IMMOBILIZATION OF MOUFLON (OVIS ORIENTALIS MUSIMON) USING MEDETOMIDINE-KETAMINE-MORPHINE OR DEXMEDETOMIDINE-KETAMINE-MORPHINE.

This study is aimed at evaluating the efficacy of two protocols for the immobilization of mouflon (Ovis orientalis musimon). Six mouflon were immobilized twice using IM medetomidine 0.07 ± 0.01 mg/kg, ketamine 2.88 ± 0.48 mg/kg, and morphine 0.57 ± 0.09 mg/kg (MKM) or dexmedetomidine 0.04 ± 0.01 mg/kg, ketamine 3.01 ± 0.6 mg/kg, and morphine 0.60 ± 0.12 mg/kg (DKM). Anesthetic times were recorded from injection to initial drug effects, sternal recumbency, lateral recumbency, unresponsiveness to external stimuli, and recovery following atipamezole IM administration. Cardiopulmonary variables (HR in beats/min, RR in breaths/min, mean, systolic, and diastolic noninvasive blood pressure [MAP, SAP, DAP] in mm Hg, oxygen hemoglobin saturation [SpO2)], expired end tidal carbon dioxide [PECO2]), and rectal temperature in °C were monitored and recorded. No statistically significant differences were detected between protocols at any time point and no significant differences were detected in any measured variables at any time point between protocols. However, a significant decrease in the noninvasive blood pressure variables (SAP, MAP, and DAP) and in the RR were detected over time. Both chemical immobilization protocols provided at least 50 min of immobilization in mouflon, allowing minor procedures and tracheal intubation.

Factor Xa Inhibition by Rivaroxaban Modified Mitochondrial-Associated Proteins in Human Abdominal Aortic Aneurysms.

BACKGROUND: The presence of intraluminal thrombus and mitochondrial dysfunction in human abdominal aortic aneurysms (AAAs) have been associated with aneurysmal growth and rupture. The objective of the study was to study if endogenous factor Xa (FXa) may modulate mitochondrial functionality and expression of proteins associated with mitophagy in human AAAs. METHODS: AAA sites with intraluminal thrombus were obtained from 6 patients undergoing elective AAA surgery repair. Control samples were collected from 6 organ donors. The effect of FXa was analyzed by in vitro incubation of AAA with 50 nmol/L rivaroxaban, an oral FXa inhibitor. RESULTS: The enzymatic activities of citrate synthase, a biomarker of mitochondrial density, and cytochrome C oxidase, a biomarker of mitochondrial respiratory chain functionality, were significantly reduced in the AAA sites with respect to the healthy aorta (citrate synthase activity in µU/min/µg protein: control: 3.51 ± 0.22 vs. AAA: 0.37 ± 0.15.; P < 0.01; cytochrome C oxidase activity in µOD/min/µg protein: control: 8.05 ± 1.57 vs. AAA: 3.29 ± 1.05; P < 0.05). The addition of rivaroxaban to AAA reverted the activity of both citrate synthase and cytochrome C oxidase to similar values to control. Mitochondrial Drp-1 expression was higher in AAA sites than in either control aortas or rivaroxaban-incubated AAA sites. Cytosolic content of Drp-1 phosphorylated at Ser637, mitochondrial Parkin, and mitochondrial PINK1-Parkin interaction were significantly reduced in the AAA sites with respect to control aortas. For all these parameters, rivaroxaban-incubated AAA showed similar values compared with control aortas. CONCLUSIONS: In human AAA, rivaroxaban improved mitochondrial functionality that was associated with changes in proteins related to mitophagy. Its opens possible new effects of endogenous FXa on the mitochondria in the human AAA site.

Effects of local application of alendronate on early healing of extraction socket in dogs.

