Simplified cervical spleen transplantation in rats using the cuff technique.
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Animals↗
Biomedical subjects
X H Li
Publications and source records attributed to X H Li.
High-resolution refinement of the hexagonal A-DNA octamer d(GTGTACAC) at 1.4 A.
The hexagonal crystal form of the octamer d(GTGTACAC), grown in the presence of spermine, has unit-cell dimensions a = b = 32.18 and c = 78.51 A, space group P6(1)22, with one DNA strand in the asymmetric unit. The structure has been refined starting with the earlier lower resolution model and using high-resolution 1.4 A data collected on a Siemens-Xentronics area detector at 258 K. There were 4365 unique reflections greater than 2sigma(F) in the resolution range 5-1.4 A. The model was refitted into 3F(o) - 2F(c). Sim-weighted omit maps and difference maps were used to locate water molecules. The final model with 161 DNA atoms and 37 water molecules gave an R factor of 19.8%. Crystals of the same octamer were also grown in the presence of spermidine instead of spermine, and refinement using nominal 1.45 A resolution data, 3292 unique reflections, final R = 19.1%, gave virtually identical DNA parameters. No bound spermine or spermidine was detected in either of these structure analyses. The electron density was clear for the DNA and showed holes in the center of the six-membered rings of bases, and also in the center of some of the sugar rings. The high-resolution structure has provided more precise DNA parameters and confirmed the features observed in the earlier 2 A study including the packing-induced distortion in the A7 (A15) sugar pucker from C(3')-endo and C(2')-endo. This change causes the end base pairs to bend away from the helix axis while the rest of the duplex is nearly linear. The hydration patterns in the deep and shallow grooves have been characterized. Chains of water molecules were found, but no rings. The familiar intermolecular contact region between the end base pair and the minor groove of a symmetry-related duplex, involving four residues on one strand and two on the other, has been analyzed. One of these interactions is a hydrogen bond.
Journal Article↗
Nuclear transport of tobacco etch potyviral RNA-dependent RNA polymerase is highly sensitive to sequence alterations.
The putative RNA-dependent RNA polymerase (NIb protein) of tobacco etch potyvirus accumulates primarily in the nucleus of infected cells, although viral RNA replication is suggested to occur in the cytoplasm. To understand the possible relationship between NIb nuclear localization and its function, we have studied translocation of NIb using gene fusion and plant transformation techniques. When expressed as a fusion with a cytoplasmic reporter protein, beta-glucuronidase (GUS), NIb efficiently directed transport to the nucleus in transgenic tobacco plants, confirming that NIb contains an independent nuclear translocation signal. The effects of site-directed substitutions and deletions in NIb were analyzed. Substitutions were targeted to three small clusters of basic amino acids that bear some resemblance to well-characterized nuclear localization signals (NLSs) of other karyophilic proteins. Amino acid changes affecting two clusters, between residues 3-5 and residues 303-306, abolished transport activity. However, the assignment of NLS function to these regions was complicated by the fact that substitutions at four additional sites throughout the NIb sequence also rendered the fusion protein primarily cytoplasmic. Each of six deletions in NIb debilitated nuclear localization, regardless of whether the basic clusters were deleted. Insertions of Pro-Pro dipeptides, which were predicted to induce protein folding aberrations, at three out of four positions in NIb reduced translocation. Taken together, these results suggest that nuclear localization activity of NIb may require a stringent tertiary structure in addition to one or more NLSs.
Amino Acid Sequence↗
Flavonoids from Koelreuteria henryi and other sources as protein-tyrosine kinase inhibitors.
The EtOH extract of Koelreuteria henryi was investigated in a search for natural products with potential protein-tryrosine kinase (PTK) inhibitory activity. The PTK inhibitory activity of the crude fractions was determined by measuring their inhibition of p56lck partially purified from bovine thymus using angiotensin I as a substrate. Analysis of those fractions that exhibited significant activity led to the isolation of kaempferol and quercetin, in addition to two kaempferol glycosides, kaempferol-O3-alpha-rhamnopyranoside [1] and kaempferol-O3-alpha-arabinopyranoside [2]. This study represents the first report on the isolation of flavonols and their PTK inhibitory activities from the genus Koelreuteria. Eight other flavonoids were also examined to study the role of the hydroxy groups on the B ring on PTK inhibitory activity.
Animals↗
[Preparation of medicated dental floss and the use of antioxidants].
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Antioxidants↗
[Prepare ideal temperature of water for mixing impression material].
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Dental Impression Materials↗
Rapid screening for taxanes by tandem mass spectrometry.
