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Biomedical subjects

Jun Wang

Publications and source records attributed to Jun Wang.

At least 487 records · Page 27Linked to original sources
PubMed2003

Pathogenesis of increased risk of thrombosis in cancer.

Since the observations of Trousseau, not only has the association of cancer and thrombosis been widely recognized but its pathogenesis is now better understood. Attention to the tumor cell as an important source of procoagulants has also contributed to our knowledge of this problem. Tumor cells express tissue factor (TF) and a cancer procoagulant (CP). TF is dormant in the living cell. However, it is activated during apoptosis of the cell, initiating the coagulation cascade and leading to thrombin generation. Because increased apoptosis occurs during treatment with chemotherapeutic agents, hormones, radiation, and hematopoietic growth factors, as well as when there is rapid tumor proliferation, the thrombosis risk is heightened accordingly. These developments have obvious basic and clinical implications.

Apoptosis↗
PubMed2003

Hyperviscosity in polycythemia vera and other red cell abnormalities.

Thrombosis is a major cause of mortality and morbidity in polycythemia vera (PV). The wide range of thrombotic events reflects the complex picture in PV. There are multiple factors involved in thrombogenesis in this disease, including increased hematocrit, thrombocytosis, impaired fibrinolytic activity, platelet activation, leukocyte activation, endothelial damage, interactions between platelets and endothelium, various modalities of therapy, and increased in whole-blood viscosity. Among them, the increase in blood viscosity, and hence the impairment of blood flow, is the major factor. In this article, the role of hyperviscosity in PV is reviewed. A high hematocrit occurs under PV and many other conditions with abnormal red blood cell aggregation. The impaired capillary blood flow results in neurological manifestations and increased bleeding risk in PV. Thrombotic complications can also occur in both arteries and veins and manifest as stroke, myocardial infarction, deep vein thrombosis, or pulmonary embolism. The hemodynamic principle is aptly applied in the management of PV. The most important objective is the reduction of the patient's hematocrit.

Blood Viscosity↗
PubMed2003

Rheological abnormalities and thromboembolic complications in heart disease: spontaneous echo contrast and red cell aggregation.

The role of abnormal rheological changes in the pathogenesis of thromboembolism has received much attention in recent years, especially in the field of cardiology. Such changes are sometimes seen in an echocardiogram as a smokelike haze known as spontaneous echo contrast (SEC). The presence and severity of SEC correlate with dilated cardiac chambers and the incidence of thromboembolic complications. It is caused by increased red cell aggregation and increased fibrinogen levels, both of which are known risk factors for thrombosis. Although not used clinically, measurements of red cell aggregation can be made in research settings. This can provide findings that give insight into factors causing increased red cell aggregation. A small series of patients with angina pectoris was studied with the Myrenne aggregometer for red cell aggregation. The results, which show correlation between the plasma fibrinogen and triglyceride levels, are presented. As yet, there are only a few therapeutic guidelines for the correction of abnormally high fibrinogen levels in patients at risk.

Blood Viscosity↗
PubMed2003

DNA microarray for identification of the herb of dendrobium species from Chinese medicinal formulations.

A DNA microarray for detecting processed medicinal Dendrobium species (Herba Dendrobii) was constructed by incorporating the ITS1-5.8S-ITS2 sequences of 16 Dendrobium species on a glass slide. Using fluorescence-labeled ITS2 sequences as probes, distinctive signals were obtained for the five medicinal Dendrobium species listed in the Chinese Pharmacopoeia. The established microarray was able to detect the presence of D. nobile in a Chinese medicinal formulation containing nine herbal components.

DNA, Plant↗
PubMed2003

Mucocele of the glands of Blandin-Nuhn: clinical and histopathologic analysis of 26 cases.

We investigated the clinical and histopathologic features of 26 cases of mucocele of the glands of Blandin-Nuhn. There was a female predominance, and most patients were younger than 20 years. Fifteen patients first visited a medical doctor and 9 visited a dentist before being referred to our department. The average duration from the time the lesion was first noticed to the patient's visit was 3.6 months. All lesions were located on the ventral surface of the tongue. In 17 patients, mucoceles were seen at the tip of the tongue, whereas 9 lesions occurred more posteriorly. Lesions were situated at the midline in 19 patients and laterally in 7 patients. All lesions presented as an exophytic mass, often with a polypoid appearance. All mucoceles were histopathologically of the extravasation type, suggesting that trauma may represent a frequent initiating factor.

Adolescent↗
PubMed2003

Post-transcriptional cosuppression of Ty1 retrotransposition.

