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Biomedical subjects

Li Qin

Publications and source records attributed to Li Qin.

At least 19 recordsLinked to original sources
PubMed2025

Inactivation of β-1,3-glucan synthase-like 5 confers broad-spectrum resistance to Plasmodiophora brassicae pathotypes in cruciferous plants.

Clubroot disease, caused by the obligate intracellular rhizarian protist Plasmodiophora brassicae, is devastating to cruciferous crops worldwide. Widespread field P. brassicae pathotypes frequently overcome the pathotype-specific resistance of modern varieties, posing a challenge for durable control of this disease. Here a genome-wide association study of 3 years of data comprising field clubroot phenotyping of 244 genome-resequenced Brassica napus accessions identified a strong association of β-1,3-glucan synthase-like 5 (GSL5) with clubroot susceptibility. GSL5 was evolutionarily conserved, and inactivation of GSL5 by genome editing in Arabidopsis, B. napus, Brassica rapa and Brassica oleracea conferred broad-spectrum, high-level resistance to P. brassicae pathotypes without yield penalties in B. napus. GSL5 inactivation derepressed the jasmonic acid-mediated immunity during P. brassicae secondary infection, and this immune repression was possibly reinforced through stabilization of GSL5 by a P. brassicae effector, facilitating clubroot susceptibility. Our study provides durable resistance resources for cruciferous clubroot disease control and insights into plant resistance against intracellular eukaryotic phytopathogens.

Disease Resistance↗
PubMed2025

Natural self-attenuation of pathogenic viruses by deleting the silencing suppressor coding sequence for long-term plant-virus coexistence.

Potyviridae is the largest family of plant-infecting RNA viruses. All members of the family (potyvirids) have single-stranded positive-sense RNA genomes, with polyprotein processing as the expression strategy. The 5'-proximal regions of all potyvirids, except bymoviruses, encode two types of leader proteases: the serine protease P1 and the cysteine protease HCPro. However, their arrangement and sequence composition vary greatly among genera or even species. The leader proteases play multiple important roles in different potyvirid-host combinations, including RNA silencing suppression and virus transmission. Here, we report that viruses in the genus Arepavirus, which encode two HCPro leader proteases in tandem (HCPro1-HCPro2), can naturally lose the coding sequences for these two proteins during infection. Notably, this loss is associated with a shift in foliage symptoms from severe necrosis to mild chlorosis or even asymptomatic infections. Further analysis revealed that the deleted region is flanked by two short repeated sequences in the parental isolates, suggesting that recombination during virus replication likely drives this genomic deletion. Reverse genetic approaches confirmed that the loss of leader proteases weakens RNA silencing suppression and other critical functions. A field survey of areca palm trees displaying varied symptom severity identified a transitional stage in which full-length viruses and deletion mutants coexist in the same tree. Based on these findings, we propose a scenario in which full-length isolates drive robust infections and facilitate plant-to-plant transmission, eventually giving rise to leader protease-less variants that mitigate excessive damage to host trees, allowing long-term coexistence with the perennial host. To our knowledge, this is the first report of potyvirid self-attenuation via coding sequence loss.

Plant Diseases↗
PubMed2006

Ga-assisted synthesis and optical properties of ZnO submicron- and nanotowers.

Tower-like ZnO submicron- and nanostructures were synthesized by simply evaporating a mixture of Zn and Ga. Scanning electron microscopy and transmission electron microscopy observations showed that the regular hexagonal tower-like structure is likely to be made up in a layer-by-layer fashion and consist of sheets. According to our experiments, the amount of Ga has a large effect on their morphologies. The growth of such tower-like structures is ascribed to the vapor-solid mechanism. The introduction of Ga hinders the growth of ZnO along the [0001] direction, resulting in the formation of the novel tower-like structures. In addition, the photoluminescence of such structures shows a strong green-light emission.

Journal Article↗
PubMed2006

Informal caregiver burden among survivors of prolonged mechanical ventilation.

