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Biomedical subjects

C Ma

Publications and source records attributed to C Ma.

At least 19 recordsLinked to original sources
PubMed2002

Variation of nanomechanical properties of bone by gene mutation in the zebrafish.

Significant variations of nanomechanical properties and fracture morphology between gene-mutated liliput(dtc232) (lil/lil) zebrafish skeletal bone and wild-type bone have been observed. Nanoindentation measurement disclosed that lil/lil bone has 36% lower nanohardness and 32% lower elastic modulus. The standard deviations of hardness and elastic modulus of lil/lil bone were both much higher than those of wild-type bone. SEM morphology of fracture surfaces further revealed that in bones after gene mutation, formative microcracks make the performance reduction and the increasing of brittleness. What is more, the plywood-like structure of the normal bone does not exist in the lil/lil bone.

Animals↗
PubMed2002

Pattern recognition proteins in Manduca sexta plasma.

Recognition of nonself is the first step in mounting immune responses. In the innate immune systems of both vertebrates and arthropods, such recognition, termed pattern recognition, is mediated by a group of proteins, known as pattern recognition proteins or receptors. Different pattern recognition proteins recognize and bind to molecules (molecular patterns) present on the surface of microorganisms but absent from animals. These molecular patterns include microbial cell wall components such as bacterial lipopolysaccharide, lipoteichoic acid and peptidoglycan, and fungal beta-1,3-glucans. Binding of pattern recognition proteins to these molecular patterns triggers responses such as phagocytosis, nodule formation, encapsulation, activation of proteinase cascades, and synthesis of antimicrobial peptides. In this article, we describe four classes of pattern recognition proteins, hemolin, peptidoglycan recognition protein, beta-1,3-glucan recognition proteins, and immulectins (C-type lectins) involved in immune responses of the tobacco hornworm, Manduca sexta.

Amino Acid Sequence↗
PubMed2002

Effects of GnRH analogues, 'add-back' steroid therapy, antiestrogen and antiprogestins on leiomyoma and myometrial smooth muscle cell growth and transforming growth factor-beta expression.

The objective of this study was to elucidate the biological significance of GnRH and antiprogestins and antiestrogen in leiomyoma and their interactions with ovarian steroid 'add-back' therapy. Leiomyoma and myometrial smooth muscle cells (LSMC and MSMC) were isolated and exposed to GnRH agonist (leuprolide acetate, LA), 17beta-estradiol (E2), medroxyprogesterone acetate (MPA), GnRH antagonist (Antide), estrogen antagonist, ICI182780 (Fulvestrant) and progesterone antagonists RU486 (Mifepristone) and ZK98299 (Onapristone) and combinations thereof. The rate of DNA synthesis, cell proliferation and transforming growth factor-beta (TGF-beta) expression were then determined. In both cell types, we found that in a dose-dependent manner, LA inhibited, whereas E2, MPA and the combination of E2 + MPA stimulated, the rate of DNA synthesis in these cells. Antide reversed the inhibitory effect of LA, while LA partly inhibited the stimulatory effect of the steroids. In addition, RU486, ICI182780 and ZK98299 at 0.1 micro mol/l or higher doses inhibited the rate of DNA synthesis and partly reversed the effects of E2 and/or MPA. We also found that LSMC expressed elevated levels of TGF-beta1 compared with MSMC. In both cell types, the effects of LA, E2, MPA, RU, ZK and ICI and combinations thereof on TGF-beta1 production were reflective of their effects on DNA synthesis. In line with this, TGF-beta1 was found to stimulate DNA synthesis and the E2-, TGF-beta1- or E2 + TGF-beta1-induced DNA synthesis was found to be inhibited by TGF-beta1 neutralizing antibodies and/or LA. In conclusion, the results provide further evidence that GnRH agonist- and RU486-induced leiomyoma regression is mediated in part through an interactive mechanism that results in altered cell growth and suppression of TGF-beta production.

Estradiol↗
PubMed2001

Bryostatin-1 specifically inhibits in vitro IgE synthesis.

