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Biomedical subjects

C Nyssen-Behets

Publications and source records attributed to C Nyssen-Behets.

At least 19 recordsLinked to original sources
PubMed2006

Effects of irradiation on bone remodelling around mandibular implants: an experimental study in dogs.

This research focuses on the effects of radiotherapy on bone remodelling around mandibular implants in dogs. After bilateral extraction of the mandibular premolars and first 2 molars, each of 11 beagles received 8 mandibular implants. Four animals were irradiated 4 weeks after implantation and 4 others 8 weeks before implantation; the remaining 3 did not receive radiotherapy. Irradiation consisted of 10 daily fractions of 4.3Gy (60)Co. Fluorochromes were given at implantation and irradiation to allow the measurement of bone apposition. The dogs were killed 6 months after implantation. Each hemi-mandible was processed according to bone-specific histological techniques. New bone formation was visible around 85 of the 88 implants. Stimulated mandibular remodelling was attested in both irradiated groups by increased porosity and numerous labelled osteons. Resorption was more pronounced in the group irradiated after implantation, but osteon formation appeared unvarying. Osseointegration was thus shown to be compatible with bone irradiation as bone turnover activities were maintained throughout the experiment. As the apposition stage of the remodelling cycle appears crucial to achieve optimal osseointegration, its normal completion should be taken into account in clinical practice by respecting a 6-month period between irradiation and implantation.

Animals↗
PubMed2005

The deep belly of the temporalis muscle: an anatomical, histological and MRI study.

In order to achieve a better functional and clinical knowledge of a masticatory muscle called the sphenomandibularis that is suspected to be responsible for headaches by compressing the maxillary nerve, bilateral dissections of the infratemporal fossa were performed on ten human cadavers and completed by histological and radiological studies of the same areas. Both macroscopic and microscopic observations obviously showed that the so-called sphenomandibularis muscle corresponds to the deep portion of the temporalis muscle, since there is no epimysial septum between these two structures, which previously have been described as being completely independent from each other. In spite of the close topographic relationship between the deep belly of the temporalis and the lateral pterygoid muscle, as well as their similar innervation pattern, the sphenomandibularis in fact has to be considered functionally as an original but non-isolated positional fascicle of the temporalis muscle itself. Our observations, correlated with MR images, suggest indeed that the deep belly of the temporalis muscle is of functional importance in the masticatory movements, but is not involved by its neurovascular vicinity in the genesis of specific headaches. Its surgical release, however, should be discussed in the case of a temporal myoplasty.

Aged↗
PubMed1998

Postmenopausal osteoporosis: microradiographic aspects.

A comparative microradiographic and histologic analysis of undecalcified bone samples was performed in men and women aged 18-98 years. These morphological methods showed that besides usual lamellar bone remodelling, all the so-called inert surfaces, namely both haversian and vascular canals as well as trabecular surfaces, were involved in weathering alterations of the superficial lamellae, resulting in eroded outlines devoid of osteoclast. These aspects, recorded in all pieces of our material, were visible from the earliest adult age and were randomly distributed. Except the grade of osteoporosis at a given age, the microradiographic and histologic aspects were similar in both aged men and women and did not allow sex distinction. These observations were consistent with the hypothesis of a particular destructive process affecting all the quiescent lamellar bone surfaces without osteoclast or cell participation. This kind of erosion, termed delitescence, could be at least partially responsible for the age-related and postmenopausal bone loss. In order to explain the increasing osteoporosis after menopause, it has been suggested that the estrogen deficiency could increase the percentage of dead osteocytes. Thereby the reduced cellular control on the bone surface could impair the remodeling process and fail to adapt the bone structure by repairing the microscopic lesions.

Adolescent↗
PubMed1997

Structural changes with aging in cortical bone of the human tibia.

