Rosiglitazone treatment restores renal responsiveness to atrial natriuretic peptide in rats with congestive heart failure.

The thiazolidinedione (TZD) class of Peroxisome proliferator-activated receptor gamma agonists has restricted clinical use for diabetes mellitus due to fluid retention and potential cardiovascular risks. These side effects are attributed in part to direct salt-retaining effect of TZDs at the renal collecting duct. A recent study from our group revealed that prolonged rosiglitazone (RGZ) treatment caused no Na+/H2 O retention or up-regulation of Na+ transport-linked channels/transporters in experimental congestive heart failure (CHF) induced by surgical aorto-caval fistula (ACF). The present study examines the effects of RGZ on renal and cardiac responses to atrial natriuretic peptide (ANP), Acetylcholine (Ach) and S-Nitroso-N-acetylpenicillamine (SNAP-NO donor). Furthermore, we assessed the impact of RGZ on gene expression related to the ANP signalling pathway in animals with ACF. Rats subjected to ACF (or sham) were treated with either RGZ (30 mg/kg/day) or vehicle for 4 weeks. Cardiac chambers pressures and volumes were assessed invasively via Miller catheter. Kidney excretory and renal hemodynamic in response to ANP, Ach and SNAP were examined. Renal clearance along with cyclic guanosine monophosphate (cGMP), gene expression of renal CHF-related genes and ANP signalling in the kidney were determined. RGZ-treated CHF rats exhibited significant improvement in the natriuretic responses to ANP infusion. This 'sensitization' to ANP was not associated with increases in neither urinary cGMP nor in vitro cGMP production. However, RGZ caused down-regulation of several genes in the renal cortex (Ace, Nos3 and Npr1) and up-regulation of ACE2, Agtrla, Mme and Cftr along down-regulation of Avpr2, Npr1,2, Nos3 and Pde3 in the medulla. In conclusion, CHF+RGZ rats exhibited significant enhancement in the natriuretic responses to ANP infusion, which are known to be blunted in CHF. This 'sensitization' to ANP is independent of cGMP signalling, yet may involve post-cGMP signalling target genes such as ACE2, CFTR and V2 receptor. The possibility that TZD treatment in uncomplicated CHF may be less detrimental than thought before deserves additional investigations.

Synergistic effect of liver X receptor activation and simvastatin on plaque regression and stabilization: an magnetic resonance imaging study in a model of advanced atherosclerosis.

AIMS: The aim of this study was to investigate the effects of liver X receptors (LXRs)-ß preferential activation by LXR-623 (WAY-252623), a novel LXRs agonist, on plaque progression/regression in a rabbit model of advanced atherosclerosis. METHODS AND RESULTS: Advanced atherosclerosis was induced in New Zealand White Rabbits (n= 41). At the end of atherosclerosis induction, animals underwent a baseline magnetic resonance imaging (MRI) and were randomized to receive LXR-623 (1.5, 5, or 15 mg/kg/day), simvastatin (5 mg/kg/day), or placebo. The combination of LXR-1.5/simvastatin was also tested. After a final MRI, animals were euthanized and their aortas processed for further analysis. Simvastatin significantly reduced lesion progression (-25%; P< 0.01) in comparison with the placebo group. A similar effect was observed in the LXR-1.5 and -5 groups. A significant regression (16.5%; P< 0.01) of existing atherosclerosis was observed in the LXR-1.5/simvastatin group. Histological and molecular analysis showed plaque stabilization in the animals treated with the LXR-1.5 and -5, and LXR-1.5/simvastatin. The effects of LXR-623 were observed in the presence of a non-significant effect on total-cholesterol, low-density lipoproteins-cholesterol, and triglyceride levels. CONCLUSION: The results of the present study show that LXR-623 significantly reduces the progression of atherosclerosis and induces plaque regression in combination with simvastatin. These observations could drive future development of novel anti-atherosclerotic therapeutic approaches.

Sputum matrix metalloproteinase-12 in patients with chronic obstructive pulmonary disease and asthma: relationship to disease severity.

