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Biomedical subjects

Y Sakamoto

Publications and source records attributed to Y Sakamoto.

At least 433 records · Page 24Linked to original sources
PubMed1991

Bovine leukemia virus matrix-associated protein MA(p15): further processing and formation of a specific complex with the dimer of the 5'-terminal genomic RNA fragment.

The retrovirus precursor protein has an arrangement of several characteristic domains with which it achieves selective and efficient packaging of the genome RNA during particle assembly. In this study, we analyzed the composition of the bovine leukemia virus (BLV) gag proteins and examined their RNA-binding properties in gel mobility shift assays, using various genomic RNA probes synthesized in vitro. Results obtained in amino acid sequence and composition analyses indicate that the matrix-associated protein MA(p15) is further processed by the BLV protease (PR) to generate MA(p10), a short peptide of seven amino acid residues, and p4. The gag precursor is now mapped as NH2-MA(p10)-p4-CA(p24)-NC(p12)-COOH. MA(p15) formed a specific complex with the dimer RNA of the U5-5' gag region presumed to contain the BLV packaging signal but not with other RNAs. The NH2-terminal cleavage product, MA(p10), bound all RNA fragments tested, while the COOH-terminal peptides with a sequence common to mammalian type C retroviruses had little affinity for RNA. The nucleocapsid protein NC(p12) bound to RNAs nonspecifically and randomly in the presence or absence of zinc ions. These results suggest a possible interaction of the NH2 terminus of the gag precursor with the 5' terminus of the genomic RNA in an early phase of particle assembly, when the conserved structure between the MA and CA domains might be involved.

Amino Acid Sequence↗
PubMed1991

Normal and abnormal pituitary glands: gadopentetate dimeglumine-enhanced MR imaging.

Dynamic magnetic resonance (MR) imaging with a 1.5-T superconductive unit was used in the evaluation of nine normal pituitary glands and 10 pituitary adenomas, including four microadenomas and six macroadenomas. Seven to 10 images were obtained every 20-30 seconds with use of the spin-echo technique after rapid injection of gadopentetate dimeglumine. The earliest contrast material enhancement of normal structures was seen in the infundibulum and posterior lobe of the pituitary gland at 20 seconds, followed by gradual contrast material enhancement of the anterior lobe of the pituitary gland from the junction of the infundibulum to the peripheral portion of the anterior lobe of the pituitary gland within 80 seconds after gadopentetate dimeglumine injection. The peak enhancement of pituitary adenomas occurred at 60-200 seconds, usually after the most marked enhancement of the normal pituitary gland. Microadenomas are best visualized at earlier phases of gadopentetate dimeglumine-enhanced dynamic imaging, with signal intensity lower than that seen on images of normal pituitary glands.

Adenoma↗
PubMed1991

Cavernous sinus: correlation between anatomic and dynamic gadolinium-enhanced MR imaging findings.

Dynamic magnetic resonance (MR) images were evaluated and compared with conventional T1-weighted spin-echo (SE) images obtained before and after administration of gadopentetate dimeglumine in 20 patients with normal cavernous sinuses. Starting 10 seconds after rapid injection of gadopentetate dimeglumine (0.1 mmol/kg), six to eight serial images were obtained every 30 seconds for 3-5 minutes. The venous spaces of the cavernous sinus were markedly enhanced 30 seconds after injection. Cranial nerves III and IV, V1 and VI, and V2 were seen on 75% of dynamic images each; they were seen, respectively, on 62%, 30%, and 28% of conventional postcontrast images. The medial wall was demarcated on 90% of dynamic, 15% of precontrast, and 55% of postcontrast images. A small area of connective tissue was identified within the cavernous sinus on dynamic images showing gradual enhancement. It is concluded that dynamic MR images proved useful in delineating and distinguishing abnormal tissue from normal structures.

Cavernous Sinus↗
PubMed1991

Electron microscopy of histamine-induced contraction of the in vitro swine coronary artery.

