Showing papers in "Current Pharmaceutical Design in 2004"

Natural and synthetic coumarin derivatives with anti-inflammatory/ antioxidant activities.

Abstract: Several natural products with a coumarinic moiety have been reported to have multiple biological activities. It is to be expected that, in a similar way to isomeric flavonoids, coumarins might affect the formation and scavenging of reactive oxygen species (ROS) and influence processes involving free radical-mediated injury. Coumarin can reduce tissue edema and inflammation. Moreover coumarin and its 7-hydroxy-derivative inhibit prostaglandin biosynthesis, which involves fatty acid hydroperoxy intermediates. Natural products like esculetin, fraxetin, daphnetin and other related coumarin derivatives are recognised as inhibitors not only of the lipoxygenase and cycloxygenase enzymic systems, but also of the neutrophil-dependent superoxide anion generation. Due to the unquestionable importance of coumarin derivatives considerable efforts have been made by several investigators, to prepare new compounds bearing single substituents, or more complicated systems, including heterocyclic rings mainly at 3-, 4- and / or 7-positions. In this review we shall deal with naturally occurring or synthetically derived coumarin derivatives, which possess antiinflammatory as well as antioxidant activities.

Oxygen, Reactive Oxygen Species and Tissue Damage

Abstract: The diatomic molecule of oxygen contains two uncoupled electrons and can therefore undergo reduction, yielding several different oxygen metabolites, which are collectively called Reactive Oxygen Species or ROS. They are invariably produced in aerobic environments through a variety of mechanisms, which include electron “leakage” during biologic oxidations, action of flavin dehydrogenases and specific membrane associated secretion, as well as by physical activation of oxygen by irradiation, e.g. UV sun-light. Organisms have developed efficient protective mechanisms against excessive accumulation of ROS, which include superoxide anion, hydrogen peroxide and hydroxyl radical, since all these metabolites are highly reactive and affect almost every kind of organism, either directly or through conversion into other derivatives, notably NO-derived radicals or RNS. Depending on their tissue concentration they can either exert beneficial physiologic effects (control of gene expression and mitogenesis) or damage cell structures, including lipids and membranes, proteins and nucleic acids, leading to cell death. In this brief overview we summarize the present state-of-theart, restricting the discussion to the role of ROS in physiology and pathology, not taking into account RNS. Discussion will focus on basic chemical and biochemical features of ROS, underlining how ROS can promote severe diseases, including neoplastic, cardiovascular and neurodegenerative diseases. This brief discussion should clarify the present huge interest in ROS, in the perspective to develop new and specific therapeutic approaches.

Studies on Coumarins and Coumarin-Related Compounds to Determine their Therapeutic Role in the Treatment of Cancer

Abstract: The Benzopyrones are a group of compounds whose members include coumarins and flavonoids. Dietary exposure to benzopyrones is quite significant, as these compounds are found in vegetables, fruit, seeds, nuts, coffee, tea and wine. It is estimated that the average western diet contains approximately 1 g/day of mixed benzopyrones. It is, therefore, not difficult to see why extensive research into their pharmacological and therapeutic properties is underway over many years. Coumarin is a natural substance that has shown anti-tumour activity in vivo, with the effect believed to be due to its metabolites (e.g. 7-hydroxycoumarin). This review is based on recent studies of coumarins and coumarin related compounds. Therefore, the focus will be on these relevant compounds and their therapeutic importance. A recent study has shown that 7-hydroxycoumarin inhibits the release of Cyclin D1, which is overexpressed in many types of cancer. This knowledge may lead to its use in cancer therapy. Esculetin inhibits growth and cell cycle progression by inducing arrest of the G(1) phase in HL-60 leukaemia cells, resulting from the inhibition of retinoblastoma protein phosphorylation. Recent studies investigating the potential of flavonoids as therapeutic agents have suggested they may have use in various therapeutic settings ranging from leukaemia treatment to the treatment of patients with HIV. Genistein is a well-known isoflavone and is a tyrosine kinase inhibitor. Studies have indicated that genistein elicits inhibitory effects on cell growth of various carcinoma cell-lines and may be a potential candidate for cancer therapy. In our research, we have investigated the effects of coumarins and coumarin-related compounds on a panel of cell-lines. The most recent work involves two cell-lines, MCF-7 a breast carcinoma and A549 a lung carcinoma. Microtitre assays were performed along with real-time analysis of cell viability using a biosensor called the Cytosensor microphysiometer. These studies suggest that both genistein and esculetin exerted the most potent inhibitory effect on cell growth in comparison to the other two compounds.

ABC Transporters and the Blood-Brain Barrier

Abstract: The blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) form a very effective barrier to the free diffusion of many polar solutes into the brain. Many metabolites that are polar have their brain entry facilitated by specific inwardly-directed transport mechanisms. In general the more lipid soluble a molecule or drug is, the more readily it will tend to partition into brain tissue. However, a very significant number of lipid soluble molecules, among them many useful therapeutic drugs have lower brain permeability than would be predicted from a determination of their lipid solubility. These molecules are substrates for the ABC efflux transporters which are present in the BBB and BCSB and the activity of these transporters very efficiently removes the drug from the CNS, thus limiting brain uptake. P-glycoprotein (Pgp) was the first of these ABC transporters to be described, followed by the multidrug resistance-associated proteins (MRP) and more recently breast cancer resistance protein (BCRP). All are expressed in the BBB and BCSFB and combine to reduce the brain penetration of many drugs. This phenomenon of "multidrug resistance" is a major hurdle when it comes to the delivery of therapeutics to the brain, not to mention the problem of cancer chemotherapy in general. Therefore, the development of strategies for bypassing the influence of these ABC transporters and for the design of effective drugs that are not substrates and the development of inhibitors for the ABC transporters becomes a high imperative for the pharmaceutical industry.

