The use of 68Ga-EDTA PET allows detecting progressive decline of renal function in rats

INTRODUCTION

Evaluation of glomerular filtration rate is very important in both preclinical and clinical setting, especially in the context of chronic kidney disease. It is typically performed using ⁵¹Cr-EDTA or by imaging with ¹²³I-Hippuran scintigraphy, which has a significantly lower resolution and sensitivity as compared to PET. ⁶⁸Ga-EDTA represents a valid alternative due to its quick availability using a ⁶⁸Ge/⁶⁸Ga generator, while PET/CT enables both imaging of renal function and accurate quantitation of clearance of activity from both plasma and urine. Therefore, we aimed at investigating the use of ⁶⁸Ga-EDTA as a preclinical tracer for determining renal function in a knock-in rat model known to present progressive decline of renal function.

METHODS

⁶⁸Ga-EDTA was injected in 23 rats, either wild type (n=10) or knock-in (n=13). By applying a unidirectional, two-compartment model and Rutland-Patlak Plot linear regression analysis, split renal function was determined from the age of 6 weeks to 12 months.

RESULTS

Glomerular filtration ranged from 0.025±0.01 ml/min at 6 weeks to 0.049±0.05 ml/min at 6 months in wild type rats. Glomerular filtration was significantly lower in knock-in rats at 6 and 12 months (P<0.01). No significant difference was observed in renal volumes between knock-in and wild type animals, based on imaging-derived volume calculations.

CONCLUSIONS

⁶⁸Ga-EDTA turned out to be a very promising PET/CT tracer for the evaluation of split renal function. This method allowed detection of progressive renal impairment in a knock-in rat model. Additional validation in a human cohort is warranted to further assess clinical utility in both, healthy individuals and patients with renal impairment.

A knock-in rat model unravels acute and chronic renal toxicity in glutaric aciduria type I

Glutaric aciduria type I (GA-I, OMIM # 231670) is an autosomal recessive inborn error of metabolism caused by deficiency of the mitochondrial enzyme glutaryl-CoA dehydrogenase (GCDH). The principal clinical manifestation in GA-I patients is striatal injury most often triggered by catabolic stress. Early diagnosis by newborn screening programs improved survival and reduced striatal damage in GA-I patients. However, the clinical phenotype is still evolving in the aging patient population. Evaluation of long-term outcome in GA-I patients recently identified glomerular filtration rate (GFR) decline with increasing age. We recently created the first knock-in rat model for GA-I harboring the mutation p.R411W (c.1231 C>T), corresponding to the most frequent GCDH human mutation p.R402W. In this study, we evaluated the effect of an acute metabolic stress in form of high lysine diet (HLD) on young Gcdh^ki/ki rats. We further studied the chronic effect of GCDH deficiency on kidney function in a longitudinal study on a cohort of Gcdh^ki/ki rats by repetitive ⁶⁸Ga-EDTA positron emission tomography (PET) renography, biochemical and histological analyses. In young Gcdh^ki/ki rats exposed to HLD, we observed a GFR decline and biochemical signs of a tubulopathy. Histological analyses revealed lipophilic vacuoles, thinning of apical brush border membranes and increased numbers of mitochondria in proximal tubular (PT) cells. HLD also altered OXPHOS activities and proteome in kidneys of Gcdh^ki/ki rats. In the longitudinal cohort, we showed a progressive GFR decline in Gcdh^ki/ki rats starting at young adult age and a decline of renal clearance. Histopathological analyses in aged Gcdh^ki/ki rats revealed tubular dilatation, protein accumulation in PT cells and mononuclear infiltrations. These observations confirm that GA-I leads to acute and chronic renal damage. This raises questions on indication for follow-up on kidney function in GA-I patients and possible therapeutic interventions to avoid renal damage.

P899Long-term evolution of Fabry cardiomyopathy under enzyme replacement therapy in the Swiss Fabry cohort. An echocardiographic study

Introduction

Fabry cardiomyopathy may present with left ventricular hypertrophy (LVH) and enzyme replacement therapy (ERT) aims to slow its progression in affected patients. LVH progression may be observed despite ERT and the aim of this study was to identify predictors of adverse LV remodeling under treatment.

