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Biomedical subjects

G Brun

Publications and source records attributed to G Brun.

At least 109 records · Page 6Linked to original sources
PubMed1981

DNA topoisomerase I from mitochondria of Xenopus laevis oocytes.

Activity of DNA topoisomerase I has been characterized in extracts of mitochondria purified from Xenopus laevis oocytes. Several lines of evidence have been obtained for the intramitochondrial localization of the enzyme. The mitochondria-associated of DNA topoisomerase I represents 1% of the activity recovered from a total ovary population of oocytes. The enzymes has been purified by DEAE-cellulose, phosphocellulose and double-stranded DNA cellulose chromatography and its properties compared to those of its nuclear-cytosolic counterpart purified by the same purification steps. Both enzymes appear to possess very similar if not identical physico-chemical and catalytic properties. Neither enzyme shows DNA gyrase activity and they are both equally sensitive towards trypanocide drugs such as ethidium bromide and berenil. The mitochondrial enzyme is able to remove positive superhelical turns and possibly acts as a swivelase during replication of mitochondrial DNA. These results confirm the pioneering work of Fairfield et al. (1979, J Biol. Chem. 254, 9354) on the presence of a DNA topoisomerase I in mitochondria. However our results support the conclusion that in Xenopus laevis oocytes the mitochondrial and nuclear cytosolic DNA topoisomerase I are in all likelihood one and the same enzyme.

Animals↗
PubMed1981

Child psychiatric advice to legal authorities concerning custody and post-divorce visiting rights. Results of collaboration of lawyers and child psychiatrists over a 2-year period.

The need of the judicial system for psychiatric and psychological examination of parents and children prior to decisions concerning custody and visiting rights is illustrated. Further, the possibility of establishing collaboration with legal authorities is discussed. Most child psychiatric and child psychological clinics in Denmark declared themselves willing to take part in the investigation carried out during 1975 and 1976. Within this period the legal authorities referred 232 cases. The indication for expert advice is discussed. Our suspicion that the parties in these selected cases often were suffering from serious mental disorders was confirmed. The difficulties of evaluating the child's views are described. The authors conclude that it is impossible to fix a lower limit for the age at which children are to be heard in court. The legal decision usually accorded with the conclusion drawn from the statement. The investigation resulted in the establishment of a more permanent collaboration of lawyers and psychiatric examiners with regard to custody and visiting rights.

Adolescent↗
PubMed1981

[Behavior of an intra-uterine device in the abdomen of animals (author's transl)].

The authors have carried out an experimental study on the reaction of an animal's organism to the presence of an open copper intra-uterine device when placed in the abdomen. The study was carried out on two groups each of 10 rabbits and two bitches. The intra-uterine device was placed in the pouch of Douglas by laparotomy, directly in one group and after contamination with genital secretions in the other. The state of the animals was checked six weeks after the initial laparotomy. Trauma caused by the operation was minimal because there were no adhesions found on the parietal peritoneum. On the other hand in experimental conditions that are very similar to those found when an intra-uterine device goes through the uterus in a human subject and involves contamination with genital secretions, in 50 per cent of cases the intra-uterine device migrated within the abdominal cavity. It was picked up by the omentum and this underwent such a strong fibrous reaction that it brought about multiple intestinal adhesions. Though the authors admit that experimental results in animals cannot be extrapolated to women, they believe that these results should be taken into consideration and that it would be imprudent to leave an intra-uterine device in the abdomen in a woman when there is proof that it has migrated, because there would then be a major risk of intestinal obstruction due to an adhesion that as formed a band.

Animals↗
PubMed1979

Some factors determining the concentration of liver proteins for optimal mutagenicity of chemicals in the Salmonella/microsome assay.

