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C Chevalier

Publications and source records attributed to C Chevalier.

At least 19 recordsLinked to original sources
PubMed1992

Screening for Y-derived sex determining gene SRY in 40 patients with Turner syndrome.

In Turner patients, the presence of a Y chromosome or derivative Y is correlated with the risk of gonadoblastoma induction. "Marker" chromosomes originating from Y, may not show characteristic fluorescence and then be very difficult to identify by conventional cytogenetic techniques, although they still predispose the patients to gonadal tumors. Using polymerase chain reaction of the gene from the sex-determining region of the Y chromosome, we screened 40 Turner patients (thirty seven 45X and three 45X,46XX) for the presence of Y chromosomal DNA. We were able to identify karyotypically unrecognized Y chromosome material in 1 patient out of the 40 studied. In this patient mild clinical and biological hyperandrogenism was observed. Reliability of our technique was ascertained by the detection of the expected 648 base pairs amplified DNA fragment in all normal male controls as well as in 3 Turner patients with confirmed 45X,46XY mosaicism. Despite the low frequency of unrecognized Y chromosome material (1 case over 40 in our experience), our data suggest that polymerase chain reaction of the gene from the sex-determining region of the Y chromosome is worthy of being performed in Turner patients considering the potential risk of the presence of a Y chromosome.

Adolescent↗
PubMed1992

[Calculation of optimized and individualized hip prosthesis. A study of feasibility].

As logical consequence of a series of basic research studies on human femoral bones with unipodal support and under static stress, performed with physicomathematic modelling methods (finite-elements method) then confirmed by direct visualization of deformations resulting from such stress using holographic interferometry, the authors have worked on the definition of an optimized and individualized hip prosthesis. Thick CT sections digitized with a table and entered into a specially programmed computer allowed three-dimensional modelling of the femur as a volume, i.e. with its external contour and its medullary canal, and therefore of the implantable space. The prosthesis was then defined taking a number of hypotheses into account: necessity to regularize cortical bone spicules inside spongious bone, which are so often present opposite the rough line, partial machining at the level of the calcar, reduced tail length, presence or absence of collar. Thus an optimized and individualized prosthesis was defined. A prototype corresponding to a given femoral bone could then have been produced. However, the authors found it preferable to use simulation with computer synthetic images to check easy insertion and removal.

Acetabulum↗
PubMed1991

Management of hyperandrogenism in adolescent girls.

Hyperandrogenism in adolescent girls can be a troubling problem because of the difficulty in establishing a diagnosis and in prescribing appropriate therapy. Androgen excess in adolescent patients encompasses a spectrum of clinical presentations, including acne, hirsutism, oligomenorrhea, amenorrhea, virilism, and ovarian cysts. Androgen excess is a clinical and chemical feature of idiopathic hirsutism, late-onset forms of congenital adrenal hyperplasia, and polycystic ovarian disease; in some cases, functional hyperandrogenism is discussed. We recommend screening for hyperandrogenism by measuring blood levels of testosterone, dehydroepiandrosterone sulfate, and delta 4-androstenedione, while others propose a first dexamethasone suppression test for evaluation of free testosterone, dehydroepiandrosterone sulfate, and cortisol. Treatment will be chosen according to particular symptoms such as acne, hirsutism, obesity, or oligomenorrhea.

Acne Vulgaris↗
PubMed1990

[Estimation of the number of kidney recipients with a functional graft in France, from 1975 to 1994].

The evolution observed in the number of kidney grafts performed in France and the number of recipients living with a functional graft is described. Using the data collected between 1975 and 1988 and the graft survival rates, the size of this population for the 5 forthcoming years can be predicted. The annual number of kidney grafts will stabilize at 2,750 in 1993, if we assume a limit of 50 grafts per million inhabitants, which is the maximum rate currently observed in several regions of France. At this level, the organs used for kidney retransplantations would begin to reduce the availability of kidney first grafts. These predictions are based on the assumption that no major adverse change will occur in the current organ procurement policy. The total number of kidney recipients would then reach about 17,700 in 1994. This population has increased fivefold since 1980 and will double in the forthcoming years. Henceforth, plans for financial and human resources to ensure the follow-up of this population should be implemented.

Adolescent↗
PubMed1990

Retroperitoneal fibrosis in two patients with Parkinson's disease treated with bromocriptine.

