PubMed Health⌕ Search

Biomedical subjects

H J Bretschneider

Publications and source records attributed to H J Bretschneider.

At least 37 records · Page 2Linked to original sources
PubMed1990

HTK-solution (Bretschneider) for human liver transplantation. First clinical experiences.

The cardioplegic HTK-solution (Bretschneider) has not been used in human liver transplantation as yet. Herein the first results obtained from 14 patients with HTK-preserved liver grafts are presented. The suitability of HTK-solution could be shown. All grafts functioned primarily except one, where initial non-function was obviously due to donor reasons. The early postoperative peak values of transaminases as a sign of ischemic damage were average and similar to the values of other flushout solutions. Using HTK primary function could be achieved even in livers prospectively assessed as only of fair quality, and livers with poor donor function tests (MegX) functioned from the beginning. HTK-solution therefore seems to allow widening of the acceptance criteria for donor livers. It was not the aim of this trial to extend cold ischemic time, but 3 livers with 11 h and 12 h 25 showed immediate function. How far cold ischemic time can be extended is a still open question. All livers were rapidly cooled and homogeneously flushed out due to the low viscosity of HTK-solution. All livers had a soft consistency after perfusion indicating a low degree of cell edema. HTK therefore is an effective solution for liver preservation.

Adenosine↗
PubMed1990

The surface to volume ratio of mitochondria, a suitable parameter for evaluating mitochondrial swelling. Correlations during the course of myocardial global ischaemia.

Cellular changes occurring in the left ventricular myocardium during ischaemia after different methods of cardiac arrest have been evaluated by morphological and morphometric parameters: volume densities of mitochondria (VVMi), sarcoplasm (VVSp), myofibrils (VVMf), surface densities of mitochondria (SVMi). The surface to volume ratio of mitochondria (SVratioMi) has been used as an independent parameter of mitochondrial swelling. Since ischaemic swelling of myocardial cells increases the volume of the reference space and ischaemic swelling of mitochondria decreases the free sarcoplasm, VVMi and VVSp cannot be considered as reliable indicators of the degree of oedema. SVMi/VVMf remains nearly constant after different forms of cardiac arrest, demonstrating the integrity of mitochondrial outer membranes. The inverse linear ratio between SVratioMi and the mean mitochondrial volume indicates that the increase in mitochondrial volume is achieved by surface smoothing. Loss of matrix structure and fragmentation of cristae occur at an SVratioMi of about 5.8, cristolysis at 5.5 to 5.6 and amorphous matrix densities at an SVratioMi of less than 5.5 micron2/micron3. The SVratioMi is a suitable parameter for evaluating mitochondrial swelling both at the onset and during global myocardial ischaemia, independent of the method of cardiac arrest used. It serves as an indicator of the state of structural preservation of mitochondria during ischaemia.

Animals↗
PubMed1990

Ultrastructural effects induced by global ischaemia on the AV node compared with the working myocardium. A qualitative and morphometric investigation on the canine heart.

The cardiac conduction system is considered to be particularly resistant to ischaemia. Nevertheless, following open heart surgery with short periods of ischaemia disturbances in AV conduction or ventricular arrhythmia have been reported. We compared the ultrastructure of AV node and working myocardium following 30 min global ischaemia at 25 degrees C, during pure ischaemia and with HTK cardioplegia qualitatively and morphometrically. After 30 min of pure ischaemia, interstitial and intracellular oedema together with considerable changes in organelles in AV nodes predominate over mainly cellular oedema in working myocardium. Sometimes irregular overcontractions of sarcomeres occur in the AV node, though very seldom in working myocardium. In pure ischaemia, mitochondrial swelling is comparable in both types of tissue. Following HTK cardioplegia and 30 min ischaemia, cellular oedema and mitochondrial swelling are significantly reduced in AV nodal cells and working myocardium, but remain more extensive in the AV nodes. Irregularities in the contractile state of sarcomeres are not observed. The extent of the ultrastructural alterations corresponds to the degree of metabolic change in the working myocardium. Thus, despite considerable differences during pure ischaemia and HTK cardioplegia, ultrastructurally the AV nodal cells do not display a greater resistance to ischaemia than working myocardium.

Animals↗
PubMed1990

Occurrence and prevention of contraction bands in Purkinje fibres, transitional cells and working myocardium during global ischaemia.

