Development of a Multimodal, Physiotherapist-Led, Vocational Intervention for People with Inflammatory Arthritis and Reduced Work Ability: A Mixed-Methods Design Study.

PURPOSE: Work ability of people with rheumatoid arthritis (RA) and axial spondyloarthritis (axSpA) is reduced, but underexamined as a clinical treatment target. The evidence on vocational interventions indicates that delivery by a single healthcare professional (HCP) may be beneficial. Physiotherapist (PT)-led interventions have potential because PTs are most commonly consulted by RA/axSpA patients in the Netherlands. The aim was to develop a PT-led, vocational intervention for people with RA/axSpA and reduced work ability. METHODS: Mixed-methods design based on the Medical Research Council (MRC) framework for developing and evaluating complex interventions, combining a rapid literature review and six group meetings with: patient representatives (n = 6 and 10), PTs (n = 12), (occupational) HCPs (n = 9), researchers (n = 6) and a feasibility test in patients (n = 4) and PTs (n = 4). RESULTS: An intervention was developed and evaluated. Patient representatives emphasized the importance of PTs' expertise in rheumatic diseases and work ability. The potential for PTs to support patients was confirmed by PTs and HCPs. The feasibility test confirmed adequate feasibility and underlined necessity of training PTs in delivery. The final intervention comprised work-focussed modalities integrated into conventional PT treatment (10-21 sessions over 12 months), including a personalized work-roadmap to guide patients to other professionals, exercise therapy, patient education and optional modalities. CONCLUSION: A mixed-methods design with stakeholder involvement produced a PT-led, vocational intervention for people with RA/axSpA and reduced work ability, tested for feasibility and ready for effectiveness evaluation.

Effectiveness and cost-effectiveness of a multimodal, physiotherapist-led, vocational intervention in people with inflammatory arthritis: study protocol of the Physiotherapy WORKs trial.

BACKGROUND: Although reduced work ability is a substantial problem among people with inflammatory arthritis (IA), work ability is an underexposed area in clinical practice. Evidence on vocational interventions in IA is limited, but favourable results of delivery by a physiotherapist (PT) warrant the need for further research. Therefore, we aim to evaluate the (cost-)effectiveness of a multimodal, PT-led, vocational intervention in (self-)employed people with IA compared to usual care. METHODS: This randomized controlled trial will include 140 people with rheumatoid arthritis (RA) or axial spondyloarthritis (axSpA) who are (self-)employed and have reduced work ability (Work Ability Index - Single Item Scale (WAS) ≤ 7/10) and/or RA/axSpA related sick leave (≤ 6 months). Participants will be randomized 1:1 to the intervention or control condition (usual care). The intervention, delivered by primary care PTs, will be personalized to each patient, consisting of 10 to 21 sessions over 12 months. The intervention will be multimodal, comprising of 1) exercise therapy and a physical activity plan, 2) education/self-management support, 3) work-roadmap to guide participants in finding relevant other care, with optionally 4) online self-management course and 5) workplace examination. Assessments will be performed at baseline and after 3, 6, and 12 months. The primary outcome measure of effectiveness is work ability, as measured with the WAS at 12 months. For the cost-effectiveness analysis, the EuroQol (EQ-5D-5L), self-reported healthcare use, sick leave and productivity while at work will be used to estimate the trial based cost-utility from a societal perspective. A process evaluation, including assessments of adherence and treatment fidelity, will be undertaken using the registrations of the PTs and semi-structured interviews at 12 months follow-up in a random sample of the intervention group. DISCUSSION: The results of this study will provide insights in the (cost-)effectiveness of a multimodal, PT-led, vocational intervention in people with IA and a reduced work ability. TRIAL REGISTRATION: This study is registered in the International Clinical Trial Registry Platform (ICTRP) under number NL9343.

The use of PROMIS measures in clinical studies in patients with inflammatory arthritis: a systematic review.

