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D Petit

Publications and source records attributed to D Petit.

At least 19 recordsLinked to original sources
PubMed1992

Spectral analysis of the rapid eye movement sleep electroencephalogram in right and left temporal regions: a biological marker of Alzheimer's disease.

Spectral analysis of electroencephalograms (EEGs) for both wakefulness and rapid eye movement (REM) sleep was performed over the temporal regions in 8 patients with mild to moderate Alzheimer's disease and in 8 age-matched control subjects. EEG slowing in Alzheimer patients was found to be much more prominent during REM sleep than during wakefulness. In addition, asymmetry on the awake EEG of Alzheimer patients was found to be even more prominent than on the REM sleep EEG. When EEG values of the most impaired hemisphere during REM sleep were examined, no overlap was found between the two groups either for the ratio of slow to fast frequencies or for percent power of each of the frequency bands. This was not the case for the awake EEG. These results suggest that diagnostically meaningful cutoff values for discriminating patients with mild to moderate Alzheimer's disease from age-matched control subjects can be derived from the REM sleep EEG of the temporal lobe.

Aged↗
PubMed1992

[Use of Cell Saver 4 in traumatology. Apropos of 9 cases].

During a recent seven mouth period of time, patients with intrathoracic and intraabdominal injury had recovery of shed blood utilizing a Haemonetics Cell Saver. Blood is suctioned from the surgical field or with tube thoracostomy. Autotransfusion is sufficient for four patients; five others patients need blood transfusion, for intraoperative or postoperative hemorrhage. However, the decrease of transfusion requirement is evident, and autotransfusion is equivalent to 8.6 concentrated red cells units for each patient, as 2.6 homologous bank blood concentrated red cell units. The difficulties are nurse training, and cost (to be compared with homologous bank blood cost); but autotransfusion with Haemonetics Cell Saver 4 is sizeable part of transfusion therapy of acute trauma.

Adult↗
PubMed1991

Generation of monoclonal antibodies specific for ras p21 Glu-12 oncoproteins: detection in carcinogen-induced mammary carcinomas.

ras genes have been shown to become oncogenes by single point mutations which result in amino acid substitutions that affect either their GTPase activity (positions 12, 13, 59, 61) or their affinity for GTP and GDP. Ras oncogenes and their corresponding proteins have been described in a variety of human cancers as well as in animal tumors induced by physical and chemical carcinogens. One of these animal tumor systems involves the induction of mammary carcinomas in rats by a single dose of N-nitroso-N-methylurea (NMU), a methylating carcinogen. These NMU-induced mammary carcinomas contain transforming H-ras genes activated by G----A transitions in the second nucleotide of their 12th codon, presumably a consequence of the pre-mutagenic lesions induced by NMU. These G----A mutations result in the replacement of the normal glycine in the 12th position of the ras p21 protein by a glutamic acid residue. In this study, we report the generation of monoclonal antibodies (Mab) reactive with oncogenic ras p21 proteins containing glutamic acid at position 12 (p21 Glu-12). Mab designated E184 specifically recognized activated ras p21 Glu-12 proteins but not normal p21 (Gly-12) or p21 proteins activated by other position 12 substitutions including arginine, aspartic acid, cysteine, valine or serine residues. Western blot analysis of NMU-induced mammary carcinomas demonstrated that Mab E184 recognized p21 proteins expressed in these rat tumors but not p21 present in normal tissues nor in other carcinogen-induced tumors known to carry H-ras oncogenes activated by mutations at position 61.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Bilateral receptive fields in cortical area SII: contribution of the corpus callosum and other interhemispheric commissures.

