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Biomedical subjects

J Andres

Publications and source records attributed to J Andres.

At least 37 records · Page 2Linked to original sources
PubMed1997

Clinical and echocardiographical study of the aortic homograft implantations in patients with Marfan syndrome.

The aim of the study was to assess the long-term results of surgical treatment with homogenic aortic grafts (HAGs) implantation in patients with Marfan syndrome. There were 31 patients with Marfan syndrome and aortic aneurysm who were operated on between 1980 and 1996. Aortic dissection was diagnosed in 14 patients, DeBakey Type I in six patients and Type II in eight patients. Four patients had to be operated urgently in cardiogenic shock with cardiac tamponade. Sealing up and reinforcement with strip of felt or Gore-Tex has been applied in 22 patients. The surgical modifications mentioned above have been applied since 1987 in all patients with the diameter of the aortic ring exceeding 30 mm or with active infective endocarditis or during reoperation. In 16 patients the space between the aortic homograft and patients own aortic wall was joined to the right atrial auricle. Patients were followed up for 12-179 months (average: 94.6 +/- 499). Three patients died in the early postoperative period and four patients died in the late postoperative period. Rethoracotomy because of bleeding complications was necessary in five patients. HAG damage was responsible for six other reoperations-new HAGs have been implanted in three patients and artificial prostheses were implanted in the other three patients. In the late follow-up period significant improvement in cardiac performance was observed in 24 patients (NYHA I or II). Survival probability of 15 years for the whole group was 80%. The lowest survival probability has been shown in the group of patients with DeBakey Type I aortic dissection (35% survived 15 years after operation). Echocardiographic follow-up has shown that the pressure gradient in HAG was low (7.4 +/- 6.2 mmHg). Only in two patients did the HAG gradient exceeded 20 mmHg. There were no significant differences concerning aortic ring diameters, dimensions of HAG and echocardiographic parameters between the group with surgical modifications, i.e. sealing up and reinforcement with strip of felt or Gore-Tex applied and the group in which these modifications were not applied. Homogenic aortic graft implantation as a method of surgical treatment of aortic aneurysm in patients with Marfan syndrome avoids postoperative anticoagulation, results in substantial improvement of cardiac performance and prolongs life. Surgical treatment should be considered in asymptomatic patients with large aneurysms (exceeding 55-65 mm) in patients with Marfan syndrome because there is a high risk of death in this group of patients in the case of dissection.

Adolescent↗
PubMed1995

[Cardiac gene expression after brief coronary occlusion].

In the pig short coronary occlusions induce molecular damage on the protein level in the myocardium, which elicit repair mechanisms by increased transcription and translation, including the activation of potential transcription factors (protooncogenes), genes involved in repair processes (heat shock genes) or calcium-binding genes. Additionally, some growth factors like insulin-like growth factor II show increased transcription in accordance with their function as trophic factors for reversibly injured myocardium. Changes in mRNA levels mostly are due to increased transcription rates and rarely due to prolonged half-life of the mRNA. However, at present our data do not allow us to conclude which genes are causative for myocardial stunning and/or ischemic preconditioning.

Animals↗
PubMed1994

Effects of unloaded reperfusion on mitochondrial function in the postischemic myocardium.

The effect of mechanical unloading on recovery of postischemic myocardial performance, high energy phosphate content, and mitochondrial function was tested in an isolated working rabbit heart model. After 30 min of global ischemia, prolonged unloaded reperfusion could prevent complete loss of contractility, deterioration of mitochondrial function, and depletion of the ATP pool as was found when only short-term unloading was performed. Aortic flow recovered to 21% of preischemic control, and left ventricular dP/dt max to 46% (p < 0.05 vs. short-term unloading). OPR and ADP/O stabilized at 42 and 72%, respectively (p < 0.05 vs. short-term unloading), and ATP at 33% of control (p < 0.05 vs. short-term unloading). These results show the beneficial effect of prolonged unloading in postischemic hearts.

Adenosine Triphosphate↗
PubMed1994

Kinetics of extracellular potassium concentration in irradiated red blood cells.

