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At least 1,567 records · Page 87Linked to original sources
PubMed2001

Expression of RFG/ELE1alpha/ARA70 in normal and malignant prostatic epithelial cell cultures and lines: regulation by methylation and sex steroids.

RET fused gene (RFG)/ELE1alpha/androgen receptor-associated protein 70(ARA70) was first found to be involved in the activation of the RET proto-oncogene in thyroid neoplasm and has recently been shown to be a ligand-dependent transcriptional coregulator for androgen receptor (AR). The functionality of RFG/ELE1alpha/ARA70 remains controversial, and little is known about factors regulating its expression in the prostate. Of significant interest is whether this molecule is involved in prostate carcinogenesis. Using reverse transcriptase-polymerase chain reaction semiquantitation, we compared RFG/ELE1alpha/ARA70 mRNA levels in four prostate cancer cell lines (LNCaP, TSU-Pr1, DU-145, and PC-3) with those found in primary cultures of normal prostatic epithelial cells (PrECs). In addition, we examined the effects of androgen and antiandrogen, estrogen and antiestrogen, and a demethylating agent on RFG/ELE1alpha/ARA70 mRNA expression levels in AR- and AR+ PC-3 cells. Reduced levels of RFG/ELE1alpha/ARA70 message were observed in all four prostate cancer cell lines when compared with normal PrECs in primary cultures. RFG/ELE1alpha/ARA70 mRNA levels in PC-3 cells, which express both estrogen receptor subtypes, were upregulated by 17beta-estradiol and inhibited by the antiestrogen ICI-182780. In PC-3(AR+) cells, which were genetically engineered to express AR, exposure to androgen upregulated RFG/ELE1alpha/ARA70 mRNA expression, whereas treatment with 4-hydroxyflutamide lowered expression of this transcript. Furthermore, treatment of DU-145 cells, which did not express RFG/ELE1alpha/ARA70 transcripts, with a demethylating agent reactivated transcription of this gene. Polymerase chain reaction analyses of monochromosomal human-rodent hybrid panels localized a putative RFG/ELE1alpha/ARA70 isoform on human chromosome 5q31.1-31.2. In summary, we identified sex hormones and DNA hypermethylation as regulators of RFG/ELE1alpha/ARA70 expression in prostate cancer cells. In addition, we found reduced levels of RFG/ELE1alpha/ARA70 expression in prostate cancer cell lines when compared with expression levels in normal PrECs in culture. These findings suggest that RFG/ELE1alpha/ARA70 may be involved prostate carcinogenesis and that it may serve as a key mediator of estrogen-androgen synergism.

Androgens↗
PubMed2005

Repair of impaired myocardium by means of implantation of engineered autologous myoblast sheets.

OBJECTIVES: Autologous skeletal myoblast cell transplantation by means of the injection method is subject to the loss of intercellular communication, extracellular matrix, and cell numbers. We hypothesize that the implantation of skeletal myoblast cell sheets might be more advantageous in repairing the impaired heart by providing uniform and stable cell delivery with less cell loss and without disrupting the cell-cell microenvironment. METHODS: Left anterior descending coronary artery-ligated Lewis rat hearts (2 weeks, total n = 173) received 1 x 10(7) autologous skeletal myoblasts by means of cell transplantation either through myoblast injection or implantation of 2 monolayer-constructed myoblast sheets (5 x 10(6) cells per sheet) or through medium injection. Myoblast sheets were constructed with temperature-responsive, polymer-grafted cell-culture dishes, which release the confluent cells from the dish surface at less than 20 degrees C. RESULTS: Echocardiographic results indicated higher improvement of cardiac performance in the myoblast sheet group than among the other groups until 8 weeks after cell transplantation. Histologic comparison revealed greater cellularity and abundant widespread neocapillaries within the noticeable uniform thickened wall in myoblast sheet group hearts only. Fibrosis was substantially reduced with skeletal myoblast sheet implantation compared with skeletal myoblast cell injection. Obviously higher numbers of hematopoietic stem cells (c-kit, stem cell antigen 1, and CD34) were observed in the myoblast sheet group infarct heart region. Reverse transcription-polymerase chain reaction results showed expression of stromal-derived factor 1, hepatocyte growth factor, and vascular endothelial growth factor as follows: myoblast sheets > myoblast injection > control. CONCLUSIONS: Myoblast sheets repaired the impaired myocardium, reduced fibrosis, and prevented remodeling in association with recruitment of hematopoietic stem cells through the release of stromal-derived factor 1 and other growth factors. Our experiment indicates a therapy for patients with severe heart failure.

