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Biomedical subjects

Y Shindo

Publications and source records attributed to Y Shindo.

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

Hypoxic reduction in blood flow velocity in pulmonary arterioles and capillaries.

A small ring chamber (I.D. = 6 mm) was placed on the exposed lung of anaesthetized bullfrogs. A localized hypoxia was induced in the ring chamber by introducing nitrogen in it. Blood flow velocity in pulmonary microvessels was measured by means of a laser Doppler microscope. The mean blood flow velocity was 1.98 +/- 0.45 and 1.52 +/- 0.10 mm/sec during the control condition in arterioles and capillaries, respectively. It was then reduced by the localized hypoxia to 1.63 +/- 0.32 and 1.33 +/- 0.08 mm/sec in arterioles and capillaries, respectively. The reduction, when expressed in the percentage ratio to the control flow velocity in each blood vessel group, was significantly larger in arterioles than in capillaries. A phase delay in the pulsation of the flow velocity contour was detected only in arterioles. These differences between pulmonary arterioles and capillaries in response to the localized hypoxia may be attributed to the dense interconnection of capillary network extending beyond the localized hypoxic area to the normoxic area.

Animals↗
PubMed1984

A nanosecond fluorometer for studies of rheological aspects of biomembranes.

A nanosecond fluorometer was designed to study the microdynamics of biomembranes. The overall system consists of a nitrogen laser for excitation of fluorophores, optics consisting of polarizers, monochromators, a single photon counting system having a multichannel time to amplitude converter controlled with a microcomputer and a data processing system. The laser pulse for excitation was polarized with a polarizer. Anisotropically polarized DPH fluorescence could be measured with a time resolution smaller than 5 nsec. The parallel decay curve of DPH fluorescence was higher than the perpendicular decay curve in erythrocyte membrane over the whole decay time. No anisotropism was recorded in a tetrahydrofuran solution. These results suggested that the motion of DPH molecules in erythrocyte membranes was restrained and that the present system provided information on rheological aspects of molecular dynamic structure of biomembranes.

Diphenylhexatriene↗
PubMed1984

Toxicological studies on a new macrolide antibiotic, midecamycin acetate (miocamycin). Part VI-1. Acute toxicity in infant mice in comparison with young adult mice.

Sutherland and Weiss et al. reported cases of newborn human deaths or Gray syndrome after overdosage of chloramphenicol. In general, it has been reported that the acute toxicities of drugs are enhanced in immature animals compared with adult animals. The objective of this study was to determine the LD50 values in infant (5-day-old) and young adult (5-week-old) male and female mice after single subcutaneous and oral administration of MOM, non-crystalline solid and to estimate the toxicity ratio of those LD50 values. LD50 values of MOM, non-crystalline solid, were more than 5,000 mg/kg and the lethal toxicity was the same in infant and adult mice. Toxicity ratios were not obtained.

Age Factors↗
PubMed1984

Toxicological studies on a new macrolide antibiotic, midecamycin acetate (miocamycin). Part VI-2. Acute toxicity in infant rats in comparison with young adult rats.

In the present acute toxicity studies on MOM, non-crystalline solid, with infant male and female rats (5-day-old) and young adult male and female rats (5-week-old), it is confirmed as follows: LD50 values were estimated more than 5,000 mg/kg in both cases of subcutaneous and oral administrations. MOM, non-crystalline solid, did not exhibit any toxic effects similarly as previously reported with infant male and female mice and young adult male and female mice. There might be no definite age difference in toxicity between young and adult rats as LD50 values were estimated more than 5,000 mg/kg in independence upon the age. There might be no definite species difference in toxicity between mice and rats.

Age Factors↗
PubMed1984

[The mutagenicity evaluation of MT-141, a new cephamycin].

Mutagenicity of MT-141, a new cephamycin, was evaluated by in vitro and in vivo assays. MT-141 did not induce mutations of the test strains, Escherichia coli WP2 (uvr A) and Salmonella typhimurium TA1535, TA1537, TA1538, TA100 and TA98, with and without metabolic activation in vitro. In bone marrow micronucleus assay with male mice, MT-141 showed no induction of micronucleated polychromatic erythrocyte at 6 hours and 30 hours after administration. In addition MT-141 was found not to cause any dominant lethal effects on male mice for 8 weeks after administration.

Animals↗
PubMed1983

The micronucleus test with mouse spleen cells.

The results of this study show that the micronucleus test can be carried out with mouse spleen cells as well as with cells from bone marrow. Polychromatic erythrocytes occurred in the spleen at a frequency of about 9% of the whole spleen cells compared with about 13% in the bone marrow. 3 test compounds were used to compare the frequency of micronuclei in cells from the 2 tissues. Mitomycin C and cyclophosphamide induced micronucleated polychromatic erythrocytes in both spleen and bone marrow. Fosfomycin, an antibiotic having a broad spectrum of antimicrobial activities, did not induce micronucleated erythrocytes in either organ.

Animals↗
PubMed1983

Measurements of erythrocyte flow velocity by means of grating laser microscope.

The possibility of measuring erythrocyte flow velocity by means of grating laser microscope has been examined in an in vitro test using erythrocytes smeared on glass plates and in vivo using microvessels in the web of a frog foot. Magnified projections of flowing erythrocytes are spatially filtered by a simple glass plate grating and then detected by a photomultiplier. Output signals from the photomultiplier are first electronically filtered so as to yield oscillating burst-like wave signals. Moving erythrocytes resulted in burst-like oscillation in output signals whose wave period (T) changed with their velocities. These results suggest that the velocity (V) of erythrocytes could be given by V = d/MT, where d and M represent the grating constant and the optical magnification, respectively. The requirement for the establishment of this relation was examined by the microscopic observation of smeared erythrocyte preparation. It was shown that the flow velocity of erythrocyte could be measured even when the size of magnified images of erythrocytes strongly exceeded the value of d and even when many erythrocytes existed. A preliminary experiment to confirm the possibility of methodological adaptation was made by measuring the flow velocity in venules of foot web of frogs. Heart rate increased in all six frogs studied when the frog body was warmed. However, the peripheral flow velocity increased only in three frogs, while it remained almost unaffected in the other three. This result suggests that the frog peripheral microcirculation is affected by complicated intrinsic factors.

Animals↗
PubMed1983

Effect of expectorants on relaxation behavior of sputum viscoelasticity in vivo.

We studied the effects of expectorants (mucolytic agents) in vivo on the relaxation behavior of sputum viscoelasticity. Seven female and thirty-three male patients (56.8 +/- 19.3 yrs, range: 21 to 82 years old) with a chronic pulmonary disease except bronchial asthma were studied. They were randomly put into the control group or a group which would be given oral treatments with an expectorant for a week after a one week washout period. The groups were as follows: Group I (n = 8), control; Group II (n = 7), Bromhexine hydrochloride 24 mg per day; Group III (n = 10), Ambroxol 90 mg per day; Group IV (n = 9) alpha - Chymotrypsin buccle 100 ch.u. per day; Group V (n = 6), Serratiopeptidase 30 mg per day. In Groups IV & V, frequency dependence of sputum viscoelasticity at the range of omega = 10(-3) to 10(0) rad.sec-1 were clearly changed after the treatments, and the magnitude of the relaxation and its main relaxation time were significantly increased. On the other hand, in Groups I, II & III, no significant changes of the frequency dependences were observed. These findings suggest that proteolytic enzymes administered orally work on the molecular structure of sputum, and break down their linkages between subunits of the structure.

Adult↗