The corpus callosum contributes to the interhemispheric transfer of somatosensory information. Since the somatosensory pathways are essentially crossed, a number of studies have postulated that the corpus callosum may be responsible for the presence of bilateral receptive fields (RFs) in cortical area SII. Moreover, subcortical structures, as well as some of the other commissures, may also contribute to the bilateral nature of these cells. In order to assess the relative importance of the corpus callosum, this study compared the RF properties of cells in area SII of callosum-sectioned cats to normal cats, using single-cell recordings. Results showed that the corpus callosum makes an important contribution to the bilateral activation of cells in SII, since the proportion of cells with bilateral RFs found in callosum-sectioned cats was less than half that obtained in normal cats. The decrease in the proportion of bilateral RFs was found for all body regions with the exception of the face. However, the substantial number of bilateral RFs remaining in callosotomized cats indicates that this structure is not the sole contributor to the bilateral activation of cells in SII. In order to determine whether this residual bilateral activation might be mediated by the other interhemispheric commissures, a group of cats was subjected, besides the callosotomy, to the additional transection of their subcortical commissures, including the anterior, posterior, habenular, and intertectal commissures, as well as the massa intermedia. When this group of deep-split cats was compared to the callosotomized group, the results indicated that the contribution of the other commissures to bilateral activation is negligible, since approximately the same proportion of bilateral RFs was encountered in the two groups. The relative importance of the callosal contribution to bilateral RFs of different body regions is discussed with respect to the roles commonly attributed to this structure.

Animals↗
PubMed1989

Lipid and lipoprotein synthesis in isolated and cultured hepatocytes from lean and obese Zucker rats.

Hepatocytes were isolated by EDTA perfusion of livers from lean (Fa/-) and obese (fa/fa) Zucker rats. Triacylglycerol (TG) and sn-glycerol 3-phosphate were increased in fa/fa hepatocytes, but free fatty acids, cholesterol and phospholipid concentrations were similar in both groups. In spite of an identical fatty acid uptake rate, glycerolipid synthesis was higher in obese compared to lean rat hepatocytes, and this difference remained for at least 2-3 days of culture. Triacylglycerol mass secretion was 2-fold higher in obese than in lean rat hepatocytes. This was confirmed by the higher incorporation of labeled glycerol and oleic acid into the medium TG fraction floating at density 1.006 g/ml. Density gradient ultracentrifugation of [14C]oleate-labeled lipoproteins showed that fa/fa hepatocytes secreted more TG-rich lipoproteins, and that 87% of the label was in the VLDL fraction compared with 67% in the medium of Fa/- hepatocytes. Decreased utilisation of leucine for protein synthesis in obese rat compared to lean rat hepatocytes was associated with enhanced leucine oxidation to CO2. [35S]Methionine incorporation showed an identical cell protein synthesis rate. Autoradiography after PAGE separation of secreted apolipoproteins (apoBh, Bl, apoA-VI, apoE, apoA-I, apoC) showed an identical pattern in both cell types.

Animals↗
PubMed1989

Effect of vasodilators on hepatic microcirculation in cirrhosis: a study in the isolated perfused rat liver.

We studied the effects of a series of vasodilators on intrahepatic vascular resistance of isolated perfused cirrhotic rat livers in basal conditions and during norepinephrine-induced vasoconstriction. Cirrhosis was induced by repeated intraperitoneal injections of carbon tetrachloride. The vasodilators were a nonselective beta-adrenergic antagonist (propranolol), an alpha 1-adrenergic antagonist (prazosin), a nonselective beta-adrenergic agonist (isoproterenol), an alpha 2-agonist (clonidine), nitrovasodilators (nitroglycerin and nitroprusside), calcium channel blockers (verapamil, diltiazem, nifedipine), papaverine, diazoxide and pentoxifylline. In basal conditions, isoproterenol, nitroglycerin, papaverine, pentoxifylline and nitroprusside demonstrated significant vasodilatory activity. However, the response was weak and isoproterenol was the only drug active in the therapeutic range of concentrations. Propranolol, prazosin, verapamil, diltiazem, nifedipine and diazoxide were ineffective. Prazosin, papaverine and pentoxifylline reduced norepinephrine-induced vasoconstriction, whereas isoproterenol, clonidine and propranolol were ineffective. We conclude that several vasodilators can reduce resistance in the cirrhotic rat liver, but their potency is low and few are effective at therapeutic concentrations. Furthermore, their activity may be blunted when resistance is increased by norepinephrine.