The Antioxidants and Pro-Antioxidants Network: An Overview

Abstract: Living beings have evolved over the past two billon years through adaptation, to an increasing atmospheric oxygen concentration, by both taking advantage of oxygen activating function and developing a complex control network. In these regards, potentially damaging species (reactive oxygen, nitrogen and chlorine species) arise as by-products of metabolism and also work as physiological mediators and signalling molecules. Oxidative stress may be an important factor in numerous pathological conditions, i.e. infection if micronutrient s are deficient. Levels of these species are controlled by the antioxidant defence system, which is composed by antioxidants and pro-antioxidants. Several components of this system are micronutrients (e.g. vitamins C and E), are dependent upon dietary micronutrients (e.g. CuZn and Mn superoxide dismutase) or are produced by specific endogenous pathways. The antioxidant defences act, to control levels of these species, as a coordinated system where deficiencies in one component may affect the efficiency of the others. In this network some of the components act as direct antioxidants whereas others act indirectly (pro- antioxidants) either by modulation of direct agents or by regulation of the biosynthesis of antioxidant proteins. Thus, entities usually not considered as antioxidants, also act efficiently counteracting damaging effects of oxidative species. In this contest, the design of new molecules that take into account synergistic interactions among different antioxidants, could be useful both to address mechanistic studies and to develop possible therapeutic agents. In this review the principal categories of antioxidants and pro-antioxidants that goes from vitamins through phyto-derivatives to minerals, are critically reviewed, with particular emphasis on structure-function considerations, together with the perspective opened, in the design of possible therapeutic agents, by the antioxidants interplay.

Propofol: therapeutic indications and side-effects.

Abstract: Propofol (2, 6-diisopropylphenol) is a potent intravenous hypnotic agent which is widely used for the induction and maintenance of anesthesia and for sedation in the intensive care unit. Propofol is an oil at room temperature and insoluble in aqueous solution. Present formulations consists of 1% or 2% (w/v) propofol, 10% soybean oil, 2.25% glycerol, and 1.2% egg phosphatide. Disodium edetate (EDTA) or metabisulfite is added to retard bacterial and fungal growth. Propofol is a global central nervous system depressant. It directly activates GABA(A) receptors. In addition, propofol inhibits the NMDA receptor and modulates calcium influx through slow calcium ion channels. Propofol has a rapid onset of action with a dose-related hypnotic effect. Recovery is rapid even after prolonged use. Propofol decreases cerebral oxygen consumption, reduces intracranial pressure and has potent anti-convulsant properties. It is a potent antioxidant, has anti-inflammatory properties and is a bronchodilator. As a consequence of these properties propofol is being increasingly used in the management of traumatic head injury, status epilepticus, delirium tremens, status asthmaticus and in critically ill septic patients. Propofol has a remarkable safety profile. Dose dependent hypotension is the commonest complication; particularly in volume depleted patients. Hypertriglyceridemia and pancreatitis are uncommon complications. Allergic complications, which may include bronchospasm, have been reported with the formulation containing metabisulfite. In addition, this formulation has been demonstrated to result in the generation of oxygen free radicals. High dose propofol infusions have been associated with the "propofol syndrome"; this is a potentially fatal complication characterized by severe metabolic acidosis and circulatory collapse. This is a rare complication first reported in pediatric patients and believed to be due to decreased transmembrane electrical potential and alteration of electron transport across the inner mitochondrial membrane.

The urokinase plasminogen activator system: role in malignancy.

Abstract: The urokinase plasminogen activator (uPA) system consists of the serine protease uPA, its glycolipid-anchored receptor, uPAR and its 2 serpin inhibitors, plasminogen activator inhibitor-1 (PAI-1) and plasminogen activator inhibitor-2 (PAI-2). Recent findings suggest that the uPA system is causally involved at multiple steps in cancer progression. In particular, uPA has been implicated in remodelling of the extracellular matrix, enhancing both cell proliferation and migration and modulating cell adhesion. Consistent with its role in cancer progression, multiple groups have shown that high levels of uPA in primary breast cancers are independently associated with adverse outcome. Paradoxically, high levels of PAI-1 also correlate with poor prognosis in patients with breast cancer. The prognostic value of uPA/PAI-1 in axillary node-negative breast cancer patients was recently validated using both a prospective randomised trial and a pooled analysis, i.e., in 2 different Level 1 Evidence studies. Assay of uPA and PAI-1 may thus help identify low risk node-negative patients for whom adjuvant chemotherapy is unnecessary. Finally, preclinical studies show that either inhibition of uPA catalytic activity or prevention of uPA binding to its receptor reduces tumor growth, angiogenesis and metastasis.

Cardiovascular Side Effects of New Antidepressants and Antipsychotics: New Drugs, old Concerns?

Abstract: The cardiovascular toxicity of older generation of tricyclic antidepressants (e.g. imipramine, desipramine, amitriptyline, clomipramine) and neuroleptics (e.g. haloperidol, droperidol, thioridazine, pimozide) is well established. These drugs inhibit cardiovascular Na(+), Ca(2+) and K(+) channels often leading to life-threatening arrhythmia. To overcome the toxicity of old generation of antidepressants and antipsychotics, selective serotonin reuptake inhibitor antidepressants (SSRIs: fluoxetine, fluvoxamine, paroxetine, sertraline, citalopram, venlafaxin) and several new antipsychotics (e.g. clozapine, olanzapine, risperidone, sertindole, aripiprazole, ziprasidone, quetiapine) were introduced during the past decade. Although these new compounds are not more effective in treating psychiatric disorders than older medications, they gained incredible popularity since they have been reported to have fewer and more benign side effect profile (including cardiovascular) than predecessors. Surprisingly, an increasing number of case reports have demonstrated that the use of SSRIs and new antipsychotics (e.g. clozapine, olanzapine, risperidone, sertindole, aripiprazole, ziprasidone, quetiapine) is associated with cases of arrhythmias, prolonged QTc interval on electrocardiogram (ECG) and orthostatic hypotension in patients lacking cardiovascular disorders, raising new concerns about the putative cardiovascular safety of these compounds. In agreement with these clinical reports these new compounds indeed show marked cardiovascular depressant effects in different mammalian and human cardiovascular preparations by inhibiting cardiac and vascular Na(+), Ca(2+) and K(+) channels. Taken together, these results suggest that the new generation of antidepressants and antipsychotics also have clinically important cardiac as well as vascular effects. Clinicians should be more vigilant about these potential adverse reactions and ECG control may be suggested during therapy, especially in patients with cardiovascular disorders. The primary goal of this review is to shed light on the recently observed clinically important cardiovascular effects of new antidepressants and antipsychotics and discuss the mechanism beyond this phenomenon.

