Parasitic infection in renal transplant recipients.

The purpose of this study was to evaluate the prevalence of symptomatic parasitic infections in adult renal transplant recipients. We retrospectively analyzed a sample of 657 adult renal transplant recipients performed from January 2001 to December 2005 for immunosuppression protocol, clinical manifestations, parasite diagnosis, treatments, and outcomes. The prevalence of symptomatic parasitosis infections was 2.4% (16/657). None of the infected patients received cyclosporine in their immunosuppression protocol. Most of the infections were caused by Strongyloids stercoralis (n = 11), followed by Giardia lamblia (n = 3), Toxoplasma gondii (n = 1), and Trypanosoma cruzi: (n = 1). Strongyloides stercoralis was the most frequent agent, causing three cases of hyperinfection including one fatal case. With the new immunosuppressive regimes there must be a suspicion of parasitic infection to avoid the diagnostic delay that can be fatal. Strategies, including empiric treatment for S. stercoralis, must be considered.

Expanding criteria for the use of living donors: what are the limits?

The cadaver organ shortage has pushed the transplant community to extend the boundaries beyond the traditional criteria used for living donor transplantation. This new liberal policy involves: (1) the type of donor, such as emotionally related individuals, the direct or indirect interchange of donors, anonymous as well as rewarded donation; (2) challenging immunological criteria, using incompatible ABO blood types and or transplantation across a positive cross-match; (3) relaxing clinical criteria related to elderly, hypertensive, or obese donors, or patients with nephrolithiasis, fibromuscular renal artery disease, hematuria, or renal cell carcinomas. However, these practices may be dangerous. They must be clearly validated to promote a liberal policy of donor acceptance since it may carry a risk for both the donor and the recipient as well as for society. It is crucial to ensure the physical integrity of the donor as well as to provide guarantees, for instance a 1-year policy of life insurance, an indefinite long-term medical follow-up and the assurance of going to the top of the waiting list if the donor becomes uremic in the future.

Pregnancy outcome after renal transplantation.

AIMS: The aim of our study was to evaluate the frequency and the outcome of pregnancies in renal transplant recipients at our center. METHODS: This study involved the retrospective analysis of 405 childbearing female renal recipients for presence of risk factors, the outcome of pregnancy, and maternal and fetal complications. RESULTS: Fourty-four pregnancies occurred in 41 patients (10.8%). Mean age at transplantation was 23.6 +/- 6.3 years (range, 12-38 years). Only in 5 pregnancies were there no risk factors. In 13 (29.5%) pregnancies, the previous creatinine level was >1.5 mg/dL, in 16 (36.45%), proteinuria was >500 mg/24 hours; 29 (65.9%) were hypertensive; 14 (31.8%) had a time between transplantation and pregnancy less than 2 years (mean time, 35.5 +/- 30.9 months; range, 3-120 months). The outcomes were 27 (61.4%; 11 term and 16 premature delivery) successful pregnancies, 6 (13.6%) spontaneous abortions, 10 (22.7%) therapeutic abortions, and 1 (3.2%) fetal death. Pre-eclampsia occurred in 9 (20.4%) pregnancies and eclampsia in 1 (2.2%). The mean weight of the offspring was 2195 +/- 490 g (range, 1300- 2980 g). There were 2 cases of acute fetal distress and 1 oligodramnios. Median creatinine level was 1.0 (range, 0.4-3.0) mg/dL before conception and 1.2 (range, 0.7-9.0) mg/dL 6 month after pregnancy (P <.001). The long-term patient and graft survival rates were similar for pregnant versus nonpregnant recipients in the childbearing age. CONCLUSION: Most pregnancies were successful, although the premature delivery rate was high (36.4%). Only 5 conceptions occurred in the absence of risk factors. Pregnancy did not impair the patient and graft survival during long-term follow-up.

Immunosuppression in pancreas transplantation: mycophenolate mofetil versus sirolimus.

The use of mycophenolate mofetil (MMF) in pancreas transplantation has increased graft survival and decreased the incidence of acute rejections episodes (ARE), regardless of the choice of calcineurin inhibitor. The combination of MMF with tacrolimus (TAC) is the most common protocol, it is considered the gold standard for new protocols. In the last few years, there have been reports of a small number of patients treated with sirolimus (RAPA), usually combined with TAC. Patient and pancreas survival rates as well as the incidence of ARE were similar to protocols with TAC and MMF. Twenty simultaneous pancreas and kidney (SPK) transplantations were performed using an immunosuppressive protocol of TAC, RAPA, and steroids (STE) after 2000. The incidence of ARE was 25%; all episodes responded to STE. Only 2 patients (10%) displayed hypercholesterolemia requiring treatment with statins. The use of RAPA as an alternative to MMF is promising, although presently one with limited experience. The combination of MMF and RAPA with or without a calcineurin inhibitor is an option to be evaluated in the future.

Systemic titanium levels in rabbits with a titanium implant in the absence of wear.

All non-noble metals and alloys will release metallic species into the body. This raises the issue of amount and fate, i.e. transport and storage, of these metal dissolution products. For titanium, the nature and extent of these systemic effects remain mostly unknown. In this study we investigated titanium levels in alleged target tissues in rabbits, both with and without a titanium implant functioning in the absence of wear, and compare these results to the limited body of literature concerning systemic levels of titanium. Titanium fibre felts were implanted into the tibia of rabbits. At various time points, lung, spleen, and muscle samples were collected from these rabbits as well as two groups of control rabbits. The samples were analysed for titanium concentration using electrothermal atomic absorption spectrophotometry. The data for the implant groups show that titanium levels in these tissues do not increase in comparison with controls up to 1 y after implantation.

