Oxytocin neurons enable social transmission of maternal behaviour.

Maternal care, including by non-biological parents, is important for offspring survival1-8. Oxytocin1,2,9-15, which is released by the hypothalamic paraventricular nucleus (PVN), is a critical maternal hormone. In mice, oxytocin enables neuroplasticity in the auditory cortex for maternal recognition of pup distress15. However, it is unclear how initial parental experience promotes hypothalamic signalling and cortical plasticity for reliable maternal care. Here we continuously monitored the behaviour of female virgin mice co-housed with an experienced mother and litter. This documentary approach was synchronized with neural recordings from the virgin PVN, including oxytocin neurons. These cells were activated as virgins were enlisted in maternal care by experienced mothers, who shepherded virgins into the nest and demonstrated pup retrieval. Virgins visually observed maternal retrieval, which activated PVN oxytocin neurons and promoted alloparenting. Thus rodents can acquire maternal behaviour by social transmission, providing a mechanism for adapting the brains of adult caregivers to infant needs via endogenous oxytocin.

Pediatric Eosinophilia: A Review and Multiyear Investigation into Etiologies.

OBJECTIVES: To identify the etiology of peripheral eosinophilia in a large pediatric population and to develop a diagnostic algorithm to help guide diagnosis and management of peripheral eosinophilia in the outpatient pediatric population. STUDY DESIGN: We performed a retrospective chart review of children presenting to Texas Children's Hospital in Houston with peripheral eosinophilia between January 1, 2011 and December 31, 2019. Eosinophilia was classified as mild (absolute eosinophil count [AEC] >500 and <1500 cells/µL), moderate (AEC >1500 and <4500 cells/µL), or severe (AEC >4500 cells/µL). Demographic information and diagnostic workup data were collected. RESULTS: A total of 771 patients aged <18 years were evaluated. The most common cause of eosinophilia was allergy (n = 357; 46%), with atopy (n = 296) and drug reaction (n = 54) the most common subcauses. This was followed by unknown etiology (n = 274; 36%), infectious causes (n = 72; 9%), and eosinophilic disorders (n = 47; 6%). Many patients with an unknown cause (n = 202; 74%) had limited or no follow-up testing. CONCLUSIONS: More information on the etiology of pediatric eosinophilia and workup data could help identify the causes. This study provides important information on the evaluation of eosinophilia in the US pediatric population, including a diagnostic algorithm to guide primary care pediatricians.

Homeostatic circuits selectively gate food cue responses in insular cortex.

Physiological needs bias perception and attention to relevant sensory cues. This process is 'hijacked' by drug addiction, causing cue-induced cravings and relapse. Similarly, its dysregulation contributes to failed diets, obesity, and eating disorders. Neuroimaging studies in humans have implicated insular cortex in these phenomena. However, it remains unclear how 'cognitive' cortical representations of motivationally relevant cues are biased by subcortical circuits that drive specific motivational states. Here we develop a microprism-based cellular imaging approach to monitor visual cue responses in the insular cortex of behaving mice across hunger states. Insular cortex neurons demonstrate food-cue-biased responses that are abolished during satiety. Unexpectedly, while multiple satiety-related visceral signals converge in insular cortex, chemogenetic activation of hypothalamic 'hunger neurons' (expressing agouti-related peptide (AgRP)) bypasses these signals to restore hunger-like response patterns in insular cortex. Circuit mapping and pathway-specific manipulations uncover a pathway from AgRP neurons to insular cortex via the paraventricular thalamus and basolateral amygdala. These results reveal a neural basis for state-specific biased processing of motivationally relevant cues.

High dose rate endoluminal brachytherapy in the treatment of endobronchial lesions - experience of a single institution and literature review.