Induction of cytoprotective genes through Nrf2/antioxidant response element pathway: a new therapeutic approach for the treatment of inflammatory diseases.

Abstract: In the last decade, it has become recognized that reactive oxygen species (ROS) play important roles in the multiple biological processes involved in the pathophysiology of chronic inflammation such as cell proliferation, adhesion molecule expression, cytokine and chemoattractant production and matrix metalloproteinase generation. Intracellular redox homeostasis is maintained by balancing the production of ROS with their removal through cellular antioxidant defense systems. The antioxidant response element (ARE) is a cis-acting DNA regulatory element located in the regulatory regions of multiple genes including phase II detoxification enzymes as well as antioxidant proteins including glutathione-S-transferases, NAD(P)H:quinone oxidoreductase-1, gamma-glutamylcysteine synthase, ferritin, and heme oxygenase-1. Nrf2 is the primary transcription factor that binds to the ARE, and through heterodimerization with other leucine-zipper containing transcription factors, activates the expression of these genes. It is evident that activation of ARE-regulated genes contributes to the regulation of cellular antioxidant defense systems. More importantly, there is a growing body of evidence suggesting that modulation of these cytoprotective genes has profound effects on immune and inflammatory responses. Activation of cytoprotective Nrf2/ARE-regulated genes can suppress inflammatory responses, whereas decreased expression of these genes results in autoimmune disease and enhanced inflammatory responses to oxidant insults. Thus, coordinate induction of cytoprotective genes through Nrf2/ARE pathway may represent a novel therapeutic approach for the treatment of immune and inflammatory diseases.

Cyclooxygenase enzymes: regulation and function.

Abstract: The cyclooxygenase isoenzymes, COX-1 and COX-2, catalyze the formation of prostaglandins, thromboxane, and levuloglandins. The prostaglandins are autocoid mediators that affect virtually all known physiological and pathological processes via their reversible interaction with G-protein coupled membrane receptors. The levuloglandins are a newer class of products that appear to act via irreversible, covalent attachment to numerous proteins. COX enzymes are clinically important because they are inhibited by aspirin and numerous other non-steroidal anti-inflammatory drugs. This inhibition of COX confers relief from inflammatory, pyretic, thrombotic, neurodegenerative and oncological maladies. About one hundred years have elapsed since Hoffman designed and synthesized acetylsalicylic (aspirin) as an agent intended to lessen the gastrointestinal irritation of salicylates while maintaining their efficacy. During the past forty years systematic advances in our understanding of the structure, regulation and function of COX isoenzymes have enabled the design and synthesis of COX-2 selective inhibitors as agents intended to lessen the gastrointestinal irritation of aspirin and non-selective NSAIDs. This review discusses: 1) how two separate catalytic processes in COX - peroxidase and prostaglandin synthase - act in an integrated fashion manner to generate prostaglandins; 2) why irreversible inactivation of COX is important constitutively and pharmacologically; 3) how cells have managed to use two closely related, almost identical enzymes in ways that discriminate their physiological versus pathological roles; 4) how investigators have used these advances to formulate and test medically important uses for old drugs (i.e. aspirin) and create new ones that still seek to achieve Hoffman's original goal.

The design and development of pegfilgrastim (PEG-rmetHuG-CSF, Neulasta)

Abstract: Recombinant protein technology produces drugs for human therapy in unprecedented quantity and quality. Research is now focusing on the relationship between pharmacokinetic and pharmacodynamic properties of molecules, with the aim of engineering proteins that possess enhanced therapeutic characteristics in contrast to being used as simple replacements for the natural equivalent. The addition of a polyethylene glycol (PEG) moiety to filgrastim (rmetHu-G-CSF, Neupogen) resulted in the development of pegfilgrastim. Pegfilgrastim is a long-acting form of filgrastim that requires only once-per-cycle administration for the management of chemotherapy-induced neutropenia. The covalent attachment of PEG to the N-terminal amine group of the parent molecule was attained using site-directed reductive alkylation. Pegylation increases the size of filgrastim so that it becomes too large for renal clearance. Consequently, neutrophil-mediated clearance predominates in elimination of the drug. This extends the median serum half-life of pegfilgrastim to 42 hours, compared with between 3.5 and 3.8 hours for Filgrastim, though in fact the half-life is variable, depending on the absolute neutrophil count, which in turn reflects of the ability of pegfilgrastim to sustain production of those same cells. The clearance of the molecule is thus dominated by a self-regulating mechanism. Pegfilgrastim retains the same biological activity as filgrastim, and binds to the same G-CSF receptor, stimulating the proliferation, differentiation and activation of neutrophils. Once-per-chemotherapy cycle administration of pegfilgrastim reduces the duration of severe neutropenia as effectively as daily treatment with filgrastim. In clinical trials, patients receiving pegfilgrastim also had a lower observed incidence of febrile neutropenia than patients receiving filgrastim.

Membrane disrupting lytic peptides for cancer treatments.

