The partially asymmetric zero range process with quenched disorder

We consider the one-dimensional partially asymmetric zero range process where the hopping rates as well as the easy direction of hopping are random variables. For this type of disorder there is a condensation phenomena in the thermodynamic limit: the particles typically occupy one single site and the fraction of particles outside the condensate is vanishing. We use extreme value statistics and an asymptotically exact strong disorder renormalization group method to explore the properties of the steady state. In a finite system of $L$ sites the current vanishes as $J \sim L^{-z}$, where the dynamical exponent, $z$, is exactly calculated. For $0<z<1$ the transport is realized by $N_a \sim L^{1-z}$ active particles, which move with a constant velocity, whereas for $z>1$ the transport is due to the anomalous diffusion of a single Brownian particle. Inactive particles are localized at a second special site and their number in rare realizations is macroscopic. The average density profile of inactive particles has a width of, $\xi \sim \delta^{-2}$, in terms of the asymmetry parameter, $\delta$. In addition to this, we have investigated the approach to the steady state of the system through a coarsening process and found that the size of the condensate grows as $n_L \sim t^{1/(1+z)}$ for large times. For the unbiased model $z$ is formally infinite and the coarsening is logarithmically slow.Comment: 12 pages, 9 figure

ATPγS stalls splicing after B complex formation but prior to spliceosome activation.

The ATP analog ATPγS inhibits pre-mRNA splicing in vitro, but there have been conflicting reports as to which step of splicing is inhibited by this small molecule and its inhibitory mechanism remains unclear. Here we have dissected the effect of ATPγS on pre-mRNA splicing in vitro. Addition of ATPγS to splicing extracts depleted of ATP inhibited both catalytic steps of splicing. At ATPγS concentrations ≥0.5 mM, precatalytic B complexes accumulate, demonstrating a block prior to or during the spliceosome activation stage. Affinity purification of the ATPγS-stalled B complexes (B(ATPγS)) and subsequent characterization of their abundant protein components by 2D gel electrophoresis revealed that B(ATPγS) complexes are compositionally more homogeneous than B complexes previously isolated in the presence of ATP. In particular, they contain little or no Prp19/CDC5L complex proteins, indicating that these proteins are recruited after assembly of the precatalytic spliceosome. Under the electron microscope, B(ATPγS) complexes exhibit a morphology highly similar to B complexes, indicating that the ATPγS-induced block in the transformation of the B to B(act) complex is not due to a major structural defect. Likely mechanisms whereby ATPγS blocks spliceosome assembly at the activation stage, including inhibition of the RNA helicase Brr2, are discussed. Given their more homogeneous composition, B complexes stalled by ATPγS may prove highly useful for both functional and structural analyses of the precatalytic spliceosome and its conversion into an activated B(act) spliceosomal complex

Body mass index at diagnosis of a childhood brain tumor; a reflection of hypothalamic-pituitary dysfunction or lifestyle?

Purpose: Childhood brain tumor survivors (CBTS) are at risk of becoming overweight, which has been shown to be associated with hypothalamic-pituitary (HP) dysfunction during follow-up. Body mass index (BMI) at diagnosis is related to BMI at follow-up. It is uncertain, however, whether aberrant BMI at brain tumor diagnosis reflects early hypothalamic dysfunction or rather reflects genetic and sociodemographic characteristics. We aimed to examine whether BMI at childhood brain tumor diagnosis is associated with HP dysfunction at diagnosis or its development during follow-up. Methods: The association of BMI at diagnosis of a childhood brain tumor to HP dysfunction at diagnosis or during follow-up was examined in a Dutch cohort of 685 CBTS, excluding children with craniopharyngioma or a pituitary tumor. Individual patient data were retrospectively extracted from patient charts. Results: Of 685 CTBS, 4.7% were underweight, 14.2% were overweight, and 3.8% were obese at diagnosis. Being overweight or obese at diagnosis was not associated with anterior pituitary deficiency or diabetes insipidus at diagnosis or during follow-up. In children with suprasellar tumors, being obese at diagnosis was associated with central precocious puberty. Conclusion: Overweight or obesity at diagnosis of a childhood brain tumor seems not to be associated with pituitary deficiencies. These results suggest that genetics and lifestyle may be more important etiologic factors for higher BMI at diagnosis in these children than hypothalamic dysfunction. To improve the long-term outcome of CBTS with regards to overweight and obesity, more attention should be given to lifestyle already at the time of brain tumor treatment