A highly specific and sensitive method is described for determining taxol, cephalomannine, and baccatin III in crude plant extracts. Radical anions of the taxanes are formed by desorption chemical ionization, and a parent tandem mass spectrometric scan is used to recognize these compounds by their characteristic dissociations. The limit of detection of the individual taxanes in typical plant matrices is less than 500 pg when all three species are screened simultaneously. Because of the sensitivity of the method, extraction times can be shortened to 30 min and crude extracts can be examined at the rate of 6/h. Detection of all three taxanes extracted from a single Taxus cuspidata needle in a combined extraction/analysis time of less than 1 h is demonstrated.
Alkaloids↗
In vivo accumulation of a turnip crinkle virus defective interfering RNA is affected by alterations in size and sequence.
Turnip crinkle virus is one of several single-stranded RNA plant viruses associated with defective interfering (DI) RNAs. A complete cDNA copy of a 344-base DI RNA (DI RNA G) was cloned downstream from a T7 RNA polymerase promoter. Transcripts synthesized in vitro were infectious when inoculated with helper virus on turnip plants. Studies of the infectivity of DI transcripts containing deletions, insertions, and single-base changes suggest that (i) in general, only the 5' two-thirds of the molecule can tolerate mutations; (ii) between 52 and 67 bases of terminal 5' sequence are required for infectivity; (iii) nucleotides in positions 68 to 138 are not specifically involved in RNA infectivity; (iv) DI RNA G molecules smaller than 327 bases are not amplified efficiently in plants.
Base Sequence↗
[Suppression of pituitary-adrenal axis by triamcinolone acetonide in asthmatics].
To assess the inhibitory effect of triamcinolone acetonide on pituitary-adrenal axis, we measured plasma cortisol, plasma ACTH and performed short ACTH stimulation test before and after injection of 40 mg of triamcinolone acetonide intramuscularly in 34 asthmatic patients. At the same time salivary cortisol levels had been followed up for four weeks in ten of the 34 patients. Maximum adrenal suppression was found in two to three days after the administration. The suppression rates of salivary cortisol, plasma cortisol, plasma ACTH and ACTH stimulation test were 81.5%, 53.2%, 70% and 45.6% respectively. Such suppression lasted for two weeks. Afterwards the secretion of pituitary and adrenal glands recovered gradually. The secretion of plasma ACTH and salivary cortisol returned to normal in four weeks and that of plasma cortisol in five weeks. Triamcinolone acetonide, 40 mg monthly, is comparable with prednisone 10 mg daily, or oral dexamethasone 0.75 mg daily. The inhibitory effect of the steroids on pituitary-adrenal axis was in the order of dexamethasone, triamcinolone acetonide and prednisone.
Adolescent↗
[Relationship between inhibitory action of tanshinone on neutrophil function and its prophylactic effects on myocardial infarction].
In isoprenaline-induced myocardial infarction in rabbits, the circulating neutrophils (neu) were in an activated state. tanshinone (tan, ig) suppressed the neu functions (acid-phosphatase release, adhesiveness, and phagocytosis) dose-dependently and reduced myocardial necrosis concomitantly. There was a positive correlation between neu functions and myocardial necrosis. In addition, tan caused an obvious decrease in content of lipoperoxide malondialdehyde in serum and myocardium, an increase in superoxide dismutase activity, an inhibition of leukocytic infiltration, and a production of prostaglandin E2 in myocardium. These effects were also related closely to the suppression of neu functions. Anti-inflammatory drug dexamethasone was used as control and had similar effects on Neu functions and myocardial infarction. It is suggested that the prophylactic effects of tan on myocardial infarction may result from the inhibition of circulating neu functions.
Abietanes↗
[Leukocyte and atherosclerosis].
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Alprostadil↗
Reduction of Na+ enhances phosphoinositide hydrolysis and differentiates the stimulatory and inhibitory responses to quisqualate in rat brain slices.
The concentration of Na+ in the incubation medium significantly influenced phosphoinositide hydrolysis induced by some, but not all, agonists in rat cerebral cortical slices. Reductions of the Na+ concentration below 120 mM resulted in incremental increases in basal and norepinephrine-stimulated accumulation of [3H]inositol monophosphate in cortical slices that had been prelabelled with [3H]inositol, and maximal responses were obtained with 0 and 5 mM Na+. In contrast, the responses to carbachol and ibotenate were similar in medium containing 120 or 5 mM Na+. In medium with 120 mM Na+, quisqualate has two effects on phosphoinositide hydrolysis in cortical slices, including a relatively weak stimulatory effect and an inhibitory modulation of the stimulation induced by norepinephrine. These two responses to quisqualate were differentially modulated by Na+; in 5 mM compared with 120 mM Na+ the stimulatory response was greatly increased and the inhibitory effect was mostly eliminated. That these were two separate events was confirmed by the use of L-BOAA (beta-N-oxalyl-L-alpha, beta-diaminopropionic acid), which reproduces the inhibitory, but not the stimulatory effect of quisqualate on phosphoinositide hydrolysis. In 5 mM Na+, inhibition by L-BOAA of norepinephrine-stimulated phosphoinositide hydrolysis was completely eliminated. These results demonstrate that a physiological concentration of Na+ maintains phosphoinositide hydrolysis at a submaximal level of sensitivity to some, but not all, agonists. The differential effects of Na+ on the stimulatory and inhibitory effects of quisqualate further substantiate the suggestion that these are two separate processes and indicate that alterations of the Na+ concentration may influence the effects of quisqualate, and other agonists, on phosphoinositide hydrolysis.
