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71.
Studies on some specific Ap4A-degrading enzymes with the use of various methylene analogues of P1P4-bis-(5'',5''''''-adenosyl) tetraphosphate. 总被引:1,自引:0,他引:1
Six new methylenephosphonate analogues of P1P4-bis-(5',5'-adenosyl) tetraphosphate, Ap4A, having P2-P3 carbon bridges CF2, CCl2 and CH2CH2 or P1-P2 and P3-P4 carbon bridges CF2, CCl2 and CH2CH2 in the tetraphosphate chain, were examined as substrates or inhibitors for two specific Ap4A-degrading enzymes: (asymmetrical) Ap4A hydrolase (EC 3.6.1.17) from yellow-lupin seeds and (symmetrical) Ap4A hydrolase (EC 3.6.1.41) from Escherichia coli. All analogues in which the central oxygen atom was replaced by a stable carbon bridge were hydrolysed by the asymmetrical hydrolase (CF2 greater than CCl2 greater than O greater than CHBr greater than CH2 greater than CH2CH2). As expected, these analogues were not hydrolysed by the symmetrical hydrolase, which was also unable to act on analogues having P1-P2 and P3-P4 carbon bridges. 相似文献
72.
K Krzemiński W Niewiadomski K Nazar 《European journal of applied physiology and occupational physiology》1989,59(5):377-384
Eighteen male volunteers (aged 20-23 years), not involved in any sporting activities, were submitted to 13 weeks of training consisting of 30 min exercise [at 50%-75% maximal oxygen intake (VO2max)] on a cycle ergometer, performed 3 times a week. Every 4 weeks cardiac function was evaluated by measuring the systolic time intervals at rest and during submaximal cycle exercise. Stroke volume (SV), heart rate (HR) and blood pressure (BP) responses to submaximal exercise, VO2max and anaerobic threshold (AT) were also determined. Significant increases in VO2max, increases in AT and SV at the submaximal exercise intensities, as well as decreases in HR and BP were found after 4 weeks of training. Resting systolic time intervals were not affected by training, but during the submaximal cycle exercise the values of the pre-ejection period (PEP) and isovolumic contraction time (ICT) corresponding to HR of 100 beats.min-1 were significantly lowered after 13 weeks of training, whereas PEP, ICT and total electromechanical systole corresponding to HR of 130 beats.min-1 were significantly shortened by the 4th week. The ratios of PEP:LVET (left ventricular ejection time) and ICT:LVET during submaximal exercise were significantly lowered by training starting from the 8th week. These changes might be interpreted as evidence of the training-induced enhancement of the "contractility reserve", i.e. the ability to increase heart muscle contractility with increasing exercise intensity. 相似文献
73.
J Stachura M Pietroń K Nowak Z Rudzki W Nowak 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1989,27(4):227-231
DAKO quick staining kits were used to immunostainings for Epithelial Membrane Antigen (EMA) Neuron Specific Enolase (NSE) and S-100 protein (S-100) in 18 carcinoid tumors of the gastrointestinal tract classified according to Soga and Tazawa. EMA was always absent in carcinoid tumors, being at the same time present within glandular epithelium. 88% of cases showed positive immunostaining for NSE. S-100 immunostaining showed immunopositive stellate cells present within the tumor especially within type A carcinoids. In addition in one carcinoid tumor thick, strongly S-100 positive bundles were noticed at the periphery of nests of tumor cells. Combined immunohistochemical and ultrastructural studies are needed to elucidate interrelation of neoplastic and neural elements within carcinoid tumorsa. 相似文献
74.
