PubMed Health⌕ Search

Biomedical subjects

F C Chrétien

Publications and source records attributed to F C Chrétien.

At least 19 recordsLinked to original sources
PubMed2003

[Degradation of copper IUDs in utero. The process of metallic corrosion. A scanning electron microscope study].

OBJECTIVE: The present investigation was carried out in order to study the process of metallic corrosion of copper IUD's in utero, to precise its dynamics and location along the IUD and to appraise the influence of eventual calcareous deposition. MATERIAL AND METHODS: A total of 461 copper IUDs representing four standard models were screened by means of optical microscopy. Especially typical samples were studied at higher magnifications under the scanning electron microscope. The obtained data were considered in terms of statistics. RESULTS: It was possible to demonstrate a preferential corrosive activity in the lower part of the IUD without significant variations between the models. It was also possible to precise the steps of the process, to describe its most characteristic aspects and to study the eventual effect of severe calcareous deposition on corroded copper. DISCUSSION AND CONCLUSIONS: Intrauterine copper corrosion is a normal process which occurs preferentially in the cervical portion of an IUD and can lead to the total metal loss. Both its initiation and evolution are submitted to strong individual variations. Thick and compact vaterite deposits may thwart copper erosion in case of drastic and rapid deposition.

Copper↗
PubMed2002

[I.U.D. degradation in utero as a function of time: the phenomena of calcification. Radiocrystallographic and scanning electron microscopy study].

OBJECTIVE: A study was undertaken in order to determine the frequency of the process of calcareous deposition, to clarify the nature of the deposits, their arrangement along the IUD and their possible influence on the appearance of metrorrhagias. MATERIAL AND METHODS: A total of 408 coopper IUD's belonging to four standard models were observed by means of optical microscopy at low magnifications. The most typical samples were studied under the scanning electron microscope and deposits analyzed by crystallography. The data were analysed statistically. RESULTS: It was possible to determine both the frequency and the importance of the process of calcification according to the model of IUD and to the bearing time, to demonstrate a preferential location of concretions and to suspect a sensibility to the phenomenon variable according to the model. It was also possible to clarify the stages of the process of calcification, to describe its most characteristic aspects and to identify the essential component of calcareous deposits. CONCLUSIONS: Calcification concerns roughly over 50% of IUD's in utero. It occurs preferentially on the fundic portion of an IUD. Obviously, the minimal time required for the phenomenon to start as well as to increase its intensity are submitted to strong individual variations. Concretions are composed of vaterite, a distinct variety of carbonate of calcium. They do not seem to be the primary cause of possible metrorrhagias.

Calcium↗
PubMed1998

[Atomic absorption spectrophotometry study of copper ion release by copper-bearing intrauterine devices].

Copper release from copper-bearing IUD's was studied in vitro and in vivo using atomic absorption spectrophotometry in deionized water, normal saline solution and normal ovulatory cervical mucus. In these media, copper release from a 375 mm2 DIU occurs without latency, showing comparable amounts for identical time intervals. Daily copper release was shown to be respectively 8 and 11 times higher in cervical mucus and normal saline solution than in deionized water. Although copper ions are detectable in ovulatory cervical mucus under physiological conditions, the copper content appears 5 to 6 times higher in women bearing a copper IUD. Obviously, the copper amount is dependent on the copper exposed surface: the daily in vitro release from a 250 mm2 IUD is 18% inferior to that observed from a 375 mm2 model. In vivo, the daily copper release in ovulatory mucus of 380 or 200 mm2 IUD users is respectively 5 and 3.5 times higher than in controls.

Adult↗
PubMed1991

Anisotropic crystalline microstructures in dendritic arborizations of dried mid-cycle cervical mucus: surface morphology and crystallographic study.

Studies using scanning electron microscopic techniques permitted characterization of the nature and structure of the anisotropic elements present in dried preparations of mid-cycle cervical mucus. Sodium and potassium sulphates were located in the dehydrated matrix either isolated or bound to the dendrites. Depending on crystallization conditions, they appeared as well-formed individual crystals or as spherulites.

Adult↗
PubMed1989

A new crystallographic approach to fern-like microstructures in human ovulatory cervical mucus.

A new approach to fern-like structures in dried ovulatory cervical mucus has been carried out. Polarizing microscopy and conventional X-ray devices permitted these well-known structures to be demonstrated as being, both in nature and structure, more complex than previously described. The core of the dendrites appears to be mainly composed of NaCl, but also of KCl. They appear, under the polarizing microscope, as isotropic crystals. Anisotropic structures can be observed either at the periphery of the dendrites or isolated as small spheroliths. Anisotropic structures are insensitive to temperature variations but highly hygroscopic. They become rapidly amorphous when placed at room temperature without caution. The anisotropic period, 7 days long, is inscribed within the ferning period. Maximum anisotropy corresponds to the maximum production of cervical mucus, spinability value and basal body temperature rise. Anisotropic structures may be considered to be characteristic structures occurring spontaneously in ovulatory cervical mucus. These newly described structures consist of sodium or potassium sulphates.