Bryostatin-1, a macrocyclic lactone, is an antineoplastic agent that potently activates protein kinase C. Bryostatin-1 (Bryo) had an immunomodulatory effect on murine B cells in that it specifically inhibited IgE production. IgE levels were inhibited in a B cell dose-response curve, whereas IgM and IgG1 were induced by Bryo treatment. Taken together, ELISPOT and surface Ig staining data suggested that Bryo inhibition occurred at the level of class switching. RT-PCR and real time PCR data showed that this inhibition was achieved at an early step in switch recombination, namely, the appearance of Iepsilon germline transcripts. Although Bryo caused a delay in the proliferative response of IL-4/CD40 ligand trimer-stimulated B cells, CFSE studies revealed that the Bryo-mediated inhibition of class switching to IgE occurred independently of the number of division cycles. Notably, Bryo showed the same specific IgE inhibition in human B cells. This study provides evidence for a unique mechanism regulating IgE production possibly downstream of PKC by specifically modulating Iepsilon germline transcription.

Animals↗
PubMed2001

Efficient asymmetric synthesis of biologically important tryptophan analogues via a palladium-mediated heteroannulation reaction.

A novel and concise synthesis of optically active tryptophan derivatives was developed via a palladium-catalyzed heteroannulation reaction of substituted o-iodoanilines with an internal alkyne. The required internal alkyne 14a or 25 was prepared in greater than 96% de via alkylation of the Schöllkopf chiral auxiliary 19 employing diphenyl phosphate as the leaving group. The Schöllkopf chiral auxiliary was chosen here for the preparation of L-tryptophans would be available from D-valine while the D-isomers required for natural product total synthesis would originate from the inexpensive L-valine (300-g scale). Applications of the palladium-catalyzed heteroannulation reaction were extended to the first asymmetric synthesis of L-isotryptophan 38 and L-benz[f]tryptophan 39. More importantly, the optically pure 6-methoxy-D-tryptophan 62 was prepared by this protocol on a large scale (>300 g). This should permit entry into many ring-A oxygenated indole alkaloids when coupled with the asymmetric Pictet-Spengler reaction. In addition, an improved total synthesis of tryprostatin A (9a) was accomplished in 43% overall yield employing this palladium-mediated process.

Alkylation↗
PubMed2001

Matrix immobilization enhances the tissue repair activity of growth factor gene therapy vectors.

Although growth factor proteins display potent tissue repair activities, difficulty in sustaining localized therapeutic concentrations limits their therapeutic activity. We reasoned that enhanced histogenesis might be achieved by combining growth factor genes with biocompatible matrices capable of immobilizing vectors at delivery sites. When delivered to subcutaneously implanted sponges, a platelet-derived growth factor B-encoding adenovirus (AdPDGF-B) formulated in a collagen matrix enhanced granulation tissue deposition 3- to 4-fold (p < or = 0.0002), whereas vectors encoding fibroblast growth factor 2 or vascular endothelial growth factor promoted primarily angiogenic responses. By day 8 posttreatment of ischemic excisional wounds, collagen-formulated AdPDGF-B enhanced granulation tissue and epithelial areas up to 13- and 6-fold (p < 0.009), respectively, and wound closure up to 2-fold (p < 0.05). At longer times, complete healing without excessive scar formation was achieved. Collagen matrices were shown to retain both vector and transgene products within delivery sites, enabling the transduction and stimulation of infiltrating repair cells. Quantitative PCR and RT-PCR demonstrated both vector DNA and transgene mRNA within wound beds as late as 28 days posttreatment. By contrast, aqueous formulations allowed vector seepage from application sites, leading to PDGF-induced hyperplasia in surrounding tissues but not wound beds. Finally, repeated applications of PDGF-BB protein were required for neotissue induction approaching equivalence to a single application of collagen-immobilized AdPDGF-B, confirming the utility of this gene transfer approach. Overall, these studies demonstrate that immobilizing matrices enable the controlled delivery and activity of tissue promoting genes for the effective regeneration of injured tissues.