In plate assays in the presence of S. typhimurium TA100 and various amounts of liver 9000 X g supernatant (S9) from either untreated, phenobarbitone- (PB) or Aroclor-treated rats, the S9 concentration required for optimal mutagenicity of aflatoxin B1 (AFB) depended both on the source of S9 and on the concentration of the test compound. In these assays, the water-soluble procarcinogen, dimethylnitrosamine (DMN) was mutagenic in S. typhimurium TA1530 only in the presence of a 35-fold higher concentration of liver S9 from PB-treated rats than that required for AFB, a lipophilic compound. In liquid assays, a biphasic relationship was observed in the mutagenicities in S. typhimurium TA100 of benzo[a]pyrene (BP) and AFB and the concentration of liver S9. For optimal mutagenesis of BP, the concentration of liver S9 from rats treated with methylcholanthrene (MC) was 4.4% (v/v); for AFB it was 2.2% (v/v) liver S9 from either Aroclor-treated or untreated rats. At higher concentrations of S9 the mutagenicity of BP and of AFB was related inversely to the amount of S9 per assay. The effect of Aroclor treatment on the microsomemediated mutagenicity of AFB was assay-dependent: in the liquid assay, AFB mutagenicity was decreased, whereas in the plate assay it did not change or was increased. As virtually no bacteria-bound microsomes were detected by electron microscopy, after the bacteria had been incubated in a medium containing 1-34% (v/v) MC-treated rat-liver S9, it is concluded that, in mutagenicity assays, mutagenic metabolites generated by microsomal enzymes from certain pro-carcinogens have to diffuse through the assay medium before reaching the bacteria. Thus the mutagenicity of BP was dependent on both the concentration of rat-liver microsomes and that of total cytosolic proteins and other soluble nucleophiles such as glutathione. At a concentration of 4.4% (v/v) liver S9, the mutagenicity of BP was about 3.6 times higher than in assays containing a 4-fold higher concentration of cytosolic fraction. Studies on the glutathione-dependent reduction of BP mutagenicity in plate assays has shown that, in the presence of liver S9 concentrations greater than that required for optimal mutagenicity, the reduction in mutagenicity was related directly to the concentration of liver S9. Thus, in the Salmonella/microsome assay, when the concentration of rat-liver S9 was increased over and above the amount required for the optimal mutagenicity of BP, the mutagenic metabolites of BP were inactivated (by being trapped with cytosolic nucleophiles and/or by enzymic conjugation with glutathione); this effect increased more rapidly than their rate of formation. The concentration of liver S9 for optimal mutagenicity of test compounds requiring activation catalyzed by mono-oxygenases seems, therefore, to be related to the departure from linearity of the relationship between the rate of formation of mutagenic metabolites and the concentration of liver S9.

Aflatoxins↗
PubMed1979

Separation and partial characterization of two deoxyribonucleic acid polymerases from Spiroplasma citri.

The separation and partial characterization of two deoxyribonucleic acid polymerases from Spiroplasma citri have been achieved. The two enzymes had different elution properties on diethylaminoethyl (DEAE) cellulose and differed in their sensitivity to N-ethylmaleimide (NEM), preference for different template-primers, and sedimentation velocity in linear glycerol gradients. The first enzyme activity, ScA, was retained on DEAE-cellulose and was not inhibited by NEM. Activated deoxyribonucleic acid and poly(dA)-oligo(dT12) were the preferred template-primers. Arabinosyl-cytidine triphosphate had no effect. The sedimentation coefficient of ScA was 6.3s. The second activity, ScB, was not retained on DEAE-cellulose and was inhibited by NEM. Poly(dA)-oligo(dT12) was the preferred template-primer, whereas activated DNA was only poorly utilized. ScB was not affected by arabinosyl-cytidine triphosphate, and its sedimentation coefficient was 4.4s. The polymerization activities of the two enzymes were maximum at 37 to 40 degrees C.

Arabinofuranosylcytosine Triphosphate↗
PubMed1979

[The evolution of the indications for laparoscopy between 1973 and 1977. 1,758 cases (author's transl)].

In order to avoid the misuse of laparoscopy by an unnecessary increase in the indications for the procedure the authors have reviewed the evolution of these indications in the five years between 1973 and 1977. Certain indications have stayed stable, such as chronic pain in the pelvis, masses found in the pelvis, symptoms suggestive of upper genital tract infection or of ectopic pregnancy and tubal or unexplained sterility. Stability in these indications is correct because laparoscopy and laparoscopy alone can give a precise diagnosis of the lesion and complete the clinical findings and the other methods of investigation. There are two indications which have become less frequent and these are: ovarian sterility and amenorrhoea. This is logical since more reliance has come to be placed on biological methods. Laparoscopy should be reserved in these conditions for cases where are contradictions between biological findings or where there are therapeutic failures. An increase in the indications which is very justified is in those laparoscopies which are carried out as a control of the results of tubal surgery, because there a prognosis can be given and therapy can be carried out (such as division of adhesions) and in cases of malignant tumours of the ovary which, although the procedure will give less precise information than laparotomy, has the advantage that it can be repeated from time to time.

Amenorrhea↗
PubMed1979

[The indications for laparoscopy in malignant tumours of the ovary (author's transl)].