Animals↗
PubMed2006

[Effects of osteoblasts and inductor on proliferation and osteodifferentiation of marrow stromal stem cells].

OBJECTIVE: To find a new culture system to induce proliferation and osteodifferentiation of marrow stromal cells (MSCs) in vitro for bone tissue engineering. METHODS: There were four groups in this experiment to study effects of Passage 3 osteoblasts derived from the rat cranium and the osteogenic inductor (1 nmol/L dexamethasone, 10 mmol/L beta-glycero-phosphate, 50 microg/ml retinoic acid) on growth of MSCs isolated from the rat femur and the tibia. MSCs were cultured in the DMEM medium (the control group) and in the osteoinductive culture medium (the inductor group); furthermore, MSCs were co-cultured with the osteoblasts in the DMEM medium (the osteoblast group) and in the osteoinductive culture medium (the combined treatment group). The cells in the four groups were counted every 2 days for 8 days and alkaline phosphatase (ALP) activity of MSCs at 10 days of cultivation was measured. The MRNA expression of osteocalcin (OC) of MSCs at 2 weeks was assayed with the reverse transcript polymerase chain reaction (RT-PCR). RESULTS: There were more cells in the osteoblast group than in the control group (31.73 +/- 3.31 x 10(4) VS. 24.33 +/- 3.04 x 10(4), P < 0. 05), but there were fewer cells in the inductor group (16.23 +/- 2.44 x 10(4), P < 0.05). There was no significant difference in the cell number between the combined treatment group (21.54 +/- 2.29 x 10(4)) and the control group (P > 0.05). The ALP activity was higher in the combined treatment group (2.01 +/- 0.56 U) than in the control group (1.27 +/- 0.43 U), in the inductor group (1.27 +/- 0.43 U), and in the osteoblast group (0.77 +/- 0.19 U). The osteocalcin mRNA was expressed in the three treatment groups but was not expressed in the control group. The significantly higher level of the osteocalcin mRNA was expressed in the inductor group (0.783 +/- 0.094) and in the combined treatment group (0.814 +/- 0.071) than in the osteoblast group (0.302 +/- 0.026) (P < 0.05). CONCLUSION: The combined use of the osteoblast and the inductor can induce marrow stromal cells. Their combined use does not affect the normal proliferation but can obviously promote the osteodifferentiation of marrow stromal cells. This combined use can become a new culture system of the seed cells for bone tissue engineering.

Animals↗
PubMed2002

Chemical genetic blockade of transformation reveals dependence on aberrant oncogenic signaling.

BACKGROUND: Our understanding of protein kinase inhibition in the treatment of cancer is clearly limited by the lack of inhibitors that selectively block a single kinase implicated in neoplastic transformation. One approach to developing specific inhibitors is to engineer in protein kinases silent mutations that allow selective inhibition while retaining kinase activity. Because it is implicated in a large number of malignancies, EGFR provides an attractive target for such selective kinase inhibition. RESULTS: We generated an inhibitor-sensitized allele of the transforming receptor tyrosine kinase v-erbB. Transformation of immortalized rodent fibroblasts by sensitized versions of v-erbB (v-erbB-as1) was blocked by 1-napthyl PP1 (NaPP1), a cell-permeable ATP-competitive inhibitor. NaPP1 also reversed morphological transformation by v-erbB-as1. Signaling through MAP kinase and PI(3) kinase was initially blocked by inhibitor treatment and then recovered to levels comparable to those in nontransformed cells. Surprisingly, NaPP1-treated v-erbB-as1 cells failed to re-enter the cell cycle, showed decreased levels of D- and A-type cyclins, and showed increased levels of p27. To extend this result, we showed that NaPP1 treatment of v-Src-as1 cells also led to cell cycle arrest. Arrested cells could be rescued with a conditional allele of Raf or by transduction of a constitutive allele of cyclin D1. CONCLUSIONS: These data suggest that mammalian cells can become dependent on aberrant oncogenic signaling; this dependency renders them incapable of returning to a normal, proliferative phenotype.

