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Biomedical subjects

M Fang

Publications and source records attributed to M Fang.

At least 55 records · Page 3Linked to original sources
PubMed2000

Study on the effect of ligustrazine on hematopoietic reconstitution in bone marrow transplantation mice.

To explore the effects of ligustrazine on hematopoietic reconstitution and its mechanism after bone marrow transplantation (BMT), the allogenic BMT mice were given intra-abdominal injection of 2 mg ligustrazine twice a day. On the 1st, 7th, 14th, and 28th day after BMT, peripheral blood cells and bone marrow nuclear cells (BMNC) were counted, and the histological features were evaluated. On the 7th, 14th, 21st day after BMT, CXCR4 expression on the BMNC was assayed. The results showed that peripheral blood cell counts and BMNC counts in ligustrazine-treated group on the 7th, 14th, 28th day were higher than those in BMT group (P < 0.01 or P < 0.05). The percentage of hematopoietic tissue volume, fat tissue hyperplasia and congestion and dilation degree of microvessel in ligustrazine-treated group on the 7th, 14th, 21st, 28th day was higher than those in BMT group. The CXCR4 expression levels in ligustrazine-treated group were higher than in BMT group (P < 0.01 or P < 0.05) on the 7th and 14th day, and were lower than in BMT group on the 21st day (P < 0.01). It is concluded that the ligustrazine can accelerate hematopoietic reconstruction, enhance growth of hematopoietic tissues and promote the repair of microvessels. The CXCR4 expression levels on BMNC may be responsible for the effect of ligustrazine.

Animals↗
PubMed2000

The relationship between ankle plantar flexor muscle moments and knee compressive forces in subjects with and without pain.

OBJECTIVE: The purpose of this study was to compare the compressive knee joint reaction force and ankle plantar flexor muscle moment during the terminal stance phase in symptomatic osteoarthritic and non-symptomatic subjects.DESIGN. The study design was a comparative investigation of walking patterns.BACKGROUND. Patients with knee osteoarthritic symptoms may employ altered gait patterns to reduce the loading of painful joints. Speculation is that decreased ankle plantar flexor moments in the terminal stance phase may be an attempt to minimize compressive knee joint reaction forces.METHODS. Twenty community-dwelling men (52-83 years old), ten with knee osteoarthritis and ten non-symptomatic, were studied while walking across a walkway containing two force plates at a comfortable speed. Retroreflective markers were placed in accordance with the Helen Hayes marker system and recorded with six 120 Hz cameras. Three-dimensional kinematics and kinetics were computed.RESULTS. Group means for gait velocity, peak ankle plantar flexor moment and compressive knee joint reaction force were significantly less for the osteoarthritic group relative to the non-symptomatic group. When accounting for the decreased velocity in the osteoarthritic group, however, no group differences were observed. There were significant correlations between all three gait parameters (r>0.75), but peak ankle plantar flexor moment was the greatest predictor of compressive knee joint reaction force.CONCLUSIONS. While no group differences were found for compressive knee joint reaction forces when accounting for gait velocity, it appears that subjects with osteoarthritis utilize gait velocity as a mechanism to reduce compressive knee joint reaction forces. RelevanceAn understanding of compressive knee joint reaction forces is important to the understanding of the disabling effects of knee osteoarthritis on physical function and to the understanding of appropriate and safe interventions to improve not only global parameters (e.g., pain, gait velocity), but also to "re-program" the locomotor pattern to develop "normal" muscle moments without increasing compressive knee joint reaction forces to painful levels.

Age Factors↗
PubMed2000

Dexras1: a G protein specifically coupled to neuronal nitric oxide synthase via CAPON.

Because nitric oxide (NO) is a highly reactive signaling molecule, chemical inactivation by reaction with oxygen, superoxide, and glutathione competes with specific interactions with target proteins. NO signaling may be enhanced by adaptor proteins that couple neuronal NO synthase (nNOS) to specific target proteins. Here we identify a selective interaction of the nNOS adaptor protein CAPON with Dexras1, a brain-enriched member of the Ras family of small monomeric G proteins. We find that Dexras1 is activated by NO donors as well as by NMDA receptor-stimulated NO synthesis in cortical neurons. The importance of Dexras1 as a physiologic target of nNOS is established by the selective decrease of Dexras1 activation, but not H-Ras or four other Ras family members, in the brains of mice harboring a targeted genomic deletion of nNOS (nNOS-/-). We also find that nNOS, CAPON, and Dexras1 form a ternary complex that enhances the ability of nNOS to activate Dexras1. These findings identify Dexras1 as a novel physiologic NO effector and suggest that anchoring of nNOS to specific targets is a mechanism by which NO signaling is enhanced.

