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Biomedical subjects

X M Liu

Publications and source records attributed to X M Liu.

At least 55 records · Page 3Linked to original sources

Fixed-duration multidrug therapy in multibacillary leprosy.

Six-hundred-fifty-seven active multibacillary (MB) leprosy patients were put on fixed-duration multidrug therapy (FD-MDT) between 1985 and 1992 (190 had had no and 235 had had previous treatment with dapsone) and were followed for 5 years after therapy. Two relapses occurred during year 5 of surveillance and both had received dapsone prior to chemotherapy, giving an overall relapse rate of 0.08/100 person-years (py). Excluding the two relapses, 99.4% of the MB patients converted to smear negativity at year 6 after a regular course of FD-MDT. The relapse rate for 35 MB patients with an initial bacterial index (BI) of > 4 with 5 years of surveillance was 0.24/100 py. Reactions occurred more frequently during the first 6 months of MDT, decreasing gradually thereafter, and reaching 0 in year 4 of surveillance. The deformity rate at intake was 22.7% and only 1.8% of MB patients developed new deformities or an increased grade in deformity during therapy.

Adolescent↗

Induction of differentiation and down-regulation of c-myb gene expression in ML-1 human myeloblastic leukemia cells by the clinically effective anti-leukemia agent meisoindigo.

Meisoindigo, a second generation derivative of indirubin, is an effective chemotherapeutic agent with very low toxicity used in the treatment of chronic myeloid leukemia. To determine the nature of this activity, the effect of a nontoxic concentration (0.72 micrograms/mL) of this compound on ML-1 human myeloblastic leukemic cells was examined. At such a concentration, differentiation induction was found to be the most pronounced drug effect. During the 3-day drug incubation period, the viable cell number remained essentially constant, with approximately 48% of the cells demonstrating a mature phenotype with increased acid phosphatase activity and nitroblue tetrazolium dye reduction. As observed with other DNA-specific agents, induction of ML-1 differentiation by meisoindigo was accompanied by the down-regulation of c-myb gene expression. These data suggest that induction of leukemic cell differentiation associated with decreased c-myb expression may be one of the mechanisms of the antitumor action of meisoindigo.

Antineoplastic Agents↗

Fourier transform infrared spectroscopy and site-directed isotope labeling as a probe of local secondary structure in the transmembrane domain of phospholamban.

Phospholamban is a 52-amino acid residue membrane protein that regulates Ca(2+)-ATPase activity in the sarcoplasmic reticulum of cardiac muscle cells. The hydrophobic C-terminal 28 amino acid fragment of phospholamban (hPLB) anchors the protein in the membrane and may form part of a Ca(2+)-selective ion channel. We have used polarized attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy along with site-directed isotope labeling to probe the local structure of hPLB. The frequency and dichroism of the amide I and II bands appearing at 1658 cm-1 and 1544 cm-1, respectively, show that dehydrated and hydrated hPLB reconstituted into dimyristoylphosphatidycholine bilayer membranes is predominantly alpha-helical and has a net transmembrane orientation. Specific local secondary structure of hPLB was probed by incorporating 13C at two positions in the protein backbone. A small band seen near 1614 cm-1 is assigned to the amide I mode of the 13C-labeled amide carbonyl group(s). The frequency and dichroism of this band indicate that residues 39 and 46 are alpha-helical, with an axial orientation that is approximately 30 degrees relative to the membrane normal. Upon exposure to 2H2O (D2O), 30% of the peptide amide groups in hPLB undergo a slow deuterium/hydrogen exchange. The remainder of the protein, including the peptide groups of Leu-39 and Leu-42, appear inaccessible to exchange, indicating that most of the hPLB fragment is embedded in the lipid bilayer. By extending spectroscopic characterization of PLB to include hydrated, deuterated as well as site-directed isotope-labeled hPLB films, our results strongly support models of PLB that predict the existence of an alpha-helical hydrophobic region spanning the membrane domain.

Amino Acid Sequence↗

Activation of casein kinase II in ML-1 human myeloblastic leukemia cells requires IGF-1 and transferrin.

Casein kinase II (CK II), a key enzyme involved in the regulation of cell growth, has been variously reported to be activated by diverse mitogens, including insulin-like growth factor 1 (IGF-1) and epidermal growth factor (EGF). Activation of the enzyme is generally carried out in the presence of serum, and we examined the question whether serum components participate in the activation process. We demonstrated previously that ML-1 cells require IGF-1 plus transferrin (TF) for growth and transforming growth factor beta or tumor necrosis factor alpha plus TF for differentiation. We now found that CK II is activated only when the cells are exposed to both IGF-1 and TF or when TF is replaced in this combination with relatively high levels of iron salts. Induction of differentiation with TGF-beta and TF did not result in CK II activation. These results show that CK II activation in ML-1 cells requires the application of both components of the growth signal, IGF-1 and TF, demonstrating that the growth factor alone is incapable of enhancing the activity of the enzyme.

Amino Acid Sequence↗

Analysis of plasma fibrinolysis in the patients with acute cerebral infarction.

