Impact of Renal Denervation on Urinary Peptide-Based Biomarkers in Hypertension

BACKGROUND

Catheter-based renal denervation (RDN) reduces blood pressure in hypertension. Urinary peptides are associated with cardiovascular and renal disease and provide prognostic information. We aimed to investigate the effect of RDN on urinary peptide-based biomarker panels associated with chronic kidney and heart disease and to identify urinary peptides affected by RDN.

METHODS

This single-arm, single-center study included patients undergoing catheter-based RDN. Urine samples were collected before and 24 months after RDN and were analyzed using capillary electrophoresis coupled with mass spectrometry. Predefined urinary peptide-based biomarker panels for chronic kidney disease (CKD273), coronary artery disease (CAD238), and heart failure (HF1) were calculated.

RESULTS

This study included 48 patients (33% female) with uncontrolled hypertension. At 24 months after RDN, systolic blood pressure (165±17 versus 148±20 mm Hg; P<0.0001), diastolic blood pressure (90±17 versus 81±13 mm Hg; P<0.0001), and mean arterial pressure (115±15 versus 103±13 mm Hg; P<0.0001) decreased significantly. A total of 103 urinary peptides from 37 different proteins, mostly collagens, altered following RDN. CAD238, a 238 coronary artery-specific polypeptide pattern, significantly improved following RDN (Cohen's d, -0.632; P=0.0001). The classification scores of HF1 (P=0.8295) and CKD273 (P=0.6293) did not change significantly.

CONCLUSIONS

RDN beneficially affected urinary peptides associated with coronary artery disease.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01888315.

Effects of Renal Denervation vs Sham in Resistant Hypertension After Medication Escalation: Prespecified Analysis at 6 Months of the RADIANCE-HTN TRIO Randomized Clinical Trial

Importance

Although early trials of endovascular renal denervation (RDN) for patients with resistant hypertension (RHTN) reported inconsistent results, ultrasound RDN (uRDN) was found to decrease blood pressure (BP) vs sham at 2 months in patients with RHTN taking stable background medications in the Study of the ReCor Medical Paradise System in Clinical Hypertension (RADIANCE-HTN TRIO) trial.

Objectives

To report the prespecified analysis of the persistence of the BP effects and safety of uRDN vs sham at 6 months in conjunction with escalating antihypertensive medications.

Design, Setting, and Participants

This randomized, sham-controlled, clinical trial with outcome assessors and patients blinded to treatment assignment, enrolled patients from March 11, 2016, to March 13, 2020. This was an international, multicenter study conducted in the US and Europe. Participants with daytime ambulatory BP of 135/85 mm Hg or higher after 4 weeks of single-pill triple-combination treatment (angiotensin-receptor blocker, calcium channel blocker, and thiazide diuretic) with estimated glomerular filtration rate (eGFR) of 40 mL/min/1.73 m2 or greater were randomly assigned to uRDN or sham with medications unchanged through 2 months. From 2 to 5 months, if monthly home BP was 135/85 mm Hg or higher, standardized stepped-care antihypertensive treatment starting with aldosterone antagonists was initiated under blinding to treatment assignment.

Interventions

uRDN vs sham procedure in conjunction with added medications to target BP control.

Main Outcomes and Measures

Six-month change in medications, change in daytime ambulatory systolic BP, change in home systolic BP adjusted for baseline BP and medications, and safety.

Results

A total of 65 of 69 participants in the uRDN group and 64 of 67 participants in the sham group (mean [SD] age, 52.4 [8.3] years; 104 male [80.6%]) with a mean (SD) eGFR of 81.5 (22.8) mL/min/1.73 m2 had 6-month daytime ambulatory BP measurements. Fewer medications were added in the uRDN group (mean [SD], 0.7 [1.0] medications) vs sham (mean [SD], 1.1 [1.1] medications; P = .045) and fewer patients in the uRDN group received aldosterone antagonists at 6 months (26 of 65 [40.0%] vs 39 of 64 [60.9%]; P = .02). Despite less intensive standardized stepped-care antihypertensive treatment, mean (SD) daytime ambulatory BP at 6 months was 138.3 (15.1) mm Hg with uRDN vs 139.0 (14.3) mm Hg with sham (additional decreases of -2.4 [16.6] vs -7.0 [16.7] mm Hg from month 2, respectively), whereas home SBP was lowered to a greater extent with uRDN by 4.3 mm Hg (95% CI, 0.5-8.1 mm Hg; P = .03) in a mixed model adjusting for baseline and number of medications. Adverse events were infrequent and similar between groups.

