Aspirin reduces the prothrombotic activity of C-reactive protein.

AIM: C-reactive protein (CRP) is a risk marker and a potential modulator of vascular disease. Previous studies support a prothrombotic activity of CRP, with impaired thromboregulation. The present study examined the antithrombotic effect of aspirin in mice transgenic for human CRP (CRPtg mice). Mechanistic investigations further elucidated the effect of CRP on prostanoid metabolism in vivo and in vitro. METHODS AND RESULTS: Administration of aspirin (30 mg kg(-1) day(-1)) to CRPtg mice slowed the accelerated thrombosis after photochemical injury to the carotid (99 +/- 32 vs. 45 +/- 24 min and 75 +/- 23 vs. 82 +/- 26 min in wild-type mice vs. CRPtg mice, without and following aspirin treatment, respectively). Vascular injury modulated the expression of key pathways in prostanoid metabolism differently in CRPtg mice and wild-type mice. Suppression of cyclo-oxygenase 2 (COX-2)-derived metabolism with suppression of prostaglandin I2 (PGI2) synthase and PGI2 metabolism was recorded in the injured artery with increased thromboxane receptor expression. Aspirin therapy reduced the difference in PGI2 biosynthesis between CRPtg mice and wild-type mice. In vitro studies in human-derived cells further supported these findings. Incubation of human umbilical vein endothelial cells (HUVECs) with human recombinant CRP (5 microg mL(-1)) suppressed PGI2 synthase expression and significantly increased thromboxane receptor levels. Incubation of smooth muscle cells with CRP did not affect prostanoid expression. CONCLUSIONS: CRP modulates prostanoid metabolism to favor vascular occlusion. Elevated CRP levels might predispose to the cardiovascular hazard conferred by selective COX-2 inhibitors, and the risk mediated by CRP may be limited by aspirin.

Peritoneal macrophage depletion by liposomal bisphosphonate attenuates endometriosis in the rat model.

BACKGROUND: Activation of macrophages is central to the implantation of endometriosis (EM). We examined the hypothesis that macrophage depletion by intraperitoneal (IP) injection of liposomal alendronate (LA) could result in EM attenuation in a rat model, thus supporting the notion of the pivotal role of macrophages in EM pathology. METHODS: In this study, 90 rats were subjected to an EM model and were divided randomly into seven groups: five groups were treated by 4x once-weekly IP injections of LA (0.02, 0.1, 1, 5 or 10 mg/kg) and the other two groups received saline injections (control) or empty liposomes. Sham-operated rats also received empty liposomes. Depletion of circulating monocytes was determined by flow cytometry analyzes of blood specimens. Four weeks after the initial surgery, the number, size and weight of implants were recorded, adhesions were graded, macrophage infiltration was assessed and the peritoneal fluid was analyzed for monocyte chemotactic protein 1 (MCP-1) and tumor necrosis factor alpha (TNFalpha). RESULTS: Monocyte depletion following IP LA administration resulted in an inhibitory effect on the initiation and growth of EM implants, as expressed by implantation rate, adhesion scoring, implants' size and weight (>0.1 mg/kg LA, P < 0.05). Reduced numbers of infiltrating macrophages were observed in implants of the 1 mg/kg LA group. Peritoneal fluid MCP-1 levels were negatively correlated with LA dose (P < 0.001), whereas no significant correlation could be found for TNFalpha. CONCLUSIONS: Macrophage depletion using IP LA has been shown to effectively inhibit the initiation and growth of EM implants, in a rat EM model. The clear dose-response effect may be viewed as a confirmation of the validity of the concept and encourages further study.

Innate immunity has a dual effect on vascular healing: suppression and aggravation of neointimal formation and remodeling post-endotoxin challenge.

