Regional cerebrovascular transport of leucine as measured by the in situ brain perfusion technique.

Leucine influx into six brain regions was determined in anesthetized rats with the in situ brain perfusion technique using either saline or plasma perfusate. This technique has several advantages over other methods such as the brain uptake index (BUI) technique. The concentration dependence of L-leucine influx was best described by a model with a saturable and a nonsaturable component. For the saturable component, Vmax equaled 10.67 +/- 0.21 X 10(-4) mumol s-1 g-1 and Km equaled 0.0257 +/- 0.0009 mumol ml-1, whereas the constant of nonsaturable diffusion (Kd) equaled 0.957 +/- 0.067 X 10(-4) s-1 in the parietal lobe during saline perfusion. Vmax was higher in the cortical lobes than in other brain areas, probably owing to a greater capillary surface area. There were no regional differences in Km or Kd. The apparent Km for L-leucine during plasma perfusion was 20 times greater than the Km during saline perfusion, and 3 to 4 times greater than the plasma leucine concentration, owing to competitive inhibition of leucine transport by other large neutral amino acids in plasma. These results for Vmax, Km, and Kd differ by three- to fourfold from previous estimates obtained with the BUI technique. The high apparent Km during plasma perfusion indicates that leucine influx is a linear function of plasma concentration up to 0.5 mumol ml-1 when the plasma concentrations of other amino acids remain constant, whereas influx would be approximately constant when plasma concentrations of all large neutral amino acids increased or decreased by a constant fraction.

Cerebral blood flow measurement of severely head-injured patients during mild hypothermia.

In 14 patients with severe head injury, the cerebral blood flow (CBF) during mild hypothermia therapy was measured. Their Glasgow Coma Scale scores on admission were 8 or less and the intracranial pressures were greater than 20 mmHg despite conventional therapy. The CBF was measured with two-level stable xenon CT techniques. And in 11 patients, the cerebral metabolic rates for oxygen (CMRO2) was also calculated. All cases were divided into two groups according to the outcome at discharge by using the Glasgow Outcome Scale, good outcome group in 6 and poor outcome one in 8. The values of mean CBF and CMRO2 of each group were 25.6 +/- 6.6 vs 24.4 +/- 6.4 ml/100 g/min and 1.26 +/- 0.45 vs 0.79 +/- 0.31 ml/100 g/ml, respectively. There were no statistically significant differences between both groups. Single CBF measurement during this therapy may not be helpful as a factor of prognosis evaluation in patients with severe head injury.

Kinetics of amino acid transport at the blood-brain barrier studied using an in situ brain perfusion technique.

The in situ brain perfusion technique of Takasato et al. allows accurate measurements of regional amino-acid influx across the blood-brain barrier. Influx can be determined in the absence of competing amino acids, using saline perfusate, or in the presence of physiological concentrations of amino acids, using plasma or blood perfusate. The concentration dependence of cerebrovascular LNAA transport is best described by a model with a Michaelis-Menten saturable and a nonsaturable component. Vmax values for four LNAAs are similar and average 10 X 10(-4) mumol X sec-1 X g-1. In contrast, Km values differ by up to 10-fold with the lowest value for leucine. Competitive inhibition increases the apparent Km for transport from plasma by approximately 20-fold. These data provide accurate new estimates of the kinetic constants that describe amino-acid transport across the blood-brain barrier. In addition, they indicate that the cerebrovascular transport capacity (Vmax) and affinity (1/Km) are greater than previously reported with the brain uptake index technique.

Kinetic analysis of L-leucine transport across the blood-brain barrier.

Unidirectional L-leucine influx across cerebral capillaries was measured at different concentrations with an in situ rat brain perfusion technique, which has several advantages over presently-used methods such as the Brain Uptake Index (BUI) technique. The maximal influx rate (Vmax) and half-saturation concentration (Km) equaled 1.07 +/- 0.02 X 10(-3) mumol X s-1 X g-1 and 0.026 +/- 0.002 mumol X ml-1, respectively, for the saturable component, and the constant for non-saturable influx equaled 6.8 +/- 1.4 X 10(-5) s-1. These values differ by 3-4-fold from respective values obtained with the BUI technique.

Brain uptake of a food dye, erythrosin B, prevented by plasma protein binding.

Although food colors have been held responsible for several behavioral disorders and do affect neuronal function when directly applied, there is no information on whether significant quantities of the dyes appear in the brain after consumption or parenteral administration. [14C]erythrosin B was administered directly into the circulation of mature rats and radioactivity was measured thereafter in brain regions at several times. Although insignificant parenchymal radioactivity was detected in brains perfused with dye in whole blood, significant concentrations of [14C]erythrosin B were detected in all brain regions when perfused with protein-free Ringers, as predicted from the octanol-water partition coefficient of the dye. Thus, significant brain uptake of intravascular dye is normally prevented by its binding to plasma protein (greater than 99% bound) and by the blood-brain barrier impermeability to the dye-protein complex. Sensitivity to food dyes such as erythrosin B in some individuals may reflect altered plasma protein binding capacity, which can vary with age and disease.

Ossifying fibroma involving the paranasal sinuses, orbit, and anterior cranial fossa: case report.

