Biomedical subjects

Yun Liu

Publications and source records attributed to Yun Liu.

At least 109 records · Page 6Linked to original sources

PubMed2004

[Studies on the ploymorphic of sperm of F2 hybrids of red crucian carp x common carp].

AThe ultrastructures of the sperm of F2 hybrids of red crucian carp x common carp were studied by using scanning and transmission electron microscope. The sperm of the F2 hybrids consisted of head, mid-piece and tail. There was no acrosome at the anterior end of the nuclears, whereas there was a vesicle. The results revealed that there existed obviously ploymorphic in the sperm of F2 hybrids. In the water-like semen from males of F2 hybrids, different sizes of the head of the sperm including haploid, diploid, tetraploid, and aneuploid sperm were observed. The head diameter of the smallest sperm was only 1.32 microm, but that of the biggest one was about 18.39 microm, and most of them varied from 1.85 to 2.15 microm. The haploid sperm was normal, while the a-neuploid, diploid, tetraploid and multiploid sperm were abnormal. Among the abnormal sperm, there was a super sperm with about 20 tails, whose head volume was much bigger than that of any other sperm. From the results of the transmission electron microscope, 3 sperm with two nucleus and 1 sperm with two tails were found. This study provided an useful evidence for the mechanism that the formation of tetraploid in F3 hybrids was due to the fertilization of the diploid eggs and diploid sperm produced by F2 hybrids.

Animals↗

PubMed2004

[The analysis of genetic variability of mtDNA 12S rRNA genes in the allotetraploid, triploid crucian carp and their parents].

The complete 12S rRNA genes from the five F11 allotetraploids, two diploid gynogens, two triploid crucian carps, one red crucian carp, one xiangjiang common carp, and one Japanese crucian carp were successfully cloned and sequenced. Sequence compositions and variations were analyzed with MEGA 1.0 software. Five F11 allotetraploids shared two haplotypes, and two diploid gynogens, two triploid crucian carps, one red crucian carp, one xiangjiang common carp, one Japanese crucian carp shared one haplotype, respectively. The similarities among red crucian carp, xiangjiang common carp, allotetraploid, diploid gynogen, Japanese crucian carp, and triploid crucian carp varied from 95% to 99%. The similarities between allotetraploid, triploid crucian carp and their female parents (red crucian carp and Japanese crucian carp, respectively) were higher than those between allotetraploid, triploid crucian carp and their male parents (xiangjiang common carp and allotetraploid, respectively). Such result indicated that mitochondrial 12S rRNA genes of the allotetraploid and triploid crucian carp were inherited maternally. A phylogenetic tree was reconstructed using the neighbor joining method of the MEGA package. It was noticeable that after nine generations from F3 to F11 hybrids, the five F11 allotetraploids shared two haplotypes (AT-1 and AT-2), indicating the allotetraploid stock had the genetic diversity. The results provided some valuable information for the breeding, genetic conservation, and population rejuvenation of the tetraploid stock.

Animals↗

PubMed2003

Functional expression and characterization of an acidic actinoporin from sea anemone Sagartia rosea.

Src I is the first reported acidic actinoporin from sea anemone Sagartia rosea with a pI value of 4.8 and comprises 13.9% alpha-helix, 65.1% beta-sheet, and 18.2% random coil. For structure-function studies, Src I was expressed in Escherichia coli as a cleavable fusion protein. Recombinant Src I exhibited obviously hemolytic activity, but the fusion protein Trx-Src I almost lost its hemolytic activity, suggesting the importance of the N-terminal amphiphilic alpha-helix for its functional activity. The cytotoxic effects of Src I depending on the toxin concentration and incubation time were also observed on cultured cells. Among five cell lines: NIH/3T3, U251, NSCLC, BEL-7402, and BGC-823, NSCLC was the most sensitive cells with ID(50) 2.8 microg/ml and BGC-823 was the least sensitive cells with ID(50) 7.4 microg/ml. After incubated with lipid SUVs, such as SM-SUVs and SM/PC-SUVs, the hemolytic activity of Src I was inhibited to some extent. When incubated with calcein-entrapped lipid LUVs, such as SM-LUVs, SM/PC-LUVs, and SM/PG-LUVs, Src I induced release of entrapped calcein. According to the interaction with lipid vesicles, we proposed that it was the membrane matrix made up of phospholipids, not a particular phospholipid that facilitates Src I to react properly.

