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Biomedical subjects

M Giroux

Publications and source records attributed to M Giroux.

At least 19 recordsLinked to original sources
PubMed1998

Serum nitrates and creatinine in workers exposed to atmospheric nitrogen oxides and ammonia.

An epidemiological survey was carried out on 332 workers in a nitrogen fertilizer factory exposed to various levels of NO, NO2, NO3- and NH3. The population was divided into six groups as a function of the atmospheres in the different workshops and compared with a control group recruited outside the factory. We investigated the relations between the exposures of the different groups and serum levels of three nitrogen-containing derivatives involved in arginine metabolism: nitrates, creatinine and urea. The workers most exposed to the hydrogenated and oxygenated compounds of nitrogen were found to have the highest serum nitrates. Further analysis of the results showed that inhaled nitrogen oxides and ammonia were only partly responsible for the circulating nitrates. The excess nitrates were thought to have an endogenous origin due to inflammatory reactions induced by the pollutants, especially ammonia. In addition, we showed that the workers from the two groups exposed to both NO and NH3 had significantly elevated levels of serum creatinine (P < 0.001). The excess creatinine was thought to have derived from the interaction of the exogenous NO with arginine metabolites.

Adult↗
PubMed1998

Prophylactic thyroidectomy for medullary thyroid carcinoma in gene carriers of MEN2 syndrome.

BACKGROUND/PURPOSE: Although medullary thyroid carcinoma (MTC) can occur sporadically, in the pediatric population it is most often associated with the multiple endocrine neoplasia syndrome (MEN type 2). Traditional screening was based on evaluation of basal and stimulated serum calcitonin levels. The recent cloning of the MEN2 gene on the RET proto-oncogene of chromosome 10 now allows for testing of gene carrier status in individuals at risk who could benefit from prophylactic treatment. The current study was undertaken to determine the appropriate age for safe total prophylactic thyroidectomy. METHODS: Over a 16-year period, 12 patients with a family history of MEN2A and one with a MEN2B underwent total thyroidectomy and central neck dissection without parathyroid autotransplantation. Four patients (31%) were treated previously for Hirschsprung's disease. RESULTS: In seven patients (mean age, 11.8 years) undergoing biochemical screening for diagnosis, multifocal MTC and C cell hyperplasia (CCH) were found in all the resected specimens. Of six patients identified with genetic screening (mean age, 9.1 years), two had elevated stimulated calcitonin levels, one (age 14) had evidence of MTC, and one (age 6) had CCH. Four patients with normal calcitonin levels had no evidence of MTC (ages 6, 8, 10) but there was one occurrence of CCH (age 11). No permanent postoperative hypoparathyroidism or recurrent laryngeal nerve damage occurred in this series. With a mean follow-up of 4 years (range, 1 to 14 years), the overall disease-free survival is 100%. CONCLUSIONS: From this study the authors conclude that total thyroidectomy can be performed safely in children and should be the treatment of choice in patients with a family history of MEN2A carrying a germinal RET mutation even if the serum basal or stimulated serum calcitonin level is normal. Total thyroidectomy should be performed as early as 5 years of age before the occurrence of CCH or MTC.

Adolescent↗
PubMed1997

Influence of maternal blood flow on the placental transfer of three opioids--fentanyl, alfentanil, sufentanil.

The placental transfer of three opioids used in peridural analgesia, fentanyl, alfentanil and sufentanil, and two reference substances, antipyrine and *H2O, was determined ex vivo in the human placental cotyledon system. (1) In the first set of experiments, the infusion rates were constant and fixed at physiological flow rates. Under these conditions, the magnitude of the materno-fetal transfer was in the following order: *H2O = antipyrine = fentanyl > alfentanil > sufentanil. No particular influence of molecular weight, lipophilia, pKa or the degree of ionization could be discerned. (2) In the second set of experiments, the influence of different flow rates, reflecting various pathophysiological conditions, was examined. There was a linear relationship between the maternal flow and the materno-fetal transfer of the three opioids. On the other hand, for antipyrine and tritiated water, the relationship was logarithmic, a difference attributed to the marked lipophilia of the opioids. (3) At high maternal flow rates, saturation was observed for all five substances due to the short duration of contact with the membrane. There were logarithmic relationships between the maternal flow and the materno-fetal transfer. (4) These findings emphasize the importance of the lipophilic and hydrophilic characteristics of drugs on placental transfer, especially in the event of fluctuations in maternal flow.

Alfentanil↗
PubMed1997

[Surgical treatment of thyroid diseases in children].

