Photodynamic therapy : a pathway for enhanced delivery of liposomal doxorubicin to tumors

Abstract Part I : Background : Isolated lung perfusion (ILP) was designed for the treatment of loco-regional malignancies of the lung. In contrast to intravenous (IV) drug application, ILP allows for a selective administration of cytostatic agents such as doxorubicin to the lung while sparing non-affected tissues. However, the clinical results with ILP were disappointing. Doxorubicinbased ILP on sarcoma rodent lungs suggested high overall doxorubicin concentrations within the perfused lung but a poor penetration of the cytostatic agent into tumors. The same holds true for liposomal-encapsulated macromolecular doxorubicin (LiporubicinTM) In specific conditions, low-dose photodynamic therapy (PDT) can enhance the distribution of macromolecules across the endothelial bamer in solid tumors. It was recently postulated that tumor neovessels were more responsive to PDT than the normal vasculature. We therefore hypothesized that Visudyne®-mediated PDT could selectively increase liposomal doxorubicin (LiporubicinTM) uptake in sarcoma tumors to rodent lungs during intravenous (IV) drug administration and isolated lung perfusion (ILP). Material and Methods : A sarcoma tumor was generated in the left lung of Fisher rats by subpleural injection of a sarcoma cell ,suspension via thoracotomy. Ten days later, LiporubicinTM is administered IV or by single pass antegrade ILP, with or without Visudyne® -mediated low-dose PDT pre-treatment of the sarcoma bearing lung. The drug concentration and distribution were assessed separately in tumors and lung tissues by high pressure liquid chromatography (HPLC) and fluorescence microscopy (FNI~, respectively. Results : PDT pretreatment before IV LiporubicinTM administration resulted in a significantly higher tumor drug uptake and tumor to lung drug ratio compared to IV drug injection alone without affecting the blood flow and drug distribution in the lung. PDT pre-treatment before LiporubicinTM-based ILP also resulted in a higher tumor drug uptake and a higher tumor to lung drug ratio compared to ILP alone, however, these differences were not significant due to a heterogeneous blood flow drug distribution during ILP which was further accentuated by PDT. Conclusions : Low-dose Visudyne®-mediated PDT pre-treatment has the potential to selectively enhance liposomal encapsulated doxorubicin uptake in tumors but not in normal lung tissue after IV drug application in a rat model of sarcoma tumors to the lung which opens new perspectives for the treatment of superficially spreading chemoresistant tumors of the chest cavity such as mesothelioma or malignant effusion. However, the impact of PDT on macromolecular drug uptake during ILP is limited since its therapeutic advantage is circumvented by ILP-induced heterogeneicity of blood flow and drug distribution Abstract Part II Background : Photodynamic therapy (PDT) with Visudyne® acts by direct cellular phototoxicity and/or by an indirect vascular-mediated effect. Here, we demonstrate that the vessel integrity interruption by PDT can promote the extravasation of a macromolecular agent in normal tissue. To obtain extravasation in normal tissue PDT conditions were one order of magnitude more intensive than the ones in tissue containing neovessels reported in the literature. Material and Methods : Fluorescein isothiocyanate dextran (FITC-D, 2000kDa), a macromolecular agent, was intravenously injected 10 minutes before (LKO group, n=14) or 2 hours (LK2 group, n=16) after Visudyne® mediated PDT in nude mice bearing a dorsal skin fold chamber. Control animals had no PDT (CTRL group, n=8). The extravasation of FITC-D from blood