Biomedical subjects
Publications and source records attributed to F Brion.
Central nervous system abnormalities are recognized complications of anorexia nervosa. However, peripheral nerve disorders are less well documented in this condition. We report 2 cases of peroneal nerve palsy in anorectic patients who had a tendency to spend long periods of time sitting cross-legged. The respective roles of mechanical compression and malnutrition in the pathogenesis of peroneal nerve palsy in anorexia nervosa are discussed.
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This article resumes the work we have accomplished in the past few years. Cholecystokinin sulfation is an important post-translational modification necessary for the biological activity of this peptide hormone. The tyrosyl protein sulfotransferase (TPST) activity from rat cerebral cortex was characterized. TPST activity is most probably responsible for the endogenous sulfation of CCK. TPST reaction kinetic properties were studied using radiolabeled 3'-phosphoadenosine 5'-phosphosulfate (PAPS) and the non-sulfated peptide acceptor terbutyloxycarbonyl-cholecystokinin octapeptide (BocCCK-8(ns)) as substrates, and brain microsomes as the enzyme source. The BocCCK-8 sulfating reaction data is consistent with the idea that TPST forward reaction follows an ordered Bi Bi mechanism. PAPS biosynthesis and availability was studied in slices from rat cerebral cortex incubated in the presence of [35S]sulfate. There is a rapid and dynamic turnover of the steady-state level of PAPS in brain cells which is decreased by depolarizing agents such as potassium, veratridine and glutamate. Furthermore, the presence of a membrane-bound PAPS biosynthesis inhibitor was observed. These results are discussed in view of the biological importance that the cell sulfating pathways might play in nerve cell activity.
Intestinal permeability was evaluated in 17 healthy young children (control group), aged 4.3 +/- 1.9 years (mean +/- SD), weight 15.4 +/- 5.5 kg and in 11 infants with food allergy (allergic group, aged 2.3 +/- 1.6 years, weight 9.5 +/- 1.5 kg). In the two groups, the urinary excretion of two non-metabolized sugars (mannitol, lactulose) was measured by gas-chromatography after oral administration. Measurement of urinary content of these sugars 5 hours after administration in the control group showed a clearance of 20.2 +/- 8.6% for mannitol and 0.44 +/- 0.18% for lactulose. The lactulose/mannitol ratio in the same group was equal to 0.023 +/- 0.008. When compared to the control group, the 11 patients of the allergic group presented a normal mannitol urinary excretion (16.5 +/- 13.4%, p = NS, Student's t-test) and an increase in the lactulose excretion (1.36 +/- 0.92%, p < 0.001). Moreover, the allergic group showed a lactulose/mannitol ratio that was significantly different (0.105 +/- 0.071, p < 0.001). The intestinal permeability test for the diagnosis of food allergies seems to be a sensitive and non-invasive test that is well suited to the paediatric practice.
1. Tyrosyl protein sulfotransferase (TPS) activity in the newborn and mature rat brain was studied using the cholecystokinin derivative terbutyloxycarbonyl-Asp-Tyr-Met-Gly-Trp-Met-Asp-PheNH2, BocCCK-8(ns), as the peptide substrate. 2. TPS activity was enriched 4 times in the microsomal and synaptic vesicular enriched fractions of rat cerebral cortex. 3. CCK-8 content, in the subcellular fractions and the peptide sulfation activity distribution was in accord with the hypothesis that tyrosyl protein sulfotransferase plays a key role in the maturation process of bioactive CCK. 4. TPS activity measured in membranes from newborn brain was 2.5 times higher than the activity observed in the mature brain membranes with a Vmax = 0.83 +/- 0.05 and 0.31 +/- 0.02 respectively. The apparent KM for the sulfate donor, 3'-phosphoadenosine 5'-phosphosulfate (PAPS), was similar, 94 +/- 4 nM and 90 +/- 6 nM and the KM for the peptide substrate, BocCCK-8(ns), was 234 +/- 16 microM and 160 +/- 12 microM in the newborn and adult brain membranes respectively. 5. TPS activity reached normal mature values within 20 days of age. 6. These data support the idea that tyrosyl protein sulfation is an important process in the secretion mechanism and in the CCK maturation.
A new method was tested for estimating time after death in the middle range of postmortem interval (weeks). Creatinine muscular concentration in human cadaver is positively correlated to postmortem estimation. Temperature should be mainly related to the creatinine transformation rate. A stronger correlation was found at 11 degrees C up to 30 days and at 20 degrees Celsius up to 15 days.
