Chronic dialysis-associated anaemia in end-stage renal disease: analysis of management in two French centres.

BACKGROUND: Treatment of anaemia in renal-insufficient patients relies on the use of an erythropoiesis-stimulating agent (ESA). This study aimed to compare the impact of two different strategies of ESA prescribing on variation in haemoglobin (Hb) concentration in end-stage renal disease (ESRD) patients. METHODS: Patients with ESRD, on haemodialysis, and who had received ESA for >3 months were recruited. Different parameters were analysed: demographics, Hb level the last day of the year before dialysis, the most recent weekly ESA dose, risk factors for resistance and cost. Each institution continued its local practice for achieving the desired Hb level: increasing the ESA dose to overcome resistance in one centre and defining an upper ESA-dose limit in the other. RESULTS: A total of 185 patients were recruited. No significant differences in the biological parameters were found between the two populations. In both centres, Hb levels were comparable and mean levels exceeded 11 g/dL, despite the higher ESA doses given in one centre to achieve this target. This finding also held true for the subgroups with greater than or equal to two resistance factors. These two strategies led to large between-centre differences in treatment costs. CONCLUSION: The ESA-use strategy difference probably indicates that erythropoietin-resistance was not overcome with increased dosing. The Hb concentrations remained stable even when ESA doses were increased. On current evidence, the cheaper ESA-dose limitation strategy is preferable but randomized controlled studies, including comparisons of alternative ESA formulations are necessary.

Drug-protein interaction with Vpu from HIV-1: proposing binding sites for amiloride and one of its derivatives.

Vpu is an 81-amino-acid auxiliary protein of the genome of HIV-1. It is proposed that one of its roles is to enhance particle release by self-assembling to form water-filled channels enabling the flux of ions at the site of the plasma membrane of the infected cell. Hexamethylene amiloride has been shown to block Vpu channel activity when the protein is reconstituted into lipid bilayers. In a docking approach with monomeric, pentameric and hexameric bundle models of Vpu corresponding to the transmembrane part of the protein, a putative binding site of hexamethylene amiloride is proposed and is compared with the site for the nonpotent amiloride. The binding mode for both ligands is achieved by optimizing hydrogen bond interactions with serines. Binding energies and binding constants are the lowest for protonated hexamethylene amiloride in the pentameric bundle.

Full length Vpu from HIV-1: combining molecular dynamics simulations with NMR spectroscopy.

Based on structures made available by solution NMR, molecular models of the protein Vpu from HIV-1 were built and refined by 6 ns MD simulations in a fully hydrated lipid bilayer. Vpu is an 81 amino acid type I integral membrane protein encoded by the human immunodeficiency virus type-1 (HIV-1) and closely related simian immunodeficiency viruses (SIVs). Its role is to amplify viral release. Upon phosphorylation, the cytoplasmic domain adopts a more compact shape with helices 2 and 3 becoming almost parallel to each other. A loss of helicity for several residues belonging to the helices adjacent to both ends of the loop region containing serines 53 and 57 is observed. A fourth helix, present in one of the NMR-based structures of the cytoplasmic domain and located near the C-terminus, is lost upon phosphorylation.

[Results of systematic subtotal parathyroidectomy with thymectomy for tertiary hyperparathyroidism after renal transplantation - 70 patients]. / Résultats de la parathyroïdectomie subtotale de principe associée à une thymectomie systématique pour le traitement de l'hyperparathyroïdisme tertiaire après transplantation rénale chez 70 patients.

BACKGROUND: Due to the relatively small number of patients involved, there is currently no consensus on what operation should be performed in patients with tertiary hyperparathyroidism after renal transplantation. METHOD: Retrospective analysis of the 70 patients with tertiary hyperparathyroidism who all underwent subtotal parathyroidectomy with transcervical thymectomy in the same institution between 1978 and 2003. RESULTS: The delay between transplantation and parathyroidectomy was 4,1+/-4,3 years. Follow up was available for all patients. Mean follow-up was 5,6+/-5 years. Glomerular filtration rate (GFR) was 53+/-21 ml/min at parathyroidectomy and 42+/-29 ml/min at follow-up [<30 ml/min in 26 patients (37%), 30 - 60 ml/min in 25 patients (36%) et>60 ml/min in 19 patients (27%)]. One patient was successfully reoperated for persistent tertiary hyperparathyroidism during follow-up. No patient was hypercalcemic at follow-up. Four patients with a GFR<30 ml/min had a PTH level>fourfold normal values (6%) without signs or symptoms of hyperparathyroidism. One patient was hypocalcemic (1,5%) and two patients were normocalcemic with undetectable or infranormal PTH level (3%) under oral vitamin D and calcium medication. CONCLUSION: This approach permits not only to cure the majority of patients with tertiary hyperparathyroidism but also to avoid recurrence when the renal function declines. When medical management has failed, we recommend systematic subtotal parathyroidectomy with thymectomy for patients with tertiary hyperparathyroidism and this should usually be performed during the second year after transplantation.

