Syndromes with congenital brittle bones

Aggregation of human osteoblasts unlocks self-reliant differentiation and constitutes a microenvironment for 3D-co-cultivation with other bone marrow cells

Skeletal bone function relies on both cells and cellular niches, which, when combined, provide guiding cues for the control of differentiation and remodeling processes. Here, we propose an in vitro 3D model based on human fetal osteoblasts, which eases the study of osteocyte commitment in vitro and thus provides a means to examine the influences of biomaterials, substances or cells on the regulation of these processes. Aggregates were formed from human fetal osteoblasts (hFOB1.19) and cultivated under proliferative, adipo- and osteoinductive conditions. When cultivated under osteoinductive conditions, the vitality of the aggregates was compromised, the expression levels of the mineralization-related gene DMP1 and the amount of calcification and matrix deposition were lower, and the growth of the spheroids stalled. However, within spheres under growth conditions without specific supplements, self-organization processes occur, which promote extracellular calcium deposition, and osteocyte-like cells develop. Long-term cultivated hFOB aggregates were free of necrotic areas. Moreover, hFOB aggregates cultivated under standard proliferative conditions supported the co-cultivation of human monocytes, microvascular endothelial cells and stromal cells. Overall, the model presented here comprises a self-organizing and easily accessible 3D osteoblast model for studying bone marrow formation and in vitro remodeling and thus provides a means to test druggable molecular pathways with the potential to promote life-long bone formation and remodeling.

Imaging of Congenital Skeletal Disorders

Osteochondrodysplasias are the result of the expression of gene mutations. The phenotypes in osteochondrodysplasias evolve through life, with the possibility that previously unaffected bones may be involved at later stages of growth. Due to the variable time of onset, the diagnosis may be made prenatally, at birth, or later. Certainty in the diagnosis is sometimes only achieved as the patient matures and the disease evolves. Radiographic evaluation is a fundamental part of the diagnostic work-up of congenital skeletal disorders and in most cases the first tool used to arrive at a diagnosis. This review describes the imaging characteristics, specific signs, and evolution of several skeletal dysplasias in which diagnosis may be directly or indirectly suggested by radiologic findings. A definitive accurate diagnosis of a congenital skeletal abnormality is necessary to help provide a prognosis of expected outcomes and to counsel parents and patients.

Osteogenesis imperfecta: treatment and surgical management

PURPOSE OF REVIEW

Osteogenesis imperfecta is a disease with many different causes and clinical presentations. Surgery at a young age is the often required in order to improve the patients' growth development and quality of life. This manuscript highlights the current approach to treat children with osteogenesis imperfecta. The main purpose of this review is to compare and discuss the latest surgical techniques and procedures.

RECENT FINDINGS

Recent studies have indicated that telescoping intramedullary Faisser-Duval rods are one of the most suitable surgical devices to correct long bone deformities. The design permits elongation with growth and helps reduce the number of revision surgeries compared to previous static devices.

SUMMARY

Osteogenesis imperfecta patients require an interdisciplinary and tailored treatment that involves both medical and surgical components. On the basis of the most recent surgical and medical findings, the authors recommend treating osteogenesis imperfecta patients early with bisphosphonates prior to surgical intervention and then utilizing Faisser-Duval rods in a surgical setting to correct lower extremity deformities and fractures.

Therapeutic Dimensions of Bisphosphonates: A Clinical Update

Bisphosphonates (BPs) are a commonly used class of drugs for the treatment of bone disorders. An extensive review of BPs with their clinical efficacy and safety profile is unavailable. This study aimed to review the available literature on BPs, summarize their role in clinical therapy, and emphasize their safety profile. Authors reviewed the existing literature using the Google Scholar, PubMed, and Micromedex databases and analyzed the collected articles. BPs are the preferred medication for osteoporosis and other similar conditions owing to their efficient antiosteoclastic activity. Few of them are available in oral dosage forms; hence, they are patient-friendly. The mechanism of action, common adverse effects and their clinical applications, precautions and warnings pertaining to the route of administration, and safety profiles have been discussed in this manuscript. The common adverse effects are majorly related to the gastrointestinal, cardiovascular, and endocrine system. Upon chronic usage, patients may experience serious problems like osteonecrosis of the jaw and atypical bone fractures. Although BPs are effective and safe, they may cause GI adverse effects and rare cases of osteonecrosis. Patient counseling could prove beneficial in early identification and prevention of the adverse effects associated with BPs.

