Vittorio Silvani

Bioenergetics of different brain areas after experimental subarachnoid hemorrhage in rats.

We studied energy metabolism after experimental subarachnoid hemorrhage in rats. Four different cerebral areas were tested: frontal cortex, occipital cortex, hippocampus, and brainstem. Vmax of the following enzymatic activities was evaluated: in the homogenate: hexokinase, phosphofructokinase, and lactate dehydrogenase for the glycolytic pathway, and glucose-6-phosphate dehydrogenase for the hexose monophosphate shunt; in the purified nonsynaptic mitochondria: NAD+-isocitrate dehydrogenase, citrate synthase, and succinate dehydrogenase for the Krebs cycle, and cytochrome oxidase for the electron transfer chain. We also evaluated some parameters related to the respiration of nonsynaptic mitochondria (State 3, State 4, uncoupled state, respiratory control ratio, and ADP:O ratio). Subarachnoid hemorrhage did not significantly affect Vmax of the enzymatic activities related to anaerobic and aerobic metabolism; however, mitochondrial respiration was affected, particularly in the presence of NADH-producing substrates (glutamate + malate).

Arachidonic acid metabolic profiles in human meningiomas and gliomas

We determined arachidonic acid (AA) cyclooxygenase metabolic profiles in specimens of human intracranial tumors (gliomas and meningiomas) and, when available, normal brain tissue. Samples were collected at surgery and immediately frozen in liquid nitrogen. The five stable metabolites of AA (PGE2, PGD2, PGF2α, 6-keto-PGF1α and TXB2) were measured by high-resolution gas chromatography-mass spectrometry after ex vivo metabolism of endogenous AA by tissue homogenates. The absolute amounts of AA metabolites varied widely between samples, though meningiomas and gliomas showed characteristic profiles. Compared to the slow-growing benign meningiomas, the rapidly-growing infiltrating gliomas had higher synthesis of TXA2 (reported as a procancer metabolite) and lower synthesis of PGD2 and PGI2 (reported as anticancer metabolites). A higher overall synthesis capacity, preferentially toward TXA2, was found in glioblastomas than in nonpathological brain tissue.

Ploidy and Proliferative Activity of Human Brain Tumors

Ploidy and proliferative characteristics were estimated by flow cytometry of the nuclear DNA content of 92 human brain tumors. Samples were frozen at -20 degrees C immediately after surgery and single cell suspensions were obtained with a mechanical dissociation technique. Propidium iodide was employed for nuclear DNA staining. Human normal brain tissue was used as internal diploid reference standard. 86% of benign tumors had unimodal DNA distribution with a DNA index (DNA I = modal channel of the G0/1 peak of the studied population/modal channel of the G0/1 peak of the normal brain) usually within the diploid or near-diploid range. 14.0% had aneuploidy, with an additional cell peak having a median DNA I of 1.60. Among malignant tumors, these figures were 61.2 and 38.8% (p less than 0.001). The percentage of S phase cells was higher in malignant (median = 3.6) than in benign tumors (median = 2.0, p less than 0.01), without correlation to histological tumor subtype. Flow cytometry appears to be a useful method for evaluating differences in DNA distribution in tumors of the central nervous system.

Experimental subarachnoid hemorrhage : lipid peroxidation and Na+, K+-ATPase in different rat brain areas

Subarachnoid hemorrhage (SAH) was produced in Sprague Dawley rats by injection of 0.30 mL of autologous arterial blood into the cisterna magna. Tissue lipid peroxide, quantified as thiobarbituric acid reactive material (TBAR), and Na+,K(+)-ATPase activity were assayed in three different rat brain areas (cerebral cortex, hippocampus, and brain stem) of sham-operated rats and in four hemorrhagic rat groups at 30 min, 1 h, 6 h, and 2 d after SAH. Na+,K(+)-ATPase activity decreased in the cerebral cortex at 30 min, 1 h, and 6 h and in the brain stem at 1 h after SAH induction, whereas enzymatic activity was unchanged in the hippocampus. There was no evident difference in lipid peroxide content between sham-operated animals and hemorrhagic animals. These results indicate that little modifications in lipid peroxidative process (as expressed in TBAR) are not responsible for changes in the ATPase activity.

Cisternal and Lumbar CSF Levels of Arachidonate Metabolites After Subarachnoid Haemorrhage: An Assessment of the Biochemical Hypothesis of Vasospasm*

SummarySeveral naturally occurring compounds have been identified in human cerebrospinal fluid (CSF) after subarachnoid haemorrhage (SAH) as possible vasoactive agents involved in the biochemical mechanism of vasospasm. The authors have measured, in 30 patients admitted for SAH, CSF concentrations of two arachidonic acid metabolites, Prostacyclin and Prostaglandin D2, as representative of vasodilator and vasoconstrictor compounds. CSF samples were made available by lumbar punctures and intraoperative cisternal punctures. Nine patients presented with symptomatic vasospasm: lumbar CSF Prostaglandin D2 levels are significantly higher than in patients without vasospasm. The Cisternal Prostaglandin D2 level is significantly higher than the lumbar CSF concentration; CSF Prostacyclin levels do not significantly differ in the two groups of patients. These data suggest the presence of an imbalanced biochemical situation responsible for promoting vasospasm. The evaluation of cisternal levels of arachidonate metabolites support the hypothesis of the clotting phenomenon around the ruptured aneurysm wall as an important predictive pattern of vasospasm onset after SAH, as shown in computed tomography.