3T3 Cells↗
PubMed2001

Molecular cloning and functional identification of (+)-delta-cadinene-8-hydroxylase, a cytochrome P450 mono-oxygenase (CYP706B1) of cotton sesquiterpene biosynthesis.

In cotton, gossypol and related sesquiterpene aldehydes are present in the glands of aerial tissues and in epidermal cells of roots. A cytochrome P450 was found to be expressed in aerial tissues of glanded cotton cultivars, but not or at an extremely low level in the aerial tissues of a glandless cultivar. Its cDNA was then isolated from Gossypium arboreum L. After expression in Saccharomyces cerevisiae, the P450 was found to catalyse the hydroxylation of (+)-delta-cadinene, forming 8-hydroxy-(+)-delta-cadinene. This P450 mono-oxygenase has been classified as CYP706B1, and is the first member of the CYP706 family for which a function has been determined. Sesquiterpene aldehydes and CYP706B1 transcripts were detected in roots of both the glanded and glandless cultivars and in aerial tissues of the glanded cultivar. In suspension cultured cells of G. arboreum, elicitors prepared from the phytopathogenic fungus Verticillium dahliae caused a dramatic induction of CYP706B1 expression. The expression pattern of CYP706B1 and the position at which it hydroxylates (+)-delta-cadinene suggest that it catalyses an early step in gossypol biosynthesis. Southern blotting revealed a single copy of CYP706B1 in the genome of G. arboreum. CYP706B1 holds good potential for manipulation of gossypol levels in cottonseed via genetic engineering.

Chromatography, High Pressure Liquid↗
PubMed2005

Glyco-engineering of moss lacking plant-specific sugar residues.

The commercial production of complex pharmaceutical proteins from human origin in plants is currently limited through differences in protein N-glycosylation pattern between plants and humans. On the one hand, plant-specific alpha(1,3)-fucose and beta(1,2)-xylose residues were shown to bear strong immunogenic potential. On the other hand, terminal beta(1,4)-galactose, a sugar common on N-glycans of pharmaceutically relevant proteins, e.g., antibodies, is missing in plant N-glycan structures. For safe and flexible production of pharmaceutical proteins, the humanisation of plant protein N-glycosylation is essential. Here, we present an approach that combines avoidance of plant-specific and introduction of human glycan structures. Transgenic strains of the moss Physcomitrella patens were created in which the alpha(1,3)-fucosyltransferase and beta(1,2)-xylosyltransferase genes were knocked out by targeted insertion of the human beta(1,4)-galactosyltransferase coding sequence in both of the plant genes (knockin). The transgenics lacked alpha(1,3)-fucose and beta(1,2)-xylose residues, whereas beta(1,4)-galactose residues appeared on protein N-glycans. Despite these significant biochemical changes, the plants did not differ from wild type with regard to overall morphology under standard cultivation conditions. Furthermore, the glyco-engineered plants secreted a transiently expressed recombinant human protein, the vascular endothelial growth factor, in the same concentration as unmodified moss, indicating that the performed changes in glycosylation did not impair the secretory pathway of the moss. The combined knockout/knockin approach presented here, leads to a new generation of engineered moss and towards the safe and flexible production of correctly processed pharmaceutical proteins with humanised N-glycosylation profiles.

Base Sequence↗
PubMed1985

The present and future of cardiac assist devices.

This article describes the status of development of an implantable electrically powered ventricular assist device designed for a minimum of a 2-year operation in patients with advanced heart failure. While these devices are envisioned for chronic support of the failing circulation, air-driven blood pumps have been used to provide life support to patients with acute ventricular dysfunction produced by a reversible myocardial injury of unknown origin. The physical and hemodynamic characteristics of the mechanical circulatory support devices are detailed. Clinical indications and results are provided on patients treated with temporary ventricular assist devices. Long-term follow-up of some patients has demonstrated sustained improved cardiac function for up to 5 years after treatment. Reperfusion injury and postischemic myocardial depression are discussed as two possible etiologies of acute ventricular dysfunction. In the summer of 1984, investigators began a collaborative program to test the engineering reliability of implantable devices as well as their performance in animals. This 3-year Device Readiness Program had a goal of demonstrating an 80% reliability with a confidence interval of 70%. In the future, the implantable device will be evaluated clinically in selected patients to investigate its ability to support circulatory functions and the results of host-device interactions. These devices have potential both as experimental tools in studies of heart and vascular disease and in the treatment of patients with intractable heart failure.

