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Soares G, Pinto L, Liebl M, Biasotti G, Prospero A, Stoppa E, Bakuzis A, Baffa O, Wiekhorst F, Miranda JRA. Quantitative imaging of magnetic nanoparticles in an unshielded environment using a large AC susceptibility array. J Biol Eng 2022; 16:25. [PMID: 36221096 PMCID: PMC9552418 DOI: 10.1186/s13036-022-00305-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 09/26/2022] [Indexed: 11/29/2022] Open
Abstract
Background Non-invasive magnetic imaging techniques are necessary to assist magnetic nanoparticles in biomedical applications, mainly detecting their distribution inside the body. In Alternating Current Biosusceptometry (ACB), the magnetic nanoparticle's magnetization response under an oscillating magnetic field, which is applied through an excitation coil, is detected with a balanced detection coil system. Results We built a Multi-Channel ACB system (MC-ACB) containing nineteen pick-up coils and obtained 2D quantitative images of magnetic nanoparticle distributions by solving an inverse problem. We reconstructed the magnetic nanoparticles spatial distributions in a field of view of 14 × 14 cm2 with a spatial resolution of 2.0 cm and sensitivity in the milligram scale. A correlation coefficient between quantitative reconstructed and nominal magnetic nanoparticle distributions above 0.6 was found for all measurements. Conclusion Besides other interesting features such as sufficient large field of view dimension for mice and rat studies, portability, and the ability to assess the quantitative magnetic nanoparticles distributions in real-time, the MC-ACB system is a promising tool for quantitative imaging of magnetic nanoparticles distributions in real-time, offering an affordable setup for easy access in clinical or laboratory environments.
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Affiliation(s)
- Guilherme Soares
- Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, 10587, Berlin, Germany. .,Biosciences Institute of Botucatu, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil.
| | - Leonardo Pinto
- Biosciences Institute of Botucatu, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil
| | - Maik Liebl
- Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, 10587, Berlin, Germany
| | - Gabriel Biasotti
- Biosciences Institute of Botucatu, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil
| | - Andre Prospero
- Biosciences Institute of Botucatu, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil
| | - Erick Stoppa
- Biosciences Institute of Botucatu, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil
| | - Andris Bakuzis
- Institute of Physics, Federal University of Goiás, Goiânia, 74690-900, Brazil
| | - Oswaldo Baffa
- Faculty of Philosophy, Sciences and Letters at Ribeirão Preto, University of São Paulo, Ribeirão Preto, Sao Paulo, 14040-900, Brazil
| | - Frank Wiekhorst
- Physikalisch-Technische Bundesanstalt, Abbestraße 2-12, 10587, Berlin, Germany
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Sena EMAB, Silva DVL, Américo MF, Nascimento JWG, Miranda JRA, Corá LA. GASTROINTESTINAL MOTILITY IN ELDERLY PATIENTS WITH WELL-CONTROLLED TYPE 2 DIABETES MELLITUS. ARQUIVOS DE GASTROENTEROLOGIA 2022; 59:231-237. [PMID: 35830034 DOI: 10.1590/s0004-2803.202202000-42] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/10/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Gastrointestinal (GI) motility disorders in type 2 diabetes mellitus (T2DM) are common. However, the endpoints in well-controlled T2DM in elderly patients are barely understood. OBJECTIVE To evaluate GI transit and gastric myoelectric activity in elderly patients with T2DM who were undergoing treatment with metformin and to compare them with non-diabetic healthy controls. METHODS A total of thirty participants were enrolled in this study: young non-diabetic (n=10), elderly non-diabetic controls (n=10), and patients with T2DM managed with metformin (n=10). After fasting overnight, the participants ingested a standard meal and magnetic markers for non-invasive monitoring of GI transit and gastric contractility using the alternating current biosusceptometry and electrogastrography techniques. RESULTS Mean gastric emptying time, mean colon arrival time, and mean intestinal transit time were determined. There were no significant differences between the groups and in the parameters evaluated (P>0.05). The frequency and amplitude of gastric myoelectric activity were not different between groups; however, abnormal rhythmic index and the half-bandwidth were slightly higher for both elderly diabetic and non-diabetic groups compared with the young adults (P<0.01 and P<0.05, respectively). CONCLUSION Our study showed unaltered gastric emptying and intestinal transit in T2DM patients with good glycemic control, and suggest changes in the gastric electrical activity can be a part of aging.
