Clinical outcome of idiopathic juvenile ventricular arrhythmias in 25 dogs

INTRODUCTION/OBJECTIVES

Juvenile ventricular arrhythmias in the absence of structural heart disease have been characterized in a small number of canine breeds with limited long-term follow up. The objective of this study was to describe the clinical outcome of dogs with JVA presenting to a university teaching hospital.

ANIMALS, MATERIALS, METHODS

25 dogs, less than two years old with idiopathic ventricular arrhythmias were retrospectively identified via a medical record search. Young dogs with ventricular arrhythmias were excluded if they had structural heart disease, systemic illness, or an abnormal troponin (if performed). Electrocardiographic and Holter monitor data was evaluated for arrhythmia frequency and complexity at the time of diagnosis and over time. Long-term follow up was achieved through client and primary veterinarian contact.

RESULTS

Breeds included German Shepherd (8), Boxer (4), Great Dane (3), mixed breed (2) and one each of the following: Anatolian Shepherd, French Bulldog, Golden Retriever, Great Pyrenees, Labrador Retriever, Shiloh Shepherd, Miniature Poodle and Siberian Husky. The average age at diagnosis was 7.9 months (range, 2-22 months). The overall median survival was 10.96 years (range, 1.75-15.66 years). There was an average reduction in the number of ventricular beats by 86.7 % per year (P value -0.0257) based on Holter data.

CONCLUSION

In most cases, idiopathic juvenile ventricular arrhythmias had a favorable long-term prognosis with reduced ectopy over time in this case series. Juvenile ventricular arrhythmias remains a diagnosis of exclusion but can be considered in a broader range of dog breeds than previously described.

Causes of loss to follow-up from drug-resistant TB treatment in Khayelitsha, South Africa

Patients initiated on drug-resistant TB(DR-TB) treatment in 2019 in Khayelitsha, South Africa, with a loss to follow-up outcome were evaluated to better understand reasons for loss to follow-up and to determine if any had returned to care. Of a total of 187 patients, 28 (15%) were lost to follow-up (LTFU), 24 (86%) of whom were traced: 20/24 (83%) were found when they re-presented to facilities and 8/28 (29%) were linked back to DR-TB care. People with DR-TB continue to seek care even after being LTFU; thus better coordination between different components of the healthcare system are required to re-engage with these patients. Interventions to mitigate the socio-economic challenges of people on DR-TB treatment are needed. Many people who were LTFU and symptomatic were willing to re-engage with DR-TB care, which highlights the importance of for compassionate interventions to welcome them back.

Early mortality during rifampicin-resistant TB treatment

BACKGROUND: Data suggest that treatment with newer TB drugs (linezolid [LZD], bedaquiline [BDQ] and delamanid [DLM]), used in Khayelitsha, South Africa, since 2012, reduces mortality due to rifampicin-resistant TB (RR-TB).METHODS: This was a retrospective cohort study to assess 6-month mortality among RR-TB patients diagnosed between 2008 and 2019.RESULTS: By 6 months, 236/2,008 (12%) patients died; 12% (78/651) among those diagnosed in 2008-2011, and respectively 8% (49/619) and 15% (109/738) with and without LZD/BDQ/DLM in 2012-2019. Multivariable analysis showed a small, non-significant mortality reduction with LZD/BDQ/DLM use compared to the 2008-2011 period (aOR 0.79, 95% CI 0.5-1.2). Inpatient treatment initiation (aOR 3.2, 95% CI 2.4-4.4), fluoroquinolone (FQ) resistance (aOR 2.7, 95% CI 1.8-4.2) and female sex (aOR 1.5, 95% CI 1.1-2.0) were also associated with mortality. When restricted to 2012-2019, use of LZD/BDQ/DLM was associated with lower mortality (aOR 0.58, 95% CI 0.39-0.87).CONCLUSIONS: While LZD/BDQ/DLM reduced 6-month mortality between 2012 and 2019, there was no significant effect overall. These findings may be due to initially restricted LZD/BDQ/DLM use for those with high-level resistance or treatment failure. Additional contributors include increased treatment initiation among individuals who would have otherwise died before treatment due to universal drug susceptibility testing from 2012, an effect that also likely contributed to higher mortality among females (survival through to care-seeking).

