Surgical Lesion (surgical + lesion)

Distribution by Scientific Domains

Selected Abstracts

Lesion studies targeting food-anticipatory activity

Alec J. Davidson
Abstract Behavior ablation remains a powerful, if not cutting-edge, approach for localization of function within the nervous system. The initial discovery of the suprachiasmatic nuclei as the site of the mammalian light-entrainable circadian pacemaker is owed to this approach. Food-anticipatory activity (FAA), an output of a putative feeding-entrainable circadian pacemaker, is a behavior that has been surprisingly resilient to elimination by surgical lesion. Here we review this literature, with particular attention paid to recent studies aimed at defining the role of the dorsomedial hypothalamus in the generation of FAA. This literature is fraught with examples of inconsistent results among lesion studies, which in some cases can be accounted for by varied endpoint measures. The site of the feeding-entrainable circadian pacemaker, if it resides in a discrete structure at all, remains unknown. [source]

NG2 proteoglycan-expressing cells of the adult rat brain: Possible involvement in the formation of glial scar astrocytes following stab wound

GLIA, Issue 3 2005
G. Alonso
Abstract Stab wound lesion to the adult central nervous system induces strong proliferative response that is followed by the formation of a dense astroglial scar. In order to determine the origin of those astrocytes composing the glial scar, the cell proliferation marker bromodeoxyuridine (BrdU) was administered to lesioned rats that were fixed 3 h or 6 days later. At 3 h after the BrdU administration, labeled nuclei were frequently associated with either NG2+ cells or microglia/macrophages, but rarely with astrocytes expressing glial fibrillary acidic protein (GFAP). Six days later, by contrast, numerous BrdU-labeled nuclei were associated with astrocytes located along the lesion borders. After the injection of a viral vector of the green fluorescent protein (GFP) into the lesional cavity, GFP was preferentially detected within NG2- or GFAP-labeled cells when lesioned animals were fixed 1 or 6 days after the injections, respectively. The combined detection of glial markers within cells present in the lesioned area indicated that, although they rarely express GFAP, the marker of mature astrocytes, NG2+ cells located along the lesion borders frequently express nestin and vimentin, i.e., two markers of immature astrocytes. Lastly, chronic treatment of lesioned rats with dexamethasone was found to inhibit the proliferation of NG2+ cells present within the lesioned area and to subsequently alter the formation of a dense astroglial scar. Taken together, these data strongly suggest that following a surgical lesion, at least a portion of the astrocytes that constitute the glial scar are issued from resident NG2+ cells. © 2004 Wiley-Liss, Inc. [source]

Proliferation of progenitor cells in the adult rat brain correlates with the presence of vimentin-expressing astrocytes

GLIA, Issue 4 2001
Gérard Alonso
Abstract It is well established that proliferation of progenitor cells persists within the hippocampal dentate gyrus (DG) and the subventricular zone of the lateral ventricle (SVZ) in the adult brain. The aim of the present study was to determine whether the rate of cell proliferation within these germinative zones could be correlated to the occurrence of a particular glial environment. The cell proliferation marker bromodeoxyuridine (BrdU) was administrated to rats under different physiological and experimental conditions known to modify the rate of progenitor cell proliferation. Within both germinative zones, BrdU-labeled nuclei were associated with cell bodies immunostained for the neuronal marker polysialylated neural cell adhesion molecule, but not for the glial markers glial fibrillary acidic protein (GFAP) or vimentin (VIM). In all the rats examined, however, proliferating (BrdU-labeled) cells always exhibited close relationships with immature-like astrocytes that expressed both GFAP and VIM. There was a dramatic decrease of cell proliferation in the DG from both the aged rats and the corticosterone-treated adult rats that was correlated with a decreased expression of vimentin by the astrocytes present in this region. In contrast, both cell proliferation and vimentin expression were only slightly affected in the SVZ from these two treatment groups. Conversely, after either adrenalectomy or a surgical lesion through the lateral hippocampus, the increase in cell proliferation observed in the DG was correlated to the occurrence of an increased number of GFAP and VIM double immunostained structures in these regions. All together, these data suggest that immature-like astrocytes present in the germinative zones may provide a microenvironment involved in sustaining the proliferation of progenitor cells. GLIA 34:253,266, 2001. © 2001 Wiley-Liss, Inc. [source]