PURPOSE: To evaluate the efficacy and toxicity of Iridium-192 high-dose-rate endobronchial brachytherapy (HDR-EBT) for palliation of symptoms and for curative intent. MATERIAL AND METHODS: This is a retrospective study of a prospectively registered cohort of 31 patients with endobronchial lesions treated with HDR-EBT at our institution between 2008 and 2020. Eighteen patients were treated with palliative intent and 13 curative intent; 4 of them as a boost to external radiation therapy (XRT). The primary objectives of the study were to analyze the symptomatic relief, endoscopic response, and treatment-related toxicity. As a secondary endpoint, survival analyses were performed. RESULTS: In palliative setting, most of the symptomatic patients (80%) presented a significant clinical improvement and 75% presented endoscopic improvement of the lesions. In curative setting, all patients with visible lesions had endoscopic improvement and better survival than palliatively treated patients (median: 78 and 9 months, respectively; p = 0.002). There were no complications in 91.4% of the treatments: only one pneumonia, one pneumothorax and one bronchial stenosis occurred, all in palliative treatments. No fatal hemoptysis happened. Acute toxicity was mild (G ≤ 2) and transitory. DISCUSSION: HDR-EBT is an excellent, safe, and inexpensive palliative treatment of symptoms caused by endobronchial growth of tumors in the proximal airway, either as a single treatment or in combination with XRT. It can also be an alternative in the treatment of initial malignant tumors when surgery or XRT is not possible, and it may also play a role in treating non-malignant bronchial obstructions.

Prevertebral cervical approach to posterior mediastinum parathyroid adenomas.

BACKGROUND: About 4 years ago, we described the pure endoscopic cervical approach to posterior mediastinum parathyroid adenomas, which we called the "prevertebral cervical approach". At that time, we had operated on three patients and did not have enough quality videos to demonstrate this approach. After broadening our experience, we present our results and show this technique through a video. METHODS: From June 2015 to January 2021, information on patients undergoing the prevertebral cervical approach was obtained from a specific prospective database, including clinical presentation, biochemistry, preoperative imaging, surgical approach and patient outcomes. The step by step technique is described for both right- and left-sided adenomas, by means of a short video clip. RESULTS: Ten patients were operated on using this technique. Seven adenomas were right-sided and three were left-sided. The mean surgical time was 33 ± 7 min. There were neither intraoperative nor major postoperative complications. Seven patients presented with a slight subcutaneous emphysema, which did not cause complaints. All patients were discharged the day after surgery, except for one patient with a previous open neck removal of four glands due to secondary hyperparathyroidism, which required calcium replacement. Calcium and parathyroid hormone levels were normalised in the other nine patients after surgery. One patient experienced a transient recurrent laryngeal nerve injury which was spontaneously resolved within 1 month. No permanent recurrent laryngeal nerve injury was found. The postoperative cosmetic outcomes were excellent. CONCLUSION: In our experience, the pure cervical endoscopic approach has shown a high feasibility and short operation time, with excellent postoperative results regarding patient comfort, length of stay and disease cure. This approach also offers a very reasonable procedure cost, and may result in a less aggressive surgical option when compared with thoracic approaches.

The anconeus muscle revisited: double innervation pattern and its clinical implications.

PURPOSE: The aim of the present study is to describe in detail the morphology and innervation pattern of the anconeus muscle, bearing in mind clinical implications such as iatrogenic injuries during surgical elbow approaches. METHODS: A cadaveric study was performed; 56 elbows from 28 formalin-fixed cadavers belonging to the Anatomy Department of Universidad Complutense of Madrid were dissected. The triceps-anconeus nerve was located and dissected. A second innervation to the anconeus muscle from a branch of the posterior interosseous nerve (PIN) was occasionally detected. Taking the lateral epicondyle as a landmark, the entry points of both nerves in the muscle were referenced, the triceps-anconeus nerve was referenced at 0°, 30°, 45°, 70° and 90° of elbow flexion, and the PIN branch at 0°. RESULTS: Anconeus muscle was present in all specimens. The triceps-anconeus nerve was present in all of the dissected elbows. A branch from PIN to the anconeus muscle was present in 38 of the 54 elbows (70.4%). There were statistically significant differences in all measurements regarding the specimens' gender, being higher for men. CONCLUSIONS: There is evidence of a high frequency of a double innervation pattern for the anconeus muscle: the main branch of triceps-anconeus muscle depending on the radial nerve, which is liable to being damaged during posterior elbow approaches, and a secondary branch depending on the PIN. There are very few references to this finding in Anatomical literature and none with such a large sample size.