Recommendations on Surveillance for Differentiated Thyroid Carcinoma in Children with PTEN Hamartoma Tumor Syndrome

BACKGROUND: PTEN hamartoma tumor syndrome (PHTS) represents a group of syndromes caused by a mutation in the PTEN gene. Children with a germline PTEN mutation have an increased risk of developing differentiated thyroid carcinoma (DTC). Several guidelines have focused on thyroid surveillance in these children, but studies substantiating these recommendations are lacking. OBJECTIVE: The present study intends to provide the available evidence for a thyroid carcinoma surveillance program in children with PHTS. METHODS: An extensive literature search was performed to identify all studies on DTC in pediatric PHTS patients. Two pediatric cases are presented to illustrate the pros and cons of thyroid carcinoma surveillance. Recommendations for other patient groups at risk for DTC were evaluated. Consensus within the study team on recommendations for children with PHTS was reached by balancing the incidence and behavior of DTC with the pros and cons of thyroid surveillance, and the different surveillance methods. RESULTS: In 5 cohort studies the incidence of DTC in childhood ranged from 4 to 12%. In total 57 cases of DTC and/or benign nodular disease in pediatric PHTS patients were identified, of which 27 had proven DTC, with a median age of 12 years (range 4-17). Follicular thyroid carcinoma (FTC) was diagnosed in 52% of the pediatric DTC patients. No evidence was found for a different clinical behavior of DTC in PHTS patients compared to sporadic DTC. CONCLUSIONS: Children with PHTS are at increased risk for developing DTC, with 4 years being the youngest age reported at presentation and FTC being overrepresented. DTC in pediatric PHTS patients does not seem to be more aggressive than sporadic DTC. RECOMMENDATIONS: Surveillance for DTC in pediatric PHTS patients seems justified, as early diagnosis may decrease morbidity. Consensus within the study team was reached to recommend surveillance from the age of 10 years onwards, since at that age the incidence of DTC seems to reach 5%. Surveillance for DTC should consist of yearly neck palpation and triennial thyroid ultrasound. Surveillance in children with PHTS should be performed in a center of excellence for pediatric thyroid disease or PHTS

Acquired hypothalamic dysfunction in childhood: ‘what do patients need?’ – an Endo-ERN survey

Objective: Hypothalamic dysfunction is a rare condition and can be encountered in patients who have been diagnosed or treated for a suprasellar brain tumor. Due to its rarity, the signs and symptoms of hypothalamic dysfunction may be difficult to recognize, leading to delayed diagnosis of the suprasellar brai n tumor or to difficulties in finding the health-care expertise for hypothalamic dysfunctio n after tumor treatment. To improve the care and outcome of patients with acquired hypothalamic dysfunction, professionals are required to understand the patient’s needs. Design: A worldwide online survey was distributed from April 2022 to October 2022 to patients with childhood-onset hypothalamic dysfunction (as reported by the patient) following a brain tumor. Methods: Patients were notified about the survey through patient advocacy groups, the SIOPe craniopharyngioma working group and the Endo-ERN platform. Results: In total, 353 patients with hypothalamic dysfunction following craniopharyngioma (82.2%), low-grade glioma (3.1%) or a pituitary tumor (8.2%) or caregivers responded to the survey. Sixty-two percent had panhypopituitarism. Obesity (50.7%) and fatigue (48.2%) were considered the most important health problems. Unmet needs were reported for help with diet, exercise and psychosocial issues. Patients’ suggestions for future research include new treatments for hypothalamic obesity and alternative ways for hormone administration. Conclusions: According to the patient’s perspective, care for acquired hypothalamic dysfunction can be improved if delivered by experts with a holistic view of the patient in a multidisciplinary setting with a focus on quality of life. Future care and research on hypothalamic dysfunction must integrate the patients’ unmet needs. Significance statement: Patients with hypothalamic dysfunction may experience a variety of symptoms, which are not always adequately recognized or addressed. In previous papers, the perspective of caregivers of children with craniopharyngioma has been reported (Klages et al. 2022, Craven et al. 2022). Now we address the patients’ perspective on acquired hypothalamic dysfunction using an Endo-ERN global survey. According to the patients’ perspective, care can be improved, with needs for improvement in the domains of obesity, fatigue and lifestyle. Research may focus on ways to improve hypothalamic obesity and alternative ways for hormone administration. Ideally, care should be delivered by doctors who have a holistic view of the patient in a multidisciplinary expert team. The results of this study can be used to formulate best practices for clinical care and to design future research proposals