BACKGROUND: Matrix metalloproteinase (MMP)-12 has been implicated in the pathogenesis of both chronic obstructive pulmonary disease (COPD) and asthma. The influence of disease severity on sputum MMP-12 concentrations and activity is not known. OBJECTIVES: We sought to examine the relationship between disease severity assessed by means of lung function and computed tomography (CT) and induced sputum MMP-12 concentrations and activity in patients with asthma and COPD. METHODS: In 208 subjects (109 asthmatic patients, smokers and never smokers, mild, moderate, and severe; 53 patients with COPD, smokers and exsmokers, mild, moderate, and severe; and 46 healthy control subjects, smokers and never smokers), we measured induced sputum MMP-12 concentrations (ELISA) and enzyme activity (fluorescence resonance energy transfer), sputum cell MMP12 mRNA expression (quantitative PCR [qPCR]), diffusing capacity for carbon monoxide (Dlco), and CT assessment of emphysema (percentage of low-attenuation areas at less -950 Hounsfield units). RESULTS: Sputum MMP-12 concentrations are greater in patients with COPD and smokers with asthma than in healthy nonsmokers (P = .003 and P = .035, respectively) but similar to those seen in healthy smokers. In patients with COPD, disease severity, when measured by means of CT-assessed emphysema, but not by means of spirometry or Dlco values, is directly associated with sputum MMP-12 concentrations and activity. In the asthma groups there is no significant association between disease severity and sputum MMP-12 concentrations or activity. CONCLUSIONS: Sputum MMP-12 concentrations and activity in patients with COPD are directly associated with the extent of emphysema measured by means of CT. This finding supports a role for MMP-12 in the pathogenesis of COPD and might suggest that blocking MMP-12 activity in patients with COPD could prevent the further development of emphysema.

Clinical validity of plasma and urinary desmosine as biomarkers for chronic obstructive pulmonary disease.

BACKGROUND: Although an increased concentration of degraded elastin products in patients with chronic obstructive pulmonary disease (COPD) has been reported for many years, its clinical validity and utility remain uncertain due to technical difficulties, small study groups and the unknown relationship between exacerbation and elastin degradation. The objectives of this study were to determine the validity of urinary and blood total desmosine/isodesmosine in patients with COPD and asthma and to evaluate their relationship to exacerbation status and lung function. METHODS: Urinary and blood desmosine levels were measured using validated isotopic dilution liquid chromatography-tandem mass spectrometry methods. RESULTS: 390 study participants were recruited from the following groups: healthy volunteers, stable asthma, stable and 'during an exacerbation' COPD. Compared with healthy non-smokers, we found increased urinary or blood desmosine levels in patients with COPD, but no differences in patients with asthma or healthy smokers. The elevation of urinary desmosine levels was associated with the exacerbation status in patients with COPD. Approximately 40% of patients with stable and 'during an exacerbation' COPD showed elevated blood desmosine levels. Blood desmosine levels were strongly associated with age and were negatively correlated with lung diffusing capacity for carbon monoxide. CONCLUSION: The results suggest that urinary desmosine levels are raised by exacerbations of COPD whereas blood desmosine levels are elevated in a subgroup of patients with stable COPD and reduced lung diffusing capacity. The authors speculate that a raised blood desmosine level may identify patients with increased elastin degradation suitable for targeted therapy. Future prospective studies are required to investigate this hypothesis.

Multimodal biomarker investigation on efficacy and mechanism of action for the mammalian target of rapamycin inhibitor, temsirolimus, in a preclinical mammary carcinoma OncoMouse model: a translational medicine study in support for early clinical development.

The mammalian target of rapamycin (mTOR) has proven to be a valid therapeutic target in a number of human cancers, and it is a candidate for clinical trials in human breast cancer. We report on a biomarker-based translational medicine approach to assess the efficacy and mechanism of action for the mTOR inhibitor temsirolimus (CCI-779) in a mammary carcinoma OncoMouse model [polyomavirus middle T antigen (PyMT)]. The mTOR signaling pathway biomarkers were assessed using a reverse-phase protein array. Pharmacokinetics studies were conducted in both the tumor and plasma compartments. Pharmacodynamic biomarkers for compound-target engagement of tumor phospho-S6 proteins were assayed by Western blot. Temsirolimus (intravenously once a week for 2 weeks) was administered in both early and advanced stages of tumors. Biomarkers for temsirolimus effects on tumor progression were assessed by three-dimensional ultrasound imaging in combination with immunohistochemistry to assess vascular density (Texas red-dextran and CD31 immunostaining) and macrophage burden (F4/80 antigen). Tumor growth was significantly arrested in temsirolimus (25 ± 14% from 8 to 10 weeks, p < 0.05, and 26 ± 17% from 11 to 13 weeks, p < 0.01), compared with 493 ± 160 and 376 ± 50% increases, respectively, in vehicle-treated groups. Temsirolimus reduced tumor vascular density, 36 to 48 and 58 to 60%, p < 0.05, by the Texas red-dextran method or CD31-positive vessel count, respectively. Temsirolimus reduced tumor macrophage burden by 46% at 13 weeks (p < 0.05). Temsirolimus inhibited (p < 0.05) the phosphoproteins S6 pS235/236 and S6 pS240/244 up to 81 and 87%, respectively. We conclude that the multimodal biomarkers of temsirolimus efficacy and mechanism of action (phosphoproteins) strongly suggest that it might translate to therapeutic efficacy in human tumors that bear congruency to features present in the mammary carcinoma of PyMT tumors.

