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José E Cavazos

Bio: José E Cavazos is an academic researcher from University of Texas Health Science Center at San Antonio. The author has contributed to research in topics: Epilepsy & Dentate gyrus. The author has an hindex of 29, co-authored 77 publications receiving 5947 citations. Previous affiliations of José E Cavazos include Tan Tock Seng Hospital & University of Texas at San Antonio.


Papers
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Journal ArticleDOI
TL;DR: The results are morphological evidence of mossy Fiber synaptic reorganization in the temporal lobe of epileptic humans, and suggest the intriguing possibility that mossy fiber sprouting and synaptic reorganizing induced by repeated partial complex seizures may play a role in human epilepsy.
Abstract: The distribution of the mossy fiber synaptic terminals was examined using the Timm histochemical method in surgically excised hippocampus and dentate gyrus from patients who underwent lobectomy of the anterior part of the temporal lobe for refractory partial complex epilepsy The dentate gyrus of epileptic patients demonstrated intense Timm granules and abundant mossy fiber synaptic terminals in the supragranular region and the inner molecular layer In contrast, the dentate gyrus of presenescent nonepileptic primates demonstrated no Timm granules in the supragranular region In nonepileptic senescent primates, occasional very sparse supragranuler Timm granules were observed that were easily distinguished from the dense pattern observed in association with human epilepsy The results are morphological evidence of mossy fiber synaptic reorganization in the temporal lobe of epileptic humans, and suggest the intriguing possibility that mossy fiber sprouting and synaptic reorganization induced by repeated partial complex seizures may play a role in human epilepsy

1,106 citations

Journal ArticleDOI
04 Mar 1988-Science
TL;DR: In this paper, morphological evidence was provided that synchronous perforant path activation and kindling of limbic pathways induce axonal growth and synaptic reorganization in the hippocampus, in the absence of overt morphological damage.
Abstract: Abnormal functional activity induces long-lasting physiological alterations in neural pathways that may play a role in the development of epilepsy. The cellular mechanisms of these alterations are not well understood. One hypothesis is that abnormal activity causes structural reorganization of neural pathways and promotes epileptogenesis. This report provides morphological evidence that synchronous perforant path activation and kindling of limbic pathways induce axonal growth and synaptic reorganization in the hippocampus, in the absence of overt morphological damage. The results show a previously unrecognized anatomic plasticity associated with synchronous activity and development of epileptic seizures in neural pathways.

878 citations

Journal ArticleDOI
TL;DR: A strong correlation between mossy fiber synaptic reorganization and the development, progression, and permanence of the kindling phenomenon is demonstrated.
Abstract: Recent studies have revealed that mossy fiber axons of granule cells in the dentate gyrus undergo reorganization of their terminal projections in both animal models of epilepsy and human epilepsy This synaptic reorganization has been demonstrated by the Timm method, a histochemical technique that selectively labels synaptic terminals of mossy fibers because of their high zinc content It has been generally presumed that the reorganization of the terminal projections of the mossy fiber pathway is a consequence of axonal sprouting and synaptogenesis by mossy fibers To evaluate this possibility further, the time course for development of Timm granules, which correspond ultrastructurally to mossy fiber synaptic terminals, was examined in the supragranular layer of the dentate gyrus at the initiation of kindling stimulation with an improved scoring method for assessment of alterations in Timm histochemistry The progression and permanence of this histological alteration were similarly evaluated during the behavioral and electrographic evolution of kindling evoked by perforant path, amygdala, or olfactory bulb stimulation Mossy fiber synaptic terminals developed in the supragranular region of the dentate gyrus by 4 d after initiation of kindling stimulation in a time course compatible with axon sprouting The induced alterations in the terminal projections of the mossy fiber pathway progressed with the evolution of behavioral kindled seizures, became permanent in parallel with the development of longlasting susceptibility to evoked seizures, and were observed as long as 8 months after the last evoked kindled seizure The results demonstrated a strong correlation between mossy fiber synaptic reorganization and the development, progression, and permanence of the kindling phenomenon

