoblastoma protein expression were reduced 60% and 50%, respectively, by the SRL stents. After 28 days, the mean neointimal area was 2.47+/-1.04 mm(2) for the SRL alone and 2.42+/-1.04 mm(2) for the combination of SRL and DEX compared with the metal (5.06+/-1.88 mm(2), P<0.0001) or DEX-coated stents (4.31+/-3.21 mm(2), P<0.001), resulting in a 50% reduction of percent in-stent stenosis. CONCLUSIONS: Stent-based delivery of SRL via a nonerodable polymer matrix is feasible and effectively reduces in-stent neointimal hyperplasia by inhibiting cellular proliferation.

Heparin-coated stents.

Stenting has revolutionized the field of interventional cardiology. However, early studies revealed a high incidence of thrombotic occlusion of the stent and significant bleeding complications resulting from the use of intensive anticoagulation after implantation. One of the strategies used to reduce stent thrombosis and hemorrhagic complications has been to decrease the thrombogenicity of the stent surface. For this purpose, a unique heparin surface patented by Carmeda AB (Stockholm, Sweden)--the Carmeda BioActive Surface (CBAS)--has been coated onto Cordis (Johnson & Johnson) stents. Preclinical evaluations of the thromboresistance of heparin-coated stents and clinical studies of heparin-coated stents in a variety of clinical settings are discussed.

Healthy Municipios in Latin America.

PIP: This article describes the Healthy Municipios movement in Latin America and gives examples of some PAHO projects that could become demonstration projects. The Healthy Municipios movement was established in the early 1990s. The movement aims to promote healthy municipalities according to objectives set forth in the 1987 Ottawa Charter on Health Promotion, the 1992 Declaration of Bogota, and the 1993 Caribbean Health Promotion Charter. The movement is a joint effort of government, the health sector, and the community in promoting health locally. Key features of the movement are its creativity, variety, political strength, and adaptation to local conditions. Technical cooperation serves the purpose of facilitating information exchange and promotes the use of modern techniques of analysis and scientific and technical information. All projects shared the following common features: initiation by the local community with strong political commitment, intersectoral organizational structure, widespread community mobilization and participation, problem solving activities, and a recognizable leader. Pioneering projects include the Comprehensive Project for Cienfuegos, Cuba; the Health Manizales, Colombia; the Network in Mexico; Baruta and El Hatillo, Venezuela; Valdivia, Chile; and San Carlos Canton, Costa Rica. It is concluded that these projects and most others aim to assure equity. These efforts are important for placing health on the political agenda and implementing healthy policies. The Valdivia project, for example, serves a population of about 120,000 in the urban city of Valdivia, the semi-urban area, and rural areas. The project was officially sanctioned by the President of Chile on World Health Day in 1993. Progress was reported in mass communication and school-based programs. Attention was directed also to prevention of risk factors for noncommunicable diseases and to the problem of traffic accidents.^ieng

Healthy municipios in Latin America

The health municipios strategy in Latin America is helping to promote new social pacts in the search for solutions to problems affecting health and well-being; to strengthen the principles of solidarity; and, above all, to find a means of achieving equity. Through this movement, the health sector is bolstering its leadership capability by putting health on the political agenda. In the process, the organization services is being improved and the formulation and implementation of healthy poblic policies is being advanced. The political, financial, and technical challenges are great, but is they can be met, the healthy municipios movement will contribute to building a culture of health through the promotion of healthy lifestyles and to strengthening democratic processes and fostering good citizenship

Healthy municipios in Latin America

The health municipios strategy in Latin America is helping to promote new social pacts in the search for solutions to problems affecting health and well-being; to strengthen the principles of solidarity; and, above all, to find a means of achieving equity. Through this movement, the health sector is bolstering its leadership capability by putting health on the political agenda. In the process, the organization services is being improved and the formulation and implementation of healthy poblic policies is being advanced. The political, financial, and technical challenges are great, but is they can be met, the healthy municipios movement will contribute to building a culture of health through the promotion of healthy lifestyles and to strengthening democratic processes and fostering good citizenship

Paper prepared for the Internatonal Conference on Healthy and Ecological Cities, Madrid, 22-25 March 1995

Diabetes in the Americas.

