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D Taube

Publications and source records attributed to D Taube.

At least 19 recordsLinked to original sources
PubMed2006

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.

Adult↗
PubMed2005

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 All patients were induced on prednisolone, tacrolimus, and MMF; steroids were withdrawn over 5 to 6 months.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.

Adult↗
PubMed2005

Steroid sparing in renal transplantation with tacrolimus and mycophenolate mofetil: three-year results.

Although renal transplantation with a 7-day steroid-sparing regimen, tacrolimus and mycophenolate, is associated with good short-term outcomes, late allograft dysfunction and failure remain concerns. In this study 101 consecutive patients underwent renal transplantation using this immunosuppressive regimen. In addition, anti-CD25 monoclonal antibody was used in 25 high-risk patients (regrafts, two-antigen human leukocyte antigen (HLA)-DR mismatch or sensitized with anti-HLA panel reactivity >30%). After a median follow-up of 39 months (range 29 to 49), overall patient survival is 98%, with two cardiac deaths. Three other graft losses occurred, one each to early venous thrombosis, polyoma viral nephropathy, and late rejection due to noncompliance. Therefore, overall graft survival is 95%. The acute rejection rate at 6 and 12 months was 19% (no rejection occurred between months 6 and 12). Late rejection was uncommon, with only two further episodes beyond 12 months. Mean creatinine at 12 months was 144 micromol/L and mean estimated glomerular filtration rate (GFR) of 55 mL/min. Graft function was stable at 3 years with a mean creatinine of 142 micromol/L and mean estimated GFR 56 mL/min. During the study, five patients developed posttransplant diabetes mellitus (two cases beyond 12 months). Tissue-invasive cytomegalovirus disease and BK viral nephropathy each occurred in three patients, with all episodes in the first 12 months. Mean weight gain is 3.3 kg and mean blood pressure is 135/81 on an average of 1.5 antihypertensive agents. This steroid-avoidance regimen is associated with excellent medium-term patient and graft outcomes and a low incidence of side effects.

Antibodies, Monoclonal↗
PubMed2005

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.

Adult↗
PubMed2005

Tacrolimus monitoring in renal transplantation: a comparison between high-performance liquid chromatography and immunoassay.

It is recommended that specific methods of tacrolimus monitoring rather than immunoassays, which overestimate tacrolimus levels, should be used in transplant recipients. Direct comparison of these techniques, however, has not been conducted in renal transplantation. In this study, 40 renal transplant recipients with tacrolimus monitoring by microparticle enzyme immunoassay (MEIA; target trough level 10 to 15 ng/mL) were compared with 40 patients monitored by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS; target trough level 8 to 13 ng/mL). All patients received anti CD25 antibody induction and mycophenolate mofetil in a steroid-sparing protocol. No differences were seen between MEIA and HPLC-MS groups in patient demographics. 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 3 and 6 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 four patients in the MEIA group and one patient in the HPLC-MS group (P < .2). No differences were seen for the following parameters at 3 or 6 months: biopsy-proven tacrolimus nephrotoxicity, serum creatinine or estimated creatinine clearance, systolic or diastolic blood pressure, cholesterol, cytomegalovirus disease, posttransplant diabetes, or tremor. This study suggests that renal transplantation with HPLC-MS monitoring of tacrolimus is safe and effective.

Blood Pressure↗
PubMed2003

Five-year results of kidney transplantation under tacrolimus-based regimes: the persisting significance of vascular rejection.

BACKGROUND: Acute rejection has been the major risk factor for medium-term kidney graft loss because of chronic allograft nephropathy. We investigated whether the use of improved immunosuppression has altered the relationship between acute and chronic rejection by analyzing data from 245 renal transplant patients receiving Tacrolimus-based immunosuppression. RESULTS: Five-year graft survival (censored for death with functioning graft) was 88.8% with no significant difference between living and cadaveric kidney transplants. The only significant predictor of medium-term graft loss was acute vascular rejection. CONCLUSION: Under Tacrolimus-based immunosuppression, the occurrence of acute interstitial rejection, even when occurring late, repeatedly, or with failure of graft function to return to baseline, was not associated with chronic allograft nephropathy or medium-term graft loss. Vascular rejection remains the major immunological obstacle to long-term transplant success. Five-year overall survival rates with a functioning graft of 80% with 90% graft survival censored for death with function seem to be realistic and achievable goals.

Adult↗
PubMed2001

Dose optimization of mycophenolate mofetil when administered with a low dose of tacrolimus in cadaveric renal transplant recipients.

