Biomedical subjects

O Bernard

Publications and source records attributed to O Bernard.

At least 19 recordsLinked to original sources

PubMed2000

TEL-JAK2 transgenic mice develop T-cell leukemia.

We previously reported a fusion between TEL and JAK2 in a t(9;12)(p24;p13) chromosomal translocation in childhood acute T-cell leukemia. This fusion gene encodes a TEL-JAK2 chimeric protein in which the 336 amino-terminal residues of TEL, including its specific self-association domain, are fused to the kinase domain of JAK2. TEL-JAK2 exhibits constitutive activation of its tyrosine kinase activity which, in turn, confers growth factor-independent proliferation to the interleukin-3-dependent Ba/F3 hematopoietic cell line. To elucidate the properties of TEL-JAK2 in primary cells and to create an animal model for TEL-JAK2-induced leukemia, we generated transgenic mice in which the TEL-JAK2 complementary DNA was placed under the transcriptional control of the EmuSRalpha enhancer/promoter. TEL-JAK2 founder mice and their transgenic progeny developed fatal leukemia at 4 to 22 weeks of age. Selective amplification of CD8-positive T cells was observed in blood, lymph nodes, thymus, spleen, and bone marrow. Expression of a tyrosine-phosphorylated TEL-JAK2 protein and activation of STAT1 and STAT5 (signal transducer and activator of transcription) were detected in leukemic tissues. TEL-JAK2 diseased mice also displayed invasion of nonhematopoietic organs, including liver, brain, lung, and kidney, by leukemic T cells. Leukemic organs of founder and transgenic progeny contained a monoclonal/oligoclonal T-cell population as analyzed by the rearrangement of the TCRbeta locus. Transplantation of TEL-JAK2 leukemic cells in nude mice confirmed their invasive nature. We conclude that the TEL-JAK2 fusion is an oncogene in vivo and that its expression in lymphoid cells results in the preferential expansion of CD8-positive T cells. (Blood. 2000;95:3891-3899)

Animals↗

PubMed2000

Implication of Bcl-2 and Caspase-3 in age-related Purkinje cell death in murine organotypic culture: an in vitro model to study apoptosis.

Neuronal cell death is an essential feature of nervous system development and neurodegenerative diseases. Most Purkinje cells in murine cerebellar organotypic culture die when taken from 1-5-day-old mice (P1-P5), whereas they survive when taken before or after these ages. Using DNA gel electrophoresis, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) and electron microscopic analyses, we were able to show that this massive Purkinje cell death is apoptotic in nature and reaches a peak at P3. From the several endogenous genes known to be involved in the apoptotic process, we have focused on two: the bcl-2 and the caspase-3 that encode for anti-apoptotic and pro-apoptotic proteins, respectively. Immunostaining for activated Caspase-3 correlated with Purkinje cell death. A better survival of Purkinje cells was observed in P3 slices taken from hu-bcl-2 transgenic mice, and in slices treated with z-DEVD.fmk (an inhibitor of numerous caspases). Thus, these two genes are implicated in the age-related Purkinje cell apoptosis in organotypic culture. As Purkinje cell death in vitro takes place at the same age as Purkinje cells engaged in intense synaptogenesis and dendritic remodeling in vivo, we propose that this apoptosis reflects a naturally occurring Purkinje cell death during this critical period.

Animals↗

PubMed2000

Human Bcl-2 protects against AMPA receptor-mediated apoptosis.