Retroperitoneal fibrosis has been observed in two patients with Parkinson's disease treated with bromocriptine. The patients complained of abdominal or lower back pain and presented with various degrees of renal insufficiency, with anuria in one. Laboratory evaluation furthermore showed an increased sedimentation rate and inflammatory anemia. Computerized tomography disclosed marked retroperitoneal thickening, and biopsy was performed in one patient. The symptoms appeared eighteen months and five years after treatment was started, at doses of 20 and 22.5 mg of bromocriptine daily. The medication was discontinued in both patients and steroid therapy was initiated, with resolution of all clinical, biological and radiological evidence of disease. This potential but rare complication of a widely prescribed drug warrants monitoring of renal function and sedimentation rate in patients undergoing bromocriptine treatment.

Aged↗
PubMed1990

Spiralins of Spiroplasma citri and Spiroplasma melliferum: amino acid sequences and putative organization in the cell membrane.

Spiralin is the major membrane protein of the helical mollicute Spiroplasma citri. A similar protein occurs in the membrane of Spiroplasma melliferum, an organism related to S. citri. The gene encoding spiralin has been sequenced. A restriction fragment of the spiralin gene has been used as a probe to detect the gene encoding S. melliferum spiralin. A 4.6-kilobase-pair ClaI DNA fragment from S. melliferum strongly hybridized with the probe. This fragment was inserted in pBR322 and cloned in Escherichia coli. It was further subcloned in the replicative forms of M13mp18 and M13mp19, and its nucleotide sequence was determined (GenBank accession number M33991). An open reading frame showing 88.6% base sequence homology with the S. citri spiralin gene could be identified and was assumed to be the gene encoding S. melliferum spiralin. The deduced amino acid sequence of the protein had 75% homology with the spiralin sequence. In particular, the two proteins possess a stretch of 20 amino acids which can form an alpha-helix, in which all polar amino acids occupy approximately one-third of the axial projection down the helix. On the basis of these data and published data, we propose a topological model for the structural organization of the spiralin in the cell membrane of spiroplasmas.

Amino Acid Sequence↗
PubMed1990

Organization and nucleotide sequences of the Spiroplasma citri genes for ribosomal protein S2, elongation factor Ts, spiralin, phosphofructokinase, pyruvate kinase, and an unidentified protein.

The gene for spiralin, the major membrane protein of the helical mollicute Spiroplasma citri, was cloned in Escherichia coli as a 5-kilobase-pair (kbp) DNA fragment. The complete nucleotide sequence of the 5.0-kbp spiroplasmal DNA fragment was determined (GenBank accession no. M31161). The spiralin gene was identified by the size and amino acid composition of its translational product. Besides the spiralin gene, the spiroplasmal DNA fragment was found to contain five additional open reading frames (ORFs). The translational products of four of these ORFs were identified by their amino acid sequence homologies with known proteins: ribosomal protein S2, elongation factor Ts, phosphofructokinase, and pyruvate kinase, respectively encoded by the genes rpsB, tsf, pfk, and pyk. The product of the fifth ORF remains to be identified and was named protein X (X gene). The order of the above genes was tsf--X--spiralin gene--pfk--pyk. These genes were transcribed in one direction, while the gene for ribosomal protein S2 (rpsB) was transcribed in the opposite direction.

Amino Acid Sequence↗
PubMed1990

The Mz variety of the St(a+) phenotype--a variant of glycophorin A exhibiting a deletion.

The NeuNAc level of erythrocyte membranes from two related donors exhibiting the Mz variety of St(a+) phenotype within the MNSs blood group system was found to be decreased by about 16%. The quantity of glycophorin A was decreased by about 38%, whereas that of glycophorin B was not significantly different from normal. Mz erythrocyte membranes were also found to contain an abnormal component (molar ratio to glycophorin A about 0.89:1.0) with an apparent molecular mass of about 24,000 Da. Immunoblotting experiments and amino-acid sequence analysis revealed that the novel component (and glycophorin A in one of the donors) carries blood group M activity. Blood group N activity was demonstrable for glycophorin A and glycophorin B from both donors. Amino-acid sequence analysis of chymotryptic, tryptic and cyanogen bromide peptides demonstrated that the novel molecule exhibits the typical structure of a Sta-active molecule. However, since it exhibits blood group M activity, it appears to represent a variant of glycophorin A lacking the residues 27-58 (encoded by exon three of the glycophorin A gene) rather than a glycophorin B-glycophorin A-hybrid molecule of the anti-Lepore type. Since one of the Mz heterozygotes was found to exhibit both M- and N activity on glycophorin A, the Mz gene complex appears to encode a blood group N-active glycophorin A apart from the novel component and a blood group s-active glycophorin B, although the level of glycophorin A in the erythrocyte membranes is decreased by about half.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1990

[Leiomyosarcoma of the scrotum].