Methods

This multicentric study included consecutive Fabry patients receiving ERT and for whom a clinical follow-up (FU) with echocardiography (TTE) of at least 5 years was available. The first TTE was performed at the time of ERT start and disease progression was defined as an increase in LV mass index between the first and the last available FU TTE.

Results

Sixty-one patients (median age 35 years [23–48] and 40 (66%) men) were included with a median FU of 10.5 years [7.2–12.2]. Progression was seen in 33 (54%) patients with an annual increase in LV mass index of 1.8 g/m2/year [0.7–3.2] (vs −0.8 g/m2/year [−1.6 to 0.4] in the non-progression group). Presence of LVH (>95 g/m2 in women or >115 g/m2 in men) at the start of ERT was the only morphological baseline parameter significantly associated with progression after adjustment for age, gender and baseline arterial hypertension (OR 22.5, 95% CI 2.7–188.3, p=0.004). Over the FU duration, patients with baseline LVH (n=22) had higher increase in LV diastolic diameter (2.3±4.9 mm vs 0.9±4.1, p=0.009), a lower increase in relative wall thickness (−1.7±14.1% vs 4.6±9.8%, p=0.04), and a higher increase in LV mass index (22±22 g/m2 vs 0±17 g/m2, p=0.001), as compared with patients with no baseline LVH. While no difference was seen in the evolution of the LV ejection fraction, a faster decline in diastolic function was observed in patients with baseline LVH, with a higher increase in E/e' ratio (5.9±7.4 vs 1.1±2.8, p=0.001) and in left atrial diameter (4.7±5.4 mm vs 1.8±5.2 mm).

Baseline characteristics All (n=61) No LVH (n=39) LVH (n=22) p Age (years) 35 [23–48] 17 [21–36] 50 [44–54] <0.001 Male gender 40 (66%) 22 (56%) 18 (82%) 0.79 Arterial hypertension 10 (17%) 3 (8%) 7 (31%) 0.03 LV mass index (g/m2) 105±43 79±18 150±38 <0.001 Mitral E/e' ratio 7.8±5.0 6.7±2.0 9.9±7.8 0.02

Conclusion

Over a median FU of over 10 years, LV wall thickness, LV mass and LV diastolic function remained stable under ERT, providing the treatment was started, early, i.e. before development of LVH. If LVH is already present at baseline, ERT appears to be less effective, with significant progression in LV mass and significantly faster decrease in diastolic function.

Long-term follow-up of pulmonary function in Fabry disease: A bi-center observational study

INTRODUCTION

Fabry disease (FD) is a lysosomal storage disorder leading to decreased α-galactosidase A enzyme activity and subsequent abnormal accumulation of glycosphingolipids in various organs. Although histological evidence of lung involvement has been demonstrated, the functional impact of these changes is less clear.

MATERIALS AND METHODS

Adult patients with FD who had yearly pulmonary function tests (PFT) at two centers from 1999 thru 2015 were eligible for this observational study. Primary outcome measures were the change in forced expiratory volume in the first second (FEV1) and FEV1/FVC over time. As secondary outcome we investigated sex, smoking, enzyme replacement therapy (ERT), residual enzyme activity, and Mainz Severity Score Index as possible predictors.

RESULTS

95 patients (41% male, 38.2 ± 14.5 years) were included. The overall prevalence of bronchial obstruction (BO, (FEV1/FVC < 70%)) was 46%, with male sex, age and smoking as significant predictors. FEV1 decreased 29 ml per year (95% CI -36, -22 ml, p<0.0001). FEV1 decline was significantly higher in males (p = 0.009) and in patients on ERT (p = 0.004). Conclusion: Pulmonary involvement seems to be a relevant manifestation of Fabry disease, and routine PFTs should therefore be included in the multidisciplinary follow-up of these patients.

Clinical and molecular characterization of cystinuria in a French cohort: relevance of assessing large-scale rearrangements and splicing variants

Background

Cystinuria is an autosomal recessive disorder of dibasic amino acid transport in the kidney and the intestine leading to increased urinary cystine excretion and nephrolithiasis. Two genes, SLC3A1 and SLC7A9, coding respectively for rBAT and b0,+AT, account for the genetic basis of cystinuria.

