Biomedical subjects

J M Petit

Publications and source records attributed to J M Petit.

At least 19 recordsLinked to original sources

PubMed1997

Macrovascular disease is associated with increased plasma apolipoprotein A-IV levels in NIDDM.

Apolipoprotein A-IV (apoA-IV) might play an important role in lipoprotein metabolism, including modulation of triglyceride-rich lipoprotein catabolism, reverse cholesterol transport and cholesteryl ester transfer protein (CETP) activity. Increased apoA-IV levels have been reported in plasma from NIDDM patients. The aim of the present study was to look for a possible association between plasma apoA-IV level and prevalence of macrovascular disease in NIDDM. One hundred and thirty-six NIDDM patients were studied (71 men, 65 women). Macrovascular disease was assessed in each patient by a standardized questionnaire, physical examination, resting electrocardiogram (ECG), and laboratory evaluation (ankle/arm blood pressure ratio, continuous wave Doppler velocimetry). Moreover, patients without any history of coronary heart disease and showing a normal resting ECG underwent a bicycle exercise test or a dipyridamole thallium scintigraphy to detect possible silent myocardial ischemia. Among the 136 NIDDM patients, 56 had macrovascular disease. ApoA-IV levels were significantly higher in NIDDM patients with macrovascular disease than in NIDDM patients without macrovascular disease (20.9 +/- 8.6 vs. 13.3 +/- 5.3 mg/dl; P < 0.001). The influence of different factors, such as age, BMI, cigarette smoking, hypertension, total cholesterol, triglycerides, HDL cholesterol, apoA-IV level, apoA-IV phenotype, fasting glycemia, fasting C-peptide, and microalbuminuria, on the prevalence of macrovascular disease was analyzed using a logistic regression model. In the univariate analysis, apoA-IV level (P < 0.00001), age (P = 0.0087), hypertension (P = 0.012), microalbuminuria (P = 0.018), triglycerides (P = 0.02), and fasting C-peptide (P = 0.03) were positively associated with macrovascular disease. In the multivariate analysis, macrovascular disease was positively associated only with apoA-IV (P < 0.0001) and age (P = 0.003) and negatively associated with HDL cholesterol (P = 0.013). These results indicate that increased plasma apoA-IV level is associated with an increased prevalence of macrovascular disease in NIDDM. Moreover, apoA-IV, in NIDDM patients, appears to be a better marker for macrovascular disease than triglycerides.

Apolipoproteins A↗

PubMed1996

[Food-dependent Cushing syndrome: a new entity of organic hypercorticism].

Diagnosis of Cushing's syndrome is quite difficult in endocrinology. Spontaneous Cushing's syndrome is usually divided into two subgroups, one which is dependent on corticotropin (ACTH) and another one which is not. In the first class are Cushing's disease, the ectopic corticotropin syndrome and the rare ectopic corticotropin-releasing hormone (CRH) syndrome; these ACTH-dependent Cushing's syndrome have usually diffusely enlarged adrenal glands. In the second class are cortisol producing unilateral adrenocortical adenomas or carcinomas, and the recent Cushing's syndrome with food dependent periodic hormonogenesis. This food dependent Cushing's syndrome is an ACTH-independent Cushing's syndrome with multinodular enlargement of both adrenal glands. Pathogenesis is an aberrant adrenal sensitivity to physiologic secretion of gastric inhibitory peptide (GIP). Ectopic expression of GIP receptors on adrenal cells involve pathologic food induced cortisol secretion. Food dependent Cushing's syndrome is a new cause of Cushing's syndrome. Food induced cortisol secretion may have to be explored in the ACTH-independent Cushing's syndrome.

Adrenocortical Hyperfunction↗

PubMed1996

[Prognostic factors of survival in medullary cancers of the thyroid. Apropos of 51 cases. Clinical, biochemical and immunocytochemical study].

The aim of this study was to assess the main clinical biochemical and immunocytochemical factors influencing survival in 51 patients operated for medullary thyroid carcinoma (MTC). There were 55% of women and 37% of familial cases. Mean age was 43 +/- 3 years. The following survival variables were tested: sex, age, stage, familial disease, Serum Carcino Embryonic Antigen (CEA) and Calcitonin (CT) levels three months postoperatively, intensity of CEA and CT immunostaining, percentage of cells stained for CEA and CT. The actuarial survival rate, including postoperative mortality (N = 1), was studied by uni and multivariate analysis using a Cox model (N = 31). The 5-year survival was 69 +/- 7%. By univariate analysis, stages I or II (p < 0.0001), age of 45 years and less (p < 0.0001), normalized CEA levels (p < 0.006), percentage of CT stained cells greater than 80% (p < 0.04) and weak CT and CEA staining (p < 0.02) were significant predictors of increased survival rates. Age less than 45 and stages I or II were significant prognostic factors of goof survival on multivariate analysis (p < 0.001). We conclude that clinical criteria constitute good survival prognostic factors in patients operated for MTC. The better prognosis of familial cases was probably related to their earlier detection. The prognostic value of immunostaining remains controversial and requires further studies.

