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Biomedical subjects

I Takeuchi

Publications and source records attributed to I Takeuchi.

At least 109 records · Page 6Linked to original sources
PubMed1986

Unusual apparent hyperchloremia induced by long-term abuse of bromide-containing drugs.

Recently, we have observed 8 cases showing unusually high serum chloride (Cl-) levels of 282, 279, 257, 251, 213, 169, 123 and 120 mEq/l respectively, as measured by the ion selective electrical method (ISE). All of these cases showed almost normal Cl- levels by the coulometric method. Five of the patients had been taking Bromide (Br-)-containing drugs for a long period, and were found to have high serum levels of Br- ranging from 0.6 to 11.0 mEq/l (normal level: 0.1 mEq/l greater than). The cause of this abnormal elevation in serum Cl- as measured by ISE was investigated as follows. First, normal human pooled serum was mixed with NaBr solution to give increasing concentrations of Br- ions, which was then analyzed using the ISE method. Results showed that the selective response ratio of Br- against Cl- had values as high as 15.03 with ISE in contrast to values of 1.0 obtained by coulometry. Secondly, 7 healthy volunteers were given 4 commercially obtained Br(-)-containing tablets (Sedes A; Shionogi & Co., Ltd.) every day for 8 days. Their mean serum Cl- values measured by ISE gradually increased from 108 to 112 mEq/l, paralleling increments of mean Br- value from 0.1 to 0.6 mEq/l over 9 days. From these observations, it is concluded that serum chloride values obtained by ISE are easily interfered with by Br-. Paradoxically, however, this fact is often a good indicator of Br- intoxication. The authors therefore recommend clinicians to pay more attention to the Br- intoxication that often occurs from overdosage of Br(-)-containing drugs, some of which are commercially available without prescription.

Adult↗
PubMed1985

Prestalk/prespore differentiation tendency of Dictyostelium discoideum cells as detected by a stalk-specific monoclonal antibody.

By the use of a prestalk- and stalk-specific monoclonal antibody, production of prestalk antigen was examined with non-glucose grown [G(-)] and glucose grown [G(+)] cells of Dictyostelium discoideum AX2. Unlike wild type (NC4), some growth phase cells of AX2 were reactive with the antibody. However, G(-) cells contained much more antigen than G(+) cells and the difference between the two remained during the preaggregation period. Besides glucose, the addition of metabolizable, but not nonmetabolizable sugars to both growth phase and preaggregation cells suppressed the production of the prestalk antigen on the one hand and stimulated the accumulation of glycogen on the other hand. When mixed, G(-) cells which produced more prestalk antigen during the preaggregation period remained prestalk cells after aggregation, while G(+) cells which produced less antigen were converted to prespore cells. G(+) cells collected at the stationary phase [G(+)st] were stronger in prestalk sorting tendency than G(+) cells but weaker than G(-) cells. The prestalk antigen content of G(+)st cells prior to aggregation was an intermediate between those of G(-) and G(+) cells. These lead to the conclusion that the prestalk antigen content of preaggregation cells reflect the tendency of the cells toward either prestalk or prespore differentiation after aggregation.

Animals↗
PubMed1985

Disaggregation-induced changes of developmentally regulated proteins in Dictyostelium discoideum.

By means of two-dimensional gel electrophoresis, we analyzed proteins present in a slug-shaped tissue mass of D. discoideum and examined the changes in their amounts after disaggregation of the slugs. Of approximately one hundred polypeptides, six were found to decrease in amount after disaggregation. The decreases of four polypeptides were inhibited by the presence of 1 mM cAMP or 250 micrograms/ml cycloheximide. The decreases of the two other proteins were not suppressed by cAMP or cycloheximide. The patterns of proteins present in vegetative and aggregative cells were also examined. None of the six proteins which showed a decrease after slug disaggregation was found in vegetative or preaggregative cells. These results indicate that both synthesis and degradation of these proteins are controlled by cell-cell contact.

Cell Aggregation↗
PubMed1985

The origin of prespore vacuoles in Dictyostelium discoideum cells as analysed by electron-microscopic immunocytochemistry and radioautography.

