Anatomic distribution of pulmonary vascular compliance

Presson, Robert G., Jr., Said H. Audi, Christopher C. Hanger, Gerald M. Zenk, Richard A. Sidner, John H. Linehan, Wiltz W. Wagner, Jr., and Christopher A. Dawson. Anatomic distribution ofpulmonary vascular compliance. J. Appl.Physiol. 84(1): 303-310, 1998.Previously, thepressure changes after arterial and venous occlusion have been used tocharacterize the longitudinal distribution of pulmonary vascularresistance with respect to vascular compliance using compartmentalmodels. However, the compartments have not been defined anatomically.Using video microscopy of the subpleural microcirculation, we havemeasured the flow changes in ~40-µm arterioles and venules aftervenous, arterial, and double occlusion maneuvers. The quasi-steadyflows through these vessels after venous occlusion permitted anestimation of the compliance in three anatomic segments: arteries >40µm, veins >40 µm, and vessels <40 µm in diameter. We foundthat ~65% of the total pulmonary vascular compliance was in vessels<40 µm, presumably mostly capillaries. The transient portions ofthe pressure and flow data after venous, arterial, and double occlusionwere consistent with most of the arterial compliance being upstreamfrom most of the arterial resistance and most of the venous compliancebeing downstream from most of the venous resistance.

     

Does diet in Celtic Sea fishes reflect prey availability?

Feeding preferences of Celtic Sea fishes were investigated using a database of stomach content records, collected between 1977 and 1994. The diet of cod Gadus morhua, hake Merluccius merluccius, megrim Lepidorhombus whiffiagonis, whiting Merlangius merlangus and saithe Pollachius virens changed markedly as the animals grew larger, and although large predators generally chose larger bodied prey, the variability of prey sizes consumed also increased. Large predators continued to select small, low value, benthic prey (e.g. Callionymus spp. and Trisopterus spp.) which were easier to catch, rather than larger, more energy lucrative pelagic prey (e.g. mackerel Scomber scombrus), even though these pelagic prey‐fishes were nearly always available and were often very abundant. Stock estimates of the International Council for the Exploration of the Sea and U.K. groundfish survey catches were used as indices of prey abundance. Blue‐whiting Micromesistius poutassou and other small pelagic fishes (Argentina spp. and clupeoids) were identified as being particularly important, and were consumed by some predators more often than would be expected given the abundance of these prey in the environment. There was no evidence for density‐dependent feeding by predators on mackerel and only hake exhibited density‐dependent feeding on horse‐mackerel. Hake, cod and megrim consumed more blue‐whiting when this prey was at higher abundance in the environment. In choosing what prey to consume, predators must balance costs and benefits, considering the quality of prey and the energy expended during search, capture and handling.     

A detailed analysis of primary feather moult in the Common Starling Sturnus vulgaris– new feather mass increases at a constant rate

During moult, the rate that protein can be synthesized and used to grow new feathers must be a critical factor influencing the quality of new plumage. However, the rate that new feather mass accrues during moult has not been assessed in detail. To estimate this, the increase in length of each of the nine primary feathers (P1–P9) in 16 captive Common Starlings Sturnus vulgaris was measured at weekly intervals throughout moult. The rate of increase in length was similar for all primary feathers except P9, which increased more slowly. After completion of moult, these feathers were plucked, accurately measured and weighed. The distribution of mass along the length of each primary was assessed. Using these data, I estimated the rate that mass had increased for each feather during moult. For each individual primary, mass increased at a steady rate until almost fully grown. The rate of increase in mass was least for P1 and greatest for P9. The number of feathers growing concurrently decreased as moult progressed. The net result was that total new primary feather mass increased at a steady rate throughout most of moult (linear regression between start of growth of P2 and end of growth of P8; r ² = 0.991). Retrospective conversion of feather lengths into moult score showed that the increase in score was not linear. It was greatest early in moult and decreased as moult progressed. A scoring system that factors in distribution of mass within and between feathers may provide a more physiologically relevant measure of the progress of moult.     

Thermal stability: a means to assure tertiary structure in therapeutic proteins.

To be both safe and effective, a therapeutic product must have the correct chemical structure and be free of harmful contaminants. Structure in protein therapeutic products, however, implies not only the correct sequence of amino acids (primary structure) but also the proper folding of that amino acid chain in three-dimensional space (tertiary structure). This work is part of a general strategy to develop a battery of physico-chemical methods that could give assurances of structure (and hence function) in formulated therapeutic proteins in the absence of in vivo data. It focuses on recombinant human growth hormone (rhGH), a well-characterized therapeutic protein, and examines the utility of thermodynamic parameters in assessing its tertiary structure. Resistance of solutions of formulated rhGH to thermal denaturation was followed using Fourier Transform Infrared Spectroscopy (FTIR) by observing decreases in total helicity and increases in intermolecular beta-sheet formation. Under conditions known to induce changes in the intra-molecular ionic and H-bonding patterns stabilizing the tertiary structure but not affecting the protein's secondary structure or global fold, we have observed upwards of a 12 degrees C shift in the melting temperature of the protein. Furthermore, our results indicated that the T(m) of unfolding of rhGH was sensitive to much more subtle changes in the protein structure. Thus, resistance to thermal denaturation may well be a useful means to measure structure in formulations of well-characterized therapeutic proteins.     