vessels in striated muscle tissue was observed in both groups in real-time for up to 2500 seconds after injection. We also monitored PDT-induced leukocyte rolling in-vivo and assessed, by histology, the corresponding inflammatory reaction score in the dorsal skin fold chambers. Results : In all animals, at the applied PDT conditions, FITC-D extravasation was significantly enhanced in the PDT treated areas as compared to the surrounding non-treated areas (p<0.0001). There was no FITC-D leakage in the control animals. Animals from the LKO group had significantly less FITC-D extravasation than those from the LK2 group (p = 0.0002). In the LKO group FITC-D leakage correlated significantly with the inflammation (p < 0.001). Conclusions: At the selected conditions, Visudyne-mediated PDT promotes vascular leakage and FITC-D extravasation into the interstitial space of normal tissue. The intensity of vascular leakage depends on the time interval between PDT and FITC-D injection. This concept could be used to locally modulate the delivery of macromolecules in vivo. Résumé : La perfusion cytostatique isolée du poumon permet une administration sélective des agents cytostatiques sans implication de la circulation systémique avec une forte accumulation au niveau du poumon mais une faible pénétration dans les tumeurs. La thérapie photodynamique (PDT) qui consiste en l'application d'un sensibilisateur activé par lumière laser non- thermique d'une longueur d'onde définie permet dans certaines conditions, une augmentation de la pénétration des agents cytostatiques macromoléculaires à travers la barrière endothéliale tumorale. Nous avons exploré cet avantage thérapeutique de la PDT dans un modèle expérimental afin d'augmenter d'une manière sélective la pénétration tumorale de la doxorubicin pegylée, liposomal- encapsulée macromoléculaire (Liporubicin). Une tumeur sarcomateuse a été générée au niveau du poumon de rongeur suivie d'administration de Liporubicin, soit par voie intraveineuse soit par perfusion isolée du poumon (ILP). Une partie des animaux ont reçus un prétraitement de la tumeur et du poumon sous jacent par PDT avec Visudyne comme photosensibilisateur. Les résultats ont démontrés que la PDT permet, sous certaines conditions, une augmentation sélective de Liporubicin dans les tumeurs mais pas dans le parenchyme pulmonaire sous jacent. Après administration intraveineuse de Liporubicin et prétraitement par PDT, l'accumulation dans les tumeurs était significative par rapport au poumon, et aux tumeurs sans PDT. Le même phénomène est observé après ILP du poumon. Cependant, les différences avec ou sans PDT n'étaient pas significatives lié à und distribution hétérogène de Liporubicin dans le poumon perfusé après ILP. Dans une deuxième partie de l'expérimentation, nous avons exploré la microscopie intra-vitale pour déterminer l'extravasion des substances macromoléculaires (FITS) à travers la barrière endothéliale avec ou sans Visudyne-PDT au niveau des chambres dorsales des souris nues. Les résultats montrent qu'après PDT, l'extravasion de FITS a été augmentée de manière significative par rapport au tissu non traité. L'intensité de l'extravasion de FITS dépendait également de l'intervalle entre PDT et injection de FITS. En conclusion, les expérimentations montrent que la PDT est capable, sous certaines conditions, d'augmenter de manière significative l'extravasion des macromolécules à travers la barrière endothéliale et leur accumulation dans des tumeurs mais pas dans le parenchyme pulmonaire. Ces résultats permettent une nouvelle perspective de traitement pour des tumeurs superficielles intrathoraciques chimio-résistent comme l'épanchement pleural malin ou le mésothéliome pleural.

