Linkage disequilibrium mapping of quantitative trait loci under truncation selection

As a dense map of single nucleotide polymorphism (SNP) markers are available, population-based linkage disequilibrium (LD) mapping or association study is becoming one of the major tools for identifying quantitative trait loci (QTL) and for fine gene mapping. However, in many cases, LD between the marker and trait locus is not very strong. Approaches that maximize the potential of detecting LD will be essential for the success of LD mapping of QTL. In this paper, we propose two strategies for increasing the probability of detecting LD: (1) phenotypic selection and (2) haplotype LD mapping. To provide the foundations for LD mapping of QTL under selection, we develop analytic tools for assessing the impact of phenotypic selection on allele and haplotype frequencies, and LD under three trait models: single trait locus, two unlinked trait loci, and two linked trait loci with or without epistasis. In addition to a traditional chi(2) test, which compares the difference in allele or haplotype frequencies in the selected sample and population sample, we present multiple regression methods for LD mapping of QTL, and investigate which methods are effective in employing phenotypic selection for QTL mapping. We also develop a statistical framework for investigating and comparing the power of the single marker and multilocus haplotype test for LD mapping of QTL. Finally, the proposed methods are applied to mapping QTL influencing variation in systolic blood pressure in an isolated Chinese population.

A 588-gene microarray analysis of the peripheral blood mononuclear cells of spondyloarthropathy patients

OBJECTIVES

To identify genes which are more highly expressed in the peripheral blood mononuclear cells (PBMC) of patients with spondyloarthropathy (SpA), rheumatoid arthritis (RA) and psoriatic arthritis (PsA), in comparison to normal subjects.

METHODS

A 588-gene microarray was used as a screening tool to select a panel of such genes from PBMC of these subjects and of normal subjects. Results were then validated by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The following genes were more highly expressed in arthritis patients than in normal subjects: macrophage differentiation marker MNDA (myeloid nuclear differentiation antigen), MRP8 and MRP14 (migratory inhibitory factor-related proteins); signalling molecules JAK3 (janus kinase 3) and MAP kinase p38 (mitogen-activated protein kinase); receptors TNFR2/p75, C-C-chemokine receptor type 1 (CCR1), C-X-C-chemokine receptor type 4 (CXCR4) and integrin beta1; and the cytokines/chemokines interleukin (IL) 1beta and IL-8. Expression of CXCR4 was unexpectedly high among all arthritis subjects. Using RT-PCR, ELISA and immunohistology, expression of stromal cell-derived factor 1 (SDF-1) was demonstrated in arthritis joints.

CONCLUSIONS

The CXCR4/SDF-1 is a potential pro-inflammatory axis for RA, PsA and SpA.

Population based linkage disequilibrium mapping of QTL: an application to simulated data in an isolated population

Despite successes in mapping and cloning genes involved in rare Mendelian diseases, genetic dissection of quantitative traits into single Mendelian factors still remains a challenging task. As the dense map of single nucleotide polymorphism (SNP) markers becomes available in the near future, linkage disequilibrium (LD) mapping will become one of major tools for mapping and identifying quantitative trait loci (QTL). In this report, we present a population-based linkage disequilibrium mapping of QTL. This method unifies the analysis of mapping QTL in humans and in model organisms and can be used for randomly sampled individuals. The proposed method is applied to search for polymorphism sites within the candidate genes 2 and 6, which influence quantitative traits Q1 and Q2 or Q5, in a simulated data set in an isolated population.

Systemic sclerosis (scleroderma): specific autoantigen genes are selectively overexpressed in scleroderma fibroblasts

The pathogenesis of systemic sclerosis (SSc) involves complex interactions between activated fibroblasts eventually leading to fibrosis, and impaired immune tolerance characterized by a variety of circulating SSc-specific autoantibodies. The expression of autoantigens in fibroblasts, a key target tissue in SSc, may play an important role in this process. To obtain a global view of this process, we examined gene expression profiles of SSc dermal fibroblasts using cDNA microarrays. The results show that dermal fibroblasts from SSc patients obtained from either affected or unaffected skin displayed a characteristic pattern of increased SSc autoantigen gene expression compared with that from normal controls. In particular, fibrillarin (p = 0.028), centromeric protein B (p = 0.01), centromeric autoantigen P27 (p = 0.042), and RNA polymerase II (220 kDa; p = 0.02) were significantly overexpressed in SSc fibroblasts. Quantitative RT-PCR confirmed overexpression of these autoantigens and also revealed increased levels of DNA topoisomerase I transcripts in SSc fibroblasts compared with normal control fibroblasts (p = 0.0318). The polymyositis/scleroderma autoantigen gene was overexpressed in some SSc patients (p = 0.09). To examine the specificity of these overexpressed autoantigen genes for SSc and its tissue specificity for fibroblasts, cDNA microarrays of dermal fibroblasts from patients with eosinophilic fasciitis and scleromyxedema were studied as well as PBMC and muscle biopsies from SSc patients. None of these tissues showed significant alterations in gene expression of SSc-specific autoantigens. Therefore, SSc-associated autoantigen genes are selectively overexpressed in SSc dermal fibroblasts, a major tissue involved in disease pathogenesis.

Biomarker identification by feature wrappers

Gene expression studies bridge the gap between DNA information and trait information by dissecting biochemical pathways into intermediate components between genotype and phenotype. These studies open new avenues for identifying complex disease genes and biomarkers for disease diagnosis and for assessing drug efficacy and toxicity. However, the majority of analytical methods applied to gene expression data are not efficient for biomarker identification and disease diagnosis. In this paper, we propose a general framework to incorporate feature (gene) selection into pattern recognition in the process to identify biomarkers. Using this framework, we develop three feature wrappers that search through the space of feature subsets using the classification error as measure of goodness for a particular feature subset being "wrapped around": linear discriminant analysis, logistic regression, and support vector machines. To effectively carry out this computationally intensive search process, we employ sequential forward search and sequential forward floating search algorithms. To evaluate the performance of feature selection for biomarker identification we have applied the proposed methods to three data sets. The preliminary results demonstrate that very high classification accuracy can be attained by identified composite classifiers with several biomarkers.

CT virtual endoscopy of the auditory ossicular chain: clinical applications

OBJECTIVE

To evaluate the clinical applications and limitations of CT virtual endoscopy (CTVE) in the auditory ossicular chain.

METHODS

CTVE of the auditory ossicular chain was performed with 1.0 mm collimation at pitch 1.0, bone algorithm, 9.6 cm field of view, and 0.1-0.2 mm reconstruction interval in 40 patients with middle ear diseases. 30 cases were confirmed by surgery. Results were compared with the findings of axial high resolution CT (HRCT) and multiplanar reformation (MPR) images and surgery.

RESULTS

The accuracy of CTVE images in detecting ossicular destruction was 92.6%, significantly higher than that of axial HRCT (83.9%) and multiplanar reformation (76.5%) images. CTVE could also clearly reveal the postoperative condition and congenital dysplasia of the auditory ossicular chain.

CONCLUSIONS

CTVE can clearly demonstrate a three-dimensional image of the auditory ossicular chain and is useful in evaluating diseases of the ear, especially the auditory ossicles. CTVE could not clearly demonstrate abnormal soft tissue within the tympanic cavity, abnormal changes of the tympanic membrane and tympanic walls, and could be easily influenced by artificial factors.

[Clinicopathologic features and prognosis of lymphoepithelioma-like carcinoma of the lung]

OBJECTIVE

To analyze the clinicopathologic features and prognosis of lymphoepithelioma-like carcinoma (LELC) of the lung.