We report a case of ossifying fibroma involving the paranasal sinuses, orbit, and anterior cranial fossa. Ossifying fibroma is a benign fibro-osseous tumor, rarely involving the anterior cranial base. The patient was admitted because of exophthalmos and diplopia. The lesion was totally removed surgically. Grossly, it had a thin osseous capsule. The microscopic examination showed mainly fibrous tissues and lamellar bone trabeculae rimmed by osteoblasts and myxomatous areas in some parts. The histopathological aspect of this entity is discussed with reference to the differential diagnosis from monostotic fibrous dysplasia.

Gross total removal of adult brainstem glioma--two case reports.

Two adult patients with brainstem glioma were successfully treated surgically. A 37-year-old male had a dorsally exophytic pontine glioma developing from the fourth ventricular fundus, and another 27-year-old male an intrinsic nodular mesencephalic glioma. Preoperative magnetic resonance imaging clearly visualized the tumor margin in both cases, and showed the relationship between the tumor and brainstem structure accurately. The tumors were radically excised using intraoperative evoked potential monitoring, ultrasonic surgical aspirator, and microsurgical techniques. Surgery is indicated when the tumor margin in the brainstem and adjacent region is clear, and the approach is possible without affecting the functional prognosis.

Effects of encephalo-duro-arterio-synangiosis on childhood moyamoya patients--swift disappearance of ischemic attacks and maintenance of mental capacity.

The effect of encephalo-duro-arterio-synangiosis (EDAS) upon chronic cerebrovascular ischemia in 65 pediatric moyamoya patients was evaluated by the postoperative interval before complete disappearance of ischemic attacks and changes in pre- and postoperative intelligence (IQ) or development quotients (DQ). The ischemic attacks disappeared after a mean period of 239 days, in three-fourths of patients within a year and in about one-fourth within the second year. This was very fast compared with the natural course of the disease. There was no significant difference in DQ/IQ before and after the operation. The mentally normal (IQ/DQ greater than or equal to 86) population in the postoperative patients was greater than in the natural course of the disease, although fewer in the preoperative group. This shows that EDAS delayed or prevented the deterioration in mental capacity usually present but often overlooked in the natural course of pediatric moyamoya disease.

[A case of dural arteriovenous malformation in the anterior cranial fossa presenting with intracranial hemorrhage].

We report a case of dural arteriovenous malformation (dAVM) in the anterior cranial fossa presenting with intracranial hemorrhage. The patient was a 60-year-old man who became unconscious shortly after developing an acute headache. Computed tomography performed on admission demonstrated a left frontal intracranial hematoma together with subarachnoid hemorrhage and a subdural hematoma. Cerebral angiography revealed a dAVM in the left anterior cranial fossa supplied by the anterior ethmoidal arteries bilaterally from enlarged ophthalmic arteries and which drained into the superior sagittal sinus via a dilated cortical vein with aneurysmal dilatation. The lesion was successfully resected via a left frontal craniotomy. Although reports of dAVMs in the anterior fossa are rare, a number of new cases have been described recently. The clinical features and angiographic findings in 58 cases are analyzed. The average age at the time the patients presented was 55.8 years, and males predominated (85.0%). Intracranial hemorrhage was the presenting manifestation in most cases (74.1%). Ocular symptoms occurred especially in cases with a posterior venous drainage pattern. Angiographically, the dAVM was most frequently supplied by the anterior ethmoidal artery (94.8%) and drained into a pial vein with vascular sac in almost every case. Rupture of this varicose dilatation often caused intracranial hemorrhage. The main drainage sinus or vein was usually the superior sagittal sinus (86.0%). The nidus was usually in the dura mater, but recently a nidus in the brain parenchyma has also been reported. The pathogenesis of this entity remains unclear, but some impairment of normal embryonic vascular development is the most likely etiology. Surgical resection remains the treatment of choice.

[A case of steroid psychosis associated with betamethasone].

Psychotic side effects of steroids have been observed at relatively high frequency if mild cases, such as euphoria, are included, while it has been said that incidences differ among kinds of steroids. We reported a case developing severe schizophrenia-like symptoms following the treatment with betamethasone although this drug is believed to be rarely involved in steroid-induced psychosis, and its psychotic side effects have been rarely reported. When betamethasone was administered for progressive peripheral facial paralysis at a mean daily dose of 7mg, psychotic symptoms appeared from the 15th treatment day. Psychosis began with interrupted appearance of excitation, autism, and misanthropia. Although the steroid was gradually decreased in dose because of abatement of facial paralysis, not only psychotic symptoms were aggravated, but also appeared hallucination. Thus the steroid was withdrawn before the scheduled date while its dose was gradually decreased, and haloperidol was administered. Psychotic symptoms were gradually eliminated and completely disappeared about 40 days after onset.

[Pediatric metrizamide CT cisternography and CT ventriculography (author's transl)].

We have studied the diagnostic value of computed tomography with metrizamide CSF enhancement in 37 infants. According to the method of injection, we called CT cisternography, CT ventriculography and CT cystography. These methods were useful for the morphologic and dynamic evaluation of the CSF pathways. We used them especially for the evaluation of hydrocephalus, skull base tumor, infantile subdural hematoma and its allied diseases, or congenital cystic lesion such as Dandy-Walker syndrome. The side effects in children are much less than those in adults.