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Biomedical subjects

Arthur L Day

Publications and source records attributed to Arthur L Day.

18 recordsLinked to original sources
PubMed2006

Neurosurgeons and their contributions to modern-day athletics: Richard C. Schneider Memorial Lecture.

Neurosurgeons in the last half-century have had considerable influence on modern-day athletics. In this article, the authors address the contributions made by neurosurgeons as clinician-scientists, particularly as these relate to the understanding and reduction of the incidence and severity of injury to the nervous system during athletic competition. American football has been a proving ground for the ability of the craniospinal axis to withstand and, in unfortunate cases, succumb to tremendous impact forces; in this way, it has served as a model for translational research and was the arena in which Dr. Richard Schneider made his greatest contributions to sports neurosurgery. Therefore, in his memory and in the spirit of the Schneider lectureship, the authors outline the notable contribution to modern-day athletics made by neurosurgeons as it applies to American football. Neurosurgeons have had considerable influence on reducing injury severity, and this cause has been championed by a few notable individuals whose efforts are discussed herein.

Athletic Injuries↗
PubMed2006

Lumbar spine injuries in athletes.

Lumbar spine injuries in athletes are not uncommon and usually take the form of a mild muscle strain or sprain. More severe injuries sustained by athletes include disc herniations, spondylolistheses, and various types of fracture. The recognition and management of these injuries in athletes involve the additional consideration that to return to play, the lumbar spine must be able to withstand forces similar to those that were injurious. The authors consider common lumbar spine injuries in athletes and discuss management principles for neurosurgeons that are relevant to this population.

Athletic Injuries↗
PubMed2005

17beta-Estradiol attenuates blood-brain barrier disruption induced by cerebral ischemia-reperfusion injury in female rats.

Disruption of blood-brain barrier (BBB), mediated through matrix metalloproteinases (MMPs), is a critical event during cerebral ischemia. While neuroprotective effects of estrogens have been well established in ischemic stroke models, the effects of estrogens on BBB integrity remain to be elucidated. In the present study, we determined effects of 17beta-estradiol (E2) on BBB disruption induced by transient focal cerebral ischemia and its effects on MMP2 and MMP9 activation. Transient cerebral ischemia was induced by middle cerebral artery (MCA) occlusion for 1 h followed by reperfusion in ovariectomized rats. E2 (100 microg/kg) or vehicle was administered 2 h before MCA occlusion. BBB integrity was determined by fluorescent detection of extravasated Evans blue. In separate experiments, effect of E2 on MMP2 and MMP9 expression and activation was determined by immunoblot and MMPs activity assay. E2 treatment prevented more than 50% and 30% of BBB disruption in the ischemic cortex and subcortex at 4 h after reperfusion, respectively. MMP2 and MMP9 expression was elevated at 2 h and peaked at 4 h after reperfusion in the ischemic cortex, which was markedly reduced by E2 treatment. E2 treatment also attenuated the increase of MMPs activity induced by ischemia-reperfusion injury. In conclusion, estrogens could attenuate BBB disruption induced by transient cerebral ischemia, by inhibition of MMP2 and MMP9 activation. Our results suggest an important role of estrogens as multiple targeting protectants against ischemic stroke on cellular as well as vascular components of central nervous system.

Animals↗
PubMed2005

Hippocampal progenitor cells express nestin following cerebral ischemia in rats.

This study addresses whether hippocampal progenitor cells express nestin following cerebral ischemia in rats. Cell counts within the hippocampal hilus were significantly greater following severe (eight-vessel occlusion) ischemia than following intermediate (four-vessel occlusion) ischemia (1527+/-87/mm2 vs. 918+/-71/mm2). Bromedeoxyuridine-positive cell counts were significantly higher with severe ischemia than with intermediate ischemia or in sham-operated animals, respectively (368+/-45, 43+/-14 and 7+/-1/mm2). In the eight-vessel occlusion group, 47+/-8/mm2 bromedeoxyuridine-labeled cells expressed nestin, significantly higher than in the four-vessel occlusion group and sham-operated animals (1+/-1 and 1+/-0/mm2, P<0.01 vs. eight-vessel occlusion, respectively). Confocal microscopy verified that a subset of the bromedeoxyuridine-positive cells expressed nestin. In conclusion, severe ischemia elicits nestin expression in hippocampal progenitor cells in rats.

Analysis of Variance↗
PubMed2005

Neuroendocrine mechanism for tolerance to cerebral ischemia-reperfusion injury in male rats.