METHODS

26 cases of pulmonary LELC with available long-term follow-up information were compared with 84 cases of pulmonary non-LELC(33 cases of squamous cell carcinoma, 36 cases of adenocarcinoma, 6 cases of adeno-squamous carcinoma and 9 cases of large cell carcinoma) with available long-term follow-up information using Kaplan-Meier method and the generalized Wilcoxon test.

RESULTS

LELC of the lung had a better prognosis than non-LELC (P < 0.05). Further study showed that pulmonary LELC had a significantly better prognosis than adeno-squamous carcinoma and large cell carcinoma. However, there was no significant prognostic differences between pulmonary LELC and squamous cell carcinoma and adenocarcinoma. Tumor recurrence and necrosis (> or = 5% of tumor) were associated with poor prognosis.

CONCLUSION

Pulmonary LELC, which is a very rare and unique entity, has a better prognosis after therapy.

[Gene chip technology and its advances in medical science]

Gene (DNA) chip or DNA microarray is a new technique developed during human genomic research programs. When DNA chip containing thousands of DNA or oligonucleotide are hybridized to labeled samples, gene expression, DNA sequencing as well as DNA mutation and polymorphism can be analyzed with high efficiency in large scale. We are able to perform this technique on dozens of specimens at once in tumor differentiation, tumor typing, tumor diagnosis, tumorigenesis, and new tumor-associated genes discovery.

[Study on the rat airway epithelial cell injury induced by bacterial infection and its pathogenesis]

OBJECTIVE

To explore the rat airway, especially small airway epithelium injury induced by Klebsiella pneumoniae infection and its pathogenesis.

METHODS

A rat airway inflammation and COPD model was induced by repeated intranasal infection with Klebsiella pneumoniae. The injury changes were dynamically observed under SEM, TEM and LM. Actin, TNF-alpha, Fos, Jun protein and their mRNA expression levels in small airway epithelium were analyzed by immunohistochemistry and in situ hybridization. The changes of lung TNF-alpha content were examined by radioimmunoassay.

RESULTS

1 week after Klebsiella pneumoniae infection the epithelial cilia cohered, fell down, partially fell off and the tight intercellular connection destroyed. 2 and 4 weeks after the infection, the injury of bronchus epithelia worsened with pronounced chronic inflammation in all bronchi. The bronchioles walls became thickened, lumen narrowed and emphysema was noted. Compared with control group, TNF-alpha mRNA expression was higher (P < 0.01) in the 2nd and 4th week while TNF-alpha protein was higher at 4 weeks (P < 0.01). From 1st week after the infection, Fos protein and mRNA expression began to elevate (P < 0.01). TNF-alpha content of lung began to increase (P < 0.01) and kept at a higher level until the 8th week.

CONCLUSIONS

Repeated intranasal injection of a certain amount of Klebsiella pneumoniae can induce airway inflammation and emphysema. The main features of early airway epithelia injury are damage of cilia and intercellular junctions, the cause of which may be associated with changes in microfilament arrangement of epithelia. High expression of TNF-alpha protein in the airway epithelia and lung parallels with epithelium injury. Fos and Jun proteins may also play important roles in up-regulating the TNF-alpha protein.

[Primary giant cell malignant fibrous histiocytoma of the lung]

A case of primary giant cell malignant fibrous histiocytoma (MFH) of the lung was reported. Gross findings showed two well demarcated isolated nodules located in the right lower lobe of the lung appeared yellowish-gray and gray-red on gross section with areas of focal calcifications, hemorrhage and necrosis. Microscopic findings showed that the tumor consisted of diffuse neoplastic histiocytes and spindle-shaped fibroblasts arranged in a prominent storiform pattern intermingled with numerous multinucleated tumor giant cells and osteoclast-like multinucleated giant cells. Focal osteoid tissue was mainly located at the periphery of the tumor. In addition, a number of scattered apoptotic multinucleated giant cells were observed. Tumor cells were positive for vimentin, alpha-1-antitrypsin, lysozyme and mac387, but negative for cytokeratin, actin, S-100, NSE, and NF. Primary giant cell MFH of the lung is a very rare malignant tumor. This tumor should be treated by prompt radical surgery.

Confirmation of susceptibility gene loci on chromosome 1 in northern China Han families with type 2 diabetes

OBJECTIVE

To confirm previous effort to identify type 2 diabetes susceptibility genes in a Northern Chinese population by conducting a new genome scan with both an increased number of type 2 diabetes families and a new set of microsatellite markers within the previously localized regions.

METHODS

A genome scan method was applied. After multiplexed PCR, electrophoreses, genescan and genotyping analysis, we obtained size information for all loci, and then a further study was done by both parametric and non-parametric linkage analysis to investigate the P values and Z values of these loci.

RESULTS

We surveyed 34 microsatellite markers which distributed within 5 regions along chromosome 1, and a total of 12,000 genotypes were screened. Evidence of linkage with diabetes was identified for 8 of the 34 loci. All P values of the 8 loci were lower than 0.05, and the highest Z value was 2.17. A very interesting finding is that all 5 markers at the p- terminal 1p36.3-1p36.23 region, spanning a long range of 16.9 cM, were identified to have a low P value of less than 0.05, which suggests that this region may contain multiple susceptibility genes. Regions 4 and 5 also confirmed the previous findings, and we narrowed these two regions to a 2.7 cM and 2.5 cM regions, respectively.

CONCLUSIONS

We further confirmed the results gained in the previous genome-wide scan using an increased number of NIDDM families and a new set of microsatellite markers lying within the initially localized regions. The fact that all 5 loci at the p- terminal region displayed a low P value of less than 0.05 suggests that more than 1 susceptibility gene may reside in this region.

Feature (gene) selection in gene expression-based tumor classification

There is increasing interest in changing the emphasis of tumor classification from morphologic to molecular. Gene expression profiles may offer more information than morphology and provide an alternative to morphology-based tumor classification systems. Gene selection involves a search for gene subsets that are able to discriminate tumor tissue from normal tissue, and may have either clear biological interpretation or some implication in the molecular mechanism of the tumorigenesis. Gene selection is a fundamental issue in gene expression-based tumor classification. In the formation of a discriminant rule, the number of genes is large relative to the number of tissue samples. Too many genes can harm the performance of the tumor classification system and increase the cost as well. In this report, we discuss criteria and illustrate techniques for reducing the number of genes and selecting an optimal (or near optimal) subset of genes from an initial set of genes for tumor classification. The practical advantages of gene selection over other methods of reducing the dimensionality (e.g., principal components), include its simplicity, future cost savings, and higher likelihood of being adopted in a clinical setting. We analyze the expression profiles of 2000 genes in 22 normal and 40 colon tumor tissues, 5776 sequences in 14 human mammary epithelial cells and 13 breast tumors, and 6817 genes in 47 acute lymphoblastic leukemia and 25 acute myeloid leukemia samples. Through these three examples, we show that using 2 or 3 genes can achieve more than 90% accuracy of classification. This result implies that after initial investigation of tumor classification using microarrays, a small number of selected genes may be used as biomarkers for tumor classification, or may have some relevance in tumor development and serve as a potential drug target. In this report we also show that stepwise Fisher's linear discriminant function is a practicable method for gene expression-based tumor classification.