Amino Acid Sequence↗

PubMed2003

Activation of c-Myc contributes to bovine papillomavirus type 1 E7-induced cell proliferation.

Inactivation of the tumor suppressor pRB by the human papillomavirus (HPV) oncoprotein E7 is a mechanism by which HPV promotes cell growth. The bovine papillomavirus type 1 (BPV-1) E7 does not bind pRB efficiently yet is required for full transformation of murine cells by BPV-1. In the present study, we investigated the mechanism of BPV-1 E7-induced cell proliferation. Our studies indicate that expression of BPV-1 E7 induces DNA synthesis and stimulates cells to enter S phase in quiescent cells. The induction of cell proliferation by BPV-1 E7 can occur in the retinoblastoma gene (Rb)-null cells, suggesting an Rb-independent mechanism. Consistent with this observation, BPV-1 E7 does not efficiently activate the transcription of the E2F family of transcription factors (E2F)-responsive promoters. Notably, c-Myc is able to induce cells to enter S phase in quiescent cells through an Rb/E2F-independent pathway. Significantly, c-Myc levels are increased in BPV-1 E7-expressing cells. Moreover, expression of a dominant negative c-Myc mutant inhibited BPV-1 E7-induced DNA synthesis. Consistent with the notion that c-Myc could down-regulate p27 and activate Cdk2, p27 level is decreased while both cyclin A and cyclin E-associated kinase activities are up-regulated in BPV-1 E7-expressing cells. These studies indicate an important role for c-Myc in BPV-1 E7-induced cell proliferation.

Animals↗

PubMed2003

Neuregulin-1 suppresses muscarinic receptor expression and acetylcholine-activated muscarinic K+ channels in cardiac myocytes.

The neuregulin-1 family of growth factors regulates nicotinic acetylcholine receptor synthesis in skeletal muscle, but its role in cardiac myogenesis remains unclear. Here, we investigate the involvement of neuregulins in the development of cardiac cholinergic responsiveness. Treatment of chick cardiac myocytes with neuregulin-1 inhibited mRNA expression of the M4 muscarinic receptor, but not the M2 receptor. In addition, mRNA levels of GIRK1 were reduced in myocytes by treatment with neuregulin-1. Activation of cholinergic receptors in cultured chick atrial myocytes by carbachol produced an outward potassium current (I(K(ACh))), which was attenuated by 24-48-h pre-treatment with neuregulin-1. These data suggest that neuregulins can regulate cardiac parasympathetic tone and may be involved in the pathogenesis of cardiac arrhythmias and heart failure.

Acetylcholine↗

PubMed2003

Sigma receptors: potential medications development target for anti-cocaine agents.

The ability of cocaine to interact with sigma receptors suggests a viable target for medications development. Recently, numerous novel compounds and antisense oligodeoxynucleotides targeting sigma receptors have been synthesized and shown to prevent the behavioral toxicity and psychomotor stimulant effects of cocaine in animals. Protective doses of sigma receptor antagonists have also been shown to prevent changes in gene expression that are induced by cocaine. Together, the studies provide insight and promising future directions for the development of potential medications for the treatment of cocaine addiction and overdose.

Animals↗

PubMed2003

Adsorption of cations onto the surfaces of silver nanoparticles.

The effects of cations on the absorption spectra of silver sols have been investigated by the UV-vis spectrometry and TEM. Experiments showed that injection of certain amounts of transition metal cations into silver sols resulted not only in the aggregation of silver nanoparticles but also in the appearance of a new band centered near 510 nm in the absorption spectra of silver sols. However, the new band was not observed in the presence of alkaline earth metal cations or the Mv2+ cations. The peak position of the new band depends on the nature as well as the concentration of metal cations used. Comparing the peak positions of the new bands, it was found that the new band induced by the injection of Cr3+ was red-shifted with respect to those induced by Cu2+, Zn2+, or the Cd2+ cations. It is reasonable that this band near 510 nm should be attributed to the coeffects of the adsorption of metal cations onto the surfaces of silver nanoparticles and the aggregation of silver nanoparticles.

