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Biomedical subjects

N Saeki

Publications and source records attributed to N Saeki.

At least 73 records · Page 4Linked to original sources
PubMed2000

Gamma knife radiosurgery as a primary treatment for prolactinomas.

OBJECT: The purpose of this study was to estimate the efficacy of gamma knife radiosurgery (GKS) in controlling tumor growth and endocrinopathy associated with prolactinomas. METHODS: Between 1993 and 1997, 164 of 469 patients with pituitary adenomas treated by GKS harbored prolactinomas. The dose to the tumor margin ranged from 9 to 35 Gy (mean 31.2 Gy), and the visual pathways were exposed to a dose of less than 10 Gy. The mean tumor diameter was 13.4 mm. The mean follow-up time for 128 cases was 33.2 months (range 6-72 months). Tumor control was observed in all but two patients who underwent surgery 18 and 36 months, respectively, after GKS. Clinical cure was achieved in 67 cases. Clinical improvement was noted with a decrease in the hyperprolactinemia after GKS. Nonetheless, in 31 (29%) of 108 patients who were followed for more than 2 years no improvement in serum prolactin levels was demonstrated, although this could be normalized by bromocriptine administration after treatment. Nine infertile women became pregnant 2 to 13 months after GKS and all gave birth to normal children. There was no visual deterioration related to GKS. Five women experienced premature menopause. In these patients there was subtotal disappearance of the tumor and an empty sella developed. CONCLUSIONS: Gamma knife radiosurgery as a primary treatment for prolactinomas can be safe and effective both for controlling tumor growth and for normalization of prolactin hypersecretion. A higher margin dose (> or = 30 Gy) seemed to be associated with a better clinical outcome. Gamma knife radiosurgery may make prolactinomas more sensitive to the bromocriptine.

Humans↗
PubMed2000

Albumin permeability across endothelial cell monolayer exposed to reactive oxygen intermediates: involvement of reversible functional alteration of the cell membrane Ca2+ channels.

This study was designed to test the idea that the redox state of sulfhydryl (SH)-groups in cell-membrane Ca2+ channels plays a pivotal role in Ca2+ influx, which in turn causes an increase in albumin permeability across the cultured monolayer of porcine pulmonary artery endothelial (PPAE) cells exposed to xanthine/xanthine oxidase (X/XO). Albumin permeability as well as the concentration of intracellular Ca2+ ([Ca2+]i) was increased by X/XO. A H2O2 scavenger (catalase), an iron chelator (o-phenanthroline), and a hydroxyl radical scavenger (dimethyl sulfoxide) inhibited these changes provoked by X/XO, in which intracellular iron-catalyzed hydroxyl radical generation was suggested to be involved. The increase in albumin permeability and [Ca2+]i continued once the PPAE cells were exposed to X/XO. The [Ca2+]i was decreased by a Ca2+ channel blocker, Ni2+, while the removal of Ni2+ increased [Ca2+]i again, suggesting the sustained Ca2+ influx through cell-membrane Ca2+ channels was responsible for the [Ca2+]i elevation. Ni2+ failed to inhibit albumin permeability sustained after the removal of X/XO. In contrast, SH-reducing agents (dithiothreitol and glutathione) inhibited the sustained permeability as well as Ca2+ influx. We concluded that the redox alteration of SH-groups in cell-membrane Ca2+ channels was involved in the increase in albumin permeability after exposure of the endothelial cells to oxidative stress.

Albumins↗
PubMed1999

MRI of growth hormone-secreting pituitary adenomas: factors determining pretreatment hormone levels.

Preoperative serum growth hormone (GH) level is one of the most important determinants of outcome. Our aim was to assess MRI findings which may correlate with pretreatment GH levels in GH-secreting adenomas. We retrospectively studied 29 patients with acromegaly caused by a pituitary adenoma. Tumor size (height, width, thickness and volume), suprasellar extension, sphenoid or cavernous sinus invasion, signal intensity and contrast enhancement were studied. Linear regression analysis or Fisher's exact probability test was used for statistical analysis. Factors related to high GH levels were the maximum dimension of the tumour (r = 0.496, P < 0. 01), its volume (r = 0.439, P < 0.05), spenoid sinus invasion (P < 0. 01) and intracavernous carotid artery (encasement (P < 0.01). The other items were not related to serum GH levels. Since we believe surgery is the first choice of treatment and the cavernous sinus is difficult of access with a conventional surgical approach, preoperative assessment of invasion into the cavernous sinus is critical for predicting the surgical outcome. Low GH levels (5-50 ng/ml) were found with tumours medial to the intercarotid line and high levels (more than 101 ng/ml) with invasive tumours with carotid artery encasement. Variable GH levels were noted with tumours extending beyond the intercarotid line. Because functioning adenomas invading the cavernous sinus tend to have markedly high hormone levels, and only patients with carotid artery encasement showed markedly elevated GH levels, we believe carotid artery encasement a reliable MRI indicator of cavernous sinus invasion.

