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M Liao

Publications and source records attributed to M Liao.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Yeast one-hybrid system--one effective method studying DNA-protein interaction].

Yeast one-hybrid system based on the principle of yeast two-hybrid system, is applied for isolating novel genes encoding proteins that bind to a target, cis-acting regulatory element. The system may also be applied to map the DNA-binding domain of previously known, or newly identified DNA-binding proteins. Yeast one-hybrid system offers maximal sensitivity because detection of the DNA-protein interaction occurs while proteins are in their native configurations. In addition, the gene encoding the DNA-binding proteins of interest is immediately available after a library screening. In this mini-review, we introduce the principle, the experimental procedures, the applications, and the merits of yeast one-hybrid system.

DNA↗
PubMed1999

Redox-dependent DNA binding of the purified androgen receptor: evidence for disulfide-linked androgen receptor dimers.

Full-length histidine-tagged, dihydrotestosterone-bound human androgen receptor (AR) was purified to homogeneity by affinity and gel-filtration chromatography for antibody production and analysis of AR dimerization and DNA binding properties. A monoclonal antibody was raised that recognized human and rat AR epitope (360)ArgAspTyrTyrAsnPheProLeuAla(368) in the NH(2)-terminal domain and slowed migration of AR-DNA complexes in mobility shift assays. AR binding to androgen response element DNA had a K(d) of 2.0 nM and a Hill coefficient of 2.1, indicating high-affinity, cooperative binding. AR solution dimerization was detected only at >/=0.2 microM AR, and DNA binding increased dimerization up to 30-fold. Slow- and fast-migrating AR-DNA complexes were detected under different reducing conditions that differed 5-fold in their dissociation rates from DNA. Treatment with the sulfhydryl oxidizing reagent diamide formed the faster migrating, slower dissociating complex, indicating it represents disulfide-linked AR dimers bound to DNA. The results indicate that high concentrations of purified AR are required for solution dimerization and that cooperative DNA binding stabilizes two dimer forms that differ in redox state.

Animals↗
PubMed1999

Fine-resolution mapping by haplotype evaluation: the examples of PFIC1 and BRIC.

Loci for two inherited liver diseases, benign recurrent intrahepatic cholestasis (BRIC) and progressive familial intrahepatic cholestasis type 1 (PFIC1), have previously been mapped to 18q21 by a search for shared haplotypes in patients in two isolated populations. This paper describes the use of further haplotype evaluation with a larger sample of patients for both disorders, drawn from several different populations. Our assessment places both loci in the same interval of less than 1 cM and has led to the discovery of the PFIC1/BRIC gene, FIC1; this discovery permits retrospective examination of the general utility of haplotype evaluation and highlights possible caveats regarding this method of genetic mapping.

Cholestasis, Intrahepatic↗
PubMed1999

[A comparative study between clinical response and pathologic changes to preoperative chemotherapy in non-small cell lung cancer].

OBJECTIVE: To study the clinical response to preoperative chemotherapy in relation to pathologic changes in non-small cell lung cancer (NSCLC). METHODS: Forty-six stage I-IIIa NSCLC patients were given 1-2 courses of preoperative chemotherapy with mitomycin C (MMC) 6 mg.M-2 on day 1, vindesine (VDS) 2.5-3 mg.M-2 on day 1, day 8 and/or day 15, and cisplatin (DDP) 90 mg.M-2 on day 1 (MVP regimen). 'The treatment was recycled every 28 days. Clinical response was assessed according to WHO criteria. Pathologic changes of the resected tumor were categorized to 3 grades. Grade I: No tumor under gross and microscopic observation. Grade II: Grossly no tumor present but residual tumor cells under microscopic observation. Grade III: Tumor reduced in size with clear margins; marked tumor cells degeneration and necrosis accompanied with fibrosis. Grade IV: Active proliferation of tumor cells with invasion. Grade I-II was considered to be chemotherapeutically effective. RESULTS: (1) The clinical response rate was higher in patients who had received 2 courses than those received 1 course of treatment. More patients treated with 2 courses had their pathologic changes in Grade I-II than those treated with 1 course of chemotherapy but the response rate was not fully consistent with pathologic grading. (2) Pathologic grading significantly correlated with the extent of tumor involvement but not with the lymph node status. (3) Efficacy of chemotherapy should be evaluated jointly by the clinical response and grading of pathologic changes. (4) Chemotherapy with MVP regimen did not elicit severe toxic side effect. Nor did it lead to operative morbidity, operative mortality and a delay in postoperative recovery. CONCLUSION: Preoperative chemotherapy with MVP regimen is effective in the treatment of NSCLC in stage I-IIIa.

