Search PubMed⌕ Search

Biomedical subjects

R Frank

Publications and source records attributed to R Frank.

At least 433 records · Page 24Linked to original sources
PubMed1986

Treatment of resistant ventricular tachycardia with endocavitary fulguration and antiarrhythmic therapy, compared to antiarrhythmic therapy alone: experience in 111 consecutive cases with a mean follow-up of 18 months.

Endocavitary fulguration was performed in 31 cases of high-risk ventricular tachycardia (VT) for which antiarrhythmics, including Amiodarone and Class-I antiarrhythmic agents, given alone or in combination, proved ineffective. Permanent VT was incessant in nine patients at the time of fulguration: five of these were moribund, and two were unconscious. Included in the series were ten cases of arrhythmogenic right ventricular dysplasia, 13 cases of chronic VT after myocardial infarction, five cases of idiopathic dilated cardiomyopathy, two cases of idiopathic VT, and one case that involved a congenital anomaly. Combined fulguration and antiarrhythmic therapy succeeded in preventing VT in the 27 patients who survived the initial period of treatment. Thirteen patients needed two or more sessions, however, before their VT was brought under control. Three of the four early deaths were probably related to an imperfect technique. Four late deaths were due to spontaneous evolution of the disease. One patient without cardiac failure died suddenly. The follow-up period ranged from a minimum of 13 to a maximum of 34 months, with an average follow-up of nearly 2 years. The success rate for fulguration alone or for antiarrhythmic drugs is about 90%. This group of patients is compared with a group that involved 73 less severe cases treated with drugs. Fulguration appears to be the better form of treatment.

Journal Article↗
PubMed1986

[Treatment of resistant ventricular tachycardia with endocavitary ablation combined with anti-arrhythmia agents].

Catheter ablation was used in 26 consecutive cases of high risk ventricular tachycardia (VT) resistant to antiarrhythmic therapy. Seven patients were in permanent VT at the time of catheter ablation, three of them were moribund. There were 10 cases of arrhythmogenic right ventricular dysplasia, 9 cases of VT complicating chronic myocardial infarction, 4 cases of dilated cardiomyopathy, 2 cases of idiopathic VT and one congenital cardiac malformation. Ten patients required 2 or more sessions of catheter ablation to treat their arrhythmia. Three of the 4 early deaths (less than 1 month) were due to technical problems. Combined with antiarrhythmic drugs in 8 cases, catheter ablation brought the VT under control in the 22 remaining patients. The follow-up period ranges from 10 to 28 months (average follow-up longer than 17 months). Catheter ablation is a technique which is currently under evaluation. The very encouraging results obtained in this series suggest that it may replace surgery in the treatment of chronic refractory VT.

Adolescent↗
PubMed1986

[Anti-tachycardia radiofrequency pacemakers. Experience with 44 cases].

Programmed cardiac stimulation may be performed externally using implanted radiofrequency receiving capsules. Between 1979 and 1984, 44 patients underwent implantation of these devices, 12 with atrial leads for supraventricular tachycardias (8 orthodromic reciprocating tachycardias, 1 intranodal junctional tachycardia and 3 atrial tachycardias), and 32 with ventricular leads for ventricular tachycardias. In the first case the transmitter was given to the patients so that they could terminate the tachycardias themselves. In the second case, the transmitter was kept in the cardiology department. All patients were also prescribed prophylactic antiarrhythmic drugs. The radiofrequency method was effective in 11 out of 12 cases of supraventricular tachycardia with a follow-up period ranging from 24 to 65 months (average 45 +/- 11 months). In the ventricular tachycardia group, the device was used in 11 patients to terminate ventricular tachycardia and in all patients to evaluate the efficacy of the antiarrhythmic therapy by provocative programmed stimulation with a follow-up ranging from 2 to 81 month (average 24 +/- 20 months). This palliative therapeutic method has reduced the number of hospital admissions in these patients. The indications are relatively few because of the efficacy of currently available antiarrhythmic agents and the possibility of radical treatment of tachyarrhythmias by surgery or catheter ablation.

Adult↗
PubMed1986

Estimation of hexachlorobenzene pathways from the technosphere into the environment.