Conclusions and Relevance

In this study, in patients with RHTN initially randomly assigned to uRDN or a sham procedure and who had persistent elevation of BP at 2 months after the procedure, standardized stepped-care antihypertensive treatment escalation resulted in similar BP reduction in both groups at 6 months, with fewer additional medications required in the uRDN group.

Trial Registration

ClinicalTrials.gov Identifier: NCT02649426.

Correlation of local impedance, global impedance and contact force with resulting lesion size in RF ablation

Funding Acknowledgements

Type of funding sources: None.

Background

During clinical application of RF-energy, several parameters are constantly observed, e.g. RF time, power, global impedance and temperature. The new parameter "local impedance" is gaining importance and might be a possible real-time marker for predicting long-lasting RF-lesions and increasing safety. The aim of this study was to investigate the correlation between local and global impedance as well as RF power and contact force.

Methods

RF-lesions were created using an ex vivo model with porcine cardiac preparations. These were put in a saline-filled container with a dispersive electrode. Global impedance was held at 120 Ohm by adjusting saline and water. Additionally, a heated thermostat and a circulation pump were installed to imitate blood flow. RF-lesions were produced with different settings of energy and contact force (20, 30, 40 and 50 watts; contact force of 0-5g, 10-15g and 20-25g). While creating the lesions, global and local impedance, temperature, energy and RF time were documented, as well as the current lesion width and depth. Local and global impedance drops were calculated as the difference between baseline impedance and current impedance.

Results

In total, 1223 measurements were made during application of RF-energy. 6 steam pops occurred. Contact force, local and global impedance changes showed highly significant correlations with lesion depth and diameter. Amongst analyzed values, local impedance drop showed highest correlation with lesion diameter and depth (r = 0,391 and 0,613; p&lt;0,001). Visualized in Figure 1 and 2, global and local impedance correlate with lesion diameter and depth.

Discussion

Local impedance was found to be a suitable real-time marker for lesion size, showing significantly higher correlations with RF lesion size than contact force and global impedance. Further investigation is necessary to find a cut off for a safe but long-lasting RF-lesion.

Electrode tissue coupling is a new main determinant of RF lesion creation, experience from a cardiac animal model

Funding Acknowledgements

Type of funding sources: None.

Background

Radiofrequency (RF) current is a classic ablation technology used in the EP lab. By now it is assumed that RF lesion size is mainly determined by RF power, duration and contact force. This ex vivo animal model study shows that a new parameter - "electrode tissue coupling" (ETC) - plays an additional major role in RF lesion creation. The ETC level describes the amount of electric contact between the RF electrode and cardiac tissue: In minor ETC levels, only the distal electrode connects to tissue. In full ETC levels, the whole RF electrode is embedded in cardiac tissue.

Methods

RF-lesions were created using an ex vivo porcine cardiac model. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. RF-lesions were created using identic values of RF duration and contact force. A RF power of 20W, 30W, 40W, and 50W was used. The ETC levels were systematically varied between minor and full coupling. All parameters (power, temperature, global and local impedance, contact force, ETC, lesion size) were measured constantly during application of RF-current, enabling real-time correlation of RF parameters and lesion size.

Results

In total, 1923 measurements during application of RF-current were analyzed. In ETC III (full tissue coupling), lesions became significantly wider and deeper. In 20W ablations, lesion diameters were significantly (1.68 fold) larger when applying ETC III instead of ETC I. This relation was found in variations of RF parameters (Table 1).

Interestingly, baseline local impedance and local impedance drop showed a high correlation with selected ETC levels. The average baseline local impedance in ETC I was 207.2 Ohm, compared to 267.3 Ohm in ETC III (p &lt; 0.01).

Discussion

In addition to by now known parameters (power, duration, contact force), electrode tissue coupling is a main determinant of lesion size. Higher ETC levels result in higher amounts of RF current going into adjacent tissue instead of current dissipation into the blood pool. In clinical practice, the ETC level can be predicted by baseline local and global impedance. Observation of these parameters should become clinical practice during RF ablation.

P–253 Description of a rare spontaneous monozygotic blastocyst splitting into two discrete euploid blastocysts in vitro detected with time-lapse imaging and preimplantation genetic testing (PGT)

Study question

Can spontaneous and complete blastocyst splitting into two, in vitro, be investigated using time-lapse imaging and biopsy of each trophectoderm, for inference of ploidy?

