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X Su

Publications and source records attributed to X Su.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Extraction and purification of acidic mucopolysaccharide from Holothuria atra].

Mucopolyaccharide with molecular weight of 10253 Da was extracted and purified from fresh Holothuria atra Jaeger by means of enzymic and alkaline hydrolysis, potassium acetate and ethanol fractional precipitation. It was tested to be purified ingredient with agarose electrophoresis. The percentage content of galactosamine, glucuronic acid, fucose and sulfate in the mucopolysaccharide was 16.12%, 17.88%, 11.66% and 23.52% respectively.

Animals↗
PubMed1998

Caldesmon inhibits active crossbridges in unstimulated vascular smooth muscle: an antisense oligodeoxynucleotide approach.

Caldesmon is a thin-filament-associated protein believed to be important in the regulation of smooth muscle contraction, although the precise mechanism is unknown. We used antisense oligodeoxynucleotides to produce intact swine carotid smooth muscle tissue deficient in h-caldesmon. Caldesmon content was decreased by 78% after 7 days in culture with antisense oligodeoxynucleotides but was unchanged in tissues in the presence of sense oligodeoxynucleotides or vehicle. Antisense oligodeoxynucleotides produced a significant decrease in the caldesmon/actin ratio, but no change was measured in the calponin/actin ratio, suggesting that the effect was specific to caldesmon and not other thin-filament-associated proteins. Basal and KCl-stimulated levels of myosin light chain phosphorylation were not different among tissues from all 3 groups. In contrast, h-caldesmon-deficient tissues produced 62% less KCl-induced force than controls. Unstimulated h-caldesmon-deficient smooth muscle tissues stretched and then released, redeveloped force, demonstrating active crossbridge cycling; strips containing normal h-caldesmon content did not redevelop force on release. We suggest that in resting vascular smooth muscle, active crossbridges are inhibited by caldesmon. Therefore, regulation of smooth muscle includes a thin-filament-based disinhibition component.

Animals↗
PubMed1998

Autocrine and paracrine apoptosis are mediated by differential regulation of Fas ligand activity in two distinct Jurkat T cell populations.

Fas ligand (FasL) produced by activated T cells mediates autocrine-induced apoptosis to limit T cell expansion. To investigate the regulation of FasL activity, Jurkat cells were stably transfected with a 2.3-kb fragment of human FasL promoter that controlled the expression of a GFP reporter gene. Two populations of Jurkat cells with different levels of GFP expression were obtained. One population constitutively expressed high levels of GFP (GFP+), while the other population expressed low levels of GFP (GFP-). The level of GFP expression in the two populations correlated with their levels of FasL transcription and its functional activity. Autocrine regulation of apoptosis was demonstrated by increased FasL activity after stimulation of GFP- cells with anti-CD3, phorbyl myristyl acetate plus ionomycin, or Con A. Paracrine regulation of apoptosis was suggested by the induction of apoptosis of GFP- cells after coculture with unstimulated GFP+ cells. GFP+ cells exhibited a decreased sensitivity to FasL-mediated apoptosis compared with GFP- cells. Furthermore, the cell surface expression of Fas and CD4 was lower on GFP+ cells than GFP- cells, whereas the expression of CD45RO was higher. A decreased level of IL-2 was produced by GFP+ cells after phorbyl myristyl acetate and ionomycin stimulation. Our results indicate that a subpopulation of T cells that express low levels of FasL and IL-2, which are responsive to up-regulation of these molecules after activation, can undergo apoptosis either by suicide after activation or by a paracrine pathway mediated by T cells that constitutively express higher levels of FasL.

Apoptosis↗
PubMed1998

Reduction of arthritis and pneumonitis in motheaten mice by soluble tumor necrosis factor receptor.

