Granular-cell tumor of the breast. A cytologic, immunohistochemical and ultrastructural study of two cases

Two primary granular-cell tumors of the breast are reported. Cytologically and histologically, these tumors had the classic features of small, eccentrically located nuclei and numerous periodic acid-Schiff-positive cytoplasmic granules. The characteristic cytologic features were best appreciated in touch imprints, not in frozen sections. Immunohistochemically, the tumors demonstrated diffuse cytoplasmic staining for S-100 protein but negative staining for myoglobin. The significance of these immunohistochemical staining characteristics, particularly in evaluating the possible histogenesis of these tumors, is discussed. The ultrastructural features of these two tumors are also presented and compared to findings reported by other investigators.     

Electromyography of pongid shoulder muscles III. Quadrupedal positional behavior

Electromyographic (EMG) recordings were taken from 14 shoulder muscles (or major parts of them) in a gorilla, a chimpanzee and an orangutan as they stood quadrupedally and tripedally, descended from elevated substrates, crutch-walked, and progressed quadrupedally on inclined and level substrates. In the African apes, low potentials commonly (but not always) occurred in the sternocostal pectoralis major, anterior deltoid, supraspinatus and subscapularis muscles during quadrupedal stance. The quadrupedal orangutan always exhibited low potentials in the pectoralis major muscle and EMG activity commonly occurred in her supraspinatus and subscapularis muscles. Quiescent tripedal stances were not accompanied by striking changes in EMG patterns from those which characterized quadrupedal stances. Per contra, eccentric loadings of the forelimb during descents from elevated substrates generally recruited notable EMG activity in the deltoid, supraspinatus and, to a lesser extent, infraspinatus muscles of the three pongid apes. The pectoralis major and caudal serratus anterior muscles were much more active in Pongo and Pan during these descents. Supportive segments of quadrupedal locomotive cycles were generally accompanied by EMG activity in the pectoralis major, intermediate and posterior deltoid and supraspinatus muscles. The intermediate and posterior deltoid muscles were characteristically active during pre-release of the hand and early swing phase. The cranial trapezius and supraspinatus muscles also may act during early swing phase. We conclude that the pectoralis major and perhaps the supraspinatus and subscapularis might serve regularly as postural muscles during static terrestrial quadrupedalism in pongid apes. The lack of dramatic differences between the EMG patterns exhibited during fist-walking versus knuckle-walking indicates that an evolutionary transformation from a shoulder complex like that of Pongo to ones like Pan or vice versa need not entail major changes in myological features.     

Subject-specific finite element model of the pelvis: development, validation and sensitivity studies

A better understanding of the three-dimensional mechanics of the pelvis, at the patient-specific level, may lead to improved treatment modalities. Although finite element (FE) models of the pelvis have been developed, validation by direct comparison with subject-specific strains has not been performed, and previous models used simplifying assumptions regarding geometry and material properties. The objectives of this study were to develop and validate a realistic FE model of the pelvis using subject-specific estimates of bone geometry, location-dependent cortical thickness and trabecular bone elastic modulus, and to assess the sensitivity of FE strain predictions to assumptions regarding cortical bone thickness as well as bone and cartilage material properties. A FE model of a cadaveric pelvis was created using subject-specific computed tomography image data. Acetabular loading was applied to the same pelvis using a prosthetic femoral stem in a fashion that could be easily duplicated in the computational model. Cortical bone strains were monitored with rosette strain gauges in ten locations on the left hemipelvis. FE strain predictions were compared directly with experimental results for validation. Overall, baseline FE predictions were strongly correlated with experimental results (r2=0.824), with a best-fit line that was not statistically different than the line y=x (experimental strains = FE predicted strains). Changes to cortical bone thickness and elastic modulus had the largest effect on cortical bone strains. The FE model was less sensitive to changes in all other parameters. The methods developed and validated in this study will be useful for creating and analyzing patient-specific FE models to better understand the biomechanics of the pelvis.     

