Synthesis of shock proteins in cultured fetal mouse myocardial cells

Maternal, foetal and child consequences of immunosuppressive drugs during pregnancy in women with organ transplant: a review

Although pregnancy remains exceptional in women after heart, liver or lung transplant, obstetricians and nephrologists are regularly confronted with pregnancy in renal transplant recipients. National and international registries have described the epidemiology of maternal, foetal and neonatal complications, and transplantation societies have published recommendations on the monitoring of these high-risk pregnancies. In this review, we summarize the existing data on maternal and foetal complications of pregnancies in women after renal transplant, especially the management of immunosuppression. We also describe the few available data on the middle- and long-term outcomes of their children who were exposed in utero to immunosuppressive drugs.

Effects of broad band electromagnetic fields on HSP70 expression and ischemia-reperfusion in rat hearts

Although exposure to broad band (0.2-20 MHz) electromagnetic fields (EMF) is part of the treatment of several diseases, little is known as to their effects on myocardial protein expression and resistance to ischemia-reperfusion (I/R). We exposed Sprague-Dawley rats to either high (H, 10 min/day at 200 V/m, 36.1 microT) or low (L, 2 min/day at 30 V/m, 11.4 microT) intensity broad band EMF for 15 days. At the end of the treatment, myocardial HSP70 was 32 +/- 8% (mean +/- SEM) higher in L (P = 0.01) than in control (C), whereas in H it remained the same as in C. Electron microscopy revealed sporadic ruptures of mitochondrial cristae in H hearts, with no differences in other parameters. Malondialdehyde was increased in treated hearts (P < 0.05), but especially in H (P = 0.008). To assess the protective role of HSP70 during I/R, hearts were Langendorff-perfused with Krebs-Henseleit. After I/R, C hearts displayed depressed rate. pressure (-13 +/- 7%) and increased end-diastolic (+9.2 +/- 2.8 mmHg) and perfusion pressures (+30 +/- 10 mmHg). In H and L, rate. pressure recovery was similar to C (-2 +/- 21% and -12 +/- 16%, respectively, P = NS). In contrast, both end-diastolic and perfusion pressures were higher in L than in H (30.8 +/- 5.4 vs 18.2 +/- 3.5, P = 0.01, and 54 +/- 8 vs 21 +/- 8 mmHg, P = 0.01, respectively) indicating diastolic derangement in L. In conclusion, the effects of broad band EMF on HSP70 appear to be biphasic, and HSP70 overexpression might not be directly related to improved protection against I/R.

Hypothermic preservation of hepatocytes

This paper presents a review of recent research on the hypothermic storage of hepatocytes. The first focus is on the diversity of methodologies currently employed in this area. The cell damage caused by hypothermic preservation and its possible mechanism are then investigated on both morphological and molecular biology. Later, the gene expressions on a mRNA level or enzyme level after hypothermic preservation are further discussed. Finally, the improvement of hypothermic storage by preconditioning, such as by increasing temperature, is explored.

Feasibility of photopheresis to reduce the occurrence of restenosis after percutaneous transluminal coronary angioplasty: a clinical pilot study

BACKGROUND

Photopheresis was evaluated as a means of preventing restenosis on the basis of immune modulation.

METHODS

This was a prospective, randomized, controlled clinical trial analyzing clinical restenosis at 6 months after percutaneous transluminal coronary angioplasty (PTCA). Seventy-eight patients with single-vessel angioplasty were randomly assigned to a control group of 41 patients and a treatment group of 37 patients. At 6 months, there were 72 evaluable patients: 39 control patients and 33 treated. Twenty-nine control patients received balloon PTCA only and 10 patients received stents. Twenty treated patients received PTCA only and 13 patients received stents. Baseline clinical characteristics of both groups were similar. The treatment group received photopheresis for a total of 5 treatments. Primary end points were death from any cause, myocardial infarction, ischemia, and repeat revascularization procedures.

RESULTS

By intention-to-treat analysis, clinical restenosis occurred in 27% of control patients versus 8% of treated patients (P =.040, relative risk = 0.30).

CONCLUSIONS

Photopheresis therapy in patients undergoing balloon PTCA with and without stent deployment has been shown to be effective in reducing restenosis. The use of photopheresis in such patients merits further investigation.

