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Biomedical subjects

W Li

Publications and source records attributed to W Li.

At least 271 records · Page 15Linked to original sources
PubMed2001

A validated method for quantitative determination of saponins in notoginseng (Panax notoginseng) using high-performance liquid chromatography with evaporative light-scattering detection.

A gradient high-performance liquid chromatographic (HPLC) method with evaporative light-scattering detection (ELSD) for the determination of major saponins in a Chinese traditional herbal medicine, Panax notoginseng, is described. Samples were analysed by means of a reverse-phase column (Waters Spherisorb ODS-2, C-18) using acetonitrile and water under gradient conditions as the mobile phase over 60 min. The ELSD used was set at an evaporating temperature of 35 degrees C and pressurized air pressure of 3.4 bars. The detection limit (signal/noise > 3) of the saponins was 50 ng. The method was validated by inter- and intra-day assays and recovery tests.

Chromatography, High Pressure Liquid↗
PubMed2001

Characterization of a Ca2+-dependent protein kinase from rice root: differential response to cold and regulation by abscisic acid.

The Ca2+-dependent protein kinases (CDPKs) and abscisic acid (ABA) are known to be involved in low-temperature stress response. The focus of this study was to characterize the 45 kDa protein kinase identified in the crude extract of rice (Oryza sativa L.) seedling roots in response to cold (5 degrees C) stress. The activity of the 45 kDa protein kinase decreased at low temperature as evident by an in-gel kinase assay using histone III-S as a substrate. Also, the Ca2+-dependent activity of this protein kinase was suppressed by cold in the membrane fractions of the root. A general protein kinase inhibitor and Ca2+ chelator inhibited the activity of the 45 kDa protein kinase, suggesting that it was a plant CDPK. The 45 kDa CDPK identified was found to be independent of photosynthetic tissues such as the leaf and leaf sheath of rice seedlings, supporting a direct sensing mechanism in the roots of rice seedlings to cold stress. The suppressed activity of the 45 kDa CDPK was reverted by supplementing with 5 microM ABA under cold stress. The 45 kDa CDPK activity was stronger in the cold-tolerant variety of the 4 types tested than it was in the cold-sensitive one. These results suggest the involvement of endogenous ABA in regulating the activity of the 45 kDa CDPK in response to cold stress.

Abscisic Acid↗
PubMed2001

Digoxin-like and digitoxin-like immunoreactive substances in elderly people. Impact on therapeutic drug monitoring of digoxin and digitoxin concentrations.

We compared digoxin-like (DLIS) and digitoxin-like (DTLIS) immunoreactive substance concentrations for 30 people older than 65 years with those for 25 people younger than 50. None received digoxin or had liver disease, uremia, or volume expansion. We found no DTLIS in any specimen, and only 1 specimen from an elderly person demonstrated a low DLIS concentration. In addition, for 22 non-volume expanded patients (8 younger than 50 years and 14 older than 65) receiving digoxin, the fluorescence polarization (FPIA) and the microparticle enzyme (MEIA) immunoassays revealed comparable serum digoxin concentrations, indicating an insufficient DLIS concentration to interfere with digoxin immunoassay results. Therefore, elderly people who are not volume expanded do not have elevated DLIS or DTLIS concentrations. Furthermore, for patients with liver disease or uremia (18 older than 65 years and 20 younger than 50), the DLIS and DTLIS concentrations were elevated. Finally, for 5 patients with liver disease who received digoxin, serum digoxin concentrations were lower by MEIA and higher by FPIA, indicating the patients had elevated DLIS levels that interfered with the assays. Elevated DLIS and DTLIS concentrations are associated with volume expansion and not age.

Aged↗
PubMed2001

Identification of the calcium-sensing receptor in the developing tooth organ.