UNLABELLED: In order to review the experience of a single institution with thyroid surgery and identify prognostic factors, we did a retrospective chart review of all patients who underwent thyroid surgery between 1980 and 1995. Fifty patients, 32 girls and 18 boys, underwent thyroid surgery. Clinical presentation include a thyroid nodule (36 patients), a family history of MEN syndrome with a positive pentagastrin stimulation test (10), diffuse nodular goitre (3) and a neonatal cervical mass (1). Radiologic investigation include ultrasonography in 58% of cases, radionucleide imaging in 70% of cases. The mean age at surgery was 13.3 years and the delay between onset of symptoms and diagnostic was 13 months. Twenty-one patients had a lobectomy +/- isthmectomy, 19 had a total thyroidectomy and 10 had a subtotal thyroidectomy. Nine patients required a second surgery to complete the surgical treatment, and perform a total or near total thyroidectomy when the final pathology showed a carcinoma. A well differentiated carcinoma was found in 52% of the patients, a medullary carcinoma in 20% and a benign lesion in 28% of cases. Nine patients had local or distant metastases at initial surgery. Post-op treatment consisted of suppressive hormonotherapy in all cases of cancer and radioactive iodine when recurrence occurred in 24% of patients and when metastasis where present. Survival remained at 100%. CONCLUSION: Thyroid nodules should be rapidly investigated in children because of a high potential of cancerous lesions. With an aggressive surgical treatment and post-op I131 for recurrent lesions and metastasis the prognostic remains excellent.

Adolescent↗
PubMed1994

Expression of ADP-glucose pyrophosphorylase in maize (Zea mays L.) grain and source leaf during grain filling.

The time course of ADP-glucose pyrophosphorylase activity and of starch accumulation rate measured in grain, from pollination to maturity, in Zea mays L. plants grown outdoors, was coincident for 2 years. No such correlation was observed in the adjacent leaf, which, furthermore, presented large year-to-year differences in starch accumulation pattern. Analysis of the expression of ADP-glucose synthase at the protein levels, using antibodies directed against the Bt2 or Sh2 subunits, established that the variation of activity in the grain was explained by parallel changes in the content of both subunits. The cDNA for Bt2 and Sh2 subunits were used as probes to quantify the corresponding messenger. In grain, the time course of Bt2 and Sh2 mRNA accumulation anticipated, with a similar pattern, the specific peptide variations, which suggests a transcriptional control of expression. By contrast, the control of leaf activity by protein content was less obvious than in the grain, and changes in leaf enzyme specific activity were suggested during the first 20 d after pollination. A clone homologous to the grain Bt2 subunit cDNA was isolated from a maize leaf cDNA library, and a sequence comparison showed that the leaf clone (L2) was a partial cDNA representing one-third of the mature peptide. A 97% homology was observed between Bt2 and L2 in their coding region, but homology was poor in the 3' noncoding border. This result demonstrates that Bt2 and L2 arise from different genes presenting a tissue-specific expression pattern and provides an explanation for the earlier reported differences between leaf and grain in the size of peptide and mRNA for the Bt2-homologous subunit.

Amino Acid Sequence↗
PubMed1994

Echocardiographic detection of intracardiac thrombi complicating ventriculo-atrial shunt. Report of two cases.

Right atrial thrombi are rare but serious complications of ventriculoatrial (VA) shunts. Two hydrocephalic patients who received a VA shunt developed thromboembolic complications. The initial manifestation was malfunction of the distal end of the shunt and right heart failure. Bidimensional echocardiography demonstrated an intracardiac mass on the distal intra-auricular end of the shunt. Pulmonary scan showed multiple emboli even in the asymptomatic patient. This demonstrates the important role of bidimensional echography as a noninvasive diagnostic technique for this particular complication of a VA shunt. Medical and surgical treatment modalities are discussed.

Aged↗
PubMed1993

Abducens palsy following shunting for hydrocephalus.

Over a period of 12 years, 80 patients underwent ventricular shunting for normal pressure hydrocephalus. Three developed sixth cranial nerve palsy in the first two weeks after surgery. This uncommon complication is usually transitory following the same pattern of abducens palsy after lumbar puncture or spinal anesthesia. Traction on the nerve with local ischemia has been involved as the responsible mechanism in both instances.

Abducens Nerve↗
PubMed1993

Experimental study of transplacental passage of alpha interferon by two assay techniques.

Two methods of assaying alpha interferon (IFN-alpha) were compared during an experiment aimed at determining whether IFN-alpha crosses the human placenta. Human placentas, collected after delivery following a normal pregnancy to term, were catheterized on both sides: fetal and maternal. The IFN-alpha was introduced in known amounts in the maternal circulation and was assayed in the efferent fetal fluid. The following two detection methods were used: radioimmunoassay by competition with [125I]IFN-alpha and assay with a biological system in which IFN-alpha protected Madin-Darby bovine kidney cells from destruction by vesicular stomatitis virus. The results obtained by the two methods were in perfect agreement for the efferent fetal fluid samples. They showed the absence of placental transfer of IFN-alpha. The biological method was found to be more sensitive than radioimmunoassay for low IFN-alpha titers (< 10 IU/ml) but was less reproducible, probably owing to the use of twofold dilutions. The specificities of the two methods were similar and their practicalities were equivalent; the biological method, however, was less costly. The study illustrates the complementarity of the two methods, which were based on different principles. The agreement obtained between the two methods provides a clear confirmation of the experimental results.

Adult↗
PubMed1992

Intraventricular central neurocytoma.

A case of central neurocytoma treated surgically is described. The authors review the literature. Emphasis is placed on radiological and pathological features not previously described. In particular, the intra-operative ultrasound appearance is described. The role of adjunctive radiotherapy is also discussed.

