Biomedical subjects

D Chappard

Publications and source records attributed to D Chappard.

At least 37 records · Page 2Linked to original sources

PubMed1998

Cytomorphometric analysis of vaginal cells during normal cycle, under oral contraceptive therapy or in-vitro fertilization stimulation protocol.

A cytomorphometric analysis of superficial vaginal cells in women in three groups of different types of hormonal concentration was made. There were 15 women in each group. Group I was studied during a natural cycle, group II under oral contraceptive therapy and group III during an in-vitro fertilization (IVF) stimulation protocol. Morphometric parameters were measured on an image analyser. The area, perimeter and several form factors were measured separately for nuclei and cytoplasm. The nucleus:cytoplasmic ratio was also determined. The cytoplasmic area was significantly reduced in group II and was associated with a statistically significant reduction of the nuclear area. The nucleus:cytoplasmic ratio appeared significantly increased in group II and reduced in group III. Low oestradiol impregnation obtained with an oral minidosed contraceptive interfered with vaginal cell maturation. High oestradiol concentrations obtained during IVF protocols induced marked nuclear pycnosis but did not induce supra-physiological cell enlargement. Maximal cell size is genetically regulated according to Driesch's law of volume invariance and hormonal over-stimulation has no effect on cell size. The nucleus:cytoplasmic ratio appears to be a powerful parameter reflecting the opposite effects of hormones on cell compartments.

Adult↗

PubMed1997

Sex-related C cell hyperplasia in the normal human thyroid: a quantitative autopsy study.

We report a prospective quantitative image analysis study of C cells in 57 normal autopsy thyroid glands, serially sectioned and wholly embedded in paraffin; all slides were immunohistochemically stained for calcitonin. Computerized quantitative image analysis was performed on 47 cases to measure C cell surface area and parenchymatous surface area after immunoperoxidase staining for calcitonin. The method was time-effective, with a good reproducibility. C cells were mainly found in the middle third of each lobe. Important inter-individual variations were observed; the maximum C cell surface area in a section (Amax) ranged from 28 x 10(3) to 470 x 10(3) microns2 (mean, 167 x 10(3) microns2) among 42 adults. Of particular interest was the important difference observed between sexes; Amax was twice as high in men (mean, 201 x 10(3) microns2) as in women (mean, 91 x 10(3) microns2; P = 0.0009). Moreover, 14 (33%) adult subjects [2 women (15%) and 12 men (41%)] fulfilled C cell hyperplasia criteria, i.e. at least 3 fields at x 100 magnification containing more than 50 C cells, suggesting that a substantial part of the normal adult population could have C cell hyperplasia.

Adult↗

PubMed1996

Expression of prolactin receptors in human osteosarcoma cells.

The expression of prolactin receptor (PRL-R) mRNA was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) combined with Southern analysis in total RNA extracts from two human osteosarcoma cell lines (MG-63 and Saos-2). The level of PRL-R transcript was significantly enhanced in cells cultured in the presence of 1,25-(OH)2 vitaminD3 (10(-7)M) and to a lesser extent in the presence of dexamethasone (10(-6)M). This first demonstration of PRL-R gene expression in osteoblast-like cells supports the hypothesis of a direct action of prolactin in bone cells, which is further strongly suggested by the stimulatory effect of 1,25-(OH)2 vitaminD3 and dexamethasone on PRL-R mRNA level in these cells.

Bone and Bones↗

PubMed1996

Quantifiable excess of bone resorption in monoclonal gammopathy is an early symptom of malignancy: a prospective study of 87 bone biopsies.

