A novel feature for monitoring the enzymatic harvesting process of adherent cell cultures based on lens-free imaging.

Adherent cell cultures are often dissociated from their culture vessel (and each other) through enzymatic harvesting, where the detachment response is monitored by an operator. However, this approach is lacking standardisation and reproducibility, and prolonged exposure or too high concentrations can affect the cell's viability and differentiation potential. Quantitative monitoring systems are required to characterise the cell detachment response and objectively determine the optimal time-point to inhibit the enzymatic reaction. State-of-the-art methodologies rely on bulky imaging systems and/or features (e.g. circularity) that lack robustness. In this study, lens-free imaging (LFI) technology was used to develop a novel cell detachment feature. Seven different donors were cultured and subsequently harvested with a (diluted) enzymatic harvesting solution after 3, 5 and 7 days of culture. Cell detachment was captured with the LFI set-up over a period of 20 min (every 20 s) and by optimising the reconstruction of the LFI intensity images, a new feature could be identified. Bright regions in the intensity image were identified as detaching cells and using image analysis, a method was developed to automatically extract this feature, defined as the percentage of detached cell regions. Next, the method was quantitatively and qualitatively validated on a diverse set of images. Average absolute error values of 1.49%, 1.34% and 1.97% were obtained for medium to high density and overconfluent cultures, respectively. The detachment response was quantified for all conditions and the optimal time for enzyme inhibition was reached when approximately 92.5% of the cells were detached. On average, inhibition times of 9.6-11.1 and 16.2-17.2 min were obtained for medium to high density and overconfluent cultures, respectively. In general, overconfluent cultures detached much slower, while their detachment rate was also decreased by the diluted harvesting solution. Moreover, several donors exhibited similar trends in cell detachment behaviour, with two clear outliers. Using the novel feature, measurements can be performed with an increased robustness, while the compact LFI design could pave the way for in situ monitoring in a variety of culture vessels, including bioreactors.

Simultaneous quantitation of sphingoid bases by UPLC-ESI-MS/MS with identical 13C-encoded internal standards.

Free sphingoid bases (lysosphingolipids) of primary storage sphingolipids are increased in tissues and plasma of several sphingolipidoses. As shown earlier by us, sphingoid bases can be accurately quantified using UPLC-ESI-MS/MS, particularly in combination with identical 13C-encoded internal standards. The feasibility of simultaneous quantitation of sphingoid bases in plasma specimens spiked with a mixture of such standards is here described. The sensitivity and linearity of detection is excellent for all examined sphingoid bases (sphingosine, sphinganine, hexosyl-sphingosine (glucosylsphingosine), hexosyl2-sphingosine (lactosylsphingosine), hexosyl3-sphingosine (globotriaosylsphingosine), phosphorylcholine-sphingosine) in the relevant concentration range and the measurements show very acceptable intra- and inter-assay variation (<10% average). Plasma samples of a series of male and female Gaucher Disease and Fabry Disease patients were analyzed with the multiplex assay. The obtained data compare well to those earlier determined for plasma globotriaosylsphingosine and glucosylsphingosine in GD and FD patients. The same approach can be also applied to measure sphingolipids in the same sample. Following extraction of sphingolipids from the same sample these can be converted to sphingoid bases by microwave exposure and subsequently quantified using 13C-encoded internal standards.

Heart rate time series characteristics for early detection of infections in critically ill patients.

It is difficult to make a distinction between inflammation and infection. Therefore, new strategies are required to allow accurate detection of infection. Here, we hypothesize that we can distinguish infected from non-infected ICU patients based on dynamic features of serum cytokine concentrations and heart rate time series. Serum cytokine profiles and heart rate time series of 39 patients were available for this study. The serum concentration of ten cytokines were measured using blood sampled every 10 min between 2100 and 0600 hours. Heart rate was recorded every minute. Ten metrics were used to extract features from these time series to obtain an accurate classification of infected patients. The predictive power of the metrics derived from the heart rate time series was investigated using decision tree analysis. Finally, logistic regression methods were used to examine whether classification performance improved with inclusion of features derived from the cytokine time series. The AUC of a decision tree based on two heart rate features was 0.88. The model had good calibration with 0.09 Hosmer-Lemeshow p value. There was no significant additional value of adding static cytokine levels or cytokine time series information to the generated decision tree model. The results suggest that heart rate is a better marker for infection than information captured by cytokine time series when the exact stage of infection is not known. The predictive value of (expensive) biomarkers should always be weighed against the routinely monitored data, and such biomarkers have to demonstrate added value.

