High-resolution measurement of massive-dielectron production in 800-GeV proton-beryllium collisions.
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Journal Article↗
Biomedical subjects
Y Sakai
Publications and source records attributed to Y Sakai.
Experimental evidence for the non-Abelian nature of QCD from a study of multijet events produced in e+e- annihilation.
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Journal Article↗
Calcium mobilization and phosphatidylinositol turnover in vas deferens smooth muscle of diabetic rats.
The study concerned Ca2+ channels that are receptor-operated by norepinephrine (NE) and mediate hyper-reactivity of vas deferens smooth muscle from rats with streptozotocin (STZ)-induced diabetes, and the mediatory responses of these channels, such as tension development, Ca2+ uptake and phosphatidylinositol (PI) turnover. The contractile responses induced by adrenoceptor agonists were significantly greater in diabetic rat vas deferens than in the controls. A greater Ca2+ uptake was induced by 10(-5) M NE in strips from diabetic rats than in the controls. The uptake of Ca2+ was completely inhibited by 10(-6) M prazosin but not by 10(-5) M verapamil. Enhancement of Ca2+ release by 10(-5) M NE was faster and greater in diabetic muscles than in the controls. The accumulation of [3H]inositol phosphates was increased 4-fold in the controls and 7-fold in diabetic muscles by 10(-5) M NE. This increase was completely inhibited by 10(-6) M prazosin but not by 10(-6) M yohimbine. The data suggest that vas deferens smooth muscle hyper-reactivity in diabetic rats is due to increased PI turnover mediated by alpha 1-adrenoceptors, to the release of intracellular bound Ca2+ and to an increase of Ca2+ uptake through receptor-operated Ca2+ channels.
Animals↗
A respiratory-driven and an artificially driven ATP synthesis in mutants of Vibrio parahaemolyticus lacking H+-translocating ATPase.
Mutants of Vibrio parahaemolyticus lacking the H+-translocating ATPase were isolated to evaluate both the role of this enzyme and the possibility of the involvement of other cation-translocating ATPase in the energy transduction in this organism. Dicyclohexylcarbodiimide-sensitive ATPase activity which represents the H+-translocating ATPase was not detected either in the membrane vesicles or in the cytosol of the mutants. Three major subunits, alpha, beta and gamma, of the H+-translocating ATPase were missing in the membranes of the mutants. Although ATP was synthesized in wild type cells when an artificial H+ gradient was imposed, little ATP was synthesized in the mutants. However, we observed a large ATP synthesis driven by the respiration not only in the wild type but also in the mutants. The respiratory-driven ATP synthesis in wild type was inhibited by an H+ conductor, carbonylcyanide m-chlorophenylhydrazone, by about 50%. On the other hand, the ATP synthesis in the mutants was not affected by the H+ conductor. Since this organism possesses a respiratory Na+ pump, Na+-coupled ATP synthesis might take place. In fact, we observed some ATP synthesis driven by an artificially imposed Na+ gradient both in the wild type and the mutant.
Adenosine Triphosphate↗
Release of endogenous N-acetylaspartylglutamate (NAAG) and uptake of [3H]NAAG in guinea pig cerebellar slices.
For the purpose of obtaining chemical information about the physiological role of N-acetylaspartylglutamate (NAAG), the release of endogenous NAAG from and the uptake of [3H]NAAG by Guinea pig cerebellar slices were investigated in comparison with L-aspartate (Asp) and L-glutamate (Glu). Although endogenous NAAG was found to be released spontaneously from the slices as is endogenous Asp and Glu, high-K+-induced facilitation of release occurred only for endogenous Asp and Glu in a Ca2+-dependent manner, but not for NAAG. It was confirmed that [3H]NAAG itself was taken up in a Na+-dependent manner by the slices by two low-affinity processes with small Vmax values, and labeled Glu and glutamine were detected as the metabolites of [3H]NAAG in the slices. The [3H]NAAG uptake was slower than that of labeled Glu and was significantly depressed by NAAG, Asp, Glu and D-aspartate, but not affected by gamma-aminobutyrate, suggesting that NAAG may share a common uptake carrier with excitatory amino acids. These results suggest that endogenous NAAG may act extracellularly, but the amount of endogenous NAAG released from nerve terminals by presynaptic depolarization may be very small if any, and also that spontaneously liberated NAAG can be inactivated by low-affinity uptake systems, at least, in the Guinea pig cerebellum.