A Strategy to Detect Emerging Non-Delta SARS-CoV-2 Variants with a Monoclonal Antibody Specific for the N501 Spike Residue.

Efforts to control SARS-CoV-2 have been challenged by the emergence of variant strains that have important implications for clinical and epidemiological decision making. Four variants of concern (VOCs) have been designated by the Centers for Disease Control and Prevention (CDC), namely, B.1.617.2 (delta), B.1.1.7 (alpha), B.1.351 (beta), and P.1 (gamma), although the last three have been downgraded to variants being monitored (VBMs). VOCs and VBMs have shown increased transmissibility and/or disease severity, resistance to convalescent SARS-CoV-2 immunity and antibody therapeutics, and the potential to evade diagnostic detection. Methods are needed for point-of-care (POC) testing to rapidly identify these variants, protect vulnerable populations, and improve surveillance. Antigen-detection rapid diagnostic tests (Ag-RDTs) are ideal for POC use, but Ag-RDTs that recognize specific variants have not yet been implemented. Here, we describe a mAb (2E8) that is specific for the SARS-CoV-2 spike protein N501 residue. The 2E8 mAb can distinguish the delta VOC from variants with the N501Y meta-signature, which is characterized by convergent mutations that contribute to increased virulence and evasion of host immunity. Among the N501Y-containing mutants formerly designated as VOCs (alpha, beta, and gamma), a previously described mAb, CB6, can distinguish beta from alpha and gamma. When used in a sandwich ELISA, these mAbs sort these important SARS-CoV-2 variants into three diagnostic categories, namely, (1) delta, (2) alpha or gamma, and (3) beta. As delta is currently the predominant variant globally, they will be useful for POC testing to identify N501Y meta-signature variants, protect individuals in high-risk settings, and help detect epidemiological shifts among SARS-CoV-2 variants.

Pharmacodynamic Studies of Fluorescent Diamond Carriers of Doxorubicin in Liver Cancer Cells and Colorectal Cancer Organoids.

BACKGROUND: We recently reported on preferential deposition of bare fluorescent diamond particles FDP-NV-700/800nm (FDP-NV) in the liver following intravenous administration to rats. The pharmacokinetics of FDP-NV in that species indicated short residency in the circulation by rapid clearance by the liver. Retention of FDP-NV in the liver was not associated with any pathology. These observations suggested that cancer therapeutics, such as doxorubicin, linked to FDP-NV, could potentially serve for anti-cancer treatment while sparing toxicities of peripheral organs. PURPOSE: To generate proof-of-concept (POC) and detail mechanisms of action of doxorubicin-coated FDP-NV-700/800nm (FDP-DOX) as a prospective chemotherapeutic for metastatic liver cancer. METHODS: FDP-DOX was generated by adsorption chemistry. Experimental design included concentration and time-dependent efficacy studies as compared with naïve (baren) FDP-NV in in vitro liver cancer cells models. Uptake of FDP-NV and FDP-DOX by HepG-2, Hep-3B and hCRC organoids were demonstrated by flow-cytometry and fluorescent microscopy. FDP-DOX pharmacodynamic effects included metabolic as well as cell death biomarkers Annexin V, TUNEL and LDH leakage. DOX desorpted from FDP-DOX was assessed by confocal microscopy and chemical assay of cells fractions. RESULTS: FDP-DOX efficacy was dose- and time-dependent and manifested in both liver cancer cell lines and human CRC organoids. FDP-DOX was rapidly internalized into cancer cells/organoids leading to cancer growth inhibition and apoptosis. FDP-DOX disrupted cell membrane integrity as evident by LDH release and suppressing mitochondrial metabolic pathways (AlamarBlue assay). Access of free DOX to the nuclei was confirmed by direct UV-Visible fluorescent assay and confocal microscopy of DOX fluorescence. CONCLUSION: The rapid uptake and profound cancer inhibition observed using FDP-DOX in clinically relevant cancer models, highlight FDP-DOX promise for cancer chemotherapeutics. We also conclude that the in vitro data justify further investment in in vivo POC studies.

