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Karsten Midtvedt

Publications and source records attributed to Karsten Midtvedt.

At least 19 recordsLinked to original sources
PubMed2006

Calcineurin inhibitor avoidance with daclizumab, mycophenolate mofetil, and prednisolone in DR-matched de novo kidney transplant recipients.

BACKGROUND: Calcineurin inhibitor (CNI)-free regimens posttransplantation have been claimed to conserve graft function in addition to reduce the risk factors for cardiovascular and malignant disease in renal transplant recipients. METHODS: The primary aim of this prospective, open-label, randomized, parallel-group, single-center study was to compare the effect of complete CNI-avoidance posttransplant (daclizumab + mycophenolate mofetil + prednisolone: Dac-group, n=27) with the standard CNI-based immunosuppressive protocol at our transplant unit (cyclosporine A + mycophenolate mofetil + prednisolone: CsA-group, n=27) on renal function (glomerular filtration rate [GFR] determined as plasma clearance of 51Cr-EDTA) in a selected low immunogenic risk population (DR-matched, PRA-negative de novo cadaveric transplant recipients). RESULTS: There were no significant difference in GFR at week 10 (P=0.61), but GFR was significantly (P=0.029) lower in the Dac-group (52+/-20 ml/min) at month 12 than in the CsA-group (69+/-29 ml/min). One-year patient and graft survival did not differ between the two groups. Overall acute rejection rate was 70.4% (19/27) in the Dac-group and 29.6% (8/27) in the CsA-group (P=0.006). CONCLUSIONS: The strategy to select DR-matched, PRA-negative de novo cadaveric transplant recipients for a CNI-avoidance protocol was not successful. The incidence of acute rejection was unacceptable high even though anti-CD25 antibody induction as well as initial higher mycophenolate mofetil doses (3 g/day) were applied, and renal function was significantly lower in the CNI-avoidance patients at 1 year. Other strategies need to be examined for avoidance of CNI's in the early posttransplant period.

Adult↗
PubMed2006

Genetic variability in BK Virus regulatory regions in urine and kidney biopsies from renal-transplant patients.

The human Polyomavirus BK (BKV) contains a hypervariable non-coding control region (NCCR), which regulates DNA replication and RNA transcription. The aim of this study was to characterize BKV NCCR-variants in kidney biopsies and urine samples from renal-transplant patients and to see whether there is any association between NCCR variability and BKV-nephropathy. Kidney biopsies and urine samples were examined from 11 patients with elevated serum creatinine and >5,000 genomic BKV copies per ml of urine. BKV-nephropathy was diagnosed in seven patients. Using PCR, BKV NCCR was amplified from urine from all BKV-nephropathy patients. The dominant NCCR corresponded to the archetype (WWT). In addition, a total of 14 non-archetype NCCR-variants were detected. Thirteen of these NCCR-variants were found in urine from one single BKV-nephropathy patient also suffering from hepatitis C. The NCCR of BKV was amplified from kidney biopsies of six BKV-nephropathy patients. Three patients demonstrated WWT NCCR, while three other patients harbored rearranged NCCR variants. The WWT NCCR was also detected in urine from control patients, except for one patient who harbored two non-archetypal NCCR variants. However, these variants were not resulting from complex rearrangements but instead had a linear NCCR anatomy with deletion(s) in the P-block. No BKV DNA was detected in biopsies from control patients. The results indicate that rearranged BKV NCCR is associated with BKV-nephropathy.

BK Virus↗
PubMed2006

Mycophenolic acid clinical pharmacokinetics influenced by a cyclosporine C2 based immunosuppressive regimen in renal allograft recipients.