Molecular alterations in the extracellular matrix in the brains of newborns with congenital Zika syndrome

Zika virus (ZIKV) infection during pregnancy can cause a set of severe abnormalities in the fetus known as congenital Zika syndrome (CZS). Experiments with animal models and in vitro systems have substantially contributed to our understanding of the pathophysiology of ZIKV infection. Here, to investigate the molecular basis of CZS in humans, we used a systems biology approach to integrate transcriptomic, proteomic, and genomic data from the postmortem brains of neonates with CZS. We observed that collagens were greatly reduced in expression in CZS brains at both the RNA and protein levels and that neonates with CZS had several single-nucleotide polymorphisms in collagen-encoding genes that are associated with osteogenesis imperfecta and arthrogryposis. These findings were validated by immunohistochemistry and comparative analysis of collagen abundance in ZIKV-infected and uninfected samples. In addition, we showed a ZIKV-dependent increase in the expression of cell adhesion factors that are essential for neurite outgrowth and axon guidance, findings that are consistent with the neuronal migration defects observed in CZS. Together, these findings provide insights into the underlying molecular alterations in the ZIKV-infected brain and reveal host genes associated with CZS susceptibility.

Identification of a Candidate Mutation in the COL1A2 Gene of a Chow Chow With Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a genetic disease that occurs in humans and animals. Individuals with OI exhibit signs of extreme bone fragility and osteopenia with frequent fractures and perinatal lethality in severe cases. In this study, we report the clinical diagnosis of OI in a dog and the use of targeted next-generation sequencing to identify a candidate autosomal dominant mutation in the COL1A2 gene. A 5-month-old male Chow Chow was examined with a fractured left humerus and resolving, bilateral femoral fractures. Radiographs revealed generalized osteopenia and bilateral humeral, radial, and femoral fractures. Targeted next-generation sequencing of genes associated with OI in humans (COL1A1, COL1A2, LEPRE1, SERPINH1, and CRTAP) revealed a G>A heterozygous mutation in the splice donor site of exon 18 of the COL1A2 gene (c.936 + 1G>A). The splice donor mutation was not detected among 91 control dogs representing 21 breeds. A comparative analysis of exon 18 and the exon-intron junction further showed that the mutated splice donor site is conserved among vertebrates. Altogether, these findings reveal a candidate autosomal splice donor site mutation causing OI in an individual Chow Chow.

Multiple fractures in infants who have Ehlers-Danlos/hypermobility syndrome and or vitamin D deficiency: A case series of 72 infants whose parents were accused of child abuse and neglect

Objective: To increase the level of awareness that Ehlers-Danlos/hypermobility syndrome (EDS) and vitamin D deficiency are associated with infantile fragility fractures and radiologic features that may be mistakenly reported to be caused by non-accidental trauma due to Child Abuse and Neglect (CAN).

Patients and Methods: We constructed a case series, the largest to date, of infants with EDS who were vitamin D sufficient, insufficient and deficient and infants without EDS but with documented vitamin D deficiency and radiologic evidence of rickets who presented with multiple fractures originally diagnosed as being non-accidental and caused by child abuse. These infants were referred to the outpatient Bone Health Care Clinic at Boston University Medical Campus over a 6-year (2010–2015) period. We also present 6 index cases in which the court concluded that there was no convincing evidence of child abuse and the infants were returned to their parents. Institutional Review Board (IRB) approval was obtained.

Results: We present 72 cases of infants with multiple fractures diagnosed to be caused by non-accidental trauma. All infants were younger than one year of age. Among them, 93%(67) had clinical evidence of EDS and/or a family history with a confirmed clinical diagnosis of at least one parent having EDS and the other 7%(5) without evidence of EDS had vitamin D deficiency/infantile rickets. Three of the EDS infants were diagnosed as osteogenesis imperfecta (OI)/EDS overlap syndrome. The most common fractures noted at diagnosis were ribs and extremity fractures (including classic metaphyseal lesions). Serum levels of 25-hydroxyvitamin D [25(OH)D] were reported in 48 infants (18.0 ± 8.5 ng/ml) and in 30 mothers (21.3 ± 11.7 ng/ml). Sixty-three percent (27) of the EDS infants who had their serum 25(OH)D measured were vitamin D deficient 25(OH)D<20 ng/ml and 5 were vitamin D sufficient 25(OH)D>30 ng/ml. The mean serum level for infants with vitamin D deficiency/rickets was (10.2 ± 3.0 ng/ml)

Conclusion: EDS, OI/EDS and vitamin D deficiency/infantile rickets are associated with fragility fractures in infants that can be misinterpreted as caused by non-accidental trauma due to child abuse.

