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Biomedical subjects

X Feng

Publications and source records attributed to X Feng.

At least 145 records · Page 8Linked to original sources
PubMed1998

[Report of 18 cases lymphoblastic lymphoma].

OBJECTIVE: To identify the clinical, pathological, and immunological characteristics of lymphoblastic lymphoma (LBL). METHODS: The relation of clinical features, cellular morphology and immuno-phenotypes to the treatment outcome and prognosis was analyzed in 18 LBL patients. RESULTS: The patients were 15 males and 3 females with a median age of 27 years. Fourteen cases showed bone marrow infiltration, 10 lymphoma leukemia and 9 mediastinal tumor. Fifteen cases were of convoluted cell type expressed T cell marker, three patients were of B-cell type and all achieved complete remission. The 5 year survival rate of the 18 cases was 11.2% with a median survival duration of 10.1 months. CONCLUSION: LBL was found predominantly in male with a younger onset age, and was characterized by involvement of bone marrow and mediastina. The majority of LBL patients were of convoluted cell type expressed T cell marker. The patients showed poor response to therapy, while B-cell type showed a better prognosis than T-cell type.

Adolescent↗
PubMed1998

[Synthesis and bioaction of 2-alkyl-4(1H)-quinolone].

Five quinolone alkaloids (IVa, Va, c, d, g) including two new compounds (IVa, Vc) from Evodia rutaecarpa and nine analogs are synthesized in good yield by using acid-catalyzed condensation of a series of 3-oxoalkkanoic acid esters with aniline and further methylized with methyl iodide. The other analogue Vh is prepared through the reaction of lithium enolate methyl ketone with N-methylisatoic anhydride. Eight compounds (IVa, d, f; Vb, c, d, f, h) were synthesized for the first time. Pharmacological studies showed that these compounds have vasoconstriction inhibiting and antiulcer effects. Compound IVb also has cytotoxic effect.

Alkaloids↗
PubMed1998

[Studies on synthesis and bioactivity of 2-alkenyl-4(1H)-quinolone].

Three 2-alkenyl-4(1H)-quinolone compounds(I-III) were synthesized by two methods. III is a new compound from Evodia rutaecarpa and was synthesized through the reaction of the aldehyde intermediate(5) with Wittig reagent. The other two compounds were synthesized for the first time. These compounds showed vasodilating and antibacteria effects in pharmacological tests.

Anti-Infective Agents↗
PubMed1998

[Effect of excitatoxicity on Ca2+/CaM PK II activity in rat hippocampal slices].

The relation between Ca2+/CaM PK II activity and excitatoxicity was studied in an in vitro model of rat hippocampal slices. The slices were exposed to 50-200 mumol.L-1 glutamate or 25-100 mumol.L-1 NMDA and glucose-free Krebs buffer for 30 min after being recovered to normal conditions by 2 hours of incubation with standard Krebs buffer. The results showed that inhibition of Ca2+/CaM PK II activity in rat hippocampal slices was induced by exogenous EAA (glutamate or NMDA), and Ca2+/CaM PK II activity values decreased to 50.1% and 44.7% of control at 200 mumol.L-1 glutamate and 100 mumol.L-1 NMDA, respectively; MK801, but not DNQX, antagonized EAA-induced inhibition of Ca2+/CaM PK II activity. When the slices were pretreated with MK801 prior to exposure to 200 mumol.L-1 glutamate or 100 mumol.L-1 NMDA, the Ca2+/Cam PK II activity values were 91.5% and 96.7%, respectively. The changes of extracellular Ca2+ or Mg2+ concentration influenced Ca2+/CaM PK II activity of the slices exposed to exogenous glutamate; Ca2+/CaM PK II activity values in the presence of extracellular Ca2+ was lower than that in the absence of extracellular Ca2+, and it changed from 50.1% of control (presence of Ca2+) to 64% of control (absence of Ca2+) at 200 mumol.L-1 glutamate, but Ca2+/CaM PK II activity values in the presence of extracellular Mg2+ was higher than that in the absence of extracellular Mg2+, and it changed from 50.1% of control(presence of Mg2+) to 36.6% of control (absence of Mg2+) at 200 mumol.L-1 glutamate. The results suggest that NMDA receptor may be involved in excitotoxicity-induced inhibition of Ca2+/CaM PK II activity.

Animals↗
PubMed1998

[Study on detection of malaria parasite DNA by PCR-ELISA].

