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  • 1980-1984  (8)
  • 1970-1974  (2)
  • 1960-1964
  • Crassulacean acid metabolism  (4)
  • insulin  (4)
  • Life and Medical Sciences  (2)
  • 1
    ISSN: 1432-0428
    Keywords: Intrasplenic rat pancreas transplantation ; insulin ; glucagon ; adipose tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Proliferation of adipose tissue adjacent to intrasplenic transplants of whole isogeneic neonatal rat pancreas has consistently been noted. In this study over a period of 18 months there was a progressive increase in the amount of fatty tissue in the vicinity of surviving transplants. Immunohistochemistry demonstrated the presence of insulin, glucagon, somatostatin and pancreatic polypeptide within islet cells in long term grafts. Electron microscopy demonstrated a close association between islets and lipid droplets. Ductal elements within the transplants survived and showed close association with endocrine cells, but exocrine pancreatic tissue degenerated rapidly. Radioimmunoassay of extracts from surviving transplants in isogeneic rats confirmed the presence of high levels of insulin and glucagon after transplantation. In contrast, allogeneic intrasplenic transplants of rat pancreas failed to survive and showed no evidence of adipose tissue proliferation. Furthermore, isogeneic intrasplenic transplants of both adult rat fat and adrenal gland also failed to demonstrate adipocyte proliferation. It would appear that the presence of both adipocytes and pancreatic endocrine cells, particularly B cells, are required for the proliferation of adipocytes at the graft site.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Arterial ; lipid ; insulin ; streptozotocin ; immunoassay ; atherosclerosis ; glucose ; diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé L'incorporation du D-glucose-U-14C dans les lipides des artèresin vitro était plus grande (p〈0.025) chez les témoins que chez les rats traités à la streptozotocine (65 mg/kg). Une corrélation positive et significative entre cet effet et les taux de l'insuline immunoréactive du plasma a été réalisée, bien qu'il n'y ait aucune corrélation avec les taux du glucose sanguin. On suggère que le taux de l'insuline circulant dans l'animal est important par le fait qu'il modifie le métabolisme des lipides des artères indépendamment des changements dans les lipides du sérum.
    Abstract: Zusammenfassung Die Inkorporation von D-U-14C-Glucose in die Lipide der Arterien warin vitro bei den Kontrolltieren höher (p 〈 0,025) als bei den mit Streptozotozin (65 mg/kg) behandelten Ratten. Eine signifikant positive Korrelation konnte zwischen diesem Effekt und dem immunologisch reaktiven Plasmainsulin gefunden werden, obgleich keine Korrelation mit den Blutzuckerwerten bestand. Es wird angenommen, daß die Menge des im Tier zirkulierenden Insulins wesentlich ist, um den arteriellen Lipidmetabolismus unabhängig von den Veränderungen der Serumlipide zu beeinflussen.
    Notes: Summary D-glucose-U-14C incorporation into arterial lipidsin vitro was greater (p〈0.025) in control than in streptozotocin-treated (65 mg/kg) rats. A significant positive correlation between this effect and the plasma immunoreactive insulin levels was achieved, although there was no correlation with the blood glucose levels. It is suggested that the state of circulating insulin in the animal is important in modifying arterial lipid metabolism independent of changes in serum lipids.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: GIP ; insulin ; glucose ; fasting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The plasma GIP response to an oral 50 g glucose tolerance test has been compared in eight non-obese human subjects after 12 and 36 h of fasting. Basal plasma GIP and basal plasma insulin concentrations were similar after 12 and 36 h of fasting. Basal blood glucose was lower after 36 h fasting than after 12 h fasting (P〈0.0125). After 36 h fasting the oral glucose tolerance test stimulated higher blood glucose concentrations at 60, 90 and 120 min (p〈0.0125) and higher plasma insulin concentrations at similar time points (p〈0.05), but stimulated plasma GIP concentrations were similar after 12 and 36 h fasts. These findings show that the increased insulinotrophic effect of oral glucose after 36 h fasting in nonobese subjects is not due to an associated augmentation of the glucose-induced GIP response.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 9 (1973), S. 457-460 
    ISSN: 1432-0428
    Keywords: Diabetes ; insulin ; starvation ; liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ability of the liver to metabolise insulin in response to varying blood insulin levels was studied using normally fed, starved and streptozotocin diabetic rats. Insulin clearance by the livers of fasted and diabetic rats was significantly increased compared with normal fed controls. Administration of insulin to diabetic animals prior to liver perfusion, or an increase in the concentration of the hormone in the perfusion medium used for normal livers resulted in a significant decrease in clearance. The percentage uptake of insulin during single passage through the livers of starved and diabetic animals was significantly greater than normal.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2048
