Biomedical subjects

Lihua Li

Publications and source records attributed to Lihua Li.

15 recordsLinked to original sources

PubMed2026

Association of long-term exposure to ambient air pollution and myopia in Chinese children.

Ambient air pollution is recognized as a major global health concern, but evidence on its association with childhood myopia remains limited, particularly under multi-pollutant exposure conditions. A school-based study was conducted in Tianjin, China, including 212,566 students in grades 4-6. The 3-yr mean concentrations of particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5), its major components (sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), organic matter (OM), and black carbon (BC)), and ozone (O3) were estimated using machine-learning exposure models and linked to school locations. Restricted cubic splines and quartile-based modified Poisson models were used to assess single-pollutant exposure-response relationships, and quantile-based g-computation was applied to estimate joint pollutant associations. In single-pollutant models, the highest quartile of SO42- was associated with higher myopia prevalence compared with the lowest quartile (PR = 1.10; 95% CI, 1.07-1.13). O3 showed weaker and non-monotonic positive patterns (Q4 vs Q1: PR = 1.03; 95% CI, 1.00-1.05). In mixture analyses, a one-quartile increase in joint exposure was associated with higher myopia prevalence (PR = 1.017; 95% CI, 1.007-1.027). Sensitivity analyses generally supported the direction of the main findings. These findings suggest that long-term exposure to specific ambient air pollutants may be associated with myopia in school-aged children.

Chemical components↗

PubMed2006

Computerized analysis of tissue density effect on missed cancer detection in digital mammography.

This paper presents a study of the analysis of breast density in missed cancer cases and the effect of tissue density on cancer detection. A total of 100 missed cancer cases were collected. The breast density tissue was segmented with a statistical-based method. A set of tests was then applied to examine: (1) the differences in density between the mammograms at the detected stage and that at missed stage; (2) the density difference between the cancerous mammograms and their contra-lateral normal mammograms in the missed cancer cases; (3) the effect of breast density on CAD cancer detection. The results demonstrate that breast density is an important factor affecting not only radiologist's reading but also CAD performance. In order to improve early detection of breast cancer, a special effort should be directed to the high dense breast cases in CAD system design.

Breast Neoplasms↗

PubMed2006

Expression of tumor necrosis factor alpha and neuronal apoptosis in the developing rat brain after neonatal stroke.

Increased expression of tumor necrosis factor alpha (TNFalpha) has been shown in adult stroke models. However, its expression and relationship with neuronal apoptosis in neonatal rats with transient middle cerebral artery occlusion (MCAO) have not been clearly elucidated. We studied the expression and distribution of TNFalpha and neuronal apoptosis in a postnatal Day 10 rat MCAO model using reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot, immunohistochemistry, fluorescence double-labeling, and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) analyses. We found TNFalpha mRNA expression increased at 2h and was maintained at high levels until 24h after reperfusion. TNFalpha protein expression was significantly increased from 4 to 8h (p < 0.01) lasting through 24h (p < 0.05) after reperfusion compared to the sham controls. TNFalpha immunoreactive cells were colocalized to neurons in both the core and the penumbra areas of the ischemic cortex. However, apoptotic cells were mainly distributed in the penumbra area and colocalized to neurons as well as to TNFalpha immunoreactive cells in the ischemic cortex. Our findings suggest that TNFalpha expression increases after neonatal stroke and is associated with neuronal apoptosis after transient focal cerebral ischemia.

Animals↗

PubMed2006

Nok plays an essential role in maintaining the integrity of the outer nuclear layer in the zebrafish retina.

Proper visual function of the vertebrate retina requires the maintenance of the integrity of the retinal outer nuclear layer (ONL), which is often affected in many blinding human retinal diseases. While the structural integrity of the ONL has long been considered to be maintained primarily through the outer limiting membrane (OLM), we have little knowledge on the development and maintenance of the OLM itself. Here, by analyzing the adhering properties of photoreceptors in zebrafish N-cad and nok mutants, we demonstrated for the first time that the nok gene is essential for the establishment and/or maintenance of the OLM. In addition, our results imply the possibility that Nok, Crumbs, and their associated proteins may constitute a type of photoreceptor-photoreceptor junctional complex that has not be described before. Thus, our study provides novel insights into the mechanisms by which the integrity of the ONL is maintained in the vertebrate retina.

