Parkinson's disease: A risk factor for osteoporosis

The Brain-Gut-Bone Axis in Neurodegenerative Diseases: Insights, Challenges, and Future Prospects

Neurodegenerative diseases are global health challenges characterized by the progressive degeneration of nerve cells, leading to cognitive and motor impairments. The brain-gut-bone axis, a complex network that modulates multiple physiological systems, has gained increasing attention owing to its profound effects on the occurrence and development of neurodegenerative diseases. No comprehensive review has been conducted to clarify the triangular relationship involving the brain-gut-bone axis and its potential for innovative therapies for neurodegenerative disorders. In light of this, a new perspective is aimed to propose on the interplay between the brain, gut, and bone systems, highlighting the potential of their dynamic communication in neurodegenerative diseases, as they modulate multiple physiological systems, including the nervous, immune, endocrine, and metabolic systems. Therapeutic strategies for maintaining the balance of the axis, including brain health regulation, intestinal microbiota regulation, and improving skeletal health, are also explored. The intricate physiological interactions within the brain-gut-bone axis pose a challenge in the development of effective treatments that can comprehensively target this system. Furthermore, the safety of these treatments requires further evaluation. This review offers a novel insights and strategies for the prevention and treatment of neurodegenerative diseases, which have important implications for clinical practice and patient well-being.

Network pharmacology and untargeted metabolomic-based investigation of anti-osteoporotic effects of viscozyme-assisted polysaccharide from Portulaca oleracea L

Osteoporosis is a metabolic bone disease closely associated with oxidative stress. We had previously confirmed that the Viscozyme-assisted polysaccharide from Portulaca oleracea L (VPOP1) protects against antioxidant stress and evaluated the structure of VPOP1. In this study, we aimed to explore the anti-osteoporotic effects of VPOP1 on H2O2-induced osteoblast apoptosis. In addition, untargeted zebrafish metabolomics based on UPLC-Q-Orbitrap-HRMS was used to investigate the potential anti-osteoporotic mechanisms of VPOP1. The levels of Bcl-2 decreased significantly and those of caspase-3, Bax, and cytochrome C increased after treatment with H2O2. VPOP1 inhibited apoptosis in H2O2-induced MC3T3 cells. Metabolomic analyses showed that 28 potential biomarkers were gradually restored to normal levels after treatment with VPOP1 compared with that in the model group. Among them, leukotrienes D4 and A4, L-dopa, and L-tyrosine are important biomarkers and therapeutic targets. Pathway analysis revealed that arachidonic acid, tyrosine, phenylalanine, and sphingolipid metabolism were the major intervening pathways. Collectively, these results help us understand the protective activity of large molecular weight compounds, such as VPOP1, against osteoporosis.

Osteoporosis in Parkinson's disease and the role of lean body mass: a cross-sectional study in a Brazilian tertiary center

Background

Parkinson's disease (PD) is the second most common neurodegenerative illness and has the highest increase rate in recent years. There is growing evidence to suggest that PD is linked to higher osteoporosis rates and risk of fractures.

Objective

This study aims to estimate the prevalence and factors associated with osteoporosis as defined by the National Osteoporosis Foundation (NOF) and World Health Organization in patients with mild to moderate PD.

Methods

We performed a cross-sectional study at a tertiary public hospital in Fortaleza, Brazil, dating from May 2021 until April 2022. The study sample was comprised of patients with mild to moderate PD who were at least 40 years old and who had the ability to walk and stand unassisted. Bone Mineral Density (BMD) of both the hip (neck of the femur) and the lumbar spine were obtained via properly calibrated Dual Energy X-ray Absorptiometry (DXA) scanning. The FRAX (Fracture Risk Assessment Tool) score was used to determine a person's 10-year risk of major osteoporotic fracture. The Revised European Working Group on Sarcopenia in Older People (EWGSOP 2) was used as a basis to confirm a sarcopenia diagnosis with the following parameters: low muscle strength gauged by handgrip strength and low muscle quantity by DXA. Physical performance was carefully evaluated by using the Short Physical Performance Battery test. Osteoporosis and osteopenia were diagnosed following the NOF guidelines and WHO recommendations.

Results

We evaluated 107 patients in total, of whom 45 (42%) were women. The group's mean age was 68 ± 9 years, and the mean disease time span was 9.9 ± 6.0 years and mean motor UPDRS was 43 ± 15. We found that 42.1% and 34.6% of the sample had osteopenia and osteoporosis following NOF criteria, respectively, and 43% and 33.6% following the WHO recommendations. Lower lean appendicular mass was associated to osteopenia and osteoporosis in multinomial logistic regression analysis in both diagnostic criteria.

Conclusion

Our findings provide additional evidence for the protective role of lean mass against osteoporosis in patients with PD.

Bone involvement in the early stages of Parkinson's disease: a case-control study

OBJECTIVE

To evaluate the qualitative and quantitative alterations of bone tissue in patients with early-stage Parkinson's disease (PD) and to measure the associations between bone mineral density (BMD), trabecular bone score (TBS) and physical performance.

METHODS

This case-control study enrolled patients with early-stage PD and age-matched controls. BMDs for the left femoral neck (L-FN) and lumbar spine (LS) were measured. Bone microarchitecture for the LS was determined using TBS. Muscle performance was assessed using the short physical performance battery (SPPB). Patients and controls were stratified in two groups based on the SPPB score: a poor performance group (SPPB score ≤8) and high performance group (SPPB > 8).