AIM: To present a new malaria diagnostic method based on detection of malaria parasite DNA by PCR-ELISA. METHODS: According to the conserved sequence of Plasmodium SSUrRNA genes reported, a pair of primers in which one primer was biotinylated and another was unbiotinylated, suitable for DNA amplification of both falciparum and vivax malaria parasites were designed and synthesized. After denaturation and washing, the incorporated biotinylated product with avidin coated on plates previously was hybridized with the fluorescein-labelled oligonucleotide probes specific for Plasmodium falciparum or Plasmodium vivax. The color developed after adding POD conjugated with antibody to fluorescein and substrate can be semi-quantitated spectrophotometrically. RESULTS: The thresholds of parasite density for the detection of Plasmodium falciparum and Plasmodium vivax by this test were shown to be as low as 4 and 10 parasites per microliter of blood, respectively and no cross reaction was seen in the detection of falciparum and vivax malaria parasites. CONCLUSION: With promising sensitivity and specificity, this test can be used in malaria survey.

Animals↗
PubMed1998

[The distribution of nitric oxide synthetase in Vcx and its relation with the expression of FOS induced by teeth movement in rats].

It was studied the central role of nitric oxide(NO) during experimental teeth movement and the relation between nitric oxide synthetase (NOS) positive neurons and FOS like immunoreactivity (FLN) with the NADPH-diaphorase histochemistry and immunocytochemical reaction method. Results indicated that NOS positive neurons and FLN showed typical distribution in Vcx and there was some overlap between them. It suggests that NO is involved in the central modulation of the stimulating message of teeth movement, and which further explains the central modulation mechanism of experimental teeth movement in rats.

Animals↗
PubMed1998

[Analysis of constituents of essential oil from Anemone altaica Fisch. ex C. A. Mey].

OBJECTIVE: Analyzing the constituents of the essential oil from Waichangpu(dried rhizome of Anemone altaica, often mistakenly called "Jiujiechangpu"). METHOD: Separating and identifying the constituents by GC-MS. RESULT: Twenty-two compounds from the essential oil from Waichangpu were separated and identified, the main ones being cedrenol(23.69%), beta-eudesmol(8.49%), elemol(2.80%), hexadecanoic acid(4.77%) and 9, 12-octadecadienoic acid(14.93%). CONCLUSION: The essential oil content is very low in Waichangpu, and the oil structure of Waichangpu is obviously different from that of Shichangpu(dried rhizome of Acorus tatarinowii, whose another name is Jiujiechangpu). The present study provides a chemical basis to support the view that Waichangpu should not be confused with Shichangpu as a medicinal herb.

Anemone↗
PubMed1998

[Biodegradation and biocompatibility of a chitosan film].

The biodegradability and biocompatibility of a chitosan film were investigated in mice. The results showed that chitosan films had a mild inflammatory reaction in the early days of grafting, and after 16 weeks the inflammation basically subsided. Chitosan films were easily biodegraded. Chitosan is a novel natural absorbable medical film material and has a good developmental prospect.

Animals↗
PubMed1998

[Precollagen III in the vitreous of eyes with proliferative vitreoretinopathy].

PURPOSE: To detect precollagen III (PC III) levels in serum and vitreous samples from patients with proliferative vitreoretinopathy (PVR). METHODS: PC III levels were measured by radioimmunoassay in 5 cadaveric vitreous samples from normal subjects, 20 normal human serum samples, 29 vitreous and serum samples from patients with rhegmatogenous retinal detachment complicated with PVR. The relationship between PC III levels and PVR history, surgery, epiretinal membrane, severity of PVR were analyzed with Logistic regression analysis. RESULTS: The mean PC III levels in serum samples of PVR patients and control subjects were 83.76 +/- 18.52 and 85.02 +/- 17.50 micrograms/L respectively (P > 0.05). PC III was not detected (< 40 micrograms/L) in the cadaveric vitreous. In vitreous aspirates from 29 eyes with PVR, it was not detected in 12 eyes, but higher than 40 micrograms/L in 17 eyes with the mean level of 268.69 +/- 176.07 micrograms/L. (P < 0.05) The high levels correlated with duration and severity of PVR. As onset time and PVR grade increasing, the probability of PC III concentration higher than 40 micrograms/L was 5.2655 and 2.7978 times the concentration lower than 40 micrograms/L respectively. CONCLUSION: PC III can be detected in vitreous aspirates from PVR eyes. The PC III levels in the vitreous was an event of local responses and were correlated with severity and history of PVR. This suggests that PC III and collagen III be involved in the development of PVR.

Adolescent↗
PubMed1998

[Burner head with high sensitivity in atomic absorption spectroscopy].

This paper presents a burner head with gas-sample separate entrance and double access, which is used for atomic absorption spectroscopy. According to comparison and detection, the device can improve sensitivity by a factor of 1 to 5. In the meantime it has properties of high stability and resistance to interference.