OBJECTIVE: To determine the effects of anti-tumor necrosis factor (anti-TNF) therapy in the inflammatory and autoimmune disease in motheaten (me/me) mice, which exhibit a Fas apoptosis signaling defect. METHODS: Arthritis, pneumonitis, and mortality were analyzed in me/me mice treated with a novel, soluble, dimeric TNF receptor I (sTNFRI) molecule capable of high-affinity binding and neutralization of TNFalpha. RESULTS: Soluble TNFRI reduced serum levels of TNFalpha and led to a 2-fold increase in the lifespan of me/me mice, compared with the control treatment group. The treatment also reduced the development of the "motheaten" skin patches and alleviated pneumonitis and inflammatory lesions in the extremities of me/me mice compared with controls. However, the serum levels of IgM and IgM anti-double-stranded DNA autoantibody were comparable to those of untreated control mice. CONCLUSION: TNFalpha is an important cytokine involved in the pathogenesis of inflammatory disease in me/me mice, resulting in tissue damage and early mortality. Therapies directed at blocking TNF/TNFR interactions, such as the sTNFRI used in these experiments, may be effective in diseases associated with apoptosis defects leading to overutilization of the TNF/TNFR pathway.

Alopecia↗
PubMed1998

Cervical ripening in the third trimester of pregnancy with intravaginal misoprostol: a double-blind, randomized, placebo-controlled study.

To evaluate the safety and efficacy of intravaginal misoprostol for cervical ripening in the third trimester, a randomized, double-blind, placebo-controlled trial was conducted in 85 patients indicated for induction of labor and with unfavorable cervices. They were randomly assigned to receive either intravaginal misoprostol (100 mg) or placebo placed in the posterior vaginal fornix. The Bishop score, fetal heart rate and Doppler blood flow velocity waveforms were measured before and 12 h after drug administration. Placenta and decidu were histopathologically observed in some cases. Among 85 patients enrolled, 43 received misoprostol and 42 received placebo. Whereas the mean initial Bishop scores were not significantly different between the two groups, the mean Bishop score in misoprostol group was significantly better than those in placebo group. The mean change in Bishop score was also significantly different (4.4 for misoprostol versus 1.0 for placebo, P < 0.01). The prevalence of spontaneous onset of labor within 12 h after drug insertion in misoprostol group (67.4%, 29/43) was significantly higher than that in placebo group (14.3%, 6/42), P < 0.01. The average Doppler velocity systolic to diastolic (S/D) ratios of umbilical artery, middle cranial artery, renal artery were not significantly different before and 12 h after drug insertion between both groups. There was no significant difference in frequency of abnormal fetal heart rate tracings or fetal distress and in the mean Apgar scores between the two groups. Except the presence of vasodilation in villi vessels in the misoprostol group, the placental and decidual histopathological changes had no significantly difference between two groups. It is concluded that intravaginal misoprostol may be an effective and safe cervical ripening agent in the third trimester of pregnancy.

Administration, Intravaginal↗
PubMed1998

Sterol synthesis. Synthesis of 3 beta-hydroxy-25,26,26,26,27,27,27-heptafluorocholest-5-en-7-one and its effects on HMG-CoA reductase activity in Chinese hamster ovary cells, on ACAT activity in rat jejunal microsomes, and serum cholesterol levels in rats.

