Quantification of BOLD fMRI parameters to infer cerebrovascular reactivity of the middle cerebral artery

PURPOSE

To quantify the amplitude and temporal aspects of the blood oxygenation level-dependent (BOLD) response to an auditory stimulus during normocapnia and hypercapnia in healthy subjects in order to establish which BOLD parameters are best suited to infer the cerebrovascular reactivity (CVR) in the middle cerebral artery (MCA) territory.

MATERIALS AND METHODS

Twenty healthy volunteers (mean age: 23.6 ± 3.7 years, 11 women) were subjected to a functional paradigm composed of five epochs of auditory stimulus (3 sec) intercalated by six intervals of rest (21 sec). Two levels of hypercapnia were achieved by a combination of air and CO2 while the end-tidal CO2 (ETCO2 ) was continually measured. An autoregressive method was applied to analyze four parameters of the BOLD signal: onset-time, time-to-peak, full-width-at-half-maximum (FWHM), and amplitude.

RESULTS

BOLD onset time (P < 0.001) and full-width at half-maximum (FWHM) (P < 0.05) increased linearly, while BOLD amplitude decreased (P < 0.001) linearly with increasing levels of hypercapnia. Test-retest for reproducibility in five subjects revealed excellent concordance for onset time and amplitude.

CONCLUSION

The robust linear dependence of BOLD onset time, FWHM, and amplitude to hypercapnia suggest future application of this protocol in clinical studies aimed at evaluating CVR of the MCA territory.

Biodistribution of lipid nanoparticles: a comparative study of pulmonary versus intravenous administration in rats

The advent of nanomedicine and increase knowledge on cellular and molecular biology has opened new opportunities on the clinical field. Selective drug targeting and protection of healthy tissues rules the rising interest that is being devoted to drug delivery system strategies, considering that the accurate choice of the carrier molecule will determine the pharmacokinetics and pharmacodynamics of drugs, yielding higher therapeutic efficacy. Despite the improvements in surgery and immunological approaches, tumor staging and cancer therapy remains a challenge, typically because they are ineffective in advanced stages of the disease, but also due to the conventional administration route (intravenous), and consequently the non-specificity of the potentially toxic drugs. The issue currently under the spotlight in drug targeting is the concept of drug delivery systems (DDS) and the impact that is inherent to their selectivity. Moreover, these particulate systems bring forth the possibility of using alternative routes to the conventional intravenous administration. This article reviews the applications of gamma-scintigraphic image technique to evaluate the advances and research on DDS engineering to the pulmonary administration, and the dependency of lung particle removal mechanism on both the administration route and the particulate system characteristic, based on literature data, as well as through the experimental studies performed in our group.

Cross-sectional and longitudinal associations between serum uric acid and metabolic syndrome

Research on the importance of serum uric acid (SUA) as a contributing metabolic factor to cardiovascular diseases has conducted to conflicting results, with most studies assuming a cross-sectional design. The aim of this study was to evaluate the association of SUA and metabolic syndrome (MetS) and its features. A representative sample of 2,485 individuals aged ≥18 years was randomly selected from the non-institutionalized resident population of Porto, Portugal. A total of 1,054 eligible subjects were included for the longitudinal analyses. Hyperuricemia was defined as SUA ≥70 mg/L in men and ≥60 mg/L in women. MetS was defined according the Joint Interim (2009) criteria. Associations were estimated using Poison regression and binomial models. In the cross-sectional analysis, subjects with hyperuricemia had a 2.10-fold increased risk of MetS as compared with normouricemic subjects (PR = 2.10, 95% CI: 1.68-2.63). Among MetS features, high triglycerides presented the strongest association with hyperuricemia (PR = 2.32, 95% CI: 1.84-2.91). The MetS crude incidence rate was 4.5/100 person-year (95% CI: 3.9-5.2) in normal uricemic and 13.0/100 person-year (95% CI: 8.5-20.0) in hyperuricemic participants. Using a multivariate longitudinal approach, hyperuricemia was positively associated with MetS incidence rate ratios (IRR = 1.73, 95% CI: 1.08-2.76). One standard deviation increase of SUA concentration was associated with a 1.22-fold increase in MetS risk (IRR = 1.22, 95% CI: 1.05-1.42). Elevated SUA presented the strongest association with high-triglycerides concentration (IRR = 1.44, 95%: 1.22-1.71) and waist circumference (IRR = 1.25, 95%: 1.05-1.49). The independent positive association between SUA and MetS suggested by this longitudinal study supports that SUA might be a risk factor for MetS.

