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Biomedical subjects

L Q Zhou

Publications and source records attributed to L Q Zhou.

14 recordsLinked to original sources
PubMed2006

Clustering of protein structures using hydrophobic free energy and solvent accessibility of proteins.

The hydrophobic free energy and solvent accessibility of amino acids are used to study the relationship between the primary structure and structural classification of large proteins. A measure representation and a Z curve representation of protein sequences are proposed. Fractal analysis of the measure and Z curve representations of proteins and multifractal analysis of their hydrophobic free energy and solvent accessibility sequences indicate that the protein sequences possess correlations and multifractal scaling. The parameters from the fractal and multifractal analyses on these sequences are used to construct some parameter spaces. Each protein is represented by a point in these spaces. A method is proposed to distinguish and cluster proteins from the alpha, beta, alpha + beta, and alpha/beta structural classes in these parameter spaces. Fisher's linear discriminant algorithm is used to give a quantitative assessment of our clustering on the selected proteins. Numerical results indicate that the discriminant accuracies are satisfactory. In particular, they reach 94.12% and 88.89% in separating proteins from {alpha, alpha + beta, alpha/beta} proteins in a three-dimensional space.

Annexin A6↗
PubMed2005

Phylogeny of prokaryotes and chloroplasts revealed by a simple composition approach on all protein sequences from complete genomes without sequence alignment.

The complete genomes of living organisms have provided much information on their phylogenetic relationships. Similarly, the complete genomes of chloroplasts have helped to resolve the evolution of this organelle in photosynthetic eukaryotes. In this paper we propose an alternative method of phylogenetic analysis using compositional statistics for all protein sequences from complete genomes. This new method is conceptually simpler than and computationally as fast as the one proposed by Qi et al. (2004b) and Chu et al. (2004). The same data sets used in Qi et al. (2004b) and Chu et al. (2004) are analyzed using the new method. Our distance-based phylogenic tree of the 109 prokaryotes and eukaryotes agrees with the biologists "tree of life" based on 16S rRNA comparison in a predominant majority of basic branching and most lower taxa. Our phylogenetic analysis also shows that the chloroplast genomes are separated to two major clades corresponding to chlorophytes s.l. and rhodophytes s.l. The interrelationships among the chloroplasts are largely in agreement with the current understanding on chloroplast evolution.

Chloroplasts↗
PubMed2002

Experimental and numerical studies of noise-induced coherent patterns in a subexcitable system.

A subexcitable medium of Belousov-Zhabotinsky (BZ) reaction subjected to external Gaussian white noise is studied in experiments and numerical simulations. We observe that at an optimal level of noise the wave sources of excited traveling waves become synchronous, as though there exists a long distance spatial correlation. The synchronous behavior fades if the noise level becomes larger or smaller. Numerical simulations confirm the experimental findings, and point out that the best synchronous behavior takes place when the signal-to-noise ratio of waves becomes largest.

Journal Article↗
PubMed2002

[The application of magnetic resonance imaging transfer to the study of multiple sclerosis patients: review and analysis of literature].

The purpose of this review of the literature is to analyze the contribution of magnetization transfer (MT) imaging techniques in understanding the various characteristics of multiple sclerosis. MT imaging allows contrast augmentation by use of magnetization transfer contrast. MT imaging allows lesion characterization by means of quantification of the degree of signal loss due to magnetization transfer contrast by a magnetization transfer ratio. It is used as an indicator of tissue destruction; in particular, to demyelination. Both applications of MT imaging in multiple sclerosis are studied in this review, as well as the methodological and technical limitations.

Acute Disease↗
PubMed2001

Immunogene therapy of tumors with vaccine based on Xenopus homologous vascular endothelial growth factor as a model antigen.

Overcoming immune tolerance of the growth factors associated with tumor growth should be a useful approach to cancer therapy by active immunity. We used vascular endothelial growth factor (VEGF) as a model antigen to explore the feasibility of the immunogene tumor therapy with a vaccine based on a single xenogeneic homologous gene, targeting the growth factors associated with angiogenesis. To test this concept, we constructed a plasmid DNA encoding Xenopus homologous VEGF (XVEGF-p) and control vectors. We found that immunogene tumor therapy with a vaccine based on XVEGF was effective at both protective and therapeutic antitumor immunity in several tumor models in mice. VEGF-specific autoantibodies in sera of mice immunized with XVEGF-p could be found in Western blotting analysis and ELISA assay. The purified immunoglobulins were effective at the inhibition of VEGF-mediated endothelial cell proliferation in vitro, and at antitumor activity and the inhibition of angiogenesis by adoptive transfer in vivo. The elevation of VEGF in the sera of the tumor-bearing mice could be abrogated with XVEGF-p immunization. The antitumor activity and production of VEGF-specific autoantibodies, significantly elevated IgG1 and IgG2b, could be abrogated by the depletion of CD4(+) T lymphocytes. The observations may provide a vaccine strategy for cancer therapy through the induction of autoimmunity against the growth factors associated with tumor growth in a cross reaction with single xenogeneic homologous gene and may be of importance in the further exploration of the applications of other xenogeneic homologous genes identified in human and other animal genome sequence projects in cancer therapy.

