RESUMO
BACKGROUND: Radiation necrosis in eloquent areas of the central nervous system (CNS) is one of the most serious forms of toxicity from radiation therapy. The occurrence of radiation necrosis in the CNS is described in a wide range of 3 months to 13 years after radiation therapy. The incidence of this complication covers a wide range of 3-47%. The potential advantage of proton therapy is the ability to reduce dose to normal tissue and escalate tumor dose. Proton beams enter and pass through the tissue with minimal dose deposition until they reach the end of their paths, where the peak of dose, known as the Bragg peak, occurs. Thereafter, a steep dose fall-off is evident. Such a precisely-distributed dose should reduce the toxicity of the treatment. PATIENT: A 23 year-old female patient underwent radical microsurgical resection of anaplastic ependymoma that originated from the floor of the fourth ventricle. The tumor was growing into the foramen magnum dorsally from the medulla oblongata. Taking into account the age of the patient, the localization of the tumor and the required dose of 60 Gy, proton therapy was chosen due to the lower risk of damage to the brain stem. Radiation therapy was performed using pencil beam scanning and one dorsal field. Following this course of treatment, radiation necrosis of the medulla oblongata and the upper cervical spinal cord occurred with fatal clinical impact on the patient. The article analyses possible causes of this complication and a review of the current literature is given. CONCLUSION: Despite the theoretical advantages of proton therapy, no clinical benefit in CNS tumors has yet been proven in comparison with modern methods of photon therapy. Proton therapy is accompanied by many uncertainties which can cause unpredictable complications, such as radiation necrosis at the edges of the target volume. Following proton therapy, there is not only a higher incidence of radiation necrosis but it occurs both sooner and to a higher degree. In cases of high anatomical complexity, the neurosurgeon should cooperate in the creation of the radiation treatment planning to ensure its optimization.Key words: brain tumors - ependymoma - radiation therapy - proton therapy - necrosis - radiation necrosis This work was partially supported by research project MH CZ - DRO (Faculty Hospital in Pilsen - FNPl, 00669806). The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 29. 6. 2017Accepted: 25. 7. 2017.
Assuntos
Neoplasias Encefálicas/radioterapia , Medula Cervical/patologia , Ependimoma/radioterapia , Terapia com Prótons/efeitos adversos , Lesões por Radiação/patologia , Neoplasias Encefálicas/cirurgia , Medula Cervical/efeitos da radiação , Ependimoma/cirurgia , Feminino , Quarto Ventrículo/patologia , Quarto Ventrículo/cirurgia , Humanos , Bulbo/patologia , Bulbo/efeitos da radiação , Necrose/etiologia , Adulto JovemRESUMO
PURPOSE: Infrared heat, a transient receptor potential vanilloid type-3 (TRPV3) sensitive stimulus, may have potential physiological effects beneficial to treating metabolic syndrome. MATERIALS AND METHODS: Obesity prone (OP) and obesity resistant (OR) rats were fed for seven days on a high-fat diet. Heat treated OP rats were exposed twice daily to infrared light for 20 min each, separated by 80 min of rest. Food intake, blood pressure, blood glucose, and body weight measurements were taken daily and compared between treated OP rats, untreated OP rats, and OR controls. The animals were perfused with 4% paraformaldehyde, and immunohistochemistry was performed on the coronal brainstem sections with polyclonal antibodies against TRPV3 and pro-opiomelanocortin (POMC). The positive-staining cells in the medulla nuclei were quantified using a microscope with reticule grid. RESULTS: Food intake, body weight, and mean arterial blood pressure (MAP) were higher in OP rats, a diet-induced metabolic syndrome model, accompanied by a reduced expression of POMC, an anorectic agent, in the hypoglossal nucleus (HN) and medial nucleus tractus solitarius (mNTS). Food intake in heat-treated OP rats was significantly decreased. POMC positive neuron count was increased in the HN and mNTS of OP rats following treatment. TRPV3 positive staining neurons were increased in the HN and mNTS of OP control rats and decreased following the heat treatments. CONCLUSION: Lowered POMC and heightened TRPV3 expressions in the HN and mNTS are involved in development of hyperphagia and obesity in OP rats. Exposure to infrared heat modifies TRPV3 and POMC expression in the brainstem, reducing food intake.
