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Biomedical subjects

M Maeda

Publications and source records attributed to M Maeda.

At least 1,585 records · Page 88Linked to original sources
PubMed1976

In vitro differentiation of Rauscher-virus-induced myeloid leukemia cells.

Three cell lines were established in vitro from myeloid leukemias of C57Bl/6 strain mice which had been inoculated with Rauscher virus at birth. The use of heated conditioned medium from peritoneum proved helpful for the initial growth of leukemic cells. At early in vitro passage levels, cell line R433 differentiated only to macrophages after contact with conditioned medium from peritoneum but it appeared to have lost the ability to differentiate during an extended period of cultivation. Cell line R448 was cytologically promyelocyte. When exposed to conditioned medium, this cell line differentiated only to neutrophilic granulocytes. Cell line R453 maintained the ability to differentiate either to neutrophilic granylocytes or to macrophages. Single cells recloned three times still gave rise to both types of mature cells containing conditioned medium. Occasional cases of "spontaneous" differentiation in clonal lines of R453 also occurred.

Animals↗
PubMed1976

Determination of benomyl and 2-(4-thiazolyl) benzimidazole in plant tissues by high-performance liquid chromatography using fluorimetric detection.

Methods for determining benomyl [methyl 1-(butylcarbamoyl)-2-benzimidazole carbamate] residues in plant tissues involve isolation of the residue by extraction with ethyl acetate, hydrolysis of the extracted residue to 2-aminobenzimidazole and final determination by high-performance liquid chromatography using a fluorimeter. 2-(4-Thiazolyl) benzimidazole is also determined by a similar procedure without hydrolysis. The sensitivities of these methods are 0.02 ppm for benomyl and 0.001 ppm for 2-(4-thiazolyl) benzimidazole. Recoveries of these compounds from various plant tissues were 90.5-102.9%. No interference with these methods from the plant tissues tested was found.

Benomyl↗
PubMed1976

The effects of stimulating the cerebellar nodulus in the cat on the responses of vestibular neurons.

In a first series of experiments, recordings were obtained from cat abducens and trochlear motorneurons and from axons of secondary vestibular neurons terminating in these motor nuclei, and the effects of cerebellar nodulus stimulation on utricular- and canal-evoked responses in these neurons were studied. Ultricular activation of vestibular axons recorded in the ipsilateral VIth and contralateral IVth nuclei was probably monosynaptically inhibited by nodular stimulation provided conditioning-test intervals were in the range between 0-10 ms and the test stimuli were close to threshold intensities. Of the vestibular axons activated by stimulation of the semicircular canal nerves only those evoked by the horizontal canal stimulation and recorded in the ipsilateral VIth nucleus were weakly inhibited. When the vestibular stimuli were strong enough to produce clear field potentials in the motor nuclei and/or postsynaptic potentials in motorneurons, nodular stimulation had practically no effect on their amplitudes. It is concluded that inhibition of vestibuloocular transmission is weak as compared to floccular inhibition studied previously. In a second series of experiments, recordings were obtained from vestibular neurons which were activated antidromically and/or transsynaptically by stimulation of the contralateral fastigial nucleus, and the effects of ipsilateral nodular stimulation on these responses were studied. It was found that nodular stimulation inhibited both antidromic as well as transsynaptic fastigial activations of vestibular neurons. Most of these vestibular neurons were located in the descending vestibular nucleus and received polysynaptic vestibular and spinal inputs. It is concluded that in addition to its weak inhibitory effect on vestibuloocular transmission the nodulus exerts a powerful inhibition on vestibular neurons transmitting vestibular and spinal inputs to cerebellar nuclei and/or cortex. It is suggested that the nodulus controls cerebellar projecting vestibular neurons which carry vestibular and spinal information to the cerebellum. The vestibular, proprioceptive and visual information which is present in the nodulus may aid the role of the nodulus in controlling body posture.

Abducens Nerve↗
PubMed1976

Extracellular nuclease produced by a marine bacterium. I. Extracellular deoxyribonuclease formation by a marine Vibrio sp.

Deoxyribonuclease (DNase) activity was found in the culture fluids of numerous marine bacteria isolated from seawater. Among these ogranisms, marine bacterium, Vibrio sp., strain No. 2, showed the highest deoxyribonucleic acid-hydrolyzing activity. This organism requires salts of seawater for both growth and extracellular DNase formation. The DNase activity could not be detected in the synthetic seawater culture liquid lacking magnesium ion, and DNase activity decreased in a calcium-deficient medium. The optimum temperature for the growth of this organism was between 15 and 25 degrees C. The formation of extracellular DNase was the greatest at 20 degrees C and less activity was found at 10 and 30 degrees C.

Culture Media↗
PubMed1976

Extracellular nuclease produced by a marine bacterium. II. Purification and properties of extracellular nuclease from a marine Vibrio sp.