PURPOSE: Although the use of Patient-Reported Outcomes Measurement Information System (PROMIS) measures is widely advocated, little is known on their use in patients with inflammatory arthritis. We systematically describe the use and outcomes of PROMIS measures in clinical studies involving people with rheumatoid arthritis (RA) or axial spondyloarthritis (axSpA). METHODS: A systematic review was conducted according to the PRISMA guidelines. Through a systematic search of nine electronic databases, clinical studies including patients with RA or axSpA and reporting the use of PROMIS measure were selected. Study characteristics, details of PROMIS measures and their outcomes, if available, were extracted. RESULTS: In total, 29 studies described in 40 articles met the inclusion criteria, of which 25 studies included RA patients, three studies included axSpA patients and one study included both RA and axSpA patients. The use of two general PROMIS measures (PROMIS Global Health, PROMIS-29) and 13 different domain-specific PROMIS measures was reported, of which the PROMIS Pain Interference (n = 17), Physical Function (n = 14), Fatigue (n = 13), and Depression (n = 12) measures were most frequently used. Twenty-one studies reported their results in terms of T-scores. Most T-scores were worse than the general population mean, indicating impairments of health status. Eight studies did not report actual data but rather measurement properties of the PROMIS measures. CONCLUSION: There was considerable variety regarding the different PROMIS measures used, with the PROMIS Pain interference, Physical function, Fatigue, and Depression measures being the most frequently used. In order to facilitate the comparisons across studies, more standardization of the selection of PROMIS measures is needed.

Implementing enhancements in supervised group exercise for people with axial spondyloarthritis: a hybrid effectiveness-implementation study.

OBJECTIVES: The content of supervised group exercise (SGE) for axial spondyloarthritis (axSpA) has hardly changed in recent decades, despite new evidence-based insights to improve SGE quality. This pilot implementation study evaluated the effects and feasibility of enhancements in axSpA-specific SGE in four regions in the Netherlands. METHOD: The implemented enhancements included: more high-intensity aerobic exercise; exercise personalization with periodic assessments; and patient education on home exercise. The implementation strategy included a one-day supervisor training course and telephone support. To evaluate effects, aerobic capacity [Six-Minute Walk Test (6MWT)], physical functioning [Ankylosing Spondylitis Performance-based Improvement (ASPI); improved/not improved], health status [Assessment of SpondyloArthritis international Society Health Index (ASAS HI) questionnaire], and home exercise engagement [Short QUestionnaire to ASsess Health-enhancing physical activity (SQUASH)] were assessed at baseline and after one year in 60 participants. Changes were analysed with the Wilcoxon signed-rank test. To evaluate feasibility, a survey of participants and semi-structured interviews with four SGE supervisors assessed uptake and satisfaction with the enhancements. RESULTS: Aerobic capacity increased significantly and 35% of participants improved functioning, whereas health status and home exercise engagement did not change. The participants' survey and supervisors' interviews showed that high-intensity aerobic exercise was implemented successfully, exercise personalization and periodic assessments were implemented partially, and patient education was not implemented at all. Most participants were satisfied with the changes. CONCLUSIONS: After this pilot implementation, SGE enhancements were only partially implemented. Nevertheless, aerobic capacity improved significantly and satisfaction with accomplished changes was high. Nationwide implementation would require adaptations to improve feasibility.

Reporting quality of interventions using a wearable activity tracker to improve physical activity in patients with inflammatory arthritis or osteoarthritis: a systematic review.

To assess the reporting quality of interventions aiming at promoting physical activity (PA) using a wearable activity tracker (WAT) in patients with inflammatory arthritis (IA) or hip/knee osteoarthritis (OA). A systematic search was performed in eight databases (including PubMed, Embase and Cochrane Library) for studies published between 2000 and 2022. Two reviewers independently selected studies and extracted data on study characteristics and the reporting of the PA intervention using a WAT using the Consensus on Exercise Reporting Template (CERT) (12 items) and Consolidated Standards of Reporting Trials (CONSORT) E-Health checklist (16 items). The reporting quality of each study was expressed as a percentage of reported items of the total CERT and CONSORT E-Health (50% or less = poor; 51-79% = moderate; and 80-100% = good reporting quality). Sixteen studies were included; three involved patients with IA and 13 with OA. Reporting quality was poor in 6/16 studies and moderate in 10/16 studies, according to the CERT and poor in 8/16 and moderate in 8/16 studies following the CONSORT E-Health checklist. Poorly reported checklist items included: the description of decision rule(s) for determining progression and the starting level, the number of adverse events and how adherence or fidelity was assessed. In clinical trials on PA interventions using a WAT in patients with IA or OA, the reporting quality of delivery process is moderate to poor. The poor reporting quality of the progression and tailoring of the PA programs makes replication difficult. Improvements in reporting quality are necessary.

