Color, composition, and thermal environment of Kuiper Belt object (486958) Arrokoth.

The outer Solar System object (486958) Arrokoth (provisional designation 2014 MU69) has been largely undisturbed since its formation. We studied its surface composition using data collected by the New Horizons spacecraft. Methanol ice is present along with organic material, which may have formed through irradiation of simple molecules. Water ice was not detected. This composition indicates hydrogenation of carbon monoxide-rich ice and/or energetic processing of methane condensed on water ice grains in the cold, outer edge of the early Solar System. There are only small regional variations in color and spectra across the surface, which suggests that Arrokoth formed from a homogeneous or well-mixed reservoir of solids. Microwave thermal emission from the winter night side is consistent with a mean brightness temperature of 29 ± 5 kelvin.

The geology and geophysics of Kuiper Belt object (486958) Arrokoth.

The Cold Classical Kuiper Belt, a class of small bodies in undisturbed orbits beyond Neptune, is composed of primitive objects preserving information about Solar System formation. In January 2019, the New Horizons spacecraft flew past one of these objects, the 36-kilometer-long contact binary (486958) Arrokoth (provisional designation 2014 MU69). Images from the flyby show that Arrokoth has no detectable rings, and no satellites (larger than 180 meters in diameter) within a radius of 8000 kilometers. Arrokoth has a lightly cratered, smooth surface with complex geological features, unlike those on previously visited Solar System bodies. The density of impact craters indicates the surface dates from the formation of the Solar System. The two lobes of the contact binary have closely aligned poles and equators, constraining their accretion mechanism.

Impact craters on Pluto and Charon indicate a deficit of small Kuiper belt objects.

The flyby of Pluto and Charon by the New Horizons spacecraft provided high-resolution images of cratered surfaces embedded in the Kuiper belt, an extensive region of bodies orbiting beyond Neptune. Impact craters on Pluto and Charon were formed by collisions with other Kuiper belt objects (KBOs) with diameters from ~40 kilometers to ~300 meters, smaller than most KBOs observed directly by telescopes. We find a relative paucity of small craters ≲13 kilometers in diameter, which cannot be explained solely by geological resurfacing. This implies a deficit of small KBOs (≲1 to 2 kilometers in diameter). Some surfaces on Pluto and Charon are likely ≳4 billion years old, thus their crater records provide information on the size-frequency distribution of KBOs in the early Solar System.

Androgen insensitivity syndrome.

OBJECTIVE: We provide a review of the literature about the Androgen Insensitivity Syndrome (AIS), its onset and associated developmental anomalies and the genetic alterations causing it. MATERIALS AND METHODS: We searched PubMed with a larger emphasis on the physiology, genetics and current management of AIS. RESULTS: AIS is an X-linked recessive Disorder of Sex Development (DSD). It is caused by mutations of the Androgen Receptor, and their large amount and heterogeneity (missense and nonsense mutations, splicing variants, deletions, and insertions) are responsible for the wide spectrum of possible phenotypes of patients, divided into Partial AIS (PAIS) and Complete AIS (CAIS). Once the clinical and laboratory investigations have laid the foundation for a diagnostic hypothesis, it is important to identify the actual karyotype of the individual and search for the mutation in the Androgen Receptor to diagnose with certainty the syndrome. Alternatively, in the absence of such evidence, the diagnosis should more properly be an AIS-like condition, which we describe as well in our report. CONCLUSIONS: The management of this DSD is based on pharmacotherapies, surgery and psychological support: all of them must be directed to facilitate the patient's life, considering his/her sexual identity.

Vesicoureteral reflux in infants: what do we know about the gender prevalence by age?

OBJECTIVE: Vesicoureteral reflux (VUR) affects up to 1% of Caucasian children. Primary VUR is characterized by failure of the ureterovesicular junction to prevent urine from traveling in a retrograde fashion from the bladder to the ureters and the kidneys. Several reports in the literature describe the prevalence of this condition in pediatric patients; overall, VUR affects more males during infancy and with higher grades. However, a thorough consideration of these articles reveals important contradictions regarding the prevalence by gender and age. We analyzed those contradictions and suggested a possible explanation based on our single center experience with this patient group. In particular, for the age interval 0-2 years: we have found that (1) VUR mostly affects boys; (2) the male/female ratio steadily declines over time; (3) the unequal prevalence between males and females essentially disappears when children reach the age of two years. CONCLUSIONS: The natural history of VUR in infant boys differs from that of infant girls, and therefore requires a gender-specific approach. Available data support the need to redefine the categorization and clinical guidelines for this disease.

