Discovery of

The new isotope ^{39}Na, the most neutron-rich sodium nucleus observed so far, was discovered at the RIKEN Nishina Center Radioactive Isotope Beam Factory using the projectile fragmentation of an intense ^{48}Ca beam at 345 MeV/nucleon on a beryllium target. Projectile fragments were separated and identified in flight with the large-acceptance two-stage separator BigRIPS. Nine ^{39}Na events have been unambiguously observed in this work and clearly establish the particle stability of ^{39}Na. Furthermore, the lack of observation of ^{35,36}Ne isotopes in this experiment significantly improves the overall confidence that ^{34}Ne is the neutron dripline nucleus of neon. These results provide new key information to understand nuclear binding and nuclear structure under extremely neutron-rich conditions. The newly established stability of ^{39}Na has a significant impact on nuclear models and theories predicting the neutron dripline and also provides a key to understanding the nuclear shell property of ^{39}Na at the neutron number N=28, which is normally a magic number.

Swelling of Doubly Magic

Interaction cross sections for ^{42-51}Ca on a carbon target at 280 MeV/nucleon have been measured for the first time. The neutron number dependence of derived root-mean-square matter radii shows a significant increase beyond the neutron magic number N=28. Furthermore, this enhancement of matter radii is much larger than that of the previously measured charge radii, indicating a novel growth in neutron skin thickness. A simple examination based on the Fermi-type distribution, and mean field calculations point out that this anomalous enhancement of the nuclear size beyond N=28 results from an enlargement of the core by a sudden increase in the surface diffuseness of the neutron density distribution, which implies the swelling of the bare ^{48}Ca core in Ca isotopes beyond N=28.

Location of the Neutron Dripline at Fluorine and Neon.

A search for the heaviest isotopes of fluorine, neon, and sodium was conducted by fragmentation of an intense ^{48}Ca beam at 345 MeV/nucleon with a 20-mm-thick beryllium target and identification of isotopes in the large-acceptance separator BigRIPS at the RIKEN Radioactive Isotope Beam Factory. No events were observed for ^{32,33}F, ^{35,36}Ne, and ^{38}Na and only one event for ^{39}Na after extensive running. Comparison with predicted yields excludes the existence of bound states of these unobserved isotopes with high confidence levels. The present work indicates that ^{31}F and ^{34}Ne are the heaviest bound isotopes of fluorine and neon, respectively. The neutron dripline has thus been experimentally confirmed up to neon for the first time since ^{24}O was confirmed to be the dripline nucleus nearly 20 years ago. These data provide new keys to understanding the nuclear stability at extremely neutron-rich conditions.

Discovery of

The discovery of the important neutron-rich nucleus _{20}^{60}Ca_{40} and seven others near the limits of nuclear stability is reported from the fragmentation of a 345 MeV/u ^{70}Zn projectile beam on ^{9}Be targets at the radioactive ion-beam factory of the RIKEN Nishina Center. The produced fragments were analyzed and unambiguously identified using the BigRIPS two-stage in-flight separator. The eight new neutron-rich nuclei discovered, ^{47}P, ^{49}S, ^{52}Cl, ^{54}Ar, ^{57}K, ^{59,60}Ca, and ^{62}Sc, are the most neutron-rich isotopes of the respective elements. In addition, one event consistent with ^{59}K was registered. The results are compared with the drip lines predicted by a variety of mass models and it is found that the models in best agreement with the observed limits of existence in the explored region tend to predict the even-mass Ca isotopes to be bound out to at least ^{70}Ca.

Optimizing production of in vivo-matured oocytes from superstimulated Holstein cows for in vitro production of embryos using X-sorted sperm.

