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Digestive Diseases and Sciences Aug 1999Nausea and vomiting (emesis) occur under a variety of conditions in response to activation of one or more emetic triggers. The act of vomiting is coordinated by neuronal... (Review)
Review
Nausea and vomiting (emesis) occur under a variety of conditions in response to activation of one or more emetic triggers. The act of vomiting is coordinated by neuronal circuitry located in the brain stem between the obex and the retrofacial nucleus, including the region extending from the nucleus of the solitary tract through the lateral tegmental field of the reticular formation to the ventrolateral medulla. The area postrema, medullary midline, and certain higher brain centers are also important for vomiting. The sensation of nausea is thought to involve the cerebral cortex. The most effective near-term treatment for combating nausea and vomiting associated with cyclic vomiting syndrome may come from experimental drugs (NK-1 receptor antagonists, 5-HT1A receptor agonists) or P6 acustimulation, which have been shown to combat nausea and vomiting in response to a broad spectrum of emetic challenges and thus presumably act on central emetic mechanisms.
Topics: Acupuncture Points; Adolescent; Adult; Animals; Antiemetics; Brain Mapping; Brain Stem; Child; Child, Preschool; Humans; Infant; Nerve Net; Periodicity; Syndrome; Vomiting
PubMed: 10490038
DOI: No ID Found -
Physiology & Behavior Mar 1982A study was carried out on the effect of topical application of 3.0 micrograms/microliters noradrenalin (NA) to the obex of awake guinea pigs bearing electrolyte lesions...
A study was carried out on the effect of topical application of 3.0 micrograms/microliters noradrenalin (NA) to the obex of awake guinea pigs bearing electrolyte lesions and submitted to noxious peripheral stimulation (electric pulses). The animals with extensive lesions covering the area postrema (AP) and the solitary tract nucleus (STN) showed a marked increase in vocalization (V) and defense motor response (M) to the noxious peripheral stimulus after NA application. In the group bearing lesions restricted to the AP, the analgesic effect of NA was potentiated, with a marked decrease in V and M after noxious peripheral stimulation. These results suggest that the integrity of the STN is a fundamental requirement for the analgesic effect of NA topically applied to the obex, and that the AP may have an inhibitory tonic action on the STN in the modulation of the noxious reaction.
Topics: Animals; Cranial Nerves; Electric Stimulation; Ependyma; Guinea Pigs; Male; Medulla Oblongata; Motor Activity; Norepinephrine; Pain; Vocalization, Animal
PubMed: 7079356
DOI: 10.1016/0031-9384(82)90133-0 -
Journal of Veterinary Diagnostic... Jan 2008Chronic wasting disease (CWD) in Wisconsin was first identified in February 2002. By April 2005, medial retropharyngeal lymph node (RLN) tissues had been examined from... (Comparative Study)
Comparative Study
Chronic wasting disease (CWD) in Wisconsin was first identified in February 2002. By April 2005, medial retropharyngeal lymph node (RLN) tissues had been examined from over 75,000 white-tailed deer for the presence of CWD by either immunohistochemical (IHC) staining for the prion protein associated with CWD (PrP(res)) or by using enzyme-linked immunosorbent assays with confirmation of positives by IHC staining and had been detected in 469 animals. Obex tissue was also available from 438 of the CWD-positive animals and was CWD positive by IHC staining in 355 (81%). To verify whether false-negative results were possible examining only RLN, both obex and RLN samples were examined for CWD by IHC staining from 4,430 of the white-tailed deer harvested from an area in Wisconsin where the overall deer CWD prevalence was approximately 6.2%. Two hundred and fourteen of the 269 positive deer (79.6%) had deposits of PrP(res) in both obex and lymphoid tissues, 55 (20.4%) had deposits only in lymphoid tissue, and there were no deer that had deposits only in obex.
Topics: Animals; Brain Stem; Deer; Enzyme-Linked Immunosorbent Assay; Immunohistochemistry; Lymph Nodes; Wasting Disease, Chronic
PubMed: 18182509
DOI: 10.1177/104063870802000110 -
Brain Research Dec 1977
Topics: Afferent Pathways; Animals; Anura; Cerebral Ventricles; Medulla Oblongata; Rana catesbeiana; Rana pipiens; Ranidae; Reticular Formation; Spinal Cord; Thalamus
PubMed: 304371
DOI: 10.1016/0006-8993(77)90688-6 -
Child's Nervous System : ChNS :... Oct 2015Modern understanding of the relation between the mutated cancer stem cell and its site of origin and of its interaction with the tissue environment is enhancing the... (Review)
Review
INTRODUCTION
Modern understanding of the relation between the mutated cancer stem cell and its site of origin and of its interaction with the tissue environment is enhancing the importance of developmental anatomy in the diagnostic assessment of posterior fossa tumors in children. The aim of this review is to show how MR imaging can improve on the exact identification of the tumors in the brainstem and in the vicinity of the fourth ventricle in children, using both structural imaging data and a precise topographical assessment guided by the developmental anatomy.
