Our models focus on specific areas, enabling us to build science. Nevertheless, their specialisat... more Our models focus on specific areas, enabling us to build science. Nevertheless, their specialisation leads to incompleteness. This incompleteness, once acknowledged, can serve as a heuristic, stimulating the generation of new hypotheses, models and discoveries. The utility of our models also lies in the conscious and rational use of their incompletenes
A critical missing step in our therapeutic strategies is the normalization of the healing process... more A critical missing step in our therapeutic strategies is the normalization of the healing process through the formation of its endpoint, the functional scar. The scarring process is a necessary contributor to brain healing. The scar is not a consequence but a factor in the healing process. The formation of a mature glial scar takes several weeks to reach completion and requires the absence of exacerbating injury.[5] The spread of invasive cancer cells and therapy‑induced tissue damages are such exacerbating injuries. A largely overlooked point is that although invasive brain tumors elicit reactive gliosis, they are not surrounded by a well‑defined astrocyte or fibrotic scar. The question arises as to why we have neglected to consider the resolution of the scarring process into a mature scar as a therapeutic imperative.
La regulation de l'expression du gene ngf a ete etudiee dans la lignee de fibroblastes nurins... more La regulation de l'expression du gene ngf a ete etudiee dans la lignee de fibroblastes nurins l-929 a l'aide d'une sonde de cdna permettant de quantifier le rna messager ngf. L'abondance du ngf transcript est dependante des conditions de culture: serum, hormones thyroidiennes et acide retinoique stimulent le taux de transcription du gene ngf alors que la dexamethasone la diminue. Le gene ngf du poulet et le dna complementaire de la chaine lourde des neurofilaments ont ete clones et sequences. Les sondes moleculaires rendent possibles l'etude de la coexpression au cours de l'embryogenese des genes codant pour des facteurs trophiques (ngf) et des marqueurs neuronaux (neurofilament)
L-929 cells secrete a neurotrophic factor which is immunologically related to the beta NGF presen... more L-929 cells secrete a neurotrophic factor which is immunologically related to the beta NGF present in the male Mouse submaxillary gland. In order to determine whether L-929 cells also synthesize the alpha and gamma subunits which are associated with the beta NGF in the gland, immunoprecipitations were performed with appropriate antisera. Our results indicate the absence of alpha and gamma subunits in the extracellular medium or in the cell extracts and suggest that the synthesis and secretion of the beta NGF by the L cells does not require these two proteins.
We have analyzed the growth factor content and properties In secretory vesicles of modlfled sympa... more We have analyzed the growth factor content and properties In secretory vesicles of modlfled sympathetic neurons, adrenal medtdlary chromaffin cells, which contain a cocktail of several neurotrophk acthrltles. NEUROTROFMNS: Using different assay systems, we were able to demonstrate the absence of nerve growth factor from chromnffln cells. Other neurotrophlns alao seem not to be present, because nodoaa gnrtglionlc neurons are not maintalned by veslcie proteins. FIBRO~LAST (3ROWTti FACTORS: Two bFGF-llke proteins (lmmunologkally crossreacttve, comparable acthrity) of 18 and 46 kD are present In ve$icJes and may serve as a phy-slologk2al factors In malntainlng the spinal cord neurons Innetvatlng chromaffin cells.
