Synthesis and structure-affinity relationships of novel dibenzylideneacetone derivatives as probes for β-amyloid plaques

A new and extensive set of dibenzylideneacetone derivatives was synthesized and screened for affinity toward Aβ(1-42) aggregates. Structure-activity relationships revealed the binding of dibenzylideneacetones to be affected by various substituents. The introduction of a substituent group in the ortho position reduced or abolished the binding. However, the para position was highly tolerant of sterically demanding substitutions. Three radioiodinated ligands (6, 70, and 71) and two (18)F fluoro-pegylated (FPEG) ligands (83 and 85) were prepared, all of which displayed high affinity for Aβ(1-42) aggregates (K(i) ranging from 0.9 to 7.0 nM). In biodistribution experiments, they exhibited good initial penetration (1.59, 4.68, 4.56, 4.13, and 5.15% ID/g, respectively, at 2 min) of and fast clearance from the brain. Autoradiography with sections of postmortem AD brain and transgenic mouse brain confirmed the high affinity of these tracers. These preliminary results strongly suggest the dibenzylideneacetone structure to be a potential new scaffold for β-amyloid imaging probes.     

Current status of β-blockers for the treatment of hypertension: an update

β-Adrenoceptor blockers (β-blockers) are one of the oldest classes of cardiovascular drugs still in use. Several short- and long-term clinical outcomes studies have demonstrated their effectiveness and safety for the treatment of hypertension, coronary artery disease, myocardial infarction, heart failure and sudden cardiac death. Due to their safety and efficacy, β-blockers have been recommended by several national and international committees as first-line therapy of hypertension. However, despite their proven benefits, their use as first-line treatment for hypertension has come under criticism lately. Because of these recent developments, several authors have recommended that β-blockers no longer be used as first-line therapy for hypertension. In this review, evidence-based information will be presented, which will demonstrate that β-blockers are an effective and safe class of antihypertensive and cardiovascular drugs for most patients with the exception of black and elderly hypertensive patients in whom the β-blockers are less effective compared to other classes of drugs. In addition, evidence will be presented from several major meta-analyses that β-blockers are equally effective in reducing blood pressure and cardiovascular complications. This review will also discuss differences in the mechanism of action of older and newer (third-generation) β-blockers and provide evidence that newer agents should be preferred over the older ones in the treatment of hypertensive patients with certain comorbidities.     

Technetium-99m labeled pyridyl benzofuran derivatives as single photon emission computed tomography imaging probes for β-amyloid plaques in Alzheimer's brains

Three novel (99m)Tc-labeled pyridyl benzofuran derivatives were tested as potential probes for imaging β-amyloid plaques using single photon emission computed tomography (SPECT). The (99m)Tc and corresponding rhenium complexes were synthesized with bis(aminoethanethiol) (BAT) as a chelating ligand. All Re complexes showed affinity for Aβ(1-42) aggregates (K(i) = 13.6-149.6 nM). Biodistribution experiments in normal mice revealed that the (99m)Tc-labeled derivatives displayed sufficient uptake in the brain (1.41-1.80% ID/g at 2 min postinjection). Notably, [(99m)Tc]BAT-Bp-2 showed a good initial uptake (1.80% ID/g at 2 min) and a reasonable washout from the brain (0.79% ID/g at 60 min). Ex vivo autoradiography with [(99m)Tc]BAT-Bp-2 revealed substantial labeling of β-amyloid plaques in sections of brain tissue from Tg2576 transgenic mice but not in the age-matched controls. [(99m)Tc]BAT-Bp-2 may be a potential SPECT probe for imaging β-amyloid plaques in Alzheimer's brains.     

