Biochemical assessment of Paget's disease of bone

Effect of intestinal microbiota on duck short-beak and dwarf syndrome caused by novel goose parvovirus

Short-beak and dwarf syndrome (SBDS) is caused by infection with novel goose parvovirus (NGPV), which leads to intestinal dysbiosis, developmental delay, short beak, lameness, and paralysis in ducks and is the cause of skeletal health problems. NGPV infection can cause intestinal microbial disturbances, but it is still unclear whether the intestinal microbiota affects the pathogenicity of NGPV. Here, the effects of intestinal microbiota on NGPV-induced SBDS in Cherry Valley ducks were assessed by establishing a duck model for gut microflora depletion/reestablishment through antibiotics (ABX) treatment/fecal microbiota transplanted (FMT). By measuring body weight, beak length, beak width and tarsal length, we found that SBDS clinical symptoms were alleviated in ducks treated with ABX, but not in FMT ducks. Next, we conducted a comprehensive analysis of bone metabolism, gut barrier integrity, and inflammation levels using quantitative real-time PCR (qPCR), enzyme linked immunosorbent assay (ELISA), biochemical analysis and histological analysis. The results showed that ABX treatment improved bone quality reduced bone resorption, mitigated tissue lesions, protected intestinal barrier integrity, and inhibited systemic inflammation in NGPV-infected ducks. Moreover, cecal microflora composition and short-chain fatty acids (SCFAs) production were examined by bacterial 16S rRNA sequencing and gas chromatography. The results revealed that ABX treatment mitigated the decreased abundance of Firmicutes and Bacteroidota in NGPV-infected ducks, as well as increased SCFAs production. Furthermore, ABX treatment reduced the mucosa-associated lymphoid tissue lymphoma translocation protein 1 (Malt1) and nuclear factor κB (NF-κB) expression, which are correlated with systemic inflammation in SBDS ducks. These findings suggested that intestinal microflora depletion alleviated NGPV-induced SBDS by maintaining intestinal homeostasis, inhibiting inflammatory response and alleviating bone resorption. These results provide evidence for the pivotal role of intestinal microbiota in the process of SBDS and contribute a theoretical basis for the feasibility of microecological preparation as a method to control SBDS.

Bone scan findings of Paget's disease of bone in patients with VCP Multisystem Proteinopathy 1

Multisystem Proteinopathy 1 (MSP1) disease is a rare genetic disorder caused by mutations in the Valosin-Containing Protein (VCP) gene with clinical features of inclusion body myopathy (IBM), frontotemporal dementia (FTD), and Paget's disease of bone (PDB). We performed bone scan imaging in twelve patients (6 females, 6 males) with confirmed VCP gene mutation six (50%) of which has myopathy alone, four (33%) with both PDB and myopathy, and two (15%) were presymptomatic carriers. We aim to characterize the PDB in diagnosed individuals, and potentially identify PDB in the myopathy and presymptomatic groups. Interestingly, two patients with previously undiagnosed PDB had positive diagnostic findings on the bone scan and subsequent radiograph imaging. Among the individuals with PDB, increased radiotracer uptake of the affected bones were of typical distribution as seen in conventional PDB and those reported in other MSP1 cohorts which are the thoracic spine and ribs (75%), pelvis (75%), shoulder (75%) and calvarium (15%). Overall, we show that technetium-99m bone scans done at regular intervals are a sensitive screening tool in patients with MSP1 associated VCP variants at risk for PDB. However, diagnostic confirmation should be coupled with clinical history, biochemical analysis, and skeletal radiographs to facilitate early treatment and prevention complications, acknowledging its limited specificity.

Rolling circle transcription/G-quadruplex/QnMorpholine probe for highly selective and sensitive detection of alkaline phosphatase activity

In this study, we combined a rolling circle transcription (RCT) system producing 22AG G-quadruplex RNA with a QnMorpholine (QNM) fluorescent probe for the selective and sensitive detection of alkaline phosphatase (ALP). ALP is involved in various biological functions, with monophosphate cleavage being one of its characteristic properties. Here, we developed a padlock RCT probing system in which a large amount of RCT 22AG RNA G-quadruplex was produced in the absence of ALP, providing a high fluorescence signal. In contrast, no RNA G-quadruplex was produced in the presence of ALP, with minimal fluorescence. This huge deviation in signal intensity allowed us to identify the presence or absence of ALP in a test sample. Under practical conditions, our system allowed the differentiation for ALP even when it was present at an extremely low concentration (0.0085 U/L), along with very high specificity. The simplicity and efficiency of this approach for ALP detection suggest its potential for use as a reliable diagnostic tool.