The present study aimed to establish an efficient system for the production of female embryos from dairy cows by in vitro fertilization (IVF) using X-sorted sperm and in vivo-matured oocytes collected by ovum pick up (OPU). Nonlactating Holstein cows (n = 36) were administered a controlled intravaginal progesterone-releasing (controlled internal drug release) device (d 0), underwent dominant follicle ablation (DFA) or ovulation by administration of 100 µg of GnRH on d 5, and were superstimulated with FSH and PGF2α, following standard procedures. Controlled internal drug release devices were removed on the evening of d 8 or on the morning of d 9, depending on the experiment. For LH surge induction, 200 µg of GnRH was administered on the morning of d 10 (0 h). In experiment 1, the peak (48.1%) of ovulating follicles was detected at 29 to 32 h after GnRH injection (0 h), and the range in the timing of the initiation of ovulation was less by timing from GnRH administration (30.0 ± 2.8h) rather than by timing the onset of estrus (32.7 ± 4.7h). Only 0.9% of total ovulated follicles were recorded before 26 h after GnRH injection. Therefore, OPU was carried out at 26 h and IVF occurred at 30 h after GnRH in experiments 2 and 3. In experiment 2, 83.3 ± 10.8% of oocytes with expanded cumulus cells had extruded the first polar body at 30 h after GnRH injection. The aim of experiment 3 was to compare the effect of either DFA or GnRH-induced LH surge before superstimulation on the efficiency of embryo production by IVF following superstimulation. Progesterone concentrations from d 10 to 12 in the DFA group were lower than those in the GnRH group. A greater proportion of recovered oocytes with expanded cumulus cells from ≥ 8-mm follicles was observed in the DFA group than in the GnRH group (95.9 and 77.4%, respectively). Blastocyst rates in the DFA and GnRH groups (58.0 and 52.8%, respectively) did not differ from those of oocytes collected from nonstimulated OPU and matured in vitro (49.9%). However, the proportion of high-quality blastocysts was higher in the DFA group compared with the GnRH group (54.9 vs. 21.5%). Our results demonstrate that high rates of good-quality blastocysts can be produced by IVF with X-sorted frozen sperm using in vivo-matured oocytes collected by OPU from cows after DFA and superstimulation combined with ovulation induction.

Culture of bovine embryos in polyester mesh sections: the effect of pore size and oxygen tension on in vitro development.

The purpose of this study was to assess the feasibility of polyester mesh culture for the in vitro production of bovine embryos, as polyester mesh is an alternative way for tracking individual embryos throughout culture using time-lapse cinematography (TLC). Bovine embryos were isolated during in vitro culture using sections of three different polyethylene terephthalate (PET) mesh products. In vitro matured and fertilized bovine oocytes were cultured in the 217 × 217, 230 × 230 or 238 × 238-µm openings of PET mesh sections or in simple micro-drops (control) for 7 days under either 20% or 5% O(2) tensions. No difference in embryo developmental rates was found between the culture groups in terms of cleavage, blastocyst formation and blastocyst expansion irrespective of O(2) tension. In contrast, under 20% O(2) tension, blastocysts that developed in PET mesh with 217 × 217-µm opening had significantly higher numbers of total and trophectoderm (TE) cells than control embryos; however, the numbers and proportions of inner cell mass (ICM) cells did not differ. Under 5% O(2) tension, no difference was found among the culture groups in the numbers of total, ICM and TE cells in embryos. All three PET mesh products investigated in this study were proven to be effective to prevent embryo movement. The results demonstrate that bovine embryos can be cultured in PET mesh sections without negative side-effects and suggest that embryo distance determined by the mesh affects embryo quality at atmospheric oxygen tension. Polyethylene terephthalate mesh with 217 × 217-µm openings was found to be the most suitable for further application in TLC.

Halo structure of the island of inversion nucleus 31Ne.

The cross sections for single-neutron removal from the very neutron-rich nucleus 31Ne on Pb and C targets have been measured at 230 MeV/nucleon using the RIBF facility at RIKEN. The deduced large Coulomb breakup cross section of 540(70) mb is indicative of a soft E1 excitation. Comparison with direct-breakup model calculations suggests that the valence neutron of 31Ne occupies a low-l orbital (most probably 2p(3/2)) with a small separation energy (S(n) approximately < 0.8 MeV), instead of being predominantly in the 1f(7/2) orbital as expected from the conventional shell ordering. These findings suggest that 31Ne is the heaviest halo system known.

The surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy.

The near-Earth asteroid 162173 Ryugu, the target of the Hayabusa2 sample-return mission, is thought to be a primitive carbonaceous object. We report reflectance spectra of Ryugu's surface acquired with the Near-Infrared Spectrometer (NIRS3) on Hayabusa2, to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micrometers was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, which is consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Hypercalcemia in childhood acute lymphoblastic leukemia: frequent implication of parathyroid hormone-related peptide and E2A-HLF from translocation 17;19.

