Biomedical subjects

A Barneveld

Publications and source records attributed to A Barneveld.

At least 73 records · Page 4Linked to original sources

PubMed1998

A microtiter plate assay for the determination of uronic acids.

The amount of uronic acid residues in samples containing glycosaminoglycans or pectin is an important parameter in the quantitative and structural analysis of these complex carbohydrates. This paper describes a method to determine the content of uronic acids in biological samples, using conventional polystyrene microtiter plates and microtiter plate-reading equipment with standard interference filters (i.e., 540 or 492 nm). This assay is a modification of a commonly used procedure, viz. hydrolysis of uronic acid containing carbohydrate polymers in 80% sulfuric acid containing tetraborate ions at 80 degrees C followed by a coloring step with an m-hydroxydiphenyl reagent at room temperature. The use of microtiter plates has several practical advantages: (i) less risk of handling hot, concentrated sulfuric acid is present; (ii) an accurate estimate of background absorbance by multiple reading of the plates is possible; and (iii) many samples can be assayed in one series without errors due to fading of the final color. The validity of the assay was checked for the quantification of hyaluronic acid in equine synovial fluid samples. We consider this the method of choice when a large number of samples must be analyzed for their content of uronic acid residues.

Animals↗

PubMed1998

Loading-induced changes in synovial fluid affect cartilage metabolism.

The purpose of this study was to determine whether changes in the synovial fluid (SF) induced by in vivo loading can induce an alteration in the metabolic activity of chondrocytes in vitro. Therefore, SF was collected from ponies after a period of box rest and after they had exercise for a week. Normal, unloaded articular cartilage explants were cultured in 20% solutions of these SFs for 4 days and chondrocyte activity was determined by glycosaminoglycan (GAG) turnover. In explants cultured in post-exercise SF, GAG synthesis was enhanced and GAG release was diminished when compared to cultures in pre-exercise SF. SF analysis showed that levels of insulin-like growth factors (IGF-I and IGF-II) tended to be higher in post-exercise SF, while no differences were found in metalloproteinase activity, hyaluronic acid and protein concentrations. This study showed that anabolic effects of joint loading on cartilage are, at least partially, mediated by alterations in the SF.

Animals↗

PubMed1998

Matrix metalloproteinase activity in equine synovial fluid: influence of age, osteoarthritis, and osteochondrosis.

OBJECTIVE: To investigate the influence of age, osteoarthritis (OA), and osteochondrosis (OC) on the matrix metalloproteinase (MMP) activity in the synovial fluid (SF) of equine joints. METHODS: SF was collected from normal and osteoarthritic metacarpophalangeal joints (normal: 14 adult, 28 juvenile; OA: 22 adult). And from normal and osteochondrotic tarsocrural joints (5 months: 11 normal, 8 OC; 11 months: 7 normal, 6 OC). Subsequently, overall MMP activity was measured. RESULTS: The level of active MMPs was almost twofold higher in SF from juvenile horses (age up to 11 months) than in SF from mature animals (4-30 years; p < 0.001). In juvenile horses MMP activity was higher in 5 month old foals than in 11 month old foals (p < 0.01). In adult horses MMP activity was independent of age. In OA joints the activity was nearly twice as high as in normal joints (p < 0.001). In OC joints MMP activity was not significantly different from normal, age matched, control joints. CONCLUSIONS: MMP activity in SF from normal adult joints is not related to age. In juvenile joints MMP activity is significantly higher than activity in joints from adult animals. It is hypothesised that the gradual decrease in MMP activity with increasing age reflects the declining metabolic activity resulting from ceasing growth and the accompanying decrease in cartilage remodelling. The increased MMP activity in osteoarthritis joints most likely reflects matrix destruction. In osteochondrosis MMP mediated matrix degradation appears not to be different from normal joints.

Age Factors↗

PubMed1998

Long-term consequences of experimental desmotomy of the accessory ligament of the deep digital flexor tendon in adult horses.

