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Biomedical subjects

X Yang

Publications and source records attributed to X Yang.

At least 901 records · Page 50Linked to original sources
PubMed1996

[Effects of ginkgo plus on hypoxic pulmonary hypertension in rats].

We examined the effects of Ginkgo Plus on the pulmonary hemodynamics and right ventricular hypertrophy in rats exposed to isobaric chronic hypoxia. The rats treated with chronic hypoxia developed pulmonary hypertension and right ventricular hypertrophy. Ginkgo Plus reduced significantly the hypoxia-induced increase of mean pulmonary arterial pressure and pulmonary vascular resistance as well as the ratio of right ventricular weight vs left ventricular plus septal weights. The results suggested that Ginkgo Plus could relieve the hypoxic pulmonary hypertension.

Animals↗
PubMed1996

[The level of platelet activating factor in blood of rats with hypoxic pulmonary hypertension].

Because hypoxia is a known predisposing factor for pulmonary hypertension, we investigated the effects of hypoxia and platelet activating factor (PAF) on the development of pulmonary hypertension in rats. Male Wistar rats were made hypoxic by placing them in a isobaric hypoxic chambar (O2 = 10%) for 3 weeks; the rats developed pulmonary hypertension and right ventricular hypertrophy. We found that PAF level in blood of rats were significantly elevated at 2-3 weeks of hypoxia (280.8 +/- 119.7 ng/ml and 324.2 +/- 67.6 ng/ml vs 148.3 +/- 60.2 ng/ml). Therefore, we conclude that PAF plays a central role in mediating hypoxia-induced pulmonary hypertension.

Animals↗
PubMed1996

[T-cell receptor gene rearrangement analysis of midline malignant reticulosis: a PCR study of 14 cases].

Using PCR method, we analyzed the gene rearrangement of T-cell receptor chain (TCR-beta) in 14 cases of midline malignant reticulosis (MMR). Our results showed that there were non-germline, monoclonal rearrangements of TCR-beta in 12 of 14 cases of MMR (85.7%). In contrast, the same rearrangement pattern was found only in 6 of 10 cases of lymph node based T-cell lymphoma. The cases of reactive lymphoid hyperplasia were of a polyclonal rearrangement pattern. This study suggests that MMR is a monoclonal T-cell neoplasm and PCR method is a rapid, facilitated and useful method for the detection of clonalities of T-cell proliferations.

Gene Rearrangement, beta-Chain T-Cell Antigen Rece↗
PubMed1996

[Determination of copper and cadmium in water by continuous flow analysis].

A continuous flow analysis system for the preconcentration of Cu2+ and/or Cd2+ in water was developed. Trace copper or cadmium in water could be concentrated on activated carbon particles packed in micro column at pH > or = 9.0. The adsorbed analyte was eluted with 0.5 ml 2.5% nitric acid and determined by flame atomic absorption spectrometry. A sample size of 10-25 ml sufficed for the determination of copper2+ or cadmium at a level as low as microgram/L. The relative standard deviation of 6 parallel determinations was 4.3% for copper and 11% for cadmium. The proposed method was applied to the determination of copper and cadmium in natural water with a recovery of 84.4%-118%.

Cadmium↗
PubMed1996

[An experimental study on corneal nerve regeneration after penetrating keratoplasty with long-term cryopreserved rabbit corneas].

OBJECTIVE: To observe the morphology of rabbit corneal nerve regeneration in the grafts after penetrating keratoplasty (PKP) with long-term cryopreserved homogeneous donor material. METHODS: Both long-term cryopreserved and short-term moist-chamber preserved fresh rabbit corneas were applied in the keratoplasty. By means of glyoxylic-acid induced fluorescence (GIF) and acetylcholine esterase (AChE) staining histochemical techniques, the morphological features of adrenergic and cholinergic nerve regeneration were monitored under light microscope in those grafts from ten days to eight months after surgery. RESULTS: During various intervals, the morphological changes of neural reinnervation were similar in the two groups, and numerous subepithelial nerves that showed random changes in direction and caliber were apparent. The nerve endings in the epithelium were few. CONCLUSIONS: The cryopreservative procedures do not affect neural regeneration under light microscope. The depressed tactile sensitivity following the surgery is correlated with nerve endings in the epithelium subnormal in number and with the regeneration of corneal nerves abnormal in distribution and morphology.

