Biomedical subjects

R Xu

Publications and source records attributed to R Xu.

At least 73 records · Page 4Linked to original sources

PubMed2001

[The curative effect of livostin spray on treating allergic rhinitis of children].

OBJECTIVE: To observe the effect of Livostin spray on children's allergic rhinitis and to search the mechanism of treating allergic rhinitis. METHOD: 113 patients were treated with Livostin spray (Livostin group) or normal saline spray (control group). RESULT: The total efficiency of Livostin group in treating allergic rhinitis is above 95.1% and that of the control group is 25.0%. Initial time of starting effect of Livostin (72.1%) is in 1 minute, and that of the control group (mostly 23.1%) is in 3 minutes. The keeping curative effect time of Livostin spray is mostly (72.1%) above 5 hours and that of the control group is mostly (30.8%) in 3 hours. After 2 weeks, the eosinophilic granulocyte number in nose's secretion of Livostin group is obviously reduced (P < 0.05). CONCLUSION: Livostin is better than control group in relieving symptoms, keeping curative effect and safety, so Livostin is one kind of effective drug in treating children's allergic rhinitis.

Administration, Intranasal↗

PubMed2001

[Pharyngeal passage tube treatment for obstructive apnea syndrome].

OBJECTIVE: To investigate the therapeutical effect of pharyngeal passage tube for OSAS. METHODS: Fifty-seven patients were treated during May 1995 to August 1999. All patients were examined by GKD-405 A polysomnography for apnea index (AI), hypnea index (HI), AHI (AI + HI) at cetera 7 items index before and after pharyngeal passage tube treatment. RESULTS: After treatment, the longest time of apnea shortened from (54.82 +/- 20.83) s to (25.74 +/- 9.50) s, the AHI lessened from 70.82 +/- 18.06 to 30.00 +/- 10.10, the oxygen desaturation increased from (62.36 +/- 11.53)% to (78.68 +/- 12.09)%. After treatment, the recorded parameters showed obvious therapeutical effect (P < 0.05-0.001, t values is from 2.20 to 15.29, the snore loudness of all patients dropped from (84.32 +/- 18.51) dB to (32.64 +/- 10.16) dB. The therapeutical successful rate was 87.72%. The long-term use rate (over 6 months) was 72.73%. CONCLUSION: The pharyngeal passage tube has obvious effect for patients suffering from severe OSAS. It is recommended for the treatment of OSAS as a conservative method.

Adult↗

PubMed2001

[Expressions of vascular endothelial growth factor and basic fibroblast growth factor in nasal polyp and its role].

OBJECTIVE: To evaluate the role of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor(bFGF) in the pathophysiology of nasal polyp. METHODS: Thirty-nine patients with nasal polyp were divided into two groups: group A(representing type 1 and type 2 phase 1-2) and group B (representing type 2 phase 3 and type 3). The expression of VEGF and and bFGF in both groups were studied with immunohistochemical method. RESULTS: VEGF and bFGF were not detected in norms. The detection rates of VEGF and bFGF were 59%, 41%, and 71%, 80% in group A and group B respectively. The positive rate and the number of positive cells were higher significantly in group B than that in group A. VEGF and bFGF were located mainly in the inflammatory cells and epithelial cells around the basilar membrane and inflammatory cells and endothelial cells around the vessel. CONCLUSIONS: The overexpression of VEGF and bFGF in nasal polyp may contribute to the growth of vessels, accumulation of inflammatory cells, as a result, to enhance the development of nasal polyposis. This phenomenon maybe an important histological mark distinguishing ordinary polyp from polyposis.

Adolescent↗

PubMed2001

[Raman spectra for YVO4 and Nd:YVO4 crystals].

In this paper, the measured Raman spectra of YVO4 and Nd: YVO4 crystals were reported. These results give a clear information on the phonon energy spectra, these are several discrete phonons in low energy region, then nothing shows up in a large space from 500-800 cm-1 and main portion of phonon spectra is distributed in the region of 800-900 cm-1. Based on the group theory, the symmetries for Raman lines can be deduced, and they are almost due to the vibration of VO(4)3- ion. The effect of uneven distribution for phonon spectra on the optical transition and laser performance are discussed. The restraint action of doped ion on the high energy phonon is found.

Crystallization↗

PubMed2001

[Study on the expression of human acute myeloid leukemia retrovirus gene].

