Cerebral and Ocular Ochroconiasis in 2 Elegant Crested Tinamou (Eudromia elegans) Chicks.

Two elegant crested tinamou chicks (Eudromia elegans), aged 27 and 50 days, respectively, died following acute onset of weakness and neurologic disease. Microscopically, the cerebral hemispheres of both chicks and the optic lobes of 1 chick contained multifocal granulomatous and heterophilic inflammation and necrosis with intralesional pigmented, thin-walled, fungal hyphae. In 1 chick, hyphae extended along the optic nerve into the globe and were associated with severe granulomatous and heterophilic inflammation of the choroid, retina, pecten, and vitreous. In both chicks, polymerase chain reaction amplification of the fungal 28S large subunit ribosomal RNA was positive with 99% sequence identity to Ochroconis gallopava. While a well-characterized fungal infection of domestic poultry, ochroconiasis has rarely been reported in exotic avian species, and this is the first histologic characterization of ocular ochroconiasis in any avian species.

Invaders of pollination networks in the Galapagos Islands: emergence of novel communities.

The unique biodiversity of most oceanic archipelagos is currently threatened by the introduction of alien species that can displace native biota, disrupt native ecological interactions, and profoundly affect community structure and stability. We investigated the threat of aliens on pollination networks in the species-rich lowlands of five Galápagos Islands. Twenty per cent of all species (60 plants and 220 pollinators) in the pooled network were aliens, being involved in 38 per cent of the interactions. Most aliens were insects, especially dipterans (36%), hymenopterans (30%) and lepidopterans (14%). These alien insects had more links than either endemic pollinators or non-endemic natives, some even acting as island hubs. Aliens linked mostly to generalized species, increasing nestedness and thus network stability. Moreover, they infiltrated all seven connected modules (determined by geographical and phylogenetic constraints) of the overall network, representing around 30 per cent of species in two of them. An astonishingly high proportion (38%) of connectors, which enhance network cohesiveness, was also alien. Results indicate that the structure of these emergent novel communities might become more resistant to certain type of disturbances (e.g. species loss), while being more vulnerable to others (e.g. spread of a disease). Such notable changes in network structure as invasions progress are expected to have important consequences for native biodiversity maintenance.

Pollination patterns and plant breeding systems in the Galapagos: a review.

BACKGROUND: Despite the importance of the Galápagos Islands for the development of central concepts in ecology and evolution, the understanding of many ecological processes in this archipelago is still very basic. One such process is pollination, which provides an important service to both plants and their pollinators. The rather modest level of knowledge on this subject has so far limited our predictive power on the consequences of the increasing threat of introduced plants and pollinators to this unique archipelago. SCOPE: As a first step toward building a unified view of the state of pollination in the Galápagos, a thorough literature search was conducted on the breeding systems of the archipelago's flora and compiled all documented flower-visitor interactions. Based on 38 studies from the last 100 years, we retrieved 329 unique interactions between 123 flowering plant species (50 endemics, 39 non-endemic natives, 26 introduced and eight of unknown origin) from 41 families and 120 animal species from 13 orders. We discuss the emergent patterns and identify promising research avenues in the field. CONCLUSIONS: Although breeding systems are known for <20 % of the flora, most species in our database were self-compatible. Moreover, the incidence of autogamy among endemics, non-endemic natives and alien species did not differ significantly, being high in all groups, which suggests that a poor pollinator fauna does not represent a constraint to the integration of new plant species into the native communities. Most interactions detected (approx. 90 %) come from a single island (most of them from Santa Cruz). Hymenopterans (mainly the endemic carpenter bee Xylocopa darwinii and ants), followed by lepidopterans, were the most important flower visitors. Dipterans were much more important flower visitors in the humid zone than in the dry zone. Bird and lizard pollination has been occasionally reported in the dry zone. Strong biases were detected in the sampling effort dedicated to different islands, time of day, focal plants and functional groups of visitors. Thus, the existing patterns need to be confronted with new and less biased data. The implementation of a community-level approach could greatly increase our understanding of pollination on the islands and our ability to predict the consequences of plant invasions for the natural ecosystems of the Galápagos.

