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1.
Gesundheitswesen ; 75(8-9): e108-12, 2013 Aug.
Article in German | MEDLINE | ID: mdl-23175164

ABSTRACT

AIM: The introduction of quality management systems might be promoted by use of recognised certification programmes. Over the years, in health care organisations the certification model named KTQ has gained more and more importance. The aim of this study is to evaluate intra-organisational effects in a clinic after introduction of quality management on the basis of KTQ. METHODS: The evaluation was performed using a 2-step approach: first, before starting the implementation process of KTQ in the year 2008, and second, after the implementation process had become successful. Data were obtained by a systematic questionnaire survey. Hospital staff (physicians, nurses, and others like administration staff, technical and medical assistants) were asked to appraise the quality management, to give own preferences, and rate their overall satisfaction with the process. RESULTS: Response rates were 56% in the year 2008 and 50% in the year 2010. Subjects regarding the working atmosphere, leading of superiors, organisational issues, and pervasion of quality management predominantly were found to be improved, almost with high statistical significance. At the same time, higher satisfaction values could be determined. CONCLUSIONS: There might be high acceptance to the undergone changes from the staff members' point of view. It appears that the implementation process has led to higher satisfaction values. Moreover it can be concluded that certification programmes might be able to promote the needed pervasion of quality management throughout the institution.


Subject(s)
Attitude of Health Personnel , Certification/organization & administration , Efficiency, Organizational/statistics & numerical data , Hospital Administration/standards , Quality Assurance, Health Care/statistics & numerical data , Quality Assurance, Health Care/standards , Total Quality Management/standards , Efficiency, Organizational/standards , Germany , Hospital Administration/statistics & numerical data , Interdepartmental Relations , Surveys and Questionnaires , Total Quality Management/statistics & numerical data
2.
J Eur Acad Dermatol Venereol ; 26(1): 71-8, 2012 Jan.
Article in English | MEDLINE | ID: mdl-22168776

ABSTRACT

OBJECTIVE: The aim of this study was to evaluate the safety and efficacy profile of pegylated interferon α-2b (PEG-IFN α-2b) in combination with photochemotherapy (PUVA) in the treatment of cutaneous T-cell lymphoma (CTCL) in comparison with standard IFN α plus PUVA. DESIGN: Retrospective cohort study over a period of 7 years. PATIENTS AND INTERVENTIONS: A total of 17 consecutive CTCL patients (stage IA-IV) were retrospectively analysed for toxicity and response rates associated with PEG-IFN α-2b (1.5 µg/kg weekly) plus PUVA (n = 9) or standard IFN α-2a (9 MIU 3×/week) plus PUVA (n = 8). MAIN OUTCOME MEASURES: Differences of response rates (complete/partial remission), progression-free survival, discontinuation of therapy, safety and toxicity profiles according to World Health Organization - Common Terminology Criteria of Adverse Events (WHO-CTCAE). RESULTS: Myelosuppression and liver toxicity occured more frequently during PEG-IFN α-2b plus PUVA treatment than during standard IFN α-2a plus PUVA therapy [77.8 vs. 50% (odds ratio 1.477) and 77.8 vs. 50% (odds ratio 1.692), respectively]. By contrast, the occurence of constitutional side-effects (mainly fatigue) [100 vs.77.8% (odds ratio 0.889)] and more adverse events leading to study discontinuation was considerably higher in the standard IFN α-2a plus PUVA group. The overall response rate in the PEG-IFN α-2b plus PUVA group (89%) was significantly superior. CONCLUSIONS: In patients with cutaneous T-cell lymphoma PEG-IFN α-2b plus PUVA might become a promising treatment alternative as its higher rate of myelosuppression and liver toxicity is outweighed by its lower percentage of constitutional side-effects, and its significantly higher overall response. Due to the small number of participants at this retrospective study, a larger prospective study is essential to verify our results.


