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Biomedical subjects

Y Fukui

Publications and source records attributed to Y Fukui.

At least 325 records · Page 18Linked to original sources
PubMed1992

Effect of copper(II) chloride on suppression of racemization in peptide synthesis by the carbodiimide method.

Copper(II) chloride was found to be an extremely efficient racemization-suppressing additive in the DCC method as compared with the hitherto known ones, by employing the model coupling Z-Gly-L-Val-OH + H-L-Val-OMe in DMF. Although some other copper salts also had a profound effect, copper(II) chloride was the best from the viewpoint of both racemization suppression and coupling efficiency. The effectiveness of copper(II) chloride was further confirmed by employing the EDC-mediated couplings of Z-Gly-containing dipeptides with amino acid esters or dipeptide esters, and those of Z-L-Ala (or L-Val)-L-Val-OH with amino acid esters or dipeptide esters. In almost all the cases studied, no detectable amount (less than 0.1%) of epimer was observed by the HPLC analysis in the presence of copper(II) chloride. This was also the case even with an extremely stringent coupling system Z-L-Pro-L-Val-OH + H-L-Pro-OMe. With reference to the mechanism of racemization suppression, it was found that copper(II) chloride has a strong ability to suppress the racemization of the 5(4H)-oxazolone, which may be formed from an activated carboxyl component during the coupling.

Amino Acid Sequence↗
PubMed1992

Simultaneous use of 1-hydroxybenzotriazole and copper(II) chloride as additives for racemization-free and efficient peptide synthesis by the carbodiimide method.

In the carbodiimide mediated coupling of Z-Gly-L-Val-OH with H-L-Val-OMe in DMF, the simultaneous use of HOBt and copper(II) chloride as additives was found to give the desired peptide in a high yield without racemization. In the presence of HOBt, reducing the amount of copper(II) chloride produced a higher yield. Besides improving the coupling efficiency as compared with the case using copper(II) chloride alone as an additive, the present procedure offered another advantage for racemization suppression. Thus, even for the couplings where a low level of racemization was observed in the presence of copper(II) chloride, the simultaneous addition of HOBt and copper(II) chloride resulted in the elimination of racemization. The effectiveness of this new procedure using the two carbodiimide additives in the synthesis of biologically active peptides was assessed by the preparation of a protected Leu-enkephalin. In the 4 + 1 segment condensation using HOBt and copper(II) chloride simultaneously as additives, no racemization was detected and the yield was high enough. The elimination of racemization and improvement of coupling efficiency produced by the present procedure can be attributable to a reduced tendency for the activated forms of the carboxyl component to form a 5(4H)-oxazolone by the action of HOBt, and to the prevention of racemization by copper(II) chloride of the small amount of the oxazolone formed which is not eliminated by the action of HOBt alone.

Amino Acid Sequence↗
PubMed1992

Quantitative immunocytochemical analysis of the induction of cytochrome P450IIB in rat hepatocytes.

We examined whether induction of the phenobarbital (PB)-inducible form of cytochrome P450 (P450IIB) in rat hepatocytes could be analyzed quantitatively by immunogold electron microscopy. Rats received intraperitoneal injections of PB every 24 hr and livers at the various stages of PB induction were fixed by perfusion with a mixture of paraformaldehyde (4%) and glutaraldehyde (0.1%) and embedded in LR White. Ultra-thin sections were cut and labeled by the protein A-gold procedure using affinity-purified anti-P450IIB antibody which was previously immunoabsorbed with liver microsomes from a control rat (not treated with PB). We counted the number of gold particles per micron of the rough ER membranes (particle density). Before PB treatment, the particle density of the rough ER in rat hepatocytes was practically zero and increased markedly at 48 and 72 hr after PB treatment. The rough microsomes were prepared from these PB-treated rat livers. The amount of P450IIB was estimated by immunoblot analysis and the number of gold particles bound to the rough microsomal membrane was determined by the same post-embedding immunogold procedure. The particle density of the rough microsomes increased in parallel with the increase in the amount of P450IIB, indicating good correlation of the two variables. Thus, the induction of cytochrome P450IIB can be quantitatively and reliably investigated by immunogold electron microscopy.

