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Biomedical subjects

W Back

Publications and source records attributed to W Back.

At least 55 records · Page 3Linked to original sources
PubMed1999

A comparison between the trot of pony and horse foals to characterize equine locomotion at young age.

The trot at 3 m/s of 24 Shetland foals ('ponies') and 24 Dutch Warmblood foals ('horses') was recorded at age 4 months on a treadmill using a modified CODA-3 apparatus to characterise equine locomotion at young age. Locomotor variables of the ponies were qualitatively and, after scaling, quantitatively compared with those of horses. Ponies made shorter strides than horses, evidenced by a shorter stance and swing duration, although their relative stance durations were similar. Neither linear nor dynamic scaling procedures could completely compensate for differences in height at the withers comparing ponies and horses. The patterns of the joint angle-time curves were similar. Ponies had a larger range of pro- and retraction, with a more protracted forelimb and a more retracted hindlimb, therefore demonstrating a more extended trot. The horses trotted with more extended elbow, stifle and tarsal joints and a more flexed hip joint, which is in accordance with the conformation for the Warmblood. The ponies moved with a stiffer trot in contrast to the more supple trot of the horses, which showed a larger maximal fetlock extension during the stance phase. In conclusion, ponies and horses move qualitatively similarly at age 4 months, but characteristic breed differences in conformation and gait quality can already be detected. Scaling methods to compensate for differences in height at the withers cannot be applied when animals move at the same velocity.

Aging↗
PubMed1999

The influence of different exercise regimens on the development of locomotion in the foal.

To study the influence of different exercise regimens on the development of locomotion, 40 Warmblood foals aged 1 week were subdivided into 3 groups: box-rest, training and pasture exercise. The box-rest group remained for 24 h a day in a box stall while the training group was housed similarly, but additionally received a 30 min workout with gallop sprints 6 times a week. The pasture group served as a control group and was kept at pasture for 24 h a day. After 5 months, the locomotion pattern at the trot of every foal was recorded overground with a 2-D MacReflex gait analysis system. A randomly selected group of 19 foals was recorded again at age 11 months after they had been kept in an open loose box with access to a small paddock without any specific training for 6 months duration. At 5 months of age the box-rest group moved with a more protracted forelimb, and more extended shoulder and elbow joints than the pasture group. Carpal and fetlock joint kinematics were rather similar in all groups. In the hindlimb, the box-rest foals were significantly different from the other 2 groups, reflected in a more retracted hindlimb, more hip extension, more flexed stifle and tarsal joints, and a larger maximal flexion of hip, stifle, tarsal and fetlock joints. In the simultaneous video recordings this locomotion pattern was visible as a hypermetric movement. The larger protraction in the forelimb and retraction in the hindlimb, as seen in the box-rest group, is opposite to the interlimb coordination of a superior moving horse. The pastured foals had a smaller range of motion of the shoulder and hip joint and less maximal step height of both fore and hind hooves, while the velocity and step length were similar between the 3 groups. Pastured foals could trot the same distance with less joint motion and therefore had a more efficient intralimb coordination. The training group moved in a way comparable with the box-rest group in the similar velocity box-rest foals trot with an abnormal, hypermetric and therefore inefficient and poorer locomotion pattern. When, superimposed on box-rest, exercise is provided in the form of gallop sprints, this will mainly improve the hindlimb locomotion. These induced differences in locomotion pattern of foals can be reversed when the foals afterwards are subjected to the same exercise regimen again.

Animals↗
PubMed1999

Immunolocalization of beta catenin in intestinal polyps of Peutz-Jeghers and juvenile polyposis syndromes.

