Structure of tandem RNA recognition motifs from polypyrimidine tract binding protein reveals novel features of the RRM fold.

Polypyrimidine tract binding protein (PTB), an RNA binding protein containing four RNA recognition motifs (RRMs), is involved in both pre-mRNA splicing and translation initiation directed by picornaviral internal ribosome entry sites. Sequence comparisons previously indicated that PTB is a non-canonical RRM protein. The solution structure of a PTB fragment containing RRMs 3 and 4 shows that the protein consists of two domains connected by a long, flexible linker. The two domains tumble independently in solution, having no fixed relative orientation. In addition to the betaalphabetabetaalphabeta topology, which is characteristic of RRM domains, the C-terminal extension of PTB RRM-3 incorporates an unanticipated fifth beta-strand, which extends the RNA binding surface. The long, disordered polypeptide connecting beta4 and beta5 in RRM-3 is poised above the RNA binding surface and is likely to contribute to RNA recognition. Mutational analyses show that both RRM-3 and RRM-4 contribute to RNA binding specificity and that, despite its unusual sequence, PTB binds RNA in a manner akin to that of other RRM proteins.

The three-dimensional solution structure of the matrix protein from the type D retrovirus, the Mason-Pfizer monkey virus, and implications for the morphology of retroviral assembly.

The Mason-Pfizer monkey virus (M-PMV) is the prototype of the type D retroviruses. In type B and D retroviruses, the Gag protein pre-assembles before association with the membrane, whereas in type C retroviruses (lentiviruses, BLV/HTLV group) Gag is targeted efficiently to the plasma membrane, where the particle formation occurs. The N-terminal domain of Gag, the matrix protein (MA), plays a critical role in determining this morphogenic difference. We have determined the three-dimensional solution structure of the M-PMV MA by heteronuclear nuclear magnetic resonance. The protein contains four alpha-helices that are structurally similar to the known type C MA structures. This similarity implies possible common assembly units and membrane-binding mechanisms for type C and B/D retroviruses. In addition to this, the interpretation of mutagenesis data has enabled us to identify, for the first time, the structural basis of a putative intracellular targeting motif.

Corrected transposition of the great arteries without associated defects in adult patients: clinical profile and follow up.

OBJECTIVE: To assess the clinical course of adult patients with corrected transposition of the great arteries without associated anomalies. DESIGN: All patients with corrected transposition of the great arteries without associated anomalies were reviewed with complete clinical and echocardiographic assessment. The complications were evaluated in each decade. SETTING: Tertiary centre with a specific unit dealing with "grown-up" adolescent and adult congenital heart disease, designated as a quaternary centre and a general hospital with a referral centre for "grown-up" congenital heart disease. PATIENTS: 18 patients (nine male and nine female) aged 16-61 years followed for 1-30 years (mean 10 years). RESULTS: There were no deaths. Six patients had a worsening ability index during follow up. Complications were: (a) complete heart block in seven, three of whom required pacemaker insertion; (b) significant left atrioventricular valve regurgitation in 50%, appearing only in the third decade (12%), with increasing frequency thereafter. Infective endocarditis was responsible for increasing left atrioventricular valve regurgitation in only one patient; (c) supraventricular arrhythmia appeared in the fifth decade, and occurred in all patients over the age of 60 years. One patient aged 61 had recurrent sustained ventricular tachycardia; and (d) congestive heart failure developed only after 50 years in 66%. One patient had severe left atrioventricular valve regurgitation; the function of the systemic ventricle was only moderately reduced in the other three. Three of the nine women had seven uneventful pregnancies. CONCLUSIONS: Patients with corrected transposition of the great arteries without associated defects may remain undiagnosed until adult life. Symptoms occur rarely before the fourth and fifth decades, when rhythm disturbance, left atrioventricular valve regurgitation, and moderately impaired systemic ventricular function cause congestive cardiac failure. The role of pacemaker insertion or surgery for left atrioventricular valve regurgitation needs further assessment.

Identification, characterization, and analysis of cDNA and genomic sequences encoding two different small heat shock proteins in Hordeum vulgare.