RESULTS
The development of the hindbrain results from complex processes of brainstem segmentation, ventro-dorsal patterning, multiple germinative zones, and diverse migration pathways of the neural progenitors. Depending on their origin in the brainstem, gliomas may be infiltrative or not, as well as overwhelmingly malignant (pons), or mostly benign (cervicomedullary, medullo-pontine tegmental, gliomas of the cerebellar peduncles). In the vicinity of the fourth ventricles, the prognosis of the medulloblastomas (MB) correlates the molecular subtyping as well as the site of origin: WNT MB develop from the Wnt-expressing lower rhombic lip and have a good prognosis; SHH MB develop from the Shh-modulated cerebellar cortex with an intermediate prognosis (dependent on age); recurrences are local mostly. The poor prognosis group 3 MB is radiologically heterogeneous: some tumors present classic features but are juxtaventricular (rather than intraventricular); others have highly malignant features with a small principal tumor and an early dissemination. Group 4 MB has classic features, but characteristically usually does not enhance; dissemination is common. Although there is as yet no clear molecular subgrouping of the ependymomas, their sites of origin and their development can be clearly categorized, as most develop in an exophytic way from the ventricular surface of the medulla in clearly specific locations: the obex region with expansion in the cistern magna, or the lateral recess region with expansion in the CPA and prepontine cisterns (cerebellar ependymomas, and still more intra-brainstem ependymomas are rare). Finally, almost all cerebellar gliomas are pilocytic astrocytomas.
CONCLUSIONS
A developmental and anatomic approach to the posterior fossa tumors in children (together with diffusion imaging data) provides a reliable pre-surgical identification of the tumor and of its aggressiveness.
Topics: Child; Cranial Fossa, Posterior; Diagnostic Imaging; Ependymoma; Glioma; Humans; Infratentorial Neoplasms; Medulloblastoma
PubMed: 26351220
DOI: 10.1007/s00381-015-2834-z -
Brain Research Mar 1978The ultrastructure of the dorsal column nucleus (DCN) has been investigated at the level of the obex region in normal and experimental toads. Large 'isolated' neurons...
The ultrastructure of the dorsal column nucleus (DCN) has been investigated at the level of the obex region in normal and experimental toads. Large 'isolated' neurons (greater than 20 micrometer) and clusters of small neurons (less than 20 micrometer) have been identified in this region. Synaptic profiles have been classified into three types: large 'en passant' LR boutons, containing round synaptic vesicles and neurofilaments, small R boutons with round vesicles and F boutons with pleomorphic vesicles. The axon terminals exhibited synaptic contacts with cell somata, with dendrites of varying calibers and with other axons. The terminals involved in the axo-axonic contact were the F boutons which were presynaptic to the LR boutons, thus representing the morphological basis for presynaptic inhibition. Transection of the second dorsal root was performed in order to identify the terminals of the primary afferents to the DCN, after different survival periods (16 h--50 days). Only the LR boutons underwent degeneration, thus representing the central endings of the primary dorsal root afferents. The functional significance of these findings was discussed.
Topics: Animals; Axons; Bufo bufo; Ganglia, Spinal; Nerve Degeneration; Neurons
PubMed: 416880
DOI: 10.1016/0006-8993(78)90905-8 -
Journal of Veterinary Diagnostic... Jul 2015The purpose of our study was to describe the progressive accumulation of the abnormal conformer of the prion protein (PrP(CWD)) and spongiform degeneration in a single...
Progressive accumulation of the abnormal conformer of the prion protein and spongiform encephalopathy in the obex of nonsymptomatic and symptomatic Rocky Mountain elk (Cervus elaphus nelsoni) with chronic wasting disease.
The purpose of our study was to describe the progressive accumulation of the abnormal conformer of the prion protein (PrP(CWD)) and spongiform degeneration in a single section of brain stem in Rocky Mountain elk (Cervus elaphus nelsoni) with chronic wasting disease (CWD). A section of obex from 85 CWD-positive elk was scored using the presence and abundance of PrP(CWD) immunoreactivity and spongiform degeneration in 10 nuclear regions and the presence and abundance of PrP(CWD) in 10 axonal tracts, the subependymal area of the fourth ventricle, and the thin subpial astrocytic layer (glial limitans). Data was placed in a formula to generate an overall obex score. Data suggests that PrP(CWD) immunoreactivity and spongiform degeneration has a unique and relatively consistent pattern of progression throughout a section of obex. This scoring technique utilizing a single section of obex may prove useful in future work for estimating the presence and abundance of PrP(CWD) in peripheral tissues and the nervous system in elk with CWD.
Topics: Animals; Brain; Deer; Prion Diseases; Prions; Protein Conformation; Protein Isoforms; Wasting Disease, Chronic
PubMed: 26185123
DOI: 10.1177/1040638715593368 -
Prion 2015Prion proteins (PrP(C)) are cell membrane glycoproteins that can be found in many cell types, but specially in neurons. Many studies have suggested PrP(C)'s...