Adaptor Proteins, Signal Transducing↗
PubMed2000

A hierarchical neural network algorithm for robust and automatic windowing of MR images.

A novel hierarchical neural network based algorithm for automatic adjustment of display window width and center for a wide range of magnetic resonance (MR) images is presented in this paper. The algorithm consists of a feature generator utilizing both wavelet histogram and compact spatial statistical information computed from a MR image, a competitive layer based neural network for clustering MR images into different subclasses, two pairs of a radial basis function (RBF) network and a bi-modal linear estimator for each subclass, as well as a data fusion process using estimates from both estimators to compute the final display parameters. Both estimators can adapt to new kinds of MR images simply by training them with those images, which make the algorithm adaptive and extendable. The RBF based estimator performs very well for images that are similar to those in the training data set. The bi-modal linear estimator provides reasonable estimations for a wide range of images that may not be included in the training data set. The data fusion step makes the final estimation of the display parameters accurate for trained images and robust for the unknown images. The algorithm has been tested on a wide range of MR images and has shown satisfactory results.

Algorithms↗
PubMed2000

Cardiolipin provides specificity for targeting of tBid to mitochondria.

Recent evidence supports the theory that mitochondrial homeostasis is the key regulatory step in apoptosis through the actions of members of the Bcl-2 family. Pro-apoptotic members of the family, such as Bax, Bad and Bid, can induce the loss of outer-membrane integrity with subsequent redistribution of pro-apoptotic proteins such as cytochrome c that are normally located in the intermembrane spaces of mitochondria. The anti-apoptotic members of the family, such as Bcl-2 and Bcl-XL, protect the integrity of the mitochondrion and prevent the release of death-inducing factors. Bid normally exists in an inactive state in the cytosol, but after cleavage by caspase 8, the carboxy-terminal portion (tBid) moves from cytosol to mitochondria, where it induces release of cytochrome c. Here we address the question of what mediates specific targeting of tBid to the mitochondria. We provide evidence that cardiolipin, which is present in mitochondrial membranes, mediates the targeting of tBid to mitochondria through a previously unknown three-helix domain in tBid. These findings implicate cardiolipin in the pathway for cytochrome c release.

Apoptosis↗
PubMed2000

Induction of apoptosis and activation of the caspase cascade by anti-EGF receptor monoclonal antibodies in DiFi human colon cancer cells do not involve the c-jun N-terminal kinase activity.

We previously reported that exposure of DiFi human colon cancer cells to the anti-epidermal growth factor (EGF) receptor monoclonal antibody (mAb) 225 resulted in apoptosis, but the mechanisms remain to be elucidated. In the present study, we investigated the effects of a panel of four anti-EGF receptor mAbs, each of which binds to different epitopes of the EGF receptor in DiFi cells, on the induction of apoptosis. We found that each of these mAbs induced apoptosis in DiFi cells. Exposure of DiFi cells to mAb 225 activated the initiation caspase-8, which was detectable between 8 and 16 h after exposure of the cells to the antibody. There was also an activation of the initiation caspase-9, which lagged a few hours behind the activation of caspase-8. Exposure of DiFi cells to mAb 225 also activated the execution caspase-3, which was accompanied temporally by evidence of cleavage of a well-characterized caspase-3 substrate, poly(ADP)ribosepolymerase (PARP). Pre-exposure of the cells to the caspase-3-specific inhibitor DEVD-CHO partially reduced the mAb 225-induced PARP cleavage and apoptosis, whereas pre-exposure of the cells to the caspase pan-inhibitor z-VAD-fmk completely inhibited mAb 225-induced apoptosis. Caspases-3, -8 and -9 were not activated in the cell lines in which mAb 225 only induced G1 phase arrest of the cell cycle. In contrast to the apoptosis of DiFi cells induced by ultraviolet irradiation, which strongly activated the c-jun N-terminal kinase-1 (JNK1) and the caspase cascade, mAb 225-induced apoptosis and activation of the caspase cascade in DiFi cells were not associated with activation of JNK1.