Impact of obesity on taste receptor expression in extra-oral tissues: emphasis on hypothalamus and brainstem.

Sweet perception promotes food intake, whereas that of bitterness is inhibitory. Surprisingly, the expression of sweet G protein-coupled taste receptor (GPCTR) subunits (T1R2 and T1R3) and bitter GPCTRs (T2R116, T2R118, T2R138 and T2R104), as well as the α-subunits of the associated signalling complex (αGustducin, Gα14 and αTransducin), in oral and extra-oral tissues from lean and obese mice, remains poorly characterized. We focused on the impact of obesity on taste receptor expression in brain areas involved in energy homeostasis, namely the hypothalamus and brainstem. We demonstrate that many of the GPCTRs and α-subunits are co-expressed in these tissues and that obesity decreases expression of T1R3, T2R116, Gα14, αTrans and TRPM5. In vitro high levels of glucose caused a prominent down-regulation of T1R2 and Gα14 expression in cultured hypothalamic neuronal cells, leptin caused a transient down-regulation of T1R2 and T1R3 expression. Intriguingly, expression differences were also observed in other extra-oral tissues of lean and obese mice, most strikingly in the duodenum where obesity reduced the expression of most bitter and sweet receptors. In conclusion, obesity influences components of sweet and bitter taste sensing in the duodenum as well as regions of the mouse brain involved in energy homeostasis, including hypothalamus and brainstem.

Potential of UCHL1 as biomarker for destruction of pancreatic beta cells.

There is a clinical need for plasma tests for real-time detection of beta cell destruction, as surrogate endpoint in islet transplantation and immunoprevention trials in type 1 diabetes. This study reports on the use of label-free LC-MS/MS proteomics for bottom-up selection of candidate biomarkers. Ubiquitin COOH-terminal hydrolase 1 (UCHL1) was identified as abundant protein in rat and human beta cells, showing promising beta cell-selectivity, and was selected for further validation in standardized toxicity models. In vitro, H2O2-induced necrosis of INS-1 cells and human islets resulted in intracellular UCHL1 depletion and its extracellular discharge. In vivo, streptozotocin progressively depleted UCHL1 from islet cores and in 50% of animals, an associated plasma UCHL1 surge was detected preceding the GAD65 peak. UCHL1 was cleared with a half-life of 20min. Whole-body dynamic planar imaging of (99m)-Technetium-labeled UCHL1 indicated a rapid UCHL1 uptake in the liver and spleen, followed by urinary excretion of mainly proteolytic UCHL1 fragments. We conclude that LC-MS/MS proteomics is a useful tool to prioritize biomarkers for beta cell injury with promising molar abundance. Despite its consistent UCHL1 discharge by damaged beta cells in vitro, its in vivo use might be restrained by its rapid elimination from plasma. BIOLOGICAL SIGNIFICANCE: Our bottom-up LC-MS/MS proteomics represents a pragmatic approach to identify protein-type biomarkers of pancreatic beta cell injury. UCHL1 successfully passed sequential validation steps of beta cell-selectivity, antigenicity and toxic discharge in vitro. Whole-body dynamic planar imaging of radiolabeled recombinant UCHL1 indicated rapid clearance through the liver, spleen and urinary excretion of proteolytic fragments, likely explaining non-consistent detection in vivo. Integration of kinetic biomarker clearance studies in the a priori selection criteria is recommended before engaging in resource-intensive custom development of sensitive immunoassays for clinical translation.

Increased glucocerebrosidase expression and activity in preeclamptic placenta.

