Treatment of ichthyophthiriasis with photodynamically active chlorophyllin

Water-soluble chlorophyll (chlorophyllin) exerts pronounced photodynamic activity on fish parasites. In order to determine its potential as a remedy against ectoparasites in fish carps were incubated in water with defined concentrations of chlorophyllin. The main focus of the experiments was on the ciliate Ichthyophthirius multifiliis (Fouquet) which is responsible for considerable losses in livestock in aquaculture. As malachite green, which in the past efficiently cured infected fishes, is banned because of its possible carcinogenicity; no effective remedy is presently available in aquaculture to treat ichthyophthiriasis. Using chlorophyllin, the number of trophonts was significantly reduced (more than 50 %) after 3 h incubation of infested fish at 2 and 4 mg/L and subsequent irradiation with simulated solar radiation. The lack of reinfection after light treatment indicates that also the remaining parasites have lost their multiplication capacity. In the controls (no chlorophyllin and no light, light but no chlorophyllin, or chlorophyllin but no light), no reduction of the I. multifiliis infection was observed. We propose that chlorophyllin (or other photodynamic substances) is a possible effective countermeasure against I. multifiliis and other ectoparasites in aquaculture.

Frühwarnsystem zur Flüssigkeitsüberwachung der Lunge bei terminaler Herzinsuffizienz

HISTORY AND ADMISSION FINDINGS

A 38-year-old man was admitted for increasing dyspnea, nausea and emesis during the preceding year. Clinically he was in heart failure NYHA stage III. He had not been on any regular medication and had no other medical complaints. Physical examination revealed a pulse of 100/min., hypotension (100/60 mmHg) and jugular vein distension. Bilateral pulmonary rales were noted on auscultation. A slight edema of both lower legs was noted.

INVESTIGATIONS

A 12-lead electrocardiogram showed complete left bundle branch block with a QRS duration of 160 ms. Chest x-ray revealed cardiomegaly with pulmonary vascular congestion. Transthoracic echocardiography demonstrated reduced left ventricular function with an ejection fraction of 10-15%. Left heart catheterization excluded coronary heart disease and confirmed the decreased left ventricular function.

TREATMENT AND COURSE

Medical treatment for heart failure secondary to dilated cardiomyopathy was initiated without significant improvement in clinical status. Cardiac resynchronization therapy (CRT) was therefore performed with implantation of a biventricular pacer with defibrillator (CRT-D) and a fluid status monitoring system (OptiVol). Subsequently the patient was able to increase his physical activity to NYHA class II and was followed in our outpatient clinic. Since initial treatment the patient has been seen twice for clinical signs of pulmonary edema. Both times the fluid monitoring system of the CRT-D gave an alarm signal early enough to allow cardiac re-compensation by expanding the current medication. Both times hospital admission was avoided.

CONCLUSIONS

Cardiac resynchronization therapy has been established as an adjunct to optimal pharmacological therapy in eligible patients with severe heart failure. A fluid status monitoring system integrated into the device measures intrathoracic impedance, allowing patients to be alerted before the onset of symptoms of fluid overload. Thus, treatment can be adjusted and hospitalization is avoidable.

Transvenous ICD implantation after artificial tricuspid valve replacement

Implantation of a transvenous device in patients with a tricuspid valve replacement or a complex congenital heart disease with no access to the right ventricle represents problems. The lack of access to the right ventricle might preclude transvenous placement of a defibrillation lead at ICD implantation. A young patient (21 years) with a history of severe chest trauma with rupture of the tricuspid valve as well as the right coronary artery and consecutive inferior myocardial infarction was initially treated with tricuspid valve replacement (St Jude Medical artificial prosthesis, 33 mm) and a bypass graft to the right coronary artery. Four years later, the patient was admitted with a hemodynamically not tolerated ventricular tachycardia (VT: CL 250 ms, LBBB, left axis). The VT could be reproduced during electrophysiological testing. An ICD was implanted subpectorally in combination with a transvenous active fixation ICD lead. The transvenous ICD lead was placed via a guiding catheter into a coronary sinus branch (middle cardiac vein). Acceptable pacing and sensing values could be obtained. The defibrillation threshold was 25 J. In conclusion transvenous ICD lead implantation into a side branch of the coronary sinus in combination with a pectorally implanted "active can" ICD device seems to be an alternative approach. This approach may avoid implantation of additional subcutaneous defibrillation leads or even thoracotomy for ICD implantation.

