The blood brain barrier dysfunction in healthy aging and dementia: why, how, what for?

The blood brain barrier (BBB) is an indispensable structure that maintains the central nervous system (CNS) microenvironment for a correct neuronal function. It is composed by high specialized microvessels, surrounded by astrocytes, pericytes, neurons and microglia cells, which tightly control the influx and efflux of substances to the brain parenchyma. During aging, the BBB becomes impaired, and it may contribute to the development of neurodegenerative and neurological disorders including Alzheimer's disease and other dementias. Restoring BBB can be a strategy to prevent disease onset and development, reducing the symptoms of these conditions. This work critically reviews the major mechanisms underlying BBB breakdown in healthy and unhealthy aging, as well as biomarkers and methodologies that accurately assess its impairment. Complementarily, potential therapeutic targets are discussed as new strategies to restore the normal function of the BBB in aging.

Intranasal delivery of paroxetine: A preclinical study on pharmacokinetics, depressive-like behaviour, and neurochemical sex differences.

Treatment of major depressive disorder remains a major unmet clinical need. Given the advantages of intranasal administration for targeted brain delivery, the present study aimed at investigating the pharmacokinetics of paroxetine, after its intranasal instillation and assessing its potential therapeutic effect on female and male mice subjected to unpredictable chronic mild stress (UCMS) protocol. IN administration revealed direct nose-to-brain paroxetine delivery but dose- and sex-dependent differences. Pharmacokinetics was nonlinear and paroxetine concentrations were consistently higher in plasma and brain of male mice. Additionally, UCMS decreased animal preference for sucrose in both male and female mice following acute (p < 0.01) and chronic stress (p < 0.05), suggesting anhedonia. Both male and female mice exhibited depressive-like behavior in the forced swimming test. UCMS females displayed a significantly longer immobility time and shorter climbing time than the control group (p < 0.05), while no differences were found between male mice. Two weeks of paroxetine intranasal administration reduced immobility time and lengthened climbing and swimming time, approaching values similar to those observed in the healthy control group. The therapeutic effect was stronger on female mice. Importantly, melatonin plasma levels were significantly decreased in female mice following UCMS (p < 0.05), while males exhibited heightened corticosterone levels. On the other hand, treatment with IN paroxetine significantly increased corticosterone and melatonin levels in both sexes compared to healthy mice (p < 0.05). Intranasal paroxetine delivery undoubtedly ameliorated the behavioral despair, characteristic of depressive-like animals. Despite its efficiency in male and female mice subjected to UCMS, females were more prone to this novel therapeutic strategy.

Interaction of a Homologous Series of Amphiphiles with P-glycoprotein in a Membrane Environment-Contributions of Polar and Non-Polar Interactions.

The transport of drugs by efflux transporters in biomembranes limits their bioavailability and is a major determinant of drug resistance development by cancer cells and pathogens. A large number of chemically dissimilar drugs are transported, and despite extensive studies, the molecular determinants of substrate specificity are still not well understood. In this work, we explore the role of polar and non-polar interactions on the interaction of a homologous series of fluorescent amphiphiles with the efflux transporter P-glycoprotein. The interaction of the amphiphiles with P-glycoprotein is evaluated through effects on ATPase activity, efficiency in inhibition of [125I]-IAAP binding, and partition to the whole native membranes containing the transporter. The results were complemented with partition to model membranes with a representative lipid composition, and details on the interactions established were obtained from MD simulations. We show that when the total concentration of amphiphile is considered, the binding parameters obtained are apparent and do not reflect the affinity for P-gp. A new formalism is proposed that includes sequestration of the amphiphiles in the lipid bilayer and the possible binding of several molecules in P-gp's substrate-binding pocket. The intrinsic binding affinity thus obtained is essentially independent of amphiphile hydrophobicity, highlighting the importance of polar interactions. An increase in the lipophilicity and amphiphilicity led to a more efficient association with the lipid bilayer, which maintains the non-polar groups of the amphiphiles in the bilayer, while the polar groups interact with P-gp's binding pocket. The presence of several amphiphiles in this orientation is proposed as a mechanism for inhibition of P-pg function.

Adhesion modulates cell morphology and migration within dense fibrous networks.