Animals↗
Low-concentration N-acetylaspartylglutamate suppresses the climbing fiber response of Purkinje cells in guinea pig cerebellar slices and the responses to excitatory amino acids of Xenopus laevis oocytes injected with cerebellar mRNA.
Whether N-acetylaspartylglutamate (NAAG) at micromolar concentrations shows a modulatory action on the synaptic transmission mediated by excitatory amino acids was investigated using Guinea pig cerebellar slices and the Xenopus laevis oocytes injected with mRNA from Guinea pig cerebellum. The climbing fiber response consisted of an excitatory postsynaptic potential (EPSP) and a plateau potential intracellularly recorded from Purkinje cell dendrite was depressed by 30 microM NAAG; the EPSP was decreased by about 21% in amplitude and the plateau potential was depressed by about 42% in duration. The depolarization induced by L-aspartate, L-glutamate, N-methyl-D-aspartate and quisqualate in mRNA-injected Xenopus oocytes were non-selectively antagonized by 0.5 microM-5 microM NAAG, the mean % blockade by 5 microM NAAG being about 38%. Higher concentrations (greater than 100 microM) of NAAG alone by 33% on average by 10 microM NAAG. These results suggest the possibility that micromolar concentrations of NAAG may attenuate the synaptic transmission mediated by glutamate receptors not only by blocking postsynaptic receptors but also by facilitating the high-affinity re-uptake of transmitter amino acids.
Action Potentials↗
Alternative splicing mechanism in a cytochrome P-450 (P-450PB-1) gene generates the two mRNAs coding for proteins of different functions.
Two mRNAs for P-450PB-1 and P-450PB-1(ps) are about 2 kilobase pairs long and have identical sequences with each other except for one short region of high variability (Kimura, H., Yoshioka, H., Sogawa, K., Sakai, Y., and Fujii-Kuriyama, Y. (1988) J. Biol. Chem. 263, 701-707). To clarify the origin of the short replacement block between the two mRNAs, we isolated several genomic clones containing relevant gene sequences. Sequence analysis of these genomic clones revealed that the two short segments specific for the two mRNAs are tandemly arranged in a genomic sequence and form exonic sequences equipped with AG and GT sequences on their 5' and 3' ends, respectively, and the putative consensus sequences for the lariat formation. The two short sequences lie between the two exonic sequences coding for the common part of the two mRNAs. Taken together with the structure of the related P-450(M-1) gene (Morishima, N., Yoshioka, H., Higashi, Y., Sogawa, K., and Fujii-Kuriyama, Y. (1987) Biochemistry 26, 8279-8285), all these results clearly demonstrate that the two mRNAs are generated from a single gene by alternative splicing at the eighth exons. The synthesis of the two mRNAs is regulated temporally in livers of male and female rats and brains of the female animals. One of the two mRNAs codes for a monooxygenase of P-450PB-1, and the other (P-450PB-1(ps) mRNA) lacks the sequence coding for the heme-binding site conserved among all species of P-450 molecules, and, therefore, it cannot function as a monooxygenase. The immunoblot analysis using an antibody specific for the 15-mer peptide uniquely encoded by P-450PB-1(ps) mRNA shows that the P-450PB-1(ps) peptide is synthesized at least in rat livers of both sexes in temporally regulated manners and is bound to the microsomal membranes. The function of this peptide remains to be seen.
Aging↗
[Thin-section computed tomography of intrapulmonary metastases after surgical resection of lung cancer].
To evaluate the morphology of small peripheral intrapulmonary metastases of lung cancers, we studied thin-section computed tomography (CT) images of 12 lesions in 5 cases (1 squamous cell carcinoma, and 4 papillary adenocarcinomas). All lesions were resected, and histopathological diagnosis of them was performed in comparison with primary lesions to differentiate multiple primary lung cancers from intrapulmonary metastases. Thin-section CT images showed mildly lobulated nodules in connection with supplying pulmonary vessels, however, indented pleura and vascular convergence were less frequently seen in intrapulmonary metastases in contrast with primary lung cancers. Thin-section CT is helpful for distinguishing multiple primary lung cancers from intrapulmonary metastases in patients with a history of surgical resection for lung cancers.