Artroplastia total de cadera en paciente con enfermedad de Paget: presentación de un caso

Introducción: La enfermedad de Paget es un trastorno metabólico de etiología desconocida, secundario a un incremento en la función de los osteoclastos y la consecuente respuesta de los osteoblastos a la formación exagerada de hueso. Compromete con mayor frecuencia el fémur proximal y, a menudo, se diagnostica incidentalmente. Se presenta el caso de una mujer con antecedente de enfermedad de Paget y pseudoartrosis de cadera izquierda, con indicaciones de prótesis total de cadera izquierda y un episodio único de luxación, sin complicaciones posteriores y una adecuada evolución. Conclusión: El manejo quirúrgico en casos de fractura de cadera permite restablecer la marcha y mejorar la calidad de vida de los pacientes con enfermedad de Paget. A pesar de ser una patología que dificulta el manejo de los pacientes, la enfermedad de Paget no es una contraindicación para la artroplastia total de cadera y permite mejorar el dolor y recuperar la funcionalidad

Updates on Paget's Disease of Bone

Paget's disease of the bone is a prevalent bone disease characterized by disorganized bone remodeling; however, it is comparatively uncommon in East Asian countries, including China, Japan, and Korea. The exact cause still remains unknown. In genetically susceptible individuals, environmental triggers such as paramyxoviral infections are likely to cause the disease. Increased osteoclast activity results in increased bone resorption, which attracts osteoblasts and generates new bone matrix. Fast bone resorption and formation lead to the development of disorganized bone tissue. Increasing serum alkaline phosphatase or unique radiographic lesions may serve as the diagnostic indicators. Common symptoms include bone pain, bowing of the long bones, an enlarged skull, and hearing loss. The diagnosis is frequently confirmed by radiographic and nuclear scintigraphy of the bone. Further, bisphosphonates such as zoledronic acid and pamidronate are effective for its treatment. Moreover, biochemical monitoring is superior to the symptoms as a recurrence indicator. This article discusses the updates of Paget's disease of bone with a clinical case.

Drug Repurposing: An Emerging Tool for Drug Reuse, Recycling and Discovery

Drug repositioning or repurposing is a revolutionary breakthrough in drug development that focuses on rediscovering new uses for old therapeutic agents. Drug repositioning can be defined more precisely as the process of exploring new indications for an already approved drug while drug repurposing includes overall re-development approaches grounded in the identical chemical structure of the active drug moiety as in the original product. The repositioning approach accelerates the drug development process, curtails the cost and risk inherent to drug development. The strategy focuses on the polypharmacology of drugs to unlocks novel opportunities for logically designing more efficient therapeutic agents for unmet medical disorders. Drug repositioning also expresses certain regulatory challenges that hamper its further utilization. The review outlines the eminent role of drug repositioning in new drug discovery, methods to predict the molecular targets of a drug molecule, advantages that the strategy offers to the pharmaceutical industries, explaining how the industrial collaborations with academics can assist in the discovering more repositioning opportunities. The focus of the review is to highlight the latest applications of drug repositioning in various disorders. The review also includes a comparison of old and new therapeutic uses of repurposed drugs, assessing their novel mechanisms of action and pharmacological effects in the management of various disorders. Various restrictions and challenges that repurposed drugs come across during their development and regulatory phases are also highlighted.

Increased frequency of impaired fasting glucose and isolated systolic hypertension in Paget's disease of bone

PURPOSE

Scanty data about glucose metabolism and hypertension have been reported in Paget's disease of bone (PDB) to be related with increased cardiovascular mortality. The aim of the present study was to evaluate glucose and blood pressure levels in PDB, looking for their association with disease severity.

METHODS

We performed an observational cross-sectional study in 54 patients with PDB and 54 age, sex and BMI-matched controls. Glucose and blood pressure levels and parameters of bone and mineral metabolism were assessed.

