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F Iannotti

Publications and source records attributed to F Iannotti.

At least 55 records · Page 3Linked to original sources
PubMed1991

Blood-brain barrier permeability to micromolecules and edema formation in the early phase of incomplete continuous ischemia.

The distribution patterns of ionic Lanthanum (La3+; mol. wt. 139) were evaluated after 15, 30 and 60 min of middle cerebral artery occlusion in perfused-fixed rats. Blood-brain barrier (BBB) permeability to Evans blue (EB) and horseradish peroxidase (HRP; mol. wt. 40,000) in vivo was also evaluated. Brain tissue specific gravity was measured. An increase in brain water content was found as early as 30 min following occlusion. HRP and EB extravasation was not observed. La3+ crossed the interendothelial clefts of venules and capillaries at 30 and 60 min and was seen in both extracellular and intracellular brain compartments at 60 min. La3+ extravasation was seen in nonedematous areas bordering the regions of water accumulation. Our findings suggest that the early phase of incomplete continuous ischemia is accompanied by changes in BBB permeability and the interendothelial clefts of venules and capillaries seem to represent one of the early sites of ischemic damage.

Animals↗
PubMed1991

Chronic pain: a PET study of the central effects of percutaneous high cervical cordotomy.

We have studied 5 patients with unilateral, severe chronic pain due to cancer before and after percutaneous, ventrolateral cervical cordotomy to investigate the central effects of the procedure. The aim was to identify the functional anatomical correlates of abolishing unilateral nociceptive input to the brain. Patients were investigated by positron emission tomography using C15O2 to evaluate cerebral blood flow. Comparisons were made between the patients with unilateral pain before cordotomy and normal volunteers. These demonstrated significantly less blood flow in 3 out of 4 of the individual quadrants of the hemithalamus contralateral to the side of pain (P less than 0.01-0.05). These differences were abolished by cordotomy. Comparison of the patients before and after cordotomy showed a significant decrease in blood flow in the dorsal anterior quadrant of the thalamus contralateral to the side of pain (P less than 0.05) which was normalised after cordotomy. There were no significant changes in the prefrontal or primary somatosensory cortex. We conclude that chronic pain results in a decrease of synaptic activity at thalamic level either from decreased activity in neurones projecting to that region and/or attenuated local neuronal firing. We have demonstrated no secondary remote effects in cortex, indicating the importance of subcortical mechanisms in central responses to chronic pain.

Aged↗
PubMed1991

99TCm-HMPAO SPECT studies in traumatic intracerebral haematoma.

Traumatic intracerebral haematomas are a common neurosurgical emergency. Their management, particularly the role of surgical removal, is controversial. Deterioration often occurs late, and is unpredictable. Eight patients with traumatic intracerebral haematomas were admitted to the neurosurgical unit to monitor their clinical state. All were studied within 48 hours of admission with single photon emission computerised tomography (SPECT), using the recently introduced radionuclide 99Technetiumm-Hexamethyl propylene amine oxime (99Tcm-HMPAO). At the time of the SPECT study, all the patients had been clinically stable. Three patients remained so; in the other five, the conscious level deteriorated, necessitating craniotomy and evacuation of the haematoma. In all the patients, the SPECT studies demonstrated perfusion defects that corresponded to the location of the haematoma, as demonstrated by computerised tomography (CT). However, in the five patients who subsequently deteriorated, the perfusion defects seen on the SPECT scan appeared larger than the haematoma, as seen on the CT scan. In addition, there was widespread poor retention of 99Tcm-HMPAO in the ipsilateral hemisphere. These differences were quantifiable. Interestingly, these differences were present at a time when the patients were clinically stable, before their deterioration. It is concluded that SPECT studies with 99Tcm-HMPAO are of possible use as predictors of late deterioration in the management of traumatic intracerebral haematomas.

Adolescent↗
PubMed1989

99Tcm-HMPAO SPET and cerebral blood flow: a study of CO2 reactivity.

Single photon emission tomography (SPET) studies using 99Tcm-HMPAO are in widespread use in the functional imaging of cerebral blood flow (CBF). While qualitatively the images correlate well with other imaging modalities, there are doubts as to the quantitative accuracy of this method. In particular, the uptake and subsequent retention of 99Tcm-HMPAO in conditions of high flow is known to be nonlinear. In this study, we compared the quantitative retention of 99Tcm-HMPAO in eight subjects under conditions of normo- and hypercapnia. There was no significant increase, despite a mean rise of the end tidal pCO2 from 5.06 to 7.06 kPa, a stimulus that is known to provoke an 80-100% rise in CBF. We conclude that SPET studies with 99Tcm-HMPAO provide excellent qualitative images of the distribution of CBF, but that quantitative data in ml hg-1 min-1 must be interpreted with caution.

Adult↗
PubMed1989

Brain edema: a classification based on blood-brain barrier integrity.