The use of the likelihood ratio for evaluative and investigative purposes in comparative forensic handwriting examination

This paper extends previous research and discussion on the use of multivariate continuous data, which are about to become more prevalent in forensic science. As an illustrative example, attention is drawn here on the area of comparative handwriting examinations. Multivariate continuous data can be obtained in this field by analysing the contour shape of loop characters through Fourier analysis. This methodology, based on existing research in this area, allows one describe in detail the morphology of character contours throughout a set of variables. This paper uses data collected from female and male writers to conduct a comparative analysis of likelihood ratio based evidence assessment procedures in both, evaluative and investigative proceedings. While the use of likelihood ratios in the former situation is now rather well established (typically, in order to discriminate between propositions of authorship of a given individual versus another, unknown individual), focus on the investigative setting still remains rather beyond considerations in practice. This paper seeks to highlight that investigative settings, too, can represent an area of application for which the likelihood ratio can offer a logical support. As an example, the inference of gender of the writer of an incriminated handwritten text is forwarded, analysed and discussed in this paper. The more general viewpoint according to which likelihood ratio analyses can be helpful for investigative proceedings is supported here through various simulations. These offer a characterisation of the robustness of the proposed likelihood ratio methodology.

Oxidative potential of a panel of carbonaceous and metallic nanoparticles

Characterisation of nanoparticles (NP) based on size distribution, surface area, reactivity, and aggregation status of nanoparticles (NP) are of prime importance because they are usually closely related to toxicity. To date, most of the toxicity studies are quite time and money consuming. In the present study we report the oxidative properties of a panel of various NP (four Carbonaceous, nine Metal oxides, and one Metal as showed in Table 1) assessed with an acellular reactivity test measuring dithiothreitol (DTT) consumption (Sauvain et al. 2008). Such a test allows determining the ability of NP to catalyse the transfer of electrons from DTT to oxygen. DTT is used as a reductant species. NP were diluted and sonicated in Tween 80® to a final concentration of 50 g/mL. Printex 90 was diluted 5 times before doing the DTT assay because of its expected higher activity. Suspensions were characterised for NP size distribution by Nanoparticle Tracking Analysis (Nanosight©). Fresh solutions were incubated with DTT (100 μM). Aliquots were taken every 5 min and the remaining DTT was determined by reacting it with DTNB. The reaction rate was determined for NP suspensions and blank in parallel. The mean Brownian size distribution of NP agglomerates in suspension is presented in Table 1. D values correspond to 10th, and 50th percentiles of the particle diameters. All the NP agglomerated in Tween 80 with a D50 size corresponding to at least twice their primary size, except for Al2O3 (300 nm). The DTT test showed Printex 90 sample to be the most reactive one, followed by Diesel EPA and Nanotubes. Most of the metallic NP was nonresponding toward this test, except for NiO and Ag which reacted positively and ZnO which presented the most negative reactivity (see Figure 1). This last observation suggests that electron transfer between DTT and oxygen is hindered in presence of ZnO compared with the blank. Such "stabilization" could be attributable to ZnO dissolution and complexation between Zn2+ ions and DTT.

Quantification of in vivo short echo-time proton magnetic resonance spectra at 14.1 T using two different approaches of modelling the macromolecule spectrum

Reliable quantification of the macromolecule signals in short echo-time H-1 MRS spectra is particularly important at high magnetic fields for an accurate quantification of metabolite concentrations (the neurochemical profile) due to effectively increased spectral resolution of the macromolecule components. The purpose of the present study was to assess two approaches of quantification, which take the contribution of macromolecules into account in the quantification step. H-1 spectra were acquired on a 14.1 T/26 cm horizontal scanner on five rats using the ultra-short echo-time SPECIAL (spin echo full intensity acquired localization) spectroscopy sequence. Metabolite concentrations were estimated using LCModel, combined with a simulated basis set of metabolites using published spectral parameters and either the spectrum of macromolecules measured in vivo, using an inversion recovery technique, or baseline simulated by the built-in spline function. The fitted spline function resulted in a smooth approximation of the in vivo macromolecules, but in accordance with previous studies using Subtract-QUEST could not reproduce completely all features of the in vivo spectrum of macromolecules at 14.1 T. As a consequence, the measured macromolecular 'baseline' led to a more accurate and reliable quantification at higher field strengths.

Parts, places, and perspectives : a theory of spatial relations based an mereotopology and convexity

