Biomedical subjects

M Komiyama

Publications and source records attributed to M Komiyama.

At least 109 records · Page 6Linked to original sources

PubMed1997

Spontaneous spinal subarachnoid hematoma of unknown pathogenesis: case reports.

OBJECTIVE AND IMPORTANCE: The occurrence of spontaneous spinal subarachnoid hematoma of unknown pathogenesis is extremely rare. In the cases reported to date, the hematoma, located dorsal to the spinal cord (dorsal type), has caused paraplegia and has required emergency surgical intervention. CLINICAL PRESENTATION: We examined two patients who sustained spontaneous spinal subarachnoid hematoma. Both experienced sudden back pain, but there were no symptoms of spinal cord compression. Magnetic resonance imaging revealed spinal subarachnoid hematoma located ventral to the spinal cord (ventral type). INTERVENTION: Both patients were treated conservatively, and follow-up examinations have revealed that they have remained neurologically normal for 7 years and 6 months, respectively. CONCLUSION: We postulate that there are two types of spontaneous spinal subarachnoid hematoma of unknown pathogenesis (ventral and dorsal types), each of which presents a distinct clinical picture and prognosis. Ventral type hematoma may be one of the causes of acute back pain, and because of its benign prognosis, surgical treatment may not be necessary.

Adult↗

PubMed1997

Choroidal detachment and dural carotid-cavernous sinus fistula--case report.

A 71-year-old female presented with the rare complication of choroidal detachment after endovascular treatment of a dural carotid-cavernous sinus fistula. Since the residual arteriovenous shunt flow was minimal and intraocular pressure was normal, the choroidal detachment was treated conservatively and disappeared within one month. The possibility of choroidal detachment during the clinical course of a dural carotid-cavernous sinus fistula should be recognized.

Aged↗

PubMed1997

[Intraoperative aneurysmal rupture at the neck].

Intraoperative rupture of an aneurysm can lead to disastrous results when the rupture occurs at the neck. The authors have encountered eight cases (5%) of intraoperative rupture in a series of 155 patients. All patients were operated on in the acute stage by one of the authors of this paper (T.Y.). In six cases, the aneurysm ruptured at the dome and in two, at the neck. We report these two patients with intraoperative rupture at the neck. The first case, a 50-year-old female, developed SAH, but a 4-vessel study failed to show an aneurysm. The second series of angiograms obtained ten days later showed a broad-based, left proximal A1 aneurysm. It was decided to employ a right pterional approach. The aneurysm was arising from the right A1 segment just proximal to the anterior communicating artery. The neck was wide, with thin walls. Thus, it seemed better to apply a clip parallel to the A1 segment axis than to apply it from a direction perpendicular to the A1 segment axis. However, the right pterional approach precluded a parallel clipping, so the blades of a clip were applied perpendicularly. The clip seemed not to be completely across the neck of the aneurysm. After applying a temporary clip to the A1 segment proximal to the aneurysm, the clip blades were opened and advanced just when bursting of the sac at the base occurred and microvascular suture repair was required to control the bleeding. The second case, a 57-year-old female, underwent clipping of a right IC-PC aneurysm. However, two years postoperatively, the patient again suffered SAH. Cerebral angiography at this time revealed a relatively large recurrent IC-PC aneurysm in which the old clip was situated on the dome of the aneurysm. Aneurysmal clipping was performed on the day of rupture. Tough granular tissue was removed from the ICA, PcomA, aneurysmal neck, and the old clip. After the true neck was identified, a straight clip was applied to the neck parallel to the ICA. Soon after the clipping, arterial bleeding occurred near the neck. The ruptured aneurysm was trapped using two temporary clips. A curved clip was applied to the ruptured neck, including the wall of the ICA, to control the bleeding. This clipping caused a substantial stenosis of the ICA. Both patients demonstrated postoperative neurological deficits due to ischemia caused by temporary clipping. These encounters dramatically demonstrated that a very thin-walled aneurysm or a recurrent aneurysm has a fragile neck. In surgical treatment of these unusual aneurysms, a clip should be placed on the neck parallel to the parent artery. Furthermore, temporary clipping is advisable when dissecting the neck or applying the clip to the neck to reduce the damage to the neck.

