Photosensitisation and green egg yolks in laying hens caused by the feeding of ensiled alfalfa leaves.

1. The present study was carried out to determine the effects of feeding ensiled alfalfa leaves (ALS) as an alternative protein source to laying hens under the terms of an organic diet. Due to the occurrence of unexpected negative health effects and undesirable egg yolk pigmentation in the test groups the trial was prematurely stopped and further analysis was conducted to evaluate the responsible substances.2. Body weights of the test groups decreased significantly already in week 2 of the trial. Performance variables dropped. Olive green pigmented egg yolks were found in groups fed diets containing ALS. Severe comb necrosis occurred in the experimental group receiving the highest level of ALS (20%) combined with the option of free-range access and therefore natural light exposure.3. The noxious agent found in ALS, blood serum and egg yolk was the photosensitising chlorophyll derivate pheophorbid a (PPBa), deriving from a strong depletion of chlorophyll contained in the alfalfa leaves. PPBa caused the olive-green pigmentation found in yolks and led to photosensitivity in groups with the highest level of ALS in the diet in combination with light exposure.4. By aiming for high protein and amino acid levels, harvesting and processing have, unintentionally and initially unnoticed, led to a strong accumulation of phototoxic PPBa. From these results it is strongly advised not to include ensiled alfalfa leaves as a protein source in organic laying hen diets.

Tooth agenesis in German orthodontic patients with non-syndromic craniofacial disorder: a retrospective evaluation of panoramic radiographs.

OBJECTIVES: The study objective was to evaluate the tooth agenesis in German orthodontic patients with non-syndromic cleft lip and/or palate and Robin sequence compared to a control group without craniofacial disorder. MATERIALS/METHODS: A total of 108 panoramic radiographs were examined using the binary system of Tooth Agenesis Code (TAC) (excluding the third molar). Patients were divided into the craniofacial disorder group 1 (n = 43) and the healthy control group 2 (n = 65). Parameters such as skeletal class malformation, sex, localization of the cleft, craniofacial disorder, and interobserver reliability were assessed. RESULTS: Permanent tooth agenesis was observed in 44% of group 1 and 14% in group 2 with a statistically significant higher prevalence (p = 0.00162 (χ2)). Fourteen different TAC patterns were observed in group 1, ten of these occurring only once in separate patients. The distribution of the TAC codes in group 2 showed nine different possibilities of TAC code patterns; seven TACs were unique. In group 1, the most frequently absent teeth were the maxillary lateral incisor of the left side (30%); in group 2, the second premolar of the lower jaw on the right side (9%). Male patients with craniofacial disorder showed a higher percentage of tooth agenesis than female. CONCLUSION: The data presented here shows a statistically significant higher prevalence of tooth agenesis in German patients with non-syndromic craniofacial disorder. CLINICAL RELEVANCE: Radiographic evaluation enables the diagnosis of tooth agenesis. Recognizing early on the higher prevalence of tooth agenesis in patients exhibiting a craniofacial disorder is an important issue when developing long-term and comprehensive interdisciplinary treatment.

Non-memory cognitive symptom development in Alzheimer's disease.

BACKGROUND AND PURPOSE: Memory is known to be the most common first symptom in Alzheimer's disease (AD). Assessing non-memory cognitive symptom development in AD is important for understanding disease progression and the potential identification of treatment-responsive subtypes. METHODS: Data from the National Alzheimer's Coordinating Center were examined. Logistic regression models were fitted evaluating the development of judgement, language, visuospatial and attention symptoms at first and second visits to Alzheimer's Disease Centers. Predictors were age and prior symptoms, adjusting for symptom length and sex. The models were then refitted assessing apolipoprotein E ε4 (APOE-ε4) effects. RESULTS: Each decade reduction in presentation age increased the odds of language, visuospatial and attention symptom development at both visits by 8%-18% (P < 0.05, all tests), and judgement symptoms at the second visit by 13% (P < 0.05). Prior symptoms were not equally predictive of symptom development. For example, having first predominant language symptoms carried the lowest risk of developing other first-visit symptoms and having memory symptoms was a stronger predictor of developing judgement than other symptoms. The APOE-ε4 gene showed little impact on symptom development when included as a predictor. CONCLUSIONS: Our findings provide support for the concept that younger-onset AD is associated with the progressive development of more non-memory symptoms beyond the first time point. Associations between symptoms were evident, which may reflect that pathology can remain isolated in a network for some time. APOE-ε4 status had little influence on cognitive symptom development which may indicate that the effect it has occurs very early in the disease course.

