Magnetic, thermal, transport, and structural properties of Sr2RuO4+ delta : Enhanced charge-carrier mass in a nearly metallic oxide.
Explore the source record for details and available documents.
Journal Article↗
Biomedical subjects
H Xie
Publications and source records attributed to H Xie.
Zinc is an inhibitor of the stimulatory response of the sodium efflux to the microinjection of cyclic AMP and forskolin in single barnacle muscle fibers.
The main aim of the experiments with which this paper deals was to test the hypothesis that Zn is an inhibitor of the stimulatory response of the ouabain-insensitive component of the Na efflux to the injection of cAMP, DcAMP (dibutyryl-cAMP) and FD (forskolin derivative) in barnacle muscle fibers. The results obtained were as follows: (1) External application of Zn caused a fall in the Na efflux in fibers poisoned with ouabain beforehand; (2) external application of Zn prior to the injection of cAMP, DcAMP and FD led to a marked reduction in the response of the Na efflux in fibers pre-treated with ouabain; (3) the response obtained by the injection of DcAMP and FD into ouabain-poisoned fibers pre-exposed to Zn was small but sustained; and (4) external application of Zn following peak stimulation by injecting DcAMP or FD led to reversal of this response. (Parallel experiments involving the injection of cAMP were not done, since the response following the onset of peak stimulation decays quite rapidly.) Taken together, these results support the hypothesis that Zn behaves as an inhibitor of the stimulatory response obtained by the injection of cAMP, DcAMP and FD.
Animals↗
An enzymatic activity in bovine brain that catalyzes the reversal of the C-terminal methyl esterification of protein phosphatase 2A.
A novel protein methyltransferase has been recently described that catalyzes the esterification of the C-terminal leucine residue of the catalytic subunit of protein phosphatase 2A in a variety of eucaryotic cells. This reaction can potentially modulate the phosphatase's activity, subunit interactions, or interactions with specific phosphoprotein substrates. We present evidence here that the methylation reaction is reversible and that an enzymatic activity is present in bovine brain cytosol that catalyzes the hydrolysis of the methyl ester. We show that this activity is sensitive to inhibition by the serine-hydrolase inhibitor phenylmethanesulfonyl fluoride but is not affected by the small molecule substrate analog N-acetyl-L-leucine methyl ester. These results suggest that protein methylation and demethylation reactions can be utilized in eucaryotic cells to modulate enzyme activity in a parallel fashion to protein phosphorylation and dephosphorylation reactions.
Animals↗
Protein phosphatase 2A is reversibly modified by methyl esterification at its C-terminal leucine residue in bovine brain.
We have recently described a novel protein carboxyl methylation system that results in the reversible modification of a 36-kDa polypeptide component of a 178-kDa protein in the cytosol of a variety of eucaryotic cells. This reaction, catalyzed by a cytosolic 40-kDa methyl-transferase, results in the methyl esterification of the alpha-carboxyl group of the C-terminal leucine residue. We have now purified the major methylated 36-kDa polypeptide from bovine brain. N-terminal sequence analysis of a tryptic fragment of this polypeptide revealed identity to the catalytic subunit of protein phosphatase 2A. This enzyme exists in the cell predominantly as a trimeric 151-kDa native species containing the 36-kDa catalytic polypeptide that terminates in a leucine residue. We then fractionated bovine brain cytosolic extracts to separate the major phosphatase isoforms 2A1 and 2A2 and found that both could be methylated by a partially purified preparation of the methyltransferase. A synthetic C-terminal octapeptide based on the sequence of the 36-kDa catalytic subunit is neither a substrate nor an inhibitor of this methyltransferase, suggesting that this enzyme recognizes aspects of the tertiary and/or quaternary structure of the native phosphatase. Because this modification reaction is readily reversible in extracts, it may represent a novel strategy of the cell to modulate the function of this protein phosphatase.
Animals↗
Use of a new technique to map the porcine alpha interferon gene to chromosome 1.
