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1.
Summary From the roots ofEuphorbia cyparissias L. a highly irritant diterpene ester fraction was isolated and further resolved into its constituents. Together with some less active and some inactive isomers, the pure Euphorbia factors were characterized as new diesters of 13-hydroxyingenol and as triesters of the new 13,19-dihydroxyingenol. The Euphorbia factorsCy
6,Cy
11 andCy
14 are the strongest irritants of the ingenane ester type hitherto known,Cy
11 being at least as active as the standard diterpene ester type irritant 12-O-tetradecanoylphorbol-13-acetate (TPA).Acknowledgments. We are greatly indebted to the Wilhelm and Maria Meyenburg Foundation for financial support for the supply of plant material required for this investigation.The results were partially presented by H.H.O. at the 17. Hauptversammlung der Gesellschaft Deutscher Chemiker. München, 12.–16.9.1977. PhD-thesis. University of Heidelberg, 1978. 相似文献
2.
Summary Adult, male rats bred for over 10 generations on a soy meal-corn-diet had vitamin B12 values of liver and kidney about 10 times lower than the controls. If the deficient ration was supplemented with 5µg/kg of B12, these values were still about 1/5 of the controls. 3 weeks on the deficient diet lowered the B12 levels in the livers and kidneys of previously undepleted rats to about 1/2, and a similar diet containing 0.1% of iodized casein lowered these levels to about 1/3 of the normal values but did not lower the B12-concentration of organs of already deficient rats.Rats bred on the deficient diet and receiving for 1 month a supplement of 30µg/kg of vitamin B12 or the stock diet with a similar B12-content, had normal B12-levels in livers and kidneys. 相似文献
3.
We investigated the effect of aging on glucose uptake, glucose-induced O2 consumption, glucose-induced45Ca movements, and calmodulin content to elucidate age-related impairment of glucose-induced insulin release in pancreatic islets of Wistar rats. Intact pancreatic islets from old (24-month-old) rats showed impaired glucose-induced insulin release; glucose uptake and O2 consumption were lower in old than in young (2-month-old) or adult (12-month-old) rats. Moreover,45Ca uptake and calmodulin content were decreased in pancreatic islets from older rats, which explained the impairment in glucose-induced insulin release in aging. No major differences between the 3 age groups in glucose-induced45Ca efflux in pancreatic islets were observed. 相似文献
4.
R. Nesher W. F. Robinson L. Gibb S. P. Bishop F. A. Kruger 《Cellular and molecular life sciences : CMLS》1977,33(2):215-217
Summary Isolated rat hearts were subjected to hypoxic perfusion on a recirculating Langendorff apparatus. Following a 30-min-period of aerobic stabilization the hearts were perfused for 30 min with media equilibrated with 84% N2, 12% O2 and 4% CO2. At the end of the hypoxic period myocardial concentrations of cyclic AMP and cyclic GMP were determined by radioimmunoassay. Exposure to hypoxia resulted in a significant increase in cyclic AMP (p<0.01) and a decrease in cyclic GMP (p<0.05) as compared to hearts perfused for 60 min with media gassed with 96% O2, 4% CO2.Acknowledgment. We gratefully acknowledge the excellent technical assistance provided by Mrs Inger O. Boggs and Miss Patricia C. Hannigan. This work was supported in part by U. S. Public Health Service grant HL 14661 from the National Heart and Lung Institute, and by a grant from the Central Ohio Heart Chapter. 相似文献
5.
The effect of a phorbol ester upon the cholinergic regulation of potassium permeability in the rat submandibular gland 总被引:1,自引:0,他引:1
Acetylcholine releases calcium from cytoplasmic stores and permits an influx of calcium in salivary acinar cells. The resultant rise in [Ca2+]i causes an increase in potassium permeability which is an important part of the secretory response. We have investigated the effects of 12-0-tetradecanoyl phorbol-13-acetate, a potent activator of protein kinase C, upon this regulation of potassium permeability in superfused pieces of rat submandibular salivary gland. This compound inhibited the initial [Ca2+]o-independent component of the response of acetylcholine but had no effect upon the subsequent [Ca2+]o-dependent phase. This compound does not, therefore, appear to inhibit receptor-regulated calcium influx. 相似文献
6.