OBJECTIVE: The aim of the present study was to assess the effects of alendronate (ALN) on bone remodeling following tooth extraction in a dog model. MATERIAL AND METHODS: For the study, fifteen male Beagles dogs of approximately 12 months of age were used. Mesial roots of four mandibular premolars were endodontically treated, and the distal roots were removed. ALN concentrations of 0.5, 1, and 2 mg/mL were topically applied for 15 min, while a sterile saline was used as a negative control. After the healing period of 1, 2, and 8 weeks, the samples were analyzed by micro-CT and histology. RESULTS: Treatment with ALN increased vertical distance between the lingual and the buccal crestal bones. While the ALN-treated sockets had preserved more lingual bone areas, control sockets showed better preservation of the buccal bone areas. ALN treatment resulted in more osteoid formation within the extraction sockets compared with the control. Higher bone volume was found in ALN groups than in the control at 2-week and 8-week healing periods, reaching the significant difference only for the extraction sockets pooled for the ALN treatment. CONCLUSIONS: Although ALN treatment could not prevent buccal bone resorption following tooth extraction in dogs, it proved beneficial for the preservation of the lingual bone and formation of new bone within the socket. There was no clear relation between the ALN dosages and the alterations within the extraction sockets. CLINICAL RELEVANCE: ALN affects bone remodeling of the extraction socket. The optimal concentration remains to be determined in future studies.

Rabbit as model for osteoporosis research.

Osteoporosis is a major public health problem affecting more than 200 million people worldwide. The use of different animal models, for the study of its pathophysiology and treatments, is important being actually the ovariectomized rat the most widely used; although this model has several problems due its small size, lack of true closure of epiphyseal plate and bone differences with humans. This review is aimed at summarizing the most common methods published for osteoporosis induction in rabbits as model for human disease with their advantages and disadvantages. The paper shows the advantages of the use of this specie compared with the rat. All the techniques seemed to achieve the osteoporotic condition, but the one which obtained the most consistent bone mineral reduction in less time was the combination of surgery and corticoid treatment. The conclusion of the review was that rabbits are promising as a model of osteoporosis research because of their size, haversian remodelling and closure of epiphyseal plate, which solve some of the problems of the rat model. There are different techniques in the literature used to achieve the osteoporotic condition with diverse results, but there is a lack of consensus as to the best one.

Evaluation of a new tricalcium phosphate for guided bone regeneration: an experimental study in the beagle dog.

This study compared the in vivo behavior of two biomaterials, xenograft (Bio-Oss®) and alloplastic tricalcium phosphate (Sil-Oss®), vs a control (no biomaterial) in beagle dogs treated with guided bone regeneration (GBR). Six male adult beagle dogs were included. The third and fourth mandibular premolars and first mandibular molars (3P3, 4P4 and 1M1) on both sides were extracted. After 12 weeks of healing, Straumann implants (3.3 × 8 mm) were placed, performing standardized defects (3.3 × 6 mm) in the vestibular aspect of the alveolar bone. The defects were surgically treated by randomized placement of xenograft (Bio-Oss®), alloplastic tricalcium phosphate (Sil-Oss®) or no biomaterial and covered with a resorbable collagen membrane (BioGide®). After an additional 12-week healing period, the lower jaws were dissected. Total area regenerated in the region of interest, total volume, bone to implant contact in the regenerated area, and volumetric changes were measured through histological, histomorphometrical and microcomputed tomography (microCT) techniques. The negative control group showed bone ingrowth inside the defect, with a partial collapse of the buccal bone. This was not observed in the biomaterial-treated groups. Defects treated with the xenograft showed 51.40% (SD 19.83) newly mineralized tissue, while those treated with alloplastic tricalcium showed 62.54% (SD 11.54) newly mineralized tissue; the control showed 71.52% (SD 6.46). Alloplastic tricalcium phosphate modified with monetite and zinc showed similar features in alveolar regeneration of defects to those treated with the xenograft or conventional GBR, but it showed an ideally higher rate of new mineralized tissue formation and accelerated resorption.

Guided bone regeneration with particulate vs. block xenogenic bone substitutes: a pilot cone beam computed tomographic investigation.