Gliomas are one of the most deadly primary cancers. These primary brain tumors almost invariably ... more Gliomas are one of the most deadly primary cancers. These primary brain tumors almost invariably relapse despite multimodal treatments combining surgery, radiotherapy, and chemotherapy. Surgery and chemo/radiotherapy can significantly increase the survival rate. [1] However, glioma still remains a deadly disease. Promising results from early Phase II clinical trials are rarely confirmed in Phase III trials, and innovative targeted therapies have failed to make major breakthroughs to date. This situation again emphasizes the importance of stratifying the patients included in Phase III clinical trials on the basis of biological or molecular markers in relation to the therapeutic target of the trial. The remarkable degree of plasticity of glioma cells is of major therapeutic concern as it contributes to treatment resistance. However, the differentiation/dedifferentiation potential of cancer cells can be also viewed as a therapeutic opportunity. For instance, inhibiting cancer stem cell or more generally cancer cell renewal by promoting their differentiation toward a postmitotic phenotype would limit cancer progression and tumor growth. This is the basis for
Peritumoral brain invasion is the main target to cure glioblastoma. Chemoradiotherapy and targete... more Peritumoral brain invasion is the main target to cure glioblastoma. Chemoradiotherapy and targeted therapies fail to combat peritumoral relapse. Brain inaccessibility and tumor heterogeneity explain this failure, combined with overlooking the peritumor microenvironment. Reduce graphene oxide (rGO) provides a unique opportunity to modulate the local brain microenvironment. Multimodal graphene impacts are reported on glioblastoma cells in vitro but fail when translated in vivo because of low diffusion. This issue is solved by developing a new rGO formulation involving ultramixing during the functionalization with polyethyleneimine (PEI) leading to the formation of highly water‐stable rGO‐PEI. Wide mice brain diffusion and biocompatibility are demonstrated. Using an invasive GL261 model, an anti‐invasive effect is observed. A major unexpected modification of the peritumoral area is also observed with the neutralization of gliosis. In vitro, mechanistic investigations are performed using primary astrocytes and cytokine array. The result suggests that direct contact of rGO‐PEIUT neutralizes astrogliosis, decreasing several proinflammatory cytokines that would explain a bystander tumor anti‐invasive effect. rGO also significantly downregulates several proinvasive/protumoral cytokines at the tumor cell level. The results open the way to a new microenvironment anti‐invasive nanotherapy using a new graphene nanomaterial that is optimized for in vivo brain delivery.
The effect of the neurotrophic factor nerve growth factor (NGF) on the expression of the β-amyloi... more The effect of the neurotrophic factor nerve growth factor (NGF) on the expression of the β-amyloid gene has been studied in the clonal nerve cell line PC 12. The neuronal differentiation of PC 12 cells in the presence of NGF was accompanied by a shift in the ratio of s-amyloid precursor protein (APP) transcripts. In particular there was reduced expression of the transcript coding for the longest precursor form (APP770) and a concomitant increase in the shortest (APP695) transcript following NGF treatment. These observations may have important implications in relation to β-amyloid processing in Alzheimer’s disease.
Vitamin D is a secosteroid that can be formed by the cleavage of 7-dehydrocholesterol by UV light... more Vitamin D is a secosteroid that can be formed by the cleavage of 7-dehydrocholesterol by UV light. The biologically active metabolite of vitamin D is generated following two hydroxylation steps, in position 25 in the liver and position 1a in the kidney. 1a,25-dihydroxyvitamin D3 (1,25-D3) binds to an intracellular receptor belonging to the nuclear hormone-receptor superfamily, which includes receptors for classical steroids, tri-iodothyronine (T3) or retinoic acid (RA). The vitamin D receptor (VDR) can form active heterodimers, for instance with the RXR receptor, which binds 9-cis RA. Binding of VDR to responsive elements present in regulatory regions of target genes results in transcriptional effects (for review, see Christakos et al. 1996; Haussler et al. 1997). In addition, 1,25-D3 exerts membrane-mediated effects such as the induction of rapid, transient changes of intracellular free calcium, which are observed in numerous cell types. 1,25-D3 is mainly known for its calcemic and phosphatemic action in intestine or bone. However, it is also active in the immune system, in which monocytes or activated lymphocytes express the VDR. 1,25-D3 promotes the differentiation of monocytes into macrophages and increases their phagocytic potential (Prowedini et al. 1986; Rook et al. 1986; Kreutz and Andreseen 1990). Conversely, the hormone inhibits the production of TNF-a and IL- 12 (Zarrabeitia et al. 1992; Lemire et al. 1994), an interleukin that favours the differentiation of CD4-positive lymphocytes towards the Thl subtype. Likewise, the hormone down-regulates various cell surface proteins, such as the major histocompatibility complex (MHC) class II antigen, CD4, or the B7-2 costimulatory molecule (Rigby et al. 1990; Spittler et al. 1997; Clavreul et al. 1998). 1,25-D3 exerts an anti-proliferative action on Tor B lymphocytes and inhibits more specifically the production of IFN-y and IL-2, which are released by the Th1 lymphocytes (Reichel et al. 1987; Rigby et al. 1987). Hence, the hormone exerts various immunosuppressive effects that are evidenced in vivo by the fact that prophylactic 1,25-D3 treatments, performed at pharmacological doses, prevent the outcome of autoimmune diseases such as insulinitis or lupus erythematosus in genetically susceptible mice (Lemire et al. 1992; Mathieu et al. 1992). Likewise, 1,25-D3, when applied during the immunization phase, protects susceptible rodents against experimental allergic encephalomyelitis (Lemire and Archer 1990).