Vitamin B12 (VB12) is a putative modulator of the human circadian clock, improving entrainability to the 24 h light-dark cycle. The present study was intended to elucidate the mechanism of VB12 action in an animal model. In male rats free-running under constant dim illumination, a single light pulse of 50–1000 lux for 20 min given at circadian time (CT) 20 induced a 0.28 to 1.08 h phase advance and at CT 14 induced a 0.54 to 2.10 h phase delay. A 3 h intracerebroventricular (icv) infusion of 30 nmol VB12 starting 2 h prior to a 20 min 200 lux light pulse significantly amplified phase shifts in comparison with saline-treated or untreated controls. The mean phase advance (1.13 h) was 1.8-fold greater than that of saline-infused controls, whereas the mean phase delay (2.28 h) was 2.9-fold greater. These values were comparable to the maximal phase shifts caused by 1000 lux light pulses in untreated rats. Since the same VB12 treatment alone had failed to induce a phase shift in a previous experiment, these results indicate that VB12 strongly enhanced light pulse-induced phase shifts and thus augmented the entrainability of the circadian clock to light. 相似文献
7.
Summary A strain ofE. coli, when cultivated in avitamin-free medium, delivered from its synthesis small amounts of biotin, nicotinic acid, folic acid, vitamin B6, pantothenic acid and occasionally vitamin B12 into the cell-free filtrate, but not thiamine or inositol. Cultivated in avitamin-containing medium theE. coli strain absorbed certain amounts of biotin, nicotinic acid, vitamin B6, thiamine and vitamin B12, while inositol, folic acid and pantothenic acid were absorbed only in small amounts or not at all. 相似文献
8.
Cancer cell metabolism is characterized by limited oxidative phosphorylation in order to minimize oxidative stress. We have
previously shown that the flavonoid flavone in HT-29 colon cancer cells increases the uptake of pyruvate or lactate into mitochondria,
which is followed by an increase in O2−.. production that finally leads to apoptosis. Similarly, a supply of palmitoylcarnitine in combination with carnitine induces
apoptosis in HT-29 cells by increasing the mitochondrial respiration rate. Here we show that flavone-induced apoptosis is
increased more than twofold in the presence of palmitoylcarnitine due to increased mitochondrial fatty acid transport and
the subsequent metabolic generation of O2−. in mitochondria is the initiating factor for the execution of apoptosis.
Received 12 August 2005; received after revision 12 October 2005; accepted 14 October 2005 相似文献
9.
Véronique Pons Nizar Serhan Stéphanie Gayral Camille Malaval Michel Nauze Nicole Malet Muriel Laffargue Céline Galés Laurent O. Martinez 《Cellular and molecular life sciences : CMLS》2014,71(9):1775-1788
The protective effect of high density lipoproteins (HDL) against atherosclerosis is mainly attributed to their capacity to transport excess cholesterol from peripheral tissues back to the liver for further elimination into the bile, a process called reverse cholesterol transport (RCT). Recently, the importance of the P2Y13 receptor (P2Y13-R) was highlighted in HDL metabolism since HDL uptake by the liver was decreased in P2Y13-R deficient mice, which translated into impaired RCT. Here, we investigated for the first time the molecular mechanisms regulating cell surface expression of P2Y13-R. When transiently expressed, P2Y13-R was mainly detected in the endoplasmic reticulum (ER) and strongly subjected to proteasome degradation while its homologous P2Y12 receptor (P2Y12-R) was efficiently targeted to the plasma membrane. We observed an inverse correlation between cell surface expression and ubiquitination level of P2Y13-R in the ER, suggesting a close link between ubiquitination of P2Y13-R and its efficient targeting to the plasma membrane. The C-terminus tail exchange between P2Y13-R and P2Y12-R strongly restored plasma membrane expression of P2Y13-R, suggesting the involvement of the intra-cytoplasmic tail of P2Y13-R in expression defect. Accordingly, proteasomal inhibition increased plasma membrane expression of functionally active P2Y13-R in hepatocytes, and consequently stimulated P2Y13-R-mediated HDL endocytosis. Importantly, proteasomal inhibition strongly potentiated HDL hepatic uptake (>200 %) in wild-type but not in P2Y13-R-deficient mice, thus reinforcing the role of P2Y13-R expression in regulating HDL metabolism. Therefore, specific inhibition of the ubiquitin–proteasome system might be a novel powerful HDL therapy to enhance P2Y13-R expression and consequently promote the overall RCT. 相似文献
10.
