Biomedical subjects

K Imoto

Publications and source records attributed to K Imoto.

At least 127 records · Page 7Linked to original sources

PubMed1991

Malignant melanocytic schwannoma of the nasopharynx.

A rare case of malignant melanocytic schwannoma in the nasopharynx is presented. Light microscopy showed proliferation of spindle-shaped tumor cells with mitoses. The essential histological hallmark was melanin deposition. Electron-microscopic examination confirmed the schwannian differentiation of the tumor cells. The patient has remained well without evidence of metastasis or local recurrence of the tumor 18 months after the excision of the neoplasm.

Humans↗

PubMed1991

[Dissecting aortic aneurysm associated with myonephropathic-metabolic syndrome and hypercalcemia].

A forty-two years old male underwent an aortic arch replacement for an emergency treatment of dissecting aortic aneurysm (DeBakey type I). Separate cardiopulmonary bypass was used with main arterial inflow cannula inserted to right femoral artery. After the operation, ischemia of the right lower extremity led to acute renal failure due to myonephropathic-metabolic syndrome. Peritoneal dialysis, hemodialysis, and continuous arterio-venous hemofiltration were performed. Renal failure improved gradually. At the diuretic phase serum calcium concentration began to rise. Inspite of large amount of fluid and furosemide injection it became higher and finally reached to 20 mg/dl level. Calcitonin injection (320 mu/day) was very effective. In 2 months after surgery serum creatinine and calcium concentrations went down to normal range. Abnormalities in calcium metabolism are frequent in rhabdomyolysis-induced acute renal failure. However, it is rare to encounter such a remarkable hypercalcemia as seen in this patient. When treating MNMS we should pay attention to the changes of serum calcium concentration.

Acute Kidney Injury↗

PubMed1990

Spontaneous and agonist-induced openings of an acetylcholine receptor channel composed of bovine muscle alpha-, beta- and delta-subunits.

During the development of mammalian muscle the gamma-subunit of the nicotinic acetylcholine receptor (AChR) is replaced by the epsilon-subunit to produce well-defined alterations in the conductance and gating of the channel. To gain a better understanding of the functional role of the gamma- and epsilon-subunits, we have studied the properties of an AChR channel lacking these subunits. The AChR expressed in Xenopus oocytes injected with the bovine alpha-, beta- and delta-subunit-specific mRNAs (referred to as alpha beta delta-AChR) is unusual in that its channel opens spontaneously at a high frequency in the absence of agonist. From a comparison of the alpha beta delta-AChR with complete receptors containing either the gamma- or epsilon-subunit, we conclude that the gamma- and epsilon-subunits influence most channel properties, including agonist binding, and are especially important for stabilizing the closed state of the unliganded receptor channel. The alpha beta delta-AChR can form when a complete set of four subunit-specific mRNAs is injected. The ease with which it is assembled raises the possibility that the alpha beta delta-AChR contributes to some of the variations in receptor properties that occur during development.

Animals↗

PubMed1990

Intraosseous glomus tumor in the sacrum. A case report.

Primary intraosseous glomus tumor is rare and may occur in the medullary cavity of bone. A 22-year-old woman with a one-year history of spontaneous and persistent sacral pain was found to have an intraosseous glomus tumor in this unusual location. Curettage was followed by complete relief from pain. This case of glomus tumor originating in the sacrum is thought to be the first reported in the world literature.

Adult↗

PubMed1990

[Report of a case which survived rupture in a hepatic artery mycotic aneurysm after aortic valve replacement].

A case in which rupture of a hepatic artery aneurysm occurred 4 months after aortic valve replacement because of aortic regurgitation due to infective endocarditis (IE) is reported. The patient was a 41-year-old male who underwent aortic valve replacement and closure of an abscess cavity of the Valsalva's sinus because of aortic regurgitation and an abscess of the Valsalva's sinus complicated with active IE. His postoperative course was good with no fever. Four months postoperatively, rupture of an aneurysm of the left intrahepatic artery occurred suddenly, and the patient's life was saved by resection of the lateral segment of the left lobe of the liver. Histologically, the wall structure of the aneurysm was not preserved, infiltration of neutrophils was seen in part of the wall, and a mycotic aneurysm of the left hepatic artery within the liver cause by IE was diagnosed. In Japan, only four cases, including the present one, of mycotic aneurysm of the hepatic artery have been reported in the literature examined, and this was the first case in which the patient's life as saved after a rupture. It is essential when observing the course of IE patients to bear in mind at all times that such a complication might occur.

Adult↗

PubMed1990

[Tricuspid annuloplasty and right ventricular function in mitral valve disease].

