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1.
NMR Biomed ; 36(4): e4703, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-35075706

RESUMO

The aim of the current study was to establish a controlled and reproducible model to study metabolic changes during oxygen-glucose deprivation (OGD) in rat brain using a nuclear magnetic resonance (NMR)-compatible perfusion system. Rat brains were cut into 400-µm thick slices and perfused with artificial cerebrospinal fluid (aCSF) in a 10-mm NMR tube inside a 600-MHz NMR spectrometer. Four experimental conditions were tested: (1) continuous perfusion with aCSF with glucose and normoxia, and (2) 30-, (3) 60-, or (4) 120-min periods of OGD followed by reperfusion of aCSF containing glucose and normoxia. The energetic state of perfused brain slices was measured using phosphorus (31 P) NMR and metabolite changes were measured using proton (1 H) NMR. aCSF samples were collected every 30 min and analyzed using 1 H NMR. The sample temperature was maintained at 36.7 ± 0.1°C and was checked periodically throughout the experiments. Brain slice histology was compared before and after OGD in the perfusion system using hematoxylin-eosin-saffron staining. NMR data clearly distinguished three severity groups (mild, moderate, and severe) after 30, 60, and 120 min of OGD, respectively, compared with the control group. 31 P NMR spectra obtained from controls showed that phosphocreatine levels were stable for 5 h inside the perfusion system. Control 1 H NMR spectra showed that lactate, N-acetylaspartic acid, glutamate, γ-aminobutyric acid, and creatine metabolite levels were stable over time, with lactate levels having a tendency to gradually increase due to the recirculation of the aCSF in the perfusion system. A controlled and reproducible perfusion system was established to study the energetic and metabolic changes in rat brain slices during and after OGD of varying severity.


Assuntos
Oxigênio , Fósforo , Ratos , Animais , Oxigênio/metabolismo , Fósforo/metabolismo , Prótons , Glucose/metabolismo , Espectroscopia de Ressonância Magnética , Encéfalo/metabolismo , Perfusão , Ácido Láctico/metabolismo , Metabolômica
2.
Dev Neurosci ; 39(1-4): 36-48, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28448965

RESUMO

Perinatal hypoxic-ischemic brain injury is a major health problem. Adjuvant treatments that improve the neuroprotective effect of the current treatment, therapeutic hypothermia, are urgently needed. The growing knowledge about the complex pathophysiology of hypoxia-ischemia (HI) has led to the discovery of several important targets for neuroprotection. Early interventions should focus on the preservation of energy metabolism, the reduction of glutamate excitotoxicity and oxidative stress, the maintenance of calcium homeostasis, and the prevention of apoptosis. Delayed interventions should promote injury repair. The multiple metabolic changes following HI as well as the metabolic effects of potential treatments can be observed noninvasively by magnetic resonance spectroscopy (MRS). This mini-review provides an overview of the neuroprotective pharmacological agents that have been evaluated with 1H/31P/13C MRS. A better understanding of how these agents influence cerebral metabolism and the use of relevant translational MRS biomarkers can guide future clinical trials.


Assuntos
Hipóxia-Isquemia Encefálica/diagnóstico por imagem , Espectroscopia de Ressonância Magnética/métodos , Fármacos Neuroprotetores/uso terapêutico , Animais , Asfixia Neonatal/diagnóstico por imagem , Asfixia Neonatal/terapia , Encéfalo/efeitos dos fármacos , Humanos , Recém-Nascido
3.
Neurochem Res ; 42(1): 115-132, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28019006

RESUMO

Neonatal hypoxia-ischemia (HI) and the delayed injury cascade that follows involve excitotoxicity, oxidative stress and mitochondrial failure. The susceptibility to excitotoxicity of the neonatal brain may be related to the capacity of astrocytes for glutamate uptake. Furthermore, the neonatal brain is vulnerable to oxidative stress, and the pentose phosphate pathway (PPP) may be of particular importance for limiting this kind of injury. Also, in the neonatal brain, neurons depend upon de novo synthesis of neurotransmitters via pyruvate carboxylase in astrocytes to increase neurotransmitter pools during normal brain development. Several recent publications describing intermediary brain metabolism following neonatal HI have yielded interesting results: (1) Following HI there is a prolonged depression of mitochondrial metabolism in agreement with emerging evidence of mitochondria as vulnerable targets in the delayed injury cascade. (2) Astrocytes, like neurons, are metabolically impaired following HI, and the degree of astrocytic malfunction may be an indicator of the outcome following hypoxic and hypoxic-ischemic brain injury. (3) Glutamate transfer from neurons to astrocytes is not increased following neonatal HI, which may imply that astrocytes fail to upregulate glutamate uptake in response to the massive glutamate release during HI, thus contributing to excitotoxicity. (4) In the neonatal brain, the activity of the PPP is reduced following HI, which may add to the susceptibility of the neonatal brain to oxidative stress. The present review aims to discuss the metabolic temporal alterations observed in the neonatal brain following HI.