High-dose neoadjuvant chemoradiotherapy versus chemotherapy alone followed by surgery in potentially-resectable stage IIIA-N2 NSCLC. A multi-institutional retrospective study by the Oncologic Group for the Study of Lung Cancer (Spanish Radiation Oncology Society).

BACKGROUND: The optimal induction treatment in potentially-resectable stage IIIA-N2 NSCLC remains undefined. AIM: To compare neoadjuvant high-dose chemoradiotherapy (CRT) to neoadjuvant chemotherapy (CHT) in patients with resectable, stage IIIA-N2 non-small-cell lung cancer (NSCLC). METHODS: Retrospective, multicentre study of 99 patients diagnosed with stage cT1-T3N2M0 NSCLC who underwent neoadjuvant treatment (high-dose CRT or CHT) followed by surgery between January 2005 and December 2014. RESULTS: 47 patients (47.5%) underwent CRT and 52 (52.5%) CHT, with a median follow-up of 41 months. Surgery consisted of lobectomy (87.2% and 82.7%, in the CRT and CHT groups, respectively) or pneumonectomy (12.8% vs. 17.3%). Nodal downstaging (to N1/N0) and Pathologic complete response (pCR; pT0pN0) rates were significantly higher in the CRT group (89.4% vs. 57.7% and 46.8% vs. 7.7%, respectively; p < 0.001)). Locoregional recurrence was significantly lower in the CRT group (8.5% vs. 13.5%; p = 0.047) but distant recurrence rates were similar in the two groups. Median PFS was 45 months (CHT) vs. "not reached" (CRT). Median OS was similar: 61 vs. 56 months (p = 0.803). No differences in grade ≥3 toxicity were observed. On the Cox regression analysis, advanced pT stage was associated with worse OS and PFS (p < 0.001) and persistent N2 disease (p = 0.002) was associated with worse PFS. CONCLUSIONS: Compared to neoadjuvant chemotherapy alone, a higher proportion of patients treated with preoperative CRT achieved nodal downstaging and pCR with better locoregional control. However, there were no differences in survival. More studies are needed to know the optimal treatment of these patients.

Management of Chronic Hepatitis C in End-stage Renal Disease.

Treatment for chronic viral hepatitis C has advanced dramatically to current standard of care all-oral direct-acting antiviral regimens with relatively short treatment duration and high efficacy. Patients with comorbid end-stage renal disease have constituted a "special patient population" with data and treatment options lagging behind that of the broader population of patients with chronic hepatitis C until recently. Herein we review the current evidence base for direct-acting antiviral therapy in this population. We provide a suggested algorithm for the evaluation of such patients for therapy. We highlight special considerations in regards to the choice of regimen, duration, and timing in regards to potential kidney transplantation.

Arthroscopic Subtalar Arthrodesis: Does the Type of Fixation Modify Outcomes?

The goal of the present study was to analyze a modified American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale score, time to union, and the incidence of fusion after isolated arthroscopic posterior subtalar arthrodesis using either 1 or 2 screws of different diameters. We reviewed a consecutive series of 65 patients, mean age 50.0 ± 15.6 years, including 38 males (58.5%) and 27 females (41.5%), who had undergone arthrodesis from May 2004 to February 2011. The mean follow-up duration was 57.5 (range 24 to 105) months. The patients were divided into 3 groups according to the fixation method used: group 1 (n = 12; 18.5%) underwent fixation with one 6.5-mm screw; group 2 (n = 40; 61.5%) with one 7.3-mm screw; and group 3 (n = 13; 20%) with two 7.3-mm screws. An overall statistically significant (p <.0001) improvement was seen in the modified AOFAS scale score for all 3 fixation groups; however, the difference was not statistically significant (p = .79) among the fixation groups. Fusion was achieved in 62 patients (95.4%) after a mean of 12.1 (range 9 to 16) weeks. The difference in the time to union was not statistically significant (p = .781) among the fixation groups. Nine patients (13.8%) experienced complications, and nonunion was significantly (p = .005) more prevalent in the single 6.5-mm screw group. In conclusion, all 3 screw configurations led to improved modified AOFAS scale scores, although nonunion was more common among patients fixed with a single 6.5-mm screw.