From 1985 to 1987, we examined relationship between the lesion of tricuspid valve and right ventricular function in 31 patients (male: 9, female: 22) with mitral valve disease. The median age at operation was 52 years (range 37-69 years). Group I consisted of 17 patients (MS: 10, MSR: 5, MR: 2) accompanied with tricuspid regurgitation (TR) and Group II 14 patients (MS: 12, MSR: 2) without TR. In all cases of Group I tricuspid annuloplasty (TAP) were performed correctly. De Vega methods were done in 12 cases and Carpentier rings were used in 5 cases. Cardiac catheterization was done before and after operation. And right ventricular volume was measured by right ventricular angiography. In both groups pulmonary capillary wedge pressure, pulmonary artery pressure and cardiac index were improved postoperatively. Pulmonary artery resistance (PAR) and total pulmonary resistance (TPR) in Group I were significantly higher before operation but there were no difference between two groups postoperatively. Right ventricular end-diastolic volume index (RVEDVI) and right ventricular end-systolic volume index (RVESVI) in Group I were significantly improved postoperatively, but in Group II these were within normal range both pre- and postoperatively. Preoperative PAR was correlated inversely with postoperative right ventricular ejection fraction (RVEF). It means that patients with severe pulmonary vascular lesion had postoperative lower right ventricular function. In both groups, RVESVI was in inverse correlation with RVEF pre- and postoperatively. In both groups, there was an inverse correlation between the per cent change of RVESVI and that of RVEF. This means that RVESVI influenced right ventricular pump function.

Adult↗

PubMed1990

[An aorto-coronary bypass graft operation of left coronary ostial stenosis due to aortitis syndrome].

A 24-year-old female with unstable angina due to aortitis syndrome was reported. The coronary-arteriogram in hospital showed 75 percent stenosis of the left coronary ostium. Following two months' steroid therapy for active inflammation, aortocoronary bypass graft was implanted. After the operation. This patient became free from angina attack. Steroid therapy was continued postoperatively as well. The coronary-arteriogram taken seven months after the operation, revealed the patency of the graft.

Adult↗

PubMed1990

[A case of chronic traumatic aneurysm of the descending thoracic aorta with the aberrant right subclavian artery].

A 59-year-old man had developed gradual prominence of the aortic knob in a chest X-ray film after a blunt chest trauma. Two and a half years after trauma, an angiogram revealed the aberrant right subclavian artery and a saccular aneurysm at the thoracic descending aorta just distal to it. It was treated with patch closure of the entrance of the aneurysm under a temporary bypass. Pathological findings were tearing off of a medial layer of the aorta. Postoperative course of this case was excellent. It must be noticed that the traumatic thoracic aortic aneurysm had a high possibility of rupture even in the chronic stage.

Aorta, Thoracic↗

PubMed1990

[Evaluation of the thromboexclusion technique for thoracic aortic aneurysms].

From 1981 to 1987 most of DeBakey III type dissecting aneurysms and a part of descending aortic aneurysms were treated by thromboexclusion technique. The effects of the operation by thromboexclusion technique on the patients were compared with those of the operation by temporary bypass technique. Blood loss during an operation was smaller and blood pressure during an operation was more stable in the thromboexclusion technique group, although the difference was not statistically significant. Furthermore, no paraplegia was observed in the thromboexclusion technique group. The respiratory support period was longer and the number of patients with postoperative myocardial injury was greater in the thromboexclusion technique group, although the difference was not statistically significant. Ten patients treated by thromboexclusion techniques were examined by computed tomography. In 7 out of 10 patients (70%), thrombosis occurred in the false lumen of dissecting aneurysm or in the aneurysmal lumen of descending aortic aneurysm. When only the patients without the leakage of blood into the aneurysm through the permanent aortic clamp were examined, thrombosis was observed in 100% of them. Even though the blood flow was reversed, thromboexclusion technique did not have a bad effect on renal function in the long-term. Postoperatively, however, progressive hypertrophy of the left ventricle was recognized, and furthermore, an injury to the aortic wall caused by permanent aortic clamp was observed at an autopsy. This suggests that further long-term follow-up of patients treated by thromboexclusion technique is necessary.

Aged↗

PubMed1989

Potassium channels from NG108-15 neuroblastoma-glioma hybrid cells. Primary structure and functional expression from cDNAs.

The complete amino acid sequences of two potassium channel proteins from NG108-15 neuroblastoma-glioma hybrid cells have been deduced by cloning and sequencing the cDNAs. One of these proteins (NGK2) is structurally more closely related to the Drosophila Shaw gene product than to the Shaker and Shab gene products, whereas the other (NGK1) is identical with a rat brain potassium channel protein (BK2) which is more closely related to the Drosophila Shaker gene product. mRNAs derived from both the cloned cDNAs, when injected into Xenopus oocytes, direct the formation of functional potassium channels with properties of delayed rectifiers.