RESULTS

Patients with PDB showed increased glucose levels (6.3 ± 1.7 vs 5.3 ± 1.4 mmol/l, p < 0.001) and prevalence of impaired fasting glucose (14.8%, 5.3-24.3 vs 1.9%, 0-5.4, p < 0.02) as well as enhanced systolic blood pressure (145.9 ± 21.3 vs 132.9 ± 18.9 mmHg, p < 0.005), pulse pressure (69.6 ± 20.0 vs 56.0 ± 16.9 mmHg, p < 0.01) and prevalence of isolated systolic hypertension (46.3%, 33.0-59.6 vs 16.7%, 6.7-26.6, p < 0.003) in comparison to controls. Moreover, we found a positive association of (1) glucose levels with ionized calcium and bone alkaline phosphatase; (2) both systolic and pulse pressure with total and bone alkaline phosphatase (p < 0.05). By multiple linear regression analysis (R² = 0.26; p < 0.05) serum ionized calcium correlated with glucose levels (β = 0.44; p < 0.04), after adjusting for age and BMI.

CONCLUSIONS

Our study shows increased fasting glucose, systolic and pulse pressure levels as well as enhanced prevalence of impaired fasting glucose and isolated systolic hypertension in PDB, potentially accounting for increased cardiovascular mortality. Furthermore, our findings suggest high serum calcium and/or increased bone alkaline phosphatase as a link between PDB and cardio-metabolic disorders.

Paget's Disease of Bone: Diagnosis and Treatment

Paget's disease of bone is a common bone disorder characterized by disorganized bone remodeling. The most likely etiology is a slow paramyxoviral infection in genetically susceptible individuals; however, the exact cause is unknown. Enhanced bone resorption due to an increased activity of osteoclasts recruits numerous osteoblasts to resorption sites, with large quantities of new bone matrix produced as a result. The accelerated bone resorption and formation are not as closely coupled as in a healthy bone; a disorganized bone tissue is formed. Many patients are asymptomatic; rising serum alkaline phosphatase or incidental finding of characteristic radiographic lesions are often the only diagnostic clues. Common clinical manifestations include bone pain, bowing of long bones, enlarged skull, and hearing loss. An elevated serum alkaline phosphatase level correlates with the disease activity. The diagnosis is confirmed by characteristic radiographic findings and by nuclear scintigraphy of the bone (the most sensitive test). Bisphosphonates, such as zoledronic acid, pamidronate, alendronate, and risedronate, are the mainstay of treatment. Patients who do not tolerate bisphosphonates can be treated with calcitonin.

First Chemosensor for Selective Detection and Quantification of L-4-Hydroxyproline in Collagen and Other Bio Samples

Amino pyridine-based rhodamine conjugate (APR) has been developed as a first chemosensor for selective detection and quantification of L-4-Hydroxyproline (Hyp). The "turn-on" fluorescence property of the chemosensor makes it unique for easy estimation of Hyp in collagen and biological samples.

Familial Early-Onset Paget's Disease of Bone Associated with a Novel hnRNPA2B1 Mutation

Paget disease of bone (PDB) is a common metabolic bone disease characterized by increased bone resorption and disorganized bone formation which affect single or multiple sites of bones. Although the exact cause of PDB is still controversial, genetic factors are considered to play an important role in PDB. Several genes involved in the differentiation or function of osteoclast were shown to be associated with PDB or related syndrome such as SQSTM1, TNFRSF11A, TNFRSF11B, and ZNF687. Multisystem proteinopathy (MSP), a newly proposed syndrome including inclusion body myopathy (IBM), PDB, frontotemporal dementia (FTD), and amyotrophic lateral sclerosis (ALS), is mainly caused by mutation in VCP gene. In 2013, a new casual gene for MSP was identified as hnRNPA2B1 gene. This may partly account for the inherited PDB traits which is however negative for mutation in already known causative PDB genes. We investigated a Chinese family with multiple affected individuals with PDB, but none of the members showed symptoms of IBM, FTD, or ALS. Three patients were evaluated clinically, biochemically, and radiographically. To screen for the responsible mutation, whole-exome sequencing was conducted in the proband, another patient, as well as a normal individual from the family. This revealed a novel heterozygous missense mutation of hnRNPA2B1 gene (c.929C>T, p. P310L) in the two patients which was then verified in all affected individuals. We describe here a novel missense mutation in hnRNPA2B1 gene in a large pedigree affected with PDB with members who do not present other manifestations of multisystem proteinopathy, such as IBM, FTD, and ALS.