A polymorphism in the promoter region of catalase is associated with blood pressure levels

Catalase is an important antioxidant enzyme that detoxifies H2O2 into oxygen and water and thus limits the deleterious effects of reactive oxygen species (ROS). Because chronic exposure to excess ROS may contribute to vascular damage, we investigated whether genetic variation in catalase was associated with susceptibility to essential hypertension (EHYT) in 324 individuals (at least 50 years old) who were randomly sampled from an isolated population living in Xiangchang, China. They were screened for genetic variation in the promoter of catalase by direct sequencing. In total, four single nucleotide polymorphisms (SNPs) were identified. The association between the SNPs and EHYT was investigated by a linear regression model under phenotypic selection; in our analyses, we used both SBP>150 mmHg and SBP>160 mmHg as thresholds. A SNP 844 bp upstream of the start codon (SNP-844) demonstrated strong evidence of association with EHYT (SBP>150 mmHg: F=5.09, P=0.008; SBP>160 mmHg: F=7.13, P=0.002). This is the first study to implicate genetic variation in catalase in susceptibility to EHYT and suggests that polymorphisms in promoter regions may be particularly relevant to the study of complex diseases.

Recursive partitioning for tumor classification with gene expression microarray data

Precise classification of tumors is critically important for cancer diagnosis and treatment. It is also a scientifically challenging task. Recently, efforts have been made to use gene expression profiles to improve the precision of classification, with limited success. Using a published data set for purposes of comparison, we introduce a methodology based on classification trees and demonstrate that it is significantly more accurate for discriminating among distinct colon cancer tissues than other statistical approaches used heretofore. In addition, competing classification trees are displayed, which suggest that different genes may coregulate colon cancers.

Skin reflectance in the Han Chinese and Tibetan populations

Genetic and environmental factors are involved in the determination of skin pigmentation in humans. With the recent development of statistical and genetic tools in mapping complex traits in humans, it is becoming feasible to utilize such methods in identifying genes involved in skin pigmentation. Furthermore, the use of new portable reflectance spectroscopy instruments such as the Photovolt ColorWalk colorimeter allows researchers to measure skin reflectance of a large number of subjects with ease and accuracy. We used a new portable instrument (Photovolt ColorWalk) to study the skin reflectance of 372 Han Chinese and 274 Tibetan individuals to establish background reflectance measurements of unexposed skin of the inner upper arm in these two populations. In addition, we explored the effect of various factors such as age and gender on skin reflectance.

Lymphoepithelioma-like carcinoma of the lung with a better prognosis. A clinicopathologic study of 32 cases

The purpose of our study was to clarify the prognosis of lymphoepithelioma-like carcinoma (LELC) of the lung, which is rare. We analyzed the clinicopathologic features of 32 cases of pulmonary LELC and compared the cases with 84 cases of pulmonary non-LELC with available long-term follow-up information. The results show that LELC of the lung as a distinct entity has a better prognosis than non-LELC. We found a significant difference in the survival rates between patients with LELC and patients with non-LELC in stage II and stages III and IV, respectively. Tumor recurrence and necrosis (5% or more of tumor) are associated with a poor prognosis. It seems that the histologic typing (Regaud type and Schmincke type) of pulmonary LELC is of no clinical value.

The effect that genotyping errors have on the robustness of common linkage-disequilibrium measures

The rapid development of a dense single-nucleotide-polymorphism marker map has stimulated numerous studies attempting to characterize the magnitude and distribution of background linkage disequilibrium (LD) within and between human populations. Although genotyping errors are an inherent problem in all LD studies, there have been few systematic investigations documenting their consequences on estimates of background LD. Therefore, we derived simple deterministic formulas to investigate the effect that genotyping errors have on four commonly used LD measures-D', r, Q, and d-in studies of background LD. We have found that genotyping error rates as small as 3% can have serious affects on these LD measures, depending on the allele frequencies and the assumed error model. Furthermore, we compared the robustness of D', r, Q, and d, in the presence of genotyping errors. In general, Q and d are more robust than D' and r, although exceptions do exist. Finally, through stochastic simulations, we illustrate how genotyping errors can lead to erroneous inferences when measures of LD between two samples are compared.

Interaction between the melanocortin-1 receptor and P genes contributes to inter-individual variation in skin pigmentation phenotypes in a Tibetan population

The melanocortin-1 receptor (MC1R) and P gene product are two important components of the human pigmentary system that have been shown to be associated with red hair/fair skin and cause type II oculocutaneous albinism, respectively. However, their contribution to inter-individual variation at the population level is not well defined. To this end, we genotyped 3 single nucleotide polymorphisms (SNPs) in the MC1R gene (Arg67Gln, Gln163Arg, Val92Met) and 2 SNPs in the P gene (IVS 13-15 and Gly780Gly) in 184 randomly ascertained Tibetan subjects, whose skin color was measured as a quantitative trait by reflective spectroscopy. Single locus analyses failed to demonstrate an association between any of the 5 SNPs and skin pigmentation. However, when an epistatic model was applied to the data, a significant gene-gene interaction was identified between Val92Met in MCIR and IVS13-15 in the P gene (F=2.43; P=0.0105). We also discuss the possible mechanisms of how gene interactions arise in signal transduction pathways.

[The clinical usefulness of helical CT multiplanar reformation, three-dimensional reconstruction and virtual laryngoscopy in laryngeal and hypopharyngeal carcinomas]

OBJECTIVE

To evaluate the clinical applications of helical CT multiplanar reformation (MPR), three-dimensional reconstruction (3D) and virtual laryngoscopy (CTVL) in laryngeal and hypopharyngeal carcinoma.

METHODS

Axial helical CT scan was performed in 24 patients with laryngeal or hypopharyngeal carcinoma, meanwhile MPR, 3D and CTVL were performed on each patient. The results were compared with the fiberoptic laryngoscopic and surgical findings.

RESULTS

Axial helical CT combined with MPR images, the accuracy of preoperative tumor staging and detection of metastatic lymph nodes were both 96%. In 25% of the cases, MPR was more informative than axial images about the extent of tumor invasion. The 3D image three-dimensionally displayed the extent of tumor invasion, and its relation to blood vessels and airway. On CTVL, the location, size and extent of intraluminal tumors of the larynx and hypopharynx when observed from above corresponded well with those observed under laryngoscope. In 4 patients, CTVL observed from below, demonstrated the relationship between the tumor and vocal cords and anterior commissure inaccessible to fiberoptic laryngoscopy.

CONCLUSION

Helical CT axial scanning combined with MPR, 3D and CTVL images, can provide more comprehensive information about laryngeal and hypopharyngeal carcinoma.

[Expression of endogenic bone morphogenetic protein in repairing rabbit skull with tissue engineering technique]

OBJECTIVE

To explore the distribution and effect of endogenic bone morphogenetic protein (BMP) in repairing rabbit skull with tissue engineered bone.

METHODS

The autologous osteoblast-like cells were instantly implanted onto polyglycolic acid (PGA) matrix coated with collagen. The rabbit skull defect models were established by resection of bilateral 1.5 cm x 1.0 cm full-thickness parietal bone in 18 New Zealand rabbits, which were randomly divided into two groups. In one group, the composite of osteoblast- like cells and PGA matrix were grafted into the defect on one side of the skull as experimental group I, leaving the same defect area on the other side as control group without any graft implanted. In the other group, simply PGA was done in the same way as experimental group II. The tissue samples were harvested at 3, 8 and 14 days postoperatively and examined by histological and immunohistochemistry methods. The concentrations of BMP in different regions of the samples were measured using computer image analysis system.

RESULTS

After 3 days of operation, the BMP positive cells were found in the matrix of experimental group I. At 8 days postoperatively, the formation of new bone on experimental group I was prior to that of experimental group II and control group. On the 14th day, bone trabecula was formed on the experimental group I, but there was only fibrous tissue on control group. The concentration of BMP on the experimental group I and II were higher than that of corresponding region on control side.

