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Biomedical subjects

W Liu

Publications and source records attributed to W Liu.

At least 271 records · Page 15Linked to original sources
PubMed2001

The analysis of electroretinography of diabetes mellitus.

PURPOSE: In order to get deeper understanding of Diabetic Retinopathy(DR), we analyzed and evauated the results of the amplitude and latency of F-ERG a-wave, b-wave and the total amplitudes of oscillatory potentials(OPs). METHODS: F-ERG of 105 eyes from 55 cases of DM were diagnosed by the medical department from July 1997 to July 1998. The 105 eyes were examined by ophthalmoscope and fluorescing in angiography and divided into there groups: 22 eyes with DM without DR(NDR), 56 eyes with background DR(BDR) and 27 eyes with proliferate DR(PDR). In addition, 30 eyes were regard as normal control group(NCG). We used VATA-2000 type vision electrophysiological instrument and inter-national standard for clinical ERG to do measure meat and recording automatically by computer. RESULTS: 1. The proportion of eyes number of invisible wave of a-wave, b-wave of F-ERG and Ops increased with the development of DR. 2. There were significant differences(P < 0.01) in the latency of a-wave between NCG and BDR and statistical significance(P < 0.05) between BDR and NDR. There were significant differences(P < 0.01) in the amplitude of b-wave among NCG and BDR, NCG and PDR, NDR and BDR, NDR and PDR. 3. The total amplitudes of OPs lowered with progressions of DR. There were significant differences(P < 0.01) in tota amplitudes of OPs between NCG and NDR, NCG and BDR, NDR and BDR, statistical significance(P < 0.05) between NDR and PDR. 4. There was no correlation between each index and the duration of the disease (P < 0.05). CONCLUSION: The amplitude of a-wave, b-wave, and total amplitudes are the targets for early diagnosis of DR. The combined analyses of the three indexes of ERG can determine the severity, curative effect, and prognosis of the disease.

Adult↗
PubMed2001

[Effect of increased and decreased bite force on morphology of periodontal tissues].

OBJECTIVE: The aim of this study was to observe the effect of bite force on morphology of periodontal tissues. METHODS: Animal models were induced by extracting the left maxillary molars; the left mandibular molars served as decreased bite force models; the right mandibular molars served as increased bite force models. The dynamic changes of widths of periodontal ligament and cementum were measured. RESULTS: In decreased bite force group, there were significant morphologic changes of periodontal tissues after 1 week. In increased bite force group, there was no significant change. Ligament widths were significantly different after 2, 3 weeks respectively in those two groups, compared with that in control group (P < 0.05). There were significant differences between proximal alveolar wall and distal alveolar wall in width (P < 0.05). CONCLUSION: The histological morphology is closely related to the mechanical condition. Physiological bite force is necessary for periodontal ligament to maintain its physiological structure.

Animals↗
PubMed2001

[Comparison between human sperm zona-free hamster ovum penetration assay and in-vitro fertilization].

OBJECTIVE: The research question was whether the result of human sperm zona-free hamsterovum penetration assay (SPA) could serve as an indicator for in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). METHODS: The semen samples of 22 male partners in couples with infertile marriage were assessed for their fertilizing capacity by SPA. The fertilization rate of SPA was compared with that of IVF. RESULTS: The fertilization rates of SPA and IVF were 38.6% +/- 23.5% and 53.5% +/- 28.4% respectively, and a significant correlation between SPA and IVF was observed (rs = 0.7045). CONCLUSION: The result of SPA may be used as a reference indicator for assisting fertilization, IVF or ICSI.

Animals↗
PubMed2001

Combined intraoperative iliac artery stents and femoro-popliteal bypass for multilevel atherosclerotic occlusive disease.