Assuntos
Ingestão de Alimentos/efeitos da radiação , Hipertermia Induzida , Raios Infravermelhos , Bulbo/metabolismo , Obesidade/fisiopatologia , Pró-Opiomelanocortina/biossíntese , Canais de Cátion TRPV/biossíntese , Animais , Dieta Hiperlipídica , Temperatura Alta , Hipertermia Induzida/métodos , Bulbo/efeitos da radiação , Síndrome Metabólica/fisiopatologia , RatosRESUMO
BACKGROUND AND OBJECTIVES: Mobile phone radiation and health concerns have been raised, especially following the enormous increase in the use of wireless mobile telephony throughout the world. The present study aims to investigate the effect of one hour daily exposure to electromagnetic radiation (EMR) with frequency of 900 Mz (SAR 1.165 w/kg, power density 0.02 mW/cm2) on the levels of amino acid neurotransmitters in the midbrain, cerebellum and medulla of adult and young male albino rats. MATERIALS AND METHODS: Adult and young rats were divided into two main groups (treated and control). The treated group of both adult and young rats was exposed to EMR for 1 hour daily. The other group of both adult and young animals was served as control. The determination of amino acid levels was carried out after 1 hour, 1 month, 2 months and 4 months of EMR exposure as well as after stopping radiation. RESULTS: Data of the present study showed a significant increase in both excitatory and inhibitory amino acids in the cerebellum of adult and young rats and midbrain of adult animals after 1 hour of EMR exposure. In the midbrain of adult animals, there was a significant increase in glycine level after 1 month followed by significant increase in GABA after 4 months. Young rats showed significant decreases in the midbrain excitatory amino acids. In the medulla, the equilibrium ratio percent (ER%) calculations showed a state of neurochemical inhibition after 4 months in case of adult animals, whereas in young animals, the neurochemical inhibitory state was observed after 1 month of exposure due to significant decrease in glutamate and aspartate levels. This state was converted to excitation after 4 months due to the increase in glutamate level. CONCLUSION: The present changes in amino acid concentrations may underlie the reported adverse effects of using mobile phones.
Assuntos
Aminoácidos/metabolismo , Encéfalo/efeitos da radiação , Telefone Celular , Campos Eletromagnéticos/efeitos adversos , Fatores Etários , Envelhecimento , Animais , Encéfalo/metabolismo , Cerebelo/metabolismo , Cerebelo/efeitos da radiação , Masculino , Bulbo/metabolismo , Bulbo/efeitos da radiação , Mesencéfalo/metabolismo , Mesencéfalo/efeitos da radiação , Ratos , Medição de Risco , Fatores de TempoRESUMO
The selection of control group is crucial, as the use of an inadequate group may strongly affect the results. In this study we examine the effect on contralateral tissue protein levels, in a model of unilateral UVB irradiation, as the contralateral side is commonly used as a control. Previous studies have shown that UVB irradiation increases immunoreactivity for inflammatory regulated neuropeptides. Unilateral UVB irradiation of rat hind paw was performed and corresponding contralateral spinal cord and dorsal root ganglia (DRG) were collected 2-96 h after and investigated for changes in galanin, substance P and c-fos immunoreactivity. Control tissue was collected from naïve rats. Measurement of skin blood flow from contralateral heel hind paws (Doppler), revealed no change compared to naïve rats. However, UVB irradiation caused a significant reduction in the contralateral proportion of galanin immunopositive DRG neurons, at all-time points, as well as an increase in the contralateral spinal cord dorsal horn, around the central canal and in the lateral spinal nucleus (2-48 h). The contralateral proportion of SP positive DRG neurons and dorsal horn immunoreactivity was unchanged, whereas the lateral spinal nucleus area showed increased immunoreactivity (48 h). UVB irradiation also induced a slight contralateral upregulation of c-fos in the dorsal horn/central canal area (24 and 48 h). In summary, unilateral UVB irradiation induced contralateral changes in inflammatory/nociceptive neuropeptides in spinal cord and afferent pathways involved in pain signaling already within 24 h, a time point when also ipsilateral neurochemical/physiological changes have been reported for rats and humans.