RESULTS

This study included 26 patients: 13 in the PD group and 13 age-matched controls. The mean ± SD BMD results in the PD group were: L1-L4 BMD = 0.935 ± 0.183 g/cm2; L-FN BMD = 0.825 ± 0.037 g/cm2; with bone microarchitecture degraded in four patients and partially degraded in three patients. TBS was significantly different in the patients with PD stratified according to SPPB. Among the controls, there was a significant difference in body mass index between the two SPPB groups.

CONCLUSION

TBS might identify bone involvement earlier than BMD in the initial stages of PD.

Unravelling the mechanisms of underweight in Parkinson's disease by investigating into the role of gut microbiome

Approximately half of patients with Parkinson's disease (PD) suffer from unintentional weight loss and are underweight, complicating the clinical course of PD patients. Gut microbiota alteration has been proven to be associated with PD, and recent studies have shown that gut microbiota could lead to muscle wasting, implying a possible role of gut microbiota in underweight PD. In this study, we aimed to (1) investigate the mechanism underlying underweight in PD patients with respect to gut microbiota and (2) estimate the extent to which gut microbiota may mediate PD-related underweight through mediation analysis. The data were adapted from Hill-Burns et al., in which 330 participants (199 PD, 131 controls) were enrolled in the study. Fecal samples were collected from participants for microbiome analysis. 16S rRNA gene sequence data were processed using DADA2. Mediation analysis was performed to quantify the effect of intestinal microbial alteration on the causal effect of PD on underweight and to identify the key bacteria that significantly mediated PD-related underweight. The results showed that the PD group had significantly more underweight patients (body mass index (BMI) < 18.5) after controlling for age and sex. Ten genera and four species were significantly different in relative abundance between the underweight and non-underweight individuals in the PD group. Mediation analysis showed that 42.29% and 37.91% of the effect of PD on underweight was mediated through intestinal microbial alterations at the genus and species levels, respectively. Five genera (Agathobacter, Eisenbergiella, Fusicatenibacter, Roseburia, Ruminococcaceae_UCG_013) showed significant mediation effects. In conclusion, we found that up to 42.29% of underweight PD cases are mediated by gut microbiota, with increased pro-inflammatory bacteria and decreased SCFA-producing bacteria, which indicates that the pro-inflammatory state, disturbance of metabolism, and interference of appetite regulation may be involved in the mechanism of underweight PD.

Myeloid Cells As a Promising Target for Brain-Bone Degenerative Diseases from a Metabolic Point of View

Brain and bone degenerative diseases such as Alzheimer's disease and osteoporosis are common in the aging population and lack efficient pharmacotherapies. Myeloid cells are a diverse group of mononuclear cells that plays important roles in development, immune defense, and tissue homeostasis. Aging drastically alters the expansion and function of myeloid cells, which might be a common pathogenesis of the brain-bone degenerative diseases. From this perspective, the role of myeloid cells in brain-bone degenerative diseases is discussed, with a particular focus on metabolic alterations in myeloid cells. Furthermore, targeting myeloid cells through metabolic regulation via drugs such as metformin and melatonin is proposed as a potential therapy for the clinical treatment of brain-bone diseases.

Adult Spinal Deformity Correction in Patients with Parkinson Disease: Assessment of Surgical Complications, Reoperation, and Cost

BACKGROUND

Parkinson disease (PD) is a neurodegenerative disorder that manifests with postural instability and gait imbalance. Correction of spinal deformity in patients with PD presents unique challenges.

METHODS

The PearlDiver database was queried between 2010 and 2020 to identify adult patients with spinal deformity before undergoing deformity correction with posterior spinal fusion. Two cohorts were created representing patients with and without a preoperative diagnosis of PD. Outcome measures included reoperation rates, surgical technique, cost, surgical complications, and medical complications. Multivariable logistic regression adjusting for Charlson Comorbidity Index, age, gender, 3-column osteotomy, pelvic fixation, and number of levels fused was used to assess rates of reoperation and complications.

RESULTS

In total, 26,984 patients met the inclusion criteria and were retained for analysis. Of these patients, 725 had a diagnosis of PD before deformity correction. Patients with PD underwent higher rates of pelvic fixation (odds ratio [OR], 1.33; P < 0.001) and 3-column osteotomies (OR, 1.53; P < 0.001). On adjusted regression, patients with PD showed increased rates of reoperation at 1 year (OR, 1.37; P < 0.001), 5 years (OR, 1.32; P < 0.001), and overall (OR, 1.33; P < 0.001). Patients with PD also experienced an increased rate of medical complications within 30 days after deformity correction including deep venous thrombosis (OR, 1.60; P = 0.021), pneumonia (OR, 1.44; P = 0.039), and urinary tract infections (OR, 1.54; P < 0.001). Deformity correction in patients with PD was associated with higher 90-day cost (P = 0.007).

CONCLUSIONS

Patients with PD undergoing long fusion for deformity correction are at significantly increased risk of 30-day medical complications and revision procedures after 1 year, controlling for comorbidities, age, and invasiveness. Surgeons should consider the risk of complications, subsequent revision procedures, and increased cost.

Bone Tissue and the Nervous System: What Do They Have in Common?

Degenerative diseases affecting bone tissues and the brain represent important problems with high socio-economic impact. Certain bone diseases, such as osteoporosis, are considered risk factors for the progression of neurological disorders. Often, patients with neurodegenerative diseases have bone fractures or reduced mobility linked to osteoarthritis. The bone is a dynamic tissue involved not only in movement but also in the maintenance of mineral metabolism. Bone is also associated with the generation of both hematopoietic stem cells (HSCs), and thus the generation of the immune system, and mesenchymal stem cells (MSCs). Bone marrow is a lymphoid organ and contains MSCs and HSCs, both of which are involved in brain health via the production of cytokines with endocrine functions. Hence, it seems clear that bone is involved in the regulation of the neuronal system and vice versa. This review summarizes the recent knowledge on the interactions between the nervous system and bone and highlights the importance of the interaction between nerve and bone cells. In addition, experimental models that study the interaction between nerve and skeletal cells are discussed, and innovative models are suggested to better evaluate the molecular interactions between these two cell types.

