Improved Measurements of Muonic Helium Ground-State Hyperfine Structure at a Near-Zero Magnetic Field.

Muonic helium atom hyperfine structure (HFS) measurements are a sensitive tool to test the three-body atomic system and bound-state quantum electrodynamics theory, and determine fundamental constants of the negative muon magnetic moment and mass. The world's most intense pulsed negative muon beam at the Muon Science Facility of the Japan Proton Accelerator Research Complex allows improvement of previous measurements and testing further CPT invariance by comparing the magnetic moments and masses of positive and negative muons (second-generation leptons). We report new ground-state HFS measurements of muonic helium-4 atoms at a near-zero magnetic field, performed for the first time using a small admixture of CH_{4} as an electron donor to form neutral muonic helium atoms efficiently. Our analysis gives Δν=4464.980(20) MHz (4.5 ppm), which is more precise than both previous measurements at weak and high fields. The muonium ground-state HFS was also measured under the same conditions to investigate the isotopic effect on the frequency shift due to the gas density dependence in He with CH_{4} admixture and compared with previous studies. Muonium and muonic helium can be regarded as light and heavy hydrogen isotopes with an isotopic mass ratio of 36. No isotopic effect was observed within the current experimental precision.

Demonstration of Muon-Beam Transverse Phase-Space Compression.

We demonstrate efficient transverse compression of a 12.5 MeV/c muon beam stopped in a helium gas target featuring a vertical density gradient and crossed electric and magnetic fields. The muon stop distribution extending vertically over 14 mm was reduced to a 0.25 mm size (rms) within 3.5 µs. The simulation including cross sections for low-energy µ^{+}-He elastic and charge exchange (µ^{+}↔ muonium) collisions describes the measurements well. By combining the transverse compression stage with a previously demonstrated longitudinal compression stage, we can improve the phase space density of a µ^{+} beam by a factor of 10^{10} with 10^{-3} efficiency.

Endovascular Treatment of Urgent Carotid Occlusion. Case selection & Technique.

SUMMARY: Emergency revascularization of acute carotid artery occlusion is still controversial.We treated 15 patients (13 men and two women, mean age of 67.3 years) with acute atherosclerotic carotid occlusion by endovascular procedures and evaluated the usefulness of this treatment. All of the patients were evaluated with emergency MRI and MRA before treatment. Intracranial tandem arterial occlusion due to distal embolism was observed in nine patients, and contralateral carotid stenosis (> 70%) was observed in seven. The mean NIHSS score of the patients was 15.4 +/- 7.4 (mean +/- SD) before treatment. Treatment modality included local intraarterial fibrinolysis (LIF), percutaneous transluminal angioplasty (PTA), and carotid artery stenting (CAS). A protective balloon was successfully placed in the distal carotid artery through the plaque before recanalization in seven patients. Three patients were treated with LIF+PTA, five with PTA+CAS, six with LIF+PTA+CAS, and one with PTA only. Successful recanalization of the carotid artery was obtained in 14 of the 15 patients, and distal tandem middle cerebral artery occlusion was also successfully recanalized in eight of the nine patients. GOS was four or five in eight patients (good outcome group) and 1-3 in seven patients (poor outcome group). Mean NIHSS score of the 15 patients was (6.9 +/- 7.4) after treatment. Preoperative NIHSS score (10.3 +/- 7.4) in the good outcome group was significantly lower than that (21.3 +/- 5.4) in the poor outcome group. The protective balloon technique, PTA with stenting, seems to be useful for acute revascularization of urgent carotid occlusion. Simultaneous treatment of the intracranial tandem occlusive lesion is essential to achieve good clini-cal results. Patients with acute carotid occlusion with NIHSS scores of less than 16 could be good candidates for this advanced treatment.

[Electroencephalography and prognosis in stroke patients].

Electroencephalography (EEG) and its relationship to prognosis were studied in 105 patients with cerebrovascular disease in the acute to subacute stages. Twenty cases had normal EEG, and most of them recovered well. Fifty-five cases had mildly to moderately abnormal EEG with focal asymmetric or slow waves in the unilateral hemisphere. Among them, 41 cases (75%) recovered to the extent of being capable of independent walking, 38 cases (69%) recovered sufficiently to engage in independent activities of daily livings (ADL) and 42 cases (76%) returned home. On the other hand 30 cases who had severely abnormal EEG with diffuse slow waves in the unilateral or bilateral hemispheres showed a poor prognosis. Among them, 18 cases (60%) were confined to bed, 20 cases (69%) remained in totally dependent ADL, and 4 cases (13%) died. Thus, EEG is shown to reflect well functional recovery in stroke patients.

[The profit of the anesthetic work in Tsukuba Medical Center Hospital].

