Evaluation of the effect of glucosamine on an experimental rat osteoarthritis model

AimsTo investigate the in vivo effect of glucosamine on articular cartilage in osteoarthritis (OA), we evaluated serum biomarkers such as CTX-II (type II collagen degradation) and CPII (type II collagen synthesis) as well as histopathological changes (Mankin score, toluidine blue staining of proteoglycans in an experimental OA model using rats.Main methodsOA was surgically induced in the knee joint by anterior cruciate ligament transection (ACLT) in rats. Animals were divided into three groups: sham-operated group (Sham), ACLT group without GlcN administration (? GlcN) and ACLT group with oral administration of glucosamine hydrochloride (+ GlcN; 1000 mg/kg/day for 56 days).Key findingsACLT induced macroscopic erosive changes on the surfaces of articular cartilage and histological damages such as increase of Mankin score. Of note, glucosamine administration substantially suppressed the macroscopic changes, although the effect on Mankin score was not significant. In addition, serum CTX-II levels were elevated in ?GlcN group compared to that in Sham group after the operation. Of importance, the increase of CTX-II was significantly suppressed by GlcN administration. Moreover, serum CP-II levels were substantially increased in + GlcN group compared to those in Sham and ? GlcN groups after the operation.SignificanceGlcN has a potential to exert a chondroprotective action on OA by inhibiting type II collagen degradation and enhancing type II collagen synthesis in the articular cartilage.     

Evidence against proteoglycan mediated collagen fibril load transmission and dynamic viscoelasticity in tendon

The glycosaminoglycan (GAG) dermatan sulfate and chondroitin sulfate side-chains of small leucine-rich proteoglycans have been increasingly posited to act as molecular cross links between adjacent collagen fibrils and to directly contribute to tendon elasticity. GAGs have also been implicated in tendon viscoelasticity, supposedly affecting frictional loss during elongation or fluid flow through the extra cellular matrix. The current study sought to systematically test these theories of tendon structure–function by investigating the mechanical repercussions of enzymatic depletion of GAG complexes by chondroitinase ABC in a reproducible tendon structure–function model (rat tail tendon fascicles). The extent of GAG removal (at least 93%) was verified by relevant spectrophotometric assays and transmission electron microscopy. Dynamic viscoelastic tensile tests on GAG depleted rat tail tendon fascicle were not mechanically different from controls in storage modulus (elastic behavior) over a wide range of strain-rates (0.05, 0.5, and 5% change in length per second) in either the linear or nonlinear regions of the material curve. Loss modulus (viscoelastic behavior) was only affected in the nonlinear region at the highest strain-rate, and even this effect was marginal (19% increased loss modulus, p = 0.035). Thus glycosaminoglycan chains of small leucine-rich proteoglycans do not appear to mediate dynamic elastic behavior nor do they appear to regulate the dynamic viscoelastic properties in rat tail tendon fascicles.     

The region-dependent biphasic viscoelastic properties of human temporomandibular joint discs under confined compression

The objective of this study was to determine the biphasic viscoelastic properties of human temporomandibular joint (TMJ) discs, correlate these properties with disc biochemical composition, and examine the relationship between these properties and disc dynamic behavior in confined compression. The equilibrium aggregate modulus (H_A), hydraulic permeability (k), and dynamic modulus were examined between five disc regions. Biochemical assays were conducted to quantify the amount of water, collagen, and glycosaminoglycan (GAG) content in each region. The creep tests showed that the average equilibrium moduli of the intermediate, lateral, and medial regions were significantly higher than for the anterior and posterior regions (69.75±11.47 kPa compared to 22.0±5.15 kPa). Permeability showed the inverse trend with the largest values in the anterior and posterior regions (8.51±1.36×10^?15 m⁴/Ns compared with 3.75±0.72×10^?15 m⁴/Ns). Discs were 74.5% water by wet weight, 62% collagen, and 3.2% GAG by dry weight. Regional variations were only observed for water content which likely results in the regional variation in biphasic mechanical properties. The dynamic modulus of samples during confined compression is related to the aggregate modulus and hydraulic permeability of the tissue. The anterior and posterior regions displayed lower complex moduli over all frequencies (0.01–3 Hz) with average moduli of 171.8–609.3 kPa compared with 454.6–1613.0 kPa for the 3 central regions. The region of the TMJ disc with higher aggregate modulus and lower permeability had higher dynamic modulus. Our results suggested that fluid pressurization plays a significant role in the load support of the TMJ disc under dynamic loading conditions.     

