Biomedical subjects

W Back

Publications and source records attributed to W Back.

At least 37 records · Page 2Linked to original sources

PubMed2004

The effect of preventive trimming on weight bearing and force balance on the claws of dairy cattle.

Claw disorders and lameness in dairy cattle are an increasing problem of the modern dairy industry. To prevent claw disorders from evolving from the subclinical to the clinical stage, trimming is the management practice most routinely applied. The goal of preventive trimming (Toussaint-Raven method) is to promote natural loading by increasing the weight-bearing contact area of the claws and improving the balance between the medial and lateral claw. The biomechanical effect of preventive claw trimming was investigated with the aid of pressure distribution and ground reaction force recordings of the standing cow sampled simultaneously at 250 Hz. It appeared that preventive trimming of the hind limbs (n = 10) brought the claws slightly more in balance. Before trimming, 80% of the total force is taken up by the lateral claw and 20% by the medial claw. After trimming, this becomes 70 to 30%, respectively. Thereby, a significant increase in the weight-bearing contact area from 27.5 to 40.0 cm2 was achieved, resulting in a significant decrease in average pressure. However, the claws remained subjected to unaltered, high maximum pressures after trimming. The suggestion was made that the main focus of claw trimming should not be force balance; instead, a reduction of local maximum pressures at the contact area should be targeted in such a way that the strongest parts of the claw capsule (i.e., the wall) will be subjected to the highest pressures.

Animal Husbandry↗

PubMed2003

[Malignant melanoma of the pelvis as a possible cause of pelvic limb lameness in two gray mares].

Two grey mares, a 12-year-old Arabian and a 13-year-old Lippizaner cross, were referred for chronic pelvic limb lameness and abduction of the limb during the non supporting phase of the stride. The clinical examination revealed melanomas under the tail and on the perineum, and oedema of the proximal lame limb. A mass in the pelvic area was detected on rectal palpation. Laparoscopy was performed and the provisional diagnosis of malignant melanoma was made. Histological examination of the biopsy taken under laparoscopic control from the mass in the pelvis confirmed the diagnosis of malignant melanoma. In the postmortem examination a large black mass in the pelvis and metastases in several organs were diagnosed. The process under the tail showed microscopically the characteristics of dermal melanomatosis. The metastases showed the appearance of a malignant melanoma. The lameness and abduction during the non supporting phase of the stride were possibly caused by a combination of pain, a mechanical limitation, and paresis/paralysis. When an older grey horse with melanomas on the predilection sites is submitted with pelvic limb lameness and abduction of the limb during the non supporting phase of the stride, a malignant melanoma in the pelvis is one of the differential diagnoses and a rectal examination should be performed. Diagnostic laparoscopy in the standing horse can be useful to confirm the provisional diagnosis.

Animals↗

PubMed2003

[Splenectomy in a dressage pony: end of sports career?].

A 14-year-old Arabian cross-bred gelding was referred to the University Clinic because of mild, recurrent signs of colic for 5 days. The pony showed icteric mucous membranes, haemolytic blood, and dark coloured urine. Internal examination did not give a clear diagnosis. Unidentified intra-abdominal strands were found and haemorrhagic abdominocentesis led to the decision to perform an exploratory laparatomy. An extremely enlarged spleen was the sole finding. A splenal biopsy sample was taken and surgery was completed. The pony remained colicky, so the spleen was examined by ultrasonography. After this examination, the tentative diagnosis 'tumour of the spleen' was made and splenectomy was performed. Pathological examination of the spleen revealed splenomegaly caused by infarctions of unknown origin. Eight weeks after surgery, the pony started again in dressage competition. Six months after splenectomy, the pony won the provincial dressage competition.

Animals↗

PubMed2003

Effect of lateral heel wedges on sagittal and transverse plane kinematics of trotting Shetland ponies and the influence of feeding and training regimes.