Assuntos
Galanina/imunologia , Neurônios/imunologia , Proteínas Proto-Oncogênicas c-fos/imunologia , Substância P/imunologia , Animais , Galanina/efeitos da radiação , Gânglios Espinais/imunologia , Gânglios Espinais/efeitos da radiação , Humanos , Bulbo/imunologia , Bulbo/efeitos da radiação , Neurônios/efeitos da radiação , Neuropeptídeos/genética , Dor/imunologia , Dor/patologia , Proteínas Proto-Oncogênicas c-fos/efeitos da radiação , Ratos , Nervo Isquiático/imunologia , Nervo Isquiático/efeitos da radiação , Medula Espinal/imunologia , Medula Espinal/efeitos da radiação , Corno Dorsal da Medula Espinal/metabolismo , Corno Dorsal da Medula Espinal/efeitos da radiação , Substância P/efeitos da radiação , Raios Ultravioleta/efeitos adversosRESUMO
BACKGROUND AND PURPOSE: Radiation (RT) dose to the central nervous system (CNS) has been implicated as a contributor to treatment-related fatigue in head and neck cancer (HNC) patients undergoing radiation therapy (RT). This study evaluates the association of RT dose to CNS structures with patient-reported (PRO) fatigue scores in a population of HNC patients. MATERIALS AND METHODS: At pre-RT (baseline), 6th week of RT, and 1-month post-RT time points, Multidimensional Fatigue Inventory (MFI-20) scores were prospectively obtained from 124 patients undergoing definitive treatment for HNC. Medulla, pons, midbrain, total brainstem, cerebellum, posterior fossa, and pituitary dosimetry were evaluated using summary statistics and dose-volume histograms, and associations with MFI-20 scores were analyzed. RESULTS: Maximum dose (Dmax) to the brainstem and medulla was significantly associated with MFI-20 scores at 6th week of RT and 1-month post-RT time points, after controlling for baseline scores (p<0.05). Each 1Gy increase in medulla Dmax resulted in an increase in total MFI-20 score over baseline of 0.30 (p=0.026), and 0.25 (p=0.037), at the 6th week of RT and 1-month post-RT, respectively. Each 1Gy increase in brainstem Dmax resulted in an increase in total MFI-20 score over baseline of 0.30 (p=0.027), and 0.25 (p=0.037) at the 6th week of RT, 1-month post-RT, respectively. Statistically significant associations were not found between dosimetry for the other CNS structures and MFI-20 scores. CONCLUSIONS: In this analysis of PRO fatigue scores from a population of patients undergoing definitive RT for HNC, maximum dose to the brainstem and medulla was associated with a significantly increased risk of acute patient fatigue.
Assuntos
Tronco Encefálico/efeitos da radiação , Carcinoma de Células Escamosas/radioterapia , Fadiga/etiologia , Neoplasias de Cabeça e Pescoço/radioterapia , Lesões por Radiação/etiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Bulbo/efeitos da radiação , Pessoa de Meia-Idade , Estudos Prospectivos , Qualidade de Vida , Carcinoma de Células Escamosas de Cabeça e PescoçoRESUMO
The rostral parvicellular reticular formation (rRFp) was explored electrophysiologically in urethane-chloralose anesthetized rats. Spontaneously-active neurons that exhibited a pulse-related activity were recorded and tested for their projections to the rostral ventrolateral medulla (RVLM). About one-third (10/29) of the rRFp neurons that exhibited a pulse-related activity were antidromically activated by RVLM stimulation with conduction velocities between 0.2-4.4m/s and fell within the B and C fibre range. A majority (8/10) of these neurons had a low (<10spikes/s) mean firing rate, whereas a small proportion (2/10) had a high (>15spikes/s) mean firing rate. These findings suggest a direct pathway from the rRFp to the RVLM and suggest that neurons projecting to the RVLM receive cardiac inputs and can modulate RVLM neuronal activity.
