Laboratory studies in cross-species lung transplantation

The lack of sufficient suitable human donor lungs for the many patients requiring pulmonary transplantation as life-saving therapy for end-stage lung diseases has generated extensive interest in cross-species lung transplantation. Ethical concerns and those of animal rights advocates have prompted studies of nonprimate species as potential solid organ donors for humans. This paper provides an overview of some of the laboratory studies of cross-species pulmonary transplantation performed over the past 20 years and focuses, in particular, on more recent work (from our laboratory and others) in the area of porcine-to-primate pulmonary xenotransplantation.     

Age and ethnicity affect the risk and outcome of focal segmental glomerulosclerosis

In patients with proteinuria, African-American (AA) ethnicity is reported to be a risk factor for focal segmental glomerulosclereosis (FSGS) and its progression to end-stage renal disease (ESRD). We reviewed our single-center experience to determine the probability of FSGS and its progression to ESRD based on ethnicity and age at presentation in children with proteinuria with or without nephrotic syndrome. Proteinuria without systemic disease or acute glomerulonephritis was the presenting feature in 17% (236/1,403) of children in the renal patient database of Texas Children's Hospital, Baylor College of Medicine. Histopathological diagnoses were established in 107 of 236 patients (45%). FSGS was identified in 65 patients, accounting for 28% of all patients with proteinuria and 61% of patients who underwent renal biopsy. FSGS was more prevalent in AA (45%) than in non-AA patients (22%) (P=0.001), and AA patients with FSGS were older at presentation (12.7+/-4.4 years) than non-AA patients (5.6+/-4.6 years) (P<0.001). Among patients who underwent renal biopsy, increasing age at presentation increased the probability of having FSGS in AA but not non-AA patients (P=0.04). Five-year actuarial renal survival of FSGS was worse in AA (8%) than in non-AA patients (31%) (P=0.01). These data suggest an increased risk and worse outcome of FSGS in AA compared with non-AA children.     

Multiple Na,K-ATPase Subunits Colocalize in the Brush Border of Mouse Choroid Plexus Epithelial Cells

(1) Background: The unusual accumulation of Na,K-ATPase complexes in the brush border membrane of choroid plexus epithelial cells have intrigued researchers for decades. However, the full range of the expressed Na,K-ATPase subunits and their relation to the microvillus cytoskeleton remains unknown. (2) Methods: RT-PCR analysis, co-immunoprecipitation, native PAGE, mass spectrometry, and differential centrifugation were combined with high-resolution immunofluorescence histochemistry, proximity ligase assays, and stimulated emission depletion (STED) microscopy on mouse choroid plexus cells or tissues in order to resolve these issues. (3) Results: The choroid plexus epithelium expresses Na,K-ATPase subunits α1, α2, β1, β2, β3, and phospholemman. The α1, α2, β1, and β2, subunits are all localized to the brush border membrane, where they appear to form a complex. The ATPase complexes may stabilize in the brush border membrane via anchoring to microvillar actin indirectly through ankyrin-3 or directly via other co-precipitated proteins. Aquaporin 1 (AQP1) may form part of the proposed multi-protein complexes in contrast to another membrane protein, the Na-K-2Cl cotransporter 1 (NKCC1). NKCC1 expression seems necessary for full brush border membrane accumulation of the Na,K-ATPase in the choroid plexus. (4) Conclusion: A multitude of Na,K-ATPase subunits form molecular complexes in the choroid plexus brush border, which may bind to the cytoskeleton by various alternative actin binding proteins.     

Structural study of titanium oxide films synthesized by ion beam-assisted deposition

The application of titanium dioxide (TiO(2)) films as surgical implant coatings for antibiotic attachment depends crucially on their available surface area and thus their surface morphology and crystallinity. Here, we report our fabrication of high Wenzel ratio TiO(2) films targeted to increase the film surface area using the ion beam-assisted deposition (IBAD) technique at high-deposition temperatures (approximately 610 degrees C). The modulation of the films' surface morphology was accomplished by varying the chemical identity of the concurrent ion beams bombarded on the films during the e-beam evaporation process. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to investigate the surface morphology of the as-deposited films. X-ray diffractometry (XRD) revealed that these nanocrystalline films primarily consist of anatase phase TiO(2). Wenzel ratio, the ratio of the actual surface area to the projected area, of IBAD films prepared with argon, oxygen, and nitrogen ion beams was measured to be 1.52, 1.31 and 1.49, respectively. The effect of the differences in chemical reactivity and ion size of these three type ion beams are discussed to explain the present results.     

Evolution of the cranial computed tomography scan in child abuse

Computed tomography (CT) scans obtained at the time of clinical presentation have occasionally been reported to be normal in children with history and findings of significant abusive head injury. We have retrospectively observed abnormalities in "normal" scans of some similar children. We have also seen abnormalities develop on serial scanning. To determine how frequently these situations occur, we reviewed charts of 34 children with a final diagnosis of child abuse who also had cranial CT scans performed. Their CT scans were retrospectively reviewed by a pediatric radiologist. Eleven (11/34) CT scans had initially been interpreted as normal. Four (4/11) of these had been reinterpreted during the hospitalization as abnormal, affecting medical (1) and legal (3) outcome. Repeat scanning in three of the remaining seven resulted in surgical drainage of a subdural effusion (1) and affected legal outcome (2). Four of the seven initial scans felt normal throughout the hospitalizations were judged abnormal on retrospective review. This evaluation was confirmed in the two rescanned. Initial CT interpretation most often failed to appreciate changes in parenchymal density and small amounts of falcine or cortical subdural blood. Subsequent scans also showed evolving effusions and infarcts. Changes were noted in 1 1/2 to 5 days. The CT scan frequently shows subtle changes in the immediate posttrauma period. If the child does not recover promptly, subsequent scans frequently result in significant changes in clinical and legal management.     