Adenoviridae↗
PubMed2001

[The antagonistic effects of adrenomedullin on biological events governed by transforming growth factor beta in HK-2 cell line].

OBJECTIVE: To investigate the influence of adrenomedullin (AM) on the biological events governed by transforming growth factorbeta (TGF-beta) in human tubular epithelial cell line (HK-2). METHODS: Cell proliferation was determined by (3)H-TdR incorporation; ELISA method was used to detect the level of secreted fibronectin (FN); total collagen synthesis and secretion were reflected by (3)H-proline incorporation and the radioactivity of (3)H-hydroproline in the culture medium; the expression of FN mRNA, collagen IV mRNA and TIMP-1mRNA was determined by RT-PCR; plasma AM was measured by radioimmunoassay. RESULTS: (1) AM had no effect on cell growth inhibition of TGF-beta(1) (P > 0.05); (2) AM dose-dependently inhibited collagen synthesis and secretion stimulated by TGF-beta(1). As compared with those in TGF-beta group, collagen synthesis and secretion in AM (10(-8) mol/L group were inhibited by 8% (P > 0.05) and 30% (P < 0.05), respectively; and the collagen synthesis and secretion in AM (10(-7) mol/L) group were inhibited by 57% (P < 0.05) and 64% (P < 0.01), respectively in AM (10(-7) mol/L) group. Similarly, AM (10(-8) mol/L) inhibited the FN secretion (20 ng/microliter +/- 5 ng/microliter) stimulated by TGF-beta(1) (28 ng/microliter +/- 6 ng/microliter) (P < 0.05). RT-PCR showed that AM significantly down-regulated the expression of collagen IV, FN and TIMP-1 mRNA stimulated by TGF-beta(1). (3) The plasma AM in patients with mild tubulointerstitial lesion was 1. 2 times higher than that in normal controls. the plasma AM in patients with severe tubulointerstitial lesion was 2.2 times higher than that in normal controls. The plasma AM in patients with severe tubulointerstitial lesion was 50% higher than that in patients with mild tubulointerstitial lesion (P < 0.01). CONCLUSIONS: AM antagonizes the biological action of TGF-beta(1) on extracellular matrix accumulation; plasma AM increases in glomerulonephritis patients and correlates with the degree of tubulointerstitial lesion.

Adolescent↗
PubMed2001

Regulation of Xenopus oocyte meiosis arrest by G protein betagamma subunits.

BACKGROUND: Progesterone induces the resumption of meiosis (maturation) in Xenopus oocytes through a nongenomic mechanism involving inhibition of an oocyte adenylyl cyclase and reduction of intracellular cAMP. However, progesterone action in Xenopus oocytes is not blocked by pertussis toxin, and this finding indicates that the inhibition of the oocyte adenylyl cyclase is not mediated by the alpha subunits of classical G(i)-type G proteins. RESULTS: To investigate the possibility that G protein betagamma subunits, rather than alpha subunits, play a key role in regulating oocyte maturation, we have employed two structurally distinct G protein betagamma scavengers (G(t)alpha and betaARK-C(CAAX)) to sequester free Gbetagamma dimers. We demonstrated that the injection of mRNA encoding either of these Gbetagamma scavengers induced oocyte maturation. The Gbetagamma scavengers bound an endogenous, membrane-associated Gbeta subunit, indistinguishable from Xenopus Gbeta1 derived from mRNA injection. The injection of Xenopus Gbeta1 mRNA, together with bovine Ggamma2 mRNA, elevated oocyte cAMP levels and inhibited progesterone-induced oocyte maturation. CONCLUSION: An endogenous G protein betagamma dimer, likely including Xenopus Gbeta1, is responsible for maintaining oocyte meiosis arrest. Resumption of meiosis is induced by Gbetagamma scavengers in vitro or, naturally, by progesterone via a mechanism that suppresses the release of Gbetagamma.

