The diet of strap-toothed whales (Mesoplodon layardii)

The food habits of strap-toothed whales ( Mesoplodon layardii ) were examined in detail using stomach contents from 14 stranded whales found on South African and New Zealand coasts. Although a few unidentified fish otoliths and crustacean remains were found in two of these stomachs, 24 species of oceanic squids (some of which occur at a great depth) accounted for 94.8% of counted prey items ( n = 232). Histioteuthis sp. and Taonius pavo were the predominant prey species (25.0 and 17.2% by number, 21.4 and 19.9% by mass, respectively). The presence of sub-Antarctic squid species suggested a northward migration to South African waters in late summer/autumn. Prey sizes were compared between males with fully grown strap-teeth and females/immature males without erupted teeth, using dorsal mantle lengths (DML) and weights of squids estimated from beak measurements. Although females/immature males ate longer squids than males, there was no significant difference in the estimated weights of squids eaten by the two groups. The presence of fully-erupted teeth in adult males, therefore, did not seem to influence the size of prey ingested, even though an adult male could only open its jaws about half as wide as a female. In general, the sizes of cephalopods eaten by strap-toothed whales were not significantly different from those eaten by smaller odontocetes, such as spotted dolphins and dwarf sperm whales, but were significantly smaller than those eaten by larger odontocetes, such as false killer, long-finned pilot, Cuvier's beaked, and southern bottlenose whales.     

Capillary recruitment and transit time in the rat lung

Presson, Robert G., Jr., Thomas M. Todoran, Bracken J. DeWitt, Ivan F. McMurtry, and Wiltz W. Wagner, Jr.Capillary recruitment and transit time in the rat lung.J. Appl. Physiol. 83(2): 543-549, 1997.Increasing pulmonary blood flow and the associated rise incapillary perfusion pressure cause capillary recruitment. The resultingincrease in capillary volume limits the decrease in capillary transittime. We hypothesize that small species with relatively high restingmetabolic rates are more likely to utilize a larger fraction ofgas-exchange reserve at rest. Without reserve, we anticipate thatcapillary transit time will decrease rapidly as pulmonary blood flowrises. To test this hypothesis, we measured capillary recruitment andtransit time in isolated rat lungs. As flow increased, transit timedecreased, and capillaries were recruited. The decrease in transit timewas limited by an increase in the homogeneity of the transit time distribution and an increased capillary volume due, in part, to recruitment. The recruitable capillaries, however, were nearly completely perfused at flow rates and pressures that were less thanbasal for the intact animal. This suggests that a limited reserve ofrecruitable capillaries in the lungs of species with high restingmetabolic rates may contribute to their inability to raiseO₂ consumption manyfold abovebasal values.

     

Governing equations of motion for the otolith organs and their response to a step change in velocity of the skull

The otolith organs are the linear motion sensors of the inner ear. They comprise an overdamped second-order system and respond to gravity and skull acceleration. The governing equations of motion which describe the relative displacement of the mass with respect to the skull are developed. When these equations are non-dimensionalized they indicate that the elastic term is almost negligible with respect to the viscous and inertial terms. For a step change in skull velocity an analytic solution is given for the elastic term equal to zero and numeric solutions are given for small values of the elastic term.     

Isolation of Legionella pneumophila from the blood of a patient with Legionnaires' disease.

Legionella pneumophila is rarely isolated from blood cultures. Presently most cases of Legionnaires'' disease are diagnosed retrospectively from the results of indirect fluorescent antibody tests, which possess inherent disadvantages. An 81-year-old woman with a history of diabetes mellitus presented symptoms of Legionnaires'' disease. Five hours before her death 1.5 mL of blood was withdrawn from a scalp vein and seeded to a culture medium. Following incubation for 3 days L. pneumophila serotype 1 was isolated.     

Germination dimorphism and developmental flexibility in the ruderal weed Heterotheca grandiflora

Summary Heterotheca grandiflora Nutt. (Asteraceae, tribe Astereae) is one of the few native Californian plant species increasing its range as a weed. The production of dimorphic seed, together with flexible development in either the annual or biennial habit, may contribute to its range expansion. Well dispersed disc achenes germinate rapidly to high percentages while poorly dispersed ray achenes show considerable dormancy, germinating at a much lower rate to lower final percentages. Ray achenes appear more sensitive to environmental factors and have more specific germination requirements than do disc achenes. Thus, germination is distributed in space and time. Plants growing as annuals have one flowering period while those acting as biennials may flower up to three times, although seed production differs greatly among the stages. These factors aid in forming the general purpose genotype so frequently encountered in weedy species.     