Animals↗
Modulation of phosphoinositide metabolism in rat brain slices by excitatory amino acids, arachidonic acid, and GABA.
In rat brain slices the synthesis of [3H]phosphoinositides and the production of [3H]inositol monophosphate (IP1) induced by norepinephrine (NE) were inhibited by glutamate. Calcium concentrations were varied to test if these inhibitory effects of glutamate were mediated by a calcium-dependent process. Although reducing calcium or addition of the calcium antagonist verpamil reduced the inhibitory effects of glutamate, these results were equivocal because reduced calcium directly decreased agonist-induced [3H]phosphoinositide synthesis. The inhibitory effects of glutamate were mimicked by quisqualate in a dose-dependent manner, but none of a variety of excitatory amino acid receptor antagonists modified the inhibition caused by quisqualate. It is suggested that glutamate activates a quisqualate-sensitive receptor (for which an antagonist is not available) and causes inhibition of phosphoinositide hydrolysis mediated in part by a direct or indirect inhibitory effect of calcium on phosphoinositide synthesis. Modulatory effects of arachidonic acid were examined because glutamate and calcium can activate phospholipase A2. Arachidonic acid caused a rapid and dose-dependent inhibition of [3H]phosphoinositide synthesis and of NE-stimulated [3H]IP1 production. A similar inhibition of the response to carbachol also occurred. The inhibition caused by arachidonic acid was unchanged by addition of inhibitors of cyclooxygenase or lipoxygenase. Activation of phospholipase A2 with melittin caused inhibitory effects similar to those of arachidonic acid. Inhibitors of phospholipase A2 were found to impair phosphoinositide metabolism, likely due to their lack of specificity for phospholipase A2. Further studies were carried out in slices that were prelabelled with [3H]inositol in an attempt to separate modulatory effects on [3H]phosphoinositide synthesis and agonist-stimulated [3H]IP1 production. Several excitatory amino acid agonists inhibited NE-stimulated [3H]IP1 production. This inhibitory interaction could be due to impaired synthesis of [3H]phosphoinositides because, even though the slices were prelabeled, addition of unlabelled inositol reduced NE-stimulated [3H]IP1 production, indicating that continuous regeneration of [3H]phosphoinositides is required. In contrast to the inhibitory effects of the excitatory amino acids, gamma-aminobutyric acid (GABA) enhanced the response to NE in cortical and hippocampal slices. GABA also enhanced the response to carbachol in hippocampal and striatal slices and to ibotenic acid in hippocampal slices. Baclofen potentiated the response to NE similarly to the effect of GABA and baclofen partially blocked the inhibitory effect of arachidonic acid but did not alter that of quisqualate.
Amino Acids↗
Alpha-1 adrenergic receptor binding and adrenergic-stimulated cyclic AMP production in rat cerebral cortex after chronic lithium treatment.
Administration to rats of dietary lithium for 30 days was followed by evaluation of alpha-1 adrenergic receptor binding and of adrenergic-stimulated cyclic AMP (cAMP) accumulation in rat cerebral cortex. Chronic lithium treatment did not alter the binding characteristics of [3H]prazosin or the proportion of alpha-1 adrenergic receptor subtypes distinguished by chlorethyl-clonidine (CEC) pretreatment in rat cerebral cortical membranes. Accumulation of cAMP in cortical slices incubated with adrenergic agonists was unaffected in lithium-treated rats. These results demonstrate that chronic lithium treatment-induced reduction of norepinephrine (NE)-stimulated phosphoinositide (PI) hydrolysis (Casebolt and Jope, 1987) is not due to changes in the alpha-1 adrenergic receptor and is more sensitive to in vivo lithium treatment than is adrenergic-stimulated cAMP accumulation.
Administration, Oral↗
Recombination between satellite RNAs of turnip crinkle virus.