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Affiliation(s)
- Erika M A B Sena
- Universidade Federal de Alagoas, Hospital Universitário Professor Alberto Antunes, Maceió, AL, Brasil
| | - Dianna V L Silva
- Universidade Estadual de Ciências da Saúde de Alagoas, Centro de Ciências Integradoras, Maceió, AL, Brasil
| | - Madileine F Américo
- Universidade Federal do Mato Grosso, Instituto de Ciências Biológicas e da Saúde, Barra do Garças, MT, Brasil
| | - Jhony W G Nascimento
- Universidade Federal de Alagoas, Rede Nordeste de Biotecnologia, Maceió, AL, Brasil
| | - José R A Miranda
- Universidade Estadual Paulista, Departamento de Física e Biofísica, Botucatu, SP, Brasil
| | - Luciana A Corá
- Universidade Estadual de Ciências da Saúde de Alagoas, Centro de Ciências Integradoras, Maceió, AL, Brasil
- Universidade Federal de Alagoas, Rede Nordeste de Biotecnologia, Maceió, AL, Brasil
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Bezerra AT, Pinto LA, Rodrigues DS, Bittencourt GN, Mancera PFDA, Miranda JRDA. Classification of gastric emptying and orocaecal transit through artificial neural networks. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2021; 18:9511-9524. [PMID: 34814356 DOI: 10.3934/mbe.2021467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Classical quantification of gastric emptying (GE) and orocaecal transit (OCT) based on half-life time T$ _{50} $, mean gastric emptying time (MGET), orocaecal transit time (OCTT) or mean caecum arrival time (MCAT) can lead to misconceptions when analyzing irregularly or noisy data. We show that this is the case for gastrointestinal transit of control and of diabetic rats. Addressing this limitation, we present an artificial neural network (ANN) as an alternative tool capable of discriminating between control and diabetic rats through GE and OCT analysis. Our data were obtained via biological experiments using the alternate current biosusceptometry (ACB) method. The GE results are quantified by T$ _{50} $ and MGET, while the OCT is quantified by OCTT and MCAT. Other than these classical metrics, we employ a supervised training to classify between control and diabetes groups, accessing sensitivity, specificity, $ f_1 $ score, and AUROC from the ANN. For GE, the ANN sensitivity is 88%, its specificity is 83%, and its $ f_1 $ score is 88%. For OCT, the ANN sensitivity is 100%, its specificity is 75%, and its $ f_1 $ score is 85%. The area under the receiver operator curve (AUROC) from both GE and OCT data is about 0.9 in both training and validation, while the AUCs for classical metrics are 0.8 or less. These results show that the supervised training and the binary classification of the ANN was successful. Classical metrics based on statistical moments and ROC curve analyses led to contradictions, but our ANN performs as a reliable tool to evaluate the complete profile of the curves, leading to a classification of similar curves that are barely distinguished using statistical moments or ROC curves. The reported ANN provides an alert that the use of classical metrics can lead to physiological misunderstandings in gastrointestinal transit processes. This ANN capability of discriminating diseases in GE and OCT processes can be further explored and tested in other applications.
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Affiliation(s)
- Anibal Thiago Bezerra
- Institute of Exact Sciences, Federal University of Alfenas-MG (UNIFAL-MG), Alfenas-MG 37133-840, Brazil
| | - Leonardo Antonio Pinto
- Institute of Biosciences, São Paulo State University (UNESP), Botucatu-SP 18618-689, Brazil
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2D Quantitative Imaging of Magnetic Nanoparticles by an AC Biosusceptometry Based Scanning Approach and Inverse Problem. SENSORS 2021; 21:s21217063. [PMID: 34770373 PMCID: PMC8587841 DOI: 10.3390/s21217063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 01/08/2023]
Abstract
The use of magnetic nanoparticles (MNPs) in biomedical applications requires the quantitative knowledge of their quantitative distribution within the body. AC Biosusceptometry (ACB) is a biomagnetic technique recently employed to detect MNPs in vivo by measuring the MNPs response when exposed to an alternate magnetic field. The ACB technique presents some interesting characteristics: non-invasiveness, low operational cost, high portability, and no need for magnetic shielding. ACB conventional methods until now provided only qualitative information about the MNPs’ mapping in small animals. We present a theoretical model and experimentally demonstrate the feasibility of ACB reconstructing 2D quantitative images of MNPs’ distributions. We employed an ACB single-channel scanning approach, measuring at 361 sensor positions, to reconstruct MNPs’ spatial distributions. For this, we established a discrete forward problem and solved the ACB system’s inverse problem. Thus, we were able to determine the positions and quantities of MNPs in a field of view of 5×5×1 cm3 with good precision and accuracy. The results show the ACB system’s capabilities to reconstruct the quantitative spatial distribution of MNPs with a spatial resolution better than 1 cm, and a sensitivity of 1.17 mg of MNPs fixed in gypsum. These results show the system’s potential for biomedical application of MNPs in several studies, for example, electrochemical-functionalized MNPs for cancer cell targeting, quantitative sensing, and possibly in vivo imaging.
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Prospero AG, Buranello LP, Fernandes CA, Dos Santos LD, Soares G, C Rossini B, Zufelato N, Bakuzis AF, de Mattos Fontes MR, de Arruda Miranda JR. Corona protein impacts on alternating current biosusceptometry signal and circulation times of differently coated MnFe 2O 4 nanoparticles. Nanomedicine (Lond) 2021; 16:2189-2206. [PMID: 34533056 DOI: 10.2217/nnm-2021-0195] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Background: We evaluated the impacts of corona protein (CP) formation on the alternating current biosusceptometry (ACB) signal intensity and in vivo circulation times of three differently coated magnetic nanoparticles (MNP): bare, citrate-coated and bovine serum albumin-coated MNPs. Methods: We employed the ACB system, gel electrophoresis and mass spectrometry analysis. Results: Higher CP formation led to a greater reduction in the in vitro ACB signal intensity and circulation time. We found fewer proteins forming the CP for the bovine serum albumin-coated MNPs, which presented the highest circulation time in vivo among the MNPs studied. Conclusion: These data showed better biocompatibility, stability and magnetic signal uniformity in biological media for bovine serum albumin-coated MNPs than for citrate-coated MNPs and bare MNPs.
