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Biomedical subjects

S Amin-Hanjani

Publications and source records attributed to S Amin-Hanjani.

At least 19 recordsLinked to original sources
PubMed2005

Long-term follow-up of giant serpentine MCA aneurysm treated with EC-IC bypass and proximal occlusion.

Giant serpentine aneurysms are a rare but important subset of giant aneurysms, with unique management considerations. We present long-term follow-up clinical and imaging features of a giant serpentine middle cerebral artery lesion treated with extracranial-intracranial bypass and proximal occlusion more than a decade earlier. Calcification of the obliterated aneurysm sac and durability of this management strategy are demonstrated.

Adolescent↗
PubMed2001

BID mediates neuronal cell death after oxygen/ glucose deprivation and focal cerebral ischemia.

Mitochondria and cytochrome c release play a role in the death of neurons and glia after cerebral ischemia. In the present study, we investigated whether BID, a proapoptotic promoter of cytochrome c release and caspase 8 substrate, was expressed in brain, activated after an ischemic insult in vivo and in vitro, and contributed to ischemic cell death. We detected BID in the cytosol of mouse brain and primary cultured mouse neurons and demonstrated, by using recombinant caspase 8, that neuronal BID also is a caspase 8 substrate. After 2 h of oxygen/glucose deprivation, BID cleavage was detected in neurons concurrent with caspase 8 activation but before caspase 3 cleavage. Bid(-/-) neurons were resistant to death after oxygen/glucose deprivation, and caspase 3 cleavage was significantly reduced; however, caspase 8 cleavage did not differ from wild type. In vivo, BID was cleaved 4 h after transient middle cerebral artery occlusion. Infarct volumes and cytochrome c release also were less in Bid(-/-) mice (-67% and -41%, respectively) after mild focal ischemia. These findings suggest that BID and the mitochondrial-amplification pathway promoting caspase activation contributes importantly to neuronal cell death after ischemic insult.

Animals↗
PubMed2001

Temporal clustering of hemorrhages from untreated cavernous malformations of the central nervous system.

OBJECTIVE: Hemorrhages from cerebral cavernous malformations (CMs) sometimes seem to occur in closely spaced "clusters" interspersed with long hemorrhage-free intervals. Clustering of hemorrhages could affect retrospective assessments of radiosurgery efficacy in prevention of CM rehemorrhage. However, this empirical observation had not been tested quantitatively. To test whether CM hemorrhages tend to cluster, we reviewed pretreatment rebleeding rates after a first symptomatic hemorrhage in CM patients who later underwent surgery or radiosurgery. METHODS: We performed a retrospective review of 141 patients with CMs who presented with clinically overt hemorrhage, and who subsequently underwent surgery or proton beam radiosurgery during an 18-year period. Statistical models were used to analyze all events per person and identify potential variation in rebleeding risk with time after a previous hemorrhage. RESULTS: Sixty-three of 141 patients experienced a second hemorrhage before treatment; 16 had additional hemorrhages. Five hundred thirty-eight patient years elapsed between first hemorrhages and treatment. The cumulative incidence of a second hemorrhage after the first CM hemorrhage was 14% after 1 year and 56% after 5 years. During the first 2.5 years after a hemorrhage, the monthly rehemorrhage hazard was 2%. The risk then decreased spontaneously to less than 1% per month, which represents a 2.4-fold decline (P < 0.001). Rehemorrhage rates were higher in younger patients (P < 0.01), but not in females or in patients with deep lesions. Shorter intervals between successive hemorrhages did not predict higher subsequent rehemorrhage risk. CONCLUSION: The rehemorrhage rate from untreated CMs is high initially, and it decreases 2 to 3 years after a previous hemorrhage. This hazard pattern generates the observed temporal clustering of hemorrhages from untreated CMs.

Adolescent↗
PubMed2001

Mevastatin, an HMG-CoA reductase inhibitor, reduces stroke damage and upregulates endothelial nitric oxide synthase in mice.