Surgical management of Necrotizing Enterocolitis in an Incredibly Low Birth Weight infant and review of the Literature.

Survival of preterm infants have dramatically improved over the last decades. Nonetheless, infants born preterm remain vulnerable to many complications, including necrotizing enterocolitis (NEC). The severity of the disease and the mortality rate are directly correlated with decreasing gestational age and birth weight. Despite surgical treatment mortality rate remains very high in extremely premature infants, especially in newborns at the lowest limit of viability. Survival of infants of birth weight (BW) below 750 g has been increasingly reported in recent years, however the overall mortality in extremely low "BW" infants (ELBW) requiring surgery for NEC has not decreased over the past years. We describe our experience with a male preterm infant who survived after an ileostomy procedure for Bell stage II NEC, with improving neuromotor skills at 2 years follow up. Although standard indication to surgery is Bell stage III, in our case the choice of minimal laparotomy, exploration of the bowel and ileostomy at Bell stage II was safe and effective. Our experience suggest that surgery has not a negative impact on survival and ileostomy could prevent further damage of the bowel in NEC. We hypothesize that indication to surgery at an earlier stage may prevent further progression of the disease without a significantly negative impact on survival. Further studies are needed to confirm the appropriateness of this approach in ELBW infants.

The formation of Charon's red poles from seasonally cold-trapped volatiles.

A unique feature of Pluto's large satellite Charon is its dark red northern polar cap. Similar colours on Pluto's surface have been attributed to tholin-like organic macromolecules produced by energetic radiation processing of hydrocarbons. The polar location on Charon implicates the temperature extremes that result from Charon's high obliquity and long seasons in the production of this material. The escape of Pluto's atmosphere provides a potential feedstock for a complex chemistry. Gas from Pluto that is transiently cold-trapped and processed at Charon's winter pole was proposed as an explanation for the dark coloration on the basis of an image of Charon's northern hemisphere, but not modelled quantitatively. Here we report images of the southern hemisphere illuminated by Pluto-shine and also images taken during the approach phase that show the northern polar cap over a range of longitudes. We model the surface thermal environment on Charon and the supply and temporary cold-trapping of material escaping from Pluto, as well as the photolytic processing of this material into more complex and less volatile molecules while cold-trapped. The model results are consistent with the proposed mechanism for producing the observed colour pattern on Charon.

Management of severe constipation in children.

AIM: Constipation is a common pediatric problem. Sometimes the hospitalization is necessary and in these patients the organic cause should be verified. The authors report their experience in the management of children with severe constipation. METHODS: Anorectal manometry (ARM) was performed after a careful examination of perineum and bowel disimpaction. Once organic cause had be excluded, the patient got medical therapy. If recto-anal inhibitory reflex (RAIR) was absent, not collaborative patient or medical treatment failed, the child underwent contrast enema (CE) and rectal suction biopsies (RSB). Local anesthetics were used for anal fissures or internal anal sphincter (IAS) hypertonia. Anal malformations and Hirschsprung's disease (HD) were surgically treated. Posterior sagittal anorectoplasty was performed for anal malformations. RESULTS: In 5 years 98 children (63 males) were observed (mean age 6 years). 5 children were premature for gestational age, 4 presented failure to thrive, 5 anal malformations and 45 anal fissures. ARM was performed in 87 children and 74 of them showed normal RAIR. Hypertonia of the IAS was recorded in 38 patients. RAIR was absent/unclear in 13 patients. Follow-up revealed 6 patients (negative to ARM) with poor results without oral laxative. CE was performed in 19 children (2 positive cases) and RBS in 25 patients (2 cases of HD). CONCLUSION: Children with severe constipation must be carefully observed and studied because of not negligible incidence of organic cause. The first step in the management of these patients is the evacuation of the fecaloma.

Size and albedo of Kuiper belt object 55636 from a stellar occultation.

The Kuiper belt is a collection of small bodies (Kuiper belt objects, KBOs) that lie beyond the orbit of Neptune and which are believed to have formed contemporaneously with the planets. Their small size and great distance make them difficult to study. KBO 55636 (2002 TX(300)) is a member of the water-ice-rich Haumea KBO collisional family. The Haumea family are among the most highly reflective objects in the Solar System. Dynamical calculations indicate that the collision that created KBO 55636 occurred at least 1 Gyr ago. Here we report observations of a multi-chord stellar occultation by KBO 55636, which occurred on 9 October 2009 ut. We find that it has a mean radius of 143 +/- 5 km (assuming a circular solution). Allowing for possible elliptical shapes, we find a geometric albedo of in the V photometric band, which establishes that KBO 55636 is smaller than previously thought and that, like its parent body, it is highly reflective. The dynamical age implies either that KBO 55636 has an active resurfacing mechanism, or that fresh water-ice in the outer Solar System can persist for gigayear timescales.

