Purpose: It is anticipated that nanostructures will play a crucial role in medicine by serving as... more Purpose: It is anticipated that nanostructures will play a crucial role in medicine by serving as carriers for drugs and imaging agents that will bind to targets on injured tissue (1). It is therefore essential that we are able to detect these potential therapeutic agents. In our project, we are using a strategy based on the multifuntionalisation of superparamagnetic iron oxide nanoparticles (SPIO) combining diagnostic and therapeutic techniques against breast and pancreatic cancer (2). The aim of the present study was to assess and validate the particle electron paramagnetic resonance (pEPR) technique in a biodistribution study by means of in vivo MRI scans, and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), as analytical gold standard technique. Here we present an alternative analytical method for detecting SPIO in vitro and ex vivo that is inexpensive and rapid (no sample preparation). It is based on electron paramagnetic resonance (3) and selectively measuring the magnetization of the SPIO. In pEPR a radio frequency excitation is applied at the resonant frequency and the received signal is a measure for the amount of SPIO present in the sample. Materials and Methods: Quantitative validation of the pEPR technique was carried out by comparing pEPR and ICP-MS measurements using reference samples (in blood, plasma and saline) containing known quantities of SPIO. The concentrations are expressed in mg Fe/L and the difference measured between controls and samples represents the iron from SPIO. To assess the biodistribution of our DMSA coated iron oxide core nanoparticles (4), BALBc mice (25 ± 3 g) were anesthetized with isofluorane, positioned within a 7 T Bruker magnet and a baseline MRI was acquired. A second scan was performed at different time points (3, 24, 48, 96 hours) after the tail vein administration of either 100 μl of solution of SPIO (10 mg Fe/ml) or saline (vehicle control). Post scanning, mice were sacrificed and the organs harvested. The SPIO related signal change was evaluated on a same slice, which was located covering the organs of interest (heart, liver, spleen, lungs and kidneys). The baseline and SPIO images were co-registered using a control point method and an affine transformation in a script written in MATLAB ® . The intensity of the signal in a given Region of Interest (ROI) was first normalized using a reference signal from a water tube located beside the animal. Relative Signal Enhancement (RSE) was defined as the relative change in normalized signal intensity (SI) pre and post SPIO injection [RSE (%) = 100 x (1-SI post/SI pre)]. A Turbo RARE T2-weighted sequence (TR/TE 4200/23.5 ms, FA 180°, FOV 6 cm, 5 averages, 35 slices, resolution: 306 μm/pixel) was used to record 2D images. The quantity of SPIO in the harvested organs was evaluated by pEPR. The concentration of SPIO is expressed in mg Fe/kg of organ and each organ is compared to a control across the different time points. The difference measured between organ controls and organ injected animals represents the iron amount from SPIO.
Primary mitochondrial disorders occur at a prevalence of one in 10 000; ∼50% of these demonstrate... more Primary mitochondrial disorders occur at a prevalence of one in 10 000; ∼50% of these demonstrate ocular pathology. Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial disorder. LHON results from retinal ganglion cell pathology, which leads to optic nerve degeneration and blindness. Over 95% of cases result from one of the three common mutations in mitochondrial genes MTND1, MTND4 and MTND6, which encode elements of the complex I respiratory chain. Various therapies for LHON are in development, for example, intravitreal injection of adeno-associated virus carrying either the yeast NDI1 gene or a specific subunit of mammalian Complex I have shown visual improvement in animal models. Given the course of LHON, it is likely that in many cases prompt administration may be necessary before widespread cell death. An alternative approach for therapy may be the use of stem cells to protect visual function; this has been evaluated by us in a rotenone-induced model of LHON. Freshly dissected embryonic retinal cells do not integrate into the ganglion cell layer (GCL), unlike similarly obtained photoreceptor precursors. However, cultured retinal progenitor cells can integrate in close proximity to the GCL, and act to preserve retinal function as assessed by manganese-enhanced magnetic resonance imaging, optokinetic responses and ganglion cell counts. Cell therapies for LHON therefore represent a promising therapeutic approach, and may be of particular utility in treating more advanced disease.
