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Biomedical subjects

David L Swanson

Publications and source records attributed to David L Swanson.

12 recordsLinked to original sources
PubMed2006

The relationship of plasma indicators of lipid metabolism and muscle damage to overnight temperature in winter-acclimatized small birds.

Plasma glycerol and triglyceride levels and creatine kinase (CK) activity may increase during long-distance flights in migratory birds, but plasma profiles of these metabolites have not previously been reported for small birds during thermoregulation in cold climates. We measured early morning levels of plasma glycerol, triglycerides and CK activity in four species of small birds overwintering in South Dakota, Junco hyemalis, Spizella arborea, Passer domesticus, and Carduelis tristis. We hypothesized that metabolite levels and CK activity might vary with overnight temperature (measured as the temperature just prior to dawn), with higher levels during colder temperatures which require elevated thermogenesis. Triglyceride and glycerol levels were not significantly related to temperature for any of the four species. Triglyceride levels were significantly positively associated with time since sunrise in J. hyemalis and C. tristis, and the time-temperature interaction was significant for S. arborea, suggesting rapid replacement of fat stores. Plasma glycerol levels were also significantly positively related to time since sunrise in J. hyemalis and C. tristis, but not in other species. Plasma CK activity showed a significant negative relationship to overnight temperature only for S. arborea. These results suggest that triglycerides do not comprise a major contribution to lipid supply during intense shivering in small birds. Similarly, intense shivering does not generally appear to result in muscle damage in small birds.

Acclimatization↗
PubMed2006

Optical coherence tomography for the characterization of basal cell carcinoma in vivo: a pilot study.

BACKGROUND: Optical coherence tomography combines principles of ultrasonography and optical interferometry to provide real-time cross-sectional images of subsurface microstructure of tissue in vivo. OBJECTIVE: The purpose of this pilot study was to define and characterize basal cell carcinoma by using optical coherence tomography. METHODS: Twenty-three patients with 49 lesions clinically suggestive of superficial basal cell carcinoma were recruited. Optical coherence tomography was used to characterize the features of the pearly papules in real time and in vivo. Shave biopsy and light microscopic images were compared with images from optical coherence tomography. RESULTS: Basal cell carcinoma was identified in 27 patients; all 27 had optical coherence tomographic images for comparison. Seven images were uninterpretable, probably because of technical problems. Of the remainder, 20 sites matched the histologic features seen on light microscopy, with excellent correlation between optical coherence tomographic images and histopathologic features of superficial, nodular, micronodular and infiltrative basal cell carcinomas. LIMITATIONS: This study was limited by the small number of patients examined. Also, as this study was not designed as an intent-to-diagnose study, the actual predictive value of optical coherence tomography technology remains unproven. CONCLUSIONS: Optical coherence tomography technology has potential for the diagnosis and histopathologic characterization of basal cell cancer. Additional studies to determine any practical role for optical coherence tomography are indicated.

Aged↗
PubMed2006

Genital lymphangioma with recurrent cellulitis in men.

BACKGROUND: Lymphangioma circumscriptum rarely occurs on the penis. This report describes a patient observed in private practice who presented with recurrent unexplained cellulitis of the penis for whom this diagnosis was not initially apparent. METHODS: Diagnosis of lymphangioma in this patient resulted in a retrospective records review of the Mayo Clinic experience with patients who had genital lymphangioma and cellulitis. RESULTS: Six other male patients with recurrent cellulitis complicating genital lymphangioma were identified. Five of these six patients were managed with antibiotic prophylaxis. CONCLUSIONS: Compromised lymphatic drainage should be suspected in male patients with otherwise unexplained penile swelling or cellulitis. These patients usually require long-term antibiotic prophylaxis for recurrent infection.

Adolescent↗
PubMed2006

A comparative analysis of thermogenic capacity and cold tolerance in small birds.

Small birds showing marked seasonal changes in cold tolerance also exhibit winter increases in summit metabolic rate (Msum=maximum cold-induced thermogenesis or thermogenic capacity) relative to summer birds. However, some birds show modest seasonal changes in cold tolerance without winter increases in Msum and others exhibit large seasonal changes in cold tolerance with only minor changes in Msum. Thus, the degree of correlation between cold tolerance and Msum is uncertain and no interspecific study has directly addressed this question. In this study, we measured cold tolerance and Msum in summer- (21 species) and winter- (11 species) acclimatized birds from southeastern South Dakota. Msum was measured as the maximum oxygen consumption attained during exposure of individual birds to a declining series of temperatures in 79% helium/21% oxygen (helox). Cold tolerance was measured as the temperature at cold limit (TCL), which is the helox temperature that induced hypothermia in individual birds. Residuals from allometric regressions of logMsum and logTCL were significantly and negatively related for summer (R2=0.34, P=0.006) and winter (R2=0.40, P=0.037) birds. Data were also subjected to a comparative analyses with phylogenetically independent contrasts to remove potential confounding effects of phylogeny, and results were similar to the non-phylogenetic analyses, with significant negative correlations in both summer (R2=0.47, P<0.001) and winter (R2=0.40, P=0.049). Thus, birds with high Msum tended to show reduced TCL (i.e. high cold tolerance), suggesting that cold tolerance and summit metabolism are phenotypically linked in small birds.

