Extracellular phosphorylation converts pigment epithelium-derived factor from a neurotrophic to an antiangiogenic factor

The pigment epithelium-derived factor (PEDF) belongs to the superfamily of serine protease inhibitors (serpin). There have been 2 distinct functions attributed to this factor, which can act either as a neurotrophic or as an antiangiogenic factor. Besides its localization in the eye, PEDF was recently reported to be present also in human plasma. We found that PEDF purified from plasma is a phosphoprotein, which is extracellularly phosphorylated by protein kinase CK2 (CK2) and to a lesser degree, intracellularly, by protein kinase A (PKA). CK2 phosphorylates PEDF on 2 main residues, Ser24 and Ser114, and PKA phosphorylates PEDF on one residue only, Ser227. The physiologic relevance of these phosphorylations was determined using phosphorylation site mutants. We found that both CK2 and PKA phosphorylations of PEDF markedly affect its physiologic function. The fully CK2 phosphorylation site mutant S24, 114E abolished PEDF neurotrophic activity but enhanced its antiangiogenic activity, while the PKA phosphorylation site mutant S227E reduced PEDF antiangiogenic activity. This is a novel role of extracellular phosphorylation that is shown here to completely change the nature of PEDF from a neutrophic to an antiangiogenic factor.     

Salmonella diskitis in a 2-year old immunocompetent child

Spine infections are uncommon in paediatrics and are generally caused by Staphylococcus aureus. Salmonella spp. are a rare cause of spine infections, usually affecting children with sickle-cell anaemia. We present a case of group C1 Salmonella diskitis in a previously healty 2-y-old child, and review the relevant literature.     

Prolonged fever of unknown origin and hemophagocytosis evolving into acute lymphoblastic leukemia

Hemophagocytic syndrome (HPS) is an unusual acute syndrome presenting with fever, hepatosplenomegaly, and cytopenias. The hallmark of HPS is the accumulation of activated macrophages that engulf hematopoietic cells in the reticuloendothelial system. Most cases of HPS in adults are secondary to infection or malignancy, and thus investigation of the underlying disease is necessary. We describe a patient with prolonged fever, HPS, and chromosomal abnormalities in the bone marrow who underwent thorough evaluation for the cause of his symptoms. A final diagnosis of acute lymphoblastic leukemia (ALL) was established in a fourth, repeated bone marrow biopsy performed more than 2 months after the first presenting symptom appeared. This unusual case demonstrates the importance of cytogenetic abnormalities found in cases of HPS and the importance of repeated testing when an underlying disease is suspected.     