Methods

This study reports the clinical and molecular characterization of a French cohort including 112 cystinuria patients and 25 relatives from 99 families. Molecular screening was performed using sequencing and Quantitative Multiplex PCR of Short Fluorescent Fragments analyses. Functional minigene‐based assays have been used to characterize splicing variants.

Results

Eighty‐eight pathogenic nucleotide changes were identified in SLC3A1 (63) and SLC7A9 (25) genes, of which 42 were novel. Interestingly, 17% (15/88) and 11% (10/88) of the total number of variants correspond, respectively, to large‐scale rearrangements and splicing mutations. Functional minigene‐based assays were performed for six variants located outside the most conserved sequences of the splice sites; three variants affect splice sites, while three others modify exonic splicing regulatory elements (ESR), in good agreement with a new in silico prediction based on ΔtESRseq values.

Conclusion

This report expands the spectrum of SLC3A1 and SLC7A9 variants and supports that digenic inheritance is unlikely. Furthermore, it highlights the relevance of assessing large‐scale rearrangements and splicing mutations to fully characterize cystinuria patients at the molecular level.

Pulmonary Involvement in Adult Patients with Inborn Errors of Metabolism

Inborn errors of metabolism (IEM) are rare individually, but taken together, they affect 1 in 1,000 people. Most of the disease becomes apparent at the pediatric age; however, with the identification of late-onset forms, and with improved survival, several of these conditions may be found in adults of all ages. While the lung is not typically a primary site of clinical disease in patients with IEM, in some of them it can be a significantly affected organ with associated severe respiratory complications. Lung involvement can be a late- onset feature of a complex multisystemic disease, but sometimes it can also be the only manifestation of underlying IEM. The aim of this review is to focus on specific IEM associated with lung disease in adults and to provide the reader with an overview of the diagnostic workup, overall disease management, and specific treatments for the respiratory manifestations. Clinical suspicion, early recognition, prompt diagnosis, and appropriate care of the respiratory manifestation are crucial, as they can affect both the life expectancy and the quality of life of these patients.

[Raising the internist's know-how in the field of rare diseases: mitochondrial diseases as an illustrative example]

Rare Diseases, defined by a prevalence of less than 1 per 2000 persons, affect 36 million people in Europe, 500 000 in Switzerland, corresponding to 6-8% of the general population. 7000 rare diseases are currently recorded.Mitochondrial diseases are a heterogeneous group of genetic diseases. They are characterized by intracellular failure of energy production and affect predominantly energy-dependent tissues. The clinical presentation is not always suggestive, particularly in adulthood. In order to reach the diagnosis, a prerequisite is to think of them. In this article, we will focus on the clinical aspects of mitochondrial disorders in order to give the internist simple tools on how not to miss those rare diseases in his daily practice.

A novel mutation in BCS1L associated with deafness, tubulopathy, growth retardation and microcephaly

We report a novel homozygous missense mutation in the ubiquinol-cytochrome c reductase synthesis-like (BCS1L) gene in two consanguineous Turkish families associated with deafness, Fanconi syndrome (tubulopathy), microcephaly, mental and growth retardation. All three patients presented with transitory metabolic acidosis in the neonatal period and development of persistent renal de Toni-Debré-Fanconi-type tubulopathy, with subsequent rachitis, short stature, microcephaly, sensorineural hearing impairment, mild mental retardation and liver dysfunction. The novel missense mutation c.142A>G (p.M48V) in BCS1L is located at a highly conserved region associated with sorting to the mitochondria. Biochemical analysis revealed an isolated complex III deficiency in skeletal muscle not detected in fibroblasts. Native polyacrylamide gel electrophoresis (PAGE) revealed normal super complex formation, but a shift in mobility of complex III most likely caused by the absence of the BCS1L-mediated insertion of Rieske Fe/S protein into complex III. These findings expand the phenotypic spectrum of BCS1L mutations, highlight the importance of biochemical analysis of different primary affected tissue and underline that neonatal lactic acidosis with multi-organ involvement may resolve after the newborn period with a relatively spared neurological outcome and survival into adulthood.

CONCLUSION

Mutation screening for BCS1L should be considered in the differential diagnosis of severe (proximal) tubulopathy in the newborn period.