BACKGROUND AND PURPOSE: The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) lower serum cholesterol and decrease the incidence of stroke and cardiovascular disease. There is growing evidence that statins exert some of their beneficial effects independent of cholesterol lowering. Indeed, we have previously demonstrated that chronic simvastatin administration upregulates endothelial nitric oxide synthase (eNOS), resulting in more functional protein, augmentation of cerebral blood flow, and neuroprotection in a murine model of cerebral ischemia. In this report we examined whether another member of the statin family shared these effects and whether eNOS upregulation is sustained with longer treatment. METHODS: Mevastatin (2 mg/kg or 20 mg/kg per day) was administered to 18- to 22-g male mice for 7, 14, or 28 days before 2-hour middle cerebral artery occlusion with the use of the filament model (n=9 to 12). Neurological deficits and cerebral infarct volumes were assessed at 24 hours. Arterial blood pressure and gases, relative cerebral blood flow, and blood cholesterol levels were monitored in a subset of animals (n=5). Absolute cerebral blood flow was measured by the [(14)C]iodoamphetamine indicator fractionation technique (n=6). eNOS mRNA and protein levels were determined. RESULTS: Mevastatin increased levels of eNOS mRNA and protein, reduced infarct size, and improved neurological deficits in a dose- and time-dependent manner. Greatest protection was seen with 14- and 28-day high-dose treatment (26% and 37% infarct reduction, respectively). Cholesterol levels were reduced only after 28 days of treatment and did not correlate with infarct reduction. Baseline absolute cerebral blood flow was 30% higher after 14-day high-dose treatment. CONCLUSIONS: Chronic prophylactic treatment with mevastatin upregulated eNOS and augmented cerebral blood flow. These changes occurred in the absence of changes in serum cholesterol levels, were sustained for up to 1 month of treatment, and resulted in neuroprotection after middle cerebral artery occlusion.

Animals↗
PubMed2000

Dual role of caspase-11 in mediating activation of caspase-1 and caspase-3 under pathological conditions.

Caspase-11, a member of the murine caspase family, has been shown to be an upstream activator of caspase-1 in regulating cytokine maturation. We demonstrate here that in addition to its defect in cytokine maturation, caspase-11-deficient mice have a reduced number of apoptotic cells and a defect in caspase-3 activation after middle cerebral artery occlusion (MCAO), a mouse model of stroke. Recombinant procaspase-11 can autoprocess itself in vitro. Purified active recombinant caspase-11 cleaves and activates procaspase-3 very efficiently. Using a positional scanning combinatorial library method, we found that the optimal cleavage site of caspase-11 was (I/L/V/P)EHD, similar to that of upstream caspases such as caspase-8 and -9. Our results suggest that caspase-11 is a critical initiator caspase responsible for the activation of caspase-3, as well as caspase-1 under certain pathological conditions.

Animals↗
PubMed2000

Neuroprotection mediated by changes in the endothelial actin cytoskeleton.

Cerebral blood flow is regulated by endothelium-derived nitric oxide (NO), and endothelial NO synthase-deficient (eNOS-deficient; eNOS(-/-)) mice develop larger cerebral infarctions following middle cerebral artery (MCA) occlusion. We report that disruption of Rho-mediated endothelial actin cytoskeleton leads to the upregulation of eNOS expression and reduces the severity of cerebral ischemia following MCA occlusion. Mice treated with the Rho inhibitor Clostridium botulinum C3 transferase (10 microgram/d) or the actin cytoskeleton disrupter cytochalasin D (1 mg/kg) showed a two- to fourfold increase in vascular eNOS expression and activity. This increase in eNOS expression was not due to increases in eNOS gene transcription, but to prolongation of eNOS mRNA half-life from 10 +/- 3 hours to 24 +/- 4 hours. Indeed, endothelial cells overexpressing a dominant-negative Rho mutant (N19RhoA) exhibited decreased actin stress fiber formation and increased eNOS expression. Inhibition of vascular Rho guanosine-5'-triphosphate binding activity by the 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor simvastatin increased cerebral blood flow to ischemic regions of the brain, and mice treated with simvastatin, C3 transferase, or cytochalasin D showed smaller cerebral infarctions following MCA occlusion. No neuroprotection was observed with these agents in eNOS(-/-) mice. These findings suggest that therapies which target the endothelial actin cytoskeleton may have beneficial effects in ischemic stroke.

Actins↗
PubMed1999

Hypertensive encephalopathy as a complication of hyperdynamic therapy for vasospasm: report of two cases.

OBJECTIVE AND IMPORTANCE: After developing subarachnoid hemorrhage, patients may deteriorate from a variety of well-known causes, including rebleeding, hydrocephalus, and vasospasm. Many patients now undergo empirical hyperdynamic vasospasm therapy with hypervolemia, induced hypertension, and nimodipine. CLINICAL PRESENTATION: We report two cases of iatrogenic hypertensive encephalopathy occurring during hyperdynamic therapy for cerebral vasospasm after subarachnoid hemorrhage. Hypertensive encephalopathy is a syndrome of rapidly evolving generalized or focal cerebral symptoms occurring in the setting of severe hypertension, which is reversible with antihypertensive therapy. INTERVENTION: The syndrome can be diagnosed in the appropriate clinical setting with computed tomographic or magnetic resonance imaging that demonstrates characteristic findings. In both cases, decreasing the blood pressure resulted in neurological improvement. CONCLUSION: In the setting of induced hypertensive/hypervolemic therapy for vasospasm, hypertensive encephalopathy should be considered as a potentially reversible cause of delayed neurological decline.