OBJECTIVE: To evaluate clinical and biomechanical consequences of desmotomy of the accessory ligament (AL) of the deep digital flexor tendon (DDFT) of equine forelimbs and determine whether this procedure is a viable treatment for chronic desmitis of the AL-DDFT. ANIMALS: 6 adult Standardbred trotters. PROCEDURE: Biomechanical recordings obtained before and 6 months after desmotomy were compared. Walk and trot joint angles, ground reaction forces, peak joint moments, and tendon forces were assessed. RESULTS: Within 10 days after surgery, all horses were sound at a trot. Swelling, increased carpal flexion in the terminal stance phase, and incidental stumbling at the beginning of exercise were observed. Flexion angle in the carpal joints was significantly increased at the end of the stance phase. Peak moments around the distal interphalangeal joint and forces in the DDFT and AL-DDFT were decreased. Metacarpophalangeal joint angles, peak metacarpophalangeal joint moments, and peak loading of the suspensory ligament and the superficial digital flexor tendon were unchanged. CONCLUSION: 6 months after desmotomy, AL-DDFT strain was reduced without causing changes in joint angles or increasing tendon loads or joint moments that could be considered hazardous for the horses. CLINICAL RELEVANCE: Changes in locomotion that remained 6 months after AL-DDFT desmotomy would be acceptable for horses with chronic desmitis if conservative treatment failed.

Animals↗

PubMed1998

Effects of experimental desmotomy on material properties and histomorphologic and ultrasonographic features of the accessory ligament of the deep digital flexor tendon in clinically normal horses.

OBJECTIVE: To evaluate posttrauma biomechanical behavior of the scar attributable to desmotomy of the accessory ligament of the deep digital flexor tendon (AL-DDFT), compared with the histomorphologic and ultrasonographic appearance. ANIMALS: 5 Standardbred trotters. PROCEDURE: Gross appearance, length, cross-sectional area (CSA), in vitro material properties, and ultrasonographic and histomorphologic features were studied 6 months after desmotomy. Tensile tests were conducted, with forces and elongation simultaneously recorded. Surgically treated limbs were compared with nontreated contralateral limbs. RESULTS: The CSA of the treated ligaments was increased threefold, and treated ligaments were 1 cm longer than control ligaments. In the healed AL-DDFT, stress and material stiffness were approximately a third of those values for controls. The functional characteristics, force and elongation at failure, reached 80% of control values. Ultrasonographic and the histomorphologic examination of the scar tissue revealed high amounts of randomly oriented collagen. CONCLUSION: From the ultrasonographic and histomorphologic findings and the material properties, it was concluded that the scar tissue was of inferior quality. However, the functional properties had been restored for the most part by increase of the CSA. The length increase may lead to strain relief in the AL-DDFT after desmotomy. CLINICAL RELEVANCE: Desmotomy is recommended as treatment for chronic desmitis.

Animals↗

PubMed1998

Experimental model of synovitis/capsulitis in the equine metacarpophalangeal joint.

OBJECTIVE: To develop and define a model of acute synovitis/capsulitis in the equine metacarpophalangeal joint (fetlock) to study clinical effects of diagnostic or therapeutic procedures. ANIMALS: 5 adult Standardbreds. PROCEDURE: Polyvinyl alcohol foam particles were injected into the left front fetlock of horses; the right front fetlock was used as a control. Horses were examined clinically and for lameness on a regular basis. Blood samples were taken to measure routine variables. Synovial fluid samples were collected from both fetlocks, and macroscopic, microscopic, and biochemical variables were measured. The effects of local diagnostic nerve blocks and intra-articular anesthesia of the fetlock on ensuing lameness were determined on days 2 and 3. After macroscopic evaluation at necropsy, histologic examination was performed on the fetlock cartilage and capsule. RESULTS: Changes in synovial fluid variables included increased TNF-alpha and matrix metalloproteinases values and in other indicators of acute inflammation. With respect to application of local nerve blocks, lameness decreased most after a combination of metacarpal and palmar nerve blocks, whereas lameness could only partially be blocked by intra-articular anesthesia. At necropsy, mild chronic inflammation of the synovium and deeper layers of the joint capsule was found; polyvinyl alcohol particles had been incorporated into the joint capsule. There was no evidence of articular cartilage damage. CONCLUSIONS: Injection of polyvinyl alcohol foam particles induces transient synovitis/capsulitis in the fetlock, mimicking clinical joint disorders. The model does not seriously affect the horse's long-term wellbeing. Such model serves well for studying the effect of diagnostic or therapeutic procedures.

Animals↗

PubMed1998

Innervation of the equine mature and immature proximal sesamoid bone by calcitonin gene-related peptide and substance P-containing nerves.