Clinical perspectives on treatment of rifampicin-resistant/multidrug-resistant TB

Rapid diagnostics, newer drugs, repurposed medications, and shorter regimens have radically altered the landscape for treating rifampicin-resistant TB (RR-TB) and multidrug-resistant TB (MDR-TB). There are multiple ongoing clinical trials aiming to build a robust evidence base to guide RR/MDR-TB treatment, and both observational studies and programmatic data have contributed to advancing the treatment field. In December 2019, the WHO issued their second 'Rapid Communication´ related to RR-TB management. This reiterated their prior recommendation that a majority of people with RR/MDR-TB receive all-oral treatment regimens, and now allow for specific shorter duration regimens to be used programmatically as well. Many TB programs need clinical advice as they seek to roll out such regimens in their specific setting. In this Perspective, we highlight our early experiences and lessons learned from working with National TB Programs, adult and pediatric clinicians and civil society, in optimizing treatment of RR/MDR-TB, using shorter, highly-effective, oral regimens for the majority of people with RR/MDR-TB.

Implementing novel regimens for drug-resistant TB in South Africa: what can the world learn?

Worldwide uptake of new drugs in the treatment of rifampicin-resistant tuberculosis (RR-TB) has been extremely low. In June 2018, ahead of the release of the updated WHO guidelines for the management of RR-TB, South Africa announced that bedaquiline (BDQ) would be provided to virtually all RR-TB patients on shorter or longer regimens. South Africa has been the global leader in accessing BDQ for patients with RR-TB, who now represent 60% of the global BDQ cohort. The use of BDQ within a shorter modified regimen has generated the programmatic data underpinning the most recent change in WHO guidelines endorsing a shorter, injectable-free regimen. Progressive policies on access to new drugs have resulted in improved favourable outcomes and a reduction in mortality among RR-TB patients in South Africa. This supported global policy change. The strategies underpinning these bold actions include close collaboration between the South African National TB Programme and partners, introduction of new TB diagnostic tools in closely monitored conditions and the use of locally generated programmatic evidence to inform country policy changes. In this paper, we summarise a decade´s work that led to the bold decision to use a modified, short, injectable-free regimen with BDQ and linezolid under carefully monitored programmatic conditions.

Adverse events among people on delamanid for rifampicin-resistant tuberculosis in a high HIV prevalence setting

SETTING: Patients with rifampicin-resistant tuberculosis (RR-TB) in the township of Khayelitsha, South Africa, were offered delamanid (DLM) within a decentralised RR-TB treatment programme.OBJECTIVE: To describe adverse events (AEs) among HIV-positive and negative people receiving DLM for RR-TB in a programmatic setting.DESIGN: Patients were followed up monthly for blood, electrocardiography and clinical monitoring and AEs were assessed for severity grade, seriousness and relationship to DLM.RESULTS: Fifty-eight patients (55% male; median age 35 years, interquartile range [IQR] 28-42) started DLM; 46 (79%) were HIV-positive, median CD4 count 173 cells/mm³ (IQR 70-294). Fifty (86%) patients experienced ≥1 new or worsening AE after starting DLM, most commonly vomiting, QTcB >450 ms and/or myalgia. Serious and/or severe AEs were experienced by 22 (38%) patients; three HIV-positive patients died (not related to DLM). HIV status was not significantly associated with number (P = 0.089) or severity/seriousness (P = 0.11) of AEs during exposure to DLM. Two (3%) patients had DLM withdrawn due to AEs.CONCLUSION: AEs during RR-TB treatment, both before and during DLM exposure, were common, with relatively few serious/severe AEs considered related to DLM and no significant association with HIV status. Clinical and electrocardiography monitoring should be prioritised in the first two months after starting DLM.

Barriers and solutions to finding rifampicin-resistant tuberculosis cases in older children and adolescents

Little is known about the barriers to post-exposure management of rifampicin-resistant tuberculosis (RR-TB) in older children and adolescents. We report on implementation lessons from a pilot programme targeting household-exposed individuals aged 6-18 years in Khayelitsha, South Africa. Barriers included misperceptions regarding risk of exposure, multiple research and implementation stakeholders, additional workload for an overburdened healthcare system, logistical issues faced by families, and insufficient human and financial resources. Solutions to these barriers are possible, but creativity and persistence are required. Our experience can guide others looking to roll-out care for children and adolescents exposed to RR-TB.

EMERGENCE OF BEDAQUILINE RESISTANCE AFTER COMPLETION OF BEDAQUILINE-BASED DRUGRESISTANT TB TREATMENT: A CASE STUDY FROM SOUTH AFRICA

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Mass spectrometry to complement standardization of house dust mite and other complex allergenic extracts