Acromegaly↗
PubMed1999

Delayed postoperative CSF rhinorrhea of intrasellar arachnoid cyst.

CSF rhinorrhea due to a transsphenoidal approach usually follows accidental or intentional arachnoid opening. We report a patient with an intrasellar arachnoid cyst, who developed delayed onset of CSF rhinorrhea. A sixty-two-year-old man presented with bitemporal type visual field defect for the last 3 years. With the diagnosis of arachnoid cyst or Rathke's cleft cyst, based on MRI findings of intra-and supra-sellar cyst with CSF intensity, he successfully underwent transsphenoidal surgery without evidence of intra-operative CSF leakage. He developed CSF rhinorrhea one week later. This needed another operation for sellar floor repair. The pathomechanism of this delayed onset is explained as follows. Incomplete or oneway communication of subarachnoid space to cyst cavity, unrecognized during surgery, might cause delayed onset of CSF rhinorrhea. By using MRI, identification of the residual gland, which was compressed posteriorly, is useful for differentiating an arachnoid cyst from other cystic lesions. In highly suspect cases, even without evidence of intra-operative CSF leakage, peri-operative measures to prevent occurrence of postoperative CSF rhinorrhea are required.

Arachnoid Cysts↗
PubMed1999

Spontaneous disappearance of temporo-frontal arachnoid cyst in a child.

We report a child with a large temporo-frontal arachnoid cyst which resolved spontaneously. There was no history of a head injury. The patient was a boy aged 1.6 years. Though a large head was pointed out (+2SD), no therapeutic intervention was made because the relationship of the head circumference and the cyst was not established. No change in cyst size was visualized on the follow-up CTs at the age of 2.5 years and 6 years. At the age of 7 years, the arachnoid cyst had completely disappeared on CT. In order not to overlook a minute change in cyst size, the volumetry of the cyst and the intracranial cavity was performed, using the Photoshop, Macintosh. Both the cyst volume and the volume ratio of the cyst to the intracranial cavity slightly decreased and then increased. It is speculated that the cyst spontaneously ruptured by factors such as extreme breath holding and crying on the presence of the higher intracystic tension which might become a factor to accelerate spontaneous rupture of the cyst. Since a number of paediatric cases of symptomatic arachnoid cysts in need of surgical intervention has been larger than that of adult cases, we can speculate that a large arachnoid cyst might spontaneously resolve more frequently than we had expected. This case demonstrates that the surgical treatment of asymptomatic arachnoid cyst in the middle cranial fossa is not necessarily indicated in children.

Arachnoid Cysts↗
PubMed1999

MRI findings and clinical manifestations in Rathke's cleft cyst.

We retrospectively analysed patients with histologically proven Rathke's cleft cyst (RCC) in relation to the clinical manifestations and MRI findings, in particular, of cyst size and intensity in order to obtain an insight into their growing mechanisms, clinical presentations and their management. Eleven patients with RCC were divided into two groups based on T1 weighted images(WI). The A group consisted of 4 patients with cyst of low intensity in T1 WI. The age averaged 64.5 years. Their initial complaints were visual field defects(VFD). Their complaints were rather insidious. The maximum cyst size averaged 27.8+/-2.4 mm. The B group consisted of 7 patients with cyst of iso- or high-intensity in T1 WI. Two patients in the B group showed mixture of low and high and iso- and high-intensity, suggesting the presence of bleeding at the onset of symptoms or growing mechanism of the cysts. In the B group the age averaged 39.9 years, being lower than that in the A group. (P=0.0140 with Mann-Whitney's U test) The 5 patients out of 7 showed headache of insidious type or acute onset and the 3 showed a fluctuation of the VFD. The average size was 21.7+/-3.5 mm and smaller than that of the A group. (P=0.0298 with Mann-Whitney's U test) Our study has shown that the cyst with iso-to high intensity on T1 WI may cause clinical symptoms with a smaller size than cysts of the low intensity. In the former cyst pattern the onset and growing mechanism may be related to bleeding. The patients with this pattern are more likely to have acute and/or fluctuation of clinical presentations. Knowing these various clinical manifestations based on MRI pattern will be of help in following and managing patients with RCC.