Calcium (Ca2+) is a critical component of tooth enamel, dentin, and the surrounding extracellular matrix. Ca2+ also may regulate tooth formation, although the mechanisms for such action are poorly understood. The Ca2+-sensing receptor (CaR) that is expressed in the parathyroid gland, kidney, bone, and cartilage has provided a mechanism by which extracellular Ca2+ can regulate cell function. Because these tissues play an important role in maintaining mineral homeostasis and because Ca2+ is hypothesized to play a crucial role in tooth formation, we determined whether the CaR was present in teeth. In this study, using immunohistochemistry, CaR protein was detected in developing porcine molars localized in the predentin (pD), early secretory-stage ameloblasts, maturation-stage smooth-ended ameloblasts (SA), and certain cells in the stratum intermedium. CaR protein and messenger RNA (mRNA) were detected also in an immortalized ameloblast-like cell line (PABSo-E) using immunofluorescence, reverse-transcription polymerase chain reaction (RT-PCR), and Northern analysis. Based on the observation that the CaR is expressed in cultured ameloblasts, we determined whether increments in medium Ca2+ concentration could activate the intracellular Ca2+ signal transduction pathway. In PABSo-E cells, increasing extracellular Ca2+ in the medium from 0 (baseline) to 2.5mM or 5.0 mM resulted in an increase in intracellular Ca2+ above baseline to 534 +/- 69 nM and 838 +/- 86 nM, respectively. Taken together, these results suggest that the CaR is expressed in developing teeth and may provide a mechanism by which these cells can respond to alterations in extracellular Ca2+ to regulate cell function and, ultimately, tooth formation.

Ameloblasts↗
PubMed2001

CT features of pulmonary alveolar proteinosis.

OBJECTIVE: This investigation describes the CT features of pulmonary alveolar proteinosis in a large group of patients. MATERIALS AND METHODS: A retrospective review of 139 chest CT scans (79 thick-section scans and 60 thin-section scans) from 27 patients with pathologically proven pulmonary alveolar proteinosis was performed. Two independent observers assessed the intraslice patterns and zonal distribution of disease on three CT images of each lung. The observers also graded the percentage of ground-glass opacities, air-space opacities, fibrosis, interlobular opacities, intralobular opacities, and emphysema in each slice. CT scans obtained before and after lavage related to 12 whole-lung lavage treatments on nine patients were evaluated. RESULTS: The dominant intraslice pattern was geographic, but a diffuse pattern was sometimes seen. The most common zonal pattern was uniform; a lower zone predominance was next most frequent. Ground-glass, air-space, and fibrotic opacities had a generally homogeneous craniocaudal distribution, but there was a trend toward more interlobular opacities at the lung bases (p < 0.002). Ground-glass opacities were seen on at least one scan in 100% of the patients. Interlobular opacities (85%), air-space opacities (78%), substantial fibrosis (7%), and intralobular opacities (7%) occurred less frequently. Compared with thick-section images, thin-section images showed more interlobular opacities, but no difference in ground-glass, air-space, or fibrotic disease. The proportion of lung affected by ground-glass and interlobular opacities decreased significantly (p < 0.05) after lavage. CONCLUSION: Pulmonary alveolar proteinosis does not present only with alveolar disease. The CT appearance typically combines different types of opacities with a geographic pattern and a uniform zonal distribution with variation over time.

Adult↗
PubMed2001

Using CT and cholangiography to diagnose biliary tract carcinoma complicating primary sclerosing cholangitis.

OBJECTIVE: The objective of our study was to determine the value of CT and cholangiography for diagnosing biliary tract carcinoma complicating primary sclerosing cholangitis. MATERIALS AND METHODS: One hundred thirteen abdominal CT examinations and cholangiograms in 45 patients with primary sclerosing cholangitis, including 18 patients with established biliary tract carcinoma, were analyzed for tumor. Four radiologists who were unaware of the presence or absence of carcinoma rated each study as to the probability of malignancy. Receiver operating characteristic curve analysis was used to assess the diagnostic performance of CT and cholangiography, the value of imaging signs, and the degree of inter-observer variation in interpretation. Sensitivity and specificity values were calculated. RESULTS: CT outperformed cholangiography in the detection of carcinoma. The average area under the receiver operating characteristic curve was 0.82 for CT and 0.57 for cholangiography (p = 0.003). Sensitivity and specificity for detecting carcinoma using CT were good, with average values of 82% and 80%, respectively. Average sensitivity and specificity for cholangiography were 54% and 53%, respectively. The most reliable sign of tumor on CT was a discrete mass. Progressive biliary dilatation on sequential studies was the most useful sign on cholangiography. Interobserver agreement assessed using the Cronbach alpha was fair for cholangiography and good for CT. CONCLUSION: CT provides good sensitivity and specificity and significantly outperforms cholangiography in detecting biliary tract carcinoma complicating primary sclerosing cholangitis. Despite limitations, CT and cholangiography provide useful information not otherwise available in the treatment of patients with primary sclerosing cholangitis.