Therapeutic drug monitoring of mycophenolic acid (MPA) in combination with cyclosporine 2-h concentration (CsA C2, n = 68) or tacrolimus trough concentration (n = 10) was investigated by repeated measurements of MPA and MPA-glucuronide (MPAG) trough concentrations in renal allograft recipients during the first 3 months post-transplant. The acute rejection rate was lower (19% vs. 43%; P < 0.05) in patients achieving CsA C2 target range during the first week (1600-2000 microg/l), n = 26, compared with those who did not, n = 42. Median MPA concentration was 0.9 and 1.2 microg/ml in patients within or below C2 range, respectively (P = 0.19). CsA C2 correlated with MPAG-to-MPA ratio (P < 0.01, r = 0.91) and gamma-glutamyl-transpeptidase (GGT, P < 0.01, r = 0.86). Total MPA concentration increased during the 3 months, but not in patients on tacrolimus. High CsA C2 lowered the acute rejection rate and plasma MPA. High CsA C2 is associated with elevated GGT, probably because of cholestatic effects, which explain the increased MPAG-to-MPA ratio. Increasing MPA concentration is ascribed to per-protocol CsA C2 reductions. In conclusion, CsA may confound the relationship between MPA and the incidence of rejection, and contribute to the difficulty of obtaining a therapeutic range for MPA in clinical practice.

Adrenal Cortex Hormones↗
PubMed2005

CD11c+ dendritic cells and plasmacytoid DCs are activated by human cytomegalovirus and retain efficient T cell-stimulatory capability upon infection.

It has been suggested that human cytomegalovirus (HCMV) evades the immune system by infecting and paralyzing antigen-presenting cells. This view is based mainly on studies of dendritic cells (DCs) obtained after culture of monocytes (moDCs). It is contradicted by the asymptomatic course of HCMV infection in healthy persons, indicating that other key antigen-presenting cells induce an efficient immune response. Here we show that HCMV activates CD11c+ DCs and plasmacytoid DCs (PDCs). In contrast to moDCs, CD11c+ DCs and PDCs produced interferon (IFN) type 1 when exposed to HCMV. Autocrine IFN type 1 partially protected CD11c+ DCs against infection, whereas PDCs were resistant to HCMV even when IFN type 1 activity was inhibited. HCMV exposure induced the maturation of CD11c+ DCs by IFN type 1-dependent and -independent mechanisms. Importantly, CD11c+ DCs infected by inhibiting IFN type 1 activity retained full capacity to stimulate T cells. Renal transplant recipients receiving immunosuppressive treatment had lower frequencies of CD11c+ DCs and PDCs in blood than did healthy controls. The results show that HCMV activates the immune system by interacting with CD11c+ DCs and PDCs and that recipients of renal transplants have low frequencies of these cell types in blood.

Antigen Presentation↗
PubMed2005

Evolution of the absorption profile of cyclosporine A in renal transplant recipients: a longitudinal study of the de novo and maintenance phases.

BACKGROUND: Therapeutic drug monitoring for cyclosporine microemulsion (CsA-ME) is often performed using either trough levels (C0) or levels at 2 h post-dose (C2). This analysis assessed changes in C0 and C2 and their relationship to CsA-ME dose over time post-transplant in renal transplant patients. METHODS: Data were obtained from MO2ART, a prospective multicentre trial in which CsA-ME dose was adjusted based on C2 level. All 98 patients in whom C0 and C2 were available at day 5, month 3 and month 12 were included, out of 234 who completed the 12 month study. Normalized dose (ND) of CsA-ME, defined as dose per kilogram body weight, was calculated, together with C0/ND, C2/ND and C2/C0. RESULTS: C0/ND and C2/ND both increased between day 5 and month 3: C0/ND from 33+/-15 to 53+/-24 (ng/ml)/(mg/kg) and C2/ND from 161+/-64 to 248+/-80 (ng/ml)/(mg/kg). Between month 3 and month 12, C2/ND remained stable but C0/ND decreased to 42+/-20 (ng/ml)/(mg/kg) while the C2/C0 ratio increased from 5.2+/-1.9 to 6.5+/-2.3, indicating an acceleration of drug elimination. The inter-individual coefficient of variation was higher for C0/ND than for C2/ND at 3 months (45 vs 32%, P<0.05) and at 12 months (48 vs 31%, P<0.01). CONCLUSIONS: CsA clearance accelerates between months 3 and 12 post-transplant, resulting in lower C0 levels for a given exposure (as measured by C2). As a consequence, C0 monitoring may progressively underestimate CsA exposure during the first year post-transplant. C2 monitoring contributes to improved individualized CsA-ME treatment in both the de novo phase and beyond month 3.