Computer-assisted quantitative evaluation of bisphosphonate treatment for Paget's disease of bone using the bone scan index

The purpose of the present study was to analyze the effect of treatment of Paget's disease of bone (PDB) with bone scintigraphy using a computer-assisted diagnosis system (BONENAVI) that quantitatively evaluates bone metabolism. Seven patients with PDB (three male, four female; average age, 60 years; age range, 33–80 years) underwent bone scintigraphy and measurement of serum alkaline phosphatase (ALP), bone-specific ALP (BAP), serum cross-linked N-telopeptide (NTx) of type I collagen, urinary NTx, and deoxypyridinoline (DPD) before and after bisphosphonate treatment. Bone scan index (BSI), artificial neural network (ANN) value, and hotspot number (HSn) were calculated using BONENAVI software. Mean follow-up period was 22 months (range, 11–35 months). Among three BONENAVI parameters (ANN, BSI, and HSn), only BSI was significantly lower after bisphosphonate treatment as compared with before. All bone metabolic markers excluding DPD were significantly lower following bisphosphonate treatment than before. Bone formation markers (ALP and BAP) were significantly lower than bone resorption markers (U-NTx and S-NTx). The correlation of BONENAVI parameters with four bone metabolic markers was analyzed before and after bisphosphonate treatment. Before treatment, the majority of the four markers did not correlate with the BONENAVI parameters. In contrast, post-treatment ALP, BAP, and U-NTx were significantly correlated with BSI and HSn. To the best of our knowledge, this is the first study to evaluate the treatment of PDB by bone scintigraphy using a computer-assisted diagnosis system that quantitatively evaluates bone metabolism. The findings demonstrated that, using BONENAVI software, bone scintigraphy is able to quantitatively and spatially evaluate the bisphosphonate treatment effect, particularly in patients with polyostotic PDB.

Paget's disease of bone-genetic and environmental factors

Paget's disease of bone is generally diagnosed in individuals aged >50 years, usually manifests in one or several bones and is initiated by osteoclast-induced osteolytic lesions. Subsequently, over a period of many years, osteoblastic activity can result in sclerosis and deformation of bone. The prevalence of Paget's disease is highest in the UK and in countries where a large number of residents have ancestors from the UK. Currently, in many countries, the prevalence of the disorder has decreased. A considerable number of affected patients have a family history of Paget's disease and the disorder has an autosomal dominant pattern of inheritance but with incomplete penetrance. A large number of mutations in SQSTM1 (which encodes sequestosome-1; also known as ubiquitin-binding protein p62) seem to account for the susceptibility to develop Paget's disease in some families; the involvement of other genes is currently under investigation. In addition to a genetic cause, environmental factors have been proposed to have a role in the pathogenesis of Paget's disease. Although most evidence has been presented for measles virus as an aetiologic factor, some studies have not confirmed its involvement. The decreasing incidence of Paget's disease, which could be attributed to measles vaccination along with the measles virus nucleocapsid protein induction of Paget's disease lesions in transgenic mice, supports an aetiologic role of the virus.

Bone resorption in kidney transplant recipients

Early diagnosis of persistent hyperparathyroidism (HP) following kidney transplantation may prevent worsening of osteodystrophy and potential damage to the graft. We evaluated the utility of collagen pyridinoline (PYD) and deoxypyridinoline (DPD) urinary cross-links beyond the common HP markers to evaluate 70 selected stable recipients between 1997 and 2006 who were divided into 2 group depending on the immunosuppressive protocol. All patients showed elevated levels of urinary cross-links even though calcemia and phosphoremia values were normal. Their mean creatinine level was slightly increased. Data were assessed as mean values +/- SD. All variables underwent a correlation matrix analysis and a stepwise regression, with posttransplant intact parathyroid hormone (iPTH) as the dependent variable and other variables as regressors. A statistically significant correlation was observed between PYD and alkaline phosphatase (ALP; P = .0026, r = .41); PYD and DPD (P = .015, r = .34); pre- and posttransplant iPTH (P = .024, r = .31); and creatinine and ALP (P = .024, r = .31). Taking the groups separately, there were significant correlations between PYD and ALP (P = .0076, r = .42); PYD and DPD (P = .017, r = .38); ALP and posttransplant iPTH (P = .038, r = .33); osteocalcin (OC) and posttransplant iPTH (P = .048, r = .32); and pre- and posttransplant iPTH (P = .019, r = .37) among subjects in the first group, whereas subjects in the second group showed a correlation between posttransplant iPTH and age at transplantation (P = .032, r = .61). In conclusion, we showed that urinary cross-links may be helpful to reveal bone resorption in kidney recipients when usual bone metabolism parameters do not demonstrate hyperparathyroidism.