A novel in vivo binding test was developed in order to evaluate the degree of occupancy of enkephalinase (EC 3.4.24.11), a membrane-bound metallopeptidase, in cerebral and peripheral tissues of mice treated with enkephalinase inhibitors. The probe selected for this purpose was the prodrug [3H]acetorphan, a lipophilic diesterified derivative of the potent enkephalinase inhibitor thiorphan readily releasing the latter by tissue hydrolysis. In order to validate the in vivo binding assay, [3H]thiorphan binding to membranes was first studied in vitro. [3H]Thiorphan binding to cerebral and peripheral tissues (lung and kidney) was saturable over a low nonspecific binding, occurring with a KD of 0.6 nM consistent with the Ki of the compound as enkephalinase inhibitor. [3H]Thiorphan binding varied largely among various tissues and was highly correlated with the catalytic activity of enkephalinase, thus indicating a selective labeling of the peptidase. After the i.v. administration of [3H]acetorphan a large fraction of the radioactivity remained bound to membranes isolated by a rapid filtration assay. Bound radioactivity mainly corresponded to [3H] thiorphan as identified by high-performance liquid chromatography analysis of kidney membranes, whereas unchanged [3H]acetorphan was not detectable. In vivo binding generated by [3H]acetorphan was saturable, with maximum binding sites values which were in rather good agreement with corresponding maximum binding sites values of [3H]thiorphan binding in vitro, particularly in brain. Specific in vivo binding was calculated as the difference between total and a generally low, nonspecific binding evaluated in mice receiving a large dose of nonlabeled acetorphan. Specific in vivo binding varied largely among tissues and generally reflected the abundance of enkephalinase molecules in the latter.(ABSTRACT TRUNCATED AT 250 WORDS)
The formation of the sulfate donor [35S]3'-phosphoadenosine 5'-phosphosulfate (PAPS) from inorganic [35S]sulfate was studied using a novel assay. The assay was based on the quantitative transfer of radioactivity from [35S]PAPS to beta-naphthol under the action of phenolsulfotransferase activity from rat brain cytosol, with the [35S]beta-naphthyl sulfate formed being isolated by polystyrene bead chromatography. This simple assay was validated by comparison of results with those derived from direct assay of [35S]PAPS isolated by either TLC or ion exchange chromatography. [35S]PAPS formation by a high-speed supernatant of rat cerebral cortex occurred with an optimal pH of approximately 7.6, varied linearly with time and protein concentration, and depended on the presence of Mg2+-ATP. The latter could not be replaced by other nucleotides such as GTP, UTP, or CTP, which at 1-5 mM concentrations inhibited the reaction. Mg2+ could not be replaced by Mn2+, which at micromolar concentrations inhibited the reaction. The apparent Km values of Mg2+-ATP (at 0.1 mM [35S]sulfate) and inorganic sulfate (at 5 mM Mg2+-ATP) were 2.7 and 0.2 mM, respectively. These kinetics parameters corresponded to those reported for purified ATP sulfurylase (EC 2.7.7.4), the enzyme responsible for the first step of PAPS synthesis in liver. The product of its reaction, [35S]adenosine 5'-phosphosulfate (APS), could not be detected after incubations, an observation implying that the action of APS kinase was not rate limiting in cerebral extracts tested under the selected experimental conditions. [35S]PAPS formation was detectable in cytosolic fractions from various brain regions, which displayed only limited differences in synthesizing activity.(ABSTRACT TRUNCATED AT 250 WORDS)
Slices from rat cerebral cortex incubated in the presence of 2-deoxy[3H]glucose accumulate the sugar mainly in the form of its phosphorylated derivative. 2-Deoxy[3H]glucose uptake, measured under conditions of initial velocity, is stimulated by 50-100% in the presence of depolarising agents (KCl, veratridine) or the excitatory amino acids L- and D-glutamate, L-aspartate and L-cysteate in millimolar concentrations. In contrast a variety of putative neurotransmitters are ineffective on this test. The stimulations elicited by KCl or excitatory amino acids consist in significant increases in both the apparent Km and Vmax values of the 2-deoxyglucose transport system. The effect of excitatory amino acids is not significantly modified in the presence of tetrodotoxin or when the extracellular Ca2+ concentration is diminished, whereas it is significantly reduced in the presence of ouabain. Hence stimulation of 2-deoxy[3H]glucose uptake and phosphorylation may indirectly reflect the activation of Na+, K+-adenosine 5'-triphosphatases triggered by excitatory amino acids in target cells. The stimulation of 2-deoxy[3H]glucose uptake elicited by the three excitatory amino acids is antagonised in an apparently competitive manner by glutamate diethyl ester (apparent Ki value of congruent to 15 mM) whereas the KCl-induced stimulation is not modified. In contrast a variety of other amino acid agonists (including quisqualate, kainate, N-methyl D-aspartate) or antagonists (including gamma-D-glutamyl glycine acid and 2-amino-5-phosphonovalerate) are inactive, indicating that the metabolic response is not mediated by any of the receptor subclasses identified electrophysiologically.