Subject(s)
Ficusin/therapeutic use , Interferon-alpha/therapeutic use , Lymphoma, T-Cell/drug therapy , PUVA Therapy , Photosensitizing Agents/therapeutic use , Polyethylene Glycols/therapeutic use , Skin Neoplasms/drug therapy , Adult , Aged , Female , Ficusin/administration & dosage , Ficusin/adverse effects , Humans , Interferon alpha-2 , Interferon-alpha/administration & dosage , Interferon-alpha/adverse effects , Male , Middle Aged , Photosensitizing Agents/administration & dosage , Photosensitizing Agents/adverse effects , Polyethylene Glycols/administration & dosage , Polyethylene Glycols/adverse effects , Recombinant Proteins/administration & dosage , Recombinant Proteins/adverse effects , Recombinant Proteins/therapeutic use , Retrospective Studies
3.
Gesundheitswesen ; 71(7): 405-13, 2009 Jul.
Article in German | MEDLINE | ID: mdl-19387930

ABSTRACT

OBJECTIVE: This survey aims to identify psychosocial issues in the outpatient care of acne vulgaris in dermatological and paediatric practices. The main object of the study lies on the impact of psychosocial stresses and strains, and offers of support in medical care. METHOD: Questionnaires were sent out to all dermatologists and paediatricians in private practice in Westphalia-Lippe (n=678) using a combined quantitative and qualitative approach. The average response rate was 41.0% (n=278), for paediatrics 43.7% (n=190) and dermatology 36.3% (n=88), respectively. Methods of descriptive statistics were applied. Qualitative data were analysed using a qualitative content analysis. RESULTS: From the physicians' point of view several needs of psychosocial care are seen, however, predominantly focussing on psychotherapeutic and inpatient medical care. Correspondingly, patients' demands for psychosocial care were also indicated. The responding physicians were not aware of low threshold offers of support such as self-help, support and advocacy organisations, social services or help-desks. These offers do not play an important role in outpatient care. Altogether only a minor group of respondents cooperates with these named institutions providing psychosocial care services. CONCLUSIONS: The integration of psychosocial care is not common practice in the outpatient care of acne vulgaris. On the one hand physicians are willing to cooperate with caring institutions inside and outside the health care system; on the other hand cooperation is limited by lots of structural and fiscal barriers. The mental and psychological stresses related to acne vulgaris are evident and important for social and emotional development of children and adolescents. Although this fact is actually being perceived, the implementation of psychosocial issues is medical practice remains inadequate.


Subject(s)
Acne Vulgaris/epidemiology , Acne Vulgaris/psychology , Ambulatory Care/psychology , Attitude of Health Personnel , Physicians/statistics & numerical data , Stress, Psychological/epidemiology , Stress, Psychological/psychology , Comorbidity , Data Collection , Female , Germany/epidemiology , Humans , Male , Psychology , Risk Assessment , Risk Factors
4.
Eur J Public Health ; 18(1): 85-91, 2008 Feb.
Article in English | MEDLINE | ID: mdl-17569699

ABSTRACT

BACKGROUND: German diagnosis-related groups (G-DRG) have been introduced in Germany as a reimbursement system for in-patient care. The aim of this study was to report data-based experiences from the introduction process and to evaluate the impact on in-patient dermatology. METHODS: A quantitative analysis including clinical data from two large university centres of dermatology over a time period of 4 years (2003-06) has been performed. Characteristics and trends of case-mix index, number of cases, average age, length of stay (LOS), surgical and medical treatments and in-patient case groups were studied in detail. RESULTS: It was found that the case-mix index values increased after the introduction period, but subsequently declined on the initial value. At the same time, an increase of dermatological hospital admissions can be noticed parallel to a significant reduction of LOS (P < 0.001) and a moderate increase of average age (P < 0.001). Analysis of DRG assignment revealed an initial significant decline of surgical in-patient procedures and increasing medical treatments, however, without obvious long-term changes. Furthermore, a growing importance for dermatological oncology and inflammable skin diseases within the in-patient setting could be observed. CONCLUSIONS: The introduction of the G-DRG system in Germany induced changes in in-patient care affecting hospital admission rates, LOS and cases treated in an in-patient setting. In-patient activities have not been reduced with the DRG introduction; however, long-term interdisciplinary research approaches are needed to explore the future impact on health care providing and quality of health care in depth.