OBJECTIVE: To review our preliminary experience and evaluate our early results of a combined intraoperative iliac angioplasty and stenting with infrainguinal revascularization in multilevel atherosclerotic occlusive disease. METHODS: From July 1999 to April 2000, intraoperative iliac angioplasty and stenting combined with simultaneous femoro-popliteal bypass were performed on 12 lower extremities of 10 patients suffering from multilevel atherosclerotic occlusive disease. There were 8 men and 2 women, average 72 years. The indications for procedures included disabling claudication in 3 and rest pain in 7 patients. RESULTS: Eleven iliac angioplasty and stent procedures combined with simultaneous 9 femoro-popliteal by-pass and 3 femoro-femoral-popliteal bypass were performed in 12 limbs of 10 patients. Angioplasty and stent placement was technically successful in all patients. One contralateral femoral-popliteal bypass was failure after femoro-femoral-popliteal bypass. There were no additional instances of procedural or postoperative morbidity or mortality. Mean follow-up was 5 months (range 1 approximately 10 months). During the follow-up period, one femoro-infrapopliteal graft became occluded after 7 months and above-knee amputation was required. The cumulative primary patency rate of stented iliac arteries, femoro-femoral bypass grafts and femoro-popliteal bypass grafts were 100% (11/11), 100% (3/3) and 90.9% (10/11) in the follow-up period, respectively. The amputation rate was 8.3% (1/12). CONCLUSIONS: Intraoperative iliac artery PTA and stent placement can be safely and effectively performed simultaneously with infrainguinal revascularization for multilevel atherosclerotic occlusive disease by skilled vascular surgeon, using a portable C arm fluoroscopy inthe operating room. Furthermore, iliac artery PTA and stenting was valuable adjunct to distal bypass either to improve inflow and outflow, or to reduce the extent of traditional surgical intervention, and also, any angioplasty and stenting-related complications can be immediately corrected as well.

Aged↗
PubMed2001

[Synthesis and characterization of meso-tetra-(4-palmitoyloxyphenyl)porphyrin].

The meso-tetra-(4-palmitoyloxyphenyl)porphyrin(TPPPH2) was synthesized by esterification reaction with meso-tetra-(4-hydroxyphenyl)porphyrin(THPPH2) and Palmityl chloride as reactant. This product was separated and purified by column chromatography with silica gel as fixed phase and chloroform as washing agent, and characterized by means of elemental analysis, UV-visible spectrum, infrared photoacoustic spectrum and 1H NMR. The main spectra of UV, IR and 1H NMR were measured and investigated.

English Abstract↗
PubMed2001

[Analysis of the content of ten kinds of metal elements in cerebrolysin by atomic absorption spectrophotometry].

The contents of Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu and Zn in eight different brand cerbrolysins were determined by flame atomic absorption spectrophotometry. The statistical results as follows: the metal elements have significant difference between in seven kinds of Chinese products and in the cerebrolysin made by Austria. According to the results, we studied the inter relation of metal elements with medicine result, and analyzed the effect of trace elements in cerebrolysin. It provided useful data for medicine on clinical practice.

Amino Acids↗
PubMed2001

[Correction for the spectral interferences of rare-earth matrix to the determination of calcium by spectral fitting matrix projection-Kalman filter method].

The spectral interferences of trace elements from high purity rare earth will seriously affect the analytical accuracy in the ICP-AES analysis. In this work, spectral fitting matrix projection-Kalman filter method was developed and applied to correction of spectral interferences produced by rare earth matrix peaks with simple shapes in determination of calcium, and it was applied to correct spectral interferences caused by terbium oxide and dysprosium oxide respectively, and satisfactory results were obtained.

Calcium↗
PubMed2001

[Relationship between computerized cardiotocography and perinatal outcomes].

OBJECTIVE: To analyze the relationship between the parameters of computerized cardiotocography (CTG) and perinatal outcomes. METHODS: Three hundred and eight CTG examination in 190 third trimester pregnancy were performed, 46 cases in antepartum, 262 cases in intrapartum. CTG parameters including: baseline fetal heart rate (BHR), the square root of the mean squared differences (RMSSD), the proportion derived by dividing the number of differences greater than 3 beats/min by the total number (NN50), acceleration (AC), deceleration (DC), amplitude of deceleration (AMP), duration of deceleration from BHR to bottom (T1) and duration from bottom to BHR (T2), the ratio of T2 to T1 (T2/T1), square of deceleration (DS), the ratio of AMP to duration of deceleration (H/T), the ratio of DS to the product of AMP multiplied deceleration duration (S/HT), amplitude of uterine contraction (UTAMP), number of uterine contraction (UTNO), duration of uterine contraction (UTDUR), square of uterine contraction (UTS), the ratio of AMP to UTAMP (HR/HU), the ratio of DS to UTS (SR/SU), the ratio of DS to UTAMP (SR/HU). After childbirth record neonatal Apgar scores, amniotic fluid colour (COL) and volume (VOL), umbilical cord arteria blood gas analysis. RESULTS: (1) The fetal heart rate (FHR) baseline and variability . In antepartum, there were significantly relationship between BHR and Apgar (r = 0.460, P < 0.01), RMSSD and COL (r = - 0.389, P < 0.05), NN50 and COL (r = - 0.368, P < 0.05), RMSSD and actual base excess (ABE) (r = 0.904, P < 0.05), NN50 and ABE (r = 0.919, P < 0.05), AC and ABE (r = 0.943, P < 0.05), BHR and SO2 ( r = - 0.895, P < 0.05). But during intrapartum, there were no significantly relationship between the baseline and variability of CTG with the Apgar scores, the quality and color of amniotic fluid, and the indexes of blood gas analysis of umbilical artery blood. (2) The deceleration of FHR. During antepartum there were significantly relationship between Apgar and AMP (r = - 0.472, P < 0.05), Apgar and H/T (r = - 0.526, P < 0.05), COL and AMP (r = 0.447, P < 0.05), COL and H/T (r = 0.543, P < 0.05) . During intrapartum the relationship of COL and T1 was significant (r = - 0.205, P < 0.05), there were significantly relationship between PH and H/T (r = 0.386, P < 0.05), ABE and H/T (r = 0.367, P < 0.05), Apgar and UTDUR (r = 0.149, P < 0.05), Apgar and UTS (r = 0.148, P < 0.05), PO2 and UTS (r = 0.234, P < 0.05), PO2 and UTNO (r = -0.246, P < 0.05), HCO3 and UTAMP (r = - 0.265, P < 0.05), TCO2 and UTAMP (r = - 0.268, P < 0.05), HCO3 and HR/HU (r = 0.385, P < 0.01), TCO2 and HT/HU (r = 0.385, P < 0.01), ABE and HR/HU (r = 0.323, P < 0.05). CONCLUSIONS: In antepartum, the baseline and variability of FHR play a more important role in predicting prenatal outcome than any other parameters; during intrapartum deceleration become more important, but with the affect by uterin contraction, the ratio of HR/HU may be useful during intrapartum.

