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Biomedical subjects

Qi Li

Publications and source records attributed to Qi Li.

At least 73 records · Page 4Linked to original sources
PubMed2006

[Anthropometry and female breast cancer: a prospective cohort study in urban Shanghai].

OBJECTIVE: To investigate the association between anthropometry and risk of breast cancer among pre-and post-menopausal women in urban Shanghai. METHODS: A total of 73 461 female residents aged 40 to 70 years in urban Shanghai were recruited in a prospective cohort study (the Shanghai women's health study) during 1997 through 2000, and were actively followed up biennially. During mean follow-up period of 5.66 years, 432 incident cases of breast cancer were identified in the cohort. Cox regression model was used to estimate the adjusted relative risks (RRs) and 95% confidence intervals (CIs). RESULTS: After adjustment for some potential confounding factors, baseline weight, body mass index(BMI), waist-to-hip ratio(WHR) and weight gain since age 20 were positively associated with the increased risk of breast cancer among postmenopausal women. The positive association between height and breast cancer was found among premenopausal women. Among them, those with height taller than 161 cm at age 20 experienced 1.84 fold increased risk (95% CI: 1.30-2.61) of breast cancer compared to their counterpart with height shorter than 157.1 cm. Women who were either much heavier or lighter than average at age 20 were at reduced risk. Further analyses mutually adjusted for BMI and WHR did not substantially alter the positive association for both BMI and WHR. After further adjustment for BMI, weight gain since age 20 was significantly associated to an increased risk for postmenopausal breast cancer (RR = 1.61, 95% CI: 1.09-2.37). CONCLUSIONS: Weight gain and central obesity seemed to be strong predictors for the risk of breast cancer among postmenopausal women. Controlling weight and decreasing fat around waist were effective means to prevent postmenopausal breast cancer and height might serve as a risk factor for premenopausal breast cancer.

Adult↗
PubMed2005

[Regulation of differentiation and proliferation of epiphysis stem cells by Notch1 signaling system].

OBJECTIVE: To investigate the regulation of differentiation and proliferation of epiphysis stem cells by Notch1 signaling system. METHODS: Costocostal cartilage was taken from a SD rat. Epiphysis stem cells were isolated and cultured. Recombinant human nuclear factor-kappaB (rhNF-kappaB), an activator of the Notch signaling system, and gamma-secretase inhibitor (MW167), an inhibitor of the Notch signaling system, were added into the culture medium respectively. The cells cultured in the medium added with phosphate-buffered saline were used as control group. Then the cultured cells were collected. The expression of the homologous Notch receptors and homologous Notch ligands was detected by RT-PCR. Immunohistochemistry was used to detect the levels of collagen II, collagen X, and proliferating cell nuclear antigen (PCNA). MTT method was used to calculate the growth curve. The cell phase was examined by flow cytometry. The level of alkaline phosphatase (AP) was measured. Western blotting was used to detect the protein expression of collagen II, collagen X, and stathmin, a signaling protein of proliferation. RESULTS: Only 2 the expression of the receptor Notch1 and the ligand Jagged1 was found. The expression of PCNA was stronger in the rhNF-kappaB group than in the other 2 groups. rhNF-kappaB remarkably promoted the expression of collagen II and inhibited the expression of collagen X and MW167 remarkably promoted the expression of collagen X and did not remarkably influence the expression of collagen II. MTT method showed that rhNF-kappaB significantly promote the proliferation of the cells (P = 0.027), and MW167 did not significantly promote the cell proliferation (P > 0.05). The percentage of cells at S phase of the rhNF-kappaB group was 26.54%, significantly higher than those of the MW167 group and control group (8.22% and 6.15%). AP was significantly expressed in the MW167 group, and less expressed in the other groups. Western blotting showed a significantly increased expression of collagen X protein and decreased expression of collagen II protein and stathmin. CONCLUSION: When the Notch signaling system is activated the epiphysis stem cells proliferate, and when the Notch signaling system is suppressed the epiphysis stem cells differentiate.

Animals↗
PubMed2005

The Shanghai Women's Health Study: rationale, study design, and baseline characteristics.

