Clinical anatomy of the meniscus in animal models: pros and cons.

Nowadays, despite the possibility to use in vitro or computer models in research, animal models are still essential. Different animal models are available for meniscal repair investigation. Although a unique perfect model for the structure of the human's knee does not exist, the choice of the proper animal model is crucial for a correct research. The principal animal models in the meniscal repair are sheep, goats, pigs and dogs. Each of these has pros and cons for their utilization. Analysing each pro and con is essential for optimizing the choice of the animal model, which depends on the experimental question, avoiding unnecessary waste of resources and minimizing the animal suffering, according to the Russell and Burch's three "Rs" principles (Reduce, Refine and Recycle). In this concise review, we resume the meniscus anatomical features of the main large animals, to help choose the most suitable animal model for subsequent studies on meniscal repair.

Effect of chronotype on motor skills specific to soccer in adolescent players.

Circadian rhythms influence daily behavior, psychological and physiological functions, as well as physical performance. Three chronotypes are distinguished according to the preferences people typically display for activity at certain times of day: Morning, Neither, and Evening types (M-, N- and E-types). The chronotype changes with age: eveningness tends to be stronger in youth and morningness in older age. The progressive shift toward eveningness during adolescence creates misalignment with morning society schedules and can lead to a deterioration in intellectual and physical performance. Soccer is one of the world's most popular sports practiced by adolescents and soccer workouts are usually held after school in the afternoon or evening. Performance in soccer is related to a host of factors, including physiological variables and motor skills that have a circadian variation. The aim of this study was to determine the effect of chronotype on motor skills specific to soccer, specifically whether agility, aerobic endurance, and explosive power differ among the three chronotypes in relation to the time of day. For this study 141 adolescent soccer players filled in the Morningness-Eveningness Questionnaire (MEQ) for the assessment of chronotype. A subsample of 75 subjects, subdivided in M-types (n= 25), E-types (n= 25), and N-types (n= 25), performed three tests (Sargent Jump Test - SJT, Illinois Agility Test - IAT, and 6-Minutes Run Test - 6MRT) at a morning and an evening training session (9:00 am and 6:00 pm). Mixed ANOVA was used to test the interactions between chronotypes, physical performance, and time. On all tests, better performance during the morning than the evening session was observed for the M-types (p< .05), whereas the E-types performed better in the evening than in the morning session (p< .05), and no differences in test performance were detected for the N-types. These findings underline the importance of a correct chronobiological approach to sports training. Scheduling training sessions according to an athlete's circadian preferences could be a valid strategy to enhance performance.

Animal models for cartilage repair.

Cartilage lesions still represent an unsolved problem: despite the efforts of the basic and translational research, the regeneration of this tissue is far from being reached (1-3). Articular cartilage lesions can be divided in two main groups: superficial or partial defects and full-thickness defects (4, 5). Partial lesions are not able to self-heal because multipotent cells from the bone marrow cannot reach the area leading to a progressive degeneration of the tissue (6). Conversely, full-thickness injuries possess greater chances to heal because subchondral bone involvement allows for the migration of mesenchymal cells, which fill the damaged area (7, 8). However, healing occurs through the formation of a fibrocartilaginous tissue, which has different biomechanical and biological properties (9). Native hyaline cartilage has indeed specific biomechanical properties, which confer resistance to compressive and shear stresses; the reparative fibrocartilaginous tissue lacks these abilities, therefore, the surrounding healthy cartilage progressively degenerates. In the past years, several therapeutic strategies have been developed to restore the damaged cartilage, bone marrow stimulation (chondroabrasion, drilling, micro- or nano-fractures) and more recently, tissue engineering approaches (10-14). Some of these latter procedures have already been applied in clinical practice such as matrix-induced autologous chondrocyte implantation (MACI) (15) or osteochondral scaffold implantation (16). Generally, tissue engineering approaches are based on the combination of three main elements: cells (i.e. primary chondrocytes or multipotent mesenchymal cells), biocompatible scaffolds (i.e. polymers, composites, ceramics) and signaling molecules (i.e. growth factors). Moreover, several culture conditions (i.e. static or dynamic cultures) and biomechanical stimuli can be applied during the in vitro culture to promote tissue maturation (17-19). However, an in vivo culture is mandatory to validate a new engineered construct as the in vitro phase lacks the essential in vivo environmental stimuli and because the in vivo culture allows for the testing of the biocompatibility and safety of a new material (18, 19). Moreover, preclinical animal models are crucial to understand the molecular mechanisms of cartilage lesions favoring the development of new regenerative strategies (20, 21). in vivo studies on animal models should focus on the analysis of the cellular component, analyzing the maintenance of the cellular phenotype and the tumorigenicity; on the evaluation of the biocompatibility, toxicity and degradation of the biomaterial and on the assessment of the engineered construct. In this manuscript, we will review the most common preclinical animal models, which are used to understand cartilage biology and therefore to develop new tissue engineering strategies. We will focus on both small and large animal models highlighting their peculiarities, advantages and drawbacks.