Abstract: Membrane disrupting lytic peptides are abundant in nature and serve insects, invertebrates, vertebrates and humans as defense molecules. Initially, these peptides attracted attention as antimicrobial agents; later, the sensitivity of tumor cells to lytic peptides was discovered. In the last decade intensive research has been conducted to determine how lytic peptides lyse bacteria and tumor cells. A number of synthetic peptides have been designed to optimize their antibiotic and anti-tumor properties and improve their therapeutic capabilities. The sequences of alpha-helical cationic membrane disrupting peptides has been discussed, their proposed mechanisms of action reviewed, and their roles in cell selectivity and tumor cell destruction considered. Parameters important for the selection and design of lytic peptides for cancer treatments include increased activities against tumor cells, low cytolytic activities to normal mammalian cells and erythrocytes. The conjugation of lytic peptides with hormone ligands and the production of pro-peptides provide methods for targeting of cancer cells. The therapeutic possibilities in cancer treatment by targeted lytic peptides are broad and offer improvement to currently used chemotherapeutical drugs. Lytic peptides interact with the tumor cell membrane within minutes, and their activity is independent of multi-drug resistance. Lytic peptide-chorionic gonadotropin (CG) conjugates destroy primary tumors, prevent metastases and kill dormant and metastatic tumor cells. These conjugates do not destroy vital organs; they are not antigenic, and are more toxic to tumor cells than to non-malignant cells.

Imaging β-Amyloid Plaques and Neurofibrillary Tangles in the Aging Human Brain

Abstract: The development of radioligands to image beta-amyloid (A beta) plaques and neurofibrillary tangles (NFTs) in vivo in the aging human brain is an important and active area of radiopharmaceutical design. When used in combination with positron emission tomography (Pet) or single photon emission computed tomography (spect), amyloid-imaging tracers could facilitate the evaluation of the efficacy of anti-amyloid therapies currently under intense development by many major pharmaceutical companies throughout the world. Amyloid-imaging agents could also serve as surrogate markers in early diagnosis and neuropathogenesis studies of Alzheimer's disease and other aging-related neurodegenerative disorders. In this review article, the design and biological evaluation of amyloid-imaging agents are discussed. The structures of these agents vary from large proteins and peptides such as radiolabeled A beta peptides and monoclonal antibodies to small molecules derived from Congo red, Chrysamine-G, thioflavin-T, and Acridine Orange. In vitro studies indicate that amyloid plaques contain multiple binding sites that can accommodate structurally diverse compounds, providing flexibility for radiopharmaceutical design of amyloid imaging agents. Compared to large biomolecules, small molecule radiotracers are often readily accessible through chemical synthesis and can display superior brain permeability. Several small molecule amyloid-imaging radioligands display high binding affinities to A beta and sufficient brain penetration for imaging studies. Recent studies demonstrate the feasibility of imaging amyloid plaques in vivo in human subjects with PET. Imaging NFTs, separately or in concert with A beta plaques, is not as far advanced as imaging A beta plaques and remains to be fully characterized and demonstrated.

Negative glucocorticoid receptor response elements and their role in glucocorticoid action.

Abstract: The glucocorticoid receptor (GR) belongs to the steroid hormone receptor subclass of nuclear receptors and controls physiological processes through activation and repression of specific target genes. The ligand-activated receptor dimer activates gene expression by binding to specific DNA sequences (glucocorticoid response element, GRE) in the promoter regions of glucocorticoid-regulated genes. In contrast to the regulation of these classical GREs, the repression of negatively regulated target genes is mediated by negative GREs (nGRE), composite GREs or by transrepression. Due to their broad therapeutic spectrum and superior therapeutic effects glucocorticoids (GCs) are the most effective drugs used for the treatment of acute and chronic inflammatory diseases. Unfortunately, long term systemic therapy with GCs is restricted due to their metabolic side effects. It is assumed that transrepression of transcription factors such as AP-1 and NF-kappa B is the main mechanism by which glucocorticoids mediate their anti-inflammatory activity, whereas the side effects of GCs are mainly mediated by GR-DNA-interaction either by activation or by negative regulation of gene expression. While trans-repression has been characterized in detail, the molecular mechanisms of DNA-dependent cis-repression remain unclear. In this review, we focus on current knowledge about nGRE-mediated target gene repression and the relevance and function of these genes for glucocorticoid action. Negative GREs contribute to the regulation of the hypothalamic-pituitary-adrenal (HPA) axis (POMC and CRH), bone (osteocalcin) and skin (keratins) function, inflammation (IL-1beta), angiogenesis (proliferin) and lactation (prolactin). The discovery of the underlying mechanisms, especially the comparison to positive GREs and trans-repression may help in the future to discover and analyze novel selective GR agonists.

Radiolabeled tracers for imaging of tumor angiogenesis and evaluation of anti-angiogenic therapies.

Abstract: A variety of therapeutic strategies in oncology are focused on the inhibition of tumor-induced angiogenesis. Thus, there is a keen interest in methods which allow non-invasive monitoring of molecular targets involved in angiogenesis which would support information for planning and controlling corresponding therapies. Moreover, such techniques would provide an insight into the formation of new sprouting blood vessels, the involved processes and regulatory mechanisms in patients. At the moment, development of radiotracer based techniques is mainly concentrated on three different targets which include peptidic and non-peptidic alpha v beta 3-integrin binding antagonists, matrix metalloproteinase inhibitors and single chain anti-fibronectin antibody fragments. Development of radiolabeled MMP inhibitors is based on either the decapeptide Cys-Thr-Thr-His-Trp-Gly-Phe-Thr-Leu-Cys resulting from a phage display library or small molecular weight compounds. The in vitro data for these tracers are very promising. However, more detailed in vivo data are necessary to evaluate the potency of MMP-inhibitors for in-vivo imaging. The radiolabelled anti-ED-B single chain antibody fragment scFv L-19 shows selective accumulation in the tumor vasculature in a murine tumour model. In a first patient study a selective localisation of the (123)I-labeled tracer in lesions of different tumours was found. On the basis of the lead structure cyclo(-Arg-Gly-Asp-dPhe-Val) a variety of different radiolabeled RGD-peptides has been developed for the non-invasive determination of the alpha v beta 3 expression. These developments include peptides labeled with minimum structural alteration, peptide carbohydrate conjugates, peptidomimetics based on the RGD-structure as well as heterodimeric, homodimeric and homotetrameric ligand systems. Many of the tracers show high alpha v beta 3-affinity and selectivity in vitro and receptor selective tumour accumulation with high image contrast in different murine tumour models. Further studies have to demonstrate that this approach can be translated to clinical settings allowing visualisation of alpha v beta 3-positive tumours and alpha v beta 3 expression during tumour-induced angiogenesis in patients.