Animals↗

PubMed2006

[Preparation and biocompatibility of a novel cornea scaffold material].

A novel cornea tissue scaffold material was prepared with N-vinly pyrrolidome (NVP) and a biodegradable crosslinking agent by radical polymerization, using azoisobutyronitrile (AIBN) as initiator. Water absorption test and contact angle measure were conducted, and the degradation process of material was investigated. The biocompatibility evaluation was carried out by implantation of material in the rabbits, and by cell culture. The water absorption was over 104%, the contact angle was lower than 41degrees, and the degradation speed in vitro kept steady. The results of implantation in the rabbits showed that the material was almost degraded 3 months later and lots of collagen and cornea stroma cells appeared in it,but there was no inflammation around it. The result of epithelial cells culture showed that the cells conglutinated on the material, but no remarkable cytotoxicity was noted.

Animals↗

PubMed2005

Molecular and biochemical characterization of the Fe(III) chelate reductase gene family in Arabidopsis thaliana.

Iron chelate reductase is required for iron acquisition from soil and for metabolism in plants. In the genome of Arabidopsis thaliana there are eight genes classified into the iron chelate reductase gene family (AtFROs) based on sequence homology with AtFRO2 (a ferric chelate reductase in Arabidopsis). They are localized on chromosome 1 (three AtFROs) and chromosome 5 (five AtFROs) of Arabidopsis and show a high level of amino acid sequence similarity to each other. An assay for ferric chelate reductase activity revealed that AtFRO2, AtFRO3, AtFRO4, AtFRO5, AtFRO7 and AtFRO8 conferred significantly increased iron reduction activity compared with the control when expressed in yeast cells, indicating that the six AtFROs encode iron chelate reductases functioning in iron homeostasis in Arabidopsis. AtFRO2 displayed the highest iron reduction activity among the AtFROs investigated, further demonstrating that AtFRO2 is a major iron reductase gene in Arabidopsis. AtFRO2 and AtFRO3 were mainly expressed in roots of Arabidopsis, AtFRO5 and AtFRO6 in shoots and flowers, and AtFRO7 in cotyledons and trichomes, whereas the transcription of AtFRO8 was specific for leaf veins. Considering the tissue-specific expression profiles of AtFRO genes, we suggest that AtFRO2 and AtFRO3 are two Fe(III) chelate reductases mainly functioning in iron acquisition and metabolism in Arabidopsis roots, while AtFRO5, AtFRO6, AtFRO7 and AtFRO8 are required for iron homeostasis in different tissues of shoots.

Arabidopsis↗

PubMed2005

Postmortem changes in the central nervous system and adrenal medulla of the heroin addicts.

This study describes the pathological changes in 20 heroin addicts (12 male and 8 female) autopsied 24 h after sudden death. The central nervous system (including the pituitary body) and the adrenal medulla were studied, along with those from age-matched controls who died from traffic accidents. Immunohistochemistry and histological (Hematoxylin and eosin) observation were performed. Some neuronal cells in every region of the CNS were positive for opioid receptors but these cells were most numerous in the hippocampus. Positive opioid fibers were most abundant in the basal ganglia region. Histopathology indicated coagulative changes of cytoplasm and dissolution of Nissl bodies of neuron. Edema of nerve fibers was frequently demonstrated. Pituitary body showed an evident decrease or even absence of basophils in the pars anterior. The adrenal medulla featured a down regulation of chromaffin granules. Degeneration of CNS neurons and fibers, alterations in hormonal and blood pressure regulation therefore would be the prime targets of heroin addiction in human subjects.