Brain edema is a frequent complication of a variety of brain injuries and disorders. Two primary types of brain edema can be distinguished depending upon the integrity of the blood-brain barrier. With intact-barrier edema, the permeability of the blood-brain barrier is normal and brain edema results from a disturbance in ionic homeostasis. This type of edema is typically associated with swelling of the brain cells and a contraction of the extracellular space. In open-barrier edema, the permeability of the blood-brain barrier is increased and brain edema results from the oncotic forces generated by an influx of serum proteins into brain. In this case, the edema fluid accumulates primarily in the extracellular space. To a greater or lesser extent, both types of edema occur simultaneously in the majority of clinical conditions; however, one form usually predominates and demands the attention of both the scientist and clinician. Furthermore, classification of brain edema based upon blood-brain barrier integrity is useful to focus research on common mechanisms for brain edema formation and to direct therapy. This review considers intact-barrier and open-barrier edema with regard to their (a) histological features, (b) biophysical forces, (c) possible biochemical mediators, (d) mechanisms of resolution, and (e) implications for therapy.

Blood-Brain Barrier↗
PubMed1988

Quantitative assessment of blood-brain barrier permeability in multiple sclerosis using 68-Ga-EDTA and positron emission tomography.

Fifteen patients with definite multiple sclerosis were examined with high volume delayed (HVD) CT scan and positron emission tomography (PET) using 68-Ga-EDTA as a tracer. The passage of 68-Ga-EDTA across the blood-brain barrier (BBB) was measured by using multiple graphical analysis. This method permits the simultaneous calculation of a blood to brain influx constant Ki (ml/g-1 min-1) and of the plasma volume Vp (ml/g-1). Focal areas of abnormal CT enhancement and pathological accumulation of 68-Ga-EDTA were visualised in four patients who were all examined during a clinical exacerbation of the disease. The mean Ki value measured in these areas was 12.5, SD 3.4 indicating a moderate but significant increase of BBB permeability compared with the value found in normal tissue (3.2, SD 0.9). No parallel increase in Vp values was found in these pathological areas. Quantitative data obtained with PET seems to provide further insight into the study of BBB function in multiple sclerosis.

Adolescent↗
PubMed1985

Brain tissue pressure in focal cerebral ischemia.

Twenty-three anesthetized cats underwent permanent middle cerebral artery occlusion in a study of the relationships of regional cerebral blood flow, ventricular fluid pressure, brain tissue pressure, and ischemic edema formation. A pressure gradient of 8 mm Hg developed between ischemic tissue and normally perfused tissue during a 4-hour observation period after occlusion. Brain water accumulated as tissue pressure rose, while blood flow in the same area fell. The data suggest, but do not prove, that ischemic brain edema causes tissue pressure to rise focally, and that blood flow to the ischemic zone is compromised further by the resultant hydrostatic pressure gradient.

Animals↗
PubMed1984

Brain tissue pressure: physiological observations in anesthetized cats.

This study of direct tissue pressure measurement from brain parenchyma in 25 anesthetized cats focuses on steady-state observations and responses to some common physiological manipulations. Tissue pressure recording by a needle system can be done accurately without significant alterations of the blood-brain barrier, brain water content, regional cerebral blood flow, and cerebrovascular reactivity to changes in PaCO2 and cerebral perfusion pressure. Methodological details, including in vitro and in vivo validation, are described.

Anesthesia, General↗
PubMed1983

Simultaneous determination of regional cerebral blood flow and blood--brain glucose transport kinetics in the gerbil.

Cerebral blood flow (CBF) and unidirectional transport of glucose from blood to brain were measured simultaneously in four brain regions of the pentobarbital-anesthetized gerbil. The method consisted of the intravenous injection of a bolus containing [14C]butanol and [3H]glucose, followed by continuous withdrawal of arterial blood and sampling of brain 25 s later. CBF was lowest in the cerebral cortex (50 ml 100 g-1 min-1), highest in the brainstem (89 ml 100 g-1 min-1), and intermediate in the basal ganglia and cerebellum (66 and 69 ml 100 g-1 min-1, respectively). The kinetics of blood-to-brain glucose transport were measured in animals whose blood glucose concentration had been altered by glucose or insulin injections. The half-saturation constant for glucose transport (Km) was similar in all brain regions (7.37-8.14 mM), while the maximal rate of transport (Vmax) was lowest in the cerebral cortex (1.55 mumol g-1 min-1) and significantly higher in the basal ganglia, cerebellum, and brainstem (1.81-2.02 mumol g-1 min-1). These values for CBF and glucose transport are similar to those reported in the literature for other pentobarbital-anesthetized animals. The method provides a simple and rapid technique for determining the effect of ischemia and alterations in CBF on blood-to-brain glucose transport.

Animals↗
PubMed1983

Ischemia reduces blood-to-brain glucose transport in the gerbil.