Thrombotic microangiopathy in adult Still's disease.

Adult Still's disease (ASD) is a rare systemic disorder characterized by fever, arthralgia, cutaneous rash, and lymphadenopathy, with high polymorphonuclear leucocytosis and low glycosylated ferritinaemia. Kidney involvement has been reported rarely. We present a patient with ASD who developed haemolytic uraemic syndrome (HUS). The 42-year-old patient was admitted for unexplained fever related to ASD according to Yamaguchi's classification criteria. As Still's disease was resistant to prednisone, high-dose intravenous immunoglobulins (IV Ig) were administered. During the follow-up the patient developed acute renal failure and non-immune haemolytic anaemia with high levels of antiphospholipid antibodies (IgG anticardiolipin antibodies and anti-beta2 glycoprotein 1 antibodies). Renal biopsy disclosed thrombotic microangiopathy (TMA) with arteriolar and glomerular involvement. Treatment with steroids and intravenous IV Ig was reinitiated but renal function worsened towards end-stage renal failure. In this case, we suggest that antiphospholipid antibodies could have promoted arteriolar and glomerular TMA. HUS may be the cause of acute renal failure in Still's disease.

[Familial small-vessel vasculitis of the kidney]. / Vascularite familiale des vaisseaux de petit calibre des reins.

INTRODUCTION: Familial forms of small-vessel vasculitis has been reported in 14 families (including this one). CASES: A father and son were both diagnosed with renal vasculitis (pauci-immune crescentic glomerulonephritis). Both had antimyeloperoxidase autoantibodies, and there was no evidence of a common environmental factor. DISCUSSION: These cases suggest the role of constitutional factors in the pathogenesis of antineutrophil cytoplasmic antibody-associated vasculitis.

A review of oxygen-17 solid-state NMR of organic materials--towards biological applications.

17O solid state NMR of organic materials is developing rapidly. This article provides a snapshot of the current state of development of this field. The NMR techniques and enrichment protocols that are driving this progress are outlined. The (17)O parameters derived from solid-state NMR experiments are summarized and the structural sensitivity of the approach to effects such as hydrogen bonding highlighted. The prospects and challenges for (17)O solid-state NMR of biomolecules are discussed.

Proximal tubular dysfunction in primary Sjögren's syndrome: a clinicopathological study of 2 cases.

Tubulointerstitial nephritis is the most common renal complication in primary Sjögren's syndrome (SS). It is usually associated with symptoms of distal tubular dysfunction, type I (distal) renal tubular acidosis (RTA) and nephrogenic diabetes insipidus. Proximal tubular abnormalities are considered to be less frequent, and Fanconi's syndrome has been only exceptionally reported in patients with SS. We describe 2 patients with primary SS, characterized by xerostomia, dry eyes, extensive lymphocytic infiltrate on salivary gland biopsy, positive tests for anti-SSA/SSB antibodies and/or antinuclear antibodies, who presented in renal failure with proteinuria, microscopic hematuria and type I RTA. Further studies revealed proximal tubular dysfunction, including renal glucosuria, generalized aminoaciduria, phosphaturia, uricosuria, together with proximal (type II) RTA in 1 case. Neither of these patients had Bence Jones proteinuria or monoclonal gammopathy. Kidney biopsy showed focal proximal tubulitis, associated with proximal tubular cell atrophy and dedifferentiation, and diffuse interstitial nephritis with fibrosis. No significant glomerular or peritubular deposits of immunoglobulin light or heavy chain were observed. These findings demonstrate that diffuse, distal and proximal, tubular dysfunction may occur in patients with SS and interstitial nephritis. Lymphocytic infiltration of proximal tubular cells is probably involved in the pathogenesis of Fanconi's syndrome in SS. However, the mechanisms involved in the alteration of sodium-dependent apical transports remain to be elucidated.