Although cancer is a major cause of morbidity and mortality in most nations, the spectrum of cancer occurrence varies substantially worldwide. Most previous epidemiologic studies investigating cancer etiology were conducted in North American and western European countries that are relatively homogenous in terms of cancer spectrums and many lifestyle exposures. These limitations may have hindered these studies from evaluating some important etiologic hypotheses. From 1996 to 2000, the Shanghai Women's Health Study recruited 74,942 adult Chinese women from selected urban communities, with a 92% response rate. All participants completed a detailed baseline survey and anthropometrics. Approximately 88% of cohort members donated a urine sample (n = 65,755) and a blood (n = 56,832) or exfoliated buccal cell (n = 8,934) sample. Noteworthy characteristics of this cohort include low consumption of alcohol (1.9%) and use of tobacco (2.4%); high intake of fish (mean, 50.8 g/day), soy foods (mean, 142.3 g/day), and certain vegetables; low prevalence of obesity (5.1%); and nearly 100% employment outside the home. Currently, this cohort of women is being followed via biennial in-person recontact and periodic linkage to cancer and vital statistics registries. The resources from the cohort will be valuable in future studies of environmental exposures and biomarkers for the risk of cancer and other chronic diseases.

Adult↗
PubMed2005

Heroin affects purine nucleotides catabolism in rats in vivo.

To investigate the effect of heroin on purine nucleotides catabolism, a rat model of heroin administration and withdrawal was established. Concentrations of uric acid, creatinine, and urea nitrogen in plasma and ADA in plasma, brain, liver, and small intestine were tested. When two heroin administration groups were compared with the control group, the concentrations of plasma uric acid and ADA in plasma, brain, liver, and small intestine increased, whereas the plasma urea nitrogen concentrations in two heroin administration groups and the plasma creatinine concentration in the 3-day heroin administration group did not increase. It seemed that heroin exposure for a short time did not affect renal clearance rate notably. When two withdrawal groups were compared with two heroin administration groups, the concentrations of plasma uric acid and ADA in liver and small intestine decreased, but there was no significant reduction in ADA concentrations of the brain, while the plasma ADA concentrations in the two withdrawal groups were significantly higher than those of two heroin administration groups. When the two withdrawal groups were compared with the control group, there was no significant difference in the concentrations of plasma uric acid and ADA in liver and small intestine, while the concentrations of ADA in plasma and brain were still higher than those of the control group. The results imply that heroin administration may enhance the catabolism of purine nucleotides in the brain and other tissues by increased concentration of ADA and the effect may last for a long time in the brain.

Adenosine Deaminase↗
PubMed2005

Prospective cohort study of soy food consumption and risk of bone fracture among postmenopausal women.

BACKGROUND: Soy consumption has been shown to modulate bone turnover and increase bone mineral density in postmenopausal women. To our knowledge, no published studies have directly examined the association between soy consumption and risk of fracture. METHODS: We examined the relationship between usual soy food consumption and fracture incidence in 24,403 postmenopausal women who had no history of fracture or cancer and were recruited between March 1, 1997, and May 23, 2000, in the Shanghai Women's Health Study, a cohort study of approximately 75,000 Chinese women aged 40 to 70 years. Usual soy food intake was assessed at baseline and reassessed during follow-up through in-person interviews using a validated food frequency questionnaire. Outcomes were ascertained by biennial in-person interview surveys. RESULTS: During a mean follow-up of 4(1/2) years (110,243 person-years), 1770 incident fractures were identified. After adjustment for age, major risk factors of osteoporosis, socioeconomic status, and other dietary factors, the relative risks (95% confidence intervals) of fracture were 1.00, 0.72 (0.62-0.83), 0.69 (0.59-0.80), 0.64 (0.55-0.76), and 0.63 (0.53-0.76) across quintiles of soy protein intake (P<.001 for trend). The inverse association was more pronounced among women in early menopause. The multivariate relative risks (95% confidence intervals) of fracture comparing the extreme quintiles of soy protein intake were 0.52 (0.38-0.70) for women within 10 years of menopause vs 0.71 (0.56-0.89) for late postmenopausal women. Similar results were also found for intake of isoflavones. CONCLUSION: Soy food consumption may reduce the risk of fracture in postmenopausal women, particularly among those in the early years following menopause.

Adult↗
PubMed2005

Segregation of microsatellite alleles in gynogenetic diploid Pacific abalone (Haliotis discus hannai).

Inheritance of 9 microsatellite loci was examined in 3 families of gynogenetic Pacific abalone Haliotis discus hannai produced by fertilizing eggs with UV-irradiated sperm followed by inhibition of the second meiotic division. The proportion of heterozygous progeny was used to estimate marker-centromere (M-C) distances. All loci conformed to Mendelian segregation in the control crosses when null alleles were accounted for. The absence of paternal alleles confirmed the gynogenetic origin of the offspring and indicated 100% success for 3 families. Estimated recombinant frequencies ranged from 0.10 to 0.60, which is lower than those observed in other gynogenetic diploid animals. The mean recombination frequency was 0.22, corresponding to a fixation index of 0.78 in one generation. This is 3.12 times the increase in homozygosity expected after one generation of sib mating (0.25), suggesting meiotic gynogenesis may be an effective means of rapid inbreeding in the abalone. M-C map distances for the 9 loci varied between 5 and 30 cM under the assumption of complete interference. The information about M-C distances will be useful for future gene mapping in H. discus hannai.