Aneurysm, Ruptured↗

PubMed1997

The accessory middle cerebral artery as a collateral blood supply.

We describe two cases of acute embolic occlusion of the internal carotid artery and the middle cerebral artery in association with a patent accessory middle cerebral artery. Because of the presence of the accessory middle cerebral artery, the frontal lobe was salvaged to some extent, but it did not provide sufficient collateral blood supply to the middle cerebral artery territory to spare the rest of the frontal lobe, the temporal lobe, and the basal ganglia.

Aged↗

PubMed1997

[Rupture of previously documented asymptomatic saccular intracranial aneurysms].

The authors report four cases of patients with documented asymptomatic intact aneurysms that subsequently ruptured. Case 1 involves a 64-year-old woman who had two unruptured aneurysms, i.e., an anterior communicating artery aneurysm and a posterior inferior cerebellar aneurysm, both were discovered during evaluation of cerebral ischemic symptoms. At that time, only the posterior inferior cerebellar aneurysm was clipped. Seven years later, the patient bled fatally from a 5-mm untreated anterior communicating artery aneurysm that had measured approximately 3 mm on an angiogram obtained 7 years earlier. Case 2 is that of a 50-year-old woman who bled from an anterior communicating artery aneurysm that had been discovered 6 years earlier when she suffered subarachnoid hemorrhage (SAH) from a left middle cerebral artery aneurysm. At that time, she had refused surgery for the anterior communicating artery aneurysm. She recovered well from the second SAH. Case 3 is that of a 74-year-old woman who bled from a left paraclinoid internal carotid artery aneurysm that had been discovered incidentally 3 years earlier during evaluation of vertigo. She had not agreed to have a clipping at that time the aneurysm was first discovered because of her age and the difficult location of the aneurysm. She eventually made an uneventful recovery. In the fourth case, during evaluation of cerebral ischemic symptoms, a 59-year-old man was discovered to have a large basilar bifurcation aneurysm. He underwent a craniotomy for clipping of the aneurysm. The aneurysm, however, was unclippable and was instead coated with Bemsheet. Four months later, the patient bled from the aneurysm and entered a vegetative state. The indications for surgery on unruptured asymptomatic cerebral aneurysms are still unclear. The cases reported herein show that asymptomatic aneurysms, especially anterior communicating aneurysms and aneurysms once exposed surgically, do carry a certain risk for future hemorrhage and should not be dismissed as innocuous. Neurosurgeons have recognized the importance of considering life expectancy in managing patients with asymptomatic, unruptured, intracranial aneurysms. With the rapid aging of the population, withholding aneurysm surgery merely because a patient is elderly may not necessarily be the most appropriate decision.

Aged↗

PubMed1997

[Management of subarachnoid hemorrhages without detectable aneurysm].