Oxidative Stress During Myocardial Ischaemia and Heart Failure

Abstract: Oxidative stress is a condition in which oxidant metabolites exert their toxic effect because of an increased production or an altered cellular mechanism of protection. The heart needs oxygen avidly and, although it has powerful defence mechanisms, it is susceptible to oxidative stress, which occurs, for instance, during post-ischaemic reperfusion. Ischaemia causes alterations in the defence mechanisms against oxygen free radicals, mainly a reduction in the activity of mitochondrial superoxide dismutase and a depauperation of tissue content of reduced glutathione. At the same time, production of oxygen free radicals increases in the mitochondria and leukocytes and toxic oxygen metabolite production is exacerbated by re-admission of oxygen during reperfusion. Oxidative stress, in turn, causes oxidation of thiol groups and lipid peroxidation leading first to reversible damage, and eventually to necrosis. In man, there is evidence of oxidative stress (determined by release of oxidised glutathione in the coronary sinus) during surgical reperfusion of the whole heart, or after thrombolysis, and it is related to transient left ventricular dysfunction or stunning. Data on oxidative stress in the failing heart are scant. It is not clear whether the defence mechanisms of the myocyte are altered or whether the production of oxygen free radicals is increased, or both. Recent data have shown a close link between oxidative stress and apoptosis. Relevant to heart failure is the finding that tumour necrosis factor, which is found increased in failing patients, induces a rapid rise in intracellular reactive oxygen intermediates and apoptosis. This series of events is not confined to the myocytes, but occurs also at the level of endothelium, where tumour necrosis factor causes expression of inducible nitric oxide synthase, production of the reactive radical nitric oxide, oxidative stress and apoptosis. It is therefore, possible that the immunological response to heart failure results in endothelial and myocyte dysfunction through oxidative stress mediated apoptosis. Clarification of these mechanisms may lead to novel therapeutic strategies.

Pituitary adenylate cyclase activating polypeptide: a potential neuroprotective peptide.

Abstract: Pituitary adenylate cyclase activating polypeptide (PACAP) was first isolated from hypothalamic extracts on the basis of its ability to stimulate cAMP formation in pituitary cells. PACAP is widely distributed in the central and peripheral nervous systems and exerts numerous effects. Currently available data indicate that PACAP is a promising neuroprotective peptide. PACAP plays an important role during the development of the nervous system and in regeneration following nervous injuries. It has strong anti-apoptotic effects in several neuronal cultures and in vivo. PACAP protects neurons against various toxic insults in vitro, has anti-inflammatory actions and stimulates the release of neuroprotective substances from astrocytes. In vivo, the protective effects of PACAP have been shown in various models of brain injuries, including cerebral ischemia, Parkinson's disease, trauma and nerve transections. The upregulation of PACAP following several types of nerve injuries indicates that endogenous PACAP plays a role in the post-traumatic recovery of the nervous system. The present report reviews the current knowledge on the neurotrophic and neuroprotective effects of PACAP.

Use of sulfated fucans as anticoagulant and antithrombotic agents: future perspectives.

Abstract: Sulfated alpha-L-fucans from brown algae (also known as fucoidan) have complex and heterogeneous structures but recent studies revealed the occurrence of ordered repeat units in the sulfated fucans from several species. Even in these cases, the presence of highly branched portions and the complex distributions of sulfate and acetyl groups highlight the heterogeneity of algal fucans. Another source of sulfated alpha-L-fucans (and their parental compounds sulfated alpha-L-galactans and fucosylated chondroitin sulfate) is marine invertebrates. The invertebrate polysaccharides have simple, ordered structures, which differ in the specific patterns of sulfation and/or position of the glycosidic linkages within their repeating units. The algal and invertebrate sulfated fucans have potent anticoagulant activity, mediated by antithrombin and/or heparin cofactor II. As most of the studies were carried out with algal fucans it was not easy to trace a structure versus activity relationship. This aspect was clarified as studies were extended to invertebrate polysaccharides. These definitively established that regular, linear sulfated alpha-L-fucans and sulfated alpha-L-galactans express anticoagulant activity, which is not simply a function of charge density, but depends critically on the pattern of sulfation and monosaccharide composition. Sulfated alpha-L-fucans and fucosylated chondroitin sulfate also express antithrombotic activity when tested on in vivo models of venous and arterial thrombosis in experimental animals. These polysaccharides constitute potential therapeutic compounds as alternative to heparin and may help to design structure-based drugs with specific activity on each type of thrombosis episode and few side effects. They can also serve as research reagents to investigate and distinguish among a variety of interrelated events, such as coagulation, bleeding, thrombosis and platelet aggregation.

Targeted liposomal drug delivery in cancer.

Abstract: Liposomes, which are biodegradable and essentially non-toxic vehicles, can encapsulate both hydrophilic and hydrophobic materials, and are utilized as drug carriers in drug delivery systems. In addition, liposomes can be used to carry radioactive compounds as radiotracers can be linked to multiple locations in liposomes. One option is the hydrated compartment inside the liposome, another the lipid core into which especially hydrophobic conjugates can be attached, and the third option is the outer lipid leaflet where molecules can be bound by covalent linkage. Delivery of agents to the reticuloendothelial system (RES) is easily achieved, since most conventional liposomes are trapped by the RES. For the purpose of delivery of agents to target organs other than RES, long-circulating liposomes have been developed by modifying the liposomal surface. Understanding of the in vivo dynamics of liposome-carried agents is required for the evaluation of the bioavailability of drugs encapsulated in liposomes. In this review, we focus on the in vivo trafficking of liposomes visualized by positron emission tomography (PET) and discuss the characteristics of liposomes that affect the targeting of drugs in vivo.

