A real-world pharmacovigilance study of abaloparatide based on the FDA Adverse Event Reporting System (FAERS).

Abaloparatide (ABL) is a US Food and Drug Administration-approved parathyroid hormone-related peptide analog for treatment of osteoporosis in postmenopausal women at high risk of fracture. However, real-world data regarding its long-term safety and tolerability in large sample population are incomplete. We evaluated abaloparatide-associated safety signals by data mining of the FDA pharmacovigilance database. INTRODUCTION: We investigated 33,480(0.14%) ABL-related adverse events (AEs) through data mining of Food and Drug Administration Adverse Event Reporting System (FAERS) retrospectively. METHODS: Reporting odds ratio (ROR), the proportional reporting ratio (PRR), the Bayesian confidence propagation neural network (BCPNN), and the multi-item gamma Poisson shrinker (MGPS) were employed to quantify the signals of ABL-related AEs from 2017Quarter2 to 2022.Serious and non-serious cases were compared by Mann-Whitney U test or Chi-squared (χ2) test. RESULTS: We collected 8,470,497 reports from the FAERS database, including 11,487 reports defined ABL as the primary suspected (PS) drug. Additionally, 36.16% of the reports were submitted by healthcare professionals (n=4154), compared to 62.26% reported by consumers (n=7140). A total 99 signals simultaneously conforming to four algorithms were detected, among which, 35 signals were identified as unexpected signals. Such as growing pains (n=13), waist circumference increased (n=21), sensory disturbance (n=103), tinnitus (n=65), visual acuity reduced (n=54), blood alkaline phosphatase increased (n=61), and hair growth abnormal (n=13). Patient age (p < 0.001) might be associated with an increased risk of AEs severity. The most common timeframe for AE occurrence was 0-7 days. CONCLUSION: Our study provided a deeper and broader understanding of abaloparatide's safety profiles, which would help healthcare professionals to mitigate the risk of AEs in clinical practice, a low number of unexpected AEs supporting ongoing additional pharmacovigilance.

[The impact of obstructive sleep apnea hypopnea syndrome on the perioperative and long-term outcome in patients with Stanford type A aortic dissection].

Objective: To confirm the impact of obstructive sleep apnea hypopnea syndrome (OSAHS) on perioperative and long-term outcome in patients with Stanford type A aortic dissection. Methods: From June 2010 to July 2017, the clinical data of 91 patients with Stanford type A aortic dissection were analyzed. Among them, 51 patients with OSAHS were included in the study group and 40 patients without OSAHS were included in the control group. After 36 months follow-up, all-cause death was regarded as the end event. The clinical baseline data, perioperative period and 36 months survival rate of the two groups were compared. Kanplan-Meier method was used to describe the 36 month survival curve of the two groups. Cox proportional risk model was used to evaluate the risk ratio (HR) and 95%CI of 36 month survival rate. Results: The mortality rate during hospitalization was 5.9% (3 cases) in the study group and 5.0% (2 cases) in the control group, and the difference was not statistically significant (χ~2=0.03, P>0.05). The actual follow-up was (36.2±1.5) months, 88 cases were followed up and 3 cases were lost. The all cause mortality rate of 36 months was 27.5% (14/51)in the study group and 10.0%(4/40) in the control group, the difference was statistically significant (χ~2=4.30, P<0.05).By Cox proportional risk model analysis, 36 months after operation, the study group was compared with the control group after adjusting for age, male, bicuspid of aortic valve, chronic obstructive pulmonary disease, anemia, preoperative pericardial tamponade, postoperative organ dysfunction, preoperative LVEF, emergency operation, Sun's operation, coronary artery bypass grafting, hypertension, cardiac arrhythmia, and advanced avulsion of distal aortic dissection The survival rate was lower, the difference was statistically significant (P<0.05).In addition to OSAHS, coronary artery bypass grafting and preoperative pericardial tamponade were also risk factors for the increase of 36 month mortality rate (HR=11.28,95%CI: 1.98-46.25, P=0.009; HR=9.08, 95%CI: 2.22-41.3, P=0.032). Conclusions: There was no significant difference in mortality during hospitalization in patients with Stanford A aortic dissection combined with OSAHS. The survival rate of 36 months after operation was lower than that of the control group.