Cross-sectional and longitudinal growth patterns in osteogenesis imperfecta: implications for clinical care

BACKGROUND

There is strikingly limited information on linear growth and weight in the different types of osteogenesis imperfecta (OI). Here, we define growth patterns further with the intent of implementing appropriate adaptations proactively.

METHODS

We report cross-sectional anthropometric data for 343 subjects with different OI types (144 children, 199 adults). Longitudinal height data for 36 children (18 girls, 18 boys) with OI type I and 10 children (8 girls, 2 boys) with OI type III were obtained.

RESULTS

In all cases, the height Z-scores were negatively impacted, and final height Z-scores were impacted the most. In type I, the growth velocities taper near puberty, and there is a blunted pubertal growth spurt. The growth velocities of children with type III decelerate before age 5 y; poor growth continues without an obvious pubertal growth spurt. Obesity is a concern for all patients with OI, with type III patients being the most affected.

CONCLUSION

The linear growth patterns, in addition to the marked increase in weight over time, indicate a need for lifestyle modifications early in childhood, especially a need for weight control. Further definition of the anthropometric measures in OI enables patients to begin modifications as early as possible.

Fluoroscopy-guided Sacroiliac Joint Steroid Injection for Low Back Pain in a Patient with Osteogenesis Imperfecta

BACKGROUND

Osteogenesis imperfecta, also known as 'brittle bone disease', is a genetic connective tissue disease. It is characterized by bone fragility and osteopenia (low bone density). In this case, a 57-year old female presented to the University Hospital of the West Indies (UHWI), Physical Medicine and Rehabilitation Clinic with left low back pain rated 6/10 on the numeric rating scale (NRS). Clinically, the patient had sacroiliac joint mediated pain although X-rays did not show the sacroiliac joint changes. Fluoroscopy-guided left sacroiliac joint steroid injection was done.

METHODS

Numeric rating scale and Oswestry Disability Index (ODI) questionnaire were used to evaluate outcome. This was completed at baseline, one week follow-up and at eight weeks post fluoroscopy-guided sacroiliac joint steroid injection.

RESULTS

Numeric rating scale improved from 6/10 before the procedure to 0/10 post procedure, and ODI questionnaire score improved from a moderate disability score of 40% to a minimal disability score of 13%. Up to eight weeks, the NRS was 0/10 and ODI remained at minimal disability of 15%.

CONCLUSION

Fluoroscopy-guided sacroiliac joint injection is a known diagnostic and treatment method for sacroiliac joint mediated pain. To our knowledge, this is the first case published on the use of fluoroscopy-guided sacroiliac joint steroid injection in the treatment of sacroiliac joint mediated low back pain in a patient with osteogenesis imperfecta.

Classification of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is an extremely heterogeneous group of heritable connective tissue disorders. Most of the affected patients carry autosomal dominant mutations in the genes encoding for collagen type I, the most abundant protein of the bone extracellular matrix. The resulting phenotypes are extremely broad and have been classified by Sillence and colleagues into four groups according to clinical, radiological and genetic criteria.More recently, proteins have been described that interact directly or indirectly with collagen biosynthesis and their deficiency result in rare forms of mostly autosomal recessive OI sharing phenotypic features of 'classical' types but lacking primary defects in type I collagen. Consequently the Sillence classification has been gradually expanded to include novel forms based on the underlying mutations. The goal of this article is to revisit the actual OI classification and to outline current approaches in categorizing the disorder.

Skeletal dysplasias: A radiographic approach and review of common non-lethal skeletal dysplasias

Skeletal dysplasias are not uncommon entities and a radiologist is likely to encounter a suspected case of dysplasia in his practice. The correct and early diagnosis of dysplasia is important for management of complications and for future genetic counselling. While there is an exhaustive classification system on dysplasias, it is important to be familiar with the radiological features of common dysplasias. In this article, we enumerate a radiographic approach to skeletal dysplasias, describe the essential as well as differentiating features of common non-lethal skeletal dysplasias and conclude by presenting working algorithms to either definitively diagnose a particular dysplasia or suggest the most likely differential diagnoses to the referring clinician and thus direct further workup of the patient.

