Screening and bioinformatics analysis of senile osteoporosis genes based on GEO database.

OBJECTIVE: Despite improvements in research on osteoporosis in the elderly, the specific mechanism remains unknown. In order to develop better treatment regimens with better efficacy and fewer adverse reactions (ARs), it is vital to unravel the pathogenesis of osteoporosis in the elderly. The GEO chip was used to screen differential genes in senile osteoporosis and analyze their interaction mechanisms in order to obtain potential therapeutic pathways and targets. MATERIALS AND METHODS: GSE35956 was downloaded from GEO database and used as the research object for KEGG pathway enrichment analysis, GO enrichment analysis and protein-protein interaction (PPI) network analysis, respectively, to explore the related mechanisms of the occurrence and development of osteoporosis in the elderly. RESULTS: There were 156 differentially expressed genes in the elderly (72 years old) and middle-aged (42 years old) diagnosed with osteoporosis, of which 6 were up-regulated and 150 were down-regulated. An analysis of gene enrichment using GO (gene body) revealed that differentially expressed genes (DEG) were mainly distributed in extracellular matrix (ECM) and other cell structures. Its functions include ossification, parathyroid hormone metabolism, multicellular biological signaling pathway, vitamin catabolism, interleukisn-5 metabolism, transmembrane transporter activity, receptor signaling pathway, calcium metabolism and other molecular functions. According to the Kyoto Encyclopedia of Genes and Genomes (KEGG), an online resource, signaling pathways associated with age-related osteoporosis (OP) are significantly enriched. The DEG enrichment pathways include Wnt, ECM-receptor interaction, cGMP-PKG, GAG degradation, and calcium signaling. A protein and protein interaction (PPI) network was constructed for 14 key genes, including CD44, GRIA1, KNG1 and IL7R. CONCLUSIONS: The findings of this study indicate that CD44, GRIA1, KNG1, IL7R, and other differential genes affect the Wnt signaling pathway in the elderly, which can provide new targets for the follow-up basic research and treatment of osteoporosis in the elderly.

Increased Sparc release from subchondral osteoblasts promotes articular chondrocyte degeneration under estrogen withdrawal.

OBJECTIVE: The incidence of osteoarthritis (OA) in menopausal women is significantly higher than in same-aged men. Investigating the role of subchondral osteoblasts in estrogen deficiency-induced OA may help elucidate the pathological mechanism, providing new insights for the diagnosis and treatment of menopausal OA. METHODS: A classical ovariectomy-induced OA (OVX-OA) rat model was utilized to isolate primary articular chondrocytes and subchondral osteoblasts, which were identified and then cocultured in Transwell. The expression of chondrocyte anabolic and catabolic indicators was evaluated. The differentially expressed proteins in the conditioned medium (CM) of osteoblasts were identified by Liquid Chromatograph-Mass Spectrometer (LC-MS/MS). Normal chondrocytes were treated with osteoblast CM, and then RNA sequencing was performed on the treated chondrocytes. KEGG was used to identify significant enrichment of signaling pathways, and Simple Western was used to verify the expression of related proteins in the signaling pathways. RESULTS: Coculture of OVX-OA subchondral osteoblasts with chondrocytes significantly downregulated the expression of the anabolic indicators and upregulated the expression of the catabolic indicators in chondrocytes. 1,601 proteins were identified in both normal and OVX osteoblast culture supernatants. Protein-protein interaction network analysis revealed that Sparc was one of the hub proteins. The AMPK/Foxo3a signaling pathway of chondrocytes was downregulated by OVX-OA osteoblasts CM. AICAR, the AMPK agonist, partially reversed the catabolic effect of OVX-OA osteoblasts on chondrocytes. CONCLUSIONS: Sparc secreted by OVX-OA subchondral osteoblasts can downregulate the AMPK/Foxo3a signaling pathway of chondrocytes, thereby promoting chondrocyte degeneration.