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Affiliation(s)
- Andre Gonçalves Prospero
- Department of Biophysics and Pharmacology, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil
| | - Lais Pereira Buranello
- Department of Biophysics and Pharmacology, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil
| | - Carlos Ah Fernandes
- Department of Biophysics and Pharmacology, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil.,Museum National d'Histoire Naturelle, Institut de Minéralogie, Physique des Matériaux et Cosmochimie, IMPMC, Sorbonne Université, UMR 7590, CNRS, Paris, France
| | - Lucilene Delazari Dos Santos
- Graduate Program in Tropical Diseases, Botucatu Medical School (FMB), São Paulo State University (UNESP), Botucatu, São Paulo, 18618-687, Brazil.,Biotechnology Institute, São Paulo State University, Botucatu, São Paulo, 18607-440, Brazil
| | - Guilherme Soares
- Department of Biophysics and Pharmacology, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil
| | - Bruno C Rossini
- Biotechnology Institute, São Paulo State University, Botucatu, São Paulo, 18607-440, Brazil
| | - Nícholas Zufelato
- Institute of Physics and CNanoMed, Federal University of Goiás, Goiânia, 74690-900, Brazil
| | | | - Marcos R de Mattos Fontes
- Department of Biophysics and Pharmacology, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil
| | - José R de Arruda Miranda
- Department of Biophysics and Pharmacology, São Paulo State University, Botucatu, São Paulo, 18618-689, Brazil
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Pinto L, Soares G, Próspero A, Stoppa E, Biasotti G, Paixão F, Santos A, Oliveira R, Miranda J. An easy and low-cost biomagnetic methodology to study regional gastrointestinal transit in rats. ACTA ACUST UNITED AC 2021; 66:405-412. [PMID: 33544465 DOI: 10.1515/bmt-2020-0202] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 01/19/2021] [Indexed: 12/12/2022]
Abstract
The identification of gastrointestinal (GI) motility disorders requires the evaluation of regional GI transit, and the development of alternative methodologies in animals has a significant impact on translational approaches. Therefore, the purpose of this study was to validate an easy and low-cost methodology (alternate current biosusceptometry - ACB) for the assessment of regional GI transit in rats through images. Rats were fed a test meal containing magnetic tracer and phenol red, and GI segments (stomach, proximal, medial and distal small intestine, and cecum) were collected to assess tracer's retention at distinct times after ingestion (0, 60, 120, 240, and 360 min). Images were obtained by scanning the segments, and phenol red concentration was determined by the sample's absorbance. The temporal retention profile, geometric center, gastric emptying, and cecum arrival were evaluated. The correlation coefficient between methods was 0.802, and the temporal retention of each segment was successfully assessed. GI parameters yielded comparable results between methods, and ACB images presented advantages as the possibility to visualize intrasegmental tracer distribution and the automated scan of the segments. The imaging approach provided a reliable assessment of several parameters simultaneously and may serve as an accurate and sensitive approach for regional GI research in rats.
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Affiliation(s)
- Leonardo Pinto
- Department of Biophysics and Pharmacology, São Paulo State University, Biosciences Institute of Botucatu, Botucatu, Brazil
| | - Guilherme Soares
- Department of Biophysics and Pharmacology, São Paulo State University, Biosciences Institute of Botucatu, Botucatu, Brazil
| | - André Próspero
- Department of Biophysics and Pharmacology, São Paulo State University, Biosciences Institute of Botucatu, Botucatu, Brazil
| | - Erick Stoppa
- Department of Biophysics and Pharmacology, São Paulo State University, Biosciences Institute of Botucatu, Botucatu, Brazil
| | - Gabriel Biasotti
- Department of Biophysics and Pharmacology, São Paulo State University, Biosciences Institute of Botucatu, Botucatu, Brazil
| | - Fabiano Paixão
- Science and Technology Institute, Federal University of São Paulo, São José dos Campos, Brazil
| | - Armênio Santos
- Department of Physiology and Pharmacology, Federal University of Ceará, Fortaleza, Brazil
| | - Ricardo Oliveira
- Ribeirão Preto Medical School, São Paulo University, Ribeirão Preto, Brazil
| | - José Miranda
- Department of Biophysics and Pharmacology, São Paulo State University, Biosciences Institute of Botucatu, Botucatu, Brazil
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Próspero AG, Soares GA, Moretto GM, Quini CC, Bakuzis AF, de Arruda Miranda JR. Dynamic cerebral perfusion parameters and magnetic nanoparticle accumulation assessed by AC biosusceptometry. BIOMED ENG-BIOMED TE 2020; 65:343-351. [PMID: 31714878 DOI: 10.1515/bmt-2019-0089] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 08/30/2019] [Indexed: 01/25/2023]
Abstract
Cerebral blood flow (CBF) assessment is mainly performed by scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI). New approaches to assess the CBF through the passage of magnetic nanoparticles (MNPs) to blood-brain barrier (BBB) are convenient to help decrease the use of ionizing radiation and unleash the required MRI schedule in clinics. The development of nanomedicine and new biomedical devices, such as the magnetic particle imaging (MPI), enabled new approaches to study dynamic brain blood flow. In this paper, we employed MNPs and the alternating current biosusceptometry (ACB) to study the brain perfusion. We utilized the mannitol, before the MNPs, injection to modulate the BBB permeability and study its effects on the circulation time of the MNPs in the brain of rats. Also, we characterized a new ACB sensor to increase the systems' applicability to study the MNPs' accumulation, especially in the animals' brain. Our data showed that the injection of mannitol increased the circulation time of MNPs in the brain. Also, the mannitol increased the accumulation of MNPs in the brain. This paper suggests the use of the ACB as a tool to study brain perfusion and accumulation of MNPs in studies of new nano agents focused on the brain diagnostics and treatment.
