Takafumi Kodama

ADENOSINE KINASE OF MAMMALIAN BRAIN: PARTIAL PURIFICATION AND ITS ROLE FOR THE UPTAKE OF ADENOSINE

Abstract— Adenosine metabolism in the homogenate of brain mainly undergoes deamination to inosine and hypoxanthine, while uniformly labelled [14C]adenosine injected into the carotid artery or [8‐14C]adenosine incubated with brain slices was mostly phosphorylated to [14C]adenine nucleotides in brain cells. Adenosine kinase has now been partially purified from homogenates of guinea pig brain. The kinase preparation was free of adenosine deaminase, almost free of adenosine triphosphatase and had a Km of the order of 2 × 10‐5M for adenosine.

The cyclic AMP system of human brain

In the cortical gray matter of human brains, which were obtained by permissible resection at the time of surgery, cyclic 3′, 5′-AMP was found in a range of concentrations between 42 and 143 pmole/mg protein. The subcortical white matter and various types of brain tumor contained much lower concentrations of the nucleotide. The level of the cyclic nucleotide in incubated slices of gray matter was elevated 20–50-fold by norepinephrine (0.5–1.0 mM) or veratridine (0.05 mM), 4–7-fold by histamine (1.0mM) or adenosine (0.2mM) and 1.5–2-fold by serotonin. With respect to the stimulatory effect on the cyclic AMP level in human brain slices, norepinephrine was inferior to epinephrine or isoproterenol, and was completely antagonized with a β-adrenergic blocking agent, propranolol, but only slightly by α-blocking agents, such as phentolamine and dibenamine. The particulate fraction of human brain homogenate was capable of synthesizing cyclic AMP from ATP. This enzymic activity was 0.19–0.24 nmole/min/mg protein. This activity was stimulated 2–3-fold by the addition of 10mM NaF but not by any of the biogenic amines tested. The activity of nucleotide phosphodiesterase of human brain was almost equal to that of rat brain: only a single Km for the substrate cyclic AMP was observed around 0.9 × 10−4M.

Stimulated formation of adenosine 3′,5′-monophosphate by desipramine in brain slices

Abstract The effect of five tricyclic psychotropic drugs on the formation of adenosine 3′,5′-monophosphate (cyclic AMP) was examined using guinea pig cerebral slices which had been preincubated with [8-14C]adenine to label a proof of intracellular ATP. Three antidepressants, i.e. imipramine, desipramine, and amitriptyline elevated the level of cyclic [14C]AMP and increased the relative formation of cyclic [14C]AMP in the slices more than 5-fold. Two tranquilizers, chlorpromazine and perfenazine had little effect. The effect of desipramine was maximal at 0.5 mM, was blocked by 1.0 mM theophylline by more than 80%, and was not inhibited by either phentolamine or propranolol.

Large Infratentorial Multilocular Arachnoid Cyst

Clinical and radiological findings in a 2-year-old boy with a large multilocular infratentorial arachnoid cyst are presented. The cyst was extended in the bilateral paracollicular and retrocerebellar region and was communicating with each other but not with the ventricular system. Associated with those cysts was a significant degree of hydrocephalus due to compression of the fourth ventricle. Delayed metrizamide CT scan showed totally isolated cysts from CSF circulation although the cystic content was determined as the CSF.

Acoustic schwannoma presenting as subarachnoid hemorrhage due to ruptured contact aneurysm

The authors report a rare combination of aneurysm and acoustic schwannoma in a 66-year-old housewife, who developed subarachnoid hemorrhage from a ruptured aneurysm arising from an arterial branch of the posterior inferior cerebellar artery on the tumor capsule. Association of aneurysm and cerebellopontine angle schwannoma is extremely rare, and there has been no report of subarachnoid hemorrhage due to ruptured contact aneurysm, although previous reports indicated a small number of acoustic schwannomas accompanying hematomas in and around tumors.