Effective long-term control of cardiac events with beta-blockers in a family with a common LQT1 mutation

The congenital long QT syndrome (LQTS) is characterized by a prolonged QT interval on the surface electrocardiogram and an increased risk of recurrent syncope and sudden cardiac death. Mutations in seven genes have been identified as the molecular basis of LQTS. beta-blockers are the treatment of choice to reduce cardiac symptoms. However, long-term follow-up of genotyped families with LQTS has been rarely reported. We have clinically followed a four-generation family with LQTS being treated with beta-blocker therapy over a period of 23 years. Seven family members were carriers of two amino acid alterations in cis (V254M-V417M) in the cardiac potassium channel gene KCNQ1. Voltage-clamp recordings of mutant KCNQ1 protein in Xenopus oocytes showed that only the V254M mutation reduced the IKs current and that the effect of the V417M variant was negligible. The family exhibited the complete clinical spectrum of the disease, from asymptomatic patients to victims of sudden death before beta-blocker therapy. There was no significant reduction in QTc (556 +/- 40 ms(1/2) before therapy, 494 +/- 20 ms(1/2) during 17 years of treatment; n = 5 individuals). Of nine family members, one female died suddenly before treatment, three females of the second generation were asymptomatic, and four individuals of the third and fourth generation were symptomatic. All mutation carriers were treated with beta-blockers and remained asymptomatic for a follow-up up to 23 years. Long-term follow-up of a LQT1 family with a common mutation (V254M) being on beta-blocker therapy was effective and safe. This study underscores the importance of long-term follow-up in families with specific LQT mutations to provide valuable information for clinicians for an appropriate antiarrhythmic treatment.

Long QT syndrome and life threatening arrhythmia in a newborn: molecular diagnosis and treatment response

Intrauterine and neonatal manifestations of congenital long QT syndrome are associated with a high cardiac risk, particularly when atrioventricular block and excessive QT prolongation (> 600 ms(1/2)) are present. In a female newborn with these features, treatment with propranolol and mexiletine led to complete reduction of arrhythmia that was maintained 1.5 years later. High throughput genetic analysis found a sodium channel gene (LQT3) mutation. Disappearance of the 2:1 atrioventricular block and QTc shortening (from 740 ms(1/2) to 480 ms(1/2)), however, was achieved when mexiletine was added to propranolol. This effect was considered to be possibly genotype related. Early onset forms of long QT syndrome may benefit from advanced genotyping.

Pathological changes of the heart in sudden infant death

There are more than 120 different theories on the possible causes of sudden infant death (SID). In particular, dysfunctions of the central nervous system, cardiorespiratory insufficiency due to infections including atypical immune reactions, and cardiac dysregulation have been discussed during the previous decade. Reports on disturbances of the cardiac rhythmogenic function due to LQTS were among the most speculative. Based on gross histological, immunohistochemical and molecular genetic investigations of SID cases, the most important and most frequent findings of the heart are shown. The significance of different types of myocarditis, hypoxia-related changes, disturbances of the rhythmogenic function, cardiomyopathy, and other changes is discussed with regard to the cause of death. In conclusion, most of the changes reported in the literature are not sufficient to explain the cause of death. Problems in the diagnosis are shown which influence the classification of these disturbances as well as the classification of SID.

[Clinical aspects and molecular genetics of the Jervell- and Lange-Nielsen Syndrome]

In contrast to the Romano-Ward (R-W) syndrome, the Jervell and Lange-Nielsen (J-LN) syndrome is an autosomal recessive inherited disease characterized by QT-prolongation in the electrocardiogram (ECG) and recurrent syncopal attacks which are also typical for the R-W syndrome, but also by congenital deafness. Recently, defect alleles in the genes for KCNQ1 and KCNE1 have been identified in patients with the J-LN syndrome. These genes may be causative for the R-W syndrome as well but in J-LN patients, they are only present in the homozygote or compound heterozygote form. In the present paper, we review the clinical and genetic similarities and differences of the J-LN and the R-W syndrome as well as the diagnostic and therapeutic management of these patients and their family members.

Molecular diagnosis in a child with sudden infant death syndrome

Although sudden infant death syndrome (SIDS) has been associated with long QT syndrome-a genetic disorder that causes arrhythmia-a causal link has not been shown. We screened genomic DNA from a child who died of SIDS and identified a de-novo mutation in KVLQT1, the gene most frequently associated with long QT syndrome. This mutation (C350T) had already been identified in an unrelated family that was affected by long QT syndrome. These results confirm the hypothesis that some deaths from SIDS are caused by long QT syndrome and support implementation of neonatal electrocardiographic screening.

