Collagenase-1 (MMP-1) activity in equine synovial fluid: influence of age, joint pathology, exercise and repeated arthrocentesis

REASONS FOR PERFORMING STUDY: Matrix metalloproteinases (MMPs) are considered candidate biomarkers for both physiological and pathological tissue remodelling because of their key role in articular cartilage homeostasis. As disruption of the collagenous architecture is thought to be pivotal in chronic degenerative diseases such as osteoarthritis (OA), the collagenases form an interesting subset of the MMPs. The significance of any biomarker in synovial fluid (SF) can be assessed properly only when fluctuations in patterns induced by physiological processes such as development and growth, and by external influences and interventions such as exercise and repeated arthrocentesis, are known and taken into account. OBJECTIVES: To investigate the activity of MMP-1 in equine SF at different stages of development and in joints affected by OA, and the influence of exercise and repeated arthrocentesis thereon. METHODS: MMP-1 activity was determined in SF of normal joints of fetal, juvenile and mature horses, and in SF of horses suffering from OA, using an internally quenched fluorogenic peptide substrate. MMP-1 activity was also measured in SF from horses subjected to an exercise regimen and those subjected to repeated arthrocentesis. RESULTS: An age-related decline in the SF levels of active MMP-1 was observed. MMP-1 activity was 15-fold higher in fetal than in juvenile animals, which showed significantly higher MMP-1 activity levels than mature horses. In SF of OA joints, MMP-1 activity was increased. Exercise did not affect MMP-1 activity in SF, but repeated arthrocentesis (within 60 h) increased MMP-1 activity significantly. CONCLUSIONS: The high MMP-1 activity in SF of young individuals parallels the high metabolic activity occurring during rapid growth and differentiation at early age. The elevated MMP-1 activity in SF of OA joints probably reflects pathological matrix degradation, confirming the potential of MMP-1 to serve as a biochemical marker for early joint disease. Moderate exercise is not likely to influence the outcome of MMP-1 activity measurements in equine SF, but arthrocentesis should be taken into account as a possible confounding factor. POTENTIAL RELEVANCE: Given the crucial role of the collagen matrix for tissue integrity, MMP-1 activity may be a useful tool in diagnostic, therapeutic or prognostic studies in horses suspected of OA. However, care should be taken to exclude fluctuations in MMP-1 activity induced by physiological processes such as development and growth, and by interventions such as repeated arthrocentesis.     

The influence of repeated arthrocentesis and exercise on matrix metalloproteinase and tumour necrosis factor alpha activities in normal equine joints

REASONS FOR PERFORMING STUDY: Matrix metalloproteinases (MMPs) and tumour necrosis factor alpha (TNF-alpha) may be useful as biomarkers of joint disease or inflammation. However, activity of both MMPs and TNF-alpha in synovial fluid (SF) may be influenced by nonpathological factors such as arthrocentesis or exercise. OBJECTIVE: To investigate the influence of repeated arthrocentesis and exercise on MMP and TNF-alpha activities in SF from normal equine joints. METHODS: SF was collected from the left metacarpophalangeal, radiocarpal and tarsocrural joints of 16 horses. Eight of these horses were subsequently subjected to an exercise programme on a treadmill and 8 were box-rested as controls. Arthrocentesis was repeated 14, 145, 17 and 24 days after the start of the exercise programme. General MMP and TNF-alpha activities were determined in SF. RESULTS: Repeated arthrocentesis caused a gradual increase but the exercise regimen no significant increase in MMP activity. There was a significant increase in TNF-alpha activity in SF collected from horses 2 h after cessation of the exercise programme. CONCLUSIONS AND POTENTIAL RELEVANCE: When using MMPs as biomarkers for joint disease, at least 14 days should elapse after previous arthrocentesis before subsequent SF collection. Moderate exercise does not increase MMP activity in SF from normal joints and it may be possible to ignore this as a source of error in evaluating MMP activity in diseased joints.     