Bone turnover markers in Paget's disease of the bone: A Systematic review and meta-analysis

The aim of this systematic review and meta-analysis is to study the utility of the commonly used bone turnover markers in evaluating disease activity in patients with Paget's disease of bone before and after treatment with bisphosphonates. We found good correlation between the bone turnover marker concentrations and disease activity assessed by bone scintigraphy.

INTRODUCTION

Paget's disease of bone is a common skeletal disorder of the elderly. Bone turnover marker concentrations are used for diagnosis and follow-up. We aimed to compare the available bone turnover markers and determine their utility in assessing disease activity when compared to quantitative bone scintigraphy.

METHODS

We conducted a systematic review and meta-analysis searching MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Scopus. We evaluated total alkaline phosphatase (total ALP), bone-specific alkaline phosphatase (bone ALP), procollagen type 1 amino-terminal propeptide (P1NP), serum, and urine C-terminal telopeptide (uCTx and sCTx, respectively), and urine N-terminal telopeptide (uNTx). The main outcome of interest was the correlation of disease activity with concentrations of bone turnover markers in Paget's disease patients before and after treatment with bisphosphonates. Correlation coefficients were pooled across studies using the random effects model.

RESULTS

We included 17 observational studies and one trial reporting on 953 patients. Prior to treatment, all studied bone turnover markers had moderate to strong correlation with scintigraphic indices (correlation coefficients ranging from 0.58 to 0.80) with no statistically significant difference between the bone turnover markers overall (p = 0.08). P1NP, uNTx, and bone ALP tend to have higher correlation with scintigraphy. After starting treatment with bisphosphonate, there was moderate to strong correlation with disease activity with all markers except bone ALP (correlation coefficients ranging from 0.43 to 0.70).

CONCLUSION

The findings of this meta-analysis suggest the Paget's disease activity is best monitored by following P1NP levels. However, total ALP, bone ALP, and uNTx are good alternatives as markers of disease activity in untreated patients. Total ALP and uNTx can be useful in following patients with Paget's disease after treatment if P1NP is not available. Clinicians, however, should take availability, cost, and the presence of liver disease into consideration when deciding which bone turnover marker is most appropriate when evaluating patients with Paget's disease.

Modifications to nano- and microstructural quality and the effects on mechanical integrity in Paget's disease of bone

Paget's disease of bone (PDB) is the second most common bone disease mostly developing after 50 years of age at one or more localized skeletal sites; it is associated with severely high bone turnover, bone enlargement, bowing/deformity, cracking, and pain. Here, to specifically address the origins of the deteriorated mechanical integrity, we use a cohort of control and PDB human biopsies to investigate multiscale architectural and compositional modifications to the bone structure (ie, bone quality) and relate these changes to mechanical property measurements to provide further insight into the clinical manifestations (ie, deformities and bowing) and fracture risk caused by PDB. Here, at the level of the collagen and mineral (ie, nanometer-length scale), we find a 19% lower mineral content and lower carbonate-to-phosphate ratio in PDB, which accounts for the 14% lower stiffness and 19% lower hardness promoting plastic deformation in pathological bone. At the microstructural scale, trabecular regions are known to become densified, whereas cortical bone loses its characteristic parallel-aligned osteonal pattern, which is replaced with a mosaic of lamellar and woven bone. Although we find this loss of anisotropic alignment produces a straighter crack path in mechanically-loaded PDB cases, cortical fracture toughness appears to be maintained due to increased plastic deformation. Clearly, the altered quality of the bone structure in PDB affects the mechanical integrity leading to complications such as bowing, deformities, and stable cracks called fissure fractures associated with this disease. Although the lower mineralization and loss of aligned Haversian structures do produce a lower modulus tissue, which is susceptible to deformities, our results indicate that the higher levels of plasticity may compensate for the lost microstructural features and maintain the resistance to crack growth.

Paget's disease of bone

Paget's disease is an osteoclastic-mediated disorder of bone that results in abnormal bone resorption associated with inadequate remodeling that leads to mechanically weakened bone. Demonstrating variable geographic prevalence, it is becoming less frequent and age of onset is lengthening in areas of once high prevalence prior to the institution of effective medical therapies, suggesting its etiology involves both environmental as well as genetic factors. Insights into its pathophysiology are helping to clarify other inherited osteolytic disorders of bone by providing additional insights into related cellular processes.

