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Biomedical subjects

K Sakamoto

Publications and source records attributed to K Sakamoto.

At least 523 records · Page 29Linked to original sources
PubMed1994

[Relief of pulmonary venous obstruction for asplenia syndrome associated with total anomalous pulmonary venous connection in neonates and infants].

Five patients of asplenia syndrome with pulmonary venous obstruction underwent TAPVC repair in the period of neonates (4 patients) and infant (1 patient). They also underwent associated procedures to reconstruct or adjust pulmonary blood flow (systemic-pulmonary shunts in 2, bilateral PDA banding in 1, pulmonary artery banding in 1) in accordance with individual anatomy of the pulmonary arteries. In four of them, they required subsequent surgical procedures for reduction of pulmonary blood flow because of intractable heart failure due to increase in pulmonary blood flow mostly at the early postoperative period. The increasing pulmonary blood flow was successfully controlled by early reduction procedures (1 patient: extrathoracically adjustable PA banding, 1 patient: tightening of shunt graft) in two patients. However, one patient died in the early postoperative period because of moribund preoperative condition. The remaining one patient underwent PA banding three month after the first operation, but died in late period due to heart failure. These results suggest that the adjustment of pulmonary blood flow is critically important for management of the patients of asplenia syndrome with TAPVC after the operation, and early decision of PA band re-adjustment (or other procedures to decrease pulmonary blood flow) is mandatory to improve the results.

Abnormalities, Multiple↗
PubMed1994

[A case of malignant localized chest wall mesothelioma accompanying with abdominal aortic aneurysm].

The patient was a 78-year-old man with a history of large painful left lower lateral chest wall tumor that was fist sized, while he had large abdominal aortic aneurysm. Because of high age, two staged operation was done. Initially chest wall tumor was resected. The defect was 11 x 11 cm in sized. The reconstruction of the defect was made with Marlex mesh. The microscopical findings was biphasic malignant mesothelioma. Fourty one days later abdominal aortic aneurysm was excised and the aorta was reconstructed using a Y shaped artificial graft. Post-operative course was uneventful.

Aged↗
PubMed1994

[Study of cardiac function in first stage examination of RA-700. RA-700 Clinical Study Group].

There are many studies in the literature on the subject of anti-neoplastic drugs for acute and chronic cardiac toxic function. It is important to check previously the cardiac toxicity of the new anti-neoplastic drugs. Now we have had a chance to study the first stage examination of RA-700, isolated from Rubia akane or Rubia cordifolia. Then we tried to study several kinds of parameters, for instance ECG, ultrasonic cardiograms and arterio-grams on cardiac toxicities of RA-700. We injected the first group of neoplastic patients only once with RA-700, while in the second group, we injected them with RA-700 for 5 consecutive days (see our previous report.) In the present study, we made some conclusions about the administration of RA-700. 1) Changes in cardiac function were noted in both groups. 2) Changes in blood pressure, sigma QRS, ejection fraction, and fractional shortening of the second group tended to be more extreme than those of the first group. Care for continuity is a concern with long-term and high doses of RA-700. 3) Because of the small sample, we could find no relationship between the changes in cardiac function and the injection doses of RA-700. 4) Therefore, the cardiac function must be checked by giving anti-neoplastic drugs to neoplastic patients.

Adult↗
PubMed1994

[Reoperation after correction of total anomalous pulmonary venous connection: particularly for postoperative pulmonary vein stenosis].

Postoperative pulmonary vein stenosis is a major complication after the correction of the total anomalous pulmonary venous connection. Six patients developed this complication 2 to 3 months after surgery. Five underwent reoperation (3 had the third operations) with only one survivor. Risk factors for developing the stenosis were 1. small common pulmonary vein with small branches occurring in the patients with the ages at the operation below 2 days and accordingly with the infradiaphragmatic connection and 2. Y-shaped common pulmonary vein with the confluence situated far below the left atrium. Turbulence seemed the major cause of the intimal thickening occurring in the common pulmonary vein shortly distant from the orifices of the branches. Typically the anastomotic orifice was not narrowed. Relief of the stenosis was done by the excision of the hypertrophied intimal tissue frequently cutting into the branches. Severe stenosis recurred in 4 patients necessitating another operation in 3 patients which was fatal in two. Prevention is important. Creation of a large anastomosis with the incision not extending into the branches and the use of the absorbable suture materials were effective. In the infradiaphragmatic connection incorporation of the divided stump of the descending vein into the anastomosis and a T-shaped incision of the left atrium were also important.

Constriction, Pathologic↗
PubMed1993

Inhibition of rat mammary carcinogenesis by inositol hexaphosphate (phytic acid). A pilot study.

