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Biomedical subjects

P Lecomte

Publications and source records attributed to P Lecomte.

At least 73 records · Page 4Linked to original sources
PubMed1990

Diagnosis of medullary carcinoma of the thyroid (MCT) by calcitonin assay using monoclonal antibodies: criteria for the pentagastrin stimulation test in hereditary MCT.

A new calcitonin (CT) immunoradiometric assay, using anti-11-7 and anti-24-32 CT fragment monoclonal antibodies was evaluated and compared to classical RIA. The sensitivity was 2.5 ng/L, the normal basal level (n = 83) was lower than 10 ng/L, the response to pentagastrin stimulation in control subjects was absent in nine and between 10-30 ng/L in nine others. (mean, 15.4). In patients with renal failure the basal level was increased between 10-52 ng/L. In patients with medullary thyroid carcinoma (MTC; n = 28), the basal level was between 189-28,900 ng/L. A pentagastrin test was performed as screening for familial MTC in eight patients with confirmed MTC at subsequent surgery; the calcitonin peak was equal or greater than 38 ng/L. Large differences exist between CT levels measured by RIA and immunoradiometric assay. The latter method provides a greater sensitivity to pentagastrin test and allows a better identification of microcarcinoma in hereditary cases of MTC.

Adolescent↗
PubMed1990

[Steroid-sensitive cavitating pulmonary opacity in Horton's disease].

We report the case of a 72 year old woman treated for seven months for Horton's disease presenting with a cavitating pneumonia of the left axillary segment associated with a deterioration of the general state, at the time of which the steroid therapy was in the course of being decreased. The radiological appearance and the clinical context of immune depression had led to a trial of a quadruple anti-tuberculous therapy in spite of the absence of any bacteriological proof. This rapid aggravation of the condition under treatment led to the suggestion of a pulmonary localisation of Horton's disease. The rapid regression of the lesions after increasing the dose of steroids and the negative cultures on Lowenstein medium pleaded in favour of this hypothesis. However the continuation of anti-tuberculous treatment seems justified in such cases in so far as the diagnosis of Horton's disease of the lung often cannot be maintained other than retrospectively in the absence of histological proof.

Aged↗
PubMed1989

Evidence of 11 beta-hydroxylase deficiency in a patient with cortical adrenal adenoma.

We explored a 61 year old woman with mild hirsutism. An adrenal tumor was found in the left adrenal, which was held responsible for the androgen secretion. The in vitro incubation of the tumor tissue showed an impaired 11 beta-hydroxylation of 11-deoxycortisol. This is a rare and unusual case of adrenal pathology showing that a deficiency in 11 beta-hydroxylase activity does not rule out the presence of an adrenocortical adenoma.

Adenoma↗
PubMed1989

Ectopic prolactinoma within the sphenoid sinus.

A case of an ectopic prolactin-producing tumor located within the sphenoid sinus is reported. It was discovered in a girl who experienced secondary amenorrhea without galactorrhea. We discuss the different diagnoses proposed before immunocytochemical staining results were available. This case presented unusual radiological, surgical, and histopathological aspects.

Adolescent↗
PubMed1988

[Thyroid ectopia and Basedow's disease].

Graves' disease was diagnosed in a 35-year old woman with a history of myxoedema in childhood. Clinical data, ultrasonography and radioisotope scanning showed that the disease had developed in an ectopic subhyoid thyroid gland. Although numerous thyroid diseases associated with an ectopic thyroid have been described, Graves' disease does not seem to be frequent since only one case has been published so far.

Adult↗
PubMed1988

Seminal fluid transferrin as an index of gonadal function in men.

Seminal fluid transferrin concentrations of proven fertile donors and normozoospermic patients were significantly higher (P less than 0.001) than those in other groups examined. There were no significant differences in the transferrin values among vasectomized, azoospermic and very severe oligozoospermic subjects. Values were also similar in patients affected by secretory or excretory azoospermia. Regression analysis showed a positive correlation (P less than 0.001, r = 0.72) between seminal fluid transferrin concentrations and sperm density. A negative correlation (P less than 0.02, r = 0.28) existed between circulating FSH and seminal fluid transferrin concentrations. There were no significant differences between seminal fluid transferrin and the percentages of abnormal sperm cells or immature seminal line elements. These results indicate that the nature of seminiferous tubule dysfunction can be precisely defined by examining seminal fluid transferrin in combination with other biological values usually used to explore testicular function.

Follicle Stimulating Hormone↗
PubMed1988

[Experimental Enterobacter cloacae endocarditis treated with gentamicin. Predictive value of the in vitro bactericidal rate].

The predictive value of in vitro time-kill curve was tested on an Enterobacter cloacae endocarditis experimental model. The antibiotic studied was gentamicin. Despite a similar MIC, 2 Enterobacter cloacae strains exhibited very different time-kill curves in vitro. This difference was found being predictive of efficacy on the in vivo model, 24 hours after a single injection of gentamicin.

