Integrated thermal and magnetic susceptibility modeling for air-motion artifact correction in proton resonance frequency shift thermometry.

PURPOSE: Hyperthermia treatments are successful adjuvants to conventional cancer therapies in which the tumor is sensitized by heating. To monitor and guide the hyperthermia treatment, measuring the tumor and healthy tissue temperature is important. The typical clinical practice heavily relies on intraluminal probe measurements that are uncomfortable for the patient and only provide spatially sparse temperature information. A solution may be offered through recent advances in magnetic resonance thermometry, which allows for three-dimensional internal temperature measurements. However, these measurements are not widely used in the pelvic region due to a low signal-to-noise ratio and presence of image artifacts. METHODS: To advance the clinical integration of magnetic resonance-guided cancer treatments, we consider the problem of removing air-motion-induced image artifacts. Thereto, we propose a new combined thermal and magnetic susceptibility model-based temperature estimation scheme that uses temperature estimates to improve the removal of air-motion-induced image artifacts. The method is experimentally validated using a dedicated phantom that enables the controlled injection of air-motion artifacts and with in vivo thermometry from a clinical hyperthermia treatment. RESULTS: We showed, using probe measurements in a heated phantom, that our method reduced the mean absolute error (MAE) by 58% compared to the state-of-the-art near a moving air volume. Moreover, with in vivo thermometry our method obtained a MAE reduction between 17% and 95% compared to the state-of-the-art. CONCLUSION: We expect that the combined thermal and magnetic susceptibility modeling used in model-based temperature estimation can significantly improve the monitoring in hyperthermia treatments and enable feedback strategies to further improve MR-guided hyperthermia cancer treatments.

The role of ICP overnight monitoring (ONM) in children with suspected craniostenosis.

PURPOSE: Secondary craniostenosis is a relevant problem pediatric neurosurgeons are confronted with and poses challenges regarding reliable diagnosis of raised ICP, especially in case of absent or questionable papilledema. How to identify children with elevated ICP is still controversial and diagnostics vary. We report on our experience with computerized ICP ONM in relation to imaging derived parameters. METHODS: Thirty-four children with primary or secondary craniostenosis and clinical suspicion of raised ICP were investigated. We compared clinical signs, history, and radiographic assessment with the results of computerized ICP ONM. Differences were significant at a p < 0.05. RESULTS: Baseline ICP was significantly higher in patients with combined suture synostosis, who also had a higher rate of questionable papilledema. Children with narrowed external CSF spaces in MRI had significantly higher ICP levels during REM sleep. Mean RAP was significantly elevated in patients with multi-suture synostosis, indicating poor intracranial compensatory reserve. Syndromal craniostenosis was associated with elevated ICP, RAP was significantly lower, and skull X-rays showed more impressions (copper beaten skull). RAP increased with more severe impressions only to decline in most severe abnormalities, indicating exhaustion of cerebrovascular reserve at an upper ICP breakpoint of 23.9 mmHg. Headaches correlated to lower ICP and were not associated with more severe X-ray abnormalities. CONCLUSION: Narrowed external CSF spaces in MRI seem to be associated to elevated ICP. Skull X-rays can help to identify patients at risk for chronically elevated ICP. Severe X-ray changes correlate with exhausted cerebrovascular reserve as indicated by RAP decline. Only ICP monitoring clearly identifies raised ICP and low brain compliance. Thus, in cases with ambiguous imaging, ONM constitutes an effective tool to acquire objective data for identification of surgical candidates.

Model predictive control for MR-HIFU-mediated, uniform hyperthermia.

Purpose: In local hyperthermia, precise temperature control throughout the entire target region is key for swift, safe, and effective treatment. In this article, we present a model predictive control (MPC) algorithm providing voxel-level temperature control in magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) and assess the improvement in performance it provides over the current state of the art. Materials and methods: The influence of model detail on the prediction quality and runtime of the controller is evaluated and a tissue mimicking phantom is characterized using the resulting model. Next, potential problems arising from modeling errors are evaluated in silico and in the characterized phantom. Finally, the controller's performance is compared to the current state-of-the-art hyperthermia controller in side-by-side experiments. Results: Modeling diffusion by heat exchange between four neighboring voxels achieves high predictive performance and results in runtimes suited for real-time control. Erroneous model parameters deteriorate the MPC's performance. Using models derived from thermometry data acquired during low powered test sonications, however, high control performance is achieved. In a direct comparison with the state-of-the-art hyperthermia controller, the MPC produces smaller tracking errors and tighter temperature distributions, both in a homogeneous target and near a localized heat sink. Conclusion: Using thermal models deduced from low-powered test sonications, the proposed MPC algorithm provides good performance in phantoms. In direct comparison to the current state-of-the-art hyperthermia controller, MPC performs better due to the more finely tuned heating patterns and therefore constitutes an important step toward stable, uniform hyperthermia.

