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PubMed2004

Topical tea tree oil effective in canine localised pruritic dermatitis--a multi-centre randomised double-blind controlled clinical trial in the veterinary practice.

Tea tree oil, a volatile oil, is well known for its broad antibacterial and antifungal activity. A standardised and stabilised 10% tea tree oil cream was tested against a commercial skin care cream (control cream) in the management of canine localised acute and chronic dermatitis. Fifty-seven dogs with clinical manifestations of mostly pruritic skin lesions or alterations, skin fold pyodermas and other forms of dermatitis, corroborated by predominantly positive fungal and bacterial skin isolates, were enrolled by seven practising veterinarians and randomly allocated to two study groups (28:29) and were treated twice daily with a blinded topical preparation. After 10 days of treatment, success rates of 71% for the tea tree oil cream and 41% for the control cream (over-all efficacy documented by the veterinary investigator) differed significantly (p = 0.04), favouring tea tree oil cream treatment. Accordingly on day 10, the tea tree oil cream caused significantly faster relief than the control cream (p = 0.04) for two common clinical dermatitis signs, pruritus (occurring in 84 % of dogs) and alopecia. Only one adverse event was reported in the tea tree oil group (suspected not to be causally related to the study drug) and none in the control cream group. The tested herbal cream appears to be a fast-acting safe alternative to conventional therapy for symptomatic treatment of canine localised dermatitis with pruritus.

Administration, Topical↗

PubMed2003

Efficient tree-matching methods for accurate carbohydrate database queries.

One aspect of glycome informatics is the analysis of carbohydrate sugar chains, or glycans, whose basic structure is not a sequence, but a tree structure. Although there has been much work in the development of sequence databases and matching algorithms for sequences (for performing queries and analyzing similarity), the more complicated tree structure of glycans does not allow a direct implementation of such a database for glycans, and further, does not allow for the direct application of sequence alignment algorithms for performing searches or analyzing similarity. Therefore, we have utilized a polynomial-time dynamic programming algorithm for solving the maximum common subtree of two trees to implement an accurate and efficient tool for finding and aligning maximally matching glycan trees. The KEGG Glycan database for glycan structures released recently incorporates our tree-structure alignment algorithm with various parameters to adapt to the needs of a variety of users. Because we use similarity scores as opposed to a distance metric, our methods are more readily used to display trees of higher similarity. We present the two methods developed for this purpose and illustrate its validity.

Algorithms↗

PubMed2005

[Tree species diversity of tropical montane rain forest in Xishuangbanna, Yunnan].

Tropical montane rain forest (TMR), one of the main forest vegetation types in Xishuangbanna of Yunnan Province, occurs horizontally in the north (TMRF I) and vertically in the south (TMRF II). In order to understand its tree species diversity in different zones, six fixed plots (50 m x 50 m) at different sites in Xishuangbanna were established, two (plots 1 and 2) for TMRF I, and four (plots 3, 4, 5 and 6) for TMRF II. Grid method (10 m x 10 m) was used to record all the individuals with DBH greater than 2.0 cm in each plot, and tree species richness and diversity characteristics along DBH class, as well as changing trend of tree species diversity with increasing sampling area were analyzed. The results showed that the tree stem and species richness in the six plots both declined constantly along the DBH class gradient. For the communities of TMRF I (altitude was 850 1000 m), all indices had no clear trend with the gradient, while for the communities of TMRF II (altitude 1 200 - 2000 m), Shannon-Wiener and Simpson indices declined constantly with gradient, but Pielou's evenness index had the opposite trend. In smaller DBH classes (> or =2 cm, > or =5 cm and > or =10 cm), the tree species richness, diversity, and evenness of the communities of TMRF II were obviously higher than those of the communities of TMRF I, but there was no difference between the communities of TMRF I and TMRF II in larger DBH classes (> or = 20.0 cm, > or =30.0 cm and > or =50.0 cm) . With sampling area increased, the tree species richness, Shannon-Wiener index, Simpson index and Pielou's evenness index of the six plots all had the trend to be smooth when the sampling area increased to 2 000 m2.

Biodiversity↗

PubMed1990

Habitat and temporal partitioning of tree hole Culicoides (Diptera: Ceratopogonidae).