Contraction bands usually occur in the intramural working myocardium following post-ischaemic reperfusion. In the subendocardium, however, they are found during ischaemia. Thus, we ascertained the contraction states of Purkinje fibres, transitional cells, subendocardial and intramural parts of the working myocardium during 30 min global ischaemia at 25 degrees C. The effects with and without myocardial protection were compared. At the onset of pure ischaemia contraction bands are completely lacking in all cell types. During pure ischaemia contraction bands are found in all subendocardial cell types but not in the intramural working myocardium. A peak of pathological contraction states is found in the intramural working myocardium at the onset (0 min), in the subendocardial working myocardium at 10 min, in the transitional cells and Purkinje fibres at 30 min of pure ischaemia. Histidine-, tryptophan-, ketoglutarate-enriched (HTK) cardioplegia prevents contraction bands completely at the onset of ischaemia and prevents both contraction bands and pathological contraction states during ischaemia almost completely. Striking differences in the physiological contraction states are seen only in the working myocardium: HTK cardioplegia brings about dominance of relaxation during ischaemia. These findings may be due mainly to the effects of global ischaemia on the one hand and to catecholamines, calcium and oxygen on the other.

Animals↗
PubMed1990

Metabolic reduction in hypothermia: pathophysiological problems and natural examples--Part 1.

Following a description of the protective effects of hypothermia, the limitations resulting from "cold swelling" of the brain, caused by a progressive discrepancy between active and passive cellular transport processes, are discussed. The observation that the tolerable limits of metabolic reduction lie well below the normal turnover rates leads to a short survey of the evolution of energy metabolism. The gradual development of the latter from anaerobiosis to aerobiosis and from poikilothermy to homeothermy apparently provides the background for transient reductions to lower rates which spontaneously occur even in higher vertebrates. As an impressive example of such a natural strategy, the anaerobic survival of diving turtles is outlined which essentially depends on an efficient buffering. This dependence bears analogy to cardioplegia, where an increase in buffering capacity can greatly retard the fall of energy turnover, thus leading, as is shown by microcalorimetry, to an intermediate plateau of anaerobic metabolism.

Adaptation, Physiological↗
PubMed1990

Metabolic reduction in hypothermia: pathophysiological problems and natural examples--Part 2.

As an example of spontaneous cooling in homeothermic organisms, hibernation of mammals is described. Based on the fact that all hibernators, at their regulated minimal body temperature, display a uniform turnover rate, related to body weight, the hypothesis is developed that cold tolerance of mammals is generally limited by a common specific minimal metabolic rate, which larger organisms, because of their lower basal metabolism, already attain in less profound hypothermia. The observation that there is, in natural lethargic states, a certain independence between metabolic rate and body temperature, subsequently leads to considerations on the presumable modulating influence exerted by the acid-base balance. Finally, referring to the time limitations of such adaptation strategies, the cold-induced disintegration of metabolic processes with differing temperature dependence is illustrated which, however, will be more pronounced in the intermediate temperature range than in lower cooling. Thus, despite a limited cold tolerance, an extremely profound hypothermia of short duration seems not altogether impossible even for large homeotherms, provided some adequate conditions of rewarming are observed.

Acid-Base Equilibrium↗
PubMed1990

Influence of pretreatment on interstitial and intracellular space of canine left-ventricular myocardium.

In this study, the interstitial space and myocytes were investigated qualitatively and morphometrically in samples from beating, fibrillating as well as from cardioplegically HTK-arrested hearts fixed by immersion or perfusion. The size of tissue clefts separating bundles of myocytes and that of the interstitial space within bundles of myocytes depend on the functional state and on the kind of fixation. Cellular preservation is significantly better in HTK-arrested hearts compared to beating or fibrillating hearts. Thus, for the structural evaluation of myocytes and interstitium, the pretreatment constitutes a highly significant factor.

Animals↗
PubMed1990

Glucose content and efficiency of glycolysis in protected ischemic kidneys of different species.

In ischemic canine kidneys protected by Bretschneider's HTK solution the glycolytic lactate production is limited by a low renal substrate content. However, for anaerobic energy supply ischemic organs depend on glycolysis. To evaluate the role of glycolysis in renal protection, the relationship between lactate production and anaerobic energy supply was examined in protected kidneys of dogs, sheep, and swine. Additionally, in canine kidneys an attempt was made to improve anaerobic energy provision by adding glucose to the protective solution. The results were as follows: (1) According to increasing lactate production from swine to dog to sheep, intraischemic ATP decay was delayed least in swine and most in sheep. (2) Glucose addition (10 mM) to the HTK solution roughly doubled the time for ATP to fall to 1 mumol/g dry wt (tATP) in dogs. (3) The greater the lactate production in all three species, the lower the decrease in SAN (ATP + ADP + AMP) from 5 to 120 min of ischemia. (4) A glucose additive in the protective solution led to a significant (p less than .005) increase of SAN in dogs at 120 min of ischemia. A sufficient substrate supply seems to be an essential component of a reliable renal protection.