Animals↗
PubMed1988

Effects of ciprofibrate and fenofibrate on liver lipids and lipoprotein synthesis in normo- and hyperlipidemic rats.

The plasma lipoprotein and liver lipid composition, and the lipid, cholesterol and apolipoprotein synthesis have been studied in normal and diet-induced hyperlipidemic rats, receiving ciprofibrate (2.5 mg/kg body weight) or fenofibrate (50 mg/kg b.w.) for 8 days. Ciprofibrate is about 25-fold more active than fenofibrate in reducing plasma triglyceride and cholesterol concentrations both in normolipemic and in hyperlipemic rats. In normolipemic rats ciprofibrate reduced the concentration and the lipid content of all lipoprotein classes. The incorporation of [14C]palmitate and [3H]leucine into the lipoproteins was reduced by ciprofibrate and fenofibrate. The reduction in lipoprotein production was confirmed by prevention of Triton-induced hyperlipemia. Liver and plasma cholesterol synthesis estimated by 3H2O and [14C]mevalonate incorporation indicated an inhibitory effect on HMG-CoA reductase. Administration of ciprofibrate or fenofibrate to rats fed a fat and cholesterol-rich diet partially prevented liver steatosis and hyperlipemia. Both drugs reduced the overproduction of lower density lipoproteins. The ratio of (VLDL + LDL)-cholesterol/HDL-cholesterol which was increased by the diet alone from 0.4 (normal) to 11 remained close to the normal value in the animals receiving ciprofibrate. In the hyperlipemic animals, ciprofibrate reduced the incorporation of [3H]oleate into the liver and plasma glycerolipid and increased cholesterol esterification. Ciprofibrate efficiently reduces plasma levels of cholesterol, triglyceride and phospholipid. Cholesterol and glycerolipid synthesis in the liver were significantly reduced leading to a lower lipoprotein secretion rate in both normolipidemic and diet-induced hyperlipidemic rats.

Animals↗
PubMed1988

Lipoprotein secretion in lean and obese Zucker female rats in vivo and in a single-pass-perfused liver preparation.

The plasma lipoprotein composition as well as lipoprotein synthesis and secretion were studied in vivo and in a single-pass-perfused liver preparation in lean and obese Zucker rats. Compared with their lean littermates the levels in the plasma of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) + low density lipoprotein (LDL) and high density lipoprotein (HDL) were increased 4-, 2- and 2.5 fold, respectively, in obese rats. In these rats both VLDL and IDL + LDL were enriched in triglycerides, while the HDL were enriched in cholesterol. Although the VLDL and IDL + LDL protein concentrations were the same in lean and obese rats, the HDL protein concentration was 3-fold greater in the obese rats. Both the lean and obese rats incorporated similar amounts of [14C]leucine into total liver protein. However, obese rats incorporated 2.5-fold and 6-fold more [14C]leucine into VLDL and HDL in vivo, 2.7-fold and 1.7 fold more [35S]methionine in VLDL and HDL present in the perfusate, than did lean rats. The perfusate [35S]S-labelled apoproteins (apo-B100, B48; apo-E, apo-AI, apo-AIV and apo-C) were separated by gel electrophoresis and identified by autoradiography. Incorporation of [3H]glycerol into liver, VLDL, IDL + LDL and HDL triglycerides was 2-, 48-, 13- and 1.5-fold higher in obese than in lean rats, respectively. The [3H]-labelled triglycerides in VLDL and IDL + LDL present in the perfusate was 5.4-fold and 4.4-fold more in obese rat. There was no difference in the incorporation of [3H]glycerol into triglycerides of perfusate HDL between the two genotypes of rats. Thus, the hypertriglyceridaemia observed in obese Zucker rats results from very high synthetic rates of both the lipid and protein moieties of plasma lipoproteins. Before this study, no report of the simultaneous triglycerides and protein synthesis in vivo and in a single-pass-perfused liver preparations had been reported.

Animals↗
PubMed1987

Rats with lesions in anteromedial extrastriate cortex fail to learn a visuosomatic conditional response.