Thermolabile liposomes: a controlled release delivery tool in diagnosis/therapy in experimental pulmonary ɶdema

Liposomes, usually assembled from organic/synthetic lipidic compounds, are biocompatible, biodegradable, non-toxic, and do not induce immune response. Due to their structural versatility in terms of size, composition, surface charge, bilayer fluidity and ability to encapsulate drugs regardless of their solubility, liposomes enable the production of a vast number and type of formulations with potential clinical use. They can be administered through several routes of administration (e.g. i.v., i.m., oral, nasal, etc.). The use of liposomes enables the variation and control retention of drugs in biologic fluids, enhancing blood circulation and specific compartments residence. They can be tailored to target specific tissues and cells. They can play a very important role for imaging diagnosis and/or therapy. After an extensive literature review of the subject, we selected a particular area of potential clinical application: pulmonary ɶdema. This clinical entity has a variety of possible etiologies, conducing to two main types of edema: cardiogenic and non-cardiogenic. At the moment a dedicated technique for the early diagnosis/therapy of this pathology is lacking. We propose a new methodology using a specially designed GUV formulation, encapsulating chosen radiotracers labeled with 99mTc. The aim of the work has been successfully achieved in an experimental animal model of cardiogenic pulmonary oedema. Experiments using an animal model of non-cardiogenic pulmonary oedema are in course (simultaneous study with two different drugs), using the same GUV methodology. Preliminary results are very promising.

Release of NO from a nitrosyl ruthenium complex through oxidation of mitochondrial NADH and effects on mitochondria

Nitrosyl ruthenium complexes are promising NO donor agents with numerous advantages for the biologic applications of NO. We have characterized the NO release from the nitrosyl ruthenium complex [Ru(NO(2))(bpy)(2)(4-pic)](+) (I) and the reactive oxygen/nitrogen species (ROS/RNS)-mediated NO actions on isolated rat liver mitochondria. The results indicated that oxidation of mitochondrial NADH promotes NO release from (I) in a manner mediated by NO(2) formation (at neutral pH) as in mammalian cells, followed by an oxygen atom transfer mechanism (OAT). The NO released from (I) uncoupled mitochondria at low concentrations/incubation times and inhibited the respiratory chain at high concentrations/incubation times. In the presence of ROS generated by mitochondria NO gave rise to peroxynitrite, which, in turn, inhibited the respiratory chain and oxidized membrane protein-thiols to elicit a Ca(2+)-independent mitochondrial permeability transition; this process was only partially inhibited by cyclosporine-A, almost fully inhibited by the thiol reagent N-ethylmaleimide (NEM) and fully inhibited by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO). These actions correlated with the release of cytochrome c from isolated mitochondria as detected by Western blotting analysis. These events, typically involved in cell necrosis and/or apoptosis denote a potential specific action of (I) and analogs against tumor cells via mitochondria-mediated processes.

Acquired hepatocerebral degeneration and hepatic encephalopathy: correlations and variety of clinical presentations in overt and subclinical liver disease

Acquired hepatocerebral degeneration (AHD) and hepatolenticular degeneration can have similar clinical presentations, but when a chronic liver disease and atypical motor findings coexist, the distinction between AHD and hepatic encephalopathy (HE) can be even more complicated. We describe three cases of AHD (two having HE) with different neuroimaging findings, distinct hepatic diseases and similar motor presentations, all presenting chronic arterial hypertension and weight loss before the disease manifestations. The diagnosis and physiopathology are commented upon and compared with previous reports. In conclusion, there are many correlations among HE, hepatolenticular degeneration and AHD, but the overlapping of AHD and HE could be more common depending on the clinical knowledge and diagnostic criteria adopted for each condition. Since AHD is not considered a priority that affects the liver transplant list, the prognosis in AHD patients remains poor, and flow interruption in portosystemic shunts must always be taken into account.