In this study, 21 patients with subarachnoid hemorrhage (SAH) but negative angiography were evaluated. Angiography was performed twice on each patient, that is, on admission and at 2 weeks following admission. All patients had severe headache of sudden onset, a characteristic manifestation of SAH. Clinical grades on admission (Hunt and Kosnik classification) were generally good: 17 patients were in grade I or II and 4 patients were in grade III. SAH was confirmed by the presence of subarachnoid clot on CT in all cases. Based on the distribution of SAH, CT findings were classified into two patterns, i.e., perimesencephalic and non-perimesencephalic patterns. Four patients showed the perimesencephalic pattern and the remaining 17 the non-perimesencephalic. The period of follow-up ranged from 20 days to 11 years 6 months, with a mean of 6 years 10 months. Except for three recent cases, the mean follow-up period in 8 years 9 months. Exploratory craniotomies probing for aneurysms have been performed in four patients, but no aneurysms have been found in any of these cases. Clinical deterioration associated with vasospasm was observed in one patient. A communicating hydrocephalus requiring a shunting procedure was observed in three patients showing the non-perimesencephalic type CT pattern. Rebleeding occurred in one patient who subsequently died of what may be a dissecting aneurysm of the vertebral artery. One patient who was able to return to full activity experienced symptoms attributable to SAH such as frequent headaches and increased fatigability. Complete recovery was observed in the remaining 19 patients. Two of them, however, later died due to myocardial infarction and aging, respectively. Given these generally positive outcomes, it should be possible to inform such patients of the benignity of their condition. Angiography may not demonstrate a ruptured aneurysm on initial examination in all cases of aneurysmal SAH. Serial angiography, however, can provide a definite diagnosis of the dissecting aneurysm. Therefore, repeat angiography, particularly, when possible, digital subtraction angiography, is necessary to rule out aneurysmal SAH. While small aneurysms or microaneurysms are often found through exploratory craniotomy, we do not agree with the opinion that surgery may be appropriate for certain patients with SAH but with negative angiography. The natural history concerning rebleeding in such cases, as well as morbidity and mortality associated with hemorrhage, remains to be defined. Furthermore, there are reservations regarding whether coagulation of these abnormalities with bipolar cautery constitutes definitive treatment.

Adult↗

PubMed1997

Reversible pontine ischemia caused by acetazolamide challenge.

We report the findings in a patient with a midbasilar artery stenosis in whom reversible ischemic neurologic deficits developed during cerebral blood flow imaging with acetazolamide challenge. The potential for ischemic complications from acetazolamide challenge is discussed.

Acetazolamide↗

PubMed1997

Direct extracranial-intracranial bypass for children with moyamoya disease.

To improve cerebral hypoperfusion in the ischemic type of Moyamoya disease, we have applied superficial temporal artery-middle cerebral artery (STA-MCA) double anastomoses in combination with encephalo-myo-synangiosis (EMS) for 19 hemispheres of 10 children (age from 5 to 11 years at surgery). Two branches of the STA were anastomosed to the two cortical arteries which were selected in the watershed area of the cerebral hemisphere estimated as a hypoperfusion area on the preoperative angiograms. Before surgery transient ischemic attacks (TIAs) developed from every month to every 6 months in association with hyperventilation or sobbing. No perioperative completed stroke or wound complications was observed, although single TIA developed in four patients within 1 month after surgery. Postoperative angiogram demonstrated that, not only the preoperative watershed area, but also the most of the middle cerebral artery territory was oppacified via the 2 branches of the STA in all 19 hemispheres. In a mean follow-up period of 4 years, no ischemic episode was induced by hyperventilation, and there was no mental or neurological deterioration. STA-MCA double anastomoses, to the cerebral watershed area, in combination with EMS are safe and effective even for younger children with Moyamoya disease.

Anastomosis, Surgical↗

PubMed1997

Sequence-selective RNA scission by oligoamine--DNA conjugates (1).

Ethylenediamine and diethylenetriamine, which are active for RNA hydrolysis, are attached to the 5'-ends of synthetic oligonucleotides by urethane linkages. The resultant artificial ribonucleases selectively hydrolyze the substrate RNA at the target phosphodiester linkage. Acid/base cooperation in the oligoamines for the catalysis is confirmed in terms of kinetic evidences.

Base Sequence↗

PubMed1997

Homogeneous catalyst for DNA hydrolysis (4). Efficient DNA hydrolysis by lanthanide--saccharide complexes.