Journal Article↗

PubMed2003

Studies of short-wavelength collective molecular motions in lipid bilayers using high resolution inelastic X-ray scattering.

We summarize a series of experimental results made with the newly developed high resolution X-ray scattering (IXS) instrument on two pure lipid bilayers, including dimyristoylphosphatidylcholine (DMPC) and dilauroylphosphatidylcholine (DLPC) in both gel and liquid crystal phases, and lipid bilayers containing cholesterol. By analyzing the IXS data based on the generalized three effective eigenmode model (GTEE), we obtain dispersion relations of the high frequency density oscillations (phonons) of lipid molecules in these bilayers. We then compare the dispersion relations of pure lipid bilayers of different chain lengths among themselves and the dispersion relations of pure lipid bilayers with those of the cholesterol containing bilayers. We also compare our experimental results with collective dynamics data generated by computer molecular dynamics (MD) simulations for dipalmitoylphosphatidylcholine (DPPC) in gel phase and DMPC in liquid crystal phase.

Equipment Design↗

PubMed2003

Regional citrate anticoagulation in critically ill patients during continuous blood purification.

OBJECTIVES: To evaluate the safety and define the contraindication of regional citrate anticoagulation treatment on various critically ill patients being treated by continuous blood purification, who also had bleeding tendencies. METHODS: Forty critically ill patients being treated by continuous blood purification (CBP) were involved in this study. Due to their bleeding tendencies, regional citrate anticoagulation treatment was given to all of them. Those with hepatic function impairment (n = 10) were classified as Group A, those with hypoxemia were classified as Group B (n = 10), and the others as Group C (n = 20). Blood samples were collected before treatment, and at 4, 12, 24, 36, and 48 hour intervals during CBP. These samples then were used arterial blood gas analysis, whole blood activated clotting time (WBACT) pre- and post-filter, and serum ionized calcium examination. RESULTS: WBACT pre-filter showed little fluctuant through the 48 hr period of CBP, and WBACT post-filter showed obvious prolongation than that of the pre-filter (P < 0.05) at all time points. Metabolic acidosis was found in Group A patients before CBP, and improved during CBP. Normal acid-base conditions of patients were disturbed and deteriorated in Group B during CBP, but not in Group C. Serum ionized calcium was maintained at a normal range during CBP in Group A and C patients, but declined significantly in Group B patients (vs. pre-treatment, P < 0.05). CONCLUSIONS: Regional citrate anticoagulation can be safely used in conjunction with CBP treatment for patients with hepatic function impairment, but may induce acidosis and a decline in serum ionized calcium when used with hypoxemic patients.

Adult↗

PubMed2003

Iptkalim inhibits cocaine challenge-induced enhancement of dopamine levels in nucleus accumbens and striatum of rats by up-regulating Kir6.1 and Kir6.2 mRNA expression.

AIM: To investigate the effect and mechanism of novel ATP-sensitive potassium channel opener (KCO) iptkalim (IPT) on acute and cocaine challenge-induced alterations in the levels of dopamine (DA) and glutamate (Glu) from nucleus accumbens (NAc), striatum, and prefrontal cortex (PFC) in rats. METHODS: The levels of DA and Glu were assayed using high performance liquid chromatography (HPLC) combined with amperometric and fluorescent detection, respectively. The mRNA levels of Kir6.1, Kir6.2, SUR1, and SUR2 were measured by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). RESULTS: IPT did not affect acute cocaine (30 mg/kg, ip)-induced elevations in either DA levels from NAc and striatum or Glu levels from NAc and PFC. An acute cocaine challenge (30 mg/kg, ip) on d 21 after withdrawal caused an elevation in DA levels in NAc and striatum. Moreover, the same treatment also increased Glu levels in PFC and NAc of cocaine-pretreated rats. Repeated IPT injections reversed cocaine challenge-induced DA increase in NAc and striatum. Cocaine challenge increased Kir6.1 and Kir6.2 mRNA expression in striatum and NAc and only elevate Kir6.2 expression in PFC in both cocaine-pretreated rats and rats pretreated with IPT plus cocaine. Moreover, expression of Kir6.1 and Kir6.2 mRNA was augmented in rats pretreated with IPT plus cocaine compared to rats pretreated with cocaine alone. No significant change was found in the SUR1 and SUR2 expression of all four groups. CONCLUSION: IPT inhibited cocaine challenge-induced enhancement of DA levels in NAc and striatum by up-regulating Kir6.1 and Kir6.2 mRNA expression.