Titanium serum and urine levels in rabbits with a titanium implant in the absence of wear.

Although devices made of titanium and its alloy with 6% aluminium and 4% vanadium have been remarkably successful primarily in orthopaedic and dental applications, clinical reports have implicated the biological response to released metal from this class of metals as a cause of failure. It is our hypothesis that in the absence of wear, the amount of titanium released is small and will preferentially accumulate in local tissues. One important implication of this is that measurable quantities of titanium in serum and urine that have been observed in clinical studies result from mechanically induced or assisted release phenomena. In order to test this hypothesis, titanium levels in various tissues and fluids of animals both with and without titanium implants need to be determined. In this paper, we report the titanium concentration in serum and urine of rabbits in the absence of wear. Titanium fibre felts were implanted into the tibia of rabbits. At various time points, serum and urine samples were collected from these rabbits as well as from two groups of control rabbits. The samples were analysed for titanium concentration using electrothermal atomic absorption spectrophotometry. The data for the implant group show that titanium levels in serum and urine do not increase in comparison to controls up to one year after implantation. Some clinical studies have documented elevated titanium serum and urine levels in the presence of titanium-based prostheses. The different results from these studies can be resolved by considering titanium release mechanisms other than passive dissolution.

Local accumulation of titanium released from a titanium implant in the absence of wear.

Titanium and its alloys, like the majority of metallic implant materials, release passive metal dissolution products. This raises the issues of amount and fate, i.e. transport, storage, and/or excretion of these metal dissolution products. In this paper we document titanium levels in tissues local to a commercially pure titanium implant in the absence of wear; compare these values to control tissues; and determine the relative contribution of the local accumulation to total release. Titanium fiber felts were implanted into the tibia of rabbits for periods up to 1 year. Bone and muscle tissue samples near the implant were collected. Using electrothermal atomic absorption spectrophotometry the samples were analyzed for titanium content. Compared to controls, titanium levels in the bone near the implant were elevated at 1-, 4-, and 12-month postoperative time points. The 12-month time point had higher periprosthetic bone titanium levels than both the 1- and the 4-month implant groups. Titanium levels in muscle tissue near the felt also indicated release was occurring. The data support the hypothesis that metal species released from titanium implants in the absence of wear have a limited solubility. As a result, they tend to remain in an area local to the implant.

Crystal structure of the surface oxide layer on titanium and its changes arising from immersion.

The passivating surface oxide on titanium is one of the elements considered in the explanation of the favorable biologic response of this metal in implant applications. In the present study, transmission electron microscopy was used to identify the crystal structure and morphology of the oxide film on commercially pure titanium specimens before and after immersion in simulated physiologic fluids. The results show that the oxide layer is composed mainly of anatase and rutile, both of which are tetragonal in structure. Although the simulated physiologic fluids did not induce an observable change in the crystal structure for the immersion times investigated, the results indicate an immersion-induced change in microstructure from a fine-grained to a coarser-grained structure. The grain growth observed could be attributed to the growth of the native oxide crystals; however, it most likely results from the formation of a new oxide layer. The results also support oxide thickening as one of the processes associated with passive dissolution of titanium.

Bone tissue growth enhancement by calcium phosphate coatings on porous titanium alloys: the effect of shielding metal dissolution product.

The possible mechanism of minimization of prosthesis-derived bone growth inhibitors by shielding of the metal and the reduction, if not elimination, of the associated metal dissolution was investigated. Titanium, aluminium and vanadium release rates were determined in vitro for Ti alloy specimens both with and without a calcium phosphate coating. Ti orderly oriented wire mesh (OOWM) porous coatings on Ti-6Al-4V substrates were used as the metal specimens. Half of the specimens were coated with a 75 microns calcium phosphate ceramic (CPC coating). Seven reference (OOWM) and seven coated (OOWM-CPC) specimens were immersed and placed along with seven control solutions for various periods in an incubator maintained at 37 degrees C and 5% CO2 - air atmosphere. Whereas the reference solutions showed a Ti release increasing as a function of time, the solutions that had the CPC-coated specimens contained no measurable amounts of titanium. The Al in solution around the CPC-coated specimens was significantly greater than the concentration around non-coated specimens. The Al, however, did not increase significantly with time, at least up to 4 wk immersion. The ceramic coating had a small beneficial effect on V concentration. In the absence of a significant adverse effect of Ti on local bone tissue formation, we focus on the Al data of our study. The possible adverse effect of this element is well documented. The calcium phosphate coating produced a significant increase of biological fixation, yet at the same time a greater Al release into solution, calling into question the significance of CPC coating in shielding adverse metal passive dissolution to explain enhanced bone growth [corrected].

[Cinedensitometric documentation of a catheter-induced spasm in the carotid siphon (author's transl)]. / Cinedensitometrische Dokumentation eines katheterinduzierten Gefässspasmus im Carotissiphon.

During a transfemoral cerebral angiography spasm of the carotid siphon was to be observed. This circulatory disturbance has been recorded by angiocinematography and evaluated by cinedensitometry. The analysis of the catheter-induced spasm is intended as a contribution to the etiology and the pathophysiology of vasospasm in man.