Naphthenic acid fraction compounds reduce the reproductive success of wood frogs (Rana sylvatica) by affecting offspring viability.

Understanding the toxicity of organic compounds in oil sands process-affected water (OSPW) is necessary to inform the development of environmental guidelines related to wastewater management in Canada's oil sands region. In the present study, we investigated the effects of naphthenic acid fraction compounds (NAFCs), one of the most toxic components of OSPW, on mating behaviour, fertility, and offspring viability in the wood frog (Rana sylvatica). Wild adult wood frogs were exposed separately from the opposite sex to 0, 5, or 10 mg/L of OSPW-derived NAFCs for 24 h and then combined in outdoor lake water mesocosms containing the same NAFC concentrations (n = 2 males and 1 female per mesocosm, n = 3 mesocosms per treatment). Mating events were recorded for 48 h and egg masses were measured to determine adult fertility. NAFC exposure had no significant effect on mating behaviour (probability of amplexus and oviposition, amplexus and oviposition latency, total duration of amplexus and number of amplectic events) or fertility (fertilization success and clutch size). Tadpoles (50 individuals per mesocosm at hatching, and 15 individuals per mesocosm from 42 d post-hatch) were reared in the same mesocosms under chronic NAFC exposure until metamorphic climax (61-85 d after hatching). Offspring exposed to 10 mg/L NAFCs during development were less likely to survive and complete metamorphosis, grew at a reduced rate, and displayed more frequent morphological abnormalities. These abnormalities included limb anomalies at metamorphosis, described for the first time after NAFC exposure. The results of this study suggest that NAFCs reduce wood frog reproductive success through declines in offspring viability and therefore raise the concern that exposure to NAFCs during reproduction and development may affect the recruitment of native amphibian populations in the oil sands region.

Corrigendum to: Sex-specific differences in swimming, aerobic metabolism and recovery from exercise in adult coho salmon (Oncorhynchus kisutch) across ecologically relevant temperatures.

[This corrects the article DOI: 10.1093/conphys/coab016.].

Sex-specific differences in swimming, aerobic metabolism and recovery from exercise in adult coho salmon (Oncorhynchus kisutch) across ecologically relevant temperatures.

Adult female Pacific salmon can have higher migration mortality rates than males, particularly at warm temperatures. However, the mechanisms underlying this phenomenon remain a mystery. Given the importance of swimming energetics on fitness, we measured critical swim speed, swimming metabolism, cost of transport, aerobic scope (absolute and factorial) and exercise recovery in adult female and male coho salmon (Oncorhynchus kisutch) held for 2 days at 3 environmentally relevant temperatures (9°C, 14°C, 18°C) in fresh water. Critical swimming performance (U crit) was equivalent between sexes and maximal at 14°C. Absolute aerobic scope was sex- and temperature-independent, whereas factorial aerobic scope decreased with increasing temperature in both sexes. The full cost of recovery from exhaustive exercise (excess post-exercise oxygen consumption) was higher in males compared to females. Immediately following exhaustive exercise (i.e. 1 h), recovery was impaired at 18°C for both sexes. At an intermediate time scale (i.e. 5 h), recovery in males was compromised at 14°C and 18°C compared to females. Overall, swimming, aerobic metabolism, and recovery energetics do not appear to explain the phenomenon of increased mortality rates in female coho salmon. However, our results suggest that warming temperatures compromise recovery following exhaustive exercise in both male and female salmon, which may delay migration progression and could contribute to en route mortality.

Thyroid hormone regulation of thermal acclimation in ectotherms: Physiological mechanisms and ecoevolutionary implications.

The pathways that regulate adaptive thermal plasticity in ectothermic vertebrates have received little attention relative to those in birds and mammals. However, there is increasing evidence that thyroid hormone represents a critical regulator of thermal plasticity in both ectothermic and endothermic vertebrates. In this review, I summarize the evidence for thyroid hormone-mediated thermal compensation responses in ectothermic vertebrates, with specific focus on effects on the whole animal, skeletal muscle, and cardiac muscle. Interestingly, these effects can differ wildly between focal tissues and species. I move on to discuss what the role of thyroid hormone in ectotherm thermal plasticity can reveal about stressor interactions and central vs. peripheral levels of thyroid hormone regulation. Lastly, I focus on the conserved nature of thyroid hormone signaling in animal thermal responses, with specific reference to the ectotherm → endotherm spectrum. I use this framework to highlight research avenues that will further resolve the evolutionary trajectory of thyroid hormone actions across animals. I hope to emphasize what thyroid hormone-mediated cold acclimation in a 3 cm fish can contribute to ongoing debates surrounding the impacts of stressor interactions, the potential costs of plasticity, the evolution of endothermy, and the impacts of global change.