Prevertebral cervical approach: a pure endoscopic surgical technique for posterior mediastinum parathyroid adenomas.

BACKGROUND: Parathyroid gland mediastinal ectopia is an unusual but challenging condition in surgical management of hyperparathyroidism. Posterior mediastinum parathyroid ectopia is rare, and glands need to be removed either with a broad open cervical or thoracic approach. In recent years, several minimally invasive approaches to mediastinal parathyroid glands have been described, but for posterior mediastinum adenomas, proposed techniques are transthoracic. METHODS: The aim of this paper is to describe, to our best knowledge for the first time, a standardized pure endoscopic cervical technique to approach posterior mediastinal parathyroid adenomas which we have used in three patients. RESULTS: The technique was applied in three patients which excellent surgical, postoperative, and cosmetic results. CONCLUSIONS: Endoscopic prevertebral approach is a feasible, sure and inexpensive standardized pure endoscopic cervical approach to posterior mediastinal parathyroid adenomas, which may result in a less aggressive surgical option when compared with thoracic approaches.

Building Bridges to Address Health Disparities in Puerto Rico: the "Salud para Piñones" Project.

Over the past several decades, Puerto Ricans have faced increased health threats from chronic diseases, particularly diabetes and hypertension. The patient-provider relationship is the main platform for individual disease management, whereas the community, as an agent of change for the community's health status, has been limited in its support of individual health. Likewise, traditional research approaches within communities have placed academic researchers at the center of the process, considering their knowledge was of greater value than that of the community. In this paradigm, the academic researcher frequently owns and controls the research process. The primary aim is contributing to the scientific knowledge, but not necessarily to improve the community's health status or empower communities for social change. In contrast, the community-based participatory research (CBPR) model brings community members and leaders together with researchers in a process that supports mutual learning and empowers the community to take a leadership role in its own health and well-being. This article describes the development of the community-campus partnership between the University of Puerto Rico School of Medicine and Piñones, a semi-rural community, and the resulting CBPR project: "Salud para Piñones". This project represents a collaborative effort to understand and address the community's health needs and health disparities based on the community's participation as keystone of the process. This participatory approach represents a valuable ally in the development of long-term community-academy partnerships, thus providing opportunities to establish relevant and effective ways to translate evidence-based interventions into concrete actions that impact the individual and community's wellbeing.

Subtalar arthroscopic arthrodesis: Technique and outcomes.

PURPOSE: The goal of this study was to describe the surgical technique and our results with arthroscopic posterior subtalar arthrodesis. MATERIAL AND METHODS: Retrospective case series of 65 patients (38 men and 27 women) averaging 50 years of age (range 21-72 years) undergoing posterior arthroscopic subtalar arthrodesis using one or two percutaneous 6.5-7.3mm screws between May 2004 and February 2011, with a mean follow-up of 57.5 months (range 24-105 months). RESULTS: We achieved a 95.4% union rate after an average of 12.1 weeks (range 9 to 16 weeks). 12.3% of patients suffered complications, including superficial infection, nonunion and need for hardware removal. The AOFAS score improved from 51.5 points (19-61 points) preoperatively to 81.9 points (60-94 points) in the postoperative period. CONCLUSIONS: We describe the surgical technique for arthroscopic subtalar arthrodesis, which as proven to be a safe and reliable technique in our experience, with consistent improvements in AOFAS scores.

Arthrodesis of the thumb carpometacarpal joint using a quadrangular plate: surgical technique and long-term results of 70 patients.