Delayed preconditioning with adenosine is mediated by opening of ATP-sensitive K(+) channels in rabbit heart

The adenosine agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA) induces delayed ischemic protection in vivo. We hypothesized that this protection is mediated by opening of ATP-sensitive K(+) (K(ATP)) channels and increased synthesis of 72-kDa heat shock protein (HSP 72). Six groups (n = 9-13 animals/group) of animals were studied: group I, control rabbits that received no treatment; group II, animals given glibenclamide (0.3 mg/kg iv) 30 min before ischemia; group III, animals given 5-hydroxydecanoate (5-HD; 5 mg/kg iv) 15 min before ischemia; group IV, rabbits treated with CCPA (0.1 mg/kg iv) 24 h before ischemia; and groups V and VI, CCPA-treated animals that received the K(ATP)-channel blockers glibenclamide or 5-HD, respectively, 30 or 15 min before ischemia. All animals were subjected to ischemia by 30 min of coronary artery occlusion followed by 3 h of reperfusion. Risk area was delineated by injection of 10% Evans blue dye, and infarct size was determined by triphenyltetrazolium staining. Action potential duration (APD) was measured with an epicardial electrode. HSP 72 was measured by Western blotting. CCPA caused a significant reduction in infarct size [12.02 +/- 1.0 vs. 40.0 +/- 3.8% (%area at risk) in controls, P < 0.01] that was blocked by glibenclamide (36.2 +/- 3.1%, P < 0.01) and 5-HD (35.0 +/- 2.9%, P < 0.01). Glibenclamide and 5-HD did not change infarct size in control rabbits. These blockers significantly suppressed ischemia-induced APD shortening in control and CCPA-treated animals. CCPA treatment did not induce HSP 72 in hearts. These data suggest that adenosine-initiated delayed protection is mediated via opening of K(ATP) channels but does not involve the synthesis of HSP 72.

Free radicals, calcium homeostasis, heat shock proteins, and myocardial stunning

Repeated brief ischemic episodes result in prolonged depression of contractile function despite the absence of irreversible damage, a phenomenon called myocardial stunning. Considerable evidence exists to suggest that oxygen radicals, particularly the hydroxyl radical formed as a result of Fenton reaction or nitric oxide-peroxynitrite pathway, may contribute to the pathogenesis of myocardial stunning. The generation of free radicals may cause sarcoplasmic reticulum dysfunction, and both of these mechanisms may lead to calcium overload, which in turn could exacerbate the damage initiated by oxygen radicals. Antioxidant therapy has been shown to effectively attenuate or even prevent the development of prolonged depression of contractility in many studies. In addition, preconditioning with brief ischemic insults is able to trigger protection, which appears to attenuate stunning 24 to 48 hours later. The mechanism of this protection is not known, although one or more members of the heat shock protein family may have a role in protection against stunning.

Induction by prostaglandin A1 of haem oxygenase in myoblastic cells: an effect independent of expression of the 70 kDa heat shock protein

Prostaglandins of the A type (PGA) induce the synthesis of 70 kDa heat shock proteins (hsp70) in a large variety of mammalian cells. Induction of hsp70 has been associated with a cytoprotective effect of PGA1 after virus infection or thermal injury. In the present report we provide evidence that, in murine myoblasts, PGA1 is not able to induce hsp70 expression, whereas it increases the synthesis of the constitutive protein, hsc70, and dramatically induces the synthesis of a 32 kDa protein (p32). The p32 protein has been identified as haem oxygenase. PGA1 acts at the transcriptional level by inducing haem oxygenase mRNA synthesis, and the signal for induction appears to be associated with decreased intracellular GSH levels. Haem oxygenase, a low-molecular-mass stress protein induced in mammalian cells by oxidant stress, is known to be part of a general inducible antioxidant defence pathway. The fact that prostaglandin synthesis is stimulated in muscle during contraction and in the heart in response to ischaemia raises the possibility that induction of haem oxygenase by PGA in myoblasts could be part of a protective mechanisms in operation during stress and hypoxia.

