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Biomedical subjects

R Frank

Publications and source records attributed to R Frank.

At least 379 records · Page 21Linked to original sources
PubMed1988

Structural requirements for the synthesis of tRNATrp from Dictyostelium discoideum in yeast.

Dictyostelium tRNA genes can generally be expressed in vivo in yeast. Among tested Dictyostelium tRNA genes a tRNATrp gene containing a 13 bp intron is transcribed with particularly poor apparent efficiency and the intron is not removed. Elimination of the intron from the gene increases the amount of transcription products significantly. Splicing can only occur if minimal base-pairing of the anticodon with intron sequences is possible. Accumulation of tRNA gene transcripts decreases with the inability of intron splicing. Products of neither amber (UAG) nor opal (UGA) suppressor variants of the tRNATrp gene from Dictyostelium are able to suppress corresponding non-sense mutations in defined structural yeast genes. This also holds true for suppressor tRNA gene variants with precisely deleted intron regions.

Dictyostelium↗
PubMed1988

Identification and catheter ablation of a zone of slow conduction in the reentrant circuit of ventricular tachycardia in humans.

Three patients who had incessant ventricular tachycardia and in whom a zone of slow conduction was identified are presented. Each patient's tachycardia was refractory to multiple antiarrhythmic drugs and was being treated with amiodarone at the time of the electrophysiologic study. The ventricular tachycardia cycle length was 500 to 580 ms. In Patients 1 and 2, a single site at the posterolateral wall or low septum in the left ventricle was identified at which overdrive pacing during ventricular tachycardia resulted in ventricular capture with a stimulus to QRS interval of 280 to 400 ms and with little or no change in the configuration of the QRS complexes during pacing as compared with during ventricular tachycardia. In Patient 3, the same phenomenon was observed at two areas in the left ventricle: at the inferior wall, overdrive pacing during ventricular tachycardia resulted in a stimulus to QRS interval of 440 to 470 ms, whereas at the posterolateral wall, the stimulus to QRS interval was 320 to 360 ms. Transcatheter shocks of 100 to 240 J delivered at the pacing sites have been successful in preventing recurrences of ventricular tachycardia over a follow-up period of 10 to 11 months. These observations may be explained by the pacing site being located within a reentrant circuit in a zone of slow conduction bounded by inexcitable tissue between the pacing site and the exit site of the reentrant circuit. In Patient 3, the variable stimulus to QRS intervals are explained by variable proximity of the pacing sites within the slow conduction zone to the exit site of the reentrant circuit.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Techniques and methods for catheter endocardial fulguration.

Fulguration is a new and promising technique for the treatment of cardiac arrhythmias. This paper discusses the methods and equipment used at Jean Rostand Hospital for invasive experimental research related to fulguration. The importance of catheter testing and selection is demonstrated. The most important features of the measurement techniques for both His bundle and ventricular tachycardia recordings are described. The main components of the protocols for fulguration and early post-operative surveillance are reported. The ODAM Fulgucor is used, augmented by the incorporation of additional pieces of equipment to allow monitoring of current and voltage curves. An electromechanical relay allows for automatic switching from the recording amplifier to the energy source. The video system used includes recording of the image of the last fluoroscopic event with a character generator and an electronic pointer superimposed (when necessary). Computer programs for appropriate timing of predominant events have been developed.

Arrhythmias, Cardiac↗
PubMed1988

Efficacy and safety of low doses of beta-blocker agents combined with amiodarone in refractory ventricular tachycardia.

Twenty patients aged 55 +/- 16 years with 40 chronic ventricular tachycardias (VT) refractory to 4.6 +/- 1.9 antiarrhythmic drugs, used alone or in combination, were managed by low doses of beta-blocker agents combined with oral amiodarone (Am), either after loading (1.2 g for 7 days, n: 5) or reloading (1.2 g for 4 days, n: 15) of Am. All patients proved refractory to Am alone. Seven VT were also refractory to endocardial catheter fulguration in six patients. Thirteen patients had coronary artery disease, three had arrhythmogenic right ventricular dysplasia, two had dilated cardiomyopathy, one had valvular disease, and one had no structural heart disease. Ten patients had an EF less than 30%. Ten patients were in NYHA functional class three. VT was permanent in three patients, daily in three, weekly in seven, paroxysmal in seven. In 11 patients, VT occurred both at day and night. In 11 patients, decrease of the sinus cycle preceeded VT. Oral administration of a daily low dose of a beta blocker agent (acebutolol 100 mg, betaxolol 5-10 mg, metoprolol 50 mg, nadolol 20-40 mg, pindolol 2.5 mg, propanolol 30 mg, sotalol 80-160 mg, terta-tolol 2.5 mg) combined with 400 mg/day of Am suppressed VT episodes in all patients. None presented heart failure or collapse. The mean reduction of the heart rate was 15% (65 to 55/min). At discharge, exercise ECG (n: 14) induced non sustained VT in two patients. At programmed electrical stimulation (PES) (n: 15), VT was no longer inducible in 4 patients, was slower, well-tolerated in nine patients, and remained inducible at the same rate in only two patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1988

