Right ventricle function improvement after six month of therapy with Sacubitril/Valsartan in a real-life population of patients with chronic heart failure with reduced ejection fraction

Funding Acknowledgements

Type of funding sources: None.

Background

 Observational studies have demonstrated that treatment with sacubitril/valsartan may improve left ventricular (LV) systolic and diastolic function in subjects with reduced LV ejection fraction (LVEF) in real-world studies. Subjects with heart failure and reduced EF (HFrEF), however, are also characterized by an impaired right ventricular (RV) function. We therefore aimed to evaluate whether also RV function may improve after S/V therapy and possible predictors of RV improvement could be identified at echocardiography and tissue Doppler imaging. 

Methods

 Fifty consecutive patients (67 ± 8 years, LVEF 28 ± 6%, male 86%) with chronic HFrEF and NYHA class II-III were followed up for 6 months after therapy with S/V. L&RV function was assessed at baseline and after 6 months of therapy. 

Results

 After 6-month therapy with S/V a significant improvement was shown in the following echocardiography  parameters  assessing RV function: PAsP(31 ± 11vs 35 ± 10mmHg,p < 0.001),

TAPSE(19 ± 3vs18 ± 3mm,p < 0.001),RVFAC(38 ± 7 vs 34 ± 6 mm,p < 0.001), RVS’(12 ± 2vs10 ± 2cm/sec,p < 0.001), RVFWGLS(-20 ± 5vs-18 ± 5%,p < 0.001), RV4ChGLS (-16 ± 5vs-14 ± 5%,p < 0.001). At multivariable analysis improvement in RVFWGLS was associated to baseline levels of RV S’ (r 0.75, p < 0.01) and RAV (r–0.32,p < 0.05). 

Conclusions

 In a real-world scenario, 6-month therapy with S/V was associated with an improved RV function in HFrEF. RV function improvement may be predicted by assessing baseline RV S’ and right atrial volume values.

Left atrial functional reverse remodeling assessed by speckle tracking echocardiography in a real-life population of patients with chronic heart failure after therapy with sacubitril/valsartan

Funding Acknowledgements

Type of funding sources: None.

Background

Left atrial (LA) enlargement has been demonstrated to be a predictor of adverse cardiovascular outcomes, such as atrial fibrillation (AF), heart failure (HF), and cardiovascular death (1). Previous studies showed left atrial structural reverse remodeling (LARR), defined as >15% reduction in LA end-systolic volume index (LAESVi) (2), can be achieved after therapy with Sacubitril/Valsartan (S/V) in real-world settings. On the other hand, LA functional reverse remodeling is not well defined.

Purpose

We sought to investigate the association between left atrial (LA) structural and functional remodelling in patients with chronic heart failure after therapy with S/V.

Methods

Patients with chronic HF, LV dysfunction (EF < 35%), NYHA class II-III were followed up between September 2019 and March 2020. All patients underwent clinical and echocardiography follow up at baseline and after 6 months of therapy with S/V. Measures of LA structure [LA end-systolic volume index (LAESVi)] and function [left atrial ejection fraction (LAEF), peak atrial longitudinal strain (PALS), LA conduit strain, and peak atrial contraction strain (PACS)] were calculated. We divided our population into two subgroups based on whether reverse remodeling was achieved (LARR+) or not (LARR-).

Results

Forty-seven consecutive outpatients (mean age 66 ± 8 years; 85% males) were enrolled in the study. At follow-up visit, a positive LARR was found in nearly half of patients treated with S/V, resulting in line with previous studies (3). Furthermore, global PALS was significantly improved in both groups compared to baseline (15 ± 7 vs 19 ± 8 %, p < 0.001), but the LARR+ group showed an improvement that was twice higher (55 ± 66 vs 25 ± 26, p = 0.039), supporting the potential role of PALS as marker of functional LARR.

Conclusions

Treatment with S/V in patients with systolic dysfunction is associated with an improvement in LA structural and functional remodelling in a real-world scenario. Therefore, PALS could be the benchmark for the assessment of left atrial functional reverse remodeling.

