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A Brun

Publications and source records attributed to A Brun.

At least 19 recordsLinked to original sources
PubMed1998

How to better define the characteristics of dispersion of results in liquid chromatographic analyses through an interlaboratory study. Example of collaborative studies on ketoprofen and spiramycin.

The aim of this study was to use statistical tools, especially the analysis of variance (ANOVA), to improve knowledge of the characteristics of the dispersion of results in high-performance liquid chromatography (HPLC) methods for quantitative analysis. It is in this regard that two interlaboratory studies have been carried out in collaboration with Rhône-Poulenc Rorer. The first concerned the analysis of a single drug product (ketoprofen) and was typically a "simple analysis". The second one involved a complex mixture of drug products and related substances (spiramycin), requiring far more constraining analysis conditions. Preliminary studies of the analyses were carried out to develop an optimized protocol. Statistical exploitation of the data for ketoprofen showed that there was no significant influence of the factors "laboratory" and "preparation", under the conditions of the study. On the other hand, in the case of spiramycin, a significant influence of the factors "laboratory" and "preparation" was observed under the conditions of the collaborative study, indicating that the latter factor must be taken into account to establish certified assays. Results of these two studies will help to determine the factors that have a significant influence, depending on the product and the chromatographic method used. By completing the statistical data base, interlaboratory studies will also contribute in the near future to the elaboration of more rigorous protocols for analytical transfers.

Chromatography, High Pressure Liquid↗
PubMed1998

The African swine fever virus proteins p54 and p30 are involved in two distinct steps of virus attachment and both contribute to the antibody-mediated protective immune response.

The nature of the initial interactions of African swine fever (ASF) virus with target cells is only partially known, and to date only the ASF virus protein p12 has been identified as a viral attachment protein. More recently, antibodies to viral proteins p54 and p30 have been shown to neutralize the virus, inhibiting virus binding and internalization, respectively. Therefore, we investigated the role of these proteins in the receptor-mediated ASF virus endocytosis in swine macrophages, the natural host cells. Proteins p54 and p30, released from ASF virus particles after treatment of virions with a nonionic detergent, bound to virus-sensitive alveolar pig macrophages. Binding of these proteins was found to be specifically inhibited by neutralizing antibodies obtained from a convalescent pig or from pigs immunized with recombinant p54 or p30 proteins. The baculovirus-expressed proteins p54 and p30 retained the same biological properties as the viral proteins, since they also bound specifically to these cells, and their binding was equally inhibited by neutralizing antibodies. Binding of 35S-labeled recombinant p54 and p30 proteins to macrophages was specifically competed by an excess of unlabeled p54 and p30, respectively. However, cross-binding inhibition was not observed, suggesting the existence of two different saturable binding sites for these proteins in the susceptible cells. In addition, protein p54 blocked the specific binding of virus particles to the macrophage, while protein p30 blocked virus internalization. Both proteins independently prevented virus infection and in a dose-dependent manner, suggesting that binding interactions mediated by both proteins are necessary to give rise to a productive infection. The relevance of blockade of virus-cell interactions mediated by p54 and p30 in the protective immune response against ASF virus was then investigated. Immunization of pigs with either recombinant p54 or p30 proteins induced neutralizing antibodies which, as expected, inhibited virus attachment or internalization, respectively. However, immunized pigs were not protected against lethal infection and the disease course was not modified in these animals. In contrast, immunization with a combination of p54 and p30 proteins simultaneously stimulated both virus neutralizing mechanisms and modified drastically the disease course, rendering a variable degree of protection ranging from a delay in the onset of the disease to complete protection against virus infection. In conclusion, the above results strongly suggest that proteins p54 and p30 mediate specific interactions between ASF virus and cellular receptors and that simultaneous interference with these two interactions has a complementary effect in antibody-mediated protection.

African Swine Fever↗
PubMed1998

A 50-year perspective of a family with chromosome-14-linked Alzheimer's disease.

A Swedish family with two generations suffering from presenile dementia with an unusually severe Alzheimer encephalopathy was first reported in 1946. The hypothesis that the disease was inherited through a dominant gene is strongly supported by the follow-up 50 years later of three additional generations and molecular genetic findings of a novel presenilin-1 gene mutation in the family. The pedigree contains six cases with well-documented dementia in four consecutive generations. The Alzheimer encephalopathy was unusually severe in the three cases studied post-mortem, with a pronounced involvement of the central grey structures, such as the claustrum, the nuclei around the third ventricle, the central thalamic nuclei and the brain stem. There were no vascular lesions and little amyloid angiopathy. All six affected cases showed the typical temporoparietal symptom pattern and other core symptoms of Alzheimer's disease, such as logoclonia, myoclonic twitchings and major motor seizures. Other predominant features were psychomotor slowness, increased muscular tension, a stiff stooped gait and a rapid loss of weight. The symptom pattern is convincingly explained by the consistent and severe involvement of cortical and central grey structures and is probably linked to the presenilin-1 gene mutation.

