Long-term outcome after switch from cyclosporine-based triple-drug immunosuppression to double therapy at three months

Cyclosporin A (CyA) together with steroids and azathioprine (Aza) has been successfully used for prophylactic immunosuppression in numerous recipients of kidney allografts. The aim of this study was to evaluate the long-term effect of reducing this initial triple-drug therapy to double-drug therapy at 3 months. One hundred consecutive recipients of a cadaveric renal allograft with stable and good graft function were randomly allocated to continue with CyA and steroids (group 1) or CyA and Aza (group 2). Both groups were comparable with regard to all relevant patient characteristics. After a mean observation period of 55 (26-76) months no significant difference was observed in the incidence of acute rejection episodes after conversion (4 in group 1 and 5 in group 2), or in the incidence of graft loss (4 in group 1 and 5 in group 2); all graft rejection episodes were easily reversed with steroid pulses and patients switched back to triple-drug therapy. Patient survival was 94% in group 1 and 100% in group 2 at 55 months. In group 1, however, a higher number of viral infections and steroid-related side effects was noted. From these data it is concluded that initial triple-drug therapy can safety be reduced to a CyA-based double-drug combination after 3 months in renal allograft recipients with stable function. The combination with Aza is recommended because of its fewer side effects.

T cells from rejected human kidney allografts respond to heat shock protein 72

The immune response to heat shock proteins (hsps) is gaining more and more interest. Members of the 65 and the 70 kDa hsp families have been shown to be target molecules of the immune system in autoimmune diseases, in cancer immunity and recently in the rejection of rat heart allografts. It was therefore the aim of the present study to investigate whether T cells propagated from two rejected human renal allografts also recognised hsps. In vivo activated interleukin-2 (IL-2) receptor positive T cells were expanded from renal allografts, which had been removed because of irreversible rejection, by 1 week of culture in IL-2 only, followed by stimulation with OKT-3 in combination with IL-2. One T cell line was obtained from each graft. FACS analysis of the lines demonstrated that 51% and 53% of the cells were CD4+ and 45% and 42% CD8+; 4% and 5% were gamma delta + T cells. Both lines had a significant proliferative response when stimulated with recombinant human hsp 72. In contrast, hsp 65 did not induce stimulation. The lines also showed a proliferative response upon stimulation with epithelial kidney cells, purified and cultured from the respective rejected kidneys. These results demonstrate that T cells propagated from rejected human kidney allografts recognize hsp 72. This suggests that hsp-specific T cells may play a role in the rejection process of allograft kidneys.

Control of mitochondrial and cellular respiration by oxygen

Control and regulation of mitochondrial and cellular respiration by oxygen is discussed with three aims: (1) A review of intracellular oxygen levels and gradients, particularly in heart, emphasizes the dominance of extracellular oxygen gradients. Intracellular oxygen pressure, pO2, is low, typically one to two orders of magnitude below incubation conditions used routinely for the study of respiratory control in isolated mitochondria. The pO2 range of respiratory control by oxygen overlaps with cellular oxygen profiles, indicating the significance of pO2 in actual metabolic regulation. (2) A methodologically detailed discussion of high-resolution respirometry is necessary for the controversial topic of respiratory control by oxygen, since the risk of methodological artefact is closely connected with far-reaching theoretical implications. Instrumental and analytical errors may mask effects of energetic state and partially explain the divergent views on the regulatory role of intracellular pO2. Oxygen pressure for half-maximum respiration, p50, in isolated mitochondria at state 4 was 0.025 kPa (0.2 Torr; 0.3 microM O2), whereas p50 in endothelial cells was 0.06-0.08 kPa (0.5 Torr). (3) A model derived from the thermodynamics of irreversible processes was developed which quantitatively accounts for near-hyperbolic flux/pO2 relations in isolated mitochondria. The apparent p50 is a function of redox potential and protonmotive force. The protonmotive force collapses after uncoupling and consequently causes a decrease in p50. Whereas it is becoming accepted that flux control is shared by several enzymes, insufficient attention is paid to the notion of complementary kinetic and thermodynamic flux control mechanisms.

Autoantibodies to Auerbach's plexus in achalasia

Achalasia is a motor disorder of the oesopagus characterized by decrease in ganglion cell density in Auerbach's plexus. The cause of the lesion is unknown. This is to repeat on the occurrence of autoimmune phenomena in patients with achalasia, in particular circulating antibodies against Auerbach's plexus and its possible meaning. IgG-antibodies against Auerbach's plexus were determined by standard indirect immunofluorescence. Antibodies to the cytoplasm of Auerbach's plexus were found in 37 of 58 patients with achalasia at variable stages of the disease (I-IV) with a disease duration ranging from 1 to 20 years but only in 4 out of 54 healthy controls (specificity 93%, sensitivity 64%, p < 0.0001), and in none of 12 patients with Hirschsprung's disease as well as 12 patients with cancer of oesophagus and only in one of 11 patients with peptic oesophagitis as well as in one of 13 patients with myasthenia gravis. The present observations suggest that autoimmunity to Auerbach's plexus plays a role in the pathogenesis of achalasia, the mechanism of action is unknown.