Heat conduction by liquid helium II in capillary tubes. IV. Mutual friction under pressure

We report measurements of supercritical heat conduction in liquid helium II at pressures above the vapor pressure. The measurements were made in glass capillary tubes of diameter 50.5 and 366.8 m in the temperature range from 1.2 to 2.1 K. As in our previous results at the vapor pressure, a clear distinction can be made between two regimes in which the average separation of vortex lines is either comparable with or larger than the size of the flow channel. In the wider tube, at high relative velocities v between the superfluid and normal component, where the vortex spacing is small, a modified form of Gorter-Mellink mutual friction F _sn is observed which varies as F_sn=A_snv(v–v₀)². The coefficient A increases with pressure, and its variation with T/T(p) is in fairly good agreement with Schwarz ' microscopic theory of superfluid turbulence. However, the absolute magnitude of A is in general larger than in Schwarz ' theory and also larger than most other experimental values. In the narrower tube the measurements are all in the regime where the vortex spacing is comparable with the tube size, and they do not agree with the predictions of the Gorter-Mellink law. At present, the data cannot be analyzed quantitatively in the terms of the vortex line density, because B, the vortex line scattering coefficient, is not known at high pressures.Preparation of this paper was supported by a U.S. National Science Foundation grant DMR 7901073 and by a UK Science Research Council Senior Fellowship (DFB).SRC Senior Fellow.     

Algorithms for search trees on message passing architectures

In this paper we describe a new algorithm for maintaining a balanced search tree on a message-passing MIMD architecture; the algorithm is particularly well suited for implementation on a small number of processors. We introduce a (2^B-2, 2^B) search tree that uses a bidirectional ring of O(log n) processors to store n entries. Update operations use a bottom-up node-splitting scheme, which performs significantly better than top-down search tree algorithms. The bottom-up algorithm requires many fewer messages and results in less blocking due to synchronization than top-down algorithms. Additionally, for a given cost ratio of computation to communication the value of B may be varied to maximize performance. Implementations on a parallel-architecture simulator are described     

Anaerobic oxidation of methane: mechanisms, bioenergetics, and the ecology of associated microorganisms

Microbially mediated anaerobic oxidation of methane (AOM) moderates the input of methane, an important greenhouse gas, to the atmosphere by consuming methane produced in various marine, terrestrial, and subsurface environments. AOM coupled to sulfate reduction has been most extensively studied because of the abundance of sulfate in marine systems, but electron acceptors otherthan sulfate are more energetically favorable. Phylogenetic trees based on 16S rRNA gene clone libraries derived from microbial communities where AOM occurs show evidence of diverse, methanotrophic archaea (ANME) closely associated with sulfate-reducing bacteria, but these organisms have not yet been isolated as pure cultures. Several biochemical pathways for AOM have been proposed, including reverse methanogenesis, acetogenesis, and methylogenesis, and both culture-dependent and independent techniques have provided some clues to howthese communities function. Still, questions remain regarding the diversity, physiology, and metabolic restrictions of AOM-related organisms.     

Prediction of simultaneous contrast between map colors with Hunt's model of color appearance

The objective of this research was development of a quantitative model of simultaneous contrast (induction) to aid selection of sets of easily identified map colors. The model is an extension of R. W. G. Hunt's model of color appearance. Contrasts between central and proximal colors were used to adjust Hunt's lightness, relative redness-greenness, and relative yellowness-blueness measures. Human subject responses to CRT displays in an experiment were analyzed to produce a set of rules for selecting map colors. Rather than predict average perceptions for central/proximal color combinations, acknowledgment was made of the inherent variability in map readers' perceptions of color by developing generalized perception buffers that accounted for at least 90% of test subject responses. The task of selecting colors that will not be confused once they appear with numerous proximal colors on a map thus becomes a task of selecting colors that do not have buffers that overlap in color space. © 1996 John Wiley & Sons, Inc.     

Postmortem pH, Muscle, and Refrigerated Storage Effects on Ability of Vacuum-Packaged Pork to Bloom

ABSTRACT: Effects of pH, muscle, and storage time on the ability of vacuum-packaged pork chops to bloom were investigated. Low pH samples exhibited more change in color measures during the 30 min blooming period than did the medium and high pH samples. The low pH sample bloomed more rapidly and to a greater extent than medium and high pH samples. Among the 3 muscles, Longissimus had the highest, while Semimembranosus had the lowest a^* value and hue angle changes. Overall, refrigerated storage of vacuum packaged pork for 7 d or more resulted in more efficient blooming when pH was low. The ability of vacuum-packaged pork to rebloom is necessary for the meat to regain the consumer-expected pink-red color after opening the vacuum bag.