Tissue viscoelasticity is related to tissue composition but may not fully predict the apparent-level viscoelasticity in human trabecular bone – An experimental and finite element study

Trabecular bone is viscoelastic under dynamic loading. However, it is unclear how tissue viscoelasticity controls viscoelasticity at the apparent-level. In this study, viscoelasticity of cylindrical human trabecular bone samples (n = 11, male, age 18–78 years) from 11 proximal femurs were characterized using dynamic and stress-relaxation testing at the apparent-level and with creep nanoindentation at the tissue-level. In addition, bone tissue elasticity was determined using scanning acoustic microscope (SAM). Tissue composition and collagen crosslinks were assessed using Raman micro-spectroscopy and high performance liquid chromatography (HPLC), respectively. Values of material parameters were obtained from finite element (FE) models by optimizing tissue-level creep and apparent-level stress-relaxation to experimental nanoindentation and unconfined compression testing values, respectively, utilizing the second order Prony series to depict viscoelasticity. FE simulations showed that tissue-level equilibrium elastic modulus (E_eq) increased with increasing crystallinity (r = 0.730, p = .011) while at the apparent-level it increased with increasing hydroxylysyl pyridinoline content (r = 0.718, p = .019). In addition, the normalized shear modulus g₁ (r = −0.780, p = .005) decreased with increasing collagen ratio (amide III/CH₂) at the tissue-level, but increased (r = 0.696, p = .025) with increasing collagen ratio at the apparent-level. No significant relations were found between the measured or simulated viscoelastic parameters at the tissue- and apparent-levels nor were the parameters related to tissue elasticity determined with SAM. However, only E_eq, g₂ and relaxation time τ₁ from simulated viscoelastic values were statistically different between tissue- and apparent-levels (p < .01). These findings indicate that bone tissue viscoelasticity is affected by tissue composition but may not fully predict the macroscale viscoelasticity in human trabecular bone.     

How symmetric are metal-on-metal hip resurfacing patients during gait? Insights for the rehabilitation

Metal-on-metal hip resurfacing patients demonstrate hip biomechanics closer to normal in comparison to total hip arthroplasty during gait. However, it is not clear how symmetric is the gait of hip resurfacing patients. Biomechanical data of 12 unilateral metal-on-metal hip resurfacing participants were collected during gait at a mean time of 45 months (SD 24) after surgery. Ankle, knee, hip, pelvis and trunk kinematics and kinetics of both sides were measured with a motion and force-capture system. Principal component analysis and mean hypothesis’ tests were used to compare the operated and healthy sides. The operated side had prolonged ankle eversion angle during late stance and delayed increased ankle inversion angle during early swing (p = 0.008; effect size = 0.70), increased ankle inversion moment during late stance (p = 0.001; effect size = 0.78), increased knee adduction angle during swing (p = 0.044; effect size = 0.57), decreased knee abduction moment during stance (p = 0.05; effect size = 0.40), decreased hip range of motion in the sagittal plane (p = 0.046; effect size = 0.56), decreased range of hip abduction moment during stance (p = 0.02; effect size = 0.63), increased hip range of motion in the transverse plane (p = 0.02; effect size = 0.62), decreased hip internal rotation moment during the transition from loading response to midstance (p = 0.001; effect size = 0.81) and increased trunk ipsilateral lean (p = 0.03; effect size = 0.60). Therefore, hip resurfacing patients have some degree of asymmetry in long term, which may be related to hip weakness and decreased range of motion, to foot misalignments and to strategies implemented to reduce loading on the operated hip. Interventions such as muscle strengthening and stretching, insoles and gait feedback training may help improving symmetry following hip resurfacing.     