[Application of fecal DNA methylation biomarkers detection in gastric cancer screening].

Objective: Explore the feasibility of fecal gene methylation for screening gastric cancer and its relationship with clinical characteristics of gastric cancer patients. Methods: One hundred and fifty-six stool samples of patients in general surgery or digestive department of the First Affiliated Hospital of Soochow University from August 2018 to December 2019 were collected, detailed clinical information of gastric cancer patients were recorded. All patients and normal controls were divided into two sets including train sets (n=52)and test sets (n=104). Stool DNA was extracted for detection of methylation (SDC2, SFRP2, RASSF2 and TERT). Meanwhile, hemoglobin in stool samples were detected by immunoassays. A logistic regression model was built to analyze the sensitivity and specificity of single fecal DNA biomarker in detecting gastric cancer by Ct values of each stool-based DNA biomarker; Based on Akaike information criterion (AIC), the gastric cancer early screening model was constructed with each biomarker and the combinations, and evaluate the performance of the model in the test sets. Results: The accuracy of each stool biomarkers and their ranks were showed as SDC2(71.2%)>TERT(67.3%)=RASSF2(67.3%)>Hb(63.5%)>SFRP2(61.5%). By stepwise regression analysis, a combination composed of the methylation of SDC2 and TERT, fecal occult blood testing was well-behaved in the screening of gastric cancer.This combination showed a sensitivity of 66.7% for gastric cancer in train sets and test sets at the specificity of 78.9%. In different stages and parts of gastric cancer samples, the combination of this marker has the highest sensitivity in stage I gastric cancer(78.6%) and gastric body cancer(75.0%). Conclusion: The methylation of SDC2, SFRP2, TERT, RASSF2 has higher accuracy rate in the screening of gastric cancer, which is a potential fecal biomarker of gastric cancer.

Outcomes of self-expandable metal stent placement for malignant oesophageal strictures.

AIM: To analyse the outcomes of oesophageal stenting for malignant strictures and to study the correlation between the follow-up time and major complications. MATERIALS AND METHODS: Patients with oesophageal malignancy who underwent stent placement between 2011 and 2016 for dysphagia were included. The data included age, sex, dysphagia, length and location of stenosis, date of stent placement, complications, follow-up time, and survival. RESULTS: Two hundred and ninety-eight patients were included in the study. Minor complications occurred in 113 patients (37.9%) including chest pain (17.1%), foreign body sensation (25.5%), hiccups (1.68%), and reflux symptoms (27.5%). Major adverse events occurred in 93 (31.1%) patients including pneumonia (25.5%), migration (3%), perforation (0.67%), bleeding (1.68%), and restenosis (22.5%). oesophago-airway fistula occurred in 45 (15.1%) patients. The incidence of recurrent dysphagia, pneumonia, and oesophago-airway fistula increased over 3 months and decreased after another 3 months. The incidence of major complications as a percentage of survivors remained high after 3 months (>40%). Spearman analysis revealed a significant positive correlation between the incidence and the follow-up time over this period (rs=0.907, p<0.01). CONCLUSION: The major complications of oesophageal stenting increased with time over 3 months and remained high for another 3 months. Therefore, stenting should be considered for palliation in patients with short expected survival (usually <3 months).

Effects of astaxanthin onaxonal regeneration via cAMP/PKA signaling pathway in mice with focal cerebral infarction.

