Regeneration of functional nerves within full thickness collagen-phosphorylcholine corneal substitute implants in guinea pigs

Our objective was to evaluate promotion of tissue and nerve regeneration by extracellular matrix (ECM) mimics, using corneal implantation as a model system. Porcine type I collagen and 2-methacryloyloxyethyl phosphorylcholine (MPC) were crosslinked using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) and moulded into appropriate corneal dimensions to serve as substitutes for natural corneal ECM. These were implanted as full thickness grafts by penetrating keratoplasty into the corneas of guinea pigs after removal of the host tissue, and tracked over eight months, by clinical examination, slit-lamp biomicroscopy, and esthesiometry. Histopathology and ex vivo nerve terminal impulse recordings were performed at three months and at eight months. The implants promoted regeneration of corneal cells, nerves and the tear film, while retaining optical clarity. After three months, electrophysiological recordings showed evidence of mechano-nociceptors, and polymodal units inside the implants, while cold-sensitive units were present only on the peripheral host cornea. Following eight months, the incidence of nerve activity and the frequency of spontaneous firing were higher than in control eyes as reported for regenerating fibers. Active cold nerve terminals also innervated the implant area. We show that ECM mimetic materials can promote regeneration of corneal cells and functional nerves. The simplicity in fabrication and demonstrated functionality shows potential for ECM substitutes in future clinical applications.

Effect of elective coronary angiography on glomerular filtration rate in patients with advanced chronic kidney disease

BACKGROUND AND OBJECTIVES

Preemptive transplantation is ideal for patients with advanced chronic kidney disease (CKD). The practice has been to perform coronary angiography (CA) on all patients aged >50, all diabetics, and all patients with cardiac symptoms or disease with a view to revascularization before transplantation. Historically patients have delayed CA until established on renal replacement therapy due to concerns of precipitating the need for chronic dialysis. The objectives of this study were to establish the risk of contrast nephropathy in patients with advanced CKD who undergo screening CA, and to determine whether or not preemptive transplantation is achievable.

DESIGN AND SETTING

This retrospective analysis included 482 patients with stage IV/V CKD seen in West London predialysis clinics from 2004 to 2007. Seventy-six of 482 (15.8%) patients considered as potential transplant recipients met the authors' criteria for coronary angiography. Modification of Diet in Renal Disease (MDRD) GFR measurements were recorded for the 12 mo preceding and 12 mo following CA unless a defined endpoint was reached (transplantation, dialysis, or death).

RESULTS

Mean MDRD GFR at CA was 12.51 +/- 3.51 ml/min. The trend was not significantly different 6 mo pre- and postangiography. Cumulative dialysis-free survival was 89.1% 6 mo postangiography. Twenty-three of 76 (30.3%) patients had flow-limiting coronary artery disease. Twenty-five of 76 (32.9%) patients underwent transplantation with 22 of 25 (88.0%) transplants being performed preemptively.

CONCLUSIONS

The data suggest CA screening does not accelerate the decline in renal function for patients with advanced CKD, facilitating a safe preemptive transplant program.

Optimal neural differentiation and extension of hybrid neuroblastoma cells (NDC) for nerve-target evaluations using a multifactorial approach

In vitro models of tissues, such as the cornea, represent systems for modeling cell-to-cell interactions and tissue function. The objective of this study was to develop an optimized nerve differentiation medium to incorporate into a 3D in vitro model to study innervation and cell targeting. A hybrid neuroblastoma cell line (NDC) was examined for its ability to differentiate into neurons, produce neurites, and functionally contact target cells. Neuronal differentiation of NDCs was optimized through a combinatorial approach which involved culturing cells in the presence of various extracellular matrices and soluble factors. A serum-free medium containing nerve growth factor (NGF), dimethyl sulfoxide (DMSO), or dexamethasone resulted in the greatest proportion of NDCs demonstrating a neuronal morphology. Similarly, with supplementation of cyclic AMP (cAMP) or NGF, neurite extension was optimized. Combining these factors generated an optimized differentiation and extension medium, relative to the individual components alone. In co-culture with epithelial cells, NDC neurites generated in the optimized medium formed contacts with epithelial targets and produced substance P. Similarly, NDCs seeded into a collagen matrix produced neurites that projected through the matrix to target epithelial cells, promoted epithelial stratification, and increased the rate of epithelial wound healing. As well, differentiated NDCs could target and alter acetylcholine receptor clustering in mouse C2C12 myotubes, demonstrating synaptic plasticity. Our data supports the use of NDCs, in combination with optimized medium, for generating an innervated in vitro model.