Adult↗
PubMed2001

Factors influencing blood flow patterns in the human right coronary artery.

Evidence suggests that atherogenesis is linked to local hemodynamic factors such as wall shear stress. We investigated the velocity and wall shear stress patterns within a human right coronary artery (RCA), an important site of atherosclerotic lesion development. Emphasis was placed on evaluating the effect of flow waveform and inlet flow velocity profile on the hemodynamics in the proximal, medial, and distal arterial regions. Using the finite-element method, velocity and wall shear stress patterns in a rigid, anatomically realistic model of a human RCA were computed. Steady flow simulations (ReD=500) were performed with three different inlet velocity profiles; pulsatile flow simulations utilized two different flow waveforms (both with Womersley parameter=1.82, mean ReD=233), as well as two of the three inlet profiles. Velocity profiles showed Dean-like secondary flow features that were remarkably sensitive to the local curvature of the RCA model. Particularly noteworthy was the "rotation" of these Dean-like profiles, which produced large local variations in wall shear stress along the sidewalls of the RCA model. Changes in the inlet velocity profiles did not produce significant changes in the arterial velocity and wall shear stress patterns. Pulsatile flow simulations exhibited remarkably similar cycle-average wall shear stress distributions regardless of waveform and inlet velocity profile. The oscillatory shear index was very small and was attributed to flow reversal in the waveform, rather than separation. Cumulatively, these results illustrate that geometric effects (particularly local three-dimensional curvature) dominate RCA hemodynamics, implying that studies attempting to link hemodynamics with atherogenesis should replicate the patient-specific RCA geometry.

Arteriosclerosis↗
PubMed1995

Purification and partial sequencing of the major mitogen for human uterine smooth muscle-like cells in leiomyoma extracts.

We purified the major mitogen for human smooth muscle-like cells in leiomyoma extracts by sequential liquid chromatography on (a) carboxymethyl-Sepharose, (b) heparin-Sepharose columns, (c) cartridges of C18 silica, and (d) linear gradient reverse-phase high performance liquid chromatography. The mitogenic activity of the leiomyoma extract throughout purification was tested by tritiated thymidine incorporation and DNA content in NIH/3T3 fibroblasts and KW human smooth muscle-like cells. Purification of the leiomyoma-derived growth factor (LDGF) for KW smooth muscle-like cells confirmed that its partial NH2-terminal amino acid (aa) sequence (1-20 aa) was identical to 113-132 aa of the human cysteine-rich protein (hCRP). A synthetic peptide which was engineered based on the purified aa sequence, stimulated the proliferation and growth of KW cells. An oligonucleotide probe constructed by the cDNA of the hcrp gene that encodes this aa sequence depicted the expression of 1.9-kb LDGF mRNA in leiomyomas and myometrium. The expression of the LDGF mRNA was three to sixfold higher in leiomyomas compared with adjacent myometrium of women harboring leiomyomas by in situ hybridization analysis. These data suggest that LDGF may participate in the pathophysiology of uterine leiomyomas.

3T3 Cells↗
PubMed1998

Myeloid progenitor cell proliferation and mobilization effects of BB10010, a genetically engineered variant of human macrophage inflammatory protein-1alpha, in a phase I clinical trial in patients with relapsed/refractory breast cancer.