External fixation versus titanium endomedullary nail in the treatment of diaphyseal fractures of the lower limb in pediatric age: our experience.

In the past, the use of external fixation technique (FE) in children was limited, as the patient's compliance to the treatment was scarce due to an important visual impact for the little patient. With the evolution of the surgical approach and the technology of fixators, we have been able to considerably implement the treatment possibilities, thus allowing for an immediate load bearing of the operated limb and for the early mobilization of the joints. The FE technique does not represent an overcoming of classical synthesis techniques by internal fixation with elastic intramedullary nails, but it simply offers a valid treatment alternative to selected cases. In this work, we radiologically and clinically evaluated pediatric patients treated with FE for diaphyseal fractures of the lower limb and we compared them with patients treated with standard Titanium Endomedullary Nail (TEN) techniques. Our results confirmed that FE is a valid alternative treatment for these types of fractures.

The analysis of different scaffolds and the benefit of fibrin glue for tendon tissue engineering at different culture times.

This study evaluated a tendon substitute model. Tenocytes were isolated from pig Achilles tendon, seeded onto scaffolds (Opocrin 2%, Typeone 3% and Symatese 2%) and studied by histology, immunofluorescence for collagen type 1 and 3 and biochemical analysis to assess cellularity. The permeability of these compounds was evaluated in the presence or absence of fibrin glue. Opocrin 2% was the best choice for cellular distribution within the scaffolds, which were then cultured for T0, T4, T7 and T10 days. Fibrin glue has been strongly supportive for the survival of cells with a significant increase in DNA content at T10 (P<0.05). Moreover, the synthetic activity of fibrin-free scaffolds was always negative. Lastly, a progressive increase in collagen 1 and 3 with fibrin-glue was observed. However, static culture is not sufficient to support long-term cellular activities and at T10 there is still a lack of organized matrix similar to the native tissue.

Synthesis and chemical characterization of several perfluorinated sialic acid glycals and evaluation of their in vitro antiviral activity against Newcastle disease virus.

Newcastle Disease Virus (NDV), belonging to the Paramyxoviridae family, causes a serious infectious disease in birds, resulting in severe losses in the poultry industry every year. Haemagglutinin neuraminidase glycoprotein (HN) has been recognized as a key protein in the viral infection mechanism, and its inhibition represents an attractive target for the development of new drugs based on sialic acid glycals, with the 2-deoxy-2,3-didehydro-d-N-acetylneuraminic acid (Neu5Ac2en) as their backbone. Herein we report the synthesis of several Neu5Ac2en glycals and of their perfluorinated C-5 modified derivatives, including their respective stereoisomers at C-4, together with evaluation of their in vitro antiviral activity. While all synthesized compounds were found to be active HN inhibitors in the micromolar range, we found that their potency was influenced by the chain-length of the C-5 perfluorinated acetamido functionality. Thus, the binding modes of the inhibitors were also investigated by performing a docking study. Moreover, the perfluorinated glycals were found to be more active than the corresponding normal C-5 acylic derivatives. Finally, cell-cell fusion assays on NDV infected cells revealed that the addition of a newly synthesized C-4α heptafluorobutyryl derivative almost completely inhibited NDV-induced syncytium formation.

Allogeneic Umbilical Cord-Derived Mesenchymal Stem Cells as a Potential Source for Cartilage and Bone Regeneration: An In Vitro Study.

Umbilical cord (UC) may represent an attractive cell source for allogeneic mesenchymal stem cell (MSC) therapy. The aim of this in vitro study is to investigate the chondrogenic and osteogenic potential of UC-MSCs grown onto tridimensional scaffolds, to identify a possible clinical relevance for an allogeneic use in cartilage and bone reconstructive surgery. Chondrogenic differentiation on scaffolds was confirmed at 4 weeks by the expression of sox-9 and type II collagen; low oxygen tension improved the expression of these chondrogenic markers. A similar trend was observed in pellet culture in terms of matrix (proteoglycan) production. Osteogenic differentiation on bone-graft-substitute was also confirmed after 30 days of culture by the expression of osteocalcin and RunX-2. Cells grown in the hypertrophic medium showed at 5 weeks safranin o-positive stain and an increased CbFa1 expression, confirming the ability of these cells to undergo hypertrophy. These results suggest that the UC-MSCs isolated from minced umbilical cords may represent a valuable allogeneic cell population, which might have a potential for orthopaedic tissue engineering such as the on-demand cell delivery using chondrogenic, osteogenic, and endochondral scaffold. This study may have a clinical relevance as a future hypothetical option for allogeneic single-stage cartilage repair and bone regeneration.