AIM: To examine the membranous and nuclear distribution of beta catenin in the epithelial cells of gut polyps from Peutz-Jeghers syndrome and juvenile polyposis in comparison with other types of polyps and tumours. METHODS: Immunohistochemistry for beta catenin and proliferation markers was performed on conventional paraffin sections. Immunohistological staining was carried out on Peutz-Jeghers syndrome polyps from four different families, on juvenile polyposis polyps from two different families, on solitary juvenile polyps, and on hyperplastic polyps. The immunohistochemistry was evaluated qualitatively in relation to defined areas of the polyps. RESULTS: All polyps from the hamartomatous polyposis syndromes (Peutz-Jeghers syndrome and juvenile polyposis) showed nuclear localization of beta catenin in some epithelial cell nuclei. In Peutz-Jeghers syndrome polyps beta catenin positive nuclei were seen at the base of the deep crypt infoldings. In juvenile polyposis polyps and in some solitary juvenile polyps they were found in irregularly distributed cryptal epithelial cells corresponding to the proliferative compartments. Normal mucosa of the gut and hyperplastic polyps of the colon do not show nuclear staining for beta catenin. CONCLUSIONS: The dysregulation of cellular beta catenin distribution is not only a phenomenon of adenoma formation and adenoma progression in the colon--it is at least focally present in polyps of the hamartomatous type and is related to the proliferation zones of these polyps. The nuclear translocation of beta catenin most probably reflects a disturbed beta catenin metabolism. In view of the different functions of beta catenin during development and cell differentiation, the nuclear translocation of beta catenin is likely to be an important factor in enhanced cell proliferation which escapes local control mechanisms.

Adenocarcinoma↗
PubMed1999

Frequent 4-bp deletion in exon 9 of the SMAD4/MADH4 gene in familial juvenile polyposis patients.

Familial juvenile polyposis (FJP) is a hamartomatous polyposis syndrome characterized by the appearance of juvenile polyps in the gastrointestinal tract. Patients with this syndrome are at an increased risk for cancer of the colon, stomach, and pancreas. Recently, germline mutations in the SMAD4/DPC4 gene (official symbol MADH4) have been found in the majority of patients suffering from FJP. We have examined 11 unrelated patients with FJP for MADH4 germline mutations by direct sequencing of genomic DNA encompassing all 11 exons of the gene. Besides a novel mutation (959-960delAC at codon 277, exon 6) in one patient, we observed a 4-bp deletion (1372-1375delACAG) in exon 9 in two unrelated patients. Examination with microsatellite markers flanking MADH4 supports an independent origin of the mutation in these two families. The same 4-bp deletion in exon 9 has previously been described in three out of nine patients examined for MADH4 mutations. Our results combined with these previous data demonstrate that a unique 4-bp deletion in exon 9 of MADH4 accounts for about 25% of all FJP cases and that other MADH4 mutations occur in an additional 15% of patients. Genes Chromosomes Cancer 25:403-406, 1999.

Adenomatous Polyposis Coli↗
PubMed1999

Idiopathic myelofibrosis with extramedullary hematopoiesis in the kidneys.

Extramedullary hematopoiesis is a common finding in idiopathic myelofibrosis and is usually found in liver and spleen. We report on a patient with biopsy-proven myeloid metaplasia and fibrosis of the renal parenchyma as a rare cause of chronic renal failure. The renal biopsy specimen showed numerous infiltrates of hematopoietic cells expressing growth factors like M-CSF, GM-CSF, IL-1beta and PDGF while TGF-beta was not elevated. These findings suggest that hematopoietic growth factors play a key role in the pathogenesis of this condition causing proliferating fibrosis and enlargement of the kidneys.

Aged↗
PubMed1998

[Argon plasma coagulation in treatment of hereditary hemorrhagic telangiectasia of the nasal mucosa].

Patients with hereditary hemorrhagic telangiectasia (M. Osler-Rendu-Weber disease) often suffer from recurrent epistaxis that poses considerable therapeutic problems. Dermoplasty, electrocoagulation, laser coagulation, iridium brachytherapy and systemic administration of estrogens have been proposed for treatment. Until recently argon plasma coagulation (APC) was not used in ENT surgery, but theoretical considerations render APC a promising therapeutic method for controlling nasal bleeding. Coagulation of tissue is limited to 1-2 mm of penetration and therefore risk of damage to adjacent tissue is low. Effects are best in tissues with high electric conductivity, especially for coagulating bleeding lesions and blood vessels. We have now treated four patients with telangiectasias in the nasal mucosa who had long histories of treatment for epistaxis. The patients were satisfied with the postoperative results and the frequency and intensity of bleeding were significantly reduced. Initial clinical experiences show that APC is a useful alternative for the treatment of bleeding telangiectasias in the nasal mucosa.