Osteogenesis imperfecta: a case report and review of literature

Osteogenesis imperfecta (OI) is a group of rare inherited disorders of connective tissue with the common feature of excessive fragility of bones caused by mutations in collagen. Diagnosis is mainly based on the clinical features of the disorder. We report, the case of a male neonate delivered to a 33-year-old para 2 female at University of Nigeria Teaching Hospital, Enugu with no family history suggestive of OI. He had clinical features of a type II OI and severe birth asphyxia. Multidisciplinary management was instituted, but he died on the 7(th) day of life.

Distal humerus atrophic nonunion in a child with osteogenesis imperfecta

Atrophic nonunion of the distal humerus in children with osteogenesis imperfecta is a vexing and disabling problem. Traditional treatments, including casting, intramedullary nailing, plating and bone grafting have not been universally successful. We report on a case of successful treatment of one atrophic nonunion of the distal humerus in ad 2 year 10 month old child with type III OI who had failed more traditional treatments. The treatment used a combination of telescoping intramedullary nails, locking plate fixation and bone morphogenic protein.

LEVEL OF EVIDENCE

Level IV.

Human recombinant type I collagen produced in plants

As a central element of the extracellular matrix, collagen is intimately involved in tissue development, remodeling, and repair and confers high tensile strength to tissues. Numerous medical applications, particularly, wound healing, cell therapy, bone reconstruction, and cosmetic technologies, rely on its supportive and healing qualities. Its synthesis and assembly require a multitude of genes and post-translational modifications, where even minor deviations can be deleterious or even fatal. Historically, collagen was always extracted from animal and human cadaver sources, but bare risk of contamination and allergenicity and was subjected to harsh purification conditions resulting in irreversible modifications impeding its biofunctionality. In parallel, the highly complex and stringent post-translational processing of collagen, prerequisite of its viability and proper functioning, sets significant limitations on recombinant expression systems. A tobacco plant expression platform has been recruited to effectively express human collagen, along with three modifying enzymes, critical to collagen maturation. The plant extracted recombinant human collagen type I forms thermally stable helical structures, fibrillates, and demonstrates bioactivity resembling that of native collagen. Deployment of the highly versatile plant-based biofactory can be leveraged toward mass, rapid, and low-cost production of a wide variety of recombinant proteins. As in the case of collagen, proper planning can bypass plant-related limitations, to yield products structurally and functionally identical to their native counterparts.

Increased nuchal translucency and short femur length as possible early signs of osteogenesis imperfecta type III

OBJECTIVE

this paper reports an association between an increased Nuchal Translucency (NT) and Osteogenesis Imperfecta (OI), a type of skeletal dysplasia. Measurement of fetal NT at 10-14 weeks of gestation is a sensitive and effective screening method for chromosomal abnormalities.

METHODS

a 35-year- old Caucasian woman in her fourth pregnancy was referred to our clinic for an ultrasound scan at 12 weeks of gestation, that confirmed increased Nuchal Translucency. Chorionic villi sampling was performed, showing a normal karyotype. The patient was evaluated by a team of experienced ultra sonographers for pregnancy follow-up at our Department, that is a tertiary center.

RESULTS

in our case the ultrasound scan at 12 week of gestation revealed only an increased NT (3 mm). Cytogenetic analysis on chorionic villi demonstrated a normal male karyotype. US follow-up, performed every 3-4 weeks, confirmed normal anthropometric parameters except for shortening of both femurs, but at 23 weeks an incorrect attitude of the feet was revealed. A clinical and radiographic diagnosis of OI type III was made only at birth, and through follow-up continuing to date.

DISCUSSION

NT screening was successful for chromosomal abnormalities at 11-14 weeks of gestation. An increased NT thickness is also associated with numerous fetal anomalies and genetic syndromes in a chromosomally normal fetus. In our case there were no sonographic signs of imperfect osteogenesis in the first trimester, although there was an increased NT with a normal karyotype.

CONCLUSION

currently, in literature, there are not other cases of OI type III associated with an increased NT. Our report is the first to suggest an association between an increased nuchal translucency, short femur length and osteogenesis imperfecta type III.