Assuntos
Astrócitos/metabolismo , Encéfalo/metabolismo , Glucose/metabolismo , Hipóxia-Isquemia Encefálica/metabolismo , Neurônios/metabolismo , Animais , Animais Recém-Nascidos , Humanos , Ratos
4.
J Neurochem ; 136(2): 339-50, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26526584

RESUMO

Mitochondrial impairment is a key feature underlying neonatal hypoxic-ischemic (HI) brain injury and melatonin is potentially neuroprotective through its effects on mitochondria. In this study, we have used (1) H and (13) C NMR spectroscopy after injection of [1-(13) C]glucose and [1,2-(13) C]acetate to examine neuronal and astrocytic metabolism in the early reperfusion phase after unilateral HI brain injury in 7-day-old rat pups, exploring the effects of HI on mitochondrial function and the potential protective effects of melatonin on brain metabolism. One hour after hypoxia-ischemia, astrocytic metabolism was recovered and glycolysis was normalized, whereas mitochondrial metabolism in neurons was clearly impaired. Pyruvate carboxylation was also lower in both hemispheres after HI. The transfer of glutamate from neurons to astrocytes was higher whereas the transfer of glutamine from astrocytes to neurons was lower 1 h after HI in the contralateral hemisphere. Neuronal metabolism was equally affected in pups treated with melatonin (10 mg/kg) immediately after HI as in vehicle treated pups indicating that the given dose of melatonin was not capable of protecting the neuronal mitochondria in this early phase after HI brain injury. However, any beneficial effects of melatonin might have been masked by modulatory effects of the solvent dimethyl sulfoxide on cerebral metabolism. Neuronal and astrocytic metabolism was examined by (13) C and (1) H NMR spectroscopy in the early reperfusion phase after unilateral hypoxic-ischemic brain injury and melatonin treatment in neonatal rats. One hour after hypoxia-ischemia astrocytic mitochondrial metabolism had recovered and glycolysis was normalized, whereas mitochondrial metabolism in neurons was impaired. Melatonin treatment did not show a protective effect on neuronal metabolism.


Assuntos
Antioxidantes/uso terapêutico , Lesões Encefálicas/etiologia , Lesões Encefálicas/terapia , Isquemia Encefálica/complicações , Melatonina/uso terapêutico , Reperfusão , Acetatos/metabolismo , Animais , Animais Recém-Nascidos , Astrócitos/metabolismo , Lesões Encefálicas/patologia , Modelos Animais de Doenças , Feminino , Lateralidade Funcional/efeitos dos fármacos , Glucose/metabolismo , Isótopos/metabolismo , Espectroscopia de Ressonância Magnética , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Neurônios/metabolismo , Gravidez , Piruvato Carboxilase/metabolismo , Ratos
5.
J Magn Reson Imaging ; 43(5): 1207-17, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26559017

RESUMO

PURPOSE: To improve early diagnosis of prostate cancer to aid clinical decision-making. Diffusion-weighted magnetic resonance imaging (DW-MRI) is sensitive to water diffusion throughout tissues, which correlates with Gleason score, a histological measure of prostate cancer aggressiveness. In this study the ability of DW-MRI to detect prostate cancer onset and development was evaluated in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice. MATERIALS AND METHODS: T2 -weighted and DW-MRI were acquired using a 7T MR scanner, 200 mm bore diameter; 10 TRAMP and 6 C57BL/6 control mice were scanned every 4 weeks from 8 weeks of age until sacrifice at 28-30 weeks. After sacrifice, the genitourinary tract was excised and sectioned for histological analysis. Histology slides registered with DW-MR images allowed for validation of DW-MR images and the apparent diffusion coefficient (ADC) as tools for cancer detection and disease stratification. An automated early assessment tool based on ADC threshold values was developed to aid cancer detection and progression monitoring. RESULTS: The ADC differentiated between control prostate ((1.86 ± 0.20) × 10(-3) mm(2) /s) and normal TRAMP prostate ((1.38 ± 0.10) × 10(-3) mm(2) /s) (P = 0.0001), between TRAMP prostate and well-differentiated cancer ((0.93 ± 0.18) × 10(-3) mm(2) /s) (P = 0.0006), and between well-differentiated cancer and poorly differentiated cancer ((0.63 ± 0.06) × 10(-3) mm(2) /s) (P = 0.02). CONCLUSION: DW-MRI is a tool for early detection of cancer, and discrimination between cancer stages in the TRAMP model. The incorporation of DW-MRI-based prostate cancer stratification and monitoring could increase the accuracy of preclinical trials using TRAMP mice.


