Fibre architecture and song activation rates of syringeal muscles are not lateralized in the European starling.

The songbird vocal organ, the syrinx, is composed of two sound generators, which are independently controlled by sets of two extrinsic and four intrinsic muscles. These muscles rank among the fastest vertebrate muscles, but the molecular and morphological foundations of this rapid physiological performance are unknown. Here we show that the four intrinsic muscles in the syrinx of male European starlings (Sturnus vulgaris) are composed of fast oxidative and superfast fibres. Dorsal and ventral tracheobronchialis muscles contain slightly more superfast fibres relative to the number of fast oxidative fibres than dorsal and ventral syringealis muscles. This morphological difference is not reflected in the highest, burst-like activation rate of the two muscle groups during song as assessed with electromyographic recordings. No difference in fibre type ratio was found between the corresponding muscles of the left and right sound generators. Airflow and electromyographic measurements during song indicate that maximal activation rate and speed of airflow regulation do not differ between the two sound sources. Whereas the potential for high-speed muscular control exists on both sides, the two sound generators are used differentially for modulation of acoustic parameters. These results show that large numbers of superfast fibre types are present in intrinsic syringeal muscles of a songbird, providing further confirmation of rapid contraction kinetics. However, syringeal muscles are composed of two fibre types which raises questions about the neuromuscular control of this heterogeneous muscle architecture.

Anatomy and histochemistry of flight muscles in a wing-propelled diving bird, the Atlantic puffin, Fratercula arctica.

Twenty-three species within the avian family Alcidae are capable of wing-propelled flight in the air and underwater. Alcids have been viewed as Northern Hemisphere parallels to penguins, and have often been studied to see if their underwater flight comes at a cost, compromising their aerial flying ability. We examined the anatomy and histochemistry of select wing muscles (Mm. pectoralis, supracoracoideus, latissimus dorsi caudalis, coracobrachialis caudalis, triceps scapularis, and scapulohumeralis caudalis) from Atlantic puffins (Fratercula arctica) to assess if the muscle fiber types reveal the existence of a compromise associated with "dual-medium" flight. Pectoralis was found to be proportional in size with that of nondiving species, although the supracoracoideus was proportionally larger in puffins. Muscle fiber types were largely aerobic in both muscles, with two distinct fast-twitch types demonstrable: a smaller, aerobic, moderately glycolytic population (FOg), and a larger, moderately aerobic, glycolytic population (FoG). The presence of these two fiber types in the primary flight muscles of puffins suggests that aerial and underwater flight necessitate a largely aerobic fiber complement. We suggest that alcids do not represent an adaptive compromise, but a stable adaptation for wing-propelled locomotion both in the air and underwater.

Anatomy and histochemistry of spread-wing posture in birds. 2. Gliding flight in the California gull, Larus californicus: a paradox of fast fibers and posture.

Gliding flight is a postural activity which requires the wings to be held in a horizontal position to support the weight of the body. Postural behaviors typically utilize isometric contractions in which no change in length takes place. Due to longer actin-myosin interactions, slow contracting muscle fibers represent an economical means for this type of contraction. In specialized soaring birds, such as vultures and pelicans, a deep layer of the pectoralis muscle, composed entirely of slow fibers, is believed to perform this function. Muscles involved in gliding posture were examined in California gulls (Larus californicus) and tested for the presence of slow fibers using myosin ATPase histochemistry and antibodies. Surprisingly small numbers of slow fibers were found in the M. extensor metacarpi radialis, M. coracobrachialis cranialis, and M. coracobrachialis caudalis, which function in wrist extension, wing protraction, and body support, respectively. The low number of slow fibers in these muscles and the absence of slow fibers in muscles associated with wing extension and primary body support suggest that gulls do not require slow fibers for their postural behaviors. Gulls also lack the deep belly to the pectoralis found in other gliding birds. Since bird muscle is highly oxidative, we hypothesize that fast muscle fibers may function to maintain wing position during gliding flight in California gulls.

Morphology of the antebrachial musculature of the American kestrel, Falco sparverius (aves).

The antebrachial musculature of the American kestrel (Falco sparverius) is described. This fills a gap in the avian morphology literature, and provides a reference for future comparative, functional and systematic studies. A table of synonyms-homologs is provided for each muscle as a reference frame for over 100 years of avian anatomical literature.

Pectoralis muscle morphology in the little brown bat, Myotis lucifugus: a non-convergence with birds.

Recent studies of muscle architecture demonstrate that many mammalian muscles are composed of short, interdigitating fibers. In addition, the avian pectoralis, a muscle capable of producing high frequency oscillations has been shown to possess a serially arranged pattern of muscle endplate in all sizes of birds studied. The pectoralis muscle of the little brown bat, Myotis lucifugus (Chiroptera: Vespertilionidae), is composed of fairly uniform fibers that span the length of the muscle and is characterized by a zone of motor endplates within the middle third of the muscle. The homogeneous fiber architecture of the bat pectoralis muscle is in contrast to the serial arrangement of endplates (and presumably muscle fibers) in the avian pectoralis in species equivalent in size to Myotis. The short fiber organization and motor endplate pattern observed in most birds is thus not a requisite design for flying vertebrates.