Dose-dependent contractions of the in vitro swine coronary artery were induced by application of histamine and acetylcholine, but not of angiotensin II, ergonovine, noradrenaline, prostaglandin F2 alpha and serotonin. Ultrastructural changes especially of the tunica intima during the contractions were observed at 2, 5 and 30 min after application of histamine and acetylcholine. The intimal gutter spirally running along the longitudinal axis of the vessel was obscured, and the intimal surface became extensively indented. Exclusively in the histamine-treated samples, the increase in number and size of the intracellular vacuoles and the dilation of the intercellular clefts to the extent of the intercellular vacuoles were observed in the endothelium. Moreover, the enhancement of the endothelial permeability was indicated by the marker experiments using horseradish peroxidase. Such endothelial cell damages and the enhancement of the endothelial permeability may amplify the coronary artery contraction.

Acetylcholine↗
PubMed1991

Acute spinal cord injury: magnetic resonance imaging correlated with myelopathy.

Thirty-one patients (29 males and two females, 13-87 years of age (mean, 46.7 years] with acute spinal cord injury were studied by MR (magnetic resonance) imaging and the results were correlated with neurological findings. Magnetic resonance images were obtained with a 0.5 T superconductive MR scanner (Phillips Gyroscan S5). Initial imaging was performed within 24 hours after trauma in 13 patients, 1-7 days in 13 patients and 7-14 days in five patients. Twenty-six patients underwent follow-up examinations with MR imaging. Cord abnormalities including cord compression (23 patients), cord swelling (seven patients), and abnormal signal intensities on either T1 or T2-weighted images (26 patients) were observed on initial examination. Multivariate analysis showed that cord compression and abnormal intensities on T1-weighted images were important prognostic indicators. Hyperintensity on T2-weighted images was non-specific but correlated well with clinical recovery. Magnetic resonance imaging is useful in predicting the prognosis and for planning treatment following spinal cord injuries.

Acute Disease↗
PubMed1991

[The influence of repirinast, an anti-allergic drug, on theophylline pharmacokinetics in patients with bronchial asthma].

In order to clarify whether repirinast, an inhibitor of chemical mediator release, could influence the pharmacokinetics of theophylline, a loading test using intravenous injection of aminophylline was performed in 10 subjects with bronchial asthma before and after treatment with 300 mg/day of repirinast. There was no significant difference in theophylline half-life before treatment (7.25 +/- 2.43 hr) and after treatment (7.82 +/- 3.35 hr). There was no significant difference in theophylline clearance before treatment (0.047 +/- 0.018 L/kg/hr) and after treatment (0.047 +/- 0.020 L/kg/hr). These results demonstrated that repirinast does not modify theophylline pharmacokinetics significantly.

Adult↗
PubMed1991

[Correlations between redistribution areas observed on exercise thallium-201 myocardial SPECT images and the coronary collateral circulations in patients with myocardial infarction].

The significance of coronary collateral circulation for redistribution in the infarcted zone was evaluated in 16 patients with history of myocardial infarction and severe stenosis (> or = 90%) of the coronary artery. Redistribution areas were quantitatively measured using the redistribution ratios and redistribution indices on the infarction-redistribution map obtained by thallium-201 scintigraphy with single photon emission computed tomography. Coronary collateral findings were categorized in 4 classes according to the Rentrop's grading. There was good, positive linear correlation between the redistribution ratio (Y) and collateral grading (X) (Y = 0.21X + 0.10, r = 0.92, p < 0.01). The redistribution index (X) also correlated well with the collateral grading (Y) using a good, positive quadratic equation (Y = 0.32X2 + 0.24X + 0.04, r = 0.89, p < 0.01). These results suggest that the measurements of the redistribution areas in the ischemic zone in myocardial infarction correlated well with collateral perfusion. Collateral perfusion severer than Rentrop's grade 2 markedly reduces the severity of ischemia and increases redistribution areas.

Collateral Circulation↗
PubMed1991

[Predictability of preclinical evaluation of anticancer drugs by human gastrointestinal cancer--nude mouse panel].