This thesis suggests to carry on the philosophical work begun in Casati's and Varzi's seminal book Parts and Places, by extending their general reflections on the basic formal structure of spatial representation beyond mereotopology and absolute location to the question of perspectives and perspective-dependent spatial relations. We show how, on the basis of a conceptual analysis of such notions as perspective and direction, a mereotopological theory with convexity can express perspectival spatial relations in a strictly qualitative framework. We start by introducing a particular mereotopological theory, AKGEMT, and argue that it constitutes an adequate core for a theory of spatial relations. Two features of AKGEMT are of particular importance: AKGEMT is an extensional mereotopology, implying that sameness of proper parts is a sufficient and necessary condition for identity, and it allows for (lower- dimensional) boundary elements in its domain of quantification. We then discuss an extension of AKGEMT, AKGEMTS, which results from the addition of a binary segment operator whose interpretation is that of a straight line segment between mereotopological points. Based on existing axiom systems in standard point-set topology, we propose an axiomatic characterisation of the segment operator and show that it is strong enough to sustain complex properties of a convexity predicate and a convex hull operator. We compare our segment-based characterisation of the convex hull to Cohn et al.'s axioms for the convex hull operator, arguing that our notion of convexity is significantly stronger. The discussion of AKGEMTS defines the background theory of spatial representation on which the developments in the second part of this thesis are built. The second part deals with perspectival spatial relations in two-dimensional space, i.e., such relations as those expressed by 'in front of, 'behind', 'to the left/right of, etc., and develops a qualitative formalism for perspectival relations within the framework of AKGEMTS. Two main claims are defended in part 2: That perspectival relations in two-dimensional space are four- place relations of the kind R(x, y, z, w), to be read as x is i?-related to y as z looks at w; and that these four-place structures can be satisfactorily expressed within the qualitative theory AKGEMTS. To defend these two claims, we start by arguing for a unified account of perspectival relations, thus rejecting the traditional distinction between 'relative' and 'intrinsic' perspectival relations. We present a formal theory of perspectival relations in the framework of AKGEMTS, deploying the idea that perspectival relations in two-dimensional space are four-place relations, having a locational and a perspectival part and show how this four-place structure leads to a unified framework of perspectival relations. Finally, we present a philosophical motivation to the idea that perspectival relations are four-place, cashing out the thesis that perspectives are vectorial properties and argue that vectorial properties are relations between spatial entities. Using Fine's notion of "qua objects" for an analysis of points of view, we show at last how our four-place approach to perspectival relations compares to more traditional understandings.

Population pharmacokinetic-pharmacodynamic modelling of angiotensin receptor blockade in healthy volunteers.

OBJECTIVE: To compare the pharmacokinetic and pharmacodynamic characteristics of angiotensin II receptor antagonists as a therapeutic class. DESIGN: Population pharmacokinetic-pharmacodynamic modelling study. METHODS: The data of 14 phase I studies with 10 different drugs were analysed. A common population pharmacokinetic model (two compartments, mixed zero- and first-order absorption, two metabolite compartments) was applied to the 2685 drug and 900 metabolite concentration measurements. A standard nonlinear mixed effect modelling approach was used to estimate the drug-specific parameters and their variabilities. Similarly, a pharmacodynamic model was applied to the 7360 effect measurements, i.e. the decrease of peak blood pressure response to intravenous angiotensin challenge recorded by finger photoplethysmography. The concentration of drug and metabolite in an effect compartment was assumed to translate into receptor blockade [maximum effect (Emax) model with first-order link]. RESULTS: A general pharmacokinetic-pharmacodynamic (PK-PD) model for angiotensin antagonism in healthy individuals was successfully built up for the 10 drugs studied. Representatives of this class share different pharmacokinetic and pharmacodynamic profiles. Their effects on blood pressure are dose-dependent, but the time course of the effect varies between the drugs. CONCLUSIONS: The characterisation of PK-PD relationships for these drugs gives the opportunity to optimise therapeutic regimens and to suggest dosage adjustments in specific conditions. Such a model can be used to further refine the use of this class of drugs.

The phenotype of recurrent 10q22q23 deletions and duplications.

