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Biomedical subjects

E Hoffmann

Publications and source records attributed to E Hoffmann.

At least 37 records · Page 2Linked to original sources
PubMed2003

[15-year-old patient with decompensated heart failure and tachycardia with negative P-waves in inferior ECG recordings. An indication for heart transplantation?].

A 15-year-old girl was admitted with signs of severe cardiac failure. There were no symptoms of cardiac insufficiency 4 weeks before hospital admission. She presented with permanent supraventricular tachycardia with negative P-waves in leads II, III and aVF, the heart rate was 150 beats per minute. The electrophysiological examination showed a permanent junctional reentry tachycardia. A postero-septal accessory pathway could be eliminated successfully by radiofrequency catheter ablation. Immediately after the procedure cardiac function deteriorated with slight decrease of the strongly reduced cardiac output. Intensive care and application of dobutamine led to clinical stability. During a follow-up of two years the young patient showed permanent sinus rhythm and an age related physical strain. This case report documents the rapid and severe manifestation of cardiac failure owing to permanent junctional reentry tachycardia in a 15-year-old girl. She was referred for consideration of heart transplantation. Invasive electrophysiological treatment led to permanent sinus rhythm with improvement of left ventricular function.

Adolescent↗
PubMed2003

Risk factors for recurrence of atrial fibrillation in patients undergoing hybrid therapy for antiarrhythmic drug-induced atrial flutter.

AIMS: Catheter ablation of the inferior vena cava-tricuspid annulus isthmus and continuation of antiarrhythmic drug therapy have been shown to be an effective hybrid therapy for atrial flutter which results from antiarrhythmic drug treatment of atrial fibrillation. The aim of this study was to determine the risk factors for recurrence of atrial fibrillation in patients undergoing hybrid therapy for antiarrhythmic drug-induced atrial flutter. METHODS AND RESULTS: 90 patients with paroxysmal (n=46) or persistent atrial fibrillation (n=44) developed atrial flutter due to the administration of amiodarone (n=48), flecainide (n=22), propafenone (n=14) or sotalol (n=6). Recurrence of atrial fibrillation after ablation was assessed during follow-up on continued antiarrhythmic drug therapy and during long-term follow-up, irrespective of the initial antiarrhythmic medication. During the follow-up on continued antiarrhythmic drug therapy (16+/-13 months), recurrence of atrial fibrillation was documented in 24 of 90 patients (27%). The presence of accompanying pre-ablation episodes of atrial fibrillation on antiarrhythmic treatment (Odds ratio 7.1, 95% confidence interval 2.3 to 25, p=0.001) and decreased left ventricular ejection fraction (Odds ratio 3.7, 95% confidence interval 1.01 to 12.5, p=0.048) were significant and independent predictors of post-ablation atrial fibrillation. Antiarrhythmic medication was discontinued during long-term follow-up due to adverse drug effects (amiodarone, n=12; flecainide, n=1) in 13 patients (14%). During the long-term follow-up, irrespective of the initial antiarrhythmic medication (21+/-15 months), stable sinus rhythm was maintained in 60 of 90 patients (67%). CONCLUSION Hybrid therapy can be considered as the first line therapy for patients with antiarrhythmic drug-induced atrial flutter but patients should be carefully evaluated for accompanying pre-ablation episodes of atrial fibrillation and possible adverse drug effects before initiation of hybrid therapy.

Analysis of Variance↗
PubMed2003

Effects of two Gbetagamma-binding proteins--N-terminally truncated phosducin and beta-adrenergic receptor kinase C terminus (betaARKct)--in heart failure.