501 citations

Journal ArticleDOI
TL;DR: These 13 brief measures of self-reported QOL are reliable and show preliminary evidence of concurrent validity inasmuch as they differentiate people based upon number of reported health conditions and whether those reported conditions impede normal function.
Abstract: Objective: To address the need for brief, reliable, valid, and standardized quality of life (QOL) assessment applicable across neurologic conditions. Methods: Drawing from larger calibrated item banks, we developed short measures (8–9 items each) of 13 different QOL domains across physical, mental, and social health and evaluated their validity and reliability. Three samples were utilized during short form development: general population (Internet-based, n = 2,113); clinical panel (Internet-based, n = 553); and clinical outpatient (clinic-based, n = 581). All short forms are expressed as T scores with a mean of 50 and SD of 10. Results: Internal consistency (Cronbach α) of the 13 short forms ranged from 0.85 to 0.97. Correlations between short form and full-length item bank scores ranged from 0.88 to 0.99 (0.82–0.96 after removing common items from banks). Online respondents were asked whether they had any of 19 different chronic health conditions, and whether or not those reported conditions interfered with ability to function normally. All short forms, across physical, mental, and social health, were able to separate people who reported no health condition from those who reported 1–2 or 3 or more. In addition, scores on all 13 domains were worse for people who acknowledged being limited by the health conditions they reported, compared to those who reported conditions but were not limited by them. Conclusion: These 13 brief measures of self-reported QOL are reliable and show preliminary evidence of concurrent validity inasmuch as they differentiate people based upon number of reported health conditions and whether those reported conditions impede normal function.

459 citations

Journal ArticleDOI
TL;DR: It is suggested that hippocampal sclerosis may be acquired in human epilepsy as a consequence of repeated seizures because of selective vulnerability of hippocampal neuronal populations to seizure-induced injury, and even brief seizures may induce excitotoxic injury in vulnerable neuronal populations.
Abstract: Repeated kindled seizures induce long-lasting physiological and morphological alterations in the hippocampal formation. In the dentate gyrus (DG), the morphological alterations induced by kindled seizures include loss of polymorphic neurons in the hilus, mossy fiber axon sprouting, and synaptic reorganization of the mossy fiber pathway. In this study, quantitative stereological methods were used to determine the distribution and time course of neuronal loss induced by 3, 30, or 150 kindled generalized tonic-clonic seizures in hippocampal, limbic, and neocortical pathways. Neuronal loss was observed in the hilus of the DG and CA1 after three generalized tonic-clonic seizures, and progressed in these sites to 49% and 44% of controls after 150 seizures. Neuronal loss was also observed in CA3, entorhinal cortex, and the rostral endopyriform nucleus after 30 seizures, and was detected in the granule cell layer and CA2 after 150 seizures. There was no evidence of neuronal loss in the somatosensory cortex after 150 seizures. The time course of the neuronal loss demonstrated selective vulnerability of hippocampal neuronal populations to seizure-induced injury, and suggests that even brief seizures may induce excitotoxic injury in vulnerable neuronal populations. Repeated brief seizures induced neuronal loss in a distribution that resembled hippocampal sclerosis, the most common lesion observed in human epilepsy. The results demonstrated that kindling induces alterations in neural circuitry in a variety of locations in the limbic system, and suggest that hippocampal sclerosis may be acquired in human epilepsy as a consequence of repeated seizures.