BACKGROUND: Supplementation of immunosuppressive therapy with mycophenolate mofetil (MMF) has been found to reduce the rate of acute rejection in renal transplantation. We report a dose-finding study for MMF when administered in combination with low-dose tacrolimus and corticosteroid prophylaxis in cadaveric renal transplant recipients. METHODS: Two hundred thirty-two patients at 16 centers were enrolled in this randomized, parallel-group study. The three treatment groups were tacrolimus and corticosteroids (MMF-0 group, n=82); tacrolimus, corticosteroids, and 1 g of MMF daily (MMF-1 g group, n=79); and tacrolimus, corticosteroids, and 2 g of MMF daily (MMF-2 g group, n=71). Study duration was 6 months, and patients were followed up for patient and graft survival for 12 months. RESULTS: At 6 months posttransplantation, daily doses of 1 g and 2 g of MMF were associated with significantly lower rates of acute rejection compared with tacrolimus alone. The Kaplan-Meier rates were 48.5%, 24.9%, and 22.9%, respectively, for the three treatment groups when acute rejection was determined by clinical criteria (P=0.007). At month 12, patient survival rates were 100%, 97.5%, and 97.2% and graft survival rates were 90.2%, 92.4%, and 93.0% for the MMF-0 group, MMF-1 g group, and the MMF-2 g group, respectively. Gastrointestinal adverse events and leukopenia were higher in the MMF groups, especially in the MMF-2 g group (P<0.05). CONCLUSIONS: Low-dose tacrolimus combined with a MMF dose of 1 g daily and corticosteroids provided an optimized efficacy and safety profile. A higher dose of MMF (2 g) was associated with greater toxicity without a significant improvement in efficacy.

Adrenal Cortex Hormones↗
PubMed2001

Why is there so much end-stage renal failure of undetermined cause in UK Indo-Asians?

There is a high incidence of end-stage renal failure (ESRF) of undetermined cause in the Indo-Asian population of the UK. We studied patients presenting from the district of Brent and Harrow, which has a large Indo-Asian community, and whose renal services are largely provided by our centre. The diagnosis and ethnicity of patients starting renal replacement therapy and/or undergoing renal biopsy were collated. The incidences of ESRF, rates of renal biopsy and underlying diagnoses were calculated for Indo-Asians and Caucasians. Requirement for renal replacement therapy in Indo-Asians presenting to our centre from Brent and Harrow was 221/10(6)/year; no underlying diagnosis was identified in 77/10(6)/year. Renal biopsy rate in these patients was 456/10(6)/year, and the diagnostic categories significantly over-represented compared to Caucasians were: hypertension and ischaemia, focal segmental glomerulosclerosis (FSGS), idiopathic interstitial nephritis (IIN), diabetic nephropathy, minor glomerular abnormality, lupus nephritis and non-specific advanced chronic renal disease (p<0.001). The first three of these had a combined incidence of 135/10(6)/year in Indo-Asians and 31/10(6)/year in Caucasians. ESRF of undetermined cause is common in UK Indo-Asians, as is requirement for renal biopsy. Hypertension with ischaemia, FSGS and IIN are over-represented in the Indo-Asian population, and should be targeted for early diagnosis and treatment in this group.

Adult↗
PubMed2001

Haemodialysis and cerebral oedema.

BACKGROUND: Haemodialysis may cause neurological symptoms ranging from inconvenient feelings of disequilibrium to life-threatening neurological complications. There are animal data to suggest cerebral swelling may accompany haemodialysis and contribute symptomatically to dialysis disequilibrium. However, MR images acquired following haemodialysis often fail to demonstrate evidence of cerebral oedema. We wished to quantify any potential cerebral volume change which is caused by haemodialysis treatment. METHOD: Five renal patients and 5 control subjects had a two volumetric T1-weighted MRI scans on the same day. The patients were imaged immediately before and after haemodialysis. None were taking steroids. Precise positional matching (registration) was used to quantify cerebral volume change. RESULTS: Patients had an increase in cerebral volume following dialysis which averaged 32.8 ml (SE 7.4 ml, 3% brain volume). The change in the controls was 1.4 ml (SE 0.6 ml), p < 0.001. No patient had significant neurological symptoms. CONCLUSION: Cerebral oedema developed in the patients following dialysis. There is a good biological model for these observations. Modifications to dialysis may help. Common problems which increase cerebral volume, e.g. acute stroke, require careful appraisal in these patients. These observations need consideration when quantifying atrophy in dialysis patients.