Spring emergence patterns of tree hole Culicoides were examined at 11 geographic locations. Habitat selection was one mechanism of partitioning used by Culicoides. One group (3 species) occupied tree holes with standing water (wet), while the other (7 species) inhabited tree holes without standing water (dry). The wet tree hole species had sustained emergence patterns, emergence maintained over several consecutive weeks. The dry tree hole species had phasic or biphasic emergence lasting fewer days or occurring as 2 short periods. In both dry and wet habitats, species emerged in a temporal sequence. This temporal sequence was disrupted if a species occupied a type of tree hole (wet/dry) from which it did not normally occur.

Animals↗

PubMed1970

Christmas tree allergy: mould and pollen studies.

A history of respiratory or other allergic symptoms during the Christmas season is occasionally obtained from allergic patients and can be related to exposure to conifers at home or in school. Incidence and mechanism of production of these symptoms were studied. Of 1657 allergic patients, respiratory and skin allergies to conifers occurred in 7%. This seasonal syndrome includes sneezing, wheezing and transitory skin rashes. The majority of patients develop their disease within 24 hours, but 15% experience symptoms after several days' delay. Mould and pollen studies were carried out in 10 test sites before, during and after tree placement in the home. Scrapings from pine and spruce bark yielded large numbers of Penicillium, Epicoccum and Alternaria, but these failed to become airborne. No significant alteration was discovered in the airborne fungi in houses when trees were present. Pollen studies showed release into air of weed, grass and tree pollens while Christmas trees were in the house. Oleoresins of the tree balsam are thought to be the most likely cause of the symptoms designated as Christmas tree allergy.

Adolescent↗

PubMed1997

Equivalent tree representation of electrocardiogram using genetic algorithm.

Electrocardiogram (ECG) gives the electrical activity of the heart. The number of data points required to represent the ECG signal is reduced by using a complete-tree representation. This reduced data structure (ECG Tree) is obtained by fitting the ECG signal in a grid structure consisting of both horizontal and vertical lines. The leaf nodes are the points where the vertical grid lines intersect with the ECG signal. These leaf nodes now form the features of the ECG signal. Some of these leaf nodes may be redundant and hence the reduction in the number of leaf nodes and thus optimization of the tree (equivalent tree) is done using a novel technique based on the Genetic Algorithm (GA). In this work, the equivalent tree is formed using GA consisting of four stages. First, from the group of generated leaf nodes various combinations of strings are constructed to form the population. Second, the fitness function is taken as the measure of the vertical distances between two neighbouring leaf nodes in order to evaluate the population with respect to their fitness values. Third, the selection procedure is used to give offsprings based on an assigned threshold value. Finally, crossover and mutation operations are performed repeatedly till an optimized population is obtained. The optimal nodes represent the equivalent tree. The Backpropagation Neural Network as a classifier is used to test the efficacy of the GA in this optimization problem.

Algorithms↗

PubMed2005

Haplotype trees and modern human origins.

A haplotype is a multisite haploid genotype at two or more polymorphic sites on the same chromosome in a defined DNA region. An evolutionary tree of the haplotypes can be estimated if the DNA region had little to no recombination. Haplotype trees can be used to reconstruct past human gene-flow patterns and historical events, but any single tree captures only a small portion of evolutionary history, and is subject to error. A fuller view of human evolution requires multiple DNA regions, and errors can be minimized by cross-validating inferences across loci. An analysis of 25 DNA regions reveals an out-of-Africa expansion event at 1.9 million years ago. Gene flow with isolation by distance was established between African and Eurasian populations by about 1.5 million years ago, with no detectable interruptions since. A second out-of-Africa expansion occurred about 700,000 years ago, and involved interbreeding with at least some Eurasian populations. A third out-of-Africa event occurred around 100,000 years ago, and was also characterized by interbreeding, with the hypothesis of a total Eurasian replacement strongly rejected (P < 10(-17)). This does not preclude the possibility that some Eurasian populations could have been replaced, and the status of Neanderthals is indecisive. Demographic inferences from haplotype trees have been inconsistent, so few definitive conclusions can be made at this time. Haplotype trees from human parasites offer additional insights into human evolution and raise the possibility of an Asian isolate of humanity, but once again not in a definitive fashion. Haplotype trees can also indicate which genes were subject to positive selection in the lineage leading to modern humans. Genetics provides many insights into human evolution, but those insights need to be integrated with fossil and archaeological data to yield a fuller picture of the origin of modern humans.