OBJECTIVE: To explore the potentiality of retroviral etiology in human acute myeloid leukemia (AML). METHODS: The expression of retrovirus clone 6 # 11 in leukemic cells from 19 AML patients and peripheral blood mononuclear cells (PBMNCs) from 20 controls was studied by Northern blot and reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: Northern blot revealed the positive bands of 9.4 kb and 4.5 kb in 18 of 19 AML patients, and RT-PCR a 790 bp product in 11 of 14 AML patients. CONCLUSION: There was a specific expression of acute myeloid leukemia associated retrovirus in AML patients.

Adolescent↗

PubMed2001

[Effects of octreotide on implanted liver tumor after partial hepatectomy in rats].

OBJECTIVES: To investigate the effects of octreotide(OCT) on experimental live tumor after partial hepatectomy (PH) in rats and explore its intrinsic mechanism. METHODS: Sixty-four male rats were randomly divided into four groups and operated on with laparotomy. Walker-256 tumor was implanted in all the four groups. Group A served as the control, and groups B, C and D received left lobe PH. Octreotide at a dose of 50 microg/kg was intraperitoneally (i.p.) administered twice a day in groups C and D (OCT). The time of the first administration was at the 12th hour after PH in group C and the 72nd hour after PH in group D. The rats in groups A and B received a similar volume of normal saline (NS). RESULTS: Group A showed a significant reduction of implanted liver tumor volume at the 7th day versus group B (P < 0.01). Groups C and D showed a significant reduction of tumor volume at the 7th and 15th day versus group B (P < 0.01). The tumor cell apoptotic rate was significantly higher in groups C and D than in groups A and B at the 7th and 15th day (P < 0.01). CONCLUSION: The growth of experimental liver tumor is enhanced after PH bat can be inhibited by OCT.

Animals↗

PubMed2000

Proportional hazards model with random effects.

We propose a general proportional hazards model with random effects for handling clustered survival data. This generalizes the usual frailty model by allowing a multivariate random effect with arbitrary design matrix in the log relative risk, in a way similar to the modelling of random effects in linear, generalized linear and non-linear mixed models. The distribution of the random effects is generally assumed to be multivariate normal, but other (preferably symmetrical) distributions are also possible. Maximum likelihood estimates of the regression parameters, the variance components and the baseline hazard function are obtained via the EM algorithm. The E-step of the algorithm involves computation of the conditional expectations of functions of the random effects, for which we use Markov chain Monte Carlo (MCMC) methods. Approximate variances of the estimates are computed by Louis' formula, and posterior expectations and variances of the individual random effects can be obtained as a by-product of the estimation. The inference procedure is exemplified on two data sets.

Algorithms↗

PubMed2000

Dopamine D2 long receptor-deficient mice display alterations in striatum-dependent functions.

The dopamine D2 receptor (D2) system has been implicated in several neurological and psychiatric disorders, such as schizophrenia and Parkinson's disease. There are two isoforms of the D2 receptor: the long form (D2L) and the short form (D2S). The two isoforms are generated by alternative splicing of the same gene and differ only by 29 amino acids in their protein structures. Little is known about the distinct functions of either D2 isoform, primarily because selective pharmacological agents are not available. We generated D2L receptor-deficient (D2L-/-) mice by making a subtle mutation in the D2 gene. D2L-/- mice (which still express functional D2S) displayed reduced levels of locomotion and rearing behavior. Interestingly, haloperidol produced significantly less catalepsy and inhibition of locomotor activity in D2L-/- mice. These findings suggest that D2L and D2S may contribute differentially to the regulation of certain motor functions and to the induction of the extrapyramidal side effects associated with the use of typical antipsychotic drugs (e.g., haloperidol). Quinpirole induced a similar initial suppression of locomotor activity in both D2L-/- and wild-type mice. In addition, the D2S receptor in the mutant mice functioned approximately equally well as did D2L as an impulse-modulating autoreceptor. This suggests that the functions of these two isoforms are not dependent on the formation of receptor heterodimers. Our findings may provide novel information for potentially developing improved antipsychotic drugs.

Animals↗

PubMed2000

c-Jun promotes neurite outgrowth and survival in PC12 cells.

