974 resultados para Small-world
Resumo:
Statement of purpose: Increased resting energy expenditure following head injury is well documented, but whether this increase extends into rehabilitation and whether this is affected by changes in body composition have not been studied. The aim of this study was to determine whether children attending a rehabilitation program following head injury had altered energy expenditure and body composition. Methods: Measurements of resting energy expenditure by indirect calorimetry were performed in 21 head injured children (mean age 10.2±3.8 years). Measurement of body composition was performed using total body potassium. Results: Measured resting energy expenditure values were widely distributed, ranging from 52.3-156.4% of predicted values, yet the mean percentage predicted using Schofield weight, Schofield weight and height and World Health Organization predictive equations were 97.5%, 97.4% and 98.6%, respectively. Mean percentage of expected total body potassium for weight, height and age for head injured children were 85.1 ± 15.5%, 89.1 ± 14.1% and 86.9 ± 15.9%, thus all showed significant depletion. Conclusions: During rehabilitation, using predictive equations to estimate resting energy expenditure in this group revealed a small bias on average but very large bias at the individual level. Head injured children had altered resting energy expenditure and body composition.
Resumo:
The extrastriate cortex near the dorsal midline has been described as part of an 'express' pathway that provides visual input to the premotor cortex. This pathway is considered important for the integration of sensory information about the visual field periphery and the skeletomotor system, especially in relation to the control of arm movements. However, a better understanding of the functional contributions of different parts of this complex has been hampered by the lack of data on the extent and boundaries of its constituent visual areas. Recent studies in macaques have provided the first detailed view of the topographical organization of this region in Old World monkeys. Despite differences in nomenclature, a comparison of the visuotopic organization, myeloarchitecture and connections of the relevant visual areas with those previously studied in New World monkeys reveals a remarkable degree of similarity and helps to clarify the subdivision of function between different areas of the dorsomedial complex. A caudal visual area, named DM or V6, appears to be important for the detection of coherent patterns of movement across wide regions of the visual field, such as those induced during self-motion. A rostral area, named M or V6A, is more directly involved with visuomotor integration. This area receives projections both from DM/V6 and from a separate motion analysis channel, centred on the middle temporal visual area (or V5), which detects the movement of objects in extrapersonal space. These results support the suggestion, made earlier on the basis of more fragmentary evidence, that the areas rostral to the second visual area in dorsal cortex are homologous in all simian primates. Moreover, they emphasize the importance of determining the anatomical organization of the cortex as a prerequisite for elucidating the function of different cortical areas.
Resumo:
Published results on the inhibitory effects of small cosolutes on adenosine deamination by adenosine deaminase [Kurz. L. C.. Weitkamp, E., and Frieden, C. (1987) Biochemistry 26, 3027-3032; Dzingeleski, G., and Wolfenden, R. (1993) Biochemistry 32, 9143 -9147] have been reexamined. Results for sucrose, dioxane, methanol, and ethanol are shown to be qualitatively consistent with thermodynamic interpretation in terms of molecular crowding effects arising from the occurrence of a minor increase in enzyme volume and/or asymmetry during the kinetic reaction-a conformational transition that could be either preexisting or ligand induced. Direct evidence for the existence of the putative isomeric transition is provided by active enzyme gel chromatography on Sephadex G-100, which demonstrates a negative dependence of enzyme elution volume upon substrate concentration and is therefore consistent with substrate-mediated conformational changes that favor a larger (or more asymmetric) isomeric state of the enzyme. There are thus experimental grounds for adopting the present description of the inhibitory effects of unrelated cosolutes on the kinetics of adenosine deamination by adenosine deaminase in terms of thermodynamic nonideality.