Parkin Inhibits RANKL-Induced Osteoclastogenesis and Ovariectomy-Induced Bone Loss

Osteoporosis and osteoporotic fractures comprise a substantial health and socioeconomic burden. The leading cause of osteoporosis is an imbalance in bone formation and bone resorption caused by hyperactive osteoclasts. Therefore, a new strategy to suppress osteoclastogenesis is needed. Parkin is likely closely associated with bone metabolism, although its role in osteoclastogenesis is unclear. In this study, the Parkin protein inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation, osteoclast-specific gene expression, F-actin ring formation, and bone resorption pit formation in vitro. Moreover, depletion of Parkin enhanced RANKL-induced osteoclast formation, osteoclast-specific gene expression, F-actin ring formation, and bone resorption pit formation. Reactive oxygen species (ROS) activity was suppressed, while autophagy was upregulated with the presence of the Parkin protein. ROS activity was upregulated and autophagy was decreased due to Parkin knockdown. In addition, intravenous administration of Parkin rescued ovariectomy-induced bone loss and reduced osteoclastogenesis in vivo. Collectively, Parkin has therapeutic potential for diseases associated with overactive osteoclasts.

Untargeted Metabolomics Reveal the Protective Effect of Bone Marrow Mesenchymal Stem Cell Transplantation Against Ovariectomy-Induced Osteoporosis in Mice

Bone marrow mesenchymal stem cell transplantation (BMSCT) is a potential treatment for osteoporosis, capable of contributing to bone tissue repair. BMSCT has demonstrated osteoinductive effects and the ability to regulate microenvironmental metabolism; however, its role and mechanisms in bone loss due to reduced estrogen levels remain unclear. In this study, the effect of BMSCT on ovariectomy (OVX)-induced osteoporosis in mice was assessed, and liquid chromatography–mass spectrometry (LC-MS) metabolomic studies of bone tissue were conducted to identify potential metabolic molecular markers. The results revealed that BMSCT reduces OVX-induced bone loss in mice while improving the mechanical properties of mouse femurs and increasing the expression of osteogenic markers in peripheral blood. In a metabolomic study, 18 metabolites were screened as potential biomarkers of the anti-osteoporotic effect of BMSCT. These metabolites are mainly involved in arachidonic acid metabolism, taurine and hypotaurine metabolism, and pentose and glucuronate interconversions. Collectively, these results illustrate the correlation between metabolites and the underlying mechanisms of osteoporosis development and are important for understanding the role and mechanisms of exogenous bone marrow mesenchymal stem cells (BMSCs) in osteoporosis management. This study lays the foundation for research on BMSCs as a treatment strategy for osteoporosis.

Prevalence and associated factors of malnutrition in patients with Parkinson's disease using CONUT and GNRI

OBJECTIVE

Parkinson's disease (PD) is a common neurodegenerative disease, but its nutritional problems have not received enough attention. This study aims to identify the prevalence and associated factors of malnutrition in PD patients using two simple nutritional tools.

METHODS

We conducted a large-scale cross-sectional study with 1478 PD patients and equal healthy controls (HC). The controlling nutritional status score (CONUT) and geriatric nutritional risk index (GNRI) were used for malnutrition stratification.

RESULTS

By CONUT or GNRI, the prevalence of malnutrition in PD patients was higher than that in HC (40.7% vs. 25.3% and 11.1% vs. 2.1%, respectively). The binary logistic regression model showed that malnutrition in PD was associated with male sex (OR = 0.600, P < 0.001), older age (OR = 1.015, P = 0.003), lower body mass index (BMI) (OR = 0.942, P < 0.001), higher levodopa equivalent daily doses (LEDD) (OR = 1.001, P < 0.001), worse motor symptoms (OR = 1.012, P = 0.004), more serious perceptual problems/hallucinations (OR = 1.067, P = 0.019) by CONUT. In comparison, older age (OR = 1.045, P < 0.001), lower blood lymphocyte count (OR = 0.607, P = 0.006), lower serum total cholesterol levels (OR = 0.991, P < 0.001), dyskinesia (OR = 2.231, P = 0.002), worse motor symptoms (OR = 1.016, P = 0.015), more severe depression (OR = 1.028, P = 0.008) and perceptual problems/hallucinations (OR = 1.061, P = 0.033) were associated with malnutrition in PD by GNRI.

CONCLUSIONS

Our study indicated that malnutrition is more prevalent in PD patients than HC. Multidimensional risk factors for malnutrition in PD should be taken seriously.

Clinical and imaging features of surgically treated low lumbar osteoporotic vertebral collapse in patients with Parkinson's disease

Osteoporosis and Parkinson's disease (PD) are age-related diseases, and surgery for osteoporotic vertebral collapse (OVC) in PD patients become more common. OVC commonly affects the thoracolumbar spine, but low lumbar OVC is frequent in patients with lower bone mineral density (BMD). The aim of this study was to identify differences in clinical and imaging features of low lumbar OVC with or without PD and to discuss the appropriate treatment. The subjects were 43 patients with low lumbar OVC below L3 who were treated surgically, including 11 patients with PD. The main clinical symptoms were radicular pain in non-PD cases and a cauda equina sign in PD cases. Rapid progression and destructive changes of OVC were seen in patients with PD. The morphological features of OVC were flat-type in non-PD cases with old compression fracture, and destruction-type in PD cases without old compression fracture. Progression of PD was associated with decreased lumbar lordosis, lower lumbar BMD, and severe sarcopenia. High postoperative complication rates were associated with vertebral fragility and longer fusion surgery. Progression of postural instability as a natural course of PD may lead to mechanical stress and instrumentation failure. Invasive long-fusion surgery should be avoided for single low lumbar OVC.

