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Biomedical subjects

M Liu

Publications and source records attributed to M Liu.

At least 451 records · Page 25Linked to original sources
PubMed1997

Status of the eradication of indigenous wild poliomyelitis in the People's Republic of China.

A large nationwide outbreak occurred in 1989-1990 in China, in which nearly 10,000 poliomyelitis cases were reported. After two rounds of oral poliovirus vaccine (OPV) supplemental activity in nearly every province in the 1992-1993 winter season, no wild poliovirus was detected in 1993 in 22 provinces in the middle of China that contained 86% of the population. During the first national immunization days (NIDs) conducted in December 1993 and January 1994, 83 million children 0-47 months of age were immunized. In 1994, wild poliovirus was identified in only 6 of 2397 children with stool specimens tested. After a second NID in December 1994 and January 1995, no wild poliovirus was detected in 1995 despite a very high level of virus surveillance. In summary, double-round mass supplemental OPV immunizations in children 0-3 years old in two consecutive winters eliminated wild poliovirus from 23% of the world's population (1.2 billion people).

Child, Preschool↗
PubMed1997

Voltage-dependent gating of ATP-activated channels in PC12 cells.

The possibility that P2X receptors exhibit voltage-dependent gating in a similar manner to nicotinic receptors was investigated in rat pheochromocytoma cells with the use of whole cell voltage-clamp techniques. In the presence of extracellular ATP, slowly activating inward currents were elicited by stepping from -50 mV to potentials more negative than -80 mV; these currents had a time constant of approximately 60 ms at -120 mV. This slowly activating component (as a fraction of the total ATP-induced current) increased with membrane hyperpolarization from -80 to -100 mV and was much increased when depolarizing prepulses were applied, although the time constant of activation was not altered by depolarizations. The fraction of the slowly activating current and its time constant were decreased as the ATP concentration was increased from 10 to 300 microM. Thus it has been demonstrated that voltage-dependent gating of ATP-activated channels does occur in PC12 cells, and that this gating is modified by agonist concentration. It is possible that such gating may serve as a postsynaptic mechanism to facilitate excitatory neurotransmission by contributing to the inward rectification of the ATP-activated currents.

Adenosine Triphosphate↗
PubMed1997

Cholesterol enhances platelet-derived growth factor-BB-induced [Ca2+]i and DNA synthesis in rat aortic smooth muscle cells.

In the present study, we describe possible mechanisms by which hypercholesterolemia may contribute to the development of cardiovascular diseases. Treatment of rat aortic smooth muscle cells for 20 hours with cholesterol-rich liposomes (500 micrograms/mL cholesterol, 100 micrograms/mL low-density lipoprotein) resulted in a 76 +/- 12% increase in total cholesterol content. The effects of cholesterol enrichment were examined by determination of changes in cell membrane fluidity. Fluidity of the cholesterol-enriched cell membranes was decreased at all temperatures between 15 degrees C and 40 degrees C. Changes in membrane fluidity in whole cell membranes represented changes in fluidity of microsomal membranes isolated by Percoll gradient ultracentrifugation. The basal [Ca2+]i and the maximal platelet-derived growth factor (PDGF)-BB-induced [Ca2+]i was elevated by 30% and 90% in cholesterol-enriched cells, respectively. In contrast, the resting pH, and the PDGF-BB-induced stimulation of the Na+/H+ exchange were not affected in cholesterol-enriched cells. The effect of PDGF-BB on [3H]thymidine incorporation in cholesterol-enriched cells was elevated by 40% in comparison with untreated cells. Our findings show that cellular cholesterol may be involved in the development of vascular diseases via modulation of the PDGF-induced increase in [Ca2+]i and DNA synthesis in vascular smooth muscle cells.

Animals↗
PubMed1997

[The protective effect of SOD on injury of bone marrow hematopoietic progenitor cells of mice under 4 degrees C storage].

