Myocardial beta-adrenoceptor changes in heart failure: concomitant reduction in beta 1- and beta 2-adrenoceptor function related to the degree of heart failure in patients with mitral valve disease.

In patients suffering from end-stage congestive cardiomyopathy, cardiac beta 1-adrenoceptor function is markedly reduced, whereas cardiac beta 2-adrenoceptor function is nearly normal. To determine whether beta 1-adrenoceptor function is impaired in heart failure selectively, beta 1- and beta 2-adrenoceptor density and functional responsiveness in the right and left atria and the left papillary muscles from patients with mitral valve disease (functional class III to IV) were studied. In all three tissues concomitantly beta 1- and beta 2-adrenoceptor density gradually declined when the degree of heart failure increased from functional class III to IV. This decrease in beta 1- and beta 2-adrenoceptor density was accompanied by similar decreases in the contractile response of isolated electrically driven right atrial and left ventricular papillary muscles to beta-adrenergic agonists. It is concluded that a decrease in cardiac beta-adrenoceptor function is a general phenomenon in heart failure, and its extent is related to the degree of heart failure. However, in contrast to congestive cardiomyopathy, in mitral valve disease the decrease in cardiac beta-adrenoceptor function is due to a concomitant decrease in beta 1- and beta 2-adrenoceptors.

Selective regulation of beta 1- and beta 2-adrenoceptors in the human heart by chronic beta-adrenoceptor antagonist treatment.

1. In 44 patients undergoing coronary artery bypass grafting, the effect of chronic administration of the beta-adrenoceptor antagonists sotalol, propranolol, pindolol, metoprolol and atenolol on beta-adrenoceptor density in right atria (containing 70% beta 1- and 30% beta 2-adrenoceptors) and in lymphocytes (having only beta 2-adrenoceptors) was studied. 2. beta-Adrenoceptor density in right atrial membranes and in intact lymphocytes was assessed by (-)-[125I]-iodocyanopindolol (ICYP) binding; the relative amount of right atrial beta 1- and beta 2-adrenoceptors was determined by inhibition of ICYP binding by the selective beta 2-adrenoceptor antagonist ICI 118,551 and analysis of the resulting competition curves by the iterative curve fitting programme LIGAND. 3. With the exception of pindolol, all beta-adrenoceptor antagonists increased right atrial beta-adrenoceptor density compared to that observed in atria from patients not treated with beta-adrenoceptor antagonists. 4. All beta-adrenoceptor antagonists increased right atrial beta 1-adrenoceptor density; on the other hand, only sotalol and propranolol also increased right atrial beta 2-adrenoceptor density, whereas metoprolol and atenolol did not affect it and pindolol decreased it. 5. Similarly, in corresponding lymphocytes, only sotalol or propranolol increased beta 2-adrenoceptor density, while metoprolol and atenolol did not affect it and pindolol decreased it. 6. It is concluded that beta-adrenoceptor antagonists subtype-selectively regulate cardiac and lymphocyte beta-adrenoceptor subtypes. The selective increase in cardiac beta 1-adrenoceptor density evoked by metoprolol and atenolol may be one of the reasons for the beneficial effects observed in patients with end-stage congestive cardiomyopathy following intermittent treatment with low doses of selective beta 1-adrenoceptor antagonists.

Chronic beta 1-adrenoceptor antagonist treatment sensitizes beta 2-adrenoceptors, but desensitizes M2-muscarinic receptors in the human right atrium.

1. In 64 patients undergoing coronary artery bypass grafting the effects of chronic beta 1-adrenoceptor antagonist (metoprolol, atenolol, bisoprolol) treatment on right atrial beta-adrenoceptor and muscarinic M2-receptor number and functional responsiveness were investigated. 2. The beta 1-adrenoceptor antagonists increased right atrial beta 1-adrenoceptor number, did not affect beta 2-adrenoceptor number, and decreased muscarinic M2-receptor number. 3. Concomitantly, activation of right atrial adenylate cyclase by 10 microM GTP, 10 microM isoprenaline and 1 microM forskolin was enhanced and inhibition by 100 microM carbachol was diminished. 4. On isolated, electrically driven right atria the beta 1-adrenoceptor-mediated positive inotropic effect of noradrenaline was - even with beta 1-adrenoceptor number increased - not altered, while the beta 2-adrenoceptor-mediated effect of procaterol was markedly enhanced. However, the carbachol-induced negative inotropic effect was decreased. 5. It is concluded that chronic beta 1-adrenoceptor antagonist treatment increases beta 1-adrenoceptor number and concomitantly sensitizes beta 2-adrenoceptor function, but desensitizes muscarinic M2-receptor function in the human heart.