Amino acid metabolism and autophagy in skeletal development and homeostasis

Bone is an active organ that is continuously remodeled throughout life via formation and resorption; therefore, a fine-tuned bone (re)modeling is crucial for bone homeostasis and is closely connected with energy metabolism. Amino acids are essential for various cellular functions as well as an energy source, and their synthesis and catabolism (e.g., metabolism of carbohydrates and fatty acids) are regulated through numerous enzymatic cascades. In addition, the intracellular levels of amino acids are maintained by autophagy, a cellular recycling system for proteins and organelles; under nutrient deprivation conditions, autophagy is strongly induced to compensate for cellular demands and to restore the amino acid pool. Metabolites derived from amino acids are known to be precursors of bioactive molecules such as second messengers and neurotransmitters, which control various cellular processes, including cell proliferation, differentiation, and homeostasis. Thus, amino acid metabolism and autophagy are tightly and reciprocally regulated in our bodies. This review discusses the current knowledge and potential links between bone diseases and deficiencies in amino acid metabolism and autophagy.

The effect of denosumab on pedicle screw fixation: a prospective 2-year longitudinal study using finite element analysis

BACKGROUND

Pedicle screw loosening is a major complication following spinal fixation associated with osteoporosis in elderly. However, denosumab is a promising treatment in patients with osteoporosis. The effect of denosumab on pedicle screw fixation is unknown. Therefore, we investigated whether denosumab treatment improves pedicle screw fixation in elderly patients with osteoporosis.

METHODS

This was a 2-year prospective open-label study. From February 2015 to January 2016, we included 21 patients with postmenopausal osteoporosis who received initial denosumab treatment. At baseline, 12 months, and 24 months, we measured volumetric bone mineral density (BMD) using quantitative computed tomography (QCT) and performed CT-based finite element analysis (FEA). Finite element models of L4 vertebrae were created to analyze the bone strength and screw fixation.

RESULTS

BMD increased with denosumab treatment. FEA revealed that both pullout strength of pedicle screws and compression force of the vertebra increased significantly at 12 and 24 months following denosumab treatment. Notably, pullout strength showed a stronger correlation with three-dimensional volumetric BMD around pedicle screw placement assessed by QCT (r = 0.83, at 24 months) than with two-dimensional areal BMD assessed by dual energy X-ray absorptiometry (r = 0.35, at 24 months).

CONCLUSION

To our knowledge, this is the first study to reveal that denosumab treatment achieved strong pedicle screw fixation with an increase in BMD around the screw assessed by QCT and FEA; therefore, denosumab could be useful for osteoporosis treatment during spinal surgery in elderly patients with osteoporosis.

Effects of Neurological Disorders on Bone Health

Neurological diseases, particularly in the context of aging, have serious impacts on quality of life and can negatively affect bone health. The brain-bone axis is critically important for skeletal metabolism, sensory innervation, and endocrine cross-talk between these organs. This review discusses current evidence for the cellular and molecular mechanisms by which various neurological disease categories, including autoimmune, developmental, dementia-related, movement, neuromuscular, stroke, trauma, and psychological, impart changes in bone homeostasis and mass, as well as fracture risk. Likewise, how bone may affect neurological function is discussed. Gaining a better understanding of brain-bone interactions, particularly in patients with underlying neurological disorders, may lead to development of novel therapies and discovery of shared risk factors, as well as highlight the need for broad, whole-health clinical approaches toward treatment.

Factors That Predict 1-Year Incident Hip and Non-Hip Fractures for Home Care Recipients: A Linked-Data Retrospective Cohort Study

OBJECTIVES

The purpose of our study was to identify factors that predict 1-year incident hip and major osteoporotic non-hip fractures (ie, wrist, spine, pelvis, humerus) for home care recipients while accounting for the competing risk of death.

DESIGN

We conducted a retrospective cohort study with linked population data.

SETTING AND PARTICIPANTS

All home care recipients in Ontario, Canada, receiving services for more than 6 months with an admission assessment between April 1, 2011, and March 31, 2015, were included.

METHODS

Clinical data from the Resident Assessment Instrument Home Care were linked to fracture data from the Discharge Abstract Database and the National Acute Care Reporting System. Competing risk proportional hazard regressions using the Fine and Grey method were performed to model the association between potential risk factors and fracture.

RESULTS

Previous fall, previous fracture, cognitive impairment, unsteady gait, alcohol use, tobacco use, and Parkinson disease were consistently associated with all fracture types. Cognitive impairment (hazard ratio 2.09; 95% confidence interval 1.86-2.36) and wandering [1.66 (1.06-1.27)] were most predictive of hip fractures and being female [1.86 (1.76-1.98)] and experiencing a previous fracture [1.86 (1.76-1.98)] were most predictive of non-hip fractures. Risk factors unique to non-hip fractures as compared with hip fractures were locomotion ability outdoors and psychotropic medication use.

CONCLUSIONS AND IMPLICATIONS

Our results indicate that, in addition to typical fracture risk factors, home care recipients have unique characteristics that increase their risk. Fracture risk assessment tools and subsequent prevention strategies should be modified to accurately identify home care recipients at risk for imminent 1-year fracture.