The effect of BMP2/Smads pathway mediating platelet-rich fibrin on rat bone mesenchymal stem cells.

OBJECTIVE: We explored the influences on platelet-rich fibrin (PRF) to rat Bone Mesenchymal Stem Cells (BMSCs), as well as the role of bone morphogenetic protein 2 (BMP2)/maternal signal protein homolog (Smads) pathway. MATERIALS AND METHODS: The proposed research is approved by the ethics board of the Second Affiliated Hospital of Harbin Medical University. The BMSCs were isolated and purified. The BMSCs were assigned to a control group arbitrarily, PRF group, BMP activator group and BMP inhibitor group (hereinafter referred to as activator group and inhibitor group). Each group of BMSCs in the logarithmic growth phase was detected for the alkaline phosphatase (ALP) activity since 3 days and 14 days of culture; CCK-8 assay was conducted for detection of the proliferation of BMSCs; Real time PCR was conducted for detection of the osteogenic differentiation marker collagen I (COL-I), BMP2, Runt-related transcription factor 2(RUNX2), osteocalcin (OCN) mRNA relative expression levels; Western-Blot detection of BMP2, OCN, P-SMAD1/5/8, relative expression level of RUNX2 protein. RESULTS: In contrast to the control group, BMSCs' the ALP activity of the PRF group, activator group, as well as inhibitor group increased for 3 days and 14 days, and the activator group>PRF group>inhibitor group (p≤0.05). ALP activity in each group was elevated with the increase in culture time, the ALP activity of the control group, PRF group, activator group and inhibitor group increased (p≤0.05). In comparison to the control group, the relevant expression levels of COL-I, BMP-2, RUNX2 and OCN in the PRF group, activator group, and inhibitor group increased, and the activator group>PRF group>inhibitor group (p≤0.05). The relative expression levels of BMP2, OCN, p-SMAD1/5/8 and RUNX2 protein in each group were statistically different, the activator group>PRF group>control group>inhibitor group (p≤0.05). CONCLUSIONS: PRF can promote the proliferation and osteogenic differentiation of BMSCs by activating the BMP2/Smads signaling pathway.

[Progress of research regarding the influenza early warning system, based on "Big Data"].

Shortcomings have been inherited in the traditional influenza early warning system, often expressed through the scope, accuracy on prediction and real-time performance of the monitor related programs. With the new round of scientific and technological revolution and the increasingly maturity of modern information system, related technology on influenza early warning has become the focus of research in this field, based on big data analysis technology. Using the traditional influenza surveillance and early warning system as reference, this paper summarizes the progress of influenza early warning research, based on the Internet, influencing factors, time and space trends, and risk assessment etc., to summarize the trends on the advantages, shortcomings and future development of big data, used in the early warning system on influenza.

Superconductivity under pressure in the Dirac semimetal PdTe2.

The Dirac semimetal PdTe2 was recently reported to be a type-I superconductor (T c = 1.64 K, [Formula: see text] mT) with unusual superconductivity of the surface sheath. We here report a high-pressure study, [Formula: see text] GPa, of the superconducting phase diagram extracted from ac-susceptibility and transport measurements on single crystalline samples. T c (p ) shows a pronounced non-monotonous variation with a maximum T c = 1.91 K around 0.91 GPa, followed by a gradual decrease to 1.27 K at 2.5 GPa. Surface superconductivity is robust under pressure as demonstrated by the large superconducting screening signal that persists for applied dc-fields [Formula: see text]. Surprisingly, for [Formula: see text] GPa the superconducting transition temperature at the surface [Formula: see text] is larger than T c of the bulk. Therefore surface superconductivity may possibly have a non-trivial topological nature. We compare the measured pressure variation of T c with recent results from band structure calculations and discuss the importance of a Van Hove singularity.

[Horizontal semicircular canals light cupulopathy: 2 cases report].