Myocardial overexpression of the C-terminus of beta-adrenergic receptor kinase (betaARKct) has been shown to result in a positive inotropic effect or an improvement of survival in heart failure. However, it is not clear whether this beneficial effect is mainly because of dominant-negative inhibition of betaARK1, and a consecutive resensitization of beta-adrenergic receptors (betaAR), or rather due to inhibition of other Gbetagamma-mediated effects. In this study, we tested whether overexpression of N-terminally truncated phosducin (nt-del-phosducin), another Gbetagamma-binding protein that does not resensitize betaARs owing to simultaneous inhibition of GDP release from Galpha subunits, shows the same effects as betaARKct. Adenoviral gene transfer was used to express nt-del-phosducin and betaARKct in isolated ventricular cardiomyocytes and in myocardium of rabbits, which suffered from heart failure because of rapid ventricular pacing. BetaAR-stimulated cAMP formation was increased by betaARKct, but not by nt-del-phosducin, whereas both proteins inhibited Gbetagamma-mediated effects. Both transgenes also increased contractility of normal and failing isolated cardiomyocytes and improved contractility in rabbits with heart failure after gene transfer in vivo. In conclusion, overexpression of nt-del-phosducin enhances the contractility of cardiomyocytes to the same extent as betaARKct, suggesting that the effects of betaARKct might be owing to inhibition of Gbetagamma rather than to betaAR resensitization.

Adenoviridae↗
PubMed2003

Land-based birds as potential disseminators of avian mammalian reassortant influenza A viruses.

Chickens, quail, and other land-based birds are extensively farmed around the world. They have been recently implicated in zoonotic outbreaks of avian influenza in Hong Kong. The possibility that land-based birds could act as mixing vessels or disseminators of avian/mammalian reassortant influenza A viruses with pandemic potential has not been evaluated. In this report, we investigated whether chickens and Japanese quail are susceptible to a mammalian influenza virus (A/swine/Texas/4199-2/98 [H3N2]). This virus did not grow in chickens and replicated to low levels in Japanese quail but did not transmit. Replacing the H3 gene of this virus for one of the avian H9 viruses resulted in transmission of the avian/swine reassortant virus among quail but not among chickens. Our findings demonstrated that Japanese quail could provide an environment in which viruses like the A/swine/Texas/4199-2/98 [H3N2] virus could further reassort and generate influenza viruses with pandemic potential.

Animals↗
PubMed2003

Haemorheological pattern in young adults with acute myocardial infarction.

Acute myocardial infarction (AMI) in young people has recently received great attention. Its main characteristics include a typical risk factor profile and a good prognosis. We studied the haemorheological pattern (whole blood viscosity at high and low shear rates, plasma and serum viscosity, whole-blood filtration and erythrocyte aggregation) in 64 subjects, aged <46 years, with recent AMI. We observed marked alterations in blood, plasma and serum viscosity and whole-blood filtration. Subdividing the AMI subjects in accordance with the number of cardiovascular risk factors or the extent of coronary lesions, we did not observe any significative influence of these aspects on the haemorheological determinants, with the exception of low shear rate blood viscosity. The latter was in fact higher than in control subjects only in AMI subgroups with respectively more risk factors and more stenosed coronary vessels. Thirty-three AMI subjects were re-examined after three months and showed, on this occasion, a haemorheological pattern not significantly different from that of the first evaluation. These results demonstrate that in young subjects with AMI there is a hyperviscosity syndrome that persists during subsequent months, despite a good clinical course. Haemorheological impairment may unfavourably influence the long-term prognosis of AMI in young subjects and therefore, in our opinion, management should take into account the monitoring of the haemorheological pattern.

Adult↗
PubMed2003

[Sacroiliac fixation: a new technique after pelvic trauma].

We propose a new technique for sacroiliac fixation for the treatment of pelvic fracture with vertical and horizontal instability (Tile class C). This fixation technique allows control of vertical displacement while allowing, if needed, a certain degree of movement in the horizontal plane to facilitate reduction of anterior lesions. The technique involves insertion of two sacral screws, one in S1 and one in S2, and two iliac screws. The iliac screws are inserted in the posterior iliac crest through two sacroiliac connectors placed on a rod linking the two sacral screws. Vertical displacement is controlled by blocking the screw heads on the connecting rod. If needed, a certain degree of horizontal mobility of the half pelvis can be allowed by loosening the connectors on the rods. This technique was used for 4 patients. Anatomic reduction was achieved and no secondary movement of the osteosynthesis material nor secondary displacement were observed. The quality of the fixation allowed rapid weight bearing in the standing position and early walking without crutches. This type of fixation can only be used for type C12 fractures in the Tile classification.

Adult↗
PubMed2002

Control of Cl- transport in the operculum epithelium of Fundulus heteroclitus: long- and short-term salinity adaptation.