CONCLUSION

The osteoblast-like cells instantly implanted onto PGA matrix can synthesize and secrete BMP. It may be one of the reasons of tissue engineered bone inducing new bone regeneration that localizing endogenic BMP in bone defect area, increasing the concentration of endogenic BMP and improving its distribution by tissue engineering technique.

Haplotypes vs single marker linkage disequilibrium tests: what do we gain?

The genetic dissection of complex diseases represents a formidable challenge for modern human genetics. Recently, it has been suggested that linkage disequilibrium (LD) based methods will be a powerful approach for delineating complex disease genes. Most proposed LD test statistics search for association between a single marker and a putative trait locus. However, the power of a single marker association test may suffer because LD information contained in flanking markers is ignored. Intuitively, haplotypes (which can be regarded as a collection of ordered markers) may be more powerful than individual, unorganised markers. In this study, we derive the analytical tools based on standard chi-square statistics to directly investigate and compare the power between multilocus haplotypes and single marker LD tests. More specifically, novel formulas are obtained in order to calculate expected haplotype frequencies of unlimited size. This study demonstrates that the use of haplotypes can significantly improve the power and robustness of mapping disease genes. Additionally, we detail how the power of haplotype based association tests are affected by important population genetic parameters such as the genetic distance between markers and disease locus, mode of disease inheritance, age of trait causing mutation, frequency of associated marker allele, and level of initial LD. Finally, published data from the Hereditary Hemochromatosis disease region is used to illustrate the utility of haplotypes.

Gene expression profile changes in initiation and progression of squamous cell carcinoma of esophagus

Tumorigenesis is a complex process involving multiple genes. As a step toward understanding the complicated changes between normal and malignant cells, this report focused on gene expression profile variations among normal and abnormal esophageal epithelium tissues. The cDNA microarray approach was used to investigate gene expression profiles of 5 different stages during initiation and progression of esophageal cancer. According to pathological characteristics, these 5 stages were normal, dysplasia I (mild dysplasia), dysplasia II (moderate dysplasia), carcinoma in situ (CIS) and squamous cell carcinoma of esophagus (SCC). Comparing and analyzing those gene expression profiles, we observed that the expression levels of many genes changed in dysplasia I and some known tumor-related genes were over-expressed or under-expressed in all 4 abnormal stages. Using principle component analysis we identified a set of genes that may play an important role in tumor development. Hybridization data were confirmed by semi-quantitative reverse transcription-polymerase chain reaction and immunohistochemistry. These results suggest that cDNA microarray technology is a useful tool to discover genes frequently involved in esophageal neoplasia and provides novel clues to diagnosis, early detection and intervention of SCC.

[Reconstruction of tissue engineered vascular model in vitro]

OBJECTIVE

To explore the feasibility of reconstructing tissue engineered vessel in vitro.

METHODS

Bovine endothelial cells were isolated from calf thoracic aorta by enzyme digestion methods and subcultured and purified. The endothelial cells of the 3rd to 7th passages were seeded into the inner surface of tubular scaffold material by polyglycolic acid(PGA) coated with cross-linked collagen, and cultured in vitro for 10 days using dynamic rotation culture technique. Scanning electron microscopy was used to analyse the morphological characteristics, and prostacyclin released by endothelial cells was measured by radioimmunoassay of 6-keto-prostaglandin F1 alpha.

RESULTS

The VIII factor staining of cultured endothelial cells was positive. The endothelial cells adhered well on the inner surface of tubular scaffold material with confluent monolayer covering(91.2 +/- 1.5)%. The endothelialized model released prostacyclin at a rate of (4.6 +/- 0.5) micrograms/cm2.min. There was significant difference to control group (P < 0.05).

CONCLUSION

The PGA coating with collagen is an ideal scaffold for endothelial cells, the coverage rate is increased through dynamic rotation culture technique. It will lay a good foundation for architecture of a laminated structure of tissue engineered vessel.

[CT virtual bronchoscopy in the diagnosis of central lung cancer]

OBJECTIVE

To evaluate the clinical application of CT virtual bronchoscopy(VB) in the diagnosis of centrally located lung cancer.

METHODS

Forty-five cases confirmed by fiberoptic bronchoscopy and pathology underwent volume scanning using spiral CT (HiSpeed Advantage CT/i. GE Medical Systems, U.S.A). The patients examined included 33 with central lung cancer, 8 with post-operative residual bronchial stumps, 2 with post-radiotherapy lung cancer, and 2 with tracheal carcinoma. Data were transferred to computer workstation (GE Advantage Windows 3.1) and CT virtual bronchoscopic (CTVB) images with pseudocolor encoding were generated using Navigator Smooth soft-ware.

RESULTS

CTVB could reveal 100% segmental bronchus and 80% subsegmental bronchus simulating fiberoptic bronchoscopy. The tumors appeared as masses or nodules, causing bronchial wall thickening and occlusions. Post-operative residual bronchial stumps showed smooth end without recurrence of tumors or appeared as nodular protrusion if tumor recurred. The post-radiotherapy bronchial wall was uneven and there was narrowing of bronchial lumen.

CONCLUSION

CTVB is a noninvasive method of observing the airway. It stimulates the images observed under fiberoptic bronchoscopy and com be used partly in lieu of it. Associated with multiplanar reformat, CTVB can demonstrate extraluminal invasion of the tumor. The limitations of CTVB are that it is not possible to observe mucosal abnormalities and perform biopsy.

[E-cadherin associated protein expression and its significance in invasive lobular carcinoma and invasive ductal carcinoma of breast]

OBJECTIVE

To study E-cadherin associated proteins alpha-, beta-, gamma-catenin expression and their significance in invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) of breast.

METHODS

Immunohistochemistry staining (labeled streptavidin-biotin method) was used to detect alpha-, beta-, gamma-catenin expression in invasive breast carcinoma (19 cases of ILC and 32 cases of IDC ).

RESULTS

The loss and reduction rate of alpha-, beta-, gamma-catenin expression in ILC was 78.9% (15 cases), 52.6% (10 cases) and 84.2% (16 cases), respectively. The rate of alpha-, beta-, gamma-catenin expression showing loss and reduction in IDC was 75.0% (24 cases), 43.8% (14 cases) and 81.3% (26 cases), respectively. The staining intensity of alpha-, beta-, gamma-catenin expression in invasive carcinoma of breast was weaker than that in foci of carcinoma in situ (semiquantitative grading). There was a positive relationship between the expression of alpha-catenin and beta-catenin in invasive breast carcinoma. No significant association was seen between reduced protein expression of alpha-, beta-, gamma-catenin and the development of lymph node metastasis.

CONCLUSION

alpha-, beta-, gamma-catenin expression was almost identical in ILC and IDC of breast, showing significant loss and reduction of protein expression in the carcinoma cells of invasive breast carcinoma, suggesting that alpha-, beta-, gamma-catenin may lose their normal adherent ability in the pathogenesis of invasive breast carcinoma.

[Effects of DDPH on proliferation and immunophenotypes of the pulmonary vascular pericytes]

OBJECTIVE

To study the effects of 1-(2, 6-dimethylphenoxy)-2-(3, 4-dimethoxyphenylethylamino) propane hydrochloride (DDPH) on proliferation and immunophenotypes of newborn rat pulmonary vascular pericytes (PCs) induced by hypoxic endothelial cell conditioned medium (HECCM) from porcine pulmonary arteries.