Adrenal Medulla↗

PubMed2005

Multivalent vancomycins and related antibiotics against infectious diseases.

This review discusses the recent development of multivalent antibiotics as potential therapeutic agents against infections caused by antimicrobial drug resistant microbes. The discussion focuses on vancomycin because of its important clinical relevance and well-elucidated molecular mechanism of antimicrobial drug resistance. The first section recounts the increased occurrence of vancomycin resistance in the world; the second section briefly discusses the mechanistic study of vancomycin resistance; the third section presents the currently established design principles of multivalent vancomycins; the fourth section examines the structural-activity relationships of multivalent vancomycins; the fifth section describes relevant studies on multivalent antibiotics; and the last section summarizes advantages and limitations of multivalent antibiotics.

Anti-Bacterial Agents↗

PubMed2004

Data mining techniques for cancer detection using serum proteomic profiling.

OBJECTIVE: Pathological changes in an organ or tissue may be reflected in proteomic patterns in serum. It is possible that unique serum proteomic patterns could be used to discriminate cancer samples from non-cancer ones. Due to the complexity of proteomic profiling, a higher order analysis such as data mining is needed to uncover the differences in complex proteomic patterns. The objectives of this paper are (1) to briefly review the application of data mining techniques in proteomics for cancer detection/diagnosis; (2) to explore a novel analytic method with different feature selection methods; (3) to compare the results obtained on different datasets and that reported by Petricoin et al. in terms of detection performance and selected proteomic patterns. METHODS AND MATERIAL: Three serum SELDI MS data sets were used in this research to identify serum proteomic patterns that distinguish the serum of ovarian cancer cases from non-cancer controls. A support vector machine-based method is applied in this study, in which statistical testing and genetic algorithm-based methods are used for feature selection respectively. Leave-one-out cross validation with receiver operating characteristic (ROC) curve is used for evaluation and comparison of cancer detection performance. RESULTS AND CONCLUSIONS: The results showed that (1) data mining techniques can be successfully applied to ovarian cancer detection with a reasonably high performance; (2) the classification using features selected by the genetic algorithm consistently outperformed those selected by statistical testing in terms of accuracy and robustness; (3) the discriminatory features (proteomic patterns) can be very different from one selection method to another. In other words, the pattern selection and its classification efficiency are highly classifier dependent. Therefore, when using data mining techniques, the discrimination of cancer from normal does not depend solely upon the identity and origination of cancer-related proteins.

Biomarkers, Tumor↗

PubMed2004

Isolation and characterization of Fe(III)-chelate reductase gene LeFRO1 in tomato.

Tomato is a model plant for studying molecular mechanisms of iron uptake and metabolism in strategy I plants (dicots and non-graminaceous monocots). Reduction of ferric to ferrous iron on the root surface is an obligatory process for iron acquisition from soil in these plants. LeFRO1 encoding an Fe(III)-chelate reductase protein was isolated from the tomato genome. We show that expression of LeFRO1 in yeast increases Fe(III)-chelate reductase activity. In a transient expression analysis we found that LeFRO1 protein was targeted on the plasma membrane. LeFRO1 transcript was detected in roots, leaves, cotyledons, flowers and young fruits by RT-PCR analysis. Abundance of LeFRO1 mRNA was much lower in young fruits than in other tissues. The transcription intensity of LeFRO1 in roots is dependent on the iron status whereas it is constitutively expressed in leaves. These results indicate that LeFRO1 is required in roots and shoots as well as in reproductive organs for iron homeostasis and that its transcription in roots and shoots is regulated by different control mechanisms. The expression of LeFRO1 was disrupted in the iron-inefficient mutants chloronerva and T3238 fer, indicating that FER and CHLN genes are involved in the regulation of LeFRO1 expression in tomato roots. The differential expression of LeFRO1 and LeIRT1 (an iron-regulated metal transporter gene in tomato) in roots of T3238 fer under iron-deficient and -sufficient conditions suggests that the FER gene may regulate expression of LeFRO1 more directly than that of LeIRT1 in tomato roots.