The eurohaline fish, Fundulus heteroclitus, adapts rapidly to enhanced salinity by increasing the ion secretion by gill chloride cells. An increase of approximately 70 mOsm in plasma osmolarity was previously found during the transition. To mimic this in vitro, isolated opercular epithelia of seawater-adapted Fundulus mounted in a modified Ussing chamber were exposed to an increase in NaCl and/or osmolarity on the basolateral side, which immediately increased I(SC). Various Cl(-) channel blockers as well as the K(+) channel blocker Ba(2+) added to the basolateral side all inhibited the steady-state as well as the hypertonic stimulation of I(SC). The exists -agonist isoproterenol stimulates I(SC) in standard Ringer solutions. In contrast, when cell volume was kept at the larger value by simultaneous addition of water, the stimulation with isoproterenol was abolished, suggesting that the key process for activation of the Na(+), K(+), 2Cl(-) cotransporter is cell shrinkage. The protein kinase C (PKC) inhibitor chelerythrine and the myosin light chain kinase (MLCK) inhibitor ML-7 had strong inhibitory effects on the mannitol activation of I(SC), thus both MLCK and PKC are involved. The two specific protein kinase A (PKA) inhibitors H-89 and KT 5720 had no effect after mannitol addition whereas isoproterenol stimulation was completely blocked by H-89. This indicates that PKA is involved in the activation of the apical Cl(-) channel via c-AMP whereas the shrinkage activation of the Na(+), K(+), 2Cl(-) cotransporter is independent of PKA activation. The steady-state Cl(-) secretion was stimulated by an inhibitor of serine/threonine phosphatases of the PP-1 and PP-2A type and inhibited by a PKC inhibitor but not by a PKA inhibitor. Thus, it seems to be determined by continuous phosphorylation and dephosphorylation involving PKC but not PKA. The steady-state Cl(-) secretion and the maximal obtainable Cl(-) secretion were measured in freshwater-adapted fish and in fish retransferred to saltwater. No I(SC) could be measured in freshwater-adapted fish or in the fish within the first 18 h after transfer to saltwater. As evidenced from Western blot analysis using antiserine-antibodies, a heavily serine phosphorylated protein of about 190 kDa was consistently observed in the saltwater-acclimated fish, but was only weakly present in freshwater-acclimated fish. This observation indicates that acclimatization to saltwater stimulates the expression of this 190-kDa protein and/or a serine/threonine kinase, which subsequently phosphorylates the protein.

Acclimatization↗
PubMed2002

An in vivo pilot study characterizing the new CYP2A6*7, *8, and *10 alleles.

We developed genotyping assays for CYP2A6*7 (Ile471Thr) and CYP2A6*8 (Arg485Leu). We found higher allelic frequencies in Japanese and Chinese versus Caucasians and identified an allele in which both substitutions occur together (CYP2A6*10). We created a homology model for predicting the impact of allelic variants on enzymatic activity and subsequently tested this in vivo in a pilot kinetic study. Consistent with our homology model predictions, we found (i) that CYP2A6*7 produces an enzyme that has decreased (not inactive) activity for metabolizing nicotine and coumarin; (ii) that CYP2A6*8 is unlikely to affect catalytic activity in vivo; and (iii) that having both substitutions together on an allele (CYP2A6*10) dramatically reduces function and may be fully inactive for some substrates. In conclusion, this study identifies, at relatively high frequency in Asians, an allele with decreased activity (may be substrate selective), a fully functional allele, and an allele containing both substitutions in which function is dramatically reduced.

Alleles↗
PubMed2002

[Surgical and interventional use of radiofrequency current: is there interference with implantable cardioverter/defibrillators?].