Origin and evolution of endemic Galápagos Varronia species (Cordiaceae).

Four endemic Varronia species (Cordiaceae) occupy the Galápagos archipelago. Three comprise the V. leucophlyctis complex (V. anderssonii, V. leucophlyctis, V. scouleri), whose species' limits are not well defined but that is morphologically distinct from the fourth endemic species, V. revoluta. Sequence data from the nuclear rDNA ITS region and the cpDNA ndhF gene were gathered from 49 accessions of Varronia from five Galápagos islands in order to test the evolutionary relationships of endemic Varronia species, determine the number of immigration events to the islands and estimate their age of origin. All endemic species nest within the clade of species belonging to Varronia, which is an entirely American genus. We find little evidence of phylogenetic structuring of the V. leucophlyctis complex but divergent phylogenetic signals from nuclear and chloroplast genomes regarding its relationship to V. revoluta. Results are consistent with a hybridization event involving ancestral Galapagean lineages, with chloroplast and nuclear data suggesting one or two dispersal events from the Americas to the Galápagos, respectively. Fossil-based divergence time estimates indicate endemic species diverged from American continental species as early as 4.5 Myr ago and radiated 1.12 Myr, which coincides with ages of exposed and subsided Galápagos islands.

Energetics of muscle contraction: the whole is less than the sum of its parts.

Understanding muscle energetics is a problem in optimizing supply of ATP to the demands of ATPases. The complexity of reactions and their fluxes to achieve this balance is greatly reduced by recognizing constraints imposed by the integration of common metabolites at fixed stoichiometry among modular units. ATPase is driven externally. Oxidative phosphorylation and glycogenolysis are the suppliers. We focus on their regulation which involves different controls, but reduces to two principles that enable facile experimental analysis of the supply and demand fluxes. The ratio of concentration of phosphocreatine (PCr) to ATP, not their individual values, sets the range of achievable concentrations of ADP in resting and active muscle (at fixed pH) in different cell types. This principle defines the fraction of available flux of oxidative phosphorylation utilized (at fixed enzyme activities). Then the kinetics of PCr recovery defines the kinetics of oxygen supply and substrate utilization. The second principle is the constancy of PCr and H(+) (lactate) production by glycogenolysis due to the coupling of ATPase and glycolysis. This principle enables glycogenolytic flux to be measured from intracellular proton loads. Further simplification occurs because the magnitude of the interacting fluxes and metabolite concentrations are specified within narrow limits when both the resting and active fluxes are quantified. Thus there is a small set of rules for assessing and understanding the thermodynamics and kinetics of muscle energetics.

Limits to sustainable muscle performance: interaction between glycolysis and oxidative phosphorylation.

This paper proposes a mechanism responsible for setting the sustainable level of muscle performance. Our contentions are that the sustainable work rate is determined (i) at the muscle level, (ii) by the ability to maintain ATP supply and (iii) by the products of glycolysis that may inhibit the signal for oxidative phosphorylation. We argue below that no single factor 'limits' sustainable performance, but rather that the flux through and the interaction between glycolysis and oxidative phosphorylation set the level of sustainable ATP supply. This argument is based on magnetic resonance spectroscopy measurements of the sources and sinks for energy in vivo in human muscle and rattlesnake tailshaker muscle during sustained contractions. These measurements show that glycolysis provides between 20% (human muscle) and 40% (tailshaker muscle) of the ATP supply during sustained contractions in these muscles. We cite evidence showing that this high glycolytic flux does not reflect an O(2) limitation or mitochondria operating at their capacity. Instead, this flux reflects a pathway independent of oxidative phosphorylation for ATP supply during aerobic exercise. The consequence of this high glycolytic flux is accumulation of H(+), which we argue inhibits the rise in the signal activating oxidative phosphorylation, thereby restricting oxidative ATP supply to below the oxidative capacity. Thus, both glycolysis and oxidative phosphorylation play important roles in setting the highest steady-state ATP synthesis flux and thereby determine the sustainable level of work by exercising muscle.