Rituximab is an effective treatment for lupus nephritis and allows a reduction in maintenance steroids

BACKGROUND

Lupus nephritis is a life-threatening complication of SLE. Treatment regimes include steroids and cyclophosphamide, both associated with significant morbidity. Newer regimes include mycophenolate mofetil (MMF). We report our outcomes in a prospectively monitored cohort of patients receiving our new standard treatment protocol, comprising rituximab induction therapy and MMF maintenance in patients already taking maintenance immunosuppression for SLE who developed lupus nephritis. We then attempted steroid reduction/withdrawal.

METHODS

Patients with class III/IV/V lupus nephritis were included. All patients were on steroids prior to the development of lupus nephritis. Eighteen patients have reached at least 1 year follow-up. These patients received rituximab induction therapy and MMF maintenance therapy. Steroid reduction/withdrawal was guided by clinical response.

RESULTS

Fourteen of 18 (78%) patients achieved complete or partial remission with a sustained response of 12/18 (67%) at 1 year, with 2 patients having a relapse of proteinuria. Four patients did not respond. There was a significant decrease in proteinuria from a mean protein:creatinine ratio (PCR) of 325 mg/mmol at presentation to 132 mg/mmol at 1 year (P = 0.004). Serum albumin significantly increased from a mean of 29 g/L at presentation to 34 g/L at 1 year (P = 0.001). The complication rate was low with no severe infections. Following treatment with rituximab, 6 patients stopped prednisolone, 6 patients reduced their maintenance dose and 6 patients remained on the same dose (maximum 10 mg).

CONCLUSION

This data demonstrates the efficacy of a rituximab and MMF based regime in the treatment of lupus nephritis, allowing a reduction or total withdrawal of corticosteroids.

Sodium citrate versus heparin catheter locks for cuffed central venous catheters: a single-center randomized controlled trial

BACKGROUND

Sodium citrate has antibacterial and anticoagulant properties that are confined to the catheter when used as a catheter lock. Studies of its use as a catheter lock have suggested its efficacy in preventing infection and bleeding complications compared with sodium heparin.

STUDY DESIGN

Open-label randomized controlled trial of 2 catheter locks to examine the hypothesis that sodium citrate catheter locks will reduce catheter-related bacteremia and exit-site infection.

SETTINGS & PARTICIPANTS

232 consenting long-term hemodialysis patients in 4 satellite dialysis units to a large dialysis program with protocolized treatment and targets. All patients were using twin-catheter single-lumen Tesio-Caths (MedComp, Harleysville, PA).

INTERVENTION

6 months' use of 46.7% sodium citrate (citrate) or 5% heparin (heparin) locked postdialysis in the dead space of the central venous catheter.

OUTCOMES & MEASUREMENTS

Primary end point of catheter-related bacteremia and exit-site infection. Secondary end points of catheter thrombosis defined by the use of urokinase lock and infusion, new catheter insertion, catheter-related admission, blood transfusions, parenteral iron, and erythropoietin requirements.