Diabetes mellitus is an important cause of disability and death throughout the Americas. Of the three main types (insulin-dependent, noninsulin-dependent, and malnutrition-related), virtually all cases in the Americas are either insulin-dependent (generally assessed in terms of incidence and usually occurring in subjects under 30) or noninsulin-dependent (generally assessed in terms of prevalence and usually occurring in subjects over 30). Data on noninsulin-dependent diabetes mellitus (NIDDM) in various parts of the Americas point to prevalences ranging from 1.4% (among the Mapuche Indians in Chile) to 14.1% (among residents of Mexico City). However, the use of different methods and standards to gather and analyze these data renders comparison of the NIDDM situations in different countries uncertain. A fair amount of comparable data on insulin-dependent diabetes mellitus (IDDM) have been gathered in various countries of the Region. These point to marked differences in annual incidence--ranging from 0.7 cases per 100,000 in Peru to 27 among males on Prince Edward Island, Canada--that have not been adequately explained, underlining the need for additional comparable data. Considering the seriousness of the disease, it is important to know how many people have and develop diabetes, so as to be able to take preventive and therapeutic measures and guide public health actions. Hence, further cooperation directed at effective standardization of procedures and goals is indicated. Such cooperation, which should also come to include standardized national and hemispheric diabetes programs, must be achieved in accordance with the resources available to each country.

Immobilization of poly(ethylene glycol) onto a poly(vinyl alcohol) hydrogel: 2. Evaluation of thrombogenicity.

Immobilized polyethylene glycol (PEG) reduced the amount of bovine serum albumin (BSA) adsorbed on polyvinyl alcohol (PVA) hydrogel, but did not reduce the platelet reactivity of the hydrogel surface. PEG, molecular weight (MW) 2000 or 5000, with or without a monomethoxy end group, was covalently bound to glutaraldehyde-crosslinked PVA either through a cyclic acetal or an urethane functional group with a surface coverage of 70% (as measured by x-ray photoelectron spectroscopy [XPS]). Immobilization of monomethoxy-PEG via a cyclic acetal reduced BSA adsorption to PVA from 11 +/- 2 nmol/m2 to 3.9 +/- 0.3 nmol/m2 and 3.3 +/- 0.3 nmol/m2 for MW 2000 and 5000, respectively. Similarly, urethane bound PEG reduced adsorption to 3.5 +/- 1.6 nmol/m2 for MW 2000 and 5.4 +/- 1.0 nmol/m2 for MW 5000. Whole blood clotting times of PVA (using a Chandler loop) were not affected by covalently linked PEG, although the initial rate of thrombin generation at the surface, measured using a fluorogenic substrate, was marginally reduced; a rate constant of 4.2 +/- 0.1 cm/sec and 3.5 +/- 0.1 cm/sec were obtained for MW 2000 and 5000, respectively, compared to 5.6 +/- 1.0 cm/sec for PVA. Ex vivo evaluation using a canine arteriovenous shunt revealed that the hydrogel, with or without bound PEG, reduced circulating platelet levels by 35-70% after 4 days. The initial fractional rate of platelet destruction determined from measurement of platelet cyclooxygenase activity, indicated that cyclic acetal or urethane bound PEG of either molecular weight had no effect on platelet consumption produced by PVA.(ABSTRACT TRUNCATED AT 250 WORDS)

Does polyethylene oxide possess a low thrombogenicity?

Because of the 'bland' nature of polyethylene oxide towards proteins and cells, considerable effort has been devoted to preparing surfaces rich in polyethylene oxide, using block copolymers, surface immobilization or other methods. It is clear that these modifications result in reduced levels of cell (including platelet) adhesion and protein adsorption, when compared to unmodified and typically hydrophobic substrates. It is far less clear whether the reduced adhesion or adsorption is due specifically to the thermodynamic effects of polyethylene oxide or to the increase in surface hydrophilicity after its immobilization. Even more so, it is unclear whether the reduction in such parameters is evidence of a reduced thrombogenicity.

Heparin-poly(ethylene glycol)-poly(vinyl alcohol) hydrogel: preparation and assessment of thrombogenicity.

Heparin was immobilized on to poly(vinyl alcohol) hydrogel (PVA) through the free isocyanate end-group on a poly(ethylene glycol) (PEG2000) which had been previously covalently linked to the hydrogel via a urethane moiety. The intention was to reduce the platelet reactivity of the PVA while also suppressing fibrin formation. Elemental nitrogen analysis revealed that the total amount of bound heparin was 19 +/- 7 mumol/g of dried gel. An increase in the in vitro whole blood clotting time of PVA was observed. This was attributed to bound heparin, as the elution rate of heparin from the gel (23 pmol/m2 min) was too low to produce a significant bulk concentration to interfere with fibrin formation. Ex vivo assessment using a chronic canine A-V shunt showed that the bound heparin hydrogel had no effect on the drop in the number of platelets induced by PVA hydrogel, but increased the fractional rate of platelet destruction from approximately 0.35/d to an average value of 0.42/d.

Immobilization of prostaglandin PGF2 alpha on poly(vinyl alcohol).