Sequential bilateral lung transplantation for pulmonary alveolar microlithiasis.

Lung transplantation has been successfully used in the treatment of patients with end-stage pulmonary disease and adequate cardiac function. We report about a 32-year-old man with pulmonary alveolar microlithiasis who underwent sequential bilateral lung transplantation. Preoperative hemodynamic studies revealed severe pulmonary hypertension; the right ventricular ejection fraction was 0.27. Eighteen months postoperatively, he continues to do well with normalized pulmonary and cardiac function and without clinical or histopathologic signs of graft rejection.

Subtype-selective up-regulation of human saphenous vein beta 2-adrenoceptors by chronic beta-adrenoceptor antagonist treatment.

To study beta-adrenoceptor antagonist-induced changes in human vascular beta-adrenoceptors, we determined the effects of chronic treatment with different beta-adrenoceptor antagonists without intrinsic sympathomimetic activity (ISA) on beta 2-adrenoceptor density (assessed by (-)-[125I]-iodopindolol binding) in human saphenous vein membranes obtained from patients undergoing coronary artery bypass grafting. In patients chronically treated with the non-selective beta-adrenoceptor antagonists propranolol or sotalol, the density of saphenous vein beta 2-adrenoceptors was significantly higher than in control (i.e. patients not treated with beta-adrenoceptor antagonists), whereas in patients chronically treated with the selective beta 1-adrenoceptor antagonists metoprolol or bisoprolol it was not different from control. It is concluded that beta-adrenoceptor antagonists without ISA increase human saphenous vein beta 2-adrenoceptors in a subtype-selective fashion.

Muscarinic cholinoceptors in the human heart: demonstration, subclassification, and distribution.

In human atrial and ventricular myocardium, the muscarinic cholinoceptor (M-cholinoceptor) populations were characterized by means of radioligand binding (with [N-methyl-3H]-scopolamine ([3H]-NMS) as the ligand) and functional experiments (negative inotropic effect of carbachol on isolated electrically driven right atrial and left papillary muscle preparations). (1) Binding of [3H]-NMS to human atrial and ventricular membranes was rapid, reversible and saturable (KD-values: 0.5-1.0 nmol/l). The maximal number of [3H]-NMS binding sites, however, was approximately 2.5-fold higher in right and left atrial membranes (200-250 fmol [3H]-NMS specifically bound/mg protein) than in right and left ventricular membranes (80-100 fmol/mg protein). (2) M-cholinoceptor antagonists inhibited [3H]-NMS binding to right atrial and left ventricular membranes with steep, monophasic competition curves indicating interaction with a single class of binding sites. In both tissues the order of potency was: atropine greater than AF-DX 116 greater than hexahydrosiladifenidol (HHSiD) greater than pirenzepine. (3) On isolated electrically driven right atrial and left papillary muscle preparations (with force of contraction enhanced by 10(-5) mol/l isoprenaline), carbachol (10(-8)-10(-4) mol/l) caused concentration-dependent decreases in force of contraction; the pD2-value for carbachol was 6.65 +/- 0.09 (n = 8, atria) and 6.62 +/- 0.08 (n = 10, papillary muscles). In both tissues M-cholinoceptor antagonists antagonized the negative inotropic effect of carbachol with an order of potency: atropine greater than AF-DX 116 greater than HHSiD greater than pirenzepine, identical to that obtained in radioligand binding experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Endothelial damage of the venous graft in CABG. Influence of solutions used for storage and rinsing on endothelial function.