The diagnosis of a malignant ovarian tumour can be made laparoscopically. It is particularly indicated in cases of ascites occurring by itself due to a neoplasm or of undiagnosed origin, and in cases of infiltration of the pelvic nodes or when a small abdominal mass, whether it is isolated or associated with ascites, is found. This particularly of value when a cytological examination of the ascitic fluid does not indicate the diagnosis. Laparoscopy is a means by which the degree of spread of abdomino-pelvic lesions can be discerned in cases where the malignant nature of the ovary is known, but where the prognoses for its removal, either immediately or after several cures with chemotherapy, are doubtful and where the degree of spread has not been correctly and precisely determined at the first surgical intervention. Therefore laparoscopy can complete the information obtained from pelvic examinations and avoid the need for carrying out an exploratory laparotomy, but is gives less information than this latter does about the degree of spread in the pelvis and in the abdomen. So, laparoscopy is a means by which repeated control of the results of therapy which is more thorough than clinical examination can be assured, particularly because it acts as a check on peritoneal cytology. Although its interpretation can be very difficult and its reliability is a relative one, the latter is a good criterion of follow-up.

Ascitic Fluid↗
PubMed1979

Simultaneous occurrence of hereditary C6 and C2 deficiency in a French-Canadian family.

The sera of four sisters were found to lack the sixth component of complement (C6) and the serum of one was also partially deficient in the second component (C2). Two other blood relatives were found to be heterozygous for both deficiencies, while only one sibling had normal values. The father of these eight siblings was heterozygous for C2D and C6D and in the third generation, six children were heterozygous for C6 deficiency was treated for chronic active brucel-transmitted; the C6 deficiency was not linked to the HLA system, while the C2-deficiency segregated with the haplotype A10,B18. The proband, homozygous for C6 deficiency was treated for chronic active Brucellosis and in another sibling with C6 deficiency, toxoplasmosis was diagnosed. Neither bleeding disorders nor a tendency to collagen diseases have been observed and the opsonic activity was normal in the sera of all family members.

Adult↗
PubMed1979

[Leydig cell tumor of the ovary (biologic (in vivo and in vitro) and ultrastructural study) (author's transl)].

The authors present the case of a young hirsute woman of 28 years old. Urinary 17 KS were very increased without DHA, but with androsterone, etiocholanolone and 11 oxy 17 Ketosteroids. Androstenedione and testosterone plasmatic levels were very high and per operative selective ovarian vein catheterization showed a direct production of these potent androgens. In vitro study of the tumor allowed to obtain same results. Light and electron microscopic study showed a Leydig cell tumor of left ovary.

17-Ketosteroids↗
PubMed1978

Initiation of HeLa cell DNA synthesis in a subnuclear system.

Mammalian cells are known to synthesize DNA in discrete stages, the first of which seems to be the formation of DNA pieces 150--200 nucleotides in length that have a s20 value of about 4 S. We have reconstructed a system derived from HeLa cell nuclei that carries out RNA-primed initiation of the synthesis of small (4S) DNA fragments. This synthesis is resistant to high concentrations of alpha-amanitin and sensitive to antibody directed against RNA polymerase I, suggesting that this enzyme may be involved in the initiation step. The formation of small DNA fragments in this system also requires DNA polymerase alpha, heat-labile nuclear factor(s), and at least one other nuclear protein.

Cell Nucleus↗
PubMed1978

Synthesis of viral and host DNA in isolated chromatin from herpes simplex virus-infected HeLa cells.

DNA synthesis in chromatin isolated from herpes simplex virus type 1-infected HeLa cells (HSV chromatin) was examined in vitro. The HSV chromatin was found to carry out an initial limited synthesis of DNA in vitro, 50 to 64 pmol of dTMP incorporated in 10(6) nuclei per 10 min, which is comparable to that found in nuclei isolated from HSV-infected cells. DNA synthesis in vitro proceeded for only 30 min, and both HSV DNA and host DNA were synthesized in significant amounts. The HSV and host DNA synthesis in isolated chromatin were inhibited to the same extent by anti-HSV antiserum or by phosphonoacetic acid. The results indicate that the HSV-induced DNA polymerase is most likely involved in the synthesis of host and HSV DNA in isolated chromatin, even though this chromatin contains small amounts of the host gamma-polymerase in addition to the HSV-induced DNA polymerase. The HSV chromatin contains no detectable levels of DNA polymerases alpha and beta, even though infected cells have normal, or increased, levels of these enzymes.

Centrifugation, Density Gradient↗