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Biomedical subjects

K Shoin

Publications and source records attributed to K Shoin.

At least 19 recordsLinked to original sources
PubMed1999

Cranionavigator combining a high-speed drill and a navigation system for skull base surgery--technical note.

Drilling of the skull base bone without damaging the important inside structures and with the correct orientation is very difficult even with the help of the anatomical landmarks. Monitoring of the location and direction of the drill tip and indications of the removed part of the bone during the drilling procedure enhances safety and achieves less invasive neurosurgery. We have developed a novel cranionavigator by combining a high-speed drill with a neurosurgical navigation system. To reduce the positional error to less than 1.5 mm, the position sensor (magnetic field sensor) must be attached 5 cm from the metallic fan portion of the drill and the sensor kept at least 10 cm away from the operating microscope. Simulation studies with the cranionavigator using two dried skulls and three cadaver heads were performed before clinical application. Clinically, this surgical instrument was used in four patients with the skull base tumor. The cranionavigator helped to safely drill the skull base bone in a shorter time by dynamic and real-time display of the precise operating site and extent of bone drilling on the preoperative computed tomography scans or magnetic resonance images. The cranionavigator is a very helpful instrument for skull base surgery in the hands of neurosurgeons with extensive expertise and anatomical knowledge.

Craniotomy↗
PubMed1999

Postpartum dissecting aneurysm of the superior cerebellar artery--case report.

A 37-year-old female with toxemia of pregnancy suffered sudden headache and loss of consciousness on the day following a cesarean delivery. Computed tomography revealed subarachnoid hemorrhage (SAH). Vertebral angiography revealed a fusiform dilatation near the origin of the right superior cerebellar artery (SCA) with distal luminal narrowing. She underwent surgery within 24 hours of the ictus. A SAH clot was carefully removed from the prepontine cistern, and subadventitial discoloration was seen in the wall of the right SCA just distal to the aneurysmal protuberance (rupture site). The dissecting aneurysm was treated with body clipping by directly clipping the rupture site and with additional wrapping of the proximal SCA, including the aneurysmal protuberance and discolored site. The postoperative clinical course was uneventful. Postoperative angiography revealed complete obliteration of the aneurysm and patency of the SCA. Therapeutic intervention should be considered for patients with ruptured dissecting aneurysm who present with recurrent SAH.

Adult↗
PubMed1993

Effects of high-dose chemotherapy with syngeneic bone marrow transplantation in experimental brain tumor in rats.

BACKGROUND: The clinical dose of 3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-1-(2-chloroethyl)-1-nitro- sourea hydrochloride (ACNU) is limited by the bone marrow suppression it produces. The authors investigated whether bone marrow transplantation (BMT) associated with a high dose of ACNU could alleviate marrow toxicity and achieve greater antitumor effects in Fischer rats. METHODS AND RESULTS: High doses of ACNU (20, 25, and 30 mg/kg) were administered on day 1, followed by injection of syngeneic bone marrow cells on day 3. Patterns of leukocyte recovery were compared in BMT and non-BMT groups. There was a significant benefit in leukocyte recovery in the BMT groups. A 9L glioma that was sensitive to ACNU was transplanted into the brain tissue of rats. Seven days later, the animals were divided into three groups based on the dose of ACNU (2, 10, and 25 mg/kg). The median survival time increased with larger ACNU doses. CONCLUSIONS: This suggested that high-dose ACNU chemotherapy with BMT could achieve greater antitumor effects and less bone marrow suppression than high-dose ACNU alone.

Animals↗
PubMed1991

Chick embryo assay as chemosensitivity test for malignant glioma.

