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N Pagratis

Publications and source records attributed to N Pagratis.

8 recordsLinked to original sources
PubMed1996

Comparative study of magnetic resonance angiography, digital subtraction angiography, duplex ultrasound examination with surgical and histological findings of atherosclerotic carotid bifurcation disease.

This study was designed in order to determine the diagnostic accuracy in imaging of the extracranial arteries by using magnetic resonance angiography (MRA), digital subtraction angiography (DSA), B-mode duplex ultrasonic examination (DUE) in comparison with the surgical and histological findings of the specimen removed after endarterectomy. The degree of stenosis of the arterial lumen of the surgical specimen was compared with the imaging findings of MRA, DSA and DUE: a) the degree of agreement of stenosis with histologic findings was found in 89% of cases for MRA, in 93% for DSA and 88% for DUE; b) the correlation of morphology of the plaque showed agreement in 91% of the cases with MRA, in 94% with DSA and 87% with DUE; c) the constitution of the plaque was in agreement with DUE findings in 96% of cases. There is no significant difference between the three methods, as far as the estimation of degree of carotid stenosis and morphology of the atheromatous plaque in the carotid arteries. MRA findings are similar with those of DSA and DUE with a high sensitivity and specificity concerning the constitution of the plaque. The combination of MRA and DUE provides all the necessary information concerning the extracranial segments of the cerebral arteries for the preoperative evaluation of patients with carotid disease.

Angiography, Digital Subtraction↗
PubMed1991

Genome mapping and protein coding region identification using bacteriophage Mu.

Transposons such as bacteriophage Mu provide a means to clone bacterial genes as alternatives to using standard recombinant DNA technologies. A DNA-cloning and gene-expressing system has been developed with a bacteriophage Mu (DNA capacity of 38 kb) vector that combines the Mu transposition capabilities and a specialized promoter from bacteriophage T7. Genes cloned with this vector can be identified by transcription in vivo with T7 RNA polymerase and subsequent host translation. This system, illustrated with the characterization of a 35-kb region of the Escherichia coli K-12 chromosome, is applicable to other Enterobacteriaceae, which are hosts for Mu phage, and is potentially applicable to other bacteria, including Pseudomonas aeruginosa, which have Mu-like phage, and to other organisms for which high-frequency transposons are available.

Bacteriophage mu↗
PubMed1990

Detection of bacteriophage phi 6 minus-strand RNA and novel mRNA isoconformers synthesized in vivo and in vitro, by strand-separating agarose gels.

Two urea-free agarose gel protocols that resolve the six individual strands of bacteriophage phi 6 dsRNA were developed and used to analyze phage RNA synthesis in vivo and in vitro. Citrate gels separate strands of the large and medium chromosomes while Tris-borate-EDTA (TBE) gels resolve the medium and small dsRNA segments. Minus strands migrate faster than plus strands on citrate gels but are retarded on TBE gels. A study of electrophoretic conditions showed that pH affects strand resolution on citrate gels, and that voltage gradient, agarose concentration, and ethidium bromide significantly alter strand migration on TBE gels. Analysis of native phi 6 RNA synthesized in vivo and in vitro showed that the large and medium message RNAs comigrate with the corresponding plus strands of denatured virion dsRNA. The small messenger RNA is exceptional. Native small mRNA was detected as three isoconformers in vivo and in vitro. The isoconformers were converted by heat denaturation to a single RNA species that comigrates with the virion s+ strand. Minus strands labeled in vivo were detected only after heat denaturation. Minus strand synthesis was detected also in heat-denatured samples from in vitro phi 6 nucleocapsid RNA polymerase reactions at pH values suboptimal for transcription.

Autoradiography↗
PubMed1990

Minus-strand RNA synthesis by the segmented double-stranded RNA bacteriophage phi 6 requires continuous protein synthesis.

Bacteriophage phi 6 contains three dsRNA chromosomes. Strand-separating agarose gels were used to study plus- and minus-strand synthesis in vivo and the effect of protein synthesis inhibitors. Analysis of phi 6 RNA synthesis shows low levels of all three dsRNAs and ssRNAs at 10 min, increasing label uptake into all RNAs except the large message from 20 to 60 min, and a greater abundance of medium and small messages than large mRNAs at late times. Isoconformers of the small message are synthesized throughout infection. Northern analysis suggests that large messages made early may persist to direct continuing translation of L-segment-encoded transcription and replication proteins. The time course of phi 6 minus-strand RNA synthesis in vivo, in the absence of background label in host RNAs, is reported for the first time. Label in minus strands is detected only after heat denaturation of RNA samples and appears sequentially in the small, medium, and large strands beginning at 20 min. At both early and late times, chloramphenicol arrests minus-strand synthesis rapidly and all three mRNAs accumulate. The results are consistent with the reovirus asynchronous model for dsRNA viral replication: plus ssRNAs made first are used as templates for minus-strand synthesis. They also indicate that replication protein(s) acts stoichiometrically.

Bacteriophages↗
PubMed1986

Generation of cDNA clones of the bacteriophage phi 6 segmented dsRNA genome: characterization and expression of L segment clones.

Bacteriophage phi 6 has three dsRNA genome segments of about 3.0, 4.0, and 6.4 kbp. More than 90% of the segmented phi 6 dsRNA genome has been cloned as subchromosomal cDNA fragments, generated by reverse transcription of denatured polyadenylated dsRNA, RNA removal, annealing, filling, size fractionation, tailing, and insertion at the PstI site of pBR322. All of the large (L) segment is represented by five overlapping fragments, 98% of the small (S) segment is present in three fragments, and 67% of the medium (M) segment is contained in two fragments. Fragments have been aligned in linear arrays by Southern blot hybridization and restriction enzyme analysis. The orientation of the ordered fragments with respect to genomic RNA and phi 6 transcriptional direction was determined by comparison of terminal DNA sequences with RNA sequences at the genomic ends of phi 6 RNA. Expression of L segment clones using both Escherichia coli minicells and T7 polymerase/promoter vectors indicate that the order of known phi 6 genes on the large chromosome is: 5'--gene 7, gene 2, gene 4, gene 1--3'. cDNA complementation of a ts mutant, ts411, has located this mutation in gene 4.

Bacteriophages↗
PubMedDate not supplied

Is cerebral arteriography necessary for decision making in carotid endarterectomy?

The development of ultrasonic diagnostic imaging technics has recently been a competitive diagnostic method in cerebral arteriography. Many vascular surgeons, based on the high specificity and sensitivity of the ultrasonic imaging technics in carotid artery disease, have been performing carotid endarterectomy without arteriography with satisfactory results. In the last four years we have performed in our Department 62 carotid endarterectomies on 57 patients without using cerebral arteriography. In this paper diagnostic ultrasonic imaging and transcranial Doppler technics are presented and the immediate results of carotid endarterectomy in the above series of patients are reported. From our and other authors' experience it is concluded that carotid endarterectomy in patients with carotid artery disease is a safe procedure. Larger series of patients are needed with a longer follow-up in order that carotid endarterectomy without arteriography be accepted by the medical profession as a safe procedure.

Adult↗