Human aerobic performance: too much ado about limits to V(O(2)).

Human endurance performance is often evaluated on the basis of the maximal rate of oxygen uptake during exercise (V(O(2)max)). Methods for overcoming limits to V(O(2)max) are touted as means for increasing athletic endurance performance. Here, we argue that the respiratory system is well designed for delivering O(2) to meet O(2) demands and that no single factor is rate-determining for O(2) uptake. We show that V(O(2)max) can vary 5000-fold among mammals, while any limitation to O(2) delivery by a single component of the respiratory system affects V(O(2)max) by 10% or less. Attempts to increase O(2) delivery by enhancing one step in the respiratory system are shown to have little effect. Blood doping, hyperoxia and O(2) supplementation of high-altitude natives all raise O(2) availability substantially to the working muscles, but these treatments increase V(O(2)max) only minimally. Finally, we argue that O(2) uptake is only one of a number of properties important to human aerobic performance.

Coping strategies used in residential hospice settings: findings from a national study.

The purpose of this study was to explore professional caregivers' coping strategies for dealing with the deaths of patients in residential hospices in the United States. Using the Guide to the Nation's Hospices, 1996-97, purely residential hospices were identified and invited to participate in the study. Employees at each residential hospice were asked to complete the Ways of Coping Questionnaire. Results indicated that positive reappraisal coping was the most frequently used coping strategy. Employees dissatisfied with the coping experience reported greater use of confrontive coping, escape-avoidance coping, and accepting responsibility strategies. The findings suggest that in-service training related to coping strategies and environmental interventions may help in strengthening the coping responses of residential hospice staff.

Large energetic adaptations of elderly muscle to resistance and endurance training.

This study determined the cellular energetic and structural adaptations of elderly muscle to exercise training. Forty male and female subjects (69.2 +/- 0.6 yr) were assigned to a control group or 6 mo of endurance (ET) or resistance training (RT). We used magnetic resonance spectroscopy and imaging to characterize energetic properties and size of the quadriceps femoris muscle. The phosphocreatine and pH changes during exercise yielded the muscle oxidative properties, glycolytic ATP synthesis, and contractile ATP demand. Muscle biopsies taken from the same site as the magnetic resonance measurements were used to determine myosin heavy chain isoforms, metabolite concentrations, and mitochondrial volume densities. The ET group showed changes in all energetic pathways: oxidative capacity (+31%), contractile ATP demand (-21%), and glycolytic ATP supply (-56%). The RT group had a large increase in oxidative capacity (57%). Only the RT group exhibited change in structural properties: a rise in mitochondrial volume density (31%) and muscle size (10%). These results demonstrate large energetic, but smaller structural, adaptations by elderly muscle with exercise training. The rise in oxidative properties with both ET and RT suggests that the aerobic pathway is particularly sensitive to exercise training in elderly muscle. Thus elderly muscle remains adaptable to chronic exercise, with large energetic changes accompanying both ET and RT.

Evaluation of orthostatic blood pressure testing as a discharge criterion from PACU after spinal anesthesia.

Discharge readiness from a Phase I PACU after spinal anesthesia is frequently determined by recovery of sensory/motor function. However, no data exist indicating that recovery of sensory/motor function adequately predicts hemodynamic stability after spinal anesthesia. The conservative practice of waiting until the sensory/motor effects of spinal anesthesia have completely worn off often requires patients to remain in PACU for prolonged periods of time. The purpose of this study was to determine the safety and efficacy of using orthostatic blood pressure (BP) testing as a discharge criterion from PACU after spinal anesthesia. This study used a prospective, descriptive design to measure changes in mean arterial pressure (MAP) during orthostatic BP testing at 30-minute intervals after admission to the PACU following spinal anesthesia. A convenience sample of 121 patients admitted through the Same Day Surgery (SDS) unit was used. Results show that orthostatic BP criterion was safe and effective as an alternative to sensory/motor criteria in assessing hemodynamic stability and reducing the amount of time patients spend in the PACU after spinal anesthesia. This is a U.S. government work. There are no restrictions on its use.