RATIONALE: Although caregiver burden is well described in chronic illness, few studies have examined burden among caregivers of survivors of critical illness. In existing studies, it is unclear whether the observed burden is a consequence of critical illness or of preexisting patient illness. OBJECTIVES: To describe 1-yr longitudinal outcomes for caregivers of patients who survived critical illness, and to compare depression risk between caregivers of patients with and without pre-intensive care unit (ICU) functional dependency. METHODS: Prospective, parallel, cohort study of survivors of prolonged (greater than 48 h) mechanical ventilation and their informal caregivers. Caregivers were divided into two cohorts on the basis of whether patients were functionally independent (n = 99, 59%), or dependent (n = 70, 41%) before admission. Functional dependency was defined as dependency in one or more activities of daily living or in three or more instrumental activities of daily living. Patient and caregiver outcomes were measured 2, 6, and 12 mo after mechanical ventilation initiation. MEASUREMENTS AND MAIN RESULTS: We studied three caregiver outcomes: depression risk, lifestyle disruption, and employment reduction. Most patients were male (59.8%), with a mean (SD) age of 56.6 (19.0) yr. Caregivers were mostly female (75.7%), with a mean (SD) age of 54.6 (14.7) yr. Prevalence of caregiver depression risk was high at all time points (33.9, 30.8, and 22.8%; p = 0.83) and did not vary by patient pre-ICU functional status. Lifestyle disruption and employment reduction were also common and persistent. CONCLUSIONS: Depression symptoms, lifestyle disruption, and employment reduction were common among informal caregivers of critical illness survivors. Depression risk was high regardless of patient pre-ICU functional status.

Caregivers↗
PubMed2006

Stable RNA interference of ErbB-2 gene synergistic with epirubicin suppresses breast cancer growth in vitro and in vivo.

Overexpression of human epidermal growth factor receptor-2 (Her2, ErbB-2) contributes to the progression and metastasis of breast cancer, implying that Her2 gene is a suitable target of RNA interference (RNAi) for breast cancer therapy. Here, we employed plasmid-mediated expression of 2 different Her2-shRNAs (pU6-Her2shRNAs) efficiently silenced the target gene expression on Her2 expressing SKBR-3 breast cancer cells in both mRNA and protein levels. Consequently, pU6-Her2shRNA increased apoptosis and reduced proliferation of SKBR-3 cells assayed by TUNEL and MTT, respectively. In vivo, intra-tumor injection of pU6-Her2shRNA inhibited the growth of SKBR-3 tumors inoculated subcutaneously in nude mice. Furthermore, pU6-Her2shRNA synergized the tumor suppression effect of epirubicin to SKBR-3 cells in vitro and implanted subcutaneously in nude mice. Therefore, we concluded that stable silencing of Her2 gene expression with plasmid expressing shRNA may hold great promise as a novel therapy for Her2 expressing breast cancers alone or in combination with anthracycline chemotherapy.

Animals↗
PubMed2006

[Effect of pravastatin on cholesteryl esters in foam cells and the relation with caveolin-1].

The purpose of the present study was to investigate the effect of pravastatin on cholesteryl esters in foam cells of murine macrophages and the relation with caveolin-1. RAW 264.7 murine macrophages were coincubated with 80 mg/L oxidized low density lipoprotein (ox-LDL) and pravastatin (0~100 mumol/L) respectively for 24 h. When the best control concentration of pravastatin was confirmed, RAW 264.7 murine macrophages were coincubated with 80 mg/L ox-LDL and pravastatin of the best concentration respectively for 0, 6, 12, 24 h. Oil red O dyeing experiment was used to show the lipid droplets in foam cells. High performance liquid chromatography (HPLC) analysis was performed to determine the content of cellular cholesterol. The level of caveolin-1 was determined by Western blot analysis. The result showed that when macrophages were incubated with 80 mg/L ox-LDL, the ratio of cellular cholesteryl ester to total cholesterol (CE/TC) was beyond 50% through HPLC analysis, and a great deal of lipid droplets displayed in cells through Oil red O dyeing experiment, which manifested the formation of the foam cells. Pravastatin could decrease CE in foam cells in a concentration-dependent manner (1~100 mumol/L). At the concentration of 100 mumol/L, pravastatin decreased cellular CE more than 50%. The effects of pravastatin on the decrease of CE in murine macrophages also displayed a time-dependent manner (incubated with 100 mumol/L pravastatin from 6 to 24 h). Moreover, the expression of caveolin-1 was decreased when the macrophages were incubated with ox-LDL (80 mg/L), while treatment with pravastatin increased the level of caveolin-1 and displayed a concentration- and time-dependent manner. These results suggest that pravastatin could inhibit the development of foam cells through the decrease of cellular CE, which may be related to the upregulation of caveolin-1.

Animals↗
PubMed2006

A double-blind randomized controlled trial of toremifen therapy for mastalgia.

