Biomedical subjects

Y Kong

Publications and source records attributed to Y Kong.

At least 55 records · Page 3Linked to original sources

PubMed2000

Cellular gangliosides promote growth factor-induced proliferation of fibroblasts.

Cell surface gangliosides have been proposed as modulators of transmembrane signaling. In this study, we used two complementary approaches to investigate the function of cellular gangliosides in the response of mammalian fibroblasts to growth factors. First, inhibition of glucosyl ceramide synthase by a new specific inhibitor of d-l-threo-1-phenyl-2-hexadecanoylamino-3 -pyrrolidino-1-propanol-HC l (glucosylceramide synthase), which depletes cellular gangliosides at a concentration of 1 microm without causing an increase in ceramide levels, blocked epidermal growth factor-stimulated proliferation of fibroblasts. Similarly, responses to several other growth factors that activate receptor tyrosine kinases, including fibroblast growth factor, insulin-like growth factor-I, and platelet-derived growth factor, were inhibited by 50-100%. Conversely, enrichment of cellular gangliosides by preincubation of the mouse and human fibroblasts with exogenously added gangliosides enhanced growth factor-elicited cell proliferation. Novel findings of this study, distinguishing it from previous similar studies, include differential effects of preincubation versus continuous incubation of cells with gangliosides on growth factor-dependent cell proliferation and the growth factor-like action of NeuNAc alpha 2-3Gal beta 1-3GalNAc beta 1-4(NeuNAc alpha 2-3)Gal beta 1-4Glc beta 1-1Cer when cells are pretreated with the ganglioside.

3T3 Cells↗

PubMed2000

Pedicle morphology in thoracic adolescent idiopathic scoliosis: is pedicle fixation an anatomically viable technique?

STUDY DESIGN: A radiographic study of thoracic pedicle anatomy in a group of adolescent idiopathic scoliosis (AIS) patients. OBJECTIVE: To investigate the anatomic constraints of the thoracic pedicles and determine whether the local anatomy would routinely allow pedicle screw insertion at every level. SUMMARY OF BACKGROUND DATA: In spite of the clinical successes reported with limited thoracic pedicle screw-rod constructs for thoracic AIS, controversy exists as to the safety of this technique. MATERIAL AND METHODS: Twenty-nine patients with right thoracic AIS underwent preoperative thoracic CT scans and plain radiographs. Anatomic parameters were measured from T1 to T12. RESULTS: Information on 512 pedicles was obtained. The transverse width of the pedicles from T1 through T12 ranged from 4.6-8.25 mm. The medial pedicle to lateral rib wall transverse width from T1 through T2 ranged from 12.6 to 17.9 mm. Measured dimensions from the CT scans showed the actual pedicle width to be 1-2 mm larger than would have been predicted from the plain radiographs. Age, Risser grade, curve magnitude, and the amount of segmental axial rotation did not correlate with the morphology or size of the thoracic pedicles investigated. In no case would pedicle morphology have precluded the passage of a pedicle screw. CONCLUSION: Based on the data identified in this group of adolescent patients, it is reasonable to consider pedicle screw insertion at most levels and pedicle-rib fixation at all levels of the thoracic spine during the treatment of thoracic AIS.

Adolescent↗

PubMed2000

Prospective pulmonary function evaluation following open thoracotomy for anterior spinal fusion in adolescent idiopathic scoliosis.