Rampant horizontal transfer and duplication of rubisco genes in eubacteria and plastids

Previous work has shown that molecular phylogenies of plastids, cyanobacteria, and proteobacteria based on the rubisco (ribulose-1,5- bisphosphate carboxylase/oxygenase) genes rbcL and rbcS are incongruent with molecular phylogenies based on other genes and are also incompatible with structural and biochemical information. Although it has been much speculated that this is the consequence of a single horizontal gene transfer (of a proteobacterial or mitochondrial rubisco operon into plastids of rhodophytic and chromophytic algae), neither this hypothesis nor the alternative hypothesis of ancient gene duplication have been examined in detail. We have conducted phylogenetic analyses of all available bacterial rbcL sequences, and representative plastid sequences, in order to explore these alternative hypothesis and fully examine the complexity of rubisco gene evolution. The rbcL phylogeny reveals a surprising number of gene relationships that are fundamentally incongruent with organismal relationships as inferred from multiple lines of other molecular evidence. On the order of six horizontal gene transfers are implied by the form I (L8S8) rbcL phylogeny, two between cyanobacteria and proteobacteria, one between proteobacteria and plastids, and three within proteobacteria. Alternatively, a single ancient duplication of the form I rubisco operon, followed by repeated and pervasive differential loss of one operon or the other, would account for much of this incongruity. In all probability, the rubisco operon has undergone multiple events of both horizontal gene transfer and gene duplication in different lineages.      

Using remote sensing image texture to study habitat use patterns: a case study using the polymorphic white-throated sparrow (Zonotrichia albicollis)

Aim Ecological factors that vary along spatial scales can greatly influence the outcome of evolution. However, often it is difficult for researchers to identify significant ecological variables that might be associated with the geographical distribution of phenotypes and genotypes in nature. In this paper, we use remote sensing image texture analyses to investigate breeding territories of the white‐throated sparrow (Zonotrichia albicollis), a polymorphic passerine species that has been shown to segregate spatially according to morph. Our aim was to examine how an integrative measure of landscape feature, such as image texture, could be used to distinguish subtle differences in habitat use and, presumably, habitat selection. Location A population of white‐throated sparrows located 1.5 miles east of the Cranberry Lake Biological Station in the Adirondack Mountains of St Lawrence County, New York, was used in this study; the study site itself was approximately 1 km². Methods We analysed 27 territories (16 white males; 11 tan males) to determine if image texture can be used to distinguish differences in vegetation and structure in territories of the two colour morphs. First (variance)‐ and second (homogeneity)‐order image texture measurements with three different window sizes were derived using the green, red, and near infrared bands of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. Texture was then placed into t‐tests to determine statistical differences between the territories of the two male morphs. Results Significant differences between the territories of the two morphs were found in both variance and homogeneity texture measures in the red and green ASTER bands in all three window sizes. There were no differences with any near infrared texture measures. Main conclusions Examination of first‐ and second‐order statistical measures indicated that the territories of tan males have significantly more spectral variance than the territories of white males, while white males’ territories are significantly more homogeneous. These findings are consistent with the previous finding of the morphs settling in ‘high’ and ‘low’ neighbour density habitats that differ with respect to the amount of useable area on their borders. Previous study has also suggested that white and tan male territories differ according to overall landscape structure, not vegetation composition. Therefore, we suggest that red and green spectra may be more useful when examining differences in territory structure and possibly territory quality of similar edge‐type species. Our results suggest that image texture is a useful tool for ecological and evolutionary modelling of the distributions of phenotypes/genotypes across landscapes.     

Partial incubation during egg laying reduces eggshell microbial loads in a temperate‐breeding passerine

Incubation prior to clutch completion may be adaptive if it maintains egg viability by inhibiting eggshell microbial growth, thus reducing the likelihood that the embryo becomes infected. To test this hypothesis, we examined the effect of partial incubation during egg laying on eggshell microbial loads in eastern bluebirds Sialia sialis breeding at a temperate‐zone site. We sampled eggshell microbes prior to and following four days of exposure to either partial incubation during the laying period or ambient environmental conditions without incubation (experimental eggs). Microbial colony counts declined significantly for eggs left in the nest during the laying period but did not vary significantly for eggs exposed to ambient conditions. Initial microbial loads were more similar to those previously reported from tropical than temperate environments, and microbes from potentially pathogenic groups were detected on 88% of first‐laid eggs on the day of laying. Egg viability was maintained when eggs were held indoors for four days without incubation but declined sharply thereafter. Our results suggest that partial incubation during egg laying may enhance egg viability in eastern bluebirds by reducing eggshell microbial loads; these effects appear stronger than those usually reported from the temperate zone.