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Biomedical subjects

M Kabuto

Publications and source records attributed to M Kabuto.

At least 91 records · Page 5Linked to original sources
PubMed1992

Corticotroph cell hyperplasia in a patient with Addison disease: case report.

A woman with Addison disease developed hyperpigmentation, headache, and nausea despite conventional replacement therapy with cortisone. Excessively elevated plasma adrenocorticotropic hormone (ACTH) with absence of response to administration of corticotropin-releasing factor (CRF), and roentgenological evidence of enlargement of the sella turcica, as well as detection of enlarged pituitary gland on magnetic resonance images, led to a diagnosis of ACTH-producing microadenoma, which was removed by transsphenoidal microsurgery. The specimen obtained at surgery evidenced corticotroph hyperplasia, as demonstrated by immunohistochemical staining for ACTH. Fine structure exhibited densely granulated cells with a few bundles of microfilaments and an abundance of large lysosomal bodies. Surgical removal of the hyperplasia alleviated the patient's symptoms, and hyperpigmentation faded remarkably. Her plasma ACTH level returned to normal, has remained normal for more than 3 years, and responds adequately to CRF administration.

Addison Disease↗
PubMed1992

An artificial blood vessel with an endothelial-cell monolayer.

An artificial blood vessel with an endothelial-cell monolayer was used as an arterial substitute in rats. Endothelial cells were isolated from the aorta of a Wistar rat by the digestion method. The cell identification was established by the cobblestone appearance of a confluent cell monolayer, by an expression of factor VIII-related antigen, and by the presence of Weibel-Palade bodies. The luminal surface of the thin-walled polytetrafluoroethylene (PTFE) graft (4 mm in diameter and 10 mm in length) was coated with an endothelial-cell monolayer for 7 days in vitro. An interpositional graft was placed using the endothelial cell-coated PTFE prosthesis on the right common carotid artery in seven rats. A total of 10 rats received an interpositional graft with the noncoated PTFE prosthesis as a control. The patency rate at 1 month after implantation was significantly higher in the coated group than in the control group. The vascular prosthesis with an endothelial-cell monolayer is a promising technique to inhibit the development of thrombosis.

Animals↗
PubMed1991

Serum ferritin and stomach cancer risk among a Japanese population.

Using stored serum samples collected during from 1970 to 1972 and/or 1977 to 1979 from a fixed population in Hiroshima and Nagasaki, Japan, serum ferritin, transferrin, and ceruloplasmin levels were determined immunologically for persons in whom stomach (233 cases) or lung cancer (84 cases) subsequently developed as well as for their controls. An elevated stomach cancer risk was associated with low antecedent serum ferritin levels, with more than a threefold excess among those in the lowest compared with the highest ferritin quintile. The risk did not vary with the time between blood collection and stomach cancer onset, remaining high among those with low ferritin levels 5 or more years before cancer diagnosis. Achlorhydria, diagnosed in a sample of the population about 10 years before the 1970-to-1972 blood collection and up to 25 years before cancer, was an independent marker of stomach cancer risk. In combination, low serum ferritin and achlorhydria were associated with a tenfold increase in the subsequent risk. No effect of transferrin or ceruloplasmin, independent of ferritin, was observed in the gastric cancer risk, and the risk of lung cancer was not related to these three serum proteins. These prospective findings indicate that biologic markers of an increased risk of stomach cancer can be detected long before cancer onset.

Achlorhydria↗
PubMed1991

Central neurocytoma: immunohistochemical and ultrastructural study.