L-929 cells derive from a mouse connective tissue (Earle 1943). They secrete a neurotrophic facto... more L-929 cells derive from a mouse connective tissue (Earle 1943). They secrete a neurotrophic factor which is immunologically and biochemically similar to the β-NGF found in mouse submaxillary glands (Oger et al. 1974; Brachet and Dicou 1984). Hybridizations with a β-NGF cDNA probe (Scott et al. 1983) have recently shown that L cells contain a β-NGF transcript identical in size to that produced by the submaxillary gland, and that the β-NGF locus of the genomic DNA is not rearranged, as evidenced by cleavage with some restriction enzymes (Wion et al. 1985). L cells, therefore, constitute a valuable model system suited for the study of the gene expression of the factor. The present work deals with a preliminary characterization of extracellular effector molecules which influence this expression. Extracellular concentrations of β-NGF were correlated with intracellular levels of the β-NGF mRNA in cells cultured in the presence or absence of serum, or exposed to testosterone, T3 or T4, which are known to enhance the β-NGF levels in the mouse submaxillary gland (Levi Montalcini and Angeletti 1968; Aloe and Levi Montalcini 1980).
Biochemical and Biophysical Research Communications, 2000
The necessary amplification step in bacteria of any plasmid currently used in DNA immunization or... more The necessary amplification step in bacteria of any plasmid currently used in DNA immunization or gene therapy introduces modification in the nucleotide sequence of plasmid DNA used in gene transfer. These changes affect the adenine and the internal cytosine in respectively all of the GATC and CC(A/T)GG sequences. These modifications which introduce 6-methyladenine and 5-methylcytosine in plasmidic DNA are the consequence of the existence of the bacterial modification systems Dam and Dcm. In eucaryotes, the presence of 5-methylcytosine at dinucleotides-CG-is involved in silencing gene expression, but the possible consequences of the presence of the bacterial G m ATC and C m C(A/T)GG sequences in the plasmids used in gene transfer experiments are presently unknown. Since the possibility exists to obtain plasmid DNA lacking this specific bacterial pattern of methylation by using (dam ؊ , dcm ؊) bacteria we performed experiments to compare in vitro and in vivo gene transfer efficiency of a pCMV-luc reporter plasmid amplified either in the JM109 (dam ؉ , dcm ؉) or JM110 (dam ؊ , dcm ؊) bacteria. Data obtained demonstrated that the presence of 6-methyladenine in GATC sequences and 5-methylcytosine in the second C of CC(A/T)GG motifs does not reduce the levels of luciferase activity detected following in vitro or in vivo gene transfer. On the contrary, gene transfer with a pCMV-luc amplified in JM109 (dam ؉ , dcm ؉) bacteria gives greater amounts of luciferase than the same transfection performed with a plasmid amplified in the mutated JM110 (dam ؊ , dcm ؊) counterpart. Therefore, these data do not suggest that the use of (dam ؊ , dcm ؊) bacteria to amplify plasmid DNA may increase gene transfer efficiency. However, the persistence of the use of (dam ؉ , dcm ؉) bacteria in order to amplify plasmid DNA raises the question of the possible biological consequences of the introduction of the bacterial G m ATC and C m C(A/T)GG sequences in eukaryotic cells or organisms.