In the United States, the Center for Biologics Evaluation and Research of the US Food and Drug Administration regulates biologics used for diagnosis and treatment of allergic diseases. The Code of Federal Regulations 21CFR680.3(e) states that when measured, the potency of an allergenic extract is assessed according to its allergenic activity. As of 2016, 19 allergenic extracts are standardized for potency in the United States. While these standardized extracts constitute a minority of those available, they treat the most prevalent allergies (e.g. grass and ragweed pollens, dust mites, and cat) and those that induce life-threatening anaphylaxis (e.g. Hymenoptera venom). Standardization for potency enhances safety and efficacy of immunotherapy by minimizing the risks of variations in allergen dosing when switching from one lot of manufactured extract to another, and by providing an objective measure of stability of each lot of allergenic extract over time. Allergenic extracts that have multiple immunodominant allergenic proteins are standardized with little or no information about compositional differences among extracts. Here, we propose application of mass spectrometry towards measurement of compositional differences among extracts that may affect the efficacy and safety of allergen immunotherapy. In addition, we discuss of house dust mite allergen extracts as a prototypical complex extract that may be standardized by mass spectrometry.

Synthesis of heteroatomic bridged paracyclophanes

Heteroatomic bridged paracyclophanes were obtained by two independent synthetic approaches. The required precursors consist of para R₂SiCl (R = Me, iPr) substituted aromatic rings (2 and 4). They were subsequently functionalised by using NH₃, [LiPH₂(dme)] or LiAl(PH₂)₄. In the case of the Me-substituted species 2, the reaction with NH₃ directly yielded the Si₂N bridged paracyclophane 5. The Si₂P incorporated derivative 10 was obtained by lithiation of p-C₆H₄(SiiPr₂PH₂)₂ (9) and subsequent salt metathesis with the chlorosilane 4. The second approach involves the use of GaEt₃ in the formation of four membered (GaPn)₂ cycles (Pn = N, P). p-[C₆H₄{SiiPr₂N(H)GaEt₂}₂]₂ (11) and p-[C₆H₄{SiiPr₂P(H)GaEt₂}₂]₂ (12) represent the first examples of stable (GaPn)₂cis isomers as the trans species did not appear in solution. Although 11 and 12 show a similar coordination pattern, they differ in the orientation of the aromatic systems: in the solid structure, 11 adopts a - for paracyclophanes so far unique - T-shape conformation of the phenyl rings, while 12 shows the predominant coplanar orientation. All cyclophanes were characterized by X-ray diffraction, elemental analysis, NMR and IR spectroscopy.

The conformational IgE epitope profile of soya bean allergen Gly m 4

BACKGROUND

Birch pollen-related soya allergy is mediated by Gly m 4. Conformational IgE epitopes of Gly m 4 are unknown.

OBJECTIVE

To identify the IgE epitope profile of Gly m 4 in subjects with birch pollen-related soya allergy utilizing an epitope library presented by Gly m 4-type model proteins.

METHODS

Sera from patients with (n = 26) and without (n = 19) allergy to soya as determined by oral provocation tests were studied. Specific IgE (Bet v 1/Gly m 4) was determined by ImmunoCAP. A library of 59 non-allergenic Gly m 4-type model proteins harbouring individual and multiple putative epitopes for IgE was tested in IgE binding assays. Primary, secondary and tertiary protein structures were assessed by mass spectrometry, circular dichroism and nuclear magnetic resonance spectroscopy.

RESULTS

All subjects were sensitized to Gly m 4 and Bet v 1. Allergen-specific serum IgE levels ranged from 0.94 to > 100 kU_A /L. The avidities of serum IgE were 5.06 ng (allergic) and 1.8 ng (tolerant) as determined by EC₅₀ for IgE binding to Gly m 4. 96% (46/48) of the protein variants bound IgE. Model proteins had Gly m 4-type conformation and individual IgE binding clustered in six major surface areas. Gly m 4-specific IgE binding could be inhibited to up to 80% by model proteins harbouring individual IgE binding sites in an epitope-wise equimolar fashion. Receiver operating curve analysis revealed an area under fitted curve of up to 0.88 for model proteins and 0.66 for Gly m 4.

CONCLUSION AND CLINICAL RELEVANCE

Serum levels and avidity of Gly m 4-specific IgE do not correlate with clinical reactivity to soya. Six IgE-binding areas, represented by 23 amino acids, account for more than 80% of total IgE binding capacity of Gly m 4. Model proteins may be used for epitope-resolved diagnosis to differentiate birch-soya allergy from clinical tolerance.

Epicutaneous immunotherapy with a hypoallergenic Bet v 1 suppresses allergic asthma in a murine model

BACKGROUND

Due to reduced allergic potency, hypoallergenic variants have been suggested as safer and potentially more efficacious alternative to the corresponding wild-type allergens in allergen-specific immunotherapy. Here, we aimed at investigating the efficacy of recombinant Bet v 1B2, a hypoallergenic folding variant of Bet v 1, in epicutaneous immunotherapy to suppress asthmatic features using a murine model of birch pollen allergy.

