PubMed Health⌕ Search

Biomedical subjects

M Mercier

Publications and source records attributed to M Mercier.

At least 73 records · Page 4Linked to original sources
PubMed1992

[Epidemiology of kidney cancers].

Renal carcinomas represent 2% of all tumors. More than 90% of these cancers occur in adults with the frequency in adult males being twice as high as that in adult females. The frequency of renal carcinomas is relatively high in France especially in males. Renal carcinomas mortality has been increasing in France over the last 40 years by more than 2% per year and suggests that tobacco is involved in this increase. Obesity, especially in women, and chronic renal failure are two other frequent associations found with renal carcinomas. The prognosis for this cancer is not clear-cut as the relative 5-year survival rate for all adult tumors ranges from 36 to 54%.

Adolescent↗
PubMed1992

[Langerhans-cell histiocytosis of the vulva. General review and a case history].

Localisation of Langerhans' cell histiocytosis (HCL) is rare. In solitary form the prognosis for this pathology is good, if the tumour occurs in a woman of 36 years of age. (In this case the woman's age was 91) The appearances may be misleading clinically. The diagnosis is made by histological examination of P-S 100 positive cells and by finding Birbeck's granules on electron microscopy. Treatment may be surgical or as in our case medical.

Administration, Topical↗
PubMed1992

[Comparison of morbidity and therapeutic load in premature twins and single births].

A prospective study was performed in order to compare birth weights, gestational ages at birth, perinatal and neonatal morbidity and mortality rates and therapeutic burdens given to 157 premature twins and 389 premature singletons. This study did not show real differences between premature twins and singletons, as if multiple pregnancies do not lead to other significant pathology than prematurity. The only observed differences were higher rates of breech presentation, wet lung disease, and lower rates of materno-foetal infection and pulmonary hypertension syndrome for premature twins.

Age Factors↗
PubMed1991

Stimulant effect of the beta-carboline FG 7142 in the open-field test.

The anxiogenic activity of N-methyl-beta-carboline-3-carboxamide (FG 7142) is sometimes difficult to observe in rats. As the open field has recently been applied successfully to test the anxiogenic potential of n-butyl-beta-carboline-3-carboxylate (beta-CCB) in mice, a comparable experiment was performed with FG 7142 (1, 5, 10, 30 mg/kg i.p.) in rats. In contrast to the inhibitory effects measured with beta-CCB, FG 7142 significantly increased the ambulation and rearing scores and induced aggressivity in some animals. A differential sensitivity of mice and rats to beta-carbolines, predominant analeptic properties of FG 7142, and differences in the types of anxiety induced are proposed to account for this discrepancy.

Animals↗
PubMed1991

International approach to the assessment of chemical risks.

One of the main objectives of the International Programme on Chemical Safety, a joint venture of the World Health Organization, the United Nations Environment Programme and the International Labour Organization, is to carry out and disseminate evaluations of the risk to human health and the environment from exposure to chemicals, mixtures of chemicals, or combinations of chemicals and physical and biological agents. These evaluations, performed by groups of internationally reputed and independent experts, provide a scientific and objective basis that national authorities may be able to use for planning and for the development of control measures, such as the establishment of exposure limits for chemical pollutants.

Environmental Pollution↗
PubMed1991

Effect of chronic hypoxic treatment on the retention of fixed-interval responding.

The present experiments aimed to study the effects of hypoxic treatment (10 min on 3.5% oxygen) on the stabilized performance of rats in a fixed-interval schedule (FI 60 s). The hypoxic treatment was given once a day, for 3 days, immediately after the FI session. The results showed that the operant performance was disturbed from the very first posthypoxia FI session. There was a sharp drop in response rate, and changes in the temporal distribution of responses occurred. The data obtained greatly limit the importance of nonspecific factors in explaining these changes in performance. The results are discussed with reference to the retrieval hypothesis. In particular, it is suggested that the decreases of performance may be due to an effect of hypoxia on the retrieval mechanisms associated with long-term memory.

Animals↗
PubMed1991

Effects of specific dopaminergic agonists and antagonists in the open-field test.

It has been found that dopaminergic transmission could be involved in some aspects of anxiety. The present study aims to explore this hypothesis further, using specific DA1 (SKF 38393) and DA2 (bromocriptine) agonists or DA1 (SCH 23390), and DA2 (zetidoline) antagonists in the open-field test. The results confirm previous studies indicating that DA1 and DA2 agonists predominantly increase locomotor activity, while DA1 and DA2 antagonists predominantly decrease it. However, at low doses, the four drugs increase the peripheral ambulation score significantly and, with the exception of zetidoline, also increase the central ambulation score. The observations made with zetidoline confirm the hypothesis that a specific presynaptic DA2 antagonism could be determinant for the disinhibitory effects of low doses of neuroleptics. A collateral action on 5HT transmission is also suggested to explain an hypothetic anxiolytic action of DA agonists and SCH 23390 at lower doses.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1991

Enhanced resistance effect of piracetam upon hypoxia-induced impaired retention of fixed-interval responding in rats.

