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Biomedical subjects

W Hein

Publications and source records attributed to W Hein.

At least 37 records · Page 2Linked to original sources
PubMed1998

Biomechanical and densitometric bone properties after callus distraction in sheep.

Assessment of biomechanical stability of diaphyseal bone lengthened by callus distraction is an unsolved problem. A middiaphyseal corticotomy was performed in the left tibia of 24 sheep. After 7 days, callus distraction was begun at a rate of 0.5 mm every 12 hours for 30 days using a standard unilateral fixator system. Animals were euthanized 4, 8, or 12 weeks after the end of distraction. The lengthened tibia and the contralateral control tibia from each animal were evaluated by radiographic, densitometric (dual energy xray absorptiometry, quantitative computed tomography), and biomechanical (axial compression testing, torsion testing to failure) methods. The bone mineral density and maximum torque for the lengthened tibia were significantly greater in the 8-week group than in the 4-week group. However, the values in the 12-week group were significantly smaller than in the 8-week group. In the lengthened tibias, there was a correlation between the maximum torque and the bone mineral density, and between the maximum torque and the bone density. Bone density measurements are useful prognosticators for the safe removal of external fixators after leg lengthening procedures. By using these methods, clinical fractures after leg lengthening could be avoided in the future.

Absorptiometry, Photon↗
PubMed1998

[Possibilities of follow-up imaging after implantation of a carbon fiber-reinforced hip prosthesis].

INTRODUCTION: There are many problems in the radiological diagnosis of aseptic loosening in total hip arthroplasty. Computed tomography (CT) and magnetic resonance tomography (MRT) are not usable for metallic implants (stainless steel, cobalt alloy, titanium alloy). MATERIAL AND METHODS: From April 1993 to December 1993 15 CFRP non-cemented hip prostheses have been implanted. In a prospective clinical study plane radiographs, CT and MRT have been analysed. RESULTS: Three stems were revised (1 femoral fracture, 1 severe thigh pain, 1 aseptic loosening). CFRP are not visible in plane radiographs. There was a complete (two-third of the cases) or nearly complete (one-third of the cases) small sclerotic interface between the prosthesis and the bone, these were apparent in CT and MRT in stable implant cases and did not have any clinical correlations. DISCUSSION: The small sclerotic interface is quite different in comparison to so called "Reactive Lines". In one case of aseptic loosening there was an interposition of soft tissue between prosthesis and bone in MRT and CT. CFRP inaugurates new diagnostic possibilities in aseptic loosening of hip prosthesis and in tumour surgery too.

Aged↗
PubMed1996

Dega acetabuloplasty combined with intertrochanteric osteotomies.

Between 1973 and 1984, 70 modified Dega acetabuloplasties done simultaneously with intertrochanteric osteotomies in 51 patients with developmental dysplasia of the hip were reviewed for long-term results and analyzed for causes of failure. Mean patient age at operation was 2.9 years (range, 8 months-8 years), and mean followup time was 15.2 years (range, 10-19 years). Topical investigations were based on clinical criteria of the Severin classification and radiologic criteria of the Commission for the Study of Hip Dysplasia of the German Society of Orthopaedics and Traumatology. The review of clinical documents and investigations very good and good results in 80% of the hips. The Trendelenburg sign was a useful clinical indicator for problematic cases. Measurements on radiographs were classified into deviation grades from the normal range. Values of the acetabulum and the acetabulum to head relation were normal or slightly abnormal in >80% of hips. Measurements of the femoral head and neck were in the low normal range. The lowest percentage of normal values was in 24 cases with coxa valga after acetabuloplasty combined with derotational varus osteotomy. Poor clinical and radiologic outcome usually was the result of avascular necrosis of the femoral head or recurring valgus deformity after derotational varus osteotomy. The rate of avascular necrosis as a consequence of the operation was 5.7%. The risk of avascular necrosis caused by derotational varus osteotomy is lower than the risk of later development of deformities in the proximal femur.

Acetabulum↗
PubMed1996

Tibial lengthening. Epiphyseal and callus distraction compared in 39 patients with 3-14 years follow-up.

We examined 32 patients with 39 lengthenings (mean 8 cm) of the lower leg 3-14 years postoperatively. 23 distraction epiphyseolyses and 16 corticotomies with callus distraction had been carried out using the llizarov system. Both procedures yielded the same healing indices and the number of problems and complications was the same in the two groups. After distraction epiphyseolysis, serious complications of the knee and greater deviations from the normal leg axis were commoner than after callus distraction, which we now prefer.

Adolescent↗
PubMed1995

Hydroxyapatite-coated hip prostheses. Early results from an international study.