Adult↗
PubMed1998

Autologous transplantation of urothelium into demucosalized gastrointestinal segments: evidence for epithelialization and differentiation of in vitro expanded and transplanted urothelial cells.

PURPOSE: Our study established a technique for in vitro expansion and subsequent transplantation of autologous urothelial cells into vascularized seromuscular segments from stomach and colon in sheep. The proof of proliferation and differentiation of the transplanted urothelium in the absence of resident urothelium is considered to be a prerequisite for use of this technique in bladder augmentation. MATERIALS AND METHODS: Autologous sheep urothelial cells were expanded in vitro and grown on collagen membranes for sheet grafting. Using a vital stain, viability and confluency status of the urothelial graft were determined before transplantation into demucosalized segments isolated from the sheep stomach and colon gastrointestinal pouches. The gastrointestinal segments were sewn up and remained in the abdomen as small pouches stiched to the abdominal wall. Take and differentiation of transplanted cells within the pouch were assessed two and three weeks later using histological and immunohistological means. RESULTS: Urothelial cells grew well on collagen membranes. A confluency status > 40% and co-culturing with 3T3 feeder cells favored successful transplantation. Two weeks after transplantation a multilayered urothelial-like epithelium was found to line the lumen of the pouch. The epithelium was characterized by a distinct urothelium-typical distribution of basal and luminal keratins and the expression of the umbrella cell-specific marker uroplakin III. Moreover, the epithelium had an underlying basal lamina which focally contained collagen type IV. CONCLUSIONS: The data indicate that in vitro expanded urothelial cells are capable of epithelializing demucosalized gastrointestinal segments forming a genuine, differentiated "neo" urothelium.

Animals↗
PubMed1998

Lactobacillus amylolyticus sp. nov., isolated from beer malt and beer wort.

Some of the strains used for the biological acidification in breweries belong to L. delbrueckii subsp. delbrueckii, L. delbrueckii subsp. lactis or L. fermentum. However, more recent studies showed that most strains isolated are physiologically different from the above mentioned species and were tentatively allocated to Lactobacillus amylovorus. Genotypic studies of 25 strains exclusively isolated from beer malts and beer worts, showed, that there were differences to the type strain of L. amylovorus concerning DNA-DNA similarities and the sequences of their 16S and 23S rRNA genes. Therefore, we propose to combine these strains in a new species of the genus Lactobacillus, namely L. amylolyticus. Strain DSM 11664 is proposed as the type strain. An rRNA targeted oligonucleotide probe was designed that allows a fast and reliable identification of Lactobacillus amylolyticus.

Bacterial Typing Techniques↗
PubMed1998

Peutz-Jeghers syndrome is caused by mutations in a novel serine threonine kinase.

Peutz-Jeghers (PJ) syndrome is an autosomal-dominant disorder characterized by melanocytic macules of the lips, multiple gastrointestinal hamartomatous polyps and an increased risk for various neoplasms, including gastrointestinal cancer. The PJ gene was recently mapped to chromosome 19p13.3 by linkage analysis, with the highest lod score at marker D19S886. In a distance of 190 kb proximal to D19S886, we identified and characterized a novel human gene encoding the serine threonine kinase STK11. In a three-generation PJ family, we found an STK11 allele with a deletion of exons 4 and 5 and an inversion of exons 6 and 7 segregating with the disease. Sequence analysis of STK11 exons in four unrelated PJ patients has identified three nonsense and one acceptor splice site mutations. All five germline mutations are predicted to disrupt the function of the kinase domain. We conclude that germline mutations in STK11, probably in conjunction with acquired genetic defects of the second allele in somatic cells, cause the manifestations of PJ syndrome.

AMP-Activated Protein Kinase Kinases↗
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

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

Expression of tenascin in lymphocytic autoimmune thyroiditis.