Hypercalcemia is relatively rare but clinically important complication in childhood leukemic patients. To clarify the clinical characteristics, mechanisms of hypercalcemia, response to management for hypercalcemia, incidence of t(17;19) and final outcome of childhood acute lymphoblastic leukemia (ALL) accompanied by hypercalcemia, clinical data of 22 cases of childhood ALL accompanied by hypercalcemia (>12 mg/dl) reported in Japan from 1990 to 2005 were retrospectively analyzed. Eleven patients were 10 years and older. Twenty patients had low white blood cell count (<20 x 10(9)/l), 15 showed hemoglobin> or =8 g/dl and 14 showed platelet count > or =100 x 10(9)/l. Parathyroid hormone-related peptide (PTHrP)-mediated hypercalcemia was confirmed in 11 of the 16 patients in whom elevated-serum level or positive immunohistochemistry of PTHrP was observed. Hypercalcemia and accompanying renal insufficiency resolved quickly, particularly in patients treated with bisphosphonate. t(17;19) or add(19)(p13) was detected in five patients among 17 patients in whom karyotypic data were available, and the presence of E2A-HLF was confirmed in these five patients. All five patients with t(17;19)-ALL relapsed very early. Excluding the t(17;19)-ALL patients, the final outcome of ALL accompanied by hypercalcemia was similar to that of all childhood ALL patients, indicating that the development of hypercalcemia itself is not a poor prognostic factor.

Salivary gland weight and nerve growth factor in the genetically obese (ob/ob) mouse.

The salivary glands of genetically obese male mice are significantly smaller than those of lean male mice, but the salivary glands of female mice do not differ in weight. The increases in weight of salivary glands in male mice after treatment with T3 at 50, 150, or 500 ng/day or with several doses of isoproterenol were comparable on a percentage basis, but the weights in the ob/ob mice were always smaller than any of those in the lean mice. Measurements of nerve growth factor (NGF) in several tissues showed a significantly lower concentration in the salivary glands of obese female mice than in same tissue from female lean mice. There were no differences in NGF levels in brown fat or in the cortex, cerebellum, or brain stem. The concentration of epidermal growth factor, in contrast to that of NGF, was not lower in the salivary glands of obese mice. Testosterone increased the weight of the salivary glands, spleen, and kidney in obese female mice, but the weight of the salivary glands in lean animals remained significantly higher than that in the obese mice both with and without treatment. Testosterone significantly increased the NGF concentration in salivary glands, but the values in treated male mice were only one tenth those in the treated lean animals.

Orally administered prostaglandin E1 derivative can enhance liver regeneration in partially hepatectomized rats.

The effect of orally administered 17(S),20-dimethyl-6-oxo prostaglandin E1 (PGE1) methyl ester (OP) on liver regeneration was examined in 66% hepatectomized rats. Administration of OP increased the mitotic index of the hepatocyte 3 days after hepatectomy, and the mitotic index response due to OP was dose dependent. The OP administration had no effect on food intake, but reduced water intake. The serum scores relative to nutrition and hepatic function showed transient change after OP administration, whereas the serum blood urea nitrogen level indicated a slight renal dysfunction with OP. The fat store in the body was transiently reduced. These observations lead us to conclude that orally administered OP is capable of stimulating liver regeneration without serious systemic effects.

A device for expressing the serum insulin glucose relationship in diabetes, hyper- or hypothyroidsm, and chronic hepatitis.

When the serum insulin valves during a 50-gm oral glucose tolerance test were expressed as the function of glucose concentrations, a good linear relationship was found in normal subjects and in patients with diabetes, hyperthroidism, hypothroidism or chronic hepatitis. The insulin index calculated from the line representing this relationship was less than 100 in all 19 diabetic patients and most of the 13 hyperthyroid patients with oxyhyperglycemia, whereas it was more than 100 in the 14 normal subjects, the 4 hypothyroid patients, and the 8 patients with oxyhyperglycemia due to chronic hepatitis. The insulin index decreased with increasing maximal blood glucose concentration during the glucose tolerance test in diabetic patients. Furthermore, improvement in the insulin index was correlated with the effectiveness of sulfornylurea drugs in the diabetic group.

Secretion of gastric acid inhibited by oxytocin injected into the hypothalamic paraventricular nucleus in the rat.

Gastric acid output was examined following oxytocin injection into the hypothalamic paraventricular nucleus (PVN) or into the vagus nucleus (X) of the medulla in rats with insulin-hypoglycemia. Gastric acid output was reduced following the injection of nanomolar quantities of oxytocin into these nuclei, and the response was dose-dependent. It was also noted that there was a synergistic action on the response by the peptide between PVN and X. The acid response was blocked by section of the vagus nerve at the subdiaphragmatic level or by prior administration of atropine sulfate. These observations suggest that oxytocin in the PVN is active in suppressing gastric acid secretion, and the vagal response is characteristic of activation of the PVN and X.

Gastrin-17 injected into the hypothalamic paraventricular nucleus can induce gastric acid secretion in rats.

Injections of picomolar quantities of gastrin-17 into the hypothalamic paraventricular nucleus increased gastric acid output in anesthetized rats. The response was dose-dependent, and it was blocked by atropin and by vagotomy. The same doses, injected intravenously, intraventriculary or into sites far from the nucleus, did not increase the output. Cholecystokinin-8 injected into the nucleus had no effect on the acid output.