OBJECTIVE: To localize and determine relative frequency of occurrence of calcitonin gene-related peptide (CGRP) and substance P (SP) fibers in the proximal sesamoid bones (PSB) and adjacent structures in sound horses. SAMPLE POPULATION: 4 foals and 3 adult horses. PROCEDURE: Medial PSB and adjacent ligaments of both forelimbs were collected, flushed, and fixed in buffered 4% formalin. The left PSB were cut into 5 longitudinal, sagittally oriented slabs, and the right PSB were cut into 5 transverse slabs. After decalcification in EDTA, slices were transferred to a 30% sucrose solution, deep frozen, sectioned (80 microm), and stored in Tris-buffered saline solution for free-floating immunocytochemical processing, staining of which was performed by use of the peroxidase-antiperoxidase method with polyclonal rabbit antibodies against CGRP and SP. Sections were examined by light microscopy. RESULTS: Calcitonin gene-related peptide and SP fibers were present throughout the PSB; in ligaments, they were concentrated at the attachment sites. Presentation of the fibers, the innervation pattern, and intensity in the bones of horses differed from that in foals, in which the fibers were more delicate and frequency of occurrence was lower. In horses, innervation with CGRP and SP fibers was more dense in the periphery of the bone, whereas in foals, local difference in innervation of the bone was not evident. With the exception of the intersesamoidean ligament, ligaments were more richly innervated than was bone. CONCLUSION: Presence of the nociceptive peptides CGRP and SP indicated that the PSB and, more practically, the adjacent ligaments are sensitive structures.

Aging↗

PubMed1997

Influence of the force applied and its period of application on the outcome of the flexion test of the distal forelimb of the horse.

The influence of the force applied and its period of application on the outcome of the flexion test of the distal forelimb was investigated in a group of eight sound horses. The degree of lameness after the flexion test was scored by a standard clinical classification, and by measuring the angle of maximum fetlock extension by means of the infrared light-based MacReflex gait analysis system. There was a good correlation between the clinical score and this electronically recorded kinematic parameter (r = 0.96). Both the force applied and the period of application affected the outcome of the test. Increasing the force applied by 25 per cent led to three horses being judged positive, instead of two when the normal force was applied. Doubling the time to 120 seconds resulted in four horses rather than two being classified as lame after the test. Reducing the force to 75 per cent or the time to 30 seconds resulted in all the horses being classified as sound. A flexion test lasting five minutes, either at 100 per cent force or at 75 per cent, classified six of the eight horses as lame. It is concluded that the flexion test should be defined more precisely in terms of these two factors in order to make its results more consistent and hence more useful.

Animals↗

PubMed1997

Variations in the force applied to flexion tests of the distal limb of horses.

A pressure-sensitive device was developed to measure the force applied to flexion tests of the distal limb of horses. The mean force applied by a group of experienced clinicians was 150 N which results in a moment on the flexed fetlock joint of about 28.5 Nm. The coefficient of variation of the force applied by one experienced clinician was only about 12 per cent, but the coefficient of variation between clinicians was considerably higher (20 per cent), irrespective of whether the clinicians were considered to be experienced or not. The mean force applied by a group of women examiners (114 N) was significantly lower than that applied by the group of male examiners. It is concluded that the flexion test used in the clinical examination of the locomotor system of the horse should be better standardised.

Animals↗

PubMed1997

Inertial properties of Dutch Warmblood horses.

The complete set of three-dimensional inertial properties (mass, density, centre of mass, inertial tensor) was determined in 26 segments of six Dutch Warmblood horses. The measurements were performed with frozen segments similar to the procedure described by Lephart (1984, J. Biomechanics 17, 537-543). Based on these data linear regression models were developed for the estimation of inertial properties in living horses. The reproducibility of the dissection procedure was found to range between 2 and 9%. Both mean values and regression models are presented for all parameters. The mean standard error of estimation was 8% for the segment mass, 3% of the segment reference length for the position of the centre of mass, and 17% for the moments of inertia.

Animals↗

PubMed1997

Effects of treadmill inclination on kinematics of the trot in Dutch Warmblood horses.