The genomic architecture of the 10q22q23 region is characterised by two low-copy repeats (LCRs3 and 4), and deletions in this region appear to be rare. We report the clinical and molecular characterisation of eight novel deletions and six duplications within the 10q22.3q23.3 region. Five deletions and three duplications occur between LCRs3 and 4, whereas three deletions and three duplications have unique breakpoints. Most of the individuals with the LCR3-4 deletion had developmental delay, mainly affecting speech. In addition, macrocephaly, mild facial dysmorphisms, cerebellar anomalies, cardiac defects and congenital breast aplasia were observed. For congenital breast aplasia, the NRG3 gene, known to be involved in early mammary gland development in mice, is a putative candidate gene. For cardiac defects, BMPR1A and GRID1 are putative candidate genes because of their association with cardiac structure and function. Duplications between LCRs3 and 4 are associated with variable phenotypic penetrance. Probands had speech and/or motor delays and dysmorphisms including a broad forehead, deep-set eyes, upslanting palpebral fissures, a smooth philtrum and a thin upper lip. In conclusion, duplications between LCRs3 and 4 on 10q22.3q23.2 may lead to a distinct facial appearance and delays in speech and motor development. However, the phenotypic spectrum is broad, and duplications have also been found in healthy family members of a proband. Reciprocal deletions lead to speech and language delay, mild facial dysmorphisms and, in some individuals, to cerebellar, breast developmental and cardiac defects.

Handling macromolecule signals in the quantification of the neurochemical profile.

In vivo localized proton magnetic resonance spectroscopy (1H MRS) became a powerful and unique technique to non-invasively investigate brain metabolism of rodents and humans. The main goal of 1H MRS is the reliable quantification of concentrations of metabolites (neurochemical profile) in a well-defined region of the brain. The availability of very high magnetic field strengths combined with the possibility of acquiring spectra at very short echo time have dramatically increased the number of constituents of the neurochemical profile. The quantification of spectra measured at short echo times is complicated by the presence of macromolecule signals of particular importance at high magnetic fields. An error in the macromolecule estimation can lead to substantial errors in the obtained neurochemical profile. The purpose of the present review is to overview methods of high field 1H MRS with a focus on the metabolite quantification, in particular in handling signals of macromolecules. Three main approaches of handling signals of macromolecules are described, namely mathematical estimation of macromolecules, measurement of macromolecules in vivo, and direct acquisition of the in vivo spectrum without the contribution of macromolecules.

Health behaviours, socioeconomic status, and mortality: further analyses of the British Whitehall II and the French GAZEL prospective cohorts

BACKGROUND: Differences in morbidity and mortality between socioeconomic groups constitute one of the most consistent findings of epidemiologic research. However, research on social inequalities in health has yet to provide a comprehensive understanding of the mechanisms underlying this association. In recent analysis, we showed health behaviours, assessed longitudinally over the follow-up, to explain a major proportion of the association of socioeconomic status (SES) with mortality in the British Whitehall II study. However, whether health behaviours are equally important mediators of the SES-mortality association in different cultural settings remains unknown. In the present paper, we examine this issue in Whitehall II and another prospective European cohort, the French GAZEL study. METHODS AND FINDINGS: We included 9,771 participants from the Whitehall II study and 17,760 from the GAZEL study. Over the follow-up (mean 19.5 y in Whitehall II and 16.5 y in GAZEL), health behaviours (smoking, alcohol consumption, diet, and physical activity), were assessed longitudinally. Occupation (in the main analysis), education, and income (supplementary analysis) were the markers of SES. The socioeconomic gradient in smoking was greater (p<0.001) in Whitehall II (odds ratio [OR] = 3.68, 95% confidence interval [CI] 3.11-4.36) than in GAZEL (OR = 1.33, 95% CI 1.18-1.49); this was also true for unhealthy diet (OR = 7.42, 95% CI 5.19-10.60 in Whitehall II and OR = 1.31, 95% CI 1.15-1.49 in GAZEL, p<0.001). Socioeconomic differences in mortality were similar in the two cohorts, a hazard ratio of 1.62 (95% CI 1.28-2.05) in Whitehall II and 1.94 in GAZEL (95% CI 1.58-2.39) for lowest versus highest occupational position. Health behaviours attenuated the association of SES with mortality by 75% (95% CI 44%-149%) in Whitehall II but only by 19% (95% CI 13%-29%) in GAZEL. Analysis using education and income yielded similar results. CONCLUSIONS: Health behaviours were strong predictors of mortality in both cohorts but their association with SES was remarkably different. Thus, health behaviours are likely to be major contributors of socioeconomic differences in health only in contexts with a marked social characterisation of health behaviours. Please see later in the article for the Editors' Summary.