Animals↗
PubMed2000

Immunotherapy of tumors with xenogeneic endothelial cells as a vaccine.

The breaking of immune tolerance against autologous angiogenic endothelial cells should be a useful approach for cancer therapy. Here we show that immunotherapy of tumors using fixed xenogeneic whole endothelial cells as a vaccine was effective in affording protection from tumor growth, inducing regression of established tumors and prolonging survival of tumor-bearing mice. Furthermore, autoreactive immunity targeting to microvessels in solid tumors was induced and was probably responsible for the anti-tumor activity. These observations may provide a new vaccine strategy for cancer therapy through the induction of an autoimmune response against the tumor endothelium in a cross-reaction.

Amino Acid Sequence↗
PubMed1998

Primary non-Hodgkin's lymphoma of the nasal cavity: prognostic significance of paranasal extension and the role of radiotherapy and chemotherapy.

BACKGROUND: This study was conducted to determine whether the paranasal extension of a primary non-Hodgkin's lymphoma (NHL) of the nasal cavity has any deleterious effect on patient outcome. METHODS: One hundred and seventy-five patients with previously untreated nasal NHL were reviewed. There were 2 with low grade, 107 with intermediate grade, 17 with high grade, and 49 with unclassifiable lymphomas. In 48 cases the immunophenotype was available and 46 were T-cell lymphoma. According to the Ann Arbor system, there were 133 patients with Stage IE, 28 with Stage IIE, 4 with Stage IIIE, and 10 with Stage IVE lymphomas. Stage IE was subdivided into limited Stage IE (i.e., confined to the nasal cavity [67 patients]) or extensive Stage IE (i.e., presenting with extension beyond the nasal cavity [66 patients]). For patients with limited Stage IE disease the treatment of choice was radiotherapy with or without chemotherapy. In patients with extensive Stage IE disease, treatment was comprised of a combination of chemotherapy and radiotherapy or radiotherapy alone. For patients with a more advanced stage of disease (IIE-IVE), chemotherapy was an integral part of the treatment and was completed by irradiation, especially for patients with Stage IIE disease. RESULTS: The actuarial overall survival (OS) and disease free survival (DFS) rates at 5 years for the whole group were 65% and 57%, respectively. The 5-year OS and DFS rates were influenced by stage, with a gradual decrease from 75% and 68% for Stage IE disease to 35% and 28% for Stage IIE disease, and 31% and 19% for Stage IIIE/IVE disease. Patients with limited Stage IE disease survived significantly longer (90% 5-year OS) compared with those with extensive Stage IE disease (57% 5-year OS; P < 0.001). For 67 patients with limited Stage IE disease, the 5-year OS was 89% with radiotherapy alone and 92% with radiotherapy and chemotherapy, whereas for 66 patients with extensive Stage IE disease, the 5-year OS was 54% with radiotherapy and 58% with combined modality therapy or chemotherapy (P > 0.05). CONCLUSIONS: The prognosis of patients with primary NHL of the nasal cavity is stage dependent. In this large cohort of Stage IE patients, it was demonstrated that the paranasal local extension was a significant prognostic factor associated with poorer treatment outcome. The authors believe that Ann Arbor Stage IE should be subclassified further into limited and extensive Stage IE. The addition of chemotherapy did not appear to modify significantly the survival of patients with either limited or extensive Stage IE disease. The extranodal progression observed in patients with extensive Stage IE and Stage IIE-IVE disease clearly illustrates the need for improvement of systemic treatment.

Adolescent↗
PubMed1996

Effect of polysaccharide-peptide (PSP), an extract from yun-zhi, on chemotherapy-induced cytopenias.

Polysaccharide-peptide (PSP) is a protein-bound complex carbohydrate derived from mycelia extract of Chinese fungus coriolus versicolor, or better known as Yun-Zhi. It has been shown to inhibit growth of cultured tumour cells, and it prevents cytotoxic-induced bone marrow suppression. An animal study was conducted with 24 Wistar rats to verify the myeloprotective effect of PSP. The rats were divided into two equal groups: group A (given cyclophosphamide [CTX]) and group B (given PSP and CTX). The body weights were similar in both groups of rats. In phase 1, all rats were given intravenous CTX 75 mg/kg. In addition, B rats received PSP 20 mg/day orally from 7 days before CTX to 14 days after CTX. Phase 2 was carried out two weeks after full recovery from CTX-induced cytopenia. The CTX was decreased to 60 mg/kg, and the group B rats received an increased dose of PSP 1.2 g/day for the same 21 days. In both phases, the CTX was well tolerated. Nadir white blood cell count was reached on day 4 and all counts recovered by day 10. There was no difference in absolute neutrophil, lymphocyte and platelet counts between groups A and B. We concluded that oral PSP did not prevent CTX-induced cytopenia in rats.

