Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu-A spinning top-shaped rubble pile

The Hayabusa2 spacecraft arrived at the near-Earth carbonaceous asteroid 162173 Ryugu in 2018. We present Hayabusa2 observations of Ryugu's shape, mass, and geomorphology. Ryugu has an oblate "spinning top" shape, with a prominent circular equatorial ridge. Its bulk density, 1.19 ± 0.02 grams per cubic centimeter, indicates a high-porosity (>50%) interior. Large surface boulders suggest a rubble-pile structure. Surface slope analysis shows Ryugu's shape may have been produced from having once spun at twice the current rate. Coupled with the observed global material homogeneity, this suggests that Ryugu was reshaped by centrifugally induced deformation during a period of rapid rotation. From these remote-sensing investigations, we identified a suitable sample collection site on the equatorial ridge.

The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes

The near-Earth carbonaceous asteroid 162173 Ryugu is thought to have been produced from a parent body that contained water ice and organic molecules. The Hayabusa2 spacecraft has obtained global multicolor images of Ryugu. Geomorphological features present include a circum-equatorial ridge, east-west dichotomy, high boulder abundances across the entire surface, and impact craters. Age estimates from the craters indicate a resurfacing age of [Formula: see text] years for the top 1-meter layer. Ryugu is among the darkest known bodies in the Solar System. The high abundance and spectral properties of boulders are consistent with moderately dehydrated materials, analogous to thermally metamorphosed meteorites found on Earth. The general uniformity in color across Ryugu's surface supports partial dehydration due to internal heating of the asteroid's parent body.

AIM-deficient mouse fed a high-trans fat, high-cholesterol diet: a new animal model for nonalcoholic fatty liver disease

Owing to changes in lifestyle, nonalcoholic fatty liver disease (NAFLD) is becoming a common form of chronic liver injury. NAFLD comprises a wide variety of disease stages, from simple steatosis to nonalcoholic steatohepatitis, which is a risk factor for the development of hepatocellular carcinoma (HCC). Because animal models for NAFLD are needed to investigate the precise pathogenesis, we aimed to establish a new mouse model employing mice deficient for apoptosis inhibitor of macrophage (AIM^−/−), which exhibit accelerated lipid storage in the liver and high susceptibility to developing HCC in response to a high-fat diet (HFD). AIM^−/− mice were fed the D09100301 diet, which contains 40 kcal% fat (trans fat 30 kcal%), high cholesterol (2%), and 40 kcal% carbohydrates (20 kcal% fructose), and then features of obesity and NAFLD including steatosis, inflammation, fibrosis, and HCC development were analyzed. Although a comparable grade of liver steatosis was promoted in AIM^−/− mice by the D09100301 diet and the standard HFD (60 kcal% largely lard fat), significantly less lipid storage in visceral fat was observed when the mice were fed the D09100301 diet. Accelerated liver inflammation was promoted by the D09100301 diet compared with the HFD, but interestingly, HCC development was decreased in mice fed the D09100301 diet. Our findings suggest that AIM^−/− mice fed the D09100301 diet exhibited a phenotype that resembled nonobese NAFLD patients and thus could be an appropriate tool to study the pathophysiology by which obesity increases the risk of HCC.

Independent modes of disease repair by AIM protein distinguished in AIM-felinized mice

Tissue macrophage-derived apoptosis inhibitor of macrophage (AIM, encoded by cd5l gene) is a circulating protein that has suppressive functions in a broad range of diseases including obesity, liver steatosis, hepatocellular carcinoma (HCC), and acute kidney injury (AKI). In healthy states, high levels of AIM circulate in the inactivated state by associating with the immunoglobulin M (IgM) pentamer in the blood, whereas during AKI, AIM dissociates from IgM and gains disease repair activity. Here, we assessed whether AIM activation via its release from IgM is required to ameliorate other diseases. To this end, we employed a mouse line in which mouse AIM was replaced with feline AIM (AIM-felinized mice). Because feline AIM rarely dissociates from IgM due to its extremely high binding affinity for IgM, these mice exhibited deficient AKI repair as in cats. When fed a high-fat diet (HFD), similar to AIM-deficient (AIM^−/−) mice, AIM-felinized mice exhibited enhanced triacylglycerol deposition in visceral adipocytes and hepatocytes, resulting in more prominent obesity and fatty liver than in wild-type mice. In contrast, the incidence of HCC after a 1-year HFD was remarkably lower in AIM-felinized mice than in AIM^−/− mice, suggesting that AIM produced by liver Kupffer macrophages might directly facilitate the elimination of HCC cells. Accordingly, the marked deposition of AIM accompanied by accumulation of Kupffer cells was obvious during HCC tumour development in AIM-felinized mice. Δsµ mice, which harbour almost no circulating AIM due to the lack of secreted IgM, showed a phenotype comparable with that of AIM-felinized mice in prevention of those diseases. Thus, blood AIM released from IgM contributes to suppression of obesity and fatty liver as in AKI, whereas macrophage-derived noncirculating AIM mainly prevents HCC development. Our study depicted two different modes of disease prevention/repair facilitated by AIM, which could be the basis for HCC therapy that works by increasing AIM expression in macrophages.

