Histological study of the proximal and distal segments of the embryonic outflow tract and great arteries

The normal development of the ventricular outlets and proximal region of the great arteries is a controversial subject. It is known that the conus, truncus arteriosus (truncus), and aortic sac participate; however, there are some doubts as to the actual prospective fate of the truncus. Some authors propose that it gives origin to the proximal region of the great arteries and that the myocardial cells of its wall become smooth muscle. Nevertheless, others think that the truncus only forms the arterial valve apparatus and that therefore the myocardial cells transform into fibroblasts. As a first approach to beginning to elucidate which process occurs, the aim of this article was to study the histological changes in the wall of these components of the developing heart in chick embryos whose hearts had been labeled at the truncoconal boundary at stage 22HH, tracing the changes up to stage 36HH. Also, the histological constitution of the wall of the pulmonary arterial trunk and its valve apparatus were studied in the posthatching and adult hearts of chickens and rats. The conus and truncus walls were always encircled by a myocardial sleeve from the outset of their development. Between stages 26HH to 28HH, the truncal myocardial cells adjacent to the mesenchymal tissue of the ridges began to lose cell-to-cell contacts and invaded the extracellular matrix. At stage 24HH, the aortic sac began to project into the pericardial cavity and became divided into two channels by the aortic-pulmonary septum at stage 26HH. The wall of the aortic sac is mostly constituted by a compact mesenchymal tissue. Initially, it does not have smooth muscle but this starts to appear at stage 30HH. The insertion ring of the valves, a broad structure, was formed by mesenchymal tissue. Both structures were always covered by a myocardial sleeve. The leaflets developed from the truncal ridges, the segment immediately proximal to the aortic sac. Our results indicate that the proximal region of the pulmonary and aortic arteries do not originate from the truncus arteriosus; rather, we found that they take origin from the aortic sac. Thus, our findings agree with the proposal that the myocardial cells of the external sleeve of the truncus become fibroblastic and suggest that the insertion ring of the arterial valves has a dual origin: fibroblasts produced by truncal myocardial transdiferentiation and the mesenchymal tissue of the proximal region of the truncal ridges, while the leaflets have their origin from the truncal ridges. We discuss the fact that, because the truncus arteriosus does not give origin to the trunks of the aortic and pulmonary arteries, it may be necessary to modify terminology. Based on our results, together with the new findings obtained by in vivo labeling, immunostaining, a chimeric approach, and ultrastructural studies, we propose a developmental model that correlates the fate of the conus, truncus, and aortic sac with the normal morphogenesis of the ventricular outlet tracts and the trunks of the great arteries. (c) 2005 Wiley-Liss, Inc.     

Bacteremia caused by an undescribed species of Janibacter

A yellow-pigmented rod- to coccoid-shaped coryneform microorganism was isolated from the blood of a patient with acute myeloid leukemia. It was identified by 16S rRNA gene sequencing as a previously undescribed species of Janibacter. The isolate was susceptible to penicillins, aminoglycosides, fluoroquinolones, and glycopeptides.     

Effects of overexpansion on stents' recoil, symmetry/asymmetry, and neointimal hyperplasia in aortas of hypercholesterolemic rabbits.

BACKGROUND: It is not known whether overexpansion modifies stent recoil, symmetric distribution of struts, and neointimal hyperplasia. OBJECTIVES: The objectives were (a) to evaluate whether stent overexpansion modifies the geometric configuration of the stent in the arterial wall, (b) to determine the relationship between overexpansion and stent recoil, and (c) to evaluate the relationship between the distribution of struts and neointimal hyperplasia. METHODS: Twenty tubular stainless steel 316L stents (3.0 and 3.5 mm in diameter) were implanted at 20 and 10 atm, respectively, in the abdominal aorta of New Zealand rabbits fed a hypercholesterolemic diet (1% cholesterol). Sham operations were also performed in seven animals. Eight weeks after implantation or sham operation, an intravascular ultrasound (IVUS) study was performed to measure stent recoil and aid in stent classification (symmetric or asymmetric) according to strut distribution. The degree of injury and neointimal hyperplasia were also evaluated in hematoxylin-eosin stained sections. RESULTS: The symmetry/asymmetry of stents assessed by IVUS, as well as the neointimal hyperplasia, was similar in both groups. Stent recoil was significantly greater in the 3.0-mm stent (overexpanded) group (0.28+/-0.02 mm), as compared with stent recoil in the 3.5-mm stent group (0.10+/-0.01 mm, P<.05). The neointimal hyperplasia in histological slices, independent of the implant technique, was predominantly in zones with higher strut concentration as compared with zones with fewer struts. CONCLUSIONS: Stent overexpansion enhanced stent recoil and did not modify symmetric and asymmetric strut distribution. Neointimal hyperplasia was not modified by the implant technique. Interestingly, significant hyperplasia was observed in locations with greater strut concentration, independent of overexpansion.     

Bruton tyrosine kinase gene mutations in Argentina

The block in differentiation from pro-B to pre-B cells results in a selective defect in the humoral immune response characteristic of human X-linked agammaglobulinemia (XLA). Mutations of Bruton tyrosine kinase (BTK) gene have been identified as the cause of XLA. Mutation detection is the most reliable method for making a definitive diagnosis, except when clinical and laboratory findings are distinctive and coupled with history of X-linked inheritance. To provide a definitive diagnosis to 40 families incorporated in the Argentinian Primary Immunodeficiencies Registry we analysed the BTK gene by SSCP analysis as screening method for XLA, followed by direct sequencing. The molecular defect was localized in 45 patients from 34 unrelated families. From the 34 independent mutations identified, 16 were previously undescribed, 31 were unique mutations, 22 were exonic single nucleotide changes (16 missense and 6 nonsense) and four intronic mutations. Because five families had clinical, immunological and inheritance data sufficient for a definitive diagnosis, our study allowed 37 patients from 29 families previously categorized probable/ possible XLA, have now definitive diagnosis leading to appropriate genetic counseling.     

