Biomedical subjects

D Li

Publications and source records attributed to D Li.

At least 199 records · Page 11Linked to original sources

PubMed2001

Androgen responsiveness of the pituitary gonadotrope cell line LbetaT2.

Androgens have a profound effect on the hypothalamic-pituitary axis by reducing the synthesis and release of the pituitary gonadotropin LH. The effect on LH is partly a consequence of a direct, steroid-dependent action on pituitary function. Although androgen action has been well studied in vivo, in vitro cell models of androgen action on pituitary gonadotropes have been scarce. Recently, an LH-expressing cell line, LbetaT2, was generated by tumorigenesis targeted to the LH-producing cells of the mouse pituitary. The purpose of these studies was to determine the presence of androgen receptor (AR) and establish its function in this cell line. RT-PCR analysis indicated that the LbetaT2 cell line expresses AR mRNA. Transient transfection assays, using the mouse mammary tumor virus (MMTV) promoter, showed that a functional AR is also present. Testosterone (TEST), dihydrotestosterone (DHT), 7alpha-methyl-19-nortestosterone (MENT), and fluoxymesterone (FLUOXY) increased reporter gene activity in the rank order of potencies MENT>DHT> TEST>FLUOXY. Additionally, activation of MMTV promoter activity by DHT in LbetaT2 cells was diminished by the AR antagonists casodex and 2-hydroxy-flutamide, indicating that the effects of DHT are mediated through AR. In summary, these studies showed that the LbetaT2 cell line is a useful model for the evaluation and molecular characterization of androgen action in pituitary gonadotropes.

Androgen Receptor Antagonists↗

PubMed2001

Effect of dietary modification of muscle long-chain n-3 fatty acid on plasma insulin and lipid metabolites, carcass traits, and fat deposition in lambs.

In a previous study we showed that feeding fish meal significantly increased muscle long chain n-3 fatty acids (FA) and hot carcass weight. In this study we compared the effect of fish meal and fish oil on increasing muscle long-chain FA. We also investigated whether the increase in carcass weight was due to the effect of dietary enrichment of muscle long-chain n-3 FA on muscle membrane phospholipids and(or) to rumen by-pass protein provided by fish meal. Forty crossbred ([Merino x Border Leicester] x Poll Dorset) wether lambs between 26 and 33 kg BW were randomly assigned to one of five treatments: 1) basal diet of oaten:lucerne chaff (Basal); 2) Basal + fish meal (9% DM) = FM; 3) Basal + fish oil (1.5% DM) with protected sunflower meal (9% DM ) = FOSMP; 4) Basal + fish oil (1.5% DM) = FO; or 5) Basal + protected sunflower meal (10.5% DM) = SMP. Daily intake of ME (9.60 - 10.5 MJ ME/d) and CP (150 to 168 g/d) in all treatments was kept similar by varying the ratio of oaten:lucerne chaff and by feeding the animals at 90% ad libitum intake. Blood samples were collected at the start of the experiment and on the day (d 42) prior to slaughter. Lambs were then slaughtered at a commercial abattoir. At 24 h postmortem carcass traits were measured and longissimus thoracis muscle taken for analysis of FA of phospholipid and triglyceride fractions. Lambs fed FO and FOSMP showed a marked increase in muscle longchain n-3 FA (P < 0.001) and a reduction in magnitude of the rise in insulin concentration (P < 0.001) after feeding compared with lambs fed Basal and SMP diets. Lambs in FM had a moderate increase (P < 0.001) in muscle long-chain n-3 FA content. Compared with Basal diet, both plasma total cholesterol (P < 0.02) and high-density lipoprotein cholesterol (P < 0.001) levels were greater in SMP and less in FO and FOSMP treatments. The i.m. fat content was reduced (P < 0.05) in FM and FO treatments, but carcass weight was increased only with fish meal (P < 0.03). Adding SMP to FO produced muscle with an intermediate level of i.m. fat, whereas muscle long-chain n-3 FA, i.m. fat, and insulin concentration were unchanged with SMP treatment. These results indicate that an increase in carcass weight in FM may be due to the supply of ruminally undegraded protein. They also suggest that fish oil along with fish meal can increase long-chain n-3 FA content in phospholipid of muscle membrane. This may be associated with reduced i.m. fat content and altered insulin action and lipoprotein metabolism.

Adipose Tissue↗

PubMed2001

Relationship between the concentrations of plasma phospholipid stearic acid and plasma lipoprotein lipids in healthy men.