J Szczudrawa K Urbańczyk A Urban J Stachura 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1989,27(2):73-81
The aim of the study was to evaluate the incidence of the reactions for vimentin and desmin in gastric leiomyomas routinely processed in formalin and embedded i paraffin. The material studied included four benign leiomyomas, seven malignant leiomyomas and three malignant epithelioid leiomyomas. A positive reaction to vimentin was found in 13 out 14 leiomyomas under study. The number of neoplastic cells showing vimentin expression was larger in malignant, especially epithelioid leiomyomas than in non-malignant leiomyomas. A positive reaction for desmin in neoplastic cells was found in 9 leiomyomas 64%. One non-malignant leiomyoma showed a moderate reaction. In the remaining eight cases the reaction was weak and occurred in single neoplastic cells. Coexpression of vimentin and desmin in neoplastic cells occurred in 8 out of 9 leiomyomas with a positive reaction for desmin. Coexpression of vimentin and desmin occurred also in the smooth muscle cells of blood vessels in all 14 cases. A weak reaction for desmin or its lack in the tumour cells of leiomyomas with its marked expression in the smooth muscle cells of the blood vessels and gastric wall outside the tumor points rather to a small number of desmin filaments in the neoplastic cells than to their destruction by fixation in formalin. The occurrence of the reaction to desmin only in a limited number of neoplastic cells questions the reliability of its use in the oligopiopsy material. 相似文献
75.
Expression of nonspecific cross-reacting antigen species in myeloid leukemic patients and healthy subjects 总被引:1,自引:0,他引:1
The reactivity of two monoclonal antibodies recognizing NCA-95 and NCA-55 (MAb 47 and MAb 192, respectively) with a polyclonal anti-NCA serum in myeloid leukemic cells isolated by density gradient centrifugation was compared using an immunofluorescence test (IF). It was observed that the blood myeloid cells in 78.8% of the patients with different types of myelocytic leukemias and all granulocytes of 15 normal donors showed similar expression of the NCA species studied. The leukocytes of the remaining patients did not synthesize the NCA-95 species regardless of the maturation stage of the cells studied. In two patients, synthesis of this NCA form was limited to the fractions containing myelocytes and metamyelocytes. We have found that all anti-NCA antibodies studied recognized different antigenic epitopes in a myeloid cell series. A relationship between the patient's survival and the proportion of NCA-containing cells was also observed. 相似文献
76.
Szczepan M. Biliński 《Chromosoma》1989,97(4):321-326
In the oocytes of Eomenacanthus stramineus accessory nuclei arise by budding from the nuclear envelope. It is suggested that microtubules and the thick layer of the nuclear lamina are involved in this process. Newly formed accessory nuclei contain aggregations of fibrillogranular material. These aggregations are slightly Feulgen positive, RNA negative and stain positively with the AgNOR method. During later developmental stages one dense, RNA-positive inclusion appears in each accessory nucleus. These inclusions consist of on Ag-NOR-positive cortical layer and an Ag-NOR-negative core. The function of accessory nuclei in the species investigated is discussed in the light of these results. 相似文献
77.
Pertussis toxin inhibits CAMP-induced desensitization of adenylate cyclase in Dictyostelium discoideum 总被引:2,自引:0,他引:2
B. Ewa Snaar-Jagalska Peter J. M. Van Haastert 《Molecular and cellular biochemistry》1990,92(2):177-189
cAMP binds to surface receptors of Dictyostelium discoideum cells, transducing the signal to adenylate cyclase, guanylate cyclase and to chemotaxis. The activation of adenylate cyclase is maximal after 1 min and then declines to basal levels due to desensitization, which is composed of two components: a rapidly reversible adaptation process, and a slowly reversible down-regulation of cAMP receptors. Adaptation is correlated with receptor phosphorylation.The chemotactic response and the cAMP-induced cGMP response were not significantly altered in D. discoideum cells pretreated with pertussis toxin. The initial increase of cAMP levels was identical in control and toxin treated cells, suggesting that activation of adenylate cyclase was also not affected. However, cAMP synthesis continued in toxin treated cells, due to a strongly diminished desensitization. Pertussis toxin inhibited the adaptation of adenylate cyclase stimulation, but not the down-regulation or phosphorylation of the cAMP receptors. Adenylate cyclase in D. discoideum membranes can be stimulated or inhibited by GTP, depending on the conditions used. Pertussis toxin did not affect the stimulation of adenylate cyclase but nullified the inhibition. In membranes from desensitized control cells, stimulation of adenylate cyclase by GTP was lost, whereas inhibition was retained. Stimulation of adenylate cyclase in membranes from desensitized pertussis toxin treated cells was diminished but not absent. These results indicate that receptor phosphorylation is not sufficient for adaptation of adenylate cyclase, and that a pertussis toxin substrate, possibly Gi, is also involved in this process.Abbreviations used ATPS
Adenosine 5-0-(3-Thiotriphosphate)
- GTPS
Guanosine 5-0-(3-thiotri-phosphate)
- (Sp)-cAMPS
Adenosine 3,5-monophosphorothioate-Sp-isomer
- dcAMP
2-deoxyadenosine 3,5-monophosphate
- Hepes
N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid
- DTT
Dithiothreitol
- buffer A
10 mM KH2PO4/Na2HPO4, pH 6.5
- buffer B
40 mM Hepes/NaOH, 0.5 mM EDTA, 250 mM sucrose, pH 7.7 相似文献
78.