Explore the source record for details and available documents.
Animals↗
Human anti-(murine Ig) antibody responses in patients with hepatocellular carcinoma receiving intrahepatic arterial 131I-labeled Hepama-1 mAb. Preliminary results and discussion.
Human anti-(murine Ig) antibody (HAMA) responses were monitored in 32 patients with unresectable hepatocellular carcinoma (HCC) undergoing radioimmunotherapy using 131I-labeled anti-HCC monoclonal antibody (Hepama-1 mAb) intrahepatic arterial infusion. Dosages of Hepama-1 mAb ranged from 5 mg to 20 mg and the mAb was radiolabeled with 0.74-4.00 GBq (20-108 mCi) 131I (4-6 mCi/mg). T lymphocyte subsets were examined before and after radioimmunotherapy in 24 patients. In this series, 34.4% (11/32) of patients developed HAMA within 2-4 weeks after the infusion. All patients with a negative HAMA response (n = 14), had CD4+ T lymphocyte subsets (T helper/inducer) much lower than those of the HAMA-positive (n = 10) patients and the control group (n = 40) (P < 0.01) prior to infusion. The sequential resection and survival rates in the HAMA-negative group were also lower than that of the HAMA-positive group. Thus, the determination of T lymphocyte subsets might help to predict the HAMA response in HCC patients during radioimmunotherapy.
Adult↗
The effects of streptozotocin diabetes on salivary-mediated bacterial aggregation and adherence.
Diabetic rats are known to have an increased susceptibility to dental caries and major alterations in parotid salivary composition. Salivary proteins play an important part in oral health maintenance; thus specific changes in salivary protein composition in diabetic animals might alter the ecological balance in favour of cariogenic bacteria, and toward the initiation and progression of the disease process. The ability of whole, parotid and submandibular salivas from control and streptozotocin-diabetic rats to mediate the aggregation and adherence to hydroxyapatite of mutans streptococci was examined. Salivary-mediated bacterial aggregating activity was significantly reduced in whole and parotid salivas from diabetic rats, but bacterial adherence to hydroxyapatite was unaffected. The aggregating and adherence activities of rat whole saliva were derived mainly from parotid saliva, which contains predominantly low molecular-weight proteins and glycoproteins (< 200 kDa), but rat parotid saliva was capable of interacting with the bacterial receptor for the high molecular-weight aggregating factor in human saliva. SDS-PAGE of parotid saliva revealed that a number of proteins, including the basic and acid proline-rich proteins, were altered in the salivas of diabetic animals. After incubation with either Streptococcus mutans or hydroxyapatite several protein bands were depleted, and thus a variety of proteins and glycoproteins may be responsible for the adherence and aggregating activity of rat parotid saliva.
Analysis of Variance↗
Molecular phylogenetic studies on filarial parasites based on 5S ribosomal spacer sequences.