Adult↗
PubMed2001

Inhibition by ginseng of colon carcinogenesis in rats.

The inhibitory effects of ginseng on the development of 1,2-dimethylhydrazine (DMH)-induced aberrant crypt foci (ACF) in the colon were investigated in rats. Male, 6-week-old rats were injected with DMH once a week for 4 weeks. Rats in Groups 1 and 2 were fed diets containing red and white ginseng, respectively, at a dose of 1% for 5 weeks, starting one week before the first treatment of DMH. Animals in Groups 3 and 4 received red or white ginseng for 8 weeks starting after DMH treatment. Group 5 served as a carcinogen control group. Numbers of ACF with at least four crypts were significantly reduced in the colon of Group 2 treated with red ginseng combined with DMH. Moreover, rats were injected with DMH 4 times at one-week intervals. They were also fed diets containing 1% red or white ginseng or the control diet throughout 30 days of the experiment. Treatment with red ginseng resulted in a significant decrease of 5- bromo-2'-deoxyuridine labeling indices in colonic crypts comprising ACF. These findings suggest that dietary administration of red ginseng in combination with DMH suppresses colon carcinogenesis in rats, and the inhibition may be associated, in part, with inhibition of cell proliferation, acting on ACF in the colonic mucosa.

1,2-Dimethylhydrazine↗
PubMed2001

Absorption and tissue distribution of zeaxanthin and lutein in rhesus monkeys after taking Fructus lycii (Gou Qi Zi) extract.

PURPOSE: To study serum and tissue levels of zeaxanthin and lutein after feeding rhesus monkeys an extract of Fructus lycii (gou qi zi). METHODS: A carotenoid-containing fraction (P1) from an extract of F. lycii (equivalent to 2.2 mg zeaxanthin) was fed to three rhesus monkeys for 6 weeks as a daily dietary supplement through a nasogastric tube. Three other monkeys were fed with the vehicle (olive oil) similarly for 4 weeks as a control. Another three animals were fed with normal diet only. All animals were killed 4 hours after the last dose. Samples of serum, liver, spleen, brain, and retina were analyzed for zeaxanthin and lutein by high-pressure liquid chromatography. RESULTS: The basal levels of zeaxanthin and lutein in the monkey sera were 3.0 +/- 1.6 ng/ml (range, 2.3-4.8) and 31.5 +/- 12.2 ng/ml (range, 22.3-42.5), respectively. Serum levels of zeaxanthin and lutein in the P1-fed group were significantly higher than those of vehicle control (P<0.05). Besides the retina, the liver had the highest zeaxanthin and lutein levels, whereas the levels in the brain were undetectable. P1 supplement appeared to elevate zeaxanthin levels in liver and spleen. The level of lutein was higher than that of zeaxanthin in the maculae of rhesus monkeys. However, there were no detectable carotenoids in the peripheral and the equatorial regions of the monkey retina. P1 treatment elevated zeaxanthin density but not lutein in the macula. CONCLUSIONS: Serum levels and macular density of zeaxanthin was raised by feeding a carotenoid-containing fraction of F. lycii. Therefore, F. lycii is a good dietary source of zeaxanthin supplement.

Animals↗
PubMed2001

Mesenchymal-epithelial interactions in bladder smooth muscle development: effects of the local tissue environment.

PURPOSE: We have previously shown that mesenchymal-epithelial interactions are necessary for the development of bladder smooth muscle. Specifically without fetal or adult urothelium embryonic rat bladder mesenchyma does not differentiate into smooth muscle. The mechanism responsible for this interaction is not known, although it is postulated that diffusable growth factors have a role. Our hypothesis is that diffusable factors within adult rat bladders influence smooth muscle differentiation. MATERIALS AND METHODS: Chimeric bladders were created by surgically implanting 14-day embryonic rat bladder mesenchyma before smooth muscle differentiation into the detrusor space of adult syngeneic hosts to test whether the host urothelium would induce smooth muscle differentiation without being in direct contact with fetal bladder mesenchymal tissue. Sub-detrusor pockets were created between the serosa and smooth muscle layer, between the smooth muscle layer and lamina propria, and between the lamina propria and urothelium in direct contact with urothelium. Controls consisted of intact 14-day embryonic rat bladders with the urothelium not removed, and 14-day embryonic bladder mesenchyma recombined with urothelium (direct contact) placed within the sub-detrusor space of the bladder and under the renal capsule. RESULTS: Immunohistochemical staining with antibodies directed against smooth muscle alpha-actin and urothelium (cytokeratin 7) revealed smooth muscle differentiation in intact embryonic bladders and bladder mesenchyma plus urothelium recombinants in contrast to bladder mesenchyma alone, which had no alpha-actin staining (morphometric smooth muscle analysis p = 0). There was no alpha-actin staining in chimeric bladders even when bladder mesenchymal grafts were placed directly in contact with host urothelium. In addition, bladder mesenchyma plus urothelial recombinants within the host bladder had less alpha-actin staining than their counterparts placed under the renal capsule (p = 0.001). CONCLUSIONS: A diffusable factor most likely exists within adult rat bladders that inhibits smooth muscle differentiation.