Shaking up glycolysis: Sustained, high lactate flux during aerobic rattling.

Substantial ATP supply by glycolysis is thought to reflect cellular anoxia in vertebrate muscle. An alternative hypothesis is that the lactate generated during contraction reflects sustained glycolytic ATP supply under well-oxygenated conditions. We distinguished these hypotheses by comparing intracellular glycolysis during anoxia to lactate efflux from muscle during sustained, aerobic contractions. We examined the tailshaker muscle of the rattlesnake because of its uniform cell properties, exclusive blood circulation, and ability to sustain rattling for prolonged periods. Here we show that glycolysis is independent of the O(2) level and supplies one-third of the high ATP demands of sustained tailshaking. Fatigue is avoided by rapid H(+) and lactate efflux resulting from blood flow rates that are among the highest reported for vertebrate muscle. These results reject the hypothesis that glycolysis necessarily reflects cellular anoxia. Instead, they demonstrate that glycolysis can provide a high and sustainable supply of ATP along with oxidative phosphorylation without muscle fatigue.

Assessment of hand-arm vibration syndrome in a northern Ontario base metal mine.

The objective of this study was to determine the prevalence of hand-arm vibration syndrome (HAVS) in 617 workers at a base metal mine in northern Ontario. Workers who were employed at the mine between the years 1989 and 1994 and who continued to live within a 100 km radius of the mine were sent a self-reported questionnaire to identify individuals with possible vibration-induced symptoms in their upper extremities. Of the 162 workers who attended the medical examination, 50% were diagnosed with HAVS, 26% had other diagnoses with some workers having multiple afflictions e.g., both HAVS and carpal tunnel syndrome (CTS). No vibration-induced symptoms were reported in 35% of the workers who were clinically normal. The study was designed to educate, advise, and to make recommendations on the prevention of HAVS. Ongoing commitments to technological improvements, mandatory and regular rest periods, and continuing educational sessions on the syndrome should help to reduce the prevalence of this disease.

A knowledge-based patient assessment system: conceptual and technical design.

This paper describes the design of an inpatient patient assessment application that captures nursing assessment data using a wireless laptop computer. The primary aim of this system is to capture structured information for facilitating decision support and quality monitoring. The system also aims to improve efficiency of recording patient assessments, reduce costs, and improve discharge planning and early identification of patient learning needs. Object-oriented methods were used to elicit functional requirements and to model the proposed system. A tools-based development approach is being used to facilitate rapid development and easy modification of assessment items and rules for decision support. Criteria for evaluation include perceived utility by clinician users, validity of decision support rules, time spent recording assessments, and perceived utility of aggregate reports for quality monitoring.

Oxidative capacity and ageing in human muscle.

