Biomedical subjects

W Lierse

Publications and source records attributed to W Lierse.

At least 19 recordsLinked to original sources

PubMed1997

Cartilage-flow phenomenon and evidence for it in perichondrial grafting.

The cartilage-flow phenomenon has been frequently described but not in connection with transplantation procedures for treatment of cartilage lesions. Consequently, we examined this particular phenomenon in an experimental sheep model originally set up to study the use of perichondrial grafts for repair of full-thickness cartilage lesions. Osteochondral lesions were made in nonweight-bearing and weight-bearing areas of knee joints in 36 sheep. The defects were filled with autologous rib perichondrial grafts and secured by either collagen sponges or fibrin glue (n = 24 animals). Defects without perichondrial grafts served as controls (n = 12 animals). Following 1 week of immobilisation of the operated leg, the plaster was removed, and animals were allowed to move freely. Animals were killed after 2, 4, 12 and 16 weeks. Grafts including rims of original surrounding cartilage and bone were removed and investigated by means of macroscopy, histology and micromorphology, including scanning electron microscopy and analysis under polarized light. Cartilage flow was observed in all specimens by 4 weeks after drilling the defects, independent of the weight-bearing condition. These flow formations exhibited a bending of the collagen fibres centrally into the defects, reduction of metachromasia, cell cluster formation and areas of reduced cell density. Time-dependent flow formations were observed related to the weight-bearing condition and whether or not the defects had been grafted. In grafted, non-weight-bearing defects further cartilage flow was stopped 8 weeks after transplantation by the growing perichondrial transplants, which had filled the defects completely. In contrast, control defects exhibited further flow formations in both areas. The same was observed in grafted defects in the weight-bearing area. In defects without complete filling as not enough spontaneously growing fibrous tissue had arisen from the bottom of the defects, two different observations were made: either the defects exhibited a fungiform mass of fibrous tissue that had overgrown the lateral flow formations, or the central mass of fibrous tissue was overgrown by the lateral flow formations. In conclusion, cartilage flow seems to be a mechanically induced phenomenon at the rims of cartilage lesions that contributes little to the reduction of size of large osteochondral defects. There was no evidence for new cartilage proliferation or production of cartilaginous matrix at the rims of the lesions.

Animals↗

PubMed1996

Variability of femoral muscle attachments.

Analytical and experimental models of the musculoskeletal system often assume single values rather than ranges for anatomical input parameters. The hypothesis of the present study was that anatomical variability significantly influences the results of biomechanical analyses, specifically regarding the moment arms of the various thigh muscles. Insertions and origins of muscles crossing or attaching to the femur were digitized in six specimens. Muscle volumes were measured; muscle attachment area and centroid location were computed. To demonstrate the influence of inter-individual anatomic variability on a mechanical modeling parameter, the corresponding range of muscle moment arms were calculated. Standard deviations, as a percentage of the mean, were about 70% for attachment area and 80% for muscle volume and attachment centroid location. The resulting moment arms of the m. gluteus maximus and m. rectus femoris were especially sensitive to anatomical variations (SD 65%). The results indicate that sensitivity to anatomical variations should be analyzed in any investigation simulating musculoskeletal interactions. To avoid misinterpretations, investigators should consider using several anatomical configurations rather than relying on a mean data set.

Aged↗

PubMed1995

[Angio-architecture of the colon in Crohn disease and ulcerative colitis. Light microscopy and scanning electron microscopy studies with reference to the morphology of the healthy large intestine].

The etiology and the pathogenesis of the chronic inflammatory bowel diseases known as Crohn's disease and ulcerative colitis have not been defined. Therefore, in this study the main emphasis was placed on description of the pathologic anatomy. Disturbed blood supply and vascular disorders have been discussed as etiopathogenetic factors. The results in the literature are frequently contradictory. For this reason, the vascular system of the colon in Crohn's disease and ulcerative colitis was systematically examined by means of various morphological methods in this study. Microvascular corrosion casting and translucent specimens were taken from operative specimens taken from 12 patients with Crohn's disease and 8 with ulcerative colitis. For comparison, tumor-free parts of 6 colon cancer specimens were examined. The evaluation was done by scanning electron- and/or stereoscopic microscopy. In the presence of chronic inflammatory bowel disease dilatation of the submucosal veins, caliber differences in the tunica muscularis and rarefaction of the penetrating blood vessels were found. In summary, an impairment of the blood flow in the tunica muscularis can be postulated. For the first time, the resulting venous stasis has been described, in contrast to the previously described disturbed arterial blood supply.