Animals↗
PubMed2005

Isolation and characterization of twenty microsatellite loci in Japanese sea cucumber (Stichopus japonicus).

Twenty microsatellite markers were first developed from the Japanese sea cucumber Stichopus japonicus using an enrichment protocol. Of the 20 microsatellite loci, 19 loci were polymorphic in the population examined. At these polymorphic loci, the number of alleles per locus varied from 2 to 15, and the observed heterozygosities ranged from 0.03 to 0.97, which is considerably higher than those previously found for allozymes. The high variability of the microsatellite markers identified in this study will make them excellent tools for genetic analyses of S. japonicus.

Animals↗
PubMed2005

Association of passive smoking by husbands with prevalence of stroke among Chinese women nonsmokers.

Growing evidence suggests that exposure to environmental tobacco smoke may have deleterious cardiovascular effects. Few studies have investigated environmental tobacco smoke exposure in relation to stroke. The authors examined the association between smoking by husbands and stroke prevalence among women nonsmokers in Shanghai, China, where two thirds of men but few women smoke. They analyzed baseline survey data (1997-2000) from a population-based cohort study, the Shanghai Women's Health Study. A total of 60,377 eligible women (aged 40-70 years) were included in the analysis. Information on husbands' smoking status and history of physician-diagnosed stroke was obtained through in-person interviews. Logistic regression was used to compute odds ratios for the associations. There were 526 prevalent cases of stroke reported. The adjusted odds ratios of stroke in women associated with husbands' current smoking of 1-9, 10-19, and > or =20 cigarettes per day were 1.28 (95% confidence interval: 0.92, 1.77), 1.32 (95% confidence interval: 1.01, 1.72), and 1.62 (95% confidence interval: 1.28, 2.05), respectively (p for trend = 0.0002). Prevalence of stroke also increased with increasing duration of husbands' smoking. The authors found that women nonsmokers who lived with husbands who smoked had an elevated prevalence of stroke, and prevalence increased with increasing intensity and duration of husbands' smoking.

Adult↗
PubMed2005

Microemulsion and micellar electrokinetic chromatography of Hematoporphyrin D: a starting material of hematoporphyrin derivative.

An investigation of the basic factors which govern the microemulsion electrokinetic chromatography (MEEKC) and micellar electrokinetic chromatography (MEKC) separation of Hematoporphyrin D and its base hydrolysis product, hematoporphyrin derivative (HpD), was performed. These model compounds contain a complex mixture of porphyrin monomers, dimers and/or oligomers, and were utilized to gain insights into the MEEKC/micellar electrokinetic chromatography (MEKC) separation of samples containing highly lipophilic substances. For example, the organic modifier/cosurfactant (1-butanol) and/or oil phase (e.g., 1-octanol in comparison to ethyl acetate) were found to have an apparent influence on the separation selectivity of Hematoporphyrin D, the extent of which was dependent on the chemical nature of the surfactant employed (e.g., sodium dodecyl sulfate vs. sodium cholate). An interesting and important finding was that the presence of an organic modifier (methanol or acetonitrile at a concentration of 20% or higher) in the sample matrix as well as in the run buffer was essential for the optimal MEEKC or MEKC separation of a number of porphyrin monomers (including hematoporphyrin IX and its acetates, most likely hydroxyacetate, diacetate, and vinyl acetate, as well as its dehydration products, hydroxyethylvinyldeuteroporphyrin and protoporphyrin) contained in Hematoporphyrin D. On the other hand, the use of these optimized conditions for the MEEKC or MEKC separation of various oligomeric porphyrin species in HpD were unsatisfactory. As HpD is a well-known and effective photosensitizing agent in photodynamic therapy (a new approach for cancer treatment), the improved separation and characterization of various monomeric and oligomeric porphyrin species in HpD and its starting material, such as Hematoporphyrin D, is a challenging and important task.

1-Butanol↗
PubMed2005

Investigation of solvent effects in capillary electrophoresis for the separation of biological porphyrin methyl esters.