REASONS FOR PERFORMING STUDY: Lateral heel wedges are used to treat horses and ponies with patella fixation or bone spavin. However, these therapies are purely empirically based and lack scientific evidence. OBJECTIVES: Lateral heel wedges would change joint motion in the sagittal, but mainly in the transversal planes, in healthy horses. This effect would be increased by restricted feeding and decreased by extra training. METHODS: A group of 24 Shetland ponies age 3 years was used, as foals had been assigned to restricted and ad libitum (ad lib) feeding, and low and high level training groups of 6 animals each. An experienced judge evaluated passive patella luxation in the square standing pony, using a score of 0 (normal) to 4 (stationary patella luxation). The motion of the markers, glued to the skin covering skeletal landmarks on the left fore- and hindlimbs, was recorded 3 dimensionally at a frequency of 300 Hz using a modified CODA-3 apparatus while trotting on a treadmill at a speed of 3.0 m/sec, before and directly after 5 degrees lateral heel wedges had been applied to the hindlimbs. After data analysis, the kinematic variables in the sagittal and transversal plane, under these 3 conditions (wedge, feeding, training), were compared statistically using a multivariate repeated measures analysis, general linear model (P < 0.05). RESULTS: In the sagittal plane, an acute change in hind hoof conformation resulted in a less animated trot with a less protracted forelimb and less hindlimb flexion. This is similar, although less pronounced, to the decrease in limb flexion reported previously as a result of restricted feeding. More specifically, lateral heel wedges resulted in significant changes in the transversal plane angles of all joints in the hindlimb. The stifle joint became maximally 1.8 degrees more adducted just before the end of the stance phase, while the tarsal joint was 2.9 degrees and fetlock joint 4.7 degrees more abducted (P < 0.05). In the restricted feeding group, stifle joint adduction was 85 degrees and tarsal joint abduction 5.6 degrees larger than in the ad libitum feeding group (P < 0.05). The patella luxation score was also significantly higher in this group (1.8) compared to ponies fed ad libitum (0.9). CONCLUSIONS: The acute effects of lateral heel wedges on the equine locomotor system in the transversal plane movement relieve tension from the medial patellar ligament and decrease pressure on the medial side of the tarsal joint. However, the fetlock joint experiences considerably more out of plane stress. Poor body condition resulted in a 2x worse patella luxation score, while the effect on stifle and tarsal joint movement in the transversal plane was almost 5x and 2x larger, respectively, than a lateral wedge. POTENTIAL RELEVANCE: The clinical importance of general body condition for maintaining lateral stability in the equine hindlimbs is established, but future research may prove that wedges are beneficial to treat patella fixation and bone spavin in the long term.

Animals↗

PubMed2003

The vertical ground reaction force and the pressure distribution on the claws of dairy cows while walking on a flat substrate.

The pressure distribution under the bovine claw while walking was measured to test the hypotheses that the vertical ground reaction force is unevenly distributed and makes some (regions of the) claws more prone to injuries due to overloading than others. Each limb of nine recently trimmed Holstein Friesian cows was measured five times while walking over a Footscan pressure plate firmly embedded on a Kistler force plate. The pressure plate had a spatial resolution of 2.6 sensors/cm2 and was sampled simultaneously with the force plate with a temporal resolution of 250 measurements/s. Five moments during the stance phase were selected on basis of the force plate recording for the analysis of the pressure distribution: heel strike, maximum braking, midstance, maximum propulsion, and push off. At the forelimbs, the vertical ground reaction force was equally distributed between medial and lateral claw. At the hind limbs at heel strike, the force was exerted almost completely to the lateral claw. During the rest of the stance phase the load shifted towards the medial claw, until, at push off, it was more or less equally divided between both claws. The average pressures determined were 50 to 80 N/cm2. Maximum pressures increased from 90 to 110 N/cm2 at heel strike to 180 to 200 N/cm2 at push off. It was concluded that at the hind limb these pressures constitute a major threat to overloading particularly for the softer parts of the lateral claw, e.g., the sole and bulb area.

Animals↗

PubMed2002

Auer rod-like inclusions in multiple myeloma.