To determine if excessive osteoclastic-mediated bone resorption (BR) is an early tumor-induced event in multiple myeloma (MM), BR was assessed at first presentation on quantitative bone biopsy in 87 individuals evaluated for monoclonal gammopathy of undetermined significance (MGUS) and reinterpreted according to the presenting features and subsequent follow-up evaluation. As a reference population, 48 patients with previously untreated overt MM were evaluated under similar conditions. The median level of BR was significantly higher in 48 overt MM versus 87 MGUS patients (12.2% v 5.1% [normal level, <6%], P <.01). Actually, 93% of overt MM patients had an excessive BR versus 45% of MGUS patients at presentation (P <.01) According to simple presenting parameters (> or <5% plasma cells within the bone marrow, presence or absence of mild anemia/neutropenia), 31 individuals were classified as low-risk MGUS, 32 high-risk MGUS, and 24 indolent MM. An excessive BR was observed in 16% of low-risk MGUS, 46% of high-risk MGUS (P <.01 v low-risk MGUS), 79% of indolent MM (P <.05 v high-risk MGUS), and 93% of overt MM patients. Of major interest, the level of BR in indolent MM (11.2%) was identical to that in overt MM (12.2%) but significantly higher than in both low-risk (4%, P <.01) and high-risk (5.6%, P <.01) MGUS. When considering the follow-up evaluation of MGUS patients, an excessive BR at presentation was observed in 52% of MGUS cases that turned out to be unstable or developed subsequent MM, but in only 4% of stable MGUS (P <.01). More precisely the level of BR of low-risk MGUS that either turned out to be unstable or that developed into MM was significantly higher at presentation than that of subsequent stable MGUS (4.4% v 2.9%, P <.05). The same difference was observed in both high-risk MGUS and indolent MM according to subsequent follow-up studies (8.1% v 3.4% and 11.7% v 6%, respectively, P <.05). Of major interest, the level of BR in 11 stable high-risk MGUS cases actually fulfilling the diagnostic criteria of smoldering MM was very low (3.4%) and similar to that in stable low-risk MGUS (2.9%). We conclude that a quantifiable excess of BR in MGUS is significantly associated with progression and thus is an early symptom of malignancy in these individuals.

Anemia↗

PubMed1996

[Viral origin of Paget's disease of bone?].

The viral aetiology of Paget's bone disease was suspected by the finding, in 1974, of microcylindric paramyxovirus nucleocapsid-like inclusions in nuclei and cytoplasm of pagetic osteoclast. Paramyxovirus antigens were detected, using monoclonal antibodies, in the osteoclasts of pagetic lesions. Paramyxovirus RNA sequences were identified in Paget's bone tissue, predominantly in osteoclasts, using specific hybridization. However, these last results are conflicting because some reports failed to reproduce hybridization with Paramyxovirus. Nevertheless, Paramyxovirus could be responsible for the cytopathologic aspect of multinucleated osteoclasts for the stimulation of hyperexpression, in Paget's disease, of interleukin 6 and of c-fos oncogene known to enhance osteoclastic resorption activity.

Humans↗

PubMed1996

Migration of metal and polyethylene particles from articular prostheses may generate lymphadenopathy with histiocytosis.

Wear particles released from hip or knee prostheses are known to be involved in the fibrohistiocytic membrane interposed between bone and implant. During surgical treatment for pelvic carcinoma (5 cases) and for isolated pseudomalignant lymphadenopathy (4 cases) lymph nodes in 9 patients who had had lower limb articular replacement were harvested. Light microscopy and image analysis of the nodes showed florid endosinusal histiocytosis, predominant in the cortical area. Using Oil Red O staining and polarized light, metal particles and polyethylene particles were detected in the large histiocytes. Scanning electron microscopy with electron backscattering allowed us to localize metal particles and perform elemental microanalysis. Iron, cobalt, chromium, nickel, zirconium, and barium, known to be used in prosthetic and cementing materials, were identified as component of these particles. Large amounts of polyethylene particles appeared in all cases while metal particles were found to be abundant in only 2 cases. Thus, migration of polyethylene debris from the prosthetic site seems to be the major factor in development of the histiocytes induced in satellite lymph nodes.

Aged↗

PubMed1996

Evolution of the bone-titanium interface on implants coated/noncoated with xenogeneic bone particles: quantitative microscopic analysis.

Titanium cylinders having a sandblasted surface were implanted in holes drilled in the internal condyles of rabbit femurs. The right side received a titanium implant coated with xenogeneic bone particles and the left side received a titanium cylinder alone and was used as control. The femoral extremities were removed at 1, 2, and 3 months postsurgery and embedded undecalcified in methacrylic resins. Sections were studied by quantitative analysis and the interface contact between bone and titanium was measured at two microscopic magnifications due to the fractal dimension of this parameter. In addition the amount of bone volume in a given referent volume provided automatically by the image analyzer was obtained. No differences could be evidenced between the two series of implants, supporting the view that xenogeneic particles were ineffective in improving the attachment of bone to the implant. The bone-to-implant interface measured at the low magnification reflected the anchorage of the implant. In both series a progressive increase upon time of the bone-to-implant interface at the highest microscopic magnification evidenced the importance of late remodeling changes responsible for bone bonding and the fractal characteristics of this interface, related to surface quality of the implant responsible for stress transfer.