Phenotype-genotype characterization of 10 families with severe a subunit factor XIII deficiency

Factor XIII (FXIII) deficiency is a very rare severe autosomal bleeding disorder with a frequency of 1:2,000,000 in the general population and only a few patients have been genetically characterized so far. We report a phenotype-genotype characterization of 10 unrelated Iranian patients. Two FXIII (transglutaminase) activity assays showed no FXIII activity, except a conserved residual activity in patients receiving prophylactic substitution treatment. FXIII antigen concentrations measured by two immunoassays were comparable. Genotype characterization identified four novel mutations (2 missense and 2 small deletions) and two previously reported missense mutations in the FXIII A subunit gene (F13A). Molecular modeling was carried out to reveal the structural consequences of the missense mutations, that caused the replacement of an arginine residue involved in the formation of structurally important extensive hydrogen-bonded network. The replacements [c.320G>A (p.Arg77His) in the beta-sandwich, c.868C>T (p.Arg260Cys), c.869G>A (p.Arg260His) and c.1236G>T (p.Arg382Ser) in the core domain] resulted in the loss or impairment of such H-bonded network. Energy decomposition analysis demonstrated that this situation leads to the instability and perhaps to the incorrect folding of the A subunit, that would explain the development of severe FXIII deficiency.     

Interphase fluorescence in situ hybridization analysis of del(11)(q23) and del(17)(p13) in chronic lymphocytic leukemia. a study of 40 early-onset patients

Although B-cell chronic lymphocytic leukemia (B-CLL) is the most common form of leukemia in Western countries, little is known about its underlying molecular abnormalities and their prognostic significance, particularly for use in early therapeutic interventions in young patients. As TP53 tumor suppressor gene abnormalities and 11q23 deletions are reported to be prognostically adverse in hematologic malignancies, we used interphase fluorescence in situ hybridization to analyze their incidence and prognostic significance in young B-CLL patients. Bone marrow samples from 40 untreated B-CLL patients at diagnosis were studied using five yeast artificial chromosome clones from the 11q23.1 approximately q23.3 chromosomal region and a probe specific for the 17p13.1 locus. Twenty-three patients (58%) carried 11q deletions. Interestingly, 16 of 17 patients (94%) who showed early disease progression exhibited this chromosomal abnormality, suggesting that 11q deletions may help to identify more aggressive disease in early stage patients. In contrast, monoallelic TP53 deletions were found in all of the patients. The TP53 and 11q deletions were only present in a proportion of the clonal B-cells, which suggests that they are secondary events in B-CLL.     

Molecular characterization of a novel pattern recognition protein from nonspecific cytotoxic cells: sequence analysis, phylogenetic comparisons and anti-microbial activity of a recombinant homologue

Nonspecific cytotoxic cells (NCC) are the first identified and most extensively studied killer cell population in teleosts. NCC kill a wide variety of target cells including tumor cells, virally transformed cells and protozoan parasites. The present study identified a novel evolutionarily conserved oligodeoxynucleotide (ODN) binding membrane protein expressed by channel catfish (Ictalurus punctatus) NCC. Peptide fingerprinting analysis of the ODN binding protein (referred to as NCC cationic anti-microbial protein-1/ncamp-1) identified a peptide that was used to design degenerate primers. A catfish NCC cDNA library was used as template with these primers and the PCR-amplified product was sequenced. The translated sequence contained 203 amino acids (molecular mass of 22,064.63 Da) with characteristic lysine rich regions and a pI=pH 10.75. Sequence comparisons of this protein indicated similarity to zebrafish (51.2%) histone family member 1-X and (to a lesser extent) to trout H1. A search of EST databases confirmed that ncamp-1 is also expressed in various tissues of channel catfish as well as zebrafish. Inspection for signature repeats in ncamp-1 and comparisons with histone-like peptides from different species indicated the presence of multiple lysine based motifs composed of AKKA or PKK repeats. The novel protein was cloned, expressed in E. coli and the recombinant was used to generate rabbit anti-serum. The recombinant ncamp-1 bound GpC and CpG ODNs and was detected with homologous anti-ncamp-1 polyclonal antibodies. Western blots of NCC membranes using anti-ncamp-1 serum detected a 29 kDa protein. Binding competition experiments demonstrated that anti-ncamp-1 antibodies and GpC bound to the same protein on NCC. Two different truncated forms of ncamp-1 as well as the full-length recombinant protein exhibited anti-microbial activity. The present study demonstrated the expression by NCC of a new membrane protein that may participate in the recognition of bacterial DNA and as such participate in innate anti-microbial immune responses in teleosts.     

Technical basis for magnetic resonance images

The spin-echo procedure is the basic technique in a magnetic resonance (MR) study (the magnetization vector is flipped by 90° onto the ortogonal plane to the main magnetic field). Very soon after the MR procedure was developed, it was pointed out how important it is to achieve the needed contrast with shorter repetition times (TRs) to reduce the imaging time. Recently, fast imaging techniques have been introduced (partial flip angles, short TRs, and the lack of 180° radiofrequency pulses to refocus the spins are their main characteristics; the spins are refocused by the application of a gradient reversal technique). These techniques are particularly needed in pediatric neuroradiology, where the examination time must be as short as possible. At present, partial flip-angle techniques are almost completely replacing the conventional spin-echo procedure, but the variations in flip angle could result in a change in contrast. For these reasons, conventional spin-echo techniques may still be useful in a routine MR study.Presented at the 11th Meeting of the European Society for Paediatric Neurosurgery, Naples 1988