OBJECTIVE: To investigate the effect of astaxanthin on the neurological function of the middle cerebral artery occlusion (MCAO) mice and its possible mechanism. MATERIALS AND METHODS: The male C57BL/6 mice were selected to establish the model of MCAO via electrocoagulation, and they were randomly divided into 4 groups: the sham operation group (Sham group), the cerebral ischemia model group (MCAO group), the astaxanthin intervention group (gavage with 30 mg/kg astaxanthin for 28 days, twice a day; Ast group), and astaxanthin + H89 group (Ast + H89 group). At 3, 7, 14, and 28 d after the operation, the Rotarod test and the balance beam footstep error test were performed. The brain tissues were taken for immunofluorescence to observe the expression of the growth-associated protein 43 (GAP43) in the cortex around the infarction. The GAP43 protein and mRNA levels in the cortex around the infarction were detected via Western blotting, and the Reverse Transcription-Polymerase Chain Reaction (RT-PCR), the levels of cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) in the bilateral cerebral cortex were detected via enzyme-linked immunosorbent assay (ELISA), and the PKAc and phosphorylated-cAMP-response element-binding protein (p-CREB) levels in the bilateral cerebral cortex were detected via Western blotting. Biotin dextran amine (BDA) was injected at 14 d after the operation, and the brain was taken at 28 d. The BDA-labeled neurons or axons were observed in the bilateral cortex via immunohistochemistry and immunofluorescence, and the colocalization of BDA and GAP43 in the cortex around the infarction was observed using double immunofluorescence staining. RESULTS: Compared with those in the MCAO group, the mean residence time in the Rotarod test was significantly increased, and the times of the footstep error on the balance beam were significantly reduced in the Ast group. In the Ast group, the expression of GAP43 in the cortex around the infarction, the GAP43 protein, and the mRNA levels were all significantly elevated. Immunofluorescence showed that in the Ast group, the number of the labeled neurons and axons in the bilateral cortex was slightly larger than that in the other groups, and the number of labeled axonal fibers in the ischemic cortex was significantly increased. The colocalization area of BDA and GAP43 was observed, and it was found that the positive area in the Ast group was significantly larger than that in the MCAO group. The cAMP level was higher in the Ast group and Ast + H89 group at 7, 14, and 28 d after operation, while the PKA level was lower in the Ast + H89 group at 7 and 14 d after operation and higher in the Ast group at 7, 14, and 28 d after operation. The results of the Western blotting manifested that the PKAc and p-CREB levels were upregulated in the Ast group at 7, 14, and 28 d after the operation, and downregulated in the Ast + H89 group at 7, 14, and 28 d after the operation. CONCLUSIONS: Astaxanthin activates the cAMP/PKA/CREB signaling pathway by increasing the cAMP concentration in brain tissues, ultimately promoting the axonal regeneration in the cerebral cortex and improving the motor function.

Autologous oxygen release nano bionic scaffold composite miR-106a induced BMSCs enhances osteoblast conversion and promotes bone repair through regulating BMP-2.

OBJECTIVE: Suitable seed cells and selection of bioactive scaffold materials are the main research contents of bone tissue engineering. It was showed that autologous oxygen release nano bionic scaffold could promote the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). The role of microRNA-106a (miR-106a) in regulating BMSCs differentiation has not been reported. We intend to investigate the role of autologous oxygen release nano bionic scaffold composite miR-106a in inducing BMSCs constructing tissue engineering bone. MATERIALS AND METHODS: Rat BMSCs were isolated and transfected by using miR-106a scramble or miR-106a inhibitor. Healthy male Sprague-Dawly (SD) rats were randomly divided into three groups, including bone fracture group established as rat tibial fracture model, negative control group implanted by autologous oxygen release nano bionic scaffold composite miR-106a scramble BMSCs, and miR-106a inhibitor group implanted by autologous oxygen release nano bionic scaffold composite miR-106a inhibitor BMSCs. Callus growth was observed. Alkaline phosphatase (ALP) activity was detected. Bone morphogenetic protein 2 (BMP-2) expression was tested by Real-time PCR (RT-PCR) and Western blot assay. Collagen II production was determined by RT-PCR. RESULTS: Autologous oxygen release nano bionic scaffold composite BMSCs significantly increased local bone mineral density, promoted callus healing, facilitated ALP secretion, elevated collagen II expression, and up-regulated BMP-2 mRNA and protein levels compared with fracture group (p<0.05). Autologous oxygen release nano bionic scaffold composite miR-106a induced BMSCs exhibited more significant effect on bone repair (p<0.05). CONCLUSIONS: Autologous oxygen release nano bionic scaffold composite miR-106a induced BMSCs enhanced osteoblast conversion and promoted bone repair through regulating BMP-2.

[Similar coronal curvature may not represent the same 3-dimensional deformity in adolescent idiopathic scoliosis: a matched-pair study using EOS imaging system].