Severe congenital diaphragmatic hernia (CDH): a critical analysis of eight years' experience.

UNLABELLED: OBJECTIVES. 1) To define the best outcome of severe Congenital Diaphragmatic Hernia (CDH); 2) to critically evaluate deaths in order to identify possible criteria of exclusion from ECMO; and 3) to identify CDHs which could benefit from ECMO. MATERIALS AND METHODS: 63 severe CDHs, 35 (55.6 %) survivors and 28 (44.4 %) nonsurvivors, subdivided into 2 groups according to age at death: Group I dying at 12 < or = 24 hours, and Group II dying at > 24 hours after birth. The three groups were compared on the basis of prenatal diagnosis, polyhydramnios, gestational age, birth weight, pneumothorax, best values of postductal PaCO 2 and PaO 2, clinical and echocardiographic signs of persistent pulmonary hypertension, and severity of pulmonary hypoplasia (i.e., body weight to bilateral lung weight ratio at autopsy). RESULTS: PaCO 2, PaO 2 and degree of pulmonary hypoplasia were significantly worse in Group I compared to Group II and to survivors. PaCO 2 and PaO 2 in Group II did not differ significantly from those of survivors. CONCLUSIONS: In severe CDH it is possible: 1) to achieve a survival rate of 56 % without ECMO; 2) to identify a group of patients (Group I = 27 %) with severe pulmonary hypoplasia who would probably die even with ECMO; and 3) to identify a group of patients (Group II = 17 %) who might benefit from ECMO treatment.

An experimental animal model of intestinal obstruction to simulate in utero therapy for jejunoileal atresia.

OBJECTIVE: To obtain 'intestinal atresia-like' conditions in the fetal lamb model to subsequently allow in utero surgical repair. METHODS: Six time-dated pregnant sheep underwent general anesthesia at 75 days of gestation (term 145 +/- 5 days). After maternal laparotomy and hysterotomy, the fetal abdomen was opened. Once the jejunoileal intestinal loop was identified, the mesenteric vessels were isolated, ligated, and sectioned in 2 fetuses, and in the remaining 5 fetuses the bowel loop was ligated. Two further fetuses were used as controls and underwent sole laparotomy. Of the group of 7 fetuses 2 were reoperated at 100-105 days of gestational age and underwent intestinal recanalization. Eight fetuses were delivered at term by cesarean section and the remaining 1 by spontaneous delivery. One newborn underwent neonatal entero-enteric anastomosis. RESULTS: 4 out of 6 fetuses survived, in utero intestinal or vascular ligation having provoked an 'intestinal atresia-like' picture. The animal operated at birth died. The 2 control fetuses and the 2 fetuses with in utero intestinal recanalization survived until term. CONCLUSION: The present study shows that in utero treatment of intestinal obstruction is possible in an experimental model.

[Peripheral neuroectodermal tumors of the chest wall. Description of a case]. / Tumori neuroectodermici periferici della parete toracica. Descrizione di un caso.

The authors discuss a case of malignant small round cell tumor of the thoracopulmonary region (Askin tumor) in which the initial pathological diagnosis was "sarcoma". Only a review of the histological specimens and the clinical features and evolution revealed the correct diagnosis of "Askin tumor". A 15 year old girl with fever, dyspnoea, cough underwent thoracentesis, which revealed hemothorax. At surgery, a large mass not involving the lung, with pleural thickening, was found in the left hemithorax and excised, without rib resection. No metastasis was observed at that time. Histological findings revealed features of malignant small round cell tumors, with occasional pseudo-rosettes. Chemotherapy was performed. 16 months after clinical presentation the girl died with abdomino-thoracic metastatic disease.

Growth in children following liver transplantation.

