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Biomedical subjects

M Komiyama

Publications and source records attributed to M Komiyama.

At least 127 records · Page 7Linked to original sources
PubMed1996

[A case of rheumatoid factor-positive pachymeningitis].

We report a case of rheumatoid pachymeningitis involving the posterior fossa. A 71-year-old woman presented with headache, vertigo and dizziness. MRI demonstrated hypertrophic masses in the meninges of the left cerebellar tentorium, cerebellopontine angle and the fourth ventricle. Six months of treatment with betamethasone, prednisolone and azathioprine improved the patient's neurological status. Because an inappropriate immune process and systemic immune disease may cause idiopathic pachymeningitis, the performance of immunological studies for idiopathic cases is mandatory.

Aged↗
PubMed1996

[A case of middle cerebral artery occlusion caused by dissecting aneurysm].

We reported a case of middle cerebral artery occlusion caused by a dissecting aneurysm that was successfully treated by intra-arterial fibrinolysis. A 38-year-old man suddenly developed left hemiparesis and became confused. He was transferred to our hospital one hour and 27 minutes after the ictus. Right carotid angiogram (CAG) revealed aneurysmal dilatation of the horizontal portion of the middle cerebral artery and occlusion of the anterior trunk. Twelve million IU of tissue plasminogen activator was injected to fibrinolyze the thrombus of the occlusion site through a microcatheter. After this, the patient became alert and hemiparesis disappeared. It took three hours and 30 minutes to gain recanalization after the ictus. Right CAG obtained the next day demonstrated the patency of the anterior trunk and the characteristic finding of the dissecting aneurysm viz "double lumen" as a result of fibrinolysis of the thrombus in the false lumen. Right CAG obtained two weeks later demonstrated "string and pearl sign" instead of the "double lumen" as a result of partial thrombosis in the false lumen. Follow-up CAG obtained nine months after the ictus demonstrated marked reduction of the aneurysmal size as the result of progressing thrombosis of the false lumen. The characteristic angiographic findings of the dissecting aneurysm such as "double lumen" and "string and pearl sign" seemed to be mostly influenced by the status of the thrombus in the false lumen. In case of major cerebral arterial occlusion caused by the embolus or thrombus from the dissecting aneurysm, intra-arterial fibrinolysis seems to be a possible treatment modality, even though it is accompanied by the risk of giving rise to subarachnoid hemorrhage.

Adult↗
PubMed1995

Angiographic extravasation of contrast medium in acute "spontaneous" subdural hematoma.

Acute spontaneous subdural hematoma is very rare. We have encountered four such cases and verified the arterial origin of the bleeding at operation. None of the patients had a history of head trauma, and each had developed sudden onset of headache and other neurologic deficits, which simulate other cerebrovascular diseases. CT directly revealed subdural hematoma but gave no indication as to the source of the bleeding. Cerebral angiography was performed in all cases, with three of them showing localized extravasation of the contrast material into the subdural space. The extravasation was noted usually in the late arterial phase. This is a useful finding for diagnosing this disease and localizing the bleeding point. It is expected that with more routine use of cerebral angiography in cases of acute spontaneous subdural hematoma, extravasation of the contrast medium will be seen more frequently.

Acute Disease↗
PubMed1995

Hydrolysis of DNA and RNA through cooperation of two metal ions: a novel mimic of phosphoesterases.

The phosphodiester linkages in DNA and RNA are efficiently hydrolyzed through cooperation of the lanthanum(III) ion with the iron(III) or tin(IV) ion, although each of these metal ions exhibits poor activity. The conversion on the hydrolysis of adenylyl(3'-5')adenosine by the lanthanum(III)/iron(III) combination (10 mM each) at pH 7.0 and 50 degrees C for 5 min is 72 mol%, whereas the catalysis by the lanthanum or iron ion alone is only marginal. The activity of their combination in the hydrolysis of thymidyl(3'-5')thymidine is more than 15-fold greater than the sum of the activity of each of the two metal ions.