Emigration and Immigration↗

PubMed2004

Preservation of hippocampal neuron numbers and hippocampal subfield volumes in behaviorally characterized aged tree shrews.

Aging is associated with a decreased ability to store and retrieve information. The hippocampal formation plays a critical role in such memory processes, and its integrity is affected during normal aging. We used tree shrews (Tupaia belangeri) as an animal model of aging, because in many characteristics, tree shrews are closer to primates than they are to rodents. Young and aged male tree shrews performed a holeboard spatial memory task, which permits assessment of reference and working memory. Upon completion of the behavioral measurements, we carried out modified stereological analyses of neuronal numbers in various subdivisions of the hippocampus and used the Cavalieri method to calculate the volumes of these subfields. Results showed that the working memory of aged tree shrews was significantly impaired compared with that of young animals, whereas the hippocampus-dependent reference memory remained unchanged by aging. Estimation of the number of neurons revealed preserved neuron numbers in the subiculum, in the subregions CA1, CA2, CA3, and in the hilus of the dentate gyrus. Volume measurements showed no aging-related changes in the volume of any of these hippocampal subregions, or in the molecular and granule cell layers of the dentate gyrus of tree shrews. We conclude that the observed changes in memory performance in aging tree shrews are not accompanied by observable reductions of hippocampal neuron numbers or hippocampal volume, rather, the changes in memory performance are more likely the result of modified subcellular mechanisms that are affected by the aging process.

Aging↗

PubMed1981

Postnatal modifications of the dendritic tree of cells in the inferior colliculus of the cat. A quantitative Golgi analysis.

Postnatal modifications of dendrites have been quantitatively studied by network analysis of the dendritic tree in the two central nuclei of the inferior colliculus in the cat. This analysis revealed cells with two types of branching patterns suggesting two different modes of growth. The predominant pattern is characterized by dichotomous branching on random segments (DR cells). However, a purely collateral branching pattern is particular to certain cells (CB cells). These two branching patterns were found in both nuclei of the IC in adult and young cats, but the exact significance of these two cell types remains unclear. The dendritic trees of cells in kittens differed from those of the adult cat. Also, the types of modification were different in the two functionally distinct nuclei of the inferior colliculus that we studied. The most dramatic modifications were observed in the dendritic tree of DR cells in the central nucleus, which receives fibers from the auditory nuclei in the brainstem. Two parameters were modified: the mean number of terminal segments and the mean total length of segments. Both parameters increased in the sagittal plane and decreased in the frontal plane. These modifications indicate a reorientation of the dendritic tree in the sagittal plane, along the incoming axons from the auditory nuclei. As these afferents become functionally mature only after birth, this spatial remodeling of the dendrites seems closely related to functional maturation of secondary auditory axons. In the dorsomedial nucleus that receives fibers from the auditory cortices, the dendritic tree of DR cells also undergoes spatial reorientation. This is more evident in the horizontal plane and with respect to the incoming axons. Our results suggest that the characteristic orientation of the dendritic tree of cells observed in the inferior colliculus of the adult cat is established only after the first postnatal weeks. This orientation seems to result from an active process of remodeling concomitant with the functional maturation of afferents, a fact already established for various cell types in the nervous system.

Afferent Pathways↗

PubMed1990

Alpha 2-adrenergic binding sites in the medulla oblongata of tree shrews demonstrated by in vitro autoradiography: species related differences in comparison to the rat.

