A Study of Neutral Meson Production in Hadronic Interactions

This thesis covers the work of the author as a postgraduate student at the University of Glasgow, between October 1982 and September 1985. The experiment WA70 was designed to study the production of high transverse momentum direct photons in hadron-hadron interactions. The experiment took place at the CERN laboratory in Switzerland. The apparatus used was the OMEGA spectrometer facility, and a purpose built electromagnetic calorimeter. Data was taken with a hadron beam, at an energy of 280 GeV, incident on a liquid hydrogen target. The beam composition could be selected to be either negative pions, or unseparated protons and positive pions. One of the principal features of the calorimeter was its source calibration system. Sixteen radioactive sources could be positioned within the calorimeter to provide calibration data. Much of the author's work in the early stages of the experiment was on setting up and understanding the calibration system, and on applying the results to the experiment. The work done, and the results obtained, are presented here. One of the requirements of an experiment studying direct photon physics is the ability to accurately identify background sources of photons. The main source of such background is the decay of high transverse momentum pi s, and to a lesser extent, ns. The study of the production of pi s and ns is therefore important to the experiment. The latter part of this thesis presents the work of the author on the study of these mesons. The aim of the analysis is to derive the cross sections for the production of high transverse momentum pi and n mesons. The method of analysis and the results are presented

Reply: “comment on: The vitamin D–folate hypothesis as an evolutionary model for skin pigmentation: An update and integration of current ideas, nutrients 2018, 10, 554”

We thank Elias and Williams for their interest in our review [...

The vitamin D–folate hypothesis as an evolutionary model for skin pigmentation: An update and integration of current ideas

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. Vitamin D is unique in being generated in our skin following ultraviolet radiation (UVR) exposure. Ongoing research into vitamin D must therefore always consider the influence of UVR on vitamin D processes. The close relationship between vitamin D and UVR forms the basis of the “vitamin D–folate hypothesis”, a popular theory for why human skin colour has evolved as an apparent adaption to UVR environments. Vitamin D and folate have disparate sensitivities to UVR; whilst vitamin D may be synthesised following UVR exposure, folate may be degraded. The vitamin D–folate hypothesis proposes that skin pigmentation has evolved as a balancing mechanism, maintaining levels of these vitamins. There are several alternative theories that counter the vitamin D–folate hypothesis. However, there is significant overlap between these theories and the now known actions of vitamin D and folate in the skin. The focus of this review is to present an update on the vitamin D–folate hypothesis by integrating these current theories and discussing new evidence that supports associations between vitamin D and folate genetics, UVR, and skin pigmentation. In light of recent human migrations and seasonality in disease, the need for ongoing research into potential UVR-responsive processes within the body is also discussed

Environmental UVR Levels and Skin Pigmentation Gene Variants Associated with Folate and Homocysteine Levels in an Elderly Cohort

Ultraviolet radiation (UVR) is a ubiquitous exposure which may contribute to decreased folate levels. Skin pigmentation mediates the biological effect of UVR exposure, but its relationship to folate levels is unexamined. Interactions may exist between UVR and pigmentation genes in determining folate status, which may, in turn, impact homocysteine levels, a potential risk factor for multiple chronic diseases. Therefore, independent and interactive influences of environmental UVR and genetic variants related to skin pigmentation (MC1R-rs1805007, IRF4-rs12203592 and HERC2-rs12913832) on folate (red blood cell (RBC) and serum) and homocysteine levels were examined in an elderly Australian cohort (n = 599). Genotypes were assessed by RT/RFLP-PCR, and UVR exposures were assessed as the accumulated erythemal dose rate accumulated over 4 months (4M-EDR). Multivariate analysis found significant negative associations between 4M-EDR and RBC folate (p < 0.001, β = -0.19), serum folate (p = 0.045, β = -0.08) and homocysteine levels (p < 0.001, β = -0.28). Significant associations between MC1R-rs1805007 and serum folate levels (p = 0.020), and IRF4-rs12203592 and homocysteine levels (p = 0.026) occurred but did not remain significant following corrections with confounders. No interactions between 4M-EDR and pigmentation variants in predicting folate/homocysteine levels were found. UVR levels and skin pigmentation-related variants are potential determinants of folate and homocysteine status, although, associations are mixed and complex, with further studies warranted