INTRODUCTION: Lysosomal glucosidase beta acid (GBA) deficiency is inherent to Gaucher disease, Parkinsonism and Lewy-body dementia. Increased GBA expression has never been associated with human disease. We describe increased GBA expression and activity in placenta from preeclamptic pregnancies. METHODS: 112 placenta biopsies were available for qPCR, analysis of GBA gene expression and activity. Microanalysis was performed on 20 placenta samples. Alternatively spliced placental GBA transcripts were cloned, expressed in HEK293 cells and analyzed by Western blot and activity assay. RESULTS: GBA is expressed in the syncytiotrophoblast layer of human placenta already at 5 weeks of gestation. We identified five novel GBA transcripts in placenta that enzymatically inactive when expressed in HEK293 cells. Both GBA RNA expression and enzymatic activity are upregulated in preeclamptic placenta. Microarray analysis of 20 placenta tissues identified 158 genes co-regulating with GBA expression and gene enrichment analysis highlights lysosomal function. In our micro-array data GBA expression does not correlate with FLT1 expression, currently the most powerful marker for preeclampsia. There are 89 transcripts that are negatively correlated with GBA expression of which BMP4 and TFEB are interesting as they are essential to early placenta function. DISCUSSION: Although very speculative, we hypothesize that increased GBA expression might relate to placentation through decreased BMP4 signaling or vascularization through downregulation of TFEB. Ceramide, the product of hydrolysis of glucosylceramide by GBA and involved in the regulation of cell differentiation, survival and apoptosis, is another putative candidate linking increased GBA activity to preeclampsia. Both pathways merit further investigation.

Value of plasma chitotriosidase to assess non-neuronopathic Gaucher disease severity and progression in the era of enzyme replacement therapy.

Gaucher disease (GD) is caused by deficiency of the enzyme glucocerebrosidase catalysing the regular lysosomal degradation of glucosylceramide. In the common non-neuropathic variant of GD, glucosylceramide-laden macrophages (Gaucher cells) accumulate in various tissues. Gaucher cells secrete chitotriosidase, an active chitinase, resulting in increased plasma chitotriosidase levels, which can be sensitively monitored by an enzyme activity assay. Plasma chitotriosidase is a rough estimate of body burden of Gaucher cells. Non-neuronopathic GD is presently treated by enzyme replacement therapy (ERT) and substrate reduction therapy (SRT). We addressed the question whether plasma chitotriosidase acts as (predictive) marker of clinical manifestations in non-neuronopathic GD patients receiving treatment. Reductions in plasma chitotriosidase during therapy correlated with corrections in liver and spleen volumes and showed positive trends with improvements in haemoglobin and platelet count and bone marrow composition. The occurrence of long-term complications and associated conditions such as multiple myeloma, bone complications, Parkinson's disease, hepatocellular carcinoma and pulmonary hypertension positively correlated with the plasma chitotriosidase level pre-therapy, the average plasma chitotriosidase during 3 years of ERT and the residual plasma chitotriosidase after 2 years of ERT. In summary, plasma chitotriosidase is a valuable marker in the assessment and follow-up of GD patients.

Model-based cell number quantification using online single-oxygen sensor data for tissue engineering perfusion bioreactors.

Online and non-invasive quantification of critical tissue engineering (TE) construct quality attributes in TE bioreactors is indispensable for the cost-effective up-scaling and automation of cellular construct manufacturing. However, appropriate monitoring techniques for cellular constructs in bioreactors are still lacking. This study presents a generic and robust approach to determine cell number and metabolic activity of cell-based TE constructs in perfusion bioreactors based on single oxygen sensor data in dynamic perfusion conditions. A data-based mechanistic modeling technique was used that is able to correlate the number of cells within the scaffold (R(2) = 0.80) and the metabolic activity of the cells (R(2) = 0.82) to the dynamics of the oxygen response to step changes in the perfusion rate. This generic non-destructive measurement technique is effective for a large range of cells, from as low as 1.0 × 10(5) cells to potentially multiple millions of cells, and can open-up new possibilities for effective bioprocess monitoring.

