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Biomedical subjects

T Mikami

Publications and source records attributed to T Mikami.

At least 667 records · Page 37Linked to original sources
PubMed1982

Gelatin of Limulus amoebocyte lysate by simple polysaccharides.

The Limulus lysate gelatin activity of several simple polysaccharides including yeast mannans and bacterial dextrans was investigated. The mannans from Saccharomyces cerevisiae wild and mutant strains possessing dense branches showed positive gelatin activity at concentrations of 1 microgram/ml or more regardless of differences in their chemical structure. However, two synthetic mannans possessing linear structures with alpha 1 leads to 2 and alpha 1 leads to 6 linkages also gave positive reactions at concentrations of 10 microgram/ml or more and 500 microgram/ml or more, respectively. The dextran from Leuconostoc mesenteroides IAM 1046 consisting of a dense branching moiety displayed reactivity at concentrations of 100 microgram/ml or more, while the dextrans devoid of such branches were negative in this reaction. The optimal concentration for Limulus lysate gelatin could not be determined for any of the polysaccharides and lipopolysaccharides (LPS) tested in this study. The gelation activity of the polysaccharides was stable to treatment with 100 mM NaOH at 30 C for 72 hr. The minimum concentration for the gelation activity of LPS treated with 100 mM NaOH under the same conditions was reduced from 10(-6) approximately(-9) microgram/ml to 1-10 microgram/ml. The above findings demonstrate that the major part of Limulus lysate gelation activity of LPS depends on the alkali-degradable lipid A moiety, and that such simple polysaccharides are also able to participate in this activity even though the extent of participation is very low.

Alkalies↗
PubMed1982

Mitogenic effect of the mannans from Saccharomyces cerevisiae on mouse spleen lymphocytes.

The DNA synthetic activities of mannans isolated from two Saccharomyces cerevisiae strains were examined in vitro using spleen cells obtained from normal or nude BALB/c strain mice. A highly branched mannan isolated from the S. cerevisiae wild type strain induced a greater increase in mitogenic activity than those displayed by the mannan of the S. cerevisiae X2180-1A-5 mutant strain which possessed fewer branching moieties. Acid-hydrolyzed wild type strain mannan with two-thirds of the molecular weight of the parent intact mannan showed weak mitogenicity. Increases in the DNA synthetic activities of nude and normal spleen cells were almost the same as that of wild type strain mannan, while nylon wool column-passed spleen cells obtained from both normal and nude mice did not show mitogenicity with this mannan. The results indicated that the mitogenic activity was responsible for the highly branched structure of the wild type strain mannan, and that this mannan is a B-cell mitogen.

Animals↗
PubMed1982

Dynamics of cardiac, respiratory, and metabolic function in men in response to step work load.

Stroke volume, heart rate, cardiac output, tidal volume, respiratory frequency, minute ventilation, end-tidal tensions of O2 and CO2, O2 uptake, CO2 output, and respiratory exchange ratio were measured simultaneously in healthy male volunteers before, during, and after upright bicycle exercise from 0 to 360 and 720 kpm/min. The circulatory variables were determined continuously once per 20 cardiac cycles and the respiratory variables breath by breath using separate computer-based systems in which an impedance pneumograph and an impedance cardiograph were incorporated. Stroke volume, heart rate, and cardiac output started to increase without measurable delay at the onset of exercise. Stroke volume increased by 20% from resting control value in response to the mildest exercise and essentially leveled off with a further increase in work load. Time constant for cardiac output increased with the increasing work load. Time constant for minute ventilation was much longer than that for cardiac output and independent of work intensity. A good synchronization between the ventilation and cardiac output responses at an initial period of transitions from rest to exercise and from exercise to rest seems to support the concept of cardiodynamic hyperpnea.

Adult↗
PubMed1982

Idiopathic mitral valve prolapse-analysis by real-time two-dimensional echocardiography.

Mitral valve prolapse is diagnosed in real-time two-dimensional echocardiograms when there are discrepancies in the coaptation zone of the anterior mitral leaflet and the posterior mitral leaflet. Out of the 100 cases of mitral valve prolapse diagnosed in this way, 65 had prolapsed anterior mitral leaflets, 28 prolapsed posterior mitral leaflets and 7 prolapses of both the anterior and posterior mitral leaflets. In addition to the cases with mitral valve prolapse 23 cases of ruptured chordae tendineae of the mitral valve, including 15 cases which had undergone surgery, were investigated. The frequent site of mitral valve prolapse was the posteromedial commissure in the anterior leaflet and the posteromedial and anterolateral commissures in the posterior leaflet. These sites coincide with those where rupture of the chordae tendineae of the mitral valve was apt to occur. An investigation of the relation between age and mitral valve prolapse showed that the number of cases of prolapsed anterior leaflet did not increase with age, but there was an age-related increase in the number of cases of prolapsed posterior leaflets. It was also found that the degree of the prolapse progressed with age. Many of the cases of ruptured chordae tendineae of the mitral valve were in their forties or fifties, and there appeared to be some relation between the progress of the prolapse and age. Mitral regurgitant murmurs were recorded on phonocardiograms, and the severer the degree, the wider the range of the prolapse. Mitral regurgitation was more likely to occur in cases of prolapsed posterior leaflets than in those with prolapsed anterior leaflets, even if the degree and the range of the prolapse were mild.