METHODS AND RESULTS

Before, or after sensitization with rBet v 1 plus ALUMW and intranasal challenges with birch pollen extract, BALB/c mice received epicutaneous immunization (EPI) with rBet v 1, or rBet v 1B2 on their depilated back. Prophylactic EPI with rBet v 1B2, but not with rBet v 1, suppressed serum levels of Bet v 1-specific IgE antibodies and reduced the number of eosinophils and the concentrations of Th2 cytokines in bronchoalveolar lavage. In an established allergic condition, serum levels of Bet v 1-specific IgE antibodies were similar between PBS-treated control mice and EPI-treated mice. However, therapeutic EPI with rBet v 1B2, but not with rBet v 1, significantly suppressed the development of airway inflammation and lung function impairment.

CONCLUSION

This study is the first to show the effect of therapeutic EPI with a recombinant form of a hypoallergenic folding variant on the suppression of asthmatic features. Our results suggest that rBet v 1B2 along with its reduced IgE-binding capacity could be a preferred therapeutic allergen than wild-type rBet v 1 in epicutaneous immunotherapy of birch pollen-induced allergic asthma, in particular due to a lower risk of allergic side effect.

Identification of a Dau c PRPlike protein (Dau c 1.03) as a new allergenic isoform in carrots (cultivar Rodelika)

BACKGROUND

Up to 25% of food allergic subjects in central Europe suffer from carrot allergy. Until now, two isoforms of the major carrot (Daucus carota) allergen Dau c 1 have been described: Dau c 1.01, comprising five variants (Dau c 1.0101-Dau c 1.0105) and Dau c 1.02.

OBJECTIVE

To investigate potential allergenic properties of a Dau c PRPlike protein, a novel isoform of the PR-10 protein family in carrot.

METHODS

Dau c PRPlike cDNA from carrot roots (cv Rodelika) was cloned after RT-PCR and 5'RACE. Dau c PRPlike protein was expressed in E. coli, purified under native conditions by Ni-NTA chromatography and analysed by CD spectroscopy. Immuno-reactivity of the rDau c PRPlike protein was compared with rDau c 1.0104 and rDau c 1.0201 in terms of IgE binding (immunoblotting, ImmunoCAP), IgE cross-reactivity (ELISA inhibition) and in vitro mediator release with sera from carrot allergic patients. mRNA expression of Dau c PRPlike protein in wild-type and transgenic carrot roots was analysed by qRT-PCR.

RESULTS

The Dau c PRPlike protein was identified as a new allergenic isoform, Dau c 1.03, in carrot roots. 68% of carrot allergic patients were sensitized to rDau c 1.03. The IgE-reactivity of rDau c 1.03 strongly correlated with reactivity to rDau c 1.0104, but not to rDau c 1.0201. The extent of IgE cross-reactivity and allergenic potency of Dau c 1 isoforms varied between the individual sera tested. Dau c 1.03 mRNA transcripts were up-regulated in Dau c 1.01 and Dau c 1.02 gene-silenced carrot roots.

CONCLUSION AND CLINICAL RELEVANCE

Dau c 1 isoforms display distinct IgE epitope heterogeneity. Dau c 1.03 appears to contribute to the allergenicity of carrots and the manifestation of carrot allergy. The epitope diversity of different Dau c 1 isoforms should be considered for component-resolved diagnosis and gene silencing of carrot allergens.

Kinetics of protein-release by an aptamer-based DNA nanodevice

A recently introduced DNA nanodevice can be used to selectively bind or release the protein thrombin triggered by DNA effector strands. The release process is not well described by simple first or second order reaction kinetics. Here, fluorescence resonance energy transfer and fluorescence correlation spectroscopy experiments are used to explore the kinetics of the release process in detail. To this end the influence of concentration variations and also of temperature is determined. The relevant kinetic parameters are extracted from these experiments and the kinetic behavior of the system is simulated numerically using a set of rate equations. The hydrodynamic radii of the aptamer device alone and bound to thrombin are determined as well as the dissociation constant for the aptamer device-thrombin complex. The results from the experiments and a numerical simulation support the view that the DNA effector strand first binds to the aptamer device followed by the displacement of the protein.

A critical assessment of allergen component-based in vitro diagnosis in cherry allergy across Europe

BACKGROUND

Food allergy to cherry occurs throughout Europe, typically with restricted oral reactions in the central and northern parts but with frequent systemic reactions in the Mediterranean region. Previous studies have demonstrated insufficient sensitivity of commercially available cherry extract reagents in the diagnosis of cherry allergy.