To evaluate the effects of uphill trotting on stride characteristics, 6 well trained Dutch Warmblood horses trotted at 4 m/s on a horizontal and on an inclined (6%) treadmill. This was done under 3 different conditions, unloaded, mounted by an experienced 90 kg rider and loaded with 90 kg of lead, to study whether extra weight provoked more or different alterations than the incline per se. In all 3 test situations (unloaded, mounted and lead-loaded), heart rates were significantly higher on the inclined treadmill than on the horizontal treadmill. Stride duration tended to increase on the inclined treadmill. Stance duration increased significantly on a slope, more in the hindlimbs than in the forelimbs. In the unloaded condition, maximal fetlock extension of the forelimb decreased on the incline, whereas maximal fetlock extension of the hindlimb and tarsal range of motion increased significantly on the slope in all 3 conditions. The overall effect was that on an inclined treadmill the hindlimbs seemed to carry more weight (higher maximal fetlock extension), and to provide greater propulsion (higher tarsal flexion and increased pro/retraction).

Animals↗

PubMed1997

Kinematic comparison of the leading and trailing fore- and hindlimbs at the canter.

The canter is a 3 beat asymmetrical gait with a difference in timing between left and right limbs. To evaluate intralimb asymmetry at the canter, a group of 24 Dutch Warmbloods was evaluated on a treadmill (7 m/s) using a modified CODA-3 optoelectronic gait analysis system. Thirteen horses cantered in the left lead ('leading limb' group) and 11 in the right lead ('trailing limb' group) during left forelimb recordings, while 11 horses were at the left and 13 were at the right lead during left hindlimb recordings. Kinematic differences between horses from the 'leading limb' and 'trailing limb' group were statistically evaluated at a significance level of P<0.05. Stride, stance and swing duration were similar between the 2 groups. The pelvis rotation, angle of maximal protraction and total range of maximal pro- and retraction were larger in the 'leading limb' group, while the scapula rotation, and the angle of maximal retraction were larger in the 'trailing limb' group. The elbow and hip joints were more flexed at impact, at maximal extension and at maximal flexion of the leading limb, whereas the stifle joint was more extended at impact. Furthermore, the leading tarsal joint was more maximally flexed in stance and swing phase, whereas the carpal joint was more flexed only in the swing phase of the leading limb. However, during the stance phase the maximal fetlock extension of the trailing fore- and hindlimbs were significantly larger. Apparently, horses move at the canter with a more protracted leading limb by more flexing the elbow, carpal, hip and tarsal joints. In the trailing limb, however, the scapula is more rotated, and the tarsal and fetlock joints are more loaded. In conclusion, the difference in interlimb timing between left and right limbs at canter also leads to an asymmetry in intralimb coordination of these limbs.

Analysis of Variance↗

PubMed1997

Modeling study of compensatory head movements in lame horses.

OBJECTIVE: To study the role of head movements in lame horses. SAMPLE POPULATION: 11 Dutch Warmblood horses. PROCEDURE: A 2-segment 2-dimensional inverse dynamic model of trotting horses was developed: trunk and head/neck segment joined in a neck joint. Model input consisted of averaged segmental inertial properties and averaged kinematic data, taken from 11 horses, trotting on a treadmill (3.5 m/s) in 3 conditions of induced lameness: sound, mildly lame, and moderately lame. Dynamic and static effects were analyzed. RESULTS: Dynamic effects were found to be considerably larger than static effects. In the moderately lame condition, the maximal neck joint vertical force during the lame stance phase had a 27% decrease, compared with the sound situation. Neck joint sagittal torque and maximal vertical force on the trunk decreased by 31 and 13%, respectively. Load distribution between forelimb and hind limb indicated a relative load shift from the lame forelimb to the diagonal hind limb during the lame stance phase. The sound contralateral forelimb carried a higher load while the ipsilateral hind limb was unloaded. CONCLUSION: It could be concluded that asymmetric head movements have a major role in lameness compensation, which can be explained by inertial interaction between trunk and head/neck segment. Static effects, such as caudad shifting of the body center of mass, are of minor importance. CLINICAL RELEVANCE: This report clarifies the mechanism of lameness compensation and the method of lameness diagnosis.

Animals↗

PubMed1996

Side effects of oral antimicrobial agents in the horse: a comparison of pivampicillin and trimethoprim/sulphadiazine.

To evaluate the side effects of oral pivampicillin and trimethoprim/ sulphadiazine, 200 horses receiving these antimicrobial agents were studied. The horses received either trimethoprim/ sulphadiazine (30 mg/kg twice daily) or pivampicillin (25 mg/kg twice daily) for three or more days. No adverse effects other than loose faeces and diarrhoea were detected. The risk of diarrhoea was significantly less after the oral administration of pivampicillin (3 per cent) than after trimethoprim/ sulphadiazine (7 per cent). Horses whose appetite was reduced appeared to be predisposed to develop diarrhoea after the administration of either oral antimicrobial agent.