The ASAS-OMERACT core domain set for axial spondyloarthritis.

BACKGROUND: The current core outcome set for ankylosing spondylitis (AS) has had only minor adaptations since its development 20 years ago. Considering the significant advances in this field during the preceding decades, an update of this core set is necessary. OBJECTIVE: To update the ASAS-OMERACT core outcome set for AS into the ASAS-OMERACT core outcome set for axial spondyloarthritis (axSpA). METHODS: Following OMERACT and COMET guidelines, an international working group representing key stakeholders (patients, rheumatologists, health professionals, pharmaceutical industry and drug regulatory agency representatives) defined the core domain set for axSpA. The development process consisted of: i) Identifying candidate domains using a systematic literature review and qualitative studies; ii) Selection of the most relevant domains for different stakeholders through a 3-round Delphi survey involving axSpA patients and axSpA experts; iii) Consensus and voting by ASAS; iv) Endorsement by OMERACT. Two scenarios are considered based on the type of therapy investigated in the trial: symptom modifying therapies and disease modifying therapies. RESULTS: The updated core outcome set for axSpA includes 7 mandatory domains for all trials (disease activity, pain, morning stiffness, fatigue, physical function, overall functioning and health, and adverse events including death). There are 3 additional domains (extra-musculoskeletal manifestations, peripheral manifestations and structural damage) that are mandatory for disease modifying therapies and important but optional for symptom modifying therapies. Finally, 3 other domains (spinal mobility, sleep, and work and employment) are defined as important but optional domains for all trials. CONCLUSION: The ASAS-OMERACT core domain set for AS has been updated into the ASAS-OMERACT core domain set for axSpA. The next step is the selection of instruments for each domain.

The importance of international collaboration for rare diseases research: a European perspective.

Over the last two decades, important contributions were made at national, European and international levels to foster collaboration into rare diseases research. The European Union (EU) has put much effort into funding rare diseases research, encouraging national funding organizations to collaborate together in the E-Rare program, setting up European Reference Networks for rare diseases and complex conditions, and initiating the International Rare Diseases Research Consortium (IRDiRC) together with the National Institutes of Health in the USA. Co-ordination of the activities of funding agencies, academic researchers, companies, regulatory bodies, and patient advocacy organizations and partnerships with, for example, the European Research Infrastructures maximizes the collective impact of global investments in rare diseases research. This contributes to accelerating progress, for example, in faster diagnosis through enhanced discovery of causative genes, better understanding of natural history of rare diseases through creation of common registries and databases and boosting of innovative therapeutic approaches. Several examples of funded pre-clinical and clinical gene therapy projects show that integration of multinational and multidisciplinary expertize generates new knowledge and can result in multicentre gene therapy trials. International collaboration in rare diseases research is key to improve the life of people living with a rare disease.

Sustained therapeutic effects of oral miglustat (Zavesca, N-butyldeoxynojirimycin, OGT 918) in type I Gaucher disease.