Assuntos
Imagem de Difusão por Ressonância Magnética , Neoplasias da Próstata/patologia , Adenocarcinoma/diagnóstico por imagem , Adenocarcinoma/patologia , Animais , Automação , Biomarcadores Tumorais/metabolismo , Diferenciação Celular , Progressão da Doença , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Gradação de Tumores , Invasividade Neoplásica , Reconhecimento Automatizado de Padrão , Próstata/diagnóstico por imagem , Próstata/patologia , Neoplasias da Próstata/diagnóstico por imagem
6.
Stroke ; 45(9): 2777-85, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25052323

RESUMO

BACKGROUND AND PURPOSE: Increased susceptibility to excitotoxicity of the neonatal brain after hypoxia-ischemia (HI) may be caused by limited capacity of astrocytes for glutamate uptake, and mitochondrial failure probably plays a key role in the delayed injury cascade. Male infants have poorer outcome than females after HI, possibly linked to differential intermediary metabolism. METHODS: [1-(13)C]glucose and [1,2-(13)C]acetate were injected at zero, 6, and 48 hours after unilateral HI in 7-day-old rats. Intermediary metabolism was analyzed with magnetic resonance spectroscopy. RESULTS: Mitochondrial metabolism was generally reduced in the ipsilateral hemisphere for ≤6 hours after HI, whereas contralaterally, it was reduced in neurons but not in astrocytes. Transfer of glutamate from neurons to astrocytes was increased in the contralateral, but not in the ipsilateral hemisphere at 0 hour, and reduced bilaterally at 6 hours after HI. The transfer of glutamine from astrocytes to glutamatergic neurons was unaltered in both hemispheres, whereas the transfer of glutamine to GABAergic neurons was increased ipsilaterally at 0 hour. Anaplerosis (astrocytes) was decreased, whereas partial pyruvate recycling (astrocytes) was increased directly after HI. Male pups had lower astrocytic mitochondrial metabolism than females immediately after HI, whereas that of females was reduced longer and encompassed both neurons and astrocytes. CONCLUSIONS: The prolonged depression in mitochondrial metabolism indicates that mitochondria are vulnerable targets in the delayed injury after neonatal HI. The degree of astrocytic malfunction may be a valid indicator of outcome after hypoxic/HI brain injury and may be linked to the differential outcome in males and females.


Assuntos
Astrócitos/metabolismo , Encéfalo/crescimento & desenvolvimento , Hipóxia-Isquemia Encefálica/patologia , Neurônios/metabolismo , Acetatos/química , Animais , Encéfalo/metabolismo , Feminino , Neurônios GABAérgicos/metabolismo , Glucose/química , Glicólise , Espectroscopia de Ressonância Magnética , Masculino , Mitocôndrias/metabolismo , Ratos , Ratos Sprague-Dawley , Fatores Sexuais , Fatores de Tempo , Resultado do Tratamento
7.
Neurochem Res ; 39(3): 556-69, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-23504293

RESUMO

Glucose and acetate metabolism and the synthesis of amino acid neurotransmitters, anaplerosis, glutamate-glutamine cycling and the pentose phosphate pathway (PPP) have been extensively investigated in the adult, but not the neonatal rat brain. To do this, 7 day postnatal (P7) rats were injected with [1-(13)C]glucose and [1,2-(13)C]acetate and sacrificed 5, 10, 15, 30 and 45 min later. Adult rats were injected and sacrificed after 15 min. To analyse pyruvate carboxylation and PPP activity during development, P7 rats received [1,2-(13)C]glucose and were sacrificed 30 min later. Brain extracts were analysed using (1)H- and (13)C-NMR spectroscopy. Numerous differences in metabolism were found between the neonatal and adult brain. The neonatal brain contained lower levels of glutamate, aspartate and N-acetylaspartate but similar levels of GABA and glutamine per mg tissue. Metabolism of [1-(13)C]glucose at the acetyl CoA stage was reduced much more than that of [1,2-(13)C]acetate. The transfer of glutamate from neurons to astrocytes was much lower while transfer of glutamine from astrocytes to glutamatergic neurons was relatively higher. However, transport of glutamine from astrocytes to GABAergic neurons was lower. Using [1,2-(13)C]glucose it could be shown that despite much lower pyruvate carboxylation, relatively more pyruvate from glycolysis was directed towards anaplerosis than pyruvate dehydrogenation in astrocytes. Moreover, the ratio of PPP/glucose-metabolism was higher. These findings indicate that only the part of the glutamate-glutamine cycle that transfers glutamine from astrocytes to neurons is operating in the neonatal brain and that compared to adults, relatively more glucose is prioritised to PPP and pyruvate carboxylation. Our results may have implications for the capacity to protect the neonatal brain against excitotoxicity and oxidative stress.