Alpha 2-adrenergic binding sites in the medulla oblongata of tree shrews and rats were detected and quantified by in vitro-autoradiography with the alpha 2-antagonist 3H-rauwolscine (3H-RAUW). The autoradiographic pattern of the radioligand binding in the tree shrew medulla oblongata resembles that which has been described by others for the human myelencephalon. This pattern coincides well with the occurrence of catecholaminergic structures detected by immunocytochemistry with antibodies against phenylethanolamine-N-methyltransferase and tyrosine hydroxylase. In contrast to the rat, where only the nucleus tractus solitarii and the nucleus dorsalis nervi vagi were labeled, five discrete nuclei specifically bound 3H-RAUW in tree shrews. The highest number of binding sites was detected in the nucleus dorsalis nervi vagi (nX; Bmax: 333 fmoles/mg) and the nucleus tractus solitarii (NTS; 311 fmoles/mg), followed by the nucleus nervi hypoglossi (nXII; 297 fmoles/mg), the nucleus reticularis parvocellularis (FRS; 230 fmoles/mg), and the area of the catecholamine cell groups A1 and C1 (area C1; 202 fmoles/mg). Maximal binding in the two labeled nuclei of the rat was 158 fmoles/mg. The discrete nuclei of the two species also showed different affinities for 3H-RAUW with Kd ranging from 0.17 to 0.83 nM in tree shrews and 1.80 to 1.95 nM in rats. Competition experiments revealed that the radioligand bound specifically to alpha 2-binding sites. In the tree shrew, nX, nXII and the area C1, also have a relatively high affinity for the alpha 1-antagonist prazosin which is a quality of the adrenoceptor subtype alpha 2B. Furthermore, in the area C1, 3H-RAUW binding was inhibited by the dopamine antagonist haloperidol. There are thus species related as well as regional differences with respect to the number, the affinity, and the pharmacological properties of alpha 2-binding sites in the medulla oblongata. In tree shrews, alpha 2-adrenoceptors can be autoradiographically quantified in regions which are not labeled in the rat, although former data predicted the existence of such receptors, e.g., in the area of the adrenaline cell group C1.

Animals↗

PubMed1990

Development of the lateral geniculate nucleus: interactions between retinal afferent, cytoarchitectonic, and glial cell process lamination in ferrets and tree shrews.

We have studied the relationship of retinal afferents, glial cell processes, and neuronal cytoarchitectonics in the lateral geniculate nucleus (LGN) of two species: tree shrews (Tupaia belangeri) and ferrets (Mustela putoris). Both species are relatively immature at birth, allowing the development of these features to be studied in the perinatal period. Retinal afferents, visualized by intraocular injection of a wheat germ agglutinin/horseradish peroxidase conjugate (WGA-HRP), are apparently the first elements of the developing LGN to exhibit a characteristic layered pattern in tree shrews and ferrets. Some radial glia still remain in the LGN of both species as the retinal afferents are in the process of segregating. Glial cell processes were visualized immunohistochemically with antibodies to glial fibrillary acidic protein (GFAP) or vimentin. In both the ferret and tree shrew, layering of glial cell processes is first seen as the overlap of retinal terminal fields diminishes. In the tree shrew LGN, these bands of dense glial cell staining are seen in apparent future cellular layers, whereas in the ferret, glial cell banding appears in interlaminar zones. If one or both eyes are removed at birth in tree shrews (before LGN cell layers are formed), the glial cell pattern seen 1 week later is in accord with the distribution of surviving nerve cells. The glial processes do not appear to invade regions left by degenerating retinal terminals or dying LGN cells. Several days after the appearance of layered glial cell processes (in the tree shrew) or at about the same time as glial layering (in the ferret), the first interlaminar spaces develop between neuronal cells, marking the beginning of cytoarchitectonic lamination, with its distinctive alternating cell-rich and cell-poor zones. Over the next several weeks, LGN neurons in both species continue to segregate into characteristic layers until the final, adult pattern of neuronal lamination is evident; as this process is completed, glial cell lamination disappears. These observations suggest that glial cells may be involved in establishing the neuronal layers that characterize the mature LGN of many species.

Afferent Pathways↗

PubMed2006

A tree-based model for allele-sharing-based linkage analysis in human complex diseases.