SummaryAnalyze 2 cases of horizontal semicircular canals light cupulopathy patient history, clinical manifestations, vestibular function and hearing test results, summarize the clinical features of the disease. All of the 2 patients showed a typicaln light cupulopathy nystagmus. That is, the nystagmus of the Roll-Test test is sustained to the ground, and there is no latency and attenuation with null plane. When the patient's nystagmus is characterized by direction changing positional nystagmus and head deflection nystagmus disappearance（null plane）, the possibility of horizontal semicircular canals light cupulopathy is to be thought of. In this paper, 2 cases of horizontal semicircular canals light cupulopathy received in our hospital are reported as follows.

[Gene diagnosis and treatment of hereditary hemorrhagic telangiectasia with epistaxis as its main symptom].

Objective:The aim of this study is to investigate the gene diagnosis and the treatment of hereditary hemorrhagic telangiectasia (HHT) with epistaxis as the main symptom, and to analyze the mutation of ACVRL1 gene in the family. Method:Detailed pedigree investigation was carried out on the proband.Sixtynine genes related to coagulation disorder were sequenced and analyzed by high throughput sequencing for the father and son of the proband. Result:Four generations of the family consisted of 30 probands, including 11 patients. A pathogenic mutation ACVRL1_ex9 c.1313T > C (p.M438T) was detected in both patient and his father. Conclusion:Recurrent epistaxis is the main manifestation of hereditary hemorrhagic telangiectasia in this family. The mutation of ACVRL1 gene is the pathogenic gene of this family, which can be treated by surgery and medicine.

[Effect of modified body position on cVEMP in normal young people].

Objective: To observe the effect of modified body position on cervical vestibular evoked myogenic potential(cVEMP) in normal young people. Method: Thirty normal young people were selected as subjects. CVEMP test was performed by supine head position and sitting submandibular lower body position respectively. The cVEMP examination results were observed and compared. Result: The elicitation rate of the two kinds of position of cVEMP were 100%. There was no significant difference in P1 latency, N2 latency, amplitude and asymmetry ratio. Different body position comfort VAS score, submandibular pressure of sitting position was better than supine head up position(P<0.05). Conclusion: Submandibular pressure of sitting position has no effect on the results of cVEMP examination, and the subjects are more comfortable, and can be used for old age and inability to cooperate with supine head up position.

Penetration depth study of the type-I superconductor PdTe2.

Superconductivity in the topological non-trivial Dirac semimetal PdTe2 was recently shown to be type-I. We hereby report measurements of the relative magnetic penetration depth, [Formula: see text], on several single crystals using a high precision tunnel diode oscillator technique. The temperature variation [Formula: see text] follows an exponential function for [Formula: see text], consistent with a fully-gapped superconducting state and weak or moderately coupling superconductivity. By fitting the data we extract a [Formula: see text]-value of ∼500 nm. The normalized superfluid density is in good agreement with the computed curve for a type-I superconductor with nonlocal electrodynamics. Small steps are observed in [Formula: see text], which possibly relates to a locally lower [Formula: see text] due to defects in the single crystalline sample.

[Rasmussen syndrome: a clinicopathologic study of four cases].

Objective: To investigate the clinicopathologic features of Rasmussen syndrome (RS) and to raise awareness of this rare disease. Methods: Clinicopathologic data of 4 cases of RS were retrospectively analyzed at Beijing Haidian Hospital from 2008 to 2016. Results: The clinical manifestations included epilepsia partialis continua and progressive neurologic deficits in all patients.MRI demonstrated unihemispheric focal cortical atrophy in all cases. The histopathologic changes included variable degrees of lymphocytic infiltrate within the cortex, subarachnoid space and perivascular cuffing.Microglial nodules and neuronophagia were seen. Mild to severe neuronal loss was noted with variable degrees of reactive gliosis. Spongy edema and cavitation were observed in focal cortex. Inflammation involving hippocampus was seen in one case. Three cases were accompanied by focal cortical dysplasia (FCD) Ⅲd. Immunohistochemical staining showed that the infiltrative lymphocytes were positive for CD3, CD8, granzyme B and TIA1 and the proliferating microglial cells were positive for CD68. NeuN positive neurons decreased significantly and reactive astrocytes were GFAP positive. Conclusions: Pathologic changes of RS are similar to viral encephalitis and the inflammation is progressive and multifocal involving the hemisphere. The diagnosis of RS relies on pathologic features combined with clinical findings and neuroradiological examinations.