A hydroxyapatite-coated hip prosthesis designed to stimulate proximal femoral stress transfer was studied in 222 patients undergoing primary total hip arthroplasty with a minimum followup of 2 years. The femoral component was a roughened titanium alloy with a 50-mu coating of hydroxyapatite applied to the proximal third. A proximal press-fit technique was applied with distal femoral over-reaming as standard procedure. The hydroxyapatite-coated acetabulum was of hemispherical design. Analysis of the clinical results showed a mean Merle D'Aubigné score of 16.7 points at 6 months and 17.4 points at 2 years. Mild residual thigh pain of unknown origin was reported in 3.6% of patients at 2 years. Radiographic evaluation showed complete acetabular and proximal femoral osseointegration without any loosening. No radiolucency or reactive line formation was observed around the hydroxyapatite-coated areas of the prostheses. Femoral bone densification occurred at the coated-uncoated transition zone (54%); 4% to 6% of cases showed cortical hypertrophy at the uncoated area of the stem. Reactive lines were seen around the distal stem in 52% of patients after 2 years. The clinical outcome was excellent, and the radiographic data pointed mainly to proximal femoral stress transfer.

Adult↗
PubMed1993

Contribution to some phenotypical characteristics of Vibrio cincinnatiensis. Studies in one strain of a diarrhoeic human patient and in two isolates from aborted bovine fetuses.

Until now, only a few strains of V. cincinnatiensis have been isolated. This study describes a further three isolates which originated in one case from a stool specimen of an immunocompromised elder patient suffering from enteritis and in two cases from the rennin stomachs of aborted bovine fetuses. These strains grew on TCBS, CIN, MacConkey and XLD plates. Their biochemical activities were dependent on NaCl concentration, in particular the formation of indole, lysine and ornithine decarboxylases, arginine dihydrolase, the reduction of nitrate and behaviour in the Voges-Proskauer test. Moreover, lysine decarboxylase and nitrate reductase were temperature-dependent. The knowledge of these hitherto unknown phenotypical characteristics may facilitate the diagnosis of the pathogen.

Abortion, Veterinary↗
PubMed1991

The intestinal habitat for organized lymphoid tissues in ruminants; comparative aspects of structure, function and development.

Unlike the Peyer's patches of rats and mice, which are considered to be secondary lymphoid organs, the ileal Peyer's patch of sheep is thought to be responsible for the primary generation of B cells, like the bursa of Fabricius of birds. The ileal Peyer's patch of sheep shows prenatal maturation, antigen-independent lymphopoiesis, a rate of lymphocyte production larger than that of the thymus, and involution at a young age. Follicles contain few T cells and have an IgM+, relatively immature B lymphocyte population, as judged by B-cell differentiation markers. The follicle-associated epithelium of the ileal Peyer's patch is of a special type that sheds carbonic anhydrase-rich, 50-nanometer membrane-bounded particles (carbonic anhydrase-reactive particles; CAP) into the intercellular spaces. The CAP filter into the follicle centre and are taken up by lymphocytes. They represent the epithelial (bursa-like) element in an otherwise mesenchymal stroma of reticular cells embedding the follicle lymphocytes. Transepithelial transport of macromolecules, with the formation of multivesicular body-like cytoplasmic vacuoles, appears to be the basis for CAP formation. The jejunal Peyer's patches are devoid of CAP, persist in the adult animal, contain M cells with clusters of B cells in the follicle-associated epithelium, and have many CD4+ lymphocytes in the follicles and in the interfollicular areas. Aggregates of lymphoid follicles in the large intestine resemble the jejunal Peyer's patches with respect to their lymphocyte population and the ileal Peyer's patch with respect to their follicle-associated epithelium.

Animals↗
PubMed1990

Class I major histocompatibility complex cDNA clones from sheep thymus: alternative splicing could make a long cytoplasmic tail.

To investigate the class I major histocompatibility complex (MHC) genes expressed in the young sheep thymus, a cDNA library was screened with a human HLA-B7 cDNA probe under conditions of relaxed stringency. Thirteen clones were isolated and found by partial sequences to fall into five classes, requiring the expression of at least three loci. One sequence was found six times, almost half of the total, and may thus represent the major message expressed in the young sheep thymus. One of the clones was found to have failed to excise the intron between cytoplasmic exons 7 and 8, leading to the predicted synthesis of a cytoplasmic domain 23 amino acids longer than the other sheep sequences, and 15 amino acids longer than any cytoplasmic domain previously described. The sequences of all the clones were found to be most similar to bovine, and least similar to mouse class I MHC sequences.

Amino Acid Sequence↗
PubMed1990

[Modification of lipoxygenase products in bone by the linoleic acid content of the diet].

Eicosanoids are supposed to participate in the regulation of bone metabolism. 30 male white rats of the wistar strain were fed on a diet rich in linoleic acid (LA), on a diet poor in LA and on a pellet diet after 3 month up to an age of 5 month. The formation of leukotrienes (LT) C4, D4, and E4 from the proximal tibia metaphysis after LA rich diet has been compared to the formation from LA poor and pellet diet. LA rich diet increased the formation of LTC4, D4 and E4 in the proximal tibia metaphysis. The properties of eicosanoids as local mediators in the bone were discussed.

Animals↗
PubMed1990

[The surgical treatment of knee joint extensor muscle contractures].