Adult↗
PubMed1999

[Studies on flavonoids from Aquilegia oxysepala Trautv. et Mey].

OBJECTIVE: To study the chemical constituents in Aquilegia oxysepala. METHOD: Various chromatographic techniques were used to separate and purify the constituents. The structures were determined by spectral analysis and chemical evidence. RESULT: Five flavonoids were isolated from the plant and identified as genkwanin, apigenin, luteonlin, swertisin and tilianin. CONCLUSION: All these compounds were isolated from the plant for the first time.

Apigenin↗
PubMed1999

[Studies on chemical constituents of Thalictrum atriplex Finet et Gagnep].

OBJECTIVE: To study the chemical constituents in the aerial part of Thalictrum atriplex. METHOD: Chromatography and spectral analysis were used to isolate and elucidate the constituents. RESULT: Six compounds were isolated from the aerial part of Thalictrum atriplex, and elucidated as protocatechuic acid, caffeic acid, p-coumaric acid, kaempferol, beta-sitosterol and N-methylcorydaldine. CONCLUSION: They are all isolated from the plant for the first time.

Caffeic Acids↗
PubMed1999

[Assay of sensitivity of Plasmodium falciparum to chloroquine, amodiaquine, piperaquine, mefloquine and quinine in Yunnan province].

AIM: To determine the sensitivity of P. falciparum to chloroquine, amodiaquine, piperaquine, mefloquine and quinine in Yunnan Province of China in 1992-1995. METHODS: Rieckmann's in vitro microtechnigue was used. The sensitivity of P. falciparum was tested to the above-mentioned antimalarials. RESULTS: The resistance rates of isolates of P. falciparum from the south, southeast and the west part of Yunnan to chloroquine and amodiaquine were 96.7% (29/30), 78.9% (30/38), 95.7% (22/23) and 100% (30/30), 85.3% (29/34), 8/9, respectively, with their corresponding ID50 of 125 nmol/L, 136 nmol/L and 176 nmol/L, and 52 nmol/L, 64 nmol/L and 72 nmol/L, respectively. All the isolates were sensitive to quinine and their ID50 were 480 nmol/L, 352 nmol/L, 608 nmol/L, respectively. The resistance rates of P. falciparum from the south part and southeast part of Yunnan to piperaquine were 96.4% (27/29), 72.9 (27/37), respectively, their ID50 were 320 nmol/L and 228 nmol/L; all the cases were sensitive to mefloqine, their ID50 were 68 nmol/L and 88 nmol/L. CONCLUSION: P. falciparum generally produces resistance to chloroquine, amodiaquine and piperaquine in Yunnan Province; the degree of resistance to chloroquine of P. falciparum from the west part of Yunnan were higher than the P. falciparum from the southeast part of Yunnan; all the isolates were sensitive to mefloquine and quinine in this region.

Amodiaquine↗
PubMed1998

The RET/PTC3 oncogene: metastatic solid-type papillary carcinomas in murine thyroids.

Our research goal is to better understand the mechanisms controlling the initiation and progression of thyroid diseases. One such disease, papillary thyroid carcinoma (PTC), is the leading endocrine malignancy in the United States. Recently, a family of related fusion proteins, RET/PTC1-5, has been implicated in the early stages of PTC. Although all five members of this family have the c-RET proto-oncogene kinase domain in their COOH terminus, little is known about how these genes alter follicular cell biology. Consequently, to answer questions related to the mechanism of the RET/PTC fusion protein action, we have devised a molecular genetic strategy to study PTC using a mouse model of thyroid disease. A new member of this fusion oncogene family, RET/PTC3, which has been implicated in more cases of solid tumor carcinoma (79%) than PTC1 or PTC2 and predominates (80%) in radiation-induced thyroid cancer of children, was investigated in our study. We have generated transgenic mice expressing human RET/PTC3 exclusively in the thyroid. These mice develop thyroid hyperplasia, solid tumor variants of papillary carcinoma and metastatic cancer. This new transgenic line will be useful in deciphering the molecular and biological mechanisms that cause PTC and histological variations in humans.

