Diurnal changes in the photochemical efficiency of the symbiotic dinoflagellates (Dinophyceae) of corals: photoprotection, photoinactivation and the relationship to coral bleaching

The photochemical efficiency of symbiotic dinoflagellates within the tissues of two reef-building corals in response to normal and excess irradiance at wafer temperatures < 30 C were investigated using pulse amplitude modulated (PAM) chlorophyll fluorescence techniques, Dark-adapted F-v/F-m showed clear diurnal changes, decreasing to a low at solar noon and increasing in the afternoon. However, F-v/F-m also drifted downwards at night or in prolonged darkness, and increased rapidly during the early morning twilight. This parameter also increased when the oxygen concentration of the wafer holding the corals was increased. Such changes have not been described previously, and most probably reflect state transition's associated with PQ pool reduction via chlororespiration. These unusual characteristics may be a feature of an endosymbiotic environment, reflective of the well-documented night-time tissue hypoxia that occurs in corals. F-v/F-m decreased to 0.25 in response to full sunlight in shade-acclimated (shade) colonies of Stylophora pistillata, which is considerably lower than in light-acclimated (sun) colonies. In sun colonies, the reversible decrease in F-v/F-m was caused by a lowering of F-m and F-o suggesting photoprotection and no lasting damage. The decrease in F-v/F-m, however, was caused by a decrease in F-m and an increase in F-o in shade colonies suggesting photoinactivation and long-term cumulative photoinhibition. Shade colonies rapidly lost their symbiotic algae (bleached) during exposure to full sunlight. This study is consistent with the hypothesis that excess light leads to chronic damage of symbiotic dinoflagellates and their eventual removal from reef-building corals. It is significant that this can occur with high light conditions alone.

The reduction of itch during burn wound healing

The purpose of this study was to find a method to reduce the itch experienced by patients who have sustained burn injuries, by using and comparing the effectiveness of 2 shower and bath oils. One product contained liquid paraffin with 5% colloidal oatmeal and the other contained liquid paraffin. The study was carried out in the Adult Burns Unit, Royal Brisbane Hospital (RBH), Brisbane. It was conducted during a 10-month period from July 1998 until April 1999. Thirty-five acute burns patients participated in an assessor-blind clinical trial. Patients were asked twice daily to rate their discomfort from itch and pain. The amount of antihistamine requested by each patient was totalled daily. Analysis of data supplied by patients showed that the group using the product with colloidal oatmeal reported significantly less itch and requested significantly less antihistamine than those using the oil containing liquid paraffin.

A risk-based system to penalize and reward line management for occupational safety and health performance

Penalizing line management for the occurrence of lost time injuries has in some cases had unintended negative consequences. These are discussed. An alternative system is suggested that penalizes line management for accidents where the combination of the probability of recurrence and the maximum reasonable consequences such a recurrence may have exceeds an agreed limit. A reward is given for prompt effective control of the risk to below the agreed risk limit. The reward is smaller than the penalty. High-risk accidents require independent investigation by a safety officer using analytical techniques. Two case examples are given to illustrate the system. Continuous safety improvement is driven by a planned reduction in the agreed risk limit over time and reward for proactive risk assessment and control.

Genetics of Serum Dehydroepiandrosterone Sulfate and Its Relationship to Insulin in a Population-Based Cohort of Twin Subjects

Previous studies have shown a significant effect of insulin administration on serum dehydroepiandrosterone sulfate (DHEA-S) concentration and its metabolic rate, with evidence for the effect in men, but not in women. This could lead to differences in the sources of variation in serum DHEA-S between men and women and in its covariation with insulin concentration. This study aimed to test whether these hypotheses were supported in a sample of healthy adult twins. Serum DHEA-S (n=2287) and plasma insulin (n=2436) were measured in samples from adult male and female twins recruited through the Australian Twin Registry. Models of genetic and environmental sources of variation and covariation were tested against the data. DHEA-S showed substantial genetic effects in both men and women after adjustment for covariates, including sex, age, body mass index, and time since the last meal. There was no significant phenotypic or genetic correlation between DHEA-S and insulin in either men or women. Despite the experimental evidence for insulin infusion producing a reduction in serum DHEA-S and some effect of meals on the observed DHEA-S concentration, there were no associations between insulin and DHEA-S at the population level. Variations in DHEA-S are due to age, sex, obesity, and substantial polygenic genetic influences.