3 beta-Hydroxycholest-5-en-7-one (I; 7-ketocholesterol) is an oxysterol of continuing interest in biology and medicine. In the present study, we have prepared a side-chain fluorinated analog, 3 beta-hydroxy-25,26,26,26,27,27,27-heptafluorocholest-5-en-7-one (VI), with the anticipation that the F7 substitution would block major metabolism of the 7-ketosterol, and thereby enhance its potential in vivo effects on serum cholesterol levels and other parameters. Chromium trioxide/dimethyl pyrazole oxidation of the acetate derivative of the previously described 25,26,26,26,27,27,27-heptafluorocholest-5-en-3 beta-ol (Swaminathan et al., 1993. J. Lipid Res. 34, 1805-1823) followed by mild alkaline hydrolysis gave VI. The effects of VI on 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity in Chinese hamster ovary (CHO-K1) cells, on acyl coenzyme A-cholesterol acyltransferase (ACAT) activity in rat jejunal microsomes, and on serum cholesterol levels and other parameters in male Sprague-Dawley rats were determined and compared with those obtained with I and with another alpha, beta-unsaturated ketosterol, i.e. 3 beta-hydroxy-5 alpha-cholest-8(14)-en-15-one (II). I and VI showed essentially the same potency, considerably less than that of II, in lowering the levels of HMG-CoA reductase activity in CHO-K1 cells. Whereas addition of II to rat jejunal microsomes inhibited ACAT activity (IC50 approximately 3 microM), I and VI had no effect under the conditions studied (from 1 to 16 microM). Dietary administration of I, at levels of 0.1 and 0.15%, had no effect on food consumption, gain in body weight, or serum cholesterol levels. At 0.2%, I caused a modest decrease in body weight gain and a slight decrease in serum cholesterol levels (relative to ad libitum but not pair-fed control animals). The F7-7-ketosterol VI, at 0.26% in diet (the molar equivalent of 0.2% I), had no effect on food consumption, body weight, or serum cholesterol levels. Administration of I (0.1, 0.15 or 0.2% in diet) caused increases in the weight of small intestine. In contrast, no effect of VI (0.26% in diet) on small intestinal weight was observed.

Animals↗
PubMed1998

Palladium(II) complexes with N,N'-dialkyl-1,10-phenanthroline-2,9-dimathanamine: synthesis, characterization and cytotoxic activity.

Five new tetradentate ligands and their corresponding palladium complexes, [Pd(L)]Cl2 (L = N,N'-dimethyl-1,10-phenanthroline-2,9-dimathanamine, N,N'-diethyl-1,10-phenanthroline-2,9-dimathanamine, N,N'-dipropyl-1,10-phenanthroline-2,9-dimathanamine, N,N'-ditert-butyl-1,10-phenanthroline-2,9-dimathanamine, N,N'-dicyclohexyl-1,10-phenanthroline-2,9-dimathanamine) have been synthesized. The ligands and their complexes have been characterized by elemental analysis, IR, and 1H NMR. The complexes have been assayed for antitumor activity in vitro against the mouse leukemia L1210 and the mouse liver carcinoma Bel7402 cell lines. The results showed that the activities of these complexes are significantly dependent on the nature of the alkyl groups on the coordinated amine moieties, and three of these palladium complexes showed lower ID50 values against the two cell lines than cisplatin.

Animals↗
PubMed1998

Effects of tricyclic antidepressants on mechanosensitive pelvic nerve afferent fibers innervating the rat colon.

The aim of this study was to examine the effects of tricyclic antidepressants on responses of mechanosensitive afferent fibers innervating the rat colon. A total of 53 fibers in the decentralized S1 dorsal root were studied. The effects of the non-specific monoamine reuptake inhibitor imipramine (IMI), the noradrenaline reuptake inhibitor desipramine (DES), and the serotonin reuptake inhibitor clomipramine (CLO) were tested on responses of 22 mechanosensitive afferent fibers to noxious colorectal distension (CRD; 80 mmHg). Cumulative doses of 16 mg/kg of IMI, DES and of CLO reduced responses to noxious CRD to a mean 20%, 22% and 46% of control, respectively. The mean inhibitory doses of the three antidepressants did not differ significantly. Inhibitory effects were independent of potential effects on neurotransmitter reuptake: the effects of IMI and DES were not blocked by the adrenoreceptor antagonist phentolamine, and the effects of IMI and CLO were not affected by the serotonin receptor antagonist metergoline. Attenuation of afferent nerve activity was not mimicked by the anticholinergic glycopyrrolate; the cholinesterase inhibitor neostigmine did not attenuate the effect of IMI on responses to noxious CRD. Interestingly, the opioid receptor antagonist naloxone partially reversed the effects of IMI, and the NMDA receptor channel blocker MK-801 enhanced the inhibitory effects of DES and CLO. These results document that responses of mechanosensitive pelvic nerve afferent fibers to noxious CRD are significantly attenuated by tricyclic antidepressants, a peripheral action that may contribute to the beneficial effects of tricyclic antidepressants in treatment of irritable bowel syndrome.

