New Evidence for the Diversity of Mechanisms and Protonated Schiff Bases Formed in the Non-Enzymatic Covalent Protein Modification (NECPM) of HbA by the Hydrate and Aldehydic Forms of Acetaldehyde and Glyceraldehyde.

Acetaldehyde is a physiological species existing in blood. Glyceraldehyde is a commonly-used surrogate for glucose in studies of nonenzymatic glycation. Both species exist in dynamic equilibrium between two forms, an aldehyde and a hydrate.

Echocardiography and electrocardiography reveal differences in cardiac hemodynamics, electrical characteristics, and thermal sensitivity between northern pike, rainbow trout, and white sturgeon.

Doppler and B-mode ultrasonography and electrocardiography (ECG) were used to determine cardiac hemodynamics and electrical characteristics in 12°C-acclimated and metomidate-anesthetized northern pike, rainbow trout and white sturgeon (7-9 per species) at 12°C and 20°C, and at a comparable heart rate (f , ~60 beats/min). Despite similar relative ventricle masses and cardiac output (Q), interspecific differences were observed at 12°C in f , ventricular filling and ejection, stroke volume, the duration ECG intervals, and cardiac valve cross-sectional areas. Vis-a-fronte filling of the atrium due to ventricular contraction was observed in all species.

Insights into the Progression of Labile Hb A to Stable Hb A a Mechanistic Assessment of 2,3-Bisphosphoglycerate Facilitation of the Slow Nonenzymatic Glycation Process.

Nonenzymatic glycation (NEG) of human hemoglobin (Hb A) consists of initial non covalent, reversible steps involving glucose and amino acid residues, which may also involve effector reagent(s) in the formation of labile Hb A (the conjugate acid of the Schiff base). Labile Hb A can then undergo slow, largely irreversible, formation of stable Hb A (the Amadori product). Stable Hb A is measured to assess diabetic progression after labile Hb A removal.

Is the teleost heart oxygen limited? - Insights using "hyperoxic" incubations of contracting cardiac tissue from rainbow trout.

Considerable effort has been devoted to understanding the negative effects of reduced PO on cardiac function. Much less is known about the impacts of elevated PO (hyperoxia) on cardiac performance and energetics, especially in fishes. The fish heart is of particular interest because cardiac dependence on oxygen is extremely variable between species and the early evolution of fish occurred when atmospheric PO was higher than current conditions.

Potential roles of inorganic phosphate on the progression of initially bound glucopyranose toward the nonenzymatic glycation of human hemoglobin: mechanistic diversity and impacts on site selectivity.

Nonenzymatic glycation (NEG) begins with the non-covalent binding of a glucopyranose to a protein. The bound glucopyranose must then undergo structural modification to generate a bound electrophile that can reversibly form a Schiff base, which can then lead to Amadori intermediates, and ultimately to glycated proteins. Inorganic phosphate (Pi) is known to accelerate the glycation of human hemoglobin (HbA), although the specific mechanism(s) of Pi as an effector reagent have not been determined.

A Perspective on Reagent Diversity and Non-covalent Binding of Reactive Carbonyl Species (RCS) and Effector Reagents in Non-enzymatic Glycation (NEG): Mechanistic Considerations and Implications for Future Research.

This perspective focuses on illustrating the underappreciated connections between reactive carbonyl species (RCS), initial binding in the nonenzymatic glycation (NEG) process, and nonenzymatic covalent protein modification (here termed NECPM). While glucose is the central species involved in NEG, recent studies indicate that the initially-bound glucose species in the NEG of human hemoglobin (HbA) and human serum albumin (HSA) are non-RCS ring-closed isomers. The ring-opened glucose, an RCS structure that reacts in the NEG process, is most likely generated from previously-bound ring-closed isomers undergoing concerted acid/base reactions while bound to protein.

Mass Transport: Circulatory System with Emphasis on Nonendothermic Species.

Mass transport can be generally defined as movement of material matter. The circulatory system then is a biological example given its role in the movement in transporting gases, nutrients, wastes, and chemical signals. Comparative physiology has a long history of providing new insights and advancing our understanding of circulatory mass transport across a wide array of circulatory systems.

Dichloroacetate selectively improves cardiac function and metabolism in female and male rainbow trout.

Cardiac tissue from female rainbow trout demonstrates a sex-specific preference for exogenous glucose and glycolysis, impaired Ca(2+) handling, and a greater tolerance for hypoxia and reoxygenation than cardiac tissue from male rainbow trout. We tested the hypothesis that dichloroacetate (DCA), an activator of pyruvate dehydrogenase, enhances cardiac energy metabolism and Ca(2+) handling in female preparations and provide cardioprotection for hypoxic male tissue. Ventricle strips from sexually immature fish with very low (male) and nondetectable (female) plasma sex steroids were electrically paced in oxygenated or hypoxic Ringer solution with or without 1 mM DCA.