We investigated the function of c-Jun in PC12 cells by transfecting them with a plasmid containing a c-Jun cDNA transcription cassette. Transfected cells expressed high levels of c-Jun mRNA and protein and demonstrated an increase in both AP-1 DNA binding and gene activation. The c-Jun over-expressing cells showed marked neurite outgrowth but no evidence of spontaneous cell death. In fact, c-Jun over-expressing cells were more resistant to okadaic acid-induced apoptosis. The process outgrowth was not indicative of a full neuronal differentiation response as the transfected PC12 cells did not display action potentials when examined with whole-cell patch-clamping. The phosphorylation of c-Jun on serine 73 appears to be important for this neurite sprouting effect as mutagenesis at this site reduced sprouting whereas a serine 63 mutant tended to increase sprouting. Thus, in PC12 cells c-Jun expression does not induce apoptosis, but rather functions as a neurite outgrowth and neuronal survival signal.

Action Potentials↗

PubMed2000

Correlation of a unique 220-kDa protein with vitamin D sensitivity in glioma cells.

We have investigated the antitumor and apoptotic effects of 1, 25-dihydroxyvitamin D(3) (VD(3)) in glioma cell lines and in primary cultures derived from surgical specimens from patients. Our results showed that certain glioma cells underwent apoptosis, whereas others were resistant. In an attempt to search for parameters that dictate VD(3) sensitivity, we discovered a unique 220-kDa protein in glioma cells that were sensitive to VD(3). This protein was not a classical vitamin D receptor (VDR), but was recognized by two different anti-VDR monoclonal antibodies. Furthermore, the level of the 220-kDa protein was inversely correlated with the IC(50) of VD(3) in these glioma cells. This 220-kDa protein was also present in frozen brain tumor samples, and the level of expression appeared to correlate with their corresponding primary cultures. Thus, our findings suggest that this 220-kDa protein may play an important role in determining VD(3) sensitivity in malignant glioma.

Apoptosis↗

PubMed2000

Kringle 1 of human hepatocyte growth factor inhibits bovine aortic endothelial cell proliferation stimulated by basic fibroblast growth factor and causes cell apoptosis.

Hepatocyte growth factor (HGF), also known as scatter factor, is a mesenchymal or stromal-derived mediator with angiogenic activity. There are four kringle domains in its amino terminus. They display considerable sequence similarity with those of angiostatin, an angiogenesis inhibitor. We now describe that the recombinant kringle1 of HGF (HGFK1) inhibits bovine aortic endothelial (BAE) cell proliferation stimulated by basic fibroblast growth factor in a dose-dependent manner, with an ED(50) of approximately 0.7 microg/ml, while ED(50) of angiostatin is 3 microg/ml. Treatment of BAE cell with HGFK1 caused cell apoptosis. This report thus constitutes the first demonstration that kringle1 of HGF is a selective inhibitor for BAE cell proliferation stimulated by bFGF.

Angiogenesis Inhibitors↗

PubMed2000

Cloning and characterization of a Saccharomyces cerevisiae alkaline ceramidase with specificity for dihydroceramide.

In a previous study, we reported that the Saccharomyces cerevisiae gene YPC1 encodes an alkaline ceramidase with a dual activity, catalyzing both hydrolysis and synthesis of yeast ceramide (Mao, C., Xu, R., Bielawska, A., and Obeid, L. M. (2000) J. Biol. Chem. 275, 6876-6884). In this study, we have identified a YPC1 homologue in S. cerevisiae that also encodes an alkaline ceramidase. We show that these two ceramidases have different substrate specificity, such that YPC1p preferentially hydrolyzes phytoceramide, whereas the new ceramidase YDC1p hydrolyzes dihydroceramide preferentially and phytoceramide only slightly. Neither enzyme hydrolyzes unsaturated mammalian-type ceramide. In contrast to YPC1p, YDC1p had only minor in vitro reverse activity of catalyzing dihydroceramide formation from a free fatty acid and dihydrosphingosine and no activity with phytosphingosine. Overexpression of YDC1p had no reverse activity in non-stressed yeast cells, but like YPC1p suppressed the inhibition of growth by fumonisin B1 albeit more modestly. Deletion of YDC1 and YPC1 or both did not apparently affect growth, suggesting neither gene is essential. However, the Deltaydc1 deletion mutant but not the Deltaypc1 deletion mutant was sensitive to heat stress, indicating a role for dihydroceramide but not phytoceramide in heat stress responses, and suggesting that the two enzymes have distinct physiological functions.

Amidohydrolases↗

PubMed2000

Immunosuppressive activity of the Chinese medicinal plant Tripterygium wilfordii. I. Prolongation of rat cardiac and renal allograft survival by the PG27 extract and immunosuppressive synergy in combination therapy with cyclosporine.

