Impact of the occupational environment of a submerged submarine on cardiometabolic health of Royal Navy submariners.

OBJECTIVE: To determine the effect of prolonged exposure to a submarine environment on biomarkers of cardiometabolic risk in Royal Navy (RN) submariners. METHODS: Serum lipids (cholesterol (C), triglyceride (TG), low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), non-HDL-C), glucose, insulin and anthropometrics were compared within three RN submarine crews before and after submerged patrols of 12 or 6 weeks, and with a crew that remained ashore (SUB-HOME). Dietary intake and activity patterns were self-reported during each patrol. Differences were assessed in crew characteristics using one-way analysis of variance and in serum lipids using paired t-tests. RESULTS: Postpatrol, the mean body weight of submerged crews decreased (-1.4±4.2 kg, p=0.0001), but increased in SUB-HOME (1.9±1.8 kg, p=0.0001). Modest improvements in serum lipids (mean individual change (mmol/L); C=-0.3±0.7, p=0.0001; TG=-0.3±0.7, p=0.0001; HDL-C=-0.1±0.3, p=0.0001; non-HDL-C=-0.2±0.6, p=0.012), glucose (-0.2±0.5, p=0.0001) and insulin (-1.5±4.6 mU/L, p=0.001) were observed in submerged crews. Changes in serum lipids were positively associated with changes in body weight within crews combined. Energy intake was maintained during submerged patrols but was lower compared with non-submerged (11 139±2792 vs. 9617±2466 kJ, p=0.001; 11 062±2775 vs. 9632±2682 kJ, p=0.003). CONCLUSIONS: The environment of a submerged submarine produced no adverse effects on serum biomarkers of cardiometabolic risk in crew. Conversely, modest improvements in these biomarkers were associated with a decrease in body weight.

An observational objective job analysis of role related tasks undertaken by Royal Navy sailors.

BACKGROUND: The current in-service Royal Naval Fitness Test has two elements to test the aerobic endurance and muscular strength of Service Personnel through generic field-based tests and a short job task simulation. However, in 2017 the Royal Navy (RN) identified a requirement to update their in-service fitness test to align with international best practice. OBJECTIVE: The purpose of this study was to conduct an Objective Job Task Analysis on critical, physically demanding tasks that could be undertaken by RN sailors during sea deployments. METHODS: Twenty-one training exercises were observed across a range of contexts; Type 23 Frigates, Type 45 Destroyers and at shore-based training facilities. A total of 203 RN personnel (age 27.8±7.1 years) were observed undertaking 36 job related tasks (e.g., 'firefighting', 'damage control', 'abandon ship' and 'casualty handling'). Tasks were evaluated by cardiovascular response, primary functional movements and contextual factors to aid a Military Judgement Panel in task list down-selection. RESULTS: 14 Criterion Tasks (e.g., 'firefighting', 'two-person magazine stowage' and 'casualty handling') were selected to progress to the next stage of the process. Five tasks were selected based on cardiovascular responses and a further nine tasks selected based on task ergonomics and other factors. CONCLUSION: This research has identified and quantified the most physically demanding, critical roles undertaken by RN sailors on sea deployments and will inform the development of the RN Physical Employment Standard.

Population variation in anti-S. aureus IgG isotypes influences surface protein A mediated immune subversion.

BACKGROUND: Staphylococcus aureus is a pathogen which causes life-threatening infection, the incidence of which rises during adult life. This, together with the emergence of drug-resistant strains and the expansion of more susceptible elderly populations, represents the rationale for the ongoing development of S. aureus vaccines targeting adult populations. Humoral responses to S. aureus naturally develop early in life, influence susceptibility to infection, and potentially influence the effect of vaccination. Despite this, the nature of pre-existing anti-S. aureus antibodies in healthy adult populations is not fully characterised. METHODS: Immunoglobulin levels against S. aureus surface antigens were measured by a filter membrane enzyme-linked immunosorbent assay using fixed ΔSpA S. aureus as an antigen in serum samples obtained from three clinical cohorts comprising 133 healthy adult volunteers from 19 to 65 years of age. Functional capacity of antibody was also assessed, using antibody-mediated attachment of FITC-stained S. aureus to differentiated HL-60 cells. RESULTS: Wide variation in the concentrations of immunoglobulins recognising S. aureus surface antigens was observed among individuals in all three cohorts. There was a decline of anti-S. aureus IgG1 with age, and a similar trend was observed in IgM, but not in IgA or other IgG sub-classes. Antibody mediated bacterial attachment to cells was associated with IgG1 and IgG3 concentrations in serum. The presence of SpA on the bacterial cell surface reduced antibody-mediated binding of bacteria to phagocytes in serum with low, but not high, levels of naturally occurring anti-S. aureus IgG3 antibodies. CONCLUSIONS: Naturally acquired immunoglobulin responses to S. aureus are heterogeneous in populations and their concentrations alter during adulthood. Elevated IgG1 or IgG3 titres against S. aureus enhance S. aureus recognition by phagocytosis and may be correlates of natural protection and/or vaccine efficacy in adult populations.