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Affiliation(s)
- André Gonçalves Próspero
- Department of Physics and Biophysics, UNESP, São Paulo State University, Biosciences Institute of Botucatu, Prof. Antonio Celso Wagner Zanin Street, 18618-689 Botucatu, Brazil
| | - Guilherme Augusto Soares
- Department of Physics and Biophysics, UNESP, São Paulo State University, Biosciences Institute of Botucatu, Botucatu, Brazil
| | - Gustavo Morlin Moretto
- Department of Physics and Biophysics, UNESP, São Paulo State University, Biosciences Institute of Botucatu, Botucatu, Brazil
| | - Caio C Quini
- Department of Physics and Biophysics, UNESP, São Paulo State University, Biosciences Institute of Botucatu, Botucatu, Brazil
| | | | - José Ricardo de Arruda Miranda
- Department of Physics and Biophysics, UNESP, São Paulo State University, Biosciences Institute of Botucatu, Botucatu, Brazil
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Nunes ADC, Gomes-Silva LA, Zufelato N, Prospero AG, Quini CC, Matos RVR, Miranda JRA, Bakuzis AF, Castro CH. Albumin Coating Prevents Cardiac Effect of the Magnetic Nanoparticles. IEEE Trans Nanobioscience 2019; 18:640-650. [PMID: 31398127 DOI: 10.1109/tnb.2019.2931962] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We have showed that surface layer can determine cardiac effects of the magnetic nanoparticles (MNPs). Considering the high binding capacity of albumin and low side-effects, the aim of this study was to evaluate the influence of albumin coating on the cardiovascular effects of two manganese ferrite-based MNPs: citrate-coated and bare MNPs. Isolated rat hearts were perfused with citrate-coated magnetic nanoparticles (CiMNPs), citrate albumin-coated magnetic nanoparticles (CiAlbMNPs), bare magnetic nanoparticles (BaMNPs), and albumin-coated magnetic nanoparticles (AlbMNPs). CiMNPs induce a transient decrease in the left ventricular end-systolic pressure, +dP/dt and -dP/dt. These effects were not worsened by albumin coating. BaMNPs significantly increased the left ventricular end-diastolic pressure and perfusion pressure and decreased the +dP/dt and -dP/dt. These effects were completely absent in hearts perfused with AlbMNPs. None of the MNPs changed heart rate or arterial blood pressure in conscious rats. Magnetic signals in isolated hearts perfused with BaMNPs were significantly higher than AlbMNPs perfused hearts. However, the magnetic signal in heart tissue was similar when the MNPs were infused in conscious rats. These data indicate that albumin-coated can reduce cardiovascular effects of MNPs. These findings suggest a protective effect of albumin surface in MNPs, favoring its future therapeutic applications.
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Real-time liver uptake and biodistribution of magnetic nanoparticles determined by AC biosusceptometry. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2017; 13:1519-1529. [DOI: 10.1016/j.nano.2017.02.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/30/2017] [Accepted: 02/05/2017] [Indexed: 01/05/2023]
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Bruno AC, Sampaio DRT, Pavan TZ, Baffa O, Carneiro AAO. A hybrid transducer to evaluate stomach emptying by ultrasound and susceptometric measurements: an in vivo feasibility study. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2015; 62:1288-1294. [PMID: 26168175 DOI: 10.1109/tuffc.2014.006950] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Gastric emptying reflects a diversity of important physiological functions. Alternating current biosusceptometry (ACB) is an inexpensive, radiation-free, and minimally invasive method to evaluate gastric emptying, but its response depends on the spatial distribution of the magnetized material and does not provide precise anatomical information. The hybrid transducer, which combines ACB and an ultrasound probe, is an alternative to improve susceptometry measurements, namely the spatial localization of the magnetized source. In this study, initial stomach emptying, in rats, was monitored with the aid of the hybrid transducer. Yogurt mixed with ferrite particles was injected into the rat's stomach. The hybrid transducer was placed on the rat's abdomen during experiments, and the susceptometry signal and magnetomotive ultrasound (MMUS) images were saved and postprocessed. MMUS highlighted the movement of magnetic particles due to magnetic force from ACB excitation coils, and showed the rat's stomach location. In this feasibility study, we monitored the stomach emptying of 4 rats for 20 min. The mean relative ACB signal decayed by 4.6 ± 0.1%, and the mean relative area of MMUS images decreased by 4.5 ± 0.2%, after 20 min postingestion of the magnetic meal due to stomach emptying. In a second experiment, 3-D MMUS images from axial sequences were obtained by spatially translating the hybrid transducer, providing details of the stomach wall, which may enable minimally invasive detection of abnormalities. In conclusion, the MMUS image increased ACB spatial resolution and furnished additional anatomical information.
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Bruno AC, Pavan TZ, Baffa O, Carneiro AAO. A hybrid transducer to magnetically and ultrasonically evaluate magnetic fluids. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2013; 60:2004-2012. [PMID: 24658731 DOI: 10.1109/tuffc.2013.2785] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Ultrasound, magnetic fields, and optical techniques have been explored for clinical diagnosis and therapy. However, these techniques have limitations. In this study, we constructed and characterized a transducer to magnetically and ultrasonically investigate samples labeled with magnetic particles. The transducer is a hybrid system consisting of an ac biosusceptometer (ACB) and an ultrasonic transducer. The basic operation principle consisted of measuring the magnetization and microvibrations of ferromagnetic particles (37 and 70 μm) mixed in yogurt and excited by an external alternating magnetic field generated by the ACB's excitation coils. The vibration of the ferromagnetic particles was measured in phantoms using a Doppler ultrasonic transducer; we verified the sensitivity to detecting the vibrations at low concentrations of ferromagnetic material (~1%). The responses of the susceptometer and Doppler ultrasound linearly depended on the voltage level applied to the magnetizing coils at low ferromagnetic particle concentrations (⩽ 5%). We also conducted a repeatability test on the prototype, which indicated a deviation of 0.94% and 0.25% in the Doppler and susceptometric measurements, respectively. We can conclude that the hybrid transducer technique has potential clinical applications.