HYPOTHESIS: Toremifen is effective in reducing breast pain and does not increase the incidence of adverse events as a therapy for moderate to severe mastalgia. DESIGN AND PATIENTS: In a double-blind randomized controlled trial, patients with moderate to severe mastalgia received toremifen citrate, 30 mg daily, or a placebo tablet for 3 menstrual cycles and were followed up for breast pain score and adverse events. The serum levels of estradiol, progesterone, and prolactin were examined before treatment and correlated with the response rate to toremifen treatment. RESULTS: Seventy-two (69.2%) of 104 patients receiving toremifen and 29 (31.9%) of 91 receiving placebo responded to the treatment, with reduction in breast pain score of more than 50% (P<.001). Among the patients with cyclical mastalgia, the response rate for toremifen was 76.7% (59/77), whereas the response rate for placebo was 34.8% (23/66; P<.001). In contrast, the response rate of patients with noncyclical mastalgia was 48.1% (13/27) for toremifen and 24.0% (6/25) for placebo (P = .09). Adverse events were observed in 44 (42.9%) of 104 patients receiving placebo and 46 (50.5%) of 91 patients receiving toremifen (P = .45). A positive correlation between baseline breast pain score and serum estradiol level was observed in patients with cyclical mastalgia (r = 0.35, P = .003). CONCLUSIONS: Toremifen effectively relieves moderate and severe cyclical mastalgia and tends to exert a positive therapeutic effect on noncyclical mastalgia. In addition, toremifen therapy does not increase the incidence of intolerable adverse event. Therefore, it is a feasible therapy for mastalgia, especially cyclical mastalgia.

Breast Diseases↗
PubMed2006

A predictive model for the detection of tumor lysis syndrome during AML induction therapy.

Tumor lysis syndrome (TLS) is defined by metabolic derangements occurring in the setting of rapid tumor destruction. In acute myelogenous leukemia (AML), TLS frequency, risk stratification, monitoring, and management strategies are based largely on case series and data from other malignancies. A single-center, retrospective cohort study was conducted to estimate TLS incidence and identify TLS predictive factors in a patient population undergoing myeloid leukemia induction chemotherapy. This study included 194 patients, aged 18-86 years, with AML or advanced myelodysplastic syndrome undergoing primary myeloid leukemia induction chemotherapy. Nineteen patients (9.8%) developed TLS. In univariate analysis, elevated pre-chemotherapy values for uric acid (P < 0.0001), creatinine (P = 0.0025), lactate dehydrogenase (LDH) (P = 0.0001), white blood cell (P = 0.0058), gender (P = 0.0064) and chronic myelomonocytic leukemia history (P = 0.0292) were significant predictors. In multivariate analysis, LDH (P = 0.0042), uric acid (P < 0.0001) and gender (P = 0.0073) remained significant TLS predictors. A predictive model was then designed using a scoring system based on these factors. This analysis may lay the groundwork for the development of the first evidence-based guidelines for TLS monitoring and management in this patient population.

Adolescent↗
PubMed2006

Atomic force microscopy-based cell nanostructure for ligand-conjugated quantum dot endocytosis.

While it has been well demonstrated that quantum dots (QDs) play an important role in biological labeling both in vitro and in vivo, there is no report describing the cellular nanostructure basis of receptor-mediated endocytosis. Here, nanostructure evolution responses to the endocytosis of transferrin (Tf)-conjugated QDs were characterized by atomic force microscopy (AFM). AFM-based nanostructure analysis demonstrated that the Tf-conjugated QDs were specifically and tightly bound to the cell receptors and the nanostructure evolution is highly correlated with the cell membrane receptor-mediated transduction. Consistently, confocal microscopic and flow cytometry results have demonstrated the specificity and dynamic property of Tf-QD binding and internalization. We found that the internalization of Tf-QD is linearly related to time. Moreover, while the nanoparticles on the cell membrane increased, the endocytosis was still very active, suggesting that QD nanoparticles did not interfere sterically with the binding and function of receptors. Therefore, ligand-conjugated QDs are potentially useful in biological labeling of cells at a nanometer scale.

Cell Line, Tumor↗
PubMed2006

Weight concerns affect motivation to remain abstinent from smoking postpartum.

BACKGROUND: Although many women quit smoking during pregnancy, most resume smoking postpartum. One factor that may be important in postpartum relapse is a pregnant woman's motivation to remain abstinent after delivery. PURPOSE: We assessed motivation for postpartum abstinence among pregnant women who had quit smoking and examined the relationship of weight concerns and mood to abstinence motivation. METHODS: Pregnant former smokers, recruited between February 2000 and November 2004, completed assessments of smoking, weight concerns, depressive symptoms, and perceived stress. RESULTS: Sixty-five percent were highly motivated to remain abstinent postpartum. Women who were and were not motivated were similar in age, race, and nicotine dependence. However, motivated women reported more stress, greater self-efficacy for weight management, less hunger, and less smoking for weight control than did less motivated women. After controlling for intention to breast-feed, nicotine dependence, years of smoking, partner smoking, and race, self-efficacy for weight control was related to motivation to maintain postpartum abstinence. CONCLUSIONS: These data suggest that weight concerns are associated with motivation for postpartum smoking abstinence, and interventions designed to prevent postpartum smoking relapse may need to target eating, weight, and shape concerns.