Several forms of hippocampal-dependent learning rely upon activation of the N-methyl-Daspartate (... more Several forms of hippocampal-dependent learning rely upon activation of the N-methyl-Daspartate (NMDA) subtype of glutamate receptor. Here we have investigated the effects of administration of the NMDA receptor antagonist (±)-3-(2-carboxypiperazin-4-yl)propyl-1phosphonic acid (CPP) on the performance of rats in an object displacement task and the possible role of extracellular signal-regulated kinase (ERK) in this form of learning. The data show that rats injected intraperitoneally with CPP (10 mg/kg) before, but not after, training in the object displacement task displayed impairments in spatial learning when compared with saline-injected controls. The NMDAR may thus be involved in the acquisition, but not the consolidation, of this type of memory. In addition, a significant positive correlation was observed between learning and the expression of activated ERK in the dentate gyrus. No such correlation was apparent in the rest of the hippocampal formation. This study implicates the NMDARs in the acquisition phase of spatial learning and provides evidence for a role for ERK in spatial learning in the dentate gyrus of the rat. ava i l a b l e a t w w w. s c i e n c e d i r e c t . c o m w w w. e l s ev i e r. c o m / l o c a t e / b r a i n r e s
A challenge exists to produce dry powder inhaler (DPI) formulations with appropriate formulation ... more A challenge exists to produce dry powder inhaler (DPI) formulations with appropriate formulation stability, biological activity and suitable physicochemical and aerosolisation characteristics that provide a viable alternative to parenteral formulations. The present study aimed to produce sugar-based nanoporous/nanoparticulate microparticles (NPMPs) loaded with a therapeutic peptidesalmon calcitonin (sCT). The physicochemical properties of the powders and their suitability for pulmonary delivery of sCT were determined. Production of powders composed of sCT loaded into raffinose or trehalose with or without hydroxypropyl-b-cyclodextrin was carried out using a laboratory scale spray dryer. Spray dried microparticles were spherical, porous and of small geometric size ( 2 mm). Aerodynamic assessment showed that the fine particle fraction (FPF) less than 5 mm ranged from 45 to 86%, depending on the formulation. The mass median aerodynamic diameter (MMAD) varied between 1.9 and 4.7 mm. Compared to unprocessed sCT, sCT:raffinose composite systems presented a bioactivity of approximately 100% and sCT:trehalose composite systems between 70-90% after spray drying. Storage stability studies demonstrated composite systems with raffinose to be more stable than those containing trehalose. These sugar-based salmon calcitonin-loaded NPMPs retain reasonable sCT bioactivity and have micromeritic and physicochemical properties which indicate their suitability for pulmonary delivery. Formulations presented a similar pharmacokinetic profile to sCT solution. Hence the advantage of a dry powder formulation is its non-invasive delivery route and ease of administration of the sCT.
JAK4D, a first-in-class thyrotropin-releasing hormone (TRH)-based compound, is a prospective ther... more JAK4D, a first-in-class thyrotropin-releasing hormone (TRH)-based compound, is a prospective therapeutic candidate offering a multifaceted approach to treating neurodegeneration and other CNS conditions. The purpose of these studies was to determine the ability of JAK4D to bind to TRH receptors in human brain and to evaluate its neuropharmacological effects in neurodegenerative animal models. Additionally, JAK4D brain permeation was examined in mouse, and initial toxicology was assessed in vivo and in vitro. We report that JAK4D bound selectively with nanomolar affinity to native TRH receptors in human hippocampal tissue and showed for the first time that these receptors are pharmacologically distinct from TRH receptors in human pituitary, thus revealing a new TRH receptor subtype which represents a promising neurotherapeutic target in human brain. Systemic administration of JAK4D elicited statistically significant and clinically-relevant neuroprotective effects in three established...