Inhibition of gastric motility induced by activation of the hypothalamic paraventricular nucleus.

Electrical stimulation of the paraventricular nucleus depressed the intragastric pressure of adrenalectomized male rats of which gastric movement had been induced by insulin-hypoglycemia. Electrical stimulation to the pituitary stalk produced a similar response in the pressure, but the response was abolished by bilateral lesion of the paraventricular nucleus. These findings allow us to speculate that the paraventricular nucleus is capable of modulating gastric motility, and suggest that the nucleus has a neural connection between the neurohypophysis and the system relevant to visceral function.

Enhanced gastric acid secretion induced by gastrin can be suppressed partially by glucose injection into the medullary nuclei in rats.

Gastric acid outputs after glucose injection into the nucleus of the vagus nerve (X) or into the nucleus of the tractus solitarius (SOL) were examined in rats with tetragastrin. The enhanced acid output caused by gastrin was partially inhibited by glucose injection into the X or SOL. Glucose injection into the X depressed acid output in a dose-dependent fashion, but a non-dose-dependent response in acid output was seen when glucose was injected into the SOL. There was no interaction between the X and SOL in acid response due to glucose. These findings suggest that glucose modulates gastric acid secretion stimulated by gastrin at the medullary level, and that such a modulation is characterized by the medullary X or SOL, separately.

D-glucose anomers in the nucleus of the vagus nerve can depress gastric motility of rats.

The infusion of alpha-,beta-, or equilibrated (alpha: 36%; beta: 64%) D-glucose solution in the vicinity of the nucleus of the vagus nerve decreased gastric motility caused by insulin in rats with bilateral adrenalectomy. This effect was not reproduced after vagotomy at the cervical level. Of the 3 forms of D-glucose solution the effect of beta-D-glucose was greatest. The infusion of isotonic NaCl, however, produced no change in the motility. These results suggest that blood beta-D-glucose may predominantly activate a brain mechanism which vagally controls gastric motility at the medullary level.

Alterations in gastric acid secretion following hepatic vagotomy at a stage of development in rats.

The relation of gastric acid secretion to the hepatic vagal section was examined in consideration of developmental stages of a rat. Acid outputs in rats deprived of food for 22 hr before the experiment were estimated with or without insulin. The animals were classified into five groups according to their body weights at the experiments (50, 100, 200, 300 and 400 g). Hepatic vagotomy was effective in decreasing acid output in all of the groups treated with food deprivation and insulin, and it was found that there was a close relationship between the output and glucose concentration in the portal blood. In rats treated only with food deprivation, hepatic vagotomy produced different effects for the five groups; the vagotomy failed to cause acid response when the rats weighed about 300 and 400 g, while in the animals weighing about 50, 100 and 200 g acid outputs were reduced following the vagotomy. It was noted that the sensitivity to hypoglycemia in the acid output was greater in the young rats than the older ones. Results suggest that function of the hepatic vagal nerve may be prominent in modulating acid secretion in an earlier stage of development when the animals are most sensitive to hypoglycemia.

Simultaneous development of Crohn's disease and myelodysplastic syndrome progressing to acute myelocytic leukemia in a patient with a normal karyotype.

A 28-year-old man developed Crohn's disease and myelodysplastic syndrome concurrently. Chromosomal analysis of the bone marrow revealed a normal male karyotype. Subsequently, the myelodysplastic syndrome progressed to acute myelocytic leukemia. Several causes, including the medical treatment for Crohn's disease, chromosomal abnormalities, and a common underlying immune dysfunction, have been proposed as pathogenetic factors in the association with Crohn's disease of hematologic malignancies. This case suggests that neither medical treatment for Crohn's disease nor chromosomal abnormalities are inevitable causes of the development of hematologic malignancies associated with Crohn's disease. At present, the cause of the association remains unclear, although the idea of a common immune dysfunction is attractive.

Interaction of glucose signals between the nucleus of the vagus nerve and the portal vein area in the regulation of gastric motility in rats.

Intragastric pressures were examined after glucose injection into the nucleus of the vagus nerve (X) of the medulla oblongata or into the portal vein (PV) or both in bilaterally adrenalectomized rats. Ten mM glucose (500 nl) injected into the X or into the PV (25 microliters) decreased gastric pressure associated with insulin-hypoglycemia. Simultaneous injection of glucose into the X and PV produced a reduction in gastric pressure in an additive manner. In addition, a significant fall in gastric pressure was seen when an ineffective concentration of glucose was injected into the X and PV simultaneously. The results suggest that the X and PV signals interact with each other to inhibit gastric motility.