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Biomedical subjects

T Asano

Publications and source records attributed to T Asano.

At least 757 records · Page 42Linked to original sources
PubMed1986

The effects of mandibular retractive force on the growing rat mandible.

The purpose of this study was to investigate the three-dimensional effects of a mandibular retractive force on the growing rat mandible and mandibular growth after the force was removed. Eighty 4-week-old male Wistar rats served as experimental animals and 100 4-week-old male Wistar rats served as the control group. The experimental rats were divided into four groups. Thirty grams of retractive force was applied to each mandible for 4 weeks. Each group was then killed after 4-, 8-, 10-, 12-, or 16-week periods. At the time of death, tibia, skull, and mandible were removed, measurements of those bone specimens were taken, and histologic examinations were performed. Compared with the control group, the experimental group demonstrated no significant differences in body weight nor in the length of measurements of the tibia, skull, and proximal end of the tibia. The mandibles of the experimental group demonstrated shorter anteroposterior length, higher coronoid processes, and a thicker corpus in the retromolar region and condylar neck. The condylar cartilages of the experimental group showed moderate adaptation in the histologic sections. However, mandibles of the experimental animals did not show any catch-up growth behavior after removal of the force. It was concluded that the mandibular retractive force could produce overall growth retardation and transformation of growing rat mandibles, but the force had no effect on the growth behavior after the appliance was removed.

Animals↗
PubMed1986

Electrophysiologic effects of surgical isolation of the right ventricle.

Surgical isolation of the entire right ventricular free-wall was performed in ten dogs to evaluate the effects of the procedure on a variety of electrophysiologic measurements. Complete surgical isolation of the right ventricle was confirmed by determining that right ventricular electrical activity was not conducted to the remainder of the heart and that electrical activity in the atria or left ventricle did not conduct to the right ventricle. Right ventricular isolation caused no change in right ventricular or left ventricular pacing thresholds, in effective refractory periods of the right ventricle or left ventricle, or in right ventricular free-wall conduction time. Moreover, the normal conduction time from the right atrium to the left ventricle was 139 +/- 5 msec (mean +/- standard error) preoperatively and 135 +/- 5 msec postoperatively (p is not significant), showing that atrial-to-left ventricular synchrony was unaltered by isolation of the right ventricle. However, following isolation, the right ventricle could not be electrically fibrillated in 9 of 10 animals, a finding that may have important implications in the future development of surgical procedures to control chronic, life-threatening ventricular tachyarrhythmias.

Animals↗
PubMed1986

Enhancement of ATPase activity by a lipid peroxide of arachidonic acid in rat brain microvessels.

The effects of 15-hydroperoxyarachidonic acid (15-HPAA) on Na+, K+- and Mg+-ATPase activities in the blood-brain barrier (BBB) were examined using rat brain microvessels (MV). 15-HPAA markedly stimulated these ATPase activities in MV at low concentrations whereas the synaptosomal Na+, K+-ATPase activity was inhibited in a dose-dependent manner. Further neurochemical analysis revealed that this stimulatory effect of 15-HPAA in MV was not due to a simple detergent-like action of the compound on the membranes but rather to stimulation of the phospholipase A2 and lipoxygenase activity within MV. In addition, it was shown that free radical reactions were involved in the mechanism. Since such anti-edema drugs as 1,2-bis(nicotinamido)propane were proved to be potent suppressors of the enhanced ATPase activity, further speculations on the role of this effect for ischemic brain edema are offered.

Adenosine Triphosphatases↗
PubMed1986

Hypodipsic hypernatremia associated with absence of septum lucidum and olfactory dysfunction.

A case of hypodipsic hypernatremia in a 16-month-old Japanese boy is reported. Partial antidiuretic hormone deficiency was present. Computed tomography of the brain revealed absence of septum lucidum. No ophthalmological abnormality could be found. He had hyposmia, which has not been reported previously in association with hypernatremia due to hypodipsia. Forced fluid administration and nasal 1-deamino-8-d-arginine vasopressin treatment could maintain serum electrolyte levels within normal ranges. However, episodes of hypernatremia could not be completely avoided while he was treated with 1-deamino-8-d-arginine vasopressin and ad libitum oral fluid.

Central Nervous System↗
PubMed1986

The effect of chemical ablation of the endocardium on ventricular fibrillation threshold.