Actuarial Analysis↗

PubMed1996

[Primary hyperparathyroidism and pregnancy].

We report a case of primary Hyperparathyroidism (HPT) occuring in a 36 year old woman, during pregnancy. This woman received medical therapy to the delivery, then underwent parathyroidectomy in post-partum. Primary HPT during pregnancy is associated with increased risk of fetal loss, neonatal and maternal morbidity. Neonatal hypocalcemia is due to transient hypoparathyroidism consequent to abnormal suppression of fetal parathyroid hormone secretion by maternal hypercalcemia. Maternal hypercalcemia may be masked by hypoalbuminemia during pregnancy and often leads to aspecific symptoms which will differ the diagnosis. The recommanded treatment is parathyroidectomy which should preferably be performed during the second trimester of pregnancy; the efficacity of medical treatment is poor and transient.

Adult↗

PubMed1995

VIP-like immunoreactive projections from the dorsal raphe and caudal linear raphe nuclei to the bed nucleus of the stria terminalis demonstrated by a double immunohistochemical method in the rat.

To localize the vasoactive intestinal polypeptide (VIP)-like immunoreactive neurons at the origin of the plexuses of VIP-immunoreactive fibers found in the bed nucleus of the stria terminalis (BNST), we combined iontophoretic injections of the retrograde tracer cholera toxin B-subunit (CTb) with VIP immunocytochemistry. Following CTb injections in the BNST, 2 groups of retrogradely labeled neurons immunoreactive to VIP were detected: (1) a dorso-caudal group localized in the dorsal part of the dorsal raphe nucleus and the adjacent ventro-lateral part of the periaqueductal gray; and (2) a rostral group in the caudal linear raphe nucleus. No double-labeled cells were observed in other nuclei including those of the amygdala and the supramammillary nucleus.

Animals↗

PubMed1995

Mouse testis cell sorting according to DNA and mitochondrial changes during spermatogenesis.

Flow cytometry can measure variations in DNA content and chromatin structure as well as dramatic changes in the mitochondria of germ cells during maturation from spermatogonia to elongated spermatids. Using 10-N nonyl acridine orange (NAO), an inner mitochondrial membrane dye, it is easy to follow mitochondria rearrangements. Mouse testis cells stained with the DNA fluorescent probe propidium iodide (PI) and analyzed by flow cytometry can be discriminated on the basis of their ploidy levels into five main regions corresponding to elongated spermatids, round spermatids, diploid, S-phase, and tetraploid cells. The simultaneous use of PI and NAO demonstrated the presence of cells having low and high mitochondrial content in the haploid, diploid, and tetraploid compartments. Eleven sorting windows were selected from the bivariate analysis (PI/NAO) and the corresponding cells were identified by microscopic observation. Cells were also discriminated by two parameter analysis of DNA content vs. cell diameter. The definition of seven different regions allowed us to determine NAO or rhodamine 123 (Rh 123) uptakes in each compartment. We observed that the ratio (Rh 123/NAO) dramatically changed according to the progression of cell differentiation which occurs during spermatogenesis.

Acridine Orange↗

PubMed1995

Direct cardiolipin assay in yeast using the red fluorescence emission of 10-N-nonyl acridine orange.

The dye 10-N-nonyl-3,6-bis(dimethylamino)acridine (10-N-nonyl acridine orange) has been recently identified as a specific probe for cardiolipin (Ka = 2 x 10(6) M-1). It also interacts, at lower affinity (Ka = 7 x 10(4) M-1), with other acidic phospholipids [Petit, J. M., Maftah, A., Ratinaud, M. H. & Julien, R. (1992) Eur. J. Biochem. 209, 267-273]. In order to reduce the interference corresponding to monoacidic phospholipid binding, we have quantified cardiolipin by using a fluorimetric method based on the red fluorescence of the dye dimers formed at the diacidic phospholipid contact. Hence we have demonstrated that: (a) in yeast, the mitochondrion is the target of the dye whatever the cell metabolism; (b) membrane or protein organization and fatty acid unsaturation do not significantly modify the binding of 10-N-nonyl acridine orange. Using thin-walled vesicles, a linear relationship was established between the amount of cardiolipin and the red fluorescence emitted by the dye. Low red fluorescences were also observed with vesicles containing phosphatidylserine and phosphatidylinositol. However, at the same acidic phospholipid concentration, the fluorescence was much higher using cardiolipin-containing vesicles (fivefold that observed with phosphatidylserine-containing vesicles). Thus, 10-N-nonyl acridine orange was applied to cardiolipin quantification in yeast. This new method revealed that cells growing with a high glucose concentration contained 2.2 +/- 0.3 nmol cardiolipin/10(6) cells, whereas with lactate they contained about twice this amount (3.9 +/- 0.3 nmol cardiolipin).