One of the most fundamental abilities required for the sustainability of complex life forms is active cell migration, since it is essential in diverse processes from morphogenesis to leukocyte chemotaxis in immune response. The movement of a cell is the result of intricate mechanisms, that involve the coordination between mechanical forces, biochemical regulatory pathways and environmental cues. In particular, epithelial cancer cells have to employ mechanical strategies in order to migrate through the tissue's basement membrane and infiltrate the bloodstream during the invasion stage of metastasis. In this work we explore how mechanical interactions such as spatial restriction and adhesion affect migration of a self-propelled droplet in dense fibrous media. We have performed a systematic analysis using a phase-field model and we propose a novel approach to simulate cell migration with dissipative particle dynamics modelling. With this purpose we have measured in our simulation the cell's velocity and quantified its morphology as a function of the fibre density and of its adhesiveness to the matrix fibres. Furthermore, we have compared our results to a previous in vitro migration assay of fibrosarcoma cells in fibrous matrices. The results show good agreement between the two methodologies and experiments in the literature, which indicates that these minimalist descriptions are able to capture the main features of the system. Our results indicate that adhesiveness is critical for cell migration, by modulating cell morphology in crowded environments and by enhancing cell velocity. In addition, our analysis suggests that matrix metalloproteinases (MMPs) play an important role as adhesiveness modulators. We propose that new assays should be carried out to address the role of adhesion and the effect of different MMPs in cell migration under confined conditions.

Imaging probes for non-invasive tumoral detection and functional monitoring of cancer multidrug resistance.

Aim: Several cationic radiotracers originally developed as myocardial perfusion agents have shown potential for both early detection of cancer and non-invasive monitoring of multiple drug resistance (MDR) by single photon emission computed tomography. We have introduced two cationic complexes, 99mTc-DMEOP [di-methoxy-tris-pyrazolyl-99mTc-(CO)3] and 99mTc-TMEOP [tri-methoxy-tris-pyrazolyl-99mTc-(CO)3], which showed excellent preclinical results as cardiac imaging probes, namely a persistent heart uptake with rapid blood and liver clearance. This study aimed at the evaluation of their usefulness for tumoral detection and functional assessment of MDR. Methods: The uptake and efflux kinetics of 99mTc-DMEOP and 99mTc-TMEOP were evaluated in human prostate, lung, and breast cancer cell lines, including drug-resistant cell lines that are known to overexpress the MDR P-glycoprotein (Pgp). The effects of MDR modulators were also studied. In vivo studies were performed in xenografted tumor models, and the MDR phenotype of the tumors was confirmed by Western blot. Results: The uptake kinetics of both complexes in human cancer cell lines is comparable with the one found for 99mTc-Sestamibi, increasing over time. The uptake of 99mTc-TMEOP is greatly reduced in cells overexpressing Pgp and increased in the presence of a Pgp modulator. In nude mice, the tumor uptake of 99mTc-TMEOP was higher in the MCF-7 xenografts compared with the MCF7 Pgp tumors. Conclusion: The uptake kinetics of both complexes in human cancer cell lines is comparable with the one found for 99mTc-Sestamibi, increasing over time. The uptake of 99mTc-TMEOP is greatly reduced in cells overexpressing Pgp, and increased in the presence of a Pgp modulator. In nude mice, the tumor uptake of 99mTc-TMEOP was higher in the MCF-7 xenografts compared with the MCF7 Pgp tumors.

Early, real-world experience with direct oral anticoagulants in the treatment of intermediate-high risk acute pulmonary embolism.