451 citations


Cited by
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Journal ArticleDOI
06 Jun 1986-JAMA
TL;DR: The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or her own research.
Abstract: I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

7,563 citations

Journal ArticleDOI
TL;DR: Observations indicate that prolonged seizure discharges stimulate dentate granule cell neurogenesis, and that hippocampal network plasticity associated with epileptogenesis may arise from aberrant connections formed by newly born dentategranule cells.
Abstract: The dentate granule cell layer of the rodent hippocampal formation has the distinctive property of ongoing neurogenesis that continues throughout adult life. In both human temporal lobe epilepsy and rodent models of limbic epilepsy, this same neuronal population undergoes extensive remodeling, including reorganization of mossy fibers, dispersion of the granule cell layer, and the appearance of granule cells in ectopic locations within the dentate gyrus. The mechanistic basis of these abnormalities, as well as their potential relationship to dentate granule cell neurogenesis, is unknown. We used a systemic chemoconvulsant model of temporal lobe epilepsy and bromodeoxyuridine (BrdU) labeling to investigate the effects of prolonged seizures on dentate granule cell neurogenesis in adult rats, and to examine the contribution of newly differentiated dentate granule cells to the network changes seen in this model. Pilocarpine-induced status epilepticus caused a dramatic and prolonged increase in cell proliferation in the dentate subgranular proliferative zone (SGZ), an area known to contain neuronal precursor cells. Colocalization of BrdU-immunolabeled cells with the neuron-specific markers turned on after division, 64 kDa, class III β-tubulin, or microtubule-associated protein-2 showed that the vast majority of these mitotically active cells differentiated into neurons in the granule cell layer. Newly generated dentate granule cells also appeared in ectopic locations in the hilus and inner molecular layer of the dentate gyrus. Furthermore, developing granule cells projected axons aberrantly to both the CA3 pyramidal cell region and the dentate inner molecular layer. Induction of hippocampal seizure activity by perforant path stimulation resulted in an increase in SGZ mitotic activity similar to that seen with pilocarpine administration. These observations indicate that prolonged seizure discharges stimulate dentate granule cell neurogenesis, and that hippocampal network plasticity associated with epileptogenesis may arise from aberrant connections formed by newly born dentate granule cells.

1,883 citations

Journal ArticleDOI
TL;DR: The results suggest that depression is associated with hippocampal atrophy, perhaps due to a progressive process mediated by glucocorticoid neurotoxicity.
Abstract: Hippocampal volumes of subjects with a history of major depressive episodes but currently in remission and with no known medical comorbidity were compared to matched normal controls by using volumetric magnetic resonance images. Subjects with a history of major depression had significantly smaller left and right hippocampal volumes with no differences in total cerebral volumes. The degree of hippocampal volume reduction correlated with total duration of major depression. In addition, large (diameter > or = 4.5 mm)-hippocampal low signal foci (LSF) were found within the hippocampus, and their number also correlated with the total number of days depressed. These results suggest that depression is associated with hippocampal atrophy, perhaps due to a progressive process mediated by glucocorticoid neurotoxicity.

1,856 citations

Journal ArticleDOI
TL;DR: The author postulates that both sensitization to stressors and episode sensitization occur and become encoded at the level of gene expression, suggesting that the biochemical and anatomical substrates underlying the affective disorders evolve over time as a function of recurrences, as does pharmacological responsivity.
Abstract: Early clinical observations and recent systematic studies overwhelmingly document a greater role for psychosocial stressors in association with the first episode of major affective disorder than with subsequent episodes. The author postulates that both sensitization to stressors and episode sensitization occur and become encoded at the level of gene expression. In particular, stressors and the biochemical concomitants of the episodes themselves can induce the protooncogene c-fos and related transcription factors, which then affect the expression of transmitters, receptors, and neuropeptides that alter responsivity in a long-lasting fashion. Thus, both stressors and episodes may leave residual traces and vulnerabilities to further occurrences of affective illness. These data and concepts suggest that the biochemical and anatomical substrates underlying the affective disorders evolve over time as a function of recurrences, as does pharmacological responsivity. This formulation highlights the critical importance of early intervention in the illness in order to prevent malignant transformation to rapid cycling, spontaneous episodes, and refractoriness to drug treatment.

1,741 citations