Homogeneous and neutral solutions are prepared by mixing Ce(NH4)2(NO3)6 with either isomaltose, melibiose, gentiobiose, palatinose, mannitol, sorbitol, galactitol, or glucamine in pH 7 hepes buffer ([Ce(IV)]0/[monomeric residue of saccharide]0 = 1). In contrast, amylose, cyclodextrins, maltose, glucose, and fructose provide only heterogeneous mixtures. The homogeneous solution of 1:1 Ce(IV)/glucamine system is active for DNA hydrolysis: the pseudo-first-order rate constant for the hydrolysis of thymidylyl(3'-->5')thymidine at pH 7.0 and 50 degrees C is 0.010 h-1, when [Ce(IV)]0 = [glucamine]0 = 10 mmol dm-3. The DNA-hydrolyzing activity decreases in the following order: glucamine > isomaltose, melibiose, gentiobiose >> palatinose, mannitol, sorbitol, galactitol.

Catalysis↗

PubMed1997

Mechanistic analogy between metal ion-catalyzed self-splicing of protein and RNA.

Recent studies have shown that RNA hydrolysis is remarkably promoted by metal ions and suitably designed metal complexes. We have found that autocleavage of dipeptides X-Ser and a tripeptide Gly-Ser-Ala is catalyzed by Zn(II) at 70 degrees C and pH 7.0. A mechanistic analogy between metal ion-catalyzed hydrolysis of peptides and RNA is suggested.

Cadmium↗

PubMed1997

Non-enzymatic hydrolyses of aryl esters of thymidine 3'-monophosphate as probes for the rate-determining step in DNA hydrolysis.

In order to shed light on the rate-limiting step in DNA hydrolysis, non-enzymatic hydrolyses of aryl esters of thymidine 3'-monophosphate have been kinetically examined. In alkaline solutions, these dinucleotide analogues were hydrolyzed far faster than was thymidylyl(3'-5')thymidine (TpT), indicating that the departure of the leaving group from the phosphorus atom is rate-limiting. The CeIV- and CeIV/PrIII combination-mediated hydrolyses of these analogues were also faster than the corresponding hydrolysis of the dinucleotide.

Cerium↗

PubMed1996

Very poor prognosis in cases with extravasation of the contrast medium during angiography.

BACKGROUND: The rebleeding of a ruptured intracranial aneurysm in the acute stage has been thought to indicate a very poor prognosis. In our experience, the outcome of patients with extravasation of the contrast medium is worse than that of patients with rerupture under circumstances other than angiography. We demonstrated the poorer outcome of the patients with extravasation, compared to that of the patients developing rerupture under circumstances other than angiography, and examined the factors that contributed to the poorer outcome of the patients with extravasation. METHODS: Among the 641 cases of ruptured intracranial aneurysm, we have handled over the past 10 years, 36 (5.6%) patients have rebled before surgery was performed. Thirteen patients rebled during angiography (Group I), and the remaining 23 patients rebled in other circumstances (Group II). We compared the outcome of both groups. RESULTS: The rebleeding occurred within 6 hours of the initial rupture in 29 (80%) patients. The outcome of Group I was significantly poorer than that of Group II (p < 0.05). In Group I, SD was achieved in only 1 patient and the remaining 12 patients died, while in Group II, 8 patients were in GR or MD, 2 were in SD, and the remaining 13 patients died. CONCLUSION: Because rebleeding during angiography most often occurs in the acute stage and because the outcome of patients with extravasation is very poor, we recommend that the performance of angiography be delayed at least between 3 and 6 hours after the initial rupture.

Adult↗

PubMed1996

Dinuclear lanthanum(III) complex for efficient hydrolysis of RNA.

A dinuclear La3+ complex hydrolyzes the phosphodiester bond in diribonucleotides efficiently under mild conditions. The rate of hydrolysis is remarkably accelerated on the complex formation between La3+ and TPHP (TPHP = N,N,N',N'-tetrakis [(2-pyridyl)methyl]-2-hydroxy-1,3-diaminopropane), and the highest activity is attained when the dinuclear structure is formed. The half-life of ApA hydrolysis by the dinuclear La3+ complex (1 mM) is 350 s, whereas that by the free La3+ ion (1 mM) is 23,000 s at pH 7.2 and 50 degrees C. The dinuclear La3+ complex is promising as a catalytic center of artificial nucleases.

