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Biomedical subjects

J M Peltier

Publications and source records attributed to J M Peltier.

At least 19 recordsLinked to original sources
PubMed1999

[Ischemic pseudo-normalization of T waves and ST segment].

The development of acute myocardial ischaemia in a territory with baseline repolarization abnormalities can be reflected by transient pseudo-normalisation of the T wave and/or ST segment. These repolarization abnormalities can occur spontaneously, during a stress test or during of an isoproterenol test. Clinicians should be familiar with these unusual electrocardiographic changes of acute ischaemia, which require appropriate surveillance and treatment.

Acute Disease↗
PubMed1998

[Late recurrence of a large post-infarction left ventricular pseudo-aneurysm. A case report].

Left ventricular pseudo-aneurysm is a neo-cavity characterised by the presence of a narrow neck and a wall consisting of fibrous tissue and thrombotic debris without any muscular cells. The diagnosis must be made as soon as possible by non-invasive methods (echocardiography, CT scan, MRI ...) or by angiography before early surgical treatment, in view of the high risk of secondary rupture. The authors report this original case of a post-infarction left ventricular pseudoaneurysm which recurred five years after initial surgical cure.

Adult↗
PubMed1996

Structural characterization of U*-1915 in domain IV from Escherichia coli 23S ribosomal RNA as 3-methylpseudouridine.

Mass spectrometry-based methods have been used to study post-transcriptional modification in the 1900-1974 nt segment of domain IV in 23S rRNA of Escherichia coli, a region which interacts with domain V in forming the three- dimensional structure of the peptidyl transferase center within the ribosome. A nucleoside constituent of M r 258 (U*)which occurs at position 1915, within the highly modified oligonucleotide sequence 1911-psiAACU*Apsi-1917, was characterized as 3-methylpseudouridine (m3psi). The assignment was confirmed by chemical synthesis of m3psi and comparison with the natural nucleoside by liquid chromatography-mass spectrometry. 3-Methylpseudouridine is previously unknown in nature and is the only known derivative of the common modified nucleoside pseudouridine thus far found in bacterial rRNA.

Base Sequence↗
PubMed1995

Implications of a functional large ribosomal RNA with only three modified nucleotides.

The sequence and structure of the peptidyl transferase region of large subunit ribosomal RNA is highly conserved and specific modified nucleotides could be important structural or functional elements in the catalytic center responsible for peptide bond formation. In fact, it has not been possible to reconstitute active E coli 50S subunits from in vitro transcripts of 23S rRNA and total 50S proteins. It is significant therefore, that the PET56 gene of yeast encodes an essential ribose methyltransferase that specifically modifies a universally conserved nucleotide, G2270, in the peptidyl transferase center of the mitochondrial large ribosomal RNA (21S). Since the loss of this modification in yeast mitochondrial 21S rRNA severely affects the assembly of 54S subunits, it is likely that the analogous 2'-O-methylguanosine at position 2251 (Gm2251) in E coli 23S rRNA is also required for the assembly of 50S subunits. Gm could be a critical structural determinant for the correct folding of the rRNA, the binding of one or more ribosomal proteins, or the interaction of the rRNA with tRNA. Previous work has shown that the mitochondrial large rRNAs are minimally modified relative to the E coli and eukaryotic cytoplasmic rRNAs. By direct chemical analysis using combined high performance liquid chromatography-mass spectrometry, the modification status of the yeast mitochondrial rRNAs was reexamined, revealing the presence of Gm, Um and pseudouridine (psi) in 21S rRNA. The Um was mapped to nucleotide 2791, which corresponds to the ribose methylated and universally conserved U2552 in E coli 23S rRNA, and the psi has been recently mapped to position 2819, which corresponds to psi 2580 in E coli 23S rRNA. The retention of Um and psi nucleotides in the peptidyl transferase center of the otherwise minimally modified mitochondrial rRNAs suggests that these modifications, like Gm2270, might be essential for ribosome assembly or function or both.

Base Sequence↗
PubMed1994

Mixed Cu+ and Zn2+ coordination in the DNA-binding domain of the AMT1 transcription factor from Candida glabrata.

