How do we differentiate not demonise - Is there a role for healthier processed foods in an age of food insecurity? Proceedings of a roundtable event

The 'ultra-processed food' (UPF) concept, with classification of foods by 'level of processing' rather than nutrient profiles, and its relationship with health outcomes, is currently a topic of debate among academics and increasingly referred to in the media. The British Nutrition Foundation convened a virtual roundtable on 6th July 2022 to gather views on the use of the term (and current definitions of) UPF for public health messaging, seeking to establish areas of consensus and disagreement and identify topics for further research. A small group of invited expert stakeholders attended, including representatives from academia, policy, behavioural science, communications, health, food science, retail and consumer interests. Participants' discussions clustered into cogent themes which included: problems with the use of definitions for UPF, the lack of causal evidence and defined mechanisms linking processing per se with poor health outcomes, and advice that may result in consumer confusion. There was agreement that many foods classified as UPF are high in fat, sugars and/or salt and public health messages should continue to focus on reducing these in the diet since it is unclear whether reported associations between high intakes of UPF and poor health reflect poorer dietary patterns (defined by nutrient intakes), and nutrient-health relationships are well established. Examples of misalignment were also highlighted (i.e. some foods are classified as UPF yet recommended in food-based dietary guidelines [featuring in healthy dietary patterns]). This raises challenges for consumer communication around UPF. Concern was also expressed about potential unintended consequences, particularly for vulnerable groups, where advice to avoid UPF could create stigma and guilt due to lack of time or facilities to prepare and cook meals from scratch. It could also impact on nutrient intakes, as some foods classified as UPF represent more affordable sources of important nutrients (e.g. packaged wholemeal bread). Discordance between the concept of UPF and current strategies to improve public health, such as reformulation, was also discussed. The group concluded that the use of the concept of UPF in UK policy (e.g. dietary guidelines) would be unhelpful at present. Overall, participants felt that it was more important to focus on providing practical advice around selection of healthier processed foods and making healthier foods more accessible rather than promoting the avoidance of UPF. The latter may act to demonise all foods classified as UPF by current definitions, including some affordable nutrient-dense foods.

Constitutional mismatch repair-deficiency and whole-exome sequencing as the means of the rapid detection of the causative MSH6 defect

BACKGROUND

Cases of children with more than one type of cancer either diagnosed simultaneously or successively, rarely occur in pediatric oncology. A second malignant neoplasm may be caused by mutagenic effects of the treatment of the primary malignancy and/or may point towards an underlying genetic cancer susceptibility syndrome. One example of such a syndrome is constitutional mismatch repair-deficiency, (CMMR-D) which carries an increased risk of various tumors including childhood hematologic malignancies and Lynch syndrome associated tumors. Timely diagnosis of CMMR-D is crucial, since this diagnosis has implications for the entire family.

PATIENT

We report the case of a 15-year-old girl who was born to consanguineous parents. At the age of 20 months she was diagnosed with a T-cell non-Hodgkin lymphoma. Treatment was given according to NHL-BFM 95. 12 years later, an invasive adenocarcinoma of the colon was surgically removed which relapsed shortly afterwards.

METHODS

Whole-exome sequencing of germline DNA was employed to rapidly detect the underlying mutation in this suspected CMMR-D patient.

RESULTS

After a short turnaround time of less than 3 weeks, the diagnosis of CMMR-D could be confirmed by the identification of a homozygous 29-bp deletion in MSH6 (exon 6), which was confirmed by independent methods.

CONCLUSIONS

We demonstrate that "bed-side" whole-exome sequencing is both feasible and cost-effective and may be the method of choice to rapidly uncover the genetical basis of (inherited) diseases.

Magnetism in single metalloorganic complexes formed by atom manipulation

The magnetic properties of molecular structures can be tailored by chemical synthesis or bottom-up assembly at the atomic scale. We used scanning tunneling microscopy to study charge and spin transfer in individual complexes of transition metals with the charge acceptor, tetracyanoethylene (TCNE). The complexes were formed on a thin insulator, Cu2N on Cu(100), by manipulation of individual atoms and molecules. The Cu2N layer decouples the complexes from Cu electron density, enabling direct imaging of the TCNE molecular orbitals as well as spin-flip inelastic electron tunneling spectroscopy. Results were obtained at low temperature down to 1 K and in magnetic fields up to 7 T in order to resolve splitting of spin states in the complexes. We also performed spin-polarized density functional theory calculations to compare with the experimental data. Our results indicate that charge transfer to TCNE leads to a change in spin magnitude, Kondo resonance, and magnetic anisotropy for the metal atoms.

Development and validation of the disease-specific Short Bowel Syndrome-Quality of Life (SBS-QoL™) scale

BACKGROUND & AIMS

Subjects with short bowel syndrome (SBS) have impaired quality of life (QoL). No disease-specific instrument has been available to measure treatment-induced changes in QoL over time. Therefore, the aim was to develop and validate an SBS-specific QoL scale.