Stoichiometric quantification of Akt phosphorylation using LC-MS/MS.

The Ptdlns-3-kinase (PI3-K) signaling pathway plays a vital role in cell survival, proliferation, apoptosis and differentiation in normal cells, as well as in diseases such as cancer and diabetes. Quantification of phospho-Akt is a standard way of assessing the activity of the PI3-K signaling pathway in both cells and tumors. This measurement is traditionally performed semiquantitatively using immunoassays such as Western blot. Here we report an LC-MS method to accurately measure the stoichiometry of Akt phosphorylation in biological samples. The procedure includes immunoprecipitation, gel electrophoresis, in-gel digestion, addition of isotopicaly labeled internal standards and LC-MS/MS. Two proteolytic enzymes, chymotrypsin and trypsin, were used to generate suitable peptide fragments for measuring Thr308 and Ser473 phosphorylation, respectively. The interday imprecision was estimated to be 3.8% and 2.3% for Thr308 and Ser473, respectively. This method has been tested on human T-cells grown in presence and absence of pervanadate and with or without a PI3-K inhibitor and on human glioblastoma cells (U-87 MG) grown in presence and absence of wortmannin (PI3-K inhibitor).The results of T cells suggest that the levels of Akt phosphorylation in untreated cells were below 1% for both phosphorylation sites. Pervanadate treatment provoked an 18-fold increase in phosphorylation of Thr308 and the PI3-K inhibitor partially reversed the increase. A comparison between LC-MS/MS and Western blotting suggests that the LC-MS based method is of comparable sensitivity and provides a more accurate phosphorylation stoichiometry, a wider dynamic range and more in-depth information. The application of the new method and its utility to providing predictive markers of response to targeted therapies is discussed.

Pharmacogenomic, physiological, and biochemical investigations on safety and efficacy biomarkers associated with the peroxisome proliferator-activated receptor-gamma activator rosiglitazone in rodents: a translational medicine investigation.

Peroxisome proliferator-activated receptor (PPAR)-gamma modulators, a class of antidiabetic drugs, have been associated with cardiovascular risks in type 2 diabetes in humans. The objective of this study was to explore possible cardiovascular risk biomarkers associated with PPAR-gamma in rodents that could provide an alert for risk to humans. Normal, myocardial infarction-induced heart failure (HF) or Zucker diabetic fatty (ZDF) rats were used. Rats (n = 5-6) were treated with either vehicle or rosiglitazone (RGZ; 3 or 45 mg/kg/day p.o.) for 4 weeks. Biomarkers for potential cardiovascular risks were assessed, including 1) ultrasound for cardiac structure and function; 2) neuroendocrine and hormonal plasma biomarkers of cardiovascular risk; 3) pharmacogenomic profiling of cardiac and renal tissue by targeted tissue low-density gene array representing ion channels and transporters, and components of the renin-angiotensin-aldosterone system; and 4) immunohistochemistry for cardiac fibrosis, hypertrophy, and inflammation (macrophages and tumor necrosis factor-alpha). HF was confirmed by increase in cardiac brain natriuretic peptide expression (p < 0.01) and echocardiography. Adequate exposure of RGZ was confirmed by pharmacokinetics (plasma drug levels) and the pharmacodynamic biomarker adiponectin. In normal or HF rats, RGZ had no negative effects on any of the biomarkers investigated. Similarly, RGZ had no significant effects on gene expression except for the increase in interleukin-6 mRNA expression in the heart and decrease in epithelial sodium channel beta in the kidney. In contrast, echocardiography showed improved cardiac structure and function after RGZ in ZDF rats. Taken together, this study suggests a limited predictive power of these preclinical models in respect to observed clinical adverse effects associated with RGZ.

Peroxisome proliferator-activated receptor alpha and alpha/gamma agonists do not cause impairment in renal function in the rat.