Carvedilol protects against apoptotic cell death induced by cisplatin in renal tubular epithelial cells

Cisplatin is a highly effective chemotherapeutic drug; however, its use is limited by nephrotoxicity. Studies showed that the renal injury produced by cisplatin involves oxidative stress and cell death mediated by apoptosis and necrosis in proximal tubular cells. The use of antioxidants to decrease cisplatin-induced renal cell death was suggested as a potential therapeutic measure. In this study the possible protective effects of carvedilol, a beta blocker with antioxidant activity, was examined against cisplatin-induced apoptosis in HK-2 human kidney proximal tubular cells. The mitochondrial events involved in this protection were also investigated. Four groups were used: controls (C), cisplatin alone at 25 μM (CIS), cisplatin 25 μM plus carvedilol 50 μM (CV + CIS), and carvedilol alone 50 μM (CV). Cell viability, apoptosis, caspase-9, and caspase-3 were determined. Data demonstrated that carvedilol effectively increased cell viability and minimized caspase activation and apoptosis in HK-2 cells, indicating this may be a promising drug to reduce nephrotoxicity induced by cisplatin.

Prevalence of new-onset insomnia in patients with obstructive sleep apnoea syndrome treated with nocturnal ventilatory support

INTRODUCTION

New-onset insomnia (NOI) associated with nocturnal ventilatory support (NVS) is becoming a reality in clinical practice; however there is a lack of data about its prevalence. Our aim was to determine the prevalence of NOI in patients with obstructive sleep apnoea syndrome (OSAS) under NVS and its associated risk factors.

MATERIAL AND METHODS

Descriptive cross-sectional study of 80 patients with OSAS under NVS. We compared two groups, with and without NOI, considering demographic characteristics, disease features, and personality. Patients under anxiolytic and/or antidepressant medication, with a weight loss of 10% or greater, and with restless legs symptoms were excluded.

RESULTS

Median age of patients was 60.0 (interquartile range (IQR) 10.0) years; 82.5% were male. Median initial Epworth Sleepiness Scale (ESS) and apnoea-hypopnoea index (AHI) were 12.5 (IQR 9.0) and 44.1 (IQR 22.4)/hr, respectively. The majority of patients (91.3%) were under auto-adjusting positive airway pressure (APAP). Insomnia at baseline was present in 30% of patients (n=24). Prevalence of NOI was 21.4% (12/56). Initial and/or intermediate insomnia were the most frequent subtypes (n=11). We found a statistically significant negative relation between NOI and pressure on 90% night-time (P(90)) (p=0.040).

CONCLUSIONS

OSAS patients under NVS presented a high prevalence of NOI. Patients with NOI presented lower levels of pressure using NVS, compared to the others.

Characterization of the stimulus for reactive oxygen species generation in calcium-overloaded mitochondria

We have used two different probes with distinct detection properties, dichlorodihydrofluorescein diacetate and Amplex Red/horseradish peroxidase, as well as different respiratory substrates and electron transport chain inhibitors, to characterize the reactive oxygen species (ROS) generation by the respiratory chain in calcium-overloaded mitochondria. Regardless of the respiratory substrate, calcium stimulated the mitochondrial generation of ROS, which were released at both the mitochondrial-matrix side and the extra-mitochondrial space, in a way insensitive to the mitochondrial permeability transition pores inhibitor cyclosporine A. In glutamate/malate-energized mitochondria, inhibition at complex I or complex III (ubiquinone cycle) similarly modulated ROS generation at either mitochondrial-matrix side or extra-mitochondrial space; this also occurred when the backflow of electrons to complex I in succinate-energized mitochondria was inhibited. On the other hand, in succinate-energized mitochondria the modulation of ROS generation at mitochondrial-matrix side or extra-mitochondrial space depends on the site of complex III which was inhibited. These results allow a straight comparison between the effects of different respiratory substrates and electron transport chain inhibitors on ROS generation at either mitochondrial-matrix side or extra-mitochondrial space in calcium-overloaded mitochondria.

