Headache Prevalence Related to Haemoglobin and Ferritin. The HUNT Study

As clinic-based studies show an association between headache and both high and low levels of haemoglobin, we analysed this relationship in a population-based cross-sectional study (the HUNT Study). A total of 2385 women aged 20-55 years responded to a headache questionnaire and gave blood samples for measuring haemoglobin and ferritin. In the multivariate analyses, adjusting for age and education, there was a linear trend of decreasing prevalence of headache ( P = 0.02) and migraine ( P = 0.01) with decreasing haemoglobin. In particular, migraine was less likely among women with low haemoglobin (values < 11.5 g/dl) (odds ratio 0.4, confidence interval 0.2, 0.9). There was no correlation between headache prevalence and ferritin. The present findings may be relevant for the headache reported in polycythaemia and chronic altitude sickness.

Complexity of Host Micro-RNA Response to Cytomegalovirus Reactivation After Organ Transplantation

Human (Homo sapiens) micro-RNAs (hsa-miRNAs) regulate virus and host-gene translation, but the biological impact in patients with human cytomegalovirus (hCMV) infection is not well defined in a clinically relevant model. First, we compared hsa-miRNA expression profiles in peripheral blood mononuclear cells from 35 transplant recipients with and without CMV viremia by using a microarray chip covering 847 hsa-miRNAs. This approach demonstrated a set of 142 differentially expressed hsa-miRNAs. Next, we examined the effect of each of these miRNAs on viral growth by using human fibroblasts (human foreskin fibroblast-1) infected with the hCMV Towne strain, identifying a subset of proviral and antiviral hsa-miRNAs. miRNA-target prediction software indicated potential binding sites within the hCMV genome (e.g., hCMV-UL52 and -UL100 [UL = unique long]) and host-genes (e.g., interleukin-1 receptor, IRF1). Luciferase-expressing plasmid constructs and immunoblotting confirmed several predicted miRNA targets. Finally, we determined the expression of selected proviral and antiviral hsa-miRNAs in 242 transplant recipients with hCMV-viremia. We measured hsa-miRNAs before and after antiviral therapy and correlated hsa-miRNA expression levels to hCMV-replication dynamics. One of six antiviral hsa-miRNAs showed a significant increase during treatment, concurrent with viral decline. In contrast, six of eight proviral hsa-miRNAs showed a decrease during viral decline. Our results indicate that a complex and multitargeted hsa-miRNA response occurs during CMV replication in immunosuppressed patients. This study provides mechanistic insight and potential novel biomarkers for CMV replication.

Evaluation of an In Silico PBPK Post-Bariatric Surgery Model through Simulating Oral Drug Bioavailability of Atorvastatin and Cyclosporine

An increasing prevalence of morbid obesity has led to dramatic increases in the number of bariatric surgeries performed. Altered gastrointestinal physiology following surgery can be associated with modified oral drug bioavailability (Foral). In the absence of clinical data, an indication of changes to Foral via systems pharmacology models would be of value in adjusting dose levels after surgery. A previously developed virtual "post-bariatric surgery" population was evaluated through mimicking clinical investigations on cyclosporine and atorvastatin after bariatric surgery. Cyclosporine simulations displayed a reduced fraction absorbed through gut wall (fa) and Foral after surgery, consistent with reported observations. Simulated atorvastatin Foral postsurgery was broadly reflective of observed data with indications of counteracting interplay between reduced fa and an increased fraction escaping gut wall metabolism (FG). Inability to fully recover observed atorvastatin exposure after biliopancreatic diversion with duodenal switch highlights the current gap regarding the knowledge of associated biological changes.CPT: Pharmacometrics & Systems Pharmacology (2013) 2, e47; doi:10.1038/psp.2013.23; advance online publication 12 June 2013.

Effects of the intensity of immunosuppressive therapy on outcome of treatment for CMV disease in organ transplant recipients

An effective host immune response, critical for successful control of Cytomegalovirus (CMV) disease in solid organ transplant recipients, is affected by intensity and type of immunosuppressive therapy. We used information prospectively captured in the VICTOR-trial to investigate the impact of immunosuppressive therapy on short- and long-term outcomes of CMV treatment in organ transplant recipients. Dual, as compared to triple, immunosuppressive therapy ([odds ratios] OR of 2.55; 95% CI: 1.51-4.60; p = 0.002), lower blood concentrations of calcineurin inhibitors (OR of 5.53; CI: 1.04-29.35; p = 0.045), and longer time since transplantation (OR of 1.70; CI: 1.01-2.87; p = 0.047) all showed better early (Day 21) CMV DNAemia eradication. We observed no effect of the intensity of the immunosuppressive therapy on overall rates of viral eradication or recurrence. The type of calcineurin inhibitor (tacrolimus/cyclosporine) or use of mycophenolate did not affect treatment efficacy, although both tacrolimus and mycophenolate treated patients showed a lower rate of virological recurrence OR 0.51 (95% CI: 0.26-0.98; p = 0.044) and OR 0.45 (95% CI: 0.22-0.93; p = 0.031), respectively. Lower total intensity of immunosuppressive therapy was associated with more effective early, but not overall, CMV DNAemia eradication by valganciclovir/ganciclovir therapy. Both mycophenolate and tacrolimus (rather than cyclosporine) therapy seem to be associated with reduced risk of recurrence.

Intra- and Interhospital Repeatability of Radionuclide Left Ventricular Ejection Fraction in Post-Infarction Patients

OBJECTIVE

To evaluate intra- and interobserver and interhospital repeatability of radionuclide left ventricular ejection fraction in post-infarction patients.

DESIGN

The study comprised 131 patients who were examined in three different hospitals 2-7 days post infarction. The radionuclide examinations were conducted in a standardized manner, and different observers carried out repeated measurements blind on the stored raw data.

RESULTS

The coefficients of variation were between 1.5% and 6.2%, and limits of agreement between +/- 0.012 and 0.056. There were no significant differences between the intra- and interobserver or interhospital repeatability in average, but some significant differences between individual observers were noted.

CONCLUSION

The repeatability of LVEF was acceptable, with limits of agreement in the range +/- 0.012-0.056. Some differences between observers and hence hospitals were noted, which may be of clinical relevance.

Analytical quality goals derived from the total deviation from patients' homeostatic set points, with a margin for analytical errors

The deviation of test results from patients' homeostatic set points in steady-state conditions may complicate interpretation of the results and the comparison of results with clinical decision limits. In this study the total deviation from the homeostatic set point is defined as the maximum absolute deviation for 95% of measurements, and we present analytical quality requirements that prevent analytical error from increasing this deviation to more than about 12% above the value caused by biology alone. These quality requirements are: 1) The stable systematic error should be approximately 0, and 2) a systematic error that will be detected by the control program with 90% probability, should not be larger than half the value of the combined analytical and intra-individual standard deviation. As a result, when the most common control rules are used, the analytical standard deviation may be up to 0.15 times the intra-individual standard deviation. Analytical improvements beyond these requirements have little impact on the interpretability of measurement results.

Significantly altered systemic exposure to atorvastatin acid following gastric bypass surgery in morbidly obese patients

The impact of gastric bypass on atorvastatin pharmacokinetics was investigated in 12 morbidly obese patients being treated with 20-80 mg atorvastatin each morning. Eight-hour pharmacokinetic investigations were performed the day before the surgery and at a median of 5 weeks (range 3-6 weeks) after the surgery. Gastric bypass surgery produced a variable effect on individual systemic exposure to atorvastatin acid (area under the plasma concentration vs. time curve from 0 to 8 h postdose (AUC(0-8))), ranging from a threefold decrease to a twofold increase (median ratio = 1.1, P = 0.99). Patients with the highest systemic exposure to atorvastatin before surgery showed reduced exposure after surgery (n = 3, median ratio = 0.4, range = 0.3-0.5, P < 0.01), whereas those with lower systemic exposure before surgery showed a median 1.2-fold increase in atorvastatin AUC(0-8) (n = 9, range = 0.8-2.3, P = 0.03) after surgery. This study indicates that the presurgical first-pass metabolic capacity influences the effect of gastric bypass on atorvastatin bioavailability. Because individual first-pass metabolic capacity is not readily assessable clinically, retitration up to the lowest effective dose should be performed after the surgery.

