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Biomedical subjects

H Samejima

Publications and source records attributed to H Samejima.

31 records · Page 2Linked to original sources

Theoretical situation of brain white matter tracts evaluated by three-dimensional MRI.

An accurate knowledge of cerebral anatomy is important in order to evaluate the precise location of a cerebral lesion. Cortical structures are identified by knowledge of the adjacent gyri and sulci; however, white matter tracts are difficult to differentiate from one another due to the lack of clear anatomic landmarks. Therefore, even if MRI shows obvious white matter abnormalities, in some cases it is difficult accurately to localize the lesion. The purpose of this study is to evaluate the location of the main white matter tracts by using three-dimensional MR imaging. MRI study was performed by 1.5 Tesla (Signa: General Electric). Computer assisted analysis with Voxtool software (General Electric) was used to generate both surface brain and tomographic images. The exact anatomic basis of white matter signal abnormalities is important when analyzing patients with disconnective syndromes or neuropsychological deficits such as conduction aphasia, visuospatial deficit etc. This preliminary attempt at constructing a three-dimensional MRI white matter atlas of the brain may be helpful for evaluating the anatomico-clinical correlations in these patients, and also as teaching materials for the clinical (neurologic, neurosurgical), anatomic and radiographic disciplines.

Adult↗

[Antigenicity study on lactitol (NS-4)].

Lactitol hydrate (lactitol) was tested for its antigenicity in guinea pigs and mice. The following results were obtained. 1. No active systemic anaphylaxis reactions were found in guinea pigs sensitized subcutaneously with lactitol alone or in combination with Freund's complete adjuvant (FCA). 2. No 24 hr heterologous passive cutaneous anaphylaxis reactions were elicited in rats by sera from mice sensitized intraperitoneally with lactitol alone or in combination with 3% aluminum hydroxide gel. 3. No passive hemagglutination reactions were elicited by sera from mice sensitized subcutaneously with lactitol in combination with FCA. From these results, it is concluded that lactitol has no antigenicity under the present experimental conditions.

Anaphylaxis↗

[A quantitative approach to the rCBF response to acetazolamide using 99mTc-HMPAO and graphical analysis].

A simple noninvasive method for a quantitative measurement of brain perfusion is presented using intravenous radionuclide angiography with 99mTc-hexamethylpropylene amine oxime (HMPAO). Graphical analysis was employed for the evaluation of the unidirectional influx constant (ku) of the tracer from the blood to the brain and the initial distribution volume (Vn) for the tracer, which is the volume of the exchangeable region plus the plasma space. The ku and Vn values were standardized to provide objective and comparable values, brain perfusion indices (BPI) and corrected Vn (Corr. Vn), between subjects by setting the size ratio of ROI(brain) to ROI(aorta) at 10 and 1, respectively. BPI and Corr. Vn of the whole brain were measured before and 20 min after injection of 1 g acetazolamide. After acetazolamide administration, BPI and Corr. Vn increased in all eight subjects with cerebrovascular diseases and one with a pituitary adenoma, by a mean of x 1.26 and 1.24, respectively. Increase of BPI showed a significant correlation with increase of Corr. Vn. This technique is easy to apply as an adjunct to SPECT and may be helpful in the measurement of brain perfusion changes in the acetazolamide test.

Acetazolamide↗

[Acetazolamide effect on vascular response in crossed cerebellar diaschisis as measured by 99mTc-HMPAO SPECT].

We studied the effect of acetazolamine (DIAMOXR) on vascular response in areas with crossed cerebellar diaschisis (CCD) using consecutive 99mTc-hexamethyl-propyleneamine oxime (HMPAO) SPECT studies before and after DIAMOX administration with a subtraction method. Regions of interest were drawn over the bilateral cerebellar cortices and interhemispheric asymmetry indices (IAI) were obtained. Eleven of 14 patients with CCD at baseline showed decrease of IAI after DIAMOX administration. Although there is a possibility of underestimation of increase in perfusion in unaffected cerebellar hemisphere, this result suggests a greater increase in perfusion in the affected cerebellar hemisphere as compared with in the contralateral unaffected one and suggests more dilatation of the arterioles in areas with CCD post-DIAMOX than in areas without CCD. However nonsignificant correlation between IAI at baseline and difference of IAI from baseline to post-DIAMOX did not support the hypothesis of more dilatation post-DIAMOX of more constricted arterioles.

Acetazolamide↗

Demonstration of focal brain ischemia induced by hyperventilation using Tc-99m HMPAO SPECT.

A case with vasospasm of the right anterior cerebral artery induced by hyperventilation is presented. Consecutive Tc-99m HMPAO brain SPECT studies at rest and during hyperventilation greatly contributed to the quantitative evaluation of focal perfusion decrease in conjunction with contrast angiography. This technique seems to be useful for the detection of alterations in regional brain perfusion during short duration intervention.

Adult↗

New screening system for unruptured cerebral aneurysms--combination of an expert system and DSA examination.

