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R Blasco

Publications and source records attributed to R Blasco.

At least 55 records · Page 3Linked to original sources
PubMed1996

Molecular and Regulatory Properties of the Nitrate Reducing Systems of Rhodobacter

Phototrophic bacteria of the genus Rhodobacter possess several forms of nitrate reductase including assimilatory and dissimilatory enzymes. Assimilatory nitrate reductase from Rhodobacter capsulatus E1F1 is cytoplasmic, it uses NADH as the physiological electron donor and reduced viologens as artificial electron donors, and it is coupled to an ammonium-producing nitrite reductase. Nitrate reductase induction requires a high C/N balance and the presence of nitrate, nitrite, or nitroarenes. A periplasmic 47-kDa protein facilitates nitrate uptake, thus increasing nitrate reductase activity. Two types of dissimilatory nitrate reductases have been found in strains from Rhodobacter sphaeroides. One of them is coupled to a complete denitrifying pathway, and the other is a periplasmic protein whose physiological role seems to be the dissipation of excess reducing power, thus improving photoanaerobic growth. Periplasmic nitrate reductase does not use NADH as the physiological electron donor and is a 100-kDa heterodimeric hemoprotein that receives electrons through an electron transport chain spanning the plasma membrane. This nitrate reductase is regulated neither by the intracellular C/N balance nor by O2 pressure. The enzyme also exhibits chlorate reductase activity, and both reaction products, nitrite and chlorite, are released almost stoichiometrically into the medium; this accounts for the high resistance to chlorate or nitrite exhibited by this bacterium. Nitrate reductases from both strains seem to be coded by genes located on megaplasmids.

Journal Article↗
PubMed1996

A vaccinia virus core protein, p39, is membrane associated.

We describe herein the characterization of p39, the product of the A4L gene of vaccinia virus. By immunolabelling of thawed cryosections from infected HeLa cells, we show that this protein is initially located in the central region, or viroplasm, of the viral factories, as well as in the immature virions, with very small amounts of labelling observed on the surrounding membranes. The localization of p39 changes dramatically during the transition of the immature virion to the intracellular mature virus (IMV), coincident with the appearance of the core structure in the center of the IMV, with p39 located between this core and the surrounding membranes. Complementary biochemical data, such as partitioning into the Triton X-114 detergent phase and stripping of the viral membranes with Nonidet P-40 and dithiothreitol, suggest that p39 is associated with the innermost of the two membranes surrounding the core. Sodium carbonate treatment also indicates that p39 is associated with membranes, even at the early stages of viral assembly. However, following in vitro translation of p39 in the presence of microsomal membranes, we failed to detect any association of the independently expressed protein with membranes. We also failed to detect any posttranslational acylation of p39 with myristate or palmitate, suggesting that p39 does not achieve its membrane association through lipid anchors. Therefore, p39 is most likely membrane associated through an interaction with an integral membrane protein(s) present in the innermost of the two membranes surrounding the IMV. These data, together with our recent data showing that p39 colocalizes with the spike-like protrusions on the IMV core (N. Roos, M. Cyrklaff, S. Cudmore, R. Blasco, J. Krijnse-Locker, and G. Griffiths, EMBO J. 15:2343-2355, 1996), suggest that p39 may form part of this spike and that it possibly functions as a matrix-like linker protein between the core and the innermost of the two membranes surrounding the IMV.

Cell Membrane↗
PubMed1996

[PSA and PSAD study in patients with renal dysfunction].