OBJECTIVE

To assess the diagnostic performance of specific IgE tests based on recombinant cherry allergens in comparison with an extract-based assay and to skin prick test (SPT). A secondary objective was to analyse the frequency of systemic reactions in cherry-allergic subjects across Europe, including the largest population of LTP-sensitized subjects from central Europe studied to date.

METHODS

A total of 186 subjects from central Europe and Spain were studied. Serum IgE was analysed with ImmunoCAP tests carrying rPru av 1, 3 and 4, combined and separately, and cherry extract.

RESULTS

Among the central European cherry allergics, the mix of rPru av 1, 3 and 4 had a sensitivity of 95%, compared with 65% for cherry extract, and the IgE binding capacity of the recombinant mix was considerably higher. The sensitivity of the two tests was more comparable in the Spanish population, 95% and 86%, respectively. The recombinant allergen ImmunoCAP equalled SPT in terms of sensitivity and specificity. Consistent with previous reports, major geographic differences in sensitization pattern and prevalence of systemic reactions were found. A significantly higher rate of systemic reactions was found in Spanish patients sensitized to Pru av 3 whereas German patients sensitized to LTP only had oral allergy syndrome.

CONCLUSIONS

The recombinant cherry allergen ImmunoCAP is a highly sensitive diagnostic tool, clearly superior to any diagnostic method based on cherry extract. Three cherry allergens are sufficient for detecting sensitization in 95% of cherry-allergic subjects. Systemic reactions are common in LTP-sensitized individuals but seem to require at least one additional causative factor.

Scaffolding microdomains and beyond: the function of reggie/flotillin proteins

Reggie/flotillin proteins are considered to be components of lipid rafts and are commonly used as marker proteins for lipid microdomains. Yet almost a decade after their discovery, the function of reggies/ flotillins is still enigmatic. In this review we summarize the present state of knowledge on reggie/flotillin structure, localization and function, and discuss the role of the proteins in development and disease. Based on insights into reggie/flotillin function and by comparison with related proteins of the so-called SPFH (Stomatin/Prohibitin/Flotillin/HflK/C) protein family, including stomatin, podocin and prohibitin, we propose the existence of specific types of protein-defined microdomains which are sculpt by the clustering of individual SPFH proteins. As 'specialized rafts' similar to caveolae, these membrane domains provide platforms for the recruitment of multiprotein complexes. Since, under certain circumstances, reggie-2/flotillin-1 translocates to the nucleus, reggie/ flotillin microdomains are not only stable scaffolds but also dynamic units with their own regulatory functions.

PrPc and reggies/flotillins are contained in and released via lipid-rich vesicles in Jurkat T cells

A new model of caveolin association with lipid body cores has recently been proposed which may be relevant to a number of cellular processes, e.g. lipid body generation. Here we show that PrPc and reggie-1 and reggie-2 also occur in the cores of Nile Red/Bodipy-stained (neutral lipid-containing) vesicular structures and, in immunoblots, in the lipid-enriched fraction after density gradient centrifugation. These lipid-rich vesicles increase in number following cell feeding with oleic acid, differ from early endosome antigen 1- and Lamp-2-positive endosomes/lysosomes, exhibit an opaque content and lack surrounding actin staining. Our results suggest that the content of these vesicles, together with reggie-1 and -2 and PrPc, is expelled.

Reduced reactivation rate in mutant CuZnSOD and progression rate of amyotrophic lateral sclerosis

Mutations in the SOD1 gene are associated with familial amyotrophic lateral sclerosis (fALS). The mechanisms by which these mutations lead to anterior horn cell loss are unknown, however, increased binding of Hsps on the demetallated mutant SOD1 has been described which would make the HSPs unavailable for other purposes, and reduce the SOD1 concentration in mitochondria, thereby creating a proapoptotic situation finally leading to motor neuron death. Here we report the recombinant expression of four human copper/zinc superoxide dismutase (CuZnSOD) variants, including the wild-type enzyme and mutant proteins associated with familial ALS. The bacterial expression level of soluble mutated proteins was influenced by the mutations leading to drastically reduced levels of soluble CuZnSOD. Simultaneously, increasing levels of insoluble and probably aggregated mutated CuZnSOD were identified in bacterial cell pellets. In addition, altered reactivation kinetics of the purified mutant apoproteins after expression in bacterial culture was shown. Biophysical and biochemical analysis showed that zinc incorporation is severely reduced in the CuZnSOD proteins associated with the most severely forms of fALS (A4V, G93A). These data indicate that a reduced holoenzyme formation rate of mutant enzymes may be a critical factor in the etiopathology of fALS.