A Review of Depsipeptide and Other Histone Deacetylase Inhibitors in Clinical Trials

Abstract: The histone deacetylase inhibitors (HDIs) are a new class of antineoplastic agents currently being evaluated in clinical trials. While these agents have been studied extensively in the laboratory, only recently has their mechanism of action begun to be elucidated. Several structural classes of compounds have been shown to exert histone deacetylase inhibition, including sodium n-butyrate, suberoylanilide hydroxamic acid, LAQ824, CI-994, MS-275, and depsipeptide. The HDIs have been shown to induce differentiation, to decrease cell proliferation, and to induce cell death. HDIs are thought to exert their anti-neoplastic effects by altering the expression of genes that play a role in the control of cell growth, and transformation. The HDIs have specific and well-defined effects on cancer cells. Preliminary results from clinical trials suggest that these agents are very promising. While there were sporadic case reports of activity using the early generation HDIs, dramatic responses have recently been observed in patients with T-cell lymphomas treated with depsipeptide, one of the newer agents. With the well-defined molecular effects on cancer cells, surrogate markers can be analyzed for evidence of activity and efficacy using either tumor samples or normal tissue. Presented in this review are details from clinical trials with both earlier and newer generations of HDIs. Toxicities specific to this class of agents are outlined and possibilities for rational combination therapies are discussed.

Discovery and development of GSK3 inhibitors for the treatment of type 2 diabetes.

Abstract: Originally identified as a modulator of glycogen metabolism, glycogen synthase kinase-3 (GSK3) is now understood to play an important regulatory role in a variety of pathways including initiation of protein synthesis, cell proliferation, cell differentiation, apoptosis, and is essential for embryonic development as a component of the Wnt signaling cascade. GSK3 can be considered as a target for both metabolic and neurological disorders. GSK3's association with neuronal apoptosis and hyper-phosphorylation of tau make this kinase an attractive therapeutic target for neurodegenerative conditions such as head trauma, stroke and Alzheimer's disease. While noting GSK3's many associated functions, this review will focus on GSK3 as a central negative regulator in the insulin signaling pathway, its role in insulin resistance, and the utility of GSK3 inhibitors for intervention and control of metabolic diseases including type 2 diabetes. Recent crystal structures, including the active (phosphorylated Tyr-216) form of GSK3beta, provide a wealth of structural information and greater understanding of GSK3's unique regulation and substrate specificity. Many potent and selective small molecule inhibitors of GSK3 have now been identified, and used in vitro to modulate glycogen metabolism and gene transcription, increase glycogen synthase activity and enhance insulin-stimulated glucose transport. The pharmacology of potent and selective GSK3 inhibitors (CT 99021 and CT 20026) is described in a number of in vitro and in vivo models following acute or chronic exposure. The efficacy of clinical candidates in diabetic primates and the implications for clinical development are discussed. The profile of activity is consistent with a unique form of insulin sensitization which is well suited for indications such as metabolic syndrome X and type 2 diabetes.

Pharmaceutical Care: Past, Present and Future

Abstract: Since the concept of Pharmaceutical Care was introduced from United States about twenty years ago, this initiative has become a dominant form of practice for thousands of pharmacists around the world. Currently, pharmaceutical care is understood as the pharmacists' compromise to obtain the maximum benefit from the pharmacological treatments of the patients, being therefore responsible of monitoring their pharmacotherapy. As the profession has moved from a product orientation (dispensing medications) to a patient focus, clinical training requirements have expanded. This is a slow but ongoing process, which started from a philosophical point of view, in order to transform the concept of Pharmacy from commodity-based, mercantile operations into a clinical profession in the community pharmacies. Since its introduction, there has been an ample debate on the definition of pharmaceutical care due to differences in Pharmacy systems and in health care structure among the different countries. Moreover, several implementation barriers exist, which are attributable to problems in education, skills, resources and environment. Indeed, an awareness of the problem resulting from the use of medicines exists and numerous studies reflect that drug use control is necessary since there is an important relationship between morbidity / mortality and pharmacotherapy. Thus, it is possible to evaluate the benefits of pharmaceutical care on patients' health and ultimately on society. Many studies have been conducted, which show that the provision of pharmaceutical care has its value in common pathologies such as diabetes, hypertension, asthma, hyperlipidemia, chronic pain, rheumatic diseases or psychiatric disorders, as well as in polymedicated patients. A large amount of data is currently being published in biomedical journals, in an effort to establish the clinical, economic and humanistic viability of pharmaceutical care. Thus, the aim of this review is to study the evolution of this practice from its beginning until nowadays. Furthermore, we have analyzed a number of implementation programs performed in countries of Europe, the United States and Latin America, focusing on clinical, economical and humanistic outcomes, and also, on the current concept of drug therapy problems (DTP) considered as failures in drug therapy. We conclude that the positive outcomes obtained with different programs of pharmaceutical care are making a beneficial change in patients' health but still more research projects should be conducted to support this change.

Acetylcholinesterase inhibition in Alzheimer's Disease.