Diagnosis and treatment of chronic wounds: current standards of Germany's Initiative for Chronic Wounds e. V.

The diagnosis and treatment of patients with chronic wounds is an enormous challenge in various disciplines of medicine. These very complex processes usually involve several experts of different medical specialties with varying educational backgrounds. A necessary basis for consistent communication and documentation is the use of unambiguous nomenclature. Therefore, the board of the German wound association, Initiative for Chronic Wounds (ICW) e.V., has started to define various terms and procedures. An easy to remember algorithm, in the form of the ABCDE rule, has been developed for the structured diagnosis of chronic wounds. The successful therapy of chronic wounds is then based on the causal treatment of the underlying, pathophysiological relevant diseases. M.O.I.S.T. a concept which helps health professionals in the systematic approach to the local treatment of patients with chronic wounds, in conforming to the most up-to-date scientific knowledge. By using consistent definitions and standards in wound care, it is possible to optimise current diagnostic and treatment strategies as well as to make them more easily understandable.

Electroweak Corrections to pp→µ

The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state µ^{+}µ^{-}e^{+}e^{-}, we study differential cross sections that are particularly interesting for Higgs boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W- or Z-boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular, a sign change between the regions of resonant Z-pair production and the Higgs signal.

[German Version of the Childbirth Self-Efficacy Inventory and its Short Form]. / Deutsche Version des Childbirth Self-Efficacy Inventory und dessen Kurzform - ein Fragebogen zur Selbstwirksamkeit.

BACKGROUND: The Childbirth Self-Efficacy Inventory (CBSEI) is an instrument that measures women's perceived self-efficacy towards labour. It is used in 9 countries, a 32-item short form (CBSEI-C32) in 4 countries. German versions of the CBSEI and the CBSEI-C32 have not been developed thus far. METHODS: A forward-backward translation was performed, followed by administration of both instruments to a sample of 155 participants of antenatal classes. Pregnant women answered questions regarding their medical history and user-friendliness of the instruments. 80 respondents completed the CBSEI, 75 the CBSEI-C32. Reliability via Cronbach alpha was calculated for the 4 subscales of the CBSEI and the 2 subscales of the short form. Validity was only assessed for the 2 scales of the CBSEI-C32 because all women (n=155) completed this instrument. RESULTS: 2 Cronbach alpha values were greater than 0.74 (adequate), the others greater than 0.80 (good). Most of the factors of the CBSEI-C32 (75%) were above ≥0.5. Calculation of the item-to-total-correlations revealed that the exclusion of 3 items might be indicated for the German version. The short form showed a significant association between level of education and perceived self-efficacy (p=0.01). RESULTS in the area of user-friendliness were more encouraging for the CBSEI-C32 than for the CBSEI. CONCLUSION: The German version of the CBSEI is a useful instrument which may improve advice and counselling during prenatal care in Germany.

Chronic stress experience and burnout syndrome have appreciable influence on health-related quality of life in patients with psoriasis.

BACKGROUND: Psoriasis has a negative impact on health-related quality of life (HRQoL) and may favour mental comorbidity. OBJECTIVE: To investigate the contribution of chronic stress and burnout experience to HRQoL and how mental health influences the efficacy of an inpatient rehabilitation measure in psoriasis patients. METHODS: Eighty-four psoriasis patients taking part in a 3-week inpatient rehabilitation measure participated in the study. Severity of psoriasis was assessed with the Psoriasis Area and Severity Index (PASI) and by patients' self-evaluation at the beginning and end of treatment. The following aspects of mental health were explored using validated questionnaires. Symptoms of chronic stress and burnout experience: Trier Inventory for the Assessment of Chronic Stress (TICS) and Shirom Melamed Burnout Measure (SMBM). Symptoms of depression: depression scale of the Patient Health Questionnaire in the German version (PHQ-D). HRQoL: Dermatology Life Quality Index (DLQI) and Short Form Health Survey-8 (SF-8). RESULTS: Linear regression analyses revealed that chronic stress, burnout experience and perceived symptom severity but not clinician-assessed severity of psoriasis had independent negative effects on HRQoL. Patients who achieved a PASI reduction of <75% at discharge from the rehabilitation measure had lower baseline QoL and showed more symptoms of depression, chronic stress and burnout than patients who achieved a PASI improvement of ≥75. CONCLUSION: Chronic stress and burnout have appreciable influence on HRQoL and may adversely affect treatment success in psoriasis patients. Our data underscore the importance of a multidimensional approach in the management of psoriasis.