BACKGROUND/AIMS: Patients treated with peroxisome proliferator-activated receptor analogs (PPAR) alpha or alpha/gamma may develop a transient and reversible increase in serum creatinine, the mechanism of which remains obscure. This study evaluates whether treatment with either PPAR-alpha or -alpha/gamma analogs, fenofibrate or tesaglitazar, may cause deterioration in renal hemodynamics or exert direct tubular or glomerular nephrotoxic effects in rats. METHODS: Male Sprague-Dawley rats (300-320 g) were treated per os with fenofibrate (300 mg/kg/day), tesaglitazar (1.2 mg/kg/day) or vehicle, for 14 days. Glomerular filtration rate (GFR) and renal blood flow (RBF) were measured by inulin clearance and ultrasonic flowmetry, and cumulative excretion of sodium and creatinine were assessed. Biomarkers of glomerular and tubular injury were measured, including urinary albumin excretion and renal mRNA levels of kidney injury molecule 1 (Kim-1), lipocalin 2 (Lcn2), and osteopontin (Spp1). RESULTS: Fenofibrate and tesaglitazar improved the lipid profile, but caused no detectable decrease in GFR or RBF compared with vehicle-treated rats. Furthermore, the cumulative excretions of sodium and creatinine were not altered by the drugs. Finally, there was no significant difference between drug- and vehicle-treated groups in urinary albumin excretion or in the expression of renal injury biomarkers. CONCLUSIONS: In the rat, no direct nephrotoxic effect or deterioration in renal hemodynamics and function were observed following treatment with fenofibrate or tesaglitazar.

Correlation between 2- and 3-dimensional assessment of tumor volume and vascular density by ultrasonography in a transgenic mouse model of mammary carcinoma.

OBJECTIVE: Visualization and quantification of angiogenesis are instrumental in development of antiangiogenic therapy. Although both 2-dimensional (2D) and 3-dimensional (3D) ultrasonography have been used to monitor tumor growth and vasculature development, the correlation between them has not been sufficiently investigated. We hereby investigated the 2D and 3D sonographic correlation for tumor volume and vascular density confirmed by histologic assessment in the polyoma virus middle T antigen (PyMT) mouse model of mammary carcinoma. METHODS: Female PyMT mouse tumors were evaluated by ultrasonography in the 2D region of interest (ROI), 3D tumor volume, and 2D and 3D microvascular density after a bolus infusion of a nontargeted contrast-enhanced microbubble agent. Texas Red-dextran was used for quantitative histologic assessment of the tumor microvascular density. RESULTS: The individual 2D tumor ROI area correlated with the 3D tumor volume throughout the 2-week period. However, the extent of the increase in the 3D volume (380%; P < .01; n = 10) was higher than that of the 2D ROI area (72%; P < .01; n = 8-11). A significant and comparable increase in vascular density accessed by both 2D (87%; P < .05; n = 8) and 3D (64%; P < .05; n = 8) imaging was documented. Vascular density obtained through 3D imaging correlated significantly with 2D measurement. These data were confirmed by Texas Red-dextran quantification of vascular density. Conclusions. This study showed a valid application of sonographically based imaging technology in tumor volume and vascular density assessment as well as their 2D and 3D correlation, of which tumor vascular density measured by 2D ultrasonography appeared to be better correlated with the 3D data. Our data indicate that ultrasonography can be applied for real-time, accurate, noninvasive imaging of the tumor volume and vascular density in preclinical models.

Effects of Fluorescent Diamond Particles FDP-NV-800nm on Essential Biochemical Functions of Primary Human Umbilical Vein Cells and Human Hepatic Cell Line, HepG-2 in vitro (Part VI): Acute Biocompatibility Studies.

