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Biomedical subjects

N Saeki

Publications and source records attributed to N Saeki.

At least 19 recordsLinked to original sources
PubMed2005

Gamma knife surgery for brain metastases: indications for and limitations of a local treatment protocol.

OBJECTIVE: The purpose of this retrospective study was to evaluate results of a local treatment protocol using gamma knife surgery (GKS) for brain metastases without upfront whole brain radiation therapy (WBRT). METHODS: Results for 521 consecutive patients satisfying the following 3 criteria were analysed: 1) a maximum of 3 tumours with a diameter of 25 mm or more; 2) no prior WBRT; 3) no surgically in accessible large (>30 mm) tumours. Large tumours were surgically removed and all smaller lesions were treated by GKS without up front WBRT. New lesions, detected with follow-up MRI, were appropriately treated with repeat GKS. Overall survival (OS), neurological survival (NS), qualitative survival (QS) and new lesion-free survival (NLFS) curves were calculated and the prognostic values of covariates were obtained. OS and NS were compared according to tumour number. RESULTS: In total, 1023 separate sessions were required to treat 4562 lesions. The primary organs were lung in 369 patients, gastro-intestinal tract in 70, breast in 33, urinary tract in 24, and others/unknown in 25. The median OS period was 9.0 months. On multivariate analysis, the significant prognostic factors for OS were found to be extracranial disease (risk factor: active), Karnofsky performance status (KPS) score (<70) and gender (male). NS and QS at one year were 85.6% and 73.0%, respectively. The only significantly poor prognostic factor for NS was carcinomatous meningitis. NLFS at 6 months was 68.9%. For both OS and NS, the differences between a few (</=3) and many (4-10) brain lesions were not significant (OS: p=0.3128, NS: p=0.5509). Patients with numerous (>10) tumours had a significantly poorer prognosis than those with </=10. CONCLUSION: Our protocol, aggressively applying GKS, provides excellent results in selected patients with </=10 brain lesions and no carcinomatous meningitis.

Aged↗
PubMed2003

MRI of ectopic posterior pituitary bright spot with large adenomas: appearances and relationship to transient postoperative diabetes insipidus.

MRI of large pituitary adenomas has revealed that a posterior pituitary bright spot (PPBS), comprising ADH-containing neurosecretory granules, is commonly ectopic before surgery and attached to the tip of the pituitary stalk late after surgery. Although the PPBS indicates functional integrity of the posterior lobe, transient diabetes insipidus (DI), caused by deficiency of ADH, is frequent early after surgery. We attempted to clarify how the shape, signal intensity and site of the PPBS before surgery are related to transient DI in the early postoperative period. We carried out MRI on 15 patients with a large adenoma and an ectopic PPBS before surgery and then within 1 week (early), 1-2 months (intermediate) and 6 or more months (late) after the operation. There were nine who had transient DI, which subsided by the intermediate study; none had permanent DI. Regardless of transient DI, the PPBS was visible, and its signal intensity was similar, on all postoperative studies. Although 11 did not change in shape, four showed a remarkable change from a flat shape before surgery to a rounded one postoperatively. On the intermediate MRI, the PPBS had descended to the level of the diaphragma as mass effect disappeared.

Adenoma↗
PubMed2003

Temporal parenteral nutrition in children causing t1 shortening in the anterior pituitary gland and globus pallidus.

Patients receiving long-term parenteral nutrition (PN) with trace elements (TE) may exhibit T (1) shortening in the anterior pituitary gland and basal ganglia. The purposes of this study were to clarify at what time or from what site the signal change begins in children. Retrospective analysis of magnetic resonance imaging results was performed for 10 pediatric patients aged from 1 to 16 years receiving temporal PN, eight of which received PN with TE for less than two months, and 13 patients with headache or seizures as age-matched controls. Axial and sagittal T (1)-weighted images were obtained to analyze the T (1) shortening in the anterior pituitary gland and globus pallidus. All eight patients receiving PN with TE exhibited T (1) shortening in the anterior pituitary gland (six patients) and/or globus pallidus (five patients). No T (1) shortening was observed in the other two patients without TE, or the 13 age-matched controls. Therefore, the signal change may be associated with TE administration, and begins markedly earlier than previously reported. We discussed the possibility that manganese (Mn) caused the signal change, and proposed that the administration of a lower dose of Mn is recommended, even in the case of temporal PN, to prevent possible Mn toxicity toward both the brain and liver.