Adult↗
PubMed2006

[A reverse transcriptase-polymerase chain reaction method improving the specific amplification of caveolin-1 gene sequences].

OBJECTIVE: To construct a reverse transcriptase-polymerase chain reaction (RT-PCR)approach that can improve the specificity of primers while dropping down the nonspecific amplification. METHODS: In the recent study we reported a new RT-PCR assay which improved markedly the specificity. However its efficiency of regressing nonspecific amplification remains to be accurately checked and further documented. In primer design, we looked over again some sequences that showed differences at 5' or 3' ends between human CAV1 and mouse Cav1 genes. cDNAs and the diluted plasmids which harbored the sequence of human CAV1 or mouse Cav1 gene were chosen as the templates. The ordinary PCR compared with one, of which primers modified by phosphorothioate and combined with proofreading polymerase, for their efficiencies of nonspecific amplification inhibited. RESULTS: Taq DNA polymerase without proofreading activity could efficiently catalyze the extension of primers with a single or multiple mismatched base pairs at the 3' terminus, but the kind of primer extension can be effectively blocked by phosphorothioate modified primers combined with proofreading polymerase. Compared with ordinary PCR reaction, this new PCR method can effectively regress the primer mismatched amplification of 50 ng DNA almost equaling to 2 x 10(4) unmatched template copies in a final volume of 50 microL. CONCLUSION: Compared with the first generation of polymerases with or without proofreading activities mediating RT-PCR reaction, the introduction of nuclease-resistant 3' modified primers (3' phosphorothioate primer extension) can offer more simplicity, accuracy, and also decrease cost.

Animals↗
PubMed2006

[Vector-mediated HER-2 RNA interference against HER-2-positive breast cancer].

OBJECTIVE: To study the feasibility of vector-mediated RNA interference for HER-2-positive breast cancer therapy. METHODS: A plasmid vector capable of mediating HER-2 RNA interference was constructed, and HER-2-positive breast cancer cell line SKBR-3 was transfected with this constructed vector. The expression of HER-2 mRNA and protein was analyzed by RT-PCR and Western blotting, and the growth and apoptosis of SKBR-3 cells was analyzed after transfection. RESULTS: The expressions of HER-2 mRNA and HER-2 protein was downregulated in response to vector-mediated HER-2 RNA interference, which also resulted in tumor cell growth inhibition and increased number apoptotic cells. CONCLUSION: HER-2 is a good target for RNA interference and RNA interference targeting HER-2 can lead to HER-2 breast cancer cell apoptosis and growth inhibition.

Apoptosis↗
PubMed2006

[Determination of trace copper and cadmium in water by flame atomic absorption spectrometry coupled with flow injection on-line preconcentration using air segmentation].

The flow injection on-line preconcentration with a knotted reactor (KR) system for the determination of copper and cadmium in water by flame atomic absorption spectrometry (FAAS) was described in the present paper. The precipitation preconcentration of trace copper and cadmium was achieved by on-line merging of the sample and ammonia solutions. The resultant precipitates were on-line collected by a knotted reactor (KR) without filtration, and then the authors used a process of air segmentation. A solution of 1 mol x L(-1) HNO3 was employed to dissolve the collected precipitates and to deliver the analyte into the FAAS system for on-line detection. With a sample loading flow rate of 4.4 mL x min(-1) and a preconcentration time of 90 s, the enhancement factor was 34 (for Cu) and 36 (for Cd) as compared with the conventional FAAS method. The detection limits (3sigma) are found to be 1.9 and 0.3 microg x L(-1) for copper and cadmium respectively. The precision (RSD, n = 11) was found to be 2.3% at the level of 30.0 microg x L(-1) of Cu (II), and 2.6% at the level of 20.0 microg x L(-1) of Cd (II). The proposed method has been successfully applied to the determination of Cu (II) and Cd (II) in water samples.

Cadmium↗
PubMed2005

[Expression and purification of Toxoplasma gondii GRA4 gene in prokaryotic system].