We report a case of IgA multiple myeloma, in which the plasma cells showed multiple azurophilic, Auer rod-like intracytoplasmic inclusions in May-Grünwald-Giemsa-stained marrow smears. Cytochemical stainings revealed a strong alpha-N-esterase activity of these inclusions, whereas the reactions for peroxidase, Sudan black, chloroacetate esterase, and PAS were negative. Immunostaining verified IgA-kappa inside the plasma cells. The inclusions, however, were negative. Amyloid and lysozyme were also not detectable. Electron microscopy showed Auer rod-like inclusions with a smooth surface in the neighborhood of a well-developed rough endoplasmic reticulum, but with no direct relation to it. The inclusions showed a fine lamellar substructure, and the periodicity of the filamentous striations was about 10 nm, comparable with the substructure of typical Auer rods. Our findings suggest that the azurophilic inclusions in multiple myeloma are Auer rod-related structures, which likewise consist of active lysosomal enzymes. In contrast to the Auer rods in acute myeloblastic leukemia (AML), however, the inclusions in multiple myeloma consist of typical plasma cell enzymes.

Azure Stains↗

PubMed2002

[The effect of a treatment protocol on the prognosis of equine laminitis].

All horses and ponies with laminitis treated at the Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, between 1995 and 1998 were analysed retrospectively (n = 152). Based on the results of this study and on the world-wide knowledge on laminitis a standardised treatment protocol was adopted in 1999. Fifty-eight patients have been treated for laminitis between 1999 and 2001 following the treatment protocol. Compared to our hospital-population (orthopaedic patients), mares and ponies are at higher risk developing laminitis, but the prognosis does not differ between sexes as between breeds. Radiological evidence of rotation of the third phalanx seems to be of minor importance for the prognosis. Distal displacement of the third phalanx, however, seems to worsen the prognosis. The outcome of the acute cases is significantly better in the group treated following the protocol, than in the group without protocol. The outcome of the chronic cases is not influenced by the treatment protocol. Although the cases in both groups differ, as they are all clinical cases, our data suggest that the standardised treatment protocol results in a better outcome for cases of acute laminitis.

Acute Disease↗

PubMed2002

Jumping characteristics of naïve foals: lead changes and description of temporal and linear parameters.

The selection of foals as future showjumpers remains a subjective process based on qualitative parameters; and hence, frequently suffers from disparity in the criteria used by experts in the field. A detailed biomechanical description of foals while jumping would be most helpful in providing a better basis for the accurate assessment of their future athletic ability. The Qualisys Pro Reflex system was used to capture 3-dimensional kinematics of 41 Dutch Warmblood foals age 6 months free jumping a vertical fence, preceded by a cross pole fence. The left lead was the most preferred lead for both the fore- and hindlimbs, from the landing following the cross poles to the first move-off stride after clearing the vertical fence. The foals displayed a high incidence of rotary gallop during both the jump stride (divided into take-off, jump suspension and landing) and the first move-off stride, while change of lead was frequently observed during jump suspension. At the take-off side of the fence, the trailing forelimb in the last approach stride was placed furthest from the fence, whereas the trailing hindlimb at take-off was placed closest (P<0.05). At the landing side, the trailing forelimb was the closest and the leading hindlimb of the move-off stride 1 was the furthest (P<0.05). The trailing forelimb in the approach stride 1 had a significantly longer stance phase duration than the leading forelimb. At landing, the leading forelimb stance phase lasted longer than that of the trailing forelimb (P<0.05). The hindlimbs did not differ in their stance phase duration at take-off. The height reached by the hooves above the fence top was significantly greater in the hind limbs (P<0.05). In addition, the hindlimbs (97.1 +/- 2.6%) shortened more than the forelimbs (92.6 +/- 5.7%) (P<0.05). It is concluded that the overall jumping technique of foals is similar to that reported in literature for mature horses. If the patterns are consistent throughout the rearing period, the quantitative analysis of the kinematics of free jumping foals may provide a valid quantitative basis for early selection.

Animals↗

PubMed2002

Comparison of VHS video recording system with apple Macintosh-based image analysis and modified CODA-3 systems in equine motion analysis.