Reciprocal rewards stabilize cooperation in the mycorrhizal symbiosis

Plants and their arbuscular mycorrhizal fungal symbionts interact in complex underground networks involving multiple partners. This increases the potential for exploitation and defection by individuals, raising the question of how partners maintain a fair, two-way transfer of resources. We manipulated cooperation in plants and fungal partners to show that plants can detect, discriminate, and reward the best fungal partners with more carbohydrates. In turn, their fungal partners enforce cooperation by increasing nutrient transfer only to those roots providing more carbohydrates. On the basis of these observations we conclude that, unlike many other mutualisms, the symbiont cannot be "enslaved." Rather, the mutualism is evolutionarily stable because control is bidirectional, and partners offering the best rate of exchange are rewarded.     

Effect of osmolality on net fluid absorption in non-infected and ETEC-infected piglet small intestinal segments

In the small intestinal segment perfusion model the effect of osmolality on net fluid absorption in enterotoxigenic Escherichia coli (ETEC)-infected and non-infected small intestinal segments of piglets was investigated. In ETEC-infected segments net fluid absorption was reduced. Lowering the osmolality from 375 to 150 mOsmol/l by reducing sodium chloride concentrations increased net fluid absorption. There was a linear relationship between osmolality and net fluid absorption for both non-infected and ETEC-infected segments. Below 150 mOsmol/l the inverse relationship between osmolality and net fluid absorption disappeared. Substitution of sodium chloride with mannitol decreased net fluid absorption since mannitol cannot be actively absorbed. In ETEC-infected segments perfused with oral rehydration solution net fluid absorption significantly increased compared to a sodium chloride solution of similar osmolality, probably because of the high glucose concentration. Supplying hypotonic sodium chloride fluids to piglets can be beneficial in replenishing water and electrolyte losses in case of infectious diarrhoea.     

Intravenous vitamin K1 normalises prothrombin time in 1 hour in dogs with anticoagulant rodenticide toxicosis

Four dogs with anticoagulant rodenticide toxicosis were treated with intravenous vitamin K₁ in lieu of plasma transfusion due to client cost constraints. Two dogs experienced a suspected anaphylactoid reaction, necessitating cessation of the treatment in one dog. Prothrombin time was rechecked 1 h after treatment in the remaining three dogs and all results were within the normal reference range. All four dogs were discharged from hospital within 48 h of presentation. Intravenous vitamin K₁ rapidly reverses the coagulopathic state in dogs with anticoagulant rodenticide toxicosis. It is a viable alternative therapy to plasma transfusion if circumstances preclude its use; however, patients must be monitored for anaphylactoid reactions.     

Postnatal Changes in Testicular Concentrations of Transforming Growth Factors‐Alpha and‐Beta 1, 2 and 3 and Serum Concentrations of Insulin Like Growth Factor I in Bulls

Based on work largely in laboratory animals, transforming growth factors (TGF) and insulin like growth factors (IGF) could be regulators of testicular development. The aim of this study was to see if TGF‐alpha and ‐beta 1, 2 and 3 are present in the bovine testis and to monitor concentrations of these factors in the testis and IGF‐I in serum during reproductive development. Separate groups of Hereford × Charolais calves (n = 6) were castrated every 4 weeks from 5 to 33 weeks of age and at 56 weeks of age. A week prior to castration, from 5 to 33 weeks of age, blood was collected every 15 min for 10 h. Serum IGF‐I concentrations increased from 8 to 12 weeks of age, decreased from 24 to 28 weeks and increased to 32 weeks of age (p < 0.05). Testicular TGF‐alpha concentrations increased from 13 to 17 weeks of age, decreased to 21 weeks and from 33 to 56 weeks of age (p < 0.05). Testicular TGF‐beta 1 concentrations decreased from 17 to 21 weeks of age, increased to 25 weeks and decreased from 25 to 33 weeks of age (p < 0.05). Testicular TGF‐beta 2 concentrations increased from 5 to 17 weeks of age, decreased to 21 weeks, increased to 25 weeks and decreased at 29 weeks of age (p < 0.05). Testicular TGF‐beta 3 concentrations increased from 13 to 17 weeks of age, decreased to 21 weeks and from 25 to 29 weeks of age (p < 0.05). We concluded that TGF‐alpha and TGF‐beta 1, 2 and 3 are present in the testis of the bull calf, and changes in concentrations with age suggest a functional role in the development of the testis.     