The morphological basis of folded-wing posture in the American kestrel, Falco sparverius.

Gross dissection and histochemical analysis of the shoulder musculature of the American kestrel, Falco sparverius, revealed that four muscles are specialized for slow contraction and may function in the postural control of the folded wing. Mm. latissimus dorsi pars cranialis, scapulohumeralis cranialis, and brachialis were found to contain greater than 95% tonic fibers, whereas M. deltoideus minor was found to possess a relatively even mix of fast-twitch and tonic muscle fibers. M. latissimus dorsi pars cranialis, M. scapulohumeralis cranialis, and M. deltoideus minor all cross the shoulder joint caudally to the articulation, and M. brachialis crosses the elbow joint on the ventral surface of the forearm. This paper suggests postural muscles have largely been ignored in studies of avian musculature, and the need to consider a variety of possible muscle functions when analyzing locomotor muscle functions.

Hyperbaric oxygen toxicity: role of thromboxane.

Exposing rabbits for 1 h to 100% O2 at 4 atm barometric pressure markedly increases the concentration of thromboxane B2 in alveolar lavage fluid [1,809 +/- 92 vs. 99 +/- 24 (SE) pg/ml, P less than 0.001], pulmonary arterial pressure (110 +/- 17 vs. 10 +/- 1 mmHg, P less than 0.001), lung weight gain (14.6 +/- 3.7 vs. 0.6 +/- 0.4 g/20 min, P less than 0.01), and transfer rates for aerosolized 99mTc-labeled diethylenetriamine pentaacetate (500 mol wt; 40 +/- 14 vs. 3 +/- 1 x 10(-3)/min, P less than 0.01) and fluorescein isothiocyanate-labeled dextran (7,000 mol wt; 10 +/- 3 vs. 1 +/- 1 x 10(-4)/min, P less than 0.01). Pretreatment with the antioxidant butylated hydroxyanisole (BHA) entirely prevents the pulmonary hypertension and lung injury. In addition, BHA blocks the increase in alveolar thromboxane B2 caused by hyperbaric O2 (10 and 45 pg/ml lavage fluid, n = 2). Combined therapy with polyethylene glycol- (PEG) conjugated superoxide dismutase (SOD) and PEG-catalase also completely eliminates the pulmonary hypertension, pulmonary edema, and increase in transfer rate for the aerosolized compounds. In contrast, combined treatment with unconjugated SOD and catalase does not reduce the pulmonary damage. Because of the striking increase in pulmonary arterial pressure to greater than 100 mmHg, we tested the hypothesis that thromboxane causes the hypertension and thus contributes to the lung injury. Indomethacin and UK 37,248-01 (4-[2-(1H-imidazol-1-yl)-ethoxy]benzoic acid hydrochloride, an inhibitor of thromboxane synthase, completely eliminate the pulmonary hypertension and edema.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphology of the lingual apparatus of the domestic chicken, Gallus gallus, with special attention to the structure of the fasciae.

A detailed redescription of the mechanically interacting structural elements of the lingual apparatus of the domestic chicken, Gallus gallus, revealed the functional and constructional role of organized connective tissue (i.e., ligaments and fasciae) as structural elements that ensure the proper biomechanical interactions among the various structures within the lingual apparatus (e.g., cartilaginous and bony skeletal elements, muscles, salivary glands, epithelial structures). Fasciae, together with extrinsic muscles, also connect the lingual apparatus to the other components of the feeding apparatus, such as the skull, jaw apparatus, and larynx. For example, the hyoid apparatus is attached to the skull by a sheath-like fascia (F. vaginalis), the internal structure of which is described here for the first time. Thus, the hyoid suspension in birds differs fundamentally from that in mammals. This study is the first to examine all biomechanically functioning structural elements that are part of the galliform lingual apparatus in a systematic and comprehensive manner. It also provides a set of novel characters that may be useful for future comparative studies in evolutionary and functional morphology.

Communicating health information to the public: effectiveness of a newsletter.

Following a review of health information campaign issues and research on the efficacy of selected communication channels, this paper reports an investigation of a specific medium--a health information newsletter--including whether and how much of it recipients read, its perceived information value, its impact on self-reported actions, its comparative role as a source of health information, and the extent to which results vary with selected characteristics of recipients who responded to a mail survey (n = 887). Results indicate that the newsletter is read and utilized by most recipients and serves for many as a major source of health information. Moreover, there is evidence of direct and indirect newsletter effects on respondents' self-reported health practices. Findings varied significantly with the sex and health professional status of recipients.

Desulfurization of coal.

Coal combustion is the largest single source of sulfur oxide pollution. Treatment of some major representative U.S. coals with aqueous ferric solution removes 40 to 75 percent of the sulfur content through near quantitative oxidation of the pyritic sulfur contained in the coal matrix. Elemental sulfur and iron sulfate are recovered as products of the reaction. Engineering assessment indicates that the system, when fully developed, offers high potential for the economic abatement of sulfur oxide pollution.