AIM: To test whether an equine bone substitute block used for guided bone regeneration (GBR) of peri-implant defects differs from bovine block or particulate bone substitutes regarding the hard and soft tissue contours of the augmented ridge. MATERIAL & METHODS: Two semi-saddle bone defects were prepared in each side of the mandible of eight dogs, and one titanium implant was inserted into every defect. The defects were randomly allocated to receive one of the following treatments: bone augmentation by GBR using (1) particulate deproteinized bovine bone mineral (DBBM) + a collagen membrane (CM), (2) block DBBM + CM, (3) equine bone substitute block + CM, and (4) empty controls. After 4 months, the jaws were scanned by means of cone beam computed tomography (CBCT). CBCT analysis was performed in one central and two lateral (mesial and distal) regions of interest (ROI) of each site evaluating the horizontal thickness of the augmented hard tissue (HThard tisue ) and the total thickness of hard and soft tissue (HTtotal ). The Wilcoxon-Pratt signed rank test was used for statistical analysis. RESULTS: In the majority of ROIs, equine and bovine blocks rendered significantly higher values in HThard tissue and HTtotal than controls (P < 0.05). Generally, equine blocks reached the highest values in HThard tissue and HTtotal followed by DBBM blocks and particulate DBBM. The differences in HThard tissue and HTtotal between GBR groups were not statistically significant (P > 0.05). In the central ROI, HThard tissue at the level of the implant shoulder measured 1.7 ± 1.4 mm for equine blocks, 1.7 ± 1.0 mm for DBBM blocks, 0.9 ± 1.2 mm for particulate DBBM, and 0 ± 0 mm for controls. The corresponding values in the lateral ROI reached 1.9 ± 1.1 mm for equine blocks, 1.2 ± 0.8 mm for DBBM blocks, 1.0 ± 0.9 mm for particulate DBBM, and 0 ± 0 mm for controls. CONCLUSIONS: GBR with bone substitute blocks lead to higher ridge dimensions than empty controls. The equine block with CM rendered the most favorable outcomes in hard and soft tissue contours followed by DBBM block and DBBM granulate with CM.

Guided bone regeneration at zirconia and titanium dental implants: a pilot histological investigation.

AIM: To test whether guided bone regeneration (GBR) of peri-implant defects at zirconia (ZrO2 ) implants differs from GBR at titanium (Ti) implants regarding the bone integration of the implant and of the grafting material. MATERIALS AND METHODS: Maxillary premolars and molars were extracted in seven dogs. After 5 months, four semi-saddle bone defects were created in each maxilla. Implant placement and simultaneous GBR were performed using the following randomly assigned modalities: (1) ZrO2 implant + deproteinized bovine bone mineral (DBBM) granules + a collagen membrane (CM), (2) ZrO2 implant + DBBM with 10% collagen matrix + CM, (3) ZrO2 implant + DBBM block + CM, and (4) Ti implant + DBBM granules + CM. After 3 months, one central histological section of each site was prepared. Histomorphometrical assessments were performed evaluating the augmented area (AA) within the former bone defect (primary outcome), the area of new bone (NB), bone substitute (BS), and non-mineralized tissue (NMT) within AA in mm2 . In addition, the distance between the most coronal bone-to-implant contact and the margin of the former bone defect (fBIC-DEF), and the bone-to-implant contact fraction (BIC) were measured in mm. RESULTS: AA measured 8.6 ± 4.0 mm2 for ZrO2 implant + DBBM granules, 4.7 ± 1.6 mm2 for ZrO2 implant + DBBM-collagen, 5.1 ± 1.9 mm2 for ZrO2 implant + DBBM block, and 7.6 ± 2.8 mm2 for Ti implant + DBBM granules. There were no statistically significant differences between the treatment modalities (P > 0.05). NB reached 2.0 ± 1.7 mm2 for ZrO2 implant + DBBM granules, 0.9 ± 0.9 mm2 for ZrO2 implant + DBBM-collagen, 2.1 ± 0.9 mm2 for ZrO2 implant + DBBM block, and 0.8 ± 0.6 mm2 for Ti implant + DBBM granules. fBIC-DEF amounted to 2.1 ± 1.7 mm2 for ZrO2 implant + DBBM granules, to 2.7 ± 1.1 mm2 for ZrO2 implant + DBBM-collagen, to 2.9 ± 1.2 mm2 for ZrO2 implant + DBBM block, and to 3.4 ± 0.4 mm2 for Ti implant + DBBM granules. BIC measured 70 ± 19% for ZrO2 implant + DBBM granules, 69 ± 22% for ZrO2 implant + DBBM-collagen, 77 ± 30% for ZrO2 implant + DBBM block, and 66 ± 27% for Ti implant + DBBM granules. CONCLUSIONS: The findings of the present pilot study suggest that zirconia and titanium implants grafted with DBBM granules and covered with a collagen membrane do not perform differently regarding the augmented ridge contour, the NB formation, and the implant osseointegration.