Long-term outcomes of CMV disease treatment with valganciclovir versus IV ganciclovir in solid organ transplant recipients

Though an important cause of morbidity and mortality in solid organ transplantation (SOT), the long-term outcomes of cytomegalovirus (CMV) disease treatment have not been well studied. In a randomized trial, 321 SOT recipients with CMV disease were followed 1 year after treatment with either twice daily intravenous ganciclovir or oral valganciclovir (for 21 days) followed by once daily valganciclovir until day 49 in all patients. Clinical and viral eradication of CMV disease was similar between groups. Clinical recurrence beyond day 49 was found in 15.1% and virological recurrence in 30.0%, no difference between groups (p > 0.77). In a multivariable logistic regression analysis, the only independent predictor for recurrence was failure to eradicate DNAemia by day 21 (clinical: OR 3.9 [1.3-11.3], p = 0.012; virological: OR 5.6 [2.5-12.6], p < 0.0001). Eight patients developed ganciclovir resistance, with no difference between groups (p = 0.62). Twenty patients (valganciclovir: 11, ganciclovir: 9, p = 0.82) died, 12 due to infections, two involving CMV disease. There were no differences in long-term outcomes between treatment arms, further supporting the use of oral valganciclovir for treatment of CMV disease. Persistent DNAemia at day 21, CMV IgG serostatus and development of resistance may be relevant factors for further individualization of treatment.

An assessment of herpesvirus co-infections in patients with CMV disease: correlation with clinical and virologic outcomes

The effect of herpesvirus co-infections (HHV-6, HHV-7) on cytomegalovirus (CMV) disease and its response to therapy is unknown. We prospectively analyzed herpesvirus co-infections in transplant recipients with CMV disease. All patients received 3 weeks of antiviral therapy. Samples were collected at baseline (day 0) and then day 3, 7, 14 and 21 poststart of therapy. Viral load testing for CMV, HHV-6 and HHV-7 was done using quantitative PCR assays in 302 patients of whom 256 had documented symptomatic CMV viremia. In this subset, day 0 HHV-6 co-infection was present in 23/253 (9.1%) and HHV-7 in 17/253 (6.7%). Including those positive at any time point raised the prevalence to 79/256 (30.9%) for HHV-6 and 75/256 (29.3%) for HHV-7. Viral co-infection did not influence the response of CMV disease to antiviral therapy. Baseline CMV viral loads, time to eradication and risk of recurrence were similar in patients with and without HHV-6 or HHV-7 co-infection. Ganciclovir and valganciclovir had no clear effect on HHV-6 and HHV-7 viremia. In conclusion, herpesvirus co-infections are common in patients with CMV disease but with standard antiviral therapy, no clear clinical effects are discernable. Routine monitoring for viral co-infection in patients with CMV disease is not indicated.

Health-associated reference values for arginine, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) measured with high-performance liquid chromatography

OBJECTIVE

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide production. It has been implicated in various pathological processes, especially processes involving the cardiovascular system. Plasma concentration of ADMA (p-ADMA) has been measured in several studies with different techniques, and a wide range of normal values has been published. With use of high performance liquid chromatography (HPLC) with fluorescence detection, we have established health-associated reference values for p-ADMA, p-arginine, p-SDMA and the p-arginine/p-ADMA and p-arginine/p-SDMA ratios.

MATERIAL AND METHODS

Blood samples were taken from 238 blood donors (112 F and 126 M). HPLC was used to analyse arginine, ADMA and SDMA. Reference values are presented as 2.5 and 97.5 percentiles estimated by the bootstrap method.

RESULTS

The reference interval for p-ADMA is 0.40-0.77 micromol/L for the whole population, 0.41-0.79 micromol/L for men, 0.38-0.73 micromol/L for women 45 years or less, and 0.41-0.84 micromol/L for women >45 years.

CONCLUSIONS

Age affects p-ADMA in healthy women, but not in men.

Oral valganciclovir is noninferior to intravenous ganciclovir for the treatment of cytomegalovirus disease in solid organ transplant recipients

Intravenous ganciclovir is the standard treatment for cytomegalovirus disease in solid organ transplant recipients. Oral valganciclovir is a more convenient alternative. In a randomized, international trial, recipients with cytomegalovirus disease were treated with either 900 mg oral valganciclovir or 5 mg/kg i.v. ganciclovir twice daily for 21 days, followed by 900 mg daily valganciclovir for 28 days. A total of 321 patients were evaluated (valganciclovir [n = 164]; i.v. ganciclovir [n = 157]). The success rate of viremia eradication at Day 21 was 45.1% for valganciclovir and 48.4% for ganciclovir (95% CI -14.0% to +8.0%), and at Day 49; 67.1% and 70.1%, respectively (p = NS). Treatment success, as assessed by investigators, was 77.4% versus 80.3% at Day 21 and 85.4% versus 84.1% at Day 49 (p = NS). Baseline viral loads were not different between groups and decreased exponentially with similar half-lives and median time to eradication (21 vs. 19 days, p = 0.076). Side-effects and discontinuations of assigned treatment (18 of 321 patients) were comparable. Oral valganciclovir shows comparable safety and is not inferior to i.v. ganciclovir for treatment of cytomegalovirus disease in organ transplant recipients and provides a simpler treatment strategy, but care should be taken in extrapolating to organ transplant recipients not properly represented in the present study.

Evaluation of the pharmacokinetic interaction between fluvastatin XL and cyclosporine in renal transplant recipients

OBJECTIVE

To assess the pharmacokinetic interaction between cyclosporine and extended-release fluvastatin (fluvastatin XL), 80 mg for 7 days, in stable renal transplant recipients.

METHODS

This was a single-center, open-label study. 17 renal transplant recipients received their standard cyclosporine therapy (Days 1 - 9) plus a once-daily single oral dose of fluvastatin XL, 80 mg (Days 2 - 8). Blood samples were collected and cyclosporine (whole blood) and fluvastatin (plasma) concentrations determined by radioimmunoassay and HPLC fluorescence detection, respectively. Pharmacokinetic parameters were calculated using non-compartment analysis and fluvastatin results were compared with historical controls.

RESULTS

Treatment with fluvastatin XL, 80 mg for 7 days, had no significant effect on either the AUC0-12 (3,644 ng x h/ml in the absence of fluvastatin vs. 3,534 ng x h/ml in the presence of fluvastatin) or the Cmax of cyclosporine (983 ng/ml in the absence of fluvastatin vs. 945 ng/ml in the presence of fluvastatin). Co-administration of fluvastatin XL also had no effect on the tmax, t1/2 or apparent clearance (CL/F) of cyclosporine in renal transplant patients. The AUC and Cmax for fluvastatin XL in the presence of cyclosporine (AUC0-24 1,192 ng. x h/ml, Cmax 271 ng/ml) were approximately 2-fold higher compared with historical data for fluvastatin XL alone in healthy volunteers (AUC0-24 630 ng x h/ml, Cmax 102 ng/ml) but lower than the historical data for fluvastatin IR, 40 mg b.i.d. alone in healthy volunteers (AUC0-24 1,340 ng x h/ml, Cmax 443 ng/ml). Tmax, t1/2 and trough levels of fluvastatin in the presence of cyclosporine were also similar to the historical controls. Concomitant administration of cyclosporine and fluvastatin XL was well tolerated by renal transplant recipients.