Action Potentials↗
PubMed1998

On the distribution of k-tuple matches for sequence homology: a constant time exact calculation of the variance.

We study the distribution of a statistic useful in calculating the significance of the number of k-tuple matches detected in biological sequence homology algorithms. The statistic is Rn,k, the total number of heads in head runs of length k or more in a sequence of iid Bernoulli trials of length n. Calculation of the mean is straightforward. Poisson approximation formulas have been used for the variance because they are simple and powerful. Unfortunately, when p = P(Head) is large, the Poisson approximation no longer works well. In our application, p is large, say .75, and we have turned instead to direct calculation of the variance. Surprisingly, we are able to show that the variance, which is based on the interactions of O(n2) random variables, can be computed in constant time, independent of the length of the sequence and probability p. This result can be used to calculate the mean and variance of a number of other head run statistics in constant time. Additionally, we show how to extend the result to sequences generated by a stationary Markov process where the variance can be calculated in O(n) time.

Algorithms↗
PubMed1998

Inhibition of p42 and p44 MAP kinase does not alter smooth muscle contraction in swine carotid artery.

Caldesmon inhibits myosin ATPase activity; phosphorylation of caldesmon reverses the inhibition. The caldesmon kinase is believed to be mitogen-activated protein (MAP) kinase. MAP kinases are activated during vascular stimulation, but a cause-and-effect relationship between kinase activity and contraction has not been established. We examined the role of MAP kinase in contraction using PD-098059, an inhibitor of MAP kinase kinase (MEK). MAP kinase activity was assessed using an anti-active MAP kinase antibody and direct measurement of MAP kinase catalyzed phosphorylation of myelin basic protein, MBP-(95-98). MAP kinase phosphorylation, stimulated by histamine (50 microM) or phorbol 12,13-dibutyrate (PDBu, 0.1 microM), was inhibited by PD-098059 (100 microM). PD-098059 did not alter the sensitivity or the maximal level of force in smooth muscle stimulated by histamine or PDBu, nor did PD-098059 affect contraction of beta-escin-permeabilized tissue. Our data suggest that p44 and p42 MAP kinases are not involved in regulation of vascular smooth muscle contraction. These results do not, however, preclude a role for other isoforms of the MAP kinase family.

Animals↗
PubMed1998

Sodium hydrosulfite contractions of smooth muscle are calcium and myosin phosphorylation independent.

In an effort to further understand the processes underlying hypoxic pulmonary vasoconstriction, we examined the mechanism by which sodium hydrosulfite (Na2S2O4), a potent reducing agent and oxygen scavenger, induces smooth muscle contraction. In rat pulmonary arterial strips, sodium hydrosulfite (10 mM) induced contractions that were 65.9 +/- 12.8% of the response to 60 mM KCl (n = 9 segments). Contractions were not inhibited by nisoldipine (5 microM) or by repeated stimulation with caffeine (10 mM), carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (10 microM), or cyclopiazonic acid (10 microM), all of which eliminated responses to contractile agonists. Maximum force generation after exposure to sodium hydrosulfite was 0.123 +/- 0.013 mN in the presence of 1.8 mM calcium and 0.127 +/- 0.015 mN in the absence of calcium. Sodium hydrosulfite contractions in pulmonary arterial segments were not due to the generation of H2O2 and occurred in the presence of chelerythrine (10 microM), which blocked phorbol ester contractions, and solution hyperoxygenation. Similar contractile responses were obtained in rat aortic and tracheal smooth muscles. Finally, contractions occurred in the complete absence of an increase in myosin light chain phosphorylation. Therefore sodium hydrosulfite-induced smooth muscle contraction is not specific to pulmonary arterial smooth muscle, is independent of calcium and myosin light chain phosphorylation, and is not mediated by either hypoxia or protein kinase C.

Alkaloids↗
PubMed1998

Mechanosensitive pelvic nerve afferent fibers innervating the colon of the rat are polymodal in character.