Adenocarcinoma, Papillary↗
Mechanism for the removal of residual cytoplasm from spermatids during mouse spermiogenesis.
During spermiogenesis, cytoplasmic processes of Sertoli cells invade spermatid cytoplasm to form a canal complex (Sakai et al., 1988). Thin tubules are formed from the canal complex and intertwine with each other to give rise to the "mixed body." In the present study, analysis of the changes undergone by the intertwining thin tubules indicated that they contribute to the removal of cell organelles from spermatid cytoplasm. Intertwining thin tubules were first detected at step 13. By step 15, their number had greatly increased. In the present study, the membranes of the intertwining thin tubules were clearly observed to be continuous with the spermatid plasma membranes. Thus, the mixed body possibly may be formed as a long pit of the spermatid plasma membrane situated close to the invading Sertoli cell process. With the progress of spermiogenesis, the lumens of the intertwining thin tubules gradually became swollen, and the intertwining swollen tubules fused with each other so that the spermatid cytoplasm enclosed by the intertwining swollen tubules isolated into fragments. This fragmented cytoplasm, which contained a large amount of endoplasmic reticulum, became spherical. Small branches of the invading Sertoli cell processes entered into the lumens of the intertwining swollen tubules and occupied their interior to the point that, finally, they completely engulfed the fragmented spermatid cytoplasm. Because the invading Sertoli cell processes were continuous with Sertoli cell bodies surrounding a spermatid at this step, it is possible for the fragmented cytoplasm to be transported into the latter by way of the invading Sertoli cell processes.
Adenosine Triphosphatases↗
Neurulation in the mouse: manner and timing of neural tube closure.
The manner and timing of neural fold fusion in primary neurulation were studied in 1,575 normal ICR mouse embryos by using binocular dissecting, light, and scanning electron microscopy. The initial fusion of apposing neural folds occurred at the level of the intermediate point between the third and fourth somites (i.e., in the caudal myelencephalon) and proceeded both rostrally and caudally. A second fusion occurred at what was originally the rostral end of the neural plate and proceeded rostrodorsally. A third fusion occurred in the caudal diencephalon and proceeded both rostrally and caudally. This was followed by complete closure of the telencephalic neuropore at the midpoint of the telencephalic roof and then complete closure of the metencephalic neuropore at the rostral part of the metencephalic roof. A fourth fusion occurred at what was originally the caudal end of the neural plate and proceeded rostrally. Finally, the caudal neuropore completely closed at the level of the caudal end of the future 33rd somite.
Aging↗
A possible mechanism for increments of calcium and protein kinase C activity in kidney of experimental acute fluorosis.
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Animals↗
Twenty-four-hour changes in pinealocytes, capillary endothelial cells and pericapillary and intercellular spaces in the pineal gland of the mouse. Semiquantitative electron-microscopic observations.
Semiquantitative electron-microscopic observations on the pineal gland of dd-mice were carried out to determine whether 24-h rhythms exist in pinealocytes, pericapillary and intercellular spaces and capillary endothelial cells. Nuclear and cytoplasmic areas of pinealocytes and the area of condensed chromatin in pinealocytes showed inversely related circadian rhythms; the former two increased, whereas the latter decreased, during the light period. The extent of pericapillary and wide intercellular spaces exhibited 24-h changes, with an increase and decrease occurring during the light period and the dark period, respectively. The cross-sectional area of endothelial cells decreased and the number of fenestrae increased during the light period; this was reversed during the dark period. The results suggest that the increase in the nuclear and cytoplasmic areas of pinealocytes, the area of pericapillary and wide intercellular spaces and the number of fenestrae, and the decrease in the area of condensed chromatin and endothelial cells during the light period may be related to an increase in synthetic activity of pinealocytes in the mouse.
Animals↗
Changes in endoplasmic reticulum during spermiogenesis in the mouse.