PURPOSE: To assess the long-term results of trapeziometacarpal arthrodesis using a quadrangular plate, regarding clinical, radiological and functional outcomes, as well as development of complications. MATERIAL AND METHOD: From 2005 to 2015, 70 patients were treated at our institution for primary osteoarthrosis of thumb carpometacarpal joint performing a trapeziometacarpal arthrodesis. A total of 85 arthrodesis were carried out using a titanium quadrangular plate (Proflyle plate, Stryker®, Kalamazoo MI, USA), without grafting in any case. Pre- and postoperative functional data were assessed at the outpatient clinics using DASH, MWS and VAS. All patients were asked for their ability to perform basic daily activities before and after surgery. All patients were also asked about satisfaction and their return to their jobs after surgery. Pre- and postoperative radiological data were also assessed. RESULTS: There were 59 females and 11 males with an average age of 55 years (range 44-60). In 66 cases arthrodesis was carried out in the dominant hand, in 45 cases the right thumb was involved, and in 40 the left thumb was involved; in 15 cases arthrodesis was carried out bilaterally. Preoperative average DASH score was 64 (range 50-85), postoperative average score was 25 (range 5-61). Regarding MWS, 51 patients obtained excellent results, 15 patients obtained good results and 4 patients referred poor results. The preoperative average score of VAS was 6 (range 5-10), which decrease to an average of 2 (range 0-3) after surgery; all those differences were statistically significant. All patients reported a mild loss of motion; however, all of them reported improvement to carry out daily activities. There were four cases of nonunion because of failure of fixation and two cases with dysesthetic scar. There was no development of osteoarthritis in adjacent joints. The average follow-up was 60 months. CONCLUSIONS: The use of quadrangular plates for arthrodesis of the trapeziometacarpal joint is a safety and reproducible technique with a low rate of complications. Arthrodesis decreases pain and improves function in patients with primary osteoarthritis of the thumb carpometacarpal joint; in spite of a mild loss of motion, patients are satisfied with this procedure.

Analysis of complications after a floating elbow injury.

BACKGROUND: The aim of the present study is to analyse complications after a floating elbow injury, attempting to establish which of them act as a poor prognosis factor regarding clinical and functional results. MATERIALS AND METHODS: Twenty-three patients who suffered a floating elbow injury, treated at our institution from 2004 to 2013, were retrospectively reviewed. Patients were divided into four groups depending on the type of injury. An analysis of demographic data, associated injuries, treatment options and complications was carried out. Clinical evaluation was made by a conventional goniometer, testing flexo-extension and prono-supination ranges. For functional evaluation, the Mayo Elbow Performance Score was employed. Association between radioulnar synostosis, articular surface disruption, nerve injury and clinical and functional results was analysed. RESULTS: Patients with radioulnar synostosis had worse results in functional evaluation than patients without it (56.6 vs. 75); this difference was statistically significant (p = 0.05). Regarding intra-articular extension, we found statistical association with worse results in functional evaluation (p = 0.018); however, nerve palsy does not seem to influence functional results. CONCLUSIONS: Radioulnar synostosis and intra-articular extension of the injury are poor prognosis factor in floating elbow.

A new genotype of bovine leukemia virus in South America identified by NGS-based whole genome sequencing and molecular evolutionary genetic analysis.