English Abstract↗
PubMed1997

The conformation of an inhibitor bound to the gastric proton pump.

Substituted imidazo[1,2-a]pyridines are pharmaceutically important small molecule inhibitors of the gastric H+/K+-ATPase, the membrane-bound therapeutic target for peptic ulcer disease. A non-perturbing analytical technique, rotational resonance NMR spectroscopy, was used to measure a precise (to +/-0.2 A) distance between atomic sites in a substituted imidazo[1,2-a]pyridine, TMPIP, bound to H+/K+-ATPase at its high-affinity site in the intact, native membrane. The structural analysis of the enzyme-inhibitor complex revealed that the flexible moiety of TMPIP adopts a 'syn-type' conformation at its site of action. Hence, the conformation of an inhibitor has been resolved directly under near-physiological conditions, providing a sound experimental basis for rational design of many active compounds of pharmaceutical interest. Chemically restraining the flexible moiety of compounds like TMPIP in the syn-type binding conformation was found to increase activity by over 2 orders of magnitude. Such information is normally only available after extensive synthesis of related compounds and multiple screening approaches.

H(+)-K(+)-Exchanging ATPase↗
PubMed1997

Structural and antigenic identification of the ORF12 protein (alpha TIF) of equine herpesvirus 1.

The equine herpesvirus 1 (EHV-1) homolog of the herpes simplex virus type 1 (HSV-1) tegument phosphoprotein, alpha TIF (Vmw65; VP16), was identified previously as the product of open reading frame 12 (ORF12) and shown to transactivate immediate early (IE) gene promoters. However, a specific virion protein corresponding to the ORF12 product has not been identified definitively. In the present study the ORF12 protein, designated ETIF, was identified as a 60-kDa virion component on the basis of protein fingerprint analyses in which the limited proteolysis profiles of the major 60-kDa in vitro transcription/ translation product of an ORF12 expression vector (pT7-12) were compared to those of purified virion proteins of similar size. ETIF was localized to the viral tegument in Western blot assays of EHV-1 virions and subvirion fractions using polyclonal antiserum and monoclonal antibodies generated against a glutathione-S-transferase-ETIF fusion protein. Northern and Western blot analyses of EHV-1-infected cell lysates prepared under various metabolic blocks indicated that ORF12 is expressed as a late gene, and cross reaction of polyclonal anti-GST-ETIF with a 63.5-kDa HSV-1 protein species suggested that ETIF and HSV-1 alpha TIF are antigenically related. Last, DNA band shift assays used to assess ETIF-specific complex formation indicated that ETIF participates in an infected cell protein complex with the EHV-1 IE promoter TAATGARAT motif.

Animals↗
PubMed1997

Suprabasal expression of a dominant-negative RXR alpha mutant in transgenic mouse epidermis impairs regulation of gene transcription and basal keratinocyte proliferation by RAR-selective retinoids.

To determine whether 9-cis retinoic acid receptors (RXRs) regulate the biological activity of all-trans retinoic acid (tRA) and its receptors (RARs) in skin, we have targeted a dominant-negative RXR alpha (dnRXR alpha) lacking transactivation function AF-2 to differentiated suprabasal keratinocytes in the epidermis of transgenic mice. Driven by the suprabasal-specific keratin-10 gene promoter, expression of dnRXR alpha severely reduced the ability of RAR-selective ligands tRA and CD367 to induce epidermal mRNA levels of the CRABPII, CRBPI, and CRBPII genes, which contain RA-responsive elements (RAREs) DR1 and/or DR2. It also reduced gene-specific, synergistic induction of CRBPI mRNA by a combination of CD367 and RXR-selective SR11237. Like endogenous RXR alpha, dnRXR alpha in epidermal nuclear extracts from the transgenic mice competitively formed heterodimers with endogenous RAR gamma on RAREs, suggesting that dnRXR alpha impairs retinoid signaling by competing with endogenous RAR gamma-RXR alpha heterodimers. Histologically, the epidermis of dnRXR alpha mice showed no detectable developmental abnormalities. Surprisingly, in adult animals, the suprabasal expression of dnRXR alpha significantly reduced the ability of topically applied tRA to stimulate proliferation of undifferentiated keratinocytes in the basal layer of epidermis. RXR-selective ligands alone had no detectable effects on both normal and transgenic mouse epidermis. Accordingly, we suggest that in vivo: (1) in suprabasal keratinocytes, retinoids regulate gene transcription via RAR-RXR heterodimers in which RAR confers a predominant ligand response, whereas RXR AF-2 is required for liganded RAR AF-2 to efficiently trans-activate target genes, and (2) this suprabasal RXR-assisted mechanism indirectly regulates proliferation of basal keratinocytes likely via intercellular signaling.