Structural modifications are considered to play a significant role in the age-related alterations of bone quality and strength. Senescent compact bone is characterized by an increasing heterogeneity of aspects, including high numbers of lowly mineralized osteons as well as the presence of osteons with hypermineralized lamellae or with a notched haversian canal wall, and of double-zone osteons. These latter three types of osteons are different from the structures involved in the haversian remodeling. In the present study, blocks of midshaft tibia from 7 young men (18-39 years), 14 aged men (50-92 years) and 15 aged women (57-96 years) were embedded in methyl methacrylate in order to perform microradiographic and histomorphometric analysis of undecalcified sections. The intracortical porosity was higher in the aged men than in the young ones, as were the numbers of haversian structures and, to a lesser extent, the diameters of the haversian canals. The aged women showed the same tendency, with cortical porosity still higher than in the men. The osteons with hypermineralized lamellae, those with a notched canal and the double-zone osteons appear to constitute large subgroups of the total haversian population, even in the early adult life. Among them, only the osteons with a notched canal wall increased in frequency with age. The 3 types are much more numerous than the structures involved in the typical haversian remodeling. The correlations between their frequencies as well as their significant topographic association corroborates the hypothesis that the hypermineralized lamellae may crumble down because of their excessive brittleness, giving rise to the haversian canals with notched walls. These enlarged canals could be refilled by bone apposition and result in the double-zone osteons. The 3 types of osteons could constitute different steps of one mechanism of bone desintegration and repair occurring very progressively, which might contribute to modify the bone quality and to increase the intracortical porosity.

Adolescent↗
PubMed1996

Aging effect on inductive capacity of human demineralized bone matrix.

Demineralized bone powder (DBP) prepared from human cortical bone was implanted into subcutaneous pouches of athymic Nu/Nu mice for 28 days. The osteoinductive capacity was evaluated by histomorphometry of the induced cartilage and bone, and by alkaline phosphatase activity in the implant. Very small amounts of new bone and cartilage were found at histological analysis, confirming that human DBP is much less osteoinductive than that from other species. Whereas the morphometric data of the implants from the young and aged donors were not significantly different, the alkaline phosphatase activity was significantly lower in the implants from the old donors than from the younger ones. This difference between the morphometric and biochemical results could reflect the fact that the enzymatic activity is already present in the osteoprogenitor cells. At 28 days, the osteoblastic activity in contact with DBP from the aged group is characterized by a decrease in the enzymatic amount which is not yet visible at the tissue level. This tendency to a decrease in the osteoinductive capacity of bone matrix is an additional aspect of the age-related alterations which occur in bone tissue and could be attributed to modifications of different proteins of the bone matrix, including bone morphogenetic protein.

Aging↗
PubMed1996

A new familial short stature syndrome: Brussels type.

A new association of congenital familial short stature with facial dysmorphism and osteochondrodysplastic lesions is described in two siblings. Clinical abnormalities include severe prenatal and postnatal growth failure and facial dysmorphism. Radiographs show osteochondrodysplastic lesions with a narrow thorax, short ribs, epiphyseal maturation delay and slightly deformed metaphyses. Microscopic analysis of the skeleton shows pathological features.

Body Height↗
PubMed1995

Cancellous bone in human acetabulum: microradiographic and histomorphometric aspects.

The acetabular cancellous bone of 18 subjects aged 57-88 years was characterized by low mass and a poorly ramified pattern according to microradiographic analysis. There was no correlation between the histomorphometric data of this region and those of the iliac crest. Microcalluses were visible in 13 acetabular samples, whereas they were absent from the iliac crest. As the acetabular trabeculae appeared decidedly longitudinal, age-related bone rarefaction is suggested to occur in two different ways: uniform thinning of the trabeculae and selective disappearance of transverse elements. The remaining longitudinal trabeculae are considered to be most useful for the weight-bearing function of the hip joint.

Acetabulum↗
PubMed1995

Microradiography and fluorescence microscopy of bone remodeling on the basal crypt of permanent mandibular premolars in dogs during eruption.