In vivo cardiomyocyte response to YTX- and AZA-1-induced damage: autophagy versus apoptosis.

Yessotoxins (YTX) and azaspiracids (AZAs) are marine toxins produced by phytoplanktonic dinoflagellates that get accumulated in filter feeding shellfish and finally reach human consumers through the food web. Both toxin classes are worldwide distributed, and food safety authorities have regulated their content in shellfish in many countries. Recently, YTXs and AZAs have been described as compounds with subacute cardiotoxic potential in rats owed to alterations of the cardiovascular function and ultrastructural heart damage. These molecules are also well known in vitro inducers of cell death. The aim of this study was to explore the presence of cardiomyocyte death after repeated subacute exposure of rats to AZA-1 and YTX for 15 days. Because autophagy and apoptosis are often found in dying cardiomyocytes, several autophagic and apoptotic markers were determined by western blot in heart tissues of these rats. The results showed that hearts from YTX-treated rats presented increased levels of the autophagic markers microtubule-associated protein light chain 3-II (LC3-II) and beclin-1, nevertheless AZA-1-treated hearts evidenced increased levels of the apoptosis markers cleaved caspase-3 and -8, cleaved PARP and Fas ligand. Therefore, while YTX-induced damage to the heart triggers autophagic processes, apoptosis activation occurs in the case of AZA-1. For the first time, activation of cell death signals in cardiomyocytes is demonstrated for these toxins with in vivo experiments, which may be related to alterations of the cardiovascular function.

Melatonin: A Review of Its Potential Functions and Effects on Dental Diseases.

Melatonin is a hormone synthesised and secreted by the pineal gland and other organs. Its secretion, controlled by an endogenous circadian cycle, has been proven to exert immunological, anti-oxidant, and anti-inflammatory effects that can be beneficial in the treatment of certain dental diseases. This article is aimed at carrying out a review of the literature published about the use of melatonin in the dental field and summarising its potential effects. In this review article, an extensive search in different databases of scientific journals was performed with the objective of summarising all of the information published on melatonin use in dental diseases, focussing on periodontal diseases and dental implantology. Melatonin released in a natural way into the saliva, or added as an external treatment, may have important implications for dental disorders, such as periodontal disease, as well as in the osseointegration of dental implants, due to its anti-inflammatory and osseoconductive effects. Melatonin has demonstrated to have beneficial effects on dental pathologies, although further research is needed to understand the exact mechanisms of this molecule.

Subacute Cardiotoxicity of Yessotoxin: In Vitro and in Vivo Studies.

Yessotoxin (YTX) is a marine phycotoxin produced by dinoflagellates and accumulated in filter feeding shellfish. Although no human intoxication episodes have been reported, YTX content in shellfish is regulated by many food safety authorities due to their worldwide distribution. YTXs have been related to ultrastructural heart damage in vivo, but the functional consequences in the long term have not been evaluated. In this study, we explored the accumulative cardiotoxic potential of YTX in vitro and in vivo. Preliminary in vitro evaluation of cardiotoxicity was based on the effect on hERG (human ether-a-go-go related gene) channel trafficking. In vivo experiments were performed in rats that received repeated administrations of YTX followed by recordings of electrocardiograms, arterial blood pressure, plasmatic cardiac biomarkers, and analysis of myocardium structure and ultrastructure. Our results showed that an exposure to 100 nM YTX for 12 or 24 h caused an increase of extracellular surface hERG channels. Furthermore, remarkable bradycardia and hypotension, structural heart alterations, and increased plasma levels of tissue inhibitor of metalloproteinases-1 were observed in rats after four intraperitoneal injections of YTX at doses of 50 or 70 µg/kg that were administered every 4 days along a period of 15 days. Therefore, and for the first time, YTX-induced subacute cardiotoxicity is supported by evidence of cardiovascular function alterations related to its repeated administration. Considering international criteria for marine toxin risk estimation and that the regulatory limit for YTX has been recently raised in many countries, YTX cardiotoxicity might pose a health risk to humans and especially to people with previous cardiovascular risk.

Marginal bone-level alterations of loaded zirconia and titanium dental implants: an experimental study in the dog mandible.