Optical coherence tomography angiography in Tuberous sclerosis complicated with macular choroidal neovascularization

This study describe the optical coherence tomography angiography (OCTA) features of a young patient with Tuberous sclerosis complicated with CNV unilateral macular choroidal neovascularization during the ranibizumab therapy. OCTA scans of macular region of right eye, revealed a dense microvascular network confirming the diagnosis of CNV. After four monthly intravitreal injections, OCTA revealed a decrease of size and activity of CNV. OCTA is a valid, non-invasive, dyeless, and reliable method that could improve the diagnosis and management of CNV in child with Tuberous sclerosis.

Is there long-term value of pathology scoring in immunoglobulin A nephropathy? A validation study of the Oxford Classification for IgA Nephropathy (VALIGA) update

Background

It is unknown whether renal pathology lesions in immunoglobulin A nephropathy (IgAN) correlate with renal outcomes over decades of follow-up.

Methods

In 1130 patients of the original Validation Study of the Oxford Classification for IgA Nephropathy (VALIGA) cohort, we studied the relationship between the MEST score (mesangial hypercellularity, M; endocapillary hypercellularity, E; segmental glomerulosclerosis, S; tubular atrophy/interstitial fibrosis, T), crescents (C) and other histological lesions with both a combined renal endpoint [50% estimated glomerular filtration rate (eGFR) loss or kidney failure] and the rate of eGFR decline over a follow-up period extending to 35 years [median 7 years (interquartile range 4.1–10.8)].

Results

In this extended analysis, M1, S1 and T1–T2 lesions as well as the whole MEST score were independently related with the combined endpoint (P < 0.01), and there was no effect modification by age for these associations, suggesting that they may be valid in children and in adults as well. Only T lesions were associated with the rate of eGFR loss in the whole cohort, whereas C showed this association only in patients not treated with immunosuppression. In separate prognostic analyses, the whole set of pathology lesions provided a gain in discrimination power over the clinical variables alone, which was similar at 5 years (+2.0%) and for the whole follow-up (+1.8%). A similar benefit was observed for risk reclassification analyses (+2.7% and +2.4%).

Conclusion

Long-term follow-up analyses of the VALIGA cohort showed that the independent relationship between kidney biopsy findings and the risk of progression towards kidney failure in IgAN remains unchanged across all age groups and decades after the renal biopsy.

Optical Coherence Tomography Angiography in Children with Leber-Coats Disease

INTRODUCTION

The aim of this work was to describe the optical coherence tomography (OCT) angiography (OCTA) features in paediatric Leber-Coats disease.

METHODS

Three children presenting with unilateral, clinically active Leber-Coats disease were evaluated using spectral domain OCT and OCTA. OCT angiograms were analysed and compared with the current literature.

RESULTS

All 3 OCT angiograms showed that the vessels had lost most of their collateral branches and presented many loops. The capillaries were rarefied and anomalies in vessel size, vasodilatation, and macroaneurysms were evident.

CONCLUSION

This is the first case series of OCTA performed in children with Leber-Coats disease. OCTA is a non-invasive and non-contact technique, which can be considered of fundamental importance for the diagnosis, clinical management, and follow-up of the disease.

The challenging management of pediatric corneal transplantation: an overview of surgical and clinical experiences

PURPOSE

Pediatric keratoplasty is an immense challenge because of the technical complexity of the procedure and the high risk of rejection in young graft recipients. Our aim is to describe the major indications and appropriate timing of corneal transplantation intervention, including a report of our experience and surgical tips, in conjunction with the current literature.

METHODS

Review of the literature on indications for keratoplasty in pediatric patients classified as: congenital, traumatic and acquired non-traumatic opacities. We additionally explored the challenges corneal surgeons face in performing this type of surgery and review the most pressing transplant-related problems and their management.