This study determined the decline in oxidative capacity per volume of human vastus lateralis muscle between nine adult (mean age 38.8 years) and 40 elderly (mean age 68.8 years) human subjects (age range 25-80 years). We based our oxidative capacity estimates on the kinetics of changes in creatine phosphate content ([PCr]) during recovery from exercise as measured by (31)P magnetic resonance (MR) spectroscopy. A matched muscle biopsy sample permitted determination of mitochondrial volume density and the contribution of the loss of mitochondrial content to the decline in oxidative capacity with age. The maximal oxidative phosphorylation rate or oxidative capacity was estimated from the PCr recovery rate constant (k(PCr)) and the [PCr] in accordance with a simple electrical circuit model of mitochondrial respiratory control. Oxidative capacity was 50 % lower in the elderly vs. the adult group (0.61 +/- 0.04 vs. 1.16 +/- 0.147 mM ATP s(-1)). Mitochondrial volume density was significantly lower in elderly compared with adult muscle (2.9 +/- 0.15 vs. 3.6 +/- 0.11 %). In addition, the oxidative capacity per mitochondrial volume (0.22 +/- 0.042 vs. 0.32 +/- 0.015 mM ATP (s %)(-1)) was reduced in elderly vs. adult subjects. This study showed that elderly subjects had nearly 50 % lower oxidative capacity per volume of muscle than adult subjects. The cellular basis of this drop was a reduction in mitochondrial content, as well as a lower oxidative capacity of the mitochondria with age.

Ageing, muscle properties and maximal O(2) uptake rate in humans.

This paper asks how the decline in maximal O(2) uptake rate (VO(2),max) with age is related to the properties of a key muscle group involved in physical activity - the quadriceps muscles. Maximal oxygen consumption on a cycle ergometer was examined in nine adult (mean age 38.8 years) and 39 elderly subjects (mean age 68.8 years) and compared with the oxidative capacity and volume of the quadriceps. VO(2),max declined with age between 25 and 80 years and the increment in oxygen consumption from unloaded cycling to VO(2),max (delta VO(2)) in the elderly was 45 % of the adult value. The cross-sectional areas of the primary muscles involved in cycling - the hamstrings, gluteus maximus and quadriceps - were all lower in the elderly group. The quadriceps volume was reduced in the elderly to 67 % of the adult value. Oxidative capacity per quadriceps volume was reduced to 53 % of the adult value. The product of oxidative capacity and muscle volume - the quadriceps oxidative capacity - was 36 % of the adult value in the elderly. Quadriceps oxidative capacity was linearly correlated with delta VO(2) among the subjects with the slope indicating that the quadriceps represented 36 % of the VO(2) increase during cycling. The decline in quadriceps oxidative capacity with age resulted from reductions in both muscle volume and oxidative capacity per volume in the elderly and appears to be an important determinant of the age-related reduction in delta VO(2) and VO(2),max found in this study.

Deciphering the mysteries of myoglobin in striated muscle.

Myoglobin (Mb) is a large protein that reversibly binds oxygen in the muscle cell and is thought to be critical for O2 supply to the mitochondria during exercise. The role of Mb in aerobic function is evaluated based on the physical properties of Mb as an O2 carrier and experimental evidence of Mb function in vivo. This role depends on the reversible binding of O2 by Mb depending on PO2, which results in: (1) storage of O2; (2) buffering of PO2 in the cell to prevent mitochondrial anoxia; and (3) parallel diffusion of O2 (so-called, 'facilitated diffusion'). The storage role is well established in diving mammals and buffering of cell PO2 above anoxic levels is shown here by in vivo magnetic resonance spectroscopy (MRS). However, the quantitative role of Mb in 'facilitated' or parallel diffusion of O2 is controversial. Evidence in support of this role is from MRS analyses, which reveal rapid Mb desaturation with exercise, and from the proportionality of Mb content of a muscle to the O2 diffusion limitation. Recent experiments with myoglobin knockout mice demonstrating high levels of aerobic function in normal and myoglobin-free mice argue against a link between Mb and oxidative phosphorylation. Thus, the current evidence supports the role of Mb in the physical diffusion of O2; however, the unimpaired aerobic function of Mb knockout mice indicates that this role may not be critical to O2 supply in active muscle.

Heparin-induced thrombocytopenia (HIT).

Heparin-induced thrombocytopenia (HIT) is a complication of heparin therapy that can cause arterial and venous thrombosis. Because heparin is widely used in the medical-surgical population, nurses must be aware of this clinically significant drug reaction. The pathophysiology, clinical presentation, diagnosis, and treatment of HIT are reviewed.