The involvement of rat anteromedial extrastriate cortex (area AM, in the anterior portion of area 18b) in the integration of visual and somatic cues was assessed behaviorally. Following restricted bilateral lesions of selected cortical regions, rats were tested on their ability to retain or relearn a conditional visuosomatic discrimination task learned prior to surgery. Two compound, visuosomatic stimuli were used: white or black associated with either one of two degrees of roughness. The use of a guided-response procedure was essential for rats to learn this difficult conditional bimodal task. None of the 6 rats with lesions aimed at area AM retained the habit postoperatively. Four of these rats were incapable of relearning the task after 3 postoperative training series, and they had either extensive lesions of area AM or relatively small, symmetric damage of anterior portions of AM. The remaining two rats with lesions in area AM were able to relearn the task in the second postoperative training series, and their lesions either were restricted to posteromedial aspects of area AM or they involved asymmetric loci in anterior area AM. In contrast to rats with lesions of area AM, rats with lesions in visual cortex in areas 17 and 18a, or in auditory cortex in area 41, were able either to retain the task or to relearn in the first postoperative training series. These results indicate that the integrity of area AM appears necessary for rats to discriminate between pairs of compound stimuli that differ in brightness and roughness. The behavioural data point to the notion that this area might be involved in the integration of these types of visual and somatic stimuli. In addition, our finding that performance was largely unimpaired following extensive lesions of lateral extrastriate area supports previous reports indicating that medial and lateral extrastriate visual areas differ in function.

Animals↗
PubMed1986

A monoclonal antibody reactive with an activated ras protein expressing valine at position 12.

Activated ras transforming genes have been described in a variety of neoplasms and encode 21,000-Dalton (p21) proteins with amino acid substitutions at positions 12, 13, and 61. In this report we describe a monoclonal antibody designated DWP that reacts specifically with synthetic dodecapeptides containing valine at position 12, to a lesser extent with peptides containing cysteine at position 12 and not with peptides containing glycine, arginine, serine, aspartic acid, glutamic acid or alanine at the same position. Western blot and immunoperoxidase studies showed that DWP specifically reacts with activated rasH or rasK proteins in NIH cells transformed by DNA from the human carcinoma cells that encode valine at position 12. DWP did not react with normal p21s encoding glycine at position 12, nor with activated p21s encoding aspartic acid, glutamic acid, arginine, serine, or cysteine at position 12. A survey of human tumor cell lines demonstrated that DWP reacted with the human bladder carcinoma cell line T24 but not with human tumor cell lines previously shown to contain other activating mutations at positions 12 or 61. DWP and perhaps additional antibodies that specifically react with alterations at positions 12 or 61 of the ras protein may be valuable in determining the presence and frequency of activated ras proteins in human malignancy.

Amino Acid Sequence↗
PubMed1986

Fecal bile acid excretion and liver cholesterol synthesis after sucralfate and cholestyramine administration in the rat.

The relative ability of the resin cholestyramine and sucralfate (disucrose octasulfate) to bind bile acids in the gastro intestinal tract and increase fecal bile acid excretion has been studied in normal rats under standard diet. Plasma and liver cholesterol concentrations and in vitro cholesterol synthesis from 14C-acetate by liver slices, have been determined before and after one and three weeks of drug administration (0.5 or 1.0 g/100 g food). Plasma and liver cholesterol levels were unchanged after one week of treatment, but a moderate decrease in liver cholesterol content was observed after 3 weeks administration of cholestyramine and, to a lesser extent of sucralfate. Both drugs increase fecal bile acid excretion with a definitely higher effect of cholestyramine at either dose or period of administration. However, the resin produced a higher bile acid excretion after one week than after three weeks, whereas sucralfate effect increases with the time of administration. In vitro cholesterogenesis was clearly increased by cholestyramine and moderately by sucralfate although 14C-acetate incorporation into cholesterol was not quantitatively correlated to the amount of bile acid excreted in feces. The potential interest of sucralfate as bile acid sequestrant and hypocholesterolemic agent in man deserves further investigations.

