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Biomedical subjects

T Yoshimoto

Publications and source records attributed to T Yoshimoto.

At least 595 records · Page 33Linked to original sources
PubMed1993

Permissible temporary occlusion time in aneurysm surgery as evaluated by evoked potential monitoring.

To clarify the permissible time for temporary vascular occlusion during aneurysm surgery, we have undertaken a retrospective analysis of the results of intraoperative median nerve somatosensory evoked potential (SEP) monitoring in 97 patients with middle cerebral artery (MCA) (46 patients) or internal carotid artery (ICA) (51 patients) aneurysms. All patients underwent temporary vascular occlusion, lasting from 2 to 70 minutes, under the administration of a mixed solution of 20% mannitol with phenytoin and vitamin E. The mean occlusion time was 20.3 minutes for the MCA patients and 15.8 minutes for the ICA patients. The SEP disappeared during occlusion in 42 patients (30 MCA and 12 ICA). All but three eventually recovered the SEP to the baseline level after recirculation, and none of the 39 patients had postoperative sequelae. The time period from the start of occlusion until the complete loss of the SEP averaged 8.6 minutes among these 39 patients, and the occlusion time from total SEP loss until recirculation averaged 12 minutes. In the remaining 3 of the 42 patients (all 3 being ICA aneurysm patients), however, the SEP did not recover after recirculation and all 3 patients showed postoperative sequelae. In two of these three patients, vascular occlusions were performed at the multiple sites (i.e., at the ICA, MCA, anterior cerebral artery, and posterior communicating artery) and the SEP disappeared rapidly after the occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Improvement of cerebral blood flow and clinical symptoms associated with embolization of a large arteriovenous malformation: case report.

We report a patient with an unruptured, large arteriovenous malformation that was treated by staged, superselective embolization with liquid agents and by an investigation of the hemodynamic changes accompanying embolization. A 29-year-old man presented with headache and left upper quadrantanopsia. A neuroradiological study revealed a large right temporo-occipital arteriovenous malformation, and angiography disclosed poor filling of the adjacent vessels. In the venous phase, marked cortical reflux, suggesting venous hypertension, was also observed. Single photon emission computed tomography scanning with N-isopropyl-p-iodine-123- iodoamphetamine disclosed a low-perfusion area in the ipsilateral occipital and temporal lobes. After embolization, cerebral blood flow and the clinical symptoms attributed to ischemia improved. A follow-up study 1 year later demonstrated that the patient's improvement was stable. Single photon emission computed tomography confirmed that embolization achieves an improved cerebral blood flow.

Adult↗
PubMed1993

Combined endovascular and neurosurgical approach for paraclinoid internal carotid artery aneurysms.

The authors review the surgical management of nine complex paraclinoid aneurysms treated with the endovascular balloon catheter technique. With the patient under general anesthesia, the balloon catheter was guided into the feeding artery of the aneurysm by the Seldinger technique. After the aneurysm was exposed, the balloon was inflated temporarily to prevent premature rupture and to facilitate the dissection of the aneurysm. For the larger paraclinoid aneurysm, the double-lumen catheter was introduced into the cervical internal carotid artery (ICA). After temporarily trapping the aneurysm by balloon occlusion of the cervical ICA and clipping the intracranial ICA distal to the aneurysm, retrograde aspiration was performed to collapse the aneurysm. The complete collapse of the large aneurysm by this technique allows an easier dissection of the aneurysm and a safer application of suitable clips. Such a retrograde suction decompression method was used in six large aneurysms. Intraoperative digital subtraction angiography was performed in all cases after the aneurysmal clipping; in three aneurysms, repositioning the clip was required. Only one case of embolic complication was related to the vessel catheterization in this series, which was discovered during the operation. An embolectomy was performed immediately, and there were no postoperative sequelae. We conclude that the combined endovascular and neurosurgical approach, particularly for the large ICA aneurysms, which are difficult to control proximally, can be a useful method of treatment. To prevent complications related to thrombus formation, further refinement in the balloon catheter itself is still needed.

Adult↗
PubMed1993

Experimental investigations concerning a new liquid embolization method: combined administration of ethanol-estrogen and polyvinyl acetate.

A new embolization agent combining ethanol-estrogen and polyvinyl acetate was evaluated angiographically and histologically in 18 canine renal arterial systems. Peripheral vessels of less than 100 microns diameter were obliterated by thrombus induced by ethanol-estrogen, and larger vessels were obliterated by polyvinyl acetate casts and/or thrombus. This embolization method is easily controlled and has fewer adverse effects, so is suitable for intravascular applications, especially in the head and neck regions.