Coding of medically unexplained symptoms and somatoform disorders by general practitioners - an exploratory focus group study.

BACKGROUND: Medically unexplained symptoms (MUS) and somatoform disorders are common in general practices, but there is evidence that general practitioners (GPs) rarely use these codes. Assuming that correct classification and coding of symptoms and diseases are important for adequate management and treatment, insights into these processes could reveal problematic areas and possible solutions. Our study aims at exploring general practitioners' views on coding and reasons for not coding MUS/somatoform disorders. METHODS: We invited GPs to participate in six focus groups (N = 42). Patient vignettes and a semi-structured guideline were used by two moderators to facilitate the discussions. Recordings were transcribed verbatim. Two researchers analyzed the data using structuring content analysis with deductive and inductive category building. RESULTS: Three main categories turned out to be most relevant. For category a) "benefits of coding" GPs described that coding is seen as being done for reimbursement purposes and is not necessarily linked to the content of their reference files for a specific patient. Others reported to code specific diagnoses only if longer consultations to explore psychosomatic symptoms or psychotherapy are intended to be billed. Reasons for b) "restrained coding" were attempting to protect the patient from stigma through certain diagnoses and the preference for tentative diagnoses and functional coding. Some GPs admitted to c) "code inaccurately" attributing this to insufficient knowledge of ICD-10-criteria, time constraints or using "rules of thumb" for coding. CONCLUSIONS: There seem to be challenges in the process of coding of MUS and somatoform disorders, but GPs appear not to contest the patients' suffering and accept uncertainty (about diagnoses) as an elementary part of their work. From GPs' points of view ICD-10-coding does not appear to be a necessary requirement for treating patients and coding might be avoided to protect the patients from stigma and other negative consequences. Our findings supply a possible explanation for the commonly seen difference between routine and epidemiological data. The recent developments in the DSM-5 and the upcoming ICD-11 will supposedly change acceptance and handling of these diagnoses for GPs and patients. Either way, consequences for GPs' diagnosing and coding behavior are not yet foreseeable.

Electron holography on HfO2/HfO2-x bilayer structures with multilevel resistive switching properties.

Unveiling the physical nature of the oxygen-deficient conductive filaments (CFs) that are responsible for the resistive switching of the HfO2-based resistive random access memory (RRAM) devices represents a challenging task due to the oxygen vacancy related defect nature and nanometer size of the CFs. As a first important step to this goal, we demonstrate in this work direct visualization and a study of physico-chemical properties of oxygen-deficient amorphous HfO2-x by carrying out transmission electron microscopy electron holography as well as energy dispersive x-ray spectroscopy on HfO2/HfO2-x bilayer heterostructures, which are realized by reactive molecular beam epitaxy. Furthermore, compared to single layer devices, Pt/HfO2/HfO2-x /TiN bilayer devices show enhanced resistive switching characteristics with multilevel behavior, indicating their potential as electronic synapses in future neuromorphic computing applications.

Genotoxic and biochemical changes in Baccharis trimera induced by coal contamination.