Aged↗
PubMed2005

Predictors of health-related quality of life in hypertensive recipients following renal transplantation.

BACKGROUND: Health-related quality of life (HRQoL) improves after renal transplantation. However, it is unclear which variables are the strongest determinants of HRQoL following renal transplantation. In this study, we wanted to assess whether antihypertensive medication, donor type, human leukocyte antigen (HLA)-compatibility or other variables could predict HRQoL 6-12 months after transplantation. METHODS: The study was a follow up of 124 patients recruited to a single center, randomized, double-blind clinical trial, comparing the effects of lisinopril and nifedipine in hypertensive renal transplant recipients. HRQoL was assessed with the Short Form 36 (SF-36) questionnaire. Bivariate and multiple linear regression analysis were used to assess the relationship between potential predictors and the physical component summary (PCS) and mental component summary (MCS) scales of the SF-36. RESULTS: Average scores 6-12 months after transplantation did not differ between patients randomized to lisinopril or nifedipine, or between cadaveric and living donor recipients on any of the eight SF-36 scales, or the two summary scales. In multivariate analyses, recipient age (p = 0.01) and cold ischemia time >14.5 h (p = 0.04) were independent predictors of the PCS score. Recipient age (p = 0.05), 2-4 HLA-AB mismatches (p = 0.05) and donor age (p = 0.03) were independent predictors of the MCS score. CONCLUSIONS: There was no evidence of differences in HRQoL according to lisinopril or nifedipine, or living vs. cadaveric donor transplantation. HRQoL was significantly reduced with longer cold ischemia time and more than one HLA-AB mismatches, after adjusting for age. These donor kidneys related issues need confirmation.

Adult↗
PubMed2005

Use of Neoral C monitoring: a European consensus.

Large-scale clinical trials using C(2) monitoring of cyclosporine (CsA) microemulsion (Neoral) in renal transplant recipients have demonstrated low acute rejection rates and good tolerability with a low adverse event profile in a variety of settings: with or without routine induction therapy; in combination with mycophenolate mofetil; with standard-exposure or low-exposure Neoral; and in patients with immediate or delayed graft function. In liver transplantation, C(2) monitoring significantly reduces the severity and incidence of acute rejection compared with C(0) monitoring, without adverse consequences in terms of renal function or tolerability. Different C(2) targets are appropriate depending on adjunctive immune suppression, level of immunologic risk, CsA tolerability, risk of renal toxicity and time since transplantation. CsA absorption may increase substantially in most patients during the first 1-2 weeks post-transplant, and this should be taken into account to avoid overshooting C(2) target range. A patient with a low C(2) value may be either a low or a delayed absorber of CsA, or be a normal absorber who is receiving too low a dose of Neoral. C(2) monitoring alone is insufficient to differentiate between these types of patients, and measurement of additional timepoints is recommended. Adopting C(2) monitoring in maintenance transplant patients identifies those who are overexposed to CsA. In summary, randomized, prospective, multicenter studies and single-center trials have evaluated Neoral C(2) monitoring within a range of regimens in different organ types, providing a robust evidence base for the benefits of this sensitive monitoring technique.

Absorption↗
PubMed2004

Insulin resistance after renal transplantation: the effect of steroid dose reduction and withdrawal.