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Henneguya lesteri n. sp, (Myxosporea) is described from sand whiting, Sillago analis, from the southern Queensland coast of Australia. H. lesteri displays a preference for the pseudobranchs and is typically positioned along the afferent blood vessels, displacing the adjoining lamellae and disrupting their normal array, The plasmodia appeared as whitish-hyaline, elliptical cysts (mean dimensions 230 x 410 mum) attached to the oral mucosa lining of the hyoid arch on the inner surface of the operculum. Infections of the gills were also found, in which the plasmodia were spherical, averaged 240 x 240 mum in size and were located on the inner hemibranch margin. The parasites lodged in the gill filament crypts and generated a mild hyperplastic response of the branchial epithelium, In histological sections, the plasmodium wall and adjoining ectoplasm appeared as a finely granulated, weakly eosinophilic layer, Ultrastructurally, this section of the host-parasite interface contained an intricate complex of pinocytotic channels. H. lesteri is polysporic, disporoblastic and pansporoblast forming. Sporogenesis is asynchronous, with the earliest developmental stages aligned predominantly along the plasmodium periphery, and maturing sporoblasts and spores toward the center. Ultrastructural details of sporoblast and spore development are in agreement with previously described myxosporeans. The mature spore is drop-shaped, length (mean) 9.1 mum, width 4.7 mum, thickness 2.5 mum, and comprises 2 polar capsules positioned closely together, a binucleated sporoplasm and a caudal process of 12.6 mum. The polar capsules are elongated, 3.2 x 1.6 mum, with 4 turns of the polar filament. Mean length of the everted filament is 23.2 mum, Few studies have analyzed the 18S gene-of marine Myxosporea. In fact, H. lesteri is the first marine species of Henneguya to be characterized at the molecular level: we determined 1966 bp of the small-subunit (18S) rDNA, The results indicated that differences between this and the hitherto studied freshwater Henneguya species are greater than differences among the freshwater Henneguya species.
Resumo:
A small disturbance in the axisymmetric, bathtub-like flow with strong vorticity is considered and the asymptotic representation of the solution is found. It is shown that if the disturbance is smaller than a certain critical scale, the conventional strong vortex approximation cannot describe the field generated by the disturbance not only in the vicinity of the disturbance but also at the distances much larger than the critical scale. (C) 2001 American Institute of Physics.
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Trypanosome infections are often difficult to detect by conventional microscopy and their pleomorphy often confounds differential diagnosis. Molecular techniques are now being used to diagnose infections and to determine phylogenetic relationships between species. Complete small subunit rRNA gene sequences were determined for isolates of Trypanosoma chelodina from the Brisbane River tortoise (Emydura signata), the saw-shelled tortoise (Elseya latisternum), and the eastern snake-necked tortoise (Chelodina longicollis) from southeast Queensland, Australia. Partial sequence data were also obtained for T. binneyi from a platypus (Ornithorhynchus anatinus) from Tasmania. Phylogenetic relationships between T. chelodina, T. binneyi and other species were examined by maximum parsimony and likelihood methods. The Australian tortoise and platypus trypanosomes did not exhibit any close phylogenetic relationships with those of mammals, reptiles or amphibians, but were closely related to each other, and to fish trypanosomes. This contra-indicates their co-evolution with their vertebrate hosts but does not exclude co-evolution with different groups of invertebrate vectors, notably insects and leeches.
Resumo:
The basal dendritic arbors of 442 supragranular pyramidal cells in visual cortex of the marmoset monkey were compared by fractal analyses. As detailed in a previous study,(1) individual cells were injected with Lucifer Yellow and processed for a DAB reaction product. The basal dendritic arbors were drawn, in the tangential plane, and the fractal dimension (D) determined by the dilation method. The fractal dimensions were compared between cells in ten cortical areas containing cells involved in visual processing, including the primary visual area (Vi), the second visual area (V2), the dorsoanterior area (DA), the dorsomedial area (DM), the dorsolateral. area (DL), the middle temporal area (MT), the posterior parietal area (PP), the fundus of the superior temporal area (FST) and the caudal and rostral subdivisions of inferotemporal cortex (ITc and ITr, respectively). Of 45 pairwise interareal comparisons of the fractal dimension of neurones, 20 were significantly different. Moreover, comparison of data according to previously published visual processing pathways revealed a trend for cells with greater fractal dimensions in higher cortical areas. Comparison of the present results with those in homologous cortical areas in the macaque monkey(2) revealed some similarities between the two species. The similarity in the trends of D values of cells in both species may reflect developmental features which, result in different functional attributes.
Resumo:
Recently, Barrett's esophagus and early adenocarcinomas have been detected increasingly frequently in routine follow-up of patients with gastroesophageal reflux. Although surgery is the treatment of choice, some patients are medically unfit for esophagectomy and, in this case, the only alternative curative therapy is radical chemoradiation therapy. In addition, some patients who present with symptoms have small tumors that cannot be localized accurately using routine imaging techniques. This report describes a series of eight patients with small esophageal cancers in whom the tumors were successfully localized following endoscopic injection of contrast, and treated with chemoradiation therapy. The treatment was successful in seven patients. This method of tumor localization demonstrated that conventional techniques are mostly, unreliable when applied to very early cancers.