Acridine Orange↗

PubMed1995

[Chronic urticaria and autoimmune thyroid diseases].

INTRODUCTION: Chronic urticaria results from multiple interactive causes. For certain authors dythyroidism is significantly more frequent in patients with chronic urticaria, often associated with other autoimmune disorders. PATIENTS AND METHODS: This study included 45 patients with chronic urticaria (29 men and 16 women, mean age 45.6 years). All underwent clinical examination for thyroid disease with assay of free T3 and T4, ultrasensitive TSH and antimicrosome and antithyroperoxidase antithyroid antibodies. RESULTS: Among the 45 patients, 8, all women, had an autoimmune thyroid disease: Graves' disease (n = 1), juvenile chronic thyroiditis (n = 1), autoimmune disease n = 6). All had goiter but most had no clinical sign suggestive of hypothyroidism or hyperthyroidism. Other clinical features or laboratory findings suggested autoimmune disorders in 3. DISCUSSION: These results suggest that a complete thyroid examination with hormone assay, especially in women, should be performed in patients with chronic urticaria. TSH and antiperoxidase antibodies appear to be the most sensitive and specific assays in patients with autoimmune thyroid disease.

Adult↗

PubMed1994

Direct analysis and significance of cardiolipin transverse distribution in mitochondrial inner membranes.

The distribution of cardiolipin across the inner mitochondrial membrane was directly determined by using the ability of the fluorescent dye 10-N-nonyl-3,6-bis(dimethylamino)acridine (10-N-nonyl acridine orange) to form dimers when it interacts with the diacidic phospholipid. Two independent methods were employed: (a) a spectrophotometric measurement of 10-N-nonyl acridine orange binding to isolated rat liver mitochondria, mitoplasts and inside-out submitochondrial particles, and (b) a flow-cytometric analysis of specific red fluorescence, emitted when two dye molecules are bound to one membrane cardiolipin; the stoichiometry of 10-N-nonyl acridine orange binding to phosphatidylserine and phosphatidylinositol, 1 mol dye/mol phospholipid, prevented dye dimerisation and subsequent red-fluorescence appearance. 57% total cardiolipin was present in the outer leaflets of inner membranes of isolated organelles, a distribution confirmed by saturation measurements for mitoplasts and inside-out submitochondrial particles. The same asymmetry was directly observed in situ with mitochondrial membranes of quiescent L1210 cells, and with mitochondrial membranes of respiring yeasts. Nevertheless, alterations in ATP synthesis and inhibition of mitochondrial protein synthesis revealed that cardiolipin distribution was apparently tightly correlated with mitochondrial membrane assembly and activity.

Acridine Orange↗

PubMed1994

Elevated serum CA19-9 levels in poorly controlled diabetic patients. Relationship with Lewis blood group.

Many non-malignant diseases may be associated with elevated serum CA19-9 levels. Recent reports suggest that diabetes mellitus may also be responsible for some elevations. In this study we investigated the influence of the glycaemic level and Lewis phenotype on the serum CA19-9 levels in diabetic patients. In 15 out of 84 patients (17.8%) serum CA19-9 exceeded 100 kU/L (highest value: 208 kU/L). CA19-9 concentrations were significantly correlated with glycosylated haemoglobin levels. On the other hand, no correlation was found between CA19-9 levels and the type of diabetes, lipase levels, or the presence of anti-islet cell antibodies. Le(a-b-) patients had significantly lower serum CA19-9 levels. This study emphasizes the frequency of CA19-9 elevations in diabetic patients without cancer.

Adult↗

PubMed1993

Assessment of fluorochromes for cellular structure and function studies by flow cytometry.