BACKGROUND: Recently, we reported the safety and biocompatibility of fluorescent diamond particles, FDP-NV-Z-800nm (FDP-NV) injected intravenously into rats, where no morbidity and mortality were noted over a period of 3 months. The acute effects of FDP-NV-800nm particles on cultured human endothelial and hepatic cells remain unexplored. PURPOSE: In this study, we aimed to explore select cellular and biochemical functions in cultured human umbilical endothelial cells (HUVEC) and a human hepatic cancer cell line (HepG-2) exposed to FDP-NV-800 in vitro at exposure levels within the pharmacokinetics (Cmax and the nadir) previously reported in vivo. METHODS: Diverse cellular and biochemical functions were monitored, which cumulatively can provide insights into some vital cellular functions. Cell proliferation and migration were assessed by quantitative microscopy. Mitochondrial metabolic functions were tested by the MTT assay, and cytosolic esterase activity was studied by the calcein AM assay. Chaperons (CHOP), BiP and apoptosis (caspase-3 activation) were monitored by using Western blot (WB). MAPK Erk1/2 signaling was assessed by the detection of the phosphorylated form of the protein (P-Erk 1/2) and its translocation into the cell nucleus. RESULTS: At all concentrations tested (0.001-0.1mg/mL), FDP-NV did not affect any of the biomarkers of cell integrity of HepG2 cells. In contrast, the proliferation of HUVEC was affected at the highest concentration tested (0.1mg/mL, Cmax). Exposure of HUVEC to (0.01 mg/mL) FDP-NV had a mild-moderate effect on cell proliferation as evident in the MTT assay and was absent when proliferation was assessed by direct cell counting or by using the calcein AM assays. In both cell types, exposure to the highest concentration (0.1 mg/mL) of FDP-NV did neither affect FBS-stimulated cell signaling (MAPK Erk1/2 phosphorylation) nor did it activate of Caspase 3. CONCLUSION: Our data suggest that FDP-NV-800nm are largely biocompatible with HepG-2 cells proliferation within the pharmacokinetic data reported previously. In contrast, HUVEC proliferation at the highest exposure dose (0.1 mg/mL) responded adversely with respect to several biomarkers of cell integrity. However, since the Cmax levels are very short-living, the risk for endothelial injury is likely minimal for slow rate cell proliferation such as endothelial cells.

The Use of Near-Infrared Light-Emitting Fluorescent Nanodiamond Particles to Detect Ebola Virus Glycoprotein: Technology Development and Proof of Principle.

BACKGROUND: There is a dire need for rapid diagnostic tests of high sensitivity, efficiency, and point-of-test reporting capability to mitigate lethal viral epidemic outbreaks. PURPOSE: To develop a new operating system within the lateral flow assay (LFA) format for Ebola virus (EBOV), based on fluorescent nanodiamond particles (FNDP) nitrogen vacancy (NV) emitting near-infrared (NIR) light. Specifically, we aimed to detail technical issues and the feasibility of mobilizing FNDP-NV on nitrocellulose membranes (NCM) and capturing them at test and control lines. METHODS: FNDP-NV-200nm, 400nm or 800nm were linked to anti-EBOV glycoprotein (GP) monoclonal antibodies (mAb) and tested for LFA performance by monitoring NIR emissions using an in vivo imaging system or optoelectronic device (OED). Anti-EBOV recombinant glycoprotein (GP) humanized mAb c13C6 was linked to FNDP-NV-200nm for the mobile phase; and a second anti-GP mouse mAb, 6D8, was printed on NCM at the test line. Goat anti-human IgG (GAH-IgG) served as a nonspecific antibody for conjugated FNDP-NV-200nm at the control line. RESULTS: FNDP-NV-200nm-c13C6 specifically and dose-dependently bound to recombinant EBOV GP in vitro and was effectively captured in a sandwich configuration at the test line by mAb 6D8. FNDP-NV-200nm-c13C6 was captured on the control line by GAH-IgG. The OED quantitative analysis of NIR (obtained in less than 1 minute) was further validated by an in vivo imaging system. CONCLUSION: FNDP-NV-200nm performance as a reporter for EBOV GP rapid diagnostic tests suggests an opportunity to replace contemporary visual tests for EBOV GP and other highly lethal viral pathogens. Mobile, battery-operated OED adds portability, quantitative data, rapid data collection, and point-of-test reporting capability. Further development of FNDP-NV-200nm within a LFA format is justified.

Translational medicine for stroke drug discovery: the pharmaceutical industry perspective.

Over the past 20 years, an estimated $1 billion has been spent in research and development of stroke therapeutics; however, this huge investment has failed to produce a clinically efficacious drug with the exception of the thrombolytic agent Activase (tPA). This sobering reality has been the subject of numerous reflections by renowned leaders in stroke research with special focus on the most recent failed clinical trials. The validity of the neuroprotection strategy has been questioned and efforts to substantially modify the quality of stroke research have been examined. The consistent failures of the pharmaceutical industry to develop a neuroprotective drug for ischemic stroke have had a major impact on the assessment of stroke as an attractive therapeutic area for drug discovery. Many pharmaceutical companies have scaled down their stroke programs, reflecting skepticism about the prospect of contemporary stroke drug discovery strategy based on neuroprotective agents. In this article, we present a Translational Medicine perspective on critical issues that the pharmaceutical industry and the academic community encounter but often ignore during stroke therapeutic development. This Translational Medicine framework offers a systematic analysis of the possible deficiencies that likely underwrote the colossal failure of clinical trials with neuroprotective drugs. In addition, we offer a biomarker-based system that aims at providing "proof of concept" along the discovery and development pipeline, which if implemented along early preclinical and clinical development phases, might significantly reduce risks and enable success.