Gliomas are one of the most deadly primary cancers. These primary brain tumors almost invariably ... more Gliomas are one of the most deadly primary cancers. These primary brain tumors almost invariably relapse despite multimodal treatments combining surgery, radiotherapy, and chemotherapy. Surgery and chemo/radiotherapy can significantly increase the survival rate. [1] However, glioma still remains a deadly disease. Promising results from early Phase II clinical trials are rarely confirmed in Phase III trials, and innovative targeted therapies have failed to make major breakthroughs to date. This situation again emphasizes the importance of stratifying the patients included in Phase III clinical trials on the basis of biological or molecular markers in relation to the therapeutic target of the trial. The remarkable degree of plasticity of glioma cells is of major therapeutic concern as it contributes to treatment resistance. However, the differentiation/dedifferentiation potential of cancer cells can be also viewed as a therapeutic opportunity. For instance, inhibiting cancer stem cell or more generally cancer cell renewal by promoting their differentiation toward a postmitotic phenotype would limit cancer progression and tumor growth. This is the basis for
A largely overlooked point is that although invasive brain tumors elicit reactive gliosis, they a... more A largely overlooked point is that although invasive brain tumors elicit reactive gliosis, they are not surrounded by a well-defined astrocyte or fibrotic scar. In the words of Hippocrates, “Medicine consists of adding and subtracting, subtracting what is in excess, adding what is deficient.” In glioblastoma, the readily observable excess to subtract is the tumor mass. This may have led us to focus our therapeutic efforts on subtractive treatments such as tumor resection and killing cancer cells. To observe a deficiency like a scar defect is less straightforward. A deficiency is defined in reference to a control. Neither scar is observable in patients, nor in the normal nontrauma tissues used as controls in our studies. Scarring is an emergent function of tissues; a cell does not scar, but tissue does. Therefore, the observation of a mature scar is also not common in experimental cell culture studies. A critical missing step in our therapeutic strategies is the normalization of the healing process through the formation of its endpoint, the functional scar. It is necessary to resolve this issue to make palliative therapies curative.
A largely overlooked point is that although invasive
brain tumors elicit reactive gliosis, they a... more A largely overlooked point is that although invasive brain tumors elicit reactive gliosis, they are not surrounded by a well-defined astrocyte or fibrotic scar. In the words of Hippocrates, “Medicine consists of adding and subtracting, subtracting what is in excess, adding what is deficient.” In glioblastoma, the readily observable excess to subtract is the tumor mass. This may have led us to focus our therapeutic efforts on subtractive treatments such as tumor resection and killing cancer cells. To observe a deficiency like a scar defect is less straightforward. A deficiency is defined in reference to a control. Neither scar is observable in patients, nor in the normal nontrauma tissues used as controls in our studies. Scarring is an emergent function of tissues; a cell does not scar, but tissue does. Therefore, the observation of a mature scar is also not common in experimental cell culture studies. A critical missing step in our therapeutic strategies is the normalization of the healing process through the formation of its endpoint, the functional scar. It is necessary to resolve this issue to make palliative therapies curative.
Our models focus on specific areas, enabling us to build science. Nevertheless, their specialisat... more Our models focus on specific areas, enabling us to build science. Nevertheless, their specialisation leads to incompleteness. This incompleteness, once acknowledged, can serve as a heuristic, stimulating the generation of new hypotheses, models and discoveries. The utility of our models also lies in the conscious and rational use of their incompletenes
A critical missing step in our therapeutic strategies is the normalization of the healing process... more A critical missing step in our therapeutic strategies is the normalization of the healing process through the formation of its endpoint, the functional scar. The scarring process is a necessary contributor to brain healing. The scar is not a consequence but a factor in the healing process. The formation of a mature glial scar takes several weeks to reach completion and requires the absence of exacerbating injury.[5] The spread of invasive cancer cells and therapy‑induced tissue damages are such exacerbating injuries. A largely overlooked point is that although invasive brain tumors elicit reactive gliosis, they are not surrounded by a well‑defined astrocyte or fibrotic scar. The question arises as to why we have neglected to consider the resolution of the scarring process into a mature scar as a therapeutic imperative.