Protective effects of various preservation solutions on cultured endothelial cells

Vascular endothelium represents the first target in organ preservation and plays an important role in reperfusion injury. Bovine aortic endothelial cells were cultivated and the most commonly used preservation solutions, such as University of Wisconsin HTK (Brettschneider's histidine-tryptophane-ketoglutarate), and Euro-Collins solutions were tested on the endothelial monolayer. In addition, one group of cultivated cells was preserved with cold saline solution, and endothelial monolayers grown in culture medium were used as controls. The quality of preservation was assessed after 24, 48, and 72 hours of cold storage. Reperfusion was simulated and its effects were observed by reincubation in culture medium at 37 degrees C for 6 hours. The total number of cells, cell viability (determined using trypan blue exclusion), and morphologic alterations were determined. Prostacyclin release was evaluated as a biochemical marker. University of Wisconsin solution maintains more than 99% cell viability after rewarming after both 24 and 48 hours of cold storage. After 72 hours, 86.7% of cells were still viable. Preservation with HTK and Euro-Collins solution allowed cell survival for only 24 hours (96.7%, HTK; 49.9%, Euro-Collins), with no viable cells seen after 48 hours. The cold saline-preserved sample showed 57.8% viable cells after 24 hours and 29.7% after 48 hours. No viable cells were detectable after 72 hours. Light microscopy revealed several patterns of both structural damage and intracellular change (nucleus and cytoplasm) in the endothelial monolayer after preservation with HTK, Euro-Collins solution, and cold saline solution. No morphologic alterations were seen in the University of Wisconsin solution group for as long as 72 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

[Proven indication for manometry and pH determination of the esophagus]

Manometry and pH-metry are essential in the examination of functional disturbances of the esophagus. Before they are used, morphological lesions have to be excluded. Proven indications for functional methods are symptoms which cannot be clarified otherwise. Indications for manometry are: dysphagia of unknown origin, noncardiac chest pain and necessary preoperative studies. Indications for long-term pH-metry are: atypical reflux symptoms, (in particular chronic respiratory disease), noncardiac chest pain, atypical esophagitis and preoperative examination prior to antireflux surgery. Used critically, manometry and pH-metry can be very helpful as cost-effective diagnostic tools.

Clinical in vitro endothelialization of femoropopliteal bypass grafts: an actuarial follow-up over three years

PURPOSE

The creation of an endothelial coverage on prosthetic vascular surfaces may improve the performance of synthetic small diameter vascular grafts. In vitro lining with cultured autologous endothelial cells offers a confluent endothelium at the time of implantation.

METHODS

Between June 1989 and December 1991, 49 patients who had no saphenous vein available entered the study. Indication for operation was disabling claudication in 37 patients and critical ischemia in 12 patients. With a random 1:2 assignment, 33 patients were admitted to the endothelialized group and 16 control patients received an untreated polytetrafluoroethylene prosthesis. Cultured autologous endothelial cells from the external jugular vein were confluently lined onto polytetrafluoroethylene grafts precoated with fibrinolytically inhibited fibrin glue. The follow-up was based on angiography, platelet labeling studies with indium 111-labeled oxine, assessment of the ankle-brachial index, and duplex sonography.

RESULTS

First-passage mass cultures of 16 million endothelial cells-required for the confluent lining of a 70 cm long 6 mm graft-were reached 25.1 +/- 11.2 days after vein excision. Growth failure occurred in 27.3%. After 32 months, the actuarial patency was 84.7% for endothelialized grafts and 55.4% for control grafts (p < 0.041 by Breslow test; p < 0.068 by Mantel-Cox test). The ankle-brachial index was continually diverging, reaching significantly lower values in the control group at 24 months (0.98 +/- 0.14 in the endothelialized group versus 0.70 +/- 0.12 in the control; p < 0.0023). The uptake of indium 111-labeled platelets--measured at 9 days, 3 months, 6 months, and 12 months--was significantly lower in the endothelialized group during the entire observation period.

In vitro endothelialization of a mesosystemic shunt: a clinical case report

The existence of a confluently covering endothelium that is free of any thrombotic appositions can be proved 30 days after clinical implantation of an in vitro endothelialized expanded polytetrafluoroethylene graft. The recipient of the mesosystemic H-graft was a 69-year-old man who had a thrombosed portal vein following pancreatitis. Autologous endothelial cells were obtained from the external jugular vein under local anesthesia, applying the in situ cannulation technique. After low-density plating, first-passage mass cultures of 1.22 x 10(6) endothelial cells were obtained 14 days after vein excision. After precoating was accomplished with fibrinolytically inhibited fibrin glue, a 10 mm expanded polytetrafluoroethylene graft was confluently lined with the autologous endothelial cells at a seeding density of 1.2 x 10(5) cells/cm2. After a maturation period of an additional 9 days and the microbiologic exclusion of a possible infection, an 11 cm graft segment was implanted between the superior mesenteric vein and the inferior vena cava. In spite of a patent shunt the patient had a repeat bleeding episode, needed parenteral nutrition, and died of sepsis on day 30. Immediately after the graft had been taken out, specimens were processed by scanning electron microscopy and light microscopy for the immunohistochemical proof of the endothelial nature of the surface-covering cell layer. The entire graft surface displayed a confluent cell lining that was free of any thrombotic appositions. A strongly positive stain result for both factor VIII-related antigen and the fixation-resistant CD34 molecule identified these cells as endothelial. No alpha-actin-positive cells could be detected. The underlying protein matrix was well preserved and unaltered in thickness and appearance, compared with preimplantation samples. None of the specimens showed any evidence of infection. This human demonstration of an intact endothelium on a patent venous prosthesis further establishes in vitro lining as a method that actually creates a persistent and functioning endothelium on a synthetic graft surface.

