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Biomedical subjects

C Liu

Publications and source records attributed to C Liu.

At least 487 records · Page 27Linked to original sources
PubMed1998

[Activation of insulin-like growth factor 1 gene expression in growing rat condyle by functional mandibular protrusion].

OBJECTIVE: We studied the changes of the IGF-1 mRNA expression in condylar cartilage to elucidate the biomolecular mechanism of mandibular advancement. METHODS: Sixty 5-week-old male rats were randomly divided into experimental and control groups. The mimic functional appliances were used in experimental group. The rats were sacrificed after 1, 3, 7, 14, 21 and 28 days to study the expression of IGF-1 mRNA by in situ hybridization. RESULTS: The results showed IGF-1 mRNA expression in the condylar cartilage. The transitional and maturational layers had the most abundant IGF-1 mRNA, and the IGF-1 mRNA abundance of germinal layer is higher than that of synovial and fibrous layers. Functional mandibular protrusion activated the IGF-1 mRNA expression and it began to increase after 3 days of the experiment, and the changes were most significant in 7-14 days. CONCLUSION: This suggested that the condylar cartilage growth and remolding after functional protrusion might be caused by IGF-1 gene expression activation.

Animals↗
PubMed1998

[Long-term follow-up study of postoperative revascularization in childhood moyamoya disease: results of 226 cases].

OBJECTIVE: To study the long-term results of 226 patients with moyamoya disease ased below 15 years and to report the modified method of extra-intracranial arterial anastomosis and encephalo-myo-arterio-syn-anastomosis, etc. METHOD: The mean follow-up period was 15.5 years (range 8 - 19 years). The results were obtained from the pre- and postoperative cerebral angiographic examination, MRI, CT, cerebrovascular Doppler ultrasonography, Glasgow Outcome Scale (GOS), intelligence quotient (IQ) as classified by Taft and neurological symptoms. RESULT: Of the 226 patients with childhood moyamoya disease, 64 (28%) recovered in completely, 69 (31%) in improved markedly, and 46 (20%) improved slightly. 43 patients (19%) had no changes and 4 (2%) died. The effective rate of the operation was 79%. CONCLUSION: The modified direct anastomosis and encephalo-myo-arterio-synagiosis played a role in this improvement by increasing CBF after the operation. A significant correlation is found between the postoperative effect and the stages of preoperative angiograms.

Adolescent↗
PubMed1998

[Endovascular treatment of carotid-cavernous sinus fistulae].

OBJECTIVE: To treat carotid-cavernous sinus fistulae mmunications between 43 patients with endovascular procedure. METHOD: Of the 43 patients 37 were male and 6 female. Traumatic and spontaneous CCF were noted in 39 and 4 patients respectively. 36 patients with CCF were given ICA alone, both internal and external carotid arteries in 7. Fistulae occlusion in 31 patients and ICA obliteration in 12 patients were achieved with transarterial detachable balloon technique. External carotid feeding arteries were embolized with silk suture in 7 patients. RESULT: Angiographic and clinical cure wer obtained in 39 patients and improved in 4. One patient was complicated by hemiplegia postoperatively. CONCLUSION: Endovascular balloon embolization is the first method of choice in dealing with carotid-cavernous fistulae.

Adolescent↗
PubMed1998

[DNA extraction and sex determination of human skeletal remains].

DNA was extracted from human bones remained for 3 to 15 years by using the method developed in our laboratory. A pair of X-Y homologous primer were used to amplify the specific DNA fragments of Amelogenin gene. All the 35 samples yielded correct results. Our method is rapid, sensitive and reliable for the sex determination of skeletal remains.

Amelogenin↗
PubMed1998

[Antagonism of the novel cholinolytic tricyclopinate on nicotinic and muscarinic cholinergic receptors].

Tricyclopinate hydrochloride(TCPN.HCl) and methiodide(TCPN.CH3I) have been identified as new chemical entities. The effects of these two compounds on central and peripheral nicotinic and muscarinic cholinergic receptor activities were investigated. Excitation of the central nicotinic receptors by nicotine produced convulsions in mice. The dose-response curves of nicotine for producing convulsions were shifted rightward by TCPN.CH3I in a paralled manner. Excitation of the central muscarinic receptors by arecoline produced tremors in mice. TCPN.HCl was shown to prevent arecoline-induced tremors. In isolated guinea-pig ileum preparations. TCPN.HCl was found to antagonize nicotine-induced contractions due to excitation of ganglionic nicotinic receptors. In xenopus laevis embryo neuron-muscle co-cultured cells, TCPN.HCl blocked spontaneous miniature endplate currents, and showed preference to blocking the nicotinic receptor ion channels, which had a long open time, and high current amplitude. The anticholinergic effects of TCPN.CH3I were weaker than those of TCPN.HCl. In conclusion, TCPN.HCl has potent effects against nicotinic and muscarinic receptors in the central and periphery nervous systems.