Aged↗
PubMed1999

Overall surgical results of occult vascular malformations.

Surgical experience with angiographically occult vascular malformations, specifically cavernous malformations (CMs), has increased substantially over recent years. CMs are generally well-circumscribed, low-pressure vascular lesions amenable to resection. Overall, results obtained with operative management have been favorable; however, the location of the lesion impacts significantly on the outcome and morbidity of surgery, with those located within deep and brain stem regions carrying a higher incidence of persistent neurologic complications. As knowledge emerges regarding the long-term natural history of these lesions, the role of operative intervention in cases where surgical morbidity is high will become better defined.

Adolescent↗
PubMed1998

Risks of surgical management for cavernous malformations of the nervous system.

OBJECTIVE: As more information evolves regarding the natural history of cavernous malformations (CMs), the risks of operative intervention must be balanced against nonoperative management. In an attempt to better delineate the surgical risks for operable CMs, we undertook a retrospective analysis of 94 patients with 97 CMs surgically excised at the Massachusetts General Hospital. METHODS: Data regarding surgical complications and outcome measures, including neurological status and seizure outcome, were analyzed. RESULTS: The incidence of transient neurological morbidity was 20.6%, but only 4 of the 97 operations (4.1%) resulted in persistent disabling neurological complications and 2 (2.1 %) in nondisabling deficits. There was no operative mortality. Brain stem lesions (n=14) were associated with the highest incidence of neurological complications, both transient and persistent (odds ratio, 4.8; 95% confidence interval, 1.5-15.7). The overall neurological outcome was excellent or good in 89.7% of all lesions: 96.8% of lobar CMs (n=63), 64.2% of brain stem CMs (n=14), 87.5% of cerebellar CMs (n=8), 100% of cranial nerve CMs (n=4), and 75% of spinal cord CMs (n=8). Patients with brain stem and spinal cord CMs were in poorer preoperative neurological condition than were patients with CMs in other locations and therefore had a significantly reduced level of function after surgery (P < 0.01). There was improvement in 35.7% of the patients with brain stem lesions and 62.5% of the patients with spinal cord lesions after surgery. In the 38 patients presenting with seizures, 97% were seizure-free after surgery. CONCLUSION: The risks of operative management of CMs varies based on location. When evaluating patients with operable CMs for surgery, the incidence of complications as well as final neurological outcome should be carefully weighed against the existing knowledge of the natural history of lesions managed expectantly.

Adolescent↗
PubMed1998

Stereotactic radiosurgery for cavernous malformations: Kjellberg's experience with proton beam therapy in 98 cases at the Harvard Cyclotron.

OBJECTIVE: The lack of treatment options for surgically inaccessible cavernous malformations has made radiosurgery a possible alternative to conservative management. The few previous reports of radiosurgical efficacy have been limited by small numbers, short follow-up, or lack of attention to the full spectrum of end points, including neurological disability. In an attempt to elucidate the risk-to-benefit ratio of radiosurgery for cavernous malformations, we undertook a retrospective analysis of of 95 patients with 98 lesions treated by the late Raymond N. Kjellberg. METHODS: Patients were followed for an average of 5.4 years (range, 0.3-12.3 yr), and data regarding hemorrhage, seizure, neurological disability, and incidence of radiation-induced complications were gathered. RESULTS: The analysis revealed a drop in annual hemorrhage rates from 17.3% per lesion per year before treatment to 4.5% per lesion per year after a latency period of 2 years. Improvement in seizure control was evident. However, a 16% incidence of permanent neurological deficit and a 3% mortality rate were attributable to radiographically confirmed radiation-induced complications. Neurological disability scores, measured by the modified Rankin disability scale, indicated a significant decline in neurological functioning during the follow-up interval, a result of the combined effects of radiation-related injury, hemorrhage, and clinical progression of the lesion. CONCLUSION: We conclude that although radiosurgery does seem to reduce hemorrhage, there is potential for complications and continued lesion progression after radiosurgery. These risks and benefits must be carefully balanced against the natural history of untreated lesions if the use of radiosurgery is considered.

Adolescent↗
PubMed1998

Familial intracranial arteriovenous malformations. Case report and review of the literature.

Familial intracranial arteriovenous malformations (AVMs) are rare. We describe a father and son both presenting in childhood with cerebral AVMs. Both patients underwent successful surgical extirpation of the AVM. Familial AVMs present at a young age and tend to be multiple, as was the case in one of our patients. Imaging of asymptomatic family members may detect previously undiagnosed AVMs, and we recommend screening of the relatives of patients with a strong family history of such lesions.

