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Biomedical subjects

M Horimoto

Publications and source records attributed to M Horimoto.

123 records · Page 7Linked to original sources
PubMed1981

Effect of transpulmonary pressure on blood-flow velocity in pulmonary microvessels.

Flow velocity in the microvessels (30 to 90 micron in diameter) on the exposed lung surface of anesthetized bullfrogs was measured during positive lung inflation by means of a laser Doppler microscope. From the pulsatile flow-velocity contour generated by cardiac cycles, mean flow velocity (MV) and pulsatile amplitude (PA) were calculated and their alterations were studied as a function of transpulmonary pressure (TPP). At the lowest TPP of 1.3 +/- 0.8 cm H2O (mean +/- SD), MV and PA were 1.72 +/- 0.33 and 0.45 +/- 0.27 mm/sec, respectively. With moderate increments in TPP up to 2.8 +/- 1.3 cm H2O, both MV and PA increased, attaining maximum values of 2.11 +/- 0.42 and 0.69 +/- 0.28 mm/sec, respectively. But with further inflation they began to decrease, and there was a marked reduction or a complete arrest of blood flow at excessively high TPPs (6 to 9 cm H2O). With reduction of previously increased TPP, the alterations in MV and PA followed a pattern similar to that noted during elevation of TPP. There was an apparent hysteresis in both the MV-TPP and PA-TPP curves, most marked when excessively high TPP was applied.

Animals↗
PubMed1981

Prevalence of feline viral antibodies in random-source laboratory cats.

Over a period of 1973 to 1979, a serologic survey of virus infections was conducted on feline sera collected in four universities which located in different prefectures; Obihiro, Saitama, Kanagawa and Tokyo. A significant hemagglutination-inhibition (HI) antibody titer of 1 : 8 or higher to feline panleukopenia virus (FPLV) was detected in 130 (58%) of the 226 sera used. No remarkable difference in the HI antibody prevalence in cats to FPLV was recognized by years or localities. Of a total of 188 cats tested, 99 (53%) presented positive serum neutralizing (SN) antibody titers to the No. 1 strain of feline calicivirus (FCV). Especially in Kanagawa, 17 (77%) of the 22 cats had positive SN titers. However, only 42 (22%) of the 188 sera showed positive SN titers to the Kyoritsu strain of FCV. Such lower positivity in the cats was observed with 13% in the SN test to human reovirus type 3 (Reo-3). The incidence of positive SN antibodies to feline rhinotracheitis virus (FRV) also remained in low values of 20 to 27% with the exception of high percentage of 86 in Tokyo. The dissemination of FPLV, FRV, FCV and Reo-3 was briefly discussed in relation with the age distribution of viral antibodies in cats.

Animals↗
PubMed1981

Transvascular osmotic flow reflected by changes in plasma oncotic pressure of anesthetized dog.

To assess overall bodily transvascular fluid flow due to osmotic imbalance between blood and interstitial fluid during or after addition of hypertonic saline, sugar-, albumin- and dextran solutions or CO2 mixture to blood, arterial blood colloid osmotic pressure (COP) of anesthetized dogs was continuously measured with a needle-type colloid osmometer. Plasma volume change (delta Vp) was estimated from the changes in either the equivalent albumin concentration (C) or the albumin concentration equivalent to plasma COP, which was well confirmed in inanimate model experiments. Carbon dioxide inhalation caused RBC swelling (1.5% volume increase/10 mmHg of PCO2). Intravenous injection of hypertonic solutions resulted in transient osmotic flow (8.5 +/- 2.2 ml/g of solute per kg of animal weight by NaCl, and 1.7 +/- 0.4 by glucose), and albumin and dextran also induced fluid flow (1.3 +/- 0.4 by albumin and 2.2 +/- 0.7 by dextran), which depended on van't Hoff's law and reflection coefficient of solutes.

Animals↗
PubMed1981

[Measurements of blood flow velocity in pulmonary microvessels with laser-Doppler microscope and investigation of several factors affecting the blood flow velocity (author's transl)].

