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Biomedical subjects

M Aoki

Publications and source records attributed to M Aoki.

At least 793 records · Page 44Linked to original sources
PubMed1981

Dynamics of red cell egress from bone marrow after blood letting.

To study the dynamics of red cell egress from the marrow, the demand for red cell delivery was enhanced in splenectomized rats by removing 25% of the blood volume, which was then immediately replaced by plasma. Within 15 min, packed cell volume declined by 22% of the initial value. Corrected reticulocyte count followed a biphasic pattern: an initial peak amounting to 26% occurred within 4-6 h followed by a more marked peak after 48 h. Quantitative electron microscopy of the marrow sinus wall indicated significant increases in the numbers of reticulocytes and leucocytes in transit after 5 h. Vesicles containing a flocculant substance were seen in the endothelium. The vesicles could cause segmental destabilization of endothelium, providing suitable areas for cell migration. There was also a significant reduction in the mean length of the overlapping segments of the endothelial cells, suggesting that these cells slid over one another to increase the luminal calibre. Within the rigid confines of bones where the marrow volume is fixed, this increase may lead to the displacement of mature haemopoietic cells into the lumen and whence into the circulation.

Animals↗
PubMed1981

OTO method for preservation of actin filaments in electron microscopy.

Osmium tetroxide, commonly used as a fixative in electron microscopy, can destroy actin filaments. Thiocarbohydrizide (TCH) is a bipolar substance that binds to the osmium. By sandwiching TCH between two phases of osmium treatment, tissue exposure to osmium could be minimized without destroying actin filaments. The contrast of osmophilic components of cells was also enhanced.

Actins↗
PubMed1981

[Synergistic effect of thiamphenicol and cephalothin on Bacterioides fragilis (author's transl)].

Synergistic effect of thiamphenicol (TP) and cephalothin (CET) on Bacteroides fragilis was proved in vitro. Especially its effect was much clear on B. fragilis which is possible to produce beta-lactamase. Synergistic bactericidal effect of TP and CET was proved. Chemotherapeutic effect of TP and CET against experimental mixed infectious mouse due to E. coli (beta-lactamase -) and B. fragilis (beta-lactamase +) was proved.

Animals↗
PubMed1981

The causes of death of tuberculosis patients in chemotherapy era.

Detailed analysis was made on causes of death among tuberculosis patients hospitalized in national sanatoria and those registered as tuberculosis at the breath centres. Deaths directly or indirectly related to tuberculosis could be divided into the following four major categories; dying with active tuberculosis process shortly after the detection due to the delay in detection, with active process combined with the emergence of drug resistance long after the detection due to failure in treatment, with sequela of tuberculosis mainly cardiopulmonary insufficiency, and with other conditions listed as non-tuberculosis death but attributable to either active or inactive tuberculosis. The ratio of these four categories at present in Japan is estimated to be approximately 1:1:2:4-6. The results indicate that the magnitude of tuberculosis problem should not be underestimated through decline in the crude tuberculosis mortality.

Antitubercular Agents↗
PubMed1981

Red cell egress from bone marrow in state of transfusion plethora.

Marrow sinuses have been shown to undergo rhythmic dilatations and this has been suggested as a mechanism controlling cell egress from the marrow. Within the rigid frame of bone where the volume of the marrow is fixed, dilatation of sinuses can only lead to the displacement of cells into the lumen. The absence of tight junction between sinus endothelial cells is thought to permit the overlapping segments of these cells to slide over one another. To test this hypothesis, the length of overlapping segments between endothelial cells was measured before and after the induction of transfusion plethora and this was correlated with the magnitude of reticulocyte traffic across the sinus wall. Within one hour after the induction of plethora, marrow sinuses were dilated, packed with red cells, and the mean length of overlapping segments was reduced significantly from 0,75 micrometer to 0.41 micrometer. This was associated with a decline in the magnitude of reticulocyte transit across the wall (0.73 vs 0.13/mm). These observations are consistent with the theory that the overlapping segments of sinus endothelial cells can slide over each other to change the luminal caliber. Transfusion plethora results in a sustained maximal dilatation of sinuses, thus preventing their rhythmic changes necessary for cell delivery into the circulation.

Animals↗
PubMed1981

[An evaluation of fetal movement during non stress testing (author's transl)].

The measuring methods of fetal rolling movements, which are very important diagnostic informations at the case of Non Stress Test, are analysed. In normal pregnant women (from 29 to 40 gestational weeks), the observation of fetal head and trunk rolling movements by real-time B-scan, and maternal perception of fetal movements are simultaneously recorded in analog data recorder. Analysing these recorded data, we found that 76.7% of fetal rolling movements could be detected by observation of head rolling movements only, and 72.4% with trunk observation only. But maternal perception could find only 28.5% of fetal rolling movements. These results and analysis may suggest us that, if only one machine is available, the observation of fetal head rolling movements by real-time B-scan is the most effective method for the analysis if fetal rolling movements on NST.