A VHS video--computer-based image analysis combination is described as a low sampling rate motion analysis system. Video recordings were taken indoor without any artificial illumination at 25 fps sampling rate. The horse studied was running on a high-speed treadmill and observed at 1.6, 4 and 7 m/s velocities at walk, trot and canter, respectively. Left forelimb and hindlimb were recorded separately from lateral view. For comparison, parallel CODA-3 recordings were taken at the same time from the same position. Joint angles were expressed and compared in angle-time diagrams. Sampling of both systems has been synchronised by a timer device at +/- 1/300 s error level. Results obtained with the two different recording systems were comparable in all joints measured with the exception of the fetlock. Inaccuracies in fetlock recordings are thought to be eliminated by measuring at controlled illumination. As a conclusion, the VHS-Macintosh setup appears to be promising as a simplified system for gait analysis.

Animals↗

PubMed2002

Longitudinal development of kinematics in shetland ponies and the influence of feeding and training regimes.

Nowadays, ponies are used more and more for competitive equine sports, driving and racing. The locomotor performance of ponies, however, has been evaluated in only a few kinematic and kinetic studies. To compare the longitudinal development of locomotor characteristics in the pony to the same process in the horse, the kinematics of 23 Shetland ponies were recorded at the trot on a treadmill (3 m/s) at ages 4 and 30 months using a modified CODA-3 apparatus. Furthermore, the influence of specific feeding and training regimes on this development was evaluated. It appeared that stride and stance duration increased with age, but the swing duration and pro/retraction range were similar at foal and mature age. Fore- and hindlimb maximal joint flexion at swing was larger in the mature ponies compared to foals. The elbow and shoulder joint were kept in a more extended position and the stifle joint more flexed, while scapula and pelvis were kept in a more vertical position. These effects are similar to those found in horses. The majority of both temporal and angular kinematic variables correlated significantly between foals and mature ponies. Ponies that were restricted in their feeding, resulting in a low body condition score, demonstrated a flatter gait than ponies fed ad lib (4 cm more height, 60 kg more weight), which trotted at the same velocity with significantly more joint flexion. Extra sprint training on top of free paddock exercise did not significantly influence the longitudinal development of kinematics. From these data, it can be concluded that the longitudinal development of locomotor characteristics in ponies is similar to that in horses. Fatter animals show a more animated gait, while extra sprint training added to free paddock exercise has no detectable effect on the development of kinematics. Aside from training or feeding regimes, in the Shetland pony breed, it appears possible to recognise 'good movers' at a young age.

Age Factors↗

PubMed2002

The pressure distribution under the bovine claw during square standing on a flat substrate.

The distribution pattern of pressure over the bovine claw was investigated to test the hypothesis that the ground reaction force is unevenly distributed and makes some regions of the claw more prone to overloading and injury than others. In eight recently trimmed Holstein Friesian cows, the distribution of vertical pressure was measured during square standing with a spatial resolution of 2.6 sensors/cm2 and a temporal resolution of 313 measurements/s. In each animal, the localization of maximum pressure per foot and per claw was determined during five trials. In the front limb, maximum pressures were normally found on the medial claw; in the hindlimb they were located on the lateral claw. In both claws, the highest pressures were found on the sole of the foot and not on the wall. In the front limbs, maximum pressures were located in the posterior portion of the sole; in the hind limb in the anterior portion. There was no difference in the location of the maximum pressure between the medial and lateral claw in either limb. The regions in which these maximum pressures occur are known to be relatively susceptible to injuries. This could indicate a causal relation between the location of pressure concentrations and claw diseases found in clinical observations.

Animal Husbandry↗

PubMed2001

[Follicular dendritic reticulum cell sarcoma in a cervical lymph node].

Follicular dendritic cells (FDC) constitute an essential component of B cell follicles, normally serving as antigen-presenting cells and as cells regulating the germinal center reaction. FDC sarcoma is a very rare tumor. We report the case of a 55-year-old male patient who showed persistent cervical lymph node swelling. On biopsy the tumor consisted of spindle cells with nuclear atypia. Immunophenotypic investigation of the tumor tissue revealed a FDC sarcoma of a cervical lymph node. The tumor cells were characterized immunohistochemically especially by the expression of CD21 and focal expression of CD68. In conclusion, FDC sarcoma has to be considered in cases of tumors of uncertain origin in cervical lymph nodes, tonsils, soft palate, or nasopharynx. For clinical practice, it is important to note that sarcomas in cervical lymph nodes are not necessarily metastases but can be primary tumors.

Biopsy↗

PubMed2001

Effects of 'navicular' shoeing on equine distal forelimb kinematics on different track surface.

