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Biomedical subjects

H Amano

Publications and source records attributed to H Amano.

At least 217 records · Page 12Linked to original sources
PubMed1987

A trial for kinetic evaluation of the antagonistic potency of several beta-antagonists on presynaptic beta-adrenoceptors.

The antagonistic potency, pA2, of several non-selective beta-antagonists on presynaptic beta-adrenoceptors was evaluated using a parallel line assay and MacKay's equation against isoproterenol-induced increases in 3H release in isolated guinea-pig pulmonary arteries preloaded with 3H-norepinephrine. Cumulatively applied isoproterenol at 10(-9) M, 10(-8) M and 10(-7) M dose-dependently increased 3H release evoked by transmural field stimulation at 1 Hz. beta-Antagonists tested dose-dependently antagonized the isoproterenol-induced increases. The order of pA2 was carteolol (11.23 +/- 0.09) greater than nadolol (9.78 +/- 0.05) greater than pindolol (9.59 +/- 0.03) greater than propranolol (9.26 +/- 0.17). Carteolol has the highest pA2 and is a useful tool for clarifying whether or not presynaptic beta-adrenoceptors tonically function.

Adrenergic beta-Antagonists↗
PubMed1987

[The pharmacokinetics of cisplatin and its influence on renal functions based on different infusion methods].

The pharmacokinetics of cisplatin, together with its renal toxicity in relation to different infusion methods were examined. The subjects were 21 in-patients suffering from pulmonary carcinoma treated by anti-neoplastic agents including cisplatin. The patients included 12 given a 5-division dosage, 5 cases given 24-hour continuous infusion, 6 given 12-hour continuous infusion, and 7 given 6-hour continuous infusion. Cisplatin was determined as the concentrations of Pt in plasma and non-protein-bound Pt. Also, as indices of renal function, NAG in urine together with beta 2-microglobulin were examined. No substantial difference could be found in Pt concentration in plasma upon completion of the respective infusion methods. A dual-phase attenuation curve was obtained after the completion of infusion and the half-life period of the beta-phase was around 200 hours. With respect to non-protein-bound Pt concentrations, the 5-division dosage showed the highest value, which was considered to be a temporary phenomenon, while with continuous infusion, the shorter the infusion period, the higher the value became. With respect to the amount of NAG excreted in urine, 12-and 6-hour continuous infusion showed the higher value in comparison with the others in terms of the maximum value and the total amount. With regard to beta 2-microglobulin, 6-hour continuous infusion showed the highest value. The above results therefore suggest that in continuous infusion, the shorter the infusion period the greater the degree of renal tubule injury, and that particularly, 6-hour continuous infusion will possibly cause dysfunction of the renal tubules.

Acetylglucosaminidase↗
PubMed1987

[Presence of dehydrogenases of the pentose phosphate pathway in boar spermatozoa and testis].

There is insufficient evidence of direct oxidation of glucose through the pentose phosphate cycle in mammalian spermatozoa. We separated the key enzymes (G6P-DH, 6PG-DH) in the pentose pathway using 2',5'ADP-Sepharose 4B. The purpose of this study is to establish the intracellular location of these two enzymes in boar spermatozoa and testis by histochemical techniques. Histochemical localization of the two pentose phosphate pathway dehydrogenases was achieved by the use of the tetrazolium salt nitro blue tetrazolium (Nitro BT). Both G6P-DH and 6PG-DH was present in the mid pieces of boar spermatozoa and in the Leydig cells and seminiferous tubules of testis. The present findings indicate that the pentose pathway could be involved in the energy production of spermatozoa and that these enzymes may be important in supplying NADPH for steroid synthesis in the testis.

Animals↗
PubMed1986

Vasopressin-induced pressor responses in rats to bilateral electrolytic lesioning of the caudal portion of the nucleus tractus solitarii.

Bilateral electrolytic lesioning of the nucleus tractus solitarii elicited a pressor response in rats with spinal transection. This response was abolished by a vasopressin pressor antagonist and plasma vasopressin was increased during the response. This evidence suggests that the nucleus tractus solitarii is involved in inhibiting vasopressin release and that an impaired function would lead to an enhancement of vasopressin release, to the extent of eliciting a pressor response.

Animals↗
PubMed1986

Adrenergic innervation of the Eustachian tube. Histochemical and electron-microscopic study.