De novo mutation in the SCN5A gene associated with early onset of sudden infant death

BACKGROUND

Congenital long QT syndrome (LQTS), a cardiac ion channel disease, is an important cause of sudden cardiac death. Prolongation of the QT interval has recently been associated with sudden infant death syndrome, which is the leading cause of death among infants between 1 week and 1 year of age. Available data suggest that early onset of congenital LQTS may contribute to premature sudden cardiac death in otherwise healthy infants.

METHODS AND RESULTS

In an infant who died suddenly at the age of 9 weeks, we performed mutation screening in all known LQTS genes. In the surface ECG soon after birth, a prolonged QTc interval (600 ms(1/2)) and polymorphic ventricular tachyarrhythmias were documented. Mutational analysis identified a missense mutation (Ala1330Pro) in the cardiac sodium channel gene SCN5A, which was absent in both parents. Subsequent genetic testing confirmed paternity, thus suggesting a de novo origin. Voltage-clamp recordings of recombinant A1330P mutant channel expressed in HEK-293 cells showed a positive shift in voltage dependence of inactivation, a slowing of the time course of inactivation, and a faster recovery from inactivation.

CONCLUSIONS

In this study, we report a de novo mutation in the sodium channel gene SCN5A, which is associated with sudden infant death. The altered functional characteristics of the mutant channel was different from previously reported LQTS3 mutants and caused a delay in final repolarization. Even in families without a history of LQTS, de novo mutations in cardiac ion channel genes may lead to sudden cardiac death in very young infants.

A novel long-QT 5 gene mutation in the C-terminus (V109I) is associated with a mild phenotype

Mutations in the human minK gene KCNE1 have been linked to autosomal dominant and autosomal recessive long-QT (LQT) syndrome, a cardiac condition predisposing to ventricular arrhythmias. minK and KvLQT1, the LQT1 gene product, form a native cardiac K+ channel that regulates the slowly delayed rectifier potassium current I(Ks). We used single-strand conformation polymorphism and sequencing techniques to identify novel KCNE1 mutations in patients with a congenital LQT syndrome of unknown genetic origin. In 150 unrelated index patients a missense mutation (V109I) was identified that significantly reduced the wild-type I(Ks) current amplitude (by 36%) when coexpressed with KvLQT1 in Xenopus oocytes. Other biophysical properties of the I(Ks) channel were not altered. Since we observed incomplete penetrance (only one of two mutation carriers could be diagnosed by clinical criteria), and the family's history was unremarkable for sudden cardiac death, the 109I allele most likely causes a mild phenotype. This finding may have implications for the occurrence of "acquired" conditions for ventricular arrhythmias and thereby the potential cardiac risk for asymptomatic mutation carriers still remains to be determined.

Clinical value of electrocardiographic parameters in genotyped individuals with familial long QT syndrome

Rate corrected QT interval (QTc) and QT dispersion (QTd) have been suggested as markers of an increased propensity to arrhythmic events and efficacy of therapy in patients with long QT syndrome (LQTS). To evaluate whether QTc and QTd correlate to genetic status and clinical symptoms in LQTS patients and their relatives, ECGs of 116 genotyped individuals were analyzed. JTc and QTc were longest in symptomatic patients (n = 28). Both QTd and JTd were significantly higher in symptomatic patients than in asymptomatic (n = 29) or unaffected family members (n = 59). The product of QTd/JTd and QTc/JTc was significantly different among all three groups. Both dispersion and product put additional and independent power on identification of mutation carriers when adjusted for sex and age in a logistic regression analysis. Thus, symptomatic patients with LQTS show marked inhomogenity of repolarization in the surface ECG. QT dispersion and QT product might be helpful in finding LQTS mutation carriers and might serve as additional ECG tools to identify asymptomatic LQTS patients.

[New knowledge in arrhythmogenesis--role of ion channels and genetic aspects]

Recent advances in molecular biology have had a major impact on our understanding of the mechanisms of human diseases. Electrophysiology is one of the areas which, besides others, has substantially benefited from this development. Our understanding of the structure, function and mechanisms of the regulation of ion channels as well as their contribution to the pathogenesis of cardiac arrhythmias has substantially increased. The results of these studies are not only of special interest from the scientific point of view. It is likely to assume that, in the future, they will increasingly influence the diagnosis and treatment of arrhythmias.