Epoetin in haemodialysis patients: impact of change from subcutaneous to intravenous routes of administration.

BACKGROUND AND OBJECTIVE: Cases of erythroblastopenia, as an adverse effect to epoetin (EPREX), led to its use being restricted in Europe to the intravenous route (i.v.) since July 2002, in patients with chronic renal insufficiency. This work aimed at investigating the biological, pharmaceutical and economic impacts of this change in policy. METHODS: We retrospectively compared the characteristics of 99 haemodialysis patients treated with epoetin at the time of the recommendation (July 2002) and 5 months after the policy change (November 2002). RESULTS: In July 2002, 69 patients who were receiving EPREX subcutaneously (s.c./i.v. group) changed to the i.v. route of administration. Thirty other patients were already on i.v. epoetin (i.v. group). During the study period, the dose of epoetin increased significantly in the s.c./i.v. group but not in the i.v. group (46.83 +/- 10.20 UI/kg/week vs. 2.17 +/- 20.14 UI/kg/week respectively). This increased dosage was accounted for by a subgroup of 42 patients in the s.c./i.v. group while the others had dosage variations similar to those observed in the i.v. group. There were no significant clinical and biological changes associated with this change in route of administration. However, the change in policy led to the haemodialysis ward incurring an additional cost of 265,905 Euro (+32.7%) or an average annual extra cost of 1841 +/- 401 Euro per patient. CONCLUSION: Changing the route of administration of EPREX from the i.v. to the subcutaneous route required an increase in dosage and in substantial additional cost.

Interaction of amiloride and one of its derivatives with Vpu from HIV-1: a molecular dynamics simulation.

Vpu is an 81-residue membrane protein, with a single transmembrane segment that is encoded by HIV-1 and is involved in the enhancement of virion release via formation of an ion channel. Cyclohexamethylene amiloride (Hma) has been shown to inhibit ion channel activity. In the present 12-ns simulation study a putative binding site of Hma blockers in a pentameric model bundle built of parallel aligned helices of the first 32 residues of Vpu was found near Ser-23. Hma orientates along the channel axis with its alkyl ring pointing inside the pore, which leads to a blockage of the pore.

Molecular dynamics simulations on the first two helices of Vpu from HIV-1.

Vpu is an 81 amino acid protein of HIV-1 with two phosphorylation sites. It consists of a short N-terminal end traversing the bilayer and a longer cytoplasmic part. The dual functional role of Vpu is attributed to these topological distinct regions of the protein. The first 52 amino acids of Vpu (HV1H2) have been simulated, which are thought to be embedded in a fully hydrated lipid bilayer and to consist of a transmembrane helix (helix-1) connected via a flexible linker region, including a Glu-Tyr-Arg (EYR) motif, with a second helix (helix-2) residing with its helix long axis on the bilayer surface. Repeated molecular dynamics simulations show that Glu-28 is involved in salt bridge formation with Lys-31 and Arg-34 establishing a kink between the two helices. Helix-2 remains in a helical conformation indicating its stability and function as a "peptide float," separating helix-1 from the rest of the protein. This leads to the conclusion that Vpu consists of three functional modules: helix-1, helix-2, and the remaining residues toward the C-terminal end.

[Camptocormia: a sign of axial myopathy. Report of 7 cases]. / La camptocormie: un signe de myopathie axiale. A propos de sept observations.

PURPOSE: Camptocormia or progressive lumbar kyphosis is an anterior bend of the trunk. It appears in orthostatism or while walking and is reducible in the decubitus position. It concerns patients older than 60 years of age. It is due to a fatty degeneration of the paravertebral muscles, although the physiopathology remains unclear. METHODS: We report seven cases of camptocormia revealing authentic myopathies. RESULTS: Our observations concern five women and two men of 55 to 72 years of age. All patients present lumbar kyphosis and had a fatty involution of the paraspinal muscles on the muscular MRI. Four patients fulfilled the Bohan and Peter criteria of polymyositis and dermatomyositis. In the other cases paravertebral muscular biopsies led to the diagnosis of a congenital myopathy, a mitochondrial myopathy and an amyloid myopathy. Four patients received a corticosteroid-immunoglobulins or cyclosporin regimen. An improvement in the camptocormia was observed in three cases. In the other cases the treatment consisted of chemotherapy on account of severe nephrotic syndrome, a coenzyme-Q treatment for the patient with mitochondrial myopathy and only physiotherapy in the case of congenital myopathy, but without positive effect on camptocormia. CONCLUSION: Camptocormia appears as a muscular symptom that may reveal an axial myopathy due to multiple and varied pathologies. Thus, the discovery of camptocormia requires an aetiological investigation in order to propose an adequate treatment, which should be associated with physiotherapy.