Animals↗
PubMed2001

[Identification of traditional Chinese medicine Baizhi with near-infrared spectrum].

In this paper, 8 kinds of traditional Chinese medicines Baizhi were identified by near-infrared spectrum, coping with pattern recognition. The results showed that near-infrared spectrum method in identifying traditional Chinese medicines Baizhi was not only simple, rapid, but also using few examples, noninvasion. This method provided referential information for identifying these traditional Chinese medicines.

Angelica↗
PubMed2001

Effect of progesterone on the contractile response of isolated pulmonary artery in rabbits.

The purpose of this study was to assess the direct effect of progesterone on rabbit pulmonary arteries and to examine the mechanism of its action. Rings of pulmonary artery from male rabbits were suspended in organ baths containing Krebs solution, and isometric tension was measured. The response to progesterone was investigated in arterial rings contracted with noradrenaline (NA), KCl, and CaCl2. The effects of endothelium, nitric oxide (NO), prostaglandins, cyclic GMP (cGMP), and the adrenergic beta-receptor on progesterone-induced relaxation were also assessed. Progesterone inhibited the vasocontractivity to NA, KCl, and CaCl2, and relaxed rabbit pulmonary artery. The relaxing response of progesterone in pulmonary artery was significantly reduced by removal of endothelium, inhibitors of nitric oxide synthase and guanylate cyclase, but not by prostaglandin synthase inhibitor and blockage of the adrenergic beta-receptor. In Ca2+-free (0.1 mM EGTA) Krebs solution, progesterone inhibited NA-induced contraction that was intracellular Ca2+-dependent, but didn't affect the contraction of extracellular Ca2+-dependent component. Our results suggest that progesterone induces relaxation of isolated rabbit pulmonary arteries partially via NO and cGMP. Progesterone may also inhibit Ca2+ influx through potential-dependent calcium channels (PDCs) and Ca2+ release from intracellular stores.

Animals↗
PubMed2001

[Experimental and mechanism analyses on HCl emission control during PVC combustion in fixed beds].

Incineration of chloridated plastic (PVC) in solid wastes contributes much to HCl pollutant in air environment. The characteristics of HCl emissions and reduction during PVC combustion were conducted in a nearly isothermal, externally heated, horizontal quartz-tube reactor. With increasing temperature from 700 to 900 degrees C, the conversion of HCl increased leniently from 82.5% to 88.3%. High excess air factor enhanced a small amount of HCl existing in form of Cl2. The calcium-based sorbents including CaCO3, Ca(OH)2, Ca(CH3COO)2 exhibited high HCl capture efficiencies from 68% to 79%, while magnesium-based sorbent less than that of 3%. Influences of operational variables, i.e., size of sorbent, Ca/Cl molar ratio and combustion fume compositions, on the HCl reduction were discussed. From a point of view of equilibrium constant of dechloridization reaction the experimental results were explained in detail.

Hot Temperature↗
PubMed2001

[Nucleotide sequence analysis of the hepatitis B virus X-precore region in chronic hepatitis B].