Animals↗

PubMed2003

Continuous veno venous hemofiltration in treatment of acute necrotizing pancreatitis.

OBJECTIVE: To investigate the effectiveness of using continuous veno venous hemofiltration (CVVH) in the treatment of acute necrotizing pancreatitis (ANP). METHODS: Thirteen ANP patients were involved in this study, including 4 females and 9 males, averaging 50.6 +/- 10.8 years old. CT scans upon admission revealed 33% necrosis involving the body of the pancreas in 2 patients, 67% necrosis in 3 patients and 100% necrosis in the other 8; the CT severity score was 8.9 +/- 2.1. CVVH was maintained for at least 72 hours and the AN69 hemofilter (1.2 m(2)) was changed every 24 hours. The ultrafiltration rate during CVVH was 2993.9 +/- 983.0 ml/h, the blood flow rate was 250 - 300 ml/min, and the substitute fluid was infused in a pre-diluted manner. Low molecular weight heparin was used as anticoagulant. RESULTS: CVVH was well tolerated in all the patients. Bloody abdominal cavity drainage fluid was observed in 2 patients, but no other side-effects related with CVVH were observed. Two patients died of systemic fungal infections and another died of intracranial fungi infection, resulting in an ICU mortality of 23.1%. Ten of the patients survived in the ICU, but one of them died for other reasons unrelated to the SAP before discharge. The APACHE II score before CVVH was 15.2 +/- 6.5, but decreased significantly to 8.1 +/- 5.3, 7.5 +/- 4.9 and 8.0 +/- 5.2 at the 24th, 48th and 72nd hour after CVVH, respectively (P < 0.01). Serum concentration of IL-1beta and TNFalpha decreased to the trough at the 6th hour after a new hemofilter was used and increased slowly to pre-CVVH levels 12 hours later. After CVVH had ceased, the serum levels of two cytokines increased to their peaks at the 120th hour and decreased eventually at the 144th hour. The sieving coefficient (SC) of IL-1beta and TNFalpha was 0.33 +/- 0.11 and 0.16 +/- 0.08. CONCLUSION: CVVH offered therapeutic options for ANP and was well tolerated resulting in clearance of IL-1beta and TNFalpha; CVVH at early stages of SAP may contribute to the improvement of outcome.

Adult↗

PubMed2003

[Expression of E-cadherin in human embryo].

OBJECTIVE: To investigate the role of calcium dependent adhesion molecules (cadherin) during the implantation and development of human embryo by studying the expression of E-cadherin in human embryo and blastocysts. METHODS: Expression of E-cadherin in preimplantation embryos and blastocysts was detected by indirect immunofluorescence assay and quantitated by laser scanning confocal microscopy. RESULTS: Expression of E-cadherin was found in all the preimplantation embryos and blastocysts the present authors studied. The expression was higher in blastocysts than that in preimplantation embryos. CONCLUSION: The above results suggested that human embryos and blastocysts could express E-cadherin and the expression increased during their development. These may be of significance to the adhesion and implantation of the human embryo and blastocysts.

Blastocyst↗

PubMed2003

[The chromosome number and gonadal structure of F9-F11 allotetraploid crucian-carp].

In this paper, the chromosome number of F9-F11 hybridis of Red crucian (Carassius auratus) x common carp(Cryprinus carpio) was examined by means of kidney cell-PHA culture. The results showed that F9-F11 allotetraploids possessed 200 chromosomes, with the karyotype formula 44 m + 68 sm + 44 st + 44 t, which were the same as the data indicated in F3-F8 allotetraploids. Both female and male of F9-F11 allotetraploids had the normal ovaries and testes that were able to produce the normal dipoid ova and sperm. In nature conditions, without the injection of the extraneous hormone, the females and males of F9-F11 allotetraploids mated each other to produce new generation of tetraploids. With the stable genetic tetraploidy and the fertility in the nature environments, this allotetraploid population presented the key factors to form a new species with 200 chromosomes.

Animals↗

PubMed2003

[Acoustic analysis in different background of hearing].