Animals↗
PubMed1993

Prospective study on the prevention of cerebral vasospasm by intrathecal fibrinolytic therapy with tissue-type plasminogen activator.

The authors have evaluated the efficacy of postoperative intrathecal injections of tissue-type plasminogen activator (tPA) in preventing cerebral vasospasm in patients with a diffuse thick subarachnoid hemorrhage (SAH). The present study examined 105 patients who underwent direct surgery within 48 hours of SAH and whose computerized tomography (CT) findings were classified as Fisher CT Group 3. Patients showing diffuse thick subarachnoid blood clots on CT with greater than 75 Hounsfield units (HU) were included in the tPA therapy group and those with below 75 HU comprised the control group. The surgical method was the same in both groups, and both groups had cisternal drainage instituted. On the day following the operation, the tPA group was given an intrathecal injection of tPA (2 mg), and this was continued for several days until all of the cisterns exhibited low density on CT scans. Follow-up angiography showed that 26 cases (87%) in the tPA group had no vasospasm, three (10%) had moderate vasospasm, and one (3%) had severe vasospasm. All four patients showing spasm on angiography were asymptomatic, and there were no cases of delayed ischemic neurological deficits (DIND). In contrast, there were 11 cases (15%) with DIND in the control group. In the tPA group, there was one case of SAH caused by drainage catheter removal, one with a small epidural hematoma, and one with subgaleal fluid accumulation; all of these were treated conservatively with favorable results. Overall, there were no infectious complications related to cisternal drainage and intrathecal injection of tPA. These results indicate that multiple intrathecal injections of small doses of tPA are effective and safe in preventing vasospasm. On the basis of this experience, the authors conclude that injection of 2 mg of tPA daily for 5 days (a total of 10 mg) is effective in preventing the development of vasospasm.

Adult↗
PubMed1993

[Experience with polyurethane intraurethral stents in aged patients].

A double Malecot-like 16F, polyurethane intraurethral catheter (IUC) was inserted 39 times in 25 patients between 68 and 91 years old (mean +/- SD: 77.5 +/- 5.5 years). Most of them were unfit for surgery because of severe illness or advanced age. All patients except 1 had either an indwelling catheter or a residual urine volume > 50ml at their first visit. The remaining one suffered from prostatic cancer and complained of pollakisuria and urinary incontinence. His symptoms were controlled well after ICU insertion and anticholinergic therapy. Twenty-nine insertions in 17 patients were considered successful, and the patients with successfully inserted stents voided without residual urine. Nine of 21 patients needed to take anticholinergic drugs. The mean duration of IUC use was 113 days in successful cases. In 9 out of 17 patients with an indwelling IUC for more than 112 days, the catheter became blocked by stones or clots. Therefore, we consider that the device should be changed after 110-120 days. Ten insertions failed for the following reasons: malposition, inappropriate IUC length, spontaneous migration to the bladder in patients with a short prostatic urethra, urinary retention due to underactive detrusor, and total incontinence and bleeding from prostatic cancer.

Aged↗
PubMed1993

[A case of tectal glioma].

A case of tectal glioma with mild choked disc is reported. An 11-year-old boy was admitted to our hospital because of visual disturbance and choked disc. Neurologically, the patient had nothing but choked disc. Magnetic resonance imaging (1.5T) was performed. Relative T1 weighted image showed a lesion of low signal intensity, and T2 weighted image showed high intensity, about 1.0 x 1.0 cm in size, at the pineal region. The sagittal view showed a mass at the tectum, and stenosis of the aqueduct. It was diagnosed as tectal glioma. Left occipital craniotomy was performed and the tumor was removed subtotally. Histological examination demonstrated a fibrillary astrocytoma. Radiochemotherapy was performed postoperatively. Tectal glioma is very rare. The differential diagnosis from germ cell tumor or pineal cyst is essential for treatment. The authors performed an operation in order to remove the tumor and determine the course of treatment.

Brain Neoplasms↗
PubMed1993

[A case of exogenous lipoid pneumonia probably due to domestic insecticide].