METHODS

The PCs were divided into 4 groups according to the endothelial cell conditioned medium (ECCM): normoxic ECCM (NECCM) group, NECCM + DDPH group, HECCM group and HECCM + DDPH group. Cell culture, immunocytochemical staining, image analysis and flow cytometry were used to investigate the effects of HECCM and DDPH on the expression of alpha-smooth muscle actin (alpha-SM-actin) and proliferating cell nuclear antigen (PCNA) and cell cycle in PCs.

RESULTS

The alpha-SM-actin antigen in the PCs in HECCM group was more positively expressed than that in the other three groups, but CD(34) antigen and S-100 antigen were negatively expressed. The expression of alpha-SM-actin antigen, CD(34) and S-100 was positive in the groups of NECCM, NECCM + DDPH and HECCM + DDPH. The expression of alpha-SM-actin and PCNA in HECCM group was 1.32 times (F = 11.09, P = 0.000 1) and 1.24 times (F = 2.89, P = 0.025 7) that in NECCM group, 1.30 times (F = 3.65, P = 0.007 0) and 1.21 times (F = 2.63, P = 0.041 4) that in HECCM + DDPH group, respectively; The percentage of the cells in the G(0)-G(1) phase in the HECCM group was lower by 11.7% and 9.1%, in S phase higher by 5.6% and 4.2%, in G(2)-M phase higher by 6.1% and 4.9% than that in the groups of NECCM, HECCM + DDPH, respectively. The inhibitory rates of DDPH on the increased alpha-SM-actin and PCNA syntheses in PCs induced by HECCM were 23.4% and 17.1% respectively. The inhibitory rate on the increased PCs from G(0)-G(1) phase to S phase was 8.3%.

CONCLUSION

DDPH might directly inhibit PCs from proliferation and immunophenotypical transformation of smooth muscle-like cells induced by HECCM.

Gene expression profile changes in initiation and progression of squamous cell carcinoma of esophagus

Tumorigenesis is a complex process involving multiple genes. As a step toward understanding the complicated changes between normal and malignant cells, this report focused on gene expression profile variations among normal and abnormal esophageal epithelium tissues. The cDNA microarray approach was used to investigate gene expression profiles of 5 different stages during initiation and progression of esophageal cancer. According to pathological characteristics, these 5 stages were normal, dysplasia I (mild dysplasia), dysplasia II (moderate dysplasia), carcinoma in situ (CIS) and squamous cell carcinoma of esophagus (SCC). Comparing and analyzing those gene expression profiles, we observed that the expression levels of many genes changed in dysplasia I and some known tumor-related genes were over-expressed or under-expressed in all 4 abnormal stages. Using principle component analysis we identified a set of genes that may play an important role in tumor development. Hybridization data were confirmed by semi-quantitative reverse transcription-polymerase chain reaction and immunohistochemistry. These results suggest that cDNA microarray technology is a useful tool to discover genes frequently involved in esophageal neoplasia and provides novel clues to diagnosis, early detection and intervention of SCC.

[Linkage analysis of candidate genes for glucose and lipid metabolism with essential hypertension]

OBJECTIVE

To identify the genetic loci responsible for susceptibility to essential hypertension (EH) in chromosomal regions containing candidate genes involved in the regulation of glucose and lipid metabolism.

METHODS

Linkage analysis of EH were performed in 95 Chinese nuclear families with 477 subjects using the technique of fluorescence-based gene scan with microsatellite markers. Markers were selected in 11 chromosomal regions containing 18 candidate genes regulating blood glucose and lipid metabolism. The two-locus, non-parametric linkage analysis (NPL), maximum LOD score and transmission/disequilibrium test (TDT) with GENEHUNTER program were used in this study.

RESULTS

No significant linkages were found by NPL and LOD score analysis (P > 0.05 or LOD score < 1) at all loci. The results of TDT showed significant linkage with EH at D8S261 and D11S1347 (chi(2) = 11.92, P < 0.001 and chi(2) = 7.37, P < 0.01, respectively). Near these loci, there were a few candidate genes including lipoprotein lipase (LPL) and a cluster of apolipoprotein (apoA1-C3-A4).

CONCLUSION

TDT suggests significant linkage with EH at D8S261 and D11S1347. Whether the genes located at or near the two loci, such as LPL and apoA1-C3-A4, are susceptibility genes of EH need to be verified.

Relationship between tumor suppressor gene p53 and tumors of adipose tissue

OBJECTIVE

To investigate the relationship between p53 gene and tumors of adipose tissue at the level of protein and gene.

METHODS

Immunohistochemical LSAB, PCR-SSCP and DNA sequencing were used in 82 cases.

RESULTS

p53 protein is expressed only in liposarcomas, in which the positive staining rate was 48.08% (25/52). In different subtypes of liposarcomas, the positive staining rate in well differentiated liposarcomas was 30.00% (9/30), which is much lower than that of the poorly differentiated liposarcomas (P < 0.005). Abnormality in the single-stranded DNA pattern was determined in 2 samples (pleomophic liposarcomas) by PCR-SSCP analysis. Missense mutations in exon 8 codon 268 of p53 gene (AAC-->ATC) were detected by DNA sequencing. Another heterozygotic cosense mutation may exist at exon 6 codon 221 of p53 gene (GAG-->GAA).

CONCLUSIONS

The data suggest that the p53 protein has a relationship with development, differentiation and malignancy of liposarcoma. Detecting the level of p53 protein expression may be valuable in evaluating the level of differentiation and malignancy of liposarcoma. There appear point mutation on exon 8, 6 of p53 gene.

Laryngeal and hypopharyngeal carcinoma: comparison of helical CT multiplanar reformation, three-dimensional reconstruction and virtual laryngoscopy

OBJECTIVE

To evaluate the clinical application of helical CT multiplanar reformation (MPR) three-dimensional reconstruction (3D) and virtual laryngoscopy (CTVL) in laryngeal and hypopharyngeal carcinoma.

METHODS

Axial helical CT scans were performed in 22 patients with laryngeal or hypopharyngeal carcinoma, along with MPR, 3D and CTVL. These results were compared with the findings of fiber optic laryngoscopy and surgery.

RESULTS

Combining axial and MPR images, both the accuracy in preoperative tumor staging and the diagnosis of metastatic lymph nodes were 95%. MPR demonstrated more information about the extent of tumor than axial images in 23% cases; 3D image displayed clearly the extension of tumor, the vessels and airway from multiple views. The location, size and extent of tumors found in cranio-caudal CTVL corresponded well with that of laryngoscopy, and CTVL demonstrated the relationship between the tumor and vocal cords and anterior commissure by caudo-cranial approach, which was inaccessible to fiber optic laryngoscopy in 3 cases.

CONCLUSIONS

Axial images of helical CT clearly demonstrate the location, size and extent of laryngeal and hypopharyngeal carcinoma, while MPR and 3D images are useful in displaying the three-dimensional images and anatomical relation of the tumor. CTVL can clearly display the mucosal surface structures of the larynx and hypopharynx and is a good complementary method of laryngoscopy.

Computational methods for gene expression-based tumor classification

Gene expression profiles may offer more or additional information than classic morphologic- and histologic-based tumor classification systems. Because the number of tissue samples examined is usually much smaller than the number of genes examined, efficient data reduction and analysis methods are critical. In this report, we propose a principal component and discriminant analysis method of tumor classification using gene expression profile data. Expression of 2000 genes in 40 tumor and 22 normal colon tissue samples is used to examine the feasibility of gene expression-based tumor classification systems. Using this method, the percentage of correctly classified normal and tumor tissue was 87.0%. The combined approach using principal components and discriminant analysis provided superior sensitivity and specificity compared to an approach using simple differences in the expression levels of individual genes.