Adolescent↗
PubMed2002

Heavily T2 weighted MR images of anterior optic pathways in patients with sellar and parasellar tumours - prediction of surgical anatomy.

OBJECTIVE: Location of anterior optic pathways in sellar and parasellar tumours was preoperatively evaluated, by use of heavily T2 weighted MR images. METHODS: Heavily T2 and conventional T1 weighted images were studied in 20 patients with sellar and parasellar tumours who underwent craniotomy. Pathology revealed pituitary adenoma in 5 patients, craniopharyngioma in 8 and parasellar meningioma in 7. Maximum sizes ranged from 15 mm to 58 mm. Sequence parameters of TR/TE for heavily T2 weighted and T1 weighted images were 5800/220 msec and 600/20 msec, respectively, and slice thickness was 3 mm for both. RESULTS: The anterior optic pathway was detected in 95% on heavily T2 weighted images and 50% on T1 weighted images. All preoperative heavily T2 weighted images were compatible with operative findings. The optic chiasms were most commonly supero-posterior in pituitary adenomas, anterior (prefixed) in craniopharyngiomas and posterior in meningiomas. The optic nerves were commonly located superior or lateral to the tumours. However, parasellar meningiomas, off the midline, revealed the optic nerves in various locations, depending on the tumour origin. In such tumours, heavily T2 weighted images provided surgical information on the width of the working space through prechiasmal and/or optico-carotid spaces in the pterional approach. Spatial relation of the tumours to the lamina terminalis, anterior commissure and anterior communicating artery complex was clearly shown in craniopharyngioma patients, who underwent the anterior interhemispheric approach. CONCLUSION: Heavily T2 weighted MR images are useful in determining the location of optic pathways and surgical approach and in individual prediction of the anatomy for even large sellar and parasellar tumours.

Adenoma↗
PubMed2002

Criteria for early detection of temporal hemianopia in asymptomatic pituitary tumor.

PURPOSE: To determine new criteria for early detection of temporal hemianopia in patients with asymptomatic pituitary tumor. METHODS: Fifteen patients without visual symptoms had pituitary tumor and subtle defects or normal visual fields by Goldmann perimetry. Twelve patients with visual symptoms had pituitary adenoma and visual field defects detected by Goldmann perimetry. All were examined by automated perimetry. The relationship between the tumor and the optic chiasm was graded by magnetic resonance imaging (MRI) on a scale of 0-4. Grade number increased with extent of compression. Temporal hemianopia observed by automated perimetry was estimated from normal data (52 normal fields). Vertical step was determined from the number of adjacent pairs along the midline; sensitivity was lower in the temporal field than in the nasal field. Temporal depression was calculated by the quadrant sum of sensitivity. RESULTS: All patients with symptomatic pituitary adenoma had vertical step and temporal depression in the upper field. Nine of 15 patients without visual symptoms had vertical step or temporal depression. Of nine patients with temporal hemianopia, two of four patients had grade 1 compression, three of five had grade 2, and four of four had grade 3. CONCLUSIONS: New criteria by automated perimetry could detect temporal hemianopia in patients with asymptomatic pituitary tumor.

Adenoma↗
PubMed2002

Demonstration of the optic pathway in large pituitary adenoma on heavily T2 weighted MR images.