Amniotic Fluid↗
PubMed2000

Fdp, a new fibrocyte-derived protein related to MIA/CD-RAP, has an in vitro effect on the early differentiation of the inner ear mesenchyme.

During the course of a study aimed at isolating transcripts specifically or preferentially expressed in the inner ear, we identified a novel gene, encoding a fibrocyte-derived protein, that we named Fdp. Fdp is predicted to be a secreted 128-amino acid protein, which is highly homologous to the melanoma-inhibiting activity/cartilage-derived retinoic acid-sensitive protein (MIA/CD-RAP), a cartilage-specific protein also expressed in several tumors. Fdp and MIA/CD-RAP thus define a new family of proteins. Fdp is expressed from embryonic day 10.5 in the mesenchyme surrounding the otic epithelium. During development, these cells progressively aggregate, condense, and differentiate into cartilaginous cells forming the otic capsule, which no longer expresses Fdp, and into fibrocytes surrounding the epithelia, which strongly express Fdp. In order to address the function of Fdp, we developed an in vitro antisense oligonucleotide approach using microdissected periotic mesenchyme micromass cultures, and showed that Fdp antisense oligonucleotide treatment results in a significant reduction in chondrogenesis. Our results demonstrate that Fdp plays a role in the initiation of periotic mesenchyme chondrogenesis. Accordingly, Fdp and its human ortholog FDP, which map to chromosome 2 and band 20p11, respectively, could be candidate genes for forms of deafness associated with malformations of the otic capsule.

Amino Acid Sequence↗
PubMed2000

Yeast chromosomes have been significantly reshaped during their evolutionary history.

The structure of the first eukaryotic genome, belonging to Saccharomyces cerevisiae, has been deduced; however, very little is known about its origin. In order to trace events that led to the current state of the Saccharomyces nuclear genomes, random fragments of genomic DNA from three yeasts were sequenced and compared to the S. cerevisiae database sequence. Whereas, S. cerevisiae and Saccharomyces bayanus show perfect synteny, a significant portion of the analysed fragments from Saccharomyces servazzii and Saccharomyces kluyveri show a different arrangement of genes when compared to S. cerevisiae. When the sequenced fragments were probed to the corresponding karyotype, a group of genes present on a single chromosome of S. servazzii and S. kluyveri had homologues scattered on several S. cerevisiae chromosomes. Apparently, extensive reorganisation of the chromosomes has taken place during evolution of the Saccharomyces yeasts. In addition, while one gross duplication could have taken place, at least a few genes have been duplicated independently at different time-points in the evolution.

Chromosomes, Fungal↗
PubMed2000

pH stability of HLA-DR4 complexes with antigenic peptides.