Since phytic acid (inositol hexaphosphate, InsP6) and inositol (Ins) have been demonstrated to have anti-tumor and anti-cell proliferative action in several experimental models of carcinogenesis, in a pilot study we have examined their effect on 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumor model. Starting a week prior to induction with DMBA, the drinking water of female Sprague-Dawley rats was supplemented with either: 15 mM InsP6, 15 mM Ins, or 15 mM InsP6 + 15 mM Ins; a control group received no inositol compounds. Animals (55-day-old) were given a single dose of DMBA (20 mg) in 1 ml of sesame oil by oral intubation. Four additional groups not receiving DMBA, but drinking tap water, InsP6, Ins, or InsP6 + Ins of the same molarity as experimental groups were observed for the duration of the study to monitor for any putative toxicity following this long-term treatment. As opposed to the DMBA-only group, rats treated with InsP6 +/- Ins showed a 48% reduction in the number of tumors/tumor bearing animal (tumor multiplicity) and a 40% reduction in the number of tumors/rat. In contrast to 20% rats in DMBA-only group, only 0-8% animals in the treatment group had 5 or more tumors. Likewise, the tumor incidence was reduced by 19% in InsP6 +/- Ins as compared to control untreated animals. The tumors in the treated groups were also 16% smaller in size. Data from this pilot study suggest that in addition to being effective against colon cancer, InsP6 +/- Ins may be protective against mammary carcinoma as well; additional studies are however warranted.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1993

Mechanisms of the inhibition of reverse transcription by unmodified and modified antisense oligonucleotides.

We demonstrated that unmodified and modified (phosphorothioate) oligonucleotides prevent cDNA synthesis by AMV or HIV reverse transcriptases. Antisense oligonucleotide/RNA hybrids specifically arrest primer extension. The blockage involves the degradation of the RNA fragment bound to the antisense oligonucleotide by the reverse transcriptase-associated RNase H activity. However, the phosphorothioate oligomer inhibited polymerization by binding to the AMV RT rather than to the template RNA, whereas there was no competitive binding of the phosphorothioate oligomer on the HIV RT during reverse transcription.

Animals↗
PubMed1993

A modified uridine in the first position of the anticodon of a minor species of arginine tRNA, the argU gene product, from Escherichia coli.

The argU (dnaY) gene product, a minor tRNA(Arg), from Escherichia coli has the anticodon N*CU with an unidentified modified nucleoside N* in position 34 [Kiesewetter, S., Fisher, W. & Sprinzl, M. (1987) Nucleic Acids Res. 15, 3184]. In the present study, argU tRNA was purified from E. coli A19 strain and nucleoside N* was characterized by the TLC and HPLC analyses. Nucleoside N* was found to be different from any naturally occurring modified nucleosides. From unfractionated E. coli tRNA species, nucleoside N* was prepared in an amount sufficient for 1H-NMR experiments. By the analyses of one-dimensional and two-dimensional NMR spectra, nucleoside N* was suggested to be 5-methylaminomethyluridine (mnm5U), which was confirmed by comparison with a chemically synthesized preparation of mnm5U. Thus, the occurrence of mnm5U in mature tRNA was found for the first time. Further, the modification of U(34) to mnm5U in this tRNA was found to contribute to the strict recognition of two degenerate codons terminating in A and G.

Anticodon↗
PubMed1993

Effects of ethanol on contractile response of gall bladder isolated from guinea pig.

The effects of ethanol treatment in vitro and in vivo on gall bladder contraction were investigated using gall bladder strips isolated from guinea pigs. In vitro pretreatment of the strips with ethanol at a concentration of over 50 mM significantly attenuated the reactivity and sensitivity of contractile responses to KCl, acetylcholine and histamine in a concentration-dependent manner. Indomethacin treatment or removal of extracellular calcium remarkably reduced gall bladder contractile response to acetylcholine. The depressive effect of ethanol in vitro on gall bladder contraction was also noted in the presence of indomethacin or absence of calcium in the medium. The concentration-response curve of calcium-induced contraction in 40 mM KCl-depolarized gall bladder strip shifted to the right on pretreatment with ethanol. In the case of strips following the chronic administration of 3% ethanol solution ad libitum for 4 weeks, contractile responses to KCl, acetylcholine and histamine did not differ, compared to those in the pair-fed group. This chronic ethanol administration induced tolerance to the acute inhibitory effect of ethanol on gall bladder contractile responses to the agonists. Ethanol is thus shown to exert direct inhibitory action on gall bladder contraction by lowering the calcium sensitivity of the contractile apparatus of smooth muscle; it is unlikely that ethanol consumption would affect gall bladder motility in vivo, owing to the tolerance produced toward the acute inhibitory action of ethanol.