This study analyzes the changes in serum and urinary PSA values in 28 subjects; 13 with creatinine clearance under 75 ml/mn and 15 with creatinine clearance over 75 ml/mn. Both groups were compared for prostate size, measured by transrectal ultrasound, prostate weight, serum PSA (SPSA), 24h urine PSA (PSAO), PSA clearance (PSACl), serum creatinine (SCr), creatinine clearance (CrCl), PSA density (PSAD), PSA/creatinine ratio (PSA/Cr) and PSACl/CrCl ratio. Mean values of SPSA and PSAO were 4.5 +/- 0.8 and 222 +/- 29.7 ng/ml respectively, values for SCr, CrCl and PSACl averaging 1.62 +/- 0.2 mgr/dl, 71.6 +/- 6.5 ml/mn and 150.5 +/) 32.9 ml/mn. Median prostate size was 32.6 +/- 3.9 cc, with weights of 40.3 +/- 4.9 g and mean PSA density (PSAD) 0.13 +/- 0.02. The results of the homogeneity study showed that there are no significant differences between both groups with regard to the variables considered in the study. SPSA values were higher in patients with CrCl < 75; 3.4 vs 5.7, but not significantly. There are no significant differences between PSAO and PSACl values for both groups, even though PSAO levels were higher in patients with CrCl < 75 ml/min (p = 0.1). PSAD values for patients with CrCl > 75 ml/mn were lower than those for patients with CrCl < 75 ml/mn; 0.09 vs 0.17 (p = 0.08). In the entire sample, PSAD levels showed correlation with SPSA and PSA/Cr values; R = 0.63 (P = 0.0003) and r = 0.5 (p = 0.009) respectively. Also, they were significantly but inversely correlated with PSACl levels; r = - 0.5 (p = 0.006) and PSACl/CrCl; r = - 0.048 (p = 0.01). No correlation was seen between PSAD values and the following parameters; PSAO (p = 0.7), SCr (p = 0.5) and CrCl (p = 0.27). When the group of patients with CrCl < 75 ml/mn is considered, PSAD values are correlated exclusively with PSACl values; r = - 0.69 (p = 0.008) and PSACl/CrCl; r = 0.68 (p = 0.009). Our data appear to indicate that there is a certain relationship between PSAD and the renal function although the physiopathological mechanism responsible for that is unknown. Nevertheless, considering the sample size, more comprehensive studies will be necessary to obtain more convincing results.

Aged↗
PubMed1995

From xenobiotic to antibiotic, formation of protoanemonin from 4-chlorocatechol by enzymes of the 3-oxoadipate pathway.

Chloroaromatics, a major class of industrial pollutants, may be oxidatively metabolized to chlorocatechols by soil and water microorganisms that have evolved catabolic activities toward these xenobiotics. We show here that 4-chlorocatechol can be further transformed by enzymes of the ubiquitous 3-oxoadipate pathway. However, whereas chloromuconate cycloisomerases catalyze the dechlorination of 3-chloro-cis,cis-muconate to form cis-dienelactone, muconate cycloisomerases catalyze a novel reaction, i.e. the dechlorination and concomitant decarboxylation to form 4-methylenebut-2-en-4-olide (protoanemonin), an ordinarily plant-derived antibiotic that is toxic to microorganisms.

Adipates↗
PubMed1995

Selection of recombinant vaccinia viruses on the basis of plaque formation.

We developed a procedure for isolation of recombinant vaccinia viruses (re-VV) based solely on plaque formation, without a requirement for specific cell lines, selective medium or special staining. The system consists of two components: (i) a mutant non-plaque-forming VV and (ii) a plasmid vector that, through homologous recombination, can simultaneously introduce a foreign gene and repair mutation in the VV genome. The mutant VV contains a deletion of the vp37 gene, encoding a 37-kDa protein component of the viral outer envelope that is required for efficient viral spread on cell monolayers. The plasmid vector contains a functional vp37, a strong synthetic VV early/late promoter, unique restriction sites for gene insertion, and flanking segments of VV DNA for homologous recombination. Following infection and transfection of cells with the mutant VV and plasmid vector, respectively, re-VV are identified and isolated by their ability to form plaques. To evaluate the system, a re-VV that expresses the gene encoding influenza virus hemagglutinin (HA) was isolated simply by picking visible plaques.