Reduced lactate dehydrogenase activity in the heart and suppressed sex hormone levels are associated with female-biased mortality during thermal stress in Pacific salmon.

Female-biased mortality has been repeatedly reported in Pacific salmon during their upriver migration in both field studies and laboratory holding experiments, especially in the presence of multiple environmental stressors, including thermal stress. Here, we used coho salmon (Oncorhynchus kisutch) to test whether females exposed to elevated water temperatures (18°C) (i) suppress circulating sex hormones (testosterone, 11-ketotestosterone and estradiol), owing to elevated cortisol levels, (ii) have higher activities of enzymes supporting anaerobic metabolism (e.g. lactate dehydrogenase, LDH), (iii) have lower activities of enzymes driving oxidative metabolism (e.g. citrate synthase, CS) in skeletal and cardiac muscle, and (iv) have more oxidative stress damage and reduced capacity for antioxidant defense [lower catalase (CAT) activity]. We found no evidence that a higher susceptibility to oxidative stress contributes to female-biased mortality at warm temperatures. We did, however, find that females had significantly lower cardiac LDH and that 18°C significantly reduced plasma levels of testosterone and estradiol, especially in females. We also found that relative gonad size was significantly lower in the 18°C treatment regardless of sex, whereas relative liver size was significantly lower in females held at 18°C. Further, relative spleen size was significantly elevated in the 18°C treatments across both sexes, with larger warm-induced increases in females. Our results suggest that males may better tolerate bouts of cardiac hypoxia at high temperature, and that thermal stress may also disrupt testosterone- and estradiol-mediated protein catabolism, and the immune response (larger spleens), in migratory female salmon.

Comparative biochemistry of cytochrome c oxidase in animals.

Cytochrome c oxidase (COX), the terminal enzyme of the electron transport system, is central to aerobic metabolism of animals. Many aspects of its structure and function are highly conserved, yet, paradoxically, it is also an important model for studying the evolution of the metabolic phenotype. In this review, part of a special issue honouring Peter Hochachka, we consider the biology of COX from the perspective of comparative and evolutionary biochemistry. The approach is to consider what is known about the enzyme in the context of conventional biochemistry, but focus on how evolutionary researchers have used this background to explore the role of the enzyme in biochemical adaptation of animals. In synthesizing the conventional and evolutionary biochemistry, we hope to identify synergies and future research opportunities. COX represents a rare opportunity for researchers to design studies that span the breadth of biology: molecular genetics, protein biochemistry, enzymology, metabolic physiology, organismal performance, evolutionary biology, and phylogeography.

Evolutionary affinity of billfishes (Xiphiidae and Istiophoridae) and flatfishes (Plueronectiformes): Independent and trans-subordinal origins of endothermy in teleost fishes.

Billfishes (Scombroidei) and tunas (Scombridae), both considered part of the suborder Scombroidei, have long been studied by biologists largely because of their remarkable physiological and anatomical muscular adaptations associated with regional endothermy and continuous swimming. These attributes, combined with analyses of other morphological and molecular data, have led to a general perception that tunas and billfishes are close relatives, though this hypothesis has been vigorously debated. Using Bayesian phylogenetic analysis of nine mitochondrial and three nuclear loci (>7000bp), we show that billfishes are only distantly related to tunas, but rather share strong evolutionary affinities with flatfishes (Pleuronectiformes) and jacks (Carangidae). This phylogenetic relationship is striking because of the marked variation in phenotype and niche across these trans-ordinal groups of fishes. Billfishes and flatfishes have each evolved radically divergent morphological and physiological features: elongated bills and extraocular heater organs in billfishes, and cranial asymmetry with complete eye migration during ontogenetic development in flatfishes. Despite this divergence, we identify synapomorphies consistent with the hypothesis of a common billfish/flatfish/jack ancestor.

Evolution of the nuclear-encoded cytochrome oxidase subunits in vertebrates.