WHAT IS KNOWN

• Mutations in BCS1L cause mitochondrial complex III deficiencies. • Phenotypic presentations of defective BCS1L range from Bjornstad to neonatal GRACILE syndrome. What is New: • Description of a novel homozygous mutation in BCS1L with transient neonatal acidosis and persistent de Toni-Debré-Fanconi-type tubulopathy. • The long survival of patients with phenotypic presentation of severe complex III deficiency is uncommon.

Recommendations for initiation and cessation of enzyme replacement therapy in patients with Fabry disease: the European Fabry Working Group consensus document

INTRODUCTION

Fabry disease (FD) is a lysosomal storage disorder resulting in progressive nervous system, kidney and heart disease. Enzyme replacement therapy (ERT) may halt or attenuate disease progression. Since administration is burdensome and expensive, appropriate use is mandatory. We aimed to define European consensus recommendations for the initiation and cessation of ERT in patients with FD.

METHODS

A Delphi procedure was conducted with an online survey (n = 28) and a meeting (n = 15). Patient organization representatives were present at the meeting to give their views. Recommendations were accepted with ≥75% agreement and no disagreement.

RESULTS

For classically affected males, consensus was achieved that ERT is recommended as soon as there are early clinical signs of kidney, heart or brain involvement, but may be considered in patients of ≥16 years in the absence of clinical signs or symptoms of organ involvement. Classically affected females and males with non-classical FD should be treated as soon as there are early clinical signs of kidney, heart or brain involvement, while treatment may be considered in females with non-classical FD with early clinical signs that are considered to be due to FD. Consensus was achieved that treatment should not be withheld from patients with severe renal insufficiency (GFR < 45 ml/min/1.73 m(2)) and from those on dialysis or with cognitive decline, but carefully considered on an individual basis. Stopping ERT may be considered in patients with end stage FD or other co-morbidities, leading to a life expectancy of <1 year. In those with cognitive decline of any cause, or lack of response for 1 year when the sole indication for ERT is neuropathic pain, stopping ERT may be considered. Also, in patients with end stage renal disease, without an option for renal transplantation, in combination with advanced heart failure (NYHA class IV), cessation of ERT should be considered. ERT in patients who are non-compliant or fail to attend regularly at visits should be stopped.

CONCLUSION

The recommendations can be used as a benchmark for initiation and cessation of ERT, although final decisions should be made on an individual basis. Future collaborative efforts are needed for optimization of these recommendations.

[Inborn errors of metabolism: transition from childhood to adulthood]

Inborn errors of metabolism (IEM) are due to mutations of genes coding for enzymes of intermediary metabolism and are classified into 3 broad categories: 1) intoxication, 2) energy defect and 3) cellular organelles synthesis or catabolism defect. Improvements of therapy over these last 20 years has improved prognosis of children with IEM. These children grow up and should have their transition to specialized adult care. Adult patients with IEM are a relatively new phenomenon with currently only limited knowledge. Extrapolated pediatric guidelines are applied to the adult population taking into account adult life stages (social independence, pregnancy, aging process and potential long-term complications).

Pulmonary involvement in Fabry disease: overview and perspectives

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by deficiency of alpha-galactosidase A, which leads to storage of sphingolipids in virtually all human cells and consequently to organ dysfunction. Pulmonary involvement is still debated. But, obstructive lung disease is up to ten times more prevalent in patients with FD compared to general public. Also, an accelerated decline in forced expiratory volume in one second (FEV1) over time was observed in these patients. Lysosomal storage of glycosphingolipids is considered leading to small airway disease via hyperplasia of the bronchiolar smooth muscle cells. Larger airways may become involved with ongoing disease process. There is no evidence for involvement of the lung interstitium in FD. The effect of enzyme replacement therapy on respiratory involvement remains to be determined in large, prospective controlled trials.

[Renal glucosuria]

The occurrence of glucosuria in the absence of hyperglycemia is distinctive for renal glucosuria. SGLT2 mutations provoke familial renal glucosuria characterized by persistent glucosuria in the absence of any other renal tubular dysfunction. Renal glucosuria associated with others proximal tubular dysfunctions points to Fanconi syndrome. This generalized dysfunction of proximal tubule needs to be treated and may progress regarding its aetiology to chronic renal failure. The development and study of models of Fanconi syndrome has recently contributed to a better knowledge of the mechanisms implicated in the tubular transport of glucose and low-molecular-weight-proteins. This article reviews these recent developments.

