Sustained swimming speeds and myotomal muscle function in the trout, Salmo gairdneri

Rainbow trout were trained for 3–4 weeks in a flume at swimming speeds of 1, 2 and 3 l s⁻¹. For each experiment growth rates were estimated and by measuring the hypertrophy of red and mosaic skeletal muscle fibres their function was described at particular swimming speeds and compared with earlier experiments on coalfish using the same technique.
Maximum growth, compared with controls in still water, occurred at swimming speeds of 1 l s⁻¹. At this speed the trout mosaic muscle fibres hypertrophied by 40% but the red muscle fibres showed only a 25% hypertrophy. It is suggested that natural swimming speeds are close to 1Ls^−l and the trout mosaic fibres are better adapted for use at this speed in comparison with coalfish white muscle fibres.     

Functional analysis of frog pectoral girdles. The epicoracoid cartilages

Two types of pectoral girdles occur among frogs. Arciferal girdles have overlapping epicoracoid cartilages; in firmisternal girdles the epicoracoid cartilages are fused along the ventral midline. Cineradiographic experiments of jumping frogs show that the epicoracoid cartilages of arciferal girdles move relative to each other at the time of landing. Recordings of landings on a force platform reveal that the pectoral girdle of frogs is loaded compressively through the glenoid. This loading regime coupled with differential mobility between firmisternal and arciferal girdles results in differences in stress distribution in the two girdles during landing. The patterns of stress distribution suggest that variation seen among frogs in other aspects of pectoral morphology in addition to the condition of the epicoracoid cartilages may be best understood when analysed from a biomechanical perspective.     

Culture perfusion schedules influence the metabolic activity and granulocyte-macrophage colony-stimulating factor production rates of human bone marrow stromal cells

The metabolic function and GM-CSF production rates of adherent human bone marrow stromal cells were investigated as functions of medium and serum feeding rates. A range of medium exchange schedules was studied, ranging from a typical Dexter culture protocol of one weekly medium exchange to a full media exchange daily, which more closely approximates what bone marrow cells experience in situ. Glucose consumption was found to be significantly higher at full daily exchange rate than at any other exchange schedule examined. However, the lactate yield on glucose was a constant, at 1.8 mol/mol, under all conditions considered. Differential serum vs. medium exchange experiment showed that both serum supply and medium nutrients were responsible for the altered behavior at high exchange rates. Glutamine consumption was found to be insignificant under all culture conditions examined. A change in exchange schedule from 50% daily medium exchange to full daily medium exchange after 14 days of culture was found to result in a transient production of GM-CSF and a change in metabolic behavior to resemble that of cultures which had full daily exchange from day one. These results suggest that both stromal cell metabolism and GM-CSF production are sensitive to medium exchange schedules. Taken together, the data presented indicate that attempts to model the function of human bone marrow in vitro may be well served by beginning with medium exchange schedules that more closely mimic the in vivo physiologic state of bone marrow.     

A biomechanical perspective on the use of forelimb length as a measure of sexual selection in frogs

Differences in forelimb length between male and female frogs and between amplexing and non-amplexing males have been interpreted to be the results of sexual selection on forelimb length. The causal feature of the forelimb that has been posited to cause such selection is the observation that non-amplexing males attempt to disrupt breeding by prying amplexing males from females. A biomechanical model of forelimb function suggests that total length per se may not be the most appropriate measure to use. There are more functionally significant aspects of forelimb morphology, such as lever arm lengths, that should influence amplexing ability and may make measures of overall forelimb length misleading. This example highlights the relevance of functional analysis to current questions in evolutionary biology that rely on postulated roles for morphological structures under selection.     

Fibreoptic bronchoscopy: ten years on.

Fibreoptic bronchoscopy was introduced more than 10 years ago and is now in many centres a routine diagnostic procedure, having superseded rigid bronchoscopy. Its major role is in the diagnosis of bronchial carcinoma, where the results are as good as, if not better than, results with the rigid instrument. Other major applications have been found in investigating haemoptysis, transbronchial lung biopsy in interstitial lung disease, and in the critically ill patient in the intensive care unit. More recently, the instrument has been used to perform bronchoalveolar lavage in investigating interstitial lung diseases and to enable lobar and segmental lung function studies to be performed. Fibreoptic bronchoscopy is a major advance in the diagnosis of pulmonary diseases, but there will always be times when rigid bronchoscopy is preferable.     

Transbronchial lung biopsy through fibreoptic bronchoscope in diagnosis of sarcoidosis.

Sarcoidosis was ultimately diagnosed in a consecutive series of 79 patients, of whom 24 presented with unusual features. Histological support for this diagnosis was obtained in 37 out of 42 patients who underwent transbronchial biopsy; epithelioid and giant-cell granulomas were also found on biopsy of the bronchial mucosa in 17 out of 22 patients. Kveim tests were completed in 44 patients: results were positive in 19, equivocal in 11, and negative in 14. In 16 patients histological support was obtained on biopsy of various other tissues. The clinical presentation of the disease and the degree of histological support provided by the various procedures used in reaching a diagnosis of sarcoidosis varied considerably. Transbronchial biopsy of the lung is a useful advance in diagnosing sarcoidosis and provided a higher diagnostic yield than any other method.     

Mechanisms of spacing in groups of juncos: Measurement of behavioural tendencies in social situations

To investigate behavioural mechanisms that regulate the spacing of individuals, we studied aggression, approach, and avoidance of captive male juncos (Junco hyemalis) in relation to the distance between individuals. We measured behavioural tendencies by analysing the terminations of social states so as to determine the instantaneous probability rates of terminal actions. These rates permit accurate comparisons of behavioural tendencies in different social situations. An individual's tendencies to supplant, approach, or withdraw from an opponent depended on the dominance relationship of the two birds and on the distance between them. Interactions did not vary with the magnitude of the difference between opponents' ranks. The dependence of aggression, approach, and avoidance on the distance between opponents controls the spacing of individuals.