Amino Acid Sequence↗
PubMed1995

[Cytologic and biochemical component in 203 bronchoalveolar lavages. Reference values].

The bronchoalveolar lavage (BAL) is considered a basic technique as a diagnostic aid in Pneumology. However, one of the main problems faced by the clinician is the lack of standardization of the technique. This has been resolved through the drafting of international standards. The other problem is the lack of what might be called a "reference" BAL. In order to establish a reference BAL, we analyzed 203 BAL divided in two groups: a control group and a pathologic group, make up by extrinsic asthma, intrinsic asthma, pulmonary infections, diffuse interstitial pneumopathies, bronchopulmonary tumors and chronic bronchitis. We have studied both the cytologic and the biochemical component of the BAL. Among the biochemical markers, we have considered; carcinoembrionary antigen (CEA), tissular polypeptidic antigen (TPA), neuronal specific enolase (NSE), ferritin (FER), calcitonin (CT), ACTH, histamin (HIS) and prostaglandin (PGE2). In order to establish the reference values, we have used the modified Baye's theorema. The BAL that we obtained was the following: volume 20 ml, cells 35 x 10(5) cells/ml, macrophages 77%, lymphocytes 22%, neutrophils 4%, eosinophils 2%, CEA 14 ng/mg, TPA 84 U/g PT, NSE 5 ng/mg PT, FER 42 ng/mg PT, CT 15 pg/mg PT, ACTH 51 pg/mg PT, HIS 1.22 ng/mg PT, PGE2 35 pg/mg PT.

Adolescent↗
PubMed1994

The clinical value of neuron-specific enolase as a tumor marker in bronchoalveolar lavage.

BACKGROUND: Neuron-specific enolase (NSE) is used in the staging and monitoring of responses to therapy and the detection of recurrences in lung cancer. The diagnostic value of NSE has been under discussion. This may be because NSE usually has been studied in the sera of patients with bronchogenic carcinoma and not in the bronchoalveolar lavage (BAL). METHODS: The NSE levels in the BAL of three groups--control subjects, patients with chronic bronchitis, and patients with tumors--were analyzed. The fluid obtained was centrifuged. The NSE was analyzed in the supernatant of the BAL (NSE, Pharmacia, Columbia, MD). Its concentrations were calculated in relation to milligrams of total protein. RESULTS: A significant difference was noted in the level of NSE in the BAL of the tumor group compared with those of the other two groups. No differences were observed between the other two groups or between healthy smokers and nonsmokers. No correlation was found with the histologic type of pulmonary carcinoma and NSE levels in BAL. The NSE levels were higher in the lavages of patients with primary pulmonary carcinomas than in those with metastases. CONCLUSIONS: Neuron-specific enolase could be of aid in the early diagnosis of solitary pulmonary nodules and lung cancer. More studies would be required to identify a correlation between NSE levels in BAL and those in serum, or between NSE levels in BAL and tumor size and location and disease stage of lung cancer.

Adenocarcinoma↗
PubMed1994

Molecular cloning and expression of collagenase-3, a novel human matrix metalloproteinase produced by breast carcinomas.