Prostaglandin PGF2 alpha was immobilized onto a poly(vinyl alcohol) hydrogel (PVA) by reaction of a PGF2 alpha-polylysine adduct with glutaraldehyde. The PGF2 alpha-polylysine adduct was prepared by carbodiimide activation of the carboxyl group of PGF2 alpha followed by coupling to the lysine. The adduct was separated from the unreacted PGF2 alpha by dialysis and the purified product was found to contain congruent to 44 mol of PGF2 alpha/mol of adduct involving congruent to 40% of the amines of the polylysine. The adduct was bound to PVA by reacting with an excess of glutaraldehyde at 0 degrees C, followed by cross-linking of the PVA to a gel at 35-37 degrees C. The PGF2 alpha of the adduct was found to retain congruent to 40% of its biological activity on a molar basis in a smooth muscle cell contraction assay, but its activity immobilized to PVA was not determined. Spectroscopically, infrared nuclear magnetic resonance (IR/NMR), the PGF2 alpha appeared identical to the native molecule, except for the amide bond at its carboxylic acid, suggesting that the reactions were very gentle and that other biomolecules could be incorporated into the gel without loss of activity.

Studies of the mode of action of antitumor triazenes and triazines. 6. 1-Aryl-3-(hydroxymethyl)-3-methyltriazenes: synthesis, chemistry, and antitumor properties.

1-Aryl-3-(hydroxymethyl)-3-alkyltriazenes [ArN = NN(CH3)CH2OH] have been synthesized by diazonium coupling to the carbinolamine (RNHCH2OH), generated in situ from the alkylamine and formaldehyde mixtures. The (hydroxymethyl)triazene structure has been confirmed by IR, NMR, and mass spectral analysis and also by the preparation of a crystalline benzoate derivative. The mass spectra of the (hydroxymethyl)triazenes suggest that they fragment by loss of formaldehyde to give the methyltriazene, which is also the product of hydrolysis in solution. The degradation of the (hydroxymethyl)triazenes in solution has been followed by UV spectroscopy and by HPLC analysis, and the half-lives were determined under a variety of conditions. The half-lives of the corresponding methyl- and (hydroxymethyl)triazenes are very similar. Both methyl- and (hydroxymethyl)triazenes decompose on silica plates during TLC analysis to give products consistent with known diazo-migration reactions. The (hydroxymethyl)triazenes have pronounced antitumor activity against the TLX5 tumor in vivo; in vivo-in vitro bioassay experiments suggest that the (hydroxymethyl)triazenes exert their in vivo antitumor activity via the degradation product, the alkyltriazene.

Triazene metabolism. II. Transportability and enzyme inhibitory characteristics of metabolites of antitumor dimethyltriazenes.

A series of dimethyltriazenes (Ar . N==N . NMe2), monomethyltriazenes (Ar . N==N . NH . Me), and triazene carbinolamines (Ar . N==N . NMe . CH2OH) have been studied for their inhibitory effects on the enzyme, hog liver esterase (EC 3.1.1.1). p-Nitrophenyl acetate was used as the model substrate and the rate of hydrolysis was followed spectrophotometrically at 400 nm, the absorption maximum of the p-nitrophenylate ion. Only triazenes with an ester group in the aryl moiety exhibited significant inhibition. Preincubation of the enzyme with the monomethyltriazene (McO2C . C6H4 . N==N . NHMe) or the methyloltriazene (MeO2C . C6H4 . N==NMe . CH2OH) gave enhanced inhibition, which was not observed when the dimethyltriazene (MeO2C . C6H4 . N==N . NMe2) was preincubated with the enzyme. Inhibition of enzyme activity by the monomethyltriazene was shown to be essentially irreversible, whereas the model substrates, methyl benzoate and methyl p-aminobenzoate, gave reversible inhibition in the same assay. The inhibition by the N-methyloltriazene was only partially reversible. . The results are discussed with relevance to the role of the monomethyltriazenes and N-methyloltriazenes as possible transportable metabolites of the antitumour dimethyltriazenes.

Composition of tobaccos from countries with high and low incidences of lung cancer. I. Selenium, polonium-210, Alternaria, tar, and nicotine.

Tobaccos from countries with high and low incidences of lung cancer were analyzed. Tobacco concentrations of polonium-210 were similar in cigarettes from high- and low-incidence countries, as were levels of cigarette smoke tar and nicotine. Tobaccos from low-incidence countries had significantly lower Alternaria spore counts. Mean selenium concentrations of tobaccos from the high-incidence countries (0.16 +/- 0.05 micrograms/g) were significantly lower than those of tobaccos from the low-incidence countries (0.49 +/- 0.22 micrograms/g).