Assuntos
Coração/inervação , Bulbo/fisiologia , Vias Neurais/fisiologia , Neurônios/fisiologia , Formação Reticular/citologia , Potenciais de Ação/fisiologia , Potenciais de Ação/efeitos da radiação , Animais , Pressão Sanguínea/fisiologia , Estimulação Elétrica/métodos , Eletrocardiografia/métodos , Potenciais Evocados/fisiologia , Potenciais Evocados/efeitos da radiação , Bulbo/citologia , Bulbo/efeitos da radiação , Vias Neurais/efeitos dos fármacos , Ratos , Ratos Sprague-DawleyRESUMO
Muscle atonia is a central feature of adult REM sleep which has recently been demonstrated to be a component of sleep in rats as young as 2 days of age (P2). The neural generation of atonia, which depends on mesopontine and medullary structures, is not fully understood in adults and has never been described in infants. In the present experiments we used electrical stimulation in decerebrated pups to identify an inhibitory area within the medial medulla of P7-10 rats. Muscle tone inhibition was consistently found on or near the midline within the ventromedial medulla, dorsal to the inferior olive, in an area that includes the nucleus gigantocellularis, nucleus paramedianus, and raphe obscurus. Chemical infusions in the same region revealed inhibitory responses to quisqualic acid but not to carbachol or corticotropin-releasing factor. Next, extracellular recordings within the medullary inhibitory area revealed neurons with atonia-on profiles; tone-on neurons were also found, typically at more lateral sites. Finally, in non-decerebrated pups, chemical lesions within the inhibitory area resulted in significant reductions in atonia durations, as well as decoupling of atonia from a second component of infant sleep, myoclonic twitching; specifically, twitches occasionally occurred during periods of high muscle tone, a condition reminiscent of "REM without atonia" as described in adults. In summary, we document the existence of an area within the ventromedial medulla of infant rats that (i) causes atonia when stimulated; (ii) contains units that exhibit atonia-related discharge profiles during sleep-wake cycling; and (iii) when lesioned, results in the partial loss of atonia and decoupling of the components of sleep. All together, these findings demonstrate that muscle atonia is actively regulated very early in ontogeny.
Assuntos
Bulbo/fisiologia , Tono Muscular/fisiologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/efeitos da radiação , Análise de Variância , Animais , Animais Recém-Nascidos , Hormônio Liberador da Corticotropina/farmacologia , Estado de Descerebração/fisiopatologia , Estimulação Elétrica/métodos , Eletromiografia/métodos , Agonistas de Aminoácidos Excitatórios/farmacologia , Feminino , Masculino , Bulbo/efeitos dos fármacos , Bulbo/efeitos da radiação , Hipotonia Muscular/tratamento farmacológico , Hipotonia Muscular/metabolismo , Hipotonia Muscular/fisiopatologia , Tono Muscular/efeitos dos fármacos , Tono Muscular/efeitos da radiação , Inibição Neural/efeitos dos fármacos , Inibição Neural/fisiologia , Inibição Neural/efeitos da radiação , Ácido Quisquálico/farmacologia , Ratos , Ratos Sprague-Dawley , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologia , Tempo de Reação/efeitos da radiação , Estimulação QuímicaAssuntos
Pressão Sanguínea/fisiologia , Bulbo/fisiologia , Neurônios/fisiologia , Potenciais de Ação/fisiologia , Animais , Vasos Sanguíneos/inervação , Vasos Sanguíneos/fisiologia , Channelrhodopsins , Humanos , Luz , Bulbo/citologia , Bulbo/efeitos da radiação , Neurônios/efeitos da radiação , Feniletanolamina N-Metiltransferase/fisiologia , Medula Espinal/citologia , Medula Espinal/enzimologiaRESUMO
Although interest in descending modulation of spinal cord function dates back to the time of Sherrington, the modern era began in the late 1960s when it was shown that focal electrical stimulation in the midbrain of the rat produced analgesia sufficient to permit surgery. From this report evolved the concept of endogenous systems of pain modulation. Initial interest focused on descending inhibition of spinal nociceptive processing, but we now know that descending modulation of spinal nociceptive processing can be either inhibitory or facilitatory. As our understanding of descending facilitatory, or pro-nociceptive influences grows, so too has our appreciation of its potential importance. Accumulating evidence suggests that descending facilitatory influences may contribute to the development and maintenance of hyperalgesia and thus contribute to chronic pain states.