RESULTS

Catheter-related bacteremia did not differ in the 2 groups, with an incidence of 0.7 events/1,000 catheter-days. There was no significant difference in rates of exit-site infection (0.7 versus 0.5 events/1,000 catheter-days; P = 0.5). The secondary end point of catheter thrombosis defined by the use of a urokinase lock was significantly more common in the citrate group, with an incidence of 8 versus 4.3/1,000 catheter-days (P < 0.001). Other secondary end points did not differ. Citrate treatment was curtailed compared with heparin because of a greater incidence of adverse events, with a mean treatment duration before withdrawal of 4.8 +/- 2.0 versus 5.7 +/- 1.2 months, respectively (P < 0.001).

LIMITATIONS

Low baseline catheter-related bacteremia and exit-site infection event rates may have underpowered this study. High adverse-event rates may have been related to high-concentration citrate that led to increased overspill and reduction in lock volume. This may also explain the increased rates of thrombosis in this group.

CONCLUSION

Widespread and long-term use of 46.7% citrate catheter locks with Tesio-Cath access is not justified by this study.

Making the most of routine data in palliative care research--a case study analysis of linked hospital and mortality data on cancer and heart failure patients in Scotland and Oxford

The research base of palliative care is growing rapidly, but despite methodological advances, some of the practical challenges of working with people at the end of life will persist. This means that analysis of routine data is arguably more important in studying palliative care than it is in other aspects of health services research. End-of-life researchers have been using the high-quality linked data from cancer registries for many years. This paper explores the value of a less well-known resource for palliative care research: linked mortality and hospital activity data. Two case studies are presented using information from Scotland (population 5.1 million) and the former Oxford region of England (population 2.5 million). The advantages and limitations of linked hospital and mortality data for research and service planning in palliative care are drawn out through analyses investigating hospital bed utilisation by people with cancer and heart failure and the influence of social deprivation on the use of hospital services in the last year of life. The use of such data deserves a higher profile.

Prevalence of gastrointestinal bacterial pathogens in a population of zoo animals

Faecal prevalence of gastrointestinal bacterial pathogens, including Campylobacter, Escherichia coli O157:H7, Salmonella, Shigella, Yersinia, as well as Arcobacter, were examined in 317 faecal specimens from 44 animal species in Belfast Zoological Gardens, during July-September 2006. Thermophilic campylobacters including Campylobacter jejuni, Campylobacter coli and Campylobacter lari, were the most frequently isolated pathogens, where members of this genus were isolated from 11 animal species (11 of 44; 25%). Yersinia spp. were isolated from seven animal species (seven of 44; 15.9%) and included, Yersinia enterocolitica (five of seven isolates; 71.4%) and one isolate each of Yersinia frederiksenii and Yersinia kristensenii. Only one isolate of Salmonella was obtained throughout the entire study, which was an isolate of Salmonella dublin (O 1,9,12: H g, p), originating from tiger faeces after enrichment. None of the animal species found in public contact areas of the zoo were positive for any gastrointestinal bacterial pathogens. Also, water from the lake in the centre of the grounds, was examined for the same bacterial pathogens and was found to contain C. jejuni. This study is the first report on the isolation of a number of important bacterial pathogens from a variety of novel host species, C. jejuni from the red kangaroo (Macropus rufus), C. lari from a maned wolf (Chrysocyon brachyurus), Y. kristensenii from a vicugna (Vicugna vicugna) and Y. enterocolitica from a maned wolf and red panda (Ailurus fulgens). In conclusion, this study demonstrated that the faeces of animals in public contact areas of the zoo were not positive for the bacterial gastrointestinal pathogens examined. This is reassuring for the public health of visitors, particularly children, who enjoy this educational and recreational resource.

