Respiratory Rates Derived From Arterial Blood Pressure Waveforms in Telemetered Dogs.

The objective of this study was to extract low frequency respiratory "artifacts" from a standard arterial blood pressure (ABP) waveform to simultaneously derive reliable breathing rates (BR). Arterial blood pressure derived BR values were characterized against respiratory rates simultaneously obtained from the Respiratory Inductive Plethysmography (RIP) system (EMKA). Reference compounds were introduced to evaluate responsiveness of the derived measures to respiratory depressants and stimulants.

Translational assessment of cardiac contractility by echocardiography in the telemetered rat.

Introduction: Cardiac contractility was evaluated using standard inotropic agents in rats. We compared indices of cardiac contractility, i.e.

Climate change, extinction risks, and reproduction of terrestrial vertebrates.

This review includes a broad, but superficial, summary of our understanding about current and future climate changes, the predictions about how these changes will likely affect the risks of extinction of organisms, and how current climate changes are already affecting reproduction in terrestrial vertebrates. Many organisms have become extinct in the last century, but habitat destruction, disease and man-made factors other than climate change have been implicated as the causal factor in almost all of these. Reproduction is certain to be negatively impacted in all vertebrate groups for a variety of reasons, such as direct thermal and hydric effects on mortality of embryos, mismatches between optimal availability of food supplies, frequently determined by temperature, and reproductive capacities, sometimes determined by rigid factors such as photoperiod, and disappearance of appropriate foraging opportunities, such as melting sea ice.

Effects of temperature and hydric environment on survival of the Panamanian Golden Frog infected with a pathogenic chytrid fungus.

Considerable controversy exists concerning whether or not climate changes (particularly global warming) are causing outbreaks of a lethal amphibian pathogen, the chytrid fungus Batrachochytrium dendrobatidis (Longcore, Pessier & D.K. Nichols 1999).

Amphibian chytridiomycosis.

Amphibian chytridiomycosis is a fungal disease caused by the chytrid fungus Batrachochytrium dendrobatidis. It is arguably the most significant recorded infectious disease of any vertebrate class. The disease is reducing amphibian biodiversity across most continents and regions of the world, affecting the resilience of surviving populations and driving multiple species to extinction.

Stability and permanence in gender- and stage-structured models for the boreal toad.

The boreal toad Bufo boreas boreas, once common in the western USA, is listed as an endangered species in Colorado and New Mexico, and protected in Wyoming. Populations have dramatically declined due to the presence of the fungal pathogen Batrachochytrium dendrobatidis (Bd). A gender- and stage-structured model for the boreal toad is formulated which depends on its life cycle and breeding strategies.

The impacts of climate change on the annual cycles of birds.

Organisms living today are descended from ancestors that experienced considerable climate change in the past. However, they are currently presented with many new, man-made challenges, including rapid climate change. Migration and reproduction of many avian species are controlled by endogenous mechanisms that have been under intense selection over time to ensure that arrival to and departure from breeding grounds is synchronized with moderate temperatures, peak food availability and availability of nesting sites.

Immune defenses of Xenopus laevis against Batrachochytrium dendrobatidis.

Amphibian populations are declining at an unprecedented rate worldwide. A number of declines have been linked to a pathogenic skin fungus, Batrachochytrium dendrobatidis. Although amphibians have robust immune defenses, many species seem to be very susceptible to infection by this fungus and to development of the lethal disease called chytridiomycosis.

Predicted disease susceptibility in a Panamanian amphibian assemblage based on skin peptide defenses.

Chytridiomycosis is an emerging infectious disease of amphibians caused by a chytrid fungus, Batrachochytrium dendrobatidis. This panzootic does not equally affect all amphibian species within an assemblage; some populations decline, others persist. Little is known about the factors that affect disease resistance.

Emerging infectious disease and the loss of biodiversity in a Neotropical amphibian community.

Pathogens rarely cause extinctions of host species, and there are few examples of a pathogen changing species richness and diversity of an ecological community by causing local extinctions across a wide range of species. We report the link between the rapid appearance of a pathogenic chytrid fungus Batrachochytrium dendrobatidis in an amphibian community at El Copé, Panama, and subsequent mass mortality and loss of amphibian biodiversity across eight families of frogs and salamanders. We describe an outbreak of chytridiomycosis in Panama and argue that this infectious disease has played an important role in amphibian population declines.