To determine whether homology-dependent gene silencing or cosuppression mechanisms underlie copy number control (CNC) of Ty1 retrotransposition, we introduced an active Ty1 element into a naïve strain. Single Ty1 element retrotransposition was elevated in a Ty1-less background, but decreased dramatically when additional elements were present. Transcription from the suppressing Ty1 elements enhanced CNC but translation or reverse transcription was not required. Ty1 CNC occurred with a transcriptionally active Ty2 element, but not with Ty3 or Ty5 elements. CNC also occurred when the suppressing Ty1 elements were transcriptionally silenced, fused to the constitutive PGK1 promoter, or contained a minimal segment of mostly TYA1-gag sequence. Ty1 transcription of a multicopy element expressed from the GAL1 promoter abolished CNC, even when the suppressing element was defective for transposition. Although Ty1 RNA and TyA1-gag protein levels increased with the copy number of expressible elements, a given element's transcript level varied less than twofold regardless of whether the suppressing elements were transcriptionally active or repressed. Furthermore, a decrease in the synthesis of Ty1 cDNA is strongly associated with Ty1 CNC. Together our results suggest that Ty1 cosuppression can occur post-transcriptionally, either prior to or during reverse transcription.

Adenosine Triphosphatases↗
PubMed2003

Dietary diethylstilbestrol but not genistein adversely affects rat testicular development.

Isoflavones, including genistein, contribute to the health benefits of a soy diet. However, the estrogenic activity of genistein suggests that there may be adverse effects on reproductive tract development. We investigated the potential of exposure to genistein (250 and 1000 mg/kg diet) and the synthetic estrogen and known male reproductive toxicant, diethylstilbestrol (DES, 75 micro g/kg diet) from d 21 to d 35 to alter rat testicular development. These dietary genistein concentrations resulted in serum concentrations that approximate or exceed concentrations in Asian men on a soy-containing diet. DES exposure reduced testicular weights, altered morphology and increased apoptosis in the seminiferous tubules. The effects of DES were accompanied by a reduction in androgen receptor (AR) protein concentrations, predominantly localized to Sertoli cells. Increased expression and immunostaining for the epidermal growth factor receptor (EGFR) and its downstream extracellular signal-regulated kinases (ERK) 1 and 2 in spermatagonia and spermatocytes were also observed. Immunohistochemical analysis of serial sections demonstrated that greater EGFR expression correlated with increased cellular proliferation, rather than apoptosis, and reflected impaired testicular development in DES-treated rats. Genistein in the diet did not significantly alter testicular weights, morphology, AR, EGFR and ERK expression or apoptosis. However, the higher concentration significantly reduced testicular aromatase activity, an effect that may contribute to reduced estrogen concentrations and suppression of prostate cancer development. These data suggest that exposure to genistein in the diet at concentrations that result in serum concentrations at the upper limit of humans consuming soy products does not adversely affect testicular development, but may provide health benefits.

Animals↗
PubMed2003

Reduction of protein sequence complexity by residue grouping.

It is well known that there are some similarities among various naturally occurring amino acids. Thus, the complexity in protein systems could be reduced by sorting these amino acids with similarities into groups and then protein sequences can be simplified by reduced alphabets. This paper discusses how to group similar amino acids and whether there is a minimal amino acid alphabet by which proteins can be folded. Various reduced alphabets are obtained by reserving the maximal information for the simplified protein sequence compared with the parent sequence using global sequence alignment. With these reduced alphabets and simplified similarity matrices, we achieve recognition of the protein fold based on the similarity score of the sequence alignment. The coverage in dataset SCOP40 for various levels of reduction on the amino acid types is obtained, which is the number of homologous pairs detected by program BLAST to the number marked by SCOP40. For the reduced alphabets containing 10 types of amino acids, the ability to detect distantly related folds remains almost at the same level as that by the alphabet of 20 types of amino acids, which implies that 10 types of amino acids may be the degree of freedom for characterizing the complexity in proteins.

Amino Acid Sequence↗
PubMed2003

An optimization algorithm for intensity modulated radiotherapy--the simulated dynamics with dose-volume constraints.

We have developed a new method for optimization in intensity modulated radiation therapy (IMRT) that makes use of simulated dynamics in a classical system of interacting particles. An analogy is drawn between intensity profile optimization in IMRT and relaxation to the equilibrium configuration in a dynamic system. The intensities of beamlets are equivalent to the positions of the virtual particles. The potential energy of the system is defined by the objective function, which determines the equations of motion for the virtual particles. In this paper, we present the implementation of dose constraints and dose-volume constraints. Our strategy is to optimize the dose to the planned target volume (PTV) while keeping all constraints to the organs at risk (OARs) satisfied rigorously. A simple quadratic objective function is used that only includes terms for PTV voxels. By this approach, no additional parameters other than that for prescribing desired dose and constraints, such as importance factors, are needed. The hard constraints that require non-negative beamlet intensities and that the dose at any voxel in an OAR cannot exceed a maximum tolerance, are implemented as semi-transmittable potential barriers of infinite height. Dose-volume constraints are handled by placing hard constraints on partial volumes. Handling of the clinically applied constraints was tested using phantoms and clinical cases. Our results show that the dose-volume histogram (DVH) type of plan prescription can be fulfilled with satisfactory PTV coverage. In addition to the convenience of implementation, our method can achieve a high computational efficiency with the understanding of the dynamic behavior of the system.