Animals↗
PubMed1998

A gene encoding a P-type ATPase mutated in two forms of hereditary cholestasis.

Cholestasis, or impaired bile flow, is an important but poorly understood manifestation of liver disease. Two clinically distinct forms of inherited cholestasis, benign recurrent intrahepatic cholestasis (BRIC) and progressive familial intrahepatic cholestasis type 1 (PFIC1), were previously mapped to 18q21. Haplotype analysis narrowed the candidate region for both diseases to the same interval of less than 1 cM, in which we identified a gene mutated in BRIC and PFIC1 patients. This gene (called FIC1) is the first identified human member of a recently described subfamily of P-type ATPases; ATP-dependent aminophospholipid transport is the previously described function of members of this subfamily. FIC1 is expressed in several epithelial tissues and, surprisingly, more strongly in small intestine than in liver. Its protein product is likely to play an essential role in enterohepatic circulation of bile acids; further characterization of FIC1 will facilitate understanding of normal bile formation and cholestasis.

Adenosine Triphosphatases↗
PubMed1998

Non-surgical therapy for patients with advanced non-small cell lung cancer.

Advanced non-small cell lung cancer (NSCLC) denotes those of TNM stage III and IV. NSCLC has its specific characteristics in respect of oncological behaviour, molecular biology, sensitivity to chemotherapy (CT) and radiotherapy (RT), and requires different therapeutic strategies in comparison with small cell lung cancer. The therapies include: (1) surgery in combination with new effective drugs is resulted in improved RR from 15% a decade ago to 40-60% today. Cisplatin (C-DDP) is the most attractive drug in the treatment of NSCLC, in lengthening the life-span of Stage IV NSCLC patients and as an indispensable sensitizer in RT. Taxinol, Gemcitabine (GEM), Navelbine (NVB), Edatrexate (ETX), CPT-11 and high dose Epirubicin (EPI HD) are recommended as new effective drugs. Response rates recently reported for the combination CT with the drugs mentioned above for NSCLC are from 30-65%, and with 8-42 weeks of MST. Induction or neoadjuvant therapies for advanced NSCLC, with 40-69% of RR, 25-29% of complete resection rate, 8-34% of CR and 17-45% of one year SR are reviewed. Eight random studies comparing MST between CT with C-DDP and best supportive care for NSCLC are statistically significant. (2) RT for Stage III NSCLC with 2 year and 5 year survivals of 20 and 5% respectively. Although such outcome is hardly acceptable, RT sensitizer, modified RT techniques and chemoradiotherapy (CRT) are imperative to improve the effect of RT in advanced NSCLC. Clinical literature suggest that CRT is better than RT, though without marked difference. Further studies and sufficient follow-up are necessary to judge the efficacy in terms of long-term survival and toxic reaction. (3) Biological therapy: gene therapy of NSCLC is still in the experimental and developmental stage. Of biological response modifier (BRM), alpha IFN in 11 cases of NSCLC with RR of 9% and MST of 14 months, IL-2 and LAK cell treatment in 11 cases with RR of 9% and MST of 18 months are reported. Instillation of BRM such as IL-2 or alpha-IFN into the pleura after drainage of cancerous effusion has been reported as the most effective for those whose RR is of 80-90% and the clinical response time is fairly long. Hematological cytokine as a protective adjuvant therapy against CT/RT toxicity makes high dose of CT possible and raises the response and patient tolerance. In multimodality therapy, it plays an important role to reduce post CT infection and septicemia.

Antineoplastic Agents↗
PubMed1998

[The clinical significance of biological characters on non-small cell lung cancer].