Animals↗
PubMed1998

[In situ hybridization with digoxigenin-labelling oligonucleotide: an practical approach to skeletal tissues].

The purpose of this study was to investigate the in situ hybridization technique of paraffin-embedded skeletal tissues by non-radioactive labelling oligonucleotide, Five six-week-old male SD rats were selected and the proximal epiphyseal growth plates of bilateral tibiae were removed to be decalcified in 0.5 mol/L EDTA. The tissues were embedded by paraffin and the sections were treated and hybridized with RNase-free reagents. Control groups were set to testified the sensitivity and the specificity of the experiment. The results showed that this method preserved the integrate structures and effectively detected the mRNA of the tissues. These indicated that it was an efficient and practical approach to the biomolecular research of skeletal tissue.

Animals↗
PubMed1998

[Detection of Toxoplasma gondii DNA in human lymph node tissue by in situ hybridization].

AIM: To detect the presence of Toxoplasma gondii in lymph node tissue in patients with Toxoplasma infection. METHODS: T. gondii (RH strain) specific DNA fragment clones were obtained by using PCR and gene recombination technique. The DNA fragments used as hybridization probes were labelled with digoxigenin by random primer method. The technique of in situ hybridization (ISH) was used to detect T. g DNA in the lymph node sections. RESULTS: Four out of 120 samples T. g DNA were found positive, one with Hodgkin's disease (HD) (1/32), one with non-Hodgkin's lymphoma (NHL) (1/41) and 2 with chronic lymphadenitis (CL) (2/47). The total positive rate was 3.3%. It was demonstrated that this highly specific probe could detect 10 pg of the total RH strain T. g DNA. CONCLUSION: ISH was applicable in detecting pathogens in the lymph node tissues of individuals with Toxoplasma infection.

Animals↗
PubMed1998

[A study on processing of the root of Pueraria lobata (Willd.) ohwi by HPLC].

OBJECTIVE: To study the changes of active components in the root of Pueraria lobata after processing. METHOD: Using HPLC, with a C18 column, MeOH-H2O-CHCl3(25:75:1) as mobile phase, and flow rate 1 ml/min. RESULT: The Puerarin in different processed products of the drug is increased in content, but gets seriously destroyed if processed by carbonizing. CONCLUSION: The Puerarin content in the root of Pueraria lobata is affected by drug-processing.

Chromatography, High Pressure Liquid↗
PubMed1998

[Genome shift of hepatitis E virus in Asia].

Dideoxy chain termination method was applied to sequence hepatitis E virus structure gene of Asia isolates, cDNA sequence and amino acid residues were determined. The results showed that among Asia countries: Indian, Burma, China, Pakistan and Kirghiz Republic, Hepatitis E virus genome shifted within the range of 5% and amino acid residues shifted within 1% compared with Mexico isolate. Asia Hepatitis E virus isolates have limited genome shift, which suggests recombinant Hepatitis E vaccine based on Asia HEV gene might protect all HEV infection in this area.

Amino Acid Sequence↗
PubMed1998

[Detection of serum hepatitis B virus DNA in patients with various chronic liver diseases].

With established competitive polymerase chain reaction (PCR) method, serum HBV DNA concentration was determined in 125 patients with primary hepatic carcinoma(n = 38), liver cirrhosis (n = 36) and chronic hepatitis (n = 51) with different serum HBV immunological markers. The results showed that: (1) No significant variation of HBV DNA concentration was detected in patients with different chronic liver diseases; (2) About one third of the examined patients whose five serum HBV markers were negative and anti-HBs were positive showed low level of viral replications; (3) The total concentration of HBV DNA in the patients with positive HBeAg were significantly higher than that in patients positive for anti-HBe, but also found a high HBV DNA concentration in some of the latter. It suggests that the manner of viral replication were not correlated with the period of the chronic liver disease. So HBV replicative status may not be completely determined only by seroconvertion of HBeAg to anti-HBe.