Multi-fluorine labeled indanone derivatives as potential MRI imaging probes for β-Amyloid plaques

In order to realize the early diagnosis of Alzheimer's disease (AD), we designed and synthesized a series of multi-fluorine labeled indanone derivatives based on indanone which could target β-amyloid (Aβ). Through the in vitro staining experiment and affinity experiment, we selected 7d out, and then evaluated it through other in vivo and in vitro experiments. The staining of AD human brain adjacent sections revealed that compound 7d could bind to Aβ plaques with high affinity. In the in vitro binding assay, 7d showed a balanced affinity with Aβ1–40 (K_d = 367 ± 13) and Aβ1–42 (K_d = 384 ± 56). Also, 7d exhibited a low toxicity (LD50 > 50 mg/kg) and an excellent ability to pass through the blood–brain barrier (Log p = 3.87). The biodistribution experiment in mice showed that 7d reached the highest brain uptake after 1 h of tail vein injection and cleared after 24 h. A low concentration of 7d (1.875 mg/ml) showed a strong imaging ability (19F-weighted mode), and the imaging capability increased with the increasing of concentration. All the results showed that 7d could provide a feasible solution for the early diagnosis of AD under non-radioactive condition.     

Near-infrared fluorescent probes for imaging of amyloid plaques in Alzheimer?s disease

One of the early pathological hallmarks of Alzheimer׳s disease (AD) is the deposition of amyloid-β (Aβ) plaques in the brain. There has been a tremendous interest in the development of Aβ plaques imaging probes for early diagnosis of AD in the past decades. Optical imaging, particularly near-infrared fluorescence (NIRF) imaging, has emerged as a safe, low cost, real-time, and widely available technique, providing an attractive approach for in vivo detection of Aβ plaques among many different imaging techniques. In this review, we provide a brief overview of the state-of-the-art development of NIRF Aβ probes and their in vitro and in vivo applications with special focus on design strategies and optical, binding, and brain-kinetic properties.KEY WORDS: Alzheimer׳s disease, Blood-brain barrier, Fluorescence probe, Near-infrared fluorescence, Optical imaging, Amyloid-β plaguesAbbreviations: Aβ, amyloid-β, Ach, acetylcholine, AD, Alzheimer’s disease, APP, amyloid peptide precursor, BAP, BODIPY-based Ab imaging probe, BBB, blood-brain barrier, Cy, cyanine dyes, ICG, indocyanine green dyes, MRI, magnetic resonance imaging, NIR, near-infrared, NIRF, near-infrared fluorescence, PET, positron emission tomography, ROS, reactive oxygen species, SPECT, single photon emission computed tomography     

Current status of HTRF® technology in kinase assays

Background: Homogeneous time-resolved fluorescence (HTRF) is a fluorescence resonance energy transfer-based technology used to measure bimolecular interactions. It has been applied successfully to kinase assays and has become an important tool in kinase drug discovery. Objective: This article reviews the current status of HTRF technology in biochemical and cellular kinase assays. Methods: Recent literature and meeting reports on HTRF kinase assays are reviewed, and their principles, advantages and drawbacks, current status and the potential applications in kinase drug discovery are discussed. Results/conclusion: HTRF kinase assays are homogeneous, robust, sensitive, easy to miniaturize and high-throughput. This assay format is versatile, as both peptide and protein substrates can be used, and high ATP concentrations are tolerated, which enables the assay to be performed under conditions mimicking the physiological environment. HTRF kinase assays have been applied to both high-throughput screening and compound mechanistic studies. Besides protein kinases, the technology has now been expanded into the lipid kinase family. Furthermore, the utility of HTRF technology in cellular assays is emerging. HTRF kinase assays are a great addition to the toolbox for kinase drug discovery.     