Cocultures of fetal and adult cardiomyocytes yield rhythmically beating rod shaped heart cells from adult rats

Different models of isolated cardiomyocytes are generally used for biochemical, biophysical, and pharmacological studies. Fetal cardiomyocytes can be easily cultured for several weeks regaining their ability for rhythmical and synchronous contractions. For investigations, differentiated myocytes derived from adult hearts are closer to the in situ situation. Unfortunately, these cells at best exhibit irregular and asynchronous contractions at very low frequencies. Already 1 d after seeding calcium-tolerant rod-shaped adult cardiomyocytes on a suitable substrate, the differentiated cells begin to dedifferentiate forming a confluent monolayer. After 7-10 d their beating activities are like those of fetal cells. Therefore, we tried to combine the advantages of both cell types to achieve fully differentiated cardiomyocytes, rod-shaped and rhythmically beating, isolated from adult hearts. Using contractile fetal cells as a substrate for the adult cardiomyocytes, freshly seeded differentiated adult myocytes are paced by the contraction frequency of the fetal monolayer. As a consequence, the rod-shaped adult cardiomyocytes reach frequencies of more than 140 cycles/min without external electrical stimulation. This model enables us to study cardiomyocytes in a state very similar to the in situ situation with respect to morphology, integrity, and contractile behavior.

Myocardial protection after whole body heat stress in the rabbit is dependent on metabolic substrate and is related to the amount of the inducible 70-kD heat stress protein

The aims of this study were to examine the effects of whole body heat stress and subsequent stress protein induction on glycolytic metabolism, mitochondrial metabolism, and calcium handling within the heart. The effect of heat stress on glycolytic and mitochondrial pathways was examined by measuring contractile performance in the presence of glucose and pyruvate, respectively. Calcium handling was assessed using force-interval relationships. Right ventricular papillary muscles taken from heat-stressed and control rabbit hearts were superfused with Kreb's solution containing either glucose or pyruvate and rendered hypoxic for 30 min. After reoxygenation, the greatest recovery of contractile function occurred in the heat-stressed muscles with pyruvate as substrate; there was, however, no difference in the force-interval relationship between the groups. The degree of contractile recovery was related to the content of the inducible 70-kD but not the 65-kD, heat stress protein. This study suggests that heat stress enhances the ability of rabbit papillary muscle to use pyruvate, but not glucose, after reoxygenation, and that the differences seen in contractility may be secondary to induction of the 72-kD stress protein.

Hyperthermia induces expression of transforming growth factor-beta s in rat cardiac cells in vitro and in vivo

Hyperthermia causes changes in expression of TGF-beta mRNA and protein in cultured cardiac cells, as well as in the heart in vivo. 12 h after hyperthermia, primary cultures of neonatal rat cardiomyocytes show a two- to threefold decreased expression of TGF-beta mRNAs which returns to control levels by 48 h after heat shock. In cultures of cardiac fibroblasts, expression of TGF-beta mRNAs increases 5-25-fold, 12-48 h after heat shock, while fetal bovine heart endothelial cells show little change in TGF-beta expression after hyperthermia. In each case, mRNAs for TGF-beta s 1, 2, and 3 are regulated similarly. Hearts isolated from rats exposed to hyperthermia show an initial 20-fold decrease in TGF-beta 1 and 3 mRNA levels which return to control levels by 24 h and subsequently are elevated two- to threefold above normal 48-72 h after heat shock; there is little change in TGF-beta 2 mRNA. Expression of immunoreactive TGF-beta 1 and 3 protein, localized intracellularly in myocytes, follows the same pattern as the mRNA expression. By 72 h, some myocytes show hyperstaining for TGF-beta 1. Staining for extracellular TGF-beta 1/3 exhibits the opposite time course, being most intense 3-6 h after heat shock and returning to control levels by 48 h. The increase in TGF-beta s after hyperthermia could play a role in mediating the reported cardioprotective effects of heat shock.

A cell culture assay for the detection of cardiotoxicity

An important step in minimizing the number of animal experiments in medical research is the study of in vitro model systems. We propose the use of "shock protein" formation, which is a cellular response to cell-damaging stress as an assay to monitor cardiotoxicity. Isolated and cultured cardiac myocytes were prepared by a trypsin digestion method from 18-day-old fetal mice. These cells respond to typical substances inducing "shock protein" formation in other cellular systems as well as to known cardiotoxins with the de novo synthesis of "shock proteins." Pharmaceuticals relevant in transplant medicine were tested for possible cardiotoxic effects: Cyclosporine A evokes "shock protein" formation at subtherapeutic concentrations. Azathioprine and methyl-prednisolone exert the same effect but at concentration ranges highly above the therapeutic level. The ability to induce "shock protein" synthesis obviously seems to be restricted to toxic drugs. The data presented demonstrate that the proposed in vitro model system for cardiotoxicity is animal saving and sensitive.