Because flow cytometry permits the analysis of individual whole cells, one of the key requirements in selecting a probe is its ability to target the site of interest into cells. In addition, dyes must possess ideal properties (ie extinction coefficient, Stoke's shift) rendering them appropriate for this methodology. Other characteristics, such as fluorescence quenching and energy transfer, inherent to the staining, provide numerous applications in flow cytometry. The available fluorophores used in flow cytometry are classified according to their cellular incorporation and binding. Thus, probes are presented and discussed as follows: 1) dyes of cellular components (DNA, RNA, proteins, lipids); 2) probes of membrane potential; 3) fluorophores that are sensitive to their microenvironment (pH, calcium, etc); and 4) those used for measurement of enzymatic activities into cells.

Animals↗

PubMed1992

10N-nonyl acridine orange interacts with cardiolipin and allows the quantification of this phospholipid in isolated mitochondria.

The acridine orange derivative, 10N-nonyl acridine orange, is an appropriate marker of the inner mitochondrial membrane in whole cells. We use membrane model systems to demonstrate that 10N-nonyl acridine orange binds to negatively charged phospholipids (cardiolipin, phosphatidylinositol and phosphatidylserine). The stoichiometry has been found to be 2 mol 10N-nonyl acridine orange/mol cardiolipin and 1 mol dye/mol phosphatidylserine or phosphatidylinositol, while, with zwitterionic phospholipids, significant binding could not be detected. The affinity constants were 2 x 10(6) M-1 for cardiolipin-10N-nonyl-acridine-orange association and only 7 x 10(4) M-1 for that of phosphatidylserine and phosphatidylinositol association. The high affinity of the dye for cardiolipin may be explained by two essential interactions; firstly an electrostatic interaction between the quaternary ammonium of nonyl acridine orange and the ionized phosphate residues of cardiolipin and secondly, hydrophobic interactions between adjacent chromophores. A linear relationship was demonstrated between the cardiolipin content of model membranes and the incorporated dye. Consequently, a convenient and rapid method for cardiolipin quantification in membranes was established and applied to the cardiolipin-containing organelle, the mitochondrion.

Acridine Orange↗

PubMed1992

Cinchonine, a potent efflux inhibitor to circumvent anthracycline resistance in vivo.

Circumvention of multidrug resistance is a new field of investigation in cancer chemotherapy, and safe and potent multidrug resistance inhibitors are needed for clinical use. We investigated several analogues of quinine for their ability to increase anthracycline uptake in resistant cancer cells. Cinchonine was the most potent inhibitor of anthracycline resistance in vitro, and its activity was little altered by serum proteins. Serum from rats treated with i.v. cinchonine produced greater uptake of doxorubicin in cancer cells (DHD/K12/PROb rat colon cells and K562/ADM human leukemic cells) than did serum from quinine-treated rats (ex vivo assay). Cinchonine was more effective than quinine in reducing tumor mass and increasing the survival of rats inoculated i.p. with DHD/K12/PROb cells and treated i.p. with deoxydoxorubicin. Moreover, the acute toxicity of cinchonine in rats and mice was lower than that of other quinine-related compounds. The lower toxicity and greater potentiation of in vivo anthracycline activity produced by cinchonine are favorable characteristics for its use as an anti-multidrug resistance agent in future clinical trials.

Animals↗

PubMed1992

Confluence-dependent resistance in human colon cancer cells: role of reduced drug accumulation and low intrinsic chemosensitivity of resting cells.

In vitro sensitivity of HT29 human colon cancer cells to doxorubicin (DXR), vincristine (VCR), etoposide (VP16), cisplatin (CDDP), melphalan (L-PAM) and 5-fluorouracil (5FU) was markedly reduced when cell-culture density increased. For some drugs, confluence-dependent resistance (CDR) was partly due to decreased intracellular drug accumulation; the ratio of mean intracellular drug content of non confluent to confluent cells (NC/C) was 2.5 for DXR, 4.1 for VCR and 7.4 for VP16. Altered drug penetration with confluence could be related to decrease of plasma membrane fluidity as measured by the fluorescence polarization method. Reduction of drug intracellular accumulation was nil or weak for L-PAM (NC/C = 1.0), CDDP (NC/C = 1.2) and 5 FU (NC/C = 1.8). Even if drug concentration was adjusted in culture medium to produce similar intracellular drug content in confluent and non confluent cells, higher intrinsic resistance of confluent cells was still evidenced for DXR and VP16 but not for VCR, the only agent without direct interaction with DNA. DXR- and VP16-induced DNA breakage was also less important in confluent than in non-confluent cells. CDR appeared closely related to an increased proportion of non-cycling cells at confluence, as demonstrated by flow cytometry, expression of nuclear antigen recognized by Ki67 MAb and expression of topoisomerase II. CDR is probably a major factor in the poor sensitivity of colorectal adenocarcinomas to chemotherapy.