Summary answer

Time-lapse imaging combined with PGT-A gives insights into the incidence, dynamics and timing of rare blastocyst splitting and the ploidy status of each resulting blastocyst.

What is known already

It is well known that multiple births occur more often with Assisted Reproductive Technologies (ART) than spontaneous conception, even after single embryo transfer. The mechanism of Monozygotic Twinning (MZT) during ART is still unclear but cryopreservation, extended culture, PGT, maternal age and assisted hatching are reported risk factors. MZT is a rare phenomenon, with an incidence of 0.4% in natural conception compared with up to 4.9% in ART. The timing of embryo splitting dictates the type of twinning, in terms of chorionicity and amnionicty, and this is officially determined using ultrasound scanning.

Study design, size, duration

This is a case study describing the detection of the complete splitting of an IVF blastocyst at 140 hours post insemination (hpi), using time-lapse imaging.

The 40-year-old patient previously experienced biochemical pregnancy and several miscarriages; an ectopic molar pregnancy and a probable cornual ectopic. The 39-year-old male partner was normozoospermic.

Participants/materials, setting, methods

Facilitative laser breaching was performed, according to standard operating procedure, of the morula at 96hpi of embryo development, prior to PGT. Images were collected every 10 minutes and developmental events and embryos morphology annotated using the EmbryoScope+™ time lapse incubator and software.

Main results and the role of chance

Over 50,000 hatching blastocysts have been time-lapse imaged, scrutinised and annotated within this group of fertility clinics. This is the first time that such a rare blastocyst splitting event has been recorded and studied.

Following observation of two pronuclei following IVF and typical cleavage development to blastocyst, with facilitative zona breaching on, at 106.7hpi, the full blastocyst’s trophectoderm (TE) began to herniate and hatch. By 114.3hpi a second internal blastocoel cavity formed appearing to divide the inner cell mass (ICM) within the zona pellucida (ZP). This resulting blastocyst proceeded to hatch as its discrete ICM migrated out of the ZP, along with its TE. TE cells from the original blastocyst then began to hatch at 117.5hpi at the same breached site in the ZP with its ICM visibly evacuating the ZP.

By 140hpi the blastocyst had split into two discrete blastocysts while hatching from the ZP. Both resulting blastocysts had clear and separate ICMs and TEs present. Biopsy of approximately 5 cells was performed for each TE, and the blastocysts were vitrified individually. Next Generation Sequencing (NGS) reported both blastocysts to be euploid.

Limitations, reasons for caution

This case may have been detectable without time-lapse imaging, as the splitting was completed prior to biopsy. More expert scrutiny of the images may result in earlier signs of twinning in progress being detected.

Wider implications of the findings: The nature of this detectable in vitro blastocyst splitting, indicates these embryos (if they implanted) to be monozygotic, dichoriol-diamniotic ‘identical’ twins. However – as single embryo transfer is the preferred treatment plan; they may be born years apart. These observations could shed light on the debated models of monozygotic twinning.

Trial registration number

Not applicable

P–164 Mulitcentre derived time lapse algorithms developed using 6228 transferred embryos with known birth outcome incorporating novel morphological and morphokinetic markers

Study question

Can incorporation of novel markers of morphology with known temporal events successfully rank embryos to enable prediction of propensity for live birth?

Summary answer

Incorporation of variables for trophectoderm and morula grading demonstrably enhanced the model to rank embryos in order of potential for live birth.

What is known already

Models built using morphokinetic markers of development are widely used to rank embryos within a cohort. Such models include defined temporal parameters which are closely related to morphological grade. However, morphological grading by an embryologist is subjective and is not strongly correlated to outcome. Combining with defined kinetic events has been suggested to improve prediction of outcome.

Study design, size, duration

Data from 6228 known live birth outcome embryos from 8 UK clinics between 2011 – 2018 were investigated using an exploratory approach to identify novel markers of development.

Participants/materials, setting, methods

Five significant variables were defined, a derivative of time to start of blastulation; a derivative of trophectoderm grade; a kinetic variable utilising t3, t4, t5 and t8; an interval variable of tB-tSB and a variable based on novel morula classification. To maximise the output, a proxy value was derived for missing datapoints. The model was built using logistical regression and validated using fivefold cross validation with the data split as 80% training and 20% test.