Animals↗
PubMed2001

Production of zebrafish germ-line chimeras from embryo cell cultures.

Although the zebrafish possesses many characteristics that make it a valuable model for genetic studies of vertebrate development, one deficiency of this model system is the absence of methods for cell-mediated gene transfer and targeted gene inactivation. In mice, embryonic stem cell cultures are routinely used for gene transfer and provide the advantage of in vitro selection for rare events such as homologous recombination and targeted mutation. Transgenic animals possessing a mutated copy of the targeted gene are generated when the selected cells contribute to the germ line of a chimeric embryo. Although zebrafish embryo cell cultures that exhibit characteristics of embryonic stem cells have been described, successful contribution of the cells to the germ-cell lineage of a host embryo has not been reported. In this study, we demonstrate that short-term zebrafish embryo cell cultures maintained in the presence of cells from a rainbow trout spleen cell line (RTS34st) are able to produce germ-line chimeras when introduced into a host embryo. Messenger RNA encoding the primordial germ-cell marker, vasa, was present for more than 30 days in embryo cells cocultured with RTS34st cells or their conditioned medium and disappeared by 5 days in the absence of the spleen cells. The RTS34st cells also inhibited melanocyte and neuronal cell differentiation in the embryo cell cultures. These results suggest that the RTS34st splenic-stromal cell line will be a valuable tool in the development of a cell-based gene transfer approach to targeted gene inactivation in zebrafish.

Animals↗
PubMed2001

Molecular definition of the germinal centre stage of B-cell differentiation.

Genomic-scale gene expression analysis provides views of biological processes as a whole that are difficult to obtain using traditional single-gene experimental approaches. In the case of differentiating systems, gene expression profiting can define a stage of differentiation by the characteristic expression of hundreds of genes. Using specialized DNA microarrays termed 'Lymphochips', gene expression during mature B-cell differentiation has been defined. Germinal centre B cells represent a stage of differentiation that can be defined by a gene expression signature that is not shared by other highly proliferative B-cell populations such as mitogenically activated peripheral blood B cells. The germinal centre gene expression signature is maintained to a significant degree in lymphoma cell lines derived from this stage of differentiation, demonstrating that this gene expression programme does not require ongoing interactions with other germinal centre cell types. Analysis of representative cDNA libraries prepared from resting and activated peripheral blood B cells, germinal centre centroblasts, centrocytes and tonsillar memory B cells has confirmed and extended the results of DNA microarray gene expression analysis.

B-Lymphocytes↗
PubMed2001

The expression and action of granulocyte macrophage-colony stimulating factor and its interaction with TGF-beta in endometrial carcinoma.

OBJECTIVE: Previous studies have demonstrated that normal human endometrium expresses granulocyte macrophage-colony stimulating factor (GM-CSF) and GM-CSF receptors. Because GM-CSF is administer to cancer patients following chemotherapy, GM-CSF may directly or through interaction with ovarian steroids and other cytokines alter the behavior of endometrial cancer. The aim of this study was to determine the expression of GM-CSF and receptors in endometrial carcinoma and its direct effect and interaction with transforming growth factor beta (TGF-beta) on Ishikawa cells, a human endometrial carcinoma cell line. METHODS: GM-CSF, GM-CSF receptors, TGF-beta1, and TGF-beta type II receptor expression were evaluated using quantitative reverse transcription polymerase chain reaction (Q-RT-PCR). The effect of GM-CSF on DNA synthesis, cell proliferation, expression of GM-CSF, TGF-beta1, and TGF-beta receptor, and their regulation by ovarian steroids was determined by the rate of [(3)H]thymidine incorporation, MTT assay, Q-RT-PCR, and ELISA, respectively. RESULTS: Endometrial carcinomas express significantly higher GM-CSF and GM-CSF alpha and beta receptor mRNA compared with normal postmenopausal endometrium. GM-CSF at various doses had no significant effect on the rate of [(3)H]thymidine incorporation or proliferation of Ishikawa cells, whereas TGF-beta1 inhibited [(3)H]thymidine incorporation. GM-CSF and TGF-beta1 regulate their own expression and the expression of TGF-beta type II receptor, which were both upregulated by 17beta-estradiol and medroxyprogesterone acetate treatment and reversed following cotreatment with their respective receptor antagonists. CONCLUSION: Endometrial carcinoma expresses an elevated level of GM-CSF and GM-CSF receptors. GM-CSF is not a mitogen for the endometrial cancer cell line; however, either alone or through interaction with TGF-beta1, it regulates its own expression and the expression of TGF-beta1 and TGF-beta type II receptor which inhabits endometrial cancer cells. This interaction may represent a regulatory feedback mechanism that could serve to suppress endometrial carcinoma growth.