Osteogenesis Imperfecta with Celiac Disease and Type II Diabetes Mellitus Associated: Improvement with a Gluten-Free Diet

Osteogenesis imperfecta (OI) is a genetic disease, with a connective tissue alteration, consisting in the presence of multiple spontaneous fractures or after minimal traumatism. Its association with other metabolic processes is rarely described. We present the clinical case of a female adult patient of 43 years. From her infancy, she has had multiple fractures, needing several surgical interventions, and she was diagnosed of OI type 2 at adolescence age. Due mainly to difficulties in walking remaining in wheel-chair in the last three years, she was overweight with morbid obesity (BMI = 45.4) and had a type-II DM associated. She suffered from recurrent abdominal pain and chronic diarrhea and was diagnosed of celiac disease (CD) with increased intraepithelial duodenal infiltration, being classified as lymphocytic enteritis, Marsh I type. She was put on a gluten-free diet (GFD), having lost 6 kg of weight after 6 months, with a good control of DM-II and presenting a significant clinical improvement. It is rewarding to search the presence of two coincidental metabolic diseases associated to OI, specially CD, because of the dramatic clinical benefit in the general found after putting on a GFD.

A scoring system for the assessment of clinical severity in osteogenesis imperfecta

INTRODUCTION

Osteogenesis imperfecta (OI) is a genetic disorder characterized by bone fragility and fractures. Patients with OI have clinical features that may range from mild symptoms to severe bone deformities and neonatal lethality. Numerous approaches for the classification of OI have been published. The Sillence classification is the most commonly used. In this study, we aimed at developing a more refined sub-classification by applying a proposed scoring system for the quantitative assessment of clinical severity in different types of OI.

SUBJECTS AND METHODS

This study included 43 patients with OI. Clinical examination and radiological studies were conducted for all patients. Cases were classified according to the Sillence classification into types I-IV. The proposed scoring system included five major criteria of high clinical value: number of fractures per year, motor milestones, long bone deformities, length/height standard deviation score (SDS), and bone mineral density (BMD). Each criterion was assigned a score from 1 to 4, and each patient was marked on a scale from 1 to 20 according to these five criteria.

RESULTS

Applying the proposed clinical scoring system showed that all 11 patients with Sillence type I (100%) had a score between 6 and 10, denoting mild affection. The only patient with Sillence type II had a score of 19, denoting severe affection. In Sillence type III, 7 patients (31.8%) were moderately affected and 15 patients (68.2%) were severely affected. Almost all patients with Sillence type IV (88.9%) were moderately affected.

CONCLUSIONS

Applying the proposed scoring system can quantitatively reflect the degree of clinical severity in OI patients and can be used in complement with the Sillence classification and molecular studies.

Dentinogenesis imperfecta associated with osteogenesis imperfecta

This paper presents a case with dentinogenesis imperfecta (DI) associated with osteogenesis imperfecta. Systemic and dental manifestations of OI and its medical and dental treatments are discussed in this paper. A 5-year-old child with the diagnosis of OI was referred to the Dental School of Shaid Beheshti University of Medical Sciences. On clinical examination yellow/brown discoloration of primary teeth with the attrition of the exposed dentin and class III malocclusion was observed. Enamel of first permanent molars was hypoplastic. Radiographic examinations confirmed the diagnosis of DI. A histological study was performed on one of the exfoliating teeth, which showed abnormal dentin. Primary teeth with DI were more severely affected compared to permanent teeth; enamel disintegration occurred in teeth with DI, demonstrating the need for restricts recalls for these patients.

The incidence of spondylolysis and spondylolisthesis in children with osteogenesis imperfecta

BACKGROUND

Spondylolysis and spondylolisthesis are common abnormalities of the lumbar spine. The incidence of these diagnoses is recognized in the healthy population. However, their incidence in osteogenesis imperfecta (OI) patients is less well defined.

METHODS

This is a retrospective radiographic review of patients treated in the OI clinic from a single institution. Lateral radiographs were reviewed on all available patients to assess the incidence of spondylolysis and spondylolisthesis in this patient population. The morphology of the pedicle and pars interarticularis was also evaluated to identify any abnormalities or dysplasia of these structures.

RESULTS

One hundred ten of the 139 patients treated in the OI clinic met the inclusion criteria for this study. Of these patients, 79% (87 of 110) were ambulatory. The overall incidence of spondylolysis in this pediatric OI population was found to be 8.2% (9 of 110) at an average age of 7.5 years. The incidence of spondylolisthesis was 10.9% (12 of 110) at an average age of 6.5 years with 75% (3 of 12) being isthmic type and 25% (3 of 12) dysplastic. The combined incidence of spondylolysis and spondylolisthesis was 19.2%. Incidentally, the pedicle length was noted to be elongated in 40.0% (44 of 110) of this OI population.