Alzheimer Disease↗
PubMed1998

Induction of cytochrome P450 activities in Drosophila melanogaster strains susceptible or resistant to insecticides.

We analysed Drosophila melanogaster cytochrome P450s (P450) through the measurements of four enzymatic activities: ethoxycoumarin-O-deethylase, ethoxyresorufin-O-deethylase, lauric acid hydroxylation, and testosterone hydroxylation. We did these measurements in two Drosophila strains: one is susceptible to insecticides (Cantons) and the other is resistant to insecticides by enhanced P450 activities (RDDTR). In addition, we also treated the flies with eight chemicals (beta-naphtoflavone, benzo-alpha-pyrene, 3-methylcholanthrene, phenobarbital, aminopyrine, rifampicin, prochloraz, and clofibrate) known to induces genes from the families CYP1, CYP2, CYP3, CYP4, and CYP6. Metabolisation of all the substrates by P450 from flies microsomes was observed. The chemicals had different effects on these activities, ranging from induction to inhibition. The effects of these chemicals varied with the strains as most of them were ineffective on the RDDTR strain. The results showed that P450-dependent activities are numerous in Drosophila. Regulation features of these activities are complex. The availability of mutant strains as RDDTR should allow fundamental studies of P450 in insects.

Animals↗
PubMed1998

Physiology of organic nitrogen acquisition by ectomycorrhizal fungi and ectomycorrhizas.

Ectomycorrhizal fungi are symbiotically associated microorganisms which ecological importance has been repeatedly demonstrated. There has been a considerable amount of research aimed at assessing the ability of ectomycorrhizal fungi and ectomycorrhizas to utilize organic nitrogen sources. The fate of soil proteins, peptides and amino acids has been studied from a number of perspectives. Exocellular hydrolytic enzymes have been detected and characterized in a number of ectomycorrhizal and ericoid fungi. Studies on amino acid transport through the plasma membrane have demonstrated the ability of ectomycorrhizal fungi to take up the products of proteolytic activities. Investigations on intracellular metabolism of amino acids have allowed the identification of the metabolic pathways involved. Possible intracellular compartmentation of amino acids will be examined by immunocytochemistry. Further translocation of amino acids in symbiotic tissues has been established by experiments using isotopic tracers, although the exact nature of the nitrogenous compounds transferred at the symbiotic interface remained unclear. One of the main future challenges in the physiology of organic nitrogen acquisition is to determine the nature, the regulation and the location of N-compound transporters at the soil-fungus and fungus-plant interfaces. The molecular approach which is just emerging in this particular research area will greatly improve our knowledge. Future research should also address the extent of competition between different ectomycorrhizal species and between different microbial populations for organic nitrogen.

Amino Acids↗
PubMed1998

Uniform abnormalities in the hippocampus of five chronic schizophrenic men compared with age-matched controls.

In a post-mortem study five chronic schizophrenic men were matched with respect to age and sex to five control subjects without a known history of psychiatric illness, and were compared in pairs with regard to neurone number and pyramidal cell orientation in the left hippocampus. All five schizophrenics had significantly more disoriented pyramidal cells in the Cornu Ammonis subregions CA1-CA3 than their matched controls. They also had significantly fewer pyramidal cells in the observed areas of CA1 and CA3, but not in CA2 and CA4. There was no difference in the number of granular cells of the dentate gyrus. In pairwise comparisons the pattern was never reversed with respect to these two parameters, except in a single case where one schizophrenic proband had more cells in subregion CA2. In the absence of gliosis the findings were interpreted as sequelae of an early, presumably prenatal, injury.

Aged↗
PubMed1998

Functionality and cell anchorage dependence of the African swine fever virus gene A179L, a viral bcl-2 homolog, in insect cells.