Genetic association study of UCMA/GRP and OPTN genes (PDB6 locus) with Paget's disease of bone

We performed a genetic association study of rare variants and single nucleotide polymorphisms (SNPs) of UCMA/GRP and OPTN genes, in French-Canadian patients with Paget's disease of bone (PDB) and in healthy controls from the same population. We reproduced the variant found in the UCMA/GRP basal promoter and tested its functionality using in vitro transient transfection assays. Interestingly, this SNP rs17152980 appears to affect the transcription level of UCMA/GRP. In addition, we have identified five rare genetic variants in UCMA/GRP gene, four of them being population-specific, although none were found to be associated with PDB. Six Tag SNPs of UCMA/GRP gene were associated with PDB, particularly the SNP rs17152980 (uncorrected P=3.8 × 10(-3)), although not significant after Bonferroni's correction. More importantly, we replicated the strong and statistically significant genetic association of two SNPs of the OPTN gene, the rs1561570 (uncorrected P=5.7 × 10(-7)) and the rs2095388 (uncorrected P=4.9 × 10(-3)), with PDB. In addition, we identified a very rare variant found to be located close to the basal promoter of the OPTN gene, at -232bp from its distal transcription start site. Furthermore, depending on the type of allele present (G or A), the binding of several important nuclear factors such as the vitamin D or the retinoic acid receptors is predicted to be altered at this position, suggesting a significant effect in the regulation of transcription of the OPTN gene. In conclusion, we identified a functional SNP located in the basal promoter of the UCMA/GRP gene which provided a weak genetic association with PDB. In addition, we replicated the strong genetic association of two already known SNPs of the OPTN gene, with PDB in a founder effect population. We also identified a very rare variant in the promoter of OPTN, and through bioinformatic analysis, identified putative transcription factor binding sites likely to affect OPTN gene transcription.

Asymptomatic Paget's bone disease in ethnic Thais: a series of four case reports and a review of the literature

Paget's bone disease is quite common in some parts of Europe and countries inhabited by European emigrants, but it is rare in Asia. There have been only 13 reported cases in Southeast Asia, including one reported case from Thailand. Half of the previously reported cases had bone symptoms and the other half were asymptomatic, but were incidentally discovered when patients were being investigated for other medical problems. Here are reported cases of four asymptomatic patients who presented elevation of serum alkaline phosphatase during routine annual medical checkups. All patients were of Chinese descent and all cases were proven by biopsy. Based on this experience, we are of the opinion that a substantial number of unrecognized cases of Paget's disease exist among ethnic Thais. We feel that they would be revealed if clinicians were alerted of its presence and if they included it as a possible diagnosis together with metastasis and osteoporosis when examining bone lesions or when results for elevated serum alkaline phosphatase are detected during routine checkups. We also anticipate that a higher prevalence of this disease may occur in future Thai generations due to the addition of offspring from Asian-European intermarriages to offspring of Chinese descent in the ethnic Thai population.

Emerging strategies and therapies for treatment of Paget's disease of bone

Paget's disease of bone (PDB) is a progressive monostotic or polyostotic metabolic bone disease characterized by focal abnormal bone remodeling, with increased bone resorption and excessive, disorganized, new bone formation. PDB rarely occurs before middle age, and it is the second most frequent metabolic bone disorder after osteoporosis, affecting up to 3% of adults over 55 years of age. One of the most striking and intriguing clinical features is the focal nature of the disorder, in that once the disease is established within a bone, there is only local spread within that bone and no systemic dissemination. Despite many years of intense research, the etiology of PDB has still to be conclusively determined. Based on a detailed review of genetic and viral factors incriminated in PDB, we propose a unifying hypothesis from which we can suggest emerging strategies and therapies. PDB results in weakened bone strength and abnormal bone architecture, leading to pain, deformity or, depending on the bone involved, fracture in the affected bone. The diagnostic assessment includes serum total alkaline phosphatase, total body bone scintigraphy, skull and enlarged view pelvis x-rays, and if needed, additional x-rays. The ideal therapeutic option would eliminate bone pain, normalize serum total alkaline phosphatase with prolonged remission, heal radiographic osteolytic lesions, restore normal lamellar bone, and prevent recurrence and complications. With the development of increasingly potent bisphosphonates, culminating in the introduction of a single intravenous infusion of zoledronic acid 5 mg, these goals of treatment are close to being achieved, together with long-term remission in almost all patients. Based on the recent pathophysiological findings, emerging strategies and therapies are reviewed: ie, pulse treatment with zoledronic acid; denosumab, a fully human monoclonal antibody directed against RANK ligand; tocilizumab, an interleukin-6 receptor inhibitor; odanacatib, a cathepsin K inhibitor; and proteasome and Dickkopf-1 inhibitors.