We evaluated the predictability to clinical response of experimental effects of various anticancer agents on human cancer--nude mouse panel established in our department. The human cancer lines used were 12 gastric, 4 colorectal, 3 breast, 2 pancreatic cancers and 1 melanoma xenografted into BALB/c athymic nude mice under SPF conditions. Seven mice each with equivalent mean volume of sc inoculated tumor (about 100 mm3) were subjected to the treatment and control groups. Experimental treatment was conducted daily 25 times for antimetabolites, and intermittently 5 times once or twice a week for other drugs. Dosage of each drug adopted was maximal tolerated dose predetermined for the treatment schedule. Four weeks after the initiation of treatment, the therapeutic effect of each experiment was evaluated by the tumor growth inhibition rate (IR) based on the comparison of mean tumor weight between the 2 groups. When the IR was greater than 58%, the drug was evaluated as effective. The clinical response rate of each drug was referred from the result of the phase II study. Direct comparison of effects on 16 experimental chemotherapies in xenografts with responses to the corresponding clinical therapy of each donor patient revealed a fairly high accordance rate (94%). To elucidate the value of human cancer--nude mouse panel as the preclinical secondary screening, the response rates of 8 anticancer drugs treated to 15 cancer xenografts were compared with the cumulative clinical data available in each drug. Generally, the response rates of the human cancer xenografts to the drugs showed fairly good correlations with the cumulative clinical response rates of the corresponding drugs to the same organs. Using this panel, preclinical examinations of 6 new agents under development, including 254 S and other 2 CDDP derivatives, were performed in expectation the positive correlation with further clinical data.

Animals↗
PubMed1991

[Blood biochemistry during acidosis associated with ATP-induced hypotensive anesthesia].

Several investigators reported metabolic acidosis during ATP-induced hypotensive anesthesia. To elucidate the etiology, we studied blood biochemistry during hypotensive anesthesia for tympanoplastic surgery. The blood concentration of lactic acid, uric acid, phosphoric acid and carbonic acid increased and their total amount coincided with the base excess change. We also found that metabolic intermediates of glycolysis and of the catabolic pathway of adenosine also increased proportionally. The result suggests that the metabolic change is caused by lactic acid produced from glycolysis promoted by ATP and by the catabolic products of administered ATP itself.

Acidosis↗
PubMed1991

[Bronchial lavage in the treatment of status asthmaticus].

Bronchial lavage was performed in 10 cases with status asthmaticus who were mechanically ventilated. The mean value of PaCO2 was 64.4 +/- 17.4 Torr before bronchial lavage, and it significantly decreased to 51.9 +/- 11.0 Torr after lavage. In 7 out the 10 cases, bronchial lavage was judged to be effective from the clinical point of view. In 5 cases with values of PaCO2 of over 55 Torr before lavage, massive mucus plugs were recovered. Bronchial lavage was judged to be effective in all of them, whereas three out of the another five cases whose values of PaCO2 were less than 55 Torr showed exacerbation of hypercapnia, and the state of asthma worsened and/or continued for a longer period. The ratio of PaO2/FiO2 did not improve even in effective cases. These results indicated that bronchial lavage is a useful tool to improve the hypercapnic state in patient with status asthmaticus being mechanically ventilated, if the value of PaCO2 is over 55 Torr.

Adult↗
PubMed1991

[Factors relating to postoperative infections in cancer patients].

Some factors relating to the increasing prevalence of postoperative infections after gastroenterological surgery were investigated from the standpoint of both patients profile and isolated bacteria. Data were collected from 542 cancer patients comprising 39 with esophagus cancer, 229 with gastric cancer, 149 with hepato-biliary tract and pancreatic cancer and 125 with colon cancer. Respiratory infections after operations were most frequently caused by aging, disturbance of glucose tolerance and respiratory dysfunction, whereas with intraabdominal abscess the major factors were disturbance of glucose tolerance, hepatic dysfunction and respiratory dysfunction in this order. Two factors in the management of patients during operation were singled out as mainly contributing to infection: these were prolonged operative time as in the case of esophagus cancer or hepato-biliary tract and pancreatic cancer, and massive intraoperative bleeding as in hepato-biliary tract, pancreatic and gastric cancer. As isolated bacteria, the most frequent clinical isolates were MRSA, Enterococcus, P. aeruginosa and Enterobacter, and it is noteworthy that all of these were strongly resistant to all antimicrobial agents. The greater emphasis on prevention control of postoperative infections, therefore, should be focussed on aging, preoperative risk factors, surgical stress and the kinds of antimicrobial agents administered.