ApoE knockout mice expressing human matrix metalloproteinase-1 in macrophages have less advanced atherosclerosis.

Matrix metalloproteinase-1 (MMP-1), or interstitial collagenase, has been hypothesized to contribute to the progression of the human atherosclerotic lesions by digesting the fibrillar collagens of the neointimal ECM. The apolipoprotein E knockout (apoE0) mouse model develops complex atherosclerotic lesions, but mice do not possess a homologue for MMP-1. To provide an in vivo evaluation of the role of MMP-1 in atherogenesis, we created a transgenic mouse model that expresses this enzyme specifically in the macrophage, under the control of the scavenger receptor A (SCAV) enhancer/promoter. The MMP-1 transgenic mice were crossed into the apoE0 background and fed an atherogenic diet for 16-25 weeks. Surprisingly, the transgenic mice demonstrated decreased lesion size compared with control littermates. The lesions of the transgenic animals were less extensive and immature, with fewer cellular layers and a diminished content of fibrillar collagen. There was no evidence of plaque rupture. Our data suggest that remodeling of the neointimal extracellular matrix by MMP-1 is beneficial in the progression of lesions.

Structure of recombinant mouse collagenase-3 (MMP-13).

The matrix metalloproteinases are crucial in the physiological and pathological degradation of the mammalian extracellular matrix, including breast tumours, and osteoarthritic cartilage. These enzymes are classified according to their matrix substrate specificity. Collagenase-3 (MMP-13) is a member of this family and preferentially cleaves type II collagen, cartilage, fibronectin and aggrecan. Collagenase-3 is normally expressed in hypertrophic chondrocytes, periosteal cells, and osteoblasts during bone development. The structure of the catalytic domain of recombinant mouse collagenase-3, complexed to the hydroxamate inhibitor (RS-113456), is reported at 2.0 A resolution. Molecular replacement and weak phasing information from a single derivative determined the structure. Neither molecular replacement nor derivative methods had a sufficient radius of convergence to yield a refinable structure. The structure illuminates the atomic zinc ion interactions with functional groups in the active site, emphasizing zinc ligation and the very voluminous hydrophobic P1' group for the inhibitor potency. The structure provides insight into the specificity of this enzyme, facilitating design of specific inhibitors to target various diseases.

Renal thrombotic microangiopathy in systemic lupus erythematosus: clinical correlations and long-term renal survival.

BACKGROUND: Renal thrombotic microangiopathy (TMA) is an uncommon vascular complication of systemic lupus erythematosus (SLE). Its clinical symptoms and impact on renal survival remain unclear. METHODS: Eight patients aged 25 +/- 6 years with biopsy-proven renal TMA and at least four ARA criteria for the diagnosis of SLE were retrospectively studied over a 7-year period. RESULTS: All patients presented with renal failure (creatinine 3.3 +/- 2.1 mg/dl), six had proteinuria (2.5 +/- 1.3 g/day) with microscopic haematuria in four cases. Six patients had hypertension, which was severe in five cases. Renal histology disclosed arterial and/or arteriolar thrombosis with parietal thickening without angeitis (8 patients), glomerular microthrombi (3 patients), and vascular fibrin deposits (5/6 patients). In two cases, vascular lesions were associated with a mesangial or a proliferative glomerulonephritis. Thrombocytopenia was present in four patients with haemolytic microangiopathic anaemia in one case. Lupus anticoagulant (LA) was detected in five of eight patients, who also had anticardiolipin antibodies (3/7 patients) and/or were positive for VDRL (3/6 patients). Four patients with LA experienced arterial thrombosis and/or repeated spontaneous abortions. Treatment consisted of corticosteroids (8 patients), cytotoxic drugs (4 patients), plasma exchanges and/or intravenous immunoglobulins (4 patients) and antiplatelet and/or anticoagulant therapy (3 patients). Two patients recovered normal renal function and five had persistent renal insufficiency. One patient started haemodialysis on admission and died of sepsis 2 months later. CONCLUSIONS: TMA may be the sole renal complication in SLE and is not usually associated with haemolytic microangiopathic anaemia. In our series renal survival was influenced by the extent and severity of vascular lesions. Despite a frequent association with antiphospholipid antibodies, pathophysiological mechanisms of renal TMA in SLE remain unknown. Renal histology is mandatory for the diagnosis and the prognostic evaluation of renal vasculopathy in SLE.