Pharmacologic interventions for stroke: looking beyond the thrombolysis time window into the penumbra with biomarkers, not a stopwatch.

BACKGROUND AND PURPOSE: The majority of pharmacological agents for stroke were developed based on the assumption that neurological deficits will be reduced upon the successful interruption of biochemical mechanisms leading to neuronal death. Despite significant evidence of preclinical efficacy, none of these agents succeeded. They either failed to demonstrate efficacy in the clinic or their development was halted for safety, strategic, or commercial reasons. SUMMARY OF REVIEW: This "neuroprotection strategy" has focused primarily on targets in the neurotoxic environment that occurs under ischemic conditions. In many cases, these agents were designed to tackle events that are known to start almost immediately after onset of ischemia, which is far before a realistic therapeutic time window opens for most, if not all, patients with stroke. In other instances, they were evaluated beyond a realistic timeframe in which one could expect significant salvageable tissue or penumbra to exist. Surprisingly, most of these agents were not evaluated in conjunction with strategies for improving perfusion to the affected tissue, indicating an overoptimistic assumption that neuroprotection alone could be sufficient to halt injury caused by an abrupt interruption of brain blood flow. CONCLUSIONS: We provide a constructive translational medicine perspective about how one could improve the drug development process with the hope that the probability for success can increase in our quest to establish a novel therapy for stroke.

Update of the stroke therapy academic industry roundtable preclinical recommendations.

The initial Stroke Therapy Academic Industry Roundtable (STAIR) recommendations published in 1999 were intended to improve the quality of preclinical studies of purported acute stroke therapies. Although recognized as reasonable, they have not been closely followed nor rigorously validated. Substantial advances have occurred regarding the appropriate quality and breadth of preclinical testing for candidate acute stroke therapies for better clinical translation. The updated STAIR preclinical recommendations reinforce the previous suggestions that reproducibly defining dose response and time windows with both histological and functional outcomes in multiple animal species with appropriate physiological monitoring is appropriate. The updated STAIR recommendations include: the fundamentals of good scientific inquiry should be followed by eliminating randomization and assessment bias, a priori defining inclusion/exclusion criteria, performing appropriate power and sample size calculations, and disclosing potential conflicts of interest. After initial evaluations in young, healthy male animals, further studies should be performed in females, aged animals, and animals with comorbid conditions such as hypertension, diabetes, and hypercholesterolemia. Another consideration is the use of clinically relevant biomarkers in animal studies. Although the recommendations cannot be validated until effective therapies based on them emerge from clinical trials, it is hoped that adherence to them might enhance the chances for success.

The development of stroke therapeutics: promising mechanisms and translational challenges.

Ischemic stroke is the second most common cause of death worldwide and a major cause of disability. Intravenous thrombolysis with rt-PA remains the only available acute therapy in patients who present within 3h of stroke onset other than the recently approved mechanical MERCI device, substantiating the high unmet need in available stroke therapeutics. The development of successful therapeutic strategies remains challenging, as evidenced by the continued failures of new therapies in clinical trials. However, significant lessons have been learned and this knowledge is currently being incorporated into improved pre-clinical and clinical design. Furthermore, advancements in imaging technologies and continued progress in understanding biological pathways have established a prolonged presence of salvageable penumbral brain tissue and have begun to elucidate the natural repair response initiated by ischemic insult. We review important past and current approaches to drug development with an emphasis on implementing principles of translational research to achieve a rigorous conversion of knowledge from bench to bedside. We highlight current strategies to protect and repair brain tissue with the promise to provide longer therapeutic windows, preservation of multiple tissue compartments and improved clinical success.

Translational medicine--a paradigm shift in modern drug discovery and development: the role of biomarkers.