Assuntos
Astrócitos/metabolismo , Encéfalo/metabolismo , Neurônios/metabolismo , Via de Pentose Fosfato/fisiologia , Piruvato Carboxilase/metabolismo , Ácido Pirúvico/metabolismo , Animais , Animais Recém-Nascidos , Encéfalo/crescimento & desenvolvimento , Ácido Glutâmico/metabolismo , Glutamina/administração & dosagem , Glutamina/metabolismo , Neurotransmissores/metabolismo , Ratos , Ratos Sprague-Dawley
8.
Pediatr Res ; 73(2): 171-9, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23174702

RESUMO

BACKGROUND: Hypoxia-ischemia (HI) induces delayed inflammation and long-term gray and white matter brain injury that may be altered by hyperoxia. METHODS: HI and 2 h of hyperoxia (100% O2) or room air (21% O2) in 7-d-old (P7) rats were studied by magnetic resonance imaging at 7 Tesla during 42 d: apparent diffusion coefficient (ADC) maps on day 1; T(1)-weighted manganese-enhanced images on day 7; diffusion tensor images on days 21 and 42; and T2 maps at all time points. RESULTS: The long-term brain tissue destruction on T2 maps was more severe in HI+hyperoxia than HI+room air. ADC was lower in HI+hyperoxia vs. HI+room air and sham and was correlated with long-term outcome. Manganese enhancement indicating inflammation was seen in both the groups along with more microglial activation in HI+hyperoxia on day 7. Fractional anisotropy (FA) in corpus callosum was lower and radial diffusivity was higher in HI+hyperoxia than that in HI+room air and sham on day 21. From day 21 to day 42, FA and radial diffusivity in HI+hyperoxia were unchanged, whereas in HI+room air, FA increased and radial diffusivity decreased to values similar to sham. CONCLUSION: Hyperoxia caused a more severe tissue destruction, delayed irreversible white matter injury, and increased inflammatory response resulting in a worsening in the trajectory of injury after HI in developing gray and white matter.


Assuntos
Encéfalo/patologia , Cloretos , Meios de Contraste , Imagem de Tensor de Difusão , Hiperóxia/patologia , Hipóxia-Isquemia Encefálica/patologia , Leucoencefalopatias/patologia , Compostos de Manganês , Animais , Cérebro/patologia , Corpo Caloso/patologia , Modelos Animais de Doenças , Hiperóxia/complicações , Hipóxia-Isquemia Encefálica/complicações , Leucoencefalopatias/etiologia , Ratos , Ratos Wistar , Índice de Gravidade de Doença , Fatores de Tempo
9.
Eur J Appl Physiol ; 113(6): 1405-14, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23232710

RESUMO

In this study, the effect of a simulated dive on rat brain was investigated using several magnetic resonance imaging (MRI)-methods and immunohistochemistry. Rats were randomly assigned to a dive- or a control group. The dive group was exposed to a simulated air dive to 600 kPa for 45 min. Pulmonary artery was monitored for vascular gas bubbles by ultrasound. MRI was performed 1 h after decompression and at one and 2 weeks after the dive with a different combination of MRI sequences at each time point. Two weeks after decompression, rats were sacrificed and brains were prepared for histology. Dived rats had a different time-curve for the dynamic contrast-enhanced MRI signal than controls with higher relative signal intensity, a tendency towards longer time to peak and a larger area under the curve for the whole brain on the acute MRI scan. On MRI, 1 and 2 weeks after dive, T2-maps showed no signal abnormalities or morphological changes. However, region of interest based measurements of T2 showed higher T2 in the brain stem among decompressed animals than controls after one and 2 weeks. Microscopical examination including immunohistochemistry did not reveal apparent structural or cellular injuries in any part of the rat brains. These observations indicate that severe decompression does not seem to cause any structural or cellular injury to the brain tissue of the rat, but may cause circulatory changes in the brain perfusion in the acute phase.


