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Uridine phosphorylase from Hymenolepis diminuta [Cestoda]: Kinetics and ihibition by pyrimidine nucleoside analogs

100%

Drabikowska A. K.

Acta Biochimica Polonica

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1996

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tom 43

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nr 4

A single pyrimidine nucleoside phosphorylase was found in the cytoplasmic extract from Hymenolepis diminuta. This enzyme preferentially cleaves uridine and, to a much lesser extent, thymidine. Its presence directly indicates the existence of pyrimidine nucleoside salvage pathway in this parasite. Detailed kinetic studies in the phosphorolytic and synthetic direction pointed to the sequential mechanism of these reactions. For phosphorolysis, Kurd = 33 ^M and Kp = 806 nM. For synthesis of uridine, KUra = 204 jiM and Ki.p.rib.= 50 pM. Over six times higher Km for uracil than for uridine indicates that phosphorolysis is the favoured reaction in this tapeworm. Well known inhibitors of mammalian uridine phosphorylase: 2,2'-anhydro-5- -ethyluridine and l-(l,3-dihydroxy-2-propoxymethyl)-5-benzyluracil (DHPBU), both with Ki = 0.07 nM were potent competitive inhibitors of the enzyme from H. diminuta. The newly synthesized 2,3'-anhydro-5-ethyluridine (K. Felczak,unpublished) showed only moderate inhibitory activity (Ki = 14 jiM) similarly as l-(l,3-dihydroxy-2- -propoxy-methyl)-5-benzyluracil. The same order of Ki values obtained for the investigated inhibitors vs uridine phosphorylase, irrespective whether the enzyme was isolated from rat intestinal mucosa (Drabikowska etal., 1987,Biochem. Pharmacol. 36,4125-4128) or H. diminuta may point to a great similarity between binding sites on the parasite and the host enzyme.

2

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Breakdown of [3H]-thymidine and the inability to measure the proliferation of lymphocytes in whole blood cultures

100%

Stec J., Reichert M., Rachubik J.

Bulletin of the Veterinary Institute in Puławy

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1999

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tom 43

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nr 1

Several components of sheep blood extensively catabolize nucleosides, including thymidine. Part of the radioactivity from tritiated thymidine, in whole blood cultures, is quickly rendered unincorporable as the compound is metabolized to thymine and further breakdown products. Thus, cells continue to proliferate without incorporating radioactivity from the medium. Furthemore, variability in the degree of catabolism varied from animal to animal, so that neither measurement of the depletion of radioactivity from the medium nor measurement of the amount of label incorporated into cultures can be used as a quantitative index of the cell proliferation or immunocompetence.

3

In vivo phosphorylation of alloxymethyl purine and pyrymidine acyclonucleosides and the inhibitory effect of these compounds on thymidine and deoxyguanosine kinases

100%

Modrzejewska H., Greger J., Lewandowska U., Fidek W.

Acta Biochimica Polonica

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1994

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tom 41

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nr 2

4

The effects of antagonists of receptors for gastrin, cholecystokinin and bombesin on growth of gastroduodenal mucosa and pancreas

84%

Dembinski A., Warzecha Z., Konturek S. J., Zhi Cai R., Schally A. V.

Journal of Physiology and Pharmacology

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1991

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tom 42

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nr 2

The effects of gastrin, cholecystojdnin (CCK) and bombesin on the DNA synthesis, as a biochemical indicator of trophic action in the gastroduodenal mucosa and the pancreas have been examined in rats fasted for 48 h and in rats refed for 16 h with or without administration of specific receptor antagonists for bombesin, gastrin and CCK. Bombesin and gastrin administered three times daily for 48 h in fasted rats significantly increased the rate of DNA synthesis as measured by the incorporation of [³H] thymidine into DNA in each tissue tested. CCK significantly increased DNA synthesis in the duodenal mucosa and pancreatic tissue, but not in the gastric mucosa. The stimulation of DNA synthesis induced by bombesin in the gastroduodenal mucosa and pancreas was abolished by bombesin/GRP receptor antagonist, RC-3095. RC-3095 did not affect DNA synthesis stimulated by gastrin and CCK in these tissues. L-365,260, a receptor antagonist for gastrin suppressed the DNA synthesis induced by gastrin but not by CCK or bombesin in the gastrointestinal mucosa and pancreas. L-364, 718 a specific antagonist for CCK receptors was effective only against CCK stimulated duodenal mucosa and pancreatic growth. Refeeding of 48 h fasting rats strongly enhanced the DNA synthesis in all tissues tested, and this effect was significantly reduced in the gastroduodenal mucosa by blocking only gastrin receptors (with L-365, 260) and that in the duodenal mucosa and the pancreas by antagonizing of CCK receptors (with L-364, 718). Antagonism of bombesin receptors (with RC-3095) did not significantly affect the stimulation of DNA synthesis induced by refeeding in all tissues tested. This study indicates that the stimulation of DNA synthesis can be achieved by exogenous gastrin, CCK and bombesin acting through separate receptor but that only gastrin and CCK play the major role in the postprandial stimulation of the growth of gastroduodenal mucosa and pancreatic tissue.