METHODS

Classical test theory and Food and Drug Administration (FDA) guidance were applied for development and validation of the SBS-QoL™. Procedures included item generation and raw scale construction. Factor analysis, construct validity and internal consistency were assessed in a non-interventional observation, test re-test reliability and responsiveness in a randomised clinical study.

RESULTS

The SBS-QoL™ comprises 17 items including two subscales. Subjects assessed the scale as easy to handle and comprehensible. Good construct validity was shown by comparison with the Home Parenteral Nutrition-Quality Of Life questionnaire as an external scale, which yielded moderately high correlation (r ≥ 0.7). High internal consistency was demonstrated (Cronbach's alpha: 0.94). Also the test re-test reliability was high (r ≥ 0.95), indicating reliable reproducibility of results. The Responsiveness Index (1.84) indicated the ability of the scale to detect changes in QoL over time.

CONCLUSIONS

The SBS-QoL™ is an easy to handle and comprehensible SBS-specific subject-reported QoL scale. It is valid, reliable and sensitive with excellent psychometric characteristics to measure treatment-induced changes in QoL over time in subjects with SBS.

Bistable charge configuration of donor systems near the GaAs(110) surfaces

In gated semiconductor devices, the space charge layer that is located under the gate electrode acts as the functional element. With increasing gate voltage, the microscopic process forming this space charge layer involves the subsequent ionization or electron capture of individual dopants within the semiconductor. In this Letter, a scanning tunneling microscope tip is used as a movable gate above the (110) surface of n-doped GaAs. We study the build-up process of the space charge region considering donors and visualize the charge states of individual and multi donor systems. The charge configuration of single donors is determined by the position of the tip and the applied gate voltage. In contrast, a two donor system with interdonor distances smaller than 10 nm shows a more complex behavior. The electrostatic interaction between the donors in combination with the modification of their electronic properties close to the surface results in ionization gaps and bistable charge switching behavior.

Spin excitations of a Kondo-screened atom coupled to a second magnetic atom

Screening the electron spin of a magnetic atom via spin coupling to conduction electrons results in a strong resonant peak in the density of states at the Fermi energy, the Kondo resonance. We show that magnetic coupling of a Kondo atom to another unscreened magnetic atom can split the Kondo resonance into two peaks. Inelastic spin excitation spectroscopy with scanning tunneling microscopy is used to probe the Kondo effect of a Co atom, supported on a thin insulating layer on a Cu substrate, that is weakly coupled to a nearby Fe atom to form an inhomogeneous dimer. The Kondo peak is split by interaction with the non-Kondo atom, but can be reconstituted with a magnetic field of suitable magnitude and direction. Quantitative modeling shows that this magnetic field results in a spin-level degeneracy in the dimer, which enables the Kondo effect to occur.

Enhanced donor binding energy close to a semiconductor surface

We measured the ionization threshold voltage of individual impurities close to a semiconductor-vacuum interface, where we use the STM tip to ionize individual donors. We observe a reversed order of ionization with depth below the surface, which proves that the binding energy is enhanced towards the surface. This is in contrast to the predicted reduction for a Coulombic impurity in the effective mass approach. We can estimate the binding energy from the ionization threshold and show experimentally that in the case of silicon doped gallium arsenide the binding energy gradually increases over the last 1.2 nm below the (110) surface.

Controlled charge switching on a single donor with a scanning tunneling microscope

The charge state of individually addressable impurities in semiconductor material was manipulated with a scanning tunneling microscope. The manipulation was fully controlled by the position of the tip and the voltage applied between tip and sample. The experiments were performed at low temperature on the (110) surface of silicon doped GaAs. Silicon donors up to 1 nm below the surface can be reversibly switched between their neutral and ionized state by the local potential induced by the tip. By using ultrasharp tips, the switching process occurs close enough to the impurity to be observed as a sharp circular feature surrounding the donor. By utilizing the controlled manipulation, we were able to map the Coulomb potential of a single donor at the semiconductor-vacuum interface.

Probing semiconductor gap states with resonant tunneling

Tunneling transport through the depletion layer under a GaAs {110} surface is studied with a low temperature scanning tunneling microscope (STM). The observed negative differential conductivity is due to a resonant enhancement of the tunneling probability through the depletion layer mediated by individual shallow acceptors. The STM experiment probes, for appropriate bias voltages, evanescent states in the GaAs band gap. Energetically and spatially resolved spectra show that the pronounced anisotropic contrast pattern of shallow acceptors occurs exclusively for this specific transport channel. Our findings suggest that the complex band structure causes the observed anisotropies connected with the zinc blende symmetry.