Genetic correlation in relation to differences in dosage of a stressor

We exposed the strains of Chlamydomonas isolated from an outbred laboratory population to a range of concentrations of salt (NaCl) up to an extirpative level that the base population could not tolerate. The genetic variance of yield increased with stress over the first half of this range before collapsing to nearly zero. The genetic correlation decreased with environmental distance, whether measured as a difference in dosage or as an environmental variance. This result is consistent with previous studies and provides a basis for interpreting adaptation to a deteriorating environment and the process of evolutionary rescue.

How to reduce morbidity and mortality from chest infections in rheumatoid arthritis

Morbidity and mortality from pneumonia is increased in patients with rheumatoid arthritis. Factors contributing to this have been recently identified and a number of recommendations have been implemented in an attempt to reverse this trend. The present paper shows that these measures have combined to produce a fourfold reduction in both admissions and case fatality rates. In the study population, immunisation rates against influenza and pneumococcus have improved to 86% and 65%, oral steroid consumption has halved and disease modifying drugs were usually appropriately suspended during acute infection. These measures may now merit more widespread adoption.

The development and reliability of a repeated anaerobic cycling test in female ice hockey players

The purpose of this study was to develop and assess the reliability of a repeated anaerobic power cycling test designed to mimic the repeated sprinting nature of the sport of ice hockey. Nineteen female varsity ice hockey players (mean X +/- SD age, height and body mass = 21 +/- 2 yr, 166.6 +/- 6.3 cm and 62.3 +/- 7.3) completed 3 trials of a repeated anaerobic power test on a Monark cycle ergometer on different days. The test consisted of "all-out" cycling for 5 seconds separated by 10 seconds of low-intensity cycling, repeated 4 times. The relative load factor used for the resistance setting was equal to 0.095 kg per kilogram body mass. There was no significant difference between the peak 5-second power output (PO), mean PO, or the fatigue index (%) among the 3 different trials. The peak 5-second PO was 702.6 +/- 114.8 w and 11.3 +/- 1.1 w x kg, whereas the mean PO across the 4 repeats was 647.1 +/- 96.3 w and 10.4 +/- 1.0 w x kg averaged for the 3 different tests. The fatigue index averaged 17.8 +/- 6.5%. The intraclass correlation coefficient for peak 5-second, mean PO, and fatigue index was 0.82, 0.86, and 0.82, respectively. This study reports the methodology of a repeated anaerobic power cycling test that was reliable for the measurement of PO and calculated fatigue index in varsity women ice hockey players and can be used as a laboratory-based assessment of repeated anaerobic fitness.

Adaptation of experimental yeast populations to stressful conditions in relation to population size

The purpose of this experiment was to find out how a population becomes adapted to extremely stressful conditions as its environment deteriorates. We created a deteriorating environment for experimental selection lines of yeast by a stepwise increase in the concentration of salt in the growth medium. After each step, we tested the ability of the lines to grow at a high concentration of salt near the lethal limit for the ancestral strain. We found that mutations enhancing growth in this highly stressful environment began to spread at intermediate salt concentrations. The degree of enhancement was related to effective population size by a power law with a small exponent. The effect size of these mutations also increased with the population size in a similar fashion. From these results, we interpret adaptation to lethal stress as an indirect response to selection for resistance to previous lower levels of stress in a deteriorating environment. This suggests that the pattern of genetic correlation between successively higher levels of stress is an important factor in facilitating evolutionary rescue.

The oligogenic view of adaptation

The traditional view is that evolution proceeds very slowly, over immense periods of time, driven by weak selection acting on innumerable genes of small effect. Recent studies of rapid evolution, in the laboratory and in the field, have given a radically different picture. Although beneficial mutations tend to be small in effect when they first appear, those that survive to spread and become fixed are usually among the minority with large effect. Hence, although hundreds of loci of small effect may contribute to variation in character state, adaptation is predominantly caused by alleles of large effect. This leads to the hope that the particular mutations responsible for adaptation to altered conditions of life can be identified and characterized. This has been achieved in some cases and may soon become routine. Furthermore, it raises the possibility that adaptive change can be predicted from a knowledge of genetics and ecology. Experimental evolution suggests that any given selection line that is adapting to changed conditions will follow one of a few themes (broadly speaking, loci), each of which may have many variations (mutations within the locus producing similar phenotypes). Hence, evolutionary change can be predicted only within limits, even in principle. Nevertheless, recent attempts to predict how very simple genomes change have been surprisingly successful, and we may be close to a new predictive understanding of the genetic basis of adaptation.