Rats were trained on a fixed-interval schedule of 60 s (FI 60). After stabilization of performance, rats were chronically submitted to hypoxic treatment (3.5% O2, 10 min) once a day, immediately after the daily FI 60 session. Hypoxia disturbed the retention of FI responding. It was mainly characterized by a decrease in response rate and in pause duration, and by changes in the temporal distribution of responses. Animals receiving piracetam (100 mg/kg, IP) 30 min before each FI session followed by hypoxia were significantly less affected than saline-treated animals. Results are discussed with reference to the effects of hypoxia and piracetam on nonspecific factors and on memory function. It is suggested that the effects of piracetam are due to alleviation of hypoxia-induced memory retrieval deficit rather than to a protection against hypoxic brain cell injury.

Animals↗
PubMed1991

Evaluation from population registry data of health care expenditure during the 6 months after cancer diagnosis.

It is currently estimated in France, that the cost of cancer has risen to $3.8 billion, with an annual growth of 5-10%. This represents approximately 6% of all health expenditure. The data from the Registry of Tumors in the Doubs region have enabled us to make an evaluation of health expenditure, reimbursed by the French Securite Sociale (S.S.), and its distribution in relation to different activities (diagnosis, type of treatment, follow-up, transport), according to cancer site. In 1984, the average cost per patient within the first 6 months of the illness was evaluated at $4,000. The results show major differences for the cancer sites, care facilities and budget items. Diagnosis assessment represents 27% of all expenditure, surgery 37%, radiotherapy, chemotherapy and transport, 11% each. All kinds of expenses are fully reimbursed by the French S.S. and transportation, which at the beginning used to avoid hospitalization, is now used as a comfort system and represents a high cost to the S.S. The different costs for the same illness between private, general public and university hospitals do not reflect a difference in care, but rather different systems of calculating and functioning. Till now there has not been any logical evaluation of care in the French health system.

Data Collection↗
PubMed1991

Transforming signals into quantitative values and mathematical treatment of data.

The purpose of this article is to review some mathematical models which are available to calibrate immunoassays and interpolate analyte concentration. Several curve fitting methods are available, but few of them are currently used. Point-to-point linear interpolation is prone to bias when the rate of curvature of the calibration curve or when the random error are high. Polygonal interpolation connects each neighboring pair of data points with multiple connected line segments. Neither smooths the data. Smoothing models are often preferred because they can correct some of the random error. Weighted least squares must be used when the calibration points have nonhomogeneous variance. The most used methods are empirical (spline function) or semi-empirical (logit-log, logistic). The logitlog straight line is often too rigid. Logistic equation can fit numerous assays. The best empirical model is the smoothed cubic spline. Model-based methods attempt to describe the data in terms of a given theoretical model for the assay chemistry. The choice of a method to efficiently control calculations must take into account the quality of the fit, the robustness with outliers, the proper computation of confidence limits and the user-friendliness. Errors associated with the different processing steps can also be due to the calibration point distribution, the axes in which the curve is shown, the model used, and, of course the measurement errors.

Data Interpretation, Statistical↗
PubMed1990

Retinyl ester hydrolase and vitamin A status in rats treated with 3,3',4, 4'-tetrachlorobiphenyl.

Previous studies have shown that rats exposed to 3,3',4,4'-tetrachlorobiphenyl (TCB) exhibit decreased liver vitamin A stores. The activity of retinyl ester hydrolase (REH), the enzyme responsible for the hydrolysis of the storage form of vitamin A (retinyl esters) into free retinol, may therefore be altered by TCB. This study was carried out to investigate the effect of TCB on vitamin A distribution and on REH activity in the rat. REH activity was measured in liver homogenates and microsomes (650 micrograms protein), in Tris-maleate buffer 0.1 M at pH 7.2 in the presence of 150 mM CHAPS and 1.5 mM retinyl palmitate dispersed in Triton X-100 0.2%. Using these conditions, the kinetic parameters of the enzyme were determined and the inter-animal variation coefficient (10%) allowed statistical comparisons between experimental groups. Male Wistar rats of sufficient or deficient vitamin A status were treated IP with 340 mumol of TCB/kg. Vitamin A levels were significantly depressed in liver. REH activity was decreased about 20%, and serum retinol was decreased about 50%, independent of the initial vitamin A status of the animals. Vitamin A levels in lungs and testes were also decreased, suggesting that TCB could interfere with vitamin A delivery to target organs. The negative effect of TCB on REH activity in vivo was also observed when TCB was added in vitro to the incubation medium at concentrations near to those expected after in vivo treatment. TCB is a non-competitive inhibitor of retinyl palmitate hydrolase.