The meniscus vascularization: the direct correlation with tissue composition for tissue engineering purposes.

Meniscal lesions still represent an unsolved problem in clinical practice. Like the articular cartilage, meniscus has a scarce healing potential. Thus, when this tissue is damaged, the joint biomechanics is completely altered, leading to the development and progression of premature osteoarthritis. Therefore, in the last years, several tissue-engineering strategies have been developed to regenerate the meniscus with debated results. The comprehension of complex processes underlying meniscus maturation and structure is essential for a correct approach for the generation of a biomimetic meniscal substitute. In this chapter, we will first review the morphology of the meniscus during growth, focusing on the unique pattern of vascularization, and then we will discuss the most common tissue engineering strategies for meniscus repair.

Cardiovascular adaptation to mudpack therapy in hypertensive subjects treated with different antihypertensive drugs.

OBJECTIVE: In selected hypertensive subjects, cardiovascular adaptation to warm environments may be inadequate or even harmful: heating associated to mudpack therapy may cause unexpected hypotension. How different antihypertensive drugs may affect the cardiovascular response to mudpack therapy is poorly studied. AIMS: To evaluate the effects of ß-blockers and angiotensin II receptor antagonists/ACE inhibitors on the acute cardiovascular adaptation to mudpack treatment in SPA in elderly hypertensive patients. PATIENTS AND METHODS: Thirty-one elderly subjects were divided in normotensive subjects (N; n=10) and hypertensive patients treated with ACE-inhibitors/Angiotensin II receptor antagonists (HTA; n=12) or with selective ß1-blockers (HTB; n=9). Systolic (SBP) and diastolic (DBP) blood pressure were continuously recorded (10 min) in supine position, immediately before and during mudpack treatment (40°C). Heart rate (HR), stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were assessed. RESULTS: During mudpack treatment SBP did not significantly change in both HTA and N groups (132±11 and 112±13 mmHg, respectively), but significantly decreased in HTB (111±18 mmHg, p < 0.01 vs baseline) patients. HR increased in all groups (HTA: 72±10 bpm; HTB: 65±6 bpm; N: 70±10 bpm; p < 0.01 vs baseline). A significant reduction (p < 0.01 vs baseline) in SV and CO occurred in HTB, but not in HTA and N groups. TPR significantly increased in HTB (1335±464 dyn.s.cm-5, p < 0.01 vs baseline) but not in HTA and N subjects (1389±385 dyn.s.cm-5 and 1245±323 dyn.s.cm-5, respectively). CONCLUSIONS: Mud treatment did not cause relevant haemodynamic changes in normotensive and HTA-treated hypertensive subjects. Conversely, ß-blocking treatment apparently limited the cardiovascular adaptation to thermic stress, through a possible reduction in myocardial contractility, thereby, causing a significant decrease, although not dangerous, in systolic blood pressure.

Effects of a 25-km trial on psychological, physiological and stroke characteristics of short- and mid-distance swimmers.

AIM: The aim of this paper was to evaluate the effects of a very long distance swimming task on psychological, biomechanical and physiological responses. Eight swimmers (age 21.0 ± 1.2 years; stature 1.80 ± 0.07 m; body mass 76.7 ± 11.0 kg; means ± SD) participated in a 25-km trial in a swimming pool. METHODS: Before and immediately after the trial, swimmers underwent a 50-m sprint test, during which we assessed velocity, stroke rate (SR), stroke length (SL) and psychological condition (rate of perceived exertion [RPE] and profile of mood state [POMS] questionnaire). During the 25-km trial we determined also elbow angle, heart rate (HR) and lactate concentration ([La]). RESULTS: Velocity, SR and SL during the sprint test after the trial decreased compared to before from 1.91 ± 0.01 m·s⁻¹, 0.94 ± 0.01 cycles·s⁻¹ and 1.99 ± 0.02 m·cycle⁻¹ to 1.45 ± 0.01 m·s⁻¹, 0.78 ± 0.01 cycles·s⁻¹ and 1.84 ± 0.03 m·cycle⁻¹, respectively (P<0.05). During the 25-km trial, velocity and SL decreased significantly, while SR and elbow angle did not change. Velocity and SR during the sprint test after the trial were significantly higher than those during the trial. RPE and fatigue (POMS subscale) increased significantly, while the other negative POMS subscales and vigor decreased significantly. HR decreased significantly at 20 km, then increasing significantly at 25 km, while [La] did not change. CONCLUSION: These results suggest that, despite the occurrence of fatigue, as evidenced by the drop in velocity and changes in psychological profile, swimmers were able to complete the 25-km trial by adopting a conservative pacing, unveiling also a reserve in maximum performance.