BACKGROUND: Inflammation is important to vascular repair following injury, modulating neointimal proliferation and remodeling. Previously, we have shown that a low-intensity inflammatory response aggravates neointimal formation following balloon and stent injury. The present study examined whether modulation of the extent and timing of nonspecific inflammation mediates the local vascular response in an additive unidirectional or rather a bidirectional fashion. METHODS AND RESULTS: Rabbits subjected to denudation and balloon injury of the iliac artery were treated with low (1 microg/kg) or high (100 microg/kg) doses of bacterial endotoxin (LPS) immediately after injury, or with early high-dose LPS administered 3 days prior to injury (preconditioning). Neointimal formation at 28 days was significantly increased in the low-dose group (0.537+/-0.059 mm(2)) as compared with controls (0.3+/-0.03 mm(2)). High-dose LPS did not significantly affect neointimal formation while early high dose significantly reduced neointima (0.296+/-0.033 and 0.194+/-0.025 mm(2), respectively, n=12-14/group). Arterial wall and systemically circulating interleukin-1 beta levels, and monocyte CD14 activation correlated with neointimal formation. Vascular remodeling was accelerated in animals treated with low- or high-dose LPS while not affected in the preconditioned group. Remodeling index inversely correlated with arterial matrix metalloproteinase-2 levels 6 days after injury. CONCLUSIONS: The extent and timing of nonspecific inflammation that is concurrent with vascular injury can determine different and opposite vascular repair patterns.

Raloxifene: cardiovascular considerations.

Ovarian hormone deficiency status is associated with increased cardiovascular morbidity and mortality, suggesting that estrogen might exhibit a favorable cardiovascular effect. Estrogen has a multitude of beneficial biological effects on surrogate markers of cardiovascular disease that may account for this hypothesis. However, none of the randomized trials already conducted with hormone replacement therapy showed overall benefit by means of reducing clinical ischemic cardiovascular events and/or suppressing atherogenesis. Moreover, the Women's Health Initiative study (WHI) has suggested a possible detrimental effect for hormone replacement therapy including increased cardiovascular morbidity, ovarian and breast cancer. Hence, any beneficial effect of estrogen must be carefully weighed against its carcinogenic properties together with its side effects. The need for a more efficient and specific molecule led to the development of the selective estrogen receptor modulators (SERMs). This new generation of drugs mimic the effect of estrogen in some tissues while antagonize several estrogen effects in other tissues. These unique properties offer the possibility to attain the beneficial effects of estrogen while avoiding its carcinogenic effect and the accompanying adverse reactions. Here we review the different effects of raloxifene- a protype second generation SERM on the cardiovascular system. We discuss raloxifene's role at different levels of the atherothrombotic cascade addressing each level separately; trying to clarify the net effect of raloxifene in modulating thrombosis in the arterial tree.

Formulation and delivery mode affect disposition and activity of tyrphostin-loaded nanoparticles in the rat carotid model.

Poor drug residence in the arterial wall hinders clinical implementation of local drug delivery strategies for the treatment of restenosis. A rat carotid model of vascular injury and intraluminal delivery of tyrphostin-containing polylactic acid (PLA) nanoparticles (NPs) were used to determine the relationship between residence properties and biological activity of different formulations and administration modes. The effects of delivery modes (denudation and delivery time) and formulation variables (adsorbed vs encapsulated drug, and NP size) on arterial drug/NP retention were examined. Antirestenotic effects of large (160 nm) and small (90 nm) tyrphostin-containing NPs, surface-absorbed tyrphostin, and systemic treatment were compared. Fluorescent NPs were used to study the spatial distribution of the carrier in the arterial wall. The decrease in arterial tyrphostin level over time fitted a biexponential model. Delivery time and pressure, endothelium integrity, particle size, and drug-polymer association affected local pharmacokinetics and the antirestenotic results after 14 days. The PLA-based tyrphostin NP formulation ensured a prolonged drug residence at the angioplasty site after single intraluminal application. Several readily adjustable formulation and procedural factors considerably modified arterial ingress of the drug-loaded NPs and governed their subsequent redistribution, tissue binding, elimination, and ensuing antirestenotic effect.

Viral neuroinvasion as a marker for BBB integrity following exposure to cholinesterase inhibitors.