Functional characteristics of neonatal rat ß cells with distinct markers.

Neonatal ß cells are considered developmentally immature and hence less glucose responsive. To study the acquisition of mature glucose responsiveness, we compared glucose-regulated redox state, insulin synthesis, and secretion of ß cells purified from neonatal or 10-week-old rats with their transcriptomes and proteomes measured by oligonucleotide and LC-MS/MS profiling. Lower glucose responsiveness of neonatal ß cells was explained by two distinct properties: higher activity at low glucose and lower activity at high glucose. Basal hyperactivity was associated with higher NAD(P)H, a higher fraction of neonatal ß cells actively incorporating (3)H-tyrosine, and persistently increased insulin secretion below 5 mM glucose. Neonatal ß cells lacked the steep glucose-responsive NAD(P)H rise between 5 and 10 mM glucose characteristic for adult ß cells and accumulated less NAD(P)H at high glucose. They had twofold lower expression of malate/aspartate-NADH shuttle and most glycolytic enzymes. Genome-wide profiling situated neonatal ß cells at a developmental crossroad: they showed advanced endocrine differentiation when specifically analyzed for their mRNA/protein level of classical neuroendocrine markers. On the other hand, discrete neonatal ß cell subpopulations still expressed mRNAs/proteins typical for developing/proliferating tissues. One example, delta-like 1 homolog (DLK1) was used to investigate whether neonatal ß cells with basal hyperactivity corresponded to a more immature subset with high DLK1, but no association was found. In conclusion, the current study supports the importance of glycolytic NADH-shuttling in stimulus function coupling, presents basal hyperactivity as novel property of neonatal ß cells, and provides potential markers to recognize intercellular developmental differences in the endocrine pancreas.

Gaucher disease and Fabry disease: new markers and insights in pathophysiology for two distinct glycosphingolipidoses.

Gaucher disease (GD) and Fabry disease (FD) are two relatively common inherited glycosphingolipidoses caused by deficiencies in the lysosomal glycosidases glucocerebrosidase and alpha-galactosidase A, respectively. For both diseases enzyme supplementation is presently used as therapy. Cells and tissues of GD and FD patients are uniformly deficient in enzyme activity, but the two diseases markedly differ in cell types showing lysosomal accumulation of the glycosphingolipid substrates glucosylceramide and globotriaosylceramide, respectively. The clinical manifestation of Gaucher disease and Fabry disease is consequently entirely different and the response to enzyme therapy is only impressive in the case of GD patients. This review compares both glycosphingolipid storage disorders with respect to similarities and differences. Presented is an update on insights regarding pathophysiological mechanisms as well as recently available biochemical markers and diagnostic tools for both disorders. Special attention is paid to sphingoid bases of the primary storage lipids in both diseases. The value of elevated glucosylsphingosine in Gaucher disease and globotriaosylsphingosine in Fabry disease for diagnosis and monitoring of disease is discussed as well as the possible contribution of the sphingoid bases to (patho)physiology. This article is part of a Special Issue entitled New Frontiers in Sphingolipid Biology.

B cell lymphoma and myeloma in murine Gaucher's disease.