BACKGROUND: During surgical and interventional procedures, interactions between implantable cardioverter defibrillators (ICD) and electrical cautery, respectively, application of radiofrequency (RF) energy may occur. Induction of inadequate shock therapies or device malfunction may result and represent a potential perioperative hazard for the patient. METHODS: Hence, we analyzed the intraoperative interactions in 23 consecutive ICD patients with regard to different surgical and interventional procedures. Sixteen surgical operations (general surgery n = 7, urologic n = 5, abdominal n = 2, gynecological n = 1, thoracic n = 1) and 7 interventional therapies (RF catheter ablation n = 5, endoscopic papillotomy n = 2) were performed. The ICD devices were all located in the left pectoral position and consisted of 15 single and 8 dual chamber defibrillators. During the procedure tachyarrhythmia detection (VF 295 +/- 21 ms, VT 370 +/- 55 ms) of the devices was maintained active (monitoring mode); only ICD therapies were inactivated. The indifferent electrode of the electrical cauter/RF generator was placed in standard positions (right mid femoral position n = 18, thoracic spine area n = 5). After the procedure, the ICD memory was checked for detections, respectively, for changes of the programming. RESULT: There was no misdetection or reprogramming of the ICD caused by electrical cautery or RF energy. CONCLUSIONS: Despite the lack of undesired interactions ICDs should be inactivated preoperatively to assure maximum patient safety. However, should inactivation be ineffective or not manageable, electromagnetic interference is highly unlikely.

Adult↗
PubMed2002

[Mechanisms of initiation in atrial fibrillation].

Atrial fibrillation is the most relevant arrhythmia in daily clinical practice. The pathophysiology is determined by multiple independent reentrant wavelets in both atria. Repetitive triggers and an underlying substrate may favor the initiation and maintenance of atrial fibrillation. Mapping studies in patients with drug-refractory paroxysmal atrial fibrillation identified potentials from the ostia of pulmonary veins as a main source of triggers that initiate atrial fibrillation. In ongoing clinical trials, catheter ablation of pulmonary vein foci is used to eliminate atrial premature beats and thereby prevent the initiation of atrial fibrillation. The autonomic modulation of the heart rate and the occurrence of other supraventricular tachycardias that degenerate into atrial fibrillation are also considered as triggering mechanisms of atrial fibrillation. Since symptomatic bradycardia is associated with an increased incidence of atrial fibrillation, atrial pacing therapies for prevention of atrial fibrillation are another concept. Ongoing clinical trials evaluating the efficacy of pacing in patients with and without a primary pacemaker indication are currently under investigation. To date, data to which extent anatomical and electrophysiological characteristics of the atria influence the initiation and maintenance of atrial fibrillation are still missing. The myocardial adaptation to atrial fibrillation, the so-called "atrial remodeling", includes shortening of the atrial refractory period, slowing of atrial conduction, shortening of the atrial action potential, a progressive reduction of L-type calcium channel expression and microfibrosis of the myocardial tissue. New drug developments target atrial remodeling by modulating ion channel function and receptors of the angiotensin metabolism.

Action Potentials↗
PubMed2002

Evaluation of aluminum-silicate polymer composite as a coagulant for water treatment.

Aluminum-silicate polymer composite (PASiC), a new kind of inorganic coagulant, was produced by two approaches: (1) hydroxylation of the mixture of AlCl3 and fresh polysilicate (PASiCc); (2) hydroxylated polyaluminum-chloride (PAC) combined with fresh polysilicate (PASiCm). The PASiC products had the following properties: Al2O3 content = 6.40-7.30%, SiO2 content = 0.40-0.82%, Al/Si ratios = 10-20, basicity (OH/Al molar ratio, denoted B) = 1.2-2.0. The coagulation behaviour of PASiC and PAC under conditions typical for coagulation and flocculation in water treatment were investigated by studying the rate of floc size development, the variety of streaming current value, the efficiency of turbidity removal and the effect of pH on the turbidity removal efficiency, and the stability of PASiC. The results detailed in this study suggest that, compared with PAC, PASiC may enhance aggregating efficiency and give better coagulating effects, but weaken charge effectiveness in coagulation process or become unstable when stored for longer time, especially at higher B value and lower Al/Si ratio. The coagulating effect of PASiC is closely linked to the preparation procedure. With the increase of B value and the decrease of Al/Si ratio, the coagulation efficiency of PASiC increases, and at the same B value and Al/Si ratio, PASiCc seems to give a little better coagulation effect than PASiCm but less stability. The Al/Si ratio should not be too low or the B value should not be too high, otherwise, the PASiC products tend to become cloudy or partly gelatinous, which will make them loss some coagulation efficiency.

Aluminum Silicates↗
PubMed2002

Complexity of biomedical data models in cardiology: the Intranet-based AF registry.