Profound hypocalcemia following effective response to zoledronic acid treatment in a patient with juvenile Paget's disease

Juvenile Paget's disease (JPD) is a rare, autosomal recessive osteopathy. Although it has phenotypic overlap with Paget's disease of bone (PDB), it is probably a distinct entity. Because of its rarity, optimal disease management has not yet been established by randomized controlled trials. However, clinical, biochemical, and radiographic improvement has been reported after treatment with antiresorptive agents, including calcitonin and bisphosphonates (BPs). Compared with other BPs, zoledronic acid (ZOL) has a higher affinity to bone mineral and is a stronger inhibitor of the enzyme farnesyl pyrophosphate synthase (the main target of nitrogen-containing BPs), properties that explain the prolonged effect of ZOL on bone turnover and render it a therapeutic option for JPD, similar to PDB. We describe hereby, for the first time in the literature, the case of a patient with JPD who developed severe hypocalcemia and secondary hyperparathyroidism following effective treatment with ZOL.

Circulating and tissue-derived isoforms of bone alkaline phosphatase in Paget's disease of bone

BACKGROUND

Alkaline phosphatase (ALP) is routinely used in the assessment of Paget's disease of bone (PDB); however, the individual bone ALP isoforms (B/I, B1, and B2) have not been investigated in this disorder.

METHODS

Subjects comprised 37 patients (mean age 74 years) with symptomatic PDB confirmed by radiograph and stratified into high and low total ALP activity groups and 66 healthy individuals (mean age 64 years). Extracts of human cancellous and cortical bone tissues were also investigated. The bone ALP isoforms, measured by HPLC, were compared with two bone ALP immunoassays (Metra and Ostase), and the bone formation marker intact amino-terminal procollagen type I propeptide (iPINP).

RESULTS

All bone ALP isoforms were increased in high ALP activity PDB compared with the low ALP activity and control groups (p < 0.0001). The B2 isoform had the greater relative activity representing 36%, 50%, and 71%, of the total ALP activity in the control, low and high ALP activity groups, respectively. Compared with controls, B2 was increased in the low ALP activity PDB group (p < 0.05). ROC analysis showed a validity of approximately 80% for B2 to discriminate patients with PDB.

CONCLUSION

All bone ALP isoforms were increased in patients with high ALP activity PDB and the B2 isoform was even elevated in the low ALP activity PDB group. The bone ALP isoform B2 may be of use in the management of PDB but that has to be further elucidated in subsequent studies.

Five-year follow-up of Japanese patients with Paget's disease of the bone after treatment with low-dose oral alendronate: a case series

INTRODUCTION

Paget's disease of the bone is characterized by focal abnormalities of increased bone turnover affecting one or more sites throughout the skeleton. Although this disease is rare in Japan, it is common in western and southern Europe, and among British migrants in Australia and New Zealand. Bisphosphonates have been widely used for the treatment of Paget's disease of the bone and are considered to be the treatment of choice. However, there have been few reports on the long-term follow-up examination of patients after their treatment with bisphosphonates.

CASE PRESENTATION

We report the treatment with a low dose of oral alendronate (5 mg per day) which was effective in reducing bone turnover and pain over the five-year follow-up period in two Japanese patients, a 66-year-old man and a 68-year-old woman, with Paget's disease of the bone. Furthermore, in one patient, no clinical symptoms, such as bone pain or increases in serum total alkaline phosphatase and urinary N-terminal telopeptide of type I collagen as markers of bone turnover, were observed over the patient's five-year follow-up period.

CONCLUSIONS

To the best of our knowledge, this is the first report of a long-term follow-up of patients with Paget's disease of the bone after a six-month treatment with low-dose oral alendronate (5 mg per day).