OBJECTIVE: To study the biological characters of 137 cases of surgically treated NSCLC and their correlation with stages, types and survival rates. METHOD: Electronmicroscopy, immunohistochemistry and FCM were employed in this prospective, randomized study. K-P curve, COX univariance and multivariance were used for statistic analysis. RESULTS: (1) Electronmicroscopy showed that 40% of squamous cancer and 40% of adenocarcinoma diagnosed microscopically were mixed type. (2) The positive rate of p53 expression increased in advanced stage of NSCLC, and the survival rate was lower in cases with positive p53 expression. (3) A higher survival rate was seen in cases with positive Hras expression. (4) Lower survival rates were seen in cases with abnormal DI and PI. (5) Miscellaneous: expression rates of c-erbB2 and PCNA were related to adenocarcinoma and mixed type electronmicroscopically confirmed respectively. CONCLUSION: From this study p53, Hras, DI, PI, c-erbB2 and PCNA were found related to stages, types and survival rates, respectively.

Adenocarcinoma↗
PubMed1998

[Determination of flavonoids and quality evaluation of Chinese traditional drug "puhuang"].

This paper deals with the determination of flavonoids and quality evaluation of Chinese Typha. Four species, viz. Typha angustata, T. angustifolia, T. davidiana and T. latifolia and eight commercial samples of Chinese traditional drug "Puhuang" were collected. Five flavonoids in pollen, filaments, female flowers and leaves were determined by HPLC using mu-Bondapak C18 column, water--isopropanol--tetrahydrofuran = 83.5:14:2.5, as mokile phase and detected at 287 nm). The qualities of different Typha species and commercial "Puhuang" samples have been compared, and the criteria for their quality control were also discussed.

Chromatography, High Pressure Liquid↗
PubMed1997

The developmental and circadian variation of melatonin receptors in the chicken spinal cord.

The developmental variation of 2-[125I]iodomelatonin binding sites in membrane preparations of the chicken spinal cords was investigated. In 19-day-old embryos, the maximum number of binding sites (Bmax) was the highest during the development. With the increase in age posthatch, the Bmax decreased gradually and significantly from 1-day-old to 4-month-old chickens. However, there were no significant changes in equilibrium dissociation constant (Kd) among all age-groups studied. To study the circadian variation, the 2-[125I]iodomelatonin binding sites in the spinal cords of 3-week-old chickens were determined at 4-hour intervals throughout a 24-hour period under a 12-hour light/12-hour dark cycle. There was a diurnal rhythm in both Bmax and Kd of [125I]iodomelatonin binding sites in which Bmax decreased and Kd increased in the dark period. The characteristics of developmental and circadian variation of melatonin receptors in the chicken spinal cord suggest that melatonin may exert a direct action on spinal cord functions and that it plays a more important role in the young animal.

Animals↗
PubMed1996

Localization and characterization of melatonin receptors in the rabbit spinal cord.

Melatonin receptors in the rabbit spinal cord were studied. Using in vitro quantitative autoradiography we have localized and characterized 2-[125I]iodomelatonin ([125I]MEL) binding sites in the central gray substance (lamina X) of the rabbit spinal cord. Saturation study revealed a single class of high affinity binding sites in the central gray substance with an equilibrium dissociation constant (Kd) of 38.8 +/- 5.25 pM and a maximum number of binding sites of 5.69 +/- 0.84 fmol/mg protein in the mid-light period. These [125I]MEL binding sites were highly specific for melatonin. Coincubation with 10 microM or 50 microM guanosine 5'-O-(3-thiotriphosphate) produced a significant change in Kd. These results suggest that melatonin receptors in the rabbit spinal cord are coupled to a guanine-nucleotide-binding protein (G-protein). Our studies suggest that melatonin exerts a direct action on the rabbit spinal cord.

Animals↗
PubMed1995

[Multimodality therapy of late stage lung cancer].