STUDY DESIGN: Prospective study. OBJECTIVES: To prospectively evaluate sequential pulmonary function tests (PFTs) at a minimum 2-year follow-up after an open anterior spinal fusion (ASF) with instrumentation for thoracic AIS. SUMMARY OF BACKGROUND DATA: Anterior spinal fusion with instrumentation is currently undergoing evaluation as an alternative to posterior spinal fusion (PSF) for thoracic adolescent idiopathic scoliosis (AIS). However, the effect of an open thoracotomy on pulmonary function in these patients is unknown. METHODS: Fifty-one patients with thoracic AIS with an average age of 15+0 (range 11+2 to 20+5) had PFTs consisting of volume (FVC), flow (FEV-1), and total lung capacity (TLC). Parameters were obtained preoperatively, and at 3 months, 1 year, and a minimum 2-year follow-up. All patients had a single or double open thoracotomy with the diaphragm kept intact. Fusion levels ranged from T4 (most proximal) to L1 (most distal). The average preoperative thoracic coronal Cobb measurement was 53 degrees (range 38 degrees to 80 degrees ), and the average postoperative coronal measurement was 24 degrees (range 7 degrees to 49 degrees ). The average preoperative thoracic sagittal kyphosis (T5-T12) averaged 22 degrees (range 10 degrees to 58 degrees ), and the average postoperative sagittal kyphosis measured 29 degrees (range 7 degrees to 67 degrees ). RESULTS: There was a significant decline (P< or =0.05) in PFT absolute values (L) of 19%-FVC, 15%-FEV-1, and 11%-TLC at 3 months postoperatively with subsequent improvement and no statistical difference between preoperative and 2-year postoperative values. When evaluating percent predicted values, there was a statistical decline (P< or =0.05) at 3 months postoperatively averaging 19% FVC, 14% FEV-1, and 12% TLC. These values returned to within 94% to 96% of baseline by the 2-year follow-up visit, but were still statistically less than the preoperative values (P</=0.05). CONCLUSIONS: Pulmonary function following thoracotomy with ASF with instrumentation demonstrated a significant decline of 3-month postoperative PFT values, but returned to preoperative baseline absolute values (L) by the 2-year follow-up visit. The percent predicted values returned to within 95% of baseline 2 years postoperatively. Scoliosis surgeons should be aware of these findings when deciding upon the approach (anterior versus posterior) utilized for thoracic AIS.

Adolescent↗

PubMed2000

Cutting edge: differential constitutive expression of functional receptors for lysophosphatidic acid by human blood lymphocytes.

Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) from platelets and macrophages mediate T cell functions. Endothelial differentiation gene-encoded G protein-coupled receptors (Edg Rs) are specific for S1P (Edg-1, -3, -5, and -8 Rs) and LPA (Edg-2, -4, and -7 Rs). Human T cell tumors express many Edg Rs for both LPA and S1P. In contrast, human blood CD4+ T cells express predominantly Edg-4, and CD8+ T cells show only traces of Edg-2 and -5, by quantification of mRNA and Edg R Ags. LPA at 10-10-10-6 M suppressed significantly the secretion of IL-2 from anti-CD3 plus anti-CD28 Ab-challenged CD4+ T cells, but not CD8+ T cells. Monoclonal anti-Edg-4 R Ab, like LPA, suppressed stimulated IL-2 secretion from CD4+ T cells, but not CD8+ T cells. Constitutive expression of Edg-4 by CD4+, but not CD8+, human T cells accounts for differential functional responsiveness of the T cell subsets to LPA.

Adjuvants, Immunologic↗

PubMed2000

The winged-helix/forkhead protein myocyte nuclear factor beta (MNF-beta) forms a co-repressor complex with mammalian sin3B.

Winged-helix/forkhead proteins regulate developmental events in both invertebrate and vertebrate organisms, but biochemical functions that establish a mechanism of action have been defined for only a few members of this extensive gene family. Here we demonstrate that MNF (myocyte nuclear factor)-beta, a winged-helix protein expressed selectively and transiently in myogenic precursor cells of the heart and skeletal muscles, collaborates with proteins of the mammalian Sin3 (mSin3) family to repress transcription. Mutated forms of MNF-beta that fail to bind mSin3 are defective in transcriptional repression and in negative growth regulation, an overexpression phenotype revealed in oncogenic transformation assays. These data extend the known repertoire of transcription factors with which mSin3 proteins can function as co-repressors to include members of the winged-helix gene family. Transcriptional repression by MNF-beta-mSin3 complexes may contribute to the co-ordination of cellular proliferation and terminal differentiation of myogenic precursor cells.

Adenovirus E1A Proteins↗

PubMed2000

Paragonimus westermani: a cytosolic glutathione S-transferase of a sigma-class in adult stage.