Assessment of body fat composition disturbances by bioimpedance analysis in HIV-infected adults

HIV-lipodystrophy syndrome is characterized by different patterns of body fat distribution (BFD) which are identified by clinical and body composition (BC) assessment, including bioimpedance analysis (BIA). Our aim was to compare BC in HIV-infected patients on combination antiretroviral therapy (cART) according to 4 distinct phenotypes of BFD (G1-no lipodystrophy, G2-isolated central fat accumulation, G3-lipoatrophy, G4-mixed forms of lipodystrophy) and assessed factors associated with them. Anthropometry and BIA were performed in 344 HIV-1 patients. G2 and G4 phenotype patients had significantly higher fat mass (FM) but no differences were observed in fat-free mass (FFM) and total body water among the 4 phenotypes. Significant negative associations were found between the presence of lipoatrophy and female gender, body mass index (BMI), waist (WC), hip (HC) and thigh circumferences, and total body FM estimated by BIA. After adjustment for gender, cART duration and BMI, G3 had significant lower WC [odds ratio (OR)=0.84; 0.78- 0.90] and HC (OR=0.88; 0.81-0.96) mean. Independently of gender, cART duration and BMI, G2 remained significantly associated with higher WC (OR=1.11; 1.05-1.18) and HC (OR=1.15; 1.07-1.23) mean, and with FM estimated by BIA [FM as %, OR=1.17 (1.09-1.26); and FM as kg, OR=1.15 (1.06- 1.25)]. There was a significant positive association between G4 and female gender (OR=1.66; 1.01-2.75), BMI (OR=1.10; 1.04-1.17) and WC (OR=1.15; 1.09-1.21). The similar FFM along the BFD spectrum describes the actual BC of these patients without sarcopenia. In a clinical setting, BIA is an easy and useful tool to evaluate fat mass and FFM and gives us a picture of BC that was not possible with anthropometry.

Seeing with the eyes shut: neural basis of enhanced imagery following Ayahuasca ingestion

The hallucinogenic brew Ayahuasca, a rich source of serotonergic agonists and reuptake inhibitors, has been used for ages by Amazonian populations during religious ceremonies. Among all perceptual changes induced by Ayahuasca, the most remarkable are vivid "seeings." During such seeings, users report potent imagery. Using functional magnetic resonance imaging during a closed-eyes imagery task, we found that Ayahuasca produces a robust increase in the activation of several occipital, temporal, and frontal areas. In the primary visual area, the effect was comparable in magnitude to the activation levels of natural image with the eyes open. Importantly, this effect was specifically correlated with the occurrence of individual perceptual changes measured by psychiatric scales. The activity of cortical areas BA30 and BA37, known to be involved with episodic memory and the processing of contextual associations, was also potentiated by Ayahuasca intake during imagery. Finally, we detected a positive modulation by Ayahuasca of BA 10, a frontal area involved with intentional prospective imagination, working memory and the processing of information from internal sources. Therefore, our results indicate that Ayahuasca seeings stem from the activation of an extensive network generally involved with vision, memory, and intention. By boosting the intensity of recalled images to the same level of natural image, Ayahuasca lends a status of reality to inner experiences. It is therefore understandable why Ayahuasca was culturally selected over many centuries by rain forest shamans to facilitate mystical revelations of visual nature.

Extratemporal damage in temporal lobe epilepsy: magnetization transfer adds information to volumetric MR imaging

BACKGROUND AND PURPOSE

MTS is characterized by gliosis and atrophy of the hippocampus and related limbic structures. However, the damage is not limited to those structures with atrophy and has been reported in extratemporal regions. Because volumetric studies are nonspecific, the pathophysiology of the brain damage remains to be solved. MTI is an MR imaging technique more sensitive to subtle neuropathologic changes than conventional MR imaging. Here we combined MTI with VBM analysis to evaluate extratemporal damage in patients with TLE.

MATERIALS AND METHODS

We studied 23 healthy controls and 21 patients with TLE with mean ages, respectively, of 37.6 ± 10.9 and 38.6 ± 9.02 years. All subjects had a full clinical follow-up and MR imaging. We processed the images with VBM for volumetric analysis of WM and GM, as well as with voxel-based analysis of MTR for macromolecular integrity analysis.

RESULTS

In addition to MTR decrease in the temporal lobes, we found a significant decrease in GM and WM volumes. In the WM, the MTR decrease was correlated to volume loss detected by VBM, indicating that brain atrophy may explain part of the MTR decrease. We also found areas in which the MTR decrease was not associated with volume loss, suggesting an additional pathophysiologic process other than neuronal loss and atrophy underlying the MTR changes.

