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Actions to enhance survival in a distressed submarine (DISSUB) scenario may be guided in part by knowledge of the likely risk of decompression sickness (DCS) should the crew attempt tower escape. A mathematical model for DCS risk estimation has been calibrated against DCS outcome data from 3,738 exposures of either men or goats to raised pressure. Body mass was used to scale DCS risk. The calibration data included more than 1,000 actual or simulated submarine escape exposures and no exposures with substantial staged decompression. Cases of pulmonary barotrauma were removed from the calibration data. The calibrated model was used to estimate the likelihood of DCS occurrence following submarine escape from the United Kingdom Royal Navy tower escape system. Where internal DISSUB pressure remains at - 0.1 MPa, escape from DISSUB depths < 200 meters is estimated to have DCS risk < 6%. Saturation at raised DISSUB pressure markedly increases risk, with > 60% DCS risk predicted for a 200-meter escape from saturation at 0.21 MPa. Using the calibrated model to predict DCS for direct ascent from saturation gives similar risk estimates to other published models.

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The Royal Navy requires reliable advice on the safe limits of escape from a distressed submarine (DISSUB). Flooding in a DISSUB may cause a rise in ambient pressure, increasing the risk of decompression sickness (DCS) and decreasing the maximum depth from which it is safe to escape. The aim of this study was to investigate the pressure/depth limits to escape following saturation at raised ambient pressure. Exposure to saturation pressures up to 1.6 bar (a) (160 kPa) (n = 38); escapes from depths down to 120 meters of sea water (msw) (n = 254) and a combination of saturation followed by escape (n = 90) was carried out in the QinetiQ Submarine Escape Simulator, Alverstoke, United Kingdom. Doppler ultrasound monitoring was used to judge the severity of decompression stress. The trials confirmed the previously untested advice, in the Guardbook, that if a DISSUB was lying at a depth of 90 msw, then it was safe to escape when the pressure in the DISSUB was 1.5 bar (a), but also indicated that this advice may be overly conservative. This study demonstrated that the upper DISSUB saturation pressure limit to safe escape from 90 msw was 1.6 bar (a), resulting in two cases of DCS.

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The distribution of salmeterol and proxicromil between unilamellar vesicles of dioleoylphosphatidylcholine (DOPC) and aqueous buffer at pH 7.4 has been studied, using an ultrafiltration method, as a function of compound concentration, DOPC concentration, and buffer ionic strength. The binding of these ionized lipophilic compounds to neutral DOPC vesicles induces a surface charge, which causes the observed membrane distribution coefficient D(mem)obs to vary significantly with bound compound to DOPC ratio and with ionic strength. This variability is shown to be well-described with use of the Gouy-Chapman theory of the ionic double layer and is contrasted with the ideal behavior shown by the neutral compound clofibrate. Increasing ionic strength is also shown to increase the observed 1-octanol-buffer distribution coefficients D(o/w)obs of proxicromil but through a very different mechanism involving the extraction of ion pairs. This study highlights the experimental difficulty in determining concentration-independent liposome distribution coefficients of ionized lipophilic compounds and describes when deviations will be significant and how observed values may be corrected for such effects. The general effect of ionic strength on membrane-buffer distribution and 1-octanol-buffer distribution is discussed with particular reference to the very different propensity for ion pair formation shown by the two systems, and the most suitable experimental conditions that should be used with each system.

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Immune function, particularly cell-mediated immunity (CMI), declines with age and it has been suggested that this may be secondary to the impaired nutritional status often found in the elderly. In the present study a balanced nutritional supplement consisting of several macro- and micro-nutrients was administered daily to 27 housebound elderly (aged 70-85 years) for 12 weeks. Thirty-one matched subjects served as a control group. Delayed cutaneous hypersensitivity (DCH) to seven recall antigens was measured using the Mérieux Multitest CMI device and total numbers of lymphocytes, B-cells, T-cells and T-cell sub-populations were determined using monoclonal antibodies. These tests and several indices of nutritional status were measured before and at the end of the 12-week study. Before supplementation 19% of the entire group of subjects were anergic and another 19% hypoergic, values greater than expected for healthy elderly subjects. A weak association (P = 0.056) was shown between plasma zinc concentration and the number of positive skin test responses. Supplementation had minimal effect on DCH, resulting in a significant (P < 0.05) increase only in the sum of positive indurations. Pre-study numbers of total lymphocytes and lymphocyte sub-populations were as expected for healthy elderly subjects, but a correlation was found between plasma selenium concentrations (mean 1.07, range 0.64-1.66 mumol/l) and the numbers of CD4 lymphocytes (P < 0.01). Supplementation did not result in a significant change in any of the lymphocyte populations.(ABSTRACT TRUNCATED AT 250 WORDS)

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The iron status of housebound and hospitalized elderly people was studied by duplicate diet analysis, metabolic balance, biochemical and haematological investigations. Evidence of biochemical iron deficiency in the hospital group was accompanied by low dietary intake and negative metabolic balance. Metabolic equilibrium in the housebound group was seen with intakes similar to those found in healthy elderly though biochemical measures suggested a borderline iron deficient state.