Purpose: It is anticipated that nanostructures will play a crucial role in medicine by serving as... more Purpose: It is anticipated that nanostructures will play a crucial role in medicine by serving as carriers for drugs and imaging agents that will bind to targets on injured tissue (1). It is therefore essential that we are able to detect these potential therapeutic agents. In our project, we are using a strategy based on the multifuntionalisation of superparamagnetic iron oxide nanoparticles (SPIO) combining diagnostic and therapeutic techniques against breast and pancreatic cancer (2). The aim of the present study was to assess and validate the particle electron paramagnetic resonance (pEPR) technique in a biodistribution study by means of in vivo MRI scans, and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), as analytical gold standard technique. Here we present an alternative analytical method for detecting SPIO in vitro and ex vivo that is inexpensive and rapid (no sample preparation). It is based on electron paramagnetic resonance (3) and selectively measuring the magnetization of the SPIO. In pEPR a radio frequency excitation is applied at the resonant frequency and the received signal is a measure for the amount of SPIO present in the sample. Materials and Methods: Quantitative validation of the pEPR technique was carried out by comparing pEPR and ICP-MS measurements using reference samples (in blood, plasma and saline) containing known quantities of SPIO. The concentrations are expressed in mg Fe/L and the difference measured between controls and samples represents the iron from SPIO. To assess the biodistribution of our DMSA coated iron oxide core nanoparticles (4), BALBc mice (25 ± 3 g) were anesthetized with isofluorane, positioned within a 7 T Bruker magnet and a baseline MRI was acquired. A second scan was performed at different time points (3, 24, 48, 96 hours) after the tail vein administration of either 100 μl of solution of SPIO (10 mg Fe/ml) or saline (vehicle control). Post scanning, mice were sacrificed and the organs harvested. The SPIO related signal change was evaluated on a same slice, which was located covering the organs of interest (heart, liver, spleen, lungs and kidneys). The baseline and SPIO images were co-registered using a control point method and an affine transformation in a script written in MATLAB ® . The intensity of the signal in a given Region of Interest (ROI) was first normalized using a reference signal from a water tube located beside the animal. Relative Signal Enhancement (RSE) was defined as the relative change in normalized signal intensity (SI) pre and post SPIO injection [RSE (%) = 100 x (1-SI post/SI pre)]. A Turbo RARE T2-weighted sequence (TR/TE 4200/23.5 ms, FA 180°, FOV 6 cm, 5 averages, 35 slices, resolution: 306 μm/pixel) was used to record 2D images. The quantity of SPIO in the harvested organs was evaluated by pEPR. The concentration of SPIO is expressed in mg Fe/kg of organ and each organ is compared to a control across the different time points. The difference measured between organ controls and organ injected animals represents the iron amount from SPIO.
Primary mitochondrial disorders occur at a prevalence of one in 10 000; ∼50% of these demonstrate... more Primary mitochondrial disorders occur at a prevalence of one in 10 000; ∼50% of these demonstrate ocular pathology. Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial disorder. LHON results from retinal ganglion cell pathology, which leads to optic nerve degeneration and blindness. Over 95% of cases result from one of the three common mutations in mitochondrial genes MTND1, MTND4 and MTND6, which encode elements of the complex I respiratory chain. Various therapies for LHON are in development, for example, intravitreal injection of adeno-associated virus carrying either the yeast NDI1 gene or a specific subunit of mammalian Complex I have shown visual improvement in animal models. Given the course of LHON, it is likely that in many cases prompt administration may be necessary before widespread cell death. An alternative approach for therapy may be the use of stem cells to protect visual function; this has been evaluated by us in a rotenone-induced model of LHON. Freshly dissected embryonic retinal cells do not integrate into the ganglion cell layer (GCL), unlike similarly obtained photoreceptor precursors. However, cultured retinal progenitor cells can integrate in close proximity to the GCL, and act to preserve retinal function as assessed by manganese-enhanced magnetic resonance imaging, optokinetic responses and ganglion cell counts. Cell therapies for LHON therefore represent a promising therapeutic approach, and may be of particular utility in treating more advanced disease.
Lung parenchyma remains one of the most difficult tissues to be imaged by means of magnetic reson... more Lung parenchyma remains one of the most difficult tissues to be imaged by means of magnetic resonance imaging (MRI). Several MRI techniques are routinely used for lung imaging. However, manganese-enhancement MRI (MEMRI) technique has not been associated with pulmonary MRI. Here, we evaluated T 1 -enhancement in the rat lung after a manganese instillation, using a 4.7 T magnet with a radial ultrashort echo time sequence. Our data showed that the signal intensity was increased in lungs receiving a manganese solution compared with a control solution to the lungs. MR signal enhancements above 30% were measured in lung parenchyma following 200 ml instillation of a 1 mM manganese chloride solution. MEMRI, therefore, may be a useful novel tool for enhancing signal intensity and image contrast in lung tissue.
