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Biomedical subjects

K Hongo

Publications and source records attributed to K Hongo.

123 records · Page 7Linked to original sources
PubMed1988

Metabolic alterations in rabbit cerebral arteries caused by subarachnoid hemorrhage.

The effect of subarachnoid hemorrhage on metabolic rates in rabbit cerebral arteries was investigated by measuring adenosine triphosphate (ATP) content and L-lactate release. The mean +/- SEM ATP content was 0.38 +/- 0.02 mumol/g wet wt in control rabbit basilar arteries (n = 6). The ATP content decreased significantly to 0.17 +/- 0.02 mumol/g wet wt 2 days after experimental subarachnoid hemorrhage (n = 6), although only a slight decrease was detected in the basilar arteries 2 days after cisternal injection of the same amount of artificial cerebrospinal fluid. Hypoxia significantly decreased ATP content in the control basilar arteries to 0.26 +/- 0.04 mumol/g wet wt (n = 6). The same degree of hypoxia did not decrease ATP content in the basilar arteries after subarachnoid hemorrhage. Release of L-lactate was significantly higher from the arteries after subarachnoid hemorrhage than from the control arteries under both aerobic and hypoxic conditions. Our results indicate that subarachnoid hemorrhage induced an alteration of metabolic rates in rabbit cerebral arteries. The oxygen-requiring pathways to synthesize ATP may be important in control cerebral arteries; however, after experimental subarachnoid hemorrhage, the main pathway in the cerebral arteries may shift from oxygen-requiring pathways to an anaerobic glycolytic pathway.

Adenosine Triphosphate↗
PubMed1988

Effects of aging and hypertension on endothelium-dependent vascular relaxation in rat carotid artery.

We evaluated the effects of aging and hypertension on endothelium-dependent relaxation of rat common carotid arteries using 14-week-old (young) and 11-month-old (old) Wistar-Kyoto rats (WKY) and age-matched spontaneously hypertensive rats (SHR). Isometric tension of common carotid artery ring segments was measured. With a resting tension of 2.0 g determined from the baseline tension-contraction curves, precontraction was induced by 10(-5) M 5-hydroxytryptamine and endothelium-dependent relaxation was measured by application of either acetylcholine or adenosine 5'-triphosphate (ATP). Mean arterial blood pressure was 73.1 +/- 3.0 mm Hg in WKY and 110.0 +/- 3.1 mm Hg in SHR. These baseline values were significantly different. Acetylcholine-induced maximal relaxations were 70.1 +/- 2.6% of the 5-hydroxytryptamine-induced contraction in young WKY, 45.6 +/- 2.1% in old WKY, 35.1 +/- 1.8% in young SHR, and 21.4 +/- 2.5% in old SHR. On the other hand, ATP-induced relaxations were 52.0 +/- 3.2%, 35.7 +/- 3.8%, 21.7 +/- 3.5%, and 17.0 +/- 1.8% in the groups, respectively. Acetylcholine-induced relaxations were significantly different between WKY and SHR, young and old, independently. On the other hand, ATP-induced relaxations were also significantly different between young and old WKY, although no significant difference was observed between young and old SHR. The fact that endothelium-dependent relaxation of a cephalic artery is impaired in old rats and in hypertensive rats suggests that aging and hypertension are risk factors that may augment the disturbance of the cerebral circulation in pathologic conditions.

Acetylcholine↗
PubMed1988

Effect of removal of the endothelium on vasocontraction in canine and rabbit basilar arteries.

