Inadequate Erythropoietin Response to Anaemia in HIV Patients: Relationship to Serum Levels of Tumour Necrosis Factor-Alpha, Interleukin-6 and Their Soluble receptors

Severe anaemia is a frequent complication in advanced HIV infection. In our study we investigated the interaction between cytokine network, HIV infection and erythropoietin (Epo) response with increasing anaemia levels. No correlations could be established between circulating tumour necrosis factor (TNF)-alpha and any of the examined parameters. However, a negative correlation was found between haemoglobin values and soluble TNF receptor levels (sTNF-R-I: r  = −0.54; P  < 0.001; sTNF-R II: r  = −0.47; P  < 0.001) as well as interleukin-6 levels ( r  = −0.29; P  < 0.001). In contrast, no significant increase in log[Epo], counterbalancing haemoglobin decline and paralleling the rise in sTNF receptors, was found. In patients classified as stage III, according to the Centers for Disease Control (CDC) classification, the erythropoietin response was significantly more impaired than in patients from CDC groups I and II ( P  < 0.001). The results of this study suggest that similar to its action in vitro , activation of the TNF/TNF-R system may impair erythropoietin production in HIV-associated anaemia. Due to the brief half-life of TNF-α, this activation is particularly reflected by elevations of soluble TNF receptor levels.     

Management of Patients After Catheter Ablation of Ventricular Tachycardia

The management of patients after catheter ablation of ventricular tachycardia is not well defined. In this article we summarize recently published results and report our own experience. Factors influencing the clinical outcome of these patients and methods to identify patients with an increased risk of recurrence of ventricular tachycardia are discussed. Furthermore, a review is given on current concomitant therapeutic tools including antiarrhythmic drugs and the implantation of an automatic cardioverter defibrillator.     

Embryotoxicity Study of Monomeric 4,4'-Methylenediphenyl Diisocyanate (MDI) Aerosol after Inhalation Exposure in Wistar Rats

One of the uses of MDI is as an alternative to formaldehydein the manufacture of furniture, its main route of exposureto humans being by inhalation. There have been no previous studieson the potential prenatal toxic effects of this compound. Toclose this gap in information, gravid Wistar rats, Crl:(WI)BR,were exposed by whole-body inhalation to clean air (control)and to 1, 3, and 9 mg/m3 MDI, respectively, for 6 hr per dayfrom Days 6 to 15 post conception (p.c). Rats were killed onDay 20 p.c. and the following results were obtained: Treatmentcaused a dose-dependent decrease in food consumption in allsubstance-treated groups during exposure, returning to normalvalues after cessation of treatment. The lung weights in thehigh-dose group were significantly increased compared to thesham-treated control animals. Treatment did not influence anyother maternal and/or fetal parameters investigated (maternalweight gain, number of corpora lutea, implantation sites, pre–and postimplantation loss, fetal and placental weights, grossand visceral anomalies, degree of ossification), although aslight but significant increase in litters with fetuses displayingasymmetric sternebra(e) was observed after treatment with thehighest dose of 9 mg/m³. Although the relevance of an increaseof this minor anomaly in doses which cause toxic effects indams (reduced food consumption, increased lung weights) is limitedand the number observed is within the limits of biological variability,a substance-induced effect in the high-dose group cannot beexcluded with certainty. Consequently, a no embryotoxic effectlevel of 3 mg/m³ was determined.     