Several forms of hippocampal-dependent learning rely upon activation of the N-methyl-Daspartate (... more Several forms of hippocampal-dependent learning rely upon activation of the N-methyl-Daspartate (NMDA) subtype of glutamate receptor. Here we have investigated the effects of administration of the NMDA receptor antagonist (±)-3-(2-carboxypiperazin-4-yl)propyl-1phosphonic acid (CPP) on the performance of rats in an object displacement task and the possible role of extracellular signal-regulated kinase (ERK) in this form of learning. The data show that rats injected intraperitoneally with CPP (10 mg/kg) before, but not after, training in the object displacement task displayed impairments in spatial learning when compared with saline-injected controls. The NMDAR may thus be involved in the acquisition, but not the consolidation, of this type of memory. In addition, a significant positive correlation was observed between learning and the expression of activated ERK in the dentate gyrus. No such correlation was apparent in the rest of the hippocampal formation. This study implicates the NMDARs in the acquisition phase of spatial learning and provides evidence for a role for ERK in spatial learning in the dentate gyrus of the rat. ava i l a b l e a t w w w. s c i e n c e d i r e c t . c o m w w w. e l s ev i e r. c o m / l o c a t e / b r a i n r e s
Inhalation of therapeutic aerosols is a long-established means of drug delivery to the lungs or t... more Inhalation of therapeutic aerosols is a long-established means of drug delivery to the lungs or to the systemic circulation. In addition to solutions, suspensions, and particulates, liposomal formulations are being developed for aerosol administration. In this report, we investigated the membrane integrity of liposomes encapsulating the fluorescent model compound, calcein, after nebulization using two novel aerosolization devices, the Aeroneb Pro vibrating-mesh nebulizer (Aerogen, Dangan, Ireland) and the AeroProbe intracorporeal nebulizing catheter (Trudell Medical Corporation, London, Ontario, Canada). The influence of lipid composition and lamellarity on the stability of the vesicles was investigated by measuring changes in median diameter, zeta-potential, and calcein retention. Both nebulizers were able to successfully aerosolise 1.5 mL of liposome suspension in a short period of time. The diameter and zeta-potential of the liposomes was preserved upon nebulization, and the calcein retention was above 70% in all cases. It can, hence, be concluded that both systems, the Aeroneb Pro and the AeroProbe, are well suited for the pulmonary delivery of liposomal formulations, with the AeroProbe having the additional advantage of allowing targeted delivery into the select regions of the lungs with a high degree of efficiency and control.
Purpose: It is anticipated that nanostructures will play a crucial role in medicine by serving as... more Purpose: It is anticipated that nanostructures will play a crucial role in medicine by serving as carriers for drugs and imaging agents that will bind to targets on injured tissue (1). It is therefore essential that we are able to detect these potential therapeutic agents. In our project, we are using a strategy based on the multifuntionalisation of superparamagnetic iron oxide nanoparticles (SPIO) combining diagnostic and therapeutic techniques against breast and pancreatic cancer (2). The aim of the present study was to assess and validate the particle electron paramagnetic resonance (pEPR) technique in a biodistribution study by means of in vivo MRI scans, and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), as analytical gold standard technique. Here we present an alternative analytical method for detecting SPIO in vitro and ex vivo that is inexpensive and rapid (no sample preparation). It is based on electron paramagnetic resonance (3) and selectively measuring the magnetization of the SPIO. In pEPR a radio frequency excitation is applied at the resonant frequency and the received signal is a measure for the amount of SPIO present in the sample. Materials and Methods: Quantitative validation of the pEPR technique was carried out by comparing pEPR and ICP-MS measurements using reference samples (in blood, plasma and saline) containing known quantities of SPIO. The concentrations are expressed in mg Fe/L and the difference measured between controls and samples represents the iron from SPIO. To assess the biodistribution of our DMSA coated iron oxide core nanoparticles (4), BALBc mice (25 ± 3 g) were anesthetized with isofluorane, positioned within a 7 T Bruker magnet and a baseline MRI was acquired. A second scan was performed at different time points (3, 24, 48, 96 hours) after the tail vein administration of either 100 μl of solution of SPIO (10 mg Fe/ml) or saline (vehicle control). Post scanning, mice were sacrificed and the organs harvested. The SPIO related signal change was evaluated on a same slice, which was located covering the organs of interest (heart, liver, spleen, lungs and kidneys). The baseline and SPIO images were co-registered using a control point method and an affine transformation in a script written in MATLAB ® . The intensity of the signal in a given Region of Interest (ROI) was first normalized using a reference signal from a water tube located beside the animal. Relative Signal Enhancement (RSE) was defined as the relative change in normalized signal intensity (SI) pre and post SPIO injection [RSE (%) = 100 x (1-SI post/SI pre)]. A Turbo RARE T2-weighted sequence (TR/TE 4200/23.5 ms, FA 180°, FOV 6 cm, 5 averages, 35 slices, resolution: 306 μm/pixel) was used to record 2D images. The quantity of SPIO in the harvested organs was evaluated by pEPR. The concentration of SPIO is expressed in mg Fe/kg of organ and each organ is compared to a control across the different time points. The difference measured between organ controls and organ injected animals represents the iron amount from SPIO.