Main results and the role of chance

An algorithm was developed including the five significant variables identified with an AUC of 0.685 demonstrating reliable prediction of live birth. Without morphological variables, the AUC was 0.674 demonstrating the improvement in the prediction value by including the derivative of the trophectoderm and morula grade. This resulted in ten classes of algorithm scores, 1–10, giving a live birth rate from 2% to 46%, irrespective of patient variables, for chance of live birth.

Limitations, reasons for caution

Successful application of the algorithm is reliant on stringent quality assurance for maintenance of accurate annotation and grading, and may not be transferable between laboratories with different SOPs.

Wider implications of the findings: The addition of a trophectoderm and morula grade in combination with morphokinetic parameters, increases the predictive value of the algorithm in relation to live birth outcome. Using proxy values allows maximization of data for model generation, and allows the model to be applied when missing values are present.

Trial registration number

Not applicable

PHARMacy-based interdisciplinary program for patients with Chronic Heart Failure (PHARM-CHF): rationale and design of a randomized controlled trial, and results of the pilot study

We report the rationale and design of a community PHARMacy-based prospective randomized controlled interdisciplinary study for ambulatory patients with Chronic Heart Failure (PHARM-CHF) and results of its pilot study. The pilot study randomized 50 patients to a pharmacy-based intervention or usual care for 12 months. It demonstrated the feasibility of the design and showed reduced systolic blood pressure in the intervention group as indicator for improved medication adherence. The main study will randomize patients ≥60 years on stable pharmacotherapy including at least one diuretic and a history of heart failure hospitalization within 12 months. The intervention group will receive a medication review at baseline followed by regular dose dispensing of the medication, counselling regarding medication use and symptoms of heart failure. The control patients are unknown to the pharmacy and receive usual care. The primary efficacy endpoint is medication adherence, pre-specified as a significant difference of the proportion of days covered between the intervention and control group within 365 days following randomization using pharmacy claims data for three CHF medications (angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, beta-blockers, and mineralocorticoid receptor antagonists). The primary composite safety endpoint is days lost due to blindly adjudicated unplanned cardiovascular hospitalizations or death. Overall, 248 patients shall be randomized. The minimum follow-up is 12 months with an expected mean of 24 months. Based on the feasibility demonstrated in the pilot study, the randomized PHARM-CHF trial will test whether an interdisciplinary pharmacy-based intervention can safely improve medication adherence and will estimate the potential impact on clinical endpoints. ClinicalTrials.gov Identifier: NCT01692119.

Do patients with diabetes type 2 or chronic heart failure understand a medication plan?

A standardized medication plan (MP) was recently enacted into German law (§ 31a SGB V). The purpose of our study was to assess if patients with chronic diseases requiring polymedication understand the standardized MP and can transfer the given information into practice. 100 patients who took at least five medicines regularly were prospectively included in a cross-sectional study: 50 patients with the primary diagnosis chronic heart failure (CHF), and 50 with diabetes mellitus type 2 (DMT2). We performed a structured test-scenario studying the handling of a provided MP then evaluated the execution of the information on the MP by filling pill boxes and requested patients' opinion. An established weighted scoring system, the "Evaluation Tool to test the handling of the Medication Plan" (ET-MP) was applied to quantitate the ability of the patients to handle the MP. In addition, signs of depression, cognitive function and self-care behavior in chronic heart failure were characterized using the PHQ-9, Mini-Cog, and G9-EHFScB-9 questionnaires, respectively. The understanding of the MP was poor and irrespective of the underlying primary diagnosis. Only 32% of all patients were able to handle the MP without difficulties (ET-MP score >90%), the median ET-MP score was 83 [(IQR) 50-98]. Comprehension of the MP was better in patients aged <70 years compared to ≥70 years (p<0.01). Patients ≥10 years of education achieved higher ET-MP results than patients with <10 years of education (p<0.01). Patients with signs of cognitive impairment exhibited significantly lower ET-MP scores than patients without cognitive impairment (p<0.001). There were no significant correlations of the ET-MP score with number of daily medications, living situation, sex, the Charlson Comorbidity Index, the PHQ-9 score, and use of a dosing aid or possession of a medication list.