La regulation de l'expression du gene ngf a ete etudiee dans la lignee de fibroblastes nurins... more La regulation de l'expression du gene ngf a ete etudiee dans la lignee de fibroblastes nurins l-929 a l'aide d'une sonde de cdna permettant de quantifier le rna messager ngf. L'abondance du ngf transcript est dependante des conditions de culture: serum, hormones thyroidiennes et acide retinoique stimulent le taux de transcription du gene ngf alors que la dexamethasone la diminue. Le gene ngf du poulet et le dna complementaire de la chaine lourde des neurofilaments ont ete clones et sequences. Les sondes moleculaires rendent possibles l'etude de la coexpression au cours de l'embryogenese des genes codant pour des facteurs trophiques (ngf) et des marqueurs neuronaux (neurofilament)
L-929 cells secrete a neurotrophic factor which is immunologically related to the beta NGF presen... more L-929 cells secrete a neurotrophic factor which is immunologically related to the beta NGF present in the male Mouse submaxillary gland. In order to determine whether L-929 cells also synthesize the alpha and gamma subunits which are associated with the beta NGF in the gland, immunoprecipitations were performed with appropriate antisera. Our results indicate the absence of alpha and gamma subunits in the extracellular medium or in the cell extracts and suggest that the synthesis and secretion of the beta NGF by the L cells does not require these two proteins.
We have analyzed the growth factor content and properties In secretory vesicles of modlfled sympa... more We have analyzed the growth factor content and properties In secretory vesicles of modlfled sympathetic neurons, adrenal medtdlary chromaffin cells, which contain a cocktail of several neurotrophk acthrltles. NEUROTROFMNS: Using different assay systems, we were able to demonstrate the absence of nerve growth factor from chromnffln cells. Other neurotrophlns alao seem not to be present, because nodoaa gnrtglionlc neurons are not maintalned by veslcie proteins. FIBRO~LAST (3ROWTti FACTORS: Two bFGF-llke proteins (lmmunologkally crossreacttve, comparable acthrity) of 18 and 46 kD are present In ve$icJes and may serve as a phy-slologk2al factors In malntainlng the spinal cord neurons Innetvatlng chromaffin cells.
Gliomas are one of the most deadly primary cancers. These primary brain tumors almost invariably ... more Gliomas are one of the most deadly primary cancers. These primary brain tumors almost invariably relapse despite multimodal treatments combining surgery, radiotherapy, and chemotherapy. Surgery and chemo/radiotherapy can significantly increase the survival rate. [1] However, glioma still remains a deadly disease. Promising results from early Phase II clinical trials are rarely confirmed in Phase III trials, and innovative targeted therapies have failed to make major breakthroughs to date. This situation again emphasizes the importance of stratifying the patients included in Phase III clinical trials on the basis of biological or molecular markers in relation to the therapeutic target of the trial. The remarkable degree of plasticity of glioma cells is of major therapeutic concern as it contributes to treatment resistance. However, the differentiation/dedifferentiation potential of cancer cells can be also viewed as a therapeutic opportunity. For instance, inhibiting cancer stem cell or more generally cancer cell renewal by promoting their differentiation toward a postmitotic phenotype would limit cancer progression and tumor growth. This is the basis for
Peritumoral brain invasion is the main target to cure glioblastoma. Chemoradiotherapy and targete... more Peritumoral brain invasion is the main target to cure glioblastoma. Chemoradiotherapy and targeted therapies fail to combat peritumoral relapse. Brain inaccessibility and tumor heterogeneity explain this failure, combined with overlooking the peritumor microenvironment. Reduce graphene oxide (rGO) provides a unique opportunity to modulate the local brain microenvironment. Multimodal graphene impacts are reported on glioblastoma cells in vitro but fail when translated in vivo because of low diffusion. This issue is solved by developing a new rGO formulation involving ultramixing during the functionalization with polyethyleneimine (PEI) leading to the formation of highly water‐stable rGO‐PEI. Wide mice brain diffusion and biocompatibility are demonstrated. Using an invasive GL261 model, an anti‐invasive effect is observed. A major unexpected modification of the peritumoral area is also observed with the neutralization of gliosis. In vitro, mechanistic investigations are performed using primary astrocytes and cytokine array. The result suggests that direct contact of rGO‐PEIUT neutralizes astrogliosis, decreasing several proinflammatory cytokines that would explain a bystander tumor anti‐invasive effect. rGO also significantly downregulates several proinvasive/protumoral cytokines at the tumor cell level. The results open the way to a new microenvironment anti‐invasive nanotherapy using a new graphene nanomaterial that is optimized for in vivo brain delivery.