Catalysis↗
PubMed1995

Sequence-specific and hydrolytic scission of DNA and RNA by lanthanide complex-oligoDNA hybrids.

Totally synthetic and sequence-specific nucleases and ribonucleases, which hydrolyze DNAs and RNAs selectively at target sites, have been prepared. Lanthanide ions, which efficiently hydrolyze the phosphodiester linkages in nucleic acids, are attached to the 5'-end of synthetic DNA oligomers (sequence-recognizing sites) by use of an iminodiacetate ligand. Under physiological conditions, the hybrids selectively hydrolyze substrate DNA or RNA at the 3'-side of the sequence which is complementary with the DNA oligomers in the hybrids. The cerium(IV) ion is the most active as to DNA scission, whereas the europium(III), thulium(III), and lutetium(III) ions are the most effective for RNA scission. All the scissions proceed totally via hydrolysis of the phosphodiester linkages, in the same way as the scissions by natural nucleases and ribonucleases do. The artificial enzymes, which show far greater sequence-specificities than natural ones, exhibit high potential for application to molecular biology, biotechnology, and therapy.

Animals↗
PubMed1995

Endovascular treatment of an extracranial internal carotid artery aneurysm at the skull base with mechanically detachable coils--case report.

A 45-year-old male experienced a transient ischemic attack manifesting as left blurred vision and right hemiparesis. Angiography demonstrated an extracranial internal carotid artery aneurysm at the entrance of the carotid canal just above the C-1 vertebral arch. Intraluminal occlusion of the aneurysm was achieved with mechanically detachable coils under local anesthesia, and the carotid flow was preserved. There was no complication during or following the procedure. Treatment of aneurysms using detachable coils is an important alternative to surgical treatment when surgical access to the lesion is difficult.

Carotid Artery, Internal↗
PubMed1995

Variation of the right subclavian artery as the last branch of the aortic arch in two Japanese cadavers.

Two anomalous cases of the right subclavian artery were found in Japanese cadavers. In both cases, the right subclavian artery arose from the posterior wall of the aortic arch as its last branch, and ran rightwards between the esophagus and the vertebral column. The cases described belong to type G of the Adachi-Williams-Nakagawa-Takemura classification of aortic arch branching patterns.

Aged↗
PubMed1995

[Photocleavage of nucleic acids by photosensitizers--application to photodynamic cancer therapy].

Plasmid DNA has been efficiently photocleaved by sodium pheophorbides (Na-Phdes) a and b with visible light even in the absence of oxygen. Singlet oxygen production sensitized by Na-Phdes a and b has not been observed in the aqueous media. Electron transfer from DNA bases, guanine and adenine, to the porphyrin ring in the singlet excited state has been demonstrated. Fluorescence microscopic observation has shown a rapid incorporation of Na-Phde a into nuclei, mitochondria, and lysosome of human oral cells. In contrast, Na-Phde b has been incorporated only into the plasma membrane. Fluorescence intensity of Na-Phde a has rapidly decreased during microscopic observation, indicating that some photochemical reactions take place in the organelle. Fluorescein-attached oligonucleotide (11 mer) has bound covalently to a complementary strand DNA (28 mer) by visible light irradiation in aqueous media. This oligonucleotide with liposome treatment can be incorporated into nucleoli of cultured human keratinocytes, and its strong fluorescence has quickly decayed by irradiation. The first photohydrolysis has been achieved by several naphthol derivatives with visible light. Thus naphthol derivatives can be potent as the catalytic site of artificial photonuclease.

Chlorophyllides↗
PubMed1995

[A case report of dural sinus thrombosis: direct thrombolytic therapy using endovascular surgery].

