PubMed Health⌕ Search

Biomedical subjects

N Nishimura

Publications and source records attributed to N Nishimura.

At least 127 records · Page 7Linked to original sources
PubMed1984

Changes of hemodynamics and O2 transport associated with the perfluorochemical blood substitute, Fluosol-DA.

Hemodynamic, arterial O2 tension (PaO2) and transcutaneous O2 tension (PtcO2) changes associated with the infusion of 500 ml of Fluosol-DA were evaluated in 14 decerebrated patients. Flow-directed pulmonary artery catheters and the Clark-type oxygen electrode manufactured by Hoffmann-La Roche were utilized. The marked improvement of cardiovascular variables along with marked increases in PaO2 and PtcO2 may indicate a marked increase in skin circulation by the infusion of Fluosol. One patient exhibited a hypotensive episode during the infusion, which lasted only a short time, disappeared spontaneously, and did not prohibit the further infusion of Fluosol. We still consider that Fluosol will be clinically useful for increasing oxygen capacity and improving overall hemodynamic status as well as individual organ circulation.

Adult↗
PubMed1984

Aspartase-hyperproducing mutants of Escherichia coli B.

When a wild-type strain of Escherichia coli B was cultured on a medium containing L-aspartic acid as the sole carbon source (Asp-C medium), aspartase formation was higher than that observed in minimal medium. Addition of glucose to Asp-C medium decreased aspartase formation. When also cultured in a medium containing L-aspartic acid as the sole nitrogen source (Asp-N medium), E. coli B showed a low level of aspartase formation and an elongated doubling time. To obtain aspartase-hyperproducing strains, we enriched cells growing faster than cells of the wild-type strain in Asp-N medium by continuous cultivation of mutagenized cells. After plate selection, the doubling times of these mutants were measured. Thereafter, fast-growing mutants were tested for aspartase formation. One of these mutants, strain EAPc7, had a higher level of aspartase formation than did the wild-type strain in medium containing L-aspartic acid as the carbon source, however; addition of glucose to this medium decreased aspartase formation. The other mutant, strain EAPc244, had a higher level of aspartase activity than did the wild-type strain in both media. Therefore, aspartase formation in mutant EAPc244 was released from catabolite repression. In strain EAPc244 the other catabolite-repressible enzymes, beta-galactosidase, tryptophanase, and the three tricarboxylic acid cycle enzymes, were also released from catabolite repression. Both mutants had sevenfold the aspartase formation of the wild-type strain in a medium which contained fumaric acid as the main carbon source and which has been used for industrial production of E. coli B aspartase. However, strain EAPc244 had 2.5-fold the fumarase activity of strain EAPc7.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia-Lyases↗
PubMed1984

A new method for external fixation with single crystal alumina ceramic screw nail and its biomechanical study.

Through the use of the Hoffmann external fixator, we have recognized the importance of strength of fixation between the screw nail and the bone in the external fixation and have fully realized the necessity of an affinity of the screw nail to the soft tissue at the thrusting site of the screw nail. We made a screw nail for external fixation with single crystal alumina ceramic on an experimental basis and after its basic test of strength, tried its clinical application by the Hoffmann external fixator. When this screw nail was used, it was found difficult to fix the screw nails thrusted in each different direction by the Hoffmann external fixator because of the small elasticity of the sapphire screw nail itself. However when the screw nails were fixed by force, a great stress concentration occurred in them or the bone around them and this caused their breakage and loosening. To protect this, we have developed a new external fixator which enables to hold, connect and fix each screw nail at the individual thrusting positions and directions and is therefore completely universal to each plane.

Adult↗
PubMed1984

[Serial strain gauge measurement of bone healing in Hoffmann external fixation].

Since 1978, the author has applied Hoffmann external fixation to the treatment of open fractures and infected pseudoarthrosis of long bones in the lower limbs, but has some difficulties in determining when weight bearing should be started after operation, how much weight bearing should be and when the pin should be removed. As new method to mechanically analyze the callus strength, I tried to estimate the amount of strain at intervals of 2 to 3 weeks, beginning from the second week after operation, by bending or compressing the fracture site through the strain gauge glued to the middle of the external fixator's connecting rod. From a strength test by means of a model of fracture using a vinyl chloride pipe and also from a study of computer calculation using the model of plane beam structure for architectural design, it was found that the amount of the strain on the connecting rod decreased hyperbolically when the mechanical properties of the callus increased, and that it became constant when the mechanical properties of the callus reached 50% of the intact bone. The strength test using an cadaveric skin bone demonstrated that the callus volume was one of the most important and affecting factor. Twenty-three cases were treated by Hoffmann external fixation, and the bone healing was achieved in 20 of them. On the basis of the bone healing curve obtained by the serial strain gauge measurement in those cases, the bone healing process could be classified into 5 types: normal healing, slow healing, non-union, arrest in evolution and breakage of callus; and were employed as indexes in the post-operative rehabilitation program.

Adolescent↗
PubMed1983

Immunoreactive thyroid stimulating hormone (TSH)(: association with synaptosomally-rich fractions in the rat hypothalamus.