Adult↗
PubMed1999

Unusual cranial nerve palsy caused by cavernous sinus aneurysms. Clinical and anatomical considerations reviewed.

BACKGROUND: Two cases of intracavernous internal carotid artery aneurysm with unusual clinical findings are reported. The pathomechanism and clinical significance are discussed. CASE DESCRIPTION: The first patient was a 49-year-old woman who presented with 6th nerve palsy and Horner's syndrome caused by a posteriorly located intracavernous aneurysm. The symptoms improved gradually in proportion to the size of the aneurysm. The second patient was a 69-year-old woman with isolated oculomotor superior division palsy caused by an anteriorly located large aneurysm. CONCLUSION: In the first case, a local aneurysmal compression at both the 6th nerve and the sympathetic fibers sent from the plexus on the intracavernous internal carotid artery is the most probable explanation. In the second case, the aneurysm might have selectively compressed the superior division of the oculomotor nerve at the anterior cavernous sinus. Clinical recognition of these syndromes results in a better diagnostic orientation. The authors discuss the pertinent anatomy and pathophysiology of the lesions because these findings are rarely seen clinically or in the literature.

Abducens Nerve↗
PubMed1999

Effect of pituitary microsurgery on acromegaly complicated nephrotic syndrome with focal segmental glomerulosclerosis: report of a rare clinical case.

A case of nephrotic syndrome complicated by acromegaly is presented. The first renal biopsy specimen showed minor glomerular abnormalities with glomerular hypertrophy, corresponding with minimal change nephrotic syndrome. Corticosteroid therapy led to a partial remission, followed by frequent relapses after reduction of the drug. A diagnosis of atypical focal segmental glomerulosclerosis (FSGS) was made based on the second renal biopsy results 6 months after the first. We combined steroid therapy with the administration of an anticoagulant, cytotoxic agents, angiotensin-converting enzyme inhibitor, and low-density lipoprotein adsorption. Except for the angiotensin-converting enzyme inhibitor, these medications were not effective in terms of allowing a reduction in the high dosage of steroid, which in turn threatened progressive osteoporosis and lumbar vertebrae fracture. Administering the steroid at a moderate dosage, treatment was focused on the complicating acromegaly from pituitary microadenoma. Subcutaneous injections of octreotide acetate, a somatostatin analogue, reduced proteinuria and increased urine volume. Subsequent transsphenoidal microsurgery of the adenoma resulted in the normalization of the elevated creatinine clearance and the further reduction in steroid dosage while maintaining a remission state. This is the first reported clinical case with acromegaly followed by FSGS, and it is suggested that hypersecretion of growth hormone participates in the development and progression of glomerular disease.

Acromegaly↗
PubMed1999

Cytosolic Ca2+ movements of endothelial cells exposed to reactive oxygen intermediates: role of hydroxyl radical-mediated redox alteration of cell-membrane Ca2+ channels.