Assuntos
Vias Eferentes/fisiopatologia , Manejo da Dor , Dor/fisiopatologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/efeitos da radiação , Animais , Vias Eferentes/efeitos dos fármacos , Vias Eferentes/efeitos da radiação , Bulbo/citologia , Bulbo/efeitos dos fármacos , Bulbo/efeitos da radiação , Inibição Neural/efeitos dos fármacos , Inibição Neural/efeitos da radiação , Nociceptores/efeitos dos fármacos , Nociceptores/efeitos da radiação , Estimulação Física/métodos , Ratos , Ratos Sprague-Dawley , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/efeitos da radiação , Glutamato de Sódio/farmacologia , Medula Espinal/fisiopatologiaRESUMO
Various lines of transgenic or knockout mice are now available that have abnormalities in neuron, glial cells or neuron-glial interaction. However, the techniques for quantitative analysis of their pathophysiological functions are still limited. We established an experimental model system to measure the properties of nerve conduction of identified neural pathways in the CNS using anesthetized and immobilized mice. Dorsal column (DC), vestibulospinal/reticulospinal tracts (VRST) and pyramidal tract (PT) were stimulated by inserting stimulating electrodes into the dorsal column nuclei, medial longitudinal fasciculus, and the medullary pyramid, respectively. Volleys were recorded at various segments in the cervical spinal cord with surface electrodes, and their conduction velocities (CVs) and relative refractory periods (RRPs) were measured. The CVs of the DC, VRST and PT were 26.25 +/- 4.96 m/s (n = 7), 51.55 +/- 4.65 m/s (n = 7), 8.89 +/- 1.81 m/s (n = 7), respectively. Data from paired stimulation indicated that the median values of RRPs of the DC, VRST and PT were 10, 2 and 4 ms, respectively, which suggested marked difference among individual tracts. This is the first attempt to measure the conduction properties of the central tracts in mice in vivo. This experimental procedure will give us a physiological measure of CNS functions in normal and genetically manipulated mice and contribute to clarifying the molecular mechanisms and pathophysiology of neurodegenerative diseases such as multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS).
Assuntos
Sistema Nervoso Central/fisiologia , Condução Nervosa/fisiologia , Vias Neurais/fisiologia , Animais , Sistema Nervoso Central/efeitos da radiação , Estimulação Elétrica/métodos , Bulbo/anatomia & histologia , Bulbo/fisiologia , Bulbo/efeitos da radiação , Camundongos , Camundongos Knockout , Condução Nervosa/genética , Condução Nervosa/efeitos da radiação , Vias Neurais/efeitos da radiação , Tempo de Reação/efeitos da radiação , Fatores de Tempo , Fatores de Transcrição/deficiência , Fatores de Transcrição/genéticaRESUMO
Activity within rostral and intermediate ventral medullary surface areas, measured as 660 nm scattered light changes, was examined in six cats, (five experimental, one control site) following 5% CO(2) challenges during waking, quiet sleep, and rapid eye movement (REM) sleep states. Activity declined to hypercapnia in all states, with a smaller decline in quiet sleep compared to waking, and intermediate values in REM sleep. The decline occurred more rapidly, with a shorter latency, during wakefulness, but with a much slower return to baseline than during quiet sleep. During REM sleep, the latency to nadir and recovery were greater than in other states. Regional patterns of activation emerged which differed in extent of activation between states.