Acute Spinal Cord Contusion in a Patient with Multiple Upper Cervical Fractures, Parkinson's Disease, and Torticollis: Surgical Management

Case Report. Spine surgery in patients with Parkinson's disease (PD) involves increased risk. We describe a case of cervical myelopathy in a patient with PD, multiple fractures involving the atlas and axis vertebrae, and spasmodic torticollis. The patient was successfully treated with an upper cervical decompression and occipital-cervical (OC) fusion surgery. Strategies for torticollis reduction and successful surgical outcome are discussed. Risks and benefits must be carefully weighed when considering occipital cervical fusion in PD patients. Conclusion. Intraoperative manual reduction of laterocollis is possible after general endotracheal anesthesia, and continuous neuromonitoring is established. Use of optimizing strategies such as perioperative botulinum injections and intraoperative O-arm navigation should be considered.

Upregulation of Parkin Accelerates Osteoblastic Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells and Bone Regeneration by Enhancing Autophagy and β-Catenin Signaling

Osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) plays a key role in bone formation. Parkin, an E3 ubiquitin ligase, related to Parkinson’s disease and aging. Previous studies have indicated that Parkinson’s disease have a higher risk of osteoporotic fracture. To investigate the effects and underlying mechanism of Parkin in the osteogenic differentiation of BMSCs, osteogenic differentiation was analyzed following upregulation or downregulation of Parkin. We found that Parkin was increased during differentiation. Parkin overexpression enhanced osteo-specific markers, and downregulation of Parkin mitigated osteo-specific markers. Moreover, upregulation of Parkin promoted β-catenin expression and autophagy and vice versa. The upregulation of β-catenin enhanced autophagy, and the activation of autophagy also increased the expression of β-catenin in Parkin-downregulated BMSCs. Parkin-overexpressed cell sheets accelerated bone healing in a tibial fracture model. Based on these results, we concluded that Parkin meditates osteoblastic differentiation of BMSCs via β-catenin and autophagy signaling.

The relationships of vitamin D, vitamin D receptor gene polymorphisms, and vitamin D supplementation with Parkinson's disease

In recent years, many studies have investigated the correlations between Parkinson's disease (PD) and vitamin D status, but the conclusion remains elusive. The present review focuses on the associations between PD and serum vitamin D levels by reviewing studies on the associations of PD with serum vitamin D levels and vitamin D receptor (VDR) gene polymorphisms from PubMed, Web of Science, Cochrane Library, and Embase databases. We found that PD patients have lower vitamin D levels than healthy controls and that the vitamin D concentrations are negatively correlated with PD risk and severity. Furthermore, higher vitamin D concentrations are linked to better cognitive function and mood in PD patients. Findings on the relationship between VDR gene polymorphisms and the risk of PD are inconsistent, but the FokI (C/T) polymorphism is significantly linked with PD. The occurrence of FokI (C/T) gene polymorphism may influence the risk, severity, and cognitive ability of PD patients, while also possibly influencing the effect of Vitamin D3 supplementation in PD patients. In view of the neuroprotective effects of vitamin D and the close association between vitamin D and dopaminergic neurotransmission, interventional prospective studies on vitamin D supplementation in PD patients should be conducted in the future.

A genome-wide scan for pleiotropy between bone mineral density and nonbone phenotypes

Osteoporosis is the most common metabolic bone disorder globally and is characterized by skeletal fragility and microarchitectural deterioration. Genetic pleiotropy occurs when a single genetic element is associated with more than one phenotype. We aimed to identify pleiotropic loci associated with bone mineral density (BMD) and nonbone phenotypes in genome-wide association studies. In the discovery stage, the NHGRI-EBI Catalog was searched for genome-wide significant associations (P value < 5 × 10-8), excluding bone-related phenotypes. SNiPA was used to identify proxies of the significantly associated single nucleotide polymorphisms (SNPs) (r 2 = 1). We then assessed putative genetic associations of this set of SNPs with femoral neck (FN) and lumbar spine (LS) BMD data from the GEFOS Consortium. Pleiotropic variants were claimed at a false discovery rate < 1.4 × 10-3 for FN-BMD and < 1.5 × 10-3 for LS-BMD. Replication of these genetic markers was performed among more than 400 000 UK Biobank participants of European ancestry with available genetic and heel bone ultrasound data. In the discovery stage, 72 BMD-related pleiotropic SNPs were identified, and 12 SNPs located in 11 loci on 8 chromosomes were replicated in the UK Biobank. These SNPs were associated, in addition to BMD, with 14 different phenotypes. Most pleiotropic associations were exhibited by rs479844 (AP5B1, OVOL1 genes), which was associated with dermatological and allergic diseases, and rs4072037 (MUC1 gene), which was associated with magnesium levels and gastroenterological cancer. In conclusion, 12 BMD-related genome-wide significant SNPs showed pleiotropy with nonbone phenotypes. Pleiotropic associations can deepen the genetic understanding of bone-related diseases by identifying shared biological mechanisms with other diseases or traits.

Sagittal imbalance, muscle atrophy, and osteoporosis: risk factors for revision posterior lumbar fusion surgery in patients with Parkinson's disease

OBJECTIVE

The aim of our study was to evaluate features and complications of patients with Parkinson's disease (PD) who underwent posterior lumbar fusion surgery for lumbar degenerative diseases (LDD), as well as the risk factors for revision.

METHODS

Between January 2010 and December 2016, 132 patients were retrospectively identified for inclusion. Patients were divided into a 29 revision PD group and a 103 non-revision PD group. Patient factors included bone mineral density (BMD) and severity of PD using the Hoehn and Yahr staging system. Surgical factors included surgical levels and fusion methods. Radiographic measurements included pre-operative spinopelvic parameters, paraspinal muscle atrophy, and fatty infiltration. Logistic regression analysis was used to determine independent predictors for revision posterior lumbar fusion.