Testosterone has been shown to exacerbate cerebral ischemia-reperfusion injury, which suggests that the well-known stress-induced testosterone reduction could be a protective response. We hypothesized that stress-induced testosterone reduction contributes to ischemia tolerance in cerebral ischemia-reperfusion injury in male rats. In intact male rats, stress was induced by brief anesthesia at 6 h before transient middle cerebral artery occlusion (MCAO). Testosterone levels were significantly decreased 6 h after stress. Testosterone reduction was associated with a 50% reduction in cerebral lesion volume in the stressed animals. Further, the stress-induced cerebral ischemia tolerance was eliminated by testosterone replacement in castrated males. Immunohistochemical staining showed that androgen receptors were up-regulated after cerebral ischemia-reperfusion injury and partially colocalized with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive cells in the parietal cortex and extensively colocalized in the caudate putamen. Heat shock protein 70 (Hsp70) and 90 (Hsp90) are involved in ischemia tolerance, and were not colocalized with TUNEL in the immunohistochemical staining, suggesting an antiapoptotic role of Hsp's. To determine the effect of testosterone on MCAO-induced Hsp70 and -90 expression, a testosterone replacement or withdrawal paradigm was used. Testosterone-replaced animals exhibited a decrease in Hsp expression, whereas testosterone withdrawal (mimicking the stress-induced testosterone suppression) normalized this deficit. In summary, stress-induced testosterone reduction contributes to ischemia tolerance in cerebral ischemia-reperfusion injury in males, which could be related to the loss of inhibition by testosterone of Hsp70 and -90 expression.

Animals↗
PubMed2005

Intraoperative awakening for vision examination during ophthalmic artery aneurysm clipping: technical case report.

OBJECTIVE AND IMPORTANCE: We present a case of a patient with an ophthalmic artery aneurysm in which the ophthalmic artery originated from the body of the aneurysm, requiring sacrifice of the ophthalmic artery to achieve complete aneurysm obliteration. We awakened the patient intraoperatively to assess optic nerve function after clipping and were able to confirm optic nerve function. Controlled intraoperative awakening proved a valuable adjunct to intraoperative angiography in determining the immediate consequences of sacrifice of the ophthalmic artery. CLINICAL PRESENTATION: The patient was a 55-year-old right-handed woman with a 3-month history of episodic blurriness in her left eye; imaging demonstrated an unruptured 5-mm left ophthalmic artery aneurysm in which the ophthalmic artery originated from the body of the aneurysm. INTERVENTION: Complete obliteration of the aneurysm required clip placement across the neck of the aneurysm, incorporating not only the aneurysm but also the ophthalmic artery. Aware that sacrifice of the ophthalmic artery was likely, we awakened the patient after clipping and before dural closure to evaluate her optic nerve function. Once fully awake, the patient was able to execute simple commands and conclusively confirm light perception in both of her eyes. She was then reanesthetized, and intraoperative angiography showed successful aneurysm obliteration and parent artery patency. CONCLUSION: The ophthalmic artery can be sacrificed during aneurysm clipping without loss of vision in many cases, most likely because of adequate collateral filling from the external carotid artery. Certainty about the visual consequences of sacrifice of the ophthalmic artery, however, is difficult to obtain preoperatively or intraoperatively. Intraoperative awakening for evaluation of optic nerve function served as a useful technique to assess the acute results of interruption of ophthalmic artery flow in this case.

Aneurysm↗
PubMed2004

Increased severity of acute cerebral ischemic injury correlates with enhanced stem cell induction as well as with predictive behavioral profiling.

An 8-vessel-occlusion (8VO) method was developed to compare with the conventional 4-vessel-occlusion (4VO) in hippocampal ischemic damage and progenitor cell induction 10 days following ischemia in female rats. Eight posture-relevant tests were performed following ischemia to correlate grades of postural abnormality with the histological outcome. The total hippocampal living cell ratio including 7 hippocampal subregions in 8VO group (n=11) was much lower than that in 4VO group (n=10, 51+/-5% vs. 78+/-4, p<0.01). In 4VO group, BrdU positive cells were mainly located in the subgranular zone (SGZ) with a count of 54+/-20/mm2 (7micro-thick slice), comparable to the maximal level following global ischemia in male gerbils and rats reported so far referring to slice-thickness differences (50-60 micro-thick slices). Similarly, nestin-bearing cells were 29+/-11/ mm2. In 8VO group, BrdU and nestin positive cells increased by 10 times. Triple staining of BrdU, nestin and DAPI demonstrated that BrdU-immunoreactivity was extensively distributed in the hippocampal hilus while the nestin was mainly located along the SGZ. Most of nestin labeling was not co-localized with the BrdU, indicating that establishment of these cells might precede BrdU injections (8 and 9d post ischemia). Behavioral scores were much greater for 8VO group than for 4VO group and composite postural scores well correlated with the hippocampal cell loss. In conclusion, severe ischemia correlates with vigorous induction of the hippocampal progenitor cells in rats while behavioral profiling of posture changes permits prediction of severity of damage.