Impact of whole genome amplification on analysis of copy number variants

Large-scale copy number variants (CNVs) have recently been recognized to play a role in human genome variation and disease. Approaches for analysis of CNVs in small samples such as microdissected tissues can be confounded by limited amounts of material. To facilitate analyses of such samples, whole genome amplification (WGA) techniques were developed. In this study, we explored the impact of Phi29 multiple-strand displacement amplification on detection of CNVs using oligonucleotide arrays. We extracted DNA from fresh frozen lymph node samples and used this for amplification and analysis on the Affymetrix Mapping 500k SNP array platform. We demonstrated that the WGA procedure introduces hundreds of potentially confounding CNV artifacts that can obscure detection of bona fide variants. Our analysis indicates that many artifacts are reproducible, and may correlate with proximity to chromosome ends and GC content. Pair-wise comparison of amplified products considerably reduced the number of apparent artifacts and partially restored the ability to detect real CNVs. Our results suggest WGA material may be appropriate for copy number analysis when amplified samples are compared to similarly amplified samples and that only the CNVs with the greatest significance values detected by such comparisons are likely to be representative of the unamplified samples.

Differentiation of a fibrin gel encapsulated chondrogenic cell line

Hyaline cartilage has very limited regenerative capacity following damage. Therefore engineered tissue substitutes have been the focus of much research. Our objective was to develop a fibrin-based scaffold as a cell delivery vehicle and template for hyaline cartilage regeneration, and compare its cellular properties against monolayer and pellet culture for chondrogenic cells. The chondrogenic precursor cell line, RCJ 3.1C5.18 (C5.18), was chosen as a test system for evaluating the effect of various culture conditions, including cell encapsulation, on articular chondrogenic cell differentiation. The C5.18 cells in monolayer showed elevated expression of collagen II, an articular chondrogenic marker, but also markers for fibrocartilage differentiation (collagen I and versican) when cultured with chondrogenic medium as compared to basic maintenance medium. Pellets of C5.18 cells cultured in chondrogenic medium were histologically more organized in structure than pellets cultured in control maintenance medium. The chondrogenic medium cultured pellets also secreted an extracellular matrix that was comprised of type II with very little type I collagen, indicating a trend towards a more hyaline-like cartilage. Moreover, when cultured in chondrogenic medium, fibrin-encapsulated C5.18 cells elaborated an extracellular matrix containing type II collagen, as well as aggrecan, which are both components of hyaline cartilage. This indicated a more articular-like chondrogenic differentiation for fibrin encapsulated C5.18 cells. The results of these experiments provide evidence that the C5.18 cell line can be used as a tool to evaluate potential scaffolds for articular cartilage tissue engineering.

Promotion of angiogenesis in tissue engineering: developing multicellular matrices with multiple capacities

One of the aims of tissue engineering is to be able to develop multi-tissue organs in the future. This requires the optimization of conditions for the differentiation of multiple cell types and maintenance of the differentiated phenotype within complex engineered tissues. The goal of this study was to develop prototype tissue engineered matrices to support the simultaneous growth of different cell types with a particular focus on the angiogenic process. We examined two different matrix compositions for the promotion of blood vessel and tube formation. A fibrin-based matrix with the addition of a combination of growth factors supported vascular growth and the invasion of inflammatory cells. Using this fibrin matrix, in combination with a collagen-based hydrogel, a simple in vitro model of the cornea with adjacent sclera was developed that was complete with innervation and vascular structures. In addition, we showed that collagen-based matrices were effective in delivering mononuclear endothelial progenitor cells to ischemic tissue in vivo, and allowing these cells to incorporate into vascular structures. It is anticipated that with further development, these matrices have potential for use as delivery matrices for cell transplantation and for in vitro study purposes of multiple cell types.