Subject(s)
Dermatology/economics , Diagnosis-Related Groups/economics , Skin Diseases/therapy , Dermatology/methods , Diagnosis-Related Groups/statistics & numerical data , Germany/epidemiology , Health Policy/economics , Health Policy/trends , Hospitals, University/economics , Humans , Inpatients , Insurance, Health, Reimbursement/economics , Length of Stay , Risk Adjustment , Skin Diseases/economics , Skin Diseases/epidemiology
5.
Urologe A ; 44(12): 1463-8, 2005 Dec.
Article in German | MEDLINE | ID: mdl-16133229

ABSTRACT

INTRODUCTION AND OBJECTIVE: In order to support the introduction of quality management, a systematic patient questionnaire was used in the Urology Clinic of the University Hospital of Münster and in another comparable clinic. The aim was to distinguish between well established areas and areas needing improvement. METHODS: A multidimensional questionnaire with emphasis on items involving patient satisfaction was developed and handed out to the patients before they left the clinic. The questionnaire could be sent back with an enclosed envelop free of charge. RESULTS: Hospital hygiene was rated as most important factor by the patients, followed by professionalism of the physicians and nurses. Patients were dissatisfied with hospital hygiene, making this an issue for improvement. Physicians and nurses were rated positively in both clinics. Furthermore, a high proportion of patients (82%) said that they had no pain after surgery. Overall, patients were very satisfied with their hospital stay in both clinics. CONCLUSIONS: After analyzing the questionnaires, we could identify areas in need of improvement and areas of high performance. In particular, hospital hygiene needs to be improved. In order to reach more patients, the inquiries need to be performed in all departments of the University Hospital of Münster.


Subject(s)
Academic Medical Centers/statistics & numerical data , Attitude to Health , Hospitalization/statistics & numerical data , Patient Satisfaction/statistics & numerical data , Quality Assurance, Health Care/methods , Surveys and Questionnaires , Urology Department, Hospital/statistics & numerical data , Germany , Humans , Pilot Projects
6.
J Eur Acad Dermatol Venereol ; 19(5): 582-8, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16164713

ABSTRACT

OBJECTIVE: The changing healthcare environment world-wide is leading to extensive use of per case payment systems based on diagnosis-related groups (DRG). The aim of this study was to examine the impact of application of different DRG systems used in the German healthcare system. METHODS: We retrospectively analysed 2334 clinical data sets of inpatients discharged from an academic dermatological inpatient unit in 2003. Data were regarded as providing high coding quality in compliance with the diagnosis and procedure classifications as well as coding standards. The application of the Australian AR-DRG version 4.1, the German G-DRG version 1.0, and the German G-DRG version 2004 was considered in detail. To evaluate more specific aspects, data were broken down into 11 groups based on the principle diagnosis. MAIN OUTCOME MEASURE: DRG cost weights and case mix index were used to compare coverage of inpatient dermatological services. Economic impacts were illustrated by case mix volumes and calculation of DRG payments. RESULTS: Case mix index results and the pending prospective revenues vary tremendously from the application of one or another of the DRG systems. The G-DRG version 2004 provides increased levels of case mix index that encourages, in particular, medical dermatology. CONCLUSIONS: The AR-DRG version 4.1 and the first German DRG version 1.0 appear to be less suitable to adequately cover inpatient dermatology. The G-DRG version 2004 has been greatly improved, probably due to proceeding calculation standards and DRG adjustments. The future of inpatient dermatology is subject to appropriate depiction of well-established treatment standards.


