Focal Atrial Tachycardia Originating from the Donor Superior Vena Cava after Bicaval Orthotopic Heart Transplantation

An 11‐year‐old boy, who underwent bicaval orthotopic heart transplantation for idiopathic dilated cardiomyopathy, had a focal atrial tachycardia originating from the donor superior vena cava. The pathogenesis of this tachycardia may be related to transplant rejection or transplant vasculopathy. Radiofrequency catheter ablation can eliminate this unique tachycardia and result in hemodynamic improvement. (PACE 2010; e68–e71)     

THE SPECTRUM OF 67-kD LAMININ RECEPTOR EXPRESSION IN BREAST CARCINOMA PROGRESSION

Laminin is a glycoprotein of the basement membrane (BM), involved in a variety of normal and pathological cellular events including tumour invasion and metastasis. Cells bind laminin through different types of receptor. The 67-kD laminin receptor (67LR) is a cell-surface protein which binds laminin with high affinity. 67LR expression has been shown to increase in neoplastic cells, compared with normal tissues, and 67LR seems to play an important role during the first steps of neoplastic progression. In this study, 67LR expression was analysed during the morphological phases of breast cancer progression from normal tissue to invasive carcinoma. A total of 506 formalin-fixed, paraffin-embedded normal breast structures and lesions were stained by immunohistochemistry using the MLuC5 monoclonal antibody, which is specific for 67LR. The results show that in normal breast and in any kind of breast lesion, myoepithelial and endothelial cells express 67LR. While 67LR is not seen in the epithelium of normal breast, cysts, adenosis, and benign tumours, it is expressed in the epithelial cells of several hyperplasias and carcinomas in situ, both ductal and lobular, as well as in all invasive carcinomas. The 67LR-positive cell subpopulation expands from hyperplastic lesions to invasive carcinoma, suggesting that 67LR could be related to the induction and progression of breast cancer. © 1997 John Wiley & Sons, Ltd.     

A CD strategy for the study of polypeptide folding/unfolding

The circular dichroism spectrum of the 20-residue immunogenic peptide from the foot-and-mouth disease virus (VP1; 141-160 of serotype A, subtype 12) was solvent- and temperature-dependent. Careful solvent titration revealed two isodichroic points and plateaux consistent with stepwise unfolding of specific stable conformations. Variable temperature studies in cryogenic solvents and urea perturbation were consistent with the existence of three conformational moieties, the left-handed extended helix, the a-helix, and the α-helix. The number of residues in each helix was confirmed by CD spectral simulations. The strategy described here can be used to determine the components of a conformational equilibrium and their statistical weights, to study peptide folding and unfolding and to determine the bioactive conformation(s) of linear peptides. The conclusions were supported by 2D-NMR studies. A new mechanism for the stabilization of left-handed extended helices and destabilization of a-helices by urea is proposed. The structure of the peptide as resolved by CD spectroscopy is of particular significance since the conformation of this antigenic sequence in situ has so far not been solved by X-ray crystallography.     

Hemodynamics of Idiopathic Paroxysmal Atrial Fibrillation

The hemodynamics of induced atrial fibrillation (AF) was investigated in 15 patients (ages 58 ± 11 years) with paroxysmal AF presenting without organic heart disease or hypertension. A hemodynamic study was performed both during sinus rhythm and after the induction of AF. The mean heart rate increased from 73 ± 11 to 128 ± 18 beats/min (P < 0.001) after AF. Systolic and mean aortic pressures did not significantly change, and diastolic aortic pressure increased (78 ± 11 vs 89 ± 12 mmHg, P < 0.01). Left ventricular enddiastolic pressure decreased during AF (9 ± 3 vs 6 ± 2.6 mmHg, P < 0.005), whereas mean pulmonary wedge pressure increased (8 ± 2 vs 12 ± 4 mmHg, P < 0.001). Systolic pulmonary arterial pressure did not show significant variations, and there was a slight but statistically significant increase in the diastolic and mean pulmonary arterial pressures (P < 0.01). The right ventricular end-diastolic pressure decreased during AF (5.6 ± 2 vs 3.8 ± 2 mmHg, P < 0.01 j, whereas mean right atrial pressure showed a trend toward an increase. Stroke volume markedly decreased (P < 0.001) while the cardiac index did not significantly change. Systemic vascular resistance, pulmonary arteriolar resistance, and the arteriovenous O₂ difference showed no significant variations after the induction of AF. These results suggest that in subjects without organic heart disease, paroxysmal AF is well tolerated hemodynamicaily, and the rise in the atrial pressures during AF is not related to an increase in the ventricular end-diastolic pressure.     