Analysis of Cerebral Blood Circulation using Intravenous Digital Subtraction Angiography

Digital subtraction angiography with intravenous injection of contrast medium was used to assess 10 patients with ischemic disease. The time-density curve (TDC) was evaluated for its usefulness in analyzing brain blood circulation (dynamics). Such other parameters as peak time (PT), mean transit time (MTT), and mode of transit time (MOTT) were also assessed. Particular attention was paid to high convexity, watershed, and perforator areas of the middle cerebral artery, which are regions of interest in the bilateral hemispheres. The dynamics of blood circulation demonstrated by this method were compared with those demonstrated by single photon emission computed tomography (SPECT). In patients with carotid artery stenosis, the TDC at the convexity area on the affected side showed both a gentle upward slope and a slow downward slope, and all parameters (PT, MTT, MOTT) were prolonged. After endarterectomy, the delay in all parameters decreased and the laterality of the TDC diminished. In patients with middle cerebral artery occlusion, the TDC at the convexity area on the affected side showed delay of attenuation, and all parameters were prolonged. After superficial temporal artery-middle cerebral artery anastomosis, the peak on the operated side was higher than that on the unaffected side and prolongation of MTT and MOTT on the affected side was decreased. In cases of moyamoya disease, none of the parameters could be calculated because the TDC showed no downward slope. In all of the evaluable cases, TDC data were superior to SPECT determinations in detecting laterality of the circulation. These results indicate that this method accurately demonstrates laterality of circulation time and volume as well as the degree of collateral circulation. The TDC and other parameters appear useful in determining whether or not surgery is indicated and in estimating the postoperative circulation in patients with ischemic disease.

Neuroradiologic findings of hypothalamic hamartoma with emphasis on computed tomography.

Hypothalamic hamartoma is a relatively rare congenital malformation. Five new cases and 31 cases in the literature were evaluated in regard to neuroradiologic findings with emphasis on computed tomography. Five important computed tomography findings were observed: oval-shaped, isodense suprasellar mass; clear demarcation; no enhancement effect; absence of cystic component or calcification; and no effacement of the third ventricle. Clinical features, mechanism of the precocious puberty, and differential diagnosis are also discussed.

The Quantitative Analysis of Psychiatric Sequelae after Direct Surgery of Anterior Communicating Aneurysms

Follow-up study of 50 cases with directly operated anterior communicating aneurysm was made, ranging from 6 months to 5 years and 6 months. Forty six cases were alive and the condition of all these cases was evaluated through questionnaires, and 42 cases of them were examined utilizing the WAIS and Y-G test. Four patients out of 46 cases showed decreased ADL and they needed help in their daily activity. About 60% of the cases have resumed full activity of previous occupation, although 68% of the 46 cases have complained of slight headache, forgetfullness and worries about their illness being never cured. The number of cases with the above complaints decreased markedly 2 years after surgery was performed. Verbal IQrecovered sooner than Performance IQobtained on WAIS, and the profile of recovery showed quite a resemblance in the repeated WAIS. Comparing pre and post-operative cases in short term the cause of the poor IQ at present study was considered due to subarachnoid hemorrhage itself rather than to surgical intervention. Poor preoperative condition, such as grade III, IV, of Hunt and Hess, showed delay in recovery. There was no definite evidence of disturbing IQrecovery by angiospasm, ventricular dilatation, direction of aneurysm etc., as far as preoperative grade I, and II groups were concerned. The ultimate evaluation of the patient in regard to social adaptability from IQ test required a 2 year period. Symptoms of so called normal pressure hydrocephalus due to subarachnoid hemorrhage showed sometimes remarkable recovery of the mental state after shunt operation, but in other cases, shunt procedure failed to show persistent effect and several patients showed good IQ in the follow-up study, although the shunt device lost patency in early stage of follow-up. Y-G test showed interesting fact that the cases of poor IQ, especially poor Performance IQ, assumed types of passive adaptability.