Resumo:
Many non-steroidal anti-inflammatory drugs (NSAIDs) which form acyl glucuronide conjugates as major metabolites have shown an antiproliferative effect on colorectal tumors. This study assesses the extent to which rearrangement of an acyl glucuronide metabolite of a model NSAID into beta -glucuronidase-resistant isomers facilitates its passage through the small intestine to reach the colon. Rats were dosed orally with diflunisal (DF), its acyl glucuronide (DAG) and a mixture of rearrangement isomers (iso-DAG) at 10 mg DF equivalents/kg. The parent drug DF appeared in plasma after all doses, with maximum concentrations of 20.5 +/- 2.5, 28.8 +/- 8.3 and 11.0 +/- 1.6 mug DF/ml respectively, obtained at 3.8 +/- 0.3, 3.6 +/- 1.8 and 7.5 +/- 0.9 hr after the DF, DAG and iso-DAG doses respectively. At 48 hr, 16.2 +/- 3.3, 19.8 +/- 0.8 and 42.9 +/- 10.1% of the doses respectively were recovered in feces, with less than or equal to 1% remaining in the intestine. About half of each dose was recovered as DF and metabolites in 48 hr urine: for DF and DAG doses, the majority was in the first 24 hr urine. whereas for iso-DAG doses, recoveries in the first and second 24 hr periods were similar. The results show that hydrolysis of both DAG and iso-DAG, and absorption of liberated DF, occur during passage through the gut, but that these processes occur more slowly and to a lesser degree for iso-DAG. The intrinsic hydrolytic capacities of various intestinal segments (including contents) towards DAG and iso-DAG were obtained by incubating homogenates under saturating concentrations of DAG/iso-DAG at 37 degreesC. Upper small intestine, lower small intestine, caecum and colon released 2400, 3200, 9200 and 22800 mug DF/hr/g tissue plus contents respectively from DAG substrate, and 18, 10, 140 and 120 mug DF/hr/g tissue plus contents respectively from iso-DAG substrate. The much greater resistance of iso-DAG to hydrolysis appears attributable to its resistance to beta -glucuronidases. The data suggest that in rats dosed with DF, DAG excreted in bile would be substantially hydrolysed in the small intestine and liberated DF reabsorbed, but that portion which rearranges to iso-DAG would likely reach the colon. (C) 2001 Elsevier Science Inc. All rights reserved.
Resumo:
A commercially available smoke-water solution (Seed Starter (R)) stimulated the germination of caryopses and intact florets of Avena fatua L. The solution was most effective when diluted (5-50%) and presented to intact or dehulled grain that had received a short period of dry after-ripening. It was less effective when applied at full strength or to grains that had been freshly harvested. The same stimulatory effect was observed in par-fly after-ripened caryopses of nine different wild oat biotypes obtained from three different cropping regions of the world. When freshly harvested caryopses were re-tested with the commercial solution (100%) for just 7 days prior to placement on to distilled water, a much higher germination percentage was possible than seen with continuous smoke-water incubation. The stimulatory ability of smoke water was more closely matched to that of gibberellic acid than to potassium nitrate, which had little or no effect on freshly harvested caryopses. The smoke-water solution (5-100%) was tested on the germination of 18 other cool temperate arable weed species. All monocotyledonous species tested (viz. Avena sterilis ssp. ludoviciana L., Alopecurus myosuroides, Sorghum halepense, Phalaris paradoxa) responded positively, while those of the dicotyledonous species were either strongly stimulated (greater than or equal to 40% stimulation Malva neglecta), moderately stimulated (greater than or equal to 20% stimulation Galium aparine, Veronica persica), slightly stimulated (Polygonum persicaria, P pennsylvanicum, Fallopia convolvulus), unaffected (P. aviculare, Sinapis arvensis, Heracleum sphondylium, Angelica sylvestris, Mercurialis annua, Veronica hederifolia) or inhibited (Lamium purpureum). The optimal concentrations required to stimulate germination of the monocotyledonous species were similar to those observed for A. fatua (5-10%). However, for the dicotyledonous species slightly stronger solutions were required (10-20%). When the unaffected species were retested using a 10-day pre-chilling treatment, smoke water showed a small promotive response in three (S. arvensis, P. aviculare and V hederifolia) of the six species. When four different smoke-water solutions (Seed Starter (R), Regen 2000 (R), charred-wood solution and wheat-straw solution) were tested on two representative species (A. fatua and M. neglecta), three formulations were effective in promoting the germination of both species, while the fourth (charred-wood solution) was only active on A. fatua. The active concentrations were different for the four solutions. Three solutions were active in the 2-20% dilution range, while the fourth (Regen 2000 (R)) was only active in the 1-2% dilution range and was inhibitory at higher concentrations. These observations are discussed in the context that smoke may play an important ecological role in the management and control of introduced weeds in native and arable communities.