Assuntos
Córtex Cerebral/patologia , Circulação Cerebrovascular , Doença da Descompressão/patologia , Animais , Córtex Cerebral/irrigação sanguínea , Doença da Descompressão/fisiopatologia , Mergulho , Imageamento por Ressonância Magnética , Oxigênio/sangue , Artéria Pulmonar/diagnóstico por imagem , Ratos , Ratos Sprague-Dawley , Ultrassonografia
10.
J Alzheimers Dis ; 93(2): 411-419, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37038807

RESUMO

BACKGROUND: Early detection of amyloid-ß (Aß) aggregates is a critical step to improve the treatment of Alzheimer's disease (AD) because neuronal damage by the Aß aggregates occurs before clinical symptoms are apparent. We have previously shown that luminescent conjugated oligothiophenes (LCOs), which are highly specific towards protein aggregates of Aß, can be used to fluorescently label amyloid plaque in living rodents. OBJECTIVE: We hypothesize that the LCO can be used to target gadolinium to the amyloid plaque and hence make the plaque detectable by T1-weighted magnetic resonance imaging (MRI). METHODS: A novel LCO-gadolinium construct was synthesized to selectively bind to Aß plaques and give contrast in conventional T1-weighted MR images after intravenous injection in Tg-APPSwe mice. RESULTS: We found that mice with high plaque-burden could be identified using the LCO-Gd constructs by conventional MRI. CONCLUSION: Our study shows that MR imaging of amyloid plaques is challenging but feasible, and hence contrast-mediated MR imaging could be a valuable tool for early AD detection.


Assuntos
Doença de Alzheimer , Camundongos , Animais , Doença de Alzheimer/metabolismo , Placa Amiloide/patologia , Gadolínio/metabolismo , Camundongos Transgênicos , Peptídeos beta-Amiloides/metabolismo , Imageamento por Ressonância Magnética/métodos , Modelos Animais de Doenças , Encéfalo/patologia
11.
Eur J Neurosci ; 36(1): 2006-16, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22594966

RESUMO

Doxycycline may potentially be a neuroprotective treatment for neonatal hypoxic-ischemic brain injury through its anti-inflammatory effects. The aim of this study was to examine any long-term neuroprotection by doxycycline treatment on cerebral gray and white matter. Hypoxic-ischemic brain injury was induced in 7-day-old rats. Pups were treated with either doxycycline (HI+doxy) or saline (HI+vehicle) by intraperitoneal injection at 1 h after hypoxia-ischemia (HI). At 6 h after HI, MnCl(2) was injected intraperitoneally for later manganese-enhanced magnetic resonance imaging (MRI). MRI was performed with diffusion-weighted imaging on day 1 and T(1) -weighted imaging and diffusion tensor imaging at 7, 21 and 42 days after HI. Animals were killed after MRI on day 42 and histological examinations of the brains were performed. There was a tendency towards lower lesion volumes on diffusion maps among HI+doxy than HI+vehicle rats at 1 day after HI. Volumetric MRI showed increasing differences between groups with time after HI, with less cyst formation and less cerebral tissue loss among HI+doxy than HI+vehicle pups. HI+doxy pups had less manganese enhancement on day 7 after HI, indicating reduced inflammation. HI+doxy pups had higher fractional anisotropy on diffusion tensor imaging in major white matter tracts in the injured hemisphere than HI+vehicle pups, indicating less injury to white matter and better myelination. Histological examinations supported the MRI results. Lesion size on early MRI was highly correlated with final injury measures. In conclusion, a single dose of doxycycline reduced long-term cerebral tissue loss and white matter injury after neonatal HI, with an increasing effect of treatment with time after injury.


Assuntos
Cérebro/patologia , Doxiciclina/uso terapêutico , Hipóxia-Isquemia Encefálica/tratamento farmacológico , Fármacos Neuroprotetores/uso terapêutico , Animais , Animais Recém-Nascidos , Cérebro/lesões , Modelos Animais de Doenças , Hipóxia-Isquemia Encefálica/patologia , Estudos Longitudinais , Imageamento por Ressonância Magnética/métodos , Manganês/farmacologia , Fármacos Neuroprotetores/farmacologia , Ratos , Ratos Wistar
13.
World J Urol ; 28(4): 479-85, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20376453

RESUMO

PURPOSE: siRNA has been used successfully in loss-of-function studies in vitro, but neither in vivo nor in clinical applications. The aims of the present study were (1) to establish rat models for in vivo delivery of siRNA to bladder cancer, and (2) to identify potential targets for siRNA. METHODS: The rat models of human urinary carcinoma and rat urinary carcinoma cell line (AY-27) were induced by tobacco-related chemical carcinogens, either N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) or N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). A syngeneic orthotopic bladder cancer model was established by inoculation of AY-27 cells. A fluorescence-labelled negative control siRNA with cationic and neutral liposomes was tested both in vitro (AY-27 cells) and in vivo. RESULTS: siRNA was highly accumulated in the cancer cells as early as 12 h and remained at least for 24 h after a single dose in vivo. Numerous CD3+ T cells appeared mainly in the periphery area of the tumour. Bioinformatics analysis revealed a list of concordantly highly expressed genes, possible siRNA targets, in the animal models as well as human urinary carcinoma. Literature search on siRNA and bladder cancer provided a list of genes used as siRNA targets. CONCLUSION: The methodology and data presented in the present study provide a number of opportunities for basic research on urinary carcinogenesis and for translational research on evaluation of siRNA therapeutic strategies for urinary carcinoma in the native organ, where hormonal, neural and immunological processes more closely resemble the clinical situation.


