Biomedical subjects

M Kallerhoff

Publications and source records attributed to M Kallerhoff.

47 records · Page 3Linked to original sources

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↗

PubMed1988

Metabolic, energetic and structural changes in protected and unprotected kidneys at temperatures of 1 degree C and 25 degrees C.

In 110 canine kidneys, we examined the time course of energy rich phosphates, lactate, intrarenal ph and renal morphology with Euro-Collins- or with HTK-protection of Bretschneider and compared these findings with unprotected kidneys during complete ischemia at 1 degree C and at 25 degrees C. Both kidney protective solutions prolonged energy-rich phosphate-decline by a factor of 3-4 compared with that of unprotected kidneys. The lactate increase was greater in Euro-Collins-protected kidneys than in HTK-protected and in unprotected kidneys, leading to pH values of 6.5 in Euro-Collins and to 6.4 in unprotected kidneys after 24 hours, in contrast to a pH-value of 7.3 with HTK-protection. This may be the reason for structural deterioration seen in unprotected and in Euro-Collins-protected kidneys after 12, and 48 h of ischemia at 1 degree C, whereas in HTK-protected kidneys a sufficient preservation of structure can be seen. In one human kidney, protected with Euro-Collins-solution, we were able to show that at 1 degree C intrarenal pH and lactate accumulation is similar to the levels in canine kidneys. In Euro-Collins preserved kidneys lactate accumulation at 25 degrees C is even greater than at 1 degree C, leading to inhibition of energy metabolism and to structural deterioration, whereas HTK-solution, because of its high buffer concentration, is able to maintain ischemic metabolism leading to sufficient protection of intrarenal pH and of adenine nucleotides as well as structural protection at 1 degree C and at 25 degrees C.

Animals↗

PubMed1988

[Clinical use of the Bretschneider HTK cardioplegic solution for in situ protection of the kidney].

The first clinical use of Bretschneider's HTK-solution for in-situ-protection of the kidney in mild hypothermia is reported. By means of this protective method renal surgery can be performed in a bloodless field without permanent loss of renal function. After initial protective perfusion of the kidney no repeated perfusions or additional surface cooling must be done. There are no systemic side effects when the HTK-solution is applied appropriately.

Cardioplegic Solutions↗

PubMed1987

Short-term perfusion and "equilibration" of canine kidneys with protective solutions.

Kidneys were perfused either with Euro-Collins-solution or with HTK-solution of Bretschneider. The perfusion pressure as well as the perfusion flow were measured during a six-minute perfusion. The perfusion resistance was higher in Euro-Collins-kidneys than during HTK-perfusion. The venous outflow of the kidney as well as the ureteral outflow was measured during each minute of the perfusion and has analysed for osmolality, and for sodium and potassium concentrations. In Euro-Collins-kidneys a complete "equilibration" of the extracellular space was not achieved, while during HTK-perfusion concentrations in the venous as in the tubular outflow, similar to those in the HTK-solution itself, could be reached. At the end of the different perfusions, tissue was analysed for biochemical parameters such as ATP, ADP, AMP and lactate as well as for morphological features. Lactate had increased and ATP had decreased during perfusion with Euro-Collins-solution, while ATP had not changed and lactate had decreased during perfusion with HTK-solution. Normal glomerular, tubular and dilated vascular structures can be seen after HTK-perfusion, while a glomerular and vascular contraction takes place during Euro-Collins-perfusion.

Adenine Nucleotides↗

PubMed1987

Effects of glucose in protected ischemic kidneys.

Energy reserves (TAN) and anaerobic substrates (glucose, glycogen) are lower in renal than in myocardial tissue. Euro-Collins-solution contains nearly 200 mmol/l glucose, while the HTK-solution of Bretschneider contains none. Therefore the influence of glucose on kidney lactate production, on energy reserves (TAN), intrarenal pH and on morphology during the protection of ischemic kidneys was analysed using either Euro-Collins-solution, or modified "Euro-Collins-solution", containing mannitol instead of glucose, or HTK-solution with and without the addition of 5, 10 and 20 mmol/l glucose. Glucose content changed during kidney perfusion with Euro-Collins-solution from about 60 to 800 mumol/gdw. While intrarenal pH decreased from 7.1 to 5.1 in Euro-Collins-kidneys during 420 min of ischemia at 25 degrees C, pH decreased to 6.7 with the modified, mannitol containing "Euro-Collins-solution". In HTK-protected kidneys intrarenal pH decreased with increasing glucose addition to the solution. Although Total Adenine Nucleotides are highest at the end of ischemia with Euro-Collins-solution, structural protection after the same ischemic stress was best in HTK-protected kidneys without glucose addition. We conclude that glucose stimulated lactate production, reduced interstitial pH in the kidney even in combination with a highly buffered solution and that it might cause greater membrane permeability leading to a structural deterioration. Mannitol seemed more appropriate than glucose in this respect, although other substances, which provide energy substrate and prevent structural damage, may exist.

Acidosis↗

PubMed1987

[Kidney function parameters following ischemia stress using the Euro-Collins solution or the Bretschneider cardioplegic HTK solution].