INTRODUCTION: Intermediate-high risk pulmonary embolism (IHR-PE) has a poor prognosis, but is under-represented in trials of direct oral anticoagulants (DOACs) in venous thromboembolic disease (VTE). We aimed to assess whether the administration of DOACs was equivalent to the conventional (CONV) treatment of low-molecular weight heparin bridged with warfarin for treating IHR-PE. METHODS: We conducted a retrospective cohort study including 59 consecutive patients admitted with IHR-PE and followed for up to three months after discharge. Two groups were created based on the anticoagulant strategy: CONV (n=35) and DOAC (n=24). The efficacy endpoints were death, recurrent PE, estimated pulmonary artery systolic pressure (PASP), right ventricular systolic function (RVSF) at discharge, and length of stay; the safety endpoint was major bleeding. RESULTS: The two groups were similar regarding demographics, PE etiology and markers of clinical severity. There were four in-hospital deaths in the CONV group and none in the DOAC group. No recurrent PE or major bleeding event was recorded in either group. At discharge, neither PASP nor RVSF was different between the groups. Patients in the DOAC group were discharged 1.7 days earlier on average than patients in the CONV group (4.7±2.4 vs. 3.0±1.5 days, p=0.002). CONCLUSIONS: The adoption of a DOAC treatment strategy in this real-world cohort of IHR-PE patients was associated with similar efficacy and safety to the CONV approach. The fact that monitoring of anticoagulation effect was unnecessary probably led to the significant reduction in length of stay.

An atypical spondylodiscitis: case report / Uma espondilodiscite atípica: relato de caso

Spondylodiscitis is a rare pathology, however its incidence has been rising in recent years. Its signs and symptoms are nonspecific therefore the diagnosis may be delayed from 2 to 6 months. The main symptom is back or neck pain but some patients may experience no pain. The authors report the case of an 82 year old man with a presentation of initial cough, followed by monoarthritis, then polyarthritis and finally paraparesis, accompanied by fever and elevation of infection markers. The insidious evolution delayed the diagnosis of spondylodiscitis as well as its treatment. The identified pathogen was Streptococcus pneumoniae, a very rare cause of spondylodiscitis. After 6 weeks of antibiotics the patient was discharged. Spondylodiscitis diagnosis requires a high level of suspicion due to its wide range of clinical presentations and must be ruled out when we are faced with a fever of unknown origin or an inappropriate response to treatment.

A espondilodiscite é uma patologia rara, porém sua incidência tem vindo a aumentar nos últimos anos. Os seus sinais e sintomas não são específicos e, como tal, o diagnóstico pode ser atrasado de 2 a 6 meses. O principal sintoma é a dor nas costas ou no pescoço, mas alguns doentes podem não apresentar dor. Os autores relatam o caso de um homem de 82 anos, com uma apresentação inicial de tosse, seguida de monoartrite, depois poliartrite, e finalmente paraparésia, acompanhado de elevação dos parâmetros de infecção. A evolução insidiosa atrasou o diagnóstico de espondilodiscite, assim como o seu tratamento. O patogénio identificado foi Streptococcus pneumoniae, uma causa bastante rara de espondilodiscite. Após 6 semanas de anti-bioterapia o doente teve alta. A espondilodiscite é um diagnóstico que requer um alto nível de suspeição dada a ampla variedade de apresentações clínicas e deve ser excluída quando estamos perante um caso de febre de origem indeterminada ou uma resposta inadequada ao tratamento.

Progesterone receptor targeting with radiolabelled steroids: an approach in predicting breast cancer response to therapy.

Steroid receptors have demonstrated to be potentially useful biological targets for the diagnosis and therapy follow-up of hormonally responsive cancers. The over-expression of these proteins in human cancer cells as well as their binding characteristics provides a favourable mechanism for the localization of malignant tumours. The need for newer and more selective probes to non-invasively assess steroid receptor expression in hormone-responsive tumours has encouraged the synthesis and the biological evaluation of several steroidal derivatives labelled with positron and gamma emitters. The physiological effects of the steroid hormone progesterone are mediated by the progesterone receptor (PR). Since PR expression is stimulated by the oestrogen receptor (ER), PR status has been considered as a biomarker of ER activity and its value for predicting and monitoring therapeutic efficacy of hormonal therapy has been studied. Imaging of PR-expressing breast cancer patients under hormonal therapy may be advantageous, since the response to therapy can be more accurately predicted after quantification of both ER and PR status. Thus, ligands for PR targeting, although much less explored than ER ligands, have gained some importance lately as potential PET and SPECT tumour imaging agents. In this review, we present a brief survey of explored approaches for progesterone targeting using radiolabelled progestins as potential clinical probes to predict responsiveness to breast cancer therapy. This article is part of a Special Issue entitled "Synthesis and biological testing of steroid derivatives as inhibitors".