Primary mitochondrial disorders occur at a prevalence of one in 10 000; ∼50% of these demonstrate... more Primary mitochondrial disorders occur at a prevalence of one in 10 000; ∼50% of these demonstrate ocular pathology. Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial disorder. LHON results from retinal ganglion cell pathology, which leads to optic nerve degeneration and blindness. Over 95% of cases result from one of the three common mutations in mitochondrial genes MTND1, MTND4 and MTND6, which encode elements of the complex I respiratory chain. Various therapies for LHON are in development, for example, intravitreal injection of adeno-associated virus carrying either the yeast NDI1 gene or a specific subunit of mammalian Complex I have shown visual improvement in animal models. Given the course of LHON, it is likely that in many cases prompt administration may be necessary before widespread cell death. An alternative approach for therapy may be the use of stem cells to protect visual function; this has been evaluated by us in a rotenone-induced model of LHON. Freshly dissected embryonic retinal cells do not integrate into the ganglion cell layer (GCL), unlike similarly obtained photoreceptor precursors. However, cultured retinal progenitor cells can integrate in close proximity to the GCL, and act to preserve retinal function as assessed by manganese-enhanced magnetic resonance imaging, optokinetic responses and ganglion cell counts. Cell therapies for LHON therefore represent a promising therapeutic approach, and may be of particular utility in treating more advanced disease.
Several forms of hippocampal-dependent learning rely upon activation of the N-methyl-Daspartate (... more Several forms of hippocampal-dependent learning rely upon activation of the N-methyl-Daspartate (NMDA) subtype of glutamate receptor. Here we have investigated the effects of administration of the NMDA receptor antagonist (±)-3-(2-carboxypiperazin-4-yl)propyl-1phosphonic acid (CPP) on the performance of rats in an object displacement task and the possible role of extracellular signal-regulated kinase (ERK) in this form of learning. The data show that rats injected intraperitoneally with CPP (10 mg/kg) before, but not after, training in the object displacement task displayed impairments in spatial learning when compared with saline-injected controls. The NMDAR may thus be involved in the acquisition, but not the consolidation, of this type of memory. In addition, a significant positive correlation was observed between learning and the expression of activated ERK in the dentate gyrus. No such correlation was apparent in the rest of the hippocampal formation. This study implicates the NMDARs in the acquisition phase of spatial learning and provides evidence for a role for ERK in spatial learning in the dentate gyrus of the rat. ava i l a b l e a t w w w. s c i e n c e d i r e c t . c o m w w w. e l s ev i e r. c o m / l o c a t e / b r a i n r e s
A challenge exists to produce dry powder inhaler (DPI) formulations with appropriate formulation ... more A challenge exists to produce dry powder inhaler (DPI) formulations with appropriate formulation stability, biological activity and suitable physicochemical and aerosolisation characteristics that provide a viable alternative to parenteral formulations. The present study aimed to produce sugar-based nanoporous/nanoparticulate microparticles (NPMPs) loaded with a therapeutic peptidesalmon calcitonin (sCT). The physicochemical properties of the powders and their suitability for pulmonary delivery of sCT were determined. Production of powders composed of sCT loaded into raffinose or trehalose with or without hydroxypropyl-b-cyclodextrin was carried out using a laboratory scale spray dryer. Spray dried microparticles were spherical, porous and of small geometric size ( 2 mm). Aerodynamic assessment showed that the fine particle fraction (FPF) less than 5 mm ranged from 45 to 86%, depending on the formulation. The mass median aerodynamic diameter (MMAD) varied between 1.9 and 4.7 mm. Compared to unprocessed sCT, sCT:raffinose composite systems presented a bioactivity of approximately 100% and sCT:trehalose composite systems between 70-90% after spray drying. Storage stability studies demonstrated composite systems with raffinose to be more stable than those containing trehalose. These sugar-based salmon calcitonin-loaded NPMPs retain reasonable sCT bioactivity and have micromeritic and physicochemical properties which indicate their suitability for pulmonary delivery. Formulations presented a similar pharmacokinetic profile to sCT solution. Hence the advantage of a dry powder formulation is its non-invasive delivery route and ease of administration of the sCT.