Bacterial Infections↗
PubMed1991

[New developments of neuro-imaging].

Magnetic resonance imaging has contributed significantly in the recent development of neuro-imaging, especially in recent advances of neuroimaging of brain tumors. MR imaging has numerous advantages over CT such as excellent contrast resolution, arbitrary imaging planes, no bone artifacts and no radiation. Further clinical potential of MR imaging includes fast imaging with use of gradient echo technique, 3 dimensional imaging by 3 DFT and MR angiography. These new techniques will contribute significantly to the advancements of neuroimaging in the near future.

Adult↗
PubMed1991

[Left ventricular cardiomyoplasty by the use of a free latissimus dorsi myograft with a vascular anastomosis--augmentation of regional cardiac performance in dyskinetic segments].

This study was performed to evaluate the ability of a free revascularized Latissimus Dorsi (LD) graft placed on dyskinetic segments of the left ventricle to augment regional left ventricular performance in 8 adult dogs. LD muscles preconditioned for 30 days were revascularized with the internal mammary artery and right atrial appendage. The free graft was sutured on the ischemic area of the left ventricular anterolateral wall, produced by ligation of the left anterior descending coronary artery. Grafts were paced at a burst frequency of 25 and 50 Hz, at a synchronization ratio of 1:1, 2:1, and 3:1. Effects of synchronously paced LD grafts on regional myocardial performance and hemodynamics were evaluated by placing ultrasonic crystals on the ischemic area and hemodynamic parameters. The flow rate of revascularized thoracodorsal artery (TDA flow) was measured during synchronously pacing of the grafts. Systolic bulging was shown in the ischemic area without graft pacing: %shortening (%S) = -9.5 +/- 3.6%. Graft pacing at a burst frequency of 25 and 50 Hz resulted passive segmental shortening of the ischemic left ventricular myocardium: %S = +3.9 +/- 1.9% (p less than 0.01, vs values without pacing) and +5.5 +/- 1.9% (p less than 0.01, vs values without pacing), respectively. The left ventricular pressure increased from 74 +/- 14 mmHg to 83 +/- 15 mmHg (p less than 0.01) with graft pacing at a burst frequency of 50 Hz. The peak aortic flow also was augmented by an average of 30 +/- 6% at paced cardiac cycles. The pattern of TDA flow during 1:1 synchronous pacing was changed to be dominant in diastolic, unlike the pattern without graft pacing. Values of TDA flow rate, however, increased after the initiation of pacing and reached 270 +/- 38% of control values. In conclusions, this study shows that a revascularized free LD graft has an ability to contract in systole against the left ventricular wall stress, and to augment regional left ventricular performance in dyskinetic segments. And sufficient blood perfusion to the grafts can be maintained during synchronously pacing of the grafts in cardiac systole.

Animals↗
PubMed1991

[Experimental study on potential for cardiac assist by latissimus dorsi myograft--an importance of muscle ischemia].