CONCLUSIONS

Fluvastatin XL, 80 mg, and cyclosporine do not show clinically relevant pharmacokinetic interactions.

Combined therapy with atorvastatin and calcineurin inhibitors: no interactions with tacrolimus

Increased systemic exposure to statins and consequent risk for complications has been reported in patients concomitantly treated with cyclosporin A (CsA). This has been ascribed to inhibition of drug catabolism by cytochrome P450 3A4 (CYP3A4) or drug transport by P-glycoprotein (PGP) and organic anion transporting polypeptide (OATP1B1). It is not known whether the combination of statins and tacrolimus (Tac) also suffers from this drawback. Therefore, a pharmacokinetic study of atorvastatin and its metabolites was performed in 13 healthy volunteers after 4 days' treatment, and after short (12 h) concomitant exposure to CsA and Tac. A complementary assessment of overall CYP, and hepatic and intestinal CYP3A4+PGP activity was performed after each treatment episode and compared to baseline (no drugs). Systemic exposure to atorvastatin acid and its metabolites was significantly increased when administered with CsA. In contrast, intake of Tac did not have any impact on atorvastatin pharmacokinetics. Concomitantly, a profound decrease of hepatic and intestinal PGP and an increase of intestinal CYP3A4 were noted with CsA, whereas no effect was seen after atorvastatin therapy with or without Tac. Based on these findings treatment with Tac appears a safer option for patients needing a combination of statins and calcineurin inhibitors.

Effects of autotransfusion of mediastinal shed blood on biochemical markers of myocardial damage in coronary surgery

BACKGROUND

Previous studies have shown conflicting results regarding the effect of autotransfusion of mediastinal shed blood after coronary artery bypass grafting (CABG) on the serum levels of myocardial band (MB) isoenzymes of creatine kinase (CK-MB) and cardiac troponins. The effect of autotransfusion on serum levels of human heart fatty acid binding protein (H-FABP), another marker of myocardial necrosis, has not been studied. The aim of the present study was to investigate the effects of autotransfusion of mediastinal shed blood on the serum levels of CK-MB, cardiac troponin T (cTnT), and H-FABP after uncomplicated primary CABG.

METHODS

Fifty patients were randomized to post-operative autotransfusion of mediastinal shed blood or no autotransfusion. Blood samples for the analysis of the biochemical markers of myocardial damage were drawn pre-operatively and 1, 4, 12, 24, 48, and 72 h after the termination of cardiopulmonary bypass. Samples from the mediastinal shed blood were collected after 1 and 4 h.

RESULTS

The levels of the biochemical markers of myocardial injury were all markedly elevated in mediastinal shed blood. Autotransfusion did not significantly affect the serum levels of cTnT or H-FABP. However, during the early post-operative hours, there was a trend towards a higher level of cTnT and H-FABP in the autotransfusion group. During the first 24 h after surgery, the autotransfusion group had a significantly higher serum level of CK-MB.

CONCLUSION

Post-operative autotransfusion of mediastinal shed blood may contribute to elevated serum levels of biochemical markers of myocardial injury.

Combined therapy with atorvastatin and calcineurin inhibitors: no interactions with tacrolimus

Increased systemic exposure to statins and consequent risk for complications has been reported in patients concomitantly treated with cyclosporin A (CsA). This has been ascribed to inhibition of drug catabolism by cytochrome P450 3A4 (CYP3A4) or drug transport by P-glycoprotein (PGP) and organic anion transporting polypeptide (OATP1B1). It is not known whether the combination of statins and tacrolimus (Tac) also suffers from this drawback. Therefore, a pharmacokinetic study of atorvastatin and its metabolites was performed in 13 healthy volunteers after 4 days' treatment, and after short (12 h) concomitant exposure to CsA and Tac. A complementary assessment of overall CYP, and hepatic and intestinal CYP3A4+PGP activity was performed after each treatment episode and compared to baseline (no drugs). Systemic exposure to atorvastatin acid and its metabolites was significantly increased when administered with CsA. In contrast, intake of Tac did not have any impact on atorvastatin pharmacokinetics. Concomitantly, a profound decrease of hepatic and intestinal PGP and an increase of intestinal CYP3A4 were noted with CsA, whereas no effect was seen after atorvastatin therapy with or without Tac. Based on these findings treatment with Tac appears a safer option for patients needing a combination of statins and calcineurin inhibitors.

Iron status among 3005 women aged 20-55 years in Central Norway: the Nord-Trøndelag Health Study (the HUNT study)

OBJECTIVE

To describe the iron status of Norwegian women of fertile age, to show the prevalence of iron-deficiency anemia and iron overload, and to demonstrate possible factors connected to and/or influencing iron status.

MATERIAL AND METHODS

The diagnostic criteria were: (a) anemia: hemoglobin (Hb) < 120, < 117, or < 115 g/l; (b) depleted iron stores: serum ferritin (SF) < 10 or 12 microg/l; iron-deficiency anemia: (a)+(b). Iron overload: SF > or = 110 microg/l. The study was conducted in Central Norway where a total of 3005 women aged 20 to 55 years were enrolled in a health survey program (the HUNT Study). None of the women were pregnant and none had been blood donors in the two previous years.

RESULTS

Median SF was 31.0 microg/l. Depleted iron stores were present in 10.9 and 15.1%, respectively. The Hb 2.5%tile among the iron-replete women was 117 g/l. With this cut-off value, anemia was present in 4.7% and iron-deficiency anemia in about 3%. Iron overload was present among 5.2%, and homozygous primary hemochromatosis among 0.4%.

CONCLUSIONS

The prevalence of iron-deficiency anemia was relatively low and similar to that found earlier in small groups of Norwegian women. The prevalence is comparable with results from other developed countries.

Reference intervals for procalcitonin and C-reactive protein after major abdominal surgery

Procalcitonin (PCT). a new marker proposed as a diagnostic tool for bacterial infections, triggers a systemic-inflammatory reaction in the body (sepsis, septic shock) and has potential use in a wide range of patient settings. To interpret the results from PCT measurements, we depend on reference intervals established from relevant populations. PCT and C-reactive protein (CRP) concentrations were analysed in 47 patients with a normal postoperative course after major abdominal surgery. The mean concentration of PCT declines from the first day and reaches half its initial values on the second day after the operation. whereas the mean concentration of CRP increases in the first 48 h and reaches half its maximum value on the fifth day after the operation. We present a continuous reference interval for plasma PCT and CRP concentrations in the first week following major abdominal surgery. For PCT we also present a graphic display of expected mean and expected upper reference limits predicted from the value measured on the first postoperative day.

Benefit of population-based screening for phenotypic hemochromatosis in young men

BACKGROUND

Hereditary hemochromatosis (HH) is a common genetic disease leading to accumulation of iron in the body, most notably in the liver. More men than women become clinically ill. The prognosis is excellent if phlebotomy treatment is started before liver cirrhosis develops. Screening has been recommended, but the benefit of population-based screening has never been shown in a randomized clinical trial. In this article, we estimate the benefit of screening young men, using a theoretical model.

METHODS

A phenotypic screening scenario was modelled using a decision tree. Gain of quality-adjusted life-years was used as a measure of benefit, and estimated using Markov processes. Data on the accuracy of the screening tests, the prevalence of HH and the risk of liver cirrhosis were mainly derived from a cross-sectional study on the prevalence and morbidity of HH in 30509 men. Data on the excess mortality of cirrhosis were taken from relevant literature. Sensitivity analysis was done for important variables.

RESULTS

Assuming basal case values for variables, screening a cohort of 1000 men aged 30 years for phenotypic HH would gain about 8 quality-adjusted life-years, compared to awaiting symptomatic disease. Based on actual costs of our cross-sectional study, the screening cost was US$250 per quality-adjusted life-year gained. The prevalence of phenotypic HH, the excess mortality of liver cirrhosis, the quality of life in non-cirrhotic HH patients, and the fractions of patients compliant with treatment were the most important variables in the sensitivity analysis.