The Magnitude and Time Course of Changes in Mycophenolic Acid 12-Hour Predose Levels During Antibiotic Therapy in Mycophenolate Mofetil-Based Renal Transplantation

There is increasing evidence that monitoring predose plasma levels of mycophenolic acid (MPA) is of benefit in renal transplant recipients treated with mycophenolate mofetil (MMF). Concomitant treatment with oral antibiotics leads to a 10% to 30% reduction in MPA area under the curve (AUC)0-12, probably by reducing enterohepatic recirculation (EHR). Because of the timing of EHR (6 to 12 hours postdose), the magnitude of predose MPA level reduction may be disproportionately larger than that of AUC0-12. However, changes in predose MPA levels and the time course over which these changes occur and resolve during antibiotic treatment have not been studied. The purpose of this study was to define the extent and time course of MPA predose level reduction during antibiotic therapy. A total of 64 MMF-treated renal transplant recipients (with tacrolimus cotherapy) were prospectively studied. Clinically indicated cotherapy with either oral ciprofloxacin or amoxicillin with clavulanic acid resulted in a reduction in 12 hour predose MPA level to 46% of baseline within 3 days of antibiotic commencement. No demographic or biochemical variables were associated with the magnitude of MPA level reduction. No further fall in MPA level was seen by day 7, but MPA levels recovered spontaneously to 79% of baseline after 14 days of antibiotics. Levels normalized within 3 days of antibiotic cessation. No changes in daily MMF dose (normalized for body weight) were made during antibiotic treatment. This data should help the clinician to recognize the extent of MPA predose level reduction during antibiotic therapy, and to avoid inappropriate MMF dose escalation and potential risk of toxicity.

Introducing mechanical biological waste treatment in South Africa: a comparative study

This paper presents the results of the first pilot project on mechanical biological waste treatment (MBWT) in South Africa. The study has shown that biological waste treatment in windrows using a passive aeration system that utilises thermal convection to drive the aeration process within a windrow of waste is appropriate for South Africa, in relation to low capital costs, low energy inputs, limited plant requirements and potential for labour-intensive operations. The influence of climate, waste composition and operational facilities was evaluated to optimise the treatment technique to local conditions. The maximum temperatures reached during the intensive thermophilic stage were effectively equivalent to the German experience. The lower CO2 production experienced in the South African trials was attributed to a different waste stream (high presence of plastics) due to the absence of a proper source separated waste collection system. An accurate adjustment of the input material (structural matter in particular) to the specific ambient conditions and irrigation during composting should result in higher organic carbon degradation efficiency in equivalent timeframes. This preliminary experience suggests that the applicability of MBWT in emerging countries, such as South Africa, is directly dependant on the mechanical treatment steps, available operational facilities and nature of the input material.

Properties of porcine and recombinant human collagen matrices for optically clear tissue engineering applications

Porcine and recombinant human atelocollagen I solutions were cross-linked with a water soluble carbodiimide at various stoichiometries and collagen concentrations (5-20 w/w %). The resulting hydrogels were clear and, when used as cell growth matrices, allowed cell and nerve visualization in vitro and in vivo. We have previously reported that, after six months of implantation in pigs' and rabbits' corneas, these robust hydrogels allowed regeneration of host cells and nerves to give optically clear corneas with no detected loss in thickness, indicating stable engraftment. Here, the biocompatible hydrogel formulations leading to this novel in vivo performance were characterized for amine consumption, gel hydration, thermal properties, optical clarity, refractive index, nutrient diffusion, biodegradation, tensile measurements, and average pore diameters. Gels with excellent in vitro (epithelial overgrowth, neurite penetration) and in vivo performance (clarity, touch sensitivity regeneration) had 4-11 nm pores, yet had glucose and albumin diffusive coefficients similar to mammalian corneas and allowed neurite extension through the gels.