Macrophage Inflammatory Protein (MIP)-1alpha is myelosuppressive in vitro and in vivo for hematopoietic stem and immature subsets of myeloid progenitor cells, demonstrates some myeloprotective effects in mice treated with Ara-C and hydroxyurea, and has stem/progenitor cell mobilizing activity in mice. Based on these observations, BB10010, a genetic variant of MIP-1alpha, was assessed for effects on marrow and blood myeloid progenitor cells in patients with relapsed/refractory breast cancer. MIP-1alpha readily polymerizes, whereas BB10010 has a reduced tendency to form large polymers at physiological pH and ionic strength and retains biological activity. Patients were injected with 5, 10, 30 or 100 microg/kg BB10010 s.c. daily for 3 days. BB10010 significantly reduced the cycling status of marrow myeloid progenitors from pretreatment levels of 39-58% to 0 - 11% one day after the third and last injection of BB10010. This was associated with significant decreases in frequency of marrow progenitors (number of colonies formed per number of cells plated) and percent biopsied marrow CD34+ cells. The suppressive effects were reversible in patients and the rapidity of this reversal demonstrated in mouse studies. BB10010 had no effect on nucleated cellularity or on the proliferation of nucleated cells as assessed in marrow biopsies from the patients. These latter effects may in part reflect the noted decreased apoptosis of nucleated cells by BB10010. BB10010 also demonstrated significant but modest myeloid progenitor cell mobilizing capacity. Blood progenitors were in a slow or non-cycling state prior to treatment and this did not change after administration of BB10010. The above effects of BB10010 were similar at the four different dosage levels assessed. These results demonstrate in humans the suppressive and mobilizing effects of MIP-1alpha and BB10010 previously noted in vivo in mice.

Adult↗
PubMedDate not supplied

Life forms protectable as subjects of US patents--microbes to animals (perhaps).

Scientists, businessmen, universities, and industries with fundamental or peripheral interests in technology as applied to life processes will be keenly interested in recent US Patent Office decisions. These decisions indicate that new higher life forms, animal or plant, are proper subjects of patents if they are not naturally occurring (and are not human, in the case of animals). In contrast to plants and other organisms, genetically modified animals have had no mode of protection as intellectual property except possibly as trade secrets or utility patents. The Ex parte Allen decision, reached by the Patent Office Board of Appeals and Interferences, directly addressed the issue of animal patentability in view of the broad reading of 35 U.S.C. section 101 by the US Supreme Court in the Chakrabarty decision. The subject invention concerned polyploid oysters. Claims directed toward polyploid oysters produced by a particular process were rejected under 35 U.S.C. section 103 and section 101. The Board, reversing the 35 U.S.C. section 101-based rejection in view of the Chakrabarty decision, indicated that the claimed polyploid oysters were non-naturally occurring manufactures or compositions of matter within the confines of patentable subject matter under 35 U.S.C. section 101. A similar decision affecting the patentable status of plants or segments thereof had previously been reached by the Patent and Trademark Office in the case of Ex parte Hibberd, 227 U.S.P.Q. 443 (Bd. Pat. App. 1985). The Hibberd utility patent application concerned "genetically engineered" maize which had high levels of the tryptophan.

Animals↗
PubMed1999

Applications of a peptide ligand for streptavidin: the Strep-tag.

The Strep-tag constitutes a nine amino acid-peptide that binds specifically to streptavidin and occupies the same pocket where biotin is normally complexed. Since the Strep-tag participates in a reversible interaction it can be applied for the efficient purification of corresponding fusion proteins on affinity columns with immobilized streptavidin. Elution of the bound recombinant protein can be effected under mild buffer conditions by competition with biotin or a suitable derivative. In addition, Strep-tag fusion proteins can be easily detected in immunochemical assays, like Western blots or ELISAs, by means of commercially available streptavidin-enzyme conjugates. The Strep-tag/streptavidin system has been systematically optimized over the past years, including the engineering of streptavidin itself. Structural insight into the molecular mimicry between the peptide and biotin was furthermore gained from X-ray crystallographic analysis. As a result the system provides a reliable and versatile tool in recombinant protein chemistry. Exemplary applications of the Strep-tag are discussed in this review.

Affinity Labels↗
PubMed2004

Glycosidation of chlorophenols by Lemna minor.