[Three-dimensional architecture of intraosseous vascular anatomy of the hamate: a micro-computed tomography study].

OBJECTIVE: To obtain three-dimensional intraosseous artery of the hamate and to provide the vascular anatomy basis of hamate fracture fixation. METHODS: PbO (lead monoxide, Sinopharm Chemical Reagent Beijing Co. Ltd) was ground into particles less than 40 µm and suspended in turpentine oil (Chemical Reagent Beijing Co. Ltd) at ratios of 1 g : 1.5 mL, 1 g : 1 mL and 1 g : 0.5 mL. Three specimens were investigated. Brachial arteries were cannulated and perfused with lead-based contrast agent. Hamates were harvested and scanned using micro-computed tomography (microCT). The acquisition protocols were as follows: CT scan setup: total rotation [Degrees], 360; rotation steps, 360; X-ray detector setup: transaxial, 2048; axial, 2048; exposure time, 1 500 ms, Binning, 1; system magnification: high-med. X-ray tube setup: 80 kV, 500 mA current. The down-sampling factor used in the reconstruction was 2. The effective voxel size of the final image was 27.30 µm. The three-dimensional model of the hamate was generated and the distribution and pattern of vessels were evaluated. RESULTS: There were abundant extraosseous vessels around the hamate. They were mainly running in the tendons and ligaments around the hamate. Four vascular zones were identified on the hamate surface. They were on the palmar platform of the hamate body, on the dorsal side, on the ulnar side and on the tip of hamulus, namely. There were anastomoses among 4 vascular zones. We did not observe any vessels penetrating through the articular cartilage. The extraosseous vessels of the vascular zones gave a number of intraosseous branches into the hamate. The hamate body received intraosseous blood supply from the dorsal, palmar and ulnar while the hamulus from the palmar, ulnar and hamulus tip. There were some intraosseous branches anastomosing with each other. CONCLUSION: The extraosseous and intraosseous vessels of the hamate were more than what used to be considered. The hamate body and hamulus received blood supply from multiple directions and arteries anastomosed extensively both outside and inside the hamate, making it possible that the intraosseous perfusion survived after fracture. It is likely that the nonunion after the hamate fracture is not caused by the vascular damage but the malalignment of the fragments.

Intraosseous Injection of Simvastatin in Poloxamer 407 Hydrogel Improves Pedicle-Screw Fixation in Ovariectomized Minipigs.