OBJECTIVE: To find out the changes of voice in different noisy background by computer acoustic analysis. METHOD: Twenty-five young people who got normal hearing level and normal vocal cords were selected. They were tested after trained. Sustained /a/,/i/ and sentences were recorded in the three different background: quite, white band noise and speech noise. The software of MDVP was used. Testing parameters included: F0, Jitter, Shimmer, APQ, PPQ, HNR. RESULT: Fundamental frequencies of noisy groups are significantly higher in male-/a/, female-/a/ and female-/i/ groups. The perturbations are not significantly different among them. The HNR is negatively relative with F0. CONCLUSION: Normal hearing persons increase their fundamental frequencies in the noisy surroundings.

Adult↗

PubMed2003

[Continuous veno-venous hemofiltration in treatment of acute severe hyponatremia: a report of 6 cases].

OBJECTIVE: To investigate the effect of continuous veno-venous hemofiltration (CVVH) in the treatment of acute severe hyponatremia. METHODS: Six patients with acute severe hyponatremia were studied, including 5 males and 1 female, aged 48.5 (25 - 61) years. Clinical manifestations of hyponatremia included confusion (6/6), drowsiness (3/6), and delirium (3/6). The course of hyponatremia before the initiation of CVVH was 45 - 48 hours. AN69, AV600, FH66 and HF1200 hemofilters were applied and changed every 24 hours. The ultrafiltration rate was 2 000 ml/h, with a blood flow rate of 200 - 250 ml/min, and the substitute fluid was infused by a pre-dilution route. Low molecular weight heparin was used for anticoagulation. RESULTS: The average treatment duration of CVVH was 59.7 (45.6 - 86) hours. All the patients survived and tolerated CVVH well. During CVVH, the serum sodium increased significantly from (101.2 +/- 4.2) mmol/L before CVVH, to (115.0 +/- 2.7) mmol/L at the 6th hour of CVVH, (129.2 +/- 4.1) mmol/L at the 24th hour, and (140.3 +/- 1.6) mmol/L at the 48th hour of CVVH; with the correction rate of serum sodium controlled at (2.5 +/- 0.4) mmol.L(-1).h(-1) over the first 24 hours, (1.2 +/- 0.1) mmol.L(-1).h(-1) for the first 48th hour, and the correction rate of (0.82 +/- 0.10) mmol.L(-1).h(-1). The sodium concentrations in the replacement solution were (16.0 +/- 6.0) mmol/L higher than the serum sodium concentration at 0 hour, (11.6 +/- 4.3) mmol/L higher at 4th hour, (5.5 +/- 5.1) mmol/L higher at 24th hour, and (0.75 +/- 0.96) mmol/L higher at 48th hour of CVVH. After CVVH, the serum osmolarity increased significantly, from (216.7 +/- 7.4) mOsm/kgH(2)O pre-CVVH, to (245.0 +/- 5.5) mOsm/kgH(2)O at 6th hour, with a correction rate of (5.16 +/- 0.81) mOsm.kgH(2)O(-1).h(-1); (272.7 +/- 7.1) mOsm/kgH(2)O at 24th hour, with a correction rate of (2.33 +/- 0.28) mOsm.kgH(2)O(-1).h(-1); and (295.0 +/- 4.2) mOsm/kgH(2)O at 48th hour, with a correction rate of (1.63 +/- 0.20) mOsm.kgH(2)O(-1).h(-1). The Glasgow scores and APACHEII scores improved significantly as compared to pretreatment. CONCLUSION: CVVH is effective in the treatment of acute severe hyponatremia, and could be considered as a treatment option because of its slow and continuous nature. A low-sodium replacement solution should be prepared to minimize its sodium concentration difference from the serum concentration. We recommend that the serum sodium concentration be corrected at an average rate of (2.50 +/- 0.14) mmol.L(-1).h(-1) at 6 h, (1.2 +/- 0.1) mmol.L(-1).h(-1) at 24 h and (0.82 +/- 0.10) mmol.L(-1).h(-1) at 48 h.

Acute Disease↗

PubMed2003

A karyometric approach to the characterization of atypical endometrial hyperplasia with and without co-occurring adenocarcinoma.