Complexes between antigenic peptides and class II proteins of the major histocompatibility complex (MHC) trigger cellular immune responses. These complexes usually dissociate more rapidly at mildly acidic pH, where they are formed intracellularly, as compared to neutral pH, where they function at the cell surface. This paper describes the pH dependence of the dissociation kinetics of complexes between MHC proteins and antigenic peptides containing aspartic and glutamic acid residues. Some of these complexes show an unusual pH dependence, dissociating much more rapidly at pH 7 than at pH 5.3. This occurs when the carboxylate group of the aspartic or glutamic acid residue is located in a neutral pocket of the protein. In contrast, solvent-exposed carboxylate groups or carboxylate groups buried in pockets where they form salt bridges with the protein do not show this unusual pH dependence. The kinetic data having the unusual pH dependence conform closely to a model in which there is a rapid reversible equilibration between a less stable deprotonated complex and a more stable protonated complex. In this model, the pK(a) of the protonation reaction for the partially buried peptide carboxylate group ranges from 7.7 to 8.3, reflecting the strongly basic conditions required for deprotonation. One of the few peptide/MHC complexes demonstrated to play a role in autoimmunity in humans contains a buried peptide carboxylate and shows this unusual pH dependence. The relevance of this finding to understanding the chemical basis of autoimmunity is briefly discussed.

Adipokines↗
PubMed2000

N-acetylaspartylglutamate protects against transient focal cerebral ischemia in rats.

The inhibition of N-acetylated alpha-linked acidic dipeptidase (NAALADase: glutamate carboxypeptidase II) has been previously shown to protect against ischemic injury presumably through mechanisms of decreasing glutamate and increasing N-acetylaspartylglutamate (NAAG). Preventing excessive glutamate release is known to be neuroprotective. However, the role of increased NAAG is not clear. We used a middle cerebral artery occlusion model in rats to investigate the neuroprotective effect of NAAG via its action as a metabotropic glutamate (mGlu) receptor agonist. Rats received intracerebral injections of NAAG (1, 2, or 4 micromol), or a co-injection of NAAG (2 micromol) and the non-selective mGlu receptor antagonist, (R,S)-alpha-methyl-4-carboxyphenylglycine, (MCPG, 2 micromol). Immediately after the treatment, the animals received 2 h of middle cerebral artery occlusion followed by 22 h of reperfusion. Treatment with 1 or 2 micromol of NAAG significantly reduced total infarct volume. Treatment with MCPG partially attenuated the neuroprotective effect of NAAG, indicating that the protective effect of NAAG against ischemic injury may be in part mediated via activation of mGlu receptors.

Animals↗
PubMed2000

Proteolysis of the human DNA polymerase epsilon catalytic subunit by caspase-3 and calpain specifically during apoptosis.

Human DNA polymerase epsilon (pol epsilon) normally contains a 261-kDa catalytic subunit (p261), but from some sources it is isolated as a 140-kDa catalytic core of p261. This shortened form possesses normal or somewhat enhanced polymerase activity and its significance is unknown. We report here that caspase-3 and calpain can form p140 from p261 in vitro and in vivo and that during early stages of apoptosis induced in Jurkat cells by staurosporine or anti-Fas-activating antibody, p261 is cleaved into p140 by caspase-3. At later stages, activated calpain might also contribute to this conversion. The sites of cleavage by caspase-3 have been identified, and mutations at these 'DEAD boxes' resulted in cleavage-resistant enzyme. Cleavage at these sites separates the 'N-terminal catalytic core' from the 'C-terminal' regions described for p261. Cleavage does not occur during necrosis or following exposure to H(2)O(2) or methanesulfonic acid methyl ester. p140 is unlikely to be able to functionally replace p261 in vivo, since it does not bind to PCNA or the other pol epsilon subunits.

Amino Acid Sequence↗
PubMed2000

Muscarinic tone sustains impulse flow in the septohippocampal GABA but not cholinergic pathway: implications for learning and memory.

Systemic infusions of the muscarinic cholinergic receptor antagonists atropine and scopolamine (atr/scop) produce an amnesic syndrome in humans, subhuman primates, and rodents. In humans, this syndrome may resemble early symptoms of Alzheimer's disease. Behavioral studies in rats have demonstrated that the medial septum/diagonal band of Broca (MSDB), which sends cholinergic and GABAergic projections to the hippocampus, is a critical locus in mediating the amnesic effects of atr/scop. The amnesic effects of atr/scop in the MSDB have been presumed but not proven to be caused by a decrease in hippocampal acetylcholine (ACh) release after blockade of a muscarinic tone in the MSDB. Using electrophysiological recordings and fluorescent-labeling techniques to identify living septohippocampal neurons in rat brain slices, we now report that, contrary to current belief, a blockade of the muscarinic tone in the MSDB does not decrease impulse flow in the septohippocampal cholinergic pathway; instead, it decreases impulse flow in the septohippocampal GABAergic pathway via M(3) muscarinic receptors. We also report that the muscarinic tone in the MSDB is maintained by ACh that is released locally, presumably via axon collaterals of septohippocampal cholinergic neurons. As such, cognitive deficits that occur in various neurodegenerative disorders that are associated with a loss or atrophy of septohippocampal cholinergic neurons cannot be attributed solely to a decrease in hippocampal acetylcholine release. An additional, possibly more important mechanism may be the concomitant decrease in septohippocampal GABA release and a subsequent disruption in disinhibitory mechanisms in the hippocampus. Restoration of impulse flow in the septohippocampal GABA pathway, possibly via M(3) receptor agonists, may, therefore, be critical for successful treatment of cognitive deficits associated with neurodegenerative disorders such as Alzheimer's and Parkinson's disease.