Localization of reaction center and B800-850 antenna pigment proteins in membranes of Rhodobacter sphaeroides.

The localization of the N- and C-terminal regions of pigment-binding polypeptides of the bacterial photosynthetic apparatus of Rhodobacter sphaeroides was investigated by proteinase K treatment of chromatophore and spheroplast-derived vesicles and amino acid sequence determination. Under conditions of proteinase K treatment of chromatophores, which left the in vivo absorption spectrum and the membrane intact, 15 and 46 amino acyl residues from the N-terminal regions of the L and M subunits, respectively, of the reaction center polypeptides were removed. The N termini are therefore exposed on the cytoplasmic surface of the membrane. The C-terminal domain of the light-harvesting B800-850 alpha and B870 alpha polypeptides was found to be exposed on the periplasmic surface of the membrane. A total of 9 and 13 amino acyl residues were cleaved from the B800-850 alpha and B870 alpha polypeptides, respectively, when spheroplasts were treated with proteinase K. The N-terminal regions of the alpha polypeptides were not digested in either membrane preparation and were apparently protected from proteolytic attack. Seven N-terminal amino acyl residues of the B800-850 beta polypeptide were removed after the digestion of chromatophores. C-terminal residues were not removed after the digestion of chromatophores or spheroplasts. The C termini seem to be protected from protease attack by interaction with the membrane. Therefore, the N-terminal regions of the beta polypeptides are exposed on the cytoplasmic membrane surface. The C termini of the beta polypeptides are believed to point to the periplasmic space.

Amino Acid Sequence↗
PubMed1988

[Long-term course of conduction disorders in 97 patients with an HV interval superior or equal to 70 milliseconds].

The natural history of disorders of conduction is imperfectly known. The presence of an HV interval of 70 milliseconds or more, which is regarded as pathological, usually results in pacemaker implantation. In this study the course of symptoms and disorders of conduction was investigated in 97 patients with an HV interval of 70 ms or more, and therefore equipped with a pacemaker, followed up for a mean period of 26.5 +/- 19.5 months. Among these 97 patients, 65 had presented with one or several syncopes, 14 had experienced feelings of faintness and 18 were asymptomatic. Among patients with symptoms, these totally disappeared in 63 and became milder in the remaining 12 patients. Complete and permanent AV block was observed in 11 patients. The actuarial incidence of complete permanent AV block was about 5 p. 100 per annum until 4 years. The only predictive parameter for such a course was the occurrence of a second degree type 2 or a third degree paroxysmal block prior to pacemaker implantation (significantly associated with the absence of symptoms).

Adult↗
PubMed1988

[Rhythm and conduction disorders immediately after ventricular fulguration].

UNLABELLED: Forty-four patients with ventricular tachycardias (VT) refractory to medical treatment underwent 73 sessions of endocavitary electrode catheter ablation. The clinical series included 16 cases of post-infarction VT, 14 cases of arrhythmogenic right ventricular dysplasia, 6 cases of dilated cardiomyopathy, 6 cases of idiopathic VT, 1 case of sequela of myocarditis and 1 case of VT consecutive to surgical repair of a congenital cardiopathy. Cardiomegaly was present in 30 patients, and 16 patients had an ejection fraction of less than 30 p. 100. None of the patients were receiving digitalis or class I antiarrhythmic drugs when ablation was performed. A total of 235 shocks of 100 to 320 J (mean 221 +/- 42 J) were delivered. 115 shocks (49 p. 100) were complicated by dysrhythmia and/or disorders of conduction; 29 shocks (12 p. 100) induced 13 ventricular fibrillations and 16 ventricular tachycardias. No relation was found between energy delivered, shock synchronization, haemodynamic status, heart cavity treated, underlying heart disease, CK MB levels and these arrhythmias. On the other hand, ablations performed while the patients were experiencing VT increased the risk of arrhythmia (p less than 0.02). 36 AV blocks, 21 left bundle branch blocks, 12 right bundle branch blocks and 11 sinus bradycardia were observed. With the exception of one right bundle branch block and one left posterior hemi-block, all blocks were transient. IN PRACTICE: (1) electrode catheter ablation may be complicated by disorders of cardiac rhythm or conduction in 50 p. 100 of the cases; (2) these disorders can easily be corrected by stimulation or defibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Coping strategies in rheumatoid arthritis.