OBJECTIVE: To develop a karyometric image analysis approach to distinguishing atypical endometrial hyperplasia with and without co-occurring adenocarcinoma. STUDY DESIGN: Six cases of atypical hyperplasia without and 6 cases with co-occurring adenocarcinoma, 4 cases of normal endometrium and 3 cases of adenocarcinoma were identified. From each case 100 nuclei were measured in representative diagnostic areas identified by an experienced pathologist. Discriminant analyses were performed. An unsupervised learning algorithm was applied to define and characterize different nuclear phenotypes, and those data were used to identify cases with co-occurring adenocarcinoma. RESULTS: Discriminant analysis showed that nuclei from atypical hyperplasia and atypical hyperplasia with co-occurring adenocarcinoma are statistically different. The unsupervised learning algorithm revealed differences in nuclear subpopulations that can be used to correctly identify an estimated 85% of individual cases. CONCLUSION: Nuclei from atypical hyperplasia without and with co-occurring adenocarcinoma have statistically different karyometric characteristics that may facilitate case classification.

Adenocarcinoma↗

PubMed2003

Karyometry of nuclei from actinic keratosis and squamous cell cancer of the skin.

OBJECTIVE: To use karyometric analysis methods to compare actinic keratoses (AKs) to squamous cell carcinomas (SCCs) to determine if SCCs showed a logical progression beyond that seen in AKs and to explore variability within and between lesion types to better understand distinctions between the 2. STUDY DESIGN: Biopsies from 31 subjects with AKs were obtained from upper inner arm skin, forearm skin and AK lesions. Biopsies from 23 different subjects in a related subproject provided SCC biopsies for comparison. RESULTS: Karyometric measures of nuclear abnormality and sun damage were derived. Mean actinic damage levels progressed logically from inner arm to sun-exposed skin, to AK, to SCC. Considerable heterogeneity existed at the case level. Unsupervised learning methods revealed 2 distinct clusters of progressed lesions with different nuclear signatures, reflecting differing levels of actinic damage. Number of AKs and SCCs and invasiveness and differentiation of SCCs were distributed across both clusters in roughly equivalent proportions. CONCLUSION: Karyometric methods, shown previously to be capable of sensitively detecting subtle nuclear changes, revealed the possibility of 2 progression pathways, each containing AKs and SCCs. This finding may have prognostic implications.

Adolescent↗

PubMed2003

[Effects of extremely low frequency electromagnetic fields on the level of c-fos mRNA in brain and liver of mouse].

OBJECTIVE: To study the effects of extremely low frequency electromagnetic fields (ELF EMFs) on c-fos gene expression in mouse brain and liver tissues. METHODS: Mice were exposed to 50 Hz sinusoidal 0.2 mT or 6.0 mT electromagnetic field for 2 weeks or 4 weeks. Competitive RT-PCR method was used to measure c-fos mRNA level. RESULTS: After exposure to 0.2 mT or 6.0 mT field for 2 weeks, c-fos mRNA levels in brain tissue [(0.0178 +/- 0.0076) amol/120 ng cDNA and (0.0092 +/- 0.0042) amol/120 ng cDNA respectively] were higher than that of control level [(0.0012 +/- 0.0005) amol/120 ng cDNA] (P < 0.05). In liver tissue c-fos mRNA levels [(0.0117 +/- 0.0055) amol/120 ng cDNA and (0.0148 +/- 0.0162) amol/120 ng cDNA respectively] were also higher than that of control level [(0.0005 +/- 0.0005) amol/120 ng cDNA] (P < 0.05). After exposure to 0.2 mT or 6.0 mT field for 4 weeks, c-fos mRNA levels in brain tissue [(0.0100 +/- 0.0054) amol/120 ng cDNA and (0.0198 +/- 0.0079) amol/120 ng cDNA respectively] were higher than that of control level [(0.0015 +/- 0.0008) amol/120 ng cDNA] (P < 0.05). In liver tissue the exposure induced much higher expression level [(0.0173 +/- 0.0122) amol/120 ng cDNA and (0.0133 +/- 0.0090) amol/120 ng cDNA respectively] while no expression was found in the control. CONCLUSION: Exposure to 50 Hz electromagnetic fields may induce up-regulation of c-fos transcription in mouse brain and liver tissue.

Animals↗