The processing and combustion of coal in thermal power plants release anthropogenic chemicals into the environment. Baccharis trimera is a common plant used in folk medicine that grows readily in soils degraded by coal mining activities. This shrub bioaccumulates metals released into the environment, and thus its consumption may be harmful to health. The purpose of this study was to investigate the phytochemical profile, antioxidant capacity (DPPH), genotoxic (comet assay) and mutagenic potential (CBMN-cyt) in V79 cells of B. trimera aqueous extracts in the coal-mining region of Candiota (Bt-AEC), and in Bagé, a city that does not experience the effects of exposure to coal (Bt-AEB, a reference site). In the comet assay, only Bt-AEC was genotoxic at the highest doses (0.8mg/mL and 1.6mg/mL), compared to the control. For extracts from both areas, mutagenic effects were observed at higher concentrations compared to the control. The cell damage parameters were significantly high in both extracts; however, more striking values were observed for Bt-AEC, up to the dose of 0.8mg/mL. In chemical analysis, no variation was observed in the contents of flavonoids and phenolic compounds, neither the antioxidant activity, which may suggest that DNA damage observed in V79 cells was induced by the presence of coal contaminants absorbed by the plant.

Balloon Eustachian tuboplasty: a retrospective cohort study.

BACKGROUND: Eustachian tube dysfunction is regarded as a 'black box' term, reflecting a spectrum of dysfunction. The key to its diagnosis and management is in identifying the aetiology and exact pathophysiology of the dysfunction. DESIGN: We present our retrospective 5-year results for the technique of transnasal endoscopic balloon dilatation of the cartilaginous part of the Eustachian tube, balloon Eustachian tuboplasty (BET). The indication for treatment is chronic obstructive Eustachian tube dysfunction. MAIN OUTCOME MEASURES: Preoperatively, the Eustachian tube score (ETS) was obtained by a clinico-objective assessment involving tubomanometry (TMM) and reported patient symptom. The measurements were repeated 1, 2, 3, 4 and 5 years postoperatively. SETTING: Tertiary referral centre. PARTICIPANTS: A total of 622 patients (1076 ears) were treated with BET. RESULTS: One year after treatment, the Eustachian tube score improved from 3.13 (± 2.47 SD) to 5.75 (± 2.76 SD). The Eustachian tube score improved significantly in 73% of ears. The average Eustachian tube score 2 years after treatment improved from 2.65 (± 2.89 SD) to 6.26 (± 3.07 SD). In 82% of patients, the Eustachian tube score improved significantly at 5 years. The subjective satisfaction of the patients was approximately 80%. CONCLUSIONS: Our long-term results suggest that BET is a safe and feasible treatment for chronic obstructive Eustachian tube dysfunction with a success rate of more than 70%. This study has important implications for other Eustachian tube-related clinical entities, such as glue ear management (adults and children), continued grommet insertion and tympanomastoid surgery outcomes.

Evaluation of tubomanometry as a routine diagnostic tool for chronic obstructive Eustachian tube dysfunction.

OBJECTIVE: The objective of this study was to demonstrate the reliability of tubomanometry (TMM) described by Estéve in the diagnosis of chronic obstructive Eustachian tube (ET) dysfunction. STUDY DESIGN: Combined prospective and retrospective clinical study. SETTING: Tertiary referral centre, affiliated to university. METHODS: Two hundred and fifteen healthy subjects were examined once, 25 healthy subjects underwent TMM weekly for 6 weeks, and six healthy subjects were tested three times a day on at least three different days. The results of tubomanometry in healthy subjects were compared to data obtained from 171 patients with chronic obstructive ET dysfunction. RESULTS: In healthy subjects, there was an immediate opening of the ET at 30-50 mbar with an R-value ≤ 1 in at least 94% of the cases. In patients with chronic ET dysfunction, an opening of the ET could be registered in only 42% of patients at 30 mbar and in 58% at 50 mbar. The average of the R-value in these subjects always indicated towards a delayed opening (R > 1). When measurements are repeated in the same subject with a weekly interval, the intraclass correlation (ICC) was 0.49 for the TMM with 30 mbar, 0.51 for the TMM with 40 mbar and 0.52 for the TMM with 50 mbar in healthy people. For the patients with symptoms of ET dysfunction, the ICC for up to four repeated measures was 0.50 for the TMM with 30 mbar, 0.53 for the TMM with 40 mbar and 0.54 for the TMM with 50 mbar. A complete agreement of the results in repeated measurements within seconds was present in 86% for 30 and 40 mbar and in 79% for 50 mbar. The ICC was 0.61 for the TMM with 50 mbar, 0.62 for the TMM with 40 mbar and 0.68 for the TMM with 30 mbar. CONCLUSIONS: Tubomanometry can support the diagnosis of ET dysfunction. An R-value ≤ 1 indicates a regular function of the ET, an R-value >1 indicates a delayed opening of the ET, and no definable R-value means no detectable opening of the ET. TMM is a reliable and valid instrument to support the diagnosis of chronic obstructive ET dysfunction.