Adult↗
PubMed2000

IgG2 anti-Galalpha1-3Gal does not induce porcine aortic endothelial cell accommodation in vitro.

BACKGROUND: Xenografts that have been protected from hyperacute rejection (HAR) are termed accommodated if they are not then rejected despite the presence of xenoantibody. It has been proposed that IgG may confer resistance to complement dependent cytotoxicity (CDC), a conventional in vitro marker of accommodation. We hypothesized that noncytotoxic IgG2 anti-Galalpha1-3Gal was responsible for this effect. METHODS AND RESULTS: We purified IgG anti-Galalpha1-3Gal from pooled human normal immunoglobulin and three sera, by elution from protein G and Galalpha1-3Gal-R immunoadsorbents. The eluates were IgM free and > or =95% IgG2. They bound to Galalpha1-3Gal, porcine aortic endothelial cells (PAEC) and lymphocytes. It was not possible to block IgM binding to PAEC or lymphocytes using IgG anti-Galalpha1-3Gal (200 microg/ml). The eluates were noncytotoxic in micro-CDC assays. To investigate accommodation, PAEC were cultured with subsaturating doses of the four IgG eluates for up to 144 hr. Resistance of nontrypsinized PAEC to CDC by human serum was measured in a cell viability assay. PAEC were not rendered resistant to CDC in any of the experiments. To investigate the possibility that accommodation might be induced by non-Galalpha1-3Gal IgG, the experiments were repeated using HNIg, again with no protection demonstrated. CONCLUSIONS: Using primary PAEC monolayers, we were unable to induce resistance to CDC with human normal immunoglobulin and its IgG2 anti-Gabeta1-3Gal subset. This contradicts previous experiments using trypsinized, immortalized cells. Although resistance to CDC is not an ideal marker of accommodation, the detrimental effects of IgG make it unlikely that it will become a useful clinical means of inducing accommodation.

Acute Disease↗
PubMed2000

Acute renal failure following cardiopulmonary bypass: a changing picture.

OBJECTIVE: To assess the incidence of acute renal failure (ARF) developing perioperatively in adult patients requiring cardiopulmonary bypass surgery (CPB) and to make comparisons with data from the same institution published earlier. DESIGN: Prospective, observational. SETTING: Tertiary referral centre for cardiopulmonary medicine. PATIENTS AND PARTICIPANTS: All patients admitted to the intensive care unit (ICU) who developed ARF perioperatively necessitating continuous veno-venous haemofiltration (CVVH) during the 24 months January 1997-December 1998. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Of 2337 adult patients undergoing cardiac surgery, 47 (2.0%) needed CVVH. Patients were excluded from analysis who underwent cardiac transplantation (n = 4), pericardial surgery (n = 3) or insertion of a left ventricular assist device (n = 1). Of the remaining 39, 21 patients died in ICU (53.8% mortality). Relatively more non-survivors suffered from diabetes, hypertension and preoperative renal dysfunction. A previous report from our Unit revealed that, in 1989-90, 2.7% of all patients undergoing CPB required CVVH with an in-hospital mortality of 83%. The current study population were older (65.3 vs 56.0 years in 1990), and more severely ill as evidenced by a higher percentage of patients requiring redo (30% vs 8.6% in 1990) and emergency (50% vs 25.7% in 1990) surgery. CONCLUSIONS: The need for CVVH following CPB may be diminishing despite increased risk factors. ARF-associated mortality in these circumstances is falling.

Acute Kidney Injury↗
PubMed1999

Chloramine-induced haemolysis presenting as erythropoietin resistance.