Orthopaedic shoeing applied for disorders such as navicular disease is mostly evaluated on hard track surfaces, but very often horses are ridden only on soft tracks. To compare the effects of normal shoes, eggbar shoes, and shoes with heel wedges (5 degrees) on the kinematics of the distal forelimb on hard and soft track surfaces, eleven sound Dutch Warmblood horses were led across three different tracks (an asphalt, a fibre/sand mix (= Agterberg), and a pure sand track) with three different shoe types (a normal shoe, an eggbar shoe, and a shoe with heel wedges). The hoof rotation and the maximal extension of the fetlock joint at midstance period were recorded by an infrared-light based gait analysis system (ProReflex) at walk and at trot. Statistical analysis revealed significant effects of track and shoe type, and a shoe-track interaction (p<0.05). On soft track surfaces, the equilibrium of the distal forelimb dictated a 1.5-4 degrees forward rotation of the normal or eggbar shod foot, the most on a sand track. The wedge effect on hoof rotation, however, was always significantly greater, but similar to that on the hard track surface (5 degrees forward rotation). The maximal fetlock extension was less on a soft surface, in particular on the sand track (p<0.05). This decrease was most pronounced when the horses were shod with heel wedges and was least pronounced with normal shoes. In conclusion, in particular the sand track allows a forward rotation of the hoof and thus relief of pressure in the navicular area, and a decrease in maximal fetlock extension and thus unloading of the fetlock joint. The extra forward rotation of the hoof induced by heel wedges on hard tracks was almost the same on soft track surfaces. Eggbars and fibre/sand mix tracks have intermediate effects on unloading of the distal forelimb.

Animals↗

PubMed2000

[The use of electromyographic examination as a diagnostic tool and phenytoin sodium as treatment in a case of classic springhalt in a Dutch warmblood horse].

This paper describes a case of unilateral stringhalt present for 18 months in the right hind limb of a 4-year-old Warmblood gelding. The only abnormalities detected by electromyography (EMG) were a prolonged insertion activity, fibrillation potentials, and positive waves at rest and enhanced EMG activity in the right lateral digital extensor muscle on muscle contraction. This was interpreted as denervation and hyperirritability of this muscle. Both similarities and differences with Australian stringhalt could be found. As described for horses suffering from Australian stringhalt, phenytoin sodium was administered orally in a dosage ranging from 15 to 9.3 mg/kg body weight in order to try to influence the hyperflexia. Therapeutic effects without side effects could be achieved at plasma concentrations between 5.1 and 9.9 mg/L at a dosage of 12 mg/kg body weight twice daily, which is consistent with data in the literature (5-10 mg/L). The EMG examination seems to help to clarify the aetiology of the classical form of stringhalt, since the only abnormality in this patient was an abnormal electrical activity in the lateral digital extensor muscle. As in Australian stringhalt, in this type of stringhalt phenytoin also relieved the hyperflexion of the tarsus.

Animals↗

PubMed2000

Tracking down duodenopancreatic malignancy.

BACKGROUND: Malignant tumours of the duodenum are rare and often difficult to diagnose. Due to the small clinical experience with duodenal malignancies their prognosis is unknown and resection is the treatment of choice. CASE REPORT: Adding to a small series of incidental tumours, we report the case of a 65-year-old patient with primary extranodal (MALT-) lymphoma of the duodenum infiltrating the pancreatic head. The patient was admitted because of anaemia and epigastric discomfort with a history of Helicobacter-pylori associated gastric ulceration. Physical examination and bloodchemical values were otherwise normal. Endoscopy revealed duodenal ulceration but the biopsies taken from the ulceration did not give any evidence of malignancy or residual Helicobacter pylori infection. But MRT showed a circular intramural tumour of the duodenum. On laparotomy a large duodenal tumour adherent to the pancreatic head was found and a Whipple procedure was performed. CONCLUSION: Apart from describing the case of a rare lymphoproliferative disorder of the duodenum, this report illustrates the diagnostic difficulties with uncommon neoplasm's of the duodenopancreatic region and the value of MRT prior to resection of a duodenopancreatic mass.