JAK4D, a first-in-class thyrotropin-releasing hormone (TRH)-based compound, is a prospective ther... more JAK4D, a first-in-class thyrotropin-releasing hormone (TRH)-based compound, is a prospective therapeutic candidate offering a multifaceted approach to treating neurodegeneration and other CNS conditions. The purpose of these studies was to determine the ability of JAK4D to bind to TRH receptors in human brain and to evaluate its neuropharmacological effects in neurodegenerative animal models. Additionally, JAK4D brain permeation was examined in mouse, and initial toxicology was assessed in vivo and in vitro. We report that JAK4D bound selectively with nanomolar affinity to native TRH receptors in human hippocampal tissue and showed for the first time that these receptors are pharmacologically distinct from TRH receptors in human pituitary, thus revealing a new TRH receptor subtype which represents a promising neurotherapeutic target in human brain. Systemic administration of JAK4D elicited statistically significant and clinically-relevant neuroprotective effects in three established...
Purpose: It is anticipated that nanostructures will play a crucial role in medicine by serving as... more Purpose: It is anticipated that nanostructures will play a crucial role in medicine by serving as carriers for drugs and imaging agents that will bind to targets on injured tissue (1). It is therefore essential that we are able to detect these potential therapeutic agents. In our project, we are using a strategy based on the multifuntionalisation of superparamagnetic iron oxide nanoparticles (SPIO) combining diagnostic and therapeutic techniques against breast and pancreatic cancer (2). The aim of the present study was to assess and validate the particle electron paramagnetic resonance (pEPR) technique in a biodistribution study by means of in vivo MRI scans, and Inductively Coupled Plasma Mass Spectrometry (ICP-MS), as analytical gold standard technique. Here we present an alternative analytical method for detecting SPIO in vitro and ex vivo that is inexpensive and rapid (no sample preparation). It is based on electron paramagnetic resonance (3) and selectively measuring the magnetization of the SPIO. In pEPR a radio frequency excitation is applied at the resonant frequency and the received signal is a measure for the amount of SPIO present in the sample. Materials and Methods: Quantitative validation of the pEPR technique was carried out by comparing pEPR and ICP-MS measurements using reference samples (in blood, plasma and saline) containing known quantities of SPIO. The concentrations are expressed in mg Fe/L and the difference measured between controls and samples represents the iron from SPIO. To assess the biodistribution of our DMSA coated iron oxide core nanoparticles (4), BALBc mice (25 ± 3 g) were anesthetized with isofluorane, positioned within a 7 T Bruker magnet and a baseline MRI was acquired. A second scan was performed at different time points (3, 24, 48, 96 hours) after the tail vein administration of either 100 μl of solution of SPIO (10 mg Fe/ml) or saline (vehicle control). Post scanning, mice were sacrificed and the organs harvested. The SPIO related signal change was evaluated on a same slice, which was located covering the organs of interest (heart, liver, spleen, lungs and kidneys). The baseline and SPIO images were co-registered using a control point method and an affine transformation in a script written in MATLAB ® . The intensity of the signal in a given Region of Interest (ROI) was first normalized using a reference signal from a water tube located beside the animal. Relative Signal Enhancement (RSE) was defined as the relative change in normalized signal intensity (SI) pre and post SPIO injection [RSE (%) = 100 x (1-SI post/SI pre)]. A Turbo RARE T2-weighted sequence (TR/TE 4200/23.5 ms, FA 180°, FOV 6 cm, 5 averages, 35 slices, resolution: 306 μm/pixel) was used to record 2D images. The quantity of SPIO in the harvested organs was evaluated by pEPR. The concentration of SPIO is expressed in mg Fe/kg of organ and each organ is compared to a control across the different time points. The difference measured between organ controls and organ injected animals represents the iron amount from SPIO.