This study investigated the correlation between the plasma phospholipid (PL) saturated fatty acid (SFA) concentration (as a surrogate marker of SFA intake) and plasma lipid and lipoprotein lipid concentrations in 139 healthy Australian men aged 20-55 years old with widely varying intakes of saturated fat (vegans, n=18; ovolacto vegetarians, n=43; moderate meat eaters, n=60; high meat eaters, n=18). Both the ovolacto vegetarian and vegan groups demonstrated significant decreases in plasma total cholesterol (TC), low-density-lipoprotein cholesterol (LDL-C) and triacylglycerol concentrations compared with both the high-meat-eater and moderate-meat-eater groups. Total SFA and individual SFA [palmitic acid (16:0), stearic acid (18:0) and arachidic acid (20:0)] in the plasma PL were significantly lower in both the ovolacto vegetarian and vegan groups than in both the high- and moderate-meat-eater groups, while myristic acid (14:0) was significantly lower in the vegans than in the high-meat-eaters. Bivariate analysis of the results showed that the plasma PL stearic acid concentration was strongly positively correlated with plasma TC (P<0.0001), LDL-C (P<0.0001) and triacylglycerol (P<0.0001), with r(2) values of 0.655, 0.518 and 0.43 respectively. In multiple linear regression, after controlling for potential confounding factors (such as exercise, dietary group, age, body mass index, plasma PL myristic acid, palmitic acid and arachidic acid, and dietary total fat, saturated fat, cholesterol, carbohydrate and fibre intake), the plasma PL stearic acid concentration was still strongly positively correlated with plasma TC (P<0.0001) and LDL-C (P=0.006) concentrations. Based on the present data, it would seem appropriate for the population to reduce their dietary total SFA intake rather than to replace other SFA with stearic acid.

Adult↗

PubMed2001

Key regulatory oxysterols in liver: analysis as delta4-3-ketone derivatives by HPLC and response to physiological perturbations.

A number of oxysterols have been implicated in metabolic regulation. Key among these are (24S),25-epoxycholesterol and (24S)-hydroxycholesterol, high affinity ligands for the nuclear transcription factor liver X receptor alpha; 27-hydroxycholesterol, a bile acid synthetic intermediate; and 25-hydroxycholesterol, which has been used to study regulation of lipid metabolism by the sterol regulatory element-binding protein family of transcription factors. Investigation of the physiological importance of these compounds in vivo has been hampered by lack of analytical methods to reproducibly and accurately determine their concentrations in tissues. This article describes a method designed to determine quantitatively the amounts of these important side-chain oxysterols by derivatization to the Delta4-3-ketones followed by high performance liquid chromatography. The method was validated with known standards and then was used to determine the concentrations of these oxysterols in rodent liver under various physiological conditions. All four oxysterols were present in the picogram per milligram protein range and have distinct subcellular distributions and responses to physiological perturbations in vivo.

Animals↗

PubMed2001

[Research advances of multidimensional reconstruction of ultrasonic heart images].

The methods, present research situation, existing problems, and application foreground of multidimensional reconstruction of ultrasonic heart images are discussed in the present paper. According to the procedure of multidimensional reconstruction of ultrasonic heart images, the discussions are presented in respect to image acquisition, processing, and display. Based on the present situation and existing problems, the future development and application foreground are proposed.

Echocardiography, Three-Dimensional↗

PubMed2001

[Review of filtering algorithms for medical ultrasonic images].

Several kinds of filters for medical ultrasonic images, such as multidimensional filter, adaptive weighted filter (for example, adaptive weighted median filter), adaptive window selecting filter (for example, homogeneous region growing mean filter and adaptive speckle suppression filter) and two-step filter, are introduced. The existing problems and the progress trend are also discussed. Some application instances for medical ultrasonic images of the filters discussed and the performance of the filters presented are based on the present authors' practice.

Algorithms↗

PubMed2001

Toward an integrative understanding of social phobia.

Our objective was to examine the neurobiology of social phobia from the perspectives of basic sciences, genetics, immunology, neuroendocrinology, neurotransmission and neuroimaging and to provide an integrated understanding of social phobia in the framework of a hypothetical neural circuit. Family and twin studies provide evidence that social phobia is heritable with significant genetic influence, and molecular genetics offers possibilities in understanding the nature of the trait that is transmitted. The biologic distinctiveness of social phobia from anxiety disorders and physiological validation of differences between generalized and discrete social phobia subtypes have been implicated in genetic, naturalistic and chemical challenge studies. Evidence of specific dysfunction of dopaminergic, serotonergic, noradrenergic and GABAergic (gamma-aminobutyric acid) neurotransmitter systems has been presented in animal models, challenge studies and treatment investigations. Preliminary neuroimaging research supports previous studies suggesting striatal dopaminergic dysfunction in social phobia and suggests the importance of functional circuits. A neural circuit involving the striatum, thalamus, amygdala and cortical structures may provide a framework for integrating much of the current knowledge on the neurobiology of social phobia.