Since there are many different pathways from the technosphere to the environment, hexachlorobenzene (HCB) is widely distributed, supported by high mobility and high persistence. Several different assumptions were made about HCB inputs to air or water and, by simple calculations, potential HCB concentrations in water, air, sewage sludge and sediment were estimated. By comparing the results with measured environmental concentrations, maximum amounts of HCB released into the environment were estimated, and the relative importance of the water and air pathways appraised. Results showed that of the total HCB produced, the fraction that is released into the environment is substantially smaller than has been estimated. Despite the estimates of world-wide annual input of 10-100 t, it is well known that HCB is detected in relatively large amounts in most living tissues. This emphasizes the importance of the persistence of HCB, and of other environmental chemicals.

Air Pollutants↗
PubMed1986

[Anesthesia and surveillance in intracavitary fulguration for radical treatment of ventricular tachycardia].

Endocavitary fulguration, is a new technique to ablate the arrhythmogenic substrate of chronic ventricular tachycardias (VT). This method is used in patients with ventricular tachycardias of varied etiologies. 47 fulgurations in 36 patients with 40 hemodynamic and 12 myocardial metabolic studies are presented. In cardiopathies, the cardiac performance is altered with an ejection fraction of less than 50% and a ventricular function curve which is in Braunwald zone II. Ablation of the arrhythmia was obtained in 63% of cases. Severe complications were observed in 13% of cases, i.e.: low cardiac output, pulmonary oedema and myocardial ischemia. Three patients died from cardiac failure. Ventricular tachycardia was induced to localize the arrhythmogenic foci to be fulgurated. Ventricular tachycardia led to hemodynamic changes with a high pulmonary capillary wedge pressure and low cardiac output (-21%) which was further lowered under general anesthesia (-42%) due to poor response to tachycardia. Endocardial fulguration per se induced severe but transient (less than 5 minutes) hemodynamic changes and was sometimes complicated by myocardial ischemia and conduction disorders. General anesthesia is necessary to perform endocardial fulguration but cannot be induced with a poor hemodynamic state and with high rate ventricular tachy-arrhythmias. Three criteria are used concerning the anesthetic agents: 1) maintainance of cardiac contractility and baro-reflex efficiency; 2) respect of myocardial oxygen balance; 3) maintainance of excitability during mapping of arrhythmogenic foci. Hemodynamic monitoring is necessary to understand and manage complications due to this new type of therapy.

Adult↗
PubMed1985

Analysis of secondary structures in M13mp8 (+) single-stranded DNA by the pausing of DNA polymerase alpha.

The pausing of DNA replication has been used as a tool for analyzing secondary structures in a single-stranded DNA. M13mp8 (+) single-stranded DNA was replicated in vitro by the DNA polymerase alpha from calf thymus. The positions of pausing were determined from DNA sequencing gels. All experimentally observed pausing sites could be correlated with computer-predicted secondary structures of the M13 single-stranded DNA. In the computer calculations of the secondary structures, long-range base-pairing, G.T mispairs and loop-out of bases were allowed. By using six different primers, the pausing site pattern and the corresponding secondary structure map of a region comprising 1400 nucleotides of the M13 genome has been established. Our experiments indicate that the M13 DNA is highly structured. Most of the stable structures are clustered around the origin of replication. With fragments of the M13 DNA, we show that long-range base-pairing exists in the M13 single-stranded genome and we present evidence for tertiary structure interactions. Furthermore we observe structures that form newly during the course of replication. The Escherichia coli single-stranded DNA-binding protein facilitates replication through the barriers.

Animals↗
PubMed1985

Investigation of the tertiary folding of Escherichia coli 16S RNA by in situ intra-RNA cross-linking within 30S ribosomal subunits.

Intra-RNA cross-links were introduced into E. coli 30S ribosomal subunits by mild ultraviolet irradiation. The subunits were partially digested with cobra venom nuclease, followed in some cases by a second partial digestion with ribonuclease H in the presence of the hexanucleotide d-(CTTCCC). The cross-linked RNA complexes were separated by two-dimensional gel electrophoresis and the sites of cross-linking analysed by our published procedures. Tertiary structural cross-links in the 16S RNA were identified between positions 31 and 48, between oligonucleotides 1090-1094 and 1161-1164, and between oligonucleotides 1125-1127 and 1280-1281. The first of these imposes a rigid constraint on the relative orientations of helices 3 and 4 of the 16S secondary structure. A further tertiary cross-link (which could not be precisely localised) was found between regions 1-72 and 1020-1095, and secondary structural cross-links were identified between positions 497 and 545-548, and positions 1238-1240 and 1298.