To predict the efficacy of anticancer drugs such as ACNU [1-(4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl-3-nitrosoure a hydrochloride] and MCNU [1-(2-chloroethyl)-3-(methyl-alpha-D-glucopyranos-6-yl)-1-nitrosou rea] in the treatment of malignant gliomas, the usefulness of the chick embryo assay as a chemosensitivity test was studied. Fifty-seven surgical specimens including benign tumors were examined by this method. All tumor specimens tested could be grafted on the chorioallantoic membrane of chick embryo; the evaluable ratio was 100%. Twenty-one patients with previously untreated malignant glioma could be evaluated to test the predictability of the clinical effects, judged by computed tomography. There were 7 (78%) instances in which the assay response corresponded to a clinical partial response (true-positive). There were 2 (22%) false-positives for the assay, 0 (0%) false-negative and 12 (100%) true-negatives. The over-all predictive accuracy was 90% (19/21). Thus, a high-degree of positive association exists between the chick embryo assay and the clinical outcome. This in vivo assay system for malignant glioma is advantageous for chemosensitivity tests because of its convenience, rapidity, and inexpensiveness.

Allantois↗
PubMed1990

Neurotoxicity of local administration of two nitrosoureas in malignant gliomas.

The neurotoxicity of local administration of nitrosoureas in malignant gliomas was investigated clinicopathologically. Twenty patients were entered into this study: 13 were treated with 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU) and 7 with methyl 6-[3-(2-chloroethyl-3-nitrosoureido]-6-deoxy-alpha-D-glucopyranoside (MCNU). On the average, a single dose of 20 mg of ACNU was administered 15 times, for a total dose of 295 mg in each case, while a single dose of 11 mg of MCNU was given 2 times, for a total dose of 24 mg. These nitrosoureas provoked greater toxicity when the administration dose was larger or the indwelling multiperforated Silastic basket was in direct continuity with the ventricle or the basal cistern. Usually ACNU was well tolerated, whereas MCNU induced marked brain edema. Side effects consisted of headache, nuchal stiffness, vomiting, motor weakness, and cranial nerve palsy for ACNU, and headache, vomiting, abnormal respiration, and arrhythmia for MCNU. Pathological changes were represented by capsule formation, spongy degeneration and reactive gliosis of adjacent white matter, occlusion of neighboring arteries, and demyelination of cranial nerves in the patients treated with ACNU, while they were represented by focal brain necrosis in two patients treated with MCNU. The differences in neurotoxity of ACNU and MCNU conceivably derive from the different blood-brain delivery of these drugs.

Adolescent↗
PubMed1989

Granuloma caused by oxidized cellulose following craniotomy.

Three cases are reported in which large granulomas developed 13 to 21 months respectively after removal of intracranial meningiomas (2 cases) and after operation for an anterior communicating artery aneurysm. In each of the cases oxidized cellulose had been used and left in place for haemostasis. All of the granulomas acted as space-occupying lesions. They could be removed operatively with good result. All of them consisted of mononuclear phagocytic and multi-nuclear giant cells and contained remnants of oxidized cellulose. No comparable cases have been reported in the literature. Diagnosis, treatment and possible aetiological factors are discussed.

Adult↗
PubMed1987

Preoperative diagnosis of Rathke's cleft cyst.

Two cases of Rathke's cleft cyst are presented. The cysts showed as high-density lesions on plain CT with slight enhancement with contrast medium. They appeared as a hyperintense mass in the T 1-weighted magnetic resonance images. Preoperative diagnosis is very important because different sellar cystic lesions require different treatment.

Adolescent↗
PubMed1987

The change of plasma volume, central venous pressure and water balance of patients treated by haemodynamic therapy for vasospasm.

The plasma volume, central venous pressure and water balance of 24 patients were measured around the 1st and 2nd week after early operations for ruptured aneurysms. All of the patients had been successfully treated by induced hypertension therapy for delayed vasospasm. Plasma volume was measured by the RI method using RISA. The average plasma volume of 16 patients was 58.3 +/- 6.2 ml/kg. This group had 200 ml of 25% albumin every day. It was 48.2 +/- 6.2 ml/kg for 8 patients without albumin administration. The average CVP was 11.3 +/- 2.2 cm on the albumin group. It was 5.3 +/- 1.5 cm on the non-albumin group. The value of plasma volume and CVP was statistically higher in the albumin group than in the non-albumin group. Water balance was positive in about half of the albumin group. It was negative in the non-albumin group. Three patients of the albumin group had pulmonary oedemas and one patient of the non-albumin group had congestive heart failure.