Acetylcholine↗
PubMed1993

Chemical modification and mutagenesis studies on zinc binding of aminoacyl-tRNA synthetases.

Thermus thermophilus methionyl-tRNA synthetase consists of two identical subunits with a potential Zn(2+)-binding sequence of Cys-X2-Cys-X13-Cys-X2-His (Nureki, O., Muramatsu, T., Suzuki, K., Kohda, D., Matsuzawa, H., Ohta, T. Miyazawa, T., and Yokoyama, S. (1991) J. Biol. Chem. 266, 3268-3277). Upon chemical modification of the 3 Cys residues of T. thermophilus MetRS with sodium p-(hydroxymercuri)phenylsulfonate, one Zn2+ ion was released from one subunit of the molecule, as monitored with 4-(2-pyridylazo)resorcinol. Site-directed mutagenesis of Cys and His residues in the Zn(2+)-binding sequence reduced the aminoacylation activity; the kcat value was markedly decreased, and the Km values for L-methionine and tRNAf(Met) were increased. Similarly, Cys modification released two Zn2+ ions from T. thermophilus and Escherichia coli isoleucyl-tRNA synthetases and E. coli threonyl-tRNA synthetase, which have Zn(2+)-binding motifs, and impaired their activities. By contrast, three other aminoacyl-tRNA synthetases that lack Zn(2+)-binding motif neither released Zn2+ ion nor lost their activities upon Cys modification. These results indicate that the Zn(2+)-binding sequences are important for catalysis and recognition in the aminoacylation reactions of a subgroup of aminoacyl-tRNA synthetases.

Acylation↗
PubMed1993

Antagonist for atrial natriuretic peptide receptors ameliorates glomerular hyperfiltration in diabetic rats.

To evaluate the possible contribution of atrial natriuretic peptide (ANP) to the development of glomerular hyperfiltration, we examined the effect of non-peptide competitive antagonist for biological receptors of ANP, HS-142-1, on glomerular filtration rate (GFR) and renal plasma flow (RPF) in diabetic rats. Increased GFR and RPF in diabetic rats were significantly ameliorated by the injection of HS-142-1, while blood pressure remained unchanged. Urinary cyclic GMP excretion was significantly higher in diabetic rats than in control rats and HS-142-1 decreased urinary cGMP excretion significantly. These results indicate that atrial natriuretic peptide contributes to the development of glomerular hyperfiltration and hyperperfusion in diabetes and HS-142-1 might be useful in the treatment of them.

Animals↗
PubMed1993

Regulation of fatty acid synthase gene transcription. Sequences that confer a positive insulin effect and differentiation-dependent expression in 3T3-L1 preadipocytes are present in the 332 bp promoter.

We have previously reported induction of fatty acid synthase (FAS) gene expression by insulin and adipocyte differentiation in 3T3-L1 cells. In order to identify sequences responsible for insulin regulation of the FAS gene, chimaeric constructs containing serial deletions of the 5'-flanking region of the rat FAS gene ligated to the chloramphenicol acetyltransferase (CAT) reporter gene were prepared and transfected into 3T3-L1 cells. Plasmids containing 2100 (-2100CAT), 1400 (-1400CAT), 1009 (-1009CAT) and 332 (-332CAT) bp of FAS 5' flanking sequences exhibited comparable basal CAT activities in 3T3-L1 preadipocytes. This activity was 3-fold higher when these constructs were transiently transfected into 3T3-L1 adipocytes. Stably transfected 3T3-L1 cells also exhibited a 3-fold increase in CAT activity upon adipocyte differentiation, indicating that sequences required for the differentiation-dependent increase in FAS expression are located within the 332 bp promoter. Treatment with 10 nM insulin increased CAT activity by 2.1 +/- 0.2-, 2.6 +/- 0.1-, 2.0 +/- 0.2- and 1.7 +/- 0.2-fold respectively in 3T3-L1 adipocytes transiently transfected with -2100CAT, -1400CAT, -1009CAT and -332CAT plasmids. CAT activity was increased by 3.0 +/- 0.3- and 3.5 +/- 0.6-fold respectively by insulin treatment in adipocytes stably transfected with -2100CAT and -1009CAT plasmids. When insulin-responsive H4IIE hepatoma cells were transiently transfected with -2100CAT, -1400CAT, -1009CAT and -332CAT plasmids and then treated with 10 nM insulin, CAT activity increased by 3.1-, 3.1 +/- 0.8-, 3.0 +/- 0.7- and 2.3 +/- 0.5-fold respectively in serum-free media, and by 2.6 +/- 0.4-, 3.3 +/- 0.9-, 3.1 +/- 0.4- and 2.9 +/- 0.6-fold respectively in the presence of 0.5% serum. These results indicate that sequences responsible for insulin regulation of FAS gene are also located within 332 bp of the transcription start site.

