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1.
In vivo EMG biofeedback was found to be an effective pedagogical tool for removing unwanted left-hand tension in nine violin and viola players. Improvement occurred rapidly and persisted throughout a 5-month follow-up period. Further studies will be necessary to assess the effect of biofeedback independent of placebo effects. The brevity of the method and the magnitude of improvement warrant further investigation. 相似文献
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3.
Judith T. Irvine 《American anthropologist》1998,100(2):580-581
The Oral History and Literature of the Wolof People of Waalo, Northern Senegal. Samba Diop. Lewiston, Canada; Edwin Mellen Press, 1995. 389 pp. 相似文献
4.
Human umbilical vein endothelial cells were grown to confluence, as first passage cells, on coverslips. Treatment with ionomycin or histamine caused a sustained rise in intracellular Ca2+ (measured by Fura-2 fluorescence), but after treatment with thrombin, only a transient rise in Ca2+ was observed. Furthermore, the addition of thrombin after ionomycin or histamine lowered the raised Ca2+ back to near control levels. This effect of thrombin was concentration dependent, with increasing concentrations producing increases in both the rate and extent of the lowering of Ca2+. A similar effect of thrombin was seen on video imaging of Fura-2-loaded cell monolayers. The Ca2(+)-lowering effect of thrombin was not mimicked by phorbol 12-myristate 13-acetate nor blocked by staurosporine, indicating a lack of involvement of protein kinase C; intracellular pH also does not appear to be involved. The mechanism by which thrombin lowers cytoplasmic Ca2+ is due mainly to inhibition of Ca2+ entry since thrombin prevented the stimulated influx of Mn2+ caused by histamine or ionomycin. It may therefore be that in vivo under certain physiological or pathological conditions, thrombin's effects on intracellular Ca2+ are more transient than those of histamine, and thrombin also may induce transience in histamine's actions. 相似文献
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Metabolism of D-myo-inositol 1,3,4,5-tetrakisphosphate by rat liver, including the synthesis of a novel isomer of myo-inositol tetrakisphosphate. 总被引:10,自引:9,他引:1 下载免费PDF全文
S B Shears J B Parry E K Tang R F Irvine R H Michell C J Kirk 《The Biochemical journal》1987,246(1):139-147
1. We have studied the metabolism of Ins(1,3,4,5)P4 (inositol 1,3,4,5-tetrakisphosphate) by rat liver homogenates incubated in a medium resembling intracellular ionic strength and pH. 2. Ins(1,3,4,5)P4 was dephosphorylated to a single inositol trisphosphate product, Ins(1,3,4)P3 (inositol 1,3,4-trisphosphate), the identity of which was confirmed by periodate degradation, followed by reduction and dephosphorylation to yield altritol. 3. The major InsP2 (inositol bisphosphate) product was inositol 3,4-bisphosphate [Shears, Storey, Morris, Cubitt, Parry, Michell & Kirk (1987) Biochem. J. 242, 393-402]. Small quantities of a second InsP2 product was also detected in some experiments, but its isomeric configuration was not identified. 4. The Ins(1,3,4,5)P4 5-phosphatase activity was primarily associated with plasma membranes. 5. ATP (5 mM) decreased the membrane-associated Ins(1,4,5)P3 5-phosphatase and Ins(1,3,4,5)P4 5-phosphatase activities by 40-50%. This inhibition was imitated by AMP, adenosine 5'-[beta gamma-imido]triphosphate, adenosine 5'-[gamma-thio]triphosphate or PPi, but not by adenosine or Pi. A decrease in [ATP] from 7 to 3 mM halved the inhibition of Ins(1,3,4,5)P4 5-phosphatase activity, but the extent of inhibition was not further decreased unless [ATP] less than 0.1 mM. 6. Ins(1,3,4,5)P4 5-phosphatase was insensitive to 50 mM-Li+, but was inhibited by 5 mM-2,3-bisphosphoglycerate. 7. The Ins(1,3,4,5)P4 5-phosphatase activity was unchanged by cyclic AMP, GTP, guanosine 5'-[beta gamma-imido]triphosphate or guanosine 5'-[gamma-thio]triphosphate, or by increasing [Ca2+] from 0.1 to 1 microM. 8. Ins(1,3,4)P3 was phosphorylated in an ATP-dependent manner to an isomer of InsP4 that was partially separable on h.p.l.c. from Ins(1,3,4,5)P4. The novel InsP4 appears to be Ins(1,3,4,6)P4. Its metabolic fate and function are not known. 相似文献
8.