Prion proteins (PrP(C)) are cell membrane glycoproteins that can be found in many cell types, but specially in neurons. Many studies have suggested PrP(C)'s participation in metal transport and cellular protection against stress in the central nervous system (CNS). On the other hand PrP(Sc), the misfolded isoform of PrP(C) and the pathogenic agent in transmissible spongiform encephalopathies (TSE), has been associated with brain metal dyshomeostasis in prion diseases. Thus, changes in metal concentration associated with protein misfolding and aggregation have been reported for human and animal prion diseases, as well as for other neurodegenerative disorders, such as Parkinson's and Alzheimer's disease. The use of metal concentrations in tissues as surrogate markers for early detection of TSEs has been suggested. Studies on the accumulation of metals in free-ranging white-tailed deer have not been conducted. This study established concentrations of copper, iron, manganese, and magnesium in 2 diagnostic tissues used for CWD testing (obex and retropharyngeal lymph nodes (RLN)). We compared these concentrations between tissues and in relation to CWD status. We established reference intervals (RIs) for these metals and explored their ability to discriminate between CWD-positive and CWD-negative animals. Our results indicate that independent of CWD status, white-tailed deer accumulate higher concentrations of Fe, Mn and Mg in RLN than in obex. White-tailed deer infected with CWD accumulated significantly lower concentrations of Mn and Fe than CWD-negative deer. These patterns differed from other species infected with prion diseases. Overlapping values between CWD positive and negative groups indicate that evaluation of these metals in obex and RLN may not be appropriate as a diagnostic tool for CWD infection in white-tailed deer. Because the CWD-negative deer were included in constructing the RIs, high specificities were expected and should be interpreted with caution. Due to the low sensitivity derived from the RIs, we do not recommend using metal concentrations for disease discrimination.
Topics: Animals; Deer; Illinois; Lymph Nodes; Metals; Models, Biological; Sensitivity and Specificity; Wasting Disease, Chronic
PubMed: 25695915
DOI: 10.1080/19336896.2015.1019194 -
The American Journal of Physiology Nov 1986To study the role of the dorsomedial hindbrain in cholecystokinin (CCK)-induced satiety, lesions were produced in the region of the obex. We observed that lesions that...
To study the role of the dorsomedial hindbrain in cholecystokinin (CCK)-induced satiety, lesions were produced in the region of the obex. We observed that lesions that were limited to the area postrema (AP) and immediately adjacent nucleus of the solitary tract (NST) did not attenuate the satietogenic effects of CCK. Similarly, lesions of the medial NST rostral to the AP had no effect on CCK-induced satiety. However, when the majority of the medial and commissural subnuclei of the NST as well as the AP were lesioned, there was a significant attenuation of the satietogenic effect of CCK. Since this lesion includes the bulk of the terminal field from the gastric branch of the vagus nerve, these results support the role of gastric afferent projections in the mediation of CCK-induced satiety. Although we do not rule out the possibility that the AP itself monitors circulating CCK, our data clearly show that the AP is not essential for induction of satiety by exogenous CCK.
Topics: Animals; Avoidance Learning; Bombesin; Brain; Cerebral Ventricles; Cholecystokinin; Conditioning, Psychological; Eating; Food; Male; Medulla Oblongata; Rats; Rats, Inbred Strains; Satiation; Satiety Response
PubMed: 3777222
DOI: 10.1152/ajpregu.1986.251.5.R971 -
Acta Neurochirurgica 1997In 1993 Kyoshima et al. introduced safe entry zones in the region of the 4th ventricle floor: infrafacial triangle and suprafacial triangle. Is it possible to demarcate... (Review)
Review
In 1993 Kyoshima et al. introduced safe entry zones in the region of the 4th ventricle floor: infrafacial triangle and suprafacial triangle. Is it possible to demarcate these zones precisely in every case intra-operatively? A postmortem study of 40 brainstems of patients who had died of non-brain disease was performed to evaluate the degree of individual morphological and morphometrical variability of the 4th ventricle floor. The purpose of this study was to find constant landmarks and distances within the rhomboid fossa region which would help a neurosurgeon to determine safe approach zones through the 4th ventricle floor to brainstem lesions. Several anatomical landmarks-median sulcus, obex, vestibular area, vagal triangle, hypoglossal triangle-were found to be sufficiently visible in all examined brainstems. However, the facial colliculus which is a border structure between the infrafacial and suprafacial safe approach zone was poorly visible in about 37% of the analyzed material. The striae medullares were not found to be good orientation structures as they were not visible in 30% of the material and exhibited individual variability of a high degree in relation to their number and arrangement. In the morphometrical study analyzed measurements were taken by utilizing the digital image analyzer MULTISCAN. Based on the results obtained the authors suggest new borders of the infrafacial safe approach zone and morphometrical directions to determine the suprafacial safe approach zone in cases when the facial colliculus is not clearly visible or invisible intra-operatively.
Topics: Adult; Aged; Aged, 80 and over; Brain Stem; Cerebral Ventricles; Female; Humans; Male; Middle Aged; Models, Neurological
PubMed: 9442213
DOI: 10.1007/BF01411553