Animals↗

PubMed2001

[Atmospheric particulate mercury concentration in Changchun City and its dry deposition flux].

From July 1999 to January 2000, the particulate mercury(Hg(p)) concentration of five function sites and one contrast site were determined. In non-heating time, the particulate mercury concentration in urban atmosphere ranged from 0.022 to 0.398 ng.m-3 with an average of 0.145 ng.m-3 and the contrast site with an average of 0.084 ng.m-3. In heating time, the Hg(p) concentration in urban was in the range of 0.148-1.984 ng.m-3 with an average of 0.461 ng.m-3 and with an average of 0.211 ng.m-3 in the contrast site. The Hg(p) concentration in heating time was two times higher than that of non-heating time. Coal fire and wind-blown soil material were the two important sources of Hg(p). Wind-blown soil material contributed 7.9%-38.5% of the Hg(p) with an average of 24.1% in urban. Use theory model to estimate the dry deposition flux with the results of 43.06 micrograms.(m2.a)-1 in urban and 21.28 micrograms.(m2.a)-1 in the contrast site.

Air Pollutants↗

PubMed2001

[The absorbed rate and distribution rule of rare earth elements in wheat by 141Ce as tracer].

The study on absorption, distribution rules and transportation rates of cerium in the interface of water-wheat by 141Ce in culture solution were carried out. The results showed that the concentrations of cerium in wheat seedling were gradually increased during the experiment, and so did the same after increasing the concentration of cerium adding in the culture solution. The concentrations of cerium in roots of winter wheat were significantly high than that in tops (steam & leave). The absorption rates of cerium in wheat with different treatments of cerium were distinct. The quantitative formulas, which describe the rule of absorption rate and culture time, was given resulting from the fit of the experimental data.

Adsorption↗

PubMed2001

[Auto-detection of contour in echocardiographic images based on active contour model].

Contour detection is one of the most difficult problems in the multi-dimensional reconstruction of echocardiographic images. A method based on active contour model is presented in the present paper to solve this problem. First, according to the characteristic of the ultrasonic medical images, an adaptive weighted median filter is used to suppress speckle noise and an adaptive threshold value is selected to get binary image. Then, mathematical morphological treatment is utilized to get the initial contour. At last, active contour model is employed to revise the initial contour and get the accurate final contour. Experiments with real and interpolated ultrasonic images are presented. The results show the effectiveness of this method. This method has practical use in the multi-dimensional reconstruction of ultrasonic medical images.

Algorithms↗

PubMed2001

[Effects of phenytoin on structural aberration of human sperm chromosomes in vitro].

OBJECTIVE: To detect the mutagenic effects of phenytoin on human sperm chromosomes. METHODS: The mutagenic effects of phenytoin at 10, 20 and 40 microgram/ml were tested by an in vitro testing system of human sperm chromosomes, with leomycin A5 as a positive control and mutagen-free solution as the blank control. RESULTS: The frequencies of sperm with structural chromosomal aberrations and breakages of sperm chromosomes in the groups of 10 microgram/ml, 20 microgram/ml and 40 ug/ml of phenytoin were all higher than those in the blank control, but only in the group of 40 ug/ml, the elevated frequencies were statistically significant (P<0.005, P<0.05). CONCLUSION: Phenytoin has probably mutagenic potential effect on human sperm cells.

Adult↗

PubMed2001

[Degradation of trichloroethylene by discharge plasma process].

Two types of discharge and two kinds of discharge reactors was employed to decompose trichloroethylene (TCE) in air. The results showed that both pulsed discharge and AC discharge were efficient to the degradation of TCE. Under the pulsed discharge with peak voltage of 42 kV, gas resident time of 15 s and TCE initial concentration of 1350 mg/m3, the degradation efficiency of TCE was close to 100% in the hallow reactor and the higher voltage results in a higher degradation efficiency. For the AC discharge, the degradation efficiency of TCE reached 90% with applied voltage of 30 kV. Meanwhile, increasing the applied frequency of AC voltage can enhance the degradation of TCE. The energy consumption for TCE degradation by AC discharge was higher than that by pulsed discharge. The energy consumption for TCE degradation efficiency of 80% by pulsed and AC discharge were 4.9 W.h/m3 and 116 W.h/m3, respectively. In addition, the energy consumption in the packed reactor was higher comparing with that in the hallow one.