Acetylcholine↗
PubMed2000

Experimental microneurosurgery of the trigeminal ganglion and ophthalmic-maxillary nerve in the rat: subtemporal fossa approach.

In the researches of the innervation relationship between trigeminal ganglion and a particular structure in the head, it is usually necessary to apply neural tracers into the ganglion for anterograde nerve tracing study or perform bilateral trigeminal nerve transecting for degeneration study. A common surgical approach for exposing these structures in the rat was to remove a piece of skull and a portion of brain. While investigating the innervation of rat's pineal gland from its trigeminal ganglion, we used a subtemporal fossa approach, whereby the mortality of the animal was remarkably reduced and the contamination of the intracranial structures by the tracer was proved to be least. This is the first description of bilateral surgeries of the trigeminal ganglion and trigeminal nerve in rat using extracranial approach. Detailed surgical procedures were presented and their advantages discussed.

Animals↗
PubMed2000

Arsenite induces apoptosis of murine T lymphocytes through membrane raft-linked signaling for activation of c-Jun amino-terminal kinase.

Because of its dual roles in acute toxicity and in therapeutic application in cancer treatment, arsenic has recently attracted a renewed attention. In this study, we report NaAsO(2)-induced signal cascades from the cell surface to the nucleus of murine thymic T lymphocytes that involve membrane rafts as an initial signal transducer. NaAsO(2) induced apoptosis through fragmentation of DNA, activation of caspase, and reciprocal regulation of Bcl-2/Bax with the concomitant reduction of membrane potential. We demonstrated that NaAsO(2)-induced caspase activation is dependent on curcumin-sensitive c-Jun amino-terminal kinase and barely dependent on SB203580-sensitive p38 kinase or PD98059-sensitive extracellular signal-regulated kinase. Additionally, staurosporine, which severely inhibited the activation of mitogen-activated protein (MAP) family kinases and c-Jun, partially blocked the NaAsO(2)-mediated signal for poly(ADP-ribose) polymerase (PARP) degradation. Potentially as the initial cell surface event for intracellular signaling, NaAsO(2) induced aggregation of GPI-anchored protein Thy-1 and superoxide production. This Thy-1 aggregation and subsequent activation of MAP family kinase and c-Jun and the degradation of PARP induced by NaAsO(2) were all inhibited by DTT, suggesting the requirement of interaction between arsenic and protein sulfhydryl groups for those effects. beta cyclodextrin, which sequestrates cholesterol from the membrane rafts, inhibited NaAsO(2)-induced activation of protein tyrosine kinases and MAP family kinases, degradation of PARP, and production of superoxide. In addition, beta cyclodextrin dispersed NaAsO(2)-induced Thy-1 clustering. These results suggest that a membrane raft integrity-dependent cell surface event is a prerequisite for NaAsO(2)-induced protein tyrosine kinase/c-Jun amino-terminal kinase activation, superoxide production, and downstream caspase activation.

Animals↗
PubMed2000

Role for the p53 homologue p73 in E2F-1-induced apoptosis.

The transcription factor E2F-1 induces both cell-cycle progression and, in certain settings, apoptosis. E2F-1 uses both p53-dependent and p53-independent pathways to kill cells. The p53-dependent pathway involves the induction by E2F-1 of the human tumour-suppressor protein p14ARF, which neutralizes HDM2 (human homologue of MDM2) and thereby stabilizes the p53 protein. Here we show that E2F-1 induces the transcription of the p53 homologue p73. Disruption of p73 function inhibited E2F-1-induced apoptosis in p53-defective tumour cells and in p53-/- mouse embryo fibroblasts. We conclude that activation of p73 provides a means for E2F-1 to induce death in the absence of p53.

Animals↗