Exposure to the nerve agent soman, an irreversible cholinesterase (ChE) inhibitor, results in changes in blood-brain barrier permeability attributed to its seizure-induced activity. However, smaller BBB changes may be independent of convulsions. Such minor injury may escape detection. A nonneuroinvasive neurovirulent Sindbis virus strain (SVN) was used as a marker for BBB permeability. Peripheral inoculation of mice with 2 x 10(3) plaque forming units (PFU) caused up to 10(5) PFU/ml viremia after 24 hours with no signs of central nervous system (CNS) infection and with no virus detected in brain tissue. Intra-cerebral injection of as low as 1-5 PFU of the same virus caused CNS infection, exhibited 5-7 days later as hind limb paralysis and death. Soman (0.1-0.7 of the LD50) was administered at peak viremia (1 day following peripheral inoculation). Sublethal soman exposure at as low as 0.1 LD50 resulted in CNS infection 6-8 days following inoculation in 30-40% of the mice. High virus titer were recorded in brain tissue of sick mice while no virus was detected in healthy mice subjected to the same treatment. No changes in the level of viremia or changes in viral traits were observed in the infected mice. The reversible anticholinesterases physostigmine (0.2 mg/kg, s.c.) and pyridostigmine (0.4 mg/kg, i.m.) injected at a dose equal to 0.1 LD50, induced similar results. Thus, both central and peripheral anticholinesterases (anti-ChEs) induce changes in BBB permeability sufficient to allow, at least in some of the mice, the invasion of this otherwise noninvasive but highly neurovirulent virus. This BBB change is probably due to the presence of cholinesterases in the capillary wall. SVN brain invasion served here as a highly sensitive and reliable marker for BBB integrity.

Acute myocardial infarction--a late complication of intracoronary stent placement.

BACKGROUND: Myocardial infarction (MI) as the first indication of postangioplasty restenosis is extremely rare, and it has been speculated that the fibroproliferative restenotic lesion is less likely to undergo plaque rupture than the lipid-laden native atherosclerotic lesion. HYPOTHESIS: The present study was designed to examine whether intracoronary stent implantation affects this course. METHODS: In all, 994 consecutive patients who underwent angioplasty and intracoronary stent implantation in our hospital were reviewed retrospectively for the occurrence of MI. RESULTS: Eight patients (0.8%), all male and hypertensive, aged 33-83 years, presented with an MI due to stent occlusion more than 30 days following stenting (range: 35-398 days). In two patients, MI occurred 3 and 5 h, respectively, following completion of a maximal high-level exercise test that was negative for ischemia. Angiography revealed complete occlusion or significant stenosis of the stent in all eight patients, with an obvious intimal dissection in either edge of the stent in six patients. Except for gender and hypertension, no correlation was found with other risk factors, vessel involved, initial angiographic results, or with stent design, diameter, or length. CONCLUSIONS: Myocardial infarction as a late complication of successful stent implantation occurred in 0.8% of our patients. This is only the lower bound of the estimated frequency for such an event. We hypothesize that the transition point between the relatively fixed stent and the normal artery is exposed to high deformation stress which makes it vulnerable to rupture and dissection. Strenuous exercise and hypertension may increase the deformation stress and the risk of intimal rupture.

Dehydroepiandrosterone selectively inhibits production of tumor necrosis factor alpha and interleukin-6 [correction of interlukin-6] in astrocytes.

Dehydroepiandrosterone (DHEA) is a native neurosteroid with immunomodulating activity. DHEA effectively protects animals from several viral, bacterial and parasitic infections and it was suggested that its age-associated decline is related with immunosenescence. In the present study we examined the ability of DHEA to inhibit the production of inflammatory mediators by mycoplasma-stimulated glial cells and to change the course of acute central nervous system (CNS) inflammatory disease in vivo. Addition of DHEA (10 microg/ml) markedly inhibited tumor necrosis factor alpha (TNFalpha) and interleukin-6 (IL-6) production (98 and 95%, respectively), whereas nitric oxide (NO) and prostaglandin E2 (PGE2) production was not affected. However, daily administration of 0.5 mg DHEA to mice or 5 mg to rats did not change the clinical outcome of experimental autoimmune encephalomyelitis (EAE).

A 42-year-old man with recurrent myocardial infarction and normal appearing coronary arteries.

We report the occurrence of a coronary mural thrombus and recurrent myocardial infarction in a patient with normal-appearing epicardial coronary arteries and small-vessel coronary artery disease. The current case emphasizes the importance of permanent medical treatment with anti-platelet and vasodilators in patients with small-vessel coronary artery disease.

Acute myocardical infarction due to delirium tremens.