In chronic hepatitis B virus (HBV) infection, hepatitis B e antigen (HBeAg) is seroconverted from positive to negative. HBeAg is associated with active replication of the HBV and a high disease activity. To elucidate the relation between HBV X-precore region mutation and HBeAg status, HBV replication and liver function were surveyed in chronic hepatitis B patients. HBV DNA was isolated from fifteen serum samples of seven patients with chronic hepatitis B, and the X-precore region was amplified by PCR and sequenced. Each sequence was compared with the consensus sequence of each patient. The most frequently observed mutations were A to T at nt. 1762 and G to A at nt. 1764 in the core promoter region and G to A at nt. 1896 in the precore region. These mutations were more commonly found in HBeAg-negative serum samples than in HBeAg-positive (p < 0.001, respectively). Of 7 serum samples with the wild type or wild/mutant mixed type in the precore region, 6 were HBeAg-positive and had a high HBV DNA polymerase (DNA-p) activity and serum alanine aminotransferase (ALT) elevation. On the other hand, 6 serum samples with the mutant type only were HBeAg-negative and had a low DNA-p activity and normal ALT level. Interestingly, 2 serum samples with the mutant type only had a high DNA-p activity and serum ALT elevation, despite being HBeAg-negative. Core promoter region mutation was not associated with HBV markers or serum ALT level. In conclusion, mutation at nt. 1896 in the precore region causes seroconversion from HBeAg-positive to -negative and is accompanied by reductions of viral replication and hepatitis activity.

Adult↗
PubMed2001

[Mutations of mitochondrial 12S rRNA gene in type 2 diabetes].

OBJECTIVE: To investigate mutations at points 1310, 1438 and 1442 of mitochondrial 12S rRNA gene in Chinese type 2 diabetes and screen for new mutations associated with type 2 diabetes in this area. METHODS: The mitochondrial DNAs (mtDNAs) of 86 patients with type 2 diabetes and those of 70 normal controls were analyzed using PCR-SSCP and PCR product direct sequencing technique. RESULTS: One patient was found with the mitochondrial DNA G --> A mutation at point 1438, and one with the G two head right arrow A mutation at point 1442, whereas none of the normal controls was found to have mutation at these two points. No C --> T mutation at nucleotide pair 1310 of the mitochondrial 12S rRNA gene was identified. CONCLUSION: The G --> A mutation at points 1438 and 1442 is likely to be associated with the development of type 2 diabetes; the occurrence of the C -->T mutation at point 1310 is probably rare in the blood cells, and the development of type 2 diabetes may be related to heterogeneity in mitochondrial genetic changes.

Adult↗
PubMed2001

Molecular analysis in evaluating the sentinel node in malignant melanoma.

The most powerful predictor of cancer mortality in solid tumors is the status of regional lymph nodes. If the presence or absence of regional nodal metastases will determine which patient receives formal dissection or which patient enters adjuvant therapy, then a technique is needed to accurately screen lymph node samples for occult disease. Routine histopathologic examination commonly underestimates the number of patient with metastases. The use of reverse transcription-polymerase chain reaction (RT-PCR) method increased the detection of nodal metastases exponentially. Studies have shown that RT-PCR is a sensitive, reproducible, and efficient technique with prognostic significance. If identification of micrometastases through RT-PCR can lead to improved clinical outcome, then this more accurate method of staging would become the new standard in cancer care.

Antigens, Differentiation↗
PubMed2001

[Trends in the pharmaceutical research of ribonucleases and their therapeutic uses].

As one of the most popular model enzymes, the structure and evolution of ribonucleases (RNases) have been studied thoroughly. But until recently, scientists found out that RNases demonstrated a series of important biological functions, such as controlling blood vessel formation, killing tumor cells and inhibiting virus. Now immunotoxin, the antibody-toxin conjugate, becomes a research hot spot. RNases with cytotoxicity are the candidates for the toxin moiety of the immunotoxins. In this paper, the newly found cytotoxic functions of RNases are discussed in detail.

Animals↗
PubMed2001

[Comparative effects of decreasing viscosity in different preparations of Chinese angelica root and ginseng].

OBJECTIVE: To compare the effects of different preparations of Chinese angilica root and ginseng on decreasing whole blood viscosity and plasma viscosity in rats. METHOD: The hemorheological method was used in vivo or in vitro and a Decreasing Viscosity Index (DIV) was defined as a comparative scalar. RESULTS: In the effect of the groups of Chinese angilica root on decreasing viscosity, the effect of whole root group was the best and the effect of main root group was better than that of the tributary root group. Meanwhile the same effect of transplant wild ginseng group was greater than that of dried raw ginseng group. CONCLUSION: This work provided some fundamental evidences for clinical application and pharmacological data for the quality evaluation.

Angelica sinensis↗