AMT1 is the transcription factor required for Cu-induced expression of metallothionein genes in the yeast Candida glabrata. The copper-binding, DNA-binding domain of AMT1 has been purified after expression of an AMT1 synthetic gene in bacteria and was confirmed as active in a gel shift assay. The Cu-activated AMT1 was shown to contain a Cu(+)-thiolate tetracopper center and a single Zn2+ site. AMT1 is purified as a Cu-Zn protein from bacterial cultures grown in the presence of CuSO4. Chemical analysis suggested that 4.2 +/- 0.2 and 1.2 +/- 0.2 molar equiv copper and zinc ions bound, respectively. Electrospray mass spectrometry was used to verify that a uniform species was present with 4 Cu+ ions and 1 Zn2+ ion bound per AMT1 molecule. Cu+ binding to form a tetracopper center occurs cooperatively as shown by electrospray MS of apoAMT1 samples reconstituted with increasing equivalency of Cu+. Copper-thiolate coordination was indicated by Cu-S charge-transfer transitions in the ultraviolet, luminescence typical of Cu-thiolate clusters and EXAFS. Analysis of the EXAFS of CuZnAMT1 revealed predominantly trigonal Cu+ coordination and the presence of a polycopper cluster by virtue of a short Cu-Cu distance of 2.7 A. Zn K-edge EXAFS of Cu4Zn1AMT1 and electronic spectroscopy of AMT1 with Co2+ substituted for the single Zn2+ ion are consistent with tetrahedral Zn2+ coordination with thiolate ligands. The Cu-activated AMT1 exhibited a conformation distinct from that of metal-free AMT1 as shown by circular dichroism. DNA binding by AMT1 was dependent on the tetracopper center but was independent of occupancy of the Zn2+ site. This is the first report of a single, uniform tetracopper center in a metal-activated transcription factor.

Amino Acid Sequence↗
PubMed1993

[False traumatic aneurysm of the internal mammary artery caused by a stab wound. Apropos of a case].

The authors report the case of embolism by a false aneurysm of the internal mammary artery: a 57 years old woman with no previous medical history was admitted to the emergency unit with a kitchen knife stuck in the 3rd left intercostal space. After withdrawing the knife, in the operating theatre, radiological controls revealed a blurred opacity in the left antero-superior mediastinum. The patient signed her own discharge from hospital against medical advice on the 7th day. She was readmitted 10 months later for left retrosternal chest pains. Chest X ray demonstrated a rounded opacity in the antero-superior mediastinum. Computed tomography with injection of contrast confirmed the vascular nature of the opacity. Arteriography in the aortic arch confirmed the diagnosis of false aneurysm of the left internal mammary artery. Selective angiography of the internal mammary artery was undertaken and the aneurysm was embolised with coils. The clinical outcome was immediately improved with relief from the chest pains.

Aneurysm, False↗
PubMed1991

Determination of the glycosidic linkage in peracetylated disaccharides comprised of D-glucopyranose units by use of desorption electron-ionization mass spectrometry.

An oxonium ion at m/z317 is present in the desorption electron ionization and ammonia desorption chemical ionization mass spectra of peracetylated disaccharides, comprised of glucopyranose units linked (1-->2), (1-->3), (1-->4) and (1-->6), but is absent in the spectra of the (1-->1)-linked isomer. The ion at m/z317, which is derived from the reducing moiety, has an O-formyl group at the position of linkage to the non-reducing moiety, and O-acetyl groups at each of the remaining positions. The isomeric monoformyl, triacetyl oxonium ions (at m/z317), derived from the (1-->2)-, (1-->3)-, (1-->4)- and (1-->6)-linked disaccharides, give distinctly different mass-analysed ion kinetic energy spectra, thereby enabling the linkage position to be assigned unambiguously.

Acetylation↗
PubMed1988

[Congenital aneurysm of the coronary arteries. Apropos of 2 cases].

Two cases of aneurysm of the coronary arteries were diagnosed by coronary angiography in the course of a myocardial infarction. The first aneurysm was located at the level of the left coronary trunk in a 32 year-old woman; it was complicated with a massive anterior infarction which led to a heart transplant in the following months. The second aneurysm was located on the right coronary artery in an 18 year-old man; the inferior infarction was rudimentary and the subsequent course was quite favorable. Congenital aneurysm of the coronary arteries is a rare anomaly, often localized on the left coronary trunk and almost always diagnosed in young patients following myocardial infarction.

Adolescent↗
PubMed1984

[Posttraumatic infarction with a surgically treated floating thrombus of the left ventricle. Apropos of a case].

Forty-two days after severe thoracic trauma which had led to thrombosis of the left renal artery and to nephrectomy, a 22 year old patient developed anterior wall infarction. Echocardiography and coronary and left ventricular angiography showed distal occlusion of the left anterior descending artery and the presence of a large, mobile thrombus at the left ventricular apex. The thrombus was removed surgically without any complications but a small thrombus adherent to the ventricular scar was observed postoperatively. After a discussion on the different possible physiopathological mechanisms, the authors conclude that the patient probably suffered primary myocardial contusion which led to secondary occlusion of the LAD artery, late myocardial infarction and extension of the initial intraventricular thrombus. This case illustrates the value of two-dimensional echocardiography in the detection and follow-up of ventricular thrombosis.

Adult↗