Adult↗

PubMed1995

[New kinds of 3-dimensional atlases of the anatomy and function of the human body].

It is a drawback of classical multimedia programs for the visualization of spatial knowledge, that they are based on a limited number of predefined views. This paper describes a model that combines pictorial and symbolic knowledge about spatial structures in a way that allows arbitrary views of the scene and the interrogation of the model in the context of the actual view. The style of the pictorial presentation only depends on the objective and the phantasy of the user. The functionality of the approach is demonstrated with the example of the human head. It is furthermore shown that the model potentially allows the simulation or generation of all classical visual teaching aids for anatomy.

Anatomy, Artistic↗

PubMed1994

The in vitro influence of different culture conditions on the potential of sheep rib perichondrium to form hyaline-like cartilage. Evaluation of gluing materials used for in vivo graft fixation.

The effectiveness of autologous rib perichondrium for repair of full-thickness hyaline cartilage defects has been shown experimentally and clinically in various reports. The purpose of this study was to examine the behaviour of sheep rib perichondrial tissue under in vitro conditions and the influence of different culture matrices in order to evaluate possible stimulating effects. Rib perichondrium was obtained from sheep used for an experimental in vivo trial. After removal of adjacent cartilage remnants the tissue was divided and specimens cultured for 14 days in different ways. Explants cultured on collagen sponges (group A), fibrin glue (group B) and cellulose acetate filter (group C) were examined histologically, histochemically, histomorphometrically and autoradiographically. Clear differentiation of perichondrial cells towards a chondrocyte-like cell shape, particularly in the proliferation zone, was noticed on all matrices. These cells synthesized new matrix substances comparable to the ground substance normally present in hyaline cartilage. Morphometric comparison of tissue differentiation on different culture matrices revealed no significant differences in proliferation rates.

Animals↗

PubMed1994

Anal endosonography in healthy subjects and patients with idiopathic fecal incontinence.

PURPOSE: This study investigates the normal ultrasonographic morphology of pelvic floor striated muscle and evaluates whether there are differences between males and females and between healthy subjects and patients with idiopathic fecal incontinence. METHODS: Manometric and ultrasonographic studies of the anal canal were performed in 30 healthy volunteers and in 26 patients with idiopathic fecal incontinence. Verification of ultrasonographic findings was obtained by studying anatomic preparations. RESULTS: Ultrasonography reliably identified the internal and external anal sphincter and frequently visualized neighboring structures. In addition, it detected muscular structures that have not clearly been described previously. However, differences in external sphincter function between males and females and between healthy subjects and incontinent patients were not reflected by alterations in muscle thickness. CONCLUSIONS: Endosonography of the anal canal clearly delineates muscular structures and may even visualize structures that have been previously incompletely defined. However, it remains to be shown that differences in certain muscular functions have a morphologic correlate that can be detected by endosonography.

Adult↗

PubMed1994

[Thermal side effects after use of the pulsed IR laser on meniscus and bone tissue].

Thermal effects on meniscus and bone tissue after application of 314 boreholes using five different infrared (IR) lasers: Nd:YAG, Tm:YAG, Ho:YAG, Er:YAG, Cr,Er:YSGG (application energy 200 mJ, 400 mJ, 600 mJ, 800 mJ, 1000 mJ; repetition rate 2 Hz, 5 Hz; medium air, water rinse) were analyzed. The experimental set-up comprised for the beam guiding a focussing lens (f = 100 mm) or a flexible fiber (Ho:YAG). Damaged tissue was investigated macroscopically, histologically, and by scanning electron microscopy. Application in air caused carbonisation in all cases. Application in water showed thermal brown discoloring using Tm:YAG, Ho:YAG laser on meniscus tissue. The Nd:YAG did not ablate. The Er:YAG laser showed macroscopically precise boreholes without any discoloring of the adjacent tissue as well in meniscus as in bone. Cr:ErYSGG laser results were comparable with the results using an Er:YAG laser although ablation on bone tissue created higher thermal effects. For the aim of developing minimal invasive operating techniques the Er:YAG laser showed best results.