Cardiovascular disease is a prevalent and serious complication after solid organ transplantation. Treatment with glucocorticoids is associated with increased risk for diabetes mellitus, insulin resistance, weight gain, hypercholesterolemia, and hypertension, all shown to be independent risk factors for cardiovascular disease. We sought to test the hypothesis that tapering of prednisolone (TAP) the first year after renal transplantation improves insulin sensitivity (IS), and to assess the effect of complete steroid withdrawal (SW) on IS in patients on a cyclosporine-based immunosuppressive regimen. All patients (n = 57) completed two consecutive hyperinsulinemic euglycemic glucose clamp procedures, a TAP group (n = 34) and a control group (n = 12) at 3 and 12 mo after transplantation, and a SW group (n = 11) before and 5 mo after SW. The IS index (ISI) was calculated as the glucose disposal rate divided by mean serum insulin the last 60 min of the clamp. In the TAP group, the mean (range) daily prednisolone was reduced from 16 (10 to 30) to 9 (5 to 12.5) mg accompanied by an average increased ISI of 24% (P = 0.008). In contrast, no significant change in ISI was observed in the control group (0%, P = 0.988). In the SW group, withdrawal of 5 mg prednisolone did not influence mean ISI significantly (-8%, P = 0.206). Lowering daily prednisolone toward 5 mg/d has beneficial effects on insulin action after renal transplantation, but withdrawal of 5 mg prednisolone may not influence IS significantly.

Body Weight↗
PubMed2003

C2 monitoring in maintenance renal transplant recipients: is it worthwhile?

Presently, there is little knowledge regarding cyclosporine (CsA) concentration at 2 hr post-dose (C2) monitoring in maintenance patients. This study evaluates the actual C2 range in stable renal transplant recipients (who underwent transplantation >12 months ago). In addition, we investigated whether underexposure or overexposure to CsA (assessed by C2) affects graft function (as measured by serum [S]-creatinine). All renal transplant recipients in Norway receiving CsA were asked to participate; 1447 fulfilled the criteria. Valid C2 and CsA trough concentration (C0) measurements were performed in 1032 renal transplant recipients (71%) monitored by C0. Target C0 level was 75 to 125 mumol/L. CsA levels were measured using a Cloned Enzyme Donor Immunoassay method, and all analyses were performed in the same laboratory (overall mean [+/-standard deviation] CsA C0=112+/-31 mug/L, CsA C2=697+/-211 mug/L [range 81-1580 mug/L], CsA dose [mg/day]=208+/-61, CsA dose [mg/kg/day]=2.8+/-1.1, and S-creatinine=141+/-58 mumol/L). A univariate analysis of variance showed that patients with C2 levels between 700 and 800 mug/L (n=203, S-creatinine=136+/-49 mumol/L) had significantly lower S-creatinine levels compared with patients with C2 levels greater than 950 mug/L (n=94, S-creatinine=152+/-56 mumol/L) (P<0.02). The same was true for patients with C2 levels less than 450 mug/L (n=95, S-creatinine 141+/-72 mumol/L) (P<0.05) when compared with patients with C2 levels greater than 950 mug/L. There was no significant difference in S-creatinine between patients in the low and intermediate C2 group; 666 patients had C0 levels in the therapeutic range (75-125 mumol/L). A linear regression showed a significant relation between S-creatinine and C2 for these patients (P=0.03). The corresponding relation between S-creatinine and C0 was nonsignificant (P=0.3). Monitoring of C2 in maintenance patients is a valuable tool to detect overexposure to CsA. Until results from prospective studies are available, we recommend C0 in the therapeutic range and reduction in CsA in overexposed patients, aiming at a C2 value between 700 and 800 mug/L.

Adult↗
PubMed2003

Individualized T cell monitored administration of ATG versus OKT3 in steroid-resistant kidney graft rejection.