In the present study, the plasma fibrinolytic activity in 30 cases of cortical artery territory cerebral infarction (CACI) and 32 cases of perforating artery territory cerebral infarction (PACI) within 3 days after ictus, and 30 sex- and age-matched controls without cardio-cerebrovascular diseases were evaluated by a comprehensive panel of assay, including the plasma tPA activity, PAI activity, endothelial capacity of tPA release and PAI/tPA ratio. The results showed that the plasma fibrinolysis and the endothelial potential to release tPA responding to stimulation in both subtypes of the patients were significantly lower than those in the controls, which provide the theoretical basis for carrying out the thrombolytic therapy in the ischemic stroke. And the study also suggested that increased plasma PAI activity could increase the risk of AS thrombotic events with increased serum triglyceride level.

Acute Disease↗

Regulation of c-myb expression in ML-1 human myeloblastic leukemia cells by c-ets-1 protein.

C-myb and c-ets-1 have variously been demonstrated to function as protooncogenes. Using a human leukemic cell line, ML-1, we have examined the mechanism by which these genes participate in establishing the sustained proliferation mode that is characteristic of the transformed cell. In the absence of serum, ML-1 cells were found to require IGF-1 and transferrin (TF) for growth and TGF-beta or TNF-alpha plus TF for differentiation. Upon administration of the growth factors, c-myb expression increased within 60 min, whereas after addition of the differentiation factors c-myb expression ceased completely within 3 hr. A correlation was found to exist between the level of c-ets-1 protein in the cells, the extent to which that protein is bound to intron I of the myb gene and the amount of c-myb mRNA that is expressed. Upon administration of growth factors, a sizable increase in the intracellular, and particularly, in the intranuclear level of c-ets-1 protein was observed, whereas a pronounced decrease in the level of this protein occurred after exposure to the differentiation factors. These data demonstrated that the level at which an oncogene-specified transcription factor is expressed can affect the expression of other target oncogenes involved in the regulation of cell proliferation. Stimulated expression of such transcription factor can then lead to the continuous proliferation cycle characteristic of the cancer cell.

Blotting, Western↗

[Pharmacokinetics of zinc acexamate (ZAC) in rats].

Zinc acexamate (ZAC) is a new antiulcer drug. This paper reports the pharmacokinetics of ZAC in rats after single oral administration. The concentrations in biological samples were detected by spectrophotometry. This study shows that the concentration-time curve of ZAC in blood conformed to a single-compartment open model after 250, 500 and 750 ng.kg-1 ig. ZAC absorption was fast and the peak plasma level appeared in 1.5 h. The Cmax, AUC and CL/F were shown to be dose dependent. Two hours after oral administration of ZAC to normal rats, the highest level of ZAC was present in the gastrointestinal tract, while appreciable ZAC was present in the kidney, liver, plasma and lung. The level of ZAC in heart, spleen and brain was lower, no drug was detected in muscles and uterus. Six hours after oral administration, the drug concentration in various tissues decreased rapidly, but that of the gastrointestinal decreased very slowly. Feces excretion was an important route of excretion. ZAC excretion was about 11.7% of the administered dosage in feces within 48 h period, and the excreted amount from urine and bile was very small.

Aminocaproates↗

[The effect of IL-1 receptor antagonist on bleomycin-induced pulmonary fibrosis].

Interleukin-1 (IL-1) is a cytokine with diverse biological activities. It can serve as a fibroblast (FB) growth factor which involves in the development of pulmonary fibrosis. IL-1 receptor antagonist (IL-1ra) can compete with IL-1 for occupancy of surface receptors of target cells without agonist effect. In order to find a new method to treat pulmonary fibrosis, we investigated the effect of recombinant human IL-1ra on the development of pulmonary fibrosis by evaluating collagen content, histological change, and TGF-beta mRNA expression in the rats bleomycin-induced pulmonary fibrosis. The results indicate are that there are no significant difference between the IL-1ra treated group and the control group.

Animals↗

[Management of posterior capsule rupture and vitreous loss during IOL implantation].

Among 331 cataract extractions with IOL implantation performed May 1988-Jan. 1992, 33 (10%) were complicated with posterior capsule rupture and vitreous loss occurred in 16 eyes (4.8%). After vitrectomy with scissors and sponge, in-the-bag implantation was performed in 3 eyes, sulcus-fixed lenses in 24 eyes, and anterior chamber lenses in 6 eyes. 32 eyes (97%) gained visual acuity of 0.5 or better during follow-ups of 5 months to 4 years, indicating that with careful anterior vitrectomy and proper modality of IOL implantation, good visual results could be achieved.

Adolescent↗

Differential binding of nuclear c-ets-1 protein to an intron I fragment of the c-myb gene in growth versus differentiation.