Prespore vacuoles (PSVs) are specifically formed in prespore cells of the cellular slime moulds and contain spore-specific antigens. We have examined the processes of PSV formation in Dictyostelium discoideum, using both the methods of immunoelectron microscopy with antispore serum and electron-microscopic radioautography with [3H]fucose, which is specifically incorporated into prespore cells. When prespore cells begin to differentiate at the late aggregation stages the Golgi apparatus, consisting of stacked cisternae and numerous vesicles, becomes conspicuous. Vesicles and flat sacs containing fibrous and membranous materials, respectively, are derived from Golgi cisternae. Spore antigens are found in these structures as well as in immature and mature PSVs. Fucose is incorporated into the same structures. When prespore differentiation is completed, the Golgi cisternae almost disappear and both antigens and fucose are localized in mature PSVs. The Golgi apparatus is scarcely observable in prestalk cells. Moreover, a similar pattern of changes in the Golgi apparatus and related structures occurs during the re-differentiation of prespore cells within prestalk isolates. It is concluded from these findings that PSVs are derived from the Golgi apparatus, the development of which is closely related to the differentiation of prespore cells.

Autoradiography↗
PubMed1985

A preliminary study on rabbit tubal anastomosis with the Nd-YAG laser.

This is the first report on the use of the Nd-YAG laser in performing tubal end to end anastomosis in rabbit. At first, the optimal intensity of laser exposure was evaluated using histological preparations of tubal ampullary tissues which were exposed in various conditions. It was determined that the most suitable condition was 12 watts/cm2 of energy density of 0.2 second duration and a 0.6mm focal spot. Subsequently, these treatment conditions were applied practically to end end anastomosis of severed tubal ampulla of three rabbits. Four weeks later, the second laparotomy was done to confirm the restoration of tubal patency by chromopertubation in vivo, and to excise the restored tube to study the reconstruction of luminal epithelium histologically by scanning electron microscope. Proven by chromopertubation in vivo, tubal patency was restored in 4 out of 6 tubal samples, but in two, tubes were dehisced at the anastomosed line. By scanning electron microscopic observation of tubal samples in which patency was restored some injury to mucosal epithelial cells was seen at the anastomosed site. It is concluded that the Nd-YAG laser technique is useful in tubal end to end anastomosis of rabbit and accurate placement of tubal stumps is essential to the proper restoration of tubal patency.

Animals↗
PubMed1983

Prestalk and prespore differentiation in Dictyostelium as detected by cell type-specific monoclonal antibodies.

Monoclonal antibodies specifically reactive against prestalk and prespore cells of the cellular slime mold Dictyostelium discoideum were obtained. By the use of these antibodies, we examined processes of differentiation of the two cell types during development. Cells stained with prespore-specific antibodies first appeared after 12-14 hr of starvation within cell aggregates with tips, coincidentally with the appearance of other prespore markers. The number of prespore cells then increased to a level of 70-80% of total cells at the slug stage. By contrast, cells stained with prestalk-specific antibodies began to appear after 3 hr of starvation and thereafter increased in number to a maximum of ca. 80% after 12 hr of starvation. Stained cells appeared at random in the aggregation field and were not morphologically distinguishable from unstained cells. Furthermore, cells showed a considerable heterogeneity in the amount of antigen they contain. Concomitantly with the increase in prespore cells, the number of cells stained by the prestalk antibodies decreased to a level of ca. 20% by the slug stage. From these experiments, we suggest that the prestalk antigen is synthesized in the majority of cells during the early period of aggregation. Within tight cell aggregates, some of these cells lose the antigen to become prespore cells and the normal proportion between the two cell types will eventually result within slugs.

Journal Article↗
PubMed1983

Purification and characterization of the extracellular cyclic AMP phosphodiesterase of Dictyostelium discoideum.