Acrylic Resins↗
PubMed1992

Effects of hyperthermia induced by microwave irradiation on brain development in mice.

Pregnant mice were exposed to 2.45 GHz of microwave radiation for 15 or 20 min on day 13 of gestation. The highest maternal core temperature during the exposure did not exceed 42.5 degrees C. Pregnant females also were immersed in hot water at 42 degrees C for 15 min to compare thermal effects on brain development. Animals were killed 9 hours after treatment, and the pyknotic cells in the ventricular zone of telencephalon were counted. The respective incidences of these cells in the groups exposed to microwaves for 15 and 20 min were 1.83% and 3.06%. Microwave radiation for 20 min had an effect that was comparable to that of immersion in 42 degrees C hot water for 15 min. In addition, some animals were examined on day 18 of gestation, and some of their offspring were examined at 6 weeks of age in an examination of long-term effects. Brain weight for the group exposed to microwaves for 20 min was significantly lower than for the control group, and the numerical density of the neurons in the cerebrum was higher. We concluded that microwave radiation at the dose tested mainly has a thermal effect.

Animals↗
PubMed1992

[Trace analysis for drugs and poisons in human tissues].

Despite continuous developments of analytical techniques in terms of sensitivity and accuracy, uncountable increase in number of chemical substances are brought into the field of forensic sciences to be analyzed. Based on the idea that progress in analytical technique to cope with the change of situation is always required, a research team including 10 members was organized to set up the most advanced methods at present to analyze the important drugs and poisons in biological materials for forensic purposes. Stimulant drugs such as methamphetamine and amphetamine were studied on the improvement of extraction procedure prior to mass spectrometric analysis. A conventional solvent extraction method was replaced by an extraction technique using Extrelut column. The technical procedure was simplified and the accuracy of measurement was improved. The changes in CO-Hb concentration in the whole blood in storage was examined with regard to the lapse of time and temperature, where a differential spectrophotometry was used. Useful information could be obtained from practical aspects. Analytical conditions of gas chromatography were revised on volatiles including alcohols, especially as to column conditions. The use of capillary column was recommended for sensitivity and peak separation. The optimum conditions for detecting barbiturates in the blood were examined. The combination of Sep-pak C18 cartridge with a capillary column for gas chromatography using nitrogen phosphorus detection was found preferable. Mass spectrometry of various kinds of local anesthetics was studied. Quantitative analysis of the drugs was examined on gas chromatography with a surface ionization detector. Three types of insecticides including organophosphorus, chlorinated and fluorine compounds were analyzed by gas chromatography/mass spectrometry in order to establish a sensitive and selective method. The detection limits, calibration and reproducibility were examined. Herbicide, paraquat, was examined on the sensitivity, recovery, required time and costs in connection with methods of pretreatment and analytical procedure. A secondary spectrophotometry was found useful practically. Antimony in biological tissues was analyzed, using a flameless atomic absorption spectrometer with carbon tube atomizer. The time for analysis was reduced, and sensitivity was improved. Immunoassay method was examined from general aspects on drugs and hormones. Using antibodies specific to haptens, the dynamics of such antigens as drugs and hormones in the body tissues were observed. Interfering substances at the time of toxicological analysis were checked in order to obtain reliable information. Exact identification was found possible by using gas chromatography/mass spectrometry. As described above, the research was made from the practical aspects of forensic toxicology, and meaningful results could be obtained from each study.

Animals↗
PubMed1992

Can death at a low COHb concentration frequently observed in fire victims be explained by hypoxic hypoxia?