Animals↗
PubMed1988

[An in vitro study, in the human, of the relation between epididymal spermatozoa and the zona pellucida].

The ability of non capacitated human spermatozoa recovered from the caput, corpus and cauda epididymis, to bind the isologous or heterologous (rat) zona pellucida has been investigated. Experiments were performed with cold immobilized spermatozoa to avoid differences resulting from motility into the epididymis. Comparison with similar investigations in the ram (works and review of Fournier-Delpech and Courot, 1987) lead to conclude that human spermatozoa are: 1) able to bind to the human zona in the proximal epididymis; 2) unable to recognize heterologous zona at any level of the epididymis. From this, a strict species-specificity of the sperm-zona interactions exists in the proximal epididymis, in the human. By contrast, in the ram, sperm-zona binding develops in the epididymis iso- or hetero-specifically. Restricted species specificity appears in the ejaculate only. Data are in agreement with species specificity of gametes interactions in the human (Bedford, 1977). Such results could contribute to explain in vitro or in vivo fertilization with sperm originating from the middle epididymis (Temple-Smith et al., 1985; Soychsman and Bedford, 1986).

Adolescent↗
PubMed1988

[Insulin-resistant diabetes and polycystic ovary].

The observation of one patient with insulin resistance (114 unités of soluble insulin in 3 injections per day + 54 units of medium acting insulin at 8 pm) associated with a polycystic ovarian disease prompted us to discuss the relationship between hyperandrogenism, acanthosis nigricans and endogenous hyperinsulinism. An in vitro study of the insulin binding to patient's erythrocytes allowed to diagnose the rare Type A insulin-resistance syndrome proposed by Kahn.

Adolescent↗
PubMed1987

A method for measuring testosterone-estradiol-binding globulin--new analysis of experimental data and comparison with two commercially available kits.

Some binding assays have been suggested to measure serum testosterone--estradiol-binding globulin (TeBG) concentration. They have led to discrepant results. This study brought to surface the lack of these methods and the interest of a method using an accurate analysis of the binding isotherm. These observations led us to propose an absolute reference method especially suitable for the radioimmunological assays standardization. Our method used Con A Sepharose as a solid phase and DHT as a radioligand. We succeeded in solving the difficulties related to binding methods by evaluating the non-specific binding of the ligand and ligand--albumin binding. A careful analysis of experimental data, by setting equations specific to this DHT-TeBG system permitted the systematic errors to be corrected and allowed a precise determination of the serum TeBG concentration (27.3 +/- 6.0 nmol/l for 30 healthy men; 40 +/- 13 nmol/l for 15 healthy women). Moreover, the affinity constant of the ligand for the protein was accurately evaluated KDHT = (0.7 +/- 0.1)10(9) (mol/l-1) at 20 degrees C, which was not permitted by other methods. Two lines of evidence supported our assumptions and results. On the one hand, using estradiol as a radioligand instead of dihydrotestosterone, we found the same value for serum TeBG concentration; on the other hand, our assay favourably compared with two different kits commercially available. The correlation (r = 0.89) with 3H-SBP kit Merieux was good though this kit was not suitable for correctly assaying serum TeBG concentrations between 30 nmol/l and 60 nmol/l. An excellent correlation (r = 0.97) with SHBG IRMA Kit Farmos was found. This antibody-based assay and our binding assay yielded quite similar values that mutually validated both methods.

Binding, Competitive↗
PubMed1987

The influence of salivary flow rate on diffusion of potassium chloride from artificial plaque at different sites in the mouth.

The rate at which substances diffuse from dental plaque influences the rate of clearance of acid and bacterial toxins from plaque into saliva. The aim of this study was to compare the rates of clearance of potassium chloride, as a model substance, from artificial plaque of 3-, 4-, and 6-mm-diameter, positioned bilaterally at different locations in the mouth. The diffusant was KCl (1 mol/L) in a 1.0% agarose matrix, placed in wells 1.5 mm deep, in small acrylic devices 3 mm thick, which could be fastened to the teeth with dental floss and removed after different time periods. The half-time for clearance was determined from the best-fitting least-squares line of the potassium concentration remaining in the gel plotted against the square root of time. For 14 subjects, half-times for the lower anterior lingual and upper posterior lingual regions averaged about 2.5 times greater than those for clearance into a large, stirred volume in vitro, whereas those for the upper and lower anterior buccal regions averaged about 12.8 times greater. This difference may be due to the fact that anterior buccal sites are exposed only to minor rather than to major salivary gland secretions. When salivary flow was stimulated by the sucking of sour lemon drops, all in vivo half-times were reduced by about one-half. The half-times were also directly related to the surface areas of the chambers, which implies that rates of diffusion from plaque of substances such as acid or bacterial toxins are inversely related to the surface area of the plaque at a particular site.