It is reported about the results after operative mobilization of knee joint in 19 patients with contractures of extension muscles of knee joints. After operative arthrolysis and/or Payr-Plasty the range of motion has increased on average from 23 degrees to 92 degrees (a relative gain of 52%). Patients with traumatic knee contracture of extension muscle achieved an improvement in the range of movement on average by 76 degrees, whereas those with contracture due to infection improved on average by only 43 degrees. The etiology, the duration, and the preoperative loss of movement are important for success of treatment.

Adult↗
PubMed1990

[Changes in the spongiosa density in the femoral head of rabbits in atherosclerosis].

Modulations of spongiosa density in the femoral head of rabbits by atherosclerosis. In a long-term study 31 rabbits (+5 control animals) were fed about 20 weeks on a diet rich in cholesterol. An important observation in this study was, that spongiosa density in the femoral head decreases after cholesterol rich diet in contrast to the control group. This effect could be modulated by the Trapidil AR 12463 content (50 mg/die) of the diet, but not by the high density lipoprotein application. Serum cholesterol levels and induced atherosclerosis were determined. Correlations between spongiosa density and atherosclerosis were discussed.

Animals↗
PubMed1989

[Prostaglandins--local regulators in bone?].

Since the initial discovery by Bergström, prostaglandin E has been the focus of an intense research effort in vitro and in vivo. The regulation of bone resorption and formation involves local as well as systemic factors. In the last decade, prostaglandins have been found to be intimately associated with bone metabolism. One hypothesis consistent that osteoblastic c AMP levels play a central role in determining whether osteoblasts stimulate or inhibit osteoclastic bone resorption. The osteoinductive properties of prostaglandins were discussed.

Animals↗
PubMed1989

[The significance of Ilmaplant as a bone substitute with reference to prostaglandin biosynthesis in bones. An animal experiment-clinical study].

The paper pointed out the resorbable material Ilmaplant-R and the glass ceramic Ilmaplant-L which are used for bone substitution. X-ray, histomorphometric and total mineral contents study were carried out in the region of healing defects in the tibia of 60 male white wistar rats. The healing response of the two bioceramics was compared 12 weeks after implantation. The inductive properties of prostaglandins were discussed. The possibilities of clinical application of Ilmaplant-R were demonstrated on the basis of short-term results up to 12 months.

Animals↗
PubMed1989

[Our ideas for treatment of dislocated dysplastic hip in early childhood].

The early diagnosis and treatment of congenital dislocation of the hip cannot prevent the manifestation of luxation in every case. The following operative treatment should include not only the open reposition, but also all deformities of the upper femur and the acetabulum. This combined procedure is already possible in the infancy starting from the 6th month. The correction of increased antetorsion and CCD-angle alone respectively the increased acetabular angle is not indicated. The spontaneous normalization of the not operated part of the hip can be find only in a minimal part of cases. The stabilization of bone defect in the acetabuloplastic by Dega is performed by allogenic deep frozen cortico-cancellous bone grafts successfully.

Acetabulum↗
PubMed1989

[The possible role of occupational factors in influencing the manifestation of idiopathic femur head necrosis].

The idiopathic necrosis of the femoral head of adults is increasing. The disease appears in the age from 20 to 40 years and leads to the destruction of the femoral head. The final state is often a severe osteoarthrosis of the hip joint already in the efficient lifetime. The etiology of the idiopathic necrosis of the femoral head is not yet cleared up. There were only few information about possible professional factors. In a study the professional anamnesis of 153 patients were utilized. Thereby high portions of works with dynamic and static charges and expositions of vibrations were found.

Adult↗
PubMed1988

Recombinant human interferon alpha-2a: delivery to lymphoid tissue by selected modes of application.

The effect of different parenteral administration routes (i.d., s.c., i.v.), infusion rates, and albumin contents of the drug vehicle on the cumulative recovery of recombinant human interferon alpha-2a (rIFN alpha-2a) in lymph and on its concentration in blood and lymph was determined in sheep. Blood samples were withdrawn from a jugular vein catheter and lymph was collected from a cannulated efferent popliteal lymphatic duct. The concentration of rIFN alpha-2a in lymph and blood plasma samples was measured by an enzyme immunoassay. Following i.v. infusion of 2 x 10(7) U of rIFN alpha-2a, the peak concentrations measured in blood plasma and lymph, respectively, were 8250 and 14 U/ml. The concentration measured in lymph after i.d. or s.c. administration of the same dose was about 10(5) times higher (peak concentration, 3.1 x 10(6) U/ml), while blood plasma levels remained low (peak concentration, 315 U/ml). The cumulative recovery of rIFN alpha-2a in lymph following i.d. or s.c. administration was 59.2 +/- 7% (mean +/- SD; N = 8) and was affected neither by the infusion rate nor by the coadministration of albumin. Our data indicate that following i.d. or s.c. administration, rIFN alpha-2a (MW 19,000) is absorbed mainly by the lymphatics. This results in high levels of rIFN alpha-2a in the lymph which drains from the application site to the regional lymph nodes. The knowledge gained in this investigation may help to improve the mode of administration and therapeutic efficacy of protein drugs whose targets are lymphoid cells.

Absorption↗