This report describes the chemical and thermal sensitivity of mechanosensitive pelvic nerve afferent fibers innervating the colon of the rat. A total of 51 fibers in the S1 dorsal root, identified by electrical stimulation of the pelvic nerve, were studied. An approximately 7 cm length of descending colon was isolated in situ to permit intracolonic perfusion and distension with Krebs solution. Reproducibility of responses to repetitive colorectal distension (CRD, 40 mmHg, 30 s, every 4 min) was documented. All fibers gave monotonic, incrementing responses to graded CRD (5 to 60 mmHg). Increases (n = 6) or decreases (n = 6) in pH of the perfusate failed to produce any change in resting activity or responses to CRD. Infusion of bile salts increased the resting activity of 6/6 fibers in a concentration-dependent manner, but did not affect the magnitude of responses to CRD. After intracolonic instillation of an inflammatory soup (bradykinin 10(-5) M, PGE2 10(-5) M, serotonin 10(-5) M, histamine 10(-5) M and KCl 10(-3) M), 13/22 fibers exhibited sensitization of responses to CRD. Seventy-three percent of 45 fibers tested responded to intracolonic perfusion of heated Krebs solution. The estimated threshold for response was 45 degreesC and response magnitude increased with the temperature. A smaller proportion (30%) of 37 fibers tested responded to intracolonic perfusion of cold Krebs solution. The estimated threshold for response was 28 degreesC. Of 36 fibers tested, 8 were activated by both heat and cold; typically, fibers activated by heat did not respond to cold. In a sample of 26 fibers tested for response to all three modalities of stimulation, 11 responded to mechanical, chemical and thermal stimuli; the remaining 15 responded to mechanical and either chemical or thermal stimulation. Changes in intracolonic pressure in response to chemical and thermal stimuli were also evaluated. Inflammatory soup and bile salts did not change intracolonic pressure; heat and cold produced a modest decrease and increase in muscle tension, respectively. These results document that mechanosensitive pelvic nerve afferent fibers are also chemosensitive and/or thermosensitive, supporting the notion that visceral mechanoreceptors in general are likely polymodal in character.

Action Potentials↗
PubMed1998

Inhibition of calcium currents in rat colon sensory neurons by K- but not mu- or delta-opioids.

Inhibition of calcium currents in rat colon sensory neurons by kappa- but not mu- or delta-opioids. J. Neurophysiol. 80: 3112-3119, 1998. We previously reported that kappa-, but not mu- or delta-opioid receptor agonists (ORAs) have selective, potentially useful peripheral analgesic effects in visceral pain. To evaluate one potential site and mechanism by which these effects are produced, we studied opioid effects on high-voltage activated (HVA) Ca2+ currents in identified (Di-I) pelvic nerve sensory neurons from the S1 dorsal root ganglion (DRG). Results were compared with opioid effects on cutaneous neurons from L5 or L6 DRG. Di-I-labeled DRG cells were voltage clamped (perforated whole cell patch clamp), and HVA Ca2+ currents were evoked by depolarizing 240-ms test pulses to +10 mV from a holding potential of -60 mV. Neither mu-ORAs (morphine, 10(-6 )M, n = 16; [D-Ala2, N-Me-Phe4, Gly-ol5] enkephalin, 10(-6 )M, n = 12) nor delta-ORAs ([D-Pen2, D-Pen5] enkephalin, 10(-7 )M, n = 16; SNC-80, 10(-7 )M, n = 7) affected HVA Ca2+ currents in colon sensory neurons. In contrast, the kappa-ORAs U50, 488 (10(-6 )M), bremazocine (10(-6)M), and nalBzoH (10(-6 )M) significantly attenuated HVA Ca2+ currents in colon sensory neurons; effects on cutaneous sensory neurons were variable. A nonreceptor selective concentration of naloxone (10(-5 )M) and nor-BNI (10(-6 )M), a selective kappa-opioid receptor antagonist, reversed the inhibitory effect of kappa-ORAs. In the presence of N-, P-, or Q-, but not L-type Ca2+ channel antagonists, the effect of U50,488 on HVA Ca2+ currents was significantly reduced. Pretreatment with pertussis toxin (PTX) prevented the inhibition by U50,488. These results suggest that kappa-opioid receptors are coupled to multiple HVA Ca2+ channels in colon sensory neurons by a PTX-sensitive G protein pathway. We conclude that inhibition of Ca2+ channel function likely contributes in part to the peripheral analgesic action of kappa-ORAs in visceral nociception.

