Influence of body composition on the metabolic rate of nestling European shags (Phalacrocorax aristotelis)

During the early development of avian nestlings, their mass-specific resting metabolic rate (RMR) changes in a biphasic pattern with the peak value often being much higher than that expected for an adult bird of similar body mass. In the present study we examined the possible influence of variations in the size of internal organs in “setting” the high RMR and peak metabolic rate (PMR) during development in a large altricial species, the European shag (Phalacrocorax aristotelis). Thermoneutral RMR and cold-exposure induced PMR were measured in nestlings 15 days old, the age at which the highest RMR occurred during development. Body mass averaged 414 g. Mean values of RMR and PMR were 5.75 W and 9.08 W, respectively; the RMR value corresponds to approximately 250% of the expected value for an adult non-passerine bird of similar body mass. The masses of all the organs measured (breast and leg muscles, heart, liver, intestine, and kidney) varied isometrically with total body mass. However, large chicks had a significantly lower fractional water content than small chicks, suggesting that the former had achieved a higher level of functional maturity. In contrast to what has been suggested for adult birds in general, the heart and kidney masses of shag nestlings were not significantly correlated with the metabolic rates. The intestine length, in contrast, was highly and positively correlated with both the RMR and the PMR, i.e. intestine length was a better predictor of RMR and PMR than was total body mass. In addition, liver mass was positively correlated with RMR. The results of the present study suggest that the liver in particular may play a key role in establishing the high, mass-specific RMR which is attained during development in bird chicks. Our results also support previous suggestions that early in their development, altricial chicks mainly allocate energy to the growth of `energy-processing' organs (such as the intestine and liver) rather than to `energy-consuming' organs. Accepted: 3 March 1999     

Seasonal trends in body mass, food intake and resting metabolic rate, and induction of metabolic depression in arctic foxes (Alopex lagopus) at Svalbard

 Post-absorptive resting metabolic rates (RMRs), body mass and ad libitum food intake were recorded on an annual cycle in captive arctic foxes (Alopex lagopus) at Svalbard. During the light season in May and in the dark period in November, RMR during starvation and subsequent re-feeding were also measured. In contrast to earlier findings, the present study indicated a seasonal trend in post-absorptive RMR (in W · kg⁻¹ and W · kg^−0.75). The values in the light summer were 15% and 11% higher than the values in the dark winter, suggesting a physiological adaptation aiding energy conservation during winter in arctic foxes. Body mass and ad libitum food intake varied inversely through the year. A significant reduction in RMR (in W and W · kg^−0.75) with starvation (metabolic depression) was recorded both in May and November, indicating an adaptation to starvation in arctic foxes. The lack of metabolic depression during a period of starvation that was concomitant with extremely cold ambient temperatures in November 1994 indicates that metabolic responses to starvation may be masked by thermoregulatory needs. At very low ambient temperatures, arctic foxes may require increased heat production which cannot be achieved via below-average rates of metabolism. Accepted: 7 June 1999     

NEIL3-Dependent Regulation of Cardiac Fibroblast Proliferation Prevents Myocardial Rupture

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Detection of bone erosions in rheumatoid arthritis wrist joints with magnetic resonance imaging, computed tomography and radiography

Background

The objectives of the present study were, with multidetector computed tomography (CT) as the reference method, to determine the performance of magnetic resonance imaging (MRI) and radiography for the detection of bone erosions in rheumatoid arthritis wrist bones, and to test whether measuring volumes of erosions on CT and MRI is reproducible and correlated to semiquantitative assessments (scores) of erosions on CT, MRI and radiography.

Methods

Seventeen patients with rheumatoid arthritis and four healthy control individuals underwent CT, MRI and radiography of one wrist, performed on the same day. CT was performed on a Philips Mx8000IDT unit (voxel size 0.4 mm × 0.4 mm × 1 mm) and MRI was performed on a Philips Panorama 0.6T unit (voxel size 0.4 mm × 0.4 mm × 0.4 mm). Images were evaluated separately for erosions in all wrist bones and were scored according to the principles of the Outcome Measures in Rheumatology Rheumatoid Arthritis MRI Scoring System (CT and MRI) and the Sharp/van der Heijde (radiographs) scoring methods. Measurements of erosion volumes of all erosions were performed twice with a 1-week interval.

Results

With CT as the reference method, the overall sensitivity, specificity and accuracy (concordance) of MRI for detecting erosions were 61%, 93% and 77%, respectively, while the respective values were 24%, 99% and 63% for radiography. The intramodality agreements when measuring erosion volumes were high for both CT and MRI (Spearman correlation coefficients 0.92 and 0.90 (both P < 0.01), respectively). Correlations between volumes and scores of individual erosions were 0.96 for CT and 0.99 for MRI, while they were 0.83 (CT) and 0.80 (MRI) for persons' total erosion volume and total score (all P < 0.01).

Conclusion

With CT as the reference method, MRI showed moderate sensitivity and good specificity and accuracy for detection of erosions in rheumatoid arthritis and healthy wrist bones, while radiography showed very low sensitivity. The tested volumetric method was highly reproducible and correlated to scores of erosions.     

Complete mitochondrial genome sequences of the Arctic Ocean codfishes <Emphasis Type="Italic">Arctogadus glacialis</Emphasis> and <Emphasis Type="Italic">Boreogadus saida</Emphasis> reveal oriL and tRNA gene duplications

We have determined the complete mitochondrial genome sequences of the codfishes Arctogadus glacialis and Boreogadus saida (Order Gadiformes, Family Gadidae). The 16,644 bp and 16,745 bp mtDNAs, respectively, contain the same set of 37 structural genes found in all vertebrates analyzed so far. The gene organization is conserved compared to other Gadidae species, but with one notable exception. B. saida contains heteroplasmic rearrangement-mediated duplications that include the origin of light-strand replication and nearby tRNA genes. Examination of the mitochondrial control region of A. glacialis, B. saida, and four additional representative Gadidae genera identified a highly variable domain containing tandem repeat motifs in A. glacialis. Mitogenomic phylogeny based on the complete mitochondrial genome sequence, the concatenated protein-coding genes, and the derived protein sequences strongly supports a sister taxa affiliation of A. glacialis and B. saida.     

Dendritic Cells Loaded with Tumor Antigens and a Dual Immunostimulatory and Anti-Interleukin 10-Specific Small Interference RNA Prime T Lymphocytes against Leukemic Cells

Vaccines using dendritic cells (DCs) harboring leukemic antigens to stimulate T cells is a possible treatment of acute myeloid leukemia (AML). Limitations of breaking tolerance to leukemic cells and lack of specific activation of T cell-mediated cytotoxicity may explain the discouraging clinical results with this approach. To break self-tolerance against AML cells, we loaded DCs with AML antigens and a bifunctional small interference (si) RNA targeting interleukin (IL) 10 and simultaneously activating toll-like receptors (TLRs). In vitro, this active siRNA inhibited (P < .05) IL-10 production by silencing the IL-10 gene in DCs. The active siRNA stimulated production of tumor necrosis factor α, implying activation of TLRs. Vaccination in a nonimmunogenic rat model mimicking human AML with the loaded DCs induced a substantial and specific T-cell cytotoxicity. Leukemic rats treated with the active siRNA lived longer and had markedly less leukemic cell mass infiltrating their bone marrow compared with rats given inactive siRNA (P < .05). Furthermore, compared with inactive siRNA treatment, the active siRNA led to significantly less extramedullar leukemic dissemination, evidenced by reduced matrix metalloproteinase activity and smaller spleens. Our data demonstrate that this bifunctional siRNA may work as an immunomodulatory drug with antileukemic properties.