Animals↗
PubMed2003

17beta-Estradiol extends ischemic thresholds and exerts neuroprotective effects in cerebral subcortex against transient focal cerebral ischemia in rats.

Neuroprotective effects of estrogens are demonstrated consistently in the cerebral cortex, but not in subcortical areas. In the present study, transient middle cerebral artery occlusions (MCAO) were induced for various duration, and protective effects of estrogen treatment on the cerebral cortex and subcortex were evaluated. MCAO was induced for 30, 40 or 60 min in ovariectomized rats. Animals were treated with 17beta-estradiol (E2) or vehicle (OVX) 2 h before MCAO and sacrificed 24 h after the indicated duration of MCAO. Ischemic lesion was evaluated by 2,3,5-triphenyltetrazolium chloride staining, hematoxylin and eosin staining, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. E2 treatment reduced the magnitude and delayed the appearance of the total ischemic lesion area and largely prevented TUNEL staining in the cortex. In the subcortex, E2 treatment prevented the ischemic lesion in the 30-min group, reduced lesion area in the 40-min group, but had no effect on ischemic lesion area in the 60-min group. E2 treatment significantly decreased apoptotic cell number in the subcortical area at 30 and 40 min, but not at 60 min of MCAO. This study demonstrated that estrogen treatment can protect the cerebral subcortex in a severity-dependent manner, suggesting that the lack of protective effects of estrogen treatment in the subcortex is not due to the lack of estrogen receptors. Further, this study indicates that estrogens could be used as a neuroprotectant to prolong the therapeutic window of thrombolysis and prolong the time of cerebral circulation intervention for neurosurgical procedure.

Animals↗
PubMed2003

Spontaneous fusiform middle cerebral artery aneurysms: characteristics and a proposed mechanism of formation.

OBJECT: The goal of this study was to identify the origins of spontaneous fusiform middle cerebral artery (MCA) aneurysms. METHODS: One hundred two cases of spontaneous fusiform MCA aneurysms were reviewed, including 40 from the authors' institutions and 62 identified from the literature. The mean age at symptom onset was 38 years, and the male/female ratio was 1.4:1. At presentation, the MCA lumen was stenosed or occluded in 12 patients, focally dilated in 57, and appeared "serpentine" in 33. Most lesions originated from the M1 or M2 segments, and most (80%) presented with nonhemorrhagic symptoms or were discovered incidentally. The presenting clinical features correlated with morphological findings in the aneurysms, which could be observed to progress from a small focal dilation or vessel narrowing to a serpentine channel. Hemorrhage was the most common presentation in small lesions; the incidence of bleeding progressively diminished with larger lesions. Patients with stenoses or occluded vessels most often presented with ischemic symptoms, and occasionally with hemorrhage. Giant focal dilations or serpentine aneurysms were rarely associated with acute bleeding; clinical presentation was most often prompted by mass effect or thromboembolic stroke. CONCLUSIONS: Analysis of results after various treatments indicates that for symptomatic lesions, therapies that reverse intraaneurysmal blood flow and augment distal cerebral perfusion are associated with better outcomes than other strategies, including conservative management. Based on the spectrum of clinical, pathological, neuroimaging, and intraoperative findings, dissection is proposed as the underlying cause of these lesions.

Adolescent↗
PubMed2002

Proestrus levels of estradiol during transient global cerebral ischemia improves the histological outcome of the hippocampal CA1 region: perfusion-dependent and-independent mechanisms.

