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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 24 (1991), S. 4408-4422 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Langmuir 8 (1992), S. 2913-2920 
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    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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  • 4
    ISSN: 1420-9098
    Keywords: Tetraponera ; bamboo ; ants ; colony structure ; polydomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The colony structure of the bamboo-inhabiting SE-Asian pseudomyrmecine antTetraponera sp. PSW-80 nearattenuata F. Smith was investigated at the Ulu Gombak Field Studies Centre, Selangor, West-Malaysia. Based on the dissection of 54 stem internodes from 12 different culms of the large bambooGigantochloa scortechinii Gamble and on the mapping of three colonies, the following demographic characteristics emerge. The colonies are monogynous but highly polydomous (at least up to 36 internodes and up to 9 stems occupied) and very populous for a pseudomyrmecine not involved in an ant-plant mutualism. One completely censused colony had 6953 adult workers and 2079 alates (adults plus pupae). The single queen suppresses gyne development in her own “nest” and, to a lesser extent, in other “nests” within the same stem. The overall numerical sex ratio was 0.96∶1 (females:males), the investment sex ratio, 2.93∶1, i.e., almost exactly the 3∶1 ratio expected for a monogynous outbred hymenopteran in which the colony queen also produces all the male offspring. Brood is distributed to all other nest chambers from the queenright chamber. The symbiotic pseudococcids (Kermicus wroughtoni Newstead) are present in all inhabited internodes, with small early instar individuals prevailing numerically by far over the larger stages. The rieht well secluded honeydew supply within the internode and the efficient architectural protection provided by the internode wall (access usually only through a 2 × 3 mm-hole) allowT. sp. PSW-80 to reach an unusually large colony size without being an aggressive and protective plant mutualist like other members of its subfamily with similar demographic features.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0428
    Keywords: Type 2 (non-insulin-dependent) diabetes mellitus ; VLDL metabolism ; LDL metabolism ; human macrophages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The very low- and low-density lipoprotein fractions were isolated from 16 normolipidaemic Type 2 (non-insulin-dependent) diabetic patients in good to fair glycaemic control and from corresponding age-, sex-, and race-matched, non-diabetic control subjects. Rates of cholesteryl ester synthesis averaged 268±31 vs 289±40 pmol 14C-cholesteryl oleate·-mg cell protein−1·20 h−1 for very low- and 506±34 vs 556±51 pmol 14C-cholesteryl oleate·mg cell protein−1·20 h−1 for low-density lipoproteins isolated from the Type 2 diabetic patients and control subjects, respectively, when they were incubated with human macrophages. A group of approximately one-third of the patients was selected for separate analyses because very low-density lipoproteins isolated from these patients did stimulate more cholesteryl ester synthesis when incubated with macrophages. There were no significant differences in the lipid composition of the lipoproteins isolated from the three groups of subjects. The relative proportion of apoprotein C to apoprotein E was significantly decreased (p〈0.002) in the very low-density lipoproteins from diabetic patients and was further decreased in samples from these selected diabetic patients. The apoprotein C-I content of very low-density lipoproteins isolated from diabetic patients was increased compared to control subjects and was further increased in samples from the selected diabetic patients (p〈0.02). There were no significant differences in the proportions of apoproteins C-III-0, C-III-1, or C-III-2 among the three groups. These studies suggest that in normolipidaemic Type 2 diabetic patients, the apoprotein composition of VLDL is abnormal and this may alter VLDL macrophage interactions and thus contribute to the increased prevalence of atherosclerosis in diabetic patients.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Keywords: Type 1 (insulin-dependent) diabetes mellitus ; diabetic nephropathy ; 5′ insulin gene polymorphism ; heredity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent data suggest genetic contributions to the microvascular complications of Type 1 (insulin-dependent) diabetes mellitus. Most research has focused on the HLA region, and the potential role of other genetic loci has not been adequately explored. We examined the possible relationship between DNA polymorphisms in the region 5′ to the insulin gene on chromosome 11 and diabetic nephropathy. This was done by comparison of those diabetic patients homozygous for class 1 alleles at the 5′ insulin gene polymorphism locus to 1/3 heterozygotes in a well-characterized series of 324 insulin-requiring diabetic patients from the Wisconsin Epidemiologic Study of Diabetic Retinopathy. Proteinuria (defined as ≥0.3 g protein/l urine), was used as suggestive evidence for diabetic nephropathy. Hypertension, a frequent associated finding in diabetic patients with nephropathy, was defined as a blood pressure greater than 140/90 or a history of previous treatment of hypertension. The two genotypically defined groups did not differ from each other in regard to sex ratio, age at diagnosis, age at examination, duration of diabetes, body mass, HbAlc or C-peptide. The 1/1 group had a higher prevalence of proteinuria, 29% as compared to 16.2 % in other genotypes (p〈0.05). There was no significant difference in the frequency of hypertension between the two genotypic groups. This finding suggests that the 5′ insulin gene polymorphism may be associated with risk for nephropathy, but the pathophysiologic mechanism remains unclear.
    Type of Medium: Electronic Resource
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  • 7
    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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  • 8
    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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  • 9
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The stable carbon and oxygen isotopic compositions of the massive coralPorites lobata collected from the Gulf of Eilat, Red Sea, in May 1987 were measured along the vertical growth axis. The isotopic compositions show annual periodicity. The variations along the isotopic profile, compared with the X-radiography, indicate that the high-density bands are enriched in18O and deposited during the season of lowest water temperature (winter). In contrast, the low-density bands are depleted in18O and deposited during the warmest seawater temperatures (summer). The stable carbon and the oxygen isotopic ratios are negatively correlated with a shift in phase. During the season of higher water temperatures and light intensity values (summer), the skeleton is depleted in18O and enriched in13C and vice versa for the winter time. The shift between the carbon and the oxygen isotopic curves reflects the shift between the seasonal light intensities and seasonal temperature variations in the shallow water. The oxygen isotope ratio was used to detect the seasonal variations in seawater temperatures. The coral aragonitic skeleton is depleted in18O compared to apparent equilibrium with ambient seawater. The disequilibria range from (ca.) -3.10‰ to -3.50‰ with an average value of 3.40‰. The isotope fractionation behavior during skeleton precipitation is discussed in light of the environmental variables.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1440
    Keywords: Tobacco-specific nitrosamines ; Toxicokinetics ; Genotoxicity ; Systemic effects ; Primary cells ; Detection of DNA damage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An ex vivo model to detect nonspecific DNA damage in different rat tissues has been developed and employed to study systemic properties of tobacco-specific N-nitrosamines. One hour after treatment of rats with the carcinogens, primary, intact cells were isolated from various organs. Viability of the cells was monitored by trypan blue exclusion. Genotoxicity was determined by alkaline elution, in situ nick translation or microgel electrophoresis. We found that oral application of 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces genotoxic effects in the liver (3.125–50 mg/kg), whereas N-nitrosonornicotine (NNN) is only moderately active (50–100 mg/kg). Furthermore, oral administration of NNK, NNN, and of N-nitrosodimethylamine (NDMA), induces DNA damage in the nasal cavity. In peripheral blood lymphocytes genotoxicity of NDMA (〈 2 mg/kg), but not of NNK (50 mg/kg), was observed. NDMA and NNK are just as genotoxic in the liver when administered by inhalation as orally (effective doses: 0.1–1 and 50 mg/kg, respectively). For human cancer, these results indicate that in addition to the susceptibilities in local organs (oral cavity after snuff dipping and lung after tobacco smoke inhalation), these nitrosamines also pose a risk systemically for more remote organs.
    Type of Medium: Electronic Resource
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