Multiple myeloma and B cell lymphoma are leading causes of death in Gaucher's disease but the nature of the stimulus driving the often noted clonal expansion of immunoglobulin-secreting B cells and cognate lymphoid malignancy is unknown. We investigated the long-term development of B cell malignancies in an authentic model of non-neuronopathic Gaucher's disease in mice: selective deficiency of ß-glucocerebrosidase in haematopoietic cells [Gba(tm1Karl/tm1Karl)Tg(Mx1-cre)1Cgn/0, with excision of exons 9-11 of the murine GBA1 gene, is induced by poly[I:C]. Mice with Gaucher's disease showed visceral storage of ß-glucosylceramide and greatly elevated plasma ß-glucosylsphingosine [median 57.9 (range 19.8-159) nm; n = 39] compared with control mice from the same strain [median 0.56 (range 0.04-1.38) nm; n = 29] (p < 0.0001). Sporadic fatal B cell lymphomas developed in 11 of 21 GD mice (6-24 months) but only two of eight control animals developed tumours by age 24 months. Unexpectedly, most mice with overt lymphoma had absent or few Gaucher cells but local inflammatory macrophages were present. Eleven of 39 of Gaucher mice developed monoclonal gammopathy, but in the control group only one animal of 25 had clonal immunoglobulin abnormalities. Seven of 10 of the B cell lymphomas were found to secrete a monoclonal paraprotein and the lymphomas stained intensely for pan-B cell markers; reactive T lymphocytes were also present in tumour tissue. In the Gaucher mouse strain, it was notable that, as in patients with this disease, CD138(+) plasma cells frequently surrounded splenic macrophages engorged with glycosphingolipid. Our strain of mice, with inducible deficiency of ß-glucocerebrosidase in haematopoietic cells and a high frequency of sporadic lethal B cell malignancies, faithfully recapitulates human Gaucher's disease: it serves as a tractable model to investigate the putative role of bioactive sphingolipids in the control of B cell proliferation and the pathogenesis of myelomatosis-the most prevalent human cancer associated with this disorder.

No difference in glycosphingolipid metabolism and mitochondrial function in glucocorticoid-induced insulin resistance in healthy men.

OBJECTIVE: Glucocorticoids (GCs) are well known to induce insulin resistance; however, mechanisms that cause the impairement of the insulin signaling pathway have not yet been identified. In this study we measured whether GC-induced insulin resistance in humans is related to changes in muscle ceramide, GM3, and muscle mitochondrial function. METHODS: In a randomized, placebo-controlled, double-blind, dose-response intervention study, 32 healthy males (aged 22 ± 3 years; body mass index 22.4 ± 1.7 kg/m(-2)) were allocated to prednisolone (PRED) 7.5 mg once daily (n = 12), PRED 30 mg once daily (n = 12), or placebo (n = 8) for 2 weeks using block randomization. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp before and after treatment. Muscle biopsies were performed to measure ceramide, monosialodihexosylganglioside (GM3), and mitochondrial function. RESULTS: Peripheral insulin sensitivity was dose dependently decreased after the PRED treatment. Muscle ceramide and GM3 concentration and mitochondrial function were not altered by 2 weeks of PRED treatment. CONCLUSION: Short-term GC treatment dose dependently impaired whole-body insulin sensitivity in healthy males, without concomitant changes in muscle ceramide, GM3, or mitochondrial function. These findings suggest that other mechanisms play a role in GC-related impairment of insulin sensitivity.

Model-based prediction of nephropathia epidemica outbreaks based on climatological and vegetation data and bank vole population dynamics.

Wildlife-originated zoonotic diseases in general are a major contributor to emerging infectious diseases. Hantaviruses more specifically cause thousands of human disease cases annually worldwide, while understanding and predicting human hantavirus epidemics pose numerous unsolved challenges. Nephropathia epidemica (NE) is a human infection caused by Puumala virus, which is naturally carried and shed by bank voles (Myodes glareolus). The objective of this study was to develop a method that allows model-based predicting 3 months ahead of the occurrence of NE epidemics. Two data sets were utilized to develop and test the models. These data sets were concerned with NE cases in Finland and Belgium. In this study, we selected the most relevant inputs from all the available data for use in a dynamic linear regression (DLR) model. The number of NE cases in Finland were modelled using data from 1996 to 2008. The NE cases were predicted based on the time series data of average monthly air temperature (°C) and bank voles' trapping index using a DLR model. The bank voles' trapping index data were interpolated using a related dynamic harmonic regression model (DHR). Here, the DLR and DHR models used time-varying parameters. Both the DHR and DLR models were based on a unified state-space estimation framework. For the Belgium case, no time series of the bank voles' population dynamics were available. Several studies, however, have suggested that the population of bank voles is related to the variation in seed production of beech and oak trees in Northern Europe. Therefore, the NE occurrence pattern in Belgium was predicted based on a DLR model by using remotely sensed phenology parameters of broad-leaved forests, together with the oak and beech seed categories and average monthly air temperature (°C) using data from 2001 to 2009. Our results suggest that even without any knowledge about hantavirus dynamics in the host population, the time variation in NE outbreaks in Finland could be predicted 3 months ahead with a 34% mean relative prediction error (MRPE). This took into account solely the population dynamics of the carrier species (bank voles). The time series analysis also revealed that climate change, as represented by the vegetation index, changes in forest phenology derived from satellite images and directly measured air temperature, may affect the mechanics of NE transmission. NE outbreaks in Belgium were predicted 3 months ahead with a 40% MRPE, based only on the climatological and vegetation data, in this case, without any knowledge of the bank vole's population dynamics. In this research, we demonstrated that NE outbreaks can be predicted using climate and vegetation data or the bank vole's population dynamics, by using dynamic data-based models with time-varying parameters. Such a predictive modelling approach might be used as a step towards the development of new tools for the prevention of future NE outbreaks.