The effect of carotid occlusion on cerebral blood flow (CBF), brain plasma volume for sucrose (Vplsuc), and unidirectional transport of glucose from blood to brain was measured in four regions of gerbil brain. Unilateral common carotid artery occlusion caused a variable decrease in CBF to the ipsilateral cerebral cortex and basal ganglia, with no change in CBF to the contralateral structures; cerebellum, or brainstem. One hour of bilateral carotid artery occlusion reduced flow to near zero in the cerebral cortex and to 30% of control in the basal ganglia, while increasing CBF to the cerebellum and brainstem. There was a significant decrease in the Vplsuc of the cerebral cortex and basal ganglia after 1 h of ischemia, perhaps due to compression of the intravascular space by edema fluid. Blood-to-brain glucose transport, 1 min after release from 1 h of bilateral carotid occlusion, was decreased in the cerebral cortex and basal ganglia, but not in the cerebellum or brainstem. These data indicate that 1 h of complete or incomplete ischemia reduces the rate of unidirectional glucose transport from blood to brain.

Animals↗
PubMed1982

Cerebrovascular effects of prostaglandin inhibitors in the gerbil.

Autoregulation of cerebral blood flow (CBF) to mean arterial blood pressure (MABP) of 40-50 mm Hg has been demonstrated in the spontaneously breathing gerbil anaesthetised with barbiturate (60 mg/kg). CO2 reactivity has also been assessed at 2.8% change CBF/mm Hg change in arterial PCO2. In six animals pretreated with indomethacin (3 mg/kg), autoregulation was preserved although the resting CBF was significantly reduced, but CO2 reactivity was completely abolished. 1-n-Butyl imidazole, a specific thromboxane synthetase inhibitor, was used in six other animals (3 mg/kg), and this abolished CO2 reactivity while preserving autoregulation; the effect of this agent has not been described previously. Both drugs inhibit different pathways of prostaglandin metabolism and may interfere with normal CO2 reactivity in several ways. Two explanations are that prostaglandins constitute the final common pathway in effecting cerebrovascular response to CO2 or, alternatively, that the free radicals and ionic fluxes generated during prostaglandin metabolism are a coincidental source of the hydrogen ion changes required.

Animals↗
PubMed1981

Spinal haemangioblastoma associated with syringomyelia and multiple lung lesions.

Haemangioblastomas involving the spinal cord are uncommon but by no means unknown. It is well established that haemangioblastomas of the central nervous system are commonly associated with lesions in the retinae and in various abdominal organs. The simultaneous occurrence of similar tumours in the lung is less common and not well recognized. The case of a man with a haemangioblastoma of the spinal cord with many small haemangioblastomas of the lung is reported here.

Hemangiosarcoma↗
PubMed1980

Supratentorial hemangioblastoma in a child. Case report.

Hemangioblastomas are rarely seen in the supratentorial region, especially in childhood. The case of a 10-year-old boy with left parieto-occipital cystic hemangioblastoma is reported. The neoplasm was not attached to the dura, nor was it associated with von Hippel-Lindau syndrome or with erythrocythemia. Cerebral angiography showed no evidence of a vascularized tumor, whereas computerized tomography gave more accurate information. The gross and microscopic appearance of the lesion is described, and a review of similar cases previously reported in the literature is presented.

Brain Neoplasms↗
PubMedDate not supplied

Simplified, noninvasive PET measurement of blood-brain barrier permeability.

Blood-brain barrier (BBB) permeability to [68Ga]EDTA was measured by positron emission tomography (PET) in four normal volunteers and in 11 patients with brain tumors. A unidirectional transfer constant, Ki, was calculated applying multiple-time graphical analysis (MTGA). This method allows the detection of backflux from brain to blood and, by generalization, the measurement of the constant Kb (brain to blood). Furthermore, the need for an independent measurement of the intravascular tracer is obviated: MTGA itself provides an estimate of the cerebral plasma volume (Vp). In the four normal volunteers the Ki was 3.0 +/- 0.8 X 10(-4) ml g-1 min-1 (mean +/- SD) and the Vp 0.034 +/- 0.007 ml g-1. A net increase in Ki up to a maximum of 121.0 X 10(-4) ml g-1 min-1 (correspondent value of Kb = 0.025 min-1) as well as an increase of Vp was observed in malignant tumors. The input function was calculated using both the [68Ga]EDTA concentration in sequential arterial blood samples and, noninvasively, the activity derived from the superior sagittal sinus image. The values of Ki and Vp from these two calculations were in good agreement. The application of MTGA to PET permits the evaluation of passage of substances across the BBB without making assumptions about the compartments in which the tracer distributes.

Adult↗
PubMedDate not supplied

Cerebral blood flow and edema following carotid occlusion in the gerbil.

A technique for measuring focal cerebral blood flow (CBF) and brain specific gravity (SG) in gerbils is described; CO2 reactivity and autoregulation were tested. The mean CBF was 29.5 +/- 4.5 ml/100 gm/min and brain SG 1.0500 +/- 0.0004. Unilateral carotid occlusion resulted in a reduction of flow to 12.8 +/- 5.8 ml/100 gm/min in the ipsilateral hemisphere with little change in the contraleteral hemisphere; there was also a decrease in brain SG. One hour after occlusion, brain edema, as judged by decreased SG, developed at CBF less than 20 ml/100 gm/min and reached maximal levels at 7 +/- 2 ml/100 gm/min. The amount of edema appeared to be related chiefly to the residual post-occlusion flow. With bilateral occlusion, CBF was close to zero and there was no change in SG, indicating that in the "no flow" situation, there is no edema.

Animals↗