Recently, it has been reported that many hospitals in Japan are facing financial difficulties. In order to study profit and loss of anesthetic work, we calculated costs and fees of 78 anesthetic cases experienced in Tsukuba Medical Center hospital in April, 1993, using our original formula. We compared the profit per hour among 4 groups; the local anesthesia with subcutaneous injection, the general anesthesia alone, the general anesthesia with epidural anesthesia or brachial plexus block, and the epidural and/or spinal anesthesia. Furthermore we compared elective cases with emergency surgery in each group. The profits of the anesthetic work were about -120000 yen for a month. There were two factors which influenced the profits of the hospital, one was whether we selected the general anesthesia or not, and the other was the length of the anesthetic time. The loss in the emergency surgery with the epidural and/or spinal anesthesia was greater than the elective surgery with the same anesthesia. However, in the other anesthesia groups, there were no differences between elective and emergency surgery.

Sinus node recovery function is relatively well preserved under halothane anaesthesia in children.

The purpose of this study was to evaluate the effect of halothane on sinus node recovery time (SNRT). Nine children with congenital heart disease scheduled for cardiac catherization were studied. After the routine procedure, the sinus node was paced at rates of 120, 150 and 180 beats per minute. SNRTs were measured with control conditions and under 1 MAC halothane anaesthesia. The absolute SNRT was standardized and expressed as '%SNRT' and 'Corrected SNRT (CSNRT)'. CSNRT was slightly prolonged by halothane (P = 0.042), while the %SNRT was not significantly prolonged. We conclude that the recovery function of the sinus node is relatively well preserved under 1 MAC halothane in children.

[The effects of preanesthetic oral clonidine upon heart rate response to intravenous atropine in patients during general anesthesia].

In awake subjects the positive chronotropic effect of intravenously administered atropine 10 micrograms.kg-1 has been demonstrated to be blunted by preanesthetic medication of oral clonidine 5 micrograms.kg-1. The aim of the present study is to investigate whether general anesthesia could alter the clonidine-induced attenuation of positive chronotropic effect by atropine. Thirty-two patients were randomly assigned to one of the two groups; patients of the clonidine group received oral clonidine 5 micrograms.kg-1 (n = 12), whereas those of the control group received no clonidine. General anesthesia was induced with intravenous thiamylal 4-5 mg.kg-1, and was maintained with enflurane and nitrous oxide in oxygen after endotracheal intubation. Following the stable circulatory period of 10 min, hemodynamic measurements were made at 1 min intervals for 10 min after atropine 10 micrograms.kg-1 was administered intravenously as a bolus in both groups. A significant attenuation in heart rate response to intravenous atropine 10 micrograms.kg-1 was observed in patients receiving clonidine 5 micrograms.kg-1, as compared with that in the control group (P less than 0.01); maximal increases in heart rate were 15 +/- 8 and 22 +/- 6 beats.min-1 (mean +/- SD) in the clonidine and control groups, respectively. It is concluded that clonidine 5 micrograms.kg-1 blunts the heart rate response to intravenous atropine 10 micrograms.kg-1 in patients anesthetized with enflurane and nitrous oxide in oxygen.

Relation of supersensitivity to cerebral vasospasm induced by oxyhaemoglobin.

There have been reports that superior cervical ganglionectomy (SCG) is effective as a treatment for cerebral vasospasm following subarachnoid haemorrhage (SAH). On the other hand, denervation supersensitivity is supposed to play an important role in vasospasm. The two accounts contradict each other. To investigate this problem, various examinations were performed using the exposed basilar arteries of cats. We have accepted that oxyhaemoglobin (Oxy-Hb) is an important spasmogenic substance. Therefore, the change in vascular reactivity to Oxy-Hb was investigated after various kinds of denervations. It was confirmed that Oxy-Hb has no adrenergic receptor agonist properties because the Oxy-Hb inducing vasospasm was not suppressed by Prazosin or phenoxybenzamine. As a result of this, it is not likely that augmentation of Oxy-Hb inducing vasospasm is caused by deviation supersensitivity. Thus, the non-deviation supersensitivity became a topic of investigation. The basilar arteries were denervated by chemical treatment (reserpine, 6-hydroxydopamine) or bilateral SCG to examine the change in the reactivity to noradrenaline or Oxy-Hb. An increase in reactivity to noradrenaline was observed with the denervations. In contrast, no change in reactivity to Oxy-Hb was found. In conclusion, it was observed that deviation and non-deviation supersensitivity do not participate in vasospasm, in so far as vasospasm is caused by Oxy-Hb.

[Experimental cerebral vasospasm induced by oxyhemoglobin and the sympathetic nervous system (Part 2): An investigation into denervation supersensitivity].