Animal models of idiosyncratic drug-induced liver injury—Current status

The infrequent occurrence of idiosyncratic reactions and their dependence on individual sensitivity factors allow them to go undetected in current preclinical safety evaluation using conventional animal tests. Better predictive models for idiosyncratic, drug-induced liver injury (IDILI) would enable the preclinical elimination of drug candidates with idiosyncrasy liability and could provide evidence for a mode of action for these responses, suggest early biomarkers of IDILI, and lead to the development of mechanism-based, in vitro screens. Desirable characteristics of an animal model include the production of liver injury in a large fraction of animals of relatively inexpensive species/strains and the ability to distinguish drugs that cause IDILI in humans from ones that do not. The mechanistic basis for idiosyncratic reactions remains poorly understood. However, attempts at animal model development have been made based on several hypothesized modes of action of IDILI. These hypotheses have centered on drug disposition polymorphisms, adaptive immunity, mitochondrial dysfunction, failure to adapt to modest injury, inflammatory stress, and multiple determinants, and the success in achieving animal models of liver injury for each of these is discussed. Despite numerous challenges associated with animal models of IDILI, some models have emerged and are proving useful in exploring potential mechanisms. Current animal models are not perfect, but they hold promise for increasing the prediction and understanding of human idiosyncratic drug reactions.     

Novel 18F-labeled benzofuran derivatives with improved properties for positron emission tomography (PET) imaging of β-amyloid plaques in Alzheimer's brains

In vivo imaging of β-amyloid plaques in the brain may lead to the early diagnosis of Alzheimer's disease (AD) and monitoring of the progression and effectiveness of treatment. In the present study, we report on the development of two potential PET probes, [(18)F]FPYBF-2 ([(18)F]10) and [(18)F]FPHBF-2 ([(18)F]21), for imaging of β-amyloid plaques in AD brain. In experiments in vitro, 10 and 21 displayed high affinity for Aβ(1-42) aggregates (K(i) = 2.41 and 3.85 nM, respectively). In biodistribution experiments using normal mice, they displayed high uptake in the brain (7.38 and 8.18%?ID/g at 2 min postinjection, respectively), and the radioactivity washed out from the brain rapidly (3.15 and 3.87%?ID/g at 60 min postinjection, respectively), which is highly desirable for β-amyloid imaging agents. In vivo, they clearly labeled β-amyloid plaques in Tg2576 mice. Furthermore, the specific labeling of β-amyloid plaques by 10 and 21 was observed in autoradiographs of sections of autopsied AD brain. These new fluorinated benzofuran derivatives are promising PET probes for imaging cerebral β-amyloid plaques.     

The profile of β-amyloid precursor protein expression of rats induced by aluminum

The environmental agent aluminum has been extensively investigated for a potential relationship with amyloid precursor protein (APP) expression. Despite many investigations, there is at present no definite proof from which to draw a conclusion. Since APP is an integral membrane protein expressed in different tissues and capable of fluxes across the blood-brain barrier (BBB), which may ultimately affect APP level in brain, it is necessary to assess the expression profile among vital body organs. The present study compared aluminum oxide and aluminum chloride injected rats with control rats (saline treated) to observe if aluminum affected APP expression patterns in different organs by immunohistochemistry (IHC). The expression of APP was observed in the brain of aluminum chloride treated rats and in the liver of aluminum oxide injected group. Results of double IHC staining showed that it is Kupffer cells, which are located in liver sinus and expressed APP after aluminum oxide treatment. Oxidative stress is suggested as the potential pathway that aluminum chloride exert effects in brain. These results suggest that different aluminum compounds may impact the expression of APP in brain and liver tissues. The mechanism that aluminum induced liver APP expression still needs further investigation.     