CONCLUSIONS

This study found that the incidence of spondylolysis in a group of children with OI was much higher than in the normal pediatric population, which has been reported to be 2.6% to 4.0%. This incidence was also found to be higher than previously reported incidence of spondylolysis in OI patients (5.3%). The incidence of spondylolisthesis was also found to be much higher than that of the normal pediatric population (4.2%). It is important to recognize this higher incidence of these abnormalities and to anticipate future associated symptoms and potential worsening listhesis that can clinically affect the lifestyles of these children and potentially require surgical treatment. The clinical significance of these findings will necessitate long-term follow-up.

Effects of bisphosphonates in children with osteogenesis imperfecta: an AACPDM systematic review

This systematic review of the effects of bisphosphonate treatment in children with osteogenesis imperfecta was conducted using the American Academy for Cerebral Palsy and Developmental Medicine methodology for developing systematic reviews of treatment interventions (Revision 1.1) 2004. Despite a large body of published literature, there have been only eight studies with a sufficiently high level of internal validity to be truly informative. These studies confirm improvement in bone density. Many, but not all studies, demonstrate reduction in fracture rate and enhanced growth. There has been extremely limited evaluation of broader treatment impacts such as deformity, need for orthopedic surgery, pain, functioning, or quality of life. Short-term side effects were minimal. Which medication and dosing regimen is optimal and how long patients should be treated are unclear. This body of evidence would be strengthened by a larger controlled trial, because many studies lacked adequate power to evaluate stated outcomes. These studies do not address the impacts of bisphosphonates in children with milder forms of osteogenesis imperfecta and severe forms that are not due to mutations in the type I pro-collagen gene (e.g. types VII and VIII). Additional research is needed into treatment of infants. More studies evaluating medication choices, optimal dosing, duration of treatment, post-treatment impacts, and long-term side effects are necessary.

High frequency ultrasound prediction of mechanical properties of cortical bone with varying amount of mineral content

In this study, we evaluate if high frequency ultrasound impedance measurements can predict the mechanical properties of bones where the amount of bone mineral is varied. The motivation stems from the potential utility of ultrasound as a noninvasive technique to evaluate and monitor the mechanical properties of bone during treatment of diseased states where the ratio of mineral content to organic matrix content could change (e.g., metabolic bone diseases, osteoarthritis, osteogenesis imperfecta, fracture healing). Eleven cortical bovine femur samples, which were taken along the long axis of femur, were used in each group. Bone samples with reduced mineral content (estimated to be 21% and 35% less than the control) were obtained by immersing samples into fluoride ion solution for 3 and 12 d. Control and fluoride treated samples were first tested mechanically in tension. Acoustic impedances of the mechanically tested samples were obtained by using scanning acoustic microscopy (SAM). Results from mechanical tests indicate that the tensile elastic modulus of the samples was highly correlated to the yield strength (r(2) = 0.94, p < 0.01) and to the ultimate strength (r(2) = 0.75, p < 0.01). SAM results indicate that the acoustic impedances were significantly correlated to the elastic modulus (r(2) = 0.85, p < 0.01), yield strength (r(2) = 0.86, p < 0.01) and ultimate strength (r(2) = 0.70, p < 0.01). These results show that ultrasonic techniques could potentially be used to predict the in vivo ultimate strength of bone tissue caused by changes in mineral content.

Uniform partial dissolution of bone mineral by using fluoride and phosphate ions combination