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The effects of intravenously infused 5(S)hydroxy-6(R)-S-cysteinyl-7,9,-trans,11,14,-cis eicosatetraenoic acid (leukotriene E) (LTE), one of the leukotriene constituents of slow-reacting substance of anaphylaxis (SRS-A), on pulmonary resistance (RL) and dynamic compliance (Cdyn), breathing frequency, and mean systemic arterial pressure were determined in both anesthetized and unanesthetized guinea pigs. The LTE caused a dose-dependent increase of RL and decrease in Cdyn over the range of doses from 100 to 10,000 ng/kg with significance effects at the highest doses. The onset of effect after a significant dose occurred within 30 s and was maximal 1 to 3 min after infusion. The LTE elicits a significantly greater effect on RL for a given change in Cdyn than occurs with LTC or LTD indicating that LTE is a less selective peripheral airway agonist than LTC or LTD. The LTD infusion resembled LTC or LTD in evoking a systemic arterial hypotension that was preceded by a brief initial period of hypertension in unanesthetized animals.
Sixteen structural analogs of leukotrienes C and D were tested for their contractile activities on guinea pig pulmonary parenchymal strip and ileum. The analogs differed from the native structures in the position of either the thioether-linked peptide side chain or the hydroxyl group (or both) or in the number and positions of ethylenic bonds. Analogs in which the thioether-linked peptide chain was attached other than at the C-6 position had substantial reductions in activity on both smooth muscle preparations, whereas analogs in which the various ethylenic bonds were saturated retained substantial contractile activity in both assays. These observations demonstrate that, although a hydrophobic region of the eicosinoid is necessary for contractile activity, the length of this segment is more critical than its precise stereochemistry. Analogs of leukotrienes based on the possibility of parallel biosynthetic routes deriving from 8-, 11-, and 15-hydroperoxyeicosatetraenoic acid as precursors were found to effect a comparatively weak contractile response so that their role as biological agents in this respect seems unlikely.
Twenty-three structural analogs of the leukotriene components of slow reacting substance of anaphylaxis (SRS-A), in which the polar regions of the leukotriene were systematically modified, were tested for their contractile activities on guinea pig pulmonary parenchymal strips and guinea pig ileum. The structural modifications allowed evaluation of the separate contributions of the four polar units in the C-1 to C-6 region of the SRS-A leukotrienes to smooth muscle spasmogenic activity. The free NH2-terminal amino group of the S-linked peptide was necessary for full activity, and its deletion or substitution reduced activity by more than one but less than two orders of magnitude. A similar level of importance was apparent for the free glycine carboxyl group. In contrast, a free eicosanoid carboxyl at C-1 is not required for full activity on the airway and for substantial activity on the ileum. A role for the C-5 hydroxyl is indicated by the inactivity of the one available 5-desoxy analog. Nucleophilic, divalent sulfur is not critical to leukotriene D (LTD) activity, in that one sulfoxide had substantial function. The conformational relationship between the eicosanoid and peptide moieties of LTD is of considerable importance in that epimers at the C-5 or C-6 position were less active than LTD by more than two orders of magnitude. Several lines of evidence suggest that the relative geometrical arrangement of the C20 chain and the peptide unit is important to activity, consistent with the existence of a true receptor for LTD.
The mechanism of vitamin D participation in the processes of monoamine regulation was studied. Central and peripheral endogenous norepinephrine levels were compared in vitamin D deficient rats, in preventative vitamin D3 (1 IU/day) administered rats, and in lactose (20% of the diet) administered rats, lactose being known to increase intestinal absorption of calcium. Vitamin D deficiency resulted in a significant decrease in endogenous norepinephrine. The decrease was of variable magnitude according to the considered organs. The adrenal dopamine level was also less in vitamin D deficient rats than in rats given vitamin D in preventive treatment. However, it remained in the brain. In the absence of vitamin D dietary lactose restored blood calcium and endogenous norepinephrine levels in all the tissues, except in the liver. It appears that the decrease in norepinephrine storage in vitamin D deficient rats resulted from a lack of calcium rather than from the absence of vitamin D.
A technique for sampling organisms on the hands, the so-called "disc method" was tested in three surgical departments, in parallel with the classical method of direct finger print on a gel medium. The respective value of 6 products for washing the hands was assessed in order to demonstrate the possibilities offered by the technique proposed, which is truly quantitative. In particular, it was shown, "in the field", that three products had a very valuable action (Chlorhexidine, Hexachlorophene and a quarternary ammonium salt), but simple washing with Marseille soap followed by rincing with alcohol gave good results, limited only by the absence of any persistent bactericidal action.
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