Dysfunctions of the (S)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) subtype of ionotropic receptor for the brain's major excitatory neurotransmitter, L-glutamate, occur in various neurological conditions. We have previously demonstrated that AMPA receptor-mediated excitotoxicity occurs by apoptosis and here examined the influence of the expression of cell death repressor gene Bcl-2 on this excitotoxic insult. Using neuronal cortical cultures prepared from transgenic mice expressing the human Bcl-2 gene, the influence of Bcl-2 on AMPA receptor-mediated neuronal death was compared with that seen with staurosporine and H2O2. At day 6 cultures were exposed to AMPA (0.1-100 microM), and cellular injury was analyzed 48 h after insult using phase-contrast microscopy, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide viability assay, and DNA staining with 4,6-diamidino-2-phenylindole and Sytox Green. AMPA produced a concentration-dependent increase in cell death that was significantly attenuated by human Bcl-2. AMPA (3 microM) increased the number of apoptotic nuclei to 60% of control in wild-type cultures, and human Bcl-2 significantly decreased the number of apoptotic nuclei to 30% of AMPA-treated cultures. Human Bcl-2 only provided significant neuroprotection against neuronal injury induced by low concentrations of staurosporine (1-10 nM) and H2O2 (0.1-30 microM) and where neuronal death was by apoptosis, but not against H2O2-induced necrosis. Our findings indicate that overexpression of Bcl-2 in primary cultured neurons protects in an insult-dependent manner against AMPA receptor-mediated apoptosis, whereas protection was not seen against more traumatic insults. This study provides new insights into the molecular therapeutics of neurodegenerative conditions.

Animals↗

PubMed2000

Determination of the velocity associated with VO2max.

PURPOSE: The theoretical velocity associated with VO2max (vVO2max) defined by Daniels (1985) is extrapolated from the submaximal VO2-velocity relationship. VO2 is generally determined by assuming that the aerobic response reacts like a linear first-order system at the beginning of square-wave exercise with a steady-state reached by the 4th minute. However, at supra-ventilatory threshold work rates, the steady state in VO2 is delayed or not attained. METHODS: The present study was carried out to compare three values for vVO2max determined with Daniels' method, but with VO2 either measured at the 4th minute (vVO2max4), the 6th minute (vVO2max6), or after the attainment of the true steady-state (vVO2maxSS). The metabolic response during square-wave exercise at each of the three vVO2max were also assessed. RESULTS: These velocities were significantly different (P < 0.05), but vVOmaxSS and vVO2max6 were highly correlated (r = 0.98; P < 0.05). Blood lactate concentrations measured after exercise at velocities very close to the three vVO2max were similar and the end-exercise VO2 were not different from VO2max, but the time required to elicit 95% VO2max during these three square-wave tests were significantly different. CONCLUSION: Therefore, when vVO2max is determined by extrapolation from the submaximal VO2-velocity relationships, submaximal VO2 should be measured beyond the 6th minute of square-wave exercise (at least if it takes 30 s to reach the desired velocity) to ensure that all vVO2max reported in future studies describe a similar quantitative index.

Adult↗

PubMed2000

Risk of gastrointestinal bleeding during adolescence and early adulthood in children with portal vein obstruction.

OBJECTIVE: To estimate the risk of bleeding during adolescence and early adulthood in a group of children with portal vein obstruction who had not undergone an effective treatment beforehand. STUDY DESIGN: Children (n = 44) were followed up from age 12 years to a mean age of 20 years (range, 15-34 years). Actuarial risk of bleeding, related to previous occurrence of gastrointestinal bleeding and to pattern of varices at age 12, was calculated yearly. RESULTS: Twenty-four children presented with gastrointestinal bleeding after age 12, and 20 did not bleed. The overall actuarial probability of bleeding was 49% at age 16 and 76% at age 24. Probability of bleeding at age 23 was higher in children who had bled before age 12 than in children who had not bled (93% vs 56%; P =.007). Probabilities of bleeding at age 18 and at age 23 were 60% and 85%, respectively, in patients who had grade II or III esophageal varices at age 12. The 9 children without varices or with grade I varices only on endoscopy did not bleed between the ages of 12 and 20 years. CONCLUSIONS: Children with portal vein obstruction have a >50% risk of bleeding during adolescence; the pattern of varices on endoscopy at age 12 may have a prognostic value.

Actuarial Analysis↗

PubMed2000

[Malignant paraganglioma of the uterus].