The objective of the investigation was to understand preoperatively the detailed anatomical relationship of large pituitary adenomas to surrounding structures, using the heavily T2-weighted reversed (T2R) MR images. This study consisted of 28 patients with pituitary adenoma, presenting with visual disturbance. The MRI scanner used was a Gyroscan ACSNT 1.5T and the slice thickness of the image was 3 mm with 0.5 mm interslice gap. The relation of pituitary adenoma to optic pathway and to the degree of visual field defect was assessed. Relations of the optic chiasm to adenoma were classified into three types: anterior, superior and posterior. The optic chiasm was directly visualized and identifiable in all patients studied. It was located anterior in four cases, superior in 22 and posterior in two in relation to the adenoma. Its location was further confirmed by the anatomical delineation of surrounding structures such as anterior commissure and lamina terminalis. Optic nerve or tract was unidentifiable in one case, for each category. Detectability of each optic component was higher on T2R images than on conventional T1-weighted images. The adenoma extended into and in front of the third ventricle in anterior and posterior types, respectively. The anterior communicating artery complex and the optic pathway were relocated together in anterior and superior types, and were separated in the posterior type. In a case of the posterior type, the complex was sectioned to obtain a wider surgical field during anterior interhemispheric approach. While degrees of visual field defect were proportional to tumour size in the superior type, they were unrelated in the anterior and posterior types. On choosing a transcranial approach, the transcallosal route is unsuitable for an adenoma of posterior type, which extends in front of the third ventricle. This preoperative MRI information makes it possible to visualize directly the optic pathway even in huge adenomas, and is useful in predicting surgical anatomy and selecting a proper surgical approach.

Adenoma↗
PubMed2001

Potential role of the anterior spinal artery in preventing propagation of thrombus in a therapeutically occluded vertebral artery: angiographic studies before and after endovascular treatment.

Therapeutic occlusion of the vertebral artery (VA) is one of the treatments for unclippable aneurysms and other lesions, although controversy still surrounds the appropriate site for occlusion to attain selective thrombosis of the lesion while avoiding ischaemic complications. The lower two-thirds of the lateral medulla are supplied by perforating branches of both the VA and the posterior inferior cerebellar artery (PICA). However, in patients without a PICA or in whom the origin of the PICA is low (at or below the foramen magnum), the VA is usually the only source of perforating vessels. We retrospectively studied the results of VA occlusion on such anatomically high-risk patients, and propose a safer procedure. Five high-risk patients underwent therapeutic occlusion of the VA for dissecting aneurysms or arteriovenous fistula. A lateral medullary syndrome developed due to propagation of thrombus after the procedure in two patients in whom angiography did not demonstrate the anterior spinal artery (ASA) within the stump of the VA. Ischaemic signs did not develop in the other three patients, in whom the ASA was visible, and retrograde flow was observed proximal to the origin of the ASA. This suggests that the ASA may play a role in preventing propagation of thrombus in the VA distal to the site of occlusion and supply blood to its perforating arteries in high-risk patients. Angiographic assessment of the ASA may be useful for predicting the likelihood of the lateral medullary syndrome developing with therapeutic occlusion of the VA in patients without a PICA or with one whose origin is low.

Adult↗
PubMed2001

Hybridization between oxy-peptide nucleic acids and DNAs: dependence of hybrid stabilities on the chain-lengths, types of base pairs, and the chain directions.

Oxy-peptide nucleic acids (OPNAs) of [-NH-CH(CH2-CH2-Base)-CH2-O-CH2-CO-]-type main chain with four different types of nucleobases (Base = A, G, C, and U) or with an abasic side group (X) were synthesized. Melting curves of the 1:1 hybrids of o(A(n))-d(Tn)) pairs with n = 6, 9, 12, and 15 showed very sharp transitions at high Tm values, particularly for long chains, indicating that nearly optimum matching is attained in the structure of the o(A(n))-d(Tn) hybrids. Effect of different types of base pairs on the hybrid stabilities was examined for the o(A4NA4)-d(T4N'T4) 1:1 mixtures where N is A, G, C, U, or X and N' is A, G, C, or T. In all series of the hybrids the complementary pairs showed the highest Tm values. The Tm values of the complementary pairs were about 35 degrees C when purine bases were inserted as the N group in the OPNA, but they were 20-23 degrees C when pyrimidine bases were inserted. The melting curves of the hybrids with a single mismatch were similar to those with a single X-N' pair, suggesting that the mismatch base pairs have been ignored in the hybrids. All complementary OPNA-DNA hybrids showed higher Tm values and sharper transitions than the corresponding DNA-DNA hybrids. The OPNA-DNA hybrids favor a parallel direction i.e., the N-terminal of OPNA is directed to the 5'-terminal of DNA.