In vitro translation of mRNAs prepared from barley (Hordeum vulgare) seedlings (cv. Onice) exposed at 40 degrees C directed the synthesis of major heat shock proteins (HSPs) with molecular masses of 80-90, 70, 42 and 16-22 kDa. A cDNA library prepared from the 40 degrees C mRNAs and screened by differential hybridization led to the isolation of heat shock specific sequences. One of these (Hv hsp18) was confirmed by hybrid-arrested and hybrid-released translation as encoding for an 18-kDa HSP. The barley hsp18 sequence has an open reading frame encoding a 160 amino acid residue 18-kDa protein that is 63% identical to wheat 16.9-kDa HSP (clone C5-8), 54% identical to soybean (Glycine max) 17.5-kDa HSP, and 49% identical to Arabidopsis thaliana 17.6-kDa HSP. Lower similarities were found with class II plant small HSPs such as soybean 17.9-kDa HSP (27%), Pisum sativum 17.7-kDa HSP (30%), wheat (Triticum aestivum) 17.3-kDa HSP (clone Ta hsp 17.3) (30%), and with animal small HSPs and alpha-crystallins. The Hv hsp18 sequence was used to pick up Hv hsp17 genomic sequence encoding for another class I 17-kDa HSP. By computer analysis of the nucleotide sequence the TATA box, two heat shock promoter elements, a metal-ion response element, and the polyadenylation signals were identified. Barley HSP18 has an additional cysteine-rich region when compared with HSP17 mapping at the carboxy terminal end.

Severe coronary artery disease after radiation therapy of the chest and mediastinum: clinical presentation and treatment.

OBJECTIVE: To define the clinical and angiographic features and the therapeutic problems in patients with coronary artery disease after therapeutic irradiation of the chest. DESIGN: An observational retrospective study. SETTING: The cardiac catheterisation laboratory, university medical school. PATIENTS: 15 subjects (8 men and 7 women, aged 25-56 years, mean 44) examined in the cardiac catheterisation laboratory, who had significant coronary artery disease years after having radiation treatment to the chest and anterior mediastinum. In the early stages of the study angiography was performed because of typical symptoms of ischaemic heart disease. Later on it was performed because of a high index of suspicion in people with signs of extensive radiation heart damage. MAIN OUTCOME MEASURES: Clinical and electrocardiographic evidence of ischaemic heart disease; echocardiographic signs of pericardial, myocardial or valvar involvement; angiographic evidence of coronary arterial stenosis, with special attention to the ostia; haemodynamic and angiographic signs of pericardial, myocardial, and valvar disease. Survival and symptomatic and functional status were ascertained after medical or surgical treatment. RESULTS: The patients were relatively young and had no risk factors. Seven patients had no signs or symptoms of ischaemic heart disease. Ten patients had ostial stenosis, which was associated with extensive involvement of other cardiac structures in nine of them. Seven required surgical treatment for coronary artery disease. Two died, one at surgery and the other one six months later. Five patients had complications associated with irradiation. CONCLUSIONS: Coronary arterial disease can be reasonably ascribed to the effects of chest irradiation when the patients are young and free from risk factors, especially if the obstructions are ostial and there is important damage to other cardiac structures. In patients with damage to other cardiac structures angina and infarction are often absent and coronary angiography seems to be mandatory. Patients often require surgical treatment and postoperative complications are common.

[ Bacterial endocarditis of the pulmonary valve damaged by thoracic radiotherapy (in Hodgkin's disease)]. / Endocardite batterica su valvola polmonare danneggiata da radioterapia toracica (per morbo di Hodgkin).

It is well known that radiation therapy to the anterior mediastinum may induce lesions of all cardiac structures. The pericardium is most frequently involved, but atrioventricular conduction disorders, cardiomyopathy, coronary stenosis may also be produced. Aortic, mitral and tricuspid lesions have been described. However, clinical evidence of pulmonic valve involvement has not been reported. Only at necropsy has fibrotic thickening of the pulmonic cusps occasionally been found. We report a case of infective endocarditis of the pulmonic valve in a 53-year-old patient who had undergone thoracic radiation therapy for Hodgkin's disease 31 years previously. Four years prior to the endocarditis he had also been submitted to myocardial revascularisation for critical lesions of the left main and right coronary ostia, and to aortic valve replacement because of stenosis and insufficiency. At that time, the pulmonic valve was fibrotic on echo examination. It is noteworthy that, of all the cardiac valves, the infective process involved only the pulmonic one, which is seldom the target of an infection. To our knowledge this is the first case of bacterial endocarditis of a heart valve that had been previously damaged by radiation therapy.

[Angiographic findings in arrhythmogenic dysplasia of the right ventricle]. / L'aspetto angiografico della displasia aritmogena del ventricolo destro.