Effect of galanin on food intake in rats: involvement of lateral and ventromedial hypothalamic sites

Galanin has previously been reported to elicit feeding in satiated animals when injected into the hypothalamic paraventricular nucleus. It is not known, however, 1) whether this action is due to activation of feeding signals or suppression of satiety signals or both or 2) whether other hypothalamic regions such as the lateral hypothalamus (LH) or the ventromedial hypothalamus (VMH) are involved in this action. The effects of galanin on food intake were therefore examined in satiated and in fasted rats both after intracerebroventricular injection (0.1, 1, and 10 micrograms/10 microliters) and after microinjection (1 and 5 micrograms/0.5 microliters) into the LH and VMH. Twenty minutes after intracerebroventricular injection, galanin significantly and dose dependently augmented food intake by up to sevenfold in freely feeding rats and by up to 79% in fasted animals. The galanin-induced augmentation of cumulative food intake up to 2 h after injection was due to the initial increase in food consumption during the 0 to 20-min interval. This suggests that galanin acts by activation of feeding behavior and not by suppression of satiety signals in these fasted animals, in which satiety signals are presumably not initially operative. Twenty minutes after intrahypothalamic injections into both the LH and VMH, galanin (5 micrograms) significantly increased food consumption, fivefold in freely feeding rats and 30-35% in fasted rats. Thus stimulation of feeding by centrally injected galanin also involves loci within the LH and VMH.

Experimental in vitro endothelialization of cardiac valve leaflets

This study reports our results with vitro endothelialization of fresh nonpreserved homograft valve leaflets compared with mild alternatively preserved valves and valves treated by preservation procedures commonly used for commercially available tissue valves. In vitro lining of biological heart valves with cultured autologous endothelial cells might help prevent the detrimental effects of degeneration on valve durability. To investigate the growth characteristics of endothelial cells on valve bioprostheses, three different methods of storage and preservation were compared. After precoating with fibronectin and seeding of 4.4 x 10(4) endothelial cells/cm2 onto the different leaflet surfaces, primary adherence, growth kinetics, morphology, and maintenance of monolayer integrity were studied over a period of 10 days. On valve leaflet surfaces of group 1 (fresh nonpreserved homograft valve leaflets) and group 2 (mild alternatively preserved valves), endothelial cells grew to persistent monolayers between days 6 and 10. In contrast, endothelial cell proliferation with monolayer growth could not be achieved on the group 3 leaflets (preserved like commercially available biological valve prostheses). In that group, no viable endothelial cells could be found on the valve surfaces 2 days after seeding. These results demonstrate the theoretical feasibility of endothelializing biological heart valve leaflets in vitro if they are not preserved and stored according to commonly used procedures. Provided such an endothelium can withstand the mechanical forces after implantation in vivo, in vitro endothelialization might contribute either to the development of new biological heart valves for modern cardiac surgery or to the improvement of clinical results with homograft valve transplants.

Growth properties of cultured human endothelial cells on differently coated artificial heart materials

The cultivation of autologous endothelial cells on the blood surface of artificial hearts might prevent their detrimental thromboembolic complications. To investigate the growth characteristics of endothelial cells on theoretically suitable biomaterials, we compared three polyurethanes (Pellethane, Biomer, Enka) and three silicone rubbers (Elastosil, 3145 RTV, Medical Adhesive). All synthetic surfaces were precoated with an extracellular matrix (group 1), fibronectin (group 2), or a glutaraldehyde-preserved cellular matrix (group 3). After the seeding of 2.5 x 10(4)/cm2 human endothelial cells into the various surfaces, primary adherence, growth kinetics, and maintenance of monolayer integrity were studied for 13 days. On the three polyurethanes all precoating procedures resulted in endothelial cell proliferation and the formation of persistent monolayers. In contrast, on silicone rubbers a persistent coverage with a confluent endothelium could be achieved only on the glutaraldehyde-preserved cellular matrix. When endothelial cell growth was quantitatively assessed on all precoating substrates, the glutaraldehyde-preserved cellular matrix proved to be far superior on each of the synthetics (p less than 0.001). These results demonstrate the theoretical feasibility of endothelialization of artificial hearts in vitro. Provided such an endothelium can withstand the mechanical forces within an artificial heart, in vitro endothelialization might contribute to a regained attractiveness of the elective long-term implantation of artificial hearts.