1. The mode of action of reactive oxygen intermediates in cysosolic Ca2+ movements of cultured porcine aortic endothelial cells exposed to xanthine/xanthine oxidase (X/XO) was investigated. 2. Cytosolic Ca2+ movements provoked by X/XO consisted of an initial Ca2+ release from thapsigargin-sensitive intracellular Ca2+ stores and a sustained Ca2+ influx through cell-membrane Ca2+ channels. The Ca2+ movements from both sources were inhibited by catalase, cell-membrane permeable iron chelators (o-phenanthroline and deferoxamine), a *OH scavenger (5,5-dimethyl-1-pyrroline-N-oxide), or an anion channel blocker (disodium 4, 4'-diisothiocyano-2, 2'-stilbenedisulphonic acid), suggesting that *O2- influx through anion channels was responsible for the Ca2+ movements, in which *OH generation catalyzed by intracellular transition metals (i.e., Haber-Weiss cycle) was involved. 3. After an initial Ca2+ elevation provoked by X/XO, cytosolic Ca2+ concentration decreased to a level higher than basal levels. Removal of X/XO slightly enhanced the Ca2+ decrease. Extracellular addition of sulphydryl (SH)-reducing agents, dithiothreitol or glutathione, after the removal of X/XO accelerated the decrement. A Ca2+ channel blocker, Ni2+, abolished the sustained increase in Ca2+, suggesting that Ca2+ influx through cell-membrane Ca2+ channels was extracellularly regulated by the redox state of SH-groups. 4. The X/XO-provoked change in cellular respiration was inhibited by Ni2+ or dithiothreitol as well as inhibitors of Haber-Weiss cycle, suggesting that Ca2+ influx was responsible for *OH-mediated cytotoxicity. We concluded that intracellular *OH generation was involved in the Ca2+ movements in endothelial cells exposed to X/XO. Cytosolic Ca2+ elevation was partly responsible for the oxidants-mediated cytotoxicity.

Animals↗
PubMed1999

Transsphenoidal reoperations for removal of pituitary adenomas: rhinological management and timing of reoperation.

Transsphenoidal reoperation of pituitary adenomas remain a difficult surgical procedure even with skilful microsurgical techniques. This paper retrospectively analysed how to overcome such difficult factors as absent normal surgical landmarks and an adhesive field. For residual or recurrent adenomas, transsphenoidal reoperations were carried out 14 times in 12 patients. Reasons for reoperations were intentionally multistaged operations in 10 cases, regrowth in three and apoplexy in one. In the first operation, we tried to preserve or restore as many anatomic landmarks as possible. Overly aggressive procedures causing cerebrospinal fluid leakage were avoided. In the three second reoperations within 3 months, a transnasal approach was used. In the other eight situations, between 4 and 119 months, transnasal approach in five, and transseptal approach in three, were used retrospectively. In two patients with fibrous adenomas, reoperations were carried out 4 and 12 months after the first. Magnetic resonance imaging (MRI) evaluation is essential to confirm the tumour descent toward or into pituitary fossa. Timing of the reoperation needs to be individualized depending on MRI findings. Trauma to the nasal mucosa and a narrower operative field became more frequent in reoperations 4 months or later. To obtain a surgical field wide enough to manipulate an ultrasonic aspirator for fibrous adenomas, removal of bony structures at the nasal cavity on the surgical corridor is useful. These rhinological preparations in the first and subsequent operations along with a selection of timing of reoperation are important to gain easier access for tumour removal and in avoidance of surgical complications. Copyright 1999 Harcourt Publishers Ltd.

Journal Article↗
PubMed1999

Glucose and methionine uptake and proliferative activity in meningiomas.

Despite similar benign histological appearances, proliferative activity of meningiomas varies tumor to tumor, and even region to region in a tumor. To predict proliferative potential before surgery, we compared regional uptake of 2-[18F]fluoro-2-deoxyglucose ([18F]FDG) and L-[methyl-11C]methionine ([11C]MET) with histological indices of tumor proliferative activity in 17 specimens from six patients with meningioma obtained by PET guided stereotactic biopsies. Uptake of [11C]MET, an index of protein synthesis rate, significantly correlated not only with the count of nucleolar organizer regions (NORs), a histological index of protein synthesis, but also with Ki-67 index, a histological index of proliferative activity. On the other hand, [18F]FDG uptake showed no significant correlation with Ki-67 index or clinical malignancy. These results suggest that [11C]MET-PET is a useful tool for predicting tumor proliferative potential in meningiomas.

Adult↗
PubMed1999

Topographical analysis of proliferating cells in meningiomas. Regional heterogeneity of the ability of tumors to proliferate.

Regional heterogeneity of the ability of tumors to proliferate has been pointed out, but its topographical analysis has not been studied in detail. To evaluate the distribution of highly proliferating cells in totally resected meningiomas, seven cases (including one recurrent case) were investigated in this study. Immunostaining of PCNA was performed on the sections crossing the equator of the tumors. These sections were divided into multi-squares with sides of 500 micrometers. The proliferating potential was determined as the PCNA positive cell count in each square. By painting those squares in eight kinds of color corresponding to the value of the PCNA positive cell count, maps of proliferative ability were made. To predict the localization of proliferating cells, we studied these maps in relation to the following: MR image, calcification, distance from the dural attachment and distance from the tumor capsule. Maps of the PCNA positive cell count showed the intra-tumoral heterogeneity of proliferative ability in all cases. Most of the cases showed homogeneous enhancement on MRIs and these images could not be a predicting factor of the highly proliferating area. There was no significant relationship between the calcification and the PCNA positive cell count. Although the proliferating ability was not correlated with the distance from the dural attachment, inner regions distant from the capsule showed higher proliferative ability in all cases. From these results, one should be aware that the information from the samples of meningiomas do not reflect the proliferating ability of the whole tumor.