RESULTS

Outcomes after pediatric keratoplasty, in terms of visual development, restoration and clarity of the graft, are influenced by peri-operative local and systemic conditions and factors, and by intraoperative management of the transplantation procedure itself.

CONCLUSION

Pediatric corneal transplantation is a critical tool for visual restoration and development in young patients with corneal opacities, particularly during the critical period of visual development. Successful management of the significant challenges associated with pediatric keratoplasty requires customized clinical and surgical management of each patient with particular attention paid to proper post-operative rehabilitation.

Anterior ischemic optical neuropathy in children on chronic peritoneal dialysis: report of 7 cases

BACKGROUND

Anterior ischemic optic neuropathy (AION) is characterized by infarction of the optic nerve head due to hypoperfusion of the posterior ciliary arteries and causes sudden blindness in adults on chronic dialysis, but has rarely been described in children. Unlike adults, children do not have comorbidities related to aging.

METHODS

We retrospectively analyzed data of 7 children on nocturnal continuous cycling peritoneal dialysis (CCPD) who developed AION identified within the Italian Registry of Pediatric Chronic Dialysis. We also summarized data from 10 cases reported in the literature.

RESULTS

Our 7 patients suffered from acute onset bilateral blindness. Their mean age was 3.2 years and chronic hypotension had been observed prior the AION in 3 of the 7 children. Low systolic blood pressure (SBP) was associated with higher risk of developing AION according to statistical analysis. None recovered completely. In total, 11 out of 16 experienced a partial recovery and no clear evidence emerged favoring specific treatments.

CONCLUSIONS

Hypotensive children treated with CCPD are at increased risk of developing AION, which often results in irreversible blindness.

Photodynamic therapy in von Hippel-Lindau disease in children

Von Hippel-Lindau disease is characterized by retinal hemangiomas that often produce hemorrhages and retinal detachment. A 10-year-old boy with von Hippel-Lindau disease presenting with telangiectasias, endophytic angiomas, and exudative retinal detachment underwent treatment with retrobulbar steroid injection, laser photocoagulation, and photodynamic therapy, which led to improvement of visual acuity.

Thyrotropin-secreting pituitary adenomas: biological and molecular features, diagnosis and therapy

Central hyperthyroidism due to a thyrotropin (TSH)-secreting pituitary adenoma is a rare cause of hyperthyroidism, representing 0.5-1.0% of all pituitary adenomas. The etiopathogenesis of TSH-secreting-adenomas is unknown and no definite role for various oncogenes has been proven. Patients with TSH-secreting adenoma usually present with signs and symptoms of hyperthyroidism milder than those in patients with hyperthyroidism of thyroid origin, in addition to symptoms secondary to mass effects of the pituitary tumour. Mixed pituitary tumours co-secrete growth hormone and prolactin. The characteristic biochemical abnormalities are normal or high serum TSH concentrations in the presence of elevated total and/or free thyroid hormones concentrations. Measurement of markers of peripheral thyroid hormone action and dynamic tests may aid in the differential diagnosis with the syndrome of resistance to thyroid hormone. Neuroimaging is fundamental to visualize the pituitary tumor. Therapy of TSH-secreting adenomas can be accomplished by surgery, radiation therapies, and medical treatment with somatostatin analogs or dopamine agonists. Nowadays, and in contrast with the first reports on this rare disease, most patients are well controlled by current therapies.

[Recent advances in the prevention of cardiovascular morbidity and mortality in end-stage renal disease: role of anemia, hyperparathyroidism and calcifications]