Adolescent↗
PubMed1991

Placental transfer of glycosaminoglycans in the human perfused placental cotyledon model.

Placental transfer of unfractionated heparin (UH), of low molecular weight heparin CY 216 (LMWH) and of Dermatan sulphate (DS) was studied using the human perfused placental cotyledon model. Two different techniques were used to assess the transfer: labelled molecules and biological activities as measured by antifactor Xa or antifactor IIa activities. No biological activity was present in the fetal circulation, for any of the drugs used; however, very low fractions of the perfused radioactivity were recorded, 0.76% +/- 0.36%, 1.46% +/- 1.44% and 2.37% +/- 0.89% for DS, UH and LMWH, respectively.

Dermatan Sulfate↗
PubMed1991

Maternal and umbilical cord concentrations of fentanyl after epidural analgesia for cesarean section.

The maternal and umbilical concentrations of fentanyl were measured after epidural analgesia for cesarean section, using a highly sensitive radioimmunoassay method. Sixteen parturients were anesthetized with a single epidural injection of a mixture of 85 mg bupivacaine 0.5%, 60 mg etidocaine 1%, and 100 micrograms fentanyl with epinephrine 1:200,000. Apparent maternal individual maximum peak concentration (Cmax) of fentanyl was 0.38 +/- 0.16 ng/ml (mean +/- SD) (range 0.12-0.59 ng/ml) and the time to reach Cmax (Tmax) was 24 +/- 14 min (range 5-60 min). Infants were born 19 to 42 min after epidural administration of fentanyl (mean 27 min). Fentanyl concentrations in neonates was 0.13 +/- 0.04 ng/ml for the umbilical vein and 0.06 +/- 0.03 ng/ml for the artery. The fetus extraction ratio was 53 +/- 19% (range 20-83%). The large difference between arterial and venous concentrations of fentanyl may be due to a metabolization by the fetus and/or an uptake of the drug in the fetal tissues. Thus, even if fentanyl levels reaching the fetus after cesarean section under epidural anesthesia, using local anesthetics with 100 micrograms of fentanyl, are within safe range values, the likelihood of fentanyl uptake by fetal tissues calls for a cautious use of repeated fentanyl administration.

Analgesia, Epidural↗
PubMed1990

[Epidural hematoma of the posterior cranial fossa].

The use of CT scans has entirely modified the prognosis of epidural hematomas of the posterior cranial fossa. The analysis of a personal series of 20 cases diagnosed and treated over a 10 year period, that is 6.5% of E.D.H. cases seen in this hospital, has enabled us: to propose an anatomical study regrouping the different topographic forms observed in the literature as well as in the present series. to check the deceptive radiological appearance of these hematomas. The main sign remains the existence of a cranial fracture at the level of the occipital bone. Repeated CT scans should attempt to localize this lesion. In 15% of our cases, the lesion was only detected on the second CT scan. to recommend a simple and rapid surgical procedure in the ventral decubitus position, which does not involve the foramen magnum approach. This is performed away from the occipital junction of the venous sinus. to underline the progressive decrease in the mortality rate (10%) and the good subsequent prognosis of these apparently serious forms which have left no sequelae.

Adolescent↗
PubMed1990

Effects of pH on antipyrine transfer across the human placenta ex vivo.

The influence of pH variations on transplacental transfer of antipyrine was studied using a human placental cotyledon perfused ex vivo. The antipyrine transfer rate is positively correlated with the pH in the fetal circulation and negatively correlated with the pH in the maternal circulation. Thus, the transfer rate is negatively correlated with the difference between pH values in maternal and fetal circulations. The antipyrine transfer rate is also positively correlated with the flows in maternal and fetal circulations. The above parameters allowed to explain 50% of the variance on the transfer rates obtained in various experimental conditions. In a final series of experiments where these parameters for each placenta were fixed at identical values, a good reproducibility in the results was obtained, the variation coefficient being 17%. Thus, establishing the effect of variations in pH allowed a good standardization of the perfused cotyledon model. This effect cannot be explained by modifications in the ionized fraction of the antipyrine molecular and is probably due to physiological mechanisms.

Adult↗
PubMed1990

[Respiratory symptoms in schoolchildren in Toulouse. Influence of atmospheric pollution].

In order to get a better knowledge on respiratory illnesses of children in Toulouse, and to evaluate the influence of air pollution, 1,000 children between 8 and 11 years of age, living in five different areas of the city were observed during one year (March 1985-March 1986), together with the measure of twenty pollutants. A questionnaire was used to assess the history of respiratory diseases and the chronic respiratory pathology. According to the areas, no difference appeared, other than the frequent cough which is more important in an area with lower social income (p less than 0.01). The acute respiratory illnesses, as noted during the year of observation, had a different pattern according to the areas (p less than 0.0001). Amongst the five pollutants used for the analytic study through the cross-correlations, four: nitrogen monoxide and dioxide, black fumes, and ammonia particulate derivatives are related to the respiratory diseases.

Acute Disease↗