We conducted this study to determine whether high physiological levels of estradiol (proestrus) could protect the hippocampal CA1 neurons following transient global ischemia. Ovariectomized or ovary-intact female rats were subjected to 20 min of ischemia and allowed to survive for 96 h. Estradiol was administered subcutaneously in a group of ovariectomized rats 24 h before ischemia induction. Ending serum estrogen levels were correlated to cerebral blood flow (CBF), histologic assessment and immunofluorescent caspase-3 active peptide (C-3AP) positive cell count. Estradiol administration significantly improved CBF in the hippocampus (compared with intact or ovariectomized rats) but not in the parietal cortex. No significant differences in CBF between intact or ovariectomized rats were noted. Estradiol administration maintained serum levels of the steroid in estradiol-treated rats-about 10 times that of intact animals and more than 20 times that of ovariectomized animals. Morphologically, live cell counts in estradiol-treated rats were significantly higher than in intact or ovariectomized rats. Live cell counts were also significantly higher in intact than ovariectomized rats. C-3AP positive cell counts were much higher in ovariectomized rats than in intact and estradiol-treated rats. In conclusion, proestrus levels of 17beta-estradiol protect hippocampal CA1 neurons against transient global ischemia, through mechanisms that appear to involve improvement of perfusion and inhibition of caspase-3 activity.

Animals↗
PubMed2002

Extracranial-intracranial vein graft bypass for giant intracranial aneurysm surgery for pediatric patients: two technical case reports.

OBJECTIVE AND IMPORTANCE: Herein we describe two cases of extracranial-intracranial vein graft bypasses for the treatment of giant intracranial aneurysms in prepubertal pediatric patients. One patient is, we think, the youngest patient reported in the literature to have been successfully treated in such a manner, with a good long-term outcome. Such grafts seem to enlarge longitudinally during the growth spurt, making such techniques reasonable long-term therapeutic options for the management of complex intracranial aneurysms in pediatric patients. CLINICAL PRESENTATION: Patient 1, a 13-year-old boy, presented with headaches and rapidly progressive right cavernous sinus syndrome. Computed tomography and cerebral angiography revealed a giant, fusiform, right intracavernous internal carotid artery aneurysm. Patient 2, a 23-month-old girl, was discovered to harbor an asymptomatic, recurrent, giant, fusiform, left M1 middle cerebral artery aneurysm 1 year after presenting with seizures related to subarachnoid hemorrhage from the aneurysm, for which she had been treated with clipping and an M2-M2 anastomosis. INTERVENTION: Both patients underwent craniotomies, with sacrifice of the proximal parent vessel (the distal cervical internal carotid artery and the proximal middle cerebral artery, respectively), combined with cerebral revascularization through extracranial-intracranial saphenous vein bypass grafts. Both patients experienced excellent long-term clinical outcomes, have undergone significant growth, and exhibit excellent long-term graft patency and aneurysm obliteration. CONCLUSION: These two cases highlight the safety and efficacy of extracranial-intracranial vein graft bypasses among prepubertal pediatric patients. The indications for bypass procedures to treat giant intracranial aneurysms are discussed, and the technical aspects of maximizing vein bypass graft patency are reviewed.

Adolescent↗
PubMed2002

Testosterone increases neurotoxicity of glutamate in vitro and ischemia-reperfusion injury in an animal model.

Increasing evidence has demonstrated striking sex differences in the outcome of neurological injury. Whereas estrogens contribute to these differences by attenuating neurotoxicity and ischemia-reperfusion injury, the effects of testosterone are unclear. The present study was undertaken to determine the effects of testosterone on neuronal injury in both a cell-culture model and a rodent ischemia-reperfusion model. Glutamate-induced HT-22 cell-death model was used to evaluate the effects of testosterone on cell survival. Testosterone was shown to significantly increase the toxicity of glutamate at a 10 microM concentration, whereas 17beta-estradiol significantly attenuated the toxicity at the same concentration. In a rodent stroke model, ischemia-reperfusion injury was induced by temporal middle cerebral artery occlusion (MCAO) for 1 h and reperfusion for 24 h. To avoid the stress-related testosterone reduction, male rats were castrated and testosterone was replaced by testosterone pellet implantation. Testosterone pellets were removed at 1, 2, 4, or 6 h before MCAO to determine the duration of acute testosterone depletion effects on infarct volume. Ischemic lesion volume was significantly decreased from 239.6 +/- 25.9 mm(3) in control to 122.5 +/- 28.6 mm(3) when testosterone pellets were removed at 6 h before MCAO. Reduction of lesion volume was associated with amelioration of the hyperemia during reperfusion. Our in vitro and in vivo studies suggest that sex differences in response to brain injury are partly due to the consequence of damaging effects of testosterone.

Animals↗
PubMed2002

Neuroprotective effects of a novel non-receptor-binding estrogen analogue: in vitro and in vivo analysis.