OBJECTIVES: The aim was to test whether or not the marginal bone-level alterations of loaded zirconia implants are similar to the bone-level alterations of a grade 4 titanium one-piece dental implant. MATERIALS AND METHODS: In six dogs, all premolars and the first molars were extracted in the mandible. Four months later, three zirconia implants (BPI, VC, ZD) and a control titanium one-piece (STM) implant were randomly placed in each hemimandible and left for transmucosal healing (baseline). Six months later, CAD/CAM crowns were cemented. Sacrifice was scheduled at 6-month postloading. Digital X-rays were taken at implant placement, crowns insertion, and sacrifice. Marginal bone-level alterations were calculated, and intra- and intergroup comparisons performed adjusted by confounding factors. RESULTS: Implants were successfully placed. Until crown insertion, two implants were fractured (one VC, one ZD). At sacrifice, 5 more implants were (partly) fractured (one BPI, four ZD), and one lost osseointegration (VC). No decementation of crowns occurred. All implant systems demonstrated a statistically significant (except VC) loss of marginal bone between baseline and crown insertion ranging from 0.29 mm (VC; P = 0.116) to 0.80 mm (ZD; P = 0.013). The estimated marginal bone loss between baseline and 6 months of loading ranged between 0.19 mm (BPI) and 1.11 mm (VC), being statistically significant for STM and VC only (P < 0.05). The changes in marginal bone levels were statistically significantly different between zirconia implants and control implants (STM vs. BPI P = 0.007; vs. VC P = 0.001; vs. ZD P = 0.011). CONCLUSIONS: Zirconia implants were more prone to fracture prior to and after loading with implant-supported crowns compared to titanium implants. Individual differences and variability in the extent of the bone-level changes during the 12-month study period were found between the different implant types and materials.

Histological analysis of loaded zirconia and titanium dental implants: an experimental study in the dog mandible.

OBJECTIVE: To assess whether or not peri-implant soft tissue dimensions and hard tissue integration of loaded zirconia implants are similar to those of a titanium implant. MATERIALS AND METHODS: In six dogs, two one-piece zirconia implants (VC, ZD), a two-piece zirconia implant (BPI) and a control one-piece titanium implant (STM) were randomly placed. CAD/CAM crowns were cemented at 6 months. Six months later, animals were killed and histomorphometric analyses were performed, including: the level of the mucosal margin, the extent of the peri-implant mucosa, the marginal bone loss and the bone-to-implant contact (BIC). Means of outcomes variables were calculated together with their corresponding 95% confidence intervals. RESULTS: In general, the mucosal margin was located coronally to the implant shoulder. The buccal peri-implant mucosa ranged between 2.64 ± 0.70 mm (VC) and 3.03 ± 1.71 mm (ZD) (for all median comparisons p > 0.05). The relative marginal bone loss ranged between 0.65 ± 0.61 mm (BPI) and 1.73 ± 1.68 mm (ZD) (buccal side), and between 0.55 ± 0.37 mm (VC) and 1.69 ± 1.56 mm (ZD) (lingual side) (p > 0.05). The mean BIC ranged between 78.6% ± 17.3% (ZD) and 87.9% ± 13.6% (STM) without statistically significant differences between the groups (p > 0.05). CONCLUSIONS: One- and two-piece zirconia rendered similar peri-implant soft tissue dimensions and osseointegration compared to titanium implants that were placed at 6 months of loading. Zirconia implants, however, exhibited a relatively high fracture rate.

Effects of diacerein on cartilage and subchondral bone in early stages of osteoarthritis in a rabbit model.

BACKGROUND: Osteoarthritis is thought to be the most prevalent chronic and disabling joint disease in animals and humans. At present, there is no ideal treatment option. The aim of this study was to assess the effects of the treatment with oral diacerein on articular cartilage, synovial membrane and subchondral bone in an experimental rabbit model of osteoarthritis by micro-CT evaluation and histological analysis. To this purpose, osteoarthritis was surgically induced on one knee of 16 rabbits using the contralateral knee as healthy controls. Treatment was started three weeks later and lasted eight weeks. Animals were divided into two groups for treatment: Placebo (treated daily with oral saline) and diacerein (treated orally with 1.5 mg/kg/day of diacerein). RESULTS: Sample analysis revealed that this model induced osteoarthritis in the operated knee joint. Osteoarthritis placebo group showed a significant increase in non-calcified cartilage thickness and volume with respect to the control placebo group and important changes in the synovial membrane; whereas the parameters measured in subchondral bone remained unchanged. In the osteoarthritis diacerein-treated group the results showed an improvement with respect to the OA placebo group in all parameters, although the results were not statistically significant. CONCLUSION: The results of this animal study suggested that the diacerein treatment for OA may be able to ameliorate the swelling and surface alterations of the cartilage and exert an anti-inflammatory effect on the synovial membrane, which might contribute to OA improvement, as well as an anabolic effect on subchondral trabecular bone.