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with major complications. Ongoing research is focused on new pacing devices for alternative treatment of this disease. The objective of an AF registry is to store prospectively all relevant data covering clinical information, quality of life and device parameters and by this means provide a platform for long-term follow-up. For statistical analysis, categorical and numerical items are required, thus a high-granular data structure must be defined and implemented in the clinical setting. Facing the limits of formalization, we developed an XML-based documentation scheme consisting of 619 items in eight tables and implemented it with state-of-the-art Intranet technology. At present detailed information on 88 patients is recorded. The pacing device generates per patient and follow-up visit a file consisting of approximately 400-500 parameters provided on a floppy disk, which are transferred by means of a specific interface into the database. Success factors for integration of a complex research database into the routine workflow of a busy university hospital are interfaces between data sources to enable non-redundant data entry, intensive fine tuning by iterative software engineering and benefit for the clinical users in form of clinical reports and patient-specific summaries. Data quality must be assured by plausibility checks. To get an overview of this complex dataset we developed a dedicated visualization tool. Due to the high number of items a large patient collective must be recruited for statistical evaluation. Interinstitutional cooperation is required for a consensus on common minimal documentation schemes to enable pooling of data.

Atrial Fibrillation↗
PubMed2002

The effect of carbonate on the precipitation of calcium phosphate.

In order to facilitate the recovery of phosphorus from wastewater, the effect of carbonate on the precipitation of calcium phosphate has been studied. The effect of carbonate concentrations up to 5.00 millimoles per liter on the precipitation of 20 milligrammes phosphorus per liter phosphate was studied. At pH 8.00 the precipitation rate of phosphate was greatly retarded by carbonate and the corresponding precipitation efficiency also decreased, but at pH values > or = 9.00 the effect of carbonate on the precipitation of phosphate was very small. This indicates that carbonate may decrease the precipitation rate and efficiency of calcium phosphate, but the solution pH value is still a key factor influencing the precipitation process. The effect of carbonate on the precipitation of phosphate was attributed to the formation of ion pairs between carbonate and calcium and the decrease of free calcium ions. This resulted in the decrease of the thermodynamic driving force for the precipitation of calcium phosphate, so the effect of carbonate on the precipitation of phosphate was in fact a competing one, although this competing effect was not so obvious at pH > or = 9.00. Carbonate may be coprecipitated with phosphate from solution, especially at pH 9.00-11.00, and this will decrease the relative phosphorus content of the precipitate. The increases in solution pH value and initial Ca/P ratio are two approaches to overcome the influence of carbonate on the precipitation of phosphate, but the solution pH values should be lower than 10.00 and the initial Ca/P ratios should not exceed 5.00.

Calcium Phosphates↗
PubMed2002

Molecular evolution of H6 influenza viruses from poultry in Southeastern China: prevalence of H6N1 influenza viruses possessing seven A/Hong Kong/156/97 (H5N1)-like genes in poultry.

The A/teal/Hong Kong/W312/97 (H6N1) influenza virus and the human H5N1 and H9N2 influenza viruses possess similar genes encoding internal proteins, suggesting that H6N1 viruses could become novel human pathogens. The molecular epidemiology and evolution of H6 influenza viruses were characterized by antigenic and genetic analyses of 29 H6 influenza viruses isolated from 1975 to 1981 and 1997 to 2000. Two distinct groups were identified on the basis of their antigenic characteristics. Phylogenetic analysis revealed that all H6N1 viruses isolated from terrestrial poultry in 1999 and 2000 are closely related to A/teal/Hong Kong/W312/97 (H6N1), and the nucleotide sequences of these viruses and of A/Hong Kong/156/97 (H5N1) were more than 96% homologous. The hemagglutinin (HA) of the 1999 and 2000 terrestrial viruses does not have multiple basic amino acids at the site of cleavage of HA1 to HA2; however, a unique insertion of aspartic acid in HA1 between positions 144 and 145 (H3 numbering) was found. The neuraminidase of these terrestrial H6N1 viruses has a deletion of 19 amino acids characteristic of A/Hong Kong/156/97 (H5N1). Evolutionary analysis suggested that these H6N1 viruses coevolved with A/quail/Hong Kong/G1/97-like H9N2 viruses and became more adapted to terrestrial poultry. These terrestrial 1999 and 2000 A/teal/Hong Kong/W312/97 (H6N1)-like viruses, along with the H9N2 viruses, could have been involved in the genesis of the pathogenic H5N1 influenza viruses of 1997. The presence of H6N1 viruses in poultry markets in Hong Kong that possess seven of the eight genes of the A/Hong Kong/156/97 (H5N1) virus raises the following fundamental questions relevant to influenza pandemic preparedness: could the pathogenic H5N1 virus reemerge and could the H6N1 viruses directly cross the species barrier to mammals?