Enzyme replacement therapy with agalsidase alfa in patients with Fabry's disease: an analysis of registry data

BACKGROUND

We analysed 5-year treatment with agalsidase alfa enzyme replacement therapy in patients with Fabry's disease who were enrolled in the Fabry Outcome Survey observational database (FOS).

METHODS

Baseline and 5-year data were available for up to 181 adults (126 men) in FOS. Serial data for cardiac mass and function, renal function, pain, and quality of life were assessed. Safety and sensitivity analyses were done in patients with baseline and at least one relevant follow-up measurement during the 5 years (n=555 and n=475, respectively).

FINDINGS

In patients with baseline cardiac hypertrophy, treatment resulted in a sustained reduction in left ventricular mass (LVM) index after 5 years (from 71.4 [SD 22.5] g/m(2.7) to 64.1 [18.7] g/m(2.7), p=0.0111) and a significant increase in midwall fractional shortening (MFS) from 14.3% (2.3) to 16.0% (3.8) after 3 years (p=0.02). In patients without baseline hypertrophy, LVM index and MFS remained stable. Mean yearly fall in estimated glomerular filtration rate versus baseline after 5 years of enzyme replacement therapy was -3.17 mL/min per 1.73 m(2) for men and -0.89 mL/min per 1.73 m(2) for women. Average pain, measured by Brief Pain Inventory score, improved significantly, from 3.7 (2.3) at baseline to 2.5 (2.4) after 5 years (p=0.0023). Quality of life, measured by deviation scores from normal EuroQol values, improved significantly, from -0.24 (0.3) at baseline to -0.17 (0.3) after 5 years (p=0.0483). Findings were confirmed by sensitivity analysis. No unexpected safety concerns were identified.

INTERPRETATION

By comparison with historical natural history data for patients with Fabry's disease who were not treated with enzyme replacement therapy, long-term treatment with agalsidase alfa leads to substantial and sustained clinical benefits.

FUNDING

Shire Human Genetic Therapies AB.

Clinical results of enzyme replacement therapy in Fabry disease: a comprehensive review of literature

Enzyme replacement therapy (ERT) has been used to treat Fabry disease - a progressive lysosomal storage disorder - since 2001. Two preparations of the enzyme alpha-galactosidase A are available in Europe: agalsidase alpha, produced in a human cell line, and agalsidase beta, produced in Chinese hamster ovary cells. To review critically the published evidence for the clinical efficacy of these two enzyme preparations. A systematic literature search was undertaken to identify open or randomised controlled trials published on Fabry disease since 2001. Eleven trials fulfilled the criteria for inclusion in this review, of a total of 586 references on Fabry disease. To date, no direct comparisons exists between the two available enzyme preparations. Significant clinical benefits compared with placebo, however, have been demonstrated with ERT, with positive effects on the heart, kidneys, nervous system and quality of life. The quality of most of these publications was less than optimal. Further prospective studies are required to confirm the long-term clinical benefits of ERT. More studies are also needed on the effects of ERT in women and on the use of ERT early in the course of Fabry disease, to prevent organ damage. Large national and international outcomes databases will also be invaluable in evaluating treatment effects and safety.

Hyperhidrosis: a new and often early symptom in Fabry disease. International experience and data from the Fabry Outcome Survey

Hypohidrosis is a classic feature of Fabry disease; in contrast, hyperhidrosis has only been rarely described. The aim of the study is to characterise the baseline descriptive data on hyperhidrosis (frequency, age at onset, sex ratio and outcome with and without enzyme replacement therapy) in hemizygous male and heterozygous female patients with Fabry disease. We describe case histories of five patients with Fabry disease and hyperhidrosis seen at three different centres. We have also analysed a cohort of 21 paediatric patients in the UK and a large European cohort of patients enrolled in the Fabry Outcome Survey (FOS). Five patients (three female, two male) with hyperhidrosis were originally identified, although each had additional symptoms related to Fabry disease. The age at onset of hyperhidrosis was less than 18 years in four cases. In the cohort of 21 paediatric patients (12 female, nine male), one female had hyperhidrosis; the age at onset of this symptom was 11 years. In the FOS cohort, 66 of 714 patients with Fabry disease had hyperhidrosis (44 of 369 females, 11.9%; 22 of 345 males, 6.4%). The female predominance was observed in seven of nine countries from which data were analysed. Hyperhidrosis is an increasingly recognised feature of the Fabry disease phenotype. It is more prevalent in females than in males and often appears in childhood or adolescence. The efficacy of enzyme replacement therapy on this recently recognised symptom should be assessed.