BACKGROUND: Irradiation of cellular blood components prevents onset of transfusion-associated graft-versus-host disease. The present study was designed to monitor the post-irradiation changes of the extracellular potassium concentration in red blood cells (RBC) stored in SAG-M (saline adenine glucose-mannitol), in order to estimate the right time for their prophylactic irradiation and the right span of post-irradiation storage. MATERIALS AND METHODS: Ten units each of fresh, 10 days and more than 20 days stored SAG-M RBCs were divided into 2 equal portions each. One portion was gamma-irradiated with 30 Gy (137Cs-source). Another 10 fresh RBC units were separated, and portions were irradiated with 15, 30, 60 or 120 Gy. The determination of potassium was performed simultaneously in corresponding irradiated and non-irradiated portions; immediately after irradiation, after 1 and 5 days, and every 10 days of additional storage (up to 30 days). All measurements were performed in the cell-free supernatant, using flame emission photometry. RESULTS: The extracellular potassium concentration increased permanently with the duration of storage both in non-irradiated and irradiated specimens. At the end of the period of storage this increase in the irradiated portions was approximately 2 times the potassium concentration of the non-irradiated portions (60 mmol/l vs. 38 mmol/l, p < 0.001). Thereby no significant differences of the potassium efflux rates were estimated at the end of the period of storage between fresh RBCs irradiated and stored RBCs irradiated. The mean 5 days post-irradiation potassium release from fresh RBC units was similar to that in 25-30 days stored non-irradiated portions (34.3 mmol/l vs. 38 mmol/l). The extracellular potassium increase was irradiation dose-dependent (r = 0.89, p < 0.001). CONCLUSIONS: SAG-M RBCs can be irradiated with 30 Gy immediately post-harvest and subsequently stored for a couple of days prior to transfusion without producing critically high extracellular potassium concentrations.

Blood Preservation↗
PubMed1994

["Stunned myocardium"--laboratory curiosity or clinically relevant phenomenon of myocardial failure?].

Reversible contractile dysfunction ("myocardial stunning") now is recognized in laboratory animals as well as in the clinic. The precise mechanism(s) responsible for this transient decrease in myocardial contractility is at present unknown. However substantial body of experimental evidence suggest failure in calcium homeostasis due to free radicals injury and calcium overload in ischemic/reperfused myocardium.

Animals↗
PubMed1994

[Response of cells to stress].

A major question in biology is how cells deal with rapid changes in their environment. Now it is clear that all organisms share a common molecular response that included a rapid synthesis of so called stress proteins. These proteins preserve cells' survival under stress conditions and adapt them to new circumstances.

Adaptation, Physiological↗
PubMed1994

Energetic state of the postischemic myocardium and its relation to contractile failure.

We used the isolated working rabbit heart preparation as a model to study the relationship between postischemic myocardial dysfunction and the energetic state of the heart in terms of mitochondrial function and myocardial high energy phosphate (HEP) contents. Normothermic global myocardial ischemia (10, 20 and 30 min) was induced. Cardiac function, mitochondrial function and myocardial HEP contents were measured. Viability of the postischemic myocardium was assessed by electron microscopy. Myocardial tissue was found to be intact up to 20 min of ischemia plus reperfusion. Areas of irreversibly damaged myocardium were found after 30 min of ischemia. Myocardial contractile function was significantly depressed after 10 and 20 min of ischemia and severely depressed after 30 min of ischemia. Postischemic myocardial dysfunction was associated with normal mitochondrial function and HEP content after 10 min of ischemia, with near-normal mitochondrial function and HEP content after 20 min of ischemia and with pathologic values after 30 min of ischemia. It is concluded that postischemic myocardial stunning is not associated with a disturbance of the energy producing processes. More severe ischemia however leads to progressive deterioration of mitochondrial function which may contribute to complete deterioration of myocardial contractile function upon reperfusion.

Adenosine Triphosphate↗
PubMed1994

[Molecular mechanisms for protecting the heart].