Animals↗
PubMed2001

Persistent hypercapnia in children after treatment of obstructive sleep apnea syndrome by adenotonsillectomy.

Obstructive sleep apnea syndrome (OSAS) in childhood is frequently in part a consequence of enlarged adenoids and/or tonsils and may lead to hypoxemia and hypercapnia during sleep. Whereas long-term blood gas alterations are well documented in adults, only few polygraphic data are available for children. It was the aim of this study to document blood gas alterations before and after treatment in this population. 9 children with OSAS (6 male, 3 female, median age 5.9 years, range 1.1-13.5 years) were investigated by polysomnography before and after adenotonsillectomy. Prior to intervention most children presented with moderate hypercapnia (ETCO2 mean 44.3 +/- 3.8 mm Hg, ETCO2 maximum 53.2 +/- 5.2) and hypoxemic episodes (oxygen saturation mean 93.2 +/- 3.2%, minimum 74.4 +/- 16.5%). Following adenotonsillectomy subsequent polygraphic investigations displayed normalisation of oxygen saturation (saturation mean 96.1 +/- 0.8%, minimum 90.1 +/- 3.1%). In contrast, moderate hypercapnia in several patients persisted up to five months after treatment (ETCO2 mean 44.9 +/- 2.8 mm Hg, ETCO2 maximum 51.2 +/- 3.6). Persistent hypercapnia most likely reflects an adaptation process of chemosensitivity and respiratory control due to preceding long-term hypercapnia.

Adaptation, Physiological↗
PubMed2001

Gene transfer of heterologous G protein-coupled receptors to cardiomyocytes: differential effects on contractility.

In heart failure, reduced cardiac contractility is accompanied by blunted cAMP responses to beta-adrenergic stimulation. Parathyroid hormone (PTH)-related peptide and arginine vasopressin are released from the myocardium in response to increased wall stress but do not stimulate contractility or adenylyl cyclase at physiological concentrations. To bypass the defective beta-adrenergic signaling cascade, recombinant P1 PTH/PTH-related peptide receptors (rPTH1-Rs) and V(2) vasopressin receptors (rV(2)-Rs), which are normally not expressed in the myocardium and which are both strongly coupled to adenylyl cyclase, and recombinant beta(2)-adrenergic receptors (rbeta(2)-ARs) were overexpressed in cardiomyocytes by viral gene transfer. The capacity of endogenous hormones to increase contractility via the heterologous, recombinant receptors was compared. Whereas V(2)-Rs are uniquely coupled to Gs, PTH1-Rs and beta(2)-ARs are also coupled to other G proteins. Gene transfer of rPTH1-Rs or rbeta(2)-ARs to adult cardiomyocytes resulted in maximally increased basal contractility, which could not be further stimulated by adding receptor agonists. Agonists at rPTH1-Rs induced increased cAMP formation and phospholipase C activity. In contrast, healthy or failing rV(2)-R-expressing cardiomyocytes showed unaltered basal contractility. Their contractility and cAMP formation increased only at agonist exposure, which did not activate phospholipase C. In summary, we found that gene transfer of PTH1-Rs to cardiomyocytes results in constitutive activity of the transgene, as does that of beta(2)-ARS: In the absence of receptor agonists, rPTH1-Rs and rbeta(2)-ARs increase basal contractility, coupling to 2 G proteins simultaneously. In contrast, rV(2)-Rs are uniquely coupled to Gs and are not constitutively active, retaining their property to be activated exclusively on agonist stimulation. Therefore, gene transfer of V(2)-Rs might be more suited to test the effects of cAMP-stimulating receptors in heart failure than that of PTH1-Rs or beta(2)-ARS:

Adenoviridae↗