IMPACTS OF COMMERCIAL WHALE WATCHING ON MALE SPERM WHALES AT KAIKOURA, NEW ZEALAND

Abstract Male sperm whales are the basis for a commercially important whale-watching industry at Kaikoura, New Zealand. We examined the influence of whale-watching boats and aircraft over three years using observations from an independent research boat and from shore. We employed an information-theoretic approach to determine which factors were necessary to explain variation in blow interval, time at surface, and time to first click. In almost all analyses, models required the inclusion of the presence of the research boat or whale-watching boats or airplanes. The only exception was the model explaining variation in blow intervals observed from shore, which required only season. We also analyzed spatial behavior at the surface. Resident whales changed direction significantly more in the presence of whale-watching boats compared to encounters with only the research boat present. No such difference was observed for encounters with aircraft. Our results thus indicate that sperm whales off Kaikoura respond to whale-watching activities, although these changes are small and most likely not of biological importance. However, resident whales responded less to these activities compared to transient whales, possibly indicating habituation and, more importantly, the need to monitor continued activities closely.     

USING PHYLOGENETIC TREES TO STUDY SPECIATION AND EXTINCTION

One tool in the study of the forces that determine species diversity is the null, or simple, model. The fit of predictions to observations, good or bad, leads to a useful paradigm or to knowledge of forces not accounted for, respectively. It is shown how simple models of speciation and extinction lead directly to predictions of the structure of phylogenetic trees. These predictions include both essential attributes of phylogenetic trees: lengths, in the form of internode distances; and topology, in the form of internode links. These models also lead directly to statistical tests which can be used to compare predictions with phylogenetic trees that are estimated from data. Two different models and eight data sets are considered. A model without species extinction consistently yielded predictions closer to observations than did a model that included extinction. It is proposed that it may be useful to think of the diversification of recently formed monophyletic groups as a random speciation process without extinction.     

Field preservation of marine invertebrate tissue for DNA analyses

Successful preservation of tissue samples is a prerequisite for long field studies in remote areas. However, there is little published information concerning field preservation of marine invertebrate tissues for DNA analyses. This omission is significant because marine biodiversity is centered in the Indo-Pacific, where immediate DNA analysis is often impossible. Consequently, we used an assay based on polymerase chain reaction (PCR) to examine the effect of five storage solutions and three temperature regimens on the degradation of DNA from four common classes of marine invertebrates (Anthozoa, Gastropoda, Polychaeta, and Scyphozoa). Control samples were cryopreserved. Storage solution and the type of tissue preserved were the best predictors of preservation success. The length of time in storage and the storage temperature also affected the preservation of DNA. A field test demonstrates that a solution of dimethylsulfoxide and sodium chloride (DMSO-NaCl) preserves a wide range of tissues for DNA analyses and is very simple to use in remote field locations.     

Nodulation patterns of actinorhizal plants in the family rosaceae

Patterns of nodulation, growth, andFrankia — host specificity have not been well characterized for the actinorhizal genera in the family Rosaceae because of the scarcity ofFrankia isolates from these taxa. Furthermore, the few isolates available from actinorhizal Rosaceae have consistently failed to nodulate plants from the host genus. In a series of experiments, species of rosaceousDryas, Cowania, Cercocarpus, Fallugia, andPurshia were inoculated withFrankia isolates, crushedDryas actinorhizae, and neoglacial soils to ascertain whether any of these inocula would effectively induce nodulation. Neoglacial soils from Alaska and Canada nodulated not only the localDryas drummondii, but alsoCercocarpus betuloides, Cowania mexicana andPurshia tridentata from distant and ecologically diverse locales as well as nonrosaceous, actinorhizal species ofAlnus, Elaeagnus, Myrica, andShepherdia. But of eightFrankia isolates, including two fromPurshia tridentata and one fromCowania mexicana, none were able to induce nodulation onPurshia orCowania species. Globular, actinorhizae-like nodules incapable of acetylene reduction were produced onC. betuloides inoculated withFrankia isolates. Crushed nodule suspensions fromDryas drummondii nodulated rosaceousCowania, Dryas andPurshia, as well as non-rosaceousElaeagnus, Myrica, andShepherdia species. Nodules produced by inoculation ofCowania mexicana andPurshia tridentata with crushed, dried nodule suspensions fromDryas drummondii reduced acetylene to ethylene, indicating nitrogenase activity for these nodulated plants. These data suggest that a similar microsymbiont infects the actinorhizal genera in the family Rosaceae.     

Comprehensive investigation of a structural variant in a bi-specific,N-and C-terminal Fc-fusion molecule,and its monitoring with LC-MS based method

There is an increasing interest in the generation of Fc-fusion molecules to exploit the effector functions of Fc and the fusion partner, towards improving the therapeutic potential. The Fc-fusion molecules have unique structural and functional attributes that impart various advantages. However, the manufacturing of Fc-fusion molecules possesses certain challenges in the biopharmaceutical development. The fusion of unnaturally occurring two or more domains in a construct can pose problems for proper folding and are prone to aggregation and degradation. Reshuffling of disulfide bridges represents a posttranslational event that affects folding. This can play a critical role in the correct structure of a molecule and leads to structural heterogeneity in biotherapeutics; it may also impact the in vivo biological activities, safety, and efficacy of the biopharmaceutical. Our work presents an investigation case of a doublet band, as observed only in nonreducing sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE) for a bi-specific, N- and C-terminal Fc-fusion molecule. Other characterization and orthogonal methods from the analytical panel did not indicate the presence of two distinct species, including the orthogonal CE-SDS (Caliper Lab Chip GXII). Therefore, it was necessary to determine if the phenomenon was an analytical artifact or a real variant of our Fc-fusion molecule. With the comprehensive mass spectrometry-based characterization, we were able to determine that the doublet band was related to the reshuffling of one disulfide bridge in one of the fused domains. Our work illustrates the application of nonreducing peptide mapping by mass spectrometry to characterize and identify disulfide variants in a complex N- and C-terminal Fc-fusion molecule, and further adoption to monitor the disulfide structural variants in the intermediate process samples to drive the manufacturing of a consistent product with the desired quality attributes.