Analysis of Variance↗

PubMed1996

Altered trabecular architecture induced by corticosteroids: a bone histomorphometric study.

Prolonged corticosteroid (CS) therapy induces osteoporosis and fractures. Osteoporosis is characterized at the histomorphometric level by reduced bone volume (BV/TV) and disruption of the three-dimensional (3D) trabecular architecture. Several stereological methods have been proposed to characterize these alterations: measurements of trabecular thickness and trabecular number, star volumes, interconnectivity index (ICI) of the bone marrow spaces, and trabecular bone pattern factor (TBP(f)). These methods were computerized with a single program running on an image analyzer to evaluate the bone changes in a series of iliac biopsies performed on 31 male patients. All of them were asthmatic and had received CS for a long period of time. BV/TV was reduced when compared with age-matched controls. In the CS-treated population, exponential relationships were obtained between bone volume and the different connectivity parameters. The various methods used to measure connectivity were well correlated. When the population was divided into two groups (BV/TV greater or less than an 11% threshold), the architectural disturbances were found to imply two mechanisms. A progressive decline in trabecular thickness was noted in both groups versus controls. Trabecular perforations were not established in the group with BV/TV> 11% with the star volume or ICI, although some alterations were detected by trabecular bone pattern factor measurement. However, perforations were revealed in the group with BV/TV < 11% by all the different methods. Perforations seemed to occur when the trabecular thickness was below 70 mu m. This strongly suggests that bone histomorphometry should take into consideration bone volume in combination with detailed 3D descriptors of the trabecular architecture. Several histological methods need to be used in combination to appreciate the 3D architecture of trabecular bone.

Adrenal Cortex Hormones↗

PubMed1996

Spontaneous multiple vertebral fractures revealed primary haemochromatosis.

The association of haemochromatosis and bone disease is well established, but osteoporotic fracture is an unusual presentation of the disease. We describe a male patient with osteoporotic fractures as a presenting feature of haemochromatosis. The bone histomorphometry showed a dramatic decrease in trabecular bone volume associated with a decrease in cortical bone thickness. Osteoblastic and osteoclastic activities were reduced without any sign of osteomalacia. Staining for iron with Perl's stain showed focal localization at the interface between mineralized trabecular bone and bone marrow. This observation leads us to review the possible mechanisms of osteoporosis.

Hemochromatosis↗

PubMed1996

Osteoclast cytomorphometry in patients with femoral neck fracture.

In patients with femoral neck fracture, nutritional deficiencies have been shown to be common. A low calcium diet and/or a reduced vitamin D intake have been suspected to cause secondary hyperparathyroidism responsible for increased bone turn over and bone loss. Parathyroid hormone (PTH) levels are increased in these patients, data which are in accordance with the pronounced changes observed on bone biopsies reflecting a true hyperparathyroidism. We have used a cytomorphometrical approach to characterize PTH-induced changes on the osteoclastic population. Osteoclasts were detected histochemically (by tartrate resistant acid phosphatase staining) on bone biopsies from 10 control subjects, 8 patients with primary hyperparathyroidism and 10 patients with a femoral neck fracture of osteoporotic origin. The maximum Feret's diameter of each osteoclast (Oc.Le) was determined with a semiautomatic image analyzer. In all groups, the frequency distribution of Oc.Le appeared positively skewed. In both hip fractured patients and primary hyperparathyroid patients, the mode of the distribution was higher (25-30 microns) than in controls (20-25 microns). When graphically converted on a probability graph, the osteoclastic populations appeared homogeneous and well described by a lognormal distribution in the three groups. However, osteoclasts appeared similarly enlarged in the groups of patients with primary hyperparathyroidism and with femoral neck fracture. PTH has been shown to increase both the recruitment of mononucleated precursors and their fusion into larger osteoclasts than controls. In the present study, a cytomorphometric method appeared able to identify the border line hyperparathyroidism in the hip fractured patients.