Long lasting myocardial ischemia causes death of myocytes despite the restoration of coronary blood flow. Short period of ischemia and reperfusion transiently injures myocytes and is followed by the prolonged but reversible contractile dysfunction called myocardial stunning. Additionally, after a short time ischemia the postischemic myocardium shows enhanced tolerance towards subsequent, long time ischemia, so called ischemic preconditioning. The mechanisms responsible for both phenomena are not completely understood. Myocardial stunning is probably caused by injury to the heart at the molecular level (for example the transient inactivation or damage of proteins of the sarcoplasmic reticulum or the contractile machinery). Since contractility of stunned myocardium recovers, this injury is reversible. The presence of anti-oxidant enzymes system in the heart as well as endogenous protective substances like adenosine or bradykinin and synthesis of stress proteins like hsp 70, hsp 27 or ubiquitin might represent the molecular defense mechanisms against ischemia/reperfusion injury.

Adenosine↗
PubMed1994

[Expression of heat shock proteins in the normal and acutely stunned myocardium].

The aim was to examine the expression of ubiquitin (Ub), 27 kDa heat shock protein (hsp 27) and hsp 60 mRNA in normal and briefly ischemic and reperfused porcine myocardium. The left anterior descending coronary artery was occluded for two periods of 10 min, separated by 30 min of reperfusion. After the second occlusion the myocardium was reperfused up to 210 min. Tissue from ischemic, ischemic-reperfused and nonischemic regions of the heart were analysed by Northern and slot blot hybridization and nuclear run-on transcription assays employing radiolabelled cDNA probes for Ub, hsp 27 and hsp 60 as well as by Western blot using monoclonal antibodies recognizing Ub protein conjugates and antiserum recognizing hsp 27. Systolic wall thickening was significantly decreased at 30 min reperfusion after both occlusions and remained depressed at longer periods of reperfusion. Using Northern blot hybridizations several mRNAs encoding Ub, 0.9 kb mRNA encoding hsp 27, and 2.2 kb mRNA encoding hsp 60 were detected in sham-operated, nonischemic and ischemic myocardial tissues. Densitometric analysis of Northern and slot blot hybridization signals showed the significant increase of the basal tissue levels of Ub mRNA in stunned regions only during the 30 min of the second reperfusion period. Increased levels of hsp 27 mRNA in stunned tissue were already noted at the first ischemic period and were sustained during the subsequent periods of reperfusion as compared to the control region of the heart. Changes in hsp 60 mRNA tissue levels were not observed during ischemia and subsequent reperfusions. Transcription of the Ub and hsp 27 genes was increased during 30 and 120 min of the second reperfusion period. The transient enhancement of tissue levels of Ub mRNA was associated with the temporary formation of new Ub-protein conjugates. However, the increased synthesis of mRNA encoding hsp 27 was not followed by changes of hsp 27 protein content in the myocardial tissue.

Animals↗
PubMed1993

Improvement of pregnancy rates with oocyte donation in older recipients with the addition of progesterone vaginal suppositories.

Pregnancy rates and implantation rates with oocyte donation in recipients 40 years of age and older were significantly lower than those obtained in recipients under the age of 40. This difference was eliminated when P vaginal suppositories were added to the luteal regimen in older recipients. Our experience suggests that uterine aging may play a role in the successful initiation of a pregnancy, but this may be overcome with the preparation of the uterus with P vaginal suppositories.

Adult↗
PubMed1993

Expression of heat shock proteins in the normal and stunned porcine myocardium.