Interlimb symmetry of dynamic knee joint stiffness and co-contraction is maintained in early stage knee osteoarthritis

Individuals with knee OA often exhibit greater co-contraction of antagonistic muscle groups surrounding the affected joint which may lead to increases in dynamic joint stiffness. These detrimental changes in the symptomatic limb may also exist in the contralateral limb, thus contributing to its risk of developing knee osteoarthritis. The purpose of this study is to investigate the interlimb symmetry of dynamic knee joint stiffness and muscular co-contraction in knee osteoarthritis.Muscular co-contraction and dynamic knee joint stiffness were assessed in 17 subjects with mild to moderate unilateral medial compartment knee osteoarthritis and 17 healthy control subjects while walking at a controlled speed (1.0 m/s). Paired and independent t-tests determined whether significant differences exist between groups (p < 0.05).There were no significant differences in dynamic joint stiffness or co-contraction between the OA symptomatic and OA contralateral group (p = 0.247, p = 0.874, respectively) or between the OA contralateral and healthy group (p = 0.635, p = 0.078, respectively). There was no significant difference in stiffness between the OA symptomatic and healthy group (p = 0.600); however, there was a slight trend toward enhanced co-contraction in the symptomatic knees compared to the healthy group (p = 0.051).Subjects with mild to moderate knee osteoarthritis maintain symmetric control strategies during gait.     

Optimal whole-body vibration settings for muscle strength and power enhancement in human knee extensors

This study compared the effects of 6-week whole-body vibration (WBV) training programs with different frequency and peak-to-peak displacement settings on knee extensor muscle strength and power. The underlying mechanisms of the expected gains were also investigated. Thirty-two physically active male subjects were randomly assigned to a high-frequency/high peak-to-peak displacement group (HH; n = 12), a low-frequency/low peak-to-peak displacement group (LL; n = 10) or a sham training group (SHAM; n = 10). Maximal voluntary isometric, concentric and eccentric torque of the knee extensors, maximal voluntary isometric torque of the knee flexors, jump performance, voluntary muscle activation, and contractile properties of the knee extensors were assessed before and after the training period. Significant improvement in knee extensor eccentric voluntary torque (P < 0.01), knee flexor isometric voluntary torque (P < 0.05), and jump performance (P < 0.05) was observed only for HH group. Regardless of the group, knee extensor muscle contractile properties (P < 0.05) were enhanced. No modification was observed for voluntary muscle activation or electrical activity of agonist and antagonist muscles. We concluded that high-frequency/high peak-to-peak displacement was the most effective vibration setting to enhance knee extensor muscle strength and jump performance during a 6-week WBV training program and that these improvements were not mediated by central neural adaptations.     

Effects of diets of differing fiber contents on digestibility,passage rate of digesta and heat production in lesser mouse deer (Tragulus javanicus)

The effects of different levels of dietary fiber on feed intake, digestibility, mean retention times of solute and particle and heat production were studied in twelve male lesser mouse deer (Tragulus javanicus). The animals were randomly assigned into four groups of three mouse deer each and fed on individual basis. Four diets, namely A, B, C and D were prepared in pellet forms. Each diet contained ～14% crude protein and ～18 kJ/g gross energy. The crude fiber contents of diet A, B, C and D were 4.2, 11.3, 16.8 and 22.5%, respectively. The results showed that the crude fiber intake of mouse deer was 1.4 ± 0.04, 3.8 ± 0.4, 5.8 ± 0.7 and 6.0 ± 0.6 g/kg W^0.75/d fed diet A, B, C and D, respectively. Mouse deer fed diet D had significantly lower DM intake than those fed lower levels of fiber. The digestibility values of DM decreased gradually with increasing levels of fiber in the diet. The mean retention times (MRTs) of particles (～1.5 mm) in the reticulorumen were in the range of (19.0–22.9 h), with the shortest time for mouse deer fed diet D. However mouse deer fed diet C and D showed significant shorter solute MRT in the reticulorumen (17.1–18.5 h) when compared to mouse deer fed lower fiber diets (21.4–21.9 h). The selectivity factor in the reticulorumen was in the range of 1.04–1.18, indicating the mouse deer to be a ‘moose-type’ ruminant. Fiber levels had no significant effect on water intake of mouse deer. Heat production tended to decrease with increasing levels of fiber (448.3–435.7 kJ/kg W^0.75/d) but differences among the mouse deer fed the four diets were not significant.     