Administration, Oral↗

PubMed1996

Total replacement of the metatarsophalangeal joint in the horse. A single pilot study.

In this paper the successful replacement of an equine metatarsophalangeal joint by a human total condylar knee prosthesis is reported. In the period of observation following implantation of the endoprosthesis the experimental animal showed almost no lameness when exercised at walk, bearing weight on the operated limb. Flexion and extension of the joint were markedly reduced. The clinical and histological observations clearly support further investigation into the equine metatarsophalangeal joint replacement by an endoprosthesis.

Animals↗

PubMed1996

The arterial shift features in the equine proximal sesamoid bone.

Sesamoidosis in horses is characterised by lameness and radiographic changes in the proximal sesamoid bones and the aetiology is attributed to either mechanical factors or circulatory disturbances. In this study arteriograms of proximal sesamoid bones were investigated in 17 lame patients suffering from sesamoidosis, 6 sound horses and 4 yearlings. The arterial patterns of the proximal sesamoid bones from the patients, showed a shift from an abaxial to a basal arterial blood supply. This shift was only found in radiographically changed bones. Histological evaluation showed a significantly higher percentage of arteries with a large diameter in sections from the base of proximal sesamoid bones that showed an arterial shift. The presence of the shift appeared to be related to a change in shape of the bone, in particular to new bone formation along the abaxial border. The results of this study suggest that in horses suffering from sesamoidosis changes in the arterial pattern arise which might be a compensatory mechanism in respons to a vascular iischaemic challenge. Further investigations are needed to characterise the initial stimulus that induces this compensation and to determine if the compensation is sufficient to maintain a continuous and adequate blood supply.

Aging↗

PubMed1996

Distribution of penicillins into subcutaneous tissue chambers in ponies.

The distribution of penicillins into a tissue chamber implanted subcutaneously in ponies was studied. Ampicillin sodium (equivalent to 15 mg/kg ampicillin) was administered intravenously. Pivampicillin, a prodrug of ampicillin, was administered by nasogastric tube to fed ponies at a dose of 19.9 mg/kg (equivalent to 15 mg/kg ampicillin). Procaine penicillin G was administered intramuscularly at a dose of 12 mg/kg (equivalent to 12000 IU/kg). Six ponies were used for each medication. Antibiotic concentrations in plasma and tissue chamber fluid (TCF) were measured for 24 h after administration. Mean peak concentrations of ampicillin in TCF were 7.3 micrograms/mL, reached at 1.7 h, and 1.3 micrograms/mL, reached at 2.7 h, after administration of ampicillin sodium and pivampicillin respectively. The mean peak concentration of penicillin G of 0.3 microgram/mL was reached 12.3 h after administration of procaine penicillin G. Concentrations in TCF remained above the minimum inhibitory concentration of Streptococcus zooepidemicus for the proposed dosing intervals of 8, 12 and 24 h for ampicillin sodium, pivampicillin and procaine penicillin G respectively.

Ampicillin↗

PubMed1996

Clinical efficacy of ampicillin, pivampicillin and procaine penicillin G in a soft tissue infection model in ponies.

Tissue chambers, implanted subcutaneously in ponies, were inoculated with Streptococcus zooepidemicus. The animals received either no antibiotics or one of the following treatments: pivampicillin per os (19.9 mg/kg, equivalent to 15 mg/kg ampicillin, every 12 h) for 7 or 21 days (7 and 5 ponies, respectively), procaine penicillin G intramuscularly (12 mg/kg = 12,000 IU/kg, every 24 h) for 7 days (7 ponies), or ampicillin sodium intravenously (equivalent to 15 mg/ kg ampicillin, every 8 h) for 1 day (5 ponies). Only intravenous administration was started before infection (prophylactically), the other treatments were started 20 h after infection (curatively). A total of 7 ponies received no antibiotics. In untreated controls, the infection led to abscessation of the tissue chamber in 4 to 10 days. Curative treatment with either pivampicillin or procaine penicillin G for 7 days resulted in a reduction of viable bacteria in the tissue chamber but did not eliminate the infection, resulting in abscessation in 5 to 14 days. However, administration of pivampicillin for 21 days eliminated the streptococci in five out of five ponies and prophylactic administration of ampicillin was successful in three out of five ponies.

Ampicillin↗