This paper is the first large-scale molecular phylogenetic study on filarial parasites (family Onchocercidae) which includes 16 species of 6 genera: Brugia beaveri Ash et Little, 1962, B. buckleyi Dissanaike et Paramananthan, 1961; B. malayi (Brug, 1927) Buckley, 1960; B. pahangi (Buckley et Edeson, 1956) Buckley, 1960; B. patei (Buckley, Nelson et Heisch, 1958) Buckley, 1960; B. timori Partono et al, 1977; Wuchereria bancrofti (Cobbold, 1877) Seurat, 1921: W. kalimantani Palmieri. Purnomo, Dennis and Marwoto, 1980: Mansonella perstans (Manson, 1891) Eberhard et Orihel, 1984; loa loc, Stiles, 1905; Onchocerca volvulus (Leuckart, 1983) Railliet er Henry, 1910; O. ochengi Bwangamoi, 1969; O. gutturosa Neumann, 1910; Dirofilaria immitis (Leidy, 1856) Railliet e Henry, 1911; Acanthocheilonema viteae (Krepkogorskaya, 1933) Bain, Baker et Chabaud, 1982 and Litomosoides sigmodontis Chandler, 1931. 5S rRNA gene spacer region sequence data were collected by PCR, cloning and dideoxy sequencing. The 5S rRNA gene spacer region sequences were aligned and analyzed by maximum parsimony algorithms, distance methods and maximum likelihood methods to construct phylogenetic trees. Bootstrap analysis was used to test the robustness of the different phylogenetic reconstructions. The data indicated that 5S spacer region sequences are highly conserved within species yet differ significantly between species. Spliced leader sequences were observed in all of the 5S rDNA spacers with no sequence variation, although flanking region sequence and length heterogeneity was observed even within species. All of the various tree-building methods gave very similar results. This study identified four clades which are strongly supported by bootstrap analysis the Brugia clade; the Wuchereria clade; the Brugia-Wuchereria clade and the Onchocerca clade. The analyses indicated that L. sigmodontis and A. viteae may be the most primitive among the 16 species studied. The data did not show any close relationship between Loa loa and D. immitis presently classified in the same subfamily, and the constitution of the Dirofilariinae subfamily is questionable.
Algorithms↗
Molecular phylogenetic studies on Brugia filariae using Hha I repeat sequences.
This paper is the first molecular phylogenetic study on Brugia parasites (family Onchocercidae) which includes 6 of the 10 species of this genus: B. beaveri Ash et Little, 1964; B. buckleyi Dissanaike et Paramananthan, 1961: B. malayi (Brug, 1927) Buckley, 1960; B. pahangi (Buckley et Edeson, 1956) Buckley, 1960; B. patei (Buckley, Nelson er Heisch, 1958) Buckley, 1960 and B. timori Partono et al., 1977. Hha l repeat sequences are 322 nucleotides long, highly repeated, tandemly arranged and unique to the nuclear genomes of the genus Brugia. Hha l repeat sequence data was collected by PCR, cloning and dideoxy sequencing. The Hha l repeat sequences were aligned and analyzed by maximum parsimony algorithms, distance methods and maximum likelihood methods to construct phylogenetic trees. Bootstrap analysis was used to test the robustness of the different phylogenetic reconstructions. The data indicated that the Hha l repeat sequences are highly conserved within species yet differ significantly between species. The various tree-building methods gave identical results. Bootstrap analyses on the Hha l repeat sequence data set identified at least two clades: the B. pahangi-B. beaveri clade and the B. malayi-B. timori-B. buckleyi clade; the first clade includes parasites of carnivores from Asia and America; the second includes species from primates and lagomorphs from Asiatic region. It was also noted that the Hha l repeat sequences obtained from B. malayi were identical to those obtained from B. timori, indicating very recent speciation.
Algorithms↗
Epidermal growth factor receptor-mediated cell motility: phospholipase C activity is required, but mitogen-activated protein kinase activity is not sufficient for induced cell movement.