Aged↗
PubMed1999

Bone window CT evaluation of the nasal cavity for the transsphenoidal approach.

Bone window CT findings sliced parallel to the transsphenoidal surgical route were evaluated preoperatively in 104 patients with pituitary lesions in order to assess their clinical significance. (1) The width and depth of the transsphenoidal operative fields were measured. The piriform aperture was 26.3 mm (SD 2.5) in maximum width, the origin of inferior nasal concha 27.0 mm (SD 2.5) and the origin of the middle nasal concha 26.8 mm (SD 3.8), respectively. The distance between the piriform aperture and the sellar floor was 61.6 mm (SD 3.6). The operative field was cylindrical in shape, approximating 26-27 mm in width and 62 mm in depth. (2) The width and length of bony nasal cavity were different by 2-3 mm in patients with and without acromegaly. (3) In re-operated patients, the location of thinned or atrophic nasal mucosa, residual bony septum and narrow sellar floor opening, which needed further bony removal were demonstrated. Bone window CT provides direct visualization of the nasal anatomy for the approach, and is useful in screening for patients with a narrow nasal cavity. It helps to determine rhinological manoeuvres for providing wide operative fields at the nasal cavity and sellar floor.

Acromegaly↗
PubMed1999

Collapsibility of passive pharynx in patients with acromegaly.

Sleep-disordered breathing (SDB), either central or obstructive in nature, is common in patients with acromegaly. However, no study has systematically examined the collapsibility of the pharynx in acromegaly to date. We evaluated intrinsic mechanical properties of passive pharynx in 10 anesthetized and paralyzed patients with active acromegaly before transsphenoidal adenomectomy for their pituitary adenoma. Static pressure-area relationships of the velopharynx and oropharynx were obtained by step changes in airway pressure during endoscopic cross-sectional area measurement of each segment. Moreover, curve fitting analysis by an exponential function estimated the closing pressure (P'close) of each segment. Preoperative nocturnal oximetry identified five acromegalic patients with an oxygen desaturation index (ODI) greater than 10 h-1 and clinical symptoms suggesting presence of SDB. The pharyngeal airway of all five acromegalic patients with SDB was highly collapsible at both velopharynx and oropharynx with positive P'close. Compared with age-, body mass index (BMI)-, and ODI-matched SDB patients without acromegaly, SDB patients with acromegaly had a higher P'close of the oropharynx, indicating that the etiology of SDB in acromegaly appears to differ from that of ordinary sleep apnea. Our results suggest that anatomic abnormality, especially at the base of the tongue, appears to play a significant role in development of SDB in acromegaly.

Acromegaly↗
PubMed1999

MRI detection of suprasellar germinoma causing central diabetes insipidus.

This is a case report of an 18-year-old man with central diabetes incipidus (DI). An MRI done three months after the onset of the DI did not disclose a responsible lesion. Four months later, a second MRI showed the location of the tumor origin at the upper pituitary stalk and median eminence. Eight months later, the tumor occupied the hypothalamic area. The tumor became large and contrast-making enough to be visible on MRI between 3 and 4 months after the onst of DI. Besides the suprasellar tumor, another mass was noted in the pineal region. The growth pattern of the latter mass corresponded well to that of the former. Although the MRI is a sensitive diagnostic tool for the detection of intracranial tumors, no adequate rationale has been given as to how the MRI might be repeated for children and adolescents who have been diagnosed as having the central DI, when their initial MRIs may have been normal. In our patient, the superconductive thin slice MRI revealed the suprasellar germinoma 4 months after the onset. The suprasellar and pineal tumors in this report originated and developed simultaneously. This may indicate a multi-center origin of the tumor. Another possibility is a very early dissemination from the onset of the tumor development.

Adolescent↗