Fire deaths at low COHb (carboxyhemoglobin) concentrations are frequently observed, but it is difficult to determine the causative factors. Participation of hypoxic hypoxia was examined using rats and rabbits exposed to various low-O2 and CO gas mixtures. The ranges of O2 and CO concentration were 3.0-22.2% and 0.3-2.9%, respectively. The concentration of CO2 was fixed at about 5%. Rats were individually exposed to the test gas in a plastic chamber. Rabbits inhaled the test gas through a tracheal cannula. The survival time of rats ranged from 3.9-7.7 min, and that of rabbits was 8.0-22.5 min. Rats exposed to the most hypoxic gas mixture (O2 3%-CO 0.3%) died with COHb values below 40%. Rabbits also died with a low COHb concentration under this condition, but the COHb concentration was not below 50%. Rabbits were considered to be more resistant to hypoxic hypoxia than rats. From the literature on the relationship between the grade of burns and the concentration of COHb, as well as the findings obtained in the present experiment, hypoxic hypoxia did not appear to be a main factor causing death at low COHb concentrations. In the rabbit the COHb concentration increased exponentially and reached plateau levels within 10 min in many groups. The time required to reach a plateau COHb level was shorter when the concentration of CO was high and that of O2 was low.

Animals↗
PubMed1992

[Functional expression of xenogenic mixed isotype molecule, DR alpha E beta, in transgenic mice with HLA-DRA gene on X chromosome].

A line of transgenic mice was established, in which HLA-DRA gene was integrated into the X chromosome and was stably transmitted to their progenies. The expression of DRA gene and immunological phenomena in the transgenic mice was investigated. 1) The DR alpha chain was associated with murine E beta b chain and xenogenic mixed isotype heterodimer DR alpha E beta b was expressed on immunocompetent cells, such as B cells, macrophages, dendritic cells, and thymic epithelial cells, despite that transgenic DRA gene contained only 268-bp of the 5'-flanking region. 2) The DR alpha E beta b molecules as well as E alpha E beta b functioned as major histocompatibility complex class II molecules to select T cell repertoire, to stimulate mixed lymphocyte reaction, and to induce proliferation of T cells specific to moth cytochrome c peptide (MCC 81-103). The 25% of amino acid substitutions between the DR alpha and the E alpha did not affect presentation of MCC 81-103 to T cell receptor (TCR) recognizing the peptide in the context of E alpha E beta b or E alpha E beta k. 3) In female mice hemizygous for HLA-DRA, the proportion of cells expressing the DR alpha E beta b molecules varied from one to another due to Lyonization. Clonal deletion of self-reactive T cells bearing TCR V beta 5 or V beta 11 was incomplete particularly when less than 20% of spleen cells were positive for DR alpha E beta b molecules. However, self-tolerance was acquired in these mice.

Animals↗
PubMed1992

Establishment of an experimental model of autoimmune epididymo-orchitis induced by the transfer of a T-cell line in mice.

A murine T-cell line derived from BALB/c mice (designated B.T.1) was established which was capable of adoptively transferring experimental autoimmune orchitis (EAO) in normal recipients. The protocol consisted of preparing lymphocytes obtained from the mice that were immunized with syngenetic testicular germ cells (TGC) and the subsequent repeated selection of the lymphocytes in vitro by stimulation with murine testicular antigens (mTA). Phenotypic analysis revealed that B.T.1 cells were CD4+ T-cells. Intra-peritoneal inoculation of as few as 1 x 10(5) B.T.1 cells, that were stimulated in vitro with mTA before the inoculation, was capable of transferring EAO to naive recipients. In the latter, both delayed type hypersensitivity (DTH) and humoral responses to TGC were augmented. The transferred lesion was characterized by infiltration of inflammatory cells into the epididymis and rete testis and widespread aspermatogenesis in the testis. The transfer of EAO was unsuccessful when the recipients received B.T.1 cells that were maintained in culture medium without stimulation with mTA. In these recipients, anti-TC DTH was not detected, although the specific humoral response was observed. In-vitro characterization of the biological activity of B.T.1 cells revealed that the line had no cytolytic activity against TGC but the culture supernatant had macrophage migration inhibitory activity involved in the DTH response. Therefore, the DTH responsiveness transferred by B.T.1 cells was found to correlate with their orchitis-inducing capacity.

Animals↗
PubMed1992

[Intraocular barrier permeability in spontaneously diabetic Chinese hamster].