We report a malignant uterine paraganglioma in a 41-year-old woman who underwent a hysterectomy for meno-metrorrhagia. It was initially thought to be a leiomyoma in necrobiosis. The clinical outcome was characterized by an early regional recurrence (in the left Fallopian tube). Later, vertebral and lung metastasis occurred, leading to death 22 months after the initial diagnosis. Paragangliomas are uncommon neuroendocrine tumors, related to pheochromocytomas. They are mainly found in the para-aortic and retroperitoneal region, and less commonly in the pelvic area. Location in the uterus is extremely rare: 5 cases were previously reported and only one malignant.

Adult↗

PubMed1999

Interactions between bcl-2 and the IGF system control apoptosis in the developing mouse brain.

The IGF system and the pro-survival Bcl-2 proteins protect cells from apoptosis and play a key role in brain development. In order to examine a possible relationship between these two potent anti-apoptotic systems, we utilised two transgenic mice models overexpressing either Bcl-2 or IGF-I proteins in olfactory bulb (OB) or cerebellar neurons, respectively. We have demonstrated that while the organization of the defined layers of the OB from the bcl-2 transgenic and wildtype mice cultured in serum free medium (SF) was similarly poor, the mitral cell layer from the transgenic mice was expanded and their neurons were well preserved. Addition of IGF-I improved the definition of the layers normally present within the OB, in both wildtype and bcl-2 transgenic mice, and restored wildtype mitral cell layer structure and neuronal survival similar to that in bcl-2 mice, whose mitral cell survival was not further enhanced by IGF-I. Immunoreactivity for IGF-I and IGFBP-2 was markedly increased in these Bcl-2-expressing mitral cells compared to wildtype mice. In newborn IGF-I transgenic mice, cerebellar Purkinje cells overexpressing IGF-I showed markedly increased immunoreactivity for Bcl-2 and IGFBP-2. These studies indicate that in the developing brain IGF-I modulates expression of its major binding protein IGFBP-2, as well as the Bcl-2 protein. In addition apoptosis caused by culturing OBs in SF medium, is inhibited by expression of Bcl-2 in the mitral neurons and is associated with enhanced expression of the IGF system, including IGF-I and IGFBP-2. The later may thus play a role in IGF targeting. This complex interaction between the two potent anti-apoptotic systems is likely to provide a robust system of cell protection during brain development and repair.

Animals↗

PubMed1999

Mass balance modeling of vanillin production from vanillic acid by cultures of the fungus Pycnoporus cinnabarinus in bioreactors.

A systematic two-step procedure for the structural identification of bioprocesses is followed in order to establish a mechanistic model for vanillin production by Pycnoporus cinnabarinus. The first step is devoted to the identification of the underlying reaction structure and the development of a validated mass balance model for the growth of P. cinnabarinus and the biotransformation of vanillic acid into vanillin. The second step is devoted to the kinetic modeling, namely, the estimation of the reaction rates and the calibration of the kinetic parameters. The whole procedure leads to the final set up of a simulation model of the process. The results are supported by the data from five cultures of P. cinnabarinus in bioreactors.

Benzaldehydes↗

PubMed1999

Jeune syndrome and liver disease: report of three cases treated with ursodeoxycholic acid.

Three children with Jeune syndrome (asphyxiating thoracic dystrophy) had clinical and laboratory evidence of liver disease. In two patients the disease evolved to biliary cirrhosis, whereas in the third it was recognized when extensive fibrosis was developing. In the three patients, treatment with ursodeoxycholic acid appeared to control the progression of the hepatic dysfunction.

Alanine Transaminase↗

PubMed1999

TEL is a sequence-specific transcriptional repressor.