BACKGROUND: Bovine leukemia virus (BLV) is a member of retroviridae family, together with human T cell leukemia virus types 1 and 2 (HTLV-1 and -2) belonging to the genes deltaretrovirus, and infects cattle worldwide. Previous studies have classified the env sequences of BLV provirus from different geographic locations into eight genetic groups. To investigate the genetic variability of BLV in South America, we performed phylogenetic analyses of whole genome and partial env gp51 sequences of BLV strains isolated from Peru, Paraguay and Bolivia, for which no the molecular characteristics of BLV have previously been published, and discovered a novel BLV genotype, genotype-9, in Bolivia. RESULTS: In Peru and Paraguay, 42.3 % (139/328) and over 50 % (76/139) of samples, respectively, were BLV positive. In Bolivia, the BLV infection rate was up to 30 % (156/507) at the individual level. In Argentina, 325/420 samples were BLV positive, with a BLV prevalence of 77.4 % at the individual level and up to 90.9 % at herd level. By contrast, relatively few BLV positive samples were detected in Chile, with a maximum of 29.1 % BLV infection at the individual level. We performed phylogenetic analyses using two different approaches, maximum likelihood (ML) tree and Bayesian inference, using 35 distinct partial env gp51 sequences from BLV strains isolated from Peru, Paraguay, and Bolivia, and 74 known BLV strains, representing eight different BLV genotypes from various geographical locations worldwide. The results indicated that Peruvian and Paraguayan BLV strains were grouped into genotypes-1, -2, and -6, while those from Bolivia were clustered into genotypes-1, -2, and -6, and a new genotype, genotype-9. Interestingly, these results were confirmed using ML phylogenetic analysis of whole genome sequences obtained by next generation sequencing of 25 BLV strains, assigned to four different genotypes (genotypes-1, -2, -6, and -9) from Peru, Paraguay, and Bolivia. Comparative analyses of complete genome sequences clearly showed some specific substitutions, in both structural and non-structural BLV genes, distinguishing the novel genotype-9 from known genotypes. CONCLUSIONS: Our results demonstrate widespread BLV infection in South American cattle and the existence of a new BLV genotype-9 in Bolivia. We conclude that at least seven BLV genotypes (genotypes-1, -2, -4, -5, -6, -7, and -9) are circulating in South America.

Gliofibroma: Report of Four Cases and Review of the Literature.

Gliofibroma is a relatively rare variant of a mixed glial-fibrous tumor more frequent in children than in adults. It has been reported to appear all along the neuraxis, with predilection for the midline. Its evolution is usually benign, although few examples have shown either multiple sites of involvement or leptomeningeal dissemination. Some authors regard it as part of the desmoplastic astrocytoma spectrum. We report here four examples of this rare condition which exemplify its histological patterns and biological behavior, and provide a review of the literature. Even though this tumor is commonly regarded as heterogeneous and with variable course, our literature review points to a set of clinical and pathological traits that are constant, such as age, location and gross and histological characteristics, as well as a predictable evolution. Currently, this tumor is not included in the WHO Classification of CNS tumors.

The role of tridimensional dynamic ultrasound for pelvic floor evaluation.

INTRODUCTION: Dynamic endoanal ultrasound has emerged in recent years as a test that could replace the now existing tests in the diagnosis of pelvic floor disorders. The aim of this paper is to determine the usefulness of echodefecography in the diagnosis and evaluation of patients with symptoms of anorrectal obstruction, and show the results obtained after its implementation in a pelvic floor unit, as a complementary tool that could replace conventional defecography. METHODS: In this retrospective study we analyzed 66 patients with a mean age of 55 years (19-83), 61 women (92%). All dynamic ultrasound was performed in 3 dimensions and was correlated with symptoms and physical findings in the consultation. A descriptive and inferential study was performed to find a kappa correlation between physical examination and echodefecography. RESULTS: The reasons for consultation were: Anorrectal obstruction syndrome 36 patients (54.5%), pelvic organ prolapse 27 patients (40.9%), and anorrectal obstruction syndrome along with pelvic organ prolapse 3 patients (4.5%). The correlation of the 2 groups indicated that echodefecography diagnosed more patients with grade III rectocele, enteroceles, and anismus than the combination of scan-ultrasound-manometry-proctoscopy (Kappa 0.26, 0.38 and 0.21, 95% CI: from 0,07 to 1.00, 0.15 to 1.00 and from 0.12 to 1.00, respectively) (P<.001). Conversely, echodefecography diagnosed less perineal descense (Kappa 0.28, 95% CI: 0.12 to 1.00). CONCLUSIONS: Dynamic anal ultrasonography may have a role as a complementary test in patients with pelvic floor disorders, achieving diagnoses that would go undetected by inspection, physical examination and manometry.