[Bacteriologic investigation of the Eustachian tube and the implications of perioperative antibiotics before balloon dilation]. / Bakteriologische Untersuchungen der Tuba auditiva und die Implikation einer perioperativen Antibiotikagabe vor Ballondilatation.

BACKGROUND: Balloon Eustachian Tuboplasty (BET) is a new minimally invasive treatment for chronic Eustachian tube dysfunction (ETD). Initially, perioperative prophylactic antibiotic therapy with ciprofloxacin 2 × 500 mg p.o. for 5 days was administered. This study aimed to characterize the bacterial flora in the ET, nose, and pharynx in patients with chronic obstructive ETD. Additionally, we investigated the necessity of perioperative antibiotic prophylaxis in BET patients. PATIENTS AND METHODS: We examined 40 patients undergoing BET: 20 patients with and 20 patients without perioperative antibiotic prophylaxis. All patients were followed-up for clinical signs and symptoms of local infection for at least 2 weeks after surgery. Following BET, the tips of 35 balloon catheters, as well as swabs from the nose and pharynx were sent for microbiologic analysis. RESULTS: None of these 40 patients had postoperative signs of infection. Of the swabs of the balloon catheters, 46% were sterile and 23% showed standard flora. The remaining 31% of swaps revealed specific bacteria. However, none of the nasal or nasopharyngeal swaps were sterile. CONCLUSION: Due to the lack of signs of postoperative infection in either investigated group, the authors no longer favor use of perioperative antibiotic prophylaxis in patients undergoing BET. The relevance of biofilms and pathogen colonization to ET function has recently been intensively discussed, and should be further investigated in future studies.

[Assessment of chronic obstructive eustachian tube dysfunction : Evaluation of the German version of the Eustachian Tube Dysfunction Questionnaire]. / Beurteilung der chronisch-obstruktiven Tubenfunktionsstörung : Evaluation des "Eustachian Tube Dysfunction Questionnaire" in der deutschen Übersetzung.

BACKGROUND: Eustachian tube dysfunction can cause middle ear diseases and impair quality of life. Sufficient diagnostic tools for chronic obstructive eustachian tube dysfunction are lacking and not reliable enough. PATIENTS AND METHODS: The Eustachian Tube Dysfunction Questionnaire (ETDQ-7) was published by McCoul et al. in 2012 as an instrument to evaluate eustachian tube function. They demonstrated the reliability und validity of their questionnaire. The cut-off point for the diagnosis of eustachian tube dysfunction is ≥ 14.5 at 100 % sensitivity and 100 % specificity. We translated the ETDQ-7 into German and used it on 100 healthy subjects and 43 patients with chronic obstructive eustachian tube dysfunction. RESULTS: The results in the English questionnaire were confirmed by our examinations with the German version of the questionnaire. The mean ETDQ-7 score was 8.67 in the healthy subjects and 24.7 in the patients with chronic obstructive eustachian tube dysfunction. The area under the curve in ROC analysis was 98.8 % (p < 0.0001). CONCLUSION: We recommend the ETDQ-7 as an addition to patient history in the examination of eustachian tube dysfunction. It may as well be valuable in follow-up examinations to monitor treatment success.

