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Biomedical subjects

M Tagami

Publications and source records attributed to M Tagami.

At least 73 records · Page 4Linked to original sources
PubMed1986

Morphological and functional differentiation of cultured vascular smooth-muscle cells.

In numerous investigations using cultured smooth-muscle cells, investigators have consistently added 10-20% fetal calf serum (FCS) to the medium to maintain viable cells. In the present study we utilized an optical technique to investigate whether smooth-muscle cells, cultured with or without FCS, maintain their contractile activity in vitro. With such optical measurement, we were able to detect signals due to spontaneous contractions, in muscle cells cultured in FCS-free medium for up to 8 days, and, for the first time, were also able to observe the conduction of these cell contractions. The ultrastructural characteristics of cultured smooth-muscle cells during contractile activity, were also examined by electron microscopy. The cells were mature and well-differentiated, and were packed with numerous myofilaments. They had developed long cell processes, and were linked to one another by gap junctions. These observations indicated that the smooth-muscle cells, cultured without FCS for 7 to 8 days, were morphologically mature and maintained their contractile activity, whereas the cells cultured in FCS-containing medium showed no detectable signs of contractile activity.

Animals↗
PubMed1985

Electronmicroscopic autoradiographic study of the distribution of 3H-diltiazem in myocardial cells.

The distribution of 3H-diltiazem in myocardial cell organelles was studied using an electronmicroscopic autoradiographic technique. At 3, 5 and 10 min after 3H-diltiazem injection, silver grains, which indicate the existence of diltiazem, were detected in plasma membranes and intracellular organelles. Silver grains in T systems were observed more frequently at 3 min than at 5 and 10 min. In contrast, silver grains in sarcoplasmic reticula and mitochondria apparently increased with the passage of time. These findings suggest that diltiazem is transported through the T system and may accumulate within the sarcoplasmic reticula and mitochondria. Furthermore, our study revealed morphologically for the first time that the intracellular sites of action where diltiazem was directed were possibly the mitochondria.

Animals↗
PubMed1984

Common cellular disposition to hypertension and atherosclerosis.

The genetically hypertensive rat models, spontaneously hypertensive rats (SHR) and especially stroke-prone SHR (SHRSP), both develop arterial fat deposits quickly when fed high cholesterol diets. Therefore the morphological and functional characteristics of cultured vascular smooth muscle cells (SMC) from the aorta of SHR, SHRSP and normotensive Wistar-Kyoto (WKY) rats have been compared in order to demonstrate the common cellular mechanisms which induce hypertension and atherosclerosis. Cultured SMC became differentiated after short-term foetal calf serum exclusion from the medium, and despite the general concept of their noncontractility there was opticometric evidence that subcultured SMC contract spontaneously. Smooth muscle cells from SHR, but especially from SHRSP, showed enhanced proliferation which was inhibited by a Ca-antagonist, and accelerated lipid incorporation. It is concluded that these SMC are primarily predisposed to hypertension as well as to atherosclerosis.

Animals↗
PubMed1983

PaO2 and intratracheal pressure in oscillatory ventilation in experimental respiratory failure.

In order to study the effect of high frequency ventilation on the pulmonary gas exchange in respiratory failure, we measured the PaO2 and other pulmonary gas exchange parameters for ventilatory rates of 0.5, 1.2, 4.8, and 16 Hz in dogs, to which acute respiratory failure was created by intravenous infusion of oleic acid. Either the mean intratracheal pressure or the end-tidal intratracheal pressure was controlled. A loud-speaker ventilator of our own design was modified so as to enable variation of the intratracheal pressure. Ventilation was measured using an ultrasonic instrument which counts the number of turbulent eddies. The tidal volume was set slightly higher than that was determined for healthy animals, but the resulting PaCO2 values were consistently higher than normal when PaO2 values were low. With the mean intratracheal pressure kept constant at 5, 10, and 15 cm H2O, PaO2 values with the FIO2 of 1 were between 41 and 46 at mPit of 5, 65 and 82 at 10 cm H2O, 278 and 423 at 15 cm H2O. No increase in PaO2 was observed with the increase in respiratory frequencies. If anything, a slight reduction in PaO2 at 8 and 16 Hz was observed, though not statistically significant. With the end-tidal intratracheal pressure constant, PaO2 varied but again correlated well with the mPit.

