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D Perrin

Publications and source records attributed to D Perrin.

141 records · Page 8Linked to original sources
PubMedDate not supplied

Palindromic unit highly repetitive DNA sequences exhibit species specificity within Enterobacteriaceae.

Palindromic units (PU, or REP for repetitive extragenic palindrome) constitute a family of DNA sequences of 40 nucleotides which is highly repeated in the genome of Escherichia coli. We analysed the presence of PU sequences in 99 different bacterial genomes by cross-hybridization. When PU sequences were used as a probe, only DNA from Enterobacteriaceae closely related to E. coli exhibited an appreciable hybridization signal: Shigella sonnei, Shigella boydii, Salmonella enteritica serotype Typhimurium, Citrobacter freundii and Levinea malonatica. Furthermore, these bacteria could be divided into two groups which corresponded to a slight difference in their PU sequence: the E. coli group includes S. sonnei and S. boydii; the S. enteritica serotype Typhimurium group includes C. freundii and L. malonatica.

Blotting, Southern↗
PubMedDate not supplied

The BIME family of bacterial highly repetitive sequences.

Palindromic units (PU or REP) were initially defined as a DNA sequence of 40 nucleotides which is highly repeated in the genome of several enterobacteria and found in clusters of up to six copies. It appears now that PU belong to a larger repeated DNA element, of up to 300 nucleotides, called BIME for bacterial interspersed mosaic element. BIME is a mosaic combination of ten small DNA motifs, including the PU sequence. A central question concerning BIME is to determine whether they play a critical role within the cell. BIME exhibit only limited effects on local gene expression; it seems unlikely that these weak effects alone can account for the high BIME sequence homogeneity. It has recently been shown that DNA gyrase and DNA polymerase I are able to specifically recognize BIME DNA in vitro. These findings suggest that BIME could play a role in the functional organization of the bacterial nucleoid. Hypotheses on their origin and evolution are discussed.

Base Sequence↗
PubMedDate not supplied

Reorganization of alpha-fodrin induced by stimulation in secretory cells.

Spectrin is an ubiquitous protein composed of heterodimers with alpha and beta subunits. It was first described in erythrocyte cell membranes (see ref. 1 for review) and subsequently in brain, intestinal brush borders, kidney, liver and adrenals. Brain spectrin (fodrin) alpha-subunit, responsible for actin binding, has a relative molecular mass (Mr) of 240,000, whereas the beta-subunit, involved in membrane attachment, has an Mr of 235,000 (refs 1, 3, 9-13). The membrane of secretory granules from adrenal chromaffin cells membrane of secretory granules from adrenal chromaffin cells increases the viscosity of F-actin solution, and spectrin-like protein is associated with storage granule and plasma membranes. Here, we report the localization of fodrin in secretory cells using monospecific antibodies against the alpha-subunit of fodrin using indirect immunofluorescence. We find that the alpha-subunit forms an intensely stained continuous ring in the subplasmalemmal region of resting chromaffin cells. On stimulation of the cell with nicotine, high potassium or ionophores in the presence of calcium, fodrin forms patches. This aggregation is inhibited by trifluoperazine, hence the entrance of calcium into cells following cell depolarization seems to be the calmodulin-dependent stimulus initiating patch formation.

Adrenal Medulla↗
PubMedDate not supplied

Anti-alpha-fodrin inhibits secretion from permeabilized chromaffin cells.

Chromaffin cells release catecholamine- and peptide-containing granules by exocytosis, by a mechanism involving movement of secretory granules towards the cell membrane, their apposition to it and the fusion of the granule membrane with the plasma membrane. One of the two subunits of membrane-associated brain spectrin, alpha-fodrin is an actin-binding protein which is found at the periphery of chromaffin cells and may be involved in secretion. Because cultured chromaffin cells can be permeabilized with detergents, giving pores large enough to permit the entry of immunoglobulin molecules, we used permeabilized cells to test the effect of specific antibodies on secretory mechanisms. Incubation of permeabilized cells with polyclonal immunoaffinity-purified monospecific anti-alpha-fodrin antibody or its Fab fragments did not modify basal release but did specifically inhibit Ca2+-induced catecholamine release by exocytosis. Our observations indicate that fodrin and the cytoskeleton participate in the release mechanism.

Adrenal Medulla↗
PubMedDate not supplied

Detection of DNA-strand breaks in cells treated with F 11782, a catalytic inhibitor of topoisomerases I and II.