D. Ryan D. Koss E. Porcu H. Woodcock L. Robinson B. Platt G. Riedel 《Cellular and molecular life sciences : CMLS》2013,70(14):2603-2619
We recently generated an advanced mouse model of Alzheimer’s disease (AD) by targeted knock-in of single-copy mutated human amyloid precursor-protein (APP) and tau genes, crossed with a non-symptomatic presenilin (PS1A246E) over-expressing mouse line. These PLB1Triple mice presented with age-dependent and AD-relevant phenotypes. Homozygous PLB1Triple mice aged 4–12 months were assessed here in a battery of spatial learning tasks: Exp.1 radial-arm water maze (spatial reference and working memory) Exp.2 open-field water maze (spatial reference memory); Exp.3 home cage observation system with spatial learning (IntelliCage); Exp.4 spontaneous object recognition (SOR; novel object and spatial object shift). A separate test with high-expression transgenic APP mice matching the design of experiment 1 was also performed. Spatial deficits in PLB1Triple mice were confirmed at 12, but not 4 months in both water maze tasks. PSAPP mice, by contrast, presented with severe yet non-progressive spatial learning deficits already at 4 months. During tests of spatial learning in SOR and IntelliCage, PLB1Triple mice neither acquired the location of the water-rewarded corner, nor recognize novel or spatially shifted objects at 4 months, indicating these protocols to be more sensitive than the water maze. Collectively and in line with AD symptomatology, PLB1Triple mice present with a graded and progressive age-dependent loss of spatial memory that can be revealed by the use of a battery of tasks. With the emergence of subtle deficits progressively increasing in severity, PLB1Triple mice may offer a more patho-physiologically relevant model of dementia than aggressive expression models. 相似文献
11.
Summary 1-O-Monoalkylglycerols with C12 to C20 chains were identified in the scent, gland secretions of the western diamondback rattlesnake (Crotalus atrox). This is the first documentation of these compounds in the skin secretions of a reptile. 相似文献
12.
U. Pontén 《Cellular and molecular life sciences : CMLS》1964,20(5):287-289
Zusammenfassung 73 Ratten wurden hyperventiliert und mit Gasgemischen verschiedener CO2-Gehalte (0–12%) während 30–180 min beatmet (arteriellerP
CO
2 12–107 Torr). Die Versuchstiere wurdenin situ eingefroren und der CO2-Gehalt des Gehirngewebes mit eigener Methode bestimmt. Dissoziationskurve und Pufferkapazität des Gehirngewebes für CO2
in vivo werden mitgeteilt. 相似文献
13.
Zusammenfassung Die Verteilung von radioaktivem Vitamin B12 und 4-Jodphenylalanin in tumortragenden Mäusen wurde ganztierautoradiographisch untersucht. Die grösste Aufnahme von B12 wurde im weichen fibroblastischen Osteosarkom gefunden, während 4-Jodphenylalanin in einem Ehrlich-Ascites-Tumor aufgenommen wurde. 相似文献
14.
K. C. Saxena S. Ghatak S. C. Agarwala 《Cellular and molecular life sciences : CMLS》1954,10(12):488-489
Zusammenfassung Zusatz von Vitamin B12 in Kulturnährböden hemmt die Thiamin-Biosynthese von frisch isoliertenE.-coli-Stämmen. Diese Hemmung steht im Verhältnis zur zugesetzten Menge von Vitamin B12. 相似文献
15.
T. W. Baumann 《Cellular and molecular life sciences : CMLS》1972,28(10):860-862
Summary In meristematic root tip cells ofScilla sibirica (2n=12 and 3n=18) the following results were obtained with the aid of autoradiography: 1. The average duration of the mitotic cycle (2n=12) is 69.5 h. The G1-phase lasts 36.5 h, the DNA synthetic phase 17.5 h, the G2-phase 8 h and mitosis 7.5 h. 2. There are no marked differences in the lengths of the cell cycles nor in the duration of the various phases between diploid and triploid plants. 相似文献
16.
Muñoz U Bartolomé F Esteras N Bermejo-Pareja F Martín-Requero A 《Cellular and molecular life sciences : CMLS》2008,65(21):3507-3519
It has been proposed that neuroinflammation, among other factors, may trigger an aberrant neuronal cell cycle re-entry leading
to neuronal death. Cell cycle disturbances are also detectable in peripheral cells from Alzheimer’s disease (AD) patients.