RESULTS

The average age of the PD patients was 67.96 years, and the follow-up time was 49.01 months. R-PD patients accounted for 21.97% of all PD patients who underwent lumbar fusion surgery. Multivariable analysis indicated that low BMD (p = 0.012), fatty infiltration (p = 0.038), a smaller relative cross-sectional area (rCSA) of the paraspinal muscle (p = 0.008), larger pelvic incidence-lumbar lordosis (PI-LL) (p = 0.01), and sagittal vertical axis (SVA) (p = 0.004) were significant independent risk factors for revision posterior lumbar fusion in PD patients.

CONCLUSION

PD patients with low pre-operative BMD, fatty infiltration, a smaller rCSA of the paraspinal muscle, and larger PI-LL and SVA had a higher rate of revision lumbar fusion. Maintaining sagittal balance, functional exercises, and anti-osteoporosis treatment were important in preventing complications in PD patients.

Ubiquitylomes Analysis of the Whole blood in Postmenopausal Osteoporosis Patients and healthy Postmenopausal Women

Objectives

To determine the mechanisms of ubiquitination in postmenopausal osteoporosis and investigate the ubiquitinated spectrum of novel targets between healthy postmenopausal women and postmenopausal osteoporosis patients, we performed ubiquitylome analysis of the whole blood of postmenopausal women and postmenopausal osteoporosis patients.

Methods

To obtain a more comprehensive understanding of the postmenopausal osteoporosis mechanism, we performed a quantitative assessment of the ubiquitylome in whole blood from seven healthy postmenopausal women and seven postmenopausal osteoporosis patients using high‐performance liquid chromatography fractionation, affinity enrichment, and liquid chromatography coupled to tandem mass spectrometry (LC‐MS/MS). To examine the ubiquitylome data, we performed enrichment analysis using an ubiquitylated amino acid motif, Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway.

Results

Altogether, 133 ubiquitinated sites and 102 proteins were quantified. A difference of more than 1.2 times is considered significant upregulation and less than 0.83 significant downregulation; 32 ubiquitinated sites on 25 proteins were upregulated and 101 ubiquitinated sites on 77 proteins were downregulated. These quantified proteins, both with differently ubiquitinated sites, participated in various cellular processes, such as cellular processes, biological regulation processes, response to stimulus processes, single‐organism and metabolic processes. Ubiquitin conjugating enzyme activity and ubiquitin‐like protein conjugating enzyme activity were the most highly enriched in molecular function of upregulated sites with corresponding proteins, but they were not enriched in downregulated in sites with corresponding proteins. The KEGG pathways analysis of quantified proteins with differentiated ubiquitinated sites found 13 kinds of molecular interactions and functional pathways, such as glyoxylate and decarboxylate metabolism, dopaminergic synapse, ubiquitin‐mediated proteolysis, salivary secretion, coagulation and complement cascades, Parkinson's disease, and hippo signaling pathway. In addition, hsa04120 ubiquitin‐mediated proteolysis was the most highly enriched in proteins with upregulated sites, hsa04610 complement and coagulation cascades was the most highly enriched in proteins with downregulated ubiquitinated sites, and hsa04114 Oocyte meiosis was the most highly enriched among all differential proteins.

Conclusion

Our study expands the understanding of the spectrum of novel targets that are differentially ubiquitinated in whole blood from healthy postmenopausal women and postmenopausal osteoporosis patients. The findings will contribute toward our understanding of the underlying proteostasis pathways in postmenopausal osteoporosis and the potential identification of diagnostic biomarkers in whole blood.

Bone loss caused by dopaminergic degeneration and levodopa treatment in Parkinson's disease model mice

Accumulating evidence have shown the association of Parkinson’s disease (PD) with osteoporosis. Bone loss in PD patients, considered to be multifactorial and a result of motor disfunction, is a hallmark symptom that causes immobility and decreased muscle strength, as well as malnutrition and medication. However, no known experimental evidence has been presented showing deleterious effects of anti-PD drugs on bone or involvement of dopaminergic degeneration in bone metabolism. Here, we show that osteoporosis associated with PD is caused by dopaminergic degeneration itself, with no deficit of motor activity, as well as treatment with levodopa, the current gold-standard medication for affected patients. Our findings show that neurotoxin-induced dopaminergic degeneration resulted in bone loss due to accelerated osteoclastogenesis and suppressed bone formation, which was associated with elevated prolactin. On the other hand, using an experimental model of postmenopausal osteoporosis, dopaminergic degeneration did not result in exacerbation of bone loss due to estrogen deficiency, but rather reduction of bone loss. Thus, this study provides evidence for the regulation of bone metabolism by the dopaminergic system through both gonadal steroid hormone-dependent and -independent functions, leading to possible early detection of osteoporosis development in individuals with PD.

Pharmacokinetics of Nanosomal Form of Levodopa in Intranasal Administration

BACKGROUND:

Parkinson’s disease is one of the most common neurological diseases. Pathogenesis of the disease is associated with destruction and death of neurons that produce the neurotransmitter dopamine. The precursor to dopamine, which crosses the protective blood-brain barrier, is the amino acid 3, 4-dihydroxy-L-phenylalanine – levodopa, L-DOPA. The investigational drug is a pharmaceutical composition, containing L-DOPA as an active substance, which is distributed in a polymer matrix based on a biodegradable copolymer of lactic/glycolic acids.