Adenocarcinoma↗
PubMed2000

Mutagenicity of recombinant antihemophilic factor (GC-gamma AHF).

This study was carried out to evaluate the mutagenic potential of recombinant antihemophilic factor VIII (GC-gamma AHF). Salmonella typhimurium (S. typhimurium) reversion assay with/without histidine moiety, chromosomal aberration assay on Chinese hamster lung (CHL) fibroblast cells and in vivo micronucleus assay using mouse bone marrow cells and supravital micronucleus assay using peripheral blood were performed. GC-gamma AHF containing histidine did show inconsistent and irregular mutagenic effects on S. typhimurium TA98, TA100, TA1535 and TA1537 both in the absence and presence of the metabolic activation system, however, GC-gamma AHF without histidine showed no mutagenic effects regardless of the metabolic activation system, thus suggesting that the histidine moiety in GC-gamma AHF might cause inconsistent mutagenic effect. Also GC-gamma AHF did not increase the number of cells having structural or numerical chromosome aberration in the cytogenetic test. In classical and supravital micronucleus assay, no significant increases were observed in the occurrence of micronucleated polychromatic erythrocytes and micronucleated peripheral lymphocytes in male ICR mice. These results strongly indicate that GC-gamma AHF has no genetic toxicity under these experimental conditions.

Animals↗
PubMed2000

Identification of a novel family of nonclassic yeast phosphatidylinositol transfer proteins whose function modulates phospholipase D activity and Sec14p-independent cell growth.

Yeast phosphatidylinositol transfer protein (Sec14p) is essential for Golgi function and cell viability. We now report a characterization of five yeast SFH (Sec Fourteen Homologue) proteins that share 24-65% primary sequence identity with Sec14p. We show that Sfh1p, which shares 64% primary sequence identity with Sec14p, is nonfunctional as a Sec14p in vivo or in vitro. Yet, SFH proteins sharing low primary sequence similarity with Sec14p (i.e., Sfh2p, Sfh3p, Sfh4p, and Sfh5p) represent novel phosphatidylinositol transfer proteins (PITPs) that exhibit phosphatidylinositol- but not phosphatidylcholine-transfer activity in vitro. Moreover, increased expression of Sfh2p, Sfh4p, or Sfh5p rescues sec14-associated growth and secretory defects in a phospholipase D (PLD)-sensitive manner. Several independent lines of evidence further demonstrate that SFH PITPs are collectively required for efficient activation of PLD in vegetative cells. These include a collective requirement for SFH proteins in Sec14p-independent cell growth and in optimal activation of PLD in Sec14p-deficient cells. Consistent with these findings, Sfh2p colocalizes with PLD in endosomal compartments. The data indicate that SFH gene products cooperate with "bypass-Sec14p" mutations and PLD in a complex interaction through which yeast can adapt to loss of the essential function of Sec14p. These findings expand the physiological repertoire of PITP function in yeast and provide the first in vivo demonstration of a role for specific PITPs in stimulating activation of PLD.

Base Sequence↗
PubMed2000

Perforation of jejunal diverticulum: case report and review of literature.

We report the case of a 90-year-old woman, previously diagnosed with jejunal and colonic diverticula, who presented with left lower quadrant abdominal pain suggesting either colonic diverticulitis or ischemic colitis. A computed tomography scan revealed a perforated jejunal diverticulum with abscess formation. The patient promptly was treated surgically without complications. A review of the literature indicates the rarity of perforation of jejunal diverticula and the difficulty of early diagnosis. We discuss the etiology, pathogenesis, diagnosis, and management of this rare entity. It is important for primary care physicians to be familiar with this disease. Delay in work-up often results in catastrophic consequences.

Abdominal Pain↗
PubMed2000

[The application of submental island flap in head and neck surgery].