Adenine Nucleotides↗
PubMed1990

Heptanol effects on protected livers.

Heptanol, an agent known for inducing closure of gap junctions in a variety of organs, was used to evaluate the influence of uncoupling on the electrical impedance of livers during ischemia. Heptanol was added to a modified HTK solution or to Belzer's UW-CSS solution. Livers of swine were then perfused for 8 min with either one of the solutions containing heptanol or a solution devoid of this additive. During the following ischemia the phase angle of impedance at 5 kHz, pH and different biochemical parameters were determined. Heptanol fundamentally changed the time course of impedance and made the otherwise characteristic fast increase of the phase angle of impedance disappear. Already early during ischemia the phase angle was raised in a dose-dependent manner up to even highest values at the beginning of the whole observation period in case of a fully developed effect. Heptanol also stimulated anaerobic energy turnover. The results suggest that, besides unspecific effects, heptanol induces uncoupling which is detectable by electrical impedance measurement.

Alcohols↗
PubMed1990

Glycogen effects on energy state and passive electric properties of liver during protection.

In order to evaluate the importance of glycogen for the hepatic tolerance to ischemia, livers of swine fed a glucose-potassium solution for premedication were perfused with either Bretschneider's HTK-solution (histidine-tryptophan-ketoglutarate) or with Euro-Collins-solution (EC) prior to subsequent ischemia at 25 and 5 degrees C. During ischemia, in regular intervals or continuously, energy rich phosphates, lactate, intrahepatic pH and the electrical impedance of liver tissue were determined. The results were compared with corresponding data from swine which had starved for 48 h. Corresponding to the higher glycogen content, energy supply during ischemia was markedly improved by the premedication. Despite high amounts of glucose in the EC-solution, energy supply after glucose-potassium premedication was no better with EC-solution than with HTK-solution. Moreover, glucose uptake led to concomitant cellular water uptake. Electrical impedance measurements during ischemia mirrored improved energetical protection by the glucose-potassium premedication.

Acid-Base Equilibrium↗
PubMed1990

["Imperative indication" for organ-preserving kidney tumor surgery].

Imperative indications for organ-sparing surgery of renal tumors are given mainly in existing or imminent restriction of renal function. Organ-sparing excision of renal tumors under in-situ protection with HTK-solution compared with operations without protection have the following advantages: 1. reduced blood loss, 2. longer ischemia, 3. better tissue differentiation with benefit for radicality, 4. shorter hospital stay.

Cardioplegic Solutions↗
PubMed1989

Urinary LDH-release for evaluation of postischemic renal function.

Following renal ischemia under protection, the perfusion of the tubular system increases concomitant to the rise of GFR. The transport into urine of enzymes entering the tubular lumen due to ischemic injury is dependent on tubular flow. Thus, we examined if in the early postischemic phase urinary enzyme determinations can contribute to the evaluation of the ischemic injury despite the interference of a changing tubular washout. Canine kidneys were perfused with different protective solutions and subsequently rendered ischemic. From the beginning of reperfusion the endogenous creatinine clearance, the urine minute volume and the urinary LDH-concentration were determined. The urinary LDH-concentration allowed only a rough assessment of renal ischemic damage. The adjustment of the urinary LDH amounts to the GFR resulted in a better graduation according to the ischemic stress. With such a standardized LDH parameter the urinary LDH release was somewhat lower on the average when L-aspartate was added to the HTK solution in place of chloride. In conclusion, during the early postischemic recovery after renal protection the examination of the urinary enzyme release may be a useful diagnostic means for the assessment of the extent of the ischemic injury if an appropriate frame of reference is applied.

Animals↗
PubMed1989

The cardioplegic solution HTK: effects on membrane potential, intracellular K+ and Na+ activities in sheep cardiac Purkinje fibres.