Eight cases of central neurocytomas were studied by immunohistochemistry and electron microscopy. Seven tumors were located in the lateral ventricles and one in the subependymal region. All but one patient had a favorable postoperative course. The tumors were composed of small uniform cells possessing amitotic round nuclei with frequent perinuclear halos, a few Homer Wright rosettes and no ganglion cells; an appearance resembling that of oligodendroglioma. Immunohistochemical studies disclosed neuron-specific enolase and Leu-7 positivity in all tumors, S-100 protein-positive cells were found in six, while glial fibrillary acidic protein--and vimentin-positive cells were confined to the blood vessels. Myelin basic protein as well as neurofilament were not detected in the tumors. Synaptophysin-positive areas were seen in one tumor. Ultrastructural examination showed distinctive neuronal tumor cells which had a cytoplasm with sparse dense-core vesicles and thin cell processes containing parallel microtubules. They were classified into three different types of tumor cells according to the extent of differentiation. The most consistent finding for histological diagnosis was the presence of typical or abortive synapses with clear and dense-core vesicles. Additionally, synaptophysin may be a specific marker for some central neurocytomas.

Adult↗
PubMed1991

Chronic effects of methylmercury on the urinary excretion of catecholamines and their responses to hypoglycemic stress.

Five male Wistar rats were treated with methylmercury chloride (MMC) and compared with five age-matched control rats. A dose of 10 mg/kg was given three times. The chronic effects of the MMC administration on the urinary output of catecholamines [norepinephrine (NE), epinephrine (E) and dopamine (DA)] were measured for 50 days. On the 69th day after MMC administration, the rats were examined for insulin-induced hypoglycemic stress. On the 90th day, the animals were decapitated and various organs were weighed and serum thyroid hormones [thyroid stimulating hormone (TSH) and total and free thyroxine (T4)] were measured. Decreases in DA excretion and DA response to stress were observed in the MMC-treated group. Inflammation of the kidney was also found, suggesting MMC-induced damage to the renal tubular region, the apparent site of renal DA synthesis. The MMC group and the control group showed differential NE and E response patterns. The lowered baseline excretion of NE appeared to continue even 70 days after MMC administration, while the difference in E excretion between the two groups disappeared 1 month after MMC administration. Both NE and E showed normal responsiveness to hypoglycemic stress induced by insulin. All serum TSH and total and free T4 baseline levels showed slight increases, and the thyroid gland weights in the MMC group were slightly heavier. These findings suggest a rather hyperthyroid state after the initial acute phase suppression, as suggested by the previous examinations. Thus, these findings suggest long-lasting effects of methylmercury administration, especially on renal DA synthesis. Baseline urinary excretion of NE and thyroid function could also be affected for a long time.

Animals↗
PubMed1991

Reconstruction of the skull base using a silicone plate during transsphenoidal surgery.

Our operative experience of reconstruction of the skull base using a silicone plate during rhinoseptoplastic transsphenoidal surgery is described. A suitably shaped plate can be easily and quickly made from a large silicone block of the type that is widely used in cosmetic surgery. The plates can be distinguished on magnetic resonance images postoperatively. We consider that this technique is of use not only for repairing the sellar floor, but also for closing a wide defect of the skull base.

Adolescent↗
PubMed1991

Evaluation of extracranial-to-intracranial bypass surgery using iodine 123 iodoamphetamine single-photon emission computed tomography.

Eleven patients with occlusive cerebrovascular diseases were imaged with N-isopropyl-p-I-123 iodoamphetamine. Preoperative and postoperative single-photon emission computed tomography was performed in 10 patients undergoing extracranial-to-intracranial bypass procedures. New images were reconstructed from the two images obtained on the different days by superimposition and division in each pixel to get the ratio of cerebral perfusion change. All patients with bypass procedures had an increase in cerebral blood flow in the affected areas, and nine of 10 had an increase in cerebral blood flow in the contralateral cortex. There was no increase in cerebral blood flow in one case with no operation. Neither our procedure nor the results in this small series prove that recovery of function is due to an increase in blood flow, but we believe this is the case.

Adult↗
PubMed1991

Balloon occlusion of carotid-cavernous fistula via subtemporal transdural approach.