BACKGROUND: In December 1996 we identified an outbreak of erythropoietin (rHuEpo) resistance requiring a substantial increase in rHuEpo dosage in one of our four haemodialysis (HD) units. The dialysate chloramine levels in this unit had risen from <0.1 p.p.m. in 1996 to 0.25-0.3 p.p.m. in 1997. In the other three HD units levels remained <0.1 p.p.m. Other parameters of water quality were within accepted standards. METHODS: Monthly records of haemoglobin level and rHuEpo dose were available for 148 patients between January 1996 and May 1998. Seventy-two patients, with no recognized cause of rHuEpo resistance, were analysed in detail (August 1997 to April 1998). A subgroup of 15 patients was examined for evidence of haemolysis during HD (methaemoglobin and haptoglobin levels, reticulocyte counts and Heinz bodies). Larger carbon columns were installed in December 1997 to effect chloramine removal. RESULTS: There was an increase in mean methaemoglobinaemia of 23% (P<0.01) and a 21% fall in mean haptoglobin (P<0.01) across HD, although no patient had a reticulocytosis and only one patient with G6PD deficiency had Heinz bodies. Following installation of larger carbon columns there was an 18.6% rise (P<0.001) in mean haemoglobin level and a subsequent 25.0% reduction (P<0.001) in mean rHuEpo dose. Intradialytic changes in methaemoglobin and haptoglobin were abolished. The dialysate chloramine levels fell to < 0.1 p.p.m. Water company records subsequently revealed a sustained twofold increase in mains water chloramine from November 1996. CONCLUSIONS: This is the first report linking chloramine exposure and rHuEpo resistance, with only subtle signs of haemolysis. Unheralded changes in mains water constituents can directly affect dialysate water quality and clinical outcomes.

Adult↗
PubMed1998

Demonstration of IgM antibodies of high affinity within the anti-Galalpha1-3Gal antibody repertoire.

BACKGROUND: Human anti-Galalpha1-3Gal IgG and IgM xenoantibodies can distinguish between very similar epitopes with a high degree of selectivity. METHODS: Anti-Galalpha1-3Gal antibodies were affinity isolated using two separate Galalpha1-3Gal-based immunoadsorbents, Galalpha1-3Gal itself and Galalpha1-3Galbeta1-4Glc. IgG and IgM were separated using a protein G column. Antibody purity was achieved by serial adsorption/elutions from the columns. By this means, different antibody fractions were prepared that contained either IgG or IgM, reactive with either Galalpha1-3Gal, Galalpha1-3Galbeta1-4Glc, or both. The dissociation equilibrium constants (Kd) of these antibodies were then measured using an IAsys biosensor. RESULTS AND CONCLUSIONS: Sera from two individuals were used and Kd values for one IgG (fraction 1A) and two IgM (fractions 1B and 2A) fractions were obtained. The Kd for the IgG was 4.85 x 10(-7) M (fraction 1A). For IgM, the Kd values were higher at 7.8x10(-10) M (fraction 1B) and 1.07x10(-10) M (fraction 2A). Natural anti-pig antibodies include high affinity IgM that continue to be produced without class switch. The B cell mechanism behind this is not known. It may be possible to exploit this mechanism in future xenotransplantation strategies.

Antibodies↗
PubMed1998

Polymorphism in the human anti-pig natural antibody repertoire: implications for antigen-specific immunoadsorption.

BACKGROUND: Anti-Galalpha1-3Gal antibodies cause hyperacute rejection (HAR) in pig-to-primate xenotransplantation. Long-term graft survival has not been achieved despite abrogation of HAR using transgenic pigs. IgG and IgM anti-Galalpha1-3Gal also play a role in the events following abrogation of HAR. Characterizing these antibodies and developing a system for their removal is therefore crucial to future success in xenotransplantation. METHODS AND RESULTS: We have developed a neoglycoprotein enzyme-linked immunosorbent assay to probe the precise antigenic requirements for the binding of anti-Galalpha1-3Gal and have analyzed 77 normal sera. Sixty-six percent of individuals have IgG that recognizes the Galalpha1-3Gal di-, tri-, and pentasaccharides (D, T, and P, respectively), termed DTP phenotype. The frequency of other phenotypes was - -P, 13%; -TP, 12%; D-P, 8%; and DT-, 1%. The IgG subclasses found were IgG2 (95%), IgG3 (34%), IgG1 (31%), and IgG4 (17%). IgM in 91% of individuals recognized all three antigens. Further antibody heterogeneity was demonstrated when immunoadsorbents derived from Galalpha1-3Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc (PENTA) were tested. Galalpha1-3Galbeta1-4Glc (TRI 6) or PENTA agarose were effective for IgG removal in all individuals. For IgM removal, two deoxy derivatives were completely successful in 73% of individuals. Combining the Galalpha1-3Gal (DI) and TRI 6 agarose produced an adsorbent that completely removed anti-Galalpha1-3Gal IgG and IgM in all individuals tested. CONCLUSIONS: Although the polymorphism in the anti-Galalpha1-3Gal repertoire, which we have demonstrated, represents a major obstacle to the development of an effective immunoadsorbent, the combination of DI and TRI 6 agarose appears sufficient for pig-to-human xenotransplantation.

Animals↗