The African swine fever virus gene A179L has been shown to be a functional member of the ced9/bcl-2 family of apoptosis inhibitors in mammalian cell lines. In this work we have expressed the A179L gene product (p21) under the control of the baculovirus polyhedrin promoter using a baculovirus system. Expression of the A179L gene neither altered the baculovirus replication phenotype nor delayed the shutoff of cellular protein synthesis, but it extended the survival of the infected insect cells to very late times postinfection. The increase in cell survival rates correlated with a marked apoptosis reduction after baculovirus infection. Interestingly, prevention of apoptosis was observed when recombinant baculovirus infections were carried out in monolayer cell cultures but not when cells were infected in suspension, suggesting a cell anchorage dependence for p21 function in insect cells. Cell survival was enhanced under optimal conditions of cell attachment and cell-to-cell contact as provided by extracellular matrix components or poly-D-lysine. Since it was observed that cytoskeleton organization varied depending on culture conditions of insect cells (grown in monolayer versus grown in suspension), these results suggested that A179L might regulate apoptosis in insect cells only when the cytoskeletal support of intracellular signaling is maintained upon cell adhesion. Thus, cell shape and cytoskeleton status might allow variations in intracellular transduction of signals related to cell survival in virus-infected cells.

African Swine Fever Virus↗
PubMed1997

Study of the metabolism of spiramycin in pig liver.

A major metabolic pathway of spiramycins in pig liver is described. This biochemical reaction involves L-cysteine--a common amino acid present in most animal tissues--which reacts with the aldehyde function of the antibiotic forming a thiazolidine ring. This transformation of spiramycin derivatives drastically increased their polarity. A preliminary HPLC method enabling the quantitation of each metabolite in the range 0.5 microg/g of liver tissue is proposed. Spiramycin S is used as an internal standard while extraction procedures take into account the physico-chemical properties of the thiazolidine moieties. By comparison, previous HPLC methods underestimated the exact amount of antibiotic residues because these metabolites were not extracted from the studied tissues.

Acetonitriles↗
PubMed1997

Whole-body hyperthermia and ADPRT inhibition in experimental treatment of brain tumors.

Malignant primary brain tumors have hitherto been incurable. One reason for this may be the migrating tumor cells that spread into the surrounding normal brain, creating the basis for inevitable recurrences. Therefore, local therapy may have a temporary effect, but for a cure, the treatment must reach all the tumor cells. Whole-body hyperthermia (WBH) is such a general treatment, which we have studied in a rat glioma model. Cells of the RG2 rat glioma cell line were inoculated in the right caudate nucleus of Fischer-344 rats, which were then either controls or treated with WBH, induced by a radiant heat device for 4-5 sessions of 30 min at body temperature 42 degrees C (rectal), and/or nicotinamide (NAM), an effective radiosensitizer in animal tumor models and an inhibitor of ADPRT (poly adenosine diphosphate ribosyl transferase), a chromatin-bound enzyme suggested to be important in the DNA repair system. We have shown that WBH 42 degrees C alone, or in combination with NAM, has no effect upon tumor growth if a larger number of RG2 cells (5,000) are inoculated. If only 1,000 cells are inoculated, a significant inhibitory effect (p < 0.05) is observed on tumor growth as compared to the untreated control animals. Thus, WBH is feasible, and in some circumstances effective, in a rat glioma model. WBH in combination with other therapies influencing cell metabolism may be of value in future postoperative treatment of human malignant brain tumors.

Animals↗
PubMed1997

Clinical characteristics of a chromosome 17-linked rapidly progressive familial frontotemporal dementia.

OBJECTIVE: To describe symptoms, signs, neuroimaging results, and neuropathologic findings in patients from a family with chromosome 17q21-linked autosomal dominant frontotemporal dementia. DESIGN: Multiple case report with genetic investigations. SUBJECTS: The disease was observed in a Swedish family and documented in 3 generations. Four siblings are described in this article. RESULTS: A rapidly progressive dementia with genetic linkage to chromosome 17q21 was observed. The mean age of onset was 51 years and the average duration of disease to death was 3 years. Two patients started with speech disturbances leading to a progressive, nonfluent aphasia, 1 patient had onset symptoms of leg apraxia and akinesia and muscular rigidity, and in 1 patient reckless driving was the first symptom. Loss of spontaneous speech developed later in all patients and emotional bluntness in 3 of the patients. Cerebral perfusion was decreased in the frontal areas in all patients. In the person with apraxia as the onset symptom, the cerebral blood flow was also diminished in the left hemisphere, where a slight atrophy was detected on magnetic resonance imaging scans. At the postmortem examination, slight gliosis of the parietal lobes was observed in this patient. In all patients there was a frontocentral degeneration of the cortex with discrete microvacuolation and gliosis. CONCLUSION: Clinical features of frontotemporal dementia, parkinsonism, an early age of onset, a rapid disease progression, and variable onset symptoms were seen in these patients. Two other clinically distinct diseases, dementia with pallido-ponto-nigral degeneration and a disinhibition-dementia-parkinsonism-amyotrophy complex, have recently been mapped to chromosome 17q21. In the family described in this article, genetic linkage was detected to the same region, suggesting the possibility that these diseases may originate from pathogenic mutations in the same gene.