Objective: To analyze the preoperative axial plane and the surgical outcomes of the Lenke type 1A patients with adolescent idiopathic scoliosis (AIS) whose coronal curve type was matched but thoracic kyphosis (TK) was different. Methods: This study retrospectively reviewed a series of Lenke type 1A female AIS patients who underwent corrective surgery in the Department of Spine Surgery of Nanjing Drum Tower Hospital from May to August 2017. After matched with the Cobb angle of the main thoracic curve, the apical vertebral, the vertebra number included in the curve, the lumber modifier in the Lenke classification and Risser sign, 12 pairs of AIS patients, whose coronal curve was matched but thoracic kyphosis was different, were included in this study. The patients were divided into normal TK group and thoracic hypokyphosis group. EOS whole-body images were taken preoperatively and reconstructed by three-dimensional reconstruction. The whole spine anteroposterior X-ray was taken at 3 weeks after surgery. The radiographic parameters were measured on the preoperative and postoperative two-dimensional X-ray images: coronal Cobb angle, TK, lumbar lordosis (LL), pelvic incidence (PI) and pelvic tilt (PT). The vertebra rotation was obtained on the EOS three-dimensional reconstructed image, and the average vertebral rotation of the major thoracic curve (MTR), the average vertebral rotation of the proximal thoracic curve (PTR) and the average vertebral rotation of the lumbar curve (LR) were calculated. The paired sample t test was used to compare the difference of preoperative and postoperative radiographic parameters between the groups. Results: A total of 24 patients (12 pairs) were included in this study with an average age of (13.7±2.9) years. The preoperative Cobb angle was similar in the two groups (53.8°±10.2° vs 51.0°±11.1°, t=0.27, P=0.81). The average preoperative TK of the normal TK groups was 28.2°±6.1°, while that of the thoracic hypokyphosis group was 11.2°±5.6°(t=7.68, P<0.01). The MTR in the normal TK group was significantly smaller than that in the thoracic hypokyphosis group (10.2° vs 12.7°, t=-3.74, P<0.01), and there was a significant correlation between TK and MTR (r=0.30, P=0.03). As for the lumbar curve rotation, the LR of the normal TK group was significantly smaller than that in the thoracic hypokyphosis group (t=-2.65, P=0.002), but the absolute value of the two groups was similar (t=-0.33, P=0.31). The lumbar Cobb angle correction rate was significantly greater in patients with thoracic and lumbar curve rotating in the same direction than that in the opposite direction (81.1% vs 61.9%, t=4.24, P=0.005). Conclusions: It indicated that when the coronal deformity is matched, the MTR of the patients with thoracic hypokyphosis is significantly larger than that in the patients with normal thoracic kyphosis. The direction of the thoracic and lumbar curve rotation is required to be well concerned in the preoperative surgical planning.

[Clinical value of spectral CT imaging in preoperative evaluation of pathological grading of esophageal squamous cell carcinoma].

Objective: To investigate the value of spectral computed tomography quantitative parameters in the assessment of pathological grade of esophageal squamous cell carcinoma before operation. Methods: The imaging findings of 52 patients with confirmed esophageal squamous cell carcinoma by surgery and pathology were prospectively analyzed in Henan Provincial People's Hospital from June 2016 to May 2017.There were 43 males and 9 females, aged 49-76 years, with an average age of (66±8) years.All the patients were divided into three groups based on the pathological finding: well-differentiated group (n=12), moderately-differentiated group (n=20), poorly-differentiated group (n=20). All the patients received chest plain scan and double phase enhanced scan of gemstone spectral computed tomography.The enhancement attenuation (HU), the average of the slope of the spectral Hounsfield Unit curve (λ(HU)), normalized iodine concentration (NIC), normalized effective atomic number (Z(eff-a)) were measured and calculated.The difference in HU, λ(HU), NIC, Z(eff-a) among different grades were statistically analyzed.The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic efficiency of single and combined parameters in the differentiation of poorly-differentiated and well-moderately differentiated esophageal squamous cell carcinoma. Results: There were significant differences in HU, λ(HU), NIC, Z(eff-a) among different pathological grading of the esophageal squamous cell carcinoma in arterial phase and venous phase (F=4.496-9.056, H=23.204, 20.724, all P<0.05). The best single parameter to differentiate poorly-differentiated from well-moderately differentiated esophageal squamous cell carcinoma was NIC in arterial phase with areas under the ROC curve (AUC), the cutoff value, sensitivity, specificity, accuracy of 0.860, 0.197, 65.0%, 96.9%, 84.6%, respectively; the best combination of parameters was HU+ NIC+ λ(HU) in arterial phase with AUC, the threshold of predicted probability, sensitivity, specificity, accuracy of 0.913, 0.380, 85.0%, 81.3%, 82.7%, respectively. Conclusion: Gemstone spectral imaging quantitative parameters can be used to evaluate the pathological grading of esophageal squamous cell carcinoma, the NIC and HU+ NIC+ λ(HU) in arterial phase have the highest differential diagnostic efficiency.