CONCLUSIONS

Our results support the hypothesis that there are widespread lesions in the brain, including the corpus callosum and the frontal lobe, affecting both GM and WM.

Utility of Ictal Single Photon Emission Computed Tomography in Mesial Temporal Lobe Epilepsy With Hippocampal Atrophy

BACKGROUND:

The development of newer diagnostic technologies has reduced the need for invasive electroencephalographic (EEG) studies in identifying the epileptogenic zone, especially in adult patients with mesial temporal lobe epilepsy and hippocampal sclerosis (MTLE-HS).

OBJECTIVE:

To evaluate ictal single photon emission computed tomography (SPECT) in the evaluation and treatment of patients with MTLE-HS.

METHODS:

MTLE patients were randomly assigned to those with (SPECT, n = 124) and without ictal SPECT (non-SPECT, n = 116) in an intent-to-treat protocol. Primary end points were the proportion of patients with invasive EEG studies, and those offered surgery. Secondary end points were the length of hospital stay and the proportion of patients with secondarily generalized seizures (SGS) during video-EEG, postsurgical seizure outcome, and hospital cost.

RESULTS:

The proportion of patients offered surgery was similar in the SPECT (85%) and non-SPECT groups (81%), as well as the proportion that had invasive EEG studies (27% vs 23%). The mean duration of hospital stay was 1 day longer for the SPECT group (P &lt; 0.001). SGS occurred in 51% of the SPECT and 26% of the non-SPECT group (P &lt; 0.001). The cost of the presurgical evaluation was 35% higher for the SPECT compared with the non-SPECT group (P &lt; 0.001). The proportion of patients seizure-free after surgery was similar in the SPECT (59%) compared with non-SPECT group (54%).

CONCLUSION:

Ictal-SPECT did not add localizing value beyond what was provided by EEG-video telemetry and structural MRI that altered the surgical decision and outcome for MTLE-HS patients. Ictal-SPECT increased hospital stay was associated with increased costs and a higher chance of SGS during video-EEG monitoring. These findings support the notion that a protocol including ictal SPECT is equivalent to one without SPECT in the presurgical evaluation of adult patients with MTLE-HS.

A comparison between magnetic resonance angiography at 3 Teslas (time-of-flight and contrast-enhanced) and flat-panel digital subtraction angiography in the assessment of embolized brain aneurysms

PURPOSE

To compare the time-of-flight and contrast-enhanced- magnetic resonance angiography techniques in a 3 Tesla magnetic resonance unit with digital subtraction angiography with the latest flat-panel technology and 3D reconstruction in the evaluation of embolized cerebral aneurysms.

INTRODUCTION

Many embolized aneurysms are subject to a recurrence of intra-aneurismal filling. Traditionally, imaging surveillance of coiled aneurysms has consisted of repeated digital subtraction angiography. However, this method has a small but significant risk of neurological complications, and many authors have advocated the use of noninvasive imaging methods for the surveillance of embolized aneurysms.

METHODS

Forty-three aneurysms in 30 patients were studied consecutively between November 2009 and May 2010. Two interventional neuroradiologists rated the time-of-flight-magnetic resonance angiography, the contrast-enhanced-magnetic resonance angiography, and finally the digital subtraction angiography, first independently and then in consensus. The status of aneurysm occlusion was assessed according to the Raymond scale, which indicates the level of recanalization according to degrees: Class 1: excluded aneurysm; Class 2: persistence of a residual neck; Class 3: persistence of a residual aneurysm. The agreement among the analyses was assessed by applying the Kappa statistic.

RESULTS

Inter-observer agreement was excellent for both methods (K = 0.93; 95 % CI: 0.84-1). Inter-technical agreement was almost perfect between time-of-flight-magnetic resonance angiography and digital subtraction angiography (K = 0.98; 95 % CI: 0.93-1) and between time-of-flight-magnetic resonance angiography and contrast-enhanced-magnetic resonance angiography (K = 0.98; 95% CI: 0.93-1). Disagreement occurred in only one case (2.3%), which was classified as Class I by time-of-flight-magnetic resonance angiography and Class II by digital subtraction angiography. The agreement between contrast-enhanced-magnetic resonance angiography and digital subtraction angiography was perfect (K = 1; 95% CI: 1-1). In three patients, in-stent stenosis was identified by magnetic resonance angiography but not confirmed by digital subtraction angiography.