We purified cytosolic glutathione S-transferase (GST) of adult Paragonimus westermani monitoring its activity with 1-chloro-2,4-dinitrobenzene (CDNB). The enzyme was purified 18.4-fold to electrophoretic homogeneity with 21% recovery rate through a three-step procedure. The purified enzyme (Pw28GST) has a subunit molecular weight of 28 kDa with an isoelectric point at 4.6. Monoclonal antibody (anti-Pw28GST) against Pw28GST did not cross-react with GSTs from other helminths. cDNA library was constructed in lambdaZAP II bacteriophage and screened with anti-Pw28GST. The corresponding gene containing a single open reading frame of 804 bp encoded 211 amino acids. The predicted amino acid sequence exhibited a higher homology with catalytic domain near N-terminus of class sigma GSTs (58%) than with schistosome 28-kDa GSTs (45-41%) or with class sigma GSTs themselves (33-31%). The sequence contained both Tyr-6 and Tyr-10 that are highly conserved in mammalian and helminth GSTs. The apparent K(m) value of a recombinant enzyme was 0.78 mM. Both native and recombinant enzymes showed the highest activity against CDNB, relatively weak activity against ethacrynic acid and reactive carbonyls, and no activity against epoxy-3-(p-nitrophenoxy)-propane. The activities were inhibited by bromosulfophthalein, cibacron blue, and albendazole, but not by praziquantel. These findings indicate that adult P. westermani has a class sigma GST.

Amino Acid Sequence↗

PubMed2000

Microbiology of the 'G-bacteria' in activated sludge.

This review discusses a group of bacteria, the 'G-bacteria', which have a distinctive morphology of cocci in tetrads, sheets or clusters, that are seen in large numbers in many activated sludge biomass samples. Isolates of 'G-bacteria' that have been grown axenically are phylogenetically diverse. The Gram-negative members include several alpha- and beta-proteobacteria, among which is the genus Amaricoccus, while the Gram-positive 'G-bacteria' contain several members of the actinobacteria. It is probable that other, as yet uncharacterized, 'G-bacteria' exist in activated sludge. The hypothesis that these 'G-bacteria' are detrimental to the process of enhanced biological phosphate removal by competing for substrates anaerobically with the phosphate-accumulating bacteria in such systems, based as it is largely on mixed-culture studies, receives little support from studies using those available in pure culture. The evidence on which these conclusions are founded is discussed, as are the arguments used to explain why these 'G-bacteria' all appear to thrive under conditions found in certain activated sludge systems.

Actinobacteria↗

PubMed2000

Reply

Explore the source record for details and available documents.

Journal Article↗

PubMed2000

Altered expression and functional profile of lysophosphatidic acid receptors in mitogen-activated human blood T lymphocytes.

Lysophosphatidic acid (LPA) from platelets and mononuclear phagocytes regulates T cell functions through endothelial differentiation gene-encoded G protein-coupled receptors (Edg Rs). Human blood unactivated CD4+ T cells express predominant ly Edg-4 LPA R over marginal levels of Edg-2 LPA R, as assessed by semiquantitative PCR and Western blots. After mitogen activation, the CD4+ T cells express Ed g-2 Rs at approximately one half the level of Edg-4 Rs. Secretion of IL-2 by unactivated Edg-4 R-predominant CD4+ T cells incubated with anti-CD3 plus anti-CD28 antibodies was suppressed significantly and by up to 60% by 10-10 M to 10-6 M LPA, whereas secretion of IL-2 by mitogen-activated Edg-2 R and Edg-4 R codominant CD4+ T cells was enhanced by up to twofold by the same concentrations of LPA. The possibility that the two Edg Rs transduce different LPA signals to CD4+ T cells was supported by findings that IL-2 secretion was inhibited by mouse anti-Edg-4 R monoclonal antibody, but enhanced by mouse anti-Edg-2 R monoclonal antibody. The separate effects of each LPA R were studied in Jurkat T cell transfectants expressing principally human Edg-2 Rs (Jurkat-T-2) or Edg-4 Rs (Jurkat-T-4) and stimulated with anti-CD3 plus phorbol myristate acetate. LPA and anti-Edg-4 R antibody suppressed IL-2 secretion by stimulated Jurkat-T-4 cells, whereas LPA and anti-Edg-2 R antibody enhanced IL-2 secretion by stimulated Jurkat-T-2 cells. Activation-induced alterations in the relative levels of Edg-2 and -4 Rs on CD4+ T cells thus reverse the effects of LPA on T cell receptor-stimulated generation of IL-2.

Humans↗

PubMed2000

Vasoactive intestinal peptide mediation of development and functions of T lymphocytes.