Relating land cover and spatial distribution of nephropathia epidemica and Lyme borreliosis in Belgium.

Lyme borreliosis (LB) and nephropathia epidemica (NE) are zoonoses resulting from two different transmission mechanisms and the action of two different pathogens: the bacterium Borrelia burgdorferi and the Puumala virus, respectively. The landscape configuration is known to influence the spatial spread of both diseases by affecting vector demography and human exposure to infection. Yet, the connections between landscape and disease have rarely been quantified, thereby hampering the exploitation of land cover data sources to segment areas in function of risk. This study implemented a data-driven approach to relate land cover metrics and an indicator of NE/LB risk at different scales of observation of the landscape. Our results showed the suitability of the modeling approach (r² > 0.75, ρ < 0.001) and highlighted the relevance of the scale of observation in the set of landscape attributes found to influence disease risk as well as common and specific risk factors of NE and LB.

Taliglucerase alfa leads to favorable bone marrow responses in patients with type I Gaucher disease.

Taliglucerase alfa (Protalix Biotherapeutics, Israel) is a carrot-cell-expressed recombinant human beta-glucocerebrosidase recently approved in the United States for the treatment of type 1 Gaucher disease (GD). As bone disease is one of the most debilitating features of GD, quantification of bone marrow involvement is important for monitoring the response to treatment. Therefore, bone marrow fat fraction (Ff) measured by quantitative chemical shift imaging (QCSI) was included as exploratory parameter to evaluate bone marrow response in treatment naïve GD patients participating in a double-blind, randomized phase III study. Eight GD patients with intact spleens were treated with 30 or 60U/kg biweekly. Ff results were compared to outcomes in 15 untreated Dutch GD patients with a follow-up interval of 1year. Five taliglucerase alfa treated patients had a Ff below the threshold that relates to complication risk (<0.23) at baseline (median (n=8) 0.19, range 0.11-0.35). Ff significantly increased compared to baseline (p=0.012) and compared to untreated patients (p=0.005), already after 1year of follow-up with further improvement up to 36months. In four patients with the lowest Ff, the higher dose resulted in increases above 0.23 within 1year. All patients had sustained improvements in all other parameters. There was no influence of antibodies on response parameters. Treatment with taliglucerase alfa results in significant increases in lumbar spine fat fractions, which indicates clearance of Gaucher cells from the bone marrow.

Acid sphingomyelinase (Asm) deficiency patients in The Netherlands and Belgium: disease spectrum and natural course in attenuated patients.