The effect of endothelium removal on the contractile responses to KCl, hemoglobin, serotonin (5-HT), norepinephrine (NE), prostaglandin (PG)F2 alpha, PGD2, and PGE2 was investigated in canine and rabbit basilar arteries by an isometric tension-recording method. In canine basilar arteries, endothelium removal elevated the dose-response curves to 5-HT, PGF2 alpha, and PGD2, and PGE2, but not to KCl, hemoglobin, or NE. In rabbit basilar arteries, on the other hand, removal of the endothelium elevated the dose-response curves to 5-HT, NE, PGF2 alpha, and PGD2, but not to KCl or hemoglobin. Neither contractile nor inhibitory response was elicited by PGE2 in rabbit basilar arteries. Contraction induced by 5-HT and NE following endothelium removal had a much more pronounced effect in rabbit basilar arteries than in canine basilar arteries. These results suggest that, following endothelium removal, abolition of the spontaneous release of endothelium-derived relaxing factor is the most probable mechanism of the enhanced vasocontraction. Since endothelial damage results from subarachnoid hemorrhage, the aforementioned mechanism of vasocontraction enhancement may play a role in the pathogenesis of cerebral vasospasm.

Animals↗
PubMed1988

Subarachnoid hemorrhage inhibition of endothelium-derived relaxing factor in rabbit basilar artery.

Vascular contractions in response to KCl and serotonin (5-hydroxytryptamine, 5-HT) in rabbit basilar artery were studied in vitro using an isometric tension-measurement technique. Hemoglobin (10(-5)M) markedly augmented contractions induced by 5-HT (10(-9) to 10(-6)M) and slightly augmented those induced by KCl (20 to 80 mM) in arteries with intact endothelium. On the other hand, the augmentation induced by hemoglobin was almost abolished in arteries that were chemically denuded of endothelial cells by pretreatment with saponin. Since hemoglobin is known to be a selective inhibitor of endothelium-derived relaxing factor (EDRF), it is possible that the augmentation of contraction by hemoglobin in endothelium-intact arteries was mediated via an inhibition of spontaneously released EDRF. The effect of subarachnoid hemorrhage (SAH) on spontaneously released EDRF was investigated by injecting 5 ml of blood into the cisterna magna and sacrificing the rabbits 2 days later. Arteries after SAH showed a significant reduction in hemoglobin-induced augmentation compared to that seen in control arteries with intact endothelium. This result suggests that spontaneously released EDRF is significantly reduced after SAH. It is concluded that EDRF is released spontaneously in the rabbit basilar artery and that inhibition of its release might be involved in pathogenesis of cerebral vasospasm.

Acetylcholine↗
PubMed1988

Pharmacological comparison of endothelium-dependent relaxation in isolated cerebral and extracerebral arteries.

Endothelium-dependent relaxation was induced by acetylcholine (ACh), adenosine triphosphate (ATP), and thrombin in isolated cerebral and extracerebral arteries obtained from rabbits and dogs. Using an isometric tension-recording method, the authors then examined the difference in the extent of relaxation between the cerebral and extracerebral arteries. In rabbits, the dose-response curve of the basilar artery for ACh was significantly different (p less than 0.05) from curves of the femoral and common carotid arteries. The IC50 value (the concentration inducing a one-half inhibition of the initial contractile tone) for the basilar artery in ACh-induced relaxation was significantly higher (p less than 0.05) than for the common carotid artery, although the mean maximum relaxation of the basilar artery to ACh was not significantly different from that seen in extracerebral arteries. The relaxing effect of ACh in dogs was much less in the middle cerebral and basilar arteries than in the common carotid, vertebral, and femoral arteries. On the other hand, both ATP (in rabbits and dogs) and thrombin (in dogs) induced significantly more (p less than 0.05) relaxation in the cerebral arteries than in the extracerebral arteries. Endothelium-dependent relaxation induced by ACh or ATP has been demonstrated in a wide range of arteries from a variety of animals. The present results suggest that ATP has a more important role than ACh in the regulation of the vascular tone of the major cerebral arteries in these two species.

Acetylcholine↗
PubMed1987

Immunohistochemical demonstration of increase in prostaglandin F2-alpha after recirculation in global ischemic rat brains.