Subject(s)
Case Management/economics , Dermatology/economics , Diagnosis-Related Groups/economics , Hospital Costs , Dermatology/methods , Female , Forms and Records Control , Germany , Health Care Reform , Humans , Inpatients , Male , National Health Programs/organization & administration , Quality of Health Care , Retrospective Studies , Risk Assessment , Skin Diseases/diagnosis , Skin Diseases/economics , Skin Diseases/therapy
7.
J Dtsch Dermatol Ges ; 3(12): 1016-24, 2005 Dec.
Article in German | MEDLINE | ID: mdl-16405719

ABSTRACT

Recently the catalogue for ambulatory surgery in hospitals has been updated presenting a successful integration into the classification of EMB 2000plus. A fundamental reconstruction resulted in changes to the specifications of health care services which are covered by the catalogue. The agreement became effective in April 2005. According to the new catalogue for ambulatory surgery, the procedure codes of the OPS classification and their transitions to a specified EBM-figure or category are relevant for the reimbursement of ambulatory services provided by a hospital or in private practice. Moreover, the regulations to avoid unnecessary bed days of hospital care and the criteria of the German appropriateness evaluation protocol (G-AEP) have to be considered carefully in terms of inpatient admissions. In the following the revised catalogue for ambulatory surgery is reviewed in detail with special relevance to dermatology.


Subject(s)
Ambulatory Surgical Procedures/legislation & jurisprudence , Dermatology/legislation & jurisprudence , Government Regulation , Practice Guidelines as Topic , Skin Diseases/surgery , Ambulatory Surgical Procedures/standards , Dermatology/standards , Germany , Humans , Practice Patterns, Physicians'/legislation & jurisprudence
8.
Hautarzt ; 55(11): 1039-46, 2004 Nov.
Article in German | MEDLINE | ID: mdl-15375624

ABSTRACT

BACKGROUND: Since January 2004, all German hospitals have been obliged to operate with a new hospital funding system based on DRGs. For the DRG system to serve as a fair basis for reimbursement requires that the dermatologic services be adequately covered in the classification system. The German Dermatologic Society (DDG) in cooperation with the DRG-Research Group of the University Hospital Muenster carried out a DRG evaluation study. Based on these results, suggestions for the adjustment of the G-DRG system were proposed by the DDG in the G-DRG adaptation round for 2004. METHODS: Based on data of the DRG evaluation project (14,555 dermatological cases from 19 hospitals) the homogeneity in the G-DRG system 2004 was examined and compared with the quality of depiction in the G-DRG version 1.0. RESULTS: The correlation between expenditure and case mix index in the hospitals improved in the G-DRG system 2004. Most proposals submitted by the German Dermatologic Society for the adaptation into the G-DRG system 2004 were accepted. Some fundamental problems such as reimbursement of high cost drugs and special services, as well as the reimbursement of high and low outliers, were only marginally addressed. CONCLUSIONS: The G-DRG system 2004 will need to be continuously adapted in the field of dermatology. Based on this work, the German Dermatologic Society has made suggestions to be adapted in the G-DRG system 2005 and submitted them to the German DRG Institute.


Subject(s)
Cost-Benefit Analysis/methods , Dermatology/economics , Diagnosis-Related Groups/economics , Practice Patterns, Physicians'/statistics & numerical data , Quality Assurance, Health Care/methods , Skin Diseases/economics , Skin Diseases/epidemiology , Cost-Benefit Analysis/economics , Dermatology/statistics & numerical data , Germany/epidemiology , Humans , Practice Patterns, Physicians'/economics , Skin Diseases/classification , Skin Diseases/diagnosis , Skin Diseases/therapy
9.
Z Gastroenterol ; 42(8): 775-84, 2004 Aug.
Article in German | MEDLINE | ID: mdl-15314731

ABSTRACT

The German self-governing bodies have concluded an agreement about ambulant operations and procedures which replaces the inpatient health care situation. It came into force on January 1, 2004. The published catalogue contains specific treatment procedures which define more clearly some problems that occur between the provision of outpatient and inpatient services in the German health care system. Clinical physicians and practising specialists now have equal rights to provide and to charge for the ambulant services that are included in this agreement. These conditions will play a role in the daily routine of hospitals and will influence treatment patterns. A comprehensive knowledge of the basic principles is essential. In the present article, the compulsory agreement and some resulting consequences are elucidated with special relevance to gastroenterology.