Elapid Venoms↗
PubMed1985

On the fidelity of DNA polymerase alpha: the influence of alpha-thio dNTPs, Mn2+ and mismatch repair.

The phi X174am16 revertant system has been used to investigate the influence of alpha-thio-dNTPs and of Mn2+ on the fidelity of the 9S DNA polymerase alpha from calf thymus. Upon substituting dGTP by alpha-thio-dGTP during the in vitro replication, a nearly tenfold decrease in the frequency of G:G and G:T mispairs is observed. The formation of all other mispairs is not changed in the presence of the corresponding alpha-thio-dNTP. Mn2+ at concentrations of 0.5 mM does not influence the frequencies of the mispairs. The expression rate of errors formed during in vitro replication in the (-) strand has been determined for all mispairs detectable in the phi Xam16 system. The (-) strand expression of G:T, T:T and C:T mismatches is about 50%, whereas for A:G, G:G and C:A mismatches it is clearly below 50%. We conclude that the different base-base mismatches are repaired with different efficiencies.

Animals↗
PubMed1985

Stabilisation of human interferon beta synthesis in Escherichia coli by zinc ions.

Human interferon beta synthesized in Escherichia coli is unstable and toxic for the bacterial cell. Zinc ions are able to stabilise interferon beta in E. coli probably by inhibiting the action of cell internal proteinase(s) which affect the half-life of this foreign protein. As a result up to one order of magnitude more active IFN-beta can be detected in Zn2+-treated E. coli cells.

Cloning, Molecular↗
PubMed1985

The bacterial phosphoenolpyruvate-dependent phosphotransferase system. Isolation of active site peptides by reversed-phase high-performance liquid chromatography and determination of their primary structure.

Using reversed-phase high-performance liquid chromatography (HPLC) it was possible to isolate 32P-labelled active-site regions of various proteins from the bacterial phosphoenolpyruvate-dependent phosphotransferase system. The purified peptides obtained by proteolytic cleavage with Lys-C protease and trypsin were sequenced by the gas phase method. The fragments derived from enzyme I (MW 70 000) of two streptococcal species show 100% homology. The analogous peptide of Staphylococcus aureus Enzyme I differs in the N-terminal region. A labelled peptide from the glucose-specific enzyme III protein of Escherichia coli obtained by cleavage with alkaline protease was isolated and sequenced. It could be fitted into the primary structure of this protein, which was derived from DNA sequence data. The active-site histidine residue of this protein is therefore localized at position 91. The HPLC separation method described is suitable for the isolation of peptides derived from active sites containing labile amino acid derivatives such as phosphohistidines.

Amino Acid Sequence↗
PubMed1985

Properties of a mutant lactose carrier of Escherichia coli with a Cys148----Ser148 substitution.

The cysteine residue at position 148 in the lactose carrier protein of Escherichia coli has been replaced by serine using oligonucleotide-directed, site-specific mutagenesis of the lac Y gene. The mutant carrier is incorporated into the cytoplasmic membrane to the same extent as the wild-type carrier, confers a lactose-positive phenotype on cells, and actively transports lactose and other galactosides. However, the maximum rate of transport for several substrates is reduced by a factor of 6-10 while the apparent affinity is reduced by a factor of 2-4. Carrier activity in the mutant is much less sensitive to sulfhydryl reagents (HgCl2, p-(chloromercuri)benzenesulfonate and N-ethylmaleimide) than in the wild type, and beta-D-galactosyl 1-thio-beta-D-galactoside does not protect the mutant carrier against slow inactivation by N-ethylmaleimide. It is concluded that the Cys148 residue is not essential for carrier-catalyzed galactoside: proton symport and that its alkylation presumbly prohibits access of the substrate to the binding site by steric hindrance. A serine residue at position 148 in the amino acid sequence appears to alter the protein structure in such a way that one or more sulfhydryl groups elsewhere in the protein become accessible to alkylating agents thereby inhibiting transport. Recently, Trumble et al. [(1984) Biochem. Biophys. Res. Commun. 119, 860-867] arrived at similar conclusions by investigating a mutant carrier with a Cys148----Gly148 replacement.