Animals↗
PubMed1990

Anxiolytic potential of sulpiride, clozapine and derivatives in the open-field test.

Recently acquired data question the sharp dichotomy between anxiolytics and neuroleptics, since disinhibitory effects have been measured in the rat with very low doses of haloperidol and higher doses of atypical neuroleptics in FI and DRL schedules, but also in the open-field test. That the DA transmission in certain brain regions is involved in some aspects of anxiety has recently been suggested. The present study confirms this hypothesis particularly with high doses of sulpiride (80 mg/kg) and clozapine (24 mg/kg) when tested in the open-field test. Moreover, the results show how a slight chemical modification of clozapine can give a direction to pharmacological activity with one derivative still resembling clozapine and the second one resembling haloperidol. As neuroleptics do not seem to influence the synthesis and utilization of GABA, the higher entry score observed with them would seem to depend above all on DA antagonism in the mesolimbic system.

Animals↗
PubMed1990

Effects of low doses of neuroleptics on temporal regulation in a differential reinforcement of response duration (DRRD) schedule in the dog.

It has been shown that low doses of neuroleptics could disinhibit behaviour in animals as well as in man. This study aims to measure the effects of low doses of haloperidol (0.01, 0.05, 0.1 mg/kg) and sulpiride (5, 10, 15 mg/kg) in the dog using a differential reinforcement of response duration (DRRD) schedule with positive and negative external stimuli. Together with a decrease in response rate, a leftward shift in the temporal distribution of response duration is measured. These results are discussed in terms of a deregulation of the internal clock, a lessening in the ability to wait for the reward, a reduction in the frustration of not obtaining reinforcements when errors are made and an increase in the sensibility to reinforcement through appetite stimulation or decrease in the satiety level.

Animals↗
PubMed1990

Clozapine: an atypical neuroleptic.

Since it was synthesized in 1960, much has been written about clozapine. Although a number of its properties are those of a neuroleptic, it displays marked differences from classical antipsychotics to the extent that it is currently listed as an atypical neuroleptic. A classical neuroleptic has been defined in man according to its antipsychotic properties, accompanied by extrapyramidal effects, and in animals according to its cataleptic properties, its ability to antagonize apomorphine and amphetamine stereotypies and to suppress the conditioned avoidance response. Moreover, the classical neuroleptic exerted depressive and anhedonic effects in most conditioning schedules. With clozapine, most of these properties are no longer strictly in force to the point that they call in question the validity of the tests carried out to detect the potential of neuroleptics. This article attempts to compare the characteristics of clozapine with those of classical neuroleptics from a toxicological, neuropharmacological, psychopharmacological and clinical point of view.

Animals↗
PubMed1990

International approach of the assessment of chemical risks.

One of the primary objectives of the International Programme on Chemical Safety (IPCS) which is a cooperative venture of the International Labour Organization (ILO), the United Nations Environment Programme (UNEP) and the World Health Organization (WHO), is to carry out and disseminate evaluations of the risk to human health and the environment from exposure to chemicals. These evaluations are distributed to all Member States in order to provide a scientific and objective basis that national health or other relevant authorities may be able to use for planning, and for the development of regulatory and control measures. In view of frequent discrepancies in toxicological evaluations performed by different groups, it is recommended that a mechanism be established to assure a higher degree of uniformity and harmonization in the safety assessment of chemicals, and to develop globally acceptable standardized control measures.

Accident Prevention↗
PubMed1989

Adenocarcinoma and wood.

The relation of adenocarcinoma of the facial sinuses and exposure to wood dust has been recognized for 20 years. As the tracheobronchial mucosa is similar to that lining the sinuses, a link between bronchial adenocarcinoma and wood dust exposure has been postulated. To test this hypothesis, a case-control study was conducted, based on all the histologically proven cases of adenocarcinoma of the lung reported to the tumor registry of the Doubs region of France from 1978 to 1985 and random population controls matched for age and residence. A questionnaire on occupational exposure and tobacco consumption was completed by 53 cases and 160 controls. Exposure to wood was similar for both groups, the crude relative risk (odds ratio) being 1.06; adjustment for tobacco consumption did not modify this value. Exposure to wood dust does not seem to be an occupational risk factor in the genesis of bronchial adenocarcinoma.

Adenocarcinoma↗