[On the interdisciplinary S3 guidelines for the treatment of chronic idiopathic tinnitus]. / Zur interdisziplinären S3-Leitlinie für die Therapie des chronisch-idiopathischen Tinnitus.

INTRODUCTION: Tinnitus is a frequent symptom, which, particularly in combination with comorbidities, can result in a severe disease-related burden. Chronic idiopathic tinnitus (CIT) is the most frequent type of tinnitus. A considerable number of treatment strategies are used to treat CIT-for many of which there is no evidence of efficacy. In order to enable scientific evidence-based treatment of CIT, German interdisciplinary S3 guidelines have recently been constructed for the first time. Here we present a short form of these S3 guidelines. MATERIALS AND METHODS: The guidelines were constructed based on a meta-analysis of the treatment of chronic tinnitus performed by the authors. Additionally, a systematic literature search was performed in the PubMed and Cochrane Library databases. Furthermore, a systematic search for international guidelines was performed in Google, as well as in the Guidelines International Network and National Guideline Clearinghouse (USA) database. Evidence was classified according to the Oxford Centre for Evidence-Based Medicine system. RESULTS: According to the guidelines, alongside counselling, manualized structured tinnitus-specific cognitive behavioral therapy (tCBT) with a validated treatment manual is available as evidence-based therapy. In addition, the guidelines recommend concurrent treatment of comorbidities, including drug-based treatment, where appropriate. Particularly important is treatment of anxiety and depression. Where a psychic or psychiatric comorbidity is suspected, further diagnosis and treatment should be performed by an appropriately qualified specialist (psychiatrist, neurologist, psychosomatic medicine consultant) or psychological psychotherapist. In cases accompanied by deafness or hearing loss bordering on deafness, cochlear implants may be indicated. CONCLUSION: No recommendations can be made for drug-based treatment of CIT, audiotherapy, transcranial magnetic or electrical stimulation, specific forms of acoustic stimulation or music therapy; or such recommendations must remain open due to the lack of available evidence. Polypragmatic tinnitus treatment with therapeutic strategies for which there is no evidence of efficacy from controlled studies is to be refused.

520-d Isolation and confinement simulating a flight to Mars reveals heightened immune responses and alterations of leukocyte phenotype.

During interplanetary exploration, chronic stress caused by long term isolation and confinement in the spacecraft is one of the major concerns of physical and psychological health of space travelers. And for human on Earth, more and more people live in an isolated condition, which has become a common social problem in modern western society. Collective evidences have indicated prolonged chronic stress could bring big influence to human immune function, which may lead to a variety of health problems. However, to what extent long-term isolation can affect the immune system still remains largely unknow. A simulated 520-d Mars mission provided an extraordinary chance to study the effect of prolonged isolation. Six healthy males participated in this mission and their active neuroendocrine and immune conditions were studied with saliva and blood samples from all participants on chosen time points during the isolation period. As a typical neuroendocrine parameter, stress hormone cortisol was measured in the morning saliva samples. Immune phenotype changes were monitored through peripheral leukocyte phenotype analysis. Using an ex vivo viral infection simulation assay we assessed the immune response changes characterized by the ability to produce representative endogenous pro-inflammatory cytokines. The results of this study revealed elevated cortisol levels, increased lymphocyte amount and heightened immune responses, suggesting that prolonged isolation acting as chronic stressors are able to trigger leukocyte phenotype changes and poorly controlled immune responses.

Disclosure behaviour and experienced reactions in patients with HIV versus chronic viral hepatitis or diabetes mellitus in Germany.