Our purpose was to investigate the importance of the coping process for patients with rheumatoid arthritis (RA). Eighty-four patients with classic or definite RA were examined. The relationship between coping strategies and psychological status, functional status, pain, and disease activity was analyzed. Coping was measured by an adapted version of the Ways of Coping Scale, and measures of psychological status, life stress, functional status, pain, and disease activity were also obtained. Canonical correlation revealed a significant relationship between the coping process and psychological status. Coping also was significantly related to functional status, but not to pain or disease activity. Patients who coped by restructuring life goals were found to have better psychological adjustment and functional status than patients who hoped for unrealistic solutions or engaged in self-blame.

Activities of Daily Living↗
PubMed1988

[Endocavitary fulguration in the treatment of cardiac arrhythmia].

Fulguration of the heart cavities seems currently to be a technique of increasing value in the treatment of untractable arrhythmias, of supraventricular junctional or ventricular origin. This study represents the evaluation of our experience with 64 patients, maximum follow-up is 54 months and the minimum follow-up is 7 months. Although the results are quite satisfactory in the fulguration of the bundle of his and in the fulguration of the arrhythmic site inducing ventricular tachycardia, these results are inferior in the Wolff-Parkinson-White syndrome in which fulguration of the coronary sinus seems contraindicated al filter (LEM type), resulting in the death of the patient. It is a true, early (1st week) migration after accurate positioning, opposite L4, and not an incident of insertion.

Adolescent↗
PubMed1988

[Surgical treatment of arrhythmia].

The surgical treatment of rhythm disorders began with interruption of the atrio-ventricular conduction by surgical section of the His bundle, then of the accessory path (Kent bundle) in the Wolff-Parkinson-White syndrome. Later on, surgery was extended to the treatment of chronic ventricular tachycardias. At a time when surgery seems to be progressively replaced by ablation methods using physical agents, electric shock or radio-frequency current, applied through endoluminal probes, it seemed justified to evaluate the established surgical procedures in the treatment of rhythm disorders. Therefore, this study proposes to review the current place of these methods which, in the last few years, have been modified in order to improve the quality of the results, decrease the mortality and specify their indications.

Arrhythmias, Cardiac↗
PubMed1988

[Sinocarotid hypersensitivity].

Hypersensitivity of the carotid sinus corresponds to a ventricular pause equal to or exceeding 3 seconds and/or a blood pressure drop equal to or exceeding 50 mmHg, induced by massage of the carotid sinus (MCS). MCS remains the diagnostic method of these two syndromes: cardio-inhibitor/vasodepressor. It must be performed systematically during the work-up of transient consciousness disorders since it is not unusual that hypersensitivity of the carotid sinus may cause cardiac syncopes. In addition, hypersensitivity of the carotid sinus is often associated with sinus dysfunction and atrioventricular conduction disorders. In the case of hypersensitivity of the carotid sinus with syncope secondary to a pure or dominant cardio-inhibiting response, heart stimulation with a dual-chamber pacemaker is probably the best treatment. In cases of hypersensitivity of the carotid sinus without syncope, therapeutic abstention is commonly accepted.

Arrhythmias, Cardiac↗
PubMed1988

Pain in rheumatoid arthritis: relationship to demographic, medical, and psychological factors.

Our purpose was to investigate the relationship among demographic, medical, and psychological factors and self-reported pain in 135 patients with classic or definite rheumatoid arthritis (RA). Patients were examined using the systemic index, articular index, McGill Pain Questionnaire, Symptom Checklist-90-R, and a pain visual analogue scale. Multiple regression analyses found no significant relationships between pain and the medical variables. However, age, income, and selected psychological variables were significantly correlated with pain reports. The greatest pain management challenge occurred in patients who were middle-aged, living on limited incomes, and experiencing major stresses in everyday life. These high risk pain patients were also worry-prone and felt isolated and lacking in social support. Attention to these related psychosocial problems is recommended as an important pain management strategy in RA.

Arthritis, Rheumatoid↗
PubMed1987

Crystal structure analysis of an A-DNA fragment at 1.8 A resolution: d(GCCCGGGC).