The protective effect of Cu, Zn, SOD on bone marrow hematopoietic progenitor cells of mice, under 4 degrees C storage was studied. The results showed, if 1.65 U or 0.165 U/ml SOD was added to the cell suspension for 3 days at 4 degrees C, the production rate of CFU-GM, CFU-E, BFU-E, CFU-Meg and CFU-Mix were 6.2, 2.6, 2.9, 4.0 and 5.1 times that of control group (without SOD) respectively. The survival rate of hematopoietic progenitor cells increased obviously. The mechanism of SOD effect is supposed to prevent hematopoietic progenitor cells from death, instead of the regulating proliferation. It may be closely related to the antioxidation of SOD which scavenges the superoxide free radicals.

Animals↗
PubMed1997

[A study of 46 forensic autopsy cases of medical tangle].

Forty-six forensic autopsy cases of medical tangle were investigated for understanding the characteristic of medical tangle cases and for comparing the consistency between clinical and pathological diagnoses. The age ranged from 6 days to 68 years. Women outnumbered men by ratio of 1.3:1. The most common occupation was farming. The consistency between clinical and pathological diagnoses was 34.78%. The causes of medical tangle and the difference between clinical and pathological diagnoses were discussed.

Adolescent↗
PubMed1997

[A primary study on antagonizing effects of anti-snake venom Chinese herbs on endothelin-1 and sarafotoxin 6b].

Some anti-snake venom Chinese herbs were used to test the antagonizing effect on ET-1 and S6b. Oral administration has shown that both the water and alcohol extracts from Cissus assamica and Aristolochia fordiana, and the water extracts from Desmodium microphyllum, Cynanthum paniculatum and Polygonum cillinerve are very helpful in reducing the acute death caused by ET-1 and S6b(i.v.), while the extracts from Cissus assamica, Aristolochia fordiana and Cynanthum paniculatum can dilate the vasoconstriction by ET-1 in a dose dependent manner. Pharmacodynamic parameters have shown that the potencies of alcohol extracts from Cissus assamica and Aristolochia fordiana are greater than that of Cynanthum paniculatum. These data suggest that traditional anti-snake venom herbs have antagonizing effects on ET-1.

Animals↗
PubMed1997

[Establishment of semi-nested polymerase chain reaction for detecting Coxsackie B virus RNA and the application in clinical diagnosis of viral myocarditis].

The aim of this study was to determine the applicability of the polymerase chain reaction (PCR) technique for the detection of CBV RNA and for routine diagnostic use in clinics. To this end, three oligomeric regions of great homology among the CBVs were selected from the conserved 5'-noncoding region of the CBV genome, and were designated as a set of primers and probe. Semi-nested CBV PCR assay was established. The sensitivity of the method is at 0.1 TCID50 in diluted virus stocks, and this method doesn't react with other related viruses. After the optimum reaction system was determined, the technique was then used in clinical samples. In patients with myocarditis, 62 of 111 serum samples were positive by PCR. The CSF samples from patients with meningitis were also tested, and the positive result was found in 7 out of 20 (35%) specimens. Using the same 111 samples, the PCR technique was compared with the ELISA. The detection rates of the two methods for CBV were 56% and 45%, respectively, with a coincident rate of 77%.

Enterovirus B, Human↗
PubMed1997

[Detection of bcr gene rearrangement in chronic myeloid leukemia by fluorescence in situ hybridization].

OBJECTIVE: To detect bcr gene rearrangement in chronic myeloid leukemia (CML). METHODS: Bcr rearrangement was detected by fluorescence in situ hybridization (FISH), using 765E3, a yeast artificial chromosome (YAC)-derived probe flanking the breakpoint within bcr gene. RESULTS: Nine patients with CML were examined, bcr gene rearrangement was revealed in 5 cases in chronic phase, 2 in blastic phase, and one after interferon-alpha therapy. The karyotype of 1 case after autologous bone marrow transplantation (ABMT) was chimera with normal and bcr gene rearrangement chromosomes. CONCLUSION: YAC765E3 is a useful probe for detecting bcr gene rearrangement. FISH technique is likely an important tool for monitoring of treatment and revealing minimal residual disease in CML.