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Ferrari PC, Grossklauss DBBDS, Alvarez M, Paixão FC, Andreis U, Crispim AG, Castro ADD, Evangelista RC, Miranda JRDA. A novel automated alternating current biosusceptometry method to characterization of controlled-release magnetic floating tablets of metronidazole. Drug Dev Ind Pharm 2013; 40:1123-31. [DOI: 10.3109/03639045.2013.809537] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Teixeira M, Magalhães I, Galvão P, Souza G, Miranda J, Oliveira R, Corá L. Assessment of Gastrointestinal Motility in Renal Transplant Recipients by Alternate Current Biosusceptometry. Transplant Proc 2012; 44:2384-7. [DOI: 10.1016/j.transproceed.2012.07.048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Weitschies W, Wilson CG. In vivo imaging of drug delivery systems in the gastrointestinal tract. Int J Pharm 2011; 417:216-26. [DOI: 10.1016/j.ijpharm.2011.07.031] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 07/19/2011] [Accepted: 07/19/2011] [Indexed: 11/17/2022]
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Paixao FC, Quini CC, Baffa O, Miranda JRDA. A novel device with 36 channels for imaging and signal acquisition of the gastrointestinal tract based on AC biosusceptometry. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2010:6457-60. [PMID: 21096717 DOI: 10.1109/iembs.2010.5627341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The alternate current biosusceptometry (ACB) is a biomagnetic technique used to study some physiological parameters associated with gastrointestinal (GI) tract. For this purpose it applies an AC magnetic field and measures the response originating from magnetic marks or tracers. This paper presents an equipment based on the ACB which uses anisotropic magnetoresistive (AMR) sensors and an inexpensive electronic support. The ACB-AMR developed consists of a square array of 6×6 sensors arranged in a first-order gradiometer configuration with one reference sensor. The equipment was applied to capture magnetic images of different phantoms and to acquire gastric contraction activity of healthy rats. The results show a reasonable sensitivity and spatial-temporal resolution, so that it may be applied for imaging of phantoms and signal acquisition of the GI tract of small animals.
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Affiliation(s)
- Fabiano C Paixao
- Faculdade de Física, Pontifical Catholic University of Rio Grande do Sul - PUCRS, Av. Ipiranga, 6681 - Partenon, 90619-900, Porto Alegre-RS, Brazil.
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Corá LA, Américo MF, Oliveira RB, Serra CHR, Baffa O, Evangelista RC, Oliveira GF, Miranda JRA. Biomagnetic Methods: Technologies Applied to Pharmaceutical Research. Pharm Res 2010; 28:438-55. [DOI: 10.1007/s11095-010-0285-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 09/14/2010] [Indexed: 02/06/2023]
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Bruno AC, Baffa O, Carneiro AO. Hybrid system for magnetic and acoustic measurement. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2009:761-4. [PMID: 19964487 DOI: 10.1109/iembs.2009.5334067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In order to improve the spatial resolution of Biosusceptometry of Alternate Current (BAC), we are suggesting the coupling of a Doppler ultrasonic transducer with the BAC system. The Doppler transducer obtains information from the vibration of ferromagnetic particles immersed in a visco-elastic medium when it is excited by an alternating magnetic field. In this case, the same magnetic particles used as contrast for susceptometric measurement also will work as contrast for the Doppler measurement. In this work, we present the characterization of the hybrid system for susceptometric and acoustic measurements simultaneously. It was observed that the susceptometric and Doppler ultrasound signal have the same profile and maximum amplitude for frequency of magnetizing field about 200 Hz. When using ferrite particles as magnetic contrast mixed with yogurt as based material, the susceptometric and Doppler measurement have sensitivity for concentration of particles as low as 1%. The sensitivity of the Doppler is dependent of the gradient of magnetic field over the sample. In this work, the magnetic field 5 cm far from the face of the transducer was 70 microT/volts.
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Affiliation(s)
- A C Bruno
- Departamento de Física e Matemática, Universidade de São Paulo, Brazil.
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18
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Pharmaceutical applications of AC biosusceptometry. Eur J Pharm Biopharm 2009; 74:67-77. [PMID: 19482083 DOI: 10.1016/j.ejpb.2009.05.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 05/19/2009] [Accepted: 05/22/2009] [Indexed: 12/28/2022]
Abstract
AC Biosusceptometry offers an alternative to investigate noninvasively and without ionizing radiation the behavior of solid dosage forms in vitro and in the human gastrointestinal tract. This versatility allowed applying this technique in a wide field ranging from characterization of the disintegration process to elucidation of how the physiological parameters can interfere with pharmaceutical processes. It is increasingly important to understand how oral solid dosage forms behave in the human gastrointestinal tract. Once labelled, magnetic dosage forms provide an excellent opportunity to investigate complexes' interactions between dosage form and gastrointestinal physiology. In this paper, basic principles of this biomagnetic instrumentation and of the quantification based on magnetic images are reviewed. Also will be presented are some of the most recent applications of AC Biosusceptometry in the pharmaceutical research including oesophageal transit, gastric emptying and transit time of multiparticulate dosage forms, hydrophilic matrices and disintegration of tablets.