Mechanisms and rescue strategies of calcineurin inhibitor mediated tolerance abrogation induced by anti-CD4 mAb treatment.

To ensure safety tolerance induction protocols are accompanied by conventional immunosuppressive drugs (IS). But IS such as calcineurin inhibitors (CNI), for example, cyclosporin A (CsA), can interfere with tolerance induction. We investigated the effect of an additional transient CsA treatment on anti-CD4mAb-induced tolerance induction upon rat kidney transplantation. Additional CsA treatment induced deteriorated graft function, resulting in chronic rejection characterized by glomerulosclerosis, interstitial fibrosis, tubular atrophy and vascular changes. Microarray analysis revealed enhanced intragraft expression of the B cell attracting chemokine CXCL13 early during CsA treatment. Increase in CXCL13 expression is accompanied by enhanced B cell infiltration with local and systemic IgG production and C3d deposition as early as 5 days upon CsA withdrawal. Adding different CNIs to cultures of primary mesangial cells isolated from glomeruli resulted in a concentration-dependent increase in CXCL13 transcription. CsA in synergy with TNF-α can enhance the B cell attracting and activating potential of mesangial cells. Transient B cell depletion or transfer of splenocytes from tolerant recipients 3 weeks after transplantation could rescue tolerance induction and did inhibit intragraft B cell accumulation, alloantibody production and ameliorate chronic rejection.

Clocks for the city: circadian differences between forest and city songbirds.

To keep pace with progressing urbanization organisms must cope with extensive habitat change. Anthropogenic light and noise have modified differences between day and night, and may thereby interfere with circadian clocks. Urbanized species, such as birds, are known to advance their activity to early morning and night hours. We hypothesized that such modified activity patterns are reflected by properties of the endogenous circadian clock. Using automatic radio-telemetry, we tested this idea by comparing activity patterns of free-living forest and city European blackbirds (Turdus merula). We then recaptured the same individuals and recorded their activity under constant conditions. City birds started their activity earlier and had faster but less robust circadian oscillation of locomotor activity than forest conspecifics. Circadian period length predicted start of activity in the field, and this relationship was mainly explained by fast-paced and early-rising city birds. Although based on only two populations, our findings point to links between city life, chronotype and circadian phenotype in songbirds, and potentially in other organisms that colonize urban habitats, and highlight that urban environments can significantly modify biologically important rhythms in wild organisms.

Concomitant lipopolysaccharide-induced transfer of blood-derived components including immunoglobulins into milk.

During a mammary immune response, the integrity of the blood-milk barrier is negatively affected and becomes leaky. The aim of the present study was to demonstrate the blood origin, and to investigate changes in the concentration, of various constituents including immunoglobulins in blood and milk during the early phase of lipopolysaccharide (LPS)-induced mastitis. Five lactating dairy cows received continuous ß-hydroxybutyrate (BHBA) clamp infusions to maintain elevated BHBA blood concentrations (1.5 to 2.0 mmol/L) from 48 h before and 8h after LPS administration. One udder quarter was infused with 200 µg of Escherichia coli LPS. A second quarter served as control. Milk and blood samples were taken hourly for 8h postchallenge (PC). The somatic cell count in LPS-challenged quarters was increased from 4h PC to the end of the experiment compared with control quarters. In LPS-challenged quarters, l-lactate, BHBA, lactate dehydrogenase (LDH), IgG(1), and IgG(2) were increased at 3h PC and remained elevated until the end of experiment (8h PC) compared with control quarters. In addition, the optical density values in milk in a nonquantitative ELISA for antibodies directed against bluetongue virus (used as a measure of nonspecific antibody transfer; all animals were vaccinated) increased and, thus, indicates an increase in these antibodies in response to LPS treatment. l-Lactate concentration also increased in blood 2h PC and in the milk of control quarters during the experiment from 3h PC. A second experiment was conducted in vitro to investigate a possible contribution from destructed milk cells to l-lactate concentration and activity of LDH in milk. Aliquots of milk samples (n=8) were frozen (-20°C) or disrupted with ultrasound, respectively. Freeze thawing and ultrasound treatment increased LDH in milk samples, but had no effect on l-lactate concentrations. Results suggest that intramammary infusion of LPS induces a systemic response, as evidenced by an elevation of blood l-lactate concentration. The concomitant changes of all investigated components suggest that they were blood derived. However, the increase in blood components in the milk is not necessarily supportive of the mammary immune system, and likely a side effect of reduced blood-milk barrier integrity.