Acute steroid-resistant rejection episodes are recommended to be treated with set doses of anti-thymocyte globulin (ATG) or anti-CD3 monoclonal antibody (OKT3). Individualized T cell monitoring has been proposed as a tool for dose finding. A randomized study comparing the efficacy and safety of ATG (n = 27) with OKT3 (n = 28) in the treatment of biopsy verified acute steroid-resistant rejection (ASRR) when both drugs were administered on the basis of daily individualized T cell measurements. A drop to below 50 cells/mm3 CD2+ T cells was considered adequate and used to guide the dose of ATG/OKT3. Demographic, clinical and histopathological severities of rejections were equal in the two groups. During the 10 days of T cell monitoring and antibody treatment, 13 patients were in need of dialysis (ATG = 7/OKT3 = 6). Two grafts did not respond to antibody treatment and were lost due to rejection (ATG = 1/OKT3 = 1). There were 26 biopsy verified re-rejections (ATG = 12/OKT3 = 14) within the first 3 months following antibody treatment. Mean serum creatinine (micromol/L) was similar in the two groups (ATG/OKT3: before rejection 157 +/- 72/151 +/- 88, at start of antibody treatment 308 +/- 125/330 +/- 94, end of antibody treatment 254 +/- 122/246 +/- 144 and at follow-up after a mean of 32 months 166 +/- 55 (n = 24)/164 +/- 57(n = 23)). To keep the T cell count below 50 cells/mm3, average dose ATG given was 354 +/- 151 mg (2.3 administrations, range 1-4) and average OKT3 was 32.5 +/- 6.8 mg in 10 doses. In conclusion, individualized T cell monitored administration of ATG and OKT3 is safe and seems as effective as a standard set dose in treatment of ASRR. Tailoring the dose for each individual patient lowers the cost.

Antilymphocyte Serum↗
PubMed2003

Pre-emptive therapy of CMVpp65 antigen positive renal transplant recipients with oral ganciclovir: a randomized, comparative study.

BACKGROUND: About one-quarter of renal transplant patients will suffer from symptomatic cytomegalovirus (CMV) disease if no preventive therapeutic measures are taken. In this prospective, randomized single-centre study pre-emptive therapy with oral ganciclovir is compared with conventional deferred treatment. METHODS: Renal transplant recipients (n= 455) over 18 years of age were screened weekly for CMV pp65 antigenaemia during the first 12 weeks post-transplantation. If CMV pp65 antigen in leukocytes appeared within 8 weeks post-transplantation patients were randomized and included in the study. Five patients developed CMV disease before positive CMV pp65, and 14 patients with a positive antigen test developed CMV disease before randomization could take place, all these representing a limitation of the applicability of the results in the overall renal transplant population. Altogether 179 patients were not randomized for various reasons. Eighty patients completed the study, 42 were randomized to receive pre-emptive oral ganciclovir therapy and 38 to conventional deferred treatment (control group). RESULTS: Time from transplantation to start of ganciclovir capsules was 36 (12-60) days and duration of oral ganciclovir therapy was 49 (27-70) days, median (range). No patient in the pre-emptive treatment group, but nine of 38 patients (23.7%) in the control group, developed CMV disease during the first 12 weeks post-transplantation (P= 0.0009). In the period from 3 months to 1 year post-transplantation, two patients in each group developed CMV disease. There were no significant differences in acute rejection or renal function between treatment groups during the first post-transplant year. CONCLUSIONS: Pre-emptive oral ganciclovir therapy in renal transplant recipients during the first 12 weeks post-transplantation effectively prevents CMV disease during this time period. The incidence of late CMV disease (3 months to 1 year after transplantation) was similar in the two groups, indicating that pre-emptive therapy does not result in late onset of CMV disease.

Administration, Oral↗
PubMed2003

Automated determination of free mycophenolic acid and its glucuronide in plasma from renal allograft recipients.