OBJECTIVE: The aim was to examine the expression of ubiquitin (Ub), 27 kDa heat shock protein (hsp27), and hsp60 mRNA in normal and briefly ischaemic and reperfused porcine myocardium: METHODS: The left anterior descending coronary artery was occluded for two periods of 10 min separated by 30 min of reperfusion. After the second occlusion the myocardium was reperfused up to 210 min. Tissue from ischaemic, ischaemic-reperfused, and non-ischaemic regions of the heart was analysed by northern and slot blot hybridisation and nuclear run-on transcription assays employing radiolabelled cDNA probes for Ub, hsp27, and hsp60, as well as by western blot using monoclonal antibodies recognising Ub protein conjugates and antiserum recognising hsp27. RESULTS: Systolic wall thickening was significantly decreased at 30 min reperfusion after both occlusions and remained depressed at longer periods of reperfusion. Using northern blot hybridizations, several mRNAs encoding Ub, 0.9 kb mRNA encoding hsp27, and 2.2 kb mRNA encoding hsp60 were detected in sham operated, non-ischaemic, and ischaemic myocardial tissues. Densitometric analysis of northern and slot blot hybridisation signals showed significant increase of basal tissue levels of Ub mRNA in stunned regions only during the 30 min of the second reperfusion period. Increased levels of hsp27 mRNA in stunned tissue were already noted at the first ischaemic period and were sustained compared to control during the subsequent periods of reperfusion. Changes in hsp60 mRNA tissue levels were not observed during ischaemia and subsequent reperfusions. Transcription of the Ub and hsp27 genes was increased during 30 and 120 min of the second reperfusion period. The transient enhancement of tissue levels of Ub mRNA was associated with temporary formation of new Ub-protein conjugates. However, the increased synthesis of mRNA encoding hsp27 was not followed by changes of hsp27 protein content in myocardial tissue. CONCLUSIONS: The findings support the hypothesis that molecular damage occurs in stunned myocardium; however, the target molecules remain to be recognised.

Animals↗
PubMed1993

Relationship of the polymerase chain reaction for cytomegalovirus to the development of hepatitis in liver transplant recipients.

In a pilot study, the polymerase chain reaction was found to be more sensitive than standard viral culture methods for the detection of cytomegalovirus, particularly from blood and tissues. We therefore applied this technique to 71 serially collected liver biopsies from 16 orthotopic liver transplant patients. All patients were CMV-seropositive (n = 15) or seroconverted (n = 1). Seven patients (9 biopsies) had histologically proved CMV hepatitis, and all these biopsies were CMV PCR-positive. Six of these 7 patients had a prior liver biopsy that was CMV PCR-positive, but culture and histology-negative, an average of 13.2 +/- 6.9 days before the histologically positive biopsy. The 7th patient was not biopsied prior to the diagnostic biopsy. Three patients had 7 liver biopsies that were CMV PCR-positive, but histologically negative for CMV hepatitis. Two of these three had CMV infection confirmed by viral culture of blood or liver biopsy. The remaining 6 patients had a total of 26 liver biopsies that were negative for CMV by PCR, culture, and histology. Among liver transplant patients, CMV PCR performed on liver biopsy specimens correctly identified all histologically proven cases of CMV hepatitis. CMV PCR positivity in liver tissue did not correlate with latent infection and preceded the development of CMV hepatitis or other meaningful CMV infection in 8 of 10 patients.

Biopsy↗
PubMed1993

Reperfusion after brief repetitive ischemia in porcine myocardium does not alter expression of creatine kinase MM or mitochondrial ATPase mRNAs.

We examined whether the mRNA expression of creatine kinase MM isozyme (CKMM) and mitochondrial F1-ATPase, the key enzymes of intracellular energy transduction, are altered in porcine myocardium subjected to repeated brief periods of ischemia followed by reperfusion. The left anterior descending coronary artery was occluded for two cycles of 10 min with 30 min reperfusion in between, followed by the reperfusion up to 210 min. Systolic wall thickening was significantly decreased at 30 min reperfusion after both occlusions and remained depressed during reperfusion. In Northern blot analysis 1.5 kb CKMM and 1.9 F1-ATPase mRNA species were detected in sham, nonischemic and ischemic myocardial tissues. Densitometric analysis of signals showed a 30% decrease of the CKMM mRNA expression (p < 0.05 as compared to nonischemic area of the same heart and sham operated animals) only during the first period of ischemia. Reperfusion as well as the subsequent period of ischemia did not alter expression of CKMM mRNA. The expression of F1-ATPase mRNA remained unchanged during ischemia and reperfusion. We conclude that reperfusion after brief myocardial ischemia in swine is not associated with changes in CKMM and F1-ATPase mRNA expression. Our findings would support the hypothesis that myocardial stunning is not caused by altered expression of energy transducing enzymes.

Animals↗