5

The influence of liposomes containing cholesterol on phagocytic activity and proliferation of Tetrahymena cells

84%

Fabczak H.

Acta Protozoologica

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1988

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tom 27

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nr 2

6

Regional differences in the vulnerability of substantia nigra dopaminergic neurons in weaver mice

84%

Marti J., Santa-Cruz M. C., Molina V., Serra R., Bayer S. A., Ghetti B., Hervas J. P.

Acta Neurobiologiae Experimentalis

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2009

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tom 69

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nr 2

198-206

Vulnerability of midbrain dopaminergic (DA) neurons in the weaver mouse was studied at postnatal (P) days 8 and 90, in chosen coronal levels throughout the anteroposterior (AP) extent of the substantia nigra pars compacta (SNc). Wild-type (+/+) and homozygous weaver (wv/wv) mice used were the offspring of pregnant dams injected in several cases with tritiated thymidine on embryonic days 11-15. DA neurons were identified for their tyrosine hydroxylase immunoreactivity. Data reveal that at P8, the frequency of both +/+ and wv/wv late-generated DA cells increases from rostral to caudal SNc. No apparent DA-cell loss was observed at P8 in the mutant genotype, irrespective of the AP level considered. However, throughout the AP, there was a significant reduction in the number of these neurons at any level in 90-day-old weavers. Comparison of P8 and P90 +/+ SNc suggests that cell death is not a major aspect in the developmental regulation of normal DA neurons, although numerical cell depletion in the postnatal development of weaver SNc probably results from the amplification of a basal cell-death process, which affected all the coronal levels studied.

7

Usefulness of neutral red uptake method for investigation of the bovine leukocyte viability and lymphocyte proliferation

84%

Fijalkowski K., Nawrotek P., Czernomysy-Furowicz D.

Advances in Agricultural Sciences

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2011

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tom 14

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nr 1-2

8

Inhibitory effects of herbal decoction Ojeoksan on proliferation and migration in vascular smooth muscle cells

84%

Han B. H., Yoon J. J., Kim H. Y., Ahn Y. M., Jin S. N., Wen J. F., Lee H. S., Lee Y. J., Kang D. G.

Journal of Physiology and Pharmacology

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2019

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tom 70

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nr 2

9

Structure and dynamics of a DNA duplex containing single alpha-anomeric deoxyadenosine residue

84%

Bielecki L., Adamiak R. W.

Acta Biochimica Polonica

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2001

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tom 48

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nr 1

Structure and dynamics of an undecamer DNA duplex containing a single a-anomeric deoxyadenosine residue placed in opposition to a thymidine unit have been studied using simulation of molecular dynamics in aqueous solution. Despite several noticeable deviations from the B-DNA duplex structure caused by the anomerisation, such as: West type puckering of the a-anomeric sugar, disrupted base stacking pattern and unstable duplex bending, the formation of a non-classical a-dA-T pair was observed. A novel way of visual presentation of trajectory data allowing high throughput screening of the conformational parameters is presented.

10

Met-enkephalin modulates dexamethasone-induced leucocyte suppression in sheep

67%

Pierzchala-Koziec K., Zubel J., Kepys B.

Acta Biologica Cracoviensia. Series Zoologia

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2001

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tom 43

Ograniczanie wyników

Uridine phosphorylase from Hymenolepis diminuta [Cestoda]: Kinetics and ihibition by pyrimidine nucleoside analogs

Breakdown of [3H]-thymidine and the inability to measure the proliferation of lymphocytes in whole blood cultures

In vivo phosphorylation of alloxymethyl purine and pyrymidine acyclonucleosides and the inhibitory effect of these compounds on thymidine and deoxyguanosine kinases

The effects of antagonists of receptors for gastrin, cholecystokinin and bombesin on growth of gastroduodenal mucosa and pancreas

The influence of liposomes containing cholesterol on phagocytic activity and proliferation of Tetrahymena cells

Regional differences in the vulnerability of substantia nigra dopaminergic neurons in weaver mice

Usefulness of neutral red uptake method for investigation of the bovine leukocyte viability and lymphocyte proliferation

Inhibitory effects of herbal decoction Ojeoksan on proliferation and migration in vascular smooth muscle cells

Structure and dynamics of a DNA duplex containing single alpha-anomeric deoxyadenosine residue

Met-enkephalin modulates dexamethasone-induced leucocyte suppression in sheep