Chromosomes, Human, Pair 17↗
PubMed1997

Hippocampal pyramidal cell disarray correlates negatively to cell number: implications for the pathogenesis of schizophrenia.

Brains from patients with therapy-refractory schizophrenia were examined with respect to pyramidal cell disarray in the hippocampus, a finding reported in some studies, but not confirmed in others. A significantly higher number of disarrayed cells was seen in the brains of the schizophrenic patients in all subfields of the Cornu Ammonis (CA) investigated. Compared with controls the schizophrenic patients also had significantly fewer pyramidal cells in the observed areas of CA1-CA3, but not in CA4. There were no signs of gliosis. Finally, there was a significant negative correlation between the number of disarrayed cells and the total number of pyramidal cells in CA1-3 in the group of probands and controls taken together, a finding interpreted as lending support to the idea of a prenatal migratory disturbance in the pathogenesis of schizophrenic syndromes.

Aged↗
PubMed1997

High level expression of the major antigenic African swine fever virus proteins p54 and p30 in baculovirus and their potential use as diagnostic reagents.

At present, the eradication of African swine fever (ASF) in affected countries is based only on an efficient diagnosis program because of the absence of an available vaccine. The highly antigenic ASF virus proteins p54 and p30, encoded by genes E183L and CP204L respectively, were expressed in baculovirus for diagnostic purposes. A sequence comparison analysis of these genes from different field virus strains which are geographically diverse and isolated in different years, revealed that both genes are completely conserved among the isolates. Partially purified baculovirus-expressed proteins were used in ELISA and Western blot for ASF antibody detection in sera from experimentally inoculated pigs and field sera from ASF innaparent carriers. These comparative analyses showed that p54 presents better reactivity than p30 in Western blot. However, recombinant p30 was more efficient for antibody detection by ELISA, improving the discrimination between positive and negative sera by this technique. These data suggest the convenience of using p30 as ELISA antigen, while p54 should be the selected antigen for ASF virus antibody detection by Western blot. The combined use of both antigens for serodiagnosis of ASF disease will improve the sensitivity of innaparent carriers detection, facilitating also the interpretation of the tests, and eliminating the use of ASF virus in antigen production.

African Swine Fever↗
PubMed1997

The Drosophila cytochrome P450 gene Cyp6a2: structure, localization, heterologous expression, and induction by phenobarbital.

The cytochrome P450 gene Cyp6a2 from Drosophila melanogaster is located on the right arm of chromosome 2 at position 43A1-2 and comprises two exons separated by a 69-bp intron. Phenobarbital treatment of flies leads to a rapid increase in the level of CYP6A2 mRNA and to an increased production of the CYP6A2 protein. DNA from the Cyp6a2 promoter region was functional when linked to a luciferase reporter gene and transfected into D. melanogaster Schneider cells. Moreover, a dose-dependent induction of luciferase activity by phenobarbital indicated that elements necessary for phenobarbital induction are located within 428 bp of the translation start site. Heterologous expression of the CYP6A2 protein in lepidopteran cells infected with a Cyp6a2-recombinant baculovirus was observed by Western blotting of cell lysates and by spectral characterization of the reduced-CO complex of the P450. The CYP6A2 protein produced in this system metabolized aldrin and heptachlor to their epoxides and metabolized the insecticide diazinon by desulfuration to diazoxon and by oxidative ester cleavage to 2-isopropyl-4-methyl-6-hydroxypyrimidine. Metabolism in lysates of cells infected with recombinant baculovirus was greatly enhanced by the addition of purified housefly NADPH cytochrome P450 reductase and cytochrome b5. These results show that CYP6A2 catalyzes the metabolism of organophosphorus insecticides and they implicate Cyp6a2 overexpression in metabolic resistance. The Cyp6a2 gene appears to be a suitable model for a genetic analysis of the phenobarbital induction process.

Aldrin↗
PubMed1997

Cytochrome P-450 field insecticide tolerance and development of laboratory resistance in grape vine populations of Drosophila melanogaster (Diptera: Drosophilidae).