Determinants of mycophenolic acid levels after renal transplantation

There are data suggesting an association between mycophenolic acid (MPA) levels and acute rejection and toxicity in renal transplant recipients treated with mycophenolate mofetil (MMF), and therefore, knowledge of factors determining MPA levels may aid in accurate adjustment of MMF dosage. A total of 4970 samples taken 12 hours postdose were analyzed for MPA by immunoassay at regular intervals from the first week posttransplantation in 117 renal transplant patients immunosuppressed with MMF and tacrolimus in a steroid-sparing regimen (prednisolone for the first 7 days only). MPA levels rose in the first 3 months and stabilized thereafter; dose-normalized MPA levels rose throughout the first 12 months and subsequently stabilized. Multivariate analysis by means of a population-averaged linear regression showed positive associations between MPA level and total daily dose (P < 0.001) but not individual dose or total daily dose corrected for body weight. Positive associations were also seen with serum albumin (P = 0.01), tacrolimus trough level (P = 0.01), and female gender (P = 0.002). The association with tacrolimus levels diminished with time. Negative associations were seen between MPA level and higher estimated creatinine clearance (P < 0.001), and also with increasing alanine transaminase levels (P = 0.002), the use of oral antibiotics (P < 0.001), and infective diarrhea (P < 0.001). The latter findings may be related to changes in enterohepatic recirculation of MPA. Many clinical variables show associations with trough MPA levels. An understanding of these factors may aid therapeutic monitoring of MMF.

Clinical Outcomes of Renal Transplantation Using Liquid Chromatographic Monitoring of Tacrolimus

It is suggested that specific methods of Tacrolimus monitoring rather than immunoassays which over-estimate Tacrolimus levels, should be used in transplant recipients. There is limited data, however, comparing clinical outcomes of renal transplantation using each of these techniques. In this study, 40 renal transplant recipients with Tacrolimus monitoring by Microparticle Enzyme Immunoassay (MEIA; target trough level 10-15 ng/ml) were compared with 40 patients monitored by High Performance Liquid Chromatography with Tandem Mass Spectrometry (HPLC-MS; target trough level 8-13 ng/ml). All received anti CD25 antibody induction and Mycophenolate Mofetil in a steroid sparing protocol. No demographic differences were seen between MEIA and HPLC-MS groups. All patients were followed for 6 months. Patient survival was 100% in both groups; graft survival was 100% in the MEIA group and 97.5% in the HPLC-MS group. The groups did not differ in the number of dose changes required in the first 6 months or in the number of patients displaying Tacrolimus levels within target range at three and six months. Delayed graft function occurred in 14 patients in the MEIA group and 12 patients in the HPLC-MS group (P = NS). Biopsy-proven acute rejection occurred in 4 patients in the MEIA group and 1 patient in the HPLC-MS group (P = 0.17). Biopsy proven acute Tacrolimus nephrotoxicity occurred in 6 patients in the MEIA group, and 7 in the HPLC-MS group (P = NS). No difference was seen in serum creatinine or estimated creatinine clearance at 3 or 6 months. No difference between groups was seen in systolic or diastolic blood pressure, or total cholesterol at 3 or 6 months. 2 patients in the MEIA group developed CMV disease and 1 developed posttransplantation diabetes mellitus. CMV and posttransplantation diabetes were not seen in the HPLC-MS group. 2 patients in each group developed reversible tremor. This study suggests that renal transplantation with HPLC-MS monitoring of Tacrolimus is safe and effective.

Five years of steroid sparing in renal transplantation with tacrolimus and mycophenolate mofetil

Steroid sparing with tacrolimus and mycophenolate mofetil (MMF) is associated with good short-term renal transplant outcomes. However, late allograft dysfunction and failure remain concerns. In this study, 101 consecutive patients underwent renal transplantation with tacrolimus, MMF, and 7 days of corticosteroids only. After a median follow-up of 51 months (range 36-62), overall patient survival is 97%, and overall survival with graft function is 91%. The acute rejection rate at 12 months was 19%. Late rejection was uncommon, with only three further episodes beyond 12 months. Graft function was stable during the study, with a mean creatinine of 140 micromol/L and mean estimated creatinine clearance of 57 ml/min at the end of follow-up. Six patients developed posttransplant diabetes mellitus (three cases beyond 12 months). This steroid avoidance regimen is associated with excellent medium-term patient and graft outcomes, and a low incidence of side effects.

