Brachial plexus neuritis in the context of acute HIV seroconversion illness: a case report

We report an unusual case of bilateral brachial plexus neuritis occurring during the seroconversion stage of an HIV infection in a 45-year-old man. Brachial plexus neuritis is thought to be an immune mediated inflammatory reaction resulting in acute onset of shoulder pain followed by muscle weakness and wasting. There is often a history of viral illness, diagnosis is clinical, and treatment is supportive. Many sufferers are left with residual defects. Clinicians should consider the possibility of HIV infection when managing a patient with brachial plexus neuritis.     

Moiréless correlations in ABCA graphene

Atomically thin van der Waals materials stacked with an interlayer twist have proven to be an excellent platform toward achieving gate-tunable correlated phenomena linked to the formation of flat electronic bands. In this work we demonstrate the formation of emergent correlated phases in multilayer rhombohedral graphene––a simple material that also exhibits a flat electronic band edge but without the need of having a moiré superlattice induced by twisted van der Waals layers. We show that two layers of bilayer graphene that are twisted by an arbitrary tiny angle host large (micrometer-scale) regions of uniform rhombohedral four-layer (ABCA) graphene that can be independently studied. Scanning tunneling spectroscopy reveals that ABCA graphene hosts an unprecedentedly sharp van Hove singularity of 3–5-meV half-width. We demonstrate that when this van Hove singularity straddles the Fermi level, a correlated many-body gap emerges with peak-to-peak value of 9.5 meV at charge neutrality. Mean-field theoretical calculations for model with short-ranged interactions indicate that two primary candidates for the appearance of this broken symmetry state are a charge-transfer excitonic insulator and a ferrimagnet. Finally, we show that ABCA graphene hosts surface topological helical edge states at natural interfaces with ABAB graphene which can be turned on and off with gate voltage, implying that small-angle twisted double-bilayer graphene is an ideal programmable topological quantum material.

Two-dimensional (2D) van der Waals heterostructures with an interlayer twist have provided a new avenue for observing emergent tunable many-body electron phenomena. Recent experimental realizations include twisted bilayer graphene (tBG) near the so-called “magic angle” of 1.1° (1–3), twisted double-bilayer graphene (tDBG) (4–6), ABC trilayer graphene on near-perfectly aligned hexagonal boron nitride (hBN) (ABC-tLG/hBN) (7, 8) and transition-metal dichalcogenide heterostructures (9–12) [with predictions on a variety of other systems (13, 14)]. All of these systems host an interplay of two phenomena––the presence of one or more van Hove singularities (which we colloquially refer to as “flat bands” henceforth) at low energy where the density of states is sharply peaked, and the existence of a moiré pattern that creates a unit cell that is about a hundred times larger than the carbon–carbon nearest-neighbor distance in graphene. The large number of electrons with quenched kinetic energy make the flat bands conducive to interaction-driven phases (15). The enlarged moiré unit cell is thought to reduce both the flat-band bandwidth and the interaction energy scales, and also introduces easily accessible integer fillings that create Mott-like insulating states (1–12), the relation of which to nearby superconductivity is debated. A natural question that arises from all of these works is whether the moiré pattern is a necessary condition for the observation of correlated many-body phases, or whether it is simply sufficient to further reduce the flat-band bandwidth and hence the kinetic energy in the heterostructure.In this regard, multilayer rhombohedral (ABC) graphene offers a different perspective toward achieving a flat-band edge without the use of a moiré potential (16). Indeed, in a seminal work (17), it was theoretically shown that the low-energy band structure of multilayer rhombohedral graphene has a sharply peaked density of state (DOS), with the band structure E(k)∝kN (where N is the number of layers) at low energy in the nearest-neighbor hopping approximation. This implies a peak in the DOS at charge neutrality in this material for N>2, with an appreciable fraction of the entire band within this peak (18). Indeed, this physics is already at play in ABC-tLG/hBN (7, 8), where some of the flatness of the bands comes from the intrinsic band structure of ABC graphene, which is then further flattened and isolated by the moiré pattern from the hBN alignment. A facile alternative to flatten the bandwidth without introducing a moiré potential is to simply increase the number of layers of the rhombohedral stacked graphene. Unfortunately, isolating rhombohedral stacked graphene of any thickness is extremely difficult as it is less energetically favorable than the multilayer counterpart, Bernal stacked graphene. Since the difference between rhombohedral and Bernal graphene is simply a lattice shift, and the interlayer van der Waals forces are weak, it is well known that rhombohedral graphene reverts to the Bernal form when samples are processed with heat, pressure, or while performing lithography (19). In this work, we show that twisting two sheets of tDBG by a tiny (<0.1°) angle is a simple and robust method to create large area (up to micrometer-scale) rhombohedral graphene of four-layer thickness (ABCA graphene). We present gate-tunable scanning tunneling microscopy and spectroscopy (STM/STS) measurements at 5.7 K on these regions. We show that correlated phases can be achieved without the need for a moiré pattern and that rhombohedral graphene has unique topological properties.     

Immunization with genetically attenuated P. falciparum parasites induces long-lived antibodies that efficiently block hepatocyte invasion by sporozoites

Whole-parasite malaria vaccines have shown promise in clinical trials. We recently reported the first human trial of a malaria vaccine based on Plasmodium falciparum genetically attenuated parasites (PfGAP). Herein we report for the first time that PfGAP induces prolonged functional humoral responses in humans. Six volunteers were exposed to 5 bites of PfGAP-infected mosquitoes followed by approximately 200 bites. Plasma collected from all volunteers 3 months after the last exposure efficiently inhibits invasion of hepatocytes by P. falciparum sporozoites. The level of inhibition observed is comparable to that attained using plasma collected after 4–5 intravenously administrations of high numbers of irradiated sporozoites, validating the potential of PfGAP malaria vaccines. Our data highlight the role of antibody responses in pre-erythrocytic stages of human malaria, and suggests that to be protective, malaria vaccines might need to elicit long-lasting functional antibodies in addition to cellular responses.     

A novel treatment for chronic pancreatitis

Background Hereditary pancreatitis is an important cause of chronic pancreatitis, which may result in endocrine and exocrine failure. This may necessitate simultaneous pancreas and kidney transplant (SPK). Bladder drainage of the exocrine secretions may cause problems. Aim To report one such case and its surgical correction. Methods A 20-year-old male with insulin-dependent diabetes mellitus secondary to idiopathic chronic pancreatitis had a SPK with bladder drainage. Urological and metabolic complications secondary to the drainage of pancreatic secretions, rich in proteolytic enzymes required convertion from bladder to enteric drainage. Results He was able to discontinue his pancreatic enzyme supplements, ceased to have steatorrhoea and gained weight. He was referred to the €pean Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (€PAC), hereditary pancreatitis was confirmed by genetic analysis. Conclusion Enteric-drained pancreas transplantation is a successful treatment for exocrine as well as endocrine pancreatic failure and should be considered as a treatment option in patients with chronic pancreatitis.     

Children's Primary Health Care Services: A Social-Cognitive Model of Sustained High Use

Significant percentages of children exhibit patterns of sustained high use of primary health care services. Unfortunately, current models fail to explain the processes that drive and maintain such patterns. We draw upon the pediatric utilization and social-cognitive literature to develop a model that explains the mechanisms that ultimately drive and maintain patterns of prolonged high use. Specifically, we propose that parental stress and low self-efficacy for coping with various parenting and life demands interact to drive the utilization of pediatric services. We outlined sequelae of frequent physician that serve to maintain high use. This model suggests a number of psychological interventions that clinical health psychologists might undertake to remediate inappropriate, sustained high use of children's primary healthcare services.