CONCLUSION

Incorporating screening for phenotypic HH in health survey programmes for young men may be worthwhile.

Intake of grapefruit juice alters the metabolic pattern of cyclosporin A in renal transplant recipients

OBJECTIVE

The aim of the present study was to investigate the effect of grapefruit juice on the pharmacokinetics of cyclosporin A (CsA), as Sandimmun Neoral, and its main metabolites, M1, M9 and M4N, in renal transplant recipients.

METHODS

Ten renal transplant recipients, on CsA-based immunosuppressive therapy, were included in this open, randomized crossover study. Patients were given their individualized morning dose of CsA, administered with either 250 ml water or 250 ml grapefruit juice and 12-hour CsA pharmacokinetic investigations were performed. The 2 investigation days were separated by at least 7 days.

RESULTS

Administration of CsA with grapefruit juice compared with water significantly increased the area under the whole blood concentration versus time curve in the interval from 0-12 hours (AUC(0-12)) of CsA, by an average of 25 +/- 19% (p = 0.002). Intake of grapefruit juice did not have any significant influence on maximum whole blood concentration (Cmax) or time to Cmax (tmax) of CsA. AUC(0-12) and Cmax of M9 decreased significantly with intake of grapefruit juice, on average 22 +/- 11% (p = 0.0007) and 36 +/- 6% (p = 0.0001), respectively. AUC(0-12) of M1, however, was on average 13 +/- 14% (p = 0.02) higher upon co-administration of CsA with grapefruit juice as compared with water. The level of M4N was below the limit of quantification in most samples, and an effect of co-administration of CsA with grapefruit juice could not be determined for this metabolite.

CONCLUSION

The present study shows that co-administration of grapefruit juice with CsA compared with water affects the formation and/or elimination of the 2 metabolites M1 and M9 differently. In addition, administration of CsA with grapefruit juice compared with water induced a moderate, but significant increase in systemic exposure of CsA in renal transplant recipients.

Persons with screening-detected haemochromatosis: as healthy as the general population?

BACKGROUND

Hereditary haemochromatosis (HH) is a common genetic disease leading to iron deposition in the liver and other organs. Early treatment will prevent clinical disease and population-based screening for HH has been advocated. However, the benefit of screening depends on the morbidity of HH. We have compared the morbidity in HH persons detected by screening with the morbidity in the rest of the population.

METHODS

All inhabitants 20 years or older in a Norwegian county (94,191 persons) were invited to participate in a health survey programme. Of 65,717 participating persons, a blood specimen for transferrin saturation was obtained from 65,238. After repeated laboratory testing and clinical examination, 269 persons were found to have phenotypic HH, while 297 had genotypic HH (the C282/C282Y mutation). Using self-reported data, clinical examinations and analysis of non-fasting blood samples, the morbidity in phenotypic and genotypic HH persons was compared with the morbidity in the rest of the population. All data were collected before subjects were diagnosed with HH, and all comparisons were corrected for age and gender.

RESULTS

Compared to control persons, phenotypic and genotypic HH men and women had a higher score on 1 of 17 questions dealing with joint complaints. Phenotypic and genotypic HH women below 50 years of age had a higher prevalence of hypothyroidism (15.2% and 12.5%, respectively, compared to 3.0% in the control population). Phenotypic HH women below 50 years of age had higher diastolic blood pressure than control women. Phenotypic HH men above 50 years of age and genotypic HH men scored lower than control men on a compound myocardial infarction risk score variable, in part due to lower serum cholesterol concentration. Fewer phenotypic HH men above 50 years of age reported having angina pectoris. Otherwise, the health of phenotypic and genotypic HH persons was not different from the health of control persons.

CONCLUSION

When corrected for age and gender, the morbidity in persons with screening-detected HH was not very different from the morbidity in the control group, indicating that population-based screening may not be as beneficial as anticipated.

Bilateral pharmacokinetic interaction between cyclosporine A and atorvastatin in renal transplant recipients

Atorvastatin is increasingly used as a cholesterol-lowering agent in solid organ transplant recipients receiving cyclosporine A (CsA). However, the potential bilateral pharmacokinetic interaction between atorvastatin and CsA in renal transplant recipients has not previously been examined. Baseline 12-h CsA pharmacokinetic investigation was performed in 21 renal transplant recipients and repeated after 4 weeks of atorvastatin treatment (10 mg/ d). At week 4, 24-h pharmacokinetics of atorvastatin was also performed. All patients received basiliximab induction followed by CsA and prednisolone immunosuppression. Compared with historic controls, CsA-treated patients showed, on average, sixfold higher plasma HMG-CoA reductase inhibitory activity after 4 weeks of atorvastatin treatment (p < 0.05). Atorvastatin had a moderate effect on the pharmacokinetics of CsA and reduced the AUC0-12 (area under curve, 0-12h) by 9.5 +/- 18% (p = 0.013) and Cmax (maximal concentration) by 13.5 +/- 24% (p =0.009), while C12 (trough level) was unchanged (p =0.42). Total and LDL cholesterol decreased by 26.8 +/- 8.4% (p < 0.0001) and 41.5 +/- 11.0% (p < 0.0001), respectively. Bilateral pharmacokinetic interaction between atorvastatin and CsA resulted in sixfold higher plasma HMG-CoA reductase inhibitory activity, but only a moderate decrease in systemic exposure of CsA.

Screening for hemochromatosis: high prevalence and low morbidity in an unselected population of 65,238 persons

BACKGROUND

Hereditary hemochromatosis (HH) is a common genetic disease leading to accumulation of iron in several organs, most notably the liver. The C282Y/C282Y mutation in the HFE gene is found in most cases. In order to prevent clinical disease and to study the cost and feasibility of screening, a large population was screened.

METHODS

In a Norwegian county, all inhabitants 20 years or older were invited to participate in a population-based health survey programme. Screening for HH was one of several subprojects. Blood samples were obtained from 65,238 persons. Subjects with high serum transferrin saturation in two tests and high serum ferritin were clinically evaluated for HH. All subjects with high serum transferrin saturation in two tests were offered genotyping.

RESULTS

HH was newly diagnosed in 92 women and 177 men. Phlebotomy treatment was performed in 64 women and 152 men. Severe organ damage (liver cirrhosis) was ascertained in only 4 men. We found no correlation between serum ferritin and age. The estimated cost was US$ 1.6 per subject screened and US$ 390 per newly discovered HH subject. The estimated prevalence of phenotypical HH not previously known was 0.34% in women and 0.68% in men. The prevalence of the C282Y/C282Y mutation was at least 0.68%.

CONCLUSION

Large-scale screening for HH can be performed at a relatively low cost if combined with a health survey programme. The yield in terms of newly discovered cases is considerable, but few cases were found seriously ill. Better knowledge of the natural course of HH is necessary if we are to be able to estimate the cost-effectiveness of large-scale screening.

Atorvastatin improves endothelial function in renal-transplant recipients

BACKGROUND

Hyperlipidaemia and endothelial dysfunction are common features in cyclosporin A (CsA)-treated renal transplant recipients. Endothelial dysfunction may contribute to the risk of premature atherosclerosis and cardiovascular death in these patients. A beneficial effect of statin therapy beyond cholesterol lowering may be an improvement of endothelial function. The present study was designed to assess the effect of atorvastatin on serum lipids and endothelial function in CsA treated renal transplant recipients.

METHODS

This pilot study was an open trial of 4 weeks atorvastatin (10 mg per day) treatment in renal transplant recipients (n=22). All patients received a CsA- and prednisolone-based immunosuppressive regimen. Endothelial function was assessed in the forearm skin microvasculature by acetylcholine stimulation and laser Doppler flowmetry, before and after atorvastatin treatment. Serum lipids, plasma endothelin-1 (ET-1), nitric oxide (NO), and von Willebrand factor (vWF) were also measured.