Animals↗

PubMed1994

A new method for practicing exploration, dissection, and simulation with a complete computerized three-dimensional model of the brain and skull.

In current practice, anatomical atlases are based on a collection of planar images presented in a book or, recently, stored on digital media. We present a new kind of interactive true three-dimensional (3D) anatomical atlases based on a volume model derived from MRI and CT. The model has a two-layer structure. The lower level is a volume model with a set of semantic attributes connected to each voxel. The semantic attributes are assigned by an anatomist using a volume editor. THe upper level represents a set of relations between these attributes. Interactive visualization tools such as multiple surface display, preparation of transparent material and cutting are provided. It is shown that the combination of this model with advanced tools for volume visualization provides the 'look and feel' of real dissection. The system therefore represents a bridge between real dissection of a cadaver and textbooks and classical atlases of anatomy. First tests have shown that the atlas system may be used successfully for teaching anatomy, but also as a reference for radiologists or surgeons. The powerful underlying data structure potentially includes all classical visual teaching aids. As a replacement of classical atlases, however, spatial resolution has still to be improved.

Anatomy↗

PubMed1994

Visualization of neonatal anatomy and pathology with a new computerized three-dimensional model as a basis for teaching, diagnosis and therapy.

A new computerized three-dimensional (3D) volume model derived from a post-mortem MRI series of the chest and abdomen of a human newborn allows interactive dissection by removing, adding organs or cutting in unlimited directions. The advanced technique of real volume visualization instead of using contours allows one to study the normal and pathological anatomy of the neonate. Anatomical details of the pleural, pericardial and peritoneal cavities and of abdominal veins are demonstrated. Compared to conventional methods, the advantages of this model for teaching and as a basis for diagnostic imaging and therapeutic procedures are evident.

Abdomen↗

PubMed1994

Ultrastructural studies on tumor capillaries of a rat rhabdomyosarcoma during fractionated radiotherapy.

Sequential morphological changes in tumor capillaries of istransplanted R1H rat rhabdomyosarcoma were observed weekly by transmission electron microscopy during fractionated radiotherapy (75 Gy/25 fractions/5 weeks). During the first 2 weeks of irradiation (up to 30 Gy), edema of the tumor capillary wall was induced. Swollen endothelial cells bulged into the vascular lumen and were surrounded by a widened subendothelial space with increase amounts of collagen fibrils (subendothelial edema). The endothelial lining was preserved up to the 3rd week of irradiation (45 Gy). Prolonged irradiation was associated with progressive destruction of the vascular wall including shrinkage, gradual loss of cell contacts, disappearance of the normal chromatin pattern, and increase of cytoplasmic vacuoles in endothelial cells as well as disruption of basal laminae. One week after the end of radiotherapy (75 Gy), the tumor capillaries showed complete necrosis. Progressive damage to tumor capillaries in the course of fractionated radiotherapy might have adverse effects on blood supply and thus on tumor oxygenation.

Animals↗

PubMed1994

[Formation of a neofascia after implantation of a composite patch in the inguinal region].

In this study, a novel patch material composed of polyglactin 910 and polydioxanon was tested in animal experiments for its use in the surgical repair of hernias. The material was implanted laparoscopically into the inner inguinal region of three hybrid running-pigs. No postoperative complications were observed. The animals were killed 14 and 48 days after surgery. Both the macroscopic and microscopic examination showed a de novo formation of connective tissue at the site of implantation, which may be regarded as a new fascia. Due to the cooperation of fibroblasts and free cells of the connective tissue, new intercellular matrix was formed after the resorption of the implanted material. A model of this cell cooperation is outlined in the study. The technical advantages of the implantation material are demonstrated and its benefits for minimally invasive surgery emphasized. Because of its special properties, the material may be recommended for later clinical traits in the surgery of fascia.