Echocardiographic assessment of the haemodynamic effects of propofol: a comparison with etomidate and thiopentone

The haemodynamic effects of propofol (2 mg/kg), etomidate (0.2 mg/kg) and thiopentone (4 mg/kg) were studied in 30 ASA 1 and 2 patients in whom anaesthesia had been induced with midazolam 0.1 mg/kg, fentanyl 5 micrograms/kg, vecuronium 0.1 mg/kg and atropine 10 micrograms/kg, and maintained with nitrous oxide in oxygen. Arterial pressure was measured directly and left ventricular diameters were determined by transoesophageal echocardiography. Systolic blood pressure after propofol and thiopentone and the end-systolic quotient (systolic pressure/end-systolic diameter), a measure of inotropy, decreased. Fractional shortening (end-diastolic-end-systolic diameter/end-diastolic diameter) decreased only in the thiopentone group. Diastolic blood pressure and end-diastolic diameter (a measure of preload) did not change in any of the groups, and the etomidate group showed no changes in the haemodynamic variables measured. Propofol shows simultaneous negative inotropy and afterload reduction, while thiopentone is exclusively negatively inotropic.     

Influence of Different Conditioning Methods on Force and Fatigue Resistance in Chronically Stimulated Skeletal Muscles

A study was undertaken to compare different conditioning methods for the transformation of latissimus dorsi muscle into a fatigue resistant one for application in circulatory assist. In ten sheep four electrodes were sutured to the epineurium of the left thoracodorsal nerve for indirect electrical stimulation of the latissimus dorsi muscle. In six sheep a "carousel stimulation, " a special multichannel stimulation, in combination with a recently developed conditioning protocol was used for muscle conditioning ( multichannel method ). In four sheep, a conventional stimulation protocol using single channel stimulation was applied for transformation of the muscle (single channel method). The final experiments were carried out when fatigue resistance was obtained. The maximum tetanic forces at different preloads were determined and fatigue resistance was tested during 20 minutes of continuous stimulation. Both conditioning patterns led to fatigue-free chronic stimulation. Muscles conditioned by multichannel stimulation exhibited between 20% and 33% less force than the contralateral unconditioned muscles, whereas in the single channel group this loss was between 32% and 43%. Thus, the multichannel method revealed relatively superior in preserving muscle force for chronic stimulation.     

Doppler echocardiographic analysis of cardiac flow during the Mueller manoeuver

The inspiration against a closed airway, the Mueller manoeuver, leads to a negative intrathoracic pressure. It is controversially discussed whether this is causing an augmentation of right heart murmurs. There is only limited knowledge on the temporal relationship of the negative intrathoracic pressure with right and left ventricular filling and stroke volume. To investigate this relationship, the flow through the mitral, aortic, tricuspid and pulmonary valves was studied continuously by Doppler echocardiography during a standardized Mueller manoeuver in 15 healthy subjects (age 45 +/- 10 years). Five heart beats after the initiation of the manoeuver, flow through the mitral and aortic valve decreased 12.2 +/- 7.2% (P less than 0.001) and 10.1 +/- 6.6% (P less than 0.001), respectively. A transient increase of 15.1 +/- 9.2% (P less than 0.001) in tricuspid flow was followed by a 14.3 +/- 9.8% (P less than 0.005) increase of flow through the pulmonary artery. Ten heart beats after the initiation of the Mueller manoeuver, flow through the pulmonary artery again reached baseline, while tricuspid flow remained below baseline values. In contrast to previous studies, our results indicate that the Mueller manoeuver causes a small and transient increase in right ventricular stroke volume which is unlikely to cause a marked augmentation in right heart murmurs.     

EFFICIENCY OF THE LEFT VENTRICLE ASSIST DEVICE HEMOPUMP IN CARDIAC FIBRILLATION

We have examined in sheep the efficiency of the Hemopump duringventricular fibrillation. Circulatory arrest was induced byelectrical stimulation and maintained for 30 min. Haemodynamicmeasurements were recorded continuously and blood samples weretaken before, during and after fibrillation to determine totalbody and myocardial metabolic activity. All hearts were defibrillatedsuccessfully after 30 min of fibrillation. During fibrillation,the Hemopump sustained a mean arterial pressure of about 60mm Hg with a blood flow rate of about 2.3 litre min^–1.These perfusion conditions were sufficient for maintenance ofaerobic myocardial metabolism, but with a borderline circulatorysupply to the total organism.