Antineoplastic Agents↗

PubMed1992

Effects of chronic atropine administration on regional vasoactive intestinal polypeptide concentrations in rat brain.

We studied the effects of 14 days' treatment with atropine sulfate (10 or 20 mg/kg per day) or atropine methyl bromide (20 mg/kg per day) on the concentration of vasoactive intestinal polypeptide like-immunoreactivity (VIP-LI) in the rat brain. VIP-LI in the anterior pituitary as well as brain areas dissected from treated and control rats was measured by radioimmunoassay. VIP-LI in the hypothalamus, and especially in the suprachiasmatic nucleus, was not affected by chronic atropine sulfate administration. Conversely, the same treatment induced a decrease in VIP-LI in the cerebral cortex, dorsal raphe, locus coeruleus, ventrolateral and dorsolateral medulla. In these structures, the decrease in VIP-LI was probably due to muscarinic receptor blockade in the central nervous system rather than in the peripheral nervous system since variations in VIP-LI were not observed after atropine methyl bromide treatment. These findings suggest the existence of a muscarinic control of VIP-LI in discrete brain areas of the rat and particularly in caudal brainstem structures.

Animals↗

PubMed1992

NADH-dependent dehydrogenase activity estimation by flow cytometric analysis of 3-(4,5-dimethylthiazolyl-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction.

MTT reduction is usually analysed by colorimetric assay to study mitochondrial dehydrogenase activity as a test of cytotoxicity. This enzymatic reaction produces dark-blue granules of formazan, which increase cell refringency. In this work, we define the conditions for MTT use in quantitative flow cytometric analysis. MTT reduction provides a non-fluorescent dye usable by this technique to study an intracellular NADH-dependent dehydrogenase activity in vital cells. We observe that formazan production increases asymptotically with cell concentration and that this temperature-dependent Michaelis enzymatic reduction is produced essentially by mitochondrial dehydrogenases. In isolated mitochondria from rat hepatocytes and in whole L1210 murine leukemia cells, the Michaelis constants (KM) observed in the presence of respiratory substrates were, respectively, 10 microM and 500 microM. The inhibition of mitochondrial protein synthesis by chloramphenicol, which induces a rise of MTT reduction due to the correlative stimulation of glycolysis (Pasteur effect), is a limit of the MTT assay as a cytotoxicity test.

Animals↗

PubMed1992

[Experimental chemotherapy of peritoneal carcinomatosis of colonic origin in rats].

Animal models are useful in the evaluation of adjuvant or palliative treatment modalities of human colonic adenocarcinoma. In the present paper, the efficacy of 22 usual chemotherapeutic agents was evaluated in a model of peritoneal carcinomatosis of colonic origin in the BD IX rat. Mitomycin, cisplatine, carboplatine, cyclophosphamide, ifosfamide, and thiotepa were very effective agents on microscopic carcinomatosis (treatment given 3 days after an intraperitoneal inoculation of 1 x 10(6) DHD/K12/PROb cells). Intravenous administration was as effective as the intraperitoneal route, except for anthracyclines and 5-fluorouracil. Rats treated at early stages by thiotepa or cisplatin survived up to 4 months after cell injection and did not display tumor at autopsy. Administered late (15 days after cell injection), none of the drugs were able to cure the rats with carcinomatosis.

Animals↗

PubMed1991

Evaluation of 2-methoxyacetic acid toxicity on mouse germ cells by flow cytometry.

Flow cytometric (FCM) DNA content measurements were carried out on testicular monocellular suspensions obtained from mice exposed per os to a single dose of 50, 100, 300, 600, and 900 mg/kg body weight (b.w.) of 2-methoxyacetic acid (MAA) in order to investigate its cytotoxic action on germ cells. The effects of MAA were evaluated 2, 7, 14, 28, and 45 d after treatment in terms of altered cell type ratios in FCM fluorescence distribution histograms. Testis weight and histological tissue sections were also analyzed. MAA induced marked changes in the relative percentages of tetraploid and haploid cells, indicating the occurrence of cytotoxic damage on primary spermatocytes. Multiparameter FCM analysis showed that, besides its action on nucleic acid synthesis, MAA can also affect the cellular energy metabolism reflected in an altered mitochondrial mass distribution on round spermatids surviving the MAA treatment. This study demonstrates that rapid and unique FCM procedures can be usefully applied in reproductive toxicology.

Acetates↗