A cDNA coding for a new human matrix metalloproteinase (MMP) has been cloned from a cDNA library derived from a breast tumor. The isolated cDNA contains an open reading frame coding for a polypeptide of 471 amino acids. The predicted protein sequence displays extensive similarity to the previously known MMPs and presents all the structural features characteristic of the members of this protein family, including the well conserved PRCGXPD motif, involved in the latency of the enzyme and the zinc-binding domain (HEXGHXXXXXHS). In addition, this novel human MMP contains in its amino acid sequence several residues specific to the collagenase subfamily (Tyr-214, Asp-235, and Gly-237) and lacks the 9-residue insertion present in the stromelysins. According to these structural characteristics, the MMP described herein has been tentatively called collagenase-3, since it represents the third member of this subfamily, composed at present of fibroblast and neutrophil collagenases. The collagenase-3 cDNA was expressed in a vaccinia virus system, and the recombinant protein was able to degrade fibrillar collagens, providing support to the hypothesis that the isolated cDNA codes for an authentic collagenase. Northern blot analysis of RNA from normal and pathological tissues demonstrated the existence in breast tumors of three different mRNA species, which seem to be the result of the utilization of different polyadenylation sites present in the 3'-noncoding region of the gene. By contrast, no collagenase-3 mRNA was detected either by Northern blot or RNA polymerase chain reaction analysis with RNA from other human tissues, including normal breast, mammary fibroadenomas, liver, placenta, ovary, uterus, prostate, and parotid gland. On the basis of the increased expression of collagenase-3 in breast carcinomas and the absence of detectable expression in normal tissues, a possible role for this metalloproteinase in the tumoral process is proposed.

Amino Acid Sequence↗
PubMed1994

Nucleotide sequence and variability of the inverted terminal repetitions of African swine fever virus DNA.

African Swine fever virus (ASFV) genome is a large (170-190 kb) double-stranded DNA molecule with structural features similar to those of Poxviruses. Prominent among those features are the presence of a hairpin loop structure at the end of the DNA molecule and terminal-inverted repeats (TIR). The TIRs have been previously demonstrated by electron microscopy and cross-hybridization of terminal restriction fragments. We have determined the sequence of both left and right DNA ends from the BA71V virus strain. The TIR is composed of 2134 bp and was identical at both genome ends. As much as 82% of the TIR sequence is made up of short (27-35 bp) sequences repeated within the TIR, in five different sets of repeats. The central portion of the TIR is occupied by a 34-bp sequence which is repeated in tandem 33 times. Length differences were found within TIRs of virus clones isolated from a single infected animal. The ASFV TIR resembles in structure the TIR of the related Poxviruses.

African Swine Fever Virus↗
PubMed1994

[Subdural hemorrhage of aneurysmal origin].

Although most subdural hematomas are considered to be venous in origin, they may also be of arterial origin. When subdural bleeding is due to the rupture of an intracranial aneurysm, most commonly at the middle cerebral or internal carotid arteries, the amount of subdural blood is usually small and of no clinical importance. We describe two patients with subdural hematomas secondary to rupture of an intracranial aneurysm, who needed prompt surgical treatment. The first patient had a left internal carotid artery aneurysm at the origin of the ophthalmic artery. In the second patient the aneurysm was at the anterior communicating artery and rebled into the subdural space directly through a right intraparenchymatous frontobasal hematoma. The most probable mechanism of subdural bleeding in our two patients was the existence of adhesions between the aneurysm and the arachnoid due to previous minor hemorrhages. The indication of cerebral angiography in a patient with subdural hematoma is based mainly upon the existence of meningeal signs, the presence of blood in more than one intracranial compartment or the rapid progression of bleeding.

Aged↗
PubMed1993

Characterization of a nitrophenol reductase from the phototrophic bacterium Rhodobacter capsulatus E1F1.

The phototrophic bacterium Rhodobacter capsulatus E1F1 photoreduced 2,4-dinitrophenol to 2-amino-4-nitrophenol by a nitrophenol reductase activity which was induced in the presence of nitrophenols and was repressed in ammonium-grown cells. The enzyme was located in the cytosol, required NAD(P)H as an electron donor, and used several nitrophenol derivatives as alternative substrates. The nitrophenol reductase was purified to electrophoretic homogeneity by a simple method. The enzyme was composed of two 27-kDa subunits, was inhibited by metal chelators, mercurial compounds, and Cu2+, and contained flavin mononucleotide and possibly nonheme iron as prosthetic groups. Purified enzyme also exhibited NAD(P)H diaphorase activity which used tetrazolium salt as an electron acceptor.