The effects of the cardioplegic solution HTK on membrane potential (EM) and intracellular K and Na activities (aiK, aiNa) were studied in sheep cardiac Purkinje fibres by means of conventional and ion-selective microelectrodes. HTK contains (mM): Na 15, K 10, Ca 0, Mg 4, histidine 180. (1) In control conditions EM was -74.3 +/- 3.3 mV (n = 25), aiK was 116.4 +/- 4.1 mM (n = 7) and aiNa was 8.2 +/- 1.4 mM (n = 15). (2) Exposure to HTK led to a depolarization to -59.7 +/- 3.6 mV (n = 25) which exceeded by about 5-7 mV that induced in a Tyrode solution of 10 mM K and in a modified HTK solution supplemented by 2 mM Ca (n = 6). (3) Addition of 0.5 mM barium eliminated the difference in the steady-state depolarization. (4) HTK superfusion increased aiK to 120.1 +/- 4.4 mM (n = 7) and decreased aiNa to 3.9 +/- 0.9 mM (n = 15). (5) The decrease in aiNa was insensitive to amiloride (1 mM) and to external alkalization but was slightly increased by addition of 2 mM calcium. (6) When the calcium in Tyrode solution was lowered from 2.0 mM to 0.05 mM, aiNa hardly decreased during subsequent exposure to unmodified HTK and it increased in the presence of 0.1 mM dihydroouabain. We propose the hypothesis (1) that the difference in membrane depolarization between HTK and a 10 mM K-Tyrode is caused by a decrease in K conductance by the HTK solution and (2) that the aiNa decline mainly results from a coupled Ca influx via Na-Ca exchange due to a delayed washout of external calcium.

Animals↗
PubMed1989

Intraischemic metabolic effects of different disaccharides on protected canine kidneys.

The addition of the disaccharides maltose (10, 20, 30 mM) and sucrose (30, 60 mM) to Bretschneider's organ protective HTK solution was evaluated to improve renal protection by an enhanced glycolytic energy supply. Canine kidneys were perfused for 8 min with either HTK solution or HTK solution containing additional disaccharides. After nephrectomy the kidneys were incubated at 25 degrees C and metabolic parameters were determined at regular intervals. Maltose and sucrose are slowly cleaved during renal ischemia but maltose distinctly faster than sucrose. Maltose increases intraischemic ATP supply. However, 30 mM maltose was no better than 10 mM. 60 mM sucrose was about as effective for glycolysis as 10 mM maltose. However, possibly due to fructose release there was an accelerated decrease of adenine nucleotides with sucrose. Although fructose enters glycolysis it seems to have negative side-effects. Hence, probably neither sucrose nor fructose are appropriate for renal substrate supply during ischemia.

Adenosine Triphosphate↗
PubMed1989

Contribution of amino acids in protective solutions to postischemic functional recovery of canine kidneys.

Amino acids are known to increase glomerular filtration rate (GFR). There is also an early resumption of filtration following 2-h renal ischemic stress under protection by histidine-buffered histidine-tryptophan-ketoglutarate solution (HTK), possibly due in part to an amino acid effect. Hence, we have examined the possibility of further enhancing the postischemic GFR by adding 32 (ASP I; 4 mM Mg2+) or 36 (ASP II; 6 mM Mg2+) mM L-aspartate (asp) or 32 mM DL-aspartate (ASP III) to the HTK solution in place of chloride. After infusion of 500 ml 5% glucose, canine kidneys were protected by an 8-min perfusion with HTK (n = 5), ASP I (n = 4), ASP II (n = 5) or ASP III-solution (n = 3). The subsequent ischemia lasted for 2 h at 27-31 degrees C. During reperfusion, both GFR and filtration fraction (FF) were higher in kidneys protected by L-aspartate-containing solutions. ASP III showed no improvement against HTK. An additional preischemic intra-aortal application of HTK or ASP I solution just above the exit of the renal arteries prior to the intrinsic protective perfusion further raised the postischemic GFR. The present results suggest that L-aspartate but also histidine may have favorable amino acid effects in renal protective solutions in addition to known positive effects of histidine.

Animals↗
PubMed1989

Postischaemic interrelations between energy metabolism and functional recovery of protected canine kidneys.

Following renal ischaemia under effective protection glomerular filtration starts at a time when renal high-energy phosphates are resynthesized. The present investigation was carried out to examine the interdependence of the two processes. Therefore, canine kidneys were protected with sodium poor and nominally Ca2+ free buffered solutions. After different times of ischaemia and reperfusion the glomerular filtration rates (GFR) were determined and afterwards tissue specimens were excised for the determination of high-energy phosphates. Both the GFR and the renal energy content were higher with shorter ischaemia periods or longer reperfusion. As a rule there was a correlation between GFR and ATP, both probably mainly signifying the degree of preservation of proximal nephron sites, as the interrelation between the GFR and the renal SAN (ATP + ADP + AMP) content also signifies. However, with the addition of aspartate to the protective solution it could be demonstrated that the GFR also can rise without a concomitant increase of ATP. Under certain conditions an increase of GFR can even be associated with a lowering of the renal ATP content.

Adenosine Monophosphate↗