TEL is a gene frequently involved in specific chromosomal translocations in human leukemia and sarcoma that encodes a member of the ETS family of transcriptional regulators. TEL is unusual among other ETS proteins by its ability to self-associate in vivo, a property that is essential to the oncogenic activation of TEL-derived fusion proteins. We show here that TEL is a sequence-specific transcriptional repressor of ETS-binding site-driven transcription of model and natural promoters. Deletion of the oligomerization domain of TEL or its substitution by the homologous region of monomeric ETS1 impaired the ability of TEL to repress. In contrast, substitution of the oligomerization domain of TEL by unrelated oligomerization domains resulted in an active repressor, showing that the ability of TEL to repress depends on its ability to self-associate. The study of the properties of TEL fusions to the heterologous DNA binding domain of Gal4 identified two autonomous repression domains in TEL, distinct from its oligomerization domain, that are essential to the ability of TEL to repress ETS-binding site-containing promoters. These results have implications for the normal function of TEL, its relation to other ETS proteins, and its role in leukemogenesis.

Animals↗

PubMed1999

Bcl-2 transgenic mice with increased number of neurons have a greater learning capacity.

Transgenic mice overexpressing Bcl-2 in their neurons have an increased number of neurons. To assess whether this increased number of neurons leads to increased learning capacity we have used the Hebb-Williams maze which provides a measure of learning suitable for the study of small animals. We have demonstrated that bcl-2 transgenic mice learn faster and are more accurate in this maze. They required fewer trials to complete the maze and committed fewer errors. The transgenic mice were also faster than the wildtype mice, in particular the older mice. Prior to learning both groups of mice behaved in a similar way. These results show that bcl-2 transgene expression enhances learning capacity in mice by increasing the number of neurons.

Analysis of Variance↗

PubMed1999

Non-linear qualitative signal processing for biological systems: application to the algal growth in bioreactors.

We present in this paper a qualitative method to validate and monitor the structure of a non-linear model with respect to experimental data, under some hypotheses. This method is broadly independent of the analytical formulation of the model, and depends only on the qualitative structure (the signs of the Jacobian matrix). The temporal sequences of the extrema of a filtered experimental signal are compared with the transitions allowed by a graph. In particular, we show that the usual moving average of the outputs follows this transition graph. We apply this method to compare models of algal growth in a bioreactor with experimental data.

Bioreactors↗

PubMed1999

Bcl-2 overexpression protects the neonatal cerebellum from ethanol neurotoxicity.

The developing nervous system is extremely sensitive to ethanol, and exposure often produces a condition known as the fetal alcohol syndrome. Although mechanisms underlying developmental ethanol toxicity have long been sought, they remain poorly understood. In this study, we examined the ability of the cell death repressor gene bcl-2 to protect against ethanol neurotoxicity. Transgenic mice overexpressing bcl-2 in neurons were exposed to ethanol vapor on postnatal days 4 and 5, which is the peak period of vulnerability of cerebellar Purkinje cells to ethanol. While exposure of wild-type animals to ethanol resulted in significant loss of Purkinje cells by P5, similar exposure of homozygous and heterozygous transgenics had no effect on the number of these neurons. This study suggests that bcl-2 can protect neurons from ethanol neurotoxicity and that modulation of cell death effector or repressor gene products may play a significant role in developmental ethanol neurotoxicity.

Analysis of Variance↗

PubMed1999

Identification of three novel mutations (Q54P, W70X and T108I) in the glucose-6-phosphatase gene of patients with glycogen storage disease type Ia. Mutation in brief no. 256. Online.

Three novel mutations, Q54P, W70X and T1081, were identified in the gene encoding glucose-6-phosphatase in three patients with glycogen storage disease type Ia. Two sibs of Portuguese origin were homozygous for the Q54P mutation whereas the third patient, originating from both France and Lebanon, was a compound heterozygote for the W70X and T108I mutations. Glycogen storage disease type Ia is a heterogeneous autosomal recessive condition.

Glucose-6-Phosphatase↗

PubMed1999

Liver transplantation in mitochondrial respiratory chain disorders.