Hybrid PET/MRI in the assessment of cardiac viability: added value compared to PET/CT

Purpose: We evaluated the potential for hybrid PET/MRI devices to provide integrated metabolic, functional and anatomic characterisation of patients with suspected coronary artery disease.Methods and Materials: Ten patients (5 with suspected hibernating myocardium and 5 healthy volunteers) performed an imaging study using a hybrid PET/MRI (Philips). Viability assessed by 18F-FDG was performed in diseased patients along with MRI anatomic and functional study and reassessed within 30 minutes by conventional PET/CT. Non-contrast right coronary artery (RCA) targeted and whole heart 3D coronary angio-MRI using ECG-gating and respiratory navigator was performed in healthy volunteers with reconstruction performed using MPR and volume rendering. The extent of metabolic defect (MD) using PET/MRI and PET/CT was compared in patients and coronary territories (LAD, CX, RCA). Assessability of coronary lumen was judged as good, sub-optimal or non-assessable using a 16-segments coronary model.Results: Metabolic assessment was successful in all patients with MD being 19.2% vs 18.3% using PET/MRI and PET/CT, respectively (P=ns). The MD was 10.2%, 6 %, and 3 % vs 9.3%, 6 % and 3 % for LAD, CX and RCA territories, respectively (P= ns). Coronary angio-MRI was successful in all volunteers with 66 coronary segments visualised overall. The RCA was fully visualised in 4/5 volunteers and the left coronary arteries in 4/5 volunteers. Assessability in visualised segments was good, sub-optimal and non-assessable in 88 %, 2 % and 10 %, respectively.Conclusion: Hybrid PET/MRI devices may enable metabolic evaluation comparable to PET/CT with additional value owing to accurate functional and anatomical information including coronary assessment.

An integrated genomic and expression analysis of 7q deletion in splenic marginal zone lymphoma.

Splenic marginal zone lymphoma (SMZL) is an indolent B-cell lymphoproliferative disorder characterised by 7q32 deletion, but the target genes of this deletion remain unknown. In order to elucidate the genetic target of this deletion, we performed an integrative analysis of the genetic, epigenetic, transcriptomic and miRNomic data. High resolution array comparative genomic hybridization of 56 cases of SMZL delineated a minimally deleted region (2.8 Mb) at 7q32, but showed no evidence of any cryptic homozygous deletion or recurrent breakpoint in this region. Integrated transcriptomic analysis confirmed significant under-expression of a number of genes in this region in cases of SMZL with deletion, several of which showed hypermethylation. In addition, a cluster of 8 miRNA in this region showed under-expression in cases with the deletion, and three (miR-182/96/183) were also significantly under-expressed (P<0.05) in SMZL relative to other lymphomas. Genomic sequencing of these miRNA and IRF5, a strong candidate gene, did not show any evidence of somatic mutation in SMZL. These observations provide valuable guidance for further characterisation of 7q deletion.

Clinical features of myocardial infarction and myocarditis in young adults: a retrospective study.