Synthesis, in silico, in vitro, and in vivo investigation of 5-[¹¹C]methoxy-substituted sunitinib, a tyrosine kinase inhibitor of VEGFR-2.

Sunitinib (SU11248) is a highly potent tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor (VEGFR). Radiolabeled inhibitors of receptor tyrosine kinases (RTKs) might be useful tools for monitoring RTKs levels in tumor tissue giving valuable information for anti-angiogenic therapy. Herein we report the synthesis of 5-methoxy-sunitinib 5 and its (11)C-radiolabeled analog [(11)C]-5. The non-radioactive reference compound 5 was prepared by Knoevenagel condensation of 5-methoxy-2-oxindole with the corresponding substituted 5-formyl-1H-pyrrole. A binding constant (K(d)) of 20 nM for 5 was determined by competition binding assay against VEGFR-2. In addition, the binding mode of sunitinib and its 5-methoxy substituted derivative was studied by flexible docking simulations. These studies revealed that the substitution of the fluorine at position 5 of the oxindole scaffold by a methoxy group did not affect the inhibitor orientation, but affected the electrostatic and van der Waals interactions of the ligand with residues near the DFG motif of VEGFR-2. 5-[(11)C]methoxy-sunitinib ([(11)C]-5) was synthesized by reaction of the desmethyl precursor with [(11)C]CH(3)I in the presence of DMF and NaOH in 17 ± 3% decay-corrected radiochemical yield at a specific activity of 162-205 GBq/µmol (EOS). In vivo stability studies of [(11)C]-5 in rat blood showed that more than 70% of the injected compound was in blood stream, 60 min after administration.

Rhenium and technetium tricarbonyl complexes anchored by pyrazole-based tripods: novel lead structures for the design of myocardial imaging agents.

This report describes the synthesis and biological evaluation of cationic (99m)Tc-tricarbonyl complexes anchored by ether-containing tris(pyrazolyl)methane or bis(pyrazolyl)ethanamine ligands to be applied in the design of radiopharmaceuticals for myocardial imaging: fac-[(99m)Tc(CO)(3){RC(pz)(3)}](+) (R = H (1a), MeOCH(2) (2a), EtOCH(2) (3a), (n)PrOCH(2) (4a)) and fac-[(99m)Tc(CO)(3){RNHCH(2)CH(pz)(2)}](+) (R = H (5a), MeO(CH(2))(2) (6a)) (pz = pyrazolyl). At the no carrier added level, complexes 1a-6a were obtained in high radiochemical yield (> 98%) by reaction of fac-[(99m)Tc(CO)(3)(H(2)O)(3)](+) with the corresponding tripod chelator in aqueous medium. All these complexes display a high in vitro and in vivo stability, except 6a which metabolizes in vivo yielding fac-[(99m)Tc(CO)(3){HO(CH(2))(2)NHCH(2)CH(pz)(2)}](+) (7a). Biological studies in mice have shown that among the radiotracers evaluated in this work, 3a, anchored by a tris(pyrazolyl)methane chelator bearing an ethyl methyl ether substituent, has the highest heart uptake (3.6 +/- 0.5%ID g(-1) at 60 min p.i.). Complex 3a presents also the best heart: blood, heart: liver and heart: lung ratios, appearing as the most promising as a potential myocardial imaging agent. The chemical identity of 1a-7a was ascertained by HPLC comparison with the previously reported fac-[Re(CO)(3){HC(pz)(3)}]Br (1) and with the novel fac-[Re(CO)(3){RC(pz)(3)}]Br (R = MeOCH(2) (2), EtOCH(2) (3), (n)PrOCH(2)(4)) and fac-[Re(CO)(3){RNHCH(2)CH(pz)(2)}]Br (R = H (5), MeO(CH(2))(2) (6) HO(CH(2))(2) (7)). The novel Re(I) tricarbonyl complexes, 2-7, were characterized by the common analytical techniques, including single crystal X-ray diffraction analysis. The solid state structure confirmed the presence of facial and tridentate (kappa(3)-N(3)) anchor ligands. Solution NMR studies have also shown that this kappa(3)-N(3) coordination mode is retained in solution for all complexes (2-7).