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Biomedical subjects

T Shimada

Publications and source records attributed to T Shimada.

At least 991 records · Page 55Linked to original sources
PubMed1980

Genotoxicity of the antihypertensive drugs hydralazine and dihydralazine.

The genotoxicity of the antihypertensive agents hydralazine and dihydralazine was tested in mammalian cells and bacteria. Both drugs elicited DNA repair in rat hepatocyte primary cultures. In the Ames test, both with and without an S-9 fraction, hydralazine was mutagenic in strains TA100 and TA1537, whereas dihydralazine was weakly mutagenic in strain TA1537. These findings support the observation that hydralazine is carcinogenic in mice. The carcinogenicity of many chemicals results from interaction with DNA. Since these studies demonstrate that hydralazine and dihydralazine damage DNA in mammalian cells, these drugs should be viewed as potential human carcinogens.

Acetylation↗
PubMed1980

A survey of Plesiomonas shigelloides from aquatic environments, domestic animals, pets and humans.

We conducted a survey during the period from 1974 to 1976, to determine the distribution of Plesiomonas shigelloides in human faeces, the intestinal contents of cattle, swine, poultry, dogs, cats, fresh water fish, and river water and sludge from wet riverbeds in the vicinity of Tokyo. Isolation of the organisms was performed by using Salmonella-Shigella (SS) agar and deoxycholate-hydrogensulphide-lactose (DHL) agar plates. P. shigelloides was isolated from 3 (0.0078%) of 38454 healthy Tokyoites, 37 (3.8%) of 967 dogs, 40 (10.3%) of 389 cats, 25 (10.2%) of 246 fresh water fish, 64 (12;8%) of 497 river water samples, and 2 of 19 (10.5%) sludge samples. Of 302 strains isolated, from dogs, cats, fresh water fish, river water and healthy carriers, 196 were typed to 50 serovars. Most of the serovars were found to be similar to strains isolated from patients with gastroenteritis due to P. shigelloides.

Animals↗
PubMed1980

Modification of regional function of ischaemic myocardium by the alteration of arterial pressure in dogs.

The effects of alterations of arterial pressure by nitroprusside and methoxamine on regional myocardial function were studied during total coronary occlusion and during partial coronary constriction in open chest dogs. Animals were instrumented with a left ventricular micromanometer, an electromagnetic flow probe around the left circumflex coronary artery, and three pairs of ultrasonic crystals in a control, marginally ischaemic, and ischaemic segments. In nine dogs, when the coronary artery was totally occluded by a hydraulic cuff placed distal to the flow probe, the end-diastolic length of all three segments was increased, and shortening was rapidly replaced by systolic expansion in the ischaemic segment. Active shortening decreased by 68% in the marginal segment, while it increased by 21% in the control segment. With nitroprusside infusion, peak systolic pressure was reduced from 15.2 to 11.3 kPa and hypokinesis of the marginal segment was improved to 45% of control value with a concomitant decrease in end-diastolic length by 5%. With methoxamine, left ventricular systolic pressure was elevated to 18.5 kPa, and marginal segment shortening further deteriorated to 19% of control with chamber enlargement. In 6 dogs, coronary flow was limited by a screw-driven metal clamp. When mean coronary flow was reduced by 50% of control value, stable hypokinesis was produced in the ischaemic segment. Nitroprusside infusion induced the same haemodynamic changes, however, shortening of the ischaemic segment deteriorated further and a passive bulge appeared. Methoxamine improved the percentage shortening from 1.2 to 6.4%. Thus, interventions with an agent which changes afterload in left ventricular ejection have multiple and complex effects on the contractile function of the ischaemic myocardium and, depending on the magnitude of coronary blood flow reduction, a potentially beneficial drug can be determined to an ischaemic myocardium.

Animals↗
PubMed1980

Ultrastructural studies on the pancreatic polypeptide cell of the rat with special reference to pancreatic regional differences and changes induced by alloxan diabetes.

Rat pancreatic tissues were fixed with our modification of Dalton's fixative and the islets from various pancreatic regions were examined by electron microscopy. In addition, the effect of the alloxan-diabetic state on the pancreatic polypeptide cell was examined at the ultrastructural level. The results are as follows. (1) The islets of the rat contain four types of glandular cells: A, B, D and PP cells. (2) The PP cell is characterized by approximately 170-millimicron-sized secretory granules with a rather ill-defined core. The ultrastructure of this type cell is described in some detail. (3) In the pancreatic portion which hooks around posterior to the superior mesenteric vessels, PP cells are abundant and some of them are markedly degranulated. Their cell organelles, such as the nucleolus, granular endoplasmic reticulum and Golgi apparatus are well developed. (4) In alloxan-diabetic rats, B and PP cells show disappearance and numerical increase, respectively. In the PP cells, hypertrophy of the Golgi apparatus and appearance of extremely electron-translucent secretory granules are noted.

Animals↗
PubMed1980

Lipid peroxidation and antioxidants in the rat lung during development.

The extent of lipid peroxidation and the levels of its antioxidants such as superoxide dismutase (SOD), catalase and glutathione peroxidase (GSH-Px) were determined on lung tissues of the fetal, newborn and adult rat. Lipid peroxide formation was slight in the fetal period but augmented after birth reaching a peak at about 10 days after birth. The peroxide concentration then gradually declined with development and the adult level was found comparable to the fetal level. In the examination of the developmental defensive mechanism on the basis of assays for the aforementioned antioxidant enzymes in lung tissue, the SOD activity was low in fetuses reaching approximately 90% of the adult level at 10 days of life. Catalase was extremely low in concentration at all times, and age-related variations could not be definitely obtained. GSH-Px was also measured low in the fetal period and during 20 days after birth, but a subsequent gradual rise resulted in threefold greater activity in adults than in fetuses.

Aging↗
PubMed1979

Lipid peroxidation in maternal and cord blood and protective mechanism against activated-oxygen toxicity in the blood.

Concentrations of a peroxidation product (malondialdehyde), fluorescent chromophores, lipofuscin-like fluorescent products, superoxide dismutase, catalase, glutathione peroxidase, and vitamin E in the maternal blood and the cord blood were determined and the results obtained were related to the estimation of lipid peroxidation and protective mechanism against uncontrolled oxidative processes in late pregnancy. Serum levels of fluorescent products were higher in the maternal blood than in the cord blood, indicating less frequent lipid peroxidation in the fetus than in the mother. In support of this assumption, the three protective enzymes and vitamin E were present in relatively lower concentrations in the cord blood. Sudden exposure of the newborn infant to a normobaric atmosphere after beginning breathing seems, therefore, to cause oxidation of red blood cell membrane, denaturation of the membrane, inducing hemoglobin breakdown, and consequently hemolysis.

Catalase↗