Synthesis and conformational studies on peptides corresponding to a putative autophosphorylation site of abl TPK*

The transforming gene of Abelson murine leukaemia virus (v-abl) codes for a membrane-associated tyrosine-specific protein kinase (abl TPK). Analysis of the v-abl gene has shown that both the fibroblast-transforming and tyrosine-protein kinase activities reside within a minimal region encoding a protein of 43 kDa (p43^v-abl), which represents the most active, isolated form of this enzyme. Since the cellular substrates for p43 ^v-abl are yet to be identified, we synthesized by classical solution methods the octapeptide H-Gly-Asp-Thr-Tyr-Thr-Ala-His-Ala-OH, corresponding to the structural sequence of the main putative autophosphorylation site (Tyr 515) of the abl TPK, as well as some of its analogs modified in positions -2, -1, + 1 and + 3. The synthetic peptides were tested as substrates for the p43^v-abl. The kinetic data obtained indicate that the rates of their phosphorylation vary considerably depending on the sequence of the peptide, as expected. As a rule, no significant increment of the efficiency results from each substitution in the parent sequence. While the replacement of the two charged residues, namely Asp-2 and His-7, with neutral Ala is well tolerated, the substitution with amino acids bearing opposite charges is detrimental. The correlation between secondary structure of our synthetic octapeptides and their substrate recognition by p43^v-abl was studied using CD and fluorescence spectroscopy in 5 mM Tris, in 98% TFE/Tris and in 30 mM SDS solutions. The comparison of the spectroscopic data with the kinetic parameters does not confirm a close relationship between the conformational properties of these peptides and their enzymatic role.     

Antigenic and Cytochemical Characterization of Cells Adhering to Intrauterine Contraceptive Devices

ABSTRACT: Eighteen copper intrauterine devices (IUDs), removed after 25 months of use, were examined to evaluate cells adhering to them (IAC). By means of monoclonal antibodies, the antigenic phenotype of IAC was studied, along with some IAC cytochemical properties. Sixty percent of IAC were identified as granulocytes based on morphological, cytochemical, and antigenic characteristics. A small proportion of IAC were shaped like large foreign-body macrophages, with multiple picnotic nuclei, and diffused alpha naphtyl acetate esterase (ANAE) activity. Some IAC identified as macrophages from a morphological view point also showed dipeptidil-diaminopeptidase IV (DAPIV) reactivity, previously described only in T-helper lymphocytes. Most IAC identified as macrophages reacted with the monoclonal antibodies OKM1 and HLA-DR, and showed ANAE activity in the form of small multiple granules. The hypothesis that IUD-adhering macrophages with an ANAE +, DAPIV+, OKM1 +, and HLA-DR + phenotype could play a role in the inactivation of spermatozoa can be proposed.     

Moderate alcohol intake and risk of myocardial infarction among non-smokers

We have conducted a hospital-based case-control study on 157patients with newly diagnosed myocardial infarction and 157hospital controls. All were men, 35–69 years old and non-smokersor ex-smokers of at least 6 months. A clearcut inverse dose-responserelationship was found between alcohol intake (chiefly red wine)and risk of Ml (odds ratios were 0.69, 0.43 and 0.42, for thosedrinking 1–30, 30–90 and >90 drinks per month,compared to <1). Adjustment by coronary risk factors in logistic-regressionmodels increased the strength of the association with alcohol.Protection was somewhat stronger than in studies conducted incountries where the consumption of beer or liquors is heavierthan that of wine. The protective effect might be due to theantioxidant properties of phenolic substances contained in redwine.