The purpose of this study was to examine the effects of ablation of the superficial endocardium and Purkinje network on left ventricular fibrillation threshold. Lugol's solution was applied through small ventriculotomies to the left and right ventricular endocardium of 10 dogs on cardiopulmonary bypass. Two control groups of five animals each underwent either endocardial application of saline or epicardial application of Lugol's solution. Ventricular fibrillation threshold was measured before and after each intervention by the single-stimulus technique. Application of Lugol's solution to the endocardium resulted in a 102 +/- 15% increase in ventricular fibrillation threshold from a control value of 26 +/- 2 to 53 +/- 6 mA (p less than .005). In two animals, ventricular fibrillation could not be initiated postoperatively. In the control groups, there were no significant changes in ventricular fibrillation threshold. Histologic examination revealed that Lugol's solution obliterated less than 0.5 mm of superficial endocardium while sparing the adjacent myocardium. Electrophysiologic and rheologic data confirmed the discrete nature of the chemical injury. Thus ablation of the superficial ventricular endocardium with Lugol's solution results in a profound increase in the ventricular fibrillation threshold with only minimal tissue destruction.

Animals↗
PubMed1986

The effects of HA compound calcium antagonists on delayed cerebral vasospasm in dogs.

The authors have examined the effects of the HA compounds HA1004(N-(2-guanidinoethyl)-5-isoquinolinesulfonamide) and HA 1077(1-(5-isoquinolinesulfonyl)homopiperazine), which are intracellular calcium antagonists, on delayed cerebral vasospasm from subarachnoid hemorrhage (SAH). The modes of action of these compounds were compared with those of the more commonly used calcium entry blockers. Calcium ionophore A23187 (4.8 X 10(-6) M)-induced contraction of a canine basilar artery strip was completely antagonized by the HA compounds (10(-5) M) but not by the entry-blocking calcium antagonists nicardipine, diltiazem, and verapamil (10(-5) M), suggesting that the HA compounds act differently. Delayed cerebral vasospasm was induced by a "two-hemorrhage" canine model. The magnitude of the vasospasm and the effects of the HA compounds were determined angiographically. On SAH Day 7, a significant vasospasm was observed in every dog. The diameter of the basilar artery had diminished to 59% +/- 2% (mean +/- standard error) of the control value obtained before SAH (on Day 1). The intravenous administration of HA 1004 caused a mild dilation of the basilar artery of 10% and 11% at doses of 3 and 10 mg/kg, respectively; however, HA 1077 produced a more marked dilation of 19% and 27%, respectively, at the same doses. Both of these drugs lowered mean arterial blood pressure to about 80% and 50% at doses of 3 and 10 mg/kg, respectively. Intracisternal administration of the HA compounds (6 mg) completely reversed cerebral vasospasm without much effect on the blood pressure. The intracellular calcium antagonists of the HA compound group appear to be promising agents for the treatment of intractable cerebral vasospasm.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1986

Uncoupling of gamma-aminobutyric acid B receptors from GTP-binding proteins by N-ethylmaleimide: effect of N-ethylmaleimide on purified GTP-binding proteins.

Treatment of membranes from bovine cerebral cortex with N-ethylmaleimide (NEM) resulted in inhibition of gamma-aminobutyric acid (GABA) binding to GABAB receptors. The binding curve for increasing concentrations of agonist was shifted to the right by NEM treatment. Guanine nucleotide had little effect on the binding of GABA to NEM-treated membranes. The addition of purified GTP-binding proteins, which were the substrates of islet-activating protein (IAP), pertussis toxin, to the NEM-treated membranes caused a shift of the binding curve to the left, suggesting modification of GTP-binding proteins rather than receptors by NEM. Therefore, the effect of NEM on two purified GTP-binding proteins, Gi (composed of three subunits with molecular weight of alpha, 41,000; beta, 35,000; gamma, 10,000) and Go (alpha, 39,000; beta, 35,000; gamma, 10,000) was studied. NEM did not significantly change guanosine 5'-(3-O-thio)triphosphate (GTP gamma S) binding and GTPase activity of these two proteins. In contrast, NEM-treated Gi and Go were not ADP-ribosylated by IAP and did not increase GABA binding to NEM-treated membranes. When alpha and beta gamma subunits were treated with NEM and then mixed with nontreated alpha and beta gamma to form Gi or Go, respectively, both oligomers with NEM-treated alpha-subunits lost their abilities to be IAP substrates and to couple to receptors. These results indicate that NEM uncoupled GTP-binding proteins from receptors by modifying alpha-subunits of GTP-binding proteins, and the site seemed to be on or near the site of ADP-ribosylation by IAP. When alpha and beta gamma subunits were treated with NEM and then mixed to form Gi or Go, GTP gamma S binding in the absence of Mg2+ and GTPase activity were changed, although they were not affected when oligomers were treated with NEM. The results suggest the existence of another sulfhydryl group which is protected from NEM by the association of subunits. The modification of this sulfhydryl group by NEM appeared to interfere with the interaction between alpha and beta gamma.