Animals↗
PubMed1998

[Preliminary study on Chlamydia pneumoniae pneumonia].

In order to know the incidence of Chlamydia pneumoniae (strain TWAR) pneumonia and its clinical features, 93 patients with pneumonia and 93 matched patients with non-respiratory diseases were studied. TWAR antibodies (IgG and IgM) were detected by microimmunofluorescence (MIF) test. The results showed that 19.4% (18 cases) patients with pneumonia were TWAR pneumonia, in which 10 cases accompanied by bacteria infection and 7 cases being simple TWAR pneumonia. There were no significant differences in clinical features between TWAR pneumonia and non-TWAR pneumonia, except dry and moist rales. These data showed that the occurrence percentage of TWAR pneumonia in patients with lung cancer was higher than that in patients with the other respiratory diseases. This study suggests that there are TWAR pneumonia in China.

Adolescent↗
PubMed1998

[Application of comparative genomic hybridization to hyperdiploid acute lymphoblastic leukemia].

OBJECTIVE: To evaluate the implication of comparative genomic hybridization (CGH) in leukemia study. METHODS: Genomic abnormalities in 14 ALL patients were assayed by CGH, and the results were compared with those of conventional karyotype analysis. RESULTS AND CONCLUSION: Regional and/or whole chromosome over-representation was found to be more frequent than under-representation (43 gains versus 6 losses), the most common gains involved being chromosomes 21 and X. Comparison between the results of CGH and conventional R-banding analysis showed that: 1. In 2 cases with trisomy, both the methods gave identical results. 2. In 8 cases, both the results were consistent excepting for minor discrepancies. 3. In 3 cases, including 2 each with triploidy and tetraploidy respectively, and one with chimeric karyotype of normal/+22, the results from the two methods were discrepant.

Adolescent↗
PubMed1998

[A clinicopathological analysis of primitive neuroectodermal tumors of the CNS].

OBJECTIVE: To investigate the difference between cerebellar medulloblastoma (MB) and primary cerebral small cell tumor in histogenesis, morphologic features and biological behavior. METHODS: 210 cases of MB and 9 cases of small cell tumor of cerebrum were observed with histologic and immunohistochemical techniques. RESULTS: Both tumors were composed of primitive cells with focal evidence of glial and/or neuronal differentiation. In 63.2% of MB and five-eighths of small cell tumor of cerebrum coexpressed GFAP and Syn. Both types of tumors were highly malignant. The overall 1 year survival rates were 34.63% and 25.65% respectively. The survival rate was lower for patients with high proliferative index, with necrosis or without receiving radiation therapy. CONCLUSION: MB is similar to other small cell tumors of CNS in morphological features, specific marker expression and biological behavior. These tumors can be classified as primitive neuro-ectodermal tumors (PNET).

Adolescent↗
PubMed1998

[Studies on complex chromosomal translocation and their relevance to clinical prognosis in acute promyelocytic leukemia].

OBJECTIVE: To study the relationship between the complex chromosome translocation in acute promyelocytic leukemia(APL, M3) and clinical therapy and prognosis. METHODS: Chromosome translocation and PML-RAR fusion transcript in three APL patients were studied by using karyotypic analysis, fluorescence in situ hybridization and reverse transcriptase/polymerase chain reaction. RESULTS: The findings revealed that all these cases had PML/RAR A gene rearrangement. Apart from the chromosomes 15 and 17 involved in the translocation, other multiple chromosomes including 5, 11, 16, 22 were also implicated in complex translocations, which to some extent seemed to be related with clinical prognosis. CONCLUSION: This study provides additional information for monitoring clinical therapy and prognostic evaluation.

Adult↗