F 11782, or 2", 3"-bis pentafluorophenoxyacetyl-4',6'-ethylidene-beta-D glucoside of 4'-phosphate-4'-dimethylepipodophyllotoxin 2N-methyl glucamine salt, is a novel fluorinated lipophylic epipodophylloid which has proven cytotoxic activity in vitro and has shown markedly superior antitumour activity in vivo compared to etoposide in various experimental tumour models. However, the precise mechanism(s) of cytotoxicity of F 11782 remains to be defined. In this study, the DNA damaging activity of F 11782 was investigated in GCT27 and C6S cells using, respectively the fluorescence enhancement assay and the technique of DNA alkaline elution. All the results obtained were consistent with induction of DNA damage by F 11782. No evidence of any stabilisation of DNA-topoisomerase cleavable complexes though was obtained with this catalytic inhibitor. Furthermore, such induction of DNA damage has not been reported with other known catalytic topoisomerase inhibitors and so it appears to be unique to F 11782.

Animals↗
PubMedDate not supplied

[Is portacaval anastomosis still valid treatment for portal hypertension in alcoholic cirrhotic patients?].

Mortality and quality of survival after portacaval anastomosis in cirrhotic patients are such that the validity of the operation was investigated during a retrospective study of 242 cases, operation being for hemorrhage and involving emergency or delayed surgery. Operative mortality was higher in emergency cases, but was improved by stricter selection criteria, particularly of pathological features. Cause of death from secondary factors varied during the two years following anastomosis, with perhaps a high frequency of hepatic failure. Recurrence of hemorrhage was a serious complication often related to hepatic insufficiency, while the onset of combined jaundice-edema-ascites (1 out of 4 patients) was frequently the result of continued alcohol abuse. Portacaval encephalopathy (24,4%) did not worsen the vital prognosis, and was severe in only 3 cases. Alcohol intoxication was very frequent in minor forms. Edema of the lower limbs (34,4% of cases), a frequent complication, appeared to result mainly from hemodynamic causes. A return to work was not possible in 20% of patients, but in only 12% was this due to the anastomosis. Portacaval anastomosis would not, therefore, appear to alter survival of patients from complications of cirrhosis. It suppresses the hemorrhagic risk, however, and the course of the disease is then related only to the cirrhosis and to its stability if abstinence is maintained.

Adult↗
PubMedDate not supplied

Tissue iron storage patterns in fetal hydrops associated with congestive heart failure.

To learn whether fetal congestive heart failure causes a characteristic tissue iron storage pattern, we selected 15 neonatal autopsy cases of hydrops fetalis in which both the clinical and gross autopsy findings suggested intrauterine congestive heart failure. The latter appeared to be due to functional causes in 10 (3 nonhemolytic anemia, 4 cardiac dysrhythmia, 3 dilated cardiomyopathy) and was associated with cardiac malformation in 5. We graded the amount of hepatocellular siderosis, reticuloendothelial siderosis, and renal tubular siderosis in Perls-stained microscopic sections of liver, spleen, and kidney and compared the iron storage pattern with that in 15 normally developed neonatal autopsy controls (4 preterm, 11 term) and a further 7 with hemolytic anemia (5 alpha-thalassemia, 2 parvovirus B19 infection). Liver cell siderosis was absent in the three cases with nonhemolytic anemia. It was increased in 11 of the remaining 12 cases, as in hemolytic anemia controls. Among the five cardiac malformation cases, three had proximal renal tubular siderosis (as in hemolytic anemia controls) attributed to turbulent blood flow through the heart. Among the five, hydrops appeared to be due to prenatal closure of the foramen ovale in one and to prenatal constriction of the ductus arteriosus in another. In one of the five, and despite complex malformation of the heart, hydrops appeared to be due to complete heart block. We concluded that, although clinical information and morphologic assessment of the heart were basic to identifying a cardiac cause of fetal hydrops, histologic assessment of the pattern of iron storage helped confirm the pathologic diagnosis. Analysis of the pathologic findings led to a scheme for categorizing cardiogenic fetal hydrops.

Female↗
PubMedDate not supplied

Alveolar capillary dysplasia: lung biopsy diagnosis, nitric oxide responsiveness, and bronchial generation count.

Alveolar capillary dysplasia, a rare cause of neonatal pulmonary hypertension characterized by a developmental abnormality in the pulmonary vasculature, was diagnosed by lung biopsy in a male newborn maintained on nitric oxide therapy for 18 days. Autopsy confirmed the pulmonary vascular defect and demonstrated deficient airspace formation. In addition, a bronchial generation count was low, suggesting that the abnormal lung vascular development in this condition represents a special form of pulmonary hypoplasia that starts in early fetal life.

Biopsy↗