Extracellular phosphodiesterase for adenosine 3':5'-monophosphate [EC 3.1.4.17] was purified from the supernatant of aggregation phase culture of Dictyostelium discoideum, and two types (type I and type II) of the enzyme were found. The type I enzyme was not absorbed on DEAE-Sephacel at pH 8.5 and had an apparent molecular weight of about 67,000 daltons. In contrast, the type II enzyme was adsorbed on DEAE-Sephacel and had an apparent molecular weight of about 120,000 daltons. The Km values of the two types were similar (2-4 microM). Upon SDS polyacrylamide gel electrophoresis analyses, however, both types produced the same bands with molecular weights of 55,000 and 57,000, indicating that they are two different forms composed of common constituents. During the growth phase, the two types of the enzyme were present in culture supernatant in roughly equal amounts, but type II accumulated predominantly in the aggregation phase, suggesting that the ratio of activity of the two forms is under developmental control. Rabbit antiserum prepared against purified type II enzyme cross-reacted with type I as well as membrane-bound enzyme, indicating that the three classes of the enzyme possess some common sequence.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

Cell differentiation in a temperature-sensitive stalkless mutant of Dictyostelium discoideum.

A temperature-sensitive aggregateless and stalkless mutant was isolated from Dictyostelium discoideum NC-4. The mutant cells cannot aggregate at 27 degrees C, but aggregate and form normal fruiting bodies at 21 degrees C. When the temperature was shifted to 27 degrees C after aggregation at 21 degrees C, almost all of the cells in the aggregate differentiated into spores. Neither stalk cells nor stalk tubes formed at 27 degrees C. Inhibition of stalk formation was not lifted by addition of cyclic AMP. Nevertheless, the proportion of prespore to total cells within the mutant slugs was normal, at both 21 degrees C and 27 degrees C. At 27 degrees C, a slug was transformed into a spherical cell mass at the end of migration, within which pre-existing prespore cells differentiated into spores. The remaining prestalk cells were then converted to prespore cells which later became spores. As the cell-type conversion continued, formation of a spore mass resulted. The development of the mutant is thus consistent with the idea that the presumptive cell differentiation is directly related to the terminal cell differentiation. During migration at 27 degrees C, the number of prestalk cells decreased in the anterior part of the slug but instead increased at the foot or the rear part, whereas the prestalk-prespore pattern remained normal at 21 degrees C. The fact that a normal proportion of prespore cells was maintained in spite of their deranged distribution at 27 degrees C indicates that the regulation of proportion is independent of the formation of pattern.

Cyclic AMP↗
PubMed1983

Proportion regulation without pattern formation in Dictyostelium discoideum.

When shaken in a glucose-albumin-cAMP medium, dissociated aggregative cells formed small clumps, in which both prespore and prestalk cells differentiated in essentially the same proportions as in a slug. Immunocytochemical staining of sections of such clumps revealed that the two types of cells showed no particular pattern of distribution, unlike the two-zoned prestalk-prespore pattern as observed in the slug. Cells dissociated at stages later than the onset of aggregation always produced a constant proportion of prespore cells, irrespective of the initial proportion when transferred to the culture. Furthermore, prestalk cells fractionated from slugs and transferred to the culture restored almost the normal prespore protortion through conversion of the cell types, whereas proportion of unfractionated slug cells remained unchanged. We conclude from these findings that the normal prestalk-prespore pattern is not required for proportion to be regulated.

Cell Aggregation↗
PubMed1982

Effects of cyclic AMP on contact formation and differentiation in Dictyostelium discoideum.

It has been shown previously that Dictyostelium discoideum NC4 cells dissociated at the early aggregation stage form cell clumps and differentiate into prespore cells in a shaking culture containing glucose, albumin, EDTA and cyclic AMP. In this culture system, we found that the cells neither differentiate nor form cell clumps in the absence of cyclic AMP. Wheat-germ agglutinin (WGA) completely inhibited the cyclic AMP-induced formation of cell contact and the inhibition was nullified by the addition of N-acetyl-D-glucosamine. When the cells were prevented from forming contact by either rapid shaking or the addition of WGA, they were unable to differentiate even in the presence of cyclic AMP, indicating that contact formation is a prerequisite for prespore differentiation. Cells dissociated from migrating slugs formed cell clumps in shaking culture, with or without cyclic AMP, and the cell contact was sensitive to WGA. In the absence of cyclic AMP, prespore cells lost their differentiated state, even though the cells were in contact. This indicates that cyclic AMP has a second effect, that of pomoting differentiation, in addition to the effect of inducing contact formation. Both effects were required for prespore differentiation of strain NC4 cells.

Cell Adhesion↗