Animals↗
PubMed1982

Relationship between monensin and sulphur amino acid requirements in broiler chickens.

1. Diets containing 80, 100, 125, 150, 175 or 200 mg monensin/kg were fed to broiler chickens from 0 to 28 d in cages that prevented access to excreta. 2. Growth was depressed with 125 mg monensin or more/kg and food intake tended to decrease. Feathering was adversely affected with 175 mg or more/kg. 3. In a similar experiment, diets containing 8.8, 9.1, 9.4, 9.7 and 10.1 g total sulphur amino acids (SAA)/kg were supplemented with 125 or 80 mg monensin/kg and compared with a diet containing 8.8 g SAA and 33 mg robenidie/kg. 4. With 125 mg monensin/kg, body-weight gain was significantly less than that of birds receiving robenidine if dietary SAA content was 9.4 g or less/kg. With 9.7 g SAA or more/kg, gain in birds receiving monensin was similar to that of birds receiving robenidine. 5. Monensin at 125 mg/kg therefore appears to increase SAA requirement.

Amino Acids, Sulfur↗
PubMed1982

Ventilatory volume and pressure required for oscillatory ventilation in dogs.

We determined the ventilatory volume and pressure required to maintain a PaCO2 of 40 mmHg in dogs at between 0.5 and 16 Hz. The ventilator used was that incorporating a powerful, specially made loudspeaker to which a sine-wave signal was introduced. A windmill-type flowmeter measured the minute volume. The tidal volume, expressed per kg of body weight, was 16.1 at 0.5 Hz, decreasing linearly with log f, and reaching a value of 6.1 ml/kg at 16 Hz. The minute volume increased 10 times from 0.5 to 16 Hz. The intratracheal pressure was 12 to 13 cmH2O between 0.5 and 2 Hz, rising to 16 at 4 Hz and finally reaching 77.2 cmH2O at 16 Hz. The PaO2 values were always above 500 mmHg when FIO2 was 1.0. The frequency-impedence data were analyzed for R, I and C values. The fitting of the data to an R-I-C series model was good, but the R values obtained were considerably higher than those reported using a smaller amplitude of oscillation.

Animals↗
PubMed1981

High-frequency animal ventilator using a loudspeaker and its gas exchange characteristics.

A high-frequency ventilator was designed using a loudspeaker as a piston, driven by a power-amplifier. A sine-wave signal was introduced into the amplifier from an electronic oscillator. The mechanical and gas exchange characteristics of the ventilator were studied in vitro and in dogs. The volume output per stroke, when open to air, was between 100 and 200 ml up to 7 Hz, then gradually decreased as the frequency increased. A Wright respirometer appeared to measure the volume flow fairly accurately up to 14 Hz. The pressure output against a closed volume of 1.1 liters achieved a maximum of 29 mmHg at 7 Hz. It gradually decreased as the frequency was changed from 7 Hz. The loudspeaker worked in such a way that the volume output decreased considerably when it was forced to move against a closed space to generate pressure. Adequate ventilation was achieved in all dogs from 1.4 to 10 Hz. At 14 Hz, the results were variable, and at 20 Hz and above, gross hypoventilation always resulted. The PaO2 values were always over 440 mmHg when 0.8 liter/(kg . min) of oxygen was supplied into the respiratory circuit. A speaker ventilator has the advantage of easy assembly and the possibility of applying various flows by electrical control. Its disadvantages are a lack of power and the difficulty in establishing ventilatory volumes without actual measurement.

Animals↗