BACKGROUND AND PURPOSE: Although estrogens are neuroprotective, hormonal effects limit their clinical application. Estrogen analogues with neuroprotective function but lacking hormonal properties would be more attractive. The present study was undertaken to determine the neuroprotective effects of a novel 2-adamantyl estrogen analogue, ZYC3. METHODS: Cytotoxicity was induced in HT-22 cells by 10 mmol/L glutamate. 17beta-Estradiol (E2) or ZYC3 was added immediately before the exposure to glutamate. Cell viability was determined by calcein assay. The binding of E2 and ZYC3 to human alpha (ERalpha) and beta (ERbeta) estrogen receptors was determined by ligand competition binding assay. Ischemia/reperfusion injury was induced by temporary middle cerebral artery occlusion (MCAO). E2 or ZYC3 (100 microg/kg) was administered 2 hours or immediately before MCAO, respectively. Infarct volume was determined by 2,3,5-triphenyltetrazolium chloride staining. Cerebral blood flow was recorded during and within 30 minutes after MCAO by a hydrogen clearance method. RESULTS: ZYC3 significantly decreased toxicity of glutamate with a potency 10-fold that of E2. ZYC3 did not bind to either ERalpha or ERbeta. Infarct volume was significantly reduced to 122.4+/-17.6 and 83.1+/-19.3 mm(3) in E2 and ZYC3 groups, respectively, compared with 252.6+/-15.6 mm(3) in the ovariectomized group. During MCAO, both E2 and ZYC3 significantly increased cerebral blood flow in the nonischemic side, while no significant differences were found in the ischemic side. However, E2 and ZYC3 significantly increased cerebral blood flow in both sides within 30 minutes after reperfusion. CONCLUSIONS: Our study shows that ZYC3, a non-receptor-binding estrogen analogue, possesses both neuroprotective and vasoactive effects, which offers the possibility of clinical application for stroke without the side effects of estrogens. It also suggests that both the neuroprotective and vasoactive effects of estrogen are receptor independent.

Adamantane↗
PubMed2002

Distal posterior inferior cerebellar artery aneurysms: clinical features and management.

OBJECT: Aneurysms located on the distal portion of the posterior inferior cerebellar artery (PICA) are uncommon, and their underlying pathology, natural history, and clinical management are poorly understood. To clarify these lesions more fully, the authors undertook a retrospective analysis of the clinical features and management results of 22 distal PICA aneurysms in 20 consecutive patients treated at one institution by the same surgeon during the past decade. METHODS: The series included 10 men and 10 women (mean age at presentation 51 years). Nine patients presented with only subarachnoid and/or intraventricular hemorrhage (median Hunt and Hess Grade II). In seven patients intracerebellar hemorrhage was also found; two patients presented with pressure effects and two hemorrhages were incidentally discovered. Prominent comorbidities included cigarette smoking (50%) and hypertension (50%). The 13 saccular and nine fusiform distal PICA aneurysms were distributed on the following segments of the PICA: lateral medullary (seven lesions), tonsillomedullary (five lesions), telovelotonsillar (five lesions), and cortical (five lesions). Six oases were associated with cerebellar arteriovenous malformations. Skull-base and far-lateral transcondylar surgical approaches were used to secure the aneurysms in 86% of cases, either by direct clipping (13 lesions), vessel sacrifice (four lesions), or vessel sacrifice plus bypass (two lesions). Two aneurysms were treated using endovascular PICA ablation. Overall outcome at hospital discharge was excellent or good in 70% of cases. At long-term follow up (100% of patients, mean 123 days), an excellent or good outcome had been achieved in 85% of cases. CONCLUSIONS: Depending on the PICA segment that was affected, variations in clipping strategies and surgical exposures aimed at the PICA branch and main trunk preservation were major contributors to good long-term results.

Adult↗
PubMed2002

The neurosurgeon in sport: awareness of the risks of heatstroke and dietary supplements.

THE SCIENCE OF fluid replacement in athletic training, particularly with regard to American football players, has advanced during the past 3 decades. This advance has resulted in substantial decreases in heatstroke-related deaths during summer training sessions. Recent trends in football heatstroke fatalities toward significant increases may, in part, be attributable to or aggravated by the use of dietary supplements. Credible scientific evidence has been found that amphetamine derivatives and the ergonomic aid creatine may contribute to subclinical dehydration and heatstroke in selected individuals. Caution is urged in the education and evaluation of football players who train during the hot summer months.

Amphetamines↗