Adolescent↗
PubMed1997

Treatment of dissecting basilar artery aneurysm by flow reversal.

Dissecting aneurysm of the basilar artery is a rare but increasingly recognized entity, with a frequently fatal or morbid outcome. Unlike the well established proximal occlusion and trapping approaches to vertebral artery dissections, surgical intervention for basilar lesions has been limited to wrapping techniques for arterial wall reinforcement. We report a case of midbasilar dissecting aneurysm successfully treated by clipping the proximal basilar artery below the level of the anterior inferior cerebellar arteries, allowing retrograde flow via the posterior communicating arteries to provide continued basilar perfusion. With the growing recognition of basilar dissection and pseudoaneurysm formation there is a need for improved therapeutic options. We suggest that definitive treatment can be achieved using the principle of proximal occlusion and flow reversal, and review the pertinent literature on basilar artery dissection.

Aortic Dissection↗
PubMed1996

Impaired mobilization of intracellular calcium in neonatal platelets.

Abnormalities in platelet functions including aggregation and the release reaction have long been recognized to be present in neonatal platelets. Because calcium is an important mediator of many platelet functions, we have investigated the mobilization of calcium in neonatal platelets. All umbilical cord blood samples were obtained from healthy, full term gestations. Changes in cytoplasmic calcium levels were monitored using Fura-2 as a fluorescent probe. Fura-2-loaded washed platelets were stimulated with the agonists collagen (2 micrograms/mL) or thrombin (1.0 U/mL). When compared with adult controls, intracellular calcium release in the platelets of the neonate was significantly impaired in response to these agonists. Mean levels for calcium release in adults versus neonates in response to collagen were 168 +/- 120 nM (+/-SD, n = 10), and 61 +/- 69 nM (n = 7, p < 0.05). A decrease in response to thrombin was also observed [1296 +/- 503 nM (n = 8) in adults versus 603 +/- 482 nM (n = 7) in neonates, p < 0.025]. Results similar to those observed with unpaired neonatal and adult platelets were also obtained when neonatal platelets (n = 5) were compared with their paired maternal controls. In further studies, we have documented that the calcium content of the dense tubular system was normal in the neonatal platelet, indicating that the observed impairment in calcium mobilization in the neonate was not due to a decrease in calcium stores. The previously documented abnormalities in neonatal platelet function appear to be due to the impaired mobilization of this important intracellular mediator.

Adult↗
PubMed1995

Pyometra after endometrial resection and ablation.

BACKGROUND: Hysteroscopic endometrial ablation is increasingly accepted as a safe means of controlling excessive uterine bleeding. CASE: A 47-year-old woman underwent endometrial resection and ablation for menorrhagia and subsequently developed pyometra and bacteremia. Placement of an intrauterine drain and intravenous antibiotic therapy led to full recovery. CONCLUSION: Postoperative pyometra occurred after endometrial resection and ablation, a procedure reported to have few complications. To our knowledge, this has not been reported before.

Anti-Bacterial Agents↗
PubMed1994

Incidence of actinomycosis associated with intrauterine devices.

The incidence of intrauterine device (IUD)-associated cervicovaginal actinomycosis was evaluated. Papanicolaou-stained cervicovaginal smears from 1,520 women with IUDs were reviewed for the presence of Actinomyces-like organisms. The overall colonization rate was 11.4%. The colonization rates for the Progestasert, plastic IUDs and copper IUDs were 14.3%, 10.8% and 6.69%, respectively. The colonization rate appeared to increase with the duration of IUD use. The relatively high cervicovaginal Actinomyces colonization rate suggests that all patients with IUDs should undergo annual cytologic smears, with specific attention given to the presence of Actinomyces-like organisms.

Actinomyces↗
PubMed1993

Moyamoya disease in pregnancy: a case report.

Moyamoya disease is a rare condition characterized by narrowing and occlusion of the internal carotid arteries. The disease usually presents as alteration of consciousness caused by intracranial hemorrhage. We describe a case of moyamoya disease presenting as seizures in a pregnant patient. The characteristic angiographic appearances and plan of management are described.

Adult↗
PubMed1992

Cold therapy in the management of postoperative cesarean section pain.

Sixty-two patients were randomized to receive either localized cold therapy to the cesarean section incision or routine postoperative care. Evaluation of the amount of analgesia requested, infection rate, and length of hospital stay did not show a significant difference between the two groups. There is no objective evidence to show that the use of cold therapy in postoperative cesarean section pain relief is beneficial.

Cesarean Section↗