A serum-circulating long noncoding RNA signature can discriminate between patients with clear cell renal cell carcinoma and healthy controls.

Serum biomarkers have not been fully incorporated into clinical use for the diagnosis of renal cell carcinoma (RCC). The recent discovery of long noncoding RNAs (lncRNAs), which have been reported in a variety of cancer types, suggested a promising new class of biomarkers for tumour diagnosis. The aim of our study was to evaluate whether the levels of circulating lncRNAs could be used as a tumour marker to discriminate between clear cell RCC (ccRCC) patients and healthy controls. Serum samples were collected from 71 ccRCC patients including 62 age- and sex-matched healthy controls and 8 patients with benign renal tumours. Eighty-two cancer-associated lncRNAs were assessed by reverse transcription and quantitative polymerase chain reaction in paired tissues and serum. A 5-lncRNA signature, including lncRNA-LET, PVT1, PANDAR, PTENP1 and linc00963, were identified and validated in the training set and testing set, respectively. The receiver operating characteristic curves for this serum 5-lncRNA signature were 0.900 and 0.823 for the two sets of serum samples. Moreover, five-minus-one lncRNA signatures demonstrated that none of the lncRNAs had a higher area under the curve than the others in either set. A risk model for the serum 5-lncRNA signature also determined that benign renal tumours can be distinguished from ccRCC samples. This work may facilitate the detection of ccRCC and serve as the basis for further studies of the clinical value of serum lncRNAs in maintaining surveillance and forecasting prognosis.

Minimally invasive approaches to treating chemosis of the eyes from unusual dural arteriovenous fistulae.

Chemosis of the eyes is usually attributed to carotid cavernous sinus dural arteriovenous fistulae. Herein, we reviewed unusual cases in which chemosis of the eyes originated from dural ateriovenous fistulae (dAVFs) that were distinctly different from carotid cavernous sinus fistulae. Cases in which ocular symptoms were related to increased intracranial pressure either due to sinus thrombosis or cortical venous drainage without involvement of superior or inferior ophthalmic veins were excluded in this review. Several different types of dural AVFs were associated with chemosis, and these included dAVFs harboring a feeding artery from branches of the external carotid artery directly draining to the superior ophthalmic vein or cavernous sinus via the superior petrous sinus, posterior fossa dAVFs draining via the inferior petrous sinus and cavernous sinus to the ophthalmic vein, a fistula between the ophthalmic artery or branches of the internal carotid artery and inferior ophthalmic vein, or tentorial fistula with a drainage vein to the cavernous sinus via the vein of Galen. This study reviews the symptomatology, treatment options, and cerebrovascular abnormalities observed for these unusual dAVF's with chemosis.

A pterion keyhole approach for the treatment of anterior circulation aneurysms.

The supraorbital keyhole approach is most frequently used in treatment for lesions within the anterior cranial base. However, it has some drawbacks, including cosmetically poor appearance of the scar, forehead deformity, and difficulty in dealing with some kinds of middle cerebral artery (MCA) and internal carotid artery (ICA) aneurysms. Therefore, we have developed a small pterion keyhole approach for an alternative access to treat anterior circulation aneurysms. An oblique skin incision about 3-5 cm in length was made just from 1.0 cm anterior to the superficial temporal artery at the level of the zygomatic arch, curved just below the temporal line to the forehead, and stopped at the hairline over the sylvian fissure. Then a small craniotomy (2-3 cm) was made just over the sylvian fissure and the aneurysms were exposed through the lateral cerebral fissure. We used this approach to treat 40 patients with aneurysms located in posterior communicating arteries (n=14), the MCA (n=10), the anterior communicating arteries (n=9), the anterior cerebral artery (n=1), the ophthalmic arteries (n=3), and the ICA (n=3). The general outcome of all patients was good without serious complications from the surgical technique even though 3 cases underwent intraoperative premature rupture of the aneurysms. No approach-related complication occurred except that one patient had vasospasm 2 days after the aneurysm clipping. In conclusion, this pterion keyhole approach can achieve the best operative effect for the treatment of intracranial anterior circulation aneurysms in a selective group of patients with several advantages over traditional craniotomy including minor tissue damage, less brain retraction, a superior cosmetic result, and shorter duration of surgery. Moreover, the operative field becomes wider in the deep area, providing sufficient space for microscope-assisted surgery without the need for highly specialized instruments.