Mycophenolic acid 12-h trough level monitoring in renal transplantation: association with acute rejection and toxicity

Studies of renal transplantation utilizing trough plasma level monitoring of mycophenolic acid (MPA) have shown inconsistent associations with toxicity and rejection. In this study, 5600 12-h trough MPA samples from 121 renal transplant recipients immunosuppressed with mycophenolate mofetil (MMF) and tacrolimus in a steroid sparing protocol (steroids for 7 days only) were sequentially analyzed. Higher MPA levels were associated with lower hemoglobin concentrations and anemia (hemoglobin <10 g/dL). Similarly, higher MPA levels were associated with lower total white cell counts and an increased incidence of leucopenia (total white cell count <4.0 x 10(9)/L). Hypoalbuminemia and renal impairment were also associated with hemotoxicity. MMF-associated diarrhea and viral infection were associated with higher MPA levels. Conversely, biopsy-proven acute rejection within the first month post-transplantation was associated with lower MPA levels. Anti-CD25 antibody induction was also associated with reduced rejection rates. No association was seen between MPA levels and platelet count, thrombocytopenia or bacterial infection. An MPA level of 1.60 mg/L early post-transplantation best discriminated patients with and without rejection, and an MPA level of 2.75 mg/L best discriminated patients with and without toxicity later post-transplantation.

EGF-grafted PDMS surfaces in artificial cornea applications

Lack of epithelial cell coverage has remained a persistent problem in the design of an artificial cornea. In this work, polydimethylsiloxane (PDMS) surfaces were modified with epidermal growth factor (EGF) to improve the growth of corneal epithelial cells. The EGF was covalently tethered to PDMS substrates aminated by plasma polymerization of allylamine via a homobifunctional polyethylene glycol (PEG) spacer. Surface modification was confirmed by contact angle and X-ray photoelectron spectroscopy measurements. By varying the ratio of EGF to PEG from 1:50 to 1:5, EGF amounts from 40 to 90 ng/cm2 could be bound, as determined by surface plasmon resonance (SPR) and 125I radiolabelling. Human corneal epithelial cells on the various modified surfaces were cultured both in the presence and absence of EGF in the culture medium to determine the effect of covalently bound EGF on the cells. The results demonstrated that covalently bound EGF on the surfaces is active with respect to promoting epithelial cell coverage. This was significant when compared to unmodified controls.

Late steroid withdrawal for renal transplant recipients on tacrolimus and MMF is safe

INTRODUCTION

We conducted a study to assess the safety of staged, late steroid withdrawal in kidney or kidney/pancreas transplant recipients on steroids, tacrolimus, and mycophenolate mofetil (MMF).

MATERIALS AND METHODS

We studied 50 patients including 33 recipients of cadaveric kidneys, eight living donor kidneys, and nine kidney-pancreas transplants. The mean time posttransplantation was 5.1 years (range 2.1 to 7.9 years). All patients were induced on prednisolone, tacrolimus, and MMF; steroids were withdrawn over 5 to 6 months. The rate of steroid reduction was altered in the face of typical steroid withdrawal symptoms (limb-girdle arthralgia/myalgia).

RESULTS

No rejection episodes occurred during steroid withdrawal. No patient required transplant biopsy for graft dysfunction. Six patients failed steroid withdrawal: five due to arthralgia/myalgia and one due to recurrent pulmonary sarcoidosis. The unexplained rise in serum creatinine following steroid withdrawal described in several other steroid withdrawal studies was not observed in this patient cohort. The mean serum creatinine was 137 micromol/L with deltacreatinine -6.8 micromol/y per year prior to steroid cessation versus 132 micromol/L with deltacreatinine -5.9 micromol/y in the year post-steroid cessation. There were 14 patients with posttransplant diabetes mellitus in this cohort: eight on gliclazide and six on insulin. We observed a reduction in their daily insulin/gliclazide requirements from 52 units to 41 units, and 73 mg to 65 mg, respectively. Two patients became gliclazide-independent at the time of steroid cessation.