It has been shown that treatment with miglustat (Zavesca, N-butyldeoxynojirimycin, OGT 918) improves key clinical features of type I Gaucher disease after 1 year of treatment. This study reports longer-term efficacy and safety data. Patients who had completed 12 months of treatment with open-label miglustat (100-300 mg three times daily) were enrolled to continue with therapy in an extension study. Data are presented up to month 36. Liver and spleen volumes measured by CT or MRI were scheduled every 6 months. Biochemical and haematological parameters, including chitotriosidase activity (a sensitive marker of Gaucher disease activity) were monitored every 3 months. Safety data were also collected every 3 months. Eighteen of 22 eligible patients at four centres entered the extension phase and 14 of these completed 36 months of treatment with miglustat. After 36 months, there were statistically significant improvements in all major efficacy endpoints. Liver and spleen organ volumes were reduced by 18% and 30%, respectively. In patients whose haemoglobin value had been below 11.5 g/dl at baseline, mean haemoglobin increased progressively from baseline by 0.55 g/dl at month 12 (NS), 1.28 g/dl at month 24 (p =0.007), and 1.30 g/dl at month 36 (p =0.013). The mean platelet count at month 36 increased from baseline by 22 x 10(9)/L. No new cases of peripheral neuropathy occurred since previously reported. Diarrhoea and weight loss, which were frequently reported during the initial 12-month study, decreased in magnitude and prevalence during the second and third years. Patients treated with miglustat for 3 years show significant improvements in organ volumes and haematological parameters. In conclusion, miglustat was increasingly effective over time and showed acceptable tolerability in patients who continued with treatment for 3 years.

Inhibition of substrate synthesis as a strategy for glycolipid lysosomal storage disease therapy.

The glycosphingolipid (GSL) lysosomal storage diseases are caused by mutations in the genes encoding the glycohydrolases that catabolize GSLs within lysosomes. In these diseases the substrate for the defective enzyme accumulates in the lysosome and the stored GSL leads to cellular dysfunction and disease. The diseases frequently have a progressive neurodegenerative course. The therapeutic options for treating these diseases are relatively limited, and for the majority there are no effective therapies. The problem is further compounded by difficulties in delivering therapeutic agents to the brain. Most research effort to date has focused on strategies for augmenting enzyme levels to compensate for the underlying defect. These include bone marrow transplantation (BMT), enzyme replacement and gene therapy. An alternative strategy that we have been exploring is substrate deprivation. This approach aims to balance the rate of GSL synthesis with the impaired rate of GSL breakdown. The imino sugar N-butyldeoxynojirimycin (NB-DNJ) inhibits the first step in GSL biosynthesis and has been used to evaluate this approach. Studies in an asymptomatic mouse model of Tay-Sachs disease have shown that substrate deprivation prevents GSL storage in the CNS. In a severe neurodegenerative mouse model of Sandhoff disease, substrate deprivation delayed the onset of symptoms and disease progression and significantly increased life expectancy. Combining NB-DNJ and BMT was found to be synergistic in the Sandhoff mouse model. A clinical trial in type I Gaucher disease has been undertaken and has shown beneficial effects. Efficacy was demonstrated on the basis of significant decreases in liver and spleen volumes, gradual but significant improvement in haematological parameters and disease activity markers, together with diminished GSL biosynthesis and storage as determined by independent biochemical assays. Further trials in type I Gaucher disease are in progress; studies are planned in patients with GSL storage in the CNS.

The facile detection of 1505G-->A in Gaucher patients with different phenotypes.

In Gaucher disease patients, over 100 disease-causing mutations have been identified. For identification of the 1504C-->T (R463C) mutation it is common to use PCR-restriction fragmentation analysis using the restriction enzyme MspI. In the present study we investigated the reliability of this approach because accurate determination of genotypes is important in genotype-phenotype correlations. A simple modification, i.e. using the restriction enzyme HphI instead of MspI, revealed that type I and II Gaucher disease patients who had previously been identified as carrying the 1504C-->T mutation in fact carried the 1505G-->A (IVS10(-1)G-->A) mutation. Sequencing of the appropriate fragment confirmed this. The PCR method easily differentiates between these two mutations in Gaucher disease patients, thus circumventing the need for sequencing procedures. The phenotypes of the patients found to be carrying the 1505G-->A mutation are also described.

Novel oral treatment of Gaucher's disease with N-butyldeoxynojirimycin (OGT 918) to decrease substrate biosynthesis.