A significant proportion of early graft occlusions after aortocoronary revascularization using autologous saphenous vein grafts (SVG) are due to mechanical and/or metabolic or biochemical endothelial lesions. The morphological examination of the endothelium, usually carried out using light microscopy or by various types of scanning electron microscopy (SEM), does not give any indication of the functioning of the endothelium (E). Functionally intact E is capable of producing endothelium-derived relaxing factor (EDRF); a practicable in vitro test is the relaxation of pre-contracted vein segments (VS) in response to acetylcholine (ACh) application. To study the effect of the solution used to rinse and store the SVG between removal and implantation on the functional characteristics of the E, we performed in vitro tests on macroscopically intact VS removed from the saphenous vein of 30 male patients who underwent elective CABG surgery. Isolated VS rings were incubated for 60 min in heparinized whole blood (HWB), Bretschneider's cardioplegic solution (HTK), human albumin solution (HAS), or Ringer's solution (RS) and compared with the results obtained immediately after the removal of untreated control samples (C) taken from the same patients. After equilibration in carbogen aerated Krebs-Henseleit solution and precontraction by 3 x 10(-7) M noradrenaline (NE), relaxation induced by 10(-6) M ACh was measured. Only the samples stored in HWB (13.4 +/- 0.4 mN) showed similar maximal contractions with NE to those in the control group (14.4 +/- 0.5 mN), i.e. all those segments which showed both contractions with NE and relaxation with ACh.(ABSTRACT TRUNCATED AT 250 WORDS)

A paragenetic perspective on integration of RNA silencing into the epigenome and its role in the biology of higher plants.

We describe features of RNA silencing and associated epigenetic imprints that illustrate potential roles for RNA interference (RNAi) in maintenance and transmission of epigenetic states between cells, throughout a plant, and perhaps even across sexual generations. Three types of transgenes can trigger RNAi of homologous endogenous plant genes: (1) "sense" transgenes that overexpress translatable transcripts, (2) inverted repeat (IR) transgenes that produce double-stranded RNA (dsRNA), and (3) antisense transgenes. Each mode of RNAi produces a different characteristic developmental silencing pattern. Single-copy transgenes are sufficient for sense-RNAi and antisense-RNAi, but not inverted repeat-RNAi. A single premature termination codon dramatically attenuates sense-RNAi, but it has no effect on antisense or inverted repeat-RNAi. We report here that antisense transgenes altered by removal of nonsense codons generate silencing patterns characteristic of sense-RNAi. Duplication of a sense overexpression transgene results in two types of epigenetic events: (1) complete loss of silencing and (2) altered developmental pattern of silencing. We also report that duplicating only the transgene promoter results in complete loss of silencing, whereas duplicating only transcribed sequences produces the second class, which are vein-based patterns. We infer that the latter class is due to systemic RNA silencing signals that interact with certain epigenetic states of the transgene to imprint it with information generated at a distance elsewhere in the plant.

Management of extensive lesions of the lower trachea using emergency cardiopulmonary bypass.

Rapid cardiopulmonary deterioration in patients with extensive lesions of the lower trachea presents a serious challenge in the emergency care. Conventional methods may prove inadequate to achieve airway control and to stablilize the critical condition. Severe airway obstruction and/or massive air leakage are the main causes of failure. An aggressive operative approach is mandatory. Institution of emergency cardiopulmonary bypass for resuscitative purposes and definitive surgical repair of those life-threatening uncommon tracheal lesions seems essential to us. Two cases, managed according to this concept, are presented.

[Femoro-axillary bypass--a rarely used form of revascularization in occlusions of the supra-aortic vessels]. / Der femoro-axillare Bypass--eine selten genutzte Revaskularisationsform bei Verschlüssen supraaortaler Gefässe.

Revascularization of central occluded supraaortic vascular branches is more and more successfully done by extra-anatomic junction to the nearest other supraaortic vessel. In case of extreme stenosis of all supraaortic donor vessels intrathoracic surgery may be excluded in poor risk patients. The only possibility of extra-anatomic junction remains connection to iliaco-femoral vessels according to the well known femoro-axillary bypass. Showing two typical cases, this method is demonstrated proving its importance in elective and emergency surgery. The first patient (67 yrs. of age) showed an acute complete ischemia of the right arm due to obstruction of the subclavian artery distal of the origin of the truncus brachiocephalicus. Emergency operation was performed, and revascularization was achieved by femoro-axillary bypass because of biological inoperability to all other orthopic procedures. The second case is of a 66 yrs. old patient with abdominal aortic aneurysm and multiple stenoses of the supraaortic vessels. The abdominal aortic aneurysm was electively operated upon, and during the same operation the cerebral circulation was hemodynamically improved by performing a femoro-subclavian bypass. In considering these two cases, indications, risks and benefits of extra-anatomic revascularization procedures are discussed.