Population trends associated with skin peptide defenses against chytridiomycosis in Australian frogs.

Many species of amphibians in the wet tropics of Australia have experienced population declines linked with the emergence of a skin-invasive chytrid fungus, Batrachochytrium dendrobatidis. An innate defense, antimicrobial peptides produced by granular glands in the skin, may protect some species from disease. Here we present evidence that supports this hypothesis.

How physiological methods and concepts can be useful in conservation biology.

The single and synergistic effects of man-made changes to the environment, such as habitat destruction, climate change, introduction of novel, long-lived chemicals into the environment, transport of exotic species and pathogens into new geographical areas, and other factors are predicted to cause widespread population declines and species extinctions of plants and animals in this century. From its inception, physiology has dealt with organismal capacities to deal with environmental change. This essay argues that physiologists, their methods and concepts can make more substantial contributions to Conservation Biology than they have to date.

Effects of ultraviolet radiation on toad early life stages.

Background: Exposure to harmful levels of ultraviolet-B radiation (UVB), a component of solar radiation, has been suggested as a potential cause of amphibian declines.

Methods: We measured solar radiation (UVB, ultraviolet-A, and visible) wavebands in breeding ponds of Bufo boreas (boreal toad, a montane species that has undergone severe population declines) and Bufo woodhousii (Woodhouse's toad, a plains toad that has not experienced declines)and examined tolerances of these species to simulated solar UVB exposures in the laboratory.

Results: We found larvae of both species to be tolerant of simulated solar UVB in excess of solar UVB levels observed in their breeding ponds.

Activities of temporin family peptides against the chytrid fungus (Batrachochytrium dendrobatidis) associated with global amphibian declines.

Temporin A and structurally related peptides produced in amphibian dermal granular glands and in wasp venom were tested for growth inhibition of Batrachochytrium dendrobatidis, a pathogen associated with global amphibian declines. Two natural amphibian temporins, a wasp temporin, and six synthetic analogs effectively inhibited growth. Differences in potency due to amino acid substitution suggest that ability to penetrate membranes and form an alpha-helical structure is important for their effectiveness against this pathogen.

Activity of antimicrobial skin peptides from ranid frogs against Batrachochytrium dendrobatidis, the chytrid fungus associated with global amphibian declines.

Accumulating evidence suggests that a chytrid fungus, Batrachochytrium dendrobatidis, is responsible for recent declines in amphibian populations in Australia, Central America, Europe, and North America. Because the chytrid infects the keratinized epithelium of the skin, we investigated the possible role of antimicrobial peptides produced in the skin as inhibitors of infection and growth. We show here that 10 peptides representing eight families of peptides derived from North American ranid frogs can effectively inhibit growth of this chytrid.

Antimicrobial peptide defenses against pathogens associated with global amphibian declines.

Global declines of amphibian populations are a source of great concern. Several pathogens that can infect the skin have been implicated in the declines. The pathogen most frequently associated with recent die-offs is a chytrid fungus, Batrachochytrium dendrobatidis.

Aerobic and anaerobic energy expenditure during rest and activity in montane Bufo b. boreas and Rana pipiens.

The relations of standard and active aerobic and anaerobic metabolism and heart rate to body temperature (T ) were measured in montane groups of Bufo b. boreas and Rana pipiens maintained under field conditions. These amphibians experience daily variation of T over 30°C and 23°C, respectively (Carey, 1978).

Effect of constant and fluctuating temperatures on resting and active oxygen consumption of toads, Bufo boreas.

The relations of standard and active rates of oxygen consumption to body temperature (T) were tested in montane Bufo b. boreas and lowland Bufo boreas halophilus acclimated to constant T of 10, 20, or 30° C or to a fluctuating cycle of 5-30° C. Standard metabolic rates (SMR) of boreas acclimated to 30° C and halophilus acclimated to 10° C show pronounced regions of thermal independence but all other standard and active metabolic rates of groups acclimated to other thermal regimes are thermally sensitive.

Factors affecting body temperatures of toads.

Factors influencing levels and rates of variation of body temperature (T ) in montane Bufo boreas boreas and in lowland Bufo boreas halophilus were investigated as an initial step toward understanding the role of natural thermal variation in the physiology and energetics of these ectothermic animals. Body temperatures of boreas can vary 25-30° C over 24-h periods. Such variation is primarily due to both nocturnal and diurnal activity and the physical characteristics of the montane environment.