CONCLUSION

Digital subtraction angiography and both 3T magnetic resonance angiography techniques have excellent reproducibility for the assessment of aneurysms embolized exclusively with coils. In those cases also treated with stent remodeling, digital subtraction angiography may still be necessary to confirm eventual parent artery stenosis, as identified by magnetic resonance angiography.

Anti-Leishmania titers and positive skin tests in patients cured of kala-azar

Visceral leishmaniasis (VL), also known as kala-azar, is an important public health problem. If not treated, virtually all clinically symptomatic patients die within months. The diagnosis is based on the Montenegro skin test (MST) and anti-Leishmania titers. Nevertheless, the time required for cured individuals living in a leishmaniasis-endemic area to present a positive skin test and negative anti-Leishmania serology is known. To determine the cellular and humoral immune response profile in relation to different times post-VL cure, a cross-sectional study was conducted on subjects from a kala-azar endemic area in Paço do Lumiar, MA, Brazil, on the basis of 1995-2005 notifications reported by the National Health Foundation/Regional Coordination of Maranhão. We visited cured individuals with a history of VL within the last 10 years. Seventy-four subjects (30 females) ranging in age from 1 to 44 years were included, all of them symptom free at the time of the study. A cellular immune response was observed in 73 (98.6%) subjects, whereas no significant antibody titers were detected by indirect immunofluorescence (IIF) in the sera of 69 (93.2%) cases. Ten years post-cure, 39 (52%) subjects had a positive MST and negative IIF reaction, while in one subject the skin and anti-Leishmania serology tests were negative. Two other subjects were positive in both tests 1 year after cure. These data suggest that a cellular immune response may still be present in subjects cured of VL regardless of post-cure time, and that the parasite persists in the host after clinical cure of the disease. This would explain the persistence of significant Leishmania sp antibody titers in some subjects after treatment.

Endovascular therapy for selected (most non-surgical) intracranial aneurysms in a Brazilian University Hospital

OBJECTIVE: The objective of this study was to evaluate technical, clinical and angiographic results of a nonsurgical series of intracranial aneurysms treated by endovascular approach at Hospital das Clínicas of Medical School of Ribeirão Preto - University of São Paulo. METHOD: Between August 2005 and November 2008, 137 aneurysms in 106 patients were endovascularly treated. Of these, 101 were unruptured in 75 patients and 36 aneurysms in 31 patients were treated during the acute phase. The data were prospectively studied. RESULTS: Sixty three aneurysms (46%) were treated with coils alone, 52 (38%) with balloon remodeling, 15 (10.9%) with stent remodeling, and 7 (5.1%) with therapeutic occlusion of the internal carotid artery. Six clinical complications (5.7%) were related to the procedures, 3 (2.8%) transitory and 3 (2.8%) permanent. Angiographic follow-up was available for 97 aneurysms (70.8%), clinical monitoring for 77 patients (72.6%) and telephone contact for 97 (91.5%). CONCLUSION: The technical, clinical and angiographic results found in this study are similar to those reported in the literature

The stability of the blood oxygenation level-dependent functional MRI response to motor tasks is altered in patients with chronic ischemic stroke

BACKGROUND AND PURPOSE

Functional MRI is a powerful tool to investigate recovery of brain function in patients with stroke. An inherent assumption in functional MRI data analysis is that the blood oxygenation level-dependent (BOLD) signal is stable over the course of the examination. In this study, we evaluated the validity of such assumption in patients with chronic stroke.

METHODS

Fifteen patients performed a simple motor task with repeated epochs using the paretic and the unaffected hand in separate runs. The corresponding BOLD signal time courses were extracted from the primary and supplementary motor areas of both hemispheres. Statistical maps were obtained by the conventional General Linear Model and by a parametric General Linear Model.