Aged↗

PubMed1999

Peutz-Jeghers syndrome: four novel inactivating germline mutations in the STK11 gene. Mutations in brief no. 227. Online.

The diagnosis of Peutz-Jeghers syndrome is based on the occurrence of hamartomatous gastrointestinal polyps and perioral pigment spots. In view of the development of hamartomatous polyps in several syndromes and the variability of pigment spots in Peutz-Jeghers patients, identification of affected individuals is difficult. Recently, germline mutations in the STK11 gene have been reported as a molecular cause of Peutz-Jeghers syndrome. We present four novel inactivating mutations identified by direct sequencing of all 9 exons of the STK11 gene in 4 patients suggestive of Peutz-Jeghers syndrome: three frameshift mutations (125-137del; 474-480del; 516-517insT) and one nonsense mutation (Q220X). Our data obtained in these patients and in those reported previously emphasize the diagnostic value of histological discrimination between different types of hamartomatous polyps and of molecular analysis, particularly in cases with no family history of the disease.

AMP-Activated Protein Kinase Kinases↗

PubMed1999

Parenteral nutrition-induced hepatobiliary dysfunction in infants and prepubertal rabbits.

We analyzed clinical, biochemical, and histo- logic parameters of ten infants with parenteral nutrition-induced hepatobiliary dysfunction. The data were compared with the results of a rabbit model. All infants were born prematurely with low birth weight. Their clinical diagnoses were necrotizing enterocolitis (6), gastroschisis (1), intrauterine volvulus (1), and lung hypoplasia (2). All required total (TPN) or partial parenteral nutrition for at least 8 weeks. All had repeated episodes of infections or sepsis. A rise in bilirubin and aminotransferase levels occurred after a minimum of 5 weeks; peak bilirubin levels ranged from 4 to 14 mg% and aminotransferases from 40 to 140 IU/l. One child later developed gallstones. Liver biopsies after 1 to 24 months showed fibrosis, bile-duct proliferation, cholestasis, and hydropic degeneration. All of the above-mentioned clinical factors have been accused of causing the observed biochemical and histologic changes. In our rabbit model we were able to produce almost identical symptoms by TPN alone: gallbladder distension, sludge, and stones developed after 1-4 weeks of TPN as well as uncharacteristic changes in aminotransferases and bilirubin after 4 weeks. Liver histology revealed severe hydropic degeneration of zone 3 as early as 1 week after beginning TPN. A rise of fibrosis and bile-duct proliferation after 1 to 4 weeks of infusion was statistically significant. Cholestasis, as was observed in the infants, could not be detected. In our model, all alterations observed could be attributed exclusively to TPN. We therefore assume that TPN was the true cause of the dysfunction. In a second experimental series infusions were reduced to 80% PN and free access to lab chow. These animals produced normal feces, indicating physiologic enteral stimulation. They developed the same degenerative and proliferative histologic changes, whereas gallbladder distension, sludge, and stones were not noted. We conclude that: (1) The TPN solution itself is responsible for the histologic changes in the liver, which is supported by the fact that hydropic degeneration of zone 3 is typical of a direct toxic effect; and (2) Complete enteral starvation with an absence of enteral stimulation causes disease of the lower biliary tract.

Animals↗

PubMed1999

Lactobacillus perolens sp. nov., a soft drink spoilage bacterium.

Lactic acid bacteria that are able to spoil soft drinks with low pH comprise a limited number of acidotolerant or acidophilic species of the genera Lactobacillus, Leuconostoc and Weissella. Various Gram-positive rods causing turbidity and off-flavour were isolated from orange lemonades. Physiological and biochemical studies including SDS-PAGE whole-cell protein analysis showed a homogeneous group of organisms. The 16S rRNA gene sequence analysis of two representatives revealed that they formed a phylogenetically distinct line within the genus Lactobacillus. All strains were facultatively heterofermentative, producing L-lactic acid. Based on the data presented a new species L. perolens is proposed. The name refers to the off-flavour caused by high amounts of diacetyl. The type strain of L. perolens is DSM 12744 (LMG 18936). A rRNA targeted oligonucleotide probe was designed that allows a fast and reliable identification of L. perolens.

Bacterial Proteins↗