Prolonged QT interval and sudden infant death--report of two cases

In the two cases where infants died suddenly and unexpectedly the electrocardiogram (ECG) of a younger sibling (case 1) and of a living twin (case 2) led to the suspicion that the two infants could have died from long QT syndrome (LQTS). In case 1, a His bundle (HB) dispersion and a pronounced hypoplasia of the right external nucleus arcuatus were detected. In case 2, a severe interstitial pneumonia and an accompanying mild myocarditis were found by histology. Molecular genetic investigations of the coding regions of the genes, HERG, KVLQT1 and SCN5A gave no indication for the mutations, thus, affecting related myocardial ion channels as possible sources of inhomogeneity of repolarisation. Since a molecular genetic deviation could not yet be elaborated the possible role of related disturbance remains unknown.

Molecular genetics of arrhythmias--a new paradigm

The molecular genetic background of inherited cardiac arrhythmias has only recently been uncovered. This late development in comparison to other inherited cardiac disorders has partly been due to the high mortality and early disease onset of these arrhythmias resulting in mostly small nucleus families. Thus, traditional genetic linkage studies, which are based on the genetic information obtained from large multi-generation families, were made difficult. Inherited arrhythmogenic disorders can be divided into 'primary electrical disorders' (e.g., long-QT [LQT] syndrome) in which a detectable, organic heart disease is not evident, and into inherited diseases of the myocardial structure (e.g., hypertrophic cardiomyopathies) in which the arrhythmias occur combined with the structural alterations. To date, all inherited arrhythmogenic disorders in which the causative genes have been identified turned out to be channelopathies, since the genes encode channel subunits that regulate important ion currents that tune the cardiac action potential. The discovery of the genetic bases of the LQT syndrome became a new methodologic paradigm; because with the use of 'classical' genetic linkage strategies (named [positional] candidate strategies) not only the causative genes have been found, but moreover, functional components with a previously unknown but fundamental role for a normal repolarization process were discovered. Disease mutations turned out to be not only a family-specific event with a distinct phenotype and the potential of an additional diagnostic tool, but also, when expressed in heterologous expression systems, characterize the defective ion channel in a topological way and lead to a more specific understanding of ion channel function. Most, if not all, primary electrical cardiac disorders show a high genetic diversity. For the LQT syndromes, sixth disease loci and the responsible gene have been recently discovered (so-called locus or genetic heterogeneity). Within all disease genes, the mutations are spread over the entire gene (allelic heterogeneity); in addition, more than one disease mutation may be present. This complexity requires, at least, complete mutation analysis of all LQT genes before medical advice should be given. Meanwhile, genotype-phenotype correlations in large families are being used to evaluate intergene, interfamilial and intrafamilial differences in the clinical phenotype, reflecting gene specific, gene-site specific and individual consequences of a given mutation. A widespread phenotypic heterogeneity even within mutation carriers in the same family raises the importance of modifying factors and genes that are mostly unknown to date. The reduced penetrance and variable expressivity associated with the LQT mutations remain still to be explained. First insights into the complex actions of mutations are being extracted, from expression data; these preliminary results may lead to potential implications for a specific (gene-site directed) therapy. This paper discusses the current data on molecular genetics and genotype-phenotype correlations in LQT syndrome and related disorders and the potential implications for diagnosis and treatment.