Adult↗

PubMed1995

Effects of tiludronate on bone loss in paraplegic patients.

Immobilization secondary to spinal cord injury is associated with a marked and rapid atrophy of trabecular bone (disuse osteoporosis). This is due to an early increase of osteoclastic bone resorption associated with a pronounced decreased osteoblastic bone formation. Bisphosphonates are antiosteoclastic compounds and they have been effective in preventing disuse osteoporosis. However, some of them also depress osteoblastic activity and may impair the mineralization process. Tiludronate was shown effective in reducing bone resorption in several metabolic bone diseases without inducing mineralization defects. Twenty paraplegic patients (6 females and 14 males) were randomly assigned to three groups: 6 patients entered the placebo group; 7 patients received tiludronate 200 mg/day; and 7 received 400 mg/day. Histomorphometric analysis was performed on transiliac bone biopsies before and after 3 months treatment. An insignificant decrease of bone volume was observed in the placebo group and the 200 mg group. In patients receiving 400 mg/day, a slight increase was noted. Osteoid parameters changed nonsignificantly in three groups although the 400 mg group exhibited a slight tendency to decrease osteoid volume and thickness. Eroded surfaces increased in all groups. The number of osteoclasts (identified histochemically by TRAP staining) increased in the placebo group but decreased in groups receiving tiludronate. Tiludronate appears effective in reducing bone resorption without impairing bone formation in a manner that preserved bone mass and bone cell coupling.

Adolescent↗

PubMed1995

Excessive bone resorption in human plasmacytomas: direct induction by tumour cells in vivo.

We studied the bone resorption (BR) in 82 patients with overt plasmacytomas (PCT) by histomorphometry. All the solitary PCT and 90% of overt PCT in complete remission lacked excessive BR. In contrast, 73% of the 68 patients with active overt PCT had an excessive BR. This excessive BR was highly related to the presence of tumour cells within the bone sample. Indeed, 92% of patients with active PCT and tumour cells within the biopsy had an excessive BR. On the other hand, 70% of patients with active PCT but lacking tumour cells within the biopsy had normal BR.

Aged↗

PubMed1994

[Male osteoporosis].

Careful examination as well as biochemical and hormonal investigations should be performed in men suffering from vertebral crush fractures, in order to detect a destructive skeletal process (multiple myeloma, bone metastatic lesions, lympho and myeloproliferative disorders), a mineralization defect (osteomalacia) or a secondary osteoporosis: primary hyperparathyroidism, hypogonadism, hyperthyroidism, renal hypercalciuria, alcoholism and tobacco smoking. The diagnosis of idiopathic osteoporosis should be made only after these causes have been excluded; the pathogenesis of the disease is unclear but risk factors have been identified: family history of osteoporosis, low dietary calcium intake, delayed puberty, ethanol use, tobacco smoking, inactive lifestyle and lean body build. Correction of risk factors, calcium supplementation, regular program of weight bearing physical activity, in some instances correction of testosterone deficiency may be of benefit to reduce bone loss. Severe osteopenia or osteoporosis may require sodium fluoride therapy.

Absorptiometry, Photon↗

PubMed1994

Bone histomorphometry in 50 normal Tunisian subjects.

Quantitative bone histomorphometry was done on undecalcified sections of iliac crest bone specimens obtained at autopsy from 50 normal subjects (24 males and 26 females). The following parameters were measured: cortical thickness (Ct.Th), trabecular bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), osteoid volume (OV/BV), osteoid surfaces (OS/BS), osteoid thickness (O.Th) and eroded surfaces (ES/BS). There was a significant age-related decrease in BV/TV in both sexes which followed a x3 polynomial regression. A significant decrease of Tb.Th was noted in males after the fifth decade. In males, bone loss was 1.5% per decade, but in females it was 0.36% before menopausal period and 2% after. Other parameters were unrelated to age and sex.

Adolescent↗

PubMed1994

[Electron microscopic study of a macroporous calcium phosphate ceramic implanted in an osseous site].