OBJECTIVES: To evaluate the prevalence and clinical presentation of myocardial infarction (MI) and myocarditis in young adults presenting with chest pain (CP) and an elevated serum troponin I (TnI) to the emergency department (ED). DESIGN: Retrospective, observational, single-centre study. PARTICIPANTS: All consecutive patients 18-40 years old admitted to the ED for CP with an elevated TnI concentration. PRIMARY OUTCOME MEASURES: Prevalence of MI, myocarditis and the characterisation of clinical presentation. RESULTS: 1588 patients between 18 and 40 years old were admitted to the ED with CP during 30 consecutive months. 49 (3.1%) patients with an elevated TnI (>0.09 μg/l) were included. 32.7% (16/49) were diagnosed with MI (11 ST-elevation myocardial infarction (STEMI) and 5 non-ST-elevation myocardial infarction (NSTEMI)) and 59.2% (29/49) with myocarditis. Compared with patients with myocarditis, MI patients were older (34.1±3.8 vs 26.9±6.4, p=0.0002) with more cardiovascular risk factors (mean 2.06 vs 0.69). Diabetes (18.8% vs 0%, p=0.0039), dyslipidaemia (56.2% vs 3.4%, p<0.0001) and family history of coronary artery disease (CAD) (37.5% vs 10.3% p=0.050) were associated with MI. Fever or recent viral illness were present in 75.9% (22/29) of patients with myocarditis, and in 0% of MI patients (p<0.0001). During follow-up, two patients with myocarditis were re-admitted for CP. CONCLUSIONS: In this study, 32.7% of patients <40-year-old admitted to an ED with CP and elevated TnI had a diagnosis of MI. Key distinctive clinical factors include diabetes, dyslipidaemia, family history of CAD and fever or recent viral illness.

Total curvature and total torsion of knotted polymers

Previous work on radius of gyration and average crossing number has demonstrated that polymers with fixed topology show a different scaling behavior with respect to these characteristics than polymers with unrestricted topology. Using numerical simulations, we show here that the difference in the scaling behavior between polymers with restricted and unrestricted topology also applies to the total curvature and total torsion. For each knot type, the equilibrium length with respect to a given spatial characteristic is the number of edges at which the value of the characteristic is the same as the average for all polygons. This number appears to be correlated to physical properties of macromolecules, for example gel mobility as measured by the separation between distinct knot types. We also find that, on average, closed polymers require slightly more total curvature and slightly less total torsion than open polymers with the corresponding number of monomers.

Regulation of PIDD auto-proteolysis and activity by the molecular chaperone Hsp90.

In response to DNA damage, p53-induced protein with a death domain (PIDD) forms a complex called the PIDDosome, which either consists of PIDD, RIP-associated protein with a death domain and caspase-2, forming a platform for the activation of caspase-2, or contains PIDD, RIP1 and NEMO, important for NF-κB activation. PIDDosome activation is dependent on auto-processing of PIDD at two different sites, generating the fragments PIDD-C and PIDD-CC. Despite constitutive cleavage, endogenous PIDD remains inactive. In this study, we screened for novel PIDD regulators and identified heat shock protein 90 (Hsp90) as a major effector in both PIDD protein maturation and activation. Hsp90, together with p23, binds PIDD and inhibition of Hsp90 activity with geldanamycin efficiently disrupts this association and impairs PIDD auto-processing. Consequently, both PIDD-mediated NF-κB and caspase-2 activation are abrogated. Interestingly, PIDDosome formation itself is associated with Hsp90 release. Characterisation of cytoplasmic and nuclear pools of PIDD showed that active PIDD accumulates in the nucleus and that only cytoplasmic PIDD is bound to Hsp90. Finally, heat shock induces Hsp90 release from PIDD and PIDD nuclear translocation. Thus, Hsp90 has a major role in controlling PIDD functional activity.

Pharmacokinetic-pharmacodynamic profile of angiotensin II receptor antagonists.

The pharmacokinetic and pharmacodynamic properties of nonpeptide angiotensin antagonists in humans are reviewed in this paper. Representatives of this new therapeutic class share common features: lipophilia, intermediate bioavailability, high affinity for plasma proteins and liver metabolism; some have active metabolites. Angiotensin II antagonists block the blood pressure response to exogenous angiotensin II in healthy volunteers, decrease baseline blood pressure in both normal and hypertensive patients, produce a marked rise in plasma renin activity and endogenous angiotensin II and increase renal blood flow without altering glomerular filtration rate. These effects are dose-dependent, but their time course varies between the drugs owing to pharmacokinetic and pharmacodynamic differences. Additionally, the extent of blood pressure reduction is dependent on physiological factors such as sodium and water balance. The characterisation of their pharmacokinetic-pharmacodynamic relationships deserves further refinement for designing optimal therapeutic regimens and proposing dosage adaptations in specific conditions.