The first phase in investigating neural regulation of immunity has delineated anatomical connections, shared mediators and receptors for mediators with distinctive effects, and the immune functional consequences of altering relevant neural activities. Vasoactive intestinal peptide (VIP) and pituitary adenylyl cyclase-activating peptide (PACAP) are represented prominently in immune organs. They have potent novel effects on many aspects of immunity, are derived from and serve as autacoids in some sets of immune cells, and they participate in both physiological and pathological immune responses. The present phase of neuroimmune research has begun to elucidate the genetic determinants of expression and functions of neuromediators in immunity. Our evolving understanding of the novel mechanisms for adaptation and specificity in the VIP/PACAP neuroimmune network suggests the importance of immunoselective transcriptional control of expression of VIP/PACAP receptors in T cells, a dominant role for numerous cytokines, and the critical involvement of small subsets of VIP-/PACAP-responsive thymocytes and T cells.

Animals↗

PubMed2000

Structural and immunological characteristics of a 28-kilodalton cruzipain-like cysteine protease of Paragonimus westermani expressed in the definitive host stage.

A complete cDNA sequence encoding a 28-kDa cruzipain-like cysteine protease of adult Paragonimus westermani, termed Pw28CCP, was isolated from an adult cDNA library. The cDNA contained a single open reading frame of 975 bp encoding 325 amino acids, which exhibited the structural motif and domain organization characteristic of cysteine proteases of non-cathepsin Bs including a hydrophobic signal sequence, an ERFNIN motif, and essential cysteine residues as well as active sites in the mature catalytic region. Analysis of its phylogenetic position revealed that this novel enzyme belonged to the cruzipain-like cysteine proteases. The sequence of the first 13 amino acids predicted from the mature domain of Pw28CCP was in accord with that determined from the native 28-kDa enzyme purified from the adult worm. Expression of Pw28CCP was observed specifically in juvenile and adult worms, with a location in the intestinal epithelium, suggesting that this enzyme could be secreted and involved in nutrient uptake and immune modulation. The recombinant protein expressed in Escherichia coli was used to assess antigenicity by immunoblotting with sera from patients with active paragonimiasis and from those with other parasitic infections. The resulting sensitivity of 86.2% (56 of 65 samples) and specificity of 98% (147 of 150 samples) suggest its potential as an antigen for use in immunodiagnosis.

Amino Acid Sequence↗

PubMed2000

Persisting antibody reaction in paragonimiasis after praziquantel treatment is elicited mainly by egg antigens.

Antibody responses in serum and cerebrospinal fluid (CSF) samples from patients with active and chronic paragonimiasis and in sera from patients on whom follow-up studies were done after praziquantel treatment were analyzed using antigens of Paragonimus westermani prepared from eggs, metacercariae, juveniles of 4- and 7-week old, adult worms and recombinant protein of 28 kDa cruzipain-like cysteine protease (rPw28CCP). The patient sera/CSFs of active and chronic paragonimiasis revealed strong antibody reactions against the crude extracts of 4- and 7-week old juveniles as well as against those from egg and adult. rPw28CCP also showed specific reaction to the sera with active paragonimiasis. After the treatment, levels of specific antibodies in the sera gradually decreased to negative range in most patients. In some cases with persisting high antibody levels, however, the reactions at 27 kDa egg protein were sustained throughout the observation period of 34 months. The reactions at 35 and 32 kDa in adult extract and rPw28CCP disappeared rapidly after the treatment. Persistent antibody reactions even after successful treatment are provoked by continuous antigenic challenge from eggs which were not resolved by treatment.

Animals↗

PubMed2000

IgG antibody responses in early experimental sparganosis and IgG subclass responses in human sparganosis.

Antigenic components in the crude extracts of Spirometra mansoni plerocercoid were analyzed in early experimental infections and in IgG subclass observed in clinical sparganosis. By IgG immunoblot, sera obtained serially from experimental mice, fed 5 spargana each, were reacted with the crude extracts. Protein bands at 36-26 kDa and 103 kDa showed positive reactions since two weeks after infection. In a differential immunoblot, in which a monospecific antibody against sparganum chymase at 36 kDa was pre-treated, the reactions at 36-26 kDa disappeared, indicating that the sparganum chymase and its degradation products invoked IgG antibody reactions. When 69 patients sera of human sparganosis were examined for their IgG subclass responses, IgG4 levels showed the highest reaction which was followed by IgG1. The IgG4 antibody also reacted mainly with 36-31 kDa protease. These results indicate that 36 kDa chymase of S. mansoni plerocercoid is the main antigenic component inducing IgG antibody response in early stage of experimental sparganosis and for specific IgG subclass reactions in human sparganosis.