Cellular and tissular responses to intraosseous graft of a macroporous calcium phosphate ceramic was studied using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Twelve specimens were implanted in 6 rabbits (tibiae), taken at day 14 after implantation and processed either for TEM (6 samples) or SEM (6 samples). As early as day 14 after implantation osteogenesis so that resorption of the newly formed bone and of the biomaterial, were observed at the surface of the ceramic, inside the macropores. Osteoblasts were clearly visible and well differentiated with abundant rough endoplasmic reticulum and large Golgi zone. The resorption processes were associated with 2 types of multinucleated cells. Based on ultrastructural observations (cellular characteristics and measurement of the microporosity) it appears that incompletely differentiated osteoclast was the major cell responsible of the biodegradation of the ceramic. These results suggest that the cellular events occurring at the surface of a macroporous calcium phosphate ceramic are similar to that observed in physiological bone remodelings.

Animals↗

PubMed1993

Osteoclastic resorption of Ca-P biomaterials implanted in rabbit bone.

The nature of the multinucleated cells involved in the resorption processes occurring inside macroporous calcium-phosphate biomaterials grafted into rabbit bone was studied using light microscopy, histomorphometric analysis, enzymatic detection of tartrate-resistant acid phosphatase (TRAP) activity, scanning, and electron microscopy. Samples were taken at days 7, 14, and 21 after implantation. As early as day 7, osteogenesis and resorption were observed at the surface of the biomaterials, inside the macropores. Resorption of both newly formed bone and calcium-phosphate biomaterials was associated with two types of multinucleated cells. Giant multinucleated cells were found only at the surface of the biomaterials; they showed a large number of nuclei, were TRAP negative, developed no ruffled border, and contained numerous vacuoles with large accumulation of mineral crystals from the biomaterials. Osteoclasts exhibited TRAP positivity and well-defined ruffled border. They were observed at the surface of both newly formed bone and biomaterials, around the implant, and inside the macropores. In contract with the biomaterials, infoldings of their ruffled border were observed between the mineral crystals, deeply inside the microporosity. The microporosity of the biomaterials (i.e., the noncrystalline spaces inside the biomaterials) increased underneath this type of cell as compared with underneath giant cells or to the depth of the biomaterials. These observations demonstrate that macroporous calcium-phosphate biomaterials implanted in bone elicit osteogenesis and the recruitment of a double multinucleated cell population having resorbing activity: giant multinucleated cells that resorb biomaterials and osteoclasts that resorb newly formed bone and biomaterials.

Animals↗

PubMed1993

Fat in bone xenografts: importance of the purification procedures on cleanliness, wettability and biocompatibility.

Xenografting is a promising alternative to allografts and autografts. The remaining lipids in bone are known to influence the biocompatibility. A comparative study of wettability was done on standardized blocks of two biomaterials. A highly purified and defatted bovine bone graft (T650) was found to retain more water (2.06 g/block) than a less defatted biomaterial (T360, 0.3 g/block). Wettability, observed in the laboratory, may reflect an important in vivo property: the rapidity for extracellular fluids and blood cells to invade the graft and carry bone forming cells. When implanted in rabbit cancellous bone, T650 appears to be osteoconductive in a manner that allows trabecular architecture to be restored within 6 months.

Animals↗

PubMed1993

[Biomaterials for bone filling: comparisons between autograft, hydroxyapatite and one highly purified bovine xenograft].

Bone grafts are becoming increasingly common in orthopaedics, neurosurgery and periodontology. Twenty one New Zealand rabbits were used in the present study comparing several materials usable as bone substitutes. A 4.5 mm hole was drilled in the inner femoral condyles. Holes were filled with either an autograft (from the opposite condyle), an hydroxylapatite (Bioapatite), or a highly purified bovine xenograft (T650 Lubboc). Animals were sacrificed at 1, 3 and 6 months post implantation and a quantitative analysis of newly-formed bone volume (BNF/IV) and remaining biomaterials (BMAT/IV) was done. In addition, some holes were left unfilled and served as controls. At 6 months, there was no tendency for spontaneous repair in the control animals. The autografted animals have repaired their trabecular mass and architecture within the first month. Hydroxylapatite appeared unresorbed at six months and only thin and scanty new trabeculae were observed. The xenograft induced woven bone trabeculae formation on the first month. This was associated with resorption of the material by two multinucleated cell populations. At six months, the epiphyseal architecture was restored and the biomaterial has disappeared in most cases. Xenografts appear a promising alternative to autografts and allografts, whose infectious risks and ethical problems should always be borne in mind.

Animals↗