UNLABELLED: Mitochondrial respiratory chain disease may lead to neonatal or late onset liver failure, requiring liver transplantation. In rare cases, the disease is restricted to the liver and the patient is cured after surgery. More frequently, other organs are simultaneously involved and neuromuscular or other extra-hepatic symptoms may pre-exist, or appear in the post-transplant follow up. Pre-transplant evaluation should aim to rule out neurological disease, which may be difficult to differentiate from signs accompanying liver insufficiency. Cerebrospinal fluid lactic acid levels, compared to blood lactate, may be suggestive of central nervous system involvement. Of 11 cases with respiratory chain disorders who had liver transplantation in various centres, 4 are alive and well on follow up, and 6 died, three of them having developed neurological disease post orthotopic liver transplantation. All three patients with initial liver and gastro-intestinal disease died early after transplantation, indicating that these may be poor candidates for this procedure. CONCLUSION: Liver transplantation is feasible in hepatic respiratory chain disorders, but extra-hepatic disease should be ruled out before transplantation. Extra-hepatic manifestations may, however, appear and cause patient death despite successful transplantation.

Electron Transport↗

PubMed1999

Mutations in JAGGED1 gene are predominantly sporadic in Alagille syndrome.

BACKGROUNDS & AIMS: Mutations in the JAGGED1 gene are responsible for the Alagille syndrome, an autosomal dominant disorder characterized by neonatal jaundice, intrahepatic cholestasis, and developmental disorders affecting the liver, heart, vertebrae, eyes, and face. We screened a large group of patients for mutations in JAGGED1 and studied transmission of the mutations. METHODS: The coding sequence of the JAGGED1 gene was searched by single-strand conformation polymorphism and sequence analysis for mutations in 109 unrelated patients with the Alagille syndrome and their family if available. RESULTS: Sixty-nine patients (63%) had intragenic mutations, including 14 nonsense mutations, 31 frameshifts, 11 splice site mutations, and 13 missense mutations. We identified 59 different types of mutation of which 54 were previously undescribed; 8 were observed more than once. Mutations were de novo in 40 of 57 probands. CONCLUSIONS: Most of the observed mutations other than the missense mutations in JAGGED1 are expected to give rise to truncated and unanchored proteins. All mutations mapped to the extracellular domain of the protein, and there appeared to be regional hot spots, although no clustering was observed. Thus, the sequencing of 7 exons of JAGGED1 would detect 51% of the mutations. Transmission analysis showed a high frequency of sporadic cases (70%).

Alagille Syndrome↗

PubMed1999

Ischemic necrosis of bile ducts complicating Schönlein-Henoch purpura.

Gastrointestinal complications of Schönlein-Henoch purpura are frequent and sometimes severe. However, there seem to be no reports of liver involvement. A child is described in whom Schönlein-Henoch purpura was complicated by bile duct lesions, resulting in biliary cirrhosis and requiring liver transplantation. At surgical removal, the liver had lesions of bile ducts and of adjacent small blood vessels in the hilum, very similar to those complicating hepatic artery thrombosis after liver transplantation. These findings suggest that Schönlein-Henoch purpura can be complicated by vasculitis of the peribiliary vessels resulting in ischemic necrosis of the bile ducts. Schönlein-Henoch purpura can be added to the list of causes of ischemic cholangiopathies.

Bile Ducts↗

PubMed1999

Efficacy of cyclosporin A in children with type 2 autoimmune hepatitis.

The conventional treatment of autoimmune hepatitis (AIH) with prednisone and azathioprine induces remission in most cases but is often associated with poorly tolerated side effects. We carried out a retrospective study to evaluate the efficacy of and the tolerance to cyclosporin treatment in 15 children and adolescents with type 2 AIH. Eight children received cyclosporin as primary immunosuppression because of risk factors for poor tolerance of steroids. Five other patients with relapsing AIH refused to resume treatment with steroids and were treated with cyclosporin. In both groups alanine aminotransferase activity returned to normal within 6 months. Side effects were minimal and well tolerated. No relapse occurred in 10 patients after 1 to 6 years. Cyclosporin was withdrawn in 3 patients after 1, 2, and 3 years and replaced by low doses of prednisone in combination with azathioprine. In 2 other children with acute liver failure, which progressed despite treatment with steroids and azathioprine, the addition of cyclosporin was followed by normalization of prothrombin time.

Adolescent↗