A 36-year-old patient with normal-appearing coronary arteries suffered an acute Q-wave myocardial infarction during acute alcohol withdrawal and delirium tremens. Sympathetic hyperactivity with coronary spasm and increased platelet reactivity are probably the underlying mechanisms.

Pharmacodynamic and pharmacokinetic rationales for the development of an oral controlled-release amoxicillin dosage form.

The goal of this investigation was to develop an oral sustained-release formulation for amoxicillin that would maximize the duration of active drug concentration in the extracellular fluid, thus increasing the dosing interval while assuring antimicrobial activity. This rationale is based on the pharmacodynamic properties of the drug which is non- concentration dependent on the one hand, while requiring long exposure of the pathogen to the drug with minimal post-antibiotic effect on the other. Due to pharmacokinetic constraints, including short biological half-life and limited 'absorption window' (confined to the small intestine) with poor colonic absorption, the new matrix tablet formulation, composed of hydrophilic (hydroxypropyl methyl-cellulose) polymer, was designed to release 50% of its contents within the first 3 h and to complete the drug release process over 8 h (under in vitro conditions). The pharmacokinetics of the new formulation was evaluated in 12 healthy volunteers and compared to a conventional gelatin capsule with both formulations containing 500 mg amoxicillin. The plasma concentrations of active amoxicillin and penicilloic acid were determined by an HPLC method with a fluorometric detector. It was found that the area under the concentration-time curve and maximal serum amoxicillin concentrations following the sustained release preparation were lower than the immediate release formulation. However, the time over the required threshold concentrations, i.e. the minimal inhibitory concentration (MIC) as well as the more clinically relevant parameter--four times MIC of the drug against susceptible pathogens, was found to be maintained for significantly longer periods. The results suggest that in order to achieve a twice daily dosing regimen that will provide therapeutic concentrations for the whole 12 h dosing intervals, a larger dose of the new formulation should be given (e.g. 750 mg or even 1 g twice daily). This recommendation is based on the large interindividual differences of the extent of amoxicillin absorption found in this investigation, and is intended to assure that the 'poor' absorbers will also benefit from full antibiotic efficacy. This dosing regimen will lead to increased patient compliance and improved therapeutic outcome.

The influence of sequential annual vaccination and of DHEA administration on the efficacy of the immune response to influenza vaccine in the elderly.

The present study examined the effect of repeated vaccination and of dehydroepiandrosterone (DHEA) treatment on the immune response to influenza vaccine in elderly subjects. Seventy-one elderly volunteers, aged 61-89 years, enrolled in a prospective randomized, double-blind study to receive either DHEA (50 mg qd p.o. for 4 consecutive days starting 2 days before immunization) or placebo. Antibody response against the three strains of vaccine was measured before and 28 days after vaccination, and compared between previously vaccinated and non-vaccinated subjects. DHEA treatment did not enhance established immunity. A significant decrease in attainment of protective antibody titer (titer of 1:40 or greater) against A/Texas in subjects with non-protective baseline antibody titer was recorded following DHEA treatment compared to placebo (52 vs. 84%, P < 0.05). Post-immunization titers against influenza A strains were significantly higher in those subjects who were never immunized before. Additionally, post-vaccination protective titers against the A/Johannesburg strain were more prevalent in those subjects who were never vaccinated before. The results were not the same for anti-B/Harbin antibodies-repeated vaccination caused a non-significant increase in HI titer in previously vaccinated subjects.

Dehydroepiandrosterone treatment is not beneficial to the immune response to influenza in elderly subjects.

BACKGROUND: Dehydroepiandrosterone (DHEA) is a native steroid with an immunomodulating activity that was suggested to counter-regulate some phenomena of immunosenescence. Recently, it was shown to reverse the age-associated decline of immune response against influenza vaccine in aged mice. The present study was designed to evaluate the effect of DHEA on the immunization of elderly volunteers against influenza. METHODS: Seventy-one elderly volunteers age 61-89 yr were enrolled in a prospective randomized, double-blind study to receive either DHEA (50 mg qd p.o. for four consecutive days starting two days before immunization) or placebo. Antibody response to the vaccine was measured before and 28 days after vaccination. RESULTS: DHEA treatment significantly increased serum DHEA-sulfate (DHEA-S). No enhancement in established immunity was observed. A significant decrease in attainment of protective antibody titer (1:40 or higher) against the A/Texas strain in subjects with nonprotective baseline antibody titer was recorded following DHEA treatment compared with placebo (52% vs. 84%, P < 0.05). Baseline DHEA-S serum levels were inversely related to attainment of immunization in DHEA-treated subjects. Influenza-like morbidity during the winter was low in the study group with no difference between the DHEA and placebo groups. CONCLUSIONS: Although highly effective in aged rodents, a short course of DHEA treatment did not improve the age-related declined response to immunization against influenza in human subjects. Higher baseline DHEA-S levels are not predictive of better immunization against influenza in the elderly.