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19
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Machado WM, Miranda JRA, Morceli J, Padovani CR. The small bowel flora in individuals with cecoileal reflux. ARQUIVOS DE GASTROENTEROLOGIA 2008; 45:212-8. [DOI: 10.1590/s0004-28032008000300009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Accepted: 10/09/2007] [Indexed: 11/21/2022]
Abstract
BACKGROUND: The observation of cecoileal reflux to barium enema is not rare; however, its causes and consequences have not been widely investigated. Considering that ileocecal junction exerts a function as barrier to invasion of bacteria from colon to small bowel, it seems interesting to study the intestinal microflora in subjects carrying cecoileal reflux. AIMS: This study aims at evaluating the ileal flora in individuals with cecoileal reflux. METHODS: A group of 36 subjects comprising 30 females and 6 males with a mean age of 54 years was assessed. Twenty-five individuals with cecoileal reflux and 11 without cecoileal reflux were submitted to small intestine contamination evaluation through the breath test with lactulose-H2 and measurement of the orocecal transit time by means of alternate current biosusceptometry. Small intestine bacterial overgrowth was characterized by orocecal transit time-H2 shortening. RESULTS: Comparison of basal H2, orocecal transit time-H2 and orocecal transit time-alternate current biosusceptometry measurements did not statistically differ between the groups with and without cecoileal reflux. Orocecal transit time-H2 was significantly smaller than orocecal transit time-alternate current biosusceptometry, particularly in individuals with cecoileal reflux. A significant correlation between the two methods was observed only in relation to control, not existing in relation to cecoileal reflux group. CONCLUSIONS: Smaller orocecal transit time-H2 and the loss of correlation with orocecal transit time-alternate current biosusceptometry observed in the individuals with cecoileal reflux suggest a differentiated behavior for such group relative to control, which could be associated with small intestine bacterial overgrowth.
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Paixão FC, Silva FM, Miranda JRDA, Baffa O. Magnetoresistive sensors in a new biomagnetic instrumentation for applications in gastroenterology. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2008; 2007:2948-51. [PMID: 18002613 DOI: 10.1109/iembs.2007.4352947] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Anisotropic Magnetoresistive (AMR) sensors shows a new possibility to detect magnetic fields produced by magnetic particles present in the gastrointestinal (GI) tract. A system that uses excitation and detection of magnetic field was developed using AMR sensor. A magnetic flux concentrator was also studied to increase the sensitivity of AMR in this work.
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Affiliation(s)
- Fabiano C Paixão
- Departamento de Física e Biofísica, IBB - Universidade Estadual Paulista (UNESP), Distrito de Rubião Júnior, Botucatu-SP, Brazil
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21
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Paixão FC, de Moraes R, Stelzer M, Corá LA, Américo MF, Andreis U, Oliveira RB, Baffa O, de A Miranda JR. A novel biomagnetic instrumentation with four magnetoresistive sensors to evaluate gastric motility. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2008; 2007:2215-8. [PMID: 18002430 DOI: 10.1109/iembs.2007.4352764] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A novel instrumentation using anisotropic magnetoresistive (AMR) sensors associated with magnetic coils excitation was developed to evaluate gastrointestinal tract motility parameters. The susceptometer has four sensors that were used to measure the gastric activity contractions (GAC) in anaesthetized dogs, its performance was evaluated by manometry with good results.
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Affiliation(s)
- Fabiano C Paixão
- Departamento de Física e Biofísica, IBB - Universidade Estadual Paulista, Distrito de Rubião Júnior, S/N, 18.618-000, Botucatu-SP, Brazil
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22
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Baffa O, Cora L, Americo M, Fonseca P, Oliveira R, A Miranda J. Magnetic images of pharmaceutical dosage forms in the human gastrointestinal tract. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2005:7254-7. [PMID: 17281954 DOI: 10.1109/iembs.2005.1616185] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Oral administration with solid dosage forms is a common route in the drug therapy widely used. The drug release by the disintegration process occurs in several gastrointestinal tract (GIT) regions. AC Biosusceptometry (ACB) was originally proposal to characterize the disintegration process of tablets in vitro and in the human stomach, through changes in magnetic signals. The aim of this work was to employ a multisensor ACB system to monitoring magnetic tablets and capsules in the human GIT and to obtain the magnetic images of the disintegration process. The ACB showed accuracy to quantify the gastric residence time, the intestinal transit time and the magnetic images allowed to visualize the disintegration of magnetic formulations in the GIT. The ACB is a non-invasive, radiation free technique, completely safe and harmless to the volunteers and had demonstrated potential to evaluate pharmaceutical dosage forms in the human gastrointestinal tract.
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Affiliation(s)
- O Baffa
- Department of Physics and Mathematics, FFCLRP, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
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23
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Romeiro FG, Corá LA, de Andreis U, Américo MF, Oliveira RB, Baffa O, Miranda JRA. A novel biomagnetic approach to study caecocolonic motility in humans. Neurogastroenterol Motil 2006; 18:1078-83. [PMID: 17109691 DOI: 10.1111/j.1365-2982.2006.00838.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Motility patterns play a major role in human colonic functions; however, its physiological significance is poorly understood. Several studies have been introducing the Alternating Current Biosusceptometry (ACB) as a valuable tool in gastroenterology and pharmaceutical research. Using gold standard techniques, great effort has been made to validate ACB as a method for measuring gastrointestinal motility in humans and animals. The aim of this study was to evaluate caecocolonic motility and its response to a meal in healthy volunteers. The results showed a dominant frequency of 3.17 +/- 0.13 cycles per minute (mean +/- SD) that remained unchanged even after a standardized meal (P > 0.01). The colonic response to a meal was recorded as a considerable increase in amplitude, reflected by motility index (P < 0.01) and was observed for all the volunteers. The caecocolonic motility could be assessed by the ACB providing new insights into physiological patterns of motility. Moreover, the method is non-invasive, radiation-free, cost-effective and independent of bowel preparation.