Turnip crinkle virus (TCV) is associated with satellite (sat) RNAs (sat-RNA D, sat-RNA F), defective interfering (DI) RNAs (DI RNA G, DI1 RNA), and one RNA with properties of both sat-RNAs and DI RNAs (sat-RNA C). When plants were inoculated with TCV, sat-RNA D and in vitro sat-RNA C transcripts containing non-viable mutations in the 5' domain, recombinant sat-RNAs were recovered. These recombinants were composed of sat-RNA D at the 5' end and sat-RNA C sequences at the 3' end. Analysis of 20 independent recombination junctions revealed that unequal crossing-over had occurred in planta in a region of sequence similarity between the two sat-RNAs which resulted in the duplication of 3-16 nucleotides. Thirty percent of the sat-RNA recombinants also had one to three additional nucleotides inserted at the crossover junctions which did not correspond to either sat-RNA C or sat-RNA D sequence. The right side of the recombination junctions always began with one of three consecutive nucleotides of sat-RNA C. Based on the similarity between this sequence of sat-RNA C, the right side junction of DI RNA G and the 5' end of TCV, as well as the sequence similarity between right side junctions of DI1 RNA and sat-RNA C and the 5' end of the sat-RNAs, a replicase-driven copy choice mechanism is proposed.(ABSTRACT TRUNCATED AT 250 WORDS)
Base Sequence↗
[Significance of serum procollagen-III-peptide in reflecting the therapeutic effects of calcium-channel blockers on hepatic fibrosis].
Changes in serum procollagen-III-peptide (PIIIP) and intravenous tryptophan tolerance test (ITT) were studied in 121 patients with liver cirrhosis during a follow-up period of up to 18 months. The patients received either nifedipine (31 cases, 60 mg/day), verapamil (28 cases, 120 mg/day), cinnarizine (29 cases, 150 mg/day) or tetrandrine (33 cases, 150 mg/day). The significant changes were found in ITT in any of the four drugs administrated for over three months. Serum PIIIP concentration decreased significantly in patients under tetrandrine therapy for 18 months (12.06 +/- 3.91 ng/ml vs 16.57 +/- 5.69 ng/ml before treatment). These data suggest that tetrandrine therapy may have favourable effects on hepatic fibrosis and improvement of liver function in liver cirrhosis.
Adult↗
High frequency plant regeneration from protoplasts of wheat.
Calli were initiated from the mature seeds of wheat (Triticum asetivum L.cv. Xuzhou 211), and suspension cultures were established. The protoplasts isolated from suspension cells were cultured in the modified MS medium solidified with 0.8% agarose. Regenerated cells divided and calli formed. Whole plants were regenerated from protoplast-derived calli. Colony formation was promoted when the medium with lower osmotic pressure was added after two weeks culture. The frequency of regenerated plants was increased with lower concentration of sucrose in the differentiation medium. Shoots were induced effectively with high concentration of cytokinins and calliferous shoots were avoided. The frequency of regenerated plants was affected when protoplast-derived calli were transferred onto the differentiation medium in different periods.
Cells, Cultured↗
Structural characterization of the manganese(IV) Schiff-base complex MnIV(5-Cl-SALAHP)2.
Bis[3-(5-chlorosalicylideneamino)propanolato-O,N,O']manganes e(IV) methanol solvate, [Mn(C10H10ClNO2)2].CH3OH, Mr = 510.3, monoclinic, P2(1)/c, a = 11.949 (2), b = 7.530 (2), c = 25.777 (6) A, beta = 105.75 (2) degrees, V = 2232.4 (8) A3, Z = 4, Dx = 1.518 g cm-3, lambda(Mo K alpha) = 0.7107 A, mu = 7.98 cm-1, F(000) = 1502, T = 300 K, R = 0.0343, wR = 0.032 for 2113 unique reflections with (I) greater than 3 sigma(I). The title complex MnIV(5-Cl-SALAHP)2 [5-Cl-SALAHP = 3-(5-chlorosalicylideneamino)propanolato] displays a regular octahedral geometry. The 5-Cl-SALAHP ligand is tridentate, forming a meridional chelate with one phenolato oxygen (Mn-Oavg = 1.90 A), one alkoxide oxygen (Mn-Oavg = 1.85 A) and one imine nitrogen (Mn-Navg = 2.02 A) coordinated to the metal. Important angles described by the six atoms bound to manganese are all very close to either 180 or 90 degrees except the N-Mn-N angle which is 174.7 degrees. Previous studies have shown that MnIV(5-Cl-SALAHP)2 displays a rhombic EPR spectrum with well-resolved 55Mn hyperfine structure on gx, gy and gz. In contrast, Mn(SALADHP)2 [SALADHP = 2-methyl-2-(salicylideneamino)-1,3-propanediolato] shows a broad, ill-defined signal at g = 5.15 and a weak g = 2 component. The different spectral forms result from the extent of distortion of the MnIV octahedron. The reported structure is of potential importance to the understanding of the photosynthetic water-oxidizing system.
Chemical Phenomena↗