We previously reported that the anti-inflammatory 15- deoxy-Δ12,14-prostaglandin J
2 (15d-PGJ
2) increased the cellular content of the cyclin-dependent kinase inhibitor p27, in lymphoblasts from AD patients. This work
aimed at elucidating the mechanisms of 15d-PGJ
2-induced p27 accumulation. Phosphorylation, half-life, and the nucleo-cytoplasmic traffic of p27 protein were altered by 15d-PGJ2
by mechanisms dependent on PI3K/Akt activity. 15d-PGJ
2 prevents the calmodulin-dependent Akt overactivation in AD lymphoblasts by blocking its binding to the 85-kDa regulatory
subunit of PI3K. These effects of 15d-PGJ
2 were not mimicked by 9,10-dihydro-15-deoxy-Δ12,14- prostaglandin J
2, suggesting that 15d-PGJ
2 acts independently of peroxisome proliferator-activated receptor γ activation and that the α,β-unsaturated carbonyl group
in the cyclopentenone ring of 15d-PGJ
2 is a requisite for the observed effects.
Received 14 July 2008; received after revision 2 September 2008; accepted 12 September 2008 相似文献
17.
C. M. Caldarera B. Barbiroli M. Marchetti 《Cellular and molecular life sciences : CMLS》1966,22(7):456-456
Riassunto La somministrazione dietetica di vitamina B12 e di acido orotico determina un aumento della incorporazione dellal-serina C14 nello RNA solubile del fegato di pulcino carente di B12, mentre non è in grado di influenzare quella dellal-leucina14C e dellal-metionina14C. 相似文献
18.
Yoshida Y Ohkuri T Kino S Ueda T Imoto T 《Cellular and molecular life sciences : CMLS》2005,62(9):1047-1055
We investigated the activity and the internal motions of a stabilized mutant hen lysozyme (HEL) in which the residues M12 and L56 were mutated to L and F, respectively (LF mutant HEL). The result of the activity measurements against glycol chitin at various temperatures suggested that the temperature dependence of the activity of LF mutant HEL shifted to the high-temperature side compared with that of wild-type HEL. The detailed internal motions of LF mutant HEL in the absence and presence of a substrate analogue, (NAG)3, were examined by model-free analysis at 35°C. The results showed that the internal motions of LF mutant HEL in the presence of (NAG)3 were drastically restricted compared with those in wild-type HEL. Our findings thus suggested that the mutation to the stabilized lysozyme restricted internal motions required for the enzymatic reaction.Received 8 February 2005; accepted 10 March 2005Y. Yoshida and T. Ohkuri contributed equally to this work. 相似文献
19.
Thelma Isaacs 《Cellular and molecular life sciences : CMLS》1969,25(3):239-240
Zusammenfassung Ca3Y2Ge3O12 wurde in chemisch homogener Form auf hydrothermalem Weg hergestellt. Es besitzt eine Garnet-Struktur mit dem Gitterparametera
0=12,804 Å. 相似文献
20.
Martínez Muñoz C Post JA Verkleij AJ Verrips CT Boonstra J 《Cellular and molecular life sciences : CMLS》2001,58(7):990-996
Activation of mitogen-activated protein (MAP) kinase is essential for cyclin D1 expression and provides a link between mitogenic
signalling and cell cycle progression. Hydrogen peroxide (H2 O2 ) activates MAP kinase; however, it is not known whether this leads to cyclin D expression. Sustained expression of cyclin
D1 and D2 was observed when Her14 fibroblasts were incu-bated with 3 mM or higher H2 O2 concentrations. Similar results were obtained when cells were incubated in the presence of serum (FCS). However, the sustained
expres-complex sion of cyclin D1 and D2 upon H2 O2 treatment was not due to the MAP kinase pathway, because MAP kinase kinase inhibitors did not inhibit cyclin D expression.
Furthermore, cyclin D1 and D2 levels remained constant even after addition of a protein synthesis inhibitor, indicating that
the effect of H2 O2 was not due to induction of protein synthesis. These results indicate that H2 O2 reversibly inhibits the ubiquitin-proteasome dependent degra-dation of cyclin D1 and D2, probably by transiently in-hibiting
ubiquitination and/or the proteasome.
Received 12 March 2001; received after revision 5 April 2001; accepted 9 April 2001 相似文献