Advanced glycation end-products diminish tendon collagen fiber sliding

Connective tissue aging and diabetes related comorbidity are associated with compromised tissue function, increased susceptibility to injury, and reduced healing capacity. This has been partly attributed to collagen cross-linking by advanced glycation end-products (AGEs) that accumulate with both age and disease. While such cross-links are believed to alter the physical properties of collagen structures and tissue behavior, existing data relating AGEs to tendon mechanics is contradictory. In this study, we utilized a rat tail tendon model to quantify the micro-mechanical repercussion of AGEs at the collagen fiber-level. Individual tendon fascicles were incubated with methylglyoxal (MGO), a naturally occurring metabolite known to form AGEs. After incubation in MGO solution or buffer only, tendons were stretched on the stage of a multiphoton confocal microscope and individual collagen fiber stretch and relative fiber sliding were quantified. Treatment by MGO yielded increased fluorescence and elevated denaturation temperatures as found in normally aged tissue, confirming formation of AGEs and related cross-links. No apparent ultrastructural changes were noted in transmission electron micrographs of cross-linked fibrils. MGO treatment strongly reduced tissue stress relaxation (p < 0.01), with concomitantly increased tissue yield stress (p < 0.01) and ultimate failure stress (p = 0.036). MGO did not affect tangential modulus in the linear part of the stress–strain curve (p = 0.46). Microscopic analysis of collagen fiber kinematics yielded striking results, with MGO treatment drastically reducing fiber-sliding (p < 0.01) with a compensatory increase in fiber-stretch (p < 0.01). We thus conclude that the main mechanical effect of AGEs is a loss of tissue viscoelasticity driven by matrix-level loss of fiber–fiber sliding. This has potentially important implications to tissue damage accumulation, mechanically regulated cell signaling, and matrix remodeling. It further highlights the importance of assessing viscoelasticity – not only elastic response – when considering age-related changes in the tendon matrix and connective tissue in general.     

Effect of posterior cruciate ligament creep on muscular co-activation around knee: A pilot study

The effect of posterior cruciate ligament (PCL) on muscle co-activation (MCO) is not known though MCO has been extensively studied. The purpose of the study was to investigate the effect of PCL creep on MCO and on joint moment around the knee. Twelve males and twelve females volunteered for this study. PCL creep was estimated via tibial posterior displacement which was elicited by a 20 kg dumbbell hanged on horizontal shank near patella for 10 min. Electromyography activity from both rectus femoris and biceps femoris as well as muscle strength on the right thigh was recorded synchronically during knee isokinetic flexion–extension performance in speed of 60 deg/s as well as 120 deg/s on a dynamometer before and after PCL creep. A one-way ANOVA with repeated measures was used to evaluate the effect of creep, gender and speed. The results showed that significant tibial posterior displacement was found (p = 0.01) in both male and female groups. No significant increase of joint moment was found in flexion as well as in extension phase in both female and male groups. There was a significant effect of speed (p = 0.036) on joint moment in extension phase. Co-activation index (CI) decreased significantly (p = 0.049) in extension phase with a significant effect of gender (p ⩽ 0.001). It was concluded that creep developed in PCL due to static posterior load on the proximal tibia could significantly elicit the increase of the activation of agonist muscles but with no compensation from the antagonist in flexion as well as in extension phase. The creep significantly elicited the decrease of the antagonist–agonist CI in extension phase. MCO in females was reduced significantly in extension phase. It was suggested that PCL creep might be one of risk factors to the knee injury in sports activity.     

Braking characteristics during cutting and pivoting in female soccer players

Most biomechanical studies into changing direction focus on final contact (FC), whilst limited research has examined penultimate contact (PEN). The aim of this study was to explore the kinematic and kinetic differences between PEN and FC of cutting and pivoting in 22 female soccer players (mean ± SD; age: 21 ± 3.1 years, height: 1.68 ± 0.07 m, mass: 58.9 ± 7.3 kg). Furthermore, the study investigated whether horizontal force–time characteristics during PEN were related to peak knee abduction moments during FC. Three dimensional motion analyses of cutting and pivoting on the right leg were performed using Qualysis ‘Proreflex’ infrared cameras (240 Hz). Ground reaction forces (GRF) were collected from two AMTI force platforms (1200 Hz) to examine PEN and FC. Both manoeuvres involved significantly (P < 0.05) greater knee joint flexion angles, peak horizontal GRF, but lower average horizontal GRF during PEN compared to FC. Average horizontal GRF during PEN (R = −0.569, R² = 32%, P = 0.006) and average horizontal GRF ratio (R = 0.466, R² = 22%, P = 0.029) were significantly related to peak knee abduction moments during the FC of cutting and pivoting, respectively. The results indicate PEN during pre-planned changing direction helps reduce loading on the turning leg where there is greater risk of injuries to knee ligaments.     