A prospective randomized study of 80 cases of stage III lung cancer treated with different multimodality therapy was carried out. Life table and Kaplan-Meir curve were employed to calculate survival rate. Log rank-multivariate analysis and time t test were used to evaluate statistical values of the 80 cases, 40 SCLC were randomly treated with either chemotherapy (CT)-surgery-CT or CT-radiotherapy (RT)-CT. The year survival rates were better in the group treated with CT-surgery-CT, a statistical difference was observed in 2yr survival rate (P < 0.05). Thus, surgical resection for SCLC was better than RT after CT. The remaining 40 cases of NSCLC were randomly treated with either CT-RT-CT or RT-CT. Multivariate analysis showed a better statistical meaning in the 20 cases treated with CT-RT-CT than the other group, their 1, 2 year survival rates were 27%, 40% and 22%, 15%, respectively. Thus preradiative CT was beneficial for survival.

Adult↗
PubMed1993

Substitution of Glu841 by lysine in the carbamate domain of carbamyl phosphate synthetase alters the catalytic properties of the glutaminase subunit.

In previous studies a Glu841-->Lys replacement in the carbamate phosphorylating domain located in the COOH half of the synthetase subunit of Escherichia coli carbamyl phosphate synthetase was shown to reduce overall synthesis of carbamyl phosphate by 4 orders of magnitude with either glutamine or NH3 as nitrogen donor (Guillou et al., 1992). In the present study, the mutant enzyme has been further analyzed for its glutamine hydrolytic activity. The glutaminase activity of the mutant enzyme has the following properties. (1) In the absence of other substrates the turnover number is only marginally different from that of the wild-type complex. (2) The Km for glutamine is 60 times higher than in wild-type complex and three times higher than in the separated glutaminase subunit. (3) In the present study wild-type carbamyl phosphate synthetase has been shown to catalyze glutamine hydrolysis by a mechanism involving an enzyme-bound acyl ester intermediate (gamma-glutamyl thioester). This intermediate is formed and is hydrolyzed with rates consistent with overall glutamine hydrolysis. At physiological concentrations of glutamine (1.2 mM), the steady-state concentration of gamma-glutamyl thioester is 0.3 mol/mol of wild-type enzyme. Under the same conditions, only 0.02 mol of thioester is measured in the mutant enzyme. Maximal accumulation of this covalent intermediate by the mutant enzyme required 10 times higher concentrations of free glutamine. (4) The rate of reaction with 2-amino-4-oxo-5-chloropentanoate, a glutamine analog known to specifically alkylate an active site cysteine residue, is 2 orders of magnitude slower in the mutant.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Effect of antihypertensive therapy on the kidney in patients with diabetes: a meta-regression analysis.

OBJECTIVE: To assess the relative effect of different antihypertensive agents on proteinuria and renal function in patients with diabetes. DATA SOURCES: We used MEDLINE and bibliographies in recent articles to identify studies of the effects of antihypertensive agents on renal function in patients with diabetes. STUDY SELECTION: We selected 100 controlled and uncontrolled studies that provided data on renal function, proteinuria, or both, before and after treatment with an antihypertensive agent. DATA EXTRACTION: Data on blood pressure, renal function, proteinuria, patient characteristics (for example, age, sex, and type of diabetes), and study design (for example, random allocation and the use of a placebo) were extracted from selected studies. DATA SYNTHESIS: Multiple linear regression analysis indicated that angiotensin-converting enzyme (ACE) inhibitors decreased proteinuria independent of changes in blood pressure, treatment duration, and the type of diabetes or stage of nephropathy, as well as study design (P < 0.0001). Reductions in proteinuria from other antihypertensive agents could be entirely explained by changes in blood pressure. Blood pressure reduction in itself was associated with a relative increase in glomerular filtration rate (regression coefficient [+/- SE], 3.70 +/- .92 mL/min for each reduction of 10 mm Hg in mean arterial pressure; P = 0.0002); however, compared with other agents, ACE inhibitors had an additional favorable effect on glomerular filtration rate that was independent of blood pressure changes (3.41 +/- 1.71 mL/min; P = 0.05). CONCLUSION: Angiotensin-converting enzyme inhibitors can decrease proteinuria and preserve glomerular filtration rate in patients with diabetes. These effects occur independent of changes in systemic blood pressure.

Adolescent↗