Studies were conducted between 1993 and 1996 using 3 natural grape vine populations, 1 susceptible laboratory strain, and 1 resistant selected strain of Drosophila melanogaster L. In vitro monooxygenase activity (ethoxycoumarine-O-deethylation) (ECOD) was recorded from microsomal fractions of all strains. Results varied over a 6-fold range between susceptible laboratory Canton and resistant selected RDDT strains and over a 2-fold range between the Canton strain and natural populations of flies. Few significant variations of ECOD activity were detected among the natural populations despite many insecticide treatments, but activities were significantly correlated with toxicological tolerance to 5 of the 15 insecticides (deltamethrin, fipronil, chlorpyriphos ethyl, DDT, and diazinon). Moreover, immunoblotting responses of microsomal protein encoded by Cyp6A2 showed that the levels of expression were quantitatively correlated with toxicological tolerance to almost the same group of insecticides (deltamethrin, fipronil, chlorpyriphos ethyl, DDT, fenvalerate, and fenthion). However, the level of CYP6A2 expression in some natural strains (still weakly resistant) was almost comparable with one of the resistant strains. In vivo monooxygenase activity recorded in individual abdomens of flies showed that frequency distributions of ECOD activity in natural populations overlapped those of the resistant and laboratory strains, which were much narrower. Substantial and fast frequency changes (of the narrowness) that obtained in laboratory were related to either the time of rearing of 1 of the natural populations or selecting this population with an insecticide that has a toxicology correlated with both of the monooxygenase signs measured. Perspectives on using the CYP6A2 expression and ECOD activity for detecting a resistance mechanism by cytochrome P450 in field populations are discussed.

Animals↗
PubMed1997

Patterns of azathioprine metabolites in neutrophils, lymphocytes, reticulocytes, and erythrocytes: relevance to toxicity and monitoring in recipients of renal allografts.

Monitoring of azathioprine (AZA) therapy by the measurement of 6-thioguanine nucleotides (6-TGN) concentrations in red blood cells (RBC) may improve safety and ensure optimal immunosuppressive effects of AZA in organ transplantation. The authors explored the rationale for such monitoring by measuring thiopurine metabolites in peripheral blood cell types that are more relevant to the effects and kinetics of AZA and its active metabolites. Neutrophil granulocytes were isolated by density gradient centrifugation, and CD4+ lymphocytes and reticulocytes by using specific immunomagnetic beads. In neutrophils, 6-TGN concentrations had median measurements 31 times higher than in RBCs. In contrast to the high methylated mercaptopurine (me-MP) concentrations in RBCs, these metabolites were not detected in the neutrophils. Thiopurine metabolite levels were lower than the analytic limit of detection in all the CD4+ samples. The concentrations of 6-TGN and me-MPs were lower in reticulocytes than in RBCs in general, indicating that thiopurine metabolites are taken up by RBCs in the circulation. This study's findings, that 6-TGN concentrations are very high in neutrophils, whereas me-MPs are undetectable, many explain the specific neutropenic adverse effect of AZA. The results also add support to monitoring AZA through measurements of 6-TGN and me-MPs in RBCs.

Aged↗
PubMed1997

Evaluation of malignancy in ring enhancing brain lesions on CT by thallium-201 SPECT.

OBJECTIVE: To investigate patients with cystic enhancing lesions on CT and to determine whether thallium-201 (201Tl) SPECT adds to further preoperative information in differential diagnosis between gliomas and abscesses. METHODS: Twenty one patients with cystic ring enhancing CT findings were studied and uptake indices were compared with CT enhancement volumes, histopathology, and survival times. RESULTS: Fourteen high grade gliomas, three low grade gliomas, and four abscesses were found. Uptake was higher in the highly malignant glioma group (median thallium index (TI)=2.1), than in the low grade glioma group (median TI=1.4) or among the abscesses (median TI=1.6). Overlapping indices were found between high and low malignant cystic gliomas as well as between either one of the glioma groups and the infectious lesions, and there were no significant differences between groups. There was a level at the value 2, where TI > or = 2 correlated with tumour diagnosis. One low grade tumour had an extremely high index and a very high enhancement volume. Indices correlated significantly with CT enhancement volumes (P=0.005). There was no significant correlation between Tl indices and patient survival times among the high grade gliomas. One patient with a highly malignant tumour but low Tl uptake < 2, had a survival > five years. CONCLUSIONS: It is concluded that high 201Tl uptake in enhancing cystic lesions is an indicator of highly malignant glioma. However, the differentiation between the high malignant gliomas and abscesses or low malignant gliomas by 201TL SPECT is only partial with an overlap between these groups.

Adult↗