We have designed a screening system to diagnose unruptured aneurysms, including the use of digital subtraction angiography (DSA). We surveyed 115 patients who had undergone clipping procedures after subarachnoid hemorrhage (SAH) and questioned them with regard to the subjective symptoms. Sixty-eight of 92 patients who returned the questionnaire reported, prior to rupture, headache, eye pain, and neck pain most frequently, and also impairment of extraocular movements, ptosis, visual field defects, and motor and sensory disturbances. Nineteen (47.5%) of 40 patients who had complete pain relief after surgery complained of headache from 1 week to 1 month before SAH. In addition, nine patients (22.5%) complained of headache for several years, and were also pain-free after surgery. For the indication of DSA, we employed an expert system based on fuzzy set theory. Seven groups of parameters are: Group 1, a basic questionnaire concerning age, sex, and past and family histories; Group 2, 15 warning signs selected on the basis of retrospective study; and Groups 3-7, detailed questions concerning each sign. Scoring weights assigned to each condition based on the results of the retrospective study, and threshold values were determined by several neurosurgeons. The certainty factors for intermediate hypotheses were calculated from these weights and threshold values and summed up, from which the conclusion was obtained. Twelve new cases of unruptured cerebral aneurysm were diagnosed using this screening system. This system may improve the ability to diagnose cerebral aneurysms before rupture.

Aged↗

[A mucin-producing cystadenoma, borderline malignancy, of the renal pelvis and ureter: a case report].

A cystadenoma or a cystadenocarcinoma arising from the renal pelvis is a rare neoplasma and, so far as is known, only two cases have been reported in the literature (Arcadi, 1956, and Ross, 1985). Discussed herein is a case of a 63-year-old woman who developed a mucinous nephrosis, due to a marked retention of mucin produced by a tumor. The ureter as well was found to be involved. The histogenesis of an adenocarcinoma, which includes a cystadenoma and a cystadenocarcinoma, most likely is due to a glandular metaplasia, associated with urolithiasis and pyelonephritis. In this specific case, the patient revealed a history, fifteen years earlier, of renal calculi and pyelonephritis.

Cystadenocarcinoma↗

[Studies on recurrence of cerebral aneurysm after operation].

It seems to be well established that the direct surgical treatment of intracranial aneurysm such as clipping, trapping and wrapping the aneurysm. These operations have brought about excellent results but are not perfect because recurrent aneurysm and rebleeding of aneurysm have been reported shortly after the operation. However, it is very rare that subarachnoid hemorrhage arising from recurrent aneurysm long time after the operation, authors have experienced 3 cases of recurrent aneurysm in the same region long after the surgery. Two cases were readmitted to our hospital following repeat episode of subarachnoid hemorrhage. Carotid angiogram showed a new small aneurysm locating about the same place where previously operated aneurysm was situated. One of them showed development of new aneurysm at the anterior communicating after 4 years artery the neck clipping, the other one was recurrent aneurysm 9 years after the neck clipping of aneurysm at the anterior communicating artery. Two cases were treated by reclipping and got well. It has been reported in the articles that 20 cases of recurrent aneurysm were located about the same place where previously clipping aneurysm was performed. Causes of such recurrence of already clipped aneurysm could be divided into two groups. First group was considered that the treatment was unsatisfactory, because the clip had been improperly placed. The other group was considered as mechanical failure of aneurysmal clip that resulted in "slipped out," or "broken clip", and local fragility of the arterial wall adjacent to clip edge. Last case had a giant pseudoaneurysm.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Electrochemical measurements of cell populations.

Determination of cell growth was carried out by a polarographic system. The system was constructed of two platinum electrodes, a saturated calomel electrode, and a thermistor electrode. Responses of the system to the dissolved oxygen, pH, and temperature were examined. Cell growth of S. cerevisiae and M. olivoasterospora was monitored continuously by this system. In addition, this polarographic system could be applied to the measurements of cell populations of the human cancer cell L-1210 and mouse leukocytes. The measureable range for these animal cells was approximately 10(3)--10(5) cells/ml.

Animals↗

Significance of pathognomonic features of normal-pressure hydrocephalus on computerized tomography.

In some patients with congenital or acquired hydrocephalus, a low-density area is seen around the lateral ventricle on computerized tomography. Above all, in patients with normal-pressure hydrocephalus following subarachnoid hemorrhage, there appears a specific low-density area which is fan-shaped and irregular and which extends from the bilateral anterior horns to the frontal pole. This disappears or decreases with a VP shunt. Improvement of clinical symptoms is proportional to the degree of disappearance of the low-density area. The essential part of the occurrence of symptoms in patients with normal-pressure hydrocephalus depends upon a low-density area on CT.

Brain Neoplasms↗

Posttraumatic epilepsy and CT scan.

Among 83 head-trauma cases examined by CT scan in a later year, 41 were included in a seizure group of those who clinically showed late epilepsy and who obviously showed epileptic discharge such as spike or spike and wave in EEG after trauma, and 42 were included in a nonseizure group of those who had some sequelae such as abnormal findings in EEG or neurologic defects: the CT findings of these 83 cases were collected and compared with clinical findings, EEG, and other data. The CT findings of these cases were divided into five groups: (A) a normal group; (B) a group showing partial or unilateral ventricular dilatation; (C) a group showing porencephaly in the cerebral parenchyma; (D) a group suspected of cortical atrophy; (E) a group of other cases. Group D contained 44.3% of the cases, and was the largest group; the frequency of seizure was highest in Group C. The CT classification reveals the contradiction of the conventional definition of posttraumatic epilepsy and also poses some problems concerning the disease. CT scan is mostly applied to head trauma in the acute stage, and as for trauma in the chronic stage there are a few reports on chronic subdural hematoma and post-traumatic hydrocephalus. We noticed posttraumatic epilepsy among the sequelae of trauma, and then analyzed CT findings of the epilepsy: the results are reported here.

Adolescent↗