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  • 1
    ISSN: 1420-9098
    Keywords: Tetraponera ; bamboo ; ants ; nest flooding ; water removal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Southeast Asian antTetraponera sp. nearattenuata F. Smith inhabits internodes of large bamboo species that it shares with symbiotic pseudococcids. It finds access to this nesting habitat via small holes made by wood-boring insects. During heavy rain, runoff water collects in these punctured internodes. TheTetraponera workers remove the water by ingesting it, walking to the entrance hole, and regurgitating it to the outside. In this way, they 1) reduce the danger of colony members drowing, 2) enable their symbionts to feed also on the internode floor, and 3) prevent excessive growth of microbes in the nest.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Endothelial cells ; very low density lipoprotein subfractions ; diabetes mellitus ; atherosclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The very low density lipoprotein (VLDL) fraction was isolated from 11 normolipidaemic Type 1 (insulin-dependent) diabetic patients in good to fair glycaemic control and from 11 age-, sex- and race-matched, non-diabetic, control subjects. The rate of receptor-mediated degradation by human endothelial cells was significantly greater (p〈0.02) for the total VLDL fraction isolated from diabetic patients compared to control subjects and averaged 1008±300 and 717±150 ng·mg cell protein−1·16 h−1, respectively. The total VLDL fraction was separated into three subfractions: VLDL-I, Sf 100–400 (Sf = Svedberg units); VLDL-II, Sf 60–100; VLDL-III, Sf20–60. Rates of receptor-mediated degradation of VLDL-I and VLDL-II isolated from diabetic patients were significantly greater than the comparable subfraction isolated from control subjects and averaged 1023±279 vs 361±122 (p〈0.01) and 433±70 vs 294±70 ng·mg cell protein−1·16 h−1 (p〈0.03), respectively. Rates of receptor-mediated degradation of the V-III subfraction isolated from the two groups did not differ significantly. There were no significant differences in the chemical composition or in the plasma concentrations of the VLDL subfractions isolated from diabetic patients compared to control subjects. There was a significant increase in the apoprotein E content of VLDL-I (p〈0.01) and VLDL-II (p〈0.05) isolated from diabetic patients. There was a significant increase in the ratio of apoprotein C compared to apoprotein E (p〈0.03) in VLDL-I isolated from control subjects compared to the diabetic patients. There were no significant differences in the apoprotein composition of VLDL-III isolated from the two groups.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Glycated haemoglobin A1 ; plasma glucose ; diabetic retinopathy ; risk factor ; receiver operating characteristic (ROC) analysis ; Pima Indians
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Among Pima Indians with Type 2 (non-insulin-dependent) diabetes mellitus the relationships between glycated haemoglobin (HbA1), fasting or 2-h post-load plasma glucose and diabetic retinopathy were examined by cross-sectional and prospective analyses, and the strengths of the associations were directly compared by receiver operating characteristic analysis. In the cross-sectional analysis, HbA1, fasting and 2-h plasma glucose were each significantly related to retinopathy among 789 diabetic subjects by separate logistic models. In a stepwise multiple logistic model in which HbA1, fasting and 2-h plasma glucose were included, HbA1 was selected as having the strongest association with retinopathy and neither fasting nor 2-h plasma glucose contributed significantly to the model once HbA1 was entered. Similarly, in the prospective analysis, HbA1, fasting and 2-h plasma glucose all predicted retinopathy in 227 diabetic subjects by separate proportional-hazards models. In a stepwise proportional-hazards model with HbA1, fasting and 2-h plasma glucose available to the model, HbA1 was again selected as having the strongest association with the incidence of retinopathy, and neither fasting nor 2-h plasma glucose significantly added to the prediction of retinopathy. A receiver operating characteristic analysis was used to determine if HbA1 was statistically significantly better than fasting or 2-h plasma glucose in assessing the risk for retinopathy. In neither the cross-sectional nor the prospective data did the area under the receiver operating characteristic curve for HbA1 differ significantly from that for fasting or 2-h plasma glucose (p〉0.05 for each). In conclusion, HbA1, an integrated measure of blood glucose concentration over a period of 2–3 months, is slightly more closely associated with the prevalence and incidence of diabetic retinopathy than a single blood glucose determination. However, the differences between HbA1 and fasting or 2-h plasma glucose in assessing the association with or the risk for retinopathy are not significant.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric radiology 23 (1993), S. 355-356 
    ISSN: 1432-1998
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 3-year-old boy with a radiographic finding of an isolated invaginated Meckel's diverticulum is presented. The abnormality simulates a polypoid filling defect in the distal small bowel on barium examination. This particular manifestation of Meckel's diverticulum is very rare and has been reported only once previously. This article re-emphasizes the need to think about this possibility when a polypoid filling defect is seen in the distal small bowel. At the time laparotomy was performed, the abnormality had progressed into a triple intussusception, a rare surgical finding.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Molecular engineering 3 (1993), S. 43-59 
    ISSN: 1572-8951
    Keywords: Heteropolymolybdates ; heteropolytungstates ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The chemistry of polynuclear oxometalate anions is dominated by molybdenum and tungsten in their highest oxidation state. During the past twenty years this class of compounds has attracted much attention because of their variable applications, e.g. as reagents in analytical procedures, as industrial catalysts and as potential anticancer drugs. In order to obtain model systems for the investigation of the catalytic activity of heteropolyanions we have synthesized and structurally characterized some organo derivatives of polyoxoanions. We secondly focus on Sb(III) and Bi(III) heteropolytungstates to examine the important influence of the unshared electron pair on the resulting structures and properties. Some of these compounds may be regarded as supramolecular aggregates showing inclusion phenomena. In 9 two [SbW9O33]9− anions are linked by a set of six sodium ions forming a nearly planar hexagon. The sodium ions are enveloped by an oxygen cage formed by terminal oxygen atoms of the polyanions and by water molecules. Furthermore, the four anions [Sb2W22O74(OH)2]12−, [Sb2W20Fe2O70(H2O)6]8−, [Sb2W20Co2O70(H2O)6]10− and [Bi2W20Fe2O68(OH)2(H2O)6]6− (in10, 11, 12, 13) may be regarded as transition metal complexes of novel [Sb2W20O70]14− or [Bi2W20O70]14− anions which are serving as ligands. The octahedral coordination sphere of each transition metal is formed by three oxygen atoms of the anion and completed by three water molecules. The Sb(III) heteropolyanion, [Na2Sb8W36O132(H2O)4]22− in (14) includes two sodium and four antimony ions besides four water molecules. Each anion consists of four β-B-SbW9-Keggin fragments linked together by four SbO4-groups, incorporating two sodium and four water molecules effecting an additional connection of the subunits.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1612-1112
    Keywords: Ligand exchange chromatography ; Chiral mobile phase ; Enantiomer separation ; Natural pterins ; Colpidium campylum ; Astasia longa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of the D and L enantiomers of biopterin and neopterin has been achieved by ligand exchange chromatography using a reversed phase column with a mobile phase containing D-phenylalanine as chiral modifier and Cu(II) as the metal ion. This successful separation has enabled the identification of natural pterins present in various protozoans by comparison with authentic, optically pure compounds. D-monapterin and D-neopterin were identified in the ciliate protozoanColpidium campylum. L-biopterin has been found, for the firs time, in a flagellate protozoan,Astasia longa.
    Type of Medium: Electronic Resource
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