[Clinical and genetics aspects of Alport syndrome]

Microscopic haematuria of glomerular origin, without known aetiology, should raise the suspicion of Alport Syndrome IASI in children as well as in adults. The genetic mutations causing AS lie in the genes encoding for the alpha3, alpha4 and alpha5 chains of the collagen type IV, the main constituent of glomerular basement membranes (GBM). The various mutations and modes of transmission of the disease account for the heterogeneous clinical presentations. No specific treatment of AS is currently available. However, a better understanding of the GBM's ultrastructure, in particular of type IV collagen, will hopefully enable the identification of novel therapeutic targets.

[Diagnosis of renal cysts]

Evaluation and management of renal cysts Renal cystic diseases are a heterogeneous group of conditions including heritable, developmental, and acquired disorders. They are united by the presence of microscopic or giant fluid-filled cavities and affect both children and adults. The definitive diagnosis of many of the renal cystic diseases requires clinical, radiological, pathological, and genetic analysis. A precise diagnosis is essential for prognosis, treatment, and future genetic counselling.

Efficacy of Enzyme Replacement Therapy in Fabry Disease

Enzyme replacement therapy has recently been introduced to treat Fabry disease, a rare X-linked lysosomal storage disorder. The disease occurs due to deficient activity of alpha-galactosidase A, leading to progressive accumulation of globotriaosylceramide in multiple organs and tissues. Renal, cardiac and cerebrovascular manifestations of the disease result in premature death in both hemizygous males and heterozygous females. This paper outlines the clinical signs, symptoms and diagnosis of Fabry disease, and the development of the two available enzyme replacement therapies -- agalsidase alfa and agalsidase beta. Agalsidase alfa and agalsidase beta are produced in a human cell line and in Chinese hamster ovary cells, respectively, resulting in products with the same amino acid sequence as the native human enzyme, but with different patterns of glycosylation. Correct post-translational glycosylation is important in terms of the pharmacokinetics, biodistribution, clinical efficacy and tolerability of genetically engineered protein therapeutics. Differences in glycosylation, which may affect immunogenicity and mannose-6-phosphate receptor-mediated cellular internalisation of administered enzyme, possibly account for the differences in dosing, clinical effects and safety profiles reported for agalsidase alfa and agalsidase beta.

[Carbonic anhydrase inhibitors and calcium phosphate stones]

We report a case of a 33 years old female with a history of paroxystic hemidystonia treated by acetazolamide, a carbonic anhydrase inhibitor (CAI), and who developed two years after the initiation of this treatment bilateral radio-opaque stones. Laboratory tests revealed a hyperchloremic acidosis, an elevated urinary pH, a hypercalciuria, a severe hypocitraturia and numerous granulations of amorphous carbonated calcium phosphates and brushite crystals on urinary microscopic examination, the whole suggests a diagnosis of acetazolamide-induced nephrolithiasis. We discuss in this article the lithogenetic process and the usual composition of the stones induced by CAI, and specific risk factors for developing drug-induced lithiasis which should be taken into consideration when prescribing long-term drug regimens.

A young man with a renal colic

We report the case of a 35-year-old man with no cardiovascular morbidity, presenting with acute flank pain, microscopic haematuria and normal blood pressure. Initially diagnosed as a ureteral colic, the patient was recovered 6 weeks later with severe hypertensive crisis. Further investigations revealed a massive renal infarction secondary to medial fibromuscular dysplasia (FMD). Several aspects of this presentation are intriguing. Renal infarcts are usually seen in older patients having cardiac problems and/or major atheromatous plaques. In addition, FMD is mainly observed in young females and rarely progresses to renal artery occlusion. Furthermore, in this case, FMD remained silent until the acute renal infarction occurred, despite a significant kidney size reduction at the time of diagnosis. Finally, the observation of a delayed hypertensive response to a major renovascular insult provides incentives to discuss possible pathophysiological mechanisms involved in renovascular hypertension.