The LQT syndromes--current status of molecular mechanisms

Our knowledge on the molecular genetics of inherited cardiac arrhythmias is very recent in comparison to the advances of genetics achieved in other inherited cardiac disorders. This is related to the high mortality and early disease onset of these arrhythmias resulting in mostly small nucleus families. Thus, traditional genetic linkage studies that are based on the genetic information obtained from large multi-generation families were made difficult. In 1991, the first chromosomal locus for congenital long-QT (LQT) syndrome was identified on chromosome 11p15.5 (LQT1 locus) by linkage analysis. Meanwhile, the disease-causing gene at the LQT1 locus (KCNQ1), a gene encoding a K+ channel subunit of the IKs channel, and three other, major genes, all encoding cardiac ion channel components, have been identified. Taken together, LQT syndrome turned out to be a heterogeneous channelopathy. Moreover, the power of linkage studies to reveal the genetic causes of the LQT syndrome was also important to identify unknown but fundamental channel components that contribute to the ion currents tuning ventricular repolarization. In-vitro expression of the altered ion channel genes demonstrated in each case that the altered ion channel function produces prolongation of the action potential and thus the increasing propensity to ventricular tachyarrhythmias. Since these ion channels are pharmacological targets of many antiarrhythmic (and other) drugs, individual and potentially deleterious drug responses may be related to genetic variation in ion channel genes. Very recently, also in acquired LQT syndrome, which is a frequent clinical disorder in cardiology a genetic basis has been proposed in part since mutations in LQT genes have been specifically found. The discovery of ion channel defects in LQT syndrome represents the major achievement in our understanding and implies potential therapeutic options. The knowledge of the genomic structure of the LQT genes now offers the possibility to detect the underlying genetic defect in 80-90% of all patients. With this specific information, containing the type of ion channel (Na+ versus K+ channel) and electrophysiological alteration by the mutation (loss-of-function versus change-of-function mutation), gene-directed, elective drug therapies have been initiated in genotyped LQT patients. Based on preliminary data, that were supported by in vitro studies, this approach may be useful in recompensating the characteristic phenotypes in some LQT patients. Mutation detection is a new diagnostic tool which may become of more increasing importance in patients with a normal QTc or just a borderline prolongation of the QTc interval at presentation. These patients represent approximately 40% of all familial cases. Moreover, LQT3 syndrome and idiopathic ventricular fibrillation are allelic disorders and genetically overlap. In both mutations in the LQT3 gene SCN5A encoding the Na+ channel alpha-subunit for INa have been reported. Thus, the clinical nosology of inherited arrhythmias may be reconsidered after elucidation of the underlying molecular bases. Meanwhile, genotype-phenotype correlations in large families are on the way to evaluate intergene, interfamilial, and intrafamilial differences in the clinical phenotype reflecting gene specific, gene-site specific, and individual consequences of a given mutation. LQT syndrome is phenotypically heterogeneous due to the reduced penetrance and variable expressivity associated with the mutations. This paper discusses the current data on molecular genetics and genotype-phenotype correlations and the implications for diagnosis and treatment.

Autosomal recessive long-QT syndrome (Jervell Lange-Nielsen syndrome) is genetically heterogeneous

Jervell Lange-Nielsen syndrome (JLNS) is a recessive disorder with congenital deafness and long-QT syndrome (LQTS 1). Mutations in the potassium-channel gene KVLQT1 (LQTS 1) have been identified in JLNS and in autosomal-dominant LQTS as well. We performed haplotype analysis with microsatellite markers in a Lebanese family with JLNS, but failed to detect linkage at LQTS 1. Moreover, using this approach, we excluded two other ion-channel genes involved in autosomal-dominant LQTS, HERG (LQTS 2) and SCN5A (LQTS 3). Our findings indicate that JLNS is genetically heterogeneous and that, in this family, an unknown LQTS gene causes the disease.

Mapping of a gene for familial juvenile nephronophthisis: refining the map and defining flanking markers on chromosome 2. APN Study Group

Familial juvenile nephronophthisis (NPH) is an autosomal recessive kidney disease that leads to end-stage renal failure in adolescence and is associated with the formation of cysts at the cortico-medullary junction of the kidneys. NPH is responsible for about 15% of end-stage renal disease in children, as shown by Kleinknecht and Habib. NPH in combination with autosomal recessive retinitis pigmentosa is known as the Senior-Løken syndrome (SLS) and exhibits renal pathology that is identical to NPH. We had excluded 40% of the human genome from linkage with a disease locus for NPH or SLS when Antignac et al. first demonstrated linkage for an NPH locus on chromosome 2. We present confirmation of linkage of an NPH locus to microsatellite markers on chromosome 2 in nine families with NPH. By linkage analysis with marker AFM262xb5 at locus D2S176, a maximum lod score of 5.05 at a theta max = .03 was obtained. In a large NPH family that yielded at D2S176 a maximum lod score of 2.66 at theta max = .0, markers AFM172xc3 and AFM016yc5, representing loci D2S135 and D2S110, respectively, were identified as flanking markers, thereby defining the interval for an NPH locus to a region of approximately 15 cM. Furthermore, the cytogenetic assignment of the NPH region was specified to 2p12-(2q13 or adjacent bands) by calculation of linkage between these flanking markers and markers with known unique cytogenetic assignment. The refined map may serve as a genetic framework for additional genetic and physical mapping of the region.