Prostacyclin and vasospasm in subarachnoid hemorrhage from ruptured intracranial aneurysm. A preliminary clinical study.

ABSTRACT – Experimental and clinical observations suggest the importance of arachidonate metabolites in the genesis of symptomatic cerebral vasospasm after subarachnoid hemorrhage. Prostacyclin (PG12) has a well demonstrated vasodilator action. The authors monitored CSF prostacyclin concentration in 12 consecutive cases of subarachnoid hemorrhage with the purpose of correlating the prostacyclin concentration trend with the clinical course and the risk for vasospasm. In three cases patients presented with clinical and radiological signs of vasospasm. CSF prostacyclin concentration showed a typical decreasing trend, which amounted to a minor form of protection from vasospastic agents.

Effect of Nimodipine on Mitochondrial Respiration in Different Rat Brain Areas After Subarachnoid Haemorrhage

The mitochondrial respiration was evaluated in three different rat brain areas (cerebral cortex, hippocampus and brain stem) after experimental subarachnoid haemorrhage (SAH). The haemorrhage was induced by injecting 0.35 ml of autologous arterial blood into cisterna magna. Intravenous administration of Nimodipine (2 micrograms/kg/min for 30 minutes) was started immediately after the haemorrhage induction. At the set time (1 hour after SAH procedure), animals were sacrificed and non-synaptic mitochondria from the above mentioned areas were isolated. The following respiratory parameters were evaluated utilizing glutamate plus malate and succinate plus rotenone as substrates: state 3, state 4, uncoupled state, respiratory control ratio (RCR) and ADP/O ratio. SAH significantly influences respiratory parameters, mainly RCR; the cerebral cortex and brain stem seem to be more sensitive during the acute phase of vasospasm which follows SAH procedure. Nimodipine treatment significantly ameliorates mitochondrial respiratory conditions.

Combined STA/MCA arterial bypass and gradual internal carotid artery occlusion for treatment of intracavernous and giant carotid artery aneurysms

SummaryIntracavernous aneurysms are a clinical diagnostic and technical problem,. The risk of a direct surgical clipping, whenever possible, is high. Carotid ligation remains the classical surgical treatment for inaccessible aneurysms. Internal carotid artery (ICA) ligation is more effective than common carotid artery (CCA) ligation but carries a higher risk of cerebral ischaemia. The performance of ipsilateral extra-intracranial arterial bypass (EIAB) helps to maintain blood flow in the cerebral hemisphere. It also may decrease the collateral flow formation through the circle of Willis with turbulence in the aneurysmal sac, thus enhancing thrombosis.A series of five cases is reported. The results are satisfactory except in one patient who died in the immediate postoperative period for malignant hemispheric edema, in spite of the patent bypass.The EIAB can reduce but not eliminate the risk of ischaemic complications related to ICA ligation.

Nitrosourea derivatives-induced pulmonary toxicity in patients treated for malignant brain tumors. Early subclinical detection and its prevention

Nitrosourea derivatives, such as BCNU and CCNU, are considered useful chemotherapeutic agents in malignant brain tumors combined therapy. Pulmonary toxicity is one of the major side effects demonstrated both in experimental animal models and in human autoptic findings. Pulmonary fibrosis is the end point of progressive functional disorder of respiratory mechanism and alveolo-capillary gas exchanges. Authors present the results of a randomized, double-blind trial of 40 patients previously treated with surgery and radiotherapy and who subsequently underwent BCNU therapy for primary intracranial glioma. Patients underwent functional respiratory examinations at each chemotherapy course interval. Twenty patients received ambroxol (120 mg/day) for 40 days after chemotherapy course. Control patients received placebo with the same schedule and showed a significant reduction of pulmonary functional parameters (DLCO, MMEF, MEF 25%), whereas in the treated group there is no significant variation of these functional parameters. The mechanism of ambroxol is commonly related to the surfactant synthesis enhancement and to the action on bronchiolar pathways.

Low-Cost Fluorescein Detection System for High-Grade Glioma Surgery

BACKGROUND Intraoperative fluorescein detection has been used in the fields of vascular and oncologic neurosurgery since 1948. Modifications of the optics in order to enhance the fluorescence contrast under microscopic view have been developed by many authors. The industries, during the past 10 years, provided commercial high-cost optimized apparatuses. Reviewing the literature, we found that the prototypical techniques were definitely inexpensive but lacked reliability, reproducibility, and standard legal norms. METHODS We describe the developing of a fluorescein detection system that could be economic, simple, effective, and law abiding. RESULTS We employed a commercial violet-blue filter designed for fluorescein excitation in endoscopic procedures and used commercial photographic yellow optical filters for fluorescence detection. All the instrumentation is cleared for clinical use, and its cost is up to 200 times lower than commercial apparatuses. CONCLUSION Our results show a good distinction of fluorescein-stained structures, with overall acceptable operating light conditions.