Dual transplant of marginal kidneys. Case report and review of the literature

INTRODUCTION

Double transplantation is one possible answer to the shortage of donor organs. While each donor kidney would be unsuitable when considered as a single allograft, use of both kidneys should provide sufficient nephron mass for effective glomerular filtration.

CASE REPORT

This is the first Swiss report of a dual adult transplant of marginal kidneys in a 46-year-old man, who was transplanted for the fourth time. Follow-up at 6 months is excellent without acute rejection.

CONCLUSION

Recent analysis of dual marginal versus single ideal transplant outcomes, found a comparable 1-yr graft survival in both of the procedures. Long term results are still lacking and guidelines to decide between single, double or no transplantation are emerging.

[Orthostatic proteinuria and compression of the left renal vein (nutcracker syndrome)]

INTRODUCTION

The pathogenic mechanism of orthostatic proteinuria has not yet been clearly established.

OBSERVATION

In a tall, thin, 21 year-old man, isolated proteinuria was discovered during an urological control conducted one year after a bilateral orchidopexy following left testicular torsion. Proteinuria was orthostatic. Doppler examination of the kidney revealed an entrapment of the left renal vein (nutcracker phenomenon-NCP).

COMMENTS

An NCP was diagnosed in a young patient presenting with orthostatic proteinuria. By provoking modifications in intraglomerular haemodynamics, the NCP may, in nearly half of the cases, be at the origin of orthostatic proteinuria. Doppler examination is the diagnostic method of choice in the screening for NCP.

[Fabry disease in adulthood: clinical aspects and therapeutic progress]

INTRODUCTION

Fabry disease is an X-linked recessive abnormality of glycosphingolipid metabolism that is due to deficiency of the lysosomal enzyme alpha-galactosidase A.

CURRENT KNOWLEDGE AND KEY POINTS

A majority of hemizygous men develop severe multisystemic disease (classic form), dominated by renal failure, progressive neurological and cardiac involvement. Nevertheless, some affected men retain sufficient enzyme activity and long remain asymptomatic (atypical form); their main manifestation is hypertrophic cardiomyopathy. Female heterozygous carriers are usually asymptomatic; 15% of them, however, have severe involvement of one or several organs. Laboratory, histologic and molecular diagnosis identifies 100% of hemizygous and over 80% of heterozygous subjects.

FUTURE PROSPECTS AND PROJECTS

With developments in molecular genetics, it is now possible to produce the human recombinant enzyme alpha-galactosidase A. Two recent studies had proven that this therapeutic approach was able to be clinically and histologically effective in men. In addition, the results of a trial of gene therapy in a Fabry gene knocked-out mouse appear promising.

Renal disease in Fabry patients

Renal dysfunction is a major complication in hemizygous males with Fabry disease. This often results in end-stage renal failure (ESRF), requiring dialysis or transplantation, on average 10 years after the start of renal impairment. ESRF usually occurs between 40 and 50 years of age, but may occur much earlier. Although progression of renal disease can be rapid, it is variable and may depend on whether there is residual alpha-galactosidase enzyme activity and on environmental or genetic factors. Significant renal disease is much less common in women carriers of the disease. However, renal changes do occur, which may progress to ESRF as in male patients.

[Fabry disease: clinical aspects and therapeutic perspectives]

Fabry's disease is one of the lysosomal disorders. It is due to a hereditary alpha-galactosidase A defect with X-linked recessive transmission. A majority of hemizygotes develop severe multisystemic involvement (classic form), dominated by relentless renal failure and progressive neurological and cardiac lesions. Nevertheless, some affected individuals retain sufficient enzyme activity and long remain asymptomatic (atypical form); their main manifestation is hypertrophic cardiomyopathy. Female carriers are usually asymptomatic; 15%, however, have severe involvement of one or more organs. Laboratory, histological and molecular diagnosis identifies 100% of hemizygotes and over 80% of heterozygotes. With recent developments in molecular genetics it is possible to produce the human recombinant enzyme alpha-GALA. Its effects in hemizygous patients remain to be evaluated. In addition, the results of a trial of gene therapy in a Fabry's disease gene knocked-out mouse appear promising. These new therapeutic approaches will probably soon provide substitutive treatment for Fabry's disease as well as for so-called "orphan" diseases.