[Catheter break in an implantable central venous infusion system with embolization in the pulmonary artery]. / Katheterbruch eines implantierbaren zentralvenösen Infusionssystems mit Embolisation in die Arteria pulmonalis.

A central venous catheter with a subcutaneous infusion port was implanted for chemotherapy into a 64-year-old woman with gastric lymphoma. Six weeks later, two weeks after a trivial trauma with hyperextension of the shoulder joint, it was found that the catheter had broken and its tip portion had embolized into the pulmonary artery: it was retrieved without difficulty via the femoral vein. This event suggests that pressure between clavicle and first rib can cause material fatigue in a silicon catheter. Such catheters should therefore not be implanted via the subclavian vein.

Conduit-integration in correction of right ventricular outflow obstruction.

A new method for correction of right ventricular flow tract obstruction is described. The method combines the advantages of patch-plasty-procedure and external valved conduit by conduit integration into the right ventricular and pulmonary arterial wall. Good results had been achieved in 3 cases (2 cases of Fallot's tetralogy and one case of double outlet right ventricle).

A maturase-encoding group III twintron is conserved in deeply rooted euglenoid species: are group III introns the chicken or the egg?

The fourth intron of the Euglena gracilis chloroplast photosystem II gene, psbCi4, is a 1,605-bp twintron composed of two group III introns and a coding locus for a 458-aa polypeptide, mat1, located in the internal intron. psbCi4 homologs have been identified in seven euglenoids, including E. myxocylindracea, E. viridis, E. deses, E. pisciformis, Cryptoglena pigra, Eutreptia sp., and Lepocinclis beutschlii. All of the species examined contain both the group III twintron and the mat1 locus, revealing a more widespread occurrence of group III introns than previously known. The L. beutschlii mat1 locus is interrupted by two novel mini-group II introns of 224 and 258 nt, the smallest group II introns yet identified. Reverse transcriptase polymerase chain reaction analysis confirmed the splicing boundaries of the external and internal E. myxocylindracea, E. viridis, and E. deses introns as well as the novel L. beutschlii mat1 introns. As determined by comparative phylogenetic analysis, group III introns contain a structural homolog of group II intron domain VI. The mat1 loci encode peptide motifs characteristic of group II intron maturases. A group III intron-encoded protein whose predicted sequence is similar to group II intron-encoded maturases and a bona fide domain VI within group III introns are compelling evidence for a common ancestor of group II and group III introns.

[Vena cava superior thrombosis following placement of internal jugular vein catheter (author's transl)]. / Vena cava superior Thrombose nach Anlegen eines Jugularis interna Katheters.

Internal jugular vein puncture is suggested to be the safest route for placement of central venous catheter. One advantage is the lack of ensuing thrombosis. However, the case described demonstrates the occurrence of this complication. A 72-year old female developed severe thrombosis of the vena cava superior 5 days after placement of an internal jugular vein catheter. Thrombectomy was successfully performed during extracorporal circulation.

[The concept of lung and heart-lung preservation within the scope of multiple organ procurement]. / Konzept zur Lungen- und Herz-Lungen-Präservation im Rahmen der Multiorganentnahme.

Preservation of the lung is still one of the most challenging problems, because due to limited procurement time not all organs available can be used. The most common procurement technique is flush perfusion of the pulmonary artery system. Alternative methods in clinical use are either the autologous working heart-lung preparation or donor core-cooling (DCC). The own concept presented here, modified to the special demands of multi-organ-procurement, combines DCC and interstitial equilibration adapted to intracellular ion concentration. DCC is induced by extracorporeal circulation (ECC) using a transportable heart lung machine including a highly effective cooling system: cooling circuit based on two parallel heat exchangers with ice-water cooling produced by a high-pressure overflow of a low-temperature ice block (-40 degrees C). While cooling by ECC stepwise hemodilution is achieved by priming volume and incorporation of the cardioplegic solution (Bretschneider-HTK). The aim of equilibration is to lower the extracellular levels of sodium and calcium, and to increase the level of potassium. Additionally, the buffer capacity of donor blood is increased by the incorporated histidine-buffer system (alpha-stat). To avoid donor organ edema the time of ECC should be as short as possible. Using our system donor organ temperatures below 10 degrees C are reached within less than 30 min. In addition to ECC, lung surface cooling is achieved by external overflow with cold arterial blood (internal mammary artery). Besides lung preservation the main advantage of this concept is the profound precooling of all visceral organs before their individual flush perfusion.