Extracellular nuclease produced by a marine Vibrio sp., strain No. 2, was purified by salting out with ammonium sulfate and by chromatography on a DEAE-cellulose column and twice on a Sephadex G-200 column. The nuclease was eluted as a single peak in which the deoxyribonuclease (DNase) activity and ribonuclease (RNase) activity appeared together. Polyacrylamide disc gel electrophoresis showed a single band of stained protein which had both DNase and RNase activity. The molecular weight of the enzyme was estimated to be 100 000 daltons. When using partially purified enzyme from the DEAE-cellulose column, the optimum pH for activity was 8.0, and the enzyme was activated strongly by 0.05 M Mg2+ ions and stabilized by 0.01 M Ca2+ ion. These concentrations of Mg2+ and Ca2+ ions are similar to those of the two cations in seawater. Indeed, the enzyme revealed high activity and strong stability when kept in seawater. The presence of particulate matter, such as cellulose powder, chitin powder. Hyflosupercel, Kaolin, and marine mud increased the stability of the enzyme. When the hydrostatic pressure was increased from 1 to 1000 atmospheres, the decrements of the enzyme activity were more pronounced at 30 and 40 degrees C than at 25 or 50 degrees C. The enzyme activity was restored after decompression to 1 atm at 30 degrees C.

Calcium↗
PubMed1976

Mossy fiber neck and second-order labyrinthine projections to cat flocculus.

In five decerebrate cats and in two under N2O-O2 anesthesia, a bipolar electrode array was inserted into a granular layer in the rostral flocculus. At this location MF field potentials were evoked by stimulation of the ipsilateral vestibular nerve and of the C2 dorsal root ganglion. Stimulation through the array was used to fire brain stem neurons antidromically. The activity of these neurons was recorded extracellularly with glass microelectrodes. Stimulation of the C2 dorsal root ganglion evoked in the caudal lateral brain stem a field potential caused by the arrival of impulses in primary afferent fibers. Cells projecting to the flocculus also responded to the stimulus, usually monosynaptically. These neurons were fired by stimulation of the area of the atlantoaxial joint. They did not respond to stimulation of the contralateral C2 dorsal root ganglion, and responded only rarely to stimulation of the dorsal rami of the C2 and C3 spinal nerves. Stimulation of the vestibular nerve was ineffective. Another group of cells projecting to the flocculus was fired at short latency by stimulation of the ipsilateral vestibular nerve. These neurons were usually inhibited by stimulation of the contralateral vestibular nerve. They were not affected by stimulation of any neck afferents. The location of many recording locations was identified by means of fast green dye marks. Most neurons relaying neck activity were in group x of Brodal and Pompeiano (4), a few were in the external cuneate nucleus, and one was in the descending vestibular nucleus. Neurons relaying labyrinthine activity were in the descending vestibular nucleus; one was found in the medial nucleus, in which tracks were made only rarely. There are two parallel pathways relaying neck and labyrinthine activity to the flocculus. While they are separate at the level of the brain stem, they converge in the same rostral areas of the flocculus. The neck afferent information may be required for proper performance of the flocculus in eye-movement control.

Animals↗
PubMed1976

Changes in serum triiodothyronine, thyroxine, and thyrotropin during treatment with thyroxine in severe primary hypothyroidism.

Studies were performed on 40 patients with severe primary hypothyroidism, during treatment with varying doses of T4. Therapy was initiated with 50 mug/day and was continued for at least 2 months. Subsequent repeated increases of 25 mug/day were continued for at least 2 months until the serum TSH level was less than 10 muU/ml. Measurements of serum T4 and T3, RT3U, and serum TSH were carried out at monthly intervals. TRH tests were performed after TSH levels of less than 10 muU/ml had been attained and the dose of T4 had been maintained for at least 2 months. In most of the samples obtained during treatment with various doses of T4 (50-175 mug/day), serum T4 concentrations were within the normal range, even when patients were receiving only 50 mug/day of T4; however, approximately 60% of the samples had subnormal T3 concentrations. Fifty per cent of the samples had elevated TSH concentrations despite normal T4 levels, while only 7% of the samples with normal T3, as well as T4, levels had slightly elevated TSH concentrations. Similar relationships were observed between serum TSH and free T4 indices and free T3 indices. Among patients with serum TSH levels of less than 10 muU/ml, none showed subnormal T4 concentrations, while subnormal T3 concentrations were found in some of them. Hyper-response to TRH was noted in patients with subnormal T3 levels, and normal responses were observed in patients with normal T3 and T4 concentrations. These data indicate that, during the treatment of hypothyroidism with T4, 1) normal basal TSH correlates better with normal serum T4 and T3 than with normal T4 alone, 2) the response of TSH to TRH is supranormal in patients with subnormal T3 levels, in spite of normal basal TSH and T4, and 3) the calculated maintenance dose of T4, which is associated with a normal TRH response, is 2.08 mug/day/kg of body weight.

Adult↗