3T3 Cells↗
PubMed1993

[Right ventricular endomyocardial biopsy from the femoral vein].

Several methods are used for percutaneous right ventricular endomyocardial biopsy, including the subclavian venous approach, internal jugular venous approach and femoral venous approach. The femoral venous approach is the most suitable for routine cardiac catheterization, but the risk of right bundle branch block may be increased because the specimens often must be taken from a high position in the right ventricle. We modified the femoral venous approach using King's biotome, and obtained adequate tissue specimens in 14 cases without any complications. We reformed the tip of the biotome into an inverted S shape by scrubbing with the thumb, and we reformed the tip of the long sheath (Cordis) into a J shape by warming with steam, for easy introduction of the biotome and safe biopsy. We describe here the methodological details of our technique.

Biopsy↗
PubMed1993

Increased expression of membrane-associated phospholipase A2 shows malignant potential of human breast cancer cells.

BACKGROUND: Recently, the authors reported that membrane-associated phospholipase A2 (M-PLA2) was one of the acute phase reactants and increased in serum of patients with various malignant tumors. METHODS: M-PLA2 concentrations in tissue specimens from 78 breast cancers, 16 benign breast tumors, and 10 normal breast tissues were determined by a specific radioimmunoassay recently developed. Immunohistochemical staining was performed on all specimens by the avidin-biotin-peroxidase method. RESULTS: Tissue levels of M-PLA2 concentration were significantly higher in breast cancer than in benign breast tumor or normal breast tissue (P < 0.01). Correlation analyses between the tissue concentration of M-PLA2 and clinicopathologic factors showed that tissue M-PLA2 levels were significantly higher in patients with skin or muscle invasion, vessel involvement, and distant metastasis than in those without. In addition, this enzyme concentration was significantly greater in scirrhous carcinoma than in papillotubular or solid-tubular carcinoma. No association was found between M-PLA2 concentration and steroid hormone receptor status. Immunohistochemically, M-PLA2 was preferentially stained in the invading zone of breast cancer tissues, especially in scirrhous carcinoma. Patients with breast cancer with low levels of M-PLA2 showed significantly longer overall survival and disease-free survival compared with those with high levels of this enzyme at the cutoff point of 50 ng/100 mg protein. The combination of estrogen receptor status with M-PLA2 concentration could be a powerful prognostic factor in predicting such survival rates. CONCLUSIONS: M-PLA2 is closely related to the malignant potential of breast cancers, and the M-PLA2 contents in breast cancer tissues could be a new valuable prognostic factor, other than the hormone receptor, in delineating the status of human breast cancer.

Breast↗
PubMed1993

Biological receptors mediate anti-proliferative action of atrial natriuretic peptide in cultured mesangial cells.

The mechanism of anti-proliferative action of atrial natriuretic peptide (ANP) was examined in cultured mesangial cells. HS-142-1, a selective antagonist for ANP biological receptors, inhibited ANP-induced cellular cGMP accumulation and prevented ANP-induced inhibition of both serum-stimulated incorporation of 3H-thymidine and cell proliferation. Des-[Gln18, Ser19, Gly20, Leu21, Gly22]-ANP4-23-NH2 (C-ANP) failed to inhibit 3H-thymidine incorporation. These results indicate that anti-proliferative action of ANP is mediated by the biological receptors in cultured mesangial cells.

Animals↗
PubMed1993

[Radiation therapy for superficial type esophageal carcinoma].

During the period from 1984 through 1991, fifteen patients with superficial esophageal carcinoma were treated with radiation therapy. The clinical stage of these patients was I in 13 cases and IV in two cases. We analyzed the treatment results of 13 patients with stage I disease. Seven patients were treated with external irradiation only and six patients with external irradiation plus high dose rate intracavitary irradiation. The survival rates at one, two and five years were 73.3%, 73.3% and 30.6%, respectively. The relapse-free survival rates at one, two and five years were 76.9%, 76.9% and 76.9%, respectively. Combination chemotherapy and combined therapy with intracavitary irradiation did not improve the local control rate or survival. At present, six patients have already died. The cause of death was uncontrolled primary lesion in one, radiation-induced esophageal ulcer in one, other causes in three and unknown cause in one patient. Local control was achieved in 84.6%(11/13). Radiation therapy for superficial esophageal carcinoma seems as effective as surgical therapy and may become a curative alternative.

Aged↗