Urokinase-generated plasmin activates matrix metalloproteinases during aneurysm formation.

The molecular mechanisms predisposing to atherosclerotic aneurysm formation remain undefined. Nevertheless, rupture of aortic aneurysms is a major cause of death in Western societies, with few available treatments and poor long-term prognosis. Indirect evidence suggests that matrix metalloproteinases (MMPs) and plasminogen activators (PAs) are involved in its pathogenesis. MMPs are secreted as inactive zymogens (pro-MMPs), requiring activation in the extracellular compartment. Plasmin, generated from the zymogen plasminogen by tissue-type plasminogen activator (t-PA) or urokinase-type plasminogen activator (u-PA; refs 14,15), has been proposed as a possible activator in vitro, but evidence for such a role in vivo is lacking. Analysis of atherosclerotic aorta in mice with a deficiency of apoliprotein E (Apoe-/-; ref. 18), singly or combined with a deficiency of t-PA (Apoe-/-:Plat-/-) or of u-PA (Apoe-/-:Plau-/-; ref. 19), indicated that deficiency of u-PA protected against media destruction and aneurysm formation, probably by means of reduced plasmin-dependent activation of pro-MMPs. This genetic evidence suggests that plasmin is a pathophysiologically significant activator of pro-MMPs in vivo and may have implications for the design of therapeutic strategies to prevent aortic-wall destruction by controlling Plau gene function.

The recombinant catalytic domain of mouse collagenase-3 depolymerizes type I collagen by cleaving its aminotelopeptides.

The sequence coding for the catalytic domain of mouse collagenase-3 (MMP-13) was amplified by polymerase chain reaction and expressed in Escherichia coli. The recombinant catalytic domain (CCD), mainly recovered as inclusion bodies, was renatured and purified to homogeneity by preparative SDS-PAGE. The purified CCD degraded gelatin, casein and a synthetic peptide. CCD was not able to cleave the triple-helical domain of type I collagen but conserved the specific property of full-length collagenase-3 to cleave the N-telopeptides. These results show that residues involved in the recognition and cleavage of the aminotelopeptides of type I collagen are located in the catalytic domain of mouse collagenase-3 and that the C-terminal domain is not required for this activity.

Different collagenase gene products have different roles in degradation of type I collagen.

Vertebrate collagenases, matrix metalloproteinases (MMPs), cleave type I collagen at a single helical locus. We show here that rodent interstitial collagenases (MMP-13), but not human fibroblast collagenase (MMP-1), cleave type I collagen at an additional aminotelopeptide locus. Collagenase cDNAs and chimeric constructs in pET-3d, juxtaposing MMP-13 sequences amino-terminal to the active site in the catalytic domain and MMP-1 sequences carboxyl-terminal and vice versa, were expressed in Escherichia coli. Assays utilized collagen from wild type (+/+) mice or mice that carry a targeted mutation (r/r) that encodes substitutions in alpha1(I) chains that prevent collagenase cleavage at the helical locus. MMP-13 and chimeric molecules that contained the MMP-13 sequences amino-terminal to the active site cleaved (+/+) collagen at the helical locus and cleaved cross-linked (r/r) collagen in the aminotelopeptide (beta components converted to alpha chains). Human MMP-1 and chimeric MMP-1/MMP-13 with MMP-1 sequences amino-terminal to the active site cleaved collagen at the helical locus but not in the aminotelopeptide. All activities were inhibited by TIMP-1, 1,10-phenanthroline, and EDTA. Sequences in the distal two-thirds of the catalytic domain determine the aminotelopeptide-degrading capacity of MMP-13.