Whole blood and mononuclear cell glutathione response to dietary whey protein supplementation in sedentary and trained male human subjects

Sedentary male subjects (n=9) on a controlled diet were fed two doses (0.8 or 1.6 g/kg body mass) of a whey protein isolate (WPI), in addition to an isocaloric placebo; blood samples were drawn over a 4-h period and glutathione concentration determined. There was no effect of the supplementation at either level over the 4-h sampling period. The effects of a WPI supplemented diet on glutathione concentrations in whole blood as well as peripheral mononuclear cell populations were also investigated over a 6-week period in male subjects (n=18) involved in arduous aerobic training; blood was collected prior to and following a 40 km simulated cycling trial. The aerobic training period resulted in significantly lower glutathione concentrations in whole blood, an effect that was mitigated by WPI supplementation. A significant increase in mononuclear cell glutathione was also observed in subjects receiving the WPI supplement following the 40 km simulated cycling trial.

Plasminogen activator inhibitor type 1 up-regulation is associated with skeletal muscle atrophy and associated fibrosis

Muscle wasting remains a feature of many diseases and is counteracted by anabolic supplementation or exercise. Persisting atrophy-inducing conditions can be complicated by skeletal muscle fibrosis, which leads to functional impairment. Identification of early mechanisms that initiate atrophy-induced fibrosis may reveal novel targets for therapy or diagnosis. Therefore, we investigated changes in the expression of genes involved in extracellular matrix homeostasis during glucocorticoid-induced atrophy of myotubes and compared them with insulin-like growth factor-1-induced hypertrophy. Obtained results were verified in rat gastrocnemius muscle that was exposed to microgravity by space flight for 2 weeks. Myostatin and atrogin-1 mRNA levels reflected the magnitude of atrophy. Despite differential induction of these negative muscle mass regulators, no major changes in matrix metalloproteinases-2, -9, and -14 mRNAs or their physiological inhibitors could be detected in either atrophy model. In contrast, transcript levels of plasminogen activator inhibitor type 1 (PAI-1) was dramatically increased in atrophic myotubes and microgravity-exposed rat gastrocnemius muscle, while plasminogen activators remained unaltered. In contrast to atrophy, no increase in PAI-1 mRNA levels could be detected in rat hindlimb that was electrically stimulated for 21 days. Furthermore, a strong increase in PAI-1 mRNA levels was identified in skeletal muscle of patients with neurogenic muscle atrophy. Our study suggests that increased PAI-1 expression in atrophic skeletal muscle may lead to muscle fibrosis by reducing plasmin generation.

A 26 year physiological description of a National Hockey League team

The primary purpose of this investigation was to examine the physiological profile of a National Hockey League (NHL) team over a period of 26 years. All measurements were made at a similar time of year (pre-season) in 703 male (mean age ± SD = 24 ± 4 y) hockey players. The data were analyzed across years, between positions (defensemen, forwards, and goaltenders), and between what were deemed successful and non-successful years using a combination of points acquired during the season and play-off success. Most anthropometric (height, mass, and BMI) and physiological parameters (absolute and relative VO2 peak, relative peak 5 s power output, abdominal endurance, and combined grip strength) showed a gradual increase over the 26 year period. Defensemen were taller and heavier, had higher absolute VO2 peak, and had greater combined grip strength than forwards and goaltenders. Forwards were younger and had higher values for relative VO2 peak. Goaltenders were shorter, had less body mass, a higher sum of skinfolds, lower VO2 peak, and better flexibility. The overall pre-season fitness profile was not related to team success. In conclusion, this study revealed that the fitness profile for a professional NHL ice-hockey team exhibited increases in player size and anaerobic and aerobic fitness parameters over a 26 year period that differed by position. However, this evolution of physiological profile did not necessarily translate into team success in this particular NHL franchise.

Paediatric day-case surgery: an audit of unplanned hospital admission Royal Hospital for Sick Children, Glasgow

Audit of unplanned hospital admission provides information to guide quality improvement measures and is a crude indicator of quality of care in ambulatory surgery. Our objectives were to re-audit factors relating to this outcome. Previous audit conducted in this unit revealed an unplanned admission rate of 3.7%. Data were collected between April 2000-March 2004. Of 13 592 day surgery patients, 238 (1.8%) unplanned admissions occurred. The admission rate displayed a falling trend and represented a significant improvement over the previous audit (p < 0.001). Unplanned admissions were most commonly caused by nausea/vomiting 23.5% (n = 56), postoperative bleeding 13.9% (n = 34), and unexpected extent/difficulty of procedure 11.8% (n = 28). Of all admissions, 18.5% (n = 44) were following orchidopexy, 16.4% (n = 39) following circumcision, and 12.6% (n = 30) following dental extraction. This audit shows that the unplanned admission rate is low and falling, and compares favourably with other units. Measures have been implemented targeting patients at high risk of admission.