Mycophenolic acid, the active moiety of mycophenolate mofetil, inhibits the enzyme inosine monophosphate dehydrogenase. The main metabolite, mycophenolic acid glucuronide, has no immunosuppressive effect. Reported protein bindings are 97% for mycophenolic acid and 82% for mycophenolic acid glucuronide. Considerable intraindividual and interindividual variability in mycophenolic acid pharmacokinetics has been observed. Data on the variability of mycophenolic acid free fraction in plasma are sparse but may be relevant when discussing whether therapeutic drug monitoring of this drug is warranted. The authors describe a fully automated method for the determination of free concentrations by dialysis across a membrane followed by concentration of the dialysate on a trace enrichment column and liquid chromatography. Total concentrations are measured by protein precipitation and direct injection on the trace enrichment column. Plasma concentrations as low as 6 ng/mL free mycophenolic acid and 1 microg/mL free mycophenolic acid glucuronide can be measured with between-day coefficient of variation less than 15% and 6%, respectively. Stability testing confirmed that plasma samples could be stored for 14 days at 4 degrees C or -20 degrees C and at room temperature for approximately 12 hours without significant changes in free concentrations. Predose total and free concentrations of mycophenolic acid and mycophenolic acid glucuronide were determined in 27 samples from stable renal allograft recipients treated with mycophenolate mofetil, cyclosporin, and steroids. Total concentrations ranged from 0.57 to 16.2 microg/mL mycophenolic acid and 36 to 199 microg/mL mycophenolic acid glucuronide. Free concentrations ranged from 13 to 210 ng/mL mycophenolic acid and 8 to 58 microg/mL mycophenolic acid glucuronide. The method presented here has been successfully applied to measure free mycophenolic acid and free mycophenolic acid glucuronide in clinical samples. Further investigations may provide important data to support the identification of principles and target ranges for the monitoring of mycophenolic acid in the immunosuppressive therapy of organ transplant recipients.

Chromatography, High Pressure Liquid↗
PubMed2002

[Protein-creatinine ratio--a simple method for proteinuria assessment in clinical practice].

BACKGROUND: Proteinuria is an indicator of renal disease. Measurement of protein excretion is important for diagnosis and follow-up of renal disease, but measuring 24-hour protein excretion is a cumbersome procedure. MATERIAL AND METHODS: A simplified validated method for measuring excretion is obtained by measuring urine protein/creatinine concentration in a spot urine sample. RESULTS: We have implemented such ratios for clinical routine measurements of proteinuria at Rikshospitalet University Hospital in Oslo. Whenever protein or albumin in urine is requested, the laboratory also measures urine creatinine and reports the ratio in mg protein/mmol creatinine. 24-hour excretion is approximately 10 times the ratio. The rationale for using the ratio is given and proteinuria pathophysiology and potential risks and treatment options are discussed. INTERPRETATION: Our experience is that use of the urine protein/creatinine ratio is a significant improvement. Measurements are now routinely made whereas quantification was rarely performed when 24-hour urine samples were used. We recommend that physicians and laboratories implement the use of this ratio in their daily routines.

Albuminuria↗
PubMed2002

[Licorice--not just candy].

BACKGROUND: Liquorice is widely used as a flavour and also as a medical drug. Possible side effects include hypertension, hypokalaemia and metabolic alkalosis. MATERIALS AND METHODS: We present a case history and a review on liquorice intoxication based on relevant literature found from searches on Medline. RESULTS AND INTERPRETATION: A 19-year-old girl was admitted to hospital with severe hypertension, hypokalaemia and metabolic alkalosis. Urine analysis showed inhibition of 11-beta-hydroxysteroid dehydrogenase. It turned out that she ingested a lot of liquorice; after she stopped eating it she became normotensive without any medication. Three months later there were no signs of inhibition of the enzyme. The active component of liquorice is glycyrrhetinic acid, which inhibits the enzyme 11-beta-hydroxysteroid dehydrogenase. This enzyme promotes the conversion of cortisol to cortisone and is thereby responsible for the specificity of the mineralocorticoid receptor to aldosterone in the collecting tubules. Inhibition of the enzyme allows cortisol to act as the major endogenous mineralocorticoid producing a marked elevation in mineralocorticoid activity, resulting in hypertension, hypokalaemia and metabolic alkalosis.

Adult↗