The success rate of novel medical entities that are submitted for registration by the regulatory agencies and followed successful marketing has been stagnating for the past decade. Failure in efficacy and safety continue to be the prime hurdles and causes of failure. Translational medicine is a new function within the pharmaceutical industry R&D organization aimed to improve the predictability and success of drug discovery and development. Biomarkers are the essence of the translational medicine strategy focus on disease biomarker, patient selection, pharmacodynamic responses (efficacy and safety) target validation, compound-target interaction). Successful deployment of biomarkers research, validation and implementation is adopted and embraced as key strategy to improved the drug discovery and development towards new medical entities.

Biocompatibility studies of fluorescent diamond particles-(NV)~800nm (part V): in vitro kinetics and in vivo localization in rat liver following long-term exposure.

BACKGROUND: We recently reported on long-term comprehensive biocompatibility and biodistribution study of fluorescent nanodiamond particles (NV)-Z-average 800nm (FNDP-(NV)) in rats. FNDP-(NV) primary deposition was found in the liver, yet liver function tests remained normal. PURPOSE: The present study aimed to gain preliminary insights on discrete localization of FNDP-(NV) in liver cells of the hepatic lobule unit and venous micro-vasculature. Kinetics of FDNP-(NV) uptake into liver cells surrogates in culture was conducted along with cell cytokinesis as markers of cells' viability. METHODS: Preserved liver specimens from a pilot consisting of two animals which were stained for cytoskeletal elements (fluorescein-isothiocyanate-phalloidin) were examined for distribution of FNDP-(NV) by fluorescent microscopy (FM) and Confocal-FM (CFM) using near infra-red fluorescence (NIR). Hepatocellular carcinoma cells (HepG-2) and human umbilical vein endothelial cells (HUVEC) were cultured with FNDP-(NV) and assayed for particle uptake and location using spectrophotometric technology and microscopy. RESULTS: HepG-2 and HUVEC displayed rapid (<30 mins) onset and concentration-dependent FNDP-(NV) internalization and formation of peri-nuclear corona. FM/CFM of liver sections revealed FNDP-(NV) presence throughout the hepatic lobules structures marked by spatial distribution, venous microvascular spaces and parenchyma and non-parenchyma cells. CONCLUSION: The robust presence of FNDP-(NV) throughout the hepatic lobules including those internalized within parenchyma cells and agglomerates in the liver venous micro-circulation were not associated with macro or micro histopathological signs nor vascular lesions. Cells cultures indicated normal cytokinesis in cells containing FNDP-(NV) agglomerates. Liver parenchyma cells and the liver microcirculation remain agnostic to presence of FNDP-(NV) in the sinusoids or internalized in the hepatic cells.

Long-term biocompatibility of fluorescent diamonds-(NV)-Z~800 nm in rats: survival, morbidity, histopathology, particle distribution and excretion studies (part IV).

BACKGROUND: Thromboembolic events are a major cause of heart attacks and strokes. However, diagnosis of the location of high risk vascular clots is hampered by lack of proper technologies for their detection. We recently reported on bio-engineered fluorescent diamond-(NV)-Z~800nm (FNDP-(NV)) conjugated with bitistatin (Bit) and proven its ability to identify iatrogenic blood clots in the rat carotid artery in vivo by Near Infra-Red (NIR) monitored by In Vivo Imaging System (IVIS). PURPOSE: The objective of the present research was to assess the in vivo biocompatibility of FNDP-(NV)-Z~800nm infused intravenously to rats. Multiple biological variables were assessed along this 12 week study commissioned in anticipation of regulatory requirements for a long-term safety assessment. METHODS: Rats were infused under anesthesia with aforementioned dose of the FNDP-(NV), while equal number of animals served as control (vehicle treated). Over the 12 week observation period rats were tested for thriving, motor, sensory and cognitive functions. At the termination of study, blood samples were obtained under anesthesia for comprehensive hematology and biochemical assays. Furthermore, 6 whole organs (liver, spleen, brain, heart, lung and kidney) were collected and examined ex vivo for FNDP-NV) via NIR monitored by IVIS and histochemical inspection. RESULTS: All animals survived, thrived (no change in body and organ growth). Neuro-behavioral functions remain intact. Hematology and biochemistry (including liver and kidney functions) were normal. Preferential FNDP-(NV) distribution identified the liver as the main long-term repository. Certified pathology reports indicated no outstanding of finding in all organs. CONCLUSION: The present study suggests outstanding biocompatibility of FNDP-(NV)-Z~800nm after long-term exposure in the rat.