Fluorophotometry was performed with normal and spontaneously diabetic Chinese hamsters (CHAD) in order to investigate differences in blood-ocular barrier permeability and lens autofluorescence. Blood-aqueous barrier permeability was evaluated by the fluorescence value in the anterior chamber which was corrected using both autofluorescence value and the concentration of fluorescein in the plasma. The results showed that the diabetic group had significantly higher values than the normal group (p less than 0.01). Blood-retinal barrier permeability was evaluated in the vitreous by the same method. There was no significant difference between the two groups. Lens autofluorescence values were also significantly higher for the diabetic group compared with the normal group (p less than 0.001). In these spontaneously diabetic Chinese hamsters, the permeability function of the blood-retinal barrier seemed to be maintained its normal level, while both the blood-aqueous barrier and lens were damaged by deleterious effects of diabetes.

Animals↗
PubMed1992

[Relationship between juxtapapillary duodenal diverticula and biliopancreatic disease--evaluation by endoscopic biliary manometry].

Endoscopic biliary manometry was performed to evaluate the motor activity of the sphincter of Oddi (SO) in 28 patients, 13 with juxtapapillary duodenal diverticula (8 with biliopancreatic disease) and 15 without diverticula (10 with biliopancreatic disease). So pressure and the rate of irregular wave pattern of phasic contraction in patients with diverticula were significantly higher than those in patients without diverticula. Especially all the patients with both diverticula and biliary stones had motor disorders of the SO. The patients with diverticula were also divided into three groups by endoscopic findings for the location of diverticular; The papilla of Vater was located close to diverticula (within about 4 cm) in group A, on the edge of diverticula in group B, in the diverticula in group C. Diverticula could have more direct effect on the motor activity of the SO in group C. Those results suggest juxtapapillary diverticula have close relationship with the motor activity of the SO and biliopancreatic disease, especially in cases which the papilla of Vater located in the diverticula. We conclude that the motor disorders of the SO might be responsible for biliopancreatic disease in patients with juxtapapillary diverticula.

Ampulla of Vater↗
PubMed1992

Teratogenic effects of methamphetamine in mice.

Eight-day pregnant Jcl:ICR mice were administered methamphetamine hydrochloride i.p. at doses of 11, 13, 14, 15, 17, 19 and 21 mg/kg. The number of animals that died after the treatment increased dose-dependently. The highest maternal mortality rate (50%) was observed in the 21 mg/kg group. On day 18 of gestation, the animals were killed and fetuses were examined for external and skeletal malformations. The mortality and malformation rates of fetuses increased with the increase in dose, but both rates reached their highest levels at a dose of 19 mg/kg. Exencephaly, open eyelids, cleft palate and rib anomaly were frequently observed malformations. The single teratogenic dose was estimated to be 19 mg/kg for both external and skeletal malformations. This amount was about ten times the daily intake of many Japanese abusers. The risk of malformed infants being born to female abusers was considered to be high. More crowded conditions have been reported to increase the fetal malformation rate. The higher malformation rate in the 19 mg/kg group than in the 21 mg/kg group was considered to be due to fewer surviving mice in the 21 mg/kg group, because of a higher mortality rate.

Abnormalities, Drug-Induced↗
PubMed1991

Cell division in Dictyostelium with special emphasis on actomyosin organization in cytokinesis.