Adrenergic Fibers↗
PubMed1996

[Changes on level and expression of endothelin-1 in the lungs of rats with hypoxic pulmonary hypertension].

The aim of the present study was to determine whether mRNA for endothelin-1 (ET-1) was present and changed in the lungs of rats exposed to chronic hypoxia, cRNA probes for rat ET-1 and c-fos were labelled by in vitro transcription with digoxigenin-UTP for in situ hybridization. Endothelin-1 like immunoactivity (ET-1-LI) in plasma as well as in lung homogenate was measured by radio-immunoassay. The results showed that the vascular endothelia cells of pulmonary artelics and the bronchiolar epithelial cells were strongly positive for the ET-1 probe. The perivascular and peribronchiolar smooth muscle were positive for the c-fos probe primarily. Whereas, there were little expression of ET-1 and c-fos in the rat lungs in controls. There were significant increase of ET-1-LI levels in rats exposed to hypoxia for 3 weeks, the concentration in venous samples was 3.85 +/- 1.52ng/L (P < 0.05 as compared with the control groups), in arterial sample was 4.72 +/- 1.66ng/L (P < 0.05) and in lung tissue was 2.06 +/- 0.68ng/g wet lung weight (P < 0.05). It is suggested that chronic hypoxia elevated the mean pulmonary arterial pressure, caused vessel remodelling and right ventricular hypertrophy. These changes were accompanied by an increase of ET-1 in plasma and lung homogenate. The expression and production of ET-1 were localized to endothelium and airway epithelium in the lungs.

Animals↗
PubMed1996

A dynamic and quantitative study of pattern visual evoked potentials and gamma-aminobutyric acid neurones in the lateral geniculate nucleus and the visual cortex of monocular deprivation cats.

PURPOSE: To assess the effects of monocular lid closure during critical period on cortical activity. METHOD: Pattern visual evoked potentials (PVEP) of the normal and the monocular deprivation (MD) cats were dynamically measured and the number of gammaaminobutyric acid immunopositive (GABA-IP) neurones of the area 17 of the visual cortex and the lateral geniculate nucleus (LGN) was quantitatively compared by using immunohistochemical method (ABC). RESULTS: The amplitude of the N1-P1 attenuated in deprived eyes (DE), NE/DE at postnatal week (PNW) 7-8 (P < 0.05), NE/DE at PNW 15-16 (P < 0.01); while P1 latency delayed, NE/DE at PNW 7-8 (P > 0.05), NE/DE at PNW 15-16 (P< 0.05). The numbers of GABA-IP neurones in layer A1 of the ipsilateral LGN and in layer A of the contralateral LGN, compared to those in the corresponding normal laminae, were not significant at PNW 7-8 and PNW 11-12 (P > 0.05), while in the same cats a reduction in the number of GABA-IP neurones was found in layer IV of area 17 at PNW 11-12 (P < 0.05). However, with longer survival of 3-4 weeks in duration, the numbers of GABA-IP neurones in the deprived laminae of LGN were remarkably reduced (P < 0.05). CONCLUSIONS: The amplitude of N1-P1 components is sensitive to the effects of monocular deprivation. Monocular deprivation in cats during critical period leads to dramatic changes of the number of GABA-IP neurones in the LGN and cortical layer IV receiving inputs from the deprived eye in cats. The deprivation-induced reduction in GABA-IP neurones is delayed in the LGN compared with the visual cortex. PVEP of the MD cats is consistent with the damage of its GABA system in visual cortex.

Animals↗
PubMed1996

[Clinical application of enzyme linked immunosorbent assay in testing antibodies against cochlear tissues and nerve tissues].

Fifty-two patients with idiopathic sensorineural hearing loss and 20 controls were examined by enzyme linked immunosorbent assay (ELISA) with cow cochlear antigen (CCAg) and cow cochlear nerve antigen (CCNAg). The antibody level against CCAg was 0.3811 +/- 0.743 in the control group and 0.9241 +/- 0.2408 in the experimental group (OD, x +/- 2s, P < 0.01). Compared with the x +/- 2s antibody level of the control group, the antibody level of 24 of 52 (46%) patients of the experimental group was positive. The antibody level against CCNAg was 0.2254 +/- 0.382 in the control group and 0.2331 +/- 0.656 in the experimental group (P > 0.05). Compared with the x +/- 2s antibody level of the control group, the antibody level of 6 of 52 patients (11.5%) of the experimental group was elevated. It is suggested that ELISA method can be used as quantitatively in the diagnosis of autoimmune inner ear diseases. Moreover, the serum antibodies against CCNAg detected in this experiment suggest that some of autoimmune inner diseases might be retrocochlear.