CT virtual bronchoscopy: imaging method and clinical application

OBJECTIVE

To evaluate the imaging method and clinical application of CT virtual bronchoscopy (CTVB).

METHODS

Fifty-two patients with bronchial and pulmonary diseases were studied with CTVB. All patients underwent fiberoptic bronchoscopy and patients with lung cancers were confirmed pathologically. Lung cancer of center type was found in 46 patients, postoperative lung cancer in 4, tracheal adenoidcystic carcinoma in 1, and bronchial diverticulum in 1. CTVB was performed using Navigator Smooth software on the workstation (Advantage Windows 3.1, GE Medical Systems). Source images included slice thickness of 3 mm or 5 mm, pitch of 1.0 or 1.5, 1.0 mm or 2.0 mm interval (overlap more than 60%) reconstruction.

RESULTS

CTVB could reveal vividly the tracheobronchial lumens, the cartilage rings, the carina and the left and right main bronchi, down to the fourth order of bronchial orifices, mimicing fiberoptic bronchoscopy. Among 46 patients with lung cancers of center type, fiberoptic bronchoscopy showed the masses in 45 patients and CTVB displayed the masses in 42. The sensitivity of CTVB was 93.3% and its accuracy was 93.5% (chi 2 = 1.33, 0.10 < P < 0.25). The tumors appeared as masses or nodules, causing bronchial stenosis (n = 35) or occlusion (n = 7). The bronchial rings near the masses were blurred, smooth or absent in contrast to the findings of fiberoptic endoscopy. Postoperative bronchial stump (n = 4) appeared to be smooth. Bronchial diverticulum exhibited a local concavity on CTVB and local protrusion on surface shadow display (SSD). CTVB could pass through the stenotic bronchi and detect the occlusive bronchi from the distal end.

CONCLUSIONS

The sensitivity of CTVB in detecting bronchial masses was higher than that of fiberoptic bronchoscopy. Combined with multiplanar reconstruction (MPR) and CTVB can demonstrate the extraluminal extension of tumors. As a noninvasive examining method, however, CTVB is limited to observe mucosal abnormalities and to obtain histologic samples.

[Experimental study on inhibitory effect of xiaochaihu decoction on duck hepatitis B virus]

OBJECTIVE

To verify the therapeutic effect of Xiaochaihu decoction (XCHD) on chronic hepatitis B, and to prove the rationality of the TCM principle "strengthening the body resistance to eliminate pathogenic factors".

METHODS

The inhibitory effects on DHBV of various doses of XCHD and its ingredients (grouped into whole recipe, partial recipe and single Bupleurum) were determined and compared, as well as compared with that of the blank control and of antiviral drug, acyclovir (ACV).

RESULTS

Inhibitory effect was shown in all the treated groups. The treatment by whole recipe of XCHD with the dose 20 times that of clinical use showed the optimal effect, the difference in comparing with other treated groups was significant, P < 0.05. The effect of whole recipe was better than that of the partial recipe or single Bupleurum, P < 0.05. Moreover, the effect was rather persistent, no rebound phenomena was observed after withdrawal of medication, while in the ACV treated group, though a better effect conld be obeained, however, the DHBV returned to the level of before treatment after cessation of ACV treatment.

CONCLUSION

The therapeutic effect of XCHD might be to supplment body resistance and remove the evil pathogen, strengthen or regular immune function, so XCHD is efficient in treating chronic hepatitis B.

Combined linkage and linkage disequilibrium mapping for genome screens

Linkage analysis and association studies, two major approaches for genetic studies of human diseases, are useful for mapping genes that are highly penetrant, but both use only part of the information that is available for mapping disease genes. Therefore, they provide limited utility when used alone. In this report, we present combined linkage and linkage disequilibrium mapping that simultaneously utilizes linkage and linkage disequilibrium information for mapping human disease genes. Compared with the existing linkage analysis and association study methods, this method has several advantages: 1) it has high statistical power by a joint analysis of linkage and linkage disequilibrium for localizing disease susceptibility loci: 2) it unifies the theory of linkage analysis and linkage disequilibrium mapping, 3) it retains the general framework for linkage analysis and, hence, can be easily incorporated into the existing software for the linkage analysis. The proposed LLDM is applied to familial hemophagocytic lymphohistiocytosis (FHL) disease.

The haplotype linkage disequilibrium test for genome-wide screens: its power and study design

The focus of human genetics continues to shift toward the dissection of complex phenotypes. Integral to these endeavors is the development of powerful analytical tools. To this end, we propose a novel method designated the haplotype linkage disequibrium (LD) test for identifying diseases genes. The basic structure of the haplotype test statistic is a chi-square in which haplotypes, as opposed to individual marker data, are compared between cases and controls. Specifically, we performed power calculations and demonstrate that the use of haplotypes improves the power of mapping disease genes. We show that this approach can be used for initial genome-wide screens in mapping disease genes. Furthermore, we investigated the factors influencing statistical power of the method and discussed basic principals underlying study design. Published data from the Hereditary Hemochromatosis region was used to illustrate the utility of the haplotype test. Also discussed is its relationship with linkage disequibrium.

Association of Epstein-Barr virus with lymphoepithelioma-like carcinoma of the lung in southern China

Having reviewed the data on 3,663 consecutive cases of primary lung carcinoma in southern China, we found that 32 cases could meet the criteria for lymphoepithelioma-like carcinoma (LELC) of the lung. To study the relationship between pulmonary LELC and Epstein-Barr virus (EBV) infection, we used in situ hybridization and immunohistochemistry techniques to detect the EBV-encoded small nonpolyadenylated RNA (EBER), latent membrane protein 1 (LMP1), and viral capsid antigen (VCA) in 32 cases of LELC and 19 cases of non-LELC lung carcinoma. Of the 32 cases, 30 (94%) showed EBER positivity. Of the 30 EBER-positive pulmonary LELC cases, 16 and 7 expressed LMP1 and VCA, respectively. In contrast with LELC, none of the 19 cases of non-LELC lung carcinoma showed EBER-, LMP1-, or VCA-positive signals in carcinoma cells. The results demonstrate that there is a close relationship between EBV infection and pulmonary LELC. EBV infection may have an essential role in the tumorigenesis of pulmonary LELC. EBV latent infection is the main status in pulmonary LELC except for individual EBV entering into a lytic cycle.

[Contrast observation on preventive effect of different traditional Chinese medicine treatments on coronary artery ligation induced myocardial ischemia in rats with diabetes mellitus]

OBJECTIVE

To compare the preventive effect of different TCM treatment on coronary artery ligation induced myocardial ischemia in rats with diabetes mellitus.

METHODS

Model rats of diabetes mellitus induced by streptozotocin were used to form myocardial ischemia models by coronary artery ligation, which were treated by modified Taohe Chengqi Decoction (TCD) and different combination of its ingredients. The effect of different TCM treatment on ischemic area, arrhythmia rate and T-wave in electrocardiogram, and 2 hrs postoperational survival rate were observed.

RESULTS

Effect of reducing ischemic area and raising survival rate (P < 0.05, P < 0.01) showed in all the groups treated by different TCM treatment, especially in the group treated with comprehensive TCM. Obvious improvement on T-wave revealed in the groups treated with TCD and comprehensive TCM (P < 0.05, P < 0.01).

CONCLUSION

Invigorating Qi and Nourishing Yin, Expelling Heat by purgation and accentuating on activating blood circulation is an effective method of TCM in treating and preventing diabetic coronary heart disease.