Trichloroethylene↗

PubMed2001

[Effect of phosphate on the exchangeable form and the bioavailability of exogenous neodymium in soil].

Effects of phosphate on the exchangeable form and the bioavailability of exogenous neodymium (Nd) in soil were studied with 147Nd isotopic tracer. Exchangeable Nd was extracted with solution (pH8.2) of NaAc. The results indicated that Nd beyond 99.5% was adsorbed by soil whether phosphate exists in soil or not. Phosphate can precipitate dramatically Nd3+. And the Nd phosphate precipitates may set limits on the concentration of exchangeable Nd observed in soil. KH2PO4 ranging from 0.3 g.kg-1 to 1.5 g.kg-1 make a uniform impact on the exchangeable form of Nd. In addition, phosphate in soil can inhibit wheat seedling to absorb Nd. The concentration of exchangeable Nd is correlated significantly with the content of Nd in wheat seedling.

Biological Availability↗

PubMed2001

[Effects of emodin on hepatic fibrosis in rats].

OBJECTIVE: To investigate the effect of emodin on hepatic fibrosis in rats and study its possible mechanism. METHODS: The rat hepatic fibrotic model was induced by the subcutaneous injection of 40% CCl(4) (twice a week for 6 weeks). The fibrotic rats were treated with low-dose, mediate-dose and high-dose emodin (20, 40 and 80 mg/kg body weight, once a day for 42 days). Liver function, serum hyaluronic acid, laminin, and liver hydroxyproline were determined, Histopathological changes were examined by optical microscopy. The expression of alpha-smooth muscle actin (alpha-SMA) in liver tissue were detected by immunohistochemical techniques. RESULTS: Compared with model group, it revealed that in emodin-treated rats: (1) Liver functions was improved, alanine transaminase (ALT) and alkaline phosphatase (AKP) obviously reduced (P<0.05 or <0.01), total protein (TP) and albumin (ALB) significantly increased (P<0.05 or <0.01). (2) Serum hyaluronic acid and laminin markedly reduced (P<0.05 or <0.01). (3) Liver hydroxyproline were significantly decreased (P<0.05 or <0.01). (4) The degrees of fibrosis were reduced (P<0.05). (5) The expression of alpha-SMA in liver tissue were ameliorated. CONCLUSIONS: Emodin has an effect on hepatic fibrosis in rats. The effect may be related to slowing hepatocyte injury and inhibiting liver alpha-SMA expressions.

Actins↗

PubMed2001

[Research of material bases on antifebrile and hypotensive effects of flos chrysanthemi].

OBJECTIVE: To study material bases on the antifebirle and hypotensive effect of Flos Chrysanthemi. METHODS: Temperature and blood pressure of rats were measured after treatment by taking several kinds of extracts of Flos Chrysanthemi. RESULTS: After volatile oil of Flos Chrysanthemi (0.8 ml/Kg) was taken by oral administration, temperature on the fever heat of rats could be decreased distinctly. After total flavonid of Flos Chrysanthemi (57 mg/Kg) was injected, blood pressure on rats could be reduced remarkly. CONCLUSION: Volatile oil of Flos Chrysanthemi has antifebrile effect and total flavonid of Flos Chrysanthemi has hypotensive effect, which are one of the Pharmacological bases of dispelling the wind-evil, clearing away the heat-evil, calming the liver, sharping eyes of Flos Chrysanthemi.

Animals↗

PubMed2001

Distribution of DT-diaphorase and reduced nicotinamide adenine dinucleotide phosphate: cytochrome p450 oxidoreductase in bladder tissues and tumors.