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Affiliation(s)
- F G Romeiro
- Departamento de Clínica Médica, FMB, Universidade Estadual Paulista - UNESP, Botucatu, São Paulo, Brazil
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Corá LA, Romeiro FG, Paixão FC, Américo MF, Oliveira RB, Baffa O, Miranda JRA. Enteric Coated Magnetic HPMC Capsules Evaluated in Human Gastrointestinal Tract by AC Biosusceptometry. Pharm Res 2006; 23:1809-16. [PMID: 16858651 DOI: 10.1007/s11095-006-9035-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Accepted: 04/11/2006] [Indexed: 10/24/2022]
Abstract
PURPOSE To employ the AC Biosusceptometry (ACB) technique to evaluate in vitro and in vivo characteristics of enteric coated magnetic hydroxypropyl methylcellulose (HPMC) capsules and to image the disintegration process. MATERIALS AND METHODS HPMC capsules filled with ferrite (MnFe2O4) and coated with Eudragit were evaluated using USP XXII method and administered to fasted volunteers. Single and multisensor ACB systems were used to characterize the gastrointestinal (GI) motility and to determine gastric residence time (GRT), small intestinal transit time (SITT) and orocaecal transit time (OCTT). Mean disintegration time (t50) was quantified from 50% increase of pixels in the imaging area. RESULTS In vitro and in vivo performance of the magnetic HPMC capsules as well as the disintegration process were monitored using ACB systems. The mean disintegration time (t50) calculated for in vitro was 25+/-5 min and for in vivo was 13+/-5 min. In vivo also were determined mean values for GRT (55+/-19 min), SITT (185+/-82 min) and OCTT (240+/-88 min). CONCLUSIONS AC Biosusceptometry is a non-invasive technique originally proposed to monitoring pharmaceutical dosage forms orally administered and to image the disintegration process.
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Affiliation(s)
- Luciana A Corá
- Departamento de Física e Biofísica, IBB, Universidade Estadual Paulista-UNESP, Distrito Rubião Jr, s/n, CXP 510, CEP 18618-000, Botucatu, São Paulo, Brazil
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Corá LA, Romeiro FG, Américo MF, Oliveira RB, Baffa O, Stelzer M, Miranda JRDA. Gastrointestinal transit and disintegration of enteric coated magnetic tablets assessed by ac biosusceptometry. Eur J Pharm Sci 2006; 27:1-8. [PMID: 16188432 DOI: 10.1016/j.ejps.2005.08.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Revised: 01/11/2005] [Accepted: 08/04/2005] [Indexed: 11/20/2022]
Abstract
The oral administration is a common route in the drug therapy and the solid pharmaceutical forms are widely used. Although much about the performance of these formulations can be learned from in vitro studies using conventional methods, evaluation in vivo is essential in product development. The knowledge of the gastrointestinal transit and how the physiological variables can interfere with the disintegration and drug absorption is a prerequisite for development of dosage forms. The aim of this work was to employing the ac biosusceptometry (ACB) to monitoring magnetic tablets in the human gastrointestinal tract and to obtain the magnetic images of the disintegration process in the colonic region. The ac biosusceptometry showed accuracy in the quantification of the gastric residence time, the intestinal transit time and the disintegration time (DT) of the magnetic formulations in the human gastrointestinal tract. Moreover, ac biosusceptometry is a non-invasive technique, radiation-free and harmless to the volunteers, as well as an important research tool in the pharmaceutical, pharmacological and physiological investigations.
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Affiliation(s)
- Luciana A Corá
- Department of Physics and Biophysics, Biosciences Institute, IBB, Laboratório de Biomagnetismo, Universidade Estadual Paulista, CXP 510, Rua Botucatu, São Paulo CEP 18618-000, Brazil
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26
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Corá LA, Andreis U, Romeiro FG, Américo MF, Oliveira RB, Baffa O, Miranda JRA. Magnetic images of the disintegration process of tablets in the human stomach by ac biosusceptometry. Phys Med Biol 2005; 50:5523-34. [PMID: 16306649 DOI: 10.1088/0031-9155/50/23/007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Oral administration of solid dosage forms is usually preferred in drug therapy. Conventional imaging methods are essential tools to investigate the in vivo performance of these formulations. The non-invasive technique of ac biosusceptometry has been introduced as an alternative in studies focusing on gastrointestinal motility and, more recently, to evaluate the behaviour of magnetic tablets in vivo. The aim of this work was to employ a multisensor ac biosusceptometer system to obtain magnetic images of disintegration of tablets in vitro and in the human stomach. The results showed that the transition between the magnetic marker and the magnetic tracer characterized the onset of disintegration (t(50)) and occurred in a short time interval (1.1 +/- 0.4 min). The multisensor ac biosusceptometer was reliable to monitor and analyse the in vivo performance of magnetic tablets showing accuracy to quantify disintegration through the magnetic images and to characterize the profile of this process.
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Affiliation(s)
- L A Corá
- Departamento de Física e Biofísica, IBB, UNESP, Botucatu, SP, Brazil
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27
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Corá LA, Américo MF, Oliveira RB, Baffa O, Moraes R, Romeiro FG, Miranda JRA. Disintegration of magnetic tablets in human stomach evaluated by alternate current Biosusceptometry. Eur J Pharm Biopharm 2003; 56:413-20. [PMID: 14602185 DOI: 10.1016/s0939-6411(03)00136-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Oral administration is the most convenient route for drug therapy. The knowledge of the gastrointestinal transit and specific site for drug delivery is a prerequisite for development of dosage forms. The aim of this work was to demonstrate that is possible to monitor the disintegration process of film-coated magnetic tablets by multi-sensor alternate current Biosusceptometry (ACB) in vivo and in vitro. This method is based on the recording of signals produced by the magnetic tablet using a seven sensors array and signal-processing techniques. The disintegration was confirmed by signals analysis in healthy human volunteers' measurements and in vitro experiments. Results showed that ACB is efficient to characterize the disintegration of dosage forms in the stomach, being a research tool for the development of new pharmaceutical dosage forms.
