Michael S. Maddux

Prevention of Acute Graft Rejection by the Prostaglandin E1 Analogue Misoprostol in Renal-Transplant Recipients Treated with Cyclosporine and Prednisone

Prostaglandins of the E series have been shown to have immunosuppressive properties. To study the effects of the prostaglandin E1 analogue misoprostol on renal function and graft rejection after transplantation, we conducted a randomized, double-blind, placebo-controlled trial in 77 renal-allograft recipients. The subjects received misoprostol (200 micrograms four times daily by mouth; n = 38) or placebo (n = 39) for the first 12 weeks after transplantation, in addition to standard immunosuppression with cyclosporine and prednisone. They were then observed for an additional four weeks after the drug or placebo was discontinued. Treatment with misoprostol was associated with a significant improvement in renal function as judged by the mean (+/- SEM) serum creatinine concentration (128 +/- 7 vs. 158 +/- 11 mumol per liter after 12 weeks; P = 0.03) and creatinine clearance (84 +/- 6 vs. 69 +/- 5 ml per minute per 1.73 m2 of body-surface area; P = 0.05). There was a significant reduction in the incidence of acute rejection in the group treated with misoprostol as compared with the placebo group (10 of 38 vs. 20 of 39; P = 0.02), and there was less need for rehospitalization after transplantation (4 +/- 1 days with misoprostol vs. 10 +/- 2 days for placebo; P = 0.03). Although blood levels of cyclosporine did not differ significantly between the groups, they tended to be higher in the misoprostol group, as did the incidence of acute nephrotoxicity due to cyclosporine (13 of 38 vs. 8 of 39). Infectious complications tended to be fewer in the misoprostol-treated group (14 of 38 vs. 21 of 39). We conclude that misoprostol improves renal function and safely reduces the incidence of acute rejection in renal-transplant recipients treated concurrently with cyclosporine and prednisone.

The Natural History of and Therapy for Perirenal Fluid Collections Following Renal Transplantation

Fluid collections following renal transplantation are not rare and may be associated with serious complications. We studied the incidence, clinical features, pathology and treatment outcome of perirenal fluid collections after kidney transplantation. Between January 1977 and June 1985, 386 consecutive renal transplants were performed at our university. All allografts were studied with B-mode ultrasonography together with a renal scan in the immediate post-transplant period, at 6-month intervals or when clinically indicated. Symptomatic fluid collections, those associated with rejection episodes and those containing more than 50 to 100 ml. fluid were aspirated under sonographic control via aseptic techniques. There were 190 fluid collections (49 per cent) observed during followup (2 to 11 years). Of these collections 98 (51 per cent) were estimated to be less than 50 ml. in volume, were clinically insignificant and resulted in no morbidity. A total of 92 collections was aspirated with 1 aspiration being diagnostic and therapeutic in 57 instances (serous or serosanguinous fluid). The 35 collections remaining were revealed to be lymphoceles on biochemical grounds. Of 13 lymphoceles associated with rejection episodes 8 resolved on initial aspiration. Of the recurrent lymph collections 27 were treated with repeated aspiration, tetracycline sclerotherapy or an operation (10 were treated with marsupialization into the peritoneal cavity). No large collections of urine or blood were detected and 1 infected lymphocele required external drainage. No renal allograft was lost as a result of a fluid collection and over-all graft survival was not affected by the development of perirenal fluid collections. We conclude that perirenal fluid collections are detected commonly in the post-transplant period using B-mode ultrasonography. The majority of these collections are small and will require careful observation only or they will resolve with a single aspiration. Aggressive diagnostic and therapeutic measures are used only for those collections that are symptomatic or result in allograft dysfunction. A rational approach to the diagnosis and treatment of peritransplant fluid collections is described in the form of an algorithm.

A randomized double-blind trial of the use of human recombinant superoxide dismutase in renal transplantation

Oxygen free radical generation has been implicated as a possible mediator of the reperfusion injury postulated to occur following revascularization of the cold preserved and transplanted kidney. The superoxide radical (O2—) scavenger, superoxide dismutase, from bovine or recombinant (rh-SOD) sources, may ameliorate oxygen-free-radical mediated reperfusion injury of transplanted kidneys. To test this hypothesis, we performed a prospective, randomized, double-blind trial of the use of human rh-SOD in renal transplantation at three participating centers. Half of a 20 mg/kg solution of rh-SOD or placebo was administered as a bolus intravenous injection immediately prior to renal allograft reperfusion and the remainder as a peripheral intravenous infusion for 1 hr thereafter. Posttransplant renal function was determined using 99Tc-DTPA clearance to measure glomerular filtration rate at 48±24 hr and day 6 post-transplant. A two-tailed t test was used for pooled data, and analysis of variance was used to evaluate between center differences in outcome. One hundred and sixteen patients (58 rh-SOD and 58 placebo) were entered into the study. No adverse reactions to rh-SOD or placebo were noted. No differences were noted between rh-SOD and placebo groups with regard to GFR at 48 hr, serum creatinine or creatinine clearance at day 6, or percentage of patients with GFR ×10 ml/min or ×5 ml/min at 48 hr. The data did not vary when analyzed by center or in aggregate form, and no correlation was noted between storage time and GFR in either group. We conclude that data from this trial provide little basis for the use of rh-SOD as described to ameliorate reperfusion injury in transplanted kidneys.