BACKGROUND: Current treatment for Gaucher's disease involves administration of intravenous glucocerebrosidase to degrade glucocerebroside stored in lysosomes. Lowering the rate of biosynthesis of glucocerebroside should decrease accumulation of this substrate. We investigated the safety and efficacy of OGT 918 (N-butyldeoxynojirimycin), an inhibitor of glucosyltransferase, as a novel oral treatment for non-neuronopathic Gaucher's disease. METHODS: We recruited, into a 1-year open-label study, 28 adults (seven with previous splenectomies) from four national Gaucher's referral clinics, who were unable or unwilling to receive enzyme treatment. We measured liver and spleen volume by computed tomography or magnetic resonance imaging at baseline and at months 6 and 12, and biochemical and haematological variables monthly, including chitotriosidase activity (a sensitive marker of Gaucher's disease activity). Patients were started on 100 mg oral OGT 918 three times daily. FINDINGS: Baseline liver volumes were 1.1-2.7 times normal and spleen volumes 5.1-24.8 times normal. At 12 months, mean liver and spleen volumes were significantly lowered by 12% (95% CI 7.8-16.4) and 19% (14.3-23.7), respectively (each p<0.001). Haematological variables improved slightly. Mean organ volume and blood counts improved continually between 6 months and 12 months of treatment. Mean chitotriosidase concentrations fell by 16.4% over 12 months (p<.0001). Six patients withdrew because of gastrointestinal complaints (two), personal reasons (two), or severe pre-existing disease (two). The most frequent adverse effect was diarrhoea, which occurred in 79% of patients shortly after the start of treatment. INTERPRETATION: Decrease of substrate formation by OGT 918 improves key clinical features of non-neuronopathic Gaucher's disease. The strategy justifies further trials in this and other glycosphingolipid storage disorders.

Hepatosplenomegalic lipidosis: what unless Gaucher? Adult cholesteryl ester storage disease (CESD) with anemia, mesenteric lipodystrophy, increased plasma chitotriosidase activity and a homozygous lysosomal acid lipase -1 exon 8 splice junction mutation.

A 36-year-old woman was admitted for hepatosplenomegaly and anemia. Bone marrow cytology showed "sea-blue histiocytes", vacuolated macrophages and plasma cells. As primary liver disease, malignancy or hematologic disorders were excluded, and plasma chitotriosidase activity was increased 27-fold over control, the presence of a lysosomal storage disease was suspected. Biochemical analysis of skin fibroblasts revealed normal glucocerebrosidase and sphingomyelinase activity, but lipid analysis showed a more than 15-fold accumulation of cholesterol esters within the cells. The activity of lysosomal acid lipase (LAL) in fibroblast homogenates was decreased to 12% of control subjects. Mutational analysis of the patient's blood showed the homozygous G-->A mutation at position -1 of the exon 8 splice donor site (E8SJM-allele) known for adult cholesteryl ester storage disease (CESD); the polymorphic background was that of the complex haplotype -6Thr, 2Gly, 894 G-->A. Based on clinical, laboratory, cytological and and biochemical findings, CESD can clearly be separated from other more frequent inherited lysosomal storage diseases, e.g. atypical forms of Gaucher disease.

The frequency of lysosomal storage diseases in The Netherlands.

We have calculated the relative frequency and the birth prevalence of lysosomal storage diseases (LSDs) in The Netherlands based on all 963 enzymatically confirmed cases diagnosed during the period 1970-1996. The combined birth prevalence for all LSDs is 14 per 100,000 live births. Glycogenosis type II is the most frequent LSD with a birth prevalence of 2.0 per 100,000 live births, representing 17% of all diagnosed cases. Within the group of lipidoses, metachromatic leukodystrophy (MLD) is the most frequent LSD. MLD was diagnosed in 24% of lipidoses and the calculated birth prevalence was 1.42 per 100,000 for all types combined. Krabbe disease, diagnosed in 17% of cases, also belongs to the more frequent lipid storage diseases in The Netherlands with a birth prevalence of 1.35 per 100,000. The birth prevalence of Gaucher disease, commonly regarded as the most frequent lipid storage disease is 1.16 per 100,000 for all types combined. The combined birth prevalence for all lipid storage diseases is 6.2 per 100,000 live births. Within the group of mucopolysaccharidoses (MPSs), MPS I has the highest calculated birth prevalence of 1.19 per 100,000 (25% of all cases of MPS diagnosed), which is slightly more frequent than MPS IIIA with an estimated birth prevalence of 1.16 per 100,000. As a group, MPS III comprises 47% of all MPS cases diagnosed and the combined birth prevalence is 1.89 per 100,000 live births. The birth prevalence of MPS II is 0.67 per 100,000 (1.30 per 100,000 male live births). All other MPSs are rare. The combined birth prevalence for all MPSs is 4.5 per 100,000 live births. Mucolipidoses and oligosaccharidoses are very rare with birth prevalences between 0.04 and 0.20 for individual diseases. Only 49 cases were diagnosed between 1970 and 1996. Their combined birth prevalence is 1.0 per 100,000 live births.