The mortality rate in patients with end-stage renal disease (ESRD) is extremely high, mainly because of the high prevalence of cardiovascular disease. In addition to traditional cardiovascular risk factors, other factors peculiar to chronic kidney disease play a role. Anemia and calcium-phosphate disorders are of particular interest, not only because they have been related to an increased risk of death but, more importantly, because they can be reversed by treatment, thereby providing the opportunity to prevent or delay the onset of cardiovascular disease. Despite a clear association between higher hemoglobin levels and better survival, data from interventional trials do not seem to show a significant positive effect of hemoglobin normalization with erythropoiesis-stimulating agents on survival and left ventricular mass in ESRD patients. Nevertheless, partial correction of anemia is still an important goal to be reached, as is also suggested by international guidelines. Disorders of calcium-phosphate metabolism have also been clearly related to increased mortality. Unlike anemia, which can be easily corrected by treatment in most cases, mineral metabolism is much less effectively treated. New agents, such as phosphate binders not containing calcium and aluminum, vitamin D analogs with lower calcemic activity, and calcimimetics, are becoming increasingly available in everyday clinical practice and are likely to allow a higher percentage of patients to achieve the recommended targets for calcium-phosphate and parathyroid hormone. Given that these molecules have only been introduced recently, clear data from interventional studies showing improved survival after adequate correction of mineral metabolism parameters are still lacking.

Hypokalemic periodic paralysis in a patient with acquired growth hormone deficiency

CONTEXT

Hypokalemic periodic paralysis (HypoPP) is a rare disorder consisting of sudden episodes of muscle weakness with areflexia involving all four limbs, which spontaneously resolve within several hours or days. Primary HypoPP is genetically determined, while secondary acquired HypoPP has been described in association with thyreotoxycosis, hyperaldosteronism, kidney diseases, diuretics and liquorice abuse, gastrointestinal potassium loss, or cysplatinum therapy.

OBJECTIVE

To report a case of HypoPP associated with GH deficiency.

PATIENT

A 33 yr-old man with hypopituitarism and diabetes insipidus secondary to pituitary stalk-localized sarcoidosis, and documented HypoPP episodes.

CLINICAL PRESENTATION

Neurologic exam outside HypoPP episodes was normal. Needle electromyography was normal without myotonia or other spontaneous electric activity. Muscle biopsy documented a vacuolar myopathy with tubular aggregates. However, genetic analysis ruled out common mutations of the voltage-gated calcium channel observed in primary HypoPP. Common causes of secondary HypoPP were also ruled out. The patient was diagnosed with severe GH deficiency with modest fasting hyperinsulinemia and insulin resistance and started on GH replacement therapy, an alpha-glucosidase inhibitor (acarbose) and a diet low in simple carbohydrates.

CONCLUSIONS

GH replacement therapy, acarbose and a diet low in simple carbohydrates resulted in the complete long-term (>2 yr) remission of HypoPP episodes. This is consistent with the hypothesis that the hyperinsulinemia associated to GH deficiency may trigger HypoPP episodes by increasing Na+/K+ ATPase activity and K+ transport into the intracellular compartment with subsequent hypokalemia.

[Genetics and arterial hypertension: monogenic forms]

Hypertension is a complex, multifactorial disease; genetic factors represent one third to half of the inter-individual variability of blood pressure values. The study of genes involved in rare forms of monogenic hypertension led to the identification of pivotal pathophysiological pathways of kidney sodium and water reabsorption that can influence blood pressure values when changed. Glucocorticoid-Remediable Aldosteronism (GRA) is characterised by normal to high aldosterone levels, despite plasma renin activity suppression, and by the fact that these alterations are corrected by exogenous glucocorticoid administration. Apparent Mineralocorticoid Excess (AME) is due to a mutation of the gene encoding the renal isoform of 11 â HSD enzyme; the non-conversion of cortisol to cortisone result in increasing cortisol levels that activate the mineralocorticoid receptor. Early onset hypertension exacerbating during pregnancy is caused by a mutation leading to a conformational change in the mineralocorticoid receptor. Therefore, substances that are normally inactive at this level, such as progesterone, become potent agonists of the mutated receptor. Liddle's syndrome (or type I pseudo-hyperaldosteronism (PHA1), is characterised by a constitutive activation of the epithelial sodium channels in the distal tubule, causing an increase in sodium and chloride reabsorption. Gordon syndrome (Type II pseudo-hyperaldosteronism, PHA2) differs from the other forms because of the presence, in addition to hypertension, of hyperkaliemia and hyperchloremic acidosis that can be normalized with thiazide diuretics. Finally, a large pedigree of Turkish origin has been described: these patients are affected by an uncertain form of monogenic hypertension associated with brachydactyly.