Assuntos
Técnicas de Transferência de Genes , Terapia Genética/métodos , RNA Interferente Pequeno/farmacologia , Neoplasias da Bexiga Urinária , Administração Intravesical , Animais , Biópsia , Linhagem Celular Tumoral , Modelos Animais de Doenças , Feminino , Corantes Fluorescentes , Ratos , Ratos Endogâmicos F344 , Neoplasias da Bexiga Urinária/genética , Neoplasias da Bexiga Urinária/patologia , Neoplasias da Bexiga Urinária/terapia
14.
Eur J Pharm Biopharm ; 152: 248-256, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32439308

RESUMO

Melatonin is a neurohormone with potenial therapeutic effects in many diseases including neonatal hypoxic-ischemic (HI) brain injury. Due to limited solubility in water there is currently no clinically available melatonin formulation for parenteral use. Clinical use of melatonin has thus relied on oral administration, which in many cases is hampered by low and variable bioavailability. In animal treatment studies of neonatal HI, this issue have been circumvented by using parenteral administration of melatonin dissolved in ethanol (EtOH) or dimethyl sulfoxide (DMSO), solvents that are potentially neurotoxic, especially to the newborn brain. Thus, there is an urgent need for a non-toxic injectable melatonin formulation. The aim of this study was to develop such a formulation comprised of melatonin and biocompatible lipid-based nanoparticles with improved melatonin bioavailability. We herein report the development and characterization of an injectable system composed of melatonin and liposomes (LP) or oil-in-water nanoemulsions (NE). Nanoparticle characterization confirmed physicochemical stability over a week and an improvement with respect to melatonin solubilization in water (2.6 mg/mL in our injectable system). Determination of the in vitro release kinetics showed a prolonged release when melatonin is solubilized in nanoparticles (T1/2: 81 min vs 50 min vs 26 min for melatonin-LP, melatonin-NE, and melatonin-EtOH respectively). The pharmacokinetic (PK) parameters were confirmed in vivo in adult rats as similar melatonin levels detected in blood and indicated higher bioavailability in brain after intravenous administration of melatonin nanoformulations (10 mg/kg) in comparison to the free-melatonin administration. In conclusion, we have developed an organic solvent-free injectable formulation for melatonin by utilizing FDA-approved components, as a safe alternative for facilitating the potential of melatonin against variety of pathological conditions.


Assuntos
Melatonina/química , Nanopartículas/química , Solventes/química , Animais , Animais Recém-Nascidos , Disponibilidade Biológica , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Química Farmacêutica/métodos , Modelos Animais de Doenças , Emulsões/química , Feminino , Hipóxia-Isquemia Encefálica/tratamento farmacológico , Hipóxia-Isquemia Encefálica/metabolismo , Lipossomos/química , Melatonina/farmacocinética , Melatonina/farmacologia , Ratos , Ratos Sprague-Dawley , Solubilidade
15.
Neuroimage ; 45(3): 880-90, 2009 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-19138750

RESUMO

Hypoxic-ischemic injury (HI) to the neonatal brain results in delayed neuronal death with accompanying inflammation for days after the initial insult. The aim of this study was to depict delayed neuronal death after HI using Manganese-enhanced MRI (MEMRI) and to evaluate the specificity of MEMRI in detection of cells related to injury by comparison with histology and immunohistochemistry. 7-day-old Wistar rat pups were subjected to HI (occlusion of right carotid artery and 8% O(2) for 75 min). 16 HI (HI+Mn) and 6 sham operated (Sham+Mn) pups were injected with MnCl(2) (100 mM, 40 mg/kg) and 10 HI-pups (HI+Vehicle) received NaCl i.p. 6 h after HI. 3D T(1)-weighted images (FLASH) and 2D T(2)-maps (MSME) were acquired at 7 T 1, 3 and 7 days after HI. Pups were sacrificed after MR-scanning and brain slices were cut and stained for CD68, GFAP, MAP-2, Caspase-3 and Fluorojade B. No increased manganese-enhancement (ME) was detectable in the injured hemisphere on day 1 or 3 when immunohistochemistry showed massive ongoing neuronal death. 7 days after HI, increased ME was seen on T(1)-w images in parts of the injured cortex, hippocampus and thalamus among HI+Mn pups, but not among HI+Vehicle or Sham+Mn pups. Comparison with immunohistochemistry showed delayed neuronal death and inflammation in these areas with late ME. Areas with increased ME corresponded best with areas with high concentrations of activated microglia. Thus, late manganese-enhancement seems to be related to accumulation of manganese in activated microglia in areas of neuronal death rather than depicting neuronal death per se.