Chromosomes, Artificial, Yeast↗
PubMed1997

Evaluation of proliferating cell nuclear antigen (PCNA) in supraglottic carcinoma.

It is widely accepted that tumor invasion and metastasis are the primary causes for the lethal clinical outcome of cancers. In recent years, attention has been drawn to PCNA (Proliferating Cell Nuclear Antigen) to predict the prognosis of some cancers. In the present paper, we have studied anti-PCNA antibody PC10 in supraglottic cancer by means of immunohistochemistry using paraffin-embedded sections, to demonstrate its clinical significance in this type of malignancy. Twenty-two patients with supraglottic cancer, including T1 (5 cases), T2 (13 cases) and T4 (4 cases) with N- (14 cases) and N+ (8 cases), were investigated for the PCNA expression. The percentages of PCNA positive cells were divided into three groups: < 25%, 25-75%, > 75%, with the range from 10.6 to 95.2%. Results showed that PCNA was well correlated with lymph node metastasis, and appeared to have an inverse correlation with histopathological grades. In this small group, we did not find that PCNA was correlated with T stages and tumor size. However, compared with other T-stages and tumor sizes, the correlation between lymph node metastasis and PCNA seemed to have more clinical significance in T2-stage and in tumors larger than 2 cm. PCNA could be used as a marker in predicting the clinical outcome in supraglottic cancers. An analysis on a large scale is anticipated.

Adult↗
PubMed1997

[Experimental study of the effect of motion on repairing defect of articular cartilage following autogenous periosteal graft].

In order to investigate the effect of motion on repairing articular cartilage defect following autogenous periosteal graft, sixty adult rabbits were divided randomly into three groups: out-cage motion (OCM), in-cage motion (ICM) and immobilization (IMM). A defect of the articular cartilage, 1 cm x 0.5 cm in size, was made in the patellar-groove of femur of each hind limb. Free autogenous periosteal graft from the proximal tibia was sutured on the base of the left defect, while the right limb was served as control. The animals were sacrificed at 4, 8 and 12 weeks, respectively, after operation. The regeneration of the cartilage implanted was observed through gross, histology, histochemical assay and electronic microscope. The influence of different amount of motion on the chondrogenesis from the periosteal implant was also compared. The result showed that the hyaline cartilage produced from periosteal implant could be capable to repair full-thickness of articular cartilage. From statistical study, there was significant difference between OCM and ICM groups (P < 0.05), ICM and IMM (P < 0.05) as well as OCM and IMM (P < 0.01). It was suggested that the periosteal graft was effective in repair of defect of articular cartilage and the amount of motion was important for chondrogenesis.

Animals↗
PubMed1997

[Color Doppler flow imaging study on the changes of collateral circulation between portal-superior vena cava and azygos vein before and after endoscopic ligation of the esophageal varix].

Color Doppler flow imaging (CDFI) was performed in 35 patients with portal hypertension and esophageal varix. Thirty subjects were served as control. After esophageal variceal ligation, CDFI observed that the portal-superior vena cava collateral veins were partialy blocked. The esophageal varices disappeared. The esophageal wall thinned. Diameter of left gastric vein enlarged and blood flow velocity decreased. Azygos diameter was reduced and blood flow velocity was decreased. Although diameter of portal vein was not changed, the blood flow velocity slightly increased. The results suggest that ligation treatment can have the tendency to increase blood flow of liver and stomach, which might aggravate gastric mucosal lesion.

Adolescent↗
PubMed1997

[The sonarographic diagnosis of prostatic and periprostatic cysts on high resolution transrectal ultrasound imaging].

The symptoms of prostatic and periprostatic cysts are nonspecific and digital rectal examination has no definite findings detected. The conventional radiological plain film cannot define the relationship of a cyst to the surrounding structures. The use of MRI as a means in detection is too expensive. To solve these problems, we detected 118 cysts in 73 patients by transrectal ultrasound (TRUS) and discussed the TRUS imaging findings of various prostate and periprostate cysts with illustrations from our clinical practice. We suggest that TRUS can be used routinely, because its distinct advantage of high resolution for minute nodular or cystic lesion detection with high quality image demonstrates the relationship of surrounding structures, and provides an outstanding novel diagnostic modality.