Atomic structure and hierarchical assembly of a cross-β amyloid fibril

The cross-β amyloid form of peptides and proteins represents an archetypal and widely accessible structure consisting of ordered arrays of β-sheet filaments. These complex aggregates have remarkable chemical and physical properties, and the conversion of normally soluble functional forms of proteins into amyloid structures is linked to many debilitating human diseases, including several common forms of age-related dementia. Despite their importance, however, cross-β amyloid fibrils have proved to be recalcitrant to detailed structural analysis. By combining structural constraints from a series of experimental techniques spanning five orders of magnitude in length scale—including magic angle spinning nuclear magnetic resonance spectroscopy, X-ray fiber diffraction, cryoelectron microscopy, scanning transmission electron microscopy, and atomic force microscopy—we report the atomic-resolution (0.5 Å) structures of three amyloid polymorphs formed by an 11-residue peptide. These structures reveal the details of the packing interactions by which the constituent β-strands are assembled hierarchically into protofilaments, filaments, and mature fibrils.It is well established that a wide variety of peptides or proteins without any evident sequence similarity can self-assemble into amyloid fibrils (1, 2). These structures have many common characteristics, typically being 100–200 Å in diameter and containing a universal “cross-β” core structure composed of arrays of β-sheets running parallel to the long axis of the fibrils (3). These fibrillar states are highly ordered, with persistence lengths of the order of microns (4) and mechanical properties comparable to those of steel and dragline silk, and much greater than those typical of biological filaments such as actin and microtubules (5). Amyloid fibrils can also possess very high kinetic and thermodynamic stabilities, often exceeding those of the functional folded states of proteins (6), as well as a greater resistance to degradation by chemical or biological means (7). Several functional forms of proteins that exploit these properties have been observed in biological systems (8). More generally, however, the conversion of normally soluble functional proteins into the amyloid state is associated with many debilitating human disorders, ranging from Alzheimer’s disease to type II diabetes (1, 9). Our understanding of the nature of this type of filamentous aggregate has greatly improved in recent years (3, 10–19), particularly through the structural determination of their elementary β-strand building blocks (20) and the characterization of their assembly into cross-β steric zippers (21, 22). However, a thorough understanding of the hierarchical assembly of these individual structural elements into fully-formed fibrils, which display polymorphism but possess a range of generic features (23), has so far been limited by the absence of a complete atomic-resolution cross-β amyloid structures (2).We report here the simultaneous determination of the atomic-resolution structures of a cross-β amyloid fibril and two polymorphic variants, formed by an 11-residue fragment of the protein transthyretin, TTR(105–115) (20). These fibrils have the classic amyloid morphology, being 100–200 Å in diameter and typically 1–3 µm in length (SI Appendix, Fig. S1). We have achieved this objective by bringing together a set of complementary biophysical techniques to provide atomic structures of these complex aggregates. Specifically, we have combined interatomic structural restraints from magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy with high-resolution electron density maps from cryoelectron microscopy (cryo-EM), together with data from X-ray fiber diffraction, scanning transmission electron microscopy (STEM), and atomic force microscopy (AFM) measurements. Our results reveal the molecular basis of the stability and polymorphism of these amyloid fibrils by defining at high resolution the variety of structural elements in their hierarchical self-assembly.     

The Sheba Medical Center healthcare workers' children's school: can we open schools safely?

ObjectiveThe role of school closure in mitigating coronavirus disease 2019 (COVID-19) transmission has been questioned. In our medical centre, during a 9-week national lockdown, an alternative school was opened for health-care workers' (HCW) children with a small number of children per class and strict symptom surveillance. After lockdown was lifted we screened children and their parents for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology.MethodsWe conducted a cross-sectional study of HCW parents and their children after one teacher contracted COVID-19 following exposure at home and 53 children were exposed, isolated and tested by RT-PCR. We compared families with children attending the alternative school with families whose children who remained at home during the 9-week lockdown. Epidemiological and medical data were collected using a short questionnaire; nasopharyngeal and oropharyngeal swabs were obtained and tested for SARS-CoV-2 by RT-PCR, and blood was collected for SARS-CoV-2 IgA and IgG titres.ResultsA total of 435 children attended the Sheba alternative school. Among the 53 children exposed to the infected teacher, none tested positive by RT-PCR. Of these, 18 children–parent pairs were tested for serology and all were negative. A total of 106/435 (24%) children and their 78 parents were recruited for the cross-sectional study; 70 attended the Sheba school and 36 did not. Approximately 16% of children in either group reported symptoms (11/70 in the school group and 6/36 in the ‘stay home’ group), but SARS-CoV-2 was not detected by PCR in any, and previous exposure, as determined by serological tests, was low and not significantly different between the groups.ConclusionIn an alternative school for children of HCWs, active during COVID-19 national outbreak, we found no evidence of increased infection compared with children that stayed home.     

Hematuria as the presenting symptom of a metastatic thyroid cancer

A 67-year-old man is presented who was admitted to our hospital for the onset of hematuria and acute urinary retention and who was found to have a 10-cm solid mass in the right obturator fossa compressing the bladder wall. Histology revealed the presence of a distant metastases from thyroid cancer. To the best of our knowledge, this is the first case of a thyroid cancer presenting with hematuria and acute urinary retention caused by distant metastases to intrapelvic soft tissue.     