The subcellular compartmentalization of brain thyroid stimulating hormone (TSH) in the hypothalamus of the rat was investigated using differential and discontinuous sucrose density gradient centrifugation. When the mitochondrial fraction (P2) was layered on a discontinuous sucrose density gradient (0.32-1.4 M) and centrifuged for 60 min at 72,000 g, TSH recovered from the gradient was found, by double antibody radioimmunoassay, to be associated preferentially with the synaptosomally-rich layers. The separation was monitored by electron microscopic examination of all fractions obtained throughout the procedure. The addition of a large excess of either [125I]-labeled or unlabeled pituitary TSH at the time of homogenization did not influence the amount of immunoreactive TSH associated with the synaptosome-rich fractions, and both the unlabeled and labeled hormone were recoverable in the final supernatant indicating that the simple addition of peptide to hypothalamic homogenates did not result in any preferential association to any particular subcellular fraction. The apparent association of this brain-based pituitary peptide was not, therefore, an artifact of the homogenization process. It is concluded that an association exists between immunoassayable TSH and brain-based synaptosomes in homogenates of the rodent hypothalamus.

Animals↗
PubMed1983

Changes of lung water and cardiovascular parameters during neurosurgical procedures associated with various types of infusion.

With the Swan-Ganz catheter and double indicator technique cardiovascular parameters and lung water were measured in 16 neurosurgical procedures. Five hundred millilitres of whole blood, Manitol or Fluosol-DA, or 1000 ml of lactate-Ringer solution was infused within 30 min, and various parameters were estimated and analysed. Extravascular lung water did not change with either solutions. Fluosol-DA showed the most powerful pressure effects. With whole blood and Fluosol DA, cardiac output and oxygen availability increased. Marked hemodilution was observed with the infusion of either Manitol, Fluosol-DA or lactate-Ringer solution, but only Fluosol-DA insured adequate oxygen supply to tissues by increase in oxygen capacity in blood. Fluosol-DA proved to be one of the suitable colloidal solutions to improve the hemodynamics and hemodilution during operation.

Adult↗
PubMed1983

Zearalenone reductase from rat liver.

Zearalenone is known to be reduced by rat liver preparations to a more active estrogenic metabolite, alpha-zearalenol. To elucidate the enzymatic feature of zearalenone reductase, we worked out a simple assay procedure for this enzyme using [3H]-zearalenone and thin layer chromatography (TLC). The NAD(P)H-dependent zearalenone reductase localized in the microsomes was most active at pH 4-4.5, while the reductase localized in the cytosol was active at neutral pH. The former enzyme reduced zearalenone only to alpha-zearalenol and the latter reduced both alpha-zearalenol and beta-zearalenol. The microsomal enzyme was solubilized with Triton X-100 and purified by DEAE-Sephadex, hydroxyapatite and Sepharose 4B column chromatographies. The partially purified enzyme showed the following properties. a) The molecular weight of the enzyme was estimated to be about 230,000 by Sepharose 4B chromatography. b) The apparent Km value of the enzyme was 1.0 X 10(-5) M for zearalenone at an NADPH concentration of 1 mM. c) The enzyme activity was inhibited by a high concentration of KCl but not by 1 mM Co2+, Mn2+, Zn2+, EDTA, or 20 mM N-ethylmaleimide.

Alcohol Oxidoreductases↗
PubMed1983

Cardiovascular effects of various colloidal solutions during major abdominal surgery.

We examined the effects of various colloidal solutions on cardiovascular and oxygen transport variables for 26 patients undergoing gastrectomy under general anesthesia. Fluosol-DA, whole blood, 3% Dextran-40 (Saviosol), and 6% hydroxyethyl starch (hetastarch, Hespan) affected the right side of heart, but only whole blood and Fluosol-DA significantly increased cardiac output and oxygen delivery (DO2). Fluosol-DA may prove useful for critical care of hemorrhagic shock during operation or resuscitation in the immediate postoperative period.

Adult↗
PubMed1983

Alterations of gastrin secretion in obese rats with ventromedial hypothalamic lesions.

Basal plasma gastrin levels were significantly higher in obese rats induced by ventromedial hypothalamic lesions (VMH rats) than in sham-operated controls. Gastrin secretion in response to insulin hypoglycemia and a liquid diet load was higher in VMH rats than in controls. The antral gastrin concentration was also elevated in VMH rats. Pair-fed rats with VMH lesions showed increased gastrin secretion as did the non-pair-fed group. These results show that gastrointestinal hormone secretions as well as pancreatic endocrine function are abnormal in obese rats with VMH lesions. Increased gastrin secretion is probably induced by factors other then hyperphagia, such as disturbance of the autonomic nervous system due to the VMH lesions.

Animals↗
PubMed1983

The effect of Fluosol-DA on pulmonary vessels.

The infusion of Fluosol-DA will increase the pulmonary artery pressure and the capillary wedge pressure as well as increase the cardiac output. The changes were more marked with the infusion of Fluosol-DA compared to whole blood, Hespander, or Saviosol. Calculated pulmonary vascular resistance decreased with Fluosol-DA infusion and lung water did not increase. We reconfirmed that during infusion of Fluosol-DA, PaO2 increased in many cases and the calculated shunt ratio decreased as a result.

Adult↗