By adapting a well-known affected-relative-pair linkage model that can incorporate covariate or sub-phenotype information [Olson, 1999: Am J Hum Genet 65:1760-1769], we have developed a recursive-partitioning (RP) algorithm (tree-based model) for identifying phenotype and covariate groupings that interact with the evidence for linkage. This strategy is designed to identify subgroups of affected relative pairs demonstrating increased evidence for linkage, where subgroups are defined by pair-level or family-level covariates. After growing a full tree, we identified optimal tree size through a form of tree pruning and chose the best covariate at each split by using bootstrap algorithms. Simulation studies showed that power to detect linkage can increase in the presence of gene-environment interactions, depending on the magnitude of the interaction. As expected, however, power can decrease by examining more covariates, despite the pruning to optimize tree size. The RP model correctly identifies tree structure in a large proportion of simulations. We applied the RP model to a dataset of families with bipolar affective disorder (BPAD) where linkage regions on chromosome 18 have been previously identified. Using the all-pairs score in Genehunter, the NPL tests showed no regions with strong linkage evidence on chromosome 18. However, using the RP model, several suggestive regions were found on chromosome 18. Two covariates appeared to influence the degree of linkage: the type II BPAD subtype and a pattern of displaying mania before or after a depressive episode. The RP model has the potential to identify previously unknown gene-environmental interactions; here we have demonstrated the practical utility and potential this new methodology holds.

Algorithms↗

PubMed2001

Structure-function correlation in transient amacrine cells of goldfish retina: basic and multifractal analyses of dendritic trees in distinct synaptic layers.

Amacrine cells generating light-evoked transient ON-OFF responses were stained by intracellular injection of horseradish peroxidase after determining their input-output (voltage response vs. light intensity) profiles. Ten cells specifically having bistratified dendritic trees were analyzed. The cross-sectional area of the dendrites in each sublamina (a and b) of the inner plexiform layer was initially measured. Although some variability was observed, there was no statistically significant overall difference in the cross-sectional areas of the dendritic trees in sublaminae a and b. Also, the amplitudes of the ON and OFF responses, generated by a midrange criterion stimulus, could not be correlated with the cross-sectional areas or the number of branches of the dendrites in sublaminae b and a, respectively. On the other hand, determination of the generalized fractal spectra revealed that the negative (up to -3) and zero-order fractal dimensions of the dendritic trees in sublamina a were consistently higher than those for sublamina b. Furthermore, there was a positive correlation between response amplitude and some part of the generalized fractal dimension in the respective parts of the dendritic trees. It is concluded that dendritic tree characteristics differ in the two halves of the inner plexiform layer and that these can be related to the cells' light-evoked response amplitudes. Furthermore, generalized fractal analysis appears to be a useful method for correlating structure and function in retinal amacrine cells with complex dendritic trees.

Algorithms↗

PubMed2006

Variability in initial spray deposit in apple trees in space and time.

Variation in pesticide residues in space and time has not been investigated systematically in spite of the large variability found at single scales (e.g. between trees or orchards). Information on variability at different scales will support the development of sampling methods and more reliable prediction of residues. Experiments were conducted to quantify the spatiotemporal variability in initial spray deposit on apple leaves and fruit using a substitute tracer (zinc EDTA chelate). Five hierarchical spatial scales were defined as (1) between orchards, (2) between plots within an orchard, (3) between trees within a plot, (4) between zones within a tree and (5) between leaves/fruit within a zone. Similarly, two temporal scales were defined as (1) between applications within a single year and (2) between years. The initial zinc concentration was approximately log-normally distributed; the variability in initial deposit concentration was greater on leaves than on fruit. The average initial zinc deposition was significantly greater in the top and outside zones than in the middle zones within individual trees. The most important scale for driving residue variability is the within-zone unit-to-unit variation, contributing to 71 and 49% of the observed variability for leaf and fruit samples respectively. Variability at other scales was related to the variation in the tree architecture. The results indicated that stratified sampling on the basis of within-tree zone structures, with the effort focused on within-zone sampling, should be used for the determination of pesticide residues.

Chelating Agents↗

PubMed1999

Shear stress distribution in arterial tree models, generated by constrained constructive optimization.