Metabolic fate of xenobiotics in plant tissues has an important role in the ultimate fate of these compounds in natural and engineered systems. Chlorophenols are an important class of xenobiotics used in a variety of biocides and have been shown to be resistant to microbial degradation. Three chlorophenyl glycosides were extracted from tissues of Lemna minor exposed to 2,4-dichlorophenol (DCP). The products were identified as 2,4-dichlorophenyl-beta-D-glucopyranoside (DCPG), 2,4-dichlorophenyl-beta-D-(6-O-malonyl)-glucopyranoside (DCPMG) and 2,4-dichlorophenyl-beta-D-glucopyranosyl-(6 --> 1)-beta-D-apiofuranoside (DCPAG). Identification was based on reverse phase retention (C18), electrospray mass spectra collected in negative and positive mode (ESI-NEG and ESI-POS, respectively), and nuclear magnetic resonance (NMR) spectra comparisons to reference materials synthesized in the laboratory. Liquid chromatography-mass spectrometry (LC-MS) analysis of plants exposed to 2,4,5-trichlorophenol (TCP) formed analogous compounds: 2,4,5-trichlorophenyl-beta-D-glucopyranoside (TCPG), 2,4,5-trichlorophenyl-beta-D-(6-O-malonyl)-glucopyranoside (TCPMG) and 2,4,5-trichlorophenyl-beta-D-glucopyranosyl-(6 --> 1)-beta-D-apiofuranoside (TCPAG). Enzyme catalyzed hydrolysis with beta-glucosidase was ineffective in releasing the beta-glucosides with chemical modifications at C6. Presence of these glucoconjugates confirmed that L. minor was capable of xenobiotic uptake and transformation. Identification of these products suggested that chlorophenols were incorporated into vacuoles and cell walls of L. minor.

Araceae↗
PubMed1989

Life forms protectable as subjects of U.S. patents -- microbes to animals (perhaps).

Scientists, businessmen, universities and industries with fundamental or peripheral interests in technology as applied to life processes will be keenly interested in recent U.S. Patent Office decisions. These decisions indicate that new higher life forms, animal or plant, are proper subjects of patents if they are not naturally occurring (and are not human in the case of animals). In contrast to plants and other organisms, genetically modified animals have had no mode of protection as intellectual property except possibly as a trade secret or utility patent. The Ex parte Allen decision, reached by the Patent Office Board of Appeals and Interferences, directly addressed the issue of animal patentability in view of the broad reading of 35 U.S.C. section 101 by the U.S. Supreme Court in the Chakrabarty decision. The subject invention concerned polyploid oysters. Claims directed toward polyploid oysters produced by a particular process were rejected under 35 U.S.C. section 103 and section 101. The Board, reversing the 35 U.S.C. section 101 - based rejection in view of the Chakrabarty decision, indicated that the claimed polyploid oysters were non-naturally occurring manufactures or compositions of matter within the confines of patentable subject matter under 35 U.S.C. section 101. A similar decision affecting the patentable status of plants or segments thereof had previously been reached by the Patent and Trademark Office in the case of Ex parte Hibberd, 227 U.S.P.Q. 443 (Bd. Pat. App. 1985). The Hibberd utility patent application concerned "genetically engineered" maize which had high levels of the tryptophan.

Animals↗
PubMed1997

Live fish vaccines: history and perspectives.

In the development of live vaccines against enzootic fish viral diseases, the conventional approaches, although somewhat successful, failed finally to deliver efficient, safe, and tagged strains for vaccine application. The genetically-engineered vaccine approach also gave similarly disappointing results. Faced with these realities during our work with VHS, we turned our research effort towards understanding the molecular basis of virulence and antigenicity of the virus. Using sequence analysis of neutralization-escape mutants, we identified several amino acid positions on the glycoprotein which seemed to be involved in the pathological process. The attenuated phenotype was consistently associated with simultaneous mutations at two distant regions, 125-140 and 430-433 of the glycoprotein. We also demonstrated that reversion to virulence was accompanied by the loss of the concurrent mutations, which confirmed their involvement in virulence. The importance of these two regions of the glycoprotein was confirmed by the finding that laboratory or naturally attenuated variants had mutations within these regions. Using the same methodology, we selected mutants from an attenuated temperature resistant variant (tr25), which had previously been developed in our laboratory. Virulence, antigenicity and protective activity of the further attenuated mutants were evaluated in fish of different size by intramuscular (i.m.) or water bath administration. Strains having an additional mutation at position 139 were completely non-virulent for fish of 1000-1400 degree-days (dxd) by bath. These mutants retained their immunogenicity and had a thermo-resistant, an antigenic, and five genetic markers. Thus, they will constitute ideal candidates for live vaccine development, once their protective activity and containment have been confirmed in field trials.

Amino Acid Sequence↗
PubMed2004

Bone repair in the twenty-first century: biology, chemistry or engineering?