Acrylic Resins↗
PubMed1986

Evidence for an intermediate in DNA synthesis involving pyrophosphate exchange. A possible role in fidelity.

The incorporation of exogenous deoxyribonucleotide monophates (dNMP) was measured under conditions of ongoing DNA synthesis, providing arguments for the existence of a [DNAn X dNMP X PPi] intermediate in the nucleotide incorporation step of DNA synthesis: (formula; see text). The existence of such an intermediate is suggested by an apparent exchange of both dNMP and pyrophosphate (PPi) moieties of the deoxyribonucleotide triphosphate (dNTP) substrate with exogenous molecules. Such exchange and the incorporation of exogenous dNMP into DNA, strictly require ongoing DNA synthesis, suggesting that the energy for exchange reactions is provided by the cleavage of dNTP substrate. We propose that nucleotide selection during ongoing DNA synthesis results largely from the different relative rates of forward (beta) and backward (-alpha) reactions involving the [DNAn X dNMP X PPi] intermediate: the forward (incorporation) reaction is expected to predominate for the correct nucleotide, whereas the backward (abortive) reaction is expected to predominate for incorrect nucleotides.

Animals↗
PubMed1986

Mnemonic aspects of Escherichia coli DNA polymerase I. Interaction with one template influences the next interaction with another template.

When Escherichia coli DNA polymerase I (Pol I) replicates a homopolymer, the excision/polymerization (exo/pol) ratio varies with enzyme and initiator concentration. The study of this effect in the case of poly(dA).oligo(dT) replication led us to propose a mnemonic model for Pol I, in which the 3' to 5' excision activity warms up when the enzyme is actively polymerizing, and cools down when it dissociates from the template. The model predicts that the exo/pol ratio must increase with processivity length and initiator concentration and decrease with enzyme concentration. It predicts also that contact of the enzyme with one template alters its excision efficiency towards another template. The exo/pol ratio and processivities of Pol I and its Klenow fragment were studied on four templates: poly(dA).(dT)10, poly(dT).(dA)10, poly(dC).(dG)10 and poly(dI).(dC)10. We show that the Klenow fragment is usually much less processive than Pol I and when this is the case it has a much lower exo/pol ratio. At equal processivity, the exo/pol ratios are nearly equal. Furthermore, many factors that influence processivity length (e.g. manganese versus magnesium, inorganic pyrophosphate, ionic strength) influence the exo/pol ratio in the same direction. The study of deaminated poly(dC) replication, where we followed incorporation and excision of both G and A residues, allowed us to assign the origin of the dNMP variations to changes in the 3' to 5' proof-reading activity of Pol I. Similarly, the lower dNMP turnover of the Klenow fragment observed with deaminated poly(dC) was specifically assigned to a decreased 3' to 5' exonuclease activity. The exo/pol ratio generally increased with initiator and decreased with enzyme concentration, in agreement with the model, except for poly(dI).oligo(dC), where it decreased with initiator concentration. However, by terminating chain elongation with dideoxy CTP, we showed directly that, even in this system, excision is relatively inefficient at the beginning of synthesis. Interaction of Pol I with poly(dA).(dT) or with poly(dC).(dG) modifies its exo/pol characteristics in the replication of poly(dI).(dC) and poly(dA).(dT), respectively. The Klenow enzyme is not sensitive to such influences and this correlates with its reduced processivity on the influencing templates. Our results reveal the existence of differences between Pol I and its Klenow fragment that are more profound than has been thought previously.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Composition↗
PubMed1986

[Use of the mixed antiglobulin reaction (MAR) latex test in routine detection of antisperm agglutinating antibodies in subjects with spontaneous autoagglutination].

A mixed antiglobulin reaction: M.A.R. latex test has been used to detect the presence of either IgG or IgA on the surface of spermatozoa in a selected population with spontaneous agglutination. Positive M.A.R. tests showed a highly significant correlation with the presence of antisperm antibodies in seminal plasma or serum and with sperm penetration in cervical mucus. Autoantibodies against spermatozoa were found in 4.25% of seminal fluid samples.

Autoantibodies↗
PubMed1984

[Sympathetic paraganglioma. Scintigraphic detection using a new labeled molecule, meta-iodobenzylguanidine].

Two cases of sympathetic paraganglioma are reported: one, benign, in a 20-years old woman with arterial hypertension and attacks of excessive sweating; the other, malignant and with bone metastases, in a 44-years old woman. Both were diagnosed by scintigraphy, using meta-iodobenzylguanidine as radionuclide. This new radiopharmaceutic agent has recently been introduced for the detection of phaeochromocytomas, but it seems to be a general tissue marker of catecholamine uptake and storage. Its use as a therapeutic compound may also be envisaged.

3-Iodobenzylguanidine↗