This is a report on a patient with traumatic carotid-cavernous sinus fistula (CCF). She gradually noticed noise in her head and suffered from partial ophthalmoplegia. Angiography demonstrated a left high flow CCF. She underwent a direct surgical treatment with a detachable balloon because an endovascular balloon embolisation for the CCF had been unsuccessful. Immediate disappearance of the bruits after surgery was noted and the patient recovered progressively her ophthalmoplegia. Follow angiograms 3 months after surgery revealed the disappearance of the fistula and an appearance of a false aneurysm. She is asymptomatic and periodically monitored in the outpatient clinic.

Arteriovenous Fistula↗
PubMed1991

EC-IC bypass for adult patients with moyamoya disease.

We have performed 10 bypass operations on 7 adult patients with moyamoya disease over the past 6 years. Four had haemorrhagic episodes and three had ischemic episodes. Three patients underwent superficial temporal artery-middle cerebral artery (STA-MCA) bypass on both sides and the other four had the procedure on one side. Six of 7 patients showed angiographical improvement after the bypass operation while one patient did not. This patient underwent the second severe stroke and became vegetative during the course of follow-up. Another patient died of myocardial infarction during the follow-up time. Five patients are capable of carrying out their original work. Considerations regarding the cause, operative methods and disease course in the patients are discussed.

Adult↗
PubMed1991

The correlation between immunological reaction in the arterial wall and the time course of the development of cerebral vasospasm in a primate model.

To investigate the role of immunological reactions in the development of cerebral vasospasm after subarachnoid hemorrhage (SAH), the authors studied the correlation between immune/inflammatory reactions in the arterial wall and the time course of vasospasm in primates. Twenty monkeys were divided into four groups of 5 animals each: 1) a control group of sham-operated animals, 2) animals subjected to angiography 3 days after the induction of SAH (3-day SAH), 3) animals subjected to angiography 7 days after SAH (1-week SAH), and 4) animals subjected to angiography 7 and 14 days after SAH (2-week SAH). To induce SAH, the main cerebral arteries on the right were dissected free of the arachnoid, and an autologous blood clot was placed around the arteries. To evaluate vasospasm, all animals underwent a baseline angiogram before SAH; angiography was repeated at different intervals in each group, as outlined above. Histopathological changes and the deposition of the immunoglobulin IgG in the arterial wall were evaluated immunohistochemically in each group. The cerebral arteries on the side of the clot showed evidence of mild vasospasm (-24.6% reduction) on the angiogram performed on Day 3, severe vasospasm (-51.7%) on Day 7, and mild vasospasm (-12.8%) on Day 14. The infiltration of inflammatory cells was most marked in the spastic arterial wall in the 1-week SAH group. In the 2-week SAH group, severe myonecrosis and intimal disruption were observed, even in the vessels that showed only mild vasospasm, and the inflammatory reactions had almost abated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Cerebral vasospasm and vasoconstriction caused by endothelin.

We investigated the histological changes between arteries constricted by endothelin for 7 days and vasospastic arteries induced by the double injection of autologous blood. Group 1 was a sham-operated group. Group 2 animals received a continuous cisternal injection of endothelin-1 (1.7 x 10(-9) mol/7 days) by a miniosmotic pump implanted in the neck musculature for 7 days. Group 3 received double injections of cisternal blood administered 48 hours apart. Angiography showed severe constriction of the basilar artery, 34.6% and 43% in Groups 2 and 3, respectively, on Day 7. Histological study showed marked constriction of the basilar artery in both Group 2 and Group 3. Degenerative changes in endothelial cells and smooth muscle cells were observed in both Group 2 and Group 3. Immunohistochemical study demonstrated endothelin-1 in the endothelial cells in Group 2, but not in Group 1 or in Group 3. It is suggested that endothelin-1 may play an important role in the pathogenesis of cerebral vasospasm.

Animals↗
PubMed1991

Changes in phosphorus-31 magnetic resonance spectra caused by epidural balloon in cats.