The effects of irradiation dose and storage time following treatment on the viscoelastic properties of decellularised porcine super flexor tendon

Decellularised porcine super flexor tendon (pSFT) offers a promising solution to the replacement of damaged anterior cruciate ligament. It is desirable to package and terminally sterilise the acellular grafts to eliminate any possible harmful pathogens. However, irradiation techniques can damage the collagen structure and consequently reduce the mechanical properties. The aims of this study were to investigate the effects of irradiation sterilisation of varying dosages on the viscoelastic properties of the decellularised pSFT.Decellularised pSFT tendons were subjected to irradiation sterilisation using either 30 kGy gamma, 55 kGy gamma, 34 kGy E-beam, 15 kGy gamma, 15 kGy E-beam and (15 + 15) kGy E-beam (fractionated dose). Specimens then underwent stress relaxation testing at 0 and 12 months post sterilisation to determine whether any effect on the viscoelastic properties was progressive.Significant differences were found which demonstrated that all irradiation treatments had an effect on the time-independent and time-dependent viscoelastic properties of irradiated tendons compared to peracetic acid only treated controls. No significant differences were found between the irradiated groups and no significant differences were found between groups at 0 and 12 months. These results indicate the decellularised pSFT graft has a stable shelf-life.     

Differential regulation of extracellular matrix constituents in myocardial remodeling with and without heart failure following pressure overload

Patients with aortic stenosis develop various degrees of myocardial hypertrophy and heart failure (HF) despite comparable transvalvular gradients. An important element in the transition from compensated hypertrophy to HF is dilatation of the left ventricle (LV). The molecular pathology associated with LV dilatation and development of HF is not known. Thus, we examined potential differences in the regulation of myocardial extracellular matrix (ECM) constituents in mice with hypertrophy only (ABnonHF) and with HF (ABHF) as response to comparable pressure overload. The ascending aorta was banded, or left loose in sham-operated mice. Increased lung weight and left atrial diameter indicating pulmonary congestion were used to identify ABHF mice. Cardiac function and geometry were evaluated by echocardiography. Despite comparable pressure gradients and cardiac output, ABHF had reduced fractional shortening (23%), reduced systolic (28%) and diastolic (32%) tissue velocity and increased LV internal dimension in diastole (10%) and systole (17%) (LVIDd/s) compared to ABnonHF (p ≤ 0.05). Microarray analyses identified 120 differently regulated genes related to ECM in ABHF compared to ABnonHF (p ≤ 0.05). Interestingly, in ABHF, we found a 24% (p ≤ 0.05) reduction of the LV collagen VIII protein levels despite increased levels of LV total collagen by 23% (p ≤ 0.05). LV collagen VIII correlated negatively with LVIDd (R = 0.55, p = 0.03) and LVIDs (R = 0.72, p = 0.002). As this protein may function as a “sealant” binding collagen fibrils together, reduction of collagen VIII could potentially contribute to LV dilatation and development of HF.     

Heavy-intensity aerobic exercise affects the isokinetic torque and functional but not conventional hamstrings:quadriceps ratios

Running exercises are frequently related to muscular injuries, which may be a result of muscular imbalance. The present study aimed to verify the effects of heavy-intensity continuous running exercise on the functional and conventional hamstrings:quadriceps ratios, and also in the knee flexors and extensors EMG activity in active non-athletic individuals. Sixteen active males performed maximal isokinetic concentric and eccentric knee flexions and extensions at 60° s^?1 and 180° s^?1. In another session, the same procedure was conducted after a continuous running exercise at 95% onset of blood lactate accumulation. Torque and electromyographic ratios were calculated from peak torque and integrated electromyographic activity (knee flexor and extensors). Creatine kinase was measured before and 24 h after running exercise. Eccentric torque (knee flexion and extension) decreased significantly after running only at 180° s^?1 (p < 0.05). No differences were found for the conventional torque ratios (p > 0.05), however, the functional torque ratios at 180° s^?1 decreased significantly after running (p < 0.05). No effects on the electromyographic activity and electromyographic ratios were found (p > 0.05). Creatine kinase increased slightly 24 h after running (p < 0.05). Heavy-intensity continuous running exercise decreased knee flexor and extensor eccentric torque, and functional torque ratios under fast velocities (180° s^?1), probably as result of peripheral fatigue.     