Algorithms↗
PubMed2003

Beam orientation optimization for IMRT by a hybrid method of the genetic algorithm and the simulated dynamics.

We have developed a new method for beam orientation optimization in intensity-modulated radiation therapy (IMRT). The problem of beam orientation optimization in IMRT is solved by a decoupled two-step iterative process: (1) optimization of the intensity profiles for given beam configurations; (2) selection of optimal beam configurations based on the ranking by an objective function score for the results of the intensity profile optimization. The simulated dynamics algorithm is used for the intensity profile optimization. This algorithm enforces both the hard constraints and dose-volume constraints. A genetic algorithm is used to select beam orientation configurations. The method has been tested for both a simulated and clinical case, and the results show that beam orientation optimization significantly improved IMRT plans within a time period that is clinically acceptable. The results also show the dependence of the optimal orientation configurations on the prescribed constraints. In addition, beam orientation optimization by the method described here can provide multiple plans with similar dose distributions. This degeneracy characteristic can be exploited to our advantage in introducing additional planning objectives, e.g., the smoothness of intensity profiles, for the selection of the optimal plan among the degenerate configurations for treatment delivery.

Algorithms↗
PubMed2003

Global and robust stability of interval Hopfield neural networks with time-varying delays.

In this paper, we investigate the problem of global and robust stability of a class of interval Hopfield neural networks that have time-varying delays. Some criteria for the global and robust stability of such networks are derived, by means of constructing suitable Lyapunov functionals for the networks. As a by-product, for the conventional Hopfield neural networks with time-varying delays, we also obtain some new criteria for their global and asymptotic stability.

Algorithms↗
PubMed2003

Novel stability criteria for delayed cellular neural networks.

In this paper, a new sufficient condition is given for the global asymptotic stability and global exponential output stability of a unique equilibrium points of delayed cellular neural networks (DCNNs) by using Lyapunov method. This condition imposes constraints on the feedback matrices and delayed feedback matrices of DCNNs and is independent of the delay. The obtained results extend and improve upon those in the earlier literature, and this condition is also less restrictive than those given in the earlier references. Two examples compared with the previous results in the literatures are presented and a simulation result is also given.

Algorithms↗
PubMed2003

Inhibition of thrombosis in melanoma allografts in mice by endogenous mast cell heparin.

An unexplained paradox of malignant melanoma is the apparent failure of the blood within the tumor to clot despite the presence of multiple factors that should promote blood clotting. Here we present histochemical evidence that human and murine melanomas are extensively infiltrated by abundant mast cells. Because mast cells contain the natural anticoagulant heparin, the present studies were aimed at defining the role of mast cell heparin in preventing the blood from clotting within B16 melanoma grafts in C57BL/6 J mice. Mice bearing B16 melanoma grafts were treated with non-specific or specific inhibitors of mast cell heparin (protamine or heparinase, respectively). After the drug treatment there was histologic and functional evidence of selective thrombosis of the blood vessels within the protamine and heparinase treated melanoma grafts. A similar, high degree of thrombosis was also observed in B16 tumors grown in transgenic NDST-2 knockout mice bearing a targeted disruption in the gene coding for mast cell heparin synthesis. The tumors grown in the protamine-treated animals were significantly smaller than the tumors from control (untreated mice). By contrast, the tumors treated with heparinase or grown in the NDST-2 knockout mice were significantly larger than the tumors from control (untreated) mice. We conclude that the intrinsic procoagulant properties of malignant melanoma are neutralized in vivo by the anticoagulant properties of endogenous heparin produced by mast cells that naturally infiltrate the tumor. Our results also suggest that thrombosis and hemostasis within melanoma may play a complex role in modulating the growth of the tumor.

Amidohydrolases↗
PubMed2003

Numerical characterization and similarity analysis of DNA sequences based on 2-D graphical representation of the characteristic sequences.

Based on the classifications of the four nucleic acid bases, He and Wang reduced a DNA sequence to three binary sequences, which are called the characteristic sequences (J. Chem. Inf. Comput. Sci. 42 (2002) 1080). In this paper, we associate each characteristic sequence with a (b)L / (b)L matrix by giving a 2-D 'two horizontal lines' graphical representation, and thus obtain a 3-component vector with entries being the sums of the maximal and minimal eigenvalues of the (b)L / (b)L matrices. The introduced vector results in more simple characterizations and comparisons among the coding sequences of exon 1 of beta-globin gene of eleven different species.