Aluminum↗
PubMed1986

Monoclonal antibody specific for an activated RAS protein.

Activated RAS transforming genes that encode proteins (p21s) with amino acid substitutions at positions 12, 13, or 61 have been detected in 10-20% of human neoplasms. This report describes a monoclonal antibody (DWP) raised against a synthetic peptide corresponding to amino acids 5-16 of a mutated RAS gene encoding Val instead of Gly at position 12. DWP reacted in competition assays with peptides containing Val or Cys at position 12, but did not react with peptides containing Gly, Arg, Ser, Ala, Asp, or Glu at position 12. Immunoblot analysis of transformed NIH cells and human carcinoma cell lines showed that DWP reacts specifically with activated RAS proteins containing Val at position 12 and not with normal p21s or p21s activated by other amino acid substitutions at positions 12 and 61. Immunohistochemical studies showed that DWP-labeled transformed NIH cells and human carcinoma cells contained p21s with either Val or Cys at position 12 but not normal or other activated p21s. In contrast to the specificity seen with human carcinoma cell lines, analysis of formalin-fixed, primary carcinoma specimens indicated that positive immunoperoxidase staining with DWP did not necessarily correlate with immunoblot and transfection assays for the presence of activated RAS proteins. Immunohistochemical studies did show, however, that DWP preferentially binds human carcinoma cells.

Amino Acid Sequence↗
PubMed1985

[Chromosomal phylogeny of 7 species of Sciurinae].

The sequence of chromosomal rearrangements that leads to the karyotypes of living species of Sciurinae is hardly compatible with a dichotomic evolution. The most probable hypothesis is that of a populational chromosomal evolution: the different lineages would have been isolated successively from an ancestral population in which several chromosomal rearrangements would have spread to more or less important fractions of the population. The proposed order in the succession of these isolations (Marmota monax, Sciurus vulgaris, Callosciurus flavimanus, Heliosciurus gambianus, Atlantoxerus getulus, Eutamias sibiricus then Menetes berdmorei) fits the paleontological data.

Animals↗
PubMed1984

Lead in petrol.

Explore the source record for details and available documents.

Environmental Pollution↗
PubMed1984

[Great degree of homology between the ancestral karyotype of squirrels (rodents) and that of primates and carnivores].

The karyotype of 7 species of Sciurinae representative of 6 tribes were compared: Atlantoxerus getulus, Menetes berdmorei, Callosciurus flavimanus, Heliosciurus gambianus, Sciurus vulgaris, Eutamias sibiricus, and Marmota monax. Homoeologies between almost all chromosome segments were found. Numerous similarities with the karyotypes of certain Primates and Carnivora were observed. A presumed ancestral karyotype of the Sciurinae is proposed.

Animals↗
PubMed1976

Effects of glycerol on VLDL secretion by the isolated rat liver.

Stimulation of VLDL production by increasing fatty acid availability is now well established. However, a possible regulatory role of glycerol, another lipid precursor, in VLDL synthesis by the liver has not yet been substaniated. The present experiments investigate this problem using the isolated perfused rat liver. [14C] Glycerol uptake and metabolism were studied at two different glycerol concentrations: 1 mumol/perfusate (control) or 1.6 mmol/perfusate. VLDL production and lipid synthesis were investigated using [14C]leucine and several labelled fatty acids as precursors in control and glycerol-overloaded livers. Neoglycogenesis and lipogenesis from glycerol carbons are negligible in our conditions. The absolute amount of glycerol, but not the precentage, taken up by the liver, increased after raising its concentration in the perfusate. A major part of exogenous (plasmatic) glycerol was esterified with endogenous (non plasmatic) fatty acids. Incorporation of radioactive fatty acids into liver or plasma lipids was lower than in the the control group. Significant differences were observed between saturated and unsaturated fatty acids used as lipid precursors. Production of VLDL as assessed by radioactive leucine and fatty acid incorporation in the VLDL of the perfusate was depressed by glycerol. Glycerol partly inhibits the normal stimulation of VLDL production by plasmatic fatty acid overload.

Animals↗