RESULTS

Both total and LDL cholesterol were significantly reduced by 26.8 +/- 8.4 and 41.5 +/- 11.0% respectively, after 4 weeks of treatment. Endothelial function was significantly improved during atorvastatin treatment, area under the flux versus time curve (AUC)(ACh) was 538 +/- 362 AU x min before and 682 +/- 276 AU x min after treatment (P=0.042). Plasma NO levels also showed a borderline significant increase from 49 +/- 30 to 57 +/- 37 micromol/l during the treatment period (P=0.051), though plasma ET-1 (0.37+/-0.08 vs 0.37+/-0.12 fmol/ml) and vW (196+/-57 vs 197+/-37%) were unchanged.

CONCLUSION

Atorvastatin lowered serum cholesterol significantly and improved endothelial function in renal transplant recipients after 4 weeks of treatment. Plasma NO levels were increased during atorvastatin treatment, indicating a possible endothelial protective effect through an "endothelial-NO pathway".

Better microvascular function on long-term treatment with lisinopril than with nifedipine in renal transplant recipients

BACKGROUND

The prevalence of hypertension in renal transplant recipients is high but the pathophysiology is poorly defined. Impaired endothelial function may be a factor of major importance. The present study addresses the effects of long-term treatment with either lisinopril or slow-release nifedipine on microvascular function and plasma endothelin in renal transplant recipients on cyclosporin A (CsA).

METHODS

Seventy-five hypertensive renal transplant recipients were double-blind randomized to receive slow-release nifedipine (NIF, n=40) or lisinopril (LIS, n=35). Ten normotensive, age-matched recipients served as controls. All patients received CsA-based immunosuppressive therapy including prednisolone and azathioprine. Microvascular function was assessed in the forearm skin vasculature, using laser Doppler flowmetry in combination with post-occlusive reactive hyperaemia and endothelial-dependent function during local acetylcholine (ACh) stimulation.

RESULTS

The analysis of microvascular function (AUC(rh)) showed that nifedipine-treated patients had significantly lower responses compared with lisinopril-treated patients (20+/-17 and 43+/-20 AU x min respectively, P=0.0016). Endothelial function was borderline significantly lower in the NIF group compared with the LIS group (640+/-345 and 817+/-404 AU x min respectively, P=0.056). The responses in the LIS group were comparable with those in non-hypertensive controls (AUC(rh) was 37+/-16 and AUC(ACh) was 994+/-566 AU x min). Plasma endothelin-1 concentrations were significantly higher in the NIF group compared with the LIS group (0.44+/-0.19 vs. 0.34+/-0.10 fmol/ml respectively, P=0.048), and were 0.29+/-0.09 fmol/ml in the control patients. AUC(ACh) was associated with plasma endothelin-1 (P=0.0053), while AUC(rh) was not (P=0.080).

CONCLUSIONS

The study indicates that long-term treatment with lisinopril, when compared with nifedipine, yields a more beneficial effect on microvascular function in hypertensive renal transplant recipients on CsA. The beneficial microvascular effect may be mediated in part by an endothelin-1-associated effect on the endothelium.

[Acute dialysis-dependent renal failure at the Rikshospital in 1998]

BACKGROUND

There are few epidemiological studies on acute renal failure, and as far as we know none have previously been conducted in Norway. The objective of this study was to evaluate the scope, etiology, treatment and results of dialysis-dependent acute renal failure based on data from the Norwegian National Hospital in 1998.

MATERIAL

This study is based on data from a questionnaire applied to all patients (n = 44) treated with dialysis for acute renal failure at the Norwegian National Hospital in 1998. The questionnaire was designed by a group of Norwegian nephrologists in cooperation with the Norwegian Society of Nephrology.

RESULTS

The incidence of dialysis-dependent acute renal failure was 54.4 per million population. Men constituted 75% of the patient population. The most common underlying disorders were heart disease, peripheral vascular disease, and cancer. 90% of patients had oliguric acute renal failure, most frequently due to postoperative complications, septicaemia or drugs, and in most cases the aetiology was multifactorial. Patients received on average nine intermittent hemodialysis treatments and stayed on average ten days in the intensive care unit. 30% of the patients were either heart, lung, liver or bone marrow transplanted (renal transplant patients were excluded). The 60 day mortality rate was 41%.

INTERPRETATION

The incidence of dialysis-dependent acute renal failure was relatively high in the Norwegian National Hospital patient pool, combined with a significant mortality rate. These findings are comparable with those of other studies.

Detection of an unusual combination of mutations in the HFE gene for hemochromatosis

In the present paper, we describe an individual, found as part of a screening study, being homozygous for the C282Y mutation and at the same time heterozygous for the H63D mutation in the HFE gene. Identical results were obtained by three different methods, i.e., by PCR-RFLP, by sequencing, and by melting curve analysis. Thus, the common conception that the C282Y and the H63D mutations are mutually exclusive is not valid. Clinical symptoms and laboratory data on the individual were similar to hemochromatosis patients homozygous for the C282Y mutation. The implications of our finding for diagnostic analytical laboratory procedures are briefly discussed.

5569G/A polymorphism of the HFE gene: no implications for C282Y genotyping in a hemochromatosis screening study of 65,238 individuals

In a previous hemochromatosis screening study including a total of 65,238 individuals, 566 persons were genotyped for the C282Y and the H63D mutations. Of these, a total of 433 samples (298 homozygous C282Y and 135 homozygous wild type) were reanalyzed to investigate if the potential presence of the newly described 5569G/A polymorphism had confounded the genotyping results for the C282Y mutation. Genotyping with a polymorphism-insensitive primer pair yielded no samples that altered their genotype. By utilizing the polymorphism-sensitive primer pair and elevated annealing temperatures, 133 samples previously genotyped as heterozygous C282Y were reanalyzed to verify the presence of the polymorphism in the population studied. Out of a total of 266 chromosomes, we found the polymorphism present in 9 chromosomes, yielding an allele frequency of 0.034 in this particular subpopulation. In one of the samples, the polymorphism was present on the same DNA strand as the C282Y mutation. We conclude that in the population studied, the 5569 G/A polymorphism is present, but its presence had no implications for the outcome of the previous genotyping. Nevertheless, we recommend that C282Y genotyping by restriction endonuclease digestion of PCR products in the future should utilize a primer pair that is not influenced by the 5569G/A polymorphism.

[Metabolic interactions with statins]

BACKGROUND

Isoenzymes of the cytochrome P450 (CYP) system play a prominent role in drug metabolism, including the HMG-CoA reductase inhibitors (statins). Alteration in metabolic activity is often the underlying mechanism of clinically relevant interactions, thus it is important to make a rational assessment of the risk for metabolic interactions with statins.

MATERIAL AND METHODS

Articles covering the field of statin metabolism and related interactions were mainly searched for via PubMed.

RESULT

More than 50% of the overall CYP metabolism is mediated through the isoenzyme CYP3A4, which is the main elimination route of simvastatin, lovastatin and atorvastatin. Interaction studies reveal that simvastatin and lovastatin have the highest potential for clinically relevant interactions related to this isoenzyme, most often leading to increased efficacy/toxicity of the statin. Interactions with agents that alter the activity of CYP3A4 can also be expected for atorvastatin. Other statins are to a lesser extent dependent on CYP3A4 in their elimination. Thus, pravastatin, cerivastatin and fluvastatin have a minor potential for interactions linked to this isoenzyme. Interactions associated with CYP2C9-interference may, however, be present for fluvastatin.

INTERPRETATION

Since lipid-lowering therapy most often is life-long, the use of statins will frequently be accompanied by the use of multiple drugs, hence the importance of considering the risk for interactions when selecting statins.