Long-term results following surgical removal of pulmonary metastases in children with malignomas.

Between 1972 and June 1983, 21 children (mean age 9 years, range 20 months to 16.5 years) were operated on for pulmonary metastatic disease. Primary malignant tumors were Wilms-tumor (7 patients), osteogenic sarcoma (7 patients), Ewing's sarcoma (4 patients), hepatoblastoma (2 patients), and rhabdomyosarcoma (1 patient). The surgical intervention was part of a therapeutic pediatric oncological concept with curative purpose including chemotherapy and/or radiation in different combinations. Ten out of these 21 children survived disease-free 3 years and more after pulmonary metastasectomy. An aggressive surgical approach towards pulmonary metastatic disease in children thus appears to be justified.

Survival after heart and coronary-artery penetration by an air-rifle projectile.

Gunshot injuries of the heart are extremely rare thoracic traumas in Europe during peacetime. Concomitant lesions of the coronary arteries occur in less than 5%. This case reports on a 26-year-old man who was shot with an air rifle at short range. On admission the patient showed signs of pericardial tamponade. Emergency thoracotomy was performed and a frontal cardiac lesion was found in the distal third of the anterior descending branch of the left coronary artery. The bullet crossed the cavum of the left ventricle and remained in the posterior wall in the subepicardial layer adjacent to the posterior descending coronary branch. Under the conditions of extracorporeal circulation we removed the bullet, repaired both ventricle walls using patches in sandwich technique, and bypassed the coronary lesion by single aortocoronary venous graft. No signs of myocardial infarction could be detected by ECG. The follow-up after 3 years shows no cardiac problems and normal stress tolerance. This case report proves that even air rifle shots, which in general are considered to be harmless, may result in life-threatening injuries. For the severity of the injury are decisive the kinetic energy at the muzzle as well as configuration and type of the bullet.

Alternative lead positioning in the right ventricular outflow tract in transvenous implantation of ICDs.

Pacing and sensing failure in apical right ventricular coil electrode PCD implantation due to ventricular scars or aneurysma may force the implanting surgeon to switch to more invasive procedures such as subxyphoidal pericardiotomy or thoracotomy for epimyocardial corkscrew electrode and for epicardial patch application. In order to avoid this more invasive operation in the most severely impaired patients, right ventricular outflow tract positioning of the RV electrode is suggested as an alternative RV electrode site for implantation. A study of four cases shows that this occasional procedure is a practicable method to avoid more invasive techniques. Excellent pacing, sensing, and defibrillation characteristics were obtained and application is relatively simple.

[Primary cardiac tumours: diagnosis and surgical treatment (author's transl)]. / Primäre Herztumoren. Diagnostische Klärung und chirurgische Therapie.

A teratoma of the cardiac skeleton, a rhabdomyoma of the right ventricle and an intramural fibroma in the left ventricle were observed in three children, aged eight weeks, eight months and eight years, respectively. Atrial myxoma was found in a 42-year-old and a 49-year-old patient. History and symptoms showed no particular common features in the various patients, merely signs of flow obstruction in four of the five patients. Amongst specific cardiological diagnostic methods only angiocardiography was reliable in the demonstration of intra- or paracardiac space-occupying lesions. All five patients were successfully operated on under cardiopulmonary bypass. The surgical technique varied according to localisation, extent of the tumour and its site in relation to essential cardiac structures. Follow-up examination indicated that the patients were free of symptoms and recurrence.

Characterization of the glnK-amtB operon of Azotobacter vinelandii.

To determine whether in Azotobacter vinelandii the PII protein influences the regulation of nif gene expression in response to fluxes in the ammonium supply, the gene encoding PII was isolated and characterized. Its deduced translation product was highly similar to PII proteins from other organisms, with the greatest degree of relatedness being exhibited to the Escherichia coli glnK gene product. A gene designated amtB was found downstream of and was contranscribed with glnK as in E. coli. The AmtB protein is similar to functionally characterized ammonium transport proteins from a few other eukaryotes and one other prokaryote. glnK and amtB comprise an operon. Attempts to isolate a stable glnK mutant strain were unsuccessful, suggesting that glnK, like glnA, is an essential gene in A. vinelandii. amtB mutants were isolated, and although growth on limiting amounts of ammonium was similar in the mutant and wild-type strains, the mutants were unable to transport [14C]methylammonium.