Disclosure is a prerequisite to receive disease-specific social support. However, in the case of a stigmatised disease, it can also lead to discrimination. We aimed to assess disclosure rates of HIV patients and the reactions they encountered in comparison to patients with chronic viral hepatitis or diabetes mellitus and patients' general perception of disease-specific discrimination. We constructed a self-report questionnaire, anonymously assessing the size of the social environment, the persons who had been informed, and the experienced reactions as perceived by the disclosing patients, to be rated on 1-4 point Likert scales. In addition, patients were asked whether they perceive general discrimination in Germany. One hundred and seventy-one patients were asked to participate. Five rejected, thus questionnaires from 83 patients with HIV, 42 patients with chronic viral hepatitis B (n = 9) or C (n = 33), and 41 patients with insulin-dependent diabetes mellitus (type I n = 14, type II n = 27) were analysed. Whereas the size of the social environment did not differ, HIV-infected patients were least likely to disclose their disease (60.7%, SD ± 31.9) to their social environment as compared to patients with chronic viral hepatitis (84.2 ± 23.3%, p<0.0001), or diabetes mellitus (94.4 ± 10.3%, p<0.0001), respectively. Within the HIV patient group, the mean disclosure rate was highest to partners (90.9%), followed by the public environment (65.2%), friends (59.4%) and family members (43.8%). HIV patients experienced supportive reactions after 79.3 ± 26.4% of disclosures, which was the case in 91.4 ± 19.6% and 75.7 ± 36.1% of patients with hepatitis or diabetes mellitus, respectively. 69.5% of HIV patients stated to perceive general discrimination in Germany. We conclude that HIV patients had experienced supportive reactions after the majority of disclosures, but the low rate points out that their information strategy had been very selective. Societal discrimination of HIV patients is still an issue and needs to be further addressed.

Perceived relationships between severity of psoriasis symptoms, gender, stigmatization and quality of life.

BACKGROUND: Psoriasis is a skin disease with negative physical, psychological and social repercussions for those affected, but we still lack knowledge of how somatic and non-somatic factors directly and indirectly combine to affect patients' quality of life (QoL). OBJECTIVES: This study seeks a better understanding of the relations between symptom severity, discomfort, stigmatization, gender and QoL among psoriasis patients. METHODS: The sample comprised 381 psoriasis patients in inpatient care. Symptom severity and discomfort were measured subjectively with single items. Stigmatization was measured with the Questionnaire on Experience with Skin Complaints. QoL was measured using the Dermatology Life Quality Index (DLQI) and the Short Form-8 Health Survey (SF-8). RESULTS: Symptom severity was associated with higher discomfort, stigmatization and lower skin-related QoL. Symptom severity correlated weakly with more general aspects of QoL as measured by the SF-8. Men and women reported different experiences with discomfort, stigmatization and mental aspects of QoL (SF-8 mental component summary score). Some stigmatization parameters function as mediating variables between symptom severity and QoL. CONCLUSIONS: Our findings suggest that the effect of stigmatization on skin-related QoL is driven by symptom severity and stigmatization combined, whereas its effect on mental health is driven mostly by stigmatization alone. Further, although women and men experience the social impact of psoriasis differently, the effect of stigmatization on QoL is similar for both genders.

[Development and validation of an inventory of ego functions and self regulation (Hannover Self-Regulation Inventory, HSRI)]. / Entwicklung und Validierung eines Fragebogens zu Ich-Funktionen und zur Selbstregulationsfähigkeit (Hannover-Selbstregulations-Inventar, HSRI).

OBJECTIVE: The aim of this study was to construct and validate a short self-rating questionnaire for the assessment of ego functions and ability of self regulation. MATERIAL AND METHODS: An item pool of 120 items covering 6 postulated dimensions was reduced by two steps in independent samples (n = 136 + 470) via factor and item analyses to the final version consisting of 35 items. RESULTS: The 5 resulting questionnaire scales "interpersonal disturbances", "frustration tolerance and impulse control", "identity disturbances", "affect differentiation and affect tolerance" and "self-esteem" were well interpretable and showed in confirmatory factor analysis the best fit to the data (CHI²/df = 3.48; RMSEA = 0.73). Total scores were found to differentiate well between diagnostic groups of patients with more or less ego pathology (FANOVA = 9.8; df = 11; p < 0.001), thus proving good concurrent validity. Reliability was shown by testing internal consistency and test-retest correlations. CONCLUSION: The "Hannover self-regulation questionnaire" (HSRQ) evidently is an appropriate and reliable screening instrument in order to assess ego functions and capacities of self regulation in an economic and user-friendly means. The scale structure allows differentiated diagnostics of weak vs. stable ego functions and may be used for detailed therapy planning.