Adolescent↗
PubMed1996

[Effect of shenmai injection on local defence mechanism in peritoneal dialysis rats].

The local defence mechanism of peritoneal cavity plays an important role in preventing peritonitis during peritoneal dialysis. In this experiment, the effect of Shenmai injection (SI) on the defence mechanism was studied in the remnant kidney model. The results showed that the SI which was added into dialysate could significantly increase the concentration of IgG, C3 in peritoneal cavity (P < 0.05). There was insignificant change in the number of peritoneal macrophages, but the index and the percentage of phagocytosis had the tendency to increase (P > 0.05). SI also relieved the injury of peritoneal mesothelia cells. All these results suggested that the SI had the ability to augment the peritoneal local defence mechanism.

Animals↗
PubMed1996

Regulation of insulin-like growth factor I receptor expression by the pure antiestrogen ICI 182780.

Insulin-like growth factor I (IGF-I) is a mitogen for human breast cancer cells both in vivo and in vitro. We demonstrate here that the antiestrogen ICI 182780 (ICI) at 10(-8) m decreases IGF-I receptor (IGF-IR) mRNA levels by 70% after treatment for 48 h. Measurements of mRNA stability indicate that the half-life of IGF-IR mRNA is approximately 3 h. Estradiol treatment increases the half-life of the IGF-IR mRNA to approximately 6 h and the level of IGF-IR gene transcription by 1.8-fold, whereas ICI treatment not only decreases the IGF-IR transcription rate by 50% but also decreases the IGF-IR mRNA half-life to less than 3 h. Affinity labeling studies with [125I]-IGF-I show 35% increased labeled IGF-I to MCF-7 cell membrane following estradiol treatment and 40% decreased labeling following ICI treatment. We also demonstrate that ICI attenuates IGF-I-stimulated growth. Our data suggest that attenuation of IGF-I responsivity by ICI may be due in part to reducing the IGF-IR expression.

Breast Neoplasms↗
PubMed1995

Recombination between heterologous linear and circular mitochondrial plasmids in the fungus Neurospora.

A strain of Neurospora intermedia from China contains five prominent extragenomic mitochondrial plasmids: three linear elements called zhisi plasmids, and two circular plasmids, Harbin-1 and -2. In one subculture, levels of four plasmids (all three zhisis and Harbin-1) fell to undetectable values and two novel linear plasmids appeared, Harbin-L and -L2, as well as a new small circular plasmid, Harbin-0.9. Cross-hybridization of restriction fragments and DNA sequencing showed that the Harbin-L plasmid was composed of parts of the circular Harbin-1 plasmid and of one of the linear zhisi plasmids. A model is presented in which the Harbin-1 and zhisi plasmids are present within the same mitochondrion, and crossovers at two separate 7 bp sites of sequence identity effectively insert part of the circular Harbin-1 DNA into a zhisi linear plasmid, simultaneously deleting part of the zhisi element. The small plasmid Harbin-0.9 is a fragment of the Har-1 plasmid, and seems to be another product of the recombination process that created Har-L. Recombination of this type could have contributed to the wide array of mitochondrial plasmids found in natural populations of Neurospora.

Base Sequence↗
PubMed1995

Streptolydigin resistance can be conferred by alterations to either the beta or beta' subunits of Bacillus subtilis RNA polymerase.

Rifampicin and streptolydigin are antibiotics which inhibit prokaryotic RNA polymerase at the initiation and elongation steps, respectively. In Escherichia coli, resistance to each antibiotic results from alterations in the beta subunit of the core enzyme. However, in Bacillus subtilis, reconstitution studies found rifampicin resistance (RifR) associated with the beta subunit and streptolydigin resistance (StlR) with beta'. To understand the basis of bacterial StlR, we isolated the B. subtilis rpoC gene, which encodes a 1,199-residue product that is 53% identical to E. coli beta'. Two spontaneous StlR mutants carried the same D796G substitution in rpoC, and this substitution alone was sufficient to confer StlR in vivo. D796 falls within Region F, which is conserved among the largest subunits of prokaryotic and eukaryotic RNA polymerases. Among eukaryotes, alterations in Region F promote resistance to alpha-amanitin, a toxin which inhibits transcription elongation; among prokaryotes, alterations in Region F cause aberrant termination. To determine whether alterations in the beta subunit of B. subtilis could also confer StlR, we made three StlR substitutions (A499V, G500R, and E502V) in the rif region of rpoB. Together these results suggest that beta and beta' interact to form an Stl binding site, and that this site is important for transcription elongation.