The effect of hypoxia on expression of basic fibroblast growth factor in pulmonary vascular pericytes

To examine whether hypoxia exerts effect on the expression of basic fibroblast growth factor (bFGF) in pulmonary vascular pericytes (PC), cell culture, in situ hybridization with probe of digoxigenin-11-dUTP-labled cDNA, immunocytochemistry and image analysis were employed in this study. The results showed that the expression amount of bFGF mRNA and protein in PC of hypoxia (H) group was 1.31 times (P < 0.01) and 1.17 times (P < 0.01) that of normoxia (N) group respectively. It suggests that hypoxia can directly enhance the expression of bFGF mRNA and protein in PC. Increased expression of bFGF may play an important role in the process of PC proliferation and differentiation of PC into smooth muscle-like cells.

Effect of c-myc antisense oligodeoxynucleotides on hypoxia-induced proliferation of pulmonary vascular pericytes

To study the effect of c-myc antisense oligodeoxynucleotides (ODNs) on proliferation of pulmonary vascular pericytes (PC) induced by hypoxia, cell culture, dot hybridization using probe of digoxigenin-11-dUTP-labeled cDNA, 3H-thymidine incorporation, immunocytochemical technique and image analysis methods were used to observe the effect of c-myc antisense ODNs on expression of c-myc gene and proliferating cell nuclear antigen (PCNA), and 3H-thymidine incorporation of PC induced by hypoxia. The results showed that hypoxia could significantly enhance the expression of c-myc and PCNA (P < 0.01), and elevate 3H-thymidine incorporation of PC (P < 0.01), but antisense ODNs could significantly inhibit the expression of c-myc and PCNA (P < 0.05), and 3H-thymidine incorporation of PC (P < 0.01). It was suggested that hypoxia could promote the proliferation of PC by up-regulating the expression of c-myc gene, but c-myc antisense ODNs could inhibit hypoxia-induced proliferation of PC by downregulating the expression of c-myc gene.

[Computed tomographic findings of the development of the bone around the vestibular aqueduct in Meniere's disease]

OBJECTIVE

To study the development of the bone around the vestibular aqueduct (VA) in Meniere's disease (MD) by CT.

METHOD

The experiment consisted of three groups; normal ear group, non-MD vertigo group and MD group. VA in each group was examined by CT, and the minimum distance between the posterior semicircular canal and the posterior petrous surface where contain the endolymphatic sac.

RESULT

VA visualization rate in MD was low, P-P distance in MD group was shorter than that of normal ear group and non-MD vertigo group.

CONCLUSION

It is the fundamental pathological anatomy in MD that VA and the bone around VA are maldeveloped.

[The study on COPD rat model produced by bacterial infection]

OBJECTIVE

To observe the role of bacterial infection in pathogenesis of COPD.

METHODS

The COPD animal model was developed by intranasal repeated injecting Klebsiella pneumoniae(K) or pneumococcal pneumoniae(P) into rat respiratory tract. Histomorphyological changes were observed, PaO2, PaCO2 and right ventricular systolic pressure (RVSP) were analysed.

RESULTS

1 week after injecting K and 4 week after injecting P, the epithelia of bronchioles showed obvious injury. From the 4th week there was severe chronic inflammatory process of bronchioles in 2 experimental groups including thickened wall, narrowed lumen and developed emphysema. In addition, the walls of arterioles accompanying bronchioles were also thickened obviously. Right ventricular systolic pressure raised in 2 experimental groups (P < 0.01). From the 16th week, PaO2 dropped and PaCO2 raised in K group.

CONCLUSIONS

Repeated injecting intranasally of the proper amount of klebsiella pneumoniae or pneumococcal pneumoniae into rats' lungs can induce rat small airway inflammation and emphysema. Combining with PaO2, PaCO2 and RVSP analysis, we suggest the model established shows main features of COPD.

Factors limiting adenovirus-mediated gene transfer into human lung and pancreatic cancer cell lines

Adenoviral vectors are a widely used means of gene transfer. However, transgene expression after adenoviral administration varies among different carcinoma cell lines. We hypothesized that this variation is attributable, in part, to the presence of cell surface molecules involved in adenoviral infection. To test this, we first assessed adenovirus-mediated transgene expression in four human lung carcinoma cell lines and four human pancreatic carcinoma cell lines in terms of luciferase activities and found it to vary from 4.8 x 10(4) to 6.1 x 10(7) relative light units/microg of protein. Then, to determine whether the molecules involved in the entry of adenovirus into host cells were responsible for this variation, we evaluated the expression of alpha(v)beta5, alpha(v), beta3, alpha5, and beta1 integrins and that of coxsackievirus and adenovirus receptor (CAR) in these cell lines. Statistical analysis revealed that the levels of beta3 were associated with the levels of transgene expression. Blocking analysis showed that adenovirus-mediated gene transfer could be blocked by antibodies against these six molecules but not by the antibodies against alpha2 or alpha3 integrins, thus suggesting that the integrins alphavbeta5, alpha(v), beta3, alpha5, and beta1 and CAR molecules could limit adenovirus-mediated gene transfer when their levels fell below a certain threshold. Furthermore, cells expressing low levels of beta3 and resistant to conventional adenoviral vectors were susceptible to a vector containing the heparin-binding domain in its fiber, thus suggesting that redirecting vectors to receptors other than CAR may bypass the integrin pathway. These findings may have implications for improving the efficiency of adenovirus-mediated gene transfer and developing novel adenoviral vectors.

[Evaluation of DNA recombinant chitinase fusion protein antigens in serological diagnosis for filariasis]

OBJECTIVE

To evaluate DNA-recombinant chitinase fusion protein antigen in serodiagnosis for Bancroft's filariasis in jirds rats with microfilaremia and normal jirds rats with ELISA, and its prospect in the market to be spread.

METHODS

Oligonucleotide was synthesized with filaria monoclonal antibody (Mf(1))-recognized microfilaria chitinase fusion protein and basic primer recognized by original clonal nucleosides, and amplified with polymerase chain reaction (PCR). PCR products were expressed in Pmal-c vector and purified by affinity chromatography. Experimental animals were inoculated with chitinase fusion protein antigen and infected with larval stage filaria Brugia malayi, respectively. Functional protein molecule of chitinase antigen was analyzed with SDS-PAGE and western blot. Serum level of specific antibody to chitinase antigen was determined by ELISA, and compared with that to microfilaria xt antigen (Mf-xt).

RESULTS

Specific function protein molecule of the above-mentioned chitinase antigen has been identified as 69,000. Serum antibody against chitinase antigen was 100% positive for jirds and patients with microfilaremia, but, that against Mf-xt only 80% positive. Serum antibody against chitinase antigen was negative for all normal jirds and normal persons, but that against Mf-xt had 5% false positive in normal serum. For those with microfilaremia from non-filariasis-prevalent areas, false sero-positivity was 5% and 20% with chitinase antigen and Mf-xt, respectively.

CONCLUSION

ELISA with DNA recombinant fusion protein antigen is a sensitive and specific method in serological diagnosis and surveillance for filariasis, with simple, easy and convenient manipulation. It can be used in field serologic surveillance and diagnosis for filariasis during the late phase in control of filariasis and can be spread in good prospects.