Adult↗
PubMed1996

Transcriptional activation of the human p21(WAF1/CIP1) gene by retinoic acid receptor. Correlation with retinoid induction of U937 cell differentiation.

We reported previously that the induced differentiation of the myelomonocytic cell line U937 by vitamin D3 is facilitated by the transcriptional induction of the p21(WAF1/CIP1) gene by the vitamin D3 receptor (Liu, M., Lee, M.-H., Cohen, M., and Freedman, L. P. (1996) Genes Dev. 10, 143-153). Retinoic acid (RA), a physiological metabolite of vitamin A, is also a potent inducer of differentiation of several cell types, including myeloid leukemic cells. Like vitamin D3, RA acts through a subfamily of nuclear hormone receptors, RARs and RXRs (retinoid X receptors), which regulate the expression of target genes by binding to specific DNA elements and modulating transcription initiation. In this report we demonstrate that the gene encoding p21 is also a RA-responsive target gene, and we describe a functional RA response element in this gene's promoter which is required to confer RA induction through RAR.RXR heterodimers. These results correlate the RA induction of monocytic differentiation of U937 cells with the transcriptional activation of the p21 gene and suggest a role for this cyclin/cyclin-dependent kinase complex inhibitor in facilitating this differentiation pathway.

Cell Differentiation↗
PubMed1996

Immunization with plasmid DNA encoding for the measles virus hemagglutinin and nucleoprotein leads to humoral and cell-mediated immunity.

We have evaluated the DNA vaccination strategy for measles virus (MV) hemagglutinin (HA) and nucleoprotein (NP) genes. Plasmids encoding either the MV, HA, or NP proteins inoculated intramuscularly into Balb/c mice induced both humoral and CTL class I restricted responses. Antibody responses were not increased by multiple inoculations. The major antibody isotype induced by both the HA and NP was IgG2a consistent with a Th1 response. In contrast, immunization with a plasmid which directed the synthesis of a partially secreted form of HA gave mainly IgG1 antibodies. When the amount of DNA was reduced for the HA plasmid (1 or 10 microg/animal), although the antibody was not induced, a CTL response was observed.

Animals↗
PubMed1996

The sympathetic nervous system contributes to capsaicin-evoked mechanical allodynia but not pinprick hyperalgesia in humans.

The contribution of the sympathetic nervous system (SNS) to pain, mechanical allodynia (MA), and hyperalgesia in humans is controversial. A clearer understanding is crucial to guide therapeutic use of sympatholytic surgery, blocks, and drug treatments. In rats, capsaicin-evoked MA, and to some extent, pinprick hyperalgesia (PPH), can be blocked with alpha-adrenoreceptor antagonists. In this study, we examined the contribution of the SNS to MA and PPH in normal human subjects by blocking alpha-adrenoreceptors with intravenous phentolamine. In a double-blinded, placebo-controlled, crossover study, subjects were given IV saline or phentolamine, 1 mg/kg over 20 min. Ten minutes after the start of the infusion, subjects received 100 micrograms of intradermal capsaicin on the foot dorsum with the temperature of the injected site clamped at 36 degrees C. The temperature of the uninjected foot was used to monitor the degree of alpha-adrenoreceptor blockade produced by phentolamine. Ongoing pain and MA and PPH areas were measured every 5 min for 60 min. A significantly greater increase in temperature on the uninjected foot was seen during the phentolamine infusion compared with the saline infusion, indicating alpha-adrenergic blockade. Significantly less MA was observed with the phentolamine infusion 10-25 min after capsaicin injection than with the saline infusion. No significant differences in ongoing pain or PPH areas were seen between the two infusions at any time. Our results suggest that capsaicin-evoked MA and PPH have different mechanisms, with the SNS having a role in MA but not in PPH or ongoing pain.

Capsaicin↗