Temperature and sex dependent effects on cardiac mitochondrial metabolism in Atlantic cod (Gadus morhua L.).

To test the hypothesis that impaired mitochondrial respiration limits cardiac performance at warm temperatures, and examine if any effect(s) are sex-related, the consequences of high temperature on cardiac mitochondrial oxidative function were examined in 10°C acclimated, sexually immature, male and female Atlantic cod. Active (State 3) and uncoupled (States 2 and 4) respiration were measured in isolated ventricular mitochondria at 10, 16, 20, and 24°C using saturating concentrations of malate and pyruvate, but at a submaximal (physiological) level of ADP (200µM). In addition, citrate synthase (CS) activity was measured at these temperatures, and mitochondrial respiration and the efficiency of oxidative phosphorylation (P:O ratio) were determined at [ADP] ranging from 25-200µM at 10 and 20°C.

Differential effects of temperature and glucose on glycogenolytic enzymes in tissues of rainbow trout (Oncorhynchus mykiss).

The pathways and regulatory mechanisms of glycogenolysis remain relatively unexplored in non-mammalian vertebrates, especially poikilotherms. We studied the temperature sensitivity and inhibition of glycogenolytic enzymes in liver, ventricle, and white muscle of rainbow trout acclimated to 14 °C. Glycogen phosphorylase (GP) and acid α-glucosidase (GAA) activities were measured in homogenates of tissues at physiological temperatures (4, 14, and 24 °C), and in the presence of allosteric inhibitor, glucose.

The initial noncovalent binding of glucose to human hemoglobin in nonenzymatic glycation.

Mechanisms for nonenzymatic protein glycation have been extensively studied albeit with an emphasis at the later stages that gives rise to advanced glycation end products. No detailed investigation of the initial, noncovalent binding of d-glucose to human hemoglobin A (HbA) exists in the literature. Although anionic molecules 2,3-bisphosphoglycerate (BPG), inorganic phosphate (Pi) and HCO3(-) have been implicated in the latter stages of glycation, their involvement at the initial binding of glucose to HbA has not yet been assessed.

Increased ventricular stiffness and decreased cardiac function in Atlantic cod (Gadus morhua) at high temperatures.

We employed the work loop method to study the ability of ventricular and atrial trabeculae from Atlantic cod to sustain power production during repeated contractions at acclimation temperatures (10°C) and when acutely warmed (20°C). Oxygen tension (Po2) was lowered from 450 to 34% air saturation to augment the thermal stress. Preparations worked under conditions simulating either a large stroke volume (35 contractions/min rate, 8-12% muscle strain) or a high heart rate (70 contractions/min, 2-4% strain), with power initially equal under both conditions.

Limited effects of exogenous glucose during severe hypoxia and a lack of hypoxia-stimulated glucose uptake in isolated rainbow trout cardiac muscle.

We examined whether exogenous glucose affects contractile performance of electrically paced ventricle strips from rainbow trout under conditions known to alter cardiomyocyte performance, ion regulation and energy demands. Physiological levels of d-glucose did not influence twitch force development for aerobic preparations (1) paced at 0.5 or 1.

Glycated hemoglobin is not an accurate indicator of glycemia in rainbow trout.

Glycation occurs when glucose reacts non-enzymatically with proteins. This reaction depends upon time, ambient glucose concentration, and the molecular conformation of reactive amino acids. Little is known about protein glycation in fishes and the main objective of this study was to measure glycated hemoglobin (GHb) in rainbow trout, a glucose-intolerant species, under normoglycemic and hyperglycemic conditions.

Survey of parasites in threatened stocks of coho salmon (Oncorhynchus kisutch) in Oregon by examination of wet tissues and histology.

We are conducting studies on the impacts of parasites on Oregon coastal coho salmon (Oncorhynchus kistuch). An essential first step is documenting the geographic distribution of infections, which may be accomplished by using different methods for parasite detection. Thus, the objectives of the current study were to (1) identify parasite species infecting these stocks of coho salmon and document their prevalence, density, and geographic distribution; (2) assess the pathology of these infections; and (3) for the first time, determine the sensitivity and specificity of histology for detecting parasites compared with examining wet preparations for muscle and gill infections.

Carbohydrate energy reserves and effects of food deprivation in male and female rainbow trout.

We investigated the effects of nutritional state on carbohydrate, lipid, and protein stores in the heart, liver, and white skeletal muscle of male and female rainbow trout. For fed animals we also partitioned glycogen into fractions based on acid solubility. Fish (10-14 months-old, ~400-500 g) were held at 14 °C and either fed (1% of body weight, every other day) or deprived of food for 14 days.

Effects of Batrachochytrium dendrobatidis infection on ion concentrations in the boreal toad Anaxyrus (Bufo) boreas boreas.