Assuntos
Hipercapnia/fisiopatologia , Luz , Bulbo/efeitos da radiação , Sono/fisiologia , Vigília/fisiologia , Animais , Gatos , Diafragma/fisiopatologia , Eletromiografia , Masculino , Bulbo/fisiopatologia , Tempo de Reação , Respiração , Espalhamento de Radiação , Sono REM/fisiologiaRESUMO
The facial nucleus (FN) has been known as a motor nucleus to control the activity of the facial skeletal muscles by its efferent somatic motoneurons. Much less, however, is known about the non-motor control functions of its interneurons. The present study was designed to investigate if the interneurons of the FN participate in controlling rhythmic respiration in the sodium thiopental-anesthetized and vagotomized Sprague-Dawley rats with facial motoneurons retrogradely degenerated with techniques of electrical and chemical stimulation of the FN and extracellular recording of discharge of neurons in the FN. Single pulse stimulation (75-100 microA, 0.2 ms) of the FN during inspiration caused a transient restrain in phrenic discharge. Short train stimulation (75-100 microA, 0.2 ms, 100 Hz, 3-5 pulses) delivered during the early- or mid-term of inspiration augmented the inspiratory duration, but switched the inspiration off when delivered during the later stage of inspiration. Short train stimulation delivered during expiration prolonged the expiratory duration. Continuous stimulation could inhibit the inspiration. Microinjection of kainic acid into the FN caused an augmentation in inspiratory duration and amplitude and in expiratory duration. These data indicate that the interneurons of the FN might participate in the modulation of respiration. Different discharge patterns of interneurons in the FN, interestingly some respiratory related patterns, were observed, which provide a possible structural basis for the role of the FN in respiratory regulation.
Assuntos
Nervo Facial/fisiologia , Bulbo/fisiologia , Respiração , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/efeitos da radiação , Animais , Relação Dose-Resposta à Radiação , Estimulação Elétrica/métodos , Agonistas de Aminoácidos Excitatórios/farmacologia , Feminino , Ácido Caínico/farmacologia , Masculino , Bulbo/citologia , Bulbo/efeitos dos fármacos , Bulbo/efeitos da radiação , Microinjeções/métodos , Neurônios Motores/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/efeitos da radiação , Ratos , Ratos Sprague-Dawley , Respiração/efeitos dos fármacos , Respiração/efeitos da radiação , Fatores de Tempo , Vagotomia/métodosRESUMO
Although perinuclear anti-neutrophil cytoplasmic antibodies (pANCA) are associated with vasculitic neuropathy, their association with central nervous system (CNS) disorders has not been studied except for one report on optic-spinal type of multiple sclerosis associated with serum pANCA. We examined pANCA in sera from 98 patients with various CNS disorders, such as 58 MS, 17 myelitis, 12 HTLV-1 associated myelopathy, and 11 other CNS diseases using indirect immunofluorescence methods. The results showed serum pANCA to be positive in five patients with a peculiar type of myelitis, including two with MS and three with etiology unknown myelitis. All of these ANCA-positive patients were women and had acute or subacute myelopathy with various severities. MRI revealed segmental swelling of the spinal cord with T2 hyperintensity in the acute stage of the disease. Marked pleocytosis (227.8+/-101/mm3) and elevated protein level (128.8+/-52 mg/dl) in CSF were noted. Four of the patients had anti-nuclear antibodies and two had previous histories of symptoms suggesting autoimmune disorders. In a search for target antigens of pANCA, myeloperoxidase reactivity was found in the sera from two myelitis patients. Clinical and laboratory features of myelitis patients with pANCA in the present study are different from those of typical MS patients. Further study will be needed to delineate the role of pANCA in the pathogenesis of a specific type of myelitis.