Alveolar bone of erupting teeth was studied in order to define the types of calcified tissues deposited as well as the rate of tooth growth. The third (P3) and fourth (P4) mandibular premolars of 30 dogs aged 12-24 weeks were analyzed by microradiography and microscopy in fluorescent and ordinary light. The bone plate separating P3 and P4 from the mandibular canal presented a complex arrangement of lamellar and woven bone, and even of chondroid tissue. During the pre-eruptive phase, this plate shifted towards the base of the mandible by means of selective resorption and apposition activities. As soon as the furcation was formed, bone apposition appeared on the alveolar side and became the main activity under P3 at the outset of eruption. Under the roots of P4 it occurred 4 weeks later. Dynamic morphometry in fluorescence microscopy showed that eruption progressed faster than the radicular growth. The formation of interradicular bone underwent the same acceleration as the eruption. However, though the tissues were formed at a high rate, it cannot be inferred therefrom that they are responsible for tooth shifting. They might just fill the space left by the erupting tooth.

Alveolar Process↗
PubMed1992

Ossification of the human fetal ilium.

Ossification of the ilium is similar to that of a long bone. It possesses three cartilaginous epiphyses and one cartilaginous process. Moreover, it undergoes peculiar osteoclastic resorption, comparable with that of the cranium bones. Asymmetrical ossification of the ilium, haversian bone remodelling and apposition of chondroid tissue posterosuperiorly to the acetabulum most probably emphasize the importance of mechanical factors in the morphogenesis of the hip bone during fetal life.

Fetus↗
PubMed1992

The fate of the quiescent surfaces of lamellar bone.

Microradiographic and histologic analysis of undemineralized bone was performed in 62 subjects aged 18-97 years. Ten of these samples were also submitted to scanning electron microscopy. Besides the usual lamellar bone remodeling, all types of bone surfaces, namely both haversian and vascular canals and the endosteal and trabecular surfaces, were involved in weathering alterations of the superficial lamellae, resulting in eroded outlines, less deeply notched than the Howship lacunae and devoid of osteoclast. Present as soon as early adult life and randomly distributed, these aspects were recorded in all the bone pieces examined. These observations were consistent with the hypothesis of a particular destructive process in all the quiescent lamellar bone surfaces without osteoclast participation, termed delitescence, which could be partly responsible for age-related bone loss.

Adolescent↗
PubMed1992

Increased resistance to artificial caries-like lesions in dentin treated with CO2 laser.

The crowns of 60 permanent human molars were sectioned transversally. The exposed dentin surface was divided into different parts: a first part was kept as control, a second part was immediately varnished, and a third part was irradiated with a CO2 laser using the same irradiation conditions as those applied for caries removal (10 impulses of the same energy; 0.2 s/impulse; energy density/impulse 280-715 J/cm2. After irradiation, a small portion of this area was varnished. The teeth were immersed for 4 weeks in a cariogenic gel (pH = 4.5) at 36 degrees C. Twenty teeth were studied by scanning electron microscopy, and longitudinal sections of the other teeth were prepared for microradiography and microdensitometry measurements. The lased dentin surface appeared smooth for energy densities lower than 425 J/cm2. Longitudinally fractured samples revealed a layer of dentin devoid of tubular structure (20-70 microns thick, depending on the energy density used), whereas below the sealed layer, the dentinal tubules retained their normal aspect. Although the sealed layer showed no demineralization when exposed to acid, demineralization of the underlying dentin occurred, but to a much lesser extent than in the unlased dentin.

Carbon Dioxide↗
PubMed1991

Long-term sequelae of pelvis irradiation: histological and microradiographical study of a femoral head.

Despite the lack of radiological signs, a femoral head showed histological and microradiographical features of osteonecrosis, 54 years after massive irradiation of the right hip. Intertrabecular spaces were invaded by connectivo-vascular tissue with focal accumulation of mast cells, and several resorption foci were filled with mononucleated cells. Moreover, all the microradiographs showed peculiar hypercalcified lines, sometimes containing empty osteocytic lacunae, the origin of which is difficult to precise. This study suggests that massive irradiation of weight-bearing epiphyses may be responsible for particularly long-term hypovascularity, osteonecrosis and disturbed bone remodeling.