Marginal bone and soft tissue behavior following platform switching abutment connection/disconnection--a dog model study.

OBJECTIVE: The effect on the marginal peri-implant tissues following repeated platform switching abutment removal and subsequent reconnection was studied. MATERIAL AND METHODS: Six adult female Beagle dogs were selected, and Pm3 and Pm4 teeth, both left and right sides, were extracted and the sites healed for 3 months. At this time, 24 bone level (BL) (Straumann, Basel, Switzerland) Ø 3.3/8 mm implants were placed, 2 in each side on Pm3 and Pm4 regions. In one side (control group), 12 bone level conical Ø 3.6 mm healing abutments and, on the other side (test group), 12 Narrow CrossFit (NC) multibase abutments (Straumann) , Basel, Switzerland) were connected at time of implant surgery. On test group, all prosthetic procedures were carried out direct to multibase abutment without disconnecting it, where in the control group, the multibase abutment was connected/disconnected five times (at 6/8/10/12/14 weeks) during prosthetic procedures. Twelve fixed metal bridges were delivered 14 weeks after implant placement. A cleaning/control appointment was scheduled 6 months after implant placement. The animals were sacrificed at 9 months of the study. Clinical parameters and peri-apical x-rays were registered in every visit. Histomorphometric analysis was carried out for the 24 implants. The distance from multibase abutment shoulder to the first bone implant contact (S-BIC) was defined as the primary histomorphometric parameter. RESULTS: Wilcoxon comparison paired test (n = 6) found no statistically significant differences (buccal P = 0.917; Lingual P = 0.463) between test and control groups both lingually and buccally for S-BIC distance. Only Pm3 buccal aBE-BC (distance from the apical end of the barrier epithelium to the first bone implant contact) (P = 0.046) parameter presented statistically significant differences between test and control groups. Control group presented 0.57 mm more recession than test group, being this difference statistically significant between the two groups (P < 0.001). CONCLUSION: It can be conclude, within the limits of this animal study, that the connection/disconnection of platform switching abutments during prosthetic phase of implant treatment does not induce bone marginal absorption. Furthermore, it may present a negative influence in the buccal connective tissue attachment that becomes shorter anyway preventing marginal hard tissue resorption, especially in thin biotypes.

Comparison of various SYSADOA for the osteoarthritis treatment: an experimental study in rabbits.

BACKGROUND: Osteoarthritis is thought to be the most prevalent chronic and disabling joint disease in animals and humans and its treatment is a major orthopaedic challenge because there is no ideal drug treatment to preserve joint structure and function, as well as to ameliorate the symptomatology of the disease. The aim of the present study was to assess, using histology, histomorphometry and micro-CT, the effects of the treatment with several drugs of the SYSADOA group and a bisphosphonate in a model of early osteoarthritis, comparing all the results obtained. METHODS: Osteoarthritis was surgically induced by anterior cruciate ligament transection and partial meniscectomy on one knee of 56 rabbits; treatment was started three weeks after surgery and lasted 8 weeks; at the end of this period, the animals were sacrificed. Animals were divided into seven groups (8 animals each), one for each regimen of treatment (glucosamine sulfate, chondroitin sulfate, hyaluronic acid, diacerein, risedronate and a combination of risedronate and glucosamine) and one for the control (placebo-treated) group. Following sacrifice, femoral osteochondral cylinders and synovial membrane samples were obtained for their evaluation by qualitative and quantitative histology and micro-CT. RESULTS: The model induced osteoarthritic changes in the knee joints and none of the treatments showed a significantly better efficacy over the others. Regarding cartilage thickness and volume, all the treatments achieved scores halfway between control groups, without statistical differences. Regarding the synovial membrane, diacerein and risedronate showed the best anti-inflammatory profile, whereas glucosamine and chondroitin did not present any effect standing the hyaluronic acid results between the others. Regarding the subchondral bone, there were no differences in thickness or volume, but risedronate, diacerein and hyaluronic acid seemed to have considerably modified the orientation of the trabecular lattice. CONCLUSIONS: Out of the different drugs evaluated in the study for OA treatment, diacerein and risedronate showed, in all the parameters measured, a better profile of effectiveness; hyaluronic acid ameliorated cartilage swelling and promoted bone formation, but with a poor synovial effect; and finally, chondroitin and glucosamine sulfate prevented cartilage swelling in a similar way to the others, but had no effect on cartilage surface, synovial membrane or subchondral bone.