Design of β-amyloid aggregation inhibitors from a predicted structural motif

Drug design studies targeting one of the primary toxic agents in Alzheimer's disease, soluble oligomers of amyloid β-protein (Aβ), have been complicated by the rapid, heterogeneous aggregation of Aβ and the resulting difficulty to structurally characterize the peptide. To address this, we have developed [Nle(35), D-Pro(37)]Aβ(42), a substituted peptide inspired from molecular dynamics simulations which forms structures stable enough to be analyzed by NMR. We report herein that [Nle(35), D-Pro(37)]Aβ(42) stabilizes the trimer and prevents mature fibril and β-sheet formation. Further, [Nle(35), D-Pro(37)]Aβ(42) interacts with WT Aβ(42) and reduces aggregation levels and fibril formation in mixtures. Using ligand-based drug design based on [Nle(35), D-Pro(37)]Aβ(42), a lead compound was identified with effects on inhibition similar to the peptide. The ability of [Nle(35), D-Pro(37)]Aβ(42) and the compound to inhibit the aggregation of Aβ(42) provides a novel tool to study the structure of Aβ oligomers. More broadly, our data demonstrate how molecular dynamics simulation can guide experiment for further research into AD.     

Current status of drug receptor nomenclature: receptor closure? The role of NC-IUPHAR

Pharmacology is at a crucial point, because we now have access to sequences, by homology, for almost all of the receptors in the human genome. The International Union of Pharmacology Committee on Receptor Nomenclature and Drug Classification (NC-IUPHAR) has set up > 50 subcommittees to define the receptors, and their recommendations, when approved, are posted on a website freely available to all scientists. A major new effort is to functionally define relevant receptor polymorphisms. This initiative is open to all, and works only because of the freely given voluntary effort of scientists.     

Current status of drug receptor nomenclature: receptor closure? The role of NC-IUPHAR

Pharmacology is at a crucial point, because we now have access to sequences, by homology, for almost all of the receptors in the human genome. The International Union of Pharmacology Committee on Receptor Nomenclature and Drug Classification (NC-IUPHAR) has set up > 50 subcommittees to define the receptors, and their recommendations, when approved, are posted on a website freely available to all scientists. A major new effort is to functionally define relevant receptor polymorphisms. This initiative is open to all, and works only because of the freely given voluntary effort of scientists.     

Current status in research of dengue vaccine candidates based on domain Ⅲof E protein

The ideal dengue vaccines should be low reactogenic, induce life-long protection against infection with any of the four serotypes of dengue viruses, and be affordable. The envelope protein domain Ⅲ of dengue virus has been implicated in receptor binding, and it is also the target of specific neutralizing antibodies.In this article, the current state of knowledge on vaccine candidates based on domain Ⅲ is reviewed.     

Current trends in β-lactam based β-lactamases inhibitors

The introduction of antibiotics to treat bacterial infections either by killing or blocking their growth has been accompanied by the development of resistance mechanism that allows the bacteria to survive and proliferate. In particular the successive series of β-lactams have selected several generations of β-lactamases including ESBLs, AmpC β-lactamases, KPC carbapenamases in Enterobacteriaceae, the metallo β-lactamases VIMs and IMPs, and very recently the threatening NDM-1 that confers resistance to virtually any clinically used antibiotic. The increasing use of carbapenems due to the spread of resistance to other existing antibacterial agents has facilitated the spread of resistance, especially in Acinetobacter spp. due to OXA- and metallo-carbapenemases. The pharmaceutical industry, that abandoned this field at the end of the nineties, is now trying to recover by developing some novel β-lactam antibiotics and novel β-lactamase-inhibitors, the latter to be used in combination with new as well as seasoned β-lactam antibiotics. This article provides a survey of patent and scientific literature for β-lactamase inhibitors discovered in the period 2006-2010.     

Synthesis and evaluation of 11C-labeled imidazo[2,1-b]benzothiazoles (IBTs) as PET tracers for imaging β-amyloid plaques in Alzheimer's disease