Single crystals of the self-complementary octadeoxyribonucleotide d(GCCCGGGC) have been analysed by X-ray diffraction methods at a resolution of 1.8 A. The tetragonal unit cell of space group P4(3)2(1)2 has dimensions of a = 43.25 A and c = 24.61 A and contains eight strands of the oligonucleotide. The structure was refined by standard crystallographic techniques to an R factor of 17.1% using 1359 3 sigma structure factor observations. Two strands of the oligonucleotide are related by the crystallographic dyad axis to form a DNA helix in the A conformation. The d(GCCCGGGC) helix is characterized by a wide open major groove, a near perpendicular orientation of base pairs to the helix axis and an unusually small average helix twist angle of 31.3 degrees indicating a slightly underwound helix with 11.5 base pairs per turn. Extensive cross-strand stacking between guanine bases at the central cytosine-guanine step is made possible by a number of local conformational adjustments including a fully extended sugar-phosphate backbone of the central guanosine nucleotide.

Crystallization↗
PubMed1987

Biochemical characterization of polypeptide components involved in neurite fasciculation and elongation.

Polypeptide components and carbohydrate linkage types of F11 antigen and G4 antigen, two chick cell-surface glycoproteins implicated in neurite fasciculation and elongation [Rathjen, F.G., Wolff, J.M., Bonhoeffer, F. and Rutishauser, U. (1987) J. Cell Biol. 104, 343-353], have been studied in comparison to mouse L1 antigen. Tryptic fingerprint analysis does not reveal any relation of the 130-kDa components of G4 or F11 antigens to each other or to neural cell-adhesion molecules. The 180/190-kDa component of G4 antigen comprises parts of the 130-kDa and 80/65-kDa components and shares a sequence corresponding to the amino terminus of the G4 130-kDa component as shown serologically with anti-peptide sera. This closely parallels the relationship found for mouse L1 antigen components. In contrast, the F11 170-kDa component is different from the F11 130-kDa component, as shown serologically and by fingerprint analysis. A combination of chemical and enzymatic deglycosylation methods reveals that while O-glycosylation cannot be detected F11 130-kDa, G4 130-kDa and L1 140-kDa components contain N-linked carbohydrates. Endoglycosidase H treatment shows that the oligosaccharides present in the G4 130-kDa component and mouse L1 are mostly of the complex type, while the F11 130-kDa component consists of two populations, one containing mainly complex-type carbohydrates and a second containing high-mannose/hybrid-type carbohydrates.

Amino Acid Sequence↗
PubMed1987

High-speed preparative reversed-phase high-performance liquid chromatography of synthetic oligonucleotides.

A rapid method is described for the purification and analysis of synthetic oligonucleotides, based on reversed-phase high-performance liquid chromatography. Volatile buffers and a short column (40 mm X 4.6 mm) packed with Nucleosil 300-5 C4 were employed. Monitoring the column effluent with an UV detector provides an excellent means of controlling product quality. The method is suitable for the purification of crude synthesis products, as well as for desalting and removing gel contaminants from oligonucleotides eluted from polyacrylamide gels. The total time required per sample is less than 25 min.

Chromatography, High Pressure Liquid↗
PubMed1987

The primary structure of human secretogranin I (chromogranin B): comparison with chromogranin A reveals homologous terminal domains and a large intervening variable region.

We have determined and analyzed the primary structure of human secretogranin I (chromogranin B), a tyrosine-sulfated secretory protein found in a wide variety of peptidergic endocrine cells. A 2.5-kb cDNA clone, hybridizing to an mRNA of similar length, was isolated from a cDNA library of human pheochromocytoma. The identity of the clone was established by comparison of its deduced amino acid sequence with N-terminal and several internal secretogranin I sequences as well as by immunoprecipitation of the protein produced by in vitro transcription-translation of the cloned cDNA. Secretogranin I is a 657 amino acid long polypeptide of 76 kd and is preceded by a cleaved N-terminal signal peptide of 20 residues. Comparison of the predicted amino acid sequence of human secretogranin I with that of bovine chromogranin A reveals significant homologies near the N termini and at the C termini. The N-terminal homologous domains contain the only two cysteine residues of both proteins and form disulfide-stabilized loop structures. The sequences between the homologous terminal domains in both proteins differ but are characterized by a remarkable hydrophilicity, an abundance of acidic amino acids and potential dibasic cleavage sites for the generation of smaller, perhaps hormone-like, peptides.

Adrenal Gland Neoplasms↗