Therapeutic vaccine for acute and chronic motor neuron diseases: implications for amyotrophic lateral sclerosis

Therapeutic vaccination with Copaxone (glatiramer acetate, Cop-1) protects motor neurons against acute and chronic degenerative conditions. In acute degeneration after facial nerve axotomy, the number of surviving motor neurons was almost two times higher in Cop-1-vaccinated mice than in nonvaccinated mice, or in mice injected with PBS emulsified in complete Freund's adjuvant (P < 0.05). In mice that express the mutant human gene Cu/Zn superoxide dismutase G93A (SOD1), and therefore simulate the chronic human motor neuron disease amyotrophic lateral sclerosis, Cop-1 vaccination prolonged life span compared to untreated matched controls, from 211 +/- 7 days (n = 15) to 263 +/- 8 days (n = 14; P < 0.0001). Our studies show that vaccination significantly improved motor activity. In line with the experimentally based concept of protective autoimmunity, these findings suggest that Cop-1 vaccination boosts the local immune response needed to combat destructive self-compounds associated with motor neuron death. Its differential action in CNS autoimmune diseases and neurodegenerative disorders, depending on the regimen used, allows its use as a therapy for either condition. Daily administration of Cop-1 is an approved treatment for multiple sclerosis. The protocol for non-autoimmune neurodegenerative diseases such as amyotrophic lateral sclerosis, remains to be established by future studies.

A novel calcineurin splice variant that modifies calcineurin activity

Calcineurin is a Ca(2+)/calmodulin dependent phosphoprotein phosphatase implicated in a wide range of disorders. Here, we report the cloning of a novel calcineurin A alpha splice variant that lacks both the catalytic and calcineurin B binding domains. Biochemical analysis revealed a stimulating effect on calcineurin activity at low calcium concentrations as well as protein-protein interaction with the catalytic calcineurin holoenzyme. By Western blot analysis, expression of similar short splice variants could be seen in the spinal cord of an animal model of familial amyotrophic lateral sclerosis, suggesting a role of these new variants in motor neuron disease.

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The first part of this thesis deals with treatment in the early stages. Splints were an essential means of treatment. An after-treatment became imperative depending on the success of the bone and soft tissue plastic. Alexander von Postas thesis on after-treatment has been studied in more detail. It describes surgical and alternative methods. Orthodontic appliances such as inclined planes, sliding splint, elastics or the frame splint were used. The second section of this thesis is concerned with specific methods of after-treatment. These include the treatment of scars by excision, softening, massage, suction, hot air or chemical substances. Further, the treatment of lock-jaw or TMJ-ankylosis, pseudoarthrosis and nerve-injuries. The last section of this thesis briefly touches upon possible therapies of speech defects.

Superoxide dismutase mutations of familial amyotrophic lateral sclerosis and the oxidative inactivation of calcineurin

Approximately 10% of all familial cases of amyotrophic lateral sclerosis (fALS) are linked to mutations in the SOD1 gene, which encodes the copper/zinc superoxide dismutase (CuZnSOD). Recently, wild-type CuZnSOD was shown to protect calcineurin, a calcium/calmodulin-regulated phosphoprotein phosphatase, from inactivation by reactive oxygen species. We asked whether the protective effect of CuZnSOD on calcineurin is affected by mutations associated with fALS. For this, we monitored calcineurin activity in the presence of mutant and wild-type SOD. We found that the degree of protection against inactivation of calcineurin by different SOD mutants correlates with the severity of the phenotype associated with the different mutations, suggesting a potential role for calcineurin-SOD1 interaction in the etiology of fALS.

Enhanced gamma-glutamyl transpeptidase expression and superoxide production in Mpv17-/- glomerulosclerosis mice

Recently, gamma-glutamyl transpeptidase, which initiates cleavage of extracellular glutathione, has been shown to promote oxidative damage to cells. Here we examined a murine disease model of glomerulosclerosis, involving loss of the Mpv17 gene coding for a peroxisomal protein. In Mpv17-/- cells, enzyme activity and mRNA expression (examined by quantitative RT-PCR) of membrane-bound gamma-glutamyl transpeptidase were increased, while plasma glutathione peroxidase and superoxide dismutase levels were lowered. Superoxide anion production in these cells was increased as documented by electron spin resonance spectroscopy. In the presence of Mn(III)tetrakis(4-benzoic acid)porphyrin, the activities of gamma-glutamyl transpeptidase and plasma glutathione peroxidase were unchanged, suggesting a relationship between enzyme expression and the amount of reactive oxygen species. Inhibition of gamma-glutamyl transpeptidase by acivicin reverted the lowered plasma glutathione peroxidase and superoxide dismutase activities, indicating reciprocal control of gene expression for these enzymes.