Botulinum toxin treatment for acute traumatic complete sixth nerve palsy.

AIMS: To investigate the benefits of botulinum toxin (BTX) injection for acute unilateral complete sixth nerve palsy caused by trauma. METHODS: We retrospectively reviewed patients treated for acute unilateral complete sixth nerve palsy caused by head injury during a 10-year period (between March 1993 and February 2003) in our hospital. The BTX treatment group was defined as patients who received BTX injection within 3 months of injury. Patients who presented within 3 months of trauma, and had no previous BTX injection or surgery were enrolled as the conservative treatment group. Comparison of the patient demographics, palsy characteristics, angle of deviations, and recovery rates were made between the two groups. RESULTS: In all, 33 patients were enrolled by our inclusion criteria. Of these, 19 patients were treated conservatively, and 14 patients were treated with BTX. A total of 79% of our patients presented with abduction deficit of grade -5. The results showed that there was no significant difference in the outcome for the two groups based on age, gender, time to presentation, severity, and initial angle of deviation. The BTX group had a higher recovery rate than the conservative treatment group (64.3 vs 26.3%, P=0.028). Among 26 patients with grade -5 abduction deficit, the recovery rate was higher in the BTX-treated patients than in the conservatively treated patients, which had no statistical significance (50 vs 18.8%, P=0.09). CONCLUSION: BTX facilitates recovery of acute traumatic complete sixth nerve palsy in severely injured patients.

Neuroendocrine differentiation in sporadic CRC and hereditary nonpolyosis colorectal cancer.

Extent neuroendocrine differentiation can be encountered in many human neoplasm derived from different organs and systems using immunohistochemistry and ultrastructural techniques. The tumor cells' behaviors resemble those of neurons and neuroendocrine cells. The presence of neuroendocrine differentiation reputedly appears to be associated with a poorer prognosis than the adenocarcinoma counterparts in sporadic human neoplasm. In this review the neuroendocrine carcinoma and the adenocarcinoma with neuroendocrine differentiation of colon and rectum both in sporadic colorectal carcinoma and the hereditary nonpolyposis colorectal cancer, the relationship of neuroendocrine differentiation and some possible molecular pathways in tumorogenesis of colorectal cancer will be discussed. Possible treatment strategy will also be addressed.

Characterization of the distinct orthotopic bone-forming activity of 14 BMPs using recombinant adenovirus-mediated gene delivery.

Efficacious bone regeneration could revolutionize the clinical management of bone and musculoskeletal disorders. Although several bone morphogenetic proteins (BMPs) (mostly BMP-2 and BMP-7) have been shown to induce bone formation, it is unclear whether the currently used BMPs represent the most osteogenic ones. Until recently, comprehensive analysis of osteogenic activity of all BMPs has been hampered by the fact that recombinant proteins are either not biologically active or not available for all BMPs. In this study, we used recombinant adenoviruses expressing the 14 types of BMPs (AdBMPs), and demonstrated that, in addition to currently used BMP-2 and BMP-7, BMP-6 and BMP-9 effectively induced orthotopic ossification when either AdBMP-transduced osteoblast progenitors or the viral vectors were injected into the quadriceps of athymic mice. Radiographic and histological evaluation demonstrated that BMP-6 and BMP-9 induced the most robust and mature ossification at multiple time points. BMP-3, a negative regulator of bone formation, was shown to effectively inhibit orthotopic ossification induced by BMP-2, BMP-6, and BMP-7. However, BMP-3 exerted no inhibitory effect on BMP-9-induced bone formation, suggesting that BMP-9 may transduce osteogenic signaling differently. Our findings suggest that BMP-6 and BMP-9 may represent more effective osteogenic factors for bone regeneration.