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Biomedical subjects

A Takeuchi

Publications and source records attributed to A Takeuchi.

At least 487 records · Page 27Linked to original sources
PubMed1980

The inhibitory effect of pregnancy serum on polymorphonuclear leukocyte chemotaxis.

The influence of pregnancy serum on the directional migration of normal human polymorphonuclear leukocytes (PMN) in response to a standard chemotactic attractant was studied. Using the Boyden chamber method for quantitating directional migration, both gestational and control sera in the unmodified state were found to have comparable actions on neutrophil chemokinesis and chemotaxis. Activation of these sera with endotoxin generated equivalent amounts of chemotactic factors. However, pregnancy serum in direct contact with normal PMN, inhibited their response to a standard chemoattractant (p less than 0.001). The suppressive effect was present in sera obtained during the third trimester of gestation. Sera obtained one month post partum contained less of the inhibitor of PMN directional migration. Since neutrophils are essential to the development of rheumatoid arthritis and certain other inflammatory diseases, the subsidence of these disorders during gestation and their exacerbation post partum could be related to the inhibitory effects of pregnancy serum on leukocyte functions.

Arthritis, Rheumatoid↗
PubMed1979

Formation of topographic maps and columnar microstructures in nerve fields.

Topographic connections are found in many parts of the vertebrate nervous systems, known for example as retinotopy. The self-organizing ability of Hebb type modifiable synapses plays an important role in forming, at least in refining, the topographic connections. We present a mathematical analysis of a revised version of the Willshaw-Malsburg model of topographic formation, solving the equations of synaptic self-organization coupled with the field equation of neural excitations. The equilibrium solutions are obtained and their stability is studied. It is proved that two cases exist depending on parameters. In one case, the smooth topographic organization is obtained as a stable equilibrium of the equations. In the other case, this solution becomes unstable, and instead the topographic organization with columnar microstructures appears. This might explain the columnar structures in the cerebrum. The theory is confirmed by computer simulated experiments.

Computers↗
PubMed1979

Purulent rectal discharge associated with a nontreponemal spirochete.

A nontreponemal spirochete was isolated from the rectum of a homosexual man with a chronic purulent discharge. Known infectious causes of the disease were excluded. Although the pathogenicity of the organism was not proved, the patient's symptoms rapidly resolved following penicillin G benzathine therapy. When culture of a nonhemorrhagic, purulent rectal discharge fails to verify Neisseria gonorrhoeae, health care personnel are encouraged to carefully examine a Gram's-stained smear of the discharge for spiral-shaped organisms.

Adult↗
PubMed1979

An analysis of the inhibitory post-synaptic current in the voltage-clamped crayfish muscle.

1. Inhibitory post-synaptic currents (i.p.c.s) were recorded from the feed-back current through a wire electrode inserted longitudinally into the opener muscle fibre of the claw in the crayfish (Cambarus clarkii). 2. I.p.s.c. rose to its peak in about 3-4 msec and decayed approximately exponentially. The decay time constant at -100 mV was 9.4 msec. 3. The decay time constant decreased as the membrane was hyperpolarized and increased during depolarization. The time constant (tau) depends on voltage (V) according to the relation tau = a exp (AV), with a = 18.6 msec and A = 0.0065 mV-1. Voltage dependence was opposite in direction to that seen at frog end-plates, but in the same direction as that of e.p.s.c. in crayfish muscle. 4. At lower temperatures, the rise and fall times of i.p.s.c.s were prolonged. Q10 for the decay time constant was 2.4 between 22.6 and 12.5 degrees C. 5. When pH was decreased from 7.2 to 5.5, the decay time constant increased by about 50%, with little change in the voltage dependence of the time course. 6. When chloride in the solution was changed to iodide, the decay time constant was increased by a factor of 3, while voltage dependence of the time course was not changed. In bromide solution the decay time constant increased by about 50%. 7. Peak amplitudes of i.p.s.c.s were approximately linear as the membrane was depolarized, but they levelled off as the membrane was hyperpolarized beyond reversal potential. The non-linear I-V relation did not result from inadequate voltage clamping, nor from a change in the inside concentration of chloride. After equilibration with iodide solution the I-V relation was approximately linear. 8. The decay time constant was increased after repetitive nerve stimulation. This prolongation became more pronounced at lower temperatures. 9. The kinetic process of the transmitter action is discussed. It is suggested that the rate limiting process for i.p.s.c. is binding and unbinding of the transmitter to the receptor.

Animals↗
PubMed1979

Cellular augmentation of polymorphonuclear leukocyte chemotaxis.

The density of neutrophils influences the number of cells that will respond to a chemoattractant, endotoxin-activated serium. When fewer than 3 x 10(5) polymorphonuclear leukocytes (PMN) were placed in the top compartment of a modified Boyden chemotaxis chamber, the cellular response was weak. Complete membrane penetration by activated neutrophils rarely was observed. When this number of PMN was exceeded, however, both the number of cells and the percentage of neutrophils responding to the leukoattractant increased. The density of cells required for effective chemotactic response to occur was such that intimate cell-to-cell contact was suggested. This indicated that PMN exerted a kinetic influence upon one another. Extracts of disrupted PMN induced an otherwise insufficient number of neutrophils to respond to the chemotactic stimulus. The active component was isolated in the cytoplasmic fraction (postcentrifugation, 100,000 x g, 60 min) of PMN, but was not present in other subcellular fractions. This cytoplasmic augmentor of chemotaxis (CACh) increased random mobility of neutrophils, but was not, itself, a chemotactic factor. These findings suggest that PMN cooperate in their response to a leukotactic stimulus.

Cell Count↗
PubMed1979

Spontaneous cryptosporidiosis in an adult female rabbit.

An asymptomatic adult female rabbit had intestinal cryptosporidiosis. The ileum had blunted villi, a decrease in villus-crypt ratio and a mild edema in the lamina propria. Transmission electron microscopy showed the parasite to be a Cryptosporidium similar to those reported in mouse, guinea pig, lamb, calf, horse, monkey and man. This organism is referred to as Cryptosporidium cuniculus. Scanning electron microscopy on ileal mucosa showed altered intestinal microvilli in the attachment of the cryptosporidia. It is postulated that the organism was enveloped by the microvilli of the ileal epithelial cells which then fused and formed a continuous double membrane around the parasite.

Animals↗