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1. Metabolic balance studies (5 d) for Se were conducted in twenty-four apparently healthy elderly people (age 69.6-85.4 years), and twenty housebound subjects (age 69.9-85.1 years) with chronic disease. During the study the subjects lived in their own homes, ate self-selected diets and continued their normal daily activities. 2. Geometric mean daily dietary intakes of the two groups were significantly different (P less than 0.01), being 819 (range 310-1631) nmol for the healthy and 475 (range 233-1136) nmol for the housebound elderly. 3. Daily intake of Se significantly correlated with balance in both groups. Solution of the regression equations gave theoretical daily requirements of 447 nmol for the healthy and 419 nmol for the housebound subjects. The healthy elderly were in positive balance of 148 nmol/d for Se and the housebound were in equilibrium with an overall mean retention of 43 nmol/d. 4. Mean levels of Se in blood fractions for the healthy and housebound subjects were significantly different, being 1.65 and 1.40 mumol/l whole blood, 1.45 and 1.21 mumol/l plasma and 5.72 and 5.30 nmol/g haemoglobin in erythrocytes respectively. There was no difference in the whole-blood glutathione peroxidase (EC 1.11.1.9) activities between the two groups. 5. There were clear differences in Se status between the two groups of elderly people. The cause of the positive balance in the healthy subjects remains unexplained.

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Five-day metabolic balance studies for zinc and copper were carried out in 20 housebound elderly people with stable chronic diseases. Subjects were age 70.0-85.1 y, lived in their own homes, and ate self-selected diets. Mean daily intakes for Zn and Cu were 90 mumol and 13.4 mumol with mean negative balances of -16 and -1.1 mumol, respectively. Both balance values significantly differed from equilibrium (p less than 0.05). For Zn and Cu, respectively, mean concentrations were 11.3 and 22.1 mumol/L plasma, 103 and 19.4 mumol/L whole blood, and 98 and 8.7 pmol/10(6) leukocytes. The results for Zn and Cu balance and leukocyte concentrations were different from those obtained by us for healthy elderly people (Am J Clin Nutr 1984;40: 1096-120). A highly significant (r = 0.75, p less than 0.001) correlation was observed between zinc balance and leukocyte zinc concentrations.

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Metabolic balance studies (5 d) for nitrogen were carried out in twenty-four apparently healthy elderly people (age 69.7-85.6 years) and a heterogeneous group of twenty housebound elderly people (age 69.9-85.1 years) with chronic diseases. During the study all subjects ate self-selected diets, lived in their own homes and continued their normal daily activities. Seven of the housebound received meals-on-wheels 5 d/week. Healthy men and women had mean metabolizable energy intakes of 8.7 and 6.6 MJ/d respectively compared with 6.3 and 4.8 MJ/d in the housebound. The average energy content of the meals-on-wheels as delivered was 2.4 MJ per meal, of which 2.1 MJ were consumed. The healthy men and women had average daily protein intakes of 69.4 and 59.7 g respectively compared with 46.3 and 39.1 g in the housebound. Meals-on-wheels as supplied provided 19.4 g protein per meal, of which 16.2 g were consumed. Healthy subjects were in equilibrium for N balance (0 mmol/d) with a daily intake of 733 mmol, which was equivalent to 11.04 mmol N (0.97 g mixed protein)/kg body-weight per d. Housebound individuals were in negative N balance (-95 mmol/d) with an intake of 475 mmol/d, corresponding to 7.59 mmol N (0.67 g mixed protein)/kg body-weight per d. We were unable to determine in the present study whether the negative N balance observed in the housebound people was due to the relatively low N intake or the underlying disease condition.

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The trace element and macronutrient contents of 35 different meals-on-wheels received by seven housebound elderly people have been analysed. The contribution these meals made to the existing Recommended Daily Allowance or the Safe and Adequate Dietary Intake as well as the overall daily nutrient intake was assessed. In general the meals provided adequate amounts of energy, protein, calcium, phosphorus, potassium and iron. Levels of magnesium, manganese, copper, chromium and zinc were low in comparison with some recommended intakes. In addition the meals appeared to contain a relatively high level of sodium. Recommendations for the nutrient content of meals-on-wheels have been made.

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Pulmonary function has been measured at intervals after direct chest injuries of mild and moderate severity in 46 patients. Ventilatory capacity (e.g. FEV1) and vital capacity were reduced and the residual volume was increased. Total lung capacity and alveolar volume were also reduced and as a result total pulmonary diffusing capacity (transfer factor) was decreased, however, the remaining lung had a normal diffusion coefficient. Intercostal nerve block at the fracture site did not improve ventilatory capacity although marked pain relief was achieved. Recovery was slower in those patients not admitted to hospital than in the more seriously injured patients who were admitted. It is suggested that more attention should be paid to the outpatient follow-up of such patients, perhaps paying particular attention to physiotherapy.

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Clinical findings in Leber's hereditary optic atrophy (LHOA) are reviewed and the results given of treatment with a regimen based on the hypothesis that the disease is a manifestation of cyanide toxicity. Recent biochemical investigations confirm disturbed cyanide metabolism and suggest that zinc deficiency may be implicated.

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