Effects of glucosamine and risedronate alone or in combination in an experimental rabbit model of osteoarthritis.

BACKGROUND: The osteoarthritis (OA) treatment in humans and in animals is a major orthopaedic challenge because there is not an ideal drug for preserving the joint structure and function. The aim of this study was to assess the effects of the treatment with oral glucosamine and risedronate alone or in combination on articular cartilage, synovial membrane and subchondral bone in an experimental rabbit model of OA. Osteoarthritis was surgically induced on one knee of 32 New Zealand White rabbits using the contralateral as healthy controls. Three weeks later treatments were started and lasted 8 weeks. Animal were divided in four groups of oral treatment: the first group received only saline, the second 21.5 mg/kg/day of glucosamine sulfate, the third 0.07 mg/kg/day of risedronate; and the fourth group both drugs simultaneously at the same dosages. Following sacrifice femurs were removed and osteochondral cylinders and synovial membrane were obtained for its histological and micro-CT evaluation. RESULTS: Sample analysis revealed that the model induced osteoarthritic changes in operated knees. OA placebo group showed a significant increase in cartilage thickness respect to the control and inflammatory changes in synovial membrane; whereas subchondral bone structure and volumetric bone mineral density remained unchanged. All the treated animals showed an improvement of the cartilage swelling independent of the drug used. Treatment with glucosamine alone seemed to have no effect in the progression of cartilage pathology while risedronate treatment had better results in superficial fibrillation and in resolving the inflammatory changes of the tissues, as well as modifying the orientation of trabecular lattice. The combination of both compounds seemed to have additive effects showing better results than those treated with only one drug. CONCLUSIONS: The results of this animal study suggested that glucosamine sulfate and risedronate treatment alone or in combination may be able to stop cartilage swelling. The risedronate treatment could partially stop the fibrillation and the inflammation of synovial membrane as well as modify the orientation of trabeculae in healthy and in osteoarthritic knees.

In vivo arrhythmogenicity of the marine biotoxin azaspiracid-2 in rats.

Azaspiracids (AZAs) are marine biotoxins produced by the dinoflagellate Azadinium spinosum that accumulate in several shellfish species. Azaspiracid poisoning episodes have been described in humans due to ingestion of AZA-contaminated seafood. Therefore, the contents of AZA-1, AZA-2 and AZA-3, the best-known analogs of the group, in shellfish destined to human consumption have been regulated by food safety authorities of many countries to protect human health. In vivo and in vitro toxicological studies have described effects of AZAs at different cellular levels and on several organs, however, AZA target remains unknown. Very recently, AZAs have been demonstrated to block the hERG cardiac potassium channel. In this study, we explored the potential cardiotoxicity of AZA-2 in vivo. The effects of AZA-2 on rat electrocardiogram (ECG) and cardiac biomarkers were evaluated for cardiotoxicity signs besides corroborating the hERG-blocking activity of AZA-2. Our results demonstrated that AZA-2 does not induce QT interval prolongation on rat ECGs in vivo, in spite of being an in vitro blocker of the hERG cardiac potassium channel. However, AZA-2 alters the heart electrical activity causing prolongation of PR intervals and the appearance of arrhythmias. More studies will be needed to clarify the mechanism by which AZA-2 causes these ECG alterations; however, the potential cardiotoxicity of AZAs demonstrated in this in vivo study should be taken into consideration when evaluating the possible threat that these toxins pose to human health, mainly for individuals with pre-existing cardiovascular disease when regulated toxin limits are exceeded.

Enhanced Bone Healing in Critical-Sized Rabbit Femoral Defects: Impact of Helical and Alternate Scaffold Architectures.