Oligosaccharide excretion in adult Gaucher disease.

Gaucher disease is a lysosomal storage disease characterized by storage of glucocerebroside due to lysosomal glucocerebrosidase deficiency. Increased urinary excretion of sialyloligosaccharides and mannosylglycoasparagines has been described for two patients with the infantile form of the disease, probably as a consequence of obstruction of lysosomal functioning due to the glycolipid accumulation in lysosomes. By thin-layer chromatography, we found increased urinary oligosaccharide excretion in a series of adult non-neuronopathic patients. Oligosaccharide patterns were comparable between patients and also with the pattern observed in infantile Gaucher disease. Composition was analysed by methanolysis and gas chromatography. Mannose and N-acetylglucosamine are the main carbohydrates in all oligosaccharide bands. A statistically significant correlation was found between oligosaccharide excretion and the severity of the disease expressed as severity score index. Patients treated with enzyme replacement therapy showed a reduction up to 65% of the original oligosaccharide excretion after 1 year of treatment, comparable with the reduction in spleen volume.

Glucocerebrosidase genotype of Gaucher patients in The Netherlands: limitations in prognostic value.

Gaucher disease is a recessively inherited lysosomal storage disorder that is caused by a deficiency in glucocerebrosidase activity. The clinical expression is markedly heterogeneous with respect to age of onset, progression, severity, and neurological involvement. The relative incidence of glucocerebrosidase (GC) mutations has been studied extensively for Jewish but not for non-Jewish Caucasian patient populations. The present survey on mutant GC genotypes prevalent in Gaucher disease in The Netherlands was taken of 72 patients from different genetic backgrounds. This number is more than half the total number of affected Gaucher patients to be expected on the basis of the incidence of the disorder in this country. Analysis of nine GC mutations led to the identification of 74% of the mutant GC alleles in patients from 44 unrelated Dutch families (i.e., families that have lived in The Netherlands for at least several generations) and of 44% of the mutant GC alleles in patients from nine unrelated families that recently immigrated from both European and non-European countries. The N370S (cDNA 1226G) GC mutation proved to occur most frequently (41%) in the unrelated Dutch patients and less frequently (6%) in the unrelated immigrant patients and was always associated with the nonneuronopathic (Type 1) form of the disease. Apart from the association of the N370S mutation with Type 1 Gaucher disease, the prognostic value of GC genotyping was limited, since a particular GC genotype did not correlate closely to a specific clinical course, or to a specific relative responsiveness to enzyme-supplementation therapy.

Plasma tumor necrosis factor-a (TNF-a) levels in Gaucher disease.

Tumor necrosis factor-a (TNF-a) levels were measured in the plasma of patients with different types of Gaucher disease (GD) and patients with other lysosomal storage diseases. The highest TNF-a levels were observed in the most severe neuronopathic type of GD, exceeding those found in healthy individuals as well as patients with other lysosomal disorders. Type I GD cases showed a wide range of TNF-a levels ranging from normal to 2.5 x the highest control value. TNF-a is a pleiotropic cytokine produced mainly by activated macrophages. Our data suggest that it may play a role in the pathophysiology of GD disease.

Quantitative analysis of the targeting of mannose-terminal glucocerebrosidase. Predominant uptake by liver endothelial cells.