RESULTS

Stable BOLD amplitude was observed when the task was executed with the unaffected hand. Conversely, the BOLD signal amplitude in both primary and supplementary motor areas was progressively attenuated in every patient when the task was executed with the paretic hand. The conventional General Linear Model analysis failed to detect brain activation during movement of the paretic hand. However, the proposed parametric General Linear Model corrected the misdetection problem and showed robust activation in both primary and supplementary motor areas.

CONCLUSIONS

The use of data analysis tools that are built on the premise of a stable BOLD signal may lead to misdetection of functional regions and underestimation of brain activity in patients with stroke. The present data urge the use of caution when relying on the BOLD response as a marker of brain reorganization in patients with stroke.

Studies on the biodistribution of dextrin nanoparticles

The characterization of biodistribution is a central requirement in the development of biomedical applications based on the use of nanoparticles, in particular for controlled drug delivery. The blood circulation time, organ biodistribution and rate of excretion must be well characterized in the process of product development. In this work, the biodistribution of recently developed self-assembled dextrin nanoparticles is addressed. Functionalization of the dextrin nanoparticles with a DOTA-monoamide-type metal chelator, via click chemistry, is described. The metal chelator functionalized nanoparticles were labelled with a gamma-emitting (153)Sm(3+) radioisotope and the blood clearance rate and organ biodistribution of the nanoparticles were obtained. The effect of PEG surface coating on the blood clearance rate and organ biodistribution of the nanoparticles was also studied.

Impact of adenosine nucleotide translocase (ANT) proline isomerization on Ca2+-induced cysteine relative mobility/mitochondrial permeability transition pore

Mitochondrial membrane carriers containing proline and cysteine, such as adenine nucleotide translocase (ANT), are potential targets of cyclophilin D (CyP-D) and potential Ca(2+)-induced permeability transition pore (PTP) components or regulators; CyP-D, a mitochondrial peptidyl-prolyl cis-trans isomerase, is the probable target of the PTP inhibitor cyclosporine A (CsA). In the present study, the impact of proline isomerization (from trans to cis) on the mitochondrial membrane carriers containing proline and cysteine was addressed using ANT as model. For this purpose, two different approaches were used: (i) Molecular dynamic (MD) analysis of ANT-Cys(56) relative mobility and (ii) light scattering techniques employing rat liver isolated mitochondria to assess both Ca(2+)-induced ANT conformational change and mitochondrial swelling. ANT-Pro(61) isomerization increased ANT-Cys(56) relative mobility and, moreover, desensitized ANT to the prevention of this effect by ADP. In addition, Ca(2+) induced ANT "c" conformation and opened PTP; while the first effect was fully inhibited, the second was only attenuated by CsA or ADP. Atractyloside (ATR), in turn, stabilized Ca(2+)-induced ANT "c" conformation, rendering the ANT conformational change and PTP opening less sensitive to the inhibition by CsA or ADP. These results suggest that Ca(2+) induces the ANT "c" conformation, apparently associated with PTP opening, but requires the CyP-D peptidyl-prolyl cis-trans isomerase activity for sustaining both effects.

(1)H magnetic resonance spectroscopy imaging of the hippocampus in patients with panic disorder

Recent theories of panic disorder propose an extensive involvement of limbic system structures, such as the hippocampus, in the pathophysiology of this condition. Despite this, no prior study has examined exclusively the hippocampal neurochemistry in this disorder. The current study used proton magnetic resonance spectroscopy imaging ((1)H-MRSI) to examine possible abnormalities in the hippocampus in panic disorder patients. Participants comprised 25 panic patients and 18 psychiatrically healthy controls. N-acetylaspartate (NAA, a putative marker of neuronal viability) and choline (Cho, involved in the synthesis and degradation of cell membranes) levels were quantified relative to creatine (Cr, which is thought to be relatively stable among individuals and in different metabolic condition) in both right and left hippocampi. Compared with controls, panic patients demonstrated significantly lower NAA/Cr in the left hippocampus. No other difference was detected. This result is consistent with previous neuroimaging findings of hippocampal alterations in panic and provides the first neurochemical evidence suggestive of involvement of this structure in the disorder. Moreover, lower left hippocampal NAA/Cr in panic disorder may possibly reflect neuronal loss and/or neuronal metabolic dysfunction, and could be related to a deficit in evaluating ambiguous cues.