AIM:

This work aimed to study the main pharmacokinetic parameters for the drug “L-DOPA – PC, nasal drops” and comparator drugs “L-DOPA in oil”, “L-DOPA – PC in purified water”, reference product – tablets “Madopar 125”.

METHODS:

To increase the bioavailability of the active substance L-DOPA, a new route of administration was used for the first time – nasal administration. Pharmacokinetics of the innovative drug with the intranasal route of administration was investigated in rabbits. The L-DOPA concentration in blood plasma was determined by high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS).

RESULTS:

Bioavailability of the drug – nasal drops were 244.4% compared with the drug “Madopar 125”.

CONCLUSION:

Assay procedure for the determination of L-DOPA in animal blood plasma using liquid chromatography with tandem mass-selective detection (HPLC-MS/MS) was developed and validated.

The fate of thoracolumbar surgeries in patients with Parkinson's disease, and analysis of risk factors for revision surgeries

Background

Compared to patients without Parkinson’s disease (PD), patients with PD who underwent spinal surgeries were reported to have a relatively high complication rate. However, studies that analyze surgical risk factors for these patients are limited.

Methods

From October 2004 to April 2015, patients with PD who underwent spinal surgeries at our department were reviewed. Patients who underwent lumbar or thoracolumbar instrumented surgeries due to degeneration or deformity disease were included. Any reason for revision surgery was recorded. Risk factors including patients’ factors, surgical factors, and lumbo-pelvic radiographic parameters were analyzed. Patients’ factors included patients’ underlying diseases, body mass index (BMI), osteoporotic status, and PD’s severity using the modified Hoehn and Yahr staging scale. Surgical factors included surgical levels, extending to thoracic spine or not, corrective osteotomy, with anterior approach or not, and interbody device. Radiographic parameters included lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), coronal Cobb’s angles, and score for spino-pelvic realignment achievement.

Results

A total of 66 patients were enrolled. The mean age at surgery was 69.0 years old. The mean follow-up time was 51.2 months. Twenty-six revision surgeries were required in 19 patients (29%). Risk factors for revision surgery included modified Hoehn and Yahr stage ≥3 (p <  0.001), cancer history (p = 0.024), osteoporosis (P = 0.012) and underwent corrective osteotomy (p = 0.035). According to binary logistic regression analysis, the modified Hoehn and Yahr stage ≥3 (p <  0.001) was the only independent risk factor. The Kaplan-Meier analysis revealed patients with long instrumentation (surgical levels > 3), T-spine instrumentation, and lower score of spino-pelvic realignment achievement tended to have earlier revision.

Conclusion

For PD patients planning for elective thoracolumbar surgery, aggressive control status of PD before or after surgery is necessary to prevent surgical complications. Longer surgical levels and corrective osteotomy also tended to have earlier revision. A better score in spino-pelvic realignment achievement after surgery could reduce occurrence of revision.

Bone loss in MPTP mouse model of Parkinson's disease is triggered by decreased osteoblastogenesis and increased osteoclastogenesis

Bone loss is a non-motor symptom of Parkinson's disease (PD). It is unclear whether a patient's immobility or the endocrine changes in the body causes bone deterioration. To address this issue, we used an animal model of the disease where Swiss albino mice were injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on day 1 and were left untreated for eight weeks. Behavioral phenotypes of PD, and striatal acetylcholinesterase and dopamine levels were measured. Cortical and trabecular bones were assessed by μ-CT and histology. Gene expression studies were done through quantitative real-time PCR. Effect of MPP+ and MPTP-treated mice serum on MC3T3E-1, SH-SY5Y, and primary osteoclast cells were also studied. Our results demonstrated that MPTP treatment leads to PD like symptoms. It shows a loss of trabecular bone mass and quality by decreasing osteoblast and increased osteoclast number and activity. This effect was accompanied by reduced osteogenic and elevated osteoclastogenic genes expression. While MPP+ had a cytotoxic effect on dopaminergic neurons, it did not affect bone cells. However, ex-vivo treatment of the serum from MPTP-treated mice decreased osteoblastogenesis and increased osteoclastogenesis in cell culture. In conclusion, our study suggests that MPTP-induced parkinsonian features in mice leads to trabecular bone loss by decreased bone formation and increased bone resorption due to changes in the serum circulating factors. This study characterizes the microarchitectural and cellular changes in the skeleton of a mouse model of PD that can be further utilized to investigate therapeutic avenues to treat bone loss in PD patients.

Total Hip Arthroplasty in Patients With Parkinson Disease: Improved Outcomes With Dual Mobility Implants and Cementless Fixation

BACKGROUND

Parkinson disease (PD) results in severe limitation in ambulation caused by abnormality of gait and posture. The rate of complications, including fractures and dislocation after total hip arthroplasty (THA), can be higher among these patients. The goal of this study was to investigate the long-term outcomes of primary and revision THAs with cementless dual mobility implants.

METHODS

This retrospective study examines 59 PD patients who had surgery between 2002 and 2012. All the primary cases were performed for osteoarthritis and all patients received cementless acetabular implants with dual mobility bearing surface. The femoral stem was cemented in 4 patients who underwent revision surgery. The mean follow-up time was 8.3 years (4-14 years).

RESULTS

Good to excellent pain relief was achieved in 53 of 57 patients at the 2-year follow-up and in 40 of 47 patients at their latest follow-up. The most common medical complication was cognitive impairment (12 of 57 patients). One patient sustained an intraprosthetic hip dislocation 9 years after surgery, which required revision. Four patients sustained periprosthetic femoral fractures with well-fixed stem, requiring open reduction and internal fixation. The disability had increased in 68% of the patients in the latest follow-up visit.