Subject(s)
Ambulatory Surgical Procedures/legislation & jurisprudence , Ambulatory Surgical Procedures/standards , Patient Care Management/legislation & jurisprudence , Patient Care Management/standards , Quality Assurance, Health Care/legislation & jurisprudence , Quality Assurance, Health Care/standards , Ambulatory Surgical Procedures/economics , Digestive System Surgical Procedures/economics , Digestive System Surgical Procedures/legislation & jurisprudence , Digestive System Surgical Procedures/standards , Documentation/standards , Germany , Humans , Inpatients , Patient Care Management/economics , Quality Assurance, Health Care/economics
10.
Hautarzt ; 55(7): 667-75, 2004 Jul.
Article in German | MEDLINE | ID: mdl-15168028

ABSTRACT

Since January 2004, German hospitals and specialists in private practice have equal rights to provide and to charge for ambulatory surgeries according to paragraph 115b, 5th Code of Social Law. The current agreement between the German self-governing bodies replaces the existing contracts from 1993. In contrast to the previous version, the revised catalogue contains additional non-operative procedures. Some procedures may be provided either in an ambulatory or inpatient setting. However, for the hospitals it is of particular importance that some specified procedures should be performed on an ambulatory basis. If these particular services are delivered in an inpatient setting at least one stipulated criteria of exception has to be fulfilled. From the perspective of dermatology, not only opportunities but also obligations for ambulatory care arise from the new conditions. The critical facts and aspects with special relevance to dermatology are reviewed in detail.


Subject(s)
Ambulatory Surgical Procedures/legislation & jurisprudence , National Health Programs/legislation & jurisprudence , Patient Admission/legislation & jurisprudence , Reimbursement Mechanisms/legislation & jurisprudence , Skin Diseases/surgery , Cost Savings/legislation & jurisprudence , Diagnosis-Related Groups/legislation & jurisprudence , Germany , Humans
11.
Chirurg ; 74(12): 1149-55, 2003 Dec.
Article in German | MEDLINE | ID: mdl-14673538

ABSTRACT

The new hospital funding system based on a diagnosis-related group (DRG) system and the economic competition involved require large-scale changes in hospital structures and processes. Clinical pathways are multidisciplinary plans of best clinical practice for specified groups of patients with a particular diagnosis that aid the coordination and delivery of high quality care. The clinical pathway originally used in the USA and Australia was aimed at shortening the hospital stay and reducing healthcare costs, which has become an increasingly important issue in medicine. Furthermore, it is an appropriate tool to standardize medical care and increase patient satisfaction. Clinical pathways are able to standardize care for patients with a similar diagnosis, procedure, or symptom. There are four essential components of a clinical pathway: a timeline, the categories of care or activities and their interventions, intermediate- and long-term outcome criteria, and the variance record. In contrast to practice guidelines, protocols, and algorithms, clinical pathways are utilized by a multidisciplinary team and focus on quality and coordination of care.


Subject(s)
Diagnosis-Related Groups , Algorithms , Delivery of Health Care/organization & administration , Diagnosis-Related Groups/economics , Diagnosis-Related Groups/standards , Health Care Costs , Humans , Length of Stay , Patient Satisfaction , Process Assessment, Health Care , Quality Assurance, Health Care , Quality of Health Care
12.
Exp Dermatol ; 12(4): 490-6, 2003 Aug.
Article in English | MEDLINE | ID: mdl-12930307