Comparison between the analgesic and therapeutic effects of a musically modulated electromagnetic field (TAMMEF) and those of a 100 Hz electromagnetic field: blind experiment on patients suffering from cervical spondylosis or shoulder periarthritis

The analgesic-therapeutic efficacy and tolerability of a low-frequency electromagnetic field (ELF), modulated at a frequency of 100 Hz with a sinusoidal waveform and mean induction of a few gauss, has been demonstrated by the authors in numerous previous studies of various hyperalgic pathologies, particularly of the locomotor apparatus. In the present study, the authors tested a new type of all-inclusive field, denoted TAMMEF, whose parameters (frequency, intensity, waveform) are modified in time, randomly varying within the respective ranges, so that all the possible codes can occur during a single application. For the comparison, 150 subjects (118 women and 32 men, between 37 and 66 years of age) were enrolled. They were affected by cervical spondylosis (101 cases) or shoulder periarthritis (49 cases). Unbeknownst to them, they were randomly divided into three groups of 50 subjects. One group was exposed to the new TAMMEF, another group to the usual ELF, and the third group to simulated treatment. The results show that the effects of the new TAMMEF therapy are equivalent to those obtained with the ELF.

Molecular characterization and sequence analysis of polyomavirus strains isolated from needle biopsy specimens of kidney allograft recipients

We retrospectively examined 29 renal allograft biopsy specimens from 42 kidney transplant recipients by means of molecular biologic techniques (nested polymerase chain reaction), immunohistochemical analysis (anti-SV40 antibody), and histologic examination to evaluate the presence of polyomaviruses (PVs), viral genotypes, genomic mutations, and their pathologic significance. PV genomes were found in six cases (21%); restriction fragment length polymorphism analysis characterized 4 as JC virus (JCV) and 2 as BK virus (BKV). The latter also were positively stained immunohistochemically and showed histologically typical intranuclear viral inclusions; JCV cases were negative. DNA sequence analysis revealed only minor changes in the 4 JCV cases (3 archetypes and 1 JCV type 3, not associated with a known pathogenic genotype) but identified 2 specific variants in the BKV isolates (AS and WW strains). Given the different histologic findings (mixed inflammatory infiltration in the AS and no inflammation in the WW strain), we speculate that different BKV strains may cause differential damage in transplanted kidneys. Finally, the negative histologic and immunohistochemical JCV results, as well as the absence of viral mutations, indicate that JCV renal infection is latent in transplant recipients.

Molecular characterization and sequence analysis of polyomavirus strains isolated from needle biopsy specimens of kidney allograft recipients

We retrospectively examined 29 renal allograft biopsy specimens from 42 kidney transplant recipients by means of molecular biologic techniques (nested polymerase chain reaction), immunohistochemical analysis (anti-SV40 antibody), and histologic examination to evaluate the presence of polyomaviruses (PVs), viral genotypes, genomic mutations, and their pathologic significance. PV genomes were found in six cases (21%); restriction fragment length polymorphism analysis characterized 4 as JC virus (JCV) and 2 as BK virus (BKV). The latter also were positively stained immunohistochemically and showed histologically typical intranuclear viral inclusions; JCV cases were negative. DNA sequence analysis revealed only minor changes in the 4 JCV cases (3 archetypes and 1 JCV type 3, not associated with a known pathogenic genotype) but identified 2 specific variants in the BKV isolates (AS and WW strains). Given the different histologic findings (mixed inflammatory infiltration in the AS and no inflammation in the WW strain), we speculate that different BKV strains may cause differential damage in transplanted kidneys. Finally, the negative histologic and immunohistochemical JCV results, as well as the absence of viral mutations, indicate that JCV renal infection is latent in transplant recipients.

