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Biomedical subjects

D Chappard

Publications and source records attributed to D Chappard.

138 records · Page 8Linked to original sources
PubMed1979

Colored filters for microphotography: a costless 'do-it-yourself' solution.

Black and white microphotography makes use of several colored filters for an increased contrast. These filters are sometimes expensive and do not correspond exactly to the stain to be masked on the negative. Our specific colored filters contain a sufficient and adjusted amount of the dye used in the staining technic in an Agar medium.

Agar↗
PubMed1977

[Nucleo-cytoplasm ratio, DNA content of superficial and intermediate vaginal cells during the female genital cycle].

A quantimetric study of vaginal superficial cells is done every day of the sexual cycle on five normal women (no pill) with a cervical smear of type 2 (Papanicolaou classification). Our results show that nucelo-cytoplasmic ratio for 98% of the cells varies between 0.0040 and 0.0210. This level is independant of age and cycle duration and is proposed as reference for later studies of women under pill or with cervico-vaginal dysplasia and cancer.

Adult↗
PubMedDate not supplied

Comparison of eight histomorphometric methods for measuring trabecular bone architecture by image analysis on histological sections.

Osteoporosis is defined as a disease characterized by low bone mass and microarchitectural deterioration of trabecular bone leading to enhanced bone fragility. Various histomorphometric methods have been described to measure bone architecture on histological sections. However, not all of the methods are strictly equivalent and some of them appear able to detect differences earlier in the course of the disease. We have compared 8 histomorphometric methods known to characterize the architecture of trabecular bone in 154 male osteoporotic patients. Measurements were done on transiliac bone biopsies: Trabecular number, thickness, and separation (Tb.N, Tb.Th, Tb.Sp); Trabecular Bone Pattern Factor (TBPf); Euler-Poincare's number (E); Interconnectivity Index (ICI); strut analysis of the trabecular network with the ratio of nodes/free-end (N/F); star volume of the bone marrow (V*m.space) and trabeculae (V*Tb) and the Kolmogorov fractal dimension of the trabecular boundaries (D). Relationships between the various architectural parameters were studied by hierarchical cluster analysis. Linear, hyperbolic, and exponential correlations were found between trabecular bone volume (BV/TV) and architectural parameters. Cluster analysis demonstrates the link between these architectural parameters. ICI, E, and TBPf, which reflect the amount of open/closed marrow cavities clustered together and appeared related to Tb.Sp, V*m.space which are indicators of the mean size of marrow cavities. Tb.Th, V*Tb and N/F flocked together as they reflect the trabecular size. Tb.N and D segregated together and seemed to best describe the trabecular network complexity. These histomorphometric techniques are correlated but correlations may be linear or nonlinear. Several histomorphometric techniques need to be used in parallel to appreciate the pathophysiological mechanisms of osteoporotic states.

Adult↗
PubMedDate not supplied

Enhanced bone integration of implants with increased surface roughness: a long term study in the sheep.

OBJECTIVES: This study evaluated the quality and the remodeling of bone around commercially pure titanium implants after 3, 6, 12 and 18 month implantation periods in the sheep. METHODS: Twelve animals were implanted in the cortico-trabecular areas of both femurs. Each femur received four implants with a rough surface (type 1) in the right femur and four with a smooth surface (type 2) in the left one. Bone blocks containing the implants were studied by histomorphometry on undecalcified specimens. The amount of bone around implants was measured (bone volume, fractional woven bone volume, bone thickness, contact interface) together with osteoblastic activity (mineral apposition rates, bone formation rates) and resorption activity (eroded surfaces). RESULTS: No significant differences could be observed for the two types of implants between 3 and 6 months. At 12 and 18 months, bone volume and contact interface were still increasing and there was always a tendency for type 1 implants to be associated with higher values. On the contrary, mineral apposition rate, bone formation rates and eroded surfaces decreased in the referent area in contact with the implant; this phenomenon of 'return to the normal' was more evident with type 1 implants. The remodeling process appears to increase bone quality and bone-titanium interface around implants in long term periods. CONCLUSIONS: The net bone quantity necessary to immobilize implants is obtained rapidly but the adapting process to mechanical strength can lead to a small but persistent increase in bone volume around implants. Although the differences between type 1 and type 2 implants were often small or statistically insignificant, the rougher type 1 implants seemed to be associated with stronger bone response.

Adaptation, Physiological↗
PubMedDate not supplied

The early remodeling phases around titanium implants: a histomorphometric assessment of bone quality in a 3- and 6-month study in sheep.

The purpose of this study was to evaluate the quality of the bone matrix around commercially pure titanium implants at 3 and 6 months postplacement in sheep. Implants were placed in the corticotrabecular areas of both femurs in 6 animals. Each animal received 4 Euroteknika implants in the right femur and 4 Nobel Biocare implants in the left femur. Bone blocks containing the implants were studied undecalcified after being embedded in methylmethacrylate. Sections were stained with toluidine blue and basic fuchsin. The amount of bone around the implants, the contact interface between the implant and bone, and the mineral apposition rates were measured. The fractional amount of woven bone could be quantified because of its high glycosaminoglycan content. No differences could be observed between the 2 types of implants. Total bone volume did not increase around both types of implants between 3 and 6 months, indicating that ankylosis was rapidly achieved. In contrast, in the area in contact with the implant, the bone-titanium interface drastically increased and the mineral apposition rate decreased. The fractional volume of woven bone around implants was considerably reduced after 6 months. Bone quality around implants was improved at 6 months (volume of woven bone near zero), and true osteonic structures were observed in close contact with titanium. The remodeling process appeared to improve bone quality and increase the bone-titanium interface around implants, while the net bone quantity necessary to immobilize implants was achieved rapidly and remained unchanged.

Animals↗
PubMedDate not supplied

[A rare cause of hypercalcaemia: familial hypocalciuric hypercalcaemia (author's transl)].

Two cases of familial hypocalciuric hypercalcaemia (FHH) in the same family are presented. This congenital disease is characterized by biochemical evidence of parathyroid toxicity but differs from primary hyperparathyroidism by the presence of normal parathyroid hormone levels. However, histomorphometric studies of transiliac bone biopsy specimens after double-labeling with tetracycline shows intensive remodelling of bone tissue with increase in osteoclastic resorption and osteoblastic apposition areas, all features identical with those observed primary hyperparathyroidism. The authors suggest hypersensitivity of target-organs (bones and kidneys) to parathyroid hormone as a probable physiopathological mechanism for FHH.

Adult↗
PubMedDate not supplied

Does titanium surface treatment influence the bone-implant interface? SEM and histomorphometry in a 6-month sheep study.

Two types of threaded titanium implants (Euroteknika and Nobel Biocare) were compared in a 180-day in vivo experiment in sheep. The implant characteristics were analyzed by scanning electron microscopy and image analysis to determine the roughness index of the surface. Implant specificity appeared through their slightly different chemical composition, their peculiar thread morphology, and their different roughness indexes (0.214 and 0.139, respectively). Implants were placed in the distal part of the tibial diaphysis. Histomorphometric analysis of the bone-implant interface was done on bone sections processed undecalcified. Both types of implants exhibited a similar bony reaction, with haversian bone in close contact with the titanium surface without interposition of fibrous tissue. The interface length percentage covered by bone was not significantly different between the two types of implants.

Animals↗