To examine the blood flow in pulmonary microvessels and its change during positive lung inflation and deflation as well as during regional lung hypoxia or hypercapnia, the blood flow velocity in the microvessels which were observed on the exposed lung surface of anesthetized bullfrogs was measured. This was performed by means of a laser-Doppler microscope and both mean flow velocity (MV) and pulsatile amplitude (PA) were calculated from the obtained flow velocity contour. Hypoxia (pure N2) or hypercapnia (10% CO2) was applied on the regional lung surface of 6 mm in diameter. The blood flow in the pulmonary microvessels was pulsatile and its pulsatility was greatest in arterioles and smallest in capillaries. MV and the ratio of PA to MV in capillaries were 1.46 mm/sec and 0.20, respectively. This ratio was considerably smaller than that in human pulmonary capillaries, which was previously measured by using body plethysmography. The reason for this discrepancy was discussed. During lung inflation and subsequent deflation, the alterations in MV and PA against transpulmonary pressure (TPP) revealed an optimum TPP and an apparent hysteresis. During lung inflation MV was slightly increased until TPP reached about 2.8 cmH2O but was markedly decreased at the larger TPP than the value. During subsequent deflation, MV was slightly lower at any given TPP than during inflation but its change was almost parallel to that in inflation. The change in PA was similar to that in MV. The observed alteration in flow velocity in pulmonary microvessels seemed related to the geometric change in pulmonary vessels. Both lung regional hypoxia and hypercapnia induced the decrements in MV and PA in pulmonary microvessels, which were caused by the vasoconstriction in arterioles and venules. The maximal percentage change in MV and PA in capillaries were -11% and -35% during hypoxia, and -13% and -44% during hypercapnia.

Animals↗
PubMed1979

Reduced deformability of erythrocytes exposed to hypercapnia.

The effect of hypercapnia on the deformability of erythrocytes was studied by means of a nuclepore membrane filter method. A decrement of the deformability by 20--40% was observed when PCO2 was increased from 50 mm Hg to 200 mm Hg, accompanied with an increment of 5% in hematocrit value.

Carbon Dioxide↗
PubMed1979

Blood flow velocity in pulmonary microvessels of bullfrog.

Flow velocity in the pulmonary microvessels of the exposed lung of bullfrogs was measured by means of a laser Doppler microscope of an oblique backward mode, together with a signal-analyzing system having a time sharing circuit triggered by the R-wave of the ECG. By these means, measurements of the changes of flow velocity contour in the cardiac cycle were made. Flow velocity was clearly pulsatile in response to cardiac cycles in all microvessels including capillaries. Flow velocities in the arteriole and venule consistently decreased for a short period after the R-wave (84 +/- 33 msec (mean +/- SD) in the arteriole and 130 +/- 31 msec in the venule, respectively) and rapidly increased up to a maximicronm value. The mean flow velocities in arterioles (diameter 50 +/- 17 micron) and venules (39 +/- 9 micronm) were 2.29 +/- 0.32 and 2.30 +/- 0.27 mm/sec. The amplitudes of pulsatile flow in these vessels were 0.83 +/- 0.31 and 0.63 +/- 0.16 mm/sec, respectively. In the capillary the times from the R-wave to the minimicronm and maximum values were variable. In some cases the velocity gradually increased without first decreasing and the increase sharply accelerated a certain time after the R-wave. The mean velocity in the pulmonary capillary and the amplitude of the pulsatile flow ere 1.78 +/- 0.31 and 0.37 +/- 0.12 mm/sec, resepctively. The ratios of the pulsatile amplitude to the mean velocity in the pulmonary capillary, venule and arteriole averaged 0.21, and 0.36, respectively.

Animals↗
PubMed1979

A new needle-type colloid osmometer for continuous determination of blood oncotic pressure.

For the purpose of facilitating measurement of colloid osmotic pressure of body fluids, a new needle-type colloid osmometer which uses a hollow fiber as a semipermeable membrane instead of a sheet ultrafilter was developed. The simple construction, easy production, and satisfactory performance of the osmometer are described in detail. Although hydrostatic pressure existing in the sample interfered a little with the accuracy of measurement, quickly interchangeable sensing probes brought great advantages in practice.

Animals↗
PubMed1979

Non-uniform oxygen supply to the left ventricular myocardium by systolic perfusion of coronary artery.

The left anterior descending branch of the coronary artery (LAD) of anesthetized, open-chest dogs was perfused by intraventricular pressure (systolic perfusion) and aortic blood pressure (aortic perfusion) alternately. When the LAD perfusion was switched from aortic perfusion to the systolic one, the subendocardial PO2 decreased to 9.8 mmHg, on an average, in 1 to 2 min from the initial level of 18.9 mmHg obtained during the aortic perfusion. On total occlusion of LAD, the subendocardial PO2 fell to 4.5 mmHg, while the subepicardial PO2 showed no significant change. These results suggest that a small amount of oxygen is transported to the subendocardium during the systolic phase despite the impaired blood flow to the subendocardium and that the oxygen supply to subepicardium can be supported even though the LAD perfusion is restricted to the systolic phase.