Interactions between bitter taste, diet and dysbiosis: Consequences for appetite and obesity

The type 2 family of taste receptors (T2Rs) detect and respond to bitter tastants. These receptors are expressed throughout the gastrointestinal (GI) tract, with location dependant roles. In the oral cavity, T2Rs are involved in the conscious perception of bitter tastants, while in the lower GI tract they have roles in chemoreception and regulation of GI function. Through these diverse roles, these receptors may be involved in modulating appetite and diet, with consequences for weight regulation and obesity. Interestingly, the concentration of T2Rs in the GI tract is greatest in the large intestine, the organ with the densest colonisation of bacteria. The gut microbiome has been the subject of intense research, as a plethora of roles linking microbiota to human health continue to be uncovered. Of particular interest is the microbial signature associated with obesity. Obesity is a leading health concern, and advances in our understanding of this disease are needed. Diet is a known modifiable factor in the development of obesity. However, diet only partially explains disease risk. Changes in microbial energy harvesting by the microbiota plays a role in obesity, and the composition of these energy harvesting populations may be controlled by taste receptors. This review explores T2Rs as a potential link between obesity and the human GI microbiome

Challenges in translating scientific evidence into mandatory food fortification policy: an antipodean case study of the folate- neural tube defect relationship

Objective: To identify challenges in translating scientific evidence of a&nbsp; nutrient and health relationship into mandatory food fortification policy. Design: A case study approach was used in which available evidence&nbsp; associated with the folate&ndash;neural tube defect relationship was reviewed against the Australia New Zealand Food Regulation Ministerial Council\u27s Policy Guideline for mandatory food fortification. Results: Three particular challenges were identified. The first is knowing when and how to act in the face of scientific uncertainty. The second is knowing how to address the special needs of at-risk individuals without compromising the health and safety of the population as a whole. The third is to ensure that a policy is sufficiently monitored and evaluated. Conclusions: Despite the availability of compelling evidence of a relationship between a particular nutrient and a health outcome, a definitive policy response may not be apparent.&nbsp; Judgement and interpretation inevitably play significant roles in influencing whether and how authorities translate scientific evidence into mandatory food fortification policy. In relation to the case study, it would be prudent to undertake a risk&ndash;benefit analysis of policy alternatives and to implement nutrition education activities to promote folic acid supplement use among the target group. Should mandatory folate fortification be implemented,&nbsp; comprehensive monitoring and evaluation of this policy will be essential to know that it is implemented as planned and does more good than harm. In relation to mandatory food fortification policy-making around the world,&nbsp; ongoing national nutrition surveys are required to complement national policy guidelines.<br /

Intense Sweeteners, Taste Receptors and the Gut Microbiome: A Metabolic Health Perspective

Intense sweeteners (IS) are often marketed as a healthier alternative to sugars, with the potential to aid in combating the worldwide rise of diabetes and obesity. However, their use has been counterintuitively associated with impaired glucose homeostasis, weight gain and altered gut microbiota. The nature of these associations, and the mechanisms responsible, are yet to be fully elucidated. Differences in their interaction with taste receptors may be a potential explanatory factor. Like sugars, IS stimulate sweet taste receptors, but due to their diverse structures, some are also able to stimulate bitter taste receptors. These receptors are expressed in the oral cavity and extra-orally, including throughout the gastrointestinal tract. They are involved in the modulation of appetite, glucose homeostasis and gut motility. Therefore, taste genotypes resulting in functional receptor changes and altered receptor expression levels may be associated with metabolic conditions. IS and taste receptors may both interact with the gastrointestinal microbiome, and their interactions may potentially explain the relationship between IS use, obesity and metabolic outcomes. While these elements are often studied in isolation, the potential interactions remain unexplored. Here, the current evidence of the relationship between IS use, obesity and metabolic outcomes is presented, and the potential roles for interactions with taste receptors and the gastrointestinal microbiota in modulating these relationships are explored

Distribution of variants in multiple vitamin D-related loci (DHCR7/NADSYN1, GC, CYP2R1, CYP11A1, CYP24A1, VDR, RXRα and RXRγ) vary between European, East-Asian and Sub-Saharan African-ancestry populations