A 61-year-old female was admitted to our hospital because of cough, hemosputum and right chest pain. The P-A and L-R chest films revealed focal consolidation in the right upper filed and mass-like shadow in the right S3. Transbronchial lung biopsy specimens showed collections of lipid-laden macrophages. The lipid material of macrophages in broncholaveolar lavage fluid was stained yellow-orange with Sudan IV. The patient had no difficulty in swallowing and had no history of regular use of oily drugs. Fiberoptic bronchoscopy and chest CT showed no obstruction of bronchi. She had used much domestic insecticide with the doors closed before going to bed every summer and autumn for 10 years. We concluded that the domestic insecticide containing mineral oil had resulted in exogenous lipoid pneumonia. Her symptoms and abnormal shadows in chest X-ray film disappeared soon after antimicrobial chemotherapy was started. She is now healthy without recurrence.

Female↗
PubMed1992

Structure and chromosomal localization of human arachidonate 12-lipoxygenase gene.

Arachidonate 12-lipoxygenase introduces a molecular oxygen into the C-12 position of arachidonic acid to produce 12(S)-hydroperoxy-5,8,10,14-eicosatetraenoic acid. With the aid of cDNA probes for the enzyme, we isolated overlapping lambda clones encompassing the human 12-lipoxygenase gene and flanking regions from a human genomic library. The gene consists of 14 exons with 13 introns and spans approximately 15 kilobases of DNA. All the exon-intron junctions conform to the GT/AG rule. Neither a typical TATA box nor a CAAT box was found in approximately 1-kb sequence of 5'-upstream region of the translation initiation site. However, this region contains several regulatory elements including four GC boxes, two CACCC boxes, three AP-2 binding sequences, and a glucocorticoid-responsive element. The major transcription initiation site was determined by primer-extension analysis as an adenosine residue at 306 bases upstream from the translation initiation codon. The chromosomal localization of the human 12-lipoxygenase gene was examined by fluorescence in situ hybridization, and the gene was assigned to the sub-band p13.1 of chromosome 17.

Arachidonate 12-Lipoxygenase↗
PubMed1992

[Analysis on combined effect of X-rays with 5-FU on rat subcutaneous gliomas].

In a series of experiments on the combined use of radio- and chemotherapy for malignant glioma, X-rays combined with ACNU or 5-FU treatment caused a supra-additive effect on multicellular spheroids in vitro. In the present experiment, the effect of X-rays combined with 5-FU treatment on subcutaneously transplanted rat gliomas of RGC-6 cells was analyzed. The dose-survival curve for X-rays given to tumors in air-breathing rats was biphasic with a terminal slope (D0 = 4.3 Gy) that was parallel to that for tumors in previously killed rats. The hypoxic cell fraction thus obtained from the ratio of the surviving fraction in two parallel curves at 20 Gy was about 7% in the subcutaneous tumors in air-breathing rats. X-ray-induced, potentially lethal cellular damage recovered within 8 hours in these tumors. The surviving fraction of cells in the tumors decreased to a minimum at 4-6 hours after a 5-FU injection, but increased thereafter. A biphasic dose-response curve for 5-FU was also obtained for cells in these tumors, indicating the presence of 5-FU resistant cells. The effect of X-irradiation given at about 8 hours after a 5-FU injection was greater than the additive effect of both agents acting independently. This was true when an X-ray dose of more than 5 Gy was given.

Animals↗
PubMed1992

Molecular structure and function of the porcine arachidonate 12-lipoxygenase gene.

The gene encoding arachidonate 12-lipoxygenase was cloned from a porcine EMBL3 genomic library using a cDNA probe of the enzyme, and its nucleotide sequence was determined. The gene consists of 14 exons with 13 introns, and spans approximately 8 kilobases. Analysis of splice junctions indicated that all of the splice donor and acceptor sites conformed to the GT/AG rule. An approximately 1-kilobase region upstream of the coding sequence contains nine GC-boxes for potential Sp1-binding sites at positions -77, -135, -145, -165, -214, -636, -643, -684, and -813. There are two sets of AP-2 binding sequence at positions -234 and -402. Neither typical TATA box nor CCAAT box is found in this region. The transcriptional start site was determined by primer extension analysis, and was tentatively identified as a cytidine residue located 19 bases upstream from initiation codon. Southern blot analysis revealed the presence of one copy of 12-lipoxygenase gene per haploid genome. We found striking similarities in genomic organization as well as the promoter sequences between the porcine 12-lipoxygenase and the rabbit 15-lipoxygenase genes, suggesting that these genes are evolutionarily related.