OBJECTIVE: This article discusses the anatomy, surgical procedure,indication, advantages and disadvantages of the submental island flap in reconstruction of the defects after head and neck tumor surgery, based on our clinical experience. METHODS: The submental island flap was transferred with the submental vessels(A/V) as pedicle. In harvesting the flap, the flap was raised commencing from the contralateral side, dissecting all tissues off the mylohyoid muscles. Submandibular triangle dissection was taken until the facial artery and the facial vein. Then the submandibular gland and submandibular nodes were removed and submental vessels were left. This produces a large skin paddle which can be tunnelled to its recipient site. RESULTS: From Aug. 1998 to Oct. 1999, 16 submental island flaps were performed in our department. 15 flaps survived well and 1 flap failed, with a success rate of 15/16 (93.8%). CONCLUSION: The submental island flap is appropriate for primary reconstruction of the defect after various head and neck tumor surgery. It has a long and reliable pedicle, rapid and simple to raise and free from vessel anastomosis. It leaves a well hidden donor site. However, it can't be applied to these cases whose donor site had been radiated before surgery and whose submental and submandibular triangles lymph nodes were positive.

English Abstract↗
PubMed1999

Affinity capillary electrophoresis coupled with on-line microdialysis by attachable electrode.

This paper developed a new affinity capillary electrophoresis method coupled with on-line microdialysis using attachable electrodes in order to study the interaction of biomacromolecules with their small molecule ligands in the desired physiological conditions. The sampling mechanism was discussed and the experimental conditions were optimized. The affinity constant of sulfamethoxazole (SMZ) with bovine serum albumin (BSA) was determined with homemade equipment. The method is simple and practical.

Calibration↗
PubMed1999

Effects of lime amendment on availability of heavy metals and maturation in sewage sludge composting.

A batch composting study was performed to evaluate the feasibility of co-composting sewage sludge with lime, aiming at reducing the availability of heavy metals in the sludge compost. Sewage sludge with sawdust as bulking agent was amended with lime at 0, 0.63, 1.0, and 1.63% w/w, and composted for 100 days in laboratory batch reactors. The changes in temperature, pH, electrical conductivity (EC), and extractable heavy metal contents were measured while compost maturity was determined by C/N(organic) and cress seed germination during the composting period. Liming raised pH of compost effectively at the initial stage of composting and caused a decrease in EC through precipitation of soluble ions. Lime amendment also significantly reduced water-soluble and Diethylene triamine pentracetic acid (DTPA)-extractable metal contents. The maximum reductions were 60 and 40% for Cu, 80 and 40% for Mn, 55 and 10% for Zn, and 20 and 25% for Ni at the end of the composting period for the lime-amended sludge as compared to the control. In spite of the inhibitory effect of lime amendment on the decomposition activity of sewage sludge, all treatments reached maturation after 63 days of composting as indicated by the results of C/N(organic) ratio and cress seed germination test results. A lime amendment of < or =1.0% is recommended to co-compost with sewage sludge.

Journal Article↗
PubMed1999

A novel local PCA-based method for detecting activation signals in fMRI.

A novel local principal component analysis (LPCA) technique is presented for activation signal detection in functional magnetic resonance imaging (fMRI) without explicit knowledge about the shape of the model activation signal. Unlike the traditional PCA methods, our LPCA algorithm is based on a measure of separation between two clusters formed by the signal segments in active periods and inactive periods, which is computed in an eigen-subspace. In addition, we only applied PCA to the temporal sequence of each individual voxel instead of applying PCA to the fMRI data set. In our algorithm, we first applied a linear regression procedure to alleviate the baseline drift artifact. Then, the baseline-corrected temporal signals were partitioned into active and inactive segments according to the paradigm used for the fMRI data acquisition. Principal components were computed from all these segments for each voxel by PCA. By projecting the segments of each voxel onto a linear subspace formed by the corresponding most dominant principal components, two separate clusters were formed from active and inactive segments. An activation measure was defined based on the degree of separation between these two clusters in the projection space. We show experimental results on the activation signal detection from various sets of fMRI data with different types of stimulation by using the proposed LPCA algorithm and the standard t-test method for comparison. Our experiments indicate that the LPCA algorithm in general provides substantial signal-to-noise ratio improvement over the t-test method.