Assuntos
Anticorpos Anticitoplasma de Neutrófilos/sangue , Mielite/imunologia , Neutrófilos/imunologia , Adolescente , Adulto , Contagem de Células , Doenças do Sistema Nervoso Central , Líquido Cefalorraquidiano/citologia , Líquido Cefalorraquidiano/imunologia , Ensaio de Imunoadsorção Enzimática , Feminino , Técnica Indireta de Fluorescência para Anticorpo , Humanos , Soros Imunes/química , Imageamento por Ressonância Magnética , Bulbo/imunologia , Bulbo/efeitos da radiação , Pessoa de Meia-Idade , Mielite/patologia , Medula Espinal/imunologia , Medula Espinal/efeitos da radiaçãoRESUMO
The role of the area postrema in radiation-induced emesis and taste aversion learning and the relationship between these behaviors were studied in cats. The potential involvement of neural factors which might be independent of the area postrema was minimized by using low levels of ionizing radiation (100 rads at a dose rate of 40 rads/min) to elicit a taste aversion, and by using body-only exposures (4500 and 6000 rads at 450 rads/min) to produce emesis. Lesions of the area postrema disrupted both taste aversion learning and emesis following irradiation. These results, which indicate that the area postrema is involved in the mediation of both radiation-induced emesis and taste aversion learning in cats under these experimental conditions, are interpreted as being consistent with the hypotheses that similar mechanisms mediate both responses to exposure to ionizing radiation, and that the taste aversion learning paradigm can therefore serve as a model system for studying radiation-induced emesis.
Assuntos
Aprendizagem da Esquiva/fisiologia , Condicionamento Clássico/fisiologia , Bulbo/fisiologia , Sistemas Neurossecretores/fisiologia , Paladar/fisiologia , Animais , Mapeamento Encefálico , Gatos , Bulbo/efeitos da radiação , Sistemas Neurossecretores/efeitos da radiação , Paladar/efeitos da radiação , Vômito/fisiopatologiaRESUMO
To clarify the anatomical location of medullary neurons associated with vomiting, the musk shrew (Suncus murinus), a small animal used as a model for emesis, was exposed to various emetic stimuli and patterns of neuronal excitation were investigated by Fos immunohistochemistry. In motion experiments, musk shrews were shaken for 30 min on a tabletop shaker (displacement=25 mm and frequency=1.2 Hz). Ten of fifteen animals vomited frequently (Mo-FV group); the other five animals did not vomit (Mo-NV group). In radiation experiments, X-ray irradiation (10 Gy) of the whole body caused frequent vomiting in all of seven experimental animals (Ra-FV group). In the Mo-FV group, many Fos-immunoreactive (Fos-ir) neurons were detected in the nucleus of the solitary tract (NTS) and the reticular formation. The distribution pattern of Fos-ir neurons in the Mo-NV group was similar to that in the Mo-FV group, but the Mo-NV group had significantly fewer positive neurons in the NTS and the reticular formation around the nucleus ambiguus. In the Ra-FV group, numerous Fos-ir neurons were observed in the area postrema, an area containing no positive neurons in the motion-stimulated animals. The number of Fos-ir neurons in the NTS of the Ra-FV group was not statistically different from that of the Mo-NV group. In the Mo-FV and Ra-FV groups, Fos-ir neurons were clustered in the reticular formation at the dorsal-dorsomedial edge of the nucleus ambiguus at the level of the rostral medulla, while few such clusters were observed in the Mo-NV group. These neurons may play a role in the regulation of the vomiting response.