Poly(dimethyl siloxane) surface modification by low pressure plasma to improve its characteristics towards biomedical applications

Poly(dimethyl siloxane) elastomer, (PDMS) is widely used as a biomaterial. However, PDMS is very hydrophobic and easily colonized by several bacteria and yeasts. Consequently, surface modification has been used to improve its wettability and reduce bacterial adhesion. The aim of this work was to modify the PDMS surface in order to improve its hydrophilicity and bacterial cell repulsion to be used as a biomaterial. Plasma was used to activate the PDMS surface and sequentially promote the attachment of a synthetic surfactant, Pluronic F-68, or a polymer, Poly(ethylene glycol) methyl methacrylate, PEGMA. Bare PDMS, PDMS argon plasma activated, PDMS coated with Pluronic F-68 and PEGMA-grafted PDMS were characterized by contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The influence of the surface modifications on blood compatibility of the materials was evaluated by thrombosis and haemolysis assays. The cytotoxicity of these materials was tested for mouse macrophages. After modification, AFM results suggest the presence of a distinct layer at the surface and by the contact angle measures it was observed an increase of hydrophilicity. XPS analysis indicates an increase of the oxygen content at the surface as a result of the modification. All the studied materials revealed no toxicity and were found to be non-haemolytic or in some cases slightly haemolytic. Therefore, plasma was found to be an effective technique for the PDMS surface modification.

Low-molecular-mass peptides from the venom of the Amazonian viper Bothrops atrox protect against brain mitochondrial swelling in rat: potential for neuroprotection

The neurodegenerative diseases are important causes of morbidity and mortality in Western countries. Common mechanisms of toxicity involving mitochondrial damage have been suggested; however, a definitive treatment has not yet been found. Therefore, there has been great interest in the development of mitochondria-targeted protective compounds for the treatment of neuropathies. Animal toxins represent a promising source of new molecules with neuroprotective activity and potential to originate new drugs. We present here the effects of a low-molecular-mass peptides fraction (Ba-V) from Bothrops atrox snake venom, on rat brain mitochondrial function. Ba-V did not induce the mitochondrial swelling and moreover, was as effective as cyclosporin A (CsA) to inhibit the calcium/phosphate-induced swelling, which indicates its potential to prevent the mitochondrial permeability transition (MPT). The membrane electrochemical potential, the oxygen consumption during states-3 and -4 respirations as well as the respiratory control ratio (RCR) were not affected by Ba-V. Additionally, Ba-V did not induce reactive oxygen species (ROS) generation. Interestingly, Ba-V did not protect against the generation of ROS induced by t-BOH, which suggests a protection mechanism other than ROS scavenging. Given the important role of the mitochondrial damage and, more specifically, of MPT, in the development of neuropathies, Ba-V might be useful in the future strategies for the treatment of these diseases.

1,5-Bis(2,5-dimethyl-1H-pyrrol-1-yl)naphthalene

In the title compound, C₂₂H₂₂N₂, the asymmetric unit contains one half-mol­ecule. A crystallographic inversion centre is located at the mid-point of the bond common to both rings, in the central naphthalene unit. Quantum-mechanical ab initio calculations on the isolated mol­ecule showed that the minimum energy configuration occurs when the naphthalene ring system and the pyrrolyl groups deviate only slightly from perpendicularity. In the crystal, due to the effects of crystal packing, the mol­ecule deviates by approximately 4° from the a priori expected ideal value of 90° [C—C—N—C torsion angle = 86.11 (15)°].

Carvedilol protects against the renal mitochondrial toxicity induced by cisplatin in rats

The clinical use of cisplatin is highly limited by its nephrotoxicity, which has been associated with mitochondrial dysfunction. We investigated the protective effect of carvedilol, an antihypertensive with strong antioxidant properties, against the nephrotoxicity induced by cisplatin in rats. Carvedilol was able to counteract the renal damage by preventing the mitochondrial dysfunction induced by cisplatin. The mitochondrial eletrochemical potential, calcium uptake, respiration and the phosphorylative capacity were preserved by the co-administration of carvedilol. The mechanism of protection probably does not involve alterations in the cellular and sub-cellular distribution of cisplatin. The study suggests that carvedilol is a potential drug for the adjuvant nephroprotective therapy during cisplatin chemotherapy.