AIMS: To study the distribution of tenascin by immunocytochemistry in autoimmune diseases of the thyroid. METHODS: Thyroids from patients with inflammatory lesions of the thyroid (lymphocytic thyroiditis Hashimoto, Grave's disease, thyroiditis DeQuervain) were studied by immunocytochemistry using antibodies against tenascin, collagen III, and collagen IV. RESULTS: In autoimmune lymphocytic thyroiditis Hashimoto there was a characteristic corona-like staining pattern of tenascin around all activated lymph follicles with germinal centres. This staining pattern contrasted with the immunoreactions for collagen III and IV, which were not enhanced in the perilymphofollicular interstitium. In cases of thyroiditis DeQuervain the areas of early and ongoing fibrosis showed some diffuse staining for tenascin and for collagen III. Enhanced diffuse immunostaining for collagen IV in the perivascular and interfollicular interstitium was present in cases of Grave's disease. In Grave's disease no characteristic immunoreaction was detectable for tenascin. CONCLUSIONS: The corona-like expression of tenascin around lymphofollicular infiltrates is distinctive of cases of lymphocytic thyroiditis. A similar staining pattern for tenascin has been reported in lymphoid hyperplasia of the thymus associated with myasthenia gravis, another autoimmunological disorder. There are good arguments that the activation and infiltration of lymph follicles in the thyroid during the course of autoimmune diseases lead to stimulation and activation of the surrounding mesenchyme producing tenascin as part of the extracellular matrix.

Biomarkers↗
PubMed1996

[Chronic recurrent subileus due to Strongyloides stercoralis infection under immunosuppressive therapy].

HISTORY AND CLINICAL FINDINGS: A 33-year-old woman from Laos was admitted due to recurrent vomiting and weight loss. Since one year, she was receiving immunosuppressive therapy (azathioprine 50 mg/d and methylprednisolone 18 mg/d) for a mixed connective tissue disease. Because of a drug induced Stevens-Johnson-Syndrome one month earlier high doses of methylprednisolone (100 mg/d intravenously) had been administered. The patient's general condition was reduced. Examination elicited a mild pain in the middle abdomen on palpation but no resistance or tumour. The differential diagnosis included obstructive and (or) inflammatory disease of the gastrointestinal tract. INVESTIGATIONS: Elevated IgE-levels (1111 IU/ml; normal up to 100 IU/ml) and eosinophilia (8%) lead to the suspicion of a helminthiasis. Oesophagogastroduodenoscopy showed a significant duodenal stenosis. Duodenal biopsy revealed a severe infestation with Strongyloides stercoralis. Stool examinations were negative though. TREATMENT AND COURSE: With administration of thiabendazole (2 g/d) a rapid recovery was noted. A second oesophagogastroduodenoscopy one week after the onset of therapy revealed no further stenosis. Since there was no activity of the mixed connective tissue disease the methylprednisolone dosage was reduced and the administration of azathioprine was ceased. 3 weeks after beginning of treatment the patient was discharged in improved condition. CONCLUSION: In immunocompromised patients suffering from gastrointestinal complaints who have been in endemic areas an infection with Strongyloides stercoralis should be excluded. Without treatment, this helminthiasis may be fatal.

Adult↗
PubMed1996

Comparative genomic hybridization (CGH) discloses chromosomal and subchromosomal copy number changes in Merkel cell carcinomas.

We analyzed three Merkel cell carcinomas (MCC), applying comparative genomic hybridization (CGH) with DNA from paraffin-embedded and cultured tumor material as the probes. By this method, numerous changes in chromosome copy numbers were observed in each tumor investigated. Recurrent gains of chromosomes 1, 6, 18q and 20 were detected in two tumors. A third tumor showed complex chromosomal copy number changes, including gain of chromosome 8 and 9. These gains, as well as gain of chromosome 1 in the first two tumors, were confirmed by fluorescence in situ hybridization to paraffin tissue sections. Our results support the view that important genes for MCC development may be located on chromosomes 1, 6, 18q and 20.

Aged↗
PubMed1996

Morphologic distribution of transforming growth factor alpha in the gastrointestinal tract--its presence in neuroendocrine cell type of the colon mucosa.

