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Biomedical subjects

A Ishida

Publications and source records attributed to A Ishida.

At least 19 recordsLinked to original sources
PubMed1992

Activity of primate putamen neurons is selective to the mode of voluntary movement: visually guided, self-initiated or memory-guided.

The aim of this report was to investigate the neural processes of movement initiation and control in which the basal ganglia play an essential role. Single-neuron activity was recorded in the putamen of monkeys performing learned arm movements initiated in three different modes: sensorially guided, internally-timed self-initiated and memory guided. There were no significant differences in the magnitude and timing of both prime mover and supporting muscle activity between the three modes of movement. Over half of the task-related neurons showed strong activity in one of the three modes of movement initiation, but were only slightly activated in the other two modes. No clear preference for a particular movement mode was evident in the population of putamen neurons as a whole. These results are consistent with the hypothesis that there are heterogeneous groups of neurons in the putamen, and that each group of neurons participates in retrieving a different kind of information required for movement based on either external sensory events or on internally stored information.

Animals↗
PubMed1992

Administration of milk from cows immunized with intestinal bacteria protects mice from radiation-induced lethality.

Oral administration of "immune milk", that had been obtained from cows immunized with a variety of human gut bacteria containing E. coli, S. typhimurium, S. dysenteriae and 23 others, protected AKR/J mice from the lethal effect of radiation, when immune milk was orally given to mice at 150 g kg-1 day-1 for 7 days prior to gamma-irradiation of 8 Gy. Mean survival times were 24.8 days for the group given immune milk but only 16.8 days for the group given control milk from unimmunized cows. Enterobacteriaceae were detected in various organs such as liver, lung and kidney on day 13 after irradiation, whereas the numbers were significantly fewer in the study group as compared with the control group. And fewer number of intestinal Enterobacteriaceae were detected in the study group compared with the control group prior to irradiation. Immune milk also enhanced the mitogenic response to mesenteric lymph node cells, the redirected cytolytic activity of intestinal intraepithelial lymphocytes to P815 tumor cells with anti-CD3 mAb, and in vitro killing activities of the phagocytes in mesenteric lymph nodes to E. coli as compared with control milk. These results suggest that immune milk may reduce the number of bacteria translocating from the intestinal-tract and augment the activities of the gut-associated lymphoid tissues against the invasion of intestinal bacteria, causing protection against the lethal effect of radiation.

Animals↗
PubMed1992

Ischemia-induced changes in PIP2 levels of gerbil hippocampus.

We carried out an immunohistochemical study to detect changes in phosphatidylinositol 4,5-bisphosphate (PIP2) in gerbil hippocampus at various times after transient ischemia, using an anti-PIP2 antibody. About 24 h after transient ischemia for 5 min, an increase in the immunoreactivity was observed which was restricted to the area of CA1 pyramidal neurons. On the other hand, after less severe ischemia lasting 2 min, which did not lead to neuronal death, a decrease in PIP2 immunoreactivity was observed at about 48 h. The results indicate that levels of PIP2 following ischemia reflect dynamic changes in phosphatidylinositol (PI) turnover which may be related to neuronal degeneration.

Animals↗
PubMed1992

Consumption of milk from cows immunized with intestinal bacteria influences age-related changes in immune competence in mice.

Milk was obtained from nonimmunized cows and cows immunized with a mixture of various human gut bacteria. Each milk was administered orally to 2-mo-old C57BL/6 mice at a dose of 150 g.kg-1.d-1 for either 6 or 16 mo. The study group had fewer enteric bacteria and a lower concentration of the serum antibodies against enteric bacteria compared with the control group at 8 and 18 mo of age. Furthermore, the study group at 18 mo old had a higher redirected cytotoxicity of intestinal intraepithelial lymphocytes, a higher proliferative response of mesenteric lymph nodes cells against mitogenic or alloantigenic stimulation and a greater ability of the spleen cells to produce anti-sheep erythrocytes IgG antibody after systemic immunization with sheep erythrocytes. A lower level of autoantibodies was observed at 8 mo and 18 mo of age in the study group compared with the control group. These results suggest that the senescence of the murine immune system may be delayed by consumption of milk from immunized cows.