Short communication: differential immunoglobulin transfer during mastitis challenge by pathogen-specific components.

Mastitis induced by Escherichia coli is often characterized by severe clinical signs, indicating a more powerful combat of the immune system against the pathogen compared with Staphylococcus aureus infections, which are often represented by chronic and subclinical diseases. The aim of this study was to test the major pathogenic component lipopolysaccharide (LPS) from E. coli and lipoteichoic acid (LTA) from Staph. aureus for their effects on blood-milk barrier integrity and the related transfer of immunoglobulins and lactate from blood into milk. A similar somatic cell count (SCC) increase was achieved by intramammary challenge of 1 quarter of 5 cows with 20 µg of LTA, and 8 cows with 0.2 µg of LPS (maximum log SCC/mL: 7). Milk IgG(1) concentrations increased in LPS- but not in LTA-challenged quarters. Milk IgG(2) concentrations were increased in treated quarters at 3h after LPS, and 6h after LTA challenge. Higher maximum levels of IgG(2) were reached in milk of LPS-treated quarters (173 ± 58 µg/mL) than of LTA-challenged quarters (62 ± 13 µg/mL). Immunoglobulin G(1) and IgG(2) levels did not change in control quarters. l-Lactate concentrations in milk increased 4h after LPS and 5h after LTA challenge and reached higher maximum levels in LPS- (221 ± 48 mg/L) than in LTA-treated quarters (77 ± 18 mg/L). In conclusion, a mammary inflammation on a quantitatively similar level based on SCC increase achieves a more efficient transfer of blood components such as IgG(2) via the blood-milk barrier if induced by LPS from E. coli than by LTA from Staph. aureus. This pathogen-specific difference may play an important role in the cure rate of the respective intramammary infection, which is usually lower in Staph. aureus- than in E. coli-induced mastitis.

[Validation and first results of the German QUOTE-IBD to measure quality of care from the perspective of patients with inflammatory bowel disease]. / Validierung und erste Ergebnisse des deutschen QUOTE-IBD zur Erfassung der Behandlungsqualität aus Sicht der Patienten mit chronisch-entzündlichen Darmerkrankungen.

INTRODUCTION: The quality of care is especially relevant to patients with inflammatory bowel disease (IBD) and may be used in the context of quality management and for evaluation of interventions in health services research. To the best of our knowledge no German disease-specific and validated tool exists to measure the quality of the care that IBD patients receive. METHODS: QUOTE-IBD is a validated questionnaire to assess the disease-specific quality of care from an IBD patient's perspective. It was translated into German and validated after being answered by 100 patients of our IBD outpatient clinic. To assess convergent validity a visual analogue scale and the Qualiskope-A questionnaire measuring patient satisfaction regardless of disease was used. Furthermore, we evaluated quality of care in the patient collective analysed for validation. RESULTS: The German QUOTE-IBD questionaire was very well accepted by patients and showed reliability in measuring overall satisfaction. Good correlations between overall satisfaction and the visual analogue scale as well as patient satisfaction measured by the Qualiskope A could be demonstrated. The mean overall satisfaction among the analysed patient collective was very high. Statements on importance or deficits in specific areas of care can hardly be given because of insufficient reliability and validity at the scale level. DISCUSSION: With the German QUOTE-IBD questionaire there is now a reliable and valid instrument available for measuring quality of care and satisfaction from the perspective of patients with chronic inflammatory bowel disease.