Changes in brain high energy phosphate metabolite and pH levels were studied using serial phosphorus (P)-31 magnetic resonance spectroscopy (MRS) in an epidural balloon cat model. The balloon was inflated with 1, 2, 3, or 4 ml of water at 1 ml/sec and deflated after obtaining a spectrum 4 minutes later. Serial spectra, intracranial pressure (ICP), physiological parameters, and the pupil sizes were observed for 1 hour. The mean ICP after balloon inflation increased to between 36 +/- 3 and 130 +/- 6 mmHg. Some animals showed oculomotor paralyses. Phosphocreatine, adenosine triphosphate, phosphodiester, and phosphomonoester levels suddenly decreased after inflation and gradually recovered after balloon deflation. Acidosis progressed with cerebral compression for 4 minutes and gradually recovered. All changes and recovery were volume related. This study demonstrates the potential of P-31 MRS for noninvasive, serial, in vivo measurements of critical high energy phosphate metabolites and intracellular pH after head injury.

Animals↗
PubMed1991

Effect of chemical sympathectomy on cerebral blood flow in rats.

Thirty male Wistar rats, weighing 350 to 400 gm each, received stereotactic injections of 6-hydroxydopamine (300 micrograms/kg) into the left lateral ventricle. The same amount of saline was injected into a control group of 15 rats. Seven days after this procedure, cerebral blood flow (CBF) was measured by the hydrogen clearance method. A hypertensive condition at a mean arterial pressure of about 160 mm Hg was maintained for 1 hour by intravenous infusion of phenylephrine. In the 6-hydroxydopamine-treated group, CBF increased significantly after the elevation of systemic blood pressure compared with that in the control group, and cerebral autoregulation was impaired. After a 1-hour study, the specific gravity of the cerebral tissue in the treated group significantly decreased; electron microscopic studies at that time revealed brain edema. It is suggested that depletion of brain noradrenaline levels causes a disturbance in cerebral microvascular tone and renders the cerebral blood vessels more vulnerable to hypertension.

Animals↗
PubMed1991

[Influence of total body hyperthermia on normal brain tissue].

The influence of total body hyperthermia (TBHT) on normal brain tissue was studied in 40 dogs. The dogs were anesthetized with sodium thiopental (10 mg/kg/hr) intravenously, and were ventilated by artificial respirator. The TBHT was induced by extracorporeal circuit in cooperating a heat exchanger. Rectal temperature was raised to 41.5 degrees C and maintained at 41. 5 -42.0 degrees C for 2 hr (HT period) and was then fallen to normothermia by cooling, Regional cerebral blood flow (CBF) was measured by hydrogen clearance method before heating, during and after TBHT treatment. Brain temperature, rectal temperature, intracranial pressure (ICP), brain tissue pH and electroencephalography (EEG) were monitored continuously during TBHT. Histopathological changes of the brain tissue were studied in dogs killed just after TBHT and 2 weeks after TBHT. Autoregulation of the CBF during HT period was assessed by measuring the regional CBF and the ICP at a state of induced hypo- or hypertension. The brain temperature (at the depth of 5mm under the brain surface) was usually 0.6 degrees C lower than the rectal temperature during HT period. The regional CBF increased from 38.1 +/- 6.5 (mean +/- SD) to 49.1 +/- 9.8ml/100 g/min by raising rectal temperature, and it recovered to a normal value after cooling. The ICP increased from 10.3 +/- 4.2 to 16.8 +/- 3.4 mmHg by raising rectal temperature, and it returned to a normal value after cooling. Brain tissue pH decreased from 7.33 +/- 0.02 to 7.17 +/- 0.09 rapidly when the rectal temperature reached 41.0 degrees C, and then returned to a normal value gradually after the start of cooling.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Effect of calcium channel antagonist (nicardipine) on growth hormone and prolactin secretion in pituitary adenomas].