Performance of rabbits on Guinea grass and Verano stylo hays in the dry season and effect of concentrate supplementation

The feasibility of using Verano stylo (Stylosanthes hamata cv. Verano) and Guinea grass (Panicum maximum cv. Ntchisi) hays and their replacement values in concentrate diets for rabbits were determined. The intake and growth of the rabbits were monitored over a 7-week growth study following a 2-week adaptation period, while nutrient digestibility was determined over a 5-day period during the eighth week of the study. The DM intakes of the rabbits during the growth study were 53.1 g/day of the grass + concentrate (50 : 50) diet, 56.0 g/day of the all-concentrate diet and 64.8 g/day for the Verano stylo + concentrate (50 : 50) diet. The respective weight gains were 5.13, 8.44 and 8.35 g/day. Lower DM intake and consistent losses in weight of the animals were recorded on Verano stylo or Guinea grass alone. Verano stylo hay was better than Guinea grass hay. Thus, concentrate supplementation of forage diets is necessary for rabbits. Replacement of 0.50 of the concentrate with Verano stylo hay gave a similar performance to that for the all-concentrate diet. It is, therefore, possible to reduce the use of concentrates in the diets for growing rabbits in the dry season by replacing part of the diet with Verano stylo hay.     

Kinematic and electromyographic analysis of the Nordic Hamstring Exercise

The Nordic Hamstring Exercise (NHE) has been introduced as a training tool to improve the efficiency of eccentric hamstring muscle contraction. The aim of this study was to perform a biomechanical analysis of the NHE. Eighteen participants (20.4 ± 1.9 years) performed two sets of five repetitions each of the NHE and maximal eccentric voluntary contraction (MEVC) of the knee flexors on an isokinetic dynamometer whilst knee angular displacement and electrical activity (EMG) of biceps femoris were measured. EMG was on average higher during the NHE (134.3% of the MEVC). During the forward fall of the NHE, the angle at which a sharp increase in downward velocity occurred varied between 47.9 and 80.5 deg, while the peak knee angular velocity (pVelocity) varied between 47.7 and 132.8 deg s^?1. A significant negative correlation was found between pVelocity and peak EMG (r = ?0.62, p < 0.01) and EMG at 45 deg (r = ?0.75, p < 0.01) expressed as a percentage of peak MEVC EMG. Some of the variables analyzed exhibited good to excellent levels of intra- and inter-session reliability. This type of analysis could be used to indirectly monitor the level of eccentric strength of the hamstring muscles while performing the NHE and potentially any training- or injury-related changes.     

Differences in the proportion of collagen and muscle in the canine lower urinary tract with regard to gonadal status and gender

Gonadectomy not only affects hormonal homeostasis but also alters the turnover of different components of the extracellular matrix in urogenital tissues. Collagen is an important component of the bladder and urethral walls and thus crucial for the mechanical properties of normal lower urinary tract (LUT) functions. This study aimed at investigating the possibility of differences in the proportion of collagen and muscle tissues in the LUT of intact and gonadectomised male and female dogs. Twenty clinically healthy dogs were used including 10 sexually intact dogs (5 males, 5 anoestrus females) and 10 gonadectomised dogs (4 males and 6 females). Four regions of the LUT, i.e. body and neck of the bladder as well as proximal and distal urethra were collected. The tissue sections were stained with Masson's Trichrome. Quantitative evaluation of the blue-stained area for collagen and red-counterstained area for muscle was performed using colour image analysis. The relative proportion of collagen and muscle significantly differed with the gonadal status, the gender and the region. Overall, gonadectomised dogs had a higher (P < 0.001) proportion of collagen and consequently a lower (P < 0.001) proportion of muscle than intact dogs. Regardless of gonadal statuses, females had a higher (P < 0.05) proportion of collagen and a lower (P < 0.05) proportion of muscle tissues than males. Gender differences were found in all four regions of the LUT in intact dogs but only in proximal urethra in gonadectomised dogs where spayed females had a higher (P < 0.05) proportion of collagen and less muscle (P < 0.05). Regional differences were observed in females; a higher proportion of collagen and therefore less muscle were found in the urethra compared with the bladder. Proportional differences in collagen and muscle between intact and gonadectomised animals suggest a relation of different hormonal statuses to structural changes in the canine LUT. Excessive collagen deposits and less muscular volume may impair structural and functional integrity of the LUT which may associate with the development of post-neutering urinary incontinence in the dog.     