Animals↗
PubMed1997

Cloning and sequence analysis of a novel insertion element from plasmids harbored by the carbofuran-degrading bacterium, Sphingomonas sp. CFO6.

Sphingomonas sp. CFO6 (a member of the alpha group of Proteobacteria) was isolated from a Washington soil by enrichment on the insecticide carbofuran as a sole source of carbon and energy. This strain has been shown to harbor five plasmids, at least some of which are required for catabolism of carbofuran. Rearrangements, deletions, and loss of individual plasmids resulting in the loss of the carbofuran-degrading phenotype were observed following treatment with heat or introduction of Tn5. Several putative insertion sequence elements of different sizes were cloned from these plasmids by trapping in pUCD800, a positive selection vector for isolation of transposable elements. Three of the most common putative IS elements (designated IS1412, IS1487, and IS1488) in the clone library were of different sizes and cross-hybridize with each other. An element hybridizing with IS1412, IS1487, and IS1488 was mobilized during growth of CFO6 at 42 degrees C and inserted into one of CFO6's plasmids (pCFO4), corresponding to a deletion in the plasmid and a loss of catabolic function. IS1412 was completely sequenced and its sequence analyzed. IS1412 is 1656 bp in length and possesses terminal partially matched inverted repeats of unequal length (17 and 18 bp). In addition, IS1412 contains an open reading frame which encodes a putative transposase with significant homology to the putative transposases of IS1380 from Acetobacter pasteurianus, HRS1 from Bradyrhizobium japonicum, and IS1247 from Xanthobacter autotrophicus. These related IS elements form part of a family of common IS elements distributed among members of the alpha group of the Proteobacteria.

Amino Acid Sequence↗
PubMed1997

Carbofuran degradation in soil profiles.

Two soils, Puyallup fine sandy loam from Puyallup, WA, and Ellzey fine sand from Hastings, FL, each with a prior history of carbofuran exposure but with different pedological and climatological characteristics, were found to exhibit enhanced degradation toward carbofuran in surface and subsurface soil layers. The treated Puyallup and Ellzey soils exhibited higher mineralization rates for both the carbonyl and the aromatic ring of carbofuran when compared to untreated soils. Disappearance rates of [14C-URL (uniformly ring labeled)] carbofuran in the treated Ellzey soil was faster than in untreated soil, and also faster in surface soil than in subsurface soil. Initial degradation patterns in the treated Ellzey soil were also different from those in the untreated soil. The treated Ellzey soil degraded carbofuran mainly through biological hydrolysis, while untreated soil degraded carbofuran through both oxidative and hydrolytic processes.

Autoradiography↗
PubMed1997

Retinoid X receptor-specific ligands synergistically upregulate 1, 25-dihydroxyvitamin D3-dependent transcription in epidermal keratinocytes in vitro and in vivo.

We have examined the mechanism by which endogenous retinoid X receptor (RXR), vitamin D3 receptor (VDR), and cognate ligands regulate nuclear 1,25-dihydroxyvitamin D3 (D3) signaling in epidermal keratinocytes from skin, a physiologic D3 target. In vitro, RXR and VDR-specific antibodies identified endogenous RXR and VDR bound to a vitamin D3-responsive element (DR3) as heterodimers (VDR-RXR). In cultured keratinocytes, 9-cis retinoic acid (9cRA), a panagonist for RXR and retinoic acid receptor (RAR), and an RXR-selective agonist, SR11237, synergized with D3 to activate DR3 via endogenous as well as overexpressed VDR-RXR, whereas both of these RXR agonists alone were ineffective. In contrast, SR11237 did not synergize with but antagonized an RAR-selective ligand activation of a retinoic acid-responsive element (DR5) via endogenous RAR-RXR. Furthermore, expression of RXR mutated in transactivation domain AF-2 inhibited endogenous VDR-RXR activity over DR3. This mutant efficiently bound to DR3 as VDR-RXR but showed reduced capacity to transactivate DR3 in response to D3 and SR11237. In vivo, D3 and SR11237 synergistically induced the naturally occurring D3-responsive 24-hydroxylase gene in epidermis of mouse skin, whereas SR11237 alone was ineffective. Our data suggest that allosteric changes caused by VDR in DR3-bound VDR-RXR do not block access of ligands to RXR. RXR ligand-induced conformational changes permit VDR-RXR, via both VDR and RXR activation function domains, to mediate maximal D3 signaling in keratinocytes.

Animals↗