Batrachochytrium dendrobatidis causes mortality in various amphibian species including the boreal toad Anaxyrus (Bufo) boreas boreas. The purpose of this study was to determine the physiological effects of this pathogen on experimentally infected boreal toads. Plasma osmolality, sodium, and potassium concentrations were analyzed to evaluate the differences between diseased and non-exposed animals.

WITHDRAWN: Profiles in Comparative Endocrinology: Carl B. Schreck Howard Bern Lecturer, Annual Meeting of Society of Integrative and Comparative Endocrinology, Seattle, January 5, 2010.

This article has been withdrawn at the request of the editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.

Dietary carbohydrate level affects transcription factor expression that regulates skeletal muscle myogenesis in rainbow trout.

Understanding the effects of dietary carbohydrates on transcription factors that regulate myogenesis provides insight into the role of nutrient sensing by satellite cells towards myocyte differentiation. We evaluated the influence of dietary carbohydrate level (0, 15, 25 or 35%) on the temporal mRNA expression patterns (4, 8 or 12 weeks) of transcription factors that regulate satellite cell myocyte addition (MA) in rainbow trout (Oncorhynchus mykiss), a vertebrate with indeterminate growth. Relative to the 0% carbohydrate (NC) diet, 15 (IC-15) and 25% (IC-25) carbohydrate containing diets significantly up-regulate MyoD and Myf5, but not Pax7, after 12 weeks of feeding.

Contribution of impaired myocardial insulin signaling to mitochondrial dysfunction and oxidative stress in the heart.

Background: Diabetes-associated cardiac dysfunction is associated with mitochondrial dysfunction and oxidative stress, which may contribute to left ventricular dysfunction. The contribution of altered myocardial insulin action, independent of associated changes in systemic metabolism, is incompletely understood. The present study tested the hypothesis that perinatal loss of insulin signaling in the heart impairs mitochondrial function.

Effect of starvation on transcriptomes of brain and liver in adult female zebrafish (Danio rerio).

We used microarray and quantitative real-time PCR (qRT-PCR) analyses in adult female zebrafish (Danio rerio) to identify metabolic pathways regulated by starvation in the liver and brain. The transcriptome of whole zebrafish brain showed little response to 21 days of starvation. Only agouti-related protein 1 (agrp1) significantly responded, with increased expression in brains of starved fish.

Sexual dimorphism in hepatic gene expression and the response to dietary carbohydrate manipulation in the zebrafish (Danio rerio).

In this study, we tested for the presence of sexual dimorphism in the hepatic transcriptome of the adult zebrafish and examined the effect of long term manipulation of dietary carbohydrate on gene expression in both sexes. Zebrafish were fed diets comprised of 0%, 15%, 25%, or 35% carbohydrate from the larval stage through sexual maturity, then sampled for hepatic tissue, growth, proximate body composition, and retention efficiencies. Using Affymetrix microarrays and qRT-PCR, we observed substantial sexual dimorphism in the hepatic transcriptome.

Cardiac hemodynamics of the rainbow trout (Oncorhynchus mykiss) using simultaneous Doppler echocardiography and electrocardiography.

Using Doppler echocardiography and electrocardiography, we characterized cardiac hemodynamics, timing, and electromechanical function, and examined the effects of ventricular hypertrophy on systolic function in anesthetized rainbow trout. Atrial filling (D(SA)), ventricular filling (D(AV)), and ventricular ejection (D(VB)) accounted for 40-77, 13-27, and 22-41% of the cardiac cycle, respectively. Ventricular ejection occurred entirely during atrial filling and ended by the time the QT interval was 80% (SD=9%) completed.

Fishing for an ECG: a student-directed electrocardiographic laboratory using rainbow trout.

Cardiac physiology is emphasized in many undergraduate physiology courses, but few nonmammalian vertebrate model systems exist that 1) can be studied fairly noninvasively, 2) are well suited for controlled experimentation, and 3) emphasize principles characteristic of the vertebrate heart. We have developed an inquiry-based undergraduate/graduate-level laboratory in cardiac physiology and electrocardiography using rainbow trout (Oncorhynchus mykiss Walbaum) and the BioPac MP30 data-acquisition system (other fish species and/or electrocardiographic recording devices can be substituted). This laboratory facilitates intensive study of vertebrate electrocardiograms (ECGs) under a variety of environmental and physiological perturbations and is ideal for use in multi-session, inquiry-based laboratory projects in animal physiology.

Sex differences in energy metabolism and performance of teleost cardiac tissue.

This study examined the effects of different oxygenation levels and substrate availability on cardiac performance, metabolism, and biochemistry in sexually immature male and female rainbow trout (Oncorhynchus mykiss). Ventricle strips were electrically paced (0.5 Hz, 14 degrees C) in hyperoxic or hypoxic Ringer solution.