Breast lesion sizing by B-mode imaging and sonoelastography in comparison to histopathological sizing--a prospective study.

PURPOSE: This prospective study evaluates whether sonoelastography can improve B-mode ultrasonographic sizing of breast tumors. Precise measuring is important for effective therapy planning for breast cancer patients. MATERIALS AND METHODS: The size of 100 surgically excised breast lesions (92 patients: 77 malignant, 23 benign) was compared to preoperative measurements. Lesions were imaged with both ultrasonographic techniques in identical planes. The largest sizes measured with each modality were compared to the largest histopathological measurements. The interobserver variability was also computed from measurements made by two examiners assessing identical planes. RESULTS: Both ultrasonographic measuring techniques underestimate lesion size. The sonoelastography measurements were within ± 5 mm of the histological size in 70.1 % of malignant lesions, and the B-mode measurements in 57.1 % of cases. Sonoelastography leads to more accurate measurements of 13.0 % of cases (statistically not significant). A total of 22 lesions were also imaged by a second examiner. Sonoelastography had 27.3 % less interobserver variability (examiners agreed in 36.4 % of sonoelastography and in 9.1 % of B-mode results). CONCLUSION: In this study there is no significant advantage of sonoelastography, although a tendency is apparent. The low interobserver variability also favors sonoelastography for preoperative diagnostics, since it may be less dependent on the observer than conventional B-mode imaging. The results of this prospective study require validation in a prospective multicenter study with larger case numbers.

Quality management in the prophylaxis of venous thrombembolism--results of a survey including 464 medical and surgical patients.

BACKGROUND: We surveyed the quality of risk stratification politics and monitored the rate of entries to our company-wide protocol for venous thrombembolism (VTE) prophylaxis in order to identify safety concerns. PATIENTS AND METHODS: Audit in 464 medical and surgical patients to evaluate quality of VTE prophylaxis. RESULTS: Patients were classified as low 146 (31 %), medium 101 (22 %), and high risk cases 217 (47 %). Of these 262 (56.5 %) were treated according to their risk status and in accordance with our protocol, while 9 more patients were treated according to their risk status but off-protocol. Overtreatment was identified in 73 (15.7 %), undertreatment in 120 (25,9 %) of all patients. The rate of incorrect prophylaxis was significantly different between the risk categories, with more patients of the high-risk group receiving inadequate medical prophylaxis (data not shown; p = 0.038). Renal function was analyzed in 392 (84.5 %) patients. In those patients with known renal function 26 (6.6 %) received improper medical prophylaxis. If cases were added in whom prophylaxis was started without previous creatinine control, renal function was not correctly taken into account in 49 (10.6 %) of all patients. Moreover, deterioration of renal function was not excluded within one week in 78 patients (16.8 %) and blood count was not re-checked in 45 (9.7 %) of all patients after one week. There were more overtreatments in surgical (n = 53/278) and more undertreatments in medical patients (n = 54/186) (p = 0.04). Surgeons neglected renal function and blood controls significantly more often than medical doctors (p-values for both < 0.05). CONCLUSIONS: We found a low adherence with our protocol and substantial over- and undertreatment in VTE prophylaxis. Besides, we identified disregarding of renal function and safety laboratory examinations as additional safety concerns. To identify safety problems associated with medical VTE prophylaxis and "hot spots" quality management-audits proved to be valuable instruments.

Prognostic relevance of the HER2 status of circulating tumor cells in metastatic breast cancer patients screened for participation in the DETECT study program.