Evaluation of recombinant chitinase antigen in serological diagnosis and surveillance of lymphatic filariasis

Apply recombinant chitinase fusion protein antigen, enzyme-linked immunosorbent assays examined anti-filarial antibodies and evaluated of useful value in serological diagnosis and surveillance of lymphatic filariasis. The test jirds were immunized and infected by chitinase and B. malayi third stage larvae respectively. Functional protein molecular of chitinase was analyzed by SDS-PAGE, Western blot. The result shown that jirds from microfilaremia (mf) and donors with Mf were directly to react with chitinase antigen that positive rate was 100%, but Mf-xt antigen was only 80%. Normal jirds and persons sera from unepidemic control donors all were negative. False positives of 5% and 20% reacted with chitinase and Mf-xt antigens respectively. The results indicate that recombinant chitinase antigen is suitable for detection of active occult or patent lymphatic filariasis with daytime blood samples in residents of endemic areas, is easy to be performed and inexpensive.

[The effects of hypoxia on vascular pericytes of the lung]

OBJECTIVE

To study the effects of hypoxia, directly or mediated by pulmonary arterial endothelial cells, on energy metabolism, cell cycle, platelet derived growth factor (PDGF) and PDGF receptor mRNA expression of vascular pericytes of the lung in vitro.

METHODS

Use of MTT colorimetric assay, flow cytometry, nucleic acid in situ hybridization and automatic image analysis for quantitative analysis.

RESULTS

Hypoxia promoted vascular pericyte proliferation directly or through the mediation of endothelial cells to promote vascular pericyte proliferation from static phase (G(0), G(1) phase) to DNA synthesis phase (S phase) and mitotic phase (G(2) + M phase) and upregulate gene expression of PDGF and PDGF-R by vascular pericyte of the lung.

CONCLUSIONS

The low oxygen tension of alveolar gas and hypoxemia may promote transcription of PDGF and its receptor gene. Paracrine and autocrine PDGF may induce proliferation of vascular pericytes of the pulmonary vessels and may play a role in pulmonary hypertension and structural remodeling of the pulmonary vessels, especially in the neomuscularization of nonmuscular pulmonary arterioles.

[Detection of Epstein-Barr virus, cell proliferation and apoptosis in thymic tumors]

OBJECTIVE

To investigate the incidence of thymic tumors in Guangzhou, its association with EBV infection and the cell proliferation and apoptosis characteristics of these tumors.

METHODS

EBV encoded small RNAs (EBERs) were detected in 43 thymic tumors and 7 thymic hyperplasia samples by use of in situ hybridization, EBNA-1, LMP-1, PCNA, bcl-2 and p53 were examined using immunohistochemical methods, cell apoptosis was evaluated by TUNEL (TdT-mediated dUTP-X nick end labelling) in situ cell death detection kit.

RESULTS

1. Thymic diseases only accounted for 0.057% of biopsies in the Guangzhou area. Thymic tumor and hyperplasia accounted for 74.7% and 18.6% in thymic diseases respectively. Thymic lymphoepithelimoa-like carcinoma (LELC) occurred in 2.7% of thymic tumors. 2. EBV encoded products (EBERs, EBNA-1 and LMP-1) were not detected in 50 thymic disease specimens. 3. Marked proliferation (3+-4+) grade thymomas (0/18 cases) was much lower than that of thymic carcinomas (10/20 cases), and the marked apoptotic (2+-4+) grade was higher in thymomas (15/18) than the thymic carcinomas (13/20). 4. The p53 protein accumulation rate in thymic carcinomas (8/20) was significantly higher than that of thymomas (1/18). The apoptotic grade is significantly related to p53 accumulation in thymic epithelial tumors. 5. The bcl-2 over expression could be detected both in thymomas and thymic carcinomas.

CONCLUSIONS

1. Thymic diseases, including thymic LELC, is very rare in Guangzhou and is not closely associated with EBV infection. 2. Thymic carcinomas have a relatively rapid growth rate compared to thymomas. 3. p53 gene mutation may play an important role in the carcinogenesis of thymic carcinoma, and bcl-2 over-expression may also be involved in the evolution of thymic epithelial tumors. 4. Wild type p53 protein may exert an apoptosis-inducing function in thymic epithelial tumors, including thymomas and carcinomas, and a proliferation inhibiting function only in thymomas.

[Effect of hypoxia on proliferation and differentiation of the pulmonary vascular pericytes]

OBJECTIVE

To study the effect of hypoxia on proliferation and differentiation of the pulmonary vascular pericytes (PC).

METHODS

Cell culture, (3)H-thymidine incorporation ((3)H-TdR), immunocytochemistry and image analysis methods were used.

RESULTS

It was found that the (3)H-thymidine incorporation, the expression amounts of proliferating cell nuclear antigen (PCNA) and alpha-smooth muscle actin (alpha-SM-Actin) in direct hypoxia (H) group was 2.16 times (P < 0.01), 1.16 times(P < 0.01) and 1.11 times (P < 0.05) that of normoxia (N) group, in hypoxic endothelial cell conditioned medium (HECCM) group was 1.8 times (P < 0.01), 1.15 times (P < 0.01) and 1.12 times (P < 0.05) that of normoxic endothelial cell conditioned medium (NECCM) group.

CONCLUSIONS

It was suggested that hypoxia can stimulate pulmonary artery endothelial cells (PAEC) to secrete some growth factors to enhance PC proliferation and transformation of smooth muscle-like cells.

Comparison of the power and accuracy of biallelic and microsatellite markers in population-based gene-mapping methods

Because of their great abundance and amenability to fully automated genotyping, single-nucleotide polymorphisms (SNPs) and simple insertion/deletion are emerging as a new generation of markers for positional cloning. Although the efficiency and cost associated with the markers are important in the mapping of human disease genes, the power to detect the linkage between the marker and the disease locus, as well as the accuracy of the estimation of the map location of the disease gene, dictate the selection of the markers. Both the power and the accuracy depend not only on the type of the markers but also on other factors, such as the age of the disease mutation, the magnitude of the genetic effect, the marker-allele distribution in the population, mutation rates of marker loci, the frequency of the disease allele, the recombination fraction, and the methods for mapping the human disease genes. In this article, we develop a mathematical framework and the analytical formulas for calculation of the power and the accuracy and investigate the impact that the aforementioned factors have on the power and the accuracy, by using two population-based gene-mapping methods-likelihood-based linkage-disequilibrium mapping and the transmission/disequilibrium test, for both biallelic SNPs and microsatellites. These studies provide not only guidance in selection of the markers and in the design of the sample scheme for positional cloning but also insight into the biological bases of the mapping of human disease genes.

The power of linkage detection by the transmission/disequilibrium tests

Despite growing interest in the use of transmission/disequilibrium test (TDT)-type analysis in association studies, there has been surprisingly scant attention paid to the issues as to what factors affect the power of the TDT for linkage detection. We demonstrate in this paper that the power is a function of several genetic parameters including the recombination fraction, penetrance, the age of mutant disease allele, marker allele frequency, recurrent mutation rates at marker and/or disease locus, and initial linkage disequilibrium. In general, TDT has greater power to detect linkage for a 'recessive'-type model than for a 'dominant'-type model. Its power also is higher when there is greater differential in marker allele frequency between disease and normal chromosomes. And since the presence of marker mutation and/or recurrent mutation at the disease locus, or the age of disease mutation, or the initial incomplete linkage disequilibrium, all hasten the process to reach linkage equilibrium, all of them can affect the power of TDT to detect linkage. The effect of marker mutation rate or the mutation rate at the disease locus can be minimal if mutation rates are low. The results on the impact of recombination fraction and of age of mutation on the power of TDT in linkage detection seem to be disheartening for gene mappers of complex diseases: for a disease with small genetic influence, a vastly large sample size is needed to detect the linkage, if the marker is not very close to the disease locus. This is particularly true if the disease is 'old'.