Clinical assessment of HIV-associated lipodystrophy syndrome: bioelectrical impedance analysis, anthropometry and clinical scores

Background Diagnosis of the HIV-associated lipodystrophy syndrome is based on clinical assessment, in lack of a consensus about case definition and reference methods. Three bedside methods were compared in their diagnostic value for lipodystrophy. Patients and Methods. Consecutive HIV-infected outpatients (n = 278) were investigated, 128 of which also had data from 1997 available. Segmental bioelectrical impedance analysis (BIA) and waist, hip and thigh circumferences were performed. Changes in seven body regions were rated by physicians and patients using linear analogue scale assessment (LASA). Diagnostic cut-off values were searched by receiver operator characteristics. Results. Lipodystrophy was diagnosed in 85 patients (31%). BIA demonstrated higher fat-free mass in patients with lipodystrophy but not after controlling for body mass index and sex. Segmental BIA was not superior to whole body BIA in detecting lipodystrophy. Fat-free mass increased from 1997 to 1999 independent from lipodystrophy. Waist-hip and waist-thigh ratios were higher in patients with lipodystrophy. BIA, anthropometry and LASA did not provide sufficient diagnostic cut-off values for lipodystrophy. Agreement between methods, and between patient and physician rating, was poor. Conclusion: These methods do not fulfil the urgent need for quantitative diagnostic tools for lipodystrophy. BIA estimates of fat free mass may be biased by lipodystrophy, indicating a need for re-calibration in HIV infected populations. (C) 2001 Harcourt Publishers Ltd.

The breeding-season diet of wedge-tailed eagles (Aquila audax) in western New South Wales and the influence of Rabbit Calicivirus Disease

A total of 2071 individual prey items were identified from 34 active and 55 inactive wedge-tailed eagle nests following the 1995, 1996 and 1997 breeding seasons. Overall, the eagle's diet was comparable to that reported in other studies within semi-arid regions, with rabbits, reptiles and macropods accounting for 47.8, 22.6 and 13.7% of prey items, respectively. In spring 1996 rabbit calicivirus moved into the study area, resulting in a 44-78% reduction in rabbit abundance (Sharp et al. 2001). An index was developed to enable the time since death for individual prey items to be approximated and a historical perspective of the eagle's diet to be constructed. Rabbits constituted 56-69% of dietary items collected during the pre-rabbit calicivirus disease (RCD) samples, but declined to 31% and 16% in the two post-RCD samples. A reciprocal trend was observed for the proportion of reptiles in the diet, which increased from 8-21% of pre-RCD dietary items to 49-54% after the advent of RCD. Similarly, the proportion of avian prey items was observed to increase in the post-RCD samples. These data suggested that prey switching may have occurred following the RCD epizootic. However, a lack of data on the relative abundances of reptiles and birds prevented an understanding of the eagle's functional responses to be developed and definitive conclusions to be drawn. Nevertheless, the eagles were observed to modify their diet to the change in rabbit densities by consuming larger quantities of native prey species.

A new technique for the quantification of peripheral edema with application in both unilateral and bilateral cases

Current noninvasive techniques for the routine and frequent quantification of peripheral lymphedema in patients are total limb volume measurement (by water immersion or by circumferential measurements) and bioelectrical impedance analysis (BIA). However both of these techniques require standardizing the measurement using a contralateral measurement from the unaffected limb, Hence these techniques are essentially restricted to unilateral lymphedema. This paper describes the results from a preliminary study to investigate an alternative approach to the analysis of the data from multiple frequency BIA to produce an index of lymphedema without the need for normalization to another body segment. Twenty patients receiving surgical treatment for breast cancer were monitored prior to surgery and again after diagnosis with unilateral lymphedema. The data recorded were total limb volume, by circumferential measurements; and BIA measurements of both limbs. From these measurements total limb volumes and extracellular fluid volumes were calculated and expressed as ratios of the affected limb to that of the unaffected limb. An index of the ratio of the extracellular fluid volume to the intracellular fluid volume was determined. This ECW/ICW index was calculated for both the affected and unaffected limbs at both measurement times. Results confirmed that the established techniques of total limb volume and extracellular fluid volume normalized to the unaffected contralateral limb were accurate in the detection of lymphedema (p < 10(-6)). Comparison of the ECW/ICW index from the affected limb after diagnosis with that from the pre-surgery measurement revealed a significant (p< 10(-6)) and considerable (75%) increase. The results of this pilot study suggest that by using multiple frequency bioelectrical impedance analysis, an index of the ECW/ICW ratio can be obtained and this index appears to have an equal, or better, sensitivity, than the other techniques in detecting lymphedema. More importantly, this index does not require normalization to another body segment and can be used to detect all types of peripheral edema including both unilateral and bilateral lymphedema.