The effects of organic solvents on the capillary electrophoresis (CE) separation of a number of important biological porphyrin methyl esters - six weakly basic, hydrophobic cyclic tetrapyrroles possessing two and four to eight methyl ester groups around the periphery of the porphyrin ring - were investigated in the mode of micellar electrokinetic chromatography (MEKC), microemulsion electrokinetic chromatography (MEEKC), and nonaqueous CE. In aqueous MEKC, partial separation of the six neutral porphyrin methyl esters was obtained with an organic modifier (acetonitrile) in the concentration range between 20 and 40%, in which sodium dodecyl sulfate (SDS) molecules might be present in the form of SDS micelles and/or SDS micelle-like aggregates. Relatively stable SDS micelles can be formed in nonaqueous MEKC using formamide as the separation medium, but the separation of the target analytes remained unsatisfactory. Improved resolution of all six porphyrin methyl esters was obtained using MEEKC with the running buffer consisting of 0.8% w/w n-heptane (oil phase), 2.25% w/w SDS and 1.0% w/w Brij 35 (mixed surfactant), 6.6% w/w 1-butanol (cosurfactant), and 30% v/v 2-propanol (second cosurfactant), but reproducibility in terms of peak areas for certain porphyrins (especially uroporphyrin I octamethyl ester) was found to be very poor. Best separation performances were achieved with nonaqueous CE separations in which the weakly basic porphyrin methyl esters were protonated under strongly acidic conditions (e.g., using 10 mM perchloric acid) in mixed organic solvents. For example, using a 50:50 mixture of methanol and acetonitrile as the separation medium, baseline separation of all six (positively charged) porphyrin methyl esters can be obtained within 3 min and the average precision (RSD, N = 13) in terms of migration time and peak area were 0.55 and 2.16%, respectively.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2005

Effects of slow-release urea fertilizers on urease activity, microbial biomass, and nematode communities in an aquic brown soil.

A field experiment was carried out at the Shenyang Experimental Station of Ecology (CAS) in order to study the effects of slow-release urea fertilizers high polymer-coated urea (SRU1), SRU1 mixed with dicyandiamide DCD (SRU2), and SRU1 mixed with calcium carbide CaC2 (SRU3) on urease activity, microbial biomass C and N, and nematode communities in an aquic brown soil during the maize growth period. The results demonstrated that the application of slow-release urea fertilizers inhibits soil urease activity and increases the soil NH4+-N content. Soil available N increment could promote its immobilization by microorganisms. Determination of soil microbial biomass N indicated that a combined application of coated urea and nitrification inhibitors increased the soil active N pool. The population of predators/omnivores indicated that treatment with SRU2 could provide enough soil NH4+-N to promote maize growth and increased the food resource for the soil fauna compared with the other treatments.

Acetylene↗
PubMed2005

Using qualitative studies to improve the usability of an EMR.

The adoption of electronic medical records (EMRs) and user satisfaction are closely associated with the system's usability. To improve the usability of a results management module of a widely deployed web-based EMR, we conducted two qualitative studies that included multiple focus group and field study sessions. Qualitative research can help focus attention on user tasks and goals and identify patterns of care that can be visualized through task modeling exercises. Findings from both studies raised issues with the amount and organization of information in the display, interference with workflow patterns of primary care physicians, and the availability of visual cues and feedback. We used the findings of these studies to recommend design changes to the user interface of the results management module.

Attitude to Computers↗
PubMed2005

Penetrating the oxide barrier in situ and separating freestanding porous anodic alumina films in one step.

A simple method for penetrating the barrier layer of an anodic aluminum oxide (AAO) film and for detaching the AAO film from residual Al foil was developed by reversing the bias voltage in situ after the anodization process is completed. With this technique, we have been able to obtain large pieces of free-standing AAO membranes with regular pore sizes of sub-10 nm. By combining Ar ion milling and wetting enhancement processes, Au nanowires were grown in the sub-10 nm pores of the AAO films. Further scaling down of the pore size and extension to the deposition of nanowires and nanotubes of materials other than Au should be possible by further optimizing this procedure.

Journal Article↗
PubMed2005

Longitudinal study of soy food intake and blood pressure among middle-aged and elderly Chinese women.