CYP2D6 is involved in O-demethylation of diltiazem. An in vitro study with transfected human liver cells

OBJECTIVE

In a previous study of diltiazem (DTZ) pharmacokinetics in renal transplant patients, we speculated that a polymorphic enzyme could be involved in O-demethylation of diltiazem. The aim of this in vitro study was to investigate whether O-demethylation of DTZ is mediated by cytochrome P450-2D6 (CYP2D6).

METHODS

DTZ was incubated with transfected human liver epithelial (THLE) cells expressing CYP2D6 (T5-2D6 clone). Metabolism of DTZ was studied over a concentration range of 12.5-400 microM and in the presence of quinidine (a CYP2D6 inhibitor) or erythromycin (a CYP3A4 inhibitor). THLE cells lacking CYP2D6 activity (T5-neo clone) were used as control. The culture medium of the cells, in which DTZ was dissolved, was analysed for DTZ and metabolites prior to and after 8 h of incubation using high-performance liquid chromatography (HPLC, UV detection). Authentic O-demethyl-DTZ (Mx) was not available, and this metabolite was therefore not identifiable.

RESULTS

Desacetyl-O-demethyl-DTZ (M4) was exclusively produced during incubations of DTZ with THLE cells expressing CYP2D6. The rate of M4 formation was described using Michaelis Menten kinetics in the concentration range of DTZ used. Production of M4 was inhibited by quinidine, but not erythromycin. An unidentified chromatographic peak, which was interpreted to be Mx, showed the same pattern of formation as M4 both in absence and presence of inhibitors. N-demethylated metabolites, formed by CYP3A4, were not observed in any of the cell lines.

CONCLUSION

Evidence was provided in vitro that O-demethylation of DTZ is mediated by the polymorphic isoenzyme CYP2D6. Involvement of CYP2D6 in the metabolism of DTZ may have clinical implications regarding pharmacokinetic variability and interactions.

Each administration of cyclosporin A enhances skin microvascular reactivity in renal transplant recipients

Both impaired and enhanced microvascular function have been described in humans on cyclosporin A (CsA) therapy. In the present study we investigated the acute microvascular effects of a single CsA administration in renal transplant recipients on maintenance CsA therapy. Fourteen renal transplant recipients, median age 48 years (range 24-63 years), transplanted 4-12 weeks earlier, were included in this placebo-controlled, double-blinded, crossover study. All recipients had stable renal function; median serum creatinine was 116 micromol/L (range 80-184 micromol/L). Immunosuppressive therapy consisted of CsA, prednisolone, and either azathioprine or mycophenolate. Microvascular function was assessed by laser Doppler flowmetry in combination with acetylcholine (endothelium dependent) stimulation and the postocclusive reactive hyperemia test. Measurements were performed before (control) and 2.5 h following administration of CsA (Neoral) or matching placebo and repeated with reversed medication after at least 6 days. Vasodilative responses to acetylcholine stimulation were significantly higher following CsA ingestion compared with placebo. The mean change in AUC(1.5) (area under the flux versus time curve) from control to 2.5 h was 100 +/-145 for CsA and -292 +/- 140 AU x min for placebo (P = 0.047, n = 10). The postocclusive hyperemic response AUC(rh) was also significantly higher following CsA intake (39 +/- 4 AU x min) compared to placebo (30 +/- 4 AU x min) (P = 0.006, n = 12). This study shows that each dose of CsA induces a transient increase in skin microvascular reactivity in renal transplant recipients. We speculate that this might be due to the potentiation of one or several endothelial-dependent compensatory vasodilative mechanisms in the microvascular bed.

[Diagnosis of depleted iron stores--do not use s-iron]

BACKGROUND

Analysis of s-ferritin is recommended for the diagnosis of depleted iron stores, but other parameters are still in use. The objective of this study was to determine the accuracy for s-iron, s-transferrin, transferrin saturation, b-hemoglobin and erythrocyte-MCH in diagnosing depleted iron stores.

MATERIAL AND METHODS

Data was collected from the Health Study of Nord-Trøndelag, 1995-1997. Blood samples from 3029 women aged 20-45 were analysed for iron status. In absence of bone marrow aspirate, s-ferritin was used as the standard for iron deficiency.

RESULTS

Highest diagnostic accuracy was found for s-transferrin. S-iron did not contribute with significant independent information.

INTERPRETATION

S-iron should not be used in the diagnosis of depleted iron stores.

A decision analysis of thrombolytic therapy compared with standard therapy in acute ischaemic stroke

OBJECTIVES

Experts draw different conclusions on whether thrombolysis can be recommended or not for acute ischaemic stroke. A major problem is weighing the improvement in functional ability against the risk of increased mortality. We wanted to examine this uncertainty regarding thrombolysis using a systematic approach and with a strong emphasis on the patient's point of view.

METHODS

We performed a decision analysis where the base case focused on an average stroke patient. We used published probabilities for different functional outcomes after standard supportive care and after adding tissue plasminogen activator (tPA), and we tried to estimate corresponding long-term survival. We interviewed 158 subjects with the standard gamble method to elicit their preference values (utility) for these outcomes.

RESULTS

When using the baseline data for an average stroke patient, thrombolysis with tPA was the better choice, with 48 extra quality-adjusted living days; tPA was also superior in 117 individual decision analyses, giving from 10 to 173 extra days. However, sensitivity analysis showed that these results were highly susceptible to changes in utility for major disability, probability of early death, and long-term survival after thrombolysis. To increase the gain as well as the margin of safety regarding the treatment choice, thrombolysis should be restricted to patients who assign low utility values < 0.6-0.7 to major poststroke disability (death = 0.0, good health = 1.0).

CONCLUSION

Evaluated by decision analysis, thrombolysis with tPA is on average superior to standard therapy for the few patients fulfilling the strict medical inclusion criteria. Individual incorporation of the patient's point of view narrows the indication even further.

Quality of life after cerebrovascular stroke: a systematic study of patients' preferences for different functional outcomes

OBJECTIVES

To elicit valid quality of life estimates and the highest acceptable treatment risk of different outcomes after stroke. This is a prerequisite for rational medical decision-making, especially when considering treatments like thrombolysis.

SUBJECTS

Healthy people, non-stroke medical patients and stroke survivors aged 20-84 years (n = 158)

INTERVENTIONS

Subjects were interviewed by a physician using three different methods ('standard gamble', 'time trade-off' and 'direct scaling') supported by an interactive computer program.

MAIN OUTCOME MEASURES

We measured utility, a numerical value ranging from 0.00 (death) to 1.00 (perfect health), representing the strength of the patient's preference for an outcome. When using the standard gamble method, risk is also introduced into the measurement.

RESULTS

People's preferences for stroke outcomes varied widely, and the estimates were influenced by assessment method. We found that previous stroke, marital status and age were the only independent variables influencing the utility given. Subjects in our population over the age of 45 were very comparable to the real population at risk for acute stroke regarding these three variables, and they assigned a median utility of 0.91 (10th percentile, 0.65; 90th percentile, 0.99) to a minor stroke and 0.61 (10th percentile, 0.08; 90th percentile, 0.95) to a major stroke using the standard gamble method.

CONCLUSIONS

Most people do not feel that suffering from stroke is an overwhelming catastrophe and they do not accept treatment options with very high risks.

