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Biomedical subjects

K Horie

Publications and source records attributed to K Horie.

At least 181 records · Page 10Linked to original sources
PubMed1986

Impaired steroidogenic function of corpora lutea from hyperprolactinemic baboons induced by sulpiride.

It has been noticed that hyperprolactinemia can cause luteal insufficiency as well as anovulation in women. In order to explore the mechanism underlying this disorder, hyperprolactinemia was induced in baboons (Papio cynocephalus) by daily administration of sulpiride during follicular and early luteal phases. In hyperprolactinemic baboons, the plasma progesterone level was suppressed without notable changes in plasma estradiol, LH and FSH levels. When corpora lutea from these baboons were examined in vitro to investigate their ability to convert 14C-pregnenolone into various steroids, there was progressive inhibition of steroid metabolism related to the plasma levels of prolactin. These findings strongly suggest, although do not actually prove, that an elevated level of prolactin could directly impair luteal function by adversely affecting 3 beta-hydroxysteroid dehydrogenase activity.

Animals↗
PubMed1985

Mathematical models of cell variation seen in a heterogeneous malignant cell population.

We established mathematical models for the cell variation seen in a heterogeneous malignant cell population, with the supposition that it occurs as the result of the competition between two types of cells, (A) and (B), leading to a change of stem cells. Models I and II: In the case of differences in the ability of (A) and (B) cells to adapt themselves to an environment, the proportion of cells which are less adaptable to the environment decreases exponentially and eventually disappears. Model III supposes that under certain environmental conditions, the two types of cells exist simultaneously in fixed proportions, and transformations of (B) cell to (A) cell and of (A) cell to (B) cell occur at a certain rate but are independent of each other. This process is considered to follow the Markov's chain theory. Based on this supposition, we established Model III and introduced the concept of "coefficient of cell variation". We found that Model III fits the process of cell variation seen in m cell line and we calculated the coefficients of cell variation seen in this cell line in different environments. The possible mechanism of the cell variation of this cell line is discussed.

Animals↗
PubMed1985

The time interval effect on two consecutive LHRH-TRH tests on adult female baboons.

To Clarify the relationship between the time interval and pituitary Luteinizing hormone (LH), Follicular stimulation hormone (FSH) and prolactin (PRL) secretion function under LHRH-TRH stimulation, 4 mature female baboons were used. Two consecutive LHRH (100 micrograms)-TRH (250 micrograms) stimulations with a 60 min interval between them was carried out in the early follicular phase, late follicular phase and mid luteal phase in the same baboon in the first menstrual cycle, then carried out with a 120 min interval between tests in the third menstrual cycle. The LH, FSH and PRL were measured by specific radioimmunoassay. The PRL maximum response to the first bolus of TRH was higher than maximum response to the second bolus of TRH. The PRL maximum response to the second TRH at a 120 min interval was higher than the maximum response to the second TRH at a 60 min interval. It seems that the TRH had the dominant effect on PRL releasing but not on PRL Priming. The maximum LH response to the second bolus of LHRH was higher than the maximum response to the first bolus of LHRH. The LH maximum response to the second bolus of LHRH at a 60 min interval was greater than the maximum response at a 120 min interval in the follicular phase but it was the reverse in the luteal phase. The FSH response to the second LHRH was different from the LH response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

[A basic study on the anti-tumor activity of peripheral lymphocytes of tumor-bearing rats by in vitro culture].

In order to establish passive cancer immunotherapy by in vitro culture of lymphocytes, several methods were devised to induce and augment anti-tumor activity of peripheral blood lymphocytes (PBL) in the presence of interleukin-2 (IL-2). In vitro experiment: Weak anti-tumor activity appeared on culture of PBL in the presence of IL-2. On addition of MMC treated tumor antigen, the anti-tumor activity was augmented. Anti-tumor activity further increased on addition of peritoneal exudate macrophages or peripheral whole white blood cells containing monocytes to (2) as accessory cells. Effect similar to (3) was obtained in MLTC of peripheral whole white blood cells. [II] In Winn neutralization test, the strongest tumor-neutralizing activity was seen in the group of cultured lymphocytes with antigen and in the group of cultured leukocytes with antigen. This result agreed excellently with the results of the in vitro experiments [I]. [III] In the therapeutic experiment: Significantly better effect was noted in the treated group by cultured leukocytes with antigen than in the treated group by non-cultured lymphocytes. The treatment with 10(7) lymphocytes produced definitely prolonged survival of tumor-bearing rats compared to the treatment of 10(6) or less number lymphocytes.

Animals↗
PubMed1984

A highly sensitive photometric method for proton release or uptake: difference protometry.

A highly sensitive quantitative method was developed to detect protons released or taken up upon ligand binding. A small change in pH due to proton release or uptake was detected by measuring the difference in the absorbance of a pH indicator upon ligand addition. Owing to the difference detection of protons, the uncertainty of pH due to CO2 dissolution and unknown buffering capacities of sample solutes could be compensated with easy manipulations. Precise calibration of the absolute amount of protons could also be made very easily. The amount of protons measurable by the method is as small as 0.5 nmol that is 10 to 30 times more sensitive than the pH-stat method. We measured the Mg2+ ion-induced proton releases of ADP to confirm the accuracy and reliability of the method and of Escherichia coli ribosomes to show the improvement in sensitivity. The method is useful for protometric studies of biomolecules that are difficult to obtain in large amount.

Acid-Base Equilibrium↗
PubMed1984

Mg2+-induced proton release from Escherichia coli ribosome and ribosomal RNA.

Escherichia coli ribosome released protons upon addition of Mg2+. The Mg2+-induced proton release was studied by means of the pH-stat technique. The number of protons released from a 70 S ribosome in the Mg2+ concentration range 1-20 mM was about 30 at pH 7 and 7.6, and increased to about 40 at pH 6.5. The rRNA mixture extracted from 70 S ribosome showed proton release of amount and of pH dependence similar to those of the 70 S ribosome but the ribosomal protein mixture released few. This indicates that rRNA is the main source of the protons released from ribosome. The pH titration of rRNA showed that the pKa values of nucleotide bases were downward shifted upon Mg2+ binding. This pKa shift can account for the proton release. The Scatchard plots of proton release from rRNA and ribosome were concave upward, showing that the Mg2+-binding sites leading to proton release were either heterogeneous or had a negative cooperativity. A model assuming heterogeneous Mg2+-binding sites is shown to be unable to explain the proton release. Electrostatic field effect models are proposed in which Mg2+ modulates the electrostatic field of phosphate groups and the potential change induces a shift of the pKa values of bases that leads to the proton release. These models can explain the main features of the proton release.

Binding Sites↗
PubMed1984

A comparison of the tensile bond strengths of composite resins to longitudinal and transverse sections of enamel prisms in human teeth.

The tensile bond strengths of composite resins to transverse and longitudinal sections of enamel prisms etched with phosphoric acid were examined. The tensile bond strengths were 18-19 MPa to the transverse and 10-11 MPa to the longitudinal sections and thus were influenced by the nature of the enamel crystal planes. These facts suggest that composite resin restorations will have a longer life span if the enamel walls are given marginal forms to produce transverse rather than longitudinal sections of enamel prisms.

Acid Etching, Dental↗