ABSTRACT

To follow up the novel psoriasis susceptibility region on chromosome 19 (PSORS6), we performed an association scan for psoriasis vulgaris using 45 evenly spaced DNA microsatellite markers. For this study, a new independent sample of 210 nuclear psoriasis families (trio design) from Northern Germany was recruited. We used the family based association test (FBAT) for an association scan over the chromosome 19 region encompassing 50.8 cM. We obtained a positive association for the markers D19S922 (allele 5, P = 0.008) and D19S916 (allele 13, P = 0.016), which correspond to the peak of the region identified in a previously performed scan. We identified two novel regions by a single marker, each showing negative association at D19S917 on 19p13.1 (allele 8, P = 0.0034) and at D19S425 (allele 9, P = 0.0005), compatible with the hypothesis of protective loci. These two novel regions were explored in more detail using novel microsatellite markers at an average distance of 100 kb. A separate analysis distinguishing between familial (n = 137) and sporadic (n = 73) psoriasis families showed that the familial trios contribute strongly in the region around D19S425 (P = 0.004), while the comparably small subset of 73 sporadic trios has a stronger effect at the locus around D19S917 (P = 0.026). These studies confirm the existence of a psoriasis susceptibility locus on chromosome 19 and give first evidence for the existence of both susceptible and protective loci in this region. Analysis of a dense marker set from these refined regions will eventually allow identification of the underlying susceptibility alleles.


Subject(s)
Chromosomes, Human, Pair 19/genetics , Psoriasis/genetics , Alleles , Chromosome Mapping , Female , Humans , Male , Microsatellite Repeats
13.
Br J Dermatol ; 149(2): 381-5, 2003 Aug.
Article in English | MEDLINE | ID: mdl-12932247

ABSTRACT

BACKGROUND: The anti-inflammatory cytokine interleukin (IL)-10 is considered to play a major role in the pathophysiology of psoriasis, which is characterized by an IL-10 deficiency. Systemic administration of IL-10 has been shown to be an effective therapy for psoriasis. The IL-10 promoter region contains a highly polymorphic microsatellite (IL10.G) and in a recent case-control study the IL10.G13 (144 bp) allele was found to be associated with familial early onset psoriasis (type 1 psoriasis) having a susceptible effect. OBJECTIVES: As it is essential in multifactorial diseases to replicate findings before definite conclusions can be drawn, we decided to perform a follow-up study and to follow a genetic approach analysing allele transmission in families with a positive family history of psoriasis. METHODS: We studied 137 nuclear families (trio-design) comprising 456 individuals and genotyped the IL10.G marker. For comparison we also genotyped the microsatellite tn62 as a reference marker of the major psoriasis susceptibility locus on chromosome 6p21 (PSORS1). In the present study allele transmission was evaluated using the family-based association test (FBAT) and GENEHUNTER 2.0 based on the transmission/disequilibrium test. RESULTS: The G13 allele (144 bp) had a frequency of 24%, was present in 88 families and clearly showed an even transmission (FBAT, P = 0.753). In contrast, allele 3 (IL10.G9) (136 bp) had a frequency of 39%, was present in 110 families and was transmitted in 43 trios and remained untransmitted in 67 trios (FBAT, P = 0.026), thus showing preferential nontransmission. For the HLA-linked tn62-marker we obtained a P-value of 0.00027 for allele 4 in the same study group. CONCLUSIONS: In conclusion, we failed to confirm the susceptible effect of the G13 allele, but provide the first data for a protective effect of allele 3 (IL10.G9) for familial psoriasis. Our results suggest that the IL10.G polymorphism is not a major locus, but acts as a minor locus.


Subject(s)
Genetic Predisposition to Disease , Interleukin-10/genetics , Polymorphism, Genetic , Promoter Regions, Genetic/genetics , Psoriasis/genetics , Alleles , Female , Follow-Up Studies , Genetic Markers , Genotype , Humans , Male , Microsatellite Repeats/genetics
14.
Pediatrics ; 103(3): 678-83, 1999 Mar.
Article in English | MEDLINE | ID: mdl-10049979