Binding Sites↗

PubMed1996

The intracompartmental sorting of myosin alkali light chain isoproteins reflects the sequence of developmental expression as determined by double epitope-tagging competition.

In order to compare within the same cell the various degrees of specificity of myosin alkali light chain (MLC) isoproteins sorting to sarcomeres, a competition assay was established using double epitope tagging. Various combinations of two different MLC isoform cDNAs tagged with either a vesicular stomatitis virus VSV-G (VSV) or a medium T (mT) protein epitope were co-expressed in cultured cardiomyocytes from adult and neonatal rat ventricles. Expressed isoproteins were detected by means of anti-VSV and anti-mT antibodies and their sorting patterns were analyzed by confocal microscopy. The sorting specificity of MLC isoforms to sarcomeric sites was shown to increase in the order MLC3nm, to ML1sa, to MLC1sb, to MLC1f and MLC3f following the sequence of developmental expression. Expressed fast skeletal muscle isoforms (MLC1f and MLC3f) were always localized at the A-bands of myofibrils, while nonmuscle type (MLC3nm) was distributed throughout the cytoplasm. The slow skeletal muscle type (MLC1sa) showed a weak sarcomeric pattern if it was co-expressed with MLC3nm, but it was distributed throughout the cytoplasm when expressed in combination with MLC1f, MLC3f or the slow skeletal/ventricular muscle isoform (MLC1sb). The MLC1sb was localized at the A-bands when it was co-expressed with MLC3nm or MLC1sa, while it was also distributed to the cytoplasm if co-expressed with MLC1f or MLC3f. Further, expression of chimeric cDNAs revealed that the N-terminal lobe of each isoprotein is responsible for the isoform-specific sorting pattern.

Animals↗

PubMed1996

Non-traumatic arteriovenous fistulas of the scalp treated by a combination of embolization and surgical removal.

Three patients with non-traumatic arteriovenous fistulas (AVFs) of the scalp were treated by embolization using acrylate glue through the transarterial route or by direct puncture of the lesions and then surgical resection. Complete cure was achieved in all three patients. Selective angiography is indispensable in the correct diagnosis of scalp AVFs. Embolization facilitates surgical removal when necessary, and this combination is the treatment of choice for scalp AVFs.

Acrylates↗

PubMed1996

Transient monocular blindness during manual carotid compression for carotid-cavernous sinus fistulas--two case reports.

Transient monocular blindness occurred during manual carotid compression in two patients with a traumatic direct and a spontaneous dural arteriovenous carotid-cavernous sinus fistula. Ocular complication may occur during diagnostic or therapeutic carotid compression for carotid-cavernous sinus fistulas, so patients should be informed of this possibility. Ocular examination should be repeated during carotid compression to prevent sequelae of ischemic oculopathy.

Arteriovenous Fistula↗

PubMed1996

Vein of Galen aneurysmal malformation in a neonate treated by endovascular surgery--case report.

A male neonate with vein of Galen aneurysmal malformation developed fetal heart failure after a gestation period of 37 weeks. Labor was induced, but a cesarean section had to be performed because of fetal distress. His Apgar scores were 2/8 at birth. The boy required controlled ventilation due to generalized seizure and cyanosis. Neuroimaging revealed vein of Galen aneurysmal malformation with enormous arteriovenous shunt flows. Transarterial embolization was performed on days 4 and 6 to reduce the progressive high-output congestive heart failure. Three large feeders were occluded with interlocking detachable coils, markedly reducing the shunt flow. Although heart failure improved markedly, he died of pulmonary hemorrhage on day 12. Endovascular surgery can improve the prognosis of heart failure in the neonatal period less invasively than other treatment modalities, and may help to minimize ischemic brain damage and thus increase the possibility of normal brain maturation.

Arteriovenous Fistula↗