This study focuses on the dynamic reorganization of actin and myosin ("conventional" myosin, or myosin-II) during cytokinesis in D. discoideum. This is the first study identifying the birefringence of the spindle microtubules as well as three sets of microfilamentous structure in Dictyostelium. The change of organization in these fibrillar structures was followed in real-time with video microscopy, using a Universal Polarizing Microscope equipped with polarized-light (POL) and differential interference contrast (DIC) optics combined with digital image processing. High-frequency mitotic cells were obtained by semi-synchronous culture, and high-resolution observations were made by utilizing the agar-overlay method (Yumura et al.: Journal of Cell Biology 99:894-899, 1984). The molecular identity of the birefringent structures was determined by fluorescence microscopy. Through-focus observations were performed with an axial resolution of 0.3 micron depth of field. The actomyosin fibrils show a dramatic reorganization throughout mitosis. The fibrils at the leading lamellipodia disappear, and there is a striking assembly of the cortical actomyosin in pro-metaphase, which is accompanied by a decrease in cell volume. The cortical actomyosin gradually increases through anaphase. After late anaphase, very active polar lamellipodia, with an average life of less than 1 minute, are formed. We confirmed that the polar lamellipodia include actin, but not myosin-II. At the cleavage furrow, the microfilaments form two distinctive structures: circular contractile ring at the equator, and a cortical filament array parallel to the polar axis. Myosin is localized in the contractile ring, but not associated with the axial array of F-actin. Actomyosin in the contractile ring gradually transforms into cortical network at the posterior region of daughter cells. The constriction of the furrow is accompanied by a drastic efflux of water as evidenced by highly active contractile vacuole formation and turbulent motion of minute vesicles connected to the furrow. This study demonstrates the presence of a new microfilament structure, as well as the dynamic property of the contractile ring, and sheds new light on the contractile mechanisms underlying cytokinesis.

Actomyosin↗
PubMed1991

Cytochrome P-45011 beta in rat brain.

The presence of cytochrome P-45011 beta in rat brain was studied by immunohistochemistry using polyclonal rabbit antibodies raised against purified bovine adrenocortical P-45011 beta, which is involved in the steroid 11 beta-hydroxylation and glucocorticoid formation. The results showed that cytochrome P-45011 beta immunoreactivity is selectively localized to the tracts of myelinated fibers throughout the brain. The specificity of immunohistochemical stainings with P-45011 beta antibodies was established by control tests including nonimmune rabbit immunoglobulin Gs and P-45011 beta antibodies absorbed with purified antigen. Western immunoblots of homogenates from different brain areas with P-45011 beta antibodies, together with biochemical enzymatic assays for cytochrome P-45011 beta monooxygenase activity in these homogenates, confirmed the selective localization of this enzyme observed with immunohistochemistry. Cytochrome P-45011 beta and 11 beta-hydroxylase activity were detected in a homogenate from the cortical white matter (brain area rich in myelinated fibers) as in that from the rat adrenal, but were not detectable in a homogenate from the cerebral cortex (brain area poor in myelinated fibers). Furthermore, quantitation of the P-45011 beta bands on the immunoblots by the areal density revealed that the cortical white matter contains approximately 1.4 pmol of cytochrome P-45011 beta/mg of tissue protein, the value of which was about one sixth of the corresponding value estimated in the rat adrenal. This relatively high content of cytochrome P-45011 beta was also reflected in a relatively high level of 11 beta-hydroxylase activity measured in a homogenate of this brain area by biochemical enzymatic assays using [4-14C]-11-deoxycorticosterone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex↗
PubMed1991

Developmental disturbance of rat cerebral cortex following prenatal low-dose gamma-irradiation: a quantitative study.

Pregnant rats were exposed to a single whole-body gamma-irradiation on Day 15 of gestation at a dose of 0.27, 0.48, 1.00, or 1.46 Gy. They were allowed to give birth and the offspring were killed at 6 or 12 weeks of age for microscopic and electron microscopic examinations of the cerebrum. Their body weight, brain weight, cortical thickness, and numerical densities of whole cells and synapses in somatosensory cortex were examined. Growth of the dendritic arborization of layer V pyramidal cells was also examined quantitatively with Golgi-Cox specimens. A significant dose-related reduction in brain weight was found in all irradiated groups. Neither gross malformation nor abnormality of cortical architecture was observed in the groups exposed to 0.27 Gy. A significant change was found in thickness of cortex in the groups exposed to 0.48 Gy or more. Cell packing density increased significantly in the group exposed to 1.00 Gy. Significant reduction in the number of intersections of dendrites with the zonal boundaries were found in the groups exposed to 0.27 Gy or more. There was no difference in the numerical density of synapses in layer I between the control and irradiated groups. These results suggested that doses as low as 0.27 Gy could cause a morphologically discernible change in the mammalian cerebrum.

Animals↗