Risk factors for dermatitis in submariners during a submerged patrol: an observational cohort study.

OBJECTIVE: The aim of this pilot study was to determine risk factors, including Staphylococcus aureus nasal carriage, for dermatitis in submariners during a submarine patrol. PARTICIPANTS AND METHODS: 36 submariners undertaking a submerged 6-week patrol participated in the study. Severity of dermatitis and its impact was assessed using visual analogue scales and questionnaires at baseline and weekly throughout the patrol. S. aureus carriage levels in submariners were determined by nasal swabbing at baseline and shortly before disembarking the submarine. Occurrence of any skin or soft tissue infections (SSTI) were reported to the medical officer and swabs of the area were taken for subsequent analysis. RESULTS: S. aureus carriers were significantly more likely than non-carriers to have previously received treatment for a cutaneous abscess (39% vs 5%, OR=13 (95% CI 1.3 to 130)) with a trend to being submariners longer (p=0.051). Skin scores at baseline and on patrol were not significantly associated with carriage status. Higher dermatitis scores were observed in those who had been submariners longer (p=0.045). Smoking and allergies were not found to be linked to carriage status or skin health score in this cohort. CONCLUSIONS: This small pilot study investigates S. aureus carriage status and skin health in submariners. Length of submarine service but not S. aureus carriage was identified as a risk factor for worsening skin health in this small cohort during a 6-week patrol. This does not support S. aureus decolonisation to improve skin health in this population. Further investigation into causes of dermatitis in submariners is required. This data supports a better understanding of the potential impact of exposure to environmental factors that could affect skin health in submariners.

Applications of multi-nuclear magnetic resonance spectroscopy at 7T.

AIM: To discuss the advantages of ultra-high field (7T) for (1)H and (13)C magnetic resonance spectroscopy (MRS) studies of metabolism. METHODS: Measurements of brain metabolites were made at both 3 and 7T using (1)H MRS. Measurements of glycogen and lipids in muscle were measured using (13)C and (1)H MRS respectively. RESULTS: In the brain, increased signal-to-noise ratio (SNR) and dispersion allows spectral separation of the amino-acids glutamate, glutamine and γ-aminobutyric acid (GABA), without the need for sophisticated editing sequences. Improved quantification of these metabolites is demonstrated at 7T relative to 3T. SNR was 36% higher, and measurement repeatability (% coefficients of variation) was 4%, 10% and 10% at 7T, vs 8%, 29% and 21% at 3T for glutamate, glutamine and GABA respectively. Measurements at 7T were used to compare metabolite levels in the anterior cingulate cortex (ACC) and insula. Creatine and glutamate levels were found to be significantly higher in the insula compared to the ACC (P < 0.05). In muscle, the increased SNR and spectral resolution at 7T enables interleaved studies of glycogen ((13)C) and intra-myocellular lipid (IMCL) and extra-myocellular lipid (EMCL) ((1)H) following exercise and re-feeding. Glycogen levels were significantly decreased following exercise (-28% at 50% VO(2) max; -58% at 75% VO(2) max). Interestingly, levels of glycogen in the hamstrings followed those in the quadriceps, despite reduce exercise loading. No changes in IMCL and EMCL were found in the study. CONCLUSION: The demonstrated improvements in brain and muscle MRS measurements at 7T will increase the potential for use in investigating human metabolism and changes due to pathologies.

The influence of carbohydrate and protein ingestion during recovery from prolonged exercise on subsequent endurance performance.

Ingesting carbohydrate plus protein following prolonged exercise may restore exercise capacity more effectively than ingestion of carbohydrate alone. The objective of the present study was to determine whether this potential benefit is a consequence of the protein fraction per se or simply due to the additional energy it provides. Six active males participated in three trials, each involving a 90-min treadmill run at 70% maximal oxygen uptake (run 1) followed by a 4-h recovery. At 30-min intervals during recovery, participants ingested solutions containing: (1) 0.8 g carbohydrate x kg body mass (BM)(-1) h(-1) plus 0.3 g kg(-1) h(-1) of whey protein isolate (CHO-PRO); (2) 0.8 g carbohydrate x kg BM(-1) h(-1) (CHO); or (3) 1.1 g carbohydrate x kg BM(-1) h(-1) (CHO-CHO). The latter two solutions matched the CHO-PRO solution for carbohydrate and for energy, respectively. Following recovery, participants ran to exhaustion at 70% maximal oxygen uptake (run 2). Exercise capacity during run 2 was greater following ingestion of CHO-PRO and CHO-CHO than following ingestion of CHO (P< or = 0.05) with no significant difference between the CHO-PRO and CHO-CHO treatments. In conclusion, increasing the energy content of these recovery solutions extended run time to exhaustion, irrespective of whether the additional energy originated from sucrose or whey protein isolate.