Animals↗
PubMed1992

Study of the effect of 350-Hz tone exposure on electrophysiological function of the inner ear of guinea pigs.

The effects of noise exposure were studied in fifty-nine 4- to 5-week-old albino Hartley guinea pigs with normal hearing (body weight 250-300 g). The following experiments and results were carried out: exposure to 350 Hz pure tones at 115 dB for 40 h and exposure to 350 Hz tones at 120 dB for 64 h. In order to investigate the effects of low-frequency tone exposures on the hearing of the guinea pigs, cochlear microphonics (CM), whole nerve action potentials (AP) and endocochlear potentials (EP) were measured. With a high-sound pressure, a decrease was observed in the CM maximum output voltage in the test frequencies of 2, 4 and 6 kHz while the CM threshold (pseudothreshold) of 6 kHz was elevated. Output voltage of the N1 potential of the AP using a 7-kHz tone burst decreased while the threshold of the N1 potential was elevated. An extension of latency and a decrease in the absolute value of the negative potential in EP were also observed.

Acoustics↗
PubMed1992

Recurrent hemoptysis due to aortobronchopulmonary fistula of false aortic aneurysm associated with repair of rupture of the sinus of Valsalva.

A 54-year-old man presented with recurrent hemoptysis of one year duration. Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated a saccular aneurysm of the ascending aorta. The aneurysm was intraoperatively found to have formed on the superior surface of the site of aortotomy suture placed during previous repair of rupture of the sinus of Valsalva and to have a fistulous communication to the lung. CT and MRI were very useful in the diagnosis of the aneurysm as the cause of hemoptysis.

Aortic Aneurysm↗
PubMed1991

Failure of T cell receptor V beta negative selection in murine intestinal intra-epithelial lymphocytes.

The intestinal intra-epithelial lymphocytes (IEL) are divided into several subsets on the basis of expression of T cell receptor (TCR) alpha beta and gamma delta, intensity of Thy-1 expression and expression of Lyt-3 chain. To investigate the differentiation pathway of the IEL, we examined the repertoire of V beta segments of T cells in the IEL in BALB/c (H-2d, MIs-1b2a) or AKR/J (H-2k, MIs-1a2b) mice. Among freshly isolated IEL, an appreciable number of T cells bearing V beta 3 or V beta 11, which recognize MIs-2a- or MHC IE-encoded molecules respectively, were detected in BALB/c mice. Similarly, in AKR/J mice, IEL contained appreciable levels of V beta 6-bearing T cells. V beta 3- or V beta 11-bearing T cells in the IEL in BALB/c mice increased to a significant level when incubated with staphylococcal enterotoxin A which specifically stimulates V beta 3- and V beta 11-bearing T cells. Most of IEL without clonal deletion expressed Lyt-2 but not Lyt-3 antigens. Such T cells were hardly detected in other organs, including liver. Our results indicate that TCR alpha beta-bearing intestinal IEL that have not undergone negative selection may have differentiated outside the thymus, presumably at a local site of the intestine and can respond normally to the signal via their TCR.

Animals↗
PubMed1991

Sequential appearance of T-cell receptor gamma delta- and alpha beta-bearing intestinal intra-epithelial lymphocytes in mice after irradiation.