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Affiliation(s)
- Luciana A Corá
- Department of Pharmacology, Biosciences Institute, UNESP, Botucatu-SP, Brazil
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Moraes R, Corá LA, Américo MF, Oliveira RB, Baffa O, Miranda JRA. Measurement of gastric contraction activity in dogs by means of AC biosusceptometry. Physiol Meas 2003; 24:337-45. [PMID: 12812419 DOI: 10.1088/0967-3334/24/2/309] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The mechanical nature of gastric contraction activity (GCA) plays an important role in gastrointestinal motility. The aim of this study was to detect GCA in anaesthetized dogs, using simultaneously the techniques of AC biosusceptometry (ACB) and manometry, analysing the characteristics of frequency and amplitude (motility index) of GCA, modified by drugs such as prostigmine and N-butyl-scopolamine. The ACB method is based on a differential transformer of magnetic flux and the magnetic tracer works as a changeable external nucleus. This magnetic tracer causes a modification in the magnetic flux, which is detected by the coils. The results obtained from the ACB showed a performance comparable to the manometry in measuring the modifications in the frequency and amplitude of the GCA. We concluded that this ACB technique, non-invasive and free of ionizing radiation, is an option for evaluating GCA and can be employed in future clinical studies.
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Affiliation(s)
- R Moraes
- Department of Physics and Biophysics, Laboratory of Biomag, Instituto de Biociências, Universidade Estadual Paulista, Unesp, PO Box 510, Botucatu, SP 18618-000, Brazil.
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Bradshaw LA, Ladipo JK, Staton DJ, Wikswo JP, Richards WO. The human vector magnetogastrogram and magnetoenterogram. IEEE Trans Biomed Eng 1999; 46:959-70. [PMID: 10431461 DOI: 10.1109/10.775406] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Electrical activity in the gastrointestinal system produces magnetic fields that may be measured with superconducting quantum interference device magnetometers. Although typical magnetometers have detection coils that measure a single component of the magnetic field, gastric and intestinal magnetic fields are vector quantities. We recorded gastric and intestinal magnetic fields from nine abdominal sections in nine normal human volunteers using a vector magnetometer that measures all three Cartesian components of the magnetic field vector. A vector projection technique was utilized to separate the magnetic field vectors corresponding to gastric and intestinal activity. The gastric magnetic field vector was oriented in a cephalad direction, consistent with previously observed data, and displayed oscillatory characteristics of gastric electrical activity (f = 3.03 +/- 0.18 cycles/min). Although the small bowel magnetic field vector showed no consistent orientation, the characteristic frequency gradient of the small bowel electrical activity was observed. Gastric and intestinal magnetic field vectors were oriented in different directions and were thus distinguished by the vector projection technique. The observed difference in direction of gastric and intestinal magnetic field vectors indicates that vector recordings dramatically increase the ability to separate physiological signal components from nonphysiological components and to distinguish between different physiological components.
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Affiliation(s)
- L A Bradshaw
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA.
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Daghastanli NA, Braga FJ, Oliveira RB, Baffa O. Oesophageal transit time evaluated by a biomagnetic method. Physiol Meas 1998; 19:413-20. [PMID: 9735892 DOI: 10.1088/0967-3334/19/3/010] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The aim of this work was to determine the oesophageal transit time (OTT) of a bolus using the biomagnetic technique and compare the results to those obtained by means of scintigraphy. For the biomagnetic evaluation, a test meal (yoghurt) uniformly labelled with 5 g of powder ferrite was swallowed in a single gulp by 19 normal volunteers in the upright position. One sensor (first order gradiometer) was placed at the furcula and a second one at the xiphoid process to detect the passage of the test meal and the magnetic signal output was recorded in a computer. The OTT was determined by plotting the voltage signal against time. The scintigraphic technique was used in the same volunteers: the test meal was labelled with less than 350 MBq of 99mTc-phytate and swallowed in the same way. The bolus transit was recorded at 4 frames s(-1) (100-120 frames acquisition) and the OTT was determined by drawing two regions of interest in the same areas as the sensors. The results were determined by plotting counts against time. The averages for OTTs were 3.8 +/- 0.8 s for the scintigraphic technique and 4.6 +/- 0.9 s for the biomagnetic technique. Although scintigraphic OTT was significantly shorter than magnetic OTT, there was a significant correlation between them. We conclude that the biomagnetic study may be used to evaluate OTT.
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Affiliation(s)
- N A Daghastanli
- Department of Physics and Mathematics-FFCLRP-USP, Ribeirão Preto, SP, Brazil.
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Miranda JR, Oliveira RB, Sousa PL, Braga FJ, Baffa O. A novel biomagnetic method to study gastric antral contractions. Phys Med Biol 1997; 42:1791-9. [PMID: 9308084 DOI: 10.1088/0031-9155/42/9/010] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A novel non-invasive method to study the motion associated with gastric antral contractions is discussed. The method is based on magnetic flux changes detected by an a.c. biosusceptometer, produced by a magnetic test meal within the stomach. Measurements are made at the surface of the torso and are easy to perform. Simultaneous measurements were made with electrogastrography and scintigraphy showing remarkable coincidence. The effect of a drug on the amplitude of antral contractions was also assayed with the new method.
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Affiliation(s)
- J R Miranda
- Departamento de Física e Matemática, FFCLRP-Universidade de São Paulo, Ribeirão Preto-SP, Brazil
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