Adolescent↗
PubMed1998

[Mechanism of specific effects of transient electromagnetic pulses on cell model].

In this paper, a facilitated cell model has been built to analyze the electromagnetic pulses (EMP) induced transmembrane potentials. The analysis shows that the athermal biological effects are caused by micropores on the membrance, not directly by transmembrane potentials. These micropores are enlarged by weak transient EMP and finally lead to membrane openings to make ions cross. The electroporation effects are used to explain the specific response of biological cells to transient EMP.

Cell Membrane↗
PubMed1998

[Application of computer simulation in the study of vibrational distributions for the products from energy transfer reaction].

The method of computer simulation in the study of vibrational distributions for the products from the energy transfer reaction is discussed. Taking the Ar (3P(0.2)) + PCl --> PCl (A3II) reaction as an example, we analysed the process of the simulation and the problems that should be paid attention to. The Franck-Condon factors of PCl (A3II --> X3sigma(-1)) are reported for the first time.

English Abstract↗
PubMed1998

Testicular volume in Taiwanese boys.

BACKGROUND: Testicular volume is used to evaluate male growth and development. Since the volume of the testes varies in different races, data for Taiwanese boys are essential to assess normal testicular growth. METHODS: Testicular volume was measured using Prader's orchidometer in 430 boys aged 0-14 years. RESULTS: Testicular growth was minimal before nine to 10 years of age. The mean testicular volume (mean of left and right testes) was 1.3 +/- 0.3 ml in newborns, 1.8 +/- 0.5 ml at six years of age and 9.1 +/- 3.5 ml at 12 years of age. CONCLUSIONS: Data on the normal values of testicular volume in Taiwanese boys will be helpful in assessing the growth of normal individuals as well as in patients with testicular or hormonal disorders.

Adolescent↗
PubMed1998

The reproducibility of muscle and joint tenderness detection methods and maximum mandibular movement measurement for the temporomandibular system.

The purpose of this study was (1) to evaluate the reproducibility of two masticatory muscle and joint tenderness detection methods; (2) to evaluate the reproducibility of maximum mandibular movement measurements; and (3) to investigate factors influencing examiner agreement. The tenderness assessment procedures involved application of a standard pressure for 2 seconds over four anatomically defined masticatory muscle sites, one control forehead site, and two temporomandibular joint sites on each side of the face. One technique utilized a pressure algometer (PAP), while the other technique required that a trained examiner apply pressure with the index fingertip (FPP). Seventy-two subjects (36 patients and 36 controls) were evaluated in a single-blind study design. Control subjects were matched for age, gender, and race with temporomandibular disorder subjects. Each subject was examined twice with each of the described methods in a randomized, fully balanced sequence by calibrated examiners. Tenderness levels were determined by the subject via self-report of pain upon pressure using a standard set of verbal descriptors. Maximum pain-free, active, and passive opening, and maximum active right and left lateral movements were measured using a millimeter ruler. Intraclass correlation coefficients (ICC) for the tenderness assessment methods ranged from 0.220 to 0.739 for the FPP method and from 0.391 to 0.880 for the PAP method. ICCs for mandibular movement measurement were much less variable, ranging from 0.59 to 0.68 for lateral movement and from 0.78 to 0.93 for opening movement. These results indicate good to excellent agreement between calibrated examiners for mandibular movement measurement and for tenderness assessment methods at two masseter (i.e., superficial and deep) and the anterior temporalis sites. Only fair agreement was found for the middle temporalis and lateral TMJ capsule sites using these methods.

Adult↗
PubMed1998

Aggregation in aqueous solutions of bovine lens gamma-crystallins: special role of gamma(s).