This study investigates the effect of scaffold architecture on bone regeneration, focusing on 3D-printed polylactic acid-bioceramic calcium phosphate (PLA-bioCaP) composite scaffolds in rabbit femoral condyle critical defects. We explored two distinct scaffold designs to assess their influence on bone healing and scaffold performance. Structures with alternate (0°/90°) and helical (0°/45°/90°/135°/180°) laydown patterns were manufactured with a 3D printer using a fused deposition modeling technique. The scaffolds were meticulously characterized for pore size, strut thickness, porosity, pore accessibility, and mechanical properties. The in vivo efficacy of these scaffolds was evaluated using a femoral condyle critical defect model in eight skeletally mature New Zealand White rabbits. Then, the results were analyzed micro-tomographically, histologically, and histomorphometrically. Our findings indicate that both scaffold architectures are biocompatible and support bone formation. The helical scaffolds, characterized by larger pore sizes and higher porosity, demonstrated significantly greater bone regeneration than the alternate structures. However, their lower mechanical strength presented limitations for use in load-bearing sites.

Use of 3D-printed polylactic acid/bioceramic composite scaffolds for bone tissue engineering in preclinical in vivo studies: A systematic review.

3D-printed composite scaffolds have emerged as an alternative to deal with existing limitations when facing bone reconstruction. The aim of the study was to systematically review the feasibility of using PLA/bioceramic composite scaffolds manufactured by 3D-printing technologies as bone grafting materials in preclinical in vivo studies. Electronic databases were searched using specific search terms, and thirteen manuscripts were selected after screening. The synthesis of the scaffolds was carried out using mainly extrusion-based techniques. Likewise, hydroxyapatite was the most used bioceramic for synthesizing composites with a PLA matrix. Among the selected studies, seven were conducted in rats and six in rabbits, but the high variability that exists regarding the experimental process made it difficult to compare them. Regarding the results, PLA/Bioceramic composite scaffolds have shown to be biocompatible and mechanically resistant. Preclinical studies elucidated the ability of the scaffolds to be used as bone grafts, allowing bone growing without adverse reactions. In conclusion, PLA/Bioceramics scaffolds have been demonstrated to be a promising alternative for treating bone defects. Nevertheless, more care should be taken when designing and performing in vivo trials, since the lack of standardization of the processes, which prevents the comparison of the results and reduces the quality of the information. STATEMENT OF SIGNIFICANCE: 3D-printed polylactic acid/bioceramic composite scaffolds have emerged as an alternative to deal with existing limitations when facing bone reconstruction. Since preclinical in vivo studies with animal models represent a mandatory step for clinical translation, the present manuscript analyzed and discussed not only those aspects related to the selection of the bioceramic material, the synthesis of the implants and their characterization. But provides a new approach to understand how the design and perform of clinical trials, as well as the selection of the analysis methods, may affect the obtained results, by covering authors' knowledgebase from veterinary medicine to biomaterial science. Thus, this study aims to systematically review the feasibility of using polylactic acid/bioceramic scaffolds as grafting materials in preclinical trials.

Modification of the Marmarou and Foda model of diffuse axonal injury (DAI) improves percentage survival of rats at 24 h and increases the amount of DAI identified.

More than two decades ago, Marmarou published a valid model for producing diffuse axonal injury (DAI) in rats. Since then, both mild and severe injuries have been obtained by researchers using the original method and a weight of 450 g. However, the diffuse brain injuries produced in rats were only similar to those seen in humans when the rats sustained severe brain injuries. In these cases, rat mortality in the original article was around 50%, and the cause of death was prolonged apnea post-impact. Rat survival after impact is critical for studying the progression of DAI. In order to explain the cause of death in human victims with cranial trauma who do not show gross brain injury, testing for the presence of DAI is essential. Thus, in order to minimize local and cervical injuries to increase rat survival, attention should be paid to the following aspects: a wider head protector disc should be used, the head of the rat should be elevated at the time of impact, and the foam bed should be soft enough to allow the movement caused by acceleration. With our modified method, rat survival increased by 30% compared to the original model (80% versus 50%). Moreover, 85.7% of rats demonstrated DAI after 24 h of survival. With these modifications, injuries appear in the same locations as in humans; thus, the method is suitable for the study of traumatic DAI in humans.