Nonspecific microvascular vasodilation during iontophoresis is attenuated by application of hyperosmolar saline

Iontophoretic administration of acetylcholine chloride (ACh) and sodium nitroprusside (SNP) combined with laser Doppler skin blood perfusion measurements are used for determination of endothelial-dependent and -independent vasodilation. However, the method is biased by nonspecific vasodilation. The primary aim of this study was to investigate if iontophoresis-induced nonspecific vasodilation may be attenuated by addition of high molar concentrations of NaCl to the iontophoresis solutions. Secondary we investigated the applicability of 5 mol/liter NaCl solution as vehicle for ACh and SNP in this method. Skin perfusion changes were determined for iontophoresis of pure vehicles, deionized water and 5 mol/liter NaCl solution, in 12 healthy volunteers. Responses in skin perfusion to iontophoresis of ACh and SNP dissolved in both vehicles were also investigated. Addition of 5 mol/liter NaCl to deionized water significantly attenuated the nonspecific vasodilation and lowered the potential applied over the skin. The inter- and intraindividual coefficients of variation to ACh and SNP responses became, however, higher using hyperosmolar vehicle. During iontophoresis of SNP (in deionized water) we were unable to distinguish between SNP and vehicle effects. This study shows that the nonspecific vasodilation induced by iontophoresis can be attenuated by addition of 5 mol/liter NaCl, possibly due to lower electrical potential over the skin. However, the variability of the method was not improved. When deionized water was used as vehicle the effect of SNP could not be differentiated from that of the vehicle. This was not the case for ACh.

Pharmacokinetic interactions between microemulsion formulated cyclosporine A and diltiazem in renal transplant recipients

OBJECTIVE

Bilateral cyclosporin A (CsA) and diltiazem pharmacokinetic interactions have previously been investigated, however, not with the new microemulsion preconcentrate formulation of CsA (Sandimmun Neoral). In addition, the pharmacokinetic effects on the pharmacological active metabolites of diltiazem have not previously been investigated. We performed a pharmacokinetic interaction study in renal transplant recipients, measuring both unmetabolised CsA and diltiazem in addition to three of the main metabolites of diltiazem (MA, M1, M2).

METHODS

Nine CsA-treated renal transplant patients were treated with diltiazem, 90-120 mg b.i.d., for 4 weeks. Pharmacokinetic investigations were performed both before and at the end of the diltiazem treatment period. Six non-CsA-treated renal transplant patients served as controls of CsA interactions with diltiazem and its metabolites.

RESULTS

Diltiazem treatment resulted in a significant mean increase in the area under the concentration time curve (AUC) for CsA of 51(8)% (P < 0.008) and a peak concentration (Cmax) of 34(8)% (P < 0.05), without altering time to peak concentration (tmax). CsA, however, did not significantly influence diltiazem pharmacokinetics, though two of the metabolites (M1 and M2) tended to be increased.

CONCLUSIONS

Diltiazem interacts significantly with the pharmacokinetics of CsA in the new microemulsion formulation. Microemulsion-formulated CsA, however, did not show significant interaction with diltiazem pharmacokinetics.

A simple and sensitive high-performance liquid chromatography assay of diltiazem and main metabolites in renal transplanted patients

A sensitive and specific reversed-phase high-performance liquid chromatographic method was developed for determination of the benzothiazepine calcium channel blocker diltiazem and three of its main metabolites in human plasma. A solid-phase extraction method (C18) is described for isolating diltiazem and the metabolites N-demethyl-diltiazem (M(A)), deacetyldiltiazem (M1) and N-demethyl-deacetyl-diltiazem (M2) from human plasma spiked with trans-diltiazem as internal standard. Chromatographic analysis of the eluate was accomplished using a reversed-phase column (C8) and a mobile phase consisting of acetonitrile, potassium dihydrogen phosphate-buffer (pH 2.9), triethylamine and methanol (280:598:2:90 v/v/v/v). The limit of detection was 5 ng/ml for diltiazem and 2.5 ng/ml for the metabolites (UV detection). Recoveries were > 75% for all substances. Precision analysis indicated a coefficient of variation below 5% for both diltiazem and metabolites at plasma concentrations ranging from 30 to 120 ng/ml for diltiazem and from 15 to 60 ng/ml for the metabolites. The accuracy was < 3% for diltiazem at all concentrations investigated. Metabolites showed an accuracy of < 7% at higher concentrations, however at low concentration the accuracy was < 16%. A pilot study has been performed in order to study whether the method was applicable to patients and volunteers. Plasma samples from renal transplanted patients treated with cyclosporin A and healthy volunteers did not show any interference by cyclosporin A with the determination of diltiazem and metabolites.

Gene expression of the renal endothelin system in renal transplant recipients on cyclosporine A based immunosuppression

BACKGROUND

Immunosuppressive therapy based on cyclosporine A (CsA) is potentially nephrotoxic, and each dose of CsA is followed by a transient increase in plasma endothelin (ET)-1. The aim of this study was to investigate the effect of CsA based immunosuppressive therapy on renal gene expression of the ET(A) and ET(B) receptor subtypes and preproET-1 in human transplant needle biopsies.

METHODS

Twelve living donor renal transplant recipients, median age 51.5 years (range 24-63 years) were included in the study. Immunosuppressive therapy consisted of CsA, azathioprine, and prednisolone. Baseline renal cortical needle biopsies from the living donor kidneys were obtained just before nephrectomy. Follow-up biopsies were obtained from the same transplanted kidneys after 2-6 weeks of immunosuppressive therapy. We used a quantitative, competitive reverse transcriptase polymerase chain reaction assay to measure renal ET(A) and ET(B) receptor subtype mRNAs as well as preproET-1 mRNA levels in each of the biopsies.

RESULTS

The renal ET system was not significantly altered by CsA-based immunosuppressive therapy. Median ET(A) mRNA level was 185 (range 35-244) at baseline, and 120 (11-189) amol/microg total RNA after CsA based immunosuppressive therapy (P=0.11). ET(B) mRNA level was 506 (209-1411) at baseline, and 463 (267-1609) amol/microg total RNA at follow-up (P=0.44) and preproET-1 mRNA level was 160 (112-392) before and 221 (187-361) amol/microg total RNA after immunosuppressive therapy based on CsA (P=0.58).

CONCLUSION

This study indicates that 2-6 weeks of CsA-based immunosuppression neither significantly influences renal gene expression of the ET(A) or ET(B) receptor subtypes nor preproET-1 in living donor renal transplant kidneys.

Pulmonary hemodynamics and plasma endothelin-1 during hypoxemia and reoxygenation with room air or 100% oxygen in a piglet model

The immediate effect on the pulmonary circulation of reoxygenation with either room air or 100% O2 was studied in newborn piglets. Hypoxemia was induced by ventilation with 8% O2 until base excess was <-20 mmol/L or mean arterial blood pressure was <20 mm Hg. Reoxygenation was performed with either room air (n = 9) or 100% O2 (n = 9). Mean pulmonary artery pressure increased during hypoxemia (p = 0.012). After 5 min of reoxygenation, pulmonary artery pressure increased further from 24 +/- 2 mm Hg at the end of hypoxemia to 35 +/- 3 mm Hg (p = 0.0077 versus baseline) in the room air group and from 27 +/- 3 mm Hg at the end of hypoxemia to 30 +/- 2 mm Hg (p = 0.011 versus baseline) in the O2 group (NS between groups). Pulmonary vascular resistance index increased (p = 0.0005) during hypoxemia. During early reoxygenation pulmonary vascular resistance index decreased rapidly to values comparable to baseline within 5 min of reoxygenation in both groups (NS between groups). Plasma endothelin-1 (ET-1) decreased during hypoxemia from 1.5 +/- 0.1 ng/L at baseline to 1.2 +/- 0.1 ng/L at the end of hypoxemia (p = 0.003). After 30 min of reoxygenation plasma ET-1 increased to 1.8 +/- 0.3 and 1.5 +/- 0.2 ng/L in the room air and O2 groups, respectively (p = 0.0077 in each group versus end hypoxemia; NS between groups). We conclude that hypoxemic pulmonary hypertension and plasma ET-1 normalizes as quickly when reoxygenation is performed with room air as with 100% O2 in this hypoxia model with newborn piglets.