DISCUSSION

Our study shows that elective primary or revision THA using cementless implants with dual mobility bearing surface in patients with PD provides satisfactory long-term outcomes, although many of these patients may see a general worsening of their activities over time due to PD.

Weight Loss and Malnutrition in Patients with Parkinson's Disease: Current Knowledge and Future Prospects

Parkinson's Disease (PD) is currently considered a systemic neurodegenerative disease manifested with not only motor but also non-motor symptoms. In particular, weight loss and malnutrition, a set of frequently neglected non-motor symptoms, are indeed negatively associated with the life quality of PD patients. Moreover, comorbidity of weight loss and malnutrition may impact disease progression, giving rise to dyskinesia, cognitive decline and orthostatic hypotension, and even resulting in disability and mortality. Nevertheless, the underlying mechanism of weight loss and malnutrition in PD remains obscure and possibly involving multitudinous, exogenous or endogenous, factors. What is more, there still does not exist any weight loss and malnutrition appraision standards and management strategies. Given this, here in this review, we elaborate the weight loss and malnutrition study status in PD and summarize potential determinants and mechanisms as well. In conclusion, we present current knowledge and future prospects of weight loss and malnutrition in the context of PD, aiming to appeal clinicians and researchers to pay a closer attention to this phenomena and enable better management and therapeutic strategies in future clinical practice.

Management of Spinal Conditions in Patients With Parkinson Disease

Parkinson disease (PD) is increasingly prevalent in the aging population. Spine disorders in patients with PD may be degenerative in nature or may arise secondary to motor effects related to the parkinsonian disease process. Physicians providing care for patients with PD and spine pathologies must be aware of several factors that affect treatment, including the patterns of spinal deformity, complex drug interactions, and PD-associated osteoporosis. Following spine surgery, complication rates are higher in patients with PD than in those without the disease. Literature on spine surgery in this patient population is limited by small cohort size, the heterogeneous patient population, and variable treatment protocols. However, most studies emphasize the need for preoperative optimization of motor control with appropriate medications and deep brain stimulation, as well as consultation with a movement disorder specialist. Future studies must control for confounding variables, such as the type of surgery and PD severity, to improve understanding of spinal pathology and treatment options in this patient population.

Osteoporosis: A Hidden Nonmotor Face of Parkinson's Disease

Osteoporosis is a "hidden nonmotor face" of Parkinson's disease and a cause of considerable morbidity in the older general population and in Parkinson's disease patients. Some regard this as a "hidden epidemic." Women are overrepresented and have considerable problems related to osteoporosis. In general osteoporosis leads to reduced mobility aggravating the motor syndrome of PD. The nonmotor aspects and impact of osteoporosis in PD have remained unexplored. Possible nonmotor consequences include a range of pain syndromes related to local pain, fractures, falls, and injuries as well as pathological fractures and radiculopathy. In addition depression, sleep dysfunction, dementia, as well as fear of falling also complicate the clinical picture. Quality of life deteriorates both for the patient and career. Pathways of care do not always include assessments for osteoporosis and needs to become obligatory particularly in older female PD patients. Active management strategies then need to be undertaken for osteoporosis in PD. Related motor and nonmotor consequences also highlight the importance of multidisciplinary treatment in PD particularly when dealing with osteoporosis.

Inhibitory Effects of Dopamine Receptor D1 Agonist on Mammary Tumor and Bone Metastasis

Dopaminergic signaling plays a critical role in the nervous system, but little is known about its potential role in breast cancer and bone metabolism. A screening of ~1,000 biologically active compounds revealed that a selective agonist of dopamine receptor D1 (DRD1), A77636, inhibited proliferation of 4T1.2 mammary tumor cells as well as MDA-MB-231 breast cancer cells. Herein, we examined the effect of A77636 on bone quality using a mouse model of bone metastasis from mammary tumor. A77636 inhibited migration of cancer cells in a DRD1-dependent fashion and suppressed development of bone-resorbing osteoclasts by downregulating NFATc1 through the elevation of phosphorylation of eIF2α. In the mouse model of bone metastasis, A77636 reduced osteolytic lesions and prevented mechanical weakening of the femur and tibia. Collectively, we expect that dopaminergic signaling might provide a novel therapeutic target for breast cancer and bone metastasis.

Auditing the Physical Activity and Parkinson Disease Literature Using the Behavioral Epidemiologic Framework

Motor and nonmotor symptoms associated with Parkinson disease place individuals at greater risk of sedentary behaviors and comorbidities. Physical activity is one modifiable means of improving health and reducing the risk of morbidity. We applied a behavioral framework to classify existing research on physical activity and Parkinson disease to describe the current evolution and inform knowledge gaps in this area. Research placed in phase 1 establishes links between physical activity and health-related outcomes; phase 2 develops approaches to quantify physical activity behavior; phase 3 identifies factors associated with implementation of physical activity behaviors; phase 4 assesses the effectiveness of interventions to promote activity; and phase 5 disseminates evidence-based recommendations. Peer-reviewed literature was identified by searching PubMed, Google Scholar, and EBSCO-host. We initially identified 287 potential articles. After further review, we excluded 109 articles, leaving 178 included articles. Of these, 75.84% were categorized into phase 1 (n = 135), 10.11% in phase 2 (n = 18), 9.55% into phase 3 (n = 17), 3.37% into phase 4 (n = 6), and 1.12% into phase 5 (n = 2). By applying the behavioral framework to the physical activity literature for people with Parkinson disease, we suggest this area of research is nascent with more than 75% of the literature in phase 1.

LEVEL OF EVIDENCE

III.