[Impact of implementation strategies on adherence rates to colorectal cancer (CRC) guidelines after polypectomy in a university hospital]. / Einfluss von Weiterbildungsmaßnahmen auf die leitliniengerechten Nachsorgeempfehlungen nach Polypektomie aus dem Dickdarm in einem Universitätsklinikum.

BACKGROUND: Colorectal cancer (CRC) is the second most common malignancy in Germany. Screening colonoscopies with polypectomy have been demonstrated to reduce the incidence of CRC. Detailed recommendations on scheduling screening and follow-up colonoscopies have therefore been included into national guidelines. Knowledge about CRC guidelines and adherence to guideline recommendations varies greatly among physicians. METHODS: We combined different implementation strategies (training courses, case discussion, handouts, wall charts) to improve adherence of recommendations for scheduling follow-up colonoscopy. To assess adherence, written recommendations given at discharge after inpatient treatment for polypectomy were analysed before (n = 111) and after (n = 83) the implementation of the above-mentioned implementation measures. Additional factors possibly influencing the recommendations of physicians were collected (histology, polyp size). RESULTS: The adherence to the CRC guideline before implementation of the above-mentioned measures was moderate. After intervention, there was a non-significant increase from 47 % to 53 %. Senior physician review and editing of the discharge summaries improved guideline adherence of recommendations to 69 %. Neither the education level of residents nor their affiliation to a certain department had an impact on the quality of the recommendations. Histology and in particular information on the resection status of the polyps in the pathology report (complete versus incomplete resection) had an influence of the recommended schedule. Furthermore, size of the polyps, but not the number, had a statistically significant influence on the quality of the recommendations. CONCLUSIONS: The inadequate improvement of guideline adherence can possibly be explained by the insufficient interactive and repetitive character of interventions. As the histology reports seem to have an influence on the recommendations in regards to the interval to the next colonoscopy, interdisciplinary teaching is necessary to improve guideline concurrent care.

Mutations in the hminK gene cause long QT syndrome and suppress IKs function.

Ion-channel beta-subunits are ancillary proteins that co-assemble with alpha-subunits to modulate the gating kinetics and enhance stability of multimeric channel complexes. Despite their functional importance, dysfunction of potassium-channel beta-subunits has not been associated with disease. Recent physiological studies suggest that KCNE1 encodes beta-subunits (hminK) that co-assemble with KvLQT1 alpha-subunits to form the slowly activating delayed rectifier K+ (IKs) channel. Because KVLQT1 mutations cause arrhythmia susceptibility in the long QT syndrome (LQT), we hypothesized that mutations in KCNE1 also cause this disorder. Here, we define KCNE1 missense mutations in affected members of two LQT families. Both mutations (S74L, D76N) reduced IKs by shifting the voltage dependence of activation and accelerating channel deactivation. D76N hminK also had a strong dominant-negative effect. The functional consequences of these mutations would be delayed cardiac repolarization and an increased risk of arrhythmia. This is the first description of KCNE1 as an LQT gene and confirms that hminK is an integral protein of the IKs channel.

Two long QT syndrome loci map to chromosomes 3 and 7 with evidence for further heterogeneity.

Cardiac arrhythmias cause sudden death in 300,000 United States citizens every year. In this study, we describe two new loci for an inherited cardiac arrhythmia, long QT syndrome (LQT). In 1991 we reported linkage of LQT to chromosome 11p15.5. In this study we demonstrate further linkage to D7S483 in nine families with a combined lod score of 19.41 and to D3S1100 in three families with a combined score of 6.72. These findings localize major LQT genes to chromosomes 7q35-36 and 3p21-24, respectively. Linkage to any known locus was excluded in three families indicating that additional heterogeneity exists. Proteins encoded by different LQT genes may interact to modulate cardiac repolarization and arrhythmia risk.