Molecular characterization and sequence analysis of polyomavirus BKV-strain in a renal-allograft recipient

The significance of polyomavirus (PV) infection was investigated in a 53-year-old patient who underwent renal transplantation and was treated with triple immunosuppressive therapy (tacrolimus, prednisone, and azathioprine). A renal biopsy taken because of the suspicion of acute rejection showed focal inflammatory interstitial infiltration, tubulitis, and tubular cell nuclear changes consistent with the hypothesis of viral infection. Both the tubular and decoy cells identified by means of urinalysis positively stained for anti-SV40 antibody. Polymerase chain reaction performed on the DNA extracted from renal tissue and isolated from urine showed the presence of an antigenic variant (AS) of the BKV archetype after sequence analysis of the transcription control region (TCR). On the basis of the diagnosis of BKV infection, immunosuppressive therapy was reduced. The patient's renal function improved and was still stable 8 months later when urinalysis showed only a few decoy cells, which were found to be infected by JC but not BK virus. These data suggest that only the BKV, probably favoured by immunosuppressive therapy (tacrolimus), causes renal damage. It is worth underlining that even small and sporadic viral genome mutations may lead to pathologic effects.

Activation of progelatinase A by mammalian legumain, a recently discovered cysteine proteinase

The activation of progelatinase A to gelatinase A requires cleavage of an asparaginyl bond to form the N-terminus of the mature enzyme. We have asked whether the activation can be mediated by legumain, the recently discovered lysosomal cysteine proteinase that is specific for hydrolysis of asparaginyl bonds. Addition of purified legumain to the concentrated conditioned medium from HT1080 cell culture that contained both progelatinases A and B caused the conversion of the 72 kDa progelatinase A to the 62 kDa form. The progelatinase B in the medium was unaffected. Incubation of recombinant progelatinase A with legumain resulted in an almost instantaneous activation as judged by the fluorometric assay with a specific gelatinase A substrate, Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2. Legumain also activated progelatinase A when it was in complex with TIMP-2. Zymographic analysis and N-terminal sequencing revealed that legumain cleaved the 72 kDa progelatinase A at the bonds between Asn109-Tyr110 or Asn111-Phe112 to produce the 62 kDa mature enzyme, and that further cleavage at Asn430 also occurred to generate a 36 kDa active form. More 62 kDa gelatinase A was detected in cultures of C13 cells that over-expressed legumain than in those of the control HEK293 cells. We conclude that legumain is clearly capable of processing progelatinase A to the active enzyme in vitro and in cultured cells.

[Evaluation of early biomarkers of cartilage degeneration in the diagnosis and clinico-therapeutic monitoring of primary osteoarthrosis]

It is known that in the course of osteoarthritis (OA), articular cartilage develops biochemical and structural changes. In the last years, serum and urinary markers of both the synthesis and destruction of cartilage have been dosed, above all in order to carry out an early diagnosis of OA. Among them, the urinary excretion of pyridinoline seems to correlate with the entity of the degradation of cartilage. The aim of the present study is to evaluate the above mentioned markers in OA patients compared to control subjects. Moreover, the possible influence on cartilage of two different non steroidal antiinflammatory drugs (NSAIDs), in particular Nabumetone and Piroxicam, has been verified. The study shows that the urinary excretion of pyridinoline is able to express the severity of OA. At last, the study shows that the tested drugs do not interfere with the metabolism of cartilage.

Toward a tomographic picture of a Bose-Einstein condensate

The possibilities of applying tomographic techniques to a Bose-Einstein condensate to reconstruct its ground state are investigated by means of numerical simulations. Two situations for which the density-matrix elements can be retrieved from atom counting probabilities are considered. The methods presented here allow one to distinguish among various possible quantum states.