The immunosuppressive properties of new oral prostaglandin E1 analogs

Prostaglandins play an important role in cell-mediated immune responses. Their clinical use has been limited by poor oral bioavailability, short half-lives, and significant toxicity profiles. We studied the immunosuppressive properties of new, synthetic, prostaglandin E1 (PGE1) methyl ester analogs (misoprostol, enisoprost) with oral bioavailability using an allogeneic in vitro immunoassay. Our results show that the PGE1 analogs suppress alloproliferative responses and supplement the immunosuppressive activity of cyclosporine and methylprednisolone. Moreover, we demonstrate that addition of recombinant interleukin-2 to the PGE1 analogs restores alloimmune responsiveness and the expression of surface class II antigen and IL-2 receptors on responder lymphocytes. These studies, together with preliminary in vivo data in rodents and man, suggest that the new synthetic oral PGE1 analogs may provide therapeutic efficacy in clinical transplantation and a variety of immunologically mediated diseases.

Effects of ß‐Lactamase‐Mediated Antimicrobial Resistance: The Role of ß‐Lactamase Inhibitors

Production of ß‐lactamase is the most common mechanism of bacterial resistance to ß‐lactam antibiotics. Virtually all bacteria have the capability of synthesizing the enzyme. Microorganisms may already possess the native genetic information necessary for ß‐lactamase production (i.e., chromosomal), or may acquire the capacity by transfer of DNA from another organism (i.e., plasmid‐mediated). The level of ß‐lactamase production may be stable and noninducible (constitutive enzyme production), or may be stimulated on exposure to selected ß‐lactam antibiotics (inducible enzyme production). Inhibitors such as clavulanic acid and sulbactam prevent antibiotic degradation by the ß‐lactamases of many clinically significant pathogens. Therefore, currently available ß‐lactam‐ß‐lactamase‐inhibitor combinations exhibit broad spectra of in vitro activity. Ticarcillin‐clavulanate possesses clinically significant activity against many bacteria, including streptococci, Staphylococcus aureus, Bacteroides fragilis, and numerous Enterobacteriaceae. Amoxicillin‐clavulanate and ampicillin‐sulbactam demonstrate clinically significant activity against streptococci (including enterococci), S. aureus, B. fragilis, and some Enterobacteriaceae. Ticarcillin‐clavulanate is indicated for treatment of serious infections, including septicemia. Amoxicillin‐clavulanate is useful in the treatment of upper respiratory, urinary tract, and skin and soft tissue infections. Ampicillin‐sulbactam may be used for treatment of intraabdominal, gynecologic, urinary tract, and skin and soft tissue infections.

Digoxin‐Like Immunoreactive Substance in Renal Transplant Patients

Digoxin‐like immunoreactive substance (DLIS) has been detected in several patient populations that were not receiving digoxin, including those patients with end‐stage renal disease. The structure and physiologic significance of this compound are unknown, and the fate of DLIS after renal transplantation has not been studied. The authors prospectively evaluated 163 patients (not receiving digoxin) before and after transplantation for the presence of DLIS. Three different assays were used: radioimmunoassay (RIA), affinity mediated immunoassay (ACA), and fluorescence polarization immunoassay (TDX I). Depending on the assay method used, 11% (RIA), 6% (ACA), and 9% (TDX) of patients had detectable DLIS pretransplant. Using all 3 assays, a total of 34 patients (21%) were found to have DLIS. The mean serum digoxin concentration was 0.41 ± 0.13 ng/mL (range: 0.2–1.2 ng/mL) and DLIS was detectable by > 1 assay method in seven patients. DLIS persisted longer in patients who had delayed allograft function (13.7 ± 7 days) than in those who did not (3 ± 1.9 days), P <.05. In summary, detection of DLIS in renal transplant recipients appears to be an infrequent occurrence when using a single digoxin assay method. When detected, the concentration of DLIS is often below the usual therapeutic range for digoxin and disappears once allograft function is established. The authors conclude that the presence of DLIS is unlikely to be clinically significant in the renal transplant population.