Protection-methods, for an improvement of ischemic tolerance of the kidney, can be investigated by intraischemic analysis of metabolism and structure. A definite proof for the effectiveness of a protection method is only postischemic function in combination with postischemic structure-regeneration. For this reason postischemic function was chosen for examination of the protective ability of the Euro-Collins-solution and the HTK-solution during a two-hour reperfusion period. We perfused 57 dog kidneys either with the Euro-Collins- or with the HTK-solution prior to ischemia. Ischemia was 7, 60, 90 and 120 min after Euro-Collins-perfusion and 7, 120, 150 and 180 min after HTK-protection. The protected and ischemic kidneys were left in-situ; the mean ischemic temperature was therefore 20-25 degrees C for the shorter ischemic times and 30-34 degrees C for the longer ischemic times. We compared the protected and ischemic kidneys with 14 untreated kidneys (control). Postischemic renal blood flow (RBF) was measured by an electromagnetic flow probe; renal oxygen consumption (V02/min) was calculated by arterio-venous oxygen content difference and the renal blood flow. If urine could be collected, the glomerular filtration rate (GFR) was measured by an endogenous creatinine clearance. In Euro-Collins-protected kidneys after 60-120 min ischemia the RBF was after 15 min of reperfusion between 20 and 100 ml/min/100 g. After 30 min we got values of 100-200 ml/min/100 g. The V02/min, which was in the control kidneys between 5-6 ml/min/100 g, was about 2 ml/min/100 g.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Post-ischemic renal function after kidney protection with the HTK-solution of Bretschneider.

The cardioplegic solution HTK of Bretschneider was used for canine kidney protection. The kidneys were perfused with this solution for 6-10 min prior to the induction of ischemia. The kidneys were left in-situ for 60, 90, 120 and 135 min ischemia time at a temperature of 25-34 degrees C (n = 13). As a control group we used unilateral nephrectomized dogs (n = 9). After unilateral nephrectomy an elevated plasma creatinine in comparison to preoperative values was observed. After 60 and 90 min under HTK-protection the postoperative plasma creatinine was not elevated compared to the control group. After 120 min of ischemia creatinine level was slightly increased to an average of 2.1 mg% on the first and second postoperative day. These experiments indicate the protective effect of the cardioplegic solution for canine kidney preservation in situ.

Animals↗

PubMed1985

Construction and experimental application of a catheter for selective arterial kidney perfusion in situ.

In order to improve dog kidney perfusion in situ with a protective solution, a perfusion catheter was constructed which allowed continuous pressure measurement in the center of the catheter tip during perfusion. Using this catheter, the equilibration of the extracellular space with a protective solution (HTK solution) was found to be pressure dependent. Continuous pressure and resistance control is therefore a prerequisite for reliable organ protection.

Animals↗

PubMed1985

Effects of preservation conditions and temperature on tissue acidification in canine kidneys.

The influence of temperature (5, 15, 25, and 35 degrees C) on the degree of tissue acidification was examined using 74 canine kidneys with simple ischemia or after protection of the kidneys with Euro-Collins solution or with the HTK-solution of Bretschneider. At an incubation temperature of 5 degrees C, the intrarenal pH value in HTK-protected kidneys is continuously higher than 7.3 during 36 hr of ischemia. In Euro-Collins kidneys the pH value decreases to a pH of 6.4 during this time. In simple ischemic kidneys pH is 6.3 after 36 hr. At 15 degrees C the pH value falls to a lower level in Euro-Collins kidneys than in purely ischemic kidneys, but the pH in HTK-protected kidneys is higher than 6.9 for 24 hr. At 25 degrees C, and especially at 35 degrees C the intrarenal acidosis in Euro-Collins kidneys is much stronger than in unprotected kidneys, and the pH in HTK-protected kidneys does not decrease below 6.7. The lactate production in simple ischemic kidneys and in HTK-protected kidneys is nearly the same (80-100 mumol/gdw), although Euro-Collins kidneys have a steeper increase and reach higher lactate levels (330 mumol/gdw). The HTK solution guarantees satisfactory protection against damaging acidosis over the whole temperature range (5-35 degrees C), but the Euro-Collins solution leads to a stronger and more dangerous acidosis the higher the temperature.

Acidosis↗

PubMedDate not supplied

Detection of renal ischemic lesions using Gd-DTPA enhanced turbo FLASH MRI: experimental and clinical results.

PURPOSE: Our goal was to investigate the role of Gd-DTPA-enhanced dynamic MRI in the evaluation of renal ischemic lesions. METHOD: With a turbo FLASH sequence before and after injection of Gd-DTPA, nine foxhound dogs after 60-120 min of renal ischemia underwent MR examination. In addition, five patients with a tumor in a solitary kidney were examined before and after nephron-sparing renal surgery to evaluate renal perfusion and function. The experimental and clinical findings were correlated with conventional measurements of kidney function and with histological findings. RESULTS: Complete renal ischemia leads to a poor corticomedullary differentiation in Gd-DTPA-enhanced turbo FLASH MRI. The signal-intensity-versus-time plots of kidneys with significant postischemic changes show a less steep increase of signal intensity in the cortex and a steeper increase of signal intensity in the medulla than those of normal kidneys. CONCLUSION: Dynamic MRI demonstrate renal morphology and reflect the functional status of renal vasculature.

Aged↗

PubMedDate not supplied

Quantification by competitive quantitative RT-PCR of VEGF121 and VEGF165 in renal cell carcinoma.

The field of angiogenesis and its mediators in tumour tissue is gaining more and more interest because of their therapeutic implications to arrest progressive growth and metastasis. We examined the expression status of the proangiogenic vascular endothelial growth factor (VEGF) in tumour tissue and adjacent tumour-free tissue from renal cell carcinoma (RCC) as well as in cell cultures deriving from tumour tissue. Quantification of both secreted isoforms ot VEGF by competitive RT-PCR revealed a marked increase of VEGF message in tumours and especially in cell cultures from RCC. We found a significant correlation of VEGF expression and microvessel density which was investigated immunohistochemically. As further compared to other urological neoplasms we investigated for VEGF mediated vascularization, RCC is the most promising candidate for anti-angiogenic therapies.

Carcinoma, Renal Cell↗