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  • Cell & Developmental Biology  (8)
  • General Chemistry  (6)
  • Secale cereale  (5)
  • Insulin  (3)
  • 1
    ISSN: 1432-0428
    Keywords: Insulin ; despentapeptide insulin ; deshexapeptide insulin ; negative cooperativity ; insulin demerisation ; lipogenesis ; insulin binding ; insulin metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The C-terminus of the insulin B chain is essential for dimerisation and expression of negative cooperativity. In order to evaluate the possible physiological role of these phenomena, we have studied the properties in vivo and in vitro of despentapeptide insulin (B 26–30 deleted), derived from beef insulin, and deshexapeptide insulin (B25–30 deleted), derived from pork insulin. These materials do not dimerise and have 15% and 0% retention of negative cooperativity respectively. Lipogenesis potencies in rat adipocytes were: despentapeptide insulin 19.9±0.3%; deshexapeptide insulin 19.9±1.5%. Binding potencies in adipocytes were: despentapeptide insulin 22.6±7.8%; deshexapeptide insulin 13.2±3.3%. Metabolic clearance rates were reduced compared to insulin (insulin = 19.1±0.9; despentapeptide insulin = 9.7±0.8; deshexapeptide insulin = 6.4±0.6ml·min−1·kg−1 at plasma concentration 0.5 nmol/l). Hypoglycaemic potencies were reduced for both analogues (40% and 30%) when calculated on the basis of plasma concentration although both analogues and insulin were equally effective at lowering plasma glucose concentration in equimolar doses. Plasma half-disappearance time was prolonged (despentapeptide insulin=7.3±0.5; deshexapeptide insulin=9.1±0.2 min). Both analogues were full agonists and conformed to the general relationship between in vitro and in vivo properties seen with a wide range of modified insulins. They resemble other analogues with modifications which reduce receptor affinity without impairing dimerisation or negative cooperativity. The results do not support a physiological role for dimerisation or negative cooperativity.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Insulin ; insulin analogues ; glucose metabolism ; euglycaemic clamp ; insulin action ; hepatoselectivity ; glucose production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Insulin analogues with relatively greater effect on hepatic glucose production than peripheral glucose disposal could offer a more physiological approach to the treatment of diabetes mellitus. The fact that proinsulin exhibits this property to a minor degree may suggest that analogues with increased molecular size may be less able than insulin to obtain access to peripheral receptor sites. Covalent insulin dimers have previously been shown to possess lower hypoglycaemic potencies than predicted by their in vivo receptor binding affinities. Reduced rates of diffusion to peripheral target tissues-might be an explanation for the lower in vivo potency compared to insulin. To test the relative hepatic and peripheral effects of covalent insulin dimers, glucose clamp procedures with D-[3-3H] glucose tracer infusions were used in anaesthetised greyhounds to establish dose-response curves for rates of hepatic glucose production and glucose disposal with insulin, NαB1, NαB′ 1,-suberoyl-insulin dimer, and NεB29, NεB′ 29,-suberoyl-insulin dimer. With NαB1, NαB′ 1,-suberoyl-insulin dimer molar potencies relative to insulin were 68%, (34–133) (mean and 95% fiducial limits), for inhibition of hepatic glucose production and 14.7%, (10.3–20.9) for glucose disposal. With NεB29,NεB′ 29,-suberoyl-insulin dimer potencies were 75%, (31–184) and 2.5%, (1.5–4.3), for inhibition of hepatic glucose production and for glucose disposal, respectively. The demonstration that both dimers exhibit a significantly greater effect on glucose production than on glucose disposal supports the suggestion that analogues with increased molecular size may exhibit reduced ability to gain access to peripheral target cells.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-6849
    Keywords: B chromosome ; DNA sequence composition ; fluorescencein situ hybridization ; repetitive sequence ; Secale cereale ; translocations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Fluorescencein situ hybridization (FISH) has been used to analyse the structure of the rye B chromosome. Genomicin situ hybridization (GISH) demonstrates the high level of overall similarity between A and B chromosomes of rye, as well as the presence of a number of specific sequences. The B-specific repeat families D1100 and E3900 have been analysed in terms of their physical location and possible contiguity. Rye Bs contain members of the rye-specific dispersed repetitive family R173, as well as centromeric regions similar to those of the As. The B chromosomes analysed in our study lack detectable rDNA sequences. Anomalous results have been obtained with a number of subtelomeric repetitive probes from rye. Bs usually lack these sequences, but evidence is presented that in some cases A–B translocation events may relocate such sequences from the As to the Bs. These data are discussed in the context of current models for the origin of the B chromosome.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-6849
    Keywords: B chromosomes ; genomicin situ hybridization ; nuclear architecture ; Secale cereale ; Triticum aestivum cv ; Lindström
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The B chromosomes (Bs) of rye (Secale cereale) have been studied at interphase in terms of their chromatin organization, patterns of nuclear disposition and physical association in plants with two, three, and four Bs. The study was made in the Lindström strain of hexaploid wheat, which carries the rye Bs as an addition line, byin situ hybridization with a B-specific probe and by genomicin situ hybridization (GISH) with rye genomic DNA, enabling whole chromosome painting. Repetive sequences common to the As and Bs of rye allow for visualization of the rye B at interphase in the wheat background. A B-specific probe enables the orientation of two or more Bs to be determined, and the combination of both probes used together gives information on the disposition of the Bs and on their patterns of physical association within the nucleus. The Bs form linear ‘strings’, and the ends of their long arms, which can be detected by the B-specific probe, are usually located within the hemisphere of the nucleus that has the least condensed chromatin. There is dose-dependent association, and even numbers (2B, 4B) have a greater preference for association than odd ones (3B).
