Shigeharu Takagi

Water extraction fraction and permeability-surface product after intravenous injection in rats.

A quantitative method has been developed to measure the water extraction fraction of rat brain after successive intravenous bolus injections of [15O]water and [11C]butanol based on a mathematical equation developed by the authors. This new method is noninvasive to the brain or craniocervical large vessels and does not require sacrifice of the rats. Arterial concentration curves and total head counts were measured in 8 rats by means of external coincidence detectors. Water extraction fraction in rat brain was 0.67 +/- 0.13 (mean +/- SD) and permeability-surface product was 1.75 ml/g min, where cerebral blood flow and arterial carbon dioxide tension were 1.71 +/- 0.86 ml/g min and 44.8 +/- 14.0 mm Hg, respectively. Water extraction fraction was stable with different measurement times from 20 to 80 seconds.

Measurement of Cerebral Blood Flow in the Rat with Intravenous Injection of [11C]Butanol by External Coincidence Counting: A Repeatable and Noninvasive Method in the Brain

No method has been reported for measuring CBF, repeatedly and noninvasively, in the rat brain. A new method is described, which is noninvasive to the brain, skull, or cervical large vessels. Two pairs of coincidence detectors were positioned, one over the rat brain and the other at the loop of a catheter inserted into the femoral artery. The coincidence head curve and arterial curve were recorded after intravenous injection of 1-[11C]butanol in 15 rats. CBF was calculated by one-compartment curve fitting (CBFo) from 1-min data and with the recirculation corrected height/area method from 3-min data (CBFh · 3min) and 5-min data (CBFh · 5min). CBFo agreed well with CBFh · 5min, although a slight overestimation was observed in CBFh · 3min. The normal CBFo in the normocapnic group (n = 6, paco2 36.7 ± 2.3 mm Hg) was 1.76 ± 0.49 ml/g min (mean ± SD). A good correlation was observed between CBFo (y) and Paco2 (x), and the regression line was y = 0.0629x – 0.715 (r = 0.88, p < 0.0001). We concluded that this method gives the stable blood flow values noninvasively and with a minimum loss of blood (<0.28 ml per measurement). Applications of this method include activation studies, studies on the effect of drugs and treatments, and water and oxygen extraction fraction studies using different tracers in the same rat.

Investigation of Antiphosphatidyl-Serine Antibody and Antiphosphatidyl-Inositol Antibody in Ischemic Stroke Patients

Antiphospholipid syndrome is characterized by arterial or venous thrombosis and the presence of antiphospholipid antibodies (aPL). We measured β2-GPI aCL, IgGaCL, LA, antiphosphatidyl-serine antibody (PS), and antiphosphatidyl-inositol antibody (PI) in each patient at one month after the onset of stroke. In addition, carotid artery echography was performed in patients positive for PI or PS. Among the 250 patients, 13.6% (34/250) were positive for either PI or PS, and 6.8% (17/250) were positive for both. Carotid artery echography performed on these 34 patients showed that the frequencies of increased intimal-medial thickness (IMT) of 1.1 mm or more, plaque, and carotid artery stenosis of 50% or more were all significantly higher in patients positive for antinuclear antibody than those negative for the antibody (P < .05). PI and PS are associated with antinuclear antibody and precipitation of atherosclerosis. Ischemic stroke patients with SLE frequently showed a variety of antiphospholipid-protein antibodies.

A case of hypertrophic pachymeningitis with prolonged headache, attributable to Epstein-Barr virus.

Hypertrophic pachymeningitis is a condition characterized by significant chronic inflammatory thickening of the cranial dura mater, frequently presenting with symptoms such as headache and cranial neuropathy. In this report, we describe a very rare case of hypertrophic pachymeningitis, considered to be attributable to Epstein–Barr virus (EBV), which was diagnosed in a patient who visited our hospital with a complaint of ongoing severe headaches. The diagnosis was based on positive specific serum EBV antibody titers, with VCA‐IgM levels of less than 1:10, VCA‐IgG levels of 1:160, and EBNA levels of 1:40, as well as on the results of magnetic resonance imaging of the head with contrast media.

A Quantitative Model for the Measurement of Cerebral Vascular Extraction Fraction In vivo following Intravenous Injection: Simulation Studies

A mathematical method has been developed by which the cerebral vascular extraction fraction of flow- and diffusion-limited tracers injected intravenously can be measured quantitatively. Successive injections of three tracers are required: a test tracer such as 15O-labeled water; a completely diffusible tracer as a reference tracer and also as a flow tracer; and a tracer for cerebral blood volume (CBV). The arterial tracer concentration curves and total integrated head counts of the test and reference tracers, as well as CBF and CBV values, are required to calculate the extraction fraction. No calibration is required between the head counts and arterial curves. No decay correction of the head and arterial activity is required, because isotopic decay is explicitly included in the equation. The effect of nonextracted test tracer can be corrected. Simulation studies have shown that the calculated extraction fraction values are not sensitive to measurement error in CBF, CBV, partition coefficient, change in measurement time, or time shift effect between the arterial and head data. If there is mixing of two different tissues in the brain, the calculated extraction fraction values are close to the weighted mean values of extraction fraction by relative weight of the tissues. It is concluded that it is possible to apply this method to human studies with a positron emission tomograph scanner and to animal studies with external coincidence detectors.

A Patient with Hashimoto's Encephalopathy Presenting with Convulsive Seizure Alone as the Initial Symptom

A 71-year-old Japanese woman with Sjögren syndrome, Hashimotos disease and a 6-month history of cognitive impairment was admitted to our hospital because of consciousness disturbance and convulsion. Her convulsive seizure disappeared by intravenous administration of diazepam following carbamazepine, and conscious level became alert the next day. But, her cognitive function was persistently deteriorated, and a score of mini-mental state examination (MMSE) was 17/30 points. Magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) of the brain did not show any abnormal findings. The electroencephalogram showed increased slow waves in bilateral parieto-occipital regions. Serum anti-thyroglobulin antibodies were elevated (1780 U/ml), but thyroid function was within the normal range. In addition, anti-NAE (NH2-terminal of α-enolase) antibodies were positive. We diagnosed Hashimotos encephalopathy, and started steroid therapy. Her cognitive function gradually improved after steroid therapy, and convulsive seizure did not recur until 3 months later. We emphasize that Hashimotos encephalopathy should be considered even in patients with convulsive seizure of adult onset without thyroid dysfunction.

Estimation of the perioperative management of stroke patients receiving antiplatelet therapy

外科的手術あるいは内視鏡検査前などにおける抗血小板薬休薬の至適期間を,血小板凝集の面から検討した.手術・検査のために抗血小板薬を一時中止した患者22例(アスピリン9例,チクロピジン13例)を対象とし,休薬前,休薬3日,7日,14日目に比濁法にて血小板最大凝集率を求めた.その結果,アスピリン群では休薬前に対し休薬3日後より有意に凝集能が亢進し(14.0±8.5% vs 48.1±31.2%; p<0.05),チクロピジン群では休薬14日後に初めて有意差(19.5±11.4%vs58.4±30.8%; P<0.05)を認めた.確実な目処もなく日常的に行われている休薬期間を最小限にするという観点から血小板凝集能を指標とした場合,アスピリンは術前3日,チクロピジンは2週間が望ましいと結論された.