Female↗
PubMed1980

Generation of spontaneous respiratory rhythm in high spinal cats.

Spontaneous respiratory neuronal activities within cervical spinal cord were investigated in two groups of 36 adult cats: cervical spinalized and non-spinalized preparations. In the first group of 18 animals, spontaneous breathing was abolished after total spinal transection at C1. However, spontaneous rhythmic breathing reappeared within 2 h after transection in 13 animals. In the other 6 animals spinalized at C3 level, we could not induce spontaneous breathing. The spinal respiratory movements were found to be mainly due to rhythmic diaphragmatic contraction. Such spinal respiratory activity continued for 30 min-1 h with a steady rate of 19-24/min and then they steadily deteriorated. Spinal respiratory activity developed usually without hindlimb muscle activity and even when hindlimb stepping rhythm was seen simultaneously, it was not locked to respiratory rhythmicity. During spinal respiration, phrenic motoneuron discharges were recorded from the C5-C6 ventral horn. The burst discharges containing 4.8-40.0 spikes were all in synchrony with the inspiratory phase of respiratory cycles. Even after breathing movements were temporarily paralyzed by gallamine, the rhythmic bursts still persisted for an appreciable time. In the second group of 12 lightly anesthetized cats, microelectrode explorations of the upper cervical cord were made in an attempt to record neuronal activities associated with respiratory movements. A total of 24 burst discharges of inspiratory type units which represent presumed cell body activities was recorded. The recording sites were histologically located in the intermediate zone of the spinal gray matter of C1-C2 cervical cord. These results suggested the possible existence of some intrinsic respiratory rhythm generators within the cervical cord. Possible neuronal mechanisms for generation of spontaneous respiratory rhythm were discussed.

Afferent Pathways↗
PubMed1980

Membrane fusion induced by the membrane mobility agent, A2C. Differentiation between fusible and non-fusible cells. Transfer of fusibility.

Red cells of different species respond differently to the treatment with the membrane mobility agent, A2C, with respect to both the A2C interaction and the subsequent cell-cell interaction. Depending on whether both, one or neither of the processes are effective, some red cells (e.g., nucleated Leghorn hen red cells, rat red cells) fuse easily, some (human red cells) show morphological changes but do not fuse, and others (nucleated Rock hen red cells) show little or no response. Mixed fusion (i.e., between fusible cells of different species) is readily obtained, indicating that no species-specific recognition sites are required for A2C-induced fusion. the potential for fusion is a transferable characteristic. In the presence of fusible cells, A2C induces both heterologous and homologous fusion of otherwise 'non-fusible' cells. Electron micrographs of fusing cells after treatment with A2C reveal 'onion-ring' structures ('whorls'), free of intramembranous protein particles but different from the smooth appearance of A(2)C particles. Whorls are considered to arise from fusion-potent membrane areas. Fusion is apparent at multiple sites along the contact line between apposed membranes. The postulated appearance of vesicle-like structures along the fusion line (Kosower, E.M., Kosower, N.S. and Wegman, P. (1977) Biochim. Biophys. Acta 471, 311-329) is confirmed by micrographs. The mechanism of this fusion process is duscussed and compared to other types of fusion process.

Animals↗
PubMed1980

Postinhibitory rebound facilitation of the extension reflex in the high spinal cat.

Neural mechanisms of the reflex rebound of the hindlimb were studied in the high spinalized cat. After the animal had recovered from spinal shock, a light touch-pressure on the foot pad elicited a rebound extension reflex of the ipsilateral hindlimb. Excitability changes in hindlimb motor nuclei during the rebound phenomenon were examined by recording test monosynaptic reflexes (MSR). During touch-pressure stimulation, flexors such as the biceps femoris and tibialis anterior were facilitated, while extensors such as the gastrocnemius and quadriceps femoris were inhibited. After cessation of a stimulus, extensor MSRs showed a rebound facilitation which lasted for a few seconds. The greater the preceding suppression of MSR, the greater the rebound facilitation. Membrane potential changes induced in extensor motoneurons by touch-pressure were investigated by intracellular recordings. In most of the motoneurons tested (21/24), a clear membrane hyperpolarization was observed during stimulation and was followed by a rebound firing on cesstion of stimulation. Possible mechanisms underlying the rebound extension reflex were discussed.

Animals↗