Medical treatment of cystinuria: critical reappraisal of long-term results

PURPOSE

We evaluated long-term results of a contemporary medical therapeutic regimen in patients with cystinuria and analyzed factors predictive of therapeutic success.

MATERIALS AND METHODS

A total of 27 adults with cystine urolithiasis were treated at our institution for 1.3 to 32 years (mean 11.6, overall 312 patient-years). We obtained data on the pre-referral period for 274 patient-years overall. Basic therapy included hyperdiuresis and alkalization. The thiols D-penicillamine or tiopronin were added when standard therapy failed to prevent new stones and stone growth or dissolve preexisting stones. X-ray and echography were performed every 4 months during the initial 2 years and every 6 months thereafter.

RESULTS

In the pre-referral period 256 stone episodes occurred and 81 urological procedures were performed in 24 patients (0.93 and 0. 29 per patient-year, respectively). Nine patients were treated with added thiols. During the therapeutic period the incidence of stone episodes decreased to 66 (0.20 per patient-year, p <0.001), while the need for urological procedures decreased to 44 (0.14 per patient-year, p <0.001). No further urological procedures were required in 15 patients, including 4 treated with thiols. However, the remaining 12 patients, including 5 treated with thiols, underwent 1 to 7 procedures each (mean 0.26 per patient-year). In the 2 groups mean daily cystine excretion plus or minus standard deviation at baseline (863 +/- 253 versus 761 +/- 270 mg. daily) and mean urinary pH of about 7.4 did not differ significantly. However, daily urine volume was significantly higher in patients with arrested stone formation (3,151 +/- 587 versus 2,446 +/- 654 ml./24 hours, p = 0.006).

CONCLUSIONS

Our study provides evidence that a regularly followed medical program based on high diuresis and alkalization with second line addition of thiols may arrest or markedly decrease cystine stone formation and preclude the need for urological procedures in more than half of the patients. However, patients poorly compliant with hyperdiuresis remain at risk for recurrence. We suggest that maintaining a daily urine volume of greater than 3 l. is essential for therapeutic success regardless of whether thiol derivatives are administered.

[Medical treatment of cystinuria: evaluation of long-term results in 30 patients]

OBJECTIVE

Because urinary hyper-excretion of cystine is permanent in homozygous cystinuric patients, stone recurrence is frequent and may alter renal function. Identification of factors predictive of success of medical treatment (no further urological procedure required) is therefore needed to improve patient management.

PATIENTS AND METHODS

Thirty adult patients with homozygous cystinuria and urolithiasis were referred to the nephrology department of the Necker Hospital from 1963 to 1999, with a mean follow-up of medical therapy of 10.5 +/- 8.4 years. The basal treatment schedule was hyperdiuresis and alkalinization with thiol derivative (D-penicillamine or tiopronine) added when needed.

RESULTS

Overall incidence of urological procedures decreased from 0.33/pt-year in the pretherapeutic period to 0.15 on treatment (p < 0.01), a 55% reduction. Sixteen patients (53%) did not require any urological procedure during follow-up. The only significant difference between those patients and the other 14 in whom medical therapy failed was the daily urine volume (3.2 l/day in the former compared with 2.4 l/day in the latter, p < 0.001).

CONCLUSION

Regular medical therapy was able to stop stone disease activity in the long term in more than half of the patients. Sustained hyperdiuresis, with a daily urine volume > 3 liters, appears as a major factor of therapeutic success, even in patients treated with thiols.

[Quantitative measure of the output of the deep abdominal vessels with a new device Duplex. Preliminary results]

Deep abdominal vessels blood flow can be measured noninvasively with the relation Q = V x A, where Q = flow, V = blood velocity and A = area of the considered vessel. In most Duplex devices, V is only calculated as a mean by the Doppler effect and A estimated by an echograph. Our newly developed multi-gated pulsed Doppler provides the velocity profile across the vessel, so minimizing errors in flow determination. On fifty healthy volunteers, we found flow of 717 +/- 238 ml/min for the portal vein, 1594 +/- 293 ml/min for the upper abdominal aorta and 794 +/- 168 ml/min for the lower aorta. These results are obtained through many technical and practical problems, but are feasible, even if still subject to errors. Further investigation will determine if the technique is also suitable for patients. Better assessment of deep abdominal vessels hemodynamics may be expected.