OBJECTIVE: To construct a prokaryotic expression system containing the dense granule protein 4 (GRA4) of Toxoplasma gondii, purify the expressed protein and detect its immunogenicity. METHODS: The specific fragment of GRA4 gene was amplified by PCR. After subcloning the prokaryotic expression recombinant pET-GRA4, the expressed product was purified with His Bind affinity chromatography and analyzed by Western blot. BALB/c mice were immunized with the GRA4 recombinant protein, and the antibody IgG titer was detected by ELISA. RESULTS: The pET-GRA4 prokaryotic expression system was obtained. The MW of the expressed protein was Mr 40,000 and formed in inclusion body. After purification, the recombinant protein could be specifically recognized by the T. gondii infected rabbit serum. Mice immunized with the purified recombinant protein elicited high titer of IgG antibody. CONCLUSION: The pET-GRA4 recombinant protein was successfully expressed and purified, which shows the immunogenicity.

Animals↗
PubMed2005

Functional mixed-effects model for periodic data.

Periodic data are frequently collected in biomedical experiments. We consider the underlying periodic curves giving rise to these data, and account for the periodicity in their functional model to improve estimation and inference. We propose to incorporate the periodic constraint in the functional mixed-effects model setting. Both the fixed functional effects and random functional effects are modeled in the same periodic functional space, hence the population-average estimates and subject-specific predictions are all periodic. An efficient algorithm is given to estimate the proposed model by an O(N) modified Kalman filtering and smoothing algorithm. The proposed method is evaluated in different scenarios through simulations. Treatments to none-full period data and missing observations along the period are also given. Analysis of a cortisol data set obtained from a study on fibromyalgia is conducted as illustration.

Algorithms↗
PubMed2005

Similar long-term results of breast-conservation treatment for Stage I and II invasive lobular carcinoma compared with invasive ductal carcinoma of the breast: The University of Pennsylvania experience.

BACKGROUND: The objective of the current study was to determine the long-term results of breast-conservation treatment in women with early-stage, invasive lobular carcinoma of the breast. METHODS: Between 1977 and 1995, 1093 women with Stage I and II invasive ductal carcinoma of the breast and 55 women with invasive lobular carcinoma of the breast underwent lumpectomy, axillary lymph node dissection, and radiation treatment. Overall, 49% of the women received adjuvant systemic therapy (chemotherapy and/or hormones). RESULTS: The median age was 52 years for patients in the invasive ductal group and 54 years for patients in the invasive lobular group. The median follow-up was 8.7 years and 10.2 years for patients in the invasive ductal and invasive lobular groups, respectively. A comparison of patients who had invasive lobular carcinoma with patients who had invasive ductal carcinoma showed no difference in the 10-year actuarial rates of overall survival (85% vs. 79%, respectively; P = 0.73), cause-specific survival (93% vs. 84%, respectively; P = 0.85), or freedom from distant metastases (81% vs. 80%, respectively; P = 0.76). The 10-year rates of local failure were 18% for patients with invasive lobular carcinoma and 12% for patients with invasive ductal carcinoma (P = 0.24), and the 10-year rates of contralateral breast carcinoma development for the 2 groups were 12% and 8%, respectively (P = 0.40). CONCLUSIONS: Breast-conservation treatment yielded similar long-term results for women with early-stage, invasive lobular carcinoma and women with the more prevalent invasive ductal carcinoma.

Adult↗
PubMed2005

L-DOPA reverses the MPTP-induced elevation of the arrestin2 and GRK6 expression and enhanced ERK activation in monkey brain.

Dysregulation of dopamine receptors (DARs) is believed to contribute to Parkinson disease (PD) pathology. G protein-coupled receptors (GPCR) undergo desensitization via activation-dependent phosphorylation by G protein-coupled receptor kinases (GRKs) followed by arrestin binding. Using quantitative Western blotting, we detected profound differences in the expression of arrestin2 and GRKs among four experimental groups of nonhuman primates: (1) normal, (2) parkinsonian, (3) parkinsonian treated with levodopa without or (4) with dyskinesia. Arrestin2 and GRK6 expression was significantly elevated in the MPTP-lesioned group in most brain regions; GRK2 was increased in caudal caudate and internal globus pallidus. Neither levodopa-treated group differed significantly from control. The only dyskinesia-specific change was an elevation of GRK3 in the ventral striatum of the dyskinetic group. Changes in arrestin and GRK expression in the MPTP group were accompanied by enhanced ERK activation and elevated total ERK expression, which were also reversed by L-DOPA. The data suggest the involvement of arrestins and GRKs in Parkinson disease pathology and the effects of levodopa treatment.

Animals↗