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Biomedical subjects

J Paul

Publications and source records attributed to J Paul.

At least 199 records · Page 11Linked to original sources
PubMed1987

Long-term evaluation of five biomaterials for angioplastic enlargement of the pulmonary artery in a young dog model.

In 45 young dogs an enlargement angioplasty of the left pulmonary artery was performed using patches made from one of three autologous materials (jugular vein, unmodified pericardium, and glycerolized pericardium) or from two heterologous materials (lyophilized human dura mater and modified bovine carotid artery). Catheterization and angiographic studies performed 5 to 6 months after the operation showed that all patched vessels had remained patent, except in three dogs which had received heterologous implants. The animals were killed 5-24 months after operation (mean weight increase: 84%), and the implants were studied by optical microscopy and morphometry, scanning and transmission electron microscopy, and indirect immunofluorescence with antidog Factor VIII rabbit antiserum. The two heterologous tissues exhibited limited biocompatibility, as estimated from 10 criteria obtained at histologic studies. Conversely, all three autologous biomaterials were characterized by infiltration of noninflammatory cells, near-complete endothelialization, and neosynthesis of structural proteins; infectious foci were very rare or absent. These results suggest that autologous tissues, although deendothelialized at the time of implantation, constitute the most suitable material for patch angioplasty, as far as endothelial triggering, cellularity and resistance to infection are concerned.

Animals↗
PubMed1987

Our experience with extended wear contact lenses.

The follow up of the patients was short and there may be failures later because of frequent lens loss or deposits on the lenses. In this study the failures which occurred did so within the first few weeks. It is probable that we can advise our patients that Extended Wear Contact Lenses are worn successfully by 70% of the patients with gratifying results.

Adolescent↗
PubMed1986

Rat coagulation factor V purification and production of the monospecific antiserum.

An original method was applied to purify rat factor V. The final preparation had a sp. act. of 45 U/ml for a 2500-fold purification with a yield of 43%. The final product is partially activated since it is 4.7-fold activable by RVV-VAE vs 6.3 in plasma. It can explain the presence of some of the four slightly stained additional bands found in SDS-electrophoresis. Finally, results of the purification suggest that rat factor V is a 338,000 single chain glycoprotein with a strong molecular asymmetry. A factor V deficient fraction was produced and used to adsorb an anti-factor V antiserum. This adsorbed antiserum was found monospecific against purified rat factor V.

Animals↗
PubMed1985

The vibrational bands of carbon monoxide bound to hemes or metal surfaces.

Infrared spectra of imidazole carbonyl complexes of 2,4-substituted hemes are presented. An increased CO stretch frequency is accompanied by a lowered FeC vibrational energy. Hartree-Fock-Slater electron structure calculations discern pi and sigma contributions to the observed shifts of vibrational energies. We conclude that an enhanced electron availability manifests itself as a lowered ferric/ferrous reduction potential, increased filling of the 2 pi orbital of liganded CO which in turn reduces nu CO and increases nu Fec, and increased basicity of the liganded CO. Analogies between CO liganded to heme and CO adsorbed onto metal surfaces are discussed.

Carbon Monoxide↗
PubMed1985

Spin and electron distributions in heme-cyanide models and hemeproteins.

Proton NMR spectra of low-spin Fe(III) cyanoprotoheme as prosthetic group in a number of proteins are presented. The diagonally positioned 1-, 5- and 3-, 8-methyl groups obey shifts proportional to the Fe(III)/(II) reduction potential Em7, which indicates a pseudo-contact interaction. The correlation with Em7 is understandable if one postulates an enhanced rhombic distortion, dominating the Fe-methyl dipolar interactions. Hartree-Fock-Slater quantum chemical calculations show no significant changes of spin density as a function of the Fe-L5 distance, except at the iron atom and predominantly in the 3dxz and 3dyz orbitals. 4p orbitals, on the other hand, uphold most of the changes of electron density. We also observe a principal difference in the amino acid sequences in the heme-accommodating pocket of oxygen carriers and two-electron transmitters.

Cyanides↗
PubMed1985

Immunolocalization of factor V in adult and fetal rat liver.

Immunolocalization of the factor V was performed in adult and fetal rat liver by means of an indirect peroxidase labelling. This could be done owing to the production in our laboratory of a mono-specific antiserum anti rat factor V. In all the cases (perfused and non-perfused adult liver and fetal one) the observation of the sections has revealed an intense circular or granular labelling into all the hepatocytes whatever was their localization in the hepatic lobule. Hepatic endothelial cells seemed to be negative for factor V and this aspect of our results was discussed.