Niemann-Pick disease (NPD) is a neurovisceral lysosomal storage disorder caused by acid sphingomyelinase (ASM) deficiency, which can be categorized as either Niemann-Pick disease type A [NPD-A], with progressive neurological disease and death in early childhood, or as Niemann-Pick disease type B [NPD-B], with a more variable spectrum of manifestations. Enzyme replacement therapy (ERT) with recombinant sphingomyelinase is currently studied as potential treatment for NPD-B patients. The objective of this study is to characterize the clinical features of patients with ASM deficiency in the Netherlands and Belgium with focus on the natural disease course of NPD-B patients. Prospective and retrospective data on ASM deficient patients were collected in The Netherlands and part of Belgium. Patients with NPD-B that could be followed prospectively were evaluated every 6-12 months for pulmonary function tests, 6 minute walk test (6 MWT), imaging (bone marrow infiltration measured by QCSI, organ volumes by MRI and CT scan of the lungs) and biochemical markers. Twenty-five patients with ASM deficiency were identified (13 males, 12 females, median age 13years, range 1-59 years). Nine patients had died at the time of the study, including four NPD-A patients at the age of 1,1, 2, 3 and five NPDB patents at the age of 5, 6, 43, 56 and 60 years. There was a high prevalence of homozygosity and compound heterozygosity for the common p.Arg608del mutation in 43% and 19% of NPD-B patients, respectively. In NPD-B patients, thrombocytopenia was present in most, while anemia and leucopenia were less common (33% and 6 % respectively). HDL cholesterol was reduced in most patients. Pulmonary disease was severe in several patients. Follow-up up to 11 years revealed a gradual decrease in platelet count. Detailed investigations in 6 NPD-B patients with follow-up in 4 patients revealed remarkable stable disease parameters up to 6 years, with some decline in pulmonary function and 6 MWT. Bone marrow fat fractions were decreased, indicating the presence of storage macrophages. Lung involvement was not related to the extent of visceromegaly, cytopenia or bone marrow involvement. In conclusion, in NPD-B patients pulmonary disease is the most debilitating feature. Disease manifestations are mostly stable in attenuated patients. Bone marrow infiltration is a less prominent feature of the disease.

Markers of bone turnover in Gaucher disease: modeling the evolution of bone disease.

CONTEXT: Gaucher disease (GD) is a lysosomal storage disorder characterized by abundant presence of macrophages. Bone complications and low bone density are believed to arise from enhanced bone resorption mediated through macrophage-derived factors. OBJECTIVE: The objective of the study was to investigate the relationship between bone turnover and bone complications in GD. DESIGN: This was a retrospective cohort study and review of the literature. PATIENTS: Forty adult type I GD patients were included in the study. OUTCOME MEASURES: Levels of the bone-resorption marker, type 1 collagen C-terminal telopeptide, and two bone-formation markers, N-terminal propeptide of type 1 procollagen and osteocalcin, were investigated in relation to clinical bone disease, measures of overall disease severity, and imaging data representing bone marrow infiltration. RESULTS: Osteocalcin was decreased in 50% of our patients (median 0.35 nmol/liter, normal 0.4-4.0), indicating a decrease of bone formation. Type 1 collagen C-terminal telopeptide and N-terminal propeptide of type 1 procollagen were within the normal range for most patients. Osteocalcin concentration was negatively correlated to measures of overall disease severity and positively correlated with imaging data (correlation coefficient 0.423; P = 0.025), suggesting a relation with disease severity. A review of the literature revealed variable outcomes on bone resorption markers but more consistent abnormalities in bone formation markers. Two of three reports conclude that bone-formation parameters increase in response to enzyme therapy, but none describes an effect on bone-resorption markers. CONCLUSIONS: In contrast to earlier hypotheses, we propose that in GD patients, primarily a decrease in bone formation causes an imbalance in bone remodeling.

A monozygotic twin pair with highly discordant Gaucher phenotypes.

We describe monozygotic twin sisters, born to consanguineous Moroccan parents, who are highly discordant for the manifestations of Gaucher disease. Both carry Gaucher genotype N188S/N188S. One has severe visceral involvement, epilepsy, and a cerebellar syndrome. Her twin does not manifest any symptoms or signs of Gaucher disease but suffers from type 1 diabetes mellitus. The concurrence of a mild Gaucher mutation with a severe phenotype, as well as the occurrence of highly discordant phenotypes in a pair of monozygotic twins, is discussed.