[Salbutamol intoxication].

A 20-year-old asthmatic woman who ingested 300 mg of salbutamol (Albuterol) and 30 g of paracetamol is presented. She had sinus tachycardia up to 160/min, hypotension (80/50 mmHg), tremor, hypokalemia (2.1 mEq/l) and hyperglycemia (12.1 mEq/l). Treatment was by gastric lavage, fluids, potassium and N-acetylcysteine. Symptoms resolved in 24 hours.

Tachycardia, orthostatic hypotension and profound weakness due to concomitant use of fluoxetine and nifedipine.

The use of the selective serotonin reuptake inhibitor fluoxetine is associated with only minor cardiovascular effects. However, due to a possible inhibitory effect on the metabolism of calcium channel blockers it may potentiate the activity of nifedipine, causing profound adverse cardiovascular effects. This report describes the appearance of profound weakness, orthostatic hypotension and tachycardia following the initiation of fluoxetine treatment in a nifedipine-treated 80-year-old patient.

Dehydroepiandrosterone (DHEA) increases production and release of Alzheimer's amyloid precursor protein.

Dehydroepiandrosterone (DHEA), the major secretory product of the human adrenal cortex, significantly declines with advanced age. We have previously demonstrated that DHEA prevents the reduction in non-amyloidogenic APP processing, following prolonged stimulation of the muscarinic receptor, in PC12 cells that express the ml acetylcholine-receptor. The present study examined whether this effect may be mediated via modulation of APP metabolism. It was found that DHEA treatment increases the content of membrane-associated APP holoprotein by 24%, and the accumulation of secreted APP in the medium by 63%. No increase in viable cell number nor in nonspecific protein production was observed in DHEA-treated cells. Thus, DHEA seems to increase specifically both APP synthesis and secretion. We propose that the age-associated decline in DHEA levels may be related to the pathological APP metabolism observed in Alzheimer's disease.

Dehydroepiandrosterone enhances influenza immunization in aged mice.

The effect of DHEA administration on the age-associated decline in immunity against influenza vaccine was studied. Increased humoral response was observed in 16- and 24-month-old mice immunized by live A/PR/8/34 (H1N1) influenza virus following DHEA treatment (a single injection adjacent to immunization). Furthermore, DHEA-treated mice demonstrated increased resistance to postvaccination intranasal challenge with live influenza virus. Thus, DHEA treatment overcomes the age-related defect in the immunity of old mice against influenza.

Dehydroepiandrosterone augments M1-muscarinic receptor-stimulated amyloid precursor protein secretion in desensitized PC12M1 cells.

Epidemiologic studies suggest that the age-related decline in dehydroepiandrosterone (DHEA) levels may be associated with Alzheimer's disease (AD). Cholinergic markers also decline with age, and are associated with AD pathology. Activation of m1AChR-transfected PC12 cells (PC12M1) with cholinergic agonists results in secretion of Alzheimer's beta-amyloid precursor protein (APP) which in turn reduces beta-amyloid production. This study examined whether DHEA affects APP processing in m1AChR-transfected PC12 cells. DHEA treatment did not significantly alter basal or m1AChR-stimulated APP secretion. However, DHEA (0.1 microM) significantly diminished the desensitization of APP secretion in cells exposed to carbachol for 24 h. The effect of DHEA on APP processing is probably not related to up-regulation of m1AChR or increased m1AChR-activated phosphoinositide hydrolysis since these parameters did not change following DHEA treatment. These findings imply a possible involvement of DHEA in APP processing. Thus, the age-associated decline in DHEA levels may contribute to decreased APP secretion and a consecutive increase in beta-amyloid deposition, which in turn may play a role in the development of AD.