Animals↗
PubMed1985

Tissue specific transcription of the human epsilon-globin gene following transfection into the embryonic erythroid cell line K562.

We have introduced a plasmid containing the human epsilon-globin gene either stably or transiently into a number of erythroid or non-erythroid cell lines, and analysed the accuracy and efficiency of transcription. In non-erythroid cells (or in mouse erythroleukaemia (MEL) cells in which adult but not embryonic globin genes are expressed) transcription of the epsilon-globin gene occurs mainly from a site 200 bp upstream of the major cap site (the -200 cap site). In the human K562 cell line, in which the endogenous epsilon-globin gene is transcribed at high levels, transcription initiation from the introduced gene occurs mainly from the major cap site. Transcriptional activity of the epsilon-globin gene introduced into K562 cell is quantitatively similar to that of the endogenous gene. This suggests the presence (or absence) in K562 cells of factor(s) which activate (or repress) the epsilon-globin gene in a tissue specific manner.

Cell Line↗
PubMed1985

In vitro study of the inhibition of coagulation induced by different radiocontrast molecules.

The anticoagulant activity of seven intravascular radiocontrast molecules (RCM) was evaluated in different in vitro systems using citrated human plasma. Each RCM was tested in a concentration range of 5 to 50 mM. The thrombin time and the reptilase time showed a dose-dependent lengthening of fibrinoformation, the recording of fibrinoformation exhibited a significant delay of fibrin monomer generation and polymerization although the amplitude of the fibrinoformation was not decreased. The interfering effect with fibrin clot formation impairs also global coagulation tests and monospecific coagulation tests using fibrinoformation as the final step of the assay, but a possible interaction between RCM and some specific coagulation factors cannot be excluded. RCM potentiated the anti-thrombin action of heparin but the inhibition or delay of fibrinoformation is not related to an antithrombinic effect of contrast media. The thrombin amidolytic activity is not modified by RCM but the generation of FpA is delayed and decreased. The ultrastructure of the fibrin clot is not altered at the end of the polymerization.

Adult↗
PubMed1985

Chromatin structure of genes during the cell cycle.

K562 cells were separated by centrifugal elutriation into 5 fractions each of which had a unique distribution of cells at different phases of the cell cycle. A study of DNAseI sensitivity of the epsilon- and gamma-globin genes, which are expressed in these cells, and the lambda light chain immunoglobulin gene, which is not expressed, in nuclei from each of the 5 fractions was undertaken. There was no detectable difference in the arrangement of DNAseI-hypersensitive sites (DHS) in chromatin of each of the three genes in the different fractions.

Cell Cycle↗
PubMed1985

Experimental DMNA induced hepatic necrosis: early course of haemostatic disorders in the rat.

The course of haemostasis defects was investigated in dimethylnitrosamine (DMNA) acute liver necrosis. Before 18 hr there was no evidence of disseminated intravascular coagulation (DIC) nor of abnormal fibrinolysis. At 12 hr the level of the vitamin-K-dependent factors (factors II, VII, IX and X) was reduced to 25-63% of control. Factors V and VIII:C levels decreased to about 10 and 20% by 12 hr. Factor V was the only molecule which decreased significantly by 6 hr. The rapid decrease of these proteins might be related to an early parenchymal functional impairment attested by early structural lesions observed in the endoplasmic reticulum and nucleus. The isolated decrease of factor V in the absence of any significant change in serum transaminase (SGOT and SGPT) levels is proposed, at least in the rat, as an early criterion of hepatic failure.

Alanine Transaminase↗
PubMed1985

Distant sequences which regulate globin genes.

Besides the major cap site, transcription of the human epsilon-globin gene initiates at several upstream sites, the furthest 4.5 kb away. The upstream initiation sites occur in regions of hypersensitivity to DNaseI. There is also a very prominent DNaseI hypersensitive site 6.5 kb upstream which corresponds to an unusual nucleotide sequence. Upstream promoters, particularly one 200 bp upstream can be regulated independently of the major cap site. This site behaves as if it were a unidirectional enhancer. A fragment upstream of the mouse beta-globin promoter acts as a negative regulator in cis; it contains a long stretch of alternating purine and pyrimidine bases. The significance of upstream regulatory sequences adjacent to globin genes is discussed.