Ultrastructural and physiological defects in the cochlea of the Mpv17 mouse strain

Ultrastructural investigations were performed in young (approximately 2 months) and old (7 months) Mpv17-negative and wild-type mice. The onset, the severity and the pattern of the degeneration significantly differed between both mice strains. In the wild-type mouse strain the degenerative changes of the cochlear structures were similar to the aging pattern described for other species. In contrast, the Mpv17 mutants showed degenerative changes of the cochlear structures already at the age of 2 months. The degenerative changes were patchy arranged throughout the entire length of the cochlea and involved the organ of Corti as well as the stria vascularis epithelia with alterations of the basement membrane of the capillaries. The severe sensorineural hearing loss and degenerative changes of the cochlear structures indicate that cochlear structures, especially the outer hair cells and the intermediate cells of the stria vascularis, are vulnerable to the missing Mpv17 gene product.

Calcineurin A and calbindin immunoreactivity in the spinal cord of G93A superoxide dismutase transgenic mice

A qualitative immunohistochemical study was performed on calcineurin A- and calbindin-positive neurons in the spinal cord of transgenic mice, an animal model of amyotrophic lateral sclerosis, carrying the G93A mutation of the Cu/Zn-superoxide dismutase gene. The results show that calcineurin A-immunoreactive motoneurons are affected by the neurodegenerative process; in contrast, calbindin-positive cells are selectively spared. The findings suggest that calcineurin plays a role as an accessory factor responsible for selective vulnerability in the neurodegenerative process of amyotrophic lateral sclerosis.

Age-dependent hypertension in Mpv17-deficient mice, a transgenic model of glomerulosclerosis and inner ear disease

The mutant mouse strain Mpv17-/-, carries a retroviral germline integration that inactivates the Mpv17 gene. Mpv17-deficient mice develop progressive glomerulosclerosis and sensineural deafness at early age. Characteristic basement membrane alterations are found in both sites of pathology. Mpv17 is a peroxisomal protein involved in the metabolism of reactive oxygen species, yet its molecular function is unknown. Dysregulation of antioxidant enzymes and basal membrane components has been established in this model and successful therapeutic intervention with antioxidants prove the causal role of reactive oxygen species in the development of the disease phenotype. We here investigated if the Mpv17-/- mice might be hypertensive. Indeed, our study revealed that Mpv17-/- mice developed significant systemic hypertension and tachycardia between 4 weeks and 5 months of age, accompanied by polyuria and elevated natriuresis. Judging from serum and urine parameters, the hypertensive condition develops concomitantly with the renal disease. Biochemical and pharmacological studies that used the endothelin receptor antagonist bosentan and the angiotensin converting enzyme inhibitor cilazapril indicated no involvement of the endothelin and renin-angiotensin systems in this hypertension, suggesting a potential novel mechanism of blood pressure regulation in this new murine hypertension model. Thus, Mpv17-/- mice unravel an intriguing new association between a defect in reactive oxygen metabolism and the age-dependent development of hypertension.

Expression of the recessive glomerulosclerosis gene Mpv17 regulates MMP-2 expression in fibroblasts, the kidney, and the inner ear of mice

The recessive mouse mutant Mpv17 is characterized by the development of early-onset glomerulosclerosis, concomitant hypertension, and structural alterations of the inner ear. The primary cause of the disease is the loss of function of the Mpv17 protein, a peroxisomal gene product involved in reactive oxygen metabolism. In our search of a common mediator exerting effects on several aspects of the phenotype, we discovered that the absence of the Mpv17 gene product causes a strong increase in matrix metalloproteinase 2 (MMP-2) expression. This was seen in the kidney and cochlea of Mpv17-negative mice as well as in tissue culture cells derived from these animals. When these cells were transfected with the human Mpv17 homolog, an inverse causal relationship between Mpv17 and MMP-2 expression was established. These results indicate that the Mpv17 protein plays a crucial role in the regulation of MMP-2 and suggest that enhanced MMP-2 expression might mediate the mechanisms leading to glomerulosclerosis, inner ear disease, and hypertension in this model.

Intra-abdominal lymphangioma in a newborn

We report the case of a male newborn infant with an intra-abdominal cavernous lymphangioma that produced acute abdominal symptoms. Sonography showed a cystic mass with thin septations, which caused intestinal obstruction and stenosis of the iliac artery. The histologic findings after surgical resection reflected the sonographic appearance of the mass. The differential diagnosis of cystic abdominal lesions is discussed. Sonography is the preferred method of diagnosis.