We have studied contractile property and fatigue rates of skeletal muscle ventricle (SMV) constructed using the latissimus dorsi muscles of 11 dogs. The role of early interruption of collateral blood supply in the prevention of muscle ischemia and SMV fatigue was evaluated. Systolic function of SMV was measured in a hydraulic test system; afterload was set at 70 mmHg and preload 15 or 25 mmHg. Control SMV (GI: N = 7), which was fashioned immediately after interruption of collateral blood supply, generated an initial SMV pressure of 222 +/- 50 mmHg and stroke volume of 15 +/- 7 ml/beat with muscle stimulation at a burst-frequency of 50 Hz, but could sustain flow for only 3.5 +/- 0.8 minutes. SMV subjected to a vascular delay (Group II: N = 4) demonstrated improvement of fatigue rates; duration of flow 32.4 +/- 14.0 and sufficient contractile property (initial SMV pressure 182 +/- 17 mmHg, stroke volume 1- +/- 2 ml/beat). Thermography surface temperature mapping revealed remarkable improvement of blood distribution in GII muscles. Flow rates of thoracodorsal artery were significantly greater in GII muscles compared to those in GI muscles (15.0 +/- 3.7 ml/min/LD 100 g, 10.1 +/- 3.1 ml/min/LD 100 g, p less than 0.05, respectively). Despite significant improvement of functional durability in GII muscles, the ratio of oxygen consumption to lactate output was not different between 2 groups. These results suggest that early interruption of collateral blood supply can minimize muscle ischemia, resulting in diminishing fatigue of latissimus dorsi muscles without changes in skeletal muscle metabolism.

Animals↗
PubMed1991

[Potential for left ventricular assistance by latissimus dorsi myograft--sequential effects of electrical preconditioning on skeletal muscle fiber type, blood flow and metabolic status].

In order to evaluate the possibility of left ventricular assistance by latissimus dorsi (LD) myograft, we have studied contractile property and fatigue rates of skeletal muscle ventricle (SMV) constructed using canine LD muscles. Twenty three dogs were divided into 3 groups depending on the conditioning protocol of LD muscles; Group I (Control n = 12), Group II (Vascular delay n = 4) and Group III (Vascular delay and electrical preconditioning n = 7). SMVs in GIII dogs generated sufficient pressure and forward flow in a hydraulic test system with muscle stimulation at a burst-frequency of 50 Hz (SMV pressure 131 +/- 42 mmHg, Stroke volume 7.0 +/- 3.0 ml/beat). Although SMVs in GI and GII dogs could sustain flow for only 4.0 +/- 1.1 minutes and 32.4 +/- 14.0 minutes, respectively, SMVs in GIII were able to pump continuously for 107.5 +/- 15.0 minutes (p less than 0.01, vs GI and GII). Thermography surface temperature mapping revealed marked improvement of blood distribution of LD muscles in GII and GIII dogs. Flow rates of thoracodorsal artery during SMV stimulation were GI: 10.0 +/- 3.1 ml/minute/LD 100 g, GII: 15.0 +/- 3.7 ml/minutes/100 g and GIII: 20.7 +/- 2.5 ml/minutes/100 g (p less than 0.01 vs GI). The ratio of oxygen consumption to lactate output was GI: 0.33 +/- 0.10, GII: 0.36 +/- 0.09 and GIII: 1.56 +/- 0.97 (p less than 0.01 vs GI, p less than 0.05 vs GII). Histochemical examination of LD muscles using alkaline ATPase stain revealed muscle fiber type transformation of GIII muscles. These results suggest electrically preconditioned LD muscles have sufficient contractile property for partial left ventricular assistance, and highly fatigue-resistant properties resulted from muscle fiber transformation, improved muscle perfusion and metabolic changes.

Animals↗
PubMed1991

[An operated case report of pulmonary aspergillosis by sapprophytic infection of Aspergillus candidus in congenital bronchial cyst of right lower lobe].

Aspergillosis is a mycotic disease caused by a variety of species of the dimorphic fungus aspergillosis, especially aspergillus fumigatus. But the report of pulmonary aspergillosis by aspergillus candidus is very rare. We experienced a surgical case of pulmonary aspergillosis caused by aspergillus candidus. The patient is a 18-year-old girl. Eleven years ago, she had suffered from pneumonia of rt. lower lobe, there after she often has suffered from cough and fever every year. In 1986, chest x-ray photography shows a small cavity in rt. lower lobe. In 1989, it becomes a big cavity of 8 X 8 cm in diameter with niveau. She has cough and bloody sputum of 100-150 ml daily. We have cultured aspergillus candidus from sputum, bloody pus obtained by percutaneous aspiration needle lung biopsy of the cavity and bloody pus in the cavity which was resected on March 3, 1989. But the pathological investigation could not demonstrate any fungus ball or fungus body of aspergillus candidus.

Adolescent↗