BACKGROUND: Osteoporosis leads to poor osseointegration and reduces implant stability. Statins have been found to stimulate bone formation, but the bioavailability from oral administration is low. Local application may be more effective at augmenting bone formation and enhancing implant stability. This study was performed to evaluate the efficacy of an intraosseous injection of simvastatin in thermosensitive poloxamer 407 hydrogel to enhance pedicle-screw fixation in calcium-restricted ovariectomized minipigs. METHODS: Nine mature female Guangxi Bama minipigs underwent bilateral ovariectomy and were fed a calcium-restricted diet for 18 months. Simvastatin (0, 0.5, or 1 mg) in thermosensitive poloxamer 407 hydrogel was injected into the lumbar vertebrae (L4-L6), and titanium alloy pedicle screws were implanted. Bone mineral density (BMD) measurements of the lumbar vertebrae were determined by dual x-ray absorptiometry (DXA) before and 3 months after treatment. The lumbar vertebrae were harvested and analyzed with use of microcomputed tomography, biomechanical pull-out testing, histological analysis, and Western blot analysis for bone morphogenetic protein (BMP)-2 and vascular endothelial growth factor (VEGF) expression. RESULTS: Evaluation over a 3-month study period demonstrated that the BMD of the vertebrae injected with 0.5 and 1.0 mg of simvastatin had increased by 31.25% and 31.09%, respectively, compared with vehicle-only injection (p ≤ 0.00014 for both) and increased by 32.12% and 28.16%, respectively, compared with the pre-treatment levels (p < 0.0001 for both). A single injection of simvastatin in poloxamer 407 increased trabecular volume fraction, thickness, and number and decreased trabecular separation (p ≤ 0.002). The bone formation and mineral apposition rates significantly increased (p ≤ 0.023). The percentage of osseointegration in the simvastatin 0.5 and 1-mg groups was 46.54% and 42.63% greater, respectively, than that in the vehicle-only group (p ≤ 0.006), and the maximum pull-out strength was 45.75% and 51.53% greater, respectively, than in the vehicle-only group (p ≤ 0.0005). BMP-2 and VEGF expressions were higher than for the vehicle-only injection. CONCLUSIONS: A single intraosseous injection of simvastatin in thermosensitive poloxamer 407 hydrogel stimulated bone formation, increased BMD, improved bone microstructure, promoted osseointegration, and significantly enhanced the stability of pedicle screws in calcium-restricted ovariectomized minipigs. CLINICAL RELEVANCE: These results provide rationale for evaluating intraosseous injection of simvastatin in poloxamer 407 to enhance implant fixation in patients with osteoporosis.

[Reported of 2 cases relapsing polychondritis].

Clinical data of two cases of relapsing polychondritis were reported and the relative literatures were reviewed. The two patients diagnosed relapsing polychondritis after clinical and laboratory examinations.The first case was mild , no larynx and trachea involvement, and her condition improved and controlled after glucocorticoid treatment;The second case which involved larynx and trachea caused breathing difficulty. Two years later he died of lung infection and respiratory failure despite a variety of treatment methods. Relapsing polychondritis is very easily misdiagnosed, early diagnosis and treatment can slow the progression of the disease, for patients with violations of the larynx and trachea should pay close attention to disease progression, tracheotomy or place endotracheal memory alloy stent when necessary.

A single CT-guided percutaneous intraosseous injection of thermosensitive simvastatin/poloxamer 407 hydrogel enhances vertebral bone formation in ovariectomized minipigs.

UNLABELLED: The ultimate goal of osteoporosis treatment is prevention of fragile fracture. Local treatment targeting specific bone may decrease the incidence of osteoporotic fractures. We developed an injectable, thermosensitive simvastatin/poloxamer 407 hydrogel; a single CT-guided percutaneous intraosseous injection augmented vertebrae in ovariectomized minipigs. INTRODUCTION: The greatest hazard associated with osteoporosis is local fragility fractures. An adjunct, local treatment might be helpful to decrease the incidence of osteoporotic fracture. Studies have found that simvastatin stimulates bone formation, but the skeletal bioavailability of orally administered is low. Directly delivering simvastatin to the specific bone that is prone to fractures may reinforce the target bone and reduce the incidence of fragility fractures. METHODS: We developed an injectable, thermosensitive simvastatin/poloxamer 407 hydrogel, conducted scanning electron microscopy, rheological, and drug release analyses to evaluate the delivery system; injected it into the lumbar vertebrae of ovariectomized minipigs via minimally invasive CT-guided percutaneous vertebral injection. Three months later, BMD, microstructures, mineral apposition rates, and strength were determined by DXA, micro-CT, histology, and biomechanical test; expression of VEGF, BMP2, and osteocalcin were analyzed by immunohistochemistry and Western blots. RESULTS: Poloxamer 407 is an effective controlled delivery system for intraosseous-injected simvastatin. A single injection of the simvastatin/poloxamer 407 hydrogel significantly increased BMD, bone microstructure, and strength; the bone volume fraction and trabecular thickness increased nearly 150 %, bone strength almost doubled compared with controls (all P < 0.01); and induced higher expression of VEGF, BMP2, and osteocalcin. CONCLUSIONS: CT-guided percutaneous vertebral injection of a single simvastatin/poloxamer 407 thermosensitive hydrogel promotes bone formation in ovariectomized minipigs. The underlying mechanism appears to involve the higher expression of VEGF and BMP-2.