Animals↗

PubMed1993

The relative proportions of type I and type II muscle fibers in the external sphincter ani muscle at different ages and stages of development--observations on the development of continence.

The external sphincter ani muscles were partially or completely removed from 11 fetuses, 3 infants, 2 children and 12 adults, none of whom had had anorectal disease and all of whom had died of diseases not affecting the anorectal organ of continence. Muscle fiber-typing was carried out. In the fetuses ages 26-40 weeks, we found a predominance of Type II (rapid) fibers. With increasing gestational age Type II fibers started to diminish along with a simultaneous increase in Type I (slow) fibers. At the same time, stromal restructuring took place. Three infants, ages 1, 2 and 10 months, showed further increases of Type I fibers, until finally, in the two older children studied (5 and 8 years), there was a predominance of Type I fibers. This persisted in adults between ages 56 to 70, but after age 70 Type I fibers diminished, so that the ratio of slow to rapid fibers in the 78 to 81 year-old group was 3:2. This study shows that in contrast to other skeletal muscles the fiber distribution in the external sphincter ani muscle is not established from the beginning, but is the result of a developmental process. The predominance of Type II (twitching) fibers explains the state of reflex continence of the young infant. With increasing maturation of tonic Type I fibers, an additional voluntary component to continence is made possible with the help of the supporting pelvic musculature. This maturation is determined by the increasing strain on the pelvic floor as the child learns to sit and walk.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

[Autologous transplantation of rib perichondrium in treatment of deep cartilage defects of the knee joint of sheep. Morphologic comparison of two resorbable fixation methods].

The purpose of this study was to examine the fate of autologous perichondrial grafts after transplantation into cartilage lesions in weight-bearing joints, with reference to different fixation methods and different regimens of postoperative functional treatment. Full-thickness osteochondral lesions were drilled in the articular surface of knee joints in 36 sheep. The defects were filled with autologous rib perichondrial grafts, which were secured by either collagen sponges (group A; n = 12 animals) or fibrin glue (group B; n = 12 animals). Defects not filled with perichondrial grafts served as controls (group C; n = 12 animals). Following 1 week of immobilization of the treated leg, the plaster was removed and the animals were allowed to move freely. Animals were sacrificed after 4, 8, 12 and 16 weeks. The grafts were removed and investigated histologically. In contrast to weight-bearing areas and control defects, hyaline-like cartilage formation could be noted in non-weight-bearing areas after 4 weeks. This newly formed cartilage revealed strong metachromasie following staining with acidic toluidine-blue and reacted positively with PAS, indicating de novo synthesis of proteoglycans and glycoproteins. Enzyme-histochemistry for alkaline and acid phosphatase activity showed positive reactivity only at the base of the transplants. Quantitatively, hyalin-like cartilage was achieved in 40/48 transplants from the non-weight-bearing area (20/24 transplants fixated with collagen sponge (group A); and 20/24 fixated with fibrin glue (group B). In control defects only fibrous scar tissue was detectable. In transplants from the weight-bearing area only 7/48 (24 of group A and B each) a differentiation into hyalin-like cartilage was visible.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

A rabbit model for the evaluation of minimal access treatment of ectopic pregnancy in humans, using intrachorionic injection and local hyperthermia.

Rabbits at mid pregnancy were used as experimental models for investigating the feasibility of intrachorionic injection therapy in human ectopic pregnancy. Also, exposure of rabbit pregnancy to hyperthermia of 45 degrees C was studied. The experiments were followed by serial serum progesterone levels and by light as well as electron microscopy. Intrachorionic injection of different drugs led to demise in 92% of gestations. Application of hyperthermia to the pregnant rabbit uterus led in 94% to demise of gestations. Impairment of the reproductive functions after exposure did not occur. Injection was more effective up to day 15 of pregnancy, while hyperthermia had better results in older gestations. Morphological reactions to injection of different drugs and to hyperthermia were similar. Irreversible damage to the uterine wall was not observed. Intrachorionic injection of drugs may be a suitable treatment of human ectopic pregnancy. Application of hyperthermia may be a promising future therapy.

Abortifacient Agents↗

PubMed1993

[Mechanoreceptors in the distal aspects of the m. vastus medialis?].