Animals↗

PubMed2000

The 10 kDa protein of Taenia solium metacestodes shows genus specific antigenicity.

Genus specific antigenicity of the 10 kDa protein in cyst fluid (CF) of Taenia solium metacestodes was demonstrated by comparative immunoblot analysis. When CFs from taeniid metacestodes of T. saginata, T. solium, T. taeniaeformis and T. crassiceps were probed with specific monoclonal antibody (mAb) raised against 150 kDa protein of T. solium metacestodes, specific antibody reactions were observed in 7 and 10 kDa proteins of T. solium and in 7/8 kDa of T. saginata, T. taeniaeformis and T. crassiceps. The mAb did not react with any protein in hydatid fluid of Echinococcus granulosus and E. multilocularis. This result revealed that the 10 kDa peptide of T. solium metacestodes and its equivalent proteins of different Taenia metacestodes are genus specific antigens that are shared among different Taenia species.

Animals↗

PubMed2000

Differential expression of the 27 kDa cathepsin L-like cysteine protease in developmental stages of Spirometra erinacei.

The 27 kDa cathepsin L-like cysteine protease of Spirometra erinacei plerocercoid is known to play an important function in tissue penetration, nutrient uptake and immune modulation in human sparganosis. In the present study, the expression of this enzyme was examined at different developmental stages of S. erinacei including immature egg, coracidium, plerocercoid in tadpole and rat, and adult. Proteolytic activity against carboxybenzoyl-phenylalanyl-arginyl-7-amino-4-methylcoumarin was detected in the extracts of coracidia and plerocercoid while no activity was observed in those of immature egg and adult. The specific activity in coracidial extracts was lower than that in the plerocercoid. Reverse transcription-polymerase chain reaction and Northern blot analysis demonstrated that the gene was expressed in the coracidium and plerocercoid but not in immature egg and adult. These results suggest that the 27 kDa cysteine protease is only expressed in the stages involving active migration of the parasite in the host tissue.

Animals↗

PubMed2000

[Factors affecting transformation of Agrobacterium tumefaciens and their application on cereals].

Agrobacterium tumefaciens mediated genetic transformation is the method most widely used in plant transformation. How to improve its transformation efficiency and extend its host range to include most cereals is what people concern about. There are many factors that influence the transformation efficiency, including the wounding response of plants, attachment of bacteria, induction of virulent gene, DNA repair and replication activity of plant cells, state of explant, etc. Recent research has proved that cerelas can be transformed effectively by A. tumefaciens under suitable conditions. This paper reviewed the recent progress in the two aspects.

Agrobacterium tumefaciens↗

PubMed2000

[Dynamics of respiration pathway in transgenic salt-tolerant wheat and its receptor under salt stress].

Using transgenic salt-tolerant wheat 89122 and its receptor Longchun 13 as test material, the dynamic changes of respiration pathway of wheat seedlings at different salt concentration were studied. The appearance of salt respiration was later in 89122 than in Longchun 13. The changes of Valt and rho Valt of both varieties had different patterns during salt stress process. Valt was suppressed by high salt levels, but could be induced by low salt levels in Longchun 13. The rho Valt and rho' Vcyt of two varieties were cooperatively regulated with each other to adapt to salt stress, and rho' Vcyt was the main electron transport pathway. The possible physiological roles of cyanide-resistant respiration were also discussed. It was suggested that the operation intensity of cyanide-resistant respiration could serve as a physiological index of plant salt-tolerance.

Oxygen Consumption↗

PubMed2000

[Dynamic changes of respiration pathway and active oxygen levels in subcultured tobacco callus].

During the growth and senescence of tobacco callus, the total respiration rate showed two peaks on the 11th and 19th day, respectively. The development and operation of alternative pathway increased gradually, reached the maximum between two respiration peaks, and then declined in the following days, but the cytochrome pathway was still as a main electron transport pathway consistently. Analysis on the levels of active oxygen species during the growth and senescence process in tobacco callus suggested that H2O2 and O2.- were involved in some way in the induction of the development and operation of the alternative pathway, but the increase of production rate of OH might suppress both the development and operation of the alternative pathway, which were enhanced by H2O2 and O2.- respectively. These results were further proved by the use of active oxygen scavengers. The possible participation of the alternative pathway enhanced by active oxygen in the initial senescence process was discussed.

Cells, Cultured↗