Antineoplastic Agents, Hormonal↗
PubMed2001

Structural studies of the HIV-1 accessory protein Vpu in langmuir monolayers: synchrotron X-ray reflectivity.

Vpu is an 81 amino acid integral membrane protein encoded by the HIV-1 genome with a N-terminal hydrophobic domain and a C-terminal hydrophilic domain. It enhances the release of virus from the infected cell and triggers degradation of the virus receptor CD4. Langmuir monolayers of mixtures of Vpu and the phospholipid 1,2-dilignoceroyl-sn-glycero-3-phosphocholine (DLgPC) at the water-air interface were studied by synchrotron radiation-based x-ray reflectivity over a range of mole ratios at constant surface pressure and for several surface pressures at a maximal mole ratio of Vpu/DLgPC. Analysis of the x-ray reflectivity data by both slab model-refinement and model-independent box-refinement methods firmly establish the monolayer electron density profiles. The electron density profiles as a function of increasing Vpu/DLgPC mole ratio at a constant, relatively high surface pressure indicated that the amphipathic helices of the cytoplasmic domain lie on the surface of the phospholipid headgroups and the hydrophobic transmembrane helix is oriented approximately normal to the plane of monolayer within the phospholipid hydrocarbon chain layer. At maximal Vpu/DLgPC mole ratio, the tilt of the transmembrane helix with respect to the monolayer normal decreases with increasing surface pressure and the conformation of the cytoplasmic domain varies substantially with surface pressure.

Amino Acid Sequence↗
PubMed2001

Differential expression of integrin alpha v and beta 3 in serosal tissue of human intraperitoneal organs and adhesion.

OBJECTIVE: To assess the expression of integrin alpha v and beta 3 in the serosal tissue of intraperitoneal organs and adhesions in persons with and without adhesions. DESIGN: Prospective study. SETTING: Academic research centers. PATIENT(S): Fifty-seven patients undergoing abdominal or pelvic surgery. MAIN OUTCOME MEASURE(S): Integrin alpha v and beta 3 messenger RNA (mRNA) expression was evaluated by quantitative reverse transcription polymerase chain reaction. RESULT(S): The serosal tissue of the parietal peritoneum, uterus, fallopian tubes, ovary, and the large and small bowel, as well as peritoneal adhesions, skin, fascia, subcutaneous tissue, and omentum, expresses integrin alpha v and beta 3 mRNA. The level of alpha v and beta 3 mRNA expression varied among these tissues; expression of the former substance was highest in uterine serosa and lowest in the skin and small bowel, and expression of the latter substance was highest in the fallopian tubes and skin and lowest in the uterine serosa. Parietal peritoneum and adhesions express equal levels of integrin alpha v; however, integrin beta 3 expression was >100-fold lower in adhesions than in peritoneum. The level of integrin beta 3 expression in omentum, small and large bowels, and subcutaneous tissue was 100-fold to 10,000-fold lower than in other tissues. CONCLUSION(S): Serosal tissue of peritoneal organs and adhesions express variable levels of integrin alpha v and beta 3 mRNA. On the basis of such variation and the knowledge that tissue injury alters local integrin expression, integrins may play a key role in adhesion development, particularly in tissue with higher integrin expression.

Adult↗