Amino Acid Sequence↗

PubMed1989

Primary structure and functional expression of the cardiac dihydropyridine-sensitive calcium channel.

In cardiac muscle, where Ca2+ influx across the sarcolemma is essential for contraction, the dihydropyridine (DHP)-sensitive L-type calcium channel represents the major entry pathway of extracellular Ca2+. We have previously elucidated the primary structure of the rabbit skeletal muscle DHP receptor by cloning and sequencing the complementary DNA. An expression plasmid carrying this cDNA, microinjected into cultured skeletal muscle cells from mice with muscular dysgenesis, has been shown to restore both excitation-contraction coupling and slow calcium current missing from these cells, so that a dual role for the DHP receptor in skeletal muscle transverse tubules is suggested. We report here the complete amino-acid sequence of the rabbit cardiac DHP receptor, deduced from the cDNA sequence. We also show that messenger RNA derived from the cardiac DHP receptor cDNA is sufficient to direct the formation of a functional DHP-sensitive calcium channel in Xenopus oocytes. Furthermore, higher calcium-channel activity is observed when mRNA specific for the polypeptide of relative molecular mass approximately 140,000 (alpha 2-subunit) associated with skeletal muscle DHP receptor is co-injected.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1989

[A case of ruptured aneurysm of the sinus of Valsalva with bacterial endocarditis].

A 21-year-old male with ruptured aneurysm of sinus of Valsalva caused by bacterial endocarditis is presented. The patient complained of palpitation and a attack of fever. Continuous murmur was heard with a thrill at the third intercostal space of the left sternal border. On plain chest x-ray film pulmonary congestion and increase in pulmonary flow were observed. Cardiac catheterization showed step up of oxygen contents at the level of right ventricle and left to right shunt of 36.5%. Aortography demonstrated the aneurysm of the sinus of Valsalva ruptured to right ventricle. The operation was performed by right ventricular approach. Aneurysmal sac was resected and its orifice was closed with mattress sutures. Bacteriological examination at the time of operation revealed Staphylococcus aureus. Postoperative course was uneventful.

Adult↗

PubMed1988

Rings of negatively charged amino acids determine the acetylcholine receptor channel conductance.

The structure-function relationship of the nicotinic acetylcholine receptor (AChR) has been effectively studied by the combination of complementary DNA manipulation and single-channel current analysis. Previous work with chimaeras between the Torpedo californica and bovine AChR delta-subunits has shown that the region comprising the hydrophobic segment M2 and its vicinity contains an important determinant of the rate of ion transport through the AChR channel. It has also been suggested that this region is responsible for the reduction in channel conductance caused by divalent cations and that segment M2 contributes to the binding site of noncompetitive antagonists. To identify those amino acid residues that interact with permeating ions, we have introduced various point mutations into the Torpedo AChR subunit cDNAs to alter the net charge of the charged or glutamine residues around the proposed transmembrane segments. The single-channel conductance properties of these AChR mutants expressed in Xenopus laevis oocytes indicate that three clusters of negatively charged and glutamine residues neighbouring segment M2 of the alpha-, beta-, gamma- and delta-subunits, probably forming three anionic rings, are major determinants of the rate of ion transport.

Amino Acid Sequence↗

PubMed1988

Close correlation between restriction fragment length polymorphism of the L-MYC gene and metastasis of human lung cancer to the lymph nodes and other organs.

Restriction length fragment polymorphism of the L-MYC gene was examined in DNAs from lung cancer tissues and normal tissues of 51 Japanese patients with lung cancer. In individual patients, no difference was seen between the restriction length fragments of the two alleles of L-MYC [6-kilobase (kb) and 10-kb fragments in EcoRI digests] in lung cancer tissues and normal tissues. But a striking correlation was found between the restriction length fragment polymorphism pattern of L-MYC and the extent of metastasis, particularly to the lymph nodes at the time of surgery: Patients with only the L band (10 kb) had few lymph node metastatic lesions, whereas patients with either the S band (6 kb) or the S and L bands almost always had lymph node metastatic lesion. A similar correlation was found between the presence of the S band and metastases to other organs. This correlation was particularly marked in cases of adenocarcinoma. These results indicate a clear genetic influence on metastases and a consequent poor prognosis for certain patients of lung cancer; L-MYC restriction length fragment polymorphism is thus shown to be a useful marker for predicting the metastatic potential of human lung cancer.

Adult↗

PubMed1988