Formulation of Pseudomonas chlororaphis strains for improved shelf life

Formulations of Pseudomonas strains with long-term shelf life are needed for commercial use in biological disease control and growth promotion in crops. In the present work Pseudomonas chlororaphis (Pc) 63-28 formulated with coconut fiber [moisture content (MC) of 80%], talc (MC 8%) or peat (MC 40%), with or without the addition of carboxymethylcellulose or xanthan gum, and formulations of Pc 63-28 and P. chlororaphis TX-1 in coconut fiber with water contents (v:v) of 75%, 45%, and 25%, were evaluated in terms of shelf life and cell viability. The shelf life of Pc 63-28 was longer when formulated in coconut fibre with a MC was 80% than in the other formulations and longer at 3 ± 1 °C compared to 22 ± 1 °C. Densities of viable Pc 63-28 cells in coconut fiber stored at 3 ± 1 °C did not decline significantly during 224 days when the MC was 80% and within 120 days at 75% MC. Densities of Pc TX-1 in coconut fiber of 75% MC did not decline within 60 days at 3 ± 1 °C. P. chlororaphis 63-28 survived longer in deionized water and buffer than in canola oil. Cells of Pc 63-28 cells formulated in coconut fibre of 80% MC after storage for 140 days at 3 ± 1 °C in coconut fiber improved hydroponic growth of hydroponic lettuce and better than cells freshly recovered from culture. We conclude that coconut fiber is a carrier of superior performance in maintaining shelf life of Pseudomonas strains. The observed shelf life would be sufficient for practical use of Pseudomonas strains as tools for disease control and growth promotion in crops.     

Differences in proprioception,muscle force control and comfort between conventional and new-generation knee and ankle orthoses

The aim of this study was to compare muscle force control and proprioception between conventional and new-generation experimental orthoses. Sixteen healthy subjects participated in a single-blind controlled trial in which two different types of orthosis were applied to the dominant knee or ankle, while the following variables were evaluated: muscle force control (accuracy), joint position sense, kinesthesia, static balance as well as subjective outcomes. The use of experimental orthoses resulted in better force accuracy during isometric knee extensions compared to conventional orthoses (P = 0.005). Moreover, the use of experimental orthoses resulted in better force accuracy during concentric (P = 0.010) and eccentric (P = 0.014) ankle plantar flexions and better knee joint kinesthesia in the flexed position (P = 0.004) compared to conventional orthoses. Subjective comfort (P < 0.001) and preference scores were higher with experimental orthoses compared to conventional ones. In conclusion, orthosis type affected static and dynamic muscle force control, kinesthesia, and perceived comfort in healthy subjects. New-generation experimental knee and ankle orthoses may thus be recommended for prophylactic joint bracing during physical activity and to improve the compliance for orthosis use, particularly in patients who require long-term bracing.     

Rabbit preference for cages and pens with or without mirrors

Five-week-old Pannon White rabbits were housed in a closed climatized rabbitry and randomly assigned to either pens (56 rabbits) having a basic area of 1 m² with a stocking density of 16 and 12 rabbits/m² or to 18 individual cages (0.24 m²/cage). The pens and the cages were divided into two halves and animals could move freely between the two halves through swing doors. The walls of one half of the pens and cages were completely covered with mirrors while the other half was covered with white plastic panels. A 24 h video recording was made twice a week using infrared cameras and the number of rabbits in each pen and cage was counted every 15 min. The duration of the trial was 6 weeks. The lighting period was 16L/8D. In each half of the cage or pen, a feeder and nipple drinkers were available and feed intake was measured separately. Throughout the entire rearing period, 72% of the individually caged rabbits showed a preference for the cage half enriched with mirrors (P < 0.001). This preference decreased slightly with increasing age. Preference toward the cage half provided with mirror walls was independent of the time of day; in other words, during the active period (23:00–05:00) corresponding to the dark part of the day, rabbits continued to prefer the mirrored half even if the vision of the reflected image was reduced. The presence of conspecifics at different stocking densities (12 vs. 16 rabbits/m²) did not reduce this interest in mirrors: averaging the ages, 66% of animals living at 16 rabbits/m² stocking density and 63% of those living at 12 rabbits/m² density were found in the half pen with mirrors (P < 0.001). Group-penned rabbits showed a marked preference toward mirrors during the active period (73–76% for 12 and 16 rabbits/m² stocking densities, respectively; P < 0.001). The results suggest that the presence of mirrors offers advantages perhaps related to comfort and welfare, and therefore might be used as environmental enrichment for fattening rabbits and advised for rabbits caged individually for long periods.