Polyamines in Paul's Scarlet rose suspension cultures

Polyamine concentrations have been determined at intervals in suspension cultures of Paul's Scarlet rose cells during a culture period of 2 weeks. The mean concentrations of the putrescine, spermidine and spermine in the cells of the inocula were respectively 73, 70 and 13 nmol/g fresh weight. Putrescine at fitst increased with a peak (160 nmol/g) after 6 h, declined to a minimum (14 nmol/g) after 2–3 days, increased to a second peak (180 nmol/g) after 5–6 days, and then declined slowly to the concentration of the inoculum (taken on day 14). Spermidine rose slowly (×2.6) to a broad peak over 3–6 days (180 nmol/g), then declined slowly to the concentration in the inoculum. Spermine showed a rapid increase to a peak (130 nmol/g) after 2–3 days, and then declined rapidly, reaching the inoculum concentration by day 6. In one experiment the three amines showed a minor peak at day 11. Changes in spermine and RNA contents appeared to be correlated. DNA content reached a peak after that of the RNA (day 3) and did not appear to be correlated with the content of putrescine or the polyamines.     

Quantitative Microdialysis: Analysis of Transients and Application to Pharmacokinetics in Brain

The behavior of a microdialysis probe in vivo is mathematically described. A diffusion-reaction model is developed that not only accounts for transport of substances through tissues and probe membranes but also accounts for transport across the microvasculature and metabolism. Time-dependent equations are presented both for the effluent microdialysate concentration and for concentration profiles about the probe. The analysis applies either to measuring the tissue pharmacokinetics of drugs administered systemically, or for sampling of endogenously produced substances from tissue. In addition, an expression is developed for the transient concentration about the probe when it is used as an infusion device. All mathematical expressions are found to be a sum of an algebraic and an integral term. Theoretical prediction of time-dependent probe behavior in brain has been compared with experimental data for acetaminophen administered at 15 mg/kg to rats by intravenous bolus. Plasma and whole striatal tissue samples were used to describe plasma kinetics and to estimate a capillary permeability-area product of 0.07 min-1. Theoretical prediction of transient effluent dialysate concentrations exhibited close agreement with experimental data over 60 min. Terminal decline of the dialysate effluent concentration was slightly overestimated but theoretical concentrations still lay within the 95% confidence interval of the experimental data at 112 min. Microvasculature transport and metabolism play major roles in determining microdialysate transient responses. Extraction fraction (recovery) has been shown to be a declining function in time for five probe operating conditions. High rates of metabolism and/or capillary transport affect the time required to approach steady-state extraction, shortening the time as the rates increase. Conversely, for substances characterized by low permeabilities and negligible metabolism, experimental situations exist that are predicted to have very slow approaches to microdialysis steady state.     

The isometric length-force models of nine different skeletal muscles.

The length-force relations of nine different skeletal muscles in the hindlimb of the cat were determined experimentally, with electrical stimulation of the sciatic nerve as the activation mode. It was shown that the active-, passive-, and total-force patterns varied widely among the muscles. The tibialis posterior (TP), medial and lateral gastrocnemius (MG, LG) and flexor digitorum longus (FDL) had a symmetric active-force curve, whereas the tibialis anterior (TA), peroneus brevis (PB), peroneus longus (PL), extensor digitorum longus (EDL), and soleus (SOL) had an asymmetric curve which exhibits about 25% of the maximal isometric force at extreme lengths. The SOL, EDL, and LG had a low-level passive force which appeared at short muscle length, whereas all other muscles exhibited initial passive force just before the optimal length. The total force was rising quasi-linearly for the SOL, whereas the other muscles exhibited an intermediate plateau about the optimal length. The LG and FDL had a substantial but temporary intermediate dip in the total force as the muscle was elongated past the optimal length. The elongation range of the various muscles also varied, ranging from +/- 15 to +/- 30% of the optimal length. The elongation range was symmetric for the FDL, LG, MG, TP, SOL, and EDL, and asymmetric for the PL, PB, and TA, being -12 to + 17%, -12 to + 17%, and -35 to + 12%, respectively. Two different models which incorporate muscle architecture were successfully fitted to the experimental data of the muscles except for the MG and TA. The architecture of these two muscles is highly nonhomogeneous and contains compartments with two pennation patterns or two different optimal lengths. New models, which add spatially and temporally the individual characteristics of each compartment of the muscles, were constructed for these two muscles. The new models demonstrated high correlation to the experimental data obtained from the MG and TA. It was concluded that the length-force relation varies widely among various skeletal muscles and is probably dependent on the primary function of the muscle in the context of integrated movement; this is a manifestation of architectural factors such as fiber pennation pattern and angle, cross-sectional area, ratio of muscle to tendon length, distribution of the fiber length within the muscle and compartmental pennation.