Amino Acid Sequence↗

PubMed2003

[Preparation and biological evaluation of PLA/chitosan composite materials].

Hypersusceptibility test, pyrogen test, cell cultivation, and toxicity examination were applied in the biological evaluation of the poly(lactic acid) (PLA)/chitosan composite materials. The results indicated that all the materials were negative, conforming to the ISO10993-1. The cell could grow well on the surface of the materials. So the PLA/chitosan composite materials have good biocompatibility and can be planted in the body as scaffolds.

Animals↗

PubMed2002

Computer-aided diagnosis of masses with full-field digital mammography.

RATIONALE AND OBJECTIVES: The authors developed and evaluated a method of computer-aided diagnosis (CAD) for mass detection with full-field digital mammography (FFDM). MATERIALS AND METHODS: The new CAD method for FFDM employs adaptive, nonlinear multiscale processing and hybrid classification methods. The major strategies are (a) to "standardize" the mammographic image before it is input to the analysis modules, (b) to adapt the segmentation of suspicious regions adapt to accommodate different characteristics of masses and mammograms, and (c) to use combined "hard" and "soft" decision making in discriminating between mass and normal tissue regions. Two data sets of diagnostic FFDM mammograms were used. The training data set includes 36 normal and 24 abnormal mammograms (34 masses), and the testing data set includes 24 normal and 10 abnormal mammograms (10 masses). The tumors in this diagnostic database were more subtle and difficult to detect than those in screening databases the authors have used before. RESULTS: With the limited database and a partial optimization, a sensitivity of 91% was obtained in training, with a false-positive rate of 3.21 per image. At this trained operating point of the CAD system, six of 10 subtle masses were detected in testing. CONCLUSION: The CAD algorithms developed in screen-film mammography can be modified for FFDM. More data analysis and system optimization and evaluation will be needed before CAD can be integrated efficiently into the performance of FFDM.

Algorithms↗

PubMed2002

[Novel scaffold materials for tissue engineering].

In this paper, the resorbable and degradable biomaterials often used in recent years are reviewed. These materials include natural and synthetical ones such as collagen, protein fiber, chitosan, polylactic acid (PLA), polyglycolic acid(PGA), polyanlydrides, etc.

Biocompatible Materials↗

PubMed2002

[Treatment of capsular contracture through areolar incision after augmentation mammaplasty].

OBJECTIVE: To explore the treatment of breast sclerosis caused by capsular contracture after augmentation mammaplasty, and preventive measures after the treatment to avoid the recurrence. METHODS: With the incision through periareola, a part of the fibrous capsule and fibrillate tissue which is between the base of the capsula and the wall of the capsula were resected in the shape of wedge. At the same time, the wall of the capsular cavity was incised in radiant shape to relax it. After operation, the early and effective massage should be fully used. RESULTS: 17 case of 26 case were given follow-up over half a year, the results were satisfactory. CONCLUSIONS: After capsular contracture was relaxed and a part of the fibrous capsula between the base and the wall of the capsular cavity was resected in the shape of wedge, the prosthesis can be moved smoothly in the suitable cavity without any obstruction. In addition to the early and effective massage after operation, the methods might reach the ideal results.

Adult↗

PubMed2002

[Study on preparation and property of PLA/liquid crystal composite membranes].

In this paper we synthesised two kinds of hydrophilic liquid crystal, i.e. cholesteryl triethenyl glycol carbonate (TCC), cholesteryl tetraethenyl glycol carbonate (TeCC), which were blended with PLA with certain contents to form composite membranes. Contact angle test showed that the contact angle decreases with the increase of liquid crystal. The blood-compatibility of the composite membranes was assessed by blood clotting time and hemolysis ratio which showed that these PLA/liquid crystal composite membranes with the content of 30%-40% liquid crystal appeared to be beneficial in improving the blood compatibility and anticoagulation.

Biocompatible Materials↗