Female↗
PubMed1991

[Histomorphometry and photodensitometry of osteons with hypercalcified ring of human compact bone].

Osteons with hypercalcified ring were measured by photodensitometry and histomorphometry in the tibial diaphysis of 20 male and female subjects died from 23 to 93 years, the age-related decrease of cortical bone volume corresponded to wide Haversian canals. However, the osteons with a hypercalcified ring had a narrow canal. Moreover, the radio pacity of the hypermineralized ring was 20 to 30% higher than the adjacent parts of the osteon and the central part was nearly never less mineralized than the peripheric one. So the hypercalcified ring did not appear to be an arrest line. It may be suggested that it constitutes a sign of cortical bone senescence.

Absorptiometry, Photon↗
PubMed1989

Physical and histomorphological characteristics of iliac crest bone differ according to the grade of osteoarthritis at the hand.

The amount of cortical and trabecular bone was studied in 32 iliac crest necropsy specimens from women 60-75 years of age and examined according to the grade of osteoarthritis. Three different methods to evaluate bone mass were used: dual photon absorptiometry, physical assessment according to Archimedes' principle, and histomorphometry. Patients were divided into groups--with or without osteoarthritis--according to the presence of osteoarthritis on hand x rays. A significantly increased amount of cortical and trabecular bone mass was found in those who had osteoarthritis at the hands. Percent pure/crude bone volume and trabecular width were found to be increased with osteoarthritic grade, indicating that primary osteoarthritis is probably part of a generalized bone disease.

Absorptiometry, Photon↗
PubMed1989

Haversian bone remodelling in human fetus.

Haversian bone remodelling used to be considered an attribute of adult bone. In the present paper, typical haversian remodelling was observed in the humerus, ulna, radius, femur, tibia, fibula and 6th and 7th ribs as soon as the 24th week. Its aspect suggests an already ancient occurrence. Remodelling was found in the same bone pieces of the neonate as well as in the clavicle and the other ribs. Mechanical factors may be responsible for starting the remodelling but their effects could be modulated by metabolic needs. Other still unknown factors might play a role too.

Bone Development↗
PubMed1989

Biomechanical characteristics of iliac crest bone in elderly women according to osteoarthritis grade at the hand joints.

Postmortem iliac crest trabecular bone specimens were tested in compression to determine their mechanical characteristics. Trabecular bone volume and width were evaluated by histomorphometry and radiographic grading of osteoarthritis (OA) of hand joints was also done. Patients were divided into 2 groups: no or low grade OA (Group 1) and manifest OA Grades II-IV (Group 2). From the 27 specimens tested (women 56-80 years old), 17 were in Group 1 and 10 in Group 2. Significant differences in stiffness (E), compressive strength, trabecular bone volume and trabecular width between the 2 groups were found. In the group with manifest OA, bone was significantly stiffer, had a significantly increased compressive strength value, a significantly higher trabecular bone volume and trabecular width, compared to the group with no or low OA grade. Significant correlations were found between elastic modulus and trabecular bone volume and width, and also between compressive strength and trabecular bone volume and width. Our findings support the hypothesis that the primary defect in OA is not in the articular cartilage but in the subchondral bone and that primary OA is part of a more general bone disease.

Aged↗
PubMed1989

Microradiographic study of bone and tooth alterations in bovine fluorosis.

Exostoses were found in the 5th rib, the cannon bone and the mandible of a 6-year-old fluorotic cow. Microradiographic alterations of lamellar bone in these skeletal items included both matrix modifications and mineralization troubles. In the incisors, the enamel was covered by a layer of cementum, and the dentine presented numerous giant tubules and accentuation of incremental lines. In the cementum, hypomineralized areas were located along the periodontal fibres.

Animals↗