A computational model of a human single sinoatrial node cell

For the investigation of the spontaneous rhythmical activity response in the application of cardiac neuromodulation, we formulated a human sinoatrial node (SAN) cell model. With the aim of decreasing elevated heart rate (HR), we want to establish a hardware-in-the-loop system including this model for the analysis of optimal stimulation patterns of the neurostimulation system. Base model structures are adopted from rabbit SAN cell models available in literature and conveyed with Hodgkin-Huxley-type model equations describing the complex time and voltage dependent activation and deactivation processes of individual ion channels. The resulting model consists of 15 currents which are currently known to be responsible for the generation of the membrane action potential (AP). The model reproduces AP frequencies equivalent to those measured in isolated human SAN cells with a resulting HR of 71.8 bpm. Model validation via simulation of the inhibitory effect of ivabradine showed accordance with experimental results obtained in human studies. Furthermore, we could validate the model in regard to its HR effects upon parasympathetic stimulation with results obtained in a human trial study.

Medication knowledge of patients hospitalized for heart failure at admission and after discharge

BACKGROUND

A substantial aspect of health literacy is the knowledge of prescribed medication. In chronic heart failure, incomplete intake of prescribed drugs (medication non-adherence) is inversely associated with clinical prognosis. Therefore, we assessed medication knowledge in a cohort of patients with decompensated heart failure at hospital admission and after discharge in a prospective, cross-sectional study.

METHODS

One hundred and eleven patients presenting at the emergency department with acute decompensated heart failure were included (mean age 78.4±9.2, 59% men) in the study. Patients' medication knowledge was assessed during individual interviews at baseline, course of hospitalization, and 3 months after discharge. Individual responses were compared with the medical records of the referring general practitioner.

RESULTS

Median N-terminal prohormone of brain natriuretic peptide plasma concentration in the overall population at baseline was 4,208 pg/mL (2,023-7,101 pg/mL [interquartile range]), 20 patients died between the second and third interview. The number of prescribed drugs increased from 8±3 at baseline to 9±3 after 3 months. The majority of patients did not know the correct number of their drugs. Medication knowledge decreased continuously from baseline to the third interview. At baseline, 37% (n=41) of patients stated the correct number of drugs to be taken, whereas only 18% (n=16) knew the correct number 3 months after discharge (P=0.008). Knowledge was inversely related to N-terminal prohormone of brain natriuretic peptide levels.

CONCLUSION

Medication knowledge of patients with acute decompensated heart failure is poor. Despite care in a university hospital, patients' individual medication knowledge decreased after discharge. The study reveals an urgent need for better strategies to improve and promote the knowledge of prescribed medication in these very high-risk patients.

Novel insight into the regulation of GSH biosynthesis in higher plants

In higher plants, the redox-active tripeptide glutathione (GSH) fulfills a plethora of functions. These include its pivotal role for maintaining the cellular redox poise and its involvement in detoxification of heavy metals and xenobiotics. Intimately linked to these functions, GSH also acts as a cellular signal, mediating control of enzyme and/or regulatory protein activities, either directly or via glutaredoxins. The redox potential of the GSH/GSSG couple is not only affected by the GSH/GSSG ratio but also by changes in GSH synthesis and/or degradation. As this couple operates as redox buffer in several cellular compartments, the regulation of GSH biosynthesis and transport (both intra- and intercellularly) are fundamental to the maintenance of cellular redox homeostasis during plant development and, even more so, when plants are exposed to biotic or abiotic stress. This review highlights novel aspects of GSH biosynthesis and transport with a focus on the regulation of the GSH1 (= gamma-glutamylcysteine synthetase) enzyme. Interestingly, GSH1 appears to be exclusively confined to the plastids, whereas the second biosynthetic enzyme, GSH2, is predominantly localized in the cytosol. GSH1 expression and enzyme activity are under multiple controls, extending from transcriptional regulation to post-translational redox control. Now that the plant GSH1 protein structure has been solved, the molecular basis of GSH1 function and redox regulation can be addressed. The review concludes with a discussion of the simultaneous changes observed for GSH synthesis, transport, and metabolism during Cd-induced phytochelatin accumulation.

[Münster age- and retina study (MARS). Association between risk factors for arteriosclerosis and age-related macular degeneration]

BACKGROUND

The association between arteriosclerosis and age-related macular degeneration (AMD) has only been examined in a few studies and the data is still very inconsistent.