Animals↗
PubMed2003

Clinicopathologic study of mucosa-associated lymphoid tissue lymphoma in gastroscopic biopsy.

AIM: To explore and discuss the clinicopathologic characteristics of mucosa-associated lymphoid tissue (MALT) lymphoma in gastroscopic biopsy specimen. METHODS: A retrospective study of 26 cases of lymphoma diagnosed by gastroscopic biopsy during 1999 to 2001 from gastroscopy files of Xijing Hospital was made. The diagnostic criteria were adopted according to the new classification of non-Hodgkin's lymphoma. RESULTS: Twenty-six cases of primary gastric lymphoma consisting of 15 men and 11 women, aged between 23 to 76 years were recruited from 6 225 cases who received gastroscopy. All of them were diagnosed by both endoscopic findings and histological examinations. Histologically, 23 cases were MALToma (low grade) and 3 cases lymphoblastic lymphoma (high grade). Immunohistochemically, all cases were CD20 positive, while CK and EMA were negative. CONCLUSION: The majority of the cases of primary low-grade gastric lymphoma have morphologic and clinical features that justify their inclusion in the category of low-grade lymphoma of mucosa associated lymphoid tissue.

Adult↗
PubMed2003

Prospective study of biofeedback retraining in patients with chronic idiopathic functional constipation.

AIM: To determine the efficacy and long-term outcome of biofeedback treatment for chronic idiopathic constipation and to compare the efficacy of two modes of biofeedback (EMG-based and manometry-based biofeedback). METHODS: Fifty consecutive contactable patients included 8 cases of slow transit constipation, 36 cases of anorectic outlet obstruction and 6 cases of mixed constipation. Two modes of biofeedback were used for these 50 patients, 30 of whom had EMG-based biofeedback, and 20 had manometry-based biofeedback. Before treatment, a consultation and physical examination were done for all the patients, related information such as bowel function and gut transit time was documented, psychological test (symptom checklist 90, SCL90) and anorectic physiological test and defecography were applied. After biofeedback management, all the patients were followed up. The Student's t-test, chi-squared test and Logistic regression were used for statistical analysis. RESULTS: The period of following up ranged from 12 to 24 months (Median 18 months). 70 % of patients felt that biofeedback was helpful, and 62.5 % of patients with constipation were improved. Clinical manifestations including straining, abdominal pain, bloating, were relieved, and less oral laxative was used. Spontaneous bowel frequency and psychological state were improved significantly after treatment. Patients with slow and normal transit, and those with and without paradoxical contraction of the anal sphincter on straining, benefited equally from the treatment. The psychological status rather than anorectal test could predict outcome. The efficacy of the two modes of biofeedback was similar without side effects. CONCLUSION: This study suggests that biofeedback has a long-term effect with no side effects, for the majority of patients with chronic idiopathic constipation unresponsive to traditional treatment. Pelvic floor abnormalities and transit time should not be the selection criteria for treatment.

Adolescent↗
PubMed2003

Diagnostic and molecular evaluation of three iridovirus-associated salamander mortality events.

In 1998 viruses were isolated from tiger salamander larvae (Ambystoma tigrinum diaboli and A. tigrinum melanostictum) involved in North Dakota and Utah (USA) mortality events and spotted salamander (A. maculatum) larvae in a third event in Maine (USA). Although sympatric caudates and anurans were present at all three sites only ambystomid larvae appeared to be affected. Mortality at the North Dakota site was in the thousands while at the Utah and Maine sites mortality was in the hundreds. Sick larvae were lethargic and slow moving. They swam in circles with obvious buoyancy problems and were unable to remain upright. On the ventral surface, near the gills and hind limbs, red spots or swollen areas were noted. Necropsy findings included: hemorrhages and ulceration of the skin, subcutaneous and intramuscular edema, swollen and pale livers with multifocal hemorrhage, and distended fluid-filled intestines with areas of hemorrhage. Light microscopy revealed intracytoplasmic inclusions, suggestive of a viral infection, in a variety of organs. Electron microscopy of ultra thin sections of the same tissues revealed iridovirus-like particles within the inclusions. These viruses were isolated from a variety of organs, indicating a systemic infection. Representative viral isolates from the three mortality events were characterized using molecular assays. Characterization confirmed that the viral isolates were iridoviruses and that the two tiger salamander isolates were similar and could be distinguished from the spotted salamander isolate. The spotted salamander isolate was similar to frog virus 3, the type species of the genus Ranavirus, while the tiger salamander isolates were not. These data indicate that different species of salamanders can become infected and die in association with different iridoviruses. Challenge assays are required to determine the fish and amphibian host range of these isolates and to assess the susceptibility of tiger and spotted salamanders to heterologous virus isolates.

Amino Acid Sequence↗