Primary mitochondrial disorders occur at a prevalence of one in 10 000; ∼50% of these demonstrate... more Primary mitochondrial disorders occur at a prevalence of one in 10 000; ∼50% of these demonstrate ocular pathology. Leber hereditary optic neuropathy (LHON) is the most common primary mitochondrial disorder. LHON results from retinal ganglion cell pathology, which leads to optic nerve degeneration and blindness. Over 95% of cases result from one of the three common mutations in mitochondrial genes MTND1, MTND4 and MTND6, which encode elements of the complex I respiratory chain. Various therapies for LHON are in development, for example, intravitreal injection of adeno-associated virus carrying either the yeast NDI1 gene or a specific subunit of mammalian Complex I have shown visual improvement in animal models. Given the course of LHON, it is likely that in many cases prompt administration may be necessary before widespread cell death. An alternative approach for therapy may be the use of stem cells to protect visual function; this has been evaluated by us in a rotenone-induced model of LHON. Freshly dissected embryonic retinal cells do not integrate into the ganglion cell layer (GCL), unlike similarly obtained photoreceptor precursors. However, cultured retinal progenitor cells can integrate in close proximity to the GCL, and act to preserve retinal function as assessed by manganese-enhanced magnetic resonance imaging, optokinetic responses and ganglion cell counts. Cell therapies for LHON therefore represent a promising therapeutic approach, and may be of particular utility in treating more advanced disease.
Lung parenchyma remains one of the most difficult tissues to be imaged by means of magnetic reson... more Lung parenchyma remains one of the most difficult tissues to be imaged by means of magnetic resonance imaging (MRI). Several MRI techniques are routinely used for lung imaging. However, manganese-enhancement MRI (MEMRI) technique has not been associated with pulmonary MRI. Here, we evaluated T 1 -enhancement in the rat lung after a manganese instillation, using a 4.7 T magnet with a radial ultrashort echo time sequence. Our data showed that the signal intensity was increased in lungs receiving a manganese solution compared with a control solution to the lungs. MR signal enhancements above 30% were measured in lung parenchyma following 200 ml instillation of a 1 mM manganese chloride solution. MEMRI, therefore, may be a useful novel tool for enhancing signal intensity and image contrast in lung tissue.
Several forms of hippocampal-dependent learning rely upon activation of the N-methyl-Daspartate (... more Several forms of hippocampal-dependent learning rely upon activation of the N-methyl-Daspartate (NMDA) subtype of glutamate receptor. Here we have investigated the effects of administration of the NMDA receptor antagonist (±)-3-(2-carboxypiperazin-4-yl)propyl-1phosphonic acid (CPP) on the performance of rats in an object displacement task and the possible role of extracellular signal-regulated kinase (ERK) in this form of learning. The data show that rats injected intraperitoneally with CPP (10 mg/kg) before, but not after, training in the object displacement task displayed impairments in spatial learning when compared with saline-injected controls. The NMDAR may thus be involved in the acquisition, but not the consolidation, of this type of memory. In addition, a significant positive correlation was observed between learning and the expression of activated ERK in the dentate gyrus. No such correlation was apparent in the rest of the hippocampal formation. This study implicates the NMDARs in the acquisition phase of spatial learning and provides evidence for a role for ERK in spatial learning in the dentate gyrus of the rat. ava i l a b l e a t w w w. s c i e n c e d i r e c t . c o m w w w. e l s ev i e r. c o m / l o c a t e / b r a i n r e s
Inhalation of therapeutic aerosols is a long-established means of drug delivery to the lungs or t... more Inhalation of therapeutic aerosols is a long-established means of drug delivery to the lungs or to the systemic circulation. In addition to solutions, suspensions, and particulates, liposomal formulations are being developed for aerosol administration. In this report, we investigated the membrane integrity of liposomes encapsulating the fluorescent model compound, calcein, after nebulization using two novel aerosolization devices, the Aeroneb Pro vibrating-mesh nebulizer (Aerogen, Dangan, Ireland) and the AeroProbe intracorporeal nebulizing catheter (Trudell Medical Corporation, London, Ontario, Canada). The influence of lipid composition and lamellarity on the stability of the vesicles was investigated by measuring changes in median diameter, zeta-potential, and calcein retention. Both nebulizers were able to successfully aerosolise 1.5 mL of liposome suspension in a short period of time. The diameter and zeta-potential of the liposomes was preserved upon nebulization, and the calcein retention was above 70% in all cases. It can, hence, be concluded that both systems, the Aeroneb Pro and the AeroProbe, are well suited for the pulmonary delivery of liposomal formulations, with the AeroProbe having the additional advantage of allowing targeted delivery into the select regions of the lungs with a high degree of efficiency and control.
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Papers by Oliviero Gobbo