BACKGROUND: Circulating tumor cells (CTCs) have been reported to predict clinical outcome in metastatic breast cancer (MBC). Biology of CTCs may differ from that of the primary tumor and HER2-positive CTCs are found in some patients with HER2-negative tumors. PATIENTS AND METHODS: Patients with HER2-negative MBC were screened for participation in DETECT III and IV trials before the initiation of a new line of therapy. Blood samples were analyzed using CELLSEARCH. CTCs were labeled with an anti-HER2 antibody and classified according to staining intensity (negative, weak, moderate, or strong staining). RESULTS: Screening blood samples were analyzed in 1933 patients with HER2-negative MBC. As many as 1217 out of the 1933 screened patients (63.0%) had ≥1 CTC per 7.5 ml blood; ≥5 CTCs were detected in 735 patients (38.0%; range 1-35 078 CTCs, median 8 CTCs). HER2 status of CTCs was assessed in 1159 CTC-positive patients; ≥1 CTC with strong HER2 staining was found in 174 (15.0%) patients. The proportion of CTCs with strong HER2 staining among all CTCs of an individual patient ranged between 0.06% and 100% (mean 15.8%). Patients with estrogen receptor (ER)- and progesterone receptor (PR)-positive tumors were more likely to harbor ≥1 CTC with strong HER2 staining. CTC status was significantly associated with overall survival (OS). Detection of ≥1 CTC with strong HER2 staining was associated with shorter OS [9.7 (7.1-12.3) versus 16.5 (14.9-18.1) months in patients with CTCs with negative-to-moderate HER2 staining only, P = 0.013]. In multivariate analysis, age, ER status, PR status, Eastern Cooperative Oncology Group performance status, therapy line, and CTC status independently predicted OS. CONCLUSION: CTC detection in patients with HER2-negative disease is a strong prognostic factor. Presence of ≥1 CTC with strong HER2 staining was associated with shorter OS, supporting a biological role of HER2 expression on CTCs.

Single nucleotide polymorphisms in matrix metalloproteinase genes and lung cancer chemotherapy response and prognosis.

The prognosis for lung cancer patients treated with chemotherapy is poor. Single nucleotide polymorphisms (SNPs) in matrix metalloproteinase (MMP) genes could influence treatment outcome by altering apoptotic pathways. Eight SNPs with known or suspected phenotypic effect in six genes (MMP1, MMP2, MMP3, MMP7, MMP9 and MMP12) were investigated. For 349 Caucasian patients with primary lung cancer, receiving first-line chemotherapy, three different endpoints were analysed: response after the second cycle, progression free survival (PFS) and overall survival (OS). The prognostic value of the SNPs was analysed using multiple logistic regression for all patients and histology-, stage- and treatment-specific subgroups. Hazard ratio estimates for PFS and OS were calculated using Cox regression methods. None of the investigated polymorphisms modified response significantly in the whole patient population. However, tumour stage IIIB variant allele carriers of MMP2 C-735T showed a significantly worse response. PFS was significantly prolonged in MMP1 G-1607GG variant allele carriers and OS in small cell lung cancer patients carrying the MMP12 A-82G variant allele. In conclusion, this study identified SNPs in MMP1, MMP2, MMP7 and MMP12 for further investigation as possible predictors of chemotherapy outcome in lung cancer patients.

Measurements of chlorhexidine, p-chloroaniline, and p-chloronitrobenzene in saliva after mouth wash before and after operation with 0.2% chlorhexidine digluconate in maxillofacial surgery: a randomised controlled trial.

Chlorhexidine gluconate is used to prevent the accumulation of dental plaque and gingivitis, infection of the surgical site, and ventilator-associated pneumonia in maxillofacial surgery, but it is not clear whether the metabolites of chlorhexidine are detectable in the patient's saliva at clinically relevant concentrations. Forty-three patients who had orofacial operations were randomised to use a 0.2% chlorhexidine gluconate (n=23), or an octenidine-based, chlorhexidine-free (n=20), mouthwash once preoperatively and three times daily for five postoperative days. After the first, 8.7 (23.3) mg/L chlorhexidine (0.7%-2.5% of the total amount used) was measured in saliva. The concentration increased to 15.2 (6.2) mg/L after the second rinse (first postoperative day), and peaked at 29.4 (11.2) mg/L on the fourth postoperative day. It remained detectable for up to 12hours after the last one, but was not detectable in serum or urine at any time. The potentially carcinogenic metabolite p-chloroaniline was detectable in saliva at higher concentrations in the chlorhexidine group (0.55mg/L) than the octenidine group (0.21mg/L), and p-chloronitrobenzene was detected in both groups in only minimal concentrations (0.001-0.21mg/L). Chlorhexidine gluconate mouthwashes do increase the concentration of p-chloroaniline, but a single use seems to be safe. Whether prolonged exposure over many years may have carcinogenic potential is still not clear. Based on the hitherto unknown kinetics of p-chloroaniline in saliva, the recent recommendation of the Federal Drug Administration (FDA) in the USA to limit the use of a chlorhexidine gluconate mouthwash to a maximum of six months seems to be justified.