Activation of human prolegumain by cleavage at a C-terminal asparagine residue

The processing and activation of prolegumain were studied using the recombinant protein synthesized by cells that had been stably transfected with a human legumain cDNA construct. A cell line termed C13 was selected for the high-level expression of prolegumain. C13 cells produced primarily 56 kDa prolegumain. The 56 kDa form was enzymically inactive but stable at neutral pH, unlike the 35 kDa mature pig legumain; it could be converted into a 46 kDa active form by incubation at pH 4.5. The 56 kDa pro-form and the 46 kDa active form were found to have the same N-terminal amino acid sequence, indicating that cleavage at the N-terminus was not necessary for prolegumain activation, and that the decrease in molecular mass was due to a C-terminal cleavage. The C-terminal processing site was identified as Asn(323). Replacement of Asn(323) at the cleavage site with aspartate, serine, alanine or glutamate abolished the processing and activation of prolegumain. In contrast, mutation of other asparagine and aspartate residues near the cleavage site had no effect. These results demonstrate that Asn(323) is essential for prolegumain activation.

Complete quantum teleportation with a kerr nonlinearity

We present a scheme for the quantum teleportation of the polarization state of a photon employing a cross-Kerr medium. The experimental feasibility of the scheme is discussed and we show that, using the recently demonstrated ultraslow light propagation in cold atomic media, our proposal can be realized with presently available technology.

Intraocular lens implantation in Marfan's syndrome

PURPOSE

To describe the results of the removal of ectopic lenses from patients with Marfan's syndrome using the scleral fixation method.

METHODS

Intraocular lenses (IOLs) were implanted in six eyes affected by lens dislocation (ectopia lentis) using either the scleral fixation method (five eyes) or a silicone IOL in the capsular bag (one eye). Mean patient age ranged from 8-11 years and follow-up ranged from 7-20 months.

RESULTS

Functional success was obtained in all eyes. Postoperative visual acuity was 20/20 to 20/40. One patient showed a dislocation of the IOL in the anterior chamber. In three eyes, an opacification of the posterior capsule was treated using an Nd:YAG laser.

CONCLUSION

Intraocular lens implantation using the scleral fixation technique is the first choice in patients with Marfan's syndrome because it reduces the complications of IOL decentration.

Pig kidney legumain: an asparaginyl endopeptidase with restricted specificity

Legumain was recently discovered as a lysosomal endopeptidase in mammals [Chen, Dando, Rawlings, Brown, Young, Stevens, Hewitt, Watts and Barrett (1997) J. Biol. Chem. 272, 8090-8098], having been known previously only from plants and invertebrates. It has been shown to play a key role in processing of the C fragment of tetanus toxin for presentation by the MHC class-II system [Manoury, Hewitt, Morrice, Dando, Barrett and Watts (1998) Nature (London) 396, 695-699]. We examine here the specificity of the enzyme from pig kidney by use of protein, oligopeptide and synthetic arylamide substrates, all determinations being made at pH 5.8. In proteins, only about one in ten of the asparaginyl bonds were hydrolysed, and these were mostly predicted to be located at turns on the protein surface. Bonds that were not cleaved in tetanus toxin were cleaved when presented in oligopeptides, sometimes faster than an equivalent oligopeptide based on a bond that was cleaved in the protein. Legumain cleaved the bait region of rat alpha1-macroglobulin and was 'trapped' by the macroglobulin, as most other endopeptidases are, but did not interact with human alpha2-macroglobulin, which contains no asparagine residue in its bait region. Glycosylation of asparagine totally prevented hydrolysis by legumain. Specificity for arylamide substrates was evaluated with reference to benzyloxycarbonyl-Ala-Ala-Asn-aminomethylcoumarin, and the preference for the P3-position amino acid was Ala>Tyr(tertiary butyl)>Val>Pro>Phe=Tyr>Leu=Gly. There was no hydrolysis of substrate analogues containing mono- or di-N-methylasparagines, l-2-amino-3-ureidopropionic acid or citrulline in the P1 position. We conclude that mammalian legumain appears to be totally restricted to the hydrolysis of asparaginyl bonds in substrates of all kinds. There seem to be no strong preferences for particular amino acids in other subsites, and yet there are still unidentified factors that prevent hydrolysis of many asparaginyl bonds in proteins.