The Effect of Parity of the Dam on Sexual Maturation,Serum Concentrations of Metabolic Hormones and the Response to Luteinizing Hormone Releasing Hormone in Bull Calves

The objectives of this study were to determine the effect of parity of the dam on age at which a scrotal circumference (SC) ≥ 28 cm was attained and the LH response to Luteinizing Hormone Releasing Hormone (LHRH) in bull calves. We also wanted to confirm, in a large group of bull calves, that the LH response to LHRH could be used to select early maturing bulls. Body weight and SC of the bull calves were measured every other week. At 15, 20 and 25 weeks of age, calves received 4.12 nm /kg body weight of LHRH ischio‐rectally and blood samples were taken every 15 min for 4 h. Calves from primiparous and multiparous dams were separated into two sub‐groups based on age at which an SC ≥ 28 cm was attained (early or late). An SC ≥ 28 cm was attained earlier in calves born to multiparous as compared with primiparous dams (p < 0.05). At 20 and 25 weeks of age, peak serum LH concentrations (LH‐peak) and area under the LH response curve (LH‐AUC) in response to LHRH were higher (p < 0.01) in calves born to multiparous as compared with primiparous dams. In calves born to multiparous dams the LH‐peak at 15 and 25 weeks of age and the LH‐AUC at 15 weeks of age were lower (p < 0.05) in calves that attained an SC ≥ 28 cm early as compared with late. The LHRH‐challenge test sensitivity and specificity ranged from 46% to 86%. We concluded that parity of the dam affected age at which SC ≥ 28 cm was attained and the LH response to LHRH in bull calves. Serum LH responses to LHRH at 15 and 25 weeks of age, in calves born to multiparous dams, show some promise for development into a test to select early maturing bull calves.     

Post‐natal Changes in Testicular Concentrations of Interleukin‐1 Alpha and Beta and Interleukin‐6 during Sexual Maturation in Bulls

Based on observations in laboratory animals interleukins could be regulators of testicular development. The objects of this study were to see if interleukins (IL‐1 and IL‐6) are present in the developing bull testis and to establish the temporal patterns of concentrations of IL‐1 and IL‐6 in the bovine testis during development. Separate groups of six bull calves were castrated every 4 weeks from 5 to 33 weeks of age, and at 56 weeks of age. Mean testicular IL‐1 alpha concentrations decreased (p < 0.01) from 5 to 9 weeks of age and 13 to 21 weeks of age. Mean testicular IL‐1 beta concentrations decreased (p < 0.01) from 13 to 17 weeks of age and from 29 to 33 weeks of age. Mean IL‐1 bioactivity increased from 13 to 17 weeks of age, decreased to 21 weeks, increased to 25 weeks, decreased to 29 weeks and decreased from 33 to 56 weeks of age (p < 0.05). Mean testicular IL‐6 concentrations decreased (p < 0.05) from 9 to 13 weeks of age, increased (p < 0.05) to 21 weeks, decreased (p < 0.05) to 25 weeks, increased (p < 0.05) to 29 weeks and decreased (p < 0.01) to 56 weeks of age. In conclusion, testicular IL‐1 alpha, IL‐1 beta and IL‐6 were found in the bovine testis and concentrations were age dependent. Testicular IL‐1 alpha and IL‐1 beta concentrations were highest in the early post‐natal period; however, IL‐1 bioactivity and IL‐6 concentrations were greatest in the immediate pre‐pubertal period. These findings suggest a functional role for interleukins in testicular development in the bull.