Selenocysteine's mechanism of incorporation and evolution revealed in cDNAs of three glutathione peroxidases 总被引:5,自引:0,他引:5
G T Mullenbach A Tabrizi B D Irvine G I Bell J A Tainer R A Hallewell 《Protein engineering》1988,2(3):239-246
The nonsense codon, UGA, has for the first time recently been shown to encode selenocysteine in two proteins, mouse glutathione peroxidase (GSH-Px) (EC 1.11.1.9) and bacterial formate dehydrogenase. A co-translational rather than post-translational selenium-incorporation mechanism has been implicated. Furthermore, high expression levels of GSH-Px have suggested that suppression of termination is efficient and specific. We have isolated and characterized pituitary, kidney and placenta cDNAs for bovine, human and mouse GSH-Px respectively. It is demonstrated that this novel suppression event occurs in diverse tissues, in at least three mammalian species and at the translational step. Surprisingly, GSH-Px is shown to be extramitochondrially encoded, indicating a cytosolic suppression event rather than one utilizing the mitochondria's well-documented extended codon-reading ability. Sequence analysis reveals that a simple proximal contextual pattern responsible for readthrough does not exist. Analysis of predicted secondary structures of mRNAs, however, has revealed a conformation which may be unique to selenocysteine proteins and may prove useful as a tool for artificial incorporation of selenocysteines. A human intron for GSH-Px from an unspliced mRNA has been isolated whose position indicates an ancient, divergent evolutionary relationship with thioredoxin-S2, rather than an independent convergent one. 相似文献
9.
Jeanine Brederoo Piet de Wildt Corrie Popp-Snijders Robin F. Irvine Alan Musgrave Herman van den Ende 《Planta》1991,184(2):175-181
InChlamydomonas eugametos gametes, phosphatidylinositol 4-phosphate (PtdInsP) and phosphatidylinositol 4,5-bisphosphate (PtdInsP2) comprised 0.4 and 0.3% of the whole-cell phospholipids. They were concentrated in the plasma membrane around the cell body and were present in low concentrations in the flagellar membrane. When gametes were fed32PO
4
-
, the label was rapidly incorporated into PtdInsP and PtdInsP2 and only slowly incorporated into structural lipids such as phosphatidylethanolamine and phosphatidylglycerol. Similarly, when a pulse of32PO
4
-
was chased with PO
4
-
, the label was rapidly lost from the polyphosphoinositol lipids but not from the structural lipids. The major fatty acids in the polyphosphoinositides were C-22 carbon polyenoic acids (70%). The significance of these results in relationship to intracellular signalling via inositol phosphates and Ca2+ is discussed.Abbreviations InsP3
inositol 1,4,5-trisphosphate
- mt–/mt+
mating-type plus or minus
- PtdA
phosphatidic acid
- PtdEtn
phosphatidylethanolamine
- PtdGro
phosphatidylglycerol
- PtdIns
phosphatidylinositol
- PtdInsP
phosphatidylinositol 4-phosphate;
- PtdInsP2
phosphatidylinositol 4,5-bisphosphate
- TCA
trichloroacetic acid
We thank Frank Schuring for Fig. 5A and Susan Kenter, Hans Kruisselbrink, Saskia Bijvank and Nelleke Corbett for their enthousiastic assistance. 相似文献
10.
J. E. Irvine G. T. A. Benda B. L. Legendre G. R. Machado Jr 《Plant Cell, Tissue and Organ Culture》1991,26(2):115-125
This study investigates the frequency of apparent and permanent expression of marker change following two types of tissue culture, conventional callus and direct regeneration cultures, and for two markers it relates this frequency to that following breeding. Each clone was used for only one marker. After conventional callus culture, plants of the sugarcane clone Arundoid B, a clone having a growth habit with shortened internodes and leaves, were freed of this marker at a rate of 1 in 172 plants. Marker remission in a second clone with a leaf blotch was enhanced in the presence of a mutagen. Callus culture alone gave a remission rate of 1/280 plants, while treatment of callus with ethyl methanesulfonate gave a remission rate of 1/42 plants. Of two markers subjected to vegetative and sexual transmission, the first, a leaf marker, was stable in callus culture with no remissions; crossing with non-marker parents produced progeny with 54% lacking the marker. The second, a stalk marker (multibud), showed epigenetic effects during two generations of vegetative propagation; plants lacking the multibud marker produced vegetative progeny in which the marker reappeared. Nine crosses to nonmarker parents produced progeny of which an average of 29% had the marker. The use of stalk chimeras as markers demonstrated that passage through conventional callus or direct regeneration culture resulted in the loss of the donor phenotype in all plants regenerated. Phenotypic variation in plants derived from callus culture appears to arise from several sources; chimeral segregants, epigenetic transients, and mutational variants. 相似文献