Among the growth factor proteins of the epidermal growth factor (EGF)-family especially the transforming growth factor alpha (TGF-alpha) and EGF can be detected in the mucosa of the gastrointestinal tract. In this study, immunohistochemistry on 15 different human tissue probes of gastrointestinal and colonic mucosa was carried out to visualize possible deposits for TGF-alpha in the mucosa and to compare different compartments of the upper and lower gastrointestinal epithelium. Most interestingly, in the colon there is a strong TGF-alpha-like immunoreactivity in neuroendocrine cells as evidenced by double labeling experiments with common neuroendocrine markers and by immunoelectron microscopy. In the upper gastrointestinal epithelium, however, all neuroendocrine cell types are negative for TGF-alpha, but parietal cells of the gastric corpus epithelium show strong cytoplasmic immunostaining for TGF-alpha. The neuroendocrine cells of the colon-harboring TGF-alpha-like immunoreactivity in their neurosecretory granules belong morphologically to the so-called L-cell type. Along with the well-known presence of EGF-receptor in the mucosa of the gastrointestinum, TGF-alpha, which is very likely to be released by this neuroendocrine cell type of the colon, acts in a paracrine mode. These findings represent the first morphologic indication that in the colonic epithelium growth regulation is under neuroendocrine control.

Colon↗
PubMed1996

In vitro determination of equine third metacarpal bone unloading, using a full limb cast and a walking cast.

OBJECTIVE: To improve fracture treatment, in vitro experiments were performed to study the influence of a full limb cast and a walking cast on the loading regimen of bones in the distal portion of the equine forelimb. ANIMALS: 6 forelimbs of 6 Shetland ponies. PROCEDURE: Loading of the third metacarpal bone was considered a representative measure for distal limb loading. Electrical resistance rosette strain gauges were attached to the dorsal, palmar, medial, and lateral surfaces of the midshaft of this bone in 6 forelimbs of 6 Shetland ponies. The limbs were tested in a pneumatic loading device to a maximal load of 1,500 N. RESULTS: Both casts decreased the amount of compressive forces acting on the metacarpal bone. Application of a full limb cast resulted in a variable and eccentric decrease, remaining strains ranging from 84 to 7% of the baseline value. A walking cast was superior in that it gave a centric and more uniform reduction of compressive loading to < 11% of the baseline value. Moreover, a walking cast neutralized the bending and torsion components of the loading. CONCLUSION: This study confirmed the clinical experience that a walking cast creates more reliable and favorable conditions for healing of fractures than does a full limb cast.

Animals↗
PubMed1996

Are kinematics of the walk related to the locomotion of a warmblood horse at the trot?

In purchase examinations or at studbook selection sales the locomotor apparatus of horses is judged both at walk and trot. To evaluate whether kinematics of the walk are related to the locomotion at the trot, fore and hind limb movements of a group of 24 26-month-old warmbloods were recorded at walk and trot on a treadmill (1.6 and 4 m/s) using a modified CODA-3 gait analysis system. The intralimb coordination patterns at walk and trot were compared, and temporal and spatial variables of these gaits were related. Stride and stance durations (s) were shorter at the trot, while the stance distance (m) and swing duration (s) remained the same. Moreover, the pattern of the joint angle-time curves at walk and trot looked rather similar, though shifted to the left at trot because of the shorter relative stance duration. During the stance phase, the shoulder, stifle and tarsal joints were more flexed throughout, while the carpal and fetlock joints were more maximally extended in the trot than in the walk. In the swing phase, the elbow, carpal, stifle, and tarsal joints were more flexed because of the higher 'operating' speed at the trot compared to the walk. All other kinematic variables at the trot could be predicted from the mean +/- lsd of the values recorded at the walk. Moreover, nearly all kinematic variables at the walk correlated well with those at the trot, while variables indicating gait quality of the walk were similar to the ones identified previously for the trot. In conclusion, kinematics recorded at the walk in a group of horses were similar to and thus predictive for locomotion at the trot providing the decreased stance duration and the increased speed of the trot are taken into consideration.

Animals↗