Increases in reconstructive orthopaedic surgery, such as total hip replacement and spinal fusion, resulting from advances in surgical practice and the ageing population, have lead to a demand for bone graft that far exceeds supply. Consequently, a number of synthetic bone-graft substitutes (BGSs) have been developed with mixed success and surgical acceptance. Skeletal tissue regeneration requires the interaction of three basic elements: cells, growth factors (GFs) and a permissive scaffold. This can be achieved by pre-loading a synthetic scaffold with GFs or pre-expanded cells; however, a 'simpler' approach is to design intrinsic 'osteoinductivity' into your BGS, i.e. the capability to recruit and stimulate the patient's own GFs and stem cells. Through investigation of the mechanisms controlling bone repair in BGSs, linking interactions between the local chemical and physical environment, scientists are currently developing osteoinductive materials that can stimulate bone regeneration through control of the scaffold chemistry and structure. Moreover, this body of research is providing the foundations for future generations of BGSs and bone-repair therapies and may ultimately contribute towards improving the quality of life through maintenance of the skeleton and reversal of disease states, as opposed to the mending of broken bones that we currently practice. Will we be able to grow our own bones in a bioreactor for use as autologous graft materials in the future? Could surgery be limited to accidental trauma cases, with greater restoration of function through biochemical or gene therapies? The technology and research probes necessary to this task are currently being developed with the advent of nanotechnology, genomics and proteomics: are we about to embark on a chemical revolution in medicine? This paper aims to discuss some of the current thinking on the mechanisms behind bioactivity and biocompatibility in bone and how a fuller understanding of the interactions between cells and the materials used today could bring about completely new approaches for the treatment of bone fracture and disease tomorrow.

Animals↗
PubMed2002

Engineering water to act as an active site acid catalyst in a soluble fumarate reductase.

The ability of an arginine residue to function as the active site acid catalyst in the fumarate reductase family of enzymes is now well-established. Recently, a dual role for the arginine during fumarate reduction has been proposed [Mowat, C. G., Moysey, R., Miles, C. S., Leys, D., Doherty, M. K., Taylor, P., Walkinshaw, M. D., Reid, G. A., and Chapman, S. K. (2001) Biochemistry 40, 12292-12298] in which it acts both as a Lewis acid in transition-state stabilization and as a Brønsted acid in proton delivery. This proposal has led to the prediction that, if appropriately positioned, a water molecule would be capable of functioning as the active site Brønsted acid. In this paper, we describe the construction and kinetic and crystallographic analysis of the Q363F single mutant and Q363F/R402A double mutant forms of flavocytochrome c(3), the soluble fumarate reductase from Shewanella frigidimarina. Although replacement of the active site acid, Arg402, with alanine has been shown to eliminate fumarate reductase activity, this phenomenon is partially reversed by the additional substitution of Gln363 with phenylalanine. This Gln --> Phe substitution in the inactive R402A mutant enzyme was designed to "push" a water molecule close enough to the substrate C3 atom to allow it to act as a Brønsted acid. The 2.0 A resolution crystal structure of the Q363F/R402A mutant enzyme does indeed reveal the introduction of a water molecule at the correct position in the active site to allow it to act as the catalytic proton donor. The 1.8 A resolution crystal structure of the Q363F mutant enzyme shows a water molecule similarly positioned, which can account for its measured fumarate reductase activity. However, in this mutant enzyme Michaelis complex formation is impaired due to significant and unpredicted structural changes at the active site.

Arginine↗
PubMed2001

BION system for distributed neural prosthetic interfaces.

We have developed the first in a planned series of neural prosthetic interfaces that allow multichannel systems to be assembled from single-channel micromodules called BIONs (BIOnic Neurons). Multiple BION implants can be injected directly into the sites requiring stimulating or sensing channels, where they receive power and digital commands by inductive coupling to an externally generated radio-frequency magnetic field. This article describes some of the novel technology required to achieve the required microminiaturization, hermeticity, power efficiency and clinical performance. The BION1 implants are now being used to electrically exercise paralyzed and weak muscles to prevent or reverse disuse atrophy. This modular, wireless approach to interfacing with the peripheral nervous system should facilitate the development of progressively more complex systems required to address a growing range of clinical applications, leading ultimately to synthesizing complete voluntary functions such as reach and grasp.

Animals↗