11 research outputs found
Intraspecific Correlations of Basal and Maximal Metabolic Rates in Birds and the Aerobic Capacity Model for the Evolution of Endothermy
The underlying assumption of the aerobic capacity model for the evolution of endothermy is that basal (BMR) and maximal aerobic metabolic rates are phenotypically linked. However, because BMR is largely a function of central organs whereas maximal metabolic output is largely a function of skeletal muscles, the mechanistic underpinnings for their linkage are not obvious. Interspecific studies in birds generally support a phenotypic correlation between BMR and maximal metabolic output. If the aerobic capacity model is valid, these phenotypic correlations should also extend to intraspecific comparisons. We measured BMR, Msum (maximum thermoregulatory metabolic rate) and MMR (maximum exercise metabolic rate in a hop-flutter chamber) in winter for dark-eyed juncos (Junco hyemalis), American goldfinches (Carduelis tristis; Msum and MMR only), and black-capped chickadees (Poecile atricapillus; BMR and Msum only) and examined correlations among these variables. We also measured BMR and Msum in individual house sparrows (Passer domesticus) in both summer, winter and spring. For both raw metabolic rates and residuals from allometric regressions, BMR was not significantly correlated with either Msum or MMR in juncos. Moreover, no significant correlation between Msum and MMR or their mass-independent residuals occurred for juncos or goldfinches. Raw BMR and Msum were significantly positively correlated for black-capped chickadees and house sparrows, but mass-independent residuals of BMR and Msum were not. These data suggest that central organ and exercise organ metabolic levels are not inextricably linked and that muscular capacities for exercise and shivering do not necessarily vary in tandem in individual birds. Why intraspecific and interspecific avian studies show differing results and the significance of these differences to the aerobic capacity model are unknown, and resolution of these questions will require additional studies of potential mechanistic links between minimal and maximal metabolic output
Daily energy expenditure in precocial shorebird chicks: smaller species perform at higher levels
Thermogenic mechanisms during the development of endothermy in juvenile birds
Abstract
The use of regulatory and obligatory heat production mechanisms were
studied in
juvenile birds during the development of endothermy.
The development of shivering thermogenesis was studied in the pectoral and
gastrocnemius muscles of the altricial domestic pigeon and in three precocial
galliforms (Japanese quail, grey partridge and domestic fowl). The development of
shivering was the determinant for the beginning of endothermy. Homeothermy also
necessitated avoidance of excess heat loss by insulation and behavioural
thermoregulation. In the precocial species, shivering thermogenesis was present
in the leg muscles of the youngest age groups (1-2 d) studied. Breast muscles
contributed shivering from the second post-hatching week. In the altricial
pigeons, significant thermogenesis was apparent later than in the precocials, at
the age of 6 d. In contrast to the precocials, the pectoral muscles of the
altricials were the most significant heat production tissues. In newly-hatched
partridges and pigeons, incipient shivering did not result in significant heat
production.
The ability to produce heat in cold by putative nonshivering thermogenesis
was
studied in Japanese quail chicks and domestic ducklings. In both species,
three-week cold acclimation resulted in morphometric and physiological changes,
but there was no clear evidence of nonshivering thermogenesis. The lack of NST
was evident because an increase in shivering amplitude at least in one of the
muscles studied paralleled an increase in oxygen consumption. Consequently,
shivering thermogenesis was probably the only mode of regulatory heat
production.
The amplitudes of shivering EMGs measured during cold exposure were
dependent on
the coexistence of postprandial thermogenesis or exercise. Japanese quail chicks
were able to substitute shivering thermogenesis partially with postprandial heat
production when nourished. Bipedal exercise both inhibited shivering in pectorals
directly via inhibitory neural circuits and stimulated it indirectly via
decreased body temperature. Because of increased heat loss, exercise was not used
as a substitute for shivering.
Shivering is a flexible mode of thermogenesis and its magnitude can be
adjusted
according to the magnitude of obligatory thermogenesis. The adjustment works
towards energy saving by avoidance of the summation of different modes of heat
production. The prerequisite for successful adjustment of shivering is adequate
insulation, whose role in preventing excessive heat loss is pronounced during
exercise. It is concluded that the energetics of posthatching thermoregulation
includes the potential for optimizations in energy use in order to avoid
dissipation of waste energy as heat
Association of rheumatoid arthritis disease activity and antibodies to periodontal bacteria with serum lipoprotein profile in drug naive patients
Abstract
Objective: We investigated lipid concentrations, particle sizes and antibodies binding to periodontal bacteria Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis and to malondialdehyde-acetaldehyde (MAA) modified low-density lipoprotein in immunoglobulin (Ig) class A, G and M among patients with newly diagnosed rheumatoid arthritis (RA) in a population-based cohort.
Methods: Concentrations and sizes of lipoprotein particles analysed by proton nuclear magnetic resonance spectroscopy and antibody levels to MAA modified low-density lipoprotein were studied at baseline and after one-year of follow-up. Serum Ig A and G class antibodies to periodontal bacteria were determined at baseline.
Results: Sixty-three patients were divided into tertiles according to disease activity by disease activity score with 28 joint count and erythrocyte sedimentation rate (ESR) (<3.9, 3.9–4.7, >4.7). Small low-density lipoprotein concentration was lowest in the tertile with the highest disease activity. In high-density lipoprotein, the concentrations of total, medium and small particles decreased with disease activity. The particle size in low-density lipoprotein associated with disease activity and the presence of antibodies to P. gingivalis. Ig G and M antibodies to MAA modified low-density lipoprotein correlated with disease activity. Inflammation associated changes faded by one year.
Conclusions: Drug naive RA patients had proatherogenic changes in lipid profiles, but they were reversible, when inflammation diminished
Effects of Slaughterhouse Offal and Fish Mixture Based Diets on Production Performance of Blue and Silver Foxes
Retinoid receptor alpha and beta expression in serous ovarian tumors
The expression of retinoid acid receptors alpha (RAR alpha) and beta (RAR beta) and estrogen receptor alpha (ER alpha) was assessed by immunohistochemistry and Western blotting in normal ovaries, serous cystadenoma (n = 20), serous borderline (n = 14), and serous ovarian cancer (n = 47) and was correlated in cancer cases with stage, grade, progress-free survival (PFS), and survival. RAR alpha was increasingly expressed in benign cystadenomas, borderline, and low-stage and advanced-stage neoplasms (p < 0.001). In stage III, G3 serous carcinoma, increased RAR alpha expression was an independent prognostic factor associated with lower chemoresponse to first-line chemotherapy (taxol and carboplatin) and shorter PFS (p < 0.002). RAR beta and ER alpha expression did not correlate with RAR alpha tumor characteristics or PFS and survival. Copyright (C) 2008 S. Karger AG, Basel