The application of ToF-SIMS to the analysis of herbicide formulation penetration into and through leaf cuticles

Understanding the movement of the active ingredient in relation to the other formulation components following application is crucial to an overall understanding of herbicide performance. We describe the novel use of time-of-flight secondary ion mass spectrometry (ToF-SIMS) as a tool for following the movement of herbicide formulation components into and across plant cuticles. This technique provides new insights since it provides both high (sub-micron) spatial resolution combined with the chemical specificity associated with organic mass spectrometry. The components studied include the oligomeric ethoxylate surfactants Synperonic A7 and A20 and active ingredient Sulfosate (trimesium glyphosate). The movement of these molecules, both separately and when combined in a simple formulation, into the surface of Prunus laurocerasus leaves and across the isolated plant cuticle was investigated and clear differences in penetration/diffusion behaviour were identified. ToF-SIMS was uniquely able to (simultaneously) spatially resolve all the species involved, including the anion and cation components of the active ingredient. Also, using spectral reconstructions from the imaging raw data streams, the behaviour of individual oligomers within the surfactant distributions, could be assessed. The observations are discussed with reference to the action of surfactants identified in parallel micro-structural studies and the current understanding of herbicide uptake.

Masquerade: medical causes of back pain

Back pain has many causes, and 95% of cases are due to benign, self-limiting problems. Most problems are musculoskeletal and are relieved with rest and nonsteroidal medications. However, some serious and life-threatening medical conditions also can present as acute back pain.

The evolution of trophic structure

The trophic relationships of an ecological community were represented by digital individuals consuming resources or prey within a simulated ecosystem and producing offspring that may differ from their parents. When individuals meet, a few simple rules are used to decide the outcome of their interaction. Trophically complex systems persist for long periods of time even in finite communities, provided that the strength of predator-prey interaction is sufficient to repay the cost of maintenance. The topology of the food web and important system-level attributes such as overall productivity follow from the rules of engagement: that is, the macroscopic properties of the ecosystem follow from the microscopic attributes of individuals, without the need to invoke the emergence of novel processes at the level of the whole system. Evolutionarily stable webs exist only when the pool of available species is small. If the pool is large, or speciation is allowed, species composition changes continually, while overall community properties are maintained. Ecologically separate and topologically different source webs based on the same pool of resources usually coexist for long periods of time, through negative frequency-dependent selection at the level of the source web as a whole. Thus, the evolved food web of species-rich communities is a highly dynamic structure with continual species turnover. It both imposes selection on each species and itself responds to selection, but selection does not necessarily maximize stability, productivity or any other community property.

An audit of 600 referrals to a primary care based oral surgery service

AIM

To identify potential problems in the quality of care when oral surgery is provided in the primary health care setting.

METHOD

Retrospective analysis of referral patterns, waiting times, treatment with clinical and histological diagnosis, including complications of 600 patients referred to a practice-based oral surgical referral service.

RESULTS

Fifty-three patients were not treated. Seventy-nine percent of patients were treated within four weeks of referral. The most common procedure performed was surgical removal of impacted third molar teeth. The most frequently observed complications were dry socket (n = 31/703), pain and inflammation associated with resorbable sutures (n = 11/453), and post-operative infection (n = 9/547). One patient with post-operative infection required care in the acute hospital setting.

CONCLUSION

Acknowledging the small sample, it was safe and effective to diagnose and treat a broad spectrum of patients and oral surgical problems in the primary health care setting.

Comparison of methods of assessment of renal function in cystic fibrosis (CF) patients

Renal failure is increasingly being recognised in CF patients, usually as a consequence of long-term nephrotoxic therapy. There is a need for a simple method of assessment of renal function in this patient group. We compared measured creatinine clearance from validated timed urine collections (the generally accepted practical test of glomerular filtration) with 10 formulae used to estimate creatinine clearance in a group of 74 CF adult patients and 29 matched normal controls. Compared to direct measurement, formulae gave a range of values (95% CI for mean bias -13 to +27.9 ml/min). Even those with the best correlation (r=0.7) gave wide error ranges (limits of agreement: -42.3 to 45.9 ml/min). The most commonly used formulae (Cockroft-Gault [CGF] and abbreviated Modification of Diet in Renal Disease [aMDRD]) were not superior to most other formulae tested. Both CGF and aMDRD-derived estimates compared less favourably in CF patients than controls (mean bias: 9.7 vs 3.4 ml/min (p<0.05) and 4.9 vs 1.4 (p<0.05) respectively; 78% vs 95% (p<0.01) and 77% vs 97% (p<0.01) of estimates within 33% of measurement respectively). In particular, both CGF and aMDRD grossly overestimated renal function (mean bias 18.3 and 15.8 ml/min respectively, p<0.001) in CF patients with reduced creatinine clearance (<80 ml/min). CGF, aMDRD and other formulae cannot be used to reliably assess renal function in CF patients, since they will fail to detect those with renal impairment. Some form of carefully supervised direct measurement is still required.