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 97 (1996), S. 65-72 
    ISSN: 1573-6857
    Keywords: Secale cereale ; rye ; B chromosomes ; inbred lines ; pairing ; pollen mitosis ; transmission genotypes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract B chromosomes from an experimental population of the Japanese JNK strain of rye, isogenic for its Bs, have been backcrossed into twelve different inbred lines. The experiment is a way of studying the effects of the Bs against a range of different homozygous A chromosome backgrounds. This publication deals with pairing effects of both the As and the Bs, and their interactions, and with pollen mitosis. At meiosis there is a genotypic component to B effects, and they do not appear to act solely through a physical disturbance within the nucleus. In pollen the Bs are always present in more than 50% of the grains regardless of their pairing behaviour during meiosis; this result fits with a ‘parasitic’ model of the activity of rye Bs.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromosome research 5 (1997), S. 177-181 
    ISSN: 1573-6849
    Keywords: B chromosomes ; interphase chromosome arrangement ; meiosis ; Secale cereale ; Triticum aestivum cv. Lindstro¨m
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Probes for B chromosome-specific sequences in the distal region of the long arm of the rye B have been used to investigate the interphase arrangement of the Bs in rye and in hexaploid wheat. The Lindstro¨m strain of wheat carries the rye Bs as additions. The number of in situ signals in nuclei with two, three and four Bs is often less than the maximum B number, and it seems that the Bs may be grouped together in various ways rather than being randomly dispersed throughout the nucleus. The degree of physical association is greater in rye than in the alien wheat background. The results are discussed in relation to the pairing and recombination preferences of the Bs in rye and in Lindstro¨m wheat.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Genetica 92 (1994), S. 149-154 
    ISSN: 1573-6857
    Keywords: Secale cereale ; rye ; B-chromosomes ; fitness ; inbred lines ; parasitic Bs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract B-chromosomes from an experimental population of the Japanese JNK strain of rye, isogenic for its Bs, have been backcrossed into twelve different inbred lines. The experiment provides a way to study the effects of the Bs against a range of homozygous A-chromosome backgrounds. This publication deals with vigour and fertility: it shows that the rye Bs fit a parasitic model, and that they interact in their effects with the A-chromosome background genotype.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-136X
    Keywords: Glycogen ; Hepatocyte ; Insulin ; 13C NMR ; Rainbow trout, Oncorhynchus mykiss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This study, using 13C nuclear magnetic resonance spectroscopy showed enrichment of glycogen carbon (C1) from 13C-labelled (C1) glucose indicating a direct pathway for glycogen synthesis from glucose in rainbow trout (Oncorhynchus mykiss) hepatocytes. There was a direct relationship between hepatocyte glycogen content and total glycogen synthase, total glycogen phosphorylase and glycogen phosphorylase a activities, whereas the relationship was inverse between glycogen content and % glycogen synthase a and glycogen synthase a/glycogen phosphorylase a ratio. Incubation of hepatocytes with glucose (3 or 10 mmol·1-1) did not modify either glycogen synthase or glycogen phosphorylase activities. Insulin (porcine, 10-8 mol·1-1) in the medium significantly decreased total glycogen phosphorylase and glycogen phosphorylase a activities, but had no significant effect on glycogen synthase activities when compared to the controls (absence of insulin). In the presence of 10 mmol·1-1 glucose, insulin increased % glycogen synthase a and decreased % glycogen phosphorylase a activities in trout hepatocytes. Also, the effect of insulin on the activities of % glycogen synthase a and glycogen synthase a/glycogen phosphorylase a ratio were more pronounced at low than at high hepatocyte glycogen content. The results indicate that in trout hepatocytes both the glycogen synthetic and breakdown pathways are active concurrently in vitro and any subtle alterations in the phosphorylase to synthase ratio may determine the hepatic glycogen content. Insulin plays an important role in the regulation of glycogen metabolism in rainbow trout hepatocytes. The effect of insulin on hepatocyte glycogen content may be under the control of several factors, including plasma glucose concentration and hepatocyte glycogen content.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 81 (1969), S. 1006-1006 
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 215 (1986), S. 99-105 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Rats were treated daily for 9 days with 100, 50, or 25 mg/kg phenytoin i.p. This treatment resulted in a significant increase in the thickness of the connective tissue capsules of the liver, spleen, and pancreas, and of the subepithelial connective tissue of the mesentery but not the epicardium or visceral pleura of the lung where exposure to the drug was via the vascular route. Many areas of connective tissue growth exhibited obvious proliferation of fibroblasts and in some areas contained seemingly large numbers of macrophages and an increase in vascularity. It was demonstrated by electron microscopy that the macrophages occasionally were seen in intimate contact with the fibroblasts.Our observations clearly showed that intraperitoneal exposure of visceral connective tissues of the rat to phenytoin rapidly resulted in a dose-related proliferation of that tissue. The presence of numerous macrophages leads to the suggestion that macrophage-derived growth factor could be responsible for the increased growth.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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