BACKGROUND: Several small-scale clinical trials have suggested a potential beneficial effect of short-term soy consumption on blood pressure (BP). Data are scanty on long-term effects of the usual intake of soy foods on BP in general populations. OBJECTIVE: Our aim was to examine the association between usual intake of soy foods and BP. DESIGN: The usual intake of soy foods was assessed at baseline, and BP was measured 2-3 y after the baseline survey among 45 694 participants of the Shanghai Women's Health Study aged 40-70 y who had no history of hypertension, diabetes, or cardiovascular disease at recruitment. Multiple regression models were used to estimate mean differences in BP associated with various intakes of soy foods. RESULTS: Soy protein intake was inversely associated with both systolic BP (P for trend = 0.01) and diastolic BP (P for trend = 0.009) after adjustment for age, body mass index, and lifestyle and other dietary factors. The adjusted mean systolic BP was 1.9 mm Hg lower (95% CI: -3.0, -0.8 mm Hg) and the diastolic BP was 0.9 mm Hg lower (-1.6, -0.2 mm Hg) in women who consumed > or =25 g soy protein/d than in women consuming <2.5 g/d. The inverse associations became stronger with increasing age (P for interaction < 0.05 for both BPs). Among women >60 y old, the corresponding differences were -4.9 mm Hg (95% CI: -8.0, -1.9 mm Hg) for systolic BP and -2.2 mm Hg (95% CI: -3.8, -0.6 mm Hg) for diastolic BP. CONCLUSION: Usual intake of soy foods was inversely associated with both systolic and diastolic BPs, particularly among elderly women.

Adult↗
PubMed2005

A fuzzy-based approach to remove clock skew and reset from one-way delay measurement.

One-way delay (OWD) traces are important measurements for analyzing end-to-end performance on the Internet. It is still a great challenge to provide a scalable solution for large-scale OWD measurement. Because the clocks at end systems are usually not synchronized, the OWD measurements are often inaccurate. For the more challenging case with clock resets to some reference times during the measurement, the OWD measurements are more inaccurate. Furthermore, the measurement data often exhibit considerable network-induced noise when the network is heavily loaded. All the existing OWD measurement techniques, such as linear programming and convex-hull approach (CHA), try to solve this problem by deterministic mathematics model. However, they often fail to distinguish clock resets from temporary Internet congestion. Based on the fuzzy-clustering analysis, this paper proposes a new algorithm to estimate and remove the clock skews and resets from measurement results. This algorithm has been implemented as a tool called fuzzy-based OWD corrector (FOC). The paper then presents OWD measurements of several Internet paths using FOC. Numerical experiments demonstrate that FOC is more accurate and robust than the existing techniques. FOCs computation complexity O(N) is similar to that of CHA and its computing time is much less than that of convex-hull technique.

Algorithms↗
PubMed2005

A two-stage linear discriminant analysis via QR-decomposition.

Linear Discriminant Analysis (LDA) is a well-known method for feature extraction and dimension reduction. It has been used widely in many applications involving high-dimensional data, such as image and text classification. An intrinsic limitation of classical LDA is the so-called singularity problems; that is, it fails when all scatter matrices are singular. Many LDA extensions were proposed in the past to overcome the singularity problems. Among these extensions, PCA+LDA, a two-stage method, received relatively more attention. In PCA+LDA, the LDA stage is preceded by an intermediate dimension reduction stage using Principal Component Analysis (PCA). Most previous LDA extensions are computationally expensive, and not scalable, due to the use of Singular Value Decomposition or Generalized Singular Value Decomposition. In this paper, we propose a two-stage LDA method, namely LDA/QR, which aims to overcome the singularity problems of classical LDA, while achieving efficiency and scalability simultaneously. The key difference between LDA/QR and PCA+LDA lies in the first stage, where LDA/QR applies QR decomposition to a small matrix involving the class centroids, while PCA+LDA applies PCA to the total scatter matrix involving all training data points. We further justify the proposed algorithm by showing the relationship among LDA/QR and previous LDA methods. Extensive experiments on face images and text documents are presented to show the effectiveness of the proposed algorithm.

Algorithms↗
PubMed2005

Lymphoid neogenesis in murine cardiac allografts undergoing chronic rejection.

Lymphoid neogenesis is the process by which ectopic lymphoid accumulations that resemble lymph nodes arise in nonlymphoid tissues. Such lymphoid accumulations, known as tertiary lymphoid organs (TLO), are observed in chronic autoimmunity and they propagate immune pathology by setting up local antigen presenting sites. Whether lymphoid neogenesis occurs in transplanted organs and contributes to rejection is not well understood. To begin to address this question, we retrospectively analyzed 319 murine cardiac allografts for microscopic evidence of lymph-node-like structures. We found 78 allografts that had either classical TLO, characterized by discrete T- and B-cell zones and high endothelial venules (HEV) expressing peripheral node addressin (PNAd) (n = 34), or PNAd(+) HEV without organized lymphoid accumulations (n = 44). These changes were present in both short- and long-lived allografts and were invariably associated with rejection. Importantly, they occurred in 78% of allografts undergoing chronic rejection (n = 85) but in only 7% of allografts undergoing primarily acute rejection (n = 184). These findings indicate that, like autoimmunity, alloimmunity is associated with lymphoid neogenesis in the target organ and suggest a role for local T-cell activation in chronic allograft rejection.

Animals↗