Adolescent↗
PubMed1982

The dynamic response of the cardiopulmonary parameters to passive head-up tilt.

Transitional changes in stroke volume, heart rate, and cardiac output resulting from head-up tilt were measured in healthy male subjects, using impedance cardiography. Respiratory frequency, tidal volume, ventilation rate, end-tidal O2 and Co2 tensions, O2 uptake, CO2 output, and exchange ratio were also determined breath-by-breath. When the subject was tilted upward from a supine to an upright position, the stroke volume was decreased while the heart rate was increased. The time required to attain the steady state was shorter in the stroke volume change than in the heart rate. In addition, since the heart rate was not increased so high as to be inversely related to the stroke volume, the cardiac output decreased by tilting upward. The ventilation rate remained almost unchanged within a tilt angle of 60 degrees or so. Thus, both the O2 and CO2 fractions in expired air showed transitory changes. As the original body position was restored, the cardiac output was increased to the initial level, the tidal volume showing a transient increase. During the recovery process, PCO2, in expired air increased and PO2 decreased, showing that the change in cardiac output exceeded that in ventilation in quantity. The change in ventilation moreover, preceded that of expired PCO2 by ca. 10 sec, suggesting that the enhancement of ventilation occurred through some agent(s) other than the chemical drive.

Adult↗
PubMed1982

[Pulsed Doppler echocardiography in a case of coronary artery-pulmonary artery fistula: analysis of flow pattern within the main pulmonary artery and detection of a small shunt].

Flow pattern within the main pulmonary artery was analysed by pulsed Doppler echocardiography in a case of coronary artery-pulmonary artery fistula. An asymptomatic 32-year-old female was referred to our hospital for evaluation of a continuous murmur in the second interspace at the left sternal border. Other physical findings, chest roentgenograms and electrocardiograms were normal. Two-dimensional echocardiography did not play an important role in the diagnosis. However, pulsed Doppler echocardiography revealed an antegrade turbulent flow along the antero-lateral wall of the main pulmonary artery from early diastole to early systole. The direction and distribution of this abnormal flow was judged to be different from that of patent ductus arteriosus. Coronary arteriography showed a fistula from the both coronary arteries to the proximal portion of the main pulmonary artery. However, its shunt was so small that it could not be detected by oxymetry or by hydrogen-platinum electrode method. This case suggests that Doppler method is very sensitive in shunt detection and possibly useful for non-invasive diagnosis of coronary artery-pulmonary artery fistula.

Adult↗
PubMed1982

An on-line computer system for monitoring respiratory and cardiac functions of patients.

A computer-based noninvasive and continuous patient monitoring system for breath-by-breath assessment of cardiorespiratory functions was developed. Transthoracic impedance changes caused by respiratory and cardiac activities were measured with separate impedance plethysmographs of different frequencies. A mini-computer system calculated on-line eight respiratory parameters (VT, f, VE, PETO2, PETCO2, VO2, VCO2, and R) in cooperation with expired gas analysis data from a mass-spectrometer, and three cardiac parameters (SV, HR and Q). These parameters were displayed simultaneously at the end of each breath. In order to improve the signal-to-noise ratio of the impedance cardiogram to a level allowing computer determination, an ensemble averaging technique was utilized. The computer-derived cardiorespiratory parameters obtained during voluntary hyperventilation and a passive tilt demonstrated reasonable changes.

Carbon Dioxide↗
PubMed1981

Enhancement of antibody activity to bovine leukemia virus by complement.

Cocultivation of fetal lamb kidney cells infected with bovine leukemia virus (BLV) and the cat cells containing murine sarcoma virus genome resulted in the rapid production of syncytia. This syncytia formation was inhibited by serum containing antibodies to glycoprotein antigen of BLV. When rabbit complement was added to the antiserum for early syncytia inhibition (ESI) test, a significant enhancement of ESI activity of the antiserum was observed. This enhancement was associated with IgG fraction but not with IgM fraction of the antiserum. The results of the comparative serological tests showed that the ESI test with complement was much more sensitive than either immunodiffusion or complement fixation tests in the detection of BLV antibodies.

Animals↗
PubMed1981

Induction of transformed phenotypes in sheep fibroblasts by culture fluids from cells persistently infected with bovine leukemia virus.

FLK cells are fetal lamb kidney cells persistently infected with bovine leukemia virus (BLV). 3178 cells, originating from calf-form bovine lymphosarcoma, also showed persistent production of BLV and alteration of cell morphology, after treatment with 5'-iodo-2'-deoxyuridine. In the present paper, the first in vitro transformation of sheep fibroblasts by inoculation with BLV materials from these two cell lines is described. In a few passages after inoculation with these viral materials, morphological alteration occurred. The morphologically altered cells were grown as stable cultures and showed such transformed phenotypes as growth in soft agar medium, increased uptake of 2-deoxy-D-glucose and tumorigenicity in athymic nude mice. This result, together with our previous observation of simultaneous induction of BLV expression and morphological alteration of 3178 cells, suggests the presence of some transforming capacity in these BLV materials similar to that in, for example, murine or avian acute leukemia viruses. The possible acquisition of such capacity during the prolonged passage is discussed.

Animals↗