Victor Horsley's Contribution to Jacksonian Epileptology

EPILEPSIA, Issue 11 2005
Mervyn J. Eadie
Summary:,Purpose: To describe Victor Horsley's contribution to John Hughlings Jackson's understanding of the mechanisms involved in the generalization of convulsive epileptic seizures. Methods: I reviewed Horsley's writings and other relevant late 19th century medical literature. Results: Horsley's combination of strategically sited surgical lesions and cerebral cortex stimulation studies in experimental animals showed that, contrary to Hughlings Jackson's earlier belief, epileptic activity arising in one cerebral hemisphere had to spread to the contralateral hemisphere before bilateral convulsing could occur. Conclusions: On the basis of well-designed experiments, Horsley made a major contribution to the understanding of epileptic seizure propagation mechanisms. [source]

Surface Electrocardiographic Patterns and Electrophysiologic Characteristics of Atrial Flutter Following Modified Radiofrequency MAZE Procedures

Introduction: The radiofrequency MAZE is becoming a common adjunct to cardiac surgery in patients with atrial fibrillation. While a variety of postoperative arrhythmias have been described following the original Cox-MAZE III procedure, the electrophysiological characteristics and surgical substrate of post-radiofrequency MAZE flutter have not been correlated. We sought to determine the location, ECG patterns, and electrophysiological characteristics of post-radiofrequency MAZE atrial flutter. Methods: Nine consecutive patients with post-radiofrequency MAZE flutter presented for catheter ablation 9 ± 10 months after surgery. Results: Only one patient (11%) had an ECG appearance consistent with typical isthmus-dependent right atrial (RA) flutter. However, on electrophysiological study, 3/9 patients (33%) had typical right counter-clockwise flutter entrained from the cavo-tricuspid isthmus, despite description of surgical isthmus ablation. Six patients (67%) had left atrial (LA) circuits. These involved the mitral annulus in 5/6 cases (83%) despite description of surgical mitral isthmus ablation in the majority (60%). LA flutters had a shorter cycle length compared with RA flutters (253 ± 39 msec and 332 ± 63 msec respectively, P < 0.05). After a mean of 8 ± 4 months following ablation, 8/9 patients (89%) were in sinus rhythm. Conclusion: Up to one-third of post-radiofrequency MAZE circuits are typical isthmus-dependent RA flutters, despite a highly atypical surface ECG morphology. Therefore, diagnostic electrophysiological studies should commence with entrainment at the cavo-tricuspid isthmus in order to exclude typical flutter, regardless of the surface ECG appearance. Incomplete surgical lesions at the mitral and cavo-tricuspid isthmus likely predispose to the development of post-radiofrequency MAZE flutter. [source]

Lower genital tract lesions requiring surgical intervention in girls: Perspective from a developing country

Sebastian O Ekenze
Aim: To determine the spectrum, outcome of treatment and the challenges of managing surgical lesions of lower genital tract in girls in a low-resource setting. Method: Retrospective study of 87 girls aged 13-years and younger, with lower genital tract lesions managed between February 2002 and January 2007 at the University of Nigeria Teaching Hospital, Enugu, southeastern Nigeria. Clinical charts were reviewed to determine the types, management, outcome of treatment and management difficulties. Results: The median age at presentation was 1 year (range 2 days,13 years). Congenital lesions comprised 67.8% and acquired lesions 32.2%. The lesions included: masculinised external genitalia (24), vestibular fistula from anorectal malformation (23), post-circumcision labial fusion (12), post-circumcision vulval cyst (6), low vaginal malformations (6), labial adhesion (5), cloacal malformation (3), bifid clitoris (3) urethral prolapse (3), and acquired rectovaginal fistula (2). Seventy-eight (89.7%) had operative treatment. Procedure related complications occurred in 19 cases (24.4%) and consisted of surgical wound infection (13 cases), labial adhesion (4 cases) and urinary retention (2 cases). There was no mortality. Overall, 14 (16.1%) abandoned treatment at one stage or another. Challenges encountered in management were inadequate diagnostic facilities, poor multidisciplinary collaboration and poor patient follow up. Conclusion: There is a wide spectrum of lower genital lesion among girls in our setting. Treatment of these lesions may be challenging, but the outcome in most cases is good. High incidence of post-circumcision complications and poor treatment compliance may require more efforts at public enlightenment. [source]