The effect of the neurotrophic factor nerve growth factor (NGF) on the expression of the β-amyloi... more The effect of the neurotrophic factor nerve growth factor (NGF) on the expression of the β-amyloid gene has been studied in the clonal nerve cell line PC 12. The neuronal differentiation of PC 12 cells in the presence of NGF was accompanied by a shift in the ratio of s-amyloid precursor protein (APP) transcripts. In particular there was reduced expression of the transcript coding for the longest precursor form (APP770) and a concomitant increase in the shortest (APP695) transcript following NGF treatment. These observations may have important implications in relation to β-amyloid processing in Alzheimer’s disease.
Vitamin D is a secosteroid that can be formed by the cleavage of 7-dehydrocholesterol by UV light... more Vitamin D is a secosteroid that can be formed by the cleavage of 7-dehydrocholesterol by UV light. The biologically active metabolite of vitamin D is generated following two hydroxylation steps, in position 25 in the liver and position 1a in the kidney. 1a,25-dihydroxyvitamin D3 (1,25-D3) binds to an intracellular receptor belonging to the nuclear hormone-receptor superfamily, which includes receptors for classical steroids, tri-iodothyronine (T3) or retinoic acid (RA). The vitamin D receptor (VDR) can form active heterodimers, for instance with the RXR receptor, which binds 9-cis RA. Binding of VDR to responsive elements present in regulatory regions of target genes results in transcriptional effects (for review, see Christakos et al. 1996; Haussler et al. 1997). In addition, 1,25-D3 exerts membrane-mediated effects such as the induction of rapid, transient changes of intracellular free calcium, which are observed in numerous cell types. 1,25-D3 is mainly known for its calcemic and phosphatemic action in intestine or bone. However, it is also active in the immune system, in which monocytes or activated lymphocytes express the VDR. 1,25-D3 promotes the differentiation of monocytes into macrophages and increases their phagocytic potential (Prowedini et al. 1986; Rook et al. 1986; Kreutz and Andreseen 1990). Conversely, the hormone inhibits the production of TNF-a and IL- 12 (Zarrabeitia et al. 1992; Lemire et al. 1994), an interleukin that favours the differentiation of CD4-positive lymphocytes towards the Thl subtype. Likewise, the hormone down-regulates various cell surface proteins, such as the major histocompatibility complex (MHC) class II antigen, CD4, or the B7-2 costimulatory molecule (Rigby et al. 1990; Spittler et al. 1997; Clavreul et al. 1998). 1,25-D3 exerts an anti-proliferative action on Tor B lymphocytes and inhibits more specifically the production of IFN-y and IL-2, which are released by the Th1 lymphocytes (Reichel et al. 1987; Rigby et al. 1987). Hence, the hormone exerts various immunosuppressive effects that are evidenced in vivo by the fact that prophylactic 1,25-D3 treatments, performed at pharmacological doses, prevent the outcome of autoimmune diseases such as insulinitis or lupus erythematosus in genetically susceptible mice (Lemire et al. 1992; Mathieu et al. 1992). Likewise, 1,25-D3, when applied during the immunization phase, protects susceptible rodents against experimental allergic encephalomyelitis (Lemire and Archer 1990).
L-929 cells derive from a mouse connective tissue (Earle 1943). They secrete a neurotrophic facto... more L-929 cells derive from a mouse connective tissue (Earle 1943). They secrete a neurotrophic factor which is immunologically and biochemically similar to the β-NGF found in mouse submaxillary glands (Oger et al. 1974; Brachet and Dicou 1984). Hybridizations with a β-NGF cDNA probe (Scott et al. 1983) have recently shown that L cells contain a β-NGF transcript identical in size to that produced by the submaxillary gland, and that the β-NGF locus of the genomic DNA is not rearranged, as evidenced by cleavage with some restriction enzymes (Wion et al. 1985). L cells, therefore, constitute a valuable model system suited for the study of the gene expression of the factor. The present work deals with a preliminary characterization of extracellular effector molecules which influence this expression. Extracellular concentrations of β-NGF were correlated with intracellular levels of the β-NGF mRNA in cells cultured in the presence or absence of serum, or exposed to testosterone, T3 or T4, which are known to enhance the β-NGF levels in the mouse submaxillary gland (Levi Montalcini and Angeletti 1968; Aloe and Levi Montalcini 1980).