2,4-Dinitrophenol↗
PubMed1993

Dissociation of progeny vaccinia virus from the cell membrane is regulated by a viral envelope glycoprotein: effect of a point mutation in the lectin homology domain of the A34R gene.

Vaccinia virus strains vary considerably in the amounts of extracellular enveloped virus (EEV) that they release from infected cells. The IHD-J strain produces up to 40 times more EEV than does the related WR strain and consequently generates elongated comet-shaped virus plaques instead of sharply defined round ones in susceptible monolayer cells under liquid medium. The difference in EEV formation is due to the retention of enveloped WR virions on the cell surface (R. Blasco and B. Moss, J. Virol. 66:4170-4179, 1992). By using WR and IHD-J DNA fragments for marker transfer and analyzing the progeny virus by the comet formation assay, we determined that gene A34R and at least one other gene regulate the release of cell-associated virions. Replacement of the A34R gene of WR with the corresponding gene from IHD-J increased the amount of EEV produced by 10-fold and conferred the ability to form distinctive comet-shaped plaques. Gene A34R encodes an EEV-specific glycoprotein with homology to C-type animal lectins (S.A. Duncan and G.L. Smith, J. Virol. 66:1610-1621, 1992). The nucleotide sequences of the A34R genes of WR and IHD-J strains differed in six positions, of which four were silent. One of the codon mutations (Lys-151-->Glu), which is located in the putative carbohydrate recognition domain, was sufficient to transfer a comet-forming phenotype to WR virus. These data indicate that the A34R-encoded glycoprotein is involved, through its lectin homology domain, in the retention of progeny virus on the surface of parental cells and raise the possibility that the protein also has a role in virus attachment to uninfected cells.

Animals↗
PubMed1992

Expansion of the mammalian 3 beta-hydroxysteroid dehydrogenase/plant dihydroflavonol reductase superfamily to include a bacterial cholesterol dehydrogenase, a bacterial UDP-galactose-4-epimerase, and open reading frames in vaccinia virus and fish lymphocystis disease virus.

Mammalian 3 beta-hydroxysteroid dehydrogenase and plant dihydroflavonol reductases are descended from a common ancestor. Here we present evidence that Nocardia cholesterol dehydrogenase, E. coli UDP-galactose-4 epimerase, and open reading frames in vaccinia virus and fish lymphocystis disease virus are homologous to 3 beta-hydroxysteroid dehydrogenase and dihydroflavonol reductase. Analysis of a multiple alignment of these sequences indicates that viral ORFs are most closely related to the mammalian 3 beta-hydroxysteroid dehydrogenases. The ancestral protein of this superfamily is likely to be one that metabolized sugar nucleotides. The sequence similarity between 3 beta-hydroxysteroid dehydrogenase and the viral ORFs is sufficient to suggest that these ORFs have an activity that is similar to 3 beta-hydroxysteroid dehydrogenase or cholesterol dehydrogenase, although the putative substrates are not yet known.

3-Hydroxysteroid Dehydrogenases↗
PubMed1992

A gene homologous to topoisomerase II in African swine fever virus.

A putative topoisomerase II gene of African swine fever virus was mapped using a degenerate oligonucleotide probe derived from a region highly conserved in type II topoisomerases. The gene is located within EcoRI fragments P and H of the African swine fever virus genome. Sequencing of this region has revealed a long open reading frame, designated P1192R, encoding a protein of 1192 amino acids, with a predicted molecular weight of 135,543. Open reading frame P1192R is transcribed late after infection into a 4.6-kb RNA. The deduced amino acid sequence of this open reading frame shares significant similarity with topoisomerase II sequences from different sources, with percentages of identity between 23 and 29%. The evolutionary relationships among the topoisomerase II sequences of ASF virus, eukaryotes and prokaryotes were analyzed and a phylogenetic tree was established. The tree indicates that the ASF virus topoisomerase II gene was present in the virus genome before protozoa, yeasts, and metazoa diverged.

African Swine Fever Virus↗