Although liver transplantation (OLT) has become standard therapy for end-stage liver disease in children, growth after OLT remains an area of concern. We reviewed our experience with growth after OLT at the Hospital for Sick Children in 83 patients who survived at least 1 yr post-transplant. Our aims were to describe the success rate in steroid cessation in patients after transplantation, to examine the effect of transplantation on subsequent growth, to see if steroid reduction had a beneficial effect on growth, and to quantify the risk of stopping steroids on rejection. Patients below age 5 yr were weaned off steroids more easily than those over age 5: 19.2% vs. 0% (p<0.05), 65.9% vs. 50%, and 79.5% vs. 37.5% (p<0.05) at post-transplant years 1, 2, and 3, respectively. Pre-transplant, 30% of patients were below the third percentiles for height and weight. Post-transplant, there was a steady improvement in the distribution of patients above the 3rd percentile, so that by post-transplant year 6, only 5% were below the 3rd percentile. Height and height velocity percentiles were found to correlate inversely with total yearly steroid dose (mg/kg) at post-transplant years 2, 3 and 6 (p<0.05). In 60% of patients, steroids were successfully discontinued. In these patients, height and height velocity percentiles have achieved a near normal distribution with 40% and 46% of patients above the 50th percentile for height and height velocity percentiles, respectively. No grafts were lost to rejection in those off steroids, and all rejection episodes were easily reversed. We conclude that the majority of children can be weaned off steroids successfully after OLT and that growth in those children in the presence of good graft function is near normal.

In utero partial liver resection in the rabbit model: a study on fetal tissue regeneration.

In this study we developed a model of in vivo intrauterine partial liver resection in the fetal rabbit to analyze fetal liver regeneration. After intravenous anesthesia, 12 time-dated pregnant, California rabbits underwent a midline laparotomy and minimal hysterotomy at 24-25 days of gestational age. One fetus was exposed from each pregnant doe and the fetal liver was partially resected. Cesarean sections were performed 24, 48 and 72 h and 4 days after surgery. Three fetuses operated at 24 days of gestational age and 3 fetuses operated at 25 days were alive at retrieval. The fetuses and the sampled livers were weighed at retrieval and fetal liver weight showed a well-maintained value in all cases. Fetal livers were processed for the common histologic stains. Lymphocytes, polymorphonuclear leukocytes and phagocytes were counted from sections obtained in areas close to the edge of resection. Inflammatory cells showed a peculiar pattern of infiltration at different stages of repair, with a constantly increased number of phagocytes peaking 48 h after resection. Fetal liver seems to present a specific pattern of repair that differs from both the adult liver and other fetal tissues healing after injury.

[Hepatic resection in the fetal rabbit. Histologic comparison of tissue regeneration in the fetus versus the adult]. / Resezione epatica fetale nel coniglio. Confronto istologico della rigenerazione tissutale del feto e dell'adulto.

Fetal tissues present peculiar features of repair after injury. Although the development of fetal hepatocytes have already been studied in vitro and in transplant models, an in vivo study of fetal liver regeneration is still missed in the literature, to the best of our knowledge. Eight time-dated pregnant California rabbits (23, 24, 25, 30 days of gestational age) and 2 adult male California rabbits were anesthetized following a standardized i.v. protocol (ketamine 50 mg/kg; xilazine 5 mg/kg; propiopromazine 0.75 mg/kg; spontaneous breathing; no anesthetic gas). All the pregnant does underwent a midline laparotomy and a minimal hysterotomy to approach a fetus per each animal. In 2 cases, 1 fetus was delivered and prior to sacrifice the fetal liver was sampled in toto (30 days of gestational age). These pregnancies were allowed to continue to term and were uneventful with a full-term spontaneous delivery of the remaining fetuses. In the other 6 pregnancies, after the hysterotomy, the fetal abdomen was entered through a right-sided longitudinal incision and the liver was partially resected by thermocauterization. Fetal abdomen was closed in 1 layer (non absorbable suture 7-0). The fetus was then returned in the uterus and, after amniotic fluid restoration with warmed saline, the hysterotomy was sutured in double layer (polyglycolic 5-0). Maternal abdomen was closed in 1 layer (polyglycolic 4-0) and the skin in a continuous overlying fashion (silk 3-0). The abdominal cavity of the 2 adult male rabbits was entered through a right subcostal incision. Partial liver resection was performed, and abdominal and skin closure followed the same techniques used for the pregnant does. The treated livers were then sampled in toto at 24, 48, 72 hrs and 4 days after surgery from the fetuses, and at 7 days from the adult rabbits. Histological stains were: H & E; Van Gieson; Masson; Alcian Bleu; PAS. Fetal histology showed a low inflammatory reaction poor in PMN cells with minimal deposition of collagen and a high amount of glycogen in the hepatocytes. The inflammatory response to resection was much more evident in the adult samples as much as the abundant intra and extra-cellular deposition of collagen associated to a minor amount of intracellular glycogen. The peculiar features of liver regeneration in the fetus, deserve further experimental studies.