PURPOSE: To study the aggregation of bovine gamma-crystallins in aqueous solutions and the effect of gamma(s)-crystallin on the aggregation of other gamma-crystallins. METHODS: Aggregation in aqueous solutions of gamma(s)-, gammaII-, and gammaIVa-crystallin was monitored by quasielastic light scattering. Aggregation in mixtures of gamma(s)- and gammaII-crystallin, and gamma(s)- and gammaIVa-crystallin, was also monitored by light scattering. RESULTS: All of the gamma-crystallins studied formed large aggregates (or "megamers") in aqueous solutions. However, each protein differed in the relative rates of formation of megamers. Gamma(s)-crystallin formed megamers much more slowly than gammaII- and gammaIVa-crystallin. In solutions containing mixtures of gammaII and gamma(s), and gammaIVa and gamma(s), gamma(s)-crystallin significantly suppressed the aggregation of gammaII- and gammaIVa-crystallin. Megamerization seemed to be associated with thiol oxidation in these proteins. CONCLUSIONS: Gamma-crystallins undergo aggregation in which a small fraction of the proteins form a few large aggregates, whereas the larger proportion of the proteins remain monomeric. This suggests that the megamerization is preceded by an initial modification of the protein. The modification is associated with the thiol groups, and only such modified protein species participate in megamerization. The presence of gamma(s) significantly slows the megamerization of gammaII- and gammaIVa-crystallin. This fact, together with the previous finding that gamma(s) strongly reduces the phase separation temperatures of the gamma-crystallins, suggests that gamma(s)-crystallin plays an important role in suppressing the formation of light-scattering elements and helps maintain lens transparency.

Animals↗
PubMed1998

Alpha2-adrenergic agonists selectively activate extracellular signal-regulated kinases in Müller cells in vivo.

PURPOSE: Alpha2-adrenergic agonists have specific and selective effects on the retina to induce expression of basic fibroblast growth factor and to protect photoreceptors. This work explores the signaling pathway that mediates these effects. METHODS: Alpha2-adrenergic agonists xylazine and clonidine were administered systemically to male adult Sprague-Dawley rats. The activation state of extracellular signal-regulated kinases (ERKs) in the retina was assessed by immunoblot analysis, using antibodies that specifically recognize the dually phosphorylated forms of p44/p42 ERKs. Localization of phosphorylated ERKs was determined by immunocytochemistry. RESULTS: Intramuscular injection of 6 mg/kg xylazine induced an increase in ERK phosphorylation in the retina within 30 minutes that lasted 3 hours. Xylazine induced ERK phosphorylation at 1 mg/kg and reached a maximum at 10 mg/kg. Injection of clonidine also induced ERK phosphorylation in the retina. Yohimbine, a specific alpha2-adrenergic antagonist, completely prevented the induction of ERK phosphorylation. Immunocytochemical studies showed that the increase in ERK phosphorylation occurred mainly in Müller cells. In the brain, xylazine injection resulted in a decrease in ERK phosphorylation. CONCLUSIONS: Our results indicate that systemically administered alpha2-adrenergic agonists selectively activate ERKs in retinal Müller cells. The induced activation of ERKs in Müller cells is probably one of the early events that result in photoreceptor protection. These results also indicate that Müller cells are unique in response to alpha2-adrenergic agonists and imply a role for Müller cells in alpha2-adrenergic agonist-induced photoreceptor protection.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1997

Regulated human erythropoietin receptor expression in mouse brain.

Erythropoietin (Epo) is known for its role in erythropoiesis and acts by binding to its receptor (EpoR) on the surface of erythroid progenitors. EpoR activity follows the site of hematopoiesis from the embryonic yolk sac to the fetal liver and then the adult spleen and bone marrow. Expression of EpoR has also been observed in selected cells of non-hematopoietic origin, such as the embryonic mouse brain during mid-gestation, at levels comparable to adult bone marrow. EpoR transcripts in brain decrease during development falling by birth to less than 1-3% of the level in hematopoietic tissue. We have now recapitulated this pattern of expression using a human EpoR transgene consisting of an 80-kb human EpoR genomic fragment. The highest level of expression was observed in the embryonic yolk sac and fetal liver, analogous to the endogenous gene, in addition to expression in adult spleen and bone marrow. Although activity of this transgene in brain is initially lower than the endogenous gene, it does exhibit the down-regulation observed for the endogenous gene in adult brain. The expression pattern of hybrid transgenes of an hEpoR promoter fused to beta-galactosidase in 9. 5-day embryos suggested that the hEpoR promoter region between -1778 and -150 bp 5' of the transcription start site is necessary to direct EpoR expression in the neural tube. EpoR expression in the neural tube may be the origin of the EpoR transcripts detected in brain during development. These data demonstrate that both the mouse and human EpoR genes contain regulatory elements to direct significant levels of expression in a developmentally controlled manner in brain and suggest that in addition to its function during erythropoiesis, EpoR may play a role in the development of selected non-hematopoietic tissue.

Animals↗