Algorithms↗
PubMed1999

A new variational shape-from-orientation approach to correcting intensity inhomogeneities in magnetic resonance images.

A new intensity inhomogeneity correction algorithm based on a variational shape-from-orientation formulation is presented. Unlike most previous methods, the proposed algorithm is fully automatic, widely applicable and very efficient. Since no prior classification knowledge about the image is assumed in the proposed algorithm, it can be applied to correct intensity inhomogeneities for a wide variety of medical images. In this paper, a finite-element method is used to model the smooth bias-field function. Orientation constraints for the bias-field function are computed at the nodal locations of the regular discretization grid away from the boundary between different class regions. The selection of reliable orientation constraints is facilitated by the goodness of fit of a first-order polynomial model to the neighborhood of each nodal location. The automatically selected orientation constraints are integrated in a regularization framework, which leads to minimization of a convex and quadratic energy function. This energy minimization is accomplished by solving a linear system with a large, sparse, symmetric and positive semi-definite stiffness matrix. We employ an adaptive preconditioned conjugate-gradient algorithm to solve the linear system very efficiently. Experimental results on a variety of magnetic resonance images are given to demonstrate the effectiveness and efficiency of the proposed algorithm.

Algorithms↗
PubMed1998

Suppression of leu-500 mutation in topA+ Salmonella typhimurium strains. The promoter relay at work.

Suppression of leu-500 mutation in Salmonella typhimurium topA- strains has been one of the most fascinating examples for the DNA supercoiling effect on transcription initiation control. Previous studies have indicated possible involvement of transcription-driven DNA supercoiling in the activation of the leu-500 promoter in topA- strains. Our recent studies have shown that ilvIH transcription activity located 1.9 kilobase pairs upstream is the initial supercoiling signal for leu-500 activation via a promoter relay mechanism. In the present communication, we show that the ilvIH transcription activity-initiated promoter relay can result in leu-500 activation in topA+ strains. In addition, suppression of the chromosomal leu-500 mutation correlates with the transcription activities of ilvIH and leuO rather than the TopA level in the topA+ strain. It appears that the leu-500 suppression in a topA- strain is due to the constant ilvIH transcription activity.

Chromosomes, Bacterial↗
PubMed1998

Phospholipase D activity is required for suppression of yeast phosphatidylinositol transfer protein defects.

Yeast phosphatidylinositol transfer protein (Sec14p) function is essential for production of Golgi-derived secretory vesicles, and this requirement is bypassed by mutations in at least seven genes. Analyses of such 'bypass Sec14p' mutants suggest that Sec14p acts to maintain an essential Golgi membrane diacylglycerol (DAG) pool that somehow acts to promote Golgi secretory function. SPO14 encodes the sole yeast phosphatidylinositol-4,5-bisphosphate-activated phospholipase D (PLD). PLD function, while essential for meiosis, is dispensable for vegetative growth. Herein, we report specific physiological circumstances under which an unanticipated requirement for PLD activity in yeast vegetative Golgi secretory function is revealed. This PLD involvement is essential in 'bypass Sec14p' mutants where normally Sec14p-dependent Golgi secretory reactions are occurring in a Sec14p-independent manner. PLD catalytic activity is necessary but not sufficient for 'bypass Sec14p', and yeast operating under 'bypass Sec14p' conditions are ethanol-sensitive. These data suggest that PLD supports 'bypass Sec14p' by generating a phosphatidic acid pool that is somehow utilized in supporting yeast Golgi secretory function.

Carrier Proteins↗
PubMed1998

The contribution of lipids and lipid metabolism to cellular functions of the Golgi complex.

The history of the Golgi complex now reaches its 100 year anniversary. Over the past several decades, tremendous effort has gone into cataloguing Golgi resident proteins, measuring the lipid compositions of Golgi membranes, and in elucidating the pathways by which proteins and lipids traffic through this unique organelle. Only in the past 8 years or so has experimental scrutiny extended to the investigation of how lipids and proteins cooperate to endow the Golgi with its various capabilities regarding protein/lipid transport and sorting. In this chapter we review some of the most recent advances in deciphering the functional interfaces between lipids and proteins of the Golgi complex.

Animals↗