Scrotal leiomyosarcoma is a rare tumor which may occur from each muscular structure of the scrotum. A brief review of the literature and the therapeutic possibilities are presented.

Aged↗
PubMed1990

[Cranial osteopathy, delusion or reality?].

After having outlined the theories of cranial osteopathy (SUTHERLAND, KARNI, UPLEDGER, and, more recently, CLAUZADE and DARRAILLANS), the authors refute the latter point by point. "Primary respiration" is in fact a way of thinking, and the various bones making up the calvaria and base of the skull, which are solidly synostosed in the adult, are clearly incapable of the pretended rhythmic displacements "described" by the osteopaths. Moreover, the C.R.L., like any liquid, is incompressible and mildly pulsatile. Conversely, although the brain clearly shows rhythmic pulsations, which every neuro-surgeon notes every day, the latter are exclusively connected to the vascular system.

Complementary Therapies↗
PubMed1990

[The biomechanics of the base of the skull and face].

The biomechanics-, engineering- and anatomy-oriented authors studied the craniofacial structures emphasizing their perfect adaptation to stresses developing during mastication or related to head statics and motions. For a better understanding of the biomechanics of the basis of the skull and face, attention is consistently drawn to solutions used in state-of-the-art engineering, such as aeronautics, in consideration that such solutions as are chosen by engineers are often--consciously or not--copied from nature.

Adaptation, Physiological↗
PubMed1989

Reflections on the mechanical structure of the base of the skull and on the face. Part 1: Classical theories, observed structures.

Using thick sections of the base of the skull and face their mechanical structure is viewed from the engineering aspect and the anatomic solutions evolved are compared with those selected by Aerospatiale engineers for the concept and development of the Airbus. It is concluded that the anterior and middle cranial fossae, together with the face, constitute an inseparable mechanical assembly each of whose component units participate in the rigidity of the others. Since this mechanical assembly must provide maximal rigidity for minimal weight, this suggests that aeronautical solutions should throw much light on the detail of construction of the skull and face. Indeed, the rigidity and lightness of the latter are obtained by means of solutions familiar in aeronautics: the reliance on thin-shelled beams with a honeycomb filling, the diploe analogous to a preconstrained composite or sandwich structure, a system of frames, struts and stiffeners, and the use of fillets at the sites of junction of struts.

Biomechanical Phenomena↗
PubMed1989

A retrospective and prospective study of the number of kidney transplants in 31 countries.

The aim of the present study was to try to predict the number of cadaveric kidney transplantations (CKT) that will be performed in the year 1993. The raw data regarding the number of renal transplants that have been performed annually since 1975 in 31 countries, which were divided into six groups, were collected from published reports and confirmed by a questionnaire sent to all centers. The annual number of grafts was estimated using an exponential model, highly correlated with retrospective data (r2 greater than 0.99). Predictions for 1993 were extrapolated. The growth of transplantation activity is limited by a shortage of available donor organs. The maximum number of grafts was arbitrarily set at 40 per million population, which is the maximum rate currently observed. The total number of CKT carried out between 1975 and 1986 was 114,000; this will probably exceed 280,000 in 1993. The yearly activity in 1987 exceeded 16,500 and is expected to reach approximatively 26,000 grafts in 1993.

Africa, Northern↗
PubMed1988

Biomechanics of the calvarium.

The authors question whether strengthening beams and spans for the calvarium really exist and, if so, what are their exact anatomic counterparts and their exact function in the resistance of the calvarium. They opine that this function is of secondary importance except for the frontal and internal occipital pillars. The resistance of the calvarium must rather be attributed to its sandwich structure, with local bracing where the constraints are too severe. While they believe in the existence of such braces as the occipital pillars between the calvarium and the endochondral skull base, they prefer the concept of the mastoid pillars. The mastoid process is a structure with a thin shell and alveolar content, which has the advantage of giving the sternocleidomastoid and digastric muscles a bigger area of attachment to a light structure.

Biomechanical Phenomena↗