Biochemical and Biophysical Research Communications, 2000
The necessary amplification step in bacteria of any plasmid currently used in DNA immunization or... more The necessary amplification step in bacteria of any plasmid currently used in DNA immunization or gene therapy introduces modification in the nucleotide sequence of plasmid DNA used in gene transfer. These changes affect the adenine and the internal cytosine in respectively all of the GATC and CC(A/T)GG sequences. These modifications which introduce 6-methyladenine and 5-methylcytosine in plasmidic DNA are the consequence of the existence of the bacterial modification systems Dam and Dcm. In eucaryotes, the presence of 5-methylcytosine at dinucleotides-CG-is involved in silencing gene expression, but the possible consequences of the presence of the bacterial G m ATC and C m C(A/T)GG sequences in the plasmids used in gene transfer experiments are presently unknown. Since the possibility exists to obtain plasmid DNA lacking this specific bacterial pattern of methylation by using (dam ؊ , dcm ؊) bacteria we performed experiments to compare in vitro and in vivo gene transfer efficiency of a pCMV-luc reporter plasmid amplified either in the JM109 (dam ؉ , dcm ؉) or JM110 (dam ؊ , dcm ؊) bacteria. Data obtained demonstrated that the presence of 6-methyladenine in GATC sequences and 5-methylcytosine in the second C of CC(A/T)GG motifs does not reduce the levels of luciferase activity detected following in vitro or in vivo gene transfer. On the contrary, gene transfer with a pCMV-luc amplified in JM109 (dam ؉ , dcm ؉) bacteria gives greater amounts of luciferase than the same transfection performed with a plasmid amplified in the mutated JM110 (dam ؊ , dcm ؊) counterpart. Therefore, these data do not suggest that the use of (dam ؊ , dcm ؊) bacteria to amplify plasmid DNA may increase gene transfer efficiency. However, the persistence of the use of (dam ؉ , dcm ؉) bacteria in order to amplify plasmid DNA raises the question of the possible biological consequences of the introduction of the bacterial G m ATC and C m C(A/T)GG sequences in eukaryotic cells or organisms.
Gliomas are one of the most deadly primary cancers. These primary brain tumors almost invariably ... more Gliomas are one of the most deadly primary cancers. These primary brain tumors almost invariably relapse despite multimodal treatments combining surgery, radiotherapy, and chemotherapy. Surgery and chemo/radiotherapy can significantly increase the survival rate. [1] However, glioma still remains a deadly disease. Promising results from early Phase II clinical trials are rarely confirmed in Phase III trials, and innovative targeted therapies have failed to make major breakthroughs to date. This situation again emphasizes the importance of stratifying the patients included in Phase III clinical trials on the basis of biological or molecular markers in relation to the therapeutic target of the trial. The remarkable degree of plasticity of glioma cells is of major therapeutic concern as it contributes to treatment resistance. However, the differentiation/dedifferentiation potential of cancer cells can be also viewed as a therapeutic opportunity. For instance, inhibiting cancer stem cell or more generally cancer cell renewal by promoting their differentiation toward a postmitotic phenotype would limit cancer progression and tumor growth. This is the basis for
A largely overlooked point is that although invasive brain tumors elicit reactive gliosis, they a... more A largely overlooked point is that although invasive brain tumors elicit reactive gliosis, they are not surrounded by a well-defined astrocyte or fibrotic scar. In the words of Hippocrates, “Medicine consists of adding and subtracting, subtracting what is in excess, adding what is deficient.” In glioblastoma, the readily observable excess to subtract is the tumor mass. This may have led us to focus our therapeutic efforts on subtractive treatments such as tumor resection and killing cancer cells. To observe a deficiency like a scar defect is less straightforward. A deficiency is defined in reference to a control. Neither scar is observable in patients, nor in the normal nontrauma tissues used as controls in our studies. Scarring is an emergent function of tissues; a cell does not scar, but tissue does. Therefore, the observation of a mature scar is also not common in experimental cell culture studies. A critical missing step in our therapeutic strategies is the normalization of the healing process through the formation of its endpoint, the functional scar. It is necessary to resolve this issue to make palliative therapies curative.