"What" precedes "which": developmental neural tuning in face- and place-related cortex

Although category-specific activation for faces in the ventral visual pathway appears adult-like in adolescence, recognition abilities for individual faces are still immature. We investigated how the ability to represent "individual" faces and houses develops at the neural level. Category-selective regions of interest (ROIs) for faces in the fusiform gyrus (FG) and for places in the parahippocampal place area (PPA) were identified individually in children, adolescents, and adults. Then, using an functional magnetic resonance imaging adaptation paradigm, we measured category selectivity and individual-level adaptation for faces and houses in each ROI. Only adults exhibited both category selectivity and individual-level adaptation bilaterally for faces in the FG and for houses in the PPA. Adolescents showed category selectivity bilaterally for faces in the FG and houses in the PPA. Despite this profile of category selectivity, adolescents only exhibited individual-level adaptation for houses bilaterally in the PPA and for faces in the "left" FG. Children only showed category-selective responses for houses in the PPA, and they failed to exhibit category-selective responses for faces in the FG and individual-level adaptation effects anywhere in the brain. These results indicate that category-level neural tuning develops prior to individual-level neural tuning and that face-related cortex is disproportionately slower in this developmental transition than is place-related cortex.     

Platelet adhesion defect in type I Gaucher Disease is associated with a risk of mucosal bleeding

Patients with type I Gaucher Disease (GD) may have a clinically significant bleeding tendency that is disproportionate to their platelet count. We hypothesized that impaired platelet adhesion might contribute to bleeding tendency. Adult patients with type I GD with platelet counts ≥130×10(9) /l and haematocrit ≥30% (n=48), obligatory carriers (n=52), and healthy controls (n=19) were studied. Platelet adhesion, using the IMPACT-R (Cone and Plate(let) Analyser), and platelet aggregation were determined. Type I GD patients had significantly lower platelet adhesion [surface coverage %, median (interquartile range)] 4·6 (3·2-7·5), compared to controls, 8·7 (7·6-10·3), or carriers, 8·1 (6·5-9·4; P=0·001). Platelet adhesion was not affected by the use of disease-specific enzyme replacement therapy but was improved in patients after splenectomy, 7·2 (5·8-9·3). Mixing tests showed that the reduced adhesion was an intrinsic platelet defect. Mucosal bleeding was reported in 17 (35·4%) patients and was associated with abnormal adhesion [P=0·037, with an Odds Ratio (95% confidence interval) of 5·73 (1·1-29·6)]. Five patients (22%) had reduced platelet aggregation, all of whom had reduced platelet adhesion. Platelet aggregation defect was not associated with mucosal bleeding. In conclusion, platelet adhesion defect is a major thrombocytopathy in type I GD patients and can explain part of the increased tendency to bleeding.     

Structural imaging reveals anatomical alterations in inferotemporal cortex in congenital prosopagnosia

Congenital prosopagnosia (CP) refers to the lifelong impairment in face recognition in individuals who have intact low-level visual processing, normal cognitive abilities, and no known neurological disorder. Although the face recognition impairment is profound and debilitating, its neural basis remains elusive. To investigate this, we conducted detailed morphometric and volumetric analyses of the occipitotemporal (OT) cortex in a group of CP individuals and matched control subjects using high-spatial resolution magnetic resonance imaging. Although there were no significant group differences in the depth or deviation from the midline of the OT or collateral sulci, the CP individuals evince a larger anterior and posterior middle temporal gyrus and a significantly smaller anterior fusiform (aF) gyrus. Interestingly, this volumetric reduction in the aF gyrus is correlated with the behavioral decrement in face recognition. These findings implicate a specific cortical structure as the neural basis of CP and, in light of the familial history of CP, target the aF gyrus as a potential site for further, focused genetic investigation.