BACKGROUND: PG27 is an immunosuppressive fraction purified from an extract of a Chinese medicinal plant, Tripterygium wilfordii. We tested PG27 in rat cardiac and renal allotransplantation, and we examined the immunosuppressive interaction with cyclosporine (CsA). METHODS: Brown Norway (BN) rat heart or kidney allografts were transplanted into the abdomen of Lewis rats, which were treated by the intraperitoneal or oral route with PG27, CsA, or both. RESULTS: PG27 administered intraperitoneally to Lewis recipients for 16 days at 10-30 mg/kg/day significantly increased the median survival time of BN heart allografts from 7 to 18-22 days. Oral administration was effective, with cardiac allograft survival prolonged to > 100 days with 52 days of treatment. PG27 at 20-30 mg/kg/day significantly extended the median survival time of BN kidney allograft recipients from 9 to 36.5-77 days, and 30 mg/kg/day for 52 days extended survival beyond 200 days. PG27 combined with CsA significantly enhanced heart and kidney allograft survival, even at doses of CsA ineffective when administered alone. The addition of 5 or 10 mg/kg/day PG27 reduced by 50-75% the CsA dose needed for 100% kidney allograft survival. The combination index was less than 1.0, indicating synergy of PG27 with CsA in prolonging cardiac and renal allograft survival. Furthermore, the PG27/CsA combination exerted a positive influence on renal allograft function. PG490 (triptolide, a constituent of PG27) and PG490-88 (a semisynthetic derivative of PG490) suppressed rejection of cardiac and renal allografts. CONCLUSIONS: The PG27 herbal extract demonstrated immunosuppressive activity by prolonging heart and kidney allograft survival, displaying synergy in the immunosuppressive interaction with CsA, and improving renal allograft function in combination with CsA. PG490 and PG490-88 compounds were also effective.

Animals↗

PubMed2000

Immunosuppressive activity of the Chinese medicinal plant Tripterygium wilfordii. II. Prolongation of hamster-to-rat cardiac xenograft survival by combination therapy with the PG27 extract and cyclosporine.

BACKGROUND: PG27 is an immunosuppressive fraction purified from an extract of a Chinese medicinal plant Tripterygium wilfordii, which we investigated alone and in combination with cyclosporine (CsA) in a concordant, hamster-to-rat cardiac xenotransplantation model. METHODS: Golden Syrian hamster hearts were heterotopically transplanted into the abdomen of Lewis rat recipients, which were treated intraperitoneally or orally with PG27, CsA, or both. RESULTS: Combination therapy with 30 mg/kg(day of PG27 and CsA at 10 mg/kg/day successfully suppressed acute hamster-to-rat cardiac xenograft rejection. Treatment with PG27 or CsA alone was ineffective. Among several effective combinations, the best regimen involved PG27 at 30 mg/kg/day and CsA at 5 mg/ kg/day from days 8 to 35 and then CsA at 5 mg/kg/day from days 36 to 100, which produced 100% survival beyond 100 days. CsA suppressed the heterospecific lymphocytotoxic antibody response and inhibited IgG but not IgM xenoantibody production (which led to xenograft rejection), whereas PG27 alone did not prevent antibody production. The PG27/CsA combination blocked the lymphocytotoxic antibody response and IgG and IgM xenoantibody production induced by cardiac xenotransplantation. CONCLUSIONS: PG27 combined with CsA substantially prolonged hamster-to-rat cardiac xenograft survival, as well as completely inhibiting xenoantibody production.

Animals↗

PubMed2000

Cloning of an alkaline ceramidase from Saccharomyces cerevisiae. An enzyme with reverse (CoA-independent) ceramide synthase activity.

Ceramide is not only a core intermediate of sphingolipids but also an important modulator of many cellular events including apoptosis, cell cycle arrest, senescence, differentiation, and stress responses. Its turnover may be tightly regulated. However, little is known about the regulation of its metabolism because most enzymes responsible for its synthesis and breakdown have yet to be cloned. Here we report the cloning and characterization of the yeast gene YPC1 (YBR183w) by screening Saccharomyces cerevisiae genes whose overexpression bestows resistance to fumonisin B1. We demonstrate that the yeast gene YPC1 encodes an alkaline ceramidase activity responsible for the breakdown of dihydroceramide and phytoceramide but not unsaturated ceramide. YPC1 ceramidase activity was confirmed by in vitro studies using an Escherichia coli expression system. Importantly, YPC1p also has reverse activity, catalyzing synthesis of phytoceramide from palmitic acid and phytosphingosine. This ceramide synthase activity is CoA-independent and is resistant to fumonisin B1, thus explaining why YPC1 was cloned as a fumonisin B1-resistant gene.