PURPOSE: We previously showed that mitomycin C activity in human bladder tumors is inversely related to tumor stage and muscle invasive tumors are less sensitive than superficial tumors. Because DT-diaphorase and reduced nicotinamide adenine dinucleotide phosphate:cytochrome P450 oxidoreductase (P450R) have a role in mitomycin C bioactivation, we investigated the distribution of these enzymes as a function of depth in the bladder wall and in human bladder tumors located at different parts of the bladder. MATERIALS AND METHODS: Gene expression of DT-diaphorase and P450R relative to the expression of beta-actin was measured by reverse transcriptase-polymerase chain reaction in 4 dog and 8 human bladder tissue specimens, and in 46 human bladder tumors. DT-diaphorase activity was measured by enzymatic assay in dog and human bladders. RESULTS: Data showed decreasing expression of DT-diaphorase and P450R from urothelium to muscle layer in the normal bladder wall with higher interindividual variation in humans than in dogs (greater than 40-fold versus approximately 3-fold). The expression of DT-diaphorase and P450R in bladder tumors correlated inversely with tumor stage (p <0.05) and was significantly higher in superficial than in muscle invasive bladder disease. DT-diaphorase and P450R expression in bladder tumors was approximately 6-fold higher than in normal bladder tissue. In normal and tumor tissues DT-diaphorase expression correlated significantly with P450R (r2 = 0.33, p <0.01), while DT-diaphorase expression correlated with its enzyme activity (r2 = 0.84, p <0.01). CONCLUSIONS: Our results indicate a higher distribution of DT-diaphorase and P450R in superficial bladder tumors and tissues. Preferential enzyme distribution in superficial tumors may be a cause of the higher efficacy of intravesical mitomycin C therapy for superficial versus muscle invasive disease.

Animals↗

PubMed2001

Microsatellite instability in thyroid cancer: hot spots, clinicopathological implications, and prognostic significance.

PURPOSE: To determine whether microsatellite instability (MSI) in particular loci has clinicopathological significance in thyroid cancer. EXPERIMENTAL DESIGN: Seventy-six cases of surgically resected thyroid cancer were screened for MSI at nine microsatellites: THRA1, TSHR, D2S123, D11S912, D2S115, D2S399, p53, RET, or BAT-26. Multivariate analysis was performed to test for links between MSI and the clinical parameters of gender, age, histology, stage, nodal involvement, and prognosis. RESULTS: THRA1, residing in the thyroid hormone receptor alpha gene, displayed the highest levels of MSI at 36.5%. MSI in TSHR, located within the thyroid-stimulating hormone receptor gene, was found to be linked to cancer in the elderly (>70 years of age) and with high-grade (N 3, 4) nodal involvement. In follicular cancer, MSI in D2S123 occurred at a frequency of 100% (7/7) with no (0%) occurrence of MSI at the nearby D2S115, D2S399, or BAT-26 loci. Regarding prognosis, patients with MSI-positive cancer showed better long-term survival. BAT-26, which is an important marker in colorectal cancer, displayed the lowest frequency of MSI in our panel of thyroid tumors. CONCLUSION: Whereas patients with MSI-positive cancer showed better long-term survival, as is the case for colorectal cancer, our finding of the low frequency of MSI in BAT-26 suggests that the biochemical defects governing the spectrum of MSI in thyroid and colorectal cancer are different. MSI in THRA1, TSHR, and D2S123 appears to be an integral part of thyroid carcinogenesis, as evidenced by the high frequency of MSI and significant correlation to clinical data.

Adult↗

PubMed2001

[Study on graft-versus-leukemia effects of donor lymphocyte infusion after nonmyeloablative allogeneic bone marrow transplantation].

OBJECTIVE: To explore the graft-versus-leukemia effects of donor lymphocyte infusion(DLI) after nonmyeloablative allogeneic bone marrow transplantation while attenuating treatment-associated morbidity, mortality and graft-versus-host disease. METHODS: 615(H-2k) mice were loaded with L615 cells and 3 days later received total body irradiation (TBI) 5 Gy (60 Co gamma-ray) followed by allogeneic bone marrow transplantation (allo-BMT). The allo-grafts consisted of 3 x 10(7) bone marrow cells and 1 x 10(7) spleen cells from BALB/c (H-2d) donor mice. Two days after allo-BMT, the recipient mice were given 200 mg/kg of CTX. Afterwards these recipient mice were infused either donor spleen cells (2 x 10(7)) on d14 and d21 or hydrocortison (HC) and cyclosporine A (CsA) treated donor spleen cells (5 x 10(7)) on d14 post-BMT. RESULTS: Survival time of mice received DLI on d21 and pretreated DLI on d14 post-BMT was longer than that of control group and d14 DLI group(P < 0.01) and without severe graft-versus-host disease. CONCLUSION: Donor lymphocyte infusion after nonmyeloablative bone marrow transplantation could reduce transplantation-associated morbidity and mortality while strengthening graft-versus-leukemia effects.

Animals↗