Amino Acid Sequence↗
PubMed1985

[New cardiac pacemakers].

The new pacemakers are operated by lithium batteries, which gives them 5 to 10 years of life. They often contain a microcomputer controlling all their functions. The pacing rate, the energy of each impulse and the sensitivity to spontaneous cardiac potentials can be modified from outside by means of a programmer: the pacemaker can therefore be adapted to each patient, and some abnormalities in its functioning can be corrected without reoperating. It is often possible to interrogate these pacemakers on their setting and on the state of their battery, and they sometimes store in memory the patient's cardiac rhythm, thus acting as "implantable Holters". The so-called "physiological" pacemakers improve haemodynamics by increasing stimulation frequency during exercise, usually through detection of the atrial potential. Finally, the latest pacemakers are capable of controlling some atrial, junctional or ventricular tachycardias. It is for the latter that implantable defibrillators are intended.

Arrhythmias, Cardiac↗
PubMed1985

[Efficacy and side effects of long-term treatment with amiodarone. Retrospective study. Apropos of 460 cases].

A retrospective study was conducted in a group of 460 patients in order to evaluate the effectiveness and frequency of side effects of amiodarone over a mean observation period of 2 years. The effectiveness was considered to be excellent or good in 71.5 p. cent of cases of ischaemic heart disease, in 84.8 p. cent of cases of supraventricular arrhythmia and in 92.3 p. cent of cases of ventricular arrhythmia. Side effects were observed in 32.8 p. cent of patients and treatment had to be suspended in 19.8 p. cent of cases. The most frequent side effects were photosensitisation (11.9%), thyroid disorders (5.6%) and bradycardia or sinus dysfunction (11.9%). Some of these side effects appear to be related to the cumulative dose received.

Adolescent↗
PubMed1985

Phosphoenolpyruvate-dependent protein kinase enzyme I of Streptococcus faecalis: purification and properties of the enzyme and characterization of its active center.

Enzyme I, the phosphoenolpyruvate:protein phosphotransferase (EC 2.7.3.9), which is part of the bacterial phosphoenolpyruvate- (PEP) dependent phosphotransferase system, has been purified from Streptococcus faecalis by using a large-scale preparation. Size exclusion chromatography revealed a molecular weight of 140 000. On sodium dodecyl sulfate gels, enzyme I gave one band with a molecular weight of 70 000, indicating that enzyme I consists of two identical subunits. The first 59 amino acids of the amino-terminal part of the protein have been sequenced. It showed some similarities with enzyme I of Salmonella typhimurium. The active center of enzyme I has also been determined. After phosphorylation with [32P]PEP, the enzyme was cleaved by using different proteases. Labeled peptides were isolated by high-performance liquid chromatography on a reversed-phase column. The amino acid composition or amino acid sequence of the peptides has been determined. The largest labeled peptide was obtained with Lys-C protease and had the following sequence: -Ala-Phe-Val-Thr-Asp-Ile-Gly- Gly-Arg-Thr-Ser-His*-Ser-Ala-Ile-Met-Ala-Arg-Ser-Leu-Glu-Ile-Pro-Ala- Ile-Val-Gly-Thr-Lys-. It has previously been shown that the phosphoryl group is bound to the N-3 position of a histidyl residue in phosphorylated enzyme I. The single His in position 12 of the above peptide must therefore carry the phosphoryl group.

Amino Acid Sequence↗
PubMed1985

Assessing depression in primary medical and psychiatric practices.

A two-stage assessment of newly admitted outpatients at community mental health centers and primary medical care centers found the Center for Epidemiological Studies Depression Scale to be highly sensitive but relatively nonspecific when compared with assessments of depression by the Diagnostic Interview Schedule. Considerably higher than usual screening scores are recommended with both patient populations to improve the efficiency of the Center for Epidemiological Studies Depression Scale. The reasons for our finding that primary care clinicians underdiagnose depressive disorder while psychiatric clinicians overdiagnose it relative to the Diagnostic Interview Schedule include varied presentations by each sector's patients, differing clinical acumen, and factors affecting third-party reimbursement.

Adult↗