Immunohistochemical localization of prostaglandin F2 alpha (PG F2 alpha) was studied in 24 rats. In 21 rats, global brain ischemia was produced for 5 min by Pulsinelli's method. Prior to decapitation, 13 were recirculated for 5 min, while the remaining eight were not. Three recirculated rats were pretreated with indomethacin before the occlusion. Hypotension was induced during the occlusion to 40-50 mm Hg of mean arterial blood pressure in 11 rats including those unrecirculated, recirculated and pretreated with indomethacin. Three normal rats without occlusion of arteries served as control. The brains were snap frozen and 10-microns cryostat sections were incubated in rabbit anti-PG F2 alpha serum and stained by the indirect immunofluorescence method after fixation in carbodiimide and in Zamboni's solution. Positive staining for PG F2 alpha was noted mainly in pial vessels in normal and ischemic rats both with and without hypotension. The rats recirculated without hypotensive ischemia revealed a positive reaction in the walls of pial and parenchymal vessels. All rats recirculated after the hypotensive occlusion showed positive staining in blood vessels, in the cytoplasm of neurons (especially in hippocampi) and in the interfascicular oligodendrocytes. The above results indicate that recirculation after ischemia results in an increase in PG F2 alpha in parenchymal vessels, neurons and oligodendrocytes.

Animals↗
PubMed1987

Monitoring retraction pressure on the brain. An experimental and clinical study.

The problem of minimizing tissue damage during brain retraction was studied both experimentally in dogs and clinically with the aid of newly designed strain-gauge retractor. The pressure required to obtain a specific exposure decreased gradually with time. The average time for a 50% reduction in retraction pressure was 6.6 minutes in the earlier trials of repeated retraction. The attenuation rate of retraction pressure gradually decreased when retraction of the same area was repeated. The lower the head position of the dog, the larger was the amplitude of brain retraction pressure. Clinical studies demonstrated that: 1) cerebrospinal fluid drainage was effective in decreasing the retraction pressure required; 2) use of multiple retractors reduced the pressure applied by each retractor; and 3) retraction pressure could be monitored when the strain-gauge retractors were applied to arteries and cranial nerves.

Adolescent↗
PubMed1985

Chronic meningitis with marked unilateral tentorial pachymeningitis.

Two cases of chronic meningitis with marked granulomatous thickening of the cerebellar tentorium are presented. The clinical features of both cases were those of chronic meningitis, namely, incessant chronic headache, long-lasting moderate increase of intracranial pressure, multiple cranial nerve involvement, slight lymphocytosis, and increased protein in cerebrospinal fluid. The characteristic finding on computed tomography scan was slight, high density of the unilateral cerebellar tentorium with marked contrast enhancement. Both patients died of complications, and necropsy revealed marked granulomatous thickening of the unilateral cerebellar tentorium. Although noninfectious disease was strongly suspected, the etiology could not be specified either clinically or by necropsy.

Adult↗
PubMed1985

Straight sinus meningioma.

Successful removal of a meningioma arising from the straight sinus is described. The tumor was removed via a combined right occipital craniotomy and suboccipital craniectomy. The occluded straight sinus and an unusual vein draining the Galenic system to the superior sagittal sinus were demonstrated angiographically. Various kinds of visual symptoms appeared after the operation, but these gradually cleared.

Adult↗
PubMed1985

[Posterior fossa microvascular decompression for hemifacial spasm and trigeminal neuralgia--some improvements on operative devices and technique].