Vertebrate mitochondrial cytochrome c oxidase (COX) possesses 10 nuclear-encoded subunits. Six subunits have paralogs in mammals, but the origins and distribution of isoforms among vertebrates have not been analyzed. We used Bayesian phylogenetic analysis to interpret the origins of each subunit, inferring the roles of gene and genome duplications. The paralogous ancestries of five genes were identical throughout the major vertebrate taxa: no paralogs of COX6c and COX7c, two paralogs of COX4 and COX6a, and three paralogs of COX7a. Two genes had an extra copy in teleosts (COX5a, COX5b), and three genes had additional copies in mammals (COX6b, COX7b, COX8). Focusing on early vertebrates, we examined structural divergence and explored transcriptional profiles across zebrafish tissues. Quantitative transcript profiles revealed dramatic differences in transcript abundance for different subunits. COX7b and COX4 transcripts were typically present at very low levels, whereas COX5a and COX8 were in vast excess in all tissues. For genes with paralogs, two general patterns emerged. For COX5a and COX8, there was ubiquitous expression of one paralog, with the other paralog in lower abundance in all tissues. COX4 and COX6a shared a distinct expression pattern, with one paralog dominant in brain and gills and the other in muscles. The isoform profiles in combination with phylogenetic analyses show that vertebrate COX isoform patterns are consistent with the hypothesis that early whole genome duplications in basal vertebrates governed the isoform repertoire in modern fish and tetrapods, though more recent lineage-specific gene/genome duplications also play a role in select subunits.

Esophageal cancer: results of an American College of Surgeons Patient Care Evaluation Study.

BACKGROUND: The last two decades have seen changes in the prevalence, histologic type, and management algorithms for patients with esophageal cancer. The purpose of this study was to evaluate the presentation, stage distribution, and treatment of patients with esophageal cancer using the National Cancer Database of the American College of Surgeons. STUDY DESIGN: Consecutively accessed patients (n = 5,044) with esophageal cancer from 828 hospitals during 1994 were evaluated in 1997 for case mix, diagnostic tests, and treatment modalities. RESULTS: The mean age of patients was 67.3 years with a male to female ratio of 3:1; non-Hispanic Caucasians made up most patients. Only 16.6% reported no tobacco use. Dysphagia (74%), weight loss (57.3%), gastrointestinal reflux (20.5%), odynophagia (16.6%), and dyspnea (12.1%) were the most common symptoms. Approximately 50% of patients had the tumor in the lower third of the esophagus. Of all patients, 51.6% had squamous cell histology and 41.9% had adenocarcinoma. Barrett's esophagus occurred in 777 patients, or 39% of those with adenocarcinoma. Of those patients that underwent surgery initially, pathology revealed stage I (13.3%), II (34.7%), III (35.7%), and IV (12.3%) disease. For patients with various stages of squamous cell cancer, radiation therapy plus chemotherapy were the most common treatment modalities (39.5%) compared with surgery plus adjuvant therapy (13.2%). For patients with adenocarcinoma, surgery plus adjuvant therapy were the most common treatment methods. Disease-specific overall survival at 1 year was 43%, ranging from 70% to 18% from stages I to IV. CONCLUSIONS: Cancer of the esophagus shows an increasing occurrence of adenocarcinoma in the lower third of the esophagus and is frequently associated with Barrett's esophagus. Choice of treatment was influenced by tumor histology and tumor site. Multimodality (neoadjuvant) therapy was the most common treatment method for patients with esophageal adenocarcinoma. The use of multimodality treatment did not appear to increase postoperative morbidity.

Obesity correlates with gastroesophageal reflux.

Thirty morbidly obese patients presenting for bariatric surgery were evaluated for symptomatic and objective evidence of gastroesophageal reflux. Sixteen patients had heartburn while 14 were asymptomatic. All underwent esophageal function testing; manometry was performed in all patients, pH monitoring in 28. Patients with esophageal pH < 4 for more than 5% of observed time weighed more than those with normal acid exposure, 165.2 vs 129.8 kg (P < 0.01), and had significantly higher body mass indices, 56.5 vs 48.3 kg/m2 (P < 0.05). Similarly, morbidly obese patients with abnormal reflux scores weighed significantly more and had greater body mass indices than patients with normal scores (P < 0.05). Lower esophageal sphincter pressure was higher in patients with normal esophageal acid exposure than in those with abnormal findings, 15.5 vs 12.5 mm Hg (P < 0.05). This study demonstrates a correlation between both weight and body mass index with gastroesophageal reflux.

The impact of nutritional status on the outcome of lung volume reduction surgery: a prospective study.