Models of arterial trees are generated by the algorithm of Constrained Constructive Optimization (CCO). Straight cylindrical, binary branching tubes are arranged in an optimized fashion so as to convey blood to the terminal sites of the tree, which are distributed over a predefined area, representing the tissue to be perfused. All terminal segments supply equal flows at a unique terminal pressure, and the radii of parent and daughter segments are related via a bifurcation law. The connective structure and geometry of the model are optimized according to a target function such as total intravascular volume. The shear rate between blood and the vessel walls is computed in each segment and a new method is presented for rescaling a given CCO tree to a desired value of shear rate in the root segment. The effect of viscosity varying with shear rate is evaluated and a new method is presented for rescaling a CCO-tree segment by segment to consistent values of radii and variable viscosity. Shear stress is evaluated for its deviation from being proportional to shear rate and then subjected to various types of analyses. Usually both, shear stress and its variability, are found to be larger in the smaller than in the larger segments of the CCO-model trees. However, it is shown how the shear-stress distribution can be reshuffled between small and large segments when rescaling a CCO tree to obey a different bifurcation law, while its whole geometry remains unchanged and all boundary conditions remain fulfilled. The selection of optimization target is found to drastically affect shear-stress variability within bifurcations, which reaches a distinct minimum if the model is optimized according to intravascular volume. Finally, a rank-analysis of shear stress within each bifurcation shows that only two out of six possible rank patterns actually occur: the parent segment always experiences medium shear stress while minimum shear stress resides mostly in the larger, less frequently in the smaller daughter.

Arteries↗

PubMed2001

Nuclear and mtDNA phylogenies of the Trimeresurus complex: implications for the gene versus species tree debate.

Phylogenies based on mitochondrial DNA (mtDNA) may represent gene trees that may not be congruent with the equivalent species tree. One solution to this problem is to include additional, independent loci from the nuclear genome. Sequence data from the seventh intron of the beta-fibrinogen gene were generated for 25 specimens of vipers, including 8 nominal species of the Trimeresurus complex of Asian pit vipers. Phylogenetic trees were generated using maximum-parsimony and maximum-likelihood methods. The taxonomic level at which the intron provided significant phylogenetic information was examined and the trees were compared to those produced from previously obtained mtDNA cytochrome b sequences. A variety of different approaches (separate analyses, conditional data combination, and consensus) were used in an attempt to provide a sound organismal phylogeny based on both nuclear and mtDNA data sets. We discuss the implications for the gene tree-species tree debate and its particular relevance to medically important organisms.

Animals↗

PubMed2003

Quantitative analysis of intrathoracic airway trees: methods and validation.

A method for quantitative assessment of tree structures is reported allowing evaluation of airway or vascular tree morphology and its associated function. Our skeletonization and branch-point identification method provides a basis for tree quantification or tree matching, tree-branch diameter measurement in any orientation, and labeling individual branch segments. All main components of our method were specifically developed to deal with imaging artifacts typically present in volumetric medical image data. The proposed method has been tested in 343 computer phantom instances subjected to changes of its orientation as well as in a repeatedly CT-scanned rubber plastic phantom width sub-voxel accuracy and high reproducibility. Application to 35 human in vivo trees yielded reliable and well-positioned centerlines and branch-points.

Algorithms↗

PubMed1996

Human hepatitis B virus and hepatocellular carcinoma. I. Experimental infection of tree shrews with hepatitis B virus.

Tree shrews (Tupaia belangeri chinenesis) can be experimentally infected with human hepatitis B virus (HBV) by inoculation with human serum positive for HBV, the experimental infection rate being 55.21%. Successive infections have been passed through five generations among the tree shrews inoculated with HBV-positive sera from the infected animals, the average infection rate being 94.0%. The experimental infection of tree shrews with HBV may be prevented by immunization with hepatitis B vaccine, the protection rate being 88.89%. Standard serum containing HBV at 10(8) CID (chimpanzee infection dose)/ml, was diluted 10(-6), 10(-7), 10(-8), 10(-9), and 10(-10) and produced infection rates of 80.0%, 88.8%, 66.7%, 55.6% and 42.9% respectively. Thus the CID50 in tree shrews may reach a dilution of 10(-9), which shows that tree shrews are sensitive to HBV infection. These results successfully establish tree shrews as a reliable and useful animal model for research on HBV infection and its relation to hepatocarcinogenesis.

Animals↗