Assuntos
Cloretos , Hipóxia-Isquemia Encefálica/patologia , Aumento da Imagem/métodos , Imageamento por Ressonância Magnética/métodos , Compostos de Manganês , Animais , Animais Recém-Nascidos , Processamento de Imagem Assistida por Computador , Imuno-Histoquímica , Microglia/metabolismo , Neurônios/patologia , Ratos , Ratos Wistar
16.
PLoS One ; 14(12): e0225788, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31860692

RESUMO

Melatonin has potential neuroprotective capabilities after neonatal hypoxia-ischemia (HI), but long-term effects have not been investigated. We hypothesized that melatonin treatment directly after HI could protect against early and delayed brain injury. Unilateral HI brain injury was induced in postnatal day 7 rats. An intraperitoneal injection of either melatonin or vehicle was given at 0, 6 and 25 hours after hypoxia. In-vivo MRI was performed 1, 7, 20 and 43 days after HI, followed by histological analysis. Forelimb asymmetry and memory were assessed at 12-15 and at 36-43 days after HI. More melatonin treated than vehicle treated animals (54.5% vs 15.8%) developed a mild injury characterized by diffusion tensor values, brain volumes, histological scores and behavioral parameters closer to sham. However, on average, melatonin treatment resulted only in a tendency towards milder injury on T2-weighted MRI and apparent diffusion coefficient maps day 1 after HI, and not improved long-term outcome. These results indicate that the melatonin treatment regimen of 3 injections of 10 mg/kg within the first 25 hours only gave a transient and subtle neuroprotective effect, and may not have been sufficient to mitigate long-term brain injury development following HI.


Assuntos
Hipóxia-Isquemia Encefálica/tratamento farmacológico , Melatonina/uso terapêutico , Animais , Animais Recém-Nascidos , Corpo Caloso/efeitos dos fármacos , Corpo Caloso/patologia , Imagem de Tensor de Difusão , Feminino , Hipóxia-Isquemia Encefálica/diagnóstico por imagem , Imageamento por Ressonância Magnética , Masculino , Ratos , Ratos Sprague-Dawley , Substância Branca/efeitos dos fármacos , Substância Branca/lesões
17.
J Control Release ; 279: 292-305, 2018 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-29684498

RESUMO

Preclinical research has demonstrated that nanoparticles and macromolecules can accumulate in solid tumors due to the enhanced permeability and retention effect. However, drug loaded nanoparticles often fail to show increased efficacy in clinical trials. A better understanding of how tumor heterogeneity affects nanoparticle accumulation could help elucidate this discrepancy and help in patient selection for nanomedicine therapy. Here we studied five human tumor models with varying morphology and evaluated the accumulation of 100 nm polystyrene nanoparticles. Each tumor model was characterized in vivo using micro-computed tomography, contrast-enhanced ultrasound and diffusion-weighted and dynamic contrast-enhanced magnetic resonance imaging. Ex vivo, the tumors were sectioned for both fluorescence microscopy and histology. Nanoparticle uptake and distribution in the tumors were generally heterogeneous. Density of functional blood vessels measured by fluorescence microscopy correlated significantly (p = 0.0056) with nanoparticle accumulation and interestingly, inflow of microbubbles measured with ultrasound also showed a moderate but significant (p = 0.041) correlation with nanoparticle accumulation indicating that both amount of vessels and vessel morphology and perfusion predict nanoparticle accumulation. This indicates that blood vessel characterization using contrast-enhanced ultrasound imaging or other methods could be valuable for patient stratification for treatment with nanomedicines.