CONCLUSIONS

Careful steroid withdrawal from a platform of tacrolimus and MMF is safe and not associated with a significant risk of rejection or graft dysfunction.

Expressed sequence tags from the Yukon ecotype of Thellungiella reveal that gene expression in response to cold, drought and salinity shows little overlap

Thellungiella salsuginea (also known as T. halophila) is a close relative of Arabidopsis that is very tolerant of drought, freezing, and salinity and may be an appropriate model to identify the molecular mechanisms underlying abiotic stress tolerance in plants. We produced 6578 ESTs, which represented 3628 unique genes (unigenes), from cDNA libraries of cold-, drought-, and salinity-stressed plants from the Yukon ecotype of Thellungiella. Among the unigenes, 94.1% encoded products that were most similar in amino acid sequence to Arabidopsis and 1.5% had no match with a member of the family Brassicaceae. Unigenes from the cold library were more similar to Arabidopsis sequences than either drought- or salinity-induced sequences, indicating that latter responses may be more divergent between Thellungiella and Arabidopsis. Analysis of gene ontology using the best matched Arabidopsis locus showed that the Thellungiella unigenes represented all biological processes and all cellular components, with the highest number of sequences attributed to the chloroplast and mitochondria. Only 140 of the unigenes were found in all three abiotic stress cDNA libraries. Of these common unigenes, 70% have no known function, which demonstrates that Thellungiella can be a rich resource of genetic information about environmental responses. Some of the ESTs in this collection have low sequence similarity with those in Genbank suggesting that they may encode functions that may contribute to Thellungiella's high degree of stress tolerance when compared with Arabidopsis. Moreover, Thellungiella is a closer relative of agriculturally important Brassica spp. than Arabidopsis, which may prove valuable in transferring information to crop improvement programs.

Recruitment of multiple cell lines by collagen-synthetic copolymer matrices in corneal regeneration

Collagen hydrogel matrices with high optical clarity have been developed from collagen I, cross-linked with a copolymer based on N-isopropylacrylamide, acrylic acid and acryloxysuccinimide. The controlled reaction of collagen amine groups with this copolymer under neutral pH and aqueous conditions gave robust, optically clear hydrogels and prevented the excessive collagen fibrillogenesis that can lead to collagen opacity. These sterile, non-cytotoxic hydrogels allowed epithelial cell overgrowth and both stromal cell and nerve neurite ingrowth from the host tissue. This regenerative ability appeared to result from the high glucose permeability, nanoporosity and the presence of cell adhesion factors, RGD in collagen and the laminin pentapeptide, YIGSR, grafted onto the copolymer. Under physiological conditions, optical clarity superior to the human cornea and tensile performance adequate for suturing were obtained from some formulations.

Cytokine Polymorphisms Do Not Influence Acute Rejection in Renal Transplantation Under Tacrolimus-Based Immunosuppression

INTRODUCTION

Acute rejection remains an important cause of graft loss after renal transplantation. It has been suggested that cytokine genotyping may play a predictive role in identifying individuals who are at higher risk of acute rejection with a view to individualizing their immunosuppression. The aim of this study was to investigate any possible associations between acute rejection and certain cytokine polymorphisms.

METHODS

We genotyped 91 cadaveric renal transplant recipients on tacrolimus-based immunosuppression and 84 of their donors. The cytokine polymorphisms studied were the following: tumor necrosis factor (TNF)-alpha-1032 T/C, TNF-alpha-865 C/A, TNF-alpha-859 G/A, interleukin (IL)1-R1-970 C/T, IL-10 haplotype [-1082, -819, -592], and IL-6-174 C/G.

RESULTS

We found no association between any polymorphism and the incidence of acute rejection. This was true for both the recipient and donor population.

CONCLUSION

Cytokine polymorphisms did not influence acute rejection in our study. We conclude that in the modern era of immunosuppression cytokine genotyping is not a significant predictor of acute rejection in renal transplantation.