Adaptation, Physiological↗
PubMed2006

Skin lesions in barracks: consider community-acquired methicillin-resistant Staphylococcus aureus infection instead of spider bites.

Recent outbreaks of mysterious skin lesions on multiple personnel at several military facilities were initially blamed on spiders. Requests were made for pest inspection and control to remedy the situation. Greater scrutiny of the situation led to a hypothesis that instead of spiders, an infectious outbreak of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) should be investigated as the etiology. Subsequent culturing of the lesions on personnel at one facility confirmed this bacterial etiology. Barracks, as well as other close quarter military living conditions, are ripe environments for the establishment, persistence, and spread of CA-MRSA. Military medical personnel should consider CA-MRSA as a more likely etiologic agent than spider bites for cutaneous eruptions in which there are multiple lesions on one person or multiple patients with similar lesions.

Animals↗
PubMed2005

An umbilical polyp in an infant.

The persistence at birth of the omphalomesenteric (vitelline) duct may result in life-threatening consequences. Early identification of this congenital anomaly is essential for prompt surgical treatment to eliminate the risk of prolapse and herniation. A neonatal umbilical polyp may indicate the presence of an omphalomesenteric duct remnant. We describe the diagnosis and surgical treatment of an infant with an umbilical polyp. We also present an overview of the diagnosis and treatment of vitelline duct remnants and their associated anomalies.

Diagnosis, Differential↗
PubMed2002

Passerines versus nonpasserines: so far, no statistical differences in the scaling of avian energetics.

We analyzed and compared the scaling of both basal and maximal thermogenic metabolic rates in passerine and nonpasserine birds using conventional and phylogenetic methods. In spite of the presumed adaptive importance of both metabolic traits, few studies concerning both their relationships and their ecological and evolutionary constraints have been conducted. We found no statistical differences in the scaling of maximal metabolic rate between passerines and nonpasserines; hence, we suggest the use of a single allometric regression for this trait in birds. In addition, basal and maximal metabolic rates were indeed correlated after removing the effects of body mass and phylogeny. The apparent generality of this correlation within both birds and mammals reinforces the need for general ecological and physiological explanations for the evolution of endothermy.

Animals↗
PubMedDate not supplied

Loxoscelism.

Loxoscelism (bites by spiders of the genus Loxosceles) is the only proven arachnological cause of dermonecrosis. Although Loxosceles spiders can be found worldwide, their distribution is heavily concentrated in the Western Hemisphere, particularly the tropical urban regions of South America. Although Loxosceles bites are usually mild, they may ulcerate or cause more severe, systemic reactions. These injuries mostly are due to sphingomyelinase D in the spider venom. There is no proven effective therapy for Loxosceles bites, although many therapies are reported in the literature.

Humans↗
PubMedDate not supplied

Daily torpor in free-ranging whip-poor-wills (Caprimulgus vociferus).

The use of heterothermy is well documented in the order Caprimulgiformes, but there is conflicting information regarding whether whip-poor-wills are heterothermic. Consequently, we sought to rigorously examine the thermoregulatory abilities of this species. Our study was conducted in southeast South Dakota (42 degrees 47'N, 97 degrees 0'W), where 35 individuals were captured and outfitted with external, temperature-sensitive radio transmitters. We found evidence that whip-poor-wills used daily torpor during the autumn of 2000 and the spring of 2001 (n=12 torpor bouts, based on 346 bird-nights of observation). The average minimum skin temperature of two torpid whip-poor-wills (n=5 torpor bouts) in spring 2001 was 20.1 degrees +/-2.6 degrees C, and bouts of reduced skin temperature lasted an average of 360.0+/-93.7 min. The distribution of heterothermy within the Caprimulgiform phylogeny suggests that the trait is ancestral in the order. Specific heterothermic parameters, however, differ among the different species. In particular, the frequency of torpor use in whip-poor-wills is lower than for other species. These data suggest that several factors, including weather conditions and gender-specific reproductive ecology, influence the propensity of whip-poor-wills and other Caprimulgiformes to enter torpor.

Animals↗