HTLV-1 Tax Induces Formation of the Active Macromolecular IKK Complex by Generating Lys63- and Met1-Linked Hybrid Polyubiquitin Chains

The Tax protein of human T-cell leukemia virus type 1 (HTLV-1) is crucial for the development of adult T-cell leukemia (ATL), a highly malignant CD4+ T cell neoplasm. Among the multiple aberrant Tax-induced effects on cellular processes, persistent activation of transcription factor NF-κB, which is activated only transiently upon physiological stimulation, is essential for leukemogenesis. We and others have shown that Tax induces activation of the IκB kinase (IKK) complex, which is a critical step in NF-κB activation, by generating Lys63-linked polyubiquitin chains. However, the molecular mechanism underlying Tax-induced IKK activation is controversial and not fully understood. Here, we demonstrate that Tax recruits linear (Met1-linked) ubiquitin chain assembly complex (LUBAC) to the IKK complex and that Tax fails to induce IKK activation in cells that lack LUBAC activity. Mass spectrometric analyses revealed that both Lys63-linked and Met1-linked polyubiquitin chains are associated with the IKK complex. Furthermore, treatment of the IKK-associated polyubiquitin chains with Met1-linked-chain-specific deubiquitinase (OTULIN) resulted in the reduction of high molecular weight polyubiquitin chains and the generation of short Lys63-linked ubiquitin chains, indicating that Tax can induce the generation of Lys63- and Met1-linked hybrid polyubiquitin chains. We also demonstrate that Tax induces formation of the active macromolecular IKK complex and that the blocking of Tax-induced polyubiquitin chain synthesis inhibited formation of the macromolecular complex. Taken together, these results lead us to propose a novel model in which the hybrid-chain-dependent oligomerization of the IKK complex triggered by Tax leads to trans-autophosphorylation-mediated IKK activation.

Critical behavior of a random diode network

We study the percolation properties of a random diode network (RDN) which contains two kinds of directed bonds on a square lattice. This network is a special case of the random insulation-resistor-diode network. Both Monte Carlo simulations and series expansion for the percolation probability show that an estimated critical exponent, beta=0.1794+/-0.008, is different from known values for a conventional insulation-resistor-diode network. RDN belongs to neither the isotropic percolation universality class nor to the directed percolation universality, which we attribute to a difference of symmetry breakdown around the critical point.

Developmental pattern of gentamicin kinetics in very low birth weight (VLBW) sick infants

Kinetic studies were carried out in 15 very low birth weight (VLBW) infants during three courses of gentamicin (G) therapy for suspected sepsis. All received two courses but only 6 required a third course. G dosage was 2.0 +/- 0.2 mg/kg/24 h for the first and second course and 2.5 mg/kg/12 h for the third course. G dosage was adjusted to maintain serum peak G concentration of 4-8 micrograms/ml and trough concentration of 0.5-2 micrograms/ml. On the third day of therapy, a 24-hour collection of urine for creatinine (C) and G concentrations was performed in 28 of 36 cases. G clearance and G elimination rate constant were calculated based on chronological age (CA) of less than or equal to 7 (I), 8-30 (II) and greater than or equal to 31 (III) days. The mean BW and GA were 1,002 +/- 206 g and 28.4 +/- 1.5 weeks, respectively. Mean CA for the starting of therapy for each course was the first day, 19 +/- 9 and 68 +/- 26 days of life, respectively. Mean serum G peak and trough concentrations were 5.9 +/- 1.1 and 1.6 +/- 0.6 micrograms/ml for the first; 5.7 +/- 1.2 and 1.3 +/- 0.6 micrograms/ml for the second; 5.1 +/- 0.8 and 1.1 +/- 0.6 micrograms/ml for the third course of therapy. Mean apparent volume of distribution of G were 0.53 +/- 0.10 liter/kg for the first and 0.50 +/- 0.11 liter/kg for the second and third courses. Mean clearances for the three CA groups were 6.4 +/- 1.9; 7.6 +/- 3.2; 24.1 +/- 8.0 ml/min/1.73 m2 for G and 6.4 +/- 2.2; 7.7 +/- 3.1; 23.3 +/- 8.8 for C with serum C of 1.3 +/- 0.4, 1.2 +/- 0.6 and 0.6 +/- 0.4 mg%, respectively. There were no statistically significant differences for serum C, G and C clearance between CA I and II but significant differences were found for the above between CA III vs. CA I and II (p less than 0.005). G clearance closely correlated with C clearance (r = 0.99, p less than 0.001). The elimination rate constant was significantly higher after 30 days of life when CA III is compared to CA I and II or combined (p less than 0.001). This study shows that during the first month of life, VLBW sick infants still have decreased renal function and poor G clearance, therefore, G should be given every 24 h and the dose be adjusted based on individual patient serum G levels.

Large-for-gestational-age neonates: anthropometric reasons for shoulder dystocia

From 1960 to 1980 at Memorial Hospital Medical Center--Miller Children's Hospital, the mean birth weight for term-size neonates increased from 3381 to 3458 g inspite of increases in ethnic groups known to have smaller neonates. More significantly, the incidence of macrosomic neonates (birth weight greater than 4000 g) increased from 7.0 to 10.7%. Because of this marked increase in the incidence of neonatal macrosomia, prospective study was designed to characterize the macrosomic neonate anthropometrically. The results of this study revealed that neonates experiencing shoulder dystocia had significantly greater shoulder-to-head and chest-to-head disproportions than did macrosomic neonates delivered by cesarean section for failed progress in labor or macrosomic neonates delivered without shoulder dystocia. In addition, neonates of diabetic mothers also showed significantly greater shoulder-head and chest-head size differences than did neonates of nondiabetic mothers of comparable weight. These data suggest that antenatal ultrasonic measurements to compare chest-head size difference in fetuses suspected to be macrosomic and in diabetic pregnancies could be of value in selecting patients for the appropriate route of delivery.