Base Pairing↗
PubMed2001

Maxadilan specifically interacts with PAC1 receptor, which is a dominant form of PACAP/VIP family receptors in cultured rat cortical neurons.

Maxadilan is a potent vasodilator peptide isolated from salivary gland extracts of the hematophagous sand fly. Recently, the possibility was demonstrated that maxadilan binds to PAC1 receptor (PACAP, pituitary adenylate cyclase activating polypeptide type I receptor) in mammals. In the present study, we demonstrated that: (1) maxadilan specifically binds to PAC1 receptor and stimulates cyclic AMP accumulation in a dose-dependent manner in CHO cells stably expressing PAC1 receptor, not VIP (vasoactive intestinal polypeptide) receptors; that (2) the deleted peptide (amino acid #24-42) of maxadilan (termed max.d.4) also specifically binds to PAC1 receptor although max.d.4 inhibits cyclic AMP accumulation stimulated by both maxadilan and PACAP; and that (3) max.d.4 completely blocks the cyclic AMP accumulation induced by VIP in cultured rat cortical neurons. The expression of specific PACAP receptors in cultured rat cortical neurons was further investigated by the reverse transcription-polymerase chain reaction technique, which showed the presence of mRNA coding for PAC1 receptor among PACAP/VIP family receptors. These data indicate that maxadilan and max.d.4 represent important tools for clarifying the physiological role of PAC1 receptor, and that PAC1 receptor plays an important role in the regulation of the functions induced by PACAP in rat cultured cortical neurons.

Amino Acid Sequence↗
PubMed2001

Demonstration of the postcommissural fibres of the fornix in short-inversion time inversion-recovery imaging on a high-field system.

Short-inversion time inversion-recovery (STIR) imaging using a 3 tesla system was assessed to reveal the postcommissural fibres (PF) of the fornix, which have rarely been highlighted neuroradiologically in the clinical setting. We studied 27 normal subjects. Sequence parameters were TR/TE/TI 8000/52/ 150 ms. STIR was expected to take advantage of the high signal-to-noise ratio of a high-field system, due to the long repetition time. PF were identifiable in axial and coronal slices in all cases. They were bordered anteriorly and superiorly by the anterior commissure and posteriorly and inferiorly by the mamillary body. Behind the anterior commissure, they ran in an arch-shaped posterior and inferior course in the hypothalamic nuclei and joined the mamillary body anterolaterally. They usually extended through three 3-mm slices (with 1 mm interslice gap) in anteroposterior and vertical dimensions. Little variation was observed in their course or size. Demonstration of the PF would provide a more detailed correlation of human neuroanatomy to hypothalamic function and individualised understanding of hypothalamic pathology and influence therapy.

Adolescent↗
PubMed2001

Computed tomography and magnetic resonance imaging of mild head injury--is it appropriate to classify patients with Glasgow Coma Scale score of 13 to 15 as "mild injury"?