Amidohydrolases↗

PubMed2000

An oral vaccine against NMDAR1 with efficacy in experimental stroke and epilepsy.

The brain is generally considered immunoprivileged, although increasing examples of immunological responses to brain antigens, neuronal expression of major histocompatibility class I genes, and neurological autoimmunity have been recognized. An adeno-associated virus (AAV) vaccine generated autoantibodies that targeted a specific brain protein, the NR1 subunit of the N-methyl-D-aspartate (NMDA) receptor. After peroral administration of the AAV vaccine, transgene expression persisted for at least 5 months and was associated with a robust humoral response in the absence of a significant cell-mediated response. This single-dose vaccine was associated with strong anti-epileptic and neuroprotective activity in rats for both a kainate-induced seizure model and also a middle cerebral artery occlusion stroke model at 1 to 5 months following vaccination. Thus, a vaccination strategy targeting brain proteins is feasible and may have therapeutic potential for neurological disorders.

Administration, Oral↗

PubMed2000

Internal architecture of the sacrum in the elderly. An anatomic and radiographic study.

STUDY DESIGN: A description of the internal architecture of the sacrum, including its trabecular arrangement, cortical thickness, and overall bone density. OBJECTIVES: To determine the strong and weak areas in the sacrum to understand more clearly the sacral structure and its clinical implications. METHODS: First, seven cadaveric sacral specimens were sectioned in different planes. Horizontal sections were performed at the upper S1, middle S1, S2, S3, and S4. Sagittal sections were made through the median sacral crest, the sacral foramina, and medial to the articular surface. A coronal section through the whole length of a sacral specimen was produced. All sections were studied radiographically, and the trabecular pattern was analyzed. In the second part of the study, axial computed tomography scans of 40 dry sacrum specimens were analyzed by using the National Institutes of Health Image 1.61 program. The cortical thickness and bone density were determined. RESULTS: In the upper sacrum, three distinctive distributions of bony trabeculae were noted, one extending from the center of the sacral body anterolaterally, and the other two extending from the pedicle toward the auricular surface. A condensation zone was observed at the intersection of these trabeculae and was located at the anterior cortex of the foraminal zone. The junction between S2 and S3 represented a weak area with abrupt disappearance of the condensation zone. Analysis of the bone density of the sacrum using the plot analysis demonstrated that, at S1 and S2, the anterior cortex of the foraminal zone (condensation zone) is the most compact part of the sacrum. CONCLUSION: These results suggest that the strongest part of the sacrum is the anterior cortex above the foramina in S1 and S2. The weakest point of the sacrum was found to lie at the level of the junction of S2 and S3.

Aged↗

PubMed2000

The optimal transarticular c1-2 screw length and the location of the hypoglossal nerve.

BACKGROUND: Injury to the hypoglossal nerve is a complication associated with transarticular C1-2 screw placement. This complication can be caused by a misdirected or too long screw. Little is known about the optimal screw length and its relationship to the hypoglossal nerve. METHODS: Twenty cervical spine specimens were used to study the optimal length of the transarticular C1-2 screw. Using the Magerl technique, a 3.0 mm drill bit was inserted into the C2 lateral mass, passing through the C1-2 facet joint and penetrating the upper portion of the ventral cortex of the lateral mass of the atlas. After drilling, the hole length was measured between the dorsal cortex of the C2 inferior articular process and the ventral cortex of the C1 lateral mass. In addition, six sagittal-sectioned cadavers were carefully dissected to observe the location of the hypoglossal nerve in the anterior aspect of the atlantoaxial region. RESULTS: The results of the measurements showed that the mean optimal screw path length for all specimens was 38.1 +/- 2.2 mm with a range of 34-43 mm. There was no significant difference between sexes in the screw path length (p 0.05). The hypoglossal nerve lies vertically in front of the lateral portion of the C1 lateral mass and the C1-2 facet joint. The area where the hypoglossal nerve lies is approximately 2-3 mm lateral to the middle of the anterior aspect of the C1 lateral mass. CONCLUSIONS: This study suggests that the mean optimal transarticular C1-2 screw length may be 38 mm; however, the determination of the accurate optimal C1-2 screw length should be made on an individual basis. Risk to the hypoglossal nerve can be eliminated if Magerl's technique is performed exactly.

Aged↗