Changes in the endoplasmic reticulum of mouse spermatids during spermiogenesis were examined by scanning electron microscopy, applying the OsO4-DMSO-OsO4 method, which permits 3-dimensional observation of cell organelles. At the same time, the endoplasmic reticulum was stained selectively by the Ur-Pb-Cu method, and 0.5 micron-thick sections were prepared for observation by transmission electron microscopy. The results demonstrated stereoscopically the mode of disappearance of the endoplasmic reticulum. In spermatids of the early maturation phase, the endoplasmic reticulum was of uniform diameter, branched and anastomosed, forming a complicated three-dimensional network throughout the cytoplasm. A two-dimensional net was also noted to have formed just beneath the plasma membrane and about Sertoli cell processes invaginating the spermatid cytoplasm. As spermiogenesis progressed, the spread-out endoplasmic reticulum gradually aggregated to form a condensed, glomerulus-like structure consisting of a very thin endoplasmic reticulum connected to the surrounding endoplasmic reticulum. This structure corresponds to the so-called "radial body". Thus, the endoplasmic reticulum may aggregate, condense, be transformed into a radial body, and be removed from the cytoplasm. The two-dimensional endoplasmic reticulum-net, just beneath the plasma membrane and surrounding processes of Sertoli cells, disappeared in spaces where the three-dimensional endoplasmic reticulum network was scarce. Both the two-dimensional endoplasmic reticulum-net structure and the three-dimensional endoplasmic reticulum network disappeared at the same time, indicating that they may be closely related.
Animals↗
Serum insulin-like growth factor II in chronic liver disease.
Insulin-like growth factor II is secreted primarily by the liver and is reported to be transcribed in many primary hepatocellular carcinoma (PHC) cell lines. We have studied diagnostic significance of serum IGF-II in chronic liver diseases using specific enzyme immunoassay. Serum IGF-II levels (mean +/- SE) were decreased in chronic hepatitis (538 +/- 51 ng/ml; N = 29), liver cirrhosis (427 +/- 45; 50) and PHC (260 +/- 41; 17) compared to controls (830 +/- 49; 57). Serum IGF-II was not different from controls in any of nonhepatic diseases such as diabetes (1032 +/- 97; 19) pancreatic cancer (1413 +/- 282; 8), chronic pancreatitis (999 +/- 126; 17), peptic ulcer (1186 +/- 43; 11), irritable bowel syndrome (1002 +/- 109; 12), gastrointestinal tract cancer (1250 +/- 216; 21) and chronic renal failure (733 +/- 135; 14). In liver diseases serum IGF-II showed a significant correlation with liver function test (negative with retention of indocyanine green and total bile acids; positive with albumin, thrombo-test, and cholinesterase). These results suggest that serum IGF-II reflects a reduced production of IGF-II in the liver and that it can be an index for the residual capacity of liver function.
Adult↗
Enzyme immunoassay for serum pancreatic lipase in the diagnosis of pancreatic diseases.
To evaluate the diagnostic utility of serum immunoreactive lipase (IRL), serum lipase was determined using an enzyme immunoassay and a turbidimetric method along with total serum amylase in 41 healthy controls, 76 patients with pancreatic disease and 60 with nonpancreatic disease. Serum IRL was elevated in 12 of 13 patients with acute pancreatitis, 12 of 44 with chronic pancreatitis and in 12 of 19 with pancreatic cancer. The IRL was low in 9 of the 44 patients with chronic pancreatitis, which coincided with advanced exocrine pancreatic insufficiency. Overall sensitivities in pancreatic diseases were 59% for serum IRL, 38% for turbidimetric lipase and 51% for amylase, specificities in healthy controls and nonpancreatic diseases were 80% for serum IRL, 86% for turbidimetric lipase and 88% for serum amylase. Serum IRL determination is useful for diagnosis in pancreatic diseases when compared with the conventional determination of serum lipase.
Adult↗
Polyamine stimulation of ribosomal synthesis and activity in a polyamine-dependent mutant of Escherichia coli.