Amino Acid Sequence↗
PubMed1992

Interstitial deletion of chromosome 16q: 16q22 is critical for 16q- syndrome.

Partial deletion of 16q is rare; to our knowledge only 12 cases have been published. Fryns et al. [Hum Genet 38:343-346, 1977] described the first of these cases and proposed a new clinical entity. Our patient was a girl and had many minor anomalies of the kind often observed in 16q- syndrome. Severe failure to thrive due to emesis and diarrhea were also observed. High resolution banding methods showed that the chromosome constitution of the patient was 46,XX,del(16)(q22.1q22.3). This suggests that 16q22 is critical for the syndrome.

Chromosome Deletion↗
PubMed1992

High serum IL-6 level reflects susceptible status of the host to endotoxin and IL-1/tumor necrosis factor.

Patients with high level of serum endotoxin did not necessarily develop into lethal shock, whereas some patients died of septic shock even when their serum endotoxin levels were low. These results indicate that limiting factor which determines the host to be endotoxin shock principally depends on the host susceptibility to endotoxin instead of serum endotoxin level. To understand this susceptible status of the host to endotoxin, we used Propionibacterium acnes primed mouse endotoxin shock model. We found that P. acnes-primed mice responded to low dose of LPS by enhanced production of IL-1 and TNF. And such mice were highly susceptible to the lethal shock inducing effect of IL-1 and/or TNF, which also induced high level of serum IL-6 in these mice. Therefore, measurement of serum IL-6 level provides us with the information of the preceding exposure of the host to either LPS or IL-1 and/or TNF and the highly susceptible status of the host to these stimuli. Based on these results obtained from animal model, we investigated the relationship between serum IL-6 levels and serum endotoxin levels in the patients with malignant hematologic disorders. We found that these patients fell into two groups; an endotoxin susceptible group, equivalent to P. acnes-primed mice, showing high level of serum IL-6 with low level of serum endotoxin, and a nonendotoxin susceptible group, equivalent to P. acnes-nonprimed mice, showing low or undetectable level of serum IL-6 with high level of serum endotoxin. We propose that the measurement of serum IL-6 level in the patients positive for endotoxin is a useful tool in evaluating diagnosis and prognosis of endotoxin shock.

Adolescent↗
PubMed1992

DNA fragmentation in focal cortical freeze injury of rats.

This study examined the appearance of double-strand DNA breaks in rat brain after a focal cortical freeze injury in vivo. DNA fragments of oligonucleosome size appeared 3 h after the injury, and increased in a time-dependent manner. At 24 h, the amount of DNA fragmentation reached a maximum and then declined. When nuclei from freeze-injured brain tissue were incubated with Ca2+ in vitro, increased endonuclease activity, which can cause DNA fragmentation, was found. These findings indicate that the activation of a Ca(2+)-dependent endonuclease may be involved in the evolution of freeze-traumatized brain tissue.

Animals↗
PubMed1992

Role and regulation of interleukin (IL)-2 receptor alpha and beta chains in IL-2-driven B-cell growth.

Substantial proportions of resting B cells constitutively express low levels of IL-2 receptor (IL-2R) alpha and/or beta chains. The expression of these chains is differentially regulated by anti-IgM and IL-2/IL-4. The anti-IgM induces IL-2R alpha chain expression, whereas each of the two cytokines induces IL-2R beta chain expression in a dose-dependent manner. Moreover, IL-2 induces the growth of B cells, when the cells were pretreated with IL-2 or IL-4 for 24 h. The magnitude of this IL-2-driven B-cell growth depends upon the level of IL-2R beta chain expression. Costimulation of the B cells with IL-2 and anti-IgM shifts the dose-response curve, and the cells proliferate at an IL-2 concentration as low as 40 pM. These results indicate that the levels of anti-IgM-induced IL-2R alpha chain and IL-2-induced IL-2R beta chain determine the sensitivity of the cells to IL-2.

Animals↗
PubMed1992

Methylated cytosine level in human liver DNA does not decline in aging process.

In order to ascertain a generality of the age-dependent decrease in DNA methylation level among different mammalian species, methylated cytosine contents in human liver and spleen DNA at different ages have been determined using high performance liquid chromatography (HPLC). Unexpectedly, the liver DNA revealed no appreciable decline with age while the spleen DNA showed a slight reduction. It indicates that a decrease of methylation level in genomic DNA is not a common denominator of age-related changes in mammals.

Adolescent↗