Adjuvants, Immunologic↗
PubMed1994

Engineering the maltose binding protein for reagentless fluorescence sensing.

This paper describes a mutant of the maltose binding protein (MBP) in which the serine residue at position 337 is replaced by a cysteine residue using site-directed mutagenesis. The mutant MBP has an approximately 2-fold lower affinity for maltose, and the cysteine residue can be modified with 4-[N-(2-(iodoacetoxy)ethyl)-N-methylamino]-7-nitrobenz-2-oxa-1,3-diazole (IANBD) and 6-acryloyl-2-(dimethylamino)-naphthalene (acrylodan). This combined genetic and chemical modification places the fluorophores close to the maltose binding site such that when the ligand is added the fluorescence intensity of the labels increases by 60-180% over that of the ligand-free form. This change is consistent with the fluorophores being buried when the conformation of the protein changes with maltose binding. Titration of the labeled mutant proteins yields dissociation constants for maltose of 62 +/- 0.2 and 0.8 +/- 0.01 microM respectively for the IANBD and acrylodan modifications. The application of this strategy of combined genetic and chemical modification to the development of reagentless fluorescence sensing is discussed.

2-Naphthylamine↗
PubMed1994

[Clinical analysis of 126 cases with NHL in extra-node of head and neck patients in stage I and II].

UNLABELLED: From 1987.1.1. to 1990. 12. 31. 126 cases of extranode untreated non-Hodgkin's lymphoma (NHL) in I-II stage were analysed. All of the 126 cases had proved by pathology. The sites of primary disease were oral-pharynx in 64.3%, nasal cavity in 31% and others in 4.7%. The age of patients was between 5-69 (30-60 in 62.7%). According to the international working dassification, there was 1 case of low grade, 48 (38%) of intermediate and 77(61%) of high grade. According to Ann Arbor clinical staging, there were 33 cases of stage I and 93 cases of stage II. According to the pathological grades and clinical stages, the treatment was divided into 4 groups. (1) CT-RT 63 cases, (2) RT-CT 26 cases, (3) RT 32 cases and (4) CT 5 cases. After treatment, CR were obtained in 101 cases, PR 18 cases and P 3 cases, CR+PR were 97.5%. The 1,2,3,4,5 years survival rates of the 126 cases were 83.3% (105/126), 70.6% (89/126), 68.2% (60/88), 62.2% (46/74), 58.3% (21/36), respectively. CONCLUSION: (1) The pathological grades were not closely related to the survival rate of patients. (2) The comparison of clinical stages I:II showed a P value < 0.05. (3) The comparison of survival rates of CR:PR:P showed a P value < 0.05 and < 0.001, respectively. (4) There was no statistically significant difference in the four treatment protocols. But the multitherapy group was better. (5) Before the RT, four cycles of CT showed a better result than that of 1-3 cycles.

Adolescent↗
PubMed1989

[X-ray diagnosis of multiple epiphyseal dysplasia (a report of 3 cases from the same family)].

This is a case report of 3 cases from the same family with multiple epiphyseal dysplasia. The disease is an uncommon congenital dominant hereditary disease of the bone characterized by multiple and symmetrical skeletal involvement with retardation of epiphyseal development, accompanied by irregularity and shortening of toes and fingers and yet still maintaining the normal proportion between the trunk and extremities. The intelligence is not affected. In the adult patients, sloping of distal tibial articular surface associated with degenerative changes of both hip joints is a reliable diagnostic sign. The aforementioned X-ray signs are helpful to distinguish this condition from other chondrodysplasia diseases.

Adolescent↗
PubMedDate not supplied

A method of radio-frequency inhomogeneity correction for brain tissue segmentation in MRI.

An automatic method of correcting radio-frequency (RF) inhomogeneity in magnetic resonance images is presented. The method considers that image intensity variation due to radio-frequency inhomogeneity contains not only low frequency components, but also high frequency components. The variation is regarded as a multiplication of low frequency (capacity variation of coil) and the frequency of object (true image). The efficiency of the proposed method is illustrated with the aid of both phantom and physical images. The impact of the inhomogeneity correction on brain tissue segmentation is studied in detail. The results show significant improvement of the tissue segmentation after inhomogeneity correction.

Brain↗