Mineral content is one of the main predictors of the mechanical properties of bone tissue. The contribution of the bone mineral phase to the mechanical properties of bone has been investigated by reducing the mineral content of bone with different in vitro treatment techniques such as hydrochloric acid (HCl), ethylenedinitrilo tetraacetic acid (EDTA), and fluoride ion treatment. In this study, we propose a new treatment technique which combines fluoride and phosphate ions. Bovine femur specimens were used to determine the mechanical properties of cortical bone after different fluoride phosphate ion combination treatments. The treatment solutions, which contain different fluoride and phosphate ion concentrations, dissolved part of the bone mineral in a uniform manner throughout the bone samples. Dissolution by products, which precipitated in the bone tissue, contained calcium fluoride with phosphate ions (CaF(2)/P) and fluorapatite/fluorhydroxyapatite-type material (FAp/FHAp) and acted as filler. Depending on the fluoride and phosphate concentration in a treatment solution, the precipitated material's ratio of FAp/FHAp to total fluoride containing phase (FAp/FHAp + CaF(2)/P) in bone tissue also changed. High fluoride ion content in treatment solutions generated more CaF(2)/P type of precipitate, and low fluoride ion concentration generated more FAp/FHAp type precipitates as compared to high fluoride concentration treatments. These experiments show that phosphate ions are another important parameter of a treatment solution, in addition to ionic strength, pH, and the duration of treatment. In vitro, phosphate fluoride combinations partially dissolve bone mineral content in a wider range than fluoride treatment alone in a uniform manner. With this new technique one can control more precisely the partial dissolution of the bone mineral and mineral phase's contribution to mechanical properties of bone tissue.

Osteogenesis imperfecta

Osteogenesis imperfecta is a relatively common hereditary connective tissue disorder characterized by bone fragility and fractures. Other frequently affected tissues include tendons, ligaments, skin, sclera, teeth, and middle and inner ear. Molecular studies have demonstrated that most cases result from mutations affecting the genes responsible for the formation of type 1 collagen. The phenotypic presentation varies from mild to lethal. Commonly observed dental abnormalities include dentinogenesis imperfecta and malocclusion. Medical therapies using bisphosphonates have resulted in reduced fracture risk and decreased bone pain. To date, no cases of bisphosphonate-associated osteonecrosis have been reported. With appropriate precautions, the patient with osteogenesis imperfecta can tolerate and benefit from the delivery of necessary dental care to control oral disease, improve function, and improve esthetics.

Laminin-5 activates extracellular matrix production and osteogenic gene focusing in human mesenchymal stem cells

We recently reported that laminin-5, expressed by human mesenchymal stem cells (hMSC), stimulates osteogenic gene expression in these cells in the absence of any other osteogenic stimulus. Here we employ two-dimensional liquid chromatography and tandem mass spectrometry, along with the Database for Annotation, Visualization and Integrated Discovery (DAVID), to obtain a more comprehensive profile of the protein (and hence gene) expression changes occurring during laminin-5-induced osteogenesis of hMSC. Specifically, we compare the protein expression profiles of undifferentiated hMSC, hMSC cultured on laminin-5 (Ln-5 hMSC), and fully differentiated human osteoblasts (hOST) with profiles from hMSC treated with well-established osteogenic stimuli (collagen I, vitronectin, or dexamethazone). We find a marked reduction in the number of proteins (e.g., those involved with calcium signaling and cellular metabolism) expressed in Ln-5 hMSC compared to hMSC, consistent with our previous finding that hOST express far fewer proteins than do their hMSC progenitors, a pattern we call "osteogenic gene focusing." This focused set, which resembles an intermediate stage between hMSC and mature hOST, mirrors the expression profiles of hMSC exposed to established osteogenic stimuli and includes osteogenic extracellular matrix proteins (collagen, vitronectin) and their integrin receptors, calcium signaling proteins, and enzymes involved in lipid metabolism. These results provide direct evidence that laminin-5 alone stimulates global changes in gene/protein expression in hMSC that lead to commitment of these cells to the osteogenic phenotype, and that this commitment correlates with extracellular matrix production.

A narrative review of pathophysiological mechanisms associated with cervical artery dissection

OBJECTIVE

The purpose of this narrative review was to describe pathophysiological risk factors that have been reported in association with cervical artery dissection (CAD) and to discuss the strength of those associations.

DATA SOURCES

MEDLINE, PubMed, Manual Alternative and Natural Therapy System (MANTIS), and CINAHL databases were searched for the years 1966 through September 2006. Additionally, the literature generated by the searches was culled for relevant citations incorporated within the articles.

RESULTS

The search strategy generated a total of 130 distinct citations, of which 49 were determined to be relevant after applying the study's selection criteria. An additional 6 references were harvested from the reference lists of the included articles.

SUMMARY

The most compelling pathophysiological risk factors have to do with connective tissue abnormalities, which may contribute to a weakening of the vascular wall making it more susceptible to tearing. However, the exact pathogenesis of CAD is uncertain, especially in cases that occur spontaneously, are related to trivial trauma, or occur in the absence of discernable risk factors.