Base Sequence↗
PubMed1984

The chromatin structure of the human epsilon globin gene: nuclease hypersensitive sites correlate with multiple initiation sites of transcription.

We have mapped sites in chromatin flanking the epsilon-globin gene in the K562 cell which are hypersensitive to digestion with DNAseI, micrococcal nuclease and S1 nuclease. Many of those in the 5' flanking region correspond to minor upstream transcriptional starts. However, one prominent site occurs upstream of the boundary of transcription; it maps to a region with an unusual DNA sequence. In baby hamster kidney cells stably transformed with recombinant DNA containing the human epsilon-globin gene and in Cos 7 cells transiently transfected with DNA containing the epsilon-globin gene, hypersensitive sites can be demonstrated.

Animals↗
PubMed1984

Alternative sites of transcription initiation upstream of the canonical cap site in human gamma-globin and beta-globin genes.

Using S1 mapping and primer extension analysis, we have identified a number of human kappa-globin and beta-globin 5' RNA termini originating in the 200 bp upstream of the canonical mRNA cap sites. Upstream initiation sites have previously been reported for the human epsilon-globin gene (4,5) and the present work indicates that this is a general feature of the human beta-type globin genes. We have attempted to identify features common to such sites between the three genes. One site 170 bp upstream of the major beta-globin cap site and a site 1400 bp upstream of the major epsilon-globin cap site are located near putative PolIII promoter sequences and may therefore be transcribed by this enzyme. Alternative initiation sites located 200 bp and 50-100 bp upstream of the epsilon-globin and kappa-globin cap sites respectively are located within S1 hypersensitive regions of chromatin.

Base Composition↗
PubMed1984

Transcription in vivo of an Alu family member upstream from the human epsilon-globin gene.

The more distal Alu repeat flanking the epsilon-globin gene is transcribed in K562 cells to generate transcripts 350-400 nucleotides in length. Initiation occurs at the start of the repeat, upstream of a putative PolIII control signal. These transcripts originate from the strand which does not code epsilon-globin and are oriented in the opposite direction from the gene. They are non-polyadenylated, nucleus-confined and are only detectable in association with expression of the epsilon-globin gene.

Cell Line↗
PubMed1984

A negative regulatory sequence near the mouse beta-maj globin gene associated with a region of potential Z-DNA.

The possible regulatory role of DNA sequences situated 5' to the beta-maj globin gene was investigated by two types of assay. First, a long term transformation assay was used to measure the efficiency of transformation of TK- mouse (LATK-) and hamster (BHKTK-) fibroblast cells with DNA molecules made by covalently linking mouse and human DNA fragments to the herpes simplex virus (HSV-1) thymidine kinase (tk) gene in the plasmid pTK1. When the promoter regions from the mouse beta-maj globin or the human epsilon-globin genes are substituted for the viral promoter in the tk gene transformation occurs with 10-20% of the efficiency of the original plasmid. A fragment (H1), containing sequences between 344 and 1413 bp upstream from the mouse beta-maj globin cap site, almost completely abolishes transformation when inserted next to hybrid tk genes containing the mouse beta-globin or human epsilon-globin promoter but has no effect on the intact tk gene. The effect can be demonstrated with the H1 fragment in either orientation relative to the tk gene. Secondly, in transient expression assays the H1 fragment strongly inhibits transcription when covalently linked to the tk gene under control of either globin promoter, but not when linked to the tk gene with its own promoter. The H1 fragment contains 53 bp of purine-pyrimidine alternation (ACAT)n as part of a larger region potentially capable of adopting a Z-DNA conformation.

Animals↗
PubMed1984

Oncogenes.

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Animals↗
PubMed1984

Heterozygous female carriers of the marker-X-chromosome: IQ estimation and replication status of fra(X)(q).

The IQ levels of 18 female carriers with the marker X chromosome were evaluated, and cytogenetic studies after BrdU incorporation were performed. A highly significant correlation between mental capacity and replication pattern of the X chromosomes could be demonstrated. Heterozygous females with normal intelligence showed a clear tendency to carry the fragile site at the late replicating X chromosome, while other female carriers with lower intelligence or mental impairment expressed their fragile site mainly with the early replicating X chromosome. This observation could be interpreted as an expression of Lyonisation .

Adolescent↗