ABSTRACT

OBJECTIVE: To describe prenatal genetic diagnosis in hyperprostaglandin E syndrome (HPS) and the effect of indomethacin therapy on the course of the disease before birth and in the neonatal period. METHODS: Mutational analysis of the ROMK channel gene (KCNJ1) from amniocytes by single-strand conformational analysis and direct sequencing. Review of the clinical and laboratory findings during pregnancy and the neonatal period in two siblings affected with HPS. RESULTS: Compound heterozygosity of the fetus in KCNJ1 (D74Y/P110L) confirmed the clinical diagnosis of HPS at 26 weeks of gestation. Indomethacin therapy from 26 to 31 weeks prevented further progression of polyhydramnios without major side effects. In contrast to the elder brother, who had been diagnosed at the age of 2 months, the neonatal course was uncomplicated. Hypovolemic renal failure after excessive renal loss of salt and water could be prevented and severe nephrocalcinosis did not occur. CONCLUSIONS: Genetic diagnosis of HPS and subsequent prenatal indomethacin therapy seems to have a beneficial effect on the natural course of HPS, especially progression of polyhydramnios; therefore, extreme prematurity could be prevented. Also, postnatally the early diagnosis allows the effective water and electrolyte substitution before severe volume depletion.


Subject(s)
Amniotic Fluid/cytology , Bartter Syndrome/genetics , DNA Mutational Analysis , Prenatal Diagnosis , Prostaglandins E/blood , Bartter Syndrome/diagnosis , Bartter Syndrome/diagnostic imaging , Female , Humans , Indomethacin/therapeutic use , Infant, Newborn , Kidney/diagnostic imaging , Male , Polyhydramnios/drug therapy , Polymorphism, Single-Stranded Conformational , Potassium Channels , Pregnancy , Syndrome , Ultrasonography
15.
J Biol Chem ; 273(37): 23884-91, 1998 Sep 11.
Article in English | MEDLINE | ID: mdl-9727001

ABSTRACT

Loss of function mutations in kidney Kir1.1 (renal outer medullary potassium channel, KCNJ1) inwardly rectifying potassium channels can be found in patients suffering from hyperprostaglandin E syndrome (HPS), the antenatal form of Bartter syndrome. A novel mutation found in a sporadic case substitutes an asparagine by a positively charged lysine residue at amino acid position 124 in the extracellular M1-H5 linker region. When heterologously expressed in Xenopus oocytes and mammalian cells, current amplitudes from mutant Kir1.1a[N124K] channels were reduced by a factor of approximately 12 as compared with wild type. A lysine at the equivalent position is present in only one of the known Kir subunits, the newly identified Kir1.3, which is also poorly expressed in the recombinant system. When the lysine residue in guinea pig Kir1.3 (gpKir1.3) isolated from a genomic library was changed to an asparagine (reverse HPS mutation), mutant channels yielded macroscopic currents with amplitudes increased 6-fold. From single channel analysis it became apparent that the decrease in mutant Kir1.1 channels and the increase in mutant gpKir1.3 macroscopic currents were mainly due to the number of expressed functional channels. Coexpression experiments revealed a dominant-negative effect of Kir1.1a[N124K] and gpKir1.3 on macroscopic current amplitudes when coexpressed with wild type Kir1.1a and gpKir[K110N], respectively. Thus we postulate that in Kir1.3 channels the extracellular positively charged lysine is of crucial functional importance. The HPS phenotype in man can be explained by the lower expression of functional channels by the Kir1. 1a[N124K] mutant.


Subject(s)
Bartter Syndrome/genetics , Kidney Medulla/metabolism , Point Mutation , Potassium Channels, Inwardly Rectifying , Potassium Channels/genetics , Potassium Channels/physiology , Amino Acid Sequence , Animals , Bartter Syndrome/embryology , COS Cells , Cloning, Molecular , Female , Humans , Molecular Sequence Data , Mutagenesis, Site-Directed , Oocytes/physiology , Polymerase Chain Reaction , Polymorphism, Single-Stranded Conformational , Potassium Channels/chemistry , Prostaglandins E/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Sequence Alignment , Sequence Homology, Amino Acid , Syndrome , Transfection , Xenopus laevis
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