Adult↗
PubMed1988

Improvement of human ovulatory cervical mucus by alpha-amylase. Effect on spinability and crystallization in vitro.

Alpha-amylase can modify ovulatory cervical mucus in vitro, changing both its structure and an essential rheological parameter, spinability. After 5 min at alpha-amylase concentrations above 4.6 mg/ml, spinability was greatly reduced or even non-existent because of the total liquefaction of the mucus. These concentration levels also induced breakdown of the solid phase of the hydrogel, producing more or less marked abnormalities in mucus crystallization after air drying. In the presence of the highest alpha-amylase concentrations (greater than or equal to 37.5 mg/ml) dendrites could not be formed and only sodium chloride crystals were visible at high magnification under a scanning electron microscope. In the 75 to 1.2 mg/ml concentration range, where alpha-amylase has a significant action on cervical mucus, there was an overall decrease in average spinability as the enzyme concentration fell. The action of the enzyme was greater after 10 min than after 5 min reaction time. For the 10-min reaction time interval, the activity could be adjusted using a squared polynominal regression, whereas for the 5-min reaction time interval a linear regression was a suitable model of enzymatic activity. In the 4.6 to 1.2-mg/ml concentration range, adjustment on a linear model showed that there was a significant effect of alpha-amylase concentration and reaction time on mucus spinability. Statistical analysis of the dose-effect data was compatible with the structural changes in dried cervical mucus demonstrated by scanning electron microscopy.

Adult↗
PubMed1980

The evolution of cervical mucus infrastructure in normal cyclic baboons (Papio anubis) and castrated females receiving hormonal supplies. A scanning electron microscope study.

The scanning electron microscope was used to study the evolution of the infrastructure of cervical mucus in normal cyclic baboons and in castrated animals treated with ovarian hormones for establishing an artificial cycle. In both groups, the results make conspicuous the progressive enlargement of the filamentous woof, which attains a maximum at midcycle and then decreases by degrees in the second part of the cycle. It was shown that the evolution of the framework is very similar during normal and artificial cycle, with only variations of slight amplitude. Moreover, the variations in the baboon mucus infrastructure closely resemble those described in the human. The results are briefly discussed in the light of known data.

Animals↗
PubMed1979

Cellular thorn-like projections in human endocervical epithelium. Preliminary scanning electron-microscopic study.

By means of scanning electron-microscopic investigations, thorn-like projections (TLP) were observed in the cilio-secretory epithelium of the ventral surface of the human endocervix. These projections, which seem to be characteristic of a new cell type, were seen at different stages of the menstrual cycle (days 8, 14 and 21) in 4 apparently healthy fertile women. Striking differences in length, with a maximum size at midcycle, suggest an evolutive process throughout the menstrual cycle. The origin and possible physiological role of TLP in the reproductive process are discussed.

Adult↗
PubMed1978

Ultrastructure and variations of human cervical mucus during pregnancy and the menopause.

Ultrastructural aspect and variations of cervical mucus have been studied by scanning electron microscopy in 58 pregnant and 29 menopausal women. In both groups, a striking tightening of the ultrastructural glycoprotein framework was demonstrated. The phenomenon appears to occur very rapidly at the beginning of pregnancy while patients near the menopause show more variable patterns. The results are compared to the known evolution of cervical mucus ultrastructure during the ovarian cycle and discussed from a rheological point of view. Particular attention was paid to the eventual antibacterial role of cervical mucus in pregnancy, which was found to be very plausible.

Adult↗
PubMed1977

[Cervical mucus. III. Physiological roles].

The first part of this large review on the bibliography of cervical mucus was concerned both with the mechanism and the determinism ensuring its secretion. A second paper reviewed the present knowledge on chemical, physical ultrastructural characteristics of cervical mucus. This paper, the last part of the review, will be concerned with the different functions of the mucus ensuring synchronisation and encounter of the germ cells. From a physiological point of view, the following properties may be ascribed to the cervical secretion: - protection of sperm from the hostile environment of the vagina, and from being phagocytized along the cervical canal ; - cyclic receptivity to sperm penetration at or near ovulation and interference with entry at other periods ; - filtering effect on sperm cells; - possible intracervical sperm storage ; - supplementing the energy requirements of sperm ; - protection of the uterine cavity against bacteria.

Animals↗
PubMed1977

Scanning electron microscopy of ejaculated baboon (Papio anubis) spermatozoon.

Scanning electron microscopy has been used in order to provide the morphological study including comparative measurements of the main parts of the Baboon spermatozoon. If the dimensions of the head and the mid-piece are fairly close to the human spermatozoon, the Baboon spermatozoon is practically twice as long as the human one. In the Baboon spermatozoon, the head appears smooth with only a light ransversal furrow at the level of its posterior third, which probably marks the limit of the posterior border of the equatorial segment. The mid-piece, a conical trunk, is larger in its anterior part than at the level of its posterior extremity. The end-piece appears very short as compared with the total length of the sperm cell. The technical modalities of the preparation and the possibility of artifacts are briefly discussed.

Animals↗