    Keywords: Crassulacean acid metabolism ; Carbon dioxide fixation ; Circadian rhythm ; Kalanchoë
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 14CO2 was applied repeatedly at 3- to 6-h intervals toKalanchoë daigremontiana leaves during continuous light of differing irradiances. The circadian rhythm in net CO2 uptake in gasexchange measurements and its disappearance at high irradiances was confirmed by oscillating rates of14CO2 incorporation. At 10–30 W m-2 a markedly circadian oscillation in the14CO2-uptake rate was measured; with increasing energy fluence rate the oscillation levelled off at a constant high uptake rate. The labelling patterns obtained during the 10 min of14CO2 fixation indicated that the rhythm of CO2 exchange is the consequence of a rhythmic behaviour in the C4 pathway of CO2 fixation. During the mininum of14CO2 uptake no C4 products were labelled; however, substantial amounts of label were transferred to C4 products during the peaks of14CO2 uptake. Metabolism of C3 and C4 products was also studied in pulsechase experiments at different points of the circadian cycle. In bright light (100 W m-2), when the14CO2 uptake was constantly high, the transfer of label into C4 products (malic acid) was high in spite of the fact that the malate pool is known to be reduced to a permanently low level under these conditions. This led us to the conclusion that it is not the capacity of the phosphoenolpyruvatecarboxylase-mediated CO2 fixation but rather the storage of malic acid in the vacuole that is disturbed under bright-light conditions when the circadian oscillation levelled off.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2048
    Keywords: Carbon dioxide exchange ; Crassulacean acid metabolism ; Kalanchoë ; Leaf water relations ; Phosphoenolpyruvate carboxylase ; Transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gas exchange, leaf water relations, malate content and phosphoenolpyruvate (PEP) carboxylase activity in crude extracts were examined for circadian rhythmicity in the crassulacean acid metabolism plant Kalanchoë daigremontiana. At low irradiance (20 W m-2) the rhythm in CO2 uptake continued for several days with a period length of approx. 22 h, whereas the transpiration rhythm was no longer apparent after 24 h. This shows that the CO2 rhythm in continuous light (LL) is not under stomatal control. Circadian oscillations in malate content were detectable for up to 72 h in LL but were of much reduced amplitude. This was reflected in the changes in leaf water relations, which quickly damped after transfer to LL. The activity of PEP carboxylase assayed immediately after extraction showed a rhythmicity for at least 18 h, but after 36 h, values from different plants were scattered. We suggest that the CO2-uptake rhythm is primarily the result of endogenous changes in the activity of PEP carboxylase, which competes to varying degrees with ribulose-1,5-bisphosphate carboxylase for CO2.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2048
    Keywords: Circadian rhythm ; Crassulacean acid metabolism ; Kalanchoë
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gas exchange in K. blossfeldiana shows a circadian rhythm in net CO2 uptake and transpiration when measured under low and medium irradiances. The period length varies between 21.4 h at 60 W m-2 and 24.0 h at 10 W m-2. In bright light (≧80 W m-2) or darkness there are no rhythms. High leaf temperatures result in a fast dampening of the CO2-uptake rhythm at moderate irradiances, but low leaf temperatures can not overcome the dampening in bright light. The rhythm in CO2 uptake is accompanied by a less pronounced and more rapidly damped rhythm in transpiration and by oscillations in malate levels with the amplitude being highly reduced. The oscillations in starch content, usually observed to oscillate inversely to the acidification in light-dark cycles, disappear after the first cycle in continuous light. The balance between starch and malate levels depends in continuous light on the irradiance applied. Leaves show high malate and low starch content at low irradiance and high starch and low malate in bright light. During the first 12 h in continuous light replacing the usual dark period, malate synthesis decreases with the increasing irradiance. Up to 50 W m-2 starch content decreases; at higher irradiances it increases above the values usually measured at the end of the light period of the 12:12 h light-dark cycle.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2048