Five cadavers were fixed in Jores' solution and alcohol. The distal parts of the medial vastus muscle and the medial parts of the patella ligament and of the capsule of the knee joint were prepared and histologically examined. Previous examinations had shown mechanoreceptors in the knee joint ligaments; the present study was designed to find whether mechanoreceptors could be identified in the anatomical structures mentioned, in which case an arthrotomy by the Payr access would interrupt the muscle reflexes. Only some mechanoreceptors in the medioventral parts of the knee joint capsule close to the tendon of the great muscle could be identified. Thus, when the Payr access is used there is no interruption of the sensibility transmitted by proprioceptors.

Adult↗

PubMed1992

[The arterial blood supply of the tibial and practical consequences].

In the periosteum of the human tibia, the arterial blood supply shows a general sectorial angioarchitecture. There are 4 segments: proximal and distal 1/5, proximal and distal diaphysis. The proximal 1/5 of the tibial periosteum is supplied with blood by the aa. recurrentes tibiales anterior et posterior and the aa. inferiores medialis et lateralis genus. At the proximal diaphysis (next 3/10 of the tibia) periosteal branches arise from the a. tibialis anterior and the a. tibialis posterior. The distal diaphysis (following 3/10 below the middle of the tibia) is nourished exclusively by semicircular rami periostales of the a. tibialis anterior, which move around the bone from both sides and join with each other at the facies medialis. It is the only sector, which is supplied by a single main artery. Concerning the periosteal blood supply of the distal 1/5 of the tibia 2 different types are found. In 2/3 of the cases the lateral side is nourished by a great vessel of the a. fibularis, which is supported by branches arising from the a. tibialis anterior. In 1/3 of the cases this vessel of the a. fibularis is absent and rami periostales of the a. tibialis anterior nourish the lateral aspect of the distal tibia alone. The dorsal region is supplied in all cases by rami of the a. fibularis and a. tibialis posterior. On the medial side the periosteal nourishment is ensured only by anastomoses. Both the facies lateralis and the facies posterior are supplied by direct branches, which arise from the main arteries of the lower leg.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

Autologous rib perichondrial grafts in experimentally induced osteochondral lesions in the sheep-knee joint: morphological results.

The purpose of the present study was to examine the fate of autologous perichondrial grafts after transplantation into cartilage lesions in weight-bearing joints. Osteochondral lesions were made in the articular surface of knee joints in 36 sheep. The defects were filled with autologous rib perichondrial grafts which were secured by either collagen sponges (12 animals) or fibrin glue (12 animals). Defects without perichondrial grafts served as controls (12 animals). Following 1 week of immobilization of the operated leg, the plaster was removed and the animals were allowed to move freely. Animals were sacrificed after 4, 8, 12 and 16 weeks. The grafts were removed and investigated histologically. In contrast to weight-bearing areas and control defects, hyaline-like cartilage formation was seen in non-weight-bearing areas after 4 weeks. This newly formed cartilage revealed strong metachromasia following staining with acidic toluidine blue and reacted positively with periodic acid-Schiff, indicating de novo synthesis of proteoglycans and glycoproteins. Scanning electron microscopy and examinations with polarized light confirmed a hyaline cartilage-like architecture for the surface area as well as for the fibre orientation of the whole graft. Enzyme histochemistry for alkaline and acid phosphatase activity showed positive reactivity only at the base of the transplants.

Animals↗

PubMed1992

[Design of a tibial intramedullary nail based on anatomic studies of intraosseous vessels].

The design of the tibial medullary nail can be improved in order to preserve intraosseus vessels by osteosynthesis of the tibia. The nutrient artery of the human tibia enters the compacta in an average height of 33% dorsally and is leaving it in a height of 50% of the tibial length. In the medullary cavity the vessel splits up. The main branch continues the distal course on the dorsal/dorsolateral side of the medullary cavity (endosteal). In the distal diaphysis this endosteal vessel is of great importance, since the periosteal blood supply in this region with high incidence of pseudarthrosis is guaranteed only by branches of the anterior tibial artery. Using a new unreamed tibial nail, which is flattened dorsally, it is possible to preserve the endostal main artery of the tibia.

Aged↗