Microvascular decompression has been widely used as a method for the treatment of hemifacial spasm and trigeminal neuralgia. We have experienced 30 such cases in the last 2 years; 25 of them were hemifacial spasm and 5 trigeminal neuralgia. Excellent results were obtained in 26 cases; the remaining two cases, both hemifacial spasm, were partially cured. Mild facial paresis appeared several days after the operation in 3 patients. In all the cases, the facial paresis recovered completely within several weeks. The cause of the facial paresis was not known. In 2 cases a slight hearing deficits were noticed after surgery, which has been gradually improving over several months. As this operation is functional surgery, operative complications must be avoided as much as possible. It has been our policy that we first try medical treatment and/or some kinds of nerve block and if no effects are obtained, we recommend the microvascular decompression. For microvascular decompression, suboccipital craniectomy is performed in lateral position. From the point of view of surgical technique, we stress several important points as follows: The head is elevated about 30 degrees, and it is kept approximately horizontal and should not be excessively rotated. Craniectomy is made as far laterally as the sigmoid sinus; its shape is elongated oval. Retraction of the cerebellum should not be done in the direction of the cranial nerves to avoid post-operative hearing deficit. Two tapered retractors are effectively used for cerebellar retraction. A third slim, tapered retractor is useful for holding an offending artery when exploring the root exit zone or placing a sponge for decompression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

A new method for measuring vascular responsiveness of relatively larger arteries of dogs.

A new model of isolated vascular preparation was developed in the dog. Several canine arteries were isolated and suspended in a bath and perfused under a constant flow rate with Ringer-Locke solution. In each experiment, resting perfusion pressure was set at a constant level at 40-60 mm Hg. Drugs were administered in the endothelial side of the artery through a cannulated tubing, and the response was obtained as changes in the perfusion pressure. By inserting the polyethylene cannula into the artery, the space between the luminar wall of the artery and the cannula was decreased enough to obtain a suitable perfusion pressure, while the cannula was filled with the fluid by pumping. Although some other methods have been used to observe contractile responses of the artery, this method might be superior to them because: 1) drugs act only on the luminar wall; 2) vascular responses to drugs, not only constriction, but also dilatation, in nontreated preparations, are readily observed in a relatively larger artery (2-3 mm I.D.); 3) the vascular reactivity is kept in a stable condition over 7-8 hours at 37 degrees C. We used this preparation to examine the contractile responses of the common, internal, external carotid, and femoral arteries to 5-hydroxytryptamine.

Adenosine↗
PubMed1982

Polymorphonuclear leukocyte chemotaxis in sporotrichosis.

A lesion of sporotrichosis shows a characteristic arrangement of the infiltrate in three zones: the central suppurative zone composed of polymorphonuclear leukocytes, the tuberculoid zone and the round cell zone. For investigating the pathomechanism of the suppurative zone formation, polymorphonuclear leukocyte chemotaxis to sporotrichin was assayed with the agarose plate method. Polymorphonuclear leukocytes in the patients with sporotrichosis showed an enhanced chemotactic index in comparison with that in the control subjects. However, there was no difference in non-specific chemotaxis to bacteria-derived substance between the patients and the control subjects.

Aged↗
PubMedDate not supplied

Endodermal cyst in the cerebellopontine angle with immunohistochemical reactivity for CA19-9.

We present a rare case of the endodermal cyst in the cerebellopontine angle with positive immunohistochemical reactivity for CA19-9. The patient was a 67-year-old woman with an endodermal cyst in the cerebellopontine angle who presented with progressive gait disturbance. A magnetic resonance image showed a cerebellopontine angle which was low in signal on T1-weighted, and high on T2-weighted image without gadolinium enhancement. The preoperative diagnosis was an epidermoid or arachnoid cyst. The patient underwent surgery. Since the intraoperative histological diagnosis by frozen section was endodermal cyst, total removal of the cyst wall was achieved for preventing recurrence. The postoperative definitive histological diagnosis was endodermal cyst, type A by Wilkins-Odom classification, lined by mucinous epithelium with an immunohistochemical reactivity for CA 19-9 protein and cytokeratin. This is the first reported case of a huge endodermal cyst in the cerebellopontine angle of an elderly woman which exclusively showed a differentiation toward the midgut epithelium. The histological diagnosis during surgery by frozen section should be performed for proper treatment.

Aged↗