Glipizide treatment of post-transplant diabetes does not interfere with cyclosporine pharmacokinetics in renal allograft recipients

BACKGROUND

Glipizide is an oral antidiabetic drug that has been used in the treatment of post-transplant diabetes mellitus (PTDM). However, a published case report has indicated a possible interaction of glipizide with cyclosporine (CsA) pharmacokinetics in two renal transplant (tx) patients. The aim of this open prospective study was to investigate whether glipizide interacts with CsA pharmacokinetics in renal tx patients with PTDM.

METHODS

Eleven renal tx patients (29-74 years of age) with PTDM who received Sandimmun Neoral as part of their immunosuppressive therapy were investigated. No patients had suffered any significant rise in serum creatinine (20%) from any cause over the last 2 wk before the study. Mean S-creatinine was 137 mumol/L (87-220). The mean CsA dose and whole blood concentration remained unchanged during the study. CsA whole blood concentrations were monitored over 12 h in all patients in random order, both on and off glipizide treatment. Blood samples were drawn immediately before the morning dose of CsA was given (trough) and 0.5, 1, 1.5, 2, 3, 4, 6 and 12 h after administration.

RESULTS

Whole blood trough CsA concentration was not altered by glipizide treatment, 256 +/- 76 micrograms/L off and 242 +/- 73 micrograms/L (mean +/- SD) with glipizide coadministration. The area under the curve (AUC) and terminal half-life of CsA remained unchanged with glipizide treatment: 6391 +/- 1483 micrograms/L per h and 7.3 +/- 1.5 h without; and 6279 +/- 1601 micrograms/L per h and 7.1 +/- 1.8 h with glipizide, respectively. No change in the CsA peak concentration (Cmax) was observed: 1507 +/- 406 micrograms/L without and 1469 +/- 538 micrograms/L with glipizide coadministration.

CONCLUSION

CsA pharmacokinetics is not significantly altered by glipizide coadministration.

Diltiazem modulates cyclosporin A induced renal hemodynamic effects but not its effect on plasma endothelin-1

Cyclosporin A (CsA) has been reported to induce major acute renal hypoperfusion that may be antagonised by calcium channel blockers. The vasoconstrictive peptide endothelin-1 (ET-1) has been proposed as a mediator of CsA induced hypoperfusion. We investigated the acute effects of the new CsA formulation (Sandimmun Neoral) in 8 renal transplant patients on triple immunosuppressive therapy before and following slow-release diltiazem treatment in a dose of 90-120 mg b.i.d for 4 weeks. CsA significantly increased mean arterial blood pressure by 6 +/- 2 mmHg (p < 0.05) during the first 3 h after administration. This effect was abolished by diltiazem treatment, also reducing blood pressure by 12 +/- 3 mmHg (p < 0.05) 3-9 h after administration. CsA administration induced a maximum reduction in renal blood flow of 20 +/- 8% (p < 0.05) 5 h after ingestion and a concomitant reduction in glomerular filtration rate of 18 +/- 7% (p < 0.05). The filtration fraction increased by a maximum of 13 +/- 7% (p < 0.05) after 4 h as did the calculated fractional proximal reabsorption by 14 +/- 4% (p < 0.05). All these acute renal effects were abolished by diltiazem administration. Concurrent with the maximum renal hemodynamic effects, plasma ET-1 was elevated with a peak increase of about 40% 4-5 h after CsA ingestion. Diltiazem treatment had no effect on the increase in plasma ET-1 following CsA administration. These findings suggest that CsA induced acute vasoconstriction and renal hypoperfusion are mediated by ET-1 and that diltiazem treatment abolishes these pharmacodynamic effects of CsA despite persistent increase of plasma ET-1 levels.

Quantification of mRNA levels of endothelin receptor subtypes and preproEndothelin-1 in renal needle biopsies by competitive reverse transcriptase polymerase chain reaction

The vasoconstrictive peptide endothelin-1 (ET-1) is an autocrine/paracrine peptide of putative pathophysiological importance in renal transplant medicine. The aim of the present study was to develop a method for analysis of gene expression of the renal endothelin system in humans. Only small amounts of tissue are available from renal cortical needle biopsies. Thus, in the present study we developed a quantitative assay based on the competitive reverse transcriptase polymerase chain reaction (RT-PCR) technology. We quantified endothelin A (ET(A)) and B (ET(B)) receptor subtype mRNAs and preproET-1 mRNA levels in renal cortex biopsies obtained before nephrectomy of healthy kidney donors. Mean (+/- SEM) mRNA levels of the ET(A) and ET(B) receptor subtypes in 26 living donors were 212 +/- 23 and 368 +/- 56 amol/microg total RNA, respectively. The preproET-1 mRNA level in 19 living donors was 213 +/- 28 amol/microg total RNA. The inter-assay coefficient of variation (CV) for the assay was 10%; the intra-assay CV was 6-13%. The competitive RT-PCR assay described provides an accurate tool for gene expression investigation of the human endothelin system in renal cortical needle biopsies.

Use and usefulness of laboratory handbooks

The aim of this study was to investigate how reference handbooks distributed by hospital laboratories are used by medical doctors, and to what extent this kind of information can influence or change doctors' work habits. We also wanted to see if books with various contents of information are valued differently by the users, and we asked for preferences for an ideal book. A questionnaire was sent to 2075 medical doctors served by five Norwegian hospital laboratories. The overall response rate was 66%, of whom 76% had received a handbook. Seventy-eight percent of respondents who stated that they had received a handbook kept it in their consulting room and 45% used it once or more weekly. The majority (89%) found the books beneficial in their everyday work. Many doctors (36%) claimed that they had changed their routines as a result of the information in the book. The way of interpreting test results was influenced most often, followed by indications for ordering laboratory tests, sample collection and specimen handling, and patient preparation. Nearly all respondents (97%) felt that handbooks of this kind are beneficial to their technical and nursing staff. The results show that handbooks distributed by medical laboratories are well received, frequently used and highly appreciated by medical doctors. Comprehensive books are rated higher than smaller books.

The accuracy of C-reactive protein in diagnosing acute appendicitis--a meta-analysis

The aim of the study was to review the literature on the accuracy of C-reactive protein (CRP) in diagnosing acute appendicitis. All the relevant articles found by searching Medline and the Science Citation Index were reviewed. We used summary receiver operating characteristic (SROC) curve analysis to describe the central tendency of the studies and to assess potential sources of variability. We included 22 articles with a total number of 3436 patients. The sensitivity ranged from 0.40 to 0.99, and the specificity from 0.27 to 0.90. The cut-off values for a positive test varied from 5 to 25 mg l-1. SROC curve analysis showed that CRP performed significantly better in acute abdomen populations (11 studies) than in populations already selected for appendectomy (11 studies). The diagnostic accuracy of CRP tended to be a little inferior to that of total leukocyte count (13 studies). CRP is a test of medium accuracy in diagnosing acute appendicitis. The formerly distractingly wide range of sensitivity and specificity is at least partly due to variations in cut-off values and to differences in study populations. However, definitive conclusions on the clinical usefulness of the test could not be drawn.

Additional value of biochemical tests in suspected acute appendicitis

OBJECTIVE

To evaluate the efficacy of biochemical tests in diagnosing acute appendicitis.

DESIGN

Open prospective study.

SETTING

District hospital, Norway.

SUBJECTS

257 patients with suspected acute appendicitis.

INTERVENTIONS

Initial diagnostic accuracy of a logistic regression model using available clinical data was compared with results of corresponding models that included an increasing number of inflammatory parameters.

MAIN OUTCOME MEASURES

The estimated probabilities of appendicitis in different testing groups were analysed using receiver operating characteristic (ROC) curves.

RESULTS

A model including only clinical variables had a mean area under the ROC curve of 0.854. When the total white blood cell count, C-reactive protein concentration, and neutrophil count were added, the model improved significantly to 0.920.

CONCLUSION

Biochemical tests are of additional value in a computer model, and the tests should, if used rationally, also provide physicians with important information in the investigation of acute appendicitis.