OBJECTIVE: The purpose of this study is to examine the relation between Glasgow Coma Scale (GCS) score and findings on computed tomography (CT) and magnetic resonance (MR) imaging of patients with mild head injury presenting GCS scores between 13 and 15. METHODS: Data were collected from all consecutive patients with mild head injury who were referred to our hospital between July 1 and October 31, 1999. All patients were recommended to undergo CT and MR imaging examinations. Patients younger than 14 years of age were excluded. RESULTS: Ninety patients were recruited into this study. CT scans were obtained in 88 patients and MR imaging were obtained in 65 patients. Of these 90 patients, 2 patients scored 13 points, 5 scored 14 points and 83 (92.2%) 15 points. Patients with GCS score of 13 points demonstrated parenchymal lesions on both CT and MR imaging. Those with 14 points revealed absence of parenchymal abnormality on CT, but presence of parenchymal lesions on MR imaging. Patients in advanced age (chi square test, p<0.0001), and those with amnesia (p=0005, not significant), although scoring 15 points, revealed a tendency to abnormal intracranial lesions on CT scans. CONCLUSION: It is doubtful whether patients with GCS score 13 should be included in the mild head injury category, due to obvious brain damage on CT scans. MR imaging should be performed on patients with GCS score 14, since the parenchymal lesions are not clearly demonstrated on CT scans. Even if patients scored GCS 15, patients with amnesia or of advanced age should undergo CT scans at minimum, and MR imaging when available.

Adolescent↗
PubMed2001

Heavily T2 weighted MR assessment of fornical injury after anterior interhemispheric approach for large suprasellar tumors.

Fornical injury in transforaminal approach is well known. Its injury in the anterior interhemispheric approach (AIA) has been rarely highlighted. We report 2 cases with a large suprasellar tumor who underwent AIA. Postoperative heavily T2 weighted reversed (T2R) MR images demonstrated its unilateral injury. The clinical significance of symptom-free fornical injury after AIA is discussed. Cases 1 and 2 were a 15 year-old girl with a meningioma and a 49-year-old woman with a craniopharyngioma, respectively. They underwent AIA. Postoperative T2R images revealed unilateral fornical crus atrophy. They did not present associated memory deficits. Case 1 had the injury of both fornical column and anterior commissure. They were speculatively torn by intra-operative lateral retraction of the frontal lobes. Case 2 had unilateral atrophy of the mammillary body and postcommissural fornix, which were probably caused by ischemic damage related to surgical manipulation, since case 2 had an associated anterior thalamic infarct. During the operation for large suprasellar tumors, excessive laterally directed brain retraction should be avoided, since such manipulation may easily tear the overstretched anterior commissure and fornical column. Once we notice or suspect fornical injury on MR studies in cases of re-operation, we have to choose a surgical approach and operative manipulation to preserve an intact fornix. The MR evaluation of fornix should be included in the perioperative radiological assessment, since patients with unilateral fornical injury were free of memory disturbance, and T2R imaging is a useful MR sequence for depicting the anatomy related to the fornix.

Adolescent↗
PubMed2001

Influences of venous involvement on postoperative brain damage following the anterior interhemispheric approach.

BACKGROUND: The anterior interhemispheric approach offers us an excellent surgical view for suprasellar lesions. Following this approach, we occasionally encounter postoperative brain damage in the frontal lobes. To assess the determinants of such a complication, we undertook a clinical study. METHOD: Potential causes for such brain damage were evaluated in 28 consecutive patients with suprasellar tumours extirpated using this approach. We focused particularly on the influences of venous involvement during surgery. The draining territory index (DTI) was originally devised for estimating the extent of the draining area of the sacrificed bridging veins. FINDINGS: CT evident brain damage was observed in five of 28 patients (17.8%), but only one patient (3.6%) showed clinically significant postoperative deficits. The patient's age, tumour pathology, tumour character, tumour size, duration of surgery, and radicality of the surgery did not affect the incidence of the brain damage. Of the twelve patients whose bridging veins were sacrificed during surgery, four (33.3%) showed brain damage in the frontal lobes. In contrast, such damage was observed in only one patient out of 16 (6.3%) whose bridging veins were preserved. Among the brain-damaged group, the average DTI of the sacrificed veins was significantly higher than that among the non-brain-damaged group. INTERPRETATION: Venous involvement during surgery significantly aggravated postoperative brain damage following the anterior interhemispheric approach. The DTI was useful in predicting the risk of brain damage, and a large bridging vein with a DTI over 50% should not be sacrificed during surgery.

Adult↗