Abstract: Alzheimer's Disease (AD) is the most common cause for dementia in our ageing population, which leads to a slowly progressive, irretrievable ruination of mental function. The destructive, primarily degenerative condition is neuropathologically characterized by the formation of amyloid plaques, neurofibrillary tangles and loss of neurons and synapses as well. Research during the past twenty years revealed early in the disease course a degeneration of cholinergic nuclei localised in the basal forebrain. Impairment of this cholinergic system, which projects into large areas of the limbic system and the neocortex is followed by disturbance of attentional processes and cognitive decline. The link between the cholinergic dysfunction and cognitive impairment has focused large scientific efforts to understand the neurobiology of cognition and to develop therapeutic tools for the fight against Alzheimer's Disease. Acetylcholinesterase inhibitors are currently the best established treatment for this devastating disease. This review describes historical aspects and the vast range of use of cholinesterase inhibitors in traditional societies and industrial nations. Second, the rational basis will be outlined for their development as medication, the so-called cholinergic hypotheses of AD. Third, acetylcholinesterase inhibitors currently available for the treatment of AD will be reviewed. This includes donepezil, galanthamine and rivastigmine. Tacrine, the first acetylcholinesterase inhibitor who became available in 1993 as a treatment for AD, does not play an essential role anymore besides his historical value, because of its hepatotoxicity. Although acetylcholinesterase inhibitors are no cure, these drugs can delay the progress of mental deterioration, reduce neuropsychiatric symptoms and therefore represent a rational therapeutic approach to the treatment of Alzheimer's Disease.

Pathophysiology and treatment of obesity hypertension.

Abstract: Excess weight gain accounts for as much as 65-75% of the risk for essential hypertension and also greatly increases the risk for end stage renal disease (ESRD). Obesity raises blood pressure by increasing renal tubular reabsorption, impairing pressure natriuresis, and causing volume expansion due to activation of the sympathetic nervous system (SNS) and renin-angiotensin aldosterone system (RAAS), and by physical compression of the kidneys, especially when visceral obesity is present. The mechanisms of SNS activation in obesity are still unclear but may be due, in part, to hyperleptinemia that stimulates the hypothalamic pro-opiomelanocortin (POMC) pathway. With prolonged obesity, there may be a gradual loss of kidney function that worsens with time, exacerbates hypertension, and makes blood pressure more difficult to control. Lifestyle modifications, including weight reduction and increased physical activity, are essential first steps in the management of obesity hypertension and renal disease. Anti-obesity drugs offer potential pharmacotherapy for obesity hypertension, but current drugs are very limited and additional long-term studies are needed to test their safety and efficacy. Clinical trials are also needed to determine the most effective antihypertensive drugs for obese hypertensive patients. Special considerations for the obese patient, in addition to adequately controlling the blood pressure, include correcting the metabolic abnormalities and protecting the kidneys from further injury.

Recent Development and Application of Virtual Screening in Drug Discovery: An Overview

Abstract: Virtual screening, especially the structure-based virtual screening, has emerged as a reliable, cost-effective and time-saving technique for the discovery of lead compounds. Here, the basic ideas and computational tools for virtual screening have been briefly introduced, and emphasis is placed on aspects of recent development of docking-based virtual screening, scoring functions in molecular docking and ADME/Tox-based virtual screening in the past three years (2000 to 2003). Moreover, successful examples are provided to further demonstrate the effectiveness of virtual screening in drug discovery.

Can an apple a day keep the doctor away

Abstract: The modern pharmaceutical industry based on synthetic chemistry severed the historical connection between plants, food and medicines. The growing costs of discovering new chemical entity-based drugs through high throughput screening methods may yet again reconnect plants and human health at a new level of technological sophistication. Multi-component botanical therapeutics that comprise functional foods, dietary supplements and botanical drugs hold several advantages over conventional drugs that may earn them a more prominent place in the medicine of the future. They can deliver mixtures of multi-functional molecules with potentiating and synergistic effects and pleiotropic targeting at a reasonable cost and with fewer regulatory constraints. They are well suited for long-term disease prevention in an era of genetic testing and increased life expectancy. They also provide additional vehicles for delivering health and wellness. Technologies that address the needs of discovery, development and manufacturing of multi-component botanical therapeutics are emerging. They include computational and bioinformatics approaches, cell based gene expression and high-content screening systems, and phytochemical elicitation and unique plant cultivation / extraction methods designed to optimize the production of bioactives, standardize overall extract composition and assure batch-to-batch product consistency. Nevertheless, multi-component botanical therapeutics carry risks associated with potential interactions with conventional drugs and adverse reactions, which are difficult to detect and diagnose. They face problems of acceptance by the medical community and pharmaceutical industry, safety and efficacy validation, poor standardization and quality control, and difficulties in identifying active ingredients and determining their complex mode(s) of action. Solving these problems will accelerate the merger of grocery stores with pharmacies and agriculture with chemical manufacturing and provide physicians and patients with broader and more individualized choices for disease prevention and treatment.

Clinical development of microbicides for the prevention of HIV infection.