Assuntos
Bulbo/efeitos da radiação , Movimento (Física) , Proteínas Proto-Oncogênicas c-fos/biossíntese , Vômito/metabolismo , Raios X/efeitos adversos , Animais , Contagem de Células/métodos , Feminino , Imuno-Histoquímica , Masculino , Bulbo/metabolismo , Neurônios/metabolismo , Musaranhos , Vômito/patologiaRESUMO
PURPOSE: Determination of the radiation doses in spiral CT of the paranasal sinuses using a variety of mAs values and scan protocols. MATERIAL AND METHODS: CT examinations of the paranasal sinuses were performed using an Alderson-Rando phantom. Radiation dose was determined by LiF-TLD at the level of high risk organs in the head and neck region for combinations of different scan parameters (2/3, 3/3, 3/4 mm) and decreasing charges (200, 150, 100, 50, 25 mAs) on a spiral CT. Additional measurements were performed on three other CT scanners using the 2/3 mm protocol at 50 mAs, and a single slice technique (5/5 mm) on one scanner. RESULTS: The lowest dose values found were 1.88 mGy for the eye lenses, 1.35 mGy for the parotid gland, 0.03 mGy for the thyroid gland and 0.1 mGy for the medulla oblongata using 2 mm collimation and 3 mm table feed at 25 mAs. Maximal dose values resulted using the 3/3 mm protocol at 200 mAs (31.00 mGy for the eye lense, 0.65 mGy for the thyroid gland). There were no significant differences found between the different CT scanners. CONCLUSIONS: Using up-to-date CT scanners, radiation exposure may be reduced by a factor of 15-20 compared to that of conventional CT technique. Thus, the exposure of the eye lens comes to only a thousandth of the value supposedly inducing a cataract, as published by the ICRP.
Assuntos
Seios Paranasais/diagnóstico por imagem , Doses de Radiação , Dosimetria Termoluminescente , Tomografia Computadorizada por Raios X/efeitos adversos , Humanos , Cristalino/efeitos da radiação , Bulbo/efeitos da radiação , Glândula Parótida/efeitos da radiação , Imagens de Fantasmas , Glândula Tireoide/efeitos da radiação , Tomografia Computadorizada por Raios X/instrumentaçãoAssuntos
Anuros/efeitos da radiação , Cerebelo/efeitos da radiação , Orelha Interna/radioterapia , Bulbo/efeitos da radiação , Neurônios Motores/efeitos da radiação , Células de Purkinje/efeitos da radiação , Efeitos da Radiação , Lesões Experimentais por Radiação , Animais , Gatos , Cricetinae , Cães , Feminino , Cobaias , Haplorrinos , Masculino , Camundongos , Coelhos , RatosRESUMO
AIM: To determine the role of area postrema (AP) of rabbit in the regulation of cardiovascular function. METHODS: The rabbits were anesthetized with intravenous injection of 10% urethane and 1% chloralose, and were artificially ventilated. The changes of mean arterial pressure (MAP) and heart rate (HR) were observed when AP was electrically stimulated with different frequency (10 Hz -80 Hz) and after chemical lesion of CVLM or RVLM, respectively. RESULTS: Electrical stimulation of AP with low frequency (10 Hz, 20 Hz) decreased MAP and HR. Stimulation with high frequency(60 Hz, 80 Hz) increased MAP but decreased HR. The changes in MAP and HR were significantly lower (P < 0.01) after CVLM was destroyed when electrical stimulation of AP with 20 Hz, and both changes of MAP and HR were disappeared (P < 0.01) after RVLM was destroyed when electrical stimulation with 20 and 80 Hz. CONCLUSION: Electrical stimulation of AP with low frequency decreases MAP and HR, stimulation with high frequency induces an increase in MAP and decreases in HR. The former is probably related to excitation of CVLM, the cardiovascular effects induced by different frequency of electrical stimulation are all resulted from the activation of RVLM.