    Keywords: CO2 dark fixation ; Crassulacean acid metabolism ; Kalanchoë ; PEP-carboxylase ; Temperature (PEP-carboxylase)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Net CO2 dark fixation of Kalanchoë daigremontiana varies with night temperature. We found an optimum of fixation at about 15° C; with increasing night temperature fixation decreased. We studied the temperature dependence of the activity of phosphoenolpyruvate (PEP)-carboxylase, the key enzyme for CO2 dark fixation. We varied the pH, the substrate concentration (PEP), and the L-malate and glucose-6-phosphate (G-6-P) concentration in the assay. Generally, lowering the pH and reducing the amount of substrate resulted in an increase in activation by G-6-P and in an increase in malate inhibition of the enzyme. Furthermore, malate inhibition and G-6-P activation increased with increasing temperature. Activity measurements between 10° C and 45°C at a given concentration of the effectors revealed that the temperature optimum and maximum activities at that optimum varied with the effector applied. Under the influence of 5 mol m-3 L-malate the temperature optimum and maximum activity dropped drastically, especially when the substrate level was low (at 0.5 mol m-3 PEP from 32° C to 20° C). G-6-P raised the temperature optimum and maximum activity when the substrate level was low. If both malate and G-6-P were present, intermediate values were measured. We suggest that changes in metabolite levels in K. daigremontiana leaves can alter the temperature features of PEP-carboxylase so that the observed in vivo CO2 dark fixation can be explained on the basis of PEP-carboxylase activity.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 20 (1982), S. 71-80 
    ISSN: 0730-2312
    Keywords: aminoglycoside ; fluorescent paromomycin ; human fibroblasts ; lysosomes ; endocytosis ; exocytosis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Human fetal lung fibroblasts grown in the presence of dansyl-paromomycin (DNS-Pm), a fluorescent derivative of the aminoglycoside antibiotic, paromomycin, probably accumulate DNS-Pm in the lysosomes. The intracellular concentration of DNS-Pm is proportional to the extracellular concentration and to the length of time cells are exposed to the compound. The accumulation of DNS-Pm by human fibroblasts continued to increase for several days, reaching a saturation after 7 days. The kinetic data are consistent with the establishment of a steady state in the cell between fluid-phase pinocytosis and exocytosis of DNS-Pm. About 80% of the intracellular DNS-Pm was released in 24 hr when fresh medium without the analogue was added. The residual 20% remained within the cells, suggesting that it may be irreversibly bound to the lysosomes, endoplasmic reticulum, or ribosonius. The uptake of paromomycin by cells in culture may be a useful means to study error propagation during growth and lifespan of cells in vitro.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 210 (1984), S. 463-475 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Uteri from hibernating bats, Myotis lucifugus, collected periodically from Renfrew County, Ontario, were fixed in 2% glutaraldehyde and processed for electron microscopy or incubated in glyoxylic acid to show adrenergic nerves by fluorescence. The bat uterus is structurally typical of mammalian species; although the right uterine horn is permanently enlarged in parous bats due to hypertrophy of both myometrium and endometrium. Nerves were abundant between both longitudinal and circular layers of muscle cells. Unmyelinated, and some myelinated, axons, ranging from few to many, coursed generally parallel to the uterine long axis. Numerous axonal varicosities containing small dense-cored (adrenergic) vesicles or, less often, small agranular (cholinergic) vesicles, were found forming close nerve-muscle contacts between myometrial cells and blood vessels. Fluorescent microscopy showed a dense network of adrenergic nerves in parous uteri, but a sparse network in nulliparous uteri. A specific adrenergic nerve marker, 5-hydroxydopamine, greatly increased the density and in some instances, the size of granular vesicles, while 6-hydroxydopamine, which depletes adrenergic neutrotransmitter, reduced the number of dense-cored vesicles. Nulliparous uteri appeared unchanged by six daily injections of 0.1 μg estradiol-17β; 0.25 mg progesterone, or both; but parous uteri were greatly enlarged by all regimes. Nerve ultrastructure, however, appeared unaffected by steroid treatment; nor, despite the absolute dextral bias in implantation, were left-right differences observed. Gap junctions were not found between muscle cells in myometria of any bat uteri. Based on this study, we suggest that M. lucifugus may provide a most useful model for examination of neurogenic regulation of the uterus.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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