METHODS

A cross sectional study was initiated with 730 patients from the Münster age and retina study (MARS) which examines patients in the age range 60 to 80 years old who were referred by ophthalmologists from the Muenster area. Patients with narrow angle glaucoma were excluded. All patients underwent a standardized ophthalmoscopic examination und were classified into four groups: group 1 without AMD ( n=190), group 2 with unilateral or bilateral early forms of AMD ( n=340), group 3 with unilateral late forms of AMD ( n=139) and group 4 with bilateral late forms of AMD ( n=50). By means of these groups it was tested if there was a significant difference between the different risk factors for arteriosclerosis.

RESULTS

The mean age was 72 years and 58% were women and the sex distribution within the different groups did not differ significantly (all trend tests with p>0.1). General risk factors for arteriosclerosis such as diabetes, body-mass-index and hypertension did not differ significantly (all trend tests with p>0.1). The number of smokers increased significantly with the severity of AMD ( p=0.02). Furthermore, various lipids were examined, adjusted for age and sex and showed significant decrease of HDL ( p=0.087) and significant increases of the HDL/LDL quotient ( p=0.0007) and the non-sober triglyceride values ( p=0.0058) correlated with the severity of AMD.

CONCLUSIONS

There was a highly significant, direct association of indicators of dyslipidemia such as increasing HDL/LDL quotient and decreasing HDL with the severity of AMD. These results were underlined by increased triglyceride levels even if they were taken non-sober. The results must be interpreted with caution due to the explorative character of the evaluation.

Blood flow velocities in the basal vein after subarachnoid haemorrhage. A prospective study using transcranial duplex sonography

BACKGROUND

Early recognition of emerging delayed neurological deficits (DND) in patients after subarachnoid haemorrhage (SAH) is not always possible by transcranial Doppler sonography. Aim of this study was to investigate a) whether determination of blood flow velocities in deep cerebral basal veins can predict DND in these patients b) the correlation of venous flow velocity to cerebral blood flow (CBF).

METHODS

a) We prospectively investigated the mean flow velocity in the basal vein (VBVR), in the middle cerebral artery (VMCA) and in the extracranial internal carotid artery (VICA) in 66 patients after spontaneous SAH. Examinations were performed daily during the first 10 days, using transcranial duplex sonography. Thirty-seven patients had VMCA exceeding 120 cm/s. They were categorised in three groups: 1: no delayed neurological deficit; II: transient DND; III: permanent DND or death associated with vasospasm. b) In another group of 14 patients, interdiane variations in global cerebral blood flow (CBF) measured by the Kety-Schmidt-method were correlated with variations in VBVR, VMCA, and VICA.

FINDINGS

a) In patients without deficit, VBVR was significantly elevated above normal values the first day (p < 0.05), and days 5 and 6 (p < 0.1) after VMCA exceeding 120 cm/s. In group III (permanent deficit), flow velocities in the BVR were significantly below normal on day 5 (p < 0.05) and 9 (p < 0.1). b) The correlation between changes in VBVR to changes in CBF (r = 0.78, p < 0.001) was closer than between changes in VMCA to the changes in CBF (r = 0.54, p < 0.05).

INTERPRETATION

In case of elevated VMCA, patients with higher VBVR seem to have a better outcome. Changes in CBF correlate better with VBVR than with arterial flow velocities.

Exposure of oncologic nurses to methotrexate in the treatment of osteosarcoma

Methotrexate is a therapeutic agent used widely for osteosarcoma. We used an extremely sensitive high-performance liquid-chromatography assay to evaluate 112 urine samples obtained from 28 hospital employees during high-dose therapy with methotrexate and during routine care of patients. The highest cumulative urinary excretion was observed when methotrexate infusions were handled in a workbench from which a portion of filtered air was emitted into the room. Remarkable urine contaminations were identified for personnel, including 1 administrative employee who had "stood by" for 2 h in the room where infusions were prepared. Lower methotrexate concentrations were detected in the urine of nurses whose exclusive function was to care for patients. The urine burden in oncologic nurses decreased after a central pharmacy unit was installed. Methotrexate was excreted in the sweat of patients who were under high-dose therapy, and its elimination half-life was 11.1 h (mean maximal concentration = 1.7 micrograms/ml [n = 51). The maximal burden in spontaneous vomit from these patients was 441.5 micrograms/ml, and it declined to 0.24 micrograms/ml 19.5 h after infusion was completed. No methotrexate was detected in personnel who prepared 20-g methotrexate infusions in the central pharmacy unit. We demonstrated that occupational safety depended not only on technical precautions, but on the skills of specifically trained personnel.