Functional significance of bone density measurements in children with osteogenesis imperfecta

BACKGROUND

The treatment of osteogenesis imperfecta has been directed at improvement of bone mineral density, yet the importance of bone mineral density in predicting functional and clinical outcome in this patient population has not been demonstrated. We used a validated functional outcome measure to identify the relationship between bone mineral density and physical function in children with osteogenesis imperfecta, and we also evaluated the relationship of bone mineral density to the rate of surgery and fracture in patients with osteogenesis imperfecta.

METHODS

Twenty patients (age range, four to seventeen years) with osteogenesis imperfecta who had undergone bone mineral densitometry as measured by dual x-ray absorptiometry of the lumbar spine, wrist, and proximal aspect of the femur between November 1999 and April 2001 were retrospectively analyzed. Functional outcome was measured with use of the Pediatric Outcomes Data Collection Instrument. These questionnaires were completed by the parents of all twenty patients and, in addition, by fifteen patients in the study who were between the ages of eleven and eighteen years. Fracture and surgery rates were calculated on the basis of the number of documented fractures and surgical procedures that the patient had had from the time of the initial presentation until the time of the latest follow-up visit.

RESULTS

There were significant relationships between the bone mineral density of the lumbar spine and the scores obtained on the parent-completed questionnaires with regard to upper-extremity functioning (r = 0.57, p < 0.01), transfers and basic mobility (r = 0.55, p = 0.01), sports and physical functioning (r = 0.55, p = 0.01), and global functioning (r = 0.60, p < 0.004). There were also significant relationships between the bone mineral density of the wrist and the scores obtained on the child-completed questionnaires with regard to upper-extremity functioning (r = 0.82, p < 0.01), sports and physical functioning (r = 0.76, p < 0.01), and global functioning (r = 0.83, p = 0.001). There were significant negative relationships between the bone mineral density of the lumbar spine and the rate of fractures (r = -0.69, p < 0.001) and the bone mineral density of the lumbar spine and the rate of surgery (r = -0.60, p < 0.01).

CONCLUSIONS

There is a relationship between bone mineral density and the functional outcome, rate of fracture, and rate of surgery in patients with osteogenesis imperfecta. Bone mineral density appears to be an indicator of disease severity and may be predictive of long-term functional outcome. To establish specific guidelines for treatment, more data on normative bone-mineral density in children with osteogenesis imperfecta will be needed.

Growth hormone injections improve bone quality in a mouse model of osteogenesis imperfecta

Systemic growth hormone injections increased spine and femur length in a mouse model of OI. Femur BMC, cross-sectional area, and BMD were increased. Smaller gains were produced in vertebral BMC and cross-sectional area. Biomechanical testing showed improvements to structural and material properties in the femur midshaft, supporting expanded testing of growth hormone therapy in children with OI.

INTRODUCTION

Osteoblasts in heterozygous Cola2oim mutant mice produce one-half the normal amounts of the alpha2 strand of type I procollagen. The mice experience a mild osteogenesis imperfecta (OI) phenotype, with femurs and vertebrae that require less force than normal to break in a biomechanical test.

MATERIALS AND METHODS

Subcutaneous injections of recombinant human growth hormone (rhGH) or saline were given 6 days per week to oim/+ mice between 3 and 12 weeks of age, in a protocol designed to simulate a trial on OI children.

RESULTS

rhGH injections promoted significant weight gain and skeletal growth compared with saline-treated control animals. Femur and spine lengths were increased significantly. Significant increases at the femur midshaft in cortical BMD (2.2%), BMC (15.5%), and cross-sectional area (13%) were produced by rhGH treatment. Increases in the same cortical bone parameters were measured in the metaphyseal region of the femur and in tail vertebrae, but lumbar vertebrae showed significant increases in BMC (9.6%) and cross-sectional area (10.1%) of trabecular bone. Three-point bending testing documented functional improvements to the femur mid-shafts. GH treatment produced significant increases in bone stiffness (23.7%), maximum load (30.8%), the energy absorbed by the femurs to the point of maximum load (44.5%), and the energy to actual fracture (40.4%). The ultimate stress endured by the bone material was increased by 14.1%.

CONCLUSIONS

Gains in bone length, cross-sectional area, BMD, BMC, structural biomechanical properties, and strength were achieved without directly addressing the genetic collagen defect in the mice. Results support expanded clinical testing of GH injections in children with OI.