Dural sinus thrombosis, a relatively rare disease, is difficult to diagnose because of variable symptomatic manifestations. We successfully treated a case of dural sinus thrombosis by direct thrombolysis using an endovascular technique in combination with postoperative anticoagulant therapy. The patient, a 19-year-old female, developed a headache affecting her whole head on December 13, 1993. She was admitted to our hospital the next day. Neurological examination upon admission revealed no neurological abnormalities, nor was there any abnormality in CT scan, either plain or enhanced, taken on the day of admission. The patient's consciousness deteriorated in the early morning of December 22. MRI and cerebral angiography revealed thrombi from the confluence of the sinuses to the right transverse and sigmoid sinus, with disturbed circulation through deep cerebral veins. Systemic thrombolytics, steroid and mannitol were started, but, on the next day, the third ventricle was compressed by bilateral swelling of the basal ganglia, with hydrocephalus. Since her consciousness deteriorated further despite ventricular drainage and barbiturate therapy, direct thrombolytic therapy was performed on December 25. A catheter was placed in the superior sagittal sinus, and 600,000 units of urokinase was locally injected, followed by postoperative anticoagulant therapy. The patient's condition improved rapidly. On CT scan, the bilateral swelling of the basal ganglia disappeared along with the hydrocephalus. At about 1 month after endovascular surgery, MRI and cerebral angiography revealed recanalization of the deep cerebral veins, straight sinus and confluence of sinuses with improved opacification of the left transverse sinus, although the right transverse sinus was found to be re-occluded.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Transient involuntary movement of the leg (monoballismus) during cerebral angiography.

Transient involuntary movement of the leg developed during diagnostic or therapeutic angiography in five patients. The movement was jerky, brisk flexion/extension of the hip and knee joints on the side contralateral to acute ischemia. This movement may occur as a result of thromboembolic cerebral ischemia or as an ischemic complication of angiography.

Adult↗
PubMed1995

Acetylacetonato-lanthanide complexes as eminent catalytic sites for artificial ribonucleases.

Acetylacetonato complexes of lutetium, ytterbium, thulium, and europium ions efficiently hydrolyze the phosphodiester linkage in adenylyl(3'-5')adenosine. The pseudo first-order rate constant (3.2 x 10(-2) h-1) at pH 7.2 and 30 degrees C for the 1:1 lutetium-acetylacetonato complex (0.5 mmol dm-3) is close to the value (3.5 x 10(-2) h-1) for free lutetium ion of the same concentration. Potentialities of these complexes as the catalytic sites of artificial ribonucleases are indicated.

Binding Sites↗
PubMed1995

Dinuclear metal complexes for the efficient RNA hydrolysis.

Dinuclear Zn(II) and La(III) complexes with TPHP efficiently hydrolyze a dinucleotide, ApA, under mild conditions (TPHP = N, N, N', N'-tetrakis[(2-pyridyl)-methyl]-2-hydroxy-1,3-diaminopropane). [Zn2(TPHP)]3+ hydrolyzes ApA with an extremely high activity; The pseudo-first-order rate constant is 8.4 x 10(-4) h-1 at pH 7, 50 degrees C when [[Zn2 (TPHP)]3+] = 2.5 mM. Free Zn(II) ion shows no hydrolysis activity under the conditions. Enormous acceleration of the hydrolysis by the dinuclear complex formation was also observed for La(III) ion. Its activity for the ApA hydrolysis is 100-fold greater than that of free La(III) ion. These dinuclear complexes are promising for the active sites of artificial ribonucleases.

Binding Sites↗
PubMed1995

Synergism of Ce (IV) and Pr(III) for the fastest non-enzymatic DNA hydrolysis ever.

By the synergistic catalysis of Ce4+ and Pr3+, DNA is efficiently hydrolyzed at so far the highest rate. When [Ce4+] = 10 mM and [Pr3+] = 5 mM, the half-life of dinucleotide hydrolysis at pH 7 and 50 degrees C is only 24 min. This catalytic activity is 9 times as large as that of Ce4+, which is the only prominent catalyst hitherto reported. The Ce(4+)-Nd3+ combination is also effective. These bimetallic catalytic systems are eminent tools for the future molecular biology and biotechnology.

Catalysis↗