The presence of adrenergic nerves in the Eustachian tubes of guinea pigs was observed using the Falck-Hillarp fluorescence method. Abundant adrenergic nerve are forming networks around blood vessels in all tubal regions. Adrenergic fibers also surround the tubal glands. The precise locations of adrenergic nerve terminals in the tube were demonstrated by electron microscopy following application of a false transmitter. Adrenergic nerve terminals were found in abundance just beneath the smooth muscle layer of the arteries in each part of the tube and close to the myoepithelial cells of the tubal gland.

Adrenergic Fibers↗
PubMed1986

Further evidence for tonically functioning presynaptic beta-adrenoceptors in guinea-pig pulmonary arteries.

Effects of dl- and d-carteolol alone on the release of tritium evoked by transmural field stimulation at 1 Hz were investigated in spirally cut guinea-pig pulmonary arteries preloaded with [3H]-norepinephrine. Cumulatively applied dl-carteolol 10(-8) M, 10(-7) M and 10(-6) M readily inhibited the release of tritium in a concentration-dependent manner, whereas the same concentrations of d-carteolol produced no effect. In conclusion, presynaptic beta-adrenoceptors in guinea-pig pulmonary arteries tonically function to facilitate the release of the transmitter norepinephrine.

Animals↗
PubMed1986

L-thyroxine, cortisol, and diet affect the postnatal development of the facial part of the skull in developing rats.

In rats, the effects of L-thyroxine (T4; 0.2 micrograms/g body weight), hydrocortisone (HC; 5 micrograms/g body weight) and mastication on the postnatal development of the facial part of the skull were examined. Administration of T4 and/or HC to rats for 5 consecutive days from day 5 after birth induced a precocious increase in the ratio of the facial length to the head length. The effects of these hormones decreased with the progression of weaning, and after the 20th postnatal day, the hormones had no effects on the postnatal development of either (facial and head) part of the skull. Moreover, these hormones played an additive role in the growth of facial part. On the other hand, continuous suckling from birth to the 30th postnatal day caused a significant decrease in the ratio of the facial length to the head length. These results suggest that increases in the circulating levels of T4 and HC in suckling rats and mastication in the weaning period are involved in development of the postnatal development of the facial part of the skull.

Aging↗
PubMed1986

[Application of NMR-CT in the staging of cancer of the digestive organs].

To assess the potential of NMR-CT for demonstrating cancer of the digestive organs, we examined a total of 232 patients (89 with esophageal cancer, 52 with liver cancer, 40 with colorectal cancer, 9 with pancreatic cancer, 9 with gastric cancer, and 33 with other diseases). NMR-CT has many features, but we use especially those features which it is possible to select not only in the transverse plane but also in the coronal and sagittal planes, and it has excellent soft tissue contrast resolution. Our machine is a Picker International NMR-CT using a superconducting magnet of 0.256 tesla. Diagnosis of lymph node involvement of esophageal cancer. Using only the coronal plane, each patient was scanned by the spin echo technique (TE = 40, TR = 400) from the plane of the descending aorta to the plane of the trachea 1 cm in thickness, at 1 cm intervals, continuously. All the vessels were clearly differentiated as no-signal regions, especially in coronal images, from areas of carcinomatous involvement. Lymph nodes were identified as intense grey masses in fat tissue of high intensity. Twenty cases were proved by surgery or autopsy, and it was possible to assess 160 lymph-node groups. A total of 25 patients were imaged as having positive lymph nodes, but 17 of them had metastasis-positive nodes. In other 135 nodes imaged as negative lymph nodes, only two had metastasis and 133 were negative for metastasis. Overall accuracy was 93.8%. Diagnosis of liver cancer. Intrahepatic vessels were clearly imaged without using contrast enhancement in NMR-CT, so it was easy to diagnose the segment containing the tumor and to detect tumor emboli in the portal vein. The capsule was imaged in 84% (16/19) using IR techniques, although only 37% (7/19) could be imaged by X-CT. Diagnosis of colorectal cancer. Using the sagittal plane, the sacrum, urinary bladder and other organs were imaged better parallel to their axis, so that the relationship between rectal cancer and surrounding organs could be clearly visualised with NMR-CT. With regard to lymphatic metastasis, coronal imaging was useful for picturing mesenteric and pelvic vessels, so that lymph nodes were imaged as low-intensity masses along the vessels. Lymph metastasis almost 1 cm size can be detected using coronal NMR-CT.

Digestive System Neoplasms↗