We report a novel series of (11)C-labeled imidazo[2,1-b]benzothiazoles (IBTs) as tracers for imaging of cerebral β-amyloid (Aβ) deposits in patients with Alzheimer's disease (AD) by means of positron emission tomography (PET). From a series of 11 compounds, candidates were identified to have a high binding affinity for Aβ. Selected compounds were prepared as O- or N-[(11)C]methyl derivatives and shown to have a high initial brain uptake in wild-type mice (range 1.9-9.2% I.D./g at 5 min). 2-(p-[(11)C]Methylaminophenyl)-7-methoxyimidazo[2,1-b] benzothiazole ([(11)C]5) was identified as a lead based on the combined favorable properties of high initial brain uptake, rapid clearance from normal brain, and high in vitro affinity for Aβ(1-40) (K(i) = 3.5 nM) and Aβ(1-42) (5.8 nM), which were superior to the Pittsburgh compound B (1a). In an APP/PS1 mouse model of AD (Tg), we demonstrate a specific uptake of [(11)C]5 in Aβ-containing telencephalic brain regions by means of small-animal PET that was confirmed by regional brain biodistribution, ex vivo autoradiography, and immunohistochemistry. Analysis of brain sections of Tg mice receiving a single bolus injection of [(11)C]5 and [(3)H]1a together revealed that the tracers bind to Aβ plaques in the brain of Tg mice in a comparable pattern. Taken together, these data suggest that IBTs represent useful PET imaging agents for high-sensitivity detection of Aβ plaques.     

Selective dihydropyiridine compounds facilitate the clearance of β-amyloid across the blood-brain barrier

Increasing evidence suggests that the soluble form of the β-amyloid peptide (Aβ) plays a critical role in the pathogenesis of Alzheimer's disease. Previously, we reported that treatment with certain antihypertensive dihydropyridine (DHP) compounds can mitigate Aβ production in whole cells and reduce brain Aβ burden in a mouse model of Alzheimer's disease. As Aβ clearance across the blood-brain barrier (BBB) is a key regulatory step in the deposition of Aβ in the brain, we examined the effect of DHP treatment on Aβ brain clearance. Treatment with certain DHP compounds significantly increased Aβ(1-42) transcytosis across the BBB in an in vitro model. The rank order of these compounds was nitrendipine>nicardipine=cilnidipine=lercanidipine>nimodipine>azelnidipine=nilvadipine. Conversely, amlodipine, felodipine, isradipine, and nifedipine had no effect on Aβ(1-42) BBB transcytosis. In an in vivo paradigm of Aβ clearance across the BBB, peripheral administration of nitrendipine, cilnidipine, and nilvadipine to wild-type animals facilitated the brain clearance of centrally administered exogenous Aβ(1-42), whereas with amlodipine, there was no effect. We also observed improved cognitive function in mice treated with nilvadipine following central Aβ(1-42) insult. Thus, in addition to the effect of certain DHP compounds on Aβ production, we demonstrate that certain DHP compounds also facilitate the clearance of Aβ across the BBB. This dual mechanism of action may be particularly effective in attenuating Aβ brain burden in Alzheimer's disease and could open the door to a new class of therapies for the treatment of this disease.     

Current status of hepatocellular carcinoma treatment in Japan: practical use of sorafenib (nexavar®)

The efficacy of sorafenib in hepatocellular carcinoma (HCC) has been demonstrated in two pivotal clinical trials: the European SHARP trial and a second trial that recruited patients in the Asia-Pacific region. Sorafenib was approved for the treatment of advanced HCC in Japan based on the results of these studies. This article presents experiences with sorafenib in patients with HCC at three institutions in Japan, representing the viewpoints of a liver surgeon and a hepatologist at university hospitals, and a hepatologist at a community hospital. The three physicians discuss representative cases and current clinical practice at their institutions, and their recommendations for the use of sorafenib in the wider clinical setting. Overall, the experiences at these institutions show that sorafenib is most effective when administered for a long time, and the management of adverse events (AEs) [including dose-reduction and modification] is critical to achieving high levels of adherence to treatment. A team-focussed treatment strategy that includes patient counselling and follow-up can contribute to managing AEs to ensure successful continuation of sorafenib therapy. In addition, a proposed definition of unresponsiveness to transarterial chemoembolization and the implications of treatment lag on the outcomes of sorafenib therapy, as well as measures for the prevention and treatment of hand-foot skin reaction are discussed.