This study was designed to investigate the effect of calcium channel antagonist (nicardipine) on basal and bromocriptine-inhibited GH or PRL secretion in eight patients with pituitary adenomas (six GH producing adenomas and two prolactinomas). GH or PRL was measured in blood collected at intervals for 12 hours after oral administration of nicardipine (Nc) (40 mg) and/or bromocriptine (Br) (2.5 mg) in each case. In vitro, pituitary adenoma cells were incubated in media containing Nc (200 ng/ml) and/or Br (200 ng/ml) over a 72-h period, and then in drugs-free media for three days. Media were collected at 24-h intervals and assayed for GH or PRL. In three of six GH producing pituitary adenomas, GH secretion was inhibited by Nc both in vivo and in vitro. In prolactinomas, PRL secretion was inhibited by Nc in vitro, but in vivo, an increase of plasma PRL levels was observed after Nc administration in one of two cases. In two acromegalic patients and one patient with prolactinoma, Nc reduced the suppression of GH or PRL secretion induced by Br. These findings indicate that influx of extracellular calcium plays an important part in both GH and PRL secretion in functioning pituitary adenomas, and that Nc effects on GH and PRL secretion in pituitary adenomas by blocking of influx of calcium and/or antidopaminergic action. It is considered that the combined administration of calcium channel antagonist (Nc) and Br for acromegalic patients and administration of Nc for patients with prolactinomas should be avoided.

Adenoma↗
PubMed1991

[Inventions for preservation of hormonal function in long-term culture of human functioning pituitary adenoma].

This study was designed to establish in vitro model systems in human hormone-producing pituitary adenomas that are analogous to the in vivo cellular environment. Mechanically dispersed cells composed of single cells and aggregates from 6 pituitary adenomas (3 GH producing adenomas and 3 prolactinomas) were cultured on microporous membrane cell culture inserts (Millicell-CM) coated with Basement Membrane Matrigel for up to 6 months. Growth hormone or prolactin in the medium was measured during the culture, and morphological feature in vitro was also compared with that of the original tumor at intervals. Not only single cells but also large aggregated cells which usually float in the medium when seeded on conventional plastic, were flattened and firmly attached to coated microporous membrane under the control of medium volume in culture. In both type adenomas, especially prolactinomas, surviving aggregated adenoma cells revealed preserved hormone activity and no dedifferentiation of cell characteristics after 6 months in culture. Particularly during the first 2 months in culture, close similarity existed between in vivo and in vitro conditions with regard to cell morphology and hormone release. These results indicate that this new culture method may further aid the investigation of in vitro cellular structure and function in human pituitary adenomas under conditions which closely mimic the in vivo cellular environment.

Adenoma↗
PubMed1991

Effect of cyclosporine on the development of cerebral vasospasm in a primate model.

The authors studied the effect of the immunosuppressive drug cyclosporine (CS) on the development of cerebral vasospasm after subarachnoid hemorrhage (SAH) using a primate model of vasospasm. Eighteen monkeys were randomly divided into three groups: a sham-operated control group, an SAH group, and a CS-treated group. To induce SAH, the right side of the circle of Willis was dissected free of the arachnoid and an autologous blood clot was placed around the arteries. In the CS group, CS (5 mg/kg/day) was administered intramuscularly for 7 days after the induction of SAH. The vessel caliber was evaluated on angiograms before the induction of SAH (Day 0) and 7 days after SAH (Day 7). Histological changes and the deposition of IgG in the arterial wall were studied in the three groups. The combined values of the average reduction of the right cerebral arteries at Day 7 was significant (P less than 0.05) in the SAH group (-43.3%) and in the CS group (-31.3%) as compared with the Sham group (-0.7%); however, there was no significant difference between the values in the SAH and the CS groups. In the CS group, the average reduction in vessel caliber of the right middle and anterior cerebral arteries was significantly (P less than 0.05) less than in the SAH group; this did not prove true for the internal carotid artery, however. Although the deposition of IgG in the media and an inflammatory reaction were observed in the spastic arterial wall in both the SAH and CS groups, there was no definitive difference in these immune/inflammatory reactions between the two groups. It is suggested that CS may be helpful in reducing the severity of vasospasm, but may not have a major therapeutic effect, considering its systemic toxicity.

Animals↗