Loss of auditory function in transgenic Mpv17-deficient mice

The transgenic mouse strain Mpv17 develops severe morphological degeneration of the inner ear and nephrotic syndrome at a young age (Meyer zum Gottesberge et al., 1996; Weiher et al., 1990). The audiograms (1-32 kHz) of Mpv17-negative mice were determined from auditory brain stem responses in young (2 months) and old (7 months) animals. Audiograms of age-matched wild-type mice with the same genetic background, but wild-type at the Mpv17 locus, were also determined. Furthermore, young Mpv17-negative mice that carried a human Mpv17 homologue gene were studied. NMRI mice served as a reference for normal hearing. Mpv17-negative mice suffer from severe sensorineural hearing loss as early as 2 months after birth. In the old Mpv17-negative mice no responses could be elicited at all. The 2 month old wild-type mice had normal audiograms, at 7 months only high threshold responses were seen. The poor audiograms of the Mpv17-negative mice are assumed to be the functional correlate of the morphological degeneration of the cochlea described earlier (Meyer zum Gottesberge et al., 1996). The finding that 2 out of 4 Mpv17-negative mice with the human Mpv17 gene had normal audiograms, shows that the gene inactivation can be functionally compensated by the human Mpv17 gene product.

Inner ear defect similar to Alport's syndrome in the glomerulosclerosis mouse model Mpv17

The Mpv17 mouse strain is a recessive transgenic mouse mutant that develops glomerulosclerosis and nephrotic syndrome at a young age. The phenotype results from a loss of function of a gene coding for a hydrophobic peroxisomal protein of 176 amino acids of 20 kDa following its destruction by retroviral integration. To investigate a potential effect of the missing Mpv17 function on the inner ear light and electron microscopic investigations were performed on the inner ears of Mpv17 mice and controls. These revealed degeneration of the stria vascularis and spiral ligament, loss of cochlear neurons and degeneration of the organ of Corti. The alterations observed here were similar to those described for Alport's syndrome, an inherited disorder characterized by progressive nephritis and neurosensory deafness. These findings indicate that although the molecular cause is different, the Mpv17 mouse model may share pathological mechanisms involved in patients with Alport's syndrome. At present the Mpv17 mouse appears to be a suitable animal model for this disease and may help to further elucidate the relationship between the kidney and the inner ear.

Functional rescue of the glomerulosclerosis phenotype in Mpv17 mice by transgenesis with the human Mpv17 homologue

The germ line insertion of a defective retrovirus into the Mpv17 gene of mice is associated with a recessive phenotype. Mice homozygous for the integration develop glomerulosclerosis at a young age. The phenotype resembles human glomerulosclerosis in its physiological parameters as well as in histology. A human homologue of the Mpv17 gene has been identified, isolated and analyzed. We here show that this gene, which has a role in the production of reactive oxygen species, can rescue the phenotype of Mpv17 deficient mice when introduced by transgenesis. This provides formal proof for the hypothesis that the phenotype is caused by the loss of function of the Mpv17 gene. It also provides evidence for the functional conservation of the Mpv17 gene in mammals and points to a potential role of this gene in human kidney disease.

The glomerulosclerosis gene Mpv17 encodes a peroxisomal protein producing reactive oxygen species

The mutant mouse strain Mpv17 carries a retroviral insert in its genome which inactivates the Mpv17 gene. At a young age these mice develop glomerulosclerosis and nephrotic syndrome which resembles human disease. We show here that the Mpv17 gene product is highly conserved and encodes a peroxisomal protein. Loss of the Mpv17 protein does not impair peroxisome biogenesis but instead leads to a reduced ability to produce reactive oxygen species (ROS). In turn, overproduction of the Mpv17 gene in transfected cells results in dramatically enhanced levels of intracellular ROS indicating a direct involvement of Mpv17 in ROS production. These data reveal a role for the Mpv17 protein in peroxisomal reactive oxygen metabolism and establish a novel link between peroxisomal ROS production and glomerulosclerosis.

The human homolog of the glomerulosclerosis gene Mpv17: structure and genomic organization

Mice carrying a retroviral insert in both alleles of the Mpv17 gene develop glomerulosclerosis and nephrotic syndrome at young age. Thus, the Mpv17 gene is a recessive disease gene in mice and this mouse strain is a potential animal model for glomerular diseases in man. We here describe the isolation and analysis of a human homolog of this gene. By interspecies hybridisation cDNA clones representing a single RNA species were isolated from human liver. Sequence analysis revealed over 90% identify in a region coding for a protein of 176 amino acids and unknown function in both species. Cloning of the genomic locus revealed a single copy gene which we mapped to the short arm of chromosome 2 at band 2p23-p21. Determination of the intron-exon structure and the junction sequences enabled us to establish a PCR based procedure to isolate the coding region from human genomic DNA. Thus, it is now possible to analyse patients suffering from candidate diseases on the basis of a blood sample if biopsy material is not available.