UNLABELLED: The pathological mechanism of cerebral vasospasm following subarachnoid hemorrhage has not been well clarified until now. There have been reports that denervation supersensitivity in cerebral vessels occurring after subarachnoid hemorrhage may possible play a role in the appearance of cerebral vasospasm. On the other hand, we have accepted that oxyhemoglobin (Oxy-Hb) is an important spasmogenic substance. In the present study, we investigated the effect of chemical denervation (reserpine or 6-hydroxydopamine: 6-OHDA) and surgical denervation (bilateral superior cervical ganglionectomy: SCG) on the constrictive sensitivity of cat basilar arteries to noradrenaline (Nor) and oxyhemoglobin (Oxy-Hb) in situ. METHOD: Adult cats were anesthetized with intramuscular pentobarbital and maintained on a respirator through a tracheostomy. By the transclival approach, the basilar artery was exposed. A cannula was then inserted into the subarachnoid space, and through it, Oxy-Hb and Nor were injected. The sequential changes in caliber of the basilar artery were measured using photography. SCG was done 7 days before the application of Nor or Oxy-Hb and 14 days before application of Oxy-Hb. Pretreatment with reserpine was done as follows: 1 mg/kg of reserpine was injected subcutaneously once each day for 2 days. On the following day, the sensitivity of the basilar arteries to Nor or Oxy-Hb was assessed. Pretreatment with 6-OHDA was done as follows: 5 mg of 6-OHDA was dissolved in 1.0 ml of artificial CSF, and then injected into the cisterna magna. Seven days later, Nor or Oxy-Hb was applied. RESULTS: Pretreatment with reserpine tended to increase the vasoconstriction induced by 10(-7)-10(-4) M of Nor and the constriction induced by 10(-3) M of Nor was increased statistically (P less than 0.05). Cisterna magna injection of 6-OHDA tended to increase the vasoconstriction induced by Nor. SGG tended to increase the vasoconstriction induced by 10(-7)-10(-4) M of Nor and at a dose of 10(-3) M of Nor, the constriction of the basilar arteries was increased statistically (P less than 0.05). However, pretreatment with reserpine, 6-OHDA and SCG did not increase the vasoconstriction induced by Oxy-Hb. These results lead us to suggest that denervation supersensitivity does not participate in the vasoconstriction induced by Oxy-Hb.

[Experimental cerebral vasospasm induced by oxyhemoglobin and the sympathetic nervous system (Part 1): Effect of alpha-adrenergic receptor blockers].

This study was performed as part of a series of investigations into the relation between cerebral vasospasm following subarachnoid hemorrhage and the sympathetic nervous system. We studied the effect of phenoxybenzamine chloride (POB) and prazosin hydrochloride (Prazosin) on the cerebral vasoconstriction in the basilar arteries of cats induced by application of oxyhemoglobin (Oxy-Hb), noradrenaline (Nor) and prostaglandin F2 alpha (PGF2 alpha). Adult cats were anesthetized with intramuscular pentobarbital and maintained on a respirator through a tracheostomy. By the transclival approach, a bone window was formed in the clivus, and the dura was opened, exposing the basilar artery. A cannule was inserted into the subarachnoid space, and through it, Oxy-Hb, Nor and PGF2 alpha were injected. The sequential changes in caliber of the basilar artery were measured using photography. First, we determined the doses of POB and Prazosin necessary for decreasing the vasoconstriction induced by Nor, and 20 mg/kg of POB and 10 mg/kg of Prazosin were found to decrease the vasoconstriction induced by 10(-3) M Nor, statistically. Second, we investigated the effect of 20 mg/kg of POB and 0.5 mg/kg and 10 mg/kg of Prazosin on the cerebral vasoconstriction induced by Oxy-Hb or PGF2 alpha. POB (20 mg/kg) was infused for 2 hours before the application of Oxy-Hb or PGF2 alpha. Prazosin was given intravenously. In the first group, 0.02% Prazosin (0.5 mg/kg) was administered intravenously for 1.5 hours before the application of Oxy-Hb or PGF2 alpha. In the second group, 1.5 hours elapsed between the beginning of Prazosin (10mg/kg) infusion and the application of Oxy-Hb or PGF2 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous occlusion of traumatic carotid cavernous fistula after orbital venography.

A 50-year-old man was admitted to our hospital with a diagnosis of traumatic carotid cavernous fistula. The fistula was observed to disappear spontaneously just after orbital venography. This was confirmed by clinical examinations and subsequent carotid angiogram. The possible mechanisms responsible for the spontaneous occlusion of carotid cavernous fistula are discussed.

[Spontaneous cure of traumatic carotid cavernous fistula after orbital venography: case report].

A 50-year-old man with traumatic CCF was presented. Spontaneous cure with closure of the fistula occurred just after orbital venography and it was confirmed by clinical examinations and followed up carotid angiography. The possible mechanisms responsible for the spontaneous cure of CCF were discussed.