Gaucher's disease is an inherited lysosomal storage disorder that is caused by a deficiency of glucocerebrosidase. The resulting accumulation of the substrate glucosylceramide in macrophages of liver, spleen, and bone marrow causes severe clinical symptoms. Gaucher's disease is treated by intravenous administration of a modified glucocerebrosidase (Alglucerase), which has exposed mannose residues to promote uptake by target macrophages. To evaluate the effectiveness of the targeting of Alglucerase, we studied the fate of the enzyme in the rat. Intravenously injected Alglucerase was rapidly cleared from the circulation (half-life 2.0 +/- 0.5 min). The liver was the main site of uptake, with 65.6 +/- 1.2% of the dose present at 10 min after injection. Smaller amounts ( < 3% of the dose) were taken up by spleen and bone marrow. Previous injection with mannan substantially increased the plasma half-life of the enzyme (14.8 +/- 3.2 min versus 1.7 +/- 0.3 min in solvent-preinjected controls) and uptake of the enzyme by liver, spleen and bone marrow was reduced by > 90%. These findings indicate that the enzyme is taken up by these organs via mannose-specific receptors. Subcellular fractionation of the liver indicated that the enzyme is internalized and transported to the lysosomes. By isolating various liver cell types after injection of the Alglucerase, it was found that endothelial cells are the main site of uptake of the enzyme: 60.8 +/- 3.4% of the total liver uptake. Parenchymal and Kupffer cells were responsible for 31.0 +/- 3.1% and 8.2 +/- 0.7% of the hepatic uptake, respectively. We conclude that Alglucerase is rapidly cleared from the circulation by mannose-specific receptors in liver, spleen, and bone marrow. However, less than 10% of the enzyme taken up by the liver is accounted for by Kupffer cells, the hepatic target cells for therapeutic intervention. It is suggested that alterations of the formulation of the therapeutic enzyme may lead to a higher uptake by Kupffer cells and other macrophages, and thus to a more (cost)effective therapy of Gaucher's disease.

Individualised low-dose alglucerase therapy for type 1 Gaucher's disease.

Previous studies have shown that enzyme supplementation therapy with alglucerase for type 1 Gaucher's disease is effective at doses of 30-130 U/kg per month. Since both the clinical presentation and the response to therapy in Gaucher's disease are highly variable, individual dosing seems indicated. This notion, as well as the high costs of alglucerase and the unknown long-term side-effects, led us to investigate the efficacy of an individualised very low dose of alglucerase. Twenty-five adults with symptomatic type 1 Gaucher's disease (thirteen splenectomised) received alglucerase 1.15 U/kg three times a week (15 U/kg per month). Every 6 months, the dose was halved, maintained, or doubled, according to the response (based on haematological variables and liver and spleen volume). After 6 months of treatment, eighteen (72%) patients had a response (seventeen moderate, one good). After 12 months (in nineteen patients) and 18 months (in seven patients), all had sustained improvement. Severe splenomegaly resulted in slower haematological responses. Our results are similar to those obtained by others with higher-dose regimens and better than a low-dose regimen of 10U/kg every 2 weeks. We conclude that very low initial doses of alglucerase, when administered frequently, are effective and cost-saving in the treatment of type 1 Gaucher's disease.

Characterization of glucocerebrosidase in Greek Gaucher disease patients: mutation analysis and biochemical studies.

Gaucher disease is the most frequent lysosomal storage disease in Greece, accounting for 24% of all lysosomal disorders diagnosed during the last 13 years at the Institute of Child Health in Athens. The nature of the defects in glucocerebrosidase in Greek Gaucher patients with non-neuronopathic (type 1) and neuronopathic (types 2 and 3) phenotypes was investigated at the level of the glucocerebrosidase gene and enzyme activity. Mutation analysis performed in 10/23 Gaucher patients with different types of the disorder led to the identification of four mutations, N370S, L444P, R463C and D409H, comprising 75% of the investigated alleles. N370S was only found in association with type 1 disease. The genotype D409H/R463C was identified for the first time and was associated with the severe type 2 disorder. There was no correlation between residual in vitro enzyme activity and either phenotype or genotype. However, in cultured fibroblast of the neuronopathic cases, glucocerebrosidase protein concentration was reduced and the capacity to degrade exogenous C6NBD-glucosylceramide was more severely impaired.