Animals↗
PubMedDate not supplied

Epiretinal membrane formation in Terson syndrome.

Clinical features of epiretinal membranes were examined in 22 eyes of 13 patients with Terson syndrome who were treated with pars plana vitrectomy. The shape and localization of the epiretinal membranes were intraoperatively evaluated and correlated with the presence or absence of posterior vitreous detachment (PVD). Patients with complete PVD, but with no membrane found during surgery, were followed postoperatively. Membrane formation ultimately developed in 13 of the 22 eyes. In eight eyes, PVD was incomplete and the epiretinal membrane was found at the optic disc or along the temporal vascular arcades, displaying retinal folds and vascular tortuosity. Three eyes had massive tractional retinal detachment; five of those with complete PVD developed a thin epiretinal membrane around the posterior pole that became more apparent during long-term follow-up. From these observations, we can classify epiretinal membrane formation in Terson syndrome into two groups: with complete, or with incomplete, PVD. It also appears that multiple pathological processes involving the vitreoretinal interface were responsible for the formation of epiretinal membranes.

Adult↗
PubMedDate not supplied

Rat epididymal sperm motion changes induced by ethylene glycol monoethyl ether, sulfasalazine, and 2,5-hexandione.

Epididymal sperm was examined using the Hamilton-Thorne Sperm analyzer (HTM-IVOS, version 10.6) in male rats treated with known male reproductive toxicants that act by different mechanisms to detect effects on sperm motion. Three agents known to produce changes in sperm motion at high exposure levels were administered at lower levels. Ethylene glycol monoethyl ether (EGEE), sulfasalazine (SASP), and 2,5-hexandione (2,5-HD) were administered by oral gavage to adult male Sprague-Dawley rats at 250 or 500 mg/kg/day, at 300 or 600 mg/kg/day, or at 100 or 250 mg/kg/day, respectively. The males were treated with EGEE, SASP, and 2,5-HD for 35, 28, and 28 days, respectively. The males treated with EGEE and SASP were mated with untreated females to assess male fertility. All males were examined for body weight, testicular and epididymal weight, epididymal sperm count, and sperm motion. The sperm motion parameters included percentage of motile sperm, percentage of progressively motile sperm (progressive motility), curvilinear velocity (VCL), average path velocity (VAP), straight line velocity (VSL), amplitude of lateral head displacement (ALH), beat cross frequency (BCF), linearity (LIN), and straightness (STR). For the male rats treated with SASP, no treatment-related effects on percentages of motile sperm or sperm count were observed despite impaired male fertility. However, abnormal motion of epididymal sperm from the SASP treated males was detected by a significant reduction in mean progressive motility, VAP, and ALH, and an increase in BCF and STR. For the males treated with 2,5-HD for 4 weeks, most parameters generated by the HTM-IVOS indicated decreased sperm motion despite no remarkable changes in testicular weight, epididymal weight, or sperm count. In the EGEE-treated males at 250 mg/kg/day for 5 weeks, abnormal motion of epididymal sperm was detected by decreased progressive motility and increased BCF, although there were no treatment-related effects on testicular weight or male fertility. Progressive motility was decreased in all treated groups and the difference from the control value was of the greatest magnitude among the sperm motion parameters generated by the HTM-IVOS. Velocity parameters (VAP, VSL, VCL) responded sensitively to abnormal sperm motion in the SASP and 2,5-HD studies. In spite of decreased sperm motion, BCF values were significantly increased in all treated groups except the 7-week EGEE high-dose group, where there were no motile sperm to evaluate. ALH was significantly decreased in the treated groups in which remarkable effects on sperm motion were noted. There were no significant changes in ALH at the low-dose of EGEE at which only mild effects on sperm motion were observed. STR was increased for epididymal sperm from the males treated with SASP when compared with the controls. For the males treated with EGEE and 2,5-HD, however, STR was decreased when compared with the controls. There were no significant differences in LIN in any of the groups treated with SASP, in which remarkably reduced sperm motion was detected by the other parameters. In conclusion, among the parameters generated by the HTM-IVOS, progressive motility was significantly decreased in all treated groups and the most valuable for detecting slight changes in sperm motion induced by these three different target toxicants. Further investigation with a larger set of compounds is needed to evaluate which IVOS parameters are the most sensitive in detecting motion changes.

Animals↗