BackgroundThe frequency of vitamin D-associated gene variants appear to reflect changes in long-term ultraviolet B radiation (UVB) environment, indicating interactions exist between the primary determinant of vitamin D status, UVB exposure and genetic disposition. Such interactions could have health implications, where UVB could modulate the impact of vitamin D genetic variants identified as disease risk factors. However, the current understanding of how vitamin D variants differ between populations from disparate UVB environments is limited, with previous work examining a small pool of variants and restricted populations only.MethodsGenotypic data for 46 variants within multiple vitamin D-related loci (DHCR7/NADSYN1, GC, CYP2R1, CYP11A1, CYP27A1, CYP24A1, VDR, RXRα and RXRγ) was collated from 60 sample sets (2633 subjects) with European, East Asian and Sub-Saharan African origin via the NCBI 1000 Genomes Browser and ALFRED (Allele Frequency Database), with the aim to examine for patterns in the distribution of vitamin D-associated variants across these geographic areas.ResultsThe frequency of all examined genetic variants differed between populations of European, East Asian and Sub-Saharan African ancestry. Changes in the distribution of variants in CYP2R1, CYP11A1, CYP24A1, RXRα and RXRγ genes between these populations are novel findings which have not been previously reported. The distribution of several variants reflected changes in the UVB environment of the population’s ancestry. However, multiple variants displayed population-specific patterns in frequency that appears not to relate to UVB changes.ConclusionsThe reported population differences in vitamin D-related variants provides insight into the extent by which activity of the vitamin D system can differ between cohorts due to genetic variance, with potential consequences for future dietary recommendations and disease outcomes

Salt Taste Genotype, Dietary Habits and Biomarkers of Health: No Associations in an Elderly Cohort

A small amount of emerging research has observed variations between individual sensitivity, preference and intake of salt in the presence of single nucleotide polymorphisms (SNP) on the genes encoding salt taste receptors. Sodium intake is a significant risk factor for common diseases in elderly populations such as hypertension and cardiovascular disease; however, this does not fully explain the risk. Research into the influence of salt taste genetics on diet quality is yet to be undertaken and current research on indicators of health is limited and mixed in the direction of associations. Therefore, a secondary analysis of data from a well-characterised elderly cohort (the cross-sectional Retirement Health and Lifestyle Study, n = 536) was conducted to explore relationships between the salt taste-related SNP TRPV1-rs8065080 (assessed by Taqman genotyping assay), dietary habits and biomarkers of health. Data were analysed with standard least squares regression modelling and Tukey’s HSD post hoc tests. No association was found between the TRPV1-rs8065080 genotype, sodium intake or multiple diet quality indices (assessed by food frequency questionnaire). Sodium-related markers of health including blood pressure and markers of kidney function (urinary creatinine and albumin/creatinine ratio) and general health markers, such as Body Mass Index (BMI), were also not related to TRPV1-rs8065080 genotype. To date, this study is the most comprehensive investigation conducted to determine if the TRPV1-rs8065080 genotype relates to sodium intake and health markers influenced by sodium intake. Although no significant relationships were found, these findings are an important contribution to the limited body of knowledge surround this SNP. In addition to further research across other ages and cultures, the TRPV1-rs8065080 genotype may interact with other ion channels, and so further studies are required to determine if polymorphic variations influence sodium intake, diet and health. View Full-Tex

Micronutrients and bioactive compounds in oral inflammatory diseases

Oral disorders are a significant public health concern. Oral inflammatory diseases are periodontal infections, oral mucosal lesions, pulpal and periapical lesions. The aetiology is multi-factorial and usually associated with a microbial origin, often driven by the overconsumption of free sugars. However, the role of micronutrients in these processes is now becoming apparent. Most of these studies have emphasised on systemic inflammation, but now the trends have shifted towards the role of micronutrients in oral inflammation. The progression of periodontal disease and healing of the periodontal tissues can be modulated by nutritional status. There are numerous degenerative changes in oral mucosa which have been observed during specific micronutrient deficiencies. Recent studies have advocated the use of dietary supplementation of particular micronutrients to treat the oral inflammatory lesions along with their standard treatment procedures. The micronutrient supplementation can be orally administered or locally delivered. Previously reviewed articles usually lacked compiled information regarding all oral inflammatory diseases. The current review provides an insight into the role of nutrition in oral inflammatory diseases, including periodontal disorders, oral mucosal lesions, pulpal and periapical lesions