Enriched mesoporous bioactive glass scaffolds as bone substitutes in critical diaphyseal bone defects in rabbits.

In the field of orthopedic surgery, there is an increasing need for the development of bone replacement materials for the treatment of bone defects. One of the main focuses of biomaterials engineering are advanced bioceramics like mesoporous bioactive glasses (MBG´s). The present study compared the new bone formation after 12 weeks of implantation of MBG scaffolds with composition 82,5SiO2-10CaO-5P2O5-x 2.5SrO alone (MBGA), enriched with osteostatin, an osteoinductive peptide, (MBGO) or enriched with bone marrow aspirate (MBGB) in a long bone critical defect in radius bone of adult New Zealand rabbits. New bone formation from the MBG scaffold groups was compared to the gold standard defect filled with iliac crest autograft and to the unfilled defect. Radiographic follow-up was performed at 2, 6, and 12 weeks, and microCT and histologic examination were performed at 12 weeks. X-Ray study showed the highest bone formation scores in the group with the defect filled with autograft, followed by the MBGB group, in addition, the microCT study showed that bone within defect scores (BV/TV) were higher in the MBGO group. This difference could be explained by the higher density of newly formed bone in the osteostatin enriched MBG scaffold group. Therefore, MBG scaffold alone and enriched with osteostatin or bone marrow aspirate increase bone formation compared to defect unfilled, being higher in the osteostatin group. The present results showed the potential to treat critical bone defects by combining MBGs with osteogenic peptides such as osteostatin, with good prospects for translation into clinical practice. STATEMENT OF SIGNIFICANCE: Treatment of bone defects without the capacity for self-repair is a global problem in the field of Orthopedic Surgery, as evidenced by the fact that in the U.S alone it affects approximately 100,000 patients per year. The gold standard of treatment in these cases is the autograft, but its use has limitations both in the amount of graft to be obtained and in the morbidity produced in the donor site. In the field of materials engineering, there is a growing interest in the development of a bone substitute equivalent. Mesoporous bioactive glass (MBG´s) scaffolds with three-dimensional architecture have shown great potential for use as a bone substitutes. The osteostatin-enriched Sr-MBG used in this long bone defect in rabbit radius bone in vivo study showed an increase in bone formation close to autograft, which makes us think that it may be an option to consider as bone substitute.

In vivo behavior in rabbit radius bone defect of scaffolds based on nanocarbonate hydroxyapatite.

Bone defects treatment may require the use of biomaterials that behave as a support and promote bone regeneration. Limitations associated with the use of autografts and allografts make it necessary to design new synthetic bone substitutes. Some of the most promising biomaterials currently under investigation are based on nanocarbonate hydroxyapatite (nCHA). In this study, we studied the bone-inducing capacity of nCHA-based scaffolds alone (SAG) and enriched with osteostatin (SAGO) or with bone marrow aspirate(SAGB) after implantation for 12 weeks in a 15-mm long critical defect performed in the radius of New Zealand rabbits. Bone formation obtained was compared with a group with the unfilled defect (CE), as control group, and other with the defect filed with iliac crest autograft (GS), as gold standard. X-ray follow-up was performed at 2, 4, 6 and 12 weeks and µCT and histological studies at 12 weeks. The radiological results showed a greater increment in bone formation in the GS group (75%-100%), followed by the SAG and SAGB groups (50%-75%). µCT results showed an increase of bone volume/tissue volume values in GS group followed by SAG and SAGB groups (0.53, 0.40, and 0.31 respectively) compared with CE group (0.26). Histological results showed limited resorption of the nCHA scaffolds and partial osseointegration in the SAG and SAGB groups. However, in the SAGO group, the presence of connective tissue encapsulating the scaffold was detected. In SAG, SAGB, and increase of bone formation were observed compared with CE group, but less than the GS group. Thus, the investigated materials represent a significant advance in the design of synthetic materials for bone grafting, but further studies are needed to bring their in vivo behavior closer to autograft, the gold standard.