Amino Acid Sequence↗
PubMed1995

Overexpression of the hyaluronan receptor RHAMM is transforming and is also required for H-ras transformation.

Overexpression of the RHAMM gene by transfection into fibroblasts is transforming and causes spontaneous metastases in the lung. H-ras-transformed fibrosarcomas transfected with a dominant suppressor mutant of RHAMM exhibit a so-called revertant phenotype and are completely nontumorigenic and nonmetastatic. Conversely, fibroblasts stably expressing low levels of RHAMM as a result of antisense transfection are resistant to ras transformation. Collectively, these results indicate that RHAMM acts downstream of ras. The loss of functional RHAMM ablates signaling within focal adhesions, in particular changes in focal adhesion kinase phosphorylation, and as a result these focal adhesions are unable to turn over in response to hyaluronan. These results provide evidence of the oncogenic potential of a novel extracellular matrix receptor and establish a functional link between transformation by ras and signaling within focal adhesions that are required for transformation by this oncogene.

Amino Acid Sequence↗
PubMed1995

On the functional overlap between two Drosophila POU homeo domain genes and the cell fate specification of a CNS neural precursor.

The approximately 200 distinct neurons comprising each hemisegment of the Drosophila embryonic CNS are derived from a stereotypic array of approximately 30 progenitor stem cells, called neuroblasts (NBs). Each NB undergoes repeated asymmetric divisions to produce several smaller ganglion mother cells (GMCs), each of which, in turn, divides to produce two neurons and/or glia cells. To understand the process by which cell type diversity is generated in the CNS, we are focusing on identifying genes that affect cell identity in the NB4-2 lineage from which the RP2 motoneuron is derived. We show here that within the early part of the NB4-2 lineage, two closely linked and structurally related POU homeo domain genes, pdm-2 (dPOU28) and pdm-1 (dPOU19), both encode proteins that accumulate to high levels only in the first GMC (GMC4-2a) and not in its progeny, the RP2 motoneuron. Our results from the genetic and developmental analysis of pdm-1 and pdm-2 demonstrate that these genes are not required for the birth of GMC4-2a; however, they are both involved in specifying the identity of GMC4-2a and, ultimately, in the genesis of RP2 neurons, with pdm-2 being the more dominant player in this process. In mutant animals where both pdm-1 and pdm-2 functions are removed, GMC4-2a fails to express markers consistent with a GMC4-2a identity and no mature (Eve protein expressing) RP2 neurons are produced. We demonstrate that in some mutant combinations in which no mature RP2 neurons are produced, some GMC4-2a cells can nevertheless divide. Hence, the failure of the POU mutants to produce mature RP2 neurons is not attributable to a block in GMC4-2a cell division per se but, rather, because the GMC4-2a cells fail to acquire their correct cellular identity.

Animals↗
PubMed1995

Fluorenylalkanoic and benzoic acids as novel inhibitors of cell adhesion processes in leukocytes.

A series of fluoren-9-ylalkanoic and alkylbenzoic acids was prepared as simplified analogues of a previously reported series of antiinflammatory agents which act to inhibit neutrophil recruitment into inflamed tissue. The previous compounds ("leumedins") contained (alkoxycarbonyl)amino or benzoic acid moieties tethered to a fluorene ring. This functionality was replaced with simple structural elements. The new compounds were, in general, found to be more potent than the earlier series at inhibiting adherence of neutrophils to serum-coated wells or endothelial cells in vitro. Compound 9 was approximately 10-fold more potent than the previously reported FMOC-phenylalanine, of which it is an analogue. Similarly, compound 19 was superior in potency to its first generation progenitor, NPC 16570. The new compounds were shown to inhibit neutrophil adherence under conditions in which adherence is mediated by Mac-1 (CD11b/CD18) and LFA-1 (CD11a/CD18); they thus appear to target beta 2-integrins in their antiadhesion activity. These compounds provide a departure point for the further development of new cell adhesion inhibitors which should exhibit enhanced potency and a more selective mode of action.

Benzoates↗