Abstract: The HIV/AIDS pandemic continues its spread at a rate of over 15,000 new infections every day. Sexual transmission of HIV-1 is the dominant mode of this pandemic spread. For the first time since the disease emerged in the early 1980s, about half the 42 million people now living with HIV/AIDS worldwide are women. Worldwide, more than 90 percent of all adolescent and adult HIV infections have resulted from heterosexual intercourse. The "feminization" of the pandemic largely driven by the social, economic, and biological factors warrants urgent attention particularly for the adolescent female population. In the absence of an effective prophylactic anti-HIV therapy or vaccine, current efforts are aimed at developing intravaginal/intrarectal topical formulations of anti-HIV agents or microbicides to curb the mucosal and perinatal HIV transmission. Microbicides would provide protection by directly inactivating HIV or preventing HIV from attaching, entering or replicating in susceptible target cells as well as dissemination from target cells present in semen or the host cells that line the vaginal/rectal wall. Thus, ideally, anti-HIV microbicides should be capable of attacking HIV from different angles. In addition, a contraceptive microbicide could help prevent unintended pregnancies worldwide. To be a microbicide, these agents must be safe, effective following vaginal or rectal administration, and should cause minimal or no genital symptoms following long-term repeated usage. A safe and efficacious anti-HIV microbicide is not yet available despite the fact that more than 60 candidate agents have been identified to have in vitro activity against HIV, 18 of which have advanced to clinical testing. Targeting HIV entry has been a favored approach because it is the first step in the process of infection and several readily available anionic polymeric products seem to variably interfere with these processes are the primary candidates for potential microbicides. Formulations of some anionic polymeric antiviral agents have been tested at various doses and various durations for safety, tolerability, and acceptability in Phase I/II clinical trials (vaginal, rectal, or penile studies) in HIV-uninfected and/or HIV-infected populations. Current multicenter Phase I/II safety and Phase II/III efficacy studies that are being conducted or planned in different geographical locations by various special interest groups are designed for rapid clinical development of candidate products. The currently marketed detergent-type spermicide, nonoxynol-9 (N-9), has failed in Phase III clinical trials, due to the drug-induced formation of localized genital lesions that might in fact actually promote virus transmission. Alternative "first-generation" microbicides that have undergone Phase I/II safety and tolerability studies in HIV-uninfected and/or HIV-infected volunteers include polymeric viral fusion inhibitors (dextrin sulfate/Emmelle, carrageenans [PC-213, PC-503, PC-515/Carraguard], cellulose sulfate/Ushercell, polystyrene sulfonate, naphthalene sulfonate [PIC 024-4/PRO 2000/5], acidifying gel [Carbomer 974P/BufferGel], Lactobacillus (L. crispatus) suppository/CTV-05, detergent-type dual-function barriers [ACIDFORM, GEDA Plus, SURETE, Glyminox/C31G/Savvy, Invisible Condom], herbal extracts [Praneem], and viral replication inhibitors [PMPA/Tenofovir]. For majority of these products, no information is available regarding their long-term mucosal safety, carcinogenicity potential, bioavailability, or efficacy following their extended vaginal or rectal exposure. The irritative genitourinary symptoms reported for a number of these first-generation products in Phase I clinical trials implies that the "soft" preclinical endpoints for mucosal safety established for the use and development of vaginal spermicides may not be rigorous enough for vaginal and rectal microbicides because of the efficient sexual tra virus diversity, and genetic environment. It is now apparent that sexually transmitted R5 HIV-1 viruses have less positive charge on their surface compared with the R4 HIV-1 viruses, which may limit the anionic polymers as topical microbicides despite extensive clinical trials. Nevertheless, their ongoing clinical trials, reviewed here, using optimized formulations, and special populations in various geographic locations are paving the way for future rigorous clinical testing of "mechanism-based" broad-spectrum anti-HIV microbicides that are currently under intense development. It is anticipated that future microbicide trials will focus on combination of products capable of attacking HIV life cycle at multiple steps intended to increase efficacy, limit cross-resistance as well as minimize microbicide-induced host toxicity.

The impact of pharmaceutical care practice on the practitioner and the patient in the ambulatory practice setting: twenty-five years of experience.

Abstract: This manuscript reviews 25 years of experience that include developing the practice of pharmaceutical care and initiating new practices. The impact this practice has on practitioners in the ambulatory setting is described as well as data that reflect its clinical and economic impact. There is a great need to prepare new practitioners to provide pharmaceutical care. A focused training program was developed and delivered to over 300 practitioners. The practitioners were prepared by providing direct patient care. They learned the philosophy of pharmaceutical care practice, to identify, resolve and prevent drug therapy problems, to document care using a specially designed software program called the Assurance Pharmaceutical Care program. The practitioners who participated in the training program reported that the average amount of time spent with patients increased three-fold, they now see four times more patients than prior to training, and the number of new patients referred by physicians increased nine-fold as a result of the program. These practitioners have now provided care to more than 25,000 patients in their practices. These data have now been consolidated and analyzed, and a portion of these results is reported here. The clinical and economic outcomes from 2,985 adult patients, who received pharmaceutical care between January, 2000 and December, 2003, are presented. At the first assessment by the pharmaceutical care practitioner, 61% of the patients had one or more drug therapy problems identified and resolved. This resulted in an improvement in the clinical status or maintaining a stable status in 83% of the patients. The health care savings realized from pharmaceutical care were $1,134,162. This represented a benefit to cost ratio of 2:1. Physicians who collaborate with pharmaceutical care practitioners have validated the work of the practitioners, and patients are recognizing the benefits of pharmaceutical care.

Microdialysis in neurointensive care.

Abstract: Microdialysis is a technique for sampling the chemistry of the interstitial fluid of tissues and organs in animal and man. It is minimally invasive and simple to perform in a clinical setting. Although microdialysis samples essentially all small molecular substances present in the interstitial fluid the use of microdialysis in neurointensive care has focused on markers of ischemia and cell damage. The lactate/pyruvate ratio is a well-known marker of changes in the redox state of cells caused by ischemia Glycerol is an integral component of cell membranes. Loss of energy due to ischemia eventually leads to an influx of calcium and a decomposition of cell membranes, which liberates glycerol into the interstitial fluid. Thus the lactate/pyruvate ratio and glycerol have become the most important markers of ischemia and cell membrane damage. While the primary insult at the site of the accident is beyond our control, secondary insults during intensive care should be avoided by all means. Therefore, the single most important finding from microdialysis studies is the dramatic difference in the vulnerability of the penumbra surrounding a lesion as compared to normal brain tissue allowing early detection of secondary insults after traumatic brain injury as well as the onset of vasospasm after subarachnoid hemorrhage.

The role of STATs in inflammation and inflammatory diseases.

Abstract: The immune response is regulated by the concerted action of pro- and anti-inflammatory cytokines. The deregulation of this process causes immunological disorders like allergic and autoimmune diseases. The Janus Kinase (JAK) - Signal transducer and activator of transcription (STAT) pathway is one major signaling pathway converting the cytokine signal into gene expression programs regulating the proliferation and differentiation of the immune cells. Several members of the STAT protein family in particular STAT1, STAT2, STAT3, STAT4 and STAT6 act as transcription factors in modulating pro- and anti-inflammatory responses. Here we review the evidence for the involvement of the different STAT proteins in inflammation, autoimmune and allergic diseases. We discuss novel approaches to interfere with the function of these signaling transcription factors for therapeutic purpose.