We have previously reported that T-cell receptor (TcR) gamma delta-bearing T cells precede TcR alpha beta-bearing T cells in appearance in the thymus after whole-body irradiation. In the present study, the kinetics of appearance of intestinal intra-epithelial lymphocytes (IEL) was examined in mice after whole-body irradiation with a lethal dose of 9.5 Gy or with a sublethal dose of 6 Gy. The number of CD3+ IEL decreased to the lowest value 4 days after irradiation with 9.5 Gy, and thereafter increased to half as many as the normal level by day 7. Thy-1+TcR alpha beta- IEL and Thy-TcR alpha beta- IEL recovered considerably by day 7 after the irradiation, whereas Thy-1+TcR alpha beta+ IEL and Thy-1+TcR alpha beta+ IEL hardly recovered at this stage. All mice died within 12 days after irradiation with a lethal dose of 9.5 Gy. On the other hand, when irradiation dose was decreased to 6 Gy, all mice survived beyond 40 days after irradiation. The number of CD3+ IEL recovered to the normal level by 10 days after irradiation with 6 Gy. Consistently with the results in mice irradiated with a lethal dose, the first cells to increase in IEL of mice irradiated with a sublethal dose were TcR gamma delta+ IEL expressing Thy-1 antigen. The number of Thy-1+TcR gamma delta+ IEL increased to approximately two-fold as many as that in normal mice by day 10, while TcR alpha beta+ IEL began to increase in number from day 20 after irradiation and recovered to the normal level by day 40 after irradiation. Thus, sequential appearance of TcR gamma delta+ and TcR alpha beta+ IEL was evident after irradiation, similar to that seen in the thymus after irradiation. The IEL on day 10 after a sublethal irradiation, which is composed mainly of Thy-1+TcR gamma delta+ IEL, exhibited a strong cytolytic activity against P815 in the presence of anti-CD3 mAb, suggesting that the early appearing Thy-1+TcR gamma delta+ IEL may play important roles in epithelial immunity at an early stage after irradiation.

Animals↗
PubMed1979

Intracellular distribution of calcium in cardiac muscles studied by electron microscope autoradiography.

The intracellular distribution of calcium was investigated by 45Ca electron microscope autoradiography in the frog or rat ventricular muscle and guinea pig papillary muscle. The muscle was incubated for 30 min in 45Ca-Ringer's solution or high Ca solution in which 1/10--1/20 of Ca was replaced with 45Ca. The distribution of developed silver grains sensitized by the 45Ca (45Ca grains) was found to be 38% in the mitochondria, 43% in the myofibrils and 19% in the other regions (8% in the cytoplasma and 11% in the various membranous structures) in the frog muscle cell incubated in the 45Ca-Ringer's solution. After electrical stimulation (10 Hz, 5 min), the distribution was 22% in the mitochondria, 53% in the myofibrils and 25% in other regions. Similar results were obtained after high K stimulation in the frog ventricular muscles and after electrical stimulation in high Ca solution in guinea pig papillary muscles. Following the addition of 1 X 10(-6) g/ml adrenaline into the incubating solution, the grain distribution in guinea pig papillary muscles did not show significant change but the distribution in myofibril decreased after electrical stimulation, while it increased in the mitochondria. Longitudinal localization of 45Ca grains along the myofibril was also examined and it was a general tendency throughout all animals examined that the grain density at the A band and near the Z band decreased after electrical stimulation, while it increased at the I band and, especially, at the A-I junction.

Animals↗
PubMed1978

Binding of 45Ca to intercalated discs of cardiac muscles studied by electron microscope autoradiography.

The binding sites of Ca2+ entering the injured cardiac muscle cell was investigated by 45Ca electron microscope autoradiography in guinea pig papillary muscle and in frog ventricular muscle. The muscle was injured in Ca-free Tyrode's solution, transfered into 45Ca-Tyrode's solution and, after 30 min, fixed and cut into thin sections. An autoradiogram was taken after exposure (4--7 weeks) the thin film of the section was developed. Fine, or sometimes filamentous, silver grains produced by radiation with 45Ca were frequently observed on the intercalated discs of injured cells where most of the nexal membranes were separated. The number of 45Ca grains on the discs of injured cells was eight times more than that found on intact cells. The concentration of 45Ca grains estimated by the number of grains per unit area was 3.2 times higher in the disc region than that in the other cytoplasmic regions in the injured cells, while in the intact cells it was only 1/3 of that found in the latter. The localization of 45Ca grains along the disc of the injured cell was also examined and the fine grains were seen to be located on the separated nexal membrane or at the cytoplasmic side of the desmosome and fascia adherens. It is likely that Ca2+ binds with the nexal membrane and the resulting structural change, such as nexal separation, is indispensable for intercellular uncoupling or healing-over of cardiac muscles.

Animals↗