OBJECTIVES: To study the incidence and clinical significance of nutritional deficiencies in patients with emphysema undergoing lung volume reduction surgery (LVRS). DESIGN: Prospective observational study. SETTING: University-based teaching hospital. PATIENTS: Fifty-one consecutive patients with end-stage emphysema undergoing video-assisted thoracoscopic surgery for LVRS. INTERVENTIONS: All patients had their body mass index (BMI) and serum nutritional indexes (albumin, transferrin, total protein, cholesterol) measured preoperatively and postoperatively. Various clinical parameters were also compared between two groups. RESULTS: The BMI was normal in 24 patients (47%), and 27 patients (53%) had a below normal BMI. A preoperative analysis of the serum nutritional indexes revealed no clinically significant differences between the two groups, but postoperative levels were significantly lower in the low BMI group. Anthropometric measurements supported the designation of nutritional status by BMI. Clinically, 26% of the patients in the low BMI group required prolonged ventilatory support (> 24 h), compared to only 4% of the patients with a normal BMI. The hospital length of stay (LOS) also differed, averaging 15.9 days in the low BMI group, compared to an average of 11.8 days in the normal BMI group. CONCLUSION: Approximately 50% of patients undergoing LVRS for emphysema have a deficient nutritional status identifiable by BMI, but not by standard nutritional indexes. This impaired nutritional status is associated with increased morbidity following LVRS. We suggest that BMI is an accurate determinant of nutritional status in this patient population, and we speculate that preoperative repletion of nutritional deficiencies may decrease hospital morbidity, hospital LOS, and overall costs in the malnourished population undergoing LVRS.

Intraoperative lymphatic mapping for non-small cell lung cancer: the sentinel node technique.

BACKGROUND: The purpose of the study was to determine the accuracy and role of the sentinel node technique in patients with non-small cell lung cancer. METHODS: This study was carried out on 36 consecutive patients undergoing lung resection. Peritumoral tissue was infiltrated with isosulfan blue dye and the first lymph node to stain was identified as a sentinel node. Sensitivity and specificity of the sentinel node in predicting the status of other lymph node stations were determined. RESULTS: Seventeen patients had sentinel lymph nodes. In 9 of these 17 cases neither the sentinel node nor any other lymph node contained metastatic carcinoma. In 5 cases the sentinel node was in the mediastinum and documented unexpected N2 disease. In 19 patients no sentinel node was found. Final lymph node statuses were N0 in 13 patients, N1 in 5, and N2 in 1. CONCLUSIONS: The use of isosulfan blue for intraoperative lymphatic mapping is feasible. The specificity in our experience was good; 9 of 9 patients with negative sentinel nodes were found to be N0 on the final pathology report. Unexpected N2 disease was found in 5 patients. The accumulation of further experience will determine the role of the sentinel node technique in patients with non-small cell lung cancer.

Pathogenesis and management of persistent postthoracotomy pain.

Persistent chest wall pain is common after thoracotomy and is usually caused by recurrence or progression of malignancy. It should prompt efforts to identify and treat the causative disease. A minority of patients experience persistent pain not related to neoplasm. This pain may last for years, but is usually not severe. A small subset of these patients experience persistent severe pain, which may be debilitating. The pain may be owing to various causes. Diagnosis and treatment should be individualized and directed toward the causes believed to be present. First-line pharmacologic therapies include NSAIDs, tricyclic antidepressants, antiepileptics, and low-dose opioids. Some patients require more sophisticated treatment from multidisciplinary pain-management clinics. This treatment may include nerve blocks, physical therapy, sympathectomy, cryoneurolysis, or long-term neuromodulation with epidural analgesia or spinal cord stimulation. Because of the severe pain these patients may experience and the difficulty and expense associated with treatment, prevention may be the best strategy for dealing with this problem. Recent laboratory and clinical studies indicate that minimizing perioperative pain can suppress certain alterations in the nervous system that may prevent the genesis and maintenance of chronically painful conditions. This suggests that strategies for avoiding PTPS may begin with aggressive perioperative anesthetic and analgesic techniques. More effective application of knowledge already available from laboratory studies awaits further clinical trials. New drugs such as NMDA inhibitors hold promise for more effective treatment in the future.

Metastatic squamous cell carcinoma of the mediastinum with unknown primary tumor.

Although metastatic carcinoma from an unknown primary tumor is known to occur, the combination of squamous cell carcinoma histologic findings and a mediastinal location is quite unusual. The evaluation of a case of a patient with a posterior mediastinal mass, eventually shown to be metastatic squamous cell carcinoma of the mediastinum with unknown primary tumor, is described herein. Resection of the lymph node mass was performed and was followed by chemoradiation for presumed lung cancer.

Thoracoscopy: current status.

This article presents the current status of thoracoscopy in clinical practice. Aspects of its use in diagnostic, staging, and therapeutic areas are reviewed as regards diseases of the pleura, lung, and mediastinum. Controversies and evolving applications are identified.