Vitamin D prevents articular cartilage erosion by regulating collagen II turnover through TGF-ß1 in ovariectomized rats.

OBJECTIVE: To explore the effect of vitamin D on turnover of articular cartilage with ovariectomy (OVX) induced OA, and to investigate transforming growth factor-ß1 (TGF-ß1) as a possible underlying mechanism mediated by 1α,25(OH)2D3. DESIGN: Sixty-six rats were randomly allocated into seven groups: sham plus control diet (SHAM+CTL), OVX+CTL diet, sham plus vitamin D-deficient (VDD) diet, OVX+VDD diet, and three groups of ovariectomized rats treated with different doses of 1α,25(OH)2D3. The cartilage erosion and the levels of serum 17ß-estradiol, 1α,25(OH)2D3 and C-telopeptide of type II collagen (CTX-II) were measured. TGF-ß1, type II Collagen (CII), matrix metalloproteinases (MMP)-9,-13 in articular cartilage were assessed by immunohistochemistry. TGF-ß1 and CTX-II expression were measured in articular cartilage chondrocytes treated with/without tumor necrosis factor (TNF-α), 1α,25(OH)2D3, and TGF-ß receptor inhibitor (SB505124) in vitro. RESULTS: Cartilage erosion due to OVX was significantly reduced in a dose-dependent manner by 1α,25(OH)2D3 supplementation, and exacerbated by VDD. The expressions of TGF-ß1 and CII in articular cartilage were suppressed by OVX and VDD, and rescued by 1α,25(OH)2D3 supplementation. The expression of MMP-9,-13 in articular cartilage increased with OVX and VDD, and decreased with 1α,25(OH)2D3 supplementation. In vitro experiments showed that 1α,25(OH)2D3 increased the TGF-ß1 expression of TNF-α stimulated chondrocytes in a dose-dependent manner. 1α,25(OH)2D3 significantly counteracted the increased CTX-II release due to TNF-α stimulation, and this effect was significantly suppressed by SB505124. CONCLUSION: VDD aggravated cartilage erosion, and 1α,25(OH)2D3 supplementation showed protective effects in OVX-induced OA partly through the TGF-ß1 pathway.

Combined non-pharmacological interventions for newborn pain relief in two degrees of pain procedures: A randomized clinical trial.

BACKGROUND: Non-pharmacological interventions are effective neonatal pain reduction strategies. We aimed to study the effects of non-nutritive sucking (NNS) and swaddling on infants' behavioural and physiological parameters during shallow or deep heel stick procedures. METHOD: In this prospective, multi-centred, randomized controlled clinical trial, we enrolled 671 newborns. The infants undergoing shallow or deep heel stick procedures were randomized into four groups: oral sucrose (routine care, group S), oral sucrose combined with NNS (group NS), oral sucrose combined with swaddling (group SS) and oral sucrose combined with NNS and swaddling (group NSS). The behavioural responses were evaluated by the Revised Neonatal Facial Coding System and the physiological signals were monitored by electrocardiogram monitors. RESULTS: A significant synergistic analgesic effect was observed between the NS and SS groups in both the shallow (F = 5.952, p = 0.015) and deep heel stick (F = 7.452, p = 0.007) procedure. NSS group exhibited the lowest pain score. For the deep heel stick procedure, the NS group had a significantly lower increase in heart rate (HR)% and decrease in SPO2 % than the S group (F = 17.540, p = 0.000, F = 10.472, p = 0.001), while this difference was not observed in the shallow heel stick procedure. No difference was found between the S and SS groups, in terms of different physiological parameters. CONCLUSION: Non-nutritive sucking and swaddling had synergistic effects on pain relief when used with oral sucrose. For the deep heel stick procedure, oral sucrose combined with NNS and swaddling provided the best pain relief effect. For the shallow heel stick procedure, addition of NNS and swaddling did not improve the effects.