Paget's disease of bone: emphasis on treatment with zoledronic acid

The treatment of Paget's disease of bone (PDB) aims at suppression of abnormal bone turnover and bisphosphonates (BPs) are currently the drugs of choice. Zoledronic acid, a third-generation nitrogen-containing BPs, is the newest BP approved for PDB and is administered by a single intravenous infusion. In vitro zoledronic acid has higher binding affinity for hydroxyapatite and is a stronger inhibitor of farnesyl pyrophosphate synthase compared with other BPs. In vivo zoledronic acid improves symptoms, normalizes bone turnover markers and scintigraphic imaging in the majority of patients, and maintains remission of PDB longer than other BPs. This review summarizes available data on the pathogenesis, epidemiology, clinical manifestation, biochemical assessment and management of PDB, giving special attention to the treatment of PDB with zoledronic acid, based on current evidence.

Epidemiology and genetic epidemiology of the liver function test proteins

Background

The liver function test (LFT) is among the most commonly used clinical investigations to assess hepatic function, severity of liver diseases and the effect of therapies, as well as to detect drug-induced liver injury (DILI).

Aims

To determine the relative contribution of genetic and environmental factors as well as test and quantify the effects of sex, age, BMI and alcohol consumption to variation in liver function test proteins - including alanine amino transaminase (ALT), Albumin, gamma glutamyl transpeptidase (GGT), total bilirubin, total protein, total globulin, aspartate transaminase (AST), and alkaline phosphotase (ALP) - using the classical twin model.

Methods

Blood samples were collected from a total of 5380 twin pairs from the TwinsUK registry. We measured the expression levels of major proteins associated with the LFT, calculated BMI from measured weight and height and questionnaires were completed for alcohol consumption by the twins. The relative contribution of genetic and environmental factors to variation in the LFT proteins was assessed and quantified using a variance components model fitting approach.

Results

Our results show that (1) variation in all the LFTs has a significant heritable basis (h² ranging from 20% to 77%); (2) other than GGT, the LFTs are all affected to some extent by common environmental factors (c² ranging from 24% to 54%); and (3) a small but significant proportion of the variation in the LFTs was due to confounding effects of age, sex, BMI, and alcohol use.

Conclusions

Variation in the LFT proteins is under significant genetic and common environmental control although sex, alcohol use, age and BMI also contribute significantly to inter-individual variation in the LFT proteins. Understanding the underlying genetic contribution of liver function tests may help the interpretation of their results and explain wide variation among individuals.

Management of patients with Paget's disease: a consensus document of the Belgian Bone Club

Paget's disease of bone (PDB) is a potentially crippling condition. Pain, fracture, spinal stenosis, nerve entrapment, vascular steal syndrome, secondary osteoarthritis, bone deformity, dental problems, deafness, excessive bleeding during orthopaedic surgery, rare sarcomatous degeneration, and hypercalcaemia constitute complications that may impair the quality of life. The therapeutic approach varies from symptomatic (analgesics, anti-inflammatory drugs) to more specific drugs such as increasingly potent bisphosphonates. Studies such as the PRISM study should in the future help to determine the superiority or not of aggressive treatment over symptomatic treatment in the prevention of complications. Various oral and/or intravenous (i.v.) bisphosphonates have been tested and are currently on the market. The most recently available nitrogen-containing bisphosphonate, i.v. zoledronic acid, is the most potent therapy available for the treatment of PDB. Its therapeutic efficacy, its long-term effect on biologic activity and its good tolerance currently supports its use as a first-line therapeutic option in patients suffering from PDB.

The amino- and carboxyterminal cross-linked telopeptides of collagen type I, NTX-I and CTX-I: a comparative review

Bone diseases such as osteoporosis or bone metastases are a continuously growing problem in the ageing populations across the world. In recent years, great efforts have been made to develop specific and sensitive biochemical markers of bone turnover that could help in the assessment and monitoring of bone turnover. The amino- and carboxyterminal cross-linked telopeptides of type I collagen (NTX-I and CTX-I, respectively) are two widely used bone resorption markers that attracted great attention due to their relatively high sensitivity and specificity for the degradation of type I collagen, and their rapid adaptation to automated analyzers. However, the clinical performance of both markers differs significantly depending on the clinical situation. These differences have caused considerable confusion and uncertainty. If used correctly, both markers have great potential to improve the management of many bone diseases. We here review the biochemistry, analytical background and clinical performance of NTX-I and CTX-I, as documented in the accessible literature until March 2008.