A largely overlooked point is that although invasive
brain tumors elicit reactive gliosis, they a... more A largely overlooked point is that although invasive brain tumors elicit reactive gliosis, they are not surrounded by a well-defined astrocyte or fibrotic scar. In the words of Hippocrates, “Medicine consists of adding and subtracting, subtracting what is in excess, adding what is deficient.” In glioblastoma, the readily observable excess to subtract is the tumor mass. This may have led us to focus our therapeutic efforts on subtractive treatments such as tumor resection and killing cancer cells. To observe a deficiency like a scar defect is less straightforward. A deficiency is defined in reference to a control. Neither scar is observable in patients, nor in the normal nontrauma tissues used as controls in our studies. Scarring is an emergent function of tissues; a cell does not scar, but tissue does. Therefore, the observation of a mature scar is also not common in experimental cell culture studies. A critical missing step in our therapeutic strategies is the normalization of the healing process through the formation of its endpoint, the functional scar. It is necessary to resolve this issue to make palliative therapies curative.
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scar.
The scarring process is a necessary contributor to brain healing. The scar is not a consequence but a factor in the healing process. The formation of a mature glial scar takes several weeks to reach completion and requires the absence of exacerbating injury.[5] The spread of invasive cancer cells and therapy‑induced tissue damages are such exacerbating injuries. A largely overlooked point is that although invasive brain tumors elicit reactive gliosis, they are not surrounded by a well‑defined astrocyte or fibrotic scar. The question arises as to why we have neglected to consider the resolution of the scarring process into a mature scar as a therapeutic imperative.
brain tumors elicit reactive gliosis, they are not surrounded by
a well-defined astrocyte or fibrotic scar.
In the words of Hippocrates, “Medicine consists of adding
and subtracting, subtracting what is in excess, adding what
is deficient.” In glioblastoma, the readily observable excess
to subtract is the tumor mass. This may have led us to focus
our therapeutic efforts on subtractive treatments such as tumor
resection and killing cancer cells. To observe a deficiency
like a scar defect is less straightforward. A deficiency is
defined in reference to a control. Neither scar is observable
in patients, nor in the normal nontrauma tissues used as
controls in our studies. Scarring is an emergent function
of tissues; a cell does not scar, but tissue does. Therefore,
the observation of a mature scar is also not common in
experimental cell culture studies.
A critical missing step in our
therapeutic strategies is the normalization of the healing
process through the formation of its endpoint, the functional
scar. It is necessary to resolve this issue to make palliative
therapies curative.
scar.
The scarring process is a necessary contributor to brain healing. The scar is not a consequence but a factor in the healing process. The formation of a mature glial scar takes several weeks to reach completion and requires the absence of exacerbating injury.[5] The spread of invasive cancer cells and therapy‑induced tissue damages are such exacerbating injuries. A largely overlooked point is that although invasive brain tumors elicit reactive gliosis, they are not surrounded by a well‑defined astrocyte or fibrotic scar. The question arises as to why we have neglected to consider the resolution of the scarring process into a mature scar as a therapeutic imperative.
brain tumors elicit reactive gliosis, they are not surrounded by
a well-defined astrocyte or fibrotic scar.
In the words of Hippocrates, “Medicine consists of adding
and subtracting, subtracting what is in excess, adding what
is deficient.” In glioblastoma, the readily observable excess
to subtract is the tumor mass. This may have led us to focus
our therapeutic efforts on subtractive treatments such as tumor
resection and killing cancer cells. To observe a deficiency
like a scar defect is less straightforward. A deficiency is
defined in reference to a control. Neither scar is observable
in patients, nor in the normal nontrauma tissues used as
controls in our studies. Scarring is an emergent function
of tissues; a cell does not scar, but tissue does. Therefore,
the observation of a mature scar is also not common in
experimental cell culture studies.
A critical missing step in our
therapeutic strategies is the normalization of the healing
process through the formation of its endpoint, the functional
scar. It is necessary to resolve this issue to make palliative
therapies curative.