Pitted keratolysis: a clinical review.

BACKGROUND: Pitted keratolysis is a bacterial infection that affects the plantar epidermis. Despite the condition being reported in many countries affecting both shod and unshod populations, there is little guidance for clinicians providing evidence or best practice guidelines on the management of this often stubborn infection. METHODS: Using a structured search of a range of databases, papers were identified that reported treatments tested on patients with the condition. RESULTS: Most of the literature uncovered was generally of a low level, such as case-based reporting or small case series. Studies were focused mainly on the use of topical antibiotic agents, such as clindamycin, erythromycin, fusidic acid, and mupirocin, often in combination with other measures, such as hygiene advice and the use of antiperspirants. From the limited evidence available, the use of topical antibiotic agents shows some efficacy in the treatment of pitted keratolysis. However, there is currently no suggestion that oral antibiotic drug therapy alone is effective in managing the condition. CONCLUSIONS: Currently, there is no consensus on the most effective approach to managing pitted keratolysis, but a combination of antimicrobial agents and adjunctive measures, such as antiperspirants, seems to demonstrate the most effective approach from the current literature available.

Compact engineering of path-entangled sources from a monolithic quadratic nonlinear photonic crystal.

An integrated realization of photonic entangled states becomes an inevitable tendency toward integrated quantum optics. Here we report the compact engineering of steerable photonic path-entangled states from a monolithic quadratic nonlinear photonic crystal. The crystal acts as a coherent beam splitter to distribute photons into designed spatial modes, producing the heralded single-photon and appealing beamlike two-photon path entanglement. We characterize the path entanglement by implementing quantum spatial beating experiments. Such a multifunctional entangled source can be further extended to the high-dimensional fashion and multiphoton level, which paves a desirable way to engineering miniaturized quantum light sources.

Dietary sources of animal and plant protein intake among Flemish preschool children and the association with socio-economic and lifestyle-related factors.

BACKGROUND: The aims of this study were to assess the intake of animal, plant and food group-specific protein, and to investigate their associations with socio-economic and lifestyle-related factors in Flemish preschoolers. METHODS: Three-day estimated dietary records were collected from 661 preschoolers aged 2.5-6.5 y (338 boys and 323 girls). Multiple linear regression analysis was used to investigate the association between animal, plant, and food group-specific protein intake and socio-economic and lifestyle factors. RESULTS: Animal proteins (mean 38 g/d) were the main source of total protein (mean 56 g/d), while mean plant protein intake amounted to 18 g/d. The group of meat, poultry, fish and eggs was the main contributor (51%) to animal protein intake, followed by milk and milk products (35%). Bread and cereals (41%) contributed most to the plant protein intake, followed by low-nutritious, energy-dense foods (21%). With higher educated fathers and mothers as reference, respectively, preschoolers with lower secondary and secondary paternal education had lower animal, dairy-, and meat-derived protein intakes, and those with lower secondary and secondary maternal education consumed less plant, and bread and cereal-derived proteins. Compared to children with high physical activity levels, preschoolers with low and moderate physical activity had lower animal and plant protein intakes. Significantly higher potatoes and grains-, and fish- derived proteins were reported for children of smoking mothers and fathers, respectively, compared to those of non-smoking mothers and fathers. CONCLUSIONS: The total protein intake of Flemish preschoolers was sufficient according to the recommendations of the Belgian Superior Health Council. Parental level of education and smoking status might play a role in the sources of children's dietary proteins.