We recently have demonstrated that EGF receptor (EGFR)-induced cell motility requires receptor kinase activity and autophosphorylation (P. Chen, K. Gupta, and A. Wells. 1994. J. Cell Biol. 124:547-555). This suggests that the immediate downstream effector molecule contains a src homology-2 domain. Phospholipase C gamma (PLC gamma) is among the candidate transducers of this signal because of its potential roles in modulating cytoskeletal dynamics. We utilized signaling-restricted EGFR mutants expressed in receptor devoid NR6 cells to determine if PLC activation is necessary for EGFR-mediated cell movement. Exposure to EGF (25 nM) augmented PLC activity in all five EGFR mutant cell lines which also responded by increased cell movement. Basal phosphoinositide turnover was not affected by EGF in the lines which do not present the enhanced motility response. The correlation between EGFR-mediated cell motility and PLC activity suggested, but did not prove, a causal link. A specific inhibitor of PLC, U73122 (1 microM) diminished both the EGF-induced motility and PLC responses, while its inactive analogue U73343 had no effect on these responses. Both the PLC and motility responses were decreased by expression of a dominant-negative PLC gamma-1 fragment in EGF-responsive infectant lines. Lastly, anti-sense oligonucleotides (20 microM) to PLC gamma-1 reduced both responses in NR6 cells expressing wild-type EGFR. These findings strongly support PLC gamma as the immediate post receptor effector in this motogenic pathway. We have demonstrated previously that EGFR-mediated cell motility and mitogenic signaling pathways are separable. The point of divergence is undefined. All kinase-active EGFR mutants induced the mitogenic response while only those which are autophosphorylated induced PLC activity. U73122 did not affect EGF-induced thymidine incorporation in these motility-responsive infectant cell lines. In addition, the dominant-negative PLC gamma-1 fragment did not diminish EGF-induced thymidine incorporation. All kinase active EGFR stimulated mitogen-activated protein (MAP) kinase activity, regardless of whether the receptors induced cell movement; this EGF-induced MAP kinase activity was not affected by U73122 at concentrations that depressed the motility response. Thus, the signaling pathways which lead to motility and cell proliferation diverge at the immediate post-receptor stage, and we suggest that this is accomplished by differential activation of effector molecules.
Base Sequence↗
The endothelium contributes to the contractile responses of the human umbilical artery to 5-hydroxytryptamine and endothelin-1 under low but not high PO2 conditions.
To determine the influences of both PO2 and the presence of the endothelium on contractile responses of the human umbilical artery (HUA), the effects of a series of vasoconstrictors were compared in ring preparations with and without endothelium at low (2.5% O2, PO2 < 55 mmHg (1 mmHg = 133.3 Pa)) and high PO2 (95% O2, PO2 > 600 mmHg). The results demonstrate the following. (i) 5-Hydroxytryptamine (5-HT) and endothelin-1 (ET-1) contracted the HUA at either low or high PO2. At low PO2, removal of the endothelium significantly reduced receptor-mediated responses. (ii) The nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 100 microM) did not modulate 5-HT-initiated contractions at either level of PO2. (iii) alpha-Methyl-5-hydroxytryptamine (alpha-Me-5-HT) and 5-carboxamidotryptamine (5-CT), relatively selective 5-HT1C/5-HT2 and 5-HT1-like receptor agonists, respectively, elicited contractions in the HUA, and the responses were reduced at low PO2 but unaffected by removal of the endothelium. (iv) Responses of the HUA to high potassium (hK+) were unaffected by either changes in PO2 or removal of the endothelium. (v) The 5-HT2 receptor antagonist ketanserin at low concentration (10 nM) inhibited contractile responses to 5-HT in an apparently competitive manner. However, with 100 nM ketanserin and at low PO2, inhibition became noncompetitive. Removal of the endothelium did not influence the action of ketanserin. (vi) Regardless of PO2, the Ca2+ channel antagonist nifedipine (1 microM) significantly inhibited 5-HT- and ET-1-mediated contractions.(ABSTRACT TRUNCATED AT 250 WORDS)
Arginine↗
Use of direct in situ single-copy (DISC) PCR to physically map five porcine microsatellites.
Direct in situ single-copy polymerase chain reaction (DISC-PCR) was used to assign and orient a linkage group to pig chromosome 1. Five microsatellites were analyzed, and all five were successfully localized using this procedure. Physical data were used to orient the linkage group with respect to the centromere and estimate the amount of coverage of chromosome 1. There was excellent concordance between the physical and linkage maps. The linear order of the microsatellites was identical, and relative distances were similar. All markers were located on the long arm of chromosome 1. Coverage was estimated at about 32%. Thus, DISC-PCR rapidly and easily assigned and ordered microsatellite markers for which large genomic clones do not exist.
Animals↗
Characteristics of acupuncture meridians and acupoints in animals.