A polyamine-dependent mutant of Escherichia coli KK101 was isolated by treatment of E. coli MA261 with N-methyl-N'-nitro-N-nitrosoguanidine. In the absence of putrescine, doubling time of the mutant was 496 min. The mutation was accompanied by a change in the nature of the 30 S ribosomal subunits. Addition of putrescine to the mutant stimulated the synthesis of proteins and subsequently, this led to stimulation of RNA and DNA synthesis. Under these conditions, we determined which proteins were preferentially synthesized. Putrescine stimulated the synthesis of ribosomal protein S1 markedly, but stimulated ribosomal proteins S4, L20, and X1, and RNA polymerase slightly. The amounts of initiation factors 2 and 3 synthesized were not influenced significantly by putrescine. The preferential stimulation of the synthesis of ribosomal protein S1 occurred as early as 20 min after the addition of putrescine, while stimulation of the synthesis of the other ribosomal proteins and RNA polymerase appeared at 40 min. The stimulation of the synthesis of ribosomal RNA also occurred at 40 min after addition of putrescine. Our results indicate that putrescine can stimulate both the synthesis and the activity of ribosomes. The increase in the activity of ribosomes was achieved by the association of S1 protein to S1-depleted ribosomes. The early stimulation of ribosomal protein S1 synthesis after addition of putrescine may be important for stimulation of cell growth by polyamines.
Aminoglycosides↗
Rescue of Sendai virus from viral ribonucleoprotein-transfected cells by infection with recombinant vaccinia viruses carrying Sendai virus L and P/C genes.
The Sendai virus ribonucleoprotein (RNP) showed only very low plaque-forming titers upon transfection and the virus yields after one-step growth were quite limited. We tried to enhance the Sendai virus yield by supplying the viral L and P/C gene products through vaccinia vectors. A combination of the recombinant vaccinia viruses carrying the L gene (Vac-HL) and the P/C gene (Vac-HPC), both of which were driven by the promoter of the vaccinia virus 7.5K protein gene, enhanced the yield only a little whereas another combination of Vac-HLd7.5, the L gene insert of which was driven by the promoter of the vaccinia virus thymidine kinase gene in place of the 7.5K promoter, and Vac-HPC greatly enhanced the Sendai virus yield. This seemed to correlate with the fact that the Vac-HL interfered with Sendai virus growth markedly while the Vac-HLd7.5 did not. These results strongly suggest that the L and P/C gene products act in cooperation as the RNA polymerase, and overproduction of the L protein is inhibitory for Sendai virus growth. This system seems to be of value as a tool for analyzing the functions of L and P/C genes of Sendai virus.
Animals↗
Induction of twinning in crossbred heifers by ipsilateral frozen embryo transfer.
Induction of twinning by means of nonsurgical ipsilateral transfer of two frozen embryos or of demi-embryos was attempted in 297 virgin crossbred dairy heifers that were kept at the following locations: in stables at our breeding station (Group 1), in a mountain field (Group 2) and at a private farm (Group 3). Of these, 187 heifers (63%) were diagnosed pregnant at 25 d after embryo transfer and 134 heifers (45%) were diagnosed pregnant at 60 d after transfer by ultrasonic echography or by palpation per rectum. At calving, 118 heifers produced 46 sets of twins and 72 single calves, for a total of 164 calves sixteen pregnant heifers aborted fetuses between 2 and 7 mo. The pregnancy rate of Group 1 (39%) was lower than that of Group 2 (48%) or Group 3 (50%). Abortion and mortality rates for Group 3 (8% and 8%, respectively) were significantly lower (P<0.05) than for Group 1 (16% and 12%) or Group 2 (13% and 18%). Twin calves had lower birth weights (P<0.05) than singles, but at 270 to 330 d of age, there was no significant difference between the weights of single and twin calves. Dystocia or difficult delivery was not observed heifers producing twins. Retention of the placenta was observed in twin calving heifers, with placenta retention levels the highest in Group 2 (33%) than followed by Group 1 (14%) and Group 3 (10%). When gestation periods were compared between single and twin calves in Groups 1 and 2, the gestation period of single calves was 5.0 to 7.0 d shorter than that of twin calves. No significant difference was observed between the gestation periods of single and twin births in Group 3.
Journal Article↗