Arrhythmogenic right ventricular dysplasia is characterized by fibrous and adipose replacement of the right ventricular myocardium and recurrent ventricular arrhythmias of left bundle branch block morphologic pattern. Sometimes the diagnosis is difficult because not all the clinical and instrumental findings are present and the separation between arrhythmogenic right ventricular dysplasia and other right ventricular cardiopathies is uncertain. In such cases the angiographic appearance of the right ventricle has been considered the "gold standard". To assess the diagnostic value of right ventricular morphology in identifying arrhythmogenic right ventricular dysplasia, we compared the angiographic findings of 8 patients with arrhythmogenic right ventricular dysplasia, 10 with biventricular dilated cardiomyopathy and 10 with Ebstein's anomaly. The following aspects were considered: deep fissuring of the anterior or inferior wall, outflow tract enlargement, contrast persistence in the right ventricle during the levophase, regional wall motion abnormalities including aneurysmal formations and tricuspid regurgitation. Aneurysmal formations of the right ventricle were found only in arrhythmogenic right ventricular dysplasia whereas the other angiographic findings were common to all the above mentioned diseases. Right ventricular angiography is an important adjunct to the clinical and instrumental diagnosis of arrhythmogenic right ventricular dysplasia, but most of its angiographic features are common to other diseases which cause right ventricular dilatation.

[Incidence and significance of ventricular arrhythmia after surgical correction of Fallot's tetralogy]. / Frequenza e significato delle aritmie ventricolari dopo correzione chirurgica della tetralogia di Fallot.

Patients may die suddenly after surgical repair of tetralogy of Fallot. Ventricular arrhythmias (VA) have been considered the possible cause of sudden death in such patients by many Authors. We evaluated the incidence and severity of VA in a group of 65 patients (25 females and 40 males) after surgical repair of tetralogy of Fallot. The age at the time of follow-up varied between 8 and 47 years. We divided our population into 4 groups (A, B, C, D) according to the surgical results (poor and good) and to the age of total correction (less than 12, greater than 12 years). We tested the presence and severity of VA in the different groups of patients and we found a significant difference in the incidence of VA between patients who underwent surgery before and after the age of 12 years (p = 0.0083). The surgical result did not show a significant relation with VA (p = 0.47). Among the patients submitted to surgical repair in the adult age, however, more serious VA are present in those with poor surgical result, and both our cases of sudden death occurred in this kind of patient. We speculate that postoperative ventricular arrhythmias are related to right ventricular function, which in turn appears to be worse in patients who underwent surgical correction at a later age. At last only perspective trials will be able to assess the significance of VA and their relationship with sudden death in this kind of patient.

Results of total correction of tetralogy of Fallot performed in adults.

Today, total correction of tetralogy of Fallot is rarely performed in adults. In a 10-year period, 40 patients aged 20 to 67 years underwent intracardiac repair in our institution. Twenty-eight of them had had a palliative procedure 11 to 30 years earlier. Preoperatively, 23 patients were in New York Heart Association (NYHA) Functional Class II, 14 were in Class III, and 3 were in Class IV. Operative mortality was 2.5% (1/40). Follow-up ranged from 1 year to 11 years (average, 3 years). One patient died of a noncardiac cause 4 years after operation. Residual cardiac defects were observed in 4 patients. Postoperatively, 30 patients were in NYHA Functional Class I, 8 were in Class II, and 1 was in Class III. Major ventricular arrhythmias were recorded in 7 (35%) of 20 patients. Radionuclide angiography demonstrated impaired right ventricular function in 8 patients. Left ventricular impairment was present in 2. Total correction of tetralogy of Fallot can be performed safely in adults with low mortality and good functional improvement. The incidence of residual cardiac defects is low. The long-term importance of impaired ventricular function and arrhythmias remains to be ascertained.

[2 cases of arrhythmogenic dysplasia of the right ventricle of familial occurrence]. / A proposito di due casi di displasia aritmogena del ventricolo destro ad incidenza familiare.

Cases of familial arrhythmogenic right ventricular dysplasia (ARVD) have been reported by many authors, and a genetic mechanism of transmission has been hypothesized. Both autosomal dominant and autosomal recessive mechanism of inheritance were suggest. We present a father and a daughter affected by arrhythmogenic right ventricular dysplasia, belonging to a family with many cases of sudden death. Both of them presented with an episode of ventricular tachycardia with left bundle branch block. The clinical diagnosis was made according to electrocardiographic, echocardiographic, angionuclear and hemodynamic criteria of ARVD. The familia analysis suggest an autosomal dominant mechanism of transmission.