For growth, ML-1 human myeloblastic leukemia cells require insulin-like growth factor 1 together with transferrin, whereas for differentiation they depend upon transforming growth factor beta in combination with transferrin. As shown in this study, growth stimulation is accompanied by c-myb expression, whereas initiation of differentiation results in the cessation of c-myb expression through premature termination of transcription in the first intron of the myb gene. Growth factor-stimulated c-myb elongation was found to correlate with an elevated level of nuclear c-ets-1 protein and with increased binding of this protein to an 18-base pair sequence in intron 1 of the c-myb gene containing the putative regulatory element PEA 3. In contrast, differentiation factor-initiated ML-1 cell maturation was accompanied by a very low level of nuclear c-ets-1 protein, by the inability to detect binding of the protein to the 18-base pair sequence, and by the cessation of c-myb expression. These results show a correlation to exist between c-ets-1 binding to intron 1 of the c-myb gene and c-myb expression. The mechanism underlying this correlation is under further study.

Base Sequence↗

Changes of thyroid hormone levels in epileptic patients.

We measured serum T3, T4, FT3, FT4 and thyrotropin (TSH) by radioimmunoassay in 150 patients with epilepsy. Of the 150 epileptic patients, 120 cases received single antiepileptic drug, including Sod valproate (VPA), carbamazepine (CBZ), phenytoin (PHT), or MixtBrodsky (MB). Each subgroup consisted of 30 cases. The other 30 were untreated epileptics. The results suggested that there was no significant difference in serum thyroid hormone levels among healthy control group, untreated group, and hepatic non-enzyme-inducing anticonvulsant group (P < 0.05). As compared with the three groups mentioned above, the serum T3, T4, FT3, FT4 concentrations of the enzyme inducer groups were decreased, however, significant decrease was found in PHT group and CBZ group (P < 0.05, P < 0.005). All 12 patients with circulating thyroid hormone concentrations below normal reference values were given enzyme inducer. None of them revealed any clinical manifestation of hypothyroidism. There was no significant difference in serum TSH level among the above 6 groups (P < 0.05), and the serum TSH level of all patients was within normal reference limits. Our study showed that the changes of thyroid hormone in epileptics were due to the effect of some AEDs and not the disease itself. The disparity between the effect of enzyme inducer and that of non-enzyme-inducing anticonvulsants indicated that the hepatic microsomal enzyme system metabolizing thyroid hormone to be induced was the main mechanism for decreased serum thyroid hormone concentrations. Though the serum thyroid hormone levels of the enzyme inducer groups were decreased, no significant increase of the mean serum TSH concentration was found. This implies that AEDs may interfere the HPA function in some way.

Adult↗

[Comparative studies on the diagnosis of clonorchiasis by IEST and IFAT].

Both immunoenzymatic staining technique (IEST) and indirect fluorescent antibody test. (IFAT) with frozen sections of adult Clonorchis sinensis as antigen were employed for detecting 51 cases with clonorchiasis and 50 healthy persons. The positive rate was 92% with IEST and 88% with IFAT. The results showed no significant statistic difference (P > 0.05). The false positive rates were 2% with the former and 4% with the latter. When sera from 22 cases with acute schistosomiasis, 20 cases with chronic schistosomiasis and 15 cases with paragonimiasis were examined by IEST and IFAT, cross-reactions were 14%, 5% and 0% with IEST, and 14%, 10% and 0% with IFAT, respectively. The results showed that both IEST and IFAT are useful methods for serological diagnosis of clonorchiasis and the antigen on the gut was well demonstrated, while IEST might be more suitable in field surveys.

Animals↗

[Application of cluster analysis to chemical taxonomy of medicinal material maidong].

The cluster analysis shows that the phytochemical constituents in genera Ophiopogon and Liriope are obviously different from each other and even different species of the same genus are not quite similar. Being consistent with the result of the traditional morphological classification, the cluster analysis may provide a chemical evidence for the phytochemical taxonomy and identification of medicinal material Maidong.

Chromatography, Thin Layer↗

Experimental and clinical studies on one-stage arterialization of the venous channels for revascularization of severely ischemic limbs.

A new approach to perfuse arterial blood through venous channels for revascularization of severely ischemic limbs is reported. The procedure studied and used consists of creating an arteriovenous fistula between the normal arterial trunk proximal to the occlusion and the deep venous trunk of the diseased limb, constricting the venous trunk proximal to the anastomosis to one third of its lumen diameter, ligating the communicating and small tributary veins distal to the constriction in the operative field. The results of the experimental and clinical studies have shown that the treated ischemic limb was quickly revascularized without undesirable influence on cardiac function. This new approach has been used in the treatment of severe ischemia involving total 212 limbs in 156 patients, and the results appeared more satisfactory than those treated with staged arteriovenous reversal.

Adult↗

Delivery by direct intrauterine transfer of gametes.

A nurse, 27, primary sterility for 5 years, had normal menstruation, normal size of uterus anterior. HSG: Rt. tube was not visible, Lt. tube slightly enlarged at ampulla. Ovaries were over-stimulated by clomiphene, HMG and hCG.8 ova were taken through vaginal aspiration under B-mode ultrasound scanning. Direct introduction of ova and washed sperms simultaneously into the uterus on Sept. 19, 1991 resulted in successful single pregnancy up to 36(+1) weeks. A 2 250 g normal baby boy was delivered on May 15, 1992 spontaneously. The base and prospect of this manoeuver are discussed with a reference to Craft's procedure.

Adult↗