79.
Morphological and seed protein analyses of 26 species of the generaLolium, Festuca andVulpia confirmed their close systematic affinities. Six inflorescence characters readily differentiatedFestuca fromLolium. Protein similarities betweenFestuca of sect.Bovinae and cross-pollinated species ofLolium, coupled with cytogenetic and crossability data, substantiate that they should be united into one genus.Vulpia had phenetic similarities with sect.Scariosae, Montanae andOvinae ofFestuca. Lolium, Festuca, andVulpia are most likely derived from a common ancestral form which was close toFestuca pratensis andLolium perenne. 相似文献
80.
A B Slebodziński 《Acta physiologica Polonica》1988,39(5-6):364-379
Danowski et al. (1951) were probably the first who showed an increase of PBI in infants shortly after birth. Later a number of investigators presented further evidence on the increased thyroid gland function in newborns. This condition named "neonatal thyroid hyperactivity" [Fisher and Oddie, 1964] was described also in animals. The available data indicate that all the newborn mammals till now studied, independently of the maturation stage of development they reach at birth, display some features of thyroid hyperactivity, but in some it does not lead to hyperiodothyroninaemia. Interspecies differences coincide well with significance of the thyroid hormones for neonatal thermogenesis. There are few sequential studies of the three principal iodothyronines: T4, T3 and rT3 available at present. The most comprehensive data concern infants, newborn lambs and pigs. Immediately after birth, there is a sudden rise in serum thyroid hormone concentrations, with some species differences related to the degree of the increase and to the iodothyronines involved. The course of the postnatal hyperiodothyroninaemia is dependent on the maturation level reached at birth, food intake, and cooling relative to extrauterine environment. At least five main factors contribute to the immediate postnatal hyperiodothyroninaemia: 1) abrupt depletion of the preformed fetal hormonal iodine stores; 2) preferential T3 secretion; 3) increase in the T4 to T3 monodeiodination in the peripheral tissues; 4) a release of thyroid hormone content from peripheral reservoirs to plasma, and 5) action of other hormone(s) concomitantly released at birth. From the point of view of the thermal adaptability, the newborn mammals fall into two distinct groups: first, in which immediately after birth the metabolic rate decreases, and second, in which the metabolic rate increases, after cooling. Our understanding of the role and significance of hormonal factors involved in mechanisms of the postnatal thermogenesis is incomplete. However, some similarities in adaptation to cold in adults and in newborns seem to be relevant. Cold adaptation is accomplished by development of nonshivering thermogenesis (NST) depending on NA. The presence of brown adipose tissue (BAT) is essential for NA thermogenic action. According to the common opinion, based on data from laboratory animals and human baby, non-shivering thermogenesis, but not shivering, predominates in newborns. However, data from domestic animals indicate that shivering thermogenesis may be of comparable or greater thermogenic capacity than NST at birth. Besides, there are some newborns which have little or no BAT and associated NST.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献