Assuntos
Nanopartículas/administração & dosagem , Neoplasias/metabolismo , Poliestirenos/química , Ultrassonografia/métodos , Animais , Linhagem Celular Tumoral , Meios de Contraste/química , Feminino , Humanos , Imageamento por Ressonância Magnética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Microbolhas , Microscopia de Fluorescência , Nanopartículas/metabolismo , Neoplasias/irrigação sanguínea , Neoplasias/diagnóstico por imagem , Microtomografia por Raio-X , Ensaios Antitumorais Modelo de Xenoenxerto
18.
ACS Appl Bio Mater ; 1(2): 462-472, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-35016367

RESUMO

Real time in vivo detection of Amyloid ß (Aß) deposits at an early stage may lead to faster and more conclusive diagnosis of Alzheimer's disease (AD) and can facilitate the follow up of the effect of therapeutic interventions. In this work, the capability of new hybrid nanomaterials to target and detect Aß aggregates using magnetic resonance (MRI) and fluorescence imaging is demonstrated. These smart contrast agents contain paramagnetic nanoparticles surrounded by luminescent conjugated oligothiophenes (LCOs) known to selectively bind to Aß aggregates, with emission spectra strongly dependent on their conformations, opening the possibilities for several fluorescence imaging modes for AD diagnostics. Relaxivity is evaluated in vitro and ex vivo. The capability of these contrast media to link to Aß fibrils in stained sections is revealed using transmission electron microscopy and fluorescence microscopy. Preliminary in vivo experiments show the ability of the contrast agent to diffuse through the blood-brain barrier of model animals and specifically stain amyloid deposits.

19.
PLoS One ; 12(9): e0185202, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28934366

RESUMO

Melatonin is a promising neuroprotective agent after perinatal hypoxic-ischemic (HI) brain injury. We used in-vivo 1H magnetic resonance spectroscopy to investigate effects of melatonin treatment on brain metabolism after HI. Postnatal day 7 Sprague-Dawley rats with unilateral HI brain injury were treated with either melatonin 10 mg/kg dissolved in phosphate-buffered saline (PBS) with 5% dimethyl sulfoxide (DMSO) or vehicle (5% DMSO and/or PBS) directly and at 6 hours after HI. 1H MR spectra from the thalamus in the ipsilateral and contralateral hemisphere were acquired 1 day after HI. Our results showed that injured animals had a distinct metabolic profile in the ipsilateral thalamus compared to sham with low concentrations of total creatine, choline, N-acetyl aspartate (NAA), and high concentrations of lipids. A majority of the melatonin-treated animals had a metabolic profile characterized by higher total creatine, choline, NAA and lower lipid levels than other HI animals. When comparing absolute concentrations, melatonin treatment resulted in higher glutamine levels and lower lipid concentrations compared to DMSO treatment as well as higher macromolecule levels compared to PBS treatment day 1 after HI. DMSO treated animals had lower concentrations of glucose, creatine, phosphocholine and macromolecules compared to sham animals. In conclusion, the neuroprotective effects of melatonin were reflected in a more favorable metabolic profile including reduced lipid levels that likely represents reduced cell injury. Neuroprotective effects may also be related to the influence of melatonin on glutamate/glutamine metabolism. The modulatory effects of the solvent DMSO on cerebral energy metabolism might have masked additional beneficial effects of melatonin.


Assuntos
Hipóxia-Isquemia Encefálica/metabolismo , Melatonina/farmacologia , Fármacos Neuroprotetores/farmacologia , Animais , Animais Recém-Nascidos , Relação Dose-Resposta a Droga , Espectroscopia de Ressonância Magnética , Ratos , Ratos Sprague-Dawley , Tálamo/efeitos dos fármacos , Tálamo/metabolismo
20.
J Control Release ; 220(Pt A): 287-294, 2015 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-26518721

RESUMO

The blood-brain barrier (BBB) constitutes a significant obstacle for the delivery of drugs into the central nervous system (CNS). Nanoparticles have been able to partly overcome this obstacle and can thus improve drug delivery across the BBB. Furthermore, focused ultrasound in combination with gas filled microbubbles has opened the BBB in a temporospatial manner in animal models, thus facilitating drug delivery across the BBB. In the current study we combine these two approaches in our quest to develop a novel, generic method for drug delivery across the BBB and into the CNS. Nanoparticles were synthesized using the polymer poly(butyl cyanoacrylate) (PBCA), and such nanoparticles have been reported to cross the BBB to some extent. Together with proteins, these nanoparticles self-assemble into microbubbles. Using these novel microbubbles in combination with focused ultrasound, we successfully and safely opened the BBB transiently in healthy rats. Furthermore, we also demonstrated that the nanoparticles could cross the BBB and deliver a model drug into the CNS.


Assuntos
Barreira Hematoencefálica/metabolismo , Permeabilidade Capilar , Portadores de Fármacos , Embucrilato/química , Corantes Fluorescentes/metabolismo , Microbolhas , Nanopartículas , Oxazinas/metabolismo , Ultrassom/métodos , Animais , Composição de Medicamentos , Feminino , Corantes Fluorescentes/química , Imageamento por Ressonância Magnética , Nanotecnologia , Oxazinas/química , Ratos Sprague-Dawley
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