Adenosine Diphosphate Ribose↗
PubMed1986

[Autocrine growth factor produced by a human promyelocytic leukemia cell line].

Recently, a number of novel growth factors have been identified in culture medium conditioned by tumor cell lines. It is tempting to speculate that these growth factors produced by tumor cells could act as very good tumor markers. We have found that the conditioned medium of human promyelocytic leukemia cells (HL-60) stimulated [3H] glucose incorporation into lipids in rat adipocytes. When the conditioned medium was subjected to gel filtration on a Sephadex G-100 column, this activity was eluted in the fraction corresponding to a molecular weight of 10-12 K daltons. The production of this factor was maximal in the early log phase of cell growth and declined with increasing cell density. Differentiation of HL-60 cells to macrophages was also associated with a decrease in the production of this factor. This factor also stimulated [3H] thymidine uptake into DNA and cell proliferation in HL-60 cells themselves. These data suggest the possibility of autocrine growth of HL-60 as a result of this factor. We have subsequently tried to purify this factor. Two liters of serum-free conditioned HL-60 medium were used as a starting material. The material was purified by gel filtration, ion-exchange chromatography and high-performance liquid chromatography. Finally, 1.1 microgram of purified sample was obtained. The degree of purification was 115,613-fold. Growth factors can be very good tumor markers because this is the only tumor marker which has now been clarified to have an important role in tumor growth.

Cells, Cultured↗
PubMed1986

[A multi-center trial of MY-1, a new biological response modifier, on the immunological parameters of postoperative gastric cancer patients].

A multi-center study was performed to clarify the immunological effects of MY-1, a new biological response modifier, on postoperative gastric cancer patients. A total of 90 patients were randomly allocated either to an MY-1 treated or an untreated group. MY-1 was given 3 times a week from the 4th postoperative day for a period of 3 weeks. Immunological parameters of the patients, such as lymphocyte subsets measured with flow cytometry using various monoclonal antibodies, blast transformation responses against PHA, ConA, and PPD, natural killer activity of peripheral lymphocytes, and skin test for MY-1 and PPD, were evaluated preoperatively, before and after MY-1 treatment. The results of the two color staining method with flow cytometry showed that the population of lymphocytes positive for both OKT8 and Leu15 antigens (suppressor cells) was statistically less, and that the population of lymphocytes positive for OKT8 and negative for Leu15 antigens (killer cells) was statistically increased in patients treated with MY-1 compared with the control group.

Adult↗
PubMed1985

Prevention of the agonist binding to gamma-aminobutyric acid B receptors by guanine nucleotides and islet-activating protein, pertussis toxin, in bovine cerebral cortex. Possible coupling of the toxin-sensitive GTP-binding proteins to receptors.

Using the membranes treated with Triton X-100, we studied the interaction between gamma-aminobutyric acid (GABA)B receptors and the GTP-binding proteins which are the substrates for ADP-ribosylation by the islet-activating protein (IAP), pertussis toxin. The addition of guanine nucleotides to the membranes markedly decreased the binding of GABA to GABAB receptors. Preincubation of the membranes with IAP plus NAD caused ADP-ribosylation of the 41,000- and 39,000-Da proteins selectively and decreased GABA binding to GABAB receptors in a time- and dose-dependent manner. This decrease of binding appeared to be due to the reduction of receptor affinity for agonist. The GTP-binding proteins which are ADP-ribosylated by IAP were purified from the membrane fraction of bovine cerebral cortex. The addition of the purified GTP-binding proteins to IAP-treated membranes restored the high affinity binding of GABA to GABAB receptor. The two GTP-binding proteins which were resolved by octyl-Sepharose column chromatography showed similar efficacy in restoring GABA binding. Thus, GABAB receptors are coupled to GTP-binding proteins, IAP-specific substrates, in the brain membranes.

Adenosine Diphosphate Ribose↗
PubMed1985

Purification and characterization of recombinant human interleukin-2 produced in Escherichia coli.

Recombinant human interleukin-2 (rIL-2) produced in Escherichia coli was purified to apparent homogeneity by cation exchange chromatography and reverse phase high performance liquid chromatography. The amino acid composition, amino terminal amino acid sequence, and carboxyl terminal amino acid were consistent with those deduced from the cDNA sequence. Besides the molecular species with the amino terminal Ala, the purified preparation contained another species having an additional Met residue at the amino terminus corresponding to the initiation codon AUG. The molar absorption coefficient of rIL-2 was determined to be 9.58 X 10(3) M-1 cm-1 at 280nm in water. Ultracentrifugal analyses revealed that it existed as a monomeric form in 0.1 M NaCl. The apparent sedimentation coefficient (S20,w) was calculated to be 1.8 S.

Amino Acids↗