In recent years, an increasing number of studies has been conducted on the biophysical characteristics of the meridians and acupoints in humans and animals. The authors aim to further illustrate the objective existence and superficial locations of the meridians in various species of animals. Twelve sheep, ten goats, thirteen pigs, eleven cats, eight rabbits and seven donkeys were used to measure low impedance lines (LILs) and high percussion sound lines (HPSLs) on the skin surface of the animals, along the vertical planes of the dorsal line, using electrical impulses and high percussion sound. The results of these studies are given.
Acupuncture Points↗
Effects of total coumarins of Fructus cnidii on skeleton of ovariectomized rats.
Total coumarins of Fructus Cnidii (TCFC), 5 g.kg-1 by intragastric gavage, 6 d/wk, x 7 wk, was effective for prevention of bone loss in ovariectomized (OVX) rats. In comparison to aging control rats, the proximal tibia of placebo-treated OVX rats were characterized by an increase in eroded perimeter (+298%), label perimeter (+77%), osteoid perimeter (+47%), mineral apposition rate (+32%) and bone formation rate (+130%). These changes indicated a high bone turnover in OVX rats leading to a rapid bone loss (-44%) in proximal tibial metaphysis. In contrast, the TCFC-treated OVX rats showed an increase of cancellous bone area (+41%) compared with placebo-treated OVX rats and decrease in all the above indices of bone turnover to near aging control levels except that of the osteoid area (+88%) which was higher than that in aging control, but mineralization lag time did not show significant changes. The results suggested that the TCFC inhibited the high bone turnover and reversed the bone loss at early menopausal stage.
Animals↗
Studies on the condition of fermentation of pullulan by Aureobasidium pullulans.
Studies on optimal conditions for pullulan fermentation based on the results obtained from a shaking flask were carried out in a 16-L auto-controlling fermentor. It found that the optimal DE value of starch hydrolyzate was 40-50 when 10% starch hydrolysate was used as carbon source. The optimal concentration of ammonium sulfate in the medium for fermentation was different from that of the shaking flask. The fermentation kinetics and effects of seed age, seed volume, airflow rate, pressure of tank, agitation speed and number of vane group on the production of pullulan were investigated.
Biomass↗
[Effect of total coumarins from dried fruits of Cnidium monnieri on glucocorticoid-induced osteoporosis in rats].
Twenty-four 3-month-old male SD rats were divided into 3 groups: Group 1--control (ig water). Group 2--ig prednisone 45 micrograms.kg-1 twice a week. Group 3--treated with total coumarins of dried fruits of Cnidium monnieri (L) Cuss (TCCM) and prednisone. TCCM was given ig 5 g.kg-1, 6 days per week. After 90 d, rats were killed. The proximal tibiae of rats were processed undecalcified for histomorphometric analysis. In comparison with control rats, the bone resorption was enhanced and bone formation decreased. The trabecular bone areas were characterized by reduction of 40% in rats which received prednisone. Trabecular bone areas of rats treated with TCCM increased 56% compared with rats receiving prednisone. All indices of bone histomorphometry were near to those in the control. The results showed that TCCM prevented glucocorticoid-induced osteoporosis.
Animals↗
[Cyclocryotherapy for refractory glaucoma after penetrating keratoplasty].
Twenty-eight patients (28 eyes) with secondary glaucoma following penetrating keratoplasty and failed to respond to anti-glaucoma drugs and routine filtering procedures were performed with cyclocryotherapy by nitrogen monoxide. All patients were followed up for more than one year. The results showed intraocular pressure was well controlled in 89% of the eyes, graft remained clear in 85%, and visual functions are preserved in 82% of the patients. Our study suggests that precisely controlled temperature, time, and extent of cryotherapy, and post-operative anti-rejection agents be the key factor to success. Over-treatment, which may lead to atrophy of the eye, must be avoided. It should not be given up flowing under-treatment in the initial procedure.
Adolescent↗
Acetylcholine relaxes the human umbilical artery by an endothelium-independent but ouabain and tetraethylammonium-sensitive process.
Explore the source record for details and available documents.
Acetylcholine↗