Adult↗
PubMed1987

[Traumatic arteriovenous fistula with feeders of the scalp, dura mater and pia mater: case report].

A very rare case of 41-year-old male with symptomatic dural arteriovenous fistula which was detected after 22 years from receiving head injury is reported. This AVF had arterial blood supply of scalp, dural and pial origins. In the literature, only two similar cases have so far been reported. The draining veins were the superior sagittal sinus and the vein of Trolard, and a large vascular sac was seen in the pial vein.

Adult↗
PubMed1986

Meningeal hemangiopericytoma.

If meningeal hemangiopericytoma could be diagnosed prior to operation, the neurosurgeon might be better prepared to deal with excessive bleeding during the operation. This type of tumor should be completely excised because of the high risk of recurrence and remote metastasis. Computed tomography as well as cerebral angiography would aid in the preoperative diagnosis of hemangiopericytoma. Early detection and periodic observation by computed tomography may minimize the morbidity and mortality associated with late detection.

Adult↗
PubMed1986

Ascending fibers from the gigantocellular nucleus to the centromedian nucleus of the thalamus in cats.

Centrum medianum (CM) afferent pathways, which are involved in pain sensation, were analyzed using physiological techniques. Thirty-four neurons in the gigantocellular nucleus (nucleus gigantocellularis medullae oblongatae, GC) in cats were recorded intracellularly. Of these, 5 (15%) did not respond to electrical stimulation applied to any of the 4 limbs. Twenty-nine (85%) showed spike potentials that were superimposed on excitatory post-synaptic potentials (EPSPs) with an amplitude of 7.2 mV (n = 101) and a duration of 6.8 ms. The latencies from contra- and ipsilateral forelimb, contra- and ipsilateral hindlimb to the GC were 9.3 (n = 25), 7.2 (n = 23), 12.9 (n = 28), and 10.9 ms (n = 25), respectively. Of these responding neurons, 19 (66%) responded to stimuli to all 4 limbs, 7 (24%) to 3 limbs, 1 (3%) to 2 limbs, and 2 (7%) to 1 limb. These afferent neurons in the GC showed spike potentials without EPSPs after stimulation of the CM in the thalamus. Extracellular activities of 37 CM neurons were also tested. Of these, 4 neurons responded to GC stimulation with a short latency of 1.6 ms. Another 33 responded with a long latency of 6.7, and 11 of them were able to follow GC stimulation of over 200 Hz with a fixed long latency; 22 responded with varying long latencies but were not able to follow stimuli over 15 Hz. Three-quarters of the CM neurons received ipsilateral inputs from the GC, and the other contralateral inputs. Three CM neurons responded to stimulation of the GC in quasi-intracellular records. These findings suggest that some ascending fibers from the GC terminate on CM neurons and play a role in pain sensation.

Animals↗
PubMed1986

[Change of plasma volume on patients treated by induced hypertension therapy for vasospasm].

UNLABELLED: Plasma volume, central venous pressure and water balance of 24 patients were measured about 1st and 2nd week after early operation for the ruptured aneurysms. All of the patients had been treated by induced hypertension therapy for delayed vasospasm successfully. Plasma volume was measured by RI method using RISA. The average of plasma volume of 16 patients was 58.3 +/- 6.0 ml/kg. This group had 200 ml of 25% albumin every day. It was 48.2 +/- 6.2 ml/kg on 8 patients without albumin. The average of CVP was 11.3 +/- 2.2 cm on the albumin group. It was 5.3 +/- 1.5 cm on the other group. The value of plasma volume and CVP was higher statistically on the albumin group than the other group. Water balance was positive on about half of the albumin group. It was negative on the other group. Three patients of the albumin group had pulmonary edema. THE CONCLUSION: The state of patient's hydration is not